Hydrogeology and water quality of the 

Upper Three Runs aquifer in the vicinity of the 

Gibson Road Landfill, Fort Gordon, Georgia, 

June–November 1999

by Sherlyn Priest and Kristen Bukowski McSwain

______________________________________________________________________________

U.S. Geological Survey

Water-Resources Investigations Report 02-4153

Prepared in cooperation with the

U.S. Department of the Army

Environmental and Natural Resources Management

Office of the U.S. Army Signal Center and Fort Gordon

Atlanta, Georgia

2002
For additional information, please write to:

State Representative

U.S. Geological Survey

3039 Amwiler Road, Suite 130

Atlanta, GA 30360-2824

http://ga.water.usgs.gov

U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

CHARLES G. GROAT, Director

Any use of trade, product, or firm names is for descriptive purposes

only and does not imply endorsement by the U.S. Government

Copies of this report can be purchased from:

U.S. Geological Survey

Branch of Information Services

Denver Federal Center

Box 25286

Denver, CO 80225-0286
Contents iii

CONTENTS

Page

ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Purpose and scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Description of Study Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Methods of Investigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Previous Investigations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Well-Naming System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

HYDROGEOLOGY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Geologic Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Irwinton Sand Member of the Dry Branch Formation . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Tobacco Road Sand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Hydrology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Upper Three Runs Aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

GROUND-WATER QUALITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Contaminant Concentration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Physical Processes Affecting Contaminant Movement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

REFERENCES CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
iv Contents

FIGURES

1 Gibson Road Landfill and drainages at Fort Gordon, Georgia, study area . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Aerial photograph of the Gibson Road Landfill, location of wells and geoprobe sites used to define 

the hydrogeology and water quality of the aquifer, and lines of geologic sections, Fort Gordon, Georgia 5

3 Generalized correlation of hydrologic and geologic units in east-central Georgia . . . . . . . . . . . . . . . . . . 9

4 Geologic sections A–A' and B–B' in the vicinity of Gibson Road Landfill, Fort Gordon, Georgia . . . . . . 10

5 Geologic sections C–C ' and D–D' in the vicinity of Gibson Road Landfill, Fort Gordon, Georgia . . . . . 11

6 Aerial photograph and approximate altitude of the top of the clay layer in the Irwinton Sand 

Member in the vicinity of the Gibson Road Landfill, Fort Gordon, Georgia. . . . . . . . . . . . . . . . . . . . . . . 13

7 Aerial photograph and approximate altitude of the water table in the vicinity of the Gibson Road 

Landfill, June 11, 1999, Fort Gordon, Georgia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

8 Aerial photograph and approximate altitude of the water table in the vicinity of the Gibson Road 

Landfill, November 8–11, 1999, Fort Gordon, Georgia. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

TABLES

1 Location, construction, and water-level data for wells and borings in the vicinity of the Gibson Road 

Landfill, Fort Gordon, Georgia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2 Organic compounds detected in monitoring wells in the vicinity of the Gibson Road Landfill, 

February 1998–September 1991), Fort Gordon, Georgia. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3 Selected trace elements detected in monitoring wells in the vicinity of the Gibson Road Landfill, 

February 1998–September 1911), Fort Gordon, Georgia. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4 Selected volatile organic compounds in water samples measured against a standard by portable gas 

chromatograph collected at geoprobe sites southeast of the Gibson Road Landfill, Fort Gordon, 

Georgia, November 1999 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

5 Gas measurements, pH, and specific conductance in water samples from wells and borings in the 

vicinity of the Gibson Road Landfill, Fort Gordon, Georgia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Vertical Datum

Sea Level: In this report, “sea level” refers to the National Geodetic Vertical 

Datum of 1929 (NGVD of 1929)—a geodetic datum derived from a general 

adjustment of the first-order level nets of both the United States and Canada, 

formerly called “Sea Level Datum of 1929.”

Horizontal Datum

Horizontal coordinate information is referenced to the North American Datum of 

1983 (NAD 83). Historical data collected and stored as North American Datum of 

1927 (NAD 27) have been converted to NAD 83 for use in this report.

Hydrogeology and Water Quality of the Upper Three Runs Aquifer ABSTRACT 1

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

HYDROGEOLOGY AND WATER QUALITY OF THE 

UPPER THREE RUNS AQUIFER IN THE VICINITY OF THE 

GIBSON ROAD LANDFILL, FORT GORDON, GEORGIA, 

JUNE–NOVEMBER 1999

By Sherlyn Priest and Kristen Bukowski McSwain

ABSTRACT

Fort Gordon military installation, a U.S. Department of 

the Army facility, is located in east-central Georgia 

southwest of Augusta. The military base operates a 

three-phase unlined landfill—Gibson Road Landfill— 

to store a variety of wastes. Phases I and II stored only 

household wastes, and these phases were discontinued 

during the mid–1990s. Fort Gordon currently (1999) 

operates Phase III of the landfill that stores only construction and demolition debris. Water-quality monitoring detected selected trace elements and organic 

compounds exceeding the maximum contaminant 

levels of the U.S. Environmental Protection Agency, 

National Primary Drinking Water Standards. The 

selected trace elements and organic compounds 

detected showed that contamination of ground water 

had occurred in the vicinity of the landfill. In 1999, 

the U.S. Geological Survey, in cooperation with the 

Environmental and Natural Resources Management 

Office of the U.S. Army Signal Center and Fort Gordon, Georgia, began an assessment of the hydrogeology and water quality in shallow ground water in the 

vicinity of the Gibson Road Landfill to delineate the 

extent of a ground-water contamination plume in the 

vicinity of the landfill.

Hydrogeologic units in the Augusta area include the 

Upper Three Runs aquifer, the Gordon aquifer, the 

Millers Pond aquifer, and the Dublin aquifer. Only the 

shallowest aquifer, Upper Three Runs, was penetrated 

during this study. The Upper Three Runs aquifer is 

composed of sediments of the Barnwell Group. Mostly, 

these sediments are highly permeable fine to medium, 

well-sorted sand with lenses of clay. 

Ground-water flow is from northwest to southeast and 

generally was unaffected by seasonal variation during 

the period of study (June–November 1999). Watertable altitudes in the landfill area for the study period 

ranged from 394 feet (ft) to 445 ft above sea level. 

Ground-water samples analyzed for organic compounds and selected trace elements by a U. S. Environmental Protection Agency (USEPA) approved 

statistical test revealed that increases in contaminant 

concentrations above the detection limits had occurred 

during March and September 1999 in five wells—one 

of which is located upgradient. These organic compounds, respective increases in concentration, and the 

wells in which they were detected are: methylene chloride—wells 28AA29 (24 parts per billion [ppb] and 46 

ppb), 28AA30 (86 ppb and 130 ppb), and 28AA31 (240 

ppb and 140 ppb); 1,1-dichloroethene—well 28AA31 

(10 ppb and 5.7 ppb); 1,1-dichloroethane— wells 

28AA30 (81 ppb and 140 ppb) and 28AA31 (200 ppb 

and 130 ppb); and 1,1,1-trichloroethane—well 

28AA31 (61 ppb and 37 ppb). Although in some wells 

the concentration decreased from March to September, 

the median concentrations were still higher in certain 

groups. Trace element compounds, their respective 

increases in concentration, and the wells in which they 

were detected are: chromium—well 28AA30 (1,190 

ppb), vanadium—well 28AA30 (104 ppb); barium—wells 28AA27 (42.2 ppb) and 28AA32 (140 

ppb), and beryllium—well 28AA30 (6.3 ppb). These 

increases occurred in September, with the exception of 
2 INTRODUCTION Hydrogeology and Water Quality of the Upper Three Runs Aquifer

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

chromium in well 28AA30, which occurred in March. 

Although a statistical test indicated increases in contaminant concentrations had occurred, water from 

wells 28AA27, 28AA30, 28AA31, and 28AA32 had a 

decrease in contaminant concentrations from February 

1998 to September 1999.

U.S. Environmental Protection Agency, National Primary Drinking Water Regulations Maximum Contaminant Levels (PMCLs), formerly (MCLs) were exceeded in water from four wells for organic compounds and in five wells by selected trace elements 

during the February 1998, March 1999, and September 1999 sampling periods. The concentrations for the 

following organic compounds and the associated wells 

are: methylene chloride (PMCL is 5 ppb)—wells 

28AA27 (February, 37 ppb; March, 24 ppb; and September, 9.6 ppb), 28AA29 (February, 20 ppb; March, 

24 ppb; and September, 46 ppb), 28AA30 (February, 

50 ppb; March, 86 ppb; and September, 130 ppb), and 

28AA31 (February, 330 ppb; March 240 ppb; and September, 140 ppb); vinyl chloride (PMCL is 2 ppb)— 

well 28AA29 (March, 3.6 ppb; and September, 4.4 

ppb); 1,1-dichloroethene (PMCL is 7 ppb)—wells 

28AA30 (March 10 ppb; and September, 17 ppb) and 

28AA31 (February, 13 ppb; and March, 10 ppb); and 

1,1,2-trichloroethane (PMCL is 5 ppb)—well 28AA30

(March, 33 ppb). Contaminant concentrations decreased in well 28AA31 from March to September 

1999; however, concentrations still exceeded the 

PMCL. The concentrations for the following selected 

trace elements exceeding PMCL and the associated 

wells during the sampling periods February 1998, 

March 1999, and September 1999 are: mercury 

(PMCL is 2 ppb)—well 28AA24 (September, 2.82 

ppb), well 28AA25 (February, 3.1 ppb; March, 2.11 

ppb; and September, 2.28 ppb), and well 28AA30 

(September, 2.82 ppb); arsenic (PMCL is 50 ppb)— 

well 28AA30 (February, 90 ppb; and September, 114 

ppb); thallium (PMCL is 2 ppb)—wells 28AA27 

(March, 2.08 ppb) and 28AA29 (February, 2.56); barium (PMCL is 2,000 ppb)—well 28AA30 (March, 

4,490 ppb); chromium (PMCL is 30 ppb)—well 

28AA30 (February, 630 ppb; and March, 1,190 ppb); 

and beryllium (PMCL is 4 ppb)—well 28AA30 (September, 6.3 ppb). Water from seven wells, three of 

which are upgradient of the landfill, contained organic 

compounds and/or selected trace elements exceeding 

PMCLs during the period February 1998 to September 

1999 according to private consultants. Contaminants 

present in upgradient wells most likely were caused by 

chemical dispersion, leachate migration, incorrectly 

defined landfill area, or natural ground-water flow 

beneath the landfill. 

