HYDROGEOLOGY OF THE DUBLIN AND MIDVILLE AQUIFER SYSTEMS OF EAST-CENTRAL GEORGIA JohnS. Clarke, Rebekah Brooks, and Robert E. Faye B-Aquller discharge to streams In vicinity of well EXPLA NAT I ON AQUIFER CHANNEL SANDS CONFINING ZONE. SANDY CONF INING ZO NE CL AY L ENS WAl"ER LEVEL DIRECTION OF GAOUNO- WATEfl FLOW Prepared as part of the Accelerated Ground-Water Program in cooperation with the DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY DEPARTMENT OF NATURAL RESOURCES ENVIRONMENTAL PROTECTION DIVISION GEORGIA GEOLOGIC SURVEY INFORMATION CIRCULAR 74 Geologic Units In this report, for the purpose of simplicity, formations of Late Cretaceous and Paleocene age that are present in the study area and have similar lithologies and(or) equivalent stratigraphic positions, are grouped into informal geologic units. Some informal geologic units were assigned names taken from geologic formations of equivalent age from adjacent areas. For example the Peedee-Providence unit consists of age equivalents of the Peedee Formation in western South Carolina, and the Providence Sand in western Georgia. Although the informal geologic units are age equivalents of the formations, they are not necessarily lithostratigraphic equivalents. COVER PHOTO: Schematic diagram of recharge and discharge, and the direction of ground-water flow in the Gordon, Dublin, Midville, and Dublin-Midville aquifer systems. HYDROGEOLOGY OF THE DUBLIN AND MIDVILLE AQUIFER SYSTEMS OF EAST-CENTRAL GEORGIA By John S. Clarke, Rebekah Brooks, and Robert E. Faye Prepared as part of the Accelerated Ground-Water Program in cooperation with the Department of the Interior u.s. Geological Survey Department of Natural Resources J. Leonard Ledbetter, Commissioner Environmental Protection Division Harold F. Reheis, Assistant Director Georgia Geologic Survey William H. McLemore, State Geologist Atlanta, Georgia 1985 INFORMATION CIRCULAR 74 TABLE OF CONTENTS Abstract ................................... .... . ............ ....... . Introduction .................... . Purpose and Scope ..................... . Method of study ..................... . Test-well drilling program Well-numbering system.. ................................ .. . Previous studies ................................................. . Acknowledgments ............................... .......... Geology . ..................... .... General setting .................................................. Depositional environments ...... Geologic units ..................................... Upper Cretaceous . ............................. Cape Fear unit . ..... ~ , ................... Middendorf-Blufftown unit Black Creek-Cusseta unit Peedee-Providence unit .................... ...................... Paleocene . .................... .. Lower Huber-Ellenton unit . .. Baker Hill-Nanafalia unit . ....... . Post-Paleocene Channel sands ... .......................... Structure ........................................................ . Hydrology ......................... . Aquifer systems ...................................... Definition ................................. Dublin aquifer system...................... Midville aquifer system Dublin-Midville aquifer system Altitude of tops of aquifer systems and confining units Thickness and sand content . .......................... Aquifer and well properties Specific capacitY Transmissivity ......................................... Hydraulic conductivity Yield .................................................. . Ground-water levels .... ......................................... Seasonal and long-term fluctuations Potentiometric surface ... Estimated 1944-50 potentiometric surface October 1980 potentiometric surface Mine dewatering operations Long-term water-level declines Recharge ..................................... Discharge .................................. Water use ....................................... Well construction ................................. Water quality ..................................... Summary . ........ Page 1 1 2 2 4 4 4 6 6 6 7 10 10 10 12 12 13 13 13 13 14 14 14 15 15 15 16 16 17 17 17 22 22 22 26 28 28 28 31 35 35 35 36 36 39 39 39 43 47 iii TABLE OF CONr ENr S--Continued Page Selected references 47 Appendices. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 52 Appendix A.--Record of selected wells.......................... 52 Appendix B.--Water-quality analyses for the Dublin, Midville, and Dublin-Midville aquifer systems............. 60 Lisr OF ILLUsr RAT IONS Page Figure 1. Map showing location of study area, physiographic provinces, and areas covered by investigations as part of the Upper Cretaceous-lower Tertiary aquifer study................................................ 3 2. Map showing number and letter designations for 7.5-minute topographic quadrangles covering east-central Georgia. 5 3. Map showing locations of selected wells and hydrogeologic sections in east-central Georgia....... 8 4. Schematic diagram showing deltaic depositional environments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Figures 5-10. Map showing: 5. Structural features, outcrop area, and altitude of the top of the Dublin and Dublin-Midville aquifer systems........................................... 18 6. Altitude of the top of the Midville aquifer system... 19 7. Altitude of the top of the Black Creek-Cusseta confining unit.................................... 20 8. Structural features and altitude of the base of the Midville and Dublin-Midville aquifer systems 21 9. Thickness and percentage of sand in the Dublin and Dublin-Midville aquifer systems 23 10. Thickness and percentage of sand in the Midville and Dublin-Midville aquifer systems 24 Figure 11. Graph showing comparison of observed transmissivity computed from time-drawdown or time-recovery data with estimated transmissivity computed from equation(!).......................................... 26 Figure 12. Map showing estimated transmissivity of the Dublin, Mid- ville, and Dublin-Midville aquifer systems 27 Figures 13-17. Hydrographs showing: 13~ Mean monthly water levels in the Dublin-Midville aquifer system at well 30AA4, and the cumulative departure of precipitation at National Weather Service station 090495, Richmond County, 1979-81............................................ 29 14. Mean monthly water levels in the Jacksonian aquifer at well 21T1, Laurens County, 1973-82.............. 29 15. Water-level fluctuations in wells 18Ul and 18U2, Twiggs County, and the cumulative departure of precipitation at National Weather Service sta- tion 095443, Bibb County, 1975-82.................. 30 iv LIST OF ILLUSTRATIONS--Continued Page Figures 16-17. Hydrographs showing--Continued: 16. Mean monthly water levels in the Midville aquifer system at well 28X1, Burke County, 1980-84 30 17. Mean monthly water levels in the Midville aquifer system at well 24V1, Johnson County, 1980-84 30 Figure 18. Map showing estimated potentiometric surface of the Dublin and Dublin-Midville aquifer systems, 1944-50 32 19. Map showing potentiometric surface of the Dublin and Dublin-Midville aquifer systems, October 1980 33 20. Diagram showing head difference between the Dublin and Midville aquifer systems in Twiggs and Laurens Coun- ties and between the Gordon and Midville aquifer systems in Burke CountY 34 21. Maps showing Huber Corporation mine dewatering operation and its effect on ground-water flow, central Twiggs County, 1968-72....................................... 37 22. Map showing location of water-level monitoring wells and water-level declines in the Midville and Dublin- Midville aquifer systems, 1950-80 38 23. Schematic diagram of recharge and discharge, and the direction of ground-water flow in the Gordon, Dublin, Midville, and Dublin-Midville aquifer systems 40 Figure 24. Map showing estimated ground-water discharge to streams from aquifers in east-central Georgia, October- November 19 54. . . . . . . . . . . . . . . . . . . . . . . . . . 41 25. Graph showing Georgia kaolin production, 1900-1980 43 26. Diagram showing well construction and lithologic and geophysical properties of aquifer sediments at well 16U1, near Warner Robins, Houston County 44 27. Map showing dissolved-solids concentration of water from the Dublin, Midville, and Dublin-Midville aquifer systems, 1940-82 45 28. Map showing iron concentration and pH of water from the Dublin, Midville, and Dublin-Midville aquifer systems, 1952-82...................................... 46 v Plate Plate PLATES In pocket 1. Hydrogeologic sections A-A' and B-B'. 2. Hydrogeologic sections C-C', D-D', and list of wells shown on hydrogeologic sections. Table 1. 2. 3. 4. TABLES Page Generalized correlation of geologic and hydrologic units of Late Cretaceous and Tertiary age in Georgia 11 Aquifer properties at wells in which aquifer tests were conducted ............................................ 25 Hydraulic conductivity of sediments cored at well 24V1, near Wrightsville, Johnson County 28 Estimated water use from the Dublin, Midville, and Dublin- Midville aquifer systems, 1980 42 vi CONVERSION FACTORS For use of readers who prefer to use SI (metric) units, conversion factors for terms used in this report are listed below: Multiply foot (ft) ~ 0.3048 To obtain meter (m) inch (in.) 25.4 millimeter (mm) mile (mi) 1.609 kilometer (km) Area square mile (mi2) 2.590 square kilometer (km2) Flow gallon per minute (gal/min) 0.06309 liter per second (1/s) million gallons per day (Mgal/d) 0.04381 43.81 cubic meters per second (m3/s) liter per second (1/s) Concentration part per million 1 1000 milligrams per liter (mg/1) micrograms per liter (~g/1) Transmissivity foot s~uared per day (ft /d) 0.0929 meter squared per day (m2/d) Specific capacity gallon per minute per foot [(gal/min)/ft] 0.207 liter per second per meter [(1/s)/m] Specific conductance micromho per centimeter 1 at 25 Celsius (~mhos/em at 25C) microsiemens per centimeter at 25 Celsius (~S/cm at 25C) degrees Fahrenheit (F) degrees Celsius (C) Temperatures 5/9(F-32) 9/5(C+32) degrees Celsius (C) degrees Fahrenheit (F) vii HYDROGEOLOGY OF THE DUBLIN AND MIDVILLE AQUIFER SYSTEMS OF EAST-CENTRAL GEORGIA By John S. Clarke, Rebekah Brooks, and Robert E. Faye ABSTRACT During 1980, an estimated 121 million gallons of water per day was pumped in a 26-county area in east-central Georgia from sand aquifers of Paleocene and Late Cretaceous age. Maximum withdrawals were at the kaolin mining and processing centers in Twiggs, Wilkinson, and Washington Counties, where water levels have declined as much as 50 feet since 1944-50. In the southern two-thirds of the study area, water levels have shown little, if any, change. Declining water levels and increasing competition for ground water have caused concern over the adequacy of ground-water supplies. This report defines the areal extent and describes the hydrogeology of the Paleocene-Upper Cretaceous aquifers of east-central Georgia, and evaluates the effects of man on the ground-water flow system. Hydrogeologic data from four test wells indicate that the aquifers consist of alternating layers of sand and clay that are largely of deltaic origin. The aquifers contain discontinuous confining units of clay and silt that are believed to extend for only short distances and are not significant in a regional evaluation. For this reason, the aquifers were grouped into two regional aquifer systems that are bounded by three regional confining units. The Dublin and Midville aquifer systems were each named for a geographic feature near a test well that penetrates sediments which are representative of the geologic and hydrologic characteristics of the aquifer system. In the northern third of the study area, the confining unit between the Dublin and Midville aquifer systems is absent and the aquifer systems combine to form the Dublin-Midville aquifer system. The aquifer systems range in thickness from 80 to 645 feet and their transmissivities range from 800 to 39,000 feet squared per day. The hydraulic conductivity ranges from 15 to 530 feet per day. Wells yield as much as 3, 400 gallons per minute. Chemical analyses of water from 49 wells indicate that watel." from both aquifer systems is of good quality except in the central part of the study area, where iron concentrations are as high as 6,700 micrograms per liter and exceed the 300 micrograms per liter recommended limit for drinking water. The principal recharge to the aquifer systems is from precipitation that occurs within and adjacent to the outcrop areas. The principal discharge is to streams in the outcrop area, although in the southern part of the study area, discharge occurs by leakage into overlying units. INTRODUCTION In east-central Georgia, sand aquifers of Paleocene and Late Cretaceous age yielded an estimated 121 Mgal/d during 1980. About 60 percent of this withdrawal was at the kaolin mining and processing centers in Twiggs, Wilkinson, and Washington Counties. At these centers, water levels have declined as much as 50 ft since 1944-50. Concern over declining water levels, together with increasing 1 competition for ground-water resources between municipal, industrial, and agricultural users, spurred interest in evaluating available supplies of ground water. An understanding of the hydrogeologic properties of the aquifer systems is important for effective management of the ground-water resources. This study was conducted by the U.S. Geological Survey in cooperation with the Georgia Department of Natural Resources, Environmental Protection Division, Geologic Survey Branch. This report is one in a series presenting the results of studies being conducted on the lower Tertiary-Upper Cretaceous aquifers in the Georgia Coastal Plain as part of the Georgia Accelerated Ground-Water Program. Two previous reports described aquifers in s .outhwestern Georgia, whereas this report is one of three that describe aquifers in east-central Georgia (fig. 1). Purpose and Scope The purpose of this report is to define the areal extent and describe the hydrology and geology of the PaleoceneUpper Cretaceous aquifers of east~central Georgia. The effects of man on the ground-water-flow system were also evaluated. The 26-county study area covers 9,200 mi2 and is generally bounded to the east by the Savannah River, to the west by the Ocmulgee River, and to the north by the Fall Line (fig. 1). Methods of Study With the exception of the southern part ' of the study area, data resources for the study were comprehensive. Data were obtained from published reports, consultant's reports, from files of the U.S. Geological Survey and the Georgia Geologic Survey, water-use and waterquality files of the Georgia Environmental Protection Division, and local industries and municipalities. Borehole geophysical logs, and lithologic and paleontologic data were obtain- ed from Herrick (1961) and from files of the U.S. Geological Survey, the Georgia Geologic Survey, and the Georgia Environmental Protection Division. These data, supplemented by data from four test wells, were used to construct hydrogeologic sections and maps showing the areal extent and the approximate top, base, and thickness of the two aquifer systems that were delineated. Water levels measured in more than 80 wells during October 20-24, 1980, were used to construct a map showing the configuration of the potentiometric surface. Water-level data from reports by LaMoreaux (1946), LeGrand and Furcron (1956), and LeGrand (1962) were used to prepare a map showing the configuration of the potentiometric surface for the period 194450. Until recently, topographic maps were not available to accurately locate and determine the latitude and longitude of the wells listed in these reports. Because this information was crucial for the construction of accurate potentiometric maps, plots of well locations were transferred from original field maps onto more accurate U.S. Geological Survey 7.5minute topographic quadrangle maps and were field checked, where possible. The data were used to construct a map showing the configuration of the potentiometric surface during 1944-50. Water-level declines were then estimated by comparing the 1944-50 and October 1980 potentiometric surfaces. Continuous water-level recorders were installed on seven wells to monitor water-level fluctuations and long-term water-level trends. During the investigation, water samples for chemical analysis were obtained from four test wells and from two other wells. Data from these analyses together with historical data from 43 additional wells were used to map areal trends in pH, and in dissolved-solids and iron concentrations. Aquifer transmissivity was computed from time-drawdown and time-recovery data collected from the four test wells, and from published and unpublished aquifer- 2 .. l -fCO ' YA''L L E Y W wr rt t A.t.io -, 'D ll RIDGE l l. .. l,tl u ~' IDG~ -y " ..._ (I s.vru .I n" lTJ'H 5 "' .r. ;.~o~r. \ ' t.llll I 1 ~ ,,. ll"iU'r f. . 0 ~~~, ~ '" n ,.' ~ \I~,,Q - ~ ~ - f_ 1.. 011E't Ovl IIGR:H:. l ~ .. .\ Olj'H " .