Ground-water resources and geology of Rockdale County, Georgia

IC 33 GEORGIA
STATE DIVISION OF CONSERVATION
DEPARTMENT OF MINES, MINING AND GEOLOGY A. S. FURCRON, Director
THE GEOLOGICAL SURVEY
Information Circular 33
GROUND-WATER RESOURCES AND GEOLOGY OF
ROCKDALE COUNTY, GEORGIA
By M. J. McCollum
U.S. Geological Survey
Prepared in cooperation with the U.S. Geological Survey
ATLANTA
1966

. I

CONTENTS
Page

Abstract ---------------------------------------------------------------------------------------------------------------------------------------------------------------- 2

Introduction ---------------------------------------------------------------------------------------------------------------------------------------------------------- 2

Previous work _

--------- -- - - - - - - - - - - - -- -------- - - - ---- - -- 2

Acknowledgments __

_

----- -- - - - -- ---

3

Well-numbering system - - -----

-- --------- - - - - - - - ------ - - 3

Geology -~--

__

-- - --- - - --- - - -- - -- - - - 3

Lithonia Gneiss of Watson (1902) - - - -- -- -- -

_______ _ 3

Rock description____________________________________________________________________________________________________________________________________ 3

Water-bearing characteristics ___________ ------------------------------------------------------------------------------------------------ 4

Garnet mica schist

4

Rock description -- - ---- - - -----------

------ - --- -- - -- - - -- - 4

Water-bearing characteristics

_

- - ---- - - -- - - ---- - 4

Muscovite quartzite ------------------------------------------------------------------------------------------------------------------------------------- 4

Rock descl'iption ___

----- - -- - -- --

4

Water-bearing characteristics

----- --- -----

4

Porphyroblastic biotite gneiss

------ - - - --- -- - - - - - - -- -- - 5

Rock descript ion - - -- - ---- - --

---------- - ---- - -- - - - - - -- 5

Water-bearing characteristics _ _____ _

5

Amphibolite gneiss ~-

-- - - - - - - -- - - --- -- - -

5

Rock description ---------------------------~ -

5

Wa.t er-beru:ing characteristics ----------

-- -- - - - -----

5

Panola Granite of Herrmann (1954)

5

Rock des cription -- - - - - -- ---- - --- - - - -- -

5

Water-bearing characteristics - - -- - ------- - - -

5

P egmatite ---------------------------------------------------------------------------------------------------------------------------------------------------- 5 Rock description _________________---------------------------------------------------------------------------------------------------------------- 5

Water-bearing characteristics---------------------------------------------------------------

6

Diabase dikes --------------------------------------------------------------------------------------------------------------------------------------------- 6

Rock description - - - - - - - ----

----------- - - ---------------- 6

Water-bearing characteristics - - - --- ---

6

Alluvium

---- - -- - - -- ----------

6

Rock description -- - - - - - -- - - - - - - - - - -- -- - - - -- ------

6

Water-bearing characteristics________________ _____

6

Ground water ------------------------------------------------------------------------------------------------------------------------------------------------ 6

Occurrence - -- - - -Discharge and recharge Well construction _ __ _

7

-- - - - - ---

7

8

Yield of wells _________

-- ----------

8

Surface water --------------------------------------------------- _______----------------------------------------

8

Water quality - - ------Water consumption

-- - - -- 8

-

------ - -- -- - - - - 10

Conclusions -------------------------------------------------------------------------------------------------------------- - - - -- - -

10

Record of springs and wells

-

10

Selected references - - - - - - - ---- - - - - - - - - - - ------------ - - - - - - - -- - --- 10

Plate

ILLUSTRATIONS
Page 1. Maapnodf sRporcinkgdsale___C___o__u__n__t__y__,___G__e__o___r_g__i_a____s_h___o__w__i__n__g__.g.__e__o__l_o__g__y___a___n__d___l_o_c__a__t_i__o__n___o__f___w___e_l_l__s_______________________Pocket

Figure 1. Index map of Georgia showing location of Rockdale County ------ - - - - - - - - - 2

2. Occurrence of ground water in nonlayered rocks ---- __ ______

------------------- 6

3. Occurrence of ground water in layered rocks - - - - - -- - -- -- - - - - - - - - - -- 7

4. Construction of bored, dug, and drilled wells - ----- - --

-------- 8

Table

TABLES

1. Recommended minimum standards of water quality ------- - ___ - - --

2. Chemical analyses of ground water and of Conyers surface-water supply,

Rockdale County _ __ _ ____ ------ ------- - - -

_______ ____ 3.
4.

Record Record

of of

springs in Rockdale County _____ wells in Rockdale County_________

- - - - --

- - - -.. - -

1

Page ------ --- 9
9 _ _ _ 1112

GROUND-WATER RESOURCES AND GEOLOGY OF ROCKDALE COUNTY, GEORGIA

M. J. McCollum

ABSTRACT
Rockdale County is located in the Piedmont area of Geort.ria about 20 miles east of Atlanta. Six major geologic units- Lithonia Gneiss of Watson (1902), garnet mica schist, muscovite quartzite, amphibolite gneiss, porphyroblastic biotite gneiss, and Panola Granite of Herrmann (1954) have been mapped. Diabase dikes strilting N. 30 W. toN. 45 W. occur in the northern part of the county. All rock units ru:e intruded by nonmappable pegmatite dikes and quartz veins. Only one pegmatite of mappable size was found. It occurs in the southern part of the county. A mantle of saprolite overlies all rock types.

as

a

35" \ - - - - --+--- -....-+

\Ron~
I
,...,..- - t - - --4----t-----'(

Ground water occurs in the pore spaces of the saprolite and in the cracks and crevices of the un-
weathered bedrock Water for rural use is supplied from dug, drilled, and bored wells. The yield of wells is usually greater on hillsides and in valleys than on hilltops.

Treated surface water from Yellow River is supplied to residents of Conyers and Milstead and to industries in the vicinity of Conyers from the Conyers Water Treatment Plant.
The chemical quality of ground water throughout Rockdale County is generally good. However, a high iron content is reported in water from isolated areas underlain by almost all rock types, but most predominantly in the southern part of the county in areas underlain by porphyroblastic biotit e gneiss.
Total water consumption in Rockdale County during 1964 has been estimated at 776,000 gallons per day. This includes 225,000 gallons of ground water and 551,000 gallons of surface water.
INTRODUCTION
Rockdale County, located about 20 miles east of Atlanta, is undergoing rapid change from a l'ural to an 1.rrban economy. Although the county is mall in size, 128 square miles in area, its situation is such t hat it will develop bot h industrially and residentially as the Atlanta Metropolitan a1ea expands. (See fig. 1.) Before such development can take place, however, one prerequisite must be met; an adequate water supply.
The purpose of this report is to summarize the present water supply in Rockdale County and to relate the occurrence of ground water to the geology of the area, thereby indicating the potential water resources for future needs.
The total population of Rockdale County in the 1960 census was 10,600 and since then it has

"..'......_.........._._

- 8l" -----,!
_ . __ _-,JJ MIU .! 82,.

Figure 1.-Index map of Georgia showing location .of Rockdale County.
grown to almost 14,000. Conyers and Milstead are the only towns in the county. The population of Conyers, the county seat, was 2,900 in 1960.
Previous Work
Watson (1902, p. 153-161) included a description of bis Lithonia contorted gra11ite-gneiss (termed Lithonia Gneiss in this paper) in Rockdale County in his report on the granites and gneisses of Georgia. The report was concexned primarily with the economic aspects of the Lithonia. Later work by Lester (1938) was done on the geology around Stone Mountain in nearby DeKalb County, Georgia. Criclanay (1952) reported on the general geology of the crystalline rocks of Georgia.
A repo1t by Herrick and LeGrand (1949) on the geology and ground-water resources of the Atlanta area included a brief discussion of the geology of Rockdale County and reported on the occurrence of ground-water and municipal-water supplies in the county.
Herrmann (1954) mapped a portion of Rockdale County in his work on the "Stone MountainLithonia district" of Georgia. His report included a geologic map, rock description tructure interpretati011 , and a discussion of the stone indus-

2

try in the area. Much of Herrmann's work has cover roo t of the northern part of the county.

been used in this report.