INTRODUCTION

Fort Gordon military installation (Fort Gordon), a U.S. 

Department of the Army facility (Army), is located in 

east-central Georgia, about 10 miles (mi) southwest of 

Augusta, Ga. (fig. 1). In 1985, the Georgia Environmental Protection Division (GaEPD), Department of 

Solid Waste Management (DSWM), issued an operating permit for the Gibson Road Landfill facility (landfill). The landfill is located in the west-central part of 

Fort Gordon and currently (1999) is operating as an 

unlined landfill having three fill phases. Household 

wastes were stored during Phases I and II; however, 

these phases were discontinued in the mid–1990s. 

Phase III currently (1999) stores only construction and 

demolition debris.

As a requirement of the GaEPD operating permit, 

landfill personnel began conducting semiannual (twice 

a year) water-quality sampling at four ground-water 

monitoring wells and one surface-water outfall in 

1985. In 1995, a water-quality monitoring plan was 

written for the landfill increasing the number of monitoring wells to 10 and changing the sampling protocol 

to that specified by Federal regulations (U.S. Environmental Protection Agency, 2000a, b). Water samples 

from the wells were analyzed for selected volatile 

organic compounds, selected trace elements, and field 

properties in ground water (pH, specific conductance, 

and temperature). Beginning in 1994, various consultants of the Army analyzed water samples for selected 

trace elements and organic compounds because some 

of these constituents were detected previously at concentrations that exceeded the USEPA PMCLs (highest 

legally allowable level of a contaminant in drinking 

water) (U.S. Environmental Protection Agency, 2000c).

Since 1998, organic compound and selected trace elements concentration increases were detected in water 

samples from five wells (Brent Cortelloni, Environmental Management Associates, LLC, written commun. with Sherlyn Priest, Hydrologist, USGS, 1998 

and 1999). Four wells had concentration increases for 

volatile organic compounds and three wells had concentration increases for selected trace elements. In 
Hydrogeology and Water Quality of the Upper Three Runs Aquifer INTRODUCTION 3

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

June 1999, the U.S. Geological Survey (USGS), in 

cooperation with the Environmental and Natural 

Resources Management Office of the U.S. Army Signal Center and Fort Gordon, Georgia, began an assessment of hydrogeology at Fort Gordon and water quality 

in shallow ground water in the vicinity of the landfill.

Purpose and Scope

The purpose of this report is to increase the geohydrologic understanding in the vicinity of the Gibson Road 

Landfill, Fort Gordon, Georgia, to aid the Army in making sound environmental management decisions. This 

report describes the hydrogeology and water quality of 

shallow ground water in the landfill area, including the

• relation of the lithology, stratigraphy, and structure of the Upper Three Runs aquifer in the 

vicinity of the landfill to the regional hydrogeologic framework,

• configuration of the water table, and groundwater-flow directions at and near the landfill, 

and

• water quality of the Upper Three Runs aquifer 

downgradient from the landfill. 

The investigation covered the period June–November 

1999 and includes

• determination of water-bearing sediments by 

relating well construction to the hydrogeologic 

framework;

• geophysical logging of existing wells to verify 

well construction and delineate the local hydrogeologic framework;

• water-level measurements; 

• testing of monitoring wells for the presence of 

landfill gas; and 

• sampling of ground water using direct-push 

method—HydropunchTM (Edge and Cordry, 

1989) to penetrate and sample the shallow, 

water-bearing zone. 

Figure 1. Gibson Road Landfill and drainages at Fort Gordon, Georgia, study area.

Brier

Creek

Sandy Run Creek

Spirit Cree

So

k

uth Prong Creek

Boggy Gut Creek

Base from 1:100,000-scale

U.S. Geological Survey Digital Line Graph

32°18'45"

32°26'15"

82°18'45" 82°11'15"

GIBSON ROAD LANDFILL

EXPLANATION

FORT GORDON

COLUMBIA CO

MC DUFFIE

CO

MC DUFFIE

CO

RICHMOND CO

JEFFERSON CO

RICHMOND CO

BURKE CO

0 1 234

01234

5 MILES

5 KILOMETERS

N

Study

area

Augusta

Coastal Plain

GEORGIA

Piedmont

Blue Ridge

Cumberland

Plateau and

Valley and Ridge

Fall Line

88

20 520

1

78

221

223

78
4 INTRODUCTION Hydrogeology and Water Quality of the Upper Three Runs Aquifer

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

Description of Study Area

Fort Gordon (fig. 1) is located in the Coastal Plain 

physiographic province in northwestern Richmond 

County, southwest of Augusta, Georgia, and in small 

parts of adjacent counties of Columbia, Jefferson, 

McDuffie, and Warren. Fort Gordon is located near the 

Fall Line (Clark and Zisa, 1976)—a transition zone 

between the Coastal Plain and Piedmont physiographic provinces (fig. 1). The general topography 

along the Fall Line is typified by rolling hills, with 

some rock outcroppings in stream valleys. Topographic relief at Fort Gordon is moderate; minimum 

altitude is 225 ft above sea level to the east, and maximum altitude is about 475 ft to the northwest.

The climate of the Augusta area in eastern Georgia is 

humid subtropical, characterized by hot, wet summers 

and mild, dry winters. The average daily low temperature is about 35 degrees Fahrenheit (°F) in the winter, 

and the average daily high temperature is about 90°F 

in the summer. In 1999, the total precipitation recorded 

at Augusta Bush Field Airport was 36.74 inches 

(National Oceanic and Atmospheric Administration, 

1999). Based on the 30-year normal (1961–90), average rainfall in the Augusta area is about 46 inches and 

snowfall is rare (National Oceanic and Atmospheric 

Administration, 1999). 

The landfill is an unlined facility that is owned and 

operated by the Army to serve Fort Gordon. The landfill is located in the west-central part of Fort Gordon 

and encompasses an area of about 35 acres (figs. 1 and 

2). The landfill is on the southern flank of a ridge east 

of Sandy Run Creek. The area surrounding the site is 

heavily wooded, with a few small drainage channels 

leading to perennial streams. The only surface-water 

body onsite is a constructed sediment pond (fig. 2) in 

the southeastern part of the landfill. Local topography 

slopes primarily to the southeast; however, the topography near the southwestern part of the landfill slopes 

to the southwest. The entire watershed of the site 

drains to Sandy Run Creek, which crosses Gibson 

Road about 0.7 mi to the west. Runoff is to the southwest to Sandy Run Creek and to the southeast to an 

unnamed tributary of Sandy Run Creek. Although 

streams are not directly adjacent to the landfill, a line 

of exposed ground-water seeps are located about 0.25 

mi to the southeast.

Methods of Investigation

A review of available hydrogeologic data specific to 

the landfill (mostly data collected by the Army) and 

general information concerning the geology and 

hydrology of the Augusta, Ga., area was conducted 

early in 1999; these data are incorporated into this 

report. Within the study area, the Army installed 10 

monitoring wells prior to this study to monitor groundwater contaminants. Historical data from these 10 

wells include well construction, well drilling, and 

water-quality characteristics. Well locations are shown 

in figure 2, and construction data are listed in table 1. 

Three wells were designated as upgradient (28AA24, 

28AA25, and 28AA27), two as midgradient (28AA31 

and 28AA34), and five as downgradient (28AA28, 

28AA29, 28AA30, 28AA32, and 28AA33) (fig. 2). 

Screening for landfill gas in ground water was conducted in September 1999 to determine if migrating 

landfill gas could be the source of volatile organic 

compounds detected at low concentrations in samples 

from upgradient wells. Landfill gas consists mainly of 

methane and carbon dioxide with traces of volatile 

organic compounds, sulfur dioxide, and hydrogen sulfide. Organic compounds with high vapor pressure 

could comigrate with landfill gas to contaminate 

upgradient or midgradient wells. The wells were 

screened for landfill gas using the following procedure. In the late morning, each well was plugged using 

an unvented solid well cap. After 4 hours, the solid cap 

was removed and air inside the well was immediately 

sampled and analyzed using a portable gas detector 

calibrated to methane gas. The oxygen level and percentage of the lower explosive limit of methane gas 

contained in the air were recorded and a vented cap 

reinstalled.