~1,. ~cw' ' ) EXPLANATION AREA OF REPORT Hydrogeology of the Dublin and Midville aquifer systems of east-central Georgia (this report) Hydrogeology of the Gordon aquirer system of eastcentral Georgia (Brooks and olhers, 1985) Hydrogeology of the Clayton aquifer of southwest Georgia (Clarke and olhers, 1984) Hydrogeology of the Providence aquifer of southwesl Georgia (Clarke and others, 1983) ~ L;~ Geohydrology of the Jacksonian aquifer in central and east-cenlral Georgia (Vincent, 1982) Where study areas overlap, 2 or more palterns are shown \ ~ IH) U r 33 ' I. It flit!!. 10 It\ E ,. ~-. '"\; ( tf ,_, R,. I L t ... rttU.AS ... -----L~- g- f'f ~ ,,. ~ll , 4"~ 14 11 c 0\4" tOt "0 s .... I I' Figure 1.-Location of study a rea, physiographic provinces, and areas covered by investigations as part of the Upper Cretaceous-lower Tertiary aquifer study. 3 test and specific-capacity data. Transmissivity values were mapped to show areal trends. Permeameter analyses of core samples collected at well 24V1 were used to estimate the vertical and horizontal hydraulic conductivity of confining units. Aquifer hydraulic conductivity was estimated from aquifer-test data. Ground-water-use data for municipal!ties and industries were obtained from water-use reports submitted quarterly to the Georgia Environmental Protection Division. Agricultural water-use data were obtained from water-use surveys sponsored by the U.S. Geological Survey and conducted by the U.S. Soil Conservation Service during 1979-80. Test-Well Drilling Program Because of insufficient geologic, hydrologic, and water-quality data in the southern half of the study area, four test wells were drilled during 1980 and 1981 as part of this study (fig. 3). The wells are near Midville, in Burke County (28X1); near Wrightsville, in Johnson County (24V1); near Dublin, in Laurens County (21U4); and in northern Pulaski County (18T1), along a line that approximately parallels the strike of the strata. Each of the wells completely penetrated Tertiary strata and all except well 18T1 completely penetrated Upper Cretaceous strata. Drill cuttings, cores, paleontologic samples, and geophysical logs were obtained from each well and were used to correlate geologic units, aquifers, and confining units. Each of the four test wells was screened in Upper Cretaceous strata (pls. 1 and 2). After completion of each well, water samples were collected for chemical analysis and water-level recorders were installed. These wells are now part of statewide ground-water-level and groundwater-quality monitoring networks. Well-Numbering System With the exception of wells in South Carolina, wells in this report are numbered according to a system based on the U.S. Geological Survey Index to Topographic Maps of Georgia (fig. 2). Each 7. 5-minute topographic quadrangle in the State has been given a number and letter designation beginning at the southwest corner of the State. Numbers increase eastward and letters increase alphabetically northward. The letters "I" and "0" are omitted. Quadrangles in the northern part of the State are designated by double letters. Wells inventoried in each quadrangle are numbered consecutively beginning with 1. Thus, the fourth well scheduled in the Sandersville quadrangle in Washington County is designated 22X4. In areas where modern water-level data were unavailable, wells were used from Georgia Geological Survey reports (LaMoreaux, 1946; LeGrand and Furcron, 1956; and LeGrand, 1962). Because these wells are not included in the modern data base and thus were not assigned grid numbers, the sequential well numbers from the reports were retained. In South Carolina, wells are designated by letters prefixing sequential well numbers as follows: SRP, Savannah River Plant; AK, Aiken County; AL, Allendale County; and VSC, Plant Vogtle, SC. Additional information regarding wells used in this report may be obtained by referring to the well identification number in any correspondence to the District Chief, U.S. Geological Survey, 6481-B Peachtree Industrial Boulevard, Doraville, Ga. 30360. Previous Studies Previous reports about the study area include descriptions of t\J.e geology and ground-water resources of Baldwin, Hancock, Jones, Twiggs, Washington, and Wilkinson Counties (LaMoreaux, 1946); Burke, 4 83 '0 82 BB AA z y v p .~. 15 16 17 18 19 20 21 22 23 24 25 26 27 2 8 29 30 31 32 33 34 Modified from index to topographic maps of Georgia U.S , Geological Survey 0 10 20 30 40 MILES Figure 2.-Number and letter designations for 7.5-minute topographic quadrangles covering east-central Georgia. 5 Columbia, Glascock, Jefferson, McDuffie, Richmond, and Warren Counties (LeGrand and Furcron, 1956); and Bibb, Crawford, Houston, Macon, Peach, Schley, and Taylor Counties (LeGrand, 1962). The three reports include descriptions of drill cuttings and outcropping sediments, and tables listing well-construction, waterlevel, well-yield, and water-quality data. Pollard and Vorhis (1980) described the geohydrology of the Cretaceous aquifer system in southern Georgia. That report includes hydrogeologic sections and maps showing the altitude of the tops of the aquifers and their approximate thicknesses. Siple (1967), in a comprehensive study, described the geology and groundwater resources of the Savannah River Plant, S.C., near the Georgia-South Carolina border. The effects of suspected Late Cretaceous and Cenozoic faulting on ground-water flow near the Savannah River in Georgia and South Carolina were evaluated by Faye and Prowell (1982). As part of a series of reports on the lower Tertiary-Upper Cretaceous aquifers in Georgia, Vincent (1982) described the geohydrology of the Jacksonian aquifer in the study area and Clarke and others ( 1983; 1984) described the hydrogeology of the Providence aquifer and the Clayton aquifer in southwest Georgia, including Housston and Pulaski Counties (fig. 1). Geologic reports describing the study area include maps showing the geology and mineral resources of the Macon-Gordon kaolin district in Twiggs and western Wilkinson Counties (Buie and others, 1979), and the geology of the central Georgia kaolin district in Wilkinson, Washington, Baldwin, and Hancock Counties (Hetrick and Fridel!, 1983, part I). Prowell and others (1985) correlated geologic units along a line extending across the central part of the study area, providing stratigraphic correlations between western and eastern Georgia and western South Carolina based on new data from the test wells drilled as part of the present study. Herrick (1961) presented litho- logic logs and paleontologic data from wells throughout the Coastal Plain of Georgia. Guidebooks describing outcropping sediments in the study area include: Herrick and Counts (1968), Pickering (1971), and Huddlestun and others (1974). Other hydrologic and geologic reports are listed in Selected References. Acknowledgments The authors extend their appreciation to the many well owners, drillers, and managers of municipal and industrial waterworks who readily furnished information about wells. In particular, the writers wish to thank Douglas M. Dangerfield of M. R. Chasman and Associates, Athens, Ga.; Gerald S. Grainger of the Southern Company, Birmingham, Ala; Robert Massey of Layne-Atlantic Company, Savannah, Ga.; Sam M. Pickering of Yara Engineering, Deepstep, Ga.; and Dan Zeigler of Southeast Exploration and Production Company, Dallas, Tex, for providing hydrologic and geologic data. Conway Mizelle of Insurance Services of Georgia provided historical records of municipal water use in the study area. Lin D. Pollard, u.s. Geological Sur- vey, organized and monitored the testwell-drilling program. Laurel M. Bybell, Raymond A. Cristopher, Lucy E. Edwards, and Norman 0. Frederiksen, u.s. Geologi- cal Survey, identified fossils in core samples from the test wells. The writers extend particular appreciation and ac- knowledgment to David C. Prowell, u.s. Geological Survey, for his invaluable advice and assistance regarding the correlation of lithologic and stratigraphic units within the study area. Special appreciation is extended to Willis G. Hester and Ellie R. Black for preparing the illustrations in this report. GEOLOGY General Setting Coastal Plain sedimentary rocks within the study area (fig. 1) consist of alter- 6 nating layers of sand, clay, and limestone that range in age from Late Cretaceous through Holocene. These strata dip and progressively thicken to the southeast, reaching a maximum thickness of at least 3, 000 ft in the southern part of the study area. The approximate northern limit of the strata and the contact between the Coastal Plain and Piedmont physiographic provinces is marked by the Fall Line (fig. 1). The strata crop out in discontinuous belts that are generally parallel to the Fall Line (fig. 3). The sedimentary sequence unconformably overlies igneous and metamorphic rocks of Paleozoic age, and consolidated red beds of early Mesozoic age (Chowns and Williams, 1983). The age and stratigraphic correlations of geologic units in east-central Georgia long have been controversial because fossil evidence is sparse, lithologies of adjacent units are commonly similar, and some units can only be observed in drill cuttings. For example, certain strata in the study area that were assigned by early workers to the Upper Cretaceous. Tuscaloosa Formation have recently been shown by palynologic and stratigraphic studies to be of younger Cretaceous and Tertiary age (Tschudy and Patterson, 1975, p. 434, 437). According to David C. Prowell (U.S. Geological Survey, written commun., 1982), the Tuscaloosa Formation and unnamed rocks of equivalent age are absent in most of the study area, except possibly in southern Pulaski and Treutlen Counties. Sediments of Late Cretaceous and Tertiary age in east-central Georgia commonly contain thick lenses of kaolin. These lenses grade from deposits of relatively pure kaolin having economic importance into clayey sand. The origin of the kaolin is controversial, but it is generally agreed that the kaolin was derived from the weathering of crystalline rocks of the Piedmont physiographic province (fig. 1) and probably was deposited in a deltaic environment (Kesler, 1963, P 10). Kaolin is useful in distinguising sediments of Late Cretaceous age from sediments of Tertiary age. According to Ret- rick and Friddell (1983, part II), kaolin of Tertiary age may be distinguished by physical hardness; a very faint, greenish-gray cast; irregular fractures; and the presence of Panolites (a type of burrow). Kaolin of Late Cretaceous age is soft, white to pale tan, and has a conchoidal fracture and a high mica content. Depositional Environments The depositional environments of sediments in the study area controlled the distibution and types of lithologies that accumulated and thus effected the hydrologic properties of the sediments. In the study area, sediments of Late Cretaceous age were deposited mainly in deltaic environments where sediment-laden rivers and streams entered la~er bodies of water. Deltaic depositional environments are characterized by three principal subenvironments, in seaward order: the delta plain, the delta front, and the prodelta (fig. 4). The delta plain is the level or nearly level surface composing the most landward part of a large delta (fig. 4). The lower delta plain shows some tidal marine influence, whereas the upper delta plain shows little, if any, tidal influence. On the delta plain, sediment-laden rivers and streams deposit coarse permeable sand and clayey sand mostly within distributary channels. Interdistributary bays and marshes accumulate discontinuous deposits of clay and fine sand that are relatively impermeable. The delta front is a narrow zone seaward of the delta plain and within the effective depth of wave erosion. Deposition is most active in this subenvironment and sediments are chiefly interlayered silty sand, silt, and clay that generally become finer in texture in a seaward direction. The prodelta lies below the effective depth of wave erosion and marks the most seaward part of a delta. Sediments deposited in this fully marine subenvironment consist mostly of laminated clay and 7 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 EE EXPLANATION A-A' LINE OF HYDROGEOLOGIC S ECTION DDI P I14 NUMBER-LETTER COMBINATION INDICATES THE 1:24,000-SCALE MAP IDENTIFICATION FOR GEORGIA 2 WELL-Number is sequential well identification number located within each 1:24,000-scale map AA WELL AND IDENTIFICATION NUMBER FOR PREVIOUS REPORTS-Number is _, county sequential number. Well is not included in the number-letter 1 combination system listed above b7 LaMoreaux, 1946 o1-4 LeGrand and Furcron, 1956 ?8 LeGrand, 1962 AK-436 WELL lOCATED IN SOUTH CAROLINA-Number is well identification number z y lJ~ r~ . I ;- .. I_ -_~t-ao~;~.-- , ~~-- - ~06:~T~~~ X 32 33 34 35 36 37 EE DD cc BB - -- AA I _l-IZ I I IY X w 00 w v u :-1: .: T T s s j I~-~ $ R II L'" . I ~---- ... ,.. -t- ' ' I Q Q 32v !-...-_ !---~-- p p ~~a$:'e ~~~~ ~~p2,~~~~~08~0Sur~ey Figure 3.-Locations of selected wells and hydrogeologic sections in east-central Georgia. ~ ( j ( ? ('-......u m i t of t i d a I i nt I u e n c e \ ( ) ) Pre (de lta rocks A -shoreline -Seaward -Delta growth A' Pre-delta rock s Sea level - Delta growth EXPLANATION Delta plain Delta front Prodelta t"!~l-:1~i,~-~~~~E7.J.&~I Co11 r se clayey sand nnd discontinuous deposits ol clay and fine sand lnterlayered silly Laminated clay sand, silt. and and fine silt clay Figure 4,-Sc{lematic diagram showing deltaic depositional environments. 9 fine silt that are more laterally continuous than sediments deposited in delta front and delta plain environments. Geologic Units In this report, for the purpose of simplicity, formations of Late Cretaceous and Paleocene age that are present in the study area and have similar 1ithologies and(or) equivalent stratigraphic posi- tions, are grouped into informal geologic units (table 1). Some informal geologic units were assigned names taken from geo- logic formations of equivalent age from adjacent areas. For example, the Peedee- Providence unit consists of age equiv- alents of the Peedee Formation in western South Carolina, and the Providence Sand in western Georgia (table 1). Although the informal geologic units are age equi- valents of the formations, they are not necessarily lithostratigraphic equiva- lents. Geologic units in the study area include, in ascending order: the Cape Fear unit, the Middendorf-Blufftown unit, the Black Creek-Cusseta unit, the Peedee- Providence unit, the lower Huber-Ellenton unit, the Baker Hill-Nanafalia unit, and post-Paleocene units. The following lithostratigraphic descriptions are based on Prowell and others (1985). Upper Cretaceous Cape Fear unit The Cape Fear unit has a maximum known thickness of about 700 ft in the study area (well 25T2, pls. 1 and 2) and has been recognized in boreholes from western South Carolina to central Georgia (Prowell and others, 1985). In mast of the study area, the unit unconformably overlies pre-Cretaceous "basement" rock, although it is thought to locally overlie unnamed rocks equivalent to the Tuscaloosa Formation (table 1) in the extreme southern part of the study area in Pulaski and Treutlen Counties. The Cape Fear unit does not crop out in the study area and its northern limit is just north of well 19W6 on section B-B' (pl. 1), well 22Y30 on section C-C', and well SRP-P4A on section D-D' (pl. 2). The approximate northern limit of the Cape Fear unit is outlined on figure 8. The Cape Fear unit corresponds to the UK1 lithologic unit of Prowell and others ( 1985) which has been assigned an early Austinian age on the basis of fossil evidence in wells 18T1 and 21U4 (pl. 1). Sediments described in the present report as the Cape Fear unit at wells 23T1 and 25T2 (section B-B', pl. 1) were assigned by Mayer and Applin (1971, pl. 13) to the Tuscaloosa Formation of Eaglefordian age (table 1). The strata that Mayer and Applin identified as the Tuscaloosa Formation in this area were considered to be updip facies equivalents of the upper part of the Atkinson Formation, also considered by earlier workers to be of Eaglefordian age (Applin, 1955; Applin and Applin, 1967). Studies by Hazel (1969), Valentine (1982), and Owens and Gohn (1985) have redefined the age of the upper part of the Atkinson Formation as Austinian (table 1), which corresponds to the age assigned to the Cape Fear unit by Prowell and others (1985). Consequently, sediments assigned to the Cape Fear unit at wells 23T1 and 25T2 are thought to be Austinian in age and correlative with both the upper part of the Atkinson Formation of Mayer and Applin (1971) and the UK1 lithologic unit of Prowell and others (1985). Throughout most of the study area, the Cape Fear unit consists of poorly sorted, angular, fine to coarse sand admixed with kaolin that has a buff to pale-green cast and is commonly iron stained (pl. 1). In the northern part of its extent, the unit is semi-indurated owing to a large percentage of crystobalite cement. The Cape Fear unit is generally expressed on geophysical logs as a zone of low electrical resistivity (pls. 1 and 2). The lithology of the unit, together with a sparsity of marine organisms in core samples (Prowell and others, 1985), suggests that the Cape Fear unit,was deposited in an upper delta plain environment (fig. 4). 