HYDROLOGIC REPORT HYDROLOGY AND CHLORIDE CONTAMINATION OF THE PRINCIPAL ARTESIAN AQUIFER IN GLYNN COUNTY, GEORGIA by Robert L. Wait and Dean 0. Gregg STATE OF GEORGIA DEPARTMENT OF NATURAL RESOURCES Joe D. Tanner, Commissioner EARTH AND WATER DIVISION WATER RESOURCES SURVEY OF GEORGIA Sam M. Pickering, State Geologist and Division Director PREPARm .. COOPERA110N WITH THE U.S. GOl.OGICAL SURVEY ATLANTA 1973 For convenience in selecting our reports from your bookshelves, they will be color-keyed across the spine by subject as follows: Red Dk. Purple Maroon Lt. Green Lt. Blue Dk. Green Dk. Blue Olive Yellow Dk. Orange Brown Black Valley & Ridge mapping and structural .geology Piedmont & Blue Ridge mapping and struc- tural geology Coastal Plain mapping and stratigraphy Paleontology Coastal Zone studies Geochemical and Geophysical studies Hydrology Economic geology Mining directory Environmental studies Engineering studies Bibliographies and lists of publications Petroleum and natural gas Field trip guidebooks. Colors have been selected at random, and will be augmented as new subjects are published HYDROLOGIC REPORT HYDROLOGY AND CHLORIDE CONTAMINATION OF THE PRINCIPAL ARTESIAN AQUIFER IN GLYNN COUNTY, GEORGIA by Robert L. Wait and Dean 0. Gregg STATE OF GEORGIA DEPARTMENT OF NATURAL RESOURCES Joe D. Tanner, Commissioner EARTH AND WATER DIVISION WATER RESOURCES SURVEY OF GEORGIA Sam M. Pickering, State Geologist and Division Director PREPARED IN COOPERATION WITH THE U.S. GEOLOGICAL SURVEY ATLANTA 1973 This book was composed in IBM Century 10-pt. medium type by Darleen Johnson, and printed and bound by the State of Georgia, Department of Administrative Services. Text paper is 70 lb. offset stock; cover is 65 lb. Carnival Cover. Cartography by Willis G. Hester; design and production by Lynda Stafford and Liz Carmichael. ii CONTENTS Page Abstract . . 1 Introduction 1 Purpose and scope of this investigation 1 Location of area . . . 2 Previous investigations . 2 Acknowledgments and cooperation . 2 Well-numbering system 3 Geology .. 3 Test drilling . 5 Ground-water resources 9 Pumpage . . . . 9 Water-level fluctuations 10 Long-term fluctuations 10 Short-term fluctuations 10 Alaska earthquake 13 Water-bearing zones . 16 Potentiometric maps 20 Changes in head with depth . 22 Temperature of ground water 22 Hydrology . . . . . . . . . 25 Methods used to determine aquifer properties . 25 Aquifer tests 28 Flow tests 28 Industrial shutdowns 28 Analysis of recovery data from industrial shutdowns 36 Long-term water-level decline . 37 Upper water-bearing zone 37 Lower water-bearing zone 37 Both water-bearing zones 37 Results of long-term water-level decline tests 39 iii CONTENTS-Continued Hydrology-Continued Aquifer tests-continued Areal aquifer tests Potentiometric map analyses Analysis of 1964 potentiometric map by the Theis formula . Water-level decline map Leaky aquifer formula . Laboratory analysis . Summary of aquifer tests of principal artesian aquifer and application of data . . . . . Specific capacity Quality of water . . Chloride content of water in well fields City of Brunswick Hercules Powder Co. Brunswick Pulp and Paper Co. Allied Chemical Corp. Chloride content of water from test wells Well 34H132 (test well 2) Well 34H337 (test well 5) Wells 33H127 (test well 3), 33H133 (test well 6), 34H334 (test well 4), and 34H344 (test well 7) . . . . . . . . . Exploration of well 34G1 (Babcock and Wilcox Co.) Area of chloride contamination Movement of the chloride body Plugging wells . . Mixtures of water Lateral sea-water encroachment Residual problems and continuing investigation Summary and conclusions Selected references Appendix A . . . Page 39 39 40 40 42 42 42 48 52 54 54 54 54 56 56 56 56 61 61 65 67 67 68 72 76 76 80 83 iv ILLUSTRATIONS Plate 1. Map of potentiometric surface and areal distribution of chloride, Brunswick, Georgia, August 1962 . . . . . . . . . . . 2. Map of potentiometric surface and areal distribution of chloride, Brunswick, Georgia, November 1964 . . . . . . . . . . . . . Page in pocket in pocket Figure 1. Index map of Georgia showing location of Glynn County 2 2. Generalized geologic section 4 3. Particle-size distribution curves, Hawthorn Formation 6 4. Sketch showing construction of well 34H337 (test well 5) 7 5. Pumpage and water-level declines, 1945-64 . . . . . 11 6. Profiles of potentiometric surfaces for 1880, 1943. 1962, 1963. 1964, and predicted profile for 192 mgd pumpage 12 7. Hydrographs of five wells and rainfall for 1964 . 14 8. Correlation diagram showing water-bearing zones. Glynn County, Georgia . . . . . . . . . . . . . . . . . . . . 15 9. Map of potentiometric surface, Glynn County, Georgia, December 1962 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 17 10. Map of potentiometric surface, Glynn County, Georgia. December 1963 0 0 0 0 0 0 0 0 0 0 0 0 0 18 11. Map showing water-level decline caused by a 36.7 mgd increase in pumpage at Brunswick Pulp and Paper Co., Glynn County, Georgia 19 12. Map of potentiometric surface, Glynn County, Georgia, December 1964 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 21 13. Generalized geologic section, head, and flow from well 34H337 (test well 5) . . . . . . . . . . . 24 14. Graph showing increase in ground-water temperature with depth 27 15. Graphs showing water-level fluctuations caused by flow test and ocean tides in well 34H337 (test well 5) . . . 30 16. Data for aquifer tests, well 34H337 (test well 5) 31 17. Sketch of well 34H337 (test well 5) showing transmissivity as calculated from the specific capacities . . .. 32 18. Graphs showing water-level fluctuations caused by shutdown of wells at Hercules Powder Co. . . . . . . . . . 33 19. Semilogarithmic plot of water-level recovery in well 33Hl27 (test well 3) . . . . . . . . . . . . . . . . . . . 34 20 . Logarithmic plot of water-level recovery in well 33H127 (test well 3) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 35 v ILLUSTRATIONS-continued Figure 21. Hydrograph for well 34H205 (U.S. Coast Guard lighthouse) showing decline of water level, 1960-64 . . . . . . . . . . . . . . . 22. Graph showing theoretical water-level decline in the upper waterbearing zone with respect to distance from a pumped well . . . . . 23. Profiles of potentiometric surfaces for October 1962, DecE>mbE>r 1963, and a calculated profile for December 1963 . . . . . . . . 24. Map of predicted potentiometric surface for a pumping rate of 192 mgd, Glynn County, Georgia . . . . . . . . . . . . . . 25. Graph showing change in specific capacity with time for well 33H104 (Allied Chemical Corp. 4) . . . . . . . . . . . . . . . . . 26. Graph showing change in specific capacity for well 34H78 (Hercules Powder Co. 0) . . . . . . . . . . . . . . . . . . . . . . 27. Graph showing chloride content of water from wells 34H73 (Herctt!E's Powder Co. J) and 34H78 (Hercules Powder Co. 0), 1950-64 . . . . 28. Graph showing chloride content of water from Brunswick Pulp and Paper Co. wells . . . . . . . . . . . . . . . . . . . . . 29. Graphs showing chloride content of water from Allied Chemical Corp. wells . . . . . . . . . . . . . 30. Graph showing chloride content of water from 3 depths in WE'll 34H132 (test well 2) . . . . . . . . . . . . . 31. Graph showing chloride content and hardness of watE'r from well 34H337 (test well 5) . . . . . . . . . . . . . . . . 32. Graphs showing chloride content of water from four tE'st WE'lls 33. Electric and gamma-radiation logs, current-meter traverses, and water-bearing zones for well 34G1 (Babcock and Wilcox Co.) . . . . 34. Diagram showing contamination of nearby wells by upward movE'ment of brackish water through well bore of 34G1 . . . . . 35. Graph showing chloride content of water from selectE'd wells, 1960-64 . . . . . . . . . . . . . . . . . . . . 36. Relation of velocity of ground water to hydraulic gradient . 37. Graphs showing chloride content and head in well 34G3 (1\lassey) 38. Sketch of the hydrology of a hypothetical relief well system . . Page 38 44 46 47 49 53 55 57 58 59 60 62 63 64 66 70 71 77 vi TABLES Table 1. Construction features of test wells . 2. Estimated total pumpage, Glynn County, Georgia, 1959-1964 3. Packer test data from well 34H337 (test well 5) 4. Water temperatures and ground-water gradients 5. Aquifer constants determined from flow tests 6. Aquifer constanst determined by Cooper-Jacob modified and Theis nonequilibrium methods from recovery of water levels . . . . 7. Aquifer constants determined from long-term water-level declines 8. Apparent transmissivity from potentiometric maps . . . 9. Physical and hydrologic properties of cored samples from wells 33H114 (Brunswick Pulp and Paper Co. 7), 34H132 (test well 2). and 34H337 (test well 5) . . . . . . . . . . . . . . . . . 10. Summary of aquifer tests of the principal artesian aquifer exclusive of flow tests . . . . . . . . . . . . . . . . . 11. Well construction and specific capacities of selected wells 12. Chemical analyses of ground water, Glynn County, Ga. 13. Calculated mixtures of sea water and average native fresh water to the chloride content of water from three contaminated wells . . . . 14. Calculated mixtures of contaminated water from well 33G3 (1\lassey oil test) and fresh water from well 33H16 (Satilla Shores Subdivision) to the chloride content of contaminated water from several wells . . 15. Calculated mixtures of contaminated water from well 34G1 (Babcock and Wilcox Co.) and fresh water from well 34H94 (city of Brunswick, South Shipyards), August, 1959, to chloride content of water from well 34H94, August, 1963 . . . . . . . 16. Calculated mixtures of water from well 33H127 (test well 3) . . . . Page 8 9 23 26 29 in pocket in pocket 41 in pocket 43 50 in pocket 69 73 7 4 75 Appendix A. New and previously used well numbers in Glynn County, grouped by topographic map quadrangle . . . . 83 Appendix B. Well location map, Glynn County, Georgia . . . . . . . . . . 93 vii HYDROLOGY AND CHLORIDE CONTAMINATION OF THE PRINCIPAL ARTESIAN AQUIFER IN GLYNN COUNTY, GEORGIA by Robert L. Wait' and Dean 0. Gregg' ABSTRACT The principal artesian aquifer in Glynn County yielded 122.3 million gallons of water per day in 1964. This limestone .aquifer, of Oligocene (?) and Eocene age, is at a depth of 500 feet and is about 500 feet thick. A permeable zone at the top ranges from 86 to 140 feet in thickness and a basal permeable zone at a depth,of 860 feet ranges from 16 to 110 feet in thickness. Dense dolomites, from 1,000 to 1,060 feet and 1,350 to 1,385 feet, generally confine a zone of brackish water with as much chloride as 2,000 mg/1 (milligrams per liter). Pressure head increases irregularly with depth from 1.6 feet at 500 feet below the surface to over 30 feet at 1,500 feet. Temperature gradients of fresh water in the 500- to 2,000-foot zone ranged from 0.46 to 0 .67 C per 100 feet, but in the area of chloride contamination at the same general depths, ranged from 1.1o to 1.3 C per 100 feet. Transmissivity o.f t he principal artesian aquifer is 1,500,000 gpd (gall n per day) per fool as delermined by short-term tests, and 1,600,000 gpd per foot by 'long-term tests. Storage coefficient is 0.0006 by short-term tests and 0.004 by long-term tests. Native ground water in the .principal artesian aquifer is of the calcium bicarbonate type, very hard, alkaline, and low in chloride. An "average" water based on 19 analyses had 23 mg/1 chloride, 204 mg /1 hardnes , and 32(') mg/ 1 d isso lv d o!id . In a roughly triangtllar area of downtown Brunswi k , braclUsh wat r in t h zone confined by dolomites is rising t hrough a locally p rous par t of t he upper dolomite and is spreading noxthward in both perm ab.l zan of th prin cipa l art sian aquifer at rates up to 700 feet per year. Any increase in pumpage which would enlarge pr sent con es of depression would accelerate this rate . Els where t he qualiLy of water in wells that had be n contami.nat d has returned to that of "native" water after the parts of the wells which penetrate the chloride-bearing zone had been plugged. None of the high-chloride water comes from lateral sea-water encroachment, nor is any likely to do so in the future. INTRODUCTION The geology and occurrence of brackish water from wells in the Glynn County, Georgia, area were investigated and described by \\'ait (1965 ), who found that fresh water is present in limestone ranging in age from Oligocene(?) to !\Iiddle Eocene, between 500 and 1,000 feet: contaminated or brackish water is present in rocks of Claiborne age between approximately 1,000 to 1,400 feet on the Brunswick Peninsula: and low-chloride magnesiumsulfate water is present below 1,400 feet. \Vater from wells about 1.000 feet deep or deeper and tapping the contaminated zone had a chloride content of as much as 400 mg/1 (milligrams per liter) in 1962. In a small area in the city of Brunswick, water with a chloride content of as much as 1,000 mg/1 occurs between about 500 and 800 feet, in a zone which normally has fresh water elsewhere. The contaminated water is up gradient from, .and moving toward, cones of depression which mark areas of major ground-water withdrawal. Preliminary values for transmissivity and storage coefficient were used in estimating the effect of a proposed 30 mgd (million gallons per day) increase in pumping. PURPOSE AND SCOPE OF THIS INVESTIGATIO:\ The purpose of this investigation was to ascertain more precisely the source. vertical and lateral extent, and rate of movement of known brackish-water con tam ina tion in the Brunswick area. This included determining more precisely the transmissivity and storage coefficient of each aquifer zone, the relative yield of water from each zone, and predicting change from an anticipated increase in rate of pumpage. The scope of this investigation included a test well drilled near the focus Of contamination to ascertain the chloride content of .the water, to obtain head measurements, and to identify the nature of the conditions permitting salty water to move upward into fresh water . In addition, six test wells were drilled to ascertain rate and direction of movement of high-chloride water in the two water-bearing zones. Current-meter traverses were made in selected wells to define the waterbearing zones. Transmissivity and storage coefficient were determined from recovery tests made during five 1 U. S. Geological Survey 1 industrial shutdowns. The temporary decrease in discharge, during these shutdowns, ranged from 20.2 to 62.5 mgd. Transmissivity and storage coefficient were also calculated from a water-level decline caused by an increase in pumpage of 36.7 mgd which occured during a 7 month period. A series of potentiometric maps was analyzed to confirm previous data. Water sampling throughout the county traced the movement of contaminated water. Hypothetical mixtures of water were calculated to determine the sources of contamination. LOCATION OF AREA Glynn County is on the Atlantic Coast of Georgia about midway between Savannah, Ga., and Jacksonville, Fla. (Fig. 1). The county has an area of 423 square miles and its 1970 population was 50,528. Brunswick, the county seat and only incorporated city, is on the Brimswick Peninsula. The peninsula is bounded on the west and south by a network of salt-water rivers and on the east by tidal marsh and the offshore islands of Saint Simons, Little Saint Simons, and Jekyll. These islands form a barrier seaward of the Brunswick Peninsula and the islands are separated by tidal marsh of 6 to 10 miles. A pulp mill, two chemical plants, and several seafood processing plants are_ located in the city, and all use moderate to large amounts of ground water. PREVIOUS INVESTIGATIONS The occurrence of ground water in Glynn County was first described by McCallie (1898, 1908). Stephenson and Veatch (1915) discussed the artesian conditions in the Coastal Plain of Georgia and described several wells in Glynn County. Warren (1944) reported on ground-water conditions in tbe coastal area of Georgia, and on the occurrence of brackish water in the City of Brunswick's F Street well. Several short reports, including those of Stringfield, Warren, and Cooper (1941), Stewart and Counts (1958), and Stewart and Croft (1960), described various aspects of th coastal area. These reports were wide in scope, including most of the Coastal Plain of Georgia, or the coastal area. Wait (1962, 1965) described the geology of Glynn County and also the occurrence of fresh and bxackish waters. Herrick and Vorhls (1963) described the geology of the Coastal Plain of Georgia and showed structure-contour and isopach maps of the geologic formations in the area. Hanshaw and others (1965) discussed the relation of carbon-14 content of brackish and fresh 85' \ \R""!. 1 ..34 -r---t---,--1--:-:-:----;;c-.f--~ \ I ..... (.) 0 Figure 1. Index map of Georgia showing location of Glynn County. water in Glynn County. Herrick and Wait (1955) described the subsurface geology of the coastal area of Georgia and discussed the occurrence of fresh and salt water. Wait and Callahan (1965) reviewed the occurrence of salt water in aquifers along the coastal area of the southeastern United States. Gregg (1966) described the effect of tidal fluctuations on ground-water levels in Glynn County. ACKNOWLEDGMENTS AND COOPERATION The investigation was made by the U. S. Geological Survey in cooperation with the City of Brunswick, Glynn County, and the Georgia Department of Natural Resources, Earth and Water Division. The work described herein was done from July 1962 to June 1965. The cooperation and assistance of city and county officials are gratefully acknowledged. Mr. Bruce Lovvorn, city manager, obtained drilling sites for the test wells. Mr. Wilbur E. Becker, manager and Messrs. Hoyt Brown, G. H. Nelson, and Nobel Sorrow, of Hercules Powder Co., pro- 2 vided assistance by furnishing water-quality data and extended other courtesies. Mr. E. J. Gayner, III, manager and Messrs. Jim Corbett and Robert Flick, of Brunswick Pulp and Paper Co., provided pumpage and water quality data. Mr. J. L. McDonald, Sea Island Co., allowed a free-flow discharge test on well 35H42 and provided wellconstruction data and logs. Mr. Bruce Smith, manager, Allied Chemical Corp., supplied chemical and pumpage data. Mr. J. M. McDermott, Babcock and Wilcox Co., gave permission for exploration of well 34Gl. WELL-NUMBERING SYSTEM The well-numbering system used in this report is based on a 7 112-minute latitude and longitude grid that has been adapted for the ground-water work in Georgia. The state is divided into 7 112-minute quadrangles starting at longitude 85 37'30" on the west and latitude 31o 15'00" on the south. The quadrangles are numbered eastward from 1 to 40, beginning at longitude 85 37'30" and are lettered northward from latitude 3015 '00". Each 7 1h.minute quadrangle is thus identified by the longitude and latitude lines along its south and west sides. To identify a 7 112-minute quadrangle, read right, then up. Thus-, a well in Glynn County in quadrangle 34H is bounded on the west by longitude 81o 30'00" and on the south by latitude 3107'30". The wells within each quadrangle are numbered serially. On maps of Glynn County (Plates 1 and 2), those wells are shown for which hydrologic, geologic, or chemical-quality data are used in this report. GEOLOGY Because the geology of Glynn County was discussed in a previous report (Wait, 1965), it will be treated briefly here. Holocene deposits are dune sands on the sea islands, organic-rich sands in the marsh areas, and surficial sands throughout the county. Herrick (1965) described the Pleistocene of coastal Georgia as a unit and recognized three lithologies: an upper micaceous sand, a middle lignitic clay, and a basal sand. The total thickness of Pleistocene deposits in Glynn County, as shown by Herrick, is about 50 feet. This total is virtually the same as shown by Wait (1965) who did not, however, divide the Pleistocene. Herrick (1965, Fig. 2) also noted the occurrence of a coquina limestone and coarse sand about 40 feet thick between the base of the Pleistocene and the top of the blocky clay (Upper Miocene) which he assigned to the Pliocene (? ), and considered to be equivalent to the Charlton Formation (Pliocene) of Veatch and Stephenson. The Upper Miocene deposits are a dark gray, blocky, sandy, granular, slightly phosphatic clay. Upper Miocene fauna, including pelecypods, gastropods, and foraminifera, were dredged from tidal channels between the barrier islands and mainland and correlated (Darby and Hoyt, 1964) with the Duplin Marl of Late Miocene age, equivalent, in part, to the Yorktown Formation (Late l\Iiocene and Early Pliocene age) in North Carolina and Virginia. Among the pelecypods recovered was Pecten eboreous, which is common at the Doctortown outcrop of the Duplin. Upper l\liocene foraminifera (S. l\I. Herrick, personal communication) were present in the interval of -10 to 150 feet in a well on the south end of Sapelo Island, immediately north of Glynn County. The Hawthorn Formation. as used here, consists of fuller's earth, clayey silt at the top. sand, sandy limestone, phosphatic sandy limestone, and thin dolomite beds. The bed of fuller's earth. clayey silt and a phosphatic sand immediately beneath it are excellent stratigraphic markers throughout the coastal area of Georgia as far south as middle Camden County. but south of there are not as easily recognized. Figure 2 shows the lithology and electric and gamma-ray logs of well 33H127 (test well 3) and illustrates correlation of the logs with lithology, and the position of the correlation points A-D on the gamma-ray log with the lithology. The fuller's earth and clayey silt of the HawthOrn are characterized on the electric log by low resistivity and spontaneous potential. The Hawthorn is important as a confining bed throughout the Georgia Coastal Plain. The gamma radiation increases in the lower few feet of the bed and reaches a peak (point ..\.) in the phosphatic calcareous sand immediately below the clay. The sand produces a large increase in the resistivity and spontaneous potential and a distinct "shoulder'' that is easily recognizable on electric logs. Other lesser peaks occur on the gamma-ray log, but generally well below that of the phosphatic sand. Particle-size analyses (Fig. 3) show that two core samples from well 34H132, from the intervals 165 to 185 feet near the_ top of the fuller's earth bed and from 229 to 232 feet near the bottom and a core sample from well 34H337 from the interval 295 to 308 feet, consist of clayey silt. The coefficient of permeability for the two samples from well 34H132 is 0.004 gpd per sq ft (gallon per day per square foot) in the upper interval and 0.001 gpd per sq ft in the lower interval. This bed keeps salt water from leaking downward to con- 3 HOLOCENE TO PLEISTOCENE 't~ ~--1---- ',, - - - - - -- ~~? t.:! w w A . . . , .... --- - ----<--~.,.,..,_:;_;:;:_::.::_-==-=~ z a...J --'::11 I w a - (.) ~ 0 a z r was present. The w -11 was cored at se \ec:ted depths and pack r L st wen> made at approximately 10 f ol intervals to blain pr ssure meesurrments and water samples from restricted zones. Drilling was done by the conventional rotary method to a depth of 567 feet where the 10-inch casing was set and cemPnl d in place from bottom to top. From 5 '7 to about 1.212 ft L driUing was by airlift re ve r ~ci rculation. Thi. melhod c nsi ts of injecting air fr mac mpressor into the drill st m, au ing wat -r and drill utlings to be su k d from Lh bott m of th E' hole through Lh drill stem, thus keeping the hole clean. In the interval from about 1,030 to 1.080 feet. the formation consisted of loose rhombic, dolomite crystals in a very porous limestone. This interval is usually a hard, dense. dolomitic limestone that is a confining bed and prevents upward movement of high chloride water. The dolomite caved like a sand and much time was spent cleaning the material from the hole. \\'hen the well was 1,214 feet deep, caving again occurred, filling the hole to approximately 1,030 feet. It was necessary to seal out the caving dolomite crystals by placing an 8-inch casing to a depth of 1,189 feet. Drilling was continued by the cable-tool method, using a 6-inch bit from 1,212 feet to a final depth of 1,503 feet. After drilling was completed, the 8-inch casing was cut off at a depth of 936 feet, leaving an 8-inch liner from 936 to 1,189 feet. The well was later modified by placing a cement plug in the bottom from 1,503 upward to 1,420 5 100 90 1I (.!) w 80 3: >- Q) 70 ... w0z:: 60 u... (f) w ....J 50 u 1- 0:: <[ 40 Cl. u... 0 30 w (.!) <[ Iz- 20 w u w0:: 10 Cl. I I I I II I I Sample I 34H337(TW5} y I I II 7-T / v /,'l 295-308 feet I I ;' I I I / ,/_ I , I I l/ / ,/--.......r- Sample 3 v / v I -~, 34HI32 (TW2) 166-185 feet / ./"" Samp Ie 2 [/' 33H 132(TW2} ~v~ 2 29-232 feet ,~ ~' r _/ L ~/ / I I II 0 0.001 w __J a.. ~ .r Co. 36.5 34.0 37.2 Aug., 41.2 Dec., 63.5 77.9 73.7 Allied Chemical Corp. 15.8 15.5 14.4 14.6 Georgia Power Co. 0.2 . .2 .2 .2 12.7 .2 12.2 .2 Other 11.4 14.4 10.0 8 .0 8 .0 8.0 Total 94.43 93.23 90.7 93 .2 115.5 128.4 122.3 1 Based on 11 months ' Estimated from previous year ' Corrected from WSP 1613-E Table 2.