COVER PHOTO: Production well CHN-812 (324618080560900)

located near Colonial Lake in Charleston, South Carolina.

Photograph by Kevin J. Conlon
Hydrologic and Geochemical Evaluation of 

Aquifer Storage Recovery in the Santee 

Limestone/Black Mingo Aquifer, 

Charleston, South Carolina, 1998–2002

By Matthew D. Petkewich, David L. Parkhurst, Kevin J. Conlon, 

Bruce G. Campbell, and June E. Mirecki

U.S. Department of the Interior

U.S. Geological Survey

Prepared in cooperation with the

Charleston Commissioners of Public Works

Scientific Investigations Report 2004–5046
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

U.S. Geological Survey, Reston, Virginia: 2004

For sale by U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

For more information about the USGS and its products:

Telephone: 1-888-ASK-USGS

World Wide Web: http://www.usgs.gov/

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Petkewich, M.D., Parkhurst, D.L., Conlon, K.J., Campbell, B.G., and Mirecki, J.E., 2004, Hydrologic and geochemical 

evaluation of aquifer storage recovery in the Santee Limestone/Black Mingo aquifer, Charleston, South Carolina, 

1998–2002: U.S. Geological Survey Scientific Investigations Report 2004–5046, accessed May 24, 2004, at 

http://pubs.water.usgs.gov/sir2004-5046
 iii

Contents

Abstract. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Purpose and Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Previous Investigation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Description of Study Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Hydrogeologic Framework . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Tertiary Stratigraphy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Quaternary Stratigraphy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

X-ray Diffraction Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Hydrogeology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Hydrogeologic Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Well Construction and Instrumentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Geophysical Logging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Determination of Aquifer Hydraulic Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Aquifer Storage Recovery Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Geochemical Methods and Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Water-Quality Sampling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Recovery Efficiency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Chemical Composition of Waters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Trihalomethanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Chemical Reactions During Aquifer Storage Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Reactive-Transport Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Flow-Model Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Transport Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Chemical Reactions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Aquifer Storage Recovery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Recoverable Potable Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Effects of Injection on Porosity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Effects of a Regional Hydraulic Gradient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

References Cited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics 

measured in samples collected during aquifer storage recovery testing in Charleston, 

South Carolina. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Appendix 2. Dissolved trihalomethane and chloride concentrations measured in samples 

collected during cycle 4 of the aquifer storage recovery study in Charleston, 

South Carolina. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
iv 

Figures

1. Map showing study area and location of the aquifer storage recovery pilot study site 

and phase-II site, Charleston, South Carolina. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2. Chart showing generalized stratigraphic and hydrogeologic column based on core 

collected from observation well CHN-800 in Charleston, South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3. Graphs showing borehole geophysical logs for observation well CHN-811 at the aquifer 

storage recovery site, Charleston, South Carolina. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4. Map showing approximate potentiometric surface of the Floridan aquifer system 

prior to development in South Carolina. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

5. Map showing 1998 potentiometric surface of the Floridan aquifer system and 

Tertiary sand aquifer in South Carolina. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

6 – 18. Graphs showing:

6. Formation resistivity profiles collected in observation wells CHN-809 and CHN-810 

during the injection phase of cycle 2 of the aquifer storage recovery study 

in Charleston, South Carolina. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7. Electromagnetic flow-meter results while injecting freshwater into observation 

well CHN-809 during the aquifer storage recovery study in Charleston, South Carolina . . . . . . 14

8. Water-level altitudes in wells during the cycle-4 recovery phase of the aquifer 

storage recovery study in Charleston, South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

9. Water-level altitude and specific conductance at observation well CHN-809 during 

cycle 1 of the aquifer storage recovery study in Charleston, South Carolina. . . . . . . . . . . . . . . . . . 19

10. Water-level altitude and specific conductance at observation well CHN-809 during 

cycle 2 of the aquifer storage recovery study in Charleston, South Carolina. . . . . . . . . . . . . . . . . . 20

11. Water-level altitude, specific conductance, pH, and water temperature at 

observation well CHN-809 during cycle 3 of the aquifer storage recovery study 

in Charleston, South Carolina. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

12. Water-level altitude and specific conductance at observation well CHN-809 during 

cycle 4 of the aquifer storage recovery study in Charleston, South Carolina. . . . . . . . . . . . . . . . . . 22

13. Changes in specific conductance at observation well CHN-809 during the injection 

phases of the aquifer storage recovery study in Charleston, South Carolina . . . . . . . . . . . . . . . . . 23

14. Specific-conductance profiles collected in observation wells CHN-809 and CHN-810 

during cycles 3 and 4 of the aquifer storage recovery study in Charleston, 

South Carolina. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

15. Stiff diagrams depicting water quality in native ground water, injected water, 

late storage from observation well CHN-809, and early recovery from production 

well CHN-812 during cycle 3 of the aquifer storage recovery study in Charleston, 

South Carolina. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

16. Concentrations of selected ions relative to chloride concentrations during 

the cycle-3 recovery phase of the aquifer storage recovery study in Charleston, 

South Carolina. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

17. Chloroform and chloride concentrations in samples collected from observation 

wells CHN-809 and CHN-810 during cycle 4 of the aquifer storage recovery study 

in Charleston, South Carolina. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

18. Relative percentages of injected water in samples collected from observation 

wells CHN-809 and CHN-810 during cycle 4 of the aquifer storage recovery study 

in Charleston, South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

19. Schematic diagram showing grid used for simulations by which flow-model parameters 

were estimated from aquifer-test data at the aquifer storage recovery site in 

Charleston, South Carolina. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
 v

20 – 22. Graphs showing:

20. Measured drawdown data for November 2001 and June 1999 aquifer tests and 

simulated drawdowns using the best-fit parameters from the November 2001 

aquifer test at the aquifer storage recovery site in Charleston, South Carolina . . . . . . . . . . . . . . . 36

21. Measured water-level altitude in observation well CHN-809 and simulated 

water-level altitude calculated by using the selected flow-model parameters 

for the period of investigation at the aquifer storage recovery site in 

Charleston, South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

22. Measured chloride concentrations at observation well CHN-809 during injection, 

storage, and recovery in cycle 3 of the aquifer storage recovery study in 

Charleston, South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

23. Schematic diagram showing aquifer geometry used to simulate chloride transport for 

cycle 3 of the aquifer storage recovery study in Charleston, South Carolina . . . . . . . . . . . . . . . . . . . . . . . 39

24 – 28. Graphs showing:

24. Graph showing measured chloride concentrations and chloride concentrations 

simulated by using two 2-meter layers for each production zone and adjusted 

porosity and hydraulic conductivity during the aquifer storage recovery study in 

Charleston, South Carolina. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

25. Measured concentrations of major ions and pH for production well CHN-812 during 

cycle 3, and concentrations simulated by using the adjusted flow and transport 

parameters and a value of 0.1 equivalent per liter of water for the concentration 

of exchange sites during the aquifer storage recovery study in Charleston, 

South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

26. Measured concentrations of major ions and pH for observation well CHN-809 

during cycle 3 and concentrations simulated by using the adjusted flow and transport 

parameters and a value of 0.1 equivalent per liter of water for the concentration 

of exchange sites during the aquifer storage recovery study in Charleston, 

South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

27. Simulated concentrations of cations and amount of calcite reacted with distance 

from production well CHN-812 at the end of the cycle-3 injection period during 

the aquifer storage recovery study in Charleston, South Carolina. . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

28. Measured chloride concentrations for cycle 3 and simulated chloride 

concentrations during recovery following injection periods 1, 2, 4, and 8 times 

the 43-day injection for cycle 3 during the aquifer storage recovery study in 

Charleston, South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

29. Map showing extent of freshwater migration after 1, 10, and 100 years of injection at the 

aquifer storage recovery site, Charleston, South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

TABLES

1. Mineral abundances measured by quantitative X-ray diffraction microscopy and cation 

exchange capacity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2. Construction information for wells monitored during the aquifer storage recovery study 

in Charleston, South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

3. Estimated hydraulic characteristics of the Santee Limestone/Black Mingo aquifer based 

on the results of the June 1999 and November 2001 aquifer tests at the phase-II aquifer 

storage recovery site in Charleston, South Carolina. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4. Recovery efficiencies during the phase-II aquifer storage recovery study in Charleston, 

South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
vi 

5. Chemical composition of four water samples collected during cycle 3 of the aquifer 

storage recovery study in Charleston, South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

6. Mixing fraction and mole transfers that account for the water composition at observation 

well CHN-809 at the start of the cycle-3 recovery phase during the aquifer storage recovery 

study in Charleston, South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

7. Flow-model parameters fit from the June 1999 and November 2001 aquifer-test data collected 

at the phase-II aquifer storage recovery site in Charleston, South Carolina . . . . . . . . . . . . . . . . . . . . . . . . 35

8. Flow and transport model parameters selected for reactive-transport simulations during 

the aquifer storage recovery study in Charleston, South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
 vii

Conversion Factors and Datum 

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

meter (m) 3.281 foot (ft)

kilometer (km) 0.6214 mile (mi) 

Volume

cubic meter (m3) 35.31 cubic foot (ft3)

liter (L) 0.2642 gallon (gal) 

Flow rate

cubic meter per minute (m3/min) 35.31 cubic foot per minute (ft3/min)

liter per second (L/s) 15.85 gallon per minute (gal/min) 

million liters per day (ML/d) 0.2642 million gallons per day (Mgal/d)

Mass

gram (g) 0.03527 ounce avoirdupois (oz)

kilogram (kg) 2.205 pound avoirdupois (lb)

Pressure

kilopascal (kPa) 0.1450 pound-force per square inch (lbf/in2)

Hydraulic conductivity

meter per day (m/d) 3.281 foot per day (ft/d)

Transmissivity*

meter squared per day (m2/d) 10.76 foot squared per day (ft2/d)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F = (1.8 x °C) + 32

Datums:

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29). 

To convert to the North American Vertical Datum of 1988 (NAVD 88), subtract 0.3 meter from altitudes 

reported herein.

Horizontal coordinate information is referenced to the North American Datum of 1927 (NAD 27).

*Transmissivity: The standard unit for transmissivity is cubic meter per day per square meter times meter 

of aquifer thickness [(m3

/d)/m2]m. In this report, the mathematically reduced form, meter squared per day 

(m2

/d), is used for convenience.

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 25 °C).

Acronyms and Abbreviations:

ANC acid-neutralizing capacity

ASR aquifer storage recovery

bls below land surface

CaCO3 calcium carbonate

CCPW Charleston Commissioners of Public Works

CEC cation exchange capacity

CO2 carbon dioxide

d-1 per day

DOC dissolved organic carbon

EMFM electromagnetic flow meter

eq/L equivalents per liter

g/mol gram per mole
viii 

> greater than

HDPE high-density polyethylene

< less than

LPZ lower production zone

m-1 per meter

Ma million years before present

MCL maximum contaminant level

meq milliequivalents

m/m meter per meter

microgram per liter μg/L

milliequivalents per liter meq/L

milligram per liter mg/L

millimole per liter mmol/L

mol/L mole per liter

O2 dissolved oxygen

pH negative logarithm of hydrogen-ion activity

PHREEQC pH-REdox-EQuilibrium equations in the C programming language

PVC polyvinyl chloride

SI saturation index

SL/BM Santee Limestone/Black Mingo

SSE sum of squares error

TDS total dissolved solids

THM trihalomethanes

UPZ upper production zone

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey
Hydrologic and Geochemical Evaluation of Aquifer 

Storage Recovery in the Santee Limestone/Black Mingo 

Aquifer, Charleston, South Carolina, 1998–2002

By Matthew D. Petkewich1, David L. Parkhurst2, Kevin J. Conlon1, Bruce G. Campbell1, and June E. Mirecki3

Abstract

The hydrologic and geochemical effects of aquifer storage 

recovery were evaluated to determine the potential for 

supplying the city of Charleston, South Carolina, with large 

quantities of potable water during emergencies, such as 

earthquakes, hurricanes, or hard freezes. An aquifer storage 

recovery system, including a production well and three 

observation wells, was installed at a site located on the 

Charleston peninsula. The focus of this study was the 

23.2-meter thick Tertiary-age carbonate and sand aquifer of the 

Santee Limestone and the Black Mingo Group, the 

northernmost equivalent of the Floridan aquifer system. 

Four cycles of injection, storage, and recovery were 

conducted between October 1999 and February 2002. Each 

cycle consisted of injecting between 6.90 and 7.19 million liters 

of water for storage periods of 1, 3, or 6 months. The volume of 

recovered water that did not exceed the U.S. Environmental 

Protection Agency secondary standard for chloride 

(250 milligrams per liter) varied from 1.48 to 2.46 million 

liters, which is equivalent to 21 and 34 percent of the total 

volume injected for the individual tests. Aquifer storage 

recovery testing occurred within two productive zones of the 

brackish Santee Limestone/Black Mingo aquifer. The 

individual productive zones were determined to be 

approximately 2 to 4 meters thick, based on borehole 

geophysical logs, electromagnetic flow-meter testing, and 

specific-conductance profiles collected within the observation 

wells. A transmissivity and storage coefficient of 37 meters 

squared per day and 3 x 10-5, respectively, were determined for 

the Santee Limestone/Black Mingo aquifer. 

Water-quality and sediment samples collected during this 

investigation documented baseline aquifer and injected water 

quality, aquifer matrix composition, and changes in 

injected/aquifer water quality during injection, storage, and 

recovery. A total of 193 water-quality samples were collected 

and analyzed for physical properties, major and minor ions, and 

nutrients. The aquifer and treated surface water were sodiumchloride and calcium/sodium-bicarbonate water types, 

respectively. Forty-five samples were collected and analyzed 

for total trihalomethane. Total trihalomethane data collected 

during aquifer storage recovery cycle 4 indicated that this 

constituent would not restrict the use of recovered water for 

drinking-water purposes. Analysis of six sediment samples 

collected from a cored well located near the aquifer storage 

recovery site showed that quartz and calcite were the dominant 

minerals in the Santee Limestone/Black Mingo aquifer. 

Estimated cation exchange capacity ranged from 12 to 

36 milliequivalents per 100 grams in the lower section of the 

aquifer.

A reactive transport model was developed that included 

two 2-meter thick layers to describe each of the production 

zones. The four layers composing the production zones were 

assigned porosities ranging from 0.1 to 0.3 and hydraulic 

conductivities ranging from 1 to 8.4 meters per day. Specific 

storage of the aquifer and confining units was estimated to be 

1.5 x 10-5 meter-1. Longitudinal dispersivity of all layers was 

specified to be 0.5 meter. Leakage through the confining unit 

was estimated to be minimal and, therefore, not used in the 

reactive transport modeling. 

Inverse geochemical modeling indicates that mixing, 

cation exchange, and calcite dissolution are the dominant 

reactions that occur during aquifer storage recovery testing in 

the Santee Limestone/Black Mingo aquifer. Potable water 

injected into the Santee Limestone/Black Mingo aquifer 

evolved chemically by mixing with brackish background water 

and reaction with calcite and cation exchangers in the sediment. 

Reactive-transport model simulations indicated that the calcite 

and exchange reactions could be treated as equilibrium 

processes. 

Simulations with the calibrated reactive transport model 

indicated that approximately one-fourth of the total volume of 

water injected into the aquifer can be recovered as potable 

1U.S. Geological Survey, Columbia, South Carolina.

2

U.S. Geological Survey, Lakewood, Colorado.

3

U.S. Army Engineer Research and Development Center, Vicksburg, 

Mississippi.
2 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

water, regardless of the length of the injection period. 

Simulations also indicated that calcite dissolves near the 

injection well and precipitates where freshwater and brackish 

water mix during injection. However, the amounts of dissolved 

and precipitated calcite have a negligible effect on the aquifer 

porosity for simulated injection periods as long as 100 years and 

do not affect the flow of water during aquifer storage recovery. 

Finally, simulations indicated that the regional configuration of 

the potentiometric surface in the aquifer has a negligible effect 

on the storage of water. 

Introduction

Charleston, South Carolina, is located at the confluence of 

the Ashley, Cooper, and Wando Rivers near the Atlantic Ocean 

in the lower Atlantic Coastal Plain physiographic province 

(fig. 1). The area is characterized by wide estuaries bordered by 

extensive salt marshes, which are typical of coastal topography 

of low relief. The Charleston area is underlain by approximately 

760 meters (m) of Quaternary, Tertiary, and Upper Cretaceous 

sediments that compose five distinct aquifers separated by five 

confining units (Park, 1985; Campbell and others, 1997).

In 2000, the Charleston Commissioners of Public Works 

(CCPW ) provided retail and wholesale water to the Charleston 

metropolitan area, which includes portions of Charleston, 

Berkeley, and Dorchester Counties, and serves a population of 

about 420,000. CCPW provided water with an average flow of 

189 million liters per day (ML/d) and a peak flow of 340 ML/d 

(J.B. Cook, Charleston Commissioners of Public Works, 

written commun., 2003). The primary sources of potable water 

were treated surface water from the Bushy Park Reservoir and 

Edisto River (fig. 1). Although the CCPW currently (2004) has 

a treatment capacity that far exceeds normal demand, there is 

concern that demand may exceed delivery capacity in the event 

of damage to the water-distribution system. Hurricanes, 

earthquakes, and hard freezes potentially can result in such 

damage. Charleston is vulnerable to hurricanes and coastal 

flooding, as demonstrated in 1989 during Hurricane Hugo 

(Purvis, 1989). In 1886, the city was heavily damaged by the 

largest earthquake (magnitude 7.3) to strike the eastern United 

States in recorded history (Bollinger, 1977). Occasional hard 

freezes, such as one that occurred in December 1989, also can 

cause major disruptions in water-distribution service. One of 

the consequences of such disasters for the city of Charleston is 

the loss of potable water-transmission capacity, especially in 

the historic peninsula section of the city.

Approximately 2,400 kilometers (km) of water mains 

distribute treated surface water from the water-treatment plant 

in Hanahan, S.C. (fig. 1B) to retail and wholesale customers 

throughout CCPW’s water-service area. These water mains are 

constructed of cast iron, ductile iron, and a small portion 

consists of polyvinyl chloride (PVC) and high-density 

polyethylene (HDPE). Some of these water mains are located in 

the historic Charleston peninsula and consist of original cast 

iron installed in the early 1900's as well as newer ductile iron 

(J.B. Cook, Charleston Commissioners of Public Works, 

written commun., 2003). 

As part of the CCPW's overall asset-management 

program, water mains are replaced on a systematic basis using 

determining criteria such as breakage rate, location, and age. 

While most mains in the peninsula area are in structurally good 

condition, these are the oldest water mains in the distribution 

system, and the breakage rate is highest in the peninsula area. 

Therefore, it is reasonable to assume that in the event of 

extraordinary circumstances, such as hurricanes, hard freezes, 

and earthquakes, some of these older water mains will break. 

Water main breaks located between the treatment plant and 

downtown Charleston, or extensive water main breaks in the 

downtown area, can substantially reduce the water flow rates to 

the peninsula. This is known as a result of both historical 

experience and CCPW’s water system hydraulic modeling 

(J.B. Cook, Charleston Commissioners of Public Works, 

written commun., 2003).

In the event of an earthquake of similar magnitude (7.3) as 

the 1886 Charleston earthquake, it is estimated that 80 percent 

of the Charleston area homes would be without water for weeks 

to months because of damaged water pipes (South Carolina 

Emergency Preparedness Division, 2001). The loss of watertransmission capacity would not only eliminate potable water 

for domestic purposes, but also would limit fire-fighting 

capabilities in the areas affected by the ruptured mains. The 

South Carolina Emergency Preparedness Division (2001) 

predicts the possibility of more than 250 fires following a 

7.3-magnitude earthquake in the Charleston, S.C., area. 

The CCPW, in cooperation with the U.S. Geological 

Survey (USGS), evaluated the hydrologic and geochemical 

effects of an aquifer storage recovery (ASR) system on the 

Charleston peninsula from 1998 to 2002. Aquifer storage 

recovery is the concept of storing injected water in an aquifer 

for later recovery. The investigation evaluated the effects of 

injecting freshwater in a brackish aquifer, a process that can be 

cost effective in areas where surface-water reservoirs or areas 

for above-ground storage tanks are limited. A typical ASR 

system consists of at least one production well that is open or 

screened in the aquifer of interest. The production well is 

equipped with an injection line to transport water from land 

surface to the aquifer through the screens or open-hole portion 

of the well and a pump to transport the water from the aquifer 

back to land surface. Screened or open-hole observation wells 

are located near the production well to allow the monitoring of 

the spatial distribution of injected water and collection of 

ground-water samples. 