10 Table 1.-Generalized correlation of geologic and hydrologic units of Late Cretaceous and Tertiary age in Georgia. (Modified from Prowell and others, 1985) ~ERIE5 EUROPEAN STAGE PROVINCIAL STAGE w ALABAMA WESTERN GEORGIA E LITHOLOGIC UNIT EASTERN GEORGIA SOUTH CAROLINA w E GEOLOGIC UNIT THIS REPORT THICKNESS (FEET) HYDROLOGIC UNIT 'z" '0 " Undifterenli ated 0 " 'z" Chan ian '0 " 0 ,_ "' f-- ' -' 0 Rupe1ian Priabonian Bar1 onian Uz J UJ 0 ~ Lutetian Undifferentiated Chic kasawhayan Vicksburgian Jacksonian Claibornian l Paynes Hammock Sand Chickasawhay Fo rma lion Byram Forma tion "'-"Hlitl~ Lt-11111... R<.>d 61ull Cl~ 11 th.ulo4U .~J~ f.;;ufll~lhlll Ia~ Yazoo Cl y "' ~- ~t ~~ll"'r., Ftn Q.tu.avJ :t..s Lisc:.on Formation Ocala Limestone "'-,-..11t 4!!U1111 ,,.. ' Lisbon Formation I M1 Hawthorn Formation Hawthorn Formation I I ~U ,,,,...,,~~ I ;; I l!!.n.ru.tl a"d<;~or ~:~ .... Suwanee Limestone Cooper Formation (lt$.1111!y Nomt>ou) : I ~ I o, ~ I 5 I I 0-1000 I Eg ....., f-l~ ''mdlpl.l lolf!kiUII>I I _j n<';j!lfii Ll''ilfi"T."'d Barnwell Formation ur1..1o>IL ..(mb'l'nJ E7 ' IJ,~I IJ II I I I III Posl-Paleocene units r------- Jacksonian aquifer 2 1; ~1 w , Lisbon/Mc8ean McBe~n ") Santee Es E4 '"'""'""" ::::::::~ - - - ---r - - - - - - - - Confinir"'g unit .......... Yoresian Uz J Thanet ian UJ 0 0 UJ <-' Danian 0- Sabinian Midwayan Tallahal!a For!T)alion Tallaharra Formation f . - 'J - - _E_3__ _ 1 ~2 ""'-.u '-I'll ,_u. Ml"f'U 11181t"f"ll'l.llll F olt~ t\II IUI!'o!! ll rotmlll l iiHII T'l.u:.>O.!t.a!'lofl I'.., Mllf ll'! Il l 111 1 111 1 1111 ""' lllat au , wu .,.._ Nanalalia/Bker Hill fms.J p2 lll.l.l.l..l.llllllllllflllllllllllllllllllll .. N""'l~ ~, 1" 9 . ,,.,.,~:;.,." ,,..., ~ ao 11 1 t:. II C~ F:~ . o.,.;ojo ,.,_ I 111 1111 II Clayton Formation Clayton Formation P, ~~~:~~~~~:~~~~ II Huber Forma ti on Black Ming Forma li on Bl ack Mtngo Group Ellenton ... v .... N ,.,,,,,.n.,,,, Formation IIIII ti"I"''IIILI~ Baker Hill-Nanafalia unit Lower HuberEllenton unit 0 - 130 0-2 0 0 Gordon aquifer system 3 ----- Confining unit -- Dublin aquifer Maestrichtian Navarroan Ta y l ~ran I' r,,, ro ~ B lull C h d lk Ri pl ey Formation ' I Por.;."ldenoc,. StM Ripley Formation Demopolis Chalk Cusseta Sand UK6 UKs I I! I II 1 Peedee Formation Unnamed rocks Peedee-Providence unit " I 0- 380 system ------ UK4 Black Creek-Cusseta Black Creek Formation unit 0-240 Confining unit f--- - - - - - if) Campanian :::> 0 UJ 0 < 1- Santonian UJ a: Austinian Moore'/ i iJe Chalk Eutaw Formation Blufftown Formation Eutaw Formation UK 3 l l l llllll ll ll l ll l Unnamed rocks (Coastal areas) Middendorf-Biufftown unit 0-520 UK z 14fdoa,.4ort f Qr~ l lo n Middendorf Formalio n UK 1 Cape Fear Formalion Cape F@&r Forma lion Cape Fear un1t 0-700 0 Con i acian ffi 00- Turon i an :::> r-- ' ,_ Eaglefordian lll l ll l lll lllll ll ll lllll l llllllllll Tuscaloosa Fo rmation Tusca loo3D Form otio , lll lllllll llllllllllll l l lll l l l Unnamed rocks Unnamed rocks (Coastal areas) (Coastal areas) Midville aquifer system cOiiiriiin"':.;i,- - Cenomanian Woodbinian II 1 LaMoreaux {1946); Kesler (1963). 2 Vin cent (1982) 3 Bro oks and others ( 1985). In the southern part of the study area, the unit becomes less indurated and more sandy, and is expressed on geophysical logs by increased electrical resistivity at wells 23T1 and 25T2 (pl. 1). Changes in the lithologic character of the unit are also recognizable by changes in the drilling rate, and by sonic and lithologic logs at two oil-test wells (GGS 789 and GGS 964, Swanson and Gernazian, 1979) drilled near well 25T2. The transition from semi-indurated clayey sand in the north to poorly consolidated, cleaner sand in the south may be the result of lithologic changes during deposition or may reflect the southern limit of the crystobalite cementation process (D. C. Prowell, U.S. Geological Survey, oral commun., 1983). This transition begins between wells ' 24U1 and 23T1 on section B-B' (pl. 1) and between wells 24V1 and 25T2 on section C-C' (pl. 2). Middendorf-Blufftown unit The Middendorf-Blufftown unit has a maximum known thickness of about 520 ft in the study area (well 25T2, pl. 1) and includes strata that belong to the Middendorf Formation of eastern Georgia and western South Carolina and that are age equivalents of the Eutaw and Blufftown Formations of western Georgia, and the UKl, UK2, and UK3 lithologic units of Prowell and others (1985) (table 1). The unit overlies the Cape Fear unit and is distinguished by its lack of induration, better sorted sands, and carbonaceous character. The lower part of the MiddendorfBlufftown unit consists of poorly consolidated, angular to subangular, fine to very coarse sand containing silt and white to buff kaolin (section A-A', pl. 1). The upper part of the unit consists of alternating beds of silty clay and subangular, medium to coarse sand. These lithologies, and marine microfauna found in core samples (Prowell and others, 1985), suggest that the Middendorf-Blufftown unit was deposited in a delta plain environment under some marine influence (fig. 4). Black Creek-Cusseta unit The Black Creek-Cusseta unit has a maximum known thickness of about 240 ft in the study area (well 25T2, pl. 1), and includes strata that are age equivalents of the Black Creek Formation of western South Carolina, the Cusseta Sand of western Georgia, and the UK4 lithologic unit of Prowell and others (1985) (table 1). The unit unconformably overlies the Middendorf-Blufftown unit and is distinguished by its better sorted sands, finegrained character, and a relatively high clay content. In the southern two-thirds of the study area, the Black Creek-Cusseta unit consists of gray-green clayey silt and fine sand that is well sorted, very micaceous, carbonaceous, and locally glauconitic (section A-A.', pl. 1). In this area, the top of the unit can be distinguished on borehole geophysical logs as a zone of low electrical resistivity and high natural gamma radia'tion (pls. 1 and 2). These geophysical characteristics are typified by the wells shown on section A-A' (pl. 1). The Black CreekCusseta unit in the southern part of the study area was probably deposited in a delta front or prodelta environment, as indicated by its lithology and an abundance of marine macrofauna and microfauna (Prowell and others, 1985). The approximate northern limit of the prodelta or delta front deposits generally corresponds to the northern limit of the Black Creek-Cusseta confining unit (table 1) shown in figure 7. (See section on Aquifer Systems.) In the northern third of the study area, the Black Creek-Cusseta unit grades into clayey, fine to medium, subangular to subrounded quartz sand and silty clay that is moderately well sorted and contains thick, discontinuous, locally carbonaceous, kaolinitic clay beds. These lithologies are indicative of more landward deposition on the delta front and lower delta plain (fig. 4). Marine microfossils recognized in samples from northern areas, however, suggest a strong marine influence (Prowell and others, 1985). 12 The transition from fine-grained, prodelta or delta front deposits in the southern part of the area, to coarser grained, more landward deltaic deposits in the northern part of the area, is reflected by changing patterns on borehole geophysical logs (pls. 1 and 2). For example, along section B-B 1 (pl. 1), an increased percentage of sand in the unit is indicated by a general increase in electrical resistivity on log patterns in wells to the north. Peedee-Providence unit The Peedee-Providence unit is the youngest unit of Late Cretaceous age in the study area and has a maximum known thickness of about 380 ft (well 23T1, pl. 1). The unit includes strata that are age equivalents of the Peedee Formation in western South Carolina, the Ripley Formation and Providence Sand in western Georgia, and the UK5 and UK6 lithologic units of Prowell and others (1985) (table 1). The unit overlies the Black Creek-Cusseta unit and is distinguished from it by a higher percentage of sand, a lower percentage of glauconite, and on geophysical logs by higher electrical resistivity and lower natural gamma radiation (pls. 1 and 2). The lower part of the Peedee-Providence unit consists of well-sorted, wellrounded, fine to medium quartz sand, silt, and off-white to buff kaolin that contains thin beds of micaceous and highly carbonaceous clay (section A-A 1 , pl. 1). The upper part of the unit consists of silty kaolin and fine to medium sand that is subangular, moderately sorted, kaolinitic, and contains thin beds of coarse sand and gravel. The upper 20 to 40 ft of the unit commonly is an orangered weathered zone. These lithologies, and an abundance of marine microfauna (Prowell and others, 1985), suggest that the lower part of the Peedee-Providence unit was deposited in a marginal marine barrier complex. The upper part of the unit was deposited in a delta plain or marsh under some marine influence, as indicated by a sparsity of marine fossils. Paleocene Lower Huber-Ellenton unit The lower Huber-Ellenton unit unconformably overlies the Peedee-Providence unit and has a maximum known thickness of about 200 ft (well 25T2, pl. 1). The unit includes strata that are age equivalents of the Ellenton Formation in western South Carolina (Siple, 1967), the lower part of the Huber Formation in eastern Georgia (Buie and others, 1979), the Clayton and Porters Creek Formations in western Georgia (table 1), and the Pl lithologic unit of Prowell and. others (1985). The lower Huber-Ellenton unit consists of a basal layer of poorly sorted, silty, fine to coarse, angular, noncalcareous quartz sand containing varying percentages of kaolin, lignite, and mica (section A-A 1 , pl. 1). The remainder of the unit consists of locally carbonaceous, kaolinitic clay. The diversity of marine microfauna and these lithologies are indicative of deposition in a deltaic environment under marine influence. In the southern third of the study area, the unit is more calcareous and grades into relatively porous, mediumgray, glauconitic and highly fossiliferous limestone interlayered with fine to coarse sand and beds of calcareous clay. This lithofacies was identified in drill cuttings from well 25T2 (pl. 1) and is indicative of deposition in an open marine shelf environment that periodically received an influx of clastic sediment. Baker Hill-Nanafalia unit The Baker Hill-Nanafalia unit has a maximum known thickness of about 130 ft in the study area and includes strata that are age equivalents of the Black Mingo Formation in western South Carolina and the Tuscahoma, Nanafalia, and Baker Hill Formations (Gibson, 1982) in western Georgia (table 1). The unit overlies the lower Huber-Ellenton unit and is unconformably overlain by post-Paleocene 13 units. North of wells 20V4 (section B-B', pl. 1) and 24V1 (section C-C', pl. 2), the Baker Hill-Nanafalia unit is truncated by post-Paleocene units. The Baker Hill-Nanafalia unit is distinguished by a high percentage of clay and is characterized on borehole geophysical logs as a zone of high natural gamma radiation when compared to the overlying post-Paleocene units (pl. 1). In the northern two-thirds of the study area, the Baker Hill-Nanafalia unit consists of thin-bedded, medium to darkgray, silty, carbonaceous and kaolinitic clay (section A-A', pl. 1). An abundance of marine fauna suggest that the unit was deposited in a marginal marine (lagoonal to shallow shelf) environment. In the southern one-third of the study area, the Baker Hill-Nanafalia unit consists of gray-green, fine to medium, well-rounded, calcareous, quartz sand and interbedded limestone that is highly fossiliferous and glauconitic. These lithologies were observed in cuttings from wells AL-66 and AL-19 (section D-D', pl. 2), and suggest that here the unit was deposited in an open marine shallow shelf environment. Post-Paleocene acter than the underlying Cretaceous and Paleocene units and consist of alternating layers of sand, limestone, marl, and clay. For a more detailed discussion of post-Paleocene units, see Brooks and others (1985). Channel sands The channel sands (LaHoreaux, 1946) consist of discontinuous deposits of cross-bedded coarse sand, gravel, and kaolin fragments derived from underlying sediments and basement rock. These deposits fill ancient stream channels and range in thickness from a few inches to about 25 ft. The channel sands are present in northern Twiggs, Wilkinson, and Washington Counties, and in southern Jones, Baldwin, and Hancock Counties. The age of the channel sands is unknown, but LaHoreaux (1946) suggested that they might be of late Eocene age (table 1) as indicated by: (1) a gradational transition into sediments of Jacksonian age at some localities, and (2) their close association with onlapping Eocene strata. Kesler (1963), on the other hand, suggested that the Channel Sands might be a mixture of reworked sediments of Late Cretaceous to Miocene age that were redeposited during the. Pliocene Epoch. Post-Paleocene units in the study area range from Eocene to Hiocene in age and include strata that are the age equivalents of: (1) the Fishburne, Congaree, and Cooper Formations in western South Carolina; (2) the upper part of the Huber Formation, the Barnwell Formation, and the Suwannee Limestone in eastern Georgia; (3) the HcBean and Hawthorn Formations in western South Carolina and eastern Georgia; (4) the Tallahatta Formation, Hoodys Branch Formation, and Ocala Limestone of western Georgia; and (5) the Lisbon Formation that is recognizable throughout most of the Georgia Coastal Plain (table 1). The post-Paleocene units unconformably overlie the Baker HillNanafalia unit and have a maximum thickness of about 1, 000 ft (well 25T2, pl. 1). Over most of the study area, postPaleocene units are more marine in char- Structure Units of Late Cretaceous and Paleocene age in the study area generally dip to the southeast and strike to the north- east. Hajor structural features (fig. 5) reported in the study area include: the Belair fault (Prowell and O'Connor, 1978) and the Gulf Trough (Herrick and Vorhis 1963). ' The northeast-trending Belair fault crosses Burke, R1.tchhemonsdt,udyandar ea Co luimn biaJefCfoeursnotines' (fig. 5). The fault is a high-angle reverse fault, upthrown on the southeast side and has a maximum vertical displace- ment of 100 ft at the base of Coastal Plain strata (Prowell and O'Connor, 1978). 