' I STATE OF GEORGIA DEPARTMENT OF NATURAL RESOURCES Joe D. Tanner, Commissioner THE GEOLOGIC AND WATER RESOURCES DIVISION Sam M. Pickering, State Geologist and Division Director ' ATlANTA 1976 . THE GEOHYDROLOGY OF BEN HILL, IRWIN, TIFT, TURNER, AND WORTH COUNTIES, GEORGIA by THOMAS W. WATSON . HYDROLOGIC ATLAS GEORGIA DEPARTMENT OF NATURAL RESOURCES THE GEOLOG IC AND WATER RESOURCES DIVISION THE GEOHYDROLOGY OF BEN HILL IRWIN. TIFT. TURNER. AND WORTH COUNTIES, GEORGIA THOMAS W. WATSON HYDROLOGIC ATLAS 2 SHEET 1 OF 3 A ~ I Figure 1. THICKNESS OF THE NEOGENE FORMATION B - . ,.-:--. _, 160 90 140 '-'\. 83 '._...-.._fl I L--- 320 / I ) ; I EXPLANATI ON 100 ______...,.. 150------ D Denotes arc;~ where Neoge ne formations arc found ai or ncar the surface Equal-thickness Contour Shows Uric/mess o( Neogene formation ouerfying the l'rindpal Artesian Aqrli(er. Con lour intr~rua/ is 50 {t!ei Control Point Denol.cs area where Principal Artesian A(JUifer i~ found at or ne ar the .~urfacc INTRODUCTION Ben Hill, Irwin, Tift, Turner, and Worth Counties are located in southwest Georgia on the Coastal Plain. These five counties were selected for study because of their steady population growth in the past 10 years. New developments in agriculture, an abundance of good quality water, and an expanding transportation system promise to make this area of south Georgia one of continuing growth. Since ground water has been a significant aspect in the development of these counties, it is important to know how much water the aquifer is capable of producing, the quality of the water, and bow to insure the availability of this resource for continued use. GEOLOGY The surface sediment of the study area is primarily a sand-clay mixture that varies in thickness from less than 50 feet to several hundred feet. This series of shallow, unconsolidated sediments was deposited in the last 25 million years, a period of time known as the Neogene . Examinations of these sediments indicate that most were deposited in ancient seas that once covered the area. On the land surface, it is generally difficult to distinguish the contact between different geologic formations, since physical weathering and erosion commonly cause the contacts between adjacent rock units to appear gradational. In the southeastern portions of Tift and Irwin Counties, these Neogene age sediments become quite thick, as indicated by the contour lines on Fig. 1 and the type of sediment changes at depth from a mixture of poorly sorted sand and clay to very fine-grained, fissile clays and silts. The principal artesian aquifer, which supplies water to all municipal and industnal wells and most deep domestic wells in this area, underlies the unconsolidated sediments: This aquifer consists primarily of the Suwannee and Ocala Limestone and many lens-shaped bodies of Neogene limestone overlying the Suwannee. The principal artesian aquifer can be thought of as a wedge, roughly 250 feet thick in the northwestern portion of the study area, thickening to more than 400 feet in the southeast. If it were possible to remove the Neogene sands and clays, exposing the top of the principal artesian aquifer, one would see a rather rugged landscape. The surface of the principal artesian aquifer has been extensively eroded and marked with