To better define site hydrogeology, geophysical logs 

were run in October 1999 in each of the 10 monitoring 

wells that surround the landfill. Natural-gamma and 

electromagnetic-conductivity logs were run in each 

well to verify well construction and to help define the 

shallow hydrogeologic framework. Additional geologic data (depth to confining clay layer) were collected in November 1999 using direct-push methods 

(geoprobe). Locations of 10 direct-push sites are 

shown in figure 2, and sampling depths are listed in 

table 1.
Hydrogeology and Water Quality of the Upper Three Runs Aquifer INTRODUCTION 5

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

Figure 2. Aerial photograph of the Gibson Road Landfill, location of wells and geoprobe

sites used to define the hydrogeology and water quality of the aquifer, and lines of 

geologic sections, Fort Gordon, Georgia.

500 FEET

100 METERS

0

0

250

50

N

A

A'

B

B'

C

C'

D

D'

LINE OF GEOLOGIC SECTION—Sections shown in figures 4 and 5

CONSTRUCTED SEDIMENT POND

WELL AND NUMBER

GEOPROBE SITE AND NUMBER

EXPLANATION

A A'

Base from U.S. Geological Survey

Blythe 1:100,000-scale digital orthophoto

28AA25

28AA24

28AA27

28AA29

28AA30

28AA31

28AA32

28AA33

28AA34

28AA34

28AA28

28AA35

28AA36

28AA37

28AA38

28AA39

28AA40

28AA41

28AA42 28AA43

28AA44

28AA35
6 INTRODUCTION Hydrogeology and Water Quality of the Upper Three Runs Aquifer

 in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

Table 1. Location, construction, and water-level data for wells and borings in the vicinity of the Gibson Road Landfill, Fort Gordon, Georgia[—, data not available; np, not penetrated; italic, geoprobe]

Well or boring

number

(see fig. 2) Latitude Longitude

Altitude (feet, above sea level) Water level

Land

surface

Top of screen

or sample

elevation

Bottom of

screen

Tobacco Road

Formation/Irwinton

 Sand Member contact

Confining

clay

penetrated

June

1999

November

 1999

28AA24 38°22'09" 82°14'42" 494.33 446.33 436.33 447 441 441.29 441.2428AA25 33°22'19" 82°14'29" 488.77 446.77 436.77 447 441 445.60 445.5328AA27 33°22'12" 82°14'37" 491.50 446.50 436.50 448 442 444.19 444.3828AA28 33°22'00" 82°14'39" 487.95 419.95 409.95 423 416 414.27 414.9128AA29 33°22'03" 82°14'34" 460.34 433.34 423.34 436 430 426.68 426.8028AA30 33°22'09" 82°14'28" 470.19 433.19 423.19 428 np 428.40 430.5128AA31 33°22'08" 82°14'27" 481.95 439.95 429.95 443 438 440.80 440.3628AA32 33°22'02" 82°14'29" 454.57 430.57 420.57 433 n p 427.54 429.6728AA33 33°22'03" 82°14'36" 474.16 427.16 417.16 431 424 425.15 425.5728AA34 33°22'01" 82°14'41" 492.11 438.11 428.11 440 np 434.16 434.4128AA35 33°22'05" 82°14'30" 454.62 428.57

—

— np

— 428.57

28AA36 33°22'06" 82°14'29" 460.41 431.15

—

— 423

— 431.15

28AA37 33°22'07" 82°14'27" 468.25 425.39

—

— 424

— 425.45

28AA38 33°22'08" 82°14'24" 467.67 419.42

—

— 417

— 419.42

28AA39 33°22'06" 82°14'25" 453.98 421.28

—

— 408

— 421.28

28AA40 33°22'04" 82°14'25" 448.07 417.37

—

— 409

— 417.37

28AA41 33°22'04" 82°14'26" 445.48 419.34

—

— 416

— 419.34

28AA42 33°22'04" 82°14'22" 442.49 417.46

—

— 403

— 417.46

28AA43 33°22'03" 82°14'20" 426.83 390.33

—

— 387

— 394.15

28AA44 33°22'02" 82°14'22" 425.43 412.58

—

— 400

— 412.58
Hydrogeology and Water Quality of the Upper Three Runs Aquifer INTRODUCTION 7

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

Ten sites were selected to measure volatile organic 

compounds (VOCs) in ground-water samples using a 

direct-push sampling method—HydropunchTM (Edge 

and Cordry, 1989). A direct-push sampling tool is a 

device made of 1-inch diameter stainless-steel drive 

pipe and screen. Teflon® tubing was used to collect inplace ground-water samples without installing a monitoring well. To collect a water sample, the drive pipe 

is pushed through soil to the desired depth. Soil and 

water are prevented from entering because the pipe 

remains in a closed position. When the desired sampling depth is reached, the drive pipe is retracted to 

expose a screen, allowing ground water to flow into 

the screen where water is collected through Teflon® 

tubing with a peristaltic pump into glass bottles with a 

septum top. Water samples collected were immediately analyzed onsite for VOCs (benzene, cis-1,2-

dichloroethylene, m-xylene, tetrachloroethene, toluene, trans-1,2-dichloroethylene, trichloroethylene, and 

vinyl chloride) using a portable gas chromatograph. 

Quality control samples included duplicates and 

equipment blanks. After analysis, each direct-push site 

was abandoned by filling the hole with bentonite. All 

equipment was decontaminated before moving to the 

next location by removing the old plastic sleeve that 

collected the sample and replacing it with a new one. 

The tools were washed with soapy water, rinsed with 

clean water, rinsed with alcohol, and then rinsed with 

clean water between each site. The equipment was 

steam cleaned before sampling and after all samples 

had been collected. 

Previous Investigations

Several hydrogeologic investigations have been conducted at the landfill. The most recent studies were conducted by a contractor to the U.S. Army (Joan A. Finkbeiner, G.N. Richardson and Associates, Inc., written 

commun. with Sherlyn Priest, Hydrologist, USGS, 

1995). These unpublished reports include site-specific 

geology, hydrology, and ground-water quality data collected in accordance with the site water-quality-monitoring plan written by G.N. Richardson and Associates,

Inc. (Joan A. Finkbeiner, written commun., 1995).

Prowell and others (1985) described regional Coastal 

Plain sediments along a geologic section from central 

Georgia into South Carolina; Huddlestun and Hetrick 

(1985) provided the initial definition of the Barnwell 

Group in east-central Georgia; Hetrick (1992) constructed a map showing surficial geology in the WrensAugusta area; and Huddlestun and Summerour (1996) 

evaluated the geology and stratigraphy of eastern 

Burke County, Ga. 

LeGrand and Furcron (1956) described the regional 

geology and ground-water resources of east-central 

Georgia; Vincent (1982) described the geohydrology 

of the Jacksonian aquifer in central and east-central 

Georgia; Gorday (1985) described the hydrogeology 

of Coastal Plain strata in Richmond and northern Burke

counties. Brooks and others (1985) described the hydrogeology of the Gordon aquifer system; and Clarke and 

others (1985) described the hydrogeology of the Dublin and Midville aquifer systems. Clarke and others 

(1994) and Leeth and others (1996) described geologic, hydrologic, and water-quality data at two wellcluster sites in Burke County; Summerour and others 

(1994) evaluated tritium concentrations in shallow 

ground water in Burke County; Clarke and West (1997)

described ground-water levels and stream-aquifer 

relations near the Savannah River site; and Falls and 

others (1997) described the hydrogeology of Cretaceous and Tertiary strata near the Savannah River site. 

Well-Naming System

In this report, wells inventoried by the USGS are 

named using a system based on USGS topographic 

maps. Each 7-1/2-minute topographic quadrangle map 

in Georgia has been assigned a number and letter designation beginning at the southwest corner of the 

State. Numbers increase eastward through 39, and letters advance northward through “Z,” then double-letter designations “AA” through “PP” are used. The 

letters “I,” “O,” “II,” and “OO” are not used. Wells 

inventoried in each quadrangle are numbered sequentially beginning with “1.” Thus, the eighth well inventoried in the Blythe quadrangle (designated as 28AA) 

is designated as well 28AA08.

Acknowledgments

The authors extend thanks to John B. Wellborne, U.S. 

Army Signal Center and Fort Gordon, for his cooperation. A special thanks is extended to Judith D. Scholz, 

formerly with the U.S. Geological Survey, who analyzed

water samples in the field. Appreciation also is extended

to the many consultants who provided data collected as 

part of the monitoring process at the landfill.
8 HYDROGEOLOGY Hydrogeology and Water Quality of the Upper Three Runs Aquifer

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

HYDROGEOLOGY

Hydrogeology of the Coastal Plain Province in the 

vicinity of Fort Gordon near Augusta, Ga., is described 

in the following sections. These sections define the 

geologic setting and the hydrogeologic units of the 

area surrounding the landfill. 