Other major rock units in decreasing order of

Acknowledgments

areal extent are garnet mica schist, muscovite quartzite, amphibolite gneiss, porphyroblastic bio-

The write1 is indebted to Mr. W. T. Green and the staff of t he Rockdale County Public Health Department for furnishing valuable assistance.

tite gneiss, and the Panola Granite of Herrmann
(1954). Minor rock units include diabase dikes, a pegmatite, amphibolite, and alluvium.

Thanks are also due the many people of Rockdale County who graciously offered information which
helped to make t his report possible. Suggest ions and helpful criticism by Mr . R. T. Bentley, formerly of the Georgia Department of Mines, Mining and Geology, are appreciated.

A mantle of decomposed residual rock called saprolite covers most of Rockdale County. Compo ition of the saprolite depends on the nature of the original rock and much of the geologic map-
ping was done on the basis of saprolite character. Exposures of fresh rock were found mostly in

The writer wishes also to aclmowledge the help of Mr. W. A. Martin of Virginia Supply and Well
Co. and Mr. Weisner of Weisner Well Drilling Co., who furnished well data.

road cuts and small stream valleys. Where the Lithonia Gneiss of Watson and t he Panola Granite of Herrmann occur, however, flat or gently sloping areas devoid of saprolite are exposed. Herrmann

Well-Numbering System

(1954, p. 3) calls this type of exposure "pavement." Locations of major "pavement" areas are

The well-numbering system used in t his report shown on tl1e geologic map {plate 1).

is based on the 72-minute quadrangle series of

the U. S. Geological Survey. Each 7lf2-minute

Lithonia Gneiss of Watson (1902)

quadrangle in t he State has been given a numbe1 and letter designation dependent on its location within the State. The numbers begin in the south-

Rock Description The dominant rock type in the northern part of

-

west corner of the State and increase numerically Rockdale County is a highly contorted gneiss.

eastward, and the letters begin in the same south- Herrmann (1954) classified this gneiss as a mig-

west corner and increase alphabetically northward, matite and called it "Lithonia Gneiss." Earlier

using the principle "read right up."

workers called it "granite gneiss, Lithonia type"

(Crickmay, 1952) and "Lithonia contorted granite

Parts of eight quadlangles compose Rockdale gneiss" (Watson, 1902). This report will follow

County. These quadrangles range in letter and Herrmann's revision and the term Lithonia Gneiss

number designation from 12CC to 14EE. In each of Watson will be used.

quadrangle wells are numbered consecutively as

they are scheduled. For example, the 13th well

The Lithonia Gneiss is typically contorted in

scheduled in quadrangle 14DD is numbered appearance. Layer of biotite alternating with

14DD13. A spring is numbered the same way ex- layer of quartz and feldspar accentuate the con-

cept that an "S" is inserted before the final num- torted appearance and impart a light-gray color

ber, such as in 14DDS1.

to the rock. The major portion of the rock is com-

posed of quartz and oligoclase with minor amounts

GEOLOGY

of biotite. The biot ite is lineated, giving a gneissic appearance. Herrmann (1954) reported garneti-

The State of Georgia is divided into four major ferous layers in the Lithonia Gneiss and a heavy

physiographic provinces on the basis of topogra- mineral residue of zircon, magnetite, and ilmenite

phy-Coastal Plain, Blue Ridge, Piedmont, and obtained from panning saprolite in a streambed.

Valley and Ridge. Rockdale County lies in the Piedmont Province whiCh is underlain by the old-
est rocks in the State. The rocks, for the most part, are sediments that were deeply buried in the past and subjected to high temperatures and pressures, which subsequently al tered the mineral
assemblages and folded the rocks into complex tructures. Later intrusions by igneous masses further deformed and altered the rocks.

Many dikes composed of aplite and pegmatite cut the Lithonia Gneiss of Watson, and a few are concordant with lineation. The pegmatites are
composed chiefly of quartz and oligoclase with accessory biotite and tourmaline. Injection of the aplite and pegmatite into the Lithonia is the basis
for its classification as a migmatite (Herrmann,
1954).

The geology of Rockdale County is shown as two major rock types on the "Geologic Map of Georgia" (Crlckmay, 1939). The unit shown in
the northern part of t he county is called granite gneiss, Lithonia type, of igneous origin, and the

Weathering of Watson's Lithonia Gneiss produces a saprolite that ranges in color from light
gray to light brown and is composed of sandy clay to clayey sand. In areas of higher biotite concen-
trations the saprolite is reddish brown.

unit shown iu the southern part of the county is referred to as biotite gneiss and schist, Carolina Series, of metamorphic origin. Both units ru:e thought to be of Precambrian age.

Exposures of Lithonia Gneiss frequently occur as areas of "pavement" from a fraction of an acre to several ac1es in extent. The pavement or bare rock generally follows the usual land-.surface con-

The geologic map of Rockdale County (plate 1) toms with spalling occurring parallel to the sm-

shows the six major rock units and several minor face contours rather than along lineation planes.

rock units. The most predominant rock unit is Because this rock is exposed so frequently and

the Lithonia Gneiss of Watson (1902), which because it bas properties suitable for dimension

3

stone, it has been utilized extensively as building stone and crushed rock. Evidence of numerou small abandoned quarries was found in Rockdale County, though at present there are few operating ompanies t hat quarry Lithonia Gneiss. Large quarries are operating ju t east of the area in DeKalb County.
Water-Bearing Characteristics
Because the Lithonia Gneiss of Watson (1902) underlie so much of Rockdale County it is very important a an aqujfel'. Records of wells in the gneis- indicate that dug wells are the most abundant sources of water supply, drilled wells are econd in number, a11d bored wells are the least utilized. The average depth of dug wells is about 35 feet on hilltops and hillsides and about 16 feet in valleys. Drilled wells on hilltops have an average depth of 295 feet and about 37 feet of casing; those on hillsides average 249 feet and nave 40 feet of casing, and drilled wells in the valley average 300 feet in depth and have 46 feet of casing. Bored wells average about 45 feet on hillsides and hilltops. No records of bored wells in valleys were reported.
The yield of dug and bored wells was not teported. Rec01ds of (hilled wells show an average yield of 26 gpm (gallons per minute) for hilltop wells, 73 gpm for hillside wells, and 47 gpm for valley wells. Two drilled wells, a dug well, and a bored well on hilltops were reported to be inadequate an<l one well drilled in a small valley was reported to have been dry.
The reported quality of water f1om wells penettating Lithonia Gneiss is good. No watet of poor quality i recorded from drilled or bored wells. Water from a few dug wells, however, was re~ ported to have a limy taste o1 as being milky. 'l'he limy taste and milky color probably are derived from suspended kaolin in uncased dug wells, a weathering product of feldspar minerals in the gneiss. Objectionable amounts of iron were re~ ported in a few dug wells. Large amounts of biotite could cause objectionable iron. Corrosion of pipes in the water system by acidic water could also cause objectionable iron.
Garnet Mica Schist Rock Description
Structurally overlying t he Lithonia Gneiss of Watson (1902) is a group of rocks which include muscovite-biotite garnet schist, biotite gneiss, and amphibolite gneiss. Interlayered with these rocks is a highly resistant, ridge-forming muscovite quartzite, which will be discussed separately. These rocks were mapped as "Brevard Scltist" on the geologic map of Georgia. This report, how.ever, will follow Herrmann (1954), who gave them .a purely lithologic group name of garnet mica .schist because, he reported, they do not fit the original de11cription of the Brevard Schist as given by Keith (1907).
The garnet mica schist crops out in isolated areas surrounded by Watson's Lithonia Gneiss in the northwestern part of the area and in the west-