14 A projection of the northeast-trending Gulf Trough may cross the southeastern part of the study area into Bulloch and Screven Counties (Miller, 1982). The Gulf Trough has an adverse effect on the ground-water flow system, as evidenced by low well yields, low transmissivity, high dissolved-solids concentrations, and steepened potentiometric gradients in the Floridan aquifer system (formerly principal artesian aquifer) in southwestern Georgia (Zimmerman, 1977). It is likely that similar effects occur in the vicinity of the Gulf Trough in eastern Georgia. On the basis of what they considered to be anomalous potentiometric data, Faye and Prowell (1982) inferred that the Gulf Trough may extend into Bulloch and Screven Counties, which is farther northeastward than previously interpreted. A significant reduction in well yields and transmissivity (fig. 12) in the Dublin aquifer system between Dover, in Screven County, and Statesboro, in Bulloch County (wells 32U19 and 31Tll, Appendix A) may support the presence of the trough. (See section on Aquifer Properties.) Several different opinions as to the nature and origin of the Gulf Trough have been expressed by previous investigators. Patterson and Herrick (1971, p. ll-12) presented a summary of these differing views: (1) that the feature represents a buried submarine valley or strait, (2) that it is a grabben, (3) that it is a syncline, or (4) that it is a buried solution valley. The authors prefer the second hypothesis. Further study will be required to assess the nature and origin of the Gulf Trough and its effect on the ground-water flow system. HYDROLOGY Aquifer Systems Definition An aquifer system is herein defined as a body of material of varying permeability that acts as a water-yielding hydrologic unit of regional extent. The con- cept of an aquifer system is desirable because it provides a framework for grouping local aquifers and confining units into a regional hydrologic unit. This study defines the Dublin aquifer system of Paleocene and Late Cretaceous age and the Midville aquifer system of Late Cretaceous age. Each aquifer system was named for a geographic feature near a test well that penetrates strata representative of the geologic and hydrologic properties of the aquifer system. This method of naming allows aquifer systems to cross time and geologic formation lines and is therefore independent of changing stratigraphic nomenclature. Although the aquifer systems defined herein are regional in extent, they contain discontinuous confining layers that locally separate them into two or more aquifers. Such local confining units are not significant in a regional evaluation, but they increase the complexity of the hydrologic framework. The number and thickness of confining units penetrated by wells in the study area were measured from borehole geophysical logs, and descriptions of drill cuttings and core samples. Confining units 20 ft or more thick were considered to be most significant and are shown on cross sections A-A', B-B', C-C', and D-D' (pls. 1 and 2). Three confining units were judged sufficiently thick and widespread to have regional significance, and together with the Coastal Plain floor, define the upper and lower limits of the Dublin and Midville aquifer systems. In the study area, several aquifers and aquifer systems are used for water supply. They are, in descending order: (1) the Jacksonian aquifer (Vincent, 1982), comprised largely of calcareous sand and limestone of the Barnwell Formation (2) the Gordon aquifer system (Brooks and others, 1984), comprised largely of sands of early and middle Eocene age; and (3) the Dublin and Midville aquifer systems of this report. The general correlations of the aquifer units are shown in table l. 15 Dublin aquifer system The Dublin aquifer system was named for sediments penetrated by well 21U4 (pls. 1 and 2; Appendix A) drilled near Dublin, Laurens County. At this well, the upper part of the Dublin aquifer system consists of fine to coarse sand and limestone of the lower Huber-Ellenton unit, whereas the lower part consists of alternating layers of kaolinitic sand and clay of the Peedee-Providence unit (table 1). The Dublin aquifer system is confined above by clayey beds of the Baker Hill-Nanafalia unit and below by clay and fine silt of the upper part of the Black Creek-Cusseta unit. Throughout most of the study area, the Dublin aquifer system is a single hydrologic unit, because clay layers within the system seem to have limited areal extent (pls. 1 and 2). For example, on section A-A', several clay layers are present within the aquifer system at well 21U4, that are absent at wells 18T1 and 24V1. These layers may be local confining units, but do not extend laterally over a large enough area to be considered regionally significant confining units. Exceptions occur in the western and eastern parts of the study area, where widespread clay layers divide the Dublin aquifer system into several discrete aquifer units. In the western part of the study area, the upper part of the Dublin aquifer system grades laterally into the Paleocene Clayton aquifer of Clarke and others (1984); and the lower part grades laterally into the Upper Cretaceous Providence-Cusseta aquifer of Clarke and others (1983). This division is shown at well 18T1 on section A-A 1 (pl. 1) where the upper part of the Peedee-Providence unit grades into silty clay and very clayey sand that forms a confining unit which continues westward and separates the Clayton and Providence-Cusetta aquifers. To the east, near the Savannah River, clays within the upper part of the lower Huber-Ellenton unit form a confining unit that separates an upper aquifer of Paleocene age from a lower aquifer of Late Cretaceous age (wells AL-19 and AL-23, pl. 2). In the eastern part of the area, the confining unit that overlies the Dublin aquifer system is less than 20 ft thick and is not an effective confining unit. In this area, the Dublin aquifer system is hydraulically connected with the overlying Gordon aquifer system (table 1). This hydraulic connection occurs near the Savannah River and is characterized by wells 31Z2 and AL-324 (section D-D 1 , pl. 2). In southern Laurens County and in Treutlen County, the Dublin and Gordon aquifer systems may be connected between wells 23T1 and 25T2 (section B-B', pl. 1). Midville aquifer system The Midville aquifer system was named for sediments penetrated by well 28X1 (pl. 1; Appendix A) near Midville, Burke County. At this well, the upper part of the Midville aquifer system consists of fine to medium sand of the lower part of the Black Creek-Cusseta unit and the lower part of the aquifer system consists of alternating layers of medium to coarse sand, silt, and kaolin of the MiddendorfBlufftown unit (table 1). In the eastern part of the study area, the Hidville aquifer system locally includes as much as 35 ft of sand from the upper part of the Cape Fear unit (wells SRP-P5A and AL324, pl. 2). The Midville aquifer system is confined above by the upper part of the Black Creek-Cusseta unit and its base is marked by semi-indurated to unconsolidated kaolinitic sand of the Cape Fear unit. At wells 20V4, 23T1, and 25T2 (section B-B 1 , pl. 1), the Cape Fear unit which forms the base of the Midville aquifer system contains several layers of poorly consolidated, permeable sand, ranging in thickness from about 20 to 210 ft. In the southern part of the study area, these permeable sand layers make up over 50 percent of the Cape Fear unit (wells 23T1, 25T2, pl. 1) and are prob- 16 ably hydraulically connected with the overlying Midville aquifer system. This hydraulic connection occurs between wells 24U1 and 23T1 on section B-B 1 (pl. 1) and between wells 24V1 and 25T2 on section C-C 1 (pl. 2). Dublin-Midville aquifer system In the northern one-third of the study area, the Black Creek-Cusseta confining unit that separates the Dublin aquifer system from the Midville aquifer system becomes sandier and is, therefore, not an effective confining unit. In this area, the Dublin and Midville aquifer systems combine to form a single aquifer system, herein called the Dublin-Midville aquifer system. Changes in the lithology and confining character of the intervening Black Creek-Cusseta confining unit are illustrated on sections B-B 1 , C-C 1 , and D-D 1 (pls. 1 and 2). For example, along section B-B 1 the confining unit progressively thins to the north, decreasing to a thickness of about 35 ft at well 20V4. North of well 20V4 the confining unit is absent and the two aquifer systems combine to form the Dublin-Midville aquifer system. The approximate northern limit of the Black Creek-Cusseta confining unit is outlined in figure 7. The Dublin-Midville aquifer system is generally confined above by clayey beds of the Baker Hill-Nanafalia unit and below by semi-indurated, kaolinitic sand of the Cape Fear unit (table 1). In the northern part of the study area, the Baker Hill-Nanafalia confining unit is absent and the Dublin-Midville aquifer system is hydraulically connected with the overlying Gordon aquifer system (well 24X5, pl. 1). In the extreme northern part of the study area, the Cape Fear confining unit is absent-and the DublinMidville aquifer system overlies low permeability rocks that are part of the Coastal Plain floor (fig. 8). Altitude of Tops of Aquifer Systems and Confining Units Borehole geophysical and lithologic logs of wells in the study area were used to estimate the altitudes of the tops of: (1) the Dublin and Dublin-Midville aquifer systems (fig. 5); (2) the Midville aquifer system (fig. 6); (3) the Black Creek-Cusseta confining unit (fig. 7); and (4) the base of the Midville and Dublin-Midville aquifer systems (fig. 8). In Bulloch and Screven Counties, it was not possible to measure accurately the altitudes of the top and base of theaquifer systems because of sparse geologic control. In this part of the area, the contours shown in figures 5-8 represent an approximation of the top of a unit. Depths below land surface to the top of a unit may be calculated by subtracting the altitude of the top of the unit (figs. 5-8) from the altitude of land surface shown on u.s. Geological Survey 7. 5-minute topographic quadrangle maps. Thickness and Sand Content Maps showing the approximate thickness, sand content, and number of sand layers having a thickness of 20 ft or more in the Dublin, Midville, and DublinMidville aquifer systems were constructed using data from geophysical and lithologic logs (figs. 9, 10). The number of sand layers 20 ft or more thick is an indication of the number of separate waterbearing intervals available to be screened in a well. The aquifer systems have the greatest potential for development in areas where the thickness, percentage of sand (figs. 9, 10), and the transmissivity (fig. 12) are greatest. Aquifer system thicknesses were computed by comparing maps showing the altitude of the top of each aquifer system with the altitude of the top of the underlying regional confining unit or base of the aquifer system. For example, the thickness of 17 EXPLANATION OUTCROP AREA OF LOWER TERTIARY AND CRETACEOUS SEDIMENTARY ROCKS, UNDIFFERENTIATED D - DUBLIN AQUIFER SYSTEM-Area in which Dublin aquifer system acts as a discrete aquifer system. Contours in this area show top of Dublin aquifer system bl:~;~ ous~;~~~~~~;'/~L; cAo'!~1i~;~ ::u~Je~Ms~~:~~ ~o~t~~~s ~~b:~~sa~~e~i~~~~~e t~~u~r Dublin-Midville aquifer system ~-- FAULT-U, upthrown side; 0, down thrown side; dashed where inferred -a-- STRUCTURE CONTOUR-Shows altitude of top of Dublin and Dublin- Midville aquifer sytems. Dashed where approximately located . Contour interval 100 feet. Datum is sea level 130 DATA POINT-Number is altitude of top of Dublin or Dublin-Midville aquifer system, in feet / .,... ~3 .._ OL .... ~E fj ... .~, a <" " N. "' ' = - 321 ~~ :--~Q "-/ t-~ f-' 00 R -600 ~ E M ~ ,.... .,oa,-- ----~:.,..... ___ - - - - - _...,,_ I 'I r ' I 110 !t' '{J r.. MILCS 32" !l:i.-ifi --P, Qm L.i S.. Gil e ~clfl11~ 5~otrn , 83" 13to:JI& bU!Io ma.!UI t IUlO, OVO 82" Outcrop arco:J lrom Geologic Mop of Georgia, 1976 Figure 5.-Structural features, outcrop area, and altitude of the top of the Dublin and Dub linMidville aquifer systems. ' EXPLANATION - 0 - - STRUCTURE CONTOUR-Shows altitude of top of Midville aquif~r system . Dashed where approximately located. Contour interval 100 feet. Datum is sea level / 8 OAT A POINT-Number is altilude of top of Midville aquifer system, in feet cqL_~r-.,~Eii "N < I' f--1 ~ . \'J :;,rt 7"~'/ < ,_ co~ _.., '"'"(;. - c.~:Y"',. '1'0~0- - = . I '"'' "-/ ~-_:.-------- o\\."-~ e N _...:;..- . - - - - - _ _e. - 'r , /, e'-"c.~ . . A t .. 5!!!o! ~ / / "' El L - - ~ // -~"'/0~// 7"" /, < .,. .': 6 ,<: / / r " / . . -- - -~-~ ..~ -- - . ..... ' . / / , / '// /_,// ' / . . . . - - - - " - . -- --- ~~ ..... - . - / ;;;: ' 000 ... , / / / / / / / __, / /' / / / / / / / / / ' / 0 I ..._ - -- ~ ~ /' 0 /1 -% / , : / , / / ---- / / / . / l, "' - - // . / / // / \ , ,/ / _,-" // , / / 1,. // // '// 32' ~ 10 0".1 l!) ~"''I_..-- -1r' o\lo'~''"V /f I r 9 A. A L ;;u/ / _.(, . ,_ -- '7 - ' ::// / , ,.. ..... ~~---~- /-~~ ----. . '"s~ r '"' / ;;/ ~-:r- .-~~/ ----~ --~., v }v'' i - / ' o.F / _/:::/~-/- ;;/;.-- ? _,..,.- ------ - / / 7-/../0. -,~ ----- _::. ~- ,. ~"'?::,. ~::-=-- .,~ ~--- . " .,o9-1v.~~"~" / ~//./ r / rL// .- "?/).,-/o/''' / Y ,;r ,c"'/..,..,o.<. /"7"&/.:\ ___.- . -- \ - " 1$ C R ~ ,! " -,.V - ~/, ~\.&~ - -;/ _~"/ / .< . ~~--:~----------------- //~ ~- <> ,<> ' <>"' -;-' ;/,,/ ., v -' .. / . -/. . _ //~. ./0.,a/"'.'.~-/~-/ ~...._. _,,oo ------- -- /~-~% ; / / / / / _/ /_ ,. , . $ - /,/ .. _______ _ / / :// ;,//; // /7 / / / .. :.---""'________ ---- / / / / / ..: ,,. _~ ;/'J/// / // / / // / // / / c " 7 / 7: , )._ ~- .- - -..ucc<. '- i'\ / / " - ": -:oc / $ 2 -f ... 0 10 20 JO ~0 Mll:O:S a n h'O n~Q )oo l u ~u r vn 82" QiMa ~ maps, l:liQ U,OOO Figure 7 Altitude of the top of the Black Creek-Cusseta confining unit. EXPLANATION BASE OF COASTAL PLAIN STRATA-Contours in this area show base of Coastal Plain stra !a I I CAPE FEAR CONFINING UNIT- Contours in this area show top of Cape Fear L - - J confining unit -f;-- FAUL T-U, up thrown side; D, downthrown side; dashed wher03 inferred -0-- STRUCTURE CONTOUR-Shows altitude of base of the Midville or Dublin-Midville aquifer system ~ Dashed where approximately located . Contour interval 100 feet. Datum is sea level -so DATA POINT-Number is altitude of top of Cape Fear confining unit, in feet l. T69 DATA POINT-Number is altitude of top of basement rock, in feet 33' t-:1 '""" -6e.ift. ' C. 1\ ~; u :/11 E l L i.: E ....... I) 10 .:'o 30 -to r.11L'-::. 32' 1.. " ' I I I Da1u1 tr(l m. Us. c.eo 4a Q1CIII ! ~ur ,lt )' Slalc base map~ t ~ O Q..Qtl[] 83 ' 82' Figure B.-Structural features and altitude of the base of the Midville and Dublin-Midville aquifer systems. the Midville aquifer system was computed by subtracting the altitude of the Cape Fear confining unit, or base (fig. 8), from the altitude of its top (fig. 6). The Dublin aquifer system ranges in thickness from about 145 ft in western Houston County to about 570 ft in eastern Laurens County (fig. 9). The Midville aquifer system ranges in thickness from about 195 ft in eastern Burke County, to about 645 ft in Dodge County (fig. 10). The Dublin-Midville aquifer system ranges in thickness from about 80 ft in northern Jefferson County, to about 620 ft in western Aiken County, S.C. (figs. 9, 10). Aquifer and Well Properties Specific capacity The specific capacity of a well is defined as yield per unit of drawdown, generally expressed in gallons per minute per foot [(gal/min)/ft]. Values range from 0.7 (gal/min)/ft at well 27AA2 tapping the Dublin-Midville aquifer system in Richmond County, to 69.3 (gal/min)/ft at multiaquifer well 16U20 tapping both the Dublin and Midville aquifer systems in Houston County (Appendix A). Specific-capac.ity data are used to estimate aquifer transmissivity. Transmissivi ty The transmissivity of an aquifer is a measure of the aquifer's ability to transmit water, and generally is expressed in feet squared per day (ft2 /d). Transmissivity values listed in table 2 and Appendix A, and shown in figure 12, are probably somewhat lower than the total aquifer system transmissivity because they have been measured only from the interval of the aquifer system that was screened in a given well. Transmissivities were calculated by analysis of time-drawdown or time-recov- ery data, and by application of a linear regression model to specific-capacity data (table 2; fig. 12; Appendix A). The linear regression model was based on paired specific-capacity and transmissiv~ ity data from 16 wells (table 2) distributed throughout the study area and was used to estimate an approximate relation of transmissivity to specific capacity. The resulting equation is listed below: T = 420 + 554 X sc, (1) where T is the estimated transmissivity in feet squared per day, and SC is the specific capacity in gallons per minute per foot. The correlation coefficient is 0.9. Considering that a correlation coefficient of 1.0 indicates a perfect correspondence between two variables, a value of 0.9 indicates that specific capacity is a reasonable approximation of transmissivity. A comparison of observed transmissivity computed from time-drawdown or time-recovery data with estimated transmissivity computed from equation (1) is shown in figure 11. Transmissivity estimated using equation (1) differed from the transmissivity computed using time-drawdown or time-recovery data by an average of 30 percent, and ranged from 73 percent lower to 78 percent higher. The transmissivity of the Dublin, Midville~ and Dublin-Midville aquifer systems is shown in figure 12. In the northern third of the study area, the Dublin and Midville aquifer systems are combined and the contours on figure 12 are representative of the Dublin-Midville aquifer system. In the southern twothirds of the study area, the Dublin and Midville aquifer systems are separate hy- drologic units, and transmissivity data from wells tapping the Dublin and Midville aquifer systems, and from multiaquifer wells tapping both aquifer systems, are plotted on figure 12. 22 EXPLANATION DUBLIN-MIDVILLE AQUIF ER SYS TEM-Area in which Dublin and Midville aquif er systems from a combined aquifer system. Values in this area are tor the Dublin-Midville aquifer system D . DUBLIN AQUIFER SYSTEM -Area in which Dublin aquifer system form s a discrete aquifer s ystem - ~--F AU L T- U, upthrown side; 0, d own thrown side; dashed whe r e i n terred -200-- LINE OF EQUAL THICKNES S OF THE DUBLIN AQUIF ER SYSTEM-Dashed where approximately located.. Inter va l 100 feet DATA POINT ~ THICKNESS-Number is thickness of Dublin or Dublin-Midville aquifer system, in feet PE:ACEN'T SAN D-Number is the perce ntage of sand in the Dublin or Dubl in-Midville aquife r system rank ed :s f o ll ow~,:/ 1, 0-60; 2, 60 -7 0; 3, 70-80; 4, B0-90; 5, 90 1 00 / ~ NUMBER OF SAND LAYER S 20 FE ET OR MORE THI CK 33' 1:-..J C/..J ~ rrn ~- 1-L;: E -- --- ----- r --- t) tO :.>o 30 <~ \HU:S. 32' 83" 82" Figure 9.