Purpose and Scope 

This report describes the hydrogeology and geochemistry 

of the Tertiary Santee Limestone/Black Mingo (SL/BM) 

confined aquifer (fig. 2), the northernmost equivalent of the 

Floridan aquifer system (Park, 1985), and the effect of ASR 
Introduction 3

Figure 1. Study area and location of the aquifer storage recovery pilot study site and phase-II site, Charleston, South Carolina.
4 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

Figure 2. Generalized stratigraphic and hydrogeologic column based on core collected from observation well 

CHN-800 in Charleston, South Carolina.

testing on aquifer hydraulic properties and recovered water 

quality. The report includes an evaluation of data collected to 

determine if ASR technology is a technically sound method for 

supplying downtown Charleston, S.C., with large quantities of 

potable water during emergencies.

The scope of this report includes discussion of results 

obtained from geophysical logging, aquifer testing, waterquality sampling, continuous monitoring of water-level and 

water-quality data, and numerical modeling during four ASR 

tests completed in Charleston, S.C. Results from geophysical 

logging and aquifer testing were used to enhance the knowledge 

of the hydrogeology of the SL/BM aquifer and to evaluate the 

transport of injected treated surface water in the aquifer. 

Continuous water-level and water-quality data collected from 

two observation wells during the ASR tests were used to 

evaluate the trends in injection/withdrawal rates, recovery 

efficiency, and long-term storage effects on the injected water 

quality. Finally, geochemical modeling was used to determine 

the dominant chemical reactions and hydraulic processes that 

affect the injected water quality during the ASR tests.

This investigation addressed issues that are part of the 

USGS mission. The results of this study are applicable to other 

ASR investigations in similar hydrogeologic environments and 

investigations of the Floridan aquifer system. The study 

advanced the knowledge of ASR in brackish-water aquifers and 

the hydrologic processes that occur in carbonate/sand aquifer 

systems. Recently developed numerical modeling techniques 

were used in this investigation to study solute transport and 

chemical reactions in the ground-water system. Results of this 

investigation can be used by local and State water managers to 

address issues of increased demand for water resources in 

coastal areas of increasing population. 

Previous Investigation

A pilot study was conducted during 1993–95 in which the 

USGS tested the feasibility of ASR technology in storing 

potable water at a pilot site (fig. 1) in Charleston, west of the 

Ashley River (Campbell and others, 1997; Mirecki and others, 

1998). During the pilot investigation, nine successive ASR 

cycles (each cycle consisting of injection, storage, and 

recovery) were conducted to evaluate hydrologic and waterquality changes resulting from injection of treated surface water 

into the SL/BM aquifer. 

Results of the pilot study indicated that ASR 

implementation in the SL/BM aquifer in the Charleston area is 

feasible, with recovery of potable water (recovery efficiency) 

ranging between 38 and 61 percent of the total volume injected 

(Campbell and others, 1997). Recovery efficiency is the 

percentage of stored water that meets a target water-quality 

criterion after retrieval from the aquifer (Pyne, 1995). During 
Hydrogeologic Framework 5

the pilot investigation, the period of storage typically was short, 

with durations ranging from 8 hours to less than 6 days, and the 

recovery of injected/stored water was discontinued prior to 

complete retrieval of all the injected water. The scope of the 

pilot investigation did not include investigating water-quality 

changes during long-term storage or completely characterizing 

the hydraulic properties of the SL/BM aquifer. Although the 

pilot ASR site was in Charleston, it was not located on the 

Charleston peninsula, which is the area that could be isolated 

from water supply during emergency situations. Lithologic 

comparison of core collected at the ASR pilot site (CHN-733) 

to core collected on the Charleston peninsula (CHN-800; fig. 1) 

indicated that the top of the SL/BM aquifer was about 7.3 m 

higher on the Charleston peninsula than at the ASR pilot site. 

Additionally, the aquifer portion of core collected from the pilot 

site consisted of more carbonate and less clastic material than 

the aquifer portion of core collected from the peninsula. 

Because further investigation was needed to address these 

issues, an ASR system (phase II) was installed in the downtown 

Charleston area (fig. 1). 

Description of Study Area

The phase-II ASR site, located immediately southwest of 

Colonial Lake in downtown Charleston, S.C. (fig. 1), was 

selected for this study because of access to potable water mains 

and the storm sewer, and also because it was possible to locate 

three new observation wells at selected distances and directions 

surrounding a newly installed production well. The production 

well was constructed to allow the injection of treated surface 

water from the city water mains. Recovered water was 

discharged to the storm sewer. 

Acknowledgments

The support received from John Cook and Randy 

Hoagland of the Charleston Commissioners of Public Works 

during all phases of this investigation has been invaluable. The 

Charleston Department of Parks and Recreation provided land 

for the study site. The interest and support from the Charleston 

Department of Parks and Recreation and from Fire Chief 

Russell Thomas are gratefully acknowledged. The analysis of 

numerous water-quality samples by Dixie Fanning and the 

Commissioners of Public Works laboratory is greatly 

appreciated. Keith Halford and Francis Riley of the U.S. 

Geological Survey assisted in aquifer-test planning and 

analysis. The interest and positive feedback from the residents 

of the neighborhoods surrounding Colonial Lake also are 

appreciated. 

Hydrogeologic Framework

The phase-II ASR site in the lower Atlantic Coastal Plain 

physiographic province is underlain by Quaternary, Tertiary, 

and Upper Cretaceous sediments that regionally have a total 

combined thickness of about 760 m (Campbell and others, 

1997). These depositional units are composed of terrigenous 

and carbonate sediments that unconformably overlie 

Precambrian and Paleozoic basalt (Gohn and others, 1977). The 

subject of the ASR study was the SL/BM aquifer within 

Tertiary Coastal Plain sediments. A generalized description of 

part of the Upper Cretaceous and all of the Tertiary and 

Quaternary stratigraphy and lithology at the ASR site (fig. 2) 

was based on a continuous core obtained during the drilling of 

observation well CHN-800 in Cannon Park in downtown 

Charleston (fig. 1). The Tertiary section beneath the ASR site 

was subdivided on the basis of lithology, paleontology, and 

geophysical logs (Bybell and others, 1998).

Tertiary Stratigraphy

The Black Mingo Group of Tertiary age is composed of 

two upper Paleocene formations — the Williamsburg Formation 

and the underlying Rhems Formation (Sloan, 1908; fig. 2). 

These sediments were deposited in inner shelf and marginalmarine depositional environments about 55 million years before 

present (Ma). The dominant lithology of the Black Mingo 

Group consists of interbedded sequences of greenish-gray 

mudstones and dark-gray to black laminated clays (Bybell and 

others, 1998). The total thickness of the Black Mingo Group in 

the area penetrated at the Cannon Park core site is 

approximately 117 m. The Rhems Formation is approximately 

75 m thick and lies between unconformable contacts at 227 and 

152 m below land surface (bls) in the Cannon Park core. The 

Rhems section consists of bioturbated, moderately calcareous 

silty clays, clayey silts, and muddy, very fine sands. The Lower 

Bridge Member of the Williamsburg Formation is 21 m thick 

and lies between unconformable contacts at 152 and 131 m bls. 

The Lower Bridge is a homogeneous section of bioturbated, 

moderately calcareous, clayey quartz silts and muddy, very fine 

quartz sands. The Chicora Member of the Williamsburg 

Formation is 21.3 m thick at the Cannon Park site and extends 

from 131 to 109 m bls. The Chicora Member consists of 

interbedded sequences of gray, bioturbated, muddy limestone; 

carbonate- and silica-cemented sandstones; moldic, quartzbearing pelecypod limestone; macrofossiliferous quartz sands; 

and white to pale-gray argillaceous sands and silts.

The middle Eocene Moultrie Member of the Santee 

Limestone unconformably overlies the Chicora Member of the 

Williamsburg Formation of the Black Mingo Group. The 

Moultrie Member, only 2.1 m thick at the Cannon Park site, is 

present from 109 to 107 m bls. The Moultrie Member consists 

primarily of a light-gray, quartz-rich, moldic, bryozoanpelecypod biosparrudite. The top of the Moultrie Member is 

extensively bioturbated with quartz-, phosphate-, and 
6 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

glauconite-filled burrows. The upper surface of the Moultrie 

Member is partially coated with a green phosphatic crust that 

marks the contact with the overlying late middle to upper 

Eocene Cross Member of the Santee Limestone. The Moultrie 

Member was deposited in a shallow, open marine-shelf 

environment about 45 Ma (Bybell and others, 1998).

The middle to upper Eocene Cross Member of the Santee 

Limestone is a white, dense, partially silicified calcilutite 

containing abundant foraminifers, echinoid spines, and 

ostracods (Fronabarger and others, 1995). The Cross Member is 

11.9 m thick and is present from 107 to 95.4 m bls at the Cannon 

Park site. The sediments were deposited in an outer continentalshelf environment about 41 Ma.

The Cross Member of the Santee Limestone is 

unconformably overlain by the Cooper Group, which consists 

of the upper Eocene Harleyville and Parkers Ferry Formations, 

and the upper Oligocene Ashley Formation (Ward and others, 

1979; Weems and Lemon, 1984). The Harleyville Formation is 

a compact, phosphatic, light-gray calcilutite containing 

abundant foraminifers (Bybell and others, 1998). The 

Harleyville Formation is 3.66 m thick and present between 

unconformable contacts at 95.4 and 91.7 m in the Cannon Park 

core. Both contacts are defined by extensively bioturbated 

phosphate- and glauconite-filled burrows. The overlying 

Parkers Ferry Formation is a dense, pale-yellow to light-gray 

calcilutite containing abundant echinoid spines and sand-size 

foraminifers. The Parkers Ferry Formation is 28.3 m thick and 

lies between 91.7 and 63.4 m bls in the Cannon Park core. The 

Harleyville and Parkers Ferry Formations were deposited in an 

outer-continental-shelf environment about 38 Ma. The upper 

Oligocene Ashley Formation of the Cooper Group 

unconformably overlies the Parkers Ferry Formation. The 

Ashley Formation is present from 63.4 to 22.6 m in the Cannon 

Park core. This 40.8 m thick section consists of a massive to 

bioturbated, pale-olive, fine-grained, quartz-rich, glauconite 

and phosphatic calcarenite containing abundant sand-size 

foraminifers (Fronabarger and others, 1995). The Ashley 

Formation was deposited in outer continental-shelf to marginal 

marine environments about 30 Ma. The Miocene Marks Head 

Formation is absent in the Cannon Park core.

Quaternary Stratigraphy

The upper Pleistocene Wando Formation unconformably 

overlies the upper Oligocene Ashley Formation. The Wando 

Formation, approximately 20 m thick at the Cannon Park site, is 

present from 22.6 to 2.74 m bls. The Wando Formation consists 

of quartz sand to shell-rich, clayey sand; organic-rich clays; and 

fine-grained, fossiliferous sand overlying a phosphate-pebble 

lag deposit (Fronabarger and others, 1995). The Wando 

Formation has a complex depositional history related to sealevel changes during the late Quaternary and is about 130,000 

years old (McCartan and others, 1980; Wehmiller and Belknap, 

1982). The sediment overlying the Wando Formation is 2.74 m 

thick and predominantly fill material.

X-ray Diffraction Analysis

Six sediment samples from the Cannon Park (CHN-800) 

core were analyzed to determine the dominant mineralogy in 

the SL/BM aquifer. Samples were analyzed at the USGS 

laboratory in Boulder, Colorado, using quantitative, whole 

rock, X-ray diffraction analysis methods described in Srodon 

and others (2001). The samples were collected from high and 

low permeable sections of the SL/BM aquifer at depths that 

ranged from 108 to 130 m bls. Four samples representing the 

high permeable zones of the aquifer were collected from 

sections of the aquifer referred to as the upper (UPZ) and lower 

(LPZ) production zones (fig. 3). Two UPZ samples were 

collected at depths of 109 and 112 m bls, and two LPZ samples 

were collected at depths of 126 and 129 m bls. Two samples 

were collected from less-permeable material between the UPZ 

and the LPZ at depths of 117 and 122 m bls. Results of the 

X-ray diffraction analysis are listed in table 1.

Calcite and quartz are the dominant minerals identified in 

the six sediment samples. Pyrite, an iron sulfide, is present in all 

the zones sampled but represents less than 3 percent by weight 

in all samples. Ankerite, a calcium carbonate and member of the 

dolomite group, contains iron, magnesium, and manganese 

(Ford, 1949). Ankerite is present only in sample CP-384 and 

represents 9 percent of the sample by weight (table 1). 

Clinoptilolite, a high silica zeolite, is an alterated by-product of 

volcanic ash (Heron, 1969). Clinoptilolite is present in the LPZ 

and less-permeable material and ranges from 2 to 13 percent by 

sample weight. Opal, a hydrated silica, is derived from both 

volcanic ash and from the decomposition of clinoptilolite under 

near-surface weathering conditions. Heron (1969) described 

several investigations that report the presence of zeolites 

and(or) opal in the lower Tertiary System in the southeastern 

States of Mississippi, Alabama, Georgia, South Carolina, North 

Carolina, and in core holes off the eastern coast of Florida. Opal 

is not present in the UPZ samples (CP-358 and CP-369) but 

represents between 0 and 23 percent (by weight) of the samples 

collected in the less permeable zone (CP-384 and CP-401) and 

LPZ (CP-412 and CP-423) (table 1). 

The clay minerals of the aquifer consist of ferruginous 

illite-smectite and aluminous illite-smectite. Smectite is a group 

of clay minerals with large surface areas and high cationexchange capacities (Pyne, 1995). Smectite-illite clay minerals 

form through the alteration of silicate minerals, such as 

feldspars, micas, and volcanic ash (Schlumberger Limited, 

2003). Clays are not present in the samples collected from the 

UPZ (CP-358 and CP-369) but are present in the LPZ and lower 

permeable material sampled and range from 9 to 12 percent by 

sample weight (table 1). 

Cation exchange capacity (CEC), expressed in 

milliequivalents per 100 grams (meq/100 g), is an indicator of 

the potential for ion exchange to occur in certain minerals and 

clays (Pyne, 1995). The estimated CEC of the sediment samples 

from the core are based on estimated CEC for clinoptilolite of 

180 and for illite-smectite of 100 meq/100 g. Estimated CEC 
Figure 3. Borehole geophysical logs for observation well CHN-811 at the aquifer storage recovery site, Charleston, South Carolina.
8 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

ranges from 12 to 36 meq/100 g (table 1) in the lower section of 

the aquifer (CP-384, CP-401, CP-412, and CP-423).

Hydrogeology

The South Carolina Coastal Plain strata can be divided into 

a series of aquifers and confining units based on their relative 

permeabilities. Aucott and Speiran (1985a) described five 

major Coastal Plain aquifers in the Charleston area. From 

youngest to oldest, these aquifers are the surficial, Floridan, 

Black Creek, Middendorf, and Cape Fear aquifers. The surficial 

aquifer is composed of Quaternary unconsolidated sands of the 

Wando Formation (fig. 2) and 2.74 m of overlying sediment/fill 

material. In Charleston, the Floridan aquifer system is 

composed of the Tertiary limestones and sands of the Moultrie 

Member of the Santee Limestone and the Williamsburg 

Formation of the Black Mingo Group, respectively, and is 

referred to as the SL/BM aquifer in Park (1985) and this report. 

The confined Black Creek, Middendorf, and Cape Fear aquifers 

are composed of unconsolidated sands within the respective 

Upper Cretaceous formations (Campbell and Gohn, 1994).

The focus of this study is the Tertiary limestone and sand 

aquifer of the Santee Limestone and the Black Mingo Group 

(fig. 2). Park (1985) and Meadows (1987) indicated that the two 

geologic units (the Santee Limestone and the upper 30.5 m of 

the Black Mingo Group) respond hydraulically as a single 

hydrogeologic unit. The combined units are characterized by a 

significant degree of hydraulic connection and little difference 

in potentiometric levels. The permeable zones of the Santee 

Limestone and Black Mingo Group are approximately 23 m 

thick at the ASR site. The SL/BM aquifer is confined above by 

the Cooper Group and the Cross Member of the Santee 

Limestone (fig. 2). Transmissivity of the SL/BM aquifer varies 

regionally from about 12 to 344 meters squared per day (m2/d; 

Park, 1985; Aucott and Newcome, 1986; Newcome, 1993). A 

storage coefficient of 1.0 x 10-4 was reported for this aquifer in 

Berkeley County (Newcome, 1993).

Predevelopment flow (prior to 1960) in the SL/BM aquifer 

was from northwest to southeast, generally perpendicular to the 

Table 1. Mineral abundances measured by quantitative X-ray diffraction microscopy and cation exchange 

capacity.

[UPZ, upper production zone; LP, less permeable zone; LPZ, lower production zone; CEC, cation exchange capacity; 

meq/100 g, milliequivalents per 100 grams]

Mineral

Sample identification (zone)

CP-358

(UPZ)

CP-369

(UPZ)

CP-384

(LP)

CP-401

(LP)

CP-412

(LPZ)

CP-423

(LPZ)

Weight percent

Non-clays

Quartz 16 49 37 56 24 19

Microcline feldspar 2 2 1 1 1 0

Plagioclase feldspar 2 1 0 1 1 0

Calcite 77 48 32 19 23 66

Ankerite 0 0 9 0 0 0

Pyrite 0 2 1 1 1 0

Opal 0 0 4 10 23 0

Clinoptilolite 0 0 7 7 13 2

Total non-claysa

a

Total weight percent may not equal 100 percent because of rounding.

97 102 91 95 86 87

Clays

Ferruginous illite plus smectite 0 09699

Aluminous illite plus smectite 0 00330

Total clays 0 0 9 9 12 9

Totala

 non-clays and clays 97 102 100 104 9 96

Estimated CECb (meq/100 g)

b

Based on estimated CEC for clinoptilolite of 180 and for illite plus smectite of 100 meq/100 g.

0 0 22 22 36 12
Hydrogeologic Methods 9

coastline (fig. 4). Predevelopment water-level altitudes in the 

SL/BM aquifer in the Charleston area were approximately 

7.6 m above NGVD 29. Ground-water recharge entered the 

aquifer at its outcrop area near Orangeburg and Lake Marion 

and flowed toward the southeast (fig. 4). Large-scale 

development of the aquifer began during the 1960's, especially 

in the area approximately 30 km northwest of Charleston. 

Water-level measurements collected in 1982 indicate a cone of 

depression in the SL/BM aquifer potentiometric surface (Aucott 

and Speiran, 1985b). By the early 1990's, extensive 

development combined with poor aquifer hydraulic 

characteristics resulted in large depressions in the 

potentiometric surface, and the lowest water-level altitudes 

(approximately -19.8 m NGVD 29) occurred in southern 

Berkeley County (Campbell and others, 1997). In 1998, the 

regional ground-water flow direction in the SL/BM aquifer was 

the reverse of the predevelopment flow direction in the 

Charleston area (fig. 5) and was toward the cones of depression 

(Hockensmith, 2001).

Hydrogeologic Methods

This investigation included installation of a production 

well and 3 observation wells, geophysical logging of wells, 

aquifer testing, monitoring long-term water levels and waterquality characteristics, and ASR testing. The methods used 

allowed characterization of the hydraulic properties of the 

SL/BM aquifer, evaluation of the movement of the injected 

water during ASR testing, and management of the ASR tests.

Well Construction and Instrumentation

A production well (CHN-812) and three observation wells 

(CHN-809, CHN-810, and CHN-811; fig. 1) were drilled at the 

phase-II ASR site using hydraulic rotary drilling techniques. 

The locations of the observation wells were selected to allow 

relatively rapid breakthrough of injected water at the two 

nearest observation wells (CHN-809 and CHN-810) during 

ASR testing, and to create a spatial distribution that optimizes 

the ability to characterize hydraulic properties, such as aquifer 

anisotropy and confining-unit leakage. All wells installed 

during this investigation were screened because of unsuccessful 

attempts at drilling, developing, and maintaining open-hole 

well construction. Prior to screening, unconsolidated sands in 

the SL/BM aquifer would collapse into the open hole and block 

part of the LPZ. Screen locations (table 2) were based on 

interpretation of natural gamma geophysical logs collected at 

well CHN-811 and lithologic core collected from well 

CHN-800 (fig. 1). After installation, the wells were developed 

by air injection and pumping until discharged water was free of 

drilling fluid and aquifer material.