central part of Rockdale County it occurs adjacent to the Lithonia Gneiss.
Very few exposures of fresh muscovite-biotite ga1net schist were found. It is darl< gray il1 color, where fresh, and composed of garnetiferous muscovite-biotite layer with as ociated qnaltz-feldspar bands. The weathered rock is brownish red to red and the completely weathered saproHte is a micaceous red clay. Similarly, the biotite gneiss and amphibolite gneiss were found mostly a saprolitic material. The biotite gneiss i medium to fine grained with a banding of biotite in a matrix of quartz and feldspar. It weathers to a brownish-red, lightly sandy clay. Discontinuous amphibolite gneiss layers weather to dark-1eddish~ bl'own clay. Numerous pegmatites cut the garnet mica schist. Many of the pegmatites contain welldeveloped tourmaline crystals.
Water-Bearing Characteristics
Records of wells in garnet mica schist are few. Of the drilled wells repo ted, the average depth on hilltops is 137 feet and length of casing 24 feet; on hillsides the average depth is 175 feet and the casing 23 feet. No drilled wells in valleys were reported. Dug well average 39 feet on hilltops and 28 feet on hillsides and in valleys. There are no records of bored wells .
The average yield of wells drilled on hilltops is reported to be 60 gpm and the yield of hillside wells, 12 gpm. The quality of water f1om the drilled wells, except from well 13DD7, is reported to be good. (See table 2.) Dug wells yield water reported to be only fair to good . E.."<cess iron is t he most objectionable constituent of water from garnet mica schist.
Muscovite Quartzite Rock Description
A distinctive layer of ridge-forming muscovite quartzite crops out in the northwestern part of Rockdale County along the Rockdale-DeKalb County line. The tock unit can be traced eastward into DeKalb County and then southward until it reenters Rockdale County in the west-central part. Although t he muscovite quartzite is a thin unit (50 t o 100 feet) compared with the other major rock units, it is mapped separately becau e of its persistent tidge-forming character. The muscovite quart21ite is interlayered with garnet mica schist, and Herrmann (1954) groups them together as a f ormation.
The quartzite, when fresh, is light gray to brownish gray and very hard. It is composed mostly of quartz with disseminated flakes of muscovite. Saprolite formed from weathering of the quartzite is a brownish-gray clayey sand.
Water-Bearing Characteristics
Only one well in muscovite quartzite has been reported. Because of its ridge-forming occurrence,
few homes are located where it crops out. It is a.
highly fractured rock and therefore a potentially excellent aquifer. Bored and dug wells would be

4

difficult to construct because there is little saprolite cover on the quartzite.
Porphyroblastic Biotite Gneiss Rock Description
The southeastern part of Rockdale County is underlain by a group of rocks designated as porphyroblastic biotite gneiss. Included in this group of rocks is porphyroblast ic biotite gneiss interlayered with thin nonmappable units of fine-grained biotite gneiss, sillimanit e-quartz schist, muscovitebiotite schist (sometimes garnetiferous) , phlogopite quartzite, and amphibolite gneiss.
The medium- to coarse-grained porphyroblastic biotite gneiss is coarsely layered. Biotite layers alternate with quartz-plagioclase layers. The latter contain andesine porphyroblasts. Fine-grained biotite gneiss is interlayered with the porphyroblastic biotite gneiss. It is composed of quartz and plagioclase with accessory lineated biotite. The partially weathered biotite gneisses are wellbanded soft sandy clays, and the completely weathered saprolite is brownish-red clay.
Quartz veins and pegmatite dikes are numerous in the porphyroblastic biotite gneiss. They are usually less than a foot thick, but some pegmatites may cover large areas.
Water-Bearing Characteristics
In the area underlain by porphyroblastic biotite gneiss wells drilled on hilltops average about 325 feet in depth with 63 feet of casing, wells drilled on hillsides average about 282 feet with 62 feet of casing, and drilled wells in valleys average about 193 feet with 47 feet of casing. Bored wells average about 30, 37, and 20 feet on hilltops, hillsides, and in valleys. The average depths of dug wells are approximately 42 feet on hilltops, 32 feet on hillsides, and 21 feet in valleys.
Yields of drilled wells are about the same for hilltop and hillside locations (17-18 gpm), and wells in valleys average only about 9 gpm. Inadequate supplies we e reported from two wells drilled on hillsides and one well drilled in a valley.
The reported quality of water from dug, bored, and drilled wells was mostly good. About 78 pe1 cent of the well owners who were interviewed reported good water, 12 per cent reported fair water, and 10 per cent reported poor water. The most objectionable constituent reported was excessive iron. The variance in quality is probably because of the large number of different, nonmappable, rock units. The poor-quality water is probably ass ciatecl with the amphibolite gneisses, which contain many iron-bearing minerals.

part of the county adjacent to the Panola Granite of Herrmann (1954), another unit crops out in the east-central part of the county, and a third occurs in the northeastern part of the area.
The amphibolite gneisses are composed mostly of hornblende with some epidote and biotite alternating with plagioclase-rich layers. Biotite gneiss and biotite schist are interlayered with the amphibolite gneisses and pegmatite dikes are common. Layering of the amphibolites is irregular.
The amphibolite weathers to an ocherous yellowish-brown to reddish-brown soft rock and finally to a dark-red clay. The saprolite is distinctive because of the dark-red color.
Water-Bearing Characteristics
Information on wells penetrating amphibolite gneiss is sparse. Well construction should be similar to that of porphyroblastic biotite gneiss. QuaUty of water from wells on record is fair. It is expected that excessive iron would occur in water from amphibolite gneiss because of the high iron content of the mineral constituents.
Panola Granite of Herrmann (1954)
Rock Description
The Panola Granite of Herrmann (1954) crops out in the southwestern part of Rockdale County forming a dome-shaped mass intruded into porphyroblastic biotite gneiss which projects about 200 feet above the surrounding countryside. This mass of granite is called Pig Mountain on the U. S. Geological Survey topographic quadrangle map of the area.
The texture of the granite is porphyritic. Large phenocrysts of microcline occu1 in a groundmass of quartz, oligoclase, and biotite. Inclusions of biotite gneiss from several inches to several feet across are found in the Panola Granite in a road cut adjacent to Georgia Highway 155 southwest of Pig Mountain. Thin pegmatite dikes composed of quartz and feldspar with radial clusters of tourmaline also were found at this location.
The Panola Granite weathers to light-gray to brownish-red sandy saprolite. It is the only rock unit other than the Lithonia Gneiss that forms pavement.
Water-Bearing Characteristics
Little is known about the water-yielding characteristics of Herrmann's Panola Granite. The average depth of the three d1illed wells on record is 410 feet, and the average casing depth is only 10 feet. The quality of the water is reported to be fair.