-Thickness and percentage of sand in the Dublin and Dublin-Midville aquifer systems. EXPLANATION DUBLIN-MIDVILLE AQ UIFER SYSTEM-Area in which Dublin and Midville aquifer systems form a combined aQuifer system. Values in this area are lor Dublin-Midville aquifer system D - MIDVILLE AQUIFER SYSTEM-Area in which Midville aquifer system forms a discrete aquifN system -7-- FAULT-U, upthrown side; D, downthrown side; dashed where inferred -700-LINE OF EQUAL THICKNESS OF THE MIDVILLE AQUIFER SYSTEM-Dashed where ... approximately located. Interval 100 feet DATA POINT T H ICKNESS-Number is thickness of Mdvillc or Dublin-Mid ville aquifer system, in fee t ' PERCENT SAND -Number is t he percentage of ~and in the Mid~lle _or Dub~n-~idville_ aq~ife r sy_s tem ranke~ as follows: 1, 0 60, 2. 60 70, 3, 70 80, 4, 80 90; 5, 90 100 L ~UMBEFI OF SAND LAYERS 20 FEET OR MORE THICK :-. L :<3" t..v,.. o 'to ~,w ..! o AIO ''lt.C"' 32' 1 & ~u:t~-Ovilo.;lu i thirt.,."..- ::;;u:iw- bHo ~~ 1.D OO,OQG 83" 82" Figure 10.-Thickness and percentage of sand in the Midville and Dublin-Midville aquifer systems. Table 2,--Aquifer properties at wells in which aquifer tests were conducted County Well number Aquifer Open interval (feet) Yield (gal/min) Specific capacity [(gal/min)/ft] Observed transmissivity (ft2/d) Hydraulic conductivity (ft/d) Bibb Burke Houston 16V20 Dublin- Midville 50 31Z8 Dublin, Midville 83 31Z4 do. 85 28X1 Midville 40 31Z2 Dublin, Midville 125 16U11 Midville 70 17U13 do . - 16T2 Dublin, Midville 60 17U8 do . 40 565 -- - 110 1,200 1,300 1,000 1,560 755 9.8 - 2.1 56.4 44.9 33,0 44.5 23.6 4,100 31,000 26,000 7,100 21,000 29,000 20,000 32,000 7,800 80 370 310 180 170 410 - 530 200 Richmond 29BB19 Dublin- Midville 20 -- - 30AA14 do. 60 - - 30AA15 do. 20 - -- 30BB33 do. 25 400 8.1 30AA12 do. 137 505 4.0 29BB3 do. 30 400 8.5 6,900 340 7,600 130 6,600 330 7,900 320 3,400 25 3,200 110 Twiggs 18V7 Dublin- Midville 100 2,060 52.8 37,000 370 17V4 do. 90 1,175 12,1 8,700 100 18V18 do. - (1 ) - 32,000 -- 18V19 do. - ( l) - 34,000 -- 18V20 do. - (l ) - 34,000 - 18V21 do. - ( 1 ) - 32,000 - Washington 22Y29 Dublin- Midville 68 22Y32 do . 70 1,040 835 22.1 19.0 7,300 110 7,200 100 22Y7 do . 30 220 4.0 2,700 90 Wilkinson 19W1 Dublin- Midville 210 ( 1) - 6,800 30 19W4 do. 50 705 7.3 3,300 65 19W2 do. 210 ( l) - 5,100 25 19W3 do. 210 (l) - 3,600 15 1 No yield recorded, observation well for aquifer test. 25 37. 00{] 26,QDD I <1 , 6 tlfl' ~ r, I ' I I I I I b ' '\ ' ' o ~Q~~--L-L-+-J--L-L~~. .~~~--- "~--~~ NUMBER OF OBSERVATIONS Figure 11.---Comparison of observed transmissivity computed from timedrawdown or time-recovery data with estimated transmissivity computed from equation(1). The transmissivity of the Dublin-Midville aquifer system ranges from about 800 ft2/d at well 27AA2 in northern Richmond County, to about 39,000 ft 2 /d at well 16U20 in Houston County, and exceeds 20,000 ft 2/d in Twiggs, Houston, Wilkinson, Washington, Laurens, and Burke Counties (fig. 12; Appendix A). The transmissivity of the Dublin aquifer system ranges from 2,200 ft2/d at well 19Ul in Twiggs County to about 35,000 ft 2/d at ~ell 20U6 in Wilkinson County. A reduction in transmissivity in the Dublin aquifer system between wells 32U19 in Screven County and well 31T11 in Bulloch County (fig. 12; Appendix A) may be due to the effects of the Gulf Trough. (See section on Structure.) The transmissivity of the Midville aquifer system ranges from about 5,000 ft2/d at well 21U4 in Laurens County to about 29,000 .ft2/d at wells 16U4 and 16Ull in Houston County (fig. 12; Appendix A). Hydraulic conductivity Hydraulic conductivity, like transmissivity, is a measure of an aquifer's ability to transmit water, under a hydraulic gradient, and is commonly expressed in feet per day (ft/d). Horizon- tal hydraulic conductivity is estimated by dividing the transmissivity at a well by the footage of the well bore open to the aquifer. At the Wrightsville test well (well 24V1; Appendix A; pl. 1), core samples were collected for laboratory measurement of vertical and horizontal hydraulic conductivity of the confining units within and separating the aquifer systems. The samples were collected from: (1) a clay in the upper part of the Dublin aquifer system (607 .8-608.7 ft), (2) the clayey lower confining unit (1,100.91,101.5 ft), and (3) a clay within the upper part of the Midville aquifer system (1,200.8-1,200.7 ft). The samples were sealed in wax and sent to Core Laboratories, Dallas, Tex. , for permeameter analysis. Results of the analysis are summarized on table 3. Of the three samples, vertical and horizontal conductivity values were largest in the clay from the upper part of the Dublin aquifer system, and were smallest in the clay within the upper part of the Midville aquifer system. Horizontal hydraulic conductivity values ranged from 1.4 x lo-4ft/d to 8.4 x 10-1ft/d. Corresponding vertical hydraulic conductivity values ranged from 8.2 x 10-5ft/d to 2.4 x 10-1ft/d (table 3). Horizontal hydraulic conductivities in the aquifer systems were estimated at 24 wells by dividing the observed transmissivity by the total open interval in the well. Values ranged from 15 ft/d to 530 ft/d (table 2). Horizontal hydraulic conductivity is useful in estimating the transmissivity of the entire saturated thickness of an aquifer. For example, at well 28X1 in Burke County (Appendix A), the transmissivity estimated from aquifer-test data was 7,100 ft2/d and is relative only to the open interval in the well ( 40 ft). On the other hand, the transmi~sivity 26 EXPLANATION DUBLIN-MIDVILLE AQUIFER SYSTEM-Area in which Dublin and Midville aquifer systems form a combined aquiler system D AREA IN WHICH DUBLIN AND MIDVILLE AQUIFER SYSTEMS ARE DIFFERENTIATED -s-LINE OF EQUAL TRANSMISSIVITY. IN THOU SANDS OF FEET SQUARED ' PER DAY-Interval is 5000 feet sq uared per day " DATA POINT-Number is tran s mi ssivi ty, in thousands of feet s quared per day WELL IDENTIFICATION BY AQUIFER SYSTEM Dublin-Midville Midville + f Dublin Dublin and Midville (multiaquifer well) l ~ 331- ( ~ -l 32. 0 10 1.. , , , , 1 _______y__ :.\ O 4 0 MIl : S (~:."t~ ~~::; -~:J14?tQJog:~~.SWtY'f 83' 82' Figure 12.-Estimated transmissivity of the Dublin, Midville, and Dublin-Midville aquifer systems. Table 3.--Hydraulic conductivity of sediments cored at well 24V1, near Wrightsville, Johnson County Interval (ft) Hydrologic unit Lithologic description Hydraulic conductivity1 (ft/d) Horizontal Vertical 607.8608.7 1,100.91,101.5 1,200.01,200.7 Clay within Dublin aquifer system Black CreekCusseta confining unit Clay within Midville aquifer system Micaceous, carbonaceous, silt and clay Micaceous, carbonaceous, clayey silt and very fine sand Micaceous clay and silt 8.4 X 10-1 2 2 X 10-2 1.4 X 10-4 2.4 X 10-1 1.1 X 10-4 8.2 X 10-5 1Values measured by permeameter analysis of core samples. relative to the total saturated thickness of the aquifer system was about 40,000 ft2/d and was estimated by multiplying the horizontal hydraulic conductivity (180 ft/d) by the total saturated thickness (about 220 ft). This value is probably somewhat larger than the actual transmissivity of the aquifer system because: (1) the estimated value does not account for variation in transmissivity within the aquifer system, and (2) it is likely that the screens were put in the most productive zones of the aquifer. Yield Yields exceeding 1,000 gal/min are obtained from wells tapping the Dublin aquifer system in Laurens and Screven Counties; the Midville aquifer system in Houston County; and the Dublin-Midville aquifer system in Twiggs, Washington, Wilkinson, and Jefferson Counties (Appendix A). Multiaquifer wells tapping both the Dublin and the Midville aquifer systems in Houston and Burke Counties also have been reported to yield more than 1,000 gal/min. Ground-Water Levels Seasonal and Long-Term Fluctuations Water-level fluctuations in the Dublin, Midville, and Dublin-Midville aquifer systems are related to seasonal changes in precipitation, evapotranspiration, and pumping rates. A network of seven water-level monitoring wells was established during 1975-83 to monitor seasonal fluctuations and long-term trends (fig. 22; Appendix A). The wells are near Midville in Burke County (well 28X1), near Wrightsville in Johnson County (well 24V1), near Dublin in Laurens County (well 21U4), near McBean in Richmond County (well 30AA4), near Adams Park in Twiggs County (well 18U1), near Gordon in Wilkinson County (well 19W4), and in northern Pulaski County (well 18T1). Although there are no exact data to indicate the extent of water-level fluctuations where the Dublin-Midville aquifer system is unconfined in its outcrop area, annual water-level fluctuations probably range from 1 to 15 ft, depending on the location and the amount of precip- 28 itation. For example, the water level in well 30AA4, tapping the Dublin-Midville aquifer system where it is semiconfined, about 4 mi south of the outcrop area at McBean, Richmond County, fluctuated about 1.3 ft in 1980 and 0.8 ft in 1981 (fig. 13). A comparison of the water level in this well with the cumulative departure of precipitation at National Weather Service station 090495 (Augusta WSO AP (R) GA) near Augusta, Richmond County (fig. 13), indicates that the water level is influenced primarily by seasonal changes in precipitation. From June 1979 to April 1981, mean monthly water levels in the well declined 0.5 ft, corresponding to a period of lower-than-normal precipitation. Small rises in the water level during this period probably reflected changes in local pumping. Water-level fluctuations in the nearby outcrop area of the Jacksonian aquifer (Vincent, 1982) probably reflect water-table conditions and correspond to those that would be expected in wells located in the outcrop area of the Dublin-Midville aquifer system. For example, the average annual water-level fluctuations at well 21T1 north of Dexter, Laurens County (location shown in fig. 3), ranged from about 6 to 13 ft during 1973-82 (fig. 14). Mean monthly water levels in the Dublin aquifer system at well 18U1 near Adams Park in Twiggs County showed annual fluctuations ranging from about 0.9 to 1.8 ft during 1975-82 (fig. 15). Although the well is about 3 miles from the outcrop area, water levels in the well are probably affected both by seasonal changes in precipitation and by changes in pumping rates in the Huber-Warner Robins area, about 9 mi north of the well, where pumpage exceeded 30 Mgal/d during 1980. A comparison of mean monthly water levels in well 18U1 with the cumulative departure of precipitation at National Weather Service station 095443 (Macon WSO AP (R) GA) near Avondale in southern Bibb County (fig. 15) shows that prior to March 1977, water levels in the well seemed to show a greater response to precipitation. This is suggested by a water-level rise of 1.8 ft from March 1976 to March 1977 that generally corresponded 114 r -- - - --,-- - - - - - - - , - -- --------, 40 w 0 <( LL 1 16 0: ::> (/) 0z 1 17 <( _j (/) w 30 I 0 z 20 ~ _j ~ 1Z t w _j ffi 122 f<( 5: 123 / Waler level 124 L __ _ _ _-----l._ _ __ _ 1979 1960 _j__ __ _ 196 1 _ J . QQ Figure 13.-Mean monthly water levels in the Dublin-Midville aquifer system at well 30AA4, and the cumulative departure of precipitation at National Weather Service station 090495, Richmond County, 1979-81. 25 fw-Wo W: g;"-"- ~ 30 _(/) ujo >z ~:3 35 aw:?o; f-...J ~~ 40 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 Figure 14.-Mean monthly water levels in the Jacksonian aquifer at well 21T 1, Laurens County, 1973-82. Modified from Stiles and Mathews (1983). to a period of greater-than-normal precipitation (fig. 15). After March 1977, the water level in the well was probably influenced more by changes in pumping rates than by precipitation. This is suggested by a water-level decline of about 1. 7 ft from March 1977 to March 29 w (.) ~ 162 a: :e:n> 163 <0z 164 --' ~ ! 66 - Mean monthly water level -w-' CD 166 .... 138 w w u. 130 B z I I I Dashed where no mcord avollabla - _j 140 w >w 14i --' a: . (/) a z <( ...J ;:: 0 5I ...J UJ CD .... UJ UuJ. ~ ~2 _j UJ > UJ ...J a: .U..J. 53 <( ;;: 54 1980 1981 1982 1983 1984 Figure 16.-Mean monthly water levels in the Midville aquifer system at well 28X1, Burke County, 1980-84. 1982, a period of generally greater-~han normal precipitation and increased pumping in the Huber-Warner Robins area; and by a water-level rise of about 1.4 ft from November 1981 to December 1982, a period of lower-than-normal precipitation and reduced pumping in the Huber-Warner Robins area. Well 18U2 is about 1,000 ft northeast of well 18U1 and taps the Midville aquifer system (see location, fig. 3). Periodic water-level measurements in well 18U2 from June 1976 to October 1982 indicate a decline in water level of about 7 ft and a seasonal response to pumping similar to that in well 18U1 (fig. 15). The larger decline in well 18U2 is probably due to greater pumping from the Midville aquifer system than from the Dublin aquifer system in the Huber-Warner Robins area (table 4). UJ (.) <( au:. ::> (/) 0 z <( ...J 13 0 ;:: 0 .w..J CD >ww- "- ~ 13 1 w...J > UJ ...J a: .U..J. <( ;:: 1980 1981 1982 1983 1984 Figure 17.-Mean monthly water levels in the Midville aquifer s y s t e m a t w e II 2 4v-1-, - J o h n s o n County, 1980-84. 30 This is because the aquifer system is deeply buried and is not affected by local precipitation, and the outcrop area is too far away for varying rates of recharge to have a pronounced effect on the water level. Well 24V1 is about 13 mi south of the outcrop area and well 28X1 is about 18 mi south (fig. 3). In addition, there is little, if any, local pumping from the Midville aquifer system in these areas. (See section on Water Use.) Most of the pumping is to the north where the Dublin and Midville aquifer systems combine to form the DublinMidville aquifer system. Mean monthly water levels in well 28Xl rleclined 4.6 ft from June 1980 to January 1984 (fig. 16). Similarly, mean monthly water levels in well 24V1 declined 2.1 ft from November 1980 to November 1983 (fig. 17). These declines probably reflect increased regional pumping. Potentiometric Surface The potentiometric surface of an aquifer is an imaginary surface representing the altitude to which water would rise in tightly cased wells that penetrate the aquifer (Lohman, 1972). The potentiometric surfaces of Dublin, Midville, and Dublin-Midville aquifer systems were contoured primarily from well data. Within and near the outcrop area, potentiometric contours cross rivers and streams where the altitude of the stream surface was considered to be nearly coincident with the altitude of the potentiometric surface. Although there are few data to indicate the extent of water-level fluctuations in the outcrop area, annual waterlevel fluctuations probably range from 1 to 15 ft, depending on the location and the amount of precipitation. (See section on Seasonal and Long-Term Fluctuations.) Consequently, natural water-level fluctuations in the outcrop area of the Dublin-Midville aquifer system _are probably too small to alter the configuration of the potentiometric surface at the contour interval used in figures 18 and 19. The potentiometric maps on figures 18 and 19 show the principal direction of ground-water flow and areas of recharge and discharge. Four major discharge areas--the Ocmulgee River to the west, the Savannah River to the east, and the Oconee and Ogeechee Rivers in between--are drains to the regional ground-water-flow system. Ground-water discharge to these rivers is indicated by potentiometric contours that bend upstream in an inverted "V" pattern showing that the hydraulic gradient is toward the stream. The potentiometric contours also show two major ground-water divides--one to the southwest between the Ocmulgee and Oconee Rivers, and the other to the southeast between the Oconee and Savannah Rivers. There also are a large number of small ground-water divides in the outcrop area that generally correspond to interstream drainage divides. Significant quantities of precipitation recharge the aquifer near divides in the outcrop area. In the southern two-thirds of the study area, the Dublin and Midville aquifer systems are separate hydrologic units. However, owing to a scarcity of data in this part of the area, figures 18 and 19 show data from both the Dublin and Midville aquifer systems. In a few parts of the study area, there are sufficient water-level data to define potentiometric differentials between several aquifer systems (fig. 20). Water-level measurements indicate that: (1) the potentiometric surface of the Midville aquifer system was about 20 ft higher than the potentiometric surface of the Dublin aquifer system in central Twiggs County in September 1981, and about 2 ft higher near Dublin, Laurens County, in January 1982; and (2) the potentiometric surface of the Midville aquifer system was about 12 ft higher than the potentiometric surface of the Gordon aquifer system (table 1) near Midville, Burke County, during May-June 1980. In a multiaquifer well, the water level is a composite of the head of each of the aquifers tapped by the well. For example, near Dublin in Laurens County, well 21U2 (Appendix A) taps the Jacksonian aquifer, the Gordon aquifer system, 31 -D EXPLANATION DUBLIN-MIDVILLE AQUIFER SYSTEM-Area in which Dublin and Midville aquifer systems form a combined aquifer s ystem D AREA IN W~I CH. DUBLIN AND MIDVILLE. AQUIFER SYSTEMS ARE DIFFERENTIATEDContours '" tht s a rea are for the Oubhn aquifer system - 200-- POT EN TIOMETRI C CONTOUR-Shows altitude at which water would have sto od in tightly cased we lls . Dashed w h ere approximately locate d . Conto ur interval 5 0 feet. Datum is s ea level WELL IDENTIFIC ATION BY AQUIFER Dublin aquifer sy st em + Midville aquifer sys tem + Dublin and Midville aqu ife r systems (multiaqulfer well) ' Dublin-Midville aquifer system --...; 33" C;,j !:>:I I j l' " / ,...._,./, I' :8:# -160- WATER-LEVEL CONTOUR-Shows altitude at which water would have stood in tightly cased wells. Dashed where approximately located. Contour interval 10 feet. Datum is sea level - s o - LINE OF EQUAL DRAWDOWN-Dashed where approximately located. Interval 10 feet 0 1b P,UMPING W ATER (c LEVEL ------~.