-Estimated total pumpage, Glynn County, Ga., 1959-1964 (million gallons per day) 9 Allied Chemical Corp. was reduced about 2 mgd after the installation of a cooling tower and was estimated to be about 12.2 mgd in 1964. Hercules Powder Co. reported their pumpage was 23 mgd in 1964, down slightly from previous years. Two of their wells are now operated by float controls on the water storage tank, and pump only on demand. Other large users in Glynn County in 1964 include the Sea Island Co., 1.2 mgd; Glynco Naval Air Station, 0.62 mgd; and St. Simons Water Department, 0.55 mgd. The 8.0 mgd pumpage labeled "Other" on Table 2 refers to water pumped by several small subdivisions, golf courses, domestic users, and water that flows to waste from flowing wells in the county. Figure 5 shows graphically the estimated pumpage for Glynn County for the years 1945-64, and the resulting decline of artesian pressure in three wells at various distances from the center of the cone of depression. WATER-LEVEL FLUCTUATIONS LONGTERM FLUCTUATIONS The original potentiometric surface in Glynn County was shown by Warren (1944, Fig. 6, p. 26) to be between 60 and 70 feet above sea level. Gradually increasing ground-water use has caused the water level to decline through the years, forming a cone of depression around the center of pumping. The size and depth of the cone of depression are related to the hydrologic characteristics of the aquifer and to the rate of pumping. Because the water-level decline varies inversely with distance from the center of pumping, the potentiometric surface is cone or funnel shaped, being deepest in the center and shallower outward from the center. The development of the cone of depression is shown (Fig. 6) in a series of profiles of the potentiometric surface in Glynn County for 1880, 1943, 1962, 1963, 1964, and for predicted pumpage of 192 mgd. This profile is along a line through Brunswick Pulp and Paper Co.'s and Hercules Powder Co.'s well fields (Fig. 6 ). Instrumental leveling to observation wells was completed in 1964, and the 1962, 1963, and 1964 maps (Figs. 9, 10, and 12) were drawn using the leveled elevations. The profiles show a general deepening and steepening of the cone of depression as pumpage increased and became more concentrated. The center of the cone of depression has shifted westward as pumpage increased at Brunswick Pulp and Paper Co. The west limb of the profiles for 1962 and 1964 are nearly coincident. The extremely heavy rainfall throughout the Coastal Plain in 1964 resulted in a decrease in pumpage and an increase in recharge to the aquifer in the outcrop and other recharge areas. In addition, a slight decrease in pumpage at Brunswick Pulp and Paper Co . and a rise in water levels ranging from 2 to about 6 feet, believed caused by the Alaska earthquake, resulted in water levels recovering to a level near that of October, 1962, prior to the increase in pumpage at Brunswick Pulp and Paper Co . The decline of water levels from 1880 to 1964 ranges from about 65 feet in the center of the cone of depression to about 12 feet in the northwestern part of the county, and 30 feet on the southern part of St. Simons Island. Hydrographs of three wells (Fig. 5) show the decline of water levels in individual wells at three places in the county from 19-15 to 1964. Before 1959, the wells were measured only quarterly or semi-annually but beginning in 1960. they were measured monthly. SHORTTERM FLUCTUATIONS Short-term water-level fluctuations, as considered here, are those that occur in a period of time ranging from a few seconds to as much as a year. They cause displacement of water levels that may or may not be permanent. Such fluctuations include earthquake shoc ks that may last a few seconds or more, tidal fluctuations caused by ocean tides that occur between high and low tide and span approximately 6 hours, fluctuations caused by changes in barom etri press ur . loading of the aquifer ' aus d b a train passin g near a well, or changes in th rat of pumping that occur irregularly, such as a sing! pump r a group of pumps turning on and off. Increased recharge to an aquifer by greater than normal rainfall might also be included. Ocean tides cause water-level fluctuations owing to the added weight of water on the aquifer. At intervals of approximately 6 hours, the ocean tide changes from high to low, causing a corresponding high and low water in a well. The exact time of the high and low water in a well lags the ocean tides, depending upon the proximity of the well to the shore and also to nearby bodies of water that are affected by tides (Gregg, 1966, p. 30, 31 ). The rise and fall of water levels in wells that is caused by ocean tides depends upon the magnitude of the tidal load, the proximity of the well to tidal water, 10 w u ~ 0:: :::J (/) 0 z ~ 20r---------~~--~----------------+---~~--~----~~~~~~~---+~ 0 33HII9 1- 0.5 mi Ie northwest of uwz center of pumpage w w0:: 10~----------------4---------------~~-----------------1------------~~~ awI.J:..:.. I t~- 0~---- LA~N~ D~-----+----S~ UR~F~A~C- E ---+---------~~--~~~------------~ 1w w I.J.... z 10~----------------4------------------+-----------------1~--------+---~~ ~ _j w w > _j a:: 20r-----------------r---------------~-----------------4----------~--~~ w ~ ~ 30L-~---L--~--~--L-~---L--~--4-~--~--~--~--~~---L--~--~--~-J 30~~~~"~~~~~~~~~~~~~~~~~~~"~~~~~~~~ 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 1945-1964 Figure 5. Pumpage and water-level declines, 1945-1964 . 11 A' 70' A .I Origlool polofll iometric slrloce . 188 0 a0 0 16d ..---.... ______ __ ~---~---e--..~..;;'l--~.~.l;.;c-!...!<1,.,oce ~u.,bb 1963 ~ ~-...; ---------.!'.:.a,c,~rt ''-. ometrlc surfoce 1 December 1964 ...... t.:l _ _._ ~ --- ----..P.,e!!~ 10 ..... "_'"_''_1<__u_rrac "- -- -............, ... . ~' r.<-f/ //;"'' 10' J~ ' ', ' '''' . / I ,,', r I I ___, I II j I j I I I 12 10 9 8 6 5 4 3 0 I 2 3 4 5 6 7 8 DISTANCE FROM CENTER OF PUMPING, IN MILES Figure 6. Profiles of potentiometric surfaces for 1880, 1943, 1962, 1963, 1964 and predicted profile for 192 mgd pumpage. the thickness and type of rocks overlying the aquifer, the type of rock constituting the aquifer, the depth of the well, and the depth to which it is cased. The maximum tidal fluctuation measured in Glynn County was 1.7 feet in well 34H42 on Sea Island. The tidal efficiency of a well is the ratio, in percent, of the water-level change in a well compared to the ocean-tide change. Gregg (1966, p. 29) has shown that the tidal efficiency of wells in Glynn County ranges from 2.0 to 19.2 percent and also, that tidal efficiency decreases with depth. Fluctuations caused by ocean tides were recorded in packed intervals at a depth of 2,020 feet in well 33H117 (Brunswick Pulp and Paper Co. 10). Figure 7 shows hydrographs of well 33H127 (test well 3 ), 33H133 (test well 6 ), 34H334 (test well 4), 34H344 (test well 7), and 34G1 (Babcock and Wilcox Co.) for 1964, the interval tapped by each well, and the monthly rainfall at Brunswick. This figure shows the many major water-level fluctuations that occurred in wells in Glynn County during 1964, and the lack of correlation of waterlevel change to local rainfall. These hydrographs illustrate the response of water levels to changes in pumping from both the upper and lower water-bearing zones, the difference in head in the two zones, and the water-level response for the whole aquifer. Wells 33H127 and 33H133 are 10 feet apart and are near the center of the cone of depression. Wells 34H334 and 34H344 are 14 feet apart, about 1 1/2 miles east of the center of the cone of depression, and about 0.15 mile south of the closest well in the Hercules Powder Co. well field. Well 34G1 is at the south end of the Brunswick Peninsula and taps both water-bearing zones. Beginning in January, 1964, water levels were much above normal owing to the Christmas shutdown at Brunswick Pulp and Paper Co. When pumping was resumed, the water levels declined almost immediately to pre-Christmas level. Water levels returned to normal after a momentary surge caused by the Alaska earthquake of March 27, 1964, but they started to rise immediately. After a continuing rise for about 3 weeks, water levels declined, more or less according to the seasonal pattern. In April, a power failure at Brunswick Pulp and Paper Co. caused all the pumps to shut off and water levels rose immediately, but declined just as rapidly once power was available again. Several other power failures in July also produced similar rapid short-term changes in water level. From August 10-24, 1964, Hercules Powder Co. reduced pumpage by 14,200 gpm (gallons per minute) (20.4 mgd) during a general maintenance shutdown, causing water levels to recover throughout the county. The recovery started August 10 and ranged from 2.5 to 10.6 feet in observed wells. Detailed hydrographs of selected wells are shown in Figure 18. During early September, Hurricane Dora forced shutdown of the industrial operations of most plants for approximately a day, and most of the industrial pumping ceased. As a result, water levels rose to their peak for the year. In addition to the cutback in pumpage, unusually high ocean tides caused greater than normal tidal fluctuations. The change in pumpage caused by the industrial shutdown is not known, but probably amounted to at least 70 mgd and possibly as much as 100 mgd. When industrial pumpage began again, water levels declined to their normal pumping levels and remained at about the same level, or increased slightly, until the 196..! Christmas shutdown at Brunswick Pulp and Paper Co., except in wells 34H344 and 34G1, both of which declined slightly in late October and early r\ovember, probably because of nearby pumping. The rainfall at Brunswick, plotted by months at the bottom of Figure 7, shows there is no noticeable response of water levels in the principal artesian aquifer to rainfall in the Brunswick area. Because the aquifer is covered by nearly 500 feet of sediments, some of which have a very low permeability, rainfall only indirectly affects water levels. The water level in Brunswick would generally. correlate at rainfall in the recharge areas, around Valdosta and along the Fall Line. Therefore, recharge to the aquifer in these areas may show up as an increase in pressure head in Glynn County. The time necessary for increased recharge to be felt in Glynn County can be calculated using the equation, t 0 =4a 2 S. The assumed distance to the recharge rr2 T area, a, is 100 miles or 528,000 feet. The average coefficients of transmissivity, T, and storage, S, are assumed at 1,000,000 gpd per ft and 0.0003, respectively. Then: t 0 =4a2 S = 4(528,000f (.0003) = 34days. rr 2T rr 2 (1,000,000) So, theoretically, it would take about 1 month for increased recharge to affect the pressure head in Glynn County. However, no clear-cut time lag is evident to substantiate this. ALASKA EARTHQUAKE On Good Friday, March 27, 1964, at 5:39p.m. 13 18 1- 16 . c--- ~~ lnOu1i iii OI VJUI down ol Brul'\!illlltll Pylp 6 Paper Co. 12 10 , /JPowtr 'OIUI'U ar / 8""'"'" """' 8 ,. r'' Go I 1' ! I I ii I I I I I I l rJ If ~.n 1ndustnol t.nu r 41rll'lQ / Humcone Oo ra Industria I ihul cJa n ol_/ Brunswck Pulp 6 Paper Co ? v 33HI271TW31 JMer""l823-952 feet "\t.v. H---- r-- A N~ ~ Al~:~h ;.r,;~~k 1-" w Ll!<..) 1- LAND 0 a:: ::::> CJl I I SURFACE ? !\ I ~ '""I I I I I I I I I I tr"" ~ rr'll"\ 1- ,_ - 0 z ~ __J ~ G w <..) 1- w z ' \ \ 33HI33(TW6) Interval 520-790 feet v - I I:\ v"\_ - --- -- - ""' ~ "---./ : : - ffi1 2 wu. a:: 10 !~ - - J: t: - 3: .ww.... r' u. z __J w w > __J a:: w ~ 3: 4 0 4 A I 34 H334(TW4) lnlerv-.~..,. .s .. m - L ~ I-- -Tov _of.,;:- ~- }- ~ ' of "'""' ' ~ ~ F ~~ ' Oca la \._ 1 ~ ? ' ';!; Llmutone Middle o.nd lower Miocene (undifferentiated) Ol i QOCene Zonol 1-' 01 ~ ... ~~ -- ""' r,../i'\, . ~f ~ :=~1 Q\r t-~c:ifj) ~ ~~ ~ _ ~ [!= .. ---------- -.-.. - - - - 0 -..-.- ---~- - - -=.::.~- - -- - on~ Upper m1ddle Eocene (undlff: :n2tioted) .,...,.. .......... _ _ 1. . . 19 8' --:, ~ .:. ' / l i ......;--- ,... t_ ;:- \IT r ~ l ~ ( } l..I~"" j_ J~ Figure 8. Geologic section showing water-bearing zones, Glynn County, Georgia. Alaska Landa rd Tim , an eart hqua.k of major magnHude stru k south -central Alaska (Grantz and oth rs 1964, p. 1). The quak , whi h had a mag- nitude of 8. 4 to 8. 6 on th Ri ht r ale, d id ex- t-ensive dam age in Alas ka and caus d tidal wav s along th e Pacifi C as t as far sout h as noxU1ern California. The quake caused water-level fluctuations in wells in Glynn County within 30 minutes The time lag was due to the travel time of the seismic waves. The maximum water-level fluctuation, or hydroseism, in Brunswick was 6.9 feet in well 34G1. Although the float-type water-level recorders are more sensitive than pressure gages, the fluctuations were so violent that the recorder pens came off the charts and the float cables slipped off the pulley wheels . Wells equipped with recording pressure gages gave the best continuous record of the quake and its aftereffect. Most of the float recorders were put back in service Saturday afternoon, March 28. After the quake, some of the wells in Glynn and Liberty Counties that had ceased to flow were re porte d to be flowin g again . Water l vels in Glynn Cou11ty a nd in a well in Wayn Count y IJegan to ris i rnm diately after the quake and continued t do so for about 3 w ks. Th wa t r level d e finitely rose initially be ause of lli quak , but it is un- ertain whether or no t th , 3-w ek dura tion ri e an b completely attributed t o t h ar l hquak e . The 6.9-foo t water-l evel fluctua tion a nd t h e r sultant water-level rise is shown for well 34Gl (Fig . 7) . The hung in water 1-v ls may hav0 resulted from one r m o re of t h fo llo wing cau ses : 1. Possible fracture of hard dolomite confining bed beneath the fresh-water zones allowing freer movement of ground water. 2. An increase in the water-transmitting capacity of the aquifer caused by fractlll'ing along the fault zone west or south of Brunswick, allowing freer movement of water into the area. 3. A d reas in t.he t.orage capacity of the aquifer au s d by pac king of limestone fragments, esp ' ially in Lh ' so fLer bryozoan limestone, causing water lev Is to rise . There was no appreciable diffcrc n e m tb values of the storage coefficient btain d from tests during the 1963 Christmas shu,Ld o wn a t Brunswick Pulp and Paper Co. and Lh Augu t, 1964 shutdown at Hercules Powder Co. WATER-BEARING ZONES Not all of the approximately 500 feet of limestone between the depths of about 500 and 1,000 feet is equally permeable. The increase in the free- flowing discharge and the increase in pressure with depth as a well is being drilled indicates some zones yield water more readily than others. Current-meter tests have been made in all the test wells and also in many industrial and other selected wells throughout the county to determine the depth to and thickness of the water-bearing zones and confining beds. 1\tost of the tests in Glynn County were made with the wells free flowing, or being pumped at a low rate as was done in test wells 3, 4, 6, and 7. Within the limestone there are two main waterbearing zones between depths of about 500 to 1,000 feet. The upper zone is at the top of the Ocala Limestone. It is known to range in thickness from 86 to 140 feet and to yield about 70 percent of the water to wells that tap both zones. The rock is hard to soft, recrystallized, porous, fossiliferous limestone. The zone is recognizable on electric logs as a series of "kicks" to the left on the spontaneous po t.enbal urvP a nd t o lb e ri ght on the r sistiVity c urve . Th top of t h up per zone ca nnot be delermined exactly beca use well casings ar usually s ated in ils t op few fee t. Th e zo1w may be vertically dis oniinuous. Lhat i~. mad e liP of s vera!. thin water-bearing zones. as s h wn by current-meter tests . However. because all currentmeter tests were made with wells free flowing or pumped at a low rate, more exact division is not now possible. The lower water-bearing zone includes the basal part of the Ocala Limestone and the upper part of deposits of Claiborne age. The rock is a hard dolomite and much recrystallized dolomitic limestone. The top of the zone ranges in depth from 860 to 976 feet. It ranges in thickness from 16 to 110 feet and yields about 30 percent of the water to wells penetrating both zones. Caverns are present hetween depths of 880 and 947 feet in three wells at Brunswick Pulp and Paper Co . Although a avero will yield large amounts of water to welts . usually the lower zone is not as produ tive as lhe upper. A current-meter traverse made of a well tapping both zones, when shut-in, shows internal movement of water through the well bore because of differences in pressure between the upper and lower waterbearing zones. The top of the lower zone is at a depth of 940 feet in two wells on St. Simons and Sea Islands, east of the Brunswick Peninsula, and at about 860 to 910 feet in wells in the Brunswick Pulp and Paper Co. well field, just west of the Peninsula. Figure 8 shows the relation of the waterbearing zones and geology on an approximate eastwest cross section. The bottoms of the casings in the wells used in the cross section partly penetrate the upper water-bearing zone. 16 37'30" / I ' ' I I I I I I / / I I r I I J I I ' "J I I I I ., .. ~ EX PLANATION --15--- Potentiometric contour Show!i o!lllud t of potentiometric surface Con lour ln1 ~eNO I 5 feeri datum is mean sea !eve I Lw.1__ 1- -'--'------'---'1"1'" ~ '? ~ () () Figure 9. Map of potentiometric surface, Glynn County, Georgia, October 1962. 17 / ,( /I ; '-_/. I I \ \ I I I I I I I I I I I ,. EXPLANATI ON - -15- - - Potentlomelric contour Sho'l!'rll aullude of potentiometric surface . Contour interval 5 feel ~ datum Is mean no level General direction of ground-water flow 1 Q &MilES ~IW "~'~'--~--~~~_L~I 30 Figure 10. Map of potentiometric surface, Glynn County, Georgia, December 1963 . 18 37'!0" rt' j I (' I ,.---fi--1---\-!--------.--+---,L-------l--~~ / j I (' ;I EX PLANATION --12--- Walr tvel declln lsopllh ~ do:1!rw: ef tJrlt.Uan. 'olllftt 1~t-1 1 1n 1..1, rf'(llfl QctQtar II U to C4C'41111'1hr ~. lupltth ltlllrV11111 2fMI I 0 5o MILES ~~~~~ ---L-L-~-~~ 30' Figure 11. Map showing water-level decline caused by a 36.7 increase in pumpage at Brunswick Pulp and Paper Co., Glynn County, Georgia. 19 POTENTIOMETRIC MAPS A potentiometric or pressure-surface map shows the height, above or below sea level, to which water rises in properly constructed wells tapping an aquifer. Figures 9, 10, and 12 are a series of potentiom t.ri on tour maps of Glynn County. These maps show th h ight, with reference to sea level, that water rises in wells tapping the upper water-bearing zone of the principal artesian aquifer. They were constructed by measuring static (nonpumping) water levels in selected wells that tap only the upper water-bearing zone and which are cased to the top of the limestone. Wells with insufficient casing usually have some internal recharge to sand overlying the lime tone r su1ting in a lower ptessure head than in wells with sufficienL asing to reach the top of the limeston . Wells tapping both water-bearing zon s have a greater pre ure than those tapping only the upper zone, and if only the lower zone is tapped by a well, the pressure is even greater. Although water is withdrawn from both waterbearing zones, there are not enough deep wells tapping both zones to draw a potentiometric map of the combined pressure of both zones. Therefore, these maps represent the potentiometric surface of water in the upper zone that is caused by pumping from both zones. Water levels in pumping wells are, of course, much deeper, ranging from 70 to 80 feet below sea level in the Brunswick Pulp and Paper Co. wells and from 30 to 40 feet below sea level in Hercules Powder Co. wells. Figure 9 shows the potentiometric surface in Glynn County for October 1962. The altitude of the contoured water surface ranged from 10 feet above sea level near the center of the cone of depression around Brunswick Pulp and Paper Co., to 40 feet above sea level in the western and southern parts of the county. The two 25-foot contours form a ground-water divide in the northeast part of the county. North of the divide, water moves northeasterly toward Savannah; southwest of it, water moves toward Brunswick. A cone of depression is formed at Brunswick by the closed contours ranging from 25 feet downward to 10 feet above sea level. The small cone of depression that existed around Hercules Powder Co.'s well field in 1960 (Wait, 1965) could not be defined by measurements made in 1962, although it probably exists. The gradient in Glynn County was steepest on the south side and was slightly more gentle to the west, east, and north. This map represents conditions that existed before Brunswick Pulp and Paper Co. began pumping from three of their new wells; it represents pumpage of approximately 93 mgd in Glynn County. Figure 10 is a potentiometri map forD cember 1963, and repres nts a pumpag of 128 mgd. It shows th effect of a 36.7 mgd jncreas in pum page at Brunswick Pulp and Pap r o. after approximately 1 y ar of pumping at that rate. Th con of depression is deeper and the gradients are steeper than in 1962. Water levels ranged from 10 feet below sea level in the center of the cone to 40 feet above sea level in the southern and western parts of the county. Figure 11 shows the water-level decline caused by the increase in pumpage of 36.7 mgd. It was constructed by subtracting the water levels shown on the December 1963 potentiometric surface diagram from those on the October 1962 potentiometric surface diagram. Declines occurred ranging from about 20 feet in the center of the cone of depression at Brunswick Pulp and Paper Co., to about 2 feet near the boundaries of the county. At the north end of Jekyll Island and westward along the Brunswick River, the 2 and 4 foot decline lines are displaced westward forming a slight nose as suggested by the dashed lines, indicating an area where the decline has not been as great as in the surrounding area. A similar displacement of the 10 foot decline line forms a second nose northward along the Brunswick Peninsula, indicating that the decline there was less than in the surrounding area. Two closed 8 foot lines are within the "nose area." This nose closPly coincides with the area of chloride contamination within the city of Brunswick. The area of decline extends farthest toward the north, ranging to about 6 feet at the Glynn-1\lcintosh County line and extending north into Mcintosh County, where it was about 4 feet. The December 1964 potentiometric map (Fig. 12) shows that the cone of depression is not as deep as in 1963, but has elongated slightly to the northeast. During 1964, excessive rainfall throughout the Coastal Plain of Georgia resulted in increased recharge as well as decreased ground-water use, causing water levels to rise. In addition, the Alaska earthquake of March 27, 1964, caused or contributed to a temporary water-level rise of from 2 to 6 feet in the county. The combined set of circumstances returned water levels to near the level of October 1962, prior to the increase in pumpage of 36.7 mgd (Fig. 9). The cone o_f depression is formed by closed contours rangmg from sea level to 20 feet above sea level and is centered around the Brunswick Pulp and Paper Co. 20 ...... -- ---- ---- EXPLANATION -35-- Potentiometric contour altllude of potentiometric surface. Contour Interval 5 feett datum is mean sea level ~ ' t . .. . J. . . , _, ,_,. . . ._ _!