The production well was constructed of 40.6-centimeter 

(cm) galvanized steel casing to 100 m bls and 16.8-cm 

galvanized steel casing from 100 to 134 m bls (table 2). The 

well also contained a 10.2-cm galvanized injection pipe and 

25-horsepower pump. Inline totalizing meters were installed on 

the injection and discharge pipes to measure the volume of 

water injected and recovered during each test. A 5.1-cm PVC 

pipe also was placed in the production well to facilitate waterlevel measurements.

Observation wells CHN-809 and CHN-810 were 

constructed of 10.2-cm PVC casing and screened at the same 

intervals as the production well (table 2). Observation wells 

CHN-811A and CHN-811B were 5.1-cm PVC wells installed in 

the same 15.2-cm borehole and screened in the SL/BM aquifer 

and overlying confining unit, respectively. Well CHN-811A 

was screened from 112 to 115 m and 130 to 134 m bls. Well 

CHN-811B was screened from 102 to 104 m bls. Screens of the 

two wells were separated by a bentonite seal located in the 

borehole between 108 and 109 m bls.

Wells CHN-809 and CHN-810 were equipped with 

pressure transducers, water-quality probes, and data loggers 

that recorded data at 15-minute intervals. Pressure transducers 

and data loggers were used to monitor water levels in the 

observation wells during all phases of testing. Water-quality 

probes and data loggers were used to monitor changes in pH, 

water temperature, specific conductance, and dissolved-oxygen 

concentrations in the observation wells at specific depths during 

ASR testing. Both wells contained two separate specificconductance probes located at depths that corresponded to the 

two most productive sections of the SL/BM aquifer. Initially, 

the specific-conductance probes were located at 116 and 131 m 

bls. On June 6, 2000, the 116-m and 131-m probes were moved 

to 112 and 129 m bls, respectively, because specificconductance profiles collected in the wells indicated that these 

depths were more permeable. Water-quality data were used to 

determine when to sample the observation wells during 

injection and also facilitated sample collection. The waterquality probes also were used to collect intermittent specificconductance profiles during ASR testing.

Geophysical Logging

Borehole geophysical logs were collected from all wells 

installed during this investigation and were used to help 

interpret site hydrogeology and select well-screen placement. 

Logs collected include natural gamma, spontaneous potential, 

single-point resistance, 40.6-cm short normal resistivity, 

163-cm long normal resistivity, lateral resistivity, formation 

resistivity, temperature, heat-pulse flow meter, and 

electromagnetic flow meter (EMFM). The natural gamma logs 

were collected prior to installing well casings and were used to 

determine the placement of well screens. Fluid resistivity, 

temperature, and flow-meter logs were used to determine the 

locations of the predominant ground-water flow zones in the 

screened portion of the SL/BM aquifer. 

Borehole geophysical logs collected from well CHN-811 

are the most complete set of logs collected at the ASR site 

(fig. 3). Low natural gamma counts on this geophysical log 
10 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

Figure 4. Approximate potentiometric surface of the Floridan (Santee Limestone/Black Mingo) aquifer system prior to development 

in South Carolina (modified from Aucott and Speiran, 1985a).
Hydrogeologic Methods 11

Figure 5. 1998 potentiometric surface of the Floridan (Santee Limestone/Black Mingo) aquifer system and 

Tertiary sand aquifer in South Carolina (modified from Hockensmith, 2001).
Table 2. Construction information for wells monitored during the aquifer storage recovery study in Charleston, South Carolina. [m, meters; cm, centimeters; SS, stainless steel; diam., diameter; PVC, polyvinyl chloride; @, at; N/A, not applicable] Well identification (fig. 1) Site identification Latitude Longitude Distance from production well CHN-812 (m) Casing type Borehole diameter (cm) Grouted interval (meters below land surface) Filter pack (meters below land surface) Screened o

interval (m

below l

surfac

CHN-812 324618080560900 32° 46′ 32.42′′ 79° 56′ 30.30′′ 0 16.8-cm 304 SS Riser 38.7 0 – 104 100 – 134 112 – 1

121 – 1127 – 1

CHN-809 324619080560900 32° 46′ 31.67′′ 79° 56′ 30.36′′ 23 10.2-cm SCH 80 PVC 14.9 0 – 32.6 109 – 134 112 – 1

121 – 1127 – 1

CHN-810 324620080561000 32° 46′ 33.52′′ 79° 56′ 30.91′′ 37 10.2-cm SCH 80 PVC 14.9 0 – 35.1 109 – 134 112 – 1

121 – 1127 – 1

CHN-811A 324632079562400 32° 46′ 32.73′′ 79° 56′ 24.60′′ 148 5.1-cm SCH 40 PVC 14.9 0 – 29.7 seal @ 109 m 109 – 134 112 – 1

130 – 1

CHN-811B 324632079562401 32° 46′ 32.73′′ 79° 56′ 24.60′′ 148 5.1-cm SCH 40 PVC 14.9 0 – 29.7 seal @ 101 m 101 – 108 102 – 1

CHN-800 324658079562500 32° 46′ 56.20′′ 79° 56′ 42.19′′ 795 Open hole 10.2 0 – 32.6 N/A 32.6 – 1

(Native matfilled in froto 168 m) 

CHN-733 324637079581400 32° 46′ 36.55′′ 79° 58′ 14.08′′ 2,704 Open hole 10.2 0 – 15.2 N/A 15.2 – 1

CHN-612 324541079580600 32° 45′ 38′′ 79° 58′ 06′′ 3,002 Open hole 15.2 0 – 40.2 N/A 40.2 – 1
Hydrogeologic Methods 13

Figure 6. Formation resistivity profiles collected in observation wells (A) CHN-809 and (B) CHN-810 during 

the injection phase of cycle 2 of the aquifer storage recovery study in Charleston, South Carolina.

represent coarse sand or limestone, as determined from 

lithologic data compiled from a core collected at well 

CHN-800. Well screens were placed in each borehole within 

the sand and limestone sections of the aquifer. 

Formation resistivity logs were collected in wells CHN809 and CHN-810 during the injection phase of ASR cycle 2 

(May 8 – June 16, 2000); logs were collected on May 19, June 1, 

and June 5 (fig. 6). Comparison of the logs indicates that two 
14 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

Figure 7. Electromagnetic flow-meter results while injecting freshwater into observation 

well CHN-809 during the aquifer storage recovery study in Charleston, South Carolina.

zones of high resistivity develop as low specific-conductanceinjected water flowed through the SL/BM aquifer. The top zone 

is centered on about 112 m bls and is approximately 2 m thick; 

this zone includes a portion of the aquifer that is not screened. 

The lower zone is centered on about 130 m bls. Because the 

sensor of the resistivity probe was near the top of the 

geophysical tool, the full section of the lower screen could not 

be logged. Therefore, the total thickness of the lower zone (as 

defined by the higher resistivity measurements) could not be 

determined. Results of the resistivity profiles depict a lower 

zone thickness of at least 4 m. 

Stationary borehole electromagnetic flow-meter data were 

collected to delineate changes in vertical flow rates in the 

screened sections of well CHN-809 (fig. 7), thereby providing 

a means for estimating the most productive portions of the 

SL/BM aquifer. Borehole EMFM results, measured in units of 

liters per second (L/s), represent the volume of water flowing 

through a hollow portion of the flow meter. The EMFM was 

equipped with a rubber skirt (diverter) that surrounded the 

EMFM and extended to the well casing. In the cased portion of 

the well bore, essentially all vertical flow at a given depth is 

directed through the flow meter. Within the screened portion of 

the well bore, however, vertical flow can occur through the 

gravel pack, resulting in an underestimation of flow at the given 

depth in the well bore.

Because ambient flow conditions in the SL/BM aquifer 

were similar to the quantifiable limits of the EMFM tool 

(0.006 L/s), the aquifer was stressed to induce flow within the 

well bore. Treated surface water was injected into the well bore 

at an average rate of 0.372 L/s. Borehole flow-meter flow rates 

were measured at various depths within and above the screened 

zones of the observation well. Measured flow rates were 

converted to percentages of average injection rate to delineate 

the areas of the screen where the vertical flow was lost to the 

aquifer. Dominant horizontal flow zones were assumed to be 

located where the greatest changes in the percentage of total 

flow occurred.

Borehole EMFM results indicate two major flow zones in 

the screened portion of well CHN-809 (fig. 7). An upper zone, 

located between 112 and 115 m bls, represented 49 percent of 

total flow into the well. A lower zone, located between 130 and 

134 m, represented 40 percent of the total flow. The remaining 
Hydrogeologic Methods 15

11 percent was received from the lower portion of the upper 

screen (about 9 percent), the middle screen (1 percent), and the 

upper portion of the lower screen (1 percent). These results 

indicate that the upper, middle, and lower screened sections 

represent total flow percentages of 58, 1, and 41, respectively. 

Determination of Aquifer Hydraulic Properties 

Two aquifer tests were conducted to determine the 

hydraulic characteristics of the SL/BM aquifer and whether 

these characteristics change as a result of ASR testing. The 

initial aquifer test was conducted in June 1999 prior to the 

injection of any surface water. The second aquifer test was 

conducted in November 2001 during the recovery phase of the 

final ASR test. 

The aquifer tests consisted of pumping production well 

CHN-812 at a constant discharge rate for several days while 

measuring water-level changes in wells CHN-612, CHN-733, 

CHN-800, CHN-809, CHN-810, CHN-811, and CHN-812 

(fig. 1). All of these wells are screened in or open to the SL/BM 

aquifer. Water-level changes in the production and observation 

wells were measured with pressure transducers and datalogging equipment. Barometric pressure was measured by 

using the data-logging equipment, and tidal stage data were 

collected at a USGS streamgage less than 1.6 km from the ASR 

site on the Cooper River (station number 021720711 [fig. 1]), 

which allowed correction of aquifer water-level data for 

barometric or tidal effects, as necessary. 

Because the SL/BM aquifer is potentially anisotropic 

and(or) affected by leakage from the adjacent confining units, 

the desired length of the pumping period was greater than 

1 week. The plan for the aquifer test was to pump the 

production well for as long as reasonable. In both tests, the 

pump shut off prior to the planned shutdown of the aquifer tests. 

The durations of the June 1999 and November 2001 aquifer 

tests were 9.3 and 7.3 days, respectively (table 3). Average 

discharge rates of 10 and 7.78 L/s were determined by using an 

inline totalizing flow meter for the June 1999 and November 

2001 aquifer tests, respectively (table 3).

The Moench (1985) method was selected to analyze the 

aquifer-test data because this method predicts water-level 

response to pumping a large-diameter well screened or open to 

a leaky confined aquifer. The method takes into account wellbore storage, skin effects, and the assumption that the confining 

unit is overlain or underlain by a constant-head boundary. The 

assumptions of the Moench (1985) method are reasonable for 

the Charleston ASR aquifer tests. Analytical results for the two 

aquifer tests are listed in table 3. Anisotropy was not required to 

match the water-level data measured during these two aquifer 

tests.

Analytical results using the Moench (1985) method were 

somewhat insensitive to the leakage factor. The leakage factor 

reported in table 3 is the maximum value allowed given the 

corresponding transmissivity and storage coefficient while 

maintaining the analytical method’s approximate sum of 

squares error (SSE; change in SSE less than 10 percent). A 

larger leakage factor increased the SSE for the given set of data. 

A lower leakage factor maintained the originally calculated 

SSE. Analytical results using the maximum leakage factor 

produced predicted time-drawdown curves that became flat by 

the end of the tested time interval. However, the measured water 

levels declined throughout the duration of the aquifer test. The 

contrast between the measured data and the time-drawdown 

curves indicates that the leakage factor was substantially less 

than the maximum value. The SSE calculated from analytical 

results that did not include leakage equaled the SSE calculated 

from the best-fit results, indicating that leakage into the SL/BM 

aquifer was minimal.

Results of the two aquifer tests indicate that aquifer 

properties did not change as a result of ASR cycling (table 3). 

Transmissivity values for the two tests are equal. Differences in 

the storage coefficient and the maximum leakage values are 

minimal and could be due to the insensitivity of the analytical 

Table 3. Estimated hydraulic characteristics of the Santee Limestone/Black Mingo aquifer based on 

the results of the June 1999 and November 2001 aquifer tests at the phase-II aquifer storage recovery 

site in Charleston, South Carolina.

[L/s, liters per second; m, meters; (L/s)/m, liters per second per meter; m2/d, meter squared per day; ---, not applicable]

Test dates June 28–July 7, 1999 November 8–15, 2001 Composite 

results

Average pumping rate (L/s) 10.0 7.78 ---

Maximum drawdown in 

CHN-812 (m)

79.9 84.7 ---

Specific capacity [(L/s)/m] at 

the given pumping rates 

0.12 0.092 ---

Transmissivity (m2/d) 37 37 37

Storage coefficient 

(dimensionless)

2 X 10-5 4 X 10-5 3 X 10-5

Maximum leakage factor 

(m-1)

3 X 10-4 7 X 10-4 7 X 10-4
16 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

method to the leakage factor. The consistent results of the two 

aquifer tests indicate that physical changes in the SL/BM 

aquifer as a result of calcite dissolution or other geochemical 

reactions have little effect on the hydraulic properties of the 

SL/BM aquifer during the time span tested.

Specific capacity, a measure of the well yield per unit of 

drawdown in the well, decreased over time during this 

investigation. Specific capacity depends on the well 

construction and hydraulic characteristics of the aquifer, 

decreases with increased discharge rate, and decreases with 

time during the pumping period (Heath, 1983). The maximum 

drawdown in the production well was greater during the 

November 2001 aquifer test (84.7 m) than during the June 1999 

aquifer test (79.9 m), even though the average pumping rate was 

lower for the November 2001 test (7.78 L/s) than for the June 

1999 test (10.0 L/s, table 3). Specific-capacity values for the 

June 1999 and November 2001 aquifer tests were 0.12 and 

0.092 (L/s)/m, respectively (table 3). 

Well plugging is defined as increased resistance to flow 

during artificial recharge (Pyne, 1995). Residual plugging, 

defined as plugging that remains during recovery, increases 

drawdown during recovery. The greater drawdown and 

coincident lower specific capacity for the November 2001 test 

compared with the June 1999 test indicate that plugging 

occurred at the site. Additional evidence of plugging was the 

decrease in injection rates for ASR cycles 2 through 4 (table 4), 

even though the same average injection pressure 

(145 kilopascals [kPa]) was maintained at the production well.

The introduction of foreign water to an aquifer may lead to 

many physical, biological, or chemical processes that degrade 

the quality of the injected water, the productivity of the aquifer, 

or the performance of the recharge well. The failure of an 

artificial recharge project in Arkansas identified several 

potential causes for reduction in recharge capability, including 

deposition of suspended material from water injected into the 

aquifer, air entrainment, rearrangement of aquifer materials, 

bacterial growth, biochemical or chemical precipitation, and 

swelling or dispersion of formation clays (Sniegocki, 1963). An 

artificial recharge investigation in Virginia identified clay 

dispersion as the major cause of hydraulic conductivity 

reduction during injection of freshwater into a brackish-water 

sand aquifer (Brown and Silvey, 1977). 

Table 4. Recovery efficiencies during the phase-II aquifer storage recovery study in Charleston, South Carolina.

[L, liters; L/s, liters per second]

ASR 

cycle Dates

Volume 

injecteda

(L)

a

Volume injected and injection rates were estimated for cycles 1 – 3 using water-level data collected at well CHN-809 and the Moench (1985) analytical 

method for aquifer tests.

Storage 

period 

(days)

Volume of 

potableb water 

recovered 

(L)

b

Potable water in this report was based on the secondary standard for chloride of 250 milligrams per liter (U.S. Environmental Protection Agency, 2000).

Total volume 

recovered 

(L)

Recovery 

efficiency 

(percent)

Injection

ratea

(L/s)

Withdrawal 

rate

(L/s)

1 10/26/99 – 04/10/00 7,190,000 30 2,462,975 31,672,422 34 0.82c

1.3

8.83

2 05/08/00 – 09/11/00 6,900,000 34 1,922,901 33,953,168 28 2.0 8.07

3 09/11/00 – 04/02/01 7,010,000 99 1,513,027 39,439,068 22 1.9 7.57

4 04/02/01 – 02/15/02 6,905,248 168 1,478,508 52,013,489 21 1.57 7.78

c

Injection rate varied for cycle 1.
Hydrogeologic Methods 17

Typically during the injection period of ASR cycles, 

production wells are periodically redeveloped by pumping to 

minimize the effects of plugging (Pyne, 1995). Redevelopment 

was not planned for this investigation but occurred 

inadvertently due to intermittent pump failures during the 

cycle-4 recovery phase (fig. 8). Specific-capacity values 

improved after each pump failure during this recovery phase, 

indicating that periodic redevelopment during the injection 

cycles should reduce the overall reduction in specific capacity 

during ASR implementation at the study site.

Aquifer Storage Recovery Testing

Four cycles of injection, storage, and recovery were 

conducted between October 1999 and February 2002 

(figs. 9 –12). Test dates, volumes of water injected and 

recovered, injection and withdrawal rates, and recovery 

efficiencies for each ASR cycle are listed in table 4. Each test 

consisted of injecting between 6.90 and 7.19 million liters (L) 

of water for storage periods of 1, 3, or 6 months. A similar 

length of storage was selected for cycles 1 and 2 to determine if 

ASR cycling had an effect on recovery efficiency, stored and 

recovered water quality, and overall cycle performance. Storage 

period lengths of increasing duration were chosen for the last 

two cycles to evaluate residence-time effects on the water 

quality of stored and recovered water. 

Total volumes of injected water determined from the inline 

totalizing flow meter during ASR cycles 1-3 were determined 

to be inaccurate. While the CCPW records contain no evidence 

that the meter was malfunctioning during the first three cycles, 

the volumes of injected water recorded for these cycles were 

significantly different from the volume recorded for ASR 

cycle 4. However, injection pressure measured at the 

production well and changes in water levels at the observation 

wells during the cycle-4 injection period were similar to the 

previous three tests. Because aquifer properties did not change 

during the ASR testing as determined from the two aquifer tests, 

the significant difference in total volume injected must have 

been a result of a malfunctioning flow meter. The meter was 

serviced during the storage period of ASR cycle 3 (December 

2000) to replace the dial face plate, which was scratched and 

unreadable. During ASR cycle 4, the injection rate was higher 

than that recorded for the three previous cycles. It is assumed, 

therefore, that the service in December 2000 repaired the meter. 

No problems were experienced with the inline totalizing flow 

meter that measured discharge.

The total volume of water injected during ASR cycles 1–3 

was estimated by using the Moench (1985) analytical method. 

Average injection rates for the cycles were estimated by using 

aquifer properties that accurately predicted the maximum 

measured drawdown at well CHN-809 for the November 2001 

aquifer test. Two injection-rate estimates were made for cycle 1 

because the average injection rate was adjusted during the 

cycle. The injection rates for cycles 1–3 were considered good 

estimates when the maximum predicted water-level change at 

well CHN-809 matched the maximum measured water-level 

change for the injection phases of the three ASR cycles. To 

confirm the appropriateness of this methodology, the Moench 

(1985) method was used to predict water-level changes during 

the injection phase of ASR cycle 4 by using the same aquifer 

property values used for cycles 1–3 and the measured injection 

rate for cycle 4. The Moench (1985) method predicted a 

maximum water-level change within 0.06 m of the measured 

water-level change of 3.16 m. This accuracy indicates that the 

methodology is appropriate for estimating the injection rates for 

the cycles when the flow meter was malfunctioning. In addition, 

numerical results of simulated water-level data for all four ASR 

cycles using the estimated injection rates compared well with 

measured data (discussed later in the Reactive-Transport 

Simulations section). The estimated injected volumes are listed 

in table 4.

Treated drinking water having an average specific 

conductance of 260 microsiemens per centimeter at 25 degrees 

Celsius (μS/cm) was injected into the production well at a 

constant rate (except cycle 1) until the specific-conductance 

value from the UPZ water-quality probe at well CHN-809 was 

less than 2,000 μS/cm for cycle 1 and 1,200 μS/cm for cycles 2–

 4. The injection rate was increased during cycle 1 to minimize 

the total time of injection. During cycles 2– 4, the injection rate 

was controlled by maintaining a injection pressure of 

approximately 138 kPa on the pressure gage located at the top 

of the casing of production well CHN-812. The 2,000-μS/cm 

value was chosen as an arbitrary threshold, primarily because 

this is the approximate value at which the average rate of 

change in specific conductance decreased significantly from an 

initially high rate (figs. 9 and 13). For cycles 2– 4, a threshold 

value of 1,200 μS/cm was used (figs. 10 –12). This specificconductance threshold value is less than a specific-conductance 

value of 1,467 μS/cm, which is approximately equivalent to the 

U.S. Environmental Protection Agency (USEPA) secondary 

standard (formerly known as the secondary maximum 

contaminant level) for chloride (250 milligrams per liter 

(mg/L), U.S. Environmental Protection Agency, 2000). 