Geologic Setting

The landfill (fig. 1) is located in the Coastal Plain 

physiographic province of Georgia, and is underlain 

by sediments of Late Cretaceous through middle Tertiary age (fig. 3). These sediments unconformably 

overlie igneous and metamorphic rocks of Paleozoic 

age and consolidated beds of early Mesozoic age 

(Chowns and Williams, 1983). In this study, only sediments of the Eocene Barnwell Group were penetrated 

during drilling. The lithology of the Barnwell Group is 

predominantly quartz sand with lesser amounts of clay 

(kaolinite and montmorillonite), limestone, chert, and 

gravel. The quartz sand ranges from very fine to very 

coarse and may contain lenses of gravel. Maximum 

thickness of the Barnwell Group is about 200 ft in 

parts of southern Burke County and averages 100 ft 

thick or less in most places. The Barnwell Group thins 

from Burke County updip toward the Fall Line. The 

bottom of the Barnwell Group was not penetrated 

during drilling at the landfill, thus the thickness is 

unknown at this location. 

The Barnwell Group in the west Augusta area is divided

into the following formations and members (Huddlestun and Summerour, 1996): Utley Limestone Member 

of the Clinchfield Formation, Griffins Landing and 

Irwinton Sand Members of the Dry Branch Formation, 

and Tobacco Road Sand (fig. 3). Only sediments of the 

Irwinton Sand Member of the Dry Branch Formation 

and the Tobacco Road Sand were penetrated during 

drilling at the landfill in this study.

Irwinton Sand Member of the 

Dry Branch Formation

In this study, the deepest geologic formation penetrated 

in the area of the landfill was the Irwinton Sand Member of the Dry Branch Formation. The Irwinton Sand 

Member consists of loose, fine-to-medium, well-sorted,

thinly laminated quartz sand that contains lenses or 

local laterally extensive beds of montmorillonitic clay 

(Huddlestun and Summerour, 1996; LaMoreaux, 1946). 

The thickness of the Irwinton Sand Member in the 

vicinity of the landfill is unknown because the member 

was not fully penetrated by any of the wells at the site. 

All of the monitoring wells at the landfill are completed in this member (figs. 4 and 5, table 1). 

Laterally extensive clay in the Irwinton Sand Member 

beneath the landfill is shown on the geologic sections, 

which were compiled using borehole geophysical data 

from 7 of 10 wells (figs. 4 and 5). Borehole geophysical data indicate that near the bottom of each well that 

penetrates the top of the clay, electromagnetic conductivity is noticeably increased, which is typical of clay. 

Although a similar increase in natural gamma radiation for clay would be expected, only small increases 

were indicated on the natural gamma log. This subdued gamma-log response is interpreted as a montmorillonitic or kaolinitic clay that contains little naturally 

occurring gamma-emitting radioisotopes (such as 

potassium-40 and daughter products of the uranium 

and thorium decay series).

The thickness of laterally extensive clay where present 

appears to exceed 3 ft, although the clay was not fully 

penetrated during drilling. In wells 28AA30 and 

28AA32, the clay was not penetrated because the wells 

were either not deep enough or the clay bed is locally 

discontinuous. In well 28AA34, a blockage at 47 ft 

prevented logging below that depth. A map showing 

the approximate altitude of the top of the continuous 

clay layer is shown in figure 6; well and geoprobe data 

used to construct the map are listed in table 1. The altitude of the top of the clay ranges from 442 ft at well 

28AA27 to 387 ft at geoprobe 28AA43. 

Tobacco Road Sand

The Tobacco Road Sand overlies the Irwinton Sand 

Member and consists of fine-to-medium, well-sorted 

sand (Huddlestun and Summerour, 1996). The most 

characteristic lithology of the Tobacco Road Sand is a 

burrowed and bioturbated, massive-bedded, moderately to poorly sorted, medium- to coarse-grained, 

pebbly, weathered sand (Huddlestun and Summerour, 

1996). Strata are generally thin-bedded and contain 

thin layers of montmorillonite clay. The contact between the Tobacco Road Sand and the underlying 

Irwinton Sand Member is clearly indicated on borehole geophysical logs by an increase in natural gamma 

radiation and electromagnetic conductivity (figs. 4 and 

5). These increases probably represent a lag deposit of 
Hydrogeology and Water Quality of the Upper Three Runs Aquifer HYDROGEOLOGY 9

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

heavy minerals and reworked sediments from the 

underlying Irwinton Sand Member (David C. Prowell, 

U.S. Geological Survey, oral commun. with Kristen 

Bukowski McSwain, USGS, Hydrologist, October 

2000). Table 1 shows the altitude of the contact 

between the Irwinton Sand Member and the Tobacco 

Road Sand. At the landfill, the Tobacco Road Sand 

ranges in thickness from 65 ft at well 28AA28 to 22 ft 

at well 28AA32, with an average thickness of about 42 

ft (figs. 4 and 5). 

Figure 3. Generalized correlation of hydrologic and geologic units in

east-central Georgia (modified from Huddlestun and Summerour,

1996; Falls and others, 1997).

Lithology System

Series

Group

Formation/Member Hydrologic Units

Tobacco Road Sand

Lisbon Formation

Congaree Formation

Snapp Formation

Steel Creek Formation

Galliard Formation

COARSE SAND

MEDIUM SAND

MARL LIMESTONE

Marl and clay are

dotted where sandy CLAY

Black Mingo Formation

Utley Limestone Member

Clinchfield Formation

Confining

unit

Confining

unit

Confining

unit

Eocene

Tertiary

Barnwell Group Claiborne Group

Paleocene

Oconee Group

Upper

Cretaceous

Cretaceous

Still Branch Sand

Upper Three

Runs aquifer

Gordon aquifer

Millers Pond aquifer

Dublin aquifer

Confining unit

Midville aquifer

EXPLANATION

Dry Branch Formation
10 HYDROGEOLOGY Hydrogeology and Water Quality of the Upper Three Runs Aquifer

 in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia Figure 4. Geologic sections 

A

–

A' and 

B–

B' in the vicinity of Gibson Road Landfill, Fort Gordon, Georgia

(boring lithologies from G. N. Richardson and Associates, Water Quality Monitoring Plan, July 1995).

28AA24

28AA25

28AA27

28AA28

28AA29

28AA30

28AA32

28AA33

0

40

80

120

160

0

40

80

120

160

0

40

80

120

160

0

40

80

120

160

0

40

80

120

160

0

40

80

120

160

0

40

80

120

160

0

40

80

120

160 LITHOLOGY

–5

0

5

10

15

20

25

–5

0

5

10

15

20

25

–5

0

5

10

15

20

25

–5

0

5

10

15

20

25

–5

0

5

10

15

20

25

–5

0

5

10

15

20

25

–5

0

5

10

15

20

25

–5

0

5

10

15

20

25

A

Southwest Northeast Southwest Northeast

A' B B'

500 FEET

100 METERS

00

250

50

Tobacco

Road

Sand

BEND IN

SECTION

BEND IN

SECTION

BEND IN

SECTION

BEND IN

SECTION

Irwinton

Sand

Member

Sand

Sandy clay Clay

EXPLANATION

Tobacco Road Sand

Irwinton Sand Member

Land surface

NATURAL GAMMA—In American Petroleum Institute UnitsSPECIFIC CONDUCTANCE—At 25 degrees Celsius, in microsiemens per centimeterGEOLOGIC CONTACTWATER LEVEL—Measured in November 1999

Sandy silt

VERTICAL SCALE

GREATLY EXAGGERATED

DATUM IS SEA LEVEL

500490480470460450440430420410

490480470450440430

ALTITUDE, IN FEET ABOVE SEA LEVEL

500460
Hydrogeology and Water Quality of the Upper Three Runs Aquifer HYDROGEOLOGY 11

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia 

Figure 5. Geologic sections 

C–

C ' and 

D–

D' in the vicinity of Gibson Road Landfill, Fort Gordon, Georgia

(boring lithologies from G. N. Richardson and Associates, Water Quality Monitoring Plan, July 1995).

28AA31

28AA34

28AA24

28AA25

28AA28

28AA30

500 FEET

100 METERS

00

250

50

Tobacco

Road

Sand

Land surface

Irwinton

Sand

Member

Tobacco

Road

Sand

Irwinton

Sand

Member

490480470450440430420410

ALTITUDE, IN FEET ABOVE SEA LEVEL

500

460

500490480470460450440430420410

EXPLANATION

DATUM IS SEAL LEVEL

Sand

Sandy clay Clay NATURAL GAMMA—In American Petroleum Institute Units

SPECIFIC CONDUCTANCE—At 25 degrees Celsius, in microsiemens per centimeter

GEOLOGIC CONTACTWATER LEVEL—Measured in November 1999 Sandy silt

BEND IN

SECTION

BEND IN

SECTION

VERTICAL SCALE

GREATLY EXAGGERATED

0

40

80

120

160

0

40

80

120

160

0

40

80

120

160

0

40

80

120

160

0

40

80

120

160

0

40

80

120

160

LITHOLOGY

–5

0

5

10

15

20

25

–5

0

5

10

15

20

25

–5

0

5

10

15

20

25

–5

0

5

10

15

20

25

–5

0

5

10

15

20

25

–5

0

5

10

15

20

25

C'

C

North South North South

D D'

28AA31

28AA34

28AA24

28AA25

28AA28

28AA30

500 FEET

100 METERS

00

250

50

Tobacco

Road

Sand

Land surface

Irwinton

Sand

Member

Tobacco

Road

Sand

Irwinton

Sand

Member

490480470450440430420410

ALTITUDE, IN FEET ABOVE SEA LEVEL

500

460

500490480470460450440430420410

EXPLANATION

DATUM IS SEAL LEVEL

Sand

Sandy clay Clay NATURAL GAMMA—In American Petroleum Institute Units

SPECIFIC CONDUCTANCE—At 25 degrees Celsius, in microsiemens per centimeter

GEOLOGIC CONTACTWATER LEVEL—Measured in November 1999 Sandy silt

BEND IN

SECTION

BEND IN

SECTION

VERTICAL SCALE

GREATLY EXAGGERATED

0

40

80

120

160

0

40

80

120

160

0

40

80

120

160

0

40

80

120

160

0

40

80

120

160

0

40

80

120

160

LITHOLOGY

–5

0

5

10

15

20

25

–5

0

5

10

15

20

25

–5

0

5

10

15

20

25

–5

0

5

10

15

20

25

–5

0

5

10

15

20

25

–5

0

5

10

15

20

25

C'

C

North South North South

D D'
12 GROUND-WATER QUALITY Hydrogeology and Water Quality of the Upper Three Runs Aquifer

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

Hydrology

Hydrogeologic units in the Augusta area include the 

Upper Three Runs aquifer, the Gordon aquifer, the 

Millers Pond aquifer, the Dublin aquifer, and the Midville aquifer. In this report, only the shallowest aquifer—the Upper Three Runs aquifer—is described. For 

a complete discussion of the other units, see Clarke 

and others (1985), Brooks and others (1985), and Falls 

and others (1997).