Amphibolite Gneiss Rock Description

Pegmatite Rock Description

In addition to the amphibolite gneisses that are commonly interlayered with porphyroblastic biotite gneiss and garnet mica schist, three large masses of amphibolite gneiss occur in Rockdale County. One mass crops out in the southwestern

All rock units in the a1ea are intruded by numerous pegmatitic dikes, but only one pegmatite was found to be of mappable size. This pegmatite is in the southern part of the county and intruded into porphyroblastic biotite gneiss. Although no

5

actual outcrop was found, float in the form of large feldspar crystals, quartz, and muscovite books covered an area about 150 yards in diameter. Location of this pegmatite is shown on the geologic map (plate 1).
Water-Bearing Characteristics
No known wells have been drilled in pegmatites in Rockdale County. The only pegmatite of mappable size would probably yield water of good quality, because the physical characteristic of pegmatites make them susceptible to fracturing, thus facilitating the circulatiou of meteoric wate1s.
Diabase Dikes
Rock Description
Numerous diabase dikes occur in the northern part of Rockdale County. They range in thickness from less than a foot to more than 30 feet. Several dikes appear to be continuous across the entire county, striking N. 30 W. to N. 45 W., and smaller dikes are evidently discontinuous. Herrmann (1954) reported dikes in the Stone Mountain-Lithonia area strildng in the same general direction. The dikes in Rockdale County are probably a continuation of the dikes reported by him.
The dikes are composed of black diabase. According to Lester and Allen (1950) the component minerals in the diabase are plagioclase and pyroxene and smaller amounts of olivine, hornblende, magnetite, and PYl'ite. The dikes are highly fractmed and weathering takes place in a circular pattern ftom the fractures inward. Weathering of the dikes forms a soft yellowish-brown ocherous

clay. A small nodular mass of the rock is often c.ompletely weathered on the outside and fresh 011 the inside.
Water-Bearing Characteristics
Although diabase dikes are very thin, they are potentially excellent aquifers. Their highly :fractmed 11ature makes them good water conduits and when intersected below land surface they should yield large quantities of water. Well 14DD2 is drilled adjacent to a dike which dips toward the well. A yield of more than 100 gpm wa. reported by the driller. The quality of the water from this well is shown on table 2.
Alluvium Rock Description
Alluvium, a13 shown on the geologic map, consists of stream-deposited sand aud gravel and is restricted to the :flood plains of the major rivers and larger creeks. Although some of the smaller creeks may have alluvial deposits in small flood plains, they are not mappable at the scale of the geologic map (plate 1).
Water-Bearing Characteristics
Alluvium in Rockdale County is rarely utilized as an aquifer because of its location in low areas subject to periodic flooding. It is potentially produ.ctive by means of dug wells where its thickness is great enough.
GROUND WATER
In those areas of Rockdale County where treated surface water is not available, ground water is

Nonlayered rocks IF,cto"d ood joioted) ~

STREAM SPRING
DUG WELL

~
Figure 2.-0ccurrence of g1ound watm in nonlaye1ed 1ocks.
6

utilized for human consumption, for watering of stock, and for some irrigation. Ground water is water beneath the land surface in the zone of saturation, or water that occupies pore spaces in the saprolite, and in cracks, crevices, and openings in the underlying rock.
Occurrence
Rainfall, percolating downward, b e c o me s ground water when it reaches the zone of saturation. Not all rainfall, however, becomes ground water; evaporation, transpiration, and runoff claim a large portion. Once the water reaches the zone of saturation, it is stored in the pore spaces of the saprolite and in the cracks and crevices of the rock beneath the saprolite.
The top of the zone of saturation is called the water table. In a well that penetrates the zone of saturation the level of water in the well coincides with the water table. Generally, the water table reflects the topography, but on hilltops it is farther below the land surface than in the valleys. Where lakes and streams occur the water table intersects the land surface at their surface level.
Fluctuation of the water table is related to precipitation. Usually there is a lag from the time precipitation occurs until the water reaches the water table and the water level in a well rises. Similarly, a low water table lags dry spells. In late fall and early winter the water table is usually
at its lowest point. It begins to rise in late winter and reaches its peal< by late spring.
Ground-water occurrence in nonlayered rocks is illustrated on figure 2. In Rockdale County

nonlayered rocks include the Lithonia Gneiss of Watson (1902) and the Panola Granite of Herrmann (1954). Becau e interstitial openings are small, ground-water storage and movement is limited to fractures. Fractures in the rock are the result of exfoliation, structural disturbances, and weathering. Exfoliation in homogeneous rock masses occurs roughly parallel to the surface of the rock mass, and the e>.."foliation fractures are usually more pronounced on the slopes and in the valleys surrounding the rock masses. Joints are caused by structural deformation and are important water conduits. Weathering enlarge. exfoliation fractures and joints.
Fi~ure 3 illustrates the occurrence of ground water in layered rocks. Porpbyroblastic biotite gneiss, garnet mica schist, amphibolite gneiss, and muscovite quartzite are the important waterbearing units that consist of layered rocks in Rockdale County. In these rocks ground-water movement is controlled largely by fracturing parallel to the layering. Highly fractured layer often alternate with more competent laye1s and gl'onnd-water movement may be restricted.
Discharge and Recharge
Dischru:ge of ground water takes place by either natural or artificial processes. Natural discharge of ground water is the proces whereby water is removed from storage and returned to the atmosphere by natural means. It occLu- when ground water discharge into spring , streams, and lakes and when it is transpired by vegetation. Discharge of ground water by artificial proces es takes place when water i removed from the zone of aturation by means of wells.

Water-bear ing rock Non-water-bear ing rock
STREAM SPRING

Figure 3.-0ccwrence of ground water in layered rocks.
7

Recharge of water to the zone of saturation is mainly by downward percolation of rainfall. Recharge may take place also when the water table in the vicinity of lakes and streams is low. Water from the lakes and streams then tends to flow toward the areas of water-table depression. The rate of 1echarge depends on the permeability of the unsaturated material.
Well Construction
Three types of wells are utilized in Rockdale County-dug, bored, and drilled. Dug and bored wells obtain water mostly from the saprolitic material in the subsurface. Drilled wells penetrate the underlyh1g 1ock and obtain water from openings, cracks, and crevices in the rock. Figure 4 illustrates the three types of wells.

BORED WELL 30"

DUG WELL 36"

DRILLED WELL 6"

the rock beneath the saprolite. The diameter of drilled wells averages 6 inches. Pumps are used to remove water from them.
Yields of Wells
Drilled wells are usually the most reliable of the three types of wells because they obtain water from g1eater depths than dug or bored wells and, therefore, a1e not so susceptible to water-table fluctuations. Crystalline rocks have been compacted and recrystallized by deep burial and the interstitial openings are minute and afford little room for water storage. Therefore, to be productive a drilled well must intersect f1actures in the rocks that are interconnected with either the surface or the saprolite. Records show that wells drilled through a thick saprolite cover are usually more productive than wells drilled through a thin saprolite cover, or wells that have no saprolite cover. The saprolite acts as a sponge, retaining the water until it is needed and then permitting it to move through the rock fractures into the well bore.
Two major factors affecting the yield of dug and bored wells are saprolite permeability and depth of penetration into the saturated zone. Permeability of the saprolite determines the rate of ground-water movement through it, and thickness of the saturated zone penetlated determines the amount of water stored in the well bore. Because saprolite permeabilit-y is usually low, withdrawals in excess of the amount the saprolite will yield to the well bore must come from the water stored in the well. If the well has penetrated only a few feet of the saturated zone and the withdrawal is greater than the amount of water flowing into the well, the well will be pumped dry in a short time. It is important, therefore, to construct the well so that there is ample storage of water in the well bore to meet the peak demands.

