Manual for erosion and sediment control in Georgia [2001]

STATE SOIL &

COMMISSION ON

MANUAL FOR EROSION AND SEDIMENT CONTROL
IN GEORGIA
Fifth Edition 2000
includes any changes through January 1, 2001
WATER CONSERVATI
SOILOUR BASIC HERITAGE
1937 GEORGIA
GEORGIA SOIL AND WATER CONSERVATION COMMISSION
P.O. Box 8024 4310 Lexington Road
Athens, GA 30603 706-542-3065
706-542-4242 fax
www.gaswcc.org

The preparation of this manual was financed in part through a grant from the U.S. Environmental Protection Agency to the Environmental Protection Division of the Georgia Department of Natural Resources under Provisions of Section 319(h) of the Federal Water Pollution Control Act, as amended.
All programs and services of the federal, state and local agencies listed above are available on a nondiscriminatory basis without regard to race, color, national origin, religion, sex, age, marital status, handicap or disability. If you need this document in an alternative format, call (706) 542-3065.
GaSWCC (Amended - 2000)

PREFACE TO THE FIFTH EDITION
The fourth edition of the "Manual for Erosion and Sediment Control in Georgia" has been revised with a focus on erosion control. Implementation of newly researched products has been incorporated to expand on the traditional erosion and sediment control practices included in the fourth edition. These new products have been proven to aid in controlling erosion and subsequent sedimentation in a cost-effective manner.
It is important that this publication is used as a guideline and that "creativity" must be utilized when necessary to fully protect a site from erosion and subsequent sedimentation. The fifth edition has been modified to include detailed guidance on what is required on erosion and sediment control plans.
Several important additions and changes have been incorporated into the fifth edition. The definition of "stabilized" and "final stabilization" as well as time-lines for the application for vegetation have been included. Eight new practices have been added. These are Construction Road Stabilization, Stream Diversion Channel, Filter Ring, Disturbed Area Stabilization (With Sodding), Erosion Control Matting and Blankets, Polyacrylamide (PAM), Streambank Stabilization, and Tackifiers and Binders.
Every effort has been made to incorporate pertinent aspects of the Georgia Department of Transportation's erosion and sediment control specifications. Additional information on "linear" projects has been included as well.
It is hoped that users of this manual will realize the significant changes and recognize that technology changes rapidly in the erosion and sediment control arena. The Commission is dedicated to providing the State of Georgia with the latest "proven" erosion and sediment control practices.
The Commission is appreciative of all of the help and guidance received during the revision of the manual. Many thanks go to the Georgia Department of Transportation, Natural Resources Conservation Service, DNR Environmental Protection Division, DNR Wildlife and Fisheries, University of Georgia, UGA Institute of Ecology, Gwinnett County Planning and Development, the Upper Chattahoochee Riverkeeper, and Jim Spotts Ph.D., CPESC.

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FOREWORD
Perhaps the most harmful damage to Georgia's land and water resources is incurred through unchecked and uncorrected erosion and sediment deposition. Years of work have done much to remedy the situation. There has also been created an awareness that efforts must continue to further reduce the volume of the sediment pollution in all the state's waters.
While ongoing work in soil and water conservation has been of considerable success, it was recognized that some state regulation of land-disturbing activities could add a needed dimension to the overall control effort. The General Assembly responded to this need, and in 1975, the Erosion and Sedimentation Act (O.C.G.A. 12-7-1 et seq.) was passed. The Act has been amended several times since then.
The Act requires counties and municipalities to have erosion and sediment control ordinances or be covered under state regulations. While the Soil and Water Conservation Districts provide assistance in this at the local level, the State Soil and Water Conservation Commission provides expert, step-by-step guidance for activities under such ordinances through a comprehensive publication of reference information. Thus the "Manual for Erosion and Sediment Control in Georgia" can serve as a technical guide in formulating plans for land-disturbing activities. In preparing the manual, the State Conservation Commission is indebted to the many hundreds of researchers, engineers, farmers, conservationists and others who, over the years, made possible the accumulation of information on modern conservation.
The criteria, standards and specifications contained in Chapter 6 must be incorporated into all local erosion and sediment control programs. The remaining chapters and sections of this Manual contain guidelines and support materials to assist users in the implementation of best management practices in accordance with the provisions of the Erosion and Sedimentation Act.

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PREFACE FOREWORD CHAPTER 1 CHAPTER 2 CHAPTER 3 CHAPTER 4 CHAPTER 5 CHAPTER 6 APPENDIX A-1 APPENDIX A-2 APPENDIX A-3 APPENDIX B-1 APPENDIX B-2 APPENDIX C APPENDIX D APPENDIX E APPENDIX F REFERENCES

TABLE OF CONTENTS
Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii ................................................................. v The Erosion and Sedimentation Act of 1975 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 Sediment and Erosion Control Processes, Principles and Practices . . . . . . . . . 2-1 Planning and Plans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 Local Programs: Principles and Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 Sources of Assistance and Resource Information . . . . . . . . . . . . . . . . . . . . . . . 5-1 BMP Standards and Specifications for General Land-Disturbing Activities . . . . 6-1 Estimating Runoff from Urban Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1-1 Peak Discharges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2-1 Procedural Guide for Computing Runoff By Rational Method . . . . . . . . . . . . A-3-1 Soil Series Interpretations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1-1 Soil Loss Predictions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2-1 Riprap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1 Model Soil Erosion and Sedimentation Control Ordinance . . . . . . . . . . . . . . . . . D-1 Conversion Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-1 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-1

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CHAPTER 1

THE EROSION AND
SEDIMENTATION ACT
OF 1975
On April 24, 1975, the Honorable George Busbee, Governor of the State of Georgia, signed into law Act 599, the Erosion and Sedimentation Act of 1975 (O.C.G.A. 12-7-1 et. seq.) This landmark legislation is the result of over five years of exhausting work, debate and legislative compromise.
With the passage of the Act, Georgia joined the few far-sighted states adopting legislation specifically designed to protect soil and water resources. But, of all the various state laws, Georgia's shows the greatest concern for local implementation and local enforcement. There now exists in Georgia a mechanism whereby local decision makers can do something about the abuses of soil and water resources which have troubled them so long.
The Erosion and Sedimentation Act of 1975 states: "It is found that soil erosion and sediment deposition onto lands and into waters within the watersheds of this State are occurring as a result of widespread failure to apply proper soil erosion and sedimentation control practices in land clearing, soil movement and construction activities, and that such erosion and sediment deposition result in pollution of State waters and damage to domestic, agricultural, recreational, fish and wildlife, and other resource uses. It is, therefore, declared to be the policy of this State and the intent of this Act to strengthen and extend the present erosion and sediment control program to conserve and protect land, water, air and other resources of this State."
Numerous studies have been made which indicate the vast amounts of sediment eroding from our lands. It has been estimated, for example, that approximately 4 billion tons of sediment are eroded in the United States each year (13).
Sediment in Georgia comes from many sources including farmland, roadside construction sites and even city streets. Studies show sediment yields from agricultural areas can average about seven tons per acre per year (17). Lands undergoing development for roadways and urban and suburban development are experiencing losses at a much higher rate. A research project at Cartersville, Georgia, indicated that total area erosion from roadbanks without proper vegetative cover can exceed over 350 tons per acre per year (9).
GaSWCC (Amended - 1995)

Figure 1-1. - Erosion on this construction site was the result of poor planning.
Figure 1-2. - Advanced gully erosion on an abandoned construction site.
Historically, farm land has been the greatest source of sediment. The trend was reversed around the midpoint of the century with much idle land or land in row crops planted to perennial grasses or trees. Records from various waterworks in Georgia tell the effects of this movement. Water analysis at the Atlanta waterworks, for instance, showed that the average turbidity of water taken from the Chattahoochee River dropped from 400 parts per million in the 1930's to less than 40 ppm in the 1950's. It is now reported to be about 25 ppm (17). Similar data was recorded in Newnan, Columbus, Macon and other cities.
Erosion damage is costly to repair, often requiring regrading or replacement of eroded soil and replacement of damaged pavements and structures. Sediment damages are not only unnecessary but extremely costly. A report shows that on five harbor projects in Michigan, a total of over one million cubic yards of man-induced sediment was removed at a cost of $2.50-$4.00 per cubic yard. Yet the establishment of control measures to hold this soil in place would have cost only 10-15 cents per cubic yard (29)!
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Figure 1-3. - Sediment from upstream erosion has severely reduced the capacity of this culvert.
Georgia's soil and water conservation districts have been charged with performing a vital role in the implementation of Act 599. Since their formation beginning in 1937, the districts have worked toward treating each acre of land in accordance with its capabilities. This has been done on two-thirds of Georgia's 37 million acres with most of the work on agricultural lands. The Erosion And Sedimentation Act, however, will deal primarily with land-disturbing activities in urban and urbanizing areas. It should be remembered that the same methodology and expertise is required in planning for the conservation of soil and water on any lands.
It is believed that Act 599 will effectively reduce the major source of water pollution in Georgia. And because two-thirds of the population is located in urban areas covering less than seven percent of the land, this reduction in erosion damage to natural resources will occur in locations most critical to the general health and well-being of the people.
Figure 1-4. - Removing sediment from this tennis court was a costly and time consuming operation.
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Figure 1-5. - If unchecked, sediment would gradually fill this lake.
PROVISIONS UNDER ACT 599
Act 599 requires that governing authorities of Georgia's 159 counties and 537 incorporated municipalities adopt comprehensive ordinances governing land-disturbing activities within their boundaries. The ordinances must contain technical principles as provided in the law and procedures for issuance of permits.
There are minimum standards included in the law. Local ordinances may, however, be more stringent than the minimum requirements of the law. Municipalities may specify in their ordinances that the responsibilities of permit issuance, inspection, and enforcement be delegated to the local Planning and Zoning Commission.
Municipalities and counties failing to have in effect a comprehensive erosion and sediment control program will be subject to rules and regulations developed by the Environmental Protection Division of the Georgia Department of Natural Resources.This division of state government would then issue permits, perform inspections and become the enforcer for all land-disturbing activities within their boundaries until such time as the local authorities adopt an ordinance.
LAND-DISTURBING ACTIVITY:
"Any activity which may result in soil erosion from water or wind and the movement of sediments into state water or onto lands within the state, including, but not limited to:
1. clearing 2. dredging 3. grading 4. excavating 5. transporting 6. filling"
GaSWCC (Amended - 1995)

The law could have a significant impact on any area's natural resource base because it requires detailed planning before land-disturbing activities are undertaken.The law requires that erosion and sediment control plans for each non-exempt activity be prepared and submitted with application to the local unit of government for a permit. The plans will then be forwarded to the appropriate Soil and Water Conservation District. This agreement, in effect, would bypass District approval if the local unit demonstrates that it possesses the capability and expertise to conduct erosion and sediment control plan review.
After a thorough analysis of the plans, they will be returned to the issuing authority with the District's recommendations upon which the issuing authority will issue or deny permits. Should a permit be denied because of a discrepancy in the plans, such discrepancies must be made apparent to the applicant. The law requires that a permit be issued or denied within a period not to exceed 45 days after the plan and applications are submitted. If a permit is denied there are appeal procedures provided for in the Act.
The law deals basically with processes. That is, permit processing, plan processing, etc. However, technical guidelines are included as minimum requirements which may be strengthened by local units of government. The technical requirements, if skillfully utilized in planning for land-disturbing activities, will result in orderly development but with the ultimate result of conserving and protecting soil resources.
There are several exclusions or exemptions written into the Act. Home gardens and individual home landscaping require no permit nor does the construction of single-family residences for individual owners. Surface mining and granite quarrying are covered by other laws and are exempt, as are all agricultural and forestry practices. Projects carried out under the technical supervision of the USDA Natural Resources Conservation Service are exempt.
Public utilities regulated by the Public Service Commission are exempt but required to meet State minimum erosion and sedimentation control standards. Also exempted are land-disturbing projects financed in any way by the Department of Transportation or the Georgia Highway and Tollway Authority, as well as any road construction or maintenance project undertaken by any county or municipality, provided they meet State minimum requirements.
Key exemptions to the permit provisions of the Act are found in the requirements that any land change to 1.1 acres or less will require a permit if they are within 200 feet of state waters.

At this point it should be repeated that Act 599 provides minimum requirements to be adopted by local units of government. Said units are permitted to strengthen ordinances by elimination of certain exclusions.
LAND DISTURBING ACTIVITY DOES NOT INCLUDE:
1. Surface mining 2. Granite quarrying 3. Minor land-disturbing activities 4. a. Construction of single-family residences
under contract to the owner b. Construction of single-family residences not
part of a larger project; provided the activity meets State minimum requirements. 5. Agricultural and forestry practices 6. Any project under the technical supervision of the Natural Resources Conservation Service 7. Projects involving 1.1 acres or less (if not within 200 feet of state waters) 8. Construction or maintenance by the Department of Transportation, Georgia Highway Authority, Georgia Tollway Authority; road construction or maintenance project undertaken by counties or municipalities; provided the activity meets State minimum requirements. 9. Projects undertaken by EMCs or municipal electrical systems, or any public utility under the Public Service Commission, provided the activity meets State minimum requirements.

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THE EROSION AND
SEDIMENTATION ACT
STATE SOIL & WATER
CONSERVATION COMMISSION
SOIL AND WATER CONSERVATION
DISTRICT

Figure 1-6.
AGENCIES AND AUTHORITIES EROSION AND SEDIMENTATION ACT OF 1975
COUNTY OR MUNICIPALITY

PLAN* REVIEW

FOR COUNTIES NOT DESIGNATED
AS ISSUING AUTHORITIES

SOIL AND WATER CONSERVATION
DISTRICT

ADVICE CONSENT

RULES AND REGULATIONS DEVELOPED BY
EPD

ADOPTED BY BOARD OF NATURAL
RESOURCES

LOCAL PLANNING COMMISSION

PLAN* REVIEW

SOIL AND WATER CONSERVATION
DISTRICT

PERMIT AND ENFORCEMENT

PERMIT AND ENFORCEMENT

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SOIL AND WATER CONSERVATION
DISTRICT

PLAN REVIEW

ENVIRONMENTAL PROTECTION DIVISION

PERMIT AND ENFORCEMENT

DEVELOPER

* This step may be bypassed if the local unit of government: (1) Has been certified by the Department of Natural Resources as meeting or exceeding the standards, requirements, and provisions of the Act and
(2) Enters into a Memorandum of Agreement with the local District.

THE MANUAL
This manual has been assembled to provide guidance in the implementation of Act 599. It was written for four specific audiences.
1. The land disturbers: landowners, developers and their consultants, architects, engineers, land surveyors, planners, etc.
2. The enforcers: officials and employees of local units of government charged with responsibility of administering and enforcing the law on a local level and the Environmental Protection Division when it is the issuing authority.
3. The plan reviewers: the Soil and Water Conservation Districts and local issuing authorities.
4. The plan preparers.

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GaSWCC (Amended - 1995)

CHAPTER 2
SEDIMENT AND EROSION CONTROL PROCESSES, PRINCIPLES AND PRACTICES
Erosion is the process by which the land surface is worn away by the action of wind, water, ice or gravity. Water-generated erosion is unquestionably the most damaging and is thus the problem to which this manual is primarily addressed.
Natural, or geologic, erosion has been occurring at a relatively slow rate since the earth was formed and is a tremendous factor in creating the earth as we know it today. The picturesque mountains of the north, the fertile farmlands of the Piedmont and the productive estuaries of the coastal zone are all products of geologic erosion and sedimentation in Georgia. Excepting some cases of shore and stream channel erosion, natural erosion occurs at a very slow and uniform rate and remains a vital factor in maintaining environmental balance.
Figure 2-1. - Erosion of this coastal shore is an example of geologic erosion.
Human alteration of the earth's surface can lead to "accelerated erosion." This is a classic example of environmental abuse and is normally the result of poor planning and unorganized construction.
Erosion by water is a process of breaking loose and transporting soil particles. The energy of raindrops falling on denuded or exposed soils is the key element.
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The annual impact energy of raindrops, for instance, has been estimated to average approximately 30 billion foot-pounds or the equivalent of 10 thousand tons of T.N.T. per square mile (19). Water flowing over exposed soil picks up detached soil particles. As the velocity of flowing water increased, additional soil particles are detached and transported.Water flows have a tendency to concentrate. This first creates small channels or rills and eventually gullies of varying widths and depths. As the volume and velocity of runoff increases in unprotected streams and channels, additional erosion occurs on stream banks and bottoms.
Figure 2.2. - Energy of falling raindrops has detached and transported soil particles from
unprotected areas. Sedimentation is the process where soil particles settle out of suspension as the velocity of water decreases. The heavier particles, gravel and sand, settle out more rapidly than fine silt and clay particles. The characteristic reddish color of Georgia's streams in the Piedmont results from suspended microscopic clay particles. Unfortunately, these particles are easily transported and settle out very slowly. It is difficult and perhaps impossible to totally eliminate the transportation of these fine particles even with the most effective erosion control programs.
FACTORS INFLUENCING EROSION
The erosion process is influenced primarily by climate, topography, soils, and vegetative cover.
Climate. The frequency, intensity and duration of rainfall and temperature extremes are principle factors influencing the volume of runoff from a given area. As the volume and intensity of rainfall increases, the ability of water to detach and transport soil particle increases. When storms are frequent, intense, and of long duration, the potential for erosion of bare soils is high. Temperature has a major influence on soil erosion. Frozen soils are relatively erosion resistant. However, soils with high moisture content are subject to "spew," or uplift by freezing action, and are usually very easily eroded upon thawing.
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Topography. The size, shape and slope characteristics of a watershed influence the amount and duration of runoff. The greater the slope length and gradient, the greater the potential for both runoff and erosion. Velocities of water will increase as the distance from the top of the slope or the grade of the slope increases.
Soils. The soil type will determine its vulnerability to erosion. Properties determining the erodibility of a soil are texture, structure, organic matter content and permeability. Soil containing high percentages of fine sands and silt are normally the most erodible. As the clay and organic matter content of these soils increases, the erodibility decreases. Clays act as a binder to soil particles thus reducing erodibility. But, while clays have a tendency to resist erosion, they are easily transported by water once eroded. Soils high in organic matter resist rain drop impact and the organic matter also increases the binding characteristics of the soil. Clearly, well-

graded and well-drained gravels are usually the least erodible soils. The high infiltration rates and permeabilities either prevent or delay runoff.
Vegetative Cover. Vegetative cover is an extremely important factor in reducing erosion from a site. It will:
a. Absorb energy of rain drops.
b. Bind soil particles.
c. Slow velocity of runoff water.
d. Increase the ability of a soil to absorb water.
e. Remove subsurface water between rainfalls through the process of evapotranspiration.
By limiting the amount of vegetation disturbed and the exposure of soils to erosive elements, soil erosion can be greatly reduced.

INCHES & TONS / ACRES

60 50 40 30 20 10 0
1940

1945

1950

YEARS

1955

* Soil Loss Varies Annually

RAINFALL
SOIL LOSS 1959

TONS PER ACRE

NUMBER

2.5

6

THUNDERSTORMS

2.0

5

4 1.5

3 1.0
2

0.5

SOIL LOSS

1

0 JAN. FEB. MAR. APR. MAY JUN. JUL. AUG. SEP. OCT. NOV. DEC.
* Soil Loss Varies Seasonally
*Information taken from: Barnett, A.P. and B.H. Hendrickson, "Erosion on Piedmont Soils," Soil Conservation Magazine, USDA, Soil Conservation Service, Volume XXVI, No. 2 Sept. 1960
Figure 2-3.

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GaSWCC (Amended - 2000)

GENERAL DESIGN PRINCIPLES
For an erosion and sedimentation control program to be effective, it is imperative that provisions for sediment control measures be made in the planning stage. These planned measures, when conscientiously and expeditiously applied during construction, will result in orderly development without adverse environmental degradation.
From the previous discussion on erosion and sediment control processes and factors affecting erosion, basic technical principles can be formulated to assist the project planner or designer in providing for effective sediment control. It is felt that these certain key principles must be utilized to the maximum extent possible on all projects.
Fit the Activity to the Topography and Soils. Detailed planning should be employed to assure that roadways, buildings and other permanent features of the activity conform to the natural characteristics of the site. Large graded areas should be located on the most level portion of the site. Areas subject to flooding should be avoided. Areas of steep slopes, erodible soils with severe limitations for the intended uses should not be utilized without overcoming the limitations through sound engineering practices. Erosion control, development and maintenance costs can be minimized if a site is selected

Figure 2-5. - Unstable Soil Conditions, as on this roadbank, should be avoided.
for a specific activity rather than attempting to modify the site to conform to the proposed activity.
The Disturbed Area and the Duration of Exposure to Erosion Elements Should be Minimized. Clearing of natural vegetation should be limited to only those areas of the site to be developed at a given time. Natural vegetation should be retained, protected and supplemented with construction scheduling employed to limit the duration of soil exposure. Major land clearing and grading operations should be scheduled during seasons of low potential runoff.

Figure 2-6.

Figure 2-4. - Permanent facilities for this development were planned to fit the topography and soil type.
GaSWCC (Amended - 2000)

Figure 2-7. - Vegetation on this road bank will reduce erosion to a minimum.
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Stabilize Disturbed Areas Immediately. Permanent structures, temporary or permanent vegetation, and mulch, or a combination of these measures, should be employed as quickly as possible after the land is disturbed. Temporary vegetation and mulches can be most effective on areas where it is not practical to establish permanent vegetation. These temporary measures should be employed immediately after rough grading is completed if a delay is anticipated in obtaining finished grade. The finished slope of a cut or fill should be stable and ease of maintenance considered in the design. Stabilize all roadways, parking areas, and paved areas with a gravel subbase, temporary vegetation or mulch.

Figure 2-10. - This vegetated waterway will safely convey storm water away from this swimming pool.

Figure 2-8. - Hydroseeding equipment can efficiently and quickly establish disturbed areas.

Figure 2-11. - Storm water detention structures will reduce storm water runoff from developed areas.
Retain Sediment. Sediment basins, sediment barriers and related structures should be installed to filter or trap sediment on the site to be disturbed. The most effective method of controlling sediment, however is to control erosion at its source. Sediment retention structures should be planned to retain sediment when erosion control methods are not practical, are insufficient, in the process of being installed, or have failed due to some unforeseen factor.

Figure 2-9. - Jute matting can assist in rapid establishment of vegetation.
Retain or Accommodate Runoff. Runoff from the development should be safely conveyed to a stable outlet using storm drains, diversions, stable waterways or similar measures. Consideration should also be given to the installation of storm water detention structures to prevent flooding and damage to downstream facilities resulting from increased runoff from the site. Temporary or permanent facilities for conveyance of storm water should be designed to withstand the velocities of projected peak discharges. These facilities should be operational as soon as possible after the start of construction.
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Figure 2-12. - This temporary sediment basin effectively trapped sediment from upstream
erosion.
GaSWCC (Amended - 2000)

Figure 2-13. - A temporary sediment basin converted to a permanent pond enhances landscape.
Figure 2-14. - An undersized culvert in this roadway has created an obstruction to floodwaters.
Figure 2-15. - The result when residences are constructed in flood prone areas.
GaSWCC (Amended - 1995)

Do Not Encroach Upon Watercourses. Permanent buildings should not be subjected to flooding, sediment damages or erosion hazards. Earth fills should not be constructed in flood-prone areas so as to adversely obstruct water flows or increase downstream velocity of water flows. When necessary to span a flood-prone area or watercourse, bridge and culvert openings should be sized to permit passage of peak discharges without causing undue restrictions in water flows or without creating excessive downstream velocities. Uses of floodprone areas should be limited to activities which would not suffer excessive damages from flooding, scour and sediment. Temporary bridges or culverts should be employed when construction equipment is required to cross natural or constructed channels.
EROSION AND SEDIMENTATION CONTROL PRACTICES
Severe erosion on lands undergoing land-disturbing activities can be reduced if proper control measures are implemented. The timely application of erosion and sediment control measures will minimize the time that the soils are exposed, control runoff, shield the soil from erosive forces, and bind the soils.
A most effective tool in controlling erosion is good site planning which includes planning and installation of erosion and sediment control practices. In Chapter 6 of this manual are standards and specifications for such practices which can be utilized on areas undergoing land-disturbing activities. These standards were developed to establish statewide uniformity in selection, design, review, approval, installation and maintenance of conservation practices.They establish minimum requirements for planning, designing and installing the practices on disturbed areas.
For effective erosion control, a combination of these measures must be employed. Alternates may be approved for individual erosion and sediment control plans. In general, they fall into the rather broad categories of structural practices and vegetative measures.
VEGETATIVE CONSERVATION MEASURES
Vegetative practices may be applied singularly or in combination with other conservation measures. They may be either short lived or of a permanent nature. Subsoils, mixtures of soils and soils with varying organic matter content will be encountered when soil surfaces are disturbed. Unfavorable growth conditions such as acidity, low fertility, compaction and adverse moisture contents are often prevalent. These conditions are difficult to overcome but must be eliminated if adequate plant growth is to be obtained. Steep gradients and long slopes are often present on areas to be vegetated. These ar-
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eas are subject to erosive forces from rainfall impact and flowing water and will require special techniques and grasses which will resist erosion. Establishing vegetation is possible with techniques and plants developed over the years.
Temporary Vegetation. In many instances, grading of areas is completed at a time when it is not practical to try to establish permanent vegetation. These areas can be stabilized by planting instead a variety of temporary annual grasses such as rye grass, rye, small grains and similar species. These temporary grasses will provide a rapid cover that can later be worked into the soil to provide organic matter when permanent vegetation is established. Every effort should be made to select temporary plants that will be compatible with the final permanent vegetation.
Permanent Vegetation. A wide selection of various grasses, legumes, ground cover, trees and shrubs can be used for permanent vegetation. If a high level of management is possible, an even wider range of plants can be used.
It is imperative that the final selection of plants be based on the adaptability of those plants to the topography and climate. Ease of establishment, life expectancy, maintenance requirements, aesthetics and any other special qualities should be considered. It is desirable to select plants requiring little maintenance. Many plants can be used to improve the aesthetics of a site and still be effective soil stabilizers. Special attention should be given to steep cut and fill slopes where plants requiring little maintenance must be utilized.
Mulching. Due to time constraints, it may be impractical to stabilize an area with vegetation. Excellent temporary soil stabilization can be otherwise achieved using wood chips, straw, hay, asphalt emulsion, jute matting and synthetic fibers. Areas where final grade has been reached can be stabilized with mulch and over seeded at the proper time for permanent grasses. Mulches allow for greater infiltration of water into soil; reduce the amount of runoff; retain seeds, fertilizer and lime in place; and improve soil moisture and temperature conditions. Mulch is essential in establishing good stands of grasses and legumes on disturbed areas. In order to prevent movement by wind or water, it is important that it be anchored to the soil.
Following are examples of vegetative practices suitable for utilization on disturbed land. A map code has been assigned to each practice and appears at the beginning of the title of each practice.

Bf - BUFFER ZONE
A strip of undisturbed original vegetation, enhanced or restored existing vegetation, or the re-establishment of vegetation surrounding an area of disturbance or bordering streams, ponds, wetlands, lakes, and coastal waters.
Cs - COASTAL DUNE STABILIZATION (WITH VEGETATION)
Planting vegetation on dunes that are denuded, artificially constructed, or re-nourished.
Ds1 - DISTURBED AREA STABILIZATION (WITH MULCHING ONLY)
Using plant residues or other suitable materials on the soil surface to reduce runoff and erosion, conserve moisture, prevent soil compaction and crusting, control undesirable vegetation, modify soil temperature and to increase biological activity in the soil. This practice is applicable where stabilizing disturbed or denuded areas is not practical utilizing seeding or plantings.
Ds2 - DISTURBED AREA STABILIZATION (WITH TEMPORARY SEEDING)
A temporary vegetative cover with fast growing seedings for disturbed or denuded areas. This practice is applicable for up to six months or until permanent vegetative cover can be installed. It should be coordinated with permanent measures to assure economical and effective stabilization. Techniques for establishing temporary cover utilizing both conventional and hydraulic seeding equipment are included.
Ds3 - DISTURBED AREA STABILIZATION (WITH PERMANENT VEGETATION)
A permanent vegetative cover such as trees, shrubs, vines, grasses and legume on disturbed or denuded areas. It will apply on cut and fill slopes, earth spillways, borrow areas, spoil areas and severely eroded or gullied lands. Techniques utilizing both conventional and hydraulic seeding equipment are discussed.
Ds4 - DISTURBED AREA STABILIZATION (WITH SODDING)
A permanent vegetative cover using sods on highly erodible or critically eroded lands. Sods provide immediate ground cover and help filter sediments and nutrients.

2-6

GaSWCC (Amended - 2000)

Du - DUST CONTROL ON DISTURBED AREAS

Controlling the surface and air movements of dust on construction sites, roadways and similar sites. Methods and materials which can be used include mulches, vegetative cover, spray-on adhesives, mechanical manipulation of existing soils surfaces, irrigation, barriers, chemicals, and stone surface covers.

Mb - EROSION CONTROL MATTING AND BLANKETS

A protective covering (blanket) or soil stabilization mat used to establish permanent vegetation on steep slopes, channels, or shorelines. Blankets and mats provide an excellent microclimate, which protects young vegetation and promotes establishment.

Pm - POLYACRYLAMIDE (PAM)

The land application of product containing anionic polyacrylamide (PAM) as temporary soil binding agents to reduce soil erosion. PAM reduces erosion from wind and water on construction sites.

Sb - STREAMBANK STABILIZATION (USING PERMANENT VEGETATION)

The use of readily available native plant materials to maintain and enhance streambanks, or to prevent, or restore and repair small streambank erosion problems.

Tb - TACKIFIERS AND BINDERS

Substances used to anchor straw or hay mulch by causing the organic material to bind together. Tackifiers and binders reduce runoff and erosion as well as conserve moisture and prevent surface compaction.

EFFECTIVENESS OF GROUND COVER ON EROSION AND SEDIMENT CONTROL
ON CONSTRUCTION SITES

Kinds of Ground Cover

Soil Reductions Related
to Bare Surfaces

Seedings1

Permanent grasses

99

Ryegrass (perennials)

95

Ryegrass (annuals)

90

Small grain

95

Millet or sudangrass

95

Grass sod

99

Hay (2 tons/acre)

98

GaSWCC (Amended - 2000)

Kinds of Ground Cover

Soil Reductions Related
to Bare Surfaces

Small grain straw

98

(2 tons/acre)

Corn stalks (4 tons/acre)

98

Woodchips (6 tons/acre)2

94

Wood cellulose fiber

90

(1 3/4 tons/acre)2

Fiberglass (1000 lbs/acre)2

95

Asphalt emulsion

98

(1250 gal/acre)

Other kinds of mulches that may be used are gravel,

stones, fiber matting and excelsior.

1 Values of seeded vegetation are based upon a fully established stand. 2 Based on research in progress. Reference: USDA, Agricultural Research Service.

STRUCTURAL CONSERVATION PRACTICES

In some instances, vegetative cover and mulches alone will not provide sufficient protection from the erosive forces of water. In such cases, alternate structural practices can be used to curb erosion and sedimentation during land-disturbing activities. These practices should be planned and employed in a practicable combination with vegetative and mulching measures.
Structural practices must be adequately designed and properly installed to accomplish the desired objective. Design should be based on the appropriate storm discharge and velocities. Consideration should be given to the damage potential, safety hazards, planned life and required maintenance of each individual structural practice.
Following is an overview of standards and specifications for structural practices contained in Chapter 6 of this Manual.
Cd - CHECKDAM

A small temporary barrier or dam constructed across a swale or drainage ditch. This is applicable for use in small channels which drain five (5) acres or less (not to be used in a live stream) in order to reduce erosion by slowing the velocity of concentrated storm water flows.
Ch - CHANNEL STABILIZATION

Improving, constructing or stabilizing a natural or artificial channel for conveying water flows. In certain instances on selected development, it will be found that

2-7

existing channels will not be adequate to convey desired discharges. New channels may be required to eliminate flooding. In many cases, existing channels cannot be considered stable. Therefore, this practice may be employed to assist in stabilizing these channels
Co - CONSTRUCTION EXIT
A stone-stabilized pad located at any point where vehicular traffic will be leaving a site onto a public right-ofway, street, roadway, or parking area. Its purpose is to reduce or eliminate transportation of soil (by motor vehicles) from the construction area onto public rights-ofway.
Cr - CONSTRUCTION ROAD STABILIZATION
Roads, parking areas, and other transportation routes that are stabilized with coarse aggregate between the time of initial grading and final stabilization. This travelway provides a fixed route for travel for construction traffic, reduces erosion, and subsequent regrading of permanent roadbeds, and provides a stable base for paving.
Dc - STREAM DIVERSION CHANNEL
A temporary channel that diverts a stream around a construction site to protect the streambed from erosion and allow work "in the dry". This diversion is used when in-stream work is unavoidable, as with linear projects such as utilities or roads that frequently cross and impact live streams and create a potential for excessive sediment loss by both the disturbance of the approach areas and by the work within the streambed and banks.
Di - DIVERSION
An earth channel with a compacted supporting ridge on the lower side, constructed above, across, or below a slope. The purpose of this practice is to reduce slope lengths, break-up concentrations of runoff and move water to stable outlets at non-erosive velocities. Diversions should be designed to discharge water into established disposal areas.
Dn1 - TEMPORARY DOWNDRAIN STRUCTURE
A flexible conduit of heavy-duty plastic or other material used as a temporary structure to convey concentrations of stormwater down the face of a cut or fill slope. Flexible downdrains are used on slopes where concen-

trations of stormwater would cause substantial erosion. They are removed once the permanent water disposal system is installed.
Dn2 - PERMANENT DOWNDRAIN STRUCTURE
A paved chute, pipe or a sectional conduit of prefabricated material designed to safely conduct surface runoff from the top to the bottom of a slope. Downdrain structures are to be used where concentrated water will cause excessive erosion of cut and fill slopes.
Fr - FILTER RING
A temporary stone barrier used in conjunction with other sediment control measures and constructed to reduce flow velocities and filter sediment. A filter ring can be installed at or a around devices such as inlet sediment traps, temporary downdrain inlets, and detention pond retrofits to provide additional sediment filtering capacity.
Ga - GABION
Large, rock-filled baskets wired together to form flexible monolithic building blocks. They are used in channels, retaining walls, abutments, check dams, etc., to prevent erosion and sediment damage to a specific structure.
Gr - GRADE STABILIZATION STRUCTURE
Structures of concrete, rock masonry, steel, aluminum, treated wood, etc. They are installed to stabilize the grade in natural or artificial channels and to prevent the formation or advance of gullies and to reduce erosion and sediment pollution.
Lv - LEVEL SPREADER
A temporary structure constructed with a flat grade across a slope where concentrated runoff may be intercepted and diverted onto a stabilized outlet. Concentrated flow of stormwater is converted to sheet flow at the level spreader.
Rd - ROCK FILTER DAM
A permanent or temporary stone filter dam installed across small streams and drainageways with a drainage area of 50 acres or less. This structure is installed to serve as a sediment-filtering device and to reduce storm water flow velocities.

2-8

GaSWCC (Amended - 2000)

Re - RETAINING WALL
A constructed wall of concrete, masonry, reinforced concrete, cribbing, treated timbers, gabions, stone dry wall, riprap or other durable material. They are installed to stabilize cut or fill slopes where maximum permissible slopes of earth are not obtainable. Each situation will require a specific design by a design engineer.
Rt - RETROFITTING
The physical modification of a storm water management outlet structure, using a half round corrugated metal pipe or similar device, to trap sediment contained in runoff water.
Sd1 - SEDIMENT BARRIER
A temporary structure constructed of silt fences, straw or hay bales, brush, logs and poles, gravel or other filtering materials. They are installed to prevent sediment from leaving the site or from entering natural drainageways or storm drainage systems. They are not to be used on high-risk areas or where there will be a possibility of failure. Formal design is normally not required for sediment barriers.
Sd2 - INLET SEDIMENT TRAP
Small temporary basins excavated around a storm drain inlet. They are employed to trap sediment in runoff water from small, disturbed areas. Cleanout of these facilities is normally required after each heavy rainfall.
Sd3 - TEMPORARY SEDIMENT BASIN
A basin created by an embankment or dam containing a principal spillway pipe and an emergency spillway. These structures are normally situated within natural drainageways and at the lowest point on a construction site and are used to trap sediment contained in runoff water. Excavated basins may be employed where sites for embankment do not exist. Sediment basins serve only during the construction phase and are removed from the site when the disturbed area has been permanently stabilized.
Structure size will vary depending on the size of the drainage area, volume of sediments to be trapped, rainfall, structure location, etc. These structures can be regarded as being hazardous if constructed in areas of dense population. In these cases, it is advisable to protect them from trespassing.
Permanent sediment basins are designed to fit into the overall plan of the completed development. They
GaSWCC (Amended - 2000)

may be converted to storm water retention facilities to reduce storm water discharges.
This specification does not apply to the design of permanent sediment basins.
Sr - TEMPORARY STREAM CROSSING
A temporary structure installed across a flowing stream or watercourse for use by construction equipment. The structure may consist of a pipe, bridge, or other suitable device permitting vehicular traffic without damaging stream banks and beds.
St - STORM DRAIN OUTLET PROTECTION
A paved or short section of riprap channel placed at the outlet of a storm drain system. The purpose is to reduce the velocity of water flows below storm drain outlets, and to prevent erosion from concentrated flow.
Su - SURFACE ROUGHENING
Providing a rough soil surface with horizontal depressions created by operating a tillage or other suitable implement on the contour, or by leaving slopes in a roughened condition by not fine grading them. This aids in the establishment of vegetation, reduction of runoff, and reduction of sediment.
Tp - TOPSOILING
Topsoiling areas to be vegetated by utilizing a suitable quality soil. The purpose is to provide a suitable soil medium for vegetative growth on areas where desired stands of vegetation are difficult to establish and maintain.
Wt - VEGETATED WATERWAY OR STORMWATER CONVEYANCE CHANNEL
Outlets for diversions, terraces, berms, or other structures. They may be natural or constructed, shaped to required dimensions and paved or vegetated for disposal of storm water runoff. They may be of two general cross sections: parabolic or trapezoidal. Parabolic waterways are the most commonly used. For waterways to be successful, it is essential that a protective cover of vegetation or other erosion protective measures be implemented. Flow velocities must be selected that will produce non-erosive flows within the waterway during peak discharges.
2-9

CONSTRUCTION TECHNIQUES
Other construction techniques may be employed by field personnel to assist in implementing an effective erosion control program. A few of these are discussed below.
a. Leave Exposed Soil Surfaces Rough. Smooth soil surfaces will erode more readily than rough ones. Therefore, cut or fill slopes should not be "dressed" or smoothed until time to establish vegetation. Cut or fill slopes may be scarified or serrated using conventional earth moving equipment to provide this roughening effect. The cleated tracks of bulldozers are effective in compacting as well as roughening cut or fill slopes.
b. Selective Fill Placement. Fills over culverts and conduits can be left in a condition to drain rain water to the upstream side of the culvert. This operation can be performed at the end of each construction day and will assist in retaining sediment on the site.
c. Selective Clearing. Clearing operations should be confined to the removal of timber and heavy brush only. Ground covers consisting of small plants, weeds and organic matter should be retained until the start of the grading operation.
d. Retain Natural Sediment Traps. Small depressions in the land surface, natural creek berms and other natural sediment traps may be preserved in a natural state until such time as building sequences will require their alteration.
e. Retention of Natural Vegetation. Natural Vegetation on disturbed area perimeters and adjacent to stream channels should be retained.
UNIFORM CODING SYSTEM
The following coding system chart has been developed to provide statewide uniformity for erosion and sediment control plans. A code has been assigned to each practice. This code should appear at the desired location on the plan. In some instances, more than one code will appear. For example, an area planted in temporary vegetation will eventually be established to permanent seeding. Therefore, both codes should appear on the plans at the appropriate location. A symbol also has been assigned to most practices. For certain practices it will be necessary to place both the symbol and code letter on the plans.
To assist the user, a small detail drawing and a brief description of the major characteristics of the practice have been included on the coding system chart.
2-10

GaSWCC (Amended - 2000)

GEORGIA
UNIFORM CODING SYSTEM
FOR SOIL EROSION AND SEDIMENT CONTROL PRACTICES
STATE SOIL AND WATER CONSERVATION COMMISSION OF GEORGIA

STRUCTURAL PRACTICES

CODE PRACTICE

DETAIL

MAP SYMBOL

DESCRIPTION

Cd

CHECKDAM

Ch

CHANNEL STABILIZATION

Co

CONSTRUCTION EXIT

Cr

CONSTRUCTION ROAD
STABILIZATION

Dc

STREAM DIVERSION CHANNEL

Di Dn1 Dn2 Fr

DIVERSION
TEMPORARY DOWNDRAIN STRUCTURE
PERMANENT DOWNDRAIN STRUCTURE
FILTER RING

Ga

GABION

Gr

GRADE STABILIZATION
STRUCTURE

Lv

LEVEL SPREADER

Rd

ROCK FILTER DAM

Re

RETAINING WALL

Rt

RETROFITTING

Sd1 SEDIMENT BARRIER

Sd2

INLET SEDIMENT TRAP

A small temporary barrier or dam constructed across a swale, drainage ditch or area of concentrated flow.

Improving, constructing or stabilizing an open channel, existing stream, or ditch.

Co
A crushed stone pad located at the construction site exit to provide a place for removing mud from tires thereby protecting public streets.
(Label)

A travelway constructed as part of a construction plan including

Cr

access roads, subdivision roads, parking areas, and other on-site

vehicle transportation routes.

Dc

A temporary channel constructed to convey flow around a

construction site while a permanent structure is being constructed.

An earth channel or dike located above, below, or across a slope to divert runoff. This may be a temporary or permanent structure.

Dn1
(Label)

A flexible conduit of heavy-duty fabric or other material designed to safely conduct surface runoff down a slope. This is temporary and inexpensive.

Dn2
A paved chute, pipe, sectional conduit or similar material designed to safely conduct surface runoff down a slope.

(Label)

Fr A temporary stone barrier constructed at storm drain inlets and pond outlets.

Rock filter baskets which are hand-placed into position forming soil stabilizing structures.

Gr
(Label)

Permanent structures installed to protect natural or artificial channels or waterways where otherwise the slope would be sufficient for the running water to form gullies.

A structure to convert concentrated flow of water into less erosive sheet flow. This should be constructed only on undisturbed soils.

A permanent or temporary stone filter dam installed across small streams or drainageways.

Re
(Label)

A wall installed to stabilize out and fill slopes where maximum permissible slopes are not obtainable. Each situation will require special design.

A device or structure placed in front of a permanent stormwater

Rt

detention pond outlet structure to serve as a temporary sediment

filter.

(Label)

TYPE (Indicate type)

A barrier to prevent sediment from leaving the construction site. It may be sandbags, bales of straw or hay, brush, logs or poles, gravel, or a silt fence.

An impounding area created by excavating around a storm drain drop inlet. The excavated area will be filled and stabilized on completion of construction activities.

CODE PRACTICE

DETAIL

MAP SYMBOL

DESCRIPTION

Sd3

TEMPORARY SEDIMENT BASIN

Sr

TEMPORARY STREAM CROSSING

St

STORM DRAIN OUTLET

PROTECTION

A basin created by excavation or a dam across a waterway. The surface water runoff is temporarily stored allowing the bulk of the sediment to drop out.
Sr
A temporary bridge or culvert-type structure protecting a stream or watercourse from damage by crossing construction equipment.
(Label)
St A paved or short section of riprap channel at the outlet of a storm drain system preventing erosion from the concentrated runoff.

Su

SURFACE ROUGHENING

A rough soil surface with horizontal depressions on a contour or

Su

slopes left in a roughened condition after grading.

Tp Wt

TOPSOILING
VEGETATED WATERWAY OR STORMWATER CONVEYANCE
CHANNEL

The practice of stripping off the more fertile soil, storing it, then

Tp

spreading it over the disturbed area after completion of construction

(Show Striping activities.
& Storage Areas)

Paved or vegetative water outlets for diversions, terraces, berms, dikes or similar structures.

VEGETATIVE MEASURES

Bf

BUFFER ZONE

Cs Ds1 Ds2 Ds3 Ds4

COASTAL DUNE STABILIZATION (WITH
VEGETATION)
DISTURBED AREA STABILIZATION (WITH MULCHING ONLY)
DISTURBED AREA STABILIZATION
(WITH TEMPORARY SEEDING)
DISTURBED AREA STABILIZATION
(WITH PERMANENT VEGETATION)
DISTURBED AREA STABILIZATION (WITH SODDING)

Bf
(Label)

A strip of undisturbed original vegetation, enhanced or restored existing vegetation or the reestablishment of vegetation surrounding an area of disturbance or bordering streams.

Cs

Planting vegetion on dunes that are denuded, artificially

constructed, or re-nourished.

Establishing temporary protection for disturbed areas where

Ds1

seedings may not have a suitable growing season to produce an

erosion retarding cover.

Establishing a temporary vegetative cover with fast growing

Ds2

seedings on disturbed areas.

Ds3

Establishing a permanent vegetative cover such as trees, shrubs,

vines, grasses, sod, or legumes on disturbed areas.

A permanent vegetative cover using sods on highly erodible or

Ds4

critically eroded lands.

Du

DUST CONTROL ON DISTURBED AREAS

Controlling surface and air movement of dust on construction site,

Du

roadways and similar sites.

Mb

EROSION CONTROL MATTING AND BLANKETS

The installation of a protective covering (blanket) or soil stabilization

Mb

mat on a prepared planting area of a steep slope, channel, or

shoreline.

Pm Sb

POLYACRYLAMIDE (PAM)
STREAMBANK STABILIZATION (USING PERMANENT VEGETATION)

Tb

TACKIFIERS AND BINDERS

Pm

The land application of product containing anionic polyacrylamide

(PAM) as temporary soil binding agents to reduce soil erosion.

The use of readily available native plant materials to maintain and

Sb

enhance streambanks, or to prevent, or restore and repair small

streambank erosion problems.

Tb

Substance used to anchor straw or hay mulch by causing the

organic material to bind together.

STATE SOIL AND WATER CONSERVATION COMMISSION OF GEORGIA

GaSWCC (Amended - 2000)

CHAPTER 3
PLANNING AND PLANS
SECTION I - PLANNING
Planning is the critical process by which land-disturbing activities are formulated. The planning process for activities governed by Act 599 can be broken down into the following four progressive stages:
1. preliminary site investigations 2. preliminary design 3. subsurface investigation 4. final design
For many small land-disturbing activities, steps one and two are sometimes combined but planning for major developments normally follows these three steps. The Erosion and Sedimentation Act of 1975 does not change this planning process. It merely states that erosion and sediment control planning should be included as one of the major considerations.
To be successful, a plan must include measures for efficient scheduling and coordination of construction activities and provisions for the maintenance of conservation practices. Stormwater management facilities should be included to reduce the impact of stormwater runoff to on-site facilities both during and after construction is completed. It is desirable to include stormwater retention structures. Land-disturbing activities normally will result in an increase in runoff from the site. Stormwater management structures will reduce the impact of damages on downstream facilities resulting from an increase in runoff.
PLANNING STAGES
Preliminary Site Investigation Stage. The first consideration in the preliminary site investigation stage should be the assimilation of all available resource information. This information will assist the planners in identifying critical physical features of the site which would have significant impact on erosion and sediment control. Delineation of flood-prone areas and areas which would have a high aesthetic value if protected can be identified. Sources of resource information are included in Chapter 5 of this handbook.

A conservation planning base map should be prepared utilizing all information available. The final step would be a detailed on-site inspection. At this time, base maps should be thoroughly checked for accuracy.
Preliminary Design Stage. In the preliminary design stage, a thorough analysis of the information assembled during the preliminary site investigation stage should be accomplished. The objective of the analysis is to determine how the proposed site can be best utilized as intended without causing undue harm to the environment. Areas particularly vulnerable to erosion and sedimentation because of existing topography, soils, vegetation or drainage should be identified. The planner is encouraged to use available soils information in his site analysis. A discussion of the use of soils information in site planning follows in this chapter.
Subsurface Investigation Stage. A subsurface investigation should be accomplished to determine the geological features and the nature and properties of the soils present on the site. A detailed on-site soils investigation will be necessary for the design of complex buildings, roadways, and other engineering structures. Facilities which will be serviced by septic tank will require on-site testing. The stability of slopes should be determined based on soils analysis. Groundwater problems should be identified at this time. Soils subject to water flows should be analyzed for permissible velocities. Soils to be established in vegetation should be examined for pH, nutrient levels and ease of establishing vegetation. Methods of overcoming soils limitations should be explored.
Final Design Stage. Final designs should be based on detailed engineering surveys, subsurface investigations and sound conservation and engineering principles. Permanent buildings, roadways and engineering structures should be fitted to the topography and soil types. Efficient, durable and easily maintained erosion control measures should be employed. Sediment basins, barriers and traps should be designed to trap sediment which would be transported from the site. All stormwater facilities should be of adequate capacity and have the ability to withstand peak velocities. Filling or development within flood-prone areas should be avoided except those activities necessary to promote public health and welfare. If, for example, roadway crossings are made, openings must be sized to eliminate undue restriction in water flows and excessive downstream velocities. Natural vegetation and open space should be provided. Finally, rigid construction scheduling should be employed.

GaSWCC (Amended - 1995)

3-1

Figure 3-1. - Soils information is a valuable tool in planning for land-disturbing activities.
SOILS INFORMATION AND SITE PLANNING
An invaluable tool in planning for land disturbing activities is soils information available through Georgia Soil and Water Conservation Districts. The USDA Natural Resources Conservation Service soil scientists study, evaluate, classify and map soils in counties throughout Georgia and publish soil surveys with maps and descriptions. This soils information can be related to local plat maps to identify kinds of soils in a specific area. The map on page 3-5 shows the status of soil survey publications in Georgia. If unpublished, arrangements can possibly be made through local Soil and Water Conservation Districts to examine available soils maps and to obtain additional soil information for the proposed land-disturbing activity.
Soil maps and supporting data provide information about important soil properties, including the following:
Flood Hazards - Soil surveys show areas that are subject to flooding. Although this information is not a substitute for hydrologic surveys, which determine the limits of flooding on the basis of the severest flood expected once in 10, 25, 50 or 100 years, it does provide a good first approximation of the flood-prone areas.
3-2

Wetness - Soil surveys show if the soil is well drained, poorly drained, or seasonally waterlogged, and if the water table is seasonally high. The rating of the permeability of soils is also included.
Bearing Capacity - Soil surveys provide test data and estimates of the physical properties of soils that enable engineers to make sound judgments about bearing capacities for shallow foundations. Major soil layers to a depth of about 5 feet are classified in both the United and the AASHTO systems. Data is also given on grainsize distribution and expansiveness for each soil layer.
Depth to Rock - Soil surveys show locations where bedrock is at depths of less than 5 or 6 feet and describe the geologic material that underlies the soil.
Shrink-swell and Slippage - Soil properties that result in high swelling pressures, mainly the kind and amount of clay, are given in soil surveys. Soil surveys also indicate soil properties that make soils unstable and susceptible to slippage.
THE UNIVERSAL SOIL LOSS EQUATION
The properties that affect the erodibility of the soil are of particular interest in planning for the reduction of soil erosion and sedimentation. The erodibility of Georgia soils has been calculated.
The soil erodibility factor (k factor) is one of the variables in the Universal Soil Loss Equation. It will yield an estimate of the annual soil loss for a site in tons per acre. The equation is:
Soil Loss = RKLSCP
Where R = rainfall factor K = soil erodibility factor LS = slope length and steepness C = vegetative cover P = support practice factor
A detailed discussion of the equation is contained in Appendix B-2 of this Manual.
To assist the user in the interpretation of soils for landdisturbing activities, a table of estimated soil properties for Georgia soils has been completed and is contained in Appendix B-1. Estimated soil properties are included for permeability, soil reaction (pH), shrink-swell potential, corrosivity, depth to water table and bedrock, flood frequencies, and hydrologic soil groupings. Soil limitation ratings for septic tank absorption fields, sewage lagoon areas, shallow excavations, dwellings and small commercial building, and local roads and streets have
GaSWCC (Amended - 1995)

also been included. Planners are encouraged to use this material in evaluating the suitability of tracts of land for specific developments.
Additional soils information for site planning can be obtained during the subsurface investigation phase of planning. For example, the K values of the soils in Appendix B-1 of this manual are estimates for the surface layer of the soil. Because this value will differ at varying depths of the soil profile, planners of land-disturbing activities should specify that the estimated erodibility of subsurface soil be obtained during site borings.
SECTION II - PLANS
Following are examples illustrating methods used in the preparation of erosion and sediment control plans. The set of drawings is intended to demonstrate a methodology for the preparation of an erosion and sediment control plan for a land-disturbing activity.
It should be emphasized that the methodology utilized in this example is only one of many available to the designer or planner. Many other practical combinations of erosion control measures could have been employed to effectively reduce erosion on this site.
LAND DISTURBING ACTIVITY PLAN
The set of drawings for the proposed land disturbing activity are intended to illustrate a method for the preparation of plans for a phased development. Hypothetically, the owner has requested that the consulting engineering firm prepare a plan for a 105-acre development that will be constructed in two phases. The first phase will consist of a parcel of land to be developed into a public school facility. Phase two will consist of a single family residential development. Initially, the engineering firm is to select approximately 21 acres from the total tract of land. This first phase is then to be planned for the public school facility. The remaining acreage will be developed at a later date.
The first step that the engineering firm has undertaken is to prepare a detailed boundary line sketch for the total tract of land (See Drawing 1). On this sketch, all major roadways, watercourses, soils and vegetative information have been imposed.
Information on the soils, slope and drainage patterns was obtained from a soils map of the county. Vegetative

information was obtained from a field reconnaissance survey of the site. A soils information chart was added to the drawing using soils information from Appendix B1 of this manual. Each soil series was then shaded on the drawing to effectively illustrate the soils limitations of the site. A zoning sketch obtained from county zoning maps and a site location sketch obtained from the soil survey map were added to the drawing.
An analysis of the combined soils, vegetation and drainage drawing indicated that the portion of the total development which can best support a development requiring extensive grading is located in the northwest portion of the overall tract, on soils with the symbol GeB2, Gwinnett Clay Loam. This portion of the tract would permit an intensive development with a minimum of clearing, grading and potential erosion. After analysis, conclusions were obtained from Drawing Number 1 and a detailed boundary line survey and a topographic map was then completed for the phase one development (See Drawing 2).
All fixed improvements including the school buildings, gymnasium, football field, playground area, and roadways were then located on the topographic map in a manner which would reduce disturbed areas and avoid the steeper, more erodible slopes.Volumes of earth work were reduced as much as possible by balancing the cut from the school and parking area with the fill required for the football field. Cuts and fills for the playground area and roadway were carefully balanced. As much vegetation as practical was preserved and protected as planned.
After determining the location of proposed fixed improvements, the next step was to plan for the installation of stormwater management and erosion control measures (See Drawing 3). The final erosion and sediment control plan contains combinations of vegetative measures and structural erosion and sediment control practices which should conform to the requirements of the law, and effectively reduce erosion from the landdisturbing activity site. Sediment retention structures have been added to reduce the probability of sediment leaving the site. A timing schedule was developed and has been included on the drawing.
It should be emphasized again that there are numerous methodologies, techniques, and combinations of erosion and sediment control practices which could have been employed in this example.

GaSWCC (Amended - 1995)

3-3

3-4

GaSWCC (Amended - 1995)

U.S. Department of Agriculture

Natural Resources Conservation Service

Legend
Modern Published Soil Survey (1966 or newer)

Tennessee

North Carolina

Old Published Soil Survey (1966 or newer)

Whitfield Habersham

Dade Catoosa

Fannin Murray
Gilmer

Union Towns

Rabun

White

Modern Soil Survey with field mapping complete, to be published

Alabama Clayton NeRwotcokndale MorgWaaltnon

Walker Chattooga

Gordon (1)

Pickens

Floyd

Bartow Cherokee

Polk Haralson

Cobb Paulding

Lumpkin

Stephens

Dawson

Hall

Banks Franklin Hart

Forsyth

Jackson

Madison

Elbert

(1)

Barrow

Gwinnett

OcCoAlnatehrkeeens

Oglethorpe

Modern Soil Survey being conducted, with completion date set
Mapping and publication plans incomplete
Soil Survey update in progress (1) Interpretation update available

South Carolina
McDuffie

D(1o)uglas

Atlanta
(1)

Dekalb

Greene (2)

Wilkes Lincoln Teliaferro

Carroll Heard
Troup

Fulton Fayette

Henry

Coweta

Spalding

Meriwether Pike

Butts Monroe

Lanier Upson

Putnam

Jasper Jones

Baldwin

HanWcaoschkingtonWGalrarsecnoJcekfferson

CoRluicmhmbAiaoungdusta Burke

Bibb

Wilkinson

Jenkins

Harris

Talbot

Crawford Macon

Johnson

Emanuel

(2) Interim report available Soil Survey update completed

Taylor

Muscogee
Marion Chcahtteaehoo-

Stewart

Schley Sumter

Webster

Quitman Randolph Terrell Lee

Pe(1ac)h

Macon

(1) Houston

Dooly

TBwl(ei2gcg)ksley Dodge

Pulaski

Crisp

Wilcox

Turner

Ben Hill

Laurens
(1) Treutlen

BuSllocrcehven Chandler

Montgomery

Bryan

Telfair

Wheeler Jeff Davis

Evans

Toombs

Tattnall

Appling

Long

Liberty

Wayne

Effingham
Savannah
Chatham

Clay Early

Calhoun Dougherty
Albany
Baker

Miller Mitchell
Seminol Decatur Grady

Irwin Tift

Worth Colquitt

Berrien

Bacon

Coffee Atkinson Ware

Pierce

Thomas

Cook

Lanier Clinch

Brooks Lowndes

Charlton

McIntosh Brantley Glynn
Camden

Atlantic Ocean

Valdosta Echols

Florida

Source: Information provided by NRCS field personnel. Natural Resources Conservation Service, Athens, GA 1997

STATUS OF SOIL SURVEYS

GEORGIA

December 1997

0

25

50

75

100 miles

20 0 20 40 60 80 100 kilometers
Scale is approximate

SITE LOCATION SKETCH

Drawing 1

GeE2

Soils, Vegetation, and Drainage

U.S. HWY 76
53 MCOILNECSOTROD

PHASE I

1.L2EMXIILNEGSTTOON

Y 6O7RKMITLOEWSNTO INDEPENDENCE DRIVE
DEER CREEK

0

1320

SCALE, IN FEET

2F4RMAINLKELSINTO

PHASE II
WASHINGTON ROAD

1.L2EMXIILNEGSTTOON

LEGEND

STREAMS Perennial
Intermittent PROPERTY LINE POWER LINE TELEPHONE LINE SOIL BOUNDARY SOIL SYMBOL VEGETATION

CYC2
TYPE

ZONING SKETCH
AU AGRICULTURAL, URBAN C COMMERCIAL RI RESIDENTIAL OI OFFICE, INSTITUTIONAL

C

AU C

RI

C

OI

RI

AU C
AU

C

RI

GaSWCC (Amended - 1995)

GeB2
N
GeB2
BROOMSEDGE

INDEPENDENCE DRIVE

U.S. HWY 76

Cfs

MIXED HARDWOOD 18-36" &
PINE 12-20"
GeB2
BROOMSEDGE

CYC2

GeC2

CYB2

MIXED HARDWOOD 18-36" &
PINE 12-20"

GeC2
SMALL PINES 4-8"

ALDERS &
SMALL WILLOWS

N
Cfs GeC2

SOILS INFORMATION

SOIL SYMBOL

NAME

Cfs

CHEWACLA

CYB2 CECIL SANDY LOAM

SLOPE %

K

LIMITATION

SYMBOL

REASONS FOR LIMITATIONS

0 2 .32 SEVERE

VERY FREQUENT FLOODING HIGH SEASONAL WATER TABLE

2 6 .32 SLIGHT

GeB2 GWINNETT CLAY LOAM

2 6 .28 SLIGHT

GeC2 GWINNETT CLAY LOAM

6 10 .28 MODERATE

GeE2 GWINNETT CLAY LOAM

10 25 .28 SEVERE

MiC2 MADISON SANDY CLAY LOAM

MiD2

MADISON SANDY CLAY LOAM

6 10 .32 MODERATE 10 15 .32 SEVERE

SLOPES
SLOPES SLOPES, MODERATE SHRINKSWELL POTENTIAL SLOPES

Seal

Certification

MiC2 MiD2

SMALL PINES 4-8"
MiB2

DEER CREEK

ALDERS &
SMALL WILLOWS

WASHINGTON ROAD

MiC2
105 Acres

GeE2

Cfs

100 0 100 200 300 SCALE, IN FEET

INDEPENDENCE DEVELOPMENT

BILL PENN CONSULTING PLANNERS AND ENGINEERS

OWNER

COUNTY, STATE

G. WASHINGTON

GWINNETT, GEORGIA

DRAWN BY TOM JEFFERSON

LAND LOT 200

DATE JULY 4, 1990

LAND DISTRICT 26th

3-7

820 864.51

SITE LOCATION SKETCH

L1.E2XIMNILGTESONTO

N

DEER CREEK

C5O3 NMCILOERSDTO

U.S.

PHASE
HWY 76

I

PHASE II

ENDENCE DRIV

WRASOAHIDNGTON

67 MILES TO YORKTOWN

INDEP E

0

1320

SCALE, IN FEET

FR2A4NMKILLIENS TO

LEGEND

L1.E2XIMINLGETSOTNO

EL=808.91

S 500540'5.061"E' 800

810

810

820

S41 16 00"W 300.26'

830 840
EL=845.92
850

N 41 16'00"E 1088.09'

860

9S185.0031'3'00"

800 810 820 R=1738671.3.311' "
PARKING FIN. FSLCOHOOROELLEV. 847.00
GE8YL4ME7V.0. 0 PARKING

790
PLEALYEGVR. 8O1U2N.0D0 AREA

4S086.05323'00"W

N
4S077.2523''10"E

Drawing 2 Detailed Boundary Line and Topographic Survey With Fixed Improvements

790 800 810

S2090'.2070'00"E

IRON PIN FOUND PROPERTY LINE TEMPORARY BENCH MARK POWER LINE TELEPHONE LINE CONTOUR LINE, EXISTING CONTOUR LINE, FINISH

EL=864.41

860N21026.1204' '00"W EL=855.33

FEOLEOVT.B8A5L8L.0F0IELD
857.00 N27942.430'00"W

NOTE: SLOPE PARKING LOT AREA TO DRAIN AWAY FROM MAIN SCHOOL BUILDING ON 1.0% GRADE AND TOWARD CENTERLINE OF LOT ON 0.5% GRADE
CROWN FOOTBALL FIELD 1.5 FEET AT CENTER
SLOPE PLAYGROUND AREA TO DRAIN TOWARD CENTERLINE ORIENTED NORTH-SOUTH

GaSWCC (Amended - 1995)

810 820 830

840 850

TOTAL AREA = 21.34 ACRES

100 50 0

100

200

SCALE, IN FEET

Seal

Certification

INDEPENDENCE DEVELOPMENT

BILL PENN CONSULTING PLANNERS AND ENGINEERS

OWNER

COUNTY, STATE

G. WASHINGTON

GWINNETT, GEORGIA

DRAWN BY TOM JEFFERSON

LAND LOT 200

DATE JULY 4, 1990

LAND DISTRICT 26th

3-9

SITE LOCATION SKETCH

L1.E2XIMNILGTESONTO

N

DEER CREEK

C5O3 NMCILOERSDTO

PHASE
U.S. HWY 76 I

PHASE II

ENDENCE DRIV

WRASOAHIDNGTON

67 MILES TO YORKTOWN

INDEP E

0

1320

SCALE, IN FEET

FR2A4NMKILLIENS TO

LEGEND
IRON PIN FOUND PROPERTY LINE TEMPORARY BENCH MARK POWER LINE TELEPHONE LINE CONTOUR LINE, EXISTING CONTOUR LINE, FINISH CLEARING LIMIT LINE

L1.E2XIMINLGETSOTNO

EL=808.91

S 500540'5.061"E' 800

810

810

820

Co

S41 16 00"W 300.26'

Ds3 St
830
Cd
840 EL=845.92
Cd
850

N 41 16'00"E 1088.09'

860
Cd
EL=864.41

Di Cd
Tp
Di

206.10' 860

EL=855.33

820

Mb

Drawing 3

Erosion and Sediment

810 820

Sd3

R=1738671.3.311' "

Di

790 800
Lv

N
BRBUASRHRIERSd4S1077.2523''10"E

Di Ds2PLEALYEGVR. 8O1U2N.0D0 AREA
Ds3

790 800

Control Plan
CONSTRUCTION SCHEDULE

4S086.05323'00"W

PARKING FIN. FSLCOHOOROELLEV. 847.00
GE8YL4ME7V.0. 0 Cr PARKING Sd2

Di
SEDIMENT FENCE Sd1
Ds3 Ds2

Tp

810

Lv

S2090'.2070'00"E

1991

1992

APR

MAY

JUNE JULY

AUG SEPT

OCT

APR

MAY

TIMBER SALVAGE ROAD, ROUGH GRADE
SEDIMENT CONTROL STRUCTURES CLEARING EROSION CONTROL STRUCTURES TOPSOIL STRIPPING and STORING LAND GRADING TEMPORARY VEGETATION
FOUNDATION and BUILDING CONSTRUCTION PAVING
PERMANENT VEGETATION REMOVE TEMPORARY STRUCTURES

9S185.0031'3'00"

St

Di

FEOLEOVT.B8A5L8L.0F0IELD

Ds2

Ds3

N27942.430'00"W

Wt
Dn2 Di
840 850
Mb

St
810
Sd3
820 830

TOTAL AREA = 21.34 ACRES

100 50 0

100

200

SCALE, IN FEET

Seal

Certification

NOTE: SLOPE PARKING LOT AREA TO DRAIN AWAY FROM MAIN SCHOOL BUILDING ON 1.0% GRADE AND TOWARD CENTERLINE OF LOT ON 0.5% GRADE
CROWN FOOTBALL FIELD 1.5 FEET AT CENTER
SLOPE PLAYGROUND AREA TO DRAIN TOWARD CENTERLINE ORIENTED NORTH-SOUTH

LOCATION

VEGETATIVE PLAN SPECIES

DATE

Football Field &

Playground

Hulled Common Bermudagrass

Roadside

Hulled Common Bermudagrass & Virgata Lespedeza

April '92 April '91

Waterway School

Sod Common Bermudagrass Ryegrass

April '91 Oct. '91

INDEPENDENCE DEVELOPMENT

BILL PENN CONSULTING PLANNERS AND ENGINEERS

OWNER
G. WASHINGTON

COUNTY, STATE
GWINNETT, GEORGIA

DRAWN BY
TOM JEFFERSON

LAND LOT
200

DATE
JULY 4, 1990

LAND DISTRICT
26th

GaSWCC (Amended - 1995)

3-11

EXAMPLE NARRATIVE DESCRIPTION OF A LAND-DISTURBING ACTIVITY PLAN (Fictional)
DESCRIPTION: Phase I of this proposed development is located on Hwy. 76, 1.2 miles west of Lexington, Georgia, and contains 21.34 acres. This area will be developed for use as a public school facility. Improvements will consist of a 28,800-square-foot school building, a 13,500-square-foot gymnasium, .88 acres of parking, a football field, a one-acre playground, and service roads. Phase II, which comprises approximately 83.7 acres, will contain single family residences and will be developed at a later date.
ZONING: The present zoning classification of Phase I is Office-Institutional (O-I). (See zoning sketch of Drawing Number 1 for zoning classifications of adjacent properties.)
DATES OF CONSTRUCTION: Initial construction is scheduled to begin April 1, 1991. Final stabilization should be accomplished before May 15, 1992.
SOILS, TOPOGRAPHIC AND DRAINAGE INFORMATION: (For soils, topographic and drainage information, see Drawing Number 1.)
VEGETATION: (For a description of existing vegetation, see Drawing Number 1.) All marketable timber will be salvaged. Top soil will be salvaged, stockpiled and spread on areas to be vegetated. Trees outside of the clearing line will be protected from damage by appropriate markings. (See Drawing Number 1 for clearing information and vegetative plan.) Supplemental vegetation will be established.
BUFFER REQUIREMENTS: An undisturbed natural vegetative buffer of 25 feet measured from the stream banks (100 feet measured horizontally, adjacent to trout streams) shall normally be retained adjacent to any state waters except where otherwise required by Part 6 of Article 5 of Chapter 5 of this title, the "Metropolitan River Protection Act," or by the department pursuant to Code Section 12-2-8, or when the economic use and the contour of the land require a different buffer subject to the division's approval, or where a drainage structure must be constructed, provided that adequate erosion control measures are incorporated in the project plans and specifications are implemented.
EROSION CONTROL PROGRAM: Clearing will be kept to an absolute minimum. Vegetation and mulch will be applied to applicable areas immediately after grading is completed. Gravel will be applied to parking areas and roadways as soon as grading is completed. Land-disturbing will be scheduled to limit exposure of bare soils to erosive elements. Storm water management structures will be employed to prevent erosion in areas of concentrated water flows. Erosion at the exits of all stormwater structures will be prevented by the installation of storm drain outlet protection devices.
SEDIMENT CONTROL PROGRAM: Sediment control will be accomplished by the installation of two sediment basins, approximately 550 linear feet of sediment fences and 375 feet of temporary brush barriers. Diversions will be installed to divert sediment laden runoff into the sediment basins and to protect cut and fill slopes from erosive water flow. A temporary construction exit will be employed to prevent the transport of sediment from the site by vehicular traffic.
STANDARDS AND SPECIFICATIONS: All designs will conform to and all work will be performed in accordance with the Standards and Specifications of the publication entitled, Manual for Erosion and Sediment Control in Georgia. (See attached calculations).
SAFETY PROTECTION: Construction activities will be performed in compliance with all applicable laws, rules and regulations. Sediment basin number II, which will be converted to a storm water detention structure, will be posted and fenced to exclude children.
MAINTENANCE PROGRAM: Sediment and erosion control measures will be inspected daily. Any damages observed will be repaired by the end of that day. Cleanout of sediment control structures will be accomplished in accordance with the specifications and sediment disposal accomplished by spreading on the site. Sediment basins and barriers will remain in place until sediment contributing areas are stabilized. The sediment basin, sediment fences, and the barriers will then be removed and the areas occupied by these structures vegetated. Sediment from the detention basin will be removed and this basin converted to a storm water detention structure. Guidelines for the maintenance of established vegetation will be provided to the owner when all disturbed areas are stabilized.

GaSWCC (Amended - 1995)

3-13

24-HOUR CONTACT PERSON: The telephone number of a person responsible for the project's erosion and sediment control program must be provided.

3-14

GaSWCC (Amended - 1995)

CHAPTER 4
LOCAL PROGRAMS: PRINCIPLES AND PROCESSES
The Erosion and Sedimentation Act of 1975 states that the governing authority of each county and municipality shall adopt a comprehensive ordinance establishing procedures governing land-disturbing activities conducted within their respective boundaries.
If counties and municipalities have failed to have in effect an ordinance conforming to the provisions of the law, then the State Board of Natural Resources will adopt appropriate rules and regulations governing activities within those areas.
The emphasis of the law is truly on implementation of local erosion and sediment control programs. It has been said that, "Unquestionably, local officials have the constitutional authority to make decisions concerning the use and allocation of local land and water resources. Also an erosion and sediment control program constitutes a segment of soil and water resources management which ought to be the responsibility of elected officials at the local level."(21)
PRINCIPLES
For any erosion and sediment control program to become effective, there are certain principles which should be applied for maximum effectiveness.
1. Erosion and sediment control should become a stated policy of all concerned, including public and private agencies operating in or having jurisdiction within the boundaries of the unit of government. It is imperative that developers, owners of land to be developed, their designated consultants, planners and engineers become aware of the necessity for sound erosion and sediment control programs.
2. A well-planned public information and education program on erosion and sediment control is essential for public and private support.
3. Competent technical personnel knowledgeable in local soil and climatic conditions, workable procedures, and inspections are necessary for successful erosion and sediment control.
GaSWCC (Amended - 1995)

4. To be effective, provision for erosion and sediment control must be made in the planning stage. Practical combinations of the basic design principles contained in Chapter 2 should be skillfully planned and applied in a timely manner.
5. Research observations and evaluations should be conducted to provide needed information for improvement of the erosion and sediment control program. A comprehensive review and evaluation of the overall sediment and erosion control program should be conducted at least every few years.
PROCESSES
An erosion and sediment control program may be subdivided into four basic processes:
a. ordinance development and implementation b. plan preparation and review c. inspection and enforcement d. information, education and training
ORDINANCE DEVELOPMENT AND IMPLEMENTATION
Local officials have a working knowledge of local conditions and problems. It is they who can best implement ordinances which take local needs into account.
In the past, the cost of correcting expensive sediment damages has often been the responsibility of local units of government. Therefore, it is advisable that local governments have direct control over the enforcement of laws pertaining to erosion.
Although the direct responsibility for drafting ordinances falls on local officials, citizen participation should be encouraged to insure that the final product will reflect their needs and wishes.
A model ordinance has been developed by the State Soil and Water Conservation Commission for use by officials in municipalities and counties. The model is intended primarily to provide guidelines for control of urban soil erosion and sediment pollution. It is designed to meet state requirements for establishing programs as required in Act 599. A copy of the model is contained in Appendix D of this manual.
Preceding the body of the model ordinance is a brief explanation of the contents. This explanation is intended to clarify certain sections or phrases contained in the model. Opinions expressed therein are not necessarily requirements to be fulfilled. Local authorities may wish
4-1

to develop individual ordinances from the wealth of comprehensive material available for this, or they may utilize another of the models available. Regardless of the method used, the contents of the model ordinance should be tailored to fulfill specific needs of the local governing authority. A review of the final draft by the county or city attorney should be mandatory.
The adoption of an ordinance should be considered as only the first step toward a sound soil erosion and sedimentation control program. It is essential that sufficient lead time be provided for education of the public and technical training of persons directly involved in its full implementation.
PLAN PREPARATION AND REVIEW PROCESS
All parties involved in the plan development and review process must realize without exception that there is more than one approach to minimizing erosion and sedimentation damages. Flexibility without compromising the primary objective must be encouraged to arrive at a common solution to erosion and sediment control problems on any given site. All available resources should be explored. Local officials should plan to provide assistance to the developer and his consulting planners and engineers prior to plan submission before plan processing can be effective. Assistance from federal and state agencies having expertise in the field of soil and water conservation should be provided to the developer and his consultant. Developers may benefit by entering into an agreement for assistance through their Soil and Water Conservation District. Technical expertise can then be provided by federal and state agencies.
The erosion and sediment control plan should be submitted as early in the planning stage as possible. The plan itself should embrace all aspects of the requirements of the basic design principles as specified in Chapter 2 of this manual. In addition, practical combinations of vegetative and structural conservation practices should be designed in accordance with the minimum requirements of the Standards and Specifications contained in Chapter 6.
It is recommended that the plan review process be broken down into the preliminary planning phase and the final design phase to reduce costly engineering fees. Such fees are normally considerably higher than preliminary planning fees. Costs for changes to engineering drawings and specifications can be prohibitive. An early, or first phase, submission of erosion and sediment control plans will promote general agreement and cooperation and provide for changes with minimum delay to the development process.

The responsibility for plan reviews has been delegated by Act 599 to the Soil and Water Conservation Districts. This does not relieve the county or municipality, however, from a responsibility to assure that plans conform to other local regulations and ordinances.
PLAN PROCESSING
Following is a recommended procedure for preparation and processing of an erosion and sediment control plan:
1. The owner, developer, or the authorized agent for either the owner or the developer, prepares the erosion and sediment control plan. The plan is prepared in accordance with the minimum requirements and recommendations contained in the Manual for Erosion and Sediment Control. (The manual should be incorporated by reference in the local erosion and sediment control ordinance.) Plans should be prepared only after consultation with the local governing authority, the Soil and Water Conservation District, and other agencies or individuals having expertise in the field of soil and water conservation.
2. The owner, developer, or the authorized agent for the owner or developer, submits the plans to the local permit-issuing authority after completing an application for a permit. (Local officials should determine the number of copies of plans and applications to be submitted by the owner, etc. It is suggested that a minimum of three copies of the plan be submitted.) If an application form has not been developed by the local unit of government, a letter of transmittal containing the following information should accompany the plans.
a. The name, address and phone number of the applicant.
b. The name, address and phone number of the land owner of record.
c. The name, address and phone number of the person responsible for carrying out the plan.
d. The name, address and phone number of the person preparing the plan.
e. The location of the activity including land lot and tax map page numbers.
f. Any other information as determined by the local unit of government.
The local unit of government may require that a preliminary erosion and sediment control plan be submit-

4-2

GaSWCC (Amended - 1995)

GaSWCC (Amended - 1995)

Land Disturbing Activity Application and
Permit Procedure
Land Disturber

Submit Plan &
Application with Appropriate Variances

Revise & Resubmit Plan

Maximum of 45 Days

Permit Denied

Permit Issued

Local Issuing

MOA exists

Authority/EPD
MOA does not exist

Issuing Authority Reviews
Plan

Plan Approved/Denied

Plan Approved/Denied

Soil and Water Conservation Districts

Technical Review By

Soil Conservation Service

MOA = Memorandum of Agreement

or State Soil and Water Conservation Commission

4-3

ted along with a preliminary site plan. The preliminary erosion control plan should not be cluttered with detailed erosion and sediment measures but should include the following information:
a. soil boundaries of all major soil series.
b. approximate limits of grading.
c. tentative measures for sediment and erosion control.
d. phasing of development to minimize area and duration of exposure of soils to erosive elements.
It is suggested that the governing authority of the county or municipality delegate the authority for receiving applications and processing permits to the county engineer, director of public works or other qualified individuals knowledgeable in the processing of site development plans. If in the ordinance the responsibilities of the governing authority are delegated to the constitutional or statutory local planning and zoning commission, then it is suggested that the plans and applications be processed by the director of the planning and zoning commission.
3. Two copies of the erosion and sediment control plan shall be forwarded as soon as possible to the local Soil and Water Conservation District, or its delegated authority, for review. In determining the adequacy of the plan, the district officials (supervisors) will be guided by the requirements and recommendations contained in the local manual. District supervisors may request the assistance from the erosion and sediment control specialist with the State Soil and Water Conservation Commission, specialists from the district or technical personnel of the Natural Resources Conservation Service. The district supervisor, after consultation with the district board, will forward the plans and recommendations to the permit-issuing authority of the municipality or county. These recommendations should include measures necessary to meet requirements and recommendations outlined in the manual. A copy of the recommendations of the district's technical advisor may be forwarded to the permit-issuing authority.
4. The permit-issuing authority of the local unit of government, after consultation with the governing board and after a thorough review of the plan for compliance with other resolutions or ordinances rules and regulations, should then issue or deny a permit. If a plan is not approved,
4-4

the modifications necessary to permit approval of the plan should be specified in writing. Time is of essence in erosion and sediment control plan processing. Act 599 states that permits shall be issued or denied as soon as practicable after the application is filed with the issuing authority-but in any event not later than 45 days of receipt of the plan and completed application.
Plan Revisions
An approved plan may be revised if inspections reveal that the erosion and sediment control plan is inadequate in accomplishing the objectives of the law. If so, modifications to correct the deficiencies must have the concurrence of the plan-reviewing authority.
Revision may also be required when the person responsible for carrying out the approved plan finds that, because of changed conditions or other reasons, the approved plan cannot be effectively carried out. Again, the plan reviewing authority must give concurrence on proposed plan changes.
Checklist of Plan Preparation and Review
A complete plan review checklist is presented on page 6-10. Some of the issues which the plan preparers and plan reviewers need to consider are:
1. Does the proposed plan contain information reflecting actual existing site conditions?
2. Will the roadways, buildings and other permanent features conform to the natural topography of the site?
3. Will the limitations of soils and steep slopes be overcome by sound engineering practices?
4. Will clearing be limited to only those areas of the site to be developed?
5. Will natural vegetation be retained and provisions made for protection of existing vegetation and for supplemental planting?
6. Will major land clearing and grading operations be scheduled during seasons of low potential sediment runoff?
7. Will the time of exposure of land clearing and grading be kept to a minimum?
8. Will permanent structures, temporary or permanent vegetation or mulch be scheduled for installation as quickly as possible after the land is disturbed?
GaSWCC (Amended - 1995)

9. Will all storm water management facilities, temporary or permanent, be designed to safely convey water to a stable outlet?
10. Will sediment basins, sediment barriers, and related devices be planned to filter or trap sediment on the site? Can these structures be easily maintained?
11. Will proposed vegetation be suitable for the intended use?
12. Do potential pollution hazards, including off-site sediment, noise and dust exist?
13. Are proposed permanent facilities subjected to flood or sediment damages?
14. Do subsurface conditions exist which could lead to pollution of ground water or aquifer recharge areas?
15. Is the construction schedule adequate?
16. Will erosion and sediment control measures be in place before extensive grading and clearing begins?
17. Have areas been designated for storage of salvaged topsoil?
18. Can all soil erosion and sediment control measures be adequately maintained?
INSPECTION AND ENFORCEMENT PROCESS
With regard to the inspection and enforcement process, it should be noted that it is not the purpose of this manual to support or promulgate specific courses of action by local authorities in these areas. Except as provided by Act 599, the local authorities are expected to exercise autonomy in determining the extent of any enforcement and inspection processes. The information provided here, as elsewhere in the manual, is only in keeping with the responsibility of a publication such as this to offer, for informational purposes, the alternatives available and in no way represents official opinion or recommendation.
These responsibilities begin after the issuance of a permit for a land-disturbing activity. A crucial element in any sediment and erosion control program is adequate field inspection for evaluating compliance to the approved erosion and sediment control plan.These inspections might be effectively incorporated in other existing local inspection programs.
Although Act 599 specifies that the actual responsibility for inspection is that of the governing authority, on-site
GaSWCC (Amended - 1995)

inspection may be assigned to a building inspector or another person employed by the local unit of government. The inspector, whether a soils engineer, civil engineer, soil conservationist, or technician, should have some knowledge in the field of soil and water conservation.
To assure that the enforcing agency and the permit applicant are in agreement about the control procedures to be followed, a pre-construction conference would be desirable. This conference should be held prior to beginning the land disturbing activity. All facets of the proposed work should be discussed at this meeting and anticipated problems reviewed.The need for installing temporary sediment control measures prior to actual clearing and grading operations should be emphasized. The individual responsible for carrying out the plan should also be informed of local inspection policies and schedules.
The institution of both scheduled and random inspections would be appropriate. The former would be a routine inspection related directly to construction operations and carried out on a rigid schedule. Random or impromptu site inspections would assure continuing compliance and the proper maintenance of erosion and sediment control measures.
The implementation of a record system would insure coordination of the inspection process with other departments and local agencies. The record system should contain a detailed filing system for all land-disturbing activities. This file should contain a record including the date of each inspection, the date land-disturbing activities commenced, and pertinent comments concerning compliance or noncompliance with the erosion and sediment control plan. In cases of noncompliance, the report should contain statements of the conservation measures needed for compliance and the recommended time in which such measures should be installed. Inspection reports should be immediately forwarded to the local governing authority.
In the event that inspections indicate a violation exists, some type of system for notifying the violator would probably be necessary. An effective system often utilized by authorities involves a written "Notice to Comply." Such a notice would describe the violation and give a detailed description of conservation measures necessary to assure compliance with the approved erosion and sediment control plan. If proper action is not taken within a reasonable time, the local governing authority could then prepare a letter of intent to utilize a performance bond, cash bond, escrow monies or other legal arrangement insuring installation of the approved measure.
The county engineer, building inspector, etc., would represent the issuing authority in handling complaints about missing or ineffective erosion control measures. When it is determined that ineffective erosion control measures are being followed but those measures comply with the approved erosion control plan, the city engineer, building in-
4-5

spector, etc., should notify the local Soil and Water Conservation District.
Checklist of Site Inspection
The process of inspecting construction operations requires knowledge of the basic principles and control measures in Chapter 2. A thorough understanding of the erosion and sediment control plan is absolutely essential. The following checklist is supplied to assist the inspector in fulfilling his responsibilities.
1. Are all erosion and sediment control measures in place, adequate and properly constructed?
2. Have clearing operations been confined within the limits as shown on the plan?
3. Is vegetation outside of the clearing area protected? Supplemented?
4. Is sediment being transported from the site onto public right-of-way by vehicular traffic?
5. Are erosion problems present in the vicinity of temporary or permanent storm water management facilities?
6. Are sediment basins, sediment barriers and related devices effective in retaining sediment on the site?
7. Is appropriate vegetation being established as needed on the specified area?
8. Is work progressing in accordance with the proposed schedule?
9. Is the contractor following the plan and construction sequence?
10. Have temporary stream channel crossings been installed and maintained?
11. Are embankment slopes and permanent structures installed in areas subject to flood or sediment damage?
12. Has topsoil been salvaged and stored in the area designated by the plans?
13. Do severe fire hazards exist which would result in brush or grass fires?
14. Are all erosion and sediment control measures properly maintained?
15. Is excessive sediment leaving the site for any reason?
16. Have all buffers adjacent to "state waters" been honored?
Enforcement, Penalties, and Incentives
4-6

For each proposed land-disturbing activity, a decision should be made on precautions insuring that conservation measures are installed. These precautions may include a cash bond, cash escrow, letter of credit, or any combination thereof. The purpose is to insure that the planned conservation measures are installed at the applicant's expense if he fails to do it within the specified time. If a cash incentive is used, it should be required prior to commencing the land disturbing activity.
In the event that the requirements of the erosion and sediment control plans are not being fulfilled, one alternative the local units of government may consider is withholding future permits such as additional grading, building, etc., involving the particular land-disturbing site.
Local authorities may consider assessing fees for erosion and sediment control plan processing. The cost of inspection services could be recouped, if desired, by levying permit fees.

INFORMATION, EDUCATION AND TRAINING PROCESS

One of the most important processes in any erosion and sediment control program is an effective information and education effort. A local program must have the acceptance and the support of those persons most affected... the developers, engineers, planners, and architects, as well as the general public. Without their support, effective sediment and erosion control will not take place. It is very important that the "conservation pays" ethic be adopted by these groups.

Each municipality and county must formulate plans for an information/education program. Consideration should be given to:

1. Informing the developer and others affected by the requirements of the local program and of the assistance which will be made available to them.

2. Training seminars, conferences and educational material for the developer, his consultants, contractors and other support personnel of the developers.

3. Training seminars for the local government personnel authorized to perform the functions of inspections and enforcement and administrative duties within the local erosion and sediment control program.

An initial training program for new employees, or personnel such as building inspectors who will have an added duty of inspection for erosion control, is mandatory. Annual refresher courses or training programs should be planned.

Assistance in planning and conducting local training pro-

grams may be obtained through the Soil and Water Con-

servation Districts.

GaSWCC (Amended - 1995)

CHAPTER 5

SOURCES OF ASSISTANCE AND RESOURCE INFORMATION

ASSISTANCE
Act 599 emphasizes local erosion and sedimentation control programs. Policies governing permit issuance, inspection and enforcement may therefore vary between each municipality or county. The individual contemplating a land-disturbing activity should contact the governing authority of the county or municipality having jurisdiction over the proposed land change. Contacts should be made during the earliest phases of planning to avoid costly changes or delays.
FOR ADMINISTRATIVE ASSISTANCE IN _________ _______________________________________COUNTY, CONTACT:___________________________________ _______________________________________________ _______________________________________________ _______________________________________________
Act 599 specifies that the plan review process will be accomplished by the local Soil and Water Conservation District or its delegated authority. To insure that the erosion and sediment control plan will conform to local requirements, the developers should contact a District Supervisor in the county in which the land-disturbing activity will take place early in the planning stage.
FOR TECHNICAL ASSISTANCE IN PREPARING AN EROSION AND SEDIMENT CONTROL PLAN IN _______________________________________COUNTY, CONTACT:

___________ District Supervisor or
___________ SWCD
___________
___________ Address

_____ District Conservationist
_____ NRCS Field Office
_____ Address
_____ Phone

GaSWCC (Amended - 2000)

RESOURCE INFORMATION
A wealth of resource data exists in various agencies which will assist in planning for land-disturbing activities and in the preparation of erosion and sediment control plans. If a specific address is not noted for the agency you need to contact, please refer to pages 5-3 to 5-10 to identify the agency's office nearest you.
Soils Information:
USDA Natural Resources Conservation Service
Georgia Soil and Water Conservation Commission
Local Soil and Water Conservation District
Topographic and Geologic Information:
Georgia Department of Natural Resources Environmental Protection Division Geologic Survey Branch Room 400 19 Martin Luther King, Jr. Drive Atlanta, GA 30334
Non-Point Source Pollution Control:
Georgia Department of Natural Resources Environmental Protection Division Water Protection Branch Non-Point Source Pollution Control Program 4220 International Parkway, Suite 101 Atlanta, GA 30354 (404) 675-6240
Fisheries Management:
Georgia Department of Natural Resources Wildlife Resources Division Fisheries Management Section
5-1

Stream Flow Information:
United States Department of the Interior Geological Survey Water Resources Division 1459 Peachtree Street, N.E. Atlanta, GA 30304
Flood Hazard, Wetlands and 404 Permit Information:
U. S. Army Corps of Engineers (COE)
Georgia Department of Natural Resources Environmental Protection Division Water Resources Branch Water Resources Management Program Floodplain Unit 7 Martin Luther King, Jr. Drive, Suite 440 Atlanta, GA 30334 (404) 656-6382
USDA Natural Resources Conservation Service
Agriculture Information:
Georgia Soil and Water Conservation Commission
USDA Natural Resources Conservation Service
Forestry Information:
Georgia Forestry Commission

5-2

GaSWCC (Amended - 2000)

GEORGIA SOIL AND WATER CONSERVATION COMMISSION
REGIONAL OFFICES

Dade

Catoosa

Fannin

Walker

Whitfield Murray Gilmer

Chattooga

Gordon

Pickens

REGION 1

Floyd

Bartow

Cherokee

Union

Towns

Rabun

Habersham

White Lumpkin

Stephens

Dawson Forsyth

Hall

Banks Franklin

REGION 2

Jackson

Madison

Hart Elbert

Polk Haralson

Paulding

Cobb

Gwinnett

REGION 3

Dekalb Douglas Fulton

Barrow Walton

Clarke Oglethorpe
Oconee

Wilkes

Lincoln

Rockdale

Carroll Heard
Troup

Clayton

Fayette Coweta

Henry

Spalding

Meriwether

Pike Lanier

Upson

Newton

Morgan

Greene Teliaferro

Columbia

Warren McDuffie

Butts Jasper

Putnam

Hancock

Glascock

REGION 4

Baldwin

Jefferson

Monroe

Jones

Washington

Richmond Burke

Harris

Talbot

Muscogee

Crawford

Bibb

Taylor

Peach

Wilkinson Twiggs

Johnson

Jenkins Screven Emanuel

Marion Chattahoochee

Macon

Houston Bleckley

Laurens

Treutlen

Bulloch Chandler

Effingham

Montgomery

Schley

Stewart Webster

Sumter

Dooly

Quitman

REGION 5 Crisp

Pulaski Wilcox

Dodge

Randolph Terrell

Lee

Turner

Ben Hill

Clay

Calhoun

Dougherty

Worth

Irwin Tift

Wheeler Telfair
Jeff Davis

Toombs

Evans

Tattnall
REGION 6

Appling

Long

Coffee

Bacon

Wayne

Bryan Liberty
McIntosh

Early

Baker

Miller

Mitchell

Colquitt

Berrien Atkinson Cook

Seminole

Decatur

Grady

Thomas

Brooks

Lanier

Clinch

Lowndes

Echols

Pierce

Ware

Brantley

Glynn

Charlton

Camden

Chatham

Region 1 700 East 2nd Avenue, Suite J Rome, Georgia 30161-3359 Phone: 706-295-6131
Region 3 1500 Klondike Road Suite A109 Conyers, Georgia 30094 Phone: 770-761-3020
Region 5 2700 Palmyra Road Albany, Georgia 31707-1845 Phone: 912-430-4480

Region 2 P.O. Box 8024 Athens, Georgia 30603 Phone: 706-542-9233
Region 4 3014 Heritage Road, Suite 1 Milledgeville, Georgia 31061 Phone: 912-445-5766
Region 6 117 Savannah Avenue Statesboro, Georgia 30458 Phone: 912-681-5241

Website

www.ganet.org/gswcc

GaSWCC (Amended - 2000)

5-3

GEORGIA SOIL AND WATER CONSERVATION DISTRICT ORGANIZATION

Soil and Water Conservation Commission Regions

Soil and Water Conservation Districts

R1 Region 1

1. Catoosa County

21. Piedmont

R2 Region 2

2. Coosa R.

22. Upper Ocmulgee R.

R3 Region 3

3. Cobb County

23. West County

R4 Region 4

4. Fulton County

24. Roosevelt

R5 Region 5

5. Clayton County

25. Towaliga

R6 Region 6

6. Lamar County

26. Brier Creek

7. Henry County

27. Central Georgia

8. Rockdale County

28. Ocmulgee R.

9. DeKalb County

29. Pine Mountain

10. Limestone Valley

30. Lower Chattahoochee R.

85 40'
35 00' +
Dade

TENNESSEE

NORTH CAROLINA

Catoosa
1

Fannin

Towns
11 Union

Rabun

11. Blue Ridge Mountain 31. Flint R.

12. Upper Chattahoochee R. 32. Middle South Georgia

13. Broad R.

33. Ohoopee R.

14. Oconee R.

34. Ogeechee R.

15. Gwinnett County

35. Coastal

Habersham

Walker

Murray Whitfield

Gilmer
10

White Lumpkin

39

16. Walton County 17. Lincoln County 18. Columbus County 19. McDuffie County

36. Altamaha 37. Satilla R. 38. Alapaha 39. Stephens County

Chattooga

Gordon
2 R1

Floyd

Bartow

Pickens Cherokee

12 40 Dawson
Forsyth Hall

Stephens

Banks Franklin

Hart

R2

13 Jackson Madison

Elbert

20. Warren County

40. Hall County

District Border Region Border

14 Polk
3 R39 158 16 17 Haralson

Cobb Paulding

Douglas

Fulton

Gwinnett Dekalb

Barrow

Clarke Oconee Oglethorpe

Walton

Wilkes

Lincoln

Rockdale

23 4 5 7 22 21 20 19 18 Carroll

Clayton

Fayette Coweta

Henry

Newton

Morgan

Greene Teliaferro

Columbia

Putnam

Warren McDuffie

Richmond

Heard

Spalding

R4 Jasper
Butts

Hancock

Glascock

Troup

24

Pike

6 25

Lanier

Monroe

Meriwether

Baldwin Jones

Washington

26 Jefferson

Burke

SOUTH CAROLINA ALABAMA

Upson

Harris

Talbot

29
Muscogee

ChattahoocheeMarion

Bibb Crawford

Wilkinson

Taylor

Twiggs

Peach
28 Houston

Bleckley

27
Laurens

Macon

Johnson

Jenkins Emanuel

Screven

Bulloch

33 Treutlen

Chandler

34

Effingham

Schley

Pulaski

N

Stewart Webster
30

R5
Sumter

Dooly Crisp

Wilcox

Dodge

Wheeler

Telfair

Evans Toombs Tattnall
R6

Bryan

Chatham

Quitman

Liberty

Randolph Terrell

Lee

Turner

Ben Hill

Jeff Davis
36

Appling

Long

35

Montgomery
ATLANTIC OCEAN

Clay

Calhoun

Dougherty

Early

Baker

Worth

Tift

32

Irwin Berrien

Coffee Atkinson

31 Miller
Seminole

Mitchell

Colquitt

Cook

Lanier
38

Clinch

Decatur

Grady

Thomas

Brooks

Lowndes

Echols

FLORIDA

Bacon

Wayne

Pierce

Ware

Brantley
37

McIntosh Glynn

Charlton

Camden

+30 40' 80 50'

0 20 40 60 80 100 MILES

5-4

GaSWCC (Amended - 2000)

GEORGIA DEPARTMENT OF NATURAL RESOURCES
ENVIRONMENTAL PROTECTION DIVISION

Dade

Catoosa

Fannin

Walker

Whitfield Murray Gilmer

Northwest Chattooga

Gordon

Pickens

Georgia Floyd

Bartow

Cherokee

Region Polk

Cobb

Paulding

Haralson

Douglas

Fulton

Union

Towns

Rabun

Habersham

White

Lumpkin

Stephens

Northeast Dawson

Banks Hall

Franklin

Hart

Forsyth Gwinnett

Georgia

Jackson

Madison

Elbert

Region Barrow

Clarke

Dekalb

Walton

Oglethorpe Oconee

Wilkes

Lincoln

Rockdale

Carroll

Clayton

Newton

Morgan

Greene

Teliaferro

Columbia McDuffie

Fayette

Henry

Warren

Heard

Coweta

Spalding

Butts

Jasper

Putnam

Hancock

Glascock

Richmond

Pike

Troup

Meriwether

Lanier

Monroe

Jones

Baldwin

Jefferson

Burke

Washington

Upson

BibbMiddle

Wilkinson

Harris

Talbot

Crawford

Georgia Twiggs

Johnson

Jenkins

Screven

Taylor

Emanuel

Muscogee Marion

Peach Houston

Region Bleckley

Laurens

Treutlen

Bulloch Chandler

Chattahoochee

Macon

Effingham

Montgomery

Stewart

Schley

Webster

Sumter

Quitman

Randolph

Terrell

Lee

Dooly

Pulaski

Dodge

Crisp

Wilcox

Turner

Ben Hill

Clay

Calhoun

Dougherty

Worth

Southwest Early

Baker

Georgia Miller

Mitchell

Colquitt

Irwin Tift
Berrien Cook

Wheeler

Toombs

Evans

Bryan

Tattnall

Telfair

Liberty

Jeff Davis

Appling

Long

Coastal

Coffee

Bacon

Wayne

McIntosh

Georgia Pierce

Atkinson

Brantley
RegionGlynn
Ware

Seminole

Region

Decatur

Grady Thomas

Brooks

Lanier Lowndes

Clinch

Charlton

Camden

Echols

Chatham

Northwest Georgia Region Tradeport Office Park, Suite 114 4244 International Parkway Atlanta, Georgia 30354 Phone: 404-362-2671
Middle Georgia Region P.O. Box 233 Macon, Georgia 31211 Phone: 912-751-6612
Southwest Georgia Region 2024 Newton Road Albany, Georgia 31708 Phone: 912-430-4144

Northeast Georgia Region 745 Gaines School Road Athens, Georgia 30605 Phone: 706-369-6398
Coastal Georgia Region One Conservation Way Brunswick, Georgia 31523 Phone: 912-264-7284

GaSWCC (Amended - 2000)

Website www.dnr.state.ga.us/epd

5-5

5-6

GEORGIA DEPARTMENT OF
NATURAL RESOURCES WILDLIFE RESOURCES DIVISION FISHERIES MANAGEMENT SECTION

Dade

Catoosa

Fannin

Walker

Whitfield Murray

Gilmer

Chattooga

Gordon

Pickens

Floyd

Bartow

Cherokee

Region 1

Union

Towns

Rabun

Habersham White

Lumpkin

Stephens

Region Dawson 2

Banks Hall

Franklin

Forsyth

Jackson

Madison

Hart Elbert

Polk Haralson
Carroll

Paulding

Cobb

Gwinnett

Barrow

Douglas

Dekalb

Walton

Rockdale

Fulton Clayton

Newton

Clarke

Oglethorpe Oconee

Wilkes
Region 3

Morgan

Greene Teliaferro

Lincoln Columbia

Fayette

Henry

Coweta

Heard

Region 4 Spalding

Butts

Jasper

Putnam

Hancock

Warren McDuffie Glascock

Richmond

Troup

Meriwether

Pike Lanier Monroe

Jones

Baldwin

Washington

Jefferson

Burke

Upson

Harris

Talbot

Bibb Crawford

Wilkinson Twiggs

Johnson

Jenkins

Muscogee

Taylor

Peach

Emanuel

Screven

Marion Chattahoochee

Macon

Houston Bleckley

Laurens

Treutlen

Chandler

Bulloch

Effingham

Montgomery

Stewart

Webster

Schley Sumter

Region 5 Quitman

Randolph

Terrell

Lee

Clay Calhoun

Dougherty

Early Miller

Baker Mitchell

Dooly

Pulaski

Dodge

Wheeler

Toombs

Evans

Bryan

Crisp

Wilcox

Telfair

Tattnall

Chatham

Turner

Ben Hill Irwin

Jeff Davis

Appling

Liberty Long
Region 7

Worth Colquitt

Coffee

Bacon

Tift Region 6

Berrien

Atkinson

Cook

Ware

Wayne Pierce
Brantley

McIntosh Glynn

Seminole

Decatur

Grady

Thomas

Lanier

Brooks

Lowndes

Clinch

Charlton

Camden

Echols

Region 1 - Northwestern P.O. Box 519 Calhoun, Georgia 30703 Phone: 706-629-1259
Region 3 - East Central 2123 U.S. Highway 278, S.E. Social Circle, Georgia 30279 Phone: 770-918-6418
Region 5 - Southwestern 2024 Newton Road Albany, Georgia 31701 Phone: 912-430-4256
Region 7 - Coastal 22814 Highway 144 Richmond Hill, Georgia 31324 Phone: 912-727-2112

Region 2 - Northeastern 2150 Dawsonville Highway Gainesville, Georgia 30501 Phone: 770-535-5498
Region 4 - West Central Route 3, Box 75 Fort Valley, Georgia 31030 Phone: 912-825-6151
Region 6 - South Central P.O. Box 2089 Waycross, Georgia 31502 Phone: 912-285-6094

Website www.state.ga.us/dnr/wild

GaSWCC (Amended - 2000)

GEORGIA DEPARTMENT OF TRANSPORTATION DISTRICT OFFICES

Dade

Catoosa Whitfield Murray

Fannin

Union

Towns

Rabun

Walker

Gilmer

Habersham

White

District 6 Chattooga

Gordon

Pickens

Lumpkin

Stephens

Floyd

Bartow

Cherokee

District 1 Dawson

Hall

Banks Franklin

Forsyth

Hart

Jackson

Madison

Elbert

Polk Haralson
Carroll

Paulding

Cobb

Gwinnett

Barrow

District 7 Douglas

Dekalb

Fulton Clayton

Rockdale

Walton Newton

Clarke Oconee
Morgan

Oglethorpe

Wilkes

Lincoln

Greene

Teliaferro

Columbia McDuffie

Heard

Coweta

Fayette

Henry

Spalding

Butts

Jasper

Putnam

Hancock

Warren Glascock

Richmond

Troup

Meriwether

Pike Lanier Monroe
Upson

Jones

District 2

Baldwin

Jefferson

Burke

Washington

Bibb

District 3 Harris

Talbot

Crawford

Wilkinson Twiggs

Johnson

Jenkins

Muscogee

Taylor

Peach

Emanuel

Screven

Marion Chattahoochee

Macon

Houston Bleckley

Laurens

Treutlen

Bulloch Chandler

Effingham

Montgomery

Stewart

Schley

Webster

Sumter

Quitman

Randolph

Terrell

Lee

Dooly

Pulaski

Dodge

Wheeler

Crisp

Wilcox

Telfair

Turner

Ben Hill

Jeff Davis

Toombs

Evans

Tattnall

Bryan

Appling

Long

Liberty

Clay

Calhoun

Dougherty

Worth

Early

DBakierstrict 4

Miller

Mitchell

Colquitt

Irwin Tift
Berrien Cook

Coffee Atkinson

District 5 Bacon

Wayne

McIntosh

Pierce

Ware

Brantley

Glynn

Seminole Decatur

Grady

Thomas

Lanier

Brooks

Lowndes

Clinch

Charlton

Camden

Echols

Chatham

District 1 - Gainesville, GA P.O. Box 1057 Gainesville, Georgia 30503 Phone: 770-532-5526
District 3 - Thomaston, GA 715 Andrews Drive Thomaston, Georgia 30286 Phone: 706-647-1000
District 5 - Jesup, GA Pine Street Extension P.O. Box 608 Jesup, Georgia 31545 Phone: 912-427-5711

District 2 - Tennille, GA 801 Fourth Street P.O. Box 8 Tennille, Georgia 31089 Phone: 912-552-4600
District 4 - Tifton, GA 710 West Second Street P.O. Box 7510 Tifton, Georgia 31793-7510 Phone: 912-386-3280
District 6 - Cartersville, GA 500 Joe Frank Harris Pkwy, S.E. P.O. Box 10 Cartersville, Georgia 30120 Phone: 770-387-3602

District 7 - Chamblee, GA 5025 New Peachtree Road, N.E. Chamblee, Georgia 30341 Phone: 770-986-1001

GaSWCC (Amended - 2000)

Website www.dot.state.ga.us

5-7

GEORGIA FORESTRY COMMISSION WATER QUALITY DISTRICTS

Dade

Catoosa Whitfield Murray

Fannin

Union

Towns

Rabun

Habersham

Walker

Gilmer

White

Lumpkin

Stephens

Chattooga

Gordon

Pickens

District 1

District 2
Dawson Banks Franklin

Hall

Hart

Floyd

Bartow

Cherokee

Forsyth

Jackson

Madison

Elbert

Polk Haralson
Carroll

Paulding

Cobb

Douglas

Gwinnett

Barrow

Clarke

Oconee Oglethorpe

District 3 Dekalb

Walton

Wilkes

Rockdale

Fulton Clayton

Newton

Morgan

Greene Teliaferro

Lincoln McDuffie Columbia

Fayette

Henry

Coweta

Heard

Spalding

Butts

District 4

Jasper

Putnam

Hancock

Warren Richmond
Glascock
District 6

Troup

Meriwether

Pike Lanier Monroe
Upson

Baldwin Jones
District 5Washington

Jefferson

Burke

Harris

Talbot

Crawford

Bibb

Wilkinson Twiggs

Johnson

Jenkins

Screven

Muscogee

Taylor

Peach

Emanuel

Marion Chattahoochee

Macon

Schley

Stewart

Webster

Sumter

District 7

Montgomery

Houston Bleckley

Laurens

Treutlen

District 11

Dooly

Pulaski

Dodge

Wheeler

Toombs

Crisp

Wilcox

Telfair

Quitman

Randolph

Terrell

Lee

Turner

Ben Hill

Jeff Davis

Appling

Clay

Calhoun

Dougherty

DistrictIrw8in
Worth Tift

Coffee

Bacon

Chandler Bulloch Effingham
District 10 Evans Bryan

Tattnall

Chatham

Liberty Long

Wayne

McIntosh

Early Miller

Baker Mitchell

Colquitt

Berrien Cook

Pierce
Atkinson District 12 Brantley
Ware

Seminole District 9

Lanier

Clinch

Decatur

Grady

Thomas

Brooks

Charlton

Lowndes

Echols

Glynn Camden

District 1 - Rome, GA Phone: 706-295-6021
District 3 - Athens, GA Phone: 706-542-6880
District 5 - Milledgeville, GA Phone: 912-445-5164
District 7 - Americus, GA Phone: 912-931-2436
District 9 - Camilla, GA Phone: 912-336-5341
District 11 - McRae, GA Phone: 912-868-5649

District 2 - Gainesville, GA Phone: 770-531-6043
District 4 - Newnan, GA Phone: 770-254-7218
District 6 - Washington, GA Phone: 706-678-2015
District 8 - Tifton, GA Phone: 912-386-3617
District 10 - Statesboro, GA Phone: 912-681-5347
District 12 - Waycross, GA Phone: 912-287-4917

Website www.gfc.state.ga.us

5-8

GaSWCC (Amended - 2000)

UNITED STATES ARMY CORPS OF ENGINEERS
GEORGIA AREA SECTIONS

Dade

Catoosa

Fannin

Walker

Whitfield Murray Gilmer

Chattooga

Gordon

Pickens

Union

Towns

Rabun

Lumpkin

White

Stephens

Habersham

Dawson

Banks Franklin Hall

Floyd

Bartow

Cherokee

Forsyth

North

Area

Section Jackson

Madison

Hart Elbert

Polk Haralson
Carroll

Paulding

Cobb

Douglas

Gwinnett Dekalb

Barrow Walton

Clarke Oconee Oglethorpe

Wilkes

Rockdale

Fulton Clayton

Newton

Morgan

Greene Teliaferro

Lincoln McDuffie Columbia

Heard

Coweta

Fayette

Henry

Spalding

Butts

Jasper

Putnam

Hancock

Warren Glascock

Richmond

Troup

Meriwether

Pike Lanier Monroe
Upson

Jones

Baldwin

Washington

Jefferson

Burke

Harris

Talbot

Muscogee

Taylor

Crawford

Bibb

Peach

Wilkinson Twiggs

Johnson

Jenkins

Screven

Emanuel

Marion Chattahoochee

Macon

Houston Bleckley

Laurens

Treutlen

Chandler Bulloch

Effingham

Montgomery

Stewart

Schley

Dooly

Pulaski

Dodge

Wheeler

Webster

Sumter

Crisp

Wilcox

Telfair

Quitman

Central Area Section Randolph

Terrell

Lee

Turner

Ben Hill

Jeff Davis

Toombs Appling

Clay

Calhoun

Dougherty

Worth

Irwin Tift

Coffee

Bacon

Evans Tattnall

Bryan

Chatham

Coastal Liberty Long
Area

Section Wayne

McIntosh

Early Miller

Baker Mitchell

Colquitt

Berrien Cook

Atkinson

Pierce

Ware

Brantley

Glynn

Seminole

Decatur

Grady

Thomas

Brooks

Lanier Lowndes

Clinch

Charlton

Camden

Echols

Central and Coastal Area Sections U.S. Army Corps of Engineers Attention: Regulatory Branch P.O. Box 889 Savannah, Georgia 31402-0889 Phone: 912-652-5347 1-800-448-2402
North Area Sections U.S. Army Corps of Engineers Attention: Regulatory Branch
3485 North Desert Drive Building 2, Suite 102
Atlanta, Georgia 30344 Phone: 404-763-7933

GaSWCC (Amended - 2000)

Website www.usace.army.mil

5-9

5-10

GEORGIA NATURAL RESOURCES CONSERVATION SERVICE
AREA OFFICES

Dade

Catoosa

Fannin

Walker

Whitfield Murray Gilmer

Chattooga

Gordon

Pickens

Area 1 Floyd

Bartow

Cherokee

Union

Towns

Rabun

Habersham

Lumpkin

White

Stephens

Dawson Forsyth

Banks Franklin Hall

Jackson

Madison

Hart Elbert

Polk Haralson
Carroll

Paulding

Cobb

Douglas

Gwinnett Dekalb

Barrow

Clarke

Oconee Oglethorpe
Area 2 Walton

Wilkes

Lincoln

Rockdale

Fulton Clayton

Newton

Morgan

Greene Teliaferro

McDuffie Columbia

Heard

Coweta

Fayette

Henry

Spalding

Butts

Jasper

Putnam

Hancock

Warren Glascock

Richmond

Troup

Meriwether

Pike Lanier Monroe
Upson

Jones

Baldwin

Washington

Jefferson

Burke

Harris

Talbot

Muscogee

Taylor

Crawford

Bibb

Peach

Wilkinson Twiggs

Johnson

Jenkins

Screven

Emanuel

Marion Chattahoochee

Macon

Houston

Bleckley

Laurens

Treutlen

Chandler Bulloch

Effingham

Montgomery

Stewart

Schley

Webster

Sumter

Quitman

Randolph

Terrell

Lee

Dooly

Pulaski

Dodge

Wheeler

Crisp

Wilcox

Telfair

Turner

Ben Hill

Jeff Davis

Toombs

Evans

Tattnall

Bryan

Liberty

Area 4 Appling

Long

Chatham

Clay

Calhoun

Area 3 Dougherty

Worth

Irwin Tift

Coffee

Early Miller

Baker Mitchell

Colquitt

Berrien Cook

Atkinson

Seminole Decatur

Grady

Thomas

Brooks

Lanier

Clinch

Lowndes

Echols

Bacon

Wayne

Pierce

Ware

Brantley

McIntosh Glynn

Charlton

Camden

Area 1 Federal Building, Room G-27 201 West Solomon Street Griffin, Georgia 30224-3037 Phone: 770-227-1026
Area 2 Federal Building 355 East Hancock Ave. Athens, GA 30601 Phone: 706-546-2272
Area 3 Plant Materials Center 295 Morris Drive Americus, GA 31709-9999 Phone: 912-924-7003
Area 4 Federal Building, Room 214 601 Tebeau Street Waycross, Georgia 31502-4701 Phone: 912-283-5598

Website www.nrcs.usda.gov

GaSWCC (Amended - 2000)

CHAPTER 6
BMP STANDARDS AND SPECIFICATIONS FOR GENERAL LANDDISTURBING ACTIVITIES
This chapter contains Standards and Specifications for planning, design and installation of erosion and sediment control measures. They are intended to provide minimum criteria for use at the local level. The many variations in climate, soils, topography, physical features and planned land use may require modifications at the local level. Local officials will assure that standards and specifications are implemented in harmony with existing ordinances, rules and regulations.
Variations of these standards have been in use since late 1930's, when Soil and Water Conservation Districts were first established. Continuing progress through experience and research will require periodic updating. The construction specifications contained herein are not intended to be complete. Detailed construction specifications should be prepared for each land-disturbing activity.
Information has been included on geotextiles based on the American Association of State Highway Transportation Officials (AASHTO). Information on Forestry Best Management Practices can be found in the Georgia Forestry Commission's publication entitled Georgia's Best Management Practices for Forestry.
Erosion control is of primary importance during landdisturbing activities, but sediment storage must be available on the site. Temporary sediment basins and retrofitted detention ponds most commonly achieve the required 67 cubic yards per acre of disturbed area of storage. Some situations may call for the use of practices other than those mentioned above. Appropriate sediment storage must be available on the site PRIOR to any land-disturbing activities. It is imperative that creative engineering practices are used to ensure that erosion and sediment control BMP's are appropriate for the situation and activity. Linear projects pose special treatment concerning erosion and sediment control. Guidelines for dealing with linear projects has been included.

Shall or Will, Should, and May are used in these specifications with the following definitions: Shall or Will - A mandatory condition. When certain requirements are described with the "shall" or "will" stipulations, it is mandatory that the requirements be met. Should - An advisory condition. Considered to be recommended but not mandatory. May - A permissive condition. No requirement is intended.
Section I contains standards providing general instructions for the preparation of erosion and sediment control plans for land-disturbing activities.
Section II contains standards and specifications for vegetative type measures for general land-disturbing activities.
Section III contains standards for structural practices and provides instructions for the preparation of erosion and sediment control plans for land-disturbing activities.
Section IV contains tables for design of vegetated diversion, waterway or stormwater conveyance practices.

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6-2

GaSWCC (Amended - 2000)

Waters of the United States and Erosion and Sediment Control
Wetlands are defined as areas that are inundated by surface or ground water for a long enough period of time that the area supports the growth of vegetation that can perpetuate in saturated soil. Wetlands are a valuable resource, and it is imperative that these areas are protected from damage caused by adjacent erosion and subsequent sedimentation. While state law does not necessarily require buffers adjacent to wetlands, these areas are still considered valuable, and all efforts must be made to protect these areas during land disturbing activities. Obviously, the best and most effective method for protecting wetlands is maintaining a buffer between and land-disturbing activity and the wetland. If this is not possible, standard erosion and sediment control devices can be utilized to protect these areas. As always, it is imperative that these devices be designed, installed, and properly maintained.
The Georgia Erosion and Sediment Control (E&SC) Act requires that land-disturbing activities in Georgia are protected from erosion and subsequent sedimentation up to and including a 25-year storm. Few realize that activities that impact Waters of the United States can mean stricter Federal requirements for erosion and sediment control. Waters of the United States are navigable waters as well as adjacent wetlands and tributaries to navigable waters. Discharge of dredged of fill material into Waters of the United States is regulated

by the United States Army Corps of Engineers under Section 404 of the Clean Water Act (33 U.S.C. 1344).
While State Law requires E&SC protection for a 25year storm, Federal Law requires that adequate erosion and sediment control must be implemented during land-disturbing activities where a section 404 permit (usually known as a wetland permit) is required. Few realize that minor activities of filling and dredging, while not requiring U.S. Army Corps of Engineers notification, still must meet the Federal requirement of "adequate erosion and sediment control" as if a permit had been issued. According to Federal Law, "adequate equates to "no failures tolerated." In short, when filling or dredging activity impacts any Waters of the United States, adequate erosion control must occur at the site. Therefore, during land-disturbing activities regulated by the state, erosion and sediment control regulations fall under stricter Federal guidelines as well as the standard State guidelines if Waters of the United States are impacted.
To get more information concerning discharge of dredged or fill material into Waters of the United States, permitting for these activities, and stipulations for permitting please contact the United States Army Corps of Engineers, Savannah District, Regulatory Branch, at 1800-652-5065.

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GaSWCC (Amended - 2000)

STANDARDS AND SPECIFICATIONS

Page

SECTION I: LAND-DISTURBING ACTIVITY PLAN

LAND-DISTURBING PLAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-9

SECTION II:
Bf Cs

VEGETATIVE MEASURES BUFFER ZONE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-19 COASTAL DUNE STABILIZATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-29

Ds1

DISTURBED AREA STABILIZATION (WITH MULCHING ONLY) . . . . . . . . . . . . . . . . . . . . . . . 6-33

Ds2 Ds3

DISTURBED AREA STABILIZATION (WITH TEMPORARY SEEDING) . . . . . . . . . . . . . . . . . . 6-35 DISTURBED AREA STABILIZATION (WITH PERMANENT VEGETATION) . . . . . . . . . . . . . . . 6-41

Ds4 Du Mb

DISTURBED AREA STABILIZATION (WITH SODDING) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-57 DUST CONTROL ON DISTURBED AREAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-61 EROSION CONTROL MATTING AND BLANKETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-63

Pm

POLYACRYLAMIDE (PAM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-67

Sb

STREAMBANK STABILIZATION (USING PERMANENT VEGETATION) . . . . . . . . . . . . . . . . . 6-69

Tb

TACKIFIERS AND BINDERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-73

SECTION III: STRUCTURAL PRACTICES

Cd

CHECKDAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-77

Ch

CHANNEL STABILIZATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-81

Co

CONSTRUCTION EXIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-85

Cr

CONSTRUCTION ROAD STABILIZATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-87

Dc

STREAM DIVERSION CHANNEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-89

Di

DIVERSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-93

Dn1 Dn2
Fr Ga Gr

TEMPORARY DOWNDRAIN STRUCTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-97 PERMANENT DOWNDRAIN STRUCTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-101 FILTER RING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-103 GABION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-105 GRADE STABILIZATION STRUCTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-107

Lv

LEVEL SPREADER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-115

GaSWCC (Amended - 2000)

6-5

Rd

ROCK FILTER DAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-117

Re

RETAINING WALL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-121

Rt

RETROFIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-123

Sd1

SEDIMENT BARRIER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-127

Sd2

INLET SEDIMENT TRAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-139

Sd3

TEMPORARY SEDIMENT BASIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-147

Sr

TEMPORARY STREAM CROSSING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-173

St

STORM DRAIN OUTLET PROTECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-179

Su

SURFACE ROUGHENING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-185

Tp

TOPSOILING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-189

Wt

VEGETATED WATERWAY OR STORMWATER CONVEYANCE CHANNEL . . . . . . . . . . . . . . . 6-191

SECTION IV: TABLES FOR DESIGN OF VEGETATED DIVERSION, WATERWAY OR STORMWATER CONVEYENCE PRACTICES

TABLE 6-28.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-205

TABLE 6-28.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-219

TABLE 6-28.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-233

TABLE 6-28.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-235

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GaSWCC (Amended - 2000)

SECTION I: LAND-DISTURBING ACTIVITY PLAN

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GaSWCC (Amended - 2000)

LAND-DISTURBING ACTIVITY PLAN
DEFINITION
A plan for the control of soil erosion and sedimentation resulting from a land-disturbing activity.
PURPOSE
The purpose of this standard is to provide instructions for the preparation of detailed plans for a proposed land-disturbing activity in order to accomplish one or more of the following:
1. provide suitable sites for buildings, roadways, facilities and other land uses.
2. improve surface drainage. 3. control soil erosion and sediment deposition.
CONDITION
This standard is applicable where land-disturbing activities are undertaken for any of the purposes set forth above.
PLANNING CRITERIA
This land-disturbing activity plan shall be based upon adequate surveys, resource data and investigations. Erosion and sediment control measures shall be designed in accordance with the applicable standard applied herein. Practical combinations of the following principles shall be utilized, as a minimum, in planning for any land-disturbing activity.
1. Fit the Activity to the Topography and Soils.
Detailed planning should be employed to assure that roadways, buildings and other permanent features of the activity conform to the natural characteristics of the site. Large graded areas should be located on the most level portion of this site. Areas subject to flooding should be avoided. Areas of steep slopes, erodible soils and soils with severe limitations for the intended uses should not be utilized without overcoming the limitations through sound engineering practices. Erosion control, development and maintenance costs can be minimized if a site is selected for a specific activity.
2. The Disturbed Area and the Duration of Exposure to Erosion Elements Should Be Minimized.
Clearing of natural vegetation should be limited to only those areas of the site to be developed at a given time. Natural vegetation should be retained, protected and supplemented with construction scheduling employed to limit the duration of soil exposure. Major land
GaSWCC (Amended - 2000)

clearing and grading operations should be scheduled during seasons of low potential runoff.
3. Stabilize Disturbed Areas Immediately.
Permanent structures, temporary or permanent vegetation, and mulch, or a combination of these measures, should be employed as quickly as possible after the land is disturbed. Temporary vegetation and mulches can be most effective on areas where it is not practical to establish permanent vegetation. These temporary measures should be employed immediately after rough grading is completed if a delay is anticipated in obtaining finished grade. The finished slope of a cut or fill should be stable and ease of maintenance considered in the design. Stabilize all roadways, parking areas, and paved areas with the gravel subbase, temporary vegetation or mulch. Mulch, temporary vegetation, or permanent vegetation shall be completed on all exposed areas within 14 days after disturbance. Mulch and/or temporary grassing may be used up to six months; permanent vegetation shall be planted if the area is to be left undisturbed for greater than six months.
4. Retain or Accommodate Runoff.
Runoff from the development should be safely conveyed to a stable outlet using storm drains, diversions, stable waterways or similar conservation measures. Consideration should also be given to the installation of storm water retention structures to prevent flooding and damage to downstream facilities resulting from increased runoff from the site. Temporary or permanent facilities for conveyance of storm water should be designed to withstand the velocities of projected peak discharges. These facilities should be operational as soon as possible after the start of construction, and if possible before the disturbance of the surrounding areas.
5. Retain Sediment.
Sediment basins, sediment barriers and related structures should be installed to filter or trap sediment on the site to be disturbed. The most effective method of controlling sediment, however, is to control erosion at its source. Sediment retention structures should be planned to retain sediment when erosion control methods are not practical, or insufficient, or in the process of being installed, or have failed due to some unforeseen factor. If possible, the structures should be installed before the disturbance of surrounding areas.
6. Do Not Encroach Upon Watercourses.
Permanent buildings should not be subjected to flooding, sediment damages or erosion hazards. Earth fills should not be constructed in flood-prone areas so as to adversely obstruct water flows or increase downstream velocity of water flows. When necessary to span a flood prone area or watercourse, bridge or culvert openings
6-9

should be sized to permit passage of peak discharges without causing undue restrictions in water flows or without creating excessive downstream velocities. Uses of flood prone areas should be limited to activities which would not suffer excessive damages from flooding, scour, and sediment damages. Temporary bridges or culverts should be employed when construction equipment is required to cross natural or constructed channels.
PLAN REQUIREMENTS
The land-disturbing activity plan should contain a narrative description of the project, maps, drawings, computations and supportive data in accordance with the following guidelines.
Narrative Description
A brief description of the overall project containing:
1. Location, nature, size, and zoning classification of the overall project.
2. Location, nature and size of each phase of development.
3. Size, type of structural units, paved areas and green-belt area.
4. Starting dates of initial land-disturbing activities and date expected final stabilization will be completed.
5. Existing and proposed erosion and sediment control problems for the proposed site.
6. Purpose, nature and extent of proposed sediment control program.
7. Proposed storm water management program for the development and the effect of the development on downstream facilities.
8. Major topographic features, streams, existing soil types and vegetation located on the project site.
9. Maintenance programs for the sediment control facilities including inspection frequencies, vegetative programs, repair procedures, frequency of removal and disposition of solid waste and disposition of temporary sediment structural measures.
Maps
Detailed maps, drawings and sketches showing:
1. A location sketch of the project relative to roadways, municipalities, major streams and other identifiable landmarks.
6-10

2. A boundary line survey or detailed boundary sketch of the proposed project.
3. Contours, existing and proposed, for that portion of the activity being developed.
4. Soils boundaries including name, texture, slope, depth, drainage and structure.
5. Streams and drainage areas, lakes or ponds, flood prone areas, vegetation and existing structures.
6. The proposed alteration of the area including limits of clearing and grading, roads, buildings and structures.
7. Location and extent of temporary and permanent erosion and sediment control measures including both vegetative and structural practices.
8. Location and extent of storm water management facilities.
9. Other significant features including legend, map scales, north arrow, title blocks, seals and signatures.
Activity Schedules
For each phase or stage of land-disturbing activity, an activity schedule will be included. The activity schedule will show the anticipated starting and completion date for all land development activities including:
1. Timber salvage operations
2. Installation of construction exit, sediment barriers, and other perimeter controls
3. Clearing and grubbing of areas necessary for the installation of sediment retention basins and related structures
4. Installation of sediment retention basins and related structures
5. Clearing and grubbing of remaining areas
6. Rough grading
7. Installation of stormwater management system
8. Permanent stabilization of areas at final grade and temporary stabilization of remaining areas
9. Installation of curb and gutter
10. Installation of gravel subbase for roads and parking areas (construction road stabilization)
11. Building construction
GaSWCC (Amended - 2000)

12. Final grading
13. Permanent stabilization/landscaping
14. Removal of erosion and sediment control measures.
Supportive Data
Supportive data shall include reference to the applicable standards and specifications, calculations, charts, graphs, maps and any other data used in the design and layout of the measures installed.
CONSTRUCTION SPECIFICATIONS
All timber having a marketable value shall be salvaged. Timber logs, brush, rubbish, and vegetable matter which will interfere with the grading operations or affect the planned stability of fill areas shall be removed and disposed of according to the plan and in accordance with all local and state laws.
Topsoil is to be stripped and stockpiled in amounts necessary or available on site to complete final grading of all exposed areas.
Fill material is to be free of brush, rubbish, rocks, logs, and stumps in amounts that are detrimental to constructing stable fills.
Cut slopes which are to be top soiled will be scarified to a minimum depth of 3 inches prior to placement of topsoil.
Compaction of fills will be as required to reduce slipping, erosions or excess saturation.
Frozen mixtures of soft, mucky or easily compressible materials are not to be incorporated in fills intended to support buildings, parking lots, road, structures, sewers, or conduits.
Maximum thickness of layers to be compacted by sheeps foot rollers are not to exceed 9 inches.
All disturbed areas shall be left with a neat and finished appearance and stabilized with the appropriate permanent protective cover.
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EROSION AND SEDIMENT CONTROL PLAN REVIEW CHECKLIST FOR LINEAR PROJECTS
Project Name _______________________________ Address ______________________________________
City/County _________________________________ Date on Plans __________________________________
Site Plan: 1) Show graphic scale and north arrow. 2) Provide vicinity map showing site's relation to surrounding area. 3) Provide both existing and planned contours in accordance with the following:
Existing contours: USGS 1" : 2000' topographical sheets Proposed contours: 1" : 400' centerline profile 4) Delineate on-site drainage and off-site watersheds using USGS 1" : 2000' topographical sheets. 5) Delineate all state waters located on or within 200 feet of the project site - refer to 1" : 2000' USGS topographical sheets, published soil surveys, GIS information, etc. 6) Show location of erosion and sediment practices using uniform coding symbols from the Manual for Erosion and Sediment Control in Georgia, Chapter 6, with legend. 7) Delineate 25-foot undisturbed buffers of state waters and 50-foot management zones along designated trout streams. Clearly note areas of impact. 8) Delineate all wetlands and provide regulatory documentation permitting any proposed impacts. 9) Include soil series and their delineation. 10) Describe adjacent areas - neighboring areas such as streams, lakes, residential areas, etc., which might be affected.
Narrative Notes and Other Information: (Notes or narrative should be located on the site plan under general notes or under erosion and sediment control notes.) 1) Provide description of existing land use at project site and description of proposed project. Include land lot
and district numbers for site location. 2) Provide name, address and phone number of utility/contractor. 3) Provide name and phone number of 24-hour local contact that is responsible for erosion and sediment
controls. 4) Show signature and seal of qualified plan preparer. 5) Note total and disturbed acreage of the project or phase under construction. 6) Provide detailed construction activity schedule - show anticipated starting and completion dates for project
events, include vegetation and mulching timeline. 7) Clearly note the statement in bold letters: "The escape of sediment from the site shall be prevented by
the installation of erosion and sediment control measures and practices prior to, or concurrent with, land-disturbing activities." 8) Provide 67 cubic yards per acre sediment storage. Include specific design information and calculations for structural measures on site. 9) Show storm-drain pipe and weir velocities and provide appropriate outlet protection to accommodate discharges without erosion. 10) Provide vegetative plan, noting all temporary and permanent vegetative practices. Include species, planting dates and seeding, fertilizer, lime, and mulching rates. Vegetative plan shall be site specific for appropriate time of year that seeding will take place and for the appropriate geographic region of Georgia. 11) Provide detailed drawings for all structural practices. Specifications must, at a minimum, meet guidelines set forth in the Manual for Erosion and Sediment Control in Georgia. 12) Clearly note maintenance statement - "Erosion control measures will be maintained at all times. If full implementation of the approved plan does not provide for effective erosion control, additional erosion and sediment control measures shall be implemented to control or treat the sediment source."

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GaSWCC (Amended - 2000)

EROSION AND SEDIMENT CONTROL PLAN REVIEW CHECKLIST
Project Name _______________________________ Address ______________________________________

City/County _________________________________ Date on Plans __________________________________

Site Plan: 1) Show graphic scale and north arrow. 2) Provide vicinity map showing site's relation to surrounding area, including designation of specific phase, if
necessary. 3) Provide both existing and planned contours with contour lines drawn at an interval in accordance with the
following:

Map Scale

Ground Slope

Contour interval, ft.

1 inch= 100 ft. or larger scale

Flat 0-2% Rolling 2-8% Steep 8% +

0.5 or 1 1 or 2 2, 5 or 10

4) Delineate contributing drainage areas both on and off site. Include hydrology study and maps of drainage basins for both the pre- and post-developed conditions.
5) Delineate all state waters located on or within 200 feet of the project site. 6) Show location of erosion and sediment practices using uniform coding symbols from the Manual for
Erosion and Sediment Control in Georgia, Chapter 6, with legend. 7) Delineate 25-foot undisturbed buffers of state waters and 50-foot management zones along designated
trout streams. Clearly note areas of impact. 8) Delineate all wetlands and provide regulatory documentation permitting any proposed impacts. 9) Include soil series and their delineation. 10) Describe adjacent areas - neighboring areas such as streams, lakes, residential areas, etc., which might
be affected.
Narrative Notes and Other Information: (Notes or narrative should be located on the site plan under general notes or under erosion and sediment control notes.) 1) Provide statement from local tax official that all ad valorem taxes owed and due have been paid. 2) Provide description of existing land use at project site and description of proposed project. Include land lot
and district numbers for site location. 3) Provide name, address and phone number of developer/owner. 4) Provide name and phone number of 24-hour local contact that is responsible for erosion and sediment controls. 5) Show signature and seal of qualified plan preparer. 6) Note total and disturbed acreage of the project or phase under construction. 7) Provide detailed construction activity schedule - show anticipated starting and completion dates for project
events, include vegetation and mulching timeline. 8) Clearly note the statement in bold letters: "The escape of sediment from the site shall be prevented by
the installation of erosion and sediment control measures and practices prior to, or concurrent with, land-disturbing activities." 9) Provide 67 cubic yards per acre sediment storage. Include specific design information and calculations for all structural measures on site, such as temporary sediment basins, retrofitted detention ponds, and channels. 10) Show storm-drain pipe and weir velocities and provide appropriate outlet protection to accommodate discharges without erosion. 11) Provide vegetative plan, noting all temporary and permanent vegetative practices. Include species, planting dates and seeding, fertilizer, lime, and mulching rates. Vegetative plan shall be site specific for appropriate time of year that seeding will take place and for the appropriate geographic region of Georgia. 12) Provide detailed drawings for all structural practices. Specifications must, at a minimum, meet guidelines set forth in the Manual for Erosion and Sediment Control in Georgia. 13) Clearly note maintenance statement - "Erosion control measures will be maintained at all times. If full implementation of the approved plan does not provide for effective erosion control, additional erosion and sediment control measures shall be implemented to control or treat the sediment source."

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GaSWCC (Amended - 2000)

SECTION II: VEGETATIVE MEASURES

GaSWCC (Amended - 2000)

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GaSWCC (Amended - 2000)

Vegetative Measures
Erosion control should be addressed in the planning stages of all proposed land-disturbing activities. While erosion is difficult to control completely, methods to reduce it are practical, affordable, and cost effective. Erosion control techniques shall be used on all areas exposed for a prolonged period of time, including areas that will be paved or built upon in the future. Various types of vegetative practices are used for erosion control.
The time-line for the implementation of various vegetative practices is as follows:
Mulch, temporary vegetation, or permanent (perennial) vegetation shall be completed on all exposed areas within 14 days after disturbance.
Ds1 - Disturbed Area Stabilization (With Mulching Only) Mulching can be used as a singular erosion control method on areas at rough grade. Mulch can be an option for up to six months provided that the mulch is applied at the appropriate depth (depending on type of mulch used), anchored, and has a continuous 90% cover or greater of the soil surface. Maintenance shall be required to maintain appropriate depth, anchorage, and 90% cover. If an area will remain undisturbed for greater than six months, permanent (perennial) vegetation shall be used.
Ds2 - Disturbed Area Stabilization (With Temporary Seeding) Temporary vegetation may be employed instead of mulch if the area will remain undisturbed for less than six months.
Ds3 - Disturbed Area Stabilization (With Permanent Vegetation) Permanent (perennial) vegetation or sod shall be used immediately on areas at final grade. Permanent (perennial) vegetation shall be used on rough graded areas that will be undisturbed for more than six months.

Ds4 - Disturbed Area Stabilization (With Sodding) may be used in place of Ds3.
"Stabilization" of an area is accomplished when 70 percent of the surface area is covered in a uniform, vegetative cover (permanent or temporary) or anchored mulch of the appropriate thickness with 90% coverage. "Final stabilization" means that all soil disturbing activities at the site have been completed, and that for unpaved areas and areas not covered by permanent structures, at least 70% of the soil surface is uniformly covered in permanent vegetation or equivalent permanent stabilization measures (such as the use of rip rap, gabions, permanent mulches or geotextiles) have been employed.
Permanent (perennial) vegetation shall consist of: planted trees, shrubs, perennial vines; a crop of perennial vegetation appropriate for the time of year and region; or a crop of annual vegetation and a seeding of target crop perennials appropriate for the region, such that within the growing season a 70% coverage by perennial vegetation shall be achieved.
For linear construction projects on land used for agricultural or silvicultural purposes, final stabilization may be accomplished by stabilizing the disturbed land for its agricultural or silvicultural use.
For the purposes of this publication, permanent vegetation is used synonymously with perennial vegetation. Perennial vegetation is plant material that lives continuously from year to year although it may have a dormant season when the leaves and possibly the stems "die back" to the ground. No vegetative planting can technically be considered permanent. Annual vegetation is plant material that lives for only one growing season. This type of vegetation is typically used for temporary establishment due to its quick germination. Some perennial vegetation can be used for temporary stabilization.

GaSWCC (Amended - 2000)

6-17

6-18

GaSWCC (Amended - 2000)

Buffer Zone

Bf

DEFINITION
A strip of undisturbed, original vegetation, enhanced or restored existing vegetation or the re-establishment of vegetation surrounding an area of disturbance or bordering streams, ponds, wetlands, lakes and coastal waters.
PURPOSE
To provide a buffer zone serving one or more of the following purposes:
- Reduce storm runoff velocities
- Act as screen for "visual pollution"
- Reduce construction noise
- Improve aesthetics on the disturbed land
- Filtering and infiltrating runoff
- Cooling rivers and streams by creating shade
- Provide food and cover for wildlife and aquatic organisms
- Flood protection
- Protect channel banks from scour and erosion.
CONDITIONS
A natural strip of vegetation should be preserved and, if needed, supplemented to form the buffer zone. There are two types of buffer zones.
General Buffers
A strip of undisturbed, original land surrounding the disturbed site. It can be useful not only to filter and infiltrate runoff, but also to act as a screen for "visual pollution" and reduce construction noise. General buffers may be enhanced to achieve desired goals.
GaSWCC (Amended - 2000)

Vegetated Stream Buffers
Buffers bordering streams are critical due to the invaluable protection of streams from sedimentation. Stream buffers are also useful in cooling rivers and providing food and cover for wildlife. Refer to the minimum requirements in Act 599 (O.C.G.A. 1-7-1, et. seq.) and Chapters 16 and 18 of the NRCS Engineering Field Handbook.
In most cases, the buffer zone will be incorporated into the permanent vegetative cover. Refer to specification Ds3 - Disturbed Area Stabilization (With Permanent Vegetation).
DESIGN SPECIFICATIONS
Important design factors such as slope, hydrology, width and structure shall be considered. While Georgia's Environmental Protection Division enforces minimum stream buffer requirements, expanding the stream buffer width is always encouraged. If any land-disturbing activity, including exempt and non-exempt practices, occurs within the EPD mandated stream buffers, cut and fills within the buffer shall be stabilized with appropriate matting or blanket.
General Buffers
A width should be selected to permit the zone to serve the purpose(s) as listed above. Supplemental plantings may be used to increase the effectiveness of the buffer zone.
Vegetated Stream Buffers
The structure of vegetated stream buffers should be considered to determine if the buffer must be enhanced to achieve the necessary goals. The size of the stream as well as the topography of the area must be considered to determine the appropriate width of the vegetated stream buffer. A vegetated stream buffer of 50 feet or greater can protect waters from excess sedimentation. The buffer should be increased 2 feet in width for every 1% slope (measured along a line perpendicular to the stream bank). Surface water pollution can be reduced with a 100 foot or wider vegetative buffer.
A general multipurpose riparian buffer consists of three zones.
1. Zone 1 The first 20 feet nearest the stream should consist of trees spaced 6-10 feet apart.
2. Zone 2 The next 10 feet should consist of managed forest.
3. Zone 3 The following 20 feet should be comprised of grasses.
6-19

Wildlife Habitat

Flood Control Sediment Control Nutrient Removal

Streambanks Stabilization and Aquatic Food Web Water Temperature Moderation

0

25

50

75

100

150

200

250

Buffer Width Feet

Figure 6-1.1 - Range of Minimum Width for Meeting Specific Buffer Objectives (Palone and Todd, draft)

This general multipurpose design contains trees and shrubs that help to stabilize stream banks and grasses which spread and reduce the flow from adjacent areas as well as increase settling and infiltration. See Tables 6-1.1 and 6-1.2 for suggested plant species.
If the ideal vegetated buffer width cannot be achieved; narrower buffers can still be used to obtain the goals concerning forest structure and riparian habitat. If this is the case, several design principals should be considered:
1. Sheet flow should be encouraged at the edge of the vegetated stream buffer.
2. The structure of the buffer should consist of under-story and canopy species.
3. The width should be proportional to the watershed area and slope.
4. Native and non-invasive plant species should be used.
5. Density must be considered to determine if the existing buffer must be enhanced to achieve the necessary goals. Vegetation must be dense enough to filter sediment and provide detrital nutrients for aquatic organism.
Streambank stabilization techniques may be required if steep slopes and hydrologic patterns deem it necessary. Refer to specification Sb - Streambank Stabilization (Using Permanent Vegetation). Vegetated stream buffers on steep slopes may need to be wider to effectively filter overland flow. Corridors subject to intense flooding may require additional stream bank stabilization measures.

PLANTING TECHNIQUES
Plantings for buffer re-establishment and enhancement can consist of bare root seedlings, container-grown seedlings, container-grown plants, and balled and burlapped plants. Refer to Tables 6-1.1 and 6-1.2, and Wildlife Plantings in Ds3 - Disturbed Area Stabilization (With Permanent Vegetation). Standard permanent erosion control grasses and legumes may be used in denuded areas for quick stabilization. Refer to specification Ds3 - Disturbed Area Stabilization (With Permanent Vegetation). Availability, cost, associated risk, equipment, planting procedures, and planting density must be considered when choosing planting types.
Soil preparation and maintenance are essential for the establishment of planted vegetation. Soil fertility, weed control, herbaceous cover, as well as additional associated products may be required.
OPERATIONS AND MAINTENANCE
Areas closest to the stream should be maintained with minimal impact.
Watering
During periods of drought as well as during the initial year, watering may be necessary in all buffer areas planted for enhancement.
Weed Control
Weeds can be removed by hand or with careful spraying.

6-20

GaSWCC (Amended - 2000)

Replanting
It is imperative that the structure of the vegetated stream buffer be maintained. If the buffer has been planted, it is suggested that the area be monitored to determine if plant material must be replaced. See Tables 6-1.1 and 6-1.2 for suggested plant species. Provisions for the protection of new plantings from destruction or damage from beavers shall be incorporated into the plan.

Fertilizer If appropriate vegetation is chosen, it is unlikely that
fertilizer will be necessary. Local Contacts:
USDA Natural Resources Conservation Service Georgia Forestry Commission

Table 6-1.1 - Unrooted Hardwood Cuttings

PLANTS SUITABLE FOR USE AS UNROOTED (HARDWOOD) CUTTINGS

Species
Acer negundo Boxelder
Baccharis halimifolia Groundsel bush
Cornus amomum Silky dogwood
Cornus sericia Ssp. slolonifera Red osier dogwood
Crataegus sp. Hawthon
Populus deltoids Eastern cottonwood
Salix sp. interior Sandbar willow
Salix nigra Black willow
Salix purpurea Streamco willow
Salix x colleti Bankers willow
Sambucus canadensis American elderberry
Viburnum denlatum Arrowwood viburnum
Viburnum lentago Nannyberry viburnum

Region

Tolerance To Flooding

C,P,M

H

C,P (lower)

M

P,M

L

Tolerance To Drought
H
M
M

Tolerance To Deposition
H
H
L

Tolerance To Shade
L
L
M

P,M

L

M

H

M

C,P,M

M

H

L

L

C,P,M

M

M

H

L

C,P,M

H

L

H

L

C,P,M

H

H

H

L

C,P,M

H

M

H

L

P,M

H

M

H

L

P,M

H

M

M

M

C,P,M

M

M

M

M

C,P,M

M

M

L

M

Adapted from the USDA/NRCS Engineering Field Handbook, Chapter 18

GaSWCC (Amended - 2000)

6-21

Table 6-1.1 - Unrooted Hardwood Cuttings - continued
Legend: Tolerance to Flooding, Drought, Deposition, and Shade H = High M = Medium L = Low Region C = Coastal P = Piedmont M = Mountain Rooting of all species will be improved if nearby vegetation is pruned to increase sunlight penetration. Whenever possible, harvest hardwood cuttings as close to the repair site as possible. Many of the above grow naturally along streams, in adjacent wetlands, along sewer and power line easements, and where streams enter lakes and along lake shores. Willows generally grow profusely in stormwater detention ponds in urban areas. ALWAYS OBTAIN PERMISSION FROM THE PROPERTY OWNER BEFORE HARVESTING PLANTS!

6-22

GaSWCC (Amended - 2000)

Table 6-1.2 - Native Plant Guide

NATIVE PLANT GUIDE FOR STREAMBANK PLANTING ROOTED STOCK

Species

Region Stream Zone

Wildlife Value

Notes

Acer rubrum Red Maple
Alnus serrulata Smooth alder

M,P,C M,P,C

Amorpha fruticosa False indigo
Aronia arbutifolia Red chokeberry
Asimina triloba Pawpaw
Betula nigra River Burch
Carpinus caroliniana American hornbeam
Carya cordiformis Bitternut hickory
Catalpa bignonioides Catalpa tree
Celtis laevigata Sugarberry
Celtis occidentalis Hackberry
Cephalantus Occidentalis Buttonbush

M,P,C M,P,C M,P,C M,P,C M,P,C
P,C P,C P,C P,C M,P,C

Chionanthus virginicus

Fringe tree

P,C

Clethra alnifolia

Sweet pepperbush

P,C

Cornus amomum

Silky dogwood

M,P

Tree Shrub
Shrub Shrub Tree Tree Tree Tree Tree Tree Tree Shrub
Tree Shrub
Shrub

High Seeds & browse
Moderate, Cover

Rapid growth.
Rapid growth. Stabilizes streambanks. Sun.

Moderate
Moderate Cover & Food
Important food for fox & possum
Good for cavity nester

Sun. Rhizomatous Colonial Shrub.
Full sun.

Low

Partial shade.

Moderate, food

Wet bottoms.

Unknown

High food cover

Partial shade.

High

Partial shade.

Moderate, ducks & Shorebirds are users. Nectar for hummingbirds.

Sun.

Moderate
Moderate
High, songbirds, Mammals

Tolerant of shade.
Partial shade. Good landscape value.
Shade tolerant. Good bank stabilizer.

GaSWCC (Amended - 2000)

6-23

Species

Table 6-1.2 - Native Plant Guide - continued
Region Stream Zone Wildlife Value

Notes

Cornus stricta Swamp dogwood
Cornus florida Flowering dogwood
Cyrilla racemiflora Titi
Diospyros Virginia Persimmon
Fraxinus caroliniana Carolina ash

M,P M,P,C
C M,P,C
C

Fraxinus pennsylvanica Green ash

M,P,C

Gleditsia aquatica

Water locust

P,C

Gleditsia triacanthos

Honey locust

P,C

Hibiscus aculeatus

Hibiscus

Comfort root

C

Hibiscus militaris Hibiscus Halberd-leaved Marshmallow C

Hibiscus lasiocarpus

Hibiscus

C

Hibiscus moscheutos

Hibiscus

C

Ilex coriacea

Sweet Gallberry

C

Ilex decidua

Possumhaw

P,C

Ilex glabra

Bitter gallberry or Inkberry

C

Shrub Tree Tree Tree Tree
Tree Tree Tree
Shrub
Shrub
Shrub
Shrub Shrub Shrub Shrub

High High, birds, food Low Extremely high Mammals Moderate
Low Low Low
Unknown
Unknown
Unknown
Unknown Unknown High, food, nest sites High

Good bank stabilizer in shade.
Shade tolerant.
Light shade.
Not shade tolerant. Rapid growing. Streambank grower. Sun to partial shade. Rapid grower. Full sun.
Sun.
Full sun, thorns. Use on open level floodplain areas & Depressions in C. Use on open level floodplain areas & Depressions in C. Use on open level floodplain areas & Depressions in C. Use on open level floodplain areas & Depressions in C.
Sun or shade. Stoloniferous. Sun to some shade.

6-24

GaSWCC (Amended - 2000)

Species

Table 6-1.2 - Native Plant Guide - continued
Region Stream Zone Wildlife Value

Notes

Ilex opaca American holly
Ilex verticilata Winterberry
Ilex vomitoria Yaupon
Juglans nigra Black walnut
Juniperus virginiana Eastern red cedar
Leucothoe axillaris Leucothoe
Lindera benzoin Common spicebush
Liriondendron tulipefera Tulip poplar
Liquidambar styraciflua Sweetgum
Lyonia lucida Lyonia or Fetterbush
Magnolia Virginia Sweetbay
Myrica cerifera Southern wax myrtle
Nyssa ogeche Ogeechee lime
Nyssa sylvatica Blackgum or sourgum
Nyssa aquatica Swamp tupelo
Ostrya Virginiana Hophornbeam

M,P,C
M,P C
M,P M,P,C
C M M,P M,P,C C P,C C C M,P,C C M,P,C

Tree
Shrub Shrub
Tree Tree Shrub Shrub Tree Tree Shrub Tree Shrub Tree Tree Tree Tree

High, food, cover nests High, cover & fruit for birds. Holds berries in winter.
High, songbirds
Good
High, food

Prefers shade.
Full sun to some shade. Seasonally flooded areas.
Small tree, very adaptable, suckers.
Temporarily flooded wetlands along floodplains.
Tolerant to some shade in youth.

Low High, songbirds Low

Partial shade.
Shade, acidic soils. Good understory.
Tolerant to partial Shade.

Low

Partial shade.

Low

Sun.

Very low

Shade tolerant.

Moderate High, fruit, Cavity nesters
Moderate, seeds

Light shade.
Wetland tree Sun to partial shade.

High Moderate

Prefers shade.
Tolerant of all sunlight conditions.

GaSWCC (Amended - 2000)

6-25

Species

Table 6-1.2 - Native Plant Guide - continued
Region Stream Zone Wildlife Value

Notes

Persea borbonia

Red bay

C

Pinus taeda

Loblolly pine

P,C

Platanus occidentalis Sycamore
Populus deltoides Eastern cottonwood
Quercus alba White oak
Quercus laurifolia Swamp laurel oak
Quercus lyrata Overcup oak
Quercus michauxii Swamp chestnut oak
Quercus nigra Water oak
Quercus pagoda Cherrybark oak
Quercus phellos Willow oak
Quercus shumardii Shumard oak
Salix nigra Black willow
Rhododendron atlanticum Coast azelea
Rhododendron viscosum Swamp azelea
Styrax american

M,P,C M,P,C M,P,C
C P,C M,P,C M,P,C M,P M,P,C P,C M,P,C P,C C C

Tree Tree
Tree Tree Tree Tree Tree Tree Tree Tree Tree Tree Shrub & Tree Shrub Shrub Shrub

Good food, for quail and bluebirds. Understory tree.

Moderate
Low. Cavity Nesters
High
High, food

Poor sites.
Transplants well. Rapid growth in full sun.
Invasive roots. Rapid growth.
Prefers moist well drained soil.

High

High High

Sloughs & bottoms.
Wetter sites than white oak.

High

High

High, mast

Full to partial sun.

High Nesting Very low

Rapid growth, full sun.
Very fragrant, Suckers.

Low Unknown

6-26

GaSWCC (Amended - 2000)

Species

Table 6-1.2 - Native Plant Guide - continued
Region Stream Zone Wildlife Value

Notes

Taxodium distichum Bald cypress
Tsuga canadensis Eastern hemlock
Viburnum nudum Swamp haw

C M M,P,C

Tree Tree Shrub

Good perching site Moderate

Full sun.
Tolerates all light conditions.

High

Shade tolerant

Legend:

Region M = Mountains P = Piedmont C = Coastal Plain

Plant List Sources:

Brown, Claude L. & Kirkman, Katherine L. 1990. Trees of Georgia and Adjacent States.

Foote, Leonard E. & Jones, Samuel B., Jr. 1989. Native Shrubs and Woody Vines of the Southeast.

Georgia Cooperative Extension Service. Native Plants for Georgia Gardens.

Hightshoe, Gary L. 1988. Native Trees, Shrubs and Vines for Urban & Rural America.

USDA Natural Resources Conservation Service. 1973. Seacoast Plants of the Carolinas.

USDA Natural Resources Conservation Service, Engineering Field Handbook, Chapter 18, Soil Bioengineering for Upland Slope Protection and Erosion Reduction.

GaSWCC (Amended - 2000)

6-27

6-28

GaSWCC (Amended - 2000)

Coastal Dune Stabilization

(With Vegetation)

Cs

DEFINITION
Planting vegetation on dunes that are denuded, artificially constructed, or renourished.
PURPOSE
- To stabilize soil on dunes allowing them to become more resistant to wind and waves.
- To allow development of dunes in areas where they have been damaged or destroyed.
CONDITIONS
On bare or sparsely vegetated dunes or areas where dune development is desired.
PLANNING CONSIDERATIONS
Coastal beaches are subject to regulation from a variety of Federal, State, and local agencies. Permits must be requested and granted by all appropriate jurisdictions before work is performed.
Coastal areas are affected by many dynamic systems. Detailed studies are often required to determine the possible effects that may result from dune modifications. Environmental assessments are generally required including public review and comment.
Protection of dunes from human and vehicular traffic is essential if vegetation is to succeed. Crosswalks or crossover structures should be planned to provide beach access.
Plant species that are native to coastal areas should be used whenever possible.
GaSWCC (Amended - 2000)

An irrigation system will be required during the first growing season in order to obtain good survival.
Common Commercially Available Plants
Marshhay cordgrass (Spartina patens) "Flageo" variety (or native collections) is a perennial grass that occurs on dunes throughout the South Atlantic and Gulf region and in Puerto Rico. It is the dominant plant on dunes composed of broken shale and coquina rock along the northern Florida coast. The grass is especially tolerant of salt.
Stems are slender and grow two to three feet tall. Leaves are rolled inward and resemble rushes. Seed heads are composed of two to several compressed spikes attached at about 90 degrees to the culm. Plants spread by means of a network of slender rhizomes.
Plantings of vegetative material in early spring are most successful. Bare root or potted planting stock is recommended for large plantings. Stems rooted at the base can be planted at a depth of four to five inches deep. Plants that have developed rhizomes are preferred for planting stock.
Bitter panicum (Panicum amarum) is a perennial grass found on dunes throughout the South Atlantic and Gulf regions. It is most common in South Florida and Texas.
Plants grow to an average height of three to four feet tall. Leaves are smooth and bluish green in color. Seed heads are narrow, compressed, and generally are sparsely seeded. Plants spread from a very aggressive, scattered system of rhizomes, but stands are rather open.
Bitter panicum produces few viable seed but is easier to transplant than sea oats. They can be propagated from a stem with part of the rhizome attached or from rhizomes that are eight to twelve inches long. Plant rhizomes about four inches deep in early spring.
Plants may be propagated by removing all of the stem from robust plants and placing them in the dune at an angle of about 45 degrees. Several nodes should be buried. Spacing should be no more than six feet apart.
Coastal Panicgrass (Panicum amarum v. amaralum) is a somewhat dense, upright perennial bunchgrass found on coastal dunes throughout the South Atlantic and Gulf area. It is the dominant plant at many locations in West Florida, Alabama, and Texas.
The stems are coarse, straight, stiff, and up to four feet tall. Partially compressed seed heads produce moderate amounts of viable seed each fall. The crowns enlarge slowly from short, almost vertical tillers.
6-29

Plant seed one to three inches deep in the spring and mulch the area. Seedling survival depends on moisture after germination. Clumps of coastal panicgrass can be dug, divided and planted during rainy seasons or when irrigation is available.

