GEOHYDROLOGY OF BARTOW, CHEROKEE, AND FORSYTH COUNTIES, GEORGIA by C.W. Cressler, H.E . Blanchard,Jr., and W.G. Hester . ._..... ...... .. .. ,. .~ ;. - . ,./ " . . : , . -~ . ..... .) .... - . . .,. " - :' .,.. _!,'" ""r .. : Georgia Department of Natural Resources Georgia Geologic Survey ... 50 INF'ORMATION CIRCULAR For convenience in selecting our reports from your bookshelves, they will be color-keyed across the spine by subject as follows: Red Dk. Purple Maroon Lt. Green Lt. Blue Dk .. Green Dk. Blue Olive Yellow Dk. Orange Brown Black Dk. Brown Valley and Ridge mapping and structural geology Piedmont and Blue Ridge mapping and structural geology Coastal Plain mapping and stratigraphy Paleontology Coastal Zone studies Geochemical and Geophysical studies Hydrology Economic geology Mining directory Environmental studies Engineering studies Bibliographies and lists of publications Petroleum and natural gas Field trip guidebooks Collections of papers Colors have been selected at random and will be augmented as new subjects are published. GEOHYDROLOGY OF BARTOW, CHEROKEE, AND FORSYTH COUNTIES, GEORGIA by C.W. Cressler, H.E. Blanchard,Jr., and W.G. Hester GEORGIA DEPARTMENT OF NATURAL RESOURCES Joe D. Tanner, Commissioner ENVIRONMENTAL PROTECTION DIVISION J. Leonard Ledbetter, Director GEORGIA GEOLOGIC SURVEY William H. McLemore, State Geologist Prepared in cooperation with the U.S. GEOLOGICAL SURVEY Atlanta 1979 50 . INFORMATION CIRCULAR CONTENTS Page Conversion table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Purpose and scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Location and extent of area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Previous studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Acknowledgements ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Occurrence and availability of ground water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Description of the water-bearing units and their hydrologic properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Water-bearing unit A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Character of the rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Water-bearing character. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Water-bearing unit C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Character of the rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Water-bearing character ................................................................... 11 Water-bearing unit D ....................................................................... 11 Character of the rock ..................................................................... 11 Water-bearing character . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Water-bearing unit F ....................................................................... 12 Character of the rock ..................................................................... 12 Water-bearing character ................................................................... 13 Water-bearing unit G ....................................................................... 13 Character of the rock ..................................................................... 13 Water-bearing character ................................................................... 14 Water-bearing unit J ........................................................................ 14 Character of the rock ..................................................................... 14 Water-bearing character ................................................................... 14 Water-bearing unit K ....................................................................... 14 Character of the rock ..................................................................... 14 Water-bearing character ................................................................... 15 Water-bearing unit L ....................................................................... 15 Character of the rock ..................................................................... 15 Water-bearing character ................................................................... 15 Water-bearing unit :'lo/ 15 Character of the rock ..................................................................... 15 Water-bearing unit character ............................................................... 15 Water-bearing unit P ....................................................................... 16 Character of the rock ..................................................................... 16 Water-bearing character ................................................................... 16 Use of ground water ........................................................................... 16 Wells ..................................................................................... 16 Springs ................................................................................... 16 Chemical quality of ground water ............................................................... 17 Fluctuations in spring flow ..................................................................... 17 Land subsidence and sinkhole formation ......................................................... 17 Ground-water pollution ........................................................................ 18 Pollution of wells .......................................................................... 18 Pollution of springs ......................................................................... 18 Ill CONTENTS (Continued) Page Ground-water pollution by landfill leachate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Bartow County landfill ........................................................................ 21 Movement of leachate overland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Movement of leachate underground. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Other open-pit mines in the Cartersville area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Methods for evaluating well sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Evaluating sites ............................................................... 27 Other factors affecting well yields .............................................. . . 30 High-yielding wells ............................................................... 31 Fault zones ............................................................... 31 Zones of fracture concentration ...................................................... ... 32 Contact zones between rocks of contrasting character ............................................. 35 Conclusions ......................................................................... . 39 Selected references .................................................................... . 39 Appendix ....................................................................... .. 41 ILLUSTRATIONS Plate I. Map showing water-bearing units and locations of selected wells and springs, Bartow County, Georgia ......................................................................... . in pocket 2. Map showing water-bearing units and locations of selected wells, Cherokee County, Georgia in pocket 3. Map showing water-bearing units and locations of selected wells, Forsyth County, Georgia . in pocket 4. Geologic map of the Cartersville area, Bartow County, Georgia ........................ . in pocket 5. Map of open-pit mines in the Cartersville, Georgia area large enough to be potential landfill sites in pocket Figure I. Map showing location of report area ................................................ . 3 2. Map showing relative risk of sinkholes forming near high-yielding wells in Bartow County .. 19 3. Geology of Bartow County landfill area, showing direction of surface leachate movement ... 20 4. Diagram showing how leachate escaping from a landfill moves down the hydraulic gradient. 24 5. Map showing water-level configuration in Cartersville, 1976, and direction that leachate may move underground from the Bartow County landfill .................................. . 25 6. Diagram showing escape of landfill leachate through breach of bottom material .......... . 26 7. Topographic map and profiles of ground surface showing rating in points for various topographic positions ........................................................................ . 28 8. Graph showing rating in points for various conditions of soil thickness .................. . 28 9. Graph indicating probability of getting a certain yield from a well at different sites having various total-point ratings ................................................................ . 28 10. Photograph of countryside showing approximate ratings for topography ................. . 30 II. Cross section of sheeted terrane showing water-filled joints in heavy dark lines ........... . 31 12. Block diagram showing how zones of fracture concentration consist of nearly vertical, closely spaced fractures .................................................................. . 33 13. Block diagram showing valley development localized along zones of fracture concentration . 34 14. Block diagram illustrating how straight stream segments, abrupt angular changes in valley alignment, and alignment of sinkholes indicate the presence of zones of fracture concentration 35 15. Map showing relation of zones of fracture concentration to well yields, Lake Arrowhead area 36 16. Topographic map showing typical intermittent stream valleys in carbonate terrane, Bartow County ......................................................................... . 37 17. Topographic map showing how permeable zones of fracture concentration commonly lie along straight valley segments ........................................................... . 38 IV TABLES Table l. Chemical analyses of well water, Bartow, Cherokee, and Forsyth Counties.. . . . . . . . . . . . . . . 2. Minor chemical constituents in well and spring water, Bartow, Cherokee, and Forsyth Counties 3. Measured or estimated flows of springs, Bartow County . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. Chemical analyses of spring water,Bartow County . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5. Concentrations of metals and chloride in water sampled downstream from the Bartow County landfill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6. Use of numerical rating of well site to estimate the percent chance of success of a well. . . . . . Page 7 8 9 10 22 29 APPENDIX Table 7. Record of wells in Bartow County . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 8. Record of wells in Cherokee County . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 9. Record of wells in Forsyth County . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 FACTORS FOR CONVERTING INCH-POUND UNITS TO INTERNATIONAL SYSTEM (SI) UNITS The following factors may be used to convert the inch-pound units published herein to the International System of Units (Sl). Multiply inch-pound mch (in.) foot (ft) mile (mi) square mile (mi2) gallon (gal) million gallon (Mgal) gallon per minute (gal/ min) millon gallon per day (Mgaljd) By To obtain SI units 2.54 .3048 1.609 2.590 3. 