Figure 4.-Construction of bored, dug, and drilled wells.
Dug wells are usually prepared with a pick and shovel. Consequently, they are the shallowest type of well and are generally confined to the saprolite. When cased, concrete pipe is most often used, but a dug well may be shored with wood or may be bricked. Often only the bottom portion of the well is cased; usually that portion of the well below the water table. The water in a dug well is generally drawn by hand, but many wells are equipped with shallow-well pumps.
Bored wells are confined entirely to the saprolite, because a well-boring machine is not capable of penetrating hard rock. In areas where the water table is near the base of the saprolite bored wells cannot be used. Concrete pipe, 24 to 36 inches in diameter, is used to case bored wells from the land surface to the bottom of the well. Water enters the well through loose-fitting joints in the pipe and through the bottom of the well. Pumps are almost always installed in bored wells.
Drilled-well construction differs greatly from that of bored and dug wells. The saprolite is cased out with steel pipe and an open hole is drilled into

SURFACE WATER
Surface water is furnished to the cities of Conyers and Milstead by the Conyers Water Treatment Plant. In addition to furnishing water to residents of these towns, heated surface water is supplied also to several industries in the immediate vicinity of Conyers.
The Conyers Water Treatment Plant is located about three-fourths of a mile northeast of the Conyers city limits on Georgia Highway 20. Yellow River water is supplied to the plant by a pumping station about half a mile north of the plant, where Highway 20 crosses the river. A flocculating agent is added, after which it is sand filtered. The pH of the water is adjusted with lime, chlorine and fluoride are added, and the water is distributed. Analyses 13 and 14 in table 2 show the chemical quality of raw water and treated water from the Conyers Water Treatment
Plant. The capacity of the treatment plant is 1%
mgd (million gallons per day).
WATER QUALITY
The chemical quality of ground water in Rockdale County is governed by the type of rock

8

in which the water occurs. Rain, relatively free of chemical impurities when falling, dissolves chemicals out of the saprolite and rock as it percolates downward. Some chemical constituents are harmful when taken internally and others are not desirable because of a displeasing taste or smell. Most industrial users require water low in dissolved chemical constituents and spend a great deal of money treating water to make it suitable for use.
The U. S. Public Health Service (1962) has recommended limits of chemical concentrations for drinking water used by carriers subject to Federal Quarantine Regulations. These minimum standards should be adhered to by all persons consuming water. A few of the more important concentration limits for chemical constituents are listed in table 1.

] "
0...-40\0\"''i-t-"d'NI"'lOOOOOO r--:\d'Ci~\0~\0~\Ci~~~\Ci
0
"'
(runs) spnos !:::; pouqosSJQ -

Table !.-Recommended mtmmum standards of water quality (based on U. S. Public Health Service drinking water standards, 1962).

Chemical constituent

Recommended limit (parts per million)

Iron (Fe) Magnesium (Mg)
Sulfate (S04) Chloride (C1) *Fluoride (F) Nitrate (N03) Dissolved solids

0.3 125
250 250
1.2 45
500

Table 2 lists chemical analyses of water from wells, a spring, and treated and untreated surface water from the Conyers Water Treatment Plant. Analyses of water from the six major rock groups in Rockdale County show that only one chemical constituent found in the water exceeds the U. S. Public Health Service standards. That constituent is iron and in only two samples is the amount of iron excessive. An analysis of water from garnet mica schist exceeds the recommended limit of 0.3 ppm (parts per million) by about 13 times. The other analysis of water from porphyroblastic biotite gneiss shows just slightly more than the recommended limit.

Iron in excess of 0.3 ppm tends to stain clothes and imparts a bitter taste to the water. Magnesium, in combination with the sulfate ion, has a laxative effect and causes scaling in boilers. Concentrations of sulfate and chloride in excess of 250 ppm are objectionable primarily because of bad taste. The same is true for total dissolved solids in excess of 500 ppm.

Excess nitrate in the water can cause death in infants (methemoglobinemia) during their first few months of life, and both humans and animals can be poisoned by nitrate if the concentration is great enough. Few nitrate minerals occur in Rockdale County and nitrate concentrations shown in table 2 are we11 below the recommended limit of 45 ppm set by the U. S. Public Health Service. However, the major cause of pollution by nitrate

Recommended limit for the average maximum temperature in Rockdale County.
9

(.,J:) ~ ~ "! ~ c: "! <'! ": ~ c: "! "! I

c:

apJ.IOnJ.!I o

-

( 1::>)
app:o[q:J

q -

"'l q
Ln

q

~ "r-i' "vi' rf"J "rri' ".,...'; l.l"l C"'l

~

<o::>> o o o o o o o o o o o o o

0

a~vuoq~"::>

(CQ:>H) ate \0 1.0 oo N oo oo N ...-4 N ll"l 1.0 V N -uoq.aeoJo: r- """ N ..::t 0\ N t"l M - -.:t N N

"'"'"' ()I) "'!
WnJSSl!~Od ~

~N.,...;

~~

~~
~~

"' '0'0~ :::: -a. .... .... "'"'

("N) wn!pos

~

rriviN

~rri

.,OV>

"o'<'> (8W)
wnJsau.aew

.... ~r-:...".."'1

\l'!o...,.V'IN.. ~ ~ N N

( 9 .:1) o "~ o ~ o ~ 1- ~ N o V) uo.q 0 ....;

0
"'

is from use of nitrate fertilizers and from human and animal wastes. Any well located near a fertilized field, septic tank, or parnyard is susceptible to nitrate contamination, especially if improper construction permits surface water to flow into the well.

In "Drinking Water Standards" published by
the U.S. Public Health Service (1962) it is stated that "Fluoride in drinking water will prevent dental caries" and that ". . . no ill effects will result when the concentration is optimum." The fluoride concentration in water for human consumption is based on the annual average of maxi-
mum daily air temperatures. The recommended
concentrations are lower for those areas having higher annual average maximum daily air temperatures. The recommended range of concentra-
tion is from 0.7 to 1.2 ppm, and the optimum concentration is 0.9 ppm for an annual average maximum daily air temperature that ranges from 63.9 to 70.6 F. Rockdale County's average maximum daily air temperature is within this range. As can be seen from table 2, ground water in
Rockdale County contains little fluoride, the highest concentration shown being only 0.4 ppm. Sul'face water users, however, have the benefit
of fluoridated water.

Most ground water in Rockdale County is acidic. Such water is corrosive and when in contact with rocks containing iron it tends to dissolve iron from them. Raising the pH of the water decreases its corrosiveness and precipitates the iron. A simple way of raising the pH is to run the water through marble chips. Reaction of the basic chemicals in the marble with the acidic chemicals in the water has a neutralizing effect. Because the iron in solution is not stable in neutral or basic water, it will precipitate and form a coating on
the marble chips. Periodic cleaning of the marble chips renews their effectiveness.

Marble chips can be placed directly in bored

and dug wells because of their large diameter.

Because drilled wells have such a small diameter

and the pump is often placed near the bottom of

tahetawnkell~ri

t is necessary to run reservoir containing

the water through the marble chips.