Planting Requirements for Native Plants

Species

Stock Date Depth

Marshhay Cordgrass

(Spartina patens)

Plants Spring 4"-5"

Bitter Panicum (Panicum amarum) Rhizomes Spring

Abt 4"

Coastal Panigrass

(Panicum ararum v. Seeds or

amaralum)

plants Spring 1"-3"

Sand Fence Use In Building Dunes
Sand fence may be used to build sand dunes when sand is available. Costs are usually higher but dune development is faster when compared to vegetation alone and generally less expensive than building dunes with machinery.
To form a barrier dune, construct sand fences a minimum of 100 feet from the mean high tide line. Two or more parallel fences spaced from 30 to 40 feet apart are needed. Locate fences as near as possible to a 90 degree angle with the prevailing winds, but as near parallel to the water line as possible.
Where winds are generally parallel with the water line, a single line of fence may be constructed at least 140 feet from the mean high tide. Construct short sections of fence (approximately 30 feet long) parallel to the prevailing wind and approximately perpendicular to the original fence. Place these fences opposite the water side and space these fences about 40 feet apart.
As sand collects over the fence, additional fence can be constructed over the original fence until the desired height is obtained.
Old dunes may be widened by constructing sand fence about 15 feet to the seaward side of the base of the old dune.
Vegetation must be established following development of dunes, or allowed to develop from existing stands as dunes develop.
SPECIFICATIONS
Sand Fence Specifications
Use standard commercial 4-foot high snow fence that consists of wooden slats wired together with spaces

6-30

Figure 6-2.1 - Sand Fence and Native Plants
between the slats. Distance between slats is approximately equal to the slat width, or generally 1 1/4 inches. Slats will be made from grade A or better spruce. Slats will be woven between five two-wire cables of copperbearing, galvanized wire. Slats will be dipped in a red oxide, weather resistant stain. The fence must be sound, free of decay, broken wire or missing or broken slats.
Fence will be supported by black locust, red cedar, or white cedar posts. Other wood of equal life or strength may be used. Posts will be a minimum of 7 feet with a minimum diameter of three inches. Posts will be spaced no farther than 10 feet apart.
Four wire ties will be used to fasten fence to posts. Weave fence between posts so that every other post will be attached on the ocean side of posts. Tie wires will be no smaller than 12-gauge galvanized wire.
Posts will be set in holes at least three feet deep.
Three or four rows of fence should be used if sufficient land area and sand are available.
MAINTENANCE
Maintaining Dunes
A strong, uniform dune line must be maintained to provide maximum protection from wind and water. Blowouts, wash pits, or other natural or man-made damage must be repaired quickly to prevent weakening of the entire system. Blow-outs in a dune system can be repaired by placing sand fence between existing dunes. One or more fences may be required. It is essential to tie the ends of the fence into the existing dune to keep the wind from slipping around the ends. Maintain fences, and erect additional fences if needed, until the eroding area is replenished to the desired height and permanently stabilized.
GaSWCC (Amended - 2000)

Foot and vehicular traffic must be controlled or prohibited on dunes to maintain vegetation and prevent excessive sand movement. Elevated walks, semi-permanent paved paths, and portable roll-up walkways are satisfactory. Walkways should be curved to reduce wind movement. Both inland and secondary dunes must be protected from traffic.
Vegetative Maintenance
Plantings are maintained with applications of fertilizer to keep desired density of plants. Annual application of about 50 pounds of nitrogen per acre should be applied. Where vegetation has been destroyed, replanting should be considered.

Black Locust, Red or White Cedar or similarly durable wood
4 12-gauge galvanized wires

s1p0a'cminagx.

leGvreolund

3" minimum post diameter

3' min. 7' min. length

Figure 6-2.2 - Sand Fence Installation Requirements

GaSWCC (Amended - 2000)

6-31

6-32

GaSWCC (Amended - 2000)

Disturbed Area Stabilization (With Mulching Only) Ds1
DEFINITION
Applying plant residues or other suitable materials, produced on the site if possible, to the soil surface.
PURPOSE
- To reduce runoff and erosion - To conserve moisture - To prevent surface compaction or crusting - To control undesirable vegetation - To modify soil temperature - To increase biological activity in the soil
REQUIREMENT FOR REGULATORY COMPLIANCE
Mulch or temporary grassing shall be applied to all exposed areas within 14 days of disturbance. Mulch can be used as a singular erosion control device for up to six months, but it shall be applied at the appropriate depth, depending on the material used, anchored, and have a continuous 90% cover or greater of the soil surface. Maintenance shall be required to maintain appropriate depth and 90% cover. Temporary vegetation may be employed instead of mulch if the area will remain undisturbed for less than six months. If an area will remain undisturbed for greater than six months, permanent vegetative techniques shall be employed. Refer to Ds2 -Disturbed Area Stabilization (With Temporary Seeding), Ds3 - Disturbed Area Stabilization (With Permanent Seeding), and Ds4 - Disturbed Area Stabilization (With Sodding).
GaSWCC (Amended - 2000)

SPECIFICATIONS
MULCHING WITHOUT SEEDING
This standard applies to grades or cleared areas where seedings may not have a suitable growing season to produce an erosion retardant cover, but can be stabilized with a mulch cover.
Site Preparation
1. Grade to permit the use of equipment for applying and anchoring mulch.
2. Install needed erosion control measures as required such as dikes, diversions, berms, terraces and sediment barriers.
3. Loosen compact soil to a minimum depth of 3 inches.
Mulching Materials
Select one of the following materials and apply at the depth indicated:
1. Dry straw or hay shall be applied at a depth of 2 to 4 inches providing complete soil coverage. One advantage of this material is easy application.
2. Wood waste (chips, sawdust or bark) shall be applied at a depth of 2 to 3 inches. Organic material from the clearing stage of development should remain on site, be chipped, and applied as mulch. This method of mulching can greatly reduce erosion control costs.
3. Cutback asphalt (slow curing) shall be applied at 1200 gallons per acre (or 1/4 gallon per sq. yd.).
4. Polyethylene film shall be secured over banks or stockpiled soil material for temporary protection. This material can be salvaged and reused.
Applying Mulch
When mulch is used without seeding, mulch shall be applied to provide full coverage of the exposed area.
1. Dry straw or hay mulch and wood chips shall be applied uniformly by hand or by mechanical equipment.
6-33

2. If the area will eventually be covered with perennial vegetation, 20-30 pounds of nitrogen per acre in addition to the normal amount shall be applied to offset the uptake of nitrogen caused by the decomposition of the organic mulches.
3. Cutback asphalt shall be applied uniformly. Care should be taken in areas of pedestrian traffic due to problems of `tracking in" or damage to shoes, clothing, etc.
4. Apply polyethylene film on exposed areas.
Anchoring Mulch
1. Straw or hay mulch can be pressed into the soil with a disk harrow with the disk set straight or with a special "packer disk." Disks may be smooth or serrated and should be 20 inches or more in diameter and 8 to 12 inches apart. The edges of the disk should be dull enough not to cut the mulch but to press it into the soil leaving much of it in an erect position. Straw or hay mulch shall be anchored immediately after application.
Straw or hay mulch spread with special blower-type equipment may be anchored with emulsified asphalt (Grade AE-5 or SS-1). The asphalt emulsion shall be sprayed onto the mulch as it is ejected from the machine. Use 100 gallons of emulsified asphalt and 100 gallons of water per ton of mulch. Tackifers and binders can be substituted for emulsified asphalt. Please refer to specification Tb Tackifers and Binders. Plastic mesh or netting with mesh no larger than one inch by one inch shall be installed according to manufacturer's specifications.
2. Netting of the appropriate size shall be used to anchor wood waste. Openings of the netting shall not be larger than the average size of the wood waste chips.
3. Polyethylene film shall be anchor trenched at the top as well as incrementally as necessary.
6-34

GaSWCC (Amended - 2000)

Disturbed Area Stabilization (With Temporary Seeding)
Ds2
DEFINITION
The establishment of temporary vegetative cover with fast growing seedings for seasonal protection on disturbed or denuded areas.
PURPOSE
- To reduce runoff and sediment damage of down stream resources
- To protect the soil surface from erosion - To improve wildlife habitat - To improve aesthetics - To improve tilth, infiltration and aeration as well as
organic matter for permanent plantings.
REQUIREMENT FOR REGULATORY COMPLIANCE
Mulch or temporary grassing shall be applied to all exposed areas within 14 days of disturbance. Temporary grassing, instead of mulch, can be applied to rough graded areas that will be exposed for less than six months. If an area is expected to be undisturbed for longer than six months, permanent perennial vegetation shall be used. If optimum planting conditions for temporary grassing is lacking, mulch can be used as a singular erosion control device for up to six months but it shall be applied at the appropriate depth, anchored, and have a continuous 90% cover or greater of the soil surface. Refer to specification Ds1-Disturbed Area Stabilization (With Temporary Seeding).

CONDITIONS
Temporary vegetative measures should be coordinated with permanent measures to assure economical and effective stabilization. Most types of temporary vegetation are ideal to use as companion crops until the permanent vegetation is established. Note: Some species of temporary vegetation are not appropriate for companion crop plantings because of their potential to out-compete the desired species (e.g. annual ryegrass). Contact NRCS or the local SWCD for more information.
SPECIFICATIONS
Grading and Shaping
Excessive water run-off shall be reduced by properly designed and installed erosion control practices such as closed drains, ditches, dikes, diversions, sediment barriers and others.
No shaping or grading is required if slopes can be stabilized by hand-seeded vegetation or if hydraulic seeding equipment is to be used.
Seedbed Preparation
When a hydraulic seeder is used, seedbed preparation is not required. When using conventional or handseeding, seedbed preparation is not required if the soil material is loose and not sealed by rainfall.
When soil has been sealed by rainfall or consists of smooth cut slopes, the soil shall be pitted, trenched or otherwise scarified to provide a place for seed to lodge and germinate.
Lime and Fertilizer
Agricultural lime is required unless soil tests indicate otherwise. Apply agricultural lime at a rate of one ton per acre. Graded areas require lime application. Soils can be tested to determine if fertilizer is needed. On reasonably fertile soils or soil material, fertilizer is not required. For soils with very low fertility, 500 to 700 pounds of 10-10-10 fertilizer or the equivalent per acre (12-16 lbs./1,000 sq. ft.) shall be applied. Fertilizer should be applied before land preparation and incorporated with a disk, ripper or chisel.
Seeding
Select a grass or grass-legume mixture suitable to the area and season of the year. Seed shall be applied uniformly by hand, cyclone seeder, drill, culti-packer-

GaSWCC (Amended - 2000)

6-35

seeder, or hydraulic seeder (slurry including seed and fertilizer). Drill or cultipacker seeders should normally place seed one-quarter to one-half inch deep. Appropriate depth of planting is ten times the seed diameter. Soil should be "raked" lightly to cover seed with soil if seeded by hand.
Mulching
Temporary vegetation can, in most cases, be established without the use of mulch. Mulch without seeding should be considered for short term protection. Refer to Ds1 - Disturbed Area Stabilization (With Mulching Only).
Irrigation
During times of drought, water shall be applied at a rate not causing runoff and erosion. The soil shall be thoroughly wetted to a depth that will insure germination of the seed. Subsequent applications should be made when needed.

6-36

GaSWCC (Amended - 2000)

GaSWCC (Amended - 2000)

Table 6-4.1 - Temporary Cover or Companion Crops 1/ PLANT, PLANTING RATES, AND PLANTING DATED FOR TEMPORARY COVER OR COMPANION CROPS 1/

Species

Broadcast

Rates 2/ - PLS 3/

Per

Per

Acre

1000

sq. ft.

BARLEY (Horduem vulgare)
alone in mixture
LESPEDEZA, ANNUAL (Lespedeza striata)
alone in mixtures
LOVEGRASS, WEEPING (Eragrostis curvula)
alone in mixtures
MILLET, BROWNTOP (Panicum fasciculatum)
alone in mixtures

3 bu. (144 lbs.)
1/2 bu. (24 lbs.)
40 lbs. 10 lbs.
4 lbs. 2 lbs.
40 lbs. 10 lbs.

C 3.3 lb. 0.6 lb.
0.9 lb. 0.2 lb.
0.1 lb. 0.05 lb.
C 0.9 lb. 0.2 lb.

Resource Area 4/

Planting Dates by Resource Areas Planting Dates
(Solid lines indicate optimum dates, dotted lines indicate permissible but marginal dates.)

J F M A M J J ASO N D

M-L

....

....

P

.......

...........

......

Remarks
14,000 seed per pound. Winterhardy. Use on productive soils.

J F M A M J J ASO N D

M-L

....... .......

P

...... .......

C

..... ....

200,000 seed per pound. May volunteer for several years. Use inoculant EL.

J F M A M J J ASO N D

M-L

.......

....

P

......

....

C

......

.....

1,500,000 seed per pound. May last for several years. Mix with Sericea lespedeza.

J F M A M J J ASO N D

M-L

....

....

P

....

......

....

.....

137,000 seed per pound. Quick dense cover. Will provide too much competition in mixtures if seeded at high rates.

6-37

6-38

Table 6-4.1 - Temporary Cover or Companion Crops 1/ - continued PLANT, PLANTING RATES, AND PLANTING DATED FOR TEMPORARY COVER OR COMPANION CROPS 1/

Species
MILLET, PEARL (Pennesetum glaucum)
alone OATS (Avena sativa)
alone in mixtures RYE (Secale cereale) alone in mixture RYEGRASS, ANNUAL (Lolium temulentum) alone SUDANGRASS (Sorghum Sudanese) alone

Broadcast

Rates 2/ - PLS 3/

Per

Per

Acre

1000

sq. ft.

50 lbs.

1.1 lb.

4 bu. (128 lbs.)
1 bu. (32 lbs.)

2.9 lb. 0.7 lb.

3 bu. (168 lbs.)
1/2 bu. (28 lbs.)
40 lbs.

3.9 lb. 0.6 lb.
C 0.9 lb.

60 lbs.

1.4 lb

Resource Area 4/

Planting Dates by Resource Areas Planting Dates
(Solid lines indicate optimum dates, dotted lines indicate permissible but marginal dates.)

J F M A M J J ASO N D

M-L

...

...

P

....

.......

C

...

....

J F M A M J J ASO N D

M-L

...

...

P

...

...

C

...

...

Remarks
88,000 seed per pound. Quick dense cover. May reach 5 feet in height. Not recommended for mixtures.
13,000 seed per pound. Use on productive soils. Not as winterhardy as rye or barley.

J F M A M J J ASO N D

M-L

P

C

..............

....... ...... ......

........ ......

18,000 seed per pound. Quick cover. Drought tolerant and winterhardy.

J F M A M J J ASO N D

M-L

.............................

....

............

P

.........................

......

... 227,000 seed per pound.

......................

......

Dense cover. Very competitive

and is not to be used in mixtures.

J F M A M J J ASO N D

M-L

......

......

P

......

......

C

......

55,000 seed per pound. Good on droughty sites. Not recommended for mixtures.

GaSWCC (Amended - 2000)

GaSWCC (Amended - 2000)

Table 6-4.1 - Temporary Cover or Companion Crops 1/ - continued PLANT, PLANTING RATES, AND PLANTING DATED FOR TEMPORARY COVER OR COMPANION CROPS 1/

Species
TRITICALE (X-Triticosecale)
alone in mixtures
WHEAT (Triticum Aestivum)
alone in mixtures

Broadcast

Rates 2/ - PLS 3/

Per

Per

Acre

1000

sq. ft.

3 bu. (144 lbs.)
1/2 bu. (24 lbs.)

3.3 lb. 0.6 lb.

3 bu. (180 lbs.)
1/2 bu. (30 lbs.)

4.1 lb. 0.7 lb.

Resource Area 4/

Planting Dates by Resource Areas Planting Dates
(Solid lines indicate optimum dates, dotted lines indicate permissible but marginal dates.)

J F M A M J J ASO N D

C

.......

.... ...

.....

Remarks

Use on lower part of Southern Coastal Plain and in Atlantic Coastal Flatwoods only.

J F M A M J J ASO N D

M-L

P

C

......

.... .......
......

....... ... 15,000 seed per pound.

1/ Temporary cover crops are very competitive and will crown out perennials if seeded too heavily. 2/ Reduce seeding rates by 50% when drilled. 3/ PLS is an abbreviation for Pure Live Seed. 4/ M-L represents the Mountain; Blue Ridge; and Ridges and Valleys MLRAs
P represents the Southern Piedmont MLRA C represents Southern Coastal Plain; Sand Hills; Black Lands; and Atlantic Coast Flatwoods MLRAs (See Figure 6-4.1, p. 6-40).

6-39

Major Land Resource Areas (MLRA) of Georgia

Mountain, Blue Ridge, and Ridges and Valley

Dade

Catoosa

Walker

Whitfield Murray

Chattooga

Gordon

Floyd

Bartow

Fannin Gilmer Pickens
Cherokee

Towns Union

Rabun

Habersham

White Lumpkin

Stephens

Dawson

Hall

Banks Franklin

Forsyth

Hart

Southern Piedmont
Southern Coastal Plain, Sand Hills, Black Lands, and Atlantic Coastal Flatwoods

Jackson

Madison

Elbert

Polk Haralson

Paulding

Cobb

Douglas Fulton

Gwinnett Barrow

Dekalb

Walton

Clarke Oglethorpe
Oconee

Wilkes

Lincoln

Rockdale

Carroll Heard

Coweta

Clayton

Fayette

Henry

Spalding

Newton

Morgan

Greene Teliaferro

Columbia

Butts Jasper

Putnam

Hancock

Warren McDuffie Glascock

Richmond

Troup

Meriwether

Pike Lanier Upson

Monroe

Jones

Baldwin

Washington

Jefferson

Burke

Harris

Talbot

Muscogee

Taylor

Bibb Crawford
Peach

Wilkinson Twiggs

Johnson

Jenkins Screven Emanuel

Marion Chattahoochee

Macon

Houston Bleckley

Laurens

Treutlen

Bulloch Chandler

Effingham

Montgomery

Schley

Stewart Webster

Sumter

Quitman

Randolph Terrell

Lee

Clay

Calhoun

Dougherty

Dooly

Pulaski

Dodge

Crisp

Wilcox

Turner Worth
Tift

Ben Hill Irwin

Wheeler Telfair

Toombs

Evans

Tattnall

Jeff Davis

Appling

Long

Coffee

Bacon

Wayne

Bryan Liberty
McIntosh

Early

Baker

Berrien Atkinson

Miller

Mitchell

Colquitt

Cook

Seminole

Decatur

Grady

Thomas

Brooks

Lanier

Clinch

Lowndes

Echols

Pierce

Ware

Brantley

Glynn

Charlton

Camden

Chatham

6-40

Figure 6-4.1

GaSWCC (Amended - 2000)

Disturbed Area Stabilization (With Permanent Vegetation)
Ds3
DEFINITION
The planting of perennial vegetation such as trees, shrubs, vines, grasses, or legumes on exposed areas for final permanent stabilization. Permanent perennial vegetation shall be used to achieve final stabilization.
PURPOSE
- To protect the soil surface from erosion - To reduce damage from sediment and runoff to
down-stream areas - To improve wildlife habitat and visual resources - To improve aesthetics
REQUIREMENT FOR REGULATORY COMPLIANCE
This practice shall be applied immediately to rough graded areas that will be undisturbed for longer than six months. This practice or sodding shall be applied immediately to all areas at final grade. Final Stabilization means that all soil disturbing activities at the site have been completed, and that for unpaved areas and areas not covered by permanent structures, at least 70% of the soil surface is uniformly covered in permanent vegetation or equivalent permanent stabilization measures (such as the use of rip rap, gabions, permanent mulches or geotextiles) have been employed. Permanent vegetation shall consist of: planted trees, shrubs, perennial vines; a crop of perennial vegetation appropriate for the region, such that within the growing season a 70% coverage by perennial vegetation shall be achieved. Final stabilization applies to each phase of construction. For linear construction projects on land used for agricultural or silvicultural purposes, final sta-
GaSWCC (Amended - 2000)

bilization may be accomplished by stabilizing the disturbed land for its agricultural or silvicultural use. Until this standard is satisfied and permanent control measures and facilities are operational, interim stabilization measures and temporary erosion and sedimentation control measures shall not be removed.
CONDITIONS
Permanent perennial vegetation is used to provide a protective cover for exposed areas including cuts, fills, dams, and other denuded areas.
PLANNING CONSIDERATIONS
1. Use conventional planting methods where possible.
2. When mixed plantings are done during marginal planting periods, companion crops shall be used.
3. No-till planting is effective when planting is done following a summer or winter annual cover crop. Sericea lespedeza planted no-till into stands of rye is an excellent procedure.
4. Block sod provides immediate cover. It is especially effective in controlling erosion adjacent to concrete flumes and other structures. Refer to Specification Ds4-Disturbed Area Stabilization (With Sodding).
5. Irrigation should be used when the soil is dry or when summer plantings are done.
6. Low maintenance plants, as well as natives, should be used to ensure long-lasting erosion control.
7. Mowing should not be performed during the quail nesting season (May to September).
8. Wildlife plantings should be included in critical area plantings.
Wildlife Plantings
Commercially available plants beneficial to wildlife species include the following:
Mast Bearing Trees
Beech, Black Cherr y, Blackgum, Chestnut, Chinkapin, Hackberry, Hickory, Honey Locust, Native Oak, Persimmon, Sawtooth Oak and Sweetgum.
All trees that produce nuts or fruits are favored by many game species. Hickory provides nuts used mainly by squirrels and bear.
6-41

Shrubs and Small Trees
Bayberry, Bicolor Lespedeza, Crabapple, Dogwood, Huckleberry or Native Blueberry, Mountain Laurel, Native Holly, Red Cedar, Red Mulberry, Sumac, Wax Myrtle, Wild Plum and Blackberry.
Plant in patches without tall trees to develop stable shrub communities. All produce fruits used by many kinds of wildlife, except for lespedeza which produces seeds used by quail and songbirds.
Grasses, Legumes, Vines and Temporary Cover
Bahiagrass, Bermudagrass, Grass-Legume mixtures, Partridge Pea, Annual Lespedeza, Orchardgrass (for mountains), Browntop Millet (for temporary cover), and Native grapes.
Provides herbaceous cover in clearings for a game bird brood-rearing habitat. Appropriate legumes such as vetches, clovers, and lespedezas may be mixed with grass, but they may die out after a few years.
CONSTRUCTION SPECIFICATIONS
Grading and Shaping
Grading and shaping may not be required where hydraulic seeding and fertilizing equipment is to be used. Vertical banks shall be sloped to enable plant establishment.
When conventional seeding and fertilizing are to be done, grade and shape where feasible and practical, so that equipment can be used safely and efficiently during seedbed preparation, seeding, mulching and maintenance of the vegetation.
Concentrations of water that will cause excessive soil erosion shall be diverted to a safe outlet. Diversions and other treatment practices shall conform with the appropriate standards and specifications.
Lime and Fertilizer Rates and Analysis
Agricultural lime is required at the rate of one to two tons per acre unless soil tests indicate otherwise. Graded areas require lime application. If lime is applied within six months of planting permanent perennial vegetation, additional lime is not required. Agricultural lime shall be within the specifications of the Georgia Department of Agriculture.
Lime spread by conventional equipment shall be "ground limestone." Ground limestone is calcitic or dolomitic limestone ground so that 90 percent of the ma-
6-42

terial will pass through a 10-mesh sieve, not less than 50 percent will pass through a 50-mesh sieve and not less than 25 percent will pass through a 100-mesh sieve.
Agricultural lime spread by hydraulic seeding equipment shall be "finely ground limestone." Finely ground limestone is calcitic or dolomitic limestone ground so that 98 percent of the material will pass through a 20mesh sieve and not less than 70 percent will pass through a 100-mesh sieve.
It is desirable to use dolomitic limestone in the Sand Hills, Southern Coastal Plain and Atlantic Coast Flatwoods MLRAs. (See Figure 6-4.1)
Agricultural lime is generally not required where only trees are planted.
Initial fertilization, nitrogen, topdressing, and maintenance fertilizer requirements for each species or combination of species are listed in Table 6-5.1.
Lime and Fertilizer Application
When hydraulic seeding equipment is used, the initial fertilizer shall be mixed with seed, innoculant (if needed), and wood cellulose or wood pulp fiber mulch and applied in a slurry. The innoculant, if needed, shall be mixed with the seed prior to being placed into the hydraulic seeder. The slurry mixture will be agitated during application to keep the ingredients thoroughly mixed. The mixture will be spread uniformly over the area within one hour after being placed in the hydroseeder.
Finely ground limestone will be mixed with water and applied immediately after mulching is completed or in combination with the top dressing.
When conventional planting is to be done, lime and fertilizer shall be applied uniformly in one of the following ways:
1. Apply before land preparation so that it will be mixed with the soil during seedbed preparation.
2. Mix with the soil used to fill the holes, distribute in furrows.
3. Broadcast after steep surfaces are scarified, pitted or trenched.
4. A fertilizer pellet shall be placed at root depth in the closing hole beside each pine tree seedling.
GaSWCC (Amended - 2000)

Plant Selection
Refer to Tables 6-4.1, 6-5.2, 6-5.3 and 6-5.4 for approved species. Species not listed shall be approved by the State Resource Conservationist of the Natural Resources Conservation Service before they are used.
Plants shall be selected on the basis of species characteristics, site and soil conditions, planned use and maintenance of the area; time of year of planting, method of planting; and the needs and desires of the land user.
Some perennial species are easily established and can be planted alone. Examples of these are Common Bermuda, Tall Fescue, and Weeping Lovegrass.
Other perennials, such as Bahia Grass and Sericea Lespedeza, are slow to become established and should be planted with another perennial species. The additional species will provide quick cover and ample soil protection until the target perennial species become established. For example, Common seeding combinations are 1) Weeping Lovegrass with Sericea Lespedeza (scarified) and 2) Tall Fescue with Sericea Lespedeza (unscarified).
Plant selection may also include annual companion crops. Annual companion crops should be used only when the perennial species are not planted during their optimum planting period. A common mixture is Brown Top Millet with Common Bermuda in mid-summer. Care should be taken in selecting companion crop species and seeding rates because annual crops will compete with perennial species for water, nutrients, and growing space. A high seeding rate of the companion crop may prevent the establishment of perennial species.
Ryegrass shall not be used in any seeding mixtures containing perennial species due to its ability to out-compete desired species chosen for permanent perennial cover.
Seed Quality
The term "pure live seed" is used to express the quality of seed and is not shown on the label. Pure live seed, PLS, is expressed as a percentage of the seeds that are pure and will germinate. Information on percent germination and purity can be found on seed tags. PLS is determined by multiplying the percent of pure seed with the percent of germination; i.e.,
(PLS = % germination x % purity)
EXAMPLE:
Common bermuda seed 70% germination, 80% purity
PLS = 70% germination x 80% purity
PLS = 56%
GaSWCC (Amended - 2000)

The percent of PLS helps you determine the amount of seed you need. If the seeding rate is 10 pounds PLS and the bulk seed is 56 % PLS, the bulk seeding rate is:
10 lbs. PLS/acre = 17.9 lbs/acre 56% PLS
You would need to plant 17.9 lbs/acre to provide 10 lbs/acre of pure live seed.
Seedbed Preparation
Seedbed preparation may not be required where hydraulic seeding and fertilizing equipment is to be used. When conventional seeding is to be used, seedbed preparation will be done as follows:
Broadcast plantings
1. Tillage at a minimum, shall adequately loosen the soil to a depth of 4 to 6 inches; alleviate compaction; incorporate lime and fertilizer; smooth and firm the soil; allow for the proper placement of seed, sprigs, or plants; and allow for the anchoring of straw or hay mulch if a disk is to be used.
2. Tillage may be done with any suitable equipment.
3. Tillage should be done on the contour where feasible.
4. On slopes too steep for the safe operation of tillage equipment, the soil surface shall be pitted or trenched across the slope with appropriate hand tools to provide two places 6 to 8 inches apart in which seed may lodge and germinate. Hydraulic seeding may also be used.
Individual Plants
1. Where individual plants are to be set, the soil shall be prepared by excavating holes, opening furrows, or dibble planting.
2. For nursery stock plants, holes shall be large enough to accommodate roots without crowding.
3. Where pine seedlings are to be planted, subsoil under the row 36 inches deep on the contour four to six months prior to planting. Subsoiling should be done when the soil is dry, preferably in August or September.
6-43

Innoculants
All legume seed shall be inoculated with appropriate nitrogen-fixing bacteria. The innoculant shall be a pure culture prepared specifically for the seed species and used within the dates on the container.
A mixing medium recommended by the manufacturer shall be used to bond the innoculant to the seed. For conventional seeding, use twice the amount of innoculant recommended by the manufacturer. For hydraulic seeding, four times the amount of innoculant recommended by the manufacturer shall be used.
All inoculated seed shall be protected from the sun and high temperatures and shall be planted the same day inoculated. No inoculated seed shall remain in the hydroseeder longer than one hour.
Planting
Hydraulic Seeding
Mix the seed (innoculated if needed), fertilizer, and wood cellulose or wood pulp fiber mulch with water and apply in a slurry uniformly over the area to be treated. Apply within one hour after the mixture is made.
Conventional Seeding
Seeding will be done on a freshly prepared and firmed seedbed. For broadcast planting, use a culti-packerseeder, drill, rotary seeder, other mechanical seeder, or hand seeding to distribute the seed uniformly over the area to be treated. Cover the seed lightly with 1/8 to 1/4 inch of soil for small seed and 1/2 to 1 inch for large seed when using a cultipacker or other suitable equipment.
No-Till Seeding
No-till seeding is permissible into annual cover crops when planting is done following maturity of the cover crop or if the temporary cover stand is sparse enough to allow adequate growth of the permanent (perennial) species. No-till seeding shall be done with appropriate no-till seeding equipment. The seed must be uniformly distributed and planted at the proper depth.
Individual Plants
Shrubs, vines and sprigs may be planted with appropriate planters or hand tools. Pine trees shall be planted manually in the subsoil furrow. Each plant shall be set in a manner that will avoid crowding the roots.
Nursery stock plants shall be planted at the same depth or slightly deeper than they grew at the nursery.

The tips of vines and sprigs must be at or slightly above the ground surface.
Where individual holes are dug, fertilizer shall be placed in the bottom of the hole, two inches of soil shall be added and the plant shall be set in the hole.
Mulching
Mulch is required for all permanent vegetation applications. Mulch applied to seeded areas shall achieve 75% soil cover. Select the mulching material from the following and apply as indicated:
1. Dry straw or dry hay of good quality and free of weed seeds can be used. Dry straw shall be applied at the rate of 2 tons per acre. Dry hay shall be applied at a rate of 2 1/2 tons per acre.
2. Wood cellulose mulch or wood pulp fiber shall be used with hydraulic seeding. It shall be applied at the rate of 500 pounds per acre. Dry straw or dry hay shall be applied (at the rate indicated above) after hydraulic seeding.
3. One thousand pounds of wood cellulose or wood pulp fiber, which includes a tackifier, shall be used with hydraulic seeding on slopes 3/4:1 or steeper.
4. Sericea lespedeza hay containing mature seed shall be applied at a rate of three tons per acre.
5. Pine straw or pine bark shall be applied at a thickness of 3 inches for bedding purposes. Other suitable materials in sufficient quantity may be used where ornamentals or other ground covers are planted. This is not appropriate for seeded areas.
6. When using temporary erosion control blankets or block sod, mulch is not required.
7. Bituminous treated roving may be applied on planted areas on slopes, in ditches or dry waterways to prevent erosion. Bituminous treated roving shall be applied within 24 hours after an area has been planted. Application rates and materials must meet Georgia Department of Transportation specifications.
Wood cellulose and wood pulp fibers shall not contain germination or growth inhibiting factors. They shall be evenly dispersed when agitated in water. The fibers shall contain a dye to allow visual metering and aid in uniform application during seeding.

6-44

GaSWCC (Amended - 2000)

Applying Mulch
Straw or hay mulch will be spread uniformly within 24 hours after seeding and/or planting. The mulch may be spread by blower-type spreading equipment, other spreading equipment or by hand. Mulch shall be applied to cover 75% of the soil surface.
Wood cellulose or wood fiber mulch shall be applied uniformly with hydraulic seeding equipment.
Anchoring Mulch
Anchor straw or hay mulch immediately after application by one of the following methods:
1. Emulsified asphalt can be (a) sprayed uniformly onto the mulch as it is ejected from the blower machine or (b) sprayed on the mulch immediately following mulch application when straw or hay is spread by methods other than special blower equipment.
The combination of asphalt emulsion and water shall consist of a homogeneous mixture satisfactory for spraying. The mixture shall consist of 100 gallons of grade SS-1h or CSS-1h emulsified asphalt and 100 gallons of water per ton of mulch.
Care shall be taken at all times to protect state waters, the public, adjacent property, pavements, curbs, sidewalks, and all other structures from asphalt discoloration.
2. Hay and straw mulch shall be pressed into the soil immediately after the mulch is spread. A special "packer disk"' or disk harrow with the disks set straight may be used. The disks may be smooth or serrated and should be 20 inches or more in diameter and 8 to 12 inches apart. The edges of the disks shall be dull enough to press the mulch into the ground without cutting it, leaving much of it in an erect position. Mulch shall not be plowed into the soil.
3. Synthetic tackifiers or binders approved by GDOT shall be applied in conjunction with or immediately after the mulch is spread. Synthetic tackifiers shall be mixed and applied according to manufacturer's specifications. Refer to Tb - Tackifiers and Binders.
4. Rye or wheat can be included with Fall and Winter plantings to stabilize the mulch. They shall be applied at a rate of one-quarter to onehalf bushel per acre.
GaSWCC (Amended - 2000)

5. Plastic mesh or netting with mesh no larger than one inch by one inch may be needed to anchor straw or hay mulch on unstable soils and concentrated flow areas. These materials shall be installed and anchored according to manufacturer's specifications.

Bedding Material

Mulch is used as a bedding material to conserve moisture and control weeds in nurseries, ornamental beds, around shrubs, and on bare areas on lawns.

Material Grain straw Grass Hay Pine needles Wood waste

Depth 4" to 6" 4" to 6" 3" to 5" 4" to 6"

Irrigation

Irrigation will be applied at a rate that will not cause runoff.

Topdressing

Topdressing will be applied on all temporary and permanent (perennial) species planted alone or in mixtures with other species. Recommended rates of application are listed in Table 6-5.1.

Second Year and Maintenance Fertilization

Second year fertilizer rates and maintenance fertilizer rates are listed in Table 6-5.1.

Lime Maintenance Application

Apply one ton of agricultural lime every 4 to 6 years or as indicated by soil tests. Soil tests can be conducted to determine more accurate requirements if desired.

Use and Management

Mow Sericea lespedeza only after frost to ensure that the seeds are mature. Mow between November and March.

Bermudagrass, Bahiagrass and Tall Fescue may be mowed as desired. Maintain at least 6 inches of top growth under any use and management. Moderate use of top growth is beneficial after establishment.

Exclude traffic until the plants are well established. Because of the quail nesting season, mowing should not take place between May and September.

6-45

TYPE OF SPECIES
1. Cool season grasses
2. Cool season grasses and legumes
3. Ground covers
4. Pine seedlings
5. Shrub Lespedeza
6. Temporary cover crops seeded alone
7. Warm season grasses
8. Warm season grasses and legumes

Table 6-5.1. Fertilizer Requirements

YEAR
First Second Maintenance
First Second Maintenance
First Second Maintenance
First

ANALYSIS OR EQUIVALENT
N-P-K
6-12-12 6-12-12 10-10-10
6-12-12 0-10-10 0-10-10
10-10-10 10-10-10 10-10-10
20-10-5

First Maintenance
First

0-10-10 0-10-10
10-10-10

RATE

N TOP DRESSING
RATE

1500 lbs./ac. 1000 lbs./ac. 400 lbs./ac.

50-100 lbs./ac. 1/2/ __ 30

1500 lbs./ac. 1000 lbs./ac. 400 lbs./ac.

0-50 lbs./ac. 1/ __ __

1300 lbs./ac. 3/

__

1300 lbs./ac. 3/

__

1100 lbs./ac.

__

one 21-gram pellet __ per seedling placed in the closing hole

700 lbs./ac.

__

700 lbs./ac. 4/

500 lbs./ac.

30 lbs./ac. 5/

First Second Maintenance
First Second Maintenance

6-12-12 6-12-12 10-10-10
6-12-12 0-10-10 0-10-10

1500 lbs./ac. 800 lbs./ac. 400 lbs./ac.
1500 lbs./ac. 1000 lbs./ac. 400 lbs./ac.

50-100 lbs./ac. 2/6/ 50-100 lbs./ac. 2/ 30 lbs./ac.
50 lbs./ac./6/

1/ Apply in spring following seeding. 2/ Apply in split applications when high rates are used. 3/ Apply in 3 split applications. 4/ Apply when plants are pruned. 5/ Apply to grass species only. 6/ Apply when plants grow to a height of 2 to 4 inches.

6-46

GaSWCC (Amended - 2000)

6-47

GaSWCC (Amended - 2000)

Species
BAHIA, PENSACOLA (Paspalum notatum)
alone or with temporary cover
with other perennials
BAHIA, WILMINGTON (Paspalum notatum)
alone or with temporary cover
with other perennials
BERMUDA, COMMON (Cynodon dactylon) Hulled seed
alone with other perennials

Table 6-5.2 - Permanent Cover PLANTS, PLANTING RATES, AND PLANTING DATES FOR PERMANENT COVER

Broadcast

Rates 1/ - PLS 2/

Per

Per

Acre

1000

sq. ft.

60 lbs. 30 lbs.

1.4 lb. 0.7 lb.

60 lbs. 30 lbs.

1.4 lb. 0.7 lb.

10 lbs. 6 lbs.

0.2 lb. 0.1 lb.

Resource Area 3/

Planting Dates by Resource Areas Planting Dates
(Solid lines indicate optimum dates, dotted lines indicate permissible but marginal dates.)

J F M A M J J ASO N D

P

......................

.................................................

C

...............

.................................................

J F M A M J J ASO N D

M-L

..................

P

..............

................................................... ...................................................

Remarks
166,000 seed per pund. Low growing. Sod forming. Slow to establish. Plant with a companion crop. Will spread into bermuda pastures and lawns. Mix with Sericea lespedeza or weeping lovegrass.

Same as above.

J F M A M J J ASO N D

P

.......

.......

C

.........

.......

1,787,000 seed per pound. Quick cover. Low growing and sod forming. Full sun. Good for athletic fields.

6-48

Table 6-5.2 - Permanent Cover - continued PLANTS, PLANTING RATES, AND PLANTING DATES FOR PERMANENT COVER

Species
BERMUDA, COMMON (Cynodon dactylon)
Unhulled seed with temporary cover with other perennials BERMUDA SPRIGS (Cynodon dactylon) Coastal, Common, Midland, or Tift 44 Coastal, Common, or Tift 44
Tift 78
CENTIPEDE (Eremochloa ophiuroides)

Broadcast

Rates 1/ - PLS 2/

Per

Per

Acre

1000

sq. ft.

10 lbs. 6 lbs.

0.2 lb. 0.1 lb.

40 cu. ft.

0.9 cu. ft.

or

sod plugs 3' x 3'

Block sod only

Resource Area 3/
P C

Planting Dates by Resource Areas Planting Dates
(Solid lines indicate optimum dates, dotted lines indicate permissible but marginal dates.)
J F M A M J J ASO N D

Remarks

Plant with winter annuals.

J F M A M J J ASO N D

Plant with tall fescue.

M-L

........

.......

A cubic foot contains approximately 650 sprigs. A bushel contains 1.25 cubic feet or approximately 800 sprigs.

P

......

...............

Same as above.

C

......................

....................................................

C

......................

.................................................... Southern Coastal Plain only.

J F M A M J J ASO N D

P

Drought tolerant. Full sun or

C

partial shade. Effective adjacent

to concrete and in concentrated

flow areas. Irrigation is needed

until fully established. Do not

plant near pastures. Winterhardy

as far north as Athens and

Atlanta.

GaSWCC (Amended - 2000)

GaSWCC (Amended - 2000)

Table 6-5.2 - Permanent Cover - continued PLANTS, PLANTING RATES, AND PLANTING DATES FOR PERMANENT COVER

Species
CROWNVETECH (Coronilla varia)
with winter annuals or cool season grasses
FESCUE, TALL (Festuca arundinacea)
alone
with other perennials
KUDZU (Pueraria thumbergiana)
plants or crowns

Broadcast

Rates 1/ - PLS 2/

Per

Per

Acre

1000

sq. ft.

15 lbs.

0.3 lb.

50 lbs. 30 lbs.

1.1 lbs. 0.7 lb.

3' - 7' apart

Resource Area 3/

Planting Dates by Resource Areas Planting Dates
(Solid lines indicate optimum dates, dotted lines indicate permissible but marginal dates.)
J F M A M J J ASO N D

M-L

.....

P

.....

J F M A M J J ASO N D

Remarks
100,000 seed per pound. Dense growth. Drought tolerant and fire resistant. Attractive rose, pink, and white blossoms spring to late fall. Mix with 30 pounds of Tall fescue or 15 pounds of rye. Inoculate seed with M inoculant. Use from North Atlanta and Northward.

227,000 seed per pound. Use

alone only on better sites.

Not for droughty soils. Mix with

M-L

....

....

perennial lespedezas or

P

.... ....

crownvetch. Apply topdressing

in spring following fall

plantings. Not for heavy use

areas or athletic fields.

J F M A M J J ASO N D

ALL

....

Rapid and vigorous growth. Excellent in gully erosion control. Will climb. Good livestock forage.

6-49

6-50

Table 6-5.2 - Permanent Cover - continued PLANTS, PLANTING RATES, AND PLANTING DATES FOR PERMANENT COVER

Species
LESPEDEZA, SERICEA (Lespedeza cuneata)
scarified

Broadcast

Rates 1/ - PLS 2/

Per

Per

Acre

1000

sq. ft.

60 lbs.

1.4 lbs.

unscarified seed-bearing hay

75 lbs. 3 tons

1.7 lb. 138lb.

Resource Area 3/

Planting Dates by Resource Areas Planting Dates
(Solid lines indicate optimum dates, dotted lines indicate permissible but marginal dates.)
J F M A M J J ASO N D

Remarks

M-L

........

....

P

....

....

C

.......

............

M-L

..............................................

P

..............................................

C

..............................................

M-L

P

.......

C

......

350,000 seed per pound. Widely adapted. Low maintenance. Mix with weeping lovegrass, common bermuda, bahia, or tall fescue. Takes 2 to 3 years to become fully established. Excellent on roadbanks. Inoculate seed with EL inoculant.
Mix with Tall fescue or winter annuals.
Cut when seed is mature, but before it shatters. Add Tall fescue or winter annuals.

GaSWCC (Amended - 2000)

GaSWCC (Amended - 2000)

Table 6-5.2 - Permanent Cover - continued PLANTS, PLANTING RATES, AND PLANTING DATES FOR PERMANENT COVER

Species
LESPEDEZA Ambro virgata (Lespedeza virgata DC)
or Appalow (Lespedeza cuneata [Dumont] G. Don)
scarified
unscarified

Broadcast

Rates 1/ - PLS 2/

Per

Per

Acre

1000

sq. ft.

60 lbs. 75 lbs.

1.4 lb. 1.7 lb.

LESPEDEZA, SHRUB (Lespedeza bicolor) (Lespedeza thumbergii)
plants
LOVEGRASS, WEEPING (Eragrostis curvula)
alone
with other perennials

3' x 3'

4 lbs. 2 lbs.

0.1 lb. 0.05 lb.

Resource Area 3/

Planting Dates by Resource Areas Planting Dates
(Solid lines indicate optimum dates, dotted lines indicate permissible but marginal dates.)
J F M A M J J ASO N D

Remarks

300,000 seed per pound.

Height of growth is 18 to 24

inches. Advantageous in urban

areas. Spreading-type growth

has bronze coloration. Mix with

Weeping lovegrass, Common

bermuda, bahia, tall fescue or

M-L

........

.......

winter annuals. Do not mix with

P

.........

.......

Sericea lespedaza. Slow to

C

.......

........

develop solid stands. Inoculate

seed with EL inoculate.

M-L

.................................................

P

.................................................

C

.................................................

J F M A M J J ASO N D

M-L

P

C

Provide wildlife food and cover.

J F M A M J J ASO N D

M-L

........

.......

P

........

.......

C

........

.......

1,500,000 seed per pound. Quick cover. Drought tolerant. Grows well with Sericea lespedeza on roadbanks.

6-51

6-52

Table 6-5.2 - Permanent Cover - continued PLANTS, PLANTING RATES, AND PLANTING DATES FOR PERMANENT COVER

Species
MAIDENCANE (Panicum hemitomon)
sprigs PANICGRASS, ATLANTIC COASTAL (Panicum amarum var. amarulum)
REED CANARY GRASS (Phalaris arundinacea)

Broadcast

Rates 1/ - PLS 2/

Per

Per

Acre

1000

sq. ft.

2' x 3' spacing

20 lbs.

0.5 lb.

Resource Area 3/

Planting Dates by Resource Areas Planting Dates
(Solid lines indicate optimum dates, dotted lines indicate permissible but marginal dates.)
J F M A M J J ASO N D

ALL

.......

.......

J F M A M J J ASO N D

P

.......

C

.......

J F M A M J J ASO N D

Remarks
For very wet sites. May clog channels. Dig sprigs from local sources. Use along river banks and shorelines.
Grows well on coastal sand dunes, borrow areas, and gravel pits. Provides winter cover for wildlife. Mix with Sericea lespedeza except on sand dunes.

alone
with other perennials
SUNFLOWER, `AZTEC' MAXIMILLIAM (Helianthus maximiliani)

50 lbs. 30 lbs. 10 lbs.

1.1 lb. 0.7 lb. 0.2 lb.

M-L

...... .......

P

...... ...............

J F M A M J J ASO N D

M-L

........

P

........

C

1/ Reduce seeding rates by 50% when drilled. 2/ PLS is an abbreviation for Pure Live Seed. Refer to Section V.E. of these specifications. 3/ M-L represents to Mountain; Blue Ridge; and Ridges and Valleys MLRAs.
P represents the Southern Piedmont MLRA. C represents the Southern Coastal Plain; Sand Hills; Black Lands; and Atlantic Coast Flatwoods MLRAs. See Figure 6-4.1.

Grows similar to tall fescue.
227,000 seed per pound. Mix with weeping lovegrass or other low-growing grasses or legumes.

GaSWCC (Amended - 2000)

Table 6-5.3. Durable Shrubs and Ground Covers for Permanent Cover
Ground covers include a wide range of low-growing plants planted together in considerable numbers to cover large areas of the landscape. Ground covers grow slower than grasses. Weeds are likely to compete, especially the first year. Maintenance is needed to insure survival. These ground covers will not be used unless proper maintenance is planned. Maintain mulch at three-inch thickness until plants provide adequate cover.
Fall planting is encouraged because the need for constant watering is reduced and plants have time to establish new roots before hot weather.

Common Name
Albelia

Scientific Name
Abelia grandiflora

Carolina Yellow Jessamine

Gelsemium sempervirens

Carpet Blue

Ajuga reptans

Bearberry Cotoneaster
Ground Cover Cotoneaster
Rock Cotoneaster
Virginia Creeper
Daylily
English Ivy Compacta Holly Chinese Holly
Dwarf Burford Holly
Dwarf Yaupon Holly

Cotoneaster dammeri
Cotoneaster salicifoluis `Repens'
Cotoneaster horizontalis
Parthenocissue quinquefolia
Hemerocallis spp.
Hedera helix
Ilex crenata `Compacta'
Ilex cornuta `Rotunda'
Ilex burfordii `Nana'
Ilex vomitoria `Nana'

Mature Height 3-4 ft.
low
2-4 in.
2-4 ft. 1-2 ft. 1-2 ft. low 2-3 ft. low 3-4 ft. 3-4 ft. 5-8 ft. 3-4 ft.

Plant Spacing
5 ft.

Comments
Also a prostrate form 2 feet high. Sun, semi-shade. Semievergreen.

3 ft.

Vine.Yellow, trumpet-

like flowers. Hardy, one

of best vines. Ever-

green.

Native to Georgia.

3 ft.

Needs good drainage,

partial shade.

Blue or white flowers.

Evergreen.

5 ft.

White flowers, red

fruit. Sun. Evergreen.

5 ft.

White flowers, red

fruit. Sun. Evergreen.

5 ft.

Semi-evergreen.

Sun.

3 ft.

Red in fall. Vine.

Deciduous. Native to

Georgia.

2 ft.

Many flower colors.

Full sun. Very hardy.

3 ft.

Shade only. Climbs.

5 ft.

Sun, semi-shade.

5 ft.

Very durable. Sun,

semi-shade.

8 ft.

5 ft.

Very durable, sun,

semi-shade.

GaSWCC (Amended - 2000)

6-53

Table 6-5.3. Durable Shrubs and Ground Covers for Permanent Cover

Common Name
Repandens Holly Andorra Juniper
Andorra Compacta Juniper
Blue Chip Juniper
Blue Rug Juniper
Parsons Juniper
Pfitzer Juniper
Prince of Wales Juniper
Sargent Juniper
Shore Juniper

Scientific Name
Ilex crenata `Repandens'
Juniperus horizontalis `Plumosa'
Juniperus horizontalis `Plumosa compacta'
Juniperus horizontalis `Blue Chip'
Juniperus horizontalis `Wiltonii'
Juniperus davurica `Expansa' (Squamata Parsoni)
Juniperus chinensis `Pfitzerana'
Juniperus horizontalis `Prince of Wales'
Juniperus chinensis `Sargentii'
Juniperus conferta

Liriope
Creeping Liriope
Big Leaf Periwinkle
Common Periwinkle
6-54

Liriope muscari Liriope spicata Vinca major Vinca minor

Mature Height
2-3 ft.

Plant Spacing
5 ft.

Comments Sun, semi-shade.

2-3 ft.

5 ft.

Excellent for slopes.

Sun.

1-2 ft.

5 ft.

More compact than

andora.

8-10 in.

4 ft.

4-6 in.

3 ft.

Very low. Sun.

18-24 in.

5 ft.

One of the best, good winter cover.

6-8 ft.

6 ft.

Needs room.

8-10 in.

4 ft.

Feathery appearance.

1-2 ft.

5 ft.

2-3 ft.

5 ft.

8-10 in.

3 ft.

10-12 in.

1 ft.

Full sun. Needs good drainage. Good winter color.
Emerald Sea or Blue Pacific cultivars are good.
Spreads by runners.

12-15 in.

4 ft.

5-6 in.

4 ft.

Lilac flowers in spring. Semi-shade.
Lavender-blue flowers in spring. Semi-shade

GaSWCC (Amended - 2000)

Table 6-5.3. Durable Shrubs and Ground Covers for Permanent Cover

Common Name
Cherokee Rose
Memoria Rose
St. Johnswort
Anthony Waterer Spirea
Thunberg Spirea

Scientific Name
Rosa laevigata

Mature Height
2 ft.

Rosa weuchuriana Hypericum calycenum Spirea bumalda

2 ft. 8-12 in. 3-4 ft.

Spirea thinbergii

3-4 ft.

Plant Spacing
5 ft.

Comments
Rampant grower. Not for restricted spaces. State flower.

5 ft.

Rampant grower.

3 ft.

Semi-shade.

5 ft.

Sun.

5 ft.

Sun.

GaSWCC (Amended - 2000)

6-55

SITE
Borrow areas, graded areas, and spoil material

SOIL MATERIAL
Sandy

Loamy

Clay

Streambanks

Table 6-5.4. Trees for Erosion Control

COMMON SOILS
Lakeland, Troup

PLANTING TREE SPECIES 1/
Loblolly pine (Pinus taeda)

SPACING 2/

Orangeburg, Tifton
Cecil, Faceville

Longleaf pine (Pinus palustris)
Loblolly pine
Slash pine
Loblolly pine
Slash pine
Virginia pine (Pinus virginiana)
Willows 4/ (Salix species)

2/ 2/
2 ft x 2 ft

PLANTING DATES 3/

M-L,P 12/1-3/15

C

12/1-3/1

M-L,P 12/1-3/15

C

12/1-3/1

M-L,P 12/1-3/15

C

12/1-3/1

ALL 11/15-3/15

1/Other trees and shrubs listed on Table 6-5.3 may be interplanted with the pines for improved wildlife benefits.

2/Type of Planting

Tree Spacing

No. of Trees Per Acre

Trees alone

4 ft. x 4 ft.

2722

Trees in combination with grasses and/ or other plants

6 ft. x 6 ft.

1210

3/M-L represents the Mountains; Blue Ridge; and Ridges and Vallevs MLRAs

P represents the Southern Piedmont MLRA

C represents the Southern Coastal Plain; Sand Hills; Black Lands; and Atlantic Coast Flatwoods MLRAs (See Figure 6-4.1).

4/Fertilization of companion crop is ample for this species.

6-56

GaSWCC (Amended - 2000)

DISTURBED AREA

STABILIZATION

(WITH SODDING)

Ds4

DEFINITION
A permanent vegetative cover using sods on highly erodible or critically eroded lands.
PURPOSE
- Establish immediate ground cover. - Reduce runoff and erosion. - Improve aesthetics and land value. - Reduce dust and sediments. - Stabilize waterways, critical areas. - Filter sediments, nutrients and bugs. - Reduce downstream complaints. - Reduce likelihood of legal action. - Reduce likelihood of work stoppage due to legal action. - Increase "good neighbor" benefits.
CONDITIONS
This application is appropriate for areas which require immediate vegetative covers, drop inlets, grass swales, and waterways with intermittent flow.

PLANNING CONSIDERATIONS
Sodding can initially be more costly than seeding, but the advantages justify the increased initial costs.
1. Immediate erosion control, green surface, and quick use.
2. Reduced failure as compared to seed as well as the lack of weeds.
3. Can be established nearly year-round.
Sodding is preferable to seed in waterways and swales because of the immediate protection of the channel after application. Sodding must be staked in concentrated flow areas (See Figure 6-6.1).
Consider using sod framed around drop inlets to reduce sediments and maintaining the grade.
CONSTRUCTION SPECIFICATIONS INSTALLATION
Soil Preparation
Bring soil surface to final grade. Clear surface of trash, woody debris, stones and clods larger than 1". Apply sod to soil surfaces only and not frozen surfaces, or gravel type soils.
Topsoil properly applied will help guarantee a stand. Don't use topsoil recently treated with herbicides or soil sterilants.
Mix fertilizer into soil surface. Fertilize based on soil tests or Table 6-6.1.
Table 6-6.1. Fertilizer Requirements for Soil Surface Application

Fertilizer Type
10-10-10

Fertilizer Rate
(lbs /acre)
1000

Fertilizer Rate
(lbs /sq ft)
.025

Season Fall

Agricultural lime should be applied based on soil tests or at a rate of 1 to 2 tons per acre.

Installation

Lay sod with tight joints and in straight lines. Don't overlap joints. Stagger joints and do not stretch sod (See Figure 6-6.2)

GaSWCC (Amended - 2000)

6-57

On slopes steeper than 3:1, sod should be anchored with pins or other approved methods. Installed sod should be rolled or tamped to provide good contact between sod and soil.
Irrigate sod and soil to a depth of 4" immediately after installation.
Sod should not be cut or spread in extremely wet or dry weather. Irrigation should be used to supplement rainfall for a minimum of 2-3 weeks.
MATERIALS
Sod selected should be certified. Sod grown in the general area of the project is desirable.
1. Sod should be machine cut and contain 3/4" (+ or -1/4") of soil, not including shoots or thatch.
2. Sod should be cut to the desired size within + or -5%. Torn or uneven pads should be rejected.
3. Sod should be cut and installed within 36 hours of digging.
4. Avoid planting when subject to frost heave or hot weather if irrigation is not available.
5. The sod type should be shown on the plans or installed according to Table 6-6.2. See Figure 6-4.1 for your Resource Area.
Table 6-6.2. Sod Planting Requirements

Grass

Varieties

Bermudagrass

Common Tifway Tifgreen Tiflawn

Bahiagrass Pensacola

Centipede

-

St. Augustine Zoysia
Tall Fescue

Common Bitterblue Raleigh
Emerald Myer
Kentucky

Resource Area
M-L,P,C P,C P,C P,C P,C
P,C
C

Growing Season
Warm Weather
Warm Weather
Warm Weather
Warm Weather

P,C M-L,P

Warm Weather
Cool Weather

MAINTENANCE
Re-sod areas where an adequate stand of sod is not obtained. New sod should be mowed sparingly. Grass height should not be cut less than 2"-3" or as specified (See Figure 6-6.2).
Apply one ton of agricultural lime as indicated by soil test or every 4-6 years. Fertilize grasses in accordance with soil tests or Table 6-6.3.
Table 6-6.3. Fertilizer Requirements for Sod

Types of
Species

Planting Year

Fertilizer (N-P-K)

Cool

First

6-12-12

season Second 6-12-12

grasses Maintenance 10-10-10

Warm

First

6-12-12

season Second 6-12-12

grasses Maintenance 10-10-10

Rate Nitrogen Top (lbs./acre) Dressing Rate
(lbs./acre)

1500 1000 400

50-100 30

1500 800 400

50-100 50-100
30

6-58

GaSWCC (Amended - 2000)

SODDED WATERWAYS
FLOW
LAY SOD ACROSS THE DIRECTION OF FLOW.

USE PEGS OR STAPLES TO FASTEN SOD FIRMLY - AT THE ENDS OF STRIPS AND IN THE CENTER, OR EVERY 3-4 FEET IF
THE STRIPS ARE LONG. WHEN READY TO MOW, DRIVE PEGS OR STAPLES FLUSH WITH THE GROUND.

6" - 10"
PEG OR STAPLE
IN CRITICAL AREAS, SECURE SOD WITH NETTING. USE STAPLES.

Source: Va. DSWC

Figure 6-6.1

GaSWCC (Amended - 2000)

6-59

SODDING

INCORRECT CORRECT

BUTTING - ANGLED ENDS CAUSED BY THE AUTO MATIC SOD CUTTER MUST BE MATCHED CORRECTLY.

LAY SOD IN A STAGGERED PATTERN. BUTT THE STRIPS TIGHTLY AGAINST EACH OTHER. DO NOT LEAVE SPACES AND DO NOT OVERLAP. A SHARPENED MASON'S TROWEL IS A HANDY TOOL FOR TUCKING DOWN THE ENDS AND TRIMMING PIECES.

ROLL SOD IMMEDIATELY TO ACHIEVE FIRM CONTACT WITH THE SOIL.

WATER TO A DEPTH OF 4" AS NEEDED. WATER WELL AS SOON AS THE SOD IS LAID.

MOW WHEN THE SOD IS ESTABLISHED - IN 2-3 WEEKS. SET THE MOWER HIGH (2"-3").

APPEARANCE OF GOOD SOD

Source: Va. DSWC

SHOOTS OR GRASS BLADES. GRASS SHOULD BE GREEN AND HEALTHY, MOWED AT A 2"-3" CUTTING HEIGHT.
THATCH - GRASS CLIPPINGS AND DEAD LEAVES, UP TO 1/2" THICK. ROOT ZONE - SOIL AND ROOTS SHOULD BE 1/2" - 3/4" THICK, WITH DENSE ROOT MAT FOR STRENGTH.
Figure 6-6.2

6-60

GaSWCC (Amended - 2000)

Dust Control on

Disturbed Areas

Du

DEFINITION
Controlling surface and air movement of dust on construction sites, roads, and demolition sites.
PURPOSE
- To prevent surface and air movement of dust from exposed soil surfaces.
- To reduce the presence of airborne substances which may be harmful or injurious to human health, welfare, or safety, or to animals or plant life.
CONDITIONS
This practice is applicable to areas subject to surface and air movement of dust where on and off-site damage may occur without treatment.
METHOD AND MATERIALS
A. TEMPORARY METHODS
Mulches. See standard Ds1 - Disturbed Area Stabilization (With Mulching Only). Synthetic resins may be used instead of asphalt to bind mulch material. Refer to standard Tb-Tackifiers and Binders. Resins such as Curasol or Terratack should be used according to manufacturer's recommendations.
Vegetative Cover. See standard Ds2 - Disturbed Area Stabilization (With Temporary Seeding).
Spray-on Adhesives. These are used on mineral soils (not effective on muck soils). Keep traffic off these areas. Refer to standard Tb-Tackifiers and Binders.

Tillage. This practice is designed to roughen and bring clods to the surface. It is an emergency measure which should be used before wind erosion starts. Begin plowing on windward side of site. Chisel-type plows spaced about 12 inches apart, spring-toothed harrows, and similar plows are examples of equipment which may produce the desired effect.
Irrigation. This is generally done as an emergency treatment. Site is sprinkled with water until the surface is wet. Repeat as needed.
Barriers. Solid board fences, snowfences, burlap fences, crate walls, bales of hay and similar material can be used to control air currents and soil blowing. Barriers placed at right angles to prevailing currents at intervals of about 15 times their height are effective in controlling wind erosion.
Calcium Chloride. Apply at rate that will keep surface moist. May need retreatment.
B. PERMANENT METHODS
Permanent Vegetation. See standard Ds3 -Disturbed Area Stabilization (With Permanent Vegetation). Existing trees and large shrubs may afford valuable protection if left in place.
Topsoiling. This entails covering the surface with less erosive soil material. See standard Tp - Topsoiling.
Stone. Cover surface with crushed stone or coarse gravel. See standard Cr-Construction Road Stabilization.

GaSWCC (Amended - 2000)

6-61

6-62

GaSWCC (Amended - 2000)

Erosion Control Matting and

Blankets

Mb

DEFINITION
A protective covering (blanket) or soil stabilization mat used to establish permanent vegetation on steep slopes, channels, or shorelines.
PURPOSE
- To provide a microclimate which protects young vegetation and promotes its establishment.
- To reinforce the turf to resist forces of erosion during storm events.
CONDITIONS
Matting and blankets can be applied on steep slopes where erosion hazard is high and planting is likely to be too slow in providing adequate protective cover. Concentrated flow areas, all slopes steeper than 2.5:1 and with a height of ten feet or greater, and cuts and fills within stream buffers, shall be stabilized with the appropriate erosion control matting or blankets. Maintenance of final vegetative cover must be considered when choosing blankets verses matting.
On streambanks or tidal shorelines where moving water is present, matting can prevent new plantings from being washed away.
PLANNING CONSIDERATIONS
Care must be taken to choose the type of blanket or matting which is most appropriate for the specific needs of a project. Two general types of blankets and mats are discussed within this specification. Due to the abundance of erosion control matting and blanket products available, all of the advantages, disadvantages, and
GaSWCC (Amended - 2000)

specifications of all manufactured products will not be discussed in this manual. Manufacturer's instructions and recommendations, as well as a site visit by designer and plan reviewer is highly recommended to determine a product's appropriateness.
Temporary Erosion Control Blankets
This includes temporary "combination" blankets (rolled erosion control blankets-RECB) consisting of a plastic netting which covers and is intertwined with a natural organic or manmade mulch; or, a jute mesh which is typically homogeneous in design and can act alone as a soil stabilization blanket.
Temporary blankets as a minimum shall be used to stabilize concentrated flow areas with a velocity less than 5 ft/sec and slopes 2.5:1 or steeper with a height of 10 feet or greater. Because temporary blankets will deteriorate in a short period of time, they provide no enduring reduction in erosion protection.
Benefits of using erosion control blankets include the following:
1. Protection of the seed and soil from raindrop impact and subsequent displacement.
2. Thermal consistency and moisture retention for seedbed area.
3. Stronger and faster germination of grasses and legumes.
4. Planing off excess stormwater runoff.
5. Prevention of sloughing of topsoil added to steeper slopes.
Permanent Erosion Control Matting
Consists of a permanent non-degradable, three-dimensional plastic structure which can be filled with soil prior to planting. These mats are also known as permanent soil reinforcing mats (turf reinforcement matting). Roots penetrate and become entangled in the matrix, forming a continuous anchorage for surface growth and promoting enhanced energy dissipation. Matting shall be used when a vegetative lining is desired in stormwater conveyance channels where the velocity is between five and ten feet per second.
Benefits of using erosion control matting include the following:
1. All benefits gained from using erosion control blankets.
6-63

2. Causes soil to drop out of stormwater and fill matrix with fine soils which become the growth medium for the development of roots.
3. Acts with the vegetative root system to form an erosion resistant cover which resists hydraulic lift and shear forces when embedded in the soil within stormwater channels.
Materials
All blanket and matting materials shall be on the Georgia Department of Transportation Qualified Products List (QPL # 62 for blankets, QPL # 49 for matting).
All blankets shall be nontoxic to vegetation and to the germination of seed and shall not be injurious to the unprotected skin of humans. At a minimum, the plastic netting shall be intertwined with the mulching material/ fiber to maximize strength and provide for ease of handling.
Temporary Blankets
Machine produced temporary combination blankets shall have a consistent thickness with the organic material evenly distributed over the entire blanket area. All combination blankets shall have a minimum width of 48 inches. Machine produced combination blankets include the following:
a. Straw blankets are combination blankets that consist of weed-free straw from agricultural crops formed into a blanket. Blankets with a top side of photodegradable plastic mesh with a maximum mesh size of 5/16 x 5/16 inch and sewn to the straw with biodegradable thread is appropriate for slopes. The blanket shall have a minimum thickness of 3/8 inch and minimum dry weight of 0.5 pounds per square yard.
b. Excelsior blankets are combination blankets that consist of curled wood excelsior (80% of fibers are six inches or longer) formed into a blanket. The blanket shall have clear markings indicating the top side of the blanket and be smolder resistant. Blankets shall have photodegradable plastic mesh having a maximum mesh size of 1 1/2x3 inches. The blanket shall have a minimum thickness of 1/4 of an inch and a minimum dry weight of 0.8 pounds per square yard. Slopes require excelsior matting with the top side of the blanket covered in the plastic mesh, and for waterways, both sides of the blanket require plastic mesh.
c. Coconut fiber blankets are combination blankets that consist of 100% coconut fiber formed into a blanket. The minimum thickness of the blanket shall be 1/4 of an inch with a minimum dry weight of 0.5 pounds per square yard. Blankets shall have photodegradable plastic mesh,
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with a maximum mesh size of 5/8 x 5/8 inch and sewn to the fiber with a breakdown resistant synthetic yarn. Plastic mesh is required on both sides of the blanket if used in waterways. A maximum of two inches is allowable for the stitch pattern and row spacing.

d. Wood fiber blankets are combination blankets that consist of reprocessed wood fibers that do not possess or contain any growth or germination inhibiting factors. The blanket shall have a photodegradable plastic mesh, with a maximum mesh size of 5/8 x 3/4 inch, securely bonded to the top of the mat. The blanket shall have a minimum dry weight of 0.35 pounds per square yard. A maximum of two inches is allowable for the stitch pattern and row spacing. This practice shall be applied only to slopes.

e. Jute Mesh can be applied to slopes. Jute mesh with a 48 inch width shall show between 76 and 80 warpings and a one yard length shall show between 39 to 43 weftings. The woven mesh shall be at least 45 inches wide.Yarn shall have a unit weight of at least 0.9 pounds per square yard, but not more than 1.5 pounds per square yard.

Permanent Matting

Permanent matting shall consist of a lofty web of mechanically or melt bonded polymer nettings, monofilaments or fibers which are entangled to form a strong and dimensionally stable matrix. Polymer welding, thermal or polymer fusion, or the placement of fibers between two high strength, biaxially oriented nets bound securely together by parallel lock stitching with polyolefin, nylon or polyester threads are all appropriate bonding methods. Mats shall maintain their shape before, during, and after installation, under dry or water saturated conditions. Mats must be stabilized against ultraviolet degradation and shall be inert to chemicals normally encountered in a natural soil environment.

The mat shall conform to the following physical properties:

Property

Minimum Value

Thickness

0.5 inch

Weight

0.6 PSY

Roll Width

38 inches

Tensile Strength

Length (50% elongation)

15 lbs./in.

Length (ultimate)

20 lbs./in.

Width (50% elongation)

5 lbs./in.

Width (ultimate)

10 lbs./in.

(ASTM D 1682-6" strip)

Ultraviolet Stability

80%

(1000hrs. in an Atlas ARC Weatherometer, ASTM

G 23, Type D in accordance with ASTM D 822)

GaSWCC (Amended - 2000)

Site Preparation
After the site has been shaped and graded to the approved design, prepare a friable seedbed relatively free from clods and rocks more than one inch in diameter, and any foreign material that will prevent contact of the soil stabilization mat with the soil surface. Surface must be smooth to ensure proper contact of blankets or matting to the soil surface. If necessary, redirect any runoff from the ditch or slope during installation.
Staples
The following are considered appropriate stapling and staking materials.
Temporary Blankets
This includes straw, excelsior, coconut fiber, and wood fiber blankets. Staples shall be used to anchor temporary blankets. U-shaped wire (11 gauge or greater) staples with legs at least 6 inches in length and a crown of one inch or appropriate biodegradable staples can be used. Staples shall be of sufficient thickness for soil penetration without undue distortion.
Permanent Matting
Sound wood stakes, 1x3 inches stock sawn in a triangular shape, shall be used. Depending on the compaction of the soil, select stakes with a length from 12 to 18 inches. U-shaped staples shall be 11 gauge steel or greater, with legs at a minimum of 8 inches length with a 2 inch crown.
Planting
Lime, fertilizer, and seed shall be applied in accordance with seeding or other type of planting plan completed prior to installation of temporary combination blankets or jute mesh. For permanent mats, the area must be brought to final grade, plowed, limed, and fertilized. After the permanent mat has been installed and backfilled, the entire area shall be grassed. Refer to specification Ds3 - Disturbed Area Stabilization (With Permanent Vegetation).
Installation
See Figure 6-7.1 for typical installation guidelines. Follow manufacturer's recommendations for laying and stapling.

Maintenance
All erosion control blankets and matting should be inspected periodically following installation, particularly after rainstorms to check for erosion and undermining. Any dislocation or failure should be repaired immediately. If washouts or breakage occurs, reinstall the material after repairing damage to the slope or ditch. Continue to monitor these areas until they become permanently stabilized.

GaSWCC (Amended - 2000)

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Figure 6-7.1 - Typical Installation Guidelines for Matting and Blankets

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GaSWCC (Amended - 2000)

Polyacrylamide (PAM) Pm

DEFINITION
The land application of product containing anionic polyacrylamide (PAM) as temporary soil binding agents to reduce soil erosion.
PURPOSE
To reduce erosion from wind and water on construction sites and agricultural lands. Other benefits may include improved water quality, infiltration, soil fertility, and visibility.
CONDITIONS
This temporary practice is intended for direct soil surface application to sites where the timely establishment of vegetation may not be feasible or where vegetative cover is absent or inadequate. Such areas may include agricultural lands, where plant residues are inadequate to protect the soil surface, and construction sites where land-disturbing activities prevent the establishment or maintenance of a vegetative cover.
This temporary practice is not intended for application to surface waters of the state. It is intended for application within construction storm water ditches and storm drainages which feed into preconstructed sediment ponds or basins.
Federal, State and Local Laws
Anionic PAM application shall comply with all federal, state, and local laws rules or regulations governing anionic PAM. The operator is responsible for securing required permits. This standard does not contain the text of the federal, state, or local laws governing anionic PAM.
PLANNING CONSIDERATIONS
Anionic PAM is available in emulsions, powders, and gel bars or logs. It is required that other Best Management Practices be used in combination with anionic PAM.
The use of seed and mulch for additional erosion protection beyond the life of the anionic PAM is recommended. Repeat application if disturbance occurs to target area.
The following are additional recommendations relating to design which may enhance the use of or avoid problems with the practice:
1. Use setbacks when applying anionic PAM near natural waterbodies.
GaSWCC (Amended - 2000)

Figure 6-8.1. Hydroseeded Slope with and without Polyacrylamide Application
2. Consider that decreased performance can occur due to ultra-violet light and time after mixing when applying anionic PAM.
3. In flow concentration channels, the effectiveness of anionic PAM for stabilization decreases.
4. Mulch to protect seed, if seed is applied with anionic PAM.
5. Never add water to PAM, add PAM slowly to water. If water is added to PAM, "globs" can form which can clog dispensers. This signifies incomplete dissolving of the PAM and therefore increases the risk of under-application.
6. NOT ALL POLYMERS ARE PAM.
CRITERIA
Application rates shall conform to manufacturer's guidelines for application.
1. Only the anionic form of PAM shall be used. Cationic PAM is toxic and shall NOT be used.
2. PAM and PAM mixtures shall be environmentally benign, harmless to fish, wildlife, and plants. PAM and PAM mixtures shall be noncombustible.
3. Anionic PAM, in pure form, shall have less than or equal to 0.05% acrylamide monomer by weight, as established by the Food and Drug Administration and the Environmental Protection Agency.
4. To maintain less than or equal to 0.05% of acrylamide monomer, the maximum application rate of PAM, in pure form, shall not exceed 200 pounds/acre/year. Do not over apply PAM. Excessive application of PAM can lower infiltration rate or suspend solids in water, rather than promoting settling.
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5. Users of anionic PAM shall obtain and follow all Material Safety Data Sheet requirements and manufacturer's recommendations.
6. Additives such as fertilizers, solubility promoters or inhibitors, etc. to PAM shall be non-toxic.
7. The manufacturer or supplier shall provide written application methods for PAM and PAM mixtures. The application method shall insure uniform coverage to the target and avoid drift to non-target areas including waters of the state. The manufacturer or supplier shall also provide written instructions to insure proper safety, storage, and mixing of the product.
8. Gel bars or logs of anionic PAM mixtures may be used in ditch systems. This application shall meet the same testing requirement as anionic PAM emulsions and powders.
9. To prevent exceeding the acrylamide monomer limit in the event of a spill, the anionic PAM in pure form shall not exceed 200 pounds/batch at 0.05% acrylamide monomer (AMD) or 400 pounds/batch at 0.025% AMD.
OPERATION AND MAINTENANCE
Maintenance will consist of reapplying anionic PAM to disturbed areas including high use traffic areas which interfere in the performance of this practice.

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GaSWCC (Amended - 2000)

STREAMBANK

STABILIZATION

Sb

(USING PERMANENT VEGETATION)

Use jute mesh and other geotextiles to aid in soil stabilization and revegetation. Refer to Mb - Matting and Blankets.
Live Stake
Fresh, live woody plant cuttings are tamped into the ground as stakes, intended to root and grow into mature shrubs that will stabilize soils and restore the riparian zone habitats. Live stakes provide no immediate streambank stabilization. Willow species work best.

DEFINITION
The use of readily available native plant materials to maintain and enhance streambanks, or to prevent, or restore and repair small streambank erosion problems.
PURPOSE
- Lessen the impact of rain directly on the soil.
- Trap sediment from adjacent land.
- Form a root mat to stabilize and reinforce the soil on the streambank.
- Provide wildlife habitat.
- Enhance the appearance of the stream.
- Lower summertime water temperatures for a healthy aquatic population.
NOTE: Careful thought, planning and execution is required to assure that the streambank stabilization project is done efficiently and correctly. Please refer to SSWCC's Guidelines for Streambank Restoration and Chapters 16 and 18 of the NRCS Engineering Field Handbook for more detailed information.
SELECTED MEASURES
Revegetation includes seeding and sodding of grasses, seeding in combination with erosion control fabrics, and the planting of woody vegetation (shrubs and trees). Refer to Ds3 - Disturbed Area Stabilization (With Permanent Vegetation), Ds4 - Disturbed Area Stabilization (With Sodding), and Bf - Buffer Zone.
GaSWCC (Amended - 2000)

LIVE CUTTINGS

Note: Rooted/leafed condition of the living plant material is not representative at the time of installation.
Robbin B. Sotir & Associates

Figure 6-9.1 - Illustration of a Live Stake

Joint Planting
Install live willow stakes between rock previously placed along the streambank. Rock needs to be loosely dumped or hand placed and no thicker than 2 feet. Joint plantings enable a bank previously installed with conventional rip-rap to become naturalized.

LIVE STAKE RIPRAP

Note: Rooted/leafed condition of the living plant material is not representative at the time of installation.
Robbin B. Sotir & Associates
Figure 6-9.2 - Illustration of Joint Planting
Live Fascine
Live fascines are sausage-like bundles of live cut branches placed into trenches along the streambank. They provide immediate protection from erosion when properly used and installed. Willow species work best.
Live fascines create very little site disturbance as compared to other systems and works especially well when combined with surface covers such as jute mesh or coir fabrics.
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LIVE BRANCHES DEAD STOUT STAKE
LIVE STAKE
TWINE LIVE BRANCHES

Note: Rooted/leafed condition of the living plant material is not representative at the time of installation.

Robbin B. Sotir & Associates

Figure 6-9.3 - Illustration of a Live Fascine

Brushmattress

A combination of living units that forms an immediate protective surface cover over the streambank. Living units used include live stakes, live fascines, and a mattress branch cover (long, flexible branches placed against the bank surface).

Brushmattreses require a great deal of live material, and is complicated as well as expensive to evaluate, design, and install.

Brushmattesses capture sediment during flood conditions, produces habitat rapidly and quickly develops a healthy riparian zone.

LIVE STAKE LIVE BRANCHES DEAD STOUT STAKE
LIVE BRANCHES STAKE WIRE

Note: Rooted/leafed condition of the living plant material is not representative at the time of installation.
LIVE FASCINE

Robbin B. Sotir & Associates
Figure 6-9.4 - Illustration of a Brushmattress
Live Cribwall
A rectangular framework of logs or timbers, rock, and woody cuttings. This requires a great deal of assessment and understanding of stream behavior.
Cribwalls can be complicated and expensive if a supply of wood and some volunteer help is not available.

Benefits include developing a natural streambank or upland slope appearance after it has begun to grow and provides excellent habitat for a variety of fish, birds, and animals. It is very useful where space is limited on small, narrow stream corridors.
TIMBER/LOGS SELECT FILL MATERIAL

EXISTING

ROCK

LIVE BRANCHES 50/50 SELECT FILLROCK MIX
Robbin B. Sotir & Associates

Figure 6-9.5 - Illustration of a Live Cribwall

Branchpacking

Process of alternating layers of live branches and soil, incorporated into a hole, gully, or slumped-out area in a slope or streambank. There is a moderate to complex level of difficulty for construction.

Branchpacking produces an immediate filter barrier, reducing scouring conditions, repairing gully erosion, and providing habitat cover and bank reinforcement.

This is one of the most effective and inexpensive methods for repairing holes in earthen embankments along small stream sites.

Note: Rooted/leafed condition of the living plant material is not representative at the time of installation.

COMPACTED FILL WOODEN STAKES SELECTED ROOTED PLANTS OR CUTTINGS
Robbin B. Sotir & Associates

Figure 6-9.6 - Illustration of Branchpacking

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GaSWCC (Amended - 2000)

Table 6-9.1. Streambank Erosion Protection Measures Relative Costs and Complexity

Measure
Live Stake Joint planting Live Fascine Bushmattress

Relative Cost Low Low*
Moderate Moderate

Live cribwall Branchpacking

High Moderate

Conventional vegetation

Low to Moderate

Conventional bank armoring (riprap)

Moderate to High

*Assumes rock is in place.

Relative Complexity
Simple
Simple*
Moderate
Moderate to Complex
Complex
Moderate to Complex
Simple to Moderate
Moderate to Complex

MAINTENANCE
Check banks after every high-water event, fixing gaps in the vegetative cover at once with structural materials or new plants, and mulching if necessary. Fresh cuttings from other plants may be used for repairs.
When fertilizer is applied on the surface, it is best to apply about one-half at planting, one-fourth when new growth is about two inches tall, and one-fourth about six weeks later.
REFERENCES
Guidelines for Streambank Restoration. Georgia Soil and Water Conservation Commission
LOCAL CONTACTS
USDA Natural Resources Conservation Service
Georgia Soil and Water Conservation Commission

GaSWCC (Amended - 2000)

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6-72

GaSWCC (Amended - 2000)

Tackifiers and Binders Tb

DEFINITION

Substances used to anchor straw or hay mulch by causing the organic material to bind together.

PURPOSE

To prevent the movement of mulching material from the desired location. Increases performance of the mulching material, so that it can:

- Increase infiltration.

- Reduce wind and water erosion.

- Conserve moisture, prevent surface compaction or crusting.

- Control undesirable vegetation.

- Modify soil temperature.

- Increase biological activity in the soil.

CONDITIONS

All organic mulching materials shall be anchored by tackifiers/binders or matting/netting. Tackifiers and binders are used to anchor wood cellulose, wood pulp fiber, and other mulch materials applied with hydroseeding equipment.

APPROVED TACKIFIERS AND BINDERS

Product or Trade Name

Recommended Application Rate

A500 HYDRO-STIK Agro Tack MP CONWED CON-TAC EcoTak-OP/EcoTAk-SATII PMR Emulsified Asphalt
Hercules Soilloc-E HYDRO-BOND RMB-plus TACPAC GT TERRA-MULCH TACKING AGENT III

40 lb./ac. PMR 40 lb./ac.
100 gal. of SS-1h or CSS-1h and 100 gal. of water per ton of mulch PMR 35 lb./ac. 80-120 lb./ac. PMR
PMR

GaSWCC (Amended - 2000)

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GaSWCC (Amended - 2000)

SECTION III: STRUCTURAL PRACTICES

GaSWCC (Amended - 2000)

6-75

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GaSWCC (Amended - 2000)

Check Dam

Cd

DEFINITION
Small temporary barrier, grade control structure, or dam constructed across a swale, drainage ditch, or area of concentrated flow.
PURPOSE
To minimize the erosion rate by reducing the velocity of storm water in areas of concentrated flow.
CONDITIONS
This practice is applicable for use in small open channels and is not to be used in a live stream. Specific applications include:
1. Temporary or permanent swales or ditches in need of protection during establishment of grass linings.
2. Temporary or permanent swales or ditches which, due to their short length of service or other reasons, cannot receive a permanent non-erodible lining for an extended period of time.
3. Other locations where small localized erosion and resulting sedimentation problems exist.
DESIGN CRITERIA
Formal design is not required.The following standards shall be used:
Drainage Area
For stone check dams, the drainage area shall not exceed two acres. For haybales, the drainage area shall not exceed one acre.
GaSWCC (Amended - 2000)

Height
The center of the check dam must be at least 9 inches lower than outer edges. Dam height should be 2 feet maximum measured to center of check dam. (See Figure 6-10.2)
Side Slopes
Side slopes shall be 2:1 or flatter.
Spacing
Two or more check dams in series shall be used for drainage areas greater than one acre. Maximum spacing between dams should be such that the toe of the upstream dam is at the same elevation as the top of the downstream dam. (See Figure 6-10.1)
Geotextiles
A geotextile should be used as a separator between the graded stone and the soil base and abutments. The geotextile will prevent the migration of soil particles from the subgrade into the graded stone. The geotextile shall be selected/specified in accordance with AASHTO M288-96 Section 7.3, Separation Requirements, Table 3. Geotextiles shall be "set" into the subgrade soils. The geotextile shall be placed immediately adjacent to the subgrade without any voids and extend five feet beyond the downstream toe of the dam to prevent scour.
CONSTRUCTION SPECIFICATIONS
The following types of check dams are used for this standard:

Stone Check Dams

Cd-S

Stone check dams should be constructed of graded size 2-10 inch stone. (See Figure 6-10.2) Mechanical or hand placement shall be required to insure complete coverage of entire width of ditch or swale and that center of dam is lower than edges.

Haybale Check Dams Cd-Hb

Staked and embedded hay-bales may be used as temporary check dams in concentrated flow areas while vegetation is becoming established. They should not be used where the drainage area exceeds one acre. Haybales should be embedded a minimum of 4 inches. (See Figure 6-10.3)

6-77

MAINTENANCE
Periodic inspection and required maintenance must be provided. Sediment shall be removed when it reaches a depth of one-half the original dam height or before. If the area is to be mowed, check dams shall be removed once final stabilization has occurred. Otherwise, check dams may remain in place permanently. After removal, the area beneath the dam shall be seeded and mulched immediately.

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GaSWCC (Amended - 2000)

L = The distance such that points A and B are of equal elevation

A

L

B

SPACING BETWEEN CHECK DAMS

Figure 6-10.1

Geotextile

STONE CHECK DAM 9"

24" maximum

Geotextile Flow
GaSWCC (Amended - 2000)

2:1

24" maximum

Figure 6-10.2 6-79

A

A

B

Points A should be higher than point B
PROPER PLACEMENT OF STRAW BALE BARRIER IN DRAINAGE WAY

Binding Wire or Twine
Filtered Runoff

Staked and Entrenched Straw Bale
Compacted Soil to Prevent Piping
Sediment Laden Runoff

Note: Embed hay bales a minimum of 4 inches.
CROSS-SECTION OF A PROPERLY INSTALLED STRAW BALE

6-80

Figure 6-10.3

GaSWCC (Amended - 2000)

Channel Stabilization Ch
DEFINITION
Improving, constructing or stabilizing an open channel for water conveyance.
PURPOSE
Open channels are constructed or stabilized to be non-erosive, with no sediment deposition and to provide adequate capacity for flood water, drainage, other water management practices, or any combination thereof.
CONDITIONS
This standard applies to the improvement, construction or stabilization of open channels and existing ditches with drainage areas less than one square mile. This standard applies only to channels conveying intermittent flow, not to channels conveying a continuous, live stream.
An adequate outlet for the modified channel length must be available for discharge by gravity flow. Construction or other improvements of the channel should not adversely affect the environmental integrity of the area and must not cause significant erosion upstream or flooding and/or sediment deposition downstream.
DESIGN CRITERIA
Planning The alignment and design of channels shall give care-
ful consideration to the preservation of valuable fish and wildlife habitat and trees of significant value for wildlife food or shelter or for aesthetic purposes.

Where channel construction will adversely affect significant fish or wildlife habitat, mitigation measures should be included in the plan. Mitigation measures may include pools, riffles, flats, cascades or other similar provisions.
As many trees as possible are to be left inside channel rights-of-way considering the requirements of construction, operation, and maintenance.
Unusually large or attractive trees shall be preserved.
Realignment
The realignment of channels shall be kept to an absolute minimum and should be permitted only to correct an adverse environmental condition.
Channel Capacity
The capacity for open channels shall be determined by procedures applicable to the purposes to be served.
Hydraulic Requirements
Manning's formula shall be used to determine velocities in channels. The "n" values for use in this formula shall be estimated using currently accepted guides along with knowledge and experience regarding the conditions. Acceptable guides can be found in hydrology textbooks.
Channel Cross-Section
The required channel cross-section and grade are determined by the design capacity, the materials in which the channel is to be constructed, and the requirements for maintenance. A minimum depth may be required to provide adequate outlets for subsurface drains and tributary channels.
Channel Stability
All channel construction, improvement and modification shall be in accordance with a design expected to result in a stable channel which can be maintained.
Characteristics of a Stable Channel
1. Aggradation or degradation does not interfere with the function of the channel or affect adjacent areas.
2. The channel banks do not erode to the extent that the channel cross-section is changed appreciably.
3. Excessive sediment bars do not develop.

GaSWCC (Amended - 2000)

6-81

4. Excessive erosion does not occur around culverts, bridges or elsewhere.

5. Gullies do not form or enlarge due to the entry of uncontrolled surface flow to the channel.

6. The determination of channel stability considers "bankfull" flow. Bankfull flow is defined as flow in the channel which creates a water surface that is at or near normal ground elevation for a significant length of a channel reach. Excessive channel depth created by cutting through high ground should not be considered in determinations of bankfull flow.

CHANNEL LININGS AND STRUCTURAL MEASURES

Where channel velocities exceed safe velocities for vegetated lining due to increased grade or a change in channel cross-section, or where durability of vegetative lining is adversely affected by seasonal changes, channel linings of rock, concrete or other durable material may be needed. Grade stabilization structures may also be needed.

Channels may be stabilized by using one or more of the following methods:

Vegetated Lining

Ch-V

Vegetated lining shall be designed to resist erosion when the channel is flowing at the bankfull discharge or 25-year frequency discharge, whichever is the lesser. Temporary erosion control blankets or sod shall be used on all channels and concentrated flow areas to aid in the establishment of the vegetated lining. If a vegetated lining is desired in a channel with velocities between 510 ft/sec, permanent soil reinforcement matting shall be used. Refer to specifications Ds3 - Disturbed Area Stabilization (With Permanent Vegetation), Ds4 Disturbed Area Stabilization (With Sodding), and Mb - Matting and Blankets.

Rock Riprap Lining

Ch-Rp

Rock riprap shall be designed to resist displacement when the channel is flowing at the bankfull discharge or 25-year frequency discharge, whichever is the lesser. Rock riprap lining should be used when channel velocities are between 5 and 10 ft/sec.
Dumped and machine placed riprap should not be installed on slopes steeper than 1-1/2 horizontal to 1 vertical. Rock shall be dense, resistant to the action of air and water, and suitable in all other respects for the purpose intended. Rock shall be installed according to standards specified in Riprap, Appendix C.

6-82

A filter blanket layer consisting of an appropriately designed graded filter sand and/or gravel or geotextile material shall be placed between the riprap and base material. The gradation of the filter blanket material shall be designed to create a graded filter between the base material and the riprap. A geotextile can be used as a substitution for a layer of sand in a graded filter or as the filter blanket. Criteria for selecting an appropriate geotextile and guidance for recommended drop heights and stone weights are found in AASH-TO M288-96 Section 7.5, Permanent Erosion Control Specifications.

Concrete Lining

Ch-C

If a channel has velocities high enough to require a concrete lining (when channel velocities exceed 10 ft/sec), methods should be utilized to reduce the velocity of the runoff and reduce erosion at the outlet - a common problem created by the smooth, concrete lining. Refer to specification St - Storm Drain Outlet Protection for information regarding energy dissipators.

If a concrete lining is chosen, it shall be designed according to currently accepted guides for structural and hydraulic adequacy. It must be designed to carry the required discharge and to withstand the loading imposed by site conditions.

A separation geotextile should be placed under concrete linings to prevent undermining in the event of stress cracks due to settlement of the base material. The separation geotextile will keep the base material soils in place and minimize the likelihood of a system failure.

Grade Stabilization Structures

Grade stabilization structures are used to reduce or prevent excessive erosion by reduction of velocities in the watercourse or by providing structures that can withstand and reduce the higher velocities. They may be constructed of concrete, rock, masonry, steel, aluminum, or treated wood.

These structures are constructed where the capability of earth and vegetative measures is exceeded in the safe handling of water at permissible velocities, where excessive grades or overall conditions are encountered or where water is to be lowered structurally from one elevation to another. These structures should generally be planned and installed along with or as a part of other erosion control practices.

The structures shall be designed hydraulically to adequately carry the channel discharge and structurally to withstand loadings imposed by the site conditions. The structure shall meet requirements of Gr - Grade Stabilization Structure.

GaSWCC (Amended - 2000)

CONSTRUCTION SPECIFICATIONS
1. Where needed, all trees, brush, stumps and other objectionable materials shall be removed so they will not interfere with the construction or proper functioning of the channel.
2. Where possible, trees will be left standing, and stumps will not be removed.
3. Excavation shall be at the locations and grades shown on the drawings. The lining shall not compromise the capacity of the channel, e.g. the emergency spillway shall be over-excavated so that the lining will be flush with the slope surface.
4. The geotextile shall be placed on a smooth graded surface. The geotextile shall be placed in such a manner that it will not excessively stretch or tear upon placement of the overlying materials. Care should be taken to place the geotextile in intimate contact with the soil such that no void spaces exist between the underlying soil and the geotextile.
5. Construction plans will specifically detail the location and handling of spoils. Spoil material resulting from clearing, grubbing and channel excavation shall be disposed of in a manner which will:
a. not cause an increase in flood stage,
b. minimize overbank wash,
c. not cause an adverse effect on the environmental integrity of the area,
d. provide for the free flow of water between the channel and flood plain unless the valley routing and water surface profile are based on continuous dikes being installed,
e. leave the right-of-way in the best condition feasible, and

f. improve the aesthetic appearance of the site to the extent feasible.
6. Channel linings shall be established or installed immediately after construction or as soon as weather conditions permit.
7. Structures shall be installed according to lines and grades shown on the plan. The foundation for structures shall be cleared of all undesirable materials prior to the installation of the structures.
8. Materials used in construction shall be of permanency commensurate with the design frequency and life expectancy of the facility.
9. Earthfill, when used as a part of the structures, shall be placed according to the installation requirements for sediment basin embankments.
10. Construction operations shall be carried out in such a manner that erosion and air and water pollution will be minimized. State and local laws concerning pollution abatement shall be complied with.
11. Vegetation shall be established on all disturbed areas immediately after construction. If weather conditions cause a delay in establishing vegetation, the area shall be mulched in accordance with the standard for mulching. Refer to specification Ds1 - Disturbed Area Stabilization (With Mulching Only). Seeding, fertilizing and mulching shall conform to the standard for permanent vegetative cover. Refer to specification Ds3-Disturbed Area Stabilization (With Permanent Vegetation).
12. All temporary access roads or travelways shall be appropriately closed to exclude traffic.
13. Trees and other fallen natural vegetation not causing a deterrent to stream flow should be left for the purpose of habitat.

TO BE SHOWN ON THE EROSION AND SEDIMENT CONTROL PLAN
1. The velocity in the channel, in ft/sec, for when the channel is flowing at the bank-full discharge or 25-year frequency discharge, whichever is the lesser.
2. The type of lining to be used to stabilize the channel, i.e. vegetation (Ch-V: indicate type of vegetation and matting or blanket to be used), riprap (Ch-Rp: indicate average stone size), or concrete (Ch-C).

GaSWCC (Amended - 2000)

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GaSWCC (Amended - 2000)

Construction Exit

Co

DEFINITION
A stone stabilized pad located at any point where traffic will be leaving a construction site to a public rightof-way, street, alley, sidewalk or parking area or any other area where there is a transition from bare soil to a paved area.
PURPOSE
To reduce or eliminate the transport of mud from the construction area onto public rights-of-way by motor vehicles or by runoff.
CONDITIONS
This practice is applied at appropriate points of construction egress. Geotextile underliners are required to stabilize and support the pad aggregates.
DESIGN CRITERIA
Formal design is not required.The following standards shall be used:
Aggregate Size
Stone will be in accordance with National Stone Association R-2 (1.5 to 3.5 inch stone).
Pad Thickness
The gravel pad shall have a minimum thickness of 6 inches.
Pad Width
At a minimum, the width should equal full width of all points of vehicular egress, but not less than 20 feet wide.
GaSWCC (Amended - 2000)

Washing
If the action of the vehicle traveling over the gravel pad does not sufficiently remove the mud, the tires should be washed prior to entrance onto public rightsof-way. When washing is required, it shall be done on an area stabilized with crushed stone and provisions that intercept the sediment-laden runoff and direct it into an approved sediment trap or sediment basin.
Location
The exit shall be located or protected to prevent sediment from leaving the site.
CONSTRUCTION SPECIFICATIONS
It is recommended that the entrance area be excavated to a depth of 3 inches and be cleared of all vegetation and roots.
Diversion Ridge
On sites where the grade toward the paved area is greater than 2%, a diversion ridge 6 to 8 inches high with 3:1 side slopes shall be constructed across the foundation approximately 15 feet above the road.
Geotextile
The geotextile underliner must be placed the full length and width of the entrance. Geotextile selection shall be based on AASHTO M288-98 specification:
1. For subgrades with a CBR greater than or equal to 3 or shear strength greater than 90 kPa, geotextile must meet requirements of section AASHTO M288-96 Section 7.3, Separation Requirements.
2. For subgrades with a CBR between 1 and 3 or sheer strength between 30 and 90 kPa, geotextile must meet requirements of section AASHTO M288-96 Section 7.4, Stabilization Requirements.
MAINTENANCE
The exit shall be maintained in a condition which will prevent tracking or flow of mud onto public rights-ofway. This may require periodic top dressing with 1.5-3.5 inch stone, as conditions demand, and repair and/or cleanout of any structures to trap sediment. All materials spilled, dropped, washed, or tracked from vehicles or site onto roadways or into storm drains must be removed immediately.
6-85

Hard Surface Public Road
6" Minimum N.S.A. R-2 (1.5"-3.5")
Coarse Aggregate Geotextile Underliner

50" Minimum 20" Minimum

CRUSHED STONE CONSTRUCTION EXIT

6-86

Figure 6-11.1

GaSWCC (Amended - 2000)

Construction Road

Stabilization

Cr

DEFINITION
A travelway constructed as part of a construction plan including access roads, subdivision roads, parking areas, and other on-site vehicle transportation routes.
PURPOSE
To provide a fixed route for travel for construction traffic and reduce erosion and subsequent regrading of permanent roadbeds between time of initial grading and final stabilization.
CONDITIONS
This practice is applicable where travelways are needed in a planned land use area or wherever stonebase roads or parking areas are constructed, whether permanent or temporary, for use by construction traffic.
PLANNING CONSIDERATIONS
Areas graded for construction vehicle transport and parking purposes are especially susceptible to erosion. The exposed soil is continually disturbed, eliminating the possibility of stabilization with vegetation. The prolonged exposure of the roads and parking areas to surface runoff can create severe rilling and muddying of the areas, requiring regrading before paving. The soil removed during this process may enter streams and other waters of the state via stormwater management systems, compromising the water quality. Also, because the roads become so unstable during wet weather, they are virtually unusable, limiting access, and causing delays in construction.

DESIGN CRITERIA
TEMPORARY ROADS AND PARKING AREAS
The type of vehicle or equipment, speed, loads, climatic, and other conditions under which vehicles and equipment are expected to operate shall be considered.
Location
Temporary roads shall be located to serve the purpose intended, facilitate the control and disposal of water, control or reduce erosion, and make the best use of topographic features.
Temporary roads shall follow the contour of the natural terrain to minimize disturbance of drainage patterns. If a temporary road must cross a stream, the crossing must be designed, installed and maintained according to specification Sr - Temporary Stream Crossing.
Temporary parking areas should be located on naturally flat areas to minimize grading.
Grade and Alignment
The gradient and vertical and horizontal alignment shall be adapted to the intensity of use, mode of travel, and level of development.
Grades for temporary roads should not exceed ten percent except for very short lengths (200 feet or less), but maximum grades of 20 percent or more may be used if necessary for special uses. Frequent grade changes generally cause fewer erosion problems than long continuous gradients.
Curves and switchbacks must be of sufficient radius for trucks and other large vehicles to negotiate easily. On temporary roads, the radius should be no less than 35 feet for standard vehicles and 50 feet for tractor-trailers.
Grades for temporary parking areas should be sufficient to provide drainage but should not exceed four percent.
Width
Temporary roadbeds shall be at least 14 feet wide for one-way traffic and 20 feet wide for two-way traffic. The width for two-way traffic shall be increased approximately four feet for trailer traffic. A minimum shoulder width shall be two feet on each side. Where turnouts are used, road width shall be increased to a minimum of 20 feet for a distance of 30 feet.

GaSWCC (Amended - 2000)

6-87

Side Slopes
All cuts and fills shall have side slopes designed to be stable for the particular site conditions and soil materials involved. All cut and fills shall be 2:1 or flatter to the extent possible. When maintenance by machine mowing is planned, side slopes shall be no steeper than 3:1.
Drainage
The type of drainage structure used will depend on the type of enterprise and runoff conditions. The capacity and design shall be consistent with sound engineering principles and shall be adequate for the class of vehicle, type of road, development, or use. Structures should be designed to withstand flows from a 25-year, 24-hour frequency storm or the storm specified in Title 12-7-1 of the Official Code of Georgia Annotated. Channels shall be designed to be on stable grades or protected with structures or linings for stability.
Water breaks or bars may be used to control surface runoff on low-intensity use roads.
Stabilization
Geotextile should be applied to the roadbed for additional stability. Geotextile selection shall be based on AASHTO M288-98 specification:
1. For subgrades with a CBR greater than or equal to 3 or shear strength greater than 90 kPa, geotextile must meet requirements of section AASHTO M288-96 Section 7.3, Separation Requirements.
2. For subgrades with a CBR between 1 and 3 or sheer strength between 30 and 90 kPa, geotextile must meet requirements of section AASHTO M288-96 Section 7.4, Stabilization Requirements.
A 6-inch course of coarse aggregate shall be applied immediately after grading or the completion of utility installation within the right-of-way. In areas experiencing "heavy duty" traffic situations, stone should be placed at an 8 to 10 inch depth to avoid excessive dissipation or maintenance needs.
All roadside ditches, cuts, fills, and disturbed areas adjacent to parking areas and roads shall be stabilized with appropriate temporary or permanent vegetation according to specification in Ds2 and Ds3 - Disturbed Area Stabilization (With Temporary Seeding) and Disturbed Area Stabilization (With Permanent Vegetation).
6-88

PERMANENT ROADS AND PARKING AREAS
Permanent roads and parking areas shall be designed and constructed according criteria established by the Georgia Department of Transportation or local authority. Permanent roads and parking areas shall be stabilized in accordance with this specification, applying an initial base course of gravel immediately following grading.
CONSTRUCTION SPECIFICATIONS
1. Trees, stumps, roots, brush, weeds, and other objectionable materials shall be removed from the work area.
2. Unsuitable material shall be removed from the roadbed and parking areas
3. Grading, subgrade preparation, and compaction shall be done as needed. Fill material shall be deposited in layers not to exceed 9 inches and compacted with the controlled movement of compacting and earth moving equipment.
4. The roadbed and parking area shall be graded to the required elevation. Subgrade preparation and placement of the surface course shall be in accordance with sound highway construction practice.
5. Structures such as culverts, pipe drops, or bridges shall be installed to the lines and grades shown on the plans or as staked in the field. Pipe conduits shall be placed on a firm foundation. Selected backfill material shall be placed around the conduit in layers not to exceed 6 inches. Each layer shall be properly compacted.
6. Roads shall be planned and laid out according to good landscape management principles.
MAINTENANCE
Roads and parking areas may require a periodic top dressing of gravel to maintain the gravel depth at 6 inches. Vegetated areas should be checked periodically to ensure a good stand of vegetation is maintained. Remove any silt or other debris causing clogging of roadside ditches or other drainage structure.
GaSWCC (Amended - 2000)

Stream Diversion

Channel

Dc

DEFINITION
A temporary channel constructed to convey flow around a construction site while a permanent structure is being constructed in the stream channel.
PURPOSE
To protect the streambed from erosion and allow work "in the dry".
CONDITIONS
Temporary stream diversion channels shall be used only on flowing streams with a drainage area less than one square mile. Structures or methodology for crossing streams with larger drainage areas should be designed by methods which more accurately define the actual hydrologic and hydraulic parameters which will affect the functioning of the structure.

PLANNING CONSIDERATIONS
Linear projects, such as utilities or roads, frequently cross and impact live streams creating a potential for excessive sediment loss into a stream by both the disturbance of the approach areas and by the work within the streambed and banks.
In cases where in-stream work is unavoidable, the amount of encroachment and time spent working in the channel shall be minimized. If construction in the streambed will take an extended period of time, substantial in-stream controls or stream diversion channel should be considered to prevent excessive sedimentation damage. To limit land-disturbance, overland pumping of the stream should be considered in low-flow conditions. Clearing of the stream bed and banks shall be kept to a minimum.
DESIGN CRITERIA
Drainage Area
Temporary stream diversion channels shall not be used on streams with a drainage area greater than one square mile (640 acres).
Size
The bottom width of the stream diversion shall be a minimum of six feet or equal to the bottom width of the existing streambed, whichever is greater.
Side Slopes
Side slopes of the stream diversion channel shall be no steeper than 2:1.

Table 6-12.1. Stream Diversion Channel Linings

Lining Materials
Geotextile, polyethylene film, or sod
Geotextile alone
Class I riprap and geotextile

Symbol
Dc-A
Dc-B Dc-C

Acceptable Velocity Range
0 - 2.5 fps
2.5 - 9.0 fps 9.0 - 13.0 fps

GaSWCC (Amended - 2000)

6-89

Depth and Grade
Depth and grade may be variable, dependent on site conditions, but shall be sufficient to ensure continuous flow of water in the diversion.
Channel Lining
A stream diversion channel shall be lined to prevent erosion of the channel and sedimentation in the stream. The lining is selected based upon the expected velocity of bankfull flow. Table 6-12.1 shows the selection of channel linings that may be used. Refer to specification Mb Matting and Blankets.
Geotextile
Geotextiles should be used as a protective cover for soil or, if the channel is to be lined with rip-rap, as a separator between graded stone and the soil base. The geotextile will prevent erosion of the channel and the migration of soil particles from the subgrade into the graded stone. The geotextile shall be specified in accordance with AASHTO M288-96 Section 7.5, Permanent Erosion Control Recommendations. The geotextile should be placed immediately adjacent to the subgrade without any voids.
CONSTRUCTION SPECIFICATIONS
1. The channel shall be excavated, constructing plugs at both ends. Plugs can be constructed of compacted soil, riprap, sandbags or sheet piling.
2. Silt fence or a berm shall be placed along the sides of the channel to prevent unfiltered runoff from entering the stream. The berm can be constructed using the material excavated for the stream diversion.
3. The channel surface shall be smooth (to prevent tearing of the liner) and lined with the material specified in the plans. The outer edges of the geotextile shall be secured at the top of the channel with compacted soil.
4. The plugs are removed when the liner installation is complete, removing the downstream plug first.
5. As soon as construction in the streambed is complete, the diversion shall be replugged and backfilled. The liner should be inspected for damage and salvaged if possible.
6. Upon removal of the lining, the stream shall immediately be restored and properly stabilized.
6-90

MAINTENANCE
The stream diversion channel shall be inspected at the end of each day to make sure that the construction materials are positioned securely. This will ensure that the work area stays dry and that no construction materials float downstream. All repairs shall be made immediately.
GaSWCC (Amended - 2000)

VEHICULAR STREAM CROSSING.
(TO BE LOCATED AT ORIGINAL STREAMBED FOR INITIAL CROSSINGS)

SILT FENCE

FORMER LOCATION OF FLOW BARRIER

FLOW

PLACE
RIPRAP AT TRANSITION

FLOW FLOW

A

FLOW BARRIER

ORIGINAL STREAM-
BED

FLOW
A

FORMER LOCATION OF FLOW BARRIER

FLOW BARRIER (RIPRAP, SANDBAGS, PLYWOOD, JERSEY BARRIERS OR SHEET PILING)
PLACE RIPRAP AT TRANSITION

FLOW

Figure 6-12.1. Stream Diversion Channel (perspective view)
GaSWCC (Amended - 2000)

6-91

SILT FENCE EXISTING GROUND

POST

POST

TYPE A DIVERSION

POLYETHYLENE (6 MIL. MIN.) OR
GRASS LINER
2:1

2:1

*

SILT FENCE
EXISTING GROUND
* *

EXISTING GROUND EXISTING GROUND

TYPE B DIVERSION
RIPRAP FILTER CLOTH
2:1
*
TYPE C DIVERSION
RIPRAP FILTER CLOTH ROCK OR SANDBAG LINER
2:1

2:1

2:1

EXISTING GROUND EXISTING GROUND

*
* 6' MINIMUM OR WIDTH OF EXISTING STREAM WHICHEVER IS LESS ** ENTRENCH SILT FENCE AND FILTER CLOTH IN SAME TRENCH

Figure 6-12.2. Stream Diversion Channel Linings

6-92

GaSWCC (Amended - 2000)

Diversion

Di

DEFINITION
A ridge of compacted soil, constructed above, across or below a slope.
PURPOSE
To reduce the erosion of steep, or otherwise highly erodible areas by reducing slope lengths, intercepting storm runoff and diverting it to a stable outlet at a nonerosive velocity.
CONDITIONS
Diversions are applicable when:
1. Runoff from higher areas is or has potential for damaging property, causing erosion, contributing to pollution, flooding, interfering with or preventing the establishment of vegetation on lower areas.
2. Surface and/or shallow subsurface flow is damaging sloping upland.
3. The length of slope needs to be reduced so that soil loss will be reduced to a minimum.
This standard applies to temporary and permanent diversions in developments involving land-disturbing activities.
DESIGN CRITERIA
Location
Diversion location shall be determined by considering outlet conditions, topography, land use, soil type, length of slope, seep planes (when seepage is a problem), and the development layout. Diversions should be tailored to fit the conditions for a particular field and local soil type(s).
GaSWCC (Amended - 2000)

A diversion consists of two components that must be designed - the ridge and the channel.
Ridge Design
The ridge shall be compacted and designed to have stable side slopes, which shall not be steeper than 2:1. The ridge shall be a minimum width of four feet at the design water elevation after settlement. Its design shall allow ten percent for settlement.
Channel Design
Land slope must be taken into consideration when choosing channel dimensions. On the steeper slopes, narrow and deep channels may be required. On the more gentle slopes, broad, shallow channels usually are applicable. The wide, shallow section will be easier to maintain. Since sediment deposition is often a problem in diversions, the designed flow velocity should be kept as high as the channel lining will permit.
Table 6-13.1 indicates the storm frequency required for the design of the diversion. The required storm frequency is based on the purpose of the diversion. The storm frequency is used to determine the required channel capacity, Q (peak rate of runoff).
The channel portion of the diversion may have a parabolic or trapezoidal cross-section. Detailed information for the design of these channels is provided in the specification Wt - Stormwater Conveyance Channel.
Outlets
Each diversion must have an adequate outlet. The outlet may be a constructed or natural waterway, a stabilized vegetated area or a stabilized open channel. In all cases, the outlet must discharge in such a manner as to not cause an erosion problem. Protected outlets shall be constructed and stabilized prior to construction of the diversion.
Stabilization
Channels shall be stabilized in accordance with item 5 of the construction specifications on page 6-94.
DIVERSIONS FOR ROADS AND UTILITY RIGHTSOF-WAY
A detailed design is not required for this type of diversion. Diversions installed to divert water off a road or right-of-way shall consist of a series of compacted ridges of soil running diagonally across the road at a 30 angle. Ridges are constructed by excavating a channel upstream for this type of diversion.
6-93

The compacted ridge height shall be 8-12" above the original road surface; the channel depth shall be 8-12" below the original road surface. Channel bottoms and ridge tops shall be smooth enough to be crossed by vehicular traffic. The maximum spacing between diversions shall be as follows:

Road Grade (Percent) 1 2 5 10 15 20

Distance Between Diversions (Feet) 400 250 125 80 60 50

Stable outlets shall be provided for each diversion.

8"-12"

Compacted Earth Ridge

ECxchaavnanteeld

8"-12"

Original Road Surface

6' - 12'
Figure 6-13.1. Typical Diversion Across Road

CONSTRUCTION SPECIFICATIONS
1. All trees, brush, stumps, obstructions, and other objectionable material shall be removed and disposed of so as not to interfere with the proper functioning of the diversion.
2. The diversion shall be excavated or shaped to line, grade, and cross section as required to meet the criteria specified herein and free of irregularities which will impede normal flow.
3. All fills shall be machine compacted as needed to prevent unequal settlement that would cause damage in the completed diversion.
4. All earth removed and not needed in construction shall be spread or disposed of so that it will not interfere with the functioning of the diversion.
5. Diversion channel shall be stabilized in accordance with specification Ch - Channel Stabilization.

Table 6-13.1. Diversion Design Criteria

Diversion Type
Temporary

Land or Improvement Protected
Construction areas Building sites

Storm1 Frequency
10 years2

Freeboard 0.3'

Minimum Top Width
4 feet

Landscaped, recreation

25 years

0.3'

and similar areas.

Permanent

Dwellings, schools,

commercial bldgs.,

50 years

0.5'

and similar installations.

4 feet 4 feet

1 Use 24-hour storm duration 2 Use 10 years or the storm frequency specified in Title 12 of the Official Code of Georgia Annotated

6-94

GaSWCC (Amended - 2000)

TO BE SHOWN ON THE EROSION AND SEDIMENT CONTROL PLAN
Complete the appropriate detail drawing for the channel cross-section of choice:

Top width = ____ ft

Ridge width =____ ft (4 ft minimum)

_____ Lining

~3:1 Freeboard =_____ft

Ridge height =____ ft

Depth of flow =_____ ft

Normal Ground Level

Freeboard =_____ft

Ridge width =____ ft (4 ft minimum)

Normal Ground Level

6"
Sideslope =___ :1

Depth of flow =_____ft

Sideslope =___:1

Bottom width =____ ft

_____ Lining

~3:1

Ridge height =____ ft

Freeboard =_____ft

Ridge width =____ ft (4 ft minimum)

Normal Ground Level

6"
Sideslope =___ :1

Depth of flow =_____ft

Sideslope =___:1

_____ Lining

~3:1

Ridge height =____ ft

GaSWCC (Amended - 2000)

6-95

6-96

GaSWCC (Amended - 2000)

Temporary Downdrain

Structure

Dn1

DEFINITION
A temporary structure used to convey concentrated storm water down the face of cut or fill slopes.
PURPOSE
To safely conduct storm runoff from one elevation to another without causing slope erosion and allowing the establishment of vegetation on the slope.
CONDITIONS
Temporary downdrains are used on slopes where a concentration of storm water could cause erosion damages. These structures are removed once the permanent stormwater disposal system is installed.
DESIGN CRITERIA
Formal design is not required.The following standards shall be used:
Placement
The temporary downdrain shall be located on undisturbed soil or well-compacted fill.
Diameter
The diameter of the temporary downdrain shall provide sufficient capacity required to convey the maximum runoff expected during the life of the drain. Refer to Table 6-14.1 for selecting pipe sizes.

Table 6-14.1. Pipe Diameter for Temporary Downdrain Structure

Maximum Drainage Area Per Pipe (acre)
0.3 0.5 1.0

Pipe Diameter (inches)
10 12 18

Downdrain Inlet and Outlet
Diversions are used to route runoff to the downdrain's Tee or "L" inlet at the top of the slope. Slope the entrance 1/2" per foot toward the outlet. Thoroughly compact selected soil around the inlet section to prevent the pipe from being washed out by seepage or piping. A stone filter ring or check dam may be placed at the inlet for added sediment filtering capacity. Refer to Cd Check Dam and Fr - Stone Filter Ring. These sediment filtering devices should be removed if flooding or bank overwash occurs.
Rock riprap shall be placed at the outlet for energy dissipation. A Tee outlet, flared end section, or other suitable device may be used in conjunction with the riprap for additional protection. See Figure 6-14.1. Refer to St - Storm Drain Outlet Protection.
Pipe Material
Design the slope drain using heavy-duty, flexible materials such as non-perforated, corrugated plastic pipe or specially designed flexible tubing. Use reinforced, hold-down grommets or stakes to anchor the pipe at intervals not to exceed 10 feet with the outlet end securely fastened in place. The pipe must extend beyond the toe of the slope.
CONSTRUCTION SPECIFICATIONS
A common failure of slope drains is caused by water saturating the soil and seeping along the pipe. This creates voids from consolidation and piping causes washouts. Proper back-filling around and under the pipe "haunches" with stable soil material and hand compacting in 6-inch lifts to achieve firm contact between the pipe and the soil at all points will eliminate this type of failure.
1. Place slope drains on undisturbed soil or wellcompacted fill at locations and elevations shown on the plan.
2. Slightly slope the section of pipe under the dike toward its outlet.

GaSWCC (Amended - 2000)

6-97

3. Hand tamp the soil under and around the entrance section in lifts not to exceed 6 inches.
4. Ensure that fill over the drain at the top of the slope has minimum dimensions of 1.5 ft. depth, 4 ft. top width, and 3:1 side slopes.
5. Ensure that all slope drain connections are watertight.
6. Ensure that all fill material is well-compacted. Securely fasten the exposed section of the drain with grommets or stakes spaced no more than 10 feet apart.
7. Place the drain slightly diagonally across the slope, extending the drain beyond the toe of the slope. Curve the outlet uphill and adequately protect the outlet from erosion.
8. If the drain is conveying sediment-laden runoff, direct all flows into a sediment trap or sediment basin.

9. Make the settled, compacted dike ridge no less than one foot above the top of the pipe at every point.
10. Immediately stabilize all disturbed areas following construction.
MAINTENANCE
Inspect the slope drain and supporting diversion after every rainfall and promptly make necessary repairs. When the protected area has been permanently stabilized and the permanent stormwater disposal system is fully functional, temporary measures may be removed, materials disposed of properly, and all disturbed areas stabilized appropriately. Refer to specifications Ds3 and Ds4 - Disturbed Area Stabilization (With Permanent Vegetation and Sodding), respectively, and Mb - Matting and Blankets.

TO BE SHOWN ON THE EROSION AND SEDIMENT CONTROL PLAN
1. The drainage area for each downdrain, in acres. 2. The diameter of each downdrain, in inches, based on Table 6-14.1. 3. The dimensions of the outlet protection, including flow rate, velocity, and apron length, upstream
and downstream widths, average stone diameter and depth.

6-98

GaSWCC (Amended - 2000)

Stabilized outlet

Diversion dike
Hold-down stakes

4' min

Island over inlet
3:1 1.5' min

Min. 10' spacing

Plastic corrugated pipe

4' min
Level section

Top of diversion

Natural ground

1' min

Diversion channel

4' min 1.5' min

Top of hand-compacted fill (island)
0.5' min 3:1

Outlet Pipe
Inlet Detail

Make all pipe connections watertight and secure so that the joints will not separate in use.

DOWNDRAIN PIPE AND INLET DETAIL

GaSWCC (Amended - 2000)

Figure 6-14.1

6-99

6-100

GaSWCC (Amended - 2000)

Permanent Downdrain

Structure

Dn2

DEFINITION
A permanent structure to safely convey surface runoff from the top of a slope to the bottom of the slope.
PURPOSE
The purpose of this standard is to convey storm runoff safely down cut or fill slopes to minimize erosion.
CONDITIONS
Several types of structures may be used as a permanent downdrain. All structures shall satisfy the standards and specification set forth by the Georgia Department of Transportation.The following types of structures may be used:
Paved Flume
The paved flume may have a parabolic, rectangular or trapezoidal cross-section.
Pipe
The pipe may be constructed of materials including steel, plastic, etc..
Sectional
A prefabricated sectional conduit of half round or third round pipe may be used.
Downdrain structures are to be used where concentrated water will cause excessive erosion on cut and fill slopes.

DESIGN CRITERIA
Permanent downdrain structures should be designed by professionals familiar with these structures.
Capacity
Flumes shall be adequately designed to safely convey runoff water concentrations down steep slopes based on a minimum 25-year, 24-hour storm in accordance with criteria in Appendix A of this manual.
Slope
The slope shall be sufficient to prevent the deposition of sediment.
Outlet Stabilization
Outlets must be stabilized using criteria in St - Storm Drain Outlet Protection.
MAINTENANCE
Inspect for damage after each rainfall.

GaSWCC (Amended - 2000)

6-101

6-102

GaSWCC (Amended - 2000)

Filter Ring

Fr

DEFINITION

A temporary stone barrier constructed at storm drain inlets and pond outlets.

PURPOSE

This structure reduces flow velocities, preventing the failure of other sediment control devices. It also prevents sediment from leaving the site or entering drainage systems, prior to permanent stabilization of the disturbed area.

CONDITIONS

Filter rings shall be used in conjunction with other sediment control measures, except where other practices defined in this manual are not appropriate (such as inlets to concrete flumes). They can be installed at or around devices such as inlet sediment traps, temporary downdrain inlets, and detention pond retrofits to provide additional sediment filtering capacity.

DESIGN CRITERIA

Formal design is not required.The following standards shall be used:

Location

The filter ring shall surround all sides of the structure receiving runoff from disturbed areas. It should be placed a minimum of four feet from the structure. The ring is not intended to substantially impound water, causing flooding or damage to adjacent areas.

The filter ring may also be placed below storm drains discharging into detention ponds, creating a centralized area, or "forebay", for sediment accumulation. This provides for easier, more localized clean-out of the pond. If utilized above a retrofit structure, it should be a minimum of 8 to 10 feet from the retrofit.

Stone Size

When utilized at inlets with diameters less than 12 inches, the filter ring shall be constructed of stone no smaller than 3-5 inches (15 - 30 lbs.).

When utilized at pipes with diameters greater than 12 inches, the filter ring shall be constructed of stone no smaller than 10-15 inches (50 - 100 lbs.).

The larger stone can be faced with smaller filter stone on the upstream side for added sediment filtering capabilities. However, the smaller filter stone is more prone to clogging, requiring higher maintenance.
Height
The filter ring shall be constructed at a height no less than two feet from grade.
CONSTRUCTION SPECIFICATIONS
Mechanical or hand placement of stone shall be required to uniformly surround the structure to be supplemented. Refer to Appendix C for rock riprap specifications.
The filter ring may be constructed on natural ground surface, on an excavated surface, or on machine compacted fill.
A common failure of filter rings is caused by their placement too close or too high above the structure it is enhancing. When utilized below a storm drain outlet, it shall be placed such that it does not create a condition causing water to back-up into the storm drain and inhibit the function of the storm drain system.
MAINTENANCE
The filter ring must be kept clear of trash and debris. This will require continuous monitoring and maintenance, which includes sediment removal when one-half full. Structures are temporary and should be removed when the land-disturbing project has been stabilized.

GaSWCC (Amended - 2000)

6-103

Minimum 8' - 10' 50# - 150# Stone Rip-Rap

2'-0" Min.

STONE FILTER RING
Figure 6-15.1

6-104

GaSWCC (Amended - 2000)

Gabion

Ga

DEFINITION
Gabions are large, multi-celled, welded wire or rectangular wire mesh boxes, used in channel revetments, retaining walls, abutments, check dams, etc.
PURPOSE
Rock-filled baskets, properly wired together, form flexible monolithic building blocks used for construction of erosion control structures. Gabions are used to stabilize steep or highly erosive slopes.
DESIGN CRITERIA
Construction plans and drawings should be prepared by professionals familiar with the use of gabions. Erosion and sediment control construction design should ensure that foundations are properly prepared to receive gabions, that the gabion structure is securely "keyed" into the foundations and abutment surfaces, and that rock used is durable and adequately sized to be retained in the baskets.
CONSTRUCTION SPECIFICATIONS
How the Gabion is Filled
The gabion is usually filled with 4 - 8 inch pieces of stone, preferably placed by hand, but sometimes dumped mechanically, into the basket. Hand-packing allows the complete filling of the basket; allowing the basket to gain strength and maintain its integrity. The filled gabion then becomes a large, flexible, and permeable building block from which a broad range of structures may be built. This is done by setting and wiring individual units together in courses and filling them in place. Details are provided by the manufacturer.
GaSWCC (Amended - 2000)

Geotextiles
It is recommended that geotextiles be used behind all gabion structures. Geotextiles shall be specified in accordance with AASHTO M288-96 Section 7.5, Permanent Erosion Control Requirements.
If there is seepage flow or unidirectional flow from the protected soil mass, the appropriate geotextile should be selected based on an appropriate filter design to prevent the build-up of hydrostatic pressure behind the geotextile.
Corrosion Resistance of Gabions
The wire mesh or welded wire used in gabions is heavily galvanized. For highly corrosive conditions, a PVC (polyvinyl chloride) coating must be used over the galvanizing. Such treatment is an economical solution to deterioration of the wire near the ocean, in some industrial areas, in polluted streams, and in soils such as muck and peat. However, extra care should be taken during construction and installation because the corrosion resistance of the baskets is compromised if the PVC coating is chipped-off. Also, baskets manufactured completely of plastic are available.
Flexibility
An outstanding advantage of the gabion is its flexibility of application. This property is especially important when a structure is on unstable ground or in areas where scour from waves or currents can undermine it.
Durability
Gabions are durable because they support plant growth which develops a living coating for the wire mesh and stones. After the first few years, the strength of the structure may be enhanced by the soil, silt, and roots that fill the voids between the individual stones.
Strength
Steel wire baskets have the strength and flexibility to withstand forces generated by water and earth masses. Also, the pervious nature of the gabion allows it to absorb and dissipate much of the energy developed. This is particularly so on coast protection installations where a compact gabion structure often remains long after a massive rigid structure fails.
6-105

Permeability
Hydrostatic heads do not develop behind a gabion wall. The wall is pervious to water and stabilizes a slope by the combined action of draining and retaining. Drainage is accomplished by gravity and by evaporation as the porous structure permits active air circulation through it. Moreover, as plant growth invades the structure, transpiration further assists in removing moisture from the backfill. This system is much more efficient than weep holes in standard masonry walls.
Economy
Gabion installations are more economical than rigid or semi-rigid structures for a number of reasons. The following are among the more important ones.
Little maintenance is required.
Gabion construction is simple and does not require skilled labor.
Preliminary foundation preparation is unnecessary; the surface needs only to be reasonably level and smooth.
No costly drainage provision is required because of the gabion's porosity.
Landscaping
Because gabions permit the growth of natural vegetation and maintain the natural environment of the area, they provide attractive and natural building blocks for decorative landscaping.
They can be used effectively and economically in parks, along highways, including use as a sound barrier, and around bridge approaches to create walkways, rock gardens, patios, and terraces ... to beautify the banks of lakes and ponds ... to accent trees and other plantings.
In fact, their application to decorative landscaping is limited only by the ingenuity of the landscaper.

Typical Installations

River training and flood control:

Gabion aprons Longitudinal works Training walls Revetments Bank paving

Counterforts Drop structures or
weirs Spurs, spur dikes,
or groins

Channel linings

Retaining walls

Bridge abutments and wings

Marinas and boat ramps

Culvert headwalls and outlet aprons

Shore and beach protection

MAINTENANCE

Periodic inspection should be performed for signs of undercutting or excessive erosion at transition areas.

Source: National Crushed Stone Association

6-106

GaSWCC (Amended - 2000)

Grade Stabilization

Gr

Structure

DEFINITION
A structure to stabilize the grade in natural or artificial channels.
PURPOSE
Grade stabilization structures are installed to stabilize the grade in natural or artificial channels, prevent the formation or advance of gullies, and reduce erosion and sediment pollution.
CONDITIONS
This standard applies to sites where structures are needed to stabilize channel grades but does not apply to sites where water is to be impounded.
DESIGN CRITERIA
Structures
Structures constructed of concrete, rock, masonry, steel, aluminum or treated wood or by soil bioengineering methods shall be designed in accordance with sound engineering practices. Design data for small reinforced concrete drop spillways and formless concrete chute spillways are contained herein.
Geotextile should be placed under stabilization structures such as revetment mats and riprap as part of a permanent erosion control system.The geotextile should be selected/specified in accordance with AASHTO M288-96 Section 7.5, Permanent Erosion Control.

Capacity

The condition of adjacent areas is considered when determining the storm frequency used to design the grade stabilization structure. Structures shall be designed to protect areas from overbank flow damage up to and including storm frequencies specified in Table 616.1.
Table 6-16.1

Adjacent Area

Storm Frequency

Residences, commercial buildings, recreation buildings, etc.
Recreation and landscaped areas
Agricultural land

100-year, 24-hour storm
25-year,2 24-hour storm1
25-year,2 24-hour storm1

1 50 percent of peak flood flow may be carried around island-type structures provided overbank flow damage from erosion and flooding can be tolerated. Peak flood flow will be determined by methods contained in Appendix A.
2 Or the storm frequency specified in Title 12 of the Official Code of Georgia Annotated.

Embankment

Earthfill embankments shall have a minimum top width of 10 feet and side slopes of 3:1 or flatter.

Keyway

A keyway no less than 8 feet wide and 2 feet deep shall be constructed along the centerline of the structure and embankment.

Outlet

All structures shall discharge into stable outlets.

CONSTRUCTION SPECIFICATIONS

Excavations shall be dewatered prior to filling.

Structures shall be placed on compacted earthfill. Earthfill material shall be moderately to slowly permeable with the most plastic being used in the center of the embankment and adjacent to structures. Materials shall be constructed in 6 - 8 inch horizontal lifts and compacted to approximately 95% of standard density. The embankment shall be overbuilt 10% in height to allow for settlement. Embankment surfaces shall be completed to the required lines and grades.

GaSWCC (Amended - 2000)

6-107

Protective cover shall be applied immediately after completion of the structure. Refer to specifications Ds3 and Ds4 - Disturbed Area Stabilization (With Permanent Vegetation and Sodding), respectively, and Mb - Matting and Blankets.

CONTROLLED HEAD (feet)

DISCHARGE (cfs)

10

25

50

100 150 200 400 800 1500

4 Drop spillways or
Hooded inlet spillways 8
12
16 Hooded inlet or
Pipe drop inlet spillways 20
25
30

Drop spillways
Drop or chute spillways

Monolithic drop inlet spillways

Chute spillways

40 Pipe drop inlet spillways
80

Note: Chart shows most economical structure as related to discharge and controlled head providing site conditions are adequate.
Figure 6-16.1

6-108

GaSWCC (Amended - 2000)

Inlet Channel Crest
Headwall Extension Cut-off Wall Footings

Headwall

Sidewall

Apron

Wingwall

Toe Wall Floor Blocks

Outelert CChhaannnneell

STRAIGHT DROP SPILLWAY
Figure 6-16.2

Planning and design of straight drop spillways normally require the assistance of an engineer. Local personnel may be trained to plan and install small drop spillway structures when standard plans are available.
Measurement locations for symbols F (overfall in feet), h (depth of weir in feet), s (depth of stilling pool in feet), and L (length of weir in feet) are shown in Figure 6-16.3

L h
HEADWALL F s

HEADWALL EXTENSION
WINGWALL

DOWNSTREAM ELEVATION
Figure 6-16.3 - Symbols For Straight Drop Spillway
Weir capacities for low-overall straight drop spillways can be determined from figure 6-16.4 for various combinations of F, h, and L.

GaSWCC (Amended - 2000)

6-109

Discharge capacity, Q, in cfs.

F = 3 ft.
700

600

500

400

h=3'-0"

300

h=2'-6"

200

h=2'-0"

100

0 6 8 10 12 14 16 18 20 22 24 26 28 30
Length of weir, L, in ft.

Discharge capacity, Q, in cfs.

F = 4 ft.

700

600

h=4'-0"

500

h=3'-6"

400

h=3'-0"

300

h=2'-6"

200

h=2'-0"

100

0 6 8 10 12 14 16 18 20 22 24 26 28 30
Length of weir, L, in ft.

F = 5 ft.
900

F = 6 ft.
900

h=5'-0"

h=5'-0"
Discharge capacity, Q, in cfs.

Discharge capacity, Q, in cfs.

800

800

700

h=4'-6"

700

h=4'-6"

600

h=4'-0"

600

h=4'-0"

500

h=3'-6"

500

h=3'-6"

400

h=3'-0"

400

h=3'-0"

300

h=2'-6"

300

h=2'-6"

200

h=2'-0"

200

h=2'-0"

100

100

0 6 8 10 12 14 16 18 20 22 24 26 28 30
Length of weir, L, in ft.

0 6 8 10 12 14 16 18 20 22 24 26 28 30
Length of weir, L, in ft.

Note: h = total depth of weir, in feet (including freeboard)
c = net drop from crest to top of transverse sill, in feet (For type B drops keep h F less than 0.75)
Q =

3.1 L h 3 2 (1.10 + 0.01 F)

6-110

WEIR CAPACITY FOR STRAIGHT DROP SPILLWAYS

Figure 6-16.4

GaSWCC (Amended - 2000)

TRASH RACK

INLET

ANTI-SEEP COLLARS

PIPE CONDUIT

CRADLE

CANTILEVER OUTLET

TOE DRAIN

OUTLET SUPPORT

ROCK RIP-RAP STILLING POOL

DROP INLET SPILLWAY

Figure 6-16.5

Inlet Channel
Crest
Endwall
Headwall CuWt-aolflf

Top of Fill Sidewall

Apron Endsill
Toe Wall

Outlet Channel

GaSWCC (Amended - 2000)

BOX INLET DROP SPILLWAY
Figure 6-16.6

6-111

WING WALL

FOOTING

ISNTLREATIGHT

ANTI-SEEP COLLAR

VSEERCTTIICOANL CURVE

EXPANSION JOINT

CHANNEL SIDE WALL

FLOOR

SAF OUTLET WING WALL
CHUTE SPILLWAY
Figure 6-16.7

TOE WALL

6-112

GaSWCC (Amended - 2000)

GaSWCC (Amended - 2000)

Figure 6-16.8

2'-0" 2'-0" 9"

C

C

9" 3'-3" 2'-0"

2'-3" 9"

3'-0"

L2

HALF PLAN

5'-0"
1 1

2'-0"

L2
CL

3'-0"

L2

HALF ELEVATION

3'-0"

2'-0"

5"

4'-0" A 1 1
2"
A 2"
6"

A

B
1'-6"

1'-5"

5"

1

2"

1"

B 6'-0"

1

2"

1

2'-0"Rod 2" A

For Reinforcing

See Note B

6"

3'-"

LONGITUDINAL SECTION ON CL

STRUCTURAL DETAILS

3'-0" 5" 2'-0" H*

L2

5'-0"

5 "

5 "

5 "

1 1
6"
SECTION C-C
1" 1
CL
SECTION B-B
For backfill See Note E
1" 1
CL
SECTION A-A

1'-6" 5"

5'-0"

2'-0"

2'-0" 5"

NOTES: A. Use 5 inch thickness of concrete throughout except
as dimensioned otherwise.
B. Reinforcing as indicated shall be (1) 3/8" reinforcing steel 12" o.c. both ways; or (2) No.2 gauge welded wire fabric 6" o.c. both ways (common designation 6x6 2/2). Reinforcing bars or mesh should be lapped one foot at all joints.
C. Spillways of this type shall be constructed on solid ground. Seep areas should be avoided or properly drained with a carefully constructed toe drainage system.
D. This spillway shall not be used as a part of a water impounding structure.
E. The disturbed area adjacent to the spilway shall be backfilled, compacted and sodded.
F. The length (L) of the spillway shall be limited by the amount of concrete that can be adequately mixed, placed and finished in one day's time with the labor and equipment available or a max. L=8'-0"
G. The maximum "H" for this spillway is 5'-0"

Discharge Capacity of Spillway in c.f.s.

Length of Crest(L) in feet

2 4 68

with no freeboard

30 45 60 75

with 6" freeboard

18 28 38 48

Concrete Volumes in Cubic Yards

Head "H" Feet

Length of Crest(L) in feet

2' - 0"

4' - 0"

6' - 0"

8' - 0"

4' - 0"

3.5

4.2

4.9

5.6

5' - 0"

3.7

4.4

5.2

6.0

Typical Plan - Formless Concrete Chute

6-113

PREFABRICATED METAL STRUCTURE Figure 6-16.9

6-114

SHEET PILING HEADWALL WITH SAND-CEMENT BAG SIDEWALLS AND APRON.
SMALL, LOW COST WATER CONTROL STRUCTURES
Figure 6-16.10
GaSWCC (Amended - 2000)

Level Spreader

Lv

DEFINITION
A storm flow outlet device constructed at zero grade across the slope whereby concentrated runoff may be discharged at non-erosive velocities onto undisturbed areas stabilized by existing vegetation.
PURPOSE
To dissipate storm flow energy at the outlet by converting storm runoff into sheet flow and to discharge it onto areas stabilized by existing vegetation without causing erosion.
CONDITIONS
Where sediment-free storm runoff is intercepted and diverted onto undisturbed stabilized areas (i.e., at diversion outlets, etc.). This practice applies only in those situations where the spreader can be constructed on undisturbed soil and where the area directly below the level lip is stabilized by existing vegetation. The water must not be allowed to reconcentrate below the point of discharge.
DESIGN CRITERIA
Length
A specific design for level spreaders will not be required. However, spreader length will be determined by estimating the peak stormflow from the 10-year, 24-hour storm or the storm specified in Title 12 of the Official Code of Georgia Annotated and selecting the appropriate length from Table 6-17.1.
Outlets
Final discharge will be over the level lip onto an undisturbed, stabilized area. The outlet shall be generally smooth to create uniform sheet flow.
GaSWCC (Amended - 2000)

Table 6-17.1

Designed Q10/24 (cfs)
up to 10 11 to 20 21 to 30 31 to 40 41 to 50

Minimum Length "L" (feet) 10 20 30 40 50

CONSTRUCTION SPECIFICATIONS

The minimum acceptable width shall be 6 feet. The depth of the level spreader as measured from the lip shall be at least 6 inches and the depth shall be uniform across the entire length of the measure.

The grade of the channel for the last 15 feet of the dike or diversion entering the level spreader shall be less than or equal to 1%.

The level lip shall be constructed on zero percent grade to insure uniform spreading of storm runoff (converting channel flow to sheet flow). For calculation purposes, a grade of 0.1% may be needed, however, the level spreader shall be installed at zero percent grade.

Level spreaders must be constructed on undisturbed soil (not on fill).

The entrance to spreader shall be graded in a manner to insure that runoff enters directly onto the zero percent graded channel.

Storm runoff converted to sheet flow must discharge onto undisturbed stabilized areas.

All disturbed areas shall be vegetated immediately after construction is completed. Refer to specifications Ds3 and Ds4 - Disturbed Area Stabilization (With Permanent Vegetation and Sodding), respectively and Mb - Matting and Blankets.

MAINTENANCE

Periodic inspection and maintenance must be provided.

6-115

Undisturbed Soil

2:1 or Flatter

6" Min. 6' Min.

SECTION A-A

0% Channel Grade

A

Maximum Grade of 1% for a Transition of 15' Minimum

6' Min. A

Diversion or Dike

L

PLAN

Vegetated Diversion

Transition to 0 grade

Stable undisturbed outlet

Stabilized Slope

6-116

ISOMETRIC VIEW - (Not to Scale)
LEVEL SPREADER
Figure 6-17.1

GaSWCC (Amended - 2000)

Rock Filter Dam

Rd

DEFINITION
A permanent or temporary stone filter dam installed across small streams or drainageways.
PURPOSE
This structure is installed to serve as a sediment filtering device in drainageways. In some cases, it may also reduce the velocity of stormwater flow through a channel. This structure is not intended to substantially impound water. Before structures of any kind are installed in flowing streams, the appropriate agencies and local officials should be contacted.
CONDITIONS
This practice is applicable for use in small channels which drain 50 acres or less. The rock filter dam must be used in conjunction with other appropriate sediment control measures to reduce the amount of sediment reaching the channel. This practice may be used:
1. as an additional sediment control measure below construction projects such as culvert installations, dam construction, or any project that may involve grading activity directly in a stream, or
2. at the upstream end of ponds or lakes to trap incoming sediment loads.
DESIGN CRITERIA
Formal design is not required, but it is recommended that a qualified engineer be consulted before a structure of any kind is installed in a flowing stream. (Refer to Figure 6-18.1)
The following standards shall be followed:
GaSWCC (Amended - 2000)

Drainage Area
The drainage area to the dam shall not exceed 50 acres.
Height
The dam should not be higher than the channel banks or exceed the elevation of the upstream property line. The center of the rock dam should be at least six inches lower than the outer edges of the dam at the channel banks.
Side Slopes
The side slopes shall be 2:1 or flatter.
Location
The dam shall be located as close to the source of sediment as possible and so that it will not cause water to back up on upstream adjacent property.
Stone Size
The stone size shall be determined by the design criteria established in Riprap - Appendix C. The rock dam can be faced with smaller stone on the upstream side for additional filtering effect. However, this may make the dam more prone to clogging.
Top Width
The width across the top of the dam should be no less than 6 feet.
Geotextile
Geotextiles should be used as a separator between the graded stone, the soil base, and the abutments. The geotextile will prevent the migration of soil particles from the subgrade into the graded stone. The geotextile shall be specified in accordance with AASHTO M288-96 Section 7.5, Permanent Erosion Control Recommendations. The geotextile should be placed immediately adjacent to the subgrade without any voids and extend five feet beyond the downstream toe of the dam to prevent scour.
CONSTRUCTION SPECIFICATIONS
Mechanical or hand placement will be required to insure that the rock dam extends completely across the channel and securely ties into both channel banks. The center of the dam must be no less than six inches lower than the lowest side, to serve as a type of weir. Gabions can be installed to serve as rock filter dams, but should follow recommended sizing and installation specifications. Refer to specification Ga - Gabion.
6-117

MAINTENANCE
Rock dams should be removed once disturbed areas have been stabilized. Periodic inspection and required maintenance must be provided. Sediment shall be removed when it reaches a depth of one-half of the original height of the dam.
TO BE SHOWN ON THE EROSION AND SEDIMENT CONTROL PLAN
1. Figure 6-18.1, noting rock size as specified in Appendix C.

6-118

GaSWCC (Amended - 2000)

Geotextiles

6" Minimum
NOTE: Sediment Trap is to be cleaned out when volume becomes half full.

6' Minimum

Flow

3 - 5lb. stone

Geotextiles

NOTE: Rock size determined according to specifications set forth in Appendix C.

GaSWCC (Amended - 2000)

Figure 6-18.1

6-119

6-120

GaSWCC (Amended - 2000)

Retaining Wall

Re

DEFINITION
A wall constructed of one or more of the following: concrete masonry, reinforced concrete cribbing, treated timbers, steel pilings, gabions, stone drywall, rock riprap, etc.
PURPOSE
To assist in the stabilization of cut or fill slopes where stable slopes are not attainable without the use of the wall.
CONDITIONS
Use in conjunction with cut or fill slopes which, because of space limitations or unstable material, do not allow the stable slope criteria listed above, e.g. cuts into steep hillsides on small lots or cuts into hillsides behind shopping centers to provide loading space.
DESIGN CRITERIA
General
The design of a retaining wall is a complicated process. Many factors must be taken into account such as: stresses and forces outside and within the wall, allowable height, minimum thickness. Other considerations are: foundation design with respect to loadings, bearing values of soils, footing dimensions. Additional design factors are safety hazards, subsurface and surface drainage and appearance.
Each situation requires a specific design which is within the capabilities of the design engineer.

Consideration should be given to all of the alternative methods with regard to construction of the wall. Some methods are:
1. Concrete masonry 2. Concrete cribbing 3. Gabions 4. Steel piling 5. Stone drywall 6. Rock riprap, etc. 7. Treated timbers 8. Geotextile wrapped-face wall 9. Geotextile reinforced steep slopes

GaSWCC (Amended - 2000)

6-121

6-122

GaSWCC (Amended - 2000)

Retrofitting

Rt

DEFINITION
A device or structure placed in front of a permanent stormwater detention pond outlet structure to serve as a temporary sediment filter.
PURPOSE
This structure allows permanent stormwater detention basins to function as temporary sediment retention basins for land-disturbing projects.
CONDITIONS
This standard applies under the following conditions:
1. Shall not be used in detention basins on live streams or in basins with a total contributing drainage area of 100 acres or more.
2. Shall only be used in detention basins large enough to store 67 cubic yards of sediment per acre of disturbed area in the project.
3. Shall be considered a temporary structure and will be removed as soon as project is permanently stabilized. All accumulated sediment shall be removed, and the pond shall be brought to final grade (if possible), prior to the removal of the retrofit.
DESIGN CRITERIA
1. The height of the retrofit should be approximately one-half the height of the stormwater management outlet structure.
2. The pond must be capable of storing the required volume of sediment in addition to the required stormwater volume. The re-
GaSWCC (Amended - 2000)

quired sediment storage volume shall be achieved by either excavating the basin or raising the outlet structure's invert to achieve 67 cubic yards per acre of sediment storage. Remove sediment when one-third of the sediment storage capacity, not total pond capacity, is lost to sediment accumulation. This volume shall be marked on the riser or by setting a marked post near the riser.

3. For effective trapping efficiency, the sediment delivery inlets should be at the upper end of the basin.

4. For effective trapping efficiency, the lengthwidth ratio of the basin shall be at least 2:1. If the length-width ratio is not at least 2:1, the flow length shall be increased with the use of baffles installed within the basin.

CONSTRUCTION SPECIFICATIONS

The following types of structures are acceptable under the designated conditions:

Perforated Half-Round Pipe with Stone Filter Rt-P (See Figure 6-19.1)

a. Should be used only in detention ponds with less than 30 acre total drainage area.

b. Never to be used on exposed pipe end or winged headwall.

c. Diameter of half-round pipe should be 1.5 times the diameter of the principal pipe outlet or wider than the greatest width of the concrete weir.

d. Perforations and stone sizes are shown in Figure 6-19.1.

e. Shall be fixed by specified means (bolts, etc) to concrete outlet structure.

Slotted Board Dam with Stone (See Figure 6-19.3)

Rt-B

a. Can be used in detention ponds with drainage areas up to 100 acres.

b. Can be used with open end pipe outlets, winged headwalls, or concrete weir outlets.

c. Should be installed with minimum size 4x4 inch posts.

d. Boards should have 0.5-1.0 inch space between them.

6-123

e. Minimum size 3-4 inch stone filter shall be installed around the upstream side of the board dam.
All disturbed areas shall be vegetated immediately after construction with permanent vegetation. Refer to Ds3 and Ds4 - Disturbed Area Stabilization (With Permanent Vegetation) and Disturbed Area Stabilization (With Sodding) and Mb - Matting and Blankets.
MAINTENANCE
Retrofit structures shall be kept clear of trash and debris. This will require continuous monitoring and maintenance, which includes sediment removal when onethird of the sediment storage capacity has been lost. Structures are temporary and shall be removed when disturbed areas have been permanently stabilized.

TO BE SHOWN ON THE EROSION AND SEDIMENT CONTROL PLAN

Storage Calculations

1. Required stormwater storage = ______ cy (as determined by local ordinance)
2. Required sediment storage = ______ cy (67 cy/ac * ______ ac disturbed area)
3. Total required storage = _(1)_ + _(2)_ = _(3)_ cy 4. Available storage = _(4)_ cy 5. Is the available storage (4) greater than the total required storage (3)?
______ yes ______ no 6. If "no", the sediment storage capacity of the pond must be increased. Choose the method to be
used: ______ Raise the invert of the outlet structure ______ inches ______ Undercut the pond ______ feet ______ Other ____________________________________ 7. Clean-out elevation =______ft (Elevation corresponding to 22 cy/ac *_____ac disturbed area) 8. Is the length-width ratio 2:1 or greater? ______ yes ______ no 9. If "no", the length of flow must be increased. Choose the method to be used: ______ Baffles (Type of baffle: ___________ ) ______ Other _____________________________________

Note the CMP diameter and height if a half-round CMP retrofit is to be used.

Diameter =______inches

Height =______feet

6-124

GaSWCC (Amended - 2000)

One HalfRound corrugated metal pipe attached to weir box
Apron or Concrete Bottom to be used at the bottom of Half Round.

1" Holes 8"- 10" apart
Fill around barrier with 3"- 4" stone (even with top)

ISOMETRICS

L-2"x2"x1/4" Weir

Half Round perforated pipe during construction only
Flow

1/2"O Thrd. Rod w/nuts and washers (anc. to wall)

1'-0" Min. Graded Stone
PLAN
PERFORATED HALF-ROUND PIPE WITH STONE FILTER

GaSWCC (Amended - 2000)

Figure 6-19.1

6-125

Minimum 8' - 10' 50# - 150# Stone Rip-Rap

2'-0" Min.

STONE FILTER RING
Figure 6-19.2

4"x4" Post 2"x4"

0.5" - 1.0" spacing
6-126

Fill around barrier with 3" - 4" stone (even with top)
SLOTTED BOARD DAM WITH STONE FILTER
Figure 6-19.3
GaSWCC (Amended - 2000)

Sediment Barrier

Sd1

DEFINITION
Sediment barriers are temporary structures typically constructed of silt fence supported by steel or wood posts. Other types of barriers may include sandbags, straw bales, brush piles or other filtering material.
PURPOSE
To prevent sediment carried by sheet flow from leaving the site and entering natural drainage ways or storm drainage system by slowing storm water runoff and causing the deposition of sediment at the structure.
CONDITIONS
Barriers should be installed where runoff can be stored behind the barrier without damaging the fence or the submerged area behind the fence.
Silt fence shall not be installed across streams, ditches, waterways, or other concentrated flow areas.
DESIGN CRITERIA
HAY OR STRAW BALES
Hay or straw bales retain sediment load transported by sheet flow from disturbed areas. The bales' comparatively low flow rate should be considered when choosing the appropriate sediment barrier. Ponding above the bale can occur rapidly. The slope lengths contributing runoff to a bale barrier cannot exceed those listed in Table 6-20.1. Straw and hay bales shall not be used if the project duration is expected to exceed three months.

Table 6-20.1. Criteria For Straw or Hay Bale Placement

Land Slope
Percent
<2 2 to 5 5 to 10 10 to 20 >20

Maximum Slope Length Above Bale
Feet
75 50 35 20 10

SILT FENCE
Like hay or straw bales, silt fence is designed to retain sediment transported by sheet flow from disturbed areas. Silt fence performs the same function as hay or straw bales, allows a higher flow rate, and is usually faster and cheaper to install. Approved silt fence fabrics are listed in the Georgia Department of Transportation Qualified Products List #36 (QPL-36). See Table 6-20.5 for current Georgia DOT silt fence specifications.
Where all runoff is to be stored behind the fence (where no stormwater disposal system is present), maximum slope length behind a silt fence shall not exceed those shown in Table 6-20.2. The drainage area shall not exceed 1/4 acre for every 100 feet of silt fence.
Table 6-20.2. Criteria For Silt Fence Placement

Land Slope

Maximum Slope Length Above Fence

Percent

Feet

<2

100

2 to 5

75

5 to 10

50

10 to 20

25

>20*

15

*ln areas where the slope is greater than 20%, a flat area length of 10 feet between the toe of the slope to the fence should be provided.

Type A Silt Fence

Sd1-A

This 36-inch wide filter fabric shall be used on developments where the life of the project is greater than or equal to six months.

GaSWCC (Amended - 2000)

6-127

Type B Silt Fence

Sd1-B

Though only 22-inches wide, this filter fabric allows the same flow rate as Type A silt fence. Type B silt fence shall be limited to use on minor projects, such as residential home sites or small commercial developments where permanent stabilization will be achieved in less than six months.

Type C Silt Fence

Sd1-C

Type C fence is 36-inches wide with wire reinforcement.The wire reinforcement is necessary because this fabric allows almost three times the flow rate as Type A silt fence. Type C silt fence shall be used where runoff flows or velocities are particularly high or where slopes exceed a vertical height of 10 feet.

Provide a riprap splash pad or other outlet protection device for any point where flow may top the sediment fence. Ensure that the maximum height of the fence at a protected, reinforced outlet does not exceed 1 ft. and that support post spacing does not exceed 4 ft.

CONSTRUCTION SPECIFICATIONS

Sandbags

Sd1-S

(if approved by local issuing authority)

Should be installed so that flow under or between bags is minimal. Anchoring with steel rods may be required if structure height exceeds two bags.

Hay or Straw Bales

Sd1-Hb

(if approved by local issuing authority)

Bales will be placed in a single row, lengthwise, on the contour and embedded in the soil to a depth of 4 inches. Bales must be securely anchored in place by stakes or bars driven through the bales or by other acceptable means to prevent displacement. See Figures 6-20.1 and 6-20.2 for installation requirements.

Brush Barrier

Sd1-Bb

(only during timber clearing operations)

Brush obtained from clearing and grubbing operations may be piled in a row along the perimeter of disturbance at the time of clearing and grubbing. Brush barriers should not be used in developed areas or locations where aesthetics are a concern.

Brush should be wind-rowed on the contour as nearly as possible and may require compaction. Construction equipment may be utilized to satisfy this requirement.

6-128

The minimum base width of the brush barrier shall be 5 feet and should be no wider than 10 feet. The height of the brush barrier should be between 3 and 5 feet.
If a greater filtering capacity is required, a commercially available filter fabric may be placed on the side of the brush barrier receiving the sediment-laden runoff. The lower edge of the fabric must be buried in a 6-inch deep trench immediately uphill from the barrier. The upper edge must be stapled, tied or otherwise fastened to the brush barrier. Edges of adjacent fabric pieces must overlap each other. See Figure 6-20.3.
Silt Fence
The manufacturer shall have either an approved color mark yarn in the fabric or label the fabricated silt fence with both the manufacturer and fabric name every 100 feet.
The temporary silt fence shall be installed according to this specification, as shown on the plans or as directed by the engineer. For installation of the fabric, see Figures 6-20.4, 6-20.5, and 6-20.6 respectively.
Post installation shall start at the center of the lowpoint (if applicable) with remaining posts spaced 6 feet apart for Type A and B silt fences and 4 feet apart for Type C silt fence. While Type A and B silt fences can be used with both wood and steel posts, only steel posts shall be used with Type C silt fence. For post size requirements, see Table 6-20.3. Fasteners for wood posts are listed in Table 6-20.4.
Along stream buffers and other sensitive areas, two rows of Type C silt fence or one row of Type C silt fence backed by haybales shall be used.
MAINTENANCE
Sediment shall be removed once it has accumulated to one-half the original height of the barrier. Filter fabric shall be replaced whenever it has deteriorated to such an extent that the effectiveness of the fabric is reduced (approximately six months). Temporary sediment barriers shall remain in place until disturbed areas have been permanently stabilized. All sediment accumulated at the barrier shall be removed and properly disposed of before the barrier is removed.
GaSWCC (Amended - 2000)

A

A

B

Points A should be higher than point B
PROPER PLACEMENT OF STRAW BALE BARRIER IN DRAINAGE WAY

Binding Wire or Twine
Filtered Runoff

Staked and Entrenched Straw Bale
Compacted Soil to Prevent Piping
Sediment Laden Runoff

Note: Embed hay bales a minimum of 4 inches.
CROSS-SECTION OF A PROPERLY INSTALLED STRAW BALE

GaSWCC (Amended - 2000)

Figure 6-20.1

6-129

Flow
4" Vertical Face
EMBEDDING DETAIL

Angle first stake towards previously laid bale

Flow

Wire or nylon bound bales placed on the contour
2 re-bars, steel pickets, or 2" x 2" stakes 1 1/2' to 2' in ground

ANCHORING DETAIL

NOTE:
- Anchor and embed into soil to prevent washout or water working under barrier - Repair or replacement must be made promptly as needed

STAKED HAYBALE BARRIERS

6-130

Figure 6-20.2

GaSWCC (Amended - 2000)

BRUSH BARRIER DETAILS

FILL SLOPE

VAR.

SOME OF THE HEAVIER MATERIALS REQUIRED AT THE TOP

VARIES 3' TO 5'

SECTION
NOTE: INTERMINGLE BRUSH, LOGS, ETC., SO AS NOT TO FORM A SOLID DAM.

VARIES 5' TO 10'

GROUND LINE

VARIES 3' TO 5'

FRONT VIEW

Figure 6-20.3

GaSWCC (Amended - 2000)

6-131

Table 6-20.3. Post Size

Type A

Minimum Length 4'

Type B

3'

Type C

4'

Type of Post
Soft wood Oak Steel
Soft wood Oak Steel
Steel

Size of Post
3" dia. or 2x4 1.5" x 1.5"
1.3lb./ft. min.
2" dia. or 2x2 1" x 1"
.75lb./ft. min.
1.3lb./ft. min.

Table 6-20.4. Fasteners For Wood Posts

Wire Staples Nails

Gauge 17 min. Gauge 14 min.

Crown 3/4" wide Length
1"

Legs 1/2" long Button Heads
3/4"

Staples/Post 5 min.
Nail/Post 4 min.

Note: Filter fabric may also be attached to the post by wire, cord, and pockets.

6-132

GaSWCC (Amended - 2000)

2.5' min. 4' min.

1.5' min.

2.5' min.

28"

Flow 6" 2"
SIDE VIEW
6' max. o.c.
Fabric
6" Trench
FRONT VIEW
NOTE: Use 36" D.O.T. approved fabric. Use wood or steel posts
SILT FENCE - TYPE A

1.5' min.

GaSWCC (Amended - 2000)

Figure 6-20.4

28"

6-133

18" min.

6-134

18" min.

18" min.

18" min.

16"

Flow 4" 2"
SIDE VIEW
6' max. o.c.
Fabric 4"
Trench
FRONT VIEW
NOTE: Use 22" D.O.T. approved fabric. Use wood or steel posts
SILT FENCE - TYPE B
Figure 6-20.5

16"

GaSWCC (Amended - 2000)

30" min.

28"

Flow

6"

18" min.

2" SIDE VIEW 4' max o.c.
Fabric
( ) Woven Wire Fence Backing

30" min.

28"

18" min.

6" Trench

FRONT VIEW
NOTE: Use 36" D.O.T. approved fabric. Use steel posts.- only
SILT FENCE - TYPE C

GaSWCC (Amended - 2000)

Figure 6-20.6

6-135

Flow

End of fabric fence

Beginning of fabric fence

18"

Flow

Post

6' o.c. max.

TOP VIEW - (Not to scale)

OVERLAP AT FABRIC ENDS

Wood Post with Staple Placement

Wood Post with Nail Placement

6-136

FRONT VIEWS

FASTENERS FOR SILT FENCES
Figure 6-20.7

GaSWCC (Amended - 2000)

Table 6-20.5

TYPE FENCE

A

B

C

Tensile Strength (Lbs. Min.) (1) (ASTM D-4632)

Warp - 120 Fill - 100

Warp - 120 Fill - 100

Warp - 260 Fill - 180

Elongation (% Max.) (ASTM D-4632)

40

40

40

AOS (Apparent Opening Size)

(Max. Sieve Size) (ASTM D-4751)

#30

#30

#30

Flow Rate (Gal/Min/Sq. Ft.) (GDT-87)

25

25

70

Ultraviolet Stability (2)

(ASTM D-4632 after 300 hours

weathering in accordance with

80

80

80

ASTM D-4355)

Bursting Strength (PSI Min.)

(ASTM D-3786 Diaphragm Bursting 175

175

175

Strength Tester)

Minimum Fabric Width (Inches)

36

22

36

(1) Minimum roll average of five specimens. (2) Percent of required initial minimum tensile strength.