Specific conductance and chloride are highly correlated at lowchloride concentrations (Hem, 1985). A linear regression of 

samples collected during this investigation indicates that a 

chloride concentration of 250 mg/L is equivalent to a specificconductance value of about 1,467 μS/cm with a correlation 

coefficient of 0.99. The injection phase ended several days after 

the specific-conductance value decreased below the threshold 

level at well CHN-809. 

The rates of change from initially high specificconductance values of about 7,200 μS/cm (representative of the 

aquifer) to lower specific-conductance values (representative of 

a mixture of aquifer and injected water) were lowest for cycle 1 

and approximately equal in the LPZ for ASR cycles 2– 4 

(fig. 13). The lower rate of change of specific conductance in 

the UPZ for most of the cycle-2 injection period was due to 

placement of the specific-conductance probe in a less 

permeable zone of the aquifer (116 m) than placement for 

cycles 3 and 4 (112 m). The specific-conductance probe was 
Figure 8. Water-level altitudes in wells during the cycle-4 recovery phase of the aquifer storage recovery study in Charleston, South Caro
Figure 9. Water-level altitude and specific conductance at observation well CHN-809 during cycle 1 of the aquifer storage recovery study in Charleston, South Carolina.
Figure 10. Water-level altitude and specific conductance at observation well CHN-809 during cycle 2 of the aquifer storage recovery study in Charleston, South Carolina. 2520151050 1,000

5/6/00

5/14/00

5/22/00

Date

5/30/00

6/7/00

6/15/00

6/23/00

7/1/00

7/9/00

7/17/00

7/25/00

8/2/00

8/10/00

8/18/00

8/26/00

9/3/00

9/11/00

9/19/00

0

2,0003,0004,0005,000

Specific conductance, in

microsiemens per centimeter

Water-level altitude, in meters

below NGVD 29

6,0007,0008,0009,000

Injection

Lower probe (131 meters)Upper probe (112 meters)Field sample (129 meters)Field sample (116 meters)Field sample (112 meters)

Pump off

Specific conductance probe

relocated to 129 meters

Specific conductance

probe relocated to

112 meters

Storage Recovery
Hydrogeologic Methods 21

Figure 11. (A) Water-level altitude, (B) specific conductance, (C) pH, and (D) water temperature at observation well CHN-809 during 

cycle 3 of the aquifer storage recovery study in Charleston, South Carolina.
Figure 12. Water-level altitude and specific conductance at observation well CHN-809 during cycle 4 of the aquifer storage recovery study in Charleston, South Carolina.
Hydrogeologic Methods 23

Figure 13. Changes in specific conductance at observation well CHN-809 during the injection phases of 

the aquifer storage recovery study in Charleston, South Carolina.
24 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

located at 112 m during cycles 3 and 4, and the rate of change 

of specific conductance was approximately equal in the UPZ 

during these cycles.

The length of the recovery phase was determined by the 

amount of time required to completely pump all of the injected 

water from the SL/BM aquifer. Recovery was stopped when the 

specific conductance of the water recovered from the 

production well equaled pre-injection values of about 

7,200 μS/cm (figs. 9 –12). Removal of all of the injected water 

was of utmost importance, so that differences in water-quality 

evolution (at the observation wells and production well) and 

recovery efficiency could be attributed to length of storage and 

not changing water-quality end members. For this reason and 

because of mixing that occurred during ASR testing, the volume 

of recovered water always significantly exceeded the volume of 

injected water (table 4). 

Specific-conductance profiles were collected in wells 

CHN-809 and CHN-810 periodically during cycles 3 and 4 to 

delineate the UPZ and LPZ (fig. 14). Profiles were collected 

during injection, storage, and recovery phases. Results from the 

specific-conductance profiles are less revealing than the fluid 

resistivity or EMFM logs; however, an upper productive zone is 

evident in both wells. Specific-conductance profiles collected 

during injection show the gradual displacement of brackish 

water in the SL/BM aquifer during the injection phase of 

cycle 4. The UPZ is a thin zone ranging in depth from 112 to 

115 m bls in well CHN-809 and from 112 to 114 m bls in well 

CHN-810. The LPZ is not apparent from the specificconductance profiles. 

Geochemical Methods and Processes

During this investigation, 193 water-quality samples were 

collected and analyzed for physical properties, major and minor 

ions, nutrients, and total trihalomethane concentrations. Waterquality analytical results coupled with inverse geochemical 

modeling aided in the evaluation of the dominant geochemical 

processes that occurred during the ASR tests in the SL/BM 

aquifer. Water-quality samples collected at the production well 

aided in estimating the recovery efficiency or volume of potable 

water that could be recovered during ASR implementation.

Water-Quality Sampling

Water-quality samples were collected directly from water 

spigots inline with the CCPW water mains and production-well 

discharge pipe and by using a portable piston-driven 

submersible pump. Five treated surface-water samples were 

collected to document injectant water quality. Thirty-two 

samples were collected from the production well during the 

recovery phase of the ASR cycles. A submersible pump was 

used to collect 151 samples from observation wells CHN-809 

and CHN-810. Three samples from observation well CHN811A and one sample from CHN-800 were collected to 

document water-quality differences among the observation 

wells.

Samples collected during this investigation were analyzed 

for physical properties, major and minor ions, and nutrients 

(Appendix 1). Physical properties included pH, water 

temperature, specific conductance, and dissolved-oxygen 

concentration, which were measured by using a water-quality 

field meter. Samples were shipped to the USGS water-quality 

laboratory in Ocala, Fla., and analyzed for major and minor 

ions, acid-neutralizing capacity (ANC), and nutrients by using 

standard USGS methods. In addition, 44 samples were 

collected for analysis of total trihalomethane concentrations 

from wells CHN-809 and CHN-810 during injection and 

storage, and from well CHN-812 during recovery of ASR 

cycle 4 (Appendix 2). One treated drinking-water sample was 

analyzed to determine the total trihalomethane concentration of 

the injected water. Water-quality samples were analyzed using 

USEPA method 502.2 (U.S. Environmental Protection Agency, 

1988) for total trihalomethane concentrations at the CCPW 

laboratory in Hanahan, S.C. The CCPW laboratory is certified 

by the South Carolina Department of Health and Environmental 

Control. 

Ground-water samples were collected from the production 

and observation wells using standard or modified USGS 

methods (Gibs and Wilde, 1998). Ground-water samples were 

collected from the observation wells by using a submersible 

pump and the low-flow purging technique to assure collection 

of aquifer water and not water stored within the well bore. The 

sampling method differed from the standard USGS method in 

that instead of installing sample tubing 24 hours prior to 

sampling, sample tubing was placed in the well the day of 

sampling (Barcelona and others, 1994; U.S. Environmental 

Protection Agency, 1995, 1996). Prior to sampling, the pressure 

transducer and one of the specific-conductance probes were 

removed from the well. The submersible pump was lowered to 

a depth adjacent to the screened section of the UPZ (112 or 

116 m bls). Pumping began after moving the down-hole waterquality meter as close to the pump as possible. Discharge from 

the submersible pump was monitored with a second waterquality meter and a flowthrough cell at land surface. The water 

level was monitored during the low-flow sampling process to 

ensure that the pumping rate was not causing drawdown in the 

sampled well. When water-quality properties (pH, temperature, 

specific conductance, and dissolved-oxygen concentration) at 

the pump discharge line stabilized and approximated those 

measured near the pump intake, the water sample was collected. 

After sample collection from the UPZ, the water-quality probe 

and submersible pump were lowered to the screened section 

adjacent to the LPZ (129 m bls), and a ground-water sample was 

collected using this same method. 

During the storage period of all ASR cycles, values of 

specific conductance in the observation wells increased 

considerably due to well-bore mixing. Because of this and to 

diminish the sampling time required, treated surface water was 

injected in the production well during storage. Injection at the 

production well forced the high specific-conductance well-bore 
Geochemical Methods and Processes 25

Figure 14. Specific-conductance profiles collected in observation wells (A) CHN-809 and (B) CHN-810 

during cycles 3 and 4 of the aquifer storage recovery study in Charleston, South Carolina.
26 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

water out of the screened zones within the observation wells, 

which allowed more rapid stabilization of physical properties 

during the low-flow sampling procedure. The specific 

conductance in samples collected during storage (figs. 11 and 

12) indicates that this sampling method allowed collection of 

ground-water samples representative of the productive zones of 

the SL/BM aquifer. The volume of water injected during 

storage was accounted for when calculating recovery efficiency 

as discussed below. 

Although brackish-water upconing was evident during the 

pilot ASR investigation, upconing was not evident during the 

phase-II ASR testing. Well-construction design accounted for 

the lack of upconing during the phase-II investigation. Wells 

installed during the pilot investigation (Campbell and others, 

1997) were of open-hole construction and were open to the 

SL/BM aquifer and upper and lower confining units; wells 

installed in the phase-II investigation were cased in the upper 

confining unit and screened solely within the SL/BM aquifer.

Recovery Efficiency 

Recovery efficiency is the percentage of stored water that 

meets a target water-quality criterion after retrieval from the 

aquifer (Pyne, 1995), and it is used as one measure to evaluate 

the results of an ASR investigation. The overall magnitude of 

this diagnostic property and changes in magnitude from one 

cycle to the next are important factors in determining whether 

ASR implementation is a worthwhile endeavor for the aquifer 

under investigation. Recovery efficiencies are controlled by 

hydrogeologic conditions, well and well-field design, and 

operational management (Merritt, 1985; Reese, 2002). 

Hydrogeologic conditions that can reduce recovery efficiency 

include severe mixing in aquifers that are thick, stratified, 

heterogeneous, or highly permeable; buoyancy stratification; 

migration of the freshwater bubble in aquifers with a high 

regional hydraulic gradient or in dipping aquifers; and 

migration of freshwater into semiconfining units in poorly 

confined aquifers (Merritt, 1985; Reese, 2002). Well design and 

management practices that can reduce recovery efficiency 

include using partially penetrating injection wells in aquifers in 

which buoyancy stratification may cause the freshwater bubble 

to rise above the screened or open portion of the well and well 

plugging, which can reduce recovery from the affected zones 

(Merritt, 1985; Reese, 2002). Improvements in recovery 

efficiencies that have been observed in field investigations and 

numerical simulations include (1) increasing the volume of 

water injected, (2) successive cycling after not fully recovering 

all of the previously injected water, and (3) centering adjacent 

injection wells around a central well when using multiple 

injection wells (Merritt, 1985; Reese, 2002). 

For this study, the USEPA secondary standard for chloride 

(250 mg/L; U.S. Environmental Protection Agency, 2000) was 

selected as the criterion for evaluating recovery efficiency. 

Chloride was selected because it behaves conservatively in the 

carbonate aquifer, and chloride concentrations in the treated 

surface water (19 – 60 mg/L) and ambient aquifer water 

(1,800 mg/L) differed significantly (Appendix 1). 

During the phase-II investigation, the total volume of 

recovered water greatly exceeded the total volume injected to 

assure that all injected water was removed from the aquifer 

prior to the start of a new ASR test (table 4). During the ASR 

pilot tests, recovery of injected/stored water was discontinued 

prior to complete retrieval of all of the injected water. As a 

result, the pilot investigation results indicated that recovery 

efficiency was between 38 and 61 percent of the total volume 

injected (Campbell and others, 1997). Because all of the 

injected water was not removed during each of the pilot 

recovery cycles, pilot recovery efficiencies were recalculated 

by adding the volume of water injected that remained in the 

aquifer at the end of one cycle to the total volume injected for 

the subsequent cycle. The volume of injected water remaining 

in the aquifer was estimated by using specific-conductance 

values representative of the injected water (174 μS/cm), native 

ground water (6,530 μS/cm), and recovered water samples 

collected immediately prior to the end of recovery (3,620 to 

5,110 μS/cm). This method assumes that specific conductance 

is a conservative tracer and that the relation between specific 

conductance and the percentage of injected water recovered is 

linear, a relation confirmed by the pilot ASR results (Campbell 

and others, 1997). A linear regression of specific conductance 

and chloride data from the pilot investigation resulted in a 

correlation coefficient of 0.99, indicating that specific 

conductance behaved conservatively in the pilot ASR 

investigation. Recalculated recovery efficiencies for the pilot 

ASR tests of 29 to 39 percent are more appropriate for 

comparison with the phase-II results. 

To calculate recovery efficiency, the volume of water 

injected during the storage period (to facilitate sampling the 

observation wells) was added to the total volume injected 

during the injection period. The total volumes injected were 

similar for all cycles. The estimated volume of treated surface 

water injected during the storage periods varied between 

276,305 and 442,845 L, which is between 4 and 6 percent of the 

total volume injected for the individual cycles.

Recovery efficiencies for the phase-II investigation varied 

between 21 and 34 percent for the four ASR tests (table 4). 

Recovery efficiencies were essentially equal for the 3-month 

(cycle 3) and 6-month (cycle 4) storage cycles. The recovery 

efficiencies are nearly equal even though injection and recovery 

rates differed for the two tests. Solute transport modeling, 

discussed below, is consistent with a fixed recovery efficiency 

of approximately 25 percent, regardless of the length of the 

injection period. 

Recovery efficiencies of 21 to 34 percent during this 

investigation compare well with the results of 12 ASR 

investigations of the Floridan aquifer system (Reese, 2002). 

Recovery efficiencies ranged from 2 to 47 percent during the 

first cycle of each of these Floridan aquifer system 

investigations. Of the 10 investigations that had multiple ASR 
Geochemical Methods and Processes 27

cycles, 7 showed an improvement in recovery efficiencies 

during the second cycle. The percent of injected water that was 

left in the aquifer after completion of the first cycle varied from 

23 to 92 percent for each of the Floridan aquifer system 

investigations (Reese, 2002). A common practice in ASR 

implementation is to limit recovery to allow some injected 

water to remain in the aquifer (Pyne, 1995; Reese, 2002). This 

procedure typically allows greater recovery efficiencies for 

subsequent cycles, as was the case in the pilot investigation 

(Campbell and others, 1997). During the phase-II investigation, 

essentially all injected water was removed from the aquifer 

prior to initiating the subsequent ASR cycle. The phase-II ASR 

investigation was designed to determine the amount of water 

that could be recovered following a single injection period, 

which is more consistent with the planned use of the stored 

water. 

Chemical Composition of Waters

In the ASR investigation, treated water with totaldissolved-solids (TDS) concentration of approximately 

100 mg/L was injected into the SL/BM aquifer containing 

brackish water with a TDS of approximately 4,000 mg/L. The 

dominant cation of the brackish aquifer water was sodium and 

the dominant anion was chloride (fig. 15A). The dominant 

cations in the treated water were calcium and sodium and the 

dominant anion was bicarbonate (fig. 15B). Upon injection into 

the aquifer, the composition of the injected water changed 

through mixing with the brackish water and reaction with the 

aquifer sediments. At the commencement of recovery during 

ASR cycle 3, water composition in the aquifer varied with 

distance from the injection and recovery well. Near the recovery 

well, as indicated by the initially recovered water from CHN812 (fig. 15D), the water composition was similar to the 

injected water, although sodium, calcium, chloride, and 

bicarbonate concentrations were slightly higher in the 

recovered water than in the injected water. At a distance of 23 m 

(well CHN-809, UPZ), the composition of the stored water 

(fig. 15C) was quite different from the injected water (fig. 15B). 

The stored water had a substantial concentration of sodium 

(15 millimoles per liter (mmol/L) or milliequivalents per liter 

(meq/L)) and chloride (8 mmol/L or meq/L, fig. 15C) relative to 

the injected water (fig. 15B), which indicates that part of the 

stored water mixed with the brackish aquifer water. In addition, 

calcium and magnesium concentrations in stored water at well 

CHN-809 were lower than in the injected water, and 

bicarbonate concentration was higher relative to chloride than 

in the brackish aquifer water.

As water continued to be pumped from the aquifer, the 

water composition changed to that of the brackish aquifer water. 

During this recovery process, sodium and sulfate 

concentrations behaved nearly conservatively relative to 

chloride. However, calcium and magnesium concentrations 

were slightly lower, and potassium and alkalinity 

concentrations were slightly higher than would be expected 

from conservative mixing of initial recovered water and final 

recovered water (fig. 16). The nonconservative behavior of the 

cations is indicative of cation-exchange processes that alter the 

cation composition of the water during ASR. 

Trihalomethanes

Trihalomethanes (THMs) are disinfection by-products that 

are formed when water containing naturally occurring dissolved 

organic carbon (DOC), such as water from the Edisto River and 

Bushy Creek Reservoir, is chlorinated for drinking-water 

purposes. Trihalomethanes are carcinogenic and, therefore, are 

regulated by the USEPA. The maximum contaminant level 

(MCL) for total THMs is 80 micrograms per liter (μg/L; U.S. 

Environmental Protection Agency, 2002). Total THMs consist 

of chloroform, bromoform, bromodichloromethane, and 

chlorodibromomethane.

Ground-water and treated surface-water samples were 

collected for THM analysis during ASR cycle 4 to determine 

the fate of THMs during ASR implementation in the SL/BM 

aquifer. Analytical results for samples collected during cycle 4 

are listed in Appendix 2. The highest concentrations of total 

THMs were measured in the treated drinking water prior to 

injection (57 μg/L). For this sample, the concentration of 

chloroform, bromodichloromethane, and chlorodibromomethane were 25, 20, and 12 μg/L, respectively. Bromoform 

was not detected (<1 μg/L) in this sample. The total THM 

concentration in the treated drinking-water sample was 

consistent with the range of total THM concentrations (46 to 

97 μg/L, with an annual average of 70 μg/L) reported in 

Charleston’s drinking-water supply for published sample 

results collected between January and December 2001 

(Charleston Commissioners of Public Works, 2003). 

Chloroform was the only constituent that contributed to the total 

THM concentration in ground-water samples. During recovery, 

total THM concentrations decreased from 8.5 to less than the 

detection limit (4 μg/L) at the production well. At these 

concentrations, THMs would not restrict the use of the 

recovered water for drinking-water purposes.

Analytical results collected from observation wells CHN809 and CHN-810 during the cycle-4 storage period indicate 

that while bromodichloromethane and chlorodibromomethane 

decreased to less than individual THM detection limits 

(<1 μg/L) during injection and storage, chloroform remained 

above detection limits during about 5.5 months of residence in 

the aquifer (fig. 17). During this storage period, chloroform 

concentrations at the two wells ranged from 3 to 28 μg/L 

(Appendix 2). While chloroform concentrations in well 

CHN-809 decreased over time, concentrations in well 

CHN-810 varied little or increased slightly. 

The highest chloroform concentration measured at well 

CHN-809 (28 μg/L) approximately equaled the treated 

drinking-water sample collected during this cycle (25 μg/L). 
Figure 15. Stiff diagrams depicting water quality in (A) native ground water, (B) injected water, (C) late storage from observation well CHN-809, and 

production well CHN-812 during cycle 3 of the aquifer storage recovery study in Charleston, South Carolina.
Geochemical Methods and Processes 29

Figure 16. Concentrations of selected ions relative to chloride concentrations during the cycle-3 recovery phase 

of the aquifer storage recovery study in Charleston, South Carolina.

0 10 20 30 40 50 0 10 20 30 40 50

Chloride, in millimoles per liter Chloride, in millimoles per liter

Magnesium, in millimoles per liter

Alkalinity, in millimoles per liter

Calcium, in millimoles per liter

Potassium, in millimoles per liter

0

0.4

0.8

1.2

0

0.4

0.8

1.2

Magnesium, measured

Magnesium, injected

Magnesium, aquifer

Magnesium, conservative mixing

0

0.4

0.8

1.2

0

5

10

15

Alkalinity, measured

Alkalinity, injected

Alkalinity, aquifer

Alkalinity, conservative mixing

Calcium, measured

Calcium, injected

Calcium, aquifer

Calcium, conservative mixing

Potassium, measured

Potassium, injected

Potassium, aquifer

Potassium, conservative mixing
30 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

Figure 17. Chloroform and chloride concentrations in samples collected from observation wells (A) CHN-809 

and (B) CHN-810 during cycle 4 of the aquifer storage recovery study in Charleston, South Carolina.
Geochemical Methods and Processes 31

Figure 18. Relative percentages of injected water in samples collected from observation wells CHN809 and CHN-810 during cycle 4 of the aquifer storage recovery study in Charleston, South Carolina.