Dr. S. M. Herrick of the U. S. Geological Survey

suggested (oral communication, Feb. 23, 1965)

that wooden baskets be made to hold the marble

chips and that the basket be lowered in the dug

or bored well. Periodically the basket could be

raised and the marble chips cleaned.

water is only 25 gpd and that the rural population is approximately 9,000 (based on 14,000 t~tal population), the total ground-water consumption in Rockdale County is about 225,000 gpd.
Surface-water use in Conyers and Milstead, including industrial use, averaged about 551,000 gpd during 1964 (Warren Griffin, personal communication, Feb. 11, 1965). This added to the 225 000 gpd of ground water consumed by rural residents gives a total of approximately 776,000 gallons of water used daily during 1964 in Rockdale County.
CONCLUSIONS
Ground water is not present everywhere in Rockdale County in the amounts needed for modern day living. It is important, therefore, when drilling a well to pick the best location available. Well records show that geology and topography play an important part in whether or not a well is successful. The location of a well with respect to fracture patterns in homogeneous rock or with respect to recharge of water-bearing layers in layered rock determines the well yield. When rock exposures are not available topographic features and saprolite thickness criteria must be used to determine the best well location.
Chemical quality of ground water in Rockdale County is generally good. Most water is soft and has a low dissolved-solids content. In isolated areas throughout the county excessive iron has been reported.
RECORD OF SPRINGS AND WELLS
The locations of the springs and wells in the following tables are shown on plate 1.
SELECTED REFERENCES
Crickmay, W. S., 1952, Geology of the crystalline rocks of Georgia: Georgia Geol. Survey Bull. 58, 52 p.
Crickmay, W. S., and others, 1939, Geologic map of Georgia: Georgia Geol. Survey Map.
Herrick, S. M., and LeGrand, H. E., 1949, Geology ~nd ground-water resources of the Atlanta area, Georgia: Georgia Geol. Survey Bull. 55, 121 p.
Herrmann, L. A., 1954, Geology of the Stone MountainLithonia district, Georgia: Georgia Geol. Survey Bull. 61, 193 p.
KeithU.ASr.thGuerdl.19S0u7r,vDeyesGcreioplt.ioAntloafs,thFeoPliiosg1a4h7.quadrangle:

WATER CONSUMPTION

Lester, J. G., 1938, The geology of the ':'egion around ~tone Mountain, Georgia: Colorado Umv., Ph.D. Thesis.

An estimate of the total water consumption per day in Rockdale County can be made by figuring the per capita ground-water consumption and adding it to the total surface-water consumption. The national average per capita consumption is approximately 50 gpd (gallons per day). Th~s figure is probably high for the average rural resident of Rockdale County because of the large number of dug wells without pumps in use. Assuming that the per capita consumption of ground

Lester, J. G., and Allen, A. T., 1950, Diabase of the Georgia Piedmont: Geol. Soc. America Bull., v. 6, p. 12171224.
Sever, C. W., 1964, Geology and ground-water ~esources ?f crystalline rocks, Dawson County, Georgia: Georgia Geol. Survey In. Circ. 30, 32 p.
Watson, J. L., 1902, A pre}iminary r~port on the granites and gneisses of Georgia: Georgia Geol. Survey Bull. 9-A, 367 p.
U. S. Public Health Service, 1962, Drinking water standards: Public Health Service Pub. 956.

10

Table 3.-Record of springs in Rockdale County.

Spring No.

Owner

Location

Type of
rock

Yield (gpm)

Use Dependability

Remarks

13CCS1 Evan Farmer

Draw

Garnet mica

4-5 None

schist & gneiss

Good

S2 Lowland Mitchell

do

Garnet mica schist

Domestic

do

S3 Monastery of the Holy Ghost

Hillside

12

do

do

S4 J. R. Young

Foot of hill

2

do

do

13DDS1 Morris Jackson

Small valley

Lithonia Gneiss

4

do

do

S2 G. Van Greene, Jr. Sloping hilltop

do

Domestic & do stock

S3 J. F. Camp

Small draw

2 None

do

S4 B. Frank Nash

do

4

do

do

S5 T. A. Wajcik

Foot of hill

Domestic & do No overflow. stock

S6 Ernest Bradford

do

3 None

do

14CCS1 Charles Hunter

Low depression

30 Domestic & do stock

14DDS1 Parks Printing Co. Small valley

Lithonia Gneiss

10 None

do

S2 W. D. Merritt

Sloping hillside

20 Domestic

do

S3 C. R. Hayes

Edge of small Saprolite valley

10

do

do

S4 H. T. Humphries

Sloping hillside

10

do

do High iron content.

S5 W. E. Singleton

Depression in hillside

Garnet mica schist

Stock

do

S6

do

Depression near do hilltop

do

Fair Dry in ex-

tremely dry

weather.

S7 G. P. Owen

Foot of hill

1 Domestic Good

S8 E. A. Braswell

Draw

5

do

do

S9 Mrs. Grace McGettie Draw at foot of hill

2

do

do

SlO John H. Morris

do

2

do

do

11

Well No.

12CC1 2 3 4 5 6
12DD1 2
13CC1 2 3 4

.......
I):)

5

6

7

8

9

10

11

12

13

14

15

16

17 18 19 20 21

Owner
H. B. Toney Mr. Mitchell W. T. Ward W. F. Hammonds Jerry Taylor James F. Berry F. E. Alexander
do Joe Katz M.W.Hill C. H. Phelps H. G. Conner
John C. McGehee W. A. Staples W. G. Gleaton Evan Farmer Paul Staple Jack Parris H. M. Duke Charles Patrick Walker Smith
G. J. Hammonds W. L. Susong
Monastery of the Holy Ghost do do
J. R. McElhattan J. L . Moon A. B. Paul

Type of well
Drilled do do
Bored Dug
do Drilled Dug Drilled
do Dug
do

Table 4.-Record of wells in Rockdale County, Georgia.

Topography

Diameter of well (inches)

Depth (feet)

Cased to (feet)

Water-level
below land
surface (feet)

Date measured

Hillside do
Hilltop Flat Hilltop
do do Hillside do Flat Hillside do

6 353

6 340

6 143

24

36

32

30

30

6 145

36

50

6 608

6 134

36

19

30

38

10 10 5
30 50 None 55 82 None None

45

Reported

28

Reported

25

do

50

do

40

Reported

35

do

8.6 May- 1964

11.5 May- 1964

do do do do do do do do Drilled Bored Dug Drilled

do Ridge Hillside
do Hilltop Hillside
do Flat Hillside Hilltop
do Hillside

30

25

36

37

36

20

36

33

36

50

36

29.5

36

28

36

30

6 100

30

51

36

20

6 246

25 None None None None None None None 63 51 None

19.5 Sept- 1964

15.0

Reported

38

Reported

26.5 Oct - 1964

22.0

Reported

21.8

Oct - 1964

30

Reported

49

do

18.0 Nov- 1964

do

do

do

do

do

do

do

Hilltop

do

do

8 307

26

8 621

57.5

6 250

6 380

6 214

15.0

Reported

77.5

do

36.4 Jan - 1965

Yield

(g pm)

Use

Remarks

22+ Domestic

do

10

do

do

do

do

45

Domestic & stock High iron content.

Domestic

10.3 Domestic & stock

6

Domestic

do

do

Can be pumped

dry.

do

do

do

do

High iron content.

do

do

do

Domestic & stock Do.

20

Domestic

Do.

Domestic & stock

do

Do.

22

None at present

9.9

Domestic & stock

4

None

Domestic & stock

Domestic

Do.

40

do

Well No.

Owner

Type
of well

13CC22 23 24

A. B. Paul do do

Dug Drilled Dug

25

do

do

26

do

do

27

J. F. Thomson

Drilled

28

Kirkus Contr. Co.

Bored

29 John H. Anderson, Sr. Drilled

30

Robert Kirkus

Dug

31

Irvin Smith

do

32

R. W. Hammons

do

33

Sam Walden

do

......

~

34

I. W. Smith, Sr.

do

35

Essie Davis

do

36

Joseph Davis

do

37 38 39 40 41 42 43 44 45 46 47 48
13DD 1

Marion Hill Junior Kind Clark Harrison Walter Green B. A. Hasty
do do Mr. C. L. Blackmon H. K. Wood J. R. Young Plantation Manor Presbyterian Home Mission Joe Underwood

do do do do Drilled do Dug do do Bored Drilled do
do

Table 4.-Record of wells in Rockdale County, Georgia (continued).