785 3785 .06309 .04381 centimeter (em) meter (m) kilometer (km) square kilometer (km2) liter (L) cubic meter (m3) liter per second (Ljs) cubic meter per second (m3fs) v GEOHYDROLOGY OF BARTOW, CHEROKEE, AND FORSYTH COUNTIES, GEORGIA By C. W. Cressler, H. E. Blanchard, Jr.,and W. G. Hester ABSTRACT Bartow, Cherokee, and Forsyth Counties border the Atlanta Metropolitan Area, and are experiencing a rapid growth in urban and industrial development. Large areas not served by public water distribution systems rely on ground water to meet their requirements. Many new industries, resort communities, subdivisions, and private homes depend on ground water., most of which comes from wells. The western part of Bartow County lies in the Valley and Ridge physiographic province, where rocks range in age from Early Cambrian to Middle Ordovician. The principal water-bearing units are shale, limestone, dolomite, and quartzite. In this area, well supplies of 3 to 25 gal/min (0.2 to 1.6 L/s) can be obtained nearly everywhere and, with rare exceptions, the water is moderately mineralized and is suitable for domestic and stock supplies. Carbonate aquifers furnish industrial and municipal wells with 50 to 1,500 gal/min (3.2 to 95 L/s), and similar quantities may be available from selected sites in broad areas of Bartow County. The well water is moderately mineralized and is suitable for many industrial and other uses. Springs in the carbonate aquifers discharge 25 to 3,000 gal/min (1.6 to 189 L/s). The spring water is of good chemical quality and can be used with minimum treatment for industrial supplies. Most of the springs are unused and represent a valuable untapped resource. Well and spring pollution is widespread in the Valley and Ridge part of Bartow County. More than 20 percent of the drilled wells, 80 percent of the dug wells, and 80 percent of the large springs tested were polluted. The main causes of well polution are improper well construction and poor site selection. Many large springs are polluted because they are favorite watering places for wildlife. Similar percentages of wells and a large percentage of springs in the Piedmont part of the report area also may be polluted. 1 Barite mining in the Cartersville area left numerous open-pit mines in the residual soil of the Shady Dolomite. The Bartow County landfill occupies one of the mines, and others are being considered for landfill sites. Most of these mines are hydraulically connected with the aquifer that supplies water to the industrial wells in Cartersville. Use of the mines for disposing of solid waste possibly can contaminate large areas of this important ground-water reservoir. The Cartersville fault, generally believed to be a single thrust that crosses northwest Georgia from Tennessee to Alabama, has been found to be two thrust faults that intersect near Emerson, Bartow County: One fault extends southward from Tennessee to Emerson and is a continuation of the Great Smoky fault. The other fault trends northeastward from Alabama to Emerson, where it overrides the Great Smoky fault and continues northeastward across Lake Allatoona. To avoid confusion with the old Cartersville fault; the south-trending thrust is named the Great Smoky fault and the northeast-trending thrust is named the Emerson fault for the town of Emerson, near where it is well exposed. The eastern one-fourth of Bartow County and all of Cherokee and Forsyth Counties lie in the Piedmont physiographic province, which is underlain by a variety of crystalline rocks including schist, gneiss, amphibolite, phyllite, and quartzite of uncertain age. The availability of ground water in the crystalline rock area is highly variable. Well supplies of 2 to 25 gal/min (0.1 to 1.6 L/s) generally can be obtained in areas having low to moderate relief. In some areas of moderate relief, and in many areas of high relief, well supplies may be unavailable. Although water from a few isolated wells contains some constituents in concentrations that greatly exceed the limits set for drinking water, most well water is moderately mineralized and is satisfactory for domestic and stock use. Yields of 25 to 200 gal/min (1.6 to 13 L/s) are available from a few wells in the crystalline rocks. Yields of this size come from fault zones, zones of fracture concentration, and contact zones between rocks of contrasting character. INTRODUCTION Bartow, Cherokee, and Forsyth Counties border the Atlanta Metropolitan Area, and as a result are experiencing rapid growth in population and development. Many new industries, resort communities, and subdivisions being developed in the area need water supplies. For most, surface-water treatment is too costly and springs are either too small or inconveniently located, so nearly all of the water requirements are met by wells. The quantities needed generally range from 25 to 1,500 gal/min (L6 to 95 L/s). Developing adequate and dependable industrial and public water supplies from wells has been a problem in the three-county area for a long time. Problems arose because: (I) development sites were often acquired without first considering the availability of water, and (2) the potential yield of the water-bearing units was largely unknown prior to this study. Attempting to obtain large ground-water supplies in areas where the water-bearing units have a low yield potential resulted in costly and unproductive drilling, and ultimately in the abandonment of several developmental projects. Drilling sites that offered the greatest potential for ground-water supply were difficult to select without information about the water-bearing units. As a result, most existing large-capacity wells resulted from chance, rather than from careful site selection. Purpose and Scope The purpose of this study was to: (I) delineate all aquifers in the area: (2) determine the range of the yields of these aquifers and the chemical quality of their water: (3) map the direction of ground-water flow in the carbonate aquifers at Cartersville to determine the potential direction of movement of leachate from solid waste disposal sites: (4) measure and sample all large springs to determine their minimum annual flows and the chemical quality of the spring water: and (5) to produce geologic maps of sufficient detail to be useful in developing additional well supplies in the area. This study was designed to provide information that industries. consultants. city and county officials, land developers. and others may use to locate and develop ground-water supplies in the three-county area. In making this study. records for industrial and other high-yielding wells and a representative sample of residential and farm wells were collected to determine their depths. yields, static water levels, and types of construction. Water samples were collected from several of these wells to determine the chemical quality of water from the water-bearing units. Aquifers in Forsyth County and in eastern Cherokee County were delineated mainly from geologic maps furnished by the Georgia Geologic Survey of the Georgia Department of 1\atural Resources. The geology of most of Bartow County and western Cherokee County was mapped during this study. Water levels were measured in 100 wells and auger holes in the Cartersville area to determine the slope of the water table. Data for springs having recorded discharges of 50 gal/min or more were collected and their discharges measured to determine their approximate minimum annual flows. Samples from eight springs were analyzed to determine the chemical quality of the spring water. Surface geophysical techniques (resistivity and gravity) were used to map a highly permeable fault zone that supplies 100 to 1,500 gal/min (6.3 to 95 L/s) of water to industrial wells in Cartersville. Knowing the location of this conduit and the area that it drains is essential to the proper management of this valuable water resource. A gravity survey also was used to verify the identification of a thrust sheet in northern Bartow County. The geologic structure and, so far as possible, the hydrology of the open-pit mines in the Cartersville area were studied to determine how disposing of solid waste in the mines could affect the ground-water reservoir. The water table was contoured near the Bartow County landfill to learn the direction of ground-water movement, and to predict the probable path of leachate flow. Location and Extent of Area Bartow, Cherokee, and Forsyth Counties include an area of 1,147 mi2 (2,971 km 2) in northern Georgia (fig. I). The western part of Bartow County is in the Valley and Ridge physiographic province where the topography is dominated by north-south trending, low, generally rounded ridges and uplands, separated by both narrow and broad valleys. The uplands and higher ridges range in altitude from about 900 to I,400 ft (274 to 427 m) above sea level; valleys generally are between 700 and 800 ft (213 and 244 m) above sea level. The eastern part of Bartow County and all of Cherokee and Forsyth Counties are in the Piedmont physiographic province. The topography varies from steep, high ridges to rolling uplands and broad stream valleys. The altitude of the area ranges between 850 and 1,200 ft (259 and 366 m) above sea level. Bartow County is drained by the Etowah River and its tributaries except for the extreme northern border of the county that is drained by the Oostanaula River. All of Cherokee County and the northwest half of Forsyth County are drained by the Etowah River system. The remainder of Forsyth County is drained by the Chattahoochee River system. The counties have a mild climate. Their average January temperature is about 41 F and their average July temperature is about 77F. The average annual 2 EXPLANATION PHYSIOGRAPHIC PROVINCE ~ Valley and Ridge r:/:/:\/{] Piedmont 82' O 20 40 60 80 MILES II I I I 0'' ~~do 6~ ~0 1b0 KILOMETERS -.: Figure 1. Location of report area. 3 precipitation in the three counties is about 53 in. ( 1,350 mm). including only a small amount of snow. Rainfall in this part of the State has two peaks, one in winter and one in midsummer. separated by periods of lighter rains in spring and autumn. Autumn is the driest season of the year. Large variations can occur in the amount of rainfall received from year to year. and amounts from the wettest years may be about double those for the driest years. :'\/early half of the rainfall comes in amounts of l in. (25 mm) or more within 24 hours. Dry spells occasionally cause heavy damage to crops and pastures and result in shortages in water supplies. Droughts of this severity are, however. usually limited to rather small areas so that any given locality. on the average, is not likely to have a serious drought more often than once in 10 to 15 years. Previous StuJies Butts and Gildersleeve ( 1948) reported on the general geology and the mineral resources of the Valley and Ridge part of Bartow County. The geology and mineral resources of the Cartersville Mining District. in eastern Bartow County, were studied in detail by Kesler ( 1950). Croft ( 1963) investigated the geology and groundwater resources of Bartow County, and the generalized availability of water supplies is treated by Cressler and others ( 1976). The water resources of Cherokee and Forsyth Counties were examined by Thomson and others ( 1956). Chemical analyses of water from several wells in the report area were