_____.i._J___,_____,~ ~n..u Figure 12. Map of potentiometric surface, Glynn County, Georgia, December 1964 . 21 CHANGES IN HEAD WITH DEPTH During the drilling of well 34H337 (test well 5 ), water samples and pressure-head measurements were taken by means of packer tests made at 100 foot intervals. After the 10 inch casing was cemented in place, drilling was done using airlift reverse circulation and only the clear water that was in the well. A pressure measurement was made between the bottom of the packer and the bottom of the drillhole. At the same time, a pressure measurement was also made in the open hole part of the well above the packer. All measurements were referred to the top of a 16-inch casing, altitude 8.85 feet above msl (mean sea level). The bars on Figure 13 show the pressure measured in the packed interval; the line represents the pressure in the remaining open-hole part of the well above the packer. Packer test 1 was made in a sand above the top of the principal artesian aquifer in the interval 502 to 522 feet before the 10 inch casing was installed in the well, thus no comparison could be made with pressure outside the packed interval. There were only small differences in pressure, ranging from 0.01 to 2.5 feet (Table 3), between the packed intervals and the remaining open-hole part of the well until t h interval 1 87 to 1,503 feet, where the differ n was 18.08 feet. Although the difference in pr ssure between sets of measurements at different depths is not strictly comparable because of tidal influence and the long time between measurements, the differences of the simultaneous measurements are believed accurate. No large change in pressure occurred between 800 and 900 feet, as was found in well 34H132 (test well 2), where the pressure difference was 4.9 feet (Wait, 1965). A split packer prevented measurement of pressure at 1,100 feet, but there was a difference of 3.87 feet between the measurements in two packed intervals at depths of 1,007 and 1,200 feet, possibly indicating some degree of confinement in the interval. However, during the nearly three months between these measurements, water levels throughout the area rose slightly following the seasonal trend; in addition, as much as 1.5 feet of the difference could be accounted for by tidal fluctuations assuming one measurement at high tide, the other at low tide. The free-flow discharge from the well is also shown on Figure 13. The depths at which an increase in discharge occurs coincide generally with the water-bearing zones determined by currentmeter tests. After the 8-inch casing was placed in the well to a depth of 1,189 feet, it was not possible to make accurate measurements of discharge from the part of the well above 1,189 feet. The small difference in pressure between the packed intervals and the open hole part of the well, except in packer test 10, indicates that there is little confine m nt of the water to a depth of 1 ,4 00 fe t . The onfining bed generally present betwee n fresh ahd alty water, from about 1,000 to 1 ,080 f t, is no t pr sent here. The absence of the confining bed allows free vertical movement of the ground water and the brackish water in the 1,050 to 1,350 foot zone moves upward into the 500 to 1,000 foot fresh-water zone . The presence of high-chloride water in the upper water-bearing zone and the lack of confinement indicates that that upper and lower water-bearing zones are hydraulically interconnected. Chloride water moves upward into the upper zone at some point south of test well 5, but north of well 34H99 (Jekyll Island Packing Co.) where the chloride content is about 20 mg/1. TEMPERATURE OF GROUND \\"ATER The temperature of ground water increases with depth. Gutenberg (1959, p. 123) found that in oil field areas, the earth temperature increased about 1o C (Celsius) per 30 meters of increased depth, or about 1.6 F (Fahrenheit) per 100 feet. The increase in earth temperatures is measured using the annual average air temperature of the area as a starting point. At Brunswick, Ga., the average annual air temperature is 20.7"C (69.2F) according to the U. S. Weather Bureau (v. 68, no. 13, p. 179). The rate of increase in temperature with depth is called the earth temperature gradient. A temperature gradient !or the Glynn County area was established using ground-water temperature measured when water samples were taken during packer tests, and from wells that tapped specific water-bearing zones. The water temperatures in all wells except 34H132 (test well 2) and 34H117 (Brunswick Pulp and Paper Co. 10) were measured with a thermometer calibrated in tenths of degrees Celsius. Water from well 34H 117 was measured with a thermometer calibrated in tenths of degrees Fahrenheit. The water temperature in well 34H132 was measured with a less accurate thermometer calibrated in 1 degree Fahrenheit increments and the results may not be comparable to the other temperatures. All gradients were calculated using the shallowest depth of the interval tested because the current meter tests indicate vertical movement of ground water in these zones (see Table 4 ). The t mperature of water from well points at a depth of 12 to 18 feet was 20.5 C (69 F); the te mperature of water from a well 100 feet deep, cased to 60 feet was 19.4" C (67F). These two 22 Packer Test Date Interval (feet below land surface) Head in packed interval 2 (feet above 16-inch casing Head in 10-inch well (16-inch casing) Difference (feet) 1 6-23-63 502-522 6-27-63 567-607 1 2 7-11-63 680-698 3 7-18-63 776-799 4 8-13-63 878-898 5 8-28-63 987-1,007 6 9-19-63 1,068-1,088 7 12-12-63 1,182-1,200 t-.:1 VJ 1.6 3.55-3.64 3 .93 4.11 4 .92 Packer split, no test 8.77 8 .6 0 3.29 3.92 0.01 3.14 .97 3.87 1.05 4.31 6.34 2.43 6 .01 2.59 8 4-20-64 1,281-1,300 9 5-5 -64 1,383-1,400 10 5-26-64 1,487-1,503 1 Well shut in; packer not used . ~ Datum is top of 16-inch casing, altitude H.H5 fE>et. 13.44 13.06 30.21 Head in 8-inch casing (feet above top of 16-inch casing) 10.09 12.92 12.13 3.35 .14 18 .08 Table 3.-Pacl~er test data from well 34H337 (test well 5) Pliocene(? .... Q) Q) :a3". Q) Q) 0 -o -o 0 -o c: 0 .... Q) :J 0 ....J Q) 0 a. 0 ::J 0 w Q) c: \ \ 0 .0 ( 0 I <..) Q) :J 0 ...J GeoiOQY by S M Herrick o' 100' 200' 300' 400' EXPLANATION D . Send Grovel ~ Col co reous sand F::?::::=3 ~ Cloy ~ Limestone ~ Dolomite GR Gommo-rodiotion curve When more then one curve is shown, curve on left is least sensitive S.P Spontaneous-potential curve R Resistivity curve p ~ ' 800' ~ 900' ~ 1000 t?;>;?; t;;, 110 0 - 1200 / Pressure 1n open hole port of well ~ \ V Pressure in pockod mten,ol - 1300 1400 - IVPrmL'" ~/. ~ Po~ked interval :/_. 8 1nch COStnQ , \ --~ ... ~ h \ r-o 15 0 0 0 10 20 30 0 PRESSURE, IN FEET ABOVE 16-INCH CASING 200 400 600 800 FLOW, IN GALLONS PER MINUTE Figure 13. Generalized geologic section, head and flow from well 34H337 (test well 5). 24 temperatures reflect mostly a seasonal difference for the area, but are about the same as the average annual air temperature. The temperature of water from two oil test wells can be used to establish a temperature gradient for the area to depths of about 4,100 feet. The temperature of water from a drill stem test in well 32H33 (McDonald oil test) was 55.4oC (131.7F) in the interval 4,140 to 4,160 feet; that in the Hellemn oil test (Brantley County) about 30 miles northwest of Brunswick was 52.5 C (126.5 F) in the interval 4,109 to 4,120 feet. Using these two temperatures as representative of the overall temperature gradient for the total thickness of Cretaceous and Tertiary sediments above basement rock, the gradient ranges from 0.8C (1.5F McDonald) to 0.8C (1.4 F Hellemn ). These gradients are plotted on Figure 14, as are other temperature measurements. The ground-water temperatures from well 34H 132 (test well 2) range from 26.1 oC (79 F) in the interval 540 to 560 feet to 28.3 C (83 F ) in the interval 1,679 to 1,703 feet. The gradients calculated from these temperatures are 1.0 C (1.8 F) and 0.45C (0.82F) per hundred feet respectively. The higher value appears to be abnormal however and may have been caused by cement behind the casing that gives off heat as it hardens. However, the temperature was 26.7C (80 F) in the interval 576 and 600 feet and the gradient is 1.0 C (1.9 F) per 100 feet which appears to verify the previous gradient. Water from wells 34H110, 34H337, and 34H356 in the contaminated area indicates that the temperature gradient there is greater than in areas of normal (20 to 50 mg/1) chloride. The water temperature in the contaminated area averages 1.3C (2.0F) per 100 feet, which is 0.4 C (0.8 F) greater than the overall gradient shown by the two oil test wells, and greater than from wells elsewhere in the county. Water in the contaminated area had a temperature indicative of a depth of about 1,600 feet. Undoubtedly some cooling occurs as the brackish and fresh water mix, thus a source deeper than 1,600 feet is probably indicated as the depth from which the high chloride water originates. HYDROLOGY To understand an aquifer's productivity, it is necessary to measure the rock's ability to transmit and store water. The transmissivity, T, is a measure of the aquifer's water-transmitting ability. It is expressed as the rate of flow of water at the prevailing water temperature in gallons per day through a vertical strip of the aquifer 1 foot wide, extending the full saturated height of the aquifer under a hydraulic gradient of 1 foot per foot (100 percent). The transmissivity has the units of gallons per day per foot and is determined in the field by aquifer tests. The coefficient of permeability, P, is a related term and is expressed as the rate of flow of water in gallons per day through a cross-sectional area of 1 square foot under a hydraulic gradient of 1 foot per foot (100 percent), at a temperature of 15.5 C (60 F). The coefficient of permeability has the units of gallons per day per square foot (gpd per fe ) and can be measured in the laboratory from samples of aquifer material, but the results must be applied cautiously to field problems. A field coefficient of permeability can be found by dividing the transmissivity, T, by the aquifer thickness, m, in feet. The field coefficient of permeability determined in this manner i~ an average permeability of the entire aquifer, but it may not be representative of any particular part of a heterogeneous or nonuniform aquifer. The coefficient of permeability is understood to be a field coefficient (at the prevailing water temperature). The storage coefficient, S. is a dimensionless constant and is defined as the volume of water an aquifer releases from or takes into storage per unit surface area of the aquifer per unit change in head. Under artesian conditions the water released from or taken into storage in response to a change in head is derived from compression or expansion of the aquifer material and of the water it.self. METHODS USED TO DETERl\llNE AQUIFER PROPERTIES The transmissivity and storage coefficient of the principal artesian aquifer were determined from aquifer t sts and analyses of potentiometric maps. Th aquife r l sts co nsisL of pumping or shutting oif a sing! pumpLng well. or a group of w lis. a nd m -asuring the hange of water J. vels in n arby observation wells. Analysis of potentiomE'tric maps applied analytical methods to a larger area and longer time intervals and the results should be more applicable to the entire area. The coefficients obtained from aquifer tests are based on formulas developed by Theis (1935) that assume ideal conditions necessary for mathematical solutions. Counts and Donsky (1963, p. 41) have summarized these assumptions and the general reliability of results of aquifer tests as follows: "(a) that the aquifer is infinite in areal extent; (b) that it is homogeneous and isotropic-that is, it transmits water equally in all directions; (c) that it is bounded at the top and bottom by imperme- 25 Table 4.- Water Temperatures and Ground-Water Gradients Glynn County, Georgia Average Annual Air Temperature 20.7 C (69.2 F) Well 32H133 Hellemn 33H117 33H117 33H117 33H117 34H110 34H125 34H132 34Hl32 34H132 34H133 34H334 34H344 34H337 34H356 34H127 Depth Interval (feet) 4140-4161 4109-4120 1770-1800 1873-1903 1970-2000 2000-2020 582-682 546-600 540-560 576-600 1679-1703 520-790 802-980 504-770 502-522 581-650 823-952 TOeFmperatuorce 131.7 55.4 126.5 52.5 86 30.0 87 30.6 86.5 30.3 87 30.6 83.5 28.6 77 25.0 79 2 6 .1 80 26.7 83 28.3 78 25.5 80 26 .5 76 24.5 79.5 26.4 83.1 28.4 79 26.1 Temperature Gradient OF per 100 foecet 1.5 0.8 1.4 .8 .9 .5 .9 .5 .9 .5 .9 .5 2.5 1.4 1.4 .8 1.8 1.0 1.9 1.0 .8 .4 1.6 .9 1.3 .7 1.3 .7 2.0 1.0 2.4 1.3 1.2 .6 26 TEMPERATURE, IN DEGREES CELSIUS 21 22 23 24 25 26 27 28 29 30 31 : : - - - ""'~ t--33HI33 ~ .._ .0. .l-r-.34HIIO(Lewis4) "'~ :""~ - I-34H1321TW2) 33HI27~t'- ~3~34 (TW 4) ~ (TW3) ~ ~ I ~ - ~ i'-.9 ~ 9 '~"" ': ~ ~ ~~- r------1-4 f-34H337(TW5)r-----~------~~-----1~----~------~--~~-+------~ 1-33HII71BPIO) T I - I : I i : I : I I i 70 72 74 76 78 80 82 84 TEMPERATURE, IN DEGREES FAHRENHEIT Figure 14. Increase in ground-water temperature with depth . i - : ~ '? 86 88 27 able material; (d) that it has a uniform thickness; and (e) that water is released instantaneously from storage with a decline in head." They further assume "(f) that the discharging well completely penetrates the aquifer and (g) that the flow of water toward the well is radial, or two dimensional. These assumptions are never realized in nature. ... However, tests in many areas have shown that the results of these tests, if used judiciously and with consideration for the geologic framework of the individual areas, provide coefficients in the general magnitude of the actual field conditions." AQUIFER TESTS FLOW TESTS One type of aquifer test involves pumping or allowing a well to flow at a known rate and measuring the drawdown in the pumped well, or in nearby observation wells. Five flow tests were made in well 34H337 during drilling and one each in wells 34G1 and 35H42 (Sea Island, 22nd Street). No observation wells were available for any of these tests. The data were analyzed using the modified nonequilibrium method (Ferris and others, 1962, p. 98); the results are tabulated in Table 5. The flow test made in well 34H337 (test well 5), from the intervals 567-936 and 1,189-1,503 feet, is typical for all the tests . The well was allowed to flow freely at the rate of about 830 gpm for about 3 days. The water level and discharge were measured continuously. The discharge varied as much as 40 to 50 gpm with the stage of the tide (Fig. 15). Tidal fluctuations caused a 0.5 to 0.8 foot oscillation of water level in the well . Analysis of the data is difficult as the tidal fluctuations are several times larger than the resulting drawdown per log cycle, L'ls. The best fitting straight line through these data is only approximate. A transmissivity (Fig. 16) of 850,000 gpd per ft. was calculated by means of the modified nonequilibrium formula (Ferris and others, 1962, p. 98). The results of the other tests are listed in Table 5. Because the summation of small increments of transmissivity for a particular well is equal to the total transmissivity for the well, the selected values were used to give the results shown diagramatically in Figure 17. This is not a completely reliable method of analysis, but it is the only one available to obtain a reasonable estimate of the transmissivity of the brackish-water zone. The flow tests were fairly simple to run, but the results were generally poor. The partial masking of the drawdown of water levels by the tidal fluctuations probably causes the greatest error. Fluctuations due to barometric changes also mask the drawdown. INDUSTRIAL SHUTDOWNS Several times during the course of this investigation, the large industrial water users ceased pumping or reduced their rates of pumping. Every Christmas, Brunswick Pulp and Paper Co. ceases plant operations for several days and reduces their rate of pumping. Several times during the first half of 1964, power failures occurred at this plant and pumping stopped for short periods of time. In August 1964, Hercules Powder Co. shut down operations for plant repairs and pumping was substantially reduced. The recovery of water levels caused by the change in quantity of water pumped was analyzed by a method developed by Cooper and Jacob (1946, p. 526-534 ). This method rectifies the data from a group of pumping wells, each discharging at a different rate and with different on or off times and at different distances from the observation well, so that the group of wells acts with respect to the observation well as a single well at an adjusted distance, discharging at an adjusted rate for a particular time. Figure 18 shows the time off and on of the industrial wells at Hercules Powder Co. and the hydrographs of the resulting recovery of water levels in selected observation wells. !\lost of the hydrographs show the rapid rise of water levels shortly after the first pumps were cut off. An average water level in each well for any particular time was sketched, using the midpoint of the tidal fluctuations. The change in water level was measured from the average water-level trace to a projected water-level trend based on the midpoint of the tidal fluctuations prior to the shutdown. Hercules Powder Co. wells 34H70 (F) and 34H71 (H) pumped intermittently at about the same frequency and pumping rate as before the shutdown, thus their influence was assumed to be negligible during the shutdown. In Figure 19, the specific drawdown (s/Q)n (ftjcfs) is plotted on the arithmetic coordinate, versus the weighted logarithmic mean (r2 ftli (ft2 per hour) on the logarithmic coordinate for well 33H127. The computations to determine the storage coefficient (0.00052) and transmissivity (1,400,000 gpd per ft) are shown also. Figure 20 is a graph of log 10(s/Qli for the same data. This graph is comparea to the type curve as drawn on logarithmic coordinate paper for values of u and W(u) (Wenzel, 1942, p. 87). The values ob- 28 Table 5.~ Aquifer constants determined from flow tests. Interval tested (feet below Well land :;urface) 34G1 34H337 34H337 34H337 34H337 34H337 35H42 589-1,006 567-799 567-1,007 567-1,171 1,189-1,503 567-936 and 1,189-1,503 584-1,040 Duration of test (hours) 70 120 95 300 38 72 350 Average flow rate (gpm) 820 310 500 580 410 830 480 Drawdown (feet) Specific capacity (gpm/ft) 8.00 103 2 .1 8 163 2.13 234 1.57 368 6 .48 66 4 .3 0 194 8 .53 79 Transmissivity (gpd/ft) 3,100,000 840,000 1,900,000 indeterminate 990,000 850,000 480,000 29 c:: ~ ~ -p D c::r-- D .r_--t- -c:::::: - -p lc:::: t-- - c::::: ~ 1-- lc:::: I - - <:: ,_..- t-- -~ -- - c ~--" -p - c:::::: ~ t-- 1'--1- - ""::p c ~ tf-~ - lc:-t-- -~ ~ ~ < r-- ::> r:::..r--..__ _r-- ~ ~ ~ I-.._ c: -1~ '--r,._-_- ~ -- ,... ~ t- p :::: r--1-- :::P <:r~ --1'--- - _.1-- c;;,~ - ::: c::1~ '--rf .- -- ~ .._ f.- c::::: 1'--r-- ~ ~ r--r- ::::::::. r-- ....._ <1~ :::::> <: ~ .., ""c00''. 0>">' < -\ c '_.J _s::: ~ < D p ( <: ~\ ( <:~ ~ ' r."..."... \ ~">' .. ~ 0"' 31: u 0 <,...-./ p iii / p-........ .., "VI' 0 u "' > 0 \ ~ <._ Qj > .!! ~ -~ 0 < lt c"' i 0 ~ u_\ ~'-c lt"' K 'O i.-E: 0 ~ E "'.~::. c- 0-'~ ~ cc( 1r----~ vr-. ~ "OCJ> CI>O Ill :::> c ~ 0 - _J -::::,> ()'\ N - (f) Q ~ Q) .. f 01 0 - z6 <( .....J OT w > f-- I '<>g cycle 0 .f\_ 0 c 0 0 c 0 0~ 0 0 0 0 0- 0 CD Q =830 gpm (average) <( ~4 65= 0 .26 ttl log cycle w w ~ T= 264 a 6s ~ t-' 2 f-- T = (264)( 830) 0 .2 6 - _j ~2 T =850,000 gpd/ft w ....J a::: w f-- ~ ~ 0 I I II 5 10 I I I I II 20 50 100 I I I III 200 500 1000 - I I 2000 5000 TIME, IN MINUTES (t) Figure 16. Data plot for aquifer tPst, well 34H337. 0 10-i n. cosm g SPECIFIC CAPACITY TRANSMISSI 567' I (.) IOJt i 0-2 a::: / N c b / ~ o - , . ~ ' N..... u T-(114.6 Q)W(u) _ I14.6W(u) - s - (s!Ol" aw:: a_ (II 4.6)( J.O)( 448.8 gpm/cfs) T= --------~~~----- 0 .05 f----------i------- - - + - (4. 21 x I0-2f t lc f s) Iw w LL. z z ~ ~ a0 0 .02 /+ Type curve match point W(u}= 1.0 u =0.01 (s/Q)" = 4 . 21 x I0-2 ft/cfs T= 1,220,000 gpd/ft s- Tf(u) _ T(u) 1d - 1.87 ,z - 187 (r2 1' S= (1 ,22x 106 HO.OI}gpd/ft (1.87)(3.88 105 ft 2/hr)(24 hr/day) S= 0 .0007 3: a<:l: ( r 2/t)~= 3.88 x 105 ft2/hr a u Luw-L. 0 .01 105 a_ (j) WEIGHTED MEAN, IN FEET SQUARED PER HOUR (-r 2-/tn ) 1 Figure 20 . Log-log data plot for recovery of watf'r levf'ls in wt>ll 33H127 caust>d by shutdown of wells at Hercules Powder Co., August 10-2-L 196!. 35 tained for the coefficients of storage and transmissivity are 0.0007 and 1,200,000 gpd per ft., respectively. The transmissivity obtained from the type-curve method is slightly less than that from the straight-line method. ANALYSIS OF RECOVERY DATA FROM INDUSTRIAL SHUT DOWNS Because it was not possible to determine the exact quantity of water pumped from each zone, the values of transmissivity (T) and storage coefficient (S) for single-zone observation wells are based on the total pumpage of the industrial well field. However, current-meter traverses show that, generally, the upper water-bearing zone contributes about 70 percent of the water and the lower zone about 30 percent. Thus, the actual T and S values for an upper-zone observation well may be 70 percent of the values listed in Table 6 and for a lowerzone observation well, 30 percent. The single-zone values are then apparent values and are denoted by a prime ( ') designation as T' and S'. The provision is made that the water level in a single-zone observation well behaves as if the aquifer property values are T' and S' when the observation well is influenced by multiple-zone pumpage. The T' and S' values can be adjusted to true values by multiplying them by the estimate of the zonal contribution as follows: 33H133 (test well 6):(upper water-bearing zone); (T') (70 percent)= T (1,400,000 gpd per ft) (70 percent) = 980,000 gpd per ft (S') (70 percent) = S (0.0003) (70 percent) = 0.0002 33H127 (test well 3): (lower water-bearing zone); (T') (30 percent)= T (1,500,000 gpd per ft) (30 percent) = 450,000 gpd per ft (S') (30 percent) = S (0.0005) (30 percent)= 0.0002 These adjusted values for the transmissivity are nearly the same as those calculated values from the respective intervals obtained from flow tests of well 34H337 (test well 5 ). The summation of the adjusted T values for wells 33H133, tapping the upper zone and 33H127 tapping the lower zone should be approximately the same as for an obser- vation well tapping both zones, and is 980,000 gpd p r f + 450,000 gpd per ft = 1 ,400,000 gpd per ft. this om pares well with a on tru ted T value of 1,200,000 gpd per ft. from a flow t.est. on well 34H337 and the av rage T valu s from large industrial recovery tests of 1,400,000 gpd per ft for well 34H337 and 1,600,000 gpd per ft for well 33Hl17, and the composite va lues of 1,40 000 gpd per ft from 33Hll 7 and 34H337 from the August 1964 test. Wells 34H337 and 33Hl17 are the two nearest multiple-zone bservat.ion w lls to wells 33H133 and 33H127. The T' and S' designation will continue to be used for convenience as most of the pumping is from both water-bearing zones and most of the observation wells tap either the upper or lower zone, but not both zones. Wells 33H133 (test well 6), 34H344 (test well 7), and 34H91 (North Shipyards) tap the upper water-b ,ruing zone. The average T valu for all re avery tests for wells 33H133 and 3-1:1!344- are 1 400,000 and 1,200,000 gpd per fl , r spectively. The average T' valu of 1,900 000 gpd er It for w 11 3 H9 is much larger. W II 34Gl, which is near 34H91, taps both zones and also has higher than usual T values from the recovery test and from a flow test. A current-meter traverse of well 34Gl showed 80 perc nL of the water coming from the upper wal. r-bearing zone under free flow conditions. Therefor , the highly productive character of the aquifer underlying the southern part of the Brunswick Peninsula must be due to the high permeability of the upper water-bearing zone there. Well 33H117 (Brunswick Pulp and Paper Co. 10), tapping both water-bearing zan s, is pr bably representative of that well fi ld and gave ar; average transmissivity of 1. 