Topography

Diameter
of well Depth (inches) (feet)

Cased to (feet)

Water-level below land
surface (feet)

Date measured

Yield (gpm)

Hilltop Hillside

36

38

None

26.1

Jan - 1965

6

250 ?

do

36

24

14.5

Jan - 1965

Hilltop do
Hillside do

36

61

36

43.4

6

187

30

30

None

39.5

Jan - 1965

None

37.1

Jan - 1965

64

45

Reported

18

30

10

do

do

6

do

36

Draw

30

Hillside

40

do

40

Ridge

30

Hillside

36

Creek

30

bottom

Hilltop

30

Ridge

30

Hillside

36

do

36

Hilltop

6

do

6

Hillside

30

do

36

Hilltop

36

Hillside

30

Slope

6

do

6

227 42 10.4 42 35 41.0 29 19.5
44.5 30 40 40 165 202 55 25.5 40 20 235 340

61 42 10.4 None None None None 19.5
None None None None

24

Reported

9.3

Feb - 1965

38

Reported

23

do

36

Feb - 1965

10

Feb - 1965

15.7

Feb - 1965

33.9

Feb - 1965

24.1

Feb - 1965

32.3

Feb - 1965

25

Feb - 1965

42

40

Reported

23

25

45

do

None

17.3

Feb - 1965

None

28

Reported

20

17

do

25

do

50

20

Hilltop

6

396

34

1-2

Use

Remarks

Domestic

do

do

Water quality

poor.

do

do

Domestic & stock

Domestic

Water tastes of lime.

do

Domestic & stock

do

do

do

do

Domestic

Some iron content.

do

do

do

do

Domestic & stock

do

do

do

Domestic

do

do

Inadequate supply.

do

do

do

Well No.
13DD 2 13DD 3
4 5 6 7 8 9 10 11 12 13 14
1-' ~
15 16 17 18 19 20 21 22 23
24 25 26 27 28 29

Owner
Abbot Estates do
J. E. Abbot Ed Turner Martin Hurst
do Mercer Rowan J. J. Mitchell, Jr. Charlie Wilson Phillips 66 Station W. W. Parker Mrs. E. H. Plunkett William A. Hinton
G. Van Green, Jr. do
Joe H. Bennett Camp Westminster
do do H. M. Pace W. L. Gainer Green Meadows Memorial Garden R. H. Johnson Frank Fagan B. R. Miller Frank Johnson J. F. Camp Jerald Ledford

Type of
well
Drilled do do
Dug Bored Drilled Dug Drilled Dug Drilled
do Dug
do
do do do Drilled do do do do do
Dug Bored Dug
do do Dug

Table 4.-Record of wells in Rockdale County, Georgia (continued).

Topography

Diameter
qf well Depth (inches) (feet)

Cased to (feet)

Water-level
below land
surface (feet)

Date measured

Yield (gpm)

Hillside

6

do

6

Hilltop

6

Hillside

36

do

30

do

6

do

36

do

8

do

35

Hilltop

6

Hillside

6

Flat land -

Hillside

54

250 135 137
30
-
-
27
372
-
239
538
-
25

18

10.0

Reported

50

21.5

38

do

20

8

11.0

do

34

-

-

-

-

-

-

27

-

-

-

-

-

-

-

-

-

28

15

Reported

200

-

-

73

-

-

-

-

-

-

-

-

-

-

16

-

-

-

-

-

-

do

-

25

Hilltop

-

30

Valley

-

23.6

Hilltop

6

209

Hillside

6

221

do

6

267

do

6

46

Hilltop

6

196

do

6

470

-

-

-

-

-

12.5

May -1964

-

-

10.2

May -1964

-

46.5

31.3

May -1964

35

43

0

Reported

13

30

45

34.5

-

-

-

do

3

-

25

-

%

61

30

Reported

1

Flat

30

Hilltop

30

do

-

do

36

do

36

Hillside

36

17.3

18

11.9

Sept-1964

-

36

None

31.8

Sept-1964

-

20

-

-

-

28.7

6

215

Feb -1965

-

23

23

10.7

Feb -1965

-

55

55

50

Reported

-

Use

Remarks

Public supply

do

Domestic

do

do

do

High iron content.

do

Do

do

Water seems hard.

do

Industrial

Domestic & stock Causes iron stain.

Domestic

do

Supply inadequate

in dry weather;

high iron content.

do

do

do

High iron content.

Public supply

do

do

Domestic

do

Supply inadequate.

Industrial

Do

Domestic None Domestic
do do Domestic & stock

Do Some sulfur content.

Well No

13DD30

31

32

33

34

35

36

37

38

39

40

41

42

.......

01

43

44

45

46 47 48 49 50

51 52 53 54 55 56
13EE 1 2

Owner
Roy M. Bond, Sr. Coy Elliott Lee Owens
J. H. Oglesby Mrs. Eula Bradford James E. Williams
Luther Blake Mrs. E. B. Burnham
Hiram Dunn Vaden White
do Tom Granade Charles Codney
R. P. Hull Lewis Hull J. C. Kilgore
Terrell Underwood Robert Cornwell Joseph Smith do Willis J. Johnson
J. W. Bruce Tom Parker J. A. Stanton City of Conyers
do do C. S. Farmer 0. R. Ellington

Type of
well
Dug do do do do do do
Drilled Dug
do do do do do Drilled do
Dug do do do do
do do Drilled do do do Dug do

Table 4.-Record of wells in Rockdale County, Georgia (continued).

Topography

Diameter
of well Depth (inches) (feet)

Caoed to (feet)

Water-level below land
surface (feet)

Date measured

Yield (gpm)

Hillside

36

44

None

48

Reported

do

30

37.4

37.4

31.3

Feb -1965

Hilltop

36

21

None

13

Feb -1965

Hillside

36

22.5

None

16.7

Feb -1965

Hilltop

36

32.5

None

27.0

Feb -1965

Valley

36

15

None

9

Reported

Hilltop

48

None

None

18.7

Feb -1965

Hillside

6

151

11

33

Reported

17

Hilltop

36

28

None

26.2

Feb -1965

do

48

26

None

21.2

Feb -1965

Hillside

36

20

None

17

Feb -1965

Hilltop

30

25

9

18

Reported

Hillside

48

33

None

24.2

Feb -1965

do

36

30.4

None

23.7

Feb -1965

Flat

6

200

34.5

20

Reported

7

Hillside

6

155

33.5

30

do

30

Hilltop

30

Hillside

48

do

60

do

36

Flat

60

28

28

22

do

25.3

None

20.6

Feb -1965

16

None

10.8

Feb -1965

32.9

None

20.1

Feb -1965

14.5

None

8.9

Feb -1965

Hillside do do do
Hilltop do
Flat Hilltop

48

23

36

14

6

202

8

350

8

550

10

410

48

16.3

48

48.7

None None 58
34 103.5 None None

13.2 7.5
30 160 113
60 7.4
39.2

Feb -1965

Feb -1965

Reported

35

do

90

do

120

do

348

Feb -1965

Feb -1965

8

Use

Remarks

Domestic & stock do do do
Domestic Domestic & stock Domestic
do Domestic & stock
do Domestic
do Domestic & stock Domestic
do do

do do None Domestic do
Domestic & stock Domestic Domestic & stock None Public supply None Domestic & stock
do

Goes dry every summer.
High iron content.
Standby well.
Some iron.

Well No.