tabulated by Grantham and Stokes ( 1976), and summarized by Sonderegger and others ( 1978). Acknowledgements This study was made by the U.S. Geological Survey in cooperation with the Georgia Geologic Survey of the Georgia Department of Natural Resources. The Georgia Geologic Survey provided a geologic map of Cherokee County by Mr. David E. Lawton, and of Forsyth County by Dr. Joseph B. Murray, for use as a base for the ground-water study. The writers wish to acknowledge the many people in Bartow, Cherokee, and Forsyth Counties who gave assistance during this investigation. Property owners willingly supplied information about their wells and springs and permitted them to be measured and sampled. Mr. Jimmy Fowler, Fowler Well Drilling Co., Canton, Ga., furnished construction and yield data on a large number of wells in Cherokee County. Mr. Paul Helms, All Purpose Boring. Inc .. Cumming. Ga .. and his staff supplied similar data for wells in Forsyth County. Mr. John Thomas and Mr. Bob Aiken of the Lake Arrowhead resort community in Cherokee County made available comprehensive engineering reports that contained construction data. lithologic logs, electric logs, and chemical analyses for wells on the property. Mr. Pete Murray of Thompson, Weinman and Co., Cartersville, Ga., supplied information about the depth to bedrock and arranged access to company property for resistivity and gravity surveying. The contacts between the quartzite-phyllite-shale sequence and the overlying dolomite unit, and the outcrop pattern of part of the gneiss body known as Corbin Granite (Precambrian) in eastern Bartow and western Cherokee Counties, were taken from a geologic map of the Cartersville Mining District by Mr. T. L. Kesler (1950). This map, made during a period of widespread mining in the Cartersville area prior to the filling of Allatoona Lake, shows these contacts more accurately than could be determined from present exposures in the time allotted. Mr. Charles Adams and others of the Union Carbide Corp. furnished an engineering report that contained foundation boring data needed to trace the permeable fault zone beneath the industrial park in south Cartersville. They also opened unused company wells so water levels could be measured. Dr. Thomas J. Crawford of West Georgia College, working in cooperation with the Georgia Geologic Survey and the U.S. Geological Survey, supplied geologic maps and lithologic descriptions of the Piedmont part of the Burnt Hickory Ridge and Taylorsville quadrangles and parts of the Acworth and Allatoona Dam quadrangles, including the area underlain by the Corbin Granite. He also correlated the crystalline rock units south of Cartersville with ones to the east, and spent many hours discussing the lithologic relationships and the geologic structure of the Cartersville area. Dr. Crawford worked in the field with the senior author to confirm that the Cartersville fault of former usage consists of two intersecting faults (Cressler and Crawford, 1976), and agreed to name the northeast-trending fault the Emerson fault for the town of Emerson, Bartow County, near where it is well exposed. Dr. L. T. Long of the Georgia Institute of Technology planned and interpreted resistivity and gravity surveys in Bartow County to locate groundwater conduits and delineate major water-bearing units. The field work for these surveys was done by Mr. Wes Champion. Mr. Paul A. Smith, Jr., graciously furnished construction data and chemical analyses, allowed the 4 installation of water-level recorders, and permitted the use of his equipment and power to conduct an aquifer test on his property in Dawson County, adjacent to the study area. OCCURRENCE AND AVAILABILITY OF GROUND WATER Ground water in Bartow, Cherokee, and Forsyth Counties occupies joints, fractures, and other secondary openings in bedrock and pore spaces in the overlying mantle of residual soil. Water recharges the underground openings by seeping through the soil or by flowing directly into openings in exposed rock. This recharge is from precipitation that falls in the area. Unweathered and unfractured bedrock in the report area has very low porosity and permeability. Thus, the quantity of water that a rock unit can store is determined by the capacity and distribution of joints, fractures. and other types of secondary openings. The quantity of stored water that can be withdrawn by wells, or that is free to discharge from springs, depends largely on the extent to which the rock openings are interconnected. The size, spacing, and interconnection of openings differs greatly from one type of rock to another and with depth below land surface. Open joints and fractures tend to become tighter and more widely spaced with increasing depth. Joints and other openings in soft rocks such as shale and phyllite tend to be tight and poorly connected; wells and springs in rocks of this character generally have small yields. Openings in more brittle rocks such as quartzite and graywacke tend to be larger and are better connected: wells and springs in these rocks normally supply greater yields. Other rocks. including amphibolite, schist, and gneiss. are variable in the size and connection of secondary openings and generally yield small to moderate quantities of water to wells and spnngs. Carbonate rocks, which include limestone, dolomite, and marble, contain much larger and more extensively interconnected fracture systems. Openings in carbonate rocks commonly are enlarged by solution, and are capable of transmitting large quantities of water. Fractures in slate, shale, sandstone, quartzite, and similar rocks in the Valley and Ridge province area tend to be concentrated within 250 ft (76 m) of the surface. Most solution-enlarged fractures in carbonate rocks are found at depths of less than 350 ft ( l 06 m). Therefore, when drilling for water in the Valley and Ridge province, it is rarely worthwhile to drill deeper than 350 ft ( l06 m) in carbonates, or deeper than 250 ft (76 m) in other kinds of rock. If a well fails to produce the desired yield at these depths, it generally is best to try a new location. In the Piedmont area, where the rocks have been subjected to greater deformation, water-yielding joints and fractures commonly occur deeper than 400ft ( 122 m). A significant number of wells obtain water from openings about 500 ft ( 152 m) deep, and a few produce water from as deep as 700 ft (213 m). However, a comparison of drilling costs with the probability of obtaining the required yield of about 5 gal j min (0. 3 L j s) indicates that it is seldom advisable to drill deeper than about 400 ft ( 122 m) for a residential supply. Well records show that drilling deeper than about 700ft (213m) cannot be justified unless geologic evidence indicates that openings extend to greater depth. DESCRIPTION OF THE WATER-BEARING UNITS AND THEIR HYDROLOGIC PROPERTIES The report area is underlain by more than 30 different kinds of rock, many of which have similar physical properties and yield water of comparable quantity and chemical quality. Thus, for convenience, the rocks in the report area have been grouped into 10 major water-bearing units and assigned letter designations. The areal distribution of the water-bearing units is shown on the accompanying maps, plates l. 2. and 3. The physical characteristics and the hydrologic properties of each water-bearing unit are described in the following section. Because large ground-water supplies are essential to continued industrial growth in Cartersville and along the Interstate 75 corridor in eastern Bartow County, a detailed geologic map is included of that area. (See plate 4.) This map delineates the highyielding and low-yielding water-bearing units, and thus should facilitate the development of additional well supplies, especially where the underlying rock is obscured by a deep cover of soil and alluvium. Water-Bearing t:nit A Character of the rock-Unit A has the largest areal extent of any aquifer in Bartow County, but because it is generally overlain by a thick residual mantle, the bedrock rarely crops out. For this reason, its lithology is inferred from adjacent areas where it is better exposed. The bulk of the unit consists of thickly to massively bedded dolomite, mainly brown or tan in the lower part, and medium to light gray in the middle and upper parts. The unit throughout most of the county is made up of the Knox Group of Cambrian and Ordovician ages. Near Taylorsville and 5 Stilesboro, where the youngest part of the unit occurs, thick to massive layers of light- to medium-gray limestone locally account for about 50 percent of the section. The upper limestone-bearing section belongs to the :'\lewala Limestone of Ordovician age. The unit probably is between 2,500 and 3,500 ft (762 and I,070 m) thick in southwest Bartow County where the entire section is present. In the northern part of the county. the unit occupies narrow synclinal belts and probably ranges from 100 to 2,000 ft (30 to 610 m) thick. The dolomite is highly siliceous and upon weathering produces a cherty, silty, clay residuum that generally ranges from 25 to 200 ft (7.6 to 61 m) thick. The residuum is highly permeable and readily absorbs precipitation, which it holds in temporary storage and slowly releases to bedrock openings. It is this steady supply of water from the residuum that sustains the high y"ields of wells and springs in the aquifer and minimizes the adverse effects of droughts. Water-bearing character-Unit A is one of the most productive aquifers in the report area. Farm and home supplies generally are available everywhere except on steep slopes and narrow ridges. Drilled wells in the unit are very dependable and rarely decline in yield, even during periods of prolonged drought. Twenty-one wells having known yields furnish 4 to 92 gal/min (0.3 to 5.8 L/s). (See Appendix.) The chance of obtaining 5 gal/ min (0.3 L/ s) from a randomly located well in unit A, such as at most farms and homesites, is about 80 percent. In adjacent counties of northwest Georgia where more wells have been drilled in the aquifer, supplies as large as 1,500 gal/min (95 L/s) are obtained from wells in favorable locations. Selected sites in Bartow County can be expected to furnish between I00 and 1,500 gal;min (6.3 to 95 Ljs). (See the section on evaluating well sites.) Sixty-four residential and farm wells in Bartow County have an average depth of 132 ft (40 m), and their casing depths range from 35 to 134ft (II to 41 m). The shallowest well recorded is 55 ft (17 m) deep; the deepest, 331 ft (10 I m). Most wells in the unit are cased to bedrock, leaving the remainder of the well an open hole in limestone and dolomite. In areas where the depth to bedrock is greater than about 100 ft (30 m), a few wells are finished above the bedrock and derive water solely from the overlying residual soil. The soil contains permeable layers that yield 5 to 15 gal/ min (0. 3 to 0. 