GaSWCC (Amended - 2000)

6-137

6-138

GaSWCC (Amended - 2000)

Inlet Sediment Trap

Sd2

DEFINITION
A temporary protective device formed around a storm drain drop inlet to trap sediment.
PURPOSE
To prevent sediment from leaving the site, or from entering storm drainage systems, prior to permanent stabilization of the disturbed area.
CONDITIONS
Sediment traps should be installed at or around all storm drain drop inlets that receive runoff from disturbed areas.
DESIGN CRITERIA
Many sediment filtering devices can be designed to serve as temporary sediment traps. Sediment traps must be self-draining unless they are otherwise protected in an approved fashion that will not present a safety hazard. The drainage area entering the inlet sediment trap shall be no greater than one acre.
If runoff may bypass the protected inlet, a temporary dike should be constructed on the down slope side of the structure. Also, a stone filter ring may be used on the up slope side of the inlet to slow runoff and filter larger soil particles. Refer to Fr - Stone Filter Ring.
Excavated Inlet Sediment Trap
An excavation may be created around the inlet sediment trap to provide additional sediment storage. The trap shall be sized to provide a minimum storage capacity calculated at the rate of 67 cubic yards per acre of drainage area. A minimum depth of 1.5 feet for sediment storage should be provided. Side slopes shall not be steeper than 2:1.
GaSWCC (Amended - 2000)

CONSTRUCTION SPECIFICATIONS

Sediment traps may be constructed on natural ground surface, on an excavated surface, or on machine compacted fill provided they have a non-erodible outlet.

Filter Fabric with Supporting Frame Sd2-F

This method of inlet protection is applicable where the inlet drains a relatively flat area (slope no greater than 5%) and shall not apply to inlets receiving concentrated flows, such as in street or highway medians. As shown in Figure 6-21.1, Type C silt fence supported by steel posts shall be used. The stakes shall be spaced evenly around the perimeter of the inlet a maximum of 3 feet apart, and securely driven into the ground, approximately 18 inches deep. The fabric shall be entrenched 12 inches and backfilled with crushed stone or compacted soil. Fabric and wire shall be securely fastened to the posts, and fabric ends must be overlapped a minimum of 18 inches or wrapped together around a post to provide a continuous fabric barrier around the inlet.

Baffle Box

Sd2-B

For inlets receiving runoff with a higher volume or velocity, a baffle box inlet sediment trap should be used. As shown in Figure 6-21.2, the baffle box shall be constructed of 2" x 4" boards spaced a maximum of 1 inch apart or of plywood with weep holes 2 inches in diameter. The weep holes shall be placed approximately 6 inches on center vertically and horizontally. Gravel shall be placed outside the box, all around the inlet, to a depth of 2 to 4 inches. The entire box is wrapped in Type C filter fabric that shall be entrenched 12 inches and backfilled.

Block and Gravel Drop Inlet Protection Sd2-Bg

This method of inlet protection is applicable where heavy flows are expected and where an overflow capacity is necessary to prevent excessive ponding around the structure. As shown in Figure 6-21.3, one block is placed on each side of the structure on its side in the bottom row to allow pool drainage. The foundation should be excavated at least 2 inches below the crest of the storm drain.The bottom row of blocks are placed against the edge of the storm drain for lateral support and to avoid washouts when overflow occurs. If needed, lateral support may be given to subsequent rows by placing 2" x 4" wood studs through block openings. Hardware cloth or comparable wire mesh with 1/2 inch openings shall be fitted over all block openings to hold gravel in place. Clean gravel should be placed 2 inches below the top of the block on a 2:1 slope or flatter and smoothed to an even grade. DOT #57 washed stone is recommended.
6-139

Gravel Drop Inlet Protection Sd2-G

This method of inlet protection is applicable where heavy concentrated flows are expected. As shown in Figure 6-21.4, stone and gravel are used to trap sediment. The slope toward the inlet shall be no steeper than 3:1. A minimum 1 foot wide level stone area shall be left between the structure and around the inlet to prevent gravel from entering the inlet. On the slope toward the inlet, stone 3 inches in diameter and larger should be used. On the slope away from the inlet, 1/2 to 3/4 inch gravel (#57 washed stone) should be used at a minimum thickness of 1 foot.

Sod Inlet Protection

Sd2-S

This method of inlet protection is applicable only at the time of permanent seeding, to protect the inlet from sediment and mulch material until permanent vegetation has become established. As shown in Figure 6-21.6, the sod shall be placed to form a turf mat covering the soil for a distance of 4 feet from each side of the inlet structure. Sod strips shall be staggered so that adjacent strip ends are not aligned.

Excavated Inlet Sediment Trap

The sediment trap shall be placed immediately around the inlet. The excavation shall be constructed immediately outside of the sediment trap and provide a minimum depth of 1.5 feet for sediment storage.

Curb Inlet Protection Sd2-P

Once pavement has been installed, a curb inlet filter shall be installed on inlets receiving runoff from disturbed areas. This method of inlet protection shall be removed if a safety hazard is created.

One method of curb inlet protection uses "pigs-in-ablanket" - 8-inch concrete blocks wrapped in filter fabric. See Figure 6-21.5. Another method uses gravel bags constructed by wrapping DOT #57 stone with filter fabric, wire, plastic mesh, or equivalent material.

A gap of approximately 4 inches shall be left between the inlet filter and the inlet to allow for overflow and prevent hazardous ponding in the roadway. Proper installation and maintenance are crucial due to possible ponding in the roadway, resulting in a hazardous condition.

Several other methods are available to prevent the entry of sediment into storm drain inlets. Figure 6-21.7 shows of one of these alternative methods.

MAINTENANCE
The trap shall be inspected daily and after each rain and repairs made as needed.
Sediment shall be removed when the sediment has accumulated to one-half the height of the trap. Sediment shall be removed from curb inlet protection immediately. For excavated inlet sediment traps, sediment shall be removed when one-half of the sediment storage capacity has been lost to sediment accumulation. Sod inlet protection shall be maintained as specified in Ds4 - Disturbed Area Stabilization (With Sodding).
Sediment shall not be washed into the inlet. It shall be removed from the sediment trap and disposed of and stabilized so that it will not enter the inlet, again.
When the contributing drainage area has been permanently stabilized, all materials and any sediment shall be removed, and either salvaged or disposed of properly. The disturbed area shall be brought to proper grade, then smoothed and compacted. Appropriately stabilize all disturbed areas around the inlet.

6-140

GaSWCC (Amended - 2000)

2 x 4 Steel frame
1.5' max
3' min

Wire-backing

Drop inlet with grate
Frame

Stake Fabric
Buried fabric
1' min

Gather excess at corners

Figure 6-21.1 - Fabric and Supporting Frame For Inlet Projection

GaSWCC (Amended - 2000)

6-141

2" Weep Holes See Note 4
Inlet

2" - 4" Gravel
2" Weep Holes (typ.)

PLAN

2" - 4" 3' - 4'

Post
Inlet
SIDE
BAFFLE BOX

2 x 4 or 4 x4 Posts
Interior Bracing Silt fence material attached to all sides
Silt fence material Ground
Pipe

6-142

Figure 6-21.2

GaSWCC (Amended - 2000)

Dewatering Concrete block

2:1 slope, gravel filter

Temporary sediment pool

Wire screen

Dewatering

1' min 2' max
Sediment

16"
Drop inlet with grate

Figure 6-21.3 - Block and Gravel Drop Inlet Protection

Temporary sediment pool

1' min 2' max

2:1 slope

Fine gravel face (1' min thinkness)

3" - 6" stone

3:1 slope 1'

Wire mesh (optional)

Figure 6-21.4 - Gravel Drop Inlet Protection (Gravel Donut)

GaSWCC (Amended - 2000)

6-143

6-144

B

Catch Basin

Curbing

FLOW

FLOW

Pavement

B

Pavement Flow Gutter

8" Concrete Block wrapped in Filter Fabric.
Catch Basin

SECTION B-B

NOTE: Install filter after any asphalt pavement installation.
CURB INLET FILTER
"PIGS IN BLANKET"

Figure 6-21.5

GaSWCC (Amended - 2000)

4' 4'
Four 1 ft wide strips of sod on each side of the drop inlet Figure 6-21.6 - Sod Strips Protect Inlet Area From Erosion (source: Va SWCC)

Figure 6-21.7 - Alternative Inlet Sediment Trap
GaSWCC (Amended - 2000)

6-145

TO BE SHOWN ON THE EROSION AND SEDIMENT CONTROL PLAN
If the EXCAVATED INLET SEDIMENT TRAP is used, show the following information:
1. Drainage area = _______ ac 2. Required sediment storage = 67 cy/ac * drainage area
Required sediment storage = 67 cy/ac * _____ ac Required sediment storage = ______ cy = _______ cf 3. Assume excavation depth (minimum of 1.5 ft.) = ______ ft 4. Assume slope of sides (shall not be steeper than 2:1) = __ :1 5. Determine required surface area SAmin = Required sediment storage / excavation depth SAmin = ______ cy / ______ ft SAmin = ______ sf 6. Assume shape of excavation and determine dimensions. (A rectangular shape with 2:1 length to width ratio is recommended.) Shape: _______ Dimensions: l = _____ ft w = _____ ft diameter (if applicable) = ______ ft
Provide a detail showing the depth, length and width, or diameter (if applicable), and side slopes of the excavation.

6-146

GaSWCC (Amended - 2000)

Temporary Sediment

Basin

Sd3

DEFINITION
A basin created by the construction of a barrier or dam across a concentrated flow area or by excavating a basin or by a combination of both. A sediment basin typically consists of a dam, a pipe outlet, and an emergency spillway.The size of the structure will depend upon the location, size of the drainage area, soil type, and rainfall pattern.
PURPOSE
To detain runoff waters and trap sediment from erodible areas in order to protect properties and drainage ways below the installation from damage by excessive sedimentation and debris. The water is temporarily stored and the bulk of the sediment carried by the water drops out and is retained in the basin while the water is automatically released.
CONDITIONS
This practice applies to critical areas where physical site conditions, construction schedules, or other restrictions preclude the installation or establishment of erosion control practices to satisfactorily reduce runoff, erosion, and sedimentation. The structure may be used in combination with other practices and should remain in effect until the sediment-producing area is permanently stabilized.
This standard applies to the installation of temporary (to be removed within 18 months) sediment basins on sites where: (1) failure of the structure would not result in loss of life or interruption of use or service of public utilities, and (2) the drainage area does not exceed 150 acres.
GaSWCC (Amended - 2000)

DESIGN CRITERIA
Compliance With Laws and Regulations
Design and construction shall comply with state and local laws, ordinances, rules and regulations. Basins shall be constructed according to the approved erosion and sediment control plan unless modified by the design engineer.
Location
Sediment basins shall never be placed in live streams. They should be located so that storm drains discharge into the basin. The sediment basin should be located to obtain the maximum storage benefit from the terrain and for ease of clean-out of the trapped sediment. It should be located to minimize interference with construction activities and construction of utilities.
Volume
The sediment storage volume of the basin, as measured to the elevation of the crest of the principal spillway, shall be at least 67 cubic yards per acre for the disturbed area draining into the basin (67 cubic yards is equivalent to 1/2 inch of sediment per acre of drainage area). The entire drainage basin area should be used for this computation, rather than the disturbed area alone, to help ensure adequate trapping efficiency. Sediment shall be removed from the basin when approximately one-third of the storage volume has been lost to sediment accumulation. This volume shall be marked on the riser or by setting a marked post near the riser.
Surface Area
Studies (Barfield and Clar, 1985) indicate that the following relationship between surface area and peak inflow rate gives a trapping efficiency from greater than 75% for clay loam to 95% for loamy sandy soils.
A = 0.01q
where A is basin surface area in acres and q is peak inflow rate in cfs. Area is measured at the crest of the principal spillway riser. The minimum peak inflow rate is determined from a 2-year, 24-hour storm.
6-147

Shape
It is recommended that the designer of a sediment basin incorporate features to maximize detention time within the basin. Suggested methods of accomplishing this objective are:
1. Length to width ratio greater than 2:1, where length is the distance between the inlet and outlet.
2. A wedge shape with the inlet located at the narrow end.
3. Installation of baffles or diversions.
Procedure for Determining or Altering Sediment Basin Shape
As specified in the Standard and Specification, the pool area at the elevation of crest of the principal spillway shall have a length to width ratio of at least 2:1. The purpose of this requirement is to minimize the "shortcircuiting" effect of the sediment-laden inflow to the riser and thereby increasing the effectiveness of the sediment basin. The purpose of this procedure is to prescribe the parameters, procedures and methods of determining and modifying the shape of basin.
The length of the flow path (L) is the distance from the point of inflow to the riser (outflow point). The point of inflow is the point that the stream enters the normal pool (pool level at the riser crest elevation). The pool area (A) is the area of the normal pool. The effective width (We) is equal to the Area (A) divided by the length (L). The length to width ratio (L:W) is found by the equation:
L:W= I/We where We = A/L
In the event there is more than one inflow point, any inflow point which conveys more than 30 percent of the total peak inflow rate shall meet the length-width ratio criteria.
The required basin shape may be obtained by proper site selection, by excavation, or by constructing a baffle in the basin. The purpose of the baffle is to increase the effective flow length from the inflow point to the riser. Baffles shall be placed mid-way between the inflow point and the riser. The baffle length shall be as required to provide the minimum 2:1 length-width ratio. The effective length (Le) shall be the shortest distance the water must flow from the inflow point around the end of the baffle to the outflow point. Then:
L:W = Le/We where We = A/Le
6-148

Three examples are shown on the following pages. Note that for the special case in example C the water is allowed to go around both ends of the baffle and the effective length, Le = L1a + L1b = L2a + L2d. Otherwise, the length-width ratio computations are the same as shown above. This special case procedure for computing Le is allowable only when the two flow paths are equal, i.e., when L1 = L2. A baffle detail is also shown. For examples of sediment basin baffles, refer to Figure 6-22.2.
The dimensions necessary to obtain the required basin volume and surface area shall be clearly shown on the plans to facilitate plan review, construction and inspection.
Spillways
Runoff may be computed by the method outlined in Appendix A. Other approved equivalent methods may be used. Runoff computations shall be based upon the worst soil-cover conditions expected to prevail in the contributing drainage area during the anticipated effective life of the structure. The combined capacities of the principal and emergency spillway shall be sufficient to pass the peak rate of runoff from a 25-year, 24-hour frequency storm. Even if the principal spillway is designed to convey the peak rate of runoff from a 25-year, 24-hour storm, an emergency spillway shall be present.
1. Principal spillway - A spillway consisting of a vertical pipe or box type riser joined (watertight connection) to a pipe which shall extend through the embankment and outlet beyond the downstream toe of the fill shall be provided. See figure 6-22.3. The metal gauge thickness shall comply with DOT or NRCS specifications. The discharge shall be based on a 2-year, 24-hour storm for the total drainage area without causing flow through the emergency spillway. The appropriate disturbed soil cover condition shall be used. The minimum size of the pipe shall be 8 inches in diameter. Principal spillway capacities may be determined from Table 6-22.1. Weir flow discharge above the crest of the riser may be determined from Table 6-22.2. Principal spillway pipe, riser pipe, and trash rack proportions are shown in Table 6-22.2.
a. Crest elevation - The crest elevation of the riser shall be a minimum of one foot below the elevation of the control section of the emergency spillway.
b. Watertight barrel assembly - The riser and all pipe connections shall be completely water tight except for the inlet opening at the top or dewatering openings, and shall not have any other holes, leaks, rips or perforations.
GaSWCC (Amended - 2000)

c. Dewatering the basin - Retention time within the basin is an important factor in effective sediment retention. The method used to dewater the sediment basin may be selected from the following two methods:
Perforated Riser Pipe - The perforated riser pipe is the conventional method for dewatering a sediment basin. The lower half of the riser is perforated with 1/2inch holes spaced approximately 3-inches apart. It is covered with two feet of 3 to 4 inch stone.
Skimmer Outlet - The skimmer-type dewatering device operates at the surface of the ponded water and will not withdraw sediment from the submerged volume of the basin. As compared to conventional perforated risers, skimmers discharge a 45 percent less mass of sediment. However, skimmers are mechanically more complex and will require frequent inspection and maintenance in order to operate as designed. See Figure 622.4.
d. Trash rack and anti-vortex device - A trash rack and anti-vortex device shall be securely installed on top of the riser and may be the type as shown in Figure 6-22.5.
e. Base - The riser shall have a base attached with a watertight connection and shall have sufficient weight to prevent flotation of the riser. A concrete base 18" thick with the riser embedded 9-inches in the base is recommended. Computations shall be made to design a base which will prevent flotation. See Figure 6-22.6 and Table 6-22.3 for details.
f. Anti-Seep Collars - One anti-seep collar shall be installed around the pipe, near the center of the dam, when any of the following conditions exist:
1. The settled height of the dam is greater than 15 feet.
2. The conduit is smooth pipe larger than 8" in diameter.
3. The conduit is corrugated metal pipe larger than 12" in diameter.
Use an anti-seep collar with an 18-inch projection for heads (H) less than or equal to 10 feet and a 24-inch projection for heads (H) greater than 10 feet. The anti-seep collar and its connection shall be watertight.
g. Outlet - An outlet shall be provided, including a means of conveying the discharge in an erosion-free manner to an existing stable area. Where discharge occurs at the property line, drainage easements will be obtained in ac-
GaSWCC (Amended - 2000)

cordance with local ordinances. Adequate notes and references will be shown on the erosion and sediment control plan. Protection against scour at the discharge end of the pipe spillway shall be provided. Measures may include excavated plunge pools, riprap, impact basins, revetments, or other approved methods. Refer to specification St - Storm Drain Outlet Protection.
h. For typical features of a temporary sediment basin, see Figure 6-22.1.
2. Emergency Spillway - The entire flow area of the emergency spillway shall be constructed in undisturbed ground (not fill). The emergency spillway cross-section shall be trapezoidal with a minimum bottom width of eight feet. This spillway channel shall have a straight control section of at least 20 feet in length and a straight outlet section for a minimum distance equal to 25 feet. See Figure 6-22.7.
a. Capacity - The minimum capacity of the emergency spillway shall be that required to pass the peak rate of runoff from the 25-year, 24hour frequency storm, less any reduction due to flow in the principal spillway. The appropriate disturbed soil cover condition shall be used. Emergency spillway dimensions may be determined by using the method described in this section. Refer to Table 6-22.4 and Figure 6-22.7.
b. Velocities - The velocity of flow in the exit channel shall not exceed 5 feet per second for vegetated channels. For channels with erosion protection other than vegetation, velocities shall be within the non-erosive range for the type of protection used. Vegetation, riprap, asphalt or concrete shall be provided to prevent erosion. Refer to specification Ch - Channel Stabilization.
c. Freeboard - Freeboard is the difference between the design high water elevation in the emergency spillway and the top of the settled embankment. The freeboard shall be at least one foot.
Entrance of Runoff Into Basin
Points of entrance of surface runoff into excavated sediment basins shall be protected to prevent erosion and sediment generation. Dikes, swales or other water control devices shall be installed as necessary to direct runoff into the basin. Points of runoff entry should be located as far away from the riser as possible, to maximize travel time. Refer to St - Storm Drain Outlet Protection.
6-149

CONSTRUCTION SPECIFICATIONS
Site Preparation
Areas under the embankment and under structural works shall be cleared, grubbed, and stripped of topsoil. All trees, vegetation, roots and other objectionable material shall be removed and disposed of by approved methods. In order to facilitate clean-out or restoration, the pool area (measured at the top of the pipe spillway) will be cleared of all brush and trees.
Cut-off Trench
A cut-off trench will be excavated along the centerline of earth fill embankments. The minimum depth shall be 2 feet. The cut-off trench shall extend up both abutments to the riser crest elevation. The minimum bottom width shall be 4 feet, but wide enough to permit operation of compaction equipment. The side slopes shall be no steeper than 1:1. Compaction requirements shall be the same as those for the embankment. The trench shall be drained during the backfilling and compaction operations.
Embankment
The fill material shall be taken from approved areas shown on the plans. It shall be clean mineral soil free of roots, woody vegetation, oversized stones, rocks or other objectionable material. Relatively pervious materials such as sand or gravel (Unified Soil Classes GW, GP, SW & SP) shall be placed in the downstream section of the embankment. Areas on which fills are to be placed shall be scarified prior to placement of fill. The fill material shall contain sufficient moisture so that it can be formed by hand into a ball without crumbling. If water can be squeezed out of the ball, it is too wet for proper compaction. Fill material shall be placed in sixinch to eight-inch thick continuous layers over the entire length of the fill. Compaction shall be obtained by routing and hauling the construction equipment over the fill so that the entire surface of the fill is traversed by at least one wheel or tread track of the equipment or by the use of a compactor. The embankment shall be constructed to an elevation 5 percent higher than the design height to allow for settlement.
Principal Spillway
The riser shall be securely attached to the pipe or pipe stub by welding the full circumference making a watertight structural connection.The pipe stub must be attached to the riser at the same percent (angle) of grade as the outlet conduit. The connection between the riser

and the riser base shall be watertight. All connections between pipe sections must be achieved by approved watertight band assemblies. The pipe and riser shall be placed on a firm, smooth foundation of impervious soil as the embankment is constructed. Breaching the embankment is unacceptable. Pervious materials such as sand, gravel, or crushed stone shall not be used as backfill around the pipe or anti-seep collar. The fill material around the pipe spillway shall be placed in four inch layers and compacted under and around the pipe to at least the same density as the adjacent embankment. Care must be taken not to raise the pipe from firm contact with its foundation when compacting under the pipe haunches. A minimum depth of two feet of hand compacted backfill shall be placed over the pipe spillway before crossing it with construction equipment.
Emergency Spillway
The emergency spillway shall be installed in undisturbed ground. The achievement of planned elevations, grades, design width, entrance and exit channel slopes are critical to the successful operation of the emergency spillway and must be constructed within a tolerance of 0.2 feet. If the emergency spillway requires erosion protection other than vegetation, the lining shall not compromise the capacity of the emergency spillway, e.g. the emergency spillway shall be over-excavated so that the lining will be flush with the slope surface.
Vegetative Treatment
Stabilize the embankment and all other disturbed areas in accordance with the appropriate permanent vegetative measure, Ds3, immediately following construction. In no case shall the embankment remain unstabilized for more than seven (7) days. Refer to specifications Ds2, Ds3, and Ds4 - Disturbed Area Stabilization (Temporary Seeding, Permanent Vegetation, and Sodding) respectively.
Erosion and Pollution Control
Construction operations will be carried out in such a manner that erosion and water pollution will be minimized. State and local law concerning pollution abatement shall be complied with.
Safety
State and local requirements shall be met concerning fencing and signs warning the public of hazards of soft sediment and floodwater.

6-150

GaSWCC (Amended - 2000)

MAINTENANCE
Repair all damages caused by soil erosion or construction equipment at or before the end of each working day.
Sediment shall be removed from the basin when it reaches the specified distance below the top of the riser. Sediment shall not enter adjacent streams or drainageways during sediment removal or disposal. The sediment shall not be deposited downstream from the embankment, adjacent to a stream or floodplain.
FINAL DISPOSAL
When temporary structures have served their intended purpose and the contributing drainage area has been properly stabilized, the embankment and resulting sediment deposits are to be leveled or otherwise disposed of in accordance with approved sediment control plan. The proposed use of a sediment basin site will often dictate final disposition of the basin and any sediment contained therein. If the site is scheduled for future construction, then the embankment and trapped sediment must be removed, safely disposed of, and backfilled with a structural fill. When the basin area is to remain open space, the pond may be pumped dry, graded and backfilled.
TO BE SUBMITTED WITH/ON THE EROSION AND SEDIMENT CONTROL PLAN
On the E&SC Plan
1. The specific location of the basin, showing existing and proposed contours.
2. Maintenance equipment access points.
3. Completed Figures 6-22.8 and 6-22.9. (details for the cross section of dam, principal spillway, and emergency spillway, and profile of emergency spillway).
4. Details of trash rack, concrete riser base, and outlet structure assembly. (Refer to Figures 6-22.4 to 622.7.)
On 8 1/2" x 11"Sheet(s)
1. Hydrological study, including information regarding stage/storage relationship.
2. Temporary sediment basin design sheet, p. 6-168 to 6-170.
3. Completed Figures 6-22.8 and 6-22.9 (details for the cross section of the dam, principal spillway, and emergency spillway, and profile of emergency spillway).

GaSWCC (Amended - 2000)

6-151

6-152

GaSWCC (Amended - 2000)

Riser pipe for principal spillway

Trash rack

1/2" drainage holes with gravel 3" - 4" stone

Flood pool 1' min.

Anti-flotation block

Selected fill placed in layers and compacted

1:1
Principal spillway pipe

Emergency spillway crest

Freeboard - 1' min.
2.5:1 or flatter
Embankment stabilized with vegetation

Anti-seep collar
Cut-off trench 2' deep, min.

Stabilized outlet

CROSS SECTION

Fill Height
less than 10 ft 10 feet to 15 ft

Minimum Top Width
8.0 ft 10.0 ft

NOTES:
1. The emergency spillway shall be installed in undisturbed ground.
2. The emergency spillway must be constructed within a tolerance of 0.2 feet.

EMERGENCY SPILLWAY

SEDIMENT BASIN

TOP OF EMBANKMENT
RISER WITH TRASH RACK

Principal Spillway
Rock Rip-Rap Outlet

PLAN VIEW
Figure 6-22.1 - Basic Components of a Temporary Sediment Basin
GaSWCC (Amended - 2000)

6-153

SEDIMENT BASIN BAFFLES Examples: Plan Views - not to scale

A.

Inflow

L
Le= L Le = Total distance from the
point of inflow around the baffle to the riser

Riser (outlet)

B. Inflow
Le = L1 + L2

D D/2
L1

Baffle L 2
d/2

d

Normal pool

Riser

6-154

Figure 6-22.2 (Sheet 1 of 2)

GaSWCC (Amended - 2000)

Normal Pool C.
Le = L1 + L2

d/2 d

L2 Baffle
L1

Riser
D D/2

D.

Normal Pool

Riser

Inflow

L1b

L2b

Baffle

L1a

L2a

d d/2

Le= L1a+L1b= L2a + L 2b

Inflow

4' x 8' x 1/2" exterior plywood or equivalent

Ground line
3'

4' 8' o/c

6" Riser crest elevation
Posts - 4" square or 5" round minimum.

GaSWCC (Amended - 2000)

Figure 6-22.2 (Sheet 2)

6-155

Vs

Vc

T
A Emergency Spillway Crest

Zu

Zd

Antiseep Collar

B

C

E L

PRINCIPAL SPILLWAY DESIGN

T = Top width of dam, ft. Zu = Upstream side slope Zd = Downstream side slope

A = Top of dam elevation B = Lowest elevation of pipe at riser C = Lowest elevation of pipe at outlet E = Extended length of pipe beyond toe of dam L = Total length of pipe, ft. L = [ A - (B + C) /2 ] [ Zu + Zd ] + T + E

Figure 6-22.3

6-156

GaSWCC (Amended - 2000)

Table 6-22.1. Pipe Flow Chart For Corrugated Metal Pipe Drop Inlet Principal Spillway Conduit

For Corrugated Metal Pipe Inlet K = K + K = 1.0 and 70 Feet of

m

a

b

Corrugated Metal Conduit (full flow assumed), n = 0.025

(Note correction factors for pipe lengths other than 70 feet)

Diameter Of Pipe In Inches

H, in feet

8"

12"

18"

24"

30"

36"

42"

48"

Discharge In Cubic Feet Per Second

3

1.22

3.43

9.48

19.1

32.6

49.9

71.2

96.5

4

1.40

3.97

10.9

22.1

37.6

57.7

82.3

111

5

1.57

4.43

12.2

24.7

42.1

64.5

92.0

125

6

1.72

4.86

13.4

27.0

46.1

70.6

101

136

7

1.86

5.25

14.5

29.2

49.8

76.3

109

147

8

1.99

5.61

15.5

31.2

53.2

81.5

116

158

9

2.11

5.95

16.4

33.1

56.4

86.5

123

167

10

2.22

6.27

17.3

34.9

59.5

91.2

130

176

11

2.33

6.58

18.2

36.6

62.4

95.6

136

185

12

2.43

6.87

19.0

38.2

65.2

99.9

142

193

13

2.53

7.15

19.7

39.8

67.8

104

148

201

14

2.63

7.42

20.5

41.3

70.4

108

154

208

15

2.72

7.68

21.2

42.8

72.8

112

159

216

16

2.81

7.93

21.9

44.2

75.2

115

165

223

17

2.90

8.18

22.6

45.5

77.5

119

170

230

18

2.98

8.41

23.2

46.8

79.8

120

174

236

19

3.06

8.64

23.9

48.1

82.0

126

179

243

20

3.14

8.87

24.5

49.4

84.1

129

184

249

L, in feet

Correction Factors For Other Pipe Lengths

30

1.41

1.36

1.29

1.24

1.21

1.18

1.15

1.13

40

1.27

1.23

1.20

1.17

1.14

1.12

1.11

1.10

50

1.16

1.14

1.12

1.10

1.09

1.08

1.07

1.06

60

1.07

1.06

1.05

1.05

1.04

1.04

1.03

1.03

70

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

80

0.94

0.95

0.95

0.96

0.96

0.97

0.97

0.97

90

0.89

0.90

0.91

0.92

0.93

0.94

0.94

0.95

100

0.85

0.86

0.88

0.89

0.90

0.91

0.92

0.93

120

0.79

0.90

0.82

0.83

0.85

0.86

0.87

0.89

140

0.73

0.75

0.77

0.79

0.81

0.82

0.84

0.85

160

0.69

0.70

0.73

0.75

0.77

0.79

0.80

0.82

GaSWCC (Amended - 2000)

6-157

6-158

Table 6-22.2. Weir Flow (Q) Over Riser Crest For Circular Risers With Trash Rack

Q = CLh3/2

Q = 3.1 x()x(D/12)x h3/2

Riser Diameter (Dr) in inches

HEAD-h

HEAD-h

In feet

12

18

24

30

36

48

54

60

in feet

Flow In Cubic Feet Per Second

0.1

0.3

0.5

0.6

0.8

0.9

1.2

1.4

1.5

0.1

0.2

0.9

1.3

1.7

2.2

2.6

3.5

3.9

4.4

0.2

0.3

1.6

2.4

3.2

4.0

4.8

6.4

7.2

8.0

0.3

0.4

2.5

3.7

4.9

6.2

7.4

9.9

11.1

12.3

0.4

0.6

4.5

6.8

9.1

11.3

13.6

18.1

20.4

22.6

0.6

0.8

10.5

13.9

17.4

20.9

27.9

31.4

34.8

0.8

1.0

19.5

24.3

29.2

39.0

43.8

48.7

1.0

1.2

25.6

32.0

38.4

51.2

57.6

64.0

1.2

1.4

40.3

48.4

64.5

72.6

80.7

1.4

1.6

49.3

59.1

78.8

88.7

98.6

1.6

1.8

70.6

94.1

105.8

117.6

1.8

2.0

82.6

110.2

124.0

137.7

2.0

2.2

127.1

143.0

158.9

2.2

2.4

162.9

181.0

2.4

2.6

183.7

204.1

2.6

2.8

228.1

2.8

GaSWCC (Amended - 2000)

3.0

Pipe, Riser, and Trash Rack Proportions

Eq. 6-10 Dr > (1.50) (Dps) where D = diameter of riser
r
Dps = diameter of principal spillway

Eq. 6-11 D > (1.4) (D )

t

r

where Dt = diameter of trash rack

Dr = diameter of riser

Riser Crest

Dt
h
Dr
D p

253.0

3.0

EXAMPLE: The peak runoff for a 2-year, 24-hour rain is 32 cfs. Select a pipe size for a head of 12 feet and length of 100 feet. From Table 6-22.1, 38.2 x 0.89 = 34 cfs discharge for a 24-inch diameter pipe.

Using Equation 6-10

Dr



(1.5) (D ) p

Dr (1.5) (24) 36 inch diameter riser

Using Equation 6-11

Dt (1.4) (Dr)

Dt (1.4) (36) 50 inch diameter (Use 54 inch)

Determine h - From Table 6-22.2

Q = 34 cfs

Dr = 36"

h = 1.2'

NOTE: h = minimum distance between the crest of the riser and the crest of the emergency spillway.

PERSPECTIVE VIEW

PVC Tee

PVC End Cap
PCV Pipe with Holes in Underside

Water Surface

Hole in Orifice Plate

PVC Pipe

Flexible Hose

Bottom Surface

Figure 6-22.4 - Skimmer Outlet

PVC Pipe

3 at 120 - 3/8" Stud with Nut and 2" O.D. Washer

Dt
3"

Removable Top - 10 Ga. Expanded Metal
3 at 120 - 5/8" Rods (Supports)-Use 5 Support Rods and
Jam Nuts for Diameters 54" and Larger

2'-0" 1'-0" 1'-0"
8" 4"

C.S. Pipe

3 at 120 - 1/2" Nut, Weld to C.S. Pipe 1/2" Jam Nut, 1/2" Bolt

Typical Trash Rack

Figure 6-22.5

GaSWCC (Amended - 2000)

6-159

Angle of stub to be shown Angle based on barrel grade
Drain (optional)

Corrugated metal riser Pipe
Flow

T 9"
4"

Base Thickness (usually 18")

Square Base B

2-#6 (min.) Bars placed at right angles and projecting into sides of riser to help anchor riser to concrete base

CONCRETE RISER BASE DETAIL
Figure 6-22.6

Table 6-22.3

Riser Pipe Diameter (in)
12 18 21 24 30 36 48 54 60

Buoyant Force (lbs/V.F. of
Riser Height)1
49.0 110.3 150.1 196.0 306.3 441.1 784.1 992.4 1225.2

Volume of Concrete per Vertical Foot of
Riser Height (c.f./V.F.) Needed to Prevent Flotation2
0.69 1.54 2.10 2.75 4.29 6.18 10.98 13.90 17.16

EXAMPLE: Find the volume of concrete required to stabilize a 24 inch diameter riser 10 feet high.

VOL. = (2.75 cu.ft/V.F.) (10 feet) = 27.5 cu. ft. = 1 cu. yd.

6-160

CONCRETE VOLUME REQUIRED TO PREVENT FLOTATION OF RISER
GaSWCC (Amended - 2000)

Level Contol Section

Level Contol Section

CL
Berm Exit Channel

CL
Exit Channel

Inlet Channel

Embankment

Inlet Channel

(Note: Neither the location nor

the alignment of the level por-

tion has to coincide with the

center line of dam.)
CL

Excavated Earth Spillway

Optional with sod or riprap on wing dike

PLAN VIEW OF EARTH SPILLWAYS
Water Surface

Hp Se Inlet Channel

L
Level Portion

Exit Channel S

Wing Dike Embankment (Note: Use care to keep all machinery and traffic out of the spillway discharge area to protect sod.)
(So)

PROFILE ALONG CENTERLINE

3 1

b
CROSS-SECTION OF CONTROL SECTION
LEGEND: Hp = Difference in Elevation between Crest of Earth Spillway at the Control Section and
Water Surface in resevoir, in feet. b = Bottom Width of Earth Spillway at the Control Section, in feet. (Table 6-22.4) Q = Total Discharge, in cfs. V = Velocity, in feet per second, that will exist in Channel below Control Section, at
Design Q, if constructed to slope (S) that is shown (Table 6-22.4) S = Flattest Slope (S), in %, allowable for Channel below Control Section. (Table 6-22.4) Se = Entry Slope So = Exit Slope
NOTES: 1. For Q, V, S relationship see the chart on the following page. 2. For a given Hp, a decrease in the exit slope as given in the table decreases spillway
discharge, but increasing the exit slope from S does not increase discharge. If an exit slope (So) is steeper than S is used, then velocity (Vo) in the exit channel will increase according to the following relationship:
Vo = V(So/S)0.3

GaSWCC (Amended - 2000)

Figure 6-22.7

6-161

6-162

GaSWCC (Amended - 2000)

STAGE (Hp)
IN FEET 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1

SPILLWAY
VARIABLES Q V S Q V S Q V S Q V S Q V S Q V S Q V S Q V S Q V S Q V S Q V S Q V S Q V S Q V S Q V S Q V S Q V S

Table 6-22.4. Design Data For Earth Spillways

8 6 2.7 3.9 8 3.0 3.7 11 3.2 3.5 13 3.5 3.3 17 3.7 3.2 20 4.0 3.1 23 4.2 2.9 28 4.4 2.9 32 4.5 2.8 37 4.7 2.8 41 4.8 2.7 46 5.0 2.6 52 5.2 2.6 58 5.3 2.5 64 5.5 2.5 71 5.6 2.5 77 5.7 2.4

10 7 2.7 3.9 10 3.0 3.7 13 3.2 3.5 16 3.5 3.3 20 3.8 3.1 24 4.0 3.0 28 4.2 2.9 33 4.4 2.9 38 4.6 2.8 44 4.8 2.7 50 4.9 2.7 56 5.1 2.6 62 5.2 2.6 69 5.4 2.5 76 5.5 2.5 83 5.7 2.4 91 5.8 2.4

BOTTOM WIDTH (b) IN FEET

12 8 2.7 3.9 12 3.0 3.7 16 3.3 3.4 19 3.5 3.3 24 3.8 3.1 29 4.0 3.0 34 4.2 2.9 40 4.4 2.8 46 4.6 2.8 51 4.8 2.7 58 4.9 2.6 65 5.1 2.6 72 5.2 2.5 81 5.4 2.5 88 5.5 2.5 97 5.7 2.4 107 5.9 2.4

14 10
2.7 3.9 14 3.0 3.7 18 3.3 3.4 22 3.6 3.2 28 3.8 3.1 33 4.0 3.0 39 4.3 2.9 45 4.4 2.8 53 4.6 2.7 59 4.8 2.7 66 5.0 2.6 75 5.1 2.6 83 5.3 2.5 93 5.5 2.5 102 5.6 2.4 111 5.7 2.4 122 5.9 2.4

16 11
2.7 3.8 16 3.0 3.6 20 3.3 3.4 26 3.6 3.2 32 3.8 3.1 38 4.0 3.0 44 4.3 2.9 51 4.4 2.8 58 4.6 2.7 66 4.8 2.7 75 5.0 2.6 84 5.1 2.5 94 5.3 2.5 104 5.5 2.4 114 5.6 2.4 125 5.8 2.4 135 5.9 2.4

18 13
2.7 3.8 18 3.0 3.7 23 3.3 3.4 29 3.6 3.2 35 3.8 3.1 42 4.0 3.0 49 4.3 2.9 58 4.5 2.8 65 4.6 2.7 74 4.8 2.7 85 5.0 2.6 94 5.2 2.5 105 5.3 2.5 116 5.5 2.4 127 5.6 2.4 138 5.8 2.4 149 5.9 2.3

20 14
2.7 3.8 20 3.0 3.6 25 3.3 3.4 32 3.6 3.2 39 3.8 3.1 47 4.0 3.0 54 4.3 2.9 64 4.5 2.8 73 4.7 2.7 82 4.8 2.7 92 5.0 2.6 104 5.2 2.5 115 5.3 2.5 127 5.5 2.4 140 5.7 2.4 153 5.8 2.4 162 5.9 2.3

22 15
2.7 3.8 22 3.0 3.6 28 3.3 3.4 35 3.6 3.2 43 3.8 3.1 51 4.0 3.0 60 4.3 2.9 69 4.5 2.8 80 4.7 2.7 90 4.8 2.6 101 5.0 2.6 112 5.2 2.5 126 5.4 2.5 138 5.5 2.4 152 5.7 2.4 164 5.8 2.4 177 6.0 2.3

24 17
2.7 3.8 24 3.0 3.6 30 3.3 3.4 38 3.6 3.2 47 3.8 3.1 56 4.0 3.0 65 4.3 2.9 76 4.5 2.8 86 4.7 2.7 96 4.8 2.6 108 5.0 2.6 122 5.2 2.5 135 5.4 2.5 150 5.5 2.4 164 5.7 2.4 178 5.8 2.3 192 6.0 2.3

26 18
2.7 3.8 26 3.0 3.6 33 3.3 3.4 42 3.6 3.2 51 3.8 3.1 61 4.0 3.0 70 4.3 2.8 80 4.5 2.8 91 4.7 2.7 103 4.9 2.6 116 5.0 2.6 132 5.2 2.5 145 5.4 2.5 160 5.5 2.4 175 5.7 2.4 193 5.8 2.3 207 6.0 2.3

28 20
2.7 3.8 28 30 3.6 35 3.3 3.4 45 3.6 3.2 53 3.8 3.1 63 4.0 3.0 74 4.3 2.8 86 4.5 2.8 99 4.7 2.7 111 4.9 2.6 125 5.0 2.6 142 5.2 2.5 156 5.4 2.5 171 5.5 2.4 188 5.7 2.4 204 5.8 2.3 220 6.0 2.3

30 21
2.7 3.8 30 3.0 3.6 38 3.3 3.4 46 3.6 3.2 57 3.8 3.1 68 4.0 3.0 79 4.3 2.8 92 4.5 2.8 106 4.7 2.7 119 4.9 2.6 133 5.0 2.6 149 5.2 2.5 167 5.4 2.5 182 5.6 2.4 201 5.7 2.4 218 5.9 2.3 234 6.0 2.3

32 22
2.7 3.8 32 3.0 3.6 41 3.3 3.4 48 3.6 3.2 60 3.8 3.1 72 4.0 3.0 84 4.3 2.8 98 4.5 2.8 112 4.7 2.7 127 4.9 2.6 142 5.0 2.6 158 5.2 2.5 175 5.4 2.5 194 5.6 2.4 213 5.7 2.4 232 5.9 2.3 250 6.0 2.3

34 24
2.7 3.8 34 3.0 3.6 43 3.3 3.4 51 3.6 3.2 64 3.8 3.1 77 4.0 3.0 89 4.3 2.8 104 4.5 2.8 119 4.7 2.7 134 4.9 2.6 150 5.0 2.6 168 5.2 2.5 187 5.4 2.5 204 5.6 2.4 225 5.7 2.4 245 5.9 2.3 267 6.0 2.3

36 25
2.7 3.8 35 3.0 3.6 44 3.3 3.4 54 3.6 3.2 68 3.8 3.1 81 4.0 3.0 95 4.3 2.8 110 4.5 2.8 125 4.7 2.7 142 4.9 2.6 160 5.1 2.5 178 5.2 2.5 196 5.4 2.5 214 5.6 2.4 235 5.7 2.4 256 5.9 2.3 276 6.0 2.3

38 27
2.7 3.8 37 3.0 3.6 46 3.3 3.4 57 3.6 3.2 71 3.8 3.1 86 4.0 3.0 100 4.3 2.8 116 4.5 2.8 133 4.7 2.7 150 4.9 2.6 169 5.1 2.5 187 5.2 2.5 206 5.4 2.5 226 5.6 2.4 248 5.7 2.4 269 5.9 2.3 291 6.0 2.3

40 28
2.7 3.8 39 3.0 3.6 48 3.3 3.4 60 3.6 3.2 75 3.8 3.1 90 4.0 3.0 105 4.3 2.8 122 4.5 2.8 140 4.7 2.7 158 4.9 2.6 178 51 2.5 197 5.2 2.5 217 5.4 2.5 233 5.6 2.4 260 5.7 2.4 283 5.9 2.3 305 6.0 2.3

DATA TO RIGHT OF HEAVY VERTICAL LINES SHOULD BE USED WITH CAUTION, AS THE RESULTING SECTIONS WILL BE EITHER POORLY PROPORTIONED, OR HAVE VELOCITIES IN EXCESS OF 6 FEET PER SECOND.

Source: USDA-SCS
GaSWCC (Amended - 2000)

6-163

TEMPORARY SEDIMENT BASIN DESIGN DATA SHEET EXAMPLE PROBLEM
Computed by ________ _ Date ______ Checked by__________ _ Date ______
Project Name Independence School, Paradise City Basin No. ____________ 1__________________ Total area draining to basin = 18.1 acres Disturbed area draining to basin = 18.1 acres
Volume 1. Compute minimum required storage volume (V )
s
Vs = 67 cy/ac * 18.1 acres = 1212.7 cy 2. Compute volume of basin at clean-out (Vc)
Vc = 22 cy/ac * 18.1 acres = 398.2 cy 3. Determine elevation corresponding to minimum required storage volume, Vs
Minimum riser crest elevation = 1052.5 ft (determined by stage/storage relationship) 4. Determine elevation corresponding to clean-out volume, Vc
Clean-out elevation = 1051.9 ft (determined by stage/storage relationship) Note: Clean-out elevation shall be clearly marked on the riser or marked by a post near the riser. 5. Compute length of riser Riser length = Minimum elevation of riser crest - Lowest elevation of pipe at riser Riser length = 1052.5 ft - 1050.0 ft Riser length = 2.5 ft
Stormwater Runoff 6. Compute peak discharge from a 2-yr, 24-hr storm event. Q = 26 cfs (Attach runoff computation sheet.)
2
7. Compute peak discharge from a 25-yr, 24-hr storm event. Q25 = 46 cfs (Attach runoff computation sheet.)
Surface Area/Configuration Design 8. Compute minimum basin surface area (SA )
min
SAmin = 0.01 ac/cfs * Q2 SAmin = 0.01 ac/cfs * 26 cfs SAmin = 0.26 ac = 43560 sf/ac * 0.26 ac = 11310 sf 9. Check available area at elevation of riser crest Available area = 18532 sf (determined by stage/storage relationship) Available area > SAmin ? Yes ___X___ No ______ 10. Compute required length to achieve 2:1 L:W ratio Average width = 80 ft Required length = 2 * average width Required length = 2 * 80 ft Required length = 160 ft Available length = 170 ft 2:1 L:W ratio satisfied? Yes ___X___ No ______ If no, refer to Figure 6-22.2 for baffle designs. Note any required baffles on E&SC plan and include calculations and details for baffle(s).

6-164

GaSWCC (Amended - 2000)

TEMPORARY SEDIMENT BASIN DESIGN SHEET Project Name Independence School, Paradise City Page 2

Principal Spillway (ps)

11. Determine maximum principal spillway capacity = Q2 = 26 cfs 12. Compute the vertical distance between the centerline of the outlet pipe and the emergency spillway crest

(H)

H = 9.75 ft

13. Compute the total pipe length of the principal spillway, L, using Figure 6-22.3.

L = [A - (B+C)/2 ] [Zu+Zd] + T + E

L = 70 ft

14. Determine diameter of principal spillway (Dps) and flow through the principal spillway (Q) from Table 6-

22.1 using H and Q2.

D = 24 in.

Q = 33.1 cfs (value directly from table)

ps

15. Compute actual flow through the principal spillway, using Table 6-22.1 to determine the correction factor

for pipe length, L.

Qps = Q * correction factor = 33.1 cfs * 1.00 Qps = 33.1 cfs 16. Compute riser diameter (D )
r
Dr > 1.5 * Dps Dr > 1.5 * 24 in. D > 36 in.
r
Dr = 36 in. 17. Compute trash rack diameter (Dt)
Dt > 1.4 * Dr Dt > 1.4* 36 in. D > 50.4 in.
t
Dt = 54 in. 18. Determine the minimum distance between the riser crest and the emergency spillway crest, h, using

Table 6-22.2 D , and Q .

r

ps

h = 1.1 ft

Concrete Riser Base Design 19. Determine the volume of concrete per vertical foot of riser height needed (from Table 6-22.3) to prevent flotation. Required volume of concrete per vertical foot = 6.18 cf/v.f. 20. Compute total volume of concrete required. Total required volume of concrete = Required volume per vertical foot * Riser length Total required volume of concrete = 6.18 cf/v.f. * 2.5 ft Total volume of concrete required = 15.45 cf 21. Assume base thickness (usually 18") (B). B = 18 in = 1.5 ft 22. Compute required surface area. Required surface area = Total volume required / B Required surface area = 15.45 cf / 1.5 ft Required surface area = 10.3 sf 23. Compute riser base length (l) and width (w) (assume square base). l = w = (required surface area )1/2 l = w = (10.3 sf)1/2 I = w = 3.21 ft = 12in/ft * 3.21 ft = 39 in.

GaSWCC (Amended - 2000)

6-165

TEMPORARY SEDIMENT BASIN DESIGN SHEET Project Name Independence School, Paradise City Page 3

Anti-Seep Collar Design

24. Determine if anti-seep collar is required. If yes to any of the following conditions, a collar is required:

______ The settled height of the dam is greater than 15 feet.

______ The principal spillway diameter (Dps) is smooth pipe larger than 8". ___X___ The principal spillway diameter (Dps) is corrugated metal pipe larger than 12". 25. Determine size of anti-seep collar required.

___X___ 18-inch projection (for heads (H) less than or equal to 10 feet).

______ 24-inch projection (for heads (H) greater than 10 feet).

Emergency Spillway (es)

26. Compute minimum capacity of emergency spillway (Qes)

Qes = Q25 - Qps = 46 cfs - 33 cfs

Qes = 13 cfs

27. Determine stage (Hp), bottom width (b), velocity (V) and minimum exit slope (S) using Table 6-22.4 and

Q.

es

Hp = 0.7 ft

b = 10 ft V = 3.2 fps S = 3.5 %

28. Actual entrance channel slope, Se = 5 %

29. Actual exit channel slope, S = 7 %

o

Note: If So is steeper than S (from Table 6-22.4), then the velocity in the exit channel will increase.

a.) Calculate exit velocity (Vo)

Vo = V (So /S) 0.3 = 3.8 fps *(7 / 35) 0.3

Vo = 4.7 fps

Note: Refer to Channel Stabilization (Ch) to determine the proper lining for the emergency spillway.

Grass ___X___ Rip-rap ______Concrete ______

Design Elevations 30. Riser crest elevation = 1052.5 ft 31. Compute minimum emergency spillway crest elevation Minimum emergency spillway crest elevation = Riser crest elevation + h Minimum emergency spillway crest elevation = 1052.5 ft + 1.1 ft Minimum emergency spillway crest elevation = 1053.6 ft Actual emergency spillway crest elevation = 1053.6 ft 32. Determine design high water elevation Design high water elevation = Emergency spillway crest elevation + Stage elevation (Hp) Design high water elevation = 1053.6 ft + 0.9 ft Design high water elevation = 1054.5 ft 33. Determine elevation of top of dam Elevation of top of dam = Design high water elevation + 1 ft freeboard Elevation of top of dam = 1054.5 ft + 1 ft Elevation of top of dam = 1055.5 ft

6-166

GaSWCC (Amended - 2000)

GaSWCC (Amended - 2000)

6-167

TEMPORARY SEDIMENT BASIN DESIGN SHEET

Project Name ____________________________ Basin No. _______________________________ Total area draining to basin = ________acres Disturbed area draining to basin = ________acres

Computed by ______________ Date _____________ Checked by ______________ Date _____________

Volume
1. Compute minimum required storage volume (Vs). V = 67 cy/ac * ________ acres = ________ cy
s
2. Compute volume of basin at clean-out (Vc). Vc = 22 cy/ac * ________ acres = ________ cy
3. Determine elevation corresponding to minimum required storage volume, V . s Minimum riser crest elevation = ________ ft (determined by stage/storage relationship)
4. Determine elevation corresponding to clean-out volume, Vc. Clean-out elevation = ________ ft (determined by stage/storage relationship)
Note: Clean-out elevation shall be clearly marked on the riser or marked by a post near the riser.
5. Compute length of riser.
Riser length = Minimum elevation of riser crest - Lowest elevation of pipe at riser
Riser length = ________ ft - ________ ft
Riser length = ________ ft

Stormwater Runoff
6. Compute peak discharge from a 2-yr, 24-hr storm event.
Q2 = ________ cfs (Attach runoff computation sheet.) 7. Compute peak discharge from a 25-yr, 24-hr storm event.
Q25 = ________ cfs (Attach runoff computation sheet.)

Surface Area/Configuration Design

8. Compute minimum basin surface area (SAmin).

SAmin = 0.01 ac/cfs * Q2

SAmin = 0.01 ac/cfs * ________ cfs

SAmin =________ ac = 43560

sf/ac *________ ac = ________ sf

9. Check available area at elevation of riser crest.

Available area = ________ sf (determined by stage/storage relationship)

Available area SAmin? Yes _______ No ________ 10. Compute required length to achieve 2:1 L:W ratio.

Average width = _______ ft

Required length = 2 * average width

Required length = 2 *________ ft

Required length = ________ ft

Available length = ________ ft

2:1 L:W ratio satisfied? Yes _______ No ________

If "no", refer to Figure 6-22.2 for baffle designs. Note any required baffles on E&SC plan and include calcu-

lations and details for baffle(s).

Principal Spillway (ps)
11. Determine maximum principal spillway capacity.
Qmax = Q2 =__________ cfs 12. Compute the vertical distance between the centerline of the outlet pipe and the emergency spillway crest (H).
H = ________ ft

6-168

GaSWCC (Amended - 2000)

TEMPORARY SEDIMENT BASIN DESIGN SHEET Project Name _____________________ Page 2

13. Compute the total pipe length of the principal spillway, L, using Figure 6-22.3.

L = [A - (B+C)/2 ] [Zu+Zd] + T + E = [ _____- ( _____+_____)/2] [ _____+_____] + _____ + _____

L = ________ ft

14. Determine diameter of principal spillway (Dps) and flow through the principal spillway (Q) from Table 6-22.1

using H and Qmax.

Dps = ________ in.

Q =________ cfs (value directly from table)

15. Compute actual flow through the principal spillway, using Table 6-22.1 to determine the correction factor for

pipe length, L.

Qps = Q * correction factor = ________ cfs * ________ Qps = ________ cfs 16. Compute riser diameter (D ).
r
Dr = 1.5 * Dps Dr = 1.5 * ________ in. Dr = ________ in. Dr = ________ in. 17. Compute trash rack diameter (D ).
t
Dt = 1.4 * Dr Dt = 1.4* ________ in. D = ________ in.
t
Dt = ________ in. 18. Determine the minimum distance between the riser crest and the emergency spillway crest, h, using Table

6-22.2 Dr, and Qps. h = ________ ft

Concrete Riser Base Design 19. Determine the volume of concrete per vertical foot of riser height needed, from Table 6-22.3 to prevent flotation. Required volume of concrete per vertical foot = ________ cf/v.f. 20. Compute total volume of concrete required. Total required volume of concrete = Required volume per vertical foot * Riser length Total required volume of concrete = ________ cf/v.f. *________ ft Total volume of concrete required = ________ cf 21. Assume base thickness, B (usually 18"). B = ________ in = ________ ft 22. Compute required surface area. Required surface area = Total volume required / B Required surface area = ________ cf / ________ ft Required surface area = ________ sf 23. Compute riser base length (l) and width (w) (assume square base). l = w = (required surface area )1/2 l = w = (________ sf)1/2 l = w = ________ ft = 12in/ft* ________ ft = ________ in

Anti-Seep Collar Design
24. Determine if anti-seep collar is required. If yes, to any of the following conditions, a collar is required:
________ The settled height of the dam is greater than 15 feet.
________ The principal spillway diameter (Dps) is smooth pipe larger than 8". ________ The principal spillway diameter (D ) is corrugated metal pipe larger than 12".
ps
25. Determine size of anti-seep collar required.
________ 18-inch projection (for heads (H) less than or equal to 10 feet).
________ 24-inch projection (for heads (H) greater than 10 feet).

GaSWCC (Amended - 2000)

6-169

TEMPORARY SEDIMENT BASIN DESIGN SHEET Project Name _____________________ Page 3

Emergency Spillway (es)

26. Compute minimum capacity of emergency spillway (Qes)

Q = Q - Q = __________ cfs -__________ cfs

es

25

ps

Qes = __________ cfs

27. Determine stage (Hp), bottom width (b), velocity (V) and minimum exit slope (S) using Table 6-22.4 and Qes.

Hp = ________ ft

b = ________ ft V = ________ fps

S = ________%

28. Actual entrance channel slope, Se = ________ %

29. Actual exit channel slope, S = ________ %

o

Note: If So is steeper than S (from Table 6-22.4), then the velocity in the exit channel will increase.

a.) Calculate new exit velocity (V ) o Vo = V (So/S) 0.3 = ________ fps * (________/________) 0.3
Vo = ________ fps Note: Refer to Channel Stabilization (Ch) to determine the proper lining for the emergency spillway.

Grass ______

Rip-rap ________

Concrete ________

Design Elevations 30. Riser crest elevation = ________ ft 31. Compute minimum emergency spillway crest elevation. Minimum emergency spillway crest elevation = Riser crest elevation + h Minimum emergency spillway crest elevation = ________ ft + ________ ft Minimum emergency spillway crest elevation = ________ ft 32. Determine design high water elevation Design high water elevation = Minimum emergency spillway crest elevation + Stage elevation (Hp) Design high water elevation = ________ ft + ________ ft Design high water elevation = ________ ft 33. Determine elevation of top of dam Elevation of top of dam = Design high water elevation + 1 ft freeboard Elevation of top of dam = ________ ft + 1 ft Elevation of top of dam = ________ ft

PLEASE NOTE THAT DESIGN VALUES DETERMINED BY THIS SHEET REPRESENT THE MINIMUM REQUIREMENTS FOR A TEMPORARY SEDIMENT BASIN.

6-170

GaSWCC (Amended - 2000)

Figure 6-22.8 - Temporary Sediment Basin Cross-Sectional Detail
GaSWCC (Amended - 2000)

Elev. Cu. Yd.
"

Max. Volume of Basin

Volume when

"

Sediment Removal is

Required

Elev. Cu. Yd.

3" - 4" Stone

' Storage

Top of Dam Constructed Elev.

'

Top of Dam Settled Elev.

Emergency Spillway Crest Elevation Emergency Spillway Width

: ss

: ss

1' Freeboard ' Spillway Flow Depth

Perforate the entire riser with 1/2" holes
" Dia. Corrugated Steel Pipe
Elev.

Antiseep Collar "x "
Core Trench ' Deep, : ss ' Bottom Width

Elev.

Concrete Antiflotation Block

"x

"x

"

" Long 2 - No. 6 Steel Rebars

Rock Rip-Rap Outlet (Show dimensions and rock sizes)

6-171

6-172

Top of Dam

Elev. =

ft

Emergency Spillway Crest Elev.

=

ft

Cross-Sectional Detail of Emergency Spillway

Freeboad=

ft (1ft. minimum)

Hp =

ft

Slope = :1

Lining

Bottom width =

ft

Hp =

ft

Profile Along Centerline
Exit Channel Length = ft

Figure 6-22.9

GaSWCC (Amended - 2000)

Lining

Length =

ft

Se =

%

So =

%

Emergency Spillway

Temporary Stream

Crossing

Sr

DEFINITION
A temporary structure installed across a flowing stream or watercourse for use by construction equipment.
PURPOSE
This standard provides a means for construction vehicles to cross streams or watercourses without moving sediment into streams, damaging the streambed or channel, or causing flooding.
CONDITIONS
Temporary stream crossings shall not be used on streams with drainage areas greater than one square mile. Structures may include bridges, round pipes or pipe arches.
Temporary stream crossings should be in place for less than one year and should not be used by the general public.
DESIGN CRITERIA
Size
The structure shall be large enough to convey the full bank flow of the stream, typically flows produced by a 2-year, 24-hour frequency storm, without appreciably altering the stream flow characteristic.

Location
The temporary stream crossing shall be perpendicular to the stream. Where approach conditions dictate, the crossing may vary 15% from the perpendicular.
Overflow Protection
Structures shall be protected from washout during periods of peak discharges by diverting water around the structures. Methods to be considered for washout protection may include elevation of bridges above adjacent flood plain lands, crowning of fills over pipes, or by the use of diversions, dikes or island type structures. Two types of stream crossings that may be used are bridges and culverts. Frequency and intended use, stream channel conditions, overflow areas, potential flood damage, and surface runoff control should be considered when selecting the type of temporary stream crossing to be used.
Temporary Bridge Crossing Sr-B
A temporary access bridge causes the least erosion of the stream channel crossing when the bridge is installed and removed. It also provides the least obstruction to flow and fish migration. Provided that the bridge is properly designed and appropriate materials are used, a temporary access bridge will be long-lasting and will require little maintenance. However, it is generally the most expensive crossing to design and construct; creating the greatest safety hazard if not adequately designed, installed and maintained.
Temporary Culvert Crossing Sr-C
A temporary access culvert can control erosion effectively, but can cause erosion when it is installed and removed. It is the most common stream crossing. A temporary culvert can be easily constructed and enables heavy equipment loads to be used. However, culverts create the greatest obstruction to flood flows and are subject to blockage and washout.
Table 6-23.1 shall be used to determine the culvert size necessary to safely convey streamflow. Please note that the required pipe size is based on cross-sectional area of the pipe; e.g. if a 24 inch pipe is prescribed by Table 6-23.1, two 12 inch pipes could not be substituted because less flow area is provided.

GaSWCC (Amended - 2000)

6-173

Table 6-23.1. Corrugated Metal Pipe (CMP) Diameters For Temporary Stream Crossings a

Drainage Area Average Slope of Watershed

(Acres)

1% 4% 8% 16%

1-25

24 24 30 30

26-50

24 30 36 36

51-100

30 36 42 48

101-150

30 42 48 48

151-200

36 42 48 54

201-250

36 48 54 54

251-300

36 48 54 60

301-350

42 48 60 60

351-400

42 54 60 60

401-450

42 54 60 72

451-500

42 54 60 72

501-550

48 60 60 72

551-600

48 60 60 72

601-640

48 60 72 72

a Assumptions for determining the table: USDA-NRCS Peak Discharge Method; CN = 65; Rainfall depth (average for Georgia) = 3.7" for 2-year frequency. Pipe diameters shown in the table are in inches.

CONSTRUCTION SPECIFICATIONS

All Crossings

1. Clearing of the stream bed and banks shall be kept to a minimum.

2. All surface water from the construction site shall be diverted onto undisturbed areas adjoining the stream. Line unstable stream banks with riprap or otherwise appropriately stabilize them.

3. The structure shall be removed as soon as it is no longer necessary for project construction.

4. Upon removal of the structure, the stream shall immediately be restored to its original crosssection and properly stabilized.

Temporary Bridge Crossing Sr-B
1. The temporary bridge shall be constructed at or above bank elevation to prevent the entrapment of floating materials and debris.
2. Abutments shall be placed parallel to and on stable banks.
3. Bridges shall be constructed to span the entire channel. If the channel width exceeds eight feet (as measured from the tops of the banks), a footing, pier or bridge support may be constructed within the waterway.
4. Bridges shall be securely anchored at only one end using steel cable or chain. This will prevent channel obstruction in the event that floodwaters float the bridge. Large trees, large boulders, or driven steel anchors can serve as anchors.
Temporary Culvert Crossing Sr-C
1. The invert elevation of the culvert shall be installed on the natural streambed grade.
2. The culvert(s) shall extend a minimum of one foot beyond the upstream and downstream toe of the aggregate placed around the culvert. In no case shall the culvert exceed 40 feet in length.
3. The culvert(s) shall be covered with a minimum of one foot of aggregate. If multiple culverts are used, they shall be separated by a minimum of 12 inches of compacted aggregate fill.
MAINTENANCE
The structure shall be inspected after every rainfall and at least once a week, whether it has rained or not, and all damages repaired immediately. The structure shall be removed immediately after construction is finished, and the streambed and banks must be stabilized. Refer to specification Bf - Buffer Zone.

TO BE SHOWN ON THE EROSION AND SEDIMENT CONTROL PLAN
1. Drainage area (ac), average slope of watershed (%), and stream flow rate at bankfull flow (cfs). 2. Detailed dimensions of components for the type of crossing to be used.

6-174

GaSWCC (Amended - 2000)

TEMPORARY BRIDGE CROSSING

ABUTMENT

FLOW

50'

STEEL CABLE OR CHAIN

ACCEPTABLE ANCHOR

50'

GaSWCC (Amended - 2000)

SURFACE FLOW DIVERTED BY SWALE AND/OR DIKE

Figure 6-23.1

6-175

Coarse Aggregate 6" 1/2 Diameter of Pipe or 12", Whichever is Greater

Minimum Pipe Diameters Sized as Specified in "Pipe Diameters For Stream Crossings"
Earth Fill Covered by Appropriately Large Angular Rock

Coarse Aggregate

ELEVATION
Flow

Rip-Rap, Large Angular Rock Over Earth Fill

6-176

25' Min. Top of Bank

25' Min. Top of Bank

PLAN
GENERAL NOTES:
1. Not to scale. 2. This type of crossing can be installed in both a wet or dry
weather stream condition where the drainage area exceeds 10 acres. 3. Remove during cleanup.

Figure 6-23.2

GaSWCC (Amended - 2000)

AGGREGATE FILL

AGGREGATE FILL

12" MIN

FILTER CLOTH HIGH FLOW AREA

FILTER CLOTH

12" MIN

HIGH FLOW AREA

AGGREGATE FILL

FILTER CLOTH

FLAT BANKS

AGGREGATE FILL

FILTER CLOTH

STEEP BANKS

AGGREGATE FILL HIGH FLOW AREA

AGGREGATE FILL HIGH FLOW AREA

FILTER CLOTH
MULTIPLE PIPES

FILTER CLOTH
MULTIPLE PIPES

Figure 6-23.3 - Configuration of Temporary Culvert Crossing
GaSWCC (Amended - 2000)

6-177

6-178

GaSWCC (Amended - 2000)

Storm Drain Outlet

Protection

St

DEFINITION
Paved and/or riprapped channel sections, placed below storm drain outlets.
PURPOSE
To reduce velocity of flow before entering receiving channels below storm drain outlets.
CONDITIONS
This standard applies to all storm drain outlets, road culverts, paved channel outlets, etc., discharging into natural or constructed channels. Analysis and/or treatment will extend from the end of the conduit, channel or structure to the point of entry into an existing stream or publicly maintained drainage system.
DESIGN CRITERIA
Structurally lined aprons at the outlets of pipes and paved channel sections shall be designed according to the following criteria:
Capacity
Peak stormflow from the 25-year, 24-hour frequency storm or the storm specified in Title 12-7-1 of the Official Code of Georgia Annotated or the design discharge of the water conveyance structure, whichever is greater.
Tailwater Depth
The depth of tailwater immediately below the pipe outlet must be determined for the design capacity of the pipe. Manning's Equation may be used to determine tailwater depth. If the tailwater depth is less than half the diameter of the outlet pipe, it shall be classified as a
GaSWCC (Amended - 2000)

Minimum Tailwater Condition. If the tailwater depth is greater than half the pipe diameter, it shall be classified as a Maximum Tailwater Condition. Pipes which outlet onto flat areas with no defined channel may be assumed to have a Minimum Tailwater Condition.
Apron Length and Thickness
The apron length and d50, stone median size, shall be determined from the curves according to tailwater conditions:
Minimum Tailwater- Use Figure 6-24.1
Maximum Tailwater- Use Figure 6-24.2
Maximum Stone Size = 1.5 x d50
Apron Thickness = 1.5 x dmax
Apron Width
If the pipe discharges directly into a well-defined channel, the apron shall extend across the channel bottom and up the channel banks to an elevation one foot above the maximum tailwater depth or to the top of the bank (whichever is less). If the pipe discharges onto a flat area with no defined channel, the width of the apron shall be determined as follows:
a. The upstream end of the apron, adjacent to the pipe, shall have a width three times the diameter of the outlet pipe.
b. For a Minimum Tailwater Condition, the downstream end of the apron shall have a width equal to the pipe diameter plus the length of the apron. Refer to Figure 6-24.1.
c. For a Maximum Tailwater Condition, the down stream end shall have a width equal to the pipe diameter plus 0.4 times the length of the apron.
Refer to Figure 6-24.2.
Bottom Grade
The apron shall be constructed with no slope along its length (0.0% grade).The invert elevation of the downstream end of the apron shall be equal to the elevation of the invert of the receiving channel. There shall be no overfall at the end of the apron.
Side Slope
If the pipe discharges into a well-defined channel, the side slopes of the channel shall not be steeper than 2:1.
6-179

Alignment
The apron shall be located so that there are no bends in the horizontal alignment.
Geotextile
Geotextiles should be used as a separator between the graded stone, the soil base, and the abutments. The geotextile will prevent the migration of soil particles from the subgrade into the graded stone. The geotextile shall be specified in accordance with AASHTO M288-96 Section 7.5, Permanent Erosion Control Recommendations. The geotextile should be placed immediately adjacent to the subgrade without any voids.
Materials
The apron may be lined with riprap, grouted riprap, or concrete. The median sized stone for riprap, d50, shall be determined from the curves, Figures 6-24.1 and 624.2, according to the tailwater condition. The gradation, quality and placement of riprap shall conform to Appendix C.
Refer to Figure 6-24.4, for alternative structures to achieving energy dissipation at an outlet. For information regarding the selection and design of these alternative energy dissipators, refer to:
FHWA Standard (REF. Hydraulic Design of Energy Dissipators for Culverts and Channels; HEC No. 14, FHWA, Available from the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.
CONSTRUCTION SPECIFICATIONS
1. Ensure that the subgrade for the filter and riprap follows the required lines and grades shown in the plan. Compact any fill required in the subgrade to the density of the surrounding undisturbed material. Low areas in the subgrade on undisturbed soil may also be filled by increasing the riprap thickness.
2. The riprap and gravel filter must conform to the specified grading limits shown on the plans.

3. Geotextile must meet design requirements and be properly protected from punching or tearing during installation. Repair any damage by removing the riprap and placing another piece of filter fabric over the damaged area. All connecting joints should overlap a minimum of 1 ft. If the damage is extensive, replace the entire filter fabric.
4. Riprap may be placed by equipment, but take care to avoid damaging the filter.
5. The minimum thickness of the riprap should be 1.5 times the maximum stone diameter.
6. Construct the apron on zero grade with no overfall at the end. Make the top of the riprap at the downstream end level with the receiving area or slightly below it.
7. Ensure that the apron is properly aligned with the receiving stream and preferably straight throughout its length. If a curve is needed to fit site conditions, place it in the upper section of the apron.
8. Immediately after construction, stabilize all disturbed areas with vegetation.
9. Stone quality - Select stone for riprap from field stone or quarry stone. The stone should be hard, angular, and highly weather-resistant. The specific gravity of the individual stones should be at least 2.5.
10. Filter - Install a filter to prevent soil movement through the openings in the riprap. The filter should consist of a graded gravel layer or a synthetic filter cloth. See Appendix C; p. C-1.
MAINTENANCE
Inspect riprap outlet structures after heavy rains to see if any erosion around or below the riprap has taken place or if stones have been dislodged. Immediately make all needed repairs to prevent further damage.

TO BE SHOWN ON THE EROSION AND SEDIMENT CONTROL PLAN
1. The flow characteristics of the pipe at full flow including pipe diameter, flow rate (cfs), velocity (fps), and tailwater condition.
2. The dimensions of the apron including length (La), width at the headwall (W1), downstream width (W2), average stone diameter (d50), and stone depth (D) designed in accordance with Figures 6-24.1 and 624.2.

6-180

GaSWCC (Amended - 2000)

3Do

d = 60 d = 66

Outlet pipe diameter (Do)

W = Do =+ La
La Tailwater < 0.5Do

90 80

d = 90

d = 54

= 84 96

Minimum

Length 50

of

Apron

(La)(ft) 60

70

d = 36

d = 42

d = 48

d =

d

d = 78

d = 72

20

30

40 d = 12

d = 15

d = 18

d = 21 d = 24 d = 27 d = 30

v = 40

4

v = 35 3

==847728

d d =

d = 66

d 90

10

v = 30

=

d = 60

d

0

2

d = 96

d = 48 d = 54

d = 27 d = 42 d = 30

v = 5

v

=

v 10

= 15 d =

12

d

=

15

v

=

20 d

=

18

v

=

25 d =

21

d = 24

d = 36

3

5

10

20

50

100

200

Discharge (ft3/sec)

1

0

500

1000

Curves may not be extrapolated.

d50 Riprap Size (ft)

Figure 6-24.1 - Design of Outlet Protection From a Round Pipe Flowing Full, Minimum Tailwater Condition (Tw < 0.5 Diameter)

GaSWCC (Amended - 2000)

6-181

3Do

Outlet
pipe diameter(Do)

W = Do + 0.4La

120

La Tailwater > 0.5Do

110 100

90

Minimum Length of Apron (La)(ft)

80

70

d d= =2730 d = 36

60

d = 21 d = 24

50

d = 18

40

d = 15

30 20

12 = d

10

v = 25 24

27 = d

0

v = 10

v = 20

d = 12

v = 15 d

=

15

d = 18

21 d =

= d

3

5

10

20

50

100

Discharge (ft3/sec)

d = 36

d = 30

d = 42

d

=

d 42

=

v = 30 200

Curves may not be extrapolated.

d 48

=

d 54

=

d = 48 d = 54 d = 60 d = 66 d = 72 d = 78 d = 84 d = 90 d = 96

d 60

=

d

66 72

3

2

=9=07884

d =

d

96

=

d

=

1

d

0

500

1000

d50 Riprap Size (ft)

Figure 6-24.2 - Design of Outlet Protection From a Round Pipe Flowing Full, Maximum Tailwater Condition (Tw > 0.5 Diameter)

6-182

GaSWCC (Amended - 2000)

Pipe Outlet to Flat Area No Well-defined Channel

3d A

A

d

Plan La

D Section AA
Pipe Outlet to Well-defined Channel

Filter blanket

A

A

Plan La
Section AA

D
Filter blanket

Notes
1. La is the length of the riprap apron.
2. D = 1.5 times the maximum stone diameter but not less than 6".
3. In a well-defined channel extend the apron up the channel banks to an elevation of 6" above the maximum tailwater depth of to the top of the bank, whichever is less.
4. A filter blanket or filter fabric should be installed between the riprap and soil foundation.

Figure 6-24.3 - Riprap Outlet Protection (Modified From Va SWCC)

GaSWCC (Amended - 2000)

6-183

Virginia Department of Highways and Transportation

Colorado State University Rigid Boundary Basin

USBR Type IV Basin

St. Anthony Falls Stilling Basin

Contra Costa County, Calif.

Straight Drop Spillway Stilling Basin

USBR Type VI Baffle Wall Basin

T-fitting on CMP Outlet

Figure 6-24.4 - Alternative Structures For Energy Dissipation at an Outlet (Modified From Goldman, Jackson, and Bursztynsky)

6-184

GaSWCC (Amended - 2000)

Surface Roughening Su
DEFINITION
Providing a rough soil surface with horizontal depressions created by operating a tillage or other suitable implement on the contour, or by leaving slopes in a roughened condition by not fine-grading them.
PURPOSE
The purposes of surface roughening are to aid in establishment of vegetative cover with seed, to reduce runoff velocity and increase infiltration and to reduce erosion and provide for sediment trapping.
CONDITIONS
All slopes steeper than 3:1 require surface roughening, either stair-step grading, grooving, furrowing, or tracking if they are to be stabilized with vegetation. However, if the slope is to be stabilized with erosion control blankets or soil reinforcement matting, the soil surface should not be roughened.
Areas with grades less steep than 3:1 should have the soil surface lightly roughened and loosened to a depth of 2 to 4 inches prior to seeding. Areas which have been graded and will not be stabilized immediately may be roughened to reduce runoff velocity until seeding takes place. Slopes with a stable rock face do not require roughening or stabilization.
DESIGN CRITERIA
Graded areas with smooth, hard surfaces give a false impression of "finished grading" and a job well done. It is difficult to establish vegetation on such surfaces due to reduced water infiltration and the potential for erosion. Rough slope surfaces with uneven soil and rocks left in place may appear unattractive or unfinished at first, but encourage water infiltration, speed the estab-
GaSWCC (Amended - 2000)

lishment of vegetation, and decrease runoff velocity. Rough, loose soil surfaces give lime, fertilizer and seed some natural coverage. Niches in the surface provide microclimates which generally provide a cooler and more favorable moisture level than hard flat surfaces. This aids seed germination.
There are different methods of achieving a roughened soil surface on a slope, and the selection of an appropriate method depends upon the type of slope. Roughening methods include stair-step grading, grooving, and tracking. Factors to be considered in choosing a method are slope steepness, mowing requirements, and whether the slope is formed by cutting or filling.
1. Disturbed areas which will not require mowing maybe stair-step graded, grooved, or left rough after filling.
2. Stair-step grading is particularly appropriate in soils containing large amounts of soft rock. Each "step" catches material which sloughs from above, and provides a level site where vegetation can become established.
3. Areas which will be mowed (these areas should have slopes less steep than 3:1) may have small furrows left by discing, harrowing, raking, or seed planting machinery operated on the contour.
4. It is important to avoid excessive compacting of the soil surface when scarifying. Tracking with bulldozer treads is preferable to not roughening at all, but is not as effective as other forms of roughening, as the soil surface is severely compacted and runoff is increased.
CONSTRUCTION SPECIFICATIONS
Cut Slopes Steeper than 3:1
Cut slopes with a gradient steeper than 3:1 should not be mowed. They shall be stair-step graded or grooved (see Figure 6-25.1).
1. Stair-step grading may be carried out on any material soft enough to be ripped with a bulldozer. Slopes consisting of soft rock with some subsoil are particularly suited to stair-step grading.
The ratio of the vertical cut distance to the horizontal distance shall be less than 1:1 and the horizontal portion of the "step" shall slope toward the vertical wall.
Individual vertical cuts shall not be more than 30 inches on soft soil material and not more than 40 inches in rocky materials.
6-185

2. Grooving consists of using machinery to create a series of ridges and depressions which run perpendicular to the slope (on the contour).
Grooves may be made with any appropriate implement which can be safely operated on the slope and which will not cause undue compaction. Suggested implements include discs, tillers, spring harrows, and the teeth on a frontend loader bucket. Such grooves shall not be less than 3 inches deep nor further than 15 inches apart.
Fill Slopes Steeper than 3:1
Fill slopes with a gradient steeper than 3:1 should not be mowed. They shall be grooved or allowed to remain rough as they are constructed. Method (1) or (2) below may be used.
1. Groove according to #2 of "Cut Slopes Steeper than 3:1".
2. As lifts of the fill are constructed, soil and rock material may be allowed to fall naturally onto the slope surface (see Figure 6-25.1).
Colluvial materials (soil deposits at the base of slopes or from old stream beds) shall not be used in fills as they flow when saturated.
Cuts, Fills, and Graded Areas Which Will Be Mowed (less than 3:1)
Mowed slopes should not be steeper than 3:1. Excessive roughness is undesirable where mowing is planned.

These areas may be roughened with shallow grooves such as remain after tilling, discing, harrowing, raking, or use of a multipacker-seeder. The final pass of any such tillage implement shall be on the contour (perpendicular to the slope).
Grooves formed by such implements shall be not less than one inch deep and not further than 12 inches apart.
Fill slopes which are left rough as constructed may be smoothed with a dragline or pickchain to facilitate mowing.
Roughening With Tracked Machinery
Roughening with tracked machinery on clayed soils is not recommended unless no alternatives are available. Undue compaction of surface soil results from this practice. Sandy soils do not compact severely and may be tracked. In no case is tracking as effective as the other roughening methods described.
When tracking is the chosen surface roughening technique, it shall be done by operating tracked machinery up and down the slope to leave horizontal depressions in the soil. As few passes of the machinery as possible should be made to minimize compaction.
Seeding
Roughened areas shall be seeded and mulched as soon as possible to obtain optimum seed germination and seeding growth. Refer to specifications Ds1, Ds2, Ds3, and Ds4 - Disturbed Area Stabilization (With Mulching Only,Temporary Seeding, Permanent Vegetation, and Sodding), respectively.

6-186

GaSWCC (Amended - 2000)

30" - 40"
maximum

Debris from slope above is caught by steps
Drainage

40" - 50"
maximum

Water, soil, and fertilizer are held by steps - plants can become established on the steps.

STAIR STEPPING CUT SLOPES

12" - 15"
maximum
3"
minimum

Grooving is cutting furrows along the contour of a slope. Irregularities in the soil surface catch rainwater and provide some coverage of lime, fertilizer and seed.

GROOVING SLOPES

Figure 6-25.1

GaSWCC (Amended - 2000)

6-187

Each lift of the fill is compacted, but the outer face of the slope is allowed to remain loose so that the rocks, clods, etc. reach the natural angle of repose.
FILL SLOPE TREATMENT

Dozer treads create grooves perpendicular to the slope.

Slope

6-188

TRACKING
Figure 6-25.2

GaSWCC (Amended - 2000)

Topsoiling

Tp

DEFINITION
Stripping off the more fertile top soil, storing it, then spreading it over the disturbed area after completion of construction activities.
PURPOSE
To provide a suitable soil medium for vegetative growth on areas where other measures will not produce or maintain a desirable stand.
CONDITIONS
This practice is recommended for sites of 2:1 or flatter slopes where:
1. The texture of the exposed subsoil or parent material is not suitable to produce adequate vegetative growth.
2. The soil material is so shallow that the rooting zone is not deep enough to support plants with continuing supplies of moisture and food.
3. The soil to be vegetated contains material toxic to plant growth.
CONSTRUCTION SPECIFICATIONS
Materials
Topsoil should be friable and loamy, free of debris, objectionable weeds and stones and contain no toxic substance that may be harmful to plant growth. A pH range of 5.0-7.5 is acceptable. Soluble salts should not exceed 500 ppm.

Testing
Field exploration should be made to determine whether the quantity and quality of surface soil justifies stripping.
Stripping
Stripping should be confined to the immediate construction area.
A 4 to 6 inch stripping depth is common, but may vary depending on the particular soil.
Topsoil pH
If pH value is less than 6.0, lime shall be applied and incorporated with the topsoil to adjust the pH to 6.5 or higher. Topsoils containing soluble salts greater than 500 parts per million shall not be used.
Stockpiles
The location of topsoil stockpiles should not obstruct natural drainage or cause off-site environmental damage.
Stabilization
Stockpiles shall be contained by sediment barriers to prevent sedimentation on adjacent areas. Stockpiles shall be stabilized in accordance with specifications Ds1 and Ds2 - Disturbed Area Stabilization (With Mulching) and (With Temporary Grassing), respectively, or Pm - Polyacrylamide or Tb - Tackifiers and Binders.
Site Preparation (Where topsoil is to be added)
Topsoiling - When topsoiling, maintain needed erosion control practices such as diversions, grade stabilization structures, berms, dikes, level spreaders, waterways, sediment basins, etc.
Grading - Grades on the areas to be topsoiled which have been previously established shall be maintained.
Liming - Soil tests should be used to determine the pH of the soil. Where the pH of the subsoil is 5.0 or less or composed of heavy clays, agricultural limestone shall be spread at the rate of 100 pounds per 1,000 square feet. Lime shall be distributed uniformly over designated areas and worked into the soil in conjunction with tillage operations as described in the following procedure.

GaSWCC (Amended - 2000)

6-189

Bonding - Use one of the following methods to insure bonding of topsoil and subsoil:
1. Tilling. After the areas to be topsoiled have been brought to grade, and immediately prior to dumping and spreading the topsoil, the subgrade shall be loosened by discing or scarifying to a depth of at least 3 inches to permit bonding of the topsoil to the subsoil.
2. Tracking. Passing a bulldozer over the entire surface area of the slope to leave horizontal depressions.
Applying Topsoil
1. Topsoil should be handled only when it is dry enough to work without damaging soil structure.
2. A uniform application of 5 inches (unsettled) is recommended, but may be adjusted at the discretion of the engineer or landscape architect.
Table 6-26.1. Cubic Yards Of Topsoil Required For Application To Various Depths

Depth (Inches)
1 2 3 4 5 6

Per 1,000 Square Feet
3.1 6.2 9.3 12.4 15.5 18.6

Per Acre 134 268 403 537 672 806

6-190

GaSWCC (Amended - 2000)

Vegetated Waterway or

Stormwater Conveyance

Channel

Wt

DEFINITION
A natural or constructed channel that is shaped or graded to required dimensions and established in suitable vegetation for the stable conveyance of runoff.
PURPOSE
To dispose of runoff without causing damage either by erosion or by flooding.
CONDITIONS
This standard applies to all sites where added channel capacity and/or stabilization is required to control erosion resulting from concentrated runoff and where such control can be achieved by this practice alone or in combination with others.
DESIGN CRITERIA
Capacity
The minimum capacity shall be that required to convey the peak runoff expected from a 25-year, 24-hour storm or the storm specified in Title 12-7-1 of the Official Code of Georgia Annotated. Peak runoff values used in determining the capacity requirements shall be as outlined in Appendix A or by other accepted methods.
The design of a waterway is based on the determination of channel dimensions that will carry the estimated flow without damage to the channel or its lining. Vegetative linings vary in their protective ability according to type and density. Therefore, safe velocities under various conditions are a matter for careful consideration.
GaSWCC (Amended - 2000)

Velocity
In designing grassed waterways, care must be taken to ensure that the design velocity is well within the limits of permissible velocities given in Table 6-27.1. These values apply to uniform good stands of each type of cover.
Cross Section
The minimum design capacity of a waterway receiving water from developing areas, diversions, or other tributary channels shall be that depth required to keep the design water surface elevation in the channel to prevent overflow.
The bottom width of waterways or outlets shall not exceed 50 feet unless multiple or divided waterways or other means are provided to control meandering of low flows within this limit. See Figure 6-27.1.
Drainage
Tile or other suitable subsurface drainage measures shall be provided for sites having high water tables or seepage problems. Where there is base flow, a stone center or lined channel will be required. See Appendix C for rock riprap specifications.
Stone Center
Stone center waterways shall be constructed as shown in Figure 6-27.2 and Table 6-27.2 and stabilized with riprap according to the specification Riprap - Appendix C.
Geotextiles should be used as an erosion control measure beneath the riprap center. The geotextile shall be specified in accordance with AASHTO M288-96 Section 7.5, Permanent Erosion Control Requirements.
Vegetative Retardance Factor
The design of a vegetated waterway is more complicated than for a bare channel since the value for "n" varies where grass linings are used. Tests show that vegetation tends to bend and oscillate under the influence of velocity and depth of flow. Thus the retardance to flow varies as these factors change.
Five general retardance curves designated as A, B, C, D, and E have been developed for various cover conditions. The vegetated conditions under which the various retardance values apply in Georgia are shown in Table 6-27.1. These cover classifications are based on tests in experimental channels when the covers were green and generally uniform.
6-191

RETARDANCE PLANT HT. NOT MOWED
RETARDANCE PLANT HT. MOWED MAXIMUM PERMISSIBLE VELOCITY, V1 FEET PER SECOND

Table 6-27.1. Permissible Velocities and Retardances for Vegetated and Rock-Lined Waterways

VEGETATIVE COVER TYPE

FOR CAPACITY
AND V2

GOOD STAND

FOR STABILITY
AND V1

BERMUDA GRASS

B

12"

D

2-6"

5

BAHIA

C

6-12"

D

2-6"

4

TALL FESCUE

GRASS MIXTURES1

B

18"

D

6"

4

SERICEA LESPEDEZA

WEEPING LOVEGRASS

B

19"

D

2-6"

3

STONE CENTER

RIPRAP STONE SIZE CAN BE DETERMINED IN APPENDIX C.

1 Mixtures of Tall Fescue, Bahia, and/or Bermuda.

NOTE: For Planting instructions, refer to Disturbed Area Stabilization (With Permanent Vegetation) Ds3, p. 6-139.

6-192

GaSWCC (Amended - 2000)

"The Stormwater Conveyance Channel Design Sheets" shall be used to design grass-lined channels. These design sheets include the cross-sectional detail that shall be included on the erosion and sediment control plan.
If a stone center waterway is selected, it shall be designed according to Tables 6-27.2 and 6-27.3. Crosssectional details on the erosion and sediment control plan shall include all information noted in Figure 6-27.2, including the maximum stone size of the rock to be used.
An example of how to design a grass-lined channel with a parabolic cross-section is provided on p. 6-198.
CONSTRUCTION SPECIFICATIONS
1. All trees, brush, stumps, obstructions, and other objectionable material shall be removed and disposed of so as not to interfere with the proper functioning of the waterway.
2. The waterway or outlet shall be excavated or shaped to line, grade, and cross section as required to meet the criteria specified herein. It will be free of bank projections or other irregularities which will impede normal flow. If the channel must have erosion protection other than vegetation, the lining shall not compromise the capacity of the emergency spillway, i.e. the channel shall be over-excavated so that the lining will be flush with the slope surface.
3. Fills shall be compacted as needed to prevent unequal settlement that would cause damage in the completed waterway.
4. All earth removed and not needed in construction shall be spread or disposed of so that it will not interfere with waterway functioning.
5. Stabilization
Applicable vegetative standards shall be followed for time of seeding, sprigging or sodding, liming and fertilizing, and site and seedbed preparation.
Erosion control blankets or matting or sod shall be used to aid in the establishment of vegetation. Installation methods should follow manufacturer recommendations. Refer to specification Ds4 - Disturbed Area Stabilization (With Sodding) and Mb - Erosion Control Matting and Blankets.
Mulching shall be a requirement for all seeded or sprigged channels.

Temporary protection during establishment should be provided when conditions permit through temporary diversions or other means to dispose of water.

GaSWCC (Amended - 2000)

6-193

T

T = design top width

D = design depth

D/2

Both values include allowance for

the vegetative lining.

D/4 0.5T 0.75T
PARABOLIC CROSS SECTION

B = design bottom width

z

d = design depth

I

D = design depth plus allowance

for vegetative lining

t = design top width

T = design top width plus allowance

for vegetative lining

z = side slope ratio

T t
B T = B + 2 (zd)
TRAPEZOIDAL CROSS SECTION

D dD

Figure 6-27.1 - Typical Waterway Cross Section

6-194

GaSWCC (Amended - 2000)

6721(&(17(5:$7(5:$<6

:

G



WR



*5$9(/%('',1*

:DWHUZD\ZLWKVWRQHFHQWHUGUDLQ 9VHFWLRQVKDSHGE\PRWRUSDWURO

: :

G

WR





*5$9(/%('',1*

:DWHUZD\ZLWKVWRQHFHQWHUGUDLQ 5RXQGHGVHFWLRQVKDSHGE\EXOOGR]HU

Figure 6-27.2 - Waterway With Stone Center

GaSWCC (Amended - 2000)

6-195

Table 6-27.2 - Velocity, Top Width and Depth for Parabolic Stone Center Waterways

Grade V D
Q
20 25 30 35 40 45 50 55 60 65 70 75 80 90 100 110 120 130 140 150 160 170 180 190 200 220 240 280 280 300

6 Percent

8.0

10

1.3

1.6

6

7

7

8

9

9

10

7

11

7

12

8

13

9

14

10

16

11

17

11

19

12

20

13

22

14

23

15

25

16

26

17

27

18

29

19

32

21

35

23

38

25

40

27

43

29

8 Percent

8.0

10

1.1

1.3

5

6

7

8

9

6

9

6

10

7

11

7

12

8

13

9

14

9

15

10

17

11

19

13

21

14

22

15

24

16

26

17

27

18

29

19

31

20

32

22

34

23

38

25

41

27

44

30

48

32

51

34

10 Percent

8.0 10.0

1.0

1.2

Top Widths

5

6

7

8

5

9

6

10

7

11

7

12

8

12

9

13

9

14

10

15

10

17

12

19

13

21

14

23

16

25

17

27

18

29

20

31

21

33

22

34

23

36

25

38

26

42

29

46

31

50

34

54

36

57

39

12 Percent

8.0 10.0

0.9

1.1

5

6

7

8

5

9

6

10

6

11

7

12

8

13

8

14

9

15

10

16

10

18

11

20

13

22

14

24

15

26

17

29

18

31

19

33

21

35

22

37

24

39

25

42

26

44

28

48

31

53

33

57

36

61

39

66

42

15 Percent

8.0

10.0

0.8

0.9

5

6

4

7

5

8

6

10

7

11

7

12

8

13

9

14

9

16

11

17

11

18

12

19

13

21

15

24

16

26

18

29

20

31

21

33

23

36

24

38

26

40

28

43

29

45

31

47

33

52

38

57

39

62

42

67

45

71

49

6-196

GaSWCC (Amended - 2000)

Table 6-27.3 - Determination of Rock Size For Stone Center Waterway

Design Depth "d" in Feet
3.0

Max. Size - "D"75 75% of the Rock
in Inches 100.0

Slope "S" of Drain
in %
20.0

2.5
2.0
1.5
d = 1.0 ft 1.0 0.9 0.8 0.7 0.6 0.5

50.0

15.0

40.0

30.0

10.0

20.0

15.0

10.0

S = 5.0% 5.0

D75 = 7.9 in.

4.0

5.0

4.0

3.0

3.0

2.0

2.0

1.5 1.0

0.4

1.0

0.5

0.4

0.3

0.3

0.2

0.5

0.4

0.2

0.1

0.3

EXAMPLE: "d" = 1.0 Feet "S" = 5% Place straight edge at "d" value in Design Depth column and at "S" value in Slope column. Read rock size in middle column 7.9 inches. Say 8 inches.

FOR DESIGN: 25% of the rock by volumes should be in sizes of 8 inches or slightly larger. The remaining 75% or less should be of well graded material, smaller than 8 inches, including sufficient sands and gravels to fill the voids between the larger rock.

GaSWCC (Amended - 2000)

6-197

STORMWATER CONVEYANCE CHANNEL DESIGN SHEET
Vegetated Parabolic Channel
EXAMPLE
Computed by__________ Date ______ Checked by___________ Date ______
Project Name___________________________
1. Compute peak rate of runoff for 25-year, 24-hour storm. Q25 = 55 cfs
2. Determine grade of channel. Grade = 6%
3. Determine which vegetative cover will be used. Refer to Ds3 - Disturbed Area Stabilization (Using Permanent Vegetation). Vegetative cover = Bermudagrass
4. Determine retardances and permissible velocities for channel using Table 6-27.1. The retardance class for capacity (unmowed vegetation) is B. The retardance class for stability (mowed vegetation) is D. Maximum permissible velocity, V1, is 5 fps.
5. Determine dimensions of the parabolic channel. Use Table 6-28.1, for retardances "D" and "B". For a grade of 6% and a Q25 of 55 cfs, Top width, T = 29.1 ft (includes allowance for vegetative lining) Depth, D = 1.0 ft (includes allowance for vegetative lining) Velocity for unmowed vegetation, V2 = 2.8 fps.

Normal Ground Level

Parabolic Channel
Example
Top width = 29 ft

Depth of flow
= 1.0 ft

Freeboard = 0.5 ft Grass Lining

6-198

GaSWCC (Amended - 2000)

STORMWATER CONVEYANCE CHANNEL DESIGN SHEET
Vegetated Parabolic Channel
Computed by__________ Date ______ Checked by___________ Date ______
Project Name___________________________
1. Compute peak rate of runoff for 25-year, 24-hour storm. Q25 = _________ cfs
2. Determine grade of channel. Grade = _________ %
3. Determine which vegetative cover will be used. Refer to Ds3 - Disturbed Area Stabilization (Using Permanent Vegetation). Vegetative cover = ____________________
4. Determine retardances and permissible velocities for channel using Table 6-27.1. The retardance class for capacity (unmowed vegetation) is ________. The retardance class for stability (mowed vegetation) is ________. Maximum permissible velocity, V1, is _________ fps.
5. Determine dimensions of the parabolic channel. Use Table 6-28.1 for retardances "D" and "B". Use Table 6-28.2 for retardance "D" and "C". For a grade of ________ % and a Q25 of _________ cfs, Top width, T = _________ ft (includes allowance for vegetative lining) Depth, D = _________ ft (includes allowance for vegetative lining) Velocity for unmowed vegetation, V2 = _________ fps.

Normal Ground Level

Parabolic
Top width= ft

Depth of flow = ft

Freeboard=

ft

Lining

GaSWCC (Amended - 2000)

6-199

STORMWATER CONVEYANCE CHANNEL DESIGN SHEET

Vegetated Trapezoidal or Triangular Channel

Project Name___________________________

Computed by__________ Date ______ Checked by___________ Date ______

1. Compute peak rate of runoff for 25-year, 24-hour storm. Q = _________ cfs
25
2. Determine grade of channel. Grade = _________ %
3. Determine which vegetative cover will be used. Refer to Ds3 - Disturbed Area Stabilization (Using Permanent Vegetation). Vegetative cover = ____________________
4. Determine retardances and permissible velocities for channel using Table 6-27.1. The retardance class for capacity is ________ and the unmowed plant height is ________ in. The retardance class for stability is ________ and the mowed plant height is ________ in. Maximum permissible velocity, V1, is _________ fps.
5. Determine dimensions of the channel. Use Table 6-28.3 for retardance "D". Use Table 6-28.4 for retardance "C". For a grade of ________ % and Q25 of _________ cfs, Side slopes (z:1) = _________ Bottom width, B = _________ ft (0 for triangular channel) Design depth, d = _________ ft Area of channel, A = _________ sf.
6. Calculate the constructed depth of the channel. Constructed depth, D = Design depth, d + Unmowed plant height Constructed depth, D = ________ ft + ________ ft Constructed depth, D = _________ ft
7. Calculate the top width of the channel. Top width, T = Bottom width + 2(Side slope * design depth) Top width, T = B + 2(z*d) Top width, T = _________ ft + 2(______*_________ft) Top width, T = _________ ft

Trapezoidal
Top width= ft

Normal Ground Level

Sideslope = :1

Depth of flow = ft

Freeboard= ft

Sideslope = :1

Lining

Triangular

Top width= ft

Normal Ground Level
6-200

Sideslope = :1

Depth of flow = ft
Sideslope = :1

Freeboard=

ft

Lining GaSWCC (Amended - 2000)

TO BE SUBMITTED WITH/ON THE EROSION AND SEDIMENT CONTROL PLAN
GRASS-LINED CHANNEL 1. Stormwater Conveyance Channel Design Sheet for the appropriate channel shape. 2. Cross-sectional detail of the channel (include with Design Sheet and show on E&SC plan). STONE CENTER CHANNEL 1. Cross-sectional detail of the channel on the E&SC plan.

GaSWCC (Amended - 2000)

6-201

6-202

GaSWCC (Amended - 2000)

SECTION IV: TABLES FOR DESIGN OF STORMWATER CONVEYANCE PRACTICES

GaSWCC (Amended - 2000)

6-203

6-204

GaSWCC (Amended - 2000)

6-205

GaSWCC (Amended - 2000)

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

Table 6-28.1. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "B" Grade 0.25 Percent

V1=2.0 T D V2

V1=2.5 T D V2

V1=3.0 T D V2

V1=3.5 T D V2

V1=4.0 T D V2

V1=4.5 T D V2

V1=5.0 T D V2

V1=5.5 T D V2

V1=6.0 T D V2

11.0 3.2 1.1 13.8 3.0 1.1 16.4 2.9 1.1 19.0 2.8 1.1 21.5 2.8 1.1 11.9 3.7 1.5 24.0 2.8 1.1 14.1 3.4 1.5 26.5 2.8 1.1 15.8 3.3 1.6 29.0 2.8 1.1 17.5 3.3 1.6 31.5 2.7 1.1 19.2 3.2 1.6 11.8 4.4 1.9 34.0 2.7 1.1 20.8 3.2 1.6 13.7 4.0 1.9 37.0 2.7 1.1 22.4 3.2 1.6 15.3 3.8 1.9 39.4 2.7 1.1 24.1 3.2 1.6 16.6 3.7 1.9 41.9 2.7 1.1 25.7 3.1 1.6 17.9 3.7 1.9 44.3 2.7 1.1 27.2 3.1 1.6 19.1 3.6 1.9 46.7 2.7 1.1 28.8 3.1 1.6 20.3 3.6 2.0 49.2 2.7 1.1 30.4 3.1 1.6 21.5 3.6 2.0 51.6 2.7 1.1 32.0 3.1 1.6 22.7 3.5 2.0 54.1 2.7 1.1 33.6 3.1 1.6 23.9 3.5 2.0 14.4 4.8 2.4 56.5 2.7 1.1 35.1 3.1 1.6 25.1 3.5 2.0 15.7 4.6 2.4 59.0 2.7 1.1 36.7 3.1 1.6 26.2 3.5 2.0 17.0 4.4 2.4 61.4 2.7 1.1 38.3 3.1 1.6 27.3 3.5 2.0 17.9 4.3 2.4 63.9 2.7 1.1 39.7 3.1 1.6 28.5 3.4 2.0 18.8 4.3 2.4 66.3 2.7 1.1 41.3 3.1 1.6 29.7 3.4 2.0 19.7 4.2 2.4 68.8 2.7 1.1 43.4 3.0 1.6 30.8 3.4 2.0 20.6 4.2 2.4 71.2 2.7 1.1 44.9 3.0 1.6 32.0 3.4 2.0 21.5 4.1 2.4 73.7 2.7 1.1 46.5 3.0 1.6 33.1 3.4 2.0 22.4 4.1 2.5

T
D
T = Top width, tall vegetation D = Depth, tall vegetation V2 = Design velocity, tall vegetation V1 = Permissible velocity, short vegetation

RETARDANCE "D" AND "B"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

6-206

Table 6-28.1. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "B" Grade 0.50 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0 T D V2

V1=2.5 T D V2

V1=3.0 T D V2

V1=3.5 T D V2

V1=4.0 T D V2

V1=4.5 T D V2

V1=5.0 T D V2

V1=5.5 T D V2

10.0 2.2 1.0 13.7 2.1 1.0 8.4 2.7 1.3 17.4 2.1 1.0 11.3 2.4 1.4 21.0 2.0 1.0 13.9 2.3 1.4 24.6 2.0 1.1 16.4 2.3 1.4 10.7 2.8 1.8 28.5 2.0 1.0 18.9 2.3 1.4 12.6 2.7 1.8 31.9 2.0 1.1 21.4 2.3 1.4 14.4 2.6 1.8 35.5 2.0 1.1 23.9 2.2 1.4 16.2 2.5 1.8 9.9 3.4 2.2 39.0 2.0 1.1 26.3 2.2 1.4 17.9 2.5 1.8 11.9 3.1 2.3 42.5 2.0 1.1 28.8 2.2 1.4 19.7 2.5 1.8 13.2 3.0 2.3 46.1 2.0 1.1 31.6 2.2 1.4 21.4 2.5 1.8 14.5 2.9 2.3 49.6 2.0 1.1 34.0 2.2 1.4 23.1 2.5 1.8 15.8 2.9 2.3 11.0 3.6 2.6 53.1 2.0 1.1 36.4 2.2 1.4 24.9 2.5 1.8 17.1 2.8 2.3 12.7 3.4 2.7 56.6 2.0 1.1 38.8 2.2 1.4 26.6 2.5 1.8 18.4 2.8 2.3 13.7 3.3 2.7 60.2 2.0 1.1 41.2 2.2 1.4 28.3 2.5 1.8 19.7 2.8 2.3 14.8 3.2 2.7 63.7 2.0 1.1 43.6 2.2 1.4 30.0 2.4 1.8 20.9 2.8 2.3 15.9 3.2 2.7 67.2 2.0 1.1 46.1 2.2 1.4 31.7 2.4 1.8 22.1 2.8 2.3 16.9 3.1 2.7 70.8 2.0 1.1 48.5 2.2 1.4 33.7 2.4 1.8 23.4 2.8 2.3 17.9 3.1 2.7 12.3 3.9 3.1 74.3 2.0 1.1 50.9 2.2 1.4 35.4 2.4 1.8 24.5 2.7 2.4 18.9 3.1 2.7 13.7 3.7 3.1 77.8 2.0 1.1 53.3 2.2 1.4 37.1 2.4 1.8 25.8 2.7 2.4 19.9 3.1 2.7 14.6 3.6 3.1 81.4 2.0 1.1 55.7 2.2 1.4 38.7 2.4 1.8 27.0 2.7 2.4 20.8 3.0 2.7 15.4 3.6 3.1 84.9 2.0 1.1 58.1 2.2 1.4 40.4 2.4 1.9 28.2 2.7 2.4 21.8 3.0 2.7 16.3 3.5 3.1 88.4 2.0 1.1 60.6 2.2 1.4 42.1 2.4 1.9 29.4 2.7 2.4 22.8 3.0 2.7 17.1 3.5 3.1 92.0 2.0 1.1 63.0 2.2 1.4 43.8 2.4 1.9 30.6 2.7 2.4 23.8 3.0 2.7 17.9 3.5 3.1 95.5 2.0 1.1 65.4 2.2 1.4 45.4 2.4 1.9 31.8 2.7 2.4 24.8 3.0 2.7 18.7 3.4 3.2 99.0 2.0 1.1 67.8 2.2 1.4 47.1 2.4 1.9 33.1 2.7 2.4 25.7 3.0 2.8 19.4 3.4 3.2 102.6 2.0 1.1 70.2 2.2 1.4 48.8 2.4 1.9 34.3 2.7 2.4 26.7 3.0 2.8 20.2 3.4 3.2 13.5 4.4 3.6 106.1 2.0 1.1 72.6 2.2 1.4 50.5 2.4 1.9 35.5 2.7 2.4 27.7 3.0 2.8 21.0 3.4 3.2 14.4 4.3 3.6

V1=6.0 T D V2

GaSWCC (Amended - 2000)

RETARDANCE "D" AND "B"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

GaSWCC (Amended - 2000)

Table 6-28.1. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "B" Grade 0.75 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0 T D V2

V1=2.5 T D V2

V1=3.0 T D V2

V1=3.5 T D V2

V1=4.0 T D V2

V1=4.5 T D V2

V1=5.0 T D V2

V1=5.5 T D V2

V1=6.0 T D V2

8.3 1.9 1.0 12.9 1.8 1.0 8.4 2.1 1.3 17.4 1.7 1.0 11.6 2.0 1.3 7.2 2.6 1.6 22.2 1.7 1.0 14.8 1.9 1.3 10.0 2.2 1.7 26.6 1.7 1.0 17.9 1.9 1.3 12.3 2.1 1.7 7.7 2.9 2.0 31.0 1.7 1.0 20.9 1.9 1.4 14.5 2.1 1.7 10.0 2.5 2.1 35.4 1.7 1.0 23.9 1.9 1.4 16.7 2.1 1.7 11.8 2.4 2.1 39.8 1.7 1.0 27.3 1.8 1.3 18.9 2.1 1.7 13.5 2.3 2.2 8.9 3.0 2.6 44.2 1.7 1.0 30.3 1.8 1.3 21.1 2.0 1.7 15.1 2.3 2.2 10.7 2.7 2.6 48.7 1.7 1.0 33.3 1.8 1.3 23.3 2.0 1.7 16.7 2.3 2.2 12.1 2.6 2.6 53.1 1.7 1.0 36.3 1.8 1.4 25.5 2.0 1.7 18.4 2.3 2.2 13.4 2.6 2.6 57.5 1.7 1.0 39.3 1.8 1.4 28.0 2.0 1.7 20.0 2.2 2.2 14.7 2.5 2.6 9.5 3.3 3.1 61.9 1.7 1.0 42.3 1.8 1.4 30.2 2.0 1.7 21.6 2.2 2.2 15.9 2.5 2.6 11.2 3.0 3.1 66.3 1.7 1.0 45.3 1.8 1.4 32.3 2.0 1.7 23.2 2.2 2.2 17.2 2.5 2.6 12.3 2.9 3.1 70.7 1.7 1.0 48.3 1.8 1.4 34.4 2.0 1.7 24.8 2.2 2.2 18.4 2.5 2.6 13.3 2.9 3.1 75.2 1.7 1.0 51.4 1.8 1.4 36.6 2.0 1.7 26.3 2.2 2.2 19.6 2.5 2.6 14.3 2.8 3.1 10.2 3.6 3.4 79.6 1.7 1.0 54.4 1.8 1.4 38.7 2.0 1.7 27.9 2.2 2.2 20.8 2.4 2.7 15.3 2.8 3.1 11.4 3.4 3.5 84.0 1.7 1.0 57.4 1.8 1.4 40.9 2.0 1.7 29.5 2.2 2.2 22.0 2.4 2.7 16.3 2.8 3.1 12.7 3.2 3.5 88.4 1.7 1.0 60.4 1.8 1.4 43.0 2.0 1.7 31.4 2.2 2.2 23.2 2.4 2.7 17.2 2.8 3.1 13.5 3.2 3.5 92.8 1.7 1.0 63.4 1.8 1.4 45.1 2.0 1.7 33.0 2.2 2.2 24.4 2.4 2.7 18.2 2.7 3.2 14.4 3.1 3.5 97.2 1.7 1.0 66.4 1.8 1.4 47.3 2.0 1.7 34.6 2.2 2.2 25.6 2.4 2.7 19.1 2.7 3.2 15.2 3.1 3.5 101.7 1.7 1.0 69.4 1.8 1.4 49.4 2.0 1.7 36.1 2.2 2.2 26.8 2.4 2.7 20.0 2.7 3.2 16.0 3.0 3.5 11.6 3.8 3.9 106.1 1.7 1.0 72.5 1.8 1.4 51.6 2.0 1.7 37.7 2.2 2.2 28.0 2.4 2.7 21.0 2.7 3.2 16.8 3.0 3.5 12.6 3.6 3.9 110.5 1.7 1.0 75.5 1.8 1.4 53.7 2.0 1.7 39.2 2.2 2.2 29.2 2.4 2.7 21.9 2.7 3.2 17.6 3.0 3.5 13.7 3.5 3.9 114.9 1.7 1.0 78.5 1.8 1.4 55.8 2.0 1.7 40.8 2.2 2.2 30.4 2.4 2.7 22.8 2.7 3.2 18.4 3.0 3.6 14.4 3.4 3.9 119.3 1.7 1.0 81.5 1.8 1.4 58.0 2.0 1.7 42.4 2.2 2.2 31.6 2.4 2.7 23.8 2.7 3.2 19.1 2.9 3.6 15.1 3.4 4.0 123.7 1.7 1.0 84.5 1.8 1.4 60.1 2.0 1.7 43.9 2.2 2.2 32.8 2.4 2.7 24.7 2.7 3.2 19.9 2.9 3.6 15.8 3.4 4.0 128.2 1.7 1.0 87.5 1.8 1.4 62.3 2.0 1.7 45.5 2.2 2.2 34.5 2.4 2.7 25.6 2.7 3.2 20.7 2.9 3.6 16.5 3.3 4.0 132.6 1.7 1.0 90.6 1.8 1.4 64.4 2.0 1.7 47.1 2.2 2.2 35.7 2.4 2.7 26.5 2.6 3.2 21.5 2.9 3.6 17.1 3.3 4.0

6-207

RETARDANCE "D" AND "B"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

6-208

Table 6-28.1. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "B" Grade 1.00 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0 T D V2

V1=2.5 T D V2

V1=3.0 T D V2

V1=3.5 T D V2

V1=4.0 T D V2

V1=4.5 T D V2

V1=5.0 T D V2

V1=5.5 T D V2

V1=6.0 T D V2

9.7 1.6 1.0 6.2 2.0 1.2 14.8 1.5 1.0 10.2 1.7 1.3 6.5 2.2 1.5 20.2 1.5 1.0 13.8 1.7 1.3 9.6 1.9 1.6 25.1 1.5 1.0 17.4 1.7 1.3 12.2 1.9 1.6 8.5 2.2 2.0 30.1 1.5 1.0 21.0 1.6 1.3 14.9 1.8 1.7 10.6 2.1 2.1 35.1 1.5 1.0 24.7 1.6 1.3 17.5 1.8 1.7 12.6 2.0 2.1 8.9 2.4 2.5 40.1 1.5 1.0 28.2 1.6 1.3 20.0 1.8 1.7 14.5 2.0 2.1 10.5 2.3 2.5 45.1 1.5 1.0 31.7 1.6 1.3 22.5 1.8 1.7 16.4 2.0 2.1 12.1 2.2 2.5 8.2 2.8 2.9 50.2 1.5 1.0 35.2 1.6 1.3 25.4 1.8 1.7 18.3 2.0 2.1 13.6 2.2 2.5 10.0 2.6 2.9 55.2 1.5 1.0 38.8 1.6 1.3 27.9 1.8 1.7 20.3 1.9 2.1 15.1 2.2 2.5 11.2 2.5 3.0 60.2 1.5 1.0 42.3 1.6 1.3 30.4 1.8 1.7 22.2 1.9 2.1 16.6 2.1 2.5 12.4 2.4 3.0 65.2 1.5 1.0 45.8 1.6 1.3 32.9 1.8 1.7 24.0 1.9 2.1 18.0 2.1 2.5 13.6 2.4 3.0 8.9 3.1 3.5 70.2 1.5 1.0 49.3 1.6 1.3 35.5 1.8 1.7 25.9 1.9 2.1 19.5 2.1 2.6 14.8 2.4 3.0 10.6 2.8 3.5 75.2 1.5 1.0 52.8 1.6 1.3 38.0 1.8 1.7 28.2 1.9 2.1 20.9 2.1 2.6 16.0 2.3 3.0 11.5 2.8 3.5 80.2 1.5 1.0 56.3 1.6 1.3 40.5 1.8 1.7 30.0 1.9 2.1 22.3 2.1 2.6 17.1 2.3 3.0 12.5 2.7 3.5 85.2 1.5 1.0 59.8 1.6 1.3 43.0 1.8 1.7 31.9 1.9 2.1 23.7 2.1 2.6 18.3 2.3 3.0 13.5 2.7 3.6 9.8 3.3 3.9 90.2 1.5 1.0 63.3 1.6 1.3 45.6 1.8 1.7 33.6 1.9 2.1 25.2 2.1 2.6 19.4 2.3 3.1 14.4 2.6 3.6 10.9 3.1 3.9 95.2 1.5 1.0 66.9 1.6 1.3 48.1 1.8 1.7 35.5 1.9 2.1 26.6 2.1 2.6 20.5 2.3 3.1 15.3 2.6 3.6 12.0 3.0 3.9 100.2 1.5 1.0 70.4 1.6 1.3 50.6 1.8 1.7 37.4 1.9 2.1 28.0 2.1 2.6 21.6 2.3 3.1 16.2 2.6 3.6 12.9 2.9 4.0 105.3 1.5 1.0 73.9 1.6 1.3 53.1 1.8 1.7 39.2 1.9 2.1 29.8 2.1 2.6 22.8 2.3 3.1 17.1 2.6 3.6 13.7 2.9 4.0 10.8 3.4 4.3 110.3 1.5 1.0 77.4 1.6 1.3 55.7 1.8 1.7 41.1 1.9 2.1 31.3 2.1 2.6 23.9 2.3 3.1 18.0 2.6 3.6 14.4 2.9 4.0 12.0 3.2 4.3 115.3 1.5 1.0 80.9 1.6 1.3 58.2 1.8 1.7 42.9 1.9 2.1 32.7 2.1 2.6 25.0 2.3 3.1 18.9 2.5 3.6 15.2 2.8 4.0 12.7 3.2 4.3 120.3 1.5 1.0 84.4 1.6 1.3 60.7 1.8 1.7 44.8 1.9 2.1 34.1 2.1 2.6 26.1 2.2 3.1 19.7 2.5 3.6 16.0 2.8 4.0 13.4 3.1 4.3 125.3 1.5 1.0 88.0 1.6 1.3 63.2 1.8 1.7 46.7 1.9 2.1 35.5 2.1 2.6 27.2 2.2 3.1 20.6 2.5 3.6 16.8 2.8 4.0 14.1 3.1 4.3 130.3 1.5 1.0 91.5 1.6 1.3 65.8 1.8 1.7 48.5 1.9 2.1 36.9 2.1 2.6 28.4 2.2 3.1 21.5 2.5 3.6 17.4 2.8 4.0 14.8 3.1 4.3 135.3 1.5 1.0 95.0 1.6 1.3 68.3 1.8 1.7 50.4 1.9 2.1 38.3 2.1 2.6 29.5 2.2 3.1 22.4 2.5 3.6 18.2 2.8 4.0 15.5 3.0 4.3 140.3 1.5 1.0 98.5 1.6 1.3 70.8 1.8 1.7 52.2 1.9 2.1 39.7 2.0 2.6 30.6 2.2 3.1 23.2 2.5 3.6 18.9 2.7 4.0 16.1 3.0 4.4 145.3 1.5 1.0 102.0 1.6 1.3 73.3 1.8 1.7 54.1 1.9 2.1 41.1 2.0 2.6 32.1 2.2 3.0 24.1 2.5 3.6 19.7 2.7 4.0 16.8 3.0 4.4 150.3 1.5 1.0 105.5 1.6 1.3 75.9 1.8 1.7 56.0 1.9 2.1 42.5 2.0 2.6 33.2 2.2 3.0 25.0 2.5 3.6 20.4 2.7 4.1 17.5 2.9 4.4

GaSWCC (Amended - 2000)

RETARDANCE "D" AND "B"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

GaSWCC (Amended - 2000)

Table 6-28.1. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "B" Grade 1.25 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

T D V2 T D V2 5.0 1.8 0.8 11.1 1.4 0.9 7.4 1.6 1.2 16.9 1.4 1.0 11.6 1.5 1.3 22.8 1.4 0.9 15.6 1.5 1.3 28.4 1.4 1.0 19.9 1.5 1.3 34.1 1.4 1.0 23.8 1.5 1.3 39.8 1.4 1.0 27.8 1.5 1.3 45.4 1.4 1.0 31.7 1.5 1.3 51.1 1.4 1.0 35.6 1.5 1.3 56.8 1.4 1.0 39.5 1.5 1.3 62.5 1.4 1.0 43.5 1.5 1.3 68.1 1.4 1.0 47.4 1.5 1.3 73.8 1.4 1.0 51.4 1.5 1.3 79.5 1.4 1.0 55.3 1 5 1.3 85.2 1.4 1.0 59.2 1.5 1.3 90.8 1.4 1.0 63.2 1.5 1.3 96.5 1.4 1.0 67.1 1.5 1.3 102.2 1.4 1.0 71.1 1.5 1.3 107.9 1.4 1.0 75.0 1.5 1.3 113.5 1.4 1.0 79.0 1.5 1.3 119.2 1.4 1.0 82.9 1.5 1.3 124.9 1.4 1.0 86.9 1.5 1.3 130.6 1.4 1.0 90.8 1.5 1.3 136.2 1.4 1.0 94.8 1.5 1.3 141.9 1.4 1.0 98.7 1.5 1.3 147.6 1.4 1.0 102.7 1.5 1.3 153.3 1.4 1.0 106.6 1.5 1.3 158.9 1.4 1.0 110.5 1.5 1.3 164.6 1.4 1.0 114.5 1.5 1.3 170.3 1.4 1.0 118.4 1.5 1.3

V1=3.0 T D V2
8.1 1.8 1.6 11.1 1.7 1.6 14.1 1.7 1.6 17.0 1.6 1.6 19.8 1.6 1.6 23.0 1.6 1.6 25.8 1.6 1.6 28.7 1.6 1.6 31.5 1.6 1.6 34.4 1.6 1.6 37.2 1.6 1.6 40.1 1.6 1.6 43.0 1.6 1.6 45.8 1.6 1.6 48.7 1.6 1.6 51.5 1.6 1.6 54.4 1.6 1.6 57.2 1.6 1.6 60.1 1.6 1.6 63.0 1.6 1.6 65.8 1.6 1.6 68.7 1.6 1.6 71.5 1.6 1.6 74.4 1.6 1.6 77.3 1.6 1.6 80.1 1.6 1.6 83.0 1.6 1.6 85.8 1.6 1.6

V1=3.5 T D V2
7.8 2.0 1.9 10.1 1.9 2.0 12.4 1.8 2.0 14.6 1.8 2.0 16.8 1.8 2.0 19.0 1.8 2.0 21.1 1.7 2.0 23.6 1.7 2.0 25.7 1.7 2.0 27.9 1.7 2.0 30.0 1.7 2.0 32.1 1.7 2.0 34.2 1.7 2.0 36.4 1.7 2.0 38.5 1.7 2.0 40.6 1.7 2.0 42.8 1.7 2.0 44.9 1.7 2.0 47.0 1.7 2.0 49.2 1.7 2.0 51.3 1.7 2.0 53.4 1.7 2.0 55.6 1.7 2.0 57.7 1.7 2.0 59.8 1.7 2.0 62.0 1.7 2.0 64.1 1.7 2.0

V1=4.0 T D V2
6.8 2.4 2.3 9.0 2.1 2.4 10.8 2.0 2.4 12.5 2.0 2.5 14.2 1.9 2.5 15.9 1.9 2.5 17.6 1.9 2.5 19.2 1.9 2.5 20.9 1.9 2.5 22.5 1.9 2.5 24.1 1.9 2.5 26.1 1.9 2.5 27.7 1.8 2.5 29.3 1.8 2.5 30.9 1.8 2.5 32.6 1.8 2.5 34.2 1.8 2.5 35.8 1.8 2.5 37.4 1.8 2.5 39.0 1.8 2.5 40.6 1.8 2.5 42.3 1.8 2.5 43.9 1.8 2.5 45.5 1.8 2.5 47.1 1.8 2.5 48.8 1.8 2.5

V1=4.5 T D V2
7.4 2.5 2.8 9.3 2.3 2.9 10.7 2.2 2.9 12.1 2.1 2.9 13.4 2.1 2.9 14.7 2.1 2.9 16.1 2.1 2.9 17.4 2.1 2.9 18.6 2.0 3.0 19.9 2.0 3.0 21.2 2.0 3.0 22.5 2.0 3.0 23.8 2.0 3.0 25.1 2.0 3.0 26.4 2.0 3.0 27.6 2.0 3.0 29.3 2.0 3.0 30.5 2.0 3.0 31.8 2.0 3.0 33.1 2.0 3.0 34.3 2.0 3.0 35.6 2.0 3.0 36.9 2.0 3.0 38.1 2.0 3.0

V1=5.0 T D V2
8.7 2.6 3.3 10.2 2.4 3.4 11.3 2.4 3.4 12.4 2.3 3.4 13.5 2.3 3.4 14.6 2.3 3.4 15.7 2.2 3.4 16.7 2.2 3.4 17.7 2.2 3.5 18.8 2.2 3.5 19.8 2.2 3.5 20.8 2.2 3.5 21.9 2.2 3.5 22.9 2.2 3.5 23.9 2.2 3.5 25.0 2.2 3.5 26.0 2.2 3.5 27.0 2.2 3.5 28.0 2.2 3.5 29.1 2.2 3.5 30.1 2.2 3.5

V1=5.5 T D V2
9.0 2.9 3.8 10.3 2.7 3.8 11.3 2.6 3.8 12.2 2.5 3.9 13.1 2.5 3.9 14.0 2.5 3.9 14.9 2.5 3.9 15.8 2.4 3.9 16.6 2.4 3.9 17.5 2.4 3.9 18.3 2.4 3.9 19.2 2.4 3.9 20.0 2.4 3.9 20.9 2.4 3.9 21.7 2.4 3.9 22.6 2.4 3.9 23.4 2.4 3.9 24.3 2.3 4.0

V1=6.0 T D V2
10.1 3.1 4.4 11.3 2.9 4.4 12.1 2.8 4.4 12.8 2.8 4.4 13.6 2.8 4.4 14.3 2.7 4.4 15.0 2.7 4.4 15.8 2.7 4.4 16.4 2.7 4.5 17.1 2.6 4.5 17.8 2.6 4.5 18.5 2.6 4.5 19.2 2.6 4.5

6-209

RETARDANCE "D" AND "B"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

6-210

Table 6-28.1. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "B" Grade 1.50 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

T D V2 T D V2 5.9 1.5 0.9 12.4 1.3 0.9 8.3 1.5 1.2 18.9 1.3 0.9 12.8 1.4 1.2 25.1 1.3 0.9 17.2 1.4 1.2 31.4 1.3 0.9 21.8 1.4 1.2 37.7 1.3 0.9 26.1 1.4 1.2 43.9 1.3 0.9 30.4 1.4 1.2 50.2 1.3 0.9 34.8 1.4 1.3 56.5 1.3 0.9 39.1 1.4 1.3 62.7 1.3 0.9 43.5 1.4 1.3 69.0 1.3 0.9 47.8 1.4 1.3 75.3 1.3 0.9 52.1 1.4 1.3 81.5 1.3 0.9 56.5 1.4 1.3 87.8 1.3 0.9 60.8 1.4 1.3 94.1 1.3 0.9 65.2 1.4 1.3 100.3 1.3 0.9 69.5 1.4 1.3 106.6 1.3 0.9 73.8 1.4 1.3 112.9 1.3 0.9 78.2 1.4 1.3 119.1 1.3 0.9 82.5 1.4 1.3 125.4 1.3 0.9 86.9 1.4 1.3 131.7 1.3 0.9 91.2 1.4 1.3 138.0 1.3 0.9 95.5 1.4 1.3 144.2 1.3 0.9 99.9 1.4 1.3 150.5 1.3 0.9 104.2 1.4 1.3 156.8 1.3 0.9 108.6 1.4 1.3 163.0 1.3 0.9 112.9 1.4 1.3 169.3 1.3 0.9 117.2 1.4 1.3 175.6 1.3 0.9 121.6 1.4 1.3 181.8 1.3 0.9 125.9 1.4 1.3 188.1 1.3 0.9 130.3 1.4 1.3

V1=3.0
T D V2
5.5 1.9 1.5 9.1 1.6 1.6 12.4 1.5 1.6 15.6 1.5 1.6 18.8 1.5 1.6 22.2 1.5 1.6 25.3 1.5 1.6 28.5 1.5 1.6 31.7 1.5 1.6 34.8 1.5 1.6 38.0 1.5 1.6 41.1 1.5 1.6 44.3 1.5 1.6 47.4 1.5 1.6 50.6 1.5 1.6 53.7 1.5 1.6 56.9 1.5 1.6 60.0 1.5 1.6 63.2 1.5 1.6 66.4 1.5 1.6 69.5 1.5 1.6 72.7 1.5 1.6 75.8 1.5 1.6 79.0 1.5 1.6 82.2 1.5 1.6 85.3 1.5 1.6 88.5 1.5 1.6 91.6 1.5 1.6 94.8 1.5 1.6

V1=3.5 T D V2
6.2 1.9 1.9 9.0 1.7 1.9 11.5 1.7 2.0 14.0 1.6 2.0 16.4 1.6 2.0 18.8 1.6 2.0 21.2 1.6 2.0 23.9 1.6 2.0 26.2 1.6 2.0 28.6 1.6 2.0 31.0 1.6 2.0 33.3 1.6 2.0 35.7 1.6 2.0 38.1 1.6 2.0 40.5 1.6 2.0 42.8 1.6 2.0 45.2 1.6 2.0 47.6 1.6 2.0 50.0 1.6 2.0 52.3 1.6 2.0 54.7 1.6 2.0 57.1 1.6 2.0 59.5 1.6 2.0 61.8 1.6 2.0 64.2 1.6 2.0 66.6 1.6 2.0 69.0 1.6 2.0 71.3 1.6 2.0

V1=4.0 T D V2
6.0 2.2 2.2 8.4 1.9 2.4 10.4 1.8 2.4 12.3 1.8 2.4 14.2 1.8 2.4 16.1 1.7 2.4 17.9 1.7 2.4 19.8 1.7 2.4 21.6 1.7 2.4 23.8 1.7 2.4 25.6 1.7 2.4 27.4 1.7 2.4 29.1 1.7 2.4 30.9 1.7 2.4 32.7 1.7 2.4 34.5 1.7 2.4 36.3 1.7 2.4 38.1 1.7 2.4 40.0 1.7 2.4 41.8 1.7 2.4 43.6 1.7 2.4 45.4 1.7 2.4 47.2 1.7 2.4 49.0 1.7 2.4 50.8 1.7 2.4 52.6 1.7 2.4 54.4 1.7 2.4

V1=4.5 T D V2
7.6 2.1 2.8 9.2 2.0 2.8 10.8 2.0 2.8 12.3 1.9 2.9 13.8 1.9 2.9 15.3 1.9 2.9 16.7 1.9 2.9 18.2 1.9 2.9 19.6 1.8 2.9 21.0 1.8 2.9 22.5 1.8 2.9 23.9 1.8 2.9 25.7 1.8 2.9 27.1 1.8 2.9 28.5 1.8 2.9 29.9 1.8 2.9 31.3 1.8 2.9 32.8 1.8 2.9 34.2 1.8 2.9 35.6 1.8 2.9 37.0 1.8 2.9 38.4 1.8 2.9 39.8 1.8 2.9 41.3 1.8 2.9 42.7 1.8 2.9

V1=5.0 T D V2
7.8 2.4 3.2 9.4 2.2 3.3 10.6 2.1 3.3 11.9 2.1 3.3 13.1 2.1 3.3 14.3 2.0 3.3 15.5 2.0 3.3 16.6 2.0 3.4 17.8 2.0 3.4 18.9 2.0 3.4 20.1 2.0 3.4 21.2 2.0 3.4 22.4 2.0 3.4 23.5 2.0 3.4 24.7 2.0 3.4 25.8 2.0 3.4 27.0 2.0 3.4 28.5 2.0 3.4 29.6 2.0 3.4 30.8 1.9 3.4 31.9 1.9 3.4 33.0 1.9 3.4 34.2 1.9 3.4

V1=5.5 T D V2
9.1 2.4 3.7 10.1 2.4 3.8 11.2 2.3 3.8 12.2 2.3 3.8 13.2 2.2 3.8 14.2 2.2 3.8 15.2 2.2 3.8 16.1 2.2 3.9 17.0 2.2 3.9 18.0 2.2 3.9 19.0 2.1 3.9 19.9 2.1 3.9 20.9 2.1 3.9 21.8 2.1 3.9 22.7 2.1 3.9 23.7 2.1 3.9 24.6 2.1 3.9 25.6 2.1 3.9 26.5 2.1 3.9 27.4 2.1 3.9

V1=6.0 T D V2
9.2 2.7 4.2 10.3 2.6 4.2 11.2 2.5 4.3 12.1 2.5 4.3 12.9 2.4 4.3 13.8 2.4 4.3 14.6 2.4 4.3 15.4 2.4 4.3 16.2 2.3 4.3 17.0 2.3 4.3 17.8 2.3 4.4 18.6 2.3 4.4 19.3 2.3 4.4 20.1 2.3 4.4 20.9 2.3 4.4 21.7 2.3 4.4 22.5 2.3 4.4

GaSWCC (Amended - 2000)

RETARDANCE "D" AND "B"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

GaSWCC (Amended - 2000)

Table 6-28.1. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "B" Grade 1.75 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

V1=3.0

T D V2 T D V2 T D V2 6.5 1.3 0.9 13.5 1.2 0.9 9.1 1.4 1.2 6.4 1.6 1.5 20.5 1.2 0.9 13.9 1.3 1.2 10.0 1.4 1.6 27.3 1.2 0.9 18.8 1.3 1.2 13.6 1.4 1.6 34.1 1.2 0.9 23.5 1.3 1.2 17.0 1.4 1.6 40.9 1.2 0.9 28.2 1.3 1.2 20.7 1.4 1.6 47.7 1.2 0.9 32.8 1.3 1.2 24.1 1.4 1.6 54.5 1.2 0.9 37.5 1.3 1.2 27.5 1.4 1.6 61.3 1.2 0.9 42.2 1.3 1.2 30.9 1.4 1.6 68.1 1.2 0.9 46.9 1.3 1.2 34.4 1.4 1.6 74.9 1.2 0.9 51.6 1.3 1.2 37.8 1.4 1.6 81.7 1.2 0.9 56.2 1.3 1.2 41.2 1.4 1.6 88.5 1.2 0.9 60.9 1.3 1.2 44.6 1.4 1.6 95.4 1.2 0.9 65.6 1.3 1.2 48.1 1.4 1.6 102.2 1.2 0.9 70.3 1.3 1.2 51.5 1.4 1.6 109.0 1.2 0.9 75.0 1.3 1.2 54.9 1.4 1.6 115.8 1.2 0.9 79.6 1.3 1.2 58.3 1.4 1.6 122.6 1.2 0.9 84.3 1.3 1.2 61.8 1.4 1.6 129.4 1.2 0.9 89.0 1.3 1.2 65.2 1.4 1.6 136.2 1.2 0.9 93.7 1.3 1.2 68.6 1.4 1.6 143.0 1.2 0.9 98.4 1.3 1.2 72.1 1.4 1.6 149.8 1.2 0.9 103.1 1.3 1.2 75.5 1.4 1.6 156.6 1.2 0.9 107.7 1.3 1.2 78.9 1.4 1.6 163.4 1.2 0.9 112.4 1.3 1.2 82.3 1.4 1.6 170.3 1.2 0.9 117.1 1.3 1.2 85.8 1.4 1.6 177.1 1.2 0.9 121.8 1.3 1.2 89.2 1.4 1.6 183.9 1.2 0.9 126.5 1.3 1.2 92.6 1.4 1.6 190.7 1.2 0.9 131.2 1.3 1.2 96.1 1.4 1.6 197.5 1.2 0.9 135.8 1.3 1.2 99.5 1.4 1.6 204.3 1.2 0.9 140.5 1.3 1.2 102.9 1.4 1.6

V1=3.5 T D V2
7.2 1.7 1.9 10.0 1.6 1.9 12.7 1.5 1.9 15.4 1.5 1.9 17.9 1.5 2.0 20.8 1.5 1.9 23.4 1.5 1.9 26.0 1.5 1.9 28.5 1.5 1.9 31.1 1.5 2.0 33.7 1.5 2.0 36.3 1.5 2.0 38.9 1.5 2.0 41.5 1.5 2.0 44.1 1.5 2.0 46.6 1.5 2.0 49.2 1.5 2.0 51.8 1.5 2.0 54.4 1.5 2.0 57.0 1.5 2.0 59.6 1.5 2.0 62.2 1.5 2.0 64.8 1.5 2.0 67.3 1.5 2.0 69.9 1.5 2.0 72.5 1.5 2.0 75.1 1.5 2.0 77.7 1.5 2.0

V1=4.0 T D V2
7.3 1.8 2.3 9.5 1.7 2.3 11.6 1.7 2.3 13.6 1.6 2.4 15.7 1.6 2.4 17.7 1.6 2.4 19.7 1.6 2.4 22.1 1.6 2.3 24.0 1.6 2.3 26.0 1.6 2.4 28.0 1.6 2.4 30.0 1.6 2.4 32.0 1.6 2.4 34.0 1.6 2.4 36.0 1.6 2.4 37.9 1.6 2.4 39.8 1.6 2.4 41.8 1.6 2.4 43.8 1.6 2.4 45.8 1.6 2.4 47.8 1.6 2.4 49.8 1.6 2.4 51.8 1.6 2.4 53.8 1.6 2.4 55.7 1.6 2.4 57.7 1.6 2.4 59.7 1.6 2.4

V1=4.5 T D V2
6.8 2.0 2.7 8.7 1.9 2.8 10.4 1.8 2.8 12.1 1.8 2.8 13.7 1.8 2.8 15.3 1.7 2.8 16.9 1.7 2.8 18.5 1.7 2.8 20.1 1.7 2.8 21.6 1.7 2.9 23.2 1.7 2.9 25.1 1.7 2.8 26.6 1.7 2.8 28.2 1.7 2.8 29.8 1.7 2.8 31.3 1.7 2.8 32.9 1.7 2.8 34.4 1.7 2.8 36.0 1.7 2.8 37.6 1.7 2.8 39.1 1.7 2.9 40.7 1.7 2.9 42.2 1.7 2.9 43.8 1.7 2.9 45.3 1.7 2.9 46.9 1.7 2.9

V1=5.0 T D V2
7.9 2.1 3.2 9.3 2.0 3.2 10.7 1.9 3.3 12.0 1.9 3.3 13.3 1.9 3.3 14.6 1.9 3.3 15.9 1.9 3.3 17.2 1.8 3.3 18.4 1.8 3.3 19.7 1.8 3.3 21.0 1.8 3.3 22.2 1.8 3.3 23.5 1.8 3.3 24.8 1.8 3.3 26.4 1.8 3.3 27.6 1.8 3.3 28.9 1.8 3.3 30.1 1.8 3.3 31.4 1.8 3.3 32.6 1.8 3.3 33.9 1.8 3.3 35.1 1.8 3.3 36.4 1.8 3.3 37.6 1.8 3.3

V1=5.5 T D V2
7.9 2.3 3.7 9.3 2.2 3.7 10.5 2.1 3.7 11.6 2.1 3.7 12.7 2.1 3.7 13.8 2.0 3.8 14.8 2.0 3.8 15.8 2.0 3.8 16.9 2.0 3.8 17.9 2.0 3.8 19.0 2.0 3.8 20.0 2.0 3.8 21.1 2.0 3.8 22.1 2.0 3.8 23.1 2.0 3.8 24.2 1.9 3.8 25.2 1.9 3.8 26.2 1.9 3.8 27.3 1.9 3.8 28.7 1.9 3.8 29.7 1.9 3.8 30.7 1.9 3.8

V1=6.0 T D V2
7.5 2.7 4.1 9.0 2.4 4.1 10.0 2.3 4.2 11.0 2.3 4.2 11.9 2.2 4.2 12.8 2.2 4.2 13.7 2.2 4.2 14.6 2.2 4.3 15.5 2.2 4.3 16.3 2.1 4.3 17.2 2.1 4.3 18.1 2.1 4.3 19.0 2.1 4.3 19.8 2.1 4.3 20.7 2.1 4.3 21.5 2.1 4.3 22.4 2.1 4.3 23.3 2.1 4.3 24.1 2.1 4.3 25.0 2.1 4.3

6-211

RETARDANCE "D" AND "B"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

6-212

Table 6-28.1. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "B" Grade 2.00 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

V1=3.0

T D V2 T D V2 T D V2 7.1 1.2 0.9 14.7 1.2 0.9 9.5 1.3 1.2 7.0 1.4 1.5 22.0 1.2 0.9 14.5 1.3 1.2 10.8 1.4 1.5 29.3 1.2 0.9 19.6 1.2 1.2 14.6 1.3 1.5 36.6 1.2 0.9 24.4 1.2 1.2 18.5 1.3 1.5 43.9 1.2 0.9 29.3 1.2 1.2 22.2 1.3 1.6 51.2 1.2 0.9 34.2 1.2 1.2 25.8 1.3 1.6 58.5 1.2 0.9 39.0 1.2 1.2 29.5 1.3 1.6 65.8 1.2 0.9 43.9 1.2 1.2 33.2 1.3 1.6 73.1 1.2 0.9 48.8 1.2 1.2 36.8 1.3 1.6 80.4 1.2 0.9 53.6 1.2 1.2 40.5 1.3 1.6 87.7 1.2 0.9 58.5 1.2 1.2 44.2 1.3 1.6 95.0 1.2 0.9 63.4 1.2 1.2 47.9 1.3 1.6 102.3 1.2 0.9 68.2 1.2 1.2 51.6 1.3 1.6 109.6 1.2 0.9 73.1 1.2 1.2 55.2 1.3 1.6 116.9 1.2 0.9 78.0 1.2 1.2 58.9 1.3 1.6 124.2 1.2 0.9 82.9 1.2 1.2 62.6 1.3 1.6 131.5 1.2 0.9 87.7 1.2 1.2 66.3 1.3 1.6 138.8 1.2 0.9 92.6 1.2 1.2 69.9 1.3 1.6 146.1 1.2 0.9 97.5 1.2 1.2 73.6 1.3 1.6 153.4 1.2 0.9 102.3 1.2 1.2 77.3 1.3 1.6 160.7 1.2 0.9 107.2 1.2 1.2 81.0 1.3 1.6 168.0 1.2 0.9 112.1 1.2 1.2 84.7 1.3 1.6 175.3 1.2 0.9 117.0 1.2 1.2 88.3 1.3 1.6 182.6 1.2 0.9 121.8 1.2 1.2 92.0 1.3 1.6 189.9 1.2 0.9 126.7 1.2 1.2 95.7 1.3 1.6 197.3 1.2 0.9 131.6 1.2 1.2 99.4 1.3 1.6 204.6 1.2 0.9 136.5 1.2 1.2 103.1 1.3 1.6 211.9 1.2 0.9 141.3 1.2 1.2 106.7 1.3 1.6 219.2 1.2 0.9 146.2 1.2 1.2 110.4 1.3 1.6

V1=3.5 T D V2
8.0 1.5 1.9 10.9 1.5 1.9 13.8 1.4 1.9 16.6 1.4 1.9 19.6 1.4 1.9 22.4 1.4 1.9 25.2 1.4 1.9 28.0 1.4 1.9 30.7 1.4 1.9 33.5 1.4 1.9 36.3 1.4 1.9 39.1 1.4 1.9 41.9 1.4 1.9 44.7 1.4 1.9 47.4 1.4 1.9 50.2 1.4 1.9 53.0 1.4 1.9 55.8 1.4 1.9 58.6 1.4 1.9 61.4 1.4 1.9 64.2 1.4 1.9 67.0 1.4 1.9 69.7 1.4 1.9 72.5 1.4 1.9 75.3 1.4 1.9 78.1 1.4 1.9 80.9 1.4 1.9 83.7 1.4 1.9

V1=4.0 T D V2
5.5 1.9 2.1 8.1 1.6 2.3 10.4 1.6 2.3 12.7 1.5 2.3 14.9 1.5 2.3 17.1 1.5 2.3 19.3 1.5 2.3 21.7 1.5 2.3 23.9 1.5 2.3 26.0 1.5 2.3 28.2 1.5 2.3 30.3 1.5 2.3 32.5 1.5 2.3 34.6 1.5 2.3 36.8 1.5 2.3 39.0 1.5 2.3 41.1 1.5 2.3 43.3 1.5 2.3 45.4 1.5 2.3 47.6 1.5 2.3 49.8 1.5 2.3 51.9 1.5 2.3 54.1 1.5 2.3 56.2 1.5 2.3 58.4 1.5 2.3 60.6 1.5 2.3 62.7 1.5 2.3 64.9 1.5 2.3

V1=4.5 T D V2
5.5 2.1 2.6 7.9 1.8 2.7 9.7 1.7 2.7 11.5 1.7 2.7 13.3 1.6 2.8 15.0 1.6 2.8 16.7 1.6 2.8 18.5 1.6 2.8 20.2 1.6 2.8 22.1 1.6 2.8 23.8 1.6 2.8 25.5 1.6 2.8 27.2 1.6 2.8 28.9 1.6 2.8 30.6 1.6 2.8 32.3 1.6 2.8 34.0 1.6 2.8 35.7 1.6 2.8 37.3 1.6 2.8 39.0 1.6 2.8 40.7 1.6 2.8 42.4 1.6 2.8 44.1 1.6 2.8 45.8 1.6 2.8 47.5 1.6 2.8 49.2 1.6 2.8 50.9 1.6 2.8

V1=5.0 T D V2
7.3 2.0 3.1 8.9 1.9 3.2 10.4 1.8 3.2 11.8 1.8 3.2 13.2 1.8 3.2 14.6 1.7 3.2 16.0 1.7 3.2 17.4 1.7 3.3 18.8 1.7 3.3 20.1 1.7 3.3 21.5 1.7 3.3 22.9 1.7 3.3 24.6 1.7 3.2 25.9 1.7 3.3 27.3 1.7 3.3 28.6 1.7 3.3 30.0 1.7 3.3 31.3 1.7 3.3 32.7 1.7 3.3 34.1 1.7 3.3 35.4 1.7 3.3 36.8 1.7 3.3 38.1 1.7 3.3 39.5 1.7 3.3 40.8 1.7 3.3

V1=5.5 T D V2
8.0 2.1 3.6 9.2 2.0 3.7 10.5 1.9 3.7 11.7 1.9 3.7 12.8 1.9 3.7 14.0 1.9 3.7 15.2 1.9 3.7 16.2 1.8 3.7 17.4 1.8 3.8 18.5 1.8 3.8 19.6 1.8 3.8 20.8 1.8 3.8 21.9 1.8 3.8 23.0 1.8 3.8 24.1 1.8 3.8 25.3 1.8 3.8 26.7 1.8 3.7 27.8 1.8 3.7 28.9 1.8 3.7 30.0 1.8 3.7 31.1 1.8 3.7 32.3 1.8 3.7 33.4 1.8 3.7

V1=6.0 T D V2
7.9 2.3 4.1 9.2 2.2 4.1 10.2 2.1 4.1 11.3 2.1 4.2 12.3 2.1 4.2 13.2 2.0 4.2 14.2 2.0 4.2 15.1 2.0 4.2 16.1 2.0 4.2 17.0 2.0 4.2 18.0 2.0 4.2 18.9 2.0 4.2 19.8 2.0 4.2 20.8 2.0 4.2 21.7 2.0 4.2 22.6 1.9 4.3 23.6 1.9 4.3 24.5 1.9 4.3 25.4 1.9 4.3 26.4 1.9 4.3 27.3 1.9 4.3

GaSWCC (Amended - 2000)

RETARDANCE "D" AND "B"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

GaSWCC (Amended - 2000)

Table 6-28.1. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "B" Grade 3.00 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

V1=3.0

V1=3.5

T D V2 T D V2 T D V2 T D V2 8.8 1.0 0.8 5.8 1.1 1.1 3.9 1.5 1.3 18.0 1.0 0.8 12.1 1.1 1.2 8.9 1.1 1.5 6.6 1.3 1.8 27.0 1.0 0.8 18.3 1.1 1.2 13.5 1.1 1.5 10.3 1.2 1.8 35.9 1.0 0.8 24.4 1.1 1.2 18.2 1.1 1.5 13.8 1.2 1.8 44.9 1.0 0.8 30.5 1.1 1.2 22.8 1.1 1.5 17.5 1.2 1.8 53.9 1.0 0.8 36.6 1.1 1.2 27.3 1.1 1.5 20.9 1.2 1.8 62.8 1.0 0.8 42.7 1.1 1.2 31.8 1.1 1.5 24.4 1.2 1.8 71.8 1.0 0.8 48.8 1.1 1.2 36.4 1.1 1.5 27.9 1.2 1.8 80.8 1.0 0.8 54.9 1.0 1.2 40.9 1.1 1.5 31.3 1.2 1.8 89.7 1.0 0.8 60.9 1.0 1.2 45.4 1.1 1.5 34.8 1.2 1.8 98.7 1.0 0.8 67.0 1.0 1.2 50.0 1.1 1.5 38.3 1.2 1.8 107.7 1.0 0.8 73.1 1.0 1.2 54.5 1.1 1.5 41.8 1.2 1.8 116.6 1.0 0.8 79.2 1.0 1.2 59.0 1.1 1.5 45.2 1.2 1.8 125.6 1.0 0.8 85.3 1.0 1.2 63.6 1.1 1.5 48.7 1.2 1.8 134.6 1.0 0.8 91.4 1.0 1.2 68.1 1.1 1.5 52.2 1.2 1.9 143.6 1.0 0.8 97.5 1.0 1.2 72.7 1.1 1.5 55.7 1.2 1.9 152.5 1.0 0.8 103.6 1.0 1.2 77.2 1.1 1.5 59.1 1.2 1.9 161.5 1.0 0.8 109.7 1.0 1.2 81.7 1.1 1.5 62.6 1.2 1.9 170.5 1.0 0.8 115.8 1.0 1.2 86.3 1.1 1.5 66.1 1.2 1.9 179.5 1.0 0.8 121.9 1.0 1.2 90.8 1.1 1.5 69.6 1.2 1.9 188.4 1.0 0.8 128.0 1.0 1.2 95.4 1.1 1.5 73.0 1.2 1.9 197.4 1.0 0.8 134.1 1.0 1.2 99.9 1.1 1.5 76.5 1.2 1.9 206.4 1.0 0.8 140.1 1.0 1.2 104.4 1.1 1.5 80.0 1.2 1.9 215.3 1.0 0.8 146.2 1.0 1.2 109.0 1.1 1.5 83.5 1.2 1.9 224.3 1.0 0.8 152.3 1.0 1.2 113.5 1.1 1.5 86.9 1.2 1.9 233.3 1.0 0.8 158.4 1.0 1.2 118.1 1.1 1.5 90.4 1.2 1.9 242.3 1.0 0.8 164.5 1.0 1.2 122.6 1.1 1.5 93.9 1.2 1.9 251.2 1.0 0.8 170.6 1.0 1.2 127.1 1.1 1.5 97.4 1.2 1.9 260.2 1.0 0.8 176.7 1.0 1.2 131.7 1.1 1.5 100.9 1.2 1.9 269.2 1.0 0.8 182.8 1.0 1.2 136.2 1.1 1.5 104.3 1.2 1.9

V1=4.0
T D V2
4.7 1.5 2.1 7.9 1.3 2.2 10.7 1.3 2.2 13.4 1.3 2.2 16.2 1.3 2.2 19.1 1.2 2.2 21.9 1.2 2.2 24.6 1.2 2.2 27.3 1.2 2.2 30.0 1.2 2.2 32.7 1.2 2.2 35.5 1.2 2.2 38.2 1.2 2.2 40.9 1.2 2.2 43.6 1.2 2.2 46.3 1.2 2.2 49.1 1.2 2.2 51.8 1.2 2.2 54.5 1.2 2.2 57.2 1.2 2.2 60.0 1.2 2.2 62.7 1.2 2.2 65.4 1.2 2.2 68.1 1.2 2.2 70.9 1.2 2.2 73.6 1.2 2.2 76.3 1.2 2.2 79.0 1.2 2.2 81.7 1.2 2.2

V1=4.5 T D V2
6.0 1.5 2.5 8.3 1.4 2.6 10.6 1.4 2.6 12.8 1.4 2.6 15.0 1.3 2.6 17.2 1.3 2.6 19.6 1.3 2.6 21.8 1.3 2.6 24.0 1.3 2.6 26.1 1.3 2.6 28.3 1.3 2.6 30.5 1.3 2.6 32.6 1.3 2.6 34.8 1.3 2.6 37.0 1.3 2.6 39.1 1.3 2.6 41.3 1.3 2.6 43.5 1.3 2.6 45.6 1.3 2.6 47.8 1.3 2.6 50.0 1.3 2.6 52.2 1.3 2.6 54.3 1.3 2.6 56.5 1.3 2.6 58.7 1.3 2.6 60.8 1.3 2.6 63.0 1.3 2.6 65.2 1.3 2.6

V1=5.0 T D V2
6.4 1.6 3.0 8.3 1.5 3.0 10.2 1.5 3.0 12.0 1.4 3.0 13.8 1.4 3.1 15.5 1.4 3.1 17.3 1.4 3.1 19.1 1.4 3.1 21.0 1.4 3.1 22.8 1.4 3.1 24.5 1.4 3.1 26.2 1.4 3.1 28.0 1.4 3.1 29.7 1.4 3.1 31.5 1.4 3.1 33.2 1.4 3.1 35.0 1.4 3.1 36.7 1.4 3.1 38.4 1.4 3.1 40.2 1.4 3.1 41.9 1.4 3.1 43.7 1.4 3.1 45.4 1.4 3.1 47.2 1.4 3.1 48.9 1.4 3.1 50.7 1.4 3.1 52.4 1.4 3.1

V1=5.5 T D V2
6.4 1.7 3.4 8.1 1.6 3.5 9.6 1.6 3.5 11.1 1.5 3.5 12.6 1.5 3.5 14.1 1.5 3.5 15.5 1.5 3.5 16.9 1.5 3.6 18.4 1.5 3.6 19.8 1.5 3.6 21.5 1.5 3.5 23.0 1.5 3.5 24.4 1.5 3.6 25.8 1.5 3.6 27.2 1.5 3.6 28.7 1.5 3.6 30.1 1.5 3.6 31.5 1.5 3.6 32.9 1.5 3.6 34.4 1.5 3.6 35.8 1.5 3.6 37.2 1.5 3.6 38.6 1.5 3.6 40.1 1.5 3.6 41.5 1.5 3.6 42.9 1.5 3.6

V1=6.0 T D V2
6.0 1.9 3.9 7.6 1.7 3.9 9.0 1.7 4.0 10.2 1.7 4.0 11.5 1.6 4.0 12.7 1.6 4.0 14.0 1.6 4.0 15.1 1.6 4.0 16.3 1.6 4.1 17.5 1.6 4.1 18.8 1.6 4.1 20.0 1.6 4.1 21.2 1.6 4.1 22.6 1.6 4.0 23.8 1.6 4.0 25.0 1.6 4.0 26.2 1.6 4.0 27.4 1.6 4.0 28.6 1.6 4.0 29.8 1.6 4.0 30.9 1.6 4.0 32.1 1.6 4.1 33.3 1.6 4.1 34.5 1.6 4.1 35.7 1.6 4.1

6-213

RETARDANCE "D" AND "B"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

6-214

Table 6-28.1. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "B" Grade 4.00 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

V1=3.0

V1=3.5

T D V2 T D V2 T D V2 T D V2 10.1 0.9 0.8 7.0 1.0 1.1 4.9 1.1 1.4 20.5 0.9 0.8 14.4 0.9 1.1 10.3 1.0 1.4 7.9 1.1 1.8 30.7 0.9 0.8 21.5 0.9 1.1 15.7 1.0 1.4 12.0 1.1 1.8 40.9 0.9 0.8 28.6 0.9 1.1 20.9 1.0 1.4 16.3 1.0 1.8 51.1 0.9 0.8 35.8 0.9 1.1 26.1 1.0 1.4 20.3 1.0 1.8 61.3 0.9 0.8 42.9 0.9 1.1 31.4 1.0 1.4 24.4 1.0 1.8 71.5 0.9 0.8 50.1 0.9 1.1 36.6 1.0 1.4 28.3 1.0 1.8 81.8 0.9 0.8 57.2 0.9 1.1 41.8 1.0 1.5 32.4 1.0 1.8 92.0 0.9 0.8 64.4 0.9 1.1 47.0 1.0 1.5 36.4 1.0 1.8 102.2 0.9 0.8 71.5 0.9 1.1 52.2 1.0 1.5 40.5 1.0 1.8 112.4 0.9 0.8 78.7 0.9 1.1 57.5 1.0 1.5 44.5 1.0 1.8 122.6 0.9 0.8 85.8 0.9 1.1 62.7 1.0 1.5 48.5 1.0 1.8 132.8 0.9 0.8 93.0 0.9 1.1 67.9 1.0 1.5 52.6 1.0 1.8 143.1 0.9 0.8 100.1 0.9 1.1 73.1 1.0 1.5 56.6 1.0 1.8 153.3 0.9 0.8 107.3 0.9 1.1 78.3 1.0 1.5 60.7 1.0 1.8 163.5 0.9 0.8 114.4 0.9 1.1 83.6 1.0 1.5 64.7 1.0 1.8 173.7 0.9 0.8 121.6 0.9 1.1 88.8 1.0 1.5 68.8 1.0 1.8 183.9 0.9 0.8 128.7 0.9 1.1 94.0 1.0 1.5 72.8 1.0 1.8 194.1 0.9 0.8 135.9 0.9 1.1 99.2 1.0 1.5 76.8 1.0 1.8 204.4 0.9 0.8 143.0 0.9 1.1 104.4 1.0 1.5 80.9 1.0 1.8 214.6 0.9 0.8 150.2 0.9 1.1 109.7 1.0 1.5 84.9 1.0 1.8 224.8 0.9 0.8 157.4 0.9 1.1 114.9 1.0 1.5 89.0 1.0 1.8 235.0 0.9 0.8 164.5 0.9 1.1 120.1 1.0 1.5 93.0 1.0 1.8 245.2 0.9 0.8 171.7 0.9 1.1 125.3 1.0 1.5 97.1 1.0 1.8 255.5 0.9 0.8 178.8 0.9 1.1 130.5 1.0 1.5 101.1 1.0 1.8 265.7 0.9 0.8 186.0 0.9 1.1 135.8 1.0 1.5 105.1 1.0 1.8 275.9 0.9 0.8 193.1 0.9 1.1 141.0 1.0 1.5 109.2 1.0 1.8 286.1 0.9 0.8 200.3 0.9 1.1 146.2 1.0 1.5 113.2 1.0 1.8 296.3 0.9 0.8 207.4 0.9 1.1 151.4 1.0 1.5 117.3 1.0 1.8 306.5 0.9 0.8 214.6 0.9 1.1 156.7 1.0 1.5 121.3 1.0 1.8

V1=4.0
T D V2
6.1 1.2 2.1 9.4 1.1 2.1 12.6 1.1 2.1 16.0 1.1 2.1 19.2 1.1 2.1 22.4 1.1 2.1 25.6 1.1 2.1 28.8 1.1 2.1 32.0 1.1 2.1 35.2 1.1 2.1 38.4 1.1 2.2 41.5 1.1 2.2 44.7 1.1 2.2 47.9 1.1 2.2 51.1 1.1 2.2 54.3 1.1 2.2 57.5 1.1 2.2 60.7 1.1 2.2 63.9 1.1 2.2 67.1 1.1 2.2 70.3 1.1 2.2 73.5 1.1 2.2 76.7 1.1 2.2 79.9 1.1 2.2 83.0 1.1 2.2 86.2 1.1 2.2 89.4 1.1 2.2 92.6 1.1 2.2 95.8 1.1 2.2