The fact that this value was higher than the measured 

concentration in the treated drinking-water sample could be 

attributed to variability in the THM concentrations in treated 

drinking water over time. The sample containing 28 μg/L of 

chloroform was collected early in the storage cycle. The 

chloroform concentrations generally stabilized in well CHN809 during mid to late storage with concentrations of 14 to 

20 μg/L in the UPZ and 13 to 16 μg/L in the LPZ (fig. 17A, 

Appendix 2). Chloride concentrations measured in samples 

collected from well CHN-809 during storage were relatively 

consistent (fig. 17A; Appendix 2). 

The relative percentages of injected water in ground-water 

samples collected at the observation wells were calculated and 

plotted (fig. 18) to determine if chloroform behaved 

conservatively (like chloride) during ASR implementation. 

Comparison of the relative percentages of injected water 

based on chloroform and chloride concentrations (fig. 18; 

Appendix 2) indicated that the majority of the estimates based 

on chloroform concentrations were lower than the estimates 

based on chloride. Therefore, mixing of injected and aquifer 

water cannot solely explain the reduction in chloroform 

concentrations. At least three chloroform samples collected 

during this investigation represented a higher concentration 

than could be explained by mixing. Although the reason for this 

disparity is unknown, it could be attributed to the variability of 

chloroform concentrations in the injected water over time.

Relative percentages of injected water in ground-water 

samples based on chloroform concentrations compared to 

chloride concentrations (fig. 18) and the absence of bromoform, 

bromodichloromethane, and chlorodibromomethane in any 

ground-water samples indicated that the majority of all THM 

samples collected during ASR cycle 4 were nonconservative. 

The mechanism of THM reduction was not evaluated during 

this investigation; however, previous investigations (Pyne, 

1995; Thomas and others, 2000) indicate that mixing and 

microbial biodegradation may decrease THM concentration 

during storage and recovery. 
32 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

Chemical Reactions During Aquifer Storage 

Recovery

The observed changes in water composition in the stored 

and recovered waters can be explained by chemical reactions 

between the injected surface water and the ground water and 

aquifer sediments. The predominant reactions in Coastal Plain 

aquifers are carbonate-mineral and cation-exchange reactions 

(Chapelle and Knobel, 1985). Both dolomite and calcite are 

carbonate minerals that occur in Coastal Plain sediments, but of 

the two, only calcite was identified by quantitative X-ray 

diffraction (table 1) in sediment samples. Cation exchange is 

indicated by the variations in calcium and sodium 

concentrations measured in the stored and recovered waters 

(fig. 15). Thus, calcite dissolution and precipitation and cation 

exchange are likely reactions in the SL/BM aquifer. 

In addition, it is possible to have redox reactions involving 

dissolved oxygen, organic matter, iron, and sulfur. If organic 

matter is present in the aquifer, sulfate reduction is a possible 

reaction. However, the concentration of sulfate was nearly 

conservative with respect to chloride throughout the 

investigation, and sulfide concentrations were low in the 59 

samples that were analyzed. It is concluded that during the 

investigation, sulfate reduction was minimal. 

The injection of oxygenated water could lead to oxidation 

of pyrite, organic carbon, and other reduced 

substances. The maximum amount of 

dissolved oxygen in the injected water was 

approximately 0.25 mmol/L (8 mg/L), 

which can be expected from equilibration of 

surface water with the atmosphere. This 

amount of dissolved oxygen is sufficient to 

generate only about 0.125 mmol/L of sulfate 

(12.5 mg/L), which is negligible. By the 

same reasoning, oxidation of reduced iron 

(ferrous iron) is unlikely to have a large 

effect on water composition; however, iron 

oxidation may still be an important reaction 

in ASR. Oxidation of ferrous iron is 

mediated by bacteria, and bacterial colonies 

and the formation of ferric oxyhydroxide 

precipitates can lead to well clogging. 

Because of the small effect on water 

composition, no chemical data are available 

that are adequate to evaluate whether iron 

oxidation contributes to the observed 

decrease in specific capacity over the course 

of the ASR experiments. 

Other reactions with gypsum and 

aluminosilicates are thought to be unlikely 

or relatively unimportant. Gypsum is 

undersaturated in the brackish water 

(saturation index (SI) < -2) and should not 

precipitate under injection conditions. 

Gypsum was not identified by X-ray 

diffraction analysis and was assumed not to 

be present within the aquifer. Although aluminosilicate 

minerals are present in the aquifer, it was assumed that reactions 

with these minerals were too slow to substantially affect the 

chemistry or aquifer properties during the four ASR cycles. 

The partial pressure of carbon dioxide (CO2, table 5), as 

calculated from pH and alkalinity by geochemical speciation 

modeling, is approximately atmospheric (log partial 

pressure = -3.5) for the injected water and the initial recovered 

water; however, the partial pressure of carbon dioxide was 

considerably less than atmospheric in the water at well 

CHN-809. The low partial pressure at CHN-809 is consistent 

with dissolution of calcite, which consumes dissolved CO2. 

Saturation indices for calcite (table 5) indicate that the brackish 

water in the aquifer is at equilibrium with calcite (SI = 0.02). 

The injected water is undersaturated with respect to calcite 

(SI = -0.74), which indicates that calcite may dissolve as the 

water is injected into the aquifer. The water at CHN-809 at the 

start of recovery was supersaturated with respect to calcite 

(SI = 0.76). This supersaturation may have been caused by 

mixing of waters within the well bore during sampling. At highpH and low-calcium concentrations, large supersaturations can 

be caused by mixing waters with differing concentrations of 

CO2 or calcium. 

Inverse geochemical modeling with PHREEQC (Parkhurst 

and Appelo, 1999) was used to account for the difference in 

Table 5. Chemical composition of four water samples collected during cycle 3 

of the aquifer storage recovery study in Charleston, South Carolina.

[°C, degrees Celsius; su, standard units; mg/L, milligrams per liter; CaCO3, calcium carbonate; 

CO2, carbon dioxide; <, less than]

Constituent

Brackish 

background 

aquifer water 

(CHN-812)

Injected 

surface 

water

Initial 

recovered 

water 

(CHN-812)

Start 

of 

recovery 

(CHN-809)

Sample date 3/1/01 11/2/00 1/31/01 12/18/00

Temperature, °C 25.0 a25.4

a

Average value for two samples collected on 4/11/01 and 5/23/01.

b21.9

b

Temperature value measured on 2/1/01.

17.5

pHc

, su

c

Samples collected on 3/1/01 and 12/18/00 are field values; samples collected on 11/2/00 and 

1/31/01 are laboratory values.

7.6 7.8 7.9 10.3

Calcium, mg/L 23 20 33 2.6

Magnesium, mg/L 25 2.3 3.2 3.5

Potassium, mg/L 39 2.4 4.5 12

Sodium, mg/L 1,500 18 35 330

Alkalinityd, mg/L as CaCO3

d

Alkalinity is assumed to be the acid-neutralizing capacity of the unfiltered water sample.

715 32 47 291

Chloride, mg/L 1,700 23 40 280

Silica, mg/L 41 7.6 10 19

Sulfate, mg/L 260 33 40 75

Calcite saturation index .02 -.74 -.67 0.76

Log partial pressure CO2 -1.70 -3.23 -3.26 -5.42

Dissolved oxygen, mg/L < 2.0 a7.0 e< 2.5

e

Dissolved-oxygen concentration measured in sample collected on 2/1/01.

<1.5
Reactive-Transport Simulations 33

composition between injected and stored waters as represented 

by the initial recovered water from well CHN-812 and the stored 

water at observation well CHN-809 just prior to recovery 

(table 5). The initial recovered water from well CHN-812 had a 

charge imbalance of about 10 percent between analyzed cations 

and anions. The charge imbalance, a measure of analytical 

errors, would be zero if all cations and anions were analyzed 

exactly. If all of the error in the analysis of recovered water from 

CHN-812 could be attributed to the calcium concentration, the 

water composition could be produced, with minimal amounts of 

cation exchange, by mixing 99 percent injected water and 

1 percent brackish water. If the charge-balance error cannot be 

attributed to calcium, additional minor amounts of calcite and 

CO2 reaction would be needed to account for the water 

composition of the recovered water.

Inverse geochemical modeling indicated that mixing, 

cation exchange, and calcite dissolution were sufficient to 

account for the evolution in chemical composition from injected 

water to stored water at well CHN-809 (table 6). The stored 

water at well CHN-809 can be explained as a mixture of 

87 percent injected water and 13 percent brackish aquifer water. 

In addition, approximately 1.5 mmol/L of calcite was dissolved, 

and calcium and magnesium were exchanged onto the clays in 

the aquifer as potassium and sodium were released.

Parkhurst and Kipp, 2002) was used to simulate flow, transport, 

and chemical reactions in the aquifer. The development of the 

reactive-transport model requires calibration of flow-model 

parameters that simulate the water-level altitudes measured 

during aquifer testing. In addition, other model parameters must 

be adjusted to adequately simulate the measured breakthrough 

of conservative chemical constituents at the observation and 

recovery wells during the ASR cycles. Finally, the chemical 

reactions and initial conditions in the aquifer must be specified, 

including the amounts of mineral and exchange sites in the 

aquifer sediments.

The PHAST simulator does not account for the density 

effects that can occur by injecting freshwater into an aquifer 

containing brackish water. Density effects were ignored because 

the aquifer layers are thin, only 4 m thick, and because the 

salinity of the brackish water (4,000 mg/L) was less than the 

5,000-mg/L suggested threshold for buoyancy stratification 

(Pyne, 1995; Reese, 2002).

Flow-Model Parameters

PHAST implements a finite-difference flow model that 

uses a point distributed grid, such that nodes define the edges of 

the simulation region. Cell faces are located halfway between 

nodes in each direction; for cells that border the exterior of the 

simulation region, cell faces coincide with the nodes. Values of 

head are calculated for each node in the simulation region for 

each time step. Aquifer properties (porosity, hydraulic 

conductivity, and dispersivity among others) are defined by 

element, which is the volume defined by eight nodes.

Electromagnetic flow logs collected during injection at 

well CHN-809 delineated two dominant productive zones in the 

screened sections of the well that were each less than 4 m thick 

(fig. 7). Formation resistivity logs collected at wells CHN-809 

and CHN-810 during ASR cycle 2 injection also showed two 

productive zones that were about 4 m thick or less containing 

water with low specific-conductance (fig. 6). Initial flow 

simulations for parameter estimation included two 2-m-thick 

productive zones, the centers of which were located at 113.5 and 

131.5 m bls. Confining units were assigned above the UPZ, 

between the UPZ and LPZ (16 m thick), and below the LPZ. The 

confining zones were discretized with fine node spacing (0.25 

m) near the productive zones and coarsening node spacing with 

distance vertically from the productive zones (fig. 19). The 

productive zones were represented vertically with three nodes. 

Hydraulic conductivity was initially assigned to produce a 

transmissivity of 37 m2

/d (table 3), with the transmissivity of the 

UPZ about 50 percent greater than that of the LPZ, which is 

consistent with the transmissivity estimate using the analytical 

methods discussed earlier and the relative flows observed in the 

electromagnetic flow logs. In addition, the UPZ and LPZ were 

divided into two contrasting hydraulic conductivity layers to 

provide a better simulation of solute transport. The initial 

hydraulic conductivity estimates were as follows: low hydraulic 

conductivity layer of LPZ, 1 meter per day (m/d); high hydraulic 

Table 6. Mixing fraction and mole transfers that account for the 

water composition at observation well CHN-809 at the start of the 

cycle-3 recovery phase during the aquifer storage recovery study 

in Charleston, South Carolina.

[mmol/L, millimole per liter]

Solution or reactant Mixing percentage or 

mole transfer

Injected surface water, percent 87

Brackish aquifer water, percent 13

Calcite, mmol/L 1.5

Calcium exchange, mmol/La

a

For cation-exchange reactions, positive-mole transfer increases and 

negative-mole transfer decreases the cation concentration in solution.

-1.9

Potassium, exchange, mmol/La .12

Magnesium exchange, mmol/La -.07

Sodium exchange, mmol/La 3.9

Reactive-Transport Simulations

A small number of chemical reactions appear to account for 

the major changes in water composition during injection and 

storage—mixing with brackish aquifer water, calcite dissolution 

and precipitation, and cation exchange. By assuming that all of 

the chemical reactions are equilibrium processes, a simple 

reactive-transport model can be developed to simulate the ASR 

cycles. The simulator PHAST (Parkhurst and others, 1995; 
34 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

Figure 19. Grid used for simulations by which flow-model parameters were estimated from aquifer-test data at the aquifer storage 

recovery site in Charleston, South Carolina.
Reactive-Transport Simulations 35

conductivity layer of LPZ, 5 m/d; low hydraulic conductivity 

layer of UPZ, 2.5 m/d; and high hydraulic conductivity layer of 

UPZ, 10 m/d. Each layer is 2 m thick, which results in 

transmissivity of 37 m2/d. Because the transmissivity is well 

constrained by the previous analytical estimation methods, only 

the hydraulic conductivity of the upper layer of the UPZ (the 

high hydraulic conductivity layer) was adjusted by parameter 

estimation to allow less variation in the transmissivity of the 

combined layers.

The flow system was assumed to be radially symmetric. 

Simulations were restricted to a single quadrant, the other 

quadrants being equivalent by symmetry. Pumping and 

injection rates were decreased to one quarter of the measured or 

estimated values for the ASR cycles. The restricted simulation 

region allowed finer grid discretization and faster simulations. 

The simulation region (fig. 19) was discretized in the X and Y 

directions with variable but increasing spacing of nodes, 

ranging from 2.5 m near the pumping well to a maximum of 

2,000 m at the margins of the simulation region. The simulation 

region extended from 0 to 5,000 m in the X and Y directions. 

The bounding planes at X = 0 m and Y = 0 m were no-flow 

boundaries because of symmetry; the bounding planes at X = 

5,000 m and Y = 5,000 m were assigned leaky boundary 

conditions. Initial heads for all nodes and the specified heads of 

the leaky boundary conditions were assigned an arbitrary, 

uniform value. 

Drawdown data for wells CHN-809, CHN-810, CHN811A, and CHN-800 from the June 1999 and November 2001 

aquifer tests were used to fit three flow-model parameters — the 

hydraulic conductivity of the upper half of the UPZ, the vertical 

hydraulic conductivity of the confining units, and the specific 

storage of all layers. Drawdown data were selected for each 

well at 200; 1,000; 3,000; and 13,360 minutes as representative 

of the time sequence of drawdown during the 1999 aquifer test. 

For the 2001 aquifer test, drawdown data were selected for each 

well at 215; 1,000; 3,000; and 10,500 minutes. The parameter 

estimation code UCODE (Poeter and Hill, 1999) was used to 

adjust the flow-model parameters to produce a least-squares fit 

to the selected drawdown data. A standard deviation of 0.2 m or 

0.1 m (last point in the time sequence for each well in each 

aquifer test) was used to weight the observations for fitting. 

Because the fits were least sensitive to the vertical hydraulic 

conductivity of the confining units, this parameter was held 

constant at a series of values and the other two parameters were 

fit. Parameters were fit for each aquifer test separately (table 7).

The variation in the fit parameters was small over the 

entire range of vertical hydraulic conductivity of the confining 

units. The specific storage ranged from 0.9 x 10-5 to 1.5 x 10-5

per meter (m-1) and the hydraulic conductivity of the upper half 

of the UPZ ranged from 6.9 to 9.1 m/d in both aquifer tests 

(table 7). A vertical hydraulic conductivity for the confining 

units of 1 x 10-6 m/d produced the minimum weighted sum of 

residuals squared (R2

) for the 2001 aquifer test, whereas a value 

of 0.0 m/d marginally produced the smallest R2

 for the 1999 

aquifer test. The low values of vertical hydraulic conductivity 

for the confining units indicate that leakage has a relatively 

small effect on the head distribution during the aquifer tests, 

which is consistent with the analytical results. A value of 

0.0 m/d, which implies no leakage, was selected for use in the 

reactive-transport simulations. Although leakage certainly 

occurs in most aquifer systems, ignoring leakage makes very 

little difference in the goodness of fit to the aquifer test 

observations or in the reactive-transport simulations. By 

ignoring leakage, however, it is not necessary to discretize the 

confining units, which decreases the number of nodes and 

allows simulations to run faster.

By assuming zero leakage (Kz, confining = 0.0 m/d), the 

other parameters for the reactive-transport simulations were 

selected from the results shown in table 7. The specific storage 

was 1.5 x 10-5 m-1, which is consistent with the parameter 

estimation of both aquifer tests, and the hydraulic conductivity 

of the upper half of the UPZ was selected to be 8.4 m/d, which 

is the mean of the estimates from the two aquifer tests (table 7). 

The vertical hydraulic conductivities of the layers of the 

productive zones were assumed to be one-tenth of the 

horizontal hydraulic conductivities. 

The measured drawdown data and the drawdown 

simulated by using the selected parameters are shown in 

figure 20 for the 1999 and 2001 aquifer tests. Oscillations in the 

measured water levels are due to tidal-loading effects (fig. 20). 

Table 7. Flow-model parameters fit from the June 1999 and November 2001 aquifer-test data collected at the phase-II 

aquifer storage recovery site in Charleston, South Carolina.

[Kz, confining, vertical hydraulic conductivity of the confining units; m/d, meter per day; Ss, specific storage; m-1, maximum leakage factor; 

Khigh, UPZ, horizontal hydraulic conductivity in the upper half of the upper productive zone; R2

, weighted sum of squares of residuals]

2001 aquifer test 1999 aquifer test

Kz, confining

(m/d)

Ss

(m-1)

Khigh, UPZ

(m/d) R2 Ss

(m-1)

Khigh, UPZ

(m/d) R2

1.0x10-5 0.9x10-5 6.9 109 0.9x10-5 8.2 680

1.0x10-6 1.2x10-5 7.4 64 1.3x10-5 8.9 490

1.0x10-7 1.4x10-5 7.6 74 1.4x10-5 9.1 459

0 1.5x10-5 7.6 80 1.5x10-5 9.1 455
Figure 20. Measured drawdown data for November 2001 and June 1999 aquifer tests and simulated drawdowns using the best-fit paramet

November 2001 aquifer test at the aquifer storage recovery site in Charleston, South Carolina.
Reactive-Transport Simulations 37

Figure 21. Measured water-level altitude in observation well CHN-809 and simulated water-level altitude 

calculated by using the selected flow-model parameters for the period of investigation at the aquifer storage 

recovery site in Charleston, South Carolina.

The simulated drawdown for the 2001 test differs by less than 

1 m for all observations. Results of the 1999 aquifer test are 

similar except for well CHN-809, which has a difference of 

more than 1 m between measured and simulated drawdown. 

The same parameters could not fit simultaneously the 

drawdown of wells CHN-809 and CHN-810 in the 2001 aquifer 

test, which were very similar at early times in the test even 

though the distances to the wells from the pumping well were 

different (23 m and 37 m, respectively). 

Halford and Campbell (2004) reported the potential of 

large regional anisotropy for the aquifer. However, the fit to the 

two more distant wells (CHN-811A and CHN-800) and the 

good correspondence of simulated and measured drawdown at 

wells CHN-733 and CHN-612 (data not shown), which were 

not included in the fitting process, are not consistent with a large 

regional anisotropy. These four wells are located in different 

directions and as much as 3,000 m distant from the pumping 

well, conditions that should demonstrate regional anisotropy. In 

addition, anisotropy cannot explain the inconsistent pattern of 

drawdown at wells CHN-809 and CHN-810 during the two 

aquifer tests. The goodness of fit between simulated and 

measured drawdown for all of the wells justifies the use of 

horizontal isotropy in all subsequent simulations described in 

this report. 

The water level at well CHN-809 was simulated for the 

entire period of investigation by using the selected flow-model 

parameters and the measured and estimated injection and 

pumping rates. The good match with observations over the 

entire period of investigation (fig. 21) gives credence to the 

adequacy of the flow simulations and to the injection rates that 

had to be estimated. Similar correspondence between measured 

and simulated water-level altitudes was observed for well 

CHN-810 (not shown).
38 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

Figure 22. Measured chloride concentrations at observation well CHN-809 

during injection, storage, and recovery in cycle 3 of the aquifer storage recovery study in Charleston, South Carolina.