Upper Three Runs Aquifer

In the area of the landfill, the Upper Three Runs aquifer 

is comprised of quartz sand, calcareous sand, and limestone of the Barnwell Group (fig. 3) (Summerour and 

others, 1994; Clarke and West, 1997). Mostly, these 

sands are highly permeable; however, clay beds and 

lenses within the Irwinton Sand Member of the Dry 

Branch Formation produce locally perched water tables 

(Huddlestun and Summerour, 1996). There is some 

evidence that the water-bearing zone tapped by monitoring wells at the landfill is perched on the clay unit in 

the Irwinton Sand Member. Water-table contours follow the dip of the lower clay layer (figs. 6, 7, and 8) and 

are coincident with the general land-surface topography. 

Ground-water flow directions and gradients were evaluated by constructing maps of the water table using 

water-level data collected from 10 monitoring wells 

near the landfill during June and November 1999 (figs. 

7 and 8, respectively). For both periods, ground water 

flowed from recharge areas to the northwest where 

water levels are higher to discharge areas to the southeast where water levels are lower (figs. 7 and 8).

For the period June to November 1999, the ground-waterflow direction generally was unaffected by seasonal 

water-level variations. Based on data from the 10 monitoring wells, the altitude and configuration of the water-table 

surface in June 1999 is similar to that in November 1999. 

In June 1999, the water-table altitude in the landfill area 

ranged from about 414 ft at well 28AA28 to about 445 ft

at well 28AA25 (fig. 7, table 1). In November 1999, 

water-table altitudes ranged from about 415 ft at well 

28AA28 to about 445 ft at well 28AA25 (fig. 8, table 1).

Geologic sections (figs. 4 and 5) and a structure-contour map of the top of the clay in the Irwinton Sand 

Member (fig. 6) indicate that the water table is parallel 

to the dip of the clay. Water levels generally are 3 ft 

above the top of the clay; and the water table follows 

the dip of the clay, which has the same general slope 

as the surface topography. 

Data are insufficient to confirm whether the monitoring 

wells are completed in a perched zone. Construction of one or more wells downgradient of the landfill 

that penetrate the clay and terminate in the layer 

beneath the sand would help confirm perched conditions. If this layer is dry (unsaturated zone beneath a 

water-bearing zone), then the zone above may be 

perched. Also, the landfill is constructed near a topographic high; and, typically, topographic highs coincide with ground-water highs since ground water is a 

subdued replica of surface topography (Heath, 1983).

GROUND-WATER QUALITY

Selected trace elements and organic compounds have 

been detected in the ground water adjacent to the landfill, including upgradient wells. The origin of the contaminants in the upgradient wells is undefined; however, several physical processes have been identified as 

possible explanations for contamination in upgradient 

wells.

Contaminant Concentration

Nine ground-water sampling events were conducted at 

the landfill between June 1994 and September 1999 

(Brent Cortelloni, Environmental Management Associates, LLC, written commun. with Sherlyn Priest, Hydrologist, USGS, 1999). Environmental Management 

Associates, LLC (Brent Cortelloni, written commun., 

1999) conducted semiannual ground-water monitoring 

at the landfill from February 1998 to September 1999.

GaEPD (1997) regulations require statistical methods 

as the basis for investigating potential environmental 

impacts in a waste-disposal-facility operation. Groundwater monitoring results were evaluated using an analysis of variance (ANOVA) statistical method (GRITS/

STAT)—USEPA statistical computer program (1997). 

Consultants performed nonparametric ANOVA tests 

based on the percentage of nondetects and/or the nonnormality of the data. Army consultants used the 

Kruskal-Wallis (K-W) statistical test to determine if a 

statistically significant increase in contaminant concen-
Hydrogeology and Water Quality of the Upper Three Runs Aquifer GROUND-WATER QUALITY 13

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

tration above background had occurred. The ANOVA 

tests compared selected trace elements concentrations 

in water from the midgradient and downgradient monitoring wells to concentrations in the upgradient wells.

For the organic compound statistical tests, background 

concentrations were set at the detection limit for the 

associated compound. Organic concentrations were 

compared with those at the detection limit. 

Figure 6. Aerial photograph and approximate altitude of the top of the clay layer in the

Irwinton Sand Member in the vicinity of the Gibson Road Landfill, Fort Gordon, Georgia.

28AA35

28AA36 28AA37

28AA38

28AA39

28AA40

28AA41

28AA42 28AA43

28AA44

28AA44

N

500 FEET

100 METERS

0

0

250

50

420

440

435

430

425

420

STRUCTURE CONTOUR—Shows approximate altitude

of the top of the clay layer in the Irwinton Sand Member.

Contour interval 5 feet. Datum is sea level

WELL AND NUMBER

GEOPROBE SITE AND NUMBER

EXPLANATION

28AA28

28AA25

28AA25

28AA24

28AA27

28AA29

28AA30

28AA31

28AA32

28AA33

28AA34

Base from U.S. Geological Survey

Blythe 1:100,000-scale digital orthophoto
14 GROUND-WATER QUALITY Hydrogeology and Water Quality of the Upper Three Runs Aquifer

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

Figure 7. Aerial photograph and approximate altitude of the water table in the vicinity

of the Gibson Road Landfill, June 11, 1999, Fort Gordon, Georgia.

WATER-TABLE CONTOUR—Shows approximate altitude of water

 table, June 11, 1999. Contour interval 5 feet. Datum is sea level

WELL AND NUMBER

GENERALIZED DIRECTION OF GROUND-WATER FLOW

EXPLANATION

Base from U.S. Geological Survey

Blythe 1:100,000-scale digital orthophoto

430

N

500 FEET

100 METERS

0

0

250

50

440

445

435

430

425

420

415

28AA24

28AA25

28AA27

28AA28

28AA29

28AA30

28AA31

28AA32

28AA33

28AA34

28AA34
Hydrogeology and Water Quality of the Upper Three Runs Aquifer GROUND-WATER QUALITY 15

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

Figure 8. Aerial photograph and approximate altitude of the water table in the vicinity of the

Gibson Road Landfill, November 8–11, 1999, Fort Gordon, Georgia.

28AA35

28AA36

28AA37

28AA38

28AA39

28AA40

28AA41

28AA42 28AA43

28AA44

28AA44

N

500 FEET

100 METERS

0

0

250

50

420

445

440

435

430

425

420

415

WATER-TABLE CONTOUR—Shows approximate altitude

 of water table during November 8–11, 1999. Contour

 interval 5 feet. Datum is sea level

WELL AND NUMBER

GENERALIZED DIRECTION OF GROUND-WATER FLOW

GEOPROBE SITE AND NUMBER

EXPLANATION

28AA28

28AA25

28AA24

28AA27

28AA29

28AA30

28AA31

28AA32

28AA33

28AA34

28AA25

Base from U.S. Geological Survey

Blythe 1:100,000-scale digital orthophoto
16 GROUND-WATER QUALITY Hydrogeology and Water Quality of the Upper Three Runs Aquifer

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

Environmental Management Associates, LLC (Brent 

Cortelloni, written commun., 1999) reported, based on 

statistical analysis, increases in concentration of 

organic compounds and selected trace elements 

occurred during March and September 1999 in five 

monitoring wells adjacent to the landfill. The majority 

of the concentration increases (downgradient and 

midgradient) were in ground water from monitoring 

wells 28AA30 and 28AA31, located in the southeast 

corner of the landfill. However, concentration increases also occurred in downgradient wells 28AA29 

and 28AA32, and in upgradient well 28AA27, even 

though the concentrations may have decreased over 

time. Organic compounds with concentration increases 

included 1,1-dichloroethane, 1,1-dichloroethene, 

1,1,1-trichloroethane, 1,1,2-trichloroethane, and 

methylene chloride (table 2). In well 28AA31, a 

decrease in concentration was noted for 1,1-dichloroethane, 1,1-dichloroethene, 1,1,1-trichloroethane, and 

methylene chloride; however, the concentrations are 

still statistically significant increases above the background. Concentrations of selected trace elements that 

also showed statistically significant increases included 

barium, beryllium, chromium, and vanadium (table 3).