V1=4.5
T D V2
4.5 1.4 2.4 7.4 1.2 2.5 10.1 1.2 2.5 12.7 1.2 2.5 15.2 1.2 2.5 18.0 1.2 2.5 20.6 1.2 2.5 23.1 1.2 2.5 25.7 1.2 2.5 28.2 1.2 2.5 30.8 1.2 2.5 33.4 1.2 2.5 35.9 1.2 2.5 38.5 1.2 2.5 41.0 1.2 2.5 43.6 1.2 2.5 46.2 1.2 2.5 48.7 1.2 2.5 51.3 1.2 2.5 53.9 1.2 2.5 56.4 1.2 2.5 59.0 1.2 2.5 61.5 1.2 2.5 64.1 1.2 2.5 66.7 1.2 2.5 69.2 1.2 2.5 71.8 1.2 2.5 74.4 1.2 2.5 76.9 1.2 2.5

V1=5.0 T D V2
5.8 1.4 2.8 8.0 1.3 2.9 10.2 1.3 2.9 12.3 1.3 2.9 14.4 1.2 2.9 16.5 1.2 2.9 18.8 1.2 2.9 20.9 1.2 2.9 23.0 1.2 2.9 25.1 1.2 2.9 27.2 1.2 2.9 29.2 1.2 2.9 31.3 1.2 2.9 33.4 1.2 2.9 35.5 1.2 2.9 37.6 1.2 2.9 39.7 1.2 2.9 41.7 1.2 2.9 43.8 1.2 2.9 45.9 1.2 2.9 48.0 1.2 2.9 49.9 1.2 3.0 52.0 1.2 3.0 54.1 1.2 3.0 56.1 1.2 3.0 58.2 1.2 3.0 60.3 1.2 3.0 62.4 1.2 3.0

V1=5.5 T D V2
6.3 1.4 3.3 8.2 1.4 3.4 10.0 1.3 3.4 11.7 1.3 3.4 13.5 1.3 3.4 15.2 1.3 3.4 17.0 1.3 3.4 18.9 1.3 3.4 20.6 1.3 3.4 22.3 1.3 3.4 24.0 1.3 3.4 25.7 1.3 3.4 27.4 1.3 3.4 29.1 1.3 3.4 30.8 1.3 3.4 32.5 1.3 3.4 34.2 1.3 3.4 35.9 1.3 3.4 37.6 1.3 3.4 39.3 1.3 3.4 41.0 1.3 3.4 42.7 1.3 3.4 44.4 1.3 3.4 46.1 1.3 3.4 47.8 1.3 3.4 49.6 1.3 3.4 51.3 1.3 3.4

V1=6.0 T D V2
6.5 1.5 3.8 8.1 1.5 3.8 9.6 1.4 3.8 11.1 1.4 3.8 12.6 1.4 3.9 14.0 1.4 3.9 15.4 1.4 3.9 16.9 1.4 3.9 18.3 1.4 3.9 20.0 1.4 3.9 21.4 1.4 3.9 22.8 1.4 3.9 24.2 1.4 3.9 25.7 1.4 3.9 27.1 1.4 3.9 28.5 1.3 3.9 29.9 1.3 3.9 31.3 1.3 3.9 32.7 1.3 3.9 34.2 1.3 3.9 35.6 1.3 3.9 37.0 1.3 3.9 38.4 1.3 3.9 39.9 1.3 3.9 41.3 1.3 3.9 42.7 1.3 3.9

GaSWCC (Amended - 2000)

RETARDANCE "D" AND "B"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

GaSWCC (Amended - 2000)

Table 6-28.1. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "B" Grade 5.00 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

V1=3.0

V1=3.5

V1=4.0

T D V2 T D V2 T D V2 T D V2 T D V2 11.3 0.8 0.8 8.0 0.9 1.1 5.6 1.0 1.4 4.2 1.1 1.6 22.5 0.8 0.8 16.3 0.9 1.1 11.5 0.9 1.4 8.9 1.0 1.7 7.0 1.0 2.0 33.7 0.8 0.8 24.3 0.9 1.1 17.4 0.9 1.4 13.7 1.0 1.7 10.7 1.0 2.1 45.0 0.8 0.8 32.4 0.9 1.1 23.2 0.9 1.4 18.2 1.0 1.7 14.5 1.0 2.1 56.2 0.8 0.8 40.5 0.9 1.1 28.9 0.9 1.4 22.8 1.0 1.7 18.1 1.0 2.1 67.4 0.8 0.8 48.7 0.9 1.1 34.7 0.9 1.4 27.3 1.0 1.7 21.7 1.0 2.1 78.7 0.8 0.8 56.8 0.9 1.1 40.5 0.9 1.4 31.8 1.0 1.7 25.3 1.0 2.1 89.9 0.8 0.8 64.9 0.9 1.1 46.3 0.9 1.4 36.4 1.0 1.7 28.8 1.0 2.1 101.1 0.8 0.8 73.0 0.9 1.1 52.1 0.9 1.4 40.9 1.0 1.7 32.4 1.0 2.1 112.4 0.8 0.8 81.1 0.9 1.1 57.9 0.9 1.4 45.5 1.0 1.7 36.0 1.0 2.1 123.6 0.8 0.8 89.2 0.9 1.1 63.6 0.9 1.4 50.0 1.0 1.7 39.6 1.0 2.1 134.8 0.8 0.8 97.3 0.9 1.1 69.4 0.9 1.4 54.5 1.0 1.7 43.2 1.0 2.1 146.1 0.8 0.8 105.4 0.9 1.1 75.2 0.9 1.4 59.1 1.0 1.7 46.8 1.0 2.1 157.3 0.8 0.8 113.5 0.9 1.1 81.0 0.9 1.4 63.6 1.0 1.7 50.4 1.0 2.1 168.6 0.8 0.8 121.6 0.9 1.1 86.8 0.9 1.4 68.2 1.0 1.7 54.0 1.0 2.1 179.8 0.8 0.8 129.7 0.9 1.1 92.6 0.9 1.4 72.7 0.9 1.7 57.6 1.0 2.1 191.0 0.8 0.8 137.8 0.9 1.1 98.3 0.9 1.4 77.3 0.9 1.7 61.2 1.0 2.1 202.3 0.8 0.8 145.9 0.9 1.1 104.1 0.9 1.4 81.8 0.9 1.7 64.9 1.0 2.1 213.5 0.8 0.8 154.0 0.9 1.1 109.9 0.9 1.4 86.3 0.9 1.7 68.5 1.0 2.1 224.7 0.8 0.8 162.1 0.9 1.1 115.7 0.9 1.4 90.9 0.9 1.7 72.1 1.0 2.1 236.0 0.8 0.8 170.2 0.9 1.1 121.5 0.9 1.4 95.4 0.9 1.7 75.7 1.0 2.1 247.2 0.8 0.8 178.3 0.9 1.1 127.3 0.9 1.4 100.0 0.9 1.7 79.3 1.0 2.1 258.5 0.8 0.8 186.4 0.9 1.1 133.0 0.9 1.4 104.5 0.9 1.7 82.9 1.0 2.1 269.7 0.8 0.8 194.6 0.9 1.1 138.8 0.9 1.4 109.1 0.9 1.7 86.5 1.0 2.1 280.9 0.8 0.8 202.7 0.9 1.1 144.6 0.9 1.4 113.6 0.9 1.7 90.1 1.0 2.1 292.2 0.8 0.8 210.8 0.9 1.1 150.4 0.9 1.4 118.2 0.9 1.7 93.7 1.0 2.1 303.4 0.8 0.8 218.9 0.9 1.1 156.2 0.9 1.4 122.7 0.9 1.7 97.3 1.0 2.1 314.6 0.8 0.8 227.0 0.9 1.1 162.0 0.9 1.4 127.2 0.9 1.7 100.9 1.0 2.1 325.9 0.8 0.8 235.1 0.9 1.1 167.8 0.9 1.4 131.8 0.9 1.7 104.5 1.0 2.1 337.1 0.8 0.8 243.2 0.9 1.1 173.5 0.9 1.4 136.3 0.9 1.7 108.1 1.0 2.1

V1=4.5
T D V2
5.5 1.2 2.4 8.5 1.1 2.4 11.5 1.1 2.5 14.6 1.1 2.4 17.5 1.1 2.4 20.4 1.0 2.5 23.3 1.0 2.5 26.2 1.0 2.5 29.1 1.0 2.5 32.0 1.0 2.5 34.9 1.0 2.5 37.8 1.0 2.5 40.7 1.0 2.5 43.6 1.0 2.5 46.5 1.0 2.5 49.4 1.0 2.5 52.3 1.0 2.5 55.2 1.0 2.5 58.1 1.0 2.5 61.0 1.0 2.5 64.0 1.0 2.5 66.9 1.0 2.5 69.8 1.0 2.5 72.7 1.0 2.5 75.6 1.0 2.5 78.5 1.0 2.5 81.4 1.0 2.5 84.3 1.0 2.5 87.2 1.0 2.5

V1=5.0
T D V2
4.0 1.4 2.6 6.8 1.2 2.8 9.3 1.1 2.8 11.7 1.1 2.8 14.1 1.1 2.8 16.7 1.1 2.8 19.1 1.1 2.8 21.5 1.1 2.8 23.9 1.1 2.8 26.2 1.1 2.8 28.6 1.1 2.8 31.0 1.1 2.8 33.4 1.1 2.8 35.8 1.1 2.8 38.1 1.1 2.8 40.5 1.1 2.8 42.9 1.1 2.8 45.3 1.1 2.8 47.7 1.1 2.8 50.0 1.1 2.8 52.4 1.1 2.8 54.8 1.1 2.8 57.2 1.1 2.8 59.6 1.1 2.8 61.9 1.1 2.8 64.3 1.1 2.8 66.7 1.1 2.8 69.1 1.1 2.8 71.5 1.1 2.8

V1=5.5 T D V2
5.4 1.3 3.2 7.5 1.2 3.2 9.6 1.2 3.3 11.6 1.2 3.3 13.6 1.2 3.3 15.6 1.2 3.3 17.7 1.2 3.3 19.7 1.2 3.3 21.7 1.2 3.3 23.6 1.2 3.3 25.6 1.2 3.3 27.5 1.2 3.3 29.4 1.2 3.3 31.4 1.2 3.3 33.3 1.2 3.3 35.3 1.2 3.3 37.2 1.2 3.3 39.2 1.2 3.3 41.1 1.2 3.3 43.1 1.2 3.3 45.0 1.2 3.3 47.0 1.2 3.3 48.9 1.2 3.3 50.9 1.2 3.3 52.9 1.2 3.3 54.8 1.2 3.3 56.8 1.2 3.3 58.7 1.2 3.3

V1=6.0 T D V2
6.1 1.4 3.7 7.8 1.3 3.7 9.5 1.3 3.7 11.2 1.3 3.7 12.9 1.2 3.7 14.6 1.2 3.7 16.2 1.2 3.7 18.0 1.2 3.8 19.7 1.2 3.8 21.3 1.2 3.8 22.9 1.2 3.8 24.5 1.2 3.8 26.2 1.2 3.8 27.8 1.2 3.8 29.4 1.2 3.8 31.1 1.2 3.8 32.7 1.2 3.8 34.3 1.2 3.8 36.0 1.2 3.8 37.6 1.2 3.8 39.2 1.2 3.8 40.9 1.2 3.8 42.5 1.2 3.8 44.1 1.2 3.8 45.8 1.2 3.8 47.4 1.2 3.8 49.0 1.2 3.8

6-215

RETARDANCE "D" AND "B"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

6-216

Table 6-28.1. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "B" Grade 6.00 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

V1=3.0

V1=3.5

V1=4.0

T D V2 T D V2 T D V2 T D V2 T D V2 12.4 0.7 0.8 8.7 0.8 1.0 6.2 0.9 1.4 4.7 1.0 1.6 3.5 1.2 1.9 24.7 0.7 0.8 17.6 0.8 1.0 12.8 0.9 1.4 9.8 0.9 1.7 7.8 1.0 2.0 37.1 0.7 0.8 26.4 0.8 1.1 19.2 0.8 1.4 15.0 0.9 1.7 11.8 0.9 2.0 49.4 0.7 0.8 35.1 0.8 1.1 25.6 0.8 1.4 19.9 0.9 1.7 16.0 0.9 2.0 61.8 0.7 0.8 43.9 0.8 1.1 32.0 0.8 1.4 24.9 0.9 1.7 19.9 0.9 2.0 74.1 0.7 0.8 52.7 0.8 1.1 38.4 0.8 1.4 29.9 0.9 1.7 23.8 0.9 2.1 86.5 0.7 0.8 61.5 0.8 1.1 44.8 0.8 1.4 34.8 0.9 1.7 27.8 0.9 2.1 98.9 0.7 0.8 70.2 0.8 1.1 51.2 0.8 1.4 39.8 0.9 1.7 31.8 0.9 2.1 111.2 0.7 0.8 79.0 0.8 1.1 57.6 0.8 1.4 44.8 0.9 1.7 35.7 0.9 2.1 123.6 0.7 0.8 87.8 0.8 1.1 64.0 0.8 1.4 49.7 0.9 1.7 39.7 0.9 2.1 135.9 0.7 0.8 96.6 0.8 1.1 70.4 0.8 1.4 54.7 0.9 1.7 43.6 0.9 2.1 148.3 0.7 0.8 105.3 0.8 1.1 76.8 0.8 1.4 59.7 0.9 1.7 47.6 0.9 2.1 160.6 0.7 0.8 114.1 0.8 1.1 83.2 0.8 1.4 64.7 0.9 1.7 51.6 0.9 2.1 173.0 0.7 0.8 122.9 0.8 1.1 89.6 0.8 1.4 69.6 0.9 1.7 55.5 0.9 2.1 185.4 0.7 0.8 131.7 0.8 1.1 96.0 0.8 1.4 74.6 0.9 1.7 59.5 0.9 2.1 197.7 0.7 0.8 140.4 0.8 1.1 102.3 0.8 1.4 79.6 0.9 1.7 63.5 0.9 2.1 210.1 0.7 0.8 149.2 0.8 1.1 108.7 0.8 1.4 84.5 0.9 1.7 67.4 0.9 2.1 222.4 0.7 0.8 158.0 0.8 1.1 115.1 0.8 1.4 89.5 0.9 1.7 71.4 0.9 2.1 234.8 0.7 0.8 166.8 0.8 1.1 121.5 0.8 1.4 94.5 0.9 1.7 75.4 0.9 2.1 247.1 0.7 0.8 175.5 0.8 1.1 127.9 0.8 1.4 99.5 0.9 1.7 79.3 0.9 2.1 259.5 0.7 0.8 184.3 0.8 1.1 134.3 0.8 1.4 104.4 0.9 1.7 83.3 0.9 2.1 271.8 0.7 0.8 193.1 0.8 1.1 140.7 0.8 1.4 109.4 0.9 1.7 87.3 0.9 2.1 284.2 0.7 0.8 201.9 0.8 1.1 147.1 0.8 1.4 114.4 0.9 1.7 91.2 0.9 2.1 296.6 0.7 0.8 210.7 0.8 1.1 153.5 0.8 1.4 119.3 0.9 1.7 95.2 0.9 2.1 308.9 0.7 0.8 219.4 0.8 1.1 159.9 0.8 1.4 124.3 0.9 1.7 99.2 0.9 2.1 321.3 0.7 0.8 228.2 0.8 1.1 166.3 0.8 1.4 129.3 0.9 1.7 103.1 0.9 2.1 333.6 0.7 0.8 237.0 0.8 1.1 172.7 0.8 1.4 134.3 0.9 1.7 107.1 0.9 2.1 346.0 0.7 0.8 245.8 0.8 1.1 179.1 0.8 1.4 139.2 0.9 1.7 111.0 0.9 2.1 358.3 0.7 0.8 254.5 0.8 1.1 185.5 0.8 1.4 144.2 0.9 1.7 115.0 0.9 2.1 370.7 0.7 0.8 263.3 0.8 1.1 191.9 0.8 1.4 149.2 0.9 1.7 119.0 0.9 2.1

V1=4.5
T D V2
6.2 1.0 2.3 9.5 1.0 2.4 12.9 1.0 2.4 16.1 1.0 2.4 19.3 1.0 2.4 22.5 1.0 2.4 25.7 1.0 2.4 29.0 1.0 2.4 32.2 1.0 2.4 35.4 1.0 2.4 38.6 1.0 2.4 41.8 1.0 2.4 45.0 1.0 2.4 48.2 1.0 2.4 51.4 1.0 2.4 54.7 1.0 2.4 57.9 1.0 2.4 61.1 1.0 2.4 64.3 1.0 2.4 67.5 1.0 2.4 70.7 1.0 2.4 73.9 1.0 2.4 77.2 1.0 2.4 80.4 1.0 2.4 83.6 1.0 2.4 86.8 1.0 2.4 90.0 1.0 2.4 93.2 1.0 2.4 96.4 1.0 2.4

V1=5.0
T D V2
4.9 1.1 2.7 7.7 1.1 2.7 10.4 1.0 2.8 13.1 1.0 2.8 15.9 1.0 2.8 18.5 1.0 2.8 21.2 1.0 2.8 23.8 1.0 2.8 26.4 1.0 2.8 29.1 1.0 2.8 31.7 1.0 2.8 34.3 1.0 2.8 37.0 1.0 2.8 39.6 1.0 2.8 42.2 1.0 2.8 44.9 1.0 2.8 47.5 1.0 2.8 50.2 1.0 2.8 52.8 1.0 2.8 55.4 1.0 2.8 58.1 1.0 2.8 60.7 1.0 2.8 63.3 1.0 2.8 66.0 1.0 2.8 68.6 1.0 2.8 71.3 1.0 2.8 73.9 1.0 2.8 76.5 1.0 2.8 79.2 1.0 2.8

V1=5.5 T D V2
6.2 1.2 3.1 8.5 1.1 3.2 10.8 1.1 3.2 13.0 1.1 3.2 15.4 1.1 3.2 17.6 1.1 3.2 19.8 1.1 3.2 22.0 1.1 3.2 24.2 1.1 3.2 26.3 1.1 3.2 28.5 1.1 3.2 30.7 1.1 3.2 32.9 1.1 3.2 35.1 1.1 3.2 37.3 1.1 3.2 39.5 1.1 3.2 41.7 1.1 3.2 43.9 1.1 3.2 46.1 1.1 3.2 48.2 1.1 3.2 50.4 1.1 3.2 52.6 1.1 3.2 54.8 1.1 3.2 57.0 1.1 3.2 59.2 1.1 3.2 61.4 1.1 3.2 63.6 1.1 3.2 65.8 1.1 3.2

V1=6.0 T D V2
5.0 1.3 3.5 7.0 1.2 3.6 8.9 1.2 3.6 10.8 1.1 3.6 12.7 1.1 3.6 14.5 1.1 3.6 16.6 1.1 3.6 18.4 1.1 3.6 20.2 1.1 3.7 22.0 1.1 3.7 23.8 1.1 3.7 25.6 1.1 3.7 27.4 1.1 3.7 29.3 1.1 3.7 31.1 1.1 3.7 32.9 1.1 3.7 34.7 1.1 3.7 36.6 1.1 3.7 38.4 1.1 3.7 40.2 1.1 3.7 42.0 1.1 3.7 43.9 1.1 3.7 45.7 1.1 3.7 47.5 1.1 3.7 49.3 1.1 3.7 51.2 1.1 3.7 53.0 1.1 3.7 54.8 1.1 3.7

GaSWCC (Amended - 2000)

RETARDANCE "D" AND "B"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

GaSWCC (Amended - 2000)

Table 6-28.1. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "B" Grade 8.00 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

V1=3.0

V1=3.5

V1=4.0

V1=4.5

T D V2 T D V2 T D V2 T D V2 T D V2 T D V2 14.0 0.7 0.8 10.1 0.7 1.0 7.4 0.8 1.3 5.5 0.8 1.6 4.4 0.9 1.9 3.4 1.0 2.1 28.0 0.7 0.8 20.1 0.7 1.0 15.0 0.8 1.3 11.3 0.8 1.7 9.1 0.8 2.0 7.4 0.9 2.3 41.9 0.7 0.8 30.1 0.7 1.0 22.4 0.8 1.3 17.0 0.8 1.7 13.9 0.8 2.0 11.4 0.9 2.3 55.9 0.7 0.8 40.1 0.7 1.0 29.9 0.8 1.3 22.6 0.8 1.7 18.5 0.8 2.0 15.1 0.9 2.3 69.9 0.7 0.8 50.1 0.7 1.0 37.3 0.8 1.3 28.2 0.8 1.7 23.1 0.8 2.0 18.8 0.9 2.3 83.9 0.7 0.8 60.1 0.7 1.0 44.8 0.8 1.3 33.9 0.8 1.7 27.7 0.8 2.0 22.6 0.9 2.3 97.9 0.7 0.8 70.1 0.7 1.0 52.3 0.8 1.3 39.5 0.8 1.7 32.3 0.8 2.0 26.3 0.9 2.3 111.8 0.7 0.8 80.2 0.7 1.0 59.7 0.8 1.3 45.1 0.8 1.7 36.9 0.8 2.0 30.1 0.9 2.3 125.8 0.7 0.8 90.2 0.7 1.0 67.2 0.8 1.3 50.8 0.8 1.7 41.5 0.8 2.0 33.8 0.9 2.3 139.8 0.7 0.8 100.2 0.7 1.0 74.7 0.8 1.3 56.4 0.8 1.7 46.1 0.8 2.0 37.6 0.9 2.3 153.8 0.7 0.8 110.2 0.7 1.0 82.1 0.8 1.3 62.1 0.8 1.7 50.7 0.8 2.0 41.3 0.9 2.3 167.8 0.7 0.8 120.2 0.7 1.0 89.6 0.8 1.3 67.7 0.8 1.7 55.3 0.8 2.0 45.1 0.9 2.3 181.7 0.7 0.8 130.3 0.7 1.0 97.0 0.8 1.3 73.3 0.8 1.7 60.0 0.8 2.0 48.8 0.9 2.3 195.7 0.7 0.8 140.3 0.7 1.0 104.5 0.8 1.3 79.0 0.8 1.7 64.6 0.8 2.0 52.6 0.9 2.3 209.7 0.7 0.8 150.3 0.7 1.0 112.0 0.8 1.3 84.6 0.8 1.7 69.2 0.8 2.0 56.3 0.9 2.3 223.7 0.7 0.8 160.3 0.7 1.0 119.4 0.8 1.3 90.3 0.8 1.7 73.8 0.8 2.0 60.1 0.9 2.3 237.7 0.7 0.8 170.3 0.7 1.0 126.9 0.8 1.3 95.9 0.8 1.7 78.4 0.8 2.0 63.8 0.9 2.3 251.6 0.7 0.8 180.3 0.7 1.0 134.4 0.8 1.3 101.6 0.8 1.7 83.0 0.8 2.0 67.6 0.9 2.3 265.6 0.7 0.8 190.4 0.7 1.0 141.8 0.8 1.3 107.2 0.8 1.7 87.6 0.8 2.0 71.3 0.9 2.3 279.6 0.7 0.8 200.4 0.7 1.0 149.3 0.8 1.3 112.8 0.8 1.7 92.2 0.8 2.0 75.1 0.9 2.3 293.6 0.7 0.8 210.4 0.7 1.0 156.8 0.8 1.3 118.5 0.8 1.7 96.8 0.8 2.0 78.9 0.9 2.3 307.6 0.7 0.8 220.4 0.7 1.0 164.2 0.8 1.3 124.1 0.8 1.7 101.4 0.8 2.0 82.6 0.9 2.3 321.5 0.7 0.8 230.4 0.7 1.0 171.7 0.8 1.3 129.8 0.8 1.7 106.1 0.8 2.0 86.4 0.9 2.3 335.5 0.7 0.8 240.5 0.7 1.0 179.1 0.8 1.3 135.4 0.8 1.7 110.7 0.8 2.0 90.1 0.9 2.3 349.5 0.7 0.8 250.5 0.7 1.0 186.6 0.8 1.3 141.0 0.8 1.7 115.3 0.8 2.0 93.9 0.9 2.3 363.5 0.7 0.8 260.5 0.7 1.0 194.1 0.8 1.3 146.7 0.8 1.7 119.9 0.8 2.0 97.6 0.9 2.3 377.5 0.7 0.8 270.5 0.7 1.0 201.5 0.8 1.3 152.3 0.8 1.7 124.5 0.8 2.0 101.4 0.9 2.3 391.5 0.7 0.8 280.5 0.7 1.0 209.0 0.8 1.3 158.0 0.8 1.7 129.1 0.8 2.0 105.1 0.9 2.3 405.4 0.7 0.8 290.6 0.7 1.0 216.5 0.8 1.3 163.6 0.8 1.7 133.7 0.8 2.0 108.9 0.9 2.3 419.4 0.7 0.8 300.6 0.7 1.0 223.9 0.8 1.3 169.3 0.8 1.7 138.3 0.8 2.0 112.6 0.9 2.3

V1=5.0
T D V2
6.0 0.9 2.6 9.2 0.9 2.7 12.5 0.9 2.7 15.6 0.9 2.7 18.6 0.9 2.7 21.7 0.9 2.7 24.8 0.9 2.7 27.9 0.9 2.7 31.0 0.9 2.7 34.1 0.9 2.7 37.2 0.9 2.7 40.3 0.9 2.7 43.4 0.9 2.7 46.5 0.9 2.7 49.6 0.9 2.7 52.7 0.9 2.7 55.8 0.9 2.7 58.9 0.9 2.7 62.0 0.9 2.7 65.1 0.9 2.7 68.2 0.9 2.7 71.3 0.9 2.7 74.4 0.9 2.7 77.5 0.9 2.7 80.6 0.9 2.7 83.7 0.9 2.7 86.8 0.9 2.7 89.9 0.9 2.7 93.0 0.9 2.7

V1=5.5
T D V2
4.9 1.0 3.0 7.6 1.0 3.0 10.2 1.0 3.1 13.0 0.9 3.1 15.6 0.9 3.1 18.2 0.9 3.1 20.8 0.9 3.1 23.3 0.9 3.1 25.9 0.9 3.1 28.5 0.9 3.1 31.1 0.9 3.1 33.7 0.9 3.1 36.3 0.9 3.1 38.9 0.9 3.1 41.4 0.9 3.1 44.0 0.9 3.1 46.6 0.9 3.1 49.2 0.9 3.1 51.8 0.9 3.1 54.4 0.9 3.1 57.0 0.9 3.1 59.6 0.9 3.1 62.2 0.9 3.1 64.7 0.9 3.1 67.3 0.9 3.1 69.9 0.9 3.1 72.5 0.9 3.1 75.1 0.9 3.1 77.7 0.9 3.1

V1=6.0
T D V2
3.8 1.2 3.3 6.3 1.0 3.4 8.5 1.0 3.5 10.8 1.0 3.5 13.0 1.0 3.5 15.3 1.0 3.5 17.5 1.0 3.5 19.7 1.0 3.5 21.9 1.0 3.5 24.0 1.0 3.5 26.2 1.0 3.5 28.4 1.0 3.5 30.6 1.0 3.5 32.8 1.0 3.5 35.0 1.0 3.5 37.1 1.0 3.5 39.3 1.0 3.5 41.5 1.0 3.5 43.7 1.0 3.5 45.9 1.0 3.5 48.0 1.0 3.5 50.2 1.0 3.5 52.4 1.0 3.5 54.6 1.0 3.5 56.8 1.0 3.5 59.0 1.0 3.5 61.1 1.0 3.5 63.3 1.0 3.5 65.5 1.0 3.5

6-217

RETARDANCE "D" AND "B"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

6-218

Table 6-28.1. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "B" Grade 10.00 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

V1=3.0

V1=3.5

V1=4.0

V1=4.5

V1=5.0

T D V2 T D V2 T D V2 T D V2 T D V2 T D V2 T D V2 15.3 0.6 0.8 11.1 0.7 1.0 8.1 0.7 1.3 6.3 0.7 1.6 4.8 0.8 1.9 4.0 0.9 2.2 3.1 1.0 2.4 30.6 0.6 0.8 22.1 0.7 1.0 16.5 0.7 1.3 12.8 0.7 1.6 10.0 0.8 2.0 8.4 0.8 2.2 6.9 0.8 2.6 45.9 0.6 0.8 33.2 0.7 1.0 24.7 0.7 1.3 19.2 0.7 1.6 15.0 0.8 2.0 12.7 0.8 2.2 10.5 0.8 2.6 61.2 0.6 0.8 44.2 0.7 1.0 32.9 0.7 1.3 25.6 0.7 1.6 20.0 0.8 2.0 17.0 0.8 2.2 14.1 0.8 2.6 76.5 0.6 0.8 55.3 0.7 1.0 41.1 0.7 1.3 32.0 0.7 1.6 25.0 0.8 2.0 21.2 0.8 2.3 17.6 0.8 2.6 91.8 0.6 0.8 66.3 0.7 1.0 49.3 0.7 1.3 38.3 0.7 1.6 29.9 0.8 2.0 25.4 0.8 2.3 21.1 0.8 2.6 107.1 0.6 0.8 77.4 0.7 1.0 57.5 0.7 1.3 44.7 0.7 1.6 34.9 0.8 2.0 29.7 0.8 2.3 24.6 0.8 2.6 122.4 0.6 0.8 88.4 0.7 1.0 65.7 0.7 1.3 51.1 0.7 1.6 39.9 0.8 2.0 33.9 0.8 2.3 28.1 0.8 2.6 137.8 0.6 0.8 99.5 0.7 1.0 73.9 0.7 1.3 57.5 0.7 1.6 44.9 0.8 2.0 38.0 0.8 2.3 31.6 0.8 2.6 153.1 0.6 0.8 110.6 0.7 1.0 82.1 0.7 1.3 63.9 0.7 1.6 49.9 0.8 2.0 42.2 0.8 2.3 35.1 0.8 2.6 168.4 0.6 0.8 121.6 0.7 1.0 90.3 0.7 1.3 70.3 0.7 1.6 54.9 0.8 2.0 46.4 0.8 2.3 38.6 0.8 2.6 183.7 0.6 0.8 132.7 0.7 1.0 98.5 0.7 1.3 76.7 0.7 1.6 59.9 0.8 2.0 50.7 0.8 2.3 42.1 0.8 2.6 199.0 0.6 0.8 143.7 0.7 1.0 106.7 0.7 1.3 83.1 0.7 1.6 64.8 0.8 2.0 54.9 0.8 2.3 45.6 0.8 2.6 214.3 0.6 0.8 154.8 0.7 1.0 115.0 0.7 1.3 89.4 0.7 1.6 69.8 0.8 2.0 59.1 0.8 2.3 49.1 0.8 2.6 229.6 0.6 0.8 165.8 0.7 1.0 123.2 0.7 1.3 95.8 0.7 1.6 74.8 0.8 2.0 63.3 0.8 2.3 52.6 0.8 2.6 244.9 0.6 0.8 176.9 0.7 1.0 131.4 0.7 1.3 102.2 0.7 1.6 79.8 0.8 2.0 67.6 0.8 2.3 56.1 0.8 2.6 260.2 0.6 0.8 187.9 0.7 1.0 139.6 0.7 1.3 108.6 0.7 1.6 84.8 0.8 2.0 71.8 0.8 2.3 59.6 0.8 2.6 275.5 0.6 0.8 199.0 0.7 1.0 147.8 0.7 1.3 115.0 0.7 1.6 89.8 0.8 2.0 76.0 0.8 2.3 63.1 0.8 2.6 290.8 0.6 0.8 210.0 0.7 1.0 156.0 0.7 1.3 121.4 0.7 1.6 94.8 0.8 2.0 80.2 0.8 2.3 66.6 0.8 2.6 306.1 0.6 0.8 221.1 0.7 1.0 164.2 0.7 1.3 127.8 0.7 1.6 99.8 0.8 2.0 84.4 0.8 2.3 70.1 0.8 2.6 321.4 0.6 0.8 232.2 0.7 1.0 172.4 0.7 1.3 134.2 0.7 1.6 104.7 0.8 2.0 88.7 0.8 2.3 73.6 0.8 2.6 336.7 0.6 0.8 243.2 0.7 1.0 180.6 0.7 1.3 140.5 0.7 1.6 109.7 0.8 2.0 92.9 0.8 2.3 77.1 0.8 2.6 352.0 0.6 0.8 254.3 0.7 1.0 188.8 0.7 1.3 146.9 0.7 1.6 114.7 0.8 2.0 97.1 0.8 2.3 80.6 0.8 2.6 367.3 0.6 0.8 265.3 0.7 1.0 197.1 0.7 1.3 153.3 0.7 1.6 119.7 0.8 2.0 101.3 0.8 2.3 84.1 0.8 2.6 382.6 0.6 0.8 276.4 0.7 1.0 205.3 0.7 1.3 159.7 0.7 1.6 124.7 0.8 2.0 105.5 0.8 2.3 87.6 0.8 2.6 397.9 0.6 0.8 287.4 0.7 1.0 213.5 0.7 1.3 166.1 0.7 1.6 129.7 0.8 2.0 109.8 0.8 2.3 91.1 0.8 2.6 413.2 0.6 0.8 298.5 0.7 1.0 221.7 0.7 1.3 172.5 0.7 1.6 134.7 0.8 2.0 114.0 0.8 2.3 94.6 0.8 2.6 428.6 0.6 0.8 309.5 0.7 1.0 229.9 0.7 1.3 178.9 0.7 1.6 139.7 0.8 2.0 118.2 0.8 2.3 98.1 0.8 2.6 443.9 0.6 0.8 320.6 0.7 1.0 238.1 0.7 1.3 185.3 0.7 1.6 144.6 0.8 2.0 122.4 0.8 2.3 101.7 0.8 2.6 459.2 0.6 0.8 331.7 0.7 1.0 246.3 0.7 1.3 191.6 0.7 1.6 149.6 0.8 2.0 126.7 0.8 2.3 105.2 0.8 2.6

V1=5.5
T D V2
5.7 0.9 2.9 8.7 0.9 3.0 11.8 0.9 3.0 14.7 0.9 3.0 17.7 0.8 3.0 20.6 0.8 3.0 23.5 0.8 3.0 26.5 0.8 3.0 29.4 0.8 3.0 32.3 0.8 3.0 35.3 0.8 3.0 38.2 0.8 3.0 41.2 0.8 3.0 44.1 0.8 3.0 47.0 0.8 3.0 50.0 0.8 3.0 52.9 0.8 3.0 55.8 0.8 3.0 58.8 0.8 3.0 61.7 0.8 3.0 64.7 0.8 3.0 67.6 0.8 3.0 70.5 0.8 3.0 73.5 0.8 3.0 76.4 0.8 3.0 79.3 0.8 3.0 82.3 0.8 3.0 85.2 0.8 3.0 88.2 0.9 3.0

V1=6.0
T D V2
4.7 1.0 3.3 7.3 0.9 3.3 9.8 0.9 3.4 12.5 0.9 3.4 15.0 0.9 3.3 17.5 0.9 3.4 20.0 0.9 3.4 22.5 0.9 3.4 25.0 0.9 3.4 27.5 0.9 3.4 30.0 0.9 3.4 32.5 0.9 3.4 35.0 0.9 3.4 37.4 0.9 3.4 39.8 0.9 3.4 42.3 0.9 3.4 44.8 0.9 3.4 47.3 0.9 3.4 49.7 0.9 3.4 52.2 0.9 3.4 54.7 0.9 3.4 57.2 0.9 3.4 59.7 0.9 3.4 62.2 0.9 3.4 64.7 0.9 3.4 67.2 0.9 3.4 69.6 0.9 3.4 72.1 0.9 3.4 74.6 0.9 3.4

GaSWCC (Amended - 2000)

RETARDANCE "D" AND "B"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

6-219

GaSWCC (Amended - 2000)

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

Table 6-28.2. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "C" Grade 0.25 Percent

V1=2.0 T D V2

V1=2.5 T D V2

V1=3.0 T D V2

V1=3.5 T D V2

V1=4.0 T D V2

V1=4.5 T D V2

V1=5.0 T D V2

V1=5.5 T D V2

V1=6.0 T D V2

9.3 2.3 1.7 11.7 2.2 1.8 14.1 2.1 1.7 16.3 2.1 1.8 18.5 2.1 1.8 10.4 2.8 2.3 20.7 2.1 1.8 12.3 2.6 2.3 22.9 2.1 1.8 13.8 2.6 2.3 25.0 2.0 1.8 15.3 2.5 2.3 27.2 2.0 1.8 16.8 2.5 2.3 10.4 3.4 2.8 29.3 2.0 1.8 18.2 2.5 2.3 12.1 3.1 2.8 31.9 2.0 1.7 19.7 2.4 2.3 13.5 3.0 2.8 34.0 2.0 1.7 21.1 2.4 2.3 14.7 2.9 2.8 36.1 2.0 1.7 22.5 2.4 2.3 15.8 2.9 2.8 38.2 2.0 1.7 23.9 2.4 2.3 16.9 2.8 2.8 40.3 2.0 1.7 25.3 2.4 2.3 18.0 2.8 2.8 42.4 2.0 1.7 26.7 2.4 2.3 19.1 2.8 2.8 44.6 2.0 1.7 28.1 2.4 2.3 20.2 2.8 2.8 46.7 2.0 1.7 29.5 2.4 2.3 21.3 2.8 2.8 12.9 3.8 3.4 48.8 2.0 1.7 30.8 2.4 2.3 22.3 2.8 2.8 14.0 3.7 3.4 50.9 2.0 1.7 32.2 2.4 2.3 23.4 2.8 2.8 15.3 3.5 3.4 53.0 2.0 1.8 33.6 2.4 2.3 24.4 2.8 2.8 16.1 3.5 3.4 55.1 2.0 1.8 35.0 2.4 2.3 25.5 2.8 2.8 16.9 3.4 3.4 57.3 2.0 1.8 36.4 2.4 2.3 26.5 2.7 2.8 17.7 3.4 3.4 59.4 2.0 1.8 38.3 2.4 2.3 27.6 2.7 2.8 18.5 3.4 3.4 61.5 2.0 1.8 39.7 2.4 2.3 28.6 2.7 2.8 19.3 3.3 3.4 63.6 2.0 1.8 41.1 2.4 2.3 29.6 2.7 2.8 20.1 3.3 3.4

T
D
T = Top width, tall vegetation D = Depth, tall vegetation V2 = Design velocity, tall vegetation V1 = Permissible velocity, short vegetation

RETARDANCE "D" AND "C"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

GaSWCC (Amended - 2000)

6-220

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

Table 6-28.2. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "C" Grade 0.50 Percent

V1=2.0 T D V2

V1=2.5 T D V2

V1=3.0 T D V2

V1=3.5 T D V2

V1=4.0 T D V2

V1=4.5 T D V2

V1=5.0 T D V2

V1=5.5 T D V2

V1=6.0 T D V2

8.4 1.6 1.7 11.7 1.5 1.7 7.1 2.0 2.2 14.9 1.5 1.7 9.7 1.8 2.2 18.0 1.5 1.7 12.0 1.7 2.2 21.0 1.5 1.7 14.2 1.7 2.2 9.3 2.1 2.7 24.4 1.5 1.7 16.3 1.7 2.2 10.9 2.0 2.7 27.4 1.5 1.7 18.5 1.7 2.2 12.5 2.0 2.7 30.5 1.5 1.7 20.6 1.7 2.2 14.1 1.9 2.7 8.7 2.6 3.3 33.5 1.5 1.7 22.7 1.7 2.2 15.7 1.9 2.7 10.4 2.4 3.3 36.6 1.5 1.7 24.8 1.7 2.2 17.2 1.9 2.7 11.7 2.3 3.3 39.6 1.5 1.7 27.3 1.7 2.2 18.8 1.9 2.7 12.9 2.3 3.3 42.6 1.5 1.7 29.4 1.7 2.2 20.3 1.9 2.7 14.0 2.2 3.3 9.8 2.8 3.8 45.7 1.5 1.7 31.4 1.7 2.2 21.8 1.9 2.7 15.2 2.2 3.3 11.3 2.7 3.8 48.7 1.5 1.7 33.5 1.7 2.2 23.3 1.9 2.7 16.3 2.2 3.3 12.2 2.6 3.8 51.7 1.5 1.7 35.6 1.6 2.2 24.8 1.9 2.7 17.4 2.2 3.3 13.2 2.5 3.8 54.8 1.5 1.7 37.7 1.6 2.2 26.3 1.9 2.7 18.5 2.2 3.3 14.2 2.5 3.8 57.8 1.5 1.7 39.8 1.6 2.2 27.8 1.9 2.7 19.6 2.2 3.3 15.1 2.5 3.8 60.9 1.5 1.7 41.9 1.6 2.2 29.7 1.9 2.7 20.7 2.2 3.3 16.0 2.5 3.8 11.0 3.2 4.3 63.9 1.5 1.7 44.0 1.6 2.2 31.2 1.9 2.7 21.8 2.2 3.3 16.9 2.5 3.8 12.3 3.0 4.3 66.9 1.5 1.7 46.1 1.6 2.2 32.6 1.9 2.7 22.9 2.2 3.3 17.8 2.4 3.8 13.1 2.9 4.3 70.0 1.5 1.7 48.1 1.6 2.2 34.1 1.9 2.7 24.0 2.1 3.3 18.7 2.4 3.8 13.9 2.9 4.3 73.0 1.5 1.7 50.2 1.6 2.2 35.6 1.9 2.7 25.1 2.1 3.3 19.6 2.4 3.8 14.6 2.9 4.3 76.1 1.5 1.7 52.3 1.6 2.2 37.1 1.9 2.7 26.2 2.1 3.3 20.5 2.4 3.8 15.4 2.8 4.3 79.1 1.5 1.7 54.4 1.6 2.2 38.5 1.9 2.7 27.3 2.1 3.3 21.3 2.4 3.8 16.1 2.8 4.3 82.1 1.5 1.7 56.5 1.6 2.2 40.0 1.9 2.7 28.4 2.1 3.3 22.2 2.4 3.8 16.9 2.8 4.3 85.2 1.5 1.7 58.6 1.6 2.2 41.5 1.9 2.7 29.4 2.1 3.3 23.1 2.4 3.8 17.6 2.8 4.3 88.2 1.5 1.7 60.7 1.6 2.2 43.0 1.9 2.7 30.5 2.1 3.3 24.0 2.4 3.8 18.3 2.8 4.3 12.3 3.7 4.9 91.3 1.5 1.7 62.8 1.6 2.2 44.5 1.9 2.7 31.6 2.1 3.3 24.8 2.4 3.8 19.0 2.7 4.3 13.1 3.5 4.9
RETARDANCE "D" AND "C"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

GaSWCC (Amended - 2000)

Table 6-28.2. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "C" Grade 0.75 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0 T D V2

V1=2.5 T D V2

V1=3.0 T D V2

V1=3.5 T D V2

V1=4.0 T D V2

V1=4.5 T D V2

V1=5.0 T D V2

V1=5.5 T D V2

V1=6.0 T D V2

7.0 1.3 1.6 11.0 1.3 1.6 7.1 1.5 2.1 14.9 1.3 1.6 9.9 1.4 2.1 6.1 1.9 2.6 18.9 1.2 1.6 12.7 1.4 2.1 8.6 1.6 2.7 22.7 1.2 1.6 15.3 1.4 2.1 10.6 1.6 2.6 6.7 2.1 3.2 26.5 1.2 1.6 18.0 1.4 2.1 12.6 1.6 2.7 8.7 1.9 3.2 30.2 1.2 1.6 20.6 1.4 2.1 14.5 1.6 2.7 10.3 1.8 3.2 34.0 1.2 1.6 23.5 1.4 2.1 16.4 1.5 2.7 11.8 1.8 3.2 7.8 2.3 3.8 37.8 1.2 1.6 26.1 1.4 2.1 18.3 1.5 2.7 13.2 1.8 3.2 9.5 2.1 3.8 41.5 1.2 1.6 28.7 1.4 2.1 20.2 1.5 2.7 14.7 1.7 3.2 10.7 2.0 3.8 45.3 1.2 1.6 31.3 1.4 2.1 22.1 1.5 2.7 16.1 1.7 3.2 11.8 2.0 3.8 49.1 1.2 1.6 33.9 1.4 2.1 24.3 1.5 2.6 17.6 1.7 3.2 13.0 2.0 3.8 8.5 2.6 4.4 52.9 1.2 1.6 36.5 1.4 2.1 26.2 1.5 2.6 19.0 1.7 3.2 14.1 2.0 3.8 10.0 2.4 4.3 56.6 1.2 1.6 39.1 1.4 2.1 28.0 1.5 2.6 20.4 1.7 3.2 15.2 2.0 3.8 11.0 2.4 4.4 60.4 1.2 1.6 41.7 1.4 2.1 29.9 1.5 2.6 21.8 1.7 3.2 16.3 1.9 3.8 11.9 2.3 4.4 64.2 1.2 1.6 44.3 1.4 2.1 31.8 1.5 2.6 23.2 1.7 3.2 17.4 1.9 3.8 12.8 2.3 4.4 9.1 2.9 4.8 67.9 1.2 1.6 46.9 1.4 2.1 33.6 1.5 2.6 24.6 1.7 3.2 18.5 1.9 3.8 13.7 2.3 4.4 10.3 2.7 4.8 71.7 1.2 1.6 49.5 1.4 2.1 35.5 1.5 2.6 26.0 1.7 3.2 19.6 1.9 3.8 14.6 2.2 4.4 11.4 2.6 4.8 75.5 1.2 1.6 52.1 1.4 2.1 37.3 1.5 2.6 27.8 1.7 3.2 20.7 1.9 3.8 15.4 2.2 4.4 12.2 2.6 4.8 79.3 1.2 1.6 54.7 1.4 2.1 39.2 1.5 2.6 29.1 1.7 3.2 21.8 1.9 3.8 16.3 2.2 4.4 12.9 2.5 4.8 83.0 1.2 1.6 57.3 1.4 2.1 41.1 1.5 2.6 30.5 1.7 3.2 22.8 1.9 3.8 17.2 2.2 4.4 13.7 2.5 4.8 86.8 1.2 1.6 59.9 1.4 2.1 42.9 1.5 2.6 31.9 1.7 3.2 23.9 1.9 3.8 18.0 2.2 4.4 14.4 2.5 4.8 10.5 3.1 5.3 90.6 1.2 1.6 62.5 1.4 2.1 44.8 1.5 2.7 33.3 1.7 3.2 25.0 1.9 3.8 18.9 2.2 4.4 15.2 2.5 4.8 11.4 3.0 5.3 94.3 1.2 1.6 65.1 1.4 2.1 46.7 1.5 2.7 34.7 1.7 3.2 26.0 1.9 3.8 19.7 2.2 4.4 15.9 2.4 4.8 12.4 2.9 5.3 98.1 1.2 1.6 67.7 1.4 2.1 48.5 1.5 2.7 36.0 1.7 3.2 27.1 1.9 3.8 20.5 2.2 4.4 16.6 2.4 4.8 13.0 2.8 5.3 101.9 1.2 1.6 70.3 1.4 2.1 50.4 1.5 2.7 37.4 1.7 3.2 28.2 1.9 3.8 21.4 2.2 4.4 17.3 2.4 4.8 13.7 2.8 5.3 105.7 1.2 1.6 72.9 1.4 2.1 52.2 1.5 2.7 38.8 1.7 3.2 29.3 1.9 3.8 22.2 2.2 4.4 18.0 2.4 4.9 14.3 2.8 5.3 109.4 1.2 1.6 75.5 1.4 2.1 54.1 1.5 2.7 40.2 1.7 3.2 30.8 1.9 3.7 23.1 2.2 4.4 18.7 2.4 4.9 14.9 2.7 5.3 113.2 1.2 1.6 78.1 1.4 2.1 56.0 1.5 2.7 41.6 1.7 3.2 31.9 1.9 3.7 23.9 2.1 4.4 19.4 2.4 4.9 15.5 2.7 5.3

6-221

RETARDANCE "D" AND "C"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

6-222

Table 6-28.2. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "C" Grade 1.00 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0 T D V2

V1=2.5 T D V2

V1=3.0 T D V2

V1=3.5 T D V2

V1=4.0 T D V2

V1=4.5 T D V2

V1=5.0 T D V2

V1=5.5 T D V2

V1=6.0 T D V2

8.2 1.2 1.6 5.2 1.4 2.0 12.6 1.1 1.6 8.7 1.3 2.1 5.5 1.6 2.6 17.1 1.1 1.6 11.8 1.2 2.1 8.2 1.4 2.6 21.4 1.1 1.6 14.9 1.2 2.1 10.5 1.4 2.6 7.3 1.6 3.1 25.7 1.1 1.6 18.0 1.2 2.1 12.8 1.4 2.6 9.1 1.6 3.2 29.9 1.1 1.6 21.2 1.2 2.1 15.0 1.3 2.6 10.9 1.5 3.1 7.8 1.8 3.7 34.2 1.1 1.6 24.3 1.2 2.1 17.3 1.3 2.6 12.6 1.5 3.1 9.2 1.7 3.7 38.5 1.1 1.6 27.3 1.2 2.1 19.5 1.3 2.6 14.3 1.5 3.1 10.6 1.7 3.7 7.2 2.2 4.3 42.7 1.1 1.6 30.3 1.2 2.1 21.9 1.3 2.6 16.0 1.5 3.2 11.9 1.7 3.7 8.8 2.0 4.3 47.0 1.1 1.6 33.3 1.2 2.1 24.1 1.3 2.6 17.7 1.5 3.2 13.3 1.7 3.7 9.9 1.9 4.3 51.3 1.1 1.6 36.3 1.2 2.1 26.3 1.3 2.6 19.3 1.5 3.2 14.6 1.7 3.7 11.0 1.9 4.3 55.5 1.1 1.6 39.4 1.2 2.1 28.5 1.3 2.6 21.0 1.5 3.2 15.9 1.6 3.7 12.1 1.9 4.3 8.0 2.5 4.9 59.8 1.1 1.6 42.4 1.2 2.1 30.7 1.3 2.6 22.7 1.5 3.2 17.1 1.6 3.7 13.2 1.9 4.3 9.5 2.3 4.8 64.1 1.1 1.6 45.4 1.2 2.1 32.9 1.3 2.6 24.6 1.5 3.1 18.5 1.6 3.7 14.2 1.8 4.3 10.4 2.2 4.9 68.3 1.1 1.6 48.4 1.2 2.1 35.0 1.3 2.6 26.2 1.5 3.1 19.8 1.6 3.7 15.2 1.8 4.3 11.3 2.2 4.9 72.6 1.1 1.6 51.5 1.2 2.1 37.2 1.3 2.6 27.9 1.5 3.1 21.0 1.6 3.7 16.3 1.8 4.3 12.1 2.2 4.9 8.8 2.7 5.4 76.9 1.1 1.6 54.5 1.2 2.1 39.4 1.3 2.6 29.5 1.5 3.1 22.3 1.6 3.7 17.3 1.8 4.3 13.0 2.1 4.9 9.8 2.6 5.4 81.1 1.1 1.6 57.5 1.2 2.1 41.6 1.3 2.6 31.1 1.5 3.1 23.6 1.6 3.7 18.3 1.8 4.3 13.8 2.1 4.9 10.9 2.5 5.3 85.4 1.1 1.6 60.5 1.2 2.1 43.8 1.3 2.6 32.7 1.5 3.1 24.9 1.6 3.7 19.3 1.8 4.3 14.6 2.1 4.9 11.6 2.4 5.4 89.7 1.1 1.6 63.6 1.2 2.1 46.0 1.3 2.6 34.4 1.5 3.1 26.5 1.6 3.7 20.3 1.8 4.3 15.4 2.1 4.9 12.4 2.4 5.4 9.7 2.8 5.8 94.0 1.1 1.6 66.6 1.2 2.1 48.2 1.3 2.6 36.0 1.5 3.1 27.7 1.6 3.7 21.3 1.8 4.3 16.2 2.1 4.9 13.1 2.4 5.4 10.8 2.6 5.8 98.2 1.1 1.6 69.6 1.2 2.1 50.4 1.3 2.6 37.6 1.5 3.1 29.0 1.6 3.7 22.3 1.8 4.3 17.0 2.1 4.9 13.8 2.3 5.4 11.5 2.6 5.8 102.5 1.1 1.6 72.6 1.2 2.1 52.5 1.3 2.6 39.3 1.5 3.1 30.2 1.6 3.7 23.3 1.8 4.3 17.9 2.1 4.9 14.5 2.3 5.4 12.2 2.6 5.8 106.8 1.1 1.6 75.7 1.2 2.1 54.7 1.3 2.6 40.9 1.5 3.1 31.5 1.6 3.7 24.3 1.8 4.3 18.7 2.1 4.9 15.2 2.3 5.4 12.8 2.5 5.8 111.0 1.1 1.6 78.7 1.2 2.1 56.9 1.3 2.6 42.5 1.5 3.1 32.7 1.6 3.7 25.3 1.8 4.3 19.4 2.1 4.9 15.9 2.3 5.4 13.4 2.5 5.8 115.3 1.1 1.6 81.7 1.2 2.1 59.1 1.3 2.6 44.2 1.5 3.1 34.0 1.6 3.7 26.3 1.8 4.3 20.2 2.0 4.9 16.6 2.3 5.4 14.1 2.5 5.8 119.6 1.1 1.6 84.7 1.2 2.1 61.3 1.3 2.6 45.8 1.5 3.1 35.2 1.6 3.7 27.3 1.8 4.3 21.0 2.0 4.9 17.2 2.3 5.4 14.7 2.5 5.8 123.8 1.1 1.6 87.8 1.2 2.1 63.5 1.3 2.6 47.5 1.5 3.1 36.5 1.6 3.7 28.7 1.8 4.3 21.8 2.0 4.9 17.9 2.3 5.4 15.3 2.5 5.8 128.1 1.1 1.6 90.8 1.2 2.1 65.7 1.3 2.6 49.1 1.5 3.1 37.8 1.6 3.7 29.7 1.8 4.3 22.6 2.0 4.9 18.6 2.3 5.4 15.9 2.4 5.8

GaSWCC (Amended - 2000)

RETARDANCE "D" AND "C"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

GaSWCC (Amended - 2000)

Table 6-28.2. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "C" Grade 1.25 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

T D V2 T D V2 4.1 1.2 1.5 9.4 1.0 1.5 6.3 1.2 2.0 14.3 1.0 1.6 9.9 1.1 2.0 19.4 1.0 1.5 13.4 1.1 2.0 24.2 1.0 1.5 17.0 1.1 2.0 29.0 1.0 1.6 20.4 1.1 2.0 33.8 1.0 1.6 23.8 1.1 2.0 38.6 1.0 1.6 27.1 1.1 2.0 43.5 1.0 1.6 30.5 1.1 2.0 48.3 1.0 1.6 33.9 1.1 2.0 53.1 1.0 1.6 37.3 1.1 2.0 57.9 1.0 1.6 40.7 1.1 2.0 62.8 1.0 1.6 44.1 1.1 2.0 67.6 1.0 1.6 47.5 1.1 2.0 72.4 1.0 1.6 50.8 1.1 2.0 77.2 1.0 1.6 54.2 1.1 2.0 82.1 1.0 1.6 57.6 1.1 2.0 86.9 1.0 1.6 61.0 1.1 2.0 91.7 1.0 1.6 64.4 1.1 2.0 96.6 1.0 1.6 67.8 1.1 2.0 101.4 1.0 1.6 71.2 1.1 2.0 106.2 1.0 1.6 74.6 1.1 2.0 111.0 1.0 1.6 78.0 1.1 2.0 115.9 1.0 1.6 81.3 1.1 2.0 120.7 1.0 1.6 84.7 1.1 2.0 125.5 1.0 1.6 88.1 1.1 2.0 130.3 1.0 1.6 91.5 1.1 2.0 135.2 1.0 1.6 94.9 1.1 2.0 140.0 1.0 1.6 98.3 1.1 2.0 144.8 1.0 1.6 101.7 1.1 2.0

V1=3.0 T D V2
6.8 1.3 2.6 9.5 1.2 2.6 12.1 1.2 2.6 14.6 1.2 2.6 17.1 1.2 2.6 19.8 1.2 2.5 22.3 1.2 2.5 24.8 1.2 2.5 27.2 1.2 2.6 29.7 1.2 2.6 32.2 1.2 2.6 34.6 1.2 2.6 37.1 1.2 2.6 39.6 1.2 2.6 42.0 1.2 2.6 44.5 1.2 2.6 47.0 1.2 2.6 49.4 1.2 2.6 51.9 1.2 2.6 54.4 1.2 2.6 56.8 1.2 2.6 59.3 1.2 2.6 61.8 1.2 2.6 64.3 1.2 2.6 66.7 1.2 2.6 69.2 1.2 2.6 71.7 1.2 2.6 74.1 1.2 2.6

V1=3.5 T D V2
6.7 1.4 3.1 8.8 1.4 3.1 10.7 1.4 3.1 12.7 1.3 3.1 14.6 1.3 3.1 16.5 1.3 3.1 18.3 1.3 3.1 20.5 1.3 3.1 22.3 1.3 3.1 24.2 1.3 3.1 26.0 1.3 3.1 27.9 1.3 3.1 29.7 1.3 3.1 31.6 1.3 3.1 33.5 1.3 3.1 35.3 1.3 3.1 37.2 1.3 3.1 39.0 1.3 3.1 40.9 1.3 3.1 42.7 1.3 3.1 44.6 1.3 3.1 46.4 1.3 3.1 48.3 1.3 3.1 50.2 1.3 3.1 52.0 1.3 3.1 53.9 1.3 3.1 55.7 1.3 3.1

V1=4.0 T D V2
5.9 1.7 3.6 7.8 1.6 3.7 9.4 1.5 3.7 10.9 1.5 3.7 12.5 1.5 3.7 13.9 1.5 3.7 15.4 1.5 3.7 16.9 1.5 3.7 18.3 1.5 3.7 19.8 1.4 3.7 21.2 1.4 3.7 23.0 1.4 3.6 24.4 1.4 3.6 25.8 1.4 3.6 27.3 1.4 3.6 28.7 1.4 3.6 30.1 1.4 3.6 31.6 1.4 3.6 33.0 1.4 3.6 34.4 1.4 3.6 35.9 1.4 3.6 37.3 1.4 3.7 38.7 1.4 3.7 40.2 1.4 3.7 41.6 1.4 3.7 43.0 1.4 3.7

V1=4.5 T D V2
6.5 1.9 4.2 8.1 1.7 4.2 9.4 1.7 4.2 10.6 1.7 4.2 11.8 1.6 4.3 13.0 1.6 4.3 14.2 1.6 4.3 15.4 1.6 4.3 16.5 1.6 4.3 17.7 1.6 4.3 18.8 1.6 4.3 20.0 1.6 4.3 21.1 1.6 4.3 22.3 1.6 4.3 23.4 1.6 4.3 24.6 1.6 4.3 26.1 1.6 4.2 27.2 1.6 4.2 28.3 1.6 4.2 29.5 1.6 4.2 30.6 1.6 4.2 31.7 1.6 4.2 32.9 1.6 4.2 34.0 1.6 4.2

V1=5.0 T D V2
7.7 2.0 4.8 9.0 1.9 4.8 10.1 1.9 4.8 11.1 1.8 4.8 12.0 1.8 4.8 13.0 1.8 4.8 14.0 1.8 4.8 14.9 1.8 4.8 15.9 1.8 4.8 16.8 1.8 4.8 17.7 1.8 4.8 18.7 1.8 4.8 19.6 1.7 4.8 20.5 1.7 4.8 21.5 1.7 4.8 22.4 1.7 4.8 23.3 1.7 4.8 24.2 1.7 4.8 25.1 1.7 4.8 26.1 1.7 4.8 27.0 1.7 4.8

V1=5.5 T D V2
8.0 2.3 5.3 9.3 2.1 5.3 10.1 2.1 5.3 11.0 2.0 5.3 11.8 2.0 5.3 12.6 2.0 5.3 13.4 2.0 5.4 14.2 2.0 5.4 15.0 2.0 5.4 15.8 2.0 5.4 16.6 1.9 5.4 17.3 1.9 5.4 18.1 1.9 5.4 18.9 1.9 5.4 19.6 1.9 5.4 20.4 1.9 5.4 21.2 1.9 5.4 21.9 1.9 5.4

V1=6.0 T D V2
9.1 2.5 5.9 10.2 2.4 5.9 10.9 2.3 5.9 11.6 2.3 5.9 12.3 2.3 5.9 13.0 2.2 5.9 13.6 2.2 5.9 14.3 2.2 5.9 14.9 2.2 5.9 15.6 2.2 5.9 16.2 2.2 5.9 16.9 2.2 5.9 17.5 2.2 5.9

6-223

RETARDANCE "D" AND "C"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

6-224

Table 6-28.2. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "C" Grade 1.50 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

T D V2 T D V2 4.9 1.0 1.5 10.5 0.9 1.5 7.1 1.1 2.0 16.0 0.9 1.5 10.9 1.0 2.0 21.3 0.9 1.5 14.7 1.0 2.0 26.6 0.9 1.5 18.6 1.0 2.0 31.9 0.9 1.5 22.3 1.0 2.0 37.3 0.9 1.5 26.0 1.0 2.0 42.6 0.9 1.5 29.7 1.0 2.0 47.9 0.9 1.5 33.4 1.0 2.0 53.2 0.9 1.5 37.1 1.0 2.0 58.5 0.9 1.5 40.8 1.0 2.0 63.8 0.9 1.5 44.5 1.0 2.0 69.2 0.9 1.5 48.2 1.0 2.0 74.5 0.9 1.5 51.9 1.0 2.0 79.8 0.9 1.5 55.6 1.0 2.0 85.1 0.9 1.5 59.4 1.0 2.0 90.4 0.9 1.5 63.1 1.0 2.0 95.8 0.9 1.5 66.8 1.0 2.0 101.1 0.9 1.5 70.5 1.0 2.0 106.4 0.9 1.5 74.2 1.0 2.0 111.7 0.9 1.5 77.9 1.0 2.0 117.0 0.9 1.5 81.6 1.0 2.0 122.4 0.9 1.5 85.3 1.0 2.0 127.7 0.9 1.5 89.0 1.0 2.0 133.0 0.9 1.5 92.7 1.0 2.0 138.3 0.9 1.5 96.4 1.0 2.0 143.6 0.9 1.5 100.1 1.0 2.0 149.0 0.9 1.5 103.9 1.0 2.0 154.3 0.9 1.5 107.6 1.0 2.0 159.6 0.9 1.5 111.3 1.0 2.0

V1=3.0
T D V2
4.6 1.3 2.5 7.8 1.1 2.5 10.6 1.1 2.5 13.4 1.1 2.5 16.2 1.1 2.5 19.1 1.1 2.5 21.8 1.1 2.5 24.5 1.1 2.5 27.3 1.1 2.5 30.0 1.1 2.5 32.7 1.1 2.5 35.4 1.1 2.5 38.2 1.1 2.5 40.9 1.1 2.5 43.6 1.1 2.5 46.3 1.1 2.5 49.0 1.1 2.5 51.8 1.1 2.5 54.5 1.1 2.5 57.2 1.1 2.5 59.9 1.1 2.5 62.6 1.1 2.5 65.4 1.1 2.5 68.1 1.1 2.5 70.8 1.1 2.5 73.5 1.1 2.5 76.3 1.1 2.5 79.0 1.1 2.5 81.7 1.1 2.5

V1=3.5 T D V2
5.3 1.4 3.1 7.7 1.3 3.1 9.9 1.2 3.1 12.0 1.2 3.1 14.1 1.2 3.1 16.2 1.2 3.1 18.3 1.2 3.1 20.6 1.2 3.0 22.7 1.2 3.0 24.7 1.2 3.0 26.8 1.2 3.1 28.8 1.2 3.1 30.9 1.2 3.1 32.9 1.2 3.1 35.0 1.2 3.1 37.1 1.2 3.1 39.1 1.2 3.1 41.2 1.2 3.1 43.2 1.2 3.1 45.3 1.2 3.1 47.3 1.2 3.1 49.4 1.2 3.1 51.4 1.2 3.1 53.5 1.2 3.1 55.6 1.2 3.1 57.6 1.2 3.1 59.7 1.2 3.1 61.7 1.2 3.1

V1=4.0 T D V2
5.1 1.6 3.6 7.3 1.4 3.6 9.0 1.4 3.6 10.7 1.4 3.6 12.4 1.3 3.6 14.0 1.3 3.6 15.7 1.3 3.6 17.3 1.3 3.6 18.9 1.3 3.6 20.8 1.3 3.6 22.4 1.3 3.6 23.9 1.3 3.6 25.5 1.3 3.6 27.1 1.3 3.6 28.7 1.3 3.6 30.3 1.3 3.6 31.9 1.3 3.6 33.5 1.3 3.6 35.1 1.3 3.6 36.7 1.3 3.6 38.3 1.3 3.6 39.9 1.3 3.6 41.4 1.3 3.6 43.0 1.3 3.6 44.6 1.3 3.6 46.2 1.3 3.6 47.8 1.3 3.6

V1=4.5 T D V2
6.6 1.6 4.2 8.1 1.5 4.2 9.5 1.5 4.2 10.8 1.5 4.2 12.1 1.5 4.2 13.4 1.5 4.2 14.7 1.4 4.2 16.0 1.4 4.2 17.3 1.4 4.2 18.6 1.4 4.2 19.9 1.4 4.2 21.2 1.4 4.2 22.8 1.4 4.1 24.0 1.4 4.2 25.3 1.4 4.2 26.5 1.4 4.2 27.8 1.4 4.2 29.1 1.4 4.2 30.3 1.4 4.2 31.6 1.4 4.2 32.8 1.4 4.2 34.1 1.4 4.2 35.3 1.4 4.2 36.6 1.4 4.2 37.9 1.4 4.2

V1=5.0 T D V2

6.9 8.3 9.4 10.5 11.6 12.7 13.7 14.8 15.8 16.9 17.9 18.9 20.0 21.0 22.0 23.1 24.1 25.4 26.4 27.4 28.5 29.5 30.5

1.8 4.7 1.7 4.7 1.7 4.8 1.6 4.8 1.6 4.8 1.6 4.8 1.6 4.8 1.6 4.8 1.6 4.8 1.6 4.8 1.6 4.8 1.6 4.8 1.6 4.8 1.6 4.8 1.6 4.8 1.6 4.8 1.6 478 1.6 4.8 1.6 4.8 1.6 4.8 1.6 4.8 1.6 4.8 1.6 4.8

V1=5.5 T D V2

V1=6.0 T D V2

8.1 1.9 5.3 9.1 1.9 5.3 10.0 1.8 5.3 10.9 1.8 5.3 8.2 2.2 5.8 11.8 1.8 5.3 9.3 2.1 5.8 12.7 1.8 5.3 10.1 2.0 5.9 13.6 1.8 5.3 10.9 2.0 5.9 14.5 1.8 5.3 11.6 2.0 5.9 15.3 1.7 5.3 12.4 2.0 5.9 16.2 1.7 5.3 13 1 1.9 5.9 17.0 1.7 5.3 13.9 1.9 5.9 17.9 1.7 5.3 14.6 1.9 5.9 18.8 1.7 5.3 15.3 1.9 5.9 19.6 1.7 5.3 16.1 1.9 5.9 20.5 1.7 5.3 16.8 1.9 5.9 21.3 1.7 5.3 17.5 1.9 5.9 22.2 1.7 5.3 18.2 1.9 5.9 23.0 1.7 5.3 18.9 1.9 5.9 23.8 1.7 5.3 19.7 1.9 5.9 24.7 1.7 5.3 20.4 1.9 5.9

GaSWCC (Amended - 2000)

RETARDANCE "D" AND "C"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

GaSWCC (Amended - 2000)

Table 6-28.2. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "C" Grade 1.75 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

T D V2 T D V2 5.4 0.9 1.5 11.4 0.9 1.5 7.7 1.0 2.0 17.3 0.9 1.5 11.8 1.0 2.0 23.1 0.9 1.5 16.0 0.9 2.0 28.8 0.9 1.5 20.0 0.9 2.0 34.6 0.9 1.5 24.0 0.9 2.0 40.3 0.9 1.5 28.0 0.9 2.0 46.1 0.9 1.5 32.0 0.9 2.0 51.9 0.9 1.5 36.0 0.9 2.0 57.6 0.9 1.5 40.0 0.9 2.0 63.4 0.9 1.5 44.0 0.9 2.0 69.1 0.9 1.5 48.0 0.9 2.0 74.9 0.9 1.5 52.0 0.9 2.0 80.7 0.9 1.5 56.0 0.9 2.0 86.4 0.9 1.5 60.0 0.9 2.0 92.2 0.9 1.5 63.9 0.9 2.0 97.9 0.9 1.5 67.9 0.9 2.0 103.7 0.9 1.5 71.9 0.9 2.0 109.5 0.9 1.5 75.9 0.9 2.0 115.2 0.9 1.5 79.9 0.9 2.0 121.0 0.9 1.5 83.9 0.9 2.0 126.8 0.9 1.5 87.9 0.9 2.0 132.5 0.9 1.5 91.9 0.9 2.0 138.3 0.9 1.5 95.9 0.9 2.0 144.0 0.9 1.5 99.9 0.9 2.0 149.8 0.9 1.5 103.9 0.9 2.0 155.6 0.9 1.5 107.9 0.9 2.0 161.3 0.9 1.5 111.9 0.9 2.0 167.1 0.9 1.5 115.9 0.9 2.0 172.8 0.9 1.5 119.9 0.9 2.0

V1=3.0
T D V2
5.4 1.1 2.5 8.6 1.1 2.5 11.6 1.0 2.5 14.6 1.0 2.5 17.8 1.0 2.5 20.7 1.0 2.5 23.7 1.0 2.5 26.6 1.0 2.5 29.6 1.0 2.5 32.5 1.0 2.5 35.5 1.0 2.5 38.4 1.0 2.5 41.4 1.0 2.5 44.3 1.0 2.5 47.3 1.0 2.5 50.2 1.0 2.5 53.2 1.0 2.5 56.1 1.0 2.5 59.1 1.0 2.5 62.0 1.0 2.5 65.0 1.0 2.5 67.9 1.0 2.5 70.9 1.0 2.5 73.8 1.0 2.5 76.8 1.0 2.5 79.7 1.0 2.5 82.7 1.0 2.5 85.6 1.0 2.5 88.6 1.0 2.5

V1=3.5 T D V2
6.2 1.2 3.0 8.6 1.2 3.0 10.9 1.1 3.0 13.2 1.1 3.0 15.5 1.1 3.0 18.0 1.1 3.0 20.2 1.1 3.0 22.4 1.1 3.0 24.7 1.1 3.0 26.9 1.1 3.0 29.2 1.1 3.0 31.4 1.1 3.0 33.6 1.1 3.0 35.9 1.1 3.0 38.1 1.1 3.0 40.3 1.1 3.0 42.6 1.1 3.0 44.8 1.1 3.0 47.1 1.1 3.0 49.3 1.1 3.0 51.5 1.1 3.0 53.8 1.1 3.0 56.0 1.1 3.0 58.3 1.1 3.0 60.5 1.1 3.0 62.7 1.1 3.0 65.0 1.1 3.0 67.2 1.1 3.0

V1=4.0 T D V2
6.3 1.3 3.6 8.2 1.3 3.6 10.1 1.2 3.6 11.9 1.2 3.6 13.7 1.2 3.6 15.4 1.2 3.6 17.2 1.2 3.6 19.2 1.2 3.6 20.9 1.2 3.6 22.7 1.2 3.6 24.4 1.2 3.6 26.1 1.2 3.6 27.9 1.2 3.6 29.6 1.2 3.6 31.4 1.2 3.6 33.1 1.2 3.6 34.8 1.2 3.6 36.6 1.2 3.6 38.3 1.2 3.6 40.1 1.2 3.6 41.8 1.2 3.6 43.5 1.2 3.6 45.3 1.2 3.6 47.0 1.2 3.6 48.8 1.2 3.6 50.5 1.2 3.6 52.2 1.2 3.6

V1=4.5 T D V2
5.9 1.5 4.1 7.6 1.4 4.2 9.1 1.4 4.2 10.6 1.4 4.2 12.0 1.3 4.2 13.5 1.3 4.1 14.9 1.3 4.1 16.3 1.3 4.1 17.7 1.3 4.1 19.1 1.3 4.1 20.5 1.3 4.1 22.2 1.3 4.1 23.5 1.3 4.1 24.9 1.3 4.1 26.3 1.3 4.1 27.7 1.3 4.1 29.0 1.3 4.1 30.4 1.3 4.1 31.8 1.3 4.1 33.2 1.3 4.1 34.6 1.3 4.1 35.9 1.3 4.1 37.3 1.3 4.1 38.7 1.3 4.1 40.1 1.3 4.1 41.5 1.3 4.1

V1=5.0 T D V2
6.9 1.6 4.7 8.2 1.6 4.7 9.4 1.5 4.7 10.6 1.5 4.7 11.8 1.5 4.7 12.9 1.5 4.7 14.1 1.5 4.7 15.2 1.5 4.7 16.4 1.4 4.7 17.5 1.4 4.7 18.6 1.4 4.7 19.8 1.4 4.7 20.9 1.4 4.7 22.0 1.4 4.7 23.4 1.4 4.7 24.5 1.4 4.7 25.6 1.4 4.7 26.8 1.4 4.7 27.9 1.4 4.7 29.0 1.4 4.7 30.1 1.4 4.7 31.2 1.4 4.7 32.3 1.4 4.7 33.4 1.4 4.7

V1=5.5 T D V2
7.0 1.8 5.3 8.3 1.7 5.3 9.3 1.7 5.3 10.3 1.6 5.3 11.3 1.6 5.3 12.3 1.6 5.3 13.2 1.6 5.3 14.2 1.6 5.3 15.1 1.6 5.3 16.1 1.6 5.3 17.0 1.6 5.3 17.9 1.6 5.3 18.9 1.6 5.3 19.8 1.6 5.3 20.7 1.6 5.3 21.7 1.6 5.3 22.6 1.6 5.3 23.5 1.6 5.3 24.5 1.6 5.3 25.7 1.6 5.3 26.6 1.6 5.3 27.5 1.6 5.3

V1=6.0 T D V2
6.7 2.1 5.8 8.1 1.9 5.8 9.0 1.9 5.8 9.8 1.8 5.8 10.7 1.8 5.8 11.5 1.8 5.8 12.3 1.8 5.8 13.1 1.8 5.8 13.9 1.7 5.8 14.7 1.7 5.8 15.5 1.7 5.8 16.3 1.7 5.8 17.1 1.7 5.9 17.9 1.7 5.9 18.7 1.7 5.9 19.4 1.7 5.9 20.2 1.7 5.9 21.0 1.7 5.9 21.8 1.7 5.9 22.6 1.7 5.9

6-225

RETARDANCE "D" AND "C"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

6-226

Table 6-28.2. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "C" Grade 2.00 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

T D V2 T D V2 5.9 0.9 1.5 12.4 0.8 1.5 8.1 0.9 2.0 18.5 0.8 1.5 12.3 0.9 2.0 24.7 0.8 1.5 16.7 0.9 2.0 30.8 0.8 1.5 20.8 0.9 2.0 37.0 0.8 1.5 25.0 0.9 2.0 43.2 0.8 1.5 29.1 0.9 2.0 49.3 0.8 1.5 33.3 0.9 2.0 55.5 0.8 1.5 37.4 0.9 2.0 61.7 0.8 1.5 41.6 0.9 2.0 67.8 0.8 1.5 45.7 0.9 2.0 74.0 0.8 1.5 49.9 0.9 2.0 80.2 0.8 1.5 54.0 0.9 2.0 86.3 0.8 1.5 58.2 0.9 2.0 92.5 0.8 1.5 62.3 0.9 2.0 98.7 0.8 1.5 66.5 0.9 2.0 104.8 0.8 1.5 70.6 0.9 2.0 111.0 0.8 1.5 74.8 0.9 2.0 117.2 0.8 1.5 78.9 0.9 2.0 123.3 0.8 1.5 83.1 0.9 2.0 129.5 0.8 1.5 87.3 0.9 2.0 135.7 0.8 1.5 91.4 0.9 2.0 141.8 0.8 1.5 95.6 0.9 2.0 148.0 0.8 1.5 99.7 0.9 2.0 154.1 0.8 1.5 103.9 0.9 2.0 160.3 0.8 1.5 108.0 0.9 2.0 166.5 0.8 1.5 112.2 0.9 2.0 172.6 0.8 1.5 116.3 0.9 2.0 178.8 0.8 1.5 120.5 0.9 2.0 185.0 0.8 1.5 124.6 0.9 2.0

V1=3.0
T D V2
5.9 1.0 2.5 9.3 1.0 2.5 12.5 1.0 2.5 15.9 1.0 2.4 19.0 1.0 2.5 22.2 1.0 2.5 25.3 1.0 2.5 28.5 1.0 2.5 31.7 1.0 2.5 34.8 1.0 2.5 38.0 1.0 2.5 41.1 1.0 2.5 44.3 1.0 2.5 47.5 1.0 2.5 50.6 1.0 2.5 53.8 1.0 2.5 57.0 1.0 2.5 60.1 1.0 2.5 63.3 1.0 2.5 66.4 1.0 2.5 69.6 1.0 2.5 72.8 1.0 2.5 75.9 1.0 2.5 79.1 1.0 2.5 82.3 1.0 2.5 85.4 1.0 2.5 88.6 1.0 2.5 91.8 1.0 2.5 94.9 1.0 2.5

V1=3.5 T D V2
6.8 1.1 3.0 9.4 1.1 3.0 11.8 1.1 3.0 14.3 1.1 3.0 16.9 1.0 3.0 19.3 1.0 3.0 21.7 1.0 3.0 24.1 1.0 3.0 26.5 1.0 3.0 28.9 1.0 3.0 31.4 1.0 3.0 33.8 1.0 3.0 36.2 1.0 3.0 38.6 1.0 3.0 41.0 1.0 3.0 43.4 1.0 3.0 45.8 1.0 3.0 48.2 1.0 3.0 50.6 1.0 3.0 53.0 1.0 3.0 55.4 1.0 3.0 57.9 1.0 3.0 60.3 1.0 3.0 62.7 1.0 3.0 65.1 1.0 3.0 67.5 1.0 3.0 69.9 1.0 3.0 72.3 1.0 3.0

V1=4.0 T D V2
4.7 1.4 3.5 7.0 1.2 3.6 9.0 1.2 3.5 11.0 1.2 3.5 12.9 1.1 3.5 14.8 1.1 3.5 16.7 1.1 3.5 18.8 1.1 3.5 20.7 1.1 3.5 22.6 1.1 3.5 24.5 1.1 3.5 26.3 1.1 3.5 28.2 1.1 3.5 30.1 1.1 3.5 32.0 1.1 3.5 33.8 1.1 3.5 35.7 1.1 3.5 37.6 1.1 3.5 39.5 1.1 3.5 41.3 1.1 3.5 43.2 1.1 3.5 45.1 1.1 3.5 47.0 1.1 3.5 48.8 1.1 3.5 50.7 1.1 3.5 52.6 1.1 3.5 54.5 1.1 3.5 56.4 1.1 3.5

V1=4.5 T D V2
4.7 1.5 4.1 6.8 1.3 4.1 8.5 1.3 4.1 10.1 1.3 4.1 11.6 1.3 4.1 13.1 1.3 4.1 14.7 1.2 4.1 16.2 1.2 4.1 17.7 1.2 4.1 19.5 1.2 4.1 21.0 1.2 4.1 22.4 1.2 4.1 23.9 1.2 4.1 25.4 1.2 4.1 26.9 1.2 4.1 28.4 1.2 4.1 29.9 1.2 4.1 31.4 1.2 4.1 32.9 1.2 4.1 34.4 1.2 4.1 35.9 1.2 4.1 37.4 1.2 4.1 38.9 1.2 4.1 40.3 1.2 4.1 41.8 1.2 4.1 43.3 1.2 4.1 44.8 1.2 4.1

V1=5.0 T D V2
6.4 1.5 4.7 7.8 1.4 4.7 9.1 1.4 4.7 10.4 1.4 4.7 11.7 1.4 4.7 12.9 1.4 4.7 14.1 1.4 4.7 15.4 1.3 4.7 16.6 1.3 4.7 17.8 1.3 4.7 19.0 1.3 4.7 20.3 1.3 4.7 21.8 1.3 4.6 23.0 1.3 4.6 24.2 1.3 4.6 25.4 1.3 4.6 26.6 1.3 4.7 27.9 1.3 4.7 29.1 1.3 4.7 30.3 1.3 4.7 31.5 1.3 4.7 32.7 1.3 4.7 33.9 1.3 4.7 35.1 1.3 4.7 36.3 1.3 4.7

V1=5.5 T D V2
7.1 1.6 5.2 8.2 1.6 5.2 9.3 1.5 5.3 10.4 1.5 5.3 11.4 1.5 5.3 12.4 1.5 5.3 13.5 1.5 5.3 14.5 1.5 5.3 15.5 1.5 5.3 16.5 1.5 5.3 17.5 1.5 5.3 18.6 1.5 5.3 19.6 1.5 5.3 20.6 1.5 5.3 21.6 1.4 5.3 22.6 1.4 5.3 23.9 1.4 5.2 24.8 1.4 5.2 25.8 1.4 5.3 26.8 1.4 5.3 27.8 1.4 5.3 28.8 1.4 5.3 29.8 1.4 5.3

V1=6.0 T D V2
7.1 1.8 5.8 8.2 1.7 5.8 9.2 1.7 5.8 10.1 1.7 5.8 11.0 1.6 5.8 11.8 1.6 5.8 12.7 1.6 5.8 13.6 1.6 5.8 14.4 1.6 5.8 15.3 1.6 5.8 16.2 1.6 5.8 17.0 1.6 5.8 17.9 1.6 5.8 18.7 1.6 5.8 19.5 1.6 5.8 20.4 1.6 5.8 21.2 1.6 5.8 22.1 1.6 5.8 22.9 1.6 5.8 23.7 1.6 5.8 24.6 1.6 5.8

GaSWCC (Amended - 2000)

RETARDANCE "D" AND "C"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

GaSWCC (Amended - 2000)

Table 6-28.2. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "C" Grade 3.00 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

V1=3.0

T D V2 T D V2 T D V2 7.4 0.7 1.4 4.9 0.8 1.9 3.2 1.0 2.3 15.1 0.7 1.4 10.2 0.8 1.9 7.6 0.8 2.4 22.6 0.7 1.4 15.6 0.8 1.9 11.5 0.8 2.4 30.1 0.7 1.4 20.7 0.8 1.9 15.5 0.8 2.4 37.6 0.7 1.4 25.9 0.8 1.9 19.4 0.8 2.4 45.1 0.7 1.4 31.1 0.8 1.9 23.3 0.8 2.4 52.7 0.7 1.4 36.2 0.8 1.9 27.1 0.8 2.4 60.2 0.7 1.4 41.4 0.8 1.9 31.0 0.8 2.4 67.7 0.7 1.4 46.6 0.8 1.9 34.9 0.8 2.4 75.2 0.7 1.4 51.8 0.8 1.9 38.8 0.8 2.4 82.8 0.7 1.4 56.9 0.8 1.9 42.6 0.8 2.4 90.3 0.7 1.4 62.1 0.8 1.9 46.5 0.8 2.4 97.8 0.7 1.4 67.3 0.8 1.9 50.4 0.8 2.4 105.3 0.7 1.4 72.4 0.8 1.9 54.3 0.8 2.4 112.8 0.7 1.4 77.6 0.8 1.9 58.1 0.8 2.4 120.4 0.7 1.4 82.8 0.8 1.9 62.0 0.8 2.4 127.9 0.7 1.4 88.0 0.8 1.9 65.9 0.8 2.4 135.4 0.7 1.4 93.1 0.8 1.9 69.8 0.8 2.4 142.9 0.7 1.4 98.3 0.8 1.9 73.6 0.8 2.4 150.5 0.7 1.4 103.5 0.8 1.9 77.5 0.8 2.4 158.0 0.7 1.4 108.7 0.8 1.9 81.4 0.8 2.4 165.5 0.7 1.4 113.8 0.8 1.9 85.3 0.8 2.4 173.0 0.7 1.4 119.0 0.8 1.9 89.1 0.8 2.4 180.5 0.7 1.4 124.2 0.8 1.9 93.0 0.8 2.4 188.1 0.7 1.4 129.4 0.8 1.9 96.9 0.8 2.4 195.6 0.7 1.4 134.5 0.8 1.9 100.8 0.8 2.4 203.1 0.7 1.4 139.7 0.8 1.9 104.6 0.8 2.4 210.6 0.7 1.4 144.9 0.8 1.9 108.5 0.8 2.4 218.2 0.7 1.4 150.1 0.8 1.9 112.4 0.8 2.4 225.7 0.7 1.4 155.2 0.8 1.9 116.3 0.8 2.4

V1=3.5
T D V2
5.7 0.9 2.9 8.8 0.9 2.9 11.8 0.9 2.9 15.0 0.9 2.9 18.0 0.9 2.9 21.0 0.9 2.9 24.0 0.9 2.9 27.0 0.9 2.9 29.9 0.9 2.9 32.9 0.9 2.9 35.9 0.9 2.9 38.9 0.9 2.9 41.9 0.9 2.9 44.9 0.9 2.9 47.9 0.9 2.9 50.9 0.9 2.9 53.9 0.9 2.9 56.9 0.9 2.9 59.9 0.9 2.9 62.8 0.9 2.9 65.8 0.9 2.9 68.8 0.9 2.9 71.8 0.9 2.9 74.8 0.9 2.9 77.8 0.9 2.9 80.8 0.9 2.9 83.8 0.9 2.9 86.8 0.9 2.9 89.8 0.9 2.9

V1=4.0
T D V2
4.0 1.1 3.4 6.7 1.0 3.4 9.2 0.9 3.4 11.6 0.9 3.4 14.0 0.9 3.4 16.5 0.9 3.4 18.9 0.9 3.4 21.2 0.9 3.4 23.6 0.9 3.4 25.9 0.9 3.4 28.3 0.9 3.4 30.6 0.9 3.4 33.0 0.9 3.4 35.3 0.9 3.4 37.7 0.9 3.4 40.1 0.9 3.4 42.4 0.9 3.4 44.8 0.9 3.4 47.1 0.9 3.4 49.5 0.9 3.4 51.8 0.9 3.4 54.2 0.9 3.4 56.5 0.9 3.4 58.9 0.9 3.4 61.2 0.9 3.4 63.6 0.9 3.4 66.0 0.9 3.4 68.3 0.9 3.4 70.7 0.9 3.4

V1=4.5 T D V2
5.1 1.1 4.0 7.2 1.0 4.0 9.2 1.0 4.0 11.1 1.0 4.0 13.0 1.0 4.0 14.9 1.0 4.0 17.0 1.0 4.0 18.9 1.0 4.0 20.8 1.0 4.0 22.7 1.0 4.0 24.6 1.0 4.0 26.4 1.0 4.0 28.3 1.0 4.0 30.2 1.0 4.0 32.1 1.0 4.0 34.0 1.0 4.0 35.9 1.0 4.0 37.8 1.0 4.0 39.6 1.0 4.0 41.5 1.0 4.0 43.4 1.0 4.0 45.3 1.0 4.0 47.2 1.0 4.0 49.1 1.0 4.0 51.0 1.0 4.0 52.8 1.0 4.0 54.7 1.0 4.0 56.6 1.0 4.0

V1=5.0 T D V2
5.5 1.2 4.6 7.2 1.1 4.6 8.9 1.1 4.6 10.5 1.1 4.6 12.0 1.1 4.6 13.6 1.1 4.6 15.2 1.1 4.6 16.7 1.1 4.6 18.5 1.1 4.5 20.0 1.1 4.5 21.5 1.1 4.5 23.1 1.1 4.5 24.6 1.1 4.5 26.1 1.1 4.5 27.7 1.1 4.5 29.2 1.1 4.5 30.7 1.1 4.5 32.3 1.1 4.5 33.8 1.1 4.6 35.4 1.1 4.6 36.9 1.1 4.6 38.4 1.1 4.6 40.0 1.1 4.6 41.5 1.1 4.6 43.0 1.1 4.6 44.6 1.1 4.6 46.1 1.1 4.6

V1=5.5 T D V2
5.6 1.3 5.1 7.1 1.2 5.2 8.4 1.2 5.2 9.8 1.2 5.2 11.1 1.2 5.2 12.4 1.2 5.2 13.7 1.2 5.2 14.9 1.2 5.2 16.2 1.2 5.2 17.5 1.2 5.2 19.1 1.2 5.1 20.3 1.2 5.1 21.6 1.2 5.1 22.9 1.2 5.1 24.1 1.2 5.1 25.4 1.2 5.1 26.7 1.2 5.1 27.9 1.2 5.1 29.2 1.2 5.1 30.5 1.2 5.1 31.7 1.2 5.1 33.0 1.2 5.1 34.3 1.2 5.1 35.6 1.2 5.1 36.8 1.2 5.1 38.1 1.2 5.1

V1=6.0 T D V2
5.3 1.5 5.7 6.7 1.4 5.7 7.9 1.3 5.7 9.1 1.3 5.7 10.2 1.3 5.7 11.3 1.3 5.7 12.4 1.3 5.7 13.5 1.3 5.7 14.5 1.3 5.7 15.6 1.3 5.7 16.7 1.3 5.7 17.8 1.2 5.7 18.9 1.2 5.7 20.2 1.2 5.7 21.2 1.2 5.7 22.3 1.2 5.7 23.3 1.2 5.7 24.4 1.2 5.7 25.5 1.2 5.7 26.5 1.2 5.7 27.6 1.2 5.7 28.6 1.2 5.7 29.7 1.2 5.7 30.7 1.2 5.7 31.8 1.2 5.7

6-227

RETARDANCE "D" AND "C"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

6-228

Table 6-28.2. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "C" Grade 4.00 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

V1=3.0

V1=3.5

T D V2 T D V2 T D V2 T D V2 8.5 0.6 1.4 5.9 0.7 1.8 4.1 0.8 2.3 17.2 0.6 1.4 12.1 0.7 1.8 8.8 0.7 2.3 6.7 0.8 2.8 25.8 0.6 1.4 18.1 0.7 1.8 13.4 0.7 2.3 10.3 0.8 2.8 34.4 0.6 1.4 24.2 0.7 1.8 17.8 0.7 2.3 13.9 0.8 2.8 43.0 0.6 1.4 30.2 0.7 1.9 22.3 0.7 2.3 17.4 0.8 2.8 51.6 0.6 1.4 36.3 0.7 1.9 26.7 0.7 2.3 20.8 0.8 2.8 60.2 0.6 1.4 42.3 0.7 1.9 31.1 0.7 2.3 24.3 0.8 2.8 68.8 0.6 1.4 48.3 0.7 1.9 35.6 0.7 2.3 27.8 0.8 2.8 77.4 0.6 1.4 54.4 0.7 1.9 40.0 0.7 2.4 31.2 0.8 2.8 86.0 0.6 1.4 60.4 0.7 1.9 44.5 0.7 2.4 34.7 0.8 2.8 94.6 0.6 1.4 66.5 0.7 1.9 48.9 0.7 2.4 38.2 0.8 2.8 103.2 0.6 1.4 72.5 0.7 1.9 53.4 0.7 2.4 41.7 0.8 2.8 111.8 0.6 1.4 78.5 0.7 1.9 57.8 0.7 2.4 45.1 0.8 2.8 120.4 0.6 1.4 84.6 0.7 1.9 62.3 0.7 2.4 48.6 0.8 2.8 129.0 0.6 1.4 90.6 0.7 1.9 66.7 0.7 2.4 52.1 0.8 2.8 137.6 0.6 1.4 96.7 0.7 1.9 71.2 0.7 2.4 55.5 0.8 2.8 146.2 0.6 1.4 102.7 0.7 1.9 75.6 0.7 2.4 59.0 0.8 2.8 154.8 0.6 1.4 108.7 0.7 1.9 80.0 0.7 2.4 62.5 0.8 2.8 163.4 0.6 1.4 114.8 0.7 1.9 84.5 0.7 2.4 65.9 0.8 2.8 172.0 0.6 1.4 120.8 0.7 1.9 88.9 0.7 2.4 69.4 0.8 2.8 180.6 0.6 1.4 126.9 0.7 1.9 93.4 0.7 2.4 72.9 0.8 2.8 189.2 0.6 1.4 132.9 0.7 1.9 97.8 0.7 2.4 76.3 0.8 2.8 197.8 0.6 1.4 138.9 0.7 1.9 102.3 0.7 2.4 79.8 0.8 2.8 206.4 0.6 1.4 145.0 0.7 1.9 106.7 0.7 2.4 83.3 0.8 2.8 215.0 0.6 1.4 151.0 0.7 1.9 111.2 0.7 2.4 86.8 0.8 2.8 223.7 0.6 1.4 157.1 0.7 1.9 115.6 0.7 2.4 90.2 0.8 2.8 232.3 0.6 1.4 163.1 0.7 1.9 120.1 0.7 2.4 93.7 0.8 2.8 240.9 0.6 1.4 169.1 0.7 1.9 124.5 0.7 2.4 97.2 0.8 2.8 249.5 0.6 1.4 175.2 0.7 1.9 129.0 0.7 2.4 100.6 0.8 2.8 258.1 0.6 1.4 181.2 0.7 1.9 133.4 0.7 2.4 104.1 0.8 2.8

V1=4.0
T D V2
5.2 0.9 3.3 8.1 0.8 3.4 10.9 0.8 3.4 13.8 0.8 3.3 16.5 0.8 3.3 19.3 0.8 3.4 22.0 0.8 3.4 24.8 0.8 3.4 27.5 0.8 3.4 30.3 0.8 3.4 33.0 0.8 3.4 35.8 0.8 3.4 38.6 0.8 3.4 41.3 0.8 3.4 44.1 0.8 3.4 46.8 0.8 3.4 49.6 0.8 3.4 52.3 0.8 3.4 55.1 0.8 3.4 57.8 0.8 3.4 60.6 0.8 3.4 63.3 0.8 3.4 66.1 0.8 3.4 68.8 0.8 3.4 71.6 0.8 3.4 74.3 0.8 3.4 77.1 0.8 3.4 79.8 0.8 3.4 82.6 0.8 3.4

V1=4.5
T D V2
3.8 1.0 3.9 6.4 0.9 3.9 8.7 0.9 3.9 10.9 0.9 3.9 13.2 0.9 3.9 15.6 0.9 3.9 17.8 0.9 3.9 20.0 0.9 3.9 22.2 0.9 3.9 24.4 0.9 3.9 26.6 0.9 3.9 28.9 0.9 3.9 31.1 0.9 3.9 33.3 0.9 3.9 35.5 0.9 3.9 37.7 0.9 3.9 39.9 0.9 3.9 42.2 0.9 3.9 44.4 0.9 3.9 46.6 0.9 3.9 48.8 0.9 3.9 51.0 0.9 3.9 53.3 0.9 3.9 55.5 0.9 3.9 57.7 0.9 3.9 59.9 0.9 3.9 62.1 0.9 3.9 64.3 0.9 3.9 66.6 0.9 3.9

V1=5.0 T D V2
4.9 1.0 4.5 6.9 1.0 4.5 8.8 1.0 4.5 10.7 0.9 4.5 12.5 0.9 4.5 14.4 0.9 4.5 16.4 0.9 4.4 18.2 0.9 4.4 20.0 0.9 4.4 21.8 0.9 4.5 23.6 0.9 4.5 25.4 0.9 4.5 27.2 0.9 4.5 29.1 0.9 4.5 30.9 0.9 4.5 32.7 0.9 4.5 34.5 0.9 4.5 36.3 0.9 4.5 38.1 0.9 4.5 39.9 0.9 4.5 41.7 0.9 4.5 43.6 0.9 4.5 45.4 0.9 4.5 47.2 0.9 4.5 49.0 0.9 4.5 50.8 0.9 4.5 52.6 0.9 4.5 54.4 0.9 4.5

V1=5.5 T D V2
5.5 1.1 5.0 7.1 1.0 5.1 8.7 1.0 5.1 10.3 1.0 5.0 11.8 1.0 5.0 13.3 1.0 5.0 14.9 1.0 5.0 16.6 1.0 5.0 18.1 1.0 5.0 19.6 1.0 5.0 21.1 1.0 5.0 22.6 1.0 5.0 24.1 1.0 5.0 25.6 1.0 5.0 27.1 1.0 5.0 28.6 1.0 5.0 30.1 1.0 5.0 31.6 1.0 5.0 33.1 1.0 5.0 34.6 1.0 5.0 36.1 1.0 5.0 37.6 1.0 5.0 39.1 1.0 5.0 40.6 1.0 5.0 42.1 1.0 5.0 43.6 1.0 5.0 45.1 1.0 5.0

V1=6.0 T D V2
5.7 1.2 5.6 7.1 1.1 5.6 8.4 1.1 5.6 9.8 1.1 5.7 11.1 1.1 5.7 12.3 1.1 5.7 13.6 1.1 5.7 14.9 1.1 5.7 16.2 1.1 5.7 17.7 1.1 5.6 19.0 1.1 5.6 20.2 1.1 5.6 21.5 1.1 5.6 22.8 1.1 5.6 24.0 1.1 5.6 25.3 1.1 5.6 26.5 1.1 5.6 27.8 1.1 5.6 29.0 1.1 5.6 30.2 1.1 5.7 31.5 1.1 5.7 32.7 1.1 5.7 34.0 1.1 5.7 35.2 1.1 5.7 36.5 1.1 5.7 37.8 1.1 5.7

GaSWCC (Amended - 2000)

RETARDANCE "D" AND "C"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

GaSWCC (Amended - 2000)

Table 6-28.2. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "C" Grade 5.00 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

V1=3.0

V1=3.5

T D V2 T D V2 T D V2 T D V2 9.5 0.6 1.4 6.7 0.6 1.8 4.7 0.7 2.3 3.5 0.8 2.8 19.0 0.6 1.4 13.7 0.6 1.8 9.7 0.7 2.3 7.6 0.7 2.8 28.5 0.6 1.4 20.5 0.6 1.8 14.8 0.7 2.3 11.7 0.7 2.8 38.0 0.6 1.4 27.3 0.6 1.8 19.7 0.7 2.3 15.5 0.7 2.8 47.5 0.6 1.4 34.1 0.6 1.8 24.6 0.7 2.3 19.4 0.7 2.8 57.0 0.6 1.4 40.9 0.6 1.8 29.5 0.7 2.3 23.3 0.7 2.8 66.5 0.6 1.4 47.7 0.6 1 8 34.4 07 2.3 27.2 0.7 2.8 76.0 0.6 1.4 54.6 0.6 1.8 39.4 0.7 2.3 31.0 0.7 2.8 85.5 0.6 1.4 61.4 0.6 1.8 44.3 0.7 2.3 34.9 0.7 2.8 95.0 0.6 1.4 68.2 0.6 1.8 49.2 0.7 2.3 38.8 0.7 2.8 104.6 0.6 1.4 75.0 0.6 1.8 54.1 0.7 2.3 42.7 0.7 2.8 114.1 0.6 1.4 81.8 0.6 1.8 59.0 0.7 2.3 46.6 0.7 2.8 123.6 0.6 1.4 88.6 0.6 1.8 63.9 0.7 2.3 50.4 0.7 2.8 133.1 0.6 1.4 95.5 0.6 1.8 68.9 0.7 2.3 54.3 0.7 2.8 142.6 0.6 1.4 102.3 0.6 1.8 73.8 0.7 2.3 58.2 0.7 2.8 152.1 0.6 1.4 109.1 0.6 1.8 78.7 0.7 2.3 62.1 0.7 2.8 161.6 0.6 1.4 115.9 0.6 1.8 83.6 0.7 2.3 65.9 0.7 2.8 171.1 0.6 1.4 122.7 0.6 1.8 88.5 0.7 2.3 69.8 0.7 2.8 180.6 0.6 1.4 129.6 0.6 1.8 93.4 0.7 2.3 73.7 0.7 2.8 190.1 0.6 1.4 136.4 0.6 1.8 98.4 0.7 2.3 77.6 0.7 2.8 199.6 0.6 1.4 143.2 0.6 1.8 103.3 0.7 2.3 81.5 0.7 2.8 209.1 0.6 1.4 150.0 0.6 1.8 108.2 0.7 2.3 85.3 0.7 2.8 218.6 0.6 1.4 156.8 0.6 1.8 113.1 0.7 2.3 89.2 0.7 2.8 228.1 0.6 1.4 163.6 0.6 1.8 118.0 0.7 2.3 93.1 0.7 2.8 237.6 0.6 1.4 170.5 0.6 1.8 123.0 0.7 2.3 97.0 0.7 2.8 247.1 0.6 1.4 177.3 0.6 1.8 127.9 0.7 2.3 100.8 0.7 2.8 256.6 0.6 1.4 184.1 0.6 1.8 132.8 0.7 2.3 104.7 0.7 2.8 266.1 0.6 1.4 190.9 0.6 1.8 137.7 0.7 2.3 108.6 0.7 2.8 275.6 0.6 1.4 197.7 0.6 1.8 142.6 0.7 2.3 112.5 0.7 2.8 285.1 0.6 1.4 204.6 0.6 1.8 147.5 0.7 2.3 116.4 0.7 2.8

V1=4.0
T D V2
6.0 0.8 3.3 9.2 0.7 3.3 12.4 0.7 3.3 15.5 0.7 3.3 18.6 0.7 3.3 21.7 0.7 3.3 24.8 0.7 3.3 27.9 0.7 3.3 31.0 0.7 3.3 34.1 0.7 3.3 37.2 0.7 3.3 40.3 0.7 3.3 43.4 0.7 3.3 46.5 0.7 3.3 49.6 0.7 3.3 52.7 0.7 3.3 55.8 0.7 3.3 58.9 0.7 3.3 62.0 0.7 3.3 65.1 0.7 3.3 68.2 0.7 3.3 71.3 0.7 3.3 74.3 0.7 3.3 77.4 0.7 3.3 80.5 0.7 3.3 83.6 0.7 3.3 86.7 0.7 3.3 89.8 0.7 3.3 92.9 0.7 3.3

V1=4.5
T D V2
4.7 0.8 3.8 7.3 0.8 3.8 9.9 0.8 3.8 12.6 0.8 3.8 15.1 0.8 3.8 17.6 0.8 3.8 20.1 0.8 3.8 22.6 0.8 3.8 25.1 0.8 3.8 27.6 0.8 3.8 30.1 0.8 3.8 32.6 0.8 3.8 35.1 0.8 3.8 37.7 0.8 3.8 40.2 0.8 3.8 42.7 0.8 3.8 45.2 0.8 3.8 47.7 0.8 3.8 50.2 0.8 3.8 52.7 0.8 3.8 55.2 0.8 3.8 57.7 0.8 3.8 60.2 0.8 3.8 62.7 0.8 3.8 65.2 0.8 3.8 67.8 0.8 3.8 70.3 0.8 3.8 72.8 0.8 3.8 75.3 0.8 3.8

V1=5.0
T D V2
3.4 1.0 4.4 5.9 0.9 4.4 8.0 0.9 4.4 10.1 0.8 4.4 12.2 0.8 4.4 14.5 0.8 4.4 16.5 0.8 4.4 18.6 0.8 4.4 20.6 0.8 4.4 22.7 0.8 4.4 24.7 0.8 4.4 26.8 0.8 4.4 28.9 0.8 4.4 30.9 0.8 4.4 33.0 0.8 4.4 35.0 0.8 4.4 37.1 0.8 4.4 39.2 0.8 4.4 41.2 0.8 4.4 43.3 0.8 4.4 45.3 0.8 4.4 47.4 0.8 4.4 49.5 0.8 4.4 51.5 0.8 4.4 53.6 0.8 4.4 55.6 0.8 4.4 57.7 0.8 4.4 59.8 0.8 4.4 61.8 0.8 4.4

V1=5.5 T D V2
4.7 1.0 5.0 6.5 0.9 4.9 8.3 0.9 5.0 10.1 0.9 5.0 11.8 09 5.0 13.6 0.9 5.0 15.5 0.9 4.9 17.2 0.9 4.9 18.9 0.9 4.9 20.6 0.9 4.9 22.3 0.9 4.9 24.0 0.9 4.9 25.7 0.9 4.9 27.4 0.9 4.9 29.1 0.9 5.0 30.9 0.9 5.0 32.6 0.9 5.0 34.3 0.9 5.0 36.0 0.9 5.0 37.7 0.9 5.0 39.4 0.9 5.0 41.1 0.9 5.0 42.8 0.9 5.0 44.6 0.9 5.0 46.3 0.9 5.0 48.0 0.9 5.0 49.7 0.9 5.0 51.4 0.9 5.0

V1=6.0 T D V2
5.3 1.0 5.5 6.8 1.0 5.6 8.3 1.0 5.6 9.8 1.0 5.6 11.3 1.0 5.5 12.8 1.0 5.5 14.3 1.0 5.5 15.9 0.9 5.5 17.3 0.9 5.5 18.8 0.9 5.5 20.2 0.9 5.5 21.6 0.9 5.5 23.1 0.9 5.5 24.5 0.9 5.5 26.0 0.9 5.5 27.4 0.9 5.5 28.8 0.9 5.5 30.3 0.9 5.5 31.7 0.9 5.5 33.2 0.9 5.5 34.6 0.9 5.5 36.0 0.9 5.5 37.5 0.9 5.5 38.9 0.9 5.5 40.4 0.9 5.5 41.8 0.9 5.5 43.2 0.9 5.5

6-229

RETARDANCE "D" AND "C"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

6-230

Table 6-28.2. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "C" Grade 6.00 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

V1=3.0

V1=3.5

V1=4.0

T D V2 T D V2 T D V2 T D V2 T D V2 10.6 0.5 1.3 7.3 0.6 1.8 5.3 0.6 2.3 4.0 0.7 2.8 2.9 0.8 3.2 21.1 0.5 1.3 14.7 0.6 1.8 10.9 0.6 2.3 8.4 0.7 2.8 6.6 0.7 3.2 31.6 0.5 1.3 22.1 0.6 1.8 16.3 0.6 2.3 12.7 0.6 2.7 10.1 0.7 3.3 42.1 0.5 1.3 29.5 0.6 1.8 21.7 0.6 2.3 17.0 0.6 2.7 13.6 0.7 3.2 52.7 0.5 1.3 36.8 0.6 1.8 27.1 0.6 2.3 21.2 0.6 2.8 17.0 0.7 3.2 63.2 0.5 1.3 44.2 0.6 1.8 32.5 0.6 2.3 25.4 0.6 2.8 20.4 0.7 3.2 73.7 0.5 1.3 51.6 0.6 1.8 38.0 0.6 2.3 29.7 0.6 2.8 23.8 0.7 3.2 84.2 0.5 1.3 58.9 0.6 1.8 43.4 0.6 2.3 33.9 0.6 2.8 27.2 0.7 3.3 94.8 0.5 1.3 66.3 0.6 1.8 48.8 0.6 2.3 38.2 0.6 2.8 30.7 0.7 3.3 105.3 0.5 1.3 73.6 0.6 1.8 54.2 0.6 2.3 42.4 0.6 2.8 34.1 0.7 3.3 115.8 0.5 1.3 81.0 0.6 1.8 59.7 0.6 2.3 46.6 0.6 2.8 37.5 0.7 3.3 126.4 0.5 1.3 88.4 0.6 1.8 65.1 0.6 2.3 50.9 0.6 2.8 40.9 0.7 3.3 136.9 0.5 1.3 95.7 0.6 1.8 70.5 0.6 2.3 55.1 0.6 2.8 44.3 0.7 3.3 147.4 0.5 1.3 103.1 0.6 1.8 75.9 0.6 2.3 59.3 0.6 2.8 47.7 0.7 3.3 158.0 0.5 1.3 110.5 0.6 1.8 81.3 0.6 2.3 63.6 0.6 2.8 51.1 0.7 3.3 168.5 0.5 1.3 117.8 0.6 1.8 86.8 0.6 2.3 67.8 0.6 2.8 54.5 0.7 3.3 179.0 0.5 1.3 125.2 0.6 1.8 92.2 0.6 2.3 72.0 0.6 2.8 57.9 0.7 3.3 189.6 0.5 1.3 132.6 0.6 1.8 97.6 0.6 2.3 76.3 0.6 2.8 61.3 0.7 3.3 200.1 0.5 1.3 139.9 0.6 1.8 103.0 0.6 2.3 80.5 0.6 2.8 64.7 0.7 3.3 210.6 0.5 1.3 147.3 0.6 1.8 108.5 0.6 2.3 84.8 0.6 2.8 68.1 0.7 3.3 221.1 0.5 1.3 154.6 0.6 1.8 113.9 0.6 2.3 89.0 0.6 2.8 71.5 0.7 3.3 231.7 0.5 1.3 162.0 0.6 1.8 119.3 0.6 2.3 93.2 0.6 2.8 74.9 0.7 3.3 242.2 0.5 1.3 169.4 0.6 1.8 124.7 0.6 2.3 97.5 0.6 2.8 78.3 0.7 3.3 252.7 0.5 1.3 176.7 0.6 1.8 130.2 0.6 2.3 101.7 0.6 2.8 81.7 0.7 3.3 263.3 0.5 1.3 184.1 0.6 1.8 135.6 0.6 2.3 106.0 0.6 2.8 85.1 0.7 3.3 273.8 0.5 1.3 191.5 0.6 1.8 141.0 0.6 2.3 110.2 0.6 2.8 88.5 0.7 3.3 284.3 0.5 1.3 198.8 0.6 1.8 146.4 0.6 2.3 114.4 0.6 2.8 91.9 0.7 3.3 294.9 0.5 1.3 206.2 0.6 1.8 151.8 0.6 2.3 118.7 0.6 2.8 95.3 0.7 3.3 305.4 0.5 1.3 213.6 0.6 1.8 157.3 0.6 2.3 122.9 0.6 2.8 98.7 0.7 3.3 315.9 0.5 1.3 220.9 0.6 1.8 162.7 0.6 2.3 127.1 0.6 2.8 102.1 0.7 3.3

V1=4.5
T D V2
5.3 0.8 3.8 8.2 0.7 3.8 11.1 0.7 3.7 13.9 0.7 3.8 16.6 0.7 3.8 19.4 0.7 3.8 22.2 0.7 3.8 24.9 0.7 3.8 27.7 0.7 3.8 30.5 0.7 3.8 33.3 0.7 3.8 36.0 0.7 3.8 38.8 0.7 3.8 41.6 0.7 3.8 44.3 0.7 3.8 47.1 0.7 3.8 49.9 0.7 3.8 52.6 0.7 3.8 55.4 0.7 3.8 58.2 0.7 3.8 60.9 0.7 3.8 63.7 0.7 3.8 66.5 0.7 3.8 69.3 0.7 3.8 72.0 0.7 3.8 74.8 0.7 3.8 77.6 0.7 3.8 80.3 0.7 3.8 83.1 0.7 3.8

V1=5.0
T D V2
4.2 0.8 4.3 6.6 0.8 4.3 9.0 0.8 4.3 11.3 0.8 4.3 13.7 0.8 4.3 16.0 0.8 4.3 18.3 0.8 4.3 20.6 0.8 4.3 22.8 0.8 4.3 25.1 0.8 4.3 27.4 0.8 4.3 29.7 0.8 4.3 32.0 0.8 4.3 34.3 0.8 4.3 36.5 0.8 4.3 38.8 0.8 4.3 41.1 0.8 4.3 43.4 0.8 4.3 45.7 0.8 4.3 47.9 0.8 4.3 50.2 0.8 4.3 52.5 0.8 4.3 54.8 0.8 4.3 57.1 0.8 4.3 59.4 0.8 4.3 61.6 0.8 4.3 63.9 0.8 4.3 66.2 0.8 4.3 68.5 0.8 4.3

V1=5.5 T D V2
5.4 0.9 4.9 7.4 0.8 4.9 9.3 0.8 4.9 11.3 0.8 4.9 13.4 0.8 4.9 15.3 0.8 4.9 17.2 0.8 4.9 19.1 0.8 4.9 21.0 0.8 4.9 22.9 0.8 4.9 24.8 0.8 4.9 26.7 0.8 4.9 28.6 0.8 4.9 30.5 0.8 4.9 32.4 0.8 4.9 34.3 0.8 4.9 36.2 0.8 4.9 38.1 0.8 4.9 40.0 0.8 4.9 41.9 0.8 4.9 43.8 0.8 4.9 45.7 0.8 4.9 47.6 0.8 4.9 49.5 0.8 4.9 51.4 0.8 4.9 53.3 0.8 4.9 55.2 0.8 4.9 57.1 0.8 4.9

V1=6.0 T D V2
4.3 1.0 5.5 6.1 0.9 5.5 7.8 0.9 5.5 9.4 0.9 5.5 11.1 0.9 5.5 12.7 0.9 5.5 14.5 0.9 5.4 16.1 0.9 5.4 17.7 0.9 5.4 19.3 0.9 5.4 20.9 0.9 5.4 22.5 0.9 5.4 24.1 0.9 5.4 25.7 0.9 5.5 27.3 0.9 5.5 28.9 0.9 5.5 30.5 0.9 5.5 32.1 0.9 5.5 33.7 0.9 5.5 35.3 0.9 5.5 36.9 0.9 5.5 38.5 0.9 5.5 40.1 0.9 5.5 41.7 0.9 5.5 43.3 0.9 5.5 44.9 0.9 5.5 46.5 0.9 5.5 48.1 0.9 5.5

GaSWCC (Amended - 2000)

RETARDANCE "D" AND "C"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

GaSWCC (Amended - 2000)

Table 6-28.2. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "C" Grade 8.00 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

V1=3.0

V1=3.5

V1=4.0

T D V2 T D V2 T D V2 T D V2 T D V2 12.0 0.5 1.3 8.5 0.5 1.7 6.2 0.5 2.2 4.6 0.6 2.7 3.7 0.6 3.2 24.1 0.5 1.3 16.9 0.5 1.7 12.6 0.5 2.2 9.6 0.6 2.7 7.8 0.6 3.2 36.1 0.5 1.3 25.3 0.5 1.7 18.9 0.5 2.2 14.4 0.6 2.7 11.8 0.6 3.2 48.1 0.5 1.3 33.8 0.5 1.7 25.2 0.5 2.2 19.2 0.6 2.7 15.8 0.6 3.2 60.1 0.5 1.3 42.2 0.5 1.7 31.5 0.5 2.2 24.0 0.6 2.7 19.7 0.6 3.2 72.1 0.5 1.3 50.6 0.5 1.7 37.8 0.5 2.2 28.8 0.6 2.7 23.6 0.6 3.2 84.1 0.5 1.3 59.1 0.5 1.7 44.1 0.5 2.2 33.6 0.6 2.7 27.6 0.6 3.2 96.2 0.5 1.3 67.5 0.5 1.7 50.4 0.5 2.2 38.4 0.6 2.7 31.5 0.6 3.2 108.2 0.5 1.3 76.0 0.5 1.7 56.7 0.5 2.2 43.2 0.6 2.7 35.4 0.6 3.2 120.2 0.5 1.3 84.4 0.5 1.7 63.0 0.5 2.2 48.0 0.6 2.7 39.4 0.6 3.2 132.2 0.5 1.3 92.8 0.5 1.7 69.3 0.5 2.2 52.8 0.6 2.7 43.3 0.6 3.2 144.2 0.5 1.3 101.3 0.5 1.7 75.6 0.5 2.2 57.6 0.6 2.7 47.2 0.6 3.2 156.3 0.5 1.3 109.7 0.5 1.7 81.8 0.5 2.2 62.4 0.6 2.7 51.2 0.6 3.2 168.3 0.5 1.3 118.2 0.5 1.7 88.1 0.5 2.2 67.2 0.6 2.7 55.1 0.6 3.2 180.3 0.5 1.3 126.6 0.5 1.7 94.4 0.5 2.2 72.0 0.6 2.7 59.0 0.6 3.2 192.3 0.5 1.3 135.0 0.5 1.7 100.7 0.5 2.2 76.8 0.6 2.7 63.0 0.6 3.2 204.3 0.5 1.3 143.5 0.5 1.7 107.0 0.5 2.2 81.6 0.6 2.7 66.9 0.6 3.2 216.4 0.5 1.3 151.9 0.5 1.7 113.3 0.5 2.2 86.4 0.6 2.7 70.8 0.6 3.2 228.4 0.5 1.3 160.3 0.5 1.7 119.6 0.5 2.2 91.2 0.6 2.7 74.8 0.6 3.2 240.4 0.5 1.3 168.8 0.5 1.7 125.9 0.5 2.2 96.0 0.6 2.7 78.7 0.6 3.2 252.4 0.5 1.3 177.2 0.5 1.7 132.2 0.5 2.2 100.8 0.6 2.7 82.6 0.6 3.2 264.4 0.5 1.3 185.7 0.5 1.7 138.5 0.5 2.2 105.6 0.6 2.7 86.6 0.6 3.2 276.5 0.5 1.3 194.1 0.5 1.7 144.8 0.5 2.2 110.4 0.6 2.7 90.5 0.6 3.2 288.5 0.5 1.3 202.5 0.5 1.7 151.1 0.5 2.2 115.2 0.6 2.7 94.4 0.6 3.2 300.5 0.5 1.3 211.0 0.5 1.7 157.4 0.5 2.2 120.0 0.6 2.7 98.4 0.6 3.2 312.5 0.5 1.3 219.4 0.5 1.7 163.7 0.5 2.2 124.8 0.6 2.7 102.3 0.6 3.2 324.5 0.5 1.3 227.9 0.5 1.7 170.0 0.5 2.2 129.6 0.6 2.7 106.2 0.6 3.2 336.6 0.5 1.3 236.3 0.5 1.7 176.3 0.5 2.2 134.4 0.6 2.7 110.2 0.6 3.2 348.6 0.5 1.3 244.7 0.5 1.7 182.6 0.5 2.2 139.2 0.6 2.7 114.1 0.6 3.2 360.6 0.5 1.3 253.2 0.5 1.7 188.9 0.5 2.2 144.0 0.6 2.7 118.0 0.6 3.2

V1=4.5
T D V2 2.9 0.7 3.6 6.3 0.6 3.7 9.7 0.6 3.7 12.9 0.6 3.7 16.2 0.6 3.7 19.4 0.6 3.7 22.6 0.6 3.7 25.8 0.6 3.7 29.0 0.6 3.7 32.3 0.6 3.7 35.5 0.6 3.7 38.7 0.6 3.7 41.9 0.6 3.7 45.2 0.6 3.7 48.4 0.6 3.7 51.6 0.6 3.7 54.9 0.6 3.7 58.1 0.6 3.7 61.3 0.6 3.7 64.5 0.6 3.7 67.8 0.6 3.7 71.0 0.6 3.7 74.2 0.6 3.7 77.4 0.6 3.7 80.7 0.6 3.7 83.9 0.6 3.7 87.1 0.6 3.7 90.3 0.6 3.7 93.6 0.6 3.7 96.8 0.6 3.7

V1=5.0
T D V2
5.1 0.7 4.2 7.9 0.7 4.2 10.7 0.7 4.2 13.4 0.7 4.2 16.1 0.7 4.2 18.7 0.7 4.2 21.4 0.7 4.2 24.1 0.7 4.2 26.8 0.7 4.2 29.4 0.7 4.2 32.1 0.7 4.2 34.8 0.7 4.2 37.5 0.7 4.2 40.1 0.7 4.2 42.8 0.7 4.2 45.5 0.7 4.2 48.1 0.7 4.2 50.8 0.7 4.2 53.5 0.7 4.2 56.2 0.7 4.2 58.8 0.7 4.2 61.5 0.7 4.2 64.2 0.7 4.2 66.9 0.7 4.2 69.5 0.7 4.2 72.2 0.7 4.2 74.9 0.7 4.2 77.6 0.7 4.2 80.2 0.7 4.2

V1=5.5
T D V2
4.2 0.8 4.8 6.5 0.7 4.8 8.8 0.7 4.8 11.2 0.7 4.7 13.5 0.7 4.8 15.7 0.7 4.8 17.9 0.7 4.8 20.2 0.7 4.8 22.4 0.7 4.8 24.7 0.7 4.8 26.9 0.7 4.8 29.1 0.7 4.8 31.4 0.7 4.8 33.6 0.7 4.8 35.9 0.7 4.8 38.1 0.7 4.8 40.3 0.7 4.8 42.6 0.7 4.8 44.8 0.7 4.8 47.1 0.7 4.8 49.3 0.7 4.8 51.5 0.7 4.8 53.8 0.7 4.8 56.0 0.7 4.8 58.3 0.7 4.8 60.5 0.7 4.8 62.7 0.7 4.8 65.0 0.7 4.8 67.2 0.7 4.8

V1=6.0
T D V2
3.2 0.9 5.3 5.4 0.8 5.3 7.4 0.8 5.3 9.3 0.8 5.3 11.3 0.7 5.3 13.3 0.7 5.3 15.2 0.7 5.3 17.1 0.7 5.3 19.0 0.7 5.3 20.9 0.7 5.3 22.8 0.7 5.3 24.7 0.7 5.3 26.6 0.7 5.3 28.5 0.7 5.3 30.3 0.7 5.3 32.2 0.7 5.3 34.1 0.7 5.3 36.0 0.7 5.3 37.9 0.7 5.3 39.8 0.7 5.3 41.7 0.7 5.3 43.6 0.7 5.3 45.5 0.7 5.3 47.4 0.7 5.3 49.3 0.7 5.3 51.2 0.7 5.3 53.1 0.7 5.3 55.0 0.7 5.3 56.9 0.7 5.3

6-231

RETARDANCE "D" AND "C"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

6-232

Table 6-28.2. Design Chart for Parabolic Vegetated Diversion, Waterway or Stormwater Conveyance (Continued)
V1 FOR RETARDANCE "D", TOP WIDTH (T), DEPTH (D), AND V2 FOR RETARDANCE "C" Grade 10.00 Percent

Q CFS
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

V1=2.0

V1=2.5

V1=3.0

V1=3.5

V1=4.0

V1=4.5

T D V2 T D V2 T D V2 T D V2 T D V2 T D V2 13.3 0.4 1.3 9.4 0.5 1.7 6.8 0.5 2.2 5.3 0.5 2.6 4.1 0.6 3.2 3.4 0.6 3.6 26.6 0.4 1.3 18.7 0.5 1.7 13.8 0.5 2.2 10.9 0.5 2.6 8.5 0.6 3.2 7.1 0.6 3.6 39.9 0.4 1.3 28.0 0.5 1.7 20.7 0.5 2.2 16.3 0.5 2.6 12.8 0.6 3.2 10.9 0.6 3.6 53.2 0.4 1.3 37.4 0.5 1.7 27.6 0.5 2.2 21.7 0.5 2.7 17.0 0.6 3.2 14.5 0.6 3.6 66.5 0.4 1.3 46.7 0.5 1.7 34.5 0.5 2.2 27.1 0.5 2.7 21.3 0.6 3.2 18.1 0.6 3.6 79.8 0.4 1.3 56.1 0.5 1.7 41.4 0.5 2.2 32.5 0.5 2.7 25.5 0.6 3.2 21.7 0.6 3.6 93.1 0.4 1.3 65.4 0.5 1.7 48.3 0.5 2.2 37.9 0.5 2.7 29.8 0.6 3.2 25.3 0.6 3.6 106.4 0.4 1.3 74.7 0.5 1.7 55.2 0.5 2.2 43.3 0.5 2.7 34.0 0.6 3.2 29.0 0.6 3.6 119.7 0.4 1.3 84.1 0.5 1.7 62.1 0.5 2.2 48.8 0.5 2.7 38.3 0.6 3.2 32.6 0.6 3.6 133.0 0.4 1.3 93.4 0.5 1.7 69.0 0.5 2.2 54.2 0.5 2.7 42.5 0.6 3.2 36.2 0.6 3.6 146.3 0.4 1.3 102.8 0.5 1.7 75.9 0.5 2.2 59.6 0.5 2.7 46.8 0.6 3.2 39.8 0.6 3.6 159.6 0.4 1.3 112.1 0.5 1.7 82.8 0.5 2.2 65.0 0.5 2.7 51.0 0.6 3.2 43.4 0.6 3.6 172.9 0.4 1.3 121.4 0.5 1.7 89.7 0.5 2.2 70.4 0.5 2.7 55.3 0.6 3.2 47.1 0.6 3.6 186.2 0.4 1.3 130.8 0.5 1.7 96.6 0.5 2.2 75.8 0.5 2.7 59.5 0.6 3.2 50.7 0.6 3.6 199.5 0.4 1.3 140.1 0.5 1.7 103.5 0.5 2.2 81.2 0.5 2.7 63.8 0.6 3.2 54.3 0.6 3.6 212.8 0.4 1.3 149.5 0.5 1.7 110.5 0.5 2.2 86.7 0.5 2.7 68.0 0.6 3.2 57.9 0.6 3.6 226.1 0.4 1.3 158.8 0.5 1.7 117.4 0.5 2.2 92.1 0.5 2.7 72.3 0.6 3.2 61.5 0.6 3.6 239.4 0.4 1.3 168.1 0.5 1.7 124.3 0.5 2.2 97.5 0.5 2.7 76.5 0.6 3.2 65.2 0.6 3.6 252.7 0.4 1.3 177.5 0.5 1.7 131.2 0.5 2.2 102.9 0.5 2.7 80.8 0.6 3.2 68.8 0.6 3.6 266.0 0.4 1.3 186.8 0.5 1.7 138.1 0.5 2.2 108.3 0.5 2.7 85.0 0.6 3.2 72.4 0.6 3.6 279.3 0.4 1.3 196.2 0.5 1.7 145.0 0.5 2.2 113.7 0.5 2.7 89.3 0.6 3.2 76.0 0.6 3.6 292.6 0.4 1.3 205.5 0.5 1.7 151.9 0.5 2.2 119.2 0.5 2.7 93.5 0.6 3.2 79.6 0.6 3.6 305.9 0.4 1.3 214.9 0.5 1.7 158.8 0.5 2.2 124.6 0.5 2.7 97.8 0.6 3.2 83.3 0.6 3.6 319.2 0.4 1.3 224.2 0.5 1.7 165.7 0.5 2.2 130.0 0.5 2.7 102.0 0.6 3.2 86.9 0.6 3.6 332.5 0.4 1.3 233.5 0.5 1.7 172.6 0.5 2.2 135.4 0.5 2.7 106.3 0.6 3.2 90.5 0.6 3.6 345.8 0.4 1.3 242.9 0.5 1.7 179.5 0.5 2.2 140.8 0.5 2.7 110.5 0.6 3.2 94.1 0.6 3.6 359.1 0.4 1.3 252.2 0.5 1.7 186.4 0.5 2.2 146.2 0.5 2.7 114.8 0.6 3.2 97.7 0.6 3.6 372.4 0.4 1.3 261.6 0.5 1.7 193.3 0.5 2.2 151.7 0.5 2.7 119.0 0.6 3.2 101.3 0.6 3.6 385.7 0.4 1.3 270.9 0.5 1.7 200.2 0.5 2.2 157.1 0.5 2.7 123.3 0.6 3.2 105.0 0.6 3.6 399.0 0.4 1.3 280.2 0.5 1.7 207.1 0.5 2.2 162.5 0.5 2.7 127.5 0.6 3.2 108.6 0.6 3.6

V1=5.0
T D V2 2.6 0.7 4.1 5.9 0.6 4.1 9.0 0.6 4.1 12.1 0.6 4.1 15.1 0.6 4.1 18.1 0.6 4.1 21.1 0.6 4.1 24.1 0.6 4.1 27.2 0.6 4.1 30.2 0.6 4.1 33.2 0.6 4.1 36.2 0.6 4.1 39.2 0.6 4.1 42.2 0.6 4.1 45.2 0.6 4.1 48.3 0.6 4.1 51.3 0.6 4.1 54.3 0.6 4.1 57.3 0.6 4.1 60.3 0.6 4.1 63.3 0.6 4.1 66.4 0.6 4.1 69.4 0.6 4.1 72.4 0.6 4.1 75.4 0.6 4.1 78.4 0.6 4.1 81.4 0.6 4.1 84.4 0.6 4.1 87.5 0.6 4.1 90.5 0.6 4.1

V1=5.5
T D V2
4.9 0.7 4.7 7.5 0.6 4.7 10.2 0.6 4.6 12.7 0.6 4.7 15.2 0.6 4.7 17.8 0.6 4.7 20.3 0.6 4.7 22.8 0.6 4.7 25.4 0.6 4.7 27.9 0.6 4.7 30.5 0.6 4.7 33.0 0.6 4.7 35.5 0.6 4.7 38.1 0.6 4.7 40.6 0.6 4.7 43.1 0.6 4.7 45.7 0.6 4.7 48.2 0.6 4.7 50.7 0.6 4.7 53.3 0.6 4.7 55.8 0.6 4.7 58.3 0.6 4.7 60.9 0.6 4.7 63.4 0.6 4.7 66.0 0.6 4.7 68.5 0.6 4.7 71.0 0.6 4.7 73.6 0.6 4.7 76.1 0.6 4.7

V1=6.0
T D V2
4.0 0.7 5.3 6.3 0.7 5.2 8.5 0.7 5.2 10.8 0.7 5.2 12.9 0.7 5.2 15.1 0.7 5.2 17.2 0.7 5.2 19.4 0.7 5.2 21.5 0.7 5.2 23.7 0.7 5.2 25.9 0.7 5.2 28.0 0.7 5.2 30.2 0.7 5.2 32.3 0.7 5.2 34.5 0.7 5.2 36.6 0.7 5.2 38.8 0.7 5.2 40.9 0.7 5.2 43.1 0.7 5.2 45.2 0.7 5.2 47.4 0.7 5.2 49.5 0.7 5.3 51.7 0.7 5.3 53.8 0.7 5.3 56.0 0.7 5.3 58.1 0.7 5.3 60.3 0.7 5.3 62.5 0.7 5.3 64.6 0.7 5.3

GaSWCC (Amended - 2000)

RETARDANCE "D" AND "C"
NOTE: Width and Depth dimensions are in feet; Velocity measurements are in feet per second; Depth "D" does not include allowance for freeboard or settlement.

GaSWCC (Amended - 2000)

Table 6-28.3. Diversion Design Table D Retardance (V and Trapezoidal Section)

(Based on Handbook of Channel Design, SCS-TP-61)

3:1 Side Slopes "D" Retardance

% Grade Q-cfs
10 20 30 40 60 80 100 120 140 160 180 200 220

2 dA 1.9 11 2.2 15 2.5 19 2.6 20 3.0 27













Triangular

6' bottom width

8' bottom width

3

4

5

2

3

4

5

2

3

4





















dA d Ad Ad Ad Ad Ad Ad AdAdA































1.8 10 1.7 9 1.6 8 1.3 12 1.1 10 1.0 9 0.9 8 1.2 13 1.1 11 1.0 10































2.1 13 1.9 11 1.8 10 1.5 16 1.4 14 1.2 12 1.1 10 1.4 17 1.3 16 1.2 14































2.3 16 2.2 15 2.0 12 1.8 21 1.6 17 1.5 16 1.3 13 1.7 22 1.5 19 1.4 17































2.5 19 2.3 16 2.2 15 2.0 24 1.8 21 1.7 19 1.5 16 1.8 24 1.7 22 1.5 19



























2.8 24 2.7 22 2.5 19 2.3 30 2.1 26 1.9 22 1.7 19 2.1 30 1.9 26 1.8 24

























3.1 29 2.9 25 2.7 22 2.5 34 2.3 30 2.1 26 1.9 22 2.4 37 2.2 32 2.0 28



















3.1 29 2.9 25 2.8 40 2.5 34 2.3 30 2.1 26 2.6 41 2.4 37 2.2 32

















3.0 27 3.0 45 2.8 40 2.5 34 2.3 30 2.8 46 2.5 39 2.3 34











2.9 43 2.6 36 2.4 32 2.9 48 2.7 44 2.5 39





3.0 45 2.8 40 2.6 36 3.1 51 2.9 48 2.7 44



10' bottom width

12' bottom width

5

2

3

4

5

2

3

4

















dA dA dA dAd A dA d Ad A

































0.9 9 1.1 14 1.0 12 0.9 11 0.8 10 1.0 14 0.9 12 0.8 11

















1.1 12 1.3 18 1.2 16 1.0 13 0.9 11 1.2 19 1.1 17 1.0 15































1.2 14 1.5 22 1.4 20 1.2 16 1.1 15 1.3 21 1.2 19 1.2 19



















1.4 17 1.7 26 1.5 22 1.4 20 1.2 16 1.6 27 1.5 25 1.3 21































1.6 21 2.0 32 1.8 28 1.7 26 1.5 22 1.8 31 1.6 27 1.5 25



















1.8 24 2.3 39 2.1 34 1.9 30 1.7 26 2.1 38 1.9 34 1.8 31































2.0 28 2.4 41 2.2 37 2.1 34 1.9 30 2.3 44 2.1 38 1.9 34



















2.1 30 2.6 46 2.4 41 2.2 37 2.0 32 2.5 50 2.3 44 2.1 38





















2.3 34 2.7 49 2.5 44 2.3 39 2.1 34 2.6 52 2.4 46 2.2 41



















2.5 39 2.9 54 2.7 49 2.5 44 2.3 39 2.7 54 2.5 50 2.3 44















2.6 41 3.0 57 2.8 51 2.6 46 2.4 41 2.8 57 2.6 52 2.4 46





2.5 44 2.9 60 2.7 54 2.5 50





3.0 63 2.8 57 2.7 54

5 dA 0.7 10 0.9 13 1.1 17 1.2 19 1.3 21 1.6 27 1.7 29 1.9 34 2.0 36 2.1 38 2.2 41 2.3 44 2.5 50













































NOTE: For diversions built on slopes under 2%, the available cross-sectional area above normal ground will allow a reduction in design depth as follows:
For land slopes of 1% or less, reduce depth of flow (taken from Design Table) 20%.
For land Slopes of 1% to 2%, reduce depth of flow (taken from Design Table) 10%.
For land slopes greater than 2%, use depth of flow taken from Design Table.
For Example: A diversion 6 feet wide with a 2.5 foot depth of flow is required to remove 120 c.f.s. on a 0.4% grade. If this is built on a 1% slope, the depth may be reduced 20%, thus obtaining a flow depth of 2.0 feet. The required crosssectional area of the channel plus that above normal ground line will be 34 square feet corresponding to the 2.5 foot depth. The overall height of diversion will be 2.0 feet plus 0.5 foot freeboard or 2.5 feet, instead of the original 3.0 feet.

6" depth of flow

Freeboard

Approxim3:a1tely

A

d

z

z

Normal ground

b

d = depth of flow, feet b = bottom width of channel, feet A = channel capacity, sq. ft., including area below 0.5' freeboard and excluding
any area less than 0.5' depth of flow z = side slope of channel (horizontal to vertical)
IMPORTANT: To all designed depth of flow add freeboard required by State Standards and Specifications to obtain overall height of terrace above bottom of channel. For final check on cross-sectional area, subtract required freeboard from settled height of diversion and provide for cross-sectional area shown in table.

6-233

6-234

Table 6-28.3. Diversion Design Table D Retardance (V and Trapezoidal Section) (Continued)

(Based on Handbook of Channel Design, SCS-TP-61)

4:1 Side Slopes "D" Retardance

% Grade Q-cfs
10 20 30 40 60 80 100 120 140 160 180 200 220

2 dA 1.8 13 2.1 18 2.4 23 2.5 25 2.8 31 3.1 38

















Triangular

6' bottom width

8' bottom width

10' bottom width

12' bottom width

3

4

5

2

3

4

5

2

3

4

5

2

3

4

5

2

3

4





































dA d Ad Ad Ad Ad Ad Ad AdA dA dA dA dA dAd A dA d Ad A































































1.7 12 1.6 11 1.5 10 1.2 13 1.1 11 1.0 10 0.9 9 1.1 14 1.0 13 0.9 11 08 10 1.1 14 1.0 13 0.9 12 0.8 11 1.0 15 0.9 14 0.8 13















































2.0 16 1.8 13 1.7 12 1.5 18 1.4 16 1.2 13 1.1 11 1.4 19 1.3 17 1.2 15 1.1 14 1.3 20 1.2 18 1.0 14 0.9 12 1.2 20 1.1 18 1.0 16

























































2.2 19 2.1 18 1.9 14 1.8 24 1.6 20 1.5 18 1.3 15 1.7 25 1.5 21 1.4 19 1.2 15 1.5 24 1.4 22 1.2 18 1.1 16 1.3 22 1.2 20 1.2 20





















































2.4 23 2.2 19 2.1 18 1.9 26 1.8 24 1.6 20 1.5 18 1.8 27 1.7 25 1.5 21 1.4 19 1.6 26 1.5 24 1.3 20 1.2 18 1.6 29 1.5 27 1.3 22

























































2.6 27 2.5 25 2.3 21 2.2 33 2.0 28 1.9 26 1.7 22 2.0 32 1.9 30 1.7 25 1.6 23 1.9 33 1.8 31 1.6 26 1.5 24 1.7 32 1.6 29 1.4 25

















































2.9 34 2.7 29 2.5 25 2.4 37 2.2 33 2.1 30 1.9 26 2.3 40 2.1 34 2.0 32 1.8 27 2.2 41 2.0 36 1.8 31 1.6 26 2.0 40 1.9 37 1.7 32

















































3.1 38 2.9 34 2.7 29 2.7 45 2.5 40 2.3 35 2.1 30 2.5 45 2.3 40 2.1 34 1.9 30 2.3 44 2.1 39 2.0 36 1.8 31 2.2 46 2.0 40 1.9 37





































2.8 31 2.9 51 2.7 45 2.4 37 2.2 33 2.7 51 2.5 45 2.3 40 2.1 34 2.5 50 2.3 44 2.2 41 2.0 36 2.4 52 2.2 46 2.0 40





























3.0 54 2.8 48 2.6 43 2.4 37 2.8 54 2.6 48 2.5 45 2.3 40 2.6 53 2.4 47 2.3 44 2.1 39 2.5 55 2.3 49 2.2 46



























3.1 57 2.9 51 2.8 48 2.6 43 3.0 60 2.8 54 2.6 48 2.4 42 2.8 59 2.6 53 2.5 50 2.3 44 2.7 62 2.5 55 2.3 49















2.5 45 2.9 63 2.7 56 2.6 53 2.4 47 2.8 65 2.6 58 2.4 52







2.5 50 2.9 68 2.7 62 2.5 55





3.0 72 2.8 65 2.6 58

5 dA 0.7 12 0.9 14 1.1 18 1.2 20 1.3 22 1.6 29 1.7 32 1.8 35 2.0 40 2.1 43 2.2 46 2.3 49 2.4 52













































6:1 Side Slopes "D" Retardance

% Grade Q-cfs
10 20 30 40 60 80 100 120 140 160 180 200 220 240 260

2 dA 1.6 15 1.9 22 2.1 27 2.3 32 2.5 38 2.7 44 2.9 51 3.0 54



















Triangular

3

4





dA d A





1.5 14 1.4 13









1.8 19 1.6 15







2.0 24 1.8 19







2.2 29 2.0 24







2.3 32 2.2 29







2.5 38 2.4 35





2.7 44 2.6 41



2.8 47 2.7 44

5 dA 1.3 11 1.5 14 1.7 17 1.8 19 2.0 24 2.2 29 2.4 35 2.5 38





























2 dA 1.2 16 1.5 23 1.7 28 1.8 30 2.0 36 2.2 42 2.4 49 2.6 56 2.7 61 2.9 68

























6' bottom width

3

4





dAdA







1.1 14 1.0 12







1.4 20 1.2 16







1.5 23 1.4 20







1.7 28 1.5 23







1.9 33 1.7 28







2.1 39 1.9 33







2.2 42 2.1 39







2.4 49 2.3 46





2.6 56 2.4 49



2.8 64 2.6 56

5 dA 0.9 10 1.1 14 1.2 16 1.4 20 1.6 25 1.8 30 1.9 33 2.1 39 2.3 46 2.5 53



































8' bottom width

10' bottom width

12' bottom width

2

3

4

5

2

3

4

5

2

3

4























dA dA dA dA dA dA dAd A dA d Ad A

































1.1 16 1.0 14 0.9 13 0.8 11 1.1 17 1.0 15 0.9 13 0.8 12 1.0 17 0.9 15 0.8 14



































1.4 23 1.3 21 1.1 16 1.0 14 1.3 21 1.2 20 1.1 18 1.0 16 1.3 25 1.2 23 1.0 17

































1.6 28 1.5 26 1.3 21 1.2 18 1.4 26 1.3 23 1.2 20 1.1 18 1.4 29 1 3 27 1.1 20



































1.7 31 1.6 28 1.4 23 1.3 21 1.5 29 1.4 26 1.3 23 1.2 20 1.5 32 1.4 29 1.3 27































1.9 37 1.8 34 1.6 28 1.5 26 1.8 38 1.7 34 1.5 29 1.4 26 1.6 34 1.5 32 1.4 29





































2.1 43 2.0 40 1.8 34 1.7 31 2.0 44 1.9 41 1.7 34 1.6 31 1.8 41 1.7 37 1.6 34































2.3 50 2.1 43 2.0 40 1.8 34 2.2 51 2.0 44 1.9 41 1.7 34 2.1 51 1.9 45 1.8 41





































2.5 58 2.3 50 2.2 47 2.0 40 2.3 55 2.2 51 2.0 44 1.9 41 2.2 55 2.0 48 1.9 45





























2.6 61 2.5 58 2.3 50 2.2 47 2.5 63 2.3 55 2.2 51 2.0 44 2.4 64 2.2 55 2.1 51



























2.8 67 2.6 61 2.5 58 2.3 50 2.7 71 2.5 63 2.4 59 2.2 51 2.6 70 2.4 64 2.3 59













2.9 71 2.7 64 2.6 61 2.4 54 2.8 75 2.6 67 2.5 63 2.3 55 2.7 76 2.5 68 2.4 63













3.0 72 2.8 67 2.6 61 2.4 54 2.9 79 2.7 77 2.6 67 2.4 59 2.8 81 2.6 72 2.5 68





2.5 58

2.4 59 2.9 85 2.7 76 2.5 68

2.5 63

5 dA 0.7 12 0.9 16 1.0 18 1.2 22 1.3 27 1.5 32 1.6 34 1.7 37 1.9 45 2.1 51 2.2 55 2.3 59 2.3 59 2.4 64 2.5 68

















































GaSWCC (Amended - 2000)



GaSWCC (Amended - 2000)

a

Table 6-28.4. Diversion Design Table C Retardance (V and Trapezoidal Section)

(Based on Handbook of Channel Design, SCS-TP-61)

3:1 Side Slopes "C" Retardance

% Grade
Q 20 30 40 50 60 80 100 120 140 160 180 200 220

2 dA 2.5 19







Triangular

6' bottom width

8' bottom width

10' bottom width

3

4

5

2

3

4

5

2

3

4

5

2

3

4

5

2

































dA d Ad Ad Ad Ad Ad Ad AdAdAdAdAdAdAd AdA



















































2.3 16 2.1 13 1.9 11 1.9 22 1.7 19 1.5 16 1.4 14 1.7 22 1.5 19 1.4 17 1.3 15 1.6 24 1.4 20 1.3 18 1.2 16















































2.5 19 2.3 16 2.2 15 2.0 24 1.8 21 1.7 19 1.5 16 1.9 26 1.7 22 1.5 19 1.4 17 1.7 26 1.5 22 1.4 20 1.3 18 1.6 27











































2.5 19 2.4 17 2.2 28 2.0 24 1.9 22 1.7 19 2.0 28 1.8 24 1.6 21 1.5 19 1.9 30 1.7 26 1.5 22 1.4 20 1.8 31

















































2.5 19 2.3 30 2.1 26 2.0 24 1.8 21 2.2 32 2.0 28 1.8 24 1.6 21 2.0 32 1.8 28 1.6 24 1.5 22 1.9 34





































2.5 34 2.3 30 2.1 26 1.9 22 2.3 34 2.1 30 1.9 26 1.8 24 2.2 37 2.0 32 1.8 28 1.6 24 2.0 36











































2.5 34 2.3 30 2.1 26 2.5 39 2.3 34 2.1 30 1.9 26 2.4 41 2.2 37 2.0 32 1.8 28 2.2 41

























2.5 34 2.3 30



2.5 39 2.3 34 2.1 30







2.4 41 2.2 37 2.0 32 2.5 49















2.5 34

2.5 39 2.3 34





2.3 39 2.1 34













2.4 36



2.5 44 2.3 39







2.4 41



2.5 44



12' bottom width

3

4





d Ad A





































1.4 23 1.3 21 1.6 27 1.5 25 1.7 29 1.6 27 1.8 31 1.7 29 2.0 36 1.9 34 2.2 41 2.0 36 2.4 46 2.2 41
2.3 43 2.4 46























5 dA
1.2 19 1.4 23 1.5 25 1.6 27 1.7 29 1.8 31 2.0 36 2.1 38 2.2 41 2.4 46 2.5 49 2.6 51













































4:1 Side Slopes "C" Retardance

% Grade
Q 30 40 50 60 80 100 120 140 160 180 200 220

2 dA 2.5 25







Triangular

3

4





dA d A





2.4 23 2.3 21









2.5 25 2.4 23





2.5 25



5 dA 2.1 18 2.2 19 2.4 23 2.5 25

















2 dA 2.0 28 2.1 30 2.3 35 2.4 37

















6' bottom width

3

4





dAdA







1.8 24 1.6 20







1.9 26 1.7 22







2.1 30 1.9 26







2.2 33 2.0 28







2.4 37 2.2 33







2.5 40 2.3 35





2.5 40



5 dA 1.5 18 1.6 20 1.7 22 1.9 26 2.0 28 2.2 33 2.4 37 2.5 40





























2 dA 1.8 27 2.0 32 2.1 34 2.3 40 2.5 45



















8' bottom width

3

4





dAdA









1.7 25 1.5 21





1.8 27 1.6 23









1.9 30 1.7 25





2.1 34 1.9 30









2.3 40 2.1 34





2.5 45 2.3 40







2.4 42



2.5 45



5 dA 1.4 19 1.5 21 1.6 23 1.7 25 1.9 30 2.0 32 2.2 37 2.3 40 2.5 45

































10' bottom width

12' bottom width

2

3

4

5

2

3

4















dA dA dAd A dA d Ad A



















1.8 31 1.6 26 1.4 22 1.3 20 1.7 32 1.6 29 1.4 25

























1.9 33 1.7 29 1.5 24 1.4 22 1.8 35 1.7 32 1.5 27





















2.0 36 1.8 31 1.6 26 1.5 24 1.9 37 1.8 35 1.6 29























2.1 39 1.9 34 1.7 29 1.6 26 2.0 40 1.9 37 1.7 32





















2.3 44 2.1 39 1.9 34 1.8 31 2.2 46 2.0 40 1.8 35























2.5 50 2.3 44 2.1 39 1.9 34 2.3 49 2.1 43 2.0 40





















2.5 50 2.3 44 2.1 39 2.5 55 2.3 49 2.2 46













2.4 47 2.2 41



2.5 55 2.3 49











2.5 50 2.3 44

2.4 52









2.4 47



2.5 55







2.5 50

5 dA 1.2 20 1.3 22 1.4 25 1.5 27 1.7 32 1.8 35 2.0 40 2.1 43 2.2 46 2.3 49 2.4 52 2.5 55









































6-235

6-236

Table 6-28.4. Diversion Design Table C Retardance (V and Trapezoidal Section) (Continued)

(Based on Handbook of Channel Design, SCS-TP-61)

6:1 Side Slopes "C" Retardance

% Grade
Q 20 30 40 50 60 80 100 120 140 160 180 200 220

2 dA 2.2 29 2.4 35 2.5 38













Triangular

6' bottom width

8' bottom width

10' bottom width

3

4

5

2

3

4

5

2

3

4

5

2

3

4

5

2

































dA d Ad Ad Ad Ad Ad Ad AdAdAdAdAdAdAd AdA



















































2.1 26 1.9 22 1.8 19 1.8 30 1.7 28 1.6 25 1.4 20 1.7 31 1.6 28 1.5 26 1.3 21 1.6 31 1.5 29 1.4 26 1.2 20 1.5 32















































2.2 29 2.1 26 1.9 22 2.0 36 1.9 33 1.7 28 1.5 23 1.8 34 1.7 31 1.6 28 1.4 23 1.8 38 1.7 34 1.5 29 1.3 23 1.7 37















































2.3 32 2.2 29 2.0 24 2.1 39 2.0 36 1.8 30 1.6 25 2.0 40 1.9 37 1.7 31 1.5 26 1.9 41 1.8 38 1.6 31 1.4 26 1.8 41



















































2.5 38 2.3 32 2.1 26 2.2 42 2.1 39 1.9 33 1.7 28 2.1 43 2.0 40 1.8 34 1.6 28 2.0 44 1.9 41 1.7 34 1.5 29 1.9 45













































2.4 35 2.2 29 2.3 46 2.2 42 2.0 36 1.8 30 2.2 47 2.1 43 1.9 37 1.7 31 2.1 47 2.0 44 1.8 38 1.6 31 2.0 48

















































2.5 38 2.3 32 2.5 53 2.3 46 2.1 39 1.9 33 2.4 54 2.2 47 2.0 40 1.8 34 2.3 55 2.1 47 1.9 41 1.7 34 2.2 55































2.5 38











2.5 53 2.3 46 2.1 39 2.5 58 2.4 54 2.2 47 2.0 40 2.4 59 2.3 55 2.1 47 1.9 41 2.3 59



























2.4 49 2.2 42





2.5 58 2.3 50 2.1 43 2.5 63 2.4 59 2.2 51 2.0 44 2.4 64























2.5 53 2.3 46





2.4 54 2.2 47





2.5 63 2.3 55 2.1 47 2.5 68











2.4 49





2.5 58 2.3 50



2.4 59 2.2 51







2.5 53



2.4 54



2.5 63 2.3 55





2.5 58



2.4 59





2.5 63



12' bottom width

3

4





d Ad A









1.4 29 1.3 27





1.6 34 1.4 29









1.7 37 1.5 32





1.8 41 1.6 34









1.9 45 1.8 41





2.1 52 1.9 45









2.2 55 2.0 48





2.3 59 2.1 52









2.4 64 2.2 55





2.5 68 2.3 59







2.4 64



2.5 68



5 dA 1.2 22 1.3 27 1.3 27 1.4 29 1.6 34 1.7 37 1.8 41 1.9 45 2.0 48 2.1 52 2.2 55 2.2 55 2.3 59













































GaSWCC (Amended - 2000)

APPENDIX A-1
ESTIMATING RUNOFF FROM URBAN AREAS
This appendix contains the USDA Natural Resources Conservation Service's TR-55, Urban Hydrology for Small Watersheds. The pages, tables, and figures listed in the contents are applicable to this section only. This information and TR-55 software is also available on the Internet at
http://www. ftw. nrcs.usda.gov/tech_tools.html

GaSWCC (Amended - 2000)

A-1-1

A-1-2

GaSWCC

Preface
Technical Release 55 (TR-55) presents simplified procedures to calculate storm runoff volume, peak rate of discharge, hydrographs, and storage volumes required for floodwater reservoirs. These procedures are applicable in small watersheds, especially urbanizing watersheds, in the United States. First issued by the Soil Conservation Service (SCS) in January 1975, TR-55 incorporates current SCS procedures. This revision includes results of recent research and other changes based on experience with use of the original edition.
The major revisions and additions are-
1. A flow chart for selecting the appropriate procedure;
2. Three additional rain distributions; 3. Expansion of the chapter on runoff curve num-
bers; 4. A procedure for calculating travel times of
sheet flow; 5. Deletion of a chapter on peak discharges; 6. Modifications to the Graphical Peak Discharge
method and Tabular Hydrograph method; 7. A new storage routing procedure; 8. Features of the TR-55 computer program; and 9. Worksheets.
This revision was prepared by Roger Cronshey, Hydraulic Engineer, Hydrology Unit, SCS, Washington, DC; Dr. Richard H. McCuen, Professor of Civil Engineering, University of Maryland, College Park, MD; Norman Miller, Head, Hydrology Unit, SCS, Washington, DC; Dr. Walter Rawls, Hydrologist, Agricultural Research Service, Beltsville, MD; Sam Robbins (deceased), formerly Hydraulic Engineer, SCS, South National Technical Center (NTC), Fort Worth, TX; and Don Woodward, Hydraulic Engineer, SCS, Northeast NTC, Chester, PA. Valuable contributions were made by John Chenoweth, Stan Hamilton, William Merkel, Robert Rallison (ret.), Harvey Richardson, Wendell Styner, other SCS hydraulic engineers, and Teresa Seeman.
Revised June 1986

GaSWCC

(210-VI-TR-55, Second Ed., June 1986)

i
A-1-3

Contents

Page
Chapter 1: Introduction . . . . . . . . . . . . . . . . . . 1-1 Effects of urban development . . . . . . . . . . . . . . 1-1 Rainfall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 Runoff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 Time parameters . . . . . . . . . . . . . . . . . . . . . . . . 1-2 Peak discharge and hydrographs . . . . . . . . . . . 1-2 Storage effects . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 Selecting the appropriate procedures . . . . . . . . 1-2 Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Chapter 2: Estimating runoff . . . . . . . . . . . . . 2-1 SCS Runoff Curve Number method . . . . . . . . . 2-1 Factors considered in determining runoff curve
numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 Runoff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11 Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11 Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11
Chapter 3: Time of concentration and travel time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Factors affecting time of concentration and travel time . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Computation of travel time and time of concentration . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4 Example 3-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
Chapter 4: Graphical Peak Discharge method 4-1 Peak discharge computation . . . . . . . . . . . . . . . 4-1 Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 Example 4-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
Chapter 5: Tabular Hydrograph method . . . . 5-1 Tabular Hydrograph method exhibits . . . . . . . . . 5-1 Information required for Tabular Hydrograph
method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 Development of composite flood hydrograph . . 5-2 Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3 Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
Chapter 6: Storage volume for detention basins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
Estimating the effect of storage . . . . . . . . . . . . . 6-1 Input requirements and procedures . . . . . . . . . 6-1 Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3 Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3

Page
Appendix A: Hydrologic soil groups . . . . . . . A-1 Disturbed soil profiles . . . . . . . . . . . . . . . . . . . . A-1 Drainage and group D soils . . . . . . . . . . . . . . . . A-1
Appendix B: Synthetic rainfall distributions and rainfall data sources . . . . . . . . . . . . . . . . . . B-1
Synthetic rainfall distributions . . . . . . . . . . . . . . B-1 Rainfall data sources . . . . . . . . . . . . . . . . . . . . . B-3
Appendix C: Computer program . . . . . . . . . . C-1
Appendix D: Worksheets . . . . . . . . . . . . . . . . D-1
Appendix E: References . . . . . . . . . . . . . . . . . E-1
Appendix F: Equations for figures and exhibits . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-1
List of figures . . . . . . . . . . . . . . . . . . . . . . . . . . . iii List of tables . . . . . . . . . . . . . . . . . . . . . . . . . . . iii List of exhibits . . . . . . . . . . . . . . . . . . . . . . . . . . iii List of worksheets . . . . . . . . . . . . . . . . . . . . . . . iv Metric conversions . . . . . . . . . . . . . . . . . . . . . . iv Definitions of symbols . . . . . . . . . . . . . . . . . . . . iv

ii
A-1-4

(210-VI-TR-55, Second Ed., June 1986)

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Figures
Page
1-1. Flow chart for selecting the appropriate procedures in TR-55 . . . . . . . . . . . . . . . . . 1-3
2-1. Solution of runoff equation . . . . . . . . . . . . 2-2 2-2. Flow chart for selecting the appropriate
figure or table for determining runoff curve numbers . . . . . . . . . . . . . . . . . . . . . 2-4 2-3. Composite CN with connected impervious area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10 2-4. Composite CN with unconnected impervious areas and total impervious area less than 30% . . . . . . . . . . . . . . . . . . . . . . 2-10 2-5. Worksheet 2 for example 2-1 . . . . . . . . . . 2-13 2-6. Worksheet 2 for example 2-2 . . . . . . . . . . 2-14 2-7. Worksheet 2 for example 2-3 . . . . . . . . . . 2-15 2-8. Worksheet 2 for example 2-4 . . . . . . . . . . 2-16 3-1. Average velocities for estimating travel time for shallow concentrated flow . . . . . . . . . . 3-2 3-2. Worksheet 3 for example 3-1 . . . . . . . . . . 3-5 4-1. Variation of Ia/P for P and CN . . . . . . . . . . 4-1 4-2. Worksheet 4 for example 4-1 . . . . . . . . . . 4-3 5-1. Worksheet 5a for example 5-1 . . . . . . . . . 5-5 5-2. Worksheet 5b for example 5-1 . . . . . . . . . 5-6 5-3. Worksheet 5a for example 5-2 . . . . . . . . . 5-7 5-4. Worksheet 5b for example 5-2 . . . . . . . . . 5-8 6-1. Approximate detention basin routing for rainfall types I, IA, II, and III . . . . . . . . . . . 6-2 6-2. Worksheet 6a for example 6-1 . . . . . . . . . 6-5 6-3. Worksheet 6a for example 6-2 . . . . . . . . . 6-7 6-4. Worksheet 6b for example 6-3 . . . . . . . . . 6-9 6-5. Worksheet 6a for example 6-4 . . . . . . . . . 6-11 B-1. SCS 24-hour rainfall distributions . . . . . . . B-1 B-2. Approximate geographic boundaries for SCS rainfall distributions . . . . . . . . . . . . . . B-2 B-3. Two-year, 24-hour rainfall . . . . . . . . . . . . . B-4 B-4. Five-year, 24-hour rainfall . . . . . . . . . . . . . B-5 B-5. Ten-year, 24-hour rainfall . . . . . . . . . . . . . B-6 B-6. Twenty-five-year, 24-hour rainfall . . . . . . . B-7 B-7. Fifty-year, 24-hour rainfall . . . . . . . . . . . . . B-8 B-8. One-hundred-year, 24-hour rainfall . . . . . . B-9

Tables

Page

2-1. Runoff depth for selected CN's and rainfall amounts . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
2-2a. Runoff curve numbers for urban areas . . . 2-5 2-2b. Runoff curve numbers for cultivated
agricultural lands . . . . . . . . . . . . . . . . . . . . 2-6 2-2c. Runoff curve numbers for other agricultural
lands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 2-2d. Runoff curve numbers for arid and semi-arid
rangelands . . . . . . . . . . . . . . . . . . . . . . . . 2-8 3-1. Roughness coefficients (Manning's n) for
sheet flow . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 4-1. Ia values for runoff curve numbers . . . . . . . 4-1 4-2. Adjustment factor (F ) for pond and
p
swamp areas that are spread throughout the watershed . . . . . . . . . . . . . . . . . . . . . . 4-2 5-1. I values for runoff curve numbers . . . . . . 5-2
a
F-1. Coefficients for the equation used to generate exhibits 4-I through 4-III . . . . . . . F-2
F-2. Coefficients for the equation used to generate figure 6-1 . . . . . . . . . . . . . . . . . . F-2

Exhibits

4-I: Unit peak discharge (qu) for SCS type I rainfall distribution . . . . . . . . . . . . . . . . . . . 4-4
4-IA: Unit peak discharge (qu) for SCS type IA rainfall distribution . . . . . . . . . . . . . . . . . . . 4-5
4-II: Unit peak discharge (q ) for SCS type II u rainfall distribution . . . . . . . . . . . . . . . . . . . 4-6
4-III: Unit peak discharge (qu) for SCS type III rainfall distribution . . . . . . . . . . . . . . . . . . . 4-7
5-I: Tabular hydrograph unit discharges (csm/in)
for type I rainfall distribution . . . . . . . . . . . 5-9
5-IA: Tabular hydrograph unit discharges (csm/in)
for type IA rainfall distribution . . . . . . . . . . 5-19
5-II: Tabular hydrograph unit discharges (csm/in)
for type II rainfall distribution . . . . . . . . . . . 5-29
5-III: Tabular hydrograph unit discharges (csm/in)
type III rainfall distribution . . . . . . . . . . . . . 5-39
A-1: Hydrologic soil groups for United States
soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3

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(210-VI-TR-55, Second Ed., June 1986)

iii
A-1-5

Worksheets
Page
2: Runoff curve number and runoff . . . . . . . . D-2 3: Time of concentration (Tc) or travel time
(Tt) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-3 4: Graphical Peak Discharge method . . . . . . D-4 5a: Basic watershed data . . . . . . . . . . . . . . . . D-5 5b: Tabular hydrograph discharge summary . . D-6 6a: Detention basin storage, peak outflow
discharge (qo) known . . . . . . . . . . . . . . . . D-7 6b: Detention basin peak outflow, storage
volume (Vs) known . . . . . . . . . . . . . . . . . . D-8
Metric conversions

The English system of units is used in this TR. To convert to the International System of units (metric), use the following factors:

From English unit
Acre Square mile Cubic feet per second Inch Feet per second Acre-foot Cubic foot

To metric unit

Multiply by

Hectare Square kilometer Cubic meters per second Millimeter Meters per second Cubic meter Cubic meter

0.405 2.59 0.0283
25.4 0.3048 1233.489 0.0283

Perform rounding operations as appropriate to indicate the same level of precision as that of the original measurement. For example:
1. A stream discharge is recorded in cubic feet per second with three significant digits.
2. Convert stream discharge to cubic meters per second by multiplying by 0.0283.
3. Round to enough significant digits so that, when converting back to cubic feet per second, you obtain the original value (step 1) with three significant digits.