Transport Simulations

The grid for reactive-transport simulations was modified 

from the grid used in estimating the flow-model parameters by 

limiting the extent to 3,000 m and removing some of the nodes 

in the range of 200 to 400 m in the X and Y directions. The 

smaller number of nodes was chosen to speed up the overall 

simulation time, while preserving the fine grid in the vicinity of 

the production and observation wells. Discretization in the Z 

direction, boundary conditions, and flow-related parameters 

were unchanged. 

Although the drawdown at multiple wells is adequately 

described by simulations using the selected values of hydraulic 

conductivity and storage, breakthrough of chemical constituents 

at observation wells places even greater constraints on flow and 

transport model parameters, particularly on the thickness and 

porosity of the productive zones and the dispersivity of the 

system. Chloride is a conservative constituent, and the large 

contrast between the brackish aquifer water and the injected 

freshwater provides a good tracer of the movement of injected 

water into the aquifer.

The chloride concentrations at observation well CHN-809 

during ASR cycle 3 are shown in figure 22. Given the relatively 

low injection rate, 0.11 cubic meter per minute (m3/min), which 

is equivalent to 30 gallons per minute (gal/min), the rapid 

breakthrough of water with low chloride concentrations at the 

observation well (23 m from the injection well) indicates that 

the injected water apparently flows through a small volume of 

aquifer. The effective volume through which water flows 

between the injection well and the observation well can be 

estimated from the cumulative volume of water injected up to 

the time when chloride concentration at the observation well 

was approximately half of the concentration in the brackish 

aquifer water (850 mg/L). For ASR cycle 3, the breakthrough of 

this concentration occurred approximately 8 days after the start 

of the injection. The cumulative volume of water injected after 

8 days was approximately 1,300 cubic meters (m3

). The volume 

of the aquifer filled by this volume of injected water was 

calculated by using the following equation:

(1)

where 

is the volume of injected water, in cubic meters;

is the porosity of the aquifer, unitless;

is the thickness of the aquifer, in meters; 

is approximately 3.14; and 

is the distance from the injection well to the observation well, 23 m. 

Solving for the product of depth times porosity gives = 

0.8 m. Thus, for reasonable values of porosity, 0.4 to 0.1, the 

thickness of the aquifer must be approximately 2 to 8 m, which 

is consistent with the relatively thin zones for which significant 

flow and low specific conductance were indicated in the well 

logs.

During storage, the minimum concentration of chloride 

observed at well CHN-809 was approximately 200 mg/L 

(fig. 22), which differed from the injection concentration of 

approximately 40 mg/L. Thus, although a large proportion of the 

water at the observation well during storage in ASR cycle 3 was 

injected water, a substantial proportion (approximately 

10 percent) was brackish aquifer water. 

The parameter in the reactive-transport simulations that 

controls the amount of mixing between injected water and 

brackish aquifer water is the dispersivity. Initial transport 

calculations included two 2-m productive zones with flowmodel parameters from the analytical methods for aquifer tests. 

The porosity and dispersivity were adjusted to match the 

chloride concentrations at observation wells CHN-809 and 

CHN-810. A dispersivity of about 15 m and porosity of 0.2

resulted in an adequate fit for ASR cycle 3 for the 

observation wells. However, the simulated chloride 

concentration for the recovery well (CHN-812) during 

storage was about 120 mg/L, which is three times 

greater than the measured chloride concentration in the 

initial recovered water. Thus, simulations with a 15-m 

dispersivity failed to reproduce the relatively low 

chloride concentrations near the pumping well, which 

is a critical failure with respect to the simulation of 

recoverable potable water.

A dispersivity of 15 m is quite large relative to the 

distances to the observation wells (23 m and 37 m). 

Frequently, the dispersivity is approximately 

10 percent of the length scale (Appelo and Postma, 

1993, p. 362–363), which would be about 3 m in this 

case. A large dispersivity can be considered as a lack 

of knowledge about individual flow paths within an 

aquifer (Appelo and Postma, 1993). Additional flow 

paths would result if each productive zone were 

divided into more layers. To allow for a wider range of

V θh πr

2 = ( ),

V

θ

h

π

r

θh
Reactive-Transport Simulations 39

Figure 23. Schematic diagram showing aquifer 

geometry used to simulate chloride transport for 

cycle 3 of the aquifer storage recovery study in 

Charleston, South Carolina.

possibilities for simulating transport in the aquifer, two productive zones containing two 2-m layers each, were used for estimating the flow-model parameters and in all simulations of 

reactive transport. As discussed earlier, leakage was assumed to 

be negligible. A schematic for the aquifer geometry used in 

reactive-transport simulations is shown in figure 23. The water 

composition in a well that penetrated a productive zone was calculated as a mixture of waters from the model layers that represented the productive zone. The mixture of waters was 

determined by the well flow rates for the layers of the productive 

zone.

transmissivity estimated by fitting the drawdown data with 

analytical methods. The longitudinal dispersivity is 0.5 m for all 

layers; transverse dispersivity is 0.05 m.

The transport simulations for chloride include dispersion 

that results from the specified dispersivity (0.5 m) and also 

numerical dispersion that results from time and space 

discretization for the finite difference approximations. When 

using upstream in space and backward in time weighting for the 

finite difference equations, the numerical dispersivity can be 

approximated by the formula:

D = ∆ X / 2 + V ∆ t / 2, (2)

where 

is the numerical dispersivity, in meters;

is the node spacing, in meters;

is the velocity in the X direction, in meters per day; 

and 

is the time step for the simulation, in days. 

In the reactive-transport simulations was 2.5 m and 

was 0.1 day during the injection period. The simulated velocity 

was large near the injection well, approximately 30 m/d during 

injection, but decreased with distance from the injection well. 

Thus, numerical dispersivity was approximately 3 m at the 

pumping well during injection, but approached 1.5 m with 

distance from the injection well. During recovery, the simulated 

velocity was approximately 125 m/d at the pumping well, but a 

time step of 0.01 day was used for the initial 10 days of 

recovery, which limited the range of the numerical dispersion 

from 1.5 to 2.5 m. The specified dispersivity for the simulations 

was 0.5 m. Except near the injection and pumping well, the 

effective dispersivity was about 2 m (sum of specified and 

numerical dispersivities). 

The simulated chloride concentrations for the three wells, 

computed by using the adjusted porosities and dispersivity, 

match the measured chloride concentrations adequately 

(fig. 24). Simulated chloride concentration during storage at 

well CHN-812 was 23 mg/L, which is lower than the first 

measured concentration during recovery (40 mg/L). However, a 

lower simulated value for storage is not necessarily inconsistent 

D

∆X

V

∆t

∆X ∆t

Porosity and dispersivity for the four model layers were 

adjusted by trial and error to account for the time sequence 

during ASR cycle 3 of chloride concentrations. Observations 

included data for observation wells CHN-809 and CHN-810 

throughout ASR cycle 3 and for pumping well CHN-812 during 

recovery. The set of hydraulic and transport parameters for the 

four aquifer layers are given in table 8. The transmissivity 

calculated from the horizontal hydraulic conductivities and 

layer thicknesses is 33.8 m2

/d, which is similar to the 

Table 8. Flow and transport model parameters selected for reactive-transport simulations during the aquifer storage recovery 

study in Charleston, South Carolina.

[UPZ, upper productive zone; LPZ, lower productive zone]

Layer Thickness 

(meter)

Specific 

storage

(1/meter)

Horizontal 

hydraulic 

conductivity

(meter per day)

Vertical 

hydraulic 

conductivity

(meter per day)

Porosity

(unitless)

Longitudinal 

dispersivity

(meter)

UPZ, upper layer 2 1.5x10-5 8.4 0.84 0.1 0.5

UPZ, lower layer 2 1.5x10-5 2.5 .25 .3 .5

LPZ, upper layer 2 1.5x10-5 1 .1 .3 .5

LPZ, lower layer 2 1.5x10-5 5 .5 .1 .5
40 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

Figure 24. Measured chloride concentrations and chloride concentrations simulated by using two 2-meter 

layers for each production zone and adjusted porosity and hydraulic conductivity during the aquifer storage 

recovery study in Charleston, South Carolina.

with the measured concentration because the first sample was 

not taken immediately upon initiation of pumping. 

There is no assurance that the selected flow and transport 

model parameters uniquely produce the goodness of fit for 

chloride concentrations that are shown in figure 24. Other 

parameter options that include different layer thicknesses, 

porosities, hydraulic conductivities, and dispersivities may 

produce equally good or better simulations. However, the 

adjusted parameters are plausible—the thicknesses of the 

productive zones are consistent with well logs; the UPZ has a 

higher transmissivity, as indicated by well flow logs; and 

horizontal hydraulic conductivity, porosity, and specific storage 

are reasonable for a Coastal Plain aquifer, although porosity in 

the higher hydraulic conductivity layers (0.1) is somewhat less 

than expected. The porosity could be increased if the thickness 

of the higher hydraulic conductivity layers were decreased. 

Simulations using the selected flow and transport model 

parameters adequately match the drawdown data of the aquifer 

tests, the chloride concentration data for the observation wells, 

and the chloride concentration data for the recovered water. 
Reactive-Transport Simulations 41

These flow and transport model parameters are assumed to 

adequately describe flow and transport in the SL/BM aquifer 

and are used to investigate geochemical reactions and the 

response of the aquifer to long-term injection and storage of 

water.

Chemical Reactions

Results of inverse geochemical modeling indicate that 

mixing (dispersion), cation exchange, and calcite dissolution 

and precipitation account for the evolution of water chemistry 

during the ASR investigation. For reactive-transport 

simulations, the simplest assumption is that the cationexchange and calcite reactions are equilibrium controlled; that 

is, the kinetics of these reactions are sufficiently rapid to attain 

equilibrium. For the reactive-transport simulations, the 

equilibrium constants for calcite and cation exchange were 

taken from the phreeqc.dat database (Parkhurst and Appelo, 

1999); all aqueous species and equilibrium constants also were 

taken from phreeqc.dat. 

For the reactive-transport simulations, data are needed for 

the number of moles of calcite and exchange sites per liter of 

water. For calcite, the minimum abundance from table 1 is 

19 percent, or 0.19 kilogram (kg) of calcite per kilogram of 

sediment. Assuming a porosity of 0.3, a density of the solid 

sediment of 2.7 kg/L, and a formula weight of 100 grams per 

mole (g/mol) for calcite, the number of moles of calcite per liter 

of water is (0.19 x 1,000 /100) x 2.7 x 0.7/0.3 = 12 moles per 

liter (mol/L) water. This amount is sufficient to maintain calcite 

equilibrium for hundreds of pore volumes, and the simulations 

are insensitive to the exact abundance of calcite. An estimate of 

the cation exchange capacity (CEC) is 22 meq/100 g sediment 

(table 1). By using the same porosity and density, the number of 

exchange sites is estimated to be (22/1,000/100 x 1,000) x 2.7 x 

0.7/0.3 = 1.4 equivalents per liter (eq/L) of water. However, the 

CEC varied from 0 to 36 meq/100 g in samples from the aquifer, 

and simulations are sensitive to the number of exchange sites. 

The number of exchange sites per liter of water was used as an 

adjustable parameter to produce a match between simulated and 

measured cation concentrations.

For all simulations, the aquifer was initially filled with 

brackish aquifer water (table 5). Water entering the simulation 

region from the boundaries also had the composition of the 

brackish aquifer water. Injected water had the composition 

defined in table 5. ASR cycle 3 was simulated with 43 days of 

injection at a rate of 0.11 m3

/min, 99 days of storage, and 

48 days (actual was 61 days) of recovery at a pumping rate of 

0.456 m3

/min (7.57 L/s). Because one quadrant of the aquifer 

was simulated, injection and pumping rates were reduced by a 

factor of four for the simulations.

The concentration of exchange sites that produced the best 

fit for all constituents was approximately 0.1 meq/L water.

Simulation results for wells CHN-812 and CHN-809 are shown 

in figures 25 and 26, respectively.

If the concentration of exchange sites was an order of 

magnitude higher (1.0 eq/L water), the simulated calcium 

concentration at the start of recovery at well CHN-812 

(approximately 10 mg/L) was lower than the measured 

concentrations (approximately 25 mg/L). Some of the 

difference in calcium concentration at the pumping well (CHN812) also may have been caused by disequilibrium between 

solution and exchange sites in the rapid-flow environment near 

the pumping well. For well CHN-809, if the concentration of 

exchange sites was an order of magnitude lower (0.01 eq/L 

water), the simulated calcium concentrations during storage 

were too high (approximately 10 mg/L compared with less than 

5 mg/L measured), the simulated alkalinity was too low (100 to 

200 mg/L compared with 300 mg/L measured), and the 

simulated pH was too low (approximately 8.0 compared with 9 

to 10 measured). In simulation results with the lower 

concentration of exchange sites (0.01 eq/L water), calcium 

concentrations had begun to increase at observation well CHN809. However, in ASR cycle 3, no breakthrough of calcium at 

observation well CHN-809 was observed, which implies that 

the number of exchange sites must be greater than 0.01 eq/L 

water. During the course of a longer injection, observation of a 

calcium breakthrough of approximately 20 mg/L (fig. 27), 

would allow a more accurate estimation of the number of 

exchange sites in the productive zones and would help to 

discriminate between concentration of exchange sites and 

kinetic effects near the pumping well.
42 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

Figure 25. Measured concentrations of major ions and pH for production well CHN-812 during cycle 3, and concentrations simulated by using the adjusted flow and transport parameters and a value of 0.1 equivalent per liter of water for the 

concentration of exchange sites during the aquifer storage recovery study in Charleston, South Carolina.
Reactive-Transport Simulations 43

Figure 26. Measured concentrations of major ions and pH for observation well CHN-809 during cycle 3 and concentrations 

simulated by using the adjusted flow and transport parameters and a value of 0.1 equivalent per liter of water for the concentration of exchange sites during the aquifer storage recovery study in Charleston, South Carolina.
44 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

Figure 27. Simulated concentrations of cations and amount of calcite reacted with distance from production well 

CHN-812 at the end of the cycle-3 injection period during the aquifer storage recovery study in Charleston, South 

Carolina.
Reactive-Transport Simulations 45

Figure 28. Measured chloride concentrations for cycle 3 and simulated chloride concentrations during recovery 

following injection periods 1, 2, 4, and 8 times the 43-day injection for cycle 3 during the aquifer storage recovery 

study in Charleston, South Carolina.

Aquifer Storage Recovery

The calibrated reactive-transport model was used to assess 

the effectiveness of long-term storage and recovery by 

simulating the amount of potable water that could be recovered 

for varying lengths of injection. The model also was used to 

estimate the effect on porosity caused by the dissolution and 

precipitation of calcite during ASR. Finally, an additional 

simulation was performed to determine the effect of a regional 

hydraulic gradient on the movement of the injected water.

Recoverable Potable Water

To estimate the amount of potable water that could be 

recovered with extended injection periods, four simulations 

were performed using durations of 1, 2, 4, and 8 times the 

duration of injection for ASR cycle 3. In the longest simulation, 

water was injected for approximately 1 year (344 days). In all 

simulations, water was injected at 0.11 m3

/min (1.89 L/s) and 

recovered at a pumping rate of 0.45 m3/min (7.57 L/s). Potable 

water was defined as water with a chloride concentration less 

than 250 mg/L. Simulated storage times were variable, but the 

length of the storage period had no effect on the simulated 

recoveries. The chloride concentrations during recovery in the 

four simulations are shown in figure 28. For successively longer 

injection periods, the duration of recovery of potable water 

increases from 3.5 to 28 days. The length of time and the 

volume of potable water that can be recovered are essentially 

linear with the length of injection. In all cases, the recovery 

efficiency is approximately 0.3; that is, 30 percent of the 

volume of injected water can be recovered before chloride 

concentrations exceed 250 mg/L. In the simulation using the 

344-day injection period, approximately 56,000 m3

 (15 million 

gallons [Mgal]) of water were injected and 18,000 m3

(4.8 Mgal) of potable water were recovered. Simulated results 
46 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

compare very well with average recovery efficiencies 

determined throughout this investigation (21 to 34 percent). The 

43-day simulation appears to overestimate the volume of 

potable water compared to the measured chloride 

concentrations for ASR cycle 3 (fig. 28). A more conservative 

recovery efficiency is 25 percent. The observations and 

simulations indicate that at least four times the target volume of 

water needs to be injected to be able to successfully recover the 

target volume of potable water. 

Effects of Injection on Porosity

Simulations assuming equilibrium indicate that calcite 

dissolves and precipitates in response to a complex series of 

cation-exchange reactions. The amount of calcite that reacted 

(negative indicates dissolution and positive indicates 

precipitation) in the high hydraulic conductivity layer of the 

UPZ during the simulation of the ASR cycle-3 injection is 

shown in figure 27. In the simulation, calcite dissolved to the 

greatest extent in the vicinity of the injection well and 

precipitated between 30 and 50 m from the well. Calcite 

dissolution (negative value, fig. 27) is greatest at the injection 

well (X = 0 m). Calcite dissolution is also greater at 18 m than 

at any other distance between 6 m and 50 m from the injection 

well. This pattern of calcite reaction is caused by an injection 

water that is undersaturated with respect to calcite and cation 

exchange reactions in the aquifer. Thus, the injected water 

dissolves calcite near the injection well. However, the calcium, 

derived from the injected water and dissolution of calcite, 

interacts with cations exchanged on the clays (and zeolites) of 

the aquifer. Cation exchange causes an uptake of calcium, and 

a release of sodium, magnesium, and potassium. The 

simulations indicate a potassium peak at about 15 m from the 

injection well after the 43-day injection (fig. 27). A magnesium 

peak at about 12 m follows the potassium peak, which in turn is 

followed by high calcium concentrations. Dissolution and 

precipitation of calcite respond to these cation interactions with 

the sediments; where calcium is exchanged for magnesium and 

potassium (approximately 12 to 18 m), calcite tends to dissolve. 

Calcite precipitated between 30 and 50 m from the injection 

well, which is the beginning of the mixing zone between the 

injected water and the brackish aquifer water. Thus, there are 

cation concentration fronts and calcite dissolution and 

precipitation fronts that are predicted to proceed through the 

aquifer as injection of water proceeds.

The volume of calcite, in millimoles per liter, that 

dissolved in water is minor (fig. 27). Given the porosity of 

10 percent for the high hydraulic conductivity layer that was 

used in the simulations, the change in porosity caused by 

dissolution of 25 mmol/L calcite is approximately 0.01 percent. 

Similarly, the amount of calcite precipitated in the calcite 

precipitation front causes a negligible decrease in porosity. 

Simulated results indicate that the maximum porosity increase 

after 100 years of injection is 0.1 percent in cells in the vicinity 

of the injection well.

Effects of a Regional Hydraulic Gradient 

One additional simulation was performed to investigate 

the effects of a regional hydraulic gradient on storage and 

recovery. From the potentiometric surface contours given in 

Campbell and others (1997), a regional hydraulic gradient 

toward pumping centers in the northern part of the peninsula is 

approximately 0.0005 meter per meter (m/m). 

A second model was developed that applied the regional 

hydraulic gradient as boundary conditions such that the 

potentiometric surface of the initial condition sloped downward 

from southeast to northwest. Leaky boundary conditions 

imposed this regional hydraulic gradient. The simulation region 

was centered on production well CHN-812 (fig. 29) and was 

discretized in the X and Y directions with variable but 

increasing spacing of nodes. Grid discretization ranged from 

5 m near well CHN-812 to a maximum of 500 m at the margins 

of the simulation region and represented an area of 10,000 m by 

10,000 m. Vertical layering was discretized into two productive 

zones containing two 2-m layers each (fig. 23). Flow and 

transport model parameters for this model were equal to those 

of the reactive-transport model previously discussed (table 8).

A 100-year simulation of constant injection at 0.11 m3/min 

(30 gal/min) was performed to investigate the short- and longterm effects of the regional hydraulic gradient. The following 

discussion considers the most hydraulically conductive layer in 

the simulation; other layers with lower hydraulic conductivity 

will have smaller extents of freshwater and lower flow 

velocities.

After 1 year of simulation, the freshwater (based on the 

location of the 250-mg/L chloride contour) migrated 

approximately 100 m from the injection well and was 

essentially circular (fig. 29). The steep gradients from the 

injection well to the aquifer caused radial flow and completely 

overwhelmed any effect from the relatively shallow regional 

hydraulic gradient. After 10 years the freshwater migrated 

approximately 300 m from the injection well, and the shape of 

the 250-mg/L chloride contour was only slightly asymmetric. 

By 100 years, the simulated 250-mg/L chloride contour was 

substantially asymmetrical around the injection well, which 

was caused by the regional hydraulic gradient; the freshwater 

contour extended 800 m from the injection well upgradient and 

1,200 m downgradient. 