To determine concentrations of chlorinated solvents 

downgradient of the landfill, screening was conducted 

at 10 geoprobe sites using a portable gas chromatograph. The sites are located beyond the cover of the 

landfill by as much as about 750 ft from the eastern 

edge of the landfill (fig. 2). At each of the 10 geoprobe 

sites, water samples were analyzed for the eight compounds in a mixed standard (methanol) (Supelco, 

1999) to calibrate the gas chromatograph, including 

benzene, cis-1,2-dichloroethylene, m-xylene, tetrachloroethene, toluene, trans-1,2-dichloroethylene, 

trichloroethylene, and vinyl chloride (table 4). These 

compounds are organic solvents that produce separate 

and distinct chemical signatures or “spikes” on a portable gas chromatograph. Because screening results 

are based on calibration to a standard (Supelco, 1999), 

sample results are reported in an amount relative to the 

chemical concentrations in the standard. If the gas 

chromatograph recorded a spike larger in a sample 

than in the standard, the constituent was assigned a 

value proportionally higher than the standard. If the 

gas chromatograph recorded a spike in a sample that 

was smaller than that produced by the standard, the 

constituent was given a proportionally lower value 

than the standard. If a spike was not detected, the 

constituent was considered to be a nondetect in the 

sample.

A sample from geoprobe 28AA37 close to wells 

28AA30 and 28AA31 had concentrations above the 

standard—most likely from leachate transport. Seven 

of the eight standard compounds were present in 

ground-water samples collected at geoprobe 28AA37 

(table 4). Only geoprobe 28AA41 appeared to be unaffected by contaminants from the landfill. Water-table 

maps (figs. 7 and 8) indicate that the ground-water 

flow direction near geoprobe 28AA37 and wells 

28AA30 and 28AA31 is to the southeast. Insufficient 

data are available to properly define the hydrologic 

system and assess the potential for future contaminant 

migration. Gas chromatograph screening at each of the 

10 geoprobe sites indicates that ground-water sites 

closest to wells 28AA30 and 28AA31 show substantial impacts on water quality (table 4). Seven of eight 

compounds analyzed were detected in ground-water 

samples collected from geoprobe 28AA37; and 9 of 

the 10 geoprobe sites indicate detections of organic 

compounds (table 4).

Selected trace elements in ground water at six wells 

and organic compounds at four wells exceeded the 

USEPA National Primary Drinking Water Regulations 

PMCL for organic compounds and selected trace 

elements (U. S. Environmental Protection Agency, 

2000c, d). Well 28AA30 had the most detections (a 

total of seven) of selected trace elements that exceeded 

PMCLs including: arsenic, barium, chromium, lead, 

mercury, thallium, and beryllium (table 3). Four 

wells—28AA27, 28AA29, 28AA30, and 28AA31— 

each had compounds that exceeded PMCLs for 

organic compounds (table 2). These compounds 

include methylene chloride, vinyl chloride, 1,1,2-

trichloroethane, and 1,1-dichloroethene. The three 

upgradient wells (28AA24, 28AA25, and 28AA27) 

each had trace elements (table 3) that exceeded 

PMCLs, and one well (28AA27) had an organic 

compound that exceeded a PMCL (table 2). 
Hydrogeology and Water Quality of the Upper Three Runs Aquifer GROUND-WATER QUALITY 17

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

Table 2. Organic compounds detected in monitoring wells in the vicinity of the Gibson Road Landfill, February 1998–

September 19991), Fort Gordon, Georgia

[—, data not available; PMCL, Primary Maximum Contaminant Level; nd(5), not detected at reporting level of 5 ppb; ppb, parts per 

billion; bold, exceeded PMCL; SVOC, semivolatile organic chemical; shaded, statistically significant increases above background]

Well 

number

Organic 

compounds

PMCL

(ppb)

February 1998

(ppb)

March1999

(ppb)

September 1999

(ppb)

28AA24 1,1-Dichloroethene 7 — nd(5) 5

Dichlorofluoromethane — 8 nd(5) nd(5)

Trichlorofluoromethane — 20 9.7 24

1,1-Dichloroethane — 6 13 24

1,1,1-Trichloroethane 200 15 44 5

28AA25 Diethylphthalate (SVOC) — 42 nd(10) —

28AA27 Chloroethane — 19 13 nd(10)

Methylene chloride 5 37 24 9.6

1,1,1-Trichloroethane 200 36 15 17

Tetrachloroethene 5 5 nd(5) —

Xylene 10,000 9 nd(5) 5.3

Diethylphthalate (SVOC) — 33 nd(10) —

28AA28 Diethylphthalate (SVOC) — 20 nd(10) —

28AA29 Methylene chloride 5 20 24 46

1,1-Dichloroethane — 19 23 33

Vinyl chloride 2 nd(2) 3.6 4.4

2,4-D (Herb.) 70 — — —

Chloroethane — — nd(10) 11

28AA30 1,1-Dichloroethene 7 6 10 17

Methylene chloride 5 50 86 130

1,1-Dichloroethane — 42 81 140

1,1,1-Trichloroethane 200 21 33 42

1,1,2-Trichloroethane 5 nd(5) 33 nd(5)

28AA31 Chloroethane — 25 28 20

1,1-Dichloroethene 7 13 10 5.7

Acetone — 270 nd(100) —

Methylene chloride 5 330 240 140

1,1-Dichloroethane — 210 200 130

1,1,1-Trichloroethane 200 75 61 37

Tetrachloroethene 5 5 nd(5) —

Xylene 10,000 14 12 9.7

28AA32 1,1-Dichloroethane — 22 nd(5) —

1,1,1-Trichloroethane 200 13 nd(5) —

28AA33 Diethylphthalate (SVOC) — 38 nd(10) —

Bis-(2-ethylhexyl) phthalate — — nd(20) 42

1)Table modified from Brent Cortelloni, Environmental Management Associates, LLC, written commun. 

with Sherlyn Priest, USGS, Hydrologist, 1998; 1999.
18 GROUND-WATER QUALITY Hydrogeology and Water Quality of the Upper Three Runs Aquifer

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

Table 3. Selected trace elements detected in monitoring wells in the vicinity of the Gibson Road Landfill, February 1998–

September 19911), Fort Gordon, Georgia

[—, data not available; PMCL, Primary Maximum Contaminant Level; nd(5), not detected at reporting level of 5 ppb; ppb, parts per billion; bold, 

exceeded PMCL; shaded; statistically significant increases above background; NTU, nephelometric turbidity units] 

Well

number

Selected trace

elements

PMCL

(ppb)

September 1999

Turbidity (NTUs)

February 1998 

(ppb)

March 1999 

(ppb)

September 1999 

(ppb)

28AA24 Barium 2,000 93 216 21.3 60.2

Chromium 100 — 15 nd(20) —

Copper — — 15 nd(20) —

Mercury 2 — 0.29 nd(0.5) 2.82

Vanadium — — 20 nd(50) —

Zinc — — 29 25.4 nd(20)

28AA25 Barium 2,000 4.27 101 nd(20) 21.4

Chromium 100 — 28 nd(20) —

Copper — — 10 nd(20) —

Mercury 2 — 3.1 2.11 2.28

Vanadium — — 48 nd(50) —

Zinc — — 740 nd(20) —

28AA27 Barium 2,000 94 260 127 42.2

Chromium 100 — 7 nd(0.5) —

Cobalt — — 28 nd(50) —

Mercury 2 — 0.35 nd(0.5) —

Thallium 2 — nd(2) 2.08 nd(2)

Zinc — — 24 nd(20) —

28AA28 Barium 2,000 26.6 118 nd(20) —

Chromium 100 — 26 nd(20) —

Copper — — 13 nd(20) —

Vanadium — — 21 nd(50) —

Zinc — — 30 nd(20) —

28AA29 Barium 2,000 0.1 43 164 89.4

Cobalt — — nd(20) 173 101

Mercury 2 — 1.17 nd(0.5) —

Sulfide — — nd(1,000) 1,000 —

Thallium 2 — nd(2) 2.56 nd(2)

Zinc — — nd(20) 27.5 26.1

28AA30 Arsenic 50 >200 90 nd(300) 114

Barium 2,000 — 1,530 4,490 —

Beryllium 4 — — nd(4) 6.3

Chromium 100 — 630 1,190 nd(20)

Lead 50 — 390 766 nd(10)

Mercury 2 — 0.71 nd(0.5) 2.28

Thallium 2 — nd(20) 10.2 nd(2)

Vanadium — — 1,090 2,090 104

Zinc — — 560 494 113

28AA31 Barium 2,000 9.01 40 34.5 27.9

Zinc — — nd(20) 21.8 nd(20)

28AA32 Barium 2,000 1.06 141 83.8 140

Chromium 100 — 15 nd(20) — Sulfide — — 1,800 nd(1000) — Vanadium — — 24 nd(50) —

28AA33 Barium 2,000 10.5 27 nd(20) 21.7

Cadmium 5 — 7 nd(5) — Lead 50 — 20 nd(10) —

28AA34 Barium 2,000 2.16 28 nd(20) —

1)Table modified from Brent Cortelloni, Environmental Management Association, LLC, written commun. with 