sinkholes, giving this buried surface considerable relief. When drilling, therefore, it is helpful to recognize that the depth to limestone can vary by tens of feet within a short lateral distance. Another important feature of interest to the well driller is found in southern Tift and Irwin Counties. Figures 1 and 3 both indicate a depression in the surface of the principal artesian aquifer along with a thickening of the overlying sediments. Within this depression the limestone is either missing entirely, or it exists at depths greatly exceeding those in other portions of the study area. High yield wells in this area are commonly difficult to complete because of the tight, impermeable clays fillin g the depression . Most drilled wells in the study area draw at least part of their water from the principal artesian aquifer. Most domestic wells are drilled through t he sand and clay layers of the Neogene and are finished in the top few feet of the limestone. Water users who require more water than the average domestic well can provide, have drilled a larger diameter well or have drilled deeper into the aquifer. Pump and aquifer tests at the Tifton, Sycamore, and Fitzgerald city wells indicate that sustained yields of 1000 gallons per minute and more are possible for large wells tapping the principal artesian aquifer (Sever, 1969). Scale I:250,000 E5========~O=======:::i'c:===:==:==:==:==:==:;:i'[:o=======::i"E===:==:==:==:c:===:=320 Statute Miles E53::::E3::::::E30====::::i'=::==::==::==::=3'10=====1E5c:=c:=c:==::=320====:::::i"~====330 Kilometers SELECTED REFERENCES 1. Cooke, C. W., 1943, Geology of the Coastal Plain of Georgia: U. S. Geol. Survey Bull. 941 , 121 p. 2. Hem, J . D., 1970, Study and Interpretation of the Chemical Characteristics of Natural Water: U. S. Geol. Survey Water-Supply Paper 1473 (2d ed.), 363 p. 3. Herrick , S. M., 1961 , Well Logs of the Coastal Plain of Georgia: Ga. C:eol. Survey Bull. 70 , 462 p. 4. Herrick, S.M., and Vorhis, R. C., 1963, Subsurface Geology of the Georgia Coastal Plain : Ga. Geol. Survey In f. Circ. 25, 78 p. 5. Herrick, S. M., and Wait, R. L., 1956, Ground Water in the Coastal Plain of Georgia: Am. Water Works Assoc. Jour., Southeastern Sec., v. 20 , no. 1, p. 73-86. 6. Krause, R. E. , and Gregg, D. 0., 1972, Water from the Principal Artesian Aquifer in Coastal Georgia: Ga. Div. Earth & Water, Hydrologic Atlas 1. 7. Owen, Vaux, Jr., 1963, Geo logy and Groundwater Resources of Mitchell County , Georg ia: Ga. Geol. Survey Inf. Circ. 24, 38 p. 8. Sever, C. W., Jr., 1965 , Ground Water Resources of Bainbridge, Georgia: Ga. GeoL Survey lnf. Circ. 32, 10 p. 9. _ _ 1966 , Reconnaisance of the Ground Water and Geology of Thomas County, Georgia : Ga. Geol. Survey lnf. Circ. 34, 14 p. 10. _ _ 1969, Hydraulics of Aqu ife rs at Alapaha, Coolidge, Fitzgerald, Montezuma, and Thomasville, Georgia: Ga. Geol. Survey lnf. Circ. 36, 16 p. 11. Stiff, H. A., Jr., 1951, The Interpretation of Chemical Water Analysis By Means of Patterns: Jour. of Petroleum Technology , v. 3, no. 10, p. 15-17. 12. Stringfield, V. T., 1966, Artesian Water in Tertiary Limestone in the Southeastern States: U. S. Geol. Survey Prof. Paper 517 , 226 p. 13. U. S. Dept. of Comm ., 1963-72, Climatological Data of Georgia: National Oceanic and Atmosp heric Administration, Environmen ta l Data Service. 