Definitions of symbols

Symbol Unit

Definition

a

ft2

Cross sectional flow area

Am

mi2

CN

Drainage area Runoff curve number

CNC CNp Emax Fp tor

Composite runoff curve number Pervious runoff curve number Maximum stage Pond and swamp adjustment fac-

Hw

ft

Ia

in

L

ft

Head over weir crest Initial abstraction Flow length

Lw

ft

m

Weir crest length Number of flow segments

n

Manning's roughness coefficient

P

in

Rainfall

Pimp

P2

in

fall

Percent imperviousness Two-year frequency, 24-hour rain-

pw

ft

q

cfs

Wetted perimeter Hydrograph coordinate

qi qo qp qt charge

cfs cfs cfs csm/in

Peak inflow discharge Peak outflow discharge Peak discharge Tabular hydrograph unit dis-

qu

csm/in Unit peak discharge

Q

in

Runoff

r

ft

Hydraulic radius

R

Ratio of unconnected impervious

area to total impervious area

s

ft/ft

Slope of hydraulic grade line

S

in

Potential maximum retention af-

ter

runoff begins

t

hr

Hydrograph time

Tc

hr

Tp

hr

Tt

hr

V

ft/s

Time of concentration Time to peak Travel time Average velocity

Vr

acre-ft, ft3, Runoff volume

or water-

shed-inch

Vs

acre-ft, ft3, Storage volume

or water-

shed-inch

iv
A-1-6

(210-VI-TR-55, Second Ed., June 1986)

GaSWCC

Chapter 1: Introduction
The conversion of rural land to urban land usually increases erosion and the discharge and volume of storm runoff in a watershed. It also causes other problems that affect soil and water. As part of programs established to alleviate these problems, engineers increasingly must assess the probable effects of urban development, as well as design and implement measures that will minimize its adverse effects.
Technical Release 55 (TR-55) presents simplified procedures for estimating runoff and peak discharges in small watersheds. In selecting the appropriate procedure, consider the scope and complexity of the problem, the available data, and the acceptable level of error. While this TR gives special emphasis to urban and urbanizing watersheds, the procedures apply to any small watershed in which certain limitations are met.
Effects of urban development

the total drainage area of the watershed, the location of the development, the effect of any flood control works or other natural or manmade storage, and the time distribution of rainfall during a given storm event.
The model described in TR-55 begins with a rainfall amount uniformly imposed on the watershed over a specified time distribution. Mass rainfall is converted to mass runoff by using a runoff curve number (CN). CN is based on soils, plant cover, amount of impervious areas, interception, and surface storage. Runoff is then transformed into a hydrograph by using unit hydrograph theory and routing procedures that depend on runoff travel time through segments of the watershed.
For a description of the hydrograph development method used by SCS, see chapter 16 of the SCS National Engineering Handbook, Section 4-Hydrology (NEH-4) (SCS 1985). The routing method (Modified AttKin) is explained in appendixes G and H of draft Technical Release 20 (TR-20) (SCS 1983).
Rainfall

An urban or urbanizing watershed is one in which impervious surfaces cover or will soon cover a considerable area. Impervious surfaces include roads, sidewalks, parking lots, and buildings. Natural flow paths in the watershed may be replaced or supplemented by paved gutters, storm sewers, or other elements of artificial drainage.
Hydrologic studies to determine runoff and peak discharge should ideally be based on long-term stationary streamflow records for the area. Such records are seldom available for small drainage areas. Even where they are available, accurate statistical analysis of them is usually impossible because of the conversion of land to urban uses during the period of record. It therefore is necessary to estimate peak discharges with hydrologic models based on measurable watershed characteristics. Only through an understanding of these characteristics and experience in using these models can we make sound judgments on how to alter model parameters to reflect changing watershed conditions.
Urbanization changes a watershed's response to precipitation. The most common effects are reduced infiltration and decreased travel time, which significantly increase peak discharges and runoff. Runoff is determined primarily by the amount of precipitation and by infiltration characteristics related to soil type, soil moisture, antecedent rainfall, cover type, impervious surfaces, and surface retention. Travel time is determined primarily by slope, length of flow path, depth of flow, and roughness of flow surfaces. Peak discharges are based on the relationship of these parameters and on

TR-55 includes four regional rainfall time distributions. See appendix B for a discussion of how these distributions were developed.
All four distributions are for a 24-hour period. This period was chosen because of the general availability of daily rainfall data that were used to estimate 24-hour rainfall amounts. The 24-hour duration spans most of the applications of TR-55.
One critical parameter in the model is time of concentration (T ), which is the time it takes for runoff to
c
travel to a point of interest from the hydraulically most distant point. Normally a rainfall duration equal to or greater than T is used. Therefore, the rainfall distribu-
c
tions were designed to contain the intensity of any duration of rainfall for the frequency of the event chosen. That is, if the 10-year frequency, 24-hour rainfall is used, the most intense hour will approximate the 10-year, 1hour rainfall volume.
Runoff
To estimate runoff from storm rainfall, SCS uses the Runoff Curve Number (CN) method (see chapters 4 through 10 of NEH-4, SCS 1985). Determination of CN depends on the watershed's soil and cover conditions, which the model represents as hydrologic soil group, cover type, treatment, and hydrologic condition. Chapter 2 of this TR discusses the effect of urban development on CN and explains how to use CN to estimate runoff.

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(210-VI-TR-55, Second Ed., June 1986)

1-1 A-1-7

Time parameters
Chapter 3 describes a method for estimating the parameters used to distribute the runoff into a hydrograph. The method is based on velocities of flow through segments of the watershed. Two major parameters are time of concentration (T ) and travel time of flow through the
c
segments (Tt). These and the other parameters used are the same as those used in accepted hydraulic analyses of open channels.
Many methods are empirically derived from actual runoff hydrographs and watershed characteristics. The method in chapter 3 was chosen because it is basic; however, other methods may be used.
Peak discharge and hydrographs
Chapter 4 describes a method for approximating peak rates of discharge, and chapter 5 describes a method for obtaining or routing hydrographs. Both methods were derived from hydrographs prepared by procedures outlined in chapter 16 of NEH-4 (SCS 1985). The computations were made with a computerized SCS hydrologic model, TR-20 (SCS 1983).
The methods in chapters 4 and 5 should be used in accordance with specific guidelines. If basic data are improperly prepared or adjustments not properly used, errors will result.
Storage effects
Chapter 6 outlines procedures to account for the effect of detention-type storage. It provides a shortcut method to estimate temporary flood storage based on hydrologic data developed from the Graphical Peak Discharge or Tabular Hydrograph methods.
By increasing runoff and decreasing travel times, urbanization can be expected to increase downstream peak discharges. Chapter 6 discusses how flood detention can modify the hydrograph so that, ideally, downstream peak discharge is reduced approximately to the predevelopment condition. The shortcuts in chapter 6 are useful in sizing a basin even though the final design may require a more detailed analysis.

Selecting the appropriate procedures
Figure 1-1 is a flow chart that shows how to select the appropriate procedures to use in TR-55. In the figure, the diamond-shaped box labeled "Subareas required?" directs the user to the appropriate method based on whether the watershed needs to be divided into subareas. Watershed subdivision is required when significantly different conditions affecting runoff or timing are present in the watershed - for example, if the watershed has widely differing curve numbers or nonhomogeneous slope patterns.

1-2 A-1-8

(210-VI-TR-55, Second Ed., June 1986)

GaSWCC

Graphical Peak
Discharge method

START

Data to

No

estimate

Tc ?

Yes

Hydrograph

Yes

required?

No

No

Subareas

Yes

required?

TR-55 not
applicable
Tabular Hydrograph
method

Compute watershed
runoff (chapter 2)
Compute watershed
Tc (chapter 3)
Compute peak
discharge (chapter 4)

Storage

Yes

effect

required?

No

END

Compute subareas'
runoff (chapter 2)
Compute subareas' Tc and Tt (chapter 3)
Compute tabular
hydrograph (chapter 5)
Compute starage effect (chapter 6)

GaSWCC

Figure 1-1. - Flow Chart for Selecting the Appropriate Procedures in TR-55 (210-VI-TR-55, Second Ed., June 1986)

1-3 A-1-9

Limitations
To save time, the procedures in TR-55 are simplified by assumptions about some parameters. These simplifications, however, limit the use of the procedures and can provide results that are less accurate than more detailed methods. The user should examine the sensitivity of the analysis being conducted to a variation of the peak discharge or hydrograph. To ensure that the degree of error is tolerable, specific limitations are given in chapters 2 through 6. Additional general constraints to the use of TR-55 are as follows:
The methods in this TR are based on open and unconfined flow over land or in channels. For large events during which flow is divided between sewer and overland flow, more information about hydraulics than is presented here is needed to determine Tc. After flow enters a closed system, the discharge can be assumed constant until another flow is encountered at a junction or another inlet.

Both the Graphical Peak Discharge and Tabular Hydrograph methods are derived from TR-20 (SCS 1983) output. Their accuracy is comparable; they differ only in their products. The use of Tc permits them to be used for any size watershed within the scope of the curves or tables. The Graphical method (chapter 4) is used only for hydrologically homogeneous watersheds because the procedure is limited to a single watershed subarea. The Tabular method (chapter 5) can be used for a heterogeneous watershed that is divided into a number of homogeneous subwatersheds. Hydrographs for the subwatersheds can be routed and added.
The approximate storage-routing curves (chapter 6) should not be used if the adjustment for ponding (chapter 4) is used. These storage-routing curves, like the peak discharge and hydrograph procedures, are generalizations derived from TR-20 routings.

1-4 A-1-10

(210-VI-TR-55, Second Ed., June 1986)

GaSWCC

Chapter 2: Estimating runoff

SCS Runoff Curve Number method

The SCS Runoff Curve Number (CN) method is described in detail in NEH-4 (SCS 1985). The SCS runoff equation is

Q = (P - Ia)2 (P - Ia) + S
where

[Eq. 2-1]

Q = runoff (in), P = rainfall (in), S = potential maximum retention after runoff
begins (in), and Ia = initial abstraction (in).
Initial abstraction (I ) is all losses before runoff bea
gins. It includes water retained in surface depressions, water intercepted by vegetation, evaporation, and infiltration. I is highly variable but generally is correlated
a
with soil and cover parameters. Through studies of many small agricultural watersheds, Ia was found to be approximated by the following empirical equation:

Ia = 0.2S.

[Eq. 2-2]

By removing Ia as an independent parameter, this approximation allows use of a combination of S and P
to produce a unique runoff amount. Substituting equa-
tion 2-2 into equation 2-1 gives

Q =(P - 0.2S)2. (P + 0.8S)

[Eq. 2-3]

S is related to the soil and cover conditions of the watershed through the CN. CN has a range of 0 to 100, and S is related to CN by

S = 1000 -10. nCNn

[Eq. 2-4]

Figure 2-1 and table 2-1 solve equations 2-3 and 2-4 for a range of CN's and rainfall.

Factors considered in determining runoff curve numbers
The major factors that determine CN are the hydrologic soil group (HSG), cover type, treatment, hydrologic condition, and antecedent runoff condition (ARC). Another factor considered is whether impervious areas outlet directly to the drainage system (connected) or whether the flow spreads over pervious areas before entering the drainage system (unconnected). Figure 22 is provided to aid in selecting the appropriate figure or table for determining curve numbers.
CN's in table 2-2 (a to d) represent average antecedent runoff condition for urban, cultivated agricultural, other agricultural, and arid and semiarid rangeland uses. Table 2-2 assumes impervious areas are directly connected. The following sections explain how to determine CN's and how to modify them for urban conditions.
Hydrologic soil groups
Infiltration rates of soils vary widely and are affected by subsurface permeability as well as surface intake rates. Soils are classified into four HSG's (A, B, C, and D) according to their minimum infiltration rate, which is obtained for bare soil after prolonged wetting. Appendix A defines the four groups, and the Manual for Erosion and Sediment Control in Georgia, Appendix B-1, provides a list of most of the soils and their group classifications. The soils in the area of interest may be identified from a soil survey report, which can be obtained from local SCS offices or soil and water conservation district offices.
Most urban areas are only partially covered by impervious surfaces: the soil remains an important factor in runoff estimates. Urbanization has a greater effect on runoff in watersheds with soils having high infiltration rates (sands and gravels) than in watersheds predominantly of silts and clays, which generally have low infiltration rates.
Any disturbance of a soil profile can significantly change its infiltration characteristics. With urbanization, native soil profiles may be mixed or removed or fill material from other areas may be introduced. Therefore, a method based on soil texture is given in appendix A for determining the HSG classification for disturbed soils.

GaSWCC

(210-VI-TR-55, Second Ed., June 1986)

2-1 A-1-11

2-2 A-1-12

Direct runoff (Q), inches

Figure 2-1. - Solution of Runoff Equation (210-VI-TR-55, Second Ed., June 1986)

8

Curves on this sheet are for

7

the case Ia = 0.2S, so that

(P-0.2S)2

6 5

Q = P+0.8S

Curve number = 100

95

90

85 80

75

70

4

65

60

55

3

50

45

2

40

1

0

0

1

2

3

4

5

6

7

8

9

10

11

12

Rainfall (P), inches

GaSWCC

Cover type
Table 2-2 addresses most cover types, such as vegetation, bare soil, and impervious surfaces. There are a number of methods for determining cover type.The most common are field reconnaissance, aerial photographs, and land use maps.
Treatment
Treatment is a cover type modifier (used only in table 2-2b) to describe the management of cultivated agricultural lands. It includes mechanical practices, such as contouring and terracing, and management practices, such as crop rotations and reduced or no tillage.

Hydrologic condition
Hydrologic condition indicates the effects of cover type and treatment on infiltration and runoff and is generally estimated from density of plant and residue cover on sample areas. Good hydrologic condition indicates that the soil usually has a low runoff potential for that specific hydrologic soil group, cover type, and treatment. Some factors to consider in estimating the effect of cover on infiltration and runoff are (a) canopy or density of lawns, crops, or other vegetative areas; (b) amount of year-round cover; (c) amount of grass or close-seeded legumes in rotations; (d) percent of residue cover; and (e) degree of surface roughness.

Table 2-1. - Runoff Depth for Selected CN's and Rainfall Amounts1

Runoff depth for curve number of-

Rainfall 40 45 50

55 60 65 70 75 80

85 90 95 98

------------------------------------------------------------------------ inches ---------------------------------------------------------------------

-

1.0

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.03 0.08 0.17 0.32 0.56 0.79

1.2

.00 .00 .00 .00 .00 .00 .03 .07 .15 .27 .46 .74 .99

1.4

.00 .00 .00 .00 .00 .02 .06 .13 .24 .39 .61 .92 1.18

1.6

.00 .00 .00 .00 .01 .05 .11 .20 .34 .52 .76 1.11 1.38

1.8

.00 .00 .00 .00 .03 .09 .17 .29 .44 .65 .93 1.29 1.58

2.0

.00 .00 .00 .02 .06 .14 .24 .38 .56 .80 1.09 1.48 1.77

2.5

.00 .00 .02 .08 .17 .30 .46 .65 .89 1.18 1.53 1.96 2.27

3.0

.00 .02 .09 .19 .33 .51 .71 .96 1.25 1.59 1.98 2.45 2.77

3.5

.02 .08 .20 .35 .53 .75 1.01 1.30 1.64 2.02 2.45 2.94 3.27

4.0

.06 .18 .33 .53 .76 1.03 1.33 1.67 2.04 2.46 2.92 3.43 3.77

4.5

.14 .30 .50 .74 1.02 1.33 1.67 2.05 2.46 2.91 3.40 3.92 4.26

5.0

.24 .44 .69 .98 1.30 1.65 2.04 2.45 2.89 3.37 3.88 4.42 4.76

6.0

.50 .80 1.14 1.52 1.92 2.35 2.81 3.28 3.78 4.30 4.85 5.41 5.76

7.0

.84 1.24 1.68 2.12 2.60 3.10 3.62 4.15 4.69 5.25 5.82 6.41 6.76

8.0

1.25 1.74 2.25 2.78 3.33 3.89 4.46 5.04 5.63 6.21 6.81 7.40 7.76

9.0

1.71 2.29 2.88 3.49 4.10 4.72 5.33 5.95 6.57 7.18 7.79 8.40 8.76

10.0

2.23 2.89 3.56 4.23 4.90 5.56 6.22 6.88 7.52 8.16 8.78 9.40 9.76

11.0

2.78 3.52 4.26 5.00 5.72 6.43 7.13 7.81 8.48 9.13 9.77 10.39 10.76

12.0

3.38 4.19 5.00 5.79 6.56 7.32 8.05 8.76 9.45 10.11 10.76 11.39 11.76

13.0

4.00 4.89 5.76 6.61 7.42 8.21 8.98 9.71 10.42 11.10 11.76 12.39 12.76

14.0

4.65 5.62 6.55 7.44 8.30 9.12 9.91 10.67 11.39 12.08 12.75 13.39 13.76

15.0

5.33 6.36 7.35 8.29 9.19 10.04 10.85 11.63 12.37 13.07 13.74 14.39 14.76

1 Interpolate the values shown to obtain runoff depths for CN's or rainfall amounts not shown.

GaSWCC

(210-VI-TR-55, Second Ed., June 1986)

2-3 A-1-13

START

No

Unconnected

impervious

area?

Yes

No

Impervious

Yes

area

<30%?

Table 2-2

No

assumptions

apply?

Yes

Determine composite
CN
(table 2-2)

Determine pervious
CN (table 2-2)
Determine composite
CN (figure 2-3)

Determine pervious
CN (table 2-2)
Determine composite
CN (figure 2-4)

END
Figure 2-2. - Flow Chart for Selecting the Appropriate Figure or Table for Determining Runoff Curve Numbers

2-4 A-1-14

(210-VI-TR-55, Second Ed., June 1986)

GaSWCC

Table 2-2a. - Runoff Curve Numbers for Urban Areas1

Cover description Cover type and hydrologic condition

Average percent

impervious area2

A

Curve numbers for hydrologic soil group-

B

C

D

Fully developed urban areas (vegetation established)

Open space (lawns, parks, golf courses, cemeteries,

etc.)3:

Poor condition (grass cover < 50%) . . . . . . . . .

Fair condition (grass cover 50% to 75%) . . . . .

Good condition (grass cover > 75%) . . . . . . . . .

Impervious areas:

Paved parking lots, roofs, driveways, etc.

(excluding right-of-way) . . . . . . . . . . . . . . . . . . .

Streets and roads:

Paved; curbs and storm sewers (excluding

right-of-way) . . . . . . . . . . . . . . . . . . . . . . . . . .

Paved; open ditches (including right-of-way) . . .

Gravel (including right-of-way) . . . . . . . . . . . . .

Dirt (including right-of-way) . . . . . . . . . . . . . . . .

Western desert urban areas:

Natural desert landscaping (pervious areas only)4

Artificial desert landscaping (impervious weed

barrier, desert shrub with 1- to 2-inch sand

or gravel mulch and basin borders) . . . . . . . . . .

Urban districts:

Commercial and business . . . . . . . . . . . . . . . . . .

85

Industrial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

72

Residential districts by average lot size:

1/8 acre or less (town houses) . . . . . . . . . . . . . .

65

1/4 acre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

38

1/3 acre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

30

1/2 acre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

25

1 acre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

20

2 acres . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12

Developing urban areas

Newly graded areas (pervious areas only, no vegetation)5 . . . . . . . . . . . . . . . . . . . . . . . . . .
Idle lands (CN's are determined using cover types similar to those in table 2-2c).

68

79

86

89

49

69

79

84

39

61

74

80

98

98

98

98

98

98

98

98

83

89

92

93

76

85

89

91

72

82

87

89

63

77

85

88

96

96

96

96

89

92

94

95

81

88

91

93

77

85

90

92

61

75

83

87

57

72

81

86

54

70

80

85

51

68

79

84

46

65

77

82

77

86

91

94

1 Average runoff condition, and Ia = 0.2S. 2 The average percent impervious area shown was used to develop the composite CN's. Other assumptions are as follows: impervious areas are directly connected to the drainage system, impervious areas have a CN of 98, and pervious areas are considered equivalent to open space in good hydrologic condition. CN's for other combinations of conditions may be computed using figure 2-3 or 2-4. 3 CN's shown are equivalent to those of pasture. Composite CN's may be computed for other combinations of open space cover type. 4 Composite CN's for natural desert landscaping should be computed using figures 2-3 or 2-4 based on the impervious area percentage (CN = 98) and the pervious area CN. The pervious area CN's are assumed equivalent to desert shrub in poor hydrologic condition. 5 Composite CN's to use for the design of temporary measures during grading and construction should be computed using figure 2-3 or 2-4, based on the degree of development (impervious area percentage) and the CN's for the newly graded pervious areas.

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(210-VI-TR-55, Second Ed., June 1986)

2-5 A-1-15

Table 2-2b. - Runoff Curve Numbers for Cultivated Agricultural Lands1

Cover type

Cover description Treatment2

Hydrologic condition3

Curve numbers for hydrologic soil group-

A

B

C

D

Fallow Row crops
Small grain
Close-seeded or broadcast legumes or rotation meadow

Bare soil Crop residue cover (CR) Straight row (SR) SR + CR Contoured (C) C + CR Contoured & terraced (C&T) C&T + CR SR SR + CR C C + CR C&T C&T + CR SR C C&T

Poor Good Poor Good Poor Good Poor Good Poor Good Poor Good Poor Good Poor Good Poor Good Poor Good Poor Good Poor Good Poor Good Poor Good Poor Good Poor Good

77

86

91

94

76

85

90

93

74

83

88

90

72

81

88

91

67

78

85

89

71

80

87

90

64

75

82

85

70

79

84

88

65

75

82

86

69

78

83

87

64

74

81

85

66

74

80

82

62

71

78

81

65

73

79

81

61

70

77

80

65

76

84

88

63

75

83

87

64

75

83

86

60

72

80

84

63

74

82

85

61

73

81

84

62

73

81

84

60

72

80

83

61

72

79

82

59

70

78

81

60

71

78

81

58

69

77

80

66

77

85

89

58

72

81

85

64

75

83

85

55

69

78

83

63

73

80

83

51

67

76

80

1 Average runoff condition, and Ia = 0.2S. 2 Crop residue cover applies only if residue is on at least 5% of the surface throughout the year. 3 Hydrologic condition is based on combination of factors that affect infiltration and runoff, including (a) density and canopy of vegetative areas, (b) amount of year-round cover, (c) amount of grass or close-seeded legumes in rotations, (d) percent of residue cover on the land surface (good > 20%), and (e) degree of surface roughness.
Poor: Factors impair infiltration and tend to increase runoff. Good: Factors encourage average and better than average infiltration and tend to decrease runoff.

2-6 A-1-16

(210-VI-TR-55, Second Ed., June 1986)

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Table 2-2c. - Runoff Curve Numbers for Other Agricultural Lands1

Cover type

Cover description

Hydrologic condition

Curve numbers for hydrologic soil group-

A

B

C

D

Pasture, grassland, or range - continuous forage for grazing.2
Meadow - continuous grass, protected from grazing and generally mowed for hay.
Brush - brush-weed-grass mixture with brush the major element.3
Woods - grass combination (orchard or tree farm).5
Woods.6
Farmsteads - buildings, lanes, driveways, and surrounding lots.

Poor Fair Good
-
Poor Fair Good
Poor Fair Good
Poor Fair Good
-

68

79

86

89

49

69

79

84

39

61

74

80

30

58

71

78

48

67

77

83

35

56

70

77

430

48

65

73

57

73

82

86

43

65

76

82

32

58

72

79

45

66

77

83

36

60

73

79

430

55

70

77

59

74

82

86

1 Average runoff condition, and Ia = 0.2S.
2 Poor: < 50% ground cover or heavily grazed with no mulch. Fair: 50 to 75% ground cover and not heavily grazed. Good: >75% ground cover and lightly or only occasionally grazed.
3 Poor: < 50% ground cover. Fair: 50 to 75% ground cover. Good: > 75% ground cover.
4 Actual curve number is less than 30; use CN = 30 for runoff computations.
5 CN's shown were computed for areas with 50% woods and 50% grass (pasture) cover. Other combinations of conditions may be computed from the CN's for woods and pasture.
6 Poor: Forest litter, small trees, and brush are destroyed by heavy grazing or regular burning. Fair: Woods are grazed but not burned, and some forest litter covers the soil. Good: Woods are protected from grazing, and litter and brush adequately cover the soil.

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(210-VI-TR-55, Second Ed., June 1986)

2-7 A-1-17

Table 2-2d. - Runoff Curve Numbers for Arid and Semiarid Rangelands1

Cover description Cover type

Hydrologic condition2

Curve numbers for hydrologic soil group-

A3

B

C

D

Herbaceous - mixture of grass, weeds, and low-growing brush, with brush the minor element.
Oak - aspen-mountain brush mixture of oak brush, aspen, mountain mahogany, bitter brush, maple, and other brush.
Pinyon - juniper-pinyon, juniper, or both; grass understory.
Sagebrush with grass understory.
Desert shrub - major plants include saltbush, greasewood, creosotebush, blackbrush, bursage, palo verde, mesquite, and cactus.

Poor Fair Good
Poor Fair Good
Poor Fair Good
Poor Fair Good
Poor Fair Good

80

87

93

71

81

89

62

74

85

66

74

79

48

57

63

30

41

48

75

85

89

58

73

80

41

61

71

67

80

85

51

63

70

35

47

55

63

77

85

88

55

72

81

86

49

68

79

84

1 Average runoff condition, and Ia = 0.2S. For range in humid regions, use table 2-2c.
2 Poor: <30% ground cover (litter, grass, and brush overstory). Fair: 30 to 70% ground cover. Good: > 70% ground cover.
3 Curve numbers for group A have been developed only for desert shrub.

2-8 A-1-18

(210-VI-TR-55, Second Ed., June 1986)

GaSWCC

Antecedent runoff condition
The index of runoff potential before a storm event is the antecedent runoff condition (ARC). ARC is an attempt to account for the variation in CN at a site from storm to storm. CN for the average ARC at a site is the median value as taken from sample rainfall and runoff data. The CN's in table 2-2 are for the average ARC, which is used primarily for design applications. See NEH-4 (SCS 1985) and Rallison and Miller (1981) for more detailed discussion of storm-to-storm variation and a demonstration of upper and lower enveloping curves.
Urban impervious area modifications
Several factors, such as the percentage of impervious area and the means of conveying runoff from impervious areas to the drainage system, should be considered in computing CN for urban areas (Rawls et al., 1981). For example, do the impervious areas connect directly to the drainage system, or do they outlet onto lawns or other pervious areas where infiltration can occur?
Connected impervious areas
An impervious area is considered connected if runoff from it flows directly into the drainage system. It is also considered connected if runoff from it occurs as concentrated shallow flow that runs over a pervious area and then into a drainage system.
Urban CN's (table 2-2a) were developed for typical land use relationships based on specific assumed percentages of impervious area. These CN values were developed on the assumptions that (a) pervious urban areas are equivalent to pasture in good hydrologic condition and (b) impervious areas have a CN of 98 and are directly connected to the drainage system. Some assumed percentages of impervious area are shown in table 2-2a.
If all of the impervious area is directly connected to the drainage system, but the impervious area percentages or the pervious land use assumptions in table 22a are not applicable, use figure 2-3 to compute a composite CN. For example, table 2-2a gives a CN of 70 for a 1/2-acre lot in HSG B, with an assumed impervious area of 25 percent. However, if the lot has 20 percent impervious area and a pervious area CN of 61, the composite CN obtained from figure 2-3 is 68. The CN difference between 70 and 68 reflects the difference in percent impervious area.

Unconnected impervious areas
Runoff from these areas is spread over a pervious area as sheet flow. To determine CN when all or part of the impervious area is not directly connected to the drainage system, (1) use figure 2-4 if total impervious area is less than 30 percent or (2) use figure 2-3 if the total impervious area is equal to or greater than 30 percent, because the absorptive capacity of the remaining pervious areas will not significantly affect runoff.
When impervious area is less than 30 percent, obtain the composite CN by entering the right half of figure 2-4 with the percentage of total impervious area and the ratio of total unconnected impervious area to total impervious area. Then move left to the appropriate pervious CN and read down to find the composite CN. For example, for a 1/2-acre lot with 20 percent total impervious area (75 percent of which is unconnected) and pervious CN of 61, the composite CN from figure 2-4 is 66. If all of the impervious area is connected, the resulting CN (from figure 2-3) would be 68.

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(210-VI-TR-55, Second Ed., June 1986)

2-9 A-1-19

Composite CN
(Unconnected impervious) (Total impervious)

100

Pervious CN = 90

90

80

80

70

60

70

50

40 60

50

40 0 10 20 30 40 50 60 70 80 90 100
Connected impervious area, %

Figure 2-3. - Composite CN with Connected Impervious Area

0.0

Pervious CN = 40

0.5

90 80 70 60 50

1.0

90

80 70

60 50

40 0

10

20 30

Composite CN

Total impervious area, %

Figure 2-4. - Composite CN with Unconnected Impervious Areas and Total Impervious Area Less Than 30%

2-10 A-1-20

(210-VI-TR-55, Second Ed., June 1986)

GaSWCC

Runoff
When CN and the amount of rainfall have been determined for the watershed, determine runoff by using figure 2-1, table 2-1, or equations 2-3 and 2-4. The runoff is usually rounded to the nearest hundredth of an inch.
Limitations
Curve numbers describe average conditions that are useful for design purposes. If the rainfall event used is a historical storm, the modeling accuracy decreases.
Use the runoff curve number equation with caution when recreating specific features of an actual storm. The equation does not contain an expression for time and, therefore, does not account for rainfall duration or intensity.
The user should understand the assumption reflected in the initial abstraction term (Ia) and should ascertain that the assumption applies to the situation. I , which consists of interception, initial infil-
a
tration, surface depression storage, evapotranspiration, and other factors, was generalized as 0.2S based on data from agricultural watersheds (S is the potential maximum retention after runoff begins). This approximation can be especially important in an urban application because the combination of impervious areas with pervious areas can imply a significant initial loss that may not take place. The opposite effect, a greater initial loss, can occur if the impervious areas have surface depressions that store some runoff. To use a relationship other than Ia = 0.2S, one must redevelop equation 2-3, figure 2-1, table 2-1, and table 2-2 by using the original rainfall-runoff data to establish new S or CN relationships for each cover and hydrologic soil group.
Runoff from snowmelt or rain on frozen ground cannot be estimated using these procedures.
The CN procedure is less accurate when runoff is less than 0.5 inch. As a check, use another procedure to determine runoff.
The SCS runoff procedures apply only to direct surface runoff: do not overlook large sources of subsurface flow or high ground water levels that contribute to runoff. These conditions are often related

to HSG A soils and forest areas that have been assigned relatively low CN's in table 2-2. Good judgment and experience based on stream gage records are needed to adjust CN's as conditions warrant.
When the weighted CN is less than 40, use another procedure to determine runoff.
Examples
Four examples illustrate the procedure for computing runoff curve number (CN) and runoff (Q) in inches. Worksheet 2 in appendix D is provided to assist TR-55 users. Figures 2-5 to 2-8 represent the use of worksheet 2 for each example. All four examples are based on the same watershed and the same storm event.
The watershed covers 250 acres in Dyer County, northwestern Tennessee. Seventy percent (175 acres) is a Loring soil, which is in hydrologic soil group C. Thirty percent (75 acres) is a Memphis soil, which is in group B. The event is a 25-year frequency, 24-hour storm with total rainfall of 6 inches.
Cover type and conditions in the watershed are different for each example. The examples, therefore, illustrate how to compute CN and Q for various situations of proposed, planned, or present development.
Example 2-1
The present cover type is pasture in good hydrologic condition. (See figure 2-5 for worksheet 2 information.)
Example 2-2
Seventy percent (175 acres) of the watershed, consisting of all the Memphis soil and 100 acres of the Loring soil, is 1/2-acre residential lots with lawns in good hydrologic condition. The rest of the watershed is scattered open space in good hydrologic condition. (See figure 2-6.)
Example 2-3
This example is the same as example 2-2, except that the 1/2-acre lots have a total impervious area of 35 percent. For these lots, the pervious area is lawns in good hydrologic condition. Since the impervious area percentage differs from the percentage assumed in table 2-2, use figure 2-3 to compute CN. (See figure 2-7.)

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(210-VI-TR-55, Second Ed., June 1986)

2-11 A-1-21

Example 2-4
This example is also based on example 2-2, except that 50 percent of the impervious area associated with the 1/2-acre lots on the Loring soil is "unconnected," that is, it is not directly connected to the drainage system. For these lots, the pervious area CN (lawn, good condition) is 74 and the impervious area is 25 percent. Use figure 2-4 to compute the CN for these lots. CN's for the 1/2-acre lots on Memphis soil and the open space on Loring soil are the same as those in example 2-2. (See figure 2-8.)

2-12 A-1-22

(210-VI-TR-55, Second Ed., June 1986)

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Figure 2-5. - Worksheet 2 for Example 2-1 (210-VI-TR-55, Second Ed., June 1986)

2-13 A-1-23

2-14 A-1-24

Figure 2-6. - Worksheet 2 for Example 2-2 (210-VI-TR-55, Second Ed., June 1986)

GaSWCC

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Figure 2-7. - Worksheet 2 for Example 2-3 (210-VI-TR-55, Second Ed., June 1986)

2-15 A-1-25

2-16 A-1-26

Figure 2-8. - Worksheet 2 for Example 2-4 (210-VI-TR-55, Second Ed., June 1986)

GaSWCC

Chapter 3: Time of concentration and travel time

Travel time (Tt) is the time it takes water to travel from one location to another in a watershed. Tt is a component of time of concentration (T ), which is the time for
c
runoff to travel from the hydraulically most distant point of the watershed to a point of interest within the watershed. Tc is computed by summing all the travel times for consecutive components of the drainage conveyance system.
Tc influences the shape and peak of the runoff hydrograph. Urbanization usually decreases T , thereby
c
increasing the peak discharge. But Tc can be increased as a result of (a) ponding behind small or inadequate drainage systems, including storm drain inlets and road culverts, or (b) reduction of land slope through grading.
Factors affecting time of concentration and travel time
Surface roughness
One of the most significant effects of urban development on flow velocity is less retardance to flow. That is, undeveloped areas with very slow and shallow overland flow through vegetation become modified by urban development: the flow is then delivered to streets, gutters, and storm sewers that transport runoff downstream more rapidly. Travel time through the watershed is generally decreased.
Channel shape and flow patterns
In small non-urban watersheds, much of the travel time results from overland flow in upstream areas. Typically, urbanization reduces overland flow lengths by conveying storm runoff into a channel as soon as possible. Since channel designs have efficient hydraulic characteristics, runoff flow velocity increases and travel time decreases.
Slope
Slopes may be increased or decreased by urbanization, depending on the extent of site grading or the extent to which storm sewers and street ditches are used in the design of the water management system. Slope will tend to increase when channels are straightened and decrease when overland flow is directed through storm sewers, street gutters, and diversions.

Computation of travel time and time of concentration

Water moves through a watershed as sheet flow, shallow concentrated flow, open channel flow, or some combination of these. The type that occurs is a function of the conveyance system and is best determined by field inspection.

Travel time (Tt) is the ratio of flow length to flow velocity:

Tt =

L

3600 V

[Eq. 3-1]

where

T = travel time (hr), t
L = flow length (ft),
V = average velocity (ft/s), and
3600 = conversion factor from seconds to hours.

Time of concentration (Tc) is the sum of Tt values for the various consecutive flow segments:

where

T = T + T +... T

c

t1

t2

tm

[Eq. 3-2]

Tc = time of concentration (hr) and m = number of flow segments.

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(210-VI-TR-55, Second Ed., June 1986)

3-1 A-1-27

.50

.20

Watercourse slope, ft/ft
Unpaved Paved

.10 .06 .04
.02

.01

.005 1

2

4

6

10

20

Average velocity, ft/sec

Figure 3-1. - Average Velocities for Estimating Travel Time for Shallow Concentrated Flow

3-2 A-1-28

(210-VI-TR-55, Second Ed., June 1986)

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Sheet flow

Sheet flow is flow over plane surfaces. It usually occurs in the headwater of streams. With sheet flow, the friction value (Manning's n) is an effective roughness coefficient that includes the effect of raindrop impact; drag over the plane surface; obstacles such as litter, crop ridges, and rocks; and erosion and transportation of sediment. These n values are for very shallow flow depths of about 0.1 foot or so. Table 3-1 gives Manning's n values for sheet flow for various surface conditions.

For sheet flow of less than 300 feet, use Manning's kinematic solution (Overton and Meadows 1976) to compute Tt:

Tt = 0.007 (nL)0.8 (P2)0.5 s0.4

[Eq. 3-3]

where
Tt = travel time (hr), n = Manning's roughness coefficient (table 3-1),
L = flow length (ft),
P2 = 2-year, 24-hour rainfall (in), and s = slope of hydraulic grade line (land slope, ft/ft).

Table 3-1. - Roughness Coefficients (Manning's n) for Sheet Flow

Surface description

n1

Smooth surfaces (concrete, asphalt, gravel, or bare soil) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.011
Fallow (no residue) . . . . . . . . . . . . . . . . . . . . . 0.05
Cultivated soils: Residue cover >20% . . . . . . . . . . . . . . . . . . . 0.06 Residue cover >20% . . . . . . . . . . . . . . . . . . . 0.17
Grass: Short grass prairie . . . . . . . . . . . . . . . . . . . . . 0.15 Dense grasses2 . . . . . . . . . . . . . . . . . . . . . . . 0.24 Bermudagrass . . . . . . . . . . . . . . . . . . . . . . . . 0.41
Range (natural) . . . . . . . . . . . . . . . . . . . . . . . . 0.13
Woods:3 Light underbrush . . . . . . . . . . . . . . . . . . . . . . 0.40 Dense underbrush . . . . . . . . . . . . . . . . . . . . 0.80

This simplified form of the Manning's kinematic solution is based on the following: (1) shallow steady uniform flow, (2) constant intensity of rainfall excess (that part of a rain available for runoff), (3) rainfall duration of 24 hours, and (4) minor effect of infiltration on travel time. Rainfall depth can be obtained from appendix B.

1 The n values are a composite of information compiled by Engman (1986). 2 Includes species such as weeping lovegrass, bluegrass, buffalo grass, blue grama grass, and native grass mixtures. 3 When selecting n, consider cover to a height of about 0.1 ft. This is the only part of the plant cover that will obstruct sheet flow.

Shallow concentrated flow
After a maximum of 300 feet, sheet flow usually becomes shallow concentrated flow. The average velocity for this flow can be determined from figure 3-1, in which average velocity is a function of watercourse slope and type of channel. For slopes less than 0.005 ft/ft, use equations given in appendix F for figure 3-1. Tillage can affect the direction of shallow concentrated flow. Flow may not always be directly down the watershed slope if tillage runs across the slope.
After determining average velocity in figure 3-1, use equation 3-1 to estimate travel time for the shallow concentrated flow segment.
Open channels
Open channels are assumed to begin where surveyed cross section information has been obtained, where channels are visible on aerial photographs, or where blue lines (indicating streams) appear on United States Geological Survey (USGS) quadrangle sheets. Manning's equation or water surface profile information

can be used to estimate average flow velocity. Average flow velocity is usually determined for bank-full elevation.

Manning's equation is

V =1.49 r2/3 s1/2 n

[Eq. 3-4]

where

V = average velocity (ft/s), r = hydraulic radius (ft) and is equal to a/pw, a = cross sectional flow area (ft2), pw = wetted perimeter (ft), s = slope of the hydraulic grade line (channel
slope, ft/ft), and n = Manning's roughness coefficient for open
channel flow.

Manning's n values for open channel flow can be ob-
tained from standard textbooks such as Chow (1959)
or Linsley et al. (1982). After average velocity is com-
puted using equation 3-4, Tt for the channel segment can be estimated using equation 3-1.

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(210-VI-TR-55, Second Ed., June 1986)

3-3 A-1-29

Reservoirs or lakes
Sometimes it is necessary to estimate the velocity of flow through a reservoir or lake at the outlet of a watershed. This travel time is normally very small and can be assumed as zero.
Limitations
Manning's kinematic solution should not be used for sheet flow longer than 300 feet. Equation 3-3 was developed for use with the four standard rainfall intensity-duration relationships.
In watersheds with storm sewers, carefully identify the appropriate hydraulic flow path to estimate Tc. Storm sewers generally handle only a small portion of a large event. The rest of the peak flow travels by streets, lawns, and so on, to the outlet. Consult a standard hydraulics textbook to determine average velocity in pipes for either pressure or nonpressure flow.
The minimum Tc used in TR-55 is 0.1 hour.
A culvert or bridge can act as a reservoir outlet if there is significant storage behind it. The procedures in TR-55 can be used to determine the peak flow upstream of the culvert. Detailed storage routing procedures should be used to determine the outflow through the culvert.

Example 3-1
The sketch below shows a watershed in Dyer County, northwestern Tennessee. The problem is to compute Tc at the outlet of the watershed (point D). The 2-year 24hour rainfall depth is 3.6 inches. All three types of flow occur from the hydraulically most distant point (A) to the point of interest (D). To compute Tc, first determine Tt for each segment from the following information:
Segment AB: Sheet flow; dense grass; slope (s) = 0.01 ft/ft; and length (L) = 100 ft.
Segment BC: Shallow concentrated flow; unpaved; s = 0.01 ft/ft; and L = 1400 ft.
Segment CD: Channel flow; Manning's n =.05; flow area (a) = 27 ft2; wetted perimeter (pw) = 28.2 ft: s = 0.005 ft/ft; and L = 7300 ft.
See figure 3-2 for the computations made on worksheet 3.

100 ft

1,400 ft

7,300 ft

A

B

C

D

(not to scale)

3-4 A-1-30

(210-VI-TR-55, Second Ed., June 1986)

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Figure 3-2. - Worksheet 3 for Example 3-1 (210-VI-TR-55, Second Ed., June 1986)

3-5 A-1-31

A-1-32

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Chapter 4: Graphical Peak Discharge method

This chapter presents the Graphical Peak Discharge method for computing peak discharge from rural and urban areas. The Graphical method was developed from hydrograph analyses using TR-20, "Computer Program for Project Formulation - Hydrology" (SCS 1983). The peak discharge equation used is

where

q = q A QF

p

um p

[Eq. 4-1]

qp = peak discharge (cfs); qu = unit peak discharge (csm/in); Am = drainage area (mi2); Q = runoff (in); and F = pond and swamp adjustment factor.
p
The input requirements for the Graphical method are as follows: (1) T (hr), (2) drainage area (mi2), (3) appro-
c
priate rainfall distribution (I, IA, II, or III), (4) 24-hour rainfall (in), and (5) CN. If pond and swamp areas are spread throughout the watershed and are not considered in the Tc computation, an adjustment for pond and swamp areas is also needed.

Peak discharge computation

For a selected rainfall frequency, the 24-hour rainfall (P) is obtained from appendix B or more detailed local precipitation maps. CN and total runoff (Q) for the watershed are computed according to the methods outlined in chapter 2. The CN is used to determine the initial abstraction (Ia) from table 4-1. Ia/P is then computed.
If the computed Ia/P ratio is outside the range shown in exhibit 4 (4-I, 4-IA, 4-II, and 4-III) for the rainfall distribution of interest, then the limiting value should be used. If the ratio falls between the limiting values, use linear interpolation. Figure 4-1 illustrates the sensitivity of I /P
a
to CN and P.

Peak discharge per square mile per inch of runoff
(qu) is obtained from exhibit 4-I, 4-IA, 4-II, or 4-III by using Tc (chapter 3), rainfall distribution type, and Ia/P ratio. The pond and swamp adjustment factor is obtained
from table 4-2 (rounded to the nearest table value). Use
worksheet 4 in appendix D to aid in computing the peak
discharge using the Graphical method.

1.0

.8

.6

Ia/P

CN=40
.4 50
60 70 .2 80 90

0

1

3

5

7

9

11

13

15

Rainfall (P), inches

Figure 4-1. - Variation of Ia/P for P and CN

Table 4-1. - I Values for Runoff Curve Numbers a

Curve number
40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69

I a
(in)
3.000 2.878 2.762 2.651 2.545 2.444 2.348 2.255 2.167 2.082 2.000 1.922 1.846 1.774 1.704 1.636 1.571 1.509 1.448 1.390 1.333 1.279 1.226 1.175 1.125 1.077 1.030 0.985 0.941 0.899

Curve number
70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98

I a
(in)
0.857 0.817 0.778 0.740 0.703 0.667 0.632 0.597 0.564 0.532 0.500 0.469 0.439 0.410 0.381 0.353 0.326 0.299 0.273 0.247 0.222 0.198 0.174 0.151 0.128 0.105 0.083 0.062 0.041

GaSWCC

(210-VI-TR-55, Second Ed., June 1986)

4-1 A-1-33

Table 4-2. - Adjustment Factor (Fp) for Pond and Swamp Areas that are Spread throughout the Watershed

Percentage of pond and swamp areas Fp

0

1.00

0.2

0.97

1.0

0.87

3.0

0.75

5.0

0.72

Example 4-1
Compute the 25-year peak discharge for the 250acre watershed described in examples 2-2 and 3-1. Figure 4-2 shows how worksheet 4 is used to compute qp as 345 cfs.

Limitations

The Graphical method provides a determination of peak discharge only. If a hydrograph is needed or watershed subdivision is required, use the Tabular Hydrograph method (chapter 5). Use TR-20 if the watershed is very complex or a higher degree of accuracy is required.

The watershed must be hydrologically homogeneous, that is, describable by one CN. Land use, soils, and cover are distributed uniformly throughout the watershed.

The watershed may have only one main stream or, if more than one, the branches must have nearly equal T 's.
c
The method cannot perform valley or reservoir routing.



The F factor can be applied only for ponds or p

swamps that are not in the Tc flow path.

Accuracy of peak discharge estimated by this method will be reduced if Ia/P values are used that are outside the range given in exhibit 4. The limit-
ing Ia/P values are recommended for use.

This method should be used only if the weighted CN is greater than 40.

When this method is used to develop estimates of peak discharge for both present and developed conditions of a watershed, use the same procedure for estimating Tc.



T values with this method may range from 0.1 to c

10 hours.

4-2 A-1-34

(210-VI-TR-55, Second Ed., June 1986)

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GaSWCC

Figure 4-2. - Worksheet 4 for Example 4-1 (210-VI-TR-55, Second Ed., June 1986)

4-3 A-1-35

4-4 A-1-36

500 300 200 100
80 60 40
.1

Ia /P = 0.10 0.20 0.25 0.30 0.35 0.40

Unit peak discharge (qu), csm/in

Exhibit 4-I: Unit Peak Discharge (qu) for SCS Type I Rainfall Distribution (210-VI-TR-55, Second Ed., June 1986)

GaSWCC

0.45 0.50

.2

.4

.6 .8 1

2

4

6

8 10

Time of concentration (Tc), hours

200 100
80 60 40 30
.1

Ia/P = 0.10 0.20 0.25 0.30 0.50

Unit peak discharge (qu), csm/in

GaSWCC

Exhibit 4-IA: Unit Peak Discharge (qu) for SCS Type IA Rainfall Distribution (210-VI-TR-55, Second Ed., June 1986)

.2

.4

.6 .8 1

2

4

6 8 10

Time of concentration (Tc), hours

4-5 A-1-37

4-6 A-1-38

1000 800 600 500 400 300 200

Ia/P = 0.10 0.30
0.35
0.40 0.45 0.50

Unit peak discharge (qu), csm/in

Exhibit 4-II: Unit Peak Discharge (qu) for SCS Type II Rainfall Distribution (210-VI-TR-55, Second Ed., June 1986)

GaSWCC

100 80

60

50

.1

.2

.4

.6 .8 1

2

4

6 8 10

Time of concentration (Tc), inches

700

600 500

Ia/P = 0.10

400

0.30 0.35

0.40

300

0.45

0.50 200

Unit peak discharge (qu), csm/in

GaSWCC

Exhibit 4-III: Unit Peak Discharge (qu) for SCS Type III Rainfall Distribution (210-VI-TR-55, Second Ed., June 1986)

100 80

60

40

.1

.2

.4

.6 .8 1

2

4

6 8 10

Time of connection (Tc), hours

4-7 A-1-39

A-1-40

GaSWCC

Chapter 5: Tabular Hydrograph method

This chapter presents the Tabular Hydrograph method of computing peak discharges from rural and urban areas, using time of concentration (T ) and travel
c
time (Tt) from a subarea as inputs. This method approximates TR-20, a more detailed hydrograph procedure (SCS 1983).
The Tabular method can develop partial composite flood hydrographs at any point in a watershed by dividing the watershed into homogeneous subareas. In this manner, the method can estimate runoff from nonhomogeneous watersheds. The method is especially applicable for estimating the effects of land use change in a portion of a watershed. It can also be used to estimate the effects of proposed structures.
Input data needed to develop a partial composite flood hydrograph include (1) 24-hour rainfall (in), (2) appropriate rainfall distribution (I, IA, II, or III), (3) CN, (4) T
c
(hr), (5) Tt (hr), and (6) drainage area (mi2).
Tabular Hydrograph method exhibits
Exhibit 5 (5-I, 5-IA, 5-II, and 5-III) shows tabular discharge values for the various rainfall distributions. Tabular discharges expressed in csm/in (cubic feet of discharge per second per square mile of watershed per inch of runoff) are given for a range of subarea Tc's from 0.1 to 2 hours and reach Tt's from 0 to 3 hours.
The exhibit was developed by computing hydrographs for 1 square mile of drainage area for selected Tc's and routing them through stream reaches with the range of T 's indicated. The Modified Att-Kin method for reach
t
routing, formulated by SCS in the late 1970's, was used to compute the tabular hydrographs (Comer et al., 1981). A CN of 75 and rainfall amounts generating appropriate Ia/P ratios were used. The resulting runoff estimate was used to convert the hydrographs in exhibits 5-I through 5-III to cubic feet per second per square mile per inch of runoff.
An assumption in development of the tabular hydrographs is that all discharges for a stream reach flow at the same velocity. By this assumption, the subarea flood hydrographs may be routed separately and added at the reference point. The tabular hydrographs in exhibit 5 are prerouted hydrographs. For Tt's other than zero, the tabular discharge values represent the contribution from a single subarea to the composite hydrograph at Tt downstream.

Information required for Tabular
Hydrograph method
The following information is required for the Tabular method:
1. Subdivision of the watershed into areas that are relatively homogeneous and have convenient routing reaches.
2. Drainage area of each subarea in square miles.
3. Tc for each subarea in hours. The procedure for estimating T is outlined in chapter 3.
c
Worksheet 3 (appendix D) can be used to calculate Tc. 4. T for each routing reach in hours. The proce-
t
dure for estimating Tt is outlined in chapter 3. Worksheet 3 can be used to calculate Tt through a subarea for shallow concentrated and open channel flow. 5. Weighted CN for each subarea. Table 2-2 shows CN's for individual hydrologic soil cover combinations. Worksheet 2 can be used to calculate the weighted runoff curve number. 6. Appropriate rainfall distribution according to figure B-2 (appendix B). 7. The 24-hour rainfall for the selected frequency. Appendix B contains rainfall maps for various frequencies (figures B-3 to B-8). 8. Total runoff (Q) in inches computed from CN and rainfall. 9. Ia for each subarea from table 5-1, which is the same as table 4-1. 10. Ratio of I /P for each subarea. If the ratio for
a
the rainfall distribution of interest is outside the range shown in exhibit 5, use the limiting value.

GaSWCC

(210-VI-TR-55, Second Ed., June 1986)

5-1 A-1-41

Development of composite flood hydrograph

This section describes the procedure for developing the peak discharge and selected discharge values of a composite flood hydrograph.

Selecting Tc and Tt
First, use worksheet 5a to develop a summary of basic watershed data by subarea. Then use worksheet 5b to develop a tabular hydrograph discharge summary; this summary displays the effect of individual subarea hydrographs as routed to the watershed point of interest. Use Tt for each subarea as the total reach travel time from that subarea through the watershed to the point of interest. Compute the hydrograph coordinates for selected Tt's using the appropriate sheets in exhibit 5. The flow at any time is

q = qtAmQ

[Eq. 5-1]

Tc T
t
Sum

Actual values
1.1 1.7 2.8

Table values by rounding method-

1

2

3

1.0

1.0

1.25

1.5

2.0

1.5

2.5

3.0

2.75

In this instance, the results from method 3 would be selected because the sum 2.75 is closest to the actual sum of 2.8.
Selecting Ia/P
The computed I /P value can be rounded to the neara
est Ia/P value in exhibits 5-I through 5-III, or the hydrograph values (csm/in) can be linearly interpolated because Ia/P interpolation generally involves peaks that occur at the same time.

where

q = hydrograph coordinate (cfs) at hydrograph
time t;
qt = tabular hydrograph unit discharge from exhibit 5 (csm/in);
Am = drainage area of individual subarea (mi2); and
Q = runoff (in).

Since the timing of peak discharge changes with T c
and Tt, interpolation of peak discharge for Tc and Tt values for use in exhibit 5 is not recommended. Interpola-

tion may result in an estimate of peak discharge that

would be invalid because it would be lower than either

of the hydrographs. Therefore, round the actual values

of Tc and Tt to values presented in exhibit 5. Perform this rounding so that the sum of the selected table val-

ues is close to the sum of actual T and T . An accept-

c

t

able procedure is to select the results of one of three

rounding operations:

1. Round Tc and Tt separately to the nearest table value and sum;

2. Round Tc down and Tt up to nearest table value and sum; and

3. Round T up and T down to nearest table

c

t

value and sum.

From these three alternatives, choose the pair of

rounded Tc and Tt values whose sum is closest to the

sum of the actual T and T . If two rounding methods

c

t

produce sums equally close to the actual sum, use the

combination in which rounded Tc is closest to actual Tc. An illustration of the rounding procedure is as follows:

Table 5-1. - I Values for Runoff Curve Numbers a

Curve number
40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69

Ia (in)
3.000 2.878 2.762 2.651 2.545 2.444 2.348 2.255 2.167 2.082 2.000 1.922 1.846 1.774 1.704 1.636 1.571 1.509 1.448 1.390 1.333 1.279 1.226 1.175 1.125 1.077 1.030 0.985 0.941 0.899

Curve number
70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98

Ia (in)
0.857 0.817 0.778 0.740 0.703 0.667 0.632 0.597 0.564 0.532 0.500 0.469 0.439 0.410 0.381 0.353 0.326 0.299 0.273 0.247 0.222 0.198 0.174 0.151 0.128 0.105 0.083 0.062 0.041

5-2 A-1-42

(210-VI-TR-55, Second Ed., June 1986)

GaSWCC

Summing for the composite hydrograph

Examples

The composite hydrograph is the summation of prerouted individual subarea hydrographs at each time shown on worksheet 5b. Only the times encompassing the expected maximum composite discharge are summed to define a portion of the composite hydrograph.

If desired, the entire composite hydrograph can be approximated by linear extrapolation as follows:

1. Set up a table similar to worksheet 5b. Include on this table the full range of hydrograph times displayed in exhibit 5.
2. Compute the subarea discharge values for those times and insert them in the table.
3. Sum the values to obtain the composite hydrograph.
4. Apply linear extrapolation to the first two points and the last two points of the composite hydrograph. The volume under this approximation of the entire composite hydrograph may differ from the computed runoff volume.

Limitations

The Tabular method is used to determine peak flows and hydrographs within a watershed. However, its accuracy decreases as the complexity of the watershed increases. If you want to compare present and developed conditions of a watershed, use the same procedure for estimating Tc for both conditions.
Use the TR-20 computer program (SCS 1983) instead of the Tabular method if any of the following conditions applies:

Tt is greater than 3 hours (largest Tt in exhibit 5).



T is greater than 2 hours (largest T in exhibit 5).

c

c

Drainage areas of individual subareas differ by a factor of 5 or more.

A developer proposes to put a subdivision, Fallswood, in subareas 5, 6, and 7 of a watershed in Dyer County, northwestern Tennessee (see sketch below). Before approving the developer's proposal, the planning board wants to know how the development would affect the 25-year peak discharge at the downstream end of subarea 7. The rainfall distribution is type II (figure B-2), and the 24-hour rainfall (P) is 6.0 inches (figure B-6).
Example 5-1
Compute the 25-year frequency peak discharge at the downstream end of subarea 7 for present conditions, using worksheets 5a and 5b. To do this, first calculate the present condition CN, Tc, and Tt for each subarea, using the procedures in chapters 2 and 3. Enter the values on worksheet 5a (figure 5-1).
Next, compute the prerouted hydrograph points for each subarea hydrograph over a range of time near the peak discharge using worksheet 5b (figure 5-2) and the appropriate exhibit 5. For example, for subarea 4, in which Tc = 0.75 hr, refer to sheet 6 of exhibit 5-II. With Tt of 2.00 hr (the sum of downstream travel time through subareas 5 and 7 to the outlet) and Ia/P of 0.1, the routed peak discharge of subarea 4 at the outlet of subarea 7 occurs at 14.6 hr and is 274 csm/in. Solving equation 51 with appropriate values provides the peak discharge (q) for subarea 4 at 14.6 hr:
q = qt(AmQ) = (274)(0.70) = 192 cfs.
Once all the prerouted subarea hydrographs have been tabulated on worksheet 5b, sum each of the time columns to obtain the composite hydrograph. The resulting 25-year frequency peak discharge is 720 cfs at 14.3 hr (figure 5-2).

2

1

The entire composite flood hydrograph or entire

runoff volume is required for detailed flood routings.

The hydrograph based on extrapolation is only an

4

approximation of the entire hydrograph.

3

1 Subarea

The time of peak discharge must be more accurate than that obtained through the Tabular method.
The composite flood hydrograph should be compared with actual stream gage data where possible. The instantaneous peak flow value from the composite flood hydrograph can be compared with data from USGS curves of peak flow versus drainage area.

6 5
7

Stream
Watershed boundary Subarea boundary

GaSWCC

(210-VI-TR-55, Second Ed., June 1986)

5-3 A-1-43

Example 5-2
Compute the 25-year frequency peak discharge at the downstream end of subarea 7 for the developed conditions, using worksheets 5a and 5b.
First, calculate the developed condition CN, Tc, and T for each subarea, using the procedures in chapters 2
t
and 3. Enter the values on worksheet 5a (figure 5-3).
Next, compute the prerouted hydrograph points for each subarea hydrograph over a range of time near the peak discharge using worksheet 5b (figure 5-4) and the appropriate exhibit 5. For example, for subarea 6, in which Tc = 1.0 hr, refer to sheet 7 of exhibit 5-II. With Tt of 0.5 hr (downstream travel time through subarea 7 to the outlet) and Ia/P of 0.1, the peak discharge of subarea 6 at the outlet of the watershed occurs at 13.2 hr and is 311 csm/in. Solving equation 5-1 provides the peak discharge (q):
q = qt(AmQ) = (311)(1.31) = 407 cfs.
Once all the prerouted subarea hydrographs have been tabulated on worksheet 5b, sum each of the time columns to obtain the composite hydrograph. The resulting 25-year frequency peak discharge is 872 cfs at 13.6 hr (figure 5-4).
Comparison
According to the results of the two examples, the proposed subdivision at the downstream end of subarea 7 is expected to increase peak discharge from 720 to 872 cfs and to decrease the time to peak from 14.3 to 13.6 hr.

5-4 A-1-44

(210-VI-TR-55, Second Ed., June 1986)

GaSWCC

GaSWCC

Figure 5-1. - Worksheet 5a for Example 5-1 (210-VI-TR-55, Second Ed., June 1986)

5-5 A-1-45

5-6 A-1-46

Figure 5-2. - Worksheet 5b for Example 5-1 (210-VI-TR-55, Second Ed., June 1986)

GaSWCC

GaSWCC

Figure 5-3. - Worksheet 5a for Example 5-2 (210-VI-TR-55, Second Ed., June 1986)

5-7 A-1-47

5-8 A-1-48

Figure 5-4. - Worksheet 5b for Example 5-2 (210-VI-TR-55, Second Ed., June 1986)

GaSWCC

GaSWCC

Exhibit 5-I: Tabular hydrograph unit discharges (csm/in) for type I rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

9.3

9.9

10.1

10.3

10.5

10.7

11.0

11.4

11.8

12.3

13.0

14.0

15.0

16.0

18.0

24.0

(HR) 9.0

9.6

10.0

10.2

10.4

10.6

10.8

11.2

11.6

12.0

12.6

13.5

14.5

15.5

17.0

20.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.1 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 30 40 56 183 337 504 326 155 122 107 93 81 73 66 60 56 54 52 49 46 44 40 36 32 30 29 28 27 26 24 20 13

.10 26 35 48 93 153 276 428 360 223 156 123 103 88 72 65 59 56 54 51 47 45 42 37 33 30 29 28 28 26 24 21 13

.20 23 30 41 60 82 129 227 361 360 269 194 147 118 85 71 63 58 55 53 49 46 43 39 35 31 29 29 28 26 24 21 14

.30 22 29 39 56 73 111 188 303 341 293 227 173 136 94 75 65 60 56 54 50 47 43 39 35 31 29 29 28 26 25 21 14

.40 18 25 34 46 .50 18 24 32 44 .75 14 19 25 34 1.0 11 14 19 26

53 66 96 157 255 312 300 251 199 126 90 73 64 59 56 52 48 44 40 36 32 30 29 28 26 25 50 61 84 133 214 280 293 265 221 144 99 77 66 60 56 52 49 45 41 37 32 30 29 28 27 25 38 43 49 62 88 134 190 234 252 221 162 115 87 71 63 56 52 47 43 39 35 31 29 29 27 25 28 31 34 38 44 52 68 98 141 222 238 191 139 101 79 63 56 51 45 41 37 33 30 29 27 26

21 14 21 14 22 15 22 15

1.5 9 10 13 17 18 20 22 25 27 30 34 38 44 74 132 191 211 190 151 101 73 58 50 45 41 37 33 30 28 27 23 16

2.0 6 7 9 11 12 13 14 15 16 18 20 22 24 29 38 58 97 148 193 193 141 89 61 51 46 41 37 33 29 27 24 17

2.5 4 5 7 8 9 9 10 11 11 12 13 14 16 19 23 29 39 58 93 154 181 147 87 61 51 45 41 37 30 28 25 18

3.0 2 3 5 6 6 7 7 8 9 9 10 10 11 13 15 19 23 28 39 72 124 170 138 86 61 50 45 40 33 29 26 19

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.1 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 61 195 343 232 129 113 103 91 81 76 71 66 64 62 61 59 56 54 51 47 43 40 40 39 39 37 36 31 21

.10 0 0 0 12 45 145 277 247 169 131 112 98 87 76 70 65 64 62 60 57 55 53 49 44 40 40 39 39 38 36 32 21

.20 0 0 0 9 33 107 220 238 192 151 125 107 94 79 71 66 64 62 61 58 56 53 49 45 41 40 40 39 38 36 32 21

.30 0 0 0 1 6 24 79 173 216 200 168 139 113 90 77 70 66 64 62 59 57 54 50 46 41 40 40 39 38 36 32 22

.40 0 0 0 1 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

4 17 59 135 189 196 177 152 129 97 81 72 67 64 63 60 57 54 51 46 42 40 40 39 38 36 0 3 12 43 104 161 185 180 161 121 93 79 71 66 64 61 53 55 52 48 43 40 40 39 38 37 0 1 5 18 49 92 130 153 159 142 114 92 79 71 66 63 60 56 53 49 44 41 40 40 33 37 0 0 0 0 2 9 27 56 92 144 152 128 103 86 75 67 63 59 55 51 47 43 40 40 39 37

32 22 33 22 33 23 34 24

1.5 0 0 0 0 0 0 0 0 0 0 0 2 6 32 79 121 136 127 109 85 72 64 58 55 51 47 43 40 39 38 34 25

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 9 33 70 105 126 118 97 75 63 58 54 50 46 42 40 39 35 26

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 11 32 63 105 118 100 75 63 58 54 50 46 40 39 36 27

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 12 43 84 112 96 74 63 58 54 50 42 40 37 28

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.1 HR * * *

IA/P =0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 3 13 28 39 44 45 46 46 48 49 51 53 54 54 55 56 55 53 50 50 49 49 49 49 48 45 32

.10 0 0 0 0 0 2 9 22 33 41 44 45 46 48 49 50 52 54 54 54 56 55 53 50 50 49 49 49 49 48 45 32

.20 0 0 0 0 0 0 1 7 17 28 36 41 44 46 48 49 51 53 54 54 56 56 54 51 50 50 49 49 49 48 45 32

.30 0 0 0 0 0 0 0 1 5 13 23 32 38 44 47 48 50 51 53 54 54 55 54 52 50 50 49 49 49 48 46 33

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 3 10 18 27 34 43 46 48 49 51 53 54 54 55 54 52 50 50 49 49 49 48 46 33 0 0 0 0 0 2 7 15 23 36 43 46 48 50 51 53 54 55 55 53 50 50 49 49 49 48 46 34 0 0 0 0 0 1 3 7 13 27 37 43 46 48 50 52 54 55 55 54 51 50 50 49 49 48 46 34 0 0 0 0 0 0 0 0 1 8 20 32 40 45 47 50 52 54 55 54 52 50 50 49 49 49 47 36

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 13 23 33 42 47 51 54 55 54 53 50 50 49 49 48 37

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 12 25 37 46 51 54 55 54 52 50 49 49 48 39

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 15 31 45 51 53 55 54 52 50 49 48 41

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 14 32 45 51 53 54 54 51 49 48 42

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = I

* * * TC = 0.1 HR * * *

SHEET 1 OF 10

5-9 A-1-49

5-10 A-1-50

Exhibit 5-I, continued: Tabular hydrograph unit discharges (csm/in) for type I rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

9.3

9.9

10.1

10.3

10.5

10.7

11.0

11.4

11.8

12.3

13.0

14.0

15.0

16.0

18.0

24.0

(HR) 9.0

9.6

10.0

10.2

10.4

10.6

10.8

11.2

11.6

12.0

12.6

13.5

14.5

15.5

17.0

20.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.2 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 28 37 52 126 220 379 405 267 168 129 108 92 80 69 62 58 55 53 50 47 44 41 37 33 30 29 28 27 26 24 21 13

.10 24 32 44 71 108 182 313 375 303 213 157 124 103 78 68 61 57 55 52 49 46 42 38 34 30 29 29 28 26 24 21 14

.20 21 28 38 53 65 94 153 260 336 314 247 187 145 97 77 67 60 57 54 50 47 44 39 35 31 30 29 28 26 25 21 14

.30 20 27 36 50 60 82 129 216 296 308 267 214 168 110 82 69 62 58 55 51 47 44 40 36 32 30 29 28 26 25 21 14

.40 17 23 31 42 .50 16 22 30 40 .75 13 17 24 32 1.0 11 13 17 24

47 56 74 111 181 258 291 275 234 152 103 79 68 61 57 53 49 45 41 37 33 30 29 28 27 25 45 52 66 96 153 223 269 273 247 171 115 86 71 63 58 54 50 46 42 37 33 30 29 28 27 25 35 39 44 52 68 99 145 194 229 240 183 132 97 77 66 58 53 48 44 39 35 31 30 29 27 26 26 29 32 35 39 45 56 75 107 189 229 206 158 115 88 67 58 52 46 42 38 34 31 29 28 26

22 14 22 14 22 15 23 15

1.5 8 10 12 15 17 19 21 23 25 28 31 35 39 60 106 166 204 197 165 112 79 60 51 46 42 37 33 30 28 27 23 16

2.0 5 7 9 10 11 12 13 14 15 17 18 20 22 27 34 49 79 126 169 188 152 97 64 52 46 42 38 34 29 28 24 17

2.5 3 5 6 8 8 9 10 10 11 12 13 14 15 18 22 26 34 49 77 136 176 155 95 64 52 46 42 37 31 28 25 18

3.0 2 3 4 5 6 6 7 7 8 8 9 9 10 11 13 16 19 23 29 49 91 154 167 102 67 53 47 42 34 29 26 19

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.2 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 22 76 206 258 207 144 119 104 92 82 74 68 65 63 62 60 57 55 52 48 44 40 40 39 39 38 36 32 21

.10 0 0 0 3 16 56 156 224 213 167 135 114 99 81 73 67 65 63 61 58 56 53 50 45 41 40 40 39 38 36 32 22

.20 0 0 0 2 11 41 118 189 205 179 150 126 108 85 75 69 65 63 62 59 56 54 50 46 41 40 40 39 38 36 32 22

.30 0 0 0 0 2 8 30 88 155 188 182 161 138 103 83 74 68 65 63 60 57 55 51 47 42 40 40 39 38 36 32 22

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

1 6 22 66 126 167 177 166 147 111 88 76 69 66 63 61 58 55 51 47 43 40 40 39 38 37 33 22 0 1 4 16 50 100 145 167 166 136 105 35 75 69 65 62 59 56 53 49 44 41 40 40 38 37 33 23 0 0 2 7 22 50 87 119 140 148 124 101 85 74 69 64 61 57 54 50 45 42 40 40 38 37 33 23 0 0 0 0 1 3 11 28 55 114 142 135 113 93 80 69 64 60 56 52 48 44 41 40 39 37 34 24

1.5 0 0 0 0 0 0 0 0 0 0 0 1 2 17 52 97 124 129 115 91 75 65 59 55 52 48 43 41 39 38 35 25

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 19 49 84 111 120 102 79 65 59 55 51 47 43 40 39 36 26

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 6 20 45 89 113 104 78 65 59 55 51 47 41 39 36 28

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 7 30 68 108 99 77 65 58 54 50 43 40 37 29

IA/P = 0.50

* * * TC = 0.2 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 4 15 28 38 43 45 45 48 49 50 52 53 53 53 53 53 53 50 50 50 49 49 49 48 45 32

.10 0 0 0 0 0 0 3 11 22 32 40 43 45 47 48 50 52 53 53 53 53 53 53 50 50 50 49 49 49 48 45 32

.20 0 0 0 0 0 0 2 8 17 27 36 41 43 46 48 49 51 53 53 53 53 53 53 51 50 50 49 49 49 48 45 33

.30 0 0 0 0 0 0 1 6 13 23 31 38 41 45 48 49 51 52 53 53 53 53 53 51 50 50 49 49 49 48 46 33

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 1 4 10 19 27 34 39 44 47 49 50 52 53 53 53 53 53 51 50 50 49 49 49 48 46 33 0 0 1 3 8 15 23 30 36 43 46 48 50 51 53 53 53 53 53 52 50 50 49 49 49 48 46 33 0 0 0 0 3 8 14 20 27 37 43 46 48 50 52 53 53 53 53 52 50 50 50 49 49 48 46 34 0 0 0 0 0 0 0 2 4 14 26 36 42 46 48 51 52 53 53 53 52 50 50 49 49 49 47 35

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 13 23 33 40 46 49 52 53 53 53 51 50 50 49 49 48 37

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 8 16 26 37 44 50 52 53 53 53 51 50 49 49 48 38

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 8 19 31 43 50 52 53 53 52 51 50 49 48 39

3.0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 3 11 25 41 49 52 53 53 52 50 49 48 41

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = I

* * * TC = 0.2 HR * * *

SHEET 2 OF 10

GaSWCC

GaSWCC

Exhibit 5-I, continued: Tabular hydrograph unit discharges (csm/in) for type I rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

9.3

9.9

10.1

10.3

10.5

10.7

11.0

11.4

11.8

12.3

13.0

14.0

15.0

16.0

18.0

24.0

(HR) 9.0

9.6

10.0

10.2

10.4

10.6

10.8

11.2

11.6

12.0

12.6

13.5

14.5

15.5

17.0

20.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.3 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 25 34 46 87 138 242 349 346 256 182 141 115 97 76 66 60 57 54 52 48 45 42 38 34 30 29 28 28 26 24 21 13

.10 24 32 44 77 118 200 299 330 281 215 166 132 109 82 69 62 58 55 52 49 46 42 38 34 30 29 29 23 26 24 21 14

.20 21 28 38 54 69 102 167 255 305 289 240 190 152 103 79 67 61 57 54 50 47 44 40 35 31 30 29 28 26 25 21 14

.30 20 27 36 51 63 89 141 217 276 285 255 212 172 115 85 71 63 58 55 51 48 44 40 36 32 30 29 28 26 25 21 14

.40 17 23 31 42 .50 16 22 30 40 .75 13 17 24 32 1.0 11 13 17 24

48 58 79 120 185 246 272 260 228 156 108 82 69 62 57 53 49 45 41 37 33 30 29 28 27 25 45 54 70 104 158 216 253 258 238 173 120 89 72 63 58 54 50 46 42 37 33 30 29 28 27 25 35 39 45 54 72 104 147 189 219 231 182 135 100 79 67 58 53 43 44 40 35 32 30 29 27 26 26 29 32 35 40 46 58 79 110 184 221 202 158 118 90 68 58 52 46 42 38 34 31 29 28 26

22 14 22 14 22 15 23 15

1.5 8 10 12 15 17 19 21 23 25 28 31 35 40 62 107 163 199 193 165 114 81 61 52 46 42 37 33 31 28 27 23 16

2.0 5 7 9 10 11 12 13 14 15 17 18 20 22 27 35 50 80 125 165 184 152 99 64 53 47 42 38 34 29 23 24 17

2.5 3 5 6 8 8 9 10 10 11 12 13 14 15 18 22 27 35 50 78 134 173 154 96 64 52 46 42 37 31 28 25 18

3.0 2 3 4 6 6 7 7 8 8 9 9 10 11 12 14 17 21 26 34 61 107 164 145 94 64 52 46 41 33 29 26 19

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.3 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 8 32 98 198 217 192 148 125 108 95 79 72 67 64 63 61 58 56 53 49 45 41 40 40 39 38 36 32 22

.10 0 0 0 1 6 23 73 156 197 194 164 138 118 91 77 70 66 64 62 59 57 54 50 46 41 40 40 39 38 36 32 22

.20 0 0 0 1 4 17 54 122 172 187 171 149 128 98 81 72 67 64 63 60 57 54 51 46 42 40 40 39 38 36 32 22

.30 0 0 0 0 0 3 12 40 95 146 173 172 157 120 94 79 71 67 64 61 58 55 52 48 43 40 40 39 38 37 33 23

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 2 9 30 73 122 156 167 160 128 100 83 73 68 65 62 59 56 52 48 44 41 40 39 38 37 33 23 0 1 6 22 56 100 137 157 159 135 107 87 76 69 65 62 59 56 53 49 44 41 40 40 38 37 33 23 0 0 1 3 9 26 53 86 115 143 134 113 93 80 72 65 62 58 54 51 46 42 40 40 39 37 33 23 0 0 0 0 1 5 14 32 57 111 138 132 113 94 81 69 64 60 56 52 48 44 41 40 39 37 34 24

1.5 0 0 0 0 0 0 0 0 0 0 0 0 1 8 34 74 111 126 121 99 80 67 61 56 53 49 44 41 39 38 35 26

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 11 33 66 97 118 108 84 67 60 56 52 48 44 40 39 36 27

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 12 32 74 106 112 83 67 60 56 52 48 41 39 37 28

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 21 54 98 107 81 67 60 55 51 43 40 37 29

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.3 HR * * *

IA/P = 0.50

--+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 1 6 16 27 36 41 44 46 48 49 51 52 52 52 52 52 52 51 50 50 49 49 49 48 46 33

.10 0 0 0 0 0 0 1 4 12 22 31 38 42 45 48 49 51 52 52 52 52 52 52 51 50 50 49 49 49 48 46 33

.20 0 0 0 0 0 0 0 3 9 18 27 34 39 44 47 49 50 51 52 52 52 52 52 51 50 50 49 49 49 48 46 33

.30 0 0 0 0 0 0 0 2 7 14 23 30 36 43 46 48 50 51 52 52 52 52 52 51 50 50 49 49 49 48 46 33

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 1 5 11 19 26 33 41 46 48 49 51 52 52 52 52 52 52 50 50 49 49 49 48 46 33 0 0 0 1 4 9 15 23 30 39 44 47 49 50 51 52 52 52 52 52 50 50 49 49 49 48 46 33 0 0 0 0 2 4 8 14 20 31 40 44 47 49 51 52 52 52 52 52 50 50 50 49 49 48 46 34 0 0 0 0 0 0 0 1 2 9 20 31 39 44 47 50 51 52 52 52 52 50 50 50 49 49 47 36

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 9 18 28 36 44 48 51 52 52 52 51 50 50 49 49 48 37

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 12 21 33 42 48 51 52 52 52 51 50 49 49 48 38

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 15 27 40 48 51 52 52 52 51 50 49 48 40

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 11 25 41 48 51 52 52 51 50 49 48 41

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = I

* * * TC = 0.3 HR * * *

SHEET 3 OF 10

5-11 A-1-51

5-12 A-1-52

Exhibit 5-I, continued: Tabular hydrograph unit discharges (csm/in) for type I rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

9.3

9.9

10.1

10.3

10.5

10.7

11.0

11.4

11.8

12.3

13.0

14.0

15.0

16.0

18.0

24.0

(HR) 9.0

9.6

10.0

10.2

10.4

10.6

10.8

11.2

11.6

12.0

12.6

13.5

14.5

15.5

17.0

20.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.4 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 23 31 42 66 96 157 250 310 304 244 186 149 122 89 73 64 59 56 53 49 46 43 39 35 31 29 29 28 26 25 21 14

.10 22 29 40 61 84 133 211 277 295 261 211 170 138 98 78 66 60 56 54 50 47 43 39 35 31 29 29 28 26 25 21 14

.20 19 26 34 47 56 75 114 178 244 278 267 230 190 128 93 75 65 59 56 52 48 44 40 36 32 30 29 28 27 25 21 14

.30 18 24 33 45 53 67 98 152 213 257 263 241 207 143 102 80 68 61 57 52 49 45 41 37 32 30 29 28 27 25 21 14

.40 15 21 28 38 .50 15 20 27 36 .75 12 16 21 29 1.0 10 12 16 21

43 49 61 86 130 185 233 253 245 188 132 97 77 66 60 55 51 46 42 38 34 30 29 28 27 25 41 46 56 76 112 161 209 238 243 201 146 106 82 69 61 55 51 47 42 38 34 31 29 29 27 25 32 35 39 46 57 77 108 147 184 220 200 157 118 91 74 61 55 50 45 40 36 32 30 29 27 26 24 26 29 32 36 40 48 61 83 147 202 212 178 138 105 75 62 54 47 43 39 35 31 29 28 26

22 14 22 14 22 15 23 16

1.5 8 9 11 14 16 17 19 21 23 25 28 31 35 50 83 134 179 193 177 131 92 65 53 47 42 38 34 31 29 27 24 16

2.0 5 6 8 10 10 11 12 13 14 15 17 18 20 25 31 42 64 102 144 179 163 111 70 55 48 43 39 35 30 28 25 17

2.5 3 4 6 7 8 8 9 9 10 11 12 13 14 16 20 24 30 42 63 114 160 170 107 70 54 47 43 38 31 29 25 18

3.0 2 3 4 5 6 6 7 7 8 8 9 9 10 11 13 16 19 23 30 51 90 148 161 104 69 54 47 42 34 29 26 19

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.4 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 3 14 48 115 184 192 178 148 127 111 88 77 70 66 64 62 59 56 54 50 46 41 40 40 39 38 36 32 22

.10 0 0 0 0 2 10 35 89 152 179 178 158 137 105 85 75 69 65 63 60 58 55 51 47 42 40 40 39 38 36 32 22

.20 0 0 0 0 2 7 26 68 124 161 172 163 146 113 90 78 70 66 64 61 58 55 52 47 43 40 40 39 38 37 33 22

.30 0 0 0 0 1 5 19 52 100 140 162 162 151 120 96 81 72 67 64 61 59 55 52 48 43 41 40 39 38 37 33 23

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 1 4 14 39 80 120 148 158 142 114 92 79 71 67 63 60 57 53 49 45 41 40 40 38 37 33 23 0 1 3 10 29 63 101 132 152 145 120 97 82 73 68 63 60 57 53 50 45 41 40 40 38 37 33 23 0 0 0 1 4 13 31 58 87 130 138 123 103 87 77 68 63 59 55 51 47 43 41 40 39 37 34 24 0 0 0 0 0 2 7 18 36 86 125 134 122 104 88 73 66 61 57 53 49 45 41 40 39 38 34 24

1.5 0 0 0 0 0 0 0 0 0 0 0 0 1 0 36 75 109 124 120 100 81 68 61 56 53 49 44 41 40 38 35 26

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 6 22 50 83 116 116 91 70 61 57 53 49 45 40 39 36 27

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 8 22 60 97 111 88 70 61 56 53 48 42 39 37 28

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 14 43 89 106 86 69 61 56 52 44 40 37 29

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.4 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 2 8 17 27 34 40 44 47 49 50 51 51 51 51 51 51 51 50 50 49 49 49 48 46 33

.10 0 0 0 0 0 0 0 0 2 6 13 22 30 40 45 47 49 50 51 51 51 51 51 51 50 50 50 49 49 48 46 34

.20 0 0 0 0 0 0 0 0 0 1 4 10 18 33 41 45 48 49 51 51 51 51 51 51 50 50 50 49 49 49 46 34

.30 0 0 0 0 0 0 0 0 0 0 1 3 8 22 35 42 46 48 50 51 51 51 51 51 51 50 50 49 49 49 47 35

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 0 1 2 6 19 32 40 45 47 49 51 51 51 51 51 51 50 50 49 49 49 47 35 0 0 0 0 0 0 0 0 2 9 23 34 41 45 48 50 51 51 51 51 51 50 50 49 49 49 47 35 0 0 0 0 0 0 0 0 1 5 14 26 35 42 46 49 50 51 51 51 51 50 50 50 49 49 47 36 0 0 0 0 0 0 0 0 0 0 1 5 14 25 35 44 48 50 51 51 51 51 50 50 49 49 48 37

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2

13 27 39 47 50 51 51 51 51 50 49 49 48 39

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 9 21 36 47 50 51 51 51 51 50 49 48 40

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 6 19 37 47 50 51 51 51 50 49 48 42

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 8 25 40 48 50 51 51 50 50 49 43

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = I

* * * TC = 0.4 HR * * *

SHEET 4 OF 10

GaSWCC

GaSWCC

Exhibit 5-I, continued: Tabular hydrograph unit discharges (csm/in) for type I rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

9.3

9.9

10.1

10.3

10.5

10.7

11.0

11.4

11.8

12.3

13.0

14.0

15.0

16.0

18.0

24.0

(HR) 9.0

9.6

10.0

10.2

10.4

10.6

10.8

11.2

11.6

12.0

12.6

13.5

14.5

15.5

17.0

20.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.5 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 21 28 39 56 73 111 175 247 282 271 229 186 152 108 84 71 63 58 55 51 47 44 40 35 31 30 29 28 26 25 21 14

.10 20 27 36 52 66 96 149 214 259 267 242 204 169 119 90 74 65 59 55 51 48 44 40 36 32 30 29 28 26 25 21 14

.20 17 23 31 42 49 60 84 127 185 234 256 247 219 156 112 86 72 63 58 53 49 45 41 37 33 30 29 28 27 25 22 14

.30 16 22 30 40 46 55 74 110 160 210 241 245 227 171 123 93 76 66 59 54 50 46 42 38 33 30 29 28 27 25 22 14

.40 14 19 26 35 38 43 51 67 95 138 186 222 237 210 157 115 89 73 64 57 52 47 43 39 35 31 29 29 27 25 22 15

.50 14 18 25 33 37 41 48 61 84 120 164 203 229 216 170 126 96 77 66 58 53 48 43 39 35 31 30 29 27 25 22 15

.75 11 14 19 26 29 32 35 40 48 61 83 114 148 202 210 176 137 106 84 66 57 51 46 41 37 33 30 29 28 26 22 15

1.0 10 11 15 19 21 24 26 29 32 36 41 50 65 116 176 203 190 156 122 85 67 56 49 44 40 35 32 30 28 26 23 16

1.5 7 9 11 13 14 16 17 19 21 23 25 28 31 42 67 110 157 187 133 146 104 72 55 48 43 39 35 32 29 27 24 17

2.0 4 6 7 9 10 10 11 12 13 14 15 17 18 22 27 36 53 83 123 175 175 124 77 57 49 44 40 35 30 28 25 18

2.5 3 4 5 7 7 8 8 9 9 10 11 12 13 15 18 22 27 36 53 97 146 166 119 76 57 49 44 39 32 29 25 18

3.0 1 2 3 5 5 6 6 6 7 8 8 9 9 11 12 15 17 21 27 43 76 135 158 114 75 57 48 43 35 30 26 19

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.5 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 1 6 22 64 123 168 174 165 143 126 100 84 74 68 65 63 60 57 54 51 47 42 40 40 39 38 36 32 22

.10 0 0 0 1 5 16 48 98 144 164 165 150 134 106 87 77 70 66 63 60 58 55 51 47 42 40 40 39 38 36 32 22

.20 0 0 0 0 1 3 12 36 77 122 150 160 154 126 101 85 75 69 65 62 59 56 52 48 44 41 40 39 38 37 33 23

.30 0 0 0 0 0 2 9 27 60 101 134 151 153 132 107 89 77 70 66 63 60 56 53 49 44 41 40 40 38 37 33 23

.40 0 0 0 0 0 0 2 6 20 47 83 117 140 148 125 102 86 76 69 64 61 57 54 50 46 42 40 40 39 37 33 23

.50 0 0 0 0 0 0 1 5 15 36 68 101 127 144 130 108 90 78 71 65 62 58 54 50 46 42 40 40 39 37 33 23

.75 0 0 0 0 0 0 0 2 6 17 36 60 87 125 133 121 103 88 78 68 63 59 55 52 47 43 41 40 39 37 34 24

1.0 0 0 0 0 0 0 0 0 0 1 3 9 21 62 106 130 126 112 96 78 69 62 57 54 50 46 42 40 39 38 34 25

1.5 0 0 0 0 0 0 0 0 0 0 0 0 1 6 23 56 92 115 120 106 87 71 62 57 53 49 45 42 40 38 35 26

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 14 36 67 104 113 96 74 63 58 54 50 46 40 39 36 27

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 15 47 85 109 93 73 63 57 53 49 42 40 37 28

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 9 32 77 105 90 72 62 57 53 45 40 38 30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.5 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 1 4 10 18 26 33 41 45 47 49 50 50 50 50 50 50 50 50 50 50 49 49 48 46 33

.10 0 0 0 0 0 0 0 1 3 8 15 22 30 39 44 47 49 50 50 50 50 50 50 50 50 50 50 49 49 48 46 34

.20 0 0 0 0 0 0 0 0 2 6 12 19 26 37 43 46 48 50 50 50 50 50 50 50 50 50 50 49 49 48 46 34

.30 0 0 0 0 0 0 0 0 1 4 9 16 23 34 41 45 48 49 50 50 50 50 50 50 50 50 50 49 49 49 46 34

.40 0 0 0 0 0 0 0 0 1 3 7 13 19 31 39 44 47 49 50 50 50 50 50 50 50 50 50 49 49 49 46 34

.50 0 0 0 0 0 0 0 0 1 2 6 10 16 28 37 43 46 48 50 50 50 50 50 50 50 50 50 49 49 49 46 34

.75 0 0 0 0 0 0 0 0 0 1 3 6 10 20 30 38 43 46 48 50 50 50 50 50 50 50 50 49 49 49 47 35

1.0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 10 20 30 38 43 47 49 50 50 50 50 50 50 50 49 49 47 36

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 14 23 31 41 46 49 50 50 50 50 50 50 49 49 48 38

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 13 25 36 45 49 50 50 50 50 50 49 49 48 39

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 12 23 37 46 49 50 50 50 50 50 49 48 40

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 8 21 37 46 49 50 50 50 50 49 48 42

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = I

* * * TC = 0.5 HR * * *

SHEET 5 OF 10

5-13 A-1-53

5-14 A-1-54

Exhibit 5-I, continued: Tabular hydrograph unit discharges (csm/in) for type I rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

9.3

9.9

10.1

10.3

10.5

10.7

11.0

11.4

11.8

12.3

13.0

14.0

15.0

16.0

18.0

24.0

(HR) 9.0

9.6

10.0

10.2

10.4

10.6

10.8

11.2

11.6

12.0

12.6

13.5

14.5

15.5

17.0

20.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.75 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 16 22 30 41 47 59 82 119 167 209 229 233 212 161 122 97 80 69 62 56 51 46 42 38 33 31 29 28 27 25 22 14

.10 14 19 26 35 39 44 54 72 104 146 188 215 227 197 150 116 93 77 68 59 53 48 43 39 35 31 30 29 27 25 22 15

.20 13 16 22 30 33 37 42 50 65 91 128 168 200 218 183 142 110 89 75 63 56 49 44 40 36 32 30 29 27 26 22 15

.30 12 16 21 28 31 35 39 46 59 80 112 149 183 214 191 151 118 94 79 65 57 50 45 41 36 32 30 29 27 26 22 15

.40 12 15 20 27 .50 11 13 18 24 .75 10 12 15 21 1.0 8 10 12 16

30 33 37 43 54 71 98 132 166 207 197 161 126 100 83 67 58 51 45 41 37 33 30 29 27 26 26 29 32 36 41 49 64 87 117 178 204 186 152 120 96 74 62 53 47 42 38 34 31 29 28 26 23 25 28 31 35 40 49 63 83 136 180 190 171 142 115 35 69 57 49 44 39 35 32 30 28 26 17 19 21 23 25 28 31 35 42 66 110 158 136 180 157 116 66 65 53 46 42 38 34 31 28 27

22 15 23 15 23 16 23 16

1.5 5 7 8 10 11 12 13 14 15 17 18 20 22 27 35 52 83 124 159 174 147 102 69 54 47 42 38 34 30 28 24 17

2.0 3 5 6 8 8 9 9 10 11 12 13 14 15 18 22 27 36 52 80 131 165 148 99 68 54 47 42 38 31 28 25 18

2.5 2 3 4 5 6 6 7 7 8 9 9 10 11 12 14 17 21 26 35 63 107 157 141 96 67 54 46 42 34 29 26 19

3.0 1 1 2 3 4 4 4 5 5 6 6 7 7 8 10 11 13 15 19 26 42 86 151 141 101 71 55 47 38 31 27 20

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.75 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 1 4 14 35 69 105 131 143 146 124 104 89 79 72 68 64 60 56 53 49 44 41 40 40 38 37 33 23

.10 0 0 0 0 0 1 3 10 27 55 88 117 134 142 118 100 87 77 71 66 62 58 54 50 46 42 40 40 39 37 33 23

.20 0 0 0 0 0 0 2 7 20 43 73 102 123 137 123 105 90 80 73 66 62 58 54 50 46 42 40 40 39 37 33 23

.30 0 0 0 0 0 0 0 1 5 15 34 60 88 128 134 118 101 88 78 69 64 60 55 52 48 43 41 40 39 37 34 24

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 1 4 12 27 49 75 118 131 121 105 91 80 71 65 60 56 52 48 44 41 40 39 37 34 24 0 0 0 0 1 3 9 21 39 87 122 128 116 101 88 75 68 62 57 53 49 45 42 40 39 38 34 24 0 0 0 0 0 1 4 10 21 56 95 118 121 110 98 82 72 64 58 54 50 46 42 41 39 38 34 25 0 0 0 0 0 0 0 1 2 12 39 76 106 119 115 98 82 69 61 57 53 49 44 42 40 38 35 26

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 14 37 67 95 112 105 85 69 61 56 52 48 44 40 39 36 27

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 15 35 74 102 107 84 69 61 56 52 48 41 39 37 28

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 23 55 94 103 82 68 60 56 52 44 40 37 29

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 15 50 93 100 81 68 60 55 47 41 38 30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.75 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 0 1 2 5 10 17 29 37 42 45 48 49 49 49 49 49 49 49 49 49 49 49 49 47 34

.10 0 0 0 0 0 0 0 0 0 2 4 8 14 26 35 41 45 47 49 49 49 49 49 49 49 49 49 49 49 49 47 35

.20 0 0 0 0 0 0 0 0 0 1 3 7 11 23 33 39 44 47 48 49 49 49 49 49 49 49 49 49 49 49 47 35

.30 0 0 0 0 0 0 0 0 0 1 2 5 9 20 30 38 43 46 48 49 49 49 49 49 49 49 49 49 49 49 47 35

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 1 2 4 8 17 28 36 41 45 47 49 49 49 49 49 49 49 49 49 49 49 47 35 0 0 0 0 0 0 1 3 6 15 25 34 40 44 47 48 49 49 49 49 49 49 49 49 49 49 47 35 0 0 0 0 0 0 1 1 3 9 18 27 35 40 44 47 48 49 49 49 49 49 49 49 49 49 47 36 0 0 0 0 0 0 0 0 1 4 10 18 27 35 40 45 48 49 49 49 49 49 49 49 49 49 48 37

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 13 21 29 38 44 48 49 49 49 49 49 49 49 49 48 38

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 9 15 26 36 44 48 49 49 49 49 49 49 49 48 39

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 11 21 34 44 48 48 48 48 48 48 48 48 40

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 3 19 35 44 48 48 48 48 48 48 48 42

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = I

* * * TC = 0.75 HR * * *

SHEET 6 OF 10

GaSWCC

GaSWCC

Exhibit 5-I, continued: Tabular hydrograph unit discharges (csm/in) for type I rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

9.3

9.9

10.1

10.3

10.5

10.7

11.0

11.4

11.8

12.3

13.0

14.0

15.0

16.0

18.0

24.0

(HR) 9.0

9.6

10.0

10.2

10.4

10.6

10.8

11.2

11.6

12.0

12.6

13.5

14.5

15.5

17.0

20.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 1.0 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 14 19 25 34 38 46 58 79 106 136 165 186 202 185 153 122 101 85 74 63 56 50 44 40 35 32 30 29 27 26 22 15

.10 13 18 24 32 36 42 53 70 94 122 151 174 194 188 160 130 106 89 77 65 57 50 44 40 36 32 30 29 27 26 22 15

.20 12 15 21 28 31 34 40 49 63 83 109 137 162 190 180 152 124 102 86 70 61 53 46 41 37 33 31 29 27 26 22 15

.30 12 15 20 26 29 33 37 45 57 75 98 124 149 187 183 159 131 107 90 73 62 53 47 42 37 33 31 29 28 26 23 15

.40 10 13 17 23 .50 10 13 16 22 .75 9 11 14 19 1.0 8 9 11 15

25 28 31 35 42 52 67 88 112 160 183 176 151 125 103 81 67 56 48 43 39 35 31 30 28 26 24 27 30 33 39 48 61 79 101 148 181 181 157 131 108 84 69 58 49 43 39 35 32 30 28 26 21 23 26 29 33 38 47 59 75 115 153 172 167 148 125 96 77 62 51 45 40 36 33 30 28 27 16 17 19 21 23 26 29 33 40 61 95 134 162 169 157 126 97 72 57 49 43 39 35 32 29 27

23 15 23 16 23 16 24 16

1.5 5 6 8 10 10 11 12 13 14 16 17 19 21 25 33 48 74 107 138 160 148 111 76 59 50 44 39 35 30 29 25 17

2.0 3 4 6 7 8 8 9 9 10 11 12 13 14 17 20 25 33 48 71 115 153 153 108 75 58 49 43 39 32 29 25 18

2.5 2 3 4 5 5 6 6 7 7 8 9 9 10 12 14 16 20 25 33 56 94 139 147 104 74 58 49 43 34 30 26 19

3.0 1 1 2 3 3 4 4 4 5 5 6 6 7 8 9 10 12 14 17 24 38 76 131 143 108 78 60 50 39 32 27 20

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 1.0 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 1 2 7 17 34 55 79 99 114 128 114 100 89 80 74 68 63 59 54 51 46 43 41 40 39 37 33 23

.10 0 0 0 0 0 0 2 5 13 27 46 68 89 116 124 110 98 87 79 71 65 60 56 52 48 43 41 40 39 37 34 24

.20 0 0 0 0 0 0 1 4 10 21 37 58 78 109 121 113 101 90 81 72 66 61 56 52 48 44 41 40 39 37 34 24

.30 0 0 0 0 0 0 0 1 3 8 17 31 49 87 113 118 109 98 87 76 69 63 57 53 49 45 42 40 39 38 34 24

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 1 2 6 13 25 41 78 107 117 111 101 90 78 70 63 58 54 50 45 42 41 39 38 34 25 0 0 0 0 2 5 10 20 34 69 100 115 113 103 93 80 71 64 58 54 50 46 42 41 39 38 34 25 0 0 0 0 0 1 2 5 10 31 61 90 107 110 104 90 79 69 61 56 52 48 44 41 40 38 35 25 0 0 0 0 0 0 0 1 3 12 33 61 89 105 109 99 86 73 64 58 54 50 45 42 40 38 35 26

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 13 31 55 80 104 104 88 73 63 58 53 49 45 41 39 36 27

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 8 20 51 82 100 90 74 64 58 54 50 42 40 37 28

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 13 37 76 98 88 73 64 58 53 45 41 38 30

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 9 34 77 95 86 73 63 58 49 42 38 31

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 1.0 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 0 0 1 3 5 9 18 28 35 40 44 47 48 48 48 48 48 48 48 48 48 48 48 47 35

.10 0 0 0 0 0 0 0 0 0 1 2 4 7 16 25 33 39 43 46 48 48 48 48 48 48 48 48 46 48 48 47 35

.20 0 0 0 0 0 0 0 0 0 1 2 3 6 14 23 31 38 42 45 47 48 48 48 48 48 48 48 48 48 48 47 36

.30 0 0 0 0 0 0 0 0 0 0 1 3 5 12 21 29 36 41 44 47 48 48 48 48 48 48 48 48 48 48 47 36

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 0 1 2 4 10 19 27 34 40 44 47 48 48 48 48 48 48 48 48 48 48 47 36 0 0 0 0 0 0 1 2 3 8 16 25 33 38 43 46 48 48 48 48 48 48 48 48 48 48 47 36 0 0 0 0 0 0 1 2 3 8 15 23 30 36 41 45 47 48 48 48 48 48 48 48 48 48 47 36 0 0 0 0 0 0 0 0 0 2 5 11 19 27 33 41 45 47 48 48 48 48 48 48 48 48 48 37

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 5 11 17 28 37 44 47 48 48 48 48 48 48 48 48 39

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 7 16 26 38 45 47 48 48 48 48 48 48 48 40

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 12 24 38 45 47 47 47 47 47 47 47 41

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 14 29 40 46 47 47 47 47 47 47 42

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = I

* * * TC = 1.0 HR * * *

SHEET 7 OF 10

5-15 A-1-55

5-16 A-1-56

Exhibit 5-I, continued: Tabular hydrograph unit discharges (csm/in) for type I rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

9.3

9.9

10.1

10.3

10.5

10.7

11.0

11.4

11.8

12.3

13.0

14.0

15.0

16.0

18.0

24.0

(HR) 9.0

9.6

10.0

10.2

10.4

10.6

10.8

11.2

11.6

12.0

12.6

13.5

14.5

15.5

17.0

20.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 1.25 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 12 16 22 29 33 38 47 61 80 103 127 149 164 180 163 138 115 98 85 71 62 53 47 41 37 33 31 29 27 26 22 15

.10 11 14 19 25 28 31 36 44 55 72 92 116 138 167 175 156 132 111 95 77 66 56 48 43 38 34 31 30 28 26 23 15

.20 11 14 18 24 27 30 34 40 50 65 83 105 127 160 172 160 138 116 99 80 68 57 49 43 39 34 31 30 28 26 23 15

.30 10 12 16 21 23 25 28 32 38 46 58 75 95 136 164 169 154 132 112 89 74 61 51 45 40 36 32 30 28 26 23 16

.40 9 12 15 20 22 24 27 30 35 42 53 68 86 126 157 167 157 137 117 92 76 62 52 46 40 36 33 30 28 26 23 16 .50 9 11 13 17 19 21 23 26 29 33 39 49 61 97 134 160 165 152 132 104 84 67 55 47 42 37 33 31 23 27 23 16 .75 7 9 11 14 15 17 18 20 22 25 28 32 38 59 90 124 150 159 152 126 101 77 60 51 45 40 35 32 29 27 24 17 1.0 6 8 10 12 13 14 15 17 19 20 23 25 29 40 60 91 123 148 157 144 118 88 66 54 47 41 37 33 29 27 24 17

1.5 4 6 7 9 9 10 11 12 13 14 15 16 18 22 28 40 59 85 114 145 150 121 86 65 54 46 41 37 31 28 25 13

2.0 2 3 5 6 6 7 7 8 9 9 10 11 11 13 16 19 24 33 47 80 119 144 124 90 68 55 47 42 33 29 26 19

2.5 1 2 3 4 4 5 5 6 6 7 7 8 8 10 11 13 16 19 24 38 65 111 140 120 88 67 54 47 37 31 27 20

3.0 1 1 2 2 3 3 3 4 4 5 5 5 6 7 8 9 11 13 15 21 32 62 114 136 116 86 66 54 41 33 27 20

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 1.25 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 1 4 10 21 35 53 71 86 106 115 104 94 86 79 72 66 61 56 52 48 44 41 40 39 37 34 24

.10 0 0 0 0 0 0 1 3 8 16 29 45 62 92 107 113 101 92 84 75 69 63 58 53 49 45 42 41 39 38 34 24

.20 0 0 0 0 0 0 1 2 6 13 23 37 54 84 104 110 104 94 86 77 70 64 58 54 49 45 42 41 39 38 34 24

.30 0 0 0 0 0 0 0 0 2 4 10 19 31 62 90 106 109 101 92 81 73 66 60 55 51 46 43 41 39 38 34 25

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 1 3 8 15 26 55 83 102 107 103 94 83 74 67 60 56 51 47 43 41 39 38 35 25 0 0 0 0 0 1 3 6 12 33 62 88 103 106 100 88 78 69 62 57 53 48 44 42 40 38 35 25 0 0 0 0 0 0 0 1 3 12 31 56 80 97 103 97 87 75 65 59 55 50 46 43 40 39 35 26 0 0 0 0 0 0 0 0 1 4 13 32 56 79 95 101 94 80 69 61 56 52 48 44 40 39 36 27

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 13 30 51 81 98 94 79 68 61 56 52 47 42 39 36 28

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 13 37 66 95 95 78 68 61 56 51 44 40 37 29

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 9 26 61 93 89 77 67 60 55 47 41 38 30

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 6 24 64 91 87 76 66 60 50 43 39 31

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 1.25 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 0 0 1 2 3 6 13 21 29 35 40 43 47 47 47 47 47 47 47 47 47 47 47 47 36

.10 0 0 0 0 0 0 0 0 0 0 1 3 5 11 19 27 34 39 42 47 47 47 47 47 47 47 47 47 47 47 47 36

.20 0 0 0 0 0 0 0 0 0 0 1 2 4 9 17 25 32 37 41 46 47 47 47 47 47 47 47 47 47 47 47 36

.30 0 0 0 0 0 0 0 0 0 0 1 2 3 8 15 23 30 36 40 45 47 47 47 47 47 47 47 47 47 47 47 36

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 0 0 1 2 7 13 21 28 35 39 45 47 47 47 47 47 47 47 47 47 47 47 37 0 0 0 0 0 0 0 1 2 6 12 19 27 33 38 44 46 47 47 47 47 47 47 47 47 47 47 37 0 0 0 0 0 0 0 0 1 3 8 14 21 28 34 41 45 47 47 47 47 47 47 47 47 47 47 37 0 0 0 0 0 0 0 0 0 1 2 5 11 17 24 34 41 46 47 47 47 47 47 47 47 47 47 38

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 5 10 19 29 39 45 47 47 47 47 47 47 47 47 40

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 9 18 30 41 46 47 47 47 47 47 47 47 41

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 7 17 31 41 46 47 47 47 47 47 47 42

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 6 18 32 42 46 47 47 47 47 47 43

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = I

* * * TC = 1.25 HR * * *

SHEET 8 OF 10

GaSWCC

GaSWCC

Exhibit 5-I, continued: Tabular hydrograph unit discharges (csm/in) for type I rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

9.3

9.9

10.1

10.3

10.5

10.7

11.0

11.4

11.8

12.3

13.0

14.0

15.0

16.0

18.0

24.0

(HR) 9.0

9.6

10.0

10.2

10.4

10.6

10.8

11.2

11.6

12.0

12.6

13.5

14.5

15.5

17.0

20.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 1.5 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 11 14 19 25 28 32 39 48 60 76 94 112 129 151 163 147 130 112 97 81 69 59 50 44 39 35 32 30 28 26 23 15

.10 10 12 16 22 24 27 30 36 44 55 69 86 103 135 152 159 143 125 108 88 75 62 52 46 41 36 32 30 28 26 23 16

.20 9 11 14 19 21 23 25 29 34 41 50 63 78 112 140 155 152 138 121 98 81 67 55 48 42 37 33 31 28 27 23 16

.30 9 11 14 18 20 22 24 27 31 38 46 57 71 104 133 151 154 141 125 101 84 68 56 48 43 33 34 31 29 27 23 16

.40 8 10 13 17 19 21 23 26 30 35 42 52 65 96 126 147 152 144 129 105 87 70 57 49 43 38 34 31 29 27 23 16 .50 8 9 12 15 17 18 20 22 25 28 33 39 48 73 104 131 148 151 140 117 95 75 60 51 45 40 35 32 29 27 24 17 .75 7 8 11 13 15 16 18 19 21 24 27 32 38 56 82 110 133 146 144 127 106 83 65 54 47 41 36 33 29 27 24 17 1.0 5 7 9 11 11 12 13 15 16 18 19 22 24 32 47 69 96 122 139 145 127 99 74 60 51 44 39 35 30 28 24 17

1.5 4 5 6 8 8 9 10 10 11 12 13 14 16 19 24 32 46 66 90 124 139 128 97 73 59 50 44 39 32 29 25 18

2.0 2 3 4 5 5 6 6 7 7 8 9 9 10 12 14 17 21 27 38 63 96 135 129 100 76 61 51 44 35 30 26 19

2.5 1 2 2 3 4 4 4 5 5 6 6 7 7 8 10 11 14 16 20 31 51 91 132 124 98 75 60 51 39 32 27 20

3.0 0 1 1 2 2 2 2 3 3 3 4 4 5 6 7 8 9 10 12 16 23 42 86 123 128 101 77 62 45 35 25 21

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 1.5 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 1 3 7 13 21 33 46 60 83 97 106 97 90 84 76 70 64 59 54 50 45 43 41 39 38 34 25

.10 0 0 0 0 0 0 1 2 5 10 18 28 40 66 86 98 103 95 88 80 73 66 60 55 51 47 43 41 39 38 35 25

.20 0 0 0 0 0 0 0 1 4 8 14 23 34 60 81 95 101 97 90 81 74 67 61 56 52 47 44 41 40 38 35 25

.30 0 0 0 0 0 0 0 0 1 3 6 12 19 41 65 85 98 100 95 85 77 69 62 57 53 48 44 42 40 38 35 25

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 1 2 5 9 16 36 59 80 94 99 96 87 79 70 63 58 53 49 45 42 40 38 35 26 0 0 0 0 1 2 4 8 13 31 54 75 91 98 97 88 80 71 64 58 54 49 45 42 40 38 35 26 0 0 0 0 0 0 1 2 4 13 28 49 69 85 95 95 87 76 67 61 56 51 47 44 40 39 36 26 0 0 0 0 0 0 0 0 1 5 13 29 49 69 84 95 92 81 71 63 58 53 49 45 41 39 36 27

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 9 20 35 63 84 92 83 72 64 58 54 49 43 40 37 28

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 9 25 50 79 90 81 71 63 58 53 45 41 38 29

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 6 18 46 79 88 80 70 63 57 49 42 38 31

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 17 50 79 87 79 70 62 52 45 30 32

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC =1. 5 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 0 0 0 1 2 3 8 15 22 29 34 39 44 46 46 46 46 46 46 46 46 46 46 46 37

.10 0 0 0 0 0 0 0 0 0 0 0 1 2 5 10 17 24 30 35 41 46 46 46 46 46 46 46 46 46 46 46 37

.20 0 0 0 0 0 0 0 0 0 0 0 1 1 4 9 15 22 28 34 40 45 46 46 46 46 46 46 46 46 46 46 37

.30 0 0 0 0 0 0 0 0 0 0 0 0 1 3 7 13 20 27 33 39 44 46 46 46 46 46 46 46 46 46 46 38

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 0 0 0 1 3 6 12 18 25 31 38 44 46 46 46 46 46 46 46 46 46 46 38 0 0 0 0 0 0 0 0 1 2 5 10 17 23 30 37 43 46 46 46 46 46 46 46 46 46 46 38 0 0 0 0 0 0 0 0 0 1 3 7 12 19 25 33 40 45 46 46 46 46 46 46 46 46 46 38 0 0 0 0 0 0 0 0 0 0 1 2 5 10 15 25 33 42 46 46 46 46 46 46 46 46 46 39

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 7 14 23 34 43 46 46 46 46 46 46 46 46 40

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 11 22 35 43 46 46 46 46 46 46 46 42

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 10 23 36 43 46 46 46 46 46 46 43

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 14 27 38 44 46 46 46 46 46 44

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = I

* * * TC = 1.5 HR * * *

SHEET 9 OF 10

5-17 A-1-57

5-18 A-1-58

Exhibit 5-I, continued: Tabular hydrograph unit discharges (csm/in) for type I rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

9.3

9.9

10.1

10.3

10.5

10.7

11.0

11.4

11.8

12.3

13.0

14.0

15.0

16.0

18.0

24.0

(HR) 9.0

9.6

10.0

10.2

10.4

10.6

10.8

11.2

11.6

12.0

12.6

13.5

14.5

15.5

17.0

20.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 2.0 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 9 11 14 19 21 24 28 33 40 49 59 70 82 106 123 138 138 125 115 97 83 70 59 50 44 39 35 32 29 27 23 16

.10 8 10 13 17 18 20 23 26 31 37 45 54 65 89 110 125 135 130 123 106 90 75 62 53 46 40 36 33 29 27 24 16

.20 8 10 12 16 17 19 22 25 29 34 41 50 60 83 105 121 132 131 125 109 92 77 63 53 46 41 36 33 29 27 24 17

.30 7 9 11 14 15 17 18 21 23 27 32 38 46 66 89 109 123 131 129 117 100 82 66 56 48 42 38 34 30 28 24 17

.40 7 .50 6 .75 5 1.0 4

8 10 13 8 10 13 7 8 11 578

15 16 18 20 22 25 30 35 43 61 83 104 120 131 131 119 103 84 68 57 49 43 38 34 30 28 14 15 17 19 21 24 28 33 39 56 78 99 116 127 130 121 106 86 69 58 50 44 39 35 30 28 12 13 14 15 16 18 20 23 27 38 53 73 93 111 123 127 118 98 77 63 54 47 41 37 31 28
9 10 11 12 13 14 15 17 18 24 32 45 63 83 102 122 126 113 89 71 59 51 44 39 32 29

24 17 24 17 25 17 25 18

1.5 3 4 5 6 7 7 8 8 9 10 10 11 12 15 18 23 32 44 60 88 111 123 110 87 70 58 50 44 35 30 26 19

2.0 1 2 3 4 5 5 5 6 6 7 7 8 9 10 12 14 18 23 31 49 74 106 121 107 86 69 58 49 38 32 27 20

2.5 1 1 2 2 3 3 3 4 4 4 5 5 6 7 8 9 11 13 16 22 35 62 101 118 108 88 71 59 44 35 28 21

3.0 0 0 1 1 1 2 2 2 3 3 3 3 4 5 5 6 8 9 10 14 19 34 67 103 116 105 86 70 50 39 29 21

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 2.0 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 1 3 6 10 16 23 31 49 65 77 84 92 86 80 75 69 63 58 53 49 45 43 40 38 35 26

.10 0 0 0 0 0 0 0 1 2 5 9 13 19 35 53 68 79 85 90 83 77 71 64 59 55 50 46 43 40 39 35 26

.20 0 0 0 0 0 0 0 0 1 2 4 7 11 24 40 57 71 81 89 89 80 73 66 61 56 51 47 44 41 39 35 26

.30 0 0 0 0 0 0 0 0 1 1 3 6 9 20 36 53 68 78 84 88 81 74 67 61 56 52 48 44 41 39 36 26

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 0 1 2 5 12 24 40 57 70 80 87 84 76 69 63 58 53 49 45 41 39 36 27 0 0 0 0 0 0 1 2 4 10 21 36 53 67 77 87 85 77 69 63 58 54 49 46 41 39 36 27 0 0 0 0 0 0 0 1 2 6 14 26 41 56 69 82 85 80 72 65 60 55 51 47 42 40 36 27 0 0 0 0 0 0 0 0 0 1 4 10 20 34 49 68 81 85 77 69 63 58 53 49 43 40 37 28

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 10 19 38 58 78 83 76 68 62 57 53 45 41 37 29

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 4 13 29 55 77 82 75 68 62 57 48 43 38 30

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 22 51 75 81 75 68 62 53 45 39 32

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 6 25 54 75 80 75 68 57 48 40 33

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 2.0 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 0 0 0 0 1 2 4 8 13 18 24 29 36 41 46 46 46 46 46 46 46 46 46 46 38

.10 0 0 0 0 0 0 0 0 0 0 0 1 1 3 7 12 17 22 28 35 40 45 46 46 46 46 46 46 46 46 46 38

.20 0 0 0 0 0 0 0 0 0 0 0 0 1 2 4 8 13 18 24 31 38 44 46 46 46 46 46 46 46 46 46 39

.30 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 7 12 17 22 30 37 43 45 46 46 46 46 46 46 46 46 39

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 0 0 0 0 1 3 6 11 16 21 29 36 42 45 46 46 46 46 46 46 46 46 39 0 0 0 0 0 0 0 0 0 1 3 5 9 14 20 28 35 42 45 45 45 45 45 45 45 45 45 39 0 0 0 0 0 0 0 0 0 1 2 5 9 13 18 26 33 41 45 45 45 45 45 45 45 45 45 39 0 0 0 0 0 0 0 0 0 0 0 1 3 5 9 16 24 33 42 45 45 45 45 45 45 45 45 40

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 4 8 15 25 36 43 45 45 45 45 45 45 45 42

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 6 14 26 37 43 45 45 45 45 45 45 43

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 15 27 37 43 45 45 45 45 45 44

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 8 19 30 39 44 45 45 45 45 45

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = I

* * * TC = 2.0 HR * * *

SHEET 10 OF 10

GaSWCC

GaSWCC

Exhibit 5-IA: Tabular hydrograph unit discharges (csm/in) for type IA rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

7.3

7.9

8.1

8.3

8.5

8.7

9.0

9.4

9.8

10.3

11.0

12.0

13.0

14.0

16.0

22.0

(HR) 7.0

7.6

8.0

8.2

8.4

8.6

8.8

9.2

9.6

10.0

10.6

11.5

12.5

13.5

15.0

18.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.1 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 28 36 50 143 154 163 140 103 87 76 68 67 65 61 54 49 45 44 44 41 40 39 36 33 32 32 31 30 30 29 26 21

.10 27 32 43 104 130 146 157 145 117 97 83 73 69 65 59 53 48 45 45 42 40 39 37 34 33 32 32 31 30 29 27 22

.20 26 29 37 59 89 116 136 150 147 127 107 91 79 68 63 57 52 47 45 44 41 39 37 35 33 32 32 31 30 29 27 22

.30 25 28 35 53 77 103 125 142 145 133 116 99 86 71 65 59 53 48 46 44 41 39 38 35 33 32 32 31 30 29 27 22

.40 24 26 31 41 .50 24 26 30 39 .75 20 24 27 32 1.0 16 20 24 27

49 68 91 114 132 141 136 122 107 82 70 63 57 52 48 45 43 40 38 36 33 32 32 31 30 29 46 60 81 103 123 135 135 127 114 88 73 65 59 53 49 45 43 40 39 36 33 33 32 31 30 29 35 39 47 60 76 94 111 122 125 114 94 79 68 61 55 48 45 42 39 37 35 33 32 32 30 30 28 30 32 36 41 49 62 77 94 118 122 104 86 74 65 55 49 44 41 39 36 34 33 32 31 30

27 22 27 22 27 22 28 23

1.5 12 15 18 22 23 24 25 27 28 30 32 36 42 61 86 107 112 104 91 73 60 50 44 41 38 36 34 33 31 30 28 23

2.0 7 10 12 15 16 18 19 20 21 22 24 25 26 30 36 50 69 90 106 103 87 67 52 45 41 39 36 34 32 31 29 24

2.5 4 6 8 11 12 13 14 15 16 17 18 19 21 23 26 30 36 49 66 91 101 89 66 51 44 41 38 36 33 31 29 25

3.0 2 3 5 7 8 9 10 11 11 12 13 14 16 18 20 23 25 29 36 55 79 98 86 65 51 44 41 38 34 32 30 25

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.1 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 1 45 65 89 78 64 59 54 54 53 51 50 48 45 44 43 43 43 42 42 41 40 40 40 40 40 39 39 38 33

.10 0 0 0 18 36 55 78 78 69 62 57 55 53 51 50 47 44 44 43 43 42 42 41 40 40 40 40 40 39 39 38 34

.20 0 0 0 13 29 46 67 74 71 65 60 56 54 52 50 48 45 44 43 43 43 42 41 41 40 40 40 40 39 39 38 34

.30 0 0 0 10 22 38 58 69 70 67 62 58 56 52 51 48 46 44 44 43 43 42 41 41 40 40 40 40 39 39 38 34

.40 0 0 0 2 .50 0 0 0 1 .75 0 0 0 0 1.0 0 0 0 0

7 17 31 49 62 67 67 64 60 55 52 50 48 45 44 43 43 42 42 41 40 40 40 40 39 39 5 13 25 41 55 63 66 64 61 56 53 51 48 46 44 43 43 42 42 41 40 40 40 40 39 39 0 2 6 13 24 36 47 55 61 61 57 54 51 49 47 44 43 43 42 41 41 40 40 40 40 39 0 1 3 8 15 25 36 46 53 60 59 55 53 50 48 45 44 43 42 42 41 40 40 40 40 39

38 34 38 34 38 34 38 35

1.5 0 0 0 0 0 0 0 0 1 2 5 9 15 31 47 55 57 56 53 50 46 44 43 42 41 41 40 40 40 39 39 35

2.0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 15 28 42 51 55 54 51 47 44 43 42 41 41 40 40 39 39 36

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 14 26 38 50 54 52 47 44 43 42 41 40 40 40 39 36

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 13 29 43 53 51 47 44 43 42 41 40 40 39 37

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.1 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 7 12 14 18 21 23 26 30 32 33 37 38 41 42 46 48 53 49

.10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 9 12 15 19 22 25 29 32 32 35 39 41 42 45 48 53 49

.20 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 7 11 14 18 22 24 28 32 32 35 39 41 42 45 48 53 49

.30 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 8 12 15 20 23 27 31 31 34 39 40 41 45 48 53 49

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 1 5 9 13 18 22 25 30 31 33 37 39 41 44 47 53 49 0 0 0 0 0 0 0 0 0 0 0 0 2 6 10 15 20 24 29 31 32 36 39 41 44 47 53 53 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 11 16 21 26 30 31 34 38 40 43 46 53 53 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 6 11 17 23 28 31 32 35 39 42 45 53 53

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 8 17 23 28 31 32 35 40 43 49 52

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 9 17 23 28 31 32 38 42 48 52

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 10 18 24 28 31 36 40 47 52

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 11 18 24 28 33 39 45 52

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = IA

* * * TC = 0.1 HR * * *

SHEET 1 OF 10

5-19 A-1-59

5-20 A-1-60

Exhibit 5-IA, continued: Tabular hydrograph unit discharges (csm/in) for type IA rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

7.3

7.9

8.1

8.3

8.5

8.7

9.0

9.4

9.8

10.3

11.0

12.0

13.0

14.0

16.0

22.0

(HR) 7.0

7.6

8.0

8.2

8.4

8.6

8.8

9.2

9.6

10.0

10.6

11.5

12.5

13.5

15.0

18.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.2 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 27 34 46 124 143 153 153 127 103 87 76 68 67 63 57 51 47 45 44 42 40 39 36 33 33 32 32 31 30 29 27 21

.10 27 33 44 108 131 146 151 135 113 96 83 73 69 65 59 53 48 45 45 42 40 39 37 33 33 32 32 31 30 29 27 22

.20 26 29 38 67 95 119 137 146 139 122 105 90 79 69 63 57 52 47 45 44 41 39 37 34 33 32 32 31 30 29 27 22

.30 25 27 33 45 60 83 107 127 140 139 128 112 97 76 68 62 56 50 47 45 42 40 38 35 33 33 32 31 30 29 27 22

.40 24 27 32 43 .50 23 25 29 37 .75 20 24 27 33 1.0 16 20 24 27

54 73 96 117 132 137 131 118 104 81 70 63 57 52 48 45 43 40 38 36 33 33 32 32 30 29 41 50 65 86 106 124 132 131 123 98 79 69 62 56 51 46 44 41 39 37 34 33 32 32 30 29 36 41 50 63 80 97 112 121 123 111 93 78 68 61 55 48 45 42 39 37 34 33 32 32 30 30 29 31 33 37 43 52 65 81 96 120 120 102 85 73 64 55 49 44 41 39 36 34 33 32 31 30

27 22 27 22 27 22 28 23

1.5 12 15 19 22 23 24 26 27 28 30 33 37 44 63 88 107 111 102 89 72 60 50 44 41 38 36 34 33 32 30 28 23

2.0 7 10 12 16 17 18 19 20 22 23 24 25 27 30 38 52 71 91 105 101 86 66 52 45 41 39 36 34 32 31 29 24

2.5 4 6 9 11 12 13 14 15 16 17 19 20 21 23 26 30 38 50 68 92 101 88 65 51 44 41 38 36 33 31 29 25

3.0 2 3 5 7 7 8 9 10 11 12 13 14 15 17 19 22 24 28 33 49 72 97 89 68 53 45 41 39 34 32 30 25

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.2 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 26 45 64 76 74 65 59 55 53 52 51 49 46 44 44 43 43 42 42 41 40 40 40 40 40 39 39 38 33

.10 0 0 0 20 37 55 69 72 67 62 57 54 53 52 50 47 44 44 43 43 42 42 41 40 40 40 40 40 39 39 38 34

.20 0 0 0 5 15 30 47 61 68 68 64 59 56 53 52 49 46 44 44 43 43 42 42 41 40 40 40 40 39 39 38 34

.30 0 0 0 4 11 23 39 54 64 66 65 61 58 54 52 50 47 45 44 43 43 42 42 41 40 40 40 40 39 39 38 34

.40 0 0 0 3 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

8 18 32 47 58 64 64 62 59 55 52 50 48 45 44 43 43 42 42 41 40 40 40 40 40 39 2 6 14 26 40 52 60 63 62 58 54 52 50 47 45 44 43 42 42 41 40 40 40 40 40 39 1 3 7 14 24 35 45 53 57 59 56 54 51 49 47 44 43 43 42 41 41 40 40 40 40 39 0 0 1 4 8 15 25 35 44 56 58 56 54 51 49 46 44 43 42 42 41 40 40 40 40 39

38 34 38 34 38 34 39 35

1.5 0 0 0 0 0 0 0 0 0 1 2 5 9 23 38 50 55 56 54 51 47 44 43 42 42 41 40 40 40 39 39 35

2.0 0 0 0 0 0 0 0 0 0 0 0 1 1 6 15 27 40 49 54 54 51 47 44 43 42 41 41 40 40 40 39 36

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 14 25 36 49 53 51 47 44 43 42 41 41 40 40 39 36

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 6 13 28 42 52 51 47 44 43 42 41 40 40 39 37

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.2 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 5 10 13 16 19 23 25 29 32 33 36 39 41 42 46 48 50 49

.10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 10 14 17 21 24 28 31 32 35 40 41 42 45 48 50 49

.20 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 7 11 15 19 23 26 31 31 34 39 40 41 45 48 50 49

.30 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 8 12 17 21 25 30 31 33 37 39 41 44 47 50 50

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 2 5 9 15 19 23 28 31 32 35 39 41 44 47 50 50 0 0 0 0 0 0 0 0 0 0 0 0 0 3 6 12 17 22 27 31 32 34 39 40 43 46 50 50 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 9 14 20 25 30 31 33 37 39 42 46 50 50 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 9 16 22 27 31 32 35 38 42 45 49 50

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 8 17 23 28 31 32 35 40 43 49 50

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 9 17 23 28 31 32 38 42 48 50

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 9 16 22 27 30 35 40 46 50

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 9 17 23 27 33 38 45 50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = IA

* * * TC = 0.2 HR * * *

SHEET 2 OF 10

GaSWCC

GaSWCC

Exhibit 5-IA, continued: Tabular hydrograph unit discharges (csm/in) for type IA rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

7.3

7.9

8.1

8.3

8.5

8.7

9.0

9.4

9.8

10.3

11.0

12.0

13.0

14.0

16.0

22.0

(HR) 7.0

7.6

8.0

8.2

8.4

8.6

8.8

9.2

9.6

10.0

10.6

11.5

12.5

13.5

15.0

18.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.3 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 26 31 41 92 120 138 145 144 125 105 90 78 71 66 60 54 49 46 45 43 40 39 37 34 33 32 32 31 30 29 27 22

.10 26 30 39 80 106 128 139 142 131 113 98 85 76 68 62 56 51 47 45 43 41 39 37 34 33 32 32 31 30 29 27 22

.20 25 28 34 51 70 94 117 131 139 133 120 105 92 74 67 60 54 49 46 44 42 40 38 35 33 33 32 31 30 29 27 22

.30 24 26 31 40 47 62 84 106 123 133 133 124 112 87 73 65 59 53 49 45 43 40 39 36 33 33 32 32 30 29 27 22

.40 23 26 30 38 .50 21 25 28 34 .75 19 23 26 31 1.0 15 19 23 26

44 56 75 95 114 127 131 127 117 93 76 67 60 55 50 46 43 40 39 36 34 33 32 32 30 29 37 42 51 67 86 104 119 127 127 110 88 74 66 59 53 47 45 41 39 37 34 33 32 32 30 30 33 36 42 51 64 80 96 109 119 116 102 85 73 65 58 50 46 43 40 38 35 33 33 32 31 30 27 29 31 33 37 44 53 66 80 106 116 109 93 79 69 58 51 45 41 39 37 34 33 32 31 30

27 22 27 22 28 23 28 23

1.5 11 14 17 21 22 23 24 26 27 29 31 34 38 53 75 97 109 106 96 78 64 52 45 41 39 36 34 33 32 30 28 24

2.0 6 9 11 14 16 17 18 19 20 21 23 24 25 28 34 44 61 81 97 103 91 71 54 46 42 39 37 34 32 31 29 24

2.5 4 5 8 10 11 12 13 14 15 16 17 19 20 22 25 28 34 44 58 84 99 92 70 54 46 41 39 36 33 32 29 25

3.0 2 3 5 7 7 8 9 10 11 12 13 14 15 17 19 22 24 28 33 49 71 96 89 68 53 45 41 39 34 32 30 25

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.3 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 13 28 45 63 69 69 65 60 55 53 53 51 48 45 44 43 43 42 42 42 40 40 40 40 40 39 39 38 34

.10 0 0 0 9 21 37 54 64 67 65 62 57 54 53 51 49 46 44 43 43 42 42 42 41 40 40 40 40 40 39 38 34

.20 0 0 0 7 17 30 46 58 64 65 63 59 56 53 52 49 46 44 44 43 42 42 42 41 40 40 40 40 40 39 38 34

.30 0 0 0 1 5 13 25 39 52 60 63 63 60 55 53 51 49 46 44 43 43 42 42 41 40 40 40 40 40 39 38 34

.40 0 0 0 1 .50 0 0 0 1 .75 0 0 0 0 1.0 0 0 0 0

4 10 20 33 45 55 61 62 61 56 54 52 49 46 45 43 43 42 42 41 40 40 40 40 40 39 3 7 15 27 39 50 57 60 61 57 54 52 50 47 45 44 43 42 42 41 40 40 40 40 40 39 1 3 8 15 24 34 43 51 55 58 56 54 52 49 47 44 43 43 42 41 41 40 40 40 40 39 0 0 0 2 4 9 16 25 34 49 56 57 55 53 50 47 44 43 42 42 41 40 40 40 40 39

38 34 38 34 38 34 39 35

1.5 0 0 0 0 0 0 0 0 0 1 3 5 10 23 37 49 54 55 54 51 47 44 43 42 42 41 40 40 40 39 39 35

2.0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 10 21 33 44 51 54 52 48 44 43 42 41 41 40 40 40 39 36

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 10 19 30 45 53 53 48 44 43 42 41 41 40 40 39 37

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 9 23 37 50 52 47 44 43 42 41 40 40 39 37

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC =0.3 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 7 11 14 18 22 24 28 32 32 35 40 41 42 45 48 48 48

.10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 8 12 15 20 23 27 31 31 34 39 40 41 45 48 48 48

.20 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 9 13 18 21 25 30 31 33 37 39 41 44 47 48 48

.30 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 8 12 17 21 25 30 31 33 37 39 41 44 47 48 48

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 2 5 9 14 19 23 28 31 32 35 39 41 44 47 48 48 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 10 15 21 26 30 31 33 38 40 43 46 48 48 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 7 13 19 24 29 31 33 36 39 42 46 48 48 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 9 16 22 27 31 32 35 38 42 45 48 48

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 8 16 23 27 31 32 35 40 43 48 48

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 8 16 22 27 30 32 38 42 47 48

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 9 16 22 27 30 35 40 46 48

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 9 17 23 27 33 38 45 48

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = IA

* * * TC = 0.3 HR * * *

SHEET 3 OF 10

5-21 A-1-61

5-22 A-1-62

Exhibit 5-IA, continued: Tabular hydrograph unit discharges (csm/in) for type IA rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

7.3

7.9

8.1

8.3

8.5

8.7

9.0

9.4

9.8

10.3

11.0

12.0

13.0

14.0

16.0

22.0

(HR) 7.0

7.6

8.0

8.2

8.4

8.6

8.8

9.2

9.6

10.0

10.6

11.5

12.5

13.5

15.0

18.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/F = 0.10

* * * TC = 0.4 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 26 29 37 67 93 117 134 137 136 121 105 91 81 70 64 58 52 48 46 44 41 40 37 34 33 33 32 31 30 29 27 22

.10 25 29 36 60 82 105 124 133 135 126 112 98 87 73 66 59 53 49 46 44 41 40 38 34 33 33 32 31 30 29 27 22

.20 24 27 32 43 55 73 94 114 127 132 128 117 104 83 71 64 58 52 48 45 43 40 38 35 33 33 32 32 30 29 27 22

.30 24 26 31 41 50 65 85 104 119 128 128 121 110 88 74 66 59 54 49 46 43 40 39 35 34 33 32 32 30 29 27 22

.40 22 25 28 35 .50 20 23 26 31 .75 16 20 24 27 1.0 14 18 22 25

39 46 59 76 95 111 122 126 122 104 85 72 64 58 52 47 44 41 39 37 34 33 32 32 30 29 34 37 43 54 69 86 103 116 123 117 98 82 71 63 56 49 46 42 40 38 34 33 33 32 30 30 29 31 33 37 43 53 65 80 94 116 116 101 86 74 65 56 49 44 41 39 36 34 33 32 31 30 26 27 29 31 34 38 45 54 67 93 111 113 101 87 75 62 53 47 42 40 37 34 33 33 31 30

27 22 27 22 28 23 28 23

1.5 10 13 16 20 21 22 23 24 26 27 29 31 34 45 64 86 102 107 101 84 69 55 46 42 39 37 34 33 32 30 28 24

2.0 6 8 11 13 14 16 17 18 19 20 21 23 24 27 31 39 52 71 88 102 96 76 57 47 42 40 37 35 33 31 29 24

2.5 3 5 7 9 10 11 12 13 14 15 16 17 18 21 23 26 31 38 51 75 94 98 74 57 47 42 39 37 33 32 30 25

3.0 1 2 4 6 7 7 8 9 10 11 12 13 14 16 18 20 23 26 30 43 64 89 95 72 56 47 42 39 34 33 30 25

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.4 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 6 15 29 46 60 65 65 63 59 56 53 52 49 47 44 44 43 42 42 42 41 40 40 40 40 40 39 38 34

.10 0 0 0 4 12 23 38 53 61 63 63 60 57 54 53 50 47 45 44 43 42 42 42 41 40 40 40 40 40 39 38 34

.20 0 0 0 3 9 19 32 46 56 61 62 61 59 55 53 51 48 45 44 43 43 42 42 41 40 40 40 40 40 39 38 34

.30 0 0 0 2 7 15 26 39 50 57 61 61 59 56 53 51 49 46 44 44 43 42 42 41 40 40 40 40 40 39 38 34

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

2 5 11 21 33 44 53 58 60 58 55 53 51 48 45 44 43 42 42 41 40 40 40 40 40 39 38 34 1 4 9 17 28 39 48 55 59 59 56 53 51 49 46 44 43 42 42 41 40 40 40 40 40 39 38 34 0 2 4 9 16 25 34 43 49 57 57 55 53 50 48 45 44 43 42 41 41 40 40 40 40 39 39 35 0 0 1 2 5 10 17 25 34 48 55 56 55 53 50 47 45 43 42 42 41 40 40 40 40 39 39 35

1.5 0 0 0 0 0 0 0 0 0 0 1 3 6 16 30 43 51 55 55 52 49 45 43 42 42 41 40 40 40 40 39 36

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 15 27 39 47 53 53 49 45 43 42 42 41 40 40 40 39 36

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 7 14 25 40 50 52 49 45 43 42 41 41 40 40 39 37

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 7 18 32 47 52 48 45 43 42 41 40 40 39 37

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.4 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 9 13 16 20 23 27 31 32 34 39 40 42 45 47 47 47

.10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 10 13 18 22 26 30 31 33 38 39 41 45 47 47 47

.20 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 7 11 16 20 24 29 31 33 36 39 41 44 47 47 47

.30 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 8 13 18 23 28 31 32 35 39 41 43 47 47 47

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 11 16 21 26 30 32 34 38 40 43 46 47 47 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 8 13 19 25 29 31 33 37 39 42 46 47 47 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 11 17 23 28 31 32 35 39 42 45 47 47 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 12 20 25 29 31 33 37 41 44 47 47

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 13 20 26 30 31 34 40 43 47 47

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 6 14 21 26 30 32 37 41 47 47

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 7 15 21 26 30 34 40 46 47

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 8 15 22 27 32 38 45 47

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = IA

* * * TC = 0.4 HR * * *

SHEET 4 OF 10

GaSWCC

GaSWCC

Exhibit 5-IA, continued: Tabular hydrograph unit discharges (csm/in) for type IA rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

7.3

7.9

8.1

8.3

8.5

8.7

9.0

9.4

9.8

10.3

11.0

12.0

13.0

14.0

16.0

22.0

(HR) 7.0

7.6

8.0

8.2

8.4

8.6

8.8

9.2

9.6

10.0

10.6

11.5

12.5

13.5

15.0

18.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.5 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 25 28 34 53 72 94 115 129 130 129 117 104 92 76 68 61 55 50 47 44 42 40 38 34 33 33 32 31 30 29 27 22

.10 24 27 33 49 64 84 105 121 127 128 121 109 98 80 70 63 57 51 48 45 42 40 38 34 33 33 32 32 30 29 27 22

.20 23 26 30 39 46 58 75 95 112 122 126 123 114 93 78 69 61 55 50 46 44 41 39 36 34 33 32 32 30 29 27 22

.30 21 24 27 34 37 43 53 68 86 103 116 123 123 108 89 76 67 60 54 48 45 42 39 37 34 33 33 32 30 30 27 22

.40 20 24 27 32 .50 18 22 25 29 .75 15 19 23 26 1.0 13 16 20 24

35 40 49 61 78 95 109 118 121 111 93 79 69 62 55 49 45 42 40 37 34 33 33 32 30 30 31 34 38 45 56 70 87 101 113 118 106 89 77 67 60 52 47 43 40 38 35 33 33 32 31 30 27 29 31 34 38 45 54 67 80 104 112 106 93 80 70 59 51 46 41 39 36 34 33 33 31 30 25 26 27 29 31 34 39 46 56 80 102 110 105 93 81 66 56 48 43 40 38 35 33 33 31 30

27 22 28 23 28 23 28 23

1.5 9 12 15 18 20 21 22 23 24 26 27 29 31 39 55 75 94 104 103 89 74 58 48 43 40 37 35 33 32 31 29 24

2.0 5 7 10 12 13 14 15 17 18 19 20 21 23 25 29 35 45 62 79 100 100 81 61 49 43 40 38 35 33 31 29 25

2.5 3 4 6 8 9 10 11 12 13 14 15 16 17 20 22 25 28 34 45 67 88 96 79 60 49 43 40 37 33 32 30 25

3.0 1 2 3 5 6 7 7 8 9 10 11 12 13 15 17 19 21 24 28 38 56 63 93 77 59 48 43 40 35 33 30 26

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.5 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 2 8 18 31 46 57 61 61 61 58 54 53 51 46 45 44 44 43 42 42 41 40 40 40 40 40 39 38 34

.10 0 0 0 2 6 14 25 39 51 58 60 61 59 55 53 51 49 46 44 44 43 42 42 41 40 40 40 40 40 39 38 34

.20 0 0 0 0 1 4 11 21 33 45 54 58 60 58 55 53 51 48 46 44 43 42 42 41 40 40 40 40 40 39 38 34

.30 0 0 0 0 1 3 8 16 27 39 49 55 59 59 55 53 51 49 46 44 43 42 42 41 40 40 40 40 40 39 39 34

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

1 2 6 13 23 34 44 51 56 58 56 54 52 49 47 44 43 42 42 41 40 40 40 40 40 39 39 34 0 0 2 5 10 18 29 39 47 56 57 55 53 51 49 45 44 43 42 41 41 40 40 40 40 39 39 35 0 0 1 2 5 10 17 25 34 48 54 56 55 53 50 47 45 43 42 42 41 40 40 40 40 39 39 35 0 0 0 0 0 1 3 6 11 26 41 51 55 55 54 50 47 44 43 42 41 41 40 40 40 40 39 35

1.5 0 0 0 0 0 0 0 0 0 0 0 0 1 4 11 23 36 47 52 54 52 46 44 43 42 41 40 40 40 40 39 36

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 7 16 27 38 49 53 51 47 44 42 42 41 40 40 40 39 36

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 7 15 30 43 52 50 46 44 42 42 41 40 40 39 37

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 10 23 40 51 50 46 44 42 42 40 40 39 37

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.5 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 7 11 14 19 22 26 30 31 34 38 40 41 45 46 46 46

.10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 8 12 17 21 25 29 31 33 37 39 41 44 46 46 46

.20 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 9 14 19 23 28 31 32 35 39 41 43 46 46 46

.30 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 6 12 17 22 27 31 32 34 38 40 43 46 46 46

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 1 16 21 26 30 32 34 38 40 43 46 46 46 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 8 13 19 25 29 31 33 37 39 42 46 46 46 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 11 17 23 28 31 32 35 39 42 45 46 46 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 11 18 24 29 31 33 36 41 44 46 46

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 11 19 24 29 31 33 39 42 46 46

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 1 5 12 19 25 29 31 37 41 46 46

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 6 13 20 25 29 34 39 45 46

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 7 14 20 26 32 37 44 46

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = IA

* * * TC = 0.5 HR * * *

SHEET 5 OF 10

5-23 A-1-63

5-24 A-1-64

Exhibit 5-IA, continued: Tabular hydrograph unit discharges (csm/in) for type IA rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

7.3

7.9

8.1

8.3

8.5

8.7

9.0

9.4

9.8

10.3

11.0

12.0

13.0

14.0

16.0

22.0

(HR) 7.0

7.6

8.0

8.2

8.4

8.6

8.8

9.2

9.6

10.0

10.6

11.5

12.5

13.5

15.0

18.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.75 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 22 25 29 38 45 56 71 87 103 114 117 117 111 95 81 72 65 58 53 48 45 41 39 36 33 33 33 32 30 29 27 22

.10 21 25 28 36 42 51 64 79 95 108 114 116 113 99 85 74 66 60 54 48 45 42 39 37 34 33 33 32 30 30 27 22

.20 19 23 26 32 35 39 47 58 72 87 101 110 114 109 95 82 72 65 58 51 47 43 40 38 34 33 33 32 31 30 27 23

.30 19 22 26 31 33 37 44 54 66 80 94 104 112 110 98 85 75 67 60 52 47 43 40 38 34 33 33 32 31 30 28 23

.40 17 21 24 28 .50 16 20 23 27 .75 15 18 22 25 1.0 12 15 18 22

30 32 36 41 49 61 74 87 99 111 106 94 82 73 65 56 49 45 41 39 35 33 33 33 31 30 29 31 34 39 46 56 68 81 93 109 107 97 85 75 67 57 50 45 41 39 36 33 33 33 31 30 27 28 31 34 38 45 54 64 75 95 104 102 93 83 74 62 54 47 42 40 37 34 33 33 31 30 23 24 25 27 29 31 34 39 46 65 85 100 103 98 88 74 62 52 45 41 39 35 33 33 32 30

28 23 28 23 28 23 28 23

1.5 7 10 12 15 17 18 19 20 21 22 24 25 26 31 39 53 71 87 99 99 85 68 53 46 41 39 36 34 33 31 29 24

2.0 4 6 8 11 12 13 14 15 16 17 18 19 21 23 26 31 39 51 67 88 95 86 67 53 45 41 38 36 33 32 29 25

2.5 2 3 5 7 8 9 10 11 11 12 13 14 16 18 20 23 26 30 38 56 77 93 84 66 52 45 41 38 34 33 30 25

3.0 0 1 2 4 4 5 6 6 7 8 8 9 10 12 14 16 18 21 24 30 42 67 90 84 68 54 46 42 36 33 30 26

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.75 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 2 4 10 19 29 39 48 53 56 56 54 53 51 49 46 44 44 42 42 40 40 40 40 40 40 39 39 34

.10 0 0 0 0 1 3 8 15 24 34 43 50 54 56 54 53 52 49 47 45 44 42 42 41 40 40 40 40 40 39 39 34

.20 0 0 0 0 0 1 2 6 12 20 30 39 46 54 55 54 53 51 49 46 44 43 42 41 40 40 40 40 40 39 39 35

.30 0 0 0 0 0 1 2 5 10 17 25 34 42 52 55 54 53 51 49 46 44 43 42 42 40 40 40 40 40 39 39 35

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 1 4 8 14 21 30 38 50 55 55 53 52 50 47 45 43 42 42 40 40 40 40 40 39 39 35 0 0 1 3 6 11 18 26 34 47 53 54 54 52 50 47 45 43 42 42 40 40 40 40 40 39 39 35 0 0 0 1 3 6 10 16 23 37 47 52 53 53 52 49 46 44 42 42 41 40 40 40 40 40 39 35 0 0 0 0 0 1 2 4 7 17 30 42 50 53 53 51 49 45 43 42 41 40 40 40 40 40 39 36

1.5 0 0 0 0 0 0 0 0 0 0 0 0 1 4 11 21 33 43 49 52 51 48 45 43 42 41 40 40 40 40 39 36

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 11 20 30 43 50 51 48 45 43 42 41 40 40 40 39 37

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 10 23 36 48 51 47 44 43 42 41 40 40 39 37

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 7 17 34 48 50 47 44 43 42 40 40 39 38

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.75 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 6 10 15 19 23 28 31 32 36 39 41 44 44 44 44

.10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 7 12 17 22 27 30 32 34 38 40 43 44 44 44

.20 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 5 10 15 20 25 30 31 33 37 39 43 44 44 44

.30 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 7 12 18 24 29 31 33 36 39 42 44 44 44

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 10 16 22 27 30 32 35 38 42 44 44 44 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 7 14 21 26 30 31 34 38 41 44 44 44 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 11 19 24 29 31 33 36 41 44 44 44 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 8 16 22 27 30 32 35 40 43 44 44

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 9 16 23 27 30 32 38 42 44 44

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 10 17 23 28 30 36 40 44 44

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 11 18 23 28 33 39 44 44

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 10 17 23 30 36 43 44

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = IA

* * * TC = 0.75 HR * * *

SHEET 6 OF 10

GaSWCC

GaSWCC

Exhibit 5-IA, continued: Tabular hydrograph unit discharges (csm/in) for type IA rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

7.3

7.9

8.1

8.3

8.5

8.7

9.0

9.4

9.8

10.3

11.0

12.0

13.0

14.0

16.0

22.0

(HR) 7.0

7.6

8.0

8.2

8.4

8.6

8.8

9.2

9.6

10.0

10.6

11.5

12.5

13.5

15.0

18.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 1.0 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 19 23 26 33 37 43 52 63 76 88 97 104 108 102 91 81 72 65 59 52 48 43 40 38 34 33 33 32 31 30 28 23

.10 19 22 26 32 35 41 48 58 70 82 92 100 105 103 94 83 75 67 61 53 48 44 40 38 35 33 33 32 31 30 28 23

.20 17 21 24 28 30 34 38 45 54 65 76 87 96 104 100 91 81 73 66 57 51 45 41 39 36 33 33 33 31 30 28 23

.30 16 20 23 27 29 32 36 42 50 60 71 81 91 103 101 93 84 75 67 58 52 46 42 39 36 34 33 33 31 30 28 23

.40 15 18 22 25 .50 14 18 21 25 .75 13 16 19 23 1.0 10 13 16 19

27 29 31 35 40 46 55 65 76 94 102 99 91 81 73 63 55 48 43 40 37 34 33 33 31 30 26 28 30 33 37 43 51 61 71 90 101 101 93 84 75 64 56 49 43 40 37 34 33 33 31 30 24 25 27 29 32 37 42 49 58 76 91 98 96 89 81 70 60 51 45 41 38 35 34 33 32 30 20 22 23 24 26 27 30 33 37 50 67 83 94 97 93 81 70 58 48 43 40 37 34 33 32 31

28 23 28 23 28 23 29 24

1.5 6 8 10 13 14 15 16 18 19 20 21 22 24 27 33 42 56 71 84 93 89 75 59 49 44 40 37 35 33 31 29 24

2.0 3 5 7 9 10 11 12 13 14 15 16 17 18 21 23 27 32 41 53 74 88 91 74 59 49 43 40 37 34 32 30 25

2.5 1 2 4 6 7 7 8 9 10 11 11 12 13 16 18 20 23 26 32 45 64 84 89 72 58 48 43 40 34 33 30 26

3.0 0 1 2 3 3 4 4 5 6 6 7 8 9 10 12 14 16 18 21 26 35 55 81 87 73 59 50 44 37 34 31 26

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 1.0 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 1 2 5 10 16 23 31 38 44 51 53 52 52 50 48 46 44 43 42 41 40 40 40 40 40 40 39 35

.10 0 0 0 0 0 1 2 4 8 13 20 27 35 46 51 53 52 51 50 47 45 44 42 42 40 40 40 40 40 40 39 35

.20 0 0 0 0 0 0 1 3 6 11 17 24 31 43 50 52 52 51 50 47 45 44 42 42 40 40 40 40 40 40 39 35

.30 0 0 0 0 0 0 1 2 5 9 14 21 28 40 48 52 52 52 50 48 46 44 43 42 40 40 40 40 40 40 39 35

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 1 2 4 7 12 18 31 42 49 52 52 51 49 47 45 43 42 41 40 40 40 40 40 39 35 0 0 0 1 1 3 6 10 15 28 39 47 51 52 51 49 47 45 43 42 41 40 40 40 40 40 39 35 0 0 0 0 1 1 3 6 9 19 31 41 47 50 51 50 48 46 43 42 41 40 40 40 40 40 39 36 0 0 0 0 0 0 0 1 2 6 14 25 36 44 49 51 50 47 45 43 42 41 40 40 40 40 39 36

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 6 13 23 33 44 49 50 47 44 43 42 41 40 40 40 39 37

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 6 13 25 38 48 50 47 44 43 42 41 40 40 39 37

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 9 19 36 48 49 47 44 43 42 40 40 39 38

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 18 37 47 49 46 44 43 41 40 40 38

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 1.0 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 4 7 11 16 21 26 30 32 34 38 40 43 43 43 43

.10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 5 9 14 19 25 29 31 33 37 39 42 43 43 43

.20 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 7 11 17 23 28 30 32 36 39 42 43 43 43

.30 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 9 15 21 27 30 32 35 38 41 43 43 43

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 7 13 20 25 29 31 34 37 41 43 43 43

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 11 18 24 28 31 33 36 41 43 43 43

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 8 16 22 27 30 32 35 40 43 43 43

000000000

0 0 0 0 0 0 2 6 13 20 25 29 31 34 39 42 43 43

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 7 14 20 25 29 31 37 41 43 43

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 7 14 20 26 29 34 39 43 43

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 8 15 21 26 32 37 43 43

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 8 14 20 29 34 42 43

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = IA

* * * TC = 1.0 HR * * *

SHEET 7 OF 10

5-25 A-1-65

5-26 A-1-66

Exhibit 5-IA, continued: Tabular hydrograph unit discharges (csm/in) for type IA rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

7.3

7.9

8.1

8.3

8.5

8.7

9.0

9.4

9.8

10.3

11.0

12.0

13.0

14.0

16.0

22.0

(HR) 7.0

7.6

8.0

8.2

8.4

8.6

8.8

9.2

9.6

10.0

10.6

11.5

12.5

13.5

15.0

18.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 1.25 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 17 21 24 29 33 37 43 52 61 71 81 89 95 100 94 86 78 71 64 57 51 46 42 39 35 34 33 33 31 30 28 23

.10 16 19 23 27 29 31 35 41 48 57 66 76 85 96 99 92 84 76 69 60 54 47 43 40 36 34 34 33 31 30 28 23

.20 15 19 22 26 28 30 33 38 45 53 62 71 80 93 97 93 86 78 71 62 55 48 43 40 37 34 34 33 31 30 28 23

.30 14 17 20 24 25 27 29 32 36 42 49 58 67 84 95 96 91 84 76 66 58 50 44 41 38 35 34 33 31 30 28 23

.40 13 16 20 23 .50 12 15 18 21 .75 10 13 16 20 1.0 8 10 13 16

25 26 28 31 34 39 46 54 62 80 92 96 93 86 78 68 59 51 45 41 38 35 34 33 31 30 23 24 25 27 29 33 37 43 50 67 83 93 95 91 84 73 63 54 46 42 39 36 34 33 32 30 21 22 23 25 27 29 32 36 42 55 71 84 93 93 88 78 68 57 49 43 40 37 34 34 32 31 17 19 20 21 22 23 25 27 29 37 49 63 78 88 92 88 78 65 53 46 42 39 36 34 33 31

28 23 28 23 28 24 29 24

1.5 5 7 9 12 13 14 15 16 17 18 19 20 22 25 29 36 47 60 73 87 89 79 64 53 46 42 38 36 33 32 29 25

2.0 2 4 6 8 9 10 10 11 12 13 14 15 16 19 21 24 29 36 45 64 80 87 77 63 52 46 41 38 34 32 30 25

2.5 1 2 3 4 5 6 6 7 8 8 9 10 11 13 15 17 19 22 26 35 49 72 85 78 65 53 46 42 36 33 30 26

3.0 0 1 1 2 3 3 4 4 5 5 6 7 7 9 11 12 14 17 19 23 31 47 73 84 76 63 53 46 38 34 31 26

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 1.25 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 1 3 6 10 15 22 28 34 43 48 51 51 51 49 47 45 44 43 42 40 40 40 40 40 40 39 35

.10 0 0 0 0 0 0 1 2 5 8 13 19 25 36 45 49 51 50 50 48 46 44 43 42 40 40 40 40 40 40 39 35