9 L1s) or more to wells. In developing a well in residual soil, it is common practice to drill until a water-bearing zone is reached ~nd measure the yield. If the yield is adequate, casing 1s set to total depth, leaving only the open hole in the bottom of the pipe to admit water. Thus, because of the small intake area, the full potential of the water-bearing zone rarely is utilized by this wellconstruction method. For wells that penetrate a thick layer of water-bearing material, or more than one layer, the yield generally can be increased by the use of slotted casing. This method is rarely employed, however, possibly because of increased cost. Gravelpacked wells also are successful and they commonly yield I0 to 25 gal; min (0.6 to 1.6 L; s). The chemical quality of the well water generally meets the standards set by the Georgia Department of Natural Resources (1970) and the Environmental Protection Agency (1975). (See tables I and 2.) Water from wells in bedrock is hard to very hard and most contains low concentrations of iron. Of 64 wells inventorjed, only two were reported to supply water containing objectionable amounts of iron. The iron concentration in water sampled from three bedrock wells ranged from 10 to 70 11g! L (micrograms per liter), which is fairly low. Wells that obtain water solely from the residual soil above the bedrock yield soft water that is low in iron. Well owners refer to the water as "freestone", and report that it is very good for drinking and other domestic uses. The largest springs in the report area discharge water from unit A. Fifteen springs discharge between 50 and 3,000 gal/min (3.2 and 189 L/s). The spring locations are shown in plate I, and their discharge rates are listed in table 3. Nearly all the springs are unused and represent a potentially important undeveloped resource. The spring water is hard to very hard, and most is of good chemical quality suitable for many industrial uses. With chlorination, water from some springs can be used for public and private supplies. Chemical analyses of water sampled from representative springs in Bartow County are listed in tables 2 and 4. Water-Bearing Unit C Character of the rock-Unit C consists mainly of shale, but in some areas it includes significant thicknesses of limestone, dolomite, siltstone, and sandstone. The broad belts of the unit near Adairsville, Cassville, and Pine Log are mostly greenish, gray, and slightly purplish shale that weathers to various shades of tan, pink, and orange. Scattered throughout these areas are layers and lenses of limestone and dolomite a few feet to 100 ft (30 m) or more thick. The thicker carbonate layers generally underlie narrow valleys in the shale. The unit in these areas belongs to the Conasauga Formation of Middle and Late Cambrian age. 6 Table 1. Chemical analyses of well water, Bartow, Cherokee, and Forsyth Counties. (Analyses by U.S. Geological Survey, except as noted. tr, trace) -""~- Name ...z.0...,, :< ~ " f -~1 ~ u " :l :< ...,....,, .. ~~ ~ 0 " u ~ ~ : --;:. ~ 0 ffi ~r-1 Cll 1-< e.~ riM rlrl ~-g Micrograms per liter,..... f ,..., '-' u.. 5 c'll 9 ..~.... :;..., U) '-' '-' .!:: '-' ....-! ~ oM 5 ~ -oe C ~(<) C bD ~ ..-1 Ill a"0 ...... 6:: uOntamination are located upgradient, periodic retesting commonly is desirable. GROUND-WATER POLLUTION BY LANDFILL LEACHATE Potentially, landfills could be a major source of ground-water pollution in the study area. Water percolating through landfills dissolves soluble materials, producing a leachate that may be highly charged with metal ions, organic and inorganic compounds, and pathogenic organisms.. Leachate from improperly located, constructed, and maintained landfills can contaminate both suface- and ground-water supplies. Contamination occurs as leachate enters streams or infiltrates soil and rock openings and reaches the ground-water reservoir. Bartow County Landfill Extensive barite mining in the Cartersville area left more than 20 large open pits that range from 20 to more than 100ft (6.1 to 30 m) deep. The Bartow County landfill occupies one of these mines, and several others are proposed as possible landfill sites. However, as all of the mines overlie and are hydraulically connected with water-bearing unit F, their use for solid waste disposal has the potential for contaminating substantial parts of this important ground-water reservoir. The Bartow County landfill, which has been in operation since 1967, occupies an abandoned open-pit mine on top of a high hill just east of the Cartersville city limits (fig. 3). The north and south ends of the landfill are so steep that rainfall runoff produces gully-type erosion of the cover material and during wet weather, leachate seeps from both ends. A mixture of waste material and leachate is being washed by overland runoff into the adjacent valleys that serve as recharge areas for water-bearing unit F. Thus, leachate seeping from the landfill can be a potential threat to the quality of surface water in the area of the landfill and to water recharging the ground-water reservoir. Movement of leachate overland During periods of heavy rainfall, leachate seeping from the ends of the landfill mixes with other surface runoff and is carried by intermittent streams to the Etowah River (fig. 3). The stream carrying leachate from the north end of the landfill flows east,. then south for about a mile to the river. The stream valley is underlain by a thick layer of residual soil and, provided no sinkholes develop near the channel and the residuum remains undisturbed, leachate may be years in reaching the ground-water reservoir in that area. From the south end of the landfill, leachate flows through a mined-out valley where excavation has exposed dolomite of water-bearing unit F on the valley floor, about 0.2 mi (0.3 km) downstream from the landfill. During periods of low flow, most of the water moving down the .valley disappears into the streambed just above the dolomite outcrop, and some polluted water may be recharging the aquifer through bedrock openings. Water flowing past the dolomite outcrop continues south another 0.1 mi (0.2 km) to the mouth of the valley, where the stream channel divides. During lowest flow, all the water follows the main channel along an irregular route under U.S. Highway 41, the Louisville & Nashville Railroad, and Georgia Highway 293, and finally empties into the Etowah River about 1,000 ft (305 m) east of industrial well 38. During periods of increased flow, part of the stream water follows the secondary channel westward for about 0.1 mi (0.2 km) and spills into a pond at the bottom of a large open-pit mine (fig. 3). The fact that the water level in the pond fluctuates only a few feet throughout the year and is affected very little by periods of heavy rainfall, indicates that the mine is hydraulically connected to the ground-water reservoir. Thus, pollutants reaching the pond may recharge or percolate into the ground-water reservoir. Because tracing the possible spread of leachate from the landfill site exceeded the scope of this project, no plans were included for sampling streams that drain the landfill area. However, when it was learned that the stream originating at the south end of the landfill carries leachate past bedrock exposures of water-bearing unit F and to areas where direct recharge to the aquifer is possible, samples were collected at two sites to provide background data on water quality. One sample was collected from the pond at the bottom of the large open-pit mine into which the stream sometimes empties, and another from where the stream crosses Georgia Highway 293. (See fig. 3.) The stream samples were analyzed for selected metals that commonly are concentrated in landfill leachate, and for chloride, which is a good indicator of leachate movement (U.S. Environmental Protection Agency, 1975). The analyses are listed in table 5. The analyses listed in table 5 show that the concentrations of metals and chloride in the stream samples generally are low and comparable to levels found in water from the Etowah River and from nearby wells. Thus, the presence of leachate in the stream water was not verified by these analyses. The possibility that surface pollution may be occurring 21 Table 5. Concentrations of metals and chloride in water sampled downstream from the Bartow County landfill. Sample sites t:: 0 r-1 Q) +J +J 44 () (1j 0 Q) p r--1 r--1 0 () Headwaters of stream at north end of Bartow County landfill (f~. 3)-undiluted leachate seepage.~ Pond, open-pit mine (fig. 3) .~1 03-14-75 02-28-75 Micrograms per liter ,-.. ,-.. ,-.. r--1 r--1 .<.._, .u.._, ,-.. ;::l .:..._, 13 ;::l t:: Q) .u.._, ,-.. ,-.. Q) ,.0 '1:l r-1 1-1 .~ .._, .p..._.. , Q) rJJ Q) t:: r-1 1-1 Q) (1j 13 0 p.. t:: '1:l bO ;::l = 10 >- 10 15 20 25 30 TOTAL POl NTS Example: A site with 16 points has 3 chances in 10 of yielding at least 30 gallons per minute (1.9 liters per second) and 6 chances in 10 of yielding 10 gallons per minute (0.6 Ii ters per second) Figure 9. Probability of getting a certain yield from a well at different sites having various total-point ratings. (LeGrand, 1967). POINT VAWE FOR SOIL THICKNESS POINT VALUE 0-2 2-6 6-9 9-12 12-15 CHARACTER OF SOIL AND ROCK Bare rock-almost no soil Very thin soil-some rock outcrops Soil thin-a few rock outcrops Moderately thick soil-no fresh outcrops Thick soil-no rock outcrops Figure 8. Rating in points for various conditions of soil thickness. (LeGrand, 1967) rock. The topographic and soil conditions are separately rated, and the points for each are added to get the total points which may be used in table 6 to rate a site. "Using two wells sites, A and B as examples, we can evaluate each as the potential yield of a well. Site A, a pronounced rounded upland (4-point rating for topography in figure 7) having a relatively thin soil (6-point rating for soil characteristics in figure 8), has a total of I 0 points. In table 6 the average yield for site A is 6 gpm (0.4 L/s). This site has a 65-percent chance of yielding 3 gpm (0.2 L/s) and a 40-percent chance of yielding 10 gpm (0. 6 LIs). Site B, a draw or slight sag in topography (18-point rating) having a moderately thick soil (12-point rating), has a total of 30 points, an average yield of 50 gpm (3.2 L/s). Referring to figure 9, we see that the 10-point site has less than 1 chance in 10 of yielding 40 gpm (2.5 L/s), whereas the 30-point site has better than an even chance of yielding 40 gpm (2.5 L/s). 28 Table 6. Use of numerical rating of well site to estimate the percent chance of success of a well (LeGrand, 1967). [Data are based on maximum depth of 300 feet or maximum drawdown of water level of about 200 feet. No interference from pumping is assumed. Numerical rating is obtained by adding rating in points for topography and soil thickness; gpm, gallons per minute.] Total points of a site Average yield (gpm) Chance of success, in percent, for a well to yield at least-- 3 gpm 10 gpm 25 gpm 50 gpm 75 gpm 5 2 48 18 6 2 6 3 50 20 7 3 7 3 55 25 8 3 8 4 55 30 11 3 9 5 60 35 12 4 10 6 65 40 15 5 11 7 70 43 19 7 12 9 73 46 22 10 13 11 77 50 26 12 14 12 80 52 30 14 15 14 83 54 33 16 16 16 85 57 36 18 17 17 86 60 40 20 12 18 20 87 63 45 24 15 19 23 88 66 50 25 18 20 26 89 70 52 27 20 21 28 90 72 54 30 22 22 31 91 74 56 35 24 23 34 92 76 58 38 26 24 37 92 78 60 40 29 25 39 93 80 62 43 32 26 41 93 81 64 46 36 27 43 94 82 66 48 40 28 45 95 83 68 50 42 29 46 95 84 71 53 44 30 50 96 87 73 56 47 30+ 50 97 91 75 60 50 29 From LeGrand, 196l Figure 10.