The simulated steady-state velocity configuration for the 

specified injection rate, flow-model parameters, and imposed 

regional hydraulic gradient, which was achieved in less than 

1 year, had a stagnation point (location where flow velocities 

are zero) about 1,500 m upgradient from the injection well. 

Freshwater will never advance past the stagnation point, 

regardless of the length of injection, and the maximum extent of 

the 250 mg/L contour will be less than 1,500 m (800 m is the 

maximum extent in 100 years). The extent of freshwater flow in 

the downgradient direction was limited only by the length of the 

injection period. For practical time periods (decades) and 

reasonable injection rates (0.11 m3/min), the maximum extent 
Reactive-Transport Simulations 47

Figure 29. Extent of freshwater migration after 1, 10, and 100 years of injection at the aquifer storage recovery site, Charleston, South

Carolina.

of the freshwater bubble from a single injection was less than 

1 km and nearly symmetrical.

If injection ceases, the regional hydraulic gradient will be 

reestablished rapidly and the movement of the freshwater 

bubble can be estimated from Darcy’s law:

v = K (dh /dl) / θ , (3)

where

is the interstitial velocity, in meters per day;

is the hydraulic conductivity, in meters per day;

dh/dl is the hydraulic gradient, in meters per meter; and

is the porosity of the aquifer, unitless. 

v

K

θ

Using K = 8.4 m/d, dh/dl = 0.0005 m/m, and θ = 0.1, groundwater velocity resulting from the regional hydraulic gradient is 

about 0.04 m/d or 15 meters per year (m/yr). 

After development of the regional hydraulic gradient 

model, input flow and transport parameters were varied to 

evaluate the sensitivity of the location of the simulated 250-

mg/L chloride contour to four model inputs. The simulated 

distance from the injection well to the 250-mg/L chloride 

contour increases as the porosity used in the model is decreased 

because a larger volume of aquifer is needed to contain the same 

volume of injected water. The simulated distance to the 

250 mg/L contour is maximized when the dispersivity used in 

the model is zero, and is decreased as dispersivity is increased. 

The simulated distance to the 250 mg/L contour is independent 
48 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

of the hydraulic conductivity provided the ratios of hydraulic 

conductivity are preserved among all the layers of the model. If 

the ratio of hydraulic conductivity between two layers is 

changed, the location of the contour will depend on the relative 

proportion of water transmitted by the layers and the porosities 

of the layers. The 250 mg/L contour is insensitive to the specific 

storage used in the model.

Summary

The hydrologic and geochemical effects of aquifer storage 

recovery were evaluated to determine the potential for 

supplying the city of Charleston, South Carolina, with large 

quantities of potable water during emergencies. Estimates 

presented in a 2001 South Carolina Emergency Preparedness 

Division report are that 80 percent of the homes in the 

Charleston area would be without water for weeks to months 

because of damaged water pipes following an earthquake of 

similar magnitude (7.3) to the 1886 Charleston earthquake. To 

evaluate the feasibility of aquifer storage recovery as a source 

of drinking water after an earthquake, hurricane, or hard freeze, 

an aquifer storage recovery system, including a production well 

and three observation wells, was installed at a site located on the 

Charleston peninsula. The focus of this study was the 23.2-

meter thick Tertiary limestone and sand aquifer of the Santee 

Limestone and the Black Mingo Group. 

The investigation included geophysical logging of wells, 

aquifer testing, monitoring long-term water levels and waterquality characteristics, and evaluating water-quality data by 

using geochemical models. Geophysical logging was used to 

investigate the hydrogeologic features of the Santee 

Limestone/Black Mingo aquifer and to evaluate the transport of 

treated surface water within the aquifer. Two aquifer tests were 

completed to determine the Santee Limestone/Black Mingo 

aquifer properties surrounding the production well and to 

determine if the properties changed with successive aquifer 

storage recovery cycles. Long-term water-level monitoring and 

analyses of water-quality samples during four injection, 

storage, and recovery cycles were used to evaluate the trends in 

injection and withdrawal rates, recovery efficiency, and longterm storage effects on the injectant water quality. Finally, 

geochemical modeling was used to determine the dominant 

chemical reactions and hydraulic processes that affect the 

injectant water quality during the aquifer storage recovery tests.

Analysis of six sediment samples collected from a cored 

well located near the aquifer storage recovery site showed that 

quartz and calcite are the dominant minerals in the Santee 

Limestone/Black Mingo aquifer. Opal, clinoptilolite, 

ferruginous illite, and smectite were present in quantities of 

more than 7 percent by weight in the lower production zone and 

lower permeable zone located between the upper and lower 

production zones. Ankerite, a calcium carbonate and member of 

the dolomite group, was present only in the lower permeable 

section and composed 9 percent of the sample by weight. 

Estimated cation exchange capacity ranged from 12 to 

36 milliequivalents per 100 grams in the lower section of the 

aquifer.

Formation resistivity logs, borehole electromagnetic flowmeter logs, and specific-conductance profiles were collected in 

the observation wells to delineate the dominant production 

zones of the Santee Limestone/Black Mingo aquifer. All three 

methods delineated a 2- to 3- meter thick upper production zone 

at depths from about 111 and 115 meters below land surface. 

Formation resistivity and electromagnetic flow-meter logs 

delineated at least a 3- to 4-meter thick lower production zone 

at depths from about 128 and 134 meters below land surface. 

Borehole electromagnetic flow-meter results while injecting 

into well CHN-809 indicated that the upper, middle, and lower 

screen sections received total flow of 58, 1, and 41 percent, 

respectively.

Two aquifer tests were conducted during this investigation 

to determine the hydraulic characteristics of the Santee 

Limestone/Black Mingo aquifer and if the characteristics 

changed as a result of aquifer storage recovery testing. 

Analytical results of the two aquifer tests indicated that aquifer 

properties did not change as a result of aquifer storage recovery 

cycling. Transmissivity values of the two tests were equal at 

37 meters squared per day. The average storage coefficient of 

the Santee Limestone/Black Mingo aquifer was 3 x 10-5. The 

leakage coefficient of the confining unit was estimated to be 

less than 7 x 10-4 meter-1; however, analytical results of tests 

that did not allow leakage produced a sum of squares error 

similar to the original results, indicating that leakage into the 

Santee Limestone/Black Mingo aquifer is minimal. Differences 

in the storage coefficient and the maximum leakage values for 

the two aquifer tests are minimal and could be due to the 

insensitivity of the analytical solution to the leakage factor. The 

consistent results between the two aquifer tests indicate that 

physical changes to the Santee Limestone/Black Mingo aquifer 

because of calcite dissolution or other geochemical reactions 

have little effect on the hydraulic properties of the Santee 

Limestone/Black Mingo aquifer. 

Specific-capacity data from the June 1999 (0.12 liter per 

second per meter of drawdown) and November 2001 

(0.092 liter per second per meter of drawdown) aquifer tests 

indicate that the overall specific capacity decreased over time 

because of residual plugging that occurred within the aquifer or 

well screen. Additional evidence of plugging is the decrease in 

injection rates for aquifer storage recovery cycles 2 through 4, 

even though the same average injection pressure was 

maintained at the production well. Specific-capacity values 

improved following inadvertent pump failure during the cycle4 recovery phase, which indicates that periodic redevelopment 

during the injection cycles could limit the reduction in specific 

capacity during aquifer storage recovery implementation at this 

site.

Four cycles of injection, storage, and recovery were 

conducted between October 1999 and February 2002. Each 
References Cited 49

cycle consisted of injecting between 6.90 and 7.19 million liters 

of water for storage periods of 1, 3, or 6 months. Average 

injection rates varied from 0.82 to 2.0 liters per second; 

recovery rates varied from 7.57 to 8.83 liters per second. The 

volume of recovered water that did not exceed the U.S. 

Environmental Protection Agency secondary standard for 

chloride of 250 milligrams per liter varied from 1.48 to 

2.46 million liters for the four tests.

Recovery efficiencies for this investigation were 

comparable to those during a pilot investigation conducted from 

1993 to 1995 and varied between 21 and 34 percent for the four 

aquifer storage recovery tests. Recovery efficiencies were 

essentially equal for the 3-month (cycle 3) and 6-month (cycle 

4) storage cycles. Solute transport modeling indicated a 

consistent recovery efficiency of approximately 25 percent, 

regardless of length of injection. 

During this investigation, a total of 193 water-quality 

samples were collected and analyzed for physical properties, 

major and minor ions, and nutrients. Forty-five samples were 

collected and analyzed for total trihalomethane. Water-quality 

samples were collected directly from water spigots inline with 

the city water mains and the production well discharge pipe and 

by using a portable piston-driven submersible pump. Samples 

collected during this investigation documented baseline aquifer 

and injectant water quality and changes in the mixed water 

quality during injection, storage, and recovery. 

Total trihalomethane data collected during aquifer storage 

recovery cycle 4 indicated that this constituent would not 

restrict the use of recovered water for drinking-water purposes. 

During recovery, total trihalomethane concentrations decreased 

from 8.5 micrograms per liter to less than detection levels at the 

production well. Comparison of chloroform to chloride 

concentrations in ground-water samples and the absence of 

bromoform, bromodichloromethane, and chlorodibromomethane in all ground-water samples indicate that total 

trihalomethane was nonconservative during aquifer storage 

recovery cycle 4. Total trihalomethane concentrations in 

samples collected from observation wells during storage 

typically were lower than trihalomethane concentrations that 

would occur as a result of mixing of injected and aquifer water. 

The mechanism of trihalomethane reduction was not evaluated 

during this investigation; however, other investigations have 

indicated that mixing and microbial degradation may reduce 

trihalomethane concentrations during storage and recovery. 

During this investigation, treated surface water with totaldissolved-solids concentration of approximately 100 milligrams per liter was injected into the Santee Limestone/Black 

Mingo aquifer with a total-dissolved-solids concentration of 

4,000 milligrams per liter. During the injection period, 

breakthrough of low chloride water at observation well 

CHN-809 constrained the product of porosity times thickness to 

0.8 meter, which is consistent with thin production zones of no 

more than 4 meters each. 

A reactive transport model was developed that included 

two 2-meter thick layers to describe each of the production 

zones. The four layers composing the production zones were 

assigned porosity ranging from 0.1 to 0.3 and hydraulic 

conductivity ranging from 1 to 8.4 meters per day. Specific 

storage of the aquifer and confining units was estimated to be 

1.5 x 10-5 meter-1. Dispersivity of all layers was 0.5 meter. 

Leakage through the confining unit was estimated to be 

minimal—vertical hydraulic conductivity of the confining units 

was 1 x 10-6 meter per day; therefore, leakage was eliminated in 

the reactive transport modeling. The assigned properties 

produced good agreement between measured chloride 

concentrations and simulated chloride concentrations for two 

observation wells during an entire aquifer storage recovery 

cycle and for the recovery well after pumping was initiated.

The aquifer water and treated surface water were sodiumchloride and calcium/sodium-bicarbonate water types, 

respectively. Inverse geochemical modeling indicated that 

mixing, cation exchange, and calcite dissolution were the 

dominant reactions occurring during aquifer storage recovery 

testing in the Santee Limestone/Black Mingo aquifer. Potable 

water injected into the Santee Limestone/Black Mingo aquifer 

evolved chemically by mixing with brackish background water 

and reaction with calcite and cation exchangers in the sediment. 

Reactive-transport model simulations indicate that the calcite 

and exchange reactions can be treated as equilibrium processes. 

By adjustment of the number of cation exchange sites per liter 

of water, good agreement was obtained between measured 

concentrations of major ions and pH and simulated values for 

observation and recovery wells.

Simulations with the calibrated reactive transport model 

indicated that approximately one-fourth of the water injected 

into the aquifer can be recovered as potable water, regardless of 

the length of the injection period. Simulations indicate that 

calcite dissolves near the injection well and precipitates where 

freshwater and brackish water mix during injection. However, 

the amounts of calcite dissolved and precipitated have a 

negligible effect on the porosity of the aquifer and should not 

affect the flow of water during aquifer storage recovery. 

Finally, simulations indicated that the regional configuration of 

the potentiometric surface in the aquifer had a negligible effect 

on the storage of water. Potable water was distributed 

symmetrically around an injection well even in the presence of 

a regional hydraulic gradient of about 0.0005 meter per meter in 

the aquifer. When injection ceased, the regional hydraulic 

gradient was reestablished and the freshwater bubble moved at 

a ground-water velocity of approximately 15 meters per year.

References Cited

Appelo, C.A.J., and Postma, D., 1993, Geochemistry, 

groundwater and pollution: Rotterdam, A.A. Balkema, 536 p.

Aucott W.A., and Newcome, Roy, Jr., 1986, Selected aquifertest information for the Coastal Plain aquifers of South 

Carolina: U.S. Geological Survey Water-Resources 

Investigations Report 86-4159, 30 p.
50 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

Aucott, W.A., and Speiran, G.K., 1985a, Potentiometric 

surfaces of the Coastal Plain aquifers of South Carolina prior 

to development: U.S. Geological Survey Water-Resources 

Investigations Report 84-4208, 5 sheets.

Aucott, W.A., and Speiran, G.K., 1985b, Potentiometric 

surfaces of November 1982 and declines in the 

potentiometric surfaces between the period prior to 

development and November 1982 for the Coastal Plain 

aquifers of South Carolina: U.S. Geological Survey 

Water-Resources Investigations Report 84-4215, 

7 sheets.

Barcelona, M., Wehrmann, H.A., and Varljen, M.D., 1994, 

Reproducible well-purging procedures and VOC 

stabilization criteria for ground-water sampling: Ground 

Water, v. 32, p. 12–22.

Bollinger, G.A., 1977, Reinterpretation of the intensity data for 

the 1886 Charleston, South Carolina, earthquake, in Rankin 

D.W., ed., Studies related to the Charleston, South Carolina, 

earthquake of 1886—A preliminary report: U.S. Geological 

Survey Professional Paper 1028, p. 17–32. 

Brown, D.L., and Silvey, W.D., 1977, Artificial recharge to a 

freshwater-sensitive brackish-water sand aquifer, Norfolk, 

Virginia: U.S. Geological Survey Professional Paper 939, 

53 p. 

Bybell, L.M., Conlon, K.J., Edwards, L.E., Frederiksen, N.O., 

Gohn, G.S., and Self-Trail, J.M., 1998, Biostratigraphy and 

physical stratigraphy of the USGS-Cannon Park core (CHN800), Charleston County, South Carolina: U.S. Geological 

Survey Open-File Report 98-0246, 65 p.

Campbell, B.G., Conlon, K.J., Mirecki, J.E., and Petkewich, 

M.D., 1997, Evaluation of aquifer storage recovery in the 

Santee Limestone/Black Mingo aquifer near Charleston, 

South Carolina, 1993–95: U.S. Geological Survey WaterResources Investigations Report 96-4283, 89 p.

Campbell, B.G., and Gohn, G.S., 1994, Stratigraphic 

framework for geologic and geohydrologic studies of the 

subsurface Cretaceous section near Charleston, South 

Carolina: U.S. Geological Survey Miscellaneous Field 

Investigations 2273, 2 sheets.

Chapelle, F.H., and Knobel, L.L., 1985, Stable carbon isotopes 

of HCO3

-

 in the Aquia aquifer, Maryland — Evidence for an 

isotopically heavy source of CO2: Ground Water, v. 23, 

no. 5, p. 592–599.

Charleston Commissioners of Public Works, 2003, Charleston 

CPW System—Table 1 Regulated Compounds: accessed 

April 21, 2003, at http://www.charlestoncpw.com/

wq5.html

Ford, W.E., 1949, Dana’s textbook of mineralogy (4th ed.): 

New York, John Wiley & Sons, Inc., 51 p.

Fronabarger, A.K., Katuna, M.P., and Conlon, K.J., 1995, 

Biostratigraphic and lithostratigraphic analyses of the 

Cooper Group (upper Eocene to upper Oligocene) within 

the lower Coastal Plain of South Carolina: Geological 

Society of America Abstracts with Programs, v. 27, no. 2, 

p. 54.

Gibs, Jacob, and Wilde, F.D., 1998, Ground-water sampling: 

Preparations and purging methods at water-supply wells and 

monitoring wells, in National field manual for the collection 

of water-quality data: U.S. Geological Survey Techniques of 

Water-Resources Investigations, book 9, chap. A4.2: 

accessed September 11, 2003, at http://water.usgs.gov/owq/

FieldManual/chapter4/html/4.2_contents.html

Gohn, G.S., Higgins, B.B., Smith, C.C., and Owens, J.P., 1977, 

Lithostratigraphy of the deep corehole (Clubhouse 

Crossroads Corehole 1) near Charleston, South Carolina; in

Rankin, D.W., ed., Studies related to the Charleston, South 

Carolina, earthquake of 1886—A preliminary report: U.S. 

Geological Survey Professional Paper 1028, p. 59–70. 

Halford, K.J., and Campbell, B.G., 2004, A unique approach to 

estimating lateral anisotropy in complex geohydrologic 

environments: Journal of Hydraulic Research, v. 42, Extra 

Issue, p. 77–81.

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

Geological Survey Water-Supply Paper 2220, 84 p.

Hem, J.D., 1985, Study and interpretation of the chemical 

characteristics of natural water (3d ed.): U.S. Geological 

Survey Water-Supply Paper 2254, 263 p.

Heron, S.D., Jr., 1969, Mineralogy of the Black Mingo 

mudrocks: South Carolina State Development Board, 

Division of Geology, Geologic Notes, v. 13, no. 1, 

p. 27– 41.

Hockensmith, B.L., 2001, Potentiometric map of the Floridan 

aquifer and Tertiary sand aquifer in South Carolina—1998: 

South Carolina Department of Natural Resources Water 

Resources Report 23, 1 pl.

McCartan, Lucy, Weems, R.E., and Lemon, E.M., Jr., 1980, 

The Wando Formation (Upper Pleistocene) in the 

Charleston, South Carolina, area, in Sohl, N.F., and Wright, 

W.B., Changes in stratigraphic nomenclature by the U.S. 

Geological Survey, 1979: U.S. Geological Survey Bulletin 

1502-A, p. A110 –A116.

Meadows, J.K., 1987, Ground-water conditions in the Santee 

Limestone and Black Mingo Formation near Moncks Corner, 

Berkeley County, South Carolina: South Carolina Water 

Resources Commission Report 156, 38 p.

Merritt, M.L, 1985, Subsurface storage of freshwater in 

south Florida—A digital model analysis of recoverability: 

U.S. Geological Survey Water-Supply Paper 2261, 

44 p. 

Mirecki, J.E., Campbell, B.G., Conlon, K.J., and Petkewich, 

M.D., 1998, Solute changes during aquifer storage recovery 

in a limestone/clastic aquifer: Ground Water, v. 36, no. 6, 

p. 394 – 403. 

Moench, A.F., 1985, Transient flow to a large-diameter well in 

an aquifer with storative semiconfining layers: Water 

Resources Research, v. 21, no. 8, p. 1121–1131.

Newcome, Roy, Jr., 1993, Pumping tests of the Coastal Plain 

aquifers in South Carolina with a discussion of aquifer and 

well characteristics: South Carolina Water Resources 

Commission Report Number 174, 52 p.
References Cited 51

Park, A.D., 1985, The ground-water resources of Charleston, 

Berkeley, and Dorchester Counties, South Carolina: South 

Carolina Water Resources Commission Report Number 139, 

145 p.

Parkhurst, D.L., and Appelo, C.A.J., 1999, User’s guide to 

PHREEQC (Version 2)—A computer program for 

speciation, batch-reaction, one-dimensional transport, and 

inverse geochemical calculations: U.S. Geological Survey 

Water-Resources Investigations Report 99-4259, 312 p.

Parkhurst, D.L., Engesgaard, Peter, and Kipp, K. L., 1995, 

Coupling the geochemical model PHREEQC with a 3D 

multi-component solute-transport model, in V.M. 

Goldschmidt Conference, State College, Pa.: 1995, Program 

and Abstracts, p. 77–78.

Parkhurst, D.L., and Kipp, K.L., 2002, Parallel processing for 

PHAST—A three-dimensional reactive-transport simulator, 

in Hassanizadeh, S.M., Schotting, R.J., Gray, W.G., and 

Pinder, G.F., eds., Developments in water science — 

Computational methods in water resources: Amsterdam, 

Elsevier, no. 47, v. 1, p. 711–718.

Poeter, E.P., and Hill, M.C., 1999, UCODE, a computer code 

for universal inverse modeling: Computers in Geosciences, 

v. 25, p. 457– 462.