-..DIRECTION OF GROUND-WATER FLOW 18V2(170) e DEWATERING WELL-Number inside parentheses is altitude of water surface in feet; number outside parentheses is well identification 18V9(84) -.... DEWATERING WELL-Number inside parentheses is drawdown in feet; number outside parentheses is weii identification 83 29' Base from U S. Geological Survey Marion 1:24,000, 1973 83 28' 0 1000 2000 3000 4000 5000 FEET ~~-LLL----~--~-----L--~ Figure 21.-Huber Corporation mine dewatering operation and its effect on ground-water flow, central Twiggs County, 1968-72. 37 EXPLANATION WATER -LEV E"L OECLINE. IN F&T- Estl m iQtad tt~ ca mputfrr.g :decUN! -w h;ure r:ont1:nu& fr tun \ bo 19_44 - fiCJ snd i"~-aG _p1J"!e n tlom~ tJfe surrae01 r"t a r::ra:d - Mora t l'!el'\ -5 0 . 0 2 5""' 00 1.!51~ t WELL AND I_O.ENo'n FtCAT! ON NUMBER---fllumbe.r o.n to:~ fa wahtt"ri!IIVt!l doc lino , In f~ ~t. J-tl NunitJiiU!i ;o.n bHf0111 ll'lo w "cr-IGc! c J ~ .a.t'E!r-lell11 d:no llne - a r t - 1CJal) ~~~~ WA1 rn-LE\IEL M'ONI TOR WELL. IoND t0NTIFIC'-T 10ff NUMBER-E.q,u.lpr;u::d 'IWhh 1CIU1 w-.patJiluoU.!S wraror ""-'e ~te l r.Eaorder WEL.L IO ENTIF.ICATlON EPt AOUJf!::R Dubl in BQ \3iret ,a~y~rm Mld"-'tiiG ~QLITi i!r sy1>.tern Cl.lb lirt.- MTd,. III G AQ'UIU11r t:i~1om + Ou~H n and MidYl lle a-q1.1 H'er :ayt ! Drnl (rnuJrlilqulfer Well) 11Y'OfiOGRr\FJH.-sl'lc w..a; w alele "'t~ tt'tlni:l ~fw ., = !:: gu ~~; 16V18 n~1 tl~ tm !D 3;1" ..,. "':) '-...!::.:: ~ ..r-. :~ ~ ~u t 1 r~ '11" \. . - 29aS-f2 ' :-:... ~- ' / .- < .n ~~~ -1 "' ,.. --'----= I;: t<;~t ill jj:;I,:;,,--;;.,t,,.,- J S0AA2 "..... . ' tvn ua - ;. :30.AA4~a... .... '\.... J , B -~A ~ r~ ~~~ E ( .9 " 20W86 11!1 .11 12 1 511 -l Q ,~ t~8>t1 2c vot3"9- "0"0 ,., . ""~' ;:. 't t:: 18Vl'. ... - " I r.' .__ -=., .fJU - 1H ~l '1/10.-aJ BQ_ 17.;5lllilt71QI 80 ~. u (/) .Q._) .._ Q) "0 '+- ::J Q) .c cr ....... (1j "0 Q) c (1j > "0 Q) .O._l ~ (1j c .c u .0 (/) :J "0 0 uu c c (1j (1j Q) Q) Ol s 0 _j lL 0: w ~ s-< w z 0 N 0 ' z ::::J 0 z 0 C) (f) 0 z w z 0 z z 0: C) _j lL 1<( z <( _J 0: w lL ::::J a -< -< (f) _j w z z -< I u N C) z z lzL 0 u lL z 0 u >- 0 z -< (f) (f) z w _j >-< _j u w w > _j 0: w f- s-< 0 z 0 f- u w 0- : 0 ()_ 01 X w I)'( ~ ' GQJ 40 c '+- 0 .0 E ::J .(.1_j 0 Ol c (1j 0 "0 "..0_ u 0 (.') (1j Q) E .c Q) ....... .c u c (f) I ~ 0 (Y) C\J .._ .Q._) Q) ....... ::J (1j Ol ~ LL EXPLANATION OUTCRO~ AREA OF LOWER T ERT I...RY A ND CRET.. C~OUS SEDIM E NTARY HOCKS, UNOI FfERENT io\'te-O - 0 . 3-- LI NE OF EOUft l GAOUNO-WAT!:A OISCH ~RG E TO STREAJAS--De.s hell whe r-t iiOPfO);Ima.tely - lacate.O. tn.terval 0 . 1 c ub to foo t pot ~eeond Pet" a.qua r o mil e ot d!ra.ln.age ar-.fl-a (0.22)TKu A DATA P O INT-Number lncldo paren tl'uues It gr.;;~ un.d-water dlaei'IDtQG 10 Jttear.nc tn eublo tool p-ot second p.ec .11qmsre milo or Cl(31nago .R.ro iL Leile.rs IDd rcate --~ '- QII!!Oioglc lor111111!on al moo-su rhHil ::it:a fion u foltow.~; ;. TKu-L..owar T.erthu)' - Orelllceout. u n.Qitf.era~tJ st el:l PI)--P oal - Pat~eono unU!i ' .( E N / . B'"' ,,~ N El L 33. / .H..:.::.-. \ \ ,_ ;< --- ., ~ 4 "' ..., \ "'-...,_0 (D.DGIo I {O.O!_JPJ:l ,....X.,O)Po "-,.-- ..... E II N U I. \.. \. -=-~ ~ -0--....:!-~ A U R ' ( = \ -~ \ ::l !:I ::n:: " \....'. t': f \,, 32' .... ~ 'i I 1 :~ '{' "F MILES ,. . . IJVT"l v:iF- ei-.Ol"OG\~irBiJivn State ".._. maps, 1 5-001000 83' 82' Oulcro p ar ea lr om G(I~OOI~ Ma p ol Geo rgia , 1976 Figure 24.-Estimated ground-water discharge to streams from aquifers in eastcentral Georgia, October-November 1954. Table 4.--Estimated water use from the Dublin, Midville, ?nd Dublin-Midville aquifer systems, 1980 [<, less than] Dublin aquifer system Ground-water use (Xgal/d) Midville aquifer system Dublin-Midville aquifer system :::;, ~ ~ rl "'~ :l w rl :l u rl ~ County ..O.:J) rl "0' . .-< u rl >:: ;::;:l: rl "'rl ~ w -":ol' >:: H rl "'~ :l w rl :u l rl Count2 totalV ~ ..b.C: rl .--< "0' . rl "'.-< ~ w u {/) rl >:: -:ol ;::;:l: " H rl "~ ' :l w rl :l u ri Count2 totalV ~ ..b.C: rl "0' . .-< u rl >:: ;::;:l: .--< "'ri ~ w {/) -:ol >:: Count2 Grand H totalV total.V Bibb -- - -- - -- -- -- - - -- 3. l 3. l 3. 1 Burke 0.1 0.3 0.1 0.5 -- -- 0. 1 0. 1 - - -- -- 6 Emanuel -- -- -- - -- -- -- -- -- - -- -- - Houston . 4 3.4 1.4 5.2 0.3 8.4 2.3 11.0 -- 1.6 -- 1.6 17.8 Jefferson -- -- -- -- -- -- -- -- 0.3 <.1 . 7 1.0 1.0 Johnson . l . 1 -- . 2 -- -- -- -- -- -- -- -- . 2 Jones - -- - -- -- - -- -- - .3 -- . 3 .3 Laurens 3 . 7 . 5 1.5 - - - -- - -- -- -- 1.5 Pulaski - I .3 . 7 1.0 -- -- -- - - -- - - -- 1.0 Richmond -- -- - - -- - -- -- -- 10.7 9.2 19.9 19.9 Screven - -- .6 . 6 - - - -- -- -- -- -- - 6 Twiggs . 2 .1 -- . 3 -- - -- - -- .1 38.2 38.3 38.6 Washington - -- -- -- -- - -- -- 2 . 2 lO. 7 11. l 11. l Wilkinson -- <.1 <. 1 <. 1 -- -- -- -- -- 1.5 23.9 25.4 25.4 TotalsV 1.1 4.9 3.3 9.3 0.3 8.4 2.4 11. 1 0.5 14.4 ' - - - - -"--- - -'---- - 1/ ValuEs are estimated growing-season withdrawals averaged over a 365-day period. "'Jj Totals do not include domestic use. 85.8 100.7 121. 1 42 5 0 . - - - - - - - - - - - - - - - - - - - - -- - - - - - - - - - - - - - - , (f) 45 - z 0 f- 40 - LL 0 ~ 35- 0 _.J _.J 30 - ~ ~ 25 - z 0 f- 20 () ::::l 0 0 15 a: CL z _.J 0 <( ~ 5 <1900 1-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 YEAR Figure 25.-Georgia kaolin production, 1900-1980. Modified from Stockman and Pickering (1977). type of construction and the lithologic and geophysical properties of aquifer sediments are typified by well 16Ul at Warner Robins, Houston County (fig. 26; Appendix A). In some areas, the individual aquifer systems supply insufficient quantities of water and are used together or in combination with other aquifers. Multiaquifer wells in Warner Robins, Houston County (well 16U1, fig. 26; Appendix A), and in Burke County (wells 31Z1, 31Z3, 31Z4, and 31Z8, Appendix A) tap both the Dublin and Midville aquifer systems. In Jefferson County, multiaquifer wells (wells 26AA1, 26Y7, and 26Y8, Appendix A) tap both the Dublin-Midville aquifer system and the overlying Gordon aquifer system (table 1). WATER QUALITY Water from the Dublin, Midville, and Dublin-Midville aquifer systems is generally of good chemical quality. With the exception of high concentrations of iron in the central part of the study area, constituent concentrations are within Georgia Environmental Protection Division (1977) standards and recommended limits for drinking water (Appendix B). Water-quality analyses indicate that concentrations of dissolved solids and most other constituents generally increase from the outcrop area southward (fig. 27; Appendix B). Values of pH are generally lower near the outcrop area and range from a low of 3.7 at well 20W44 in Wilkinson County to a high of 8.6 at well 13T11 in Bulloch County (fig. 28; Appendix B). The low values of pH in the northern part of the study area are probably the result of reactions involving the oxidation of a sulfur species or ferrous iron (Hem, 1970, p. 93-95). The presence of iron in drinking water is objectionable because of its taste, staining capacity, and encrusting property. The Georgia Environmental Protection Division (1977) recommends a concentration limit of 300 ~g/L of iron in drinking water. Concentrations of dissolved iron range from less than 300 ~g/L near the outcrop area and in the southern part of the study area, to more than 6,700 ~g/L at well 23U3 in Laurens County in the central part of the study area (fig. 28). Iron in ground water may be derived from decaying organic debris or from iron-bearing minerals, such as pyrite, in the aquifer sediments. The iron in these materials is dissolved as it comes in contact with oxygenated ground water, producing soluble ferrous iron and sulfate (Hem, 1970, p. 124). Near the outcrop area where concentrations of dissolved oxygen are high, iron concentrations generally are less than 300 ~g/1. This comparatively low concentration is 43 w 0 <( 0 lL a: :J (/) 1 00 0 z <( _J 5 200 0 _J w en 300 f- w w lL -z 400 - I f- Q_ 500 w 0 z 0 i= GEOPHYSICAL WELL LOGS 0 ::::) 0: f- >- (9 0 <( ::2' (/) (f) _( z 0 0 0 I f- _( _( _( 2 <( (') :J _J 0 w z <( - f- <( z f- w z f- >- -f- > f- (/) w 0 0 (/) $: Q_ Q_ w (/) a: -------- HYDROLOGIC UNIT GORDON AQUIFER SYSTEM CONFINING UNIT DUBLIN AQUIFER SYSTEM CONFINING UNIT MIDVILLE AQUIFER SYSTEM EXPLANATION U/.:) ~:~::! s AN D B eLAY ETI2] SANDY CLAY GRAVEL ~....!{....;""'""' I I SCREEN ~CEMENT Figure 26.-Well construction and lithologic and geophysical properties of aquifer sediments at well 16U1, near Warner Robins, Houston County. 44 -D EXPLANATION DUBLIN-MIDVILLE AQUIFER SYSTEM-Area in which Dublin and Midville aquifer systems fo r m a combined aQuifer system AREA IN WHICH DUBLIN AND MIDVILLE AQUIFER SYSTEMS ARE DIFFERENTIATEDContours in this area are for the Dublin aQuifer system - S O- - LINE OF EQUAL DISSOLVED-SOLIDS CONCENTRATION-Dashed where approximately loca ted. Inter va l 50 milligrams per liter + 28X1{83E) DATA POINT-Number outside parentheses is well identification; number inside parentheses is dissolved- solids concentration in milligrams per !iter; E, estimated tram sum of co ns tituents /'-c- WELL IDENTIFICATION BY AQUIFER Dublin aquife r system Midville aQuifer system Dublin-Midville aquifer system / ~, L :;; 3 ..,.. c.n i' IU 1(&3El + ~\\ \ ~ -- 1.. :;,. nMC tol \ ulno:r.J \ \ '0 "< .,, \ 6nlfiO) .............. ""'......._ ,D().___ - - - - - ' - ' fti.I I TC1~'H --31T1 1(121) t '' T 210 310 4j MJL :S 32" trom u;to: Go lo.;:lcal aurTIIIl' 82" S tal e b.1::o m.Jp::. 1. 500,000 Figure 27.-Dissolved-solids concentration of water from the Dublin, Midville, and Dublin-Midville aquifer systems, 1940-82. EXPLANATION - DUB Ll N-M iO VILLE AQUIFER SYSTEM-Area In wh i ch the Oub tfn and Mt dv i11 e aqu, fer systems form a combined aquifer system D AREA IN WHICH DUBLIN AND MIDVILLE AQUIFER SYSTEMS ARE DIFFERENTIATED- Contours In this area are for the Dublin aquifer system IRON CONCENTRATION, IN MICROGRAMS PER LITER r---1 Greater than 300-Concentrations greater than 300 micrograms per liter L____J can cause staining of clothing, utensils, and fixtures ~ Less tha.rt "3 00-No treatment r e qu ired lor mo at U~us -7.0-- LINE OF EQUAL pH- Interva l 1.0 uofL Da s hed where approx imate ly located 18V7 DAiA PO lNT-Number Js Well ' dentlfjc a tl on ,J!!!.- rto..n oone e n:t ratl on, In microlram.t ~e r tr t a: e. - I)H, Jn unit&: W ELL IOENTIFICA T I ON BY A.OUIFER Cubltn a Quifo.r ayorm Mldwllle aquUer J.Yitl/1'11 Dublin-;Midvllle aquifer system :n ..,. 0':> K IE El " - wE. L L / 0 10 20 30 ~0 MIL ::::S 32' aue ffcun 0 :i. Co logt ~l S ur~e y Gttttv t:111:a mQOil. t .!00,000 83' 82' Figure 28.-lron concentration and pH of water from the Dub I in, Mid ville, and Dublin-Midville aquifer systems, 1952-82. due to a short period of contact between the oxygenated ground water and the source material. As the ground water moves downdip, more iron goes into solution as the dissolved-oxygen supply is gradually depleted. As a result, iron concentrations in the central part of the study area exceed the 300 ~g/L recommended limit for drinking water. Farther downdip ferrous iron may combine with a reduced sulfur species and precipitate to form a ferrous sulfate, such as pyrite (Jackson and Patterson, 1982), or ferrous iron may combine with colloidal ferric hydroxide and coprecipitate (Langmuir, 1969). These reactions, together with cation exchange, decrease the concentration of iron to less than 300 lJ g/L in the southern part of the study area (fig. 28). SUMMARY In east-central Georgia, interlayered sand and clay of Paleocene and Late Cretaceous age form the Dublin and Midville aquifer systems. In the northern third of the study area, the systems combine to form the Dublin-Midville aquifer system. The aquifer systems have thicknesses that range from 80 to 645 ft and include discontinuous clay layers that result in local zones of confinement. Estimated hydraulic conductivities of aquifer sediments range from 15 to 530 ft/d. The aquifer systems have transmissivities that range from about 800 to 39,000 ft2/d, and wells yield as much as 3,400 gal/min. Water from the aquifer systems is of good quality except in the central rart of the study area, where iron concentrations are as high as 6,700 ~g/L and exceed the recommended limit of 300 ~ g/L for drinking water. During 1980, the aquifer systems supplied an estimated 121 Mgal/d, about .60 percent of which was withdrawn for kaolin mining and processing. Water levels in the aquifer systems have shown little change since 1950 in the southern two- thirds of the study area, but localized declines of as much as 50 ft have occurred due to pumping near industrial, municipal, and kaolin mining and processing centers in the northern third of the study area. Recharge of the aquifer systems by precipitation occurs within and adjacent to the outcrop areas of aquifer sediments, and where ancient stream channels eroded through the overlying confining zone and were filled with permeable sand. Ground-water discharge occurs largely to streams in the outcrop area. Within the southern half of the study area, aquifer discharge occurs through leakage into overlying units. SELECTED REFERENCES Applin, E. R., 1955, A biofacies of Woodbine age in the southeastern Gulf Coast region: U.S. Geological Survey Professional Paper 264-I, p. 187-197. Applin, P. L., and Applin, E. R., 1967, The Gulf Series in the subsurface in northern Florida and southern Georgia: U.S. Geological Survey Professional Paper 524-G, 34 p. Bechtel Corporation, 1982, Studies of postulated Millett Fault: Unpublished report on file at U.S. Geological Survey, Doraville, Georgia, variously paged. Brooks, Rebekah, Clarke, J. S., and Faye, R. E., 1985, Hydrogeology of the Gordon aquifer system of east-central Georgia: Georgia Geologic Survey Information Circular 75. Buie, B. F., Hetrick, J. H., Patterson, S. H., and Neeley, C. L., 1979, Geology and industrial mineral resources of the Macon-Gordon kaolin district, Georgia: U.S. Geological Survey OpenFile Report 79-526, 2 sheets, scale 1:62,500. 47 Chowns, T. M., and Williams, C. T., 1983, Pre-Cretaceous rocks beneath the Georgia Coastal Plain--Regional implications, in Gohn, G. S., ed., Studies related~o the Charleston, South Carolina earthquake of 1886--Tectonics and seismisity: U.S. Geological Survey Professional Paper 1313-L, p. L1-L42. Clarke, J. s., Faye, R. E., and Brooks, Rebekah, 1983, Hydrogeology of the Providence aquifer of southwest Georgia: Georgia Geologic Survey Hydrologic Atlas 11, 5 sheets. 