- Countryside showing approximate ratings for topography. "Some topographic conditions of the region and a few topographic ratings are shown in figure I0. Wells located on concave slopes are commonly more productive than wells in convex slopes or straight slopes . Broad but slight concave slopes near saddles in gently rolling upland areas are especially good sites for potentially high-yielding wells . On the other hand , steep Y-shaped valleys of the gully type may not be especially good sites, and they should be avoided if surface drainage near the well is so poor that contamination is possible. "More difficulty is likely to occur in rating character of soil and rock than in rating topography. Everyone should be able to determine by observation if the soil is thin and if the soil is fairly thick (more than 10 soil and rock points) , but the intermediate ratings are difficult to make . If the observer is unsure of the soil and rock rating above the 6-point (thin soil) value, he may choose a 10-point value for the site with assurance that he is fairly correct. White quartz or flint is not considered a true rock in this report , because it persists in the soil zone; a quartz vein, in many cases, is considered to be a slightly favorable indication of a good well site. "The numerical rating system is not intended to be precise. One person may rate a particular site at 15 points, whereas another person may rate it at 17 points; such a small difference in rating would not be misleading. Almost everyone's rating will be within 5 points of an average rating for a site." Other factors affecting well yields Although most rocks in the Piedmont display vertical jointing, some of the more homogeneous types, such as granite and massive gneiss, exhibit a nearly horizontal jointing known as exfoliation, or sheeting. The sheeting surfaces are somewhat curved and are essentially parallel to the surface of the ground . Near the surface the sheet joints tend to be closely spaced and divide the rock into relatively thin slabs. The interval between joints increases with depth, and a few tens of feet beneath the surface the visible sheeting disappears. Experience has shown that beneath valleys and depressions the joints tend to be nearly horizontal and form excellent receptacles for collecting and storing ground water. Figure II illustrates how topography 30 plays an important role in determining well yields in this type of rock. Well "A", on top of a hill, penetrates joints that slope off toward the valley and, consequently, hold only small quantities of water. Thus, wells on hills and steep slopes are likely to have low yields and may fail during dry weather. Wells "B" and "C", on the other hand, are in a low-lying area and penetrate nearly horizontal joints that form good ground-water reservoirs. Moreover, these joints are overlain by a thick layer of saturated soil that can supply constant recharge. Wells drilled in broad, soil-covered valleys and depressions generally furnish the largest yields available in the area and are dependable throughout the year. HIGH-YIELDING WELLS High-yielding wells in the study area--ones that supply 100 to 1,500 gal/min (6.3 to 95 Ljs)-can be developed only where aquifers possess localized increases in porosity and permeability. This occurs mainly in association with certain structural and stratigraphic features, such as: (I) fault zones that produce abundant fracturing, (2) zones of fracture concentration, and (3) contact zones between rocks of contrasting character. Fault Zones Fracture zones associated with certain types of faults are very permeable and supply large quantities of water to wells and springs. Other fault zones are tight and impede ground-water circulation. A highly permeable fault zone is the principal source that supplies thousands of gallons of water per day to wells in the Cartersville Industrial Park. A gravity survey conducted as part of this study revealed that a zone of deep rock weathering extends from the center of Cartersville, southeastward beneath the industrial park to the Etowah River, and possibly beyond. Abrupt changes in gravity across the weathered zone showed that the rock on either side has a different density, and this was interpreted to mean that the deep weathering is centered along a steeply inclined fault that uplifted quartzite and shale of water-bearing unit G into contact with dolomite of water-bearing unit F. (See plates I and 4.) This interpretation was substantiated by foundation borings made in the industrial park, that revealed the underlying rock consists of highly fractured dolomite mixed with angular pieces of quartzite. Intense fracturing produced by movement along this fault created a zone of increased permeability that led to deep weathering and extensive solutioning of the dolomite. This highly permeable zone collects water from the areas in central and eastern Cartersville underlain by water-bearing unit F, and carries it southward to the Etowah River. A natural discharge point for this water was Cartersville Spring (spring 19), which went dry due to diversion of its groundwater supply with the advent of heavy pumpage in the industrial park. EXPLANATION A-Unsuccessful well B-Successful well C-Possible flowing well A -- Figure 11. Cross section of sheeted terrane showing water-filled joints in heavy dark lines. Modified from Herrick and LeGrand (1949). 31 Other steep faults in Bartow County involving carbonate rocks probably produced permeable zones that have large yield potential. The White fault that passes through the valley at Atco (plates I and 4) probably is responsible for the fracturing in waterbearing unit D that accounts for the large yields of wells 63 and 63a (plate I and. table 7). The Cassville fault created extensive brecciation of the shale through which it cut north of Ladds, and it very likely caused fracturing in the underlying dolomite of water-bearing unit D. The potential for high-yielding wells may exist along the trace of this fault. Kesler (1950) mapped several steep faults in the Cartersville area, and these are shown in plate 4. Exposures indicate that where these faults are confined to quartzite of water-bearing unit G, the associated fractures are healed by depositions of iron oxide and appear to be impermeable. However, where these .same faults project into the dolomite of water-bearing unit F, they may have produced open fractures capable of supplying large yields to wells. The traces of these faults could be located by surface geophysical techniques. Mapping done during the period of the present study revealed that the Cartersville fault, well entrenched in the literature as a single fault that crosses Georgia from Alabama to Tennessee, is in reality two intersecting faults of different character (Cressler and Crawford, 1976). The north-trending segment of the Cartersville fault, as mapped by Butts and Gildersleeve ( 1948), was found to be a continuation of the Great Smoky fault that extends into Georgia from Tennessee. The Great Smoky fault, which separates the Valley and Ridge province from the Piedmont in eastern Bartow County, is a relatively high-angle thrust that dips east at about 40 to 45 degrees. In contrast, the southwest-trending segment of the old Cartersville fault is a nearly horizontal thrust that locally dips north at a low angle. This fault, which forms the southern boundary of the Valley and Ridge province in Georgia, extends from the Alabama State line across Polk and southern Bartow Counties to a point about I mile (1.6 km) southeast of Emerson where it overlaps the Great Smoky fault. From that point the fault continues northeastward across Allatoona Lake into Cherokee County and possibly beyond. (See plate 4.) To avoid confusion with former usage, this fault is herein renamed the Emerson fault for the town of Emerson, Bartow County, near where it is well exposed. Westward movement along the Great Smoky fault resulted in intense shattering of the quartzite in water-bearing unit G. Although exposures of shattered quartzite examined during this study were cemented by iron oxide and seem to be impermeable, the healing of fractures may be less complete below the water table, leaving the quartzite a potentially important aquifer, Where the fault is in contact with dolomite of water-bearing unit F, fracturing may have created permeable zones capable of supplying large yields of wells. Northerly movement along the Emerson fault produced intense shearing in the underlying rocks, and the growth of mica on the shear planes impedes the downward movement of ground water. Wells drilled in the shear zone near the fault may have low yields. Zones of Fracture Concentration Aquifers of low to moderate productivity may yield large quantities of water to wells from localized zones of increased porosity and permeability created by the concentration of fractures. These zones of fracture concentration generally are between 30 and 200ft (9.1 and 61 m) wide. Along them the bedrock is shattered to an indefinite depth by numerous, nearly vertical, closely spaced fractures or faults of small displacement that are aligned approximately parallel to the long axis of the fracture zone (fig. 12). The zones of fracture concentration extend in straight or slightly curved lines that range in length from a few hundred feet to several miles. Straight or slightly curved linear features a mile or more long, associated with these fracture zones, are visible on aerial photographs and topographic maps and are known as lineaments. Zones of fracture concentration tend to localize valley development, especially in areas underlain by carbonate rocks, but also in other types of rock. Rock weathering is greatest along these fracture zones because they transmit large quantities of moving water. The increased chemical weathering, coupled with the erosive action of surface water, localizes the valleys over these fracture zones (fig. 13). The chances of obtaining a high-yielding well are greatest in the floors of valleys developed over a fracture zone (Parizek, 1971, p. 28-56). Valleys developed over fracture zones commonly possess distinctive characteristics that make them recognizable by their linearity on topographic maps and aerial photographs. Among the features most easily recognized are: (!) straight stream and valley segments, (2) abrupt, angular changes in valley alignment, and (3) alignment of gullies, small depressions, or sinkholes. The way some of these features appear at the land surface is shown in figure 14. The water supply for the Lake Arrowhead resort community in "northwest Cherokee County was successfully developed in rugged terrain characterized by 32 Figure 12. Zones of frac\ture concentration consist of nearly vertical closely spaced fractures. Modified from Parizek (1971). generally low-yielding wells, by drilling into zones of fracture concentration. More than 15 wells were drilled in stream valleys that topographic maps and aerial photographs indicate probably are developed over fracture zones. Drillers' logs revealed that all the wells having yields between 50 and 200 galjmin (3.2 and 13 L/s) penetrated sizable fracture systems consisting of one or more large fractures or zones of closely spaced fractures. The largest yields came from zones of closely spaced fractures. All the high-yielding wells occupy sites along straight stream segments, or where valleys make abrupt, angular change in direction. Figure 15 is a map of part of the Lake Arrowhead area