Owner

14CC 1

2 3 4 5 6 7 8 14DD 1

2

3

4

I-<

~

5

6

7

8

9

Highland Golf Club Inc. do do
B. K. Hammond H. W. Lytle
Miss Nidia Gardner Gordon Dean E. 0. Brock
Hi Roc Development Corp. do
Parks Printing Co. do do
Roy Staples Billy Farmer James Pickard J. A. Cowan

10 Highland Golf Club

11

H. L. Maynor

12

T. D. Watson

13 L. F. Robinson, Jr.

14

R. L. Mims

15

Jesse Costley

16

J. W. Kincaid

17

T. L. Brooks

18

Green Meadows

Memorial Garden

19

W. E. Singleton

Type of
well
Drilled
do do do do do do Dug
Drilled do do do do
Bored Drilled Dug Bored
Drilled Dug
Bored Dug Bored Dug
do Bored Drilled
Dug

Table 4.-Record of wells in Rockdale CO'Unty, Georgia (continued).

Topography

Diameter of well Depth (inches) (feet)

Cased to (feet)

Water-level
below land surface (feet)

Date measured

Yield (gpm)

Hillside

6

385

60

20

Reported

28

do

6

307

9

do

6

Draw

6

80

29

25

Reported

9

Hillside

6

145

42.5

40

do

6

do

6

195

42

Hilltop

6

342

38

30

Reported

6.5

Hillside

36

40

None

32

do

Valley

6

do

6

do

10

do

10

Hilltop

10

do

30

Hillside

6

Hilltop

36

Hillside

30

Depression 6

Hillside

36

Hilltop

24

Flat land 30

do

30

Hilltop

36

Ridgetop

36

Hillside

30

do

6

405 130 550 237 600
55 137
37.6 42
247 41
48 19.7 10.9 58 63 40 146

1 106
30
55 51 None
65 None
48 None
10.9 None None 40 19

100

25

Oct -1947

60

6

Dec -1950

75

55

Oct -1947

20

18

May -1964

4

26.8

May-1964

25

Reported

1962

35

Reported

1963

18

July -1964

9

July -1964

6.7

July -1964

46.2

July -1964

43.8

July -1964

25

Reported

21

do

12

Hillside

36

34

None

30

Reported

Use

Remarks

Golf course

Domestic do
None Stock Domestic

Supply inadequate. Do.
Do.

None Public supply None Industrial None Domestic Domestic & stock
do Domestic

Do. High iron content.

None Domestic

Supply inadequate.

do do do do do do Cemetery

Domestic

Well No.

Owner

Type
of well

14DD20

21

22

23

24

25

26

27

28

29

30

31

32

I-'

33

-::J

34

35

36

37

38

39

40

41

42

43

44

45

46 47

48 49 14EE 1

S. C. Herring H. R. Payne Charles I. Goodwin Mrs. Manley Larry D. Bradley J. L. Miller, Jr. John Steincher W. E. Brown Alfred Marshall A. R. Barksdale Roy Hightower H. K. Costley
do Miss Eva Costley
Calvin Thomas E. J. Parker
Grace McGettie J. C. Haynes
Estate of Gene Smith J. M. Mitcham Grover Thomas W. K. Farmer John Black
Milton Sheppard Leon Shaw
American Tel. & Tel. Co. do
Moonlit Drive-in Theater do
Mrs. Violet M. Edwards Gwinnett Cox

Drilled do
Dug do
Drilled Bored Drilled
do do Dug do do do do do do do do do Drilled do Dug do do do Drilled
do do
do do do

Table 4.-Record of wells in Rockdale CrYUnty, Georgia (continued).

Topography

Diameter 0 f well Depth (inches) (feet)

Cased to (feet)

Water-level below land
surface (feet)

Date measured

Yield (gpm)

Hilltop do
Hillside do
Flat Hillside Hilltop
do do Hillside do do do do Hilltop Draw Hillside Hilltop do Hillside do do do Hilltop Hillside Flat

6

206

6

36

46

36

20.6

6

347

36

40

6

108

6

300

6

165

36

41

30

40

48

32

36

32

36

62

36

39.5

36

27.5

48

13

36

55

30

25.5

36

50

6

338

36

15.9

36

19.5

36

46

36

38 .1

8

700

55

12

Reported

8

None

33.5 Sept -1964

None

16.8

Jan -1965

40

46

Reported

1.5

40

11

do

70

20

do

60

41

60

do

8

20

25

do

4

None

36

Feb -1965

40

25

Reported

9

7

Feb -1965

10

None

4.5

Feb -1965

None

54

Reported

9

30.5

Feb -1965

None

4.5

Feb -1965

None

9.5

Feb -1965

None

42.7

Feb -1965

25.5

23.9

Feb -1965

None

42

Feb -1965

30

35

Reported

None

14.6

Feb -1965

9

14.5

Feb -1965

None

42.1

Feb -1965

None

24.7

Feb -1965

106

45

Reported

32

do Hilltop

8

700

105

34

6

400

80

30

do

28

do

30

do Slope Hilltop

6

300

6

240

6

125

85

30

92.5

8

31

do

10

12

Reported

60

Use

Remarks

Domestic Domestic & stock
do Domestic
do do do Domestic & stock Domestic Domestic & stock Domestic Domestic & stock None Domestic do do do do do Domestic & stock Domestic Domestic & stock Domestic Domestic & stock do Industrial

High iron content.
Water milky. Do.
High iron content. Water milky.

do Drinking

do Trailer park Domestic

Some iron.

GEORGIA DEPARTMENT OF MINESt,MINING, AND GEOLOGY GEOLOGICAL SuRVEY

E X p LAN A

Alluvium Strea m depo si ted sand and gravel
D
Diaba se dike

Pegmatite
r ::pgr : :1

Porphyritic

Pano la Gra ni te of Herrmann (1954)
gr ani te composed of micro cline, quartz, oli goclase, and biotite
rjb(J

T
a>:az<:( w ~
:::>
0

0 N
Contac t Long-dashed where approxima tely located;
short-dashed where inferred; dotted where conce a Ied

H . f-
z 3: 0 z z:>:::
:::>
w
(!) <(

X
Pavemen t
2
Well
54
0....
Sp r i ng

Porphyrob lastic biotite gneiss
Includes parphyroblastic bio tite gneiss with inter laye red nonmappable uni ts of fine - grained biotite gneiss, sil l imanite -q uartz schist, muscovi t e-biot ite schist, phlogopi t e quartzite, and amphibo1 ite gneiss. Numerous non mappable pegma tite and quartz ve ins

~ ~

Amphibo I ite gneiss

Amphibolite

- gneiss with interlayered biotite gneiss and Muscovi te quartz ite

biotite schist

l\:".
z
<(
a:
(!)
2
<(

l nte r layered wit hin garnet mic a schist

w 0

a:
Q_

0

Garnet mica schist Includes garnet mica sch ist, fine-gra ined bio t ite gneiss, and
amphibolite gneiss. Numerous nonmappable pegmatite and quartz veins
jrgn . .,
Lithon ia Gneiss of Watson (1902) Contorted bi otite gneiss that has been migmatize d by injec ti on of
apl ite and peg matite dikes.

INFORMATION CIRCULAR 33
PLATE I

/
/
/

< l' 0

0 0

0
N

8400'

8400'
13EE

Prepared in cooperation with the U.S. Geological Survey, Water Resources Division

SCALE.. 1.62,50 0

I

0

I

UI _LliLT J

T

2 MILES

12CC'

1400
)
I
,
14CC

- - ----L_ _ _ __[_____ _ __ J 3330 '
WEL L-LOCAT I ON INDEX

Base map compiled f ro m U.S. Geological Su r vey and Corps of Eng in ee r s, U.S. Army 7f- -minute quadrangle maps

Geo logy by M. J. McCollum, 1964

Map of Rockdale County, Georgia showing geology and location of wells and spnngs.