1984, Hydrogeology of the Clayton ----aq-uifer of southwest Georgia: Georgia Geologic Survey Hydrologic Atlas 13, 6 sheets. Eargle, D. H., 1955, Stratigraphy of the outcropping Cretaceous rocks of Georgia: U.S. Geological Survey Bulletin 1014, 101 P Faye, R. E., and Prowell, D. C., 1982, Some effects of Late Cretaceous and Cenozoic faulting on the geology and hydrology of the Coastal Plain near the Savannah River, Georgia and South Carolina: U.S. Geological Survey Open-File Report 82-156, 73 P Ferris, J. G., Knowles, R. H., Brown, R. H., and Stallman, R. w., 1962, Theory of aquifer tests: U.S. Geelogical Survey Water-Supply Paper 1536-E, 173 P Georgia Environmental Protection Division, 1977, Rules for safe drinking water: Chapter 391-3-5, 57 p. Georgia Geologic Survey, 1980, Hydrogeological investigation of the Gordon Service Company Hazardous Waste Facility in Wilkinson County, Georgia, variously paged. Georgia Geological Survey, 1976, Geologic map of Georgia: Atlanta, Georgia, 1:500,000. Gibson, T. G., 1982, New stratigraphic unit in the Wilcox Group (upper Paleocene-lower Eocene) in Alabama and Georgia: U.S. Geological Survey Bulletin 1529H, p. H23-H32. Gohn, G. S., Higgins, B. B., Smith, c. c., and Owens, J. P., 1977, Litho- stratigraphy of the deep corehole (Clubhouse Crossroads corehole 1) near Charleston, South Carolina, in Rankin, D. w., ed., Studies related to the Charleston, South Carolina earthquake of 1886--a preliminary report: U.S. Geological Survey Professional Paper 1028-E, p. E59-E70. Hazel, J. E., 1969, Cytheresis eaglefordensis Alexander, 1929--A guide fossil for deposits of latest Cenomanian age in the Western Interior and Gulf Coast regions of the United States: U.S. Geological Survey Professional Paper 650-D, P D155-D158. Hazel, J. E., Bybell, L. M., Christopher, R. A., and others, 1977, Biostratigraphy of the deep corehole (Clubhouse Crossroads corehole 1) near Charleston, South Carolina, earthquake of 1886--a preliminary report, in Rankin, D. w., ed., Studies related to the Charleston, South Carolina earthquake of 1886--a preliminary report: U.S. Geological Survey Professional Paper 1028-F, P F71-F89. Hem, J. D., 1970, Study and interpretation of the chemical characteristics of natural water: U.S. Geological Survey Water-Supply Paper 1473, 363 P Herrick, S. M., 1961, Well logs of the Coastal Plain of Georgia: Georgia Geological Survey Bulletin 70, 462 P Herrick, S. M., and Counts, H. B., 1968, Late Tertiary stratigraphy of eastern Georgia: Georgia Geological Survey Guidebook for Third Annual Field Trip, 88 P 48 Herrick, S. M., and Vorhis, R. C., 1963, Subsurface geology of the Georgia Coastal Plain: Georgia Geological Survey Information Circular 25, 80 P Hetrick, J. H., and Friddell, M. S., 1983, A geologic study of the central Georgia kaolin district, parts I, II, and III: Georgia Geologic Survey Open-File Report 83-1, variously paged. Huddlestun, P. F., Marsalis, w. E., Pick- ering, S. M., Jr., 1974, Tertiary stratigraphy of the central Georgia Coastal Plain: Geological Society of America Guidebook 12, 35 P Jackson, R. E., and Patterson, R. J , 1982, Interpretation of pH and Eh trends in a fluvial-sand aquifer system: Water Resources Research, v. 18, no. 4, p. 1255-1268. Kesler, T. L., 1963, Environment and origin of the Cretaceous kaolin deposits of Georgia and South Carolina: Georgia Geological Survey Mineral Newsletter, v. 16, nos. 1 and 2, 11 P LaMoreaux, P. E., 1946, Geology and ground-water resources of east-central Georgia: Georgia Geological Survey Bulletin 52, 173 p. LaMoreaux and Associates, Inc., 1969, Plan for dewatering the kaolin clay deposit at the Chambers Mine, Wilkinson County, Georgia: Unpublish~d report on file at U.S. Geological Survey, Doraville, Georgia, 26 p. - -l-in19d80is, tHriycdtr:ologUynpoufbltihsheedGeorergpioartk aoon file at U.S. Geological Survey, Dora- ville, Georgia, 139 p. Langmuir, Donald, 1969, Iron in ground waters of the Magothy and Raritan Formations in Camden and Burlington Counties, New Jersey: New Jersey Department of Conservation and Economic Development Water Resources Circular 19, 49 p. LeGrand, H. E., 1962, Geology and groundwater resources of the Macon area, Georgia: Georgia Geological Survey Bulletin 72, 68 P LeGrand, H. E., and Furcron, A. S., 1956, Geology and ground-water resources of central-east Georgia: Georgia Geological Survey Bulletin 64, 174 P Lohman, s. W., 1972, Ground-water hydrau- lics: U.S. Geological Survey Professional Paper 708, 70 p. Mayer, J. c., and Applin, E. R., 1971, Stratigraphy, in Mayer, J. C., Geologic framework and petroleum potential of the Atlantic Coastal Plain and Continental Shelf: U.S. Geological Survey Professional Paper 659, P 26-65. Miller, J. A., 1982, Geology and configuration of the top of the Tertiary limestone aquifer system, Southeastern United States: U.S. Geological Survey Open-File Report 81-1178, 1 sheet. Owens, J. P., and Gohn, G. S., 1985, Depositional history of the Cretaceous Series in the United States Coastal Plain: stratigraphy, paleoenvironments, and basin evolution: Symposium on the stratigraphy and depositional history of the Atlantic Continental Margin, [in press]. Oxford, E. F., 1968, Development of a kaolin body under hydrostatic pressure: Society of Mining Engineers of America Institute of Mining Engineers, 68-AG-358, 19 p. Patterson, S. H., and Herrick, S. M., 1971, Chattahoochee anticline, Apalachicola embayment, Gulf Trough, and related structural features, southwestern Georgia: Georgia Geological Survey Information Circular 41, 16 P Pickering, S. M., Jr., 1971, Lithostratigraphy and biostratigraphy of the north-central Georgia Coastal Plain: Georgia Geological Survey Fieldtr~p Guide, 1971, 15 P 49 Pollard, L. D., and Vorhis, R. C., 1980, Geohydrology of the Cretaceous aquifer system in Georgia: Georgia Geologic Survey Hydrologic Atlas 3, 5 sheets. Prowell, D. C., and O'Connor, B. J., 1978, Belair fault zone: Evidence of Tertiary fault displacement in eastern Georgia: Geology, v. 6, p. 681-684. Prowell, D. C., Christopher, R. A., Edwards, L. E., Bybell, L. M., and Gill, H. E., 1985, Geologic section of the updip Coastal Plain of central Georgia to western South Carolina: U.S. Geological Survey Miscellaneous Field Series Map MF 1737 [in press]. Reineck, H. E., and Singh, I. B., 1980, ' Depositional sedimentary environments with reference to terrigenous clastics: Heidleburg, German, SpringerVerlag, 2d ed., p. 321-370. Scrudato, R. J., 1969, Kaolin and associated sediments of east-central Georgia: Chapel Hill, University of North Carolina, unpublished Ph.D. dissertation, 89 p. Seismograph Service Corporation, 1971, Report on seismograph surveys conducted in Barnwell, Aiken, and Allendale Counties, South Carolina (DP-MS-80-44I): unpublished report on file at U.S. Geological Survey, Doraville, GA, 45 P Siple, G. E. , 196 7, Geology and ground water of the Savannah River Plant and vicinity, South Carolina: U.S. Geological Survey Water-Supply Paper 1841, 113 p. Sirrine Company, 1980, Ground-water re- source study, Sirrine Job No. P-1550 , DCN-001: Unpublished report on file at U.S. Geological Survey, Doraville, GA, 26 P Stephenson, L. W., and Veatch, J. 0., 1915, Underground waters of the Coastal Plain of Georgia, with a discussion of The quality of the waters by R. B. Dole: U.S. Geological Survey Water-Supply Paper 341, 539 p. Stiles, H. R., and Matthews, S. E., 1983, Ground-water data for Georgia, 1982: U.S. Geological Survey Open-File Report 83-678, 147 p. Stockman, K. E., and Pickering, S. M., Jr., 1977, Georgia's mineral industry, progress from a metals to industrial minerals producer (abs.): National Institute of Mineral Engineers proceedings. Stricker, V. A., 1983, Base flow of streams in the outcrop area of southeastern sand aquifer: South Carolina, Georgia, Alabama, Mississippi: U.S. Geological Survey Water-Resources Investigations Report 83-4106, 17 p. Swanson, D. E., and Gernazian, Andrea, 1979, Petroleum exploration wells in Georgia: Georgia Geologic Survey Information Circular 51, 67 p. Thomson, M. T., and Carter, R. F., 1955, Surface-water resources of Georgia during the drought of 1954, part !Streamflow: Georgia Geological Survey Information Circular 17, 79 p. Tschudy, R. H., and Patterson, S. H., 197 5, Palynological evidence for Late Cretaceous, Paleocene, and early middle Eocene ages for strata in the kaolin belt, central Georgia: u.s. Geological Survey Journal of Research, v. ~, no. 4, p. 437-445. U.S. Environmental Protection Agency, 1977, National interim primary drinking water regulations: EPA-570/9-76003, 159 P 50 Valentine, P. C., 1982, Upper Cretaceous subsurface stratigraphy and structure of coastal Georgia and South Carolina: U.S. Geological Survey Professional Paper 1222, 33 p. Van Nieuwenhuise, D. s., and Colquhoun, D. J., 1982, The Paleocene-lower Eocene Black Mingo Group of the eastcentral Coastal Plain of South Carolina: South Carolina Geology, v. 26, no. 2, p. 47-67. Vincent, H. R. , 1982, Geohydrology of the Jacksonian aquifer in central and east-central Georgia: Georgia Geologic Survey Hydrologic Atlas 8, 3 sheets. Zimmerman, E. A., 1977, Ground-water resources of Colquitt County, Georgia: U.S. Geological Survey Open-File Report 77-56, 41 p. 51 APPENDICES County Georgia I I Well Geologic. Survey Latitude- numbers No. loua:itude Name o.:: owner Appendix A.-Reeord of selected wells lu..~ a A, agricultural; D, domestic.; I, industrial; P, public. 8upply; o, observation, Wacer Level: Reported levels are given in feet, me.uured levels are given in feet and cenths; L, airline measure~ot; F, flowing. "lteld: <, less than. Transm.issivity: t, detern.ined fro1:1 aquifer teat; "' estimated from regressioD equation] I I Oa5-160, 175-190 ft. Trans- * missivity 3,100 tt2/d. Screen 120-130, 150-165, 125-235, 255-260 tc. Transmissivity- 4,600 ft2/d. * well 23 in GGS ~1- letin 72. Scr111en 15o-190, 200-210, 270-280 fc. Tu.n511.issivicy z,ouo tr2/d. Scr11en 155-165 fc. Translliss1v1ty 3,200 ttl/d. Screen 120-155, 225-240 ft. Transmissivity ll,OOO ttl/d.* Scnen 127-133 ft. Transmissivity 1,900 tc2/d.* Translllissivity 13,000 ft2/d. 'Ill Sc:reen 100-105, 133-153, 168-173, 228-243 ft. Waterquality analysis, 06-o9-75, Screen 142-147, 157-162 ft. Well 33 in CGS Bullecin 72. Sc:reen 6:./.o-61:10 ft. Water-quality analyds, Ob-LQ-75. PacKer test 139D-14H ft. Water-quality analysis, 01-14-66. Transmissivicy 3,20ll ft2/d.* Screen 437-~62, 4b8-483, 49ti-512, 53b-546, 5>u-572, 67b-6jb, 720-732, 78ij-1:120 ft. Tra.nsDissivity 15,000 ft2/d."~~~ Screen 45o-462, 47D-4!12, 490-505, 515-530, 54D-552, 557-567, 62o-635, 674-694, 711-728, 78G-792, 81G-820 ft. Trans.Ussivity 23,000 ft2fd.. * Screen 513-533, 555-576, 702-723, 829-tl50 ft. Transrdssivity 31,000 ft2/d. t Screen 903-923, 1025-1045 ft. Wacer~ualicy analysis, 05-23-80. Transmissivity 7,100 ft2/d.t Screen 502-524, 545--566, 735--756, 862-8tl3 ft. Translliui.vity 26,000 tt2/d. t Scuan 447-557 ft. County Geora1a Geologic I n::~rs Su~:Y ~~:~~~ Naae or owner Appendix A.--Record of selected wells-Continued [Uae: A, aa:rtcultural; D, dometic~ 1, indu.atrial; P, public tupply; 0, observation, Water Level: Reporced levels are <. given in feet, m&e.aured levels are given in feet and tenths; L, airline JRaaurement; J, flo11ina Yield: less than. translllissivitv: t. determined from aquifer test; * estimated from rearessioc equa:tion] I I I dDrail 0833945 Centet'fille, 2 1965 678 320 10 430 do. 16Ull 3Z.3150- Hu~ton Cq . ITl. 0834100 of Cacm., Sanderfur 8.4., 2 I 08-ZZ-77 I 625 515 10 l80 Midville 17U4 3236040833445 R.obin11 All, 7 440 266 10 292 do . 17Ul0 1816 323716- 0833507 Robins AF~, )A 1969(1) I 305 190 12 Dublin, 275 Midville 17Ul3 3237260833507 Robins ATI, 3 1942(?) I 375 12 275 Midville I6U1 010 323552- 0833&48 Wtt.rner Robins, 5 I 1962(?) I 422 235 12 Dublin, 424 Midville 16V20 2119 3Z3807- 0833743 Warner Robins, 6 I 1968(?) I 4JS 250 12 Dublin- 394 Midville 16T2 1094 322619- 083381Z Pabst Brvery, 4 I 1967(?) I 640 295 12 I6V24 323927083421Z Georgia Forestry Collllllission I 09- -57 I Z85 285 151'1 3228180834729 Jamea Sim.eraon, Peach Co., f&'tll and ranch 186 170 l6V5 3238370814118 Centerville, 3 510 370 10 l6T7 2159 J22758083445Z Perry, 3 630 320 10 16T5 3277220834419 Prry, I 4&5 )14 10 Dublin, 300 Midville Dublin- 470 Midville 397 do . 455 Midville Dublin- 380 Midville 293 do . 17U8 3236450833!118 Robins AFB, Old 5 1943(?) I 370 200 12 Dublin, 296 MidvUle -60.7 -40 -33.0 -105 -25 -24.1 -66 -68.3 -111 -122.1 -101 -88.7 -45 -60 -78.0 -80 -120.2 -68 -68.2 -3B -38.Z L -ZI.6 -30.0 L -24.1 -132 -129.4 -1!6 -117.0 L -5 -12.4 -150 -144.9 -65 -14t! -60 Q -35 -32 44.7 05-23-80 07~9-72 11-13-82 1,200 03- -51 1946 1~24-80 06-10-71 1Q-2Q-t!O OZ-10-54 11-01-76 I0-()5-71 lQ--22-80 06-26-69 07-13-7Z IO-Z:t.-80 1965 10-22-80 08-ll-77 lQ-2Z-80 10-17-51:J 10-Z2-80 07-24-6~ 1Q-22-80 lQ-- -4Z 11-27-62 11--Ql-7b 07-16-6S lQ-28-80 12-18-b7 lQ-22-tW 196Z 1D-Z2-80 lbO 90 800 1,615 25 1,060 1,340 1,300 99U 1,000 1,100 1,040 1,500 75 OZ-20-71 ll--Q8-7b 11-18-69 06-25-64 ll--Q4-7& 07-02-U 07-24-6'1 70 1,000 1,060- 1,500 1,080 755 50.4 " Screen 292-302, 395-415, 434-444, 455-465, 4t!4-494 ft. Screen 505-535, 555-585, 695-705, 730-750, 815-850 ft. Tranndsaiviry 21,000 feZ/d. t Open Aole 120-320 f r. Open hob, 3Q-J5 lt. Well Z6 in ~s &ullectn 64. 6,2 47.1 5Z 17.3 30.3 2l.b 44.9 41.3 33.0 45.1:$ 69.3 44.5 Screen 145-150 fr. Transllissiviry 3,900 fc2/d.* Sc:reen 185-195, 2t!5-295, 345-365 fr. Tran&llisslvity 26,000 ft2/d. * Well 7 in GGS Bulletin 72. Screen 330-340, 361)-380, 405-415, 46Q-480 ft. Tran.ll.issivity 29,000 ft2/d. * Screen 9o-95 fc. Tran.flllsaiviry 10,000 ft2/d. Screen 3Z(J-330, 34Q-350, ldo-t.20, 510-520, 5~Q-600, b30-640 fc. Warer-qu.ality an~~.lysis, 0.4-19, Zl-7!11. Trans1111n1vicy 17,000 feZ/d. Screen 32Q-l30, 648-67ts fe. Trans.U.ssivity .. 12,000 tt2/d Screen 515-575, 605-615 fr. Transll.iutvity 29,000 tt2/d.t Sc:reen 266-286, 315-3Z5 ft. Translllissivity 23,000 ftZ/d.* Screen I9(}-210, 285-305 fr. Transmissivity 20,000 ftz/d.t Well 3 tn GGS Bulletin 72. Screen 235-245, 270-280, 349-354, 366-371, 392-412 fr. tre.nsmlssivity 26,000 fr2/d.* Sc:reen 25D-260, 290-310, 391)-400, 415~25 ft. transadssivley 39,000 ft2/d.* Screen Z95-300, 310-330, 34o-360, 438-443, 510-52U, 56ll-565, 58Q-5t!5, 600-630 ft. Transnalssivicy 32,000 ftl/d. t Well 10 in GGS Hulletin 72. 27.t! 53.7 51.9 23.0 23.0 Screen 17D-175 ft:. Screen 37ll-390, 430-440, 48Q-50U ft. Translllis:'llvity 16,000 ftl/d Screen 32D-330, 390-400, 41U-420, 430-4~0, ~70-5!10, 610-6ZO ft. Transllliulviry 30,000 fr 2Jd. Screen 3lt.-324, 362-367, 376-3!11, 40HI5, 426-436, t.45-465 ft. Trans11isahity 1),000 It2/d.* Sc:reen :wo-210, 260-270, 29~300, 360-370 ft. 11isa1.viry 7,800 ftl/d. t well 4 in GC bulletin 72. Well destroyed, 1971. Tuns- County Well numbers Georgia ...Geologic Survey Latitude- longitud~~: Name or owner A.ppendix A.--Record of selec:ted walb--Continued [llsel A, agric:ultural; D, domestic; I, industrial; P, public supply; 0, obset"vation, Water 'Level: Reported. levels at"e given in feet, measured Levels are given in feet and tenths; t., .airline ~aeasurement; f', flowing. Yiald: <, less than. Transatssivity: t, detendned fro11 aquifer test:; *, estiaated froe regression equation) Date Depth l}epth I Diameter: AltitUdll Water ..level ddlled or odilied. of well (It) of casing (ft) of well (in.) r:f Ulnd IIUJ:fii-CIII Aquifer(s) I Above (+) or below (-) Dt< of land surface (ft) ua,nt.,ment Yield (gal/min) Sp ~:~i hc capac:ity (gal/ll.in/ft) u.. Ke.atk Jefferson I 26M1 26Y8 26l'7 3316270822433 3306400822523 3306290822501 J. M. Huber, 1 05- -65 I 351 192 f. Gresbrecht IUcllilrd JOh1!5on. 1 435 435 08-27-78 I 425 225 Dublin- 10 4" Midville, Gordon 14.5 "5 .... 13.5 382 do. -162 -165.1! -118.2 -145.8 -108 -l:l6.9 05- -6!1 10-20-80 11-13-ltl 10-2U-1!0 0~ -71! 1D-20-I!O 305 1.000 1,250 8.5 16.t. 26Yl 330024- 0822729 J. P. Stevens, AI 540 45D 1D 3!U Dublin -68 1977 1,000 10 JohDJ;C 24VJ. 3453 3:l42090if24302 USGS, Wrightsville Fi~etower TW-1 I Otl- -80 11,780 11,120 355 ltidvllle -f28.& -132.1 Oti-29~0 lD-23-tiO J .... 17X2 2141 325234063315t. Jones eo 1 11- -68 75 35 Dublin- 430 Midville. -!0 -60 L ll-27-btl 10-21-80 l5D 10.1 17WS l8Wl 325225- 08J3148 JQniii:S Co. , 3 !03 " 4!0 do. 325:.!23- Griswold Ele- 0832923 lllentary School 1951! 40 40 24 475 da. -3 -!5 -28.7 04-10-71! 02-20-79 195 10-18-bl) Uut:eoa 23U3 323121- Amc-i c:11n H'(lmf 0S251211 PrudiU!CII Co I 690 2307 3232490tJ2SH9 hst Dublin, 1 12- -so 1 sao 455 01 ~ 23U4 1031 3232110825:1.04 East Dublin, Z 1. .5 662 580 208 Dublin Dubh.n, 24. Midville 230 l>ublin -2.5 -2.0 _,. -51.0 -29 1975 11-16-76 9D5 05-ol-75 11-10-76 bOO 04-29-65 645 16.1 23U6 3231000825124 Laurens Park, 3 Mob.asco 604 455 !2 21U4 3524 32303o0830243 USGS 0 L.a.u~s Co,, 1'W-3 01- -82 I 1.685 11,060 21U do . 282 Midville - 04-Ql-7b 10-27-1!0 1,700 32.7 -35.8 Ul-28-tJZ 2102 32303D- !;a, D.O.T. ti7A 2 , 0830l46 Rest stop ~o~ell I 09- -68 I 509 229 Dublin, Cordon, ZIU ,l11.c~ nun 48 -52.7 09-03-68 01-21!-82 160 Pulaski 21US 18S3 32303U- uses. Laurens 0830240 Co., 'N-1 11-QS~O] ij()() 800 6,4 282 Dublin 3216150832800 Hawkinsville, 1 1959 473 .,, 225 do . -33.9 01-28-8:.! 1959 250 F 10-)0-80 1,200 60 18S1l! 321656- 0832750 Rawk.insville 450 228 do. 03-16-43 10-30-tiO 25U l8TI 18Sl0 Richmond I 29ti1H 2':i8Bl 2gM1 30AA4 27M2 2gAA3 35 U 526 3222450832901 3222450832tl00 3325290820039 331:50>01!20055 3318380820557 33152508157.47 33212Q0821630 3319Qg082054Q uses. Arrowhead cest well, 1 I 09- -8111,560 970 E'ort:als Co. 03- -81 I szo 325 llic:bmond eo., 9 I 12- -st! I uo 90 Richmond Co. 0 10 I 09- -66 85 55 aeph:dbah, 1 Mcllean, 2 01:-()3-55 1 295 2" ... 1967 m Fe. Cordon, 1 Hephzibah, 3 200 190 04-22-74 I 484 319 36,24, !2 !2 334 Hidville Dublin, 238 Gordon Dublin- !<0 Midville ,.. do . ... 432 Dublin- Mi.dvllle, 293 Gordon Dublin- 434 Midville 410 do. -56.7 +1.15 -13 -!6 -14.3 -39.7 -17tl -191!.3 -121 -121.2 -62.7 -62.6 -173 -177.4 05-}2-ijl 04-22~1 12-od-51! ll-2l-7b og-20-t.6 11.}-22-ijO 02-03-55 11-16-78 06- -7'} 1Q-22-tW ll-24-76 10-24-I!U 04-23-74 1D-2l~O 60 1,080 275 810 !25 40 255 22.4 6.! 27.9 5.7 0.7 3.9 Screen 192-202, 215-220, 232-241:, 305-310, 334-349 ft.. Tranll'rllissivity ... S,lOU ft2/d. * Slotted casing 235-435 It. Sc:reen 225-392, 392-425 ft. Transmissivity 9,500 ft2/d. * Sereen 450-530 ft. Water-quality analysiS, 01!-20-111. TransrU.ssivicy 6,000 ft2/d.* Scuen 1120-1140, lLb0-121!0, 13:.!01340 ft. Watu:~}!~l analysts, Od-29-~U. Transrrlssi.vit:y 6,700 Screen 35-65 ft. Water-quality analysis, U6-o9-75. Transmilosivity 6,000 ft 2/d. * Screen 63-lOJ ft. Water-quality tu~alysh, 10-18-60. Well 14 in CCS l!.ullet:in ~2. Screen Sdo-590, 6ll4-6lll, 624-629, b42-652 ft:. Tr:an&- * missivit:y 9,300 ft2/d. Screen 455-516, 571-594 ft. Transmissivity 19,000 ft 2/d. * Screen 1060--Wtk.l, 122o-1240 ft. Water-quality analysis, 01-26--82. Ser4i!en 229-234, 335-346, 495-500 ft , Hrolten dt"ill stem in ~11. Screen 45d-470 ft. Tranttuissivicy 34,000 fc.2/d.