showing the locations of high-yielding and low-yielding wells, to illustrate how yields relate to topographc settings. All of the high-yielding wells are in settings that strongly suggest the presence of zones of fracture concentration. As most zones of fracture concentration in that area are rather narrow-30 to 200 ft (9.1 to 61 m) wide-precision in locating wells is required to insure penetration of the water-bearing fractures. For example, wells 53 and 61 penetrate a fracture zone and yield 80 and 200 galjmin (5.0 and 13 L/s), whereas well 50, which is situated slightly off the fracture zone, penetrates mainly solid rock and yields only 13 gal/min (0.8 Ljs). The employment of aerial photographs and topographic maps to locate zones of fracture concentration resulted in six production wells that supply a combined total yield of about 560 gal/min (35 L/s). The wells are in terrane that normally supplies less than 5 gal/min (0.3 Ljs) per well. By searching out zones of fracture concentration, it should be possible to develop large ground-water supplies in most of the water-bearing units in the report area. In water-bearing units A, D, and F, which are composed of thickly to massively bedded dolomite and limestone overlain by thick residual soil, zones of fracture concentration develop into highly permeable reservoirs capable of supplying large quantities of water to wells. Such permeable zones typically underlie broad, gently sloping valleys of intermittent streams. Larger ones having catchment areas greater than 1 mi2 (2.6 km2) supply 100 to 1,500 galjmin (6.3 to 95 LIs) to wells in several areas of northwest Georgia. Similar topographic settings in Bartow County can be expected to yield comparable quantities of water to wells. Examples of the topographic expression of such valleys are shown in figure 16. Zones of fracture concentration in the more brittle types of crystalline rocks in the Piedmont also have proved to be highly productive aquifers. Wells 32 and 33 in Forsyth County derive 200 gal/min (13 Ljs) from a zone of fracture concentration that appears as 33 A ------- __f1!-AT-E-R----- -------- -----TA-B--LE--- --------- c ,"""'....,---- Original Land Surface I '-------- ---------- r-/ -"" TAE}f-_E_ __ I Dolomite ------- Figure 13. Valley development localized along zones of fracture concentration. Modified from Parizek (1971). 34 a straight valley segment on a topographic map (fig. 17). Similar straight valley segments are scattered across much of Forsyth and Cherokee Counties, and many of them may be developed over zones of fracture concentration that will supply large yields. Contact Zones Between Rocks of Contrasting Character Contact zones between rocks having different physical properties, especially in the Piedmont province, commonly are sites of concentrated fracturing and may yield large quantities of water to wells. In Forsyth County, for example, drilling records show that wells penetrate highly fractured rock when located on the lower east slope of ridges underlain by quartzite of water-bearing unit G, and near the contact with schist, gneiss, and amphibolite. Well 44, which supplies water to the city of Cumming, furnishes 150 gal/min (9.5 L/s) from fractured quartzite near the east base of Sawnee Mountain. Forsyth County wells 2 and 3 begin in schist of unit J and derive water from fractured quartzite at the contact with unit G. Yields of 20 to 200 gal/min (1.3 to 13 L/s) probably can be obtained at numerous places along the east slope of the ridges formed by unit G at the contacts with rocks of different character. The quantity of water obtainable depends largely on the size and type of catchment area that supplies recharge to the well site, on the thickness of the residual soil layer that is available to hold recharge water in storage for resupplying the fracture systems, and on the lithology of the rock units involved. Figure 14. Straight stream segments, abrupt angular changes in valley alignment, and alignment of sinkholes indicate the presence of zones of fracture concentration. 35 8437'30" Bose from U.S. Geological Survey Waleska lo24,000, 1974 0i-E-3---.---,E-3--.-----,E-3-,----------1I MILE 0, : - - , - , - , - , - , - - - - , 1 KILOMETER H H H CONTOUR INTERVAL 20 FEET DATUM IS MEAN SEA LEVEL EXPLANATION - - - - - - Z O N E OF FRACTURE CONCENTRATION 53 200 WELL-Top number refers to plate 2 and table 8. Bottom number indicates yield, in gallons per minute. Figure 15. Relation of zones of fracture concentration to well yields, Lake Arrowhead area. 36 84 52'30" Bose from U.S.Geologico I Survey Cartersville I' 24,000, 1972 OFr=-l-.--F.--3-.--E.-3-r------------~IMI ILE OEH3=:=:JHE3=:JH::::3::====:::JI KILOMETER CONTOUR INTERVAL 20 FEET DATUM IS MEAN SEA LEVEL Figure 16. Typical intermittent stream valleys in carbonate terrane, Bartow County. 37 Base from U.S. Geological Survey Birmingham 124,000, 1956 Interim revisions os of 1968 and Roswell 1=24,000, 1956 Interim revisions as of 1973 0 I MILE rF-=3--.---,F-=3--.---F--dr--T--------------~ 0rE=3-.-.E=3-.-.F3-.----------.I KILOMETER CONTOUR INTERVAL 20 FEET DATUM IS MEAN SEA LEVEL EXPLANATION - - - Z O N E OF FRACTURE CONCENTRATION ------PROBABLE ZONE OF FRACTURE CONCENTRATION e 32 200 WELL-Top number refers to plate 3 and table 9. Bottom number indicates yield, in gallons per minute. Figure 17. Permeable zones of fracture concentration commonly lie along straight valley segments. 38 CONCLUSIONS In the Valley and Ridge part of the report area, wells nearly everywhere supply water of adequate quality and quantity for domestic and farm purposes. In Bartow County, wells in water-bearing units D and F can furnish 100 to 1,500 galjmin (6.3 to 95 L/s), and yields of 50 to 1,500 galjmin (3.2 to 95 L/s) should be available from wells in selected sites in units A, D, and F. Open joints and fractures tend to become tighter and more widely spaced with increasing depth. Fractures in slate, shale, sandstone, quartzite, and similar rocks in the Valley and Ridge area tend to be concentrated within 250 ft (76 m) of the surface. Most solution-enlarged fractures in carbonate rocks are found at depths of less than 350 ft (I 06 m). Therefore, when.drilling for water in the Valley and Ridge province, it is rarely worthwhile to drill deeper than 350 ft ( 106 m) in carbonates, or deeper than 250 ft (76 m) in other kinds of rock. If a well fails to produce the desired yield at these depths, it generally is best to try a new location. Springs in water-bearing units A and D discharge 100 to 3,000 gal/min (6.3 to 189 L/s). The water is moderately mineralized and is satisfactory for many industrial and other uses. Most of the springs are unused and represent a potentially valuable untapped resource. Well and spring pollution is widespread in the Valley and Ridge part of Bartow County. More than 20 percent of the drilled wells, 80 percent of the dug wells, and 80 percent of the large springs tested were polluted. The main causes of well pollution are improper well construction and poor site selection. Many large springs are polluted because they are favorite watering places for wildlife. Similar percentages of wells and a large percentage of springs in the Piedmont part of the report area also may be polluted. Some abandoned open-pit mines in the Cartersville area of Bartow County have been used for solid waste disposal and others are being considered by local authorities for landfill development. However, the mines are hydraulically connected with underlying water-bearing unit F that supplies water to industrial wells in Cartersville. Thus, leachate from solid waste disposed of in these mines is a possible threat to contaminate large areas of this major ground-water reservoir. No leachate has been observed in the subsurface as yet, because sampling wells are not available in the critical areas. In general, ground water is available in smaller quantities in the Piedmont province than it is in the Valley and Ridge. The largest yield obtained in the crystalline rocks of eastern Bartow and in Cherokee and Forsyth Counties is 200 gal! min ( 13 L; s). Only II wells in this area are known to yield more than 50 galjmin (3.2 L/s), and most wells yield less than 15 galjmin (0.9 L/s). In some areas of moderate relief, and in many areas of high relief, well supplies adequate for residential or farm needs are either unavailable or very difficult to obtain. In the Piedmont area, where the rocks have been subjected to severe deformation, water-yielding joints and fractures commonly occur deeper than 400 ft (122 m). A significant number of wells obtain water from openings about 500 ft (!52 m) deep, and a few produce water from as deep as 700 ft (213 m). However, a comparison of drilling costs with the probability of obtaining the required yield of about 5 gal/min (0.3 Ljs) indicates that it is seldom advisable to drill deeper than about 400ft (122m) for a residential supply. Well records show that drilling deeper than about 700ft (213m) cannot be justified unless geologic evidence indicates that openings extend to greater depth. SELECTED REFERENCES Bentley, R. D., Fairley, W. M., Fields, H. H., and others, 1966, The Cartersville fault problem: Guidebook No. 4, Georgia Geological Survey, 38 p. Brunner, D. R., and Keller, D. J., 1972, Sanitary landfill design and operation: U.S. Environmental Protection Agency, Solid Waste Management series SW-65ts, 59 p. Butts, Charles, and Gildersleeve, Benjamin, 1948, Geology and mineral resources of the Paleozoic area in northwest Georgia: Georgia Geological Survey Bulletin 54, 176 p., 8 pis. Crawford, T. J., and Medlin, J. H., 1970, Stratigraphic and structural features between the Cartersville and Brevard fault zones: Guidebook, 5th Annual Field Trip, Georgia Geological Society, 37 p. Cressler, C. W., 1963, Geology and ground-water resources of Catoosa County, Georgia: Georgia Geological Survey Information Circular 28, 19 p. __!964a, Geology and ground-water resources of the Paleozoic rock area, Chattooga County, Georgia: Georgia Geological Survey Information Circular 27, 14 p. __ l964b, Geology and ground-water resources of Walker County, Georgia: Georgia Geological Survey Information Circular 29, 15 p. __ 1970, Geology and ground-water resources of Floyd and Polk Counties, Georgia: Georgia Geological Survey Information Circular 39, 95 p. 39 __ 1974. Geology and ground-water resources of Gordon. Whitfield. and :vturray Counties. Georgia: Georgia Geological Suney Information Cir- cular 47. 56 p. Cressler. C. W .. and Crawford, T. L 1976, Carters- \ille fault found to be two intersecting thrusts, in Geological Suney Research 1976: U.S. Geological Suney Professional Paper 1000. 414 p. Cressler. C. W .. Franklin. M. A., and Hester, W. G., 1976. Availability of water supplies in northwest Georgia: Georgia Geological Suney Bulletin 91, 140 p. Crickmay. G. W .. 1952. Geology of the crystalline rocks of Georgia: Georgia Geological Survey Bulletin 5X. 54 p. Croft. M.G .. 1963. Geology and ground-water re,ource' of Bartow County, Georgia: U.S. Geolog1cal Survey Water-Supply Paper 1619-FF. 32 p. __ !964. Geology and ground-water resources of Dade County. Georgia: Georgia Geological Survey Information Circular 26. 17 p. D-< i~!( . . : .. . .\,_,. . .. . . . . ,f : .