00 ,000 gpd p r ft and a storage of 0 .0005. The higher T value for w e ll 34Gl and the low r T value for well 3.JH337 (als tapping both zones) probably are because of unknown conditions between those observation wells and the pumping wells. T and T' values from the 1964 recovery test are generally higher than those for other recovery tests. No new pumping rate data were available for individual wells at Brunswick Pulp and Paper Co., so the quantity pumped from each well at Christmas 1964 was assumed to be the same as at Christmas 1963, and may account for some of the difference in recovery values. Brunswick Pulp and Paper Co. did, however, reduce their rate of pumping about 6 percent (4.2 mgd) in 1964, but this reduction is not enough to account for the average 36 percent higher T values obtained from analysis of the Christmas 1964 recovery data. 36 There may be some indication that the high T and T' values may have been due to the March 27, 1964 Alaska earthquake that disturbed water levels in the Coastal Plain of Georgia. However, the actual and apparent transmissivity and storage coefficient obtained from the August 1964 Hercules Powder Co. recovery test did not differ substantially from the values obtained from the December 1963 Brunswick Pulp and Paper Co. recovery test and do not support a theory of a permanent change (of at least 6 months duration) in one or both of the aquifer properties. The data from the August 1964 Hercules Powder Co. shutdown are thought to be reliable and the calculated aquifer values are probably correct as listed in Table 6. During the shutdowns, recovery of the water level in well 34G20 on Jekyll Island was two to three days late and was less than should occur using T' and S' values obtained from other observation wells. Well 34G20 is about 44,000 feet from the center of pumpage at Brunswick Pulp and Paper Co. A lag in recovery time of about 1. 7 days could be accounted for because of the distance. However, the complete lag indicates other factors. No boundary condition was found in analysis of the data by the Theis nonequilibrium method. There may be a lateral hydraulic discontinuity between well 34G20 and the industrial well fields. This probably indicates a zone of low per mea bili ty. There may be zones of faulting or fracturing whose planes of movement are filled with fault go ug or other material having a low permeabil ity . If such an area or zone exists, it may explain the anomalous time lag in the transfer of pr ssure across th e zone. As there are no availabl oh rvation wells in the marsh area between well 34G20 and the Brunswick Peninsula, the presence of a zone of low permeability cannot be substantiated. LONG-TERM WATER-LEVEL DECLINE Brunswick Pulp and Paper Co. increased their pumping rate by 36.7 mgd starting about December 2, 1962. The decline in water level was monitored by about 20 wells that were measured monthly and six wells equipped with continuous recorders. A hydrograph of each well was plotted and a water-level trend was determined, based on water levels prior to the December 2, 1962 increase in pumpage. The water-level decline was measured between the projected trend and the actual water level. The projected trend represents the water level in a particular well, had not an increase in pumpage occurred. It is doubtful if this trend can be represented by a straight line, as shown in Figure 21 for well 34H205 (U.S. Coast Guard lighthouse), but any other projected trend would also be an approximation. Logarithmic plots were made of drawdown, 6s, in feet, versus the square of the distance from the observation well to the center of pumping divided by the time since increased pumping started, r 2 /t (fe /day). The data were analyzed using the Theis nonequilibrium formula. The aquifer property values are listed in Table 7. Upper Water-Bearing Zone For the upper water-bearing zone, T' and S' values of 1,500,000 gpd per ft and 0.00-L respectively, were obtained by averaging 17 selected values determined by the type-curve method of analysis. The T' values selected were those whose data plots fit a type curve fairly well. The average coefficient of storage was determined by dividing the summation of the logarithms of each individual S' value by the total number of S' values. This procedure avoided giving undue emphasis to high values of s. Lower Water-Bearing Zone \\'ells 3-lH127 and 3-lH33-l tap only the lower water-bearing zone. The T' value obtained from long-term water-level declines was 2,800,000 gpd per ft for well 34H127, which is much higher than more reliable T' values from recovery tests (Table 6) and also is much higher than the long-term decline T' value of 1,600.000 gpd per ft for well 34H334. The long-term T' value of 1,600,000 gpd per ft for well 34H334 is also high. Little reliance will be placed on these long-term values for the lower water-bearing zone. Both Water-Bearing Zones The T value for well 34G1 is several times larger than the T values for wells 3-lH134 (City of Brunswick, Brunswick Villa) and 34H160 (Sea Island Golf Course) and is probably not representative of the principal artesian aquifer. The T and S values selected as representatives of both zones are T == 1,600,000 gpd per ft and S == 0.004. The average T or T' values obtained from analysis of long-term water-level decline compare closely to those obtained from the recovery tests. The largest departure from true T and S values is again single-zone observation and multiple-zone pumpage for all except wells 34H134, 34H160, and 34Gl. 37 w 22 u ~ 0:: ::> 20 (/) 0 z :3 18 lLI > 0 CD 16 <( ~ I lLI ~ 14 I (Jj 00 -z . ...J l>LI 12 lLI ...J ffi 10 ~ 3t 8 1960 1961 \Brunswick Pu lp and Paper Go. \ i ncreosed pumpoge 36.7. mgd I \ r ~!f2je..c_r..ed -....!:!_oter en -.::. ..:::..t' :!e1 1962 1963 1964 Figure 21. Hydrograph for well 34H205 showing decline of water level due to increase in pumping at Brunswick Pulp and Paper Co., 1960-64. RESULTS OF LONG-TERM WATER-LEVEL DECLINE TESTS The procedure used in determining the drawdown may induce some error in the resulting aquifer constants. If the projected water-level trend is drawn at too steep a slope, then the calculated drawdown will be less than the actual drawdown and the T or T' value will be too large. Conversely, if the projected trend is drawn too flat, the drawdown will be greater and the resultant T or T' value will be too small. Although the slope of the projected trend for any one well may have been drawn too flat or too steep, the average of selected wells in the upper water-bearing zone will probably give the best T' value. The water level in the wells fluctuates seasonally. Because the water-level trend is based on several years of records and is projected as a straight line, no seasonal variation is taken into account. Figure 21 shows the steep decline of water levels in well 34H205 until midsummer 1963 and then a gradual rise of water levels until the spring of 1964. Some of the T, T', S, and S' values are probably influenced by seasonal water-level fluctuations, but the amount of influence is indeterminate. The calculations are based on the assumption that all pumps were turned on December 2, 1962: however, the increase in pumpage occurred over several months. The December 2 water-level decline probably was magnified by putting well 33Hl18 (Brunswick Pulp and Paper Co. 11) into service. Wells 33Hl12 (5) and 33Hl13 (6) were put into continuous service in January 1963, pumping about 4,000 gpm each. Well 33H114 (7) was put into continuous service in February 1963, pumping about 10,000 gpm. December 2 probably best represents the starting date of the increased pumpage and water-level decline. It is not known what, if any, error was introduced into the calculated aquifer values by using this starting date as t 0 , but the error is probably not great. Wells 32H1, 32H26, 33H36, 33H78, 33J22, 34H14 7, 34H328, and 34J1 tap the upper zone. They probably are not cased to the top of the limestone and do not completely penetrate the upper zone. They are designated by footnote 1 in Table 7. A well not cased to the top of the limestone would permit the principal artesian aquifer to lose water to some of the overlying sand and sandy limestone and would give a low water-level measurement resulting in a high T' value. Four of these eight wells gave T' values of more than 2,000,000 gpd per ft and one was 3,600,000 gpd per ft. Well 34H91 tapping the upper water-bearing zone and well 34G1 tapping both zones have very high T and T' values. These wells had almost as high T and T' values from other types of tests. Although the T' value for well 34J9 (New Hope Plantation) is high, flat gradients on the potentiometric maps and the 1962-63 water-level decline map also indicate a high permeability northnortheast of Brunswick. Water-level declines for several wells on Jekyll Island, when plotted on semilogarithmic coordinates, show flat slopes for the early time points. This indicates a lag in the transmission of pressure further substantiating anomalous aquifer conditions between Brunswick and .Jekyll Island. Hydrographs for well 34H1-!7 on the Torras Causeway leading to St. Simons Island, and wells 32J2, 32H26, and 33H3 west and southwest of Brunswick also showed flat slopes for the early times, but this is because the casing does not extend to the top of the limestone AREAL AQUIFER TESTS Potentiometric Map Analyses The term "potentiometric surface" is used to denote the imaginary surface to which water will rise in properly constructed artesian wells tapping a single specific aquifer. A potentiometric map is a graphic representation of the potentiometric surface with contours connecting points of equal water-level altitude. In the previous discussion of the potentiometric maps of Glynn County, the effects of pumping and the eventual shift of the cones of depression were explained and shown. The shape, size, and extent of the cone of depression, like the drawdown near a discharging well, is dependent upon the aquifer characteristics, the quantity of water pumped, the leakage into or out of the aquifer, and the time since pumping commenced. Aquifer properties can be determined from a potentiometric map by constructing a flow net, which is a graphic representation of the pattern of ground-water movement. A particle of water will take the shortest or easiest path as it moves downgradient. This path is called a flow line. \\'hen the aquifer is isotropic and homogeneous, the flow lines are drawn at right angles to the contour lines and are customarily spaced the same distance apart as the contours to form a system of "squares." The sums of the lengths of opposite sides are theoretically equal, hence the term "squares." The flow net is constructed so that equal quantities of 39 water move down gradient between flow lines. In an aquifer that is both anisotropic and heterogeneous, the flow lines and the contour lines do not, in general, intersect at right angles and they f~rm a system of oblique parallelograms whose w1dth-to-length ratio varies from place to place. Results of the analyses of the paten tiometric maps are based on the effect of the total pumpage in the county for the length of time it has occurred. The well methods are based on changes ranging from 20.2 to 62.5 mgd pumpage for a shorter period of time and occurring in a smaller area. Part of the discrepancies in the T' values obtained by these two methods may be this difference in sampling. The potentiometric levels may be influenced by pumpage in adjacent areas that cause a decline that is measured but not accounted for in the quantity of water used in the formula. A flow net constructed on the December 1963 potentiometric map (Fig. 10) shows the direction of movement of water into the cone of depression and especially into the Brunswick Pulp and Paper Co. well field. An equation to determine the transmissivity by a flow-net analysis is presented by Ferris and others (1962, p. 143) as T = Qnd, hnf wher:e Q = flow through the full thickness of the aquifer in gallons per day; nf = n urn ber of flow channels; nd =number of potential drops; h =total potential drop in feet. This equation was applied to detailed flow nets constructed on the December 1960, October 1962, December 1963, and December 1964 potentiometric maps to determine the "apparent" transmissivity, T'. The term "apparent" is used because wells used to draw the maps tap only the upper water-bearing zone, but pumpage is from both zones. The resultant T' values are listed in Table 8. The average T' value determined by flow net analyses for the upper water-bearing zone is about 1,000,000 gpd per ft, whereas the average T' value from the recovery test is 1,500,000 gpd per ft and from the long-term drawdown test is 1,500,000 gpd per ft. Analysis of 1964 Potentiometric Map By The Theis Formula An analysis was made of the 1964 potentiometric map using the Theis equation (Ferris and others, 1962, p. 91 ). Well 33H1 09 in Brunswick Pulp and Paper Co.'s well field was assumed to be the center of pumpage. Rays were drawn from this well to selected outlying wells, or in specified directions; the distance to each contour along each ray was recorded and an average distance to each contour was determined. A plot was made of the head as represented by the contour line versus the logarithm of the average distance. The slope of the line of best fit through the plotted data was used in the Theis equation : T = 527.7Q , where Q = 6s/log cycle 122.3 mgd, or 84,900 gpm. The apparent transmissivity, T', was calculated as 1,100,000 gpd per ft. On the December 1964 potentiometric map (Fig. 12), the gradient is flatter on the southern tip of the Brunswick Peninsula, south of the 20 foot contour line, and in the vicinity of wells 34H91 (City of Brunswick, North Shipyards) and 34G1 (Babcock and Wilcox Co.) than between the 20 and 10 foot contours. This flat gradient is probably caused by the high permeability of the upper waterbearing zone in this area. Well-method aquifer tests on wells 34H91 and 34G1 also gave high values of transmissivity. The gradient steepens northward between the 10 and 20 foot contours in the city of Brunswick, indicating a lower T' value. Well 34H337 (test well 5) in this area and the results of well-method aquifer tests indicate a smaller T value than the well-method aquifer tests on well 34Gl. The flat gradients north of the 10 foot contour indicate a higher T' value between there and the center of pumpage. Water-Level Decline Map Figure 11 shows the decline of water levels due to the 36.7 mgd pumping increase at the Brunswick Pulp and Paper Co. beginning in December 1962. Rays were drawn on the map from the center of pumping (assumed to be well 33H109) at Brunswick Pulp and Paper Co. to selected wells and in selected directions, as was done on the 1964 potentiometric map. The distance in feet from well 33H1 09 to the water-level decline lines was then measured and an average distance to each decline line was determined. The logarithm of the waterlevel decline, in fact, was plotted versus the logarithm of the distance, in feet, and the data were analyzed by the nonequilibrium formula. The average apparent transmissivity of 1,200,000 gpd per ft compares closely with values obtained from recovery tests. The decline lines on the water-level decline map depart from idealized concentric circles and reflect anomalous and anisotropic aquifer conditions. The most striking feature is the displacement northward of the 10 foot line to form a "nose" in the city area. Within this nose are two small areas of lesser decline enclosed by 8-foot lines. These lines 40 Table 8.- Apparent transmissivity from potentiometric maps. Contour Interval (feet) h(ft) Q(mgd) Flow net method nf T'(gpd/ft) Contour Interval (feet) h(ft) Q(mgd) Flow net method nf T'(gpd/ft) December 1960 potentiometric map (Wait, 1962, Fig. 4) 30 to 25 5 25 to 20 5 20 to 15 5 30 to 20 10 30 to 15 15 25 to 15 10 93.2 24 780,000 93.2 - -- 93.2 -- -- 93.2 11 850,000 93.2 7 890,000 93.2 Average 840,000 October 1962 potentiometric map (Fig. 9) 25 to 20 5 20 to 15 5 25 to 15 10 20 to 10 10 93.2 93 .2 93.2 8 93.2 7 Average 1,200,000 1,300,000 1,300,000 I December 1964 potentiometric map (Fig. 12) 1 December 1963 potentiometric map (Fig. 10) .*."..". 20 to 15 5 128.4 -"- -- 15 to 10 5 128.4 22 1,200,000 10 to 5 5 128.4 -- - --- 20 to 10 10 128.4 - --- 20 to 5 15 128.4 - --- 15 to 5 10 128.4 -- --- 20 to 0 20 128.4 6 1,100,000 Average 1,200,000 20 to 15 5 15 to 10 5 10 to 5 5 5 to 0 5 20 to 10 10 20 to 5 15 20 to 0 20 15 to 5 10 15 to 0 15 10 to 0 10 Average 116.0 115.4 112. 110. 116. 116. 116. 115.4 115.4 112. 29 800,000 26 890,000 26 860,000 14 830,000 9 860,000 850,000 Average of four maps .: 1 The quantity pum~a in 1964 was adjusted for withdrawals outside'of the cone Of depression . 1,000,000 may indicate local recharge to the principal artesian aquifer from the underlying brackish-water zone. The steep drawdown gradient between Brunswick Pulp and Paper Co. and the Brunswick Peninsula may be due to an area of discharge being so clc;>se to an area of suspected internal recharge, or to some change in hydraulic properties, such as an area of low permeability that might be formed by a zone of weakness or faulting. No boundary condition, however, was detected in analysis of recovery data from industrial shutdowns . It is concluded that the steep gradients are probably due to discharge-recharge relationship or to possible geologic structure, or to a combination of both. Between the Brunswick Peninsula and the northern half of Jekyll Island, the 2 and 4 foot waterlevel decline lines are displaced westward and may indicate an anomalous aquifer condition. The late response of water levels in wells on Jekyll Island to changes of pumpage in Brunswick also indicate an anomalous condition in the Brunswick RiverSt. Simons Sound area. Leaky Aquifer Formula Because of the probable upward movement of high-chloride waters in the nose area of the waterlevel decline map, an analysis of the map was made using the "leaky aquifer" formula. The logarithm of the water-level decline in feet was plotted versus the logarithm of the average distance in feet from well 33H109 to the decline lines. The plotted points were compared to the " leal{y aquifer" type curve and analyzed by the leaky aquifer formula (Ferris and others, 1962, p. 110). This resulted in an apparent transmissivity, T', of 1 200,000 gpd per ft for the upper water-bearing zone. LABORATORY ANALYSIS Aquifer properties, determined by the U. S. Geological Survey from cored samples from wells 33Hl14 (Brunswick Pulp and Paper Co.), 34H132 (test well 2), and 3~H337 (test well 5), are listed in Table 9. The priq.cipal artesian aquifer transmits water through interstitial pore space, solution openings, and channels. These openings may range from hair size to several feet across. It is difficult to obtain limestone cores that are representative of the aquifer and its water~transmitting ability. The horizontal permeability, PH, should be greater than the vertical permeability, Py, in sedi- mentary rocks and the ratio, Pa /Pv, should be greater than one. Table 9 shows that of the 10 cores having PH /Pv ratios, only four of the ratios were greater than 1.0. It is likely that during the coring operation, cores break along zones of greatest horizontal permeability, thereby losing these zones for laboratory determination. Thus, some of low PH/Pv ratios may be due to the cores not being representative of the aquifer in the interval sampled. Specific yield is the percentage of the total rock volume that is occupied by water yielded by gravity to wells and approximates the storage coefficient if the aquifer is under water-table conditions. The specific yield of t he five samples from the principal artesian aquifer average about 26 percent. The aquifer has, of course, a storage coefficient many times smaller. The storage coefficient of 0.0004, when expressed as a percent, would be 0.04 percent. Therefore, the laboratory determinations of specific yield from cored samples of the limestone aquifer are only of limited value. SUMMARY OF AQUIFER TESTS OF THE PRINCIPAL ARTESIAN AQUIFER AND APPLICATION OF DATA The averages of selected values of the actual and apparent transmissivity and storage coefficient for each type aquifer test, exclusive of the flow tests, are listed in Table 10. Averaging the shortterm and long-term values, exclusiv~ of values from areal methods, gives an apparent transmissivity of 1,400,000 gpd per ft for the upper water-bearing zone. The corresponding apparent storage coefficient is 0.0004 for short-term tests and 0.004 for long-term tests. Figure 22 is a graph of the drawdown in feet versus distance, r, in miles when Q = 1 mgd (700 gpm), T' = 1,400,000 gpd per ft, and S' = 0.0004 (short term) and S' = -o .004 (long term) . This graph can be used to predict the decline of water levels in the upper water-bearing zone caused by pumping 1 day, 10 days, 1 year and 10 years. Because the apparent sto age coefficient appears to change with time, both the short-term and the long-term curves are shown. Because the rate of drawdown is proportional to the rate of pumping, the drawdown for any rate of pumping can be determined. The apparent transmissivity and storage coefficient are applicable only when used in reference to water-level changes in a single water-bearing zone influenced by pumpage from both zones. The actual transmissivity and storage coefficient for 42 Table 10 .-Summary of aquifer tests of the principal artesian aquifer exclusive of flow tests. Type of test Short-term recovery Long-term water-level declines: Monthly hydro graphs Leaky aquifer formula Upper waterbearing zone T'( gpd /ft) S' 1,500,000 0.0004 1,500,000 0.004 1,400,000 Areal methods : flow-net analysis Gradient method Short-cut method Water-level decline map Theis nonequilibrium formula Leaky aquifer formula 1,000,000 1,100,000 1,100,0001 1,200,000 0.021 1,200,000 1964 potentiometric map analysis Theis equation Theis equation 1,100,0001 1,100,000 Lower waterbearing zone T'(gpd/ft) S' 1,400,000 0 .0005 1,600,000 1 0.004 Both waterbearing zones T'(gpd /ft) S' 1,500,000 0.0006 1,600,000 0.004 Remarks P"=3.0 X 10" 1 S' not valid P" =2 X 10-2 Short term Long term 1,500,000 0.0004 1,200,000 0.004 1,420,000 0.0005 0.004 1,500,000 0.0006 1,600,000 0.004 1 Not used in average 43 o.o ..----.---------r-~~~--rn-~--~~r--rrrT:P:y::-"--T::71L:=FfiiT O . l~--------+------------1----------~--------+--.