.20 0 0 0 0 0 0 1 2 4 7 11 16 22 34 43 48 50 50 50 48 46 44 43 42 41 40 40 40 40 40 39 35

.30 0 0 0 0 0 0 1 1 3 5 9 14 19 31 40 46 49 50 50 48 46 45 43 42 41 40 40 40 40 40 39 35

.40 0 0 0 0 .50 0 0 0 0 . 75 0 0 0 0 1.0 0 0 0 0

0 0 0 1 2 4 8 12 17 28 38 45 49 50 50 49 47 45 43 42 41 40 40 40 40 40 39 35 0 0 0 1 2 4 6 10 14 25 36 43 48 50 50 49 47 45 43 42 41 40 40 40 40 40 39 35 0 0 0 0 0 1 2 3 6 13 23 33 41 46 49 50 48 46 44 43 42 40 40 40 40 40 39 36 0 0 0 0 0 0 0 1 2 6 14 23 32 40 46 49 49 47 45 43 42 41 40 40 40 40 39 36

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 6 13 21 30 41 47 49 47 45 43 42 41 40 40 40 39 37

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 6 12 23 35 45 48 47 45 43 42 41 40 40 40 37

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 8 18 33 45 48 46 44 43 42 40 40 40 38

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 17 34 45 48 46 44 43 41 40 40 38

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 1.25 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 5 9 14 19 24 28 31 33 37 39 42 42 42 42

.10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 7 11 17 23 27 30 32 36 38 42 42 42 42

.20 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 5 9 15 21 26 29 32 35 38 41 42 42 42

.30 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 7 13 19 25 29 31 34 37 41 42 42 42

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 11 17 23 28 30 33 36 40 42 42 42 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 8 15 22 26 30 32 35 40 42 42 42 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 7 13 20 25 29 31 34 39 42 42 42 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 11 17 23 27 30 33 38 42 42 42

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 11 18 23 28 30 36 40 42 42

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 6 12 18 24 28 33 39 42 42

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 13 19 24 31 37 42 42

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 12 18 28 33 42 42

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = IA

* * * TC = 1.25 HR * * *

SHEET 8 OF 10

GaSWCC

GaSWCC

Exhibit 5-IA, continued: Tabular hydrograph unit discharges (csm/in) for type IA rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

7.3

7.9

8.1

8.3

8.5

8.7

9.0

9.4

9.8

10.3

11.0

12.0

13.0

14.0

16.0

22.0

(HR) 7.0

7.6

8.0

8.2

8.4

8.6

8.8

9.2

9.6

10.0

10.6

11.5

12.5

13.5

15.0

18.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 1.5 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 15 19 22 27 29 32 37 42 49 57 65 73 80 89 94 89 83 76 70 62 55 49 44 40 37 35 34 33 31 30 28 23

.10 14 17 20 24 26 28 31 35 40 46 53 61 69 82 90 92 87 81 74 65 58 51 45 41 38 35 34 33 31 30 28 23

.20 13 16 20 23 25 27 29 33 37 43 50 57 65 79 88 91 88 82 76 67 59 52 46 42 38 35 34 33 32 30 28 23

.30 12 15 18 22 23 24 26 28 31 35 41 47 54 69 81 89 90 86 81 71 63 54 47 43 39 36 34 34 32 30 28 24

.40 11 14 18 21 .50 10 13 16 19 .75 9 11 14 18 1.0 7 9 11 14

22 24 25 27 30 34 38 44 51 65 78 87 90 87 82 73 64 55 48 43 40 36 34 34 32 30 20 22 23 24 26 29 32 36 41 54 69 81 88 89 86 77 68 58 50 44 41 37 35 34 32 31 19 20 21 22 24 26 28 31 35 46 58 71 82 88 88 81 73 62 52 46 42 38 35 34 32 31 15 16 18 19 20 21 22 24 26 32 40 52 65 76 84 87 81 70 58 49 44 40 37 35 33 31

28 24 29 24 29 24 29 24

1.5 4 6 8 10 11 12 13 14 15 16 17 18 19 22 26 31 39 50 62 77 85 81 69 57 49 44 40 37 34 32 30 25

2.0 2 3 5 7 7 8 9 10 11 12 12 13 14 17 19 22 25 31 38 53 69 83 80 68 56 48 43 40 35 33 30 25

2.5 1 1 2 3 4 5 5 6 6 7 8 9 9 11 13 15 17 20 23 30 41 61 82 82 69 58 49 44 37 34 31 26

3.0 0 0 1 2 2 2 3 3 4 4 5 5 6 8 9 11 13 15 17 21 27 40 63 80 78 68 57 49 40 35 31 27

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 1.5 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 1 2 4 6 10 14 19 24 34 41 46 48 49 48 47 46 44 43 42 41 40 40 40 40 40 39 35

.10 0 0 0 0 0 0 1 1 3 5 8 12 17 27 36 42 46 48 49 48 46 45 43 42 41 40 40 40 40 40 39 36

.20 0 0 0 0 0 0 0 1 2 4 7 10 15 24 33 41 45 48 49 48 47 45 43 43 41 40 40 40 40 40 39 36

.30 0 0 0 0 0 0 0 1 2 3 6 9 13 22 31 39 44 47 48 48 47 45 44 43 41 40 40 40 40 40 39 36

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 1 1 3 5 7 15 24 33 40 45 47 48 47 46 44 43 42 40 40 40 40 40 39 36 0 0 0 0 0 1 2 4 6 13 22 31 38 44 47 48 48 46 44 43 42 40 40 40 40 40 39 36 0 0 0 0 0 1 1 2 4 9 16 24 33 39 44 47 48 47 45 43 42 41 40 40 40 40 39 36 0 0 0 0 0 0 0 0 1 2 6 12 20 29 36 44 47 48 46 44 43 42 40 40 40 40 40 36

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 6 12 19 30 39 46 47 46 44 43 42 40 40 40 40 37

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 4 8 17 28 40 46 47 45 44 42 41 40 40 40 37

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 6 13 26 40 47 47 45 43 42 40 40 40 38

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 12 28 41 46 46 45 43 41 40 40 38

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 1.5 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 3 7 11 16 22 27 30 32 35 38 42 42 42 42

.10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 4 7 13 19 24 28 31 34 37 41 42 42 42

.20 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 7 12 19 24 28 31 33 36 41 42 42 42

.30 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 6 12 18 23 28 30 33 36 40 42 42 42

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 6 11 17 23 27 30 33 36 40 42 42 42 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 5 10 17 22 27 30 32 36 40 41 41 41 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 5 10 16 22 26 29 32 35 40 41 41 41 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 11 17 23 27 30 33 38 41 41 41

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 12 18 23 27 30 36 40 41 41

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 12 18 24 28 33 39 41 41

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 7 13 19 24 31 36 41 41

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 7 13 19 28 34 41 41

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = IA

* * * TC = 1.5 HR * * *

SHEET 9 OF 10

5-27 A-1-67

5-28 A-1-68

Exhibit 5-IA, continued: Tabular hydrograph unit discharges (csm/in) for type IA rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

7.3

7.9

8.1

8.3

8.5

8.7

9.0

9.4

9.8

10.3

11.0

12.0

13.0

14.0

16.0

22.0

(HR) 7.0

7.6

8.0

8.2

8.4

8.6

8.8

9.2

9.6

10.0

10.6

11.5

12.5

13.5

15.0

18.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 2.0

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 12 15 18 22 24 26 28 32 36 41 46 52 58 68 76 80 84 79 76 68 62 55 48 44 40 37 35 34 32 31 28 24

.10 11 13 16 20 21 23 25 27 30 34 38 43 49 60 70 77 83 83 78 72 65 57 50 45 41 38 36 34 32 31 29 24

.20 9 12 15 18 19 21 22 24 26 29 32 36 41 52 63 72 78 82 81 75 68 60 52 46 42 39 36 35 32 31 29 24

.30 9 12 14 18 19 20 21 23 25 28 31 34 39 49 60 70 77 81 81 76 70 61 53 47 43 39 36 35 33 31 29 24

.40 9 11 14 17 18 19 21 22 24 26 29 33 37 47 57 67 75 80 81 77 71 62 53 47 43 39 37 35 33 31 29 24 .50 7 10 12 15 17 18 19 20 21 23 25 28 31 39 49 60 69 76 81 79 74 65 56 49 44 40 37 35 33 31 29 24 .75 6 9 11 14 15 16 17 18 20 21 23 25 27 34 42 52 62 70 76 79 76 68 59 51 46 41 38 36 33 31 29 24 1.0 5 6 9 11 12 13 14 15 16 17 18 20 21 25 30 38 47 57 66 76 79 75 64 55 49 44 40 37 34 32 29 25

1.5 3 4 6 8 8 9 10 11 12 13 14 15 16 18 21 24 30 37 45 59 71 78 73 63 55 48 43 40 35 33 30 25

2.0 1 2 3 4 5 5 6 7 7 8 9 10 10 12 14 16 19 22 26 36 48 65 77 73 64 56 49 44 37 34 31 26

2.5 0 1 1 2 3 3 4 4 5 5 6 6 7 8 10 12 14 16 18 23 31 46 66 76 72 63 55 48 40 35 31 27

3.0 0 0 1 1 1 2 2 2 3 3 3 4 4 5 7 8 10 11 13 17 21 30 49 67 75 71 63 54 43 37 32 27

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 2.0 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 1 2 3 5 7 10 13 20 27 34 39 42 44 47 45 45 44 43 42 40 40 40 40 40 39 36

.10 0 0 0 0 0 0 0 1 1 2 4 6 8 15 22 29 35 40 43 45 46 45 44 43 42 41 40 40 40 40 40 36

.20 0 0 0 0 0 0 0 0 1 1 2 3 5 10 17 24 31 36 41 44 46 45 44 43 42 41 40 40 40 40 40 36

.30 0 0 0 0 0 0 0 0 0 1 2 3 4 9 15 22 29 35 39 44 46 45 44 43 42 41 40 40 40 40 40 36

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 1 1 2 4 8 14 20 27 33 38 43 46 46 44 43 42 41 40 40 40 40 40 36 0 0 0 0 0 0 1 1 2 5 9 15 22 29 35 41 44 45 45 44 43 42 40 40 40 40 40 36 0 0 0 0 0 0 0 1 1 3 6 11 17 24 30 38 42 45 45 44 43 42 41 40 40 40 40 37 0 0 0 0 0 0 0 0 0 1 2 5 9 14 21 30 38 43 45 44 44 43 41 40 40 40 40 37

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 4 8 16 25 36 43 45 44 43 42 41 40 40 40 38

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 6 12 24 36 43 45 44 43 42 40 40 40 38

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 12 25 37 43 45 44 43 41 40 40 38

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 13 26 37 43 44 44 42 40 40 39

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 2.0 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 4 7 12 18 23 27 30 33 36 40 40 40 40

.10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 5 10 16 21 26 29 32 35 40 40 40 40

.20 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 4 8 14 20 25 28 31 34 39 40 40 40

.30 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 6 12 18 23 27 30 33 38 40 40 40

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 5 11 16 22 26 29 32 38 40 40 40 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 9 15 20 25 28 31 37 40 40 40 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 7 13 19 24 27 30 36 40 40 40 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 8 14 20 24 28 34 39 40 40

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 10 16 21 25 32 37 40 40

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 11 16 21 29 35 40 40

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 11 17 26 32 40 40

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 11 21 29 39 40

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = IA

* * * TC = 2.0 HR * * *

SHEET 10 OF 10

GaSWCC

GaSWCC

Exhibit 5-II: Tabular hydrograph unit discharges (csm/in) for type II rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.1 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 24 34 53 334 647 1010 628 217 147 123 104 86 76 66 57 51 46 42 38 34 32 29 26 23 21 20 19 18 15 13 12 0

.10 21 29 43 134 267 520 847 701 378 224 157 122 98 75 64 56 50 45 41 36 33 30 27 24 21 20 19 18 16 13 12 0

.20 18 25 35 61 110 215 418 704 702 486 312 209 151 94 73 62 54 49 44 38 34 31 28 25 22 21 19 18 16 14 12 0

.30 17 23 33 56 92 174 337 582 662 545 389 269 190 109 79 65 56 50 45 39 35 32 29 25 22 21 20 18 16 14 12 0

.40 15 20 28 41 51 78 142 272 478 601 563 447 328 172 104 76 63 55 49 42 37 33 29 26 23 21 20 19 17 14 12 0

.50 14 19 26 39 47 68 117 220 392 531 553 482 380 209 121 84 67 57 51 43 38 33 30 27 23 21 20 19 17 14 12 0

.75 12 15 21 29 33 38 49 73 126 224 343 432 464 385 252 156 103 76 62 50 43 36 31 28 25 22 21 19 17 15 12 0

1.0

9 12 15 21 23 26 29 33 40 55 86 148 238 406 434 317 205 130 89 62 50 41 34 30 27 24 22 20 18 16 12 0

1.5

7 8 10 14 15 16 18 20 22 25 29 34 45 101 220 339 373 320 234 131 80 53 40 34 30 27 24 21 19 17 12 2

2.0

4 6 7 9 9 10 11 12 13 15 16 18 20 25 37 72 150 252 336 312 216 109 58 42 34 30 27 24 20 18 13 8

2.5

3 4 5 6 7 7 8 8 9 10 11 12 13 16 19 25 39 75 142 262 308 229 108 58 41 34 30 27 22 19 14 11

3.0

1 2 3 4 4 5 5 6 6 7 7 8 8 10 12 14 17 22 31 76 169 288 236 122 64 43 35 30 24 20 16 11

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.1 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0

0 0 0 154 568 936 524 217 172 149 126 107 97 86 76 69 63 58 53 48 46 42 38 34 31 30 28 27 24 20 19 0

.10

0 0 0 19 109 415 762 603 346 230 176 143 119 96 84 74 68 62 57 50 47 44 40 35 32 30 29 27 24 21 19 0

.20

0 0 0 0 13 77 302 609 605 432 297 217 167 115 94 81 73 66 60 53 48 45 41 37 33 31 29 28 25 21 19 0

.30

0 0 0 0 9 54 219 479 563 476 357 263 199 129 99 85 75 68 62 54 49 45 41 37 33 31 29 28 25 21 19 0

.40

0 0 0 0 0 6 38 159 372 500 484 399 309 183 123 96 82 73 66 58 51 46 42 38 34 31 30 28 25 22 19 0

.50

0 0 0 0 0 4 27 115 287 429 465 421 346 213 138 103 86 76 68 59 52 47 43 39 34 32 30 29 25 22 19 0

.75

0 0 0 0 0 0 1 10 46 132 246 338 381 341 243 165 119 94 80 67 58 50 45 41 37 33 31 29 26 23 19 0

1.0

0 0 0 0 0 0 0 1 4 22 69 149 241 357 331 246 170 122 96 76 64 54 47 42 38 34 32 30 27 24 19 0

1.5

0 0 0 0 0 0 0 0 0 0 0 1 4 41 142 258 310 285 224 142 97 71 55 47 43 39 35 32 29 25 20 4

2.0

0 0 0 0 0 0 0 0 0 0 0 0 0 1 10 49 130 221 279 255 182 108 70 55 47 42 38 34 30 27 20 11

2.5

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 14 52 119 224 256 193 107 70 55 47 42 38 32 28 22 17

3.0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 9 52 141 240 199 117 74 56 48 43 35 30 24 18

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.1 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0

0 0 0 0 70 539 377 196 171 154 134 117 108 99 89 83 77 72 67 61 59 56 51 46 43 42 40 38 34 30 28 0

.10

0 0 0 0 47 375 376 256 199 169 146 126 114 102 92 85 79 73 68 62 59 56 52 47 43 42 40 38 34 30 28 0

.20

0 0 0 0 0 31 260 338 283 227 189 160 138 112 99 90 83 77 72 64 60 57 53 48 44 42 41 39 35 30 28 0

.30

0 0 0 0 0 0 21 180 285 284 246 208 176 131 110 97 88 82 76 68 62 59 54 50 45 43 41 39 36 31 28 0

.40

0 0 0 0 0 0 14 125 232 266 253 223 192 142 115 100 91 83 77 69 63 59 55 50 45 43 41 40 36 31 28 0

.50

0 0 0 0 0 0 9 86 183 239 248 231 205 154 122 104 93 85 79 71 64 59 55 51 46 43 41 40 36 32 28 0

.75

0 0 0 0 0 0 3 31 87 147 190 211 213 184 147 121 103 92 84 75 67 61 57 52 47 44 42 40 37 32 28 0

1.0

0 0 0 0 0 0 0 0 1 13 45 92 141 205 197 165 134 112 98 84 75 65 59 55 50 46 43 41 38 34 28 0

1.5

0 0 0 0 0 0 0 0 0 0 0 2 9 51 118 170 183 167 143 111 92 77 65 59 54 50 45 43 39 35 28 2

2.0

0 0 0 0 0 0 0 0 0 0 0 0 0 2 15 51 103 148 168 156 127 96 76 65 58 54 49 45 41 37 29 12

2.5

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 9 31 69 131 159 140 101 78 66 59 54 50 43 39 31 24

3.0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 11 46 101 151 134 99 77 65 59 54 45 41 33 26

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = II

* * * TC = 0.1 HR * * *

SHEET 1 OF 10

5-29 A-1-69

5-30 A-1-70

Exhibit 5-II, continued: Tabular hydrograph unit discharges (csm/in) for type II rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.2 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 23 31 47 209 403 739 800 481 250 166 128 102 86 70 61 54 49 44 40 35 33 30 27 24 21 20 19 18 16 13 12 0

.10 19 26 39 86 168 325 601 733 565 355 229 161 122 83 69 59 53 47 43 37 34 31 28 25 22 21 19 18 16 14 12 0

.20 17 23 32 49 74 136 262 488 652 594 435 298 207 115 81 67 58 51 46 40 35 32 29 26 23 21 20 19 16 14 12 0

.30 16 22 30 46 64 112 212 396 566 585 485 360 258 139 90 71 60 53 48 41 36 32 29 26 23 21 20 19 16 14 12 0

.40 14 19 25 37 43 57 94 173 322 485 551 507 409 227 129 87 68 58 52 44 38 33 30 27 24 21 20 19 17 14 12 0 .50 13 18 24 35 40 52 80 142 262 410 504 506 441 269 153 98 73 61 53 45 39 34 30 27 24 22 20 19 17 15 12 0 .75 10 13 17 23 26 30 34 40 55 86 150 247 349 438 360 240 151 101 75 57 47 39 33 29 26 23 21 20 18 15 12 0 1.0 9 11 14 19 21 24 26 30 35 44 62 101 167 337 413 353 245 157 104 68 53 42 35 31 28 24 22 20 18 16 12 0

1.5 6 3 10 13 14 15 17 19 21 23 26 30 37 73 166 288 356 337 264 154 91 57 42 35 30 27 24 22 19 17 13 3

2.0 4 5 7 8 9 10 10 11 12 14 15 16 18 23 31 55 114 206 291 324 239 125 63 44 35 31 28 24 20 18 14 9

2.5 3 4 5 6 6 7 7 8 9 9 10 11 12 15 18 22 32 58 111 227 298 246 122 63 43 35 31 27 22 19 15 11

3.0 1 2 3 4 4 4 5 5 6 6 7 7 8 9 11 13 16 19 27 59 138 280 248 137 70 46 36 31 25 21 16 11

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.2 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 39 180 545 697 497 276 198 158 130 110 93 81 73 67 61 56 49 46 43 39 35 32 30 29 27 24 21 19 0

.10 0 0 0 2 27 129 407 600 532 361 252 190 150 108 90 79 71 65 59 52 48 44 41 36 32 31 29 28 25 21 19 0

.20 0 0 0 2 19 92 302 501 521 415 306 228 176 119 95 82 73 67 61 53 48 45 41 37 33 31 29 28 25 21 19 0

.30 0 0 0 0 1 13 66 223 408 484 438 350 269 163 114 93 80 72 65 57 51 46 42 38 34 31 30 28 25 22 19 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

1 9 47 164 327 431 436 379 306 189 127 98 83 74 67 58 52 47 43 38 34 31 30 28 25 22 19 0 0 0 6 33 120 258 374 415 391 271 173 121 95 81 72 62 55 48 44 40 35 32 30 29 26 22 19 0 0 0 2 13 50 126 221 302 348 323 240 167 121 96 81 68 59 50 45 41 37 33 31 29 26 23 19 0 0 0 0 0 1 6 24 69 139 285 331 280 204 145 109 82 68 56 48 43 39 35 32 30 27 24 19 0

1.5 0 0 0 0 0 0 0 0 0 0 0 0 1 16 79 186 271 288 247 165 110 76 58 49 44 40 35 32 29 26 20 5

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 24 80 163 235 262 202 123 76 58 49 43 39 35 30 27 21 13

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 6 28 77 179 242 207 120 75 57 48 43 39 32 29 22 17

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 30 101 207 227 130 80 59 49 44 35 30 24 18

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.2 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 7 98 371 322 221 182 158 137 120 104 94 86 80 74 69 62 60 57 52 47 44 42 40 39 35 30 28 0

.10 0 0 0 0 4 67 270 305 249 204 174 149 130 108 97 88 82 76 71 64 60 57 53 48 44 42 41 39 35 30 28 0

.20 0 0 0 0 0 3 45 195 268 255 221 189 163 125 106 95 87 80 75 67 62 58 54 49 45 43 41 39 35 31 28 0

.30 0 0 0 0 0 2 31 140 226 245 229 203 176 134 111 98 89 82 76 68 62 59 55 50 45 43 41 39 36 31 28 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 1 21 101 184 225 228 211 188 144 117 101 91 84 78 69 63 59 55 50 45 43 41 40 36 31 28 0 0 0 1 14 72 146 199 218 213 175 137 113 99 89 82 73 66 60 56 52 47 43 42 40 36 32 28 0 0 0 0 5 28 71 121 162 188 193 161 133 112 98 88 78 70 62 57 53 48 44 42 41 37 33 28 0 0 0 0 0 0 2 13 38 77 154 186 174 147 122 105 89 78 68 60 56 51 46 43 42 38 34 28 0

1.5 0 0 0 0 0 0 0 0 0 0 0 0 2 22 71 129 163 168 150 120 98 80 67 60 55 51 46 43 40 36 28 4

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 5 25 65 112 146 157 134 103 79 67 60 55 50 46 41 38 29 14

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 8 26 60 117 148 136 101 79 66 59 54 50 43 39 31 24

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 9 40 90 142 130 99 78 66 59 54 45 41 33 26

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = II

* * * TC = 0.2 HR * * *

SHEET 2 OF 10

GaSWCC

GaSWCC

Exhibit 5-II, continued: Tabular hydrograph unit discharges (csm/in) for type II rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.3 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 20 28 41 118 235 447 676 676 459 283 196 146 114 80 66 57 51 46 42 37 33 31 28 24 22 20 19 18 16 13 12 0

.10 19 26 39 99 189 361 571 641 520 362 251 181 136 89 70 60 53 48 43 37 34 31 28 25 22 21 19 18 16 14 12 0

.20 17 23 32 53 83 154 292 478 587 542 422 308 223 127 86 68 58 52 46 40 35 32 29 26 23 21 20 19 16 14 12 0

.30 16 22 30 49 72 127 237 398 524 536 460 359 268 151 97 73 61 53 48 41 36 32 29 26 23 21 20 19 16 14 12 0

.40 14 19 25 37 45 63 105 193 330 459 510 477 398 237 139 92 70 59 52 44 38 34 30 27 24 21 20 19 17 14 12 0 .50 13 18 24 35 42 56 89 158 272 397 472 475 424 274 163 104 76 62 54 46 39 34 30 27 24 22 20 19 17 15 12 0 .75 11 14 19 26 30 34 42 59 95 160 250 339 417 398 299 196 128 89 69 54 45 37 32 29 26 23 21 20 17 15 12 0 1.0 9 11 14 19 21 24 27 30 36 46 68 109 174 328 396 346 248 163 109 70 54 43 35 31 28 24 22 20 18 16 12 0

1.5 6 8 10 13 14 15 17 19 21 23 26 31 38 77 169 282 347 330 264 158 94 58 42 35 31 27 24 22 19 17 13 3

2.0 4 5 7 8 9 10 10 11 12 14 15 16 18 23 32 57 116 205 285 317 239 128 64 44 36 31 28 25 20 18 14 9

2.5 2 4 5 6 6 7 7 8 9 9 10 11 12 15 18 23 33 60 113 223 293 245 125 65 44 35 31 27 22 19 15 11

3.0 1 2 3 4 4 4 5 5 6 6 7 7 8 9 11 13 16 20 27 61 138 275 246 139 72 46 36 31 25 21 16 11

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.3 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 11 64 251 525 574 454 303 221 173 140 104 88 77 70 64 58 51 47 44 40 36 32 31 29 28 24 21 19 0

.10 0 0 0 0 7 45 183 411 520 476 360 268 205 133 101 85 76 69 62 55 49 45 41 37 33 31 30 28 25 21 19 0

.20 0 0 0 0 5 32 132 318 452 468 396 310 240 151 109 90 78 70 64 56 50 46 42 38 33 31 30 28 25 22 19 0

.30 0 0 0 0 0 3 22 96 244 383 440 411 344 217 142 105 87 76 69 60 53 47 43 39 35 32 30 29 26 22 19 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 2 16 69 186 317 399 407 365 246 160 115 92 79 71 61 54 48 43 39 35 32 30 29 26 22 19 0 0 0 2 11 50 140 258 352 389 327 223 149 110 89 77 66 57 50 45 41 36 33 31 29 26 23 19 0 0 0 1 4 20 63 135 219 290 335 281 205 146 110 89 72 62 52 46 42 38 34 31 30 27 23 19 0 0 0 0 0 0 2 9 32 78 216 320 306 243 176 128 90 72 59 49 44 40 36 33 31 28 24 19 1

1.5 0 0 0 0 0 0 0 0 0 0 0 0 2 20 84 185 264 281 246 168 112 77 58 49 44 40 36 32 29 26 20 5

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 12 50 121 200 257 224 141 83 61 50 44 40 36 31 28 21 14

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 16 51 145 239 223 137 82 60 50 44 40 33 29 22 17

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 19 74 184 224 146 89 63 51 45 36 31 24 18

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.3 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 1 25 151 299 277 219 187 162 141 113 100 90 84 78 72 65 61 58 53 48 44 42 41 39 35 31 28 0

.10 0 0 0 0 1 17 106 235 263 234 202 175 152 120 104 93 85 79 73 66 61 58 54 49 44 42 41 39 35 31 28 0

.20 0 0 0 0 0 0 12 75 182 236 234 213 188 144 116 101 91 84 78 70 63 59 55 50 45 43 41 40 36 31 28 0

.30 0 0 0 0 0 0 8 52 138 203 224 217 197 154 123 105 94 86 79 71 64 59 55 51 46 43 42 40 36 32 28 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 5 37 105 170 206 213 203 164 131 110 97 88 81 72 65 60 56 51 46 43 42 40 36 32 28 0 0 0 0 4 26 78 140 184 203 191 155 126 107 95 86 76 69 62 57 53 48 44 42 41 37 33 28 0 0 0 0 1 10 34 73 117 153 184 173 146 122 105 94 82 73 64 58 54 49 45 43 41 37 33 28 0 0 0 0 0 0 0 4 17 42 114 168 178 159 134 114 94 82 70 61 57 52 47 44 42 39 35 28 0

1.5 0 0 0 0 0 0 0 0 0 0 0 0 1 10 44 98 144 163 157 130 105 84 69 61 56 52 47 44 40 36 29 6

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 14 44 87 127 153 141 110 83 69 61 56 51 47 42 38 30 17

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 16 42 97 138 145 107 82 68 60 55 51 43 40 32 25

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 27 71 127 139 105 81 68 60 55 46 41 33 27

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = II

* * * TC = 0.3 HR * * *

SHEET 3 OF 10

5-31 A-1-71

5-32 A-1-72

Exhibit 5-II, continued: Tabular hydrograph unit discharges (csm/in) for type II rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.4 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 18 25 36 77 141 271 468 592 574 431 298 216 163 104 77 63 55 49 44 38 34 31 28 25 22 21 20 18 16 14 12 0

.10 18 24 34 67 116 219 385 523 557 473 357 263 196 119 84 67 57 51 46 39 35 32 29 25 22 21 20 19 16 14 12 0

.20 15 20 28 44 59 97 179 316 454 523 489 401 309 178 112 81 65 56 49 42 37 33 30 26 23 21 20 19 17 14 12 0

.30 15 20 27 41 53 82 147 260 389 478 486 429 349 210 129 89 69 58 51 43 38 33 30 27 24 21 20 19 17 14 12 0

.40 13 17 23 33 38 48 71 121 214 331 429 467 442 308 189 120 85 66 56 47 41 35 31 28 24 22 20 19 17 15 12 0 .50 12 16 22 31 36 44 62 102 176 279 379 438 440 339 218 137 94 71 59 49 42 35 31 28 25 22 21 19 17 15 12 0 .75 10 13 17 24 26 30 35 45 65 106 170 251 326 393 341 245 164 112 81 59 48 39 33 30 26 23 21 20 18 15 12 0 1.0 8 10 13 17 19 21 24 27 31 37 50 75 118 251 360 376 292 205 138 83 60 45 36 32 28 25 22 21 18 16 12 1

1.5 6 7 9 12 13 14 15 17 19 21 23 26 31 56 121 224 311 333 293 192 115 66 45 36 31 28 25 22 19 17 13 4

2.0 4 5 6 8 8 9 10 10 11 12 14 15 16 20 27 43 85 159 243 306 264 154 74 47 37 32 28 25 21 18 14 9

2.5 2 3 4 5 6 6 7 7 8 9 9 10 11 13 16 20 27 46 85 184 285 262 147 74 47 37 32 28 22 19 15 11

3.0 1 2 2 3 4 4 4 5 5 6 6 7 7 8 10 12 14 17 23 47 109 227 268 160 83 50 38 32 25 21 16 11

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.4 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 4 26 113 296 480 495 413 306 234 186 127 100 84 74 67 61 54 49 45 41 37 33 31 29 28 25 21 19 0

.10 0 0 0 0 2 18 81 224 395 462 430 347 272 172 121 96 82 73 66 57 51 46 42 38 34 31 30 28 25 22 19 0

.20 0 0 0 0 2 13 59 169 320 414 424 373 305 196 134 103 85 75 67 59 52 47 43 39 34 32 30 29 25 22 19 0

.30 0 0 0 0 0 1 9 42 127 255 361 403 383 274 181 127 99 83 73 63 55 48 44 40 36 32 30 29 26 23 19 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 1 6 30 94 202 308 372 379 298 203 141 106 87 76 65 56 49 44 40 36 32 31 29 26 23 19 0 0 0 0 4 21 70 158 258 334 364 270 187 133 102 85 70 60 51 46 41 37 33 31 30 26 23 19 0 0 0 0 2 8 30 76 145 219 321 305 241 177 130 102 78 65 55 47 43 38 34 32 30 27 24 19 0 0 0 0 0 0 1 4 15 42 150 267 308 272 209 154 103 79 62 51 45 41 37 33 31 28 25 19 1

1.5 0 0 0 0 0 0 0 0 0 0 0 0 1 10 51 136 226 274 263 195 131 85 62 51 45 41 36 33 29 26 20 6

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 6 31 86 162 252 239 162 93 64 52 45 41 37 31 28 21 15

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 9 33 112 202 235 155 92 64 52 45 41 33 29 23 18

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 21 76 182 221 148 90 63 51 45 36 31 24 18

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.4 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 7 59 168 245 257 213 186 163 128 109 96 88 81 75 67 62 58 54 50 45 43 41 39 35 31 28 0

.10 0 0 0 0 0 0 5 41 125 205 240 222 198 154 123 106 94 86 79 71 64 60 56 51 46 43 42 40 36 32 28 0

.20 0 0 0 0 0 0 3 28 93 168 216 220 205 164 131 110 97 88 81 72 65 60 56 51 46 43 42 40 36 32 28 0

.30 0 0 0 0 0 0 0 2 20 69 135 189 209 192 155 126 107 95 86 77 69 62 57 53 48 44 42 41 37 33 28 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 1 14 50 106 161 193 202 163 133 112 98 89 78 70 62 58 53 48 44 42 41 37 33 28 0 0 0 0 1 9 37 83 135 174 194 171 140 117 102 91 80 71 63 58 54 49 45 43 41 37 33 28 0 0 0 0 0 0 3 15 40 76 147 177 169 146 124 107 90 79 68 60 56 51 47 43 42 38 34 28 0 0 0 0 0 0 0 1 7 21 78 141 173 167 146 125 101 86 73 63 58 53 48 45 42 39 35 28 1

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 5 26 71 121 153 159 139 113 89 72 63 57 53 48 44 40 37 29 7

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 16 45 86 138 150 125 93 74 64 58 53 48 42 39 31 20

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 17 59 112 143 121 91 73 63 57 53 45 40 32 26

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 11 40 101 138 117 90 73 63 57 48 42 34 27

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = II

* * * TC = 0.4 HR * * *

SHEET 4 OF 10

GaSWCC

GaSWCC

Exhibit 5-II, continued: Tabular hydrograph unit discharges (csm/in) for type II rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.5 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 17 23 32 57 94 170 308 467 529 507 402 297 226 140 96 74 61 53 47 41 36 32 29 26 23 21 20 19 16 14 12 0

.10 16 22 30 51 80 140 252 395 484 499 434 343 265 162 108 80 65 55 49 42 36 33 29 26 23 21 20 19 16 14 12 0

.20 14 19 25 38 47 69 116 207 332 434 477 449 378 238 149 101 77 62 53 45 39 34 30 27 24 22 20 19 17 14 12 0

.30 13 18 24 35 43 60 97 170 278 382 446 448 401 270 171 114 83 66 56 46 40 34 31 27 24 22 20 19 17 15 12 0

.40 12 15 21 29 33 40 53 83 141 233 332 408 434 361 243 157 107 79 64 51 43 36 32 28 25 22 21 20 17 15 12 0 .50 11 15 20 28 31 37 48 71 118 194 286 367 412 378 271 178 119 86 68 53 44 37 32 29 25 23 21 20 17 15 12 0 .75 9 11 14 19 21 24 27 31 37 49 74 118 182 319 374 328 244 169 117 76 56 43 35 31 28 25 22 21 18 16 12 1 1.0 7 9 12 16 17 19 21 24 27 32 40 55 83 188 309 359 322 245 172 102 68 49 38 32 29 26 23 21 19 16 12 1

1.5 5 7 8 11 12 13 14 15 17 19 21 23 27 43 89 175 269 322 309 225 140 77 49 38 32 29 25 23 20 17 13 5

2.0 3 4 6 7 8 8 9 10 10 11 12 14 15 18 23 35 65 123 202 297 280 181 88 52 39 33 29 26 21 19 14 10

2.5 2 3 4 5 5 6 6 7 7 8 9 9 10 12 15 18 24 36 66 150 244 278 171 87 52 39 33 29 23 20 15 11

3.0 1 1 2 3 3 4 4 4 5 5 6 6 7 8 9 11 13 16 20 37 86 198 263 182 96 56 40 33 26 21 16 11

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.5 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 1 9 53 157 314 433 439 379 299 237 159 118 95 81 71 65 56 50 46 42 38 34 31 30 28 25 22 19 0

.10 0 0 0 0 1 6 37 117 248 372 416 391 330 218 150 113 92 79 70 60 53 47 43 39 35 32 30 29 26 22 19 0

.20 0 0 0 0 1 4 26 87 194 313 382 388 349 244 167 122 97 82 72 62 54 48 43 39 35 32 30 29 26 22 19 0

.30 0 0 0 0 0 0 3 19 64 151 259 341 372 316 223 156 117 94 80 67 58 50 45 41 36 33 31 29 26 23 19 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 2 13 47 116 211 298 354 328 245 172 127 100 83 69 59 51 45 41 37 33 31 29 26 23 19 0 0 0 0 1 9 34 89 170 255 341 303 225 161 120 96 76 64 54 47 42 38 34 31 30 27 24 19 0 0 0 0 1 4 14 41 89 152 270 305 268 207 155 118 87 70 57 48 44 39 35 32 30 27 24 19 0 0 0 0 0 0 0 2 7 22 98 212 295 285 237 181 120 88 67 53 46 42 38 34 31 28 25 19 2

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 5 30 95 183 249 265 217 152 96 66 53 46 41 37 34 30 26 20 8

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 18 59 125 221 245 182 105 69 54 47 42 38 32 28 22 16

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 21 84 174 230 172 103 69 54 46 42 34 30 23 18

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 13 56 157 217 163 101 68 53 46 37 31 25 18

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P =0.50

* * * TC = 0.5 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 2 26 89 170 217 229 200 179 144 119 104 93 85 78 70 64 59 55 51 46 43 41 40 36 32 28 0

.10 0 0 0 0 0 0 1 18 65 135 190 216 205 170 137 115 101 91 83 74 67 61 56 52 47 44 42 40 36 32 28 0

.20 0 0 0 0 0 0 1 12 47 106 162 198 203 178 145 121 105 94 85 76 68 61 57 52 48 44 42 40 37 32 28 0

.30 0 0 0 0 0 0 0 1 8 34 82 135 177 194 168 139 117 102 92 80 71 63 58 54 49 45 43 41 37 33 28 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 6 25 63 111 155 189 174 146 122 106 94 82 73 64 58 54 50 45 43 41 37 33 28 0 0 0 0 0 4 18 48 90 133 184 177 152 128 110 97 84 74 65 59 55 50 45 43 41 38 33 28 0 0 0 0 0 1 7 22 47 80 142 169 164 144 124 108 91 79 68 61 56 51 47 44 42 38 34 28 0 0 0 0 0 0 0 1 3 11 51 112 155 166 154 134 109 91 76 65 59 54 49 45 43 39 35 28 2

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 2 16 50 97 136 154 145 121 95 75 64 58 54 49 45 41 37 29 10

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 18 47 86 134 146 125 94 75 64 58 53 49 42 39 31 21

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 11 44 95 140 127 97 77 65 58 54 45 41 33 26

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 7 29 86 135 122 95 76 65 58 49 43 35 27

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = II

* * * TC = 0.5 HR * * *

SHEET 5 OF 10

5-33 A-1-73

5-34 A-1-74

Exhibit 5-II, continued: Tabular hydrograph unit discharges (csm/in) for type II rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.75 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 13 18 24 36 46 68 115 194 294 380 424 410 369 252 172 123 93 74 61 49 41 35 31 27 24 22 20 19 17 15 12 0

.10 13 17 23 34 42 59 97 162 250 337 395 405 381 279 191 135 100 79 65 51 42 36 31 28 25 22 21 19 17 15 12 0

.20 11 15 20 28 32 39 52 82 135 211 295 362 391 351 255 178 127 95 75 57 46 38 32 29 26 23 21 20 17 15 12 0

.30 11 14 19 26 30 36 47 70 113 179 256 326 379 360 277 196 140 103 80 60 48 38 33 29 26 23 21 20 18 15 12 0

.40 10 12 16 22 25 28 33 42 61 96 151 221 291 367 336 255 182 131 98 69 54 42 34 30 27 24 22 20 18 16 12 0 .50 9 12 16 21 24 27 31 39 53 82 128 190 258 358 343 274 200 144 106 74 56 43 35 30 27 24 22 20 18 16 12 0 .75 8 10 13 17 18 21 23 26 31 39 55 82 122 230 314 329 281 217 161 104 72 51 38 33 29 26 23 21 19 16 12 1 1.0 6 8 10 13 14 15 17 19 21 23 27 32 42 89 177 272 319 303 249 163 105 66 45 36 31 27 24 22 19 17 13 3

1.5 4 6 7 9 10 10 11 12 14 15 16 18 20 27 46 90 163 241 295 275 204 119 66 45 35 31 27 24 20 18 13 7

2.0 3 4 5 6 7 7 8 9 9 10 11 12 13 16 20 28 48 89 151 245 274 213 115 65 44 35 30 27 22 19 14 10

2.5 1 2 3 4 4 5 5 6 6 7 7 8 8 10 12 14 17 24 37 86 170 260 219 127 71 47 36 31 24 20 16 11

3.0 1 1 2 3 3 3 4 4 4 5 5 5 6 7 8 10 11 14 17 30 64 157 247 205 122 70 46 36 27 22 17 12

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC =0.75 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 1 6 30 86 174 266 326 348 328 246 181 138 110 92 79 66 57 49 44 40 36 32 31 29 26 23 19 0

.10 0 0 0 0 0 1 4 22 65 137 223 292 329 303 228 170 131 106 89 73 61 52 46 41 37 33 31 29 26 23 19 0

.20 0 0 0 0 0 0 3 15 48 108 185 256 305 321 245 184 141 112 93 75 63 53 46 42 37 34 31 30 27 23 19 0

.30 0 0 0 0 0 0 2 11 36 84 151 221 277 308 260 199 152 120 98 78 65 54 47 42 38 34 31 30 27 23 19 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 1 8 27 65 122 188 286 301 243 187 144 114 87 71 57 48 43 39 35 32 30 27 24 19 1 0 0 0 1 6 20 50 98 158 263 292 254 200 155 122 91 74 59 49 44 40 35 32 30 27 24 19 1 0 0 0 0 0 2 8 23 51 140 231 269 253 211 167 119 90 68 53 46 42 37 34 31 28 25 19 2 0 0 0 0 0 0 0 1 4 29 96 186 249 261 231 169 120 84 61 50 44 40 36 33 29 26 20 5

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 1 8 34 91 163 220 241 197 131 83 61 50 44 40 35 31 27 21 12

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 11 36 85 174 226 200 127 82 60 49 44 39 32 29 22 17

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 6 37 105 196 214 135 87 62 51 44 36 31 24 18

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 24 96 205 189 130 85 62 50 39 32 26 18

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.75 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 2 16 45 92 137 166 185 170 146 125 110 98 89 79 70 63 58 53 48 44 42 41 37 33 28 0

.10 0 0 0 0 0 0 0 1 11 34 73 115 149 180 163 141 122 107 96 84 74 65 59 54 50 45 43 41 38 33 28 0

.20 0 0 0 0 0 0 0 1 8 25 57 96 131 173 166 146 126 111 99 86 76 66 59 55 50 46 43 41 38 34 28 0

.30 0 0 0 0 0 0 0 0 1 5 18 44 79 143 170 160 141 122 108 92 81 69 61 56 52 47 44 42 38 34 28 1

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 4 14 34 64 127 166 162 145 127 111 95 82 70 62 57 52 47 44 42 38 34 28 1 0 0 0 0 0 0 2 10 26 82 138 162 157 140 123 103 88 75 64 58 53 49 45 43 39 35 28 2 0 0 0 0 0 0 1 4 12 47 98 139 154 148 135 113 96 80 67 60 55 50 46 43 39 36 29 3 0 0 0 0 0 0 0 0 0 6 30 73 119 146 151 134 113 91 74 63 58 53 48 45 41 37 29 7

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 9 30 66 105 143 143 117 90 73 63 57 52 48 42 39 30 18

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 11 30 77 121 137 114 88 72 63 57 52 44 40 32 25

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 19 55 111 132 111 87 71 62 56 47 42 34 27

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 12 51 112 128 108 86 71 62 51 44 36 27

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = II

* * * TC = 0.75 HR * * *

SHEET 6 OF 10

GaSWCC

GaSWCC

Exhibit 5-II, continued: Tabular hydrograph unit discharges (csm/in) for type II rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 1.0 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 11 15 20 29 35 47 72 112 168 231 289 329 357 313 239 175 133 103 83 63 50 40 33 29 26 23 21 20 17 15 12 0

.10 10 13 17 24 27 33 42 62 95 144 202 260 306 340 293 222 165 126 98 72 56 43 35 30 27 24 22 20 18 15 12 0

.20 10 13 17 23 26 30 38 54 82 123 176 232 281 332 303 238 179 136 105 76 59 45 35 30 27 24 22 20 18 16 12 1

.30 9 12 16 22 24 28 35 48 70 105 152 205 256 323 310 254 193 146 113 81 61 46 36 31 27 24 22 20 18 16 12 1

.40 8 11 14 19 21 23 27 32 42 61 91 132 181 276 318 294 237 181 138 95 70 51 39 32 28 25 23 21 18 16 12 1 .50 8 10 13 18 20 22 25 30 38 53 78 114 159 253 311 300 251 195 149 102 74 53 40 33 29 25 23 21 18 16 12 1 .75 7 8 11 14 16 17 19 21 25 30 38 53 76 146 228 284 293 256 208 143 99 66 46 36 31 27 24 22 19 17 13 2 1.0 5 7 8 11 12 13 14 16 17 19 22 25 31 57 111 188 256 286 272 208 144 90 56 41 33 29 26 23 20 17 13 4

1.5 4 5 6 8 8 9 10 11 12 13 14 15 17 22 33 59 107 171 231 268 235 157 88 56 41 33 29 25 21 18 14 8

2.0 2 3 4 5 5 6 6 7 7 8 9 9 10 12 15 19 27 44 78 157 231 252 167 96 59 42 34 29 23 20 15 11

2.5 1 2 2 3 4 4 4 5 5 6 6 7 7 8 10 12 15 19 27 58 120 214 241 159 94 59 42 34 26 21 16 11

3.0 0 1 1 2 2 3 3 3 4 4 4 5 5 6 7 8 10 12 14 22 44 113 214 231 152 91 58 42 29 23 17 12

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC =1.0 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 1 4 16 42 83 137 195 243 271 292 227 178 143 117 98 79 66 55 47 42 38 34 31 30 27 23 19 0

.10 0 0 0 0 0 0 3 12 32 66 113 168 218 279 260 213 169 136 113 88 72 59 49 43 39 35 32 30 27 24 19 1

.20 0 0 0 0 0 0 2 9 24 52 93 143 193 271 271 225 180 145 119 92 75 60 50 44 39 35 32 30 27 24 19 1

.30 0 0 0 0 0 0 1 6 18 41 75 120 169 246 264 234 191 153 125 96 78 62 51 44 40 36 33 31 27 24 19 1

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 1 4 14 32 61 100 190 251 259 222 181 146 109 86 67 53 46 41 37 33 31 28 25 19 2 0 0 0 1 3 10 24 49 83 168 237 254 230 191 155 115 90 69 54 47 42 37 34 31 28 25 19 2 0 0 0 0 0 1 4 12 25 76 150 213 239 228 198 149 112 82 61 50 44 39 35 32 29 26 20 4 0 0 0 0 0 0 0 1 2 15 51 113 182 226 234 197 150 104 72 56 47 42 38 34 30 27 20 7

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 18 51 104 162 220 210 158 102 71 56 47 42 37 31 28 22 13

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 20 49 121 187 209 152 100 70 55 47 41 34 29 23 17

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 7 32 87 171 199 146 98 69 54 46 37 31 24 18

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 13 62 158 192 151 103 73 56 41 34 26 18

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 1.0 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 1 7 21 42 71 101 126 160 154 138 123 110 100 87 77 67 60 55 50 46 43 41 38 34 28 1

.10 0 0 0 0 0 0 0 1 5 15 33 58 87 134 156 149 134 120 108 93 82 71 62 57 52 47 44 42 38 34 28 1

.20 0 0 0 0 0 0 0 1 4 12 26 48 74 123 153 153 137 123 111 95 84 72 63 57 52 47 44 42 38 34 28 1

.30 0 0 0 0 0 0 0 0 3 9 20 38 62 111 143 150 140 127 114 98 86 73 63 58 53 48 45 42 39 35 28 1

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 2 6 16 31 75 120 145 148 137 123 106 91 77 66 59 54 49 45 43 39 35 29 2 0 0 0 0 0 1 5 12 25 64 109 139 146 139 127 108 94 79 67 60 55 50 46 43 39 36 29 3 0 0 0 0 0 0 2 5 12 39 78 115 136 140 134 117 101 84 70 62 56 51 47 44 40 36 29 4 0 0 0 0 0 0 0 0 1 7 26 59 96 125 139 133 117 97 78 66 59 54 49 46 41 37 29 8

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 9 26 54 86 123 133 119 95 77 66 59 54 49 43 39 31 17

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 10 25 64 104 129 116 93 76 65 58 53 45 41 33 24

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 10 34 84 125 117 96 78 66 59 49 43 35 27

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 6 32 89 122 114 94 77 66 53 45 37 27

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = II

* * * TC = 1.0 HR * * *

SHEET 7 OF 10

5-35 A-1-75

5-36 A-1-76

Exhibit 5-II, continued: Tabular hydrograph unit discharges (csm/in) for type II rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 1.25 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 10 13 18 25 29 38 54 81 118 163 213 256 284 311 266 212 163 129 104 78 61 47 37 31 27 24 22 20 18 16 12 1

.10 10 13 17 23 27 34 47 69 102 143 189 234 267 297 274 226 175 138 111 82 64 48 38 31 27 24 22 20 18 16 12 1

.20 9 11 15 20 22 26 31 42 60 88 124 168 212 280 292 261 212 166 131 95 72 53 40 33 28 25 23 21 18 16 12 1

.30 8 11 14 19 21 24 29 38 53 76 108 148 190 263 288 268 224 177 140 101 76 55 41 34 29 25 23 21 18 16 12 2

.40 8 10 13 18 20 23 27 34 46 66 94 130 170 245 282 273 235 188 149 107 80 58 42 34 29 26 23 21 19 16 12 2 .50 7 9 12 16 17 19 22 25 31 41 58 82 114 190 256 279 262 222 178 127 93 65 46 36 31 27 24 22 19 17 13 2 .75 6 8 10 14 15 17 19 21 25 31 41 56 78 139 207 254 265 245 208 152 110 75 51 39 32 28 25 22 19 17 13 3 1.0 5 6 8 10 11 13 14 15 17 19 22 26 33 60 109 173 230 261 255 208 153 100 64 46 36 30 26 24 20 18 13 5

1.5 3 4 5 7 7 8 9 9 10 11 12 13 15 19 27 45 79 130 186 247 239 180 108 68 48 37 31 27 22 19 14 10

2.0 2 3 4 5 6 6 7 7 8 8 9 10 11 13 16 22 35 59 98 171 236 236 156 95 62 44 35 30 23 20 15 11

2.5 1 2 2 3 4 4 4 5 5 5 6 6 7 8 10 12 14 19 28 58 114 197 226 163 102 65 46 36 26 21 16 11

3.0 0 1 1 2 2 2 2 3 3 3 4 4 4 5 6 7 9 10 13 19 35 88 184 218 169 109 70 49 31 24 18 12

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 1.25 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 2 9 25 50 86 130 174 208 253 235 201 164 136 115 92 76 61 51 44 39 35 32 30 27 24 19 1

.10 0 0 0 0 0 0 1 6 19 40 71 110 153 217 247 227 191 157 131 103 84 66 53 46 41 36 33 31 28 24 19 2

.20 0 0 0 0 0 0 1 4 14 31 58 93 133 202 239 231 199 165 138 108 87 68 55 47 41 37 33 31 28 25 19 2

.30 0 0 0 0 0 0 0 1 3 10 24 46 77 152 210 236 222 190 158 122 97 74 58 49 43 38 34 32 28 25 20 3

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 2 8 19 37 64 134 196 232 225 198 166 127 101 77 59 50 43 38 35 32 28 25 20 3 0 0 0 0 0 2 6 14 30 82 151 206 228 217 189 146 113 85 64 52 45 40 36 33 29 26 20 5 0 0 0 0 0 1 2 7 15 49 105 164 205 218 205 166 129 95 69 55 47 41 37 33 29 26 20 6 0 0 0 0 0 0 0 0 1 9 32 77 134 185 214 203 166 120 83 63 52 45 39 35 30 27 21 10

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 11 33 72 121 184 203 171 117 82 62 51 44 39 32 29 22 15

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 7 21 67 132 194 174 123 86 64 52 45 35 31 24 18

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 13 46 121 187 166 119 84 63 52 39 32 25 18

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 8 44 129 180 160 116 83 63 44 35 27 18

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 1.25 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 1 5 13 26 44 68 91 125 142 142 128 117 107 94 83 72 63 57 52 47 44 42 38 34 28 2

.10 0 0 0 0 0 0 0 0 3 10 20 36 57 100 129 140 136 125 114 100 88 76 65 59 54 49 45 43 39 35 29 3

.20 0 0 0 0 0 0 0 0 2 7 16 30 48 90 122 139 139 127 117 102 90 77 66 60 54 49 45 43 39 35 29 3

.30 0 0 0 0 0 0 0 0 0 2 5 12 24 59 98 126 137 134 125 109 96 82 69 61 56 51 46 44 40 36 29 4

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 1 4 10 19 51 89 119 134 136 127 112 98 83 70 62 56 51 47 44 40 36 29 5 0 0 0 0 0 1 3 7 15 43 79 112 131 135 129 114 100 85 71 63 57 52 47 44 40 36 29 6 0 0 0 0 0 0 0 1 3 15 39 71 102 123 130 125 112 94 78 67 60 54 49 46 41 37 29 9 0 0 0 0 0 0 0 0 1 4 17 40 71 101 121 129 121 103 84 71 62 56 51 47 42 38 30 13

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 10 26 51 92 119 125 105 86 72 63 57 52 44 40 32 23

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 11 35 72 112 122 103 85 71 63 56 47 42 34 26

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 7 24 66 111 119 101 83 71 62 51 44 36 27

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 23 71 110 116 99 82 70 55 46 37 27

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = II

* * * TC = 1.25 HR * * *

SHEET 8 OF 10

GaSWCC

GaSWCC

Exhibit 5-II, continued: Tabular hydrograph unit discharges (csm/in) for type II rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 1.5 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 9 11 15 21 25 31 41 58 82 112 147 184 216 255 275 236 198 159 129 98 76 57 43 35 30 25 23 21 18 16 12 1

.10 8 10 13 18 20 23 28 37 51 72 98 131 166 226 265 254 226 187 151 113 86 63 46 37 31 26 23 21 19 16 13 2

.20 8 10 13 17 19 22 26 33 45 63 87 116 149 212 259 259 233 197 160 119 90 66 48 38 32 27 24 22 19 16 13 2

.30 7 9 12 16 18 21 24 30 40 55 76 103 134 197 244 255 238 206 169 125 95 68 49 38 32 27 24 22 19 17 13 2

.40 7 8 11 14 15 17 19 23 28 36 49 67 91 151 208 247 252 230 196 146 109 77 54 41 34 29 25 22 19 17 13 3 .50 6 8 10 13 15 16 18 21 26 33 43 59 80 136 194 238 249 235 204 154 115 81 56 42 34 29 25 23 20 17 13 3 .75 5 7 8 11 12 13 14 16 18 21 25 32 42 76 125 179 222 240 233 193 148 102 67 48 38 32 27 24 20 18 13 5 1.0 4 5 7 8 9 10 11 12 13 14 16 18 22 34 59 101 152 201 236 230 193 135 86 59 44 35 30 26 21 18 14 7

1.5 3 4 5 6 6 7 8 8 9 10 11 12 13 16 22 34 58 95 141 203 226 197 131 84 58 43 35 29 23 20 15 10

2.0 1 2 3 4 4 5 5 6 6 7 7 8 9 10 12 16 22 34 56 110 172 218 187 126 82 57 43 34 25 21 16 11

2.5 1 1 2 2 3 3 3 4 4 4 5 5 6 7 8 9 11 14 18 34 69 141 210 190 133 87 60 44 30 23 17 12

3.0 0 0 1 1 2 2 2 2 3 3 3 3 4 5 5 6 8 9 11 16 27 66 149 204 181 128 85 58 35 25 18 12

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 1.5 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 1 6 15 31 53 80 112 144 193 225 208 186 157 134 108 89 70 56 48 42 37 34 31 28 25 20 2

.10 0 0 0 0 0 0 1 4 12 25 43 68 97 157 198 219 203 178 151 120 98 77 60 50 44 38 35 32 28 25 20 3

.20 0 0 0 0 0 0 0 1 3 9 19 35 57 114 168 201 213 196 171 135 108 84 64 53 46 40 36 33 29 26 20 4

.30 0 0 0 0 0 0 0 1 2 7 15 29 48 100 155 193 210 200 177 140 113 87 66 54 46 41 36 33 29 26 20 5

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 2 5 12 23 39 87 141 184 207 202 182 146 117 89 68 55 47 41 36 33 29 26 20 5 0 0 0 0 0 1 4 9 18 51 101 153 190 205 197 164 131 99 73 58 49 43 38 34 30 26 20 7 0 0 0 0 0 0 2 4 9 30 68 116 160 189 197 179 147 110 80 62 52 45 39 35 30 27 21 8 0 0 0 0 0 0 0 0 1 5 20 49 92 138 175 195 178 137 97 72 57 48 42 37 31 28 21 12

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 7 21 47 85 145 187 178 133 95 71 57 48 42 24 29 23 16

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 13 45 97 162 180 138 99 74 58 49 38 32 25 18

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 8 31 89 161 174 133 97 72 58 42 34 26 18

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 29 98 160 169 129 95 71 48 37 28 19

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 1.5 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 3 8 16 27 42 59 92 116 128 130 121 112 100 90 78 67 60 55 50 46 43 39 35 29 4

.10 0 0 0 0 0 0 0 2 6 12 22 35 51 84 110 125 128 123 114 102 91 79 68 61 55 50 46 43 39 35 29 4

.20 0 0 0 0 0 0 0 0 1 4 10 18 29 60 91 114 126 128 120 108 97 83 71 63 57 52 47 44 40 36 29 5

.30 0 0 0 0 0 0 0 0 1 3 8 14 24 52 83 108 123 126 122 110 98 85 72 63 57 52 48 44 40 36 29 6

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 1 2 6 12 31 60 90 112 124 126 116 104 90 75 66 59 54 49 45 41 37 29 8 0 0 0 0 0 0 2 4 9 26 53 83 106 121 125 118 106 91 77 67 60 54 49 46 41 37 29 8 0 0 0 0 0 0 1 2 5 16 36 62 88 108 119 122 112 97 81 69 62 56 51 47 42 38 30 11 0 0 0 0 0 0 0 0 0 3 10 26 49 75 98 118 121 108 90 76 66 59 54 49 43 39 31 16

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 11 25 45 80 107 118 106 89 75 65 59 53 45 41 32 23

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 11 32 63 100 115 104 87 74 65 58 48 42 34 26

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 16 48 94 113 105 89 76 66 53 45 36 27

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 15 54 96 111 103 88 75 58 48 38 28

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = II

* * * TC = 1.5 HR * * *

SHEET 9 OF 10

5-37 A-1-77

5-38 A-1-78

Exhibit 5-II, continued: Tabular hydrograph unit discharges (csm/in) for type II rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

711.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 2.0 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 7 9 12 16 18 21 27 36 49 64 82 104 127 171 201 226 208 193 171 132 105 79 58 45 36 30 26 23 20 17 13 3

.10 6 8 10 14 15 17 20 25 33 43 57 74 94 139 179 204 218 205 188 150 118 88 63 48 38 32 27 24 20 17 13 4

.20 6 8 10 13 14 16 19 23 29 39 51 66 84 128 169 198 213 207 192 157 123 91 65 49 39 33 28 24 20 17 13 4

.30 6 7 9 12 14 15 18 21 27 35 45 59 76 117 159 191 211 208 196 163 128 95 68 51 40 33 28 25 20 18 13 4

.40 5 6 8 11 12 13 15 17 20 24 31 41 53 87 128 167 197 209 205 180 145 106 75 55 43 35 30 26 21 18 14 5 .50 5 6 8 10 11 13 14 16 18 22 28 37 48 78 118 158 190 208 208 185 151 111 77 57 44 36 30 26 21 18 14 5 .75 4 6 7 9 10 11 12 13 15 18 22 27 35 58 91 129 164 191 202 194 167 125 87 63 48 38 32 27 22 18 14 6 1.0 3 4 6 7 8 8 9 10 11 12 14 16 18 28 46 74 110 147 178 201 193 156 108 76 56 43 35 30 23 19 14 8

1.5 2 3 3 5 5 5 6 6 7 8 8 9 10 12 16 23 36 57 86 137 178 195 160 113 79 58 45 36 26 21 16 11

2.0 1 2 2 3 3 4 4 4 5 5 6 6 7 8 10 12 16 23 35 67 112 169 190 154 110 78 57 44 30 23 17 11

2.5 0 1 1 2 2 2 3 3 3 4 4 4 5 6 7 8 9 12 16 28 52 105 170 185 149 107 76 56 35 26 18 12

3.0 0 0 1 1 1 1 1 2 2 2 2 3 3 3 4 5 6 7 8 12 18 41 99 161 180 152 112 80 45 30 19 12

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 2.0 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 1 3 8 15 25 38 54 74 115 148 168 185 170 159 131 110 89 70 57 49 42 38 34 29 26 20 5

.10 0 0 0 0 0 0 0 2 6 12 21 32 47 85 124 153 169 180 168 145 120 96 75 60 51 44 39 35 30 26 20 6

.20 0 0 0 0 0 0 0 2 4 10 17 27 41 75 114 146 165 175 170 149 124 99 76 62 52 45 39 35 30 27 21 6

.30 0 0 0 0 0 0 0 0 1 3 7 14 23 49 86 122 151 170 174 160 136 107 82 66 54 47 41 37 31 27 21 8

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 1 2 6 11 19 43 77 113 144 165 173 163 140 111 85 67 55 47 41 37 31 27 21 8 0 0 0 0 0 2 4 9 16 37 68 104 136 160 171 165 144 114 87 69 56 48 42 37 31 27 21 9 0 0 0 0 0 0 1 2 5 15 34 62 96 127 152 167 160 132 100 77 62 52 45 40 32 28 22 11 0 0 0 0 0 0 0 0 0 3 10 24 48 79 111 150 166 153 118 90 71 58 49 43 34 29 23 14

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 10 24 45 88 130 161 148 115 88 70 57 48 37 31 24 17

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 10 32 68 122 157 143 113 87 68 56 42 34 26 18

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 16 51 114 153 144 116 89 70 49 38 27 19

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 15 59 118 150 140 113 88 57 42 29 19

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 2.0 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 1 4 8 13 20 28 51 73 92 104 111 112 106 97 86 75 66 60 54 49 46 41 37 30 7

.10 0 0 0 0 0 0 0 1 3 6 11 17 24 45 68 87 101 109 112 107 98 88 76 67 60 55 50 46 41 37 30 8

.20 0 0 0 0 0 0 0 1 2 5 9 14 21 40 62 82 98 107 111 108 100 89 77 68 61 55 50 47 41 37 30 8

.30 0 0 0 0 0 0 0 0 0 2 4 7 12 26 46 67 86 100 108 111 104 93 80 70 63 57 52 48 42 38 30 10

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 1 3 6 10 22 41 62 81 96 106 110 105 94 81 71 63 57 52 48 42 38 30 11 0 0 0 0 0 0 1 2 4 13 27 46 67 85 99 110 108 98 85 74 66 59 54 49 43 39 31 13 0 0 0 0 0 0 0 1 2 7 18 33 52 71 88 104 108 102 89 77 68 61 55 50 44 39 31 15 0 0 0 0 0 0 0 0 0 1 5 13 25 43 62 87 103 108 97 84 73 65 59 53 45 41 32 20

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 12 24 48 74 99 106 95 83 72 64 58 48 43 34 25

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 17 37 69 99 104 94 82 72 64 52 45 36 27

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 8 27 65 95 102 95 83 73 58 49 38 28

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 8 32 68 95 101 93 82 64 52 40 28

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = II

* * * TC = 2.0 HR * * *

SHEET 10 OF 10

GaSWCC

GaSWCC

Exhibit 5-III: Tabular hydrograph unit discharges (csm/in) for type III rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.1 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 29 38 57 172 241 425 662 531 345 265 191 130 101 83 68 62 58 54 50 44 41 37 32 27 23 21 19 16 14 13 11 0

.10 26 32 47 98 147 210 353 559 540 410 313 231 164 101 80 67 61 57 53 47 43 39 34 28 24 22 19 17 14 13 11 0

.20 25 31 44 86 127 182 296 471 517 446 357 273 200 117 86 70 63 58 54 48 44 39 34 29 24 22 20 17 14 13 11 0

.30 22 28 37 57 76 110 158 250 398 477 457 390 312 178 111 83 69 62 57 51 45 41 36 31 25 23 20 18 15 13 11 0

.40 21 27 35 53 68 96 137 213 336 430 448 410 345 210 128 90 72 64 58 52 46 41 36 31 26 23 20 18 15 13 11 0 .50 19 24 30 43 49 62 85 120 182 284 382 426 415 305 188 120 86 71 63 55 49 43 38 33 27 24 21 19 15 14 11 0 .75 17 22 27 37 41 49 62 84 120 181 258 327 375 353 264 177 120 88 72 59 52 45 39 34 29 25 22 20 15 14 11 0 1.0 13 17 22 27 30 33 37 43 52 66 91 131 190 315 358 307 220 149 104 72 60 50 43 37 32 27 23 21 16 14 12 0

1.5 9 11 14 18 19 21 23 25 27 29 33 37 44 70 134 229 304 318 269 172 106 68 52 44 38 33 28 24 19 15 12 2

2.0 6 8 10 13 14 15 16 17 19 20 22 24 26 32 45 73 130 207 271 292 216 121 68 51 43 37 32 27 21 16 13 6

2.5 3 4 6 8 9 10 10 11 12 13 14 16 17 20 23 29 38 57 97 189 271 244 136 75 53 44 38 33 24 19 14 9

3.0 1 2 4 5 6 6 7 8 8 9 10 11 12 14 16 19 23 28 38 74 146 256 226 131 74 53 44 37 27 21 14 10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.1 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 48 106 296 597 496 368 300 221 155 125 106 89 83 79 74 69 62 59 54 47 40 35 32 28 25 22 20 17 0

.10 0 0 0 35 82 225 473 488 408 336 260 190 147 113 94 85 80 75 70 63 59 54 48 40 35 32 29 25 22 20 17 0

.20 0 0 0 7 26 64 171 372 449 422 365 295 225 142 109 92 84 79 74 66 61 56 50 43 36 33 30 26 22 20 17 0

.30 0 0 0 5 19 49 130 291 397 414 381 323 258 161 118 96 86 80 75 68 62 57 50 43 37 33 30 27 22 20 17 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

3 14 37 99 227 340 389 384 343 229 152 113 94 85 79 71 65 59 52 46 38 34 31 28 23 21 17 0 2 10 28 75 177 286 355 374 354 256 170 123 99 87 80 73 66 60 53 46 39 35 31 28 23 21 18 0 0 1 4 13 35 86 161 238 296 325 266 194 141 110 93 80 71 63 56 50 43 37 33 30 24 21 18 0 0 0 0 2 6 19 48 99 165 282 311 264 197 144 112 88 77 67 59 52 45 39 34 31 24 22 18 0

1.5 0 0 0 0 0 0 0 0 0 0 0 1 4 29 99 197 265 277 236 162 113 84 69 60 53 46 39 35 28 23 19 2

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 8 35 94 172 233 253 196 124 83 68 59 52 45 39 31 25 20 8

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 11 37 88 184 235 201 122 83 67 59 52 45 34 27 21 13

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 7 38 110 222 202 131 88 69 60 52 39 31 22 15

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.1 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 107 226 282 258 209 155 130 123 107 97 95 91 87 82 78 74 69 61 52 47 43 39 35 32 29 25 0

.10 0 0 0 0 0 71 174 246 254 224 178 146 130 112 100 96 92 88 83 78 75 70 62 53 48 44 40 35 32 29 25 0

.20 0 0 0 0 0 0 48 132 208 239 229 195 162 127 109 99 95 91 87 80 77 72 65 56 49 45 41 36 32 30 25 0

.30 0 0 0 0 0 0 32 99 172 216 225 205 176 136 113 101 96 92 88 81 77 72 65 57 50 45 41 37 32 30 26 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 21 73 139 191 213 208 164 131 111 100 95 91 85 79 74 68 60 51 47 43 38 33 30 26 0 0 0 0 14 53 110 164 197 204 174 139 116 103 97 92 86 80 75 68 60 52 47 43 39 33 30 26 0 0 0 0 5 22 54 96 137 166 180 159 134 115 103 96 89 83 77 70 63 54 48 44 40 33 31 26 0 0 0 0 0 0 2 10 29 60 132 175 169 146 124 109 97 89 81 74 67 59 52 47 43 34 31 27 0

1.5 0 0 0 0 0 0 0 0 0 0 0 0 2 17 58 112 150 159 148 122 104 91 81 74 67 59 51 46 38 32 28 1

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 20 54 98 133 149 133 108 90 80 73 66 58 51 42 34 29 7

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 12 35 87 131 141 111 92 81 74 66 59 46 38 30 18

3.0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 22 63 120 136 110 91 81 73 66 51 42 31 22

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = III

* * * TC = 0.1 HR * * *

SHEET 1 OF 10

5-39 A-1-79

5-40 A-1-80

Exhibit 5-III, continued: Tabular hydrograph unit discharges (csm/in) for type III rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.2 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 27 34 50 119 176 258 448 565 483 358 270 194 137 93 75 65 60 56 52 46 42 38 33 28 24 21 19 17 14 13 11 0

.10 24 30 42 70 103 151 222 372 501 489 402 314 234 128 91 73 64 59 55 49 44 40 35 30 25 22 20 17 15 13 11 0

.20 23 29 39 64 90 131 192 312 438 472 425 351 273 153 101 78 66 61 56 50 45 40 35 30 25 22 20 18 15 13 11 0

.30 21 26 33 48 59 79 114 166 263 380 441 431 378 238 141 96 75 65 60 53 47 42 37 32 26 23 21 18 15 13 11 0

.40 20 25 32 45 54 71 99 144 224 328 404 422 392 271 165 108 81 68 61 54 48 43 37 32 27 23 21 19 15 14 11 0 .50 18 22 28 38 43 51 64 88 125 191 282 363 402 356 241 151 102 78 66 57 51 44 39 34 28 24 22 19 15 14 11 0 .75 15 18 23 30 33 37 42 50 64 87 125 184 253 359 341 260 177 121 89 67 57 48 42 36 31 26 23 21 16 14 12 0 1.0 12 16 20 25 28 30 33 37 43 53 68 94 135 251 345 330 260 181 125 81 63 52 44 38 33 28 24 21 17 14 12 0

1.5 8 10 13 17 18 19 21 23 25 27 30 33 38 55 99 179 266 308 289 201 124 74 54 45 39 34 29 24 19 15 12 2

2.0 5 7 9 12 13 14 15 16 17 19 20 22 24 29 38 57 99 166 238 284 239 141 75 54 44 38 33 28 21 17 13 6

2.5 2 4 5 7 8 9 10 10 11 12 13 14 16 18 22 26 33 46 75 155 240 264 154 83 56 46 39 34 25 19 14 9

3.0 1 2 3 5 5 6 6 7 8 8 9 10 11 13 15 18 21 25 33 59 118 220 250 147 82 56 45 39 28 22 14 10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.2 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 17 49 115 297 489 462 379 307 230 167 119 98 86 81 76 72 64 60 55 48 41 36 32 29 26 22 20 17 0

.10 0 0 0 12 37 89 228 402 442 400 338 266 200 131 104 89 82 78 73 65 61 56 49 42 36 33 29 26 22 20 17 0

.20 0 0 0 1 8 27 69 175 326 403 401 359 297 182 126 100 88 81 76 69 63 58 51 44 37 34 30 27 23 21 17 0

.30 0 0 0 1 6 20 52 134 262 356 386 368 321 208 140 107 91 83 78 70 64 58 52 45 38 34 31 27 23 21 17 0

.40 0 0 0 1 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

4 15 40 103 209 307 360 365 336 234 157 116 95 85 79 72 65 59 53 46 39 34 31 28 23 21 17 0 0 3 11 30 78 165 260 327 352 305 213 147 111 93 84 75 68 61 55 48 41 35 32 29 23 21 18 0 0 1 5 14 37 83 150 220 276 311 264 196 144 112 94 80 72 64 56 50 43 37 33 30 24 21 18 0 0 0 0 0 2 7 20 48 94 215 299 286 230 171 128 95 81 69 61 54 47 40 35 32 25 22 18 0

1.5 0 0 0 0 0 0 0 0 0 0 0 0 2 13 56 139 224 266 253 186 128 89 71 61 54 48 41 36 29 23 19 3

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 17 58 126 196 245 214 140 89 71 61 54 47 40 32 25 20 9

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 21 57 145 228 213 136 89 70 60 53 46 35 28 21 13

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 23 78 180 215 145 94 72 61 54 41 32 22 15

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.2 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 10 110 206 245 245 208 162 137 117 102 96 93 90 85 79 76 71 63 54 48 44 40 36 32 29 25 0

.10 0 0 0 0 0 7 76 163 217 235 217 181 152 122 106 98 94 90 86 80 76 71 64 55 49 45 41 36 32 29 25 0

.20 0 0 0 0 0 0 5 52 126 187 219 218 193 145 119 104 97 93 89 83 78 73 66 58 50 46 42 37 32 30 26 0

.30 0 0 0 0 0 0 3 36 96 156 198 211 199 155 125 108 99 94 90 84 79 74 67 59 51 46 42 38 32 30 26 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 2 24 72 128 175 199 184 147 121 106 98 93 87 81 76 69 61 53 48 44 39 33 30 26 0 0 0 0 1 17 54 103 151 183 194 156 127 109 100 95 88 82 76 70 62 54 48 44 40 33 30 26 0 0 0 0 0 6 23 52 90 127 174 168 146 124 109 100 92 85 78 72 65 56 49 45 41 34 31 26 0 0 0 0 0 0 0 2 11 29 91 149 169 157 135 117 100 92 83 76 69 61 53 48 43 35 32 27 0

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 7 33 81 128 155 155 130 109 94 83 75 68 60 53 47 39 33 28 2

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 10 34 72 112 145 139 114 93 82 74 67 60 52 43 35 29 9

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 12 33 83 126 139 112 92 81 74 67 59 47 38 30 13

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 21 60 116 133 110 92 81 73 66 51 42 31 22

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = III

* * * TC = 0.2 HR * * *

SHEET 2 OF 10

GaSWCC

GaSWCC

Exhibit 5-III, continued: Tabular hydrograph unit discharges (csm/in) for type III rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.3 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 25 31 44 84 124 181 287 441 498 451 358 276 204 118 87 70 63 58 54 48 44 39 34 29 24 22 20 17 14 13 11 0

.10 22 28 37 56 74 108 156 244 375 457 453 389 314 180 113 83 69 62 57 51 46 41 36 31 26 23 20 18 15 13 11 0

.20 21 27 35 53 67 94 136 208 319 411 439 406 345 212 130 91 73 64 59 52 46 42 36 31 26 23 21 18 15 13 11 0

.30 19 24 30 42 49 61 83 118 178 272 365 414 409 305 190 121 87 71 63 55 49 43 38 33 27 24 21 19 15 14 11 0

.40 18 23 29 40 46 56 74 103 153 232 321 383 400 329 217 138 96 75 65 57 50 44 38 33 28 24 21 19 15 14 11 0 .50 16 21 26 34 38 43 52 67 91 132 199 280 349 383 297 196 128 91 73 60 53 46 40 35 30 25 22 20 16 14 11 0 .75 14 18 23 30 33 37 43 52 66 91 131 187 251 347 331 260 182 126 92 68 57 49 42 36 31 26 23 21 16 14 12 0 1.0 11 15 18 23 25 28 30 33 38 44 54 71 98 192 296 334 294 221 154 94 69 55 45 40 34 29 25 22 17 15 12 0

1.5 7 9 12 15 17 18 19 21 23 25 27 30 33 45 75 137 222 287 300 233 149 84 57 47 40 35 30 25 20 16 13 3

2.0 4 6 8 11 12 13 14 15 16 17 19 20 22 26 33 46 76 131 201 278 258 165 85 57 46 40 34 29 22 17 13 7

2.5 2 3 5 7 7 8 9 10 10 11 12 13 14 17 20 24 29 39 60 125 213 260 177 94 60 47 40 35 25 20 14 9

3.0 1 2 3 4 5 5 6 6 7 8 8 9 10 12 14 16 19 23 29 48 95 195 247 167 93 60 47 40 29 22 15 10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.3 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 6 22 58 146 308 424 422 367 303 234 145 111 92 84 79 74 67 62 57 50 43 36 33 30 26 22 20 17 0

.10 0 0 0 4 16 44 112 243 364 402 379 328 266 166 120 97 86 80 75 68 62 57 51 44 37 33 30 27 22 21 17 0

.20 0 0 0 3 12 33 86 190 306 370 376 344 292 189 132 103 89 82 77 69 63 58 51 44 37 34 30 27 23 21 17 0

.30 0 0 0 0 2 8 25 65 149 254 331 361 350 261 175 126 100 88 81 73 66 60 53 46 39 35 31 28 23 21 18 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

1 6 19 50 116 208 290 338 346 282 195 138 107 91 83 74 67 60 54 47 40 35 32 28 23 21 18 0 0 1 4 14 38 90 168 250 308 333 256 180 131 103 89 78 71 63 56 49 42 36 33 29 23 21 18 0 0 0 2 6 17 43 89 150 213 299 286 229 171 129 104 85 75 65 58 51 44 38 34 30 24 22 18 0 0 0 0 0 1 3 9 24 53 153 253 288 257 200 150 105 85 72 62 55 48 41 36 32 26 22 19 0

1.5 0 0 0 0 0 0 0 0 0 0 0 1 2 15 59 138 217 258 248 187 130 91 71 62 55 48 41 36 29 23 19 3

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 9 36 90 159 239 227 158 97 74 63 55 48 42 32 26 20 10

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 12 37 113 194 224 151 96 73 62 55 48 36 29 21 14

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 24 78 176 211 145 95 73 62 54 41 32 22 15

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.3 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 2 33 116 193 221 221 200 165 129 110 99 95 92 87 81 77 72 65 56 49 45 41 37 32 30 25 0

.10 0 0 0 0 0 1 23 85 157 200 214 205 178 138 115 102 96 92 88 82 77 73 66 57 50 46 42 37 32 30 26 0

.20 0 0 0 0 0 1 15 62 125 175 201 203 187 147 121 105 98 94 89 83 78 73 66 58 50 46 42 38 32 30 26 0

.30 0 0 0 0 0 0 0 10 45 99 149 184 197 174 140 117 104 97 93 86 80 75 69 61 52 47 43 39 33 30 26 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 7 32 76 125 164 189 179 148 123 107 99 94 87 81 76 69 62 53 48 44 39 33 30 26 0 0 0 0 0 5 23 59 103 144 183 169 141 119 105 98 90 84 78 71 64 55 49 45 41 33 31 26 0 0 0 0 0 2 9 27 55 89 148 168 156 135 117 105 94 87 80 73 66 58 51 46 42 34 31 27 0 0 0 0 0 0 0 1 4 14 59 119 157 163 145 126 105 95 85 77 71 63 55 49 44 36 32 27 0

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 3 19 56 103 139 151 138 116 97 85 77 70 62 54 48 40 33 28 3

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 21 52 91 135 143 120 96 84 76 69 61 54 44 35 29 11

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 7 22 65 112 136 117 96 83 75 68 60 48 39 30 18

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 13 45 102 131 114 95 83 75 67 53 43 31 22

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = III

* * * TC = 0.3 HR * * *

SHEET 3 OF 10

5-41 A-1-81

5-42 A-1-82

Exhibit 5-III, continued: Tabular hydrograph unit discharges (csm/in) for type III rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.4 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 23 29 39 65 91 132 198 308 422 449 417 345 274 162 108 82 68 61 57 50 45 41 35 30 25 22 20 18 15 13 11 0

.10 20 26 33 48 60 80 114 170 262 368 422 418 370 242 149 102 79 67 60 53 47 42 37 32 27 23 21 18 15 13 11 0

.20 20 25 32 45 55 72 100 147 224 320 388 408 383 272 171 114 85 70 62 54 48 43 37 32 27 23 21 19 15 14 11 0

.30 17 22 28 38 43 51 65 88 127 191 277 351 389 349 244 157 108 81 68 58 51 45 39 34 29 24 22 19 15 14 11 0

.40 17 21 27 36 41 47 59 79 111 165 240 314 378 359 268 178 120 88 72 60 52 45 40 34 29 25 22 20 15 14 11 0 .50 15 19 24 31 34 38 44 54 71 98 142 207 278 364 332 243 163 113 84 65 56 48 41 36 31 26 23 20 16 14 12 0 .75 12 16 20 25 27 30 33 38 44 54 70 97 138 249 333 320 257 185 131 85 65 53 44 39 33 28 24 22 17 14 12 0 1.0 11 13 17 22 23 25 28 30 34 38 46 57 75 145 245 322 311 255 188 114 77 58 47 41 35 30 26 23 18 15 12 1

1.5 6 9 11 14 15 17 18 19 21 23 25 27 30 39 59 105 180 255 292 257 176 98 61 48 41 36 31 26 20 16 13 4

2.0 4 6 8 10 11 12 13 14 15 16 17 19 20 24 30 39 61 103 166 253 272 189 98 61 48 41 35 30 23 18 13 8

2.5 2 3 4 6 7 7 8 9 10 10 11 12 13 16 18 22 26 34 49 100 183 255 198 108 66 50 42 36 26 20 14 9

3.0 1 1 2 4 4 5 5 6 6 7 8 8 9 11 13 15 18 21 26 40 77 169 243 185 106 65 49 41 30 23 15 10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.4 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 2 10 30 78 177 306 379 379 347 293 187 133 105 90 82 77 69 63 58 51 44 38 34 30 27 23 21 17 0

.10 0 0 0 2 7 22 59 138 250 336 365 353 313 212 146 112 94 84 78 71 64 59 52 45 38 34 31 27 23 21 17 0

.20 0 0 0 1 5 17 45 107 202 292 341 349 325 235 162 121 98 87 80 72 65 59 53 46 39 34 31 28 23 21 17 0

.30 0 0 0 0 1 4 12 34 83 162 249 310 336 298 215 152 116 96 85 76 68 61 55 48 41 36 32 29 23 21 18 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 3 9 26 64 130 209 276 324 307 234 168 125 101 88 77 70 62 55 49 41 36 32 29 23 21 18 0 0 0 2 7 19 49 103 173 242 313 285 216 157 119 98 82 73 65 57 51 44 37 33 30 24 22 18 0 0 0 1 3 9 23 52 97 153 253 285 253 199 151 118 91 78 68 59 53 46 39 35 31 25 22 18 0 0 0 0 0 0 1 4 13 30 104 204 276 276 226 175 120 92 75 64 57 50 43 37 33 26 22 19 1

1.5 0 0 0 0 0 0 0 0 0 0 0 0 1 8 36 98 177 236 250 207 148 99 75 63 56 49 42 37 29 24 19 4

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 22 62 124 210 232 176 107 78 65 57 50 43 33 27 20 11

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 7 24 85 167 219 167 106 77 64 56 49 37 29 21 14

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 15 58 152 207 159 104 76 64 55 42 33 22 15

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.4 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 10 54 121 182 204 204 191 146 121 106 98 94 90 83 78 73 66 58 50 46 42 38 32 30 26 0

.10 0 0 0 0 0 0 7 38 94 153 187 198 193 155 128 110 100 95 91 84 79 74 67 59 51 46 42 38 32 30 26 0

.20 0 0 0 0 0 0 5 27 71 126 166 187 191 164 134 114 103 96 92 85 80 75 68 60 52 47 43 38 33 30 26 0

.30 0 0 0 0 0 0 0 3 19 54 102 145 173 185 155 129 111 101 95 88 82 76 70 62 54 48 44 40 33 31 26 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 2 13 40 81 124 157 180 161 135 116 104 97 90 83 77 71 63 55 49 44 40 33 31 26 0 0 0 0 0 1 9 30 64 104 163 174 154 130 113 102 93 86 79 73 66 57 50 46 42 34 31 27 0 0 0 0 0 0 3 13 32 59 120 157 162 145 126 111 98 90 82 75 68 60 52 47 43 35 31 27 0 0 0 0 0 0 0 0 2 6 36 90 138 158 152 135 112 98 88 79 72 65 56 50 45 37 32 27 0

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 1 10 37 80 121 148 143 123 102 87 78 71 64 56 49 41 34 28 4

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 13 36 71 121 140 126 101 86 78 70 63 55 44 36 29 13

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 14 49 97 135 122 100 86 77 70 62 49 40 30 20

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 9 33 88 130 119 98 85 76 69 54 44 32 22

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = III

* * * TC = 0.4 HR * * *

SHEET 4 OF 10

GaSWCC

GaSWCC

Exhibit 5-III, continued: Tabular hydrograph unit discharges (csm/in) for type III rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA /P = 0.10

* * * TC = 0.5 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 21 27 35 54 70 97 144 217 316 397 411 388 330 214 139 99 78 67 60 52 47 42 36 31 26 23 21 18 15 13 11 0

.10 19 24 30 43 50 64 86 125 186 273 355 392 390 296 194 129 94 75 65 56 49 43 38 33 28 24 21 19 15 14 11 0

.20 18 23 29 40 47 58 77 109 161 235 315 367 382 318 218 145 103 80 68 57 50 44 39 33 28 24 22 19 15 14 11 0

.30 16 21 26 34 38 44 53 69 95 139 203 278 337 367 289 199 135 98 77 62 54 46 40 35 30 25 22 20 16 14 11 0

.40 16 20 25 33 36 41 49 62 84 121 176 244 306 358 306 220 151 107 83 64 55 47 41 35 30 25 23 20 16 14 12 0 .50 14 18 22 28 31 35 39 46 57 75 106 152 213 323 346 282 202 140 102 73 59 50 42 37 32 27 23 21 16 14 12 0 .75 12 16 20 25 28 30 34 38 45 56 75 104 145 246 319 308 252 187 135 89 67 53 44 39 33 28 24 22 17 14 12 0 1.0 10 12 16 20 22 23 25 28 31 34 39 47 60 110 197 280 309 279 220 138 90 63 49 42 37 31 26 23 18 15 12 1

1.5 6 8 10 13 14 15 17 18 19 21 23 25 27 34 49 82 143 218 283 271 203 116 68 51 43 37 32 27 21 16 13 4

2.0 3 5 7 9 10 11 12 13 14 15 16 17 19 22 27 34 50 82 135 226 265 211 114 67 50 42 37 31 23 18 13 8

2.5 2 3 4 6 7 7 8 9 10 10 11 12 13 16 18 22 26 34 50 102 182 249 197 111 67 50 42 36 26 20 14 9

3.0 1 1 2 3 4 4 5 5 6 6 7 8 8 10 12 14 16 19 23 34 63 144 238 201 121 72 52 43 31 23 15 10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.5 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 1 4 15 40 101 198 295 345 345 325 232 161 122 100 88 80 72 65 59 53 46 39 34 31 28 23 21 18 0

.10 0 0 0 1 3 11 30 77 158 249 313 335 329 253 178 132 106 91 82 73 66 60 53 47 40 35 31 28 23 21 18 0

.20 0 0 0 0 2 8 23 59 125 208 278 316 324 271 196 144 112 95 85 75 67 61 54 47 40 35 32 28 23 21 18 0

.30 0 0 0 0 0 2 6 17 45 98 171 242 291 313 249 182 136 108 92 80 71 63 56 49 42 36 33 29 24 21 18 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 1 4 13 34 77 140 208 264 304 263 198 148 115 97 81 72 64 57 50 43 37 33 30 24 21 18 0 0 0 1 3 10 26 60 113 177 276 295 244 185 140 111 88 77 67 59 52 45 39 34 31 24 22 18 0 0 0 0 1 4 12 29 60 104 204 271 263 222 174 136 101 83 70 61 54 47 40 35 32 25 22 18 0 0 0 0 0 0 1 2 6 16 67 155 235 263 242 198 138 102 80 66 58 51 44 38 34 27 23 19 1

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 4 22 67 138 205 241 221 167 110 79 66 58 51 44 38 30 24 20 5

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 13 42 93 182 225 191 119 83 67 58 51 44 34 27 21 12

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 15 62 139 213 180 117 82 67 58 51 38 30 22 15

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 10 41 127 203 171 114 81 66 57 43 33 23 16

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.5 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 3 24 68 124 174 190 190 162 133 114 103 97 92 85 80 75 68 60 52 47 43 39 33 30 26 0

.10 0 0 0 0 0 0 2 17 51 100 149 177 186 169 140 119 106 99 93 86 81 75 69 61 52 47 43 39 33 30 26 0

.20 0 0 0 0 0 0 1 12 38 79 126 160 181 173 147 124 109 101 95 88 81 76 69 62 53 48 44 39 33 30 26 0

.30 0 0 0 0 0 0 0 1 8 28 62 105 141 176 165 141 120 107 99 91 84 78 71 64 56 49 45 41 33 31 26 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 1 6 20 48 86 123 172 172 146 125 111 101 92 85 79 72 65 56 50 45 41 34 31 26 0 0 0 0 0 4 15 37 70 105 157 167 151 130 114 104 94 87 79 73 66 57 50 46 42 34 31 27 0 0 0 0 0 0 1 6 17 37 91 139 157 150 134 119 103 93 84 76 69 62 54 48 44 35 32 27 0 0 0 0 0 0 0 1 3 9 40 91 135 153 149 135 113 99 88 79 72 65 57 50 45 37 32 27 1

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 5 24 59 101 132 144 130 107 90 80 73 65 57 51 41 34 29 6

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 7 25 55 106 138 130 105 89 79 72 65 57 45 37 30 15

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 9 36 81 133 133 104 88 79 71 64 50 41 31 21

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 5 24 74 128 122 103 88 78 70 55 45 32 23

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = III

* * * TC = 0.5 HR * * *

SHEET 5 OF 10

5-43 A-1-83

5-44 A-1-84

Exhibit 5-III, continued: Tabular hydrograph unit discharges (csm/in) for type III rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 0.75 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 17 22 28 39 45 56 73 104 151 215 281 328 343 310 228 163 121 94 77 63 53 45 39 34 29 25 22 20 15 14 11 0

.10 17 21 27 37 42 51 66 91 131 187 250 302 336 319 247 179 131 101 82 65 55 46 40 35 29 25 22 20 16 14 11 0

.20 15 19 24 31 35 40 48 60 81 114 163 221 275 328 298 229 167 124 96 73 60 49 42 36 31 26 23 20 16 14 12 0

.30 14 18 23 30 33 38 44 55 72 100 142 194 248 320 305 245 182 135 103 76 62 50 42 37 31 27 23 21 16 14 12 0

.40 13 16 21 26 29 32 36 41 50 65 88 124 171 268 313 288 228 170 127 88 68 54 44 38 33 28 24 21 17 14 12 0 .50 12 16 20 25 28 30 34 39 46 59 78 109 150 244 306 294 242 184 138 94 71 56 45 39 34 28 24 22 17 14 12 0 .75 10 13 16 21 23 25 27 30 33 38 46 58 77 140 221 277 287 248 197 133 92 66 50 42 36 31 26 23 18 15 12 1 1.0 8 10 13 16 18 19 21 23 25 27 30 34 39 61 109 181 249 280 265 198 134 85 58 46 40 34 29 25 20 16 12 2

1.5 5 7 9 12 13 14 15 16 17 19 20 22 24 30 40 63 106 167 225 261 226 147 84 58 46 39 34 29 22 17 13 5

2.0 2 4 5 7 8 9 9 10 11 12 13 14 16 18 22 26 34 50 80 155 226 246 158 91 61 47 40 34 25 20 14 9

2.5 1 2 3 5 5 6 6 7 8 8 9 10 11 13 15 18 21 26 34 62 120 209 234 151 90 60 47 39 29 22 15 10

3.0 0 1 2 3 3 3 4 4 5 5 6 7 7 9 10 12 15 17 21 29 50 113 209 224 144 88 59 46 33 25 16 10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 0.75 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 1 3 8 24 58 113 182 243 283 287 233 178 139 114 98 83 73 64 56 50 43 37 33 30 24 21 18 0

.10 0 0 0 0 0 2 6 18 45 91 151 212 259 284 245 191 149 120 102 85 75 65 57 50 43 37 33 30 24 21 18 0

.20 0 0 0 0 0 0 1 5 14 35 72 125 183 263 277 230 180 142 116 93 80 68 59 52 45 39 34 31 25 22 18 0

.30 0 0 0 0 0 0 1 3 10 26 57 102 156 245 270 240 192 151 122 96 82 69 60 53 46 39 35 31 25 22 18 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 1 2 8 20 45 83 182 252 264 226 181 144 108 89 73 62 55 48 41 36 32 26 22 19 0 0 0 0 0 2 6 15 35 67 158 235 259 235 192 153 113 92 75 63 56 49 42 36 33 26 22 19 1 0 0 0 0 0 0 1 2 7 35 100 178 232 242 217 163 121 90 71 61 54 47 40 35 28 23 19 2 0 0 0 0 0 0 0 1 4 21 68 140 205 236 229 181 135 97 74 63 55 48 41 36 29 24 19 3

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 13 42 94 155 221 212 158 103 77 64 56 49 42 33 26 20 10

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 15 42 113 184 209 151 101 76 63 55 48 36 29 21 14

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 27 80 168 199 146 100 75 63 55 41 32 22 15

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 10 56 154 191 151 105 78 64 48 37 24 16

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 0.75 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 3 13 37 71 108 140 167 156 136 120 108 101 92 85 78 72 64 56 50 45 41 34 31 26 0

.10 0 0 0 0 0 0 0 2 10 28 57 91 124 163 158 140 124 111 103 94 86 79 72 65 57 50 46 41 34 31 27 0

.20 0 0 0 0 0 0 0 0 1 7 21 45 76 135 159 153 136 120 109 98 90 82 74 67 59 52 47 43 35 31 27 0

.30 0 0 0 0 0 0 0 0 1 5 15 35 62 121 157 157 140 124 112 100 91 83 75 68 60 52 47 43 35 31 27 0

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 1 3 11 27 50 107 146 154 143 128 115 102 93 84 76 69 61 53 48 43 35 32 27 0 0 0 0 0 0 0 2 8 21 66 118 148 152 139 125 108 97 87 78 71 63 55 49 45 36 32 27 1 0 0 0 0 0 0 1 4 10 38 82 122 142 144 133 116 103 91 80 73 66 58 51 46 37 32 28 1 0 0 0 0 0 0 0 0 0 5 24 60 102 132 142 133 116 99 86 77 70 62 55 49 40 33 28 3

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 7 25 55 91 128 136 119 98 85 77 69 62 54 44 36 29 11

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 9 25 66 109 131 116 97 85 76 69 61 48 39 30 18

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 16 47 100 127 114 96 84 75 68 53 43 31 22

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 10 44 102 124 112 95 83 75 59 47 33 23

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = III

* * * TC = 0.75 HR * * *

SHEET 6 OF 10

GaSWCC

GaSWCC

Exhibit 5-III, continued: Tabular hydrograph unit discharges (csm/in) for type III rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 1.0 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 15 19 24 32 37 44 54 71 98 136 181 227 264 297 270 215 164 128 103 78 64 52 43 36 31 26 23 21 16 14 12 0

.10 13 17 22 28 31 35 41 49 64 87 120 161 205 273 289 254 201 155 122 90 71 56 45 38 33 28 24 21 17 14 12 0

.20 13 16 21 27 29 33 38 46 58 77 105 142 184 257 285 263 214 167 130 95 74 57 46 39 33 28 24 22 17 14 12 0

.30 12 16 20 26 28 31 36 42 53 69 93 126 165 240 279 268 225 178 139 100 77 59 47 39 34 29 25 22 17 15 12 1

.40 11 14 18 23 25 27 30 34 40 48 62 83 112 185 251 276 256 213 168 118 87 65 50 41 35 30 26 23 18 15 12 1 .50 11 13 17 22 24 26 29 32 37 45 56 74 99 167 235 270 261 223 179 126 92 67 51 42 36 31 26 23 18 15 12 1 .75 8 10 13 17 18 19 21 23 25 28 31 36 44 72 122 186 239 258 243 189 136 90 62 48 40 34 29 25 20 16 12 2 1.0 6 9 11 14 15 17 18 20 21 23 25 28 32 46 75 124 185 234 253 226 170 110 71 53 43 37 31 27 21 16 13 4

1.5 4 6 8 10 11 12 13 14 15 16 17 19 21 25 32 46 74 118 170 230 239 179 108 70 52 43 36 31 23 18 13 7

2.0 2 3 4 6 7 7 8 9 10 10 11 12 13 16 18 22 28 38 58 111 179 228 185 116 75 54 44 37 27 21 14 9

2.5 1 1 2 4 4 5 5 6 6 7 8 8 9 11 13 15 18 22 28 46 87 167 219 176 113 73 54 43 31 23 15 10

3.0 0 0 1 2 2 2 3 3 3 4 4 5 5 7 8 10 12 14 16 21 32 68 156 210 179 120 78 56 37 27 16 11

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 1.0 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 1 5 13 30 57 95 141 186 243 249 213 174 142 119 97 83 70 60 53 46 39 35 31 25 22 18 0

.10 0 0 0 0 0 1 3 10 23 46 79 120 164 230 245 221 183 150 125 101 85 72 61 53 46 40 35 31 25 22 18 0

.20 0 0 0 0 0 0 1 3 7 18 36 65 102 183 233 241 210 174 144 112 92 76 64 56 48 42 36 33 26 22 19 1

.30 0 0 0 0 0 0 1 2 6 14 29 53 86 163 221 237 217 183 151 117 95 78 65 56 49 42 37 33 26 22 19 1

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 1 4 11 23 43 107 180 225 233 207 175 133 105 84 68 59 51 44 38 34 27 23 19 1 0 0 0 0 1 3 8 18 34 91 162 214 230 213 183 139 109 86 70 60 52 45 39 34 27 23 19 1 0 0 0 0 0 0 1 4 9 33 82 145 196 218 211 174 135 101 77 64 56 48 42 37 29 24 19 3 0 0 0 0 0 0 0 1 2 11 37 85 144 192 214 199 160 116 85 69 59 51 44 38 30 25 20 5

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 7 23 56 104 174 203 177 123 89 71 60 52 45 35 27 21 11

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 8 24 73 139 194 169 120 87 70 59 51 39 30 22 14

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 15 51 127 186 162 117 86 69 59 44 34 23 16

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 6 35 117 180 164 122 90 71 51 39 25 16

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 1.0 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 2 6 17 34 57 83 127 151 142 130 118 109 99 91 83 75 68 59 52 47 43 35 31 27 1

.10 0 0 0 0 0 0 0 1 5 13 27 47 71 117 146 144 133 121 112 101 92 84 76 68 60 53 48 43 35 32 27 1

.20 0 0 0 0 0 0 0 1 3 10 21 38 60 106 138 143 135 124 114 102 94 85 76 69 61 54 48 44 35 32 27 1

.30 0 0 0 0 0 0 0 0 0 2 7 16 31 73 114 139 142 132 121 108 98 88 79 71 64 56 50 45 36 32 27 1

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 2 5 13 25 62 104 133 140 134 124 110 99 89 80 72 64 56 50 45 37 32 27 1 0 0 0 0 0 0 1 4 10 35 74 112 134 138 131 117 104 93 82 74 67 59 52 47 38 33 28 2 0 0 0 0 0 0 0 2 5 19 48 84 115 131 134 123 110 97 85 77 69 61 54 48 39 33 28 3 0 0 0 0 0 0 0 0 1 6 21 49 84 113 129 132 119 103 89 80 72 64 56 50 41 34 28 5

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 7 21 46 75 113 128 120 102 88 79 71 63 56 45 37 29 12

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 14 42 82 119 124 104 90 80 72 64 50 41 31 20

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 9 29 75 117 121 102 89 79 71 56 45 32 23

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 28 80 118 118 101 88 79 63 49 34 24

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = III

* * * TC = 1.0 HR * * *

SHEET 7 OF 10

5-45 A-1-85

5-46 A-1-86

Exhibit 5-III, continued: Tabular hydrograph unit discharges (csm/in) for type III rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 1.25 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 13 17 22 28 32 37 44 56 75 100 133 170 206 255 264 236 194 155 125 95 75 59 47 39 33 28 24 22 17 14 12 1

.10 13 16 21 27 30 34 41 51 67 89 118 152 188 243 261 243 204 164 133 100 79 61 48 40 34 29 25 22 17 15 12 1

.20 11 15 18 24 26 29 33 38 47 60 79 105 137 203 248 256 232 193 156 115 88 67 51 42 35 30 26 23 18 15 12 1

.30 11 14 18 23 25 27 31 36 43 54 71 94 122 187 237 254 238 203 165 121 92 69 53 43 36 30 26 23 18 15 12 1

.40 10 12 16 20 22 24 26 29 34 40 49 64 84 140 201 242 250 228 193 142 106 77 57 46 38 32 27 24 19 15 12 1 .50 9 12 15 19 21 23 25 28 32 37 45 58 75 126 186 232 248 233 201 150 111 80 58 47 39 33 28 24 19 15 12 2 .75 8 11 14 17 19 20 22 24 27 31 36 44 56 93 144 196 230 237 220 174 131 91 64 50 41 34 29 25 20 16 12 2 1.0 6 8 11 14 15 16 17 19 20 22 25 28 32 46 74 119 170 213 234 218 174 120 79 58 46 38 32 27 21 17 13 4

1.5 3 5 7 9 9 10 11 12 13 14 16 17 18 22 27 38 58 91 134 197 223 194 128 83 60 47 39 33 24 19 14 7

2.0 2 3 4 6 6 7 8 8 9 10 11 12 13 15 18 22 27 38 57 106 166 214 184 124 82 59 47 39 28 21 14 9

2.5 1 1 2 3 3 4 4 5 5 6 7 7 8 10 11 13 16 19 24 38 68 137 206 186 130 87 62 48 33 24 15 10

3.0 0 0 1 2 2 2 2 3 3 4 4 5 5 6 8 9 11 13 16 21 31 66 145 200 178 126 85 61 39 28 17 11

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 1.25 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 1 2 7 18 35 61 94 130 192 222 218 191 161 136 110 93 77 65 56 48 41 36 32 26 22 19 1

.10 0 0 0 0 0 1 2 5 14 28 50 79 113 177 214 219 197 168 142 115 96 79 66 57 49 42 37 33 26 22 19 1

.20 0 0 0 0 0 0 1 4 10 22 41 66 97 162 205 217 202 175 149 119 99 81 67 58 50 43 37 33 26 23 19 1

.30 0 0 0 0 0 0 0 1 3 8 17 33 55 115 174 208 214 195 168 133 108 87 70 60 52 45 39 34 27 23 19 2

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 1 2 6 14 26 45 100 159 200 212 199 174 138 112 89 72 61 53 45 39 35 28 23 19 2 0 0 0 0 1 2 5 11 21 60 116 170 203 209 192 156 124 97 76 64 55 47 41 36 29 24 19 3 0 0 0 0 0 1 2 5 11 35 79 131 175 201 201 172 140 107 82 67 58 50 43 37 30 24 20 4 0 0 0 0 0 0 0 0 1 6 23 57 105 153 186 198 172 131 95 75 63 54 47 41 32 25 20 7

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 8 24 54 96 157 189 174 127 94 74 63 54 46 35 28 21 12

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 9 24 69 127 182 167 124 93 74 62 53 40 31 22 15

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 10 35 99 176 167 129 96 76 63 46 35 23 16

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 6 34 107 171 161 125 94 75 53 40 25 17

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 1.25 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 1 4 10 21 36 55 95 123 138 131 122 114 104 95 86 78 70 62 55 49 44 36 32 27 1

.10 c 0 c 0 0 0 0 0 1 3 8 16 30 66 102 125 134 128 120 108 99 89 80 73 65 57 51 46 37 32 28 2

.20 0 0 0 0 0 0 0 0 0 2 6 13 24 57 94 120 132 130 122 110 101 91 81 73 66 58 51 46 37 33 28 2

.30 0 0 0 0 0 0 0 0 0 1 4 10 19 49 85 113 131 131 124 112 102 92 82 74 66 58 52 47 38 33 28 2

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 1 3 8 16 42 76 106 126 130 125 114 104 93 83 75 67 59 52 47 38 33 28 3 0 0 0 0 0 0 1 2 6 22 51 84 112 127 129 120 109 97 86 77 70 61 54 49 40 33 28 4 0 0 0 0 0 0 0 1 3 12 32 61 91 113 125 123 114 101 89 80 72 64 56 50 41 34 28 5 0 0 0 0 0 0 0 0 0 1 7 22 47 76 102 122 124 111 96 85 76 69 61 54 43 36 29 9

1.5 c 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 8 22 43 82 111 121 109 95 84 76 68 60 48 39 30 16

2.0 0 0 c 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 9 30 63 104 118 107 94 83 75 67 53 43 31 21

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 6 20 58 104 116 106 93 83 74 59 47 33 23

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 19 64 104 114 104 92 82 65 52 35 24

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = III

* * * TC = 1.25 HR * * *

SHEET 8 OF 10

GaSWCC

GaSWCC

Exhibit 5-III, continued: Tabular hydrograph unit discharges (csm/in) for type III rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 1.5 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 12 15 19 25 27 31 37 45 57 75 97 122 151 203 231 238 213 182 150 115 91 70 54 44 37 30 26 23 18 15 12 1

.10 10 13 17 21 23 26 29 34 41 52 67 87 111 165 210 233 227 205 173 131 102 77 58 46 39 32 27 24 19 15 12 1

.20 10 13 16 21 23 25 28 32 38 47 61 78 100 152 199 228 231 210 181 138 107 80 59 47 39 33 28 24 19 15 12 2

.30 9 12 15 20 22 24 27 30 36 44 55 70 90 139 188 221 228 215 188 145 112 83 61 48 40 33 28 24 19 15 12 2

.40 8 11 14 18 19 21 23 25 29 33 40 50 64 103 152 196 223 226 208 166 127 92 66 52 42 35 30 25 20 16 13 2 .50 8 10 13 17 18 20 22 24 27 31 37 46 58 93 140 186 216 224 212 173 133 96 69 53 43 36 30 26 20 16 13 3 .75 6 8 11 14 15 16 18 19 21 23 26 31 36 55 87 130 173 205 217 202 165 119 81 60 48 39 33 28 21 17 13 4 1.0 5 6 8 11 12 13 14 15 16 18 19 21 24 31 46 71 109 151 189 214 200 153 102 72 55 44 37 31 23 18 13 6

1.5 3 4 5 7 8 9 10 11 11 12 14 15 16 19 24 31 45 69 103 159 207 207 147 99 71 54 44 36 26 20 14 8

2.0 1 2 3 5 5 6 6 7 8 9 9 10 11 13 16 19 23 31 45 81 132 189 199 142 97 69 53 43 30 22 15 10

2.5 0 1 1 2 3 3 4 4 4 5 6 6 7 8 10 12 14 17 20 31 53 107 179 194 147 102 73 55 36 26 16 10

3.0 0 0 1 1 1 2 2 2 3 3 3 4 4 5 7 8 10 11 13 18 26 51 116 178 188 142 100 71 43 30 18 11

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 1.5 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 1 2 5 11 22 38 59 84 138 180 200 195 176 154 125 105 86 71 60 52 44 39 34 27 23 19 2

.10 0 0 0 0 0 0 0 1 4 9 18 31 50 99 149 184 198 190 170 139 115 93 75 63 55 47 40 35 28 23 19 3

.20 0 0 0 0 0 0 0 1 3 7 14 25 41 86 137 176 195 192 175 144 119 95 76 64 55 47 41 36 28 24 19 3

.30 0 0 0 0 0 0 0 0 1 2 5 11 21 53 100 147 181 194 187 159 130 103 81 68 58 50 43 37 29 24 19 4

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 2 4 9 17 45 88 136 172 192 189 164 135 106 83 69 59 51 43 38 30 24 20 4 0 0 0 0 0 0 1 3 7 23 56 101 145 177 190 177 149 116 89 73 62 53 45 39 31 25 20 6 0 0 0 0 0 0 0 1 3 13 35 71 113 151 176 184 162 128 97 77 65 55 48 41 32 26 20 7 0 0 0 0 0 0 0 0 0 2 8 24 53 92 132 174 182 153 114 88 72 61 52 45 34 27 21 10

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 9 24 50 103 152 175 148 112 87 71 60 51 38 30 22 14

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 24 62 127 170 151 116 89 73 61 45 34 23 16

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 16 58 131 165 146 113 88 72 52 39 25 16

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 16 67 134 161 142 111 87 60 44 27 17

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 1.5 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 1 2 6 13 22 34 65 94 114 129 122 117 108 100 91 81 74 66 58 52 46 38 33 28 2

.10 0 0 0 0 0 0 0 0 0 2 5 10 18 42 73 99 116 126 121 112 104 94 84 76 68 60 53 48 39 33 28 3

.20 0 0 0 0 0 0 0 0 0 1 4 8 15 36 65 93 112 123 122 113 105 95 85 77 69 61 54 48 39 34 28 4

.30 0 0 0 0 0 0 0 0 0 0 1 3 6 20 44 72 97 114 122 118 109 99 88 79 71 63 56 50 41 34 28 5

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 0 1 2 5 16 38 65 91 110 121 119 110 100 89 80 72 64 57 51 41 34 29 5 0 0 0 0 0 0 0 1 4 13 33 59 85 105 118 120 112 101 90 81 73 65 57 51 41 35 29 6 0 0 0 0 0 0 0 1 2 7 20 41 66 89 107 118 115 105 93 83 75 67 60 53 43 35 29 8 0 0 0 0 0 0 0 0 0 1 4 14 31 53 78 106 117 113 100 89 80 72 64 57 46 37 30 12

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 14 29 60 91 115 111 99 88 79 71 63 50 41 31 18

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 20 45 85 113 109 98 87 78 70 56 45 32 22

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 13 42 87 111 107 97 86 78 62 49 34 24

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 9 39 82 109 109 98 87 70 56 37 25

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = III

* * * TC = 1.5 HR * * *

SHEET 9 OF 10

5-47 A-1-87

5-48 A-1-88

Exhibit 5-III, continued: Tabular hydrograph unit discharges (csm/in) for type III rainfall distribution

(210-VI-TR-55, Second Ed., June 1986)

TRVL---------------------------------------------------------------------------------------------------------HYDROGRAPH TIME (HOURS)----------------------------------------------------------------------------------------------------

TIME

11.3

11.9

12.1

12.3

12.5

12.7

13.0

13.4

13.8

14.3

15.0

16.0

17.0

18.0

20.0

26.0

(HR) 11.0

11.6

12.0

12.2

12.4

12.6

12.8

13.2

13.6

14.0

14.6

15.5

16.5

17.5

19.0

22.0

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.10

* * * TC = 2.0 HR * * *

IA/P = 0.10

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 9 11 15 19 21 23 27 31 39 48 60 75 91 129 164 187 200 191 178 147 119 92 69 55 45 37 31 26 20 16 13 3

.10 8 10 13 17 18 20 22 25 29 36 44 55 68 101 139 170 189 197 188 163 132 101 75 59 47 39 33 28 21 17 13 3

.20 7 10 13 16 18 19 21 24 28 33 40 50 62 93 129 162 185 195 190 168 137 104 77 60 48 40 33 28 21 17 13 4

.30 7 9 12 15 17 18 20 23 26 31 37 46 56 85 120 154 179 193 191 172 142 108 80 62 49 41 34 29 21 17 13 4

.40 6 8 11 14 15 16 18 19 22 25 29 34 42 64 94 129 161 183 192 183 157 120 87 66 53 43 36 30 22 17 13 5 .50 6 8 10 13 14 16 17 19 21 23 27 32 38 58 87 121 153 177 191 185 162 124 90 68 54 44 36 31 22 18 13 5 .75 5 6 8 11 12 13 14 15 16 18 20 23 26 37 55 81 113 144 169 186 179 147 106 78 61 49 40 33 24 19 14 6 1.0 4 5 7 9 10 11 12 13 14 15 17 18 20 27 38 56 82 113 143 176 185 164 121 88 67 53 43 36 26 20 14 7

1.5 2 3 4 5 6 7 7 8 9 10 10 11 12 15 18 23 31 45 65 106 148 180 166 126 92 69 55 44 31 23 15 9

2.0 1 1 2 3 4 4 5 5 6 6 7 8 8 10 12 14 18 23 31 52 87 139 176 160 122 90 68 54 36 26 16 10

2.5 0 0 1 2 2 2 2 3 3 4 4 5 5 6 7 9 11 13 16 22 36 71 132 172 161 126 94 71 45 31 18 11

3.0 0 0 0 1 1 1 1 1 2 2 2 3 3 4 5 6 7 9 10 14 19 35 78 136 168 156 123 92 54 36 20 11

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.30

* * * TC = 2.0 HR * * *

IA/P = 0.30

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 1 2 6 11 18 29 41 75 111 140 159 170 163 145 124 103 84 70 60 51 44 39 30 25 20 4

.10 0 0 0 0 0 0 0 1 2 4 9 15 24 50 84 118 145 160 167 155 134 110 89 74 63 54 46 40 31 25 20 5

.20 0 0 0 0 0 0 0 0 1 3 7 12 20 43 76 110 138 157 165 157 138 113 91 75 64 55 47 41 32 26 20 5

.30 0 0 0 0 0 0 0 0 1 3 5 10 17 38 68 101 131 152 164 159 141 116 93 77 65 56 48 41 32 26 20 6

.40 0 0 0 0 .50 0 0 0 0 .75 0 0 0 0 1.0 0 0 0 0

0 0 0 0 0 1 2 4 8 22 45 76 109 137 155 163 151 125 99 81 68 58 50 43 33 26 20 7 0 0 0 0 0 1 1 3 7 18 39 69 101 130 151 162 153 128 101 83 69 59 51 44 34 27 20 7 0 0 0 0 0 0 0 1 2 6 17 36 63 93 122 151 158 143 114 92 76 64 55 47 36 28 21 9 0 0 0 0 0 0 0 0 0 2 7 18 37 63 93 132 157 153 125 100 82 68 58 50 38 29 21 11

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 12 26 59 100 142 154 128 102 83 70 59 44 34 23 15

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 18 43 93 142 150 125 101 82 69 50 38 24 16

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 12 41 98 141 147 122 99 81 58 43 26 17

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 8 38 92 135 144 124 102 69 50 30 18

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

IA/P = 0.50

* * * TC = 2.0 HR * * *

IA/P = 0.50

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

0.0 0 0 0 0 0 0 0 0 1 3 6 11 16 33 54 75 91 102 114 114 103 96 87 79 72 64 57 51 41 35 29 6

.10 0 0 0 0 0 0 0 0 1 2 5 9 14 29 49 70 87 99 106 113 104 97 88 80 72 65 58 52 42 35 29 6

.20 0 0 0 0 0 0 0 0 0 1 2 4 7 18 34 54 74 90 101 112 107 99 90 82 75 67 60 53 43 36 29 8

.30 0 0 0 0 0 0 0 0 0 0 1 3 6 15 30 49 69 86 98 111 108 100 91 83 75 68 60 54 43 36 29 8

.40 0 0 0 0 0 0 0 0 0 0 0 1 2 8 19 35 55 73 89 105 110 103 94 86 78 70 62 56 45 37 30 10

.50 0 0 0 0 0 0 0 0 0 0 0 1 2 6 16 31 50 69 85 102 109 104 95 86 78 71 63 56 45 37 30 11

.75 0 0 0 0 0 0 0 0 0 0 0 0 1 4 10 21 37 55 73 93 107 107 97 89 81 73 65 58 47 38 30 13

1.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 7 15 29 46 72 93 107 103 94 86 78 70 62 50 40 31 16

1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 7 15 34 59 89 105 101 93 85 77 69 55 44 32 21

2.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 10 25 55 90 104 100 92 84 76 61 49 34 23

2.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 7 24 59 91 103 99 91 83 68 54 36 25

3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 7 28 62 91 101 98 90 75 60 39 26

---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---

RAINFALL TYPE = III

* * * TC = 2.0 HR * * *

SHEET 10 OF 10

GaSWCC

Chapter 6: Storage volume for detention basins

As rural areas become urbanized, the resulting increases in peak discharges can adversely affect downstream flood plains. Increasingly, planners, developers, and the public want these downstream areas to be protected. Many local governments are adopting ordinances to control the type of development and its allowable impacts on the watershed. One of the most common controls requires that postdevelopment discharges do not exceed present-condition discharges for one or more storm frequencies at specified points along a channel.
This chapter discusses ways to manage peak discharges by delaying runoff. It also presents a procedure for estimating the storage capacity required to maintain the peaks within a specified level.
Efforts to reduce the effects of increased runoff from urban areas have been innovative and diverse. Many methods have been used effectively, such as infiltration trenches, porous pavement, rooftop storage, and cisterns. But these solutions can be expensive or require site conditions that cannot be provided.
The detention basin is the most widely used measure for controlling peak discharge. It is generally the least expensive and most reliable of the measures that have been considered. It can be designed to fit a wide variety of sites and can accommodate multiple-outlet spillways to meet requirements for multifrequency control of outflow. Measures other than a detention basin may be preferred in some locations; their omission here is not intended to discourage their use. Any device selected, however, should be assessed as to its function, maintenance needs, and impact.
Estimating the effect of storage
When a detention basin is installed, hydraulic routing procedures can be used to estimate the effect on hydrographs. Both the TR-20 (SCS 1983) and DAMS2 (SCS 1982) computer programs provide accurate methods of analysis. Programmable calculator and computer programs are available for routing hydrographs through dams.
This chapter contains a manual method for quick estimates of the effects of temporary detention on peak discharges. The method is based on average storage and routing effects for many structures.

Figure 6-1 relates two ratios: peak outflow to peak inflow discharge (qo/qi) and storage volume to runoff volume (Vs/Vr) for all four rainfall distributions.
The relationships in figure 6-1 were determined on the basis of single stage outflow devices. Some were controlled by pipe flow, others by weir flow. Verification runs were made using multiple stage outflow devices, and the variance was similar to that in the base data. The method can therefore be used for both single- and multiple-stage outflow devices. The only constraints are that (1) each stage requires a design storm and a computation of the storage required for it and (2) the discharge of the upper stage(s) includes the discharge of the lower stage(s).
The brevity of the procedure allows the planner to examine many combinations of detention basins. When combined with the Tabular Hydrograph method, the procedure's usefulness is increased. Its principal use is to develop preliminary indications of storage adequacy and to allocate control to a group of detention basins. It is also adequate, however, for final design of small detention basins.
Input requirements and procedures
Use figure 6-1 to estimate storage volume (Vs) required or peak outflow discharge (qo). The most frequent application is to estimate Vs, for which the required inputs are runoff volume (Vr), qo, and peak inflow discharge (qi). To estimate qo, the required inputs are Vr, Vs, and qi.
Estimating Vs
Use worksheet 6a to estimate Vs, storage volume required, by the following procedure.
1. Determine qo. Many factors may dictate the selection of peak outflow discharge. The most common is to limit downstream discharges to a desired level, such as predevelopment discharge. Another factor may be that the outflow device has already been selected.
2. Estimate qi by procedures in chapters 4 or 5. Do not use peak discharges developed by any other procedure. When using the Tabular Hydrograph method to estimate qi for a subarea, only use peak discharge associated with Tt = 0.

GaSWCC

(210-VI-TR-55, Second Ed., June 1986)

6-1 A-1-89

(VVrs)

Storage volume Runoff volume

.6 .5

.4
Types II & III .3
Types I & IA .2

.1

.1

.2

.3

.4

.5

.6

.7

.8

Peak outflow discharge Peak inflow discharge

(qqoi )

Figure 6-1. - Approximate Detention Basin Routing for Rainfall Types I, IA, II, and III

6-2 A-1-90

(210-VI-TR-55, Second Ed., June 1986)

GaSWCC

3. Compute qo/qi and determine Vs/Vr from figure 6-1.
4. Q (in inches) was determined when comput-
ing qi in step 2, but now it must be converted to the units in which Vs is to be expressed most likely, acre-feet or cubic feet. The most
common conversion of Q to Vr is expressed in acre-feet:

where

Vr = 53.33Q(Am)

[Eq. 6-1]

Vr = runoff volume (acre-ft), Q = runoff (in),
A = drainage area (mi2), and m
53.33 = conversion factor from in-mi2 to acre-ft.

5. Use the results of steps 3 and 4 to compute Vs:

Vs=Vr

Vs Vr

[Eq. 6-2]

where V = storage volume required (acre-ft). s
6. The stage in the detention basin correspond-
ing to Vs must be equal to the stage used to generate qo. In most situations a minor modification of the outflow device can be made. If
the outflow device has been preselected, re-
peat the calculations with a modified qo value.

Estimating q o

Use worksheet 6b to estimate qo, required peak outflow discharge, by the following procedure.

1. Determine V . If the maximum stage in the des tention basin is constrained, set Vs by the

maximum permissible stage.

2. Compute Q (in inches) by the procedures in

chapter 2, and convert it to the same units as

V (see step 4 in "Estimating V ").

s

s

3. Compute Vs/Vr and determine qo/qi from fig-

ure 6-1.

4. Estimate q by the procedures in chapters 4 i or 5. Do not use peak discharges developed

by any other method. When using the Tabular

method to estimate qi for a subarea, use only the peak discharge associated with Tt = 0. 5. From steps 3 and 4, compute q :
o

qo=qi

qo qi

[Eq. 6-3]

6. Proportion the outflow device so that the stage

at qo is equal to the stage corresponding to

V . If q cannot be calibrated except in dis-

s

o

crete steps (i.e., pipe sizes), repeat the pro-

cedure until the stages for qo and Vs are approximately equal.

Limitations



This routing method is less accurate as the q /q oi

ratio approaches the limits shown in figure 6-1. The

curves in figure 6-1 depend on the relationship

between available storage, outflow device, inflow

volume, and shape of the inflow hydrograph. When

storage volume (V ) required is small, the shape of s
the outflow hydrograph is sensitive to the rate of

rise of the inflow hydrograph. Conversely, when Vs is large, the inflow hydrograph shape has little ef-

fect on the outflow hydrograph. In such instances,

the outflow hydrograph is controlled by the hydrau-

lics of the outflow device and the procedure there-

fore yields consistent results. When the peak out-

flow discharge (q ) approaches the peak inflow diso
charge (qi), parameters that affect the rate of rise of a hydrograph, such as rainfall volume, curve

number, and time of concentration, become espe-

cially significant.

The procedure should not be used to perform final design if an error in storage of 25 percent cannot be tolerated. Figure 6-1 is biased to prevent undersizing of outflow devices, but it may significantly overestimate the required storage capacity. More detailed hydrograph development and routing will often pay for itself through reduced construction costs.

Examples

Four examples illustrate the use of figure 6-1. Examples 6-1 through 6-4, respectively, show estimation of Vs, use of a two-stage structure, estimation of qo, and use with the Tabular Hydrograph method.

Example 6-1: Estimating Vs, single-stage structure
A development is being planned in a 75-acre (0.117mi2) watershed that outlets into an existing concretelined channel designed for present conditions. If the channel capacity is exceeded, damages will be substantial. The watershed is in the type II storm distribution region. The present channel capacity, 180 cfs, was established by computing discharge for the 25-year-frequency storm by the Graphical Peak Discharge method (chapter 4).

GaSWCC

(210-VI-TR-55, Second Ed., June 1986)

6-3 A-1-91

The developed-condition peak discharge (qi) computed by the same method is 360 cfs, and runoff (Q) is 3.4 inches. Since outflow must be held to 180 cfs, a detention basin having that maximum outflow discharge (qo) will be built at the watershed outlet.
How much storage (Vs) will be required to meet the maximum outflow discharge (qo) of 180 cfs, and what will be the approximate dimensions of a rectangular weir outflow structure? Figure 6-2 shows how worksheet 6a is used to estimate required storage (Vs = 5.9 acre-ft) and maximum stage (Emax = 105.7 ft).
The rectangular weir was chosen for its simplicity; however, several types of outlets can meet the outflow device proportion requirement. Most hydraulic references, along with considerable research data that are available, provide more guidance on variations of outlet devices than can be summarized here.

An outlet device should be proportioned to meet specific objectives. A single-stage device was specified in this example because only one storm was considered. A weir is suitable here because of the low head. The weir crest elevation is 100.0 ft.

Using Vs = 5.9 acre-ft (figure 6-2, step 9) and the elevation-storage curve, the maximum stage (Emax) is 105.7 ft.

The rectangular weir equation is

qo = 3.2 LwHw1.5

where
qo = peak outflow discharge (cfs), L = weir crest length (ft), and
w
Hw = head over weir crest (ft).

Hw and qo are computed as follows:

H = E - weir crest elevation

w

max

= 105.7 - 100.0 = 5.7 ft.

[Eq. 6-4]

Since qo is known to be 180 cfs, solving equation 64 for Lw yields

Lw =

qo

3.2

H 1.5 w

= 180 = 4.1 ft. 3.2 (5.7)1.5

[Eq. 6-5]

In summary, the outlet structure is a rectangular weir with crest length of 4.1 ft, Hw= 5.7 ft, and qo = 180 cfs corresponding to a Vs = 5.9 acre-ft.

6-4 A-1-92

(210-VI-TR-55, Second Ed., June 1986)

GaSWCC

GaSWCC

Figure 6-2. - Worksheet 6a for Example 6-1 (210-VI-TR-55, Second Ed., June 1986)

6-5 A-1-93

Example 6-2: Estimating Vs, two-stage structure
In addition to the requirements for a 25-year peak outflow discharge of 180 cfs stated in example 6-1, a decision was made to limit the 2-year outflow discharge to 50 cfs because of potential damages to agricultural property below the lined channel. By the method in chapter 4, the estimated 2-year peak discharge for developed conditions will be 91 cfs and runoff (Q) will be 1.5 inches.
Again, a rectangular concrete weir outflow device was selected; the device could have been another type, but it is important to remember that the flows through the first stage are part of the total discharge of the higher stage.
Figure 6-3 shows how worksheet 6a is used to compute the Vs of 2.4 acre-ft and Emax of 103.6 for the first stage. Emax of 103.6 is the weir crest elevation for the second stage.
Equation 6-5 is again used to compute Lw for the first stage. The weir crest elevation for the first stage is 100.00 ft and qo = 50 cfs. The first-stage computations for Hw and Lw are
Hw = Emax - weir crest elevation = 103.6 - 100.0 = 3.6 ft;
and, from equation 6-5,
Lw = 50 = 2.3 ft. 3.2(3.6)1.5
The second stage is then proportioned to discharge the correct amount at 105.7 ft (figure 6-2, step 10). Compute the discharge through the first stage for elevation 105.7 ft using
Lw = 2.3 ft (first stage)
and
Hw = 105.7 - 100.0 = 5.7 ft.

By substituting these values in equation 6-4, discharge (qo) through the first stage at 105.7 ft is calculated:
qo = 3.2(2.3)(5.7)1.5 = 100 cfs.
Now compute the required weir crest length (Lw) for the second stage, using equation 6-5. Since the second stage crest elevation is 103.6 ft,
Hw = 105.7 - 103.6 = 2.1 ft;
and, since qo for the second stage equals the total discharge from example 6-1 minus discharge through the first stage,
qo = 180 - 100 = 80 cfs.
Finally, substituting these Hw and qo values in equation 6-5 results in
Lw = 80 = 8.2 ft. 3.2(2.1)1.5
In summary, the outlet structure is a 2-stage rectangular weir with first stage crest length of 2.3 ft at elevation 100.0, and second stage crest length of 8.2 ft at elevation 103.6 ft.
The weir equation used is probably less accurate for the two-stage example than for the single-stage example. The actual second-stage discharge will be slightly more than the one computed, but a discussion of hydraulics of outflow devices is outside the scope of this technical release. Example 6-2 is presented only to illustrate the interrelationship of outflow discharges and storage volume and to show how to develop preliminary estimates of storage requirements for two-stage outlet structures.

6-6 A-1-94

(210-VI-TR-55, Second Ed., June 1986)

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Figure 6-3. - Worksheet 6a for Example 6-2 (210-VI-TR-55, Second Ed., June 1986)

6-7 A-1-95

Example 6-3: Estimating qo
A development is being planned for a 10-acre watershed (0.0156 mi2). A county ordinance requires that the developed-condition outflow from the watershed for a 24-hr, 100-year frequency storm does not exceed the outflow for present conditions. The peak discharge from the watershed for present conditions, 35 cfs, is calculated from procedures in chapter 4. For developed conditions, runoff (Q) is 5.4 inches, peak discharge from the watershed is 42 cfs from procedures in chapter 4, and rainfall distribution is type II.
What will be the peak outflow discharge (qo) from a detention basin that is located at the outlet and has maximum allowable storage volume (Vs) of 35,000 ft3 and peak inflow discharge (qi) of 42 cfs? Figure 6-4 shows how worksheet 6b is used to estimate qo as 33 cfs, which is within the 35-cfs limit. An outflow device will be selected to discharge 33 cfs at a stage corresponding to a Vs of 35,000 ft3.

6-8 A-1-96

(210-VI-TR-55, Second Ed., June 1986)

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Figure 6-4. - Worksheet 6b for Example 6-3 (210-VI-TR-55, Second Ed., June 1986)

6-9 A-1-97

Example 6-4: Estimating Vs, Tabular Hydrograph method

This example builds on examples 5-1 and 5-2 (pages 5-4 to 5-8). If peak outflow discharge from subarea 7 must not exceed the discharge for present conditions, what will be the storage volume (Vs) required in a detention basin at the outlet of subarea 6?

First, compute the outflow hydrograph without subarea 6 as shown in the table below, which presents developed-condition discharges for example 5-2. (The information in the table is from figure 5-4.)
Discharge (cfs) at time (hr)-

Subarea

13.0 13.2 13.4 13.6 13.8 14.0 14.3 14.6 15.0

1 2 3 4 5 6 omitted 7 Total without subarea 6

--------------------------cfs----------------------------7 9 11 16 24 40 78 122 155 7 9 12 20 33 55 96 132 132
14 29 58 89 106 102 74 46 25 19 32 63 114 169 207 193 143 83 117 167 205 214 202 175 132 99 70
--------244 167 119 90 72 59 48 40 34 408 413 468 543 606 638 621 582 499

The required storage volume of 33.2 acre-ft is the basis for determining the required stage in the detention basin. This stage is a guide in proportioning a spillway that will discharge 82 cfs or less at that storage. The timing or routing effect is not considered because the outflow hydrograph will discharge at near qo for a significant period.

After computing the outflow hydrograph, determine the maximum permissible outflow discharge from subarea 6. The present condition peak discharge at the outlet of subarea 7 is 720 cfs at 14.3 hr (figure 5-2), and the developed condition peak discharge at the outlet of subarea 7 minus subarea 6 is 638 cfs (table above). The difference between these two discharges, 82 cfs, is the maximum outflow discharge (qo) for the detention basin.

Next, determine the peak discharge for subarea 6 for developed conditions by substituting values in equation 5-1:

q = qt AmQ.

[Eq. 5-1]

From exhibit 5-II, the largest qt value is 357 csm/in (exhibit 5-II, sheet 7: Tc = 1.0 hr, Tt = 0, and Ia/P = 0.10 at 12.8 hr). From figure 5-4, AmQ for subarea 6 is 1.31. Therefore,

q = (357) (1.31) = 468 cfs.

This q value is, of course, the same as the peak inflow discharge (qi) into the detention basin.
Finally, use worksheet 6a (figure 6-5) to compute Vs as 33.2 acre-ft.

6-10 A-1-98

(210-VI-TR-55, Second Ed., June 1986)

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Figure 6-5. - Worksheet 6a for Example 6-4 (210-VI-TR-55, Second Ed., June 1986)

6-11 A-1-99

A-1-100

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Appendix A: Hydrologic soil groups

Soils are classified into hydrologic soil groups (HSG's) to indicate the minimum rate of infiltration obtained for hare soil after prolonged wetting. The HSG's, which are A, B, C, and D, are one element used in determining runoff curve numbers (see chapter 2). For the convenience of TR-55 users, exhibit A-l lists the HSG classification of United States soils.
The infiltration rate is the rate at which water enters the soil at the soil surface. It is controlled by surface conditions. HSG also indicates the transmission ratethe rate at which the water moves within the soil. This rate is controlled by the soil profile. Approximate numerical ranges for transmission rates shown in the HSG definitions were first published by Musgrave (USDA 1955). The four groups are defined by SCS soil scientists as follows:
Group A soils have low runoff potential and high infiltration rates even when thoroughly wetted. They consist chiefly of deep, well to excessively drained sands or gravels and have a high rate of water transmission (greater than 0.30 in/hr).
Group B soils have moderate infiltration rates when thoroughly wetted and consist chiefly of moderately deep to deep, moderately well to well drained soils with moderately fine to moderately coarse textures. These soils have a moderate rate of water transmission (0.15 - 0.30 in/hr).
Group C soils have low infiltration rates when thoroughly wetted and consist chiefly of soils with a layer that impedes downward movement of water and soils with moderately fine to fine texture. These soils have a low rate of water transmission (0.05 - 0.15 in/hr).
Group D soils have high runoff potential. They have very low infiltration rates when thoroughly wetted and consist chiefly of clay soils with a high swelling potential, soils with a permanent high water table, soils with a claypan or clay layer at or near the surface, and shallow soils over nearly impervious material. These soils have a very low rate of water transmission (0 - 0.05 in/hr).

Disturbed soil profiles
As a result of urbanization, the soil profile may be considerably altered and the listed group classification may no longer apply. In these circumstances, use the following to determine HSG according to the texture of the new surface soil, provided that significant compaction has not occurred (Brakensiek and Rawls 1983):
HSG Soil textures
A Sand, loamy sand, or sandy loam B Silt loam or loam C Sandy clay loam D Clay loam, silty clay loam, sandy clay, silty clay,
or clay
Drainage and group D soils
Some soils in the list are in group D because of a high water table that creates a drainage problem. Once these soils are effectively drained, they are placed in a different group. For example, Ackerman soil is classified as A/D. This indicates that the drained Ackerman soil is in group A and the undrained soil is in group D.
Note: See the Manual for Erosion and Sediment Control in Georgia. Appendix B-l, for list of soils.

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(210-VI-TR-55, Second Ed., June 1986)

A-1 A-1-101

A-1-102

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Appendix B: Synthetic rainfall distributions and rainfall data sources

The highest peak discharges from small watersheds in the United States are usually caused by intense, brief rainfalls that may occur as distinct events or as part of a longer storm. These intense rainstorms do not usually extend over a large area and intensities vary greatly. One common practice in rainfall-runoff analysis is to develop a synthetic rainfall distribution to use in lieu of actual storm events.This distribution includes maximum rainfall intensities for the selected design frequency arranged in a sequence that is critical for producing peak runoff.
Synthetic rainfall distributions
The length of the most intense rainfall period contributing to the peak runoff rate is related to the time of concentration (Tc) for the watershed. In a hydrograph created with SCS procedures, the duration of rainfall that directly contributes to the peak is about 170 percent of the Tc. For example, the most intense 8.5-minute rainfall period would contribute to the peak discharge for a watershed with a Tc of 5 minutes; the most intense 8.5-hour period would contribute to the peak for a watershed with a 5-hour Tc.
Different rainfall distributions can be developed for each of these watersheds to emphasize the critical rainfall duration for the peak discharges. However, to avoid the use of a different set of rainfall intensities for each drainage area size, a set of synthetic rainfall distributions having "nested" rainfall intensities was developed. The set "maximizes" the rainfall intensities by incorporating selected short duration intensities within those needed for longer durations at the same probability level.
For the size of the drainage areas for which SCS usually provides assistance, a storm period of 24 hours was chosen for the synthetic rainfall distributions. The 24-hour storm, while longer than that needed to determine peaks for these drainage areas, is appropriate for determining runoff volumes. Therefore, a single storm duration and associated synthetic rainfall distribution can be used to represent not only the peak discharges but also the runoff volumes for a range of drainage area sizes.

1.0

111

Fraction of 24-hour rainfall

0.5 1A
1 11

0.0

0

3

6

9 12 15 18 21 24

Time hours

Figure B-1. -SCS 24-Hour Rainfall Distributions

The intensity of rainfall varies considerably during a storm as well as over geographic regions. To represent various regions of the United States, SCS developed four synthetic 24-hour rainfall distributions (I, IA, II, and III) from available National Weather Service (NWS) duration-frequency data (Hershfield 1961; Frederick et al, 1977) or local storm data. Type IA is the least intense and type II the most intense short duration rainfall. The four distributions are shown in figure B-1, and figure B2 shows their approximate geographic boundaries.

Types I and IA represent the Pacific maritime climate with wet winters and dry summers. Type III represents Gulf of Mexico and Atlantic coastal areas where tropical storms bring large 24-hour rainfall amounts. Type II represents the rest of the country. For more precise distribution boundaries in a state having more than one type, contact the SCS State Conservation Engineer.

GaSWCC

(210-VI-TR-55, Second Ed., June 1986)

B-1 A-1-103

Rainfall Distribution
Type I Type IA Type II Type III

Figure B-2. - Approximate Geographic Boundaries for SCS Rainfall Distributions

B-2 A-1-104

(210-VI-TR-55, Second Ed., June 1986)

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Rainfall data sources
This section lists the most current 24-hour rainfall data published by the National Weather Service (NWS) for various parts of the country. Because NWS Technical Paper 40 (TP-40) is out of print, the 24-hour rainfall maps for areas east of the 105th meridian are included here as figures B-3 through B-8. For the area generally west of the 105th meridian, TP-40 has been superseded by NOAA Atlas 2, the Precipitation-Frequency Atlas of the Western United States, published by the National Oceanic and Atmospheric Administration.
East of 105th meridian
Hershfield, D. M. 1961. Rainfall frequency atlas of the United States for durations from 30 minutes to 24 hours and return periods from 1 to 100 years. U.S. Dep. Commerce, Weather Bur. Tech. Pap. No. 40. Washington, DC. 115 p.
West of 105th meridian
Miller, J.F., R.H. Frederick, and R.J. Tracey. 1973. Precipitation-frequency atlas of the Western United States. Vol. I, Montana; Vol. II, Wyoming; Vol. III, Colorado; Vol. IV, New Mexico; Vol. V, Idaho; Vol. VI, Utah; Vol. VII, Nevada; Vol. VIII, Arizona; Vol. IX, Washington; Vol. X, Oregon; Vol. XI, California. U.S. Dep. Commerce, National Weather Service, NOAA Atlas 2. Silver Spring, MD.
Alaska
Miller, John F. 1963. Probable maximum precipitation and rainfall-frequency data for Alaska for areas to 400 square miles, durations to 24 hours and return periods from 1 to 100 years. U.S. Dep. Commerce, Weather Bur. Tech. Pap. No. 47. Washington, DC. 69 p.
Hawaii
Weather Bureau. 1962. Rainfall-frequency atlas of the Hawaiian Islands for areas to 200 square miles, durations to 24 hours and return periods from 1 to 100 years. U.S. Dep. Commerce, Weather Bur. Tech. Pap. No. 43. Washington, DC. 60 p.
Puerto Rico and Virgin Islands
Weather Bureau. 1961. Generalized estimates of probable maximum precipitation and rainfall-frequency data for Puerto Rico and Virgin Islands for areas to 400 square miles, durations to 24 hours, and return periods from 1 to 100 years. U.S. Dep. Commerce, Weather Bur. Tech. Pap. No. 42. Washington, DC. 94 p.

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(210-VI-TR-55, Second Ed., June 1986)

B-3 A-1-105

B-4 A-1-106

A T L A N T I C

N
A
E C O

Figure B-3. - Two-Year, 24-Hour Rainfall (210-VI-TR-55, Second Ed., June 1986)

125

120

115

110

105

100

95

90

85

80

75

70

65

2-YEAR 24-HOUR RAINFALL (INCHES)

P

C

I

F

I

C

A

2
45
40
USE NOAA ATLAS 2 MAPS FOR 11 WESTERN STATES 2
2.5
35

LAK E MICHIG AN

2
L A K E I N T E R I OR

2.5

L A K
2

RON U H E

LA KE

ONTAR I O

E K A L

IE R E

45
2.5

3

3

3.5

40

3.5

O C E A N

4

3.5

3.5

4

4.5

35

5

5

4

5

3.5

4

30
25 115

2 1.5

2 2.5

3 3.5

4 4.5

4.5

5

5.5

6 5.5

5.5

6

5

GULF

OF

MEX ICO

0

100 200 300 400 MI

ALBERS EQUAL AREA PROJECTION STANDARD PARALLELS 25 AND 45

5

4.5

5.5

4.5

6

5

6

5.5

5

110

105

100

95

90

85

80

30
25
4-R-39495-1
75

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Figure B-4. - Five-Year, 24-Hour Rainfall (210-VI-TR-55, Second Ed., June 1986)

125

120

115

110

105

100

95

90

85

80

75

70

65

5-YEAR 24-HOUR RAINFALL (INCHES)
3

P

C

I

F

I

C

A

2.5
45
2.5
40
USE NOAA ATLAS 2 MAPS FOR 11 WESTERN STATES
3
35

2.5 3 L A K E I N T E R I OR
3.5
4 3.5
4.5 5

LAK E MICHIG AN

L A K
2.5

RON U H E

LA KE

ONTAR I O

E K A L

IE R E

45
3.5 4

4

5

4.5

40

4.5

O C E A N

4.5 5
5
5.5 35 6

5 6

4.5

A T L A N T I C

N
A
E C O

30
25 115

2.5 3

5.5

6

6.5

2.5

4

3

4.5

3.5

5

5.5 6 6.5

6.5 7
7.5
8.5

7 8 7.5

7.5 7
GULF

8 8.5
OF

MEX ICO

0

100 200 300 400 MI

ALBERS EQUAL AREA PROJECTION STANDARD PARALLELS 25 AND 45

6

7

7

7.5

76 6.5
6.5

8
8 7.5 7

110

105

100

95

90

85

80

30
25
4-R-39495-2
75

B-5 A-1-107

B-6 A-1-108

125

120

115

110

105

100

95

90

85

80

75

70

65

10-YEAR 24-HOUR RAINFALL (INCHES)

3.5 3

P

45

45

A

3.5 3 L A K E I N T E R I O R

4

C

5
L A K

RON U H E

I

4

LA KE

ONTAR I O

40

F

3
IE R

6

5

40

E

E

K

A

L

O C E A N

LAK E MICHIG AN

I

Figure B-5. - Ten-Year, 24-Hour Rainfall (210-VI-TR-55, Second Ed., June 1986)

C

USE

NOAA

ATLAS

2

MAPS

FOR

11

WESTERN

3
STATES

3.5

35

6 6
35
7

A T L A N T I C

N
A
E C O

30
25 115

6 7
5 4
6

3

3
3.5 4

5 6

7

7

8

9

9

10

9

10

8

GULF

OF

MEX ICO

0

100 200 300 400 MI

ALBERS EQUAL AREA PROJECTION STANDARD PARALLELS 25 AND 45

8 7
9 87
9 8

110

105

100

95

90

85

80

30
25
4-R-39495-3
75

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Figure B-6. - Twenty-Five-Year, 24-Hour Rainfall (210-VI-TR-55, Second Ed., June 1986)

125

120

115

110

105

100

95

90

85

80

75

70

65

25-YEAR 24-HOUR RAINFALL (INCHES)

P

3.5
45

A

C

I

F

40

I

C

USE

NOAA

ATLAS

2

MAPS

FOR

11

WESTERN

3.5
STATES

4

35

3.5

4

LA KE

I N T E R I OR

L A K

4
45
5 6

LAK E MICHIG AN

RON U H E

3.5

LA KE

ONTAR I O

6

IE R

6.5

40

E

E

K

A

L

6 5

O C E A N

6 7

7
35

8

6

7

98

5

8.5

A T L A N T I C

N
A
E C O

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25 115

7

4

3.5
4 5

6 7

8 9

8

9

9

8

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10

11

7

11

10

10

12

10

GULF

OF

MEX ICO

0

100 200 300 400 MI

10

11

98

11

ALBERS EQUAL AREA PROJECTION STANDARD PARALLELS 25 AND 45

9 10

110

105

100

95

90

85

80

30
25
4-R-39495-4
75

B-7 A-1-109

B-8 A-1-110

Figure B-7. - Fifty-Year, 24-Hour Rainfall (210-VI-TR-55, Second Ed., June 1986)

125

120

115

110

105

100

95

90

85

80

75

70

65

50-YEAR 24-HOUR RAINFALL (INCHES)

4.5

P

45

4

5

45

A

4.5L A K E I N T E R I O R

C

RON U H E

6
L A K

5

LA KE

ONTAR I O

6

I

F

4

7

40

IE R

40

E

E

K

A

L

O C E A N

LAK E MICHIG AN

I

C

USE

NOAA

ATLAS

2

MAPS

FOR

11

WESTERN

4
STATES

4.5

35
5

7

6

7 8

8
35
9

98

10

10

A T L A N T I C

N
A
E C O

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25 115

4 3.5
4
4.5 5

67 8

9

8

9

10

10

11

12

13

11

12

9

12

13

11

11 10

GULF

OF

MEX ICO

0

100 200 300 400 MI

ALBERS EQUAL AREA PROJECTION STANDARD PARALLELS 25 AND 45

11

12

10

10

10 12

11

110

105

100

95

90

85

80

30
25
4-R-39495-5
75

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A T L A N T I C

N
A
E C O

Figure B-8. - One-Hundred-Year, 24-Hour Rainfall (210-VI-TR-55, Second Ed., June 1986)

125

120

115

110

105

100

95

90

85

80

75

70

65

100-YEAR 24-HOUR RAINFALL (INCHES)

P

4

5

45

45

A

L A K E I N T E R I OR
5

6 7

C

RON U H E

I

L A K

4

LA KE

ONTAR I O

7

F

6

8

40

IE R

40

E

E K A

L

O C E A N

LAK E MICHIG AN

I

C

USE NOAA ATLAS 2 MAPS FOR 11 WESTERN STATES

5

35

8

8

9

9

7

10

35

11

8 9

7

11

10

8

30
25 115

5 4

5 6

7 8 9

10 11

13 12

9

10 11

12

13

15

13 14

14 15

GULF

OF

MEX ICO

0

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11

10

13

10

14

12

11

14

11

12 13

110

105

100

95

90

85

80

30
25
4-R-39495-6
75

B-9 A-1-111

A-1-112

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Appendix C: Computer program
The TR-55 procedures have been incorporated in a computer program. The program, written in BASIC, requires less than 256K memory to operate and was developed for an MS-DOS operating system. Users of the program, however, still need to be familiar with the procedures in this TR. Features of the program include the following:
The full screen (24 lines, 80 columns) is used to enter data. Flexibility of coding allows movement about the screen for quick data modifications.
Function keys provide menu power to move to different modules (TR-55 chapters) within the program. Some keys are permanently defined while others vary by module.
"Help" screens provide pertinent information to the user depending on location in the program. Two types of information are included: (1) define system operation and (2) describe input parameters.
User files provide for optional entry of local data, such as rainfall-frequency, graphic peak discharge equation coefficients, and tabular hydrographs for other rainfall distributions.
Copies of the program can be obtained from-
National Technical Information Service U.S. Department of Commerce 5285 Port Royal Road Springfield, VA 22161 Telephone (703) 487-4650

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(210-VI-TR-55, Second Ed., June 1986)

C-1 A-1-113

A-1-114

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Appendix D: Worksheets

This appendix contains seven worksheets that can be reproduced for use with chapters 2 through 6. There is no worksheet for chapter 1.

Chapter

Worksheet

2

2

3

3

4

4

5

5a, 5b

6

6a, 6b

GaSWCC

(210-VI-TR-55, Second Ed., June 1986)

D-1 A-1-115

Worksheet 2: Runoff curve number and runoff

Project Location Circle one:

Present Developed

By Checked

Date Date

1. Runoff curve number (CN)

Soil name and
hydrologic group
(appendix A)

Cover description
(cover type, treatment, and hydrologic condition; percent impervious;
unconnected/connected impervious area ratio)

CN 1/

Area
acres mi2 %

Product of
CN x area

Table 2-2 Fig. 2-3 Fig. 2-4

1/ Use only on CN source per line.

CN (weighted)

=

total product total area

=

=

2. Runoff

Totals = ; Use CN =

Storm #1

Storm #2

Storm #3

Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . yr
Rainfall, P (24-hour) . . . . . . . . . . . . . . . . . . . . . . . in
Runoff, Q . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . in (Use P and CN with table 2-1, fig. 2-1, or eqs. 2-3 and 2-4.)

D-2 A-1-116

(210-VI-TR-55, Second Ed., June 1986)

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Worksheet 3: TIme of concentration (Tc) or travel time (Tt)

Project

By

Date

Location

Checked

Date

Circle one: Circle one:

Present Developed Tc Tt through subarea

Notes: Space for as many as two segments per flow type can be used for each worksheet.

Include a map, schematic, or description of flow segments.

Sheet flow (Applicable to Tc only)

Segment ID

1. Surface description (table 3-1) . . . . . . . . . . . . . . . . .

2. Manning's roughness coeff., n (table 3-1) . . . . . . . . .

3. Flow length, L (total L < 300 ft) . . . . . . . . . . . . . . . . ft

4. Two-yr 24-hr rainfall, P2 . . . . . . . . . . . . . . . . . . . . . . in

5. Land slope, s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft/ft

6.

Tt =

0.007 (nL) 0.8 P2 0.5 s 0.4

Compute Tt . . . . . . . hr

Shallow concentrated flow

Segment ID

7. Surface description (paved or unpaved) . . . . . . . . . .

8. Flow length, L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft

9. Watercourse slope, s . . . . . . . . . . . . . . . . . . . . . . . . ft/ft

10. Average velocity, V (figure 3-1) . . . . . . . . . . . . . . . . . ft/s

11.

Tt

=

L 3600 V

Compute Tt . . . . . . . hr

+

=

+

=

Channel flow

Segment ID

12. Cross sectional flow area, a . . . . . . . . . . . . . . . . . . . ft2

13. Wetted perimeter, pw . . . . . . . . . . . . . . . . . . . . . . . . . ft

a

14. Hydraulic radius, r = pw Compute r . . . . . . . .

ft

15. Channel slope, s . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft/ft

16. Manning's roughness coeff., n . . . . . . . . . . . . . . . . . .

17.

V=

1.49 r2/3 s1/2 n

Compute V . . . . . . . . ft/s

18. Flow length, L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft

19.

Tt

=

L 3600 V

Compute Tt . . . . . . . . hr

+

=

20. Watershed or subarea Tc or Tt (add Tt in steps 6, 11, and 19) . . . . . . . . . . . . . . . . . hr

GaSWCC

(210-VI-TR-55, Second Ed., June 1986)

D-3 A-1-117

Project Location: Circle one:

Worksheet 4: Graphical Peak Discharge method

Present Developed

By Checked

Date Date

1. Data:

Drainage area . . . . . . . . . . . . . . . . Am = Runoff curve number . . . . . . . . . . . CN =

Time of concentration . . . . . . . . . . . Tc =

Rainfall distribution type

=

Pond and swamp areas spread throughout watershed . . . . . . . . . . . . . =

mi2 (acres/640) (From worksheet 2) (From worksheet 3) (I, IA, II, III)
percent of Am (

acres or mi2 covered)

2. Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. Rainfall, P (24-hour) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Storm #1

Storm #2

yr

in

Storm #3

4. Initial abstraction, Ia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

in

(Use CN with table 4-1.)

5. Compute Ia/P . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6. Unit peak discharge, qu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (Use Tc and Ia/P with exhibit 4- )

csm/in

7. Runoff, Q . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

in

(From worksheet 2).

8. Pond and swamp adjustment factor, Fp . . . . . . . . . . . . . . . . (Use percent pond and swamp area with table 4-2. Factor is 1.0 for zero percent pond and swamp area.)

9. Peak duscharge, qp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

cfs

(Where qp = quAm QFp )

D-4 A-1-118

(210-VI-TR-55, Second Ed., June 1986)

GaSWCC

GaSWCC

Project Circle one:

Present Developed

Worksheet 5a: Basic watershed data

Location

Frequency (yr)

By Checked

Date Date

Subarea name

Drainage area

Time of concentration

Am

Tc

(mi2)

(hr)

Travel time through subarea
Tt
(hr)

Downstream subarea names

Travel time summation to outlet
Tt
(hr)

24-hr rainfall
P (in)

Runoff curve number

Runoff

CN

Q

(in)

AmQ (mi2-in)

Initial abstrac-
tion

Ia

Ia/P

(in)

(210-VI-TR-55, Second Ed., June 1986)

From worksheet 3

From worksheet 2

From table 5-1

D-5 A-1-119

D-6 A-1-120

Worksheet 5b: Tabular hydrograph discharge summary

Project Circle one:

Present Developed

Subarea name

Basic watershed data used 1/

Sub-

Tt

Ia/P

AmQ

area

to

Tc

outlet

(hr)

(hr)

(mi2-in)

Location

Frequency (yr)

By Checked

Date Date

Select and enter hydrograph times in hours from exhibit 5-

2/

Discharges at selected hydrograph times 3/ (cfs)

(210-VI-TR-55, Second Ed., June 1986)

Composite hydrograph at outlet
1/ Worksheet 5a. Rounded as needed for use with exhibit 5. 2/ Enter rainfall distribution type used. 3/ Hydrograph discharge for selected times is AmQ multiplied by tabular discharge from appropriate exhibit 5.

GaSWCC

Worksheet 6a: Detention basin storage, peak outflow discharge (qo) known

Project Location Circle one:

Present Developed

By Checked

Date Date

Elevation or stage

Detention basin storage

1. Data:

Drainage area . . . . . . . . . Am =

Rainfall distribution

Type (I, IA, II, III)

=

mi2

6. Vs . . . . . . . . . . . . . . . .

Vr (Use

qo qi

with figure 6-1)

1st

2nd

stage stage

2. Frequency . . . . . . . yr
3. Peak inflow discharge, qi . . . . . . . cfs (From worksheet 4 or 5b) 1/
4. Peak outflow discharge, qo . . . . . . cfs
5. Compute qo . . . . . . . . qi

7. Runoff, Q . . . . . . . . in (From worksheet 2)

8. Runoff volume,
Vr . . . . . . . . . . ac-ft (Vr = QAm 53.33)

9. Storage volume,

Vs . . . . . . . . . . ac-ft

(Vs

=

Vr

(

Vs Vr

))

10. Maximum stage, Emax (From plot)

1/ 2nd stage qo includes 1st stage qo.

GaSWCC

(210-VI-TR-55, Second Ed., June 1986)

D-7 A-1-121

Project Location Circle one:

Worksheet 6b: Detention basin peak outflow, storage volume (Vs) known

Present Developed

By Checked

Date Date

Elevation or stage

Detention basin storage

1. Data:

Drainage area . . . . . . . . . . Am =

mi2

Rainfall distribution

Type (I, IA, II, III)

=

1st

2nd

stage stage

6.

Compute

Vs Vr

. . . . . . . .

7.

qo qi

.

(Use

. . . . . . .

Vs Vr

and

. . . . . figure

in 6-1)

2. Frequency . . . . . . . . yr
3. Storage volume, Vs . . . . . . . . . . . ac ft
4. Runoff, Q . . . . . . . . . in (From worksheet 2)
5. Runoff volume, Vr . . . . . . . . . . . ac-ft (Vr = QAm 53.33)

8. Peak inflow discharge, qi . . . . . . cfs (From worksheet 4 or 5b)
9. Peak outflow discharge, qo . . . . . . cfs qo (qo = qi ( qi ) )
10. Maximum stage, Emax (From plot)

1/ 2nd stage qo includes 1st stage qo.

D-8 A-1-122

(210-VI-TR-55, Second Ed., June 1986)

1/
GaSWCC

Appendix E: References
Brakensiek, D.L. and W.J. Rawls. 1983. Green-Ampt infiltration model parameters for hydrologic classification of soils. In John Borrelli, Victor R. Hasfurther, and Robert D. Burman (ed.) Advances in Irrigation and Drainage Surviving External Pressures. Proceedings of Am. Soc. Civ. Eng. specialty conference. New York, NY. p. 226-233.
Chow, V.T. 1959. Open channel hydraulics. McGrawHill Book Company, Inc. New York, NY. p. 109-113.
Comer, G.H., F.D. Theurer, and H.H Richardson. 1981. The Modified Attenuation-Kinematic (Att-Kin) routing model. In V.P. Singh (ed.) Rainfall-Runoff Relationships: Proceedings, International Symposium on Rainfall-Runoff Modeling. Mississippi State University, p. 553-564.
Engman, E.T. 1986. Roughness coefficients for routing surface runoff. Journal of Irrigation and Drainage Engineering 112 (1): 39-53.
Frederick, R.H., V.A. Myers, and E.P. Auciello. 1977. Five to 60 minute precipitation frequency for the Eastern and Central United States. U.S. Dep. Commerce, National Weather Service, National Oceanic and Atmospheric Administration Tech. Memo NWS HYDRO 35. Silver Spring, MD. 36 p.
Hershfield, D.M. 1961. Rainfall frequency atlas of the United States for durations from 30 minutes to 24 hours and return periods from 1 to 100 years. U.S. Dep. Commerce, Weather Bur. Tech. Pap. No. 40. Washington, DC. 115 p.
Linsley, R.K., M.A. Kohler, and J.L.H. Paulhus. 1982. Hydrology for engineers. Third Edition. McGraw-Hill Book Company, Inc. New York, NY. p. 484.
Musgrave, G.W. 1955. How much of the rain enters the soil? In Water. The Yearbook of Agriculture 1955. U.S. Dep. Agric. U.S. Gov. Print. Off. Washington, DC. p. 151-159.
Overton, D.E. and M.E. Meadows. 1976. Storm water modeling. Academic Press. New York, NY. p. 58-88.
Rallison, R.E. and N. Miller. 1981. Past, present, and future SCS runoff procedure. In V.P. Singh (ed.) Rainfall-Runoff Relationships: Proceedings, International Symposium on Rainfall-Runoff Modeling. Mississippi State University, p. 353-364.