\ -. t A :, ' ' . I ., \ ; . '/: . J' . ' I"; ' I ' 1: ,, 1f:.. . .J .. ' . . . . r - ~.~-< ':_ _ ~149 . ~ ~ '\. \ 'J'>-' ........ _, _ .': ~~~: . . ) f b ' j - .. - -. . . ..... ; >.:. . " J . .. . "\~{~ ~__.;X"!" . . 1531 ... .,. .. .. . ... \.. .. . .~ ) '11:: :j I I I' :.. "<'- --- 7j > / ( I Base from U S. Geolog1COI Survey Greater Atlanta Reg1on I 1000,0001 1974 A No vert1cal exaggeration OC=~C:E3C:~==:j2~~~~3=======J4~~~~5=======6~~~~7t=====;=J8MILES OCJ~ft====2~~~3t====4~~~5t====6~~37C:::=8~~~9::::JIO~~II.KILOMETERS Prepared in cooperation w1th the UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY INFORM ATION CI RCULAR 50 PLA T E I 1. '7- [I '' _j ' Geology by C W Cressler E X PLANA TI ON ' I \ \',( ' "' j \ ,._jl '-,. J rI I ( f' ',t,r\ \ ' 1) -----3422 30" JASPEROID--Concentrations of large blocks that may interfere with well drilling. L~ Ad YIELD--Wells yield from 4 to 92 gal/min (0.3 to 5 . 9 L/s). Farm and home supplies are readily available, as randomly located wells have about an 80 percent chance of yielding 5 gal/min (0 . 3 L/s) , Yields as large as 1,000 gal/min (63 L/s) should be obtainable at favorable sites in A, and as large as 1,500 gal/min (9.5 L/s) in Al Fourteen springs have minimum annual discharges of 50 to 3,000 gal/min (3.2 to 189 L/s), and most are unused. DEPTH--Wells range in dept~ from 55 to 331 feet (17 to 101m), and average 132 feet (40 m) deep. QUALITY--The well and spring water is moderately mineralized, meets the drinking-water standards, and is suitable for many industrial us;es . Water from wells in bedrock and from springs is hard to very hard . Water from wells in residuum is soft. ROCK TYPE--The unit consists of thickly to massively bedded brown and gray dolomite (A), and gray dolomite inter layered with tan and gray limestone at the top (A 1). GEOLOGIC HAZARDS--Danger of ground collapse near centers of heavy pumpage is moderate to high . Likelihood of well and spring pollution resulting from contaminants entering sinkholes is very high . GEOLOGIC CORRELATION--Includes Knox Group (Cambrian and Ordovician age) and overlying Newala Limestone (Ordovician age) at the top. 'l---15' YIELD--Most wells yield between 2 and 15 gal/min (0 . 1 and 0 . 9 L/s). Farm and home supplies generally can be obtained without difficulty in flat lying and gently sloping areas, but essentially dry wells are reported on steep slopes and higher elevations. Ran- domly loc.ated wells probably have less than a 60 percent chanc.e of yielding 5 gal/min (0 . 3 L/s) . Yields as large as 70 gal/min (4,4 L/s) have been obtained from thick layers of limestone within the unit. DEPTH--Wells range in depth from 50 to 558 feet (15 to 170m), and average 182 feet (55 m) deep . QUALITY--Water from most wells meets drinking-water standards, although some constituents approach the upper limits. The water varies from soft to very hard, and most contains low concentrations of iron, Water from a few wells contains hydrogen sulfide and has the odor of rot ten eggs. ROCK TYPE--The unit is mainly shale, but locally includes sections of limestone and dolomite 10 to 50 feet (3 to 15 m) or more thick . In the eastern outcrop belt, the shale is interlayered with sandstone and thinly layered dolomite . GEOLOGIC HAZARDS--Danger of ground collapse near wells is small except for ones in thick limestone sec.tions, where the danger is low to moderate. GEOLOGIC CORRELATION--Includes predominantly shale parts of Conasauga Formation and the Rome Formation (Cambrian age); Rockmart Slate (Ordovic.ian age). YIELD--Wells yield from 5 to 200 gal/min (0 .3 to 13 L/s). Yields as large as 300 gal/min (19 L/s) may be obtained at favorable sites. Do1mestic and farm supplies are available nearly everywhere; randmmly located wells have about an 80 perc.ent chance of yielding 5 gal/min (0.3 L/s) . Three springs have minimum annual disc.harges of 18 to 150 gal/min (0 . 5 to 9.5 L/s) and the water is largely unused. DEPTH--Thirty-four wells range in depth from 30 to 150 feet (9 to 46 m) and average 181 feet (55 m) deep . QUALITY--The well and spring water is hard to very hard, generally contains low concentrations of iron and other dissolved constituents, and is suitable for most uses. ROCK TYPE--The unit is mainly thinly to massively bedded gray and brown dolomite, but it commonly includes layers of limestone and locally c.ontains thick units of gray limestone. GEOLOGIC HAZARDS--Danger of ground collapse near c.enters of heavy pumpage is moderate to high . Well and spring pollution may result from c.ontaminants entering the ground through sinkholes. GEOLOGIC CORRELATION--Includes dolomite and limestone facies of the Maynardville Limestone Member of the Conasauga Formation, units of the Conasauga Fo rmation composed mainly of limestone, and the lower dolomite unit of the Conasauga Formation (Cambrian age) . YIELD--The unit is the principal source of industrial water supply in Cartersville. Seven industrial wells yield from 150 to J ,000 gal/min (9 . 5 to 189 L/s). Farm and home supplies probably can be developed without difficulty in most of the outcrop area . DEPTH--The wells range in depth from 80 to 300 feet (24 to 91 m), and average 158 feet (48 m) deep . QUALITY--The well water is moderately hard to hard and c.ontains small concentrations of iron and most other constituents. The water is suitable for drinking and for many industrial uses. ROCK TYPE--The unit consists of thinly to massively bedded light- to dark-gray dolomite that contains thin layers and laminations of pink and silver phyllite in the upper part. The dolomite is siliceous and yields abundant Jasperoid , GEOLOGIC HAZARDS--Danger of ground collapse near centers of heavy pumpage is high. Likelihood of pollution resulting from contaminants entering the ground through sinkholes or through the bottom of open pit mines is very high . GEOLOGIC CORRELATION--Includes Shady Dolomite (Cambrian age). r . .r=-r----' 'lI , I ~ I CRESSLER, 1976 ' I IL' - ~::_CR--A-W-~--~-'9,~j1, INDEX TO GEOLOGIC MAPPING YIELD--In the few areas level enough for farming and home construction 1 wells generally supply between 2 and 10 gal/min (0.1 and 0.6 L/!s) . On steep slopes, narrow-crested ridges. and scarp slopes, well supplies normally are unavailable . Yields as large as 200 gal/min (13 L/s) c.an be developed at selected sites where wells penetrate fracture zones in quartzite that are recharged by large catchment areas . Fifteen wells drilled in frac.ture zones have an average yield of 60 gal/min (3.8 L/s), but such sites are widely scattered and are absent in some areas. DEPTH--Wells range in depth from 92 to 330 feet (28 to 101 m), and have an average depth of 241 feet (73 m). QUALITY--The well water ranges from soft to hard, generally contains low to moderate c.oncentrations of iron, and is suitable for drinking and many other purposes. ROCK TYPE--The unit consists of interlayered quartzite and phyllite . The quartzite is thinly to massively bedded, fine to coarse grained, commonly feldspathic, locally conglomeratic, and varies from very light gray to dark gray. The phyllite varies from light gray to nearly black and occurs in layers a few inches to several feet thick . Muc.h of the phyllite east of the Great Smoky fault weathers to a distinctive copper color , In some areas (G), quartzite is the predominant rock type; in others (G 1) , phyllite is more abundant . GEOLOGIC CORRELATION--Inc.ludes Chilhowee Croup (Cambrian age) and Ocoee Supergroup (Precambrian). 'ilELD--Wells supply between 1.5 and 25 gal/min (0 . 09 and 1.6 L/s) . The largest yield that can be expected from the unit is about 30 gal/min (2 L/s). Randomly located wells probably have less than a 40 percent chance of supplying 5 gal/min (0 . 3 L/s) . DEPTH--Wells range in depth from 86 to 450 feet (26 to 137 m) . All the wells that supply 5 gal/min (0.3 L/s) or more are shallower than 166 feet (51 m). The casing in most wells is between 29 and 85 feet (8 . 8 and 26 m) deep . QUALITY--The well water generally is soft and has a low concentration of total dissolved solids . Much of the water has a pH of less than 7.0 and may corrode plumbing. The concentration of iron in four wells sampled ranged from 0 to 250 ~g/L, which is within the limits set for drinking water. Water from part of the unit contains hydrogen sulfide and reportedly has the odor of rotten eggs . ROCK TYPE--The unit consists mainly of phyllite and schist, some of which is dark c.olored and graphitic. Layers of quartzite and graywacke are common in some areas, and locally form ledges and low ridges. ~ ~ YIELD--Wells yield between 2 and 35 gal/min (0.1 and 2.2 L/s) . Domestic and farm wells can be developed nearly everywhere and public supplies of 20 gal/min (1 . 2 L/s) are common . Yields of 15 to 20 gal/min (0.9 to 1.3 L/s) can be expected from favorable sites . Randomly loc.ated wells probably have about a 60 percent chanc.e of furnishing 5 gal/min (0.3 L/s). DEPTH--Inventoried wells range between 40 and 500 feet (12 to 152 m) deep, for an average depth of about 155 feet (47 m) , About 90 percent of the wells are less than 250 feet (76 m) deep . Casing ranges from as little as 5 feet (2 m) to as much as 130 feet (40 m). QUALITY--The water is soft and reported to be good for household use The concentration of iron in most well water is low, although water from two wells contained 280 and 450 ~g/L of iron. ROCK TYPE--The unit is c.omposed chiefly of gneiss, including augen gneiss, granite gneiss, and biotite gneiss . The rock varies from massive to highly sheared. GEOLOGIC CORRELATION--Includes Corbin Granite (Precambrian) in western outcrops . YIELD--Most existing wells yield only enough water for domestic or farm supply. The largest yield known in the unit is 32 gal/min (2 L/s). Larger than average yields should be the rule in parts of the unit that contains brittle rock (Lt). Randomly loc.ated wells have about a 40 percent chance of yielding 5 gal/min (0.3 L/s). DEPTH--The wells range from 62 to 400 feet (19 to 122 m) deep, and average about 160 feet (49 m) deep. They are cased from 15 to 112 feet (5 to 34 m) deep. QUALITY--The water generally is soft, and most contains low concentrations of iron and other constituents. ROCK TYPE--The unit consists mainly of seric.ite and quartz-muscovite schist and interlayered metagraywacke (L). Quartzite in layers 10 to 30 feet (3 to 9 m) thick, and graywac.ke in layers of similar thickness, make up a significant part of the section in northern Cherokee County (Ll). YIELD--The unit is used almost exclusively for domestic and farm supplies. Wells generally furnish less than 15 gal/min (0 . 9 L/s) , Randomly located wells have about a 40 percent c.hance of supplying 5 gal/min (0 . 