Sherlyn Priest, USGS, Hydrologist, 1998; 1999.
Hydrogeology and Water Quality of the Upper Three Runs Aquifer GROUND-WATER QUALITY 19

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

Table 4. Selected volatile organic compounds in water samples measured against a standard by portable gas 

chromatograph collected at geoprobe sites southeast of the Gibson Road Landfill, Fort Gordon, Georgia, November 1999

[nd, not detected; >, greater than; <, less than]

Geoprobe

number

Sample 

depth

(feet below

land surface)

Volatile organic compounds (in micrograms per liter)

Benzene Cis-1,2-

dichloroethylene

MXyleneTetrachloroethene Toluene Trans-1,2-

dichloroethylene

TrichloroethyleneVinyl

chloride

28AA35 26.05 nd nd nd nd nd >11 nd >15

28AA36 29.26 nd nd nd <50 <30 >11 <50 >15

28AA37 42.96 <30 <50 nd <50 <30 <11 <50 <15

28AA38 48.25 <30 <50 nd nd nd <11 <50 <15

28AA39 32.70 nd <50 nd nd nd <11 <50 <15

28AA40 30.70 nd <50 nd nd nd <11 nd <15

28AA41 26.14 nd nd nd nd nd nd nd nd

28AA42 25.03 nd <50 nd nd nd <11 nd <15

28AA43 36.50 nd <50 nd nd nd <11 <50 <15

28AA44 12.85 nd nd nd nd nd <11 nd <15

To determine if landfill gas is causing or contributing to 

organic compound concentration increases in monitoring wells, each monitoring well was plugged for at least 

4 hours, then the plug was removed and air measurements were made using a vapor meter (table 5). The 

vapor meter displays the lower explosive limits (LEL), 

in percent, of the gases detected and the percentage of 

oxygen present. The LEL for methane gas is 5 percent 

by volume methane in air. If landfill gases were not 

present in a well, one would expect the LEL percentage 

to be zero and the oxygen percentage to be 20.8 (under 

natural atmospheric conditions, methane gas is not 

detectable and the percentage of oxygen in the atmosphere is 20.8 percent). Two wells—28AA24 and 

28AA27 (figs. 7 and 8)—may contain landfill gas as 

indicated by reduced oxygen levels and an increase in 

LEL (table 5). These two wells are located close to a 

topographic high, which typically coincides with 

ground-water highs. In addition, these ground-water 

highs can move because of changes in water-level fluctuations. These movements can cause any number of 

perturbations to the water table, including short-term, 

and sometimes rapid, changes in gradient and flow 

direction. Nevertheless, the presence of landfill gas at 

well 28AA27 may be causing increases in organic 

compounds detected in water from the well. 

Elevated selected trace element concentrations may be 

caused by low pH and low dissolved oxygen concentrations (table 5), resulting in reducing conditions that 

favor movement of inorganic constituents into the 

water column. A decrease in pH and dissolved oxygen 

typically occur in landfills as a result of decomposition. 

The low pH causes metals such as beryllium, cadmium, 

chromium, and zinc to leach and eventually migrate. At 

the landfill, selected trace elements detected in upgradient wells likely are the result of normal ground-water 

flow or leachate migration. The landfill is located near 

a topographic high and consequently near a groundwater high. A seasonal variation in the water-table configuration could allow ground water to flow toward 

what is currently (1999) considered an upgradient 

direction. Furthermore, the top of the closed landfill 

phases (I and II) is topographically higher than the 

upgradient wells. As a result, leachate can migrate in 

all directions around the landfill including an upgradient direction. With time, the leachate can reach the 

water table and, depending on the direction and gradient of ground-water flow, contaminate the upgradient 

wells. Data are insufficient, however, to adequately 

define the long-term geometry of the water table 

beneath the landfill and surrounding area or the current 

direction of leachate migration.

Physical Processes Affecting 

Contaminant Movement

The presence of organic compounds in upgradient 

wells can be attributed to a number of physical processes. These physical processes include normal 

ground-water transport as a result a shifting hydraulic 

gradient, chemical dispersion (molecular diffusion), 

leachate migration, gas movement, incorrectly defined 
20 GROUND-WATER QUALITY Hydrogeology and Water Quality of the Upper Three Runs Aquifer

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

landfill area, or a combination of several of these physical processes. Although water-table maps (figs. 7 and 

8) do not show seasonal variation, it is possible that 

ground water flows in an upgradient direction during 

wet periods. Water-level data were collected during 

the dry period of the year and at the onset of the 2000 

drought. As a consequence, the hydraulic gradient is 

based on synoptic measurements collected during a 

very limited time period. Furthermore, upgradient 

wells are near a topographic high and ground-water 

flow direction beneath such a feature is highly variable. A ground-water high could cause short-term 

changes in gradient and flow direction during seasonal 

variation (Leeth, 1998). 

Table 5. Gas measurements, pH, and specific conductance in water samples from

wells and borings in the vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

[LEL, lower explosive limit; oC, degrees Celsius]

Digiflame 2000

gas measurement, 

9/27/1999 (percent)

August 1999

Well

 number

Specific conductance1)

(microsiemens per

centimeter at 25°C) pH1) LEL Oxygen

28AA24 36.0 18.0 150.0 5.02

28AA25 0.0 20.8 39.0 5.54

28AA27 52.0 12.9 188.0 7.32

28AA28 0.0 20.8 32.0 6.20

28AA29 0.0 20.8 755.0 4.78

28AA30 1.0 20.4 22.0 5.88

28AA31 3.0 20.2 72.0 5.61

28AA32 0.0 20.8 248.0 5.63

28AA33 0.0 20.8 61.0 5.96

28AA34 0.0 20.8 31.0 5.63

1)Specific conductance and pH data from Environmental Associates, LLC, written commun., Brent Cortelloni, 1999.

Contaminants may enter the soil in the absence of 

ground-water flow by chemical dispersion (molecular 

diffusion). In chemical dispersion, a high-concentration contaminant moves from its point of origin toward 

a point of lower concentration. In the case of upgradient dispersion, a landfill gas that is lighter than air 

(such as methane) could disperse vertically, especially 

if the soil upgradient from the point of origin is less 

consolidated than the soil downgradient from the point 

of origin. Because a landfill gas is lighter than air, the 

gas will rise and continue to disperse laterally.

Physical processes controlling gas movement through 

refuse and soil are complicated and beyond the scope 

of this report. However, gas generally moves along a 

path of least resistance through the refuse and adjacent 

soils. The movement can be accelerated along 

macropores, such as those paths along a plant-root 

system or animal burrows. The rate of movement is 

strongly influenced by weather conditions. When 

barometric pressure falls, gas tends to be forced out of 

a landfill and into the surrounding sediment. If a landfill is surrounded by a sandy soil—like the Gibson 

Road Landfill—the landfill gas will move more 

quickly through the soil. Clay caps, which are installed 

at completion of a landfill (for the purpose of excluding moisture infiltration and restricting leachate generation), tend to trap landfill gas.

Another physical process that could account for the 

presence of contaminants in upgradient wells is the 

movement of leachate containing organic and selected 

trace elements out of the landfill into the adjacent area. 

Most leachates are collected and treated; however, 

even under the best conditions, some leachates seep 

into the ground-water system. At the landfill, leachates 

are neither collected nor treated. Lastly, the subsurface 

landfill area may extend farther out than the surface 

expression of the landfill. If this is the case, the upgradient wells are actually landfill wells. Ground-water 

contamination near a landfill is a complicated problem. As a result, it is likely that the contamination 

observed in the landfill is a result of several sources. 

Insufficient data are available to properly identify the 

source of the contaminants in the upgradient wells.
Hydrogeology and Water Quality of the Upper Three Runs Aquifer SUMMARY AND CONCLUSIONS 21

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

SUMMARY AND CONCLUSIONS

Fort Gordon military installation, a U.S. Department 

of the Army facility, is located in east-central Georgia 

southwest of Augusta, Ga. The military base operates 

a three-phase unlined landfill—Gibson Road Landfill—to store a variety of wastes. Phases I and II stored 

only household wastes, and these phases were discontinued during the mid–1990s. Fort Gordon currently 

(1999) operates Phase III of the landfill that stores only 

construction and demolition debris.

Water-quality monitoring by the U.S. Army during a 

period of nearly 15 years detected selected trace elements and organic compounds exceeding the maximum contaminant levels of the U.S. Environmental 

Protection Agency, National Primary Drinking Water 

Standards. The selected trace element and organic 

compound detections showed that a ground-water contaminant plume was present in the vicinity of the landfill. In 1999, the U.S. Geological Survey, in 

cooperation with the Environmental and Natural 

Resources Management Office of the U.S. Army Signal Center and Fort Gordon, Ga., began an assessment 

of the hydrogeology and water quality in shallow 

ground water in the vicinity of the Gibson Road Landfill to delineate the extent of a ground-water contaminant plume at the landfill.

The Gibson Road Landfill is underlain by the Upper 

Three Runs aquifer, consisting of sediments of the 

Tobacco Road Sand and the Irwinton Sand Member of 

the Dry Branch Formation. All monitoring wells at the 

Gibson Road Landfill are completed within the Irwinton Sand Member. The overall thickness of the Irwinton Sand Member at the site is unknown because none 

of the wells fully penetrate the unit. All wells at the 

Gibson Road Landfill terminate within or above a laterally extensive clay with a thickness that exceeds 3 

feet (ft) where present within the Irwinton Sand Member. The Tobacco Road Sand overlies the Irwinton 

Sand Member, and ranges in thickness from 22 ft to 65 

ft, with an average thickness of 42 feet.