Rawls, W.J., A. Shalaby, and R.H. McCuen. 1981. Evaluation of methods for determining urban runoff curve numbers. Transactions of the American Society of Agricultural Engineers 24 (6):1562-1566.
Soil Conservation Service. 1982 [Draft]. Structure site analysis computer program DAMS2 (interim version). SCS Technical Release 48. Washington, DC.
_. 1983 [Draft]. Computer program for project formulation-hydrology. SCS Technical Release 20. Washington, DC.
_. 1985. National engineering handbook. Section 4Hydrology. Washington, DC.

GaSWCC

(210-VI-TR-55, Second Ed., June 1986)

E-1 A-1-123

A-1-124

GaSWCC

Appendix F: Equations for figures and exhibits

This appendix presents the equations used in procedure applications to generate figures and exhibits in TR-55.
Figure 2-1 (runoff equation):

[ ( )] P - 0.2 1000- 10 2

Q =

CN

( ) P + 0.8 1000- 10

CN

where

Q = runoff (in), P = rainfall (in), and CN = runoff curve number.

Figure 2-3 (composite CN with connected impervious area):

CNC = CNp + (Pimp/100)(98 - CNp)
where CN = composite runoff curve number,
c
CNp = pervious runoff curve number, and Pimp = percent imperviousness.
Figure 2-4 (composite CN with unconnected impervious areas and total impervious area less than 30%):

CN = CN + (P /100)(98 - CN )(1 - 0.5R)

C

p

imp

P

where R = ratio of unconnected impervious area to total impervious area.

Figure 3-1 (average velocities for estimating travel time for shallow concentrated flow):

Unpaved Paved

V = 16.1345 (s)0.5 V = 20.3282 (s)0.5

where

V = average velocity (ft/s), and s = slope of hydraulic grade line (watercourse
slope, ft/ft).

These two equations are based on the solution of Manning's equation (Eq. 34) with different assumptions for n (Manning's roughness coefficient) and r (hydraulic radius, ft). For unpaved areas, n is 0.05 and r is 0.4; for paved areas, n is 0.025 and r is 0.2.

Exhibit 4 (unit peak discharges for SCS type I, IA, II, and III distributions):

log(qu) = C0 + C1 log(Tc) + C2 [log(Tc)]2
where q = unit peak discharge (csm/in),
u
Tc = time of concentration (hr) (minimum, 0.1; maximum, 10.0),
and C0, C1, C2 = coefficients from table F-1.
Figure 6-1 (approximate detention basin routing through single- and multiple-stage structures for 24hour rainfalls of the indicated type):

Vs/Vr = C0 + C1 (qo/qi) + C2 (qo/qi)2 + C3 (qo/qi)3

where

V /V = ratio of storage volume (V ) to runoff

sr

s

volume (Vr),

qo/qi = ratio of peak outflow discharge (qo)

to peak inflow discharge (q ), and

i

C0, C1, C2, C3 = coefficients from table F-2.

GaSWCC

(210-VI-TR-55, Second Ed., June 1986)

F-1 A-1-125

Table F-1 - Coefficients for the Equation Used to Generate Exhibits 4-I through 4-III

Rainfall type
I
IA II
III

Ia/P

C0

C1

C2

0.10 2.30550 -0.51429 -0.11750 0.20 2.23537 -0.50387 -0.08929 0.25 2.18219 -0.48488 -0.06589 0.30 2.10624 -0.45695 -0.02835 0.35 2.00303 -0.40769 0.01983 0.40 1.87733 -0.32274 0.05754 0.45 1.76312 -0.15644 0.00453 0.50 1.67889 -0.06930 0.0

0.10 2.03250 -0.31583 -0.13748 0.20 1.91978 -0.28215 -0.07020 0.25 1.83842 -0.25543 -0.02597 0.30 1.72657 -0.19826 0.02633 0.50 1.63417 -0.09100 0.0

0.10 2.55323 -0.61512 -0.16403 0.30 2.46532 -0.62257 -0.11657 0.35 2.41896 -0.61594 -0.08820 0.40 2.36409 -0.59857 -0.05621 0.45 2.29238 -0.57005 -0.02281 0.50 2.20282 -0.51599 -0.01259

0.10 2.47317 -0.51848 -0.17083 0.30 2.39628 -0.51202 -0.13245 0.35 2.35477 -0.49735 -0.11985 0.40 2.30726 -0.46541 -0.11094 0.45 2.24876 -0.41314 -0.11508 0.50 2.17772 -0.36803 -0.09525

Table F-2. - Coefficients for the Equation Used to Generate Figure 6-1

Rainfall

distribution C

C

C

C

0

1

2

3

(appendix B)

I, IA

0.660 -1.76 1.96 -0.730

II, III

0.682 -1.43 1.64 -0.804

F-2 A-1-126

(210-VI-TR-55, Second Ed., June 1986)

GaSWCC

APPENDIX A-2
PEAK DISCHARGES
NRCS CHART METHOD
INTRODUCTION
A quick and reliable method of computing peak discharges from drainage areas 1 to 2,000 acres in size is given in Figures A-2.3 through A-2.5, p. A-2-3 through A-2-5. The charts were prepared for the solution of the general relationships and are based on type-ll rainfall distribution.
Type-ll storms occur in regions where the high rates of runoff from small areas are usually generated from summer thunderstorms.
This chapter presents a method of adjusting peak discharges obtained from the charts to reflect the increase in peak discharge due to urbanization. Additional methods for interpolating or adjusting peak discharges for conditions not found on the charts or not represented by the general equations in this chapter are given later in this chapter.

MODIFICATION OF PEAK DISCHARGE DUE TO URBANIZATION

Research in the area of urban hydrology is developing rapidly. Research to date has been sufficient to identify the parameters that are affected by urbanization and to derive limited empirical relationships between those parameters for both agriculture and urban watersheds. The time to peak for urban watersheds is affected by a decrease in lag or time of concentration as described in TR-55 (Appendix A-1).

Figures A-2.1 and A-2.2 give factors for adjusting peaks calculated from Figures A-2.3 to A-2.5 based on the same parameters that affect watershed lag and time of concentration. The factors are applied to the peak using future-condition runoff curve numbers as follows:

QMOD = Q [Factor imp] [Factor hlm] where

(Eq. A-2.1)

QMOD = modified discharge due to urbanization
Q= Discharge for future CN using charts (Figures A-2.3, A-2.4 or A-2.5)

FactorIMP = adjustment factor for percent impervious areas

FactorHLM = adjustment factor for percent of hydraulic length modified.

PERCENT OF IMPERVIOUS AREA
FUTURE CONTITION C N 95

100

75

90 CN

85 CN CN 80

CN 70

50

25

0

1.0

1.2

1.4

1.6

1.8

PEAK FACTOR

Figure A-2.1 - Factors for Adjusting Peak Discharges for a Given Future-Condition Runoff Curve Number Based on the Percentage of Impervious Area in the Watershed

GaSWCC

A-2-1

PERCENT OF HYDRAULIC LENGTH MODIFIED FUTURE CONTITION C N 95

100

90 CN

CN 85

CN 80

75

CN 70

50

25

0

1.0

1.2

1.4

1.6

1.8

PEAK FACTOR

Figure A-2.2 - Factors for Adjusting Peak Discharges for a Given Future-Condition Runoff Curve Number Based on the Percentage of Hydraulic Length Modified.

Example A-2.1

6. Future-condition peak discharge is:

A 300-acre watershed is to be developed. The runoff curve number for the proposed development is computed to be 80. Approximately 60 percent of the hydraulic length will be modified by the installation of street gutters and storm drains to the watershed outlet. Approximately 30 percent of the watershed will be impervious. The average watershed slope is estimated to be 4 percent. Compute the present-condition and anticipated future-condition peak discharge for a 50-year/24-hour storm event with 5 inches of rainfall. The present-condition runoff curve number is 75.
1. From TR-55, Table 2-1 (Appendix A-1), the runoff for present condition is 2.45 inches and for future conditions is 2.89 inches.
2. From the chart for moderate slope in Figure A2.4 (CN = 75), the present condition peak discharge is 120 cfs (cubic feet per second) per inch of runoff. The peak discharge is then 120 x 2.45 or 294 cfs.
3. From the chart for moderate slope in Figure A2.4 (CN = 80), the future-condition base discharge for (CN = 80) is 133 cfs per inch of runoff. The base discharge is then 133 x 2.89 or 384 cfs.
4. From Figure A-2.1 with 30 percent impervious area and future runoff curve number of 80, read peak factor = 1.16.
5. From Figure A-2.2, with 60 percent of the hydraulic length modified and future-condition curve number of 80, read peak factor = 1.42.

384 (1.16)(1.42) = 633 cfs
7. The effect of this proposal development is to increase the peak discharge from 294 to 633 cfs.
ADJUSTMENT FACTORS FOR PEAKS DETERMINED USING FIGURES A-2.3 THROUGH A-2.5
This section describes methods for adjusting peak rates of discharge for ranges of flat, moderate, and steep slopes; for conditions where swamps or ponding areas exist; and for conditions where the watershed shape factor (l/w) varies significantly from that used in the development of the charts of Figures A-2.3 through A-2.5.
SLOPE INTERPOLATION
Table A-2.1 provides interpolation factors to be used in determining peak rates of discharge for specific slopes within ranges of flat, moderate, and steep slopes for a range of drainage areas. Figure A-2.3, for FLAT slopes is based on 1-percent slope, Figure A-2.4, for MODERATE slopes on 4-percent slope, and Figure A-2.5 for STEEP slopes on 16-percent slope. For slopes other than 1, 4, and 16 percent, use the factors shown in Table A-2.1 to modify the peak discharges.
Example A-2.2
Compute the peak discharge for a 1,000-acre watershed with an average watershed slope of 7 percent and a runoff curve number (CN) of 80 for central Lee County, 2-year/24-hour storm.

A-2-2

GaSWCC

PEAK DISCHARGE, CFS/INCH OF RUNOFF

1000 500
200 100
50
20 10
5

FLAT SLOPES LESS THAN 3%

CN 90 CN 80 CN 70

CN 60

2

1

1

2

5

10

20

50 100 200

500

DRAINAGE AREA, ACRES

2000

PEAK RATES OF DISCHARGE FOR SMALL WATERSHEDS (24 HOUR, TYPE II STORM DISTRIBUTION)

GaSWCC

Figure A-2.3

A-2-3

PEAK DISCHARGE, CFS/INCH OF RUNOFF

1000 500
200 100
50

MODERATE SLOPES 3% TO 8%

CN 90 CN 80 CN 70 CN 60

20 10
5

2

1

1

2

5

10

20

50 100 200

500

DRAINAGE AREA, ACRES

2000

PEAK RATES OF DISCHARGE FOR SMALL WATERSHEDS (24 HOUR, TYPE II STORM DISTRIBUTION)

A-2-4

Figure A-2.4

GaSWCC

1000 500
200 100
50

STEEP SLOPES ABOVE 8%

CN 90

CN 80

CN 70

CN 60

PEAK DISCHARGE, CFS/INCH OF RUNOFF

20 10
5

2

1

1

2

5

10

20

50 100 200

500

DRAINAGE AREA, ACRES

2000

Figure A-2.5. - Peak Rates of Discharge for Small Watersheds (24-Hour, Type II Storm Distribution)

1. Determine the peak discharge for a watershed with a moderate slope (4 percent). From Figure A-2.4, read a peak discharge of 295 cfs per inch of runoff for 1,000 acres and a CN of 80. From Figure A-2.8, Lee County has a P value of 4.0 inches. From TR-55, Table 2-1 (Appendix A-1) find 2.04 inches of runoff from 4 inches of rainfall and a CN of 80. The peak discharge is then 295 x 2.04 or 602 cfs.
2. Determine the interpolation factor. From Table A-2.1, find 7-percent slope under MODERATE heading and read an interpolation factor of 1.23 for a drainage area of 1,000 acres. (The peak from a 1,000-acre watershed with a watershed slope of 7 percent is 1.23 times greater than for an average watershed slope of 4 percent.)
3. Determine the peak discharge of 7-percent slope.
q = (602)(1.23) = 740 cfs
GaSWCC

Examples A-2.3
Compute the peak discharge for a 15-acre watershed with an average slope of 0.5 percent and a runoff curve number of 80 for 4 inches of rainfall.
1. Determine the peak discharge for a watershed with a flat slope (1 percent). From Figure A-2.3 read a peak discharge of 11.2 cfs per inch of runoff for 15 acres and a CN of 80. From Table A-2.1, find 2.04 inches of runoff for 4 inches of rainfall and a CN of 80. The peak discharge is then 11.2 x 2.04 or 23 cfs.
2. Determine the interpolation factor. From Table A-2.1 find 0.5-percent slope under FLAT heading. Read a slope interpolation factor of 0.81 interpolated between the values for 10 acres and 20 acres.
3. Determine the peak discharge for 0.5-percent slope.
q = (23)(.81) = 19 cfs
A-2-5

Table A-2.1 - Slope Adjustment Factors by Drainage Areas

Slope (percent)
0.1 0.2 0.3 0.4 0.5 0.7 1.0 1.5 2.0
3 4 5 6 7
8 9 10 11 12 13 14 15 16 20 25 30 40 50

FLAT SLOPES
10 20 50 100 200 500 1,000 2,000 acres acres acres acres acres acres acres acres
0.49 0.47 0.44 0.43 0.42 0.41 0.41 0.40 .61 .59 .56 .55 .54 .53 .53 .52 .69 .67 .65 .64 .63 .62 .62 .61 .76 .74 .72 .71 .70 .69 .69 .69 .82 .80 .78 .77 .77 .76 .76 .76 .90 .89 .88 .87 .87 .87 .87 .87
1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.13 1.14 1.14 1.15 1.16 1.17 1.17 1.17 1.21 1.24 1.26 1.28 1.29 1.30 1.31 1.31
MODERATE SLOPES
.93 .92 .91 .90 .90 .90 .89 .89 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.04 1.05 1.07 1.08 1.08 1.08 1.09 1.09 1.07 1.10 1.12 1.14 1.15 1.16 1.17 1.17 1.09 1.13 1.18 1.21 1.22 1.23 1.23 1.24
STEEP SLOPES
.92 .88 .84 .81 .80 .78 .78 .77 .94 .90 .86 .84 .83 .82 .81 .81 .96 .92 .88 .87 .86 .85 .84 .84 .96 .94 .91 .90 .89 .88 .87 .87 .97 .95 .93 .92 .91 .90 .90 .90 .97 .97 .95 .94 .94 .93 .93 .92 .98 .98 .97 .96 .96 .96 .95 .95 .99 .99 .99 .98 .98 .98 .98 .98 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.06 1.08 1.12 1.14 1.15 1.16 1.17 1.19 1.09 1.11 1.14 1.17 1.20 1.22 1.23 1.24 1.12 1.16 1.20 1.24 1.29 1.31 1.33 1.35 1.17 1.21 1.25 1.29 1.34 1.37 1.40 1.43

ADJUSTMENT FACTORS FOR SWAMPY AND PONDING AREAS
Peak flows determined from Figure A-2.3 through A2.5 assume that the topography is such that surface flow into ditches, drains, and streams is approximately uniform. On very flat areas and where ponding or swampy areas occur in the watershed, a considerable amount of the surface runoff may be retained in temporary storage. The peak rate of runoff should be reduced to reflect this condition. Tables A-2.2, A-2.3, and A-2.4 provide adjustment factors to determine this reduction based on the ratio of the ponding or swampy area to the total watershed area for a range of storm frequencies.
Table A-2.2 contains adjustment factors to be used when the ponding or swampy areas are located in the path of flow in the vicinity of the design point.

Table A-2.3 contains adjustment factors to be used when a significant amount of the flow from the total watershed passes through ponding or swampy areas and these areas are spread throughout the watershed. Table A-2.4 contains adjustment factors to be used when a significant amount of the flow, passes through ponding or swampy areas located in the upper reaches of the watershed.
These conditions may occur in a proposed or existing urban or suburban area and the adjustment factors from Tables A-2.2, A-2.3, or A-2.4 should be applied after the peaks have been adjusted for the effects of urbanization.

A-2-6

GaSWCC

Table A-2.2. - Peak Flow Adjustment Factors where Ponding and Swampy Areas occur at the Design Point

Ratio of drainage area to ponding and swampy area
500 200 100
50 40 30 20 15 10
5

Percentage of ponding and swampy area
0.2 .5
1.0 2.0 2.5 3.3 5.0 6.7 10.0 20.0

Storm frequency (years)

1

2

5

10 25 50 100

0.91 0.92 0.94 0.95 0.96 0.97 0.98 .85 .86 .87 .88 .90 .92 .93 .79 .80 .81 .83 .85 .87 .89 .73 .74 .75 .76 .79 .82 .86 .68 .69 .70 .72 .75 .78 .82 .63 .64 .65 .67 .71 .75 .78 .58 .59 .61 .63 .67 .71 .75 .56 .57 .58 .60 .64 .67 .71 .52 .53 .54 .56 .60 .63 .68 .47 .48 .49 .51 .55 .59 .64

Table A-2.3. - Peak Flow Adjustment Factors where Ponding and Swampy Areas are Spread Throughout the Watershed or occur in Central Parts of the Watershed

Ratio of drainage area to ponding and swampy area
500 200 100
50 40 30 20 15 10
5 4

Percentage of ponding and swampy area
0.2 .5
1.0 2.0 2.5 3.3 5.0 6.7 10.0 20.0 25.0

Storm frequency (years)

1

2

5

10 25 50 100

0.93 0.94 0.95 0.96 0.97 0.98 0.99 .87 .88 .89 .90 .91 .92 .94 .83 .83 .84 .86 .87 .88 .90 .77 .78 .79 .81 .83 .85 .87 .72 .73 .74 .76 .78 .81 .84 .68 .69 .70 .71 .74 .77 .81 .64 .65 .66 .68 .72 .75 .78 .61 .62 .63 .65 .69 .72 .75 .57 .58 .59 .61 .65 .68 .71 .52 .53 .54 .56 .60 .63 .68 .49 .50 .51 .53 .57 .61 .66

Table A-2.4. - Peak Flow Adjustment Factors where Ponding and Swampy Areas are Located only in Upper Reaches if the Watershed

Ratio of drainage area to ponding and swampy area
500 200 100
50 40 30 20 15 10
5

Percentage of ponding and swampy area
0.2 .5
1.0 2.0 2.5 3.3 5.0 6.7 10.0 20.0

Storm frequency (years)

1

2

5

10 25 50 100

0.95 0.96 0.97 0.98 0.98 0.99 0.99 .92 .93 .94 .94 .95 .96 .97 .89 .90 .91 .92 .93 .94 .95 .86 .87 .88 .88 .90 .91 .93 .84 .85 .85 .86 .88 .89 .91 .81 .82 .83 .84 .86 .88 .89 .79 .80 .81 .82 .84 .86 .88 .77 .78 .79 .80 .82 .84 .86 .76 .77 .77 .78 .80 .82 .84 .73 .74 .75 .76 .78 .80 .82

GaSWCC

A-2-7

Example A-2.4
A 5-acre pond is located at the downstream end of a 100-acre watershed in which a housing development is proposed. The average watershed slope is 4 percent and the present-condition curve number is 75. After the installation of the housing development, 30 percent of the watershed will be impervious and 50 percent of the hydraulic length will be modified. The future-condition curve number is estimated to be 80. For a 100-year storm 24-hour duration in central Glascock County, determine the present-condition and future-condition peak discharges downstream of the pond.
1. Determine the present-condition peak discharge assuming the pond is not in place: From Figure A-2.4, find the peak discharge to be 59 cfs per inch of runoff. From Figure A-2.13, the rainfall for central Glascock County is 8 inches. From TR-55, Table 2.1 (Appendix A-1) find the runoff to be 5.04 inches. The peak discharge is 59 x 5.04 or 297 cfs.
2. Determine the ponding adjustment factor: Since the pond is at the lower end of the watershed, use Table A-2.2. The ratio of the drainage area
20,000

to pond area is 100/5 or 20. For a 100-year frequency event, the adjustment factor is 0.75.
3. Compute the present-condition peak discharge:
Q = 0.75 (297) = 233 cfs
4. Compute the basic future-condition peak discharge: From Figure A-2.4, find the peak discharge to be 65 cfs per inch of runoff. From TR-55, Table 2-1, (Appendix A-1), Find the runoff to be 5.62 inches The peak discharge is then 65 x 5.62 or 365 cfs.
5. Determine the modification factors for proposed urbanization: Taken from Figures A-2.1 and A2.2 for a curve number of 80: impervious factor = 1.16; hydraulic length factor = 1.31; urbanization factor = (1.16) (1.31) = 1.52.
6. Compute the future condition peak discharge:
q = 1.52 (365) = 555 cfs
7. Compute the future-condition peak below the pond: From step 2 the ponding factor is 0.75.
q = 0.75 (555) = 416 cfs

LENGTH OF WATERSHED IN FEET

10,000 5,000 3,000 2,000 1,000

where

= 209a .6
= hydraulic length in feet a = Drainage area in acres

FROM HYDROLOGIC DATA FOR EXPERIMENTAL AGRICULTURAL WATERSHEDS IN THE UNITED STATES
AGRICULTURAL RESEARCH SERVICE, USDA

500 10
A-2-8

20

30

50

100

200

300

500

DRAINAGE AREA IN ACRES

Figure A-2.6 - Hydraulic Length and Drainage Area Relationship

1000

2000

GaSWCC

ADJUSTMENT FOR WATERSHED SHAPE FACTOR
The equation used in computing peak discharges from Figures A-2.3 through A-2.5 was based in part on a relationship between the hydraulic length and the watershed area from Agricultural Research Services's studies on small experimental watersheds. Figure A2.6 shows the best fit line relating length to drainage area. The equation of the line is / = 209a0.6. A watershed shape factor, /w (where w is the average width of the watershed), is then fixed for any given drainage area. For example, for drainage areas of 10, 100, and 1,000 acres, the watershed shape factor is 1.58, 2.51, and 3.98, respectively.
There are watersheds that deviate considerably from these relationships. The peaks can be modified for other shape factors. The procedure is as follows:
1. Determine the hydraulic length of the watershed and compute "equivalent" drainage area using / = 209a0.6 or Figure A-2.6.
2. Determine the "equivalent" peak flow from the charts for the "equivalent" drainage area.
3. Compute the "actual" peak discharge for the watershed by multiplying the equivalent peak discharge by the ratio of actual drainage area to the equivalent drainage area.
The factors for modifying the peak for urbanization can then be applied to the revised peak discharge.
Example A-2.5
From a topographic map the hydraulic length of a 100-acre watershed with moderate slopes and a CN of 75 was measured to be 2,200 feet. Determine the peak discharge for a 6-inch, 24-hour rainfall.
1. Determine the equivalent drainage area for a watershed with a hydraulic length of 2,200 feet. From Figure A-2.6, read 51 acres. (Note that in a 100-acre watershed, the hydraulic length would be 3,300 feet from Figure A-2.6).
2. Determine the "equivalent" peak flow from Figure A-2.4 for a drainage area of 51 acres and a CN of 75. Read 37 cfs per inch of runoff. From TR-55 Table 2-1 (Appendix A-1), find the runoff to be 3.28 or 121 cfs.

3. Compute the actual peak discharge for 100 acres.
The peak discharge for the 100-acre watershed with a hydraulic length of 2,200 feet is 237 cfs (versus 194 cfs for a "normal" 100-acre watershed). Adjustments to this peak discharge for urbanization can be made using factors discussed on page A-2-1.
4. The procedure in steps 1, 2, and 3 can be used to determine peak discharges when the actual hydraulic length is longer than that shown on Figure A-2.6. For example, if the actual length were 4,500 feet instead of 3,300 feet, the equivalent area would be 170 acres, as shown in Figure A-2.6.

GaSWCC

A-2-9

GEORGIA

85

84

83

82

81

3.1

WALKER WHITFIELD
W HITE
HABERSHAM

3.5

4.0 4.5

35 DADE

CATOOSA

3.2

MURRAY FANNIN GILMER

UNION TOWNS RABUN

4.5 4.0

1 YEAR - 24 HOUR RAINFALL

3.5

35

CHATTOOGA

3.3

FLOYD

GORDON BARTOW

PICKENS

LUMPKIN

CHEROKEE DAWSON FORSYTH

STEPHENS

HALL BANKS

FRANK

H ART

K. C JA

M

AD ISO

ELBERT

N

SCALE-STATUTE MILES 0 10 20 30 40 50

PAULDING

POLK 34

COBB

BARROW

CLARK OGLETHORPE

34

TALIFER

MORWGALT. AN

HARAL.

CARROLL

DOUGLAS

FULTON

LB EKA D

ROCK

N IN W G N
EW

OCONEE GREENE

S ILKE W

LIN C O LN

3.1

CLAYT.

c DUFFIE M
WARREN

3.4

T.

BIA

FAYETTE

HEARD

Y R EN H

PUTN.

COLUHMMOND IC

33

COWETA

SPALDING BUTTS

TROUP

MERIWET'R PIKE

LAMAR

JAJSOPNEERS

IN BALDW

CK HANCO

GLASJCE.FFERSON R

BURKE

3.2 3.3

33

ASHINGTON W

MONROE

HARRIS

UPSON TALBOT

MUSCO.

F'D CRAW

BIBB PEACH

JOHNSON TWIGGS WLILAKU'NR.ENS

EMANUEL

JENKINS SCREVEN

3.4 3.5

MARION MACTAOYLOR N H O U STO N

3.5 3.6

32

CHATTA. STEWART

SCHLEY

QUIT'M CLAY

WEB.

SUMTER

TERRELL LEE

DOOLY

BLECKLEY

CRISP

PULASKI WILCOX

E DTOEDLGFAIR

BEN HILL TURNER

TOOMBS TATTNALL LONG

HEELERTREMUOTLNETN. W

CANDLER EVANS

JEFF DAVIS

APPLING

W

BULLOCK BRYAN
LIBERTY

. 'M EFCFH'AGTH'M

3.6 3.7
32
3.8

W ORTH
IRWIN

3.7

RANDOLPH

AYN

31

3.9

3.8

CALHOUN DOUGHERTY

TIFT

COFFEE

EARLY

BAKER

MILLER

LL E H ITC M

SEMINOLE DECATUR GRADY

COLQUITT

BER.

ATKINSON

COOK

THOMAS BROOKS LOWNDES

CLINCH

LANIER

WARE

BACON

E

PIERCE BRANTLEY

McINTOSH G
LY N N
CAMDEN

3.9 4.0

CHARLTON

31

ECHOLS

3.6 3.7 3.8
3.9 4.0

3.6 3.7
3.8 3.9

30 85
A-2-10

84

83

82

Figure A-2.7. - Total Rainfall (P) for 1-Year/24-Hour Storm

30
GaSWCC

GEORGIA

85

84

83

82

81

3.7

W HITE
HABERSHAM

WHITFIELD

35 DADE

CATOOSA

3.8
MURRAY FANNIN
GILMER

4.0
UNION TOWNS

5.0
RABUN

35
2 YEAR - 24 HOUR RAINFALL

5.0

WALKER

CHATTOOGA

3.8

FLOYD

GORDON BARTOW

PICKENS

LUMPKIN

CHEROKEE DAWSON FORSYTH

STEPHENS

HALL BANKS

FRANK

H 4.03.8 ART

K. C JA

M

AD ISO

ELBERT

N

3.7

SCALE-STATUTE MILES 0 10 20 30 40 50

PAULDING

POLK 34

COBB

HARAL.

3.9

CARROLL

DOUGLAS

HEARD

FULTON

CLAYT.

LB EKA D

BARROW

CLARK OGLETHORPE

N IN W

OCONEE

S ILKE

G

W

MORWGALT. AN

N EW T.

GREENE

ROCK

TALIFER

Y R EN H

PUTN.

c DUFFIE M
WARREN

LIN C O LN

3.7

BIA COLUHMMOND
IC

FAYETTE

COWETA

SPALDING BUTTS

TROUP

MERIWET'R PIKE

LAMAR

JAJSOPNEERS

CK HANCO

GLASJCE.FFERSON R

BURKE

33

ASHINGTON W

IN BALDW

MONROE

4.0

HARRIS

UPSON TALBOT

BIBB

JENKINS SCREVEN

3.8 3.9
4.0

EMANUEL

F'D CRAW

MUSCO.

PEACH

JOHNSON TWIGGS WLILAKU'NR.ENS

MARION MACTAOYLOR N H O U STO N

32

CHATTA. STEWART

SCHLEY

QUIT'M CLAY

WEB.

SUMTER

TERRELL LEE

DOOLY

BLECKLEY

CRISP

PULASKI WILCOX

E DTOEDLGFAIR

BEN HILL TURNER

TOOMBS TATTNALL LONG

HEELERTREMUOTLNETN. W

CANDLER EVANS

JEFF DAVIS

APPLING

W

BULLOCK BRYAN
LIBERTY

. 'M EFCFH'AGTH'M

W ORTH
IRWIN

4.5

RANDOLPH

AYN

CALHOUN DOUGHERTY

TIFT

COFFEE

BACON

E

McINTOSH

31

EARLY

BAKER

MILLER

LL E H ITC M

SEMINOLE DECATUR GRADY

COLQUITT

BER.

ATKINSON

COOK

THOMAS BROOKS LOWNDES

CLINCH

WARE

CE PIER
BRANTLEY

G LY N N
CAMDEN

LANIER

CHARLTON

34
33
4.5
32
5.0
31

ECHOLS

4.5

5.0 4.5

30 85
GaSWCC

84

83

82

Figure A-2.8. - Total Rainfall (P) for 2-Year/24-Hour Storm

30
A-2-11

GEORGIA

85

84

83

82

81

WALKER WHITFIELD
W HITE
HABERSHAM

4.6
35 DADE

CATOOSA

4.7

4.64.74.84.9 5.0

MURRAY FANNIN

UNION

GILMER

6.0 7.0

TOWNS RABUN

7.0

6.0

5 YEAR - 24 HOUR RAINFALL

35

5.5 5.0

CHATTOOGA GORDON

LUMPKIN

4.8

FLOYD

PICKENS
BARTOW CHEROKEE DAWSON FORSYTH

STEPHENS

HALL BANKS

FRANK

H ART

5.0 4.9

SCALE-STATUTE MILES 0 10 20 30 40 50

4.9
34

PAULDING

POLK

COBB

HARAL.

CARROLL

DOUGLAS

FULTON

LB EKA D

ROCK

K. C JA

M

AD ISO

ELBERT

N

BARROW

CLARK OGLETHORPE

N IN W

OCONEE

S ILKE

G

W

N EW

GREENE

4.8

4.7

LIN C

4.7 3.7

O

LN

4.8

34

TALIFER

MORWGALT. AN

CLAYT.

c DUFFIE M
WARREN

T.

FAYETTE

HEARD

Y R EN H

COWETA

SPALDING BUTTS

TROUP

MERIWET'R PIKE

LAMAR

PUTN. JAJSOPNEERS

CK HANCO

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COLUHMMOND

IC

GLASJCE.FFERSON R

BURKE

4.9 5.0 3.8

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IN BALDW

MONROE

33

33

HARRIS

UPSON TALBOT

BIBB

JENKINS SCREVEN

EMANUEL

F'D CRAW

MUSCO.

PEACH

JOHNSON TWIGGS WLILAKU'NR.ENS

5.5

MARION MACTAOYLOR N H O U STO N

32

CHATTA. STEWART

SCHLEY

QUIT'M CLAY

WEB.

SUMTER

TERRELL LEE

DOOLY

BLECKLEY

CRISP

PULASKI WILCOX

E DTOEDLGFAIR

BEN HILL TURNER

TOOMBS TATTNALL LONG

HEELERTREMUOTLNETN. W

CANDLER EVANS

JEFF DAVIS

APPLING

W

BULLOCK BRYAN
LIBERTY

. 'M EFCFH'AGTH'M

32

W ORTH
IRWIN

RANDOLPH

AYN

CALHOUN DOUGHERTY

TIFT

COFFEE

BACON

E

McINTOSH

6.0

31

EARLY

BAKER

MILLER

LL E H ITC M

SEMINOLE DECATUR GRADY

COLQUITT

BER.

ATKINSON

COOK

THOMAS BROOKS LOWNDES

CLINCH

WARE

CE PIER
BRANTLEY

G LY N N
CAMDEN

LANIER

CHARLTON

31

6.5

ECHOLS

6.5

6.0

5.5

5.5 6.0
6.5 6.5

30 85
A-2-12

84

83

82

Figure A-2.9. - Total Rainfall (P) for 5-Year/24-Hour Storm

30
GaSWCC

GEORGIA

85

84

83

82

81

WALKER WHITFIELD
5.8

5.2

5.4 5.6

35

DADE

CATOOSA

MURRAY FANNIN

GILMER

6.0

7.0

8.0

UNION TOWNS

8.0 RABUN 7.0

10 YEAR - 24 HOUR RAINFALL

W HITE
HABERSHAM

5.4

CHATTOOGA FLOYD

GORDON BARTOW

PICKENS

LUMPKIN

CHEROKEE DAWSON FORSYTH

6.0

STEPHENS

HALL BANKS

FRANK

H ART

5.8

SCALE-STATUTE MILES 0 10 20 30 40 50

5.6
34

POLK

COBB

PAULDING

HARAL.

5.8

CARROLL

DOUGLAS

FULTON

LB EKA D

ROCK

K. C JA

M

AD ISO

ELBERT

N

BARROW

CLARK OGLETHORPE

N IN W

OCONEE

S ILKE

G

W

N EW

GREENE

5.6
LIN C O LN

5.6

TALIFER

MORWGALT. AN

CLAYT.

c DUFFIE M
WARREN

T.

FAYETTE

6.0

HEARD

Y R EN H

COWETA

SPALDING BUTTS

TROUP

MERIWET'R PIKE

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PUTN. JAJSOPNEERS

33

CK HANCO

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IC

GLASJCE.FFERSON R

BURKE

5.8

IN BALDW

6.0

ASHINGTON W

MONROE

HARRIS

UPSON TALBOT

BIBB

JENKINS SCREVEN

EMANUEL

F'D CRAW

MUSCO.

PEACH

JOHNSON TWIGGS WLILAKU'NR.ENS

MARION MACTAOYLOR N H O U STO N

32

CHATTA. STEWART

SCHLEY

QUIT'M CLAY

WEB.

SUMTER

TERRELL LEE

DOOLY

BLECKLEY

CRISP

PULASKI WILCOX

E DTOEDLGFAIR

BEN HILL TURNER

TOOMBS TATTNALL LONG

HEELERTREMUOTLNETN. W

CANDLER EVANS

JEFF DAVIS

APPLING

W

BULLOCK BRYAN
LIBERTY

. 'M EFCFH'AGTH'M

W ORTH
IRWIN

RANDOLPH

AYN

CALHOUN DOUGHERTY

TIFT

COFFEE

BACON

E

McINTOSH

7.0
31

EARLY

BAKER

MILLER

LL E H ITC M

SEMINOLE DECATUR GRADY

COLQUITT

BER.

ATKINSON

COOK

THOMAS BROOKS LOWNDES

CLINCH

LANIER

WARE

CE PIER
BRANTLEY

G LY N N
CAMDEN

CHARLTON

35
34
33
7.0
32
31

ECHOLS

7.0

7.0

30 85
GaSWCC

84

83

82

Figure A-2.10. - Total Rainfall (P) for 10-Year/24-Hour Storm

30
A-2-13

GEORGIA

85

84

83

82

81

WALKER WHITFIELD
6.6
W HITE
HABERSHAM

6.0
35

DADE

6.2

CATOOSA

6.0 6.2 6.4
MURRAY FANNIN

GILMER

6.8 7.0

8.0

UNION TOWNS RABUN

9.0

9.0 8.0

35
25 YEAR - 24 HOUR RAINFALL

CHATTOOGA

6.4

FLOYD

GORDON BARTOW

PICKENS

LUMPKIN

CHEROKEE DAWSON FORSYTH

7.0

STEPHENS

HALL BANKS

FRANK

H ART

6.8 6.6

K. C JA

M

AD ISO

ELBERT

N

SCALE-STATUTE MILES 0 10 20 30 40 50

34
6.6

PAULDING

POLK

COBB

HARAL.

CARROLL

DOUGLAS

FULTON

EKALB D

ROCK

BARROW

CLARK OGLETHORPE

N IN W

OCONEE

S ILKE

G

W

N EW

GREENE

LIN C O LN

6.6

34

TALIFER

MORWGALT. AN

CLAYT.

c DUFFIE M
WARREN

T.

BIA

FAYETTE

6.8 33 7.0

HEARD

RY EN H

COWETA

SPALDING BUTTS

TROUP

MERIWET'R PIKE

LAMAR

PUTN. JAJSOPNEERS

CK HANCO

COLUHMMOND

IC

GLASJCE.FFERSON R

BURKE

6.8

33

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IN BALDW

MONROE

HARRIS

UPSON TALBOT

BIBB

JENKINS SCREVEN

7.0

EM ANUEL

F'D CRAW

MUSCO.

PEACH

JOHNSON TWIGGS WLILAKU'NR.ENS

MARION MACTAOYLOR N H O U STO N

32

CHATTA. STEWART

SCHLEY

QUIT'M CLAY

WEB.

SUMTER

TERRELL LEE

DOOLY

BLECKLEY

CRISP

PULASKI WILCOX

E DTOEDLGFAIR

BEN HILL TURNER

TOOMBS TATTNALL LONG

HEELERTREMUOTLNETN. W

CANDLER EVANS

JEFF DAVIS

APPLING

W

BULLOCK BRYAN
LIBERTY

. 'M EFCFH'AGTH'M

32

WORTH IRWIN

RANDOLPH

AYN

8.0

CALHOUN DOUGHERTY

TIFT

COFFEE

BACON

E

McINTOSH

31

EARLY

BAKER

MILLER

LL E H ITC M

SEMINOLE DECATUR GRADY

COLQUITT

BER.

ATKINSON

COOK

THOMAS BROOKS LOWNDES

CLINCH

WARE

CE PIER
BRANTLEY

G LY N N
CAMDEN

LANIER

CHARLTON

31

9.0

ECHOLS

8.0 9.0

8.0

30 85
A-2-14

84

83

82

Figure A-2.11. - Total Rainfall (P) for 25-Year/24-Hour Storm

30
GaSWCC

GEORGIA

85

84

83

82

81

WALKER WHITFIELD
W HITE
HABERSHAM

35 DADE

CATOOSA

7.0

8.0 9.0 10.0

MURRAY FANNIN GILMER

50 Y - 24 H R UNION TOWNS RABUN

10.0

EAR

35
OUR AINFALL

9.0

7.0

CHATTOOGA FLOYD

GORDON BARTOW

PICKENS

LUMPKIN

CHEROKEE DAWSON FORSYTH

8.0

7.8 STEPHENS

HALL BANKS

FRANK

H ART

7.767.4.2

SCALE-STATUTE MILES 0 10 20 30 40 50

K. C JA

M AD ISO

ELBERT

7.2 POLK
34

COBB

BARROW

N CLARK OGLETHORPE

34

PAULDING

HARAL.

7.4

CARROLL

DOUGLAS

FULTON

LB EKA D

ROCK

N IN W G N
EW T.

MORWGALT. AN

OCONEE GREENE

S ILKE W

LIN C O LN

7.2 7.4
BIA

TALIFER

CLAYT.

c DUFFIE M
WARREN

FAYETTE

HEARD

Y R EN H

PUTN.

COLUHMMOND IC

7.6

7.6

COWETA

SPALDING BUTTS

TROUP

MERIWET'R PIKE

LAMAR

JAJSOPNEERS

CK HANCO

GLASJCE.FFERSON R

BURKE

7.8

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IN BALDW

MONROE

33

33

7.8 HARRIS

UPSON TALBOT

BIBB

JENKINS SCREVEN

EMANUEL

F'D CRAW

JOHNSON

32

8.0

MUSCO. CHATTA. STEWART

SCHLEY

QUIT'M CLAY

WEB.

SUMTER

TERRELL LEE

MARION MACTAOYLOR N H O U STO N

PEACH

TWIGGS WLILAKU'NR.ENS

DOOLY

BLECKLEY

CRISP

PULASKI WILCOX

E DTOEDLGFAIR

BEN HILL TURNER

HEELERTREMUOTLNETN. W

CANDLER EVANS

JEFF DAVIS

APPLING

W

TOOMBS TATTNALL LONG

BULLOCK BRYAN
LIBERTY

8.0
. 'M EFCFH'AGTH'M

32

W ORTH
IRWIN

RANDOLPH

AYN

CALHOUN DOUGHERTY

TIFT

COFFEE

BACON

E

McINTOSH

9.0

EARLY

BAKER

MILLER

LL E H ITC M

COLQUITT

BER.

ATKINSON

CLINCH

COOK

31

SEMINOLE DECATUR GRADY

THOMAS BROOKS LOWNDES

LANIER

WARE

CE PIER
BRANTLEY

G LY N N
CAMDEN

CHARLTON

10.0

31

ECHOLS

9.0

10.0 9.0

30 85
GaSWCC

84

83

82

Figure A-2.12. - Total Rainfall (P) for 50-Year/24-Hour Storm

30
A-2-15

GEORGIA

85

84

83

82

81

WALKER WHITFIELD
W HITE
HABERSHAM

35 DADE

CATOOSA

7.4 7.6 7.8 8.0 9.0 10.0 11.0

35

MURRAY FANNIN GILMER

100 Y - 24 H R UNION TOWNS RABUN 11.0

EAR

OUR AINFALL

10.0

7.6

CHATTOOGA FLOYD

GORDON BARTOW

PICKENS

LUMPKIN

CHEROKEE DAWSON FORSYTH

9.0

STEPHENS

HALL BANKS

FRANK

H ART

8.0 7.8

SCALE-STATUTE MILES 0 10 20 30 40 50

7.8

K. C JA

M

AD ISO

ELBERT

N

7.6

34
8.0

PAULDING

POLK

COBB

HARAL.

CARROLL

DOUGLAS

FULTON

LB EKA D

ROCK

BARROW

CLARK OGLETHORPE

N IN W

OCONEE

S ILKE

G

W

N EW

GREENE

LIN 7.6 C O LN

7.8

TALIFER

MORWGALT. AN

CLAYT.

c DUFFIE M
WARREN

T.

BIA

FAYETTE

HEARD

Y R EN H

PUTN.

COLUHMMOND IC

8.0

COWETA

SPALDING BUTTS

TROUP

MERIWET'R PIKE

LAMAR

JAJSOPNEERS

CK HANCO

GLASJCE.FFERSON R

BURKE

33

ASHINGTON W

IN BALDW

MONROE

HARRIS

UPSON TALBOT

BIBB

JENKINS SCREVEN

EMANUEL

F'D CRAW

MUSCO.

PEACH

JOHNSON TWIGGS WLILAKU'NR.ENS

9.0

MARION MACTAOYLOR N H O U STO N

32

9.0

CHATTA. STEWART

SCHLEY

QUIT'M CLAY

WEB.

SUMTER

TERRELL LEE

DOOLY

BLECKLEY

CRISP

PULASKI WILCOX

E DTOEDLGFAIR

BEN HILL TURNER

TOOMBS TATTNALL LONG

HEELERTREMUOTLNETN. W

CANDLER EVANS

JEFF DAVIS

APPLING

W

BULLOCK BRYAN
LIBERTY

. 'M EFCFH'AGTH'M

W ORTH
IRWIN

RANDOLPH

AYN

CALHOUN DOUGHERTY

TIFT

COFFEE

BACON

E

McINTOSH

34
33
10.0
32

11.0

10.0

EARLY

BAKER

MILLER

LL E H ITC M

31

11.0

SEMINOLE DECATUR GRADY

COLQUITT

BER.

ATKINSON

COOK

THOMAS BROOKS LOWNDES

CLINCH

LANIER

CE PIER
BRANTLEY

G LY N N
CAMDEN

CHARLTON

31

ECHOLS

11.0

11.0 10.0
WARE
10.0

30 85
A-2-16

84

83

82

Figure A-2.13. - Total Rainfall (P) for 100-Year/24-Hour Storm

30
GaSWCC

APPENDIX A-3

PROCEDURAL GUIDE FOR COMPUTING RUN-OFF BY RATIONAL METHOD

The Rational Method is a method for determining runoff in terms of cubic feet per second at the drainage structure. It is based on the direct relationship between rainfall and run-off and may be expressed by the formula:
Q = CIA
Q = the run-off in cu. ft. per sec. from a given area.

C = a coefficient representing the ratio of run-off to rainfall (related to impervious area) i.e., 1.0-100% run-off.
I = the intensity of rainfall in inches per hour for a duration equal to the time of concentration and for a stated frequency.
A = the drainage area in acres.

Table A-3.1

SLOPE

LAND USE

Flat (0% - 3%)
Rolling (3% - 7%)
Hilly (7% - 11%)
Mountainous (11% +) Steep Grassed Slopes

Woodlands Pasture Paved Residential Commercial
Woodlands Pasture Paved Residential Commercial
Woodlands Pasture Paved Residential Commercial
Woodlands Bare
Pasture

SOIL CLASSIFICATION

SAND OR SANDY

LOAM SOILS

(Pervious)

Min.

Max.

0.15

0.20

0.20

0.25

0.95

0.35

0.60

0.60

0.95

HIGH CLAY SOILS
(Impervious) Min.
0.20 0.25
0.95 0.50 0.60

0.15

0.20

0.18

0.30

0.40

0.35

0.95

0.95

0.50

0.60

0.50

0.60

0.95

0.60

0.20

0.25

0.25

0.35

0.45

0.45

0.95

0.95

0.50

0.60

0.50

0.60

0.95

0.60

0.70

0.80

0.80

Max. 0.25 0.30
0.60 0.95
0.25 0.45
0.60 0.95
0.30 0.55
0.60 0.95
0.80 0.95

0.70

0.70

GaSWCC (Amended - 1995)

A-3-1

1. Determine "C" by observation in the field of culture and soils and by use of Table A-3.1, p. A3-1.
2. Determine "I" (intensity rate) from the time of Concentration Figure A-3.1, p. A-3-3 and Rainfall Figures A-3.3 through A-3.7, p. A-3-5 through A-3-9.
NOTE:
a. Height (ft.) is determined in the field or from contour maps. Height is the difference in elevation of the most remote point in the drainage area and the inlet flow line of the structure.
b. Maximum length of travel is determined in the field or from the contour maps. It is the greatest distance the water will travel from the most remote point of the drainage area to the inlet of the drainage structure.
c. Use height and length to determine the time of concentration by use of Figure A-3.1. Use a minimum of 10 minutes for rural and urban areas.
d. Now refer to rainfall figures - Atlanta, Macon, Augusta, Thomasville and Savannah (use figure nearest to project or combination of two figures) and by scaling the time of concentration, which is equal to the rainfall duration, along the bottom of the table and moving up to the selected return period, (10-25-50 yr.), move horizontally to the left and read the intensity "I".
3. Determine the time of concentration using the "Kinematic Wave Nomograph," Figure A-3.2, p. A-3-4. The kinematic wave table incorporates variables, the rainfall intensity and mannings "n." In using the nomograph, the designer has two unknowns starting the computations, the time of concentration and the rainfall density. The problem is attempting to determine a rainfall intensity which, in turn, actually determines the time of concentration. Thus, the problem is one of iteration. A value of "i" must be assumed, compute a time of concentration and then check back to see if the rainfall intensity that was assumed is consistent with the frequency curve of Figures A-3.3 through A-3.7. If one is the given length, slope, roughness coefficient, and intensity-duration-frequency curve the steps are as follows:

a. Assume rainfall intensity.
b. Use kinematic wave nomograph or equation to obtain first estimate of time concentration.
c. Using the time of concentration obtained from Step "b", enter Figures A-3.3 through A-3.7 for appropriate area and find rainfall intensity corresponding to the computed time of concentration. If this rainfall intensity corresponds with the assumed intensity, the problem is solved. If not, proceed to Step "d".
d. Assume a new rainfall intensity that is between that assumed in Step "a" and that determined in Step "c."
e. Repeat Steps "a" through "c" until there is good agreement between the assumed rainfall intensity and that obtained from Figures A-3.3 through A-3.7. Experience has shown that a solution can be found on the third iteration with little difficulty.
Generally, the time of concentration for overland flow is only a part of the overall design problem. Often one encounters swale flow, confined channel flow, and closed conduit flow-times that must be added as part of the overall time of concentration. When this situation is encountered, it is best to compute the confined flowtimes as the first step in the overall determination of the time of concentration. This will give the designer a rough estimate of the time involved for the overland flow which will give a better first start on the rainfall intensity assumption. For example, if the flow time in a channel is 15 minutes and the overland flow time from this ridge line to the channels is 10 minutes, then the total time of concentration is 25 minutes. The channel flow can be determined by length divided by velocity.
4. Determine drainage Area "A" in the field or from contour maps.
5. Multiply the values of C x I x A to determine Q (cu. ft. per sec).
6. Using "Q" as determined above, solve for size of structure required by use of Culvert Capacity Charts or nomographs.
Table A-3.2, p. A-3-10 may be used for organizing computation.

A-3-2

GaSWCC (Amended - 1995)

HEIGHT OF MOST REMOTE POINT ABOVE OUTLET MAXIMUM LENGTH OF TRAVEL
TIME OF CONCENTRATION

H (FT.) 500 400 300 200 150 100
50 40 30 20
10

EXAMPLE HEIGHT = 100 FT. LENGTH = 3,000 FT. TIME OF CONCENTRATION = 14 MIN.

EXAMPLE

L (FT.) 10,000
5,000
3,000 2,000 1,500 1,000

5

500

4

3

300

USE AS MINIMUM:

2 10 MIN. ON RURAL

200

ON URBAN

150

100 1

TIME OF CONCENTRATION OF SMALL DRAINAGE BASINS

TC (MIN.) 200 150
100 80 60 50 40 30 25 20 15
10 8 6 5 4 3
2
1

Based on study by P. Z. Kirpich, Civil Engineering, Vol. 10, No. 6, June 1940, p. 362

GaSWCC (Amended - 1995)

Figure A-3.1

A-3-3

A-3-4

Length Ft.

Rainfall, In/Hr. Slope, Ft./Ft.

Equation solved by nomograph:
1000 800

tc (Sec) = 56

Lo.6 R.6 i.4 So.3

0.50

0.1.005

600

0.30

500

400

100 0.2

.01 300

40

0.5

First Tuning Line Second Tuning Line Time, Minute

200

0.1

20

0.08

150

1

10 0.06

.02

100

0.05

0.04

2

Manning "n"

50
20 The initially assumed value of i and the nomograph value of t must be checked against the applicable intensity-duration-frequency curve by trial and error.

0.03
0.02 0.015
0.010
Example: Lo= 400ft. n = 0.015 i = 5.5 in/hr So= 0.01 t = 5.5 min.

3 .03
4 5 .04 6
.05 8 10 .06
ONE INCH is 25.4mm ONE FOOT is 0.3048m

Nomograph for determining time of concentration for overland flow, Kinematic Wave Formulation. (After Ragan.)

Figure A-3.2

GaSWCC (Amended - 1995)

ATLANTA, GEORGIA 1903-1951
20.0

15.0
NOTE

FREQUENCY ANALYSIS BY METHOD OF

10.0

EXTREME VALUES, AFTER GUMBEL

8.0

6.0

4.0 2.0

RE1T0U0RN 25 50 10

PERIOD

(YEARS)

5

2
1.0

0.8

0.6

0.4

RAINFALL INTENSITY IN INCHES PER HOUR

0.2

0.1 .08 .06
.04

.02 5

10

15 20

30 40 50 60

2

3 4 5 6 8 10 12

MINUTES

TIME OF CONCENTRATION

HOURS

WEATHER BUREAU TECHNICAL PAPER 25

18 24

Figure A-3.3

GaSWCC (Amended - 1995)

A-3-5

RAINFALL INTENSITY IN INCHES PER HOUR

AUGUSTA, GEORGIA 1903-1951
20.0

15.0
NOTE

FREQUENCY ANALYSIS BY METHOD OF

10.0

EXTREME VALUES, AFTER GUMBEL

8.0

6.0

4.0 2.0

RETU52R05N1P0E0RIOD 10

(YEARS)

5

2

1.0

0.8

0.6

0.4

0.2

0.1 .08 .06
.04

.02 5

10

15 20

30 40 50 60

2

3 4 5 6 8 10 12

MINUTES

TIME OF CONCENTRATION

HOURS

WEATHER BUREAU TECHNICAL PAPER 25

18 24

Figure A-3.4

A-3-6

GaSWCC (Amended - 1995)

MACON, GEORGIA 1903-1951
20.0

15.0
NOTE

FREQUENCY ANALYSIS BY METHOD OF

10.0

EXTREME VALUES, AFTER GUMBEL

8.0

6.0

4.0 2.0

10R0ETURN 25 50 10
5

PERIOD

(YEARS)

2
1.0 0.8

0.6

0.4

RAINFALL INTENSITY IN INCHES PER HOUR

0.2
0.1 .08 .06 .04

.02 5

10

15 20

30 40 50 60

2

3 4 5 6 8 10 12

MINUTES

TIME OF CONCENTRATION

HOURS

WEATHER BUREAU TECHNICAL PAPER 25

18 24

Figure A-3.5

GaSWCC (Amended - 1995)

A-3-7

SAVANNAH, GEORGIA 1903-1951
20.0

15.0
NOTE

FREQUENCY ANALYSIS BY METHOD OF

10.0

EXTREME VALUES, AFTER GUMBEL

8.0

6.0

4.0

RE5T0U1R0N0 PERIOD 10 25
5

(YEARS)

2.0

2

1.0 0.8 0.6
0.4

RAINFALL INTENSITY IN INCHES PER HOUR

0.2

0.1 .08 .06
.04

.02 5

10

15 20

30 40 50 60

2

3 4 5 6 8 10 12

MINUTES

TIME OF CONCENTRATION

HOURS

WEATHER BUREAU TECHNICAL PAPER 25

18 24

Figure A-3.6

A-3-8

GaSWCC (Amended - 1995)

THOMASVILLE, GEORGIA 1906-1923, 1926-1932
20.0

15.0
NOTE

FREQUENCY ANALYSIS BY METHOD OF

10.0

EXTREME VALUES, AFTER GUMBEL

8.0

6.0

4.0

RE5T0U1R0N0 PERIOD 10 25
5

(YEARS)

2.0

2

1.0 0.8 0.6
0.4

RAINFALL INTENSITY IN INCHES PER HOUR

0.2

0.1 .08 .06
.04

.02 5

10

15 20

30 40 50 60

2

3 4 5 6 8 10 12

MINUTES

TIME OF CONCENTRATION

HOURS

WEATHER BUREAU TECHNICAL PAPER 25

18 24

Figure A-3.7

GaSWCC (Amended - 1995)

A-3-9

A-3-10

GaSWCC (Amended - 1995)

DESIGN RETURN PERIOD _______YR. DESCRIPTION

LOCATION

SKEW

Table A-3.2
DRAINAGE DESIGN COMPUTATIONS
DISCHARGE "Q." COMPUTED BY RATIONAL METHOD
HYDROLOGY

DRAINAGE AREA (ACRES)
RUNOFF "C"
LENGTH (FEET)
HEIGHT (FEET)
TIME OF CONC: (MIN)
INTENSITY "I"50 IN/HR
INTENSITY "I"100 IN/HR
DISCHARGE "Q"50 (CFS)
DISCHARGE "Q"100 (CFS)
STRUCTURE SLOPE "So" (FT./FT.) STRUCTURE LENGTH "L" (FT.)
L 100SO
ALLOWABLE HEADWATER "AHW" (FT.)
HEADWATER "HW" 50
HEADWATER "HW" 100
SIZE AND TYPE STRUCTURE

HYDRAULICS

PROJ. NO. _______________ COUNTY _______________

REMARKS

APPENDIX B-1

SOILS INFORMATION

The soils information in Appendix B has been assembled to assist the plan preparer and reviewer in accomplishing responsibilities under Act 599.

Appendix B-1 contains charts of Georgia's soils series with estimated soil properties and soils limitations for urban uses. These charts may be used in conjunction with published soil survey information or other soils maps available through the Soil and Water Conservation Districts and the Natural Resources Conservation Service.

Appendix B-2 contains excerpts from NRCS Technical Release No. 51, "Procedure for Computing Sheet and Rill Erosion on Project Areas." Also included is a method for estimating soil erodibility or "K" values and sediment delivery ratio charts.This Appendix should be of assistance in planning for land-disturbing activities.

Explanation of Charts: Appendix B-1 Soil Series Interpretations

Column 1: Soil Series

This column lists alphabetically the name of all the soil series which are used in the State of Georgia.

Column 2: Permeability

Soil permeability is the quality that enables soil to transmit water and air. Accepted as a measure of this quality is the rate at which soil transmits water while saturated. That rate is the "saturated hydraulic conductivity" of soil physics. In line with conventional usage in the engineering profession and traditional usage in the published soil surveys, this rate of flow, principally downward, continues to be expressed as "permeability". The permeability of a soil is the rate of flow for the most restrictive layer in the profile.

Soil permeability is rated using the numerical ranges shown below:

Permeability class
Very slow Slow Moderately slow Moderate Moderately rapid Rapid Very Rapid

Numerical range (inches per hour) Less than 0.06 0.06 - 0.2 0.2 - 0.6 0.6 - 2.0 2.0 - 6.0 6.0 - 20 More that 20

GaSWCC

Column 3: Soil Reaction
The degree of acidity or alkalinity of a soil is expressed in pH values. A soil with a pH 7.0 is precisely neutral in reaction. The pH ranges given in this column are the high and low values for the soil profile. The surface layer may be higher due to the addition of lime.
Column 4: Shrink-Swell Potential
Shrink-swell behavior is the quality that determines soil's volume change with change in moisture content. Building foundations, roads and other structures may be severely damaged by the shrinking and swelling of the soil. The volume change of soil is influenced by the amount of moisture change and the amount and kind of clay in the soil profile.
The shrink-swell interpretations are relevant to structures, such as houses and other low buildings, streets and roads, and parking lots. Three classes have been developed to express shrink-swell behavior; low, moderate and high.
Column 5 and 6: Corrosivity
Various metals and other materials corrode when on or in the soil, and some metals and materials corrode more rapidly when in contact with specific soils than when in contact with others. To be meaningful, corrosivity must be rated in relation to specific structural material. In these columns the soil series are given ratings on potential for inducing corrosion of uncoated steel (column 5) and of concrete (column 6).
Soils are assigned to one of three classes of corrosivity: low, moderate, or high.
Columns 7 and 8: Depth to Watertable and Bedrock
The depth to the watertable is given in feet (to the nearest half-foot). The value given is an indication of how close to the soil surface the watertable will rise during the wet season.
Depth to bedrock is given in inches. Hardness of rock may range from "rippable", which can be excavated using a single tooth ripping attachment on a 200 - 300 horsepower tractor, to "hard", where excavation may require blasting. Rock hardness should be determined by on-site-investigation.
Both the depth to watertable and bedrock are estimates-actual depths may vary from site to site.
B-1-1

Column 9: Flood Frequency
Flood frequency is an indicator of how often if ever, floods occur. Ratings are as follows:
None: No reasonable possibility of flooding.
Rare: Flooding unlikely but possible under unusual weather conditions.
Occasional: Flooding is expected infrequently under usual weather conditions.
Frequent: Flooding is likely to occur often under usual weather conditions.
Column 10: Hydrologic Soil Group
The hydrologic soil group parameter, A, B, C, or D, is an indication of the minimum rate of infiltration obtained for a bare soil after prolonged wetting.
The hydrologic soil groups range from A, which are deep sands or gravels with low runoff, to D, which are soils with a permanent high water table, soils with a claypan or clay layer at or near the surface, and shallow soils over nearly impervious material.
Some soil series may have a dual hydrologic soil group rating. The dual ratings are given for certain wet soils that can be adequately drained. The criteria used is making dual group ratings are as follows:
1. Soils are rated D in their natural condition.
2. Drainage is feasible and practical.
3. Drainage improves the hydrologic group by at least two classes (from D to A or B).
Columns 11-16: Limitation of Soils For Urban Uses
The soils are rated L for slight limitations, M for moderate limitations, or S for severe limitations.
A slight soil limitation (L) is the rating given soils that have properties favorable for the rated use. The degree of limitation is minor and can be overcome easily. Good performance and low maintenance can be expected.
A moderate soil limitation (M) is the rating given soils that have properties moderately favorable for the rated use. This degree of limitation can be overcome or modified by special planning, design, or maintenance. During some part of the year, the performance of the structure or other planned use is somewhat less desirable than for soils rated slight. Some soils rated moderate
B-1-2

required treatment such as artificial drainage, runoff control to reduce erosion, extended sewage absorption fields, extra excavation, or some modification of certain features through manipulation of the soil. For these soils, modification is needed for those construction plans generally used for soils of slight limitation. Modification may include special foundations, extra reinforcement of structures, sump pumps, etc.
A severe soil limitation (S) is the rating given soils with one or more properties unfavorable for the rated use, such as steep slopes, bedrock near the surface, flooding hazard, high shrink-swell potential, a seasonal high watertable or low bearing strength. This degree of limitation generally requires major soil reclamation, special design, or intensive maintenance. Some of these soils, however, can be improved by reducing or removing the soil feature that limits use. In most situations, however, it is difficult and costly to alter the soil or to design a structure to compensate for a severe degree of limitation.
Following the limitation rating symbol will be a lower case symbol to indicate the reason for the particular rating. These symbols are s-slope, w-wetness, f-flooding, pk-slow percolation, cl-too clayey, ss-shrink swell potential, b-low bearing strength, r-shallow depth to rock, p-seepage, st-stones, cc-cutbanks may cave, h-too much humas, pf-poor filter, d-dense layer.
A number followed by a % indicates percent slope; for example 2-6% reads two to six percent slope.
Some soil series may have a flood frequency listing of two rating (Example: None-Occasional). Such soils may consequently have a two rating limitation. For example, a listing of means, if the soil is located where no flooding occurs, it is rated Moderate due to wetness and, if occasional flooding occurs, it is rated as Severe due to flooding.
None: M; w Occ; S; f
Column 11: Septic Tank Absorption Fields
A septic tank absorption field is a soil absorption system for sewage disposal. It is a subsurface tile system laid in such a way that effluent from the septic tank is distributed with reasonable uniformity into the natural soil. Criteria used for rating soils (slight, moderate, and severe) for use as absorption fields are based on the limitations of the soil to absorb effluent.
Column 12: Sewage Lagoon Areas
A sewage lagoon (aerobic) is a shallow lake used to hold sewage for the time required for bacterial decom-
GaSWCC

position. Sewage lagoons require consideration of the soils for two functions, (1) as a vessel for the impounded area and (2) as soil material for the enclosing embankment. The requirements for this embankment are the same as for other embankments designed to impound water. Enough soil material that is suitable for the structure must be available, and, when the lagoon is properly constructed, it must be capable of holding water with minimum seepage. The material should be free of coarse fragments (over 10 inches in diameter) that interfere with compaction.
Column 13: Shallow Excavations
These excavations require excavating or trenching to a depth of 5 or 6 feet. Note that limitation ratings for shallow excavations alone, though highly relevant, are insufficient for interpretations for ultimate uses, such as for dwellings with basements, sanitary landfills, cemeteries, and underground utility lines (sewers, pipelines, and cables). Additional soil features must be considered in evaluating for those uses. For example, additional interpretation concerning shrink-swell potential and corrosivity are needed for giving ratings for the ultimate use of soils for pipelines.
Column 14: Dwellings
This column gives ratings for undisturbed soils on which single-family dwellings or other structures with similar foundation requirements can be built. Buildings of more than three stories and other buildings requiring a foundation load in excess of that of a three-story dwelling are not considered in the entries in this column.
In some cases, a rating may differ depending on whether the dwelling will or will not have a basement. In such cases, the rating is marked with an asterisk (*) for dwellings with basements and a pound sign (#) for ones without basements.
Column 15: Small Commercial Buildings
This column provides limitations for commercial buildings of 3 stories or less.
Column 16: Local Roads and Streets
The limitation ratings given in this column apply to use of soils for construction and maintenance of improved local roads and streets that have all-weather surfacing-commonly asphalt or concrete-and that are expected to carry automobile traffic all year. The roads and streets consist of (1) underlying local soil material, whether cut or fill, that is called "the subgrade"; (2) the base material of gravel, crushed rock, lime-stabilized soil, or soil-cement-stabilized soils; and (3) the actual
GaSWCC

road surface or street pavement that is either flexible (asphalt), rigid (concrete), or, in some rural areas, gravel with binder in it. These roads and streets also are graded to shed water and conventional drainage measures are provided. With probable exception of the hard surfaces, the roads and streets are built mainly from the soil at hand; cuts and fills generally are limited to less than 6 feet of thickness. Excluded from consideration in the ratings in this column are highways designed for fast moving heavy trucks.
Also, the ratings cannot substitute for basic soil data and for on site investigation.
KEY TO SYMBOLS-SOIL SURVEY INTERPRETATIONS
Limitations of Soils: L - Slight Limitation M - Moderate Limitation S - Severe Limitation
Reasons for Limitations: s - slope w - wetness f - flooding pk - slow percolation cl - too clayey ss - shrink-swell potential b - low bearing strength r - depth to rock P - seepage st - stones cc - cutbank may cave pf - poor filter h - too much humus d - dense layer
Appendix B-2 Soil Loss Predictions
The first portion of Appendix B-2 is the SCS Technical Release No. 51, "Procedure for Computing Sheet and Rill Erosion on Project Areas." It explains the use of the Universal Soil-Loss Equation.
Also included in Appendix B-2 is a guide for developing the Soil Erodibility Factor (K).
Another section is devoted to applying sediment delivery ratio charts to the Universal Soil-Loss Equation for estimating sediment yields.
Additional information includes a textural classification chart and a chart for comparing different soil classification systems.
B-1-3

B-1-4

GaSWCC

SOIL SERIES INTERPRETATIONS

SOIL SERIES AILEY ALAPAHA ALBANY ALBERTVILLE ALCOVY ALLEN ALTAVISTA AMERICUS ANGELINA

ESTIMATED SOIL PROPERTIES

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

SEPTIC TANK ABSORPTION
FIELDS

SEWAGE LAGOON AREAS

SHALLOW EXCAVATIONS

0.06-0.2 0.2-0.6 0.6-2.0 0.2-0.6 0.6-0.2 0.6-2.0 0.6-2.0 2.0-6.0 0.06-0.2

4.5-5.5

Low

4.5-5.5

Low

4.5-6.0

Low

4.5-5.5

Mod.

4.5-5.5

Low

4.5-5.5

Low

3.6-6.0

Low

4.5-5.5

Low

4.5-5.5

Low

Mod. High High Mod. Low Low Mod. Low High

Mod. High High High

>6.0

>60

0-1.0

>60

1.0-2.5

>60

>6.0

40-60

None
None Rare Occ None Rare Occ
None

High

2.0-3.0

>60

None

Mod.

>6.0

>60

Mod.

1.5-2.5

>60

High

>6.0

>60

High

+2-0

>60

None
None Rare Occ Freq
None
Occ Freq

B

0-15%: S; pk

0-7%: S; p

0-15%: S; cc

15+%: S; S, pk

7+%: S; s, cc

15+%: S; s, cc

D

None, Rare: S; w, pk None, Rare: S, -w, p

Occ: S, w, f, pk

Occ: S; w, f, p

S; w, cc

C

None, Rare: S; w None, Rare: S; w

Occ: S; w, f

Occ: S; w, f

S; w, cc

2-8%: M; cl

C

2-15%: S; pk

2-7%: M; s, r

8-15%: M; s, cl

15+%: S, s, pk

7+%: S; s

15+%: S; s

B

S; w, pk

S; w

2-8%: M; w

8+%: M; w, s

2-8%: M; pk

B

8-15%: M; s, pk

15+%: S; s

2-7%: M; s 7+%: S; s

2-8%: M: cl 8-15%: M; s, cl
15+%: S; s

None: S; w

C

None, Rare: S; w Rare, Occ, Freq:

S: w

Occ, Freq: S; w, f

S; w, f

0.8%: L

A

8-15%: M; s

0-15%: S; p

0-15%: S: cc

15+%: S; s

15+%: S; s, 0

15+%: S: s, cc

D

S; f, w

S; w

S; f, pk, w

LIMITATION OF SOILS FOR URBAN USES

DWELLINGS *w/basement #w/o basement
0-8%: L 8-15%: M; s 15+%: S; s
None: Sw Rare, Occ: S; w, f
None: S; w Rare, Occ: S; w, f
2-8%: M; ss 8-15%: M; ss, s
15+%: S; s
2-8%: M; w 8+%: M; w, s
2-8%: L 8-15%: M; s 15+%: S; s
None: M; w# None: S; w* Rare.Occ.Freq:
S; f, w
0-8%: L 8-15%: M; s 15+%: S; s
S; f

SMALL COMMERCIAL
BUILDINGS
0-4%: L 4-8%: M; s 8+%: S; s
None: S; w Rare: Occ: S; w, f
None: S; w Rare: Occ: S; w, f
2-4%: M; ss 4-8%: M; s, ss
8+%: S; s 2-4%: M; w 4-8%: M; w, s 8+%: S; s
2-4%: L 4-8%: M; s 8+%: S; s None: M; w Rare, Occ, Freq:
S; f 0-4%: L 4-8%: M; s 8+%: S; s
S; f

LOCAL ROADS AND
STREETS
0-8%: L 8-15%: M; s 15+%: S; s
None, Rare: S; w Occ: S; w, f
None, M; w Rare; M; w, f Occ: S; f
2-15%: S; b 15+%: S; s, b
2-8%: M; w 8+%: M; s 2-8%: M; b 8-15%: M; s, b 15+%: S; s None: M; w, b Rare: M; w, f, b Occ, Freq: S; f 0-8%: L 8-15%: M; s 15+%: S; s
S; f

ANGIE APISON APPLING ARAGON ARKAQUA

0.06-0.2 0.6-2.0 0.6-2.0 0.06-0.2 0.6-2.0

3.6-5.5 4.5-5.5 4.5-5.5

High Low Low

3.6-5.5 5.1-6.0

Mod. Low

High Mod. Mod. High High

Mod.

3.0-5.0

>60

None

Mod.

>6.0

20-40

None

Mod.

>6.0

>60

None

High

>6.0

>60

Mod.

1.5-2.0

>60

None Freq

D

S; pk, w

0-7%: S; w

0-8%: M; cl, w

7+%: S; s, w

8-12%: M; s, cl

2-7%: S; r

2-8%: M; r

B

S; r

7+%: S; s, r

8-15%: M; s, r

0-2%: M; p

B

0-8%: M; pk

2-7%: M; s, p

0-8%: M; cl

8-15%: M, s, pk

7+%: S; s

8-15%: M; s, cl

S; ss
2-8%: L# 2-8%: M; r* 8-12%: M; s
0-8%: L 8-15%: M; s

2-8%: M; cl

2-8%: M; ss

C

2-15%: S; pk

2-7%: M; s

8-15%: M; s, cl

8-15%: M; s, ss

15+%: S; s, pk

7+%: S; s

15+%: S; s

15+%: S; s

C

S; f, w

S; f, w

S; w

S; f# S; f, w*

0-8%: S; ss 8+%: S: s, ss
2-4%: L 4-8%: M: s 8+%: 5: s
0-4%: L 4-8%: M; s 8+%: S; s
2-4%: M; b 4-8%: M; s, ss
8+%: S; s
S; f

S; b, ss
2-8%: M; b 8-15%: M; s, b
0-8%: M; b 8-15%: M; s, b
2-15%: M; ss 15+%: S; b, s
S; b, f

ARDILLA ARMUCHEE ARUNDEL GaSWCC

0.2-0.6 0.2-0.6 >0.06

4.5-6.0

Low

4.5-5.5 3.6-5.5

Mod. High

High Mod. High

High

1.0-2.0

>60

None

Mod.

>6.0

20-36

None

High

>6.0

20-40

None

C

S; w, pk

S; w

S; w

S; w

5-8%: M; r, cl

5-8%: M; ss#, r*

C

5-15%: S; r

5-7%: S; r

8-15%: M; r, cl, s 8-15%: M; ss, s#, r*

15+%: S; r

7+%: S; s, r

15+%: S: s

15+%: S; s

2-8%: M; r, cl

C

2-15%: S; r, pk

2-7%: S; r

8-15%: M; r, cl, s

2-15%: S; ss

15+%: S; r, pk, s

7+%: S; r, s

15+%: S; s

15+%: S; ss, s

S; w
5-8%: M; ss, s 8+%: S; s
2-8%: S; ss 8+%: S; ss, s

M; w
5-15%: S; b 15%: S; b, s
2-15%: S; ss, b 15+%: S; ss, b, s
B-1-5

SOIL SERIES INTERPRETATIONS

SOIL SERIES

ESTIMATED SOIL PROPERTIES

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

SEPTIC TANK ABSORPTION
FIELDS

ASHE

2.0-6.0

4.5-6.0

Low

Low

High

>6.0

20-40

None

B

2-15%: S; r 15+%: S; s, r

SEWAGE LAGOON AREAS
2-7%: S; r, p 7+%: S; r, s, p

SHALLOW EXCAVATIONS
2-8%: M; r 8-15%: M; r, s
15+%: S; s

ASHLAR AUGUSTA

2.0-6.0 0.6-2.0

4.5-5.5

Low

4.5-6.0

Low

Low High

High Mod.

>6.0

20-40

1.0-2.0

>60

None
None Rare Occ Freq

B

0-15%: S; r

0-7%: S; r, p

0-15%: S; r

15+%: S; s

7+%: S; s, r, p

15+%: S; s, r

C

None, Rare: S: w None, Rare: S; w

S; w

Occ, Freq: S; W, f Occ, Freq: S; w, f

BARFIELD

0.2-0.6

6.1-7.8

High

High

Low

>6.0

8-20

None

D

1-15%: S; r 15+%: S; r, s

1-7%: S; r 7+%: S; s, r,

1-15%: S; r 15+%: S; r, s

BAYBORO BIBB BIGBEE

0.06-0.2 0.6-2.0 6.0-20

3.6-5.5

Mod.

High

High

0-0.5

>60

Occ

Freq

4.5-5.5

Low

4.5-6.0

Low

High

Mod.

0.5-1.5

>60

Occ

Freq

Rare

Low

Mod.

3.5-6.0

>60

Occ

Freq

D

S; w, pk, f

C

S; f, w

S; w, f S; f, w, p

A

Rare: S; w, pf

Rare: S; p

Occ, Freq; S; f, w, pf Occ, Freq: S; p, f

S; w S; f, w S; cc

BINNSVILLE BLADEN

0.06-0.2 0.06-0.2

7.4-8.4

Mod.

Mod.

Low

>6.0

7-20

None

D

Occ

3.6-5.5

Mod.

High

High

0-1.0

>60

Freq

D

1-15%: S, r 15+%: S, r, s
S; w, f

1-7%: S: r 7+%: S; r, s
L

1-15%: S; r 15+%: S; r, s
S; w

BLANTON BODINE BOHICKET

0.6-2.0 2.0-6.0 <0.06

0-8%: M; w

4.5-6.0

Low

High

High

4.0-6.0

>60

None

A

8-15%: M; w, s

0-7%: S; p

0-15%: S; cc

15+%: S; s

7+%: S; p, s

15+%: S; s, cc

5-8%: M; st t

3.6-5.5

Low

Low

High

>6.0

>60

None

B

8-15%: M; s, s

15+%: S; s

S; p, s

5-8%: M; st 8-15%: M; s, st
15+%: S; s

6.1-8.4

High

High

High

+3-0

>60

Freq

D

S; f, pk

S; f

S; f

LIMITATION OF SOILS FOR URBAN USES

DWELLINGS *w/basement #w/o basement
2-8%: M; r # 8-15%: M; r, s #
2-15%: S; r* 15+%: S; s# r*
0-15%: S; r* 0-15%: M; s, r#
15+%: S; s None: S; w Rare, Occ, Freq: S;
w, f
1-15%: S; r, ss 15+%: S; r, ss, s
S; w, f
S; w, cc

SMALL COMMERCIAL
BUILDINGS
2-4%: M; r 4-8%: M; r, s
8+%: S; s 0-4%: M; r 4-8%: M; r, s 8+%: S; s None: S; w Rare, Occ, Freq: S;
w, f
1-8%: S; ss, r 8+%: S; ss, r, s
S; w, f
S; f, w

LOCAL ROADS AND
STREETS
2-8%: M; r 8-15%: M; s, r
15+%: S; s 0-8%: M; r 8-15%: M; s, r 15+%: S; s None: M; w, b Rare: M; w, b, f Occ, Freq: S; f
1-15%: S; r, b 15+%: S; r, b, s
S; w, b, f
S; f, w

S; f
1-8%: Mod; ss, r # 8-15%: Mod: ss, r, s# 1-15%: S; r* 15+%: S; S#r*
S; w, f
0-8%: L 8-15%: M; s 15+%: S; s 5-8%: M; st 8-15%: M; s, st 15+%: S; s
S; f, ss

S; f
1-4%: M; ss, r 4-8%: M; ss, r, s
8+%: S; sS;
w, f
0-4%: L 4-8%: M; s 8-12%: S; s
8%: M; st 8+%: S; s
S; f, ss

Rare: M; f Occ, Freq: S; f
1-15%: S; b 15+%: S; b, s
S; w, f, b
0-8%: L 8-15%: M; s 15+%: S; s 5-8%: M; st 8-15%: M; s, st 15+%: S; s
S; f, ss, b

BONIFAY BONNEAU BOSWELL BRADDOCK BRADSON GaSWCC

0.2-0.6 0.6-2.0 <0.06 0.6-2.0 0.6-2.0

4.5-6.5

Low

Low

High

4.0-5.0

>60

None

4.5-5.5

Low

Low

High

3.5-5.0

>60

None

4.5-5.5

High

High

Mod.

>6.0

>60

None

3.6-5.5

Mod.

High

Mod.

>6.0

>60

None

4.5-6.0

Low

High

Mod.

>6.0

>60

None

A

0-8%: M; w, pk

0-7%: S; p

8-12%: M; w, pk, s

7+%: S; p, s

A

S; w

0-7%: S; p

7+%: S; p, s

1-2%: L

D

S; pk

2-7%: M; s

7+%: S; s

0-8%: M; pk

B

8-15%: M; pk.s

0-7%: S; p

15+%: S; s

7+%: S; s, p

2-8%: L

B

8-15%: M; s

2-7%: M; s

15+%: S; s

7+%: s; s

S; cc
S; cc
1-8%: M; cl 8-15%: M; cl, s
15+%: S; s 0-8%: M; cl 8-15%: M; cl, s 15+%: S; s 1-8%: M; cl 8-15%: M; cl, s 15+%: S; s

0-8%: L# 0-8%: M; w* 8-12%: M; s#, w*
0-8%: L# 0-8%: M; w* 8-12%: M; s#, w*
1-15%: S; ss 15+%: S; s, ss
0-8%: M; ss 8-15%: M; ss, s
15+%: S; s 2-8%: L
8-15%: M; s 8+%: S; s

0-4%: L 4-8%: M; s 8+%: S; s
0-4%: L 4, 8%: M; s 8+%: S; s
1-8%: S; ss 8+%: S; s, ss
0-4%: M; ss 4-8%: M; ss, s
8+%: S; s
2-4%: L 4-8%: M; s

0-8%: L 8-12%: M; s
0-8%: L 8-12%: M; s
1-15%: S; ss, b 15+%: S; s, ss, b
0-15%: S; b 15+%: S; s, b
2-15%: S; b 15+%: S; b, s
B-1-7

SOIL SERIES INTERPRETATIONS

SOIL SERIES BRASSTOWN BREVARD BROOKMAN BUNCOMBE

ESTIMATED SOIL PROPERTIES

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

SEPTIC TANK ABSORPTION
FIELDS

0.6-2.0 0.6-2.0 0.06-0.2 6.0-20

4.5-6.0

Low

4.5-6.0

Low

4.5-7.8

Mod.

4.5-6.0

Low

Mod. Mod. Mod. Low

High Mod. Mod. Mod.

>6.0 >6.0 0-1.0 >6.0

40-60

None

>60

None

>60

None Rare Occ Freq

Rare

>60

Occ

Freq

2-8%: M; r, pk

B

8-15%: M; r, pk, s

15+%: S; s

2-8%: L

B

8-15%: M; s

15+%: S; s

D

None, Rare: S; w, pk

Occ, Freq: S; f, w, pk

A

Rare: S; pf

Occ, Freq: S, f, pf

SEWAGE LAGOON AREAS
2-7%: M; r, s 7+%: S; s
2-7%: M; p, s 7+%: S; s
L
S; p, f

SHALLOW EXCAVATIONS
2-8%: L 8-15%: M; s 15+%: S; s
2-8%: L 8-15%: M; s 15+%: S; s
S; w
S; cc

BURTON CAHABA

0.6-6.0 0.6-2.0

3.6-6.0

Low

High

High

>6.0

20-40

None

B

None

4.5-6.0

Low

Mod.

Mod.

>6.0

>60

Rare

B

Occ

5-%: S; r 15+%: S; r, s
None: L Rare: M; f Occ: S; f

5-7%: S; p, r 7+%: S; p, r, s
None, Rare: S; P Occ: S; p, f

5-15%: S; r 15+%: S; r, s
S; cc

CAINHOY CAPE FEAR

<0.06 0.06-0.2

6.6-8.4

High

High

High

+1-1.0

>60

Freq

A

None

4.5-6.0

Mod.

High

High

0-1.5

>60

Rare

D

S; pf S; w, pk

0-7%: S; p 7+%: S; p, s
None: S; p, w Rare: S; p, w, f

S; cc S; w

LIMITATION OF SOILS FOR URBAN USES

DWELLINGS *w/basement #w/o basement
2-8%: L 8-15%: M; s 15+%: S; s
2-8%: L 8-15%: M; s 15+%: S; s None: S; w Rare, Occ, Freq: S;
f, w
S; f
5-15%: M; r# 5-15%: S; r* 15+%: S; s#, r*
None: L Rare, Occ: S; f
0-8%: L 8-10%: M; s
None: S; w Rare: S; w, f

SMALL COMMERCIAL
BUILDINGS
2-4%: L 4-8%: M; s 8+%: S; s
2-4%: L 4-8%: M; s 8+%: S; s None: S; w Rare, Occ, Freq: S;
f, w
S; f
5-8%: M; s, r 8+%: S; s
None: L Rare: Occ: S; f
0-4%: L 4-8%: M; s 8+%: S; s
None: S; w Rare: S; w, f

LOCAL ROADS AND
STREETS
2-8%: M; b 8-15%: M; b, s
15+%: S; s 2-8%: L
8-15%: M; s 15+%: S; s None, Rare: S; b, w Occ, Freq: S; f, w, b
Rare: M; f Occ, Freq: S, f
5-8%: M; r 8-15%: M; s, r
15+%: S; s
None: L Rare: M; f Occ: S, f
0-8%: L 8-10%: M; s
S; b, w

CAPERS

<0.06

6.6-8.4

High

High

High

+1-1.0

>60

Freq

D

S; w, f, pk

S; f, w

S; f, w

S; f, w, ss

S; f, w, ss

S; f, b, w

0-2%: M; r

0-8%: M; ss#

0-4%: M; ss

CAPSHAW

0.06-0.2

5.1-7.8

Mod.

High

Mod.

3.5-5.0

48>60

None

C

S; pk

2-7%: M; s, r

M; r, w, cl

8-12%: M; ss, s#

4-8%: M; s, ss

S; b

7+%: S; s

M; ss, w*r

8+%: S; s

CARNEGIE CARTECAY CATASKA CECIL

0.2-0.6 2.0-6.0 2.0-20 0.6-0.2

4.5-5.5

Low

5.1-6.5

Low

4.5-5.5

Low

4.5-5.5

Low

Low Low Low Mod.

Mod. Mod. Mod.

>6.0

>60

0.5-1.5

>60

>6.0

20-40

None Occ Freq
None

Mod.

>6.0

>60

None

C

S; pk

2-7%: M; s 7+%: S; s

2-8%: M; cl, d 8-12%: M; s, cl, d

2-8%: M; s 8-12%: M; s

C

S; w, f

S; w, p, f

S; w, cc

S; f, w

D

10-15%: S; r

15+%: S; r, s

S; p, r, s

10-15%: S; r 15+%: S; r, s

10-15%: M; s, r# 10-15%: S; r* 15+%: S; s#r*

0-8%: M; pk

0-2%: M; p, s

0.8%: M; cl

B

8-15%: M; pk, s

2-7%: M; p

8-15%: M; cl, s

15+%: S; s

7+%: S; s

15+%: S; s

0-8%: L 8-15%: M; s 15+%: S; s

2-8%: M; s 8-12%: S; s
S; f, w
S; s
0-4%: L 4-18%: M; s 8+%: S; s

0-8%: M; b 8-12%: M; s, b
S; f, w
10-15%: M; r, s 15+%: S; s 0-8%: M; b
0-15%: M; b, s 15+%: S; s

CEDARBLUFF

0.06-0.2

5.1-6.0

Mod.

High

Mod.

0.5-1.0

>60

Freq

C

S; f, pk, w

L

S; w

S; f, w

S; f, w

S; f, w, b

M; w*

CENTENARY

2.0-0.6

4.5-6.0

Low

Mod.

High

3.5-5.0

>60

None

A

S; w, p, f

S; p

S; cc

L#

L

L

CHANDLER

2.0-0.6

4.5-6.0

Low

Low

High

>6.0

>60

None

B

S; s

S; s

S; s

S; s

GaSWCC

S; s

S; s, b

B-1-9

SOIL SERIES INTERPRETATIONS

SOIL SERIES CHASTAIN

ESTIMATED SOIL PROPERTIES

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

0.06-0.2

Occ

D

4.5-6.0

Mod.

High

High

0-1.0

>60

Freq

SEPTIC TANK ABSORPTION
FIELDS
S; f, w, pk

SEWAGE LAGOON AREAS
S; f, p

LIMITATION OF SOILS FOR URBAN USES

SHALLOW EXCAVATIONS
S; w, cc

DWELLINGS *w/basement #w/o basement
S; f, w

SMALL COMMERCIAL
BUILDINGS
S; f, w

LOCAL ROADS AND
STREETS
S; f, w,b

CHATUGE CHENNEBY CHESTATEE CHEWACLA CHIPLEY CHIPOLA CHISOLM CLARENDON CLIFTON COLFAX COLVARD CONASAUGA CONGAREE COOSAW COWARTS COWEE GaSWCC

0.6-2.0 0.6-2.0 0.6-2.0 0.6-2.0 6.0-2.0 2.0-6.0 0.6-2.0 0.2-2.0 0.6-2.0 0.06-0.2 2.0-6.0 0.06-0.2 0.6-2.0 0.6-2.0 0.06-0.6 0.6-2.0

4.5-6.0

Mod.

4.5-6.0

Low

4.5-5.5

Low

14.5-7.8

Low

4.5-6.0 4.5-5.5 4.5-6.0

Low Low Low

4.5-5.5

Low

4.5-6.5

Low

4.5-5.5 5.1-7.8

Mod. Low

3.6-6.5

Mod.

4.5-7.3

Low

4.5-5.5

Low

4.5-5.5

Low

4.5-6.0

Low

High High High High Low Low Low Mod. Low High Low High Mod. Mod. Mod. Mod.

High

1.0-2.0

>60

Mod.

1.0-2.5

>60

High

>6.0

>60

Mod.

0.5-1.5

>60

High

2.0-3.0

>60

High

>6.0

>60

High

3.0-5.0

>60

Occ
Occ Freq
None Rare Occ Freq None
None
None

High

2.0-3.0

>60

Mod.

>6.0

>60

None None

High

0.5-1.5

>60

Mod.

4.0-6.0

>60

None Occ

High Mod. High Mod.

>6.0

20-40

2.5-4.0

>60

2.0-3.0

>60

>6.0

>60

None
None Rare Occ Freq
None
None

High

>6.0

20-40

None

D

S; w, f

C

S; f, w

S; w, f, p S; p, f, w

S; w, f S; w

S; w, f S; f, w

2-8%: M; st

2-8%: M; st

2-8%: M; st

B

8-10%: M; s, st

2-7%: M; s

8-15%: M; s, st

8-15%: M; s, st

15+%: S; s

7+%: S; s

15+%: S; s

15+%: S; s

C

Rare: S; s

Rare: S; w

Occ, Freq: S; f, w Occ, Freq: S; f, w

C

S; w, pf

S; p, w

S; w S; cc, w

S; w, f
M; w# S; w*

A

L

0-7%: S; p

7+%: S; p, s

A

0-8%: M; w

0-7%: S; p, w

8-10%: M; w, s

7+%: S; p, w, s

C

S; pk, w

S; w

S; cc S; cc S; w

L
0-8%: L# 0-8%: M; w* 8-10%: M; s#, w*
M; w# S; w*

2-8%: M; pk

2-8%: M; cl

B

8-15%: M; pk, s

2-7%: S; p

8-15%: M; cl, s

15+%: S; s

7+%: S; p, s

15+%: S; s

2-8%: L 8-15%: M; s 15+%: S; s

C

S; pK, w

0-7%: S; w

S; w

S; w

7+%:S;w,s

B

S; f

S; p, f

S; cc

S; f

0-8%: M; r, cl

0-8%: M; ss

C

0-15%: S; pk, r

0-7%: S; r, s

8-15%: M; s, r, cl

8-15%: M; s, ss

15+%: S; s, pk

7+%: S; s, r

15+%: S; s

15+%: S; s

None: S; w

None: L#

B

None, Rare: S; w Rare, Occ, Freq: S; None, Rare: M; w

None: M; w*

Occ, Freq: S; w

w, f

Occ, Freq: M; w, f

Occ, Freq: S; f

B

S; w, pf

S; w, p

S; w, cc

M; w# S; w*

C

S; pk

2-7%: M; s

2-8%: L

2-8%: L

7+%: S; s

8-15%: M; s

8-15%: M; s

B

8-15%: S; r

15+%: S; r, s

S; r, s

8-15%: M; r, s 15+%: S; s

8-15%: M; s# 8-15%: M; r, s*
15+%: S; s

S; w, f
S; f, w
2-4%: M; st 4+%: S; s
S; w, f
0-4%: M; w 4-8%: M; s, w
0-4%: L 4-8%: M; s
0-4%: L 4-8%: M; s 8+%: S; s
M; w
2-4%: L 4-8%: M; s 8+%: S; s
0-4%: S; w 4+%:S;s
S; f
0-4%: M; ss 4-8%: M; s, ss
8+%: S; s None: L Rare, Occ, Freq:
S; f
M; w
2-4%: L 4-8%: M; s 8+%: S; s
S; s

S; w, f,
S; b, f
2-8%: M; st 8-15%: M; s, st, b
15+%: S; s Rare: S; w, b Occ, Freq: S; w, f, b
M; w
L
0-8%: L 8-10%: M; s
M; w
2-15%: S; b 15+%: S; b, s
M; w
S; f
0-15%: S; b 15+%: S; s, b None: M; b Rare: M; b, f Occ, Freq: S, f
M; w
2-8%: L 8-15%: M; s
8-15%: M; s 15+%: S; s
B-1-11

SOIL SERIES INTERPRETATIONS

SOIL SERIES

ESTIMATED SOIL PROPERTIES

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

SEPTIC TANK ABSORPTION
FIELDS

SEWAGE LAGOON AREAS

LIMITATION OF SOILS FOR URBAN USES

SHALLOW EXCAVATIONS

DWELLINGS *w/basement #w/o basement

SMALL COMMERCIAL
BUILDINGS

LOCAL ROADS AND
STREETS

COXVILLE CRAVEN CUNNINGHAM CUTHBERT DASHER DAVIDSON DECATUR DEKALB DEWEY DILLARD DOCENA DOGUE DOTHAN DOWELLTON DUCKSTON

0.2-0.6 0.06-0.2 0.06-0.2 0.06-0.6 2.0-6.0 0.6-2.0 0.6-2.0 6.0-2.0 0.6-2.0 0.2-0.6 0.06-0.6 0.2-0.6 0.2-0.6 0.06-0.2
>20

3.6-5.5

Mod.

3.6-5.5

Mod.

4.5-5.5

Mod.

3.6-5.5

Mod.

3.6-4.4

Low

4.5-6.0

Low

4.5-6.0 3.6-5.5

Mod. Low

4.5-5.5

Mod.

4.5-5.5

Mod.

4.5-6.0

Mod.

3.6-5.5

Mod.

4.5-6.0

Low

5.1-7.8

High

3.6-8.4

Low

High High High High High High High Low High Mod. Mod. High Mod. High Low

High

0-1.5

>60

None

High

2.0-3.0

>60

None

High

>6.0

40-60

None

High

>6.0

>60

None

High

+3-0.5

>60

None

Mod.

>6.0

>60

None

Mod.

>6.0

>60

None

High

>6.0

20-40

None

Mod.

>6.0

>60

High

2.0-3.0

>60

Mod.

1.5-3.0

>60

High

1.5-3.0

>60

Mod.

3.0-5.0

>60

None
None Rare None Rare Occ
None Rare
None

Mod. Low

0.5-1.0

40-60

1.0-2.0

>60

None
Freq Occ

D

S; w, pk

S; w

S; w

S; w

0-2%: M; p

0-8%: M; w, ss#

C

S; pk, w

2-7%: M; p, s

S; w, cc

8-12%: M; w, ss, s#

7+%: S; s

S; w*

2-8%: M; cl

2-8%: M; ss

C

2-15%: S; pk

2-7%: M; s, r

8-15%: M; cl, s

8-15%: M; ss, s

15+%: S; pk, s

7+%: S; s

15+%: S; s

15+%: S; s

5-8%: M; cl

5-8%: M; ss

C

5-15%: S; pk

5-7%: M; s

8-15%: M; cl, s

8-15%: M; ss, s

15+%: S; pk, s

7+%: S; s

15+%: S; s

15+%: S; s

D

S; w, u

S; w, h

S; w, h

S; w, b

2-8%: M; pk

2-8%: M; cl

B

8-15%: M; pk, s

2-7%: M; p, s

8-15%: M; s, cl

15+%: S; s

7+%: S; s

15+%: S; s

2-8%: L 8-15%: M; s 15+%: S; s

1-8%: L

1-8%: M; cl

1-8%: M; ss

B

8-15%: M; s

1-7%: M; p, s

8-15%: S; s

8-15%: M; s, ss

15+%: S; s

7+%: S; s

15+%: S; s

15+%: S; s

C

0-15%: S; pf, r

0-7%: S; r, p

0-15%: S; r

15+%: S; pf, r, s

7+%: S; r, s, p

15+%: S; r, s

0-8%: M; r, st# 8-15%: M; r, sts#
0-15%: S; r* 15+%: S; s# 15+%: S; s, r

2-8%: M; pk

2-8%: M; cl

2-8%: M; ss

B

8- 15%: M; s, pk

2-7%: M: p, s

8-15%: M; s, cl

8-15%: M; s, ss

15+%: S; s

7+%: S; s

15+%: S; s

15+%: S; s

C

S; w, pk

2-7%: S; w

S; w

7+%: S; s

None: M; w# None: S; w*
Rare: S; f

C

None, Rare: S; w, pk

None: S; w

S; w

Occ: S; f, w, pk

Rare, Occ: S; f, w

None: M; w# None: S; w* Rare, Occ: S; w, f

0-7%: None: S; p, w

0-15%: None: M; ss, w#

C

S; w, pk

7+%: None: S; p, w, s 0-7%: Rare: S; p, f, w

S; cc, w

0-15%: Rare: S, f# None: S; w*

7+%: Rare: S; p, f, s

Rare: S; f, w#

0-2%: L

0-8%: L#

B

M; pk, w

2-7%: M; s

0-8%: M; w

8-12%: M; s#

7+%: S; s

8-12%: M; w, s

0-8%: M; w* 8-10%: M; s*

D

S; w, pk

S; w

S; w, cl

S; w, ss

A/D

S; w, f, pf

S; w, f, p

S; w, cc

S, w, f

S; w
0-4%: M; w, ss 4-8%: M; w, ss, s
8+%: S; s 2-8%: M; ss 4-8%: M; ss, s 8+%: S; s
5-8%: M; s, ss 8+%: S; s
S; w, b
2-4%: L 4-8%: M; s 8+%: S; s 1-4%: M; ss 4-8%: M; s, ss 8+%: S; s 0-4%: M; r, st 4-8%: M; r, st, s 8+%: S; s 2-4%: M; ss 4-8%: M; s, ss 8+%: S; s
None: M; w, s Rare: s; f
0-4%: None: M; w 4-6%None: M; w, s
Rare, Occ: S; f
8%None: M; ss, w, s# 8+%: None: S; s# 0-8%: Rare: S; f* 8+%: Rare: S; f, s*
0-4%: L 4-8%: M; s 8+%: S; s
S; w, ss
S; w, f

S; w, b
S; b
2-15%: S; b 15+%: S; s, b
5-15%: S; b 15+%: S; b, s
S; w
2-15%: S; b 15+%: S; b, s 1-8%: M; b 8-15%: M; s, b 15+%: S; s 0-8%: M; r, st 8-15%: M; r, st, s 15+%: S; s 2-15%: S; b 15+%: S; s, b
S; b
None: Rare: S; b Occ: S; b, f
S; b
0-8%: L 8-10%: M; s
S; w, ss, b
S; f

DUNBAR

0.2-0.6

4.5-5.5

Mod.

High

High

1.0-2.5

>60

None

D

S; w, pk

S; w

S; w

DUPLIN GaSWCC

0.2-0.6

4.5-5.5

Mod.

High

High

2.0-3.0

>60

None

C

S; w

M; w

S; w
M; w# S; w*

S; w
0-4%: M; w 4-8%: M; s, w

S; b S; b
B-1-13

SOIL SERIES INTERPRETATIONS

SOIL SERIES

ESTIMATED SOIL PROPERTIES

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

SEPTIC TANK ABSORPTION
FIELDS

DURHAM DYKE ECHAW EDGEMONT EDNEYTOWN EDNEYVILLE

0.6-2.0 0.6-2.0 2.0-20 0.6-6.0 0.6-2.0 0.6-2.0

4.5-5.5

Low

4.5-6.0 4.5-6.0 3.6-5.5 4.5-5.5

Mod. Low Low Low

4.5-6.0

Low

Mod. High Low Low Mod. Low

Mod.

>6.0

>60

Mod.

>6.0

>60

High

2.5-5.0

>60

High

>6.0

>40

Mod.

>6.0

>60

High

>6.0

>60

None None None None None None

B

0-8%: L

8-10%: M; s

0-8%: M; pk

B

8-15%: M; pk, s

15+%: S; s

A

S; w, pf

0-8%: M; r, pk

B

8-15%: M; r, pk, s

15+%: S; s

2.8%: L

B

8-15%: M; S

15+%: S; s

6-8%: L

B

8-15%: M; S

15+%: S; S

SEWAGE LAGOON AREAS
0-2%: M; p 2-7%: M; s 7+%: S; s
0-2%: M; p 2-7%: M; s, s
7+%: S; s
S; p, w

SHALLOW EXCAVATIONS
0-8%: L 8-10%: M; s 0-8%: M; cl 8-15%: M; cl, s 15+%: S; s
M; cc

0-7%: S; p 7+%: S; p, s
2-7%: S; p 7+%: S; p, s
S; s

0-15%: S; cc 15+%: S; cc, s
2-15%: S; cc 15+%: S; cc, s
6-8%: L 8-15%: M; s 15+%: S; s

ELLABELLE EMORY ENDERS ENNIS ENON ESTO ETOWAH EUHARLEE

0.6-2.0 0.6-2.0 <0.06 2.0-6.0 0.06-0.2 0.06-0.2 0.6-2.0 0.2-0.6

4.5-5.5

Low

5.1-6.0

Low

3.6-5.5

High

4.5-6.0

Low

5.1-7.8

High

4.5-5.5

Mod.

4.5-5.5

Low

4.5-5.5

Low

High Mod. High Low High High Low Mod.

High Mod. High Mod. Mod.

+1-0.5

>60

5.0-6.0

>60

>6.0

40-60

>6.0

>60

>6.0

>60

Freq None Rare Occ
None
Rare Occ
None

High

>6.0

>60

None

Mod.

>6.0

High

>6.0

>60

None

>60

None

C

S; f, w

S; f, w

S; w, cc

None: M; pk, w

0-2%: None: M; p

B

Rare: M; f, w, pk 2-5%: None: M; p, s None, Rare: L

Occ: S; f

Rare, Occ: S; f

Occ: M; f

1-8%: M; cl

C

1-15%: S; pk

1-7%: M; s, r

8-15%: M; cl, s

15+%: S; s, pk

7+%: S; s

15+%: S; s

Rare: M; f

B

Occ: S; f

Rare: L Occ: M; f

2-8%: M; cl

C

2-15%: S; pk

2-7%: M; s

8-15%: M; cl, s

15+%: S; pk, s

7+%: S; s

15+%: S; s

0-8%: M; cl

B

2-15%: S; pk

2-7%: M; s

8-15%: M; cl, s

15+%: S; pk, s

7+%: S; s

15+%: S; s

0-8%: M; pk

0-2%: M; p

2-8%: M; cl

B

8-15%: M; s; pk

2-7%: M; s, p

8-15%: M; s, cl

15+%: S; s

7+%: S; s

15+%: S; s

C

S; pk

2-7%: M; s

2-8%: M; cl

7+%: S; s

8-10%: M; s, cl

EULONIA EUNOLA EUSTIS GaSWCC

0.2-0.6 0.6-2.0 6.0-20

4.5-6.5

Low

4.5-5.5

Low

4.5-5.5

Low

Mod. Low Low

High

1.5-3.5

>60

High

1.5-2.5

>60

High

>6.0

>60

None
None Rare Occ
None

C

S; pk, w

L

S; w

C

None, Rare: S; w None, Rare: S; w, p

S; w, cc

Occ: S; w, f

Occ: S, w, e, f

0-8%: L

A

8-15%: M; s

0-7%: S; p

0-15%: S; cc

15+%: S; s

7+%: S; p, s

15+%: S; s

LIMITATION OF SOILS FOR URBAN USES

DWELLINGS *w/basement #w/o basement
0-8%: L 8-10%: M; s
0-8%: M; ss 8-15%: M; s, ss
15+%: S; s L#
M; w*
0-8%: L# 0-8%: M; r* r* 8-15%: M; s# 15+%: S; s
2-8%: L 8-15%: M; s 15+%: S; s
6-8%: L 8-15%: M; s 15+%: S; s
S; f, w
None: L# None: M; w* Rare, Occ: S; f
1-15%: S; ss 15+%: S; s, ss
S; f
2-15%: S; ss 15+%: S; ss, s
2-8%: M; ss 8-15%: M; ss, s
15+%: S; s
0-8%: L 8-15%: M; s 15+%: S; s
2-8%: L 8-10%: M; s
M; w# S; w*
None: M; w# None: S; w*
Occ: S; f 0-8%: L 8-15%: M; s 15+%: S; s

SMALL COMMERCIAL
BUILDINGS
0-4%: L 4-8%: M; s 8+%: S; s 0-4%: M; ss 4-8%: M; ss, s 8+%: S; s
L
0-4%: L 4-8%: M; s 8+%: S; s
2-4%: L 4-8%: M; s 8+%: S; s
6-8%: M; s 8+%: S; s
S; f, w
None: L Rare: Occ: S; f
1-8%: S; ss 8+%: S; s, ss
S; f
2-8%: S; ss 8+%: S; ss, s 2-4%: M; ss 4-8%: M; ss, s
8+%: S; s 0-4%: L 4-8%: M; s 8+%: S; s 2-4%: L 4-8%: M; s 8+%: S; s
0-4%: M; w 4-6%: M; w, s
None: M; w Rare, Occ: S; f
0-4%: L 4-8%: M; s 8+%: S; s

LOCAL ROADS AND
STREETS
0-8%: L 8-10%: M; s
0-15%: S; b 15+%: S; s, b
L
0-8%: L 8-15%: M; s 15+%: S; s
2-8%: L 8-15%: M; s 15+%: S; s
6-8%: L 8-15%: M; s 15+%: S; s
S; f, w
None, Rare: S; b Occ: S; b, f
1-15%: S; b, ss 15+%: S; s, b, ss
Rare: M; f Occ: S; f
2-15%: S; b, ss 15+%: S; b, ss, s
2-15%: S; b 15+%: S; b, s 0-8%: M; b 8-15%: M; s, b 15+%: S; s
2-8%: S; b 8-10%: S; s, b
M; b, w
None: M; w Rare: M; wf
Occ: S; f 0-8%: L 8-15%: M; s 15+%: S; s
B-1-15

SOIL SERIES INTERPRETATIONS

SOIL SERIES

ESTIMATED SOIL PROPERTIES

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

SEPTIC TANK ABSORPTION
FIELDS

EUTAW EVARD FACEVILLE FANNIN FARRAGUT FLOMATION FOXWOTH

<0.06 0.6-2.0 0.6-2.0 0.6-2.0 0.2-0.6 6.0-2.0
>20

4.5-7.8

High

4.5-6.0

Low

4.5-6.0

Low

4.5-6.0

Low

4.5-5.5

Mod.

4.5-6.0

Low

4.5-6.0

Low

High Mod. Low Mod. High Low Low

Mod.

0.5-1.5

>60

High

>6.0

>60

Mod.

>6.0

>60

Mod.

>6.0

>60

Mod.

>6.0

>48

Mod.

>6.0

>60

High

3.5-6.0

>60

None None None None None None None

C

S; pk, w

2-8%: L

B

8-15%: M; s

15+%: S; s

B

0-8%: L

8-15%: M; s

2-8%: M; pk

B

8-15%: M; s, pk

15+%: S; s

C

2-15%: S; pk

15+%: S; s, pk

A

2-15%: S; pf

15+%: S; pf, s

A

M; w

FREEMANVILLE FRENCH

0.2-0.6 0.6-2.0

5.1-6.0

Low

Mod.

Mod.

>6.0

>60

None

B

Occ

5.1-6.5

Low

Mod.

Mod.

1.0-2.5

>60

Freq

C

S; pk S; f, w

FRIPP FULLERTON FUQUAY GALESTOWN GAYLESVILLE GEORGEVILLE GILEAD

6.0-2.0 0.6-2.0 0.06-0.2
>6.0 0.06-0.2 0.6-2.0 0.06-0.6

5.6-7.8 4.5-5.5

Low Mod.

4.5-6.0

Low

3.6-5.5

Low

3.6-6.0 4.5-5.5 4.5-5.5

Mod. Low Low

Low High Low Low High High Mod.

Low

>6.0

Mod.

>6.0

>60

None

Rare

>60

None

High

4.0-6.0

>60

None

High

>6.0

>60

None

High

0-1.5

>60

High

>6.0

>60

High

1.5-2.5

>60

Freq None None

A

2-15%: S; pf

15+%: S; pf, s

2-8%: M; pk

B

8-15%: S; s

15+%: M; pk, s

B

0-8%: M; pk

8-10%: M; pk, s

A

0-15%: S; pf

15+%: S; pf, s

D

S; f, w, pk

2-8%: M; pk

B

8-15: M; s, pk

15+%: S; s

C

S; pk, w

GILPIN GaSWCC

0.6-2.0

3.6-5.5

Low

Low

High

>6.0

20-40

None

C

0-15%: S; r 15+%: S; r, s

LIMITATION OF SOILS FOR URBAN USES

SEWAGE LAGOON AREAS
L

SHALLOW EXCAVATIONS
S; w

2-7%: M; p, s 7+%: S; s 0-2%: M; p
2-7%: M; s, p 7+%: S; s
2-7%: M; p, s 7+%: S; s
2-7%: M; s, s 7+%: S; s
2-7%: S; p 7+%: S; p, s
0-7%: S; s 7+%: S; p, s
0-2%: L 2-7%: M; s 7+%: S; s
S; f, w

2-15%: S; cc 15%+: S; cc, s
0-8%: M; cl 8-15%: M; cl, s
2-8%: L 8-15%: M; s 15+%: S; s 2-8%: M; cl, s 8-15%: M; cl, s 15+%: S; s
2-15%: S; cc 15+%: S; cc, s
S; cc
0-8%: M; cl 8-12%: M; cl, s
S; cc, w

DWELLINGS *w/basement #w/o basement
M; w# S; w*
2-8%: L 8-15%: M; s 15+%: S; s
0-8%: L 8-15%: M; s
2-8%: L 8-15%: M; s 15+%: S; s 2-8%: M; ss 8-15%: M; s, ss 8+%: S; s
2-8%: L 8-15%: M; s 15+%: S; s
L# M; w*
0-8%: L 8-12%: M; s
S; f, w

2-7%: S; p 7+%: S; s, p
2-7%: M; p, s 7+%: S: s 0-2%: L 2-7%: M; s 7+%: S; s
0-7%S; p 7+%: S; p, s

2-15%: S; cc 15+%: S; c, s 2-8%: M; cl 8-15%: M; cl, s 15+%: S; s
0-8%: L 8-10%: M; s
0-15%: S; cc 15+%: S; cc, s

2-15%: None: M; s 15+%: None: S; s 2-15%: Rare: S; f 15+%: Rare: S; f, s
2-8%: M; ss 8-15%: None: M; s, ss
15+%: S; s
0-8%: L# 8-10%: M; s# 0-8%: M; w* 8-10%: M; w, s*
0-8%: L 8-15%: M; s 15+%: S: s

L
2-7%: M; s, p 7+%: S; s 0-2%: L 2-7%: M; s 7+%: S; s
0-7%: S; r 7+%: S; r, s

S; w
2-8%: M; cl 8-15%: M; s, cl
15+%: S; s
S; w
0-8%: M; r 8-15%: M; r, s
15+%: S; s

S; w, f
2-8%: L 8-15%: M; s 15+%: S; s 0-8%: M; w# 8-15%: M; s, w#
S; w*
0-8%: L# 0-8%: M; r* 8-15%: M; s#, r* 15+%: S; s

SMALL COMMERCIAL
BUILDINGS
0-4%: M; w 4-6%: M; w, s
2-4%: L 4-8%: M; s 8+%: S; s
0-4%: L 4-8%: M; s 8+%: S; s
2-4%: L 4-8%: M; s 8+%: S; s 2-4%: M; ss 4-8%: M; s, ss 8+%: S; s
2-4%: L 4-8%: M; s 8+%: S; s
0-4%: L 4-8%: M; s
0-4%: L 4-8%: M; s 8+%: S; s
S; f, w
2-8%: None: M; s 8+%: None: S; s 2-8%: Rare: S; f 8+%: Rare: S; f, s
2-4%: M; ss 4-8%: M; s, ss s
8+%: S; 0-4%; L 4-8%: M; s 8+%: S; s 0-4%: L 4-8%: M; s 8+%: S; s
S; w, f
2-4: L 4-8%: M; s 8+%: S; s 0-4%: M; w 4-8%: M; s, w 8+%: S; s
0-4%: L 4-8%: M; s 8+%: S; s

LOCAL ROADS AND
STREETS
M; b, w
2-8%: L 8-15%: M; s 15+%: S; s
0-8%: M; b 8-15%: M; s, b
2-15%: S; b 15+%: S; b, s
2-15%: S; b 15+%: S; s, b
2-8%: L 8-15%: M; s 15+%: S; s
L
0-8%: M; b 8-12%: M; b, s
S;f
2-15%: None: M; s 2-15%: Rare: M; f, s
2-8%: M; ss, b 8-15%: M; ss, b, s 15+%: M; ss, b, s
0-8%: L 8-10%: M; s
0-8%: L 8-15%: M; s 15+%: S: s
S; w, f, b
2-15%: S; b 15+%: S; s, b
S; b
0-8%: L 8-15%: M; s 15+%: S; s
B-1-17

SOIL SERIES INTERPRETATIONS

SOIL SERIES

ESTIMATED SOIL PROPERTIES

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

SEPTIC TANK ABSORPTION
FIELDS

GOLDSBORO

0.6-2.0

3.6-5.5

Low

Mod.

High

2.0-3.0

>60

None

B

S; w

GOLDSTON

2.0-6.0

3.6-5.5

Low

Mod.

High

>6.0

. 10-20

None

C

2-15%: S; r 15+%: S; r, s

LIMITATION OF SOILS FOR URBAN USES

SEWAGE LAGOON AREAS
S; w

SHALLOW EXCAVATIONS
S; w

2-7%: S; r, p 7+%: S; r, s, p

2-15%: S; r 15+%: S; r, s

DWELLINGS *w/basement #w/o basement
M; w# S; w*
2-15%: M; r, s# 15+%: S; s S; r*

SMALL COMMERCIAL
BUILDINGS
0-4%: M; w 4-8%: M; s, w 2-4%: M; r, s# 4-8%: M; s, r, st
8+%: S; s

LOCAL ROADS AND
STREETS
M; w
2-8%: M; r, st 8-15%: S; s 15+%: S; s

GORGAS GRADY GREENVILLE GRITNEY GROVER GUTHRIE GWINNETT HAMBLEN HANCEVILLE HARTSELLS HATBORO HAYESVILLE HAYWOOD HAZLEHURST HECTOR GaSWCC

2.0-6.0 0.06-0.2 0.6-2.0 0.06-0.2 0.6-2.0 0.6-0.2 0.6-2.0 0.6-2.0 0.6-2.0 0.6-2.0 0.6-2.0 0.6-2.0 6.0-2.0 0.06-0.2 2.0-6.0

4.5-5.5

Low

Low

3.6-5.5 4.5-6.0 4.5-5.5

Mod. Low High

High Mod. High

4.5-5.5

Low

Mod.

3.6-5.0

Low

5.1-6.6

Low

4.5-7.3

Low

High High Mod.

4.5-5.5

Mod.

High

3.6-5.5

Low

Mod.

4.5-7.3 4.5-6.0

Low Low

High Mod.

5.1-6.5

Low

Low

4.5-5.5

Low

High

4.5-5.5

Low

Low

Mod.

>6.0

10-20

None

High

+2-1.0

>60

High

>6.0

>60

Mod.

>6.0

>60

None None None

Mod.

>6.0

>60

High

0.5-1.0

>60

Mod.

>6.0

>60

Mod.

2.0-3.0

>60

High

>6.0

>60

None
None Occ Freq
None
None Rare Occ Freq
None

High Mod. Mod.

>6.0 0-0.5 >6.0

20-40 >60 >60

None Occ Freq
None

Mod.

>6.0

>60

High

0.5-2.0

>60

None None

Mod.

>6.0

10-20

None

D

2-15%: S; r

2-7%: S; p, k

2-15%: S; r

2-15%: S; r

15+%: S; r, s

7+%: S; p, r, s

15+%: S; r, s

15+%: S; r, s

D

S; pk, w

S; w

S; w

S; s

0-2%: M; p

B

0-8%: M; pk

2-7%: M; s, p

0-8%: M; cl

8-15%: M; s, pk

7+%: S; s

8-15%: M; s, cl

0-8%: L 8-15%: M; s

C

S; pk

2-7%: M; s

M; cl

7+%: S; s

S; ss

2-8%: L

2-8%: L

B

8-15%: M; s

2-7%: M; s, p

8-15%: M; s

15+%: S; s

7+%: S; s

15+%: S; s

2-8%: L 8-15%: M; s 15+%: S; s

D

None, Rare: S; w, pk

L

Occ, Freq: S; w, pk

S; w

None: S; w Rare,

Occ, Freq: S; f, w

2-8%: M; pk

2-8%: M: cl

2-8%: L

B

8-15%: M; s, pk

2-7%: M; s, p

8-15%: M; cl, s

8-15%: M; s

15+%: S; s

7+%: S; s

15+%: S; s

15+%: S; s

None: M; w#

C

None, Rare: S; w None, Rare: S; w None, Rare: M; w

Rare, Occ, Freq: S; f# None: S; w*

Occ, Freq: S; f, w

Occ, Freq: S; f, w Occ, Freq: M; w, f

Rare, Occ, Freq: S; f, w*

0-8%: M; pk

0-2%: M; p

0-8%: M; cl

0-8%: M; ss

B

8-15%: M; pk, s

2-7%: M; p, s

8-15%: M; cl, s

8-15%: M; ss, s

15+%: S; s

7+%: S; s

15+%: S; s

15+%: S; s

B

2-15%: S; r

2-7%: S; r

2-15%: S; r

2-15%: M; r, s#

15+%: S; r, s

7+%: S; r, s

15+%: S; r, s

15+%: S; s S; r

D

S; f, w

S; f, w, p

S; w

S; f, w

2-8%: M; pk

2-8%: M; cl

B

8-15%: M; pk, s

2-7%: M; s, p

8-15%: M; cl, s

15+%: S; s

7+%: S; s

15+%: S; s

2-8%: S; pf

2-8%: L

B

8-15%: M; s, pf

2-7%: S; p

8-15%: M; s

15+%: S; s, pf

7+%: S; s, p

15+%: S; s

C

S; w, pk

0-2%: L

S; w

2-3%: M; s

D

2-15%: S; r

2-7%: S; r, p

2-15%: S; r

15+%: S; s, r

7+%: S; s, r, p

15+%: S; s, r

2-8%: L 8-15%: M; s 15+%: S; s
2-8%: L 8-15%: M; s 15+%: S; s
S; w
2-15%: S; r 2-8%: S; r* 15+%: S; r

2-8%: S; r 8+%: S; r, s
S; w
0-4%: L 4-8%: M; s 8-15%: S; s
2-8%: S; ss 8+%: S; ss, s
2-4%: L 4-8%: M; s 8+%: S; s
None: S; w Rare, Occ, Freq: S; f, w
2-4%: L 4-8%: M; s 8+%: S; s
None: M; w Rare, Occ, Freq: S; r
0-4%: M; ss 4-8%: M; ss, s
8+%: S; s 2-4%: M; r 4-8%: M; s, r 8+%: S; s
S; f, w
2-4%: L 4-8%: M; s 8+%: S; s
2-4%: L 4-8%: M; s 15+%: S; s
S; w

2-15%: s, r 15+%: S; r, s
S; w
0-8%: L 8-15%: M; s
S; ss, b
2-8%: M; b 8-15%: M; s, b
15+%: S; s
None, Rare: S; b, w Occ, Freq: S; b, w, f
2-8%: M; b 8-15%: M; s, b
15+%: S; s
None, Rare: M; b, w Occ, Freq: S; f
0-15%: S; b 15+%: S; b, s
2-8%: M; r 8-15%: M; s, r
15+%: S; s
S; f, w
2-8%: M; b 8-15%: M; b, s 15-25%: S; s
2-8%: L 8-15%: M; s 15+%: S; s
S; w

2-8%: S; r 8+%: S; s, r

2-15%: S; r 15+%: S; s, r
B-1-19

SOIL SERIES INTERPRETATIONS

SOIL SERIES

ESTIMATED SOIL PROPERTIES

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

SEPTIC TANK ABSORPTION
FIELDS

HELENA

0.06-0.2

4.5-5.5

High

High

High

1.5-2.5

>60

None

C

S; pk, w

HENDERSON HERNDON

0.06-0.2 0.6-2.0

4.5-5.5

Low

High

Mod.

>6.0

>60

None

B

2-15%: S; pk

15+%: S; pk, s

3.6-5.5

Low

High

High

>6.0

>60

None

B

2-8%: M; cl

8-15%: M; s, cl

SEWAGE LAGOON AREAS
0-2%: L 2-7%: M; s 7+%: S; s
2-7%: M; s, p 7+%: S; s
2-7%: M; p, s 7+%: S; s

SHALLOW EXCAVATIONS
S; w
2-8%: M; cl 8-15%: M; cl, s
15+%: S; s
2-8%: M; cl 8-15%: M; s, cl

HEROD HIWASSEE HOLSTON HORNSVILLE HULETT IREDELL IRVINGTON IUKA IZAGORA JOHNS JOHNSTON

0.6-2.0 0.6-2.0 0.6-2.0 .02-.06 0.6-2.0 0.06-0.2 0.06-0.2 0.6-2.0 0.06-0.2 0.6-2.0 2.0-6.0

5.1-7.3 4.5-6.5 4.5-5.5

Low Mod. Low

High Mod. Mod.

4.5-6.0

Low

High

4.5-5.5

Low

High

5.5-7.8 4.5-5.5

High Low

High Mod.

4.5-5.5

Low

Mod.

3.6-5.5 4.5-5.5

Mod. Low

Mod. Mod.

4.5-5.5

Low

High

Mod.

0.5-1.5

>60

Mod.

>6.0

>60

High

>6.0

>60

Freq None None

High

2.5-3.5

>60

Mod.

>6.0

>60

None Rare
None

Low

1.0-2.0

>60

Mod.

1.5-3.5

>60

High

1.0-3.0

>60

High

2.0-3.0

>60

High

1.5-3.0

>60

None
None
Rare Occ Freq None Rare Occ None Rare

High

+1-1.5

>60

Freq

D

S; f, w

S; f, w

S; w

2-8%: M; pk

2-8%: M; cl

B

8-15%M; pk, s

0-7%: M; p, s

8-15%: M; s, cl

15+%: S; s

7+%: S; s

15+%: S; s

0-8%: M; pk

0-2%: M; p

0-8%: L

B

8-15%: M; s, pk

2-7%: M; s, p

8-15%: M; s

15+%: S; s

7+%: S; s

15+%: S; s

0-7%: None: S; w

C

S; w, pk

7+%: None: S; w, s

M; cl, w

Rare: S; w

B

2-8%: M; pk

2-7%: M; s, p

2-8%: M: cl

8-15%: M; s, pk

7+%: S; s

8-15%: M; s, cl

D

S; w, pk

0-7%: S; w

S; w

7+%: S; s, w

C

S; w, pk

0-2%: L 2-5%: M; s

Rare: S; w

C

Occ, Freq: S;

w, f

S; f, w

0-7%: None: S; w

C

None, Rare: S; W, pk

7+%: None: S; w, s 0- 7%: Rare, Occ: S; f, w

Occ: S; f, w, pk

7+%: Rare, Occ: S; f, w, s

C

S; w

None: S; w, p

Rare: S; w, f, p

S; w S; w S; w S; w

D

S; f, w

S; f, w, p

S; w

JUNALUSKA KALMIA KERSHAW GaSWCC

0.6-2.0 0.6-2.0
>20

4.5-6.0

Low

Mod.

High

>6.0

20-40

None

B

4.5-5.5

Low

Mod.

Mod.

>6.0

>60

None

B

Rare

4.5-6.0

Low

Low

High

>6.0

>60

None

A

8-15%: S; r 15+%: S; r, s
L
S; pf

S; r, s
None: S; s Rare: S; f, p
2-7%: S; s 7+%: S; s, p

S; f, w
8-15%: M; r, s 15+%: S; s S; cc

LIMITATION OF SOILS FOR URBAN USES

DWELLINGS *w/basement #w/o basement
S; ss# S; ss, w* 2-8%: L 8-15%: M; s 15+%: S; s
2-8%: L 8-15%: M; s
S; f, w
2-8%: L 8-15%: M; s 15+%: S; s
0-8%: L 8-15%: M; s 15+%: S; s
None: L# None: M; w*
Rare: S; f
2-8%: M; cl 8-15%: M; s
S; ss, w
M; w# S; w*

SMALL COMMERCIAL
BUILDINGS
0-8%: S; ss 8+%: S; s, ss
2-4%: L 4-8%: M; s 8+%: S; s
2-4%: L 4-8%: M; s 8+%: S; s
S; f, w
2-4%: L 4-8%: M; s 8+%: S; s
0-4%: L 4-8%: M; s 8+%: S; s
0-4%: None: L 4-8%: None: M; s
Rare: S; f 2-8%: L 4-8%: M; s 8+%: S; s
0-8%: S; w, ss 8+%: S; w, ss, s
M; w

LOCAL ROADS AND
STREETS
S; ss, b
2-15%: S; b 15+%: S; s, b
S; b
S; f, w
2-15%: S; b 15+%: S; s, b
0-8%: L 8-15%: M; s 15+%: S; s
None: M; b Rare: M; b, f
2-8%: M; b 8-15%: S; s, b
S; ss, b
M; w

S; w, f
None: M; w# None: S; w* Rare, Occ: S; f, w None: M; w# None: S; w* Rare: S; w, f
S; f, w
8-15%: M; s# 8-15%: M; s, r*
15+%: S; s
None: L Rare: S; f
2-8%: L 8-15%: M; s

S; w, f
None: M; w Rare, Occ: S; f, w
None: M; w Rare: S; f
S; f, w
S; s
0-4%: None: L 4-6%: None: M; s
Rare: S; f 2-4%: L 4-8%: M; s 8+%: S; s

Rare: M; w, f Occ, Freq: S; f
None, Rare: S; b Occ: S; b, f
None: M; w Rare: M; w, f
S; f, w
8-15%: M; b, s 15+%: S; s
None: L Rare: M; f
2-8%: L 8-15%: M; s
B-1-21

SOIL SERIES INTERPRETATIONS

SOIL SERIES KINGSLAND

ESTIMATED SOIL PROPERTIES

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

6.0-20

Occ

4.5-6.5

Low

Mod.

Mod.

0-0.5

>60

Freq

A/D

SEPTIC TANK ABSORPTION
FIELDS
S; f, w

SEWAGE LAGOON AREAS
S; f, p, h

LIMITATION OF SOILS FOR URBAN USES

SHALLOW EXCAVATIONS

DWELLINGS *w/basement #w/o basement

S; w, h

S; f, w

SMALL COMMERCIAL
BUILDINGS
S; f, w

LOCAL ROADS AND
STREETS
S; f, w

KINSTON KOLOMOKI KUREB LAKELAND LEADVALE LEAF LEEFIELD

0.6-2.0 0.6-2.0 6.0-20 6.0-20 0.06-0.6 0.06-0.2 0.2-0.6

4.5-5.5 4.5-6.0

Low Low

4.5-7.3

Low

4.5-6.0

Low

4.5-5.5

Low

3.6-5.5

High

4.5-5.5

Low.

High Mod. Low Low Mod. High Mod.

High

0-1.0

>60

Mod.

>6.0

>60

Low

>6.0

>60

Mod.

>6.0

>60

Mod.

2.0-3.0

>48

Mod.

0.5-1.5

>60

High

1.5-2.5

>60

Occ Freq
None Rare
None
None
None Rare
None Rare Occ Freq
None

B/D

S; f, w

S; f, w

B

None: L

None: S; p

Rare: M; f

Rare: S; p, f

A

0-15%: S; pf

0-15%: S; p

15+%: S; p, f, s

15+%: S; p, s

0-8%: L s

A

8-15%: M;

0-7%: S; p

15+%: S; s

7+%: S; s, p

0-7%: None: S; w

C

S; w, pk

7+%: None: S; s, w 0-7%: Rare: S; f, w

7+%: Rare: S; f, w, s

D

None, Rare: S; w, pk None, Rare: L

Occ, Freq: S; f, w, pk Occ, Freq: S; f

C

S;w,pk

M;w,p

S; f, w
S; cc
0-15%: S; cc 15+%: S; s, cc 0-15%: S; cc 15+%: S; s, cc
S; w
S; w
S;w

S; w
None: L Rare: S; f
0-8%: L 8-15%: M; s 15+%: S; s
0-8%: L 8-15%: M; s 15+%: S: s None: M; w# None: S; w*
Rare: S; f None: S; w, ss Rare, Occ, Freq: S; f,
w, ss
M;w# S;w*

S; f, w
0-4%: L 4-8%: M; s 8+%: S; f
0-4%: L 4-8%: M; s 8+%: S; s
0-4%: L 4-8%: M; s 8+%: S; s 0.8%: None: M; w 8+%: None: S; s Rare: S; f None: S; w, ss Rare, Occ, Freq: S; f,
w, ss
M;w

S; f, w, b
None: M; b Rare: M; b, f
0-8%: L 8-15%: M; s 15+%: S; s
0-8%: L 8-15%: M; s 15+%: S; s
0-8%: M; b, w 8-15%: M; sw, b
S; w, ss, b
M;w

LEESBURG

0.6-2.0

2-8%: M; pk

2-8%: L

4.5-5.5

Mod.

Low

Mod.

>6.0

>60

None

B

8-15%: M; pKs

2-7%: M; p, s

8-15%: M; s

15+%: S; s

7+%: S; s

15+%: S; s

2-8%: L 8-15%: M; s 15+%: S; s

2-4%: L 4-8%: M; s 8+%: S; s

2-8%: L 8-15%: M; s 15+%: S; s

LEON

0.6-6.0

3.6-5.5

Low

High

High

0-1.0

>60

None

B/D

S; w, pf

S; w, p

S; w, cc

S; w

S; w

S; w

LEVY LILY LINKER LOCKHART LOCUST LOUISA LOUISBURG GaSWCC

0.06-0.2 2.0-6.0 0.6-2.0 2.0-6.0 0.06-0.2 2.0-6.0 6.0-20

3.6-5.5

High

High

High

+2-+1

>60

Freq

D

S; f, pk

S; f

S; f

S; f, ss

3.6-5.5

Low

Mod.

High

>6.0

20-40

None

B

0-15%: S; r 15+%: S; r, s

0-7%: S; p, r 7+%: S; p, r, s

0-15%: S; r 15+%: S; r, s

0-15%: M; r, s# 0-15%: S; r*
15+%: S; s#, r*

3.6-5.5

Low

Low

High

>6.0

20-40

None

B

5.1-6.5

Low

Low

Mod.

>6.0

>60

None

B

1-15%: S; r 15+%: S; s, r
2-8%: L 8-15%: M; S 15+%: S; s

1-7%: S; r 7+%: S; s, r
2-7%: S: p 7+%: S; s, p

1-15%: S; r 15+%: S; s, r
2-8%: L 8-15%: M; s 8-15%: M; s

1-8%: M; r# 8-15%: M; r, s#
1-15%: S; r* 15+%: S; s
2-8%: L 8-15%: M; s 15+%: S; s

4.5-5.5

Low

Mod.

High

1.5-2.0

>60

None

C

S; pk, w

0-7%: S; w

S; w

7+%: S; s, w

0-8%: M; w# 8-10%: M; s#
S; w*

4.5-6.0

Low

Low

Mod.

>6.0

>60

None

B

6-8%: L 8-15%: M; s 15+%: S; s

S; p, s

6-8%: L 8-15%: M; s 15+%: S; s

6-8%: L 8-15%: M; s 15+%: S; s

2-8%: M; r

2-8%: M; r

2-8%: M; r*

4.5-6.0

Low

Low

Mod.

>6.0

>40

None

B

8-15%: M; r, s

2-7%: S; p

8-15%: M; r, s

2-8%: L#

15+%: S; s

7+%: S; p, s

15+%: S; s

8-15%: M; s#

S; f, ss
0-4%: M; r 4-8%: M; r, s
8+%: S; s
1-4%: S; r 4-8%: M; r, s
8+%: S; s 2-4%: L 4-8%: M; s 8+%: S; s
0-4%: M; w 4-8%: M; s, w
8+%: S; s
6-8%: M; s 8+%: S; s 2-4%: L 4-8%: M; s 8+%: S; s

S; f, f
0-8%: M; r 8-15%: M; r, s
15+%: S; s 1-8%: M; r 8-15%: M; r, s 15+%: S; s 2-8%: L 8-15%: M; s 15+%: S; s
0-8%: M; w 8-10%: M; s, w
6-8%: L 8-15%: M; s 15+%: S; s
2-8%: L 8-15%: M; s 15+%: S; s
B-1-23

SOIL SERIES INTERPRETATIONS

SOIL SERIES LOWNDES LUCY LUMBEE

ESTIMATED SOIL PROPERTIES

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

0.6-2.0

4.5-6.0

Low

Mod.

High

>6.0

>60

None

B

0.6-2.0 0.6-2.0

4.5-5.5

Low

4.5-5.5

Low

Low High

High

>6.0

>60

None

A

Rare

High

0-1.5

>60

Occ

B/D

Freq

SEPTIC TANK ABSORPTION
FIELDS
5-8%: M; pk 8-15%: M; s, pk
15+%: S; s 0-8%: L
8-15%: M; s 15+%: S; s
Rare: S; w Occ, Freq: S; w, f

SEWAGE LAGOON AREAS

SHALLOW EXCAVATIONS

5-7%: S; p 7+%: S; s, p
0-7%: S; p 7+%: S; p, s

5-15%: S; cc 15+%: S; s, cc
0-8%: M; cc 8-15%: M; s, cc
15+%: S; s

Rare: S; p, w Occ, Freq: S; p, w, f

S; w, cc

LYERLY

<0.06

4.5-7.3

High

High

Mod.

>6.0

20-40

None

D

S; pk, r

1-7%: S; r

S; r

7+%: S; s, r

LYNCHBURG

0.6-2.0

3.6-5.5

Low

High

High

0.5-1.5

>60

None

C

S; w

S; w

S; w

LIMITATION OF SOILS FOR URBAN USES

DWELLINGS *w/basement #w/o basement
15+%: S; s 5-8%: L
8-15%: M; s 15+%: S; s
0-8%: L 8-15%: M; s 15+%: S; s
S; w, f
S; ss S; r, ss
S; w

SMALL COMMERCIAL
BUILDINGS
5-8%: M; s 8+%: S; s 0-4%: L 4-8%: M; s 8+%: S; s
S; w, f
1-8%: S; ss 8+%: S; s, ss
S; w

LOCAL ROADS AND
STREETS
5-8%: L 8-15%: M; s 15+%: S; s
0-8%: L 8-15%: M; s 15+%: S; s
Rare: S; w Occ, Freq: S; w, f
S; ss, b
S; w

LYNN HAVEN MADISON MANDARIN MARLBORO MASADA MASCOTTE MAXTON MECKLENBURG MEGGETT MINVALE MOLENA MONTEVALLO GaSWCC

0.6-6.0 0.6-2.0 0.6-2.0 0.6-2.0 0.6-2.0 0.6-2.0 0.6-2.0 0.06-0.2 0.06-0.2 0.6-2.0 6.0-2.0 0.6-2.0

3.6-5.5 4.5-6.0 3.6-7.3 4.5-6.0 4.5-5.5 3.6-5.5 4.5-5.5 5.6-7.3 5.1-8.4 4.5-5.5 4.5-6.0 4.5-6.0

Low Low Low Low Mod. Low Low Mod. High Low Low Low

High High Mod. High Mod. High Mod. High High Mod. Low Mod.

High

0-1.0

>60

None

Mod.

>6.0

>60

None

High

1.5-3.5

>60

None

High

>6.0

>60

None

High

>6.0

>60

None

High

0-1.0

>60

None

Mod.

>6.0

None

>60

Rare

Mod.

>6.0

>48

None

Mod.

0-1.0

>60

None Rare Occ Freq

Low

>6.0

>60

None

High

>6.0

None

>60

Rare

Mod.

>6.0

10-20

None

B/D

S; w, pf

2-8%: M; pk

B

8-15%: M; pk, s

15+%: S; s

C

S; w, pf

B

0-8%: M; pk

8-15%: M; pk, s

0-8%: M; pk

C

8-15%: M; pk, s

15+%: S; s

B/D

S; w, pf

S; p, w
2-7%: M; p 7+%: S; s
S; pw
0-2%: M; p 2-7%: M; s, p
7+%: S; s 0-2%: M; p 2-7%: M; p, s 7+%: S; s
S; w, p

S; cc, w
2-8%: M; cl 8-15%: M; cl, s
15+%: S; s
S; cc, w
0-8%: M; cl 8-15%: M; cl, s
0-8%: M; cl 8-15%: M; cl, s
15+%: S; s
S; w, cc

S; w
2-8%: L 8-15%: M; s 15+%: S; s
M; w# S; w*
0-8%: L 8-15%: M; s 0-8%: M; ss 8-15%: M; ss, s 15+%: S; s
S; w

B

L

S; p

S; cc

None: L

Rare: S; f

2-8%: M; cl

2-8%: S; ss

C

2-15%: S; pk

2-7%: M; s, r, p

8-15%: M; cl, s

8-15%: M; ss, s

15+%: S; s, pk

7+%: S; s

15+%: S; s

15+%: S; s

D

None, Rare: S; pk, w None, Rare: S; w

S; w

None: S; w, ss

Occ, Freq: S; pk, w, f Occ, Freq: S; w, f

Occ, Freq: S; f, w, ss

2-8%: M; pk

B

8-15%: M; s, pk

2-7%: M; s, p

15+%: S; s

7+%: S; s

2-8%: L 8-15%: S; s 15+%: S; s

A

0-15%: S; pf

0-7%: S; p

0-15%: S; cc

15+%: S; pf, s

7+%: S; s

15+%: S; cc, s

D

2-15%: S; r

2-7%: S; r

2-15%: S; r

15+%: S; s, r

7+%: S; s, r

15+%: S; s, r

2-8%: L 8-15%: M; s 15+%: S; s
0-8%: None: L 8-15%: None: M; s 15+%: None: S; s 0-15%: Rare: S; f 15+%: Rare: S; f, s
2-8%: M; r# 8-15%: S; s, r#
15+%: S; s 2-15%: S; r*

S; w
2-4%: L 4-8%: M; s 8+%: S; s
M; w
0-4%: L 4-8%: M; s 8-15%: S; s 0-4%: M; ss 4-8%: M; s, ss 8+%: S; s
S; w
0-4%: None: L 4-8%: None: M; s
Rare: S; f 2-4%: M; ss 4-8%: M; ss, s 8+%: S; s
None: S; w, ss Occ, Freq: S; f, w, ss
2-4%: L 4-8%: M; s 8+%: S; s
0-4%: L 4-8%: M; s 8-15%: S; s Rare: S; f
2-4%: M; r 4-8%: M; r, s
8+%: S; s

S; w
0-15%: S; b 15+%: S; s: b
M; w
0-8%: M; b 8-15%: M; b, s
0-15%: S; b 15+%: S; b, s
S; w
None: L Rare: M; f
2-15%: S; b 15+%: S; s, b
None: Rare: S; w, ss Occ, Freq: S; f, w, ss
2-8%: M; b 8-15%: M; b, s
15+%: S; s
0-8%: L 8-15%: M; s 15+%: S; s Rare: M; f
2-8%: M; r 8-15%: M; s, r
15+%: S; s B-1-25

SOIL SERIES INTERPRETATIONS

SOIL SERIES

ESTIMATED SOIL PROPERTIES

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

SEPTIC TANK ABSORPTION
FIELDS

SEWAGE LAGOON AREAS

LIMITATION OF SOILS FOR URBAN USES

SHALLOW EXCAVATIONS

DWELLINGS *w/basement #w/o basement

SMALL COMMERCIAL
BUILDINGS

LOCAL ROADS AND
STREETS

MOUNTAINBURG

2.0-6.0

MOUNTAINVIEW

0.6-2.0

4.5-5.5

Low

Low

High

>6.0

12-20

None

D

4.5-5.5

Mod.

Mod.

Mod.

>6.0

>60

None

B

1-15%: S; r 15+%: S; s, r
2-8%: L 8-15%: M; s

1-7%: S; r, p 7+%: S; s, r, p
2-7%: M; s, p 7-15%: S; s

1-15%: S; r 15+%: S; s, r
2-8%: L 8-15%: M; s

1-15%: S; r 15+%: S; r, s
2-8%: L 8-15%: M; s

1-8%: S; r 8+%: S; r, s
2-4%: L 4-8%: M; s 8-15%: S; s

1-15%: S; r 15+%: S; r, s
2-8%: L 8-15%: M; s

MUCKALEE MUSELLA MYATT NANKIN NANTAHALA NASON NAUVOO NELLA NORFOLK OCHLOCKONEE OCILLA OGEECHEE OKTIBBEHA OLUSTEE ORANGEBURG GaSWCC

0.6-2.0 0.6-2.0 0.2-2.0 0.2-0.6 0.6-2.0 0.6-2.0 0.6-2.0 0.6-2.0 0.6-2.0 2.0-6.0 0.6-2.0 0.6-2.0 >0.06 0.6-2.0 0.6-2.0

5.1-8.4 5.1-6.5 3.5-5.5

Low

High

Low

Mod.

Low

High

4.5-5.5 4.5-6.0 4.5-5.5

Low Mod. Mod.

High High Mod.

4.5-6.0

Low

Low

4.5-5.5

Low

Mod.

4.5-5.5

Low

4.5-5.5

Low

Mod. Low

4.5-5.5

Low

High

4.5-6.0

Low

High

4.5-8.4

High

High

4.5-5.5

Mod.

High

4.5-6.0

Low

Mod.

Mod.

0.5-1.5

>60

Freq

Mod. High High

>6.0 0-1.0 >6.0

14-20 >60 >60

None
None Rare Occ Freq
None

Mod.

>6.0

40-60

None

High

>6.0

40-60

None

High

>6.0

40-60

None

Mod.

>6.0

>60

None

High

4.0-6.0

>60

High

3.0-5.0

>60

None
Rare Occ

Mod.

1.0-2.5

>60

High

0-1.0

>60

High

>6.0

>60

None
None Rare Occ Freq
None

High

0-1.0

>60

None

Mod.

>6.0

>60

None

D

S; f, w

B

6-15%: S; r

15+%: S; r, s

S; f, w S; r, s

S; w, cc
6-15%: S; r 15+%: S; r, s

S; f, w
6-15%: M; r# 15+%: S; s# 6-15%: S; r* 15+%:S;r,s*

S; f, w
6-8%: M; s, r 8+%: S; s

D

None, Rare: S; w, pk None, Rare: S; w

Occ, Freq: S; w, f, pk Occ, Freq: S; w, f

S; w

None: S; w

None: S; w

Rare, Occ, Freq, S; w,f Rare, Occ, Freq: S; w,f

0-2%: M; p

0-8%: M; cl

C

0-15%: S; pk

2-7%: M; p, s

8-15%: M; s, cl

15+%: S; pk, s

7+%: S; s

15+%: S; s

0-8%: L 8-15%: M; s 15+%: S; s

2-8%: M; r, pk

2-8%: M; cl

2-8%: M; ss

B

8-15%: M; r, pk, s

2-7%: M; r, s

8-15%: M; cl, s

8-15%: M; ss, s

15+%: S; s

7+%: S; s

15+%: S; s

15+%: S; s

0-8%: M; pk, r

0-2%: M; p, r

0-8%: M; c

0-8%: M: ss

C

8-15%: M; s, r, pk 2-7%: M; pk, r, s

8-15%: S; s, cl

8-15%: M; s, ss

15+%: S; s

7+%: S; s

15+%: S; s

15+%: S; s

0-4%: L 4-8%: M; s 8+%: S; s
2-4%: M; ss 4-8%: M; ss, s
8+%: S; s
0-4%: M; ss 4-8%: M; s, ss
8+%: S; s

2-8%: M; r, pk

2-8%: L

B

8-15%: M; r, pk, s

2-7%: M; p, r, s

8-15%: M; s

15+%: S; s

7+%: S; s

15+%: S; s

2-8%: L 8-15%: M; s 15+%: S; s

2-4%: L 4-8%: M; s 8+%: S; s

2-8%: M; pk

2-8%: L

B

8-15%: M, s, pk

2-7%: M; s, p, st

8-15%: M; s

15+%: S; s

7+%: S; s

15+%: S; s

B

0-8%: M; w

0-7%: M; p

8-10%: M; s, w

7+%: S; s

0-8%: M; w 8+%: M; s, w

2-8%: L 8-15%: M; s 15+%: S; s
0-8%: L# 8-10%: M; s# 0-8%: M; w* 8-10%: M; w, s*

2-4%: L 4-8%: M; s 8+%: S; s
0-4%: L 4-8%: M; s 8+%: S; s

B

Rare: S; w

Occ, Freq: S; w, f

C

S; w

S; f, p, w S; w, p

M; w S; w, cc

S; f
None: M; w# None: S; w* Rare: S; w, f

S; f
None: S; w Rare: S; f, w

B/D

None, Rare: S; w None, Rare: S; w

S; w

Occ, Freq: S; w, f Occ, Freq: S; w, f

None: S; w Rare, Occ, Freq: S; w, f

None: S; w Rare, Occ, Freq: S; w, f

1 -2%: L

1-8%: M; cl

D

1-15%: S; pk

2-7%: M; s

8-15%: M; cl, s

1-15%: S; ss

15+%: S; pk, s

7+%: S; s

15+%: S; s

15+%: S; ss, s

1-8%: S; ss 15+%: S; ss, s

B/D

S; w

S; w, p

S; w, cc

S; w

S; w

0-8%: L

0-2%: M; p

0-8%: L

B

8-15%: M; s

2-7%: M; s, p

8-15%: M; s

15+%: S; s

7+%: S; s

15+%: S; s

0-8%L 8-15%: M; s 15+%: S; s

0-4%: L 4-8%: M; s 8+%: S; s

S; f, w
6-15%: M; r, s 15+%: S; s
None, Rare: S; w Occ, Freq: S; w, f
2-8%: L 8-15%: M; s 15+%: S; s
2-15%: S; b 15+%: S; b, s
0-15%: S; b 15+%:S;s,b 2-8%: M; b 8-15%: M; b, s 15+%: S; s
2-8%: L 8-15%: M; s 15+%: S; s
0-8%: L 8-10%: M; s
Rare: M; f Occ, Freq: S; f
None: M; w Rare: M; w, f
None: Rare: S; w Occ, Freq: S; w, f
1-15%: S; ss, b 15+%: S; ss, b, s
S; w
0-8%: L 8-15%: M; s 15+%: S; s
B-1-27

SOIL SERIES INTERPRETATIONS

SOIL SERIES OSIER OUSLEY

ESTIMATED SOIL PROPERTIES

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

SEPTIC TANK ABSORPTION
FIELDS

SEWAGE LAGOON AREAS

SHALLOW EXCAVATIONS

6.0-2.0 6.0-20

3.6-6.0

Low

4.5-5.5

Low

High Low

High

0-1.0

>60

High

1.5-3.0

>60

None Rare Occ Freq
Occ Freq

A/D None, Rare: S; w, pf None, Rare: S; w, p Occ, Freq: S; w, f, pf Occ, Freq: S; w, f, p

C

S; f, w, pf

S; f, p, w

S; w, cc S; cc, w

LIMITATION OF SOILS FOR URBAN USES

DWELLINGS *w/basement #w/o basement

SMALL COMMERCIAL
BUILDINGS

LOCAL ROADS AND
STREETS

None: S; w Rare, Occ, Freq: S; w, f
S; f# S; f, w*

None: S; w Rare, Occ, Freq: S; w, f
S; f

None: Rare: S; w Occ, Freq: S; w, f
S; f

PACOLET

0.6-2.0

4.5-6.0

Low

High

High

>6.0

>60

None

2-8%: M; pk

2-8%: M; cl

B

8-15%: M; s, pk

2-7%: M; s, p

8-15%: M; s, cl

15+%: S; s

7+%: S; s

15+%: S; s

2-8%: L 8-15%: M; s 15+%: S; s

2-4%: L 4-8%: M; s 8+%: S; s

2-8%: M; b 8-15%: M; s, b
15+%: S; s

PASQUATANK PELHAM PELION PERSANTI

0.6-2.0 0.6-2.0 .06-0.6 0.06-0.2

4.5-5.5

Low

3.6-5.5

Low

3.6-5.5 3.6-5.5

Low Mod.

High High High High

Mod.

1.0-2.0

>60

High

0-1.0

>60

High

1.0-2.5

>60

High

2.0-3.5

>60

None
None Rare Occ Freq
None
None

B/D

S; w

S; w, p

B/D

None, Rare: S; w None, Rare: S; w, p

Occ, Freq: S; w, f Occ, Freq: S; w, f, p

B/D

S; pk, w

C

S; w, pk

0-7%: S; w 7+%: S; s
0-2%: L 2-6%: M; s

S; w S; w, cc
S; w S; w

S; w

S; w

M; w

None: S; w

None: S; w

Rare, Occ, Freq: S; w, f Rare, Occ, Freq: S; w, f

S; w
M; ss, w# S; w*

0-8%: S; w 8+%: S; s, w
0-4%: M; w, ss 4-6%: M; w, ss, s

None: Rare: S; w Occ, Freq: S; f, w
0-8%: M; w 8-15%: M; w, s
M; b, ss, w

PICKNEY PLUMMER POINDEXTER PONZER

6.0-20 0.6-2.0 0.6-2.0 0.06-2.0

POOLER PORTERS PORTSMOUTH POTTSBURG RABUN RAINS GaSWCC

0.06-0.2 2.0-6.0 0.6-2.0 0.6-2.0 0.6-2.0 0.6-2.0

3.6-6.0 3.6-5.5 5.1-7.3 3.6-7.8
3.6-5.5 4.5-6.0 3.6-6.0 3.6-6.0 5.1-6.5 3.6-5.5

Low Low Low Low

High Mod. Mod. High

Mod. Low Low Low Low Low

High Low High High High High

High High Mod. High
High High

+ 1-1.0

>60

0-1.0

>60

>6.0 0-1.0

20-40 >60

0-1.0 >6.0

>60 40-60

None
None Rare Occ Freq
None
None Rare Occ Freq
None
None

High

0-1.0

>60

None

None

High

0-1.0

>60

Rare

Occ

Mod.

>6.0

>60

None

High

0-1.0

>60

None Rare Occ Freq

A/D

S; w, pf

S; w, p

S; w, cc

S; w

S; w

S; w

B/D None, Rare: S; w, pf None, Rare: S; w, p Occ, Freq: S; w, f, pf Occ, Freq: S; w, f, p

S; w, cc

None: S; w

None: S; w

Rare, Occ, Freq: S; w, f Rare, Occ, Freq: S; w, f

2-8%: M; r

2-8%: L#r*

B

2-15%: S; r

2-7%: S; p, r

8-15%: M; r, s

8-15%: M; s# 8-15%: M; s, r*

15+%: S; r, s

7+%: S; p, r, s

15+%: S; s

15+%: S; s

2-4%: L 4-8%: M; s 8+%: S; s

None: Rare: S; w Occ, Freq: S; w, f
2-8%: L 8-15%: M; s 15+%: S; s

D

Rare: S; w, pk

Occ, Freq: S; f, w, pk

S; f, w, h

S; h, w

S; f, w, b

S; w, f, b

Rare: S; w, b Occ, Freq: S; f, w, b

D

S; pk, w

8-15%: M; r, s

B

6-8%: M; r

15+%: S; s

B/D

S; w, pf

L S; s, p S; w, p

S; w
6-8%: M; r 8-15%: M; r, s
15+%: S; s
S; w, cc

S; w
6-8%: L# 8-15%: M; s# 6-15%: M; r, s* 15+%: S; s
None: S; w Rare: S; w, f

S; w
6-8%: M; s 8+%: S; s None: S; w Rare: S; w, f

S; w, b
6-8%: L 8-15%: M; s
S; w

B/D None, Rare: S; w, pf None, Rare: S; w

Occ: S; f, w, pf

Occ: S; p, f, w,

S; w, cc

2-8%: M; pk

2-8%: M; cl

B

8-15%: M; s, pk

2-7%: M; s, p

8-15%: M; cl, s

15+%: S; s

7+%: S; s

15+%: S; s

None: S; w Rare, Occ: S; f, w
2-8%: L 8-15%: M; s 8+%: S; s

None: S; w Rare, Occ: S; f, w
2-4%: L 4-8%: M; s 8+%: S; s

B/D

None, Rare: S; w None, Rare: S; w

Occ.Freq: S; f, w

Occ, Freq: S; w, f

S; w

None: S; w

None: S; w

Rare, Occ, Freq: S; w, f Rare, Occ, Freq: S; w, f

None, Rare: S; w Occ: S; w, f 2-8%: M; b
8-15%: M; s, b 15+%: S; s
None, Rare: S; w Occ, Freq: S; w, f
B-1-29

SOIL SERIES INTERPRETATIONS

SOIL SERIES

ESTIMATED SOIL PROPERTIES

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

SEPTIC TANK ABSORPTION
FIELDS

SEWAGE LAGOON AREAS

LIMITATION OF SOILS FOR URBAN USES

SHALLOW EXCAVATIONS

DWELLINGS *w/basement #w/o basement

SMALL COMMERCIAL
BUILDINGS

LOCAL ROADS AND
STREETS

RAMSEY RED BAY REMBERT RICEBORO RIDGELAND RIGDON RION RIVERVIEW ROANOKE ROBERTSDALE ROME RUTLEDGE SALUDA SAPELO SATILLA SAWYER SCRANTON GaSWCC

6.-20 0.6-2.0 0.06-0.2 0.06-0.2 0.6-6.0 0.6-2.0 0.6-2.0 0.6-2.0 0.06-0.2 0.06-0.2 0.6-2.0 6.0-20 0.6-2.0 0.6-2.0 2.0-6.0 0.06-0.2 6.0-20

4.5-5.5

Low

4.5-5.5

Low

Low Mod.

4.5-5.5 4.5-5.5 3.6-6.5

Low Mod. Low

High High Mod.

4.5-5.5 4.5-6.5 4.5-5.5 3.6-6.5 4.5-5.5 4.5-5.5 3.6-5.5 4.5-5.5 3.6-5.5 4.5-6.0 4.5-5.5 4.5-6.0

Low Low Low Mod. Low Low Low Low Low Mod. High Low

High Mod. Low High High Low High Mod. High High High Low

Mod.

>6.0

10-20

None

Mod.

>6.0

>60

High

0-1.0

>60

High

0.5-1.0

>60

High

1.5-2.5

>60

High

1.5-2.5

>60

High

>6.0

>60

Mod.

3.0-5.0

>60

High

0-1.0

>60

Mod.

1.0-2.5

>60

High

>6.0

>60

High

0-10

>60

None
None Rare
Occ Freq
None Rare
None
None
Occ Freq
None Rare Occ Freq
None
None Rare Occ Occ Freq

High

>6.0

10-20

None

High

0.5-1.5

>60

High

0-1.5

>60

High

2.0-3.0

>60

None
None Rare Occ Freq
None

High

0.5-1.5

>60

None Rare

D

3-15%: S; r,

3-7%: S; p, r

3-15%: S; r

3-15%: S; r

15+%: S; r, s

7+%: S; p, r, s

15+%: S; r, s

15+%: S; r, s

2-7%: M; p

B

0-8%: L

2-7%: M; p, s

0-8%: L

8-15%: M; s

7+%: S; s

8-15%: M; s

0-8%: L 8-15%: M; s

D

S; w, pk

M; p, w

S; w, cc

S; w

3-8%: S; r 8+%: S; r, s
0-4%: L 4-8%: M; s 8+%: S; s
S; w

3-15%: S; r 15+%: S; r, s
0-8%: L 8-15%: M; s
S; w

B/D

S; f, w, pk

S; f, w

S; cc, w

S; f, w

B/D

S; w, pf

None: S; p, w

S; cc, w

Rare: S; p, w, f

C

S; w

S; w

S; cc, w

None: M; w# None: S; w*
Rare: S; f
M; w# S; w*

2-8%: L

2-8%: L

B

8-15%: M; s

0-7%: S; p

2-15%: S; cc

8-15%: M; s

15+%: S; s

7+%: S; p, s

15+%: S; cc, s

15+%: S; s

B

S; f, w

S; f, p, w

S; cc

S; f

S; f, w
None: M; w Rare: S; f
M; w
2-4%: L 4-8%: M; s 8+%: S; s
S; f

S; f, w
None: M; w Rare: M; w, f
M; w
2-8%: L 8-15%: M; s 15+%: S; s
S; f

D

None, Rare: S; w, pk None, Rare: S; w, p

S; w

None: S; w

None: S; w

None, Rare: S; w, b

Occ, Freq: S; w, f, pk Occ, Freq: S; w, f, p

Rare, Occ, Freq: S; w, f Rare, Occ, Freq: S; w, f Occ, Freq: S; w, b, f

C

S; w, pk

L

S; w

S; w

S; w

M; w

None: L

0-2%: Rare: M; p

0-4%: None: L

B

Rare: M; f

2-6%: None, Rare: M; p, s None, Rare: L

None: L

4-6%: None: M; s

Occ: S; f

Occ: S; f

Occ: M; f

Rare, Occ: S; f

Rare, Occ: S; f

None: M; b Occ: S; f

B/D

S; w, f, pf

S; w, f, p

S; w, cc

S; w, f

S; w, f

S; w, f

C

10-15%: S; r

15+%: S; s, r

D

S; w, pf

S; s, r S; w, p

10-15%: S; r 15+%: S; s, r
S; w, cc

10-15%: M; s, r# 15+%: S; s# 10-15%: S; r* 15+%: S; r, s*
S; w

S; s

10-15%: M; s, r

15+%: S; s

S; w

S; w

D

None, Rare: S; w None, Rare: S; p, h, w

Occ, Freq; S; f, w Occ, Freq: S; p, f, h

C

S; pk, w

1-7%: S; w

7+%: S; w, s

A/D

S; w, pf

S; p, w

S; h, w S; w
S; cc, w

None: S; w, b Rare,

None: S; w, b

Occ, Freq: S; f, w, b Rare, Occ, Freq: S; f,.w, b

M; w, ss# S; ss, w*

1-4%: M; w, ss 4-8%: M; w, ss, s

None: S; w Rare: S; f, w

None: S; w Rare: S; f, w

None, Rare: S; w Occ, Freq: S; f, w
S; b
S; w B-1-31

SOIL SERIES INTERPRETATIONS

SOIL SERIES SEQUATCHIE SHACK SHELLBLUFF

ESTIMATED SOIL PROPERTIES

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

0.6-2.0

None

Rare

4.5-5.5

Low

Low

Mod.