* Screen !HQ-9ij0, lllo-1130, 1270-121fll It. Water:~~~~!~~ aJUiilysis, 05-12-81. Trans..Usi.vity 7, !00 Screen 3:.!5-335, 345-355, 360-370, l!40-445, 475-480, 501:-510 h. Transm.issivlcy 13,000 ft2fd. Screen 90-110. Trans.Gis,ivity- l,WO ttl/d.* Screen 55-85 ft:. Transmissivity 16,000 fr:.Z/d.* Screen 2tl5-295 ft. Transmissivity - 3,600 ftl/d.* Sc:retn 174-19:.!, 29'1-319, 341-372, 393-434 ft. Screen 190-200 fc. Transmissivity 1!00 fc2;d.* Screen 319-325, 346-367, 381-402, 4311-444, 465--'175 h . Trans,.issivity 2,b00 ft2/d. * Cou"ty Georgia Geologic n~:~rs I Su~~:y I ~~~~~~~~: Name or owner Appendix A.-Record of aelected velb--<:outinued [Use: A, agricultural; D, do~Mtstic:; I, industrial; P, public supply; 0, observation, Water Le.,el: Reported levels are <, given in teet, measured levels are given in feet and tenths; L, aitl1ne llll!asurament; F, flowing. Yield: less than. Transmissivity: t, detemined from aquifer test; . estimated fro11 re.greaaion equation) dlrlailt:leed or k!Odifted Doefpth orell (ft) I I Doefpth DiaroDfet:er easing (ft) wdl (in.) I I Ale o!tfude land surface. Aquihr(s) I I W'B er l.ave.l --------- - Above (+) or below- (-) Oatrr of laod surface (ft) l.aaaurna"c Yield (gal/min) Specific. capacity (gal/llin/ft) I Us e Remarks lUctu.ond I 2~AA7 29M5 29.U6 lOMb lOAAJl )0AA12 3320l!50820310 E'ine Hill, 1 10- - 72 250 ll4 ,,. llubllnMidvllle -6 -CJ.t. 10- -72 lQ-22-60 255 2.0 3321070820409 Pine Hill, 2 195 96 2l7 do. 331tM)50820ll>9 Floe Hill, 3 .,. 09- -17 25H 14 100 do. u -6.9 04-Q4-74 lD-22~0 510 0 09-28-77 -36. 2 lG-22-ttO 870 5.9 332106081594& ]321370815!112 lUc:haond Co 1 Richmond Co t1 '" 214 255 170 147 do. DO do. 28 -53.2 -19 05-27-71 10-22-80 890 03-15-tiO ll!lO 3316300!!1555l! Kimber ly~:aark PW-4 lCJ!!O 674 387 290 do. -145 09-011-80 505 4.0 30AA.l5 3316070815532 Kimber ly~lark OW-3 1980 618 360 221 do. -69.6 09-08-80 29AA10 129 322322- Gracewood, 1 23 1940 0820320 (Ga. Troa;. School) "' 329 164 do. -15 Otl-06-46 28AA.04 331926- 01 01 30M5 08211139 3315440815718 Port GordOC'l, 4 Pine Hill, 5 (ttcBean, 3) " 85 527 310 do. 165 do. T 08-Ql-45 45 1.4 - 25 - 22.03 07-26-72 10-22-80 310 29M4 332006- Pine Hill, 4 0820005 (Goshen ~ll) 11 - 17-M 162 to lZ 210 do. -41 -41.6 Ot-o7-70 10-22:-80 350 29MB 3318540820708 Rabcock-wileox plant Jline 482 442 305 do. -150 -153 .2 ()g-24-67 10-23-80 210 29884 332309- 0820113 Gracewood, 3 O.--1 130 90 lZ 165 do. -20 -34.4 06-25-74 10-23-110 400 29885 332409- 0820107 Richmond Co., 16 110- -70 122 92 lZ 165 do. -24.3 -38.2 11-12-70 10-22-80 1,050 30.9 308833 332325- 0815920 Monsanto, l ll)J ...t.ft....r., 171 146 lZ 143 do. -12 07-13-74 -29.4 10-21-80 400 8.1 28AA6 3317260820823 Oak Ridg, 1 340 300 412 do. -131 -136.3 11-21-67 lC>-21-80 120 30M2 33204o- -18 08- -64 0815655 Olin, l OS.- -64 315 270 lO l2S do. -3) lG-21-80 600 7. 7 29SA18 3 71 332511- 0820213 Silvererelilt & Ple-.d.ng Hgcs. School 262 lSZ ll 185 do. -132 02-23-54 150 301UJl 3326150815608 Nipro, 8 Of.- -65 103 83 10 127 do. '-9.1 06- -65 tG-21-tiO 3/lO 6.5 30.U14 3116li:S0815608 Killbcrly-(:lark OW-2 1980 637 380 267 do. 30Ml 585 331!:141- 0815712 Continental Can Co. 317 ll6 153 do. 308823 29SlH9 3326490815552 3322370820129 Columbia Nit:ro, 10 Gracew-ood School, 1 lOS " 10 125 do. 150 120 215 do. -112 -52 _,-17.4 -37 09-08-80 03- -59 185 07-20-66 01-QS-79 4-485, 60Hl0, 6~55, 695-705. 740-745 ft. Se;reen 14D-l50, 17C>-190, llD-230, 25Q-270, 290-310. 360-JaO ft. Tranam.f..aivity 9,600 ft:2/d. Screen 281-311 ft. 22Y27 330US70t!25bU3 American Ind. Clay Co., H-5 (Challbers. H.ine) Hlb3 28b 110 260 do. -7.0 07-11-63 670 10.6 Screen llC>-120. l6Q-170, 2Q0-210. 276-286 ft. Tranea.hs1v1ty 6,300 tr.2/d.* 23XJ3 23X32 325~04- Thiele 0824911 Kaolin Co., f--'4 I 01- -71 I 70U 455 10 455 do. 32511110824917 tbJ.ele Kaolin eo . P-1 1 06- -su I 518 407 452 do. -222 -231.9 -205 -222.8 01-15-71 ll-09-78 610 06-1D-50 1D-22-80 400 38 1.5 Screen 455-460, 495-500, 55s-560, 605-615 65~660, 675-690 fr. Traoamiuivity 21,000 f"c.2/d. * Screen o\07-417. 484-504 ft. Tranallinivity 4,600 fr.2;d.* 23Yl7 lSU6 330030- 0824711 Or, Gil11ore , 2 433 470 do. -170 1D-15-tJ5 23lC.l3 23X39 " 3257390824tl26 Sandersville, 4 760 535 10 32~06- &nglo-luurte;an 01124932 Clay Co. 2 1973 795 12 211Yl3 152 330139- 0823732 Geors:i.a Forestry eo-.tesion 526 320 470 do. 440 do. Dublin- Midvilh, 385 Gordo a -220 -24t!.3 -211 -135 -159.3 07-03~4 11-()6-81 06-21-73 03-17-4tl 1Q-22-60 400 1,251) 36.4 23.6 Se;reen 535-540, 560-565, 660-670, 694-699, 704-709, * 755-760 ft. Trannduivit.y 21,000 ft2/d. Well 37 in GGS Bulletin 52. Water level deeper ttl.n -300 ft: oo. 1Q-23-80. Trana- misllivity 13,000 ft2/d. * Screen 32()-330, 35Q-355, 375-380, lt4D-445, 46s-4700 49D-500 ft. 24)(5 22Y30 22Y24 33571801123820 Sepco SX 79 (Geisbric:ht) 19110 U,54l 11,136 330142- American Iod. 0IIl5t104 Clay Co., H.-7 11-12-79 I 341 175 10 33013s0825254 ADeriean Ind. Clay Co., P-2.\ 380 3hJ 10 Dublin- Midville, 375 Bue.ent Dublin- 33U Midville 434 do. -127.8 -124.t! -76.9 -211 04-30-80 1D-23-80 10-22-.80 04-28-72 525 1,015 6 29.0 Open bole, 1136-2541 fc. Se;reen 175-185, 2IQ-240, 26()-270 ft. T"tan5111issivity 4,100 ft2/d. * Se;reen 31~330, 340-350, 37()-380 ft. T"tanaainivity 16,000 ft:l/d Count y Georgia I I Wdl Geologic. Survey Wtitude- Qulllbere No. longitude Naue or owne. r Appendix A.-Rec.ord of selected welle--continued l U ~t A, agricultural; D, domestic; I, industrial; P, public. supply; O, o'bii;ervatiou, Water Level: Reported levels are given in feet, c.easure.d b.vels are. given In feet and tenth5; L, airline .e&sureme.nc; F, flowing. Yield: (, l ess than. transraissivity: T, detet"lllined from aquifer test; *, estimated frou regression equation] I I I I I Date Depth Depth Diameter Altitude drilled of of of of or well cuing ~o>ell land GOdified (ft) (ft) (in.) surfaee Aqulfer(s) Water lavel Above (+) or belo11 (-) I land su.rfaee. (ft) Datil of I Yield Spedfic eapac.ity (gal/ain) (gal/min/ft) I Ua:e lt.e~~arks Washington I 22Y26 3301430825807 Americ.au Ind. Clay eo., M-4:S Oublin- -63 262 155 10 330 M:idville -55 06-21-67 07-D3-7b 570 Sc.reea 155-170, 185-200, 22Q-230, 24Q-250 fr. Trans- 7.2 I missivit.y 11,400 fr2/d. * 21Xl6 3Z572208303l0 Thiele Kaolin Co ., A-4 152 140 2611 do. Screen 14D-150 ft. Tranamiuivity 11,000 -39 04-26-76 20 20.0 ft:2/d.* ZlXZO 1811 3357490830045 Aaerican Ind . Clay Co. ( Buffalo China Clay Mine) 370 135 12 320 do. 21Xl0 3259060830233 Englehard, WC-1 302 118 10 300 do. 22Y32 )30151- Al:l.~rieau Ind.. 0825234 Clay Co., P-6 1982 372 280 12,10 400 do. - 112 .2 -104.8 -70 -56 -189 -184.2 06-16-75 11-18-76 510 07-31-5\:1 02-26-79 470 lHJtH~2 11-15-82 d40 5.9 3.2 19.0 Screen 135-1~5. 18D-220, 235-250, 285-290, 355-365 ft. Transldssiviry 3,700 ft2/d.* t~~nf~ij~~~B, 194-204, 286-296 ft. Tran&lds&ivity ... Sc.ree.n 280-310, 312-342, 352-362 ft. Tranaad.ssivity ... 7,200 feZ/d. t 22Y7 3302360825649 Juliau Veal, tear. hole 2 19420) I 114 36 248 do. Screen 36-41, 54-69, 104-114 ft. Well 18 in GGS -17 08-30-42 220 4.0 0 Bulletin 52. Transmisdvity 2,700 ft2/d.t Wilkinson ~ 19W6 1524 325104- Georgia 0831958 Kaolin Co ., 13 12- ~5 I 490 130 10 400 do. 19X13 325253- 0832952 town of Gordon, 1 1 1938 146 40 345 do. 19X3 32524.3- Preeporr Kaolin 0832024 Plant, 2 1963 351 80 350 do. -48 -48 L -18 -20 -126.9 12-Zl-65 1Q-20----ij0 805 09-1~44 65 10- ~3 10-20-80 18.3 4.3 Screen 130-140, 200-210, 235-245, 310-320, 365-375 ft. Transllinivity 11,000 ft2/~.* Water-quality analysb, 06-o9-75. Sereen 40-146. Translldsdvity 2,800 ft2/4.* Well 24 io. GGS Bulletin 52. Screen 80-90, 123-128, 137-142, 16ij-17J, 243-248, 258-261~. 284-294, 312-322, 336-341 ft. 19X6 325327- he~port Kaolin -60 1960 0i:J3Z050 Rese.a["cb well 1960 305 262 390 do. -100.9 lD-20-80 430 5.4 Sc-reen 262-172 fr::. Traruud.uivity 3,400 fr.2/d.* 01 00 20W1 325135 Et~,ibbard Sereen 135-215 f~. Warer-qu.ality analysis, 06-18-68. 0831322 Plant, 10 1966 245 135 12 290 do. -18 04-0tl-66 1,370 13.2 Transmissivir.y 7,700 ft2/d.* 20W39 2257 3251070831329 Eo&lhard Plant, 13 01- -1o I 265 150 12 280 do. -55 09-23-70 -68 L Otl-26-tiO 1,210 13 Screen 15D-210, 245-265 fr.. transmissivity 7,600 ft2/d.* 20W40 3251030831351 ~lehard Plant, 14 11- -73 I 360 160 12 296 do. -5lt.6 -88 lD-Ol-73 02-26-79 1,040 11. 7 Screen 16D-2ZO, 27D-280, 30G-3JO ft.. Tun.smi5s1v1ty,. 6,900 tc2/d. *: 19WZ 3248440831658 J. M. Huber 300 90 320 do. -33.9 -29.5 04-17-69 12-26-7tl Perforated c.asil)g, 9D-300 ft. Translllissivity 5,100 fr.2/d. 1/t 19W4 19W1 )248460831655 3248370831657 J. M. Huber J. M. Kuber 215 115 '" 320 do. 280 280 301 do. ~~~~~nf!i~~~2lJt14D-150, 18G-210 ft. Tranui.ssivity -49.2 04-17-69 705 7.3 -15.6 -11.5 04-17-b~ 12-26-7tl Perforated ca.si"C)g, 7D-280 fc. -e.nuatd.uhrit.)t 6,tJOO ft2/d.. 1./t 21W3 3249330tB0447 town of toouboro, 1 1950 372 235 do. +1.6 1951 375 20W2 19W16 19W3 3248440831105 Town oi lrvinton, old 1 1956 uo 260 380 do. 3251530831948 Freeport i(aolin, P-8 410 280 10 390 do. 3248510831704 J . M:. Hu!Nic 300 300 319 do. -100 -103.2 195~ 1D-21-80 500 Screen 160-UIO f"c: . -85 06- -80 Screen 28D-320, 360-400 ft. Transllisdvit)' 4,700 -87.2 1o-2o-go 900 7.8 ft2/d -31 -28.8 04-18-69 12-26-78 ~~~~~:d~~eing, 90-300 ft. Tranamissivit~ 3,600 20U6 3237470831235 Tow of Allentown 1981 440 320 430 Dublin -171 Otl- -81 315 63.2 Sereeu 32Q-340, 352-362, 375-385, 4ZQ-440 ft. Water:~~!~~ ana.lyds, 08-194U. Transadssivity 35,000 19WS 3252240831954 Freeport Kaolin, P-7 Dublin- 491 210 10 375 Midville -40 Sereen 210-230, 276-266, 353-373, 406-416 ft. Trans- 03-21-75 430 3.3 missivity 2,200 ft2/d. * 21X2 3253510830628 EnJlehard Gib-1 365 328 360 do. -126 Sc.re.en 328-348 ft. Wat.e.r-q_u.ality analysh, 06-lG-75, 02...03-71 100 7.1 04-17-79. Transmissivity 4,400 ftZ/d. * :vx9 325400083124tJ Eaglehard KL-3 352 207 10 370 do. -75 12-11-5tl Sc.reen 207-212, 244-249, 271-276, 306-316, 34G-J45 ft. -99.2 10-21-tiO 505 4.4 Translli.tdvity 2,900 ft2/d.* 21X1 325350083071! Englehard Gib-2 585 280 12 420 do . -130 -145 05-03-71 10-21-80 865 13.7 Screen 280-2~0, 33~340, 352-372, 40o-420, 445-475, 485-495 ft. Transmissivity 8,000 ft2/d. Appendix A.-Record of selected w-alls-Continued [Use: A, agricultural; D, domesric; I, inducrial; P, public. supply; 0, obse rvation, Water Level: Reported leveb are given in feet, meaeured levels are aiven in feet and tenths; L, airline measure~~~ent; F, flO'-'lng. 'field: <, less than . Tcans aiss ivity: f, detetll.ined froe~ aquifer rest; , esciuced from t'llt.(treseion ~llAt:ionl Councy Georgia Well I Geologic Survey ou11.bers No. 1 I I Wilkinson 20W10 - Latitudelona:itude 3245510831005 tl.at~~e or owner Kat Toller Dace drilled "' modified Uepth of well (fr) Depth of casing (ft) Dia~ter of well ( in.) Altitude of land surface Aquifet"(s) I Watu l.eve.l Above (+) or ~low (-) Date of I Yield I Scappeaccifitlyc land sut'face {ft) measurement (gal/min) (gal/min/ft) I Un I Reraarks - - 87 2 l>ublin- 232 Kidvilb +9.tJ +2 09-23-44 10-Zl-t:IU J ( 0.5 - D Well 65 in GGS Bulletin 52. 20X6 I - I 3256280830925 Bbdr.lake Plantation - 28 36 2" do. 21W4 I - I 324532OH3044 7 Toocasbo1:o 190: " ' 310 235 do. 20W43 21Wl - I 3248440831105 - I 3249390830233 lrvinton, 2 Oiwy. 57 well) !nglehard Min. & Cbem., Dixie H.ine, 1 t 'i i l "' 120 - 631 3SO 12 "0 ,. do. do. 19X9 I 19Xl - 1 03823S129S295- - 325429- 0831735 Gordon (196b lol'e.ll) Ivey, 1 1966 267 65 "' 1965(?) 223 205 - 360 do. do. -11.7 -10.1 -6 -5.8 -36 -34.2 -140 -l35.t:l -16 -18.2 -70 09-24-44 10-21-t:IO 09-3()-82 ll-ll-tt2 05-U-82 11-ll-82 11-JU-78 11-11-82 07- -66 10-20-80 1965 - 300 315 1,230 soo - - 26.7 24.4 3.0 3.6 - D Dug wdl. Well 4 in GCS Bulletin 52. Screen 225-240, 252-257, 268-278, 292-302 ft. Water- p qualicy analysis, 09-Ql-82. Screen 120-140, 20Q-220 ft. Water-qualitt analysis, p 05-12-82. Transmissivity 14,000 ft2jd. Sc.reen 350-370, 39D-400, 416-436, 51D-520, 54Q-560, [ 58Q-600 ft. Tran51Ussivity 2,100 fc1jd.* Screen 65-75, 105-110, 135-140, 155-160, 254-264 ft. p Tran1miuivity 2,400 feZ/d.* p Screen 105-213 ft. Water-q_ualicy analysts, 06-18-68. 2QW4./j I - I 324844- Inrinton, Ga. 19Xl0 I 08Jll05 - I 3253260831836 (U.S. 441 vell) Gordon, 3 (1974 well) 191:J2 1974 .., 283 22S 340 - "'' '" do. do. -127 -124.6 - IJ6-02-t:l2 11-11-81 '" 05-13-74 4SO - Screen 225-245, 255-275 ft. Water-quality analysis, p 06-oJ-82. - Screen 185-195, 204-215, 268-273, 290-31!, 32Q-325 ft. p Water-qualicy analysill, 05-16-74. 01 I 19Wl4 I - I 3251160832112 I I Gordon Svc. Co. EPD 'N-6 I I I 1980 204 124 Dublin- I I Midville, ..o Gordon -137.0 05- -!SO - - Screen 124-204 ft. Water-level recorder installed, 0 05-25-t:l). tO I Bechtel Corp., 1973. J. E. Sirrine Co., 1980. w. G. IC.eclt and Assoc1ate5, Inc., 1965. E. r. Oxford, 1968. P. E. t..aHoreaux Assocites, 1969. Appeodix B .-War.er-q~Ulity analyse& for the Dublin, Midville, and Dublin-Kid ville aquifer 1yata., (Analy by u.s. Geological Survey, except aa noted. <, l t:han) Well D.t.t~:= ~ M1ll11rat118 per liter g ! . j ~ f . ! ~ 0 . ~ ;;: ~ ~ tl Dissolved I H.-rd- 1 aolida y 0 !,g,LI> f- f li! '0 ! a ~ .8 u c:Q ~~ ..,, .. ! ~ ~ ~ ~e. ~ Hil ._ I ..~~ .. !-j ~ ::lN ~~ : ~.:~~ 8. J.:!. ~~ 3 ~ ~ .~ e ] K:1crogram5 per litar .~ ~ ~ 6 8 e ~ ! ] g [ ~ ~ number hn~1: ao::- n.il.nu Aquifer(&) .umpl..d Georgia 'Eo.virou.ental Procec::tiou Divhion reco~~~D~endad limiu (R) and at:andards (S) for aafa drinking water, 1977 I ljt~ C'CIUZS.t: 16W2.4 IArutc~q Cork, 5 16Wl8 ICeor,.:.ll Kraft, 1 16Vl6 l:l t.aad.!lir4 011 Co. 17W4 l'1oaa Food, 1 DublinMidville do. do. do. 06-09-75 [10 2.s I 0.2 1 2.4 I 0.7 06-19-68 9.0 I 1 _, I ., I _, 1 1 11-1!1-59 5.6 1.2 .s 4.0 .2 117 06-0!J-75 1 12 1.8 I .1 I 2.2 I .2 ~ u UaeUaz Call:ll!:t liJt% ~~td.ll.l.t O.onP Co.lhp , !! Dublin 06-1()-75 110 29 !.0 1.9 I 2.1 l.ll ~:~ I ~:~ I 1/ ~~~ I ~~~ 15 (R) ~' I~~' I ~~' l~c~ I ~~~ I~~' I~~) I ~s~ ! ~~' !4 l.l 6.4 ' ' 2.4 I o.o I 4.9 16.00 I 37 I 24 '' .l I 2.0 4.0 .o 110 36 I 28 40 !.8 ~ I 1.1 I .03 I 23 1 I .,. ~~5.3l <\19.0 s. 1 439 4s.s 42o.o o 5.! I''' l't., ' 1-1 ., I I o ~ __ 431 4s.3 42o.o I< 88 10 I c 10 I o ., 60 " 68 15 '' .I a I .04 .03 1 110 110 I 11 I l 'l6e [ 116.5 <\23 I .:. .u I <100 I ) ~~' I ~~' I ~~' l~c~ I ~ I fs, I ~' 2,0 (S) 10 (S) 5,000 (a) LaureDII Coun'ty 21U4IUSCS, I..e.urena, TW-3 lltivillo ot-28-82 1 n 7.8 I 0.8 .: I 1.0 I 46 ).ilbo 8.9 I 1.0 I 2.3 56 I 75 123 1 D 1us 146.4 ' 424.9 33 ld l ru rn f'rQw ell !Hi d oll: e r:; [ 1085) Q ,__ () I"' I I POST-P ALOc EN UNITS 23T 1 800' SE s 25T2 R / __ ,.J '-,~ ~' SEA LEV EL :~ [ r f \ LOC ATION OF HYDROGE OLOG I C SECT IONS HYDROGEOLOGY OF THE DUBLIN AND MIDVILLE AQUIFER SYSTEMS OF EAST-CENTRAL GEORGIA. GEORGIA DEPARTMENT OF NATURA L RESO URCES ENVIRONMENTAL PROTECTION DIVISION GEORGIA GEO L OGIC S URV EY NW c 5 00' 23X28 400 1 SEA L EVEL 24V1 SE c 25T2 Prepared in cooperation with the UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICA L SURVEY 1900' 200 0 1 2100 ' 240 0 1 2600' 2700' 10 Vert ica l sca le gren tl y exagger ated EXPLANATION 20 MI LES 400' 3001 200 ' 1 00 ' SEA LEVEL NW D EXPLANAT I ON 900 1 1000 1 1 100 1 30AA13 2100' 2600 ' 27 00' SRP-P1A LOCATION O F HYDR OG EOLOG IC SECTI ON S POST-PALEOCENE UNITS SRP-P5A INFORMATI ON CIRCULAR 74 PLATE 2 List of wells on hydrogeologic sections County Well number Georgia Geologic Survey number Latitudelongitude Name or owner Date drilled or modified Altitude of land surface (feet) Burke 28Xl 3444 3252320821315 USGS, Midville SEXTW-1 06- 04- 80 269 3! Z2 -- 330828- Ga. Power Co. 0814542 Pl ant Vogtle TW-1 03- -72 217 Johnson 24V1 3453 324209- USGS, Wrightsville 0824302 Firetower, TW-1 08-29-80 355 Laurens 21 U4 3524 3230300830243 USGS, Laurens TW-3 12-16-81 282 23Tl 51 322840- 0824530 Grace McCain, I 06- -45 280 Pulaski !BTl 3511 322245- USGS, Arrowhead 0832901 TW-1 04-15-81 334 Richmo nd 30AA1 585 331941- Continental Can 0815712 Company 1959? !53 30AA13 3446 331628- Kimberly-Clark Co. 0815558 Observation 1 1980 287 Treutlen 25T2 730 322313 - 0823234 Gillis, 1 Washington 22Y3 0 -- 3301420825804 American Ind. Clay , M-7 08- - 61 351 ll-12-79 330 23X28 1050 325907- 0824814 Sandersville, 9 05-13-66 450 24X5 -- 3357180823820 Sepco SX79-1 Geisbricht 1980 375 Wilkinson 19W6 1524 3251040831958 Ge orgia Kaolin Co e, 13 12- -65 400 20V4 3165 324257- 0831324 Willis Allen, I 02- -76 413 Aiken, s.c. AK- 438 -- 3329200815250 AK-438, Town of Bath 1974? 240 SRP- P!A -- 3317070813949 Savannah River Plant, PlA 02-04 - 62 288 SRP-P4A -- 3315020814812 Savannah River Plant, P4A 08-07-62 105 Allendale , Al-19 -- S.C . 3302290812649 Al-19, Fred Whitaker Co. 10- -63 162 A1-23 -- Al-66 -- Barnwell, SRP-P5A -- S.C. 330101 0811806 3306470813356 3308340813627 Al-23, Town of Allendale Al-66, Creek Pl antation Savannah River Pl ant, P5A -- 181 12- -78 200 12- -62 208 SE o POST-PALEOCENE UN I TS HYDROGEOLOGY OF T HE DUBLIN AND MIDVI L LE AQU IFER SYSTEMS OF EAST-CENTRAL GEORGIA. Modified from Faye and Prowell ( 1982 )