3 L/s) . Three wells in the unit supply 200 gal/min (13 L/s), apparently from highly per mea ble zones produced by intense fracturing of the brittle rock . Two of the wells are along a linement, probably developed on a zone of fracture concentration. DEPTH--Wells range in depth from SO to 532 feet (15 to 162m), and average about 137 feet (42 m) deep . The depth of casing in most wells is between 30 and 100 feet (9 and 30m) . QUALITY--The water is soft to moderately hard, contains low concentrations . of iron, and generally is satisfactory for domestic use. ROCK TYPE--The unit in Cherokee County consists mainly of hornblende gneiss and schist interlayered with amphibolite . In Forsyth County it is mainly amphibolite . CONTACT--Approximately located; dotted where concealed . ~- * - ?. FAULT--Approximately located; dotted where inferred; queried where doubtful. ~. upthrown side; D, downthrown side; T, upper plate, 60 e WELL AND IDENTIFICATION NUMBER 54 C>- SPRING AND IDENTIFICATION NUMBER A' ,00 SEA LEVEL ,00 1000 1>00 WATER-BEARING UNITS AND LOCATIONS OF SELECTED WELLS AND SPRINGS, BARTOW COUNTY, GEORGIA. GEORGIA DEPARTMENT OF NATURAL RESOURCES GEORGIA GEOLOG I C SURVEY Prepared in cooperat ion with the U NI TED STATES DEPARTMENT OF THE INTERIOR GEOLOG ICAL SURVEY s4 ool Ge olog y by J. B.Murry , 1973 a4oo' Bose from U. S. Ge ol og ica l Survey Greoter At lonto Reg ion 1:100 ,000, D FEET 2000 1000 SEA LEVEL HIGH TOWER No ver t ica l exaggeration 7'30" 2 2 3 3 4 5 4 5 6 3 7 8 9 10 SAW NEE MOUNTAIN J o' METERS 2000 :500 10 0 0 SEA LEV EL SEA LEVEL 1000 2000 500 3000 4000 1000 50 0 0 1:500 INFORMATION C IRCULAR 50 PLATE 3 E X p L A NA T 0 N YIELD--In the few areas level enough for farming and home const ruction , wells generally supply between 2 and 10 gal/min (0 . 1 and 0 . 6 L/s) . On steep slopes , nar r ow-crested ridges, and scarp slope s, well supplies normally are unavailable . Yields as large as 200 gal/min (13 L/s) can be developed at selected sites where wells penetra t e fracture zones in quartzite that are recharged by large catchment areas. Fifteen wells drilled in fractu r e zones have an average yield of 60 gal/min (3 . 8 L/s), but such sites are widely scatte red and are absent in some areas . DEPTH--Wells range in depth from 92 to 330 feet (28 to 101 m) , and have an average depth of 241 feet (73 m) . QUALITY--The well wate r r anges from soft to hard , gene r ally con t ains low to mode r a t e concentrations of iron, and is suitable for d r inking and many other purposes . ROCK TYPE--The unit consists of interlayered quartzite and phyllite . The quartzite is thinly to massively bedded, fine to coarse grained, commonly feldspathic, locally conglomeratic , and varies from very light gray to dark gray . The phyllite varies from light gray to nearly black and occurs in layers a few inches to several feet t hick . Much of the phyllite east of the Great Smoky fault weathers to a distinc t ive copper color . In some ar eas (G) , quartzite is the predominant rock type; in others (GJ), phyllite is more ab undant . GEOLOGIC CORRELATION--Includes Chilhowee Group (Cambrian age) and Ocoee Supe r~o up (P r ecamb r ian). YIELD--Wells supply between 1 . 5 and 25 gal/min (0 . 09 and 1 . 6 L/s) . Th e largest yield that can be expected f r om the unit is abo ut 30 gal/min (2 L/s) , Randomly located wells probably have less than a 40 percent chance of supplying 5 gal/min (0 . 3 L/s) . DEPTH--Wells range in depth from 86 to 450 feet (26 t o 137m) . All the wells that s upply 5 gal/min (0 . 3 L/s) or more are shallower than 166 feet (51 m) . The casing in most wells is between 29 and 85 feet (8 . 8 and 26 m) deep . QUALITY--The well wate r gener ally is soft and has a low concentration of total dissolved solids . Much of the water has a pH of l ess t han 7 . 0 and may corrode plumbing . The concentration of iron in four wells sampled ranged f r om 0 to 250 ~g/L , which is within t he limits set for drinking water. Water from part of the unit contains hydrogen sulfide and reportedly has t he odor of ro t ten eggs . ROCK TYPE-- The unit consists mainly of phyllite and schist , some of which is dark colored and graphitic . Layers of qua r tzite and graywacke are common in some areas , and locally fo r m le dges and low ridges . L~ 2iJ YIELD--Wells yield between 2 and 35 gal/min (0 . 1 and 2.2 L/s) . Domes t ic and farm wells can be developed ne.trly everywhere and public sup- plies of 20 gal/min (1.2 L/s) a r e common . Yields 'of 15 t o 20 gal/min (0 . 9 to 1.3 L/s) can be expected from favorable sites . Randomly located wells probably have about a 60 percent chance of furnishing 5 gal/min (0 . 3 L/s). DEPTH-- Inventoried wells range between 40 and 500 feet (12 to 152 m) deep, for an average depth of about 155 feet (47 m) . About 90 percent of the wells are less than 250 feet (76 m) deep . Casing ranges from as little as 5 feet (2 m) to as much as 130 fee t (40 m) . QUALITY--The water is sof t and reported to be good for household use . The concentration of iron in most well water is low, alt hough water from two wells contained 280 and 450 ~g/L of i r on . ROCK !YPE--The unit is composed chiefly of gneiss , including augen gneiss , granite gneiss , and biotite gneiss. The rock varies from massive to highly sheared . GEOLOGIC CORRELATION--Includes Corbin Granite (Precambrian) in western outcrops . YIELD--Most existing wells yield only enough water for domestic or fa r m supply , The largest yield known in the unit is 32 gal/min (2 L/s) . Larger than average yields should be the rule in par t s of the unit that contains brittle rock (L 1 ) . Randomly loca t e d wells have abo ut a 40 percent chance of yielding 5 gal/min (0 . 3 L/s) . DEPTH--The wells range from 62 to 400 feet (19 to 122 m) deep , and average about 160 feet (49 m) deep . They a r e cased f r om 15 t o ll2 feet (5 to 34 m) deep . QUALITY--The water generally is soft, and most contains low concen t rations of iron and o t he r constituents . ROCK TYPE- -The udit consists mainly of sericite and qua rt z- muscovite schist and inte r layered metag raywacke (L) . Qua r tzi t e in layers 10 to 30 feet (3 to 9 m) thick , and graywacke in layers of similar thickness, make up a significant par t of the section in nort hern Cherokee County (Ll) . YIELD--The unit is used almost exclusively for domestic and fa r m supplies . Wells gene r ally furnish less t han 15 gal/min (0 . 9 L/ s) Randomly located wells have about a 40 percent chance of su pplying 5 gal/min (0 . 3 L/s) . Three wells in t he unit sup ply 200 gal/min (13 L/s), apparently from highly permeable zones pr oduced by intense fracturing of the brittle rock . Two of the wells a r e along a linement , probably developed on a zone of f r act ur e concentration . DEPTH--Wells range in depth from 50 to 532 feet (15 to 162m) , and average about 137 feet (42 m) deep . The dep t h of casing in most wells is between 30 and 100 feet (9 and 30m) . QUALITY--The water is soft to moderately hard , contains low concentrations of i r on, and generally is satisfactory for domestic use . ROCK rYPE--The unit in Cherokee County consists mainly of hornble nde gneiss and schist interlayered wi t h amphibolite . In Forsyth County it is mainly amphibolite . YIELD--Well yields range from 0 to 90 gal/min (0 to 6 L/s) . Although domestic supplies can be obtained from most of the area, some "dry" holes are reported, and several very deep wells supply minimal quantities . Less than 5 gal/min (0 . 3 L/s) is supplied by 19 percent of the wells inventoried, Randomly loca t ed wells have about a 60 percent chance of yielding 5 gal/min (0 . 3 L/s) . DEPTH--Wells range in depth from 68 to 985 feet (21 to 300m) , averaging 352 feet (170m) . QUALITY--The water is soft and contains small concen t rations of iron . It is mode r ately mineralized and is sui t able for most uses . ROCK TYPE .--The unit consists of ho r nblende gneiss , biotite gneiss , mica schist, and amphibolite interlayered in varying thicknesses an d proportions . The rocks are inclined and most wells deri ve wate r from two or mo r e kinds of rock . The unit probably is hun dreds , if not thousands, of feet thick. 24 CONTACT--Approximately located WELL AND IDENTIFICATION NUMBER WATER-BEARING UNITS AND LOCATIONS OF SELECTED WELLS, FORSYTH COUNTY, GEORGIA . GEORGIA DEPARTMENT OF NATURAL RESOURCES GEORG IA GEOLOGIC SURVEY 84 4 7'30" Prepared in cooperation wi th the UNITED STATES DEPARTMENT OF THE INTER I OR GEOLOG I CAL SURVEY INFORMAT I ON CIRCULAR 50 PLATE 5 Bose from US. Geological Survey Cartersville 1=24,000 , 1972, Burnt Hi ckory Ridge 1=24,000 , 1972 Allotoono Dam 1=24,000, 196 1, i nter i m rev i s1on as of 1968, and Ac..,orth 1=24,000, 1956, i nter im rev1s i on as of 1I~ 968==~==~ 71 ==~==~==~~~~~~~~~~I MILE IOOOEJ=:El=:EO==::::JIOOOE=='E=='=:J2000==3::l000=:===:==4=r000==5000::EOE=='=6000=r:===7000 FEET 0 I KILO METER ~~~======~~~~~~ CO N TOU R IN T ER VAL 20 F EET DATU M IS M EA N SE A LEVEL EXPLANAT ON 1::/x1AREA OF LARGE OPEN-PIT MINES ------~~ DIRECTION THAT LEACHATE GENERATED IN THE MINES CAN BE EXPECTED TO MOVE ~ AREA OF POSSIBLE CONTAMINATION BY LEACHATE ~ GENERATED IN THE OPEN-PIT MINES, AT 1976 DOWN THE 1976 WATER-TABLE SLOPE WATER- TABLE SLOPE OPEN-PIT MINES IN THE CARTERSVILLE AREA LARGE ENOUGH TO BE POTENTIAL LANDFILL SITES . GEGR G A GEORG A A R SO R CES 88se lfom e818GIE8 1 9 rvey ; e8!er A l8 n 8 ~eg l o n I loo, ()0(), I 74 B ~CG ~ ~ 0 ~ \J J ~ l1t /Iili' E I c , pi\,. \ rt~kr~' ln\ dletr./ ' .:. . .... . .... .. ~ .. ... ~ : .. . : ~ . : , : : : .- . ~ ..:.::.'" ' ' .., Flre pare In coo peF ion wl t e ITED STATE DEPA RTME T OFT E I T R GR GEO OG CAL sl.JR VEY w eSI8gy 'y c Cress ler, D T eraw 6 7 6 INFORMATI ON CI RCU LAR 5 0 PLAT E 2 E X p A AT 0 N r w 5 E8 28!i gal/min (0 . 3 to 13 L/s), Yields as a /m n (1 L/s) may be obtained at favorable sites . f rm sUPp s are available nea r ly everywhere ; ran - about an 80 percent chance of yielding 5 of 18 to 150 and the water is largely unused , ran e ln depth f r om 30 to 150 feet (9 to 46 m) ~ 5 m) deep. is ha r d to very hard , gene r ally con dissolved constitu- Seii. 'Maynadlv ~ c 1 wer ~ Y EL K n riL fracture zones have an such sites are widely 101 m), and have rom soft to hard , generally contains low is suitable for dr tnking In type ; in others Group (Cambrian age) and Ocoee The YiE DEPT R8eK: soft and has a low concentration of of the water has a pH of less than ns ~ mkinly of phylli t e and schist , some of re& n& gr aphitic . Layers of qua rt zite and mmBn 1R ~orne areas , and locally form ledges and (12 to 152 m) m) . About 90 feet use . in western 6 7 N CONTA T- -A ppr 8* rna e y E Ee u - =I -D- ?. .. t~~ wtl re l': nee eS e wlier R erre : ~ rS ~ !l , Bwn- - =t- -- gy 8 n ----,--- 1BE Ee 9w tr 8 u It 1 ne ' d - --t+- -- G 8 vEdRTr UeRc NEBBnS8YNLINpE -s-f SR 1 w!n mbs R L 3:3 WE AN~ I E .TIFI AT I B' ETERS c' deep , and averThey are cased from 15 to 112 low concentra- nly of se r icite and quartz- muscovite ye r~ metag r aywacke (L) . Quartzite in laye r s m) thick , and graywacke in layers of sirni e ' ~ a significant part of the section in (Ll) . YIE xclusively for domestic and farm sup- Bfl T se f r acture con- r Bm 50 to 532 feet (15 to 162m), and aver( 4 m ) deep . The depth of casing in most ~nd lao feet (9 and 30 m) . o mo der ately hard, contains low concentra - 8n aRa genera ll y is sa t isfactory fo r domestic use . 10 ~He r8 kee County consis t s mainly of hornblende n8 s f fi S i n e r l aye r ed with amphibolite . In Forsyth ~ is Rl y m bolite . 6 L/s) . Although of the area , some EPT -- ReK averaging Eon tain s sma ll concen tr a ti ons of i ron . 1 zed and is suitable fo r most uses . Bf ho r nblende gneiss , biotite gneiss, mica nt e r laye r ed in va r ying t hicknesses and r e inc l ined and most wells derive water Bf rock . The unit probably is hund r eds, t hick. WAT ER- BE ARIN G UN IT S AND L OCAT IONS OF SELECTED WE6L3, CHEROKEE CO UN T Y, GEORGIA.