14. U. S. Public Health Service, 1962, Drinking Water Stand ards: Public Health Service, Pub. 956. 500 mean sea level 500 WORTH CO. TURNER CO. B 500 mean sea level 500 I CRISP co. TURNER co. I I I TURNER co. IRWIN co. ~ ~ u ~ 0 0 "' ~ > "' ~ 5 0 ~ 0 ~ 0 <1 ~"' PRINCIPAL ARTES IAN AQU IF ER TURNER CO. TIFT CO. PRINCIPAL ARTES IAN AQU IFER c 500 e ~ ~ N ~ ~o0000::-~>: "' -" o 0 ~ ~ u ~ E "0' ~ ..~,..X .:; ; ::; ~ u ~ c' 500 mean ua levelr~~~~~~@~PR~IN~CI~PA~L~AR~TE~SIA~N~AQ~UI~FER~~~~~~~~~~~~g~~~g~~tmean sea level 500 500 Figure 2. GEOLOGIC SECTIONS o 0 . o0 >- A' -""' 500 JOOO 8' 500 mean sea level 500 1000 GEORG I A D EPART MEN T OF NA T U RAL R ESOURC ES TH E GEOL OGIC AN D WAT ER RESOURCES DI V ISION THE GEOHYDROLOGY OF BEN HILL. IRWIN. TIFT. TURNER. AND WORTH COUNTIES. GEORGIA THOMA S W. WATSON HYDROLOGIC ATLAS 2 SH EET 2 OF 3 I I I r- " --- 172-- - - Figu re 3. CONF IGU RATIO N O F T H E T OP O F TH E PRI NCI PA L A RT ESI A N AQUI FE R ' zoo --- - . 164 \ 188 r-- f - 55 L_~ EXPL ANATIO N ~------100 _ _ _ _ . . . . . . . - - ---125------------ Structure Contour Map Co nn ect s p o in ts o n lop o( tlw Pr in cip al Artesia n A qu i f er, w/Jic/J are o{ equal e levation a bove m ean sen le vel. Co n to ur interval is 5 0 feet in areas be lo w M.!a le vel and 25 fee t in meas above sea level. Control Point I _]3145 ' I ,. 1 2 r-----------------------------------------------------------------~ I I f10 f- 8 1- 1\ 7- w > 0 .Q 0 6- 5 ~ v _j w > w _j 1- 240 N_230 .... .. 2 _ .. .. .. LEVEL ... . .. ... ...- 220 1- v II - 210 1 1 1 1 1 oLJ,~ _o'~ILI L' ~J~~ l I LI L I ~ I _JjL"~ I ~I LI L I J~~l _LLLI ~I_JLj" ~ I I ~_LJ"~l 1~I LI L I I~Jj_" LLI L~ I L I J~Ll I~_I LI LI ~ Jo_I LLIL~_JL' l L I ILI~IL~ I 200 1968 1969 /970 197 1 1972 Figure 5. Chart comparing monthly fl uctuation in rainfall with water level fluctua t ion in a n observation well in Tifton, Georgia. SCALE 1: 250,000 ''E=r:=:E==r= ::E=30= ==== ==::::i':=:=::=o:=:=:=:=:=:=:=:===::=i0i ========15E:=:=:=:=:=:=:=:=:=:==:==:=320 Statute Miles ''Ecao=3====::::1=:==:==:==:=31 0====::i"=:==:==:==:=~'I::o====="E=:==:==:==330 Kilometers Figure 4. WATE R L EV EL IN TH E PRINCIPAL A RT ESIAN A QU IF ER RAINFALL Rainfall in southwest Georgia averages approximately 46 inches per year. An examination of rainfall data, however, shows that rainfall is not evenly dist ributed throughout the year (U. S. Dept. of Comm., 196 2). Wet months ca n be followed by ex tremely dry months during which water sources at or near the surface are depleted by evaporation. A fract ion of the rainfall is not returned directly to the atmosphere but is absorbed by the earth and percolat es downward into the layers of rock and sediment. This water is stored underground in a natural water supply system that is the principal artesian aquifer. Since evaporation has only a small effect on ground water levels in the report area, deep wells generally maintain adequate water levels during periods of drought. Figure 5 shows t he water level record of a U. S. Geological Survey observat ion well in Tift on, along wit h rainfall records for the same time period. It can be seen that the monthly rainfall variation is rather high, whereas the water level in the well fluctuat es much less . WATER