~-------1------~~~--~~--~----------~~-------4 0.2 ~-------+------------r------ (/) 1- w w 0.3~-----+---- LL.. 2 ~ 2 3: 0 0 0.4 **''"" 3: < c,/oc;:rP-----t---:;;,L- .,j,c, .... ,o ~p ,~ 0.5~-------+~~------~r-------_,_ T =I, 400, 000 gpd/ft Q= 1,000, 000 gpd s'= 0.0004 (short term } - - - - - - 1 s'= 0 0 004 (long term) 0.7~------~~~~--~--~~~~~~--------~----~--~~--~~~~---------L----~---L--~~-L~~ 0.1 1.0 10 100 DISTANCE, IN MILES (r) Figure 22. Theoretical water-level decline in upper water-bearing zone with respect to distance from a pumped well. each zone may b estimated by assuming about 70 percent contribution from the upper zone and 30 percent contribution from the low r zone to wells pumping from both zones. The actual transmissivit-y and storage coefficient estimated by t.his m ans are 980,000 gpd per ft and 0.0003 for the upper zone and 420,000 gpd per ft and 0.0002 for the lower zone. The summation of these adjusted values of transmissivity is 1,400,000 gpd per ft. This is ab ut the same magnitude as determined in well 34H337 test w 11 5) by th shutdown t sts but about 12 per ent lower t.han the averag value of 1,520,000 gpd per ft from short-term r covery tests in sel cted observat.ion w lls tapping both zones. The constructed T values from flow tests in well 34H337 are 840,000 gpd per ft for the upper zone and 360,000 gpd per ft for the lower zone (Fig. 17) and total 1,200,000 gpd per ft for both zones. The actual transmissivity for the upper zone ranges from 800,000 to 1,000,000 gpd per ft and for the lower zone, about 300,000 to 500,000 gpd per ft. Because the summation of the adjuSL'd T valu s for the upper and lower zones is about 1,400,000 gpd p r ft and because the recovery T values for well 34H337 average about 1,400 000 gpd per ft, th r valu for both water-bearing zones is taken as ranging frm11 1,400,000 gpd per ft Lo 1,600,000 gpd per ft. The estimate of the storage coefficient appears to increase with time because water is not released instantan ously, as assumed in aquifer test equations, and because of leakage into the aquiler. The soft, porous limestone b tween th upp r and lower zones ontains water but b ause of its low permeability, probably does not release the water instantaneously as assumed in the formulas. An increase in pumpage produces a greater amount of drawdown in the permeable upper and lower waterbearing zones than in the soft relatively impermeable confining unit separating them. The c nfining bed will then adjust to th new condi'Liot'ls imposed on it. by releasing water slowly into the upp 1 and lower wat r-bearing zones until a new equilibrium is reach d. The ~>I w draining of this unit is partly responsible for the apparent increase in the actual and apparent storage coefficients with time. Near the center of the cone of depression the head in the overlying Miocene sand may actually be greater than the h ad in the upper water-b aring zone of the principal artesian aquifer. There is very little pumpage from the overlying materials to lower the head. A relatively impermeable fil'legrained sandy limestone Ln the Oligocene (?) is a good confining bed, but if there is a head differenc across the confining unit, water will be transmitted through it. Thus, water can move downward from the overlying material in to the principal artesian aquifer. The incr ase in the actual and apparent storag c fficienis with time may be due in part, to down ward I akage of water from the overlying materials or to a lesser rate of upward leakage into the overlying materials from the aquifer. This may also partially explain the flat drawdown gradient within the 12-foot decline line on the water-level decline map (Fig. 11). Upward movem nt of bra kisb water from below about 1,050 fe i is the third leakage factor influencing the storage coefficient. High-chlorid water from below 1,050 feet migrates upward into the fresh-water zone. There is some hydraulic continuity between t.he principal artesian aquifer and the underlying material as shown by hydrographs of w 11 34R132, point 3, tapping the interval from 1,053 to 1,103 feet. The bydrograph bows that water in this int rval1 sponds to changes in industrial pumpage at Brunswick Pulp and Paper Co., as do the other two points. Only one well at Brunswick Pulp and Paper Oo. 33H113, is 1,050 feet deep and it usually continues pumping during a Christmas shutdown, thus a water-1 vel fluctuation in the 1,053 to 1,103 foot zone is not caused by this well. Part of this fluctuation may be caused by a change in artesian pressure in the principal fining unit to the underlying brackish-water zone. By definition, the storage coefficient is a fixed parameter for a particular aquifer but. because of the method of det rmining t.hi coeffi i n t, different values may be obtained under different conditions. Because of different conditions, the actual and apparent storag oefficients for the principal artesian aquifer s emingly increase with time because of (1) slow releas of water fr m the confining unit between the water-bearing zones, (2) local downward leakage from the overlying materials, and (3) local upward leakage from below about 1,050 feet. Most of the larger S' values from long-term tests of properly constructed wells are from wells less than 15,000 feet from the assumed center of pumpage; the smallest values are from wells greater than 40,000 feet distance. The decrease with distance may indicate decreasing leakage into the aquifer with distance from the center of pumpage. Although ihe rat of pumpage increased by 36.7 mgd al out D cern ber 1962, several water users decreas d their rat of pumping and the total incr ase for t.he county was 35.2 mgd from 1962 to 1963. The water-level decline produced by the 35.2 mgd increase in pumpage is calculated fort= 1 year, T' = 1,400,000 gpd per ft, and S' = 0.004. This decline wa& subtracted from the 1962 paten- 45 8 8' T " I, 400,000 gpd per It 5"0.004 60"35.2 mgd t =I year I A.pproJlmc e 1ano -sunoc.e - ... ::,....':-. ......... ""'>... ,/"" .. ~ 1 1o ~ 0) JEJL L---~----~~~~----~~----~----~----~----~5----~------3L-----~2----~,L---~L-L---J,------L-----~----~4------5~----J6----~7~----~e--J rd DISTANCE FROM CENTER OF PUMPING, IN MILES Figure 23. Profiles of potentiometric surfaces for October 1962, December 1963, and a calculated profile for December 1963. ' 37'30" .r ,- EXPLANATION --15--- PrediCt~ potenllomtfrlc contour Show altitude of predicted poltntlomelrlc 1urtace. Oalhtd whtrt eonlrol les occurott, Contour lnttryol ~ '"'' datum It mean ..a ltYtl Theoretical well Figure 24. Map of predicted potentiometric surface for a pumping rate of 192 mgd, Glynn County, Georgia. 47 tiometric surface along line B-B' in Figure 9, and i~ plotted as a calculated 1963 potentiometric surface in Figure 23. Profiles of the actual 1962 and 1963 potentiometric surfaces along line B-B' are shown for comparison. The calculated profile compares closely with the actual profile for 1963 on the west side of the cone of depression, but on the east side is from 1.0 foot higher to 5.5 feet lower than the actual profile. This may be due to leakage into the principal artesian aquifer, the construction of the potentiometric maps, and the distribution of pumping. Generally, the calculated surface compares fairly well with the actual surface, thus confirming the validity of the apparent transmissivity of 1,400,000 gpd per ft and storage coefficient of 0.004 (long term). Figure 24 is a predicted potentiometric surface of Glynn County for pumpage totaling 192 mgd. The map was constructed assuming a total increase in pumpage of 70 mgd; 20 mgd increase at Brunswick Pulp and Paper Co. , and 50 mgd on Colonels Island (an industrial site). The pumpage at Brunswick Pulp and Paper Co. was assumed to be from a single well , but that on Colonels Island was assumed to be from three wells, each pumping 16.7 mgd and spaced as far apart as possible to prevent interference and to keep drawdown at a minimum (see Fig, 24 for locations). The amount of decline was calculated after 1 year of pumping at the increased rate and then subtracted from the 1964 potentiometric map to give the predicted potentiometric map. The pumpage figure of 192 mgd used to construct this predicted potentiometric surface is in no way a limiting value placed upon the amount of water that can or should be pumped from the aquifer. It is merely a convenient figure (70 mgd increase over the 122 mgd pumped in 1964) used to illustrate the use of data obtained in this investigation for calculating water-level declines. Comparing the December 1964 potentiometric map with the predicted potentiometric map shows only a moderate water-level decline. Near the areas of pumping, the decline would be 20 to 25 feet. North of the city, at the Glynco Naval Air Station, the decline would be about 10 feet, and in the western part of the county and on Jekyll and St. Simons Island, the decline would be about 10 feet. The decline in water levels due to the hypothetical 70 mgd increase in pumping would increase the amount of leakage into the principal artesian aquifer. Part of this leakage may come from downward movement of water from the Miocene rocks into the principal artesian aquifer near the centers of pumpage. The water in these rocks is of about the same chemical character as the water in the upper zone, thus there is little likelihood of a quality-of-water problem arising from this leakage. However, there would also be an increase in the rate of upward leakage of brackish water from below about 1,050 feet. The brackish water would recharge the principal artesian aquifer at a rate roughly proportional to the rate of water-level decline. It is possible then, that with increased development in new areas, other quality-of-water problems will develop. SPECIFIC CAPACITY The specific capacity, SC, of a well is the yield in gallons per minute divided by the drawdown in feet. The specific capacity of a well dep nds upon its depth, construction, rate of pumping and, to an extent, upon its age and the length of time it was pumped or allowed to flow before the drawdown was measured in addition to t he aquifer's watertransm itt ing abilities . The diameter, length , and kind of casing used and t he d iame ter, length , and roughness of t he open bole below th e casing are fac tors that affect the amount of velocity-head loss due to friction and turbulen ce . Because of the many factors governing the spe i.fic capacity of wells tapping the principal artesian aquifer , no ruleof-thumb can be made to determin the d iameter or depth of a well to obtain a given quantity of water. In general, the specific capacity of a 4-inch well tapping the upper zone ranges from about 10 to about 50 gpm per ft . Table 11 lists the construction and specific capacities of selected wells. All drawdown measurements on this table were made after considerable time had passed following start of withdrawal, so no times are listed. The specific capacities of wells tapping limestone aquifers decrease with long term use. Part of the d crease may be due to t he decline of water levels, but is mainly due t o a gradual clogging of the aquifer by limestone particles and deposition of calcium carbonate on or near the face of t he well bore. Ground-water velocity determined from the 1964 potentiometri map ranges fr om a few hundred to more t han a thousand feet per year; however the ground-water velocity near a producing well may be as much as several feet per min ute and such rela tively high velocity may transport small loose particles of limestone nearer the well bore. The water is supersaturated with calcium with respect to calcite and to a lesser extent, with respect to aragonite (Hanshaw and others, 1965, p. 113). A decrease in pressure may cause some precipitation of the excess calcium in the form of calcite or aragonite on the face of the well bore, or near it. Figure 25 shows the decrease in specific 48 ,_100 0 0 LL.. 90 0: aw.. w 80 1- :::> 2 ~ 70 0: w a.. (f) 60 ~"", 2 0 :J 50 c::r ' , ........ ........ (.!:) 2 40 '-....... ........ >!" 1- ~ 30 a.. c::r (.) 20 (.) LL.. ' ' ,Well ocidizied, ~ .... .... ........... ~ ' .........' " t Uw I 0 a.. (f) 0 1956 1957 1958 1959 1960 1961 1962 1963 Figure 25. Decrease in specific capacity with time for well 33H104 (Allied Chemical Corp. 4) . 49 Table 11.- Well construction and specific capacities of selected wells M - Measured; R - Reported Well Number 34H125 34H132 33H127 34H334 33H133 34H344 34H337 34H337 34H337 34H337 34H337 34H337 01 35H42 0 34G1 34H73 34H73 34H73 34H73 34H73 34H71 34H71 34H71 34H70 34H70 34H78 34H78 34H78 34H78 34H78 34H78 34H78 34H78 Casing Diameter (inches) Depth (feet) Depth of well (feet) 3 546 600 6 540 920 4 823 952 4 802 980 4 520 790 4 504 770 10 567 799 10 567 11,007 10 567 1,171 8 1,189 1,503 10 567 936 8 1,189 1,503 82 580 1,042 123 589 1,006 12 547R 1,051M 12 547R 1,051M 12 547R 1,051M 12 547R 890R 12 547R 890R 124 561R 1,050M 124 561R 890R 124 561R 890R 12 567R 1,025R 12 567R 887R 125 545M 1,014M 125 545M 1,014M 125 545M 1,014M 125 545M 1,014M 125 545R 890R 125 545R 890R 125 545R 890R 125 545R 890R Water-bearing zones tapped Upper Both1 Lower Lower Upper Upper Upper Both Both(+) below p.a.a. Both 1 +) below p.a.a. Both Both Both do do Both 1 do Both Both 1 do Both Both 1 Both do do do Both 1 do do do Rate Drawdown (gpm) (feet) 60 60 60 60 60 60 310 500 580 410 830 480 820 2,530 2,010 1,550 1,750 960 2,420 1,560 1,320 2,300 2,000 2,290 2,100 2,010 1,890 940 680 1,280 1,080 5.9 4.3 19.2 12.7 1.3 2.2 2.2 2.1 1.6 6.5 4.3 8.5 8.0 46. 26. 17. 86. 42. 44. 71. 57. 55. 72. 73. 65. 61.5 56. 100. 69. 89. 71. Specific capacity (gpm/ft) Remarks 10 14 3 5 46 28 163 234 368 66 194 79 103 55 Before plugging 77 do 91 do 20 After plugging 23 do 55 Before plugging 22 After plugging 23 do 42 Before plugging 28 After plugging 31 Before plugging 32 do 33 do 34 do 9 After plugging 10 do 14 2 months after plugging 15 do Table 11.- Well construction and specific capacities of selected wells (continued) M - Measured; R - Reported Well Number Casing Diameter (inches) Depth (feet) Depth of well (feet) Water-bearing zones tapped Rate Drawdown (gpm) (feet) Specific capacity (gpm/ft) Remarks 34H78 34H78 34H78 34H72 34H72 33H102 33H102 33H102 33H102 33H102 33H102 01 33H104 f-' 33H104 33H104 33H104 33H104 33H104 33H104 33H115 33H118 34H134 34H133 125 545R 890R do 2,330 60. 39 After acidizing 125 545R 890R do 2,040 51. 40 do 125 545R 890R do 12 498R 950R Both 12 498R 950R do 1,940 47 .5 -- -- - -- 41 do 47 Before acidizing 108 After acidizing 12 447M 983M Both 2,000 28.6 70 January 1956 12 447M 983M do 2,300 20.3 113 July 1958 12 447M 983M do 2,440 46.0 53 September 1962 12 447M 980M do 2,280 31.5 72 January 1963 12 447M 980M do 2,250 40.0 56 May 1963 12 447M 980M do 2,150 42.0 51 October 1963 12 500R 1,000R Both 1,900 21.9 60 January 1956; SWL + 10.5 ft. 12 500R l,OOOR do 2,220 26.6 84 July 1958 12 500R l,OOOR do 1,000 85. 12 May 1962 just prior to acidizing 12 500R l,OOOR do 2,500 67.5 37 May 1962 after acidizing; SWL +0.4 ft. 12 500R l,OOOR do 2,220 60.0 37 January 1963; SWL -14.0 ft. 12 500R l,OOOR do 2,250 66. 34 May 1963; SWL -16.0 ft. 12 500R l,OOOR do 2,080 65. 32 October 1963; SWL -20.0 ft. 26 558M 947M Both 11,200 55. 204 26 560M l,OOOM Both 12,500 54 . 232 12 515M 940M Both 2,640 27.1 97 10 -- 800R Upper 750 20.6 36 1 All of upper zone and probably only part of lower zone . 2 12" casing 0-198 ft. top 8" casing 191ft. 3 80' of 18" casing at top of well. 4 40' of 18" casing at top of well. 5 105' of 20" casing above 12" casing. capacity of well 33H104 (Allied Chemical Corp. 4) from 60 gpm per ft in January 1956 to 12 gpm per ft in May 1962. After the well was acidized in May 1962, the specific capacity increased to 37 gpm per ft because the acid dissolved the small particles of limestone and secondary calcium carbonate in the solution openings tapped by the well. Figure 26 shows the decrease in the sp cific capacity of well 34H27 (Her ules Powder Co. O) caus d by plugging it at a d pth of 890 feet to isolat brac ldsb water. Immediately after plugging, the sp cific capacity decreas d from 33 gpm per ft to 9 r 10 gpm per fL. Two months after plugging, the specifi capacity increased 14 to 15 gpm per ft, probably becaus the upper water -bearing zon was Laxed more than before plugging and tb increased velociti s dean d out some o"f the accumulated loose material and opened up new waterbearing zones. The well was then acidized and the specific capacity increased to about 40 gpm per ft, which is greater than it had been before plugging. F igure 26 also shows that specific capacity decreased slightly as the ):ate of pumping increased , b cause the friction bead loss in reased about proportionally with the velocity. The specific capacity of well 34H73 (Hercules Powder Co. J) {Table 11) decreas d from 91 t 77 to 55 gpm per ft as the rat of pumping increas d from 1,550 to 2,010 to 2 530 gpm. There was less friction loss proportionally for 1 550 gpm than for 2 530 gpm flowing thr0ugh a 12-inch casing. QUALITY OF WATER The quality of ground water is determin ed principally by th rock type of the aquifer. Calcium carbonate rocks (limeston s) yield water that con- tains principally calcium and bicarbonate; calcium magnesium carbonat ocks (dolomites) yield wat r that. contains both calcium and rnagn sium as well as bicarbonate. Hydrated calcium sulfate (gypsum) is probably the chief source of sulfate in water in the Brunswick area, although minor amounts of pyrite are present in the rock. Sodium chloride (table salt) is the most abundant mineral present in sea water and the presence of abnormal amounts of sodium and chloride in ground water pumped from aquifers near coastal areas is often indicative of lateral sea-water encroachment into the aquifer from the area of the subsea outcrop. There are other sources of chloride contamination. If connate or unflushed salt water is present in rocks that are hydrologically connected to fresh-water-bearing aquifers by drillholes, or through leaky confining beds or fault zones, it can invade the fresh-water aquifers. The sources of mineral constituents in ground water and th recommended limits of particular constituents are de cribed in many publications, including U. S. Geological Suxvey Water-Supply Paper 1473, second edition, 'Study and Interpretation of the Chemical Characteristics of Natural Water," by John D. Hem (1970). The recommended limits placed on some of the more common constituents by the U. S. Public Health Service (1962) are given below: Constituent Chloride (Cl) *Fluoride (F) Iron (Fe) Manganese (Mn) Sulfate (S04) Dissolved solids Recommended limit (mg/1) 250 0.7- 1.2 0.3 0.05 250 500 *Lower and upper limits for average maximum daily air temperature range from 63.9 to 70.6F. Of special interest to residents of Glynn County is the fluoride content of ground water. According to "Drinking Water Standards," U. S. Public Health Service (1962, p. 41-42), "Fluoride in drinking water will prevent dental caries (cavities). When the concentration is optimum, no ill effects will result and caries rates will be 60-65 percent below the rates in communities with little or no fluoride." The amount of fluoride recommended in a wat r supply is based upon the annual average of maximum daily air temperature-the hotter the weather, the more liquid (water) ingest d. Th average annual temperature at Brunswick is rep rted by the U. S. Weather Bureau to be 69.2 F (v. 68, no. 13, p. 179), thus the annual average maximum temperature would be slightly greater and require a .somewhat lower fluoride content, b ecause it is assum d a greater amount of water would be ingested. For an annual average maximum t mperatur rang of 63.9 to 70.6 F the optimum amount of fluoride r comm nded is 0 .9 rng/1, with 0.7 mg/1 the lower and 1.2 nig/l the upper Limits. The average natural fluorid e content of 19 samples of ground water from wells in Glynn County tapping intervals from 310 to 1,060 feet was 0.6 mg/l. The average natural fluorid content of water samples .from the city w Us was 0.7 mgfl and ranged from 0.5 to 0.9 mg/1. Thus, the Brunswick water upply has about the recommended lower limit of fluoride in its water upply and probably provides sufficient fluoride for a low dental caries rate. The native ground water in the principal artesian aquifer is of the calcium bicarbonate type, very hard, alkaline, and has a low chloride content. Because few analyses were available for the period prior to 1959, a standard or "average" water was 52 - 0aw.:.:. 50 z(/) 0 40 _J ..JI<10 ~0 z LL. 30 -a: >-="~ 1--w ~(.:):1:>- 20 <(.l)zi 0 I 0 LL. G w & 0 0 I I 1tter plug~ing and ~cidizing 34H78 (0) I Before plugging a --o h 0.., 2 months after plugging 0.....0 ~--o After plugging I I I I 1000 2000 YIELD, IN GALLONS PER MINUTE 3000 Figure 26. Change in specific capacity when well 34H78 was plugged and acidized . 53 calculated (Wait, 1962, p. 24) using 19 selected analyses believed to be r presentative of water from the principal artesian aquifer. The average water had 23 mg/1 chloride, 204 mgjl h.ardness, and 326 mg/1 dissolved solids. This analysis is used as a standard to compare with other chemical analyses to determine if the aquifer has been in vaded by more saline water. Throughout the report the chemical analyses are referred to as ' complet " or "partial analyses. The term complete analysis refers to one made by the Geological Survey; partial analysis refers to one in which only chlmide hardness, conductivity, or total solids were determined. Unless otherwise noted, all partial chemical analyses were mad by the Hercules Powder Co. Chloride values shown in graphs for wells at Brunswick Pulp and Paper Co. and Allied Chemical Corp. were determined in their respective laboratories. Table 12 lists all complete analyses made during this investigation. The partial analyses are too voluminous to include but are used in graphs. CHLORIDE CONTENT OF WATER IN WELL FIELDS CITY OF BRUNSWICK The chlotide content of water from each of Brunswick's municipal wells differs with location, depth, and proximity to contaminated wells. Well 34H120 (City of Brunswick, F Street) is used only to supply heavy demands. Its chloride content has varied from 53 mg/1 in February 1960 to as much as 260 mg/1 in August 1964, and was 170 mg/l in October 1964. Although the chloride content varies considerably, it is within tolerable limits but is slowly increasing. The chloride content of water from well 34H134 (City of Brunswick, Brunswick Villa) has varied from 20 mg/1 in January 1958 to 30 mg/1 in January 1962 and was 30 .mg/1 in October 1964. The chloride content of water from well 34H94 (City of Brunswick, South Shipyards) has varied from a low of 22 mg/1 in September 1960 to a high of 60 mg/1 in August 1964 and was 54 mgjl in October 1964. Tllis well is probably being contaminated by well 34Gl (Babcock and Wilcox Co.), as will be explained in a later section. The chloride content of water from well 34H25 (Glynco Annex) has varied from 15 mg/1 in September 1960 to a high of 36 mg/1 in January 1962. It supplied only the Glynco Annex and Fairway Oaks subdivision, and in 1965 was not yet onnected to the existing distribution system. HERCULES POWDER CO. The chloride content of water from wells more than about 1,000 feet deep at Hercules Powder Co. has continued to increase since 1950. A rapid increase in chloride occurred in lat 1962 after the centrifugal pumps were replaced by vertical turbine pumps and after Brunswick Pulp and Paper Co. incr ased their pumpage by 36.7 mgd. The turbin pumps withdrew more water than did the centrifugal pumps, probably from the lower waterbearing zone. The plant demand was supplied in 1965 mainly from seven wells with two pumping intermittently on demand, whereas 11 wells had previously been used. The increase in chloride content of water from the wells is partly caused by lowering of water levels in the upper water-bearing zone, creating a greater head difference between it and the brackishwater zone below 1,050 feet. Most of the wells at Hercules -powder Co. were originally drilled too deep so that they partly or completely penetrated the confining unit separating the aquifer from the underlying brackish-water zone. Figur 27 shows the chloride con tent of water from wells 34H7 3 (J) and 34H78 (0) for 1950 and 1958 t~ough 1964. These two wells were plugged back to 890 feet to eliminate the chloride contamination and as a result, the chloride content of water dropped from 700 mg/1 in (J) and 800 mg/1 in (0) to about 30 mg/1, or approximately normal chloride content. Well 34B70 (F) was plugged back to 778 feet in March 1964 and th chloride content dropped from 525 mg/1 to 82 mg/1. Well 34H71 (H) was plugged back to 890 feet in May 1964 and the chloride content of water dropped from 900 mg/1 to 30 mg/1. The chloride content of water from wells that were plugged has remained low indicating no lateral movement of brackish water, thus no contours are shown on Figures 35 and 36. However, the chloride content of water from unplugged well 34H79 (P) has increased from 59 mg/1 in January 1963 to 170 mg/1 in January 1965. Well 34H75 (L) , also unplugged, has increased in chloride coptent from 33 mg/1 .in January 1963 to 55 mgfl in January 1965. It is apparent from these results that plugging, if properly done, is an effective means of reducing the chloride content of water from wells that have been drilled too deep and which penetrate the highchloride zone. BRUNSWICK PULP AND PAPER CO. The chloride content of water from wells at 54 ' 800 I I" I I a:: ~ 700 _.J wa:: a.. 600 CJ) ~ a<:t: ~ 500 _.J -_.J ~ -2 400 c.n t-!" 