>6.0

>60

Occ

B

Freq

SEPTIC TANK ABSORPTION
FIELDS
None: L Rare:M;f Occ, Freq: S; f

SEWAGE LAGOON AREAS

SHALLOW EXCAVATIONS

0-7%: None: M; p 7+%: None: S; s 0-7%: Rare, Occ, Freq: S; f 7%: Rare, Occ, Freq: S; s, f

0-8%: None, Rare: L 8-12%: None, Rare: M; s
0-8%: Occ, Freq: M; f 8-12%: Occ: Freq: M; s

0.2-0.6 0.6-2.0

4.5-5.5

Low

4.5-6.5

Low

Mod. Mod.

High

2.0-4.0

>60

Mod.

3.0-5.0

>60

None
Occ Freq

B

2-15%: S; w, pk

2-7%: S; w

15+%: S; w, pk, s

7+%: S; s, w

B

S; f, w

S; f, w

2-15%: M; w 15+%: S; s
M; w, f

LIMITATION OF SOILS FOR URBAN USES

DWELLINGS *w/basement #w/o basement
0-8%: None: L 8-12%: None: M; s
Occ, Freq: S; f
2-15%: M; w, s# 15+%: S; s# S; w#
S; f

SMALL COMMERCIAL
BUILDINGS
0-4%: None: L 4-8%: None: M; s 8+%: None: S; s Rare, Occ, Freq: S, f
2-4%: M; w 4-8%: M; s 8+%: S; s
S; f

LOCAL ROADS AND
STREETS
None: L Rare:M;f Occ, Freq: S; f 2-8%: L 8-15%: M; b, s 15+%: S; s
S; f, b

SOCO

8-15%: M; s#

2.0-6.0

3.6-5.5

Low

Mod.

High

>6.0

20-40

None

B

8-15%: S; r

S; p, r, s

8-15%: M; r, s

8-15%: M; r, s*

S; s

15+%: S; r, s

15+%: S; s

15+%: S; s

8-15%: M; s 15+%: S; s

STARR STASER STATE STEEKEE STILSON SUBLIGNA SUCHES SUFFOLK SULLIVAN SUMTER SUNLIGHT SUNSWEET SURRENCY

0.6-2.0 0.6-6.0 0.6-2.0 2.0-6.0 0.6-2.0 6.0-20 0.6-2.0 0.6-2.0 0.6-2.0 0.6-2.0 0.6-2.0 0.2-0.6 0.6-2.0

5.1-6.5 5.6-7.3

Mod. Low

Mod. Low

4.5-6.5

Low

Mod.

4.5-5.5 4.5-5.5

Low Low

Low Mod.

4.5-5.5

Low

Low

4.5-6.0

Low

3.6-6.0

Low

High Mod.

5.1-7.3

Low

7.4-8.4

High

Low Mod.

4.5-5.5

Low

Low

4.5-5.5

Low

3.6-5.5

Low

Mod. High

Mod.

>6.0

>60

Low

3.0-4.0

>60

High

4.0-6.0

>60

Mod.

>6.0

20-40

Rare Occ Rare Occ
None Rare Occ
None

High

2.5-3.0

>60

High

>6.0

>60

Mod.

2.5-4.0

>60

High

>6.0

>60

Low

4.0-6.0

>60

None
Rare Occ
Occ Freq
None
Occ Freq

Low

>6.0

20-40

None

High

>6.0

10-20

None

Mod.

>6.0

>60

None

Occ

High

0-0.5

>60

Freq

C

Rare: M; f

S; f

Rare: L

Occ: S; f

Occ: M; f

B

Rare: S; w

Occ: S; w, f

S; f, w, p

Rare: M; w Occ: M; w, f

None: M; w, pk

B

Rare: M; f, w, pk

None, Rare: S; p

Occ: S; f

Occ: S; p, f

S; cc

C

10-15%: S; r

15+%: S; r, s

S; r, s, p

10-15%: S; r 15+%: S; r, s

B

S; w

S; w

S; cc

S; f
S; f
None: L# None: M; w* Rare, Occ: S; f
10-15%: M; s, r# 15+%: S; s# 10-15%: S; r 15+%: S; r, s
L# M; w*

B

Rare: S; pf

S; p, f

Rare: L

S; f

Occ: S; f, pf

Occ: M; f

B

S; w, f

S; w, f

M; w, f

S; f

0-8%: L

0-8%: L

B

8-15%: M; s

0-7%: S; p

0-15%: S; cc

8-15%: M; S;

15+%: S; s

7+%: S; p, s

15+%: S; cc, s

15+%: S; s

B

S; f

S; f

M; f, w

S; f

1-15%: M; r, cl

C

1-15%: S; r, pk

1-7%: S; r

8-15%: M; r, cl, s

1-15%: S; ss

15+%: S; r, pk, s

7+%: S; r, s

15+%: S; s

15+%: S; ss, s

D

8-15%: S; r

15+%: S; r, s

S; p, r, s

8-15%: S; r 15+%: S; r, s

8-15%: M; s, r# 15+%: S; s# 8-15%: S; r* 15+%: S; r, s

2-8%: M; cl

2-8%: L

C

2-15%: S; pk

2-7%: M; s

8-15%: M; cl, s

8-15%: M; s

15+%: S; pk, s

7+%: S; s

15+%: S; s

15+%: S; s

D

S; w, f

S; w, f, p

S; w, cc

S; w, f

S; f
S; f
0-4%: None: L 4-6%: None: M; s
Rare, Occ: S; f
S; s
0-4%: L 4-8%: M; s
S; f
S; f 0-4%: L 4-8%: M; 3 8+%: S; s
S; f
1-8%: S; ss 8+%: S; ss, s
S; s
2-4%: L 4-8%: M; s 8+%: S; s
S; w, f

Rare: M; ss, b, f Occ: S; f
Rare: M; f Occ: S; f None: M; b Rare: M; b, f Occ: S; f
10-15%: M; r, s 15+%: S; s
L
Rare: M; f Occ: S; f
S; f
0-8%: L 8-15%: M; s
15+%s; s
S; f
1-15%: S; ss, b 15+%: S; ss, b, s
8-15%: M; r, s 15+%: S; s 2-8%: M; b
8-15%: M; s, b 15+%: S; s
S; w, f

GaSWCC

B-1-33

SOIL SERIES INTERPRETATIONS

SOIL SERIES

ESTIMATED SOIL PROPERTIES

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

SEPTIC TANK ABSORPTION
FIELDS

SUSQUEHANNA SWAFFORD

<0.06 0.2-0.6

4.5-5.5

High

High

High

>6.0

>60

None

D

1-15%: S; pk

15+%: S; pk, s

None

4.5-5.5

Low

Mod.

Mod.

2.0-3.0

>60

Rare

C

S; w, pk

SWEETAPPLE

0.2-0.6

4.0-5.5

Low

Mod.

Mod.

>6.0

>60

None

C

2-15%: S; pk

15+%: S; pk, s

LIMITATION OF SOILS FOR URBAN USES

SEWAGE LAGOON AREAS
1-2%: L 2-7%: M; s 7+%: S; s
S; w
2-7%: M; s 7+%: S; s

SHALLOW EXCAVATIONS
1-8%: M; cl 8-15%: M; cl, s
15+%: S; s
S; w
2-8%: M; cl 8-15%: M; cl, s
15+%: S; s

DWELLINGS *w/basement #w/o basement
1-15%: S; ss 15+%: S; ss, s
None: M; w # None: S; w* Rare: S; f* Rare: S; f, w*
2-8%: L 8-15%: M; s 15+%: S; s

SMALL COMMERCIAL
BUILDINGS
1-8%: S; ss 8+%: S; ss, s
0-4%: None: M; w 4-5%: None: M; w, s
Rare: S; f 2-4%: L 4-8%: M; s 8+%: S; s

LOCAL ROADS AND
STREETS
1-15%: S; b, ss 15+%: S; b, ss, s
None: M; w, b Rare: M; w, b, f
2-8%: M; b 8-15%: M; b, s
15+%: S; s

TAFT TALBOTT TALLADEGA TALLAPOOSA TANYARD TATE TATUM TAWCAW THURMONT TIDINGS TIFTON TOCCOA TOWNLEY TOXAWAY GaSWCC

0.06-0.2 0.2-0.6 0.6-2.0 0.6-2.0 0.2-2.0 0.6-2.0 0.6-2.0 0.06-0.2 0.6-2.0 0.6-2.0 0.2-0.6 2.0-6.0 0.06-0.2 0.6-2.0

4.0-5.5 5.1-7.8

High Mod.

High High

4.5-5.5

Low

Mod.

4.5-5.0

Low

Low

4.5-7.8

Low

Mod.

5.1-6.0 4.5-5.5

Low Mod.

Mod. High

4.5-6.5

Mod.

High

4.5-5.5

Low

4.5-5.5

Low

Mod. Low

4.5-5.5

Low

Low

5.1-6.5

Low

Low

3.6-5.5

Mod.

Mod.

5.1-6.0

Low

High

High Mod.

1.0-2.0

>60

>6.0

20-40

None None

High

>6.0

20-40

None

High Mod.

>6.0

10-20

1.5-2.5

>60

None
Occ Freq

Mod.

>6.0

>60

None

High

>6.0

40-60

None

Occ

High

1.5-2.5

>60

Freq

High

4.0-6.0

>60

None

High

>6.0

40-60

None

Mod. Mod. High

3.5-6.0

>60

2.5-5.0

>60

>6.0

20-40

None
None Rare Occ Freq
None

Mod.

0-1.0

>60

Freq

C

S; p, w

S; w

C

0-15%: S; pk, r

0-7%: S; r

15+%: S; s, pk, r

7+%: S; s, r

C

6-15%: S; r

15+%: S; r, s

S; r, s

C

5-15%: S; r

5-7%: S; r

15+%: S; s, r

7+%: S; s, r

S; w

S; w

0-15%: S; r 15+%: S; s, r
6-8%: M: r 8-15%: M; r, s
15+%: S; s
8-15%: S; r 15+%: S; s, r

0-15%: M; ss, r, s# 15+%: S; s# S; r
6-15%: M; r# 6-15%: M; r, s*
15+%: S; s
5-15%: M; r, s# 15+%: S; s# S; r*

S; w
0-4%: M; ss, r 4-8%: M; s, ss, r
8+%: S; s
6-8%: M; s 8+%: S; s
5-8%: M; r, s 8+%: S; s

C

S; f, w, pk

S; f, w

S; w

S; f

S; f

2-8%: L

2-8%: L

B

8-15%: M; s

2-7%: S; p

8-15%: M; s

15+%: S; s

7+%: S; s, p

15+%: S; s

2-8%: L 8-15%: M; s 15+%: S; s

0-8%: M; pk, r

0-2%: M; p, r

0-8%: M; cl

0-8%: M; ss

B

8-15%: M; s, r, pk

2-7%: M; p, s, r

3-15%: M; s, cl

8-15%: M; s, ss

15+%: S; s

7+%: S; s

15+%: S; s

15+%: S; ss

2-4%: L 4-8%: M: s 8+%: S; s
0-4%: M; ss 4-8%: M; s.ss
8+%: S; s

C

S; f, w, pk

S; f, w

S; w

S; f

S; f

2-8%: M; w, pk

2-8%: M; w

B

8-15%: M; w, pk, s 2-7%: M; p, s, w

8-15%: M; w, s

15+%: S; s

7+%: S; s

15+%: S; s

2-8%: L# 2-8%: M; w* 8-15%: M; s 15+%: S; s

2-8%: M; r, pk

2-8%: M; r

2-8%: L#M; r, s*

B

8-15%: M; r, pk, s

2-7%: M; r, p, s

8-15%: M; r, s

2-15%: M; s#, r*

15+%: S; s

7+%: S; s

15+%: S; s

15+%: S; s

0-2%: M; p

B

M; pk, w

2-7%: M; s, p

M; w

L#

7+%: S; s

2-4%: L 4-8%: M; s 8+%: S; s
2-4%: L 4-8%: M; s 8+%: S; s
0-4%: L 4-8%: M; s

B

None, Rare: S; w None, Rare: S; w, p None, Rare: M; w

None: M; w

None: M; w

Occ, Freq: S; w, f Occ, Freq: S; w, f, p Occ: Freq.: M; w, f Rare, Occ, Freq: S; f

Rare, Occ, Freq: S; f

2-8%: M; r, cl

2-8%: M; r, ss*ss#

C

2-15%: S; r

2-7%: S; r

8-15%: M; s, r, cl

8-15%: M; s, r, ss*

15+%: S; s, r

7+%: S; s, r

15+%: S; s

8-15%: M: ss, s# 15+%: S; s

2-4%: M; ss 4-8%: M; s, ss
8+%: S; s

B

S; w, f

S; w, f, p

S; w

S; w, f

S; w, f

S; b
0-15%: S; b 15+%: S; s, b
6-8%: L 8-15%: M; r 15+%: S; s 5-8%: M; r 8-15%: M; s, r 15+%: S: s
S; f, b
2-8%: L 8-15%: M; s 15+%: S; s
0-15%: S; b 15+%: S; b, s
S; f, b
2-8%: L 8-15%: M; s 15+%: S; s 2-8%: M; b 8-15%: M; s, b 15+%: S; s
L
None: M; w Rare: M; w, f Occ, Freq: S; f
2-15%: M; b 15+%: S; s, b
S; w, f, b
B-1-35

SOIL SERIES INTERPRETATIONS

SOIL SERIES

ESTIMATED SOIL PROPERTIES

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

SEPTIC TANK ABSORPTION
FIELDS

SEWAGE LAGOON AREAS

LIMITATION OF SOILS FOR URBAN USES

SHALLOW EXCAVATIONS

DWELLINGS *w/basement #w/o basement

SMALL COMMERCIAL
BUILDINGS

LOCAL ROADS AND
STREETS

TRANSYLVANIA TROUP TSALI TUPELO TUSQUITTEE VALDOSTA VANCE VARINA VAUCLUSE WAGRAM WAHEE WATAUGA WAX WAYNESBORO WEDOWEE WEHADKEE

0.6-2.0 0.6-2.0 0.6-2.0 0.06-0.2 0.6-2.0 6.0-2.0 0.06-0.2 0.06-0.2 0.06-0.6 0.6-2.0 0.06-0.2 0.6-2.0 0.06-2.0 0.6-2.0 0.6-2.0 0.6-2.0

4.5-6.0

Low

High

4.5-5.5

Low

Low

4.0-6.0

Low

Mod.

4.5-8.4 4.5-6.0

High Low

High Mod.

4.5-6.0

Low

Mod.

4.5-5.5 4.5-5.5 3.6-5.5

Mod. Low Low

High Mod. Low

4.5-6.0

Low

Low

3.6-5.5 4.5-6.0

Mod. Low

High Mod.

4.5-5.5

Low

Mod.

4.5-5.5 4.5-5.5 4.5-6.5

Mod. Mod. Low

High Mod. High

High

2.5-3.5

>60

Freq

Mod.

>6.0

>60

None

High Mod. Mod.

>6.0

10-20

1.0-2.0

40-70

>6.0

>60

None
None Rare Occ Freq
None

High

>6.0

>60

None

High

>6.0

>60

None

High

4.0-5.0

>60

None

High

>6.0

>60

None

High

>6.0

>60

High

0.5-1.5

>60

Mod.

>6.0

>60

Mod.

1.5-3.0

>60

None
None Rare Occ Freq
None
Occ Freq

High

>8.0

>60

None

High

>6.0

>60

None

Occ

Mod.

0-0.5

>60

Freq

B

S; f, w

S; f, w

S; f, w

S; f

S; f

S; f, b

0-8%: L

0-8%: L

A

8-15%: M; s

0-7%: S; p

0-15%: S; cc

8-15%: M; s

15+%: S; s

7+%: S; s, p

15+%: S; cc, s

15+%: S; s

C

8-15%: S; r

15+%: S; r, s

S; r, s

8-15%: S; r 15+%: S; r, s

8-15%: M; r, s# 15+%: S; s# 8-15%: S; r* 15+%: S; r, s*

0-4%: L 4-8%: M; s 8+%: S; s
S; s

0-8%: L 8-15%: M; s 15+%: S; s
8-15%: M; r, b, s 15+%: S; s

D

None, Rare: S; w, pk None, Rare: S; w

Occ, Freq: S; w, pk, s Occ, Freq: S; f, w

2-8%: L

B

8-15%: M; s

2-7%: S; p

15+%: S; s

7+%: S; s, p

S; w
2-8%: L 8-15%: M; s 15+%: S; s

None: S; ss, w

None: S; ss, w

Rare, Occ, Freq: S; f, w, ss Rare, Occ, Freq: S; f, w, ss

2-8%: L 8-15%: M; s 15+%: S; s

2-4%: L 8-15%: M; s 8+%: S; s

None, Rare: S; ss, b Occ, Freq: S; ss, b, f
2-8%: L 8-15%: M; s 15+%: S; s

A

S; pf

S; p

S; cc

L

L

L

2-8%: M; cl

2-8%: M: ss

C

2-15%: S; pk

2-7%: M; s

8-15%: M: cl, s

8-15%: M; ss, s

15+%: S; pk, s

7+%: S; s

15+%: S; s

15+%: S; s

C

S; pk

0-2%: L 2-7%: M; s 7+%: S; s

2-8%: M; cl, w 8-10%: M; s, cl, w

0-8%: L# 8-10%: M; s# 0-8%: M; w* 8-10%: M; w, s*

2-15%: S; cc

2-8%: L

C

2-15%: S; pk

2-7%: S; p

2-8%: S; cc

8-15%: M; s

15+%: S; pk, s

7+%: S; s, p

15+%: S; s, cc

15+%: S; s

2-4%: M; ss 4-8%: M; ss, s
8+%: S; s
0-4%: L 4-8%: M; s 8+%: S; s
2-4%: L 4-8%: M; s 8+%: S; s

2-15%: S; b 15+%: S; b, s
0-8%: M; b 8-10%: M; s, b
2-8%: L 8-15%: M; s 15+%: S; s

A

0-8%: L

0-7%: S; p

0-8%: L

0-8%: L

8-15%: M; s

7+%: S; s

8-15%: M; S;

8-15%: M; s

0-4%: L 4-8%: M; s 8+%: S; s

0-8%: L 8-15%: M; s

0-2%: None, Rare: L

D

None, Rare: S; w, pk 2-4%: None, Rare: M; s

S; w

Occ, Freq: S; w, f, pk Occ, Freq: S; f

None: S; w

None: S; w

Rare, Occ, Freq: S; w, f Rare, Occ, Freq: S; w, f

None, Rare: S; b, w Occ, Freq: S; f, b, w

5-8%: L

5-8%: L

B

8-15%: M; s

6-7%: M; r, s, p

8-15%: M; s

15+%: S; s

7+%: S; s

15+%: S; s

5-8%: S; 8-15%: M; s 15+%: S; s

5-8%: M; s 8+%: S; s

5-15%: S; b 15+%: S; s, b

C

S; pk, f

S; w, f

S; w

S; f, w

S; f

S; f

2-8%: M; pk

2-8%: M; cl

2-8%: M; ss

B

8-15%: M; s, pk

2-7%: M; s, p

8-15%: M; s.cl

8-15%: M; s, ss

15+%: S; s

7+%: S; s

15+%: S; s

15+%: S; s

0-2%: M; pk

0-2%: M; b

0-8%: M; cl

0-8%: M; ss

B

8-15%: M; s, pk

2-7%: M; s, p

8-15%: M; s, cl

8-15%: M; s, ss

15+%: S; s

7+%: S; s

15+%: S; s

8+%: S; s

2-4%: M; ss 4-8%: M; s, ss
8+%: S; s
0-4%: M; ss 4-8%: M; s, ss
8+%: S; s

2-8%: M; b, ss 8-15%: M; s, b, ss
15+%: S; s
0-8%: M; b, ss 8-15%: M; s, b, ss
8+%: S, s

D

S; f, w

S; f, w

S; w

S; f, w

S; f, w

S; f, w

WESTON

0.06-6.0

4.5.5.0

Low

High

High

0-1.0

>60

None

D

S; w, pk

S; p, w

S; cc, w

S; w

S; w

S; w

GaSWCC

B-1-37

SOIL SERIES INTERPRETATIONS

SOIL SERIES WHITWELL WICKHAM WICKSBURG WILKES WOLFTEVER WORSHAM ZION

ESTIMATED SOIL PROPERTIES

LIMITATION OF SOILS FOR URBAN USES

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

SEPTIC TANK ABSORPTION
FIELDS

SEWAGE LAGOON AREAS

SHALLOW EXCAVATIONS

DWELLINGS *w/basement #w/o basement

SMALL COMMERCIAL
BUILDINGS

LOCAL ROADS AND
STREETS

0.6-2.0 0.6-2.0 0.06-0.2 0.2-0.6 0.2-0.6 <0.06 0.06-0.6

4.5-5.5 4.5-6.0 4.5-5.5 5.1-7.8 4.5-5.5 4.5-5.5 4.5-7.3

Low Low Mod. Mod. Mod. Mod. High

Mod. Mod. High Mod. High High High

Mod.

2.0-3.0

>60

High

>6.0

>60

High

>6.0

>60

None Rare Occ
None Rare
None

Mod.

>6.0

10-20

Mod.

2.5-3.5

>60

Mod.

0-1.0

>60

None
None Rare Occ
None

Mod.

>6.0

20-40

None

C

None, Rare: S; w None, Rare: S; w

S; w

Occ: S; w, f

Occ: S; f, w

None: M; w# None: S; w* Occ: S; f, w

0-4%: None: M; w 4-6%: None: M; w, s
Rare, Occ: S; f

0-8%: L

0-7%: M; p, s

0-8%: M; ss

B

8-15%: M; s

7+%: S; s

0-8%: L

8-15%: M; s, ss

Rare: M; f

Rare: S; f

8-15%: M; s

Rare: S; f

B

S; pk, pf

0-7%: S; p

0-8%: M; cc

0-8%: M; ss

7+%: S; s, p

8-12%: M; s, cc

8-12%: M; s, ss

0-4%: L 4-8%: M; s 8+%: S; s Rare: S: s, f
0-4%: L 4-8%: M; s 8-12%: S; s

2-15%: M; ss, r#

C

2-15%: S; r

2-7%: S; r

2-15%: S; r

15+%: S; s, r

7+%: S; s, r

15+%: S: s, r

15+%: S; s# 2- 15%: S; r* 15+%: S; r, s*

2-8%: M; r, ss 8+%: S; s

0-7%: None: S; w

0-8%: None: M; w, ss

0-8%: None: M; ss

C

None, Rare: S; w, pk

7+%: None: S; w, s 0-7%Rare, Occ: S; w, f

None, Rare: M; cl, w 8-15%: None: M; w, ss, s

8+%: None: S; s 0- 8%: Rare, Occ: S; f

Occ: S; f, w, pk

7+%Rare, Occ: S; l, w, s

Occ: M; cl, w, f

Rare, Occ: S, -f

8+%: Rare:, Occ: S, f, s

0-2%: L

D

S; pk, w

2-7%: M; s

S; w

S; w

S; w

7+%: S; s

C

2-15%: S; r, pk

2-7%: S; r

15+%: S; r, pk, s

7+%: S; r, s

2-15%: S; r 15+%: S; r, s

2-15%: S; ss# 15+%: S; ss, s# 2-15%: S; r, ss* 15+%: S, r, ss, s*

2-8%: S; ss 8+%: S; s, ss

None: M; w Rare: M; w, f
Occ: S; f 0-8%: L 8-15%: M; s Rare: M; f
0-8%: L 8-12%: M; s 2-8%: M; r, ss 8-15%: M; s, r, ss 15+%: S; s
None, Rare: S; b Occ: S; b, f
S; w, b
2-15%: S; b, ss 15+%: S; b, ss, s

GaSWCC

B-1-39

SOIL SERIES INTERPRETATIONS

ESTIMATED SOIL PROPERTIES

SOIL SERIES Allanton

CORROSIVITY

DEPTH TO:

SOIL SHRINK-

WATER

FLOOD

PERMEABILITY REACTION SWELL STEEL CONCRETE TABLE BEDROCK FRE- HYDRO-

(In./Hrs.)

(pH) POTENTIAL

(Ft.)

(In.) QUENCY GROUP

SEPTIC TANK ABSORPTION
FIELDS

2.00-6.00

3.6-5.5

Low

High

High

-2.0-0.0

>60

None

D

S; p

Arkabutla
Badin Bethera

0.60-2.00
0.60-2.00 0.06-0.60

4.5-5.5
3.5-6.5 3.6-6.0

Low

High

Low Moderate

High High

High
High High

1.0-1.5

>60 Occasional

C

>6.0

20-40

None

B

0.0-1.5

>60 Occasional

D

S; f, w
2-10%: S; r 10+%: S; r, s
S; f, w, pk

Blaney

0.20-0.60

4.5-6.0

Low

Moderate

High

>6.0

>60

None

B

S; pk, pf

Buckhead
Cheoah Chestnut Craigsville

0.60-2.00
2.00-6.00 2.00-6.00 2.00-20.00

4.5-6.5
3.5-5.5 3.6-6.0 4.5-5.5

Low

Moderate

High

>6.0

>60

None

B

Low

Low

High

>6.0

40-60

None

B

Low

Low

High

>6.0

20-40

None

B

Low

Low

Moderate

>6.0

>60

Frequent

B

M; s 5-15%: M; r, s,
15+%: S; s S; r, s
S; f, pf, st

Fork Jefferson Ketona

0.60-2.00 2.00-6.00 0.06-0.20

4.5-7.3 4.5-5.5 6.1-8.4

Low

High

High

1.0-2.0

>60 Occasional

C

Low

Moderate

High

>6.0

>60

None

B

High

High

Moderate 0.5-1.0

40-72

Frequent

D

S; f, w S; s S; f, w, pk

Kingsferry Lloyd

0.6-2.00 0.60-2.00

3.6-5.5 4.5-6.5

Low

High

High

0.0-0.5

>60

Low

Moderate Moderate

>6.0

>60

None None

B/D

S; w, pf

2-15%: M; pk, s

B

15+%: S; s

Pageland Panama

0.20-0.60 0.60-2.00

3.6-6.0

Low

Moderate Moderate 1.5-3.0

20-40

None

C

4.5-6.0

Low

Moderate

High

3.5-5.0

>80

None

B

S; r, w, pk S; w, pk, s

Pigeonroost Rawlings Saunook Sedgefield Shelocta
Sipsey Wake Wateree Wynott

0.60-2.00 0.60-6.00 0.60-2.00 0.06-0.20 0.60-2.00
0.60-2.00 6.00-20.00 2.00-6.00 0.06-0.20

3.5-6.0

Low

Moderate

High

>6.0

20-40

None

B

4.5-7.3

Low

Moderate

High

>6.0

20-40

None

B

3.6-6.5

Low

Low

High

>6.0

>60

None

B

4.5-6.5

Moderate

High

Moderate 1.0-1.5

>60

None

C

4.5-5.5

Low

Low

High

>6.0

>40

None

B

4.5-6.0

Low

Moderate

High

>6.0

20-40

None

B

4.5-6.0

Low

Moderate Moderate

>6.0

8-20

None

D

4.5-6.0

Low

Low

High

>6.0

20-40

None

B

4.5-6.5

Low

High

Moderate

>6.0

20-40

None

C

S; r
S; r S; s S; w, pk M; pk, s
S; r, s 2-10%: S; r 10+%: S; r, s
S; r S; r, pk, s

GaSWCC

LIMITATION OF SOILS FOR URBAN USES

SEWAGE LAGOON AREAS
S; p

SHALLOW EXCAVATIONS
S; cc, p

S; f, w
2-10%: S; r 10+%: S; r, s
S; f, w

S; w
M; r, cl S; w

S; p

S; cc

S; p, s

S; cc

S; p, s S; p, r, s S; p, f, st

M; s S; s S; cc, st

S; f, w

S; w

S; p, s

S; s

S; f

S; w

S; p, w
2-6%: M; p, s 6+%: S; s

S; cc, w M; cl, s

S; r, w

S; w

S; s

S; s

S; r, s S; p, r, s S; p, s
S; s S; p, s

M; r, s S; r S; s S; w M; s

S; p, r, s S; p, r S; p, r S; p, r, s

M; r, s S; r S; cc S; s

DWELLINGS *w/basement #w/o basement
S; p
S; f, w M; r, ss* M; ss# S; f, w
L
M; s
M; s S; s
S; f, st
S; f, w
S; s
S; f, w, ss
S; w
L S; w* MS; w# S; s M; r, s* M; s# S; r* M; s, r# S; s
S; w, ss
M; s M; r, s* M; s#
S; r M; r* L# S; ss, s

SMALL COMMERCIAL
BUILDINGS S; p S; f, w
M; ss, s S; f, w M; s S; s S; s S; s S; f, st S; f, w S; s S; f, w, ss S; w
M; s M; w S; s
S; s S; s S; s S; w, ss, s S; s
S; s S; r M; s S; ss, s

LOCAL ROADS AND
STREETS S; p S; b, f
S; b S; b, w, f
L M; s M; s S; s S; f, st S; f S; s S; ss, b, w S; w
M; b S; b S; s
M; s M; r, s S; s S; ss, b M; s
M; s S; r L S; ss, b, s
B-1-41

APPENDIX B-2

Estimating Soil Erosion With the Universal Soil Loss Equation (USLE)

Scientific planning for soil erosion reduction requires knowledge of the relations between those factors that cause loss of soil and water and those that help to reduce such losses. The Universal Soil Loss Equation (USLE) is used to estimate the quantity of soil erosion (sheet and rill) caused by water and to design water erosion control systems.
Developing equations to calculate field soil loss began about 1940 in the Corn Belt. The USLE was developed by the USDA Agricultural Research Service (ARS) and 49 research locations across the U.S. contributed more than 10,000 plot years of basic runoff and soil loss data to ARS for summarizing and overall statistical analyses. Since the early 1960's, the USDA Natural Resources Conservation Service (formerly the Soil Conservation Service) and others have used the USLE to predict soil losses and to plan conservation treatment.
The USLE permits methodical decision making in soil conservation planning on a site basis. The USLE was designed to predict long-term average annual soil losses from sheet and rill erosion on given field slopes under specified land use and management.
Many variables and interactions influence sheet and rill erosion. The USLE groups these variables under six major erosion factors, the product of which represents the average annual soil loss.
The soil loss predicted by the USLE is that of soil moved off the particular slope segment in sheet and rill erosion. Sheet erosion is defined as the removal of layer of soil from the land surface by the action of rainfall and runoff. It is the first stage in water erosion. This is followed by rill erosion. Rills are small, occur in cropland situations, are removed by normal farming operations, and usually do not reoccur in the same place.
Widespread use of the USLE has substantiated its usefulness and validity for cropland, pasture and hay land, forest land and for non-agricultural conditions such as construction sites.
The USLE does not predict sediment deposition or soil erosion caused by gully, streambank, streambed, mass movement, or wind erosion.
GaSWCC (Amended - 1995)

Detailed instructions for using the USLE are in Agriculture Handbook No. 537, USDA, Predicting Rainfall Erosion Losses.
The USLE is:
A = R K L S C P
A is the computed average annual soil loss in tons per acre per year.
R is the rainfall factor. The R factor value quantifies the raindrop impact effect. Rainfall energy is directly related to rain intensity. The energy of a rainstorm is a function of the amount of rain and of all the storm's component intensities. Median raindrop size increases with rain intensity and the terminal velocity of free-falling waterdrops increase with increased dropsize.
The R factors assigned represent 22-year average annual values for the delineated areas. In Georgia, USLE R factor values range from 250 to 425. They are listed by county on Table B-2.1, p. B-2-4.
K is the soil erodibility factor. Some soils erode more readily than others even when all other factors are the same. The K factors assigned to soils found in Georgia range from 0.05 to 0.43 and may be obtained from the USDA Natural Resources Conservation Service.
LS is the topographic factor. Both the length and the steepness of the land slope substantially affect the rate of soil erosion by water.
Slope length is defined as the distance from the point of origin of overland flow of water to the point where either the slope gradient decreases enough that deposition begins, or the runoff water enters a well-defined channel (terrace channel, concentrated flow area, gully, ditch, grass waterway, etc.). It is not the total length or width of the field in most cases.
The two effects have been evaluated separately in research. In field applications, however, the two are considered as a single topographic factor. LS factors are listed in Table B-2.2, p. B-2-6.
B-2-1

C is the cover and management factor. C is the ratio of soil loss from land with a specified type and amount of cover to the corresponding loss from a clean tilled, continuous fallow site. The C for a continuous fallow condition is 1.00. Any amount of ground cover present (canopy or residue) reduces the C factor and the soil loss for the site. C factor values are listed for different land uses in Table B-2.3 through B-2.5, p. B-2-7 through B-2-10.
P is the support practice factor. P is the ratio of soil loss with a specific support practice to the corresponding loss with up-and-down slope farming. The maximum P factor value is 1.00. Conservation practices that reduce the P factor are contour farming, cross-slope farming, and stripcropping. P is used only in USLE calculations for row cropped land. In all other land uses, the P is always 1.00.
Soil Loss Tolerance
The term "soil loss tolerance", sometimes called the "T" value, denotes the maximum level of soil erosion that will permit a high level of crop productivity to be sustained economically and indefinitely. Any cropping and management combination for which the predicted erosion rate is less than the tolerance may be expected to provide satisfactory erosion control. Soil loss tolerances range from 1 to 5 tons/acre/year for soils of the U.S.
Soil loss limits are sometimes established primarily for water quality control. The criteria for defining field soil loss limits for this purpose are not the same as those for tolerances designed to preserve cropland productivity. If the soil loss tolerance designed for sustained cropland productivity fails to attain the desired water quality standard, flexible limits that consider other factors should be developed rather than uniformly lowering the soil loss tolerance. Limits of sediment yield would provide more uniform water quality control than lowering the limits on soil movement from field slopes.
Sample Problem #1
Present Condition (Before Treatment):
Location: Cobb County, GA (R = 300) Land Use: Cropland, Soybeans, Conventionally Tilled (C = 0.46) Soil Type: Cecil sandy loam (K = 0.28) Length of Slope: 120 feet Slope: 5% (LS = 0.59) Row Pattern: Up and Down Hill Farming (P = 1.0)
A = RKLSCP A = 300 x 0.28 x 0.59 x 0.46 x 1.0 = 22.8 tons/acre/year
B-2-2

Future Condition (After Treatment):
Location: Cobb County, GA (R = 300) Land Use: Tall fescue pasture, 95 - 100% cover (C = 0.003) Soil Type: Cecil sandy loam (K = 0.28) Length of Slope: 120 feet Slope: 5% (LS = 0.59)
A = RKLSCP A = 300 x 0.28 x 0.59 x 0.003 x 1.0 = 0.15 tons/acre/year
Sample Problem #2
Present Condition (Before Treatment):
Location: Thomas County, GA (R = 400) Land Use: Disturbed Construction Site (C = 1.0) Soil Type: Orangeburg sandy loam (K = 0.24) Length of Slope: 120 feet Slope: 20% (LS = 4.47)
A = RKLSCP A = 400 x 0.24 x 4.47 x 1.0 x 1.0 = 429 tons/acre/year
Future Condition (After Treatment):
Location: Thomas County, GA (R = 400) Land Use: Weeping lovegrass (60% cover) (C = 0.042) Soil Type: Orangeburg sandy loam (K = 0.24) Length of Slope: 120 feet Slope: 20% (LS = 4.47)
A = RKLSCP A = 400 x 0.24 x 4.47 x 0.042 x 1.0 = 18 tons/acre/year
Additional Soil Erosion Prediction Models
Revised Universal Soil Loss Equation (RUSLE)
The revised Universal Soil Loss Equation (RUSLE) has been developed by USDA/ARS. The RUSLE retains the six factors of the USLE, but the technology has been altered and new data has been added. The technology has been computerized to assist with the calculations. Soil loss calculations can be made with the RUSLE for some conditions not included in the USLE if the fundamental information is available.
Copies of the RUSLE program may be purchased from:
Soil and Water Conservation Society of America 7515 N.E. Ankeny Road Ankeny, Iowa 50021-9764 Phone: (515) 289-2331
1-800-THE-SOIL
GaSWCC (Amended - 1995)

Water Erosion Prediction Project (WEPP)
The development of a new generation of technology for predicting water erosion is under way by a USDA team in the Water Erosion Prediction Project (WEPP). Working with other agencies and academic institutions, the goal of the WEPP is a process oriented model or family of models that are conceptually superior to the lumped model RUSLE and are more versatile as to the conditions that can be evaluated. The WEPP technology is expected to replace RUSLE sometime in the future.

GaSWCC (Amended - 1995)

B-2-3

County Appling Atkinson Bacon Baker Baldwin Banks Barrow Bartow Ben Hill Berrien Bibb Bleckley Brantley Brooks Bryan Bulloch Burke Butts Calhoun Camden Candler Carroll Catoosa Charlton Chatham Chattahoochee Chattooga
B-2-4

Table B-2.1 - Rainfall-Erosion Index Factor "R" Values

R

County

R

County

R

350

Cherokee

300

Fannin

275

325

Clarke

275

Fayette

300

350

Clay

375

Floyd

300

375

Clayton

300

Forsyth

275

275

Clinch

350

Franklin

300

300

Cobb

300

Fulton

300

275

Coffee

325

Gilmer

275

300

Colquitt

350

Glascock

250

325

Columbia

250

Glynn

400

350

Cook

350

Gordon

300

300

Coweta

325

Grady

400

300

Crawford

300

Greene

250

375

Crisp

325

Gwinnett

300

375

Dade

275

Habersham

300

350

Dawson

275

Hall

275

325

Decatur

425

Hancock

250

275

DeKalb

300

Haralson

325

300

Dodge

300

Harris

325

375

Dooly

325

Hart

275

400

Dougherty

350

Heard

325

300

Douglas

300

Henry

300

325

Early

400

Houston

300

275

Echols

350

Irwin

325

375

Effingham

350

Jackson

275

350

Elbert

250

Jasper

275

350

Emanuel

300

Jeff Davis

325

300

Evans

325

Jefferson

275

GaSWCC (Amended - 1995)

County

R

Jenkins

300

Johnson

300

Jones

275

Lamar

300

Lanier

350

Laurens

300

Lee

350

Liberty

350

Lincoln

250

Long

350

Lowndes

350

Lumpkin

275

McDuffie

250

Mclntosh

400

Macon

325

Madison

275

Marion

325

Meriwether

325

Miller

400

Mitchell

375

Monroe

300

Montgomery

300

Morgan

275

Murray

275

Muscogee

325

Newton

300

Oconee

275

Oglethorpe

250

GaSWCC (Amended - 1995)

County Paulding Peach Pickens Pierce Pike Polk Pulaski Putnam Quitman Rabun Randolph Richmond Rockdale Schley Screven Seminole Spalding Stephens Stewart Sumter Talbot Taliaferro Tattnall Taylor Telfair Terrell Thomas Tift

R

County

300

Toombs

300

Towns

275

Treutlen

350

Troup

325

Turner

300

Twiggs

300

Union

275

Upson

375

Walker

300

Walton

350

Ware

250

Warren

300

Washington

325

Wayne

300

Webster

425

Wheeler

300

White

300

Whitfield

350

Wilcox

325

Wilkes

325

Wilkinson

250

Worth

325

325

325

350

400

350

R 325 300 300 325 325 300 300 325 275 275 350 250 275 375 350 300 300 275 325 250 275 350
B-2-5

GaSWCC (Amended - 1995)

B-2-6

U.S. DEPARTMENT OF AGRICULTURE Soil Conservation Service Athens, Georgia

Table B-2.2 - Slope-Effect Table (Topographic Factor, LS)

Percent Slope

Slope Length in Feet 10 20 40 60 80 100 120 140 160 180 200 250 300 350

0.5

0.05 0.06 0.08 0.08 0.09 0.10 0.10 0.11 0.11 0.12 0.12 0.13 0.14 0.14

1.0

0.06 0.08 0.10 0.11 0.12 0.13 0.14 0.14 0.15 0.15 0.16 0.17 0.18 0.19

2.0

0.10 0.12 0.15 0.17 0.19 0.20 0.21 0.22 0.23 0.24 0.25 0.26 0.28 0.29

3.0

0.14 0.18 0.22 0.25 0.27 0.29 0.30 0.32 0.33 0.34 0.35 0.38 0.40 0.42

4.0

0.16 0.21 0.28 0.33 0.37 0.40 0.43 0.46 0.48 0.51 0.53 0.58 0.62 0.66

5.0

0.17 0.24 0.34 0.41 0.48 0.54 0.59 0.63 0.68 0.72 0.76 0.85 0.93 1.00

6.0

0.21 0.30 0.43 0.52 0.60 0.67 0.74 0.80 0.85 0.90 0.95 1.06 1.17 1.26

7.0

0.26 0.37 0.52 0.64 0.74 0.83 0.90 0.98 1.04 1.11 1.17 1.30 1.43 1.54

8.0

0.31 0.44 0.63 0.77 0.89 0.99 1.09 1.17 1.25 1.33 1.40 1.57 1.72 1.86

9.0

0.37 0.52 0.74 0.91 1.05 1.17 1.29 1.39 1.48 1.57 1.66 1.86 2.03 2.20

10.0 (10:1) 0.43 0.61 0.87 1.06 1.23 1.37 1.50 1.62 1.73 1.84 1.94 2.17 2.37 2.56

12.0

0.57 0.81 1.14 1.40 1.61 1.80 1.98 2.14 2.28 2.42 2.55 2.85 3.13 3.38

14.0

0.73 1.03 1.45 1.78 2.05 2.29 2.51 2.72 2.90 3.08 3.25 3.63 3.98 4.29

16.0

0.90 1.27 1.80 2.20 2.54 2.84 3.11 3.36 3.59 3.81 4.01 4.49 4.92 5.31

18.0

1.09 1.54 2.17 2.66 3.07 3.43 3.76 4.06 4.34 4.61 4.86 5.43 5.95 6.43

20.0 (5:1) 1.29 1.82 2.58 3.16 3.65 4.08 4.47 4.83 5.16 5.47 5.77 6.45 7.07 7.63

25.0 (4:1) 1.86 2.63 3.73 4.56 5.27 5.89 6.45 6.97 7.45 7.90 8.33 9.31 10.20 11.02

30.0

2.52 3.56 5.03 6.16 7.11 7.95 8.71 9.41 10.06 10.67 11.25 12.58 13.78 14.88

33.33 (3:1) 2.99 4.22 5.97 7.32 8.45 9.45 10.35 11.18 11.95 12.67 13.36 14.93 16.36 17.67

40.0 (2 1/2:1) 4.00 5.66 8.00 9.80 11.32 12.65 13.86 14.97 16.01 16.98 17.90 20.01 21.92 23.67

50.0 (2:1) 5.64 7.97 11.27 13.81 15.94 17.82 19.53 21.09 22.55 23.91 25.21 28.18 30.87 33.35

60.0

7.32 10.35 14.64 17.93 20.71 23.15 25.36 27.39 29.29 31.06 32.74 36.61 40.10 43.31

66.67 (1 1/2:1) 8.43 11.93 16.87 22.66 23.85 26.67 29.21 31.56 33.73 35.78 37.72 42.17 46.19 49.89

Section I All Resource Areas
Georgia November 1980
400 500 600 800 1000 0.15 0.16 0.17 0.18 0.20 0.20 0.21 0.22 0.24 0.26 0.31 0.33 0.34 0.38 0.40 0.44 0.47 0.49 0.54 0.57 0.70 0.76 0.82 0.92 1.01 1.07 1.20 1.31 1.52 1.69 1.35 1.50 1.65 1.90 2.13 1.65 1.84 2.02 2.23 2.51 1.98 2.22 2.43 2.81 3.14 2.35 2.62 2.87 3.19 3.57 2.74 3.06 3.36 3.87 4.33 3.61 4.04 4.42 5.10 5.71 4.59 5.13 5.62 6.49 7.26 5.68 6.35 6.95 8.03 8.98 6.87 7.68 8.41 9.71 10.86 8.16 9.12 9.99 11.54 12.90 11.78 13.17 14.43 16.66 15.91 17.79 19.48 22.50 18.89 21.12 25.31 28.30 35.65 39.86 46.30 51.77 53.34 59.63

GaSWCC (Amended - 1995)

Rotation Cycle (Years)

Crop Sequence

Table B-2.3 - Crop Management "C" Factors for Georgia (All Medium Yields)

Section I All Resource Areas
Georgia March 1984

Conventional Tillage Systems
RdL RdR

Conservation Tillage Systems

All Crops Con-

No-till1

servation Tilled

Systems

30%2 50% 70%

Combinations of Tillage Systems

Summer Crop Conven. Summer Crop Cons.Till.

& Winter Cons. Till.

& Winter Conventional

30% 50% 70% 30% 50% 70%

1

Corn

0.33 0.50

0.07

0.15 0.11 0.07

-4

-

-

-

-

-

1

Corn & Small Grain

0.31 0.44

0.04

0.16 0.11 0.08 0.30 0.29 0.28 0.17 0.14 0.13

1

Cotton

0.48 0.54

0.23

0.25

-

-

-

-

-

-

-

-

1

Cotton & Small Grain 0.45 0.52

0.18

0.22

-

-

0.48

-

-

0.24 0.22 0.21

1

Grain Sorghum

0.37 0.55

0.12

0.22 0.17 0.12

-

-

-

-

-

-

1

Grain Sorghum &

Small Grain

0.32 0.42

0.06

0.15 0.10 0.07 0.30 0.29 0.28 0.16 0.13 0.11

1

Peanuts

0.46 0.58

0.27

0.27

-

-

-

-

-

-

-

-

1

Peanuts & Small Grain 0.38 0.44

0.07

0.16 0.11

-

0.40

-

-

0.19 0.16 0.13

1

Soybeans

0.46 0.60

0.27

0.27

-

-

-

-

-

-

-

-

1

Soybeans & Small Grain 0.41 0.54

0.08

0.19 0.12

-

0.35

-

-

0.23 0.19 0.17

1

Tobacco

0.41 0.44

0.17

0.21

-

-

-

-

-

-

-

-

1

Tobacco & Small Grain 0.41 0.43

0.16

0.23 0.19

-

0.35 0.34

-

0.26 0.22 0.20

1

Millet

0.27 0.52

0.09

0.13 0.11 0.09

-

-

-

-

-

-

1

Millet & Small Grain

0.25 0.30

0.05

0.10 0.08 0.05 0.22 0.21 0.20 0.14 0.12 0.10

1

Small Grain3

0.13 0.26

0.07

0.09 0.08 0.07

-

-

-

-

-

-

1 The soil is left undisturbed prior to all plantings. Planting is completed in a narrow seedbed. Weeds are controlled primarily with herbicides.

2 Percent of soil surface covered by crop residues immediately following planting.

3 Followed by weeds.

4 Does not apply, or either the crops do not provide this much residue.

NOTE: Add 0.05 to the "C" value when the cover crop is grazed. For example: "C" for Corn & Small Grain (conven.)

=0.31

If grazed, add 0.05

+0.05

Use "C" value of

0.36

B-2-7

U.S. Department of Agriculture Soil Conservation Service

Section I All Resource Areas
Georgia April 1981

Table B-2.4 - Average Annual "C" Factor Values "C" Factors for Undisturbed Forest Land1

Percent of area covered by canopy of trees and undergrowth

Percentof area covered by duff

Factor "C" 2

100-75 70-45 40-20

100-90 85-75 70-40

.0001-.001 .002-.004 .003-.009

1 Where effective litter cover is less than 40 percent or canopy cover is less than 20 percent, use factors from Table II. Also use Table II where woodlands are being grazed, harvested, or burned.
2 The ranges listed in "C" values are caused by ranges in the specified forest litter and canopy covers and by variations in effective canopy heights. Use lower range where heavy ground litter is present or where low understory vegetation is dense.

B-2-8

GaSWCC (Amended - 1995)

U.S. Department of Agriculture Soil Conservation Service

Section I All Resource Areas
Georgia March 1984

Table B-2.5 - Average Annual "C" Factor Values Factors for Perennial Pasture, Idle Land, or Grazed Woodland1

Vegetative Canopy

Type and Height of

Canopy Cover3

Raised Canopy2

%

Type4

Cover That Contacts the Surface

Percent Ground Cover

0

20 40 60 80 95-100

No appreciable canopy

G

.45 .20 .10 .042 .013 .003

W

.45 .25 .15 .090 .043 .011

Canopy of tall weeds or short brush (0.5m or 20 inches fall height)

25

G

.36 .17 .09 .038 .012 .003

W

.36 .20 .13 .082 .041 .011

50

G

.26 .13 .07 .035 .012 .003

W

.26 .16 .11 .075 .039 .011

75

G

.17 .10 .06 .031 .011 .003

W

.17 .12 .09 .068 .038 .011

Appreciable brush or brushes (2m or 79 inches fall height)

25

G

.40 .18 .09 .040 .013 .003

W

.40 .22 .14 .085 .042 .011

50

G

.34 .16 .09 .038 .012 .003

W

.34 .19 .13 .081 .041 .011

75

G

.28 .14 .08 .036 .012 .003

W

.28 .17 .12 .077 .040 .011

Trees but no appreciable low brush (4m or 157 inches fall height)

25

G

.42 .19 .10 .041 .013 .003

W

.42 .23 .14 .087 .042 .011

50

G

.39 .18 .09 .040 .013 .003

W

.39 .21 .14 .085 .042 .011

75

G

.36 .17 .09 .039 .012 .003

W

.36 .20 .13 .083 .041 .011

1 The listed "C" values assume that the vegetation and mulch are randomly distributed over the entire area.

2 Average fall height of waterdrops from canopy to soil surface: m = meters.

3 Portion of total-area surface that would be hidden from view by canopy in a vertical projection (a bird's-eye view).

4 G: Cover at surface is grass, grasslike plants, or decaying compacted duff.

W: Cover at surface is mostly broadleaf herbaceous plants (as weeds with little lateral-root network near the surface) or unde-cayed residues or both.

GaSWCC (Amended - 1995)

B-2-9

Section Ill-B All Resource Areas
Georgia March 1984

Table B-2.6 - "C" Factors and Slope Lengths for Construction Sites

Type Cover

Tons/Acre

Slope Per Cent

C Value

Maximum Allowable Slope Length

Bare (No cover) Straw1 2 (Tied down by
anchoring equipment)
Crushed Stone (Road gravel)
Wood Chips2
Seeding Temporary or (permanent
with fast-growing grass)

-

All

1.0

-

1

5

.20

200

6-10

.20

100

1.5

5

.12

300

6-10

.12

150

2.0

5

.06

400

6-10

.06

200

11-15

.07

150

16-20

.11

100

21-25

.14

75

26-50

.18

35

60

15

.07

200

135

15

.05

200

16-20

.05

150

21-33

.05

100

34-50

.05

75

240

20

.02

300

21-33

.02

200

7

15

.08

75

16-20

.08

50

12

15

.05

150

16-20

.05

100

21-33

.05

75

25

15

.02

200

16-20

.02

150

21-33

.02

100

Mulch

C Value for Cover Stages

3-5 weeks

4-10 weeks3

0 1 T/Ac Straw 1 1/2 t/Ac Straw

.50 -.70 .20 .12

.05-.10 .07 .05

Permanent Seedings - Remainder of first year -.05 Permanent Seedings - Second Year -.01 Sod - Immediately -.01

1 Double the C value if straw not anchored to control rilling beneath the mulch on soils having a K value greater than .30 or slopes steeper than 10 percent.
2 The effective life of all mulches except stone will vary from 2 months to 6 months. Thereafter, the C value for mulches reverts to 1.0 if vegetation is not established.
3 The plants used, time of seeding, temperature, moisture, and fertility all affect establishment time of vegetation.

B-2-10

GaSWCC (Amended - 1995)

GUIDE FOR DEVELOPING THE SOIL ERODIBILITY FACTOR (K) IN THE UNIVERSAL SOIL LOSS EQUATION
The soil erodibility factor (K) used in the universal soil loss equation is a measure of the susceptibility of soil particles to detachment and transport by rainfall and runoff. It is a value determined experimentally for selected benchmark soils. Based on knowledge of the behavior of soil properties and their interactions, these data are synthesized and values assigned to other kinds of soil.
A single K value can be given the dominant textural phase of a soil series if the erosion potential is about the same for all horizons and textural phases of that series. Where horizons or textural phases of a series differ greatly in erosion potential, say two or more K value classes, more than one K value needs to be assigned to the named kind of soil.
K values that have been obtained experimentally range from .01 to .64. For ease of use, twelve K value

classes are used as follows: .10, .15, .17, .20,.24, .28,.32,.37, .43, .49, .55 and .64.
In developing K values for soils, use all applicable data. In addition, consider the following soil properties that have been found to affect soil erodibility:
1. Soil texture, especially percent of silt plus very fine sand.
2. Percent of sand greater than 0.10 mm.
3. Soil organic matter content.
4. Soil structure (type, grade).
5. Soil permeability.
6. Clay mineralogy.
7. Coarse fragments in soil layer being evaluated.
Rainfall intensity, distribution, amount, length and steepness of slope, vegetative cover and erosion control practices all influence soil erodibility but these are taken care of by other variables in the equation.

FIRST APPROXIMATION OF K

0

10

90

20

80

30

70

.70

.60

%OM=0

12 3

.50

4

.40

* 1 - very fine granular 2 - fine granular 3 - medium or coarse granular 4 - blocky, platy, or massive
*SOIL STRUCTURE 1 2 3 4

60

40

.30

PERCENT SILT + VERY FINE SAND

50

50

.20 .70

60

40

.10 .60

70

30

0 .50

SOIL-ERODIBILITY FACTOR, K

80

PERCENT SAND

(0.10-2.0mm)

20

15

90

10

5 0

100

PROCEDURE: With appropriate data, enter scale at left and proceed to points representing the soil's % sand (0.10-2.0mm), % organic matter, structure, and permeability, in that sequence. Interpolate between plotted curves. The dotted line illustrates procedure for a soil having: sf + vsf 65%, sand 5%, OM 2.8%, structure 2, permeability 4. Solution: K=0.31

.40 .30 .20 .10

#6 5 4 3 2 1 PERMEABILITY
# 6 - very slow 5 - slow 4 - moderate to rapid 3 - moderate 2 - moderate to rapid 1 - rapid

0

W.H. Wischmeler, ARS-SWC, Purdue Univ. 2-1-71

Reprinted from the Journal of Soil and Water Conservation September-October 1971, Volume 26, Number 5

GaSWCC (Amended - 1995)

Figure B-2.1 - Soil Erodibility Nomograph

B-2-11

The Agricultural Research Service has developed a nomograph which shows the influence of various selected soil properties on K values (42). A copy of this nomograph is attached for information and guidance.
When using the nomograph, care should be taken to select those soil properties that are most representative of the horizon being considered. For horizons having organic matter in excess of 4 percent, do not extrapolate - use the 4 percent curve.
The K values derived from the nomograph must be adjusted for coarse fragments. K values for soils high in coarse fragments (gravelly, chanery, shaly, slaty. cherty, cobbly, or flaggy) are reduced by one or two classes. Soils that are very gravelly, very chanery, very shaly, very slaty, very cherty, very cobbly or very flaggy are reduced by two or three classes.
Soil scientists using the ARS nomograph have noted that for some soils, the K values obtained from the nomograph differ from those they have been using for many years. The nomograph commonly gives higher K values for silty soils and lower values for soils high in clay and in sand than values now in use. Where these values differ more than two K value classes, there is need to study the soils carefully and see how they behave under field conditions. For some soils, the best value may be somewhere between these two values. For other soils, the original estimated value may be more representative. The nomograph is based on a limited number of different kinds of soil and experience with its use is limited. Therefore, it should be used only as a guide at this time.

B-2-12

GaSWCC (Amended - 1995)

APPENDIX C
Riprap
DEFINITION
A revetment of loose rock or similar material installed on a cut or fill slope or a channel side slope to protect the slope from erosion.
PURPOSE
The purpose of the riprap is to provide a protective, non-erosive cover on a slope.
CONDITIONS
This standard applies to channels where velocities do not exceed 10 feet per second or to cut or fill slopes where soil conditions, water turbulence and velocity are such that it will not be stable.
DESIGN CRITERIA
An appropriate geotextile fabric shall be placed between the riprap and soil base. Use NRCS, DOT or the manufacturer's specifications for type and weight of fabric.
The toe of the revetment shall be entrenched in stable channel bottoms for a depth of 1.5 to 3 feet depending on the size of the riprap.
Riprap shall extend up the bank to an elevation where vegetation will provide adequate protection.
For channels, riprap shall be sized as required by channel velocity at full bank flow. Use Table C-1 and Figure C-1. The filter size is also shown in Table C-1.
Riprap shall not be placed on slopes steeper than 1.5 horizontal to 1.0 vertical.
The stone should be reasonably well graded within the gradation curves for each size designated, and any stone gradation, as determined from a field test sample, that lies within these limits shall be acceptable.
The designer should establish the size of graded quarry stone required for the project using acceptable design criteria. Consideration should then be given to using one of the standardized sizes contained in the following tables.
GaSWCC (Amended - 2000)

The thickness of the graded quarry stone layer and the gradation are interrelated. The thickness specified normally will vary form 1.0 to 1.5 times the maximum stone size in the gradation. In high turbulence areas, the layer thickness should be 1.5 times the maximum stone size. In low turbulence areas, the layer thickness can be reduced to the dimension of the largest stone in the gradation band.
CONSTRUCTION SPECIFICATIONS
The channel side slope and the toe excavation shall be prepared to the required lines and grades.
Filter material and riprap shall be placed in succession to the required thicknesses and elevations. Riprap shall be handplaced around structures to prevent damage to the structures.
Terminology:
Graded Riprap - durable, dense, specifically selected and graded, quarried stone, placed to prevent erosion.
Filter Bedding Stone - stone generally less than 6 inches in size, that may be placed under graded riprap stone in a layer or combination of layers, designed and installed in such a manner as to prevent loss of underlying soil or finer materials because of moving water.
Surge Stone - a quarry run ungraded, unscreened material which may or may not have fines.
The standard sizes of quarried stone for erosion control specifications may be produced by any suitable commercial quarrying method and by the use of any type of sizing device, necessary to produce the desired sizes.
Standard sizes of stone for erosion and sediment control are defined by their weight or square sieve openings. In Georgia two stone classification systems exist: the National Stone Association (N.S.A.) classification and the Department of Transportation (D.O.T.) classification system. Each system separates the stone sizes into two categories: graded riprap stone sizes and filter bedding stone sizes.
N.S.A. Graded riprap stone sizes are shown in Table C-1.
N.S.A. Filter bedding stone sizes are shown in Table C-1 and C-2.
D.O.T. Graded riprap stone sizes are shown in Table C-3.
D.O.T. Filter bedding stone sizes are shown in Table C-4.
Data for stone center waterways are shown in Table C-5 and Figure C-3.
C-1

Table C-1 Graded Rip-Rap Stone

Flow Velocity (ft./sec.) 2.5 4.5 6.5 9.0 11.5 13.0 14.5

N.S.A. No.1 R-1 R-2 R-3 R-4 R-5 R-6 R-7

Max. 1 1/2
3 6 12 18 24 30

Size Inches (Sq. Opening)
Avg.2
3/4 1 1/2
3 6 9 12 15

Min. No. 8
1 2 3 5 7 12

1 National Stone Association 2 At least 50% of the individual stone particles must be equal or larger than this listed size

Filter Stone N.S.A. No.1
FS-1 FS-1 FS-2 FS-2 FS-2 FS-3 FS-3

C-2

GaSWCC (Amended - 2000)

N.S.A. No1 FS-1 FS-2 FS-3

Table C-2. Fitter Bedding Stone

Max. 3/8 2 6 1/2

Size Inches (Sq. opening) Avg.2
#30 mesh
#4
2 1/2

Min.3 #100 mesh #100 mesh
#16

1 National Stone Association 2 At least 50% of the individual stone particles must be equal or larger than this listed size 3 85 - 100% of the individual stone particles may be less than listed size

D.O.T. No.1 Type 3 Type 1

Table C-3. Graded Rip-Rap Stone

Size inches (Sq. opening)

Max.

Avg.

Min.

12

9

5

24

12

7

1 Georgia Department of Transportation

Common Uses Creek Banks Pipe Outlets Lakes & Shorelines Rivers

GaSWCC (Amended - 2000)

C-3

Table C-4. Filter Bedding Stone

D.O.T. No.1 3 4 5 6 57
1 Georgia Department of Transportation

Nominal Sizes (inches) 2" - 1"
1 1/2" - 3/4" 1" - 1/2" 3/4" - 3/8" 1" - No. 4

C-4

GaSWCC (Amended - 2000)

Maximum weight of stone required
(lbs.)
150 200 250 400 600 800 1000 1300 1600 2000 2700

Table C-5. - Gradation of Riprap
Minimum and maximum range in weight of stones (lbs.)
25 - 150 25 - 200 25 - 250 25 - 400 25 - 600 25 - 800 50 - 1000 50 - 1300 50 - 1600 75 - 2000 100 - 2700

Weight range of 75 percent of stones
(lbs.)
50 - 150 50 - 200 50 - 250 100 - 400 150 - 600 200 - 800 250 - 1000 325 - 1300 400 - 1600 600 - 2000 800 - 2700

Diameter of Stone in Inches Weight of Stone at 165 lbs./cu. ft.

60

15,000

10,000

40

5,000

1,000

20

500

250

100 50

0

0

2

4

6

8

10

12

14

16

18

20

Velocity in Feet/Sec.

Based on Isbash Curve

Figure C-1. - Maximum Stone Size for Riprap

GaSWCC (Amended - 2000)

C-5

Design depth "d" in feet
3.0

Max. Size - "D"75 75% of the Rock
in inches 100.0

Slope "S" of Drain
in %
20.0

2.5
2.0
1.5
1.0 d = 1.0 ft. 1.0 0.9 0.8 0.7 0.6 0.5

50.0

15.0

40.0

30.0

10.0

20.0

15.0

10.0

S = 5.0% 5.0

D75 = 7.9 in.

4.0

5.0

4.0

3.0

3.0

2.0

2.0

1.5 1.0

0.4

1.0

0.5

0.4

0.3

0.3

0.2

0.5

0.4

0.2

0.1

0.3

EXAMPLE: "d" = 1.0 Feet "S" = 5% Place straight edge at "d" value in Design Depth Column and at "S" value in Slope column. Read rock size in middle column 7.9 inches. Say 8 inches.

FOR DESIGN: 25% of the rock by volume should be in sizes of 8 inches or slightly larger. The remaining 75% or less should be of well graded material, smaller than 8 inches, including suffiecient sands and gravels to fill the voids between the larger rock.

Figure C-2. - Determination of Rock Size for Stone Center Waterway

C-6

GaSWCC (Amended - 2000)

Grade
V D
Q
20 25 30 35 40 45 50 55 60 65 70 75 80 90 100 110 120 130 140 150 160 170 180 190 200 220 240 260 280 300

Table C-6. - Velocity, Top Width and Depth for Parabolic Stone Center Waterways

6 Percent

8.0

10

1.3

1.6

6

7

7

8

9

9

10

7

11

7

12

8

13

9

14

10

16

11

17

11

19

12

20

13

22

14

23

15

25

16

26

17

27

18

29

19

32

21

35

23

38

25

40

27

43

29

8 Percent

8.0

10

1.1

1.3

10 Percent

8.0

10.0

1.0

1.2

Top Widths

5

5

6

6

7

7

8

5

8

9

6

9

6

10

7

9

6

11

7

10

7

12

8

11

7

12

9

12

8

13

9

13

9

14

10

14

9

15

10

15

10 17

12

17

11 19

13

19

13 21

14

21

14 23

16

22

15 25

17

24

16 27

18

26

17 29

20

27

18 31

21

29

19 33

22

31

20 34

23

32

22 36

25

34

23 38

26

38

25 42

29

41

27 46

31

44

30 50

34

48

32 54

36

51

34 57

39

12 Percent

8.0

10.0

0.9

1.1

5

6

7

8

5

9

6

10

6

11

7

12

8

13

8

14

9

15

10

16

10

18

11

20

13

22

14

24

15

26

17

29

18

31

19

33

21

35

22

37

24

39

25

42

26

44

28

48

31

53

33

57

36

61

39

66

42

15 Percent

8.0

10.0

0.8

0.9

5

6

4

7

5

8

6

10

7

11

7

12

8

13

9

14

9

16

11

17

11

18

12

19

13

21

15

24

16

26

18

29

20

31

21

33

23

36

24

38

26

40

28

43

29

45

31

47

33

52

38

57

39

62

42

67

45

71

49

GaSWCC (Amended - 2000)

C-7

STONE CENTER WATERWAYS

W

d

18"

4" to 12"

6"

GRAVEL BEDDING

Waterway with stone center drain V section shaped by motor patrol

W 2/3 W

d

4" to 12"

18"

6"

GRAVEL BEDDING

Waterway with stone center drain Rounded section shaped by bulldozer

Figure C-3 - Waterway with Stone Center

C-8

GaSWCC (Amended - 2000)

APPENDIX D
Model Soil Erosion and Sedimentation Control Ordinance

GaSWCC (Amended - 2001)

D-1

INSTRUCTIONS

This model ordinance contains 21 blanks which must be filled to complete certification. All the information entered, except for blanks 7 & 8, is considered substantive and necessary for implementation and compliance. Asterisks in the left and right margins of the pages indicate location of these blanks. Additionally, each blank is numbered and corresponds to the below listed guide.

Page Blank#

Information

3

1

Zoning Board, Council, County Commission, Official, Etc.

3

2

County or Municipality Name

3

3

County or Municipality Name (same as Blank #2)

3

4

District Names - available from the State Soil and Water Conservation Commission at (706) 542-3065

4

5

Appropriate District Name - available from the State Soil and Water Conservation Commission at (706) 542-3065 (same as Blank #4)

9

6

County or Municipality Name (same as Blank #2)

9

7

Office of Issuing Authority that processes permits

9

8

Office of Issuing Authority that processes permits (same as Blank #7)

9

9

Number of Copies

9

10

Dollar Amount

12

11

Office liable for collecting ad valorem taxes

12

12

Office of Issuing Authority that conducts inspections

12

13

Office of Issuing Authority that processes permits (same as Blank #8)

14

14

Zoning Board, Council, County Commission, Official, etc. (same as Blank #1)

14

15

Number of Days

14

16

County or Judicial Circuit

14

17

Day

14

18

Month

14

19

Year

14

20

Signature of Elected Official

14

21

Signature of Witness (usually clerk or recorded)

Upon adoption, a copy of the ordinance must be submitted for certification to the Georgia Department of Natural Resources Environmental Protection Division with an information copy to the State Soil and Water Conservation Commission at the following addresses:

Georgia Department of Natural Resources Environmental Protection Division Nonpoint Source Program Erosion and Sediment Control Unit Tradeport 4220 International Parkway, Suite 101 Atlanta, Georgia 30354 Telephone: (404)675-6240

State Soil and Water Conservation Commission P. O. Box 8024 Athens, Georgia 30603 Telephone: (706) 542-3065

D-2

GaSWCC (Amended - 2001)

Model Soil Erosion And Sedimentation Control Ordinance

NOW, THEREFORE, BE IT ORDAINED,

BY THE

(1)

OF

(2)

5

SECTION I TITLE

This ordinance will be known as

"

(3)

Soil Erosion and Sedimenta-

tion Control Ordinance."

SECTION II DEFINITIONS

The following definitions shall apply in the interpretation and enforcement of this ordinance, unless otherwise specifically stated:

1. Best Management Practices (BMP's): A collection of structural practices and vegetative measures which, when properly designed, installed and maintained, will provide effective erosion and sedimentation control for all rainfall events up to and including a 25-year, 24hour rainfall event.

2. Board: The Board of Natural Resources.

3. Buffer: The area of land immediately adjacent to the banks of state waters in its natural state of vegetation, which facilitates the protection of water quality and aquatic habitat.

4. Commission: The State Soil & Water Conservation Commission.

5. Cut: A portion of land surface or area from which earth has been removed or will be removed by excavation; the depth below original ground surface to excavated surface. Also known as excavation.

6. Department: The Department of Natural Resources.

7. Director: The Director of the Environmental Protection Division of the Department of Natural Resources.

8. District: The

(4)

Conservation District.

Soil and Water

GaSWCC (Amended - 2001)

9. Division: The Environmental Protection Division of the Department of Natural Resources.
10. Drainage Structure: A device composed of a virtually nonerodible material such as concrete, steel, plastic or other such material that conveys water from one place to another by intercepting the flow and carrying it to a release point for storm-water management, drainage control, or flood control purposes.
11. Erosion: The process by which land surface is worn away by the action of wind, water, ice or gravity.
12. Erosion and Sedimentation Control Plan: A plan for the control of soil erosion and sedimentation resulting from a land-disturbing activity. Also known as the "plan".
13. Fill: A portion of land surface to which soil or other solid material has been added; the depth above the original ground.
14. Finished Grade: The final elevation and contour of the ground after cutting or filling and conforming to the proposed design.
15. Grading: Altering the shape of ground surfaces to a predetermined condition; this includes stripping, cutting, filling, stockpiling and shaping or any combination thereof and shall include the land in its cut or filled condition.
16. Ground Elevation: The original elevation of the ground surface prior to cutting or filling.
17. Issuing Authority: The governing authority of any county or municipality which has been certified by the Director of the Environmental Protection Division of the Department of Natural Resources as an Issuing Authority, pursuant to the Erosion and Sedimentation Act of 1975, as amended, or the Division in those instances where an application for a permit is submitted to the Division.
18. Land-Disturbing Activity: Any activity which may result in soil erosion from water or wind and the movement of sediments into state waters or onto lands within the state, including, but not limited to, clearing, dredging, grading, excavating, transporting, and filling of land but not including agricultural practices as described in Section III, Paragraph 5.
D-3

19. Metropolitan River Protection Act (MRPA): A state law referenced as O.C.G.A. 12-5-440 et. seq., which addresses environmental and developmental matters in certain metropolitan river corridors and their drainage basins.
20. Natural Ground Surface: The ground surface in its original state before any grading, excavation or filling.
21. Nephelometric Turbidity Units (NTU): Numerical units of measure based upon photometric analytical techniques for measuring the light scattered by finely divided particles of a substance in suspension. This technique is used to estimate the extent of turbidity in water in which colloidally dispersed particles are present.
22. Permit: The authorization necessary to conduct a land-disturbing activity under the provisions of this ordinance.
23. Person: Any individual, partnership, firm, association, joint venture, public or private corporation, trust, estate, commission, board, public or private institution, utility, cooperative, state agency, municipality or other political subdivision of this State, any interstate body or any other legal entity.
24. Project: The entire proposed development project regardless of the size of the area of land to be disturbed.
25. Roadway Drainage Structure: A device such as a bridge, culvert, or ditch, composed of a virtually nonerodible material such as concrete, steel, plastic, or other such material that conveys water under a roadway by intercepting the flow on one side of a traveled way consisting of one or more defined lanes, with or without shoulder areas, and carrying water to a release point on the other side.
26. Sediment: Solid material, both organic and inorganic, that is in suspension, is being transported, or has been moved from its site of origin by air, water, ice, or gravity as a product of erosion.
27. Sedimentation: The process by which eroded material is transported and deposited by the action of water, wind, ice or gravity.

28. Soil and Water Conservation District Approved Plan: An erosion and sedimentation control plan approved in writing by the (5)__ soil and water conservation district.
29. Stabilization: The process of establishing an enduring soil cover of vegetation by the installation of temporary or permanent structures for the purpose of reducing to a minimum the erosion process and the resultant transport of sediment by wind, water, ice or gravity.
30. State Waters: Any and all rivers, streams, creeks, branches, lakes, reservoirs, ponds, drainage systems, springs, wells, and other bodies of surface or subsurface water, natural or artificial, lying within or forming a part of the boundaries of the State which are not entirely confined and retained completely upon the property of a single individual, partnership, or corporation.
31. Structural Erosion and Sedimentation Control Practices: Practices for the stabilization of erodible or sediment-producing areas by utilizing the mechanical properties of matter for the purpose of either changing the surface of the land or storing, regulating or disposing of runoff to prevent excessive sediment loss. Examples of structural erosion and sediment control practices are riprap, sediment basins, dikes, level spreaders, waterways or outlets, diversions, grade stabilization structures, sediment traps and land grading, etc. Such practices can be found in the publication Manual for Erosion and Sediment Control in Georgia.
32. Trout Streams: All streams or portions of streams within the watershed as designated by the Game and Fish Division of the Georgia Department of Natural Resources under the provisions of the Georgia Water Quality Control Act, O.C.G.A. 12-5-20 et. seq. Streams designated as primary trout waters are defined as water supporting a self-sustaining population of rainbow, brown or brook trout. Streams designated as secondary trout waters are those in which there is no evidence of natural trout reproduction, but are capable of supporting trout throughout the year. First order trout waters are streams into which no other streams flow except springs.

D-4

GaSWCC (Amended - 2001)

33. Vegetative Erosion and Sedimentation Control Measures: Measures for the stabilization of erodible or sediment-producing areas by covering the soil with:
A. Permanent seeding, sprigging or planting, producing long-term vegetative cover; or
B. Temporary seeding, producing short-term vegetative cover; or
C. Sodding, covering areas with a turf of perennial sod-forming grass.
Such measures can be found in the publication Manual for Erosion and Sediment Control in Georgia.
34. Watercourse: Any natural or artificial watercourse, stream, river, creek, channel, ditch, canal, conduit, culvert, drain, waterway, gully, ravine, or wash in which water flows either continuously or intermittently and which has a definite channel, bed and banks, and including any area adjacent thereto subject to inundation by reason of overflow or floodwater.
35. Wetlands: Those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas.
SECTION III EXEMPTIONS
This ordinance shall apply to any land-disturbing activity undertaken by any person on any land except for the following:
A. 1. Surface mining, as the same is defined in O.C.G.A. 12-4-72, "Mineral Resources and Caves Act";
2. Granite quarrying and land clearing for such quarrying;
3. Such minor land-disturbing activities as home gardens and individual home landscaping, repairs, maintenance work, and other related activities which result in minor soil erosion;

4. The construction of single-family residences, when such are constructed by or under contract with the owner for his or her own occupancy, or the construction of single-family residences not a part of a platted subdivision, a planned community, or an association of other residential lots consisting of more than two lots and not otherwise exempted under this paragraph; provided, however, that construction of any such residence shall conform to the minimum requirements as set forth in Section IV of this ordinance. For single-family residence construction covered by the provisions of this paragraph, there shall be a buffer zone between the residence and any state waters classified as trout streams pursuant to Article 2 of Chapter 5 of the Georgia Water Quality Control Act. In any such buffer zone, no land-disturbing activity shall be constructed between the residence and the point where vegetation has been wrested by normal stream flow or wave action from the banks of the trout waters. For primary trout waters, the buffer zone shall be at least 50 horizontal feet, and no variance to a smaller buffer shall be granted. For secondary trout waters, the buffer zone shall be at least 50 horizontal feet, but the Director may grant variances to no less than 25 feet. Regardless of whether a trout stream is primary or secondary, for first order trout waters, which are streams into which no other streams flow except for springs, the buffer shall be at least 25 horizontal feet, and no variance to a smaller buffer shall be granted. The minimum requirements of Section IV of this ordinance and the buffer zones provided by this section shall be enforced by the Issuing Authority;
5. Agricultural operations as defined in O.C.G.A. 1-3-3, "definitions", to include raising, harvesting or storing of products of the field or orchard; feeding, breeding or managing livestock or poultry; producing or storing feed for use in the production of livestock, including but not limited to cattle, calves, swine, hogs, goats, sheep, and rabbits or for use in the production of poultry, including but not limited to chickens, hens and turkeys; producing plants, trees, fowl, or animals; the

GaSWCC (Amended - 2001)

D-5

production of aqua culture, horticultural, dairy, livestock, poultry, eggs and apiarian products; farm buildings and farm ponds;
6. Forestry land management practices, including harvesting; provided, however, that when such exempt forestry practices cause or result in land-disturbing or other activities otherwise prohibited in a buffer, as established in paragraphs (15) and (16) of Section IV C. of this ordinance, no other land-disturbing activities, except for normal forest management practices, shall be allowed on the entire property upon which the forestry practices were conducted for a period of three years after completion of such forestry practices;
7. Any project carried out under the technical supervision of the Natural Resources Conservation Service of the United States Department of Agriculture;
8. Any project involving one and one-tenth acres or less; provided, however, that this exemption shall not apply to any land-disturbing activity within 200 feet of the bank of any state waters, and for purposes of this paragraph, "State Waters" excludes channels and drainageways which have water in them only during and immediately after rainfall events and intermittent streams which do not have water in them year-round; provided, however, that any person responsible for a project which involves one and onetenth acres or less, which involves land-disturbing activity, and which is within 200 feet of any such excluded channel or drainageway, must prevent sediment from moving beyond the boundaries of the property on which such project is located and provided, further, that nothing contained herein shall prevent the Issuing Authority from regulating any such project which is not specifically exempted by paragraphs 1, 2, 3, 4, 5, 6, 7, 9 or 10 of this section;
9. Construction or maintenance projects, or both, undertaken or financed in whole or in part, or both, by the Department of Transportation, the Georgia Highway Authority, or the State Tollway Authority; or any road construction or maintenance project, or both, undertaken by any county or municipality; provided, however, that such projects shall
D-6

conform to the minimum requirements set forth in Section IV B. & C. of this ordinance; provided further that construction or maintenance projects of Department of Transportation or State Tollway Authority which disturb five or more contiguous acres of land shall be subject to provisions of Code Section 12-7-7.1; and;
10. Any land-disturbing activities conducted by any electric membership corporation or municipal electrical system or any public utility under the regulatory jurisdiction of the Public Service Commission, provided that any such land-disturbing activity shall conform to the minimum requirements set forth in Section IV B. & C.
B. Where this section requires compliance with the minimum requirements set forth in Section IV B. & C. of this ordinance, Issuing Authorities shall enforce compliance with the minimum requirements as if a permit had been issued and violations shall be subject to the same penalties as violations by permit holders.
SECTION IV MINIMUM REQUIREMENTS FOR EROSION AND SEDIMENTATION CONTROL USING BEST MANAGEMENT PRACTICES
A. GENERAL PROVISIONS
Excessive soil erosion and resulting sedimentation can take place during land-disturbing activities. Therefore, plans for those land-disturbing activities which are not excluded by this ordinance shall contain provisions for application of soil erosion and sedimentation control measures and practices. The provisions shall be incorporated into the erosion and sedimentation control plans. Soil erosion and sedimentation control measures and practices shall conform to the minimum requirements of Section IV B. & C. of this ordinance. The application of measures and practices shall apply to all features of the site, including street and utility installations, drainage facilities and other temporary and permanent improvements. Measures shall be installed to prevent or control erosion and sedimentation pollution during all stages of any land-disturbing activity.
GaSWCC (Amended - 2001)

B. MINIMUM REQUIREMENTS/BMP's
1. Best management practices as set forth in Section IV B. & C. of this ordinance shall be required for all land-disturbing activities. Proper design, installation, and maintenance of best management practices shall constitute a complete defense to any action by the Director or to any other allegation of noncompliance with paragraph (2) of this subsection or any substantially similar terms contained in a permit for the discharge of stormwater issued pursuant to subsection (f) of Code Section 12-5-30, the "Georgia Water Quality Control Act". As used in this subsection the terms "proper design" and "properly designed" mean designed to control soil erosion and sedimentation for all rainfall events up to and including a 25-year, 24-hour rainfall event.
2. A discharge of stormwater runoff from disturbed areas where best management practices have not been properly designed, installed, and maintained shall constitute a separate violation of any land-disturbing permit issued by a local Issuing Authority or by the Division or of any general permit for construction activities issued by the Division pursuant to subsection (f) of Code Section 12-5-30, the "Georgia Water Quality Control Act", for each day on which such discharge results in the turbidity of receiving waters being increased by more than 25 nephelometric turbidity units for waters supporting warm water fisheries or by more than ten nephelometric turbidity units for waters classified as trout waters. The turbidity of the receiving waters shall be measured in accordance with guidelines to be issued by the Director.
3. Failure to properly design, install, or maintain best management practices shall constitute a violation of any land-disturbing permit issued by a local Issuing Authority or by the Division or any general permit for construction activities issued by the Division pursuant to subsection (ft of Code Section 1 2-5-30, the "Georgia Water Quality Control Act", for each day on which such failure occurs.
4. The Director may require, in accordance with regulations adopted by the Board, reason-
GaSWCC (Amended - 2001)

able and prudent monitoring of the turbidity level of receiving waters into which discharges from land-disturbing activities occur.
C. The rules and regulations, ordinances, or resolutions adopted pursuant to this chapter for the purpose of governing landdisturbing activities shall require, as a minimum, best management practices, including sound conservation and engineering practices to prevent and minimize erosion and resultant sedimentation, which are consistent with, and no less stringent than, those practices contained in the Manual for Erosion and Sediment Control in Georgia published by the Georgia Soil and Water Conservation Commission as of January 1 of the year in which the land-disturbing activity was permitted, as well as the following:
1. Stripping of vegetation, regrading and other development activities shall be conducted in a manner so as to minimize erosion;
2. Cut-fill operations must be kept to a minimum;
3. Development plans must conform to topography and soil type so as to create the lowest practical erosion potential;
4. Whenever feasible, natural vegetation shall be retained, protected and supplemented;
5. The disturbed area and the duration of exposure to erosive elements shall be kept to a practicable minimum;
6. Disturbed soil shall be stabilized as quickly as practicable;
7. Temporary vegetation or mulching shall be employed to protect exposed critical areas during development;
8. Permanent vegetation and structural erosion control practices shall be installed as soon as practicable;
9. To the extent necessary, sediment in run-off water must be trapped by the use of debris basins, sediment basins, silt traps, or similar measures until the disturbed area is sta-
D-7

bilized. As used in this paragraph, a disturbed area is stabilized when it is brought to a condition of continuous compliance with the requirements of O.C.G.A. 12-7-1 et. seq.;
10. Adequate provisions must be provided to minimize damage from surface water to the cut face of excavations or the sloping of fills;
11. Cuts and fills may not endanger adjoining property;
12. Fills may not encroach upon natural watercourses or constructed channels in a manner so as to adversely affect other property owners;
13. Grading equipment must cross flowing streams by means of bridges or culverts except when such methods are not feasible, provided, in any case, that such crossings are kept to a minimum;
14. Land-disturbing activity plans for erosion and sedimentation control shall include provisions for treatment or control of any source of sediments and adequate sedimentation control facilities to retain sediments on-site or preclude sedimentation of adjacent waters beyond the levels specified in Section IV B. 2. of this ordinance;
15. Except as provided in paragraph (16) of this subsection, there is established a 25 foot buffer along the banks of all state waters, as measured horizontally from the point where vegetation has been wrested by normal stream flow or wave action, except where the Director determines to allow a variance that is at least as protective of natural resources and the environment, where otherwise allowed by the Director pursuant to O.C.G.A. 12-2-8, or where a drainage structure or a roadway drainage structure must be constructed, provided that adequate erosion control measures are incorporated in the project plans and specifications, and are implemented; provided, however, the buffers of at least 25 feet established pursuant to part 6 of Article 5, Chapter 5 of Title 12, the "Georgia Water Quality Control Act", shall remain in force unless a variance is granted by the Director as provided in this paragraph. The following requirements shall apply to any such buffer:
D-8

No land-disturbing activities shall be conducted within a buffer and a buffer shall remain in its natural, undisturbed state of vegetation until all land-disturbing activities on the construction site are completed. Once the final stabilization of the site is achieved, a buffer may be thinned or trimmed of vegetation as long as a protective vegetative cover remains to protect water quality and aquatic habitat and a natural canopy is left in sufficient quantity to keep shade on the stream bed; provided, however, that any person constructing a single-family residence, when such residence is constructed by or under contract with the owner for his or her own occupancy, may thin or trim vegetation in a buffer at any time as long as protective vegetative cover remains to protect water quality and aquatic habitat and a natural canopy is left in sufficient quantity to keep shade on the stream bed; and
16. There is established a 50 foot buffer as measured horizontally from the point where vegetation has been wrested by normal stream flow or wave action, along the banks of any state waters classified as "trout streams" pursuant to Article 2 of Chapter 5 of Title 12, the "Georgia Water Quality Control Act", except where a roadway drainage structure must be constructed ; provided, however, that small springs and streams classified as trout streams which discharge an average annual flow of 25 gallons per minute or less shall have a 25 foot buffer or they may be piped, at the discretion of the landowner, pursuant to the terms of a rule providing for a general variance promulgated by the Board, so long as any such pipe stops short of the downstream landowner's property and the landowner complies with the buffer requirement for any adjacent trout streams. The Director may grant a variance from such buffer to allow land-disturbing activity, provided that adequate erosion control measures are incorporated in the project plans and specifications and are implemented. The following requirements shall apply to such buffer:
No land-disturbing activities shall be conducted within a buffer and a buffer shall remain in its natural, undisturbed, state
GaSWCC (Amended - 2001)

of vegetation until all land-disturbing activities on the construction site are completed. Once the final stabilization of the site is achieved, a buffer may be thinned or trimmed of vegetation as long as a protective vegetative cover remains to protect water quality and aquatic habitat and a natural canopy is left in sufficient quantity to keep shade on the stream bed: provided, however, that any person constructing a single-family residence, when such residence is constructed by or under contract with the owner for his or her own occupancy, may thin or trim vegetation in a buffer at any time as long as protective vegetative cover remains to protect water quality and aquatic habitat and a natural canopy is left in sufficient quantity to keep shade on the stream bed; and
D. Nothing contained in this chapter shall prevent an Issuing Authority from adopting rules and regulations, ordinances, or resolutions which contain requirements that exceed the minimum requirements in Section IV B. & C. of this ordinance.
E. The fact that land-disturbing activity for which a permit has been issued results in injury to the property of another shall neither constitute proof of nor create a presumption of a violation of the standards provided for in this ordinance or the terms of the permit.
SECTION V APPLICATION/PERMIT PROCESS
A. GENERAL
The property owner, developer and designated planners and engineers shall review the general development plans and detailed plans of the Issuing Authority that affect the tract to be developed and the area surrounding it. They shall review the zoning ordinance, stormwater management ordinance, subdivision ordinance, flood damage prevention ordinance, this ordinance, and other ordinances which regulate the development of land within the jurisdictional boundaries of the Issuing Authority. However, the property owner is the only party who may obtain a permit.

B. APPLICATION REQUIREMENTS

1. No person shall conduct any land-disturb-

ing activity within the jurisdictional bound-

aries of the

(6)

without first

obtaining a permit from the

(7)

to

perform such activity.

2. The application for a permit shall be sub-

mitted to the

(8)

and must include

the applicant's erosion and sedimentation

control plan with supporting data, as nec-

essary. Said plans shall include, as a mini-

mum, the data specified in Section V C. of

this ordinance. Soil erosion and sedimenta-

tion control plans shall conform to the provi-

sions of Section IV B. & C. of this ordinance.

Applications for a permit will not be accepted

unless accompanied by (9) copies

of the applicant's soil erosion and sedimen-

tation control plans.

3. A fee, in the amount of $ (10)

shall

be charged for each acre or fraction thereof

in the project area.

4. Immediately upon receipt of an application and plan for a permit, the Issuing Authority shall refer the application and plan to the District for its review and approval or disapproval concerning the adequacy of the erosion and sedimentation control plan. The results of the District review shall be forwarded to the Issuing Authority. No permit will be issued unless the plan has been approved by the District, and any variances required by Section IV C. 15. & 16. and bonding, if required as per Section V B.5. (b), have been obtained. Such review will not be required if the Issuing Authority and the District have entered into an agreement which allows the Issuing Authority to conduct such review and approval of the plan without referring the application and plan to the District.

5. (a) If a permit applicant has had two or more violations of previous permits, this ordinance section, or the Erosion and Sedimentation Act, as amended, within three years prior to the date of filing of the application under consideration, the Issuing Authority may deny the permit application.

GaSWCC (Amended - 2001)

D-9

(b) The Issuing Authority may require the permit applicant to post a bond in the form of government security, cash, irrevocable letter of credit, or any combination thereof up to, but not exceeding, $3,000.00 per acre or fraction thereof of the proposed land-disturbing activity, prior to issuing the permit. If the applicant does not comply with this ordinance or with the conditions of the permit after issuance, the Issuing Authority may call the bond or any part thereof to be forfeited and may use the proceeds to hire a contractor to stabilize the site of the land-disturbing activity and bring it into compliance. These provisions shall not apply unless there is in effect an ordinance or statute specifically providing for hearing and judicial review of any determination or order of the Issuing Authority with respect to alleged permit violations.
C. PLAN REQUIREMENTS
1. Plans must be prepared to meet the minimum requirements as contained in Section IV B. & C. of this ordinance. Conformance with the minimum requirements may be attained through the use of design criteria in the current issue of the Manual for Erosion and Sediment Control in Georgia, published by the State Soil and Water Conservation Commission as a guide; or through the use of more stringent, alternate design criteria which conform to sound conservation and engineering practices. The Manual for Erosion and Sediment Control in Georgia is hereby incorporated by reference into this ordinance. The plan for the land-disturbing activity shall consider the interrelationship of the soil types, geological and hydrological characteristics, topography, watershed, vegetation, proposed permanent structures including roadways, constructed waterways, sediment control and storm water management facilities, local ordinances and State laws.
2. Data Required for Site Plan
(a) Narrative or notes, and other information: Notes or narrative to be located

on the site plan in general notes or in erosion and sediment control notes.
(b) Description of existing land use at project site and description of proposed project.
(c) Name, address, and phone number of the property owner.
(d) Name and phone number of 24-hour local contact who is responsible for erosion and sedimentation controls.
(e) Size of project, or phase under construction, in acres.
(f) Activity schedule showing anticipated starting and completion dates for the project. Include the statement in bold letters, that "the installation of erosion and sedimentation control measures and practices shall occur prior to or concurrent with land-disturbing activities."
(g) Stormwater and sedimentation management systems-storage capacity, hydrologic study, and calculations, including off-site drainage areas.
(h) Vegetative plan for all temporary and permanent vegetative measures, including species, planting dates, and seeding, fertilizer, lime, and mulching rates. The vegetative plan should show options for year-round seeding.
(i) Detail drawings for all structural practices. Specifications may follow guidelines set forth in the Manual for Erosion and Sediment Control in Georgia.
(j) Maintenance statement - "Erosion and sedimentation control measures will be maintained at all times. Additional erosion and sedimentation control measures and practices will be installed if deemed necessary by onsite inspection."

D-10

GaSWCC (Amended - 2001)

3. Maps, drawings, and supportive computations shall bear the signature/seal of a registered or certified professional in engineering, architecture, landscape architecture, land surveying, or erosion and sedimentation control. The certified plans shall contain:
(a) Graphic scale and north point or arrow indicating magnetic north.
(b) Vicinity maps showing location of project and existing streets.
(c) Boundary line survey.
(d) Delineation of disturbed areas within project boundary.
(e) Existing and planned contours, with an interval in accordance with the following:

Map Scale
1 inch = 100 ft. or larger scale

Ground Slope
Flat 0-2% Rolling 2-8% Steep 8% +

Contour Interval, ft.
0.5 or 1 1 or 2 2, 5 or 10

(f) Adjacent areas and features areas such as streams, lakes, residential areas, etc. which might be affected should be indicated on the plan.
(g) Proposed structures or additions to existing structures and paved areas.
(h) Delineate the 25-foot horizontal buffer adjacent to state waters and the specified width in MRPA areas.
(i) Delineate the specified horizontal buffer along designated trout streams, where applicable.
(j) Location of erosion and sedimentation control measures and practices using coding symbols from the Manual for Erosion and Sediment Control in Georgia, Chapter 6.

4. Maintenance of all soil erosion and sedimentation control practices, whether temporary or permanent, shall be at all times the responsibility of the property owner.

D. PERMITS

1. Permits shall be issued or denied as soon as practicable but in any event not later than forty-five (45) days after receipt by the Issuing Authority of a completed application, providing variances and bonding are obtained, where necessary.

2. No permit shall be issued by the Issuing Authority unless the erosion and sedimentation control plan has been approved by the District and the Issuing Authority has affirmatively determined that the plan is in compliance with this ordinance, any variances required by Section IV C. 15. & 16. are obtained, bonding requirements, if necessary, as per Section V B. 5. (b) are met and all ordinances and rules and regulations in effect within the jurisdictional boundaries of the Issuing Authority are met. If the permit is denied, the reason for denial shall be furnished to the applicant.

3. If the tract is to be developed in phases, then a separate permit shall be required for each phase.

4. The permit may be suspended, revoked, or modified by the Issuing Authority, as to all or any portion of the land affected by the plan, upon finding that the holder or his successor in the title is not in compliance with the approved erosion and sedimentation control plan or that the holder or his successor in title is in violation of this ordinance. A holder of a permit shall notify any successor in title to him as to all or any portion of the land affected by the approved plan of the conditions contained in the permit.

5. No permit shall be issued unless the appli-

cant provides a statement by the

(11)

5 certifying that all ad valorem taxes levied

against the property and due and owing have

been paid.

GaSWCC (Amended - 2001)

D-11

SECTION VI INSPECTION AND ENFORCEMENT

A. The

(12)

will periodically

inspect the sites of land-disturbing activi-

ties for which permits have been issued to

determine if the activities are being con-

ducted in accordance with the plan and if

the measures required in the plan are

effective in controlling erosion and sedi-

mentation. If, through inspection, it is

deemed that a person engaged in land-

disturbing activities as defined herein has

failed to comply with the approved plan,

with permit conditions, or with the provi-

sions of this ordinance, a written notice to

comply shall be served upon that person.

The notice shall set forth the measures

necessary to achieve compliance and

shall state the time within which such

measures must be completed. If the

person engaged in the land-disturbing

activity fails to comply within the time

specified, he shall be deemed in violation

of this ordinance.

B. The

(13)

shall have the power

to conduct such investigations as it may

reasonably deem necessary to carry out

duties as prescribed in this ordinance, and

for this purpose to enter at reasonable

times upon any property, public or private,

for the purpose of investigation and in-

specting the sites of land-disturbing

activities.

C. No person shall refuse entry or access to any authorized representative or agent of the Issuing Authority, the Commission, the District, or Division who requests entry for the purposes of inspection, and who presents appropriate credentials, nor shall any person obstruct, hamper or interfere with any such representative while in the process of carrying out his official duties.

D. The Districts or the Commission or both shall periodically review the actions of counties and municipalities which have been certified as Issuing Authorities pursuant to O.C.G.A. 12-7-8 (a). The Districts or the Commission or both may provide technical assistance to any county or municipality for the purpose of improv-

D-12

ing the effectiveness of the county's or municipality's erosion and sedimentation control program. The Districts or the Commission shall notify the Division and request investigation by the Division if any deficient or ineffective local program is found.
E. The Division may periodically review the actions of counties and municipalities which have been certified as Issuing Authorities pursuant to Code Section 12-78 (a). Such review may include, but shall not be limited to, review of the administration and enforcement of a governing authority's ordinance and review of conformance with an agreement, if any, between the district and the governing authority. If such review indicates that the governing authority of any county or municipality certified pursuant to O.C.C.A. 12-7-8 (a) has not administered or enforced its ordinances or has not conducted the program in accordance with any agreement entered into pursuant to O.C.G.A. 12-7-7 (d), the Division shall notify the governing authority of the county or municipality in writing. The governing authority of any county or municipality so notified shall have 30 days within which to take the necessary corrective action to retain certification as an Issuing Authority. If the county or municipality does not take necessary corrective action within 30 days after notification by the division, the division may revoke the certification of the county or municipality as an Issuing Authority.
SECTION VII PENALTIES AND INCENTIVES
A. FAILURE TO OBTAIN A PERMIT FOR LAND-DISTURBING ACTIVITY
If any person commences any land-disturbing activity requiring a land-disturbing permit as prescribed in this ordinance without first obtaining said permit, the person shall be subject to revocation of his business license, work permit or other authorization for the conduct of a business and associated work activities within the jurisdictional boundaries of the Issuing Authority.
GaSWCC (Amended - 2001)

B. STOP-WORK ORDERS
1. For the first and second violations of the provisions of this ordinance, the Director or the Issuing Authority shall issue a written warning to the violator. The violator shall have five days to correct the violation. If the violation is not corrected within five days, the Director or the Issuing Authority shall issue a stop-work order requiring that land-disturbing activities be stopped until necessary corrective action or mitigation has occurred; provided, however, that, if the violation presents an imminent threat to public health or waters of the state or if the land-disturbing activities are conducted without obtaining the necessary permit, the Director or Issuing Authority shall issue an immediate stopwork order in lieu of a warning;
2. For a third and each subsequent violation, the Director or Issuing Authority shall issue an immediate stop-work order; and;
3. All stop-work orders shall be effective immediately upon issuance and shall be in effect until the necessary corrective action or mitigation has occurred.
C. BOND FORFEITURE
If, through inspection, it is determined that a person engaged in land-disturbing activities has failed to comply with the approved plan, a written notice to comply shall be served upon that person. The notice shall set forth the measures necessary to achieve compliance with the plan and shall state the time within which such measures must be completed. If the person engaged in the land-disturbing activity fails to comply within the time specified, he shall be deemed in violation of this ordinance and, in addition to other penalties, shall be deemed to have forfeited his performance bond, if required to post one under the provisions of Section V B. 5. (b). The Issuing Authority may call the bond or any part thereof to be forfeited and may use the proceeds to hire a contractor to stabilize the site of the land-disturbing activity and bring it into compliance.

D. MONETARY PENALTIES
1. Except as provided in paragraph (2) of this subsection, any person who violates any provisions of this ordinance, the rules and regulations adopted pursuant hereto, or any permit condition or limitation established pursuant to this ordinance or who negligently or intentionally fails or refuses to comply with any final or emergency order of the Director issued as provided in this ordinance shall be liable for a civil penalty not to exceed $2,500.00 per day. For the purpose of enforcing the provisions of this ordinance, notwithstanding any provisions in any City charter to the contrary, municipal courts shall be authorized to impose penalty not to exceed $2,500.00 for each violation. Notwithstanding any limitation of law as to penalties which can be assessed for violations of county ordinances, any magistrate court or any other court of competent jurisdiction trying cases brought as violations of this ordinance under county ordinances approved under this ordinance shall be authorized to impose penalties for such violations not to exceed $2,500.00 for each violation. Each day during which violation or failure or refusal to comply continues shall be a separate violation.
2. The following penalties shall apply to landdisturbing activities performed in violation of any provision of this ordinance, any rules and regulations adopted pursuant hereto, or any permit condition or limitation established pursuant to this ordinance;
(A) There shall be a minimum penalty of $250.00 per day for each violation involving the construction of a singlefamily dwelling by or under contract with the owner for his or her own occupancy; and;
(B) There shall be a minimum penalty of $1,000.00 per day for each violation involving land-disturbing activities other than as provided in subsection (A) of this paragraph.

GaSWCC (Amended - 2001)

D-13

SECTION VIII ADMINISTRATIVE APPEAL JUDICIAL REVIEW

A. ADMINISTRATIVE REMEDIES

The suspension, revocation, modification or

grant with condition of a permit by the Issu-

ing Authority upon finding that the holder is

not in compliance with the approved erosion

and sediment control plan; or that the holder

is in violation of permit conditions; or that

the holder is in violation of any ordinance;

shall entitle the person submitting the plan

or holding the permit to a hearing before the

___ _ (14) __ __ within

(15)

days after receipt by the Issuing Authority

of written notice of appeal.

B. JUDICIAL REVIEW

Any person, aggrieved by a decision or order of the Issuing Authority, after exhausting his administrative remedies, shall have the right to appeal denovo to the Superior Court of (16) .

SECTION IX EFFECTIVITY, VALIDITY AND LIABILITY

A. EFFECTIVITY

This ordinance shall become effective on

the (17) day of

(18)

, 20 (19) .

B. VALIDITY

If any section, paragraph, clause, phrase, or provision of this ordinance shall be adjudged invalid or held unconstitutional, such decisions shall not effect the remaining portions of this ordinance.

C. LIABILITY

1. Neither the approval of a plan under the provisions of this ordinance, nor the compliance with provisions of this ordinance shall relieve any person from the responsibility for damage to any person or property otherwise imposed by law nor impose any liability upon the Issuing Authority or District for damage to any person or property.

2. The fact that a land-disturbing activity for which a permit has been issued results in injury to the property of another shall neither constitute proof of nor create a presumption of a violation of the standards provided for in this ordinance or the terms of the permit.

3. No provision of this ordinance shall permit any persons to violate the Georgia Erosion and Sedimentation Act of 1975, the Georgia Water Quality Control Act or the rules and regulations promulgated and approved thereunder or pollute any Waters of the State as defined thereby.

ATTEST:

Signature

(20)___________________

Signature

(21)___________________

D-14

GaSWCC (Amended - 2001)

CONVERSION FACTORS

TO CONVERT:

MULTIPLY BY:

TO OBTAIN:

acres . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . acres . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . acres . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . acres . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . acres . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . acres . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . acre-feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . acre-feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . centimeters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cubic feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cubic feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cubic feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cubic feet/min. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cubic feet/sec. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cubic meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cubic meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cubic meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cubic yards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cubic yards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . feet of water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . gallons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . gallons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . gallons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . gallons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . gallons of water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . gallons/min. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . gallons/min. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . grams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . hectares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . hectares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . inches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kilograms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kilograms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kilometers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kilometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kilometers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . liters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . miles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . miles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . miles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . million gals/day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . rods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . square feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . square feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . square meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . square meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . square meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . square miles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . square miles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . square miles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . square yards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . square yards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . square yards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . square yards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . tons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . yards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . yards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.60 x 102 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.047 x 10-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.35 x 104 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.047 x 103 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.562 x 10-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.840 x 103 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.356 x 104 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.259 x 105 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.937 x 10-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.832 x 10-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.48052 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.832 x 101 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.247 x 10-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.46317 x 10-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.531 x 101 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.308 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.642 x 102 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.02 x 102 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.646 x 102 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.048 x 101 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.048 x 10-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.894 x 10-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.335 x 10-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.337 x 10-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.785 x 10-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.951 x 10-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.785 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.337 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.228 x 10-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.308 x 10-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.205 x 10-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.471 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.076 x 105 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.540 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2046 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.102 x 10-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.281 x 103 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.214 x 10-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0936 x 103 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.642 x 10-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.281 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.094 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.280 x 103 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.609 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.760 x 103 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.54723 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.65 x 101 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.296 x 10-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.29 x 10-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.076 x 101 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.861 x 10-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.196 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.40 x 102 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.590 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.098 x 106 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.066 x 10-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.361 x 10-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.228 x 10-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.0718 x 102 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.144 x 10-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.682 x 10-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

sq. rods hectares sq. ft. sq. meters sq. miles sq. yards cu. feet gallons inches cu. meters gallons liters gallons/sec. million gals/day cu. ft. cu. yards gallons gallons liters centimeters meters miles pounds/sq. in. cu. feet cu. meters cu. yards liters pounds of water cu. ft/sec. liters/sec. pounds acres sq. feet centimeters pounds tons feet miles yards gallons feet yards feet kilometers yards cu. ft/sec. feet acres sq. meters sq. ft. sq. miles sq. yards acres sq. kms. sq. yards acres sq. ft. sq. meters sq. miles kilograms meters miles

GaSWCC (Amended - 2001)

E-1

E-2

GaSWCC

APPENDIX F
GLOSSARY
The list of terms that follows is representative of those used by soil scientists, engineers, developers, conservationist planners, etc. The terms are not necessarily used in the text, nonetheless they are in common use in conservation matters.
AASHTO CLASSIFICATION (soil engineering) The official classification of soil materials and soil aggregate mixtures for highway construction used by the American Association of State Highway Transportation Officials.
ACID SOIL - A soil with a preponderance of hydrogen ions, and probably of aluminum in proportion to hydroxyl ions. Specifically, soil with a pH value less than 7.0. For most practical purposes, a soil with a pH less than 6.6, the values obtained vary greatly with the method used consequently there is no unanimous agreement on what constitutes an acid soil.The term is usually applied to the surface layer or to the root zone unless specified otherwise.
ACRE-FOOT - The volume of water that will cover 1 acre to a depth of 1 foot.
AGGRADATION - The process of building up a surface by deposition. This is a long-term or geologic trend in sedimentation.
ALKALINE SOIL - A soil that has a pH greater than 7.0, particularly above 7.3, throughout most or all of the root zone, although the term is commonly applied to only the surface layer or horizon of a soil.
ALLUVIAL - Pertaining to material that is transported and deposited by running water.
ALLUVIAL LAND - Areas of unconsolidated alluvium, generally stratified and varying widely in texture, recently deposited by streams, and subject to frequent flooding. A miscellaneous land type.
ALLUVIAL SOILS - An axonal great soil group of soils, developed from transported and recently deposited material (alluvium) characterized by a weak modification (or none) of the original material by soil forming processes.
ALLUVIUM - A general term for all detrital material deposited or in transit by streams, including gravel, sand, silt, clay, and all variations and mixtures of these. Unless otherwise noted, alluvium is unconsolidated.
ANGLE OF REPOSE - Angle between the horizontal and the maximum slope that a soil assumes through natural processes.
GaSWCC (Amended - 2000)

ANTECEDENT SOIL WATER - Degree of wetness of a soil prior to irrigation or at the beginning of a runoff period, expressed as an index or as total inches soil water.
ANTI-SEEP COLLAR - A device constructed around a pipe or other conduit and placed through a dam, levee, or dike for the purpose of reducing seepage losses and piping failures.
ANTI-VORTEX DEVICE - A facility placed at the entrance to a pipe conduit structure such as a drop inlet spillway or hood inlet spillway to prevent air from entering the structure when the pipe is flowing full.
APRON (soil engineering) - A floor or lining to protect a surface from erosion. An example is the pavement below chutes, spillways, or at the toes of dams.
AUXILIARY SPILLWAY - A dam spillway built to carry runoff in excess of that carried by the principal spillway. See Emergency Spillway.
BACKFILL - The material used to refill a ditch or other excavation, or the process of doing so.
BEDROCK - The solid rock underlying soils and the regolith in depths ranging from zero (where exposed by erosion) to several hundred feet.
BEDLOAD - The sediment that moves by sliding, rolling, or bounding on or very near the streambed; sediment moved mainly by tractive or gravitational forces or both but at velocities less than the surrounding flow.
BEST MANAGEMENT PRACTICES (BMP) - A collection of structural practices and vegetative measures which, when properly designed, installed and maintained, will provide effective erosion and sedimentation control for all rainfall events up to and including a 25year, 24-hour rainfall event.
BLINDING MATERIAL - Material placed on top and around a closed drain to improve the flow of water to the drain and to prevent displacement during back-filling of the trench.
BLIND INLET - Inlet to a drain in which entrance of water is by percolation rather than open flow channels.
BORROW AREA - A source of earth fill material used in the construction of embankments or other earthfill structures.
BOTTOM LANDS - A term often used to define lowlands adjacent to streams.
F-1

BOX-CUT - The initial cut driven in a property where no open side exists, resulting in a highwall on both sides at the cut.
BRUSH MATTING
(1) A matting of branches placed on badly eroded land to conserve moisture and reduce erosion while trees or other vegetative covers are being established.
(2) A matting of mesh wire and brush used to retard streambank erosion.
CHANNEL - A natural stream that conveys water; a ditch or channel excavated for the flow of water. See Watercourse.
CHANNEL IMPROVEMENT - The improvement of the flow characteristics of a channel by clearing, excavation, realignment, lining, or other means in order to increase its capacity. Sometimes used to connote channel stabilization.
CHANNEL SLOPE - Natural or excavated sides (banks) of a watercourse.
CHANNEL STABILIZATION - Erosion prevention and stabilization of velocity distribution in a channel using jetties, drops, revetments, vegetation, and other measures.
CHANNEL STORAGE - Water temporarily stored in channels while enroute to an outlet.
COLLOID - In soil, organic or inorganic matter having very small particle size and a correspondingly large surface area per unit of mass. Most colloidal particles are too small to be seen with the ordinary compound microscope.
COMPACTION - In soil engineering, the process by which the silt grains are rearranged to decrease void space and bring them into closer contact with one another, thereby increasing the weight of solid material per cubic foot.
CONDUIT - Any channel intended for the conveyance of water, whether open or closed.
CONSERVATION - The protection, improvement, and use of natural resources according to principles that will assure their highest economic or social benefits.
CONSERVATION DISTRICT - A public organization created under state enabling law as a special purpose district to develop and carry out a program of soil, water, and related resource conservation, use, and development within its boundaries, usually a subdivision of state government with a local governing body. Often called a soil conservation district or a soil and water conservation district.

CONTOUR
(1) An imaginary line on the surface of the earth connecting points of the same elevation.
(2) A line drawn on a map connecting points of the same elevation.
COVER CROP - A close-growing crop grown primarily for the purpose of protecting and improving soil between periods of permanent vegetation.
CRADLE - A device, usually concrete, used to support a pipe conduit or barrel.
CREEP (SOIL) - Slow mass movement of soil and soil material down relatively steep slopes, primarily under the influence of gravity but facilitated by saturation with water and by alternate freezing and thawing.
CRITICAL AREA - A severely eroded sediment producing area that requires special management to establish and maintain vegetation to stabilize soil conditions.
CUT - A portion of land surface or area from which earth has been removed or will be removed by excavation; the depth below the original ground surface to the excavated surface. Syn. Excavation.
CUT-AND-FILL - Process of earth moving by excavating part of an area and using the excavated material for adjacent embankments or fill areas.
CUTOFF - A wall, collar or other structure, such as a trench, filled with relatively impervious material intended to reduce seepage of water through porous strata.
DAM - A barrier to confine or raise water for storage or diversion, to create a hydraulic head, to prevent gully erosion, or for retention or soil, rock, or other debris.
DEBRIS - The loose material arising from the disintegration of rocks and vegetative material; transportable by streams, ice or floods.
DEBRIS DAM - A barrier built across a stream channel to retain rock, sand, gravel, silt, or other material.
DEBRIS GUARD - A screen or grate at the intake of a channel, drainage, or pump structure for the purpose of stopping debris.
DEGRADATION - To wear down by erosion, especially through stream action.
DESIGN HIGHWATER - The elevation of the water surface as determined by the flow conditions of the design floods.
DESIGN LIFE - The period of time for which a facility is expected to perform its intended function.

F-2

GaSWCC (Amended - 2000)

DESILTING AREA - An area of grass, shrubs, or other vegetation used for inducing deposition of silt and other debris from flowing water; located above a stock tank, pond, field, or other area needing protection from sediment accumulation. See Filter Strip.
DETENTION DAM - A dam constructed for the purpose of temporary storage of streamflow or surface runoff and for releasing the stored water at controlled rates.
DIKE (engineering) - An embankment to confine or control water, especially one built along the banks of a river to prevent overflow of lowlands; a levee. (geology) A tabular body of igneous rock that cuts across the structure of adjacent rocks or cuts massive rocks.
DISCHARGE (hydraulics) - Rate of flow, specifically fluid flow; a volume of fluid passing a point per unit time, commonly expressed as cubic feet per second, million gallons per day, gallons per minute, or cubic meters per second.
DISCHARGE COEFFICIENT (hydraulics) - The ratio of actual rate of flow to the theoretical rate of flow through orifices, weirs, or other hydraulic structures.
DISCHARGE FORMULA (hydraulics) - A formula to calculate rate of flow of fluid in a conduit or through an opening. For steady flow discharge, Q = AV, wherein Q is rate of flow, A is cross-sectional area and V is mean velocity. Common units are cubic feet per second, square feet, and feet per second, respectively. To calculate the mean velocity, V for uniform flow in pipes or open channels see Manning's Formula.
DISPERSION, SOIL - The breaking down of soil aggregates into individual particles, resulting in single-grain structure. Ease of dispersion is an important factor influencing the erodibility of soils. Generally speaking, the more easily dispersed the soil, the more erodible it is.
DIVERSION - A channel with or without a supporting ridge on the lower side constructed across the top or bottom of a slope for the purpose of intercepting surface runoff.
DIVERISION DAM - A barrier built to divert part or all of the water from a stream into a different course.
DRAIN
(1) A buried pipe or other conduit (closed drain).
(2) A ditch (open drain) for carrying off surplus surface water of groundwater.
(3) To provide channels, such as open ditches or closed drains, so that excess water can be removed by surface flow or by internal flow.
(4) To lose water (from the soil) by percolation.

DRAINAGE
(1) The removal of excess surface water or ground-water from land by means of surface or subsurface drains.
(2) Soil characteristics that affect natural drainage.
DRAINAGE, SOIL - As a natural condition of the soil, soil drainage refers to the frequency and duration of periods when the soil is free of saturation; for example, in well-drained soils the water is removed readily but not rapidly; in poorly drained soils the root zone is waterlogged for long periods unless artificially drained, and the roots of ordinary crop plants cannot get enough oxygen: in excessively drained soils the water is removed so completely that most crop plants suffer from lack of water. Strictly speaking, excessively drained soils are a result of excessive runoff due to steep slopes or low available water holding capacity due to small amounts of silt and clay in the soil material. The following classes are used to describe soil drainage:
Well drained - excess water drains away rapidly and no mottling occurs within 36 inches of the surface.
Moderately well drained - water is removed from the soil somewhat slowly, resulting in small but significant periods of wetness. Mottling occurs between 8 and 18 inches.
Somewhat poorly drained - water is removed from the soil slowly enough to keep it wet for significant periods but not all of the time. Mottling occurs between 0 to 18 inches.
Poorly drained - water is removed so slowly that the soil is wet for a large part of the time. Mottling occurs between 0 to 8 inches.
Very poorly drained - water is removed so slowly that the water table remains at or near the surface for the greater part of the time. There may also be periods of surface ponding. The soil has a black to gray surface layer with mottles up to the surface.
DRAWDOWN - Lowering of the water surface (in open channel flow), water table, or piezometric surface (in groundwater flow) resulting from a withdrawal of water.
DROP-INLET SPILLWAY - An overfall structure in which the water drops through a vertical riser connected to a discharge conduit.
DROP SPILLWAY - An overfall structure in which the water drops over a vertical wall onto an apron at a lower elevation.

GaSWCC (Amended - 2000)

F-3

DROP STRUCTURE - A structure for dropping water to a lower level and dissipating its surplus energy; a fall. A drop may be vertical or inclined.
EARTH DAM - Dam constructed of compacted soil material.
EMBANKMENT - A man-made deposit of soil, rock, or other material used to form an impoundment.
EMERGENCY SPILLWAY - A spillway used to carry runoff exceeding a given design flood. Syn. Auxiliary Spillway.
ENERGY DISSIPATOR - A device used to reduce the energy of flowing water.
ERODIBLE (geology and soils) - Susceptible to erosion.
EROSION
(1) The wearing away of the land surface by running water, wind, ice or other geological agents, including such processes as gravitational creep.
(2) Detachment and movement of soil or rock fragments by water, wind, ice, or gravity. The following terms are used to describe different types of water erosion:
ACCELERATED EROSION - Erosion much more rapid than normal, or geologic erosion, primarily as a result of the influence of the activities of man, or in some cases, of other animals or natural catastrophes that expose base surfaces, for example, fires.
GEOLOGIC EROSION - The normal or natural erosion caused by geological processes acting over long geologic periods and resulting in the wearing away of mountains, the building up of floodplains, coastal plains, etc. See Natural Erosion.
GULLY EROSION - The erosion process whereby water accumulates in narrow channels and, over short periods, removes the soil from this narrow area to considerable depths, ranging from 1 to 2 feet to as much as 75 to 100 feet.
NATURAL EROSION - Wearing away of the earth's surface by water, ice, or other natural agents under natural environmental conditions of climate, vegetation, etc., undisturbed by man. See Geological Erosion.
NORMAL EROSION - The gradual erosion of land used by man which does not greatly exceed natural erosion. See Natural Erosion.
RILL EROSION - An erosion process in which numerous small channels only several inches deep are formed; occurs mainly on recently disturbed and exposed soils. See Rill.

SHEET EROSION - The removal of fairly uniform layer of soil from the land surface by runoff water.
SPLASH EROSION - The spattering of small soil particles caused by the impact of raindrops on wet soils. The loosened and spattered particles may or may not be subsequently removed by surface runoff.
EROSION AND SEDIMENTATION CONTROL PLAN - A plan for the control of erosion and sediment resulting from a land-disturbing activity.
EROSION CLASSES (soil survey) - A grouping of erosion conditions based on the degree of erosion or on characteristic patterns; applied to accelerated erosion, not to normal, natural, or geological erosion. Four erosion classes are recognized for water erosion and three for wind erosion.
EROSION INDEX - An interaction term of kinetic energy times maximum 30-minute rainfall intensity that reflects the combined potential of raindrop impact and turbulence of runoff to transport dislodged soil particles from a field.
EROSIVE - Having sufficient velocity to cause erosion; refers to wind or water. Not to be confused with erodible as a quality of soil.
ESCARPMENT - A steep face or ridge of highland; the scarpenet of a mountain range is generally on that side nearest the sea.
EXISTING GRADE - The vertical location of the existing ground surface prior to cutting or filling.
FERTILIZER - Any organic or inorganic material of natural or synthetic origin that is added to a soil to supply elements essential to plant growth.
FERTILIZER ANALYSIS - The percentage composition of fertilizer, expressed in terms of nitrogen, phosphoric acid, and potash. For example, a fertilizer with a 6-12-6 analysis contains 6 percent nitrogen (N), 12 percent available phosphoric acid (P205) and 6 percent water-soluble potash (K2O). Minor elements may also be included. Recent analysis expresses the percentages in terms of the elemental fertilizer (nitrogen, phosphorus, potassium).
FILLING - The placement of any soil or other solid material either organic or inorganic on a natural ground surface or an excavation.
FILTER STRIP - A long, narrow vegetative planting used to retard or collect sediment for the protection of diversions, drainage basins or other structures.
FINAL CUT - The last cut or line of excavation made when mining a specific property or area.
FINISHED GRADE - The final grade or elevation of the ground surface forming proposed design.

F-4

GaSWCC (Amended - 2000)

FLOOD - An overflow or inundation that comes from a river or other body of water and causes or threatens damage.
FLOOD CONTROL - Methods or facilities for reducing flood flows.
FLOOD CONTROL PROJECT - A structural system installed for protection of land and improvements from floods by the construction of dikes, river embankments, channels, or dams.
FLOODGATE - A gate placed in a channel or closed conduit to keep out floodwater or tidal backwater.
FLOODPEAK - The highest value of the stage or discharge attained by a flood. The peak stage or peak discharge.
FLOODPLAIN - Nearly level land situated on either side of a channel which is subject to overflow flooding.
FLOODROUTING - Determining the changes in the rise and fall of floodwater as it proceeds downstream through a valley or reservoir.
FLOOD STAGE - The stage at which overflow of the natural banks of a stream begins to cause damage in the reach in which the elevation is measured.
FLOODWATER RETARDING STRUCTURE - A structure providing for temporary storage and controlled release of floodwater.
FLOODWAY - A channel, either natural, excavated, or bounded by dikes and levees, used to carry excessive flood flows to reduce flooding; sometimes considered to be the transitional area between the active channel and the floodplain.
FLUME - A device constructed to convey water on steep grades lined with erosion resistant materials.
FRAGIPAN - A natural subsurface horizon with high bulk density relative to the solum above, seemingly cemented when dry but showing a moderate to weak brittleness when moist. The layer is low in organic matter, mottled, slowly or very slowly permeable to water, and usually shows occasional or frequent bleached cracks forming polygons. It may be found in profiles of either cultivated or virgin soils but not in calcareous material.
FREEBOARD (hydraulics) - Vertical distance between the maximum water surface elevation anticipated in design and the top of retaining banks or structures provided to prevent overtopping because of unforeseen conditions.
GAGE OR GAUGE - Device for registering precipitation, water level, discharge, velocity, pressure, temperature, etc.

GAGING STATION - A selected section of a stream channel equipped with a gage, recorder, or other facilities for determining stream discharge.
GEOTEXTILE - A term used to describe woven or non-woven fabric materials used to reinforce or separate soil and other materials.
GRADATION (geology) - The bringing of a surface or a streambed to grade by running water. As used in connection with sedimentation and fragmental products for engineering evaluation, the term gradation refers to the frequency distribution of the various sized grains that constitute a sediment, soil, or material.
GRADE
(1) The slope of a road, channel, or natural ground.
(2) The finished surface of a canal bed, roadbed, top of embankment, or bottom of excavation; any surface prepared for the support of construction like paving or laying a conduit.
(3) To finish the surface of canal bed, roadbed, top of embankment, or bottom of excavation.
GRADED STREAM - A stream in which, over a period of years, the slope is delicately adjusted to provide, with available discharge and with prevailing channel characteristics, just the velocity required for transportation of the load (of sediment) supplied from the drainage basin. The graded profile is a slope of transportation. It is a phenomenon in which the element of time has a restricted connotation. Works of man are limited to his experience and of design and construction.
GRADE STABILIZATION STRUCTURE - A structure for the purpose of stabilizing the grade of a gully or other watercourse, thereby preventing further head-cutting or lowering of the channel grade.
GRADIENT - Change of elevation, velocity, pressure, or other characteristics per unit length; slope.
GRADING - Altering surfaces to specified elevations, dimensions, and/or slopes; this includes stripping, cutting, filling, stockpiling and shaping or any combination thereof and shall include the land in its cut or filled condition.
GRASS - A member of the botanical family Gramineae, characterized by bladelike leaves arranged on the culm or stem in two ranks.
GRASSED WATERWAY - A natural or constructed waterway, usually broad and shallow, covered with erosion-resistant grasses, used to conduct surface water from cropland.

GaSWCC (Amended - 2000)

F-5

GULLY - A channel or miniature valley cut by concentrated runoff but through which water commonly flows only during and immediately after heavy rains or during the melting of snow. A gully may be dendritic, or branching, or it may be linear; rather long, narrow, and of uniform width. The distinction between gully and rill is one of depth. A gully is sufficiently deep that it would not be obliterated by normal tillage operations, whereas a rill is of lesser depth and would be smoothed by use of ordinary tillage equipment. See Erosion, Rill.
GULLY EROSION - See Erosion.
GULLY CONTROL PLANTINGS - The planting of forage, legume, or woody plant seeds, seedlings, cuttings, or transplants in gullies to establish or re-establish a vegetative cover adequate to control runoff and erosion and incidentally produce useful products.
HABITAT - The environment in which the life needs of a plant or animal organism, population or community are supplied.
HEAD (hydraulics)
(1) The height of water above any plane of reference.
(2) The energy, either kinetic or potential, possessed by each unit weight of a liquid, expressed as the vertical height through which a unit weight would have to fall to release the average energy possessed; used in various compound terms such as pressure head, velocity head, and lost head.
(3) The internal pressure expressed in "feet" or pounds per square inch of an enclosed conduit.
HEAD GATE - Water control structure; the gate at the entrance to a conduit.
HEAD LOSS - Energy loss due to friction, eddies, changes in velocity, or direction of flow. Syn. frictionhead.
HEADWATER
(1) The source of stream.
(2) The water upstream from a structure or point on a stream.
HOOD INLET - Entrance to a closed conduit that has been shaped to induce full flow at minimum water surface elevation.
HYDROGRAPH - A graph showing variation in stage (depth) or discharge of a stream of water over a period of time.
F-6

IMPOUNDMENT - Generally an artificial collection or storage of water, as a reservoir, pit, dugout, sump, etc. Syn. reservoir.
INFILTRATION - The gradual downward flow of water from the surface through soil to ground water and water table reservoirs.
INFILTRATION RATE - A soil characteristic determining or describing the maximum rate at which water can enter the soil under specified conditions, including the presence of an excess of water.
INLET (hydraulics)
(1) A surface connection to a closed drain.
(2) A structure at the diversion end of a conduit.
(3) The upstream end of any structure through which water may flow.
INOCULATION - The process of introducing pure or mixed cultures or micro-organisms into natural or artificial cultural media.
INTAKE
(1) The headworks of a conduit, the place of diversion.
(2) Entry of water into soil. See Infiltration.
INTAKE RATE - The rate of entry of water into soil. See Infiltration Rate.
INTENSITY - Rainfall rate usually in/hr.
INTERCEPTION (hydraulics) - The process by which precipitation is caught and held by foliage, twigs, and branches of trees, shrubs, and other vegetation. Often used for "interception loss" or the amount of water evaporated from the precipitation intercepted.
INTERCEPTION CHANNEL - A channel excavated at the top of earth cuts, at the foot of slopes or at other critical places to intercept surface flow; a catch drain. Syn. Interception Ditches of water.
INLET (hydraulics)
(1) A surface connection to a closed drain.
(2) A structure at the diversion end of a conduit.
(3) The upstream end of any structure through which water may flow.
INOCULATION - The process of introducing pure or mixed cultures or micro-organisms into natural or artificial cultural media.
GaSWCC (Amended - 2000)

INTAKE
(1) The headworks of a conduit, the place of diversion.
(2) Entry of water into soil. See Infiltration.
INTAKE RATE - The rate of entry of water into soil. See Infiltration Rate.
INTENSITY - Rainfall rate usually in/hr.
INTERCEPTION (hydraulics) - The process by which precipitation is caught and held by foliage, twigs, and branches of trees, shrubs, and other vegetation. Often used for "interception loss" or the amount of water evaporated from the precipitation intercepted.
INTERCEPTION CHANNEL - A channel excavated at the top of earth cuts, at the foot of slopes or at other critical places to intercept surface flow; a catch drain. Syn. Interception Ditch.
INTERCEPTOR DRAIN - Surface or subsurface drain, or a combination of both, designed and installed to intercept flowing water.
INTERFLOW - That portion of rainfall that infiltrates into the soil and moves laterally through the upper soil horizons until intercepted by a stream channel or until it returns to the surface at some point downslope from its point of infiltration.
INTERMITTENT STREAM - A stream or portion of a stream that flows only in direct response to precipitation. It receives little or no water from springs and no long-continued supply from melting snow or other sources. It is dry for a large part of the year, ordinarily more than 3 months.
INTERNAL SOIL DRAINAGE - The downward movement of water through the soil profile. The rate of movement is determined by the texture, structure, and other characteristics of the soil profile and underlying layers and by the height of the water table, either permanent or perched. Relative terms for expressing internal drainage are: none, very slow, slow, medium, rapid, and very rapid.
LAND - The total natural and cultural environment within which production takes place; a broader term than soil. In addition to soil, its attributes include other physical conditions, such as mineral deposits, climate, and water supply; location in relation to centers of commerce, population, and other land; the size of the individual tracts or holdings; and existing plant cover, works of improvement, and the like. Some use the terms loosely in other senses: as defined above but without the economic or cultural criteria; especially in the expression "natural land" as a synonym for "soil"; for the solid sur-

face of the earth; and also for earthy surface formations, especially in the geomorphological expression "land form".
LAND CAPABILITY - The suitability of land for use without permanent damage. Land capability, as ordinarily used in the United States, is an expression of the effect of physical land conditions, including climate, on the total suitability for use without damage for crops that require regular tillage, for grazing, for woodland, and for wildlife. Land capability involves consideration of (1) the risks of land damage from erosion and other causes and (2) the difficulties in land use owing to physical land characteristics, including climate.
LAND CAPABILITY CLASSIFICATION - A grouping of kinds of soils into special units, subclasses, and classes according to their capability for intensive use and the treatments required for sustained use. (Prepared by the Natural Resources Conservation Service, USDA.)
LAND CAPABILITY MAP - A map showing land capability units, subclasses and classes, or a soil survey map colored to show land capability classes.
LAND CAPABILITY UNIT - Capability units provide more specific and detailed information for application to specific fields on a farm or ranch than the subclass of the land capability classification. A capability unit is group of soils that are nearly alike in suitability for plant growth and responses to the same kinds of soil management.
LAND CLASSIFICATION - The arrangement of land units into various categories based on the properties of the land or its suitability for some particular purpose.
LAND-DISTURBING ACTIVITY - Any land change which may result in soil erosion from water or wind and the movement of sediments into State water or onto lands within the State, including, but not limited to, clearing, dredging, grading, excavating, transporting and filling of land.
LAND FORM - A discernible natural landscape, such as a floodplain, stream terrace, plateau, valley, etc.
LAND RECLAMATION - Making land capable of more intensive use by changing its general character, as by drainage of excessively wet land; irrigation of arid or semiarid land; or recovery of submerged land from seas, lakes, and rivers. Large-scale reclamation projects usually are carried out through collective effort. Simple improvements, such as cleaning of stumps or stones from land, should not be referred to as land reclamation.
LEACHING - The removal from the soil in solution of the more soluble materials by percolating waters.

GaSWCC (Amended - 2000)

F-7

LEGUME - A member of the legume or pulse family, Leguminosae. One of the most important and widely distributed plant families. The fruit is a "legume" or pod that opens along two sutures when ripe. Flowers are usually papilionaceous (butterflylike). Leaves are alternate, have stipules, and are usually compound. Includes many valuable food and forage species, such as the peas, beans, peanuts, clover, alfalfas, sweet clovers, lespedezas, vetches, and kudzu. Practically all legumes are nitrogen-fixing plants.
LEVEL SPREADER - A shallow channel excavation at the outlet end of a diversion with a level section for the purpose of diffusing the diversion out-flow.
LIME - Lime, from the strictly chemical standpoint, refers to only one compound, calcium oxid (CaO); however, the term "lime" is commonly used in agriculture to include a great variety of materials which are usually composed of the oxide, hydroxide, or carbonate of calcium or of calcium and magnesium. The most commonly used forms of agriculture lime are ground limestone (carbonates), hydrated lime (hydroxides), burnt lime (oxides), marl, and oyster shells.
LIME, AGRICULTURAL - A soil amendment consisting principally of calcium carbonate, but including magnesium carbonate and perhaps other materials, used to furnish calcium and magnesium as essential elements for the growth of plants and to neutralize soil acidity.
LIMING - The application of lime to land, primarily to reduce soil acidity and supply calcium for plant growth. Dolomitic limestone supplies both calcium and magnesium. It may also improve soil structure, organic matter content, and nitrogen content of the soil by encouraging the growth of legumes and soil microorganisms. Liming an acid soil to pH value of about 6.5 is desirable for maintaining a high degree of availability of most of the nutrient elements required by plants.
LIQUEFICATION (spontaneous liquefication) - The sudden large decrease of the shearing resistance of a cohesionless soil, caused by a collapse of the structure from shock or other type of strain and associated with a sudden but temporary increase in the pore-fluid pressure. It involves a temporary transformation of the material into a fluid mass.
LIQUID LIMIT (LL) - The water content corresponding to the arbitrary limit between the liquid and plastic states of consistency of a soil.
LITTER - In forestry, a surface layer of loose organic debris in forests, consisting of freshly fallen or slightly decomposed organic materials.
LOAMY - Intermediate in texture and properties between fine-textured and coarse-textured materials.
LOOSE ROCK DAM - A dam built of rock without the use of mortar, a rubble dam. See Rock-Fill Dam.
F-8

MADE LAND - Areas filled with earth or earth and trash mixed, usually made by or under the control of man. A miscellaneous land type.
MANNING'S FORMULA (hydraulics) - A formula used to predict the velocity of water flow in an open channel or pipelines:
V = 1.486r2/3 S1/2 n
wherein V is the mean velocity of flow in feet per second; r is the hydraulic radius; s is the slope of the energy gradient or for assumed uniform flow the slope of the channel in feet per foot; and n is the roughness coefficient or retardance factor of the channel lining.
MEAN DEPTH (hydraulics) - Average depth; crosssectional area of a stream or channel divided by its surface or top width.
MEAN VELOCITY - Average velocity obtained by dividing the flow rate discharge by the cross-sectional area for that given cross-section.
MEASURING WEIR - A shaped notch through which water flows are measured. Common shapes are rectangular, trapezoidal, and triangular.
MECHANICAL ANALYSIS - The analytical procedure by which soil particles are separated to determine the particle size distribution.
MECHANICAL PRACTICES - Soil and water conservation practices that primarily change the surface of the land or that store, convey, regulate, or dispose of runoff water without excessive erosion. See Structural Practices.
MONOLITHIC - Of or pertaining to a structure formed from a single mass of stone.
MOUNTAIN TOP REMOVAL - A mining method in which 100 percent of the overburden covering a mineral deposit is removed in order to recover 100 percent of the mineral. Excess spoil material is hauled to a nearby hollow to create valley fill.
MOVEABLE DAM - A moveable barrier that may be opened in whole or in part, permitting control of the flow of water through or over the dam.
MUCK SOIL
(1) An organic soil in which the organic matter is well decomposed (USA usage).
(2) A soil containing 20 to 50 percent organic matter.
MULCH - A natural or artificial layer of plant residue or other materials, such as sand or paper, on the soil surface.
GaSWCC (Amended - 2000)

NATURAL GROUND SURFACE - The ground surface in its original state before any grading, excavation or filling.
NOISE POLLUTION - The persistent intrusion of noise into the environment at a level that may be injurious to human health.
NORMAL DEPTH - Depth of flow in an open conduit during uniform flow for the given conditions. See Uniform Flow.
OPEN DRAIN - Natural watercourse or constructed open channel that conveys drainage water.
OUTFALL - Point where water flows from a conduit, stream, or drain.
OUTLET - Point of water disposal from a stream, river, lake, tidewater, or artificial dam.
OUTLET CHANNEL - A waterway constructed or altered primarily to carry water from man-made structures, such as terraces, tile lines, and diversions.
OVERFALL - Abrupt change in stream channel elevation; the part of a dam or weir over which the water flows.
OVERHAUL - Transportation of excavated material beyond a specified haul limit, usually expressed in cubic yard stations (1 cubic yard hauled 100 feet).
PARENT MATERIAL (soils) - The unconsolidated, more or less chemically weathered, mineral or organic matter from which the solum of soils has developed by pedogenic processes. The C horizon may or may not consist of materials similar to those from which the A and B horizons developed.
PEAK DISCHARGE - The maximum instantaneous flow from a given storm condition at a specific location.
PERCOLATION - The downward movement of water through soil, especially the downward flow of water in saturated or nearly saturated soil at hydraulic gradients of the order of 1.0 of less.
PERMEABILITY - Capacity for transmitting a fluid. It is measured by the rate at which a fluid of standard viscosity can move through material in a given interval of time under a given hydraulic gradient.
PERMEABILITY, soil - The quality of soil horizon that enables water or air to move through it.The permeability of a soil may be limited by the presence of one nearly impermeable horizon even though the others are permeable.
pH - A numerical measure of the acidity or hydrogen ion activity. The neutral point is pH 7.0. All pH values below 7.0 are acid and all above are alkaline.
PIPE DROP - A circular conduit used to convey water down steep grades.
GaSWCC (Amended - 2000)

PLASTICITY INDEX (PI) - The numerical difference between the liquid limit and the plastic limit.
PLASTIC LIMIT (PL) - The water content corresponding to an arbitrary limit between the plastic and semisolid states of consistency of soil.
PLASTIC SOIL - A soil capable of being molded or deformed continuously and permanently by relatively moderate pressure.
PLUNGE POOL - A device used to dissipate the energy of flowing water that may be constructed or made by the action of flowing. These facilities may be protected by various lining materials.
POOLS - Areas of a stream where the velocity provides a favorable habitat for plankton. Silts and other loose materials that settle to the bottom of pools are favorable for burrowing forms of benthos. Syn. riffle.
PRINCIPAL SPILLWAY - A water conveying device generally constructed of permanent material and designed to regulate the normal water level, provide flood protection and/or reduce the frequency of operation of the emergency spillway.
PURE LIVE SEED (PLS) - A term used to express the quality of seed, even if it is not shown on the label. Expressed as a percentage of the seeds that are pure and will germinate. Determined by multiplying the percent of pure seed times the percents of germination and dividing by 100.
RATIONAL FORMULA - Q = CIA. Where "Q" is the peak discharge measured in cubic feet per second, "C" is the runoff coefficient reflecting the ratio of runoff to rainfall, "I" is the rainfall intensity for the duration of the storm measured in inches per hour, and "A" is the area contributing drainage measured in acres.
RELIEF DRAIN - A drain designed to remove water from the soil in order to lower the water table and reduce hydrostatic pressure.
RELIEF WELL - Well, pit, or bore penetrating the water table to relieve hydrostatic pressure by allowing flow from the aquifer.
RESTORATION - The process of restoring site conditions as they were before the land disturbance.
RETURN FLOW - That portion of the water diverted from a stream that finds its way back to the stream channel either as surface or underground flow.
RILL - A small intermittent watercourse with steep sides, usually only a few inches deep and thus no obstacle to tillage operations.
RILL EROSION - See Erosion.
F-9

RIPRAP - Broken rock, cobbles, or boulders place on earth surfaces, such as the face of a dam or the bank of a stream for protection against the action of water (waves); also applied to brush or pole mattresses, or brush and stone, or other similar materials used for soil erosion control.
RISER - The inlet portions of drop inlet spillway that extend vertically from the pipe conduit barrel to the water surface.
RIVER BASIN - A major water resource region. The United States has been divided into 20 river basin areas.
ROCK-FILL DAM - A dam composed of loose rock usually dumped in place, often with the upstream part constructed of handplaced or derrick-placed rock and faced with rolled earth or with an impervious surface of concrete, timber, or steel.
RUNOFF (hydraulics) - That portion of the precipitation on a drainage area that is discharged from the area in stream channels. Types include runoff, groundwater runoff, or seepage.
SCARIFY - To abrade, scratch, or modify the surface; for example, to scratch the impervious seed coat of hard seed or to break the surface of the soil with a narrow-bladed implement.
SCREENING - The use of any vegetative planting, fencing, ornamental wall of masonry, or other architectural treatment, earthen embankment, or a combination of any of these which will effectively hide from view any undesirable areas from the main traveled way.
SEDIMENT - Solid material, both mineral and organic, that is in suspension, is being transported, or has been moved from its site of origin by air, water, gravity, or ice, as a product of erosion.
SEDIMENT BASIN - A depression formed from the construction of a barrier or dam built at a suitable location to retain sediment and debris.
SEDIMENT DISCHARGE - The quantity of sediment, measured in dry weight or by volume, transported through a stream cross-section in a given time. Sediment discharge consists of both suspended load and bedload.
SEDIMENT LOAD - See Sediment Discharge.
SEDIMENT POOL - The reservoir space allotted to the accumulation of submerged sediment during the life of the structure.
SEEDBED - The soil prepared by natural or artificial means to promote the germination of seed and the growth of seedlings.
F-10

SEEPAGE
(1) Water escaping through or emerging from the ground along an extensive line or surface as contrasted with a spring where the water emerges from a localized spot.
(2) (percolation) The slow movement of gravitational water through the soil.
SHEET FLOW - Water, usually storm runoff, flowing in a thin layer over the ground surface; also called overland flow.
SHRINK-SWELL POTENTIAL - Susceptibility to volume change due to loss or gain in moisture content.
SHRINKAGE INDEX (SI) - The numerical difference between the plastic and shrinkage limits.
SHRINKAGE LIMIT (SL) - The maximum water content at which a reduction in water content will not cause a decrease in the volume of the soil mass. This defines the arbitrary limit between the solid and semi-solid states.
SIDE SLOPE - Generic term used to describe slope of earth-moving operations, generally stated in horizontal to vertical ratio.
SILT
(1) A soil separate consisting of particles between 0.05 and 0.002 millimeter in equivalent diameter.
(2) A soil textural class.
SILTING - See Sediment.
SILT LOAM - A soil textural class containing a large amount of silt and small quantities of sand and clay.
SILTY CLAY - A soil textural class containing a relatively large amount of silt and clay and a small amount of sand.
SILTY CLAY LOAM - A soil textural class containing a relatively large amount of silt, a lesser quantity of clay, and a still smaller quantity of sand.
SLOPE - The degree of deviation of a surface from horizontal, measured in a numerical ratio, percent, or degrees. Expressed as a ratio or percentage, the first number is the vertical distance (rise) and the second is the horizontal distance (run), as 2:1 or 200 percent. Expressed in degrees, it is the angle of the slope from the horizontal plane with a 90I slope being vertical (maximum) and 45I being a 1:1 slope.
GaSWCC (Amended - 2000)

SLOPE CHARACTERISTICS - Slopes may be characterized as concave (decrease in steepness in lower portion), uniform, or convex (increase in steepness at base). Erosion is strongly affected by shape, ranked in order of increasing erodibility from concave to uniform to convex.
SOIL - The unconsolidated mineral and organic material on the immediate surface of the earth that serves as a natural medium for the growth of land plants.
SOIL AMENDMENT - Any material, such as lime, gypsum, sawdust, or synthetic conditioner, that is worked into the soil to make it more amenable to plant growth.
SOIL HORIZON - A layer of soil or soil material approximately parallel to the land surface and differing from adjacent genetically related layers in physical, chemical, and biological properties or characteristics, such as color, structure, texture consistence, kinds and numbers of organisms present, degree of alkalinity, etc.
SOIL PROFILE - A vertical section of the soil from the surface through all horizons, including C horizons.
SPILLWAY - An open or closed channel, or both, used to convey excess water from a reservoir. It may contain gates, either manually or automatically controlled, to regulate the discharge of excess water.
SPOIL - Soil or rock material excavated from a canal, ditch, basin, or similar construction.
STABILIZATION - The process of establishing an enduring soil cover of vegetation and/or mulch or other ground cover in combination with installing temporary or permanent structures for the purpose of reducing to a minimum the transport of sediment by wind, water, ice or gravity.
STABILIZED GRADE - The slope of a channel at which neither erosion nor deposition occurs.
STAGE (hydraulics) - The variable water surface or the water surface elevation above any chosen datum. See Gaging Station.
STATE SOIL AND WATER CONSERVATION COMMISSION - The state agency established by soil and water conservation district enabling legislation to assist with the administration of the provisions of that law.
STORM DRAIN OUTLET PROTECTION STRUCTURE - A device used to dissipate the energy of flowing water. Generally constructed of concrete or rock in the form of a partially depressed or partially submerged vessel and may utilize baffles to dissipate velocities.
STORM FREQUENCY - An expression or measure of how often a hydrologic event of a given size or magnitude should on an average occur, based on a reasonable sample.
GaSWCC (Amended - 2000)

STREAMBANKS - The usual boundaries, not the flood boundaries, of a stream channel. Right and left banks are named facing downstream.
STREAM GAGING - The quantitative determination of stream flow using gages, current meters, weirs, or other measuring instruments at selected locations. See Gaging Station.
STREAM LOAD - Quantity of solid and dissolved material carried by a stream. See Sediment Load.
STRUCTURAL PRACTICES - Soil and water conservation measures, other than vegetation, utilizing the mechanical properties of matter for the purpose of either changing the surface of the land or storing, regulating, or disposing of runoff to prevent excessive sediment loss. Including but not limited to riprap, sediment basins, dikes, level spreaders, waterways or outlets, diversions, grade stabilization structures, sediment traps, land grading, etc. See Mechanical Practices.
SUBSOIL - The B horizons of soils with distinct profiles. In soils with weak profile development, the subsoil can be defined as the soil below the plowed soil (or its equivalent of surface soil), in which roots normally grow. Although a common term, it cannot be defined accurately. It has been carried over from early days when "soil" was conceived only as the plowed soil and that under it as the "subsoil".
SUBWATERSHED - A watershed subdivision of unspecified size that forms a convenient natural unit.
TERRACE - An embankment or combination of an embankment and channel across a slope to control erosion by diverting or storing surface runoff instead of permitting it to flow uninterrupted down from the soil.
TILE, DRAIN - Pipe made of burned clay, concrete, or similar material, in short lengths, usually laid with open joints to collect and carry excess water from the soil.
TILE DRAINAGE - Land drainage by means of a series of tile lines laid at a specified depth and grade.
TILTH - A soil's physical condition as related to its ease to work (till).
TOE (engineering) - Terminal edge or edges of a structure.
TOE DRAIN - Interceptor drain located near the downstream toe of a structure.
TOPSOIL - Earthy material used as top-dressing for house lots, grounds for large buildings, gardens, road cuts, or similar areas. It has favorable characteristics for production of desired kinds of vegetation or can be made favorable.
F-11

TRASH RACK - A structural device used to prevent debris from entering a spillway or other hydraulic structure.
UNIFIED SOIL CLASSIFICATION SYSTEM (engineering) - A classification system based on the identification of soils according to their particle size, gradation, plasticity index, and liquid limit.
UNIFORM FLOW - A state of steady flow when the mean velocity and cross-sectional area are equal at all sections of a reach.
UNIVERSAL SOIL LOSS EQUATION - An equation used for the design of water erosion control systems: A = RKLSCP wherein A = average annual soil loss in tons per acre per year; R = rainfall factor; K = soil erodibility factor; L = length of slope; S = percent of slope; C = cropping and management factor; and P = conservation practice factor.
VEGETATIVE MEASURES - Stabilization of erosive or sediment-producing areas by covering the soil with:
(a) Permanent seeding, producing long-term vegetative cover, or
(b) Short-term seeding, producing temporary vegetative cover, or
(c) Sodding, producing areas covered with a turf of perennial sod-forming grass.
WATER CLASSIFICATION - separation of water of an area into classes according to usage, such as domestic consumption, fisheries, recreation, industrial, agricultural, navigation, waste disposal, etc.
WATER CONSERVATION - The physical control, protection, management, and use of water resources in such a way as to maintain crop, grazing, and forest lands; vegetal cover; wildlife; and wildlife habitat for maximum sustained benefits to people, agriculture, industry, commerce, and other segments of the national economy.
WATER CONTROL (soil and water conservation) The physical control of water by such measures as conservation practices on the land, channel improvement, and installation of structures for water retardation and sediment detention (does not refer to legal control or water rights as defined).
WATER CUSHION - Pool of water maintained to absorb the impact of water flowing from an overfall structure.
WATER DEMAND - Water requirements for a particular purpose, such as irrigation, power, municipal supply, plant transpiration, or storage.

WATER DISPOSAL SYSTEM - The complete system for removing excess water from land with minimum erosion. For sloping land, it may include a terrace system, terrace outlet channels, dams and grassed waterways. For level land, it may include surface drains or both surface and subsurface drains.
WATER QUALITY STANDARDS - Minimum requirements of purity of water for various uses; for example, water for agricultural use in irrigation systems should not exceed specific levels of sodium bicarbonates, pH total dissolved salts, etc.
WATER RESOURCES - The supply of groundwater and surface water in a given area.
WATERCOURSE - Any natural or artificial watercourse, stream, river, creek, channel, ditch, canal, conduit, drain, waterway, gully, ravine, or wash in which water flows either continuously or intermittently and which has a definite channel, bed and banks, and including any area adjacent thereto subject to inundation by reason of overflow or floodwater.
WATERSHED AREA - All land and water within the confines of a drainage divide or a water problem area consisting in whole or in part of land needing drainage or irrigation.
WATERSHED LAG - Time from center of mass of effective rainfall to peak of hydrograph.
WATERSHED MANAGEMENT - Use, regulation, and treatment of water and land resources of a watershed to accomplish stated objectives.
WATERSHED PLANNING - Formulation of a plan to use and treat water and land resources.
WATERWAY - An natural course or constructed channel for the flow of water. See Grassed Waterway.
WEIR - Device for measuring or regulating the flow of water.
WEIR NOTCH - The opening in a weir for the passage of water.
WETTING AGENT - A chemical that reduces the surface tension of water and enables it to soak into porous material more readily.
This glossary was compiled from definitions supplied by the Natural Resources Conservation Service, Soil and Water Conservation Society of America, Resource Conservation Glossary, and other state and federal publications.

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REFERENCES
1. Agricultural Research Service and Environmental Protection Agency, Control of Water Pollution From Cropland, ARS-H-5-1 or Environmental Protection Agency-600/2-75-026a, November, 1975.
2. Baltimore County, Maryland, Sediment Control Manual, October, 1968.
3. Barnett, A.P. and B.H. Hendrickson, "Erosion on Piedmont Soils," Soil Conservation Magazine, USDA, Soil Conservation Service, Volume XXVI, No. 2, Sept., 1960.
4. Cooperative Extension Service, Ohio, Ohio Erosion Control and Sediment Pollution Abatement Guide, Bulletin 594, March, 1975.
5. Davis, Raymond E., F.S. Foote, and J. W. Delly, Surveying Theory and Practice, McGraw-Hill Book Company, 1968.
6. Department of Natural Resources, Georgia, Land Reclamation Performance Standards, Draft copy, October 1975.
7. Department of Natural Resources, West Virginia, Drainage Handbook for Surface Mining, January, 1975.
8. Department of Public Works, Division of Highways, California, Bank and Shore Protection in California Highway Practice, November, 1970.
9. Department of Transportation, Georgia, Standard Specifications: Construction of Roads and Bridges, 1993.
10. Diseker, E. G., and Richardson, E.C., Transaction of the American Society of Agricultural Engineers, St. Joseph, Michigan, vol. 1, No. 1, pp 62-64, 68.
11. Environmental Protection Agency, Guidelines for Erosion and Sediment Control Planning and Implementation, Environmental Protection Agency-R2-72-015, August 1972.
12. Environmental Protection Agency, Control of Erosion and Sediment Deposition From Construction of Highways and Land Development, September, 1971.
13. Environmental Protection Agency, Methods and Practices for Controlling Water Pollution From Agricultural NonPoint Sources, Environmental Protection Agency-430/9-73-015, October, 1973.
14. Environmental Protection Agency, Proceedings Workshop on Agricultural Non-Point Source Water Pollution Control, September 16-17, 1974, Mayflower Hotel, Washington, D.C.
15. Environmental Protection Agency, Guidelines for Erosion and Sediment Control Planning and Implementation, Environmental Protection Agency-430/9-73-014, October, 1973.
16. Environmental Protection Agency, Processes, Procedures, and Methods to Control Pollution Resulting from All Construction Activity, Environmental Protection Agency-430/9-73-007, October, 1973.
17. Federal Highway Administration, Suggestions for Temporary Erosion and Siltation Control Measures, February, 1973.
18. Georgia Soil and Water Conservation Commission, Georgia Governor's Conference on Sediment Control, Center for Continuing Education, Athens, Georgia, July 22-24, 1973.
19. Georgia Soil and Water Conservation Commission, Guidelines for Streambank Restoration, September, 1994.
20. Inman, Ernest J., Flow Characteristics of Georgia's Streams, United States Department of the Interior, Geological Survey, open file report, Atlanta, Georgia, 1971.
21. Kostielney, Janet L," Erosion Control and Crop Farming," Erosion Control, April, 1999.

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22. Meyer, L.D., "Overview of the Urban Erosion and Sedimentation Process," Proceedings of National Symposium on Urban Rainfall and Runoff and Sediment Control, July 29-31, 1974.
23. Michigan Department of Natural Resources, Michigan Soil Erosion and Sedimentation Control Guidebook, February, 1975.
24. National Association of Counties Research Foundation, Community Action Guidebook for Soil Erosion and Sediment Control, March 1970.
25. National Association of Counties Research Foundation, Urban Soil Erosion and Sediment Control, Program #15030DTL, May 1970.
26. New Jersey State Soil Conservation Committee, Standards for Soil Erosion and Sediment Control in New Jersey.
27. Pennsylvania Department of Environmental Resources, Soil Erosion and Sedimentation Control Manual for Agriculture, 1998.
28. Soil and Water Conservation Society of America, Soil Erosion: Prediction and Control, 1977.
29. Soil Conservation Service, Engineering Field Manual, September 1969.
30. Soil Conservation Service, Georgia, Manual of Standards and Specifications for Control of Soil Erosion and Sediment in Areas Undergoing Urban Development, July 1972.
31. Soil Conservation Service, Guide to Sedimentation Investigation, Technical Guide No. 12, September, 1975.
32. Soil Conservation Service, Guidelines for the Control of Erosion and Sediment in Urban Areas of the Northeast, August, 1970.
33. Soil Conservation Service, Michigan Program for Soil Erosion and Sedimentation Control, July 1973.
34. Soil Conservation Service, Mississippi, Guidelines for the Control of Erosion and Sediment in Urbanizing Areas Within Mississippi, August, 1975.
35. Soil Conservation Service, National Engineering Handbook, Section 3, Sedimentation, Section 4, Hydrology.
36. Soil Conservation Service, North Carolina, Guide for Sediment Control on Construction Sites in North Carolina, March, 1973.
37. Soil Conservation Service, Ohio, Water Management and Sediment Control for Urbanizing Areas, April, 1972.
38. Soil Conservation Service, Planning and Design of Open Channels, Technical Release No. 25, December, 1964.
39. Soil Conservation Service, Procedure for Computing Sheet and Rill Erosion on Project Areas, Technical Release No. 51, Geology, January 1975.
40. Soil Conservation Service, Standards and Specification for Soil Erosion and Sediment Control in Urbanizing Areas, November, 1968.
41. Soil Conservation Service, Urban Hydrology for Small Watersheds, 2nd Edition, Technical Release No. 55, June, 1986.
42. United States Forestry Service, Tractor Attachments for Brush, Slash and Root Removal, ED & T 1332, January, 1971.
43. United States Geological Survey Water - Data Report Georgia-75-1, Water Resources Data for Georgia Water Year 1975, Georgia-75-1.

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44. USDA Agricultural Research Service, PAMphlet: a concise guide for safe and practical use of polyacry-lamide(PAM) for irrigation-induced erosion control and infiltration enhancement. USDA-ARS Northwest Irrigation and Soils Research Laboratory Station Note #02-98.
45. USDA Agricultural Research Service, Predicting Rainfall Erosion Losses - A Guide to Conservation Planning, Agriculture Handbook Number 537, 1978.
46. USDA Agricultural Research Service, Predicting Soil Erosion by Water - A guide to Conservation Planning with the Revised Universal Soil Loss Equation (RUSLE), Agriculture Handbook Number 703, Draft, 1993.
47. USDA Natural Resources Conservation Service, Erosion Prediction, Field Office Technical Guide, May, 1993.
48. USDA Natural Resources Conservation Service, Conservation Practice Standard, Critical Area Planting (Acre), CODE 342, Georgia, April 1999.
49. University of Georgia, Institute of Ecology, Office of Public Service & Outreach, A Review of the Scientific Literature on Riparian Buffer Width, Extent and Vegetation, Seth Wenger, March, 1999.
50. Virginia Soil and Water Conservation Commission, Virginia Erosion and Sediment Control Handbook, 3rd Edition, 1992.
51. Wischmeier, W.H., C.B. Johnson and B.V. Cross, A Soil Erodibility Nomograph for Farmland and Construction Sites. Journal of Soil and Water Conservation 26(5): 189-193, 1971.

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