LEVEL The water level map of the principal artesian aquifer is constructed from measurements of water levels in wells known to t ap this aquifer. Geologic conditions in the report area are such that the ground water is under pressure, causing it to rise in a cased well, above the level at which it is first encountered in drilling. The aquifer in the study area is thus an artesian aquifer. The water level map can be used to predict the unpumped water level in a proposed well by subtracting the elevation of the ground water level from the elevation of the land surface at the well site. The remainder will be the approximate distance from the land surface to the static water level in the complet ed well. It should be emphasized that this is strictly an estimate of static water level. Actual levels may vary some what. Generally, the contours are more reliable where data points are closely spaced. To date, pumping has no t caused any obvious changes in water levels of the principal artesian aquifer in the study area. Heavy dependence upon ground water from deep wells is comparatively recent. This office, in cooperation with the U. S. Geological Survey will continue to monitor water levels and ground water quality in this area to detect any changes which might affect gr0:--I zl 219 223 8[;:) ~-- ----..---132)...._/ / ~I 1- ,.J 24 5 ::> 226 .01 u I ~ ~ u 227 :3 1 225 '] 50 r .238 235 234 \ \ \ \ I I I L _-- ~N_HILL gouN~ 1 2 15 I - II ./ - J1 IRWIN - - - COUNTY - 226 . 221 231 _j 1 '::H---------------- r 194 190 193 I ) / ' I 731 30' COUNTY 1/ ---------~_/ I I I J r" ' "i '~- EX PLANATION 1oo-------- 125- - - - - - - - L ____ _ _ _ 84 18 9 188 WORTH CO Water Level Co ntour or Potentiometric Surfaee map Sho ws alii tude of artesian water aboue rni' an sea lr:vcl. Co n /(mr interuul is 25 feet. Control Poin t GEORGIA D EPARTMENT OF NATURAL RESO U RCES TH E GEOLOGIC AND WATER RESOURC ES DIVISION THE GEOHYDROLOGY OF BEN HILL, IRWIN, TIFT, TURNER, AND WORTH COUNTIES, GEORGIA THOMAS W. WATSON HYDROLOGIC ATLAS 2 SHEET 3 OF 3 32 39 23 36 33 30 21 22 26 24 35 48 I 3145' [ I ( <::'" ' \ \ \ I l :::> .J L, I \ I L_ r-L- I 3 130' ~ '--] 112 '....-- ' _ _ _ _ .J ~ I I33 I I 2.7 I I 35 I 33 36 I I- - - 112 ' 'v- \) 29, ~FT COUNT Y 'v1 5 34 9 13 \ 24 90 \ 90 I \ __5_o _ ,1-1-l 39 ( 1 IRWIN COUNTY 46 26 I Fitzgerald 45 I I 47 r- _j I ,_/ !zl 8! .........- - i - - - - - - { 3 2 ~~ 0:: =>I ~ ---, 38 32. rB.EN=HI-LL-C-OU-NT-Y - - 43 , IRWIN COUNTY j I I - _ _ r-' ' , ~ r_j Ocilla l_ 42 I 4 9 C---~ I I 51 \ 4 \ 16 II \ I ) I 42 I I j3 130' II \ I ar - - - - - ...._____ , ___ J IRWIN COUNTY ~ ------~ II_j3145' 47 t _ _ _ _ _ _ J _ _ __ ____. I I J 43 I 15 7 I I .28 '_j 20 I I 6 ,.-J rj 49 ,__I 51 WORTH . 22 CO-UN-TY- - - - , ~- I __L ___ - -TI-FT-C-OU-NTY- - -2. ,_ r jI - _r' , - - - - - -- - - - , - - - - - - - - - - , L- - - ' 8 3 30' 31 10 SCALE 1=250,000 '"-==r::=:E3:::=:JEolO=======:}'=:==_::=:==:==:==:==;=iJ:IO===:::====i"~=:==:==:==;;;=;~20 Statui~ Miles t:: B==0 B==~~~ 10 ==15 ~~~ 20 ==~ 25 ~~30 Kilometers Figure 6. Map showing Stiff Diagrams of selected wells in study area. 23 Identification number of well with Stiff Diagram 34 Id entification number of well 7 9 Concentration in Milliequivalents Per Liter 5 4 3 2. 0 2. 3 4 5 ~I~ ;;11----------I-+----+---.-+1------lK