34~ c.n w 2 Intervol 54i 1-300 2 u 0 -w 0 200 0:: 0 _.J uI 100 34H78(0) ~-- Interval 545-1014 ft Plugged to 890 teet ' ' ' March 1964 1 --.1 August 1964 I I I 0 J _LL_ll I 1950 1958 1959 1960 1961 1962 1963 1964 Figure 27. Chloride content of water from Wl:'lls 34H73 (J) and 34H78 (0) at Hercult>s Powder Co., 1950-64. Brunswick Pulp and Paper Co. has varied only slightly since November 1958, ex ept that from wells 33H113 (6) and 33Hll8 (11 . Both hav shown increases of about 100 percent sine January 1963 (see Fig. 28) . W ll 33H113 increased from 30 .mg/1 on January 31, 1958 to 59 mg/1 on December 14, 1964 well 33Hl18 (11) increased from 31 mg/J November 11 1962, when it was put into service, to 65 mg/1 December 1, 1964. The chloride content of water from well 33H108 (1) also has increased but the increase did not begin until May 1964, mar than a year after th pumping was increased, and may be due to a leaking casing. This well was previously r paired Wait, 1965, table 4) and may be leaking again. Well 33H115 (8) has shown a slow continuous increase in chloride content since 1961. Isochlors drawn of the well field and surrounding wells for August 1962 ranged from 20 to 30 mg/1 and ran more or less northerly across the well field (see Fig. 35 ). Isochlors for November 1 B64 ranged from 20 to 60 mg/1 chiefly because of the change in chloride content of wells 33Hl13 (6) and 33Hl18 (11) and data from wells in the area east of the well field. The change in chloride values suggests movement of chloride water from the Brunswick Peninsula northwestward into that well field. ALLIED CHEMICAL CORP. The chloride content of water from the five wells at Allied Chemical Corp. has shown no increase between 1958 and 1964. The chloride content ranged from 16 to 20 mg/1 in May 1958 and 16 to 17 mg/1 in December 1964 (Fig. 29). A complete chemical analysis made of water from well 33H103 (3) shows it to be an average native water-very hard calcium bicarbonate-type water, low in chloride and with a moderate amount of dissolved solids (Table 12). CHLORIDE CONTENT OF WATER FROM TEST WELLS WELL 34H132 (TEST WELL 2) Well 34H132 (test well 2) has three samphng points. Point 1 (540 to 920 feet) is the op n hole part of the well and is the normally fresh-wat r zone. Point 2 (950 to 1 003 feet) is in the lower fresh-water zone and point 3 (1,053 to 1 ,103 feet) is in the brackish-water zone. All thr e are sepa rated by cement plugs and sampled by l'h inch pipes. Figure 30 shows the chloride values from t he three points for the period 1962 through 1964. The chloride content of water from point 1 has ranged from slightly more than 150 mg/1 in early 1962 to less than 50 mg/1 in mid-1963, and remained more or less stable until early 1964. A slight increase o curred from early to mid-1964, after which the chloride cant nt increased rapidly to nearly 140 mgjl. The incr a in chloride at point 1 during later 1964 may have been due to overflow of brackish water from point 3 into the well. The chloride content of water from point 2 has remained nearly stable and is less than 40 mg/l. Point 3 has shown several large variations and an overall increase in chlorid content apparently related to th towering of pr ssure in overlying formations. As the pressure declin s in the overlying fr shwater zone, th h d difference becomes greater and upwa:ra movement of high-chloride water is more rapid. The decrease in chloride content of points 1 and 2 in early 1962 may be the result of flushing out of high-chloride water recharged to those zones during the long construction period, or to sampling techniques. Samples were obtained by free flow at rates of less than 10 gpm for periods of 1 to 37 days until February 1963, after which samples were taken by pumping the wells 1 hour at about 60 gpm. WELL 34H337 (TEST WELL 5) Packer tests w re mad ir w 11 34H337 ( est well 5 about every 100 f t in reased depth to obtain water samples and wai r pressur measurements from restri ted zones in the aquifer. Complete and partial chemical analyses were made of the water samples from these zones. In addition, airlift reverse circulation samples were taken at about 20 foot intervals during drilling to a depth of about 1,220 feet, after which bailed samples were collected. All were analyzed for chloride and hardness. The chloride . nd hardness values from the partial chemical analyses of water from the packed intervals are usually within about 10 percent of the values from complete analyses. The hardness and chloride values from the complete analyses are shown as bars on Figure 31 and the partial analyses are shoWn as circles connected by a line. The chloride content was 18 mg/1 and the hardness was 208 mg{l in the sample from a sand above the principal artesian aquifer in the interval 502 to 522 feet. Water-level measurements and chemical quality data indicate this sand zone is hydrologically separated r m the limestone of the principal artesian aquifer. From 567 to 1,300 feet, the chen1ical analyses show the water is high in chloride content, and the pressure measurements of the packed intervals (Fig. 13) show little variation with depth, indicating more or less free vertical 56 ~] ::3~~:~~:(~)~:1::::::~ ~30 t::3~~:~::~~~~~:::::;1::;;;~ ~ 10 ~ w L> 800 ~vo:xv-: ~ a:: ::> If) ~~ OQOOC 0z 900 ct .J 3: 9w 1000 III w1w- lL. No sample packe r split ~:: <% .'1,, ~ } ~ ~ 0 >- Ll "/ ~-- - o-- - ~ -- - - "o. ' '0- , _ .;-.-o - - - oc:::::: t-:::::,-.: - 1-- := .:~ -I- -E 0 0 Ll -E 0 ~ "0 ~- 0 Ll a"(l'). E 0 (/) EXPLANAT I ON ~ - Chloride content D Hardness as CoC0 3 0 1-- Boiled or o~rl1f! reverse-c~rculotoo samples Partial chem1col analysis from I== Total depth of well 1503 feet packed 1nterval J 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 CHLORIDE CONTENT AND HARDNESS, IN MILLIGRAMS PER LITER Figure 31. Chloride content and hardness of water from well 34H337 (test well 5 ). 60 circulation of water in that interval. The hard, dense, cherty. dolomitic confining bed that was present in well 34H132 (test well 2) (Wait, 1965) and in the wells in the Hercules Powder Co. well field was not present in test well 5. Instead, the dolomitic zone consisted of rhombic crystals of dolomite with some interlayered porous white limestone. The crystalline dolomite is very porous and allows upward movement of the chloride water usually confined in the interval 1,030 to 1,400 feet. Below 1,360 feet the water was fresh, containing only 64 mg/1 chloride at 1,360 feet (bailed sample) to a low of 14 mg/1 chloride at 1,487 to 1,503 feet (packer test). Many of the samples were collected by bailing, which may account for the variation in chloride content shown in Figure 31. chloride, respectively, in May 1964. Figure 32 shows the change in chloride content of water from the four test wells. The first water samples collected from test wells 6 and 7 were higher in chloride content than subsequent samples. This was because water from test wells 3 and 4 was used for drilling the newer wells and as a consequence, slightly contaminated test wells 6 and 7. The graph shows the chloride content of water from the lower water-bearing zone is about three times that of the upper water-bearing zone and indicates separation of the zones. Further evidence of the separation of the water-bearing zones was obtained when test well 6 was pumped at the rate of about 300 gpm without causing any change in the static water level in test well 3, about 10 feet distant. WELLS 33H127 (TEST WELL 3), 33H133 (TEST WELL 6), 34H334 (TEST WELL 4), and 34H344 (TEST WELL 7) Wells 33H127 (test well 3) and 34H334 (test well 4) tap the lower water-bearing zone, and 33H133 (test well 6) and 34H344 (test well 7) tap the upper water-bearing zone. Test wells 3 and 6 are 0.85 mile east of the center of the cone of depression; wells 4 and 7 are south of Hercules Powder Co ., at Edo Miller Park . During the drilling of test wells 3 and 4 and after the casing had been cemented in place, water samples were taken from near the bottom of the open hole by pumping from the drill rods with a centrifugal pump. The chloride content of water from test well 3 was 31 mg/1 from 823 to 842 feet, 44 mg/1 from 880 to 902 feet, and 188 mg/1 from 982 to 1,002 feet. The high-chloride water occurred beneath a hard dolomite bed between 980 and 990 feet. The well was cemented back to 952 feet to seal off the chloride water and then yielded water with a chloride content of 62 mg/1 on February 2, 1963. By May 13, 1964 the chloride content had increased to 113 mg/1, indicating upward movement of chloride water through an ineffective plug or lateral movement of high-chloride water toward Brunswick Pulp and Paper Co. At test well 4, the drilling was stopped at a depth of 980 feet to prevent penetrating the chloride zone. Water samples obtained at test well 4 had 98 mg/1 chloride at 880 to 900 feet and 52 mg/1 chloride at 960 to 980 feet. When completed to 980 feet, the well flowed water with a chloride content of 45 mg/1. Test wells 6 and 7 tapped only the upper waterbearing zone from about 500 to 800 feet. Water samples from these two wells had 56 and 15 mg/1 EXPLORATION OF \\'ELL 3..tG1 (BABCOCK AND \\'ILCOX CO.) \\'ell 34G1 (Babcock and \\'ilcox Co.) was explored in May 1964 and current-meter traverses were made with the well flowing and closed in. The flow varied from 1 ,..tOO gpm at the start to 1,270 gpm at the end of the test: the change in flow rate was caused by drawdown and by the outgoing tide. \\'ater-bearing zones were determined by data from current-meter traverses. The raw current-meter data was adjusted to a constant hole size of 12 inches. Figure 33 shows the electric and gamma-ray logs and the flowing and nonflowing current-meter traverses of the well. The current-meter traverse made while the well was flowing was used to determine the water-bearing zones. \\'ater samples were taken of the free flow and by pumping through a pipe set at selected depths. The samples are regarded as composite samples of the water from the bottom of the sampling pipe to the bottom of the well. The following table gives the chloride values obtained. Depth interval (feet) 580-1,006 600-1,006 660-1,006 720-1,006 970-1,006 Chloride content of water (mg/1) 180 177 221 248 446 Sampling technique Free flow Pumped through pipe Pumped through pipe Pumped through pipe Pumped through pipe The current-meter traverse with the well closed in shows that water containing at least 446 mg/1 chloride moves upward from the interval 976 to 982 feet and into the water-bearing zone between 61 aw:: 100 I- _j aw:: Cl. 80 (f) ~ <( a:: 60 (.9 _j _j ~ 40 2 r:- w 2 I2 0 (.) w a 100 a:: 0 _j :I: (.) 80 I ntervol 823-952 ft 33HI27 (TW3) Interva l 60 802-980 ff 34H334 (TW4) 40 I ntervol 520-790 ft 33HI33 (TW 6) 1962 1963 1964 Figure 32. Chloride content of water from wells 33H127 and 133, and 34H334 and 344. 62 ~ GR .<.:,?, I ~' ', > ) <.:' ' ' ' ' \\ (, ~~---:..~.....-- / -- l~ \ \ ' ' .. ('-_-_-_-:..-::-:.-:. -.... ( :-"':. 0 EXPLANATION 100 m 20% Water-bearing zone Number ind i cotes percent of water well produces from each zone . 200 GR Gamma-radiation curve R Resistivity curve 300 S P. Spontaneous-potential curve 400 I l 15 12- inch casing __ Do >I.. 10 v / 0 5 0~ / \ IS , inch 'Jsnq ~ 1500 :z:> :1000 w 0.. i5Ul 500 / ~ olL ~ v / 0 50 100 150 200 REVOLUTIONS PER MINUTE CALIBRATION OF CURRENT METER p-rTop at 12-mch casing 80 feet Average of 5 reodmgs ~ in 12-inch casing was 163 rpm en VJ ....?/- --! i i ! f I ' :. > I I Well flow,ngr-- ~ traverse show1ng nternol flaw I ~~"'~ rJ>- 5? , t Bottom of 12-inch casing SBO f e e t - - '- ..d"' 246 0 20 40 60 80 100 120 140 160 180 REVOLUTIONS PER MINUTE Figure 33. ElectriL: and gamma radiation logs, L:Urrent meter traverses and water-hearing zones for well 34Gl (Bahcock and Wilcox) . ol 34H94 34GI 34G2 - - I 200 - - - / Casing --._ - 40o' - - t- - ~ 5751 soo' O.PPROXI MATE 0; TOP XX xxxx OF ~ AQUIFER ~ , VL/IXXXX.. eoo' 1- ,___ !- 1000I , , . ..... ..... ..... /// /// " '//////////, t t '--- - t t - J -~"""""""' ' '""'-"''\."-'\..'\..'\..'\..'\..'\..'\..'\..'\...'\.. EX P LANAT 0 N ~ ~ Fresh water-beari.ng zone Mixture of fresh ond brackish water Brackish water-bearing zone Figure 34. Diagram showing contamination of nearby wells by re charge through well bore of 34Gl. 64 730 and 760 feet. Figure 34 shows diagramatically how recharge of the high-chloride water occurs. The two nearby wells are being contaminated by water moving up the bore of well 34G1 and laterally to wells 34G2 (Georgia State Highway Department) and 34H94 (City of Brunswick, South Shipyards). The results of cementing other wells indicates that a cement plug placed from the bottom of well 34G1 to about 900 feet would effectively eliminate the movement of brackish water into the freshwater zones. AREA OF CHLORIDE CONTAMINATION Within the downtown part of Brunswick along the waterfront and northward is a small, more or less triangular area in which the chloride content of water ranges from about 60 to 1,000 mg/l. It extends along Oglethorpe Bay from well 34H337 (test well 5) northward to well 34H120 (F Street) and eastward as far as well 34H84 (radio station WGIG ). There are no wells close enough to determine the exact westward or southward extent of the high-chloride water. The chloride content of water from the upper water-bearing zone in this area for August 1962, is shown in Plate 1 and for December 1964, in Plate 2. During this time, the chloride content of water from the wells within the area has increased, especially near its north edge. Figure 35 is a graph showing the increase in chloride content of water from wells within the area from 1960 to 1964. Well 34Hll 0 (Lewis Crab, Inc . 4) is near the focus of contamination: the other wells are northward from it and near the north edge. Water from all the wells has gradually increased in chloride content since the beginning of record except 34Hll7 (Whorton Crab Co.), whose chloride content has remained nearly constant at about 20 ppm. This well is about 200 feet west of 34H113 (Golden Shores Seafood, Inc. 1 ), whose chloride content has increased rather steadily since May 1963. The reason for the abrupt change in chloride content in such a short distance is not known. Cavernous conditions and directional movement of water through the caverns offer a plausible explanation, but there is no supporting evidence. The chloride content of water from well34H125 (test well1) near the northern edge of the contaminated area, has increased steadily since mid-1961 and was 194 mg/1 in November 1964. The chloride content of well 34H122 (Brunswick Laundry) also has increased, but the well was not available for sampling from October 1963 until April 24, 1965, when a sample of water had 300 mg/1 chloride, indicating a continued increase. The chloride content of water from wells 34H128 (Firestone Store) and 34H129 (Glynn Cleaners) increased from 26 mg/1 in 1962 to 58 mg/1 in 1964. Although well 34H128 is one block north of well 34H129, they both have the same chloride concentration. Isochlors shown in the Brunswick Pulp and Paper Co. well field indicate a general increase in the chloride content of water there. Graphs of the chloride content of water from the wells show that the two southernmost wells, 33Hll3 (6) and 33Hll8 (11), have increased about 100 percent since early 1963. \Yater from well 33H1 08 (1) has also increased in chloride content from 19 mg/1 in March 1964 to 50 mg/1 in December 196-l. However, the increase in chloride content of water from this well may not be related to vertical movement of brackish water, for the well is reported to be 900 feet deep and does not tap the brackishwater zone. The increase in chloride content of water from wells 33H108 and 33Hll3 is believed to be caused by lateral or upward movement of brackish water into the lower water-bearing zone. None of the wells in the Allied Chemical Corp. well field, immediately north of Brunswick Pulp and Paper Co., had by 1965 shown any increase in chloride content. The shape of the isochlors in the Brunswick Pulp and Paper Co. well field and the change in chloride content of water from wells east of there indicate that water with a higher chloride content is present east and southeast of the well field, and is moving toward it. The chloride content of water from well34H132 (test well 2), point 3 (1 ,053 to 1,103 feet), had increased to more than 300 mg/1 (Fig. 30) by the end of 1964, indicating a general westward movement of the brackish-water zone. \\'ell 34H351 (Twin Oaks Drive-In) was drilled in 1964 to 760 feet and cased to about 524 feet , with -l and 3 inch casing. Water from it had a chloride content of 170 mg/1 in November 1964. lt is 0 .7 mile north of well 34H129, which had a chloride content of about 50 mg/1, and 0.5 mile south of well 34H132 (test well 2), point 1, which had a chloride content of 52 mg/1 in July 1964. The high chloride content of water from well 34H351 may reflect northward movement of chloride in a narrow band, or a situation similar to that near the focus of chloride contamination at test well 5, where the confining bed capping the brackish-water zone is ineffective. Well 34G1 (Babcock and Wilcox Co .) at the south tip of the Brunswick Peninsula was explored 65 0::: ~ 1200rr~-rroo-rrTO-rrT~_,,.,_,..,,_,..,,.~,-,.,.-,.,.,,.,.-,rr,-,.,,-rr~rro ::::i 0::: ~ 1000 ~------------+-------------+-------------4-----------~-r------------_, (f) ~ W- a~:: w ::::> -: IL..(J) I I. . I 20 -2 20 oct of plugging in W('ll 34G3 . water. The laboratory analyses show these concentrated waters contain excess calcium, magnesium, and sulfate compared to a theoretical mixture of fresh and sea water. Theoretical mixtures also were calculated using the most concentrated water from well 33G3, and native fresh water from nearby well 33H16 calculated to the chloride content of several concentrated waters. Table 14 compares these calculated mixtures to actual analyses of contaminated samples from several wells. The calculated mixtures indicate that well 33G3 does not appear to be the source of contamination. Love (1944, p. 952) found that in the Miami , Fla., area fresh water in the Tamiami Formation that was invaded by sea water had an excess of calcium and a deficien y of magne-si um . sod ium , and pot ass ium . T he excess o.f cal ci u m was a ppro ximately balanced by the d eficiency o f m agn sium, sodium , an d potassium , indicating base xcha nge. Piper and Garrett (1953 p. 1 04-109 ) also found t hat in th e Long Beach -Santa Ana , Calif., area contamin ated water usually contai ned an excess of calcium and magnesium approximately balanced by a deficiency in sodium. However, the contaminated waters in Glynn County contain an excess of calci um , magnesi um and sulfate bu t are only sli ght ly d efi cien t, if at all, .in sodium when compared t o a calculated mixtur o f native and ea wa'ter . Thus it appears t hat th p ossi ble con ta mi nant are neither sea water nor water from well 33G3. The chloride content of water from well 34H94 (City of Brunswick, South Shipyards) has increased from 28 mg/1 on August 3, 1959, to 60 mg/1 on August 6, 1964. Current-meter traverses of well 34G1, about 1,400 feet east, have shown it to be a probable source of chloride. A mixture was calculated using the analyses of wa ter fr o m well 34H94 (August 3, 19 59 ) containing 28 mg/1 chloride and water from the 970 to 1 ,006 foo t in terval in well 34G1 co ntainin g 4 66 mg/1 chloride , to the chloride conten t of a sampl e fro m 3 4H94 collected in August 1963, containing 4 0 mg/l chloride (Table I 5 ). Th e calculated mixture nearly duplicates t he August 1 963 analysis and shows that the in rease in hl oride conten t o f wa ter from well 34H94 is caused by movement through the well bore of 34G1. Table 16 gives the results of a theoretical mixture of water from weLl 33Hl27 (test well 3) using the co ntam inated water from th e interval 982 to 1 ,002 fee t from that well and the fresh water fr om the interval 8 23 to 84 2 feet ca lculated t o the chloride conte nt of a sample ta ken May 13, 1964, whi ch re presents the interval 823 to 952 f ee t . The calc ul ated mixture is n early identical to th e lay 13 sample and sh o ws tha t upward m o vemen t of water from below 982 feet is occurring. A t h oretical mixture of nat ive fresh wa t er and sea wa ter , calcula ted t o t he chloride co n tent of t h con tam inated water from the 982 to 1 ,002 foot interval from well 33H127, contains an excess of 6.77 milli-equivalents per liter and shows that the source of water contaminating the lower water-bearing zone is not a simple sea-water-fresh-water mixture. LATERAL SEA-WATER ENCROACHI\IENT As of 1965, there was no evidence of lateral seawater encroachment in Glynn County. lf sea water were moving laterally through the aquifer from a submarine outcrop seaward from Glynn County. it would be detected first in wells on the sea islands. Well 34H42 on Sea lsla11d is 1.0-l 2 fePt deep and yields water with a chloride content of 29 mg/1. A sample from 1 ,0 34-1.0 -.t- 2 fe e t had 30 m gj l chloride. \\'ell 34H160. on the so uth end of St. Simons Island, is 1,050 feet deep and yields water with a chloride content of 2--l mg/1. Other wells on St. Simons and Jekyll Islands yield water with a chloride content ranging from 20 to 30 mg/1 and none have shown increases in chloride concentration. The offshore distance to brackish water in the principal artesian aquifer is unknown. However, the rate of movement of a particle of water in the aquifer at a point 20 miles offshore can be determined by the formula for the velocity of ground water, given previously . The permeability o,f the upper zo ne is t akPn as a bout 8 ,200 gpd per ft and the porosity is 30 p n :en l. T he a pproximate head at 10 to 20 mil es offshore is interpolated from a paten tiorn e tric ma p (Callahan , 1964, Pl. 1) as 33 fee t and 27 fe t a bove mean sea level in 1960. These head measurements and data from the 1964 potentiometric map of Glynn County (Fig. 12) were adjusted to 10 years after the 1962 pumpage increase from 93 mgd to 1 ~2 mgd. The data show the potentiom~tric surface is above sea level and forms a ground-water divide of greater than 25 foot head above sea level .between t he existin g center of pumpa ge and 10 mtles offshore. A similar divide in the poten t iom etric surface (a bove sea levE' l) would e xist wh en the heads were adjusted for drawd o wn 10 years after an increase to 200 mgd . A ground-water divide of greater t han 25 foot head would probably prevent sea water , if present offshore in the principal artesian aquifer above a depth of 1 ,000 feet , from moving laterally toward the center of pumping any closer than the position of the divide. The gradient created by pumping 500 mgd from a single hypo- 72 Table 14.-Calculated mixtures of contaminated water from well 33G3 (Massey oil test) and fresh water from well 33H16 (Satilla Shores Subdivision) to the chloride content of contaminated water from several wells. Depth Milliequivalents per liter Well Interval (feet) Ca Mg Na K HC03 so 4 Cl Total F Excess 33H16 33G3 580-780 640- ? 2.45 33.88 1.97 39.32 0.61 1 9 0 .1 0 0.05 3.09 2.49 2.12 0.39 2.47 44.35 212 .99 0.02 .10 Contaminated water 34H337 34H337 987-1,007 9.58 10.42 18.27 .25 2.29 11.20 21.86 .04 1,182-1,200 5.79 5.81 7 .18 .14 2.36 7.33 9 .25 .05 33Hll7 34G1 1,873-1,903 21.26 18.43 58.29 1.48 2.46 66.21 28.21 .17 970-1,006 6.54 9.10 11.53 .15 2 .3 3 11.97 13.15 .03 -.J Cl.;) Calculated mixture of water from wells 33G3 and 33H16 to chloride content of water from: 34H337 34H337 33H117 34G1 987-1,007 5.62 5.74 19.75 .36 2.49 6.38 21.86 .04 1,182-1,200 3.76 3.53 8.51 .18 2.49 3.88 9.25 .02 1,873-1,903 7.18 8.11 25.51 .45 2.24 9.79 28.21 .53 970-1,006 4.34 4.21 11.98 .23 2.49 4.65 13 .15 .02 Excess (+) or deficiency (-) in contaminated sample compared to calculated mixture 34H337 34H337 33H117 34G1 987-1,007 1,182-1,200 1,873-1,903 -970 +3.96 +2.03 +14.08 +2.20 +4.68 +2.28 +10.32 +4.89 -1.48 1 .3 3 +32.78 -.45 -.11 -.04 +1.03 -.08 -.20 +4.82 - -.13 +3 .45 - +.22 +56.42 ,_ -.16 +7.33 - - +.01 +.03 -.36 . -.01 +11.67 +6.29 +114.49 +13.73 Table 15.