Ground-water flow was evaluated by constructing 

water-table maps in the area of the Gibson Road Landfill for June 1999 and November 1999. Ground-water 

flow generally is from northwest to southeast and was 

unaffected by seasonal water-level variations determined by short-term synoptic measurements made 

during the period of study. Wells 28AA24, 28AA25, 

and 28AA27 are upgradient with respect to the direction of flow. 

Some evidence exists that indicates the water-bearing 

zone tapped by monitoring wells at the Gibson Road 

Landfill may be perched on top of a clay unit in the 

Irwinton Sand Member. Water-table maps parallel the 

altitude of this clay unit and also parallel the land-surface topography. Insufficient data are available to 

determine whether the monitoring wells are completed 

in a perched zone. This determination would require 

construction of additional wells that terminate in the 

sand beneath the clay. If this layer is dry (unsaturated 

zone beneath water-bearing zone), then the zone may 

be considered perched. 

Several concentration increases of organic compounds 

and selected trace elements determined on the basis of 

statistical analysis were reported previously in five 

monitoring wells surrounding the Gibson Road Landfill. The concentration increases most likely were 

caused by chemical dispersion, leachate migration, 

incorrectly identified landfill area, or natural groundwater flow beneath the landfill. Gas chromatograph 

screening at 10 geoprobe sites indicates that groundwater sites closest to monitoring wells 28AA30 and 

28AA31 show significant impacts on water quality— 

most likely from leachate transport. Seven of eight 

organic compounds were detected in ground-water 

samples taken at geoprobe 28AA37. Nine of the 10 

geoprobe sites indicate some water-quality impact 

from leachate. Only geoprobe 28AA 41 appears to be 

unaffected by contaminants from the Gibson Road 

Landfill. Data from two upgradient wells—28AA24 

and 28AA27—indicate that these wells may be contaminated. Physical processes that may explain the 

contamination observed in these wells include the fact 

that the landfill is topographically higher than the surrounding area. Because the water table typically is a 

subdued replica of the surface topography, it is possible that ground water is flowing radially from the landfill, accounting for contaminant detection in upgradient wells. Although a clay layer is present 

beneath the landfill and the clay layer appears to dip in 

the general direction of the surface topography, data 

are insufficient to define the extent of the clay beyond 

the landfill cover. Consequently, a systematic 

approach to defining the ground-water flow in the area 

surrounding the landfill and the presence of a perched 

water table are needed to conclusively explain the 

observed contamination. 
22 REFERENCES CITED Hydrogeology and Water Quality of the Upper Three Runs Aquifer

in the Vicinity of the Gibson Road Landfill, Fort Gordon, Georgia

REFERENCES CITED

Brooks, Rebekah, Clarke, J.S., and Faye, R.E., 1985, Hydrogeology of the Gordon aquifer system of east-central Georgia: 

Georgia Geologic Survey Information Circular 75, 41 p.

Chowns, T.M., and Williams, C.T., 1983, Pre-Cretaceous rocks 

beneath the Georgia Coastal Plain - regional implications, 

in Gohn, G.S., ed., Studies related to the Charleston, South 

Carolina earthquake of 1886 - tectonics and seismicity: U.S. 

Geological Survey Professional Paper 1313-L, p. L1–L42.

Clark, W.Z., Jr., and Zisa, A.C., 1976, Physiographic map of 

Georgia: Georgia Geologic Survey, scale 1:2,000,000

Clarke, J.S., Brooks, Rebekah, and Faye, R.E., 1985, Hydrogeology of the Dublin and Midville aquifer systems of eastcentral Georgia: Georgia Geologic Survey Information Circular 

74, 62 p.

Clarke, J.S., Falls, W.F., Edwards, L.E., Frederiksen, N.O., 

Bybell, L.M., Gibson, T.G., and Litwin, R.J., 1994, Geologic, 

hydrologic, and water-quality data for a multi-aquifer system 

in Coastal Plain sediments near Millers Pond, Burke County, 

Georgia, 1992–93: Georgia Geologic Survey Information 

Circular 96, 34 p.

Clarke, J.S. and West, C.T., 1997, Ground-water levels, predevelopment ground-water flow, and stream-aquifer relations 

in the vicinity of the Savannah River Site, Georgia 

and South Carolina: U.S. Geological Survey Water-Resources 

Investigations Report 97-4197, 120 p.

Edge, R.W. and Cordry, Kent, 1989, The HydropunchTM: 

An in situ sampling tool for collecting ground water from 

unconsolidated sediments: Ground Water Monitoring 

Review, v. IX (3), p. 177–183.

Falls, W.F., Baum, J.S., Harrelson, L.G., Brown, L.H., and 

Jerden, J.L., Jr., 1997, Geology and hydrogeology of 

Cretaceous and Tertiary strata, and confinement in the vicinity 

of the U.S. Department of Energy Savannah River Site, South 

Carolina and Georgia: U.S. Geological Survey Water-Resources 

Investigations Report 97-4245, 125 p.

Georgia Environmental Protection Division, 1997, Solid Waste 

Management, Groundwater Monitoring and Corrective Action, 

Chapter 391-3-4-.14, revised August 1997.

Gorday, L.L., 1985, The hydrogeology of the Coastal Plain strata 

of Richmond and northern Burke Counties, Georgia: Georgia 

Geologic Survey Information Circular 61, 43 p.

Heath, R.C., 1983, Basic ground-water hydrology: U.S. 

Geological Survey Water-Supply Paper 2220, 84 p.

Hetrick, J.H., 1992, Geologic atlas of the Wrens-Augusta area: 

Georgia Geologic Survey Geologic Atlas 8, 3 sheets, scale 

1:100,000.

Huddlestun, P.F., and Hetrick, J.H., 1985, Upper Eocene 

stratigraphy of central and eastern Georgia: Georgia 

Geologic Survey Bulletin 95, 78 p.

Huddlestun, P.F., and Summerour, J.H., 1996, The lithostratigraphic framework of the uppermost Cretaceous and the lower 

Tertiary of eastern Burke County, Georgia: Georgia Geologic 

Survey Bulletin 127, 94 p.

LaMoreaux, P.E., 1946, Geology of Coastal Plain of east-central 

Georgia: Georgia Geologic Survey Bulletin 50, 26 p.

Leeth, D.C., 1998, Hydrogeology of the surficial aquifer in the 

vicinity of a former landfill, Naval Submarine Base Kings Bay, 

Camden County, Georgia: U.S. Geological Survey WaterResources Investigations Report 98-4246, 28 p.

Leeth, D.C., Falls, W.F., Edwards, L.E., Frederiksen, N.O., and 

Fleming, R.F., 1996, Geologic, hydrologic, and water-quality 

data for a multi-aquifer system in Coastal Plain sediments near 

Girard, Burke County, Georgia, 1993–95: Georgia Geologic 

Survey Information Circular 100, 26 p.

LeGrand, H.E., and Furcron, A.S., 1956, Geology and groundwater resources of central-east Georgia: Georgia Geologic 

Survey Bulletin 64, 164 p. 

National Oceanic and Atmospheric Administration, 1999, National 

Environmental Satellite, Data and Information Service, National 

Climatic Data Center, Climatological Data Annual Summary, 

Georgia, 1999: Asheville, NC., v. 103, no. 13, 29 p.

Prowell, D.C., Christopher, R.A., Edwards, L.E., Bybell, L.M., and 

Gill, H.E., 1985, Geologic section of the updip Coastal Plain 

from central Georgia and western South Carolina: U.S. 

Geological Survey Miscellaneous Field Studies Map MF-1737.

Summerour, J.H., Shapiro, E.A., Lineback, J.A., Huddlestun, P.F., 

and Hughes, A.C., 1994, An investigation of tritium in the 

Gordon and other aquifers in Burke County, Georgia: Georgia 

Geologic Survey Information Circular 95, 93 p.

Supelco, 1999, Certificate of Composition: Bellefonte, Pa., 

Supelco, 1 p. 

U.S. Environmental Protection Agency, 1997, A ground-water 

information tracking system with statistical analysis capability, 

version 5.0.

________, 2000a, Constituents for detection monitoring, U.S. 

Code of Federal Regulations, Title 40, Chapter 1, subchapter I, 

Appendix I of part 258, revised July 1, 2000.

________, 2000b, List of hazardous inorganic and organic 

constituents, 2000, U.S. Code of Federal Regulations, Title 40, 

Chapter 1, subchapter I, Appendix II of part 258, revised July 1, 

2000.

________, 2000c, Maximum contaminant levels (Subpart B of part 

141, National Primary Drinking-water Regulations): U.S. Code 

of Federal Regulations, Title 40, parts 100–149, revised as of 

July 1, 2000, p. 334–560.

________, 2000d, Maximum contaminant levels (Part 143, 

National Secondary Drinking-water Regulations): U.S. Code of 

Federal Regulations, Title 40, parts 100–149, revised as of July 

1, 2000, p. 612–614.

Vincent, H.R., 1982, Geohydrology of the Jacksonian aquifer in 

central and east-central Georgia: Georgia Geologic Survey 

Hydrologic Atlas 8, 3 sheets.