-Calculated mixtures of contaminated water from 34G 1 (Babcock and Wilcox Co.) and fresh water from 34H94 (City of Brunswick, South Shipyards), August 1959 to chloride content of water from 34H94, August 1963. Milliequivalents per liter Total Well Ca Mg Na K HC03 804 Cl F Excess 34G1 (970-1,006 feet) 6.54 9.10 11.53 15 2.33 11.97 13.15 .03 34H94 (August 1959) 2.10 2.06 .87 .01 2.29 1.92 .79 .04 -.J ,;::.. 34H94 (August 1963) 2.25 2.27 1.22 .04 2.33 2.21 1.13 .04 Calculated mixtures of 34G1 and 34H94 (August 1963) 2.22 2.25 1.16 .01 2.29 2.20 1.13 .04 Excess (+) or deficiency (-) in contaminated sample compared to calculated mixture +.03 +.02 +.06 +.03 +.04 +.01 -- --- +.19 Depth (feet) Table 16.-Calculated mixtures of waters from well 33H127 (test well 3). Milliequivalents per liter Ca Mg Na K HC03 804 CI Total F Excess 823-842 (August 16, 1962) 1.90 2.30 1.00 0.07 2.00 2.02 0.87 .03 982-1,002 (August 20, 1962) 4.64 4.44 4.57 .10 2.39 5.64 5.30 .04 823-952 (May 13, 1964) 2.94 3.10 3.13 .06 2.49 3.33 3.19 .04 Calculated Mixture 3.29 3.42 2.87 .08 2.20 3.92 3.19 .06 -J c.n Excess (+) or deficiency (-) in contami- nated water (832-952 feet) compared to calculated mixture -.35 -.32 +.26 -.02 +.29 -.59 .. -.02 -0.75 Calculated mixtures of sea water and native fresh water to chloride content of 982-1,002 foot sample Excess (+) or defiaiency (-) in contaminated sample (982-1,002 feet) compared to calculated mixture 2.35 +2.29 -- 2.78 +1.66 5.13 -0.56 .12 2.36 2.28 5.30 .03 -.02 +.03 +3.36 - +.01 +6.77 thetical well near the present day center of pumpage would cause water in the aquifer 20 miles offshore to move into the center of pumpage in about 300 years. Although the concentration of chloride in the aquifer east of the shoreline is unknown, the above estimates indicate there is little chance of chloride contamination by lateral sea-water encroa hmen t under present or predicted (200 mgd) c nditions of pumpin g in Glynn County. These alculations assum no d cline in the potentiometri surfa due to increased p umpage at other localities along t h e coast . An y targ ground-water withd awals from t h prin ipal art sian aquifer elsewhere along the coast would cause regional lowering of water levels and increase the landward rate of water movement. RESIDUAL PROBLEMS AND CONTINUING INVESTIGATION The presence of high-chloride water in the principal artesian aquifer requires constant monitoring of the quality of water. Selected wells should be sam pl d frequent ly f or chloride content and maps pr pared for com parison with past data to determine t he extent of contamination and the rate of movement of the chloride body. Continued lowering of water levels will increase the bead differ n ee acr oss confining beds and hasten the upward m ovement of high chloride wat r from below 1 ,000 feet. Howe ver , no serious problems are anticipated exc pt in areas wher the confinin g bed is ineffective as in t he cit y area near well 34 H337 (test well 5). It should be recognized that similar areas may exist elsewh re in th county, but hav not as yet (1965) b en det ected. Th refore, the water sampling rogram must b e comprehensive enough to d etect changes in chlorid content of water throughout the county. Water-lev 1 measurements should be continued to determine the effect of pumping on the ground-water body, and measurements should be made of water-level recovery during industrial shutdowns to refine and extend the existing hydrologic data. Additional test drilling is needed to determine m ore xac Lly t h area of contamination in tbe city and to o btain geologic informatio n ab ut the presen ce of possi bl fault ing. Closely spaced test holes in t h e ci ty area should b drilled and logged to obtain additional geologi data. Th rate of hloride contamination of the principal artesian aquifer by brackish water might be reduc d , or even stopped, by withdrawing water from a system f r li f wells drilled into the brackish-water zone. Wells should tap the brackish- water zone from about 1,050 to 1,300 feet and the water should be pumped to waste, or used in processes where the quality is not a problem. Pumping the relief wells would lower the hydrostatic head in th brackish-water zone, thus de- ex asing t he head differen ce across the confining bed and reducing t he rat of movement of brackish water across it into the principal artesian aquifer. Figure 38 shows, diagramatically, the hydraulic equilibrium between the fresh- and brackish-water zones and the constant rate of upward movement of brackish water. If equilibrium conditions exist, upward movement of brackish water is at a constant rate to time 3, on Figure 38. When the pumping rate is increased at some arbitrary time 3, the water level in the fresh-water zone declines and increases the difference in head between the freshand brackish-water zones, upsetting the equilibrium. The increase in head difference produces an increased rate of chloride contamination nearly proportional to the head difference between the freshand brackish-water zones. This, in turn, causes a decline of the head in the brackish-water zone. The rate of head decline in the brackish-water zone will probably lag the rate of head decline in the freshwater zone until an equilibrium condition is reached at some later time, after which the rate of movement of brackish water to the aquifer should be nearly the same as before the increased pumping from the aquifer at time 3. At time 10, a relief well starts withdrawing water from the brackish-water zone causing a rapid decline of head in it and resulting in a decrease in the rate of brackish-water movement into the freshwater aquifer. With a smaller rate of recharge, the head in the fresh-water aquifer will probably decrease slightly. Additional testing and evaluation of the hydraulic properties and physical characteristics of the chloride zone and of the confining zone are necessary for the design of an effective reliefwell system. Relief wells in the vicinity of the focus of chloride contamination would be the most effective means of decreasing the head in the chloride zone. These areas should be studied carefully before any relief wells are drilled. SUMMARY AND CONCLUSIONS Glynn County is underlain by gravel, sand, and clayey silt to a depth of about 500 feet, below which are carbonates to a depth of about 2,000 feet. A clayey-silt bed of Miocene age 60 to 80 feet thick, whose top is at a depth of 160 to 180 feet, is an excellent confining bed. It separates the Pliocene (?) and Pleistocene sand and gravel from 76 8 I I I I Head in high-chloride zone -- 7 .c w 0::: ::::> 6 (/) (/) w 0a:.:.: 5 0 - 1- ~ 4 below about I050 feet ~ I t......... I - I ---- I l Head in principal 1'--- artesian aquifer Increosed pumping in principal artesian aquifer (/) 0 0::: 3I Q -.J -.J >::r-: I :\ l I I I I. 1 l Begin pumping from relief wells topping-high-chloride zone \ :\ " I I '- 2 ' I I 1-........, ......._ I I I ao:D......' 4 <~ 1...-. -I - I O.z :lw 2 : "o-w:E w>o I I ~:E 0 I \ 1"-- I a: 0 2 3 4 5 6 7 8 9 10 II 12 13 14 IS 16 17 18 TIME (t) Figure 38. Sketch of the hydrology of a hypothetical relief well system. the Miocene aquifer. Little water is pumped from the Miocene aquifer; however, yields of 200 gpm or more could be obtained from properly constructed gravel-packed, screened wells. A hard, dense limestone (Oligocene?) at the top of the principal artesian aquifer is also a confining bed with fresh water to a depth of about 1,000 feet below it. Dolomitic limestone, present from about 1,000 to 1,050 feet, is a confining bed below which brackish water is present to a depth of about 1,350 feet. There are two water-bearing zones in the limestone: one from about 500 to 760 feet and the other from about 860 to 1,000 feet. The upper water-bearing zone yields about 70 percent and the lower water-bearing zone about 30 percent of the water to wells penetrating both zones. Wells in the Brunswick Peninsula that are drilled to depths below about 1,000 feet penetrate the hard, dense dolomitic confining bed and commonly yield brackish water. The estimated pumpage in Glynn County in 1964 was 122.3 mgd, about 90 percent of which was used for industrial purposes, mostly in washing and cooling processes. Pumping in the coastal area since 1880 has caused water-level declines. In Glynn County these range from 60 to 65 feet near the center of the cone of depression and are about 35 feet on the sea islands. The transmissivity and storage coefficients have been determined by four methods: flow tests of individual wells, recovery of water levels caused by large decreases in pumpage during industrial shutdowns, the lowering of water levels caused by a 36.7 mgd increase in pumpage, and flow-net analyses of several potentiometric maps. The transmissivity ranges from about 800,000 to 1,000,000 gpd per ft in the upper zone of the principal artesian aquifer and from about 300,000 to 500,000 gpd per ft in the lower zone. The transmissivity for both zones ranges from 1,400,000 gpd per ft to 1,600,000 gpd per ft and the storage coefficient is about 0.003 for long-term drawdown. The water levels in the upper zone change as if the apparent transmissivity is 1,400,000 gpd per ft and the storage coefficient is 0.004 (for long-term pumping), when observing pumpage from both zones. The storage coefficient shows an apparent increase with time because of slow drainage of the soft limestone confining bed between the waterbearing zones and because of some local leakage from the overlying and underlying beds. The upward leakage from below about 1,050 feet locally contaminates the principal artesian aquifer with brackish water. The rate of contamination can probably be partially checked by the construction of relief wells into the brackish-water zone, and to a lesser extent by proper spacing of any future production wells. A graph (Fig. 22) shows the decline in water level at various distances, caused by an increase in pumpage of one million gallons per day, and can be used to predict water-level changes caused by increases in pumpage. A predicted potentiometric map (Fig. 24) shows that declines would range from 20 to 25 feet near the center of the cone of depression to 10 feet at the county boundaries if an additional 70 mgd is pumped from the aquifer at the assumed locations. The 70 mgd increase is not a limiting pumpage. The amount of water that can be developed in future years depends upon several factors. Widespread distribution of well fields in Glynn County will result in the least amount of drawdown and well intf'rference and will keep pumping costs lower. Development of ground water in adjoining counties, now largely undeveloped, will cause water-level declines in Glynn County and will influence the location of ground-water withdrawals in the county. A very hard magnesium-sulfate water with low chloride is present between 1.400 and 1,700 feet. It could be utilized as a source of industrial water for some processes. It could be softened and used for specialized process more cheaply than surfacewater supplies could be obtained from the Altamaha River. Additional or replacement supplies of ground water could be developed in the western part of Glynn County as well as on Colonels Island. The brackish water is entering the usually freshwater zone in the city because the confining bed that separates the fresh water and the underlying brackish water is ineffective. The brackish water obtained from well 34H351 (Twin Oaks Drive-In) may enter the aquifer under similar conditions. The mass of saline water is moving northward toward the center of the cone of depression at a rate of about 700 feet per year in the upper waterbearing zone. As the cone of depression gets deeper, the rate of movement will increase. To date (1965) there is no evidence of lateral sea-water encroachment. Data show that if withdrawal in Glynn County is increased to 200 mgd, a positive head above sea level will still exist on Jekyll and St. Simons Islands. 78 SELECTED REFERENCES Applin, P. L., 1951, Preliminary report on buried pre-Mesozoic rocks in Florida and adjacent states: U.S. Geol. Survey Circ. 91, 28 p. Applin, P. L., and Applin, E. R., 1944, Regional subsurface stratigraphy and structure of Florida and southern Georgia: Am. Assoc. Petroleum Geologists Bull., v. 28, no. 12, pp. 1673-1753. Bredehoeft, J. D., Cooper, H. H., Jr., Papadopulos, I. S., and Bennett, R. R., 1965, Seismic fluctuations in an open artesian water well in Geological Survey Research 1965: U.S. Geol. Survey Prof. Paper 525-C, p. C51-C57. Brown, J. S., 1925, A study of coastal ground water, with special reference to Connecticut: U.S. Geol. Survey Water-Supply Paper 537, 101 p. Callahan, J. T., 1964, The yield of sedimentary aquifers of the Coastal Plain, Southeast River Basins: U.S. Geol. Survey Water-Supply Paper 1669-W, 56 p. Callahan, J. T., Wait, R. L., and McCollum, M. J., 1962, Television-a new tool for the groundwater geologist: Georgia Min. Newsletter, v. 15, nos. 1-2, pp. 22-25. Collins, W. D., Lamar, W. L., and Lohr, E. W., 1935, The industrial utility of public water supplies in the United States 1932: U.S. Geol. Survey Water-Supply Paper 658,135 p. Cooke, C. W., 1943, Geology of the Coastal Plain of Georgia: U.S. Geol. Survey Bull. 941, 121 p. Cooper, H. H., Jr., and Warren, M. A., 1945, The perennial yield of artesian water in the coastal areas of Georgia and northeastern Florida: Econ. Geology, v. 40, no. 4, p. 263-282. Cooper, H. H., Jr., and Jacob, C. E., 1946, A generalized graphical method of evaluating formation constants and summarizing well-field history: Am. Geophs. Union Trans., v. 27, no. 4, p. 526-534. Cooper, H. H., Jr., Kohout, F. A., Henry, H. R., and Glover, R. E., 1964, Sea water in coastal aquifers: U.S. Geol. Survey Water-Supply Paper 1613-C, 84 p. Counts, H. B., 1958, The quality of ground water in the Hilton Head Island area, Beaufort County, South Car.olina: Georgia Min. Newsletter, v. 11, no. 2, p. 50-51. Counts H. B., and Donsky, E., 1963 , Salt-water encroachment, geology, and ground-water re- somces f Savannah area, Georgia and South Carolina: U.S. Geol. Survey Water-Supply Paper 1611, 100 p. Dall, W. H., and Harris, G. D., 1892, Correlation papers; Neocene: U.S. GeoL Survey Bull. 84, 349 p. Darby, D. G., and Hoyt, J. H., 1964, An upper Miocene fauna dredged from tidal channels of coastal Georgia: Jour. Paleontology, v. 38, no. 1, p. 67-73. Ferris, J. G., Knowles, D. B., Brown, R. H., and Stallman, R. W., 1962, Theory of aquifer tests: U.S. Geol. Survey Water-Supply Paper 1536-E, p. 69-174. Grantz, A., Plafker, G., and Kachadooxian, R., 1964, Alaska's Good Friday Earthquake, March 27, 1964, a preliminary geologic eva! uation : U.S. Geol. Survey Circ. 491, 35 p . Gregg, D. 0., 1966, An analysis of ground-water fluctuations caused by ocean tides in Glynn County, Georgia: Ground Water, v. 4, no. 3, pp. 24-32. Gutenberg, Beno, 1959, Physics of the earth's interior: New York Academic Press, 240 p. Hanshaw, B. B., Back, W., Rubin, M., and Wait, R. L., 1965, Relation of Carbon-14 concentrations to saline water contamination of coastal aquifers: Water Resources Research, v. 1, no. 1, p. 109-114. Hem, J. D., 1970, Study and interpretation of the chemical characteristics of natural water, 2nd ed.: U.S. Geol. Survey Water-Supply Paper 1473, 269 p. Herrick, S. M., 1961, Well logs of the Coastal Plain of Georgia: Georgia Geol. Survey Bull. 70, 462 p. _ _1965, A subsurface study of Pleistocene deposits in coastal Georgia: Georgia Geol. Survey Inf. Circ. 31, 8 p. Herrick, S.M., and Vorhis, R. C., 1963, Subsurface geology of the Georgia Coastal Plain: Georgia Geol. Survey Inf. Circ. 25, 80 p. Herrick, S. M., and Wait, R. L., 1955, Interim report on results of test drilling in the Savannah area, Georgia and South Carolina: U.S. Geol. Survey open-file report, 48 p. 79 __1965, Subsurface stratigraphy of Coastal Georgia and South Carolina [abs.]: Am. Assoc. Petroleum Geologists Bull., v. 49, no. 3, p. 344. Hoyt, J ., and Henry, V. J., 1962, Geologic history and dev lopment of barrier islands in the vicinity of Sapelo lsland, Ga. [abs.]: Geol. Soc. America Bull. v. 73 p. 11 . Hurst, V. J., 1960, Oil tests in Georgia: Georgia Geol. Survey Inf. Circ. 19, 14 p. Johnston, J. E., Trumbull, J., and Eaton, G. P., 1960, The petroleum potential of the emerged and submerged Atlantic Coastal Plain. of the United States: Georgia Min. Newsletter, v. 13, no. 2, p. 66-73. Lamar, W. L., 1942, Industrial quality of public water supplies in Georgia, 1940: U.S. Geol. Survey Water-Supply Paper 912, 83 p. Lohr, E. W., and Love , S. K. 19M, The industrial utility of publi wat r supplies in the United States, 1952, Pt. 1, State east of the Mississippi River: U.S. Geol. uxvey Water-Supply Pap r 1299, 639 p. Love, S. K., 1945, Cation-exchange in ground water contaminated with sea water near Miami, Florida: Am. Geophys. Union Trans., Part VI, Twentyfifth Annual Meeting, June 1944, p. 951-959. McCallie, S. W. , 1898, Artesian-well system of Georgia: Georgia Geol. Survey Bull. 7, 214 p. __1908, Underground waters of Georgia: Georgia Geol. Survey Bull. 15, 370 p. McCollum, M. J., 1964, Salt-water movement in the principal artesian aquifer of the Savannah area, Georgia and South Carolina: Ground Water, . v. 2, no. 4, p. 4-8. McCollum, M. J ., and Counts, H. B., 1964, Relation of salt-water encroachment to the major aquifer zones, Savannah area, Georgia and South Carolina: U.S. Geol Survey Water-Supply Paper 1613-D, 26 p. MacNeil, F. S., 1950, Pleistocene shore lines in Florida and Georgia: U.S. Geol. Survey Prof. Paper 221-F, p. 95-107. Meinzer, 0. E., 1923, The occurrence of ground water in the United States, with a discussion of principles: U.S. Geol. Survey Water-Supply Paper 489, 321 p. Mussey, 0. D., 1955, Water requirements of the pulp and paper industry: U.S. Geol. Survey Water-Supply Paper 1330-A, 71 p. Neiheisel, J., 1962, Heavy-mineral investigation of Recent and Pleistocene sands of lower Coastal Plain of Georgia: Geol. Soc. America Bull., v. 73, p. 365-374. Piper, A. M., and Garrett, A. A., and others, 1953, Native and contaminated ground waters in the Long Beach-Santa Ana area, California: U.S. Geol. Survey Water-Supply Paper 1136, 320 p. Smith, W. 0., and Sayre, A. N., 1964, Turbulence in ground-water flow: U.S. Geol. Survey Prof. Paper 402-E, 9 p. Stephenson, L. \V., and Veatch, J. 0., 1915, Underground waters of the Coastal Plain of Georgia, and a discussion of the quality of the waters by R. B. Dole: U.S. Geol. Survey \\"ater-Supply Paper 341, 539 p. Stewart, J. W., 1960, Relation of salty ground water to fresh artesian water in the Brunswick area, Glynn County, Georgia: Georgia Geol. Survey Inf. Circ. 20, 42 p. Stewart, J. W., and Counts, H. B., 1958, Decline of artesian pressure in the Coastal Plain of Georgia, northeastern Florida, and southeastern South Carolina: Georgia !\lin. Newsletter, v. 11, no. 1, p. 25-31. Stewart, J. W., and Croft, M. G., 1960, Groundwater withdrawals and decline of artesian pressures in the coastal counties of Georgia: Georgia Min. Newsletter, v. 13, no. 2, p. 84-93. Strlngfi ld V. T. , Warren, M.A. a.nd oop r, H. H., Jr .. 1941, Artesian water in lh oa laJ area of eorgia and northeastern Florida : Ec n. G logy, v. 36, no. 7 . p. 6. 8-711 . Theis, . V., 1935, Re lation b lwe n Lhe lowering of th piezometric surface and t.he rat.e and duration of dis harge of a we ll using ground-water stmage: Am. Geophy . Union Trans., pt. 2, p. 519-524 ; dupl. as U.S. Geol. Survey Ground \Vater Note 5, 1952. Thomson, M. T. Herrick, S. M., Brown E. and oth r , 1956, The availability and use of water in G orgia: G orgia Geol. Survey Bull. 65, 316 p. 80 Wait, R. L., 1962, Interim report on test drilling and water sampling in the Brunswick area, Glynn County, Ga.: Georgia Geol. Survey lnf. Circ. 23, 46 p. Wait, R. L., 1965, Geology and occurrence of fresh and brackish ground water in Glynn County, Georgia: U.S. Geol. Survey Water-Supply Paper 1613-E, p. E1-E94. Wait, R. L., and Callahan, J. T., 1965, Relations of fresh and salty ground water along the southeastern U.S. Atlantic Coast: Ground Water, v. 3, no. 4, p. 3-17. Wait, R. L., and McCollum, M. J., 1963, Contamination of fresh water aquifers through an unplugged oil test well in Glynn County, Georgia: Georgia Min . Newsletter, vol. 16, nos. 3-4, p. 7480. Warren, M.A., 1944, Artesian water in southeastern Georgia, with special reference to the coastal area: Georgia Geol. Survey Bull. 49, 140 p. and Bull. 49-A, Well records, 83 p. 81 Appendix A.-New and previously used well numbers in Glynn County, grouped by topographic map quadrangle. This Report WSP 1613-E Bulletin 49-A 33G1 33G2 33G3 33G4 33K1 33K2 33K3 33K4 34G1 34G2 34G3 34G4 34G5 34G6 34G7 34G8 34G9 34G10 34G11 34G12 34G13 34G14 34G15 34G16 34G17 34G18 34G19 34G20 34G21 34G22 34G23 34G24 34G25 34G26 34G27 34G28 34G29 34G30 33G Dover Bluff 1/24,000 H-20 H-9 H-8 H-19 33K Everett City 1/62,500 A-12 A-6 114 A-7 113 A-11 34G Jekyll Island 1/24,000 J-36 209 J-212 J-53 J-226 J-86 J-54 J-57 J-87 J-62 J-56 170 J-55 J-58 169 J-59 J-60 J-61 J-63 J-64 J-65 J-66 171 J-67 J-72 171 J-224 J-225 J-68 J-71 166 J-69 167 J-70 168 J-76 J-232 J-233 This Report WSP 1613-E Bulletin 49-A 32H 1 32H2 32H3 32H4 32H5 32H6 32H7 32H8 32H9 32H10 32H 11 32H12 32H13 32H14 32H15 32H16 32H17 32H18 32H19 32H20 32H21 32H22 32H23 32H24 32H25 32H26 32H27 32H28 32H29 32H30 32H31 32H32 32H33 32H Bladen 1/ 24,000 F -6 F -21 F-5 F-4 F-7 F-19 E-9 E-10 E-132 F-22 F-18 F-17 F - 16 F-8 F -11 F-9 F - 12 F-13 F-10 G-1 G-2 G-5 G-3 G-4 E-72 E-75 E-112 E -111 E-113 E-114 132 131 -B 131 -A 131 130 188 189 190 187 186 85 33H1 33H2 33H3 33H4 33H5 33H6 33H7 33H8 33H Brunswick West 1/24,000 E-108 H-21 H-14 H-26 H-13 H-7 87 H-24 H-6 84 83 Appendix A.-New and previously used well numbers in Glynn County, grouped by topographic map quadrangle-Continued This Report WSP 1613-E Bulletin 49-A This Report WSP 1613-E Bulletin 49-A 33H Brunswick West 1/24,000 (Contin.) 33H9 33H10 33H 11 33H12 33H13 33H14 33H15 33H16 33H17 33H18 33H19 33H20 33H21 33H22 33H23 33H24 33H25 33H26 33H27 33H28 33H29 33H30 33H31 33H32 33H33 33H34 33H35 33H36 33H37 33H38 33H39 33H40 33H41 33H42 33H43 33H44 33H45 33H46 33H47 33H48 33H49 33H50 33H51 33H52 H-23 H-3 H-18 H-15 H-16 H-4 H-5 H-12 H-1 0 H-11 H-22 H-1 H-2 E-135 E-1 09 E-68 E-70 E-69 E-66 E-67 E-65 E-64 E-74 E-61 E-62 E-63 E-115 E-83 E-84 E 142 E-89 E-90 E-88 E-133 E-122 E-87 E-91 E-86 E-121 E-79 E-20 E-1 01 E-31 E-77 138 136 137 88 89 11 97 119 118 120 11 Oa 33H Brunswick West 1/24,000 (Contin.) 33H53 E-30 60 33H54 E-1 07 33H55 E-138 33H56 E-23 63 33H57 E-24 62 33H58 E-139 33H59 E-21 19 33H60 E-29 61 33H61 E-26 9 33H62 E-27 33H63 E28 33H64 E78 33H65 E-76 33H66 E-25 59 33H67 E-99 33H68 E-100 33H69 E-97 33H70 E-98 33H71 E-96 33H72 E-32 21 33H73 E-95 33H74 E-34 17 33H75 E-35 181 33H76 E-33 18 33H77 E-39 58 33H78 E-81 33H79 E-82 33H80 E-40 33H81 E-120 33H82 E-119 33H83 E-42 185 33H84 E-37 184 33H85 E-41 33H86 E38 33H87 E-46 33H88 E-80 33H89 E-45 10 33H90 E-44 20 33H91 E-118 33H92 E-43 16 33H93 E-85 33H94 E-92 33H95 E-140 33H96 E-93 84 Appendix A.-New and previously used well numbers in Glynn County, grouped by topographic map quadrangle. This Report WSP 1613-E Bulletin 49-A This Report WSP 1613-E Bulletin 49-A 33H Brunswick West 1/24,000 (Cantin .) 33H97 E-94 33H98 E-48 208 33H99 E-73 33H100 E-47 33H 101 E-49 1 33H102 E-50 2 33H103 E-51 3 33H104 E-52 4 33H105 E -11 33H106 E-1 05 33H107 E-54 25 33H1 08 E-55 22 33H 109 E-56 23 33H 110 E-53 24 33H 111 E-1 02 33H 112 E-1 03 33H 113 E-25 33H 114 E-116 33H 115 E-117 33H 116 E-134 33H 117 E-137 33H 118 E-106 33H 119 E-57 192 33H120 E-59 33H 121 E-58 33H 122 E-60 207 33H 123 E-136 33H124 E-13 33H 125 E-14 134 33H126 E-71 86 33H 127 (test well3) E-143 33H 128 E-144 33H129 E-145 33H130 E-146 33H 131 E-148 33H 132 33H 133 (test well6) E-149 33H134 34H Brunswick East 1/24,000 34H1 D-22 98 34H Brunswick East 1/ 24,000 (Cantin .) 34H2 D-104 34H3 D-24 34H4 D-175 34H5 D-103 34H6 D-25 95 34H7 D-23 96 34H8 D-174 34H9 D -26 94 34H10 D-172 34H11 D -29 93 34H12 D -15 106 34H13 D-16 34H14 D-27 53 34H15 D -31 51 34H16 D-30 52 34H17 D-32 50 34H18 D-33 49 34H19 D-28 34H20 D-11 0 34H21 D-34 91 34H22 D-117 34H23 D-119 34H24 D-118 34H25 D-178 34H26 D -35 90 34H27 D-124 34H28 D-116 34H29 D-36 83 34H30 D-187 34H31 D-102 34H32 D -37 92 34H33 D-1 01 34H34 D-38 48 34H35 D-39 34H36 D-40 78 34H37 D-109 34H38 D-112 34H39 D-111 34H40 D-108 34H41 D-41 81 34H42 D-42 47 34H43 D-113 34H44 D-115 34H45 D-114 85 Appendix A.-New and previously used well numbers in Glynn County, grouped by topographic map quadrangle-Continued This Report WSP 1613-E Bulletin 49-A This Report WSP 1613-E Bulletin 49-A 34H Brunswick East 1/ 24 ,000 (Cantin .) 34H46 D-43 46 34H47 D-100 34H48 D-44 82 34H49 D-45 80 34H50 D-46 79 34H51 D-183 34H52 D-47 77 34H53 D-48 74 34H55 D-50 75 34H56 D-52 71 34H57 D-51 72 34H58 D-99 34H59 D-53 73 34H60 D-185 34H61 D-56 31 34H62 D-98 34H63 D-54 30 34H64 D-55 32 34H65 J-1 173 34H66 J-2 174 34H67 J-3 175 34H68 J-4 176 34H69 J-5 177 34H70 J-6 178 34H71 J-7 179 34H72 J-8 203 34H73 J-9 34H74 J-1 0 34H75 J-11 34H76 D-57 34H77 D-58 34H78 J-12 34H79 J-13 34H80 J-73 34H81 J-215 34H82 J-221 34H83 J-47 34H84 J-217 34H85 J-31 45 34H86 J-32 34H87 J-33 180 34H88 34H89 J-45 J-222 34H Brunswick East 1/ 24,000 (Cantin.) 34H90 J-34 191 34H91 J-35 201 34H92 J-37 27 34H93 J-38 26 34H94 J-39 202 34H95 J-79 34H96 J-40 28 34H97 J-223 34H98 J-41 34H99 J-42 34H100 J-203 34H 101 J-218 34H 102 J-89 34H 103 J-43 29 34H104 J-216 34H105 J-220 34H 106 J-78 34H 107 34H 108 J-205 J-204 34H109 34H 110 J-206 J-77 34H 111 34H 112 J-211 J-202 34H 113 J-207 34H 114 J-209 34H 115 J-44 34H 116 J-208 34H 117 J-21 0 34H 118 J-48 5 34H 119 J-49 6 34H 120 J-51 200 34H 121 J-50 7 34H 122 J-1 03 34H123 34H 124 J-213 J-75 34H125 34H 126 J-52 J-88 34H127 34H 128 J-219 J-214 34H129 34H 130 J-104 J-74 34H 131 J-46 34H 132 (test well 2) D-182 86 This Report Appendix A.-New and previously used well numbers in Glynn County, grouped by topographic map quadrangle. WSP 1613-E Bulletin 49-A This Report WSP 1613-E Bulletin 49-A 34H Brunswick East 1/ 24,000 (Contin .) 34H133 D-59 34H 134 D-60 34H135 D-123 34H136 D-122 34H 137 D-194 34H 138 D-120 34H139 D-61 109 34H 140 D -62 108 34H 141 D-63 107 34H142 D -121 34H 143 J-200 34H144 J-14 183 34H 145 D-105 34H 146 D-64 144 34H 147 D-65 33 34H 148 J-15 34 34H 149 D-181 34H150 D-66 35 34H 151 D-67 34H 152 D -1 0 6 34H 153 D-192 34H 154 J-197 34H155 J-198 34H 156 J-102 34H 157 J-199 34H 158 J-25 36 34H159 J-16 139 34H 160 J-84 34H 161 J-17 146 34H162 J-196 34H 163 J-195 34H164 J-194 34H 165 J-193 34H166 J-192 34H 167 J-190 34H 168 J-189 34H169 J-191 34H170 J-187 34H 171 J-188 34H 172 J-186 34H 173 J-180 34H174 J-184 34H175 J-185 34H176 J-183 34H Brunswick East 1/24,000 (Contin.) 34H 177 J-182 34H 178 J-181 34H 179 J-179 34H180 J-178 34H 181 J-177 34H 182 J-176 34H183 J-175 34H 184 J-174 34H185 J-18 34H186 J-173 34H187 J-169 34H188 J-170 34H189 J-171 34H190 J-172 34H 191 J-168 34H192 J-167 34H193 J-166 34H194 J-165 34H 195 J-164 34H196 J-153 34H197 J-163 34H198 J-162 34H199 J-160 34H200 J-158 34H201 J-157 34H202 J-159 34H203 J-155 34H204 J-159 34H205 J-19 13 34H206 J-20 13a 34H207 J-154 34H208 J-161 34H209 J-148 34H210 J-21 14 34H211 J-22 15 34H212 J-149 34H213 J-150 34H214 J-146 34H215 J-147 34H216 J-152 34H217 J-23 34H218 J-24 34H219 J-140 34H220 J-139 87 This Report Appendix A.-New and previously used well numbers in Glynn County, grouped by topographic map quadrangle. WSP 1613-E Bulletin 49-A This Report WSP 1613-E Bulletin 49-A 34H Brunswick East 1/24,000 (Cantin.) 34H221 34H222 34H223 34H224 34H225 34H226 34H227 34H228 34H229 34H230 34H231 34H232 34H233 34H234 34H235 34H236 34H237 34H238 34H239 34H240 34H241 34H242 34H243 34H244 34H245 34H246 34H247 34H248 34H249 34H250 34H251 34H252 34H253 34H254 34H255 34H256 34H257 34H258 34H259 34H260 34H261 34H262 34H263 34H264 J-138 J-142 J-151 J-144 J-145 J-143 J-141 J-106 J-1 05 J-137 J-136 J-135 J-1 07 J-1 08 J-134 J-133 J-132 J-131 J-130 J-109 J-11 0 J-111 J-112 J-113 J-101 J-100 J-114 J-82 J-117 J-116 J-118 J-119 J-99 J-98 J-96 J-97 J-95 J-94 J-92 J-93 J-90 J-80 J-91 J-27 34H Brunswick East 1/ 24,000 (Cantin.) 34H265 J-28 34H266 J-26 34H267 J-85 34H268 J-82 34H269 J-81 34H270 J-83 34H271 D-171 34H272 D-177 34H273 D-170 34H274 D-168 34H275 D-169 34H276 D-161 34H277 D-162 34H278 D-163 34H279 D-164 34H280 D-165 34H281 D-166 34H282 D-167 34H283 D-160 34H284 D-158 34H285 D-159 34H286 D -157 34H287 D-156 34H288 D-155 34H289 D-154 34H290 D-153 34H291 D-69 34H292 D-152 34H293 D-151 34H294 D-72 34H295 D-68 43 34H296 D-70 42 34H297 D-71 41 34H298 D-191 34H299 D-147 34H300 D-148 34H301 D-73 34H302 D-146 34H303 D-145 34H304 D-144 34H305 D-74 34H306 D-149 34H307 D-143 34H308 D-142 88 This Report Appendix A.-New and previously used well numbers in Glynn County, grouped by topographic map quadrangle. WSP 1613-E Bulletin 49-A This Report WSP 1613-E Bulletin 49-A 34H Brunswick East 1/ 24,000 (Cantin.) 34H309 D-141 34H31 0 D-140 34H311 D-137 34H312 D-136 34H313 D-186 34H314 D-139 34H315 D-138 34H316 D-135 34H317 D-134 34H318 D-133 34H319 D-132 3.4H320 D-131 34H321 D-179 34H322 D-129 34H323 D-76 162 34H324 D-77 163 34H325 D-78 38 34H326 D-79 160 34H327 D-80 161 34H328 D-81 37 34H329 D-125 34H330 D-127 34H331 D-126 34H332 D-190 34H333 D-128 34H334 (test well4) J-227 34H335 D-188 34H336 D-173 34H337 (test well 5) J-228 34H339 D-200 34H340 D-201 34H341 D-202 34H342 D-203 34H343 D-204 34H344 (test well 7) J-229 34H345 J-231 34H346 J-230 34H347 34H348 34H349 34H350 D-250 34H Brunswick East 1/ 24,000 (Cantin.) 34H351 34H352 34H353 34H354 (test wellS) 34H355 (test well9) 35H Sea Island 1/ 24 ,000 35H 1 D-86 40 35H2 D-180 35H3 D-85 39 35H4 D-84 159 35H5 D -83 158 35H6 D-82 182 35H7 D-130 35H8 D-75 157 35H9 D -89 143 35H10 D-88 142 35H 11 D-87 141 35H12 D-90 44 35H13 D-91 156 35H14 D-92 154 35H15 D-93 153 35H16 D-94 152 35H17 D-193 35H18 D-95 151 35H19 D-96 150 35H20 D-97 35H21 C-1 148 35H22 C-2 149 35H23 C-3 147 35H24 C-4 193 35H25 D-150 35H26 D-176 35H27 J-129 35H28 J-128 35H29 J-127 35H30 J-126 35H31 J-125 35H32 J-124 35H33 J-123 35H34 J-29 165 89 This Report Appendix A.-New and previously used well numbers in Glynn County, grouped by topographic map quadrangle. WSP 1613-E Bulletin 49-A This Report WSP 1613-E Bulletin 49-A 35H Sea Island 1/24,000 (Cantin.) 35H35 J-30 164 35H36 J-122 35H37 J-201 35H38 J-121 35H39 J-120 35H40 D-195 35H41 D-196 35H42 D-197 35H43 D-198 32J Everett Cit1: 1/62,500 32J 1 32J2 32J3 32J4 32J5 32J6 32J7 32J8 32J9 32J10 32J 11 F-20 F-2 129 F-15 F-14 F-3 F-1 128 E-8 127 E-130 E-129 E-125 E-131 33J Everett City 1/62,500 33J 1 33J2 33J3 33J4 33J5 33J6 33J7 33J8 33J9 33J10 33J 11 33J 12 33J13 33J14 33J15 33J16 33J17 A-8 A-9 A-13 E-1 E-2 E-124 E-3 E-141 E-4 A-10 E-6 E-7 E-127 E-12 E-126 E-125 E-5 122 122A 112 112A 126 111 33J18 33J19 33J20 33J21 33J22 33J23 33J24 33J25 34J 1 34J2 34J3 34J4 34J5 34J6 34J7 34J8 34J9 34J10 34J 11 34J12 34J13 34J14 34J15 34J 16 34J17 34J18 34J19 34J20 34J21 34J22 34J23 34J24 E-123 E-15 E-16 E-17 E-18 E-19 E-22 E-147 34J Darien 1/24,000 D-1 D-2 D-3 D-4 B-1 B-2 D-5 D-6 D-184 D-7 D-8 D-9 D- 10 D-11 D-12 D-13 D- 18 D-19 D-20 D 21 D- 17 D-107 D-14 110 65 66 64 117 104 68 69 70 67 67A 103 103A 102 57 56 55 101 105 206 54 145 99 100 116 35J 1 34J2 .35J Altamaha Sound 1/24,000 D-189 C-11 90 This Report Appendix A.-New and previously used well numbers in Glynn County, grouped by topographic map quadrangle. WSP 1613-E Bulletin 49-A This Report WSP 1613-E Bulletin 49-A 32K1 32K2 32K3 32K4 32K5 32K6 32K Everett City 1/62,500 A -1 125 A-2 124 A-3 123 A-4 115 A-5 136 A-14 91 Appendix B. Well location map, Glynn County, Georgia. '= - - = i """ 93 Table 12 -Chemical analyses of ground water, Glynn County, Go (Analyses by U. S. GeoiOfical Survey) Well Number 33G3 33H10 33H103 33Hll3 33H115 33H118 33H127 33H127 33H127 33H127 33H127 33Hl27 33H133 34G1 34GJ 34CI 34G1 34GI 34GB 34G16 34H71 34H72 34H73 34H33 34H?3 34H74 34H74 34H74 34H74 34H74 34H74 34H75 34H77 34H78 34H78 34H79 34H91 34H94 34H94 34H120 34Hll3 34H122 34H125 34H125 34H132 34H132 34H132 34H132 34H132 34HI32 34H132 34H132 34H134 34.8334 34H334 34H334 34H334 34H337 34H337 34H337 34H337 34H337 34H337 34H337 34HS37 34H33? 34H337 34H337 33H344 34J9 Own"' State ofGeoiia George Cowman Allied Chemieal Corp. WeU 3 Brunswick PuJp .and Paper Co. Well 6 Brunswick Pulp and Paper Co. Well 8 Brunswick Pulp and Paper Co. Wellll U.S. Geological SW'Vey Test Well 3 do do do do do U.S Geologica] Survey Test WeU 6 Babcock & Wilcox do do do do Jekyll Island Autbority do Hercules Powder Co WeU H Hercules Powder Co. Well I Hercules Powder Co. Wtll J do do Hercute5 Powder Co. Well K do do do do do Hercule5 Powder Co. Wen L Hereules Powder Co Well N Hercules Powder Co . WeU 0 do Hercules Powder Co Well P City of Brunswiclc., North Shipyards Well City of Brunswick, South Shipyards Well do City of Brunswick, F St Well Golden Shores Seafood 1 Brunswick Laundry US Geologiaal Survey TPSt Weill do U.S. Geologicaf Sliney Test Well 2 do do do do do do do City of Brunswick, BrutmVick Villa Well U.S. Genlogica.t Survey Test WelJ 4 do do do U.S. Geological Survey Test Well 5 do Ftee Flow do do do do do do do do do U S. Geological Survey Test Well 7 Hany Liles Interv:a.l gmpled (feet below land surface) 610- ? 500-665 501-983 550-1,076 558-94? 5601,003 823-842 1 880-9021 982-1,002 823-1,002 823-952 82~952 520-790 600.1,006 1 660-1,0061 720-1.006 1 970-1,006 1 584-1,006 510-717 54Q-?Ei7 5601,062 498-950 546-1,051 546-1,051l 9301,051l 560-1,039 600-1,039 1 810-1,039 1 935-1,039 1 1,035-1,039 1 560-1,020 560-1,000 555-1,018 545-1,014 545-1,014 459-1,040 620-736 574-805 574-805 478-957 ~60 -860 ('1) 546-SOO 546-600 540-920 540-920 950-1,003J 950-1,003J 950-1,0033 1,0531,1033 1,053-1,1033 1,053-1,1033 518-942 880-900 1 960-980 1 802-980 802-980 502-5224 567-607 680-6984 776-7994 878-898. 987-1,0074 1,182-1,2004 1,2811,3004 1,385-1,400' 1,487-1,503 1,1891,503 504-770 680-780 Date of collection 2-27-63 10- 5-62 8-10-62 8-10-62 S-10-62 5-11-64 S-16-62 8-20-62 8-20-62 8-21-62 2-18-63 5-13-64 5-13-64 6-11-64. 6-11-64 6-11-64 6-11-64 6-11-64 2-14-63 10- 5-62 8-13-62 8-13-62 S-13-62 4- 6-64 4 &-64 10-18-62 10-18-62 10-18-62 10-18-62 10-18-62 10-30-62 2-14-63 S-13-62 8-13-62 2-14-63 5- ?-63 2-14-63 8-10-62 10- 8-63 8-10-62 8-10-62 8-22-62 S-13-62 5-13-M 3-19-62 5-14-64 3-19-62 2-12-63 5-14-64 3-19-62 2-13-63 5-14-64 10- 9-63 9-10-62 9-11-62 9-11-62 5-13-64 6- 6-63 6-27-63 6-11-63 6-18-63 8-13-63 8-28-63 12-12-63 4-20-64 5- 5-64 5-26-64 5-26-64 5-13-64 10- 5-62 Temperature n> - 73 77 80 81 78 82 83 82 82 76 80 78 78 78 78 78 .. 71 73 82 81 8< - 83 83 - 83 - 82 82 84 8< 81 80 75 78 77 78 79 79 77 77 83 81 83 81 79 84 81 81 78 82 81 81 81 80 82 84 84 84 84 82 82 83 8< - 77 78 MiUigrams per liter Silica (Si0 2) 26 26 35 35 35 36 35 33 33 35 35 37 36 35 35 36 34 36 40 35 35 35 31 34 33 37 37 38 38 37 37 40 35 34 37 32 44 34 34 35 35 35 35 35 36 35 38 46 37 26 29 29 11 20 35 36 38 33 34 34 33 36 33 34 34 29 27 32 35 37 Iron (Fe) 0.02 .31 .01 .o! .01 .08 .03 .02 .01 .01 - .17 .11 .28 .37 .49 - .07 .35 .38 .02 .01 .00 -- .02 .oJ .00 .00 .01 .03 - .OJ .01 .09 .02 - .00 .01 .00 .30 .01 .01 .II .22 .II .07 .59 .07 .12 .35 .06 .02 .01 .04 .10 .11 .26 - .-. .. .-. - .09 .25 Calcium Magnesium (Co) (Mg) 684 478 40 26 39 25 51 29 46 26 46 35 38 28 46 27 93 54 86 53 53 33 59 38 45 37 75 49 82 59 85 66 131 Ill 71 51 61 31 37 23 120 72 45 27 142 86 172 118 160 119 46 28 57 35 58 35 58 35 66 42 45 28 46 23 72 42 125 75 128 79 46 28 33 29 46 26 45 28 54 33 61 40 83 64 56 37 75 54 82 47 48 26 45 26 55 19 47 25 169 95 148 81 139 82 40 24 30 9 55 32 46 28 43 33 39 27 168 112 232 132 228 144 18< 136 192 127 116 71 120 85 38 27 39 25 114 73 38 26 46 28 Sodium (Na) 4,400 22 16 24 21 28 23 29 105 100 35 72 30 99 124 139 265 101 25 16 215 22 260 340 340 30 58 58 58 80 30 20 88 225 225 28 13 28 28 44 62 132 78 104 85 27 20 19 27 224 168 195 15 36 32 24 24 18 300 465 500 355 420 165 232 14 14 240 13 28 Pot.assium (K) 122 2.1 1.8 2.1 1.9 2.5 2.6 2.8 3.9 3.7 2.0 2.4 2.7 3.0 3.5 3.7 6.0 2.8 2.5 1.4 4.9 19.00 5.8 12.0 11.0 2.2 2.6 2.6 2.8 3.2 2 ..4 1.9 3.2 5.1 5.3 2.7 1.7 2.0 1.7 2.3 2.6 3.9 2.6 3.4 4.4 2.0 2.2 1.9 1.9 11.0 9.0 7.2 1.4 9.0 2.4 2.0 2.6 2.6 8.4 11.0 12.0 10.0 9.8 5.4 6.4 2.5 2.0 4.8 2.4 1.9 Bicarbonate (HC0 3) 152 152 140 142 144 144 122 124 146 146 146 152 144 145 145 143 142 145 176 140 142 140 142 144 134 148 146 148 146 148 140 148 144 142 144 142 144 142 142 142 142 146 148 148 144 142 144 146 151 138 140 139 144 18 142 142 148 144 144 138 138 136 140 144 144 136 138 126 152 148 Sulfate (S04) 2,140 88 72 121 98 122 97 107 271 253 126 160 136 228 278 309 575 233 139 72 389 93 490 498 494 113 148 !56 160 193 107 98 203 415 462 108 89 98 106 133 181 317 13" 260 288 101 98 101 101 862 722 584 84 107 127 100 102 84 242 714 626 650 538 352 366 88 95 383 77 106 Chloride Fluoride (Cl) (F) 7,600 1.9 15 .8 16 .6 36 .6 26 .6 53 1.0 31 .6 44 .6 188 .7 178 .6 62 .6 113 .7 56 1.1 117 .6 221 .6 248 .7 466 .6 180 .6 39 .6 16 .6 360 .7 27 .6 450 .7 720 1.1 720 1.1 42 .7 90 .7 96 .7 96 .7 132 .7 42 .7 27 .5 135 .7 378 .7 405 .7 42 .6 16 .5 40 .5 40 .7 70 .6 98 .6 220 .6 130 .6 178 .6 110 1.1 47 .8 24 .6 26 .5 33 .6 205 1.6 160 1.5 272 1.3 18 .9 38 .7 52 .6 36 .8 45 1.0 18 .9 550 .7 830 .8 925 .8 730 .9 775 .7 328 1.0 460 1.0 18 1.0 14 .7 444 .7 15 .9 39 .7 Nitrate (NO a> 39.0 .0 .0 .I .1 .0 .2 .I .I .0 .0 .0 .0 .0 .0 .0 .I .0 .1 .0 .3 .I .5 .4 .4 .0 .0 .o .0 .0 .0 .I .0 .4 1.8 .I .0 .0 .0 .1 .I .3 .0 .0 .I .0 .I .1 .0 1.0 .8 .0 .0 .1 .I .I .0 .0 3.1 2.8 4.0 .4 3.0 .4 .9 .0 .0 .I .1 .o Bromide Iodine (B<) (I) ---- --- - - 3.1 .3 - -- - .. --- 6.8 5 2.9 3 - - - - ---- - - - .. - - - - - - 7.0 .3 5.9 .4 --- - .. .. -- -- - - - - --- -- - -26 -- - -- 0 - ---- -- -- --- - ---- - .. - - -- - --- - - - - 3.2 .3 .5 .8 4.7 .8 4.9 .4 3.4 .4 6.8 .4 8.1 .4 9.0 .4 4.7 .3 2.1 .3 .53 .5 1.5 1.0 3.4 .3 - - Dissolved solids (residue at ISO' C) 16,400 328 274 400 338 472 338 388 940 910 488 642 442 910 1,050 1,160 2,010 882 447 300 1,470 348 1.750 2,380 2,370 406 540 550 556 664 398 343 708 1,470 1,500 398 299 364 368 470 592 1,090 636 994 760 456 334 349 376 1,740 1,470 1,520 288 254 442 421 374 298 2,060 2,730 2,940 2,460 2,470 1,350 1,670 288 318 1,540 320 384 Hardness as Caco 3 CalcitJID magnes~um Non carbonate 3,680 206 200 246 222 258 210 226 454 432 266 302 264 390 449 464 782 387 278 188 596 224 708 915 890 230 286 288 288 337 228 210 352 620 644 232 200 222 226 270 316 470 292 410 398 228 220 216 221 812 705 686 198 112 268 230 244 208 880 1,120 1,160 1,020 1,000 580 650 204 201 583 202 230 3,560 82 86 130 104 140 110 124 334 313 146 178 146 271 330 367 666 268 134 74 479 109 592 797 780 108 166 167 169 216 113 89 234 504 526 116 82 106 110 164 200 350 170 2S8 280 112 102 97 98 699 590 572 80 90 152 114 122 90 762 1,010 1,050 908 886 462 53 92 88 480 78 108 Specific conductance (micromhos at 25C) 18,800 443 422 578 505 604 508 564 1.,270 1,230 622 813 617 1,140 1,360 1,480 2,440 1,140 641 400 1,960 514 2,380 3,160 3,140 559 780 793 815 985 567 497 1,040 2,060 2,180 550 446 541 556 716 879 1,420 902 1,180 1,100 551 530 503 528 2,300 1,900 1,980 440 410 646 545 566 430 2,750 3,700 4,000 3,310 3,450 1,790 2,190 420 435 2,120 426 520 Laboratory pH 7.2 7.9 7.8 7.7 7.9 7.8 8.0 7.9 7.7 7.7 7.8 7.6 7.5 7.6 7.8 7.8 7.6 7.7 7.7 8.0 7.8 7.8 7.7 7.5 7.5 7.9 7.6 8.0 7.8 7.6 7.8 7.7 7.8 7.7 7.6 7.8 7.9 8.0 7.6 8.0 7.9 7.8 7.8 7.6 7.8 7.8 8.0 7.8 7.8 7.8 7.7 7.6 7.6 8.7 7.9 7.8 7.7 7.5 7.2 7.2 7.3 7.6 7.2 7.4 7.7 7.9 7.8 7.5 7.6 1.9 1 Collected during drilling through sampling pipe at upper depth. 1 Tb.iefsample. 3 Sampled by pipe cemented in designated intervals. 4 Sample obtained durin,e: drilline: by packH test TablE> 6 .- Aquifer constant.< determined by Cooper-Jacob modified, and Theis n011equi/ibrium methods from recovery of water levels. Well Number 1962 Christmas shutdown at Brunswick Pulp and Pap<>r Co. (max. Q = 42.3 mgd l T(gpd/ft) s 1963 Christmas shutdown at Brunswick Pulp and Pap<>r Co. (max. Q = 52.3 mgd I T(gpd/ft) s 1964 powt>r failurE> at Brunswick Pulp and Pap<>r Co. (max. Q = 62 .5 mgd ) T(gpd/ft) s August 1964 shutdown at Hercules Powder Co. (max. Q = 20.2 mgd) T(gpd/ft) 5 33H133 - -- - - .... 34H344 -- ..... . .... - .. - "c ' 0 34H91 N E"" 1""'' 34G20 ~ 2,000,000 1,700,000' - -- 0.0003 0.0006 1 - - - 2,100,000 . .... 10,000,000 5,000,000 1 0.0006 - 0.0006 0.0002 1 - .. -_ ...;""..:.,'' 34H328 -- - - - - -- - - - - "cc'.. 33H131 _., - - - - ::J -- - -- - - Composite values for 33H133, 34H344, and 34H91 --- - Average values for upper water-bearing zone ~ - - 1,500,000 1,300,0001 - 1,200,000 -- 1,000,000' 1,600,000 - 1,500,000' 0.0004 0.0006' 0.0004 0.0007 1 0.0006 0.0005 1 -- .,_ - - -- - -- - -- 1,200,000 -- . ... - - - -- 0.0006 -- 1964 Christmas shutdown at Brunswick Pulp and Paper Co. (max. Q = 48.3 mgd l T(gpd/ft) s 1,300,000 1,300,000' - -- 0.0002 0.0002 1 -- - - Avffage of selected values T(gpd/ft) s 1,400,000 1,300,000' 1,200,000 0.0003 0.0004' 0.0004 1,900,000 1,600,000' 0.0005 0.0006' 2,600,000 2,000,000 1 2,300,000 1,700,000' - 0.0004 0.0005' 0.0004 0.0006' - - 1,500,000 1,500,0001 0.0004 0.0004 1 ",:.' "c' ";: N0 ... ~ ~;: .0..:~1"\' 33H127 1,800,000 0.0003 1,300,000 1 0.0004 1 33H334 - - Average values for lower water-bearing zone 1,400,000 1,400,0001 --- 34G1 - - 2,400,000 34H337 - 2,500,000' - 1,400,0002 1,400,000' ~ "c ' 33G3 0 - N - "";c::; 33H117 - - 1,700,000 - 1,700,000' - 1,700,000' ."",0:.'' 2l - - 1,900,000' Composite values for 33Hll7 and 34H337 - ;":' - -E Composite values for 34G1, 34H337, 0 "" and 33G3 1,600,000 1 Average values for both water-bearing zones (exclusive of well 34G1) ' Theis nonequilibrium type curve 2 Well tapped 567'-1,171' interval .l Well tapped 567'-936' and 1,189'-1,503' intervals 0.001 0.001 1 - - - 1,400,000 1,500,000' -- - 0.00007 0.0005 1 - - 1,400,000 1,200,0001 1,400,000 1,300,0001 - 0.0005 0.0007 1 0.0001 - 1,700,000 1,800,0001 ~ -- -- 0.0005 -- 0.0006' - 0.0007 -- 0.0003' - 0.0005 - 0.0007 1 -- 0.0005 1 -- 0.0002 1 -- - -- -- - - 2,100,000 - 1,800,000' - 1,400,000.1 - 1,400,0001 - - - - - 1,500,000 - 1,400,0001 - 1,700,000 - 1,400,0001 0.0006 0.0008 1 0.0004 0.0004 1 ...... 0.0004 0.0005 1 0.0003 0.0004 1 - - 2,300,0004 1,800,000 1 2,900,000 2,400,000 1 -- -- --0.0008 1 - --- - - - - - - -- - 4 Well tapped 567'-919' interval 5 Exclusive of 1964 Christmas Brunswick Pulp and Paper Co. shutdown test 6 Exclusive of 1964 power failure at Brunswick Pulp and Paper Co. 0.0002 0.0002 1 - 1,500,0005 1,400,0001 s 1,400,000 -- 1,400,000 ..... 0.0004 0.0005 1 0.0005 0.0007 1 -- - - 2,200,000 2,200,000 1 1,400,000' 1,400,0001 1,700,0005 1,700,0001 1,600,000 1,600,000 1,700,000 1,400,0001 0.00055 0.0004 1 s 0.0005 0.0005 0.0007 1 0.0005 0.0004 1 0.0005 0.0007' 0.0005 0.0005 0.0003 0.0004 1 - 1,700,000 0.0005 1,600,0001 0.0006 1 Table 7.- Aquifer constants determined from long term water-/eue/ declines. Apparent transmissivity (T') and storage coefficient (S') Well Number c(1) 0 .N.. (1) 0. 0. ::J ... (1) (1) ~ c 0 0 ....:IN 32H1 1 3~H24 1 32H26 1 33H3 1 33H10 1 33H36 1 33H52 33H78 1 33H119 33J22 1 34GB 34G17 34G20 34H91 34H97 34H125 34H147 1 34H205 34H328 1 34J1 1 34H9 35H12 35H37 Average 34H127 34H334 Average Type-curve analysis T' S' (gpd/ft) 2,100,000 4,600,000 2 2,100,000 2,200,000 830,000 1,200,000 1,800,000 1,100,000 720,000 2,100,000 1,000,000 870,000 1,800,0002 3,800,0002 2,700,0002 1,400,000 2 3,600,0002 850,000 1,000,000 1,500,000 3,100,000 1,000,000 1,200,000 1,500,000 0.0006 0.00072 0.002 0.006 0.05 0.008 0.0009 0.009 0.06 0.004 0.006 0.005 0.008 2 0.002 2 0.0022 0.05 2 0.005 2 0.01 0.005 0.0004 0.0002 0.005 0.01 0.004 2,800,000 2 1,600,000 1,600,000 0.001 0.006 0.004 Remarks Good fit Good fit Good fit Good fit Fair fit Fair fit Fairly good fit Good fit Fair fit Fair fit Fair fit Fair fit Poor fit Poor fit Poor fit Poor fit Poor fit Good fit Good fit Good fit Good fit Good fit Fair fit Distance r (ft) 65,600 48,200 37,400 29,600 18,800 17,700 16,600 12,800 2,900 35,800 62,500 38,100 44,000 19,500 17,500 10,600 30,800 42.600 41,800 59,500 51,700 49,800 46,500 Poor fit Poor fit 4,600 12,800 Actual transmissivity (T ) and storage coefficient (S ) Well Number Type-curve analysis T s (gpd/ft) Remarks .c ~ ( lcV)l 0 0 il:IN 34G1 34H134 34H160 Average 3,800,000 1,600,000 940,000 2,100,000 1 Well may have insufficient casing 2 Value not used in average 0.005 0.003 0.01 0.004 Poor fit Good fit Fair fit Distance r (ft) 22,000 6,700 37,200 Table 9.-Physical and hydrologic properties of cored samples from wells 33H114 (Brunswick Pulp and Paper Co. 7), 34H132 (test well 2), and 34H337 (test well 5). Depth (feet) Well34H337 (test well 5) 118-128 178-188 547-567 567-587 587-607 678-698 779-799 935-954 1,088-1,105 1,490-1,503 Core Recovery Percent Porosity (percent) Specific yield (percent) Coefficient of Permeability (gpd/fe at 60 F) Horizontal (PH) Vertical (Py) 40 39.7 15.3 -- 2.0 10 42.5 27.2 -- 8 55 42.5 15.5 - 0.08 20 32.5 25.6 --- 3 35 31.3 21.4 --- 1200 5 54.0 46.2 -- 29 42.1 31.0 - 20 11.9 4.7 -- 24 1.7 0.3 -- 23 24.5 19.8 -- 900 50 0.00006 0.00003 40 PH/Pv Lithology - Clay - Clay - Fine grained sand- stone - Sandy limestone - Fossiliferous lime- stone - do - Limestone - Limestone - Limestone -- Limestone Stratigraphic Interval Miocene Miocene Miocene(?) Oligocene(?) Upper Eocene (Ocala Limestone) do do Middle Eocene (Claiborne Age) do Lower Eocene (Oldsmar Limestone) Well34H132 (test well 2) 519-539 10 560-580 5 642-662 25 682-702 5 744-765 5 867-888 27 1,046-1,051 22 21.7 15.8 19.2 49.6 34.6 11.2 3.5 10.7 0.1 5.6 10.0 10.7 120 39.2 135 16.3 0.7 1.7 .005 0.3 .01 7 9 50 140 3 .2 .0001 0.014 1.1 2.4 .96 .23 .0025 100 Fossiliferous gray limestone do do do do Dolomitic limestone Oligocene(?) Upper Eocene (Ocala Limestone) do do do do Middle Eocene (Claiborne Age) Well33H114 (Brunswick Pulp 7) 615-635 25 708-712 27 712-718 87 900-912 50 21.8 0.0 0.06 46.3 35.8 -- 39.7 27.8 70 22.5 15.1 .05 5 160 - .001 .012 .48 50 Fossiliferous gray limestone do do Dolomitic limestone Upper Eocene (Ocala Limestone) do do do HYDOLOGIC REPORT 1 PLATE 1 2~~r-::;;-z:;=::::::::::--'-c:-::~-.;-----.~=-:::;::::--H---::::;;;;;""f-8:~~-D~;;;-;~~~:-~T-----...s;:------------7-----;r-:7____,,:=--:J::-~--=~==-l831''2'7''320'" 3o" [ 33 ,.II. ..-.......... - 36 ~ I I I p' AND co. I I WELL Fl I I I I I I ( \ ~ I \ <. \ \I"T\ \~ \ \ \ \ \ \ \ \ \ \ \ \ \ \ BRUNSWICK AIRPORT EXPLANATION 50- lsochlor Shows chloride dis1ribution, in parts per mHiion. Dashed where control less accurate. lsochlor interval varies 18 Chloride content, Aug.l962 Ill (4) Well number (company number) 10---- Potentiometric contotX Shows altitude of potentiometric surface . Contour interval 5 feet; datum is mean sea level air-conditioning well Domestic or @ Industrial or municpal well Oil-test well 7780 ~ Bose mop af ter U.S. Geological Survey 1:24,000 quodronq les ~====~~~~==0 ==========I MILE Map of potentiometric surface and areal distribution of chloride m water, Brunswick, Georgia, August 1962. -- I I ..., 18 ~ <::::: I_:}_ I .~.., 100{1) ,..... II II1"1) 10' --- BRUNSWICK PULP .AND -~~~~ PAPER CO. WELL FIELD RIVER I '\ < \fT\ \::JJ \ \ \ \ \ \ \ \ \ / CK RIVER ----- -'"' -- I \ HYDROLOGIC REPORT 1 PLATE 2 @3 ~ ~ 33 _w_ ~ __.,._ _....___ ~ ~ ~ --""--- -~ 36 37 -""'- EXPLANAriON ---100- - - lsocnlor Shows chloride distribution, in ports per miRion. Dashed where control less accurate. lsochJor interval varies 20 Chloride content, Nov. 1964 112(5) Well number (company number) --10---- Potentiometric contour Shows altitude of potentiometric surface. Dashed where control less accurate. Contour interval 5 feet; datum is mean sea level Domestic or air-conditioning well @ Industrial or municpol well + Oil-test well 81 . 30 Bose mop after U.S.Geologicol Survey 1:24,000 quadrangles c=~==c=~:3==~~==~~==~=0~===========================1 MILE 27'30" Map of potentiometric surface and areal distribution of chloride 1n water, Brunswick, Georgia, November 1964.