Purvis, J.C., 1989, Hurricane Hugo (1989): South Carolina 

Water Resources Commission, State Climatology Series 

Report Number G-37, 82 p.

Pyne, R.D.G., 1995, Groundwater recharge and wells, a guide 

to aquifer storage recovery: Boca Raton, Fla., Lewis 

Publishers, 376 p.

Reese, R.S., 2002, Inventory and review of aquifer storage and 

recovery in southern Florida: U.S. Geological Survey WaterResources Investigations Report 02-4036, 56 p.

Schlumberger Limited, 2003, Oilfield glossary, 

montmorillonite: accessed June 25, 2003, at 

http://www.glossary.oilfield.slb.com/Display.cfm?Term=

montmorillonite

Sloan, Earle, 1908, Catalog of mineral localities of South 

Carolina: South Carolina Geological Survey Bulletin 2, 

451 p.

Sniegocki, R.T., 1963, Problems of artificial recharge through 

wells in the Grand Prairie region, Arkansas: U.S. Geological 

Survey Water-Supply Paper 1615-F, 25 p.

South Carolina Emergency Preparedness Division, 2001, 

Comprehensive seismic risk and vulnerability study for the 

state of South Carolina: accessed February 2, 2004, at 

http://www.state.sc.us/emd/library/eq_study.pdf

Srodon, Jan, Drits, V.A., McCarty, D.K., Hsieh, J.C.C., and 

Eberl, D.D., 2001, Quantitative mineral analysis by powder 

X-ray diffraction from random preparations: Clays and Clay 

Minerals, v. 49, p. 514 –528.

Thomas, J.M., McKay, W.A., Cole, Erin, Landmeyer, J.E., and 

Bradley, P.M., 2000, The fate of haloacetic acids and 

trihalomethanes in an aquifer storage and recovery program, 

Las Vegas, Nevada: Ground Water, v. 38, no. 4, p. 605–614.

U.S. Environmental Protection Agency, 1995, Low-flow 

(minimal drawdown) ground-water sampling procedures: 

EPA Ground Water Issue, EPA/540/S-98/504.

U.S. Environmental Protection Agency, 1996, Low stress (low 

flow) purging and sampling procedure for the collection of 

ground water samples from monitoring: SOP #: GW 0001, 

July 30, 1996 (Rev. 2).

U.S. Environmental Protection Agency, 1988, Methods for the 

determination of organic compounds in drinking water, 

Rev. 2.1, Method 502.2: U.S. Environmental Protection 

Agency, EPA 600/4-88/039.

U.S. Environmental Protection Agency, 2000, Maximum 

contaminant levels (Part 143, National secondary drinkingwater regulations): U.S. Code of Federal Regulations, Title 

40, parts 100 to 149, revised July 1, 2000, p. 612– 614.

U.S. Environmental Protection Agency, 2002, National primary 

drinking water standards: accessed June 24, 2003, at 

http://www.epa.gov/safewater/consumer/mcl.pdf

Ward, L.W., Blackwelder, B.W., Gohn, G.S., and Poore, R.Z., 

1979, Stratigraphic revision of Eocene, Oligocene and lower 

Miocene formations of South Carolina: Geologic Notes, 

v. 23, no. 1, p. 2–23.

Weems, R.E., and Lemon, E.M., Jr., 1984, Geologic map of the 

Mount Holly quadrangle, Berkeley and Charleston Counties, 

South Carolina: U.S. Geological Survey Geologic 

Quadrangle Map GQ-1579, scale 1:24,000.

Wehmiller, J.F., and Belknap, D.F., 1982, Amino acid age 

estimates, Quaternary Atlantic Coastal Plain — Comparison 

of U-series dates, biostratigraphy, and paleomagnetic 

control: Quaternary Research, v. 18, p. 311–336.
52 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer
Appendixes
54 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. [m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; ANC, acid neutralizing capacity; CaCO3, calcium carbonate; ---, data not available; E, estimated; TDW, treated drinking water; NA, not applicable; <, less than; μg/L, microgram per liter; M, presence verified, but not quantified] Sample location (fig. 1; table 2) Sample depth, m bls Date/time (EST) Laboratory pH (su) Laboratory specific conduc- tance 

(μS/cm)

Calcium, 

dissolved 

(mg/L)

Magnesium, 

dissolved 

(mg/L)

Potassium, 

dissolved 

(mg/L)

Sodium, 

dissolved 

(mg/L)

ANC 

(mg/L as 

CaCO3)

Chloride, 

dissolved 

(mg/L)

Fluoride, 

dissolved 

(mg/L)

Silica, 

dissolved 

(mg/L)

Sulfate, 

dissolved 

(mg/L)

Sulfide, 

total 

(mg/L)

Cycle 1

CHN-809 129 11/8/99 

14:18

8.4 6,520 19 25 42 1,360 694 1,540 2.7 39 250 ---

CHN-809 129 12/3/99 

13:49

8.6 3,880 8.9 12 25 770 487 830 4.8 29 160 ---

CHN-809 116 12/3/99 

16:33

8.5 3,150 6.0 8.2 21 630 417 630 5.4 26 140 ---

CHN-810 129 12/7/99 

13:20

8.5 6,050 16 23 39 1,250 680 1,400 3.0 38 250 ---

CHN-810 112 12/7/99 

15:47

8.6 4,710 10 14 29 990 582 1,030 3.8 33 220 ---

CHN-810 129 1/6/00 

14:01

8.6 2,410 11 15 29 920 543 1,010 4.7 32 190 ---

CHN-810 112 1/6/00 

16:20

8.6 2,580 3.9 5.2 18 530 365 490 6.3 23 120 ---

CHN-809 129 1/12/00 

14:32

8.6 2,750 6.2 8.1 18 580 393 570 3.7 25 120 ---

CHN-809 116 1/12/00 

16:34

8.5 1,870 3.8 5.1 12 410 E309 360 3.8 21 92 ---

TDW NA 1/12/00 

16:34

7.4 189 20 1.7 1.6 7 30 14 0.9 6.4 29 ---

CHN-809 116 2/7/00 

14:15

8.7 2,100 3.8 5.3 14 440 332 390 4.1 21 95 ---

CHN-809 129 2/7/00 

16:35

8.6 2,410 4.8 6.4 16 500 356 480 3.9 23 110 ---

CHN-812 NA 3/7/00 

12:50

8.5 6,880 22 27 42 1,460 728 1,650 2.2 42 260 ---

CHN-809 129 4/6/00 

12:36

8.6 7,130 21 28 42 1,470 773 1,720 2.4 42 270 ---
Appendixes 55

Sample 

location

(fig. 1; 

table 2)

Sample 

depth, 

m bls 

Date/time 

(EST)

Laboratory 

pH 

(su)

Laboratory 

specific 

conductance 

(μS/cm)

Calcium, 

dissolved 

(mg/L)

Magnesium, 

dissolved 

(mg/L)

Potassium, 

dissolved 

(mg/L)

Sodium, 

dissolved 

(mg/L)

ANC 

(mg/L as 

CaCO3)

Chloride, 

dissolved 

(mg/L)

Fluoride, 

dissolved 

(mg/L)

Silica, 

dissolved 

(mg/L)

Sulfate, 

dissolved 

(mg/L)

Sulfide, 

total 

(mg/L)

Cycle 2

CHN-809 116 5/15/00 

10:53

8.6 5,080 12 15 28 1,040 597 1,140 3.4 35 210 ---

CHN-809 129 5/15/00 

12:36

8.6 6,880 13 17 32 1,100 623 1,210 3.4 36 220 ---

TDW NA 5/19/00 

12:49

7.6 202 18 1.5 1.7 12 27 19 1.0 5.9 25 ---

CHN-809 116 5/23/00 

11:04

8.7 2,930 5.2 6.8 19 610 404 580 5.1 25 130 ---

CHN-809 129 5/23/00 

13:09

8.7 3,480 7.2 8.9 22 710 455 720 4.8 28 150 ---

CHN-810 112 5/26/00 

10:57

8.7 4,350 8.6 11 27 900 559 930 4.1 32 200 ---

CHN-810 129 5/26/00 

13:02

8.8 5,670 14 19 37 1,190 674 1,290 3.2 37 240 ---

CHN-810 112 6/15/00 

11:32

8.7 2,320 3.5 4.4 17 490 371 440 6.1 23 110 ---

CHN-810 129 6/15/00 

14:31

8.6 4,120 9.3 12 25 840 521 890 4.9 30 170 ---

CHN-809 112 6/16/00 

11:39

--- --- --- --- --- --- E271 --- --- --- --- ---

CHN-809 129 6/16/00 

13:35

8.9 2,370 6.8 5.8 15 480 388 450 3.6 25 97 ---

CHN-809 112 7/17/00 

11:04

9.0 1,510 2.1 3.2 10 320 306 630 5.0 18 130 ---

CHN-809 129 7/17/00 

12:52

8.9 1,830 2.7 3.6 11 370 335 320 3.8 22 79 ---

CHN-810 112 7/18/00 

10:34

8.7 2,260 3.4 4.3 15 470 354 420 2.0 22 110 ---

CHN-810 129 7/18/00 

12:34

8.6 3,630 7.6 10 23 750 473 750 5.2 28 160 ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; ANC, acid neutralizing capacity; CaCO3, 

calcium carbonate; ---, data not available; E, estimated; TDW, treated drinking water; NA, not applicable; <, less than; μg/L, microgram per liter; M, presence verified, but not quantified]
56 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer Sample location (fig. 1; table 2) Sample depth, m bls Date/time (EST) Laboratory pH (su) Laboratory specific conduc- tance 

(μS/cm)

Calcium, 

dissolved 

(mg/L)

Magnesium, 

dissolved 

(mg/L)

Potassium, 

dissolved 

(mg/L)

Sodium, 

dissolved 

(mg/L)

ANC 

(mg/L as 

CaCO3)

Chloride, 

dissolved 

(mg/L)

Fluoride, 

dissolved 

(mg/L)

Silica, 

dissolved 

(mg/L)

Sulfate, 

dissolved 

(mg/L)

Sulfide, 

total 

(mg/L)

Cycle 2 (Continued)

CHN-812 NA 8/2/00 

13:30

8.8 5,950 25 19 39 1,270 644 1,400 1.8 42 220 ---

CHN-809 112 8/31/00 

11:48

8.5 7,320 21 30 45 1,480 757 1,790 2.3 41 270 ---

CHN-809 129 8/31/00 

13:42

8.5 7,090 20 28 43 1,480 753 1,710 2.4 42 270 ---

CHN-810 112 9/6/00 

10:22

8.6 7,640 23 32 58 1,580 785 1,890 2.4 43 280 ---

CHN-810 129 9/6/00 

12:04

8.6 6,870 21 30 43 1,540 721 1,680 2.2 44 250 ---

Cycle 3

CHN-812 NA 9/11/00 

13:52

8.6 7,140 22 30 44 1,480 760 1,720 2.4 42 270 ---

CHN-809 112 9/12/00 

10:40

8.7 7,220 21 26 40 1,500 751 1,800 1.2 42 280 ---

CHN-809 129 9/12/00 

12:34

8.6 7,220 21 25 41 1,600 749 1,800 2.4 41 280 ---

CHN-810 112 9/14/00 

11:05

8.5 7,220 21 26 41 1,500 745 1,800 2.4 42 280 ---

CHN-810 129 9/14/00 

12:57

8.5 7,210 21 25 40 1,500 751 1,800 2.4 41 280 ---

CHN-809 112 9/15/00 

12:11

8.7 6,200 16 20 37 1,300 677 1,500 1.4 39 250 ---

CHN-809 129 9/15/00 

14:18

8.6 6,570 18 22 36 1,400 700 1,600 1.3 40 260 ---

CHN-809 112 9/19/00 

10:44

8.6 3,690 6.1 7.2 18 770 460 780 2.3 29 170 ---

CHN-809 129 9/19/00 

12:40

8.8 4,880 11 14 27 1,000 550 1,100 1.8 34 210 ---

CHN-810 112 9/20/00 

10:54

8.7 6,760 19 23 38 1,400 721 1,600 2.6 40 270 ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; ANC, acid neutralizing capacity; CaCO3, 

calcium carbonate; ---, data not available; E, estimated; TDW, treated drinking water; NA, not applicable; <, less than; μg/L, microgram per liter; M, presence verified, but not quantified]
Appendixes 57

Sample 

location

(fig. 1; 

table 2)

Sample 

depth, 

m bls 

Date/time 

(EST)

Laboratory 

pH 

(su)

Laboratory 

specific 

conductance 

(μS/cm)

Calcium, 

dissolved 

(mg/L)

Magnesium, 

dissolved 

(mg/L)

Potassium, 

dissolved 

(mg/L)

Sodium, 

dissolved 

(mg/L)

ANC 

(mg/L as 

CaCO3)

Chloride, 

dissolved 

(mg/L)

Fluoride, 

dissolved 

(mg/L)

Silica, 

dissolved 

(mg/L)

Sulfate, 

dissolved 

(mg/L)

Sulfide, 

total 

(mg/L)

Cycle 3 (Continued)

CHN-810 129 9/20/00 

12:45

8.7 7,110 20 24 39 1,500 736 1,700 2.5 41 270 ---

CHN-809 112 9/22/00 

11:45

8.7 2,680 3.5 4.1 13 550 373 530 2.7 25 130 ---

CHN-809 129 9/22/00 

13:33

8.7 4,040 8.2 9.6 23 840 487 920 2.2 31 170 ---

CHN-810 112 9/26/00 

9:55

8.7 5,080 11 14 30 1,100 597 1,100 1.7 35 220 ---

CHN-810 129 9/26/00 

11:39

8.6 6,130 16 20 34 1,300 676 1,500 1.5 38 260 ---

CHN-809 112 10/2/00 

10:53

9.0 1,570 1.9 1.7 11 330 286 260 2.2 20 80 ---

CHN-809 129 10/2/00 

12:55

8.8 2,770 5.2 6.2 16 570 387 560 2.2 26 130 ---

CHN-810 112 10/3/00 

10:35

8.7 3,570 6.2 7.2 22 730 469 750 2.5 28 170 ---

CHN-810 129 10/3/00 

12:30

8.5 5,180 13 15 29 1,100 595 1,200 1.9 35 220 ---

CHN-810 112 10/13/00 

10:40

8.7 2,590 3.8 4.5 16 550 375 510 3.0 24 130 ---

CHN-810 129 10/13/00 

12:51

8.8 4,300 9.5 12 25 900 518 940 2.4 30 190 ---

CHN-809 112 10/23/00 

11:24

9.3 1,130 1.4 1.7 5.6 230 232 170 2.5 17 57 ---

CHN-809 129 10/23/00 

13:34

9.0 1,780 3.3 3.7 10 370 289 330 1.6 23 80 ---

CHN-810 112 10/24/00 

10:54

8.7 2,250 3.5 4.0 13 480 339 430 1.9 22 110 ---

CHN-810 129 10/24/00 

13:12

8.7 3,920 8.7 11 22 810 482 850 2.4 29 170 ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; ANC, acid neutralizing capacity; CaCO3, 

calcium carbonate; ---, data not available; E, estimated; TDW, treated drinking water; NA, not applicable; <, less than; μg/L, microgram per liter; M, presence verified, but not quantified]
58 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer Sample location (fig. 1; table 2) Sample depth, m bls Date/time (EST) Laboratory pH (su) Laboratory specific conduc- tance 

(μS/cm)

Calcium, 

dissolved 

(mg/L)

Magnesium, 

dissolved 

(mg/L)

Potassium, 

dissolved 

(mg/L)

Sodium, 

dissolved 

(mg/L)

ANC 

(mg/L as 

CaCO3)

Chloride, 

dissolved 

(mg/L)

Fluoride, 

dissolved 

(mg/L)

Silica, 

dissolved 

(mg/L)

Sulfate, 

dissolved 

(mg/L)

Sulfide, 

total 

(mg/L)

Cycle 3 (Continued)

CHN-809 112 11/2/00 

11:56

9.3 1,400 2.1 2.6 9.3 290 273 230 2.9 18 68 ---

CHN-809 129 11/2/00 

14:30

9.3 1,740 2.9 3.1 10 360 309 300 1.7 21 82 ---

TDW NA 11/2/00 

14:40

7.8 227 20 2.3 2.4 18 32 23 1.1 7.6 33 ---

CHN-810 112 11/3/00 

11:25

8.8 2,030 2.6 2.8 11 420 325 370 2.0 21 100 ---

CHN-810 112 11/3/00 

11:26

8.8 2,040 2.8 3.0 14 430 323 380 2.0 22 100 ---

CHN-810 129 11/3/00 

13:27

8.6 3,380 6.9 8.2 19 690 440 700 2.6 27 160 ---

CHN-810 129 11/3/00 

13:28

8.8 3,380 7.0 8.4 19 720 438 700 2.6 27 160 ---

CHN-809 112 11/13/00 

12:50

9.2 1,560 2.4 3.3 11 320 286 260 2.9 18 72 ---

CHN-809 129 11/13/00 

14:56

9.1 1,800 2.9 3.6 12 370 304 310 1.7 22 85 ---

CHN-810 112 11/20/00 

12:35

8.8 2,060 2.8 3.0 13 430 327 380 2.0 22 100 ---

CHN-810 129 11/20/00 

14:28

8.7 3,340 6.7 7.9 19 680 437 720 2.6 27 150 ---

CHN-809 112 12/5/00 

12:07

--- --- 2.6 3.5 9.9 330 --- --- --- 19 --- ---

CHN-809 129 12/5/00 

14:20

9.0 1,920 3.2 3.9 11 400 322 360 1.7 22 86 ---

CHN-809 129 12/5/00 

14:21

9.0 1,920 3.2 3.9 12 390 323 350 1.7 22 85 ---

CHN-810 129 12/6/00 

14:43

8.7 3,500 7.2 8.6 20 720 450 770 2.6 28 160 ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; ANC, acid neutralizing capacity; CaCO3, 

calcium carbonate; ---, data not available; E, estimated; TDW, treated drinking water; NA, not applicable; <, less than; μg/L, microgram per liter; M, presence verified, but not quantified]
Appendixes 59

Sample 

location

(fig. 1; 

table 2)

Sample 

depth, 

m bls 

Date/time 

(EST)

Laboratory 

pH 

(su)

Laboratory 

specific 

conductance 

(μS/cm)

Calcium, 

dissolved 

(mg/L)

Magnesium, 

dissolved 

(mg/L)

Potassium, 

dissolved 

(mg/L)

Sodium, 

dissolved 

(mg/L)

ANC 

(mg/L as 

CaCO3)

Chloride, 

dissolved 

(mg/L)

Fluoride, 

dissolved 

(mg/L)

Silica, 

dissolved 

(mg/L)

Sulfate, 

dissolved 

(mg/L)

Sulfide, 

total 

(mg/L)

Cycle 3 (Continued)

CHN-809 112 12/18/00 

13:28

9.2 1,600 2.6 3.5 12 330 291 280 1.5 19 75 ---

CHN-809 129 12/18/00 

15:27

9.0 1,960 3.3 4.1 12 400 324 360 1.7 22 88 ---

CHN-810 112 12/19/00 

12:45

8.8 2,260 3.6 3.9 14 460 341 430 2.9 22 110 ---

CHN-810 129 12/19/00 

14:55

8.6 3,530 7.2 8.8 20 750 453 740 5.1 27 160 ---

CHN-810 112 1/22/01 

12:38

8.7 2,400 4.2 4.7 16 500 352 470 5.7 23 120 ---

CHN-810 129 1/22/01 

15:27

8.7 3,620 7.9 9.5 21 760 461 780 5.0 28 170 ---

CHN-809 112 1/24/01 

12:49

9.2 1,220 1.2 1.3 7.8 260 271 170 3.3 18 68 ---

CHN-809 129 1/24/01 

15:00

8.9 1,900 2.9 3.4 11 400 322 340 3.6 22 89 ---

CHN-812 NA 1/31/01 

15:42

7.9 332 33 3.2 4.5 35 47 40 1.0 10 40 ---

CHN-812 NA 2/1/01 

10:15

8.3 685 27 3.3 12 100 93 120 1.0 17 53 ---

CHN-812 NA 2/1/01 

15:20

8.3 801 28 3.6 14 120 106 140 1.0 18 57 ---

CHN-812 NA 2/2/01 

10:06

8.4 1,160 29 4.6 18 190 146 230 1.1 21 68 ---

CHN-809 112 2/2/01 

12:20

8.6 3,470 5.8 11 21 720 408 800 3.5 28 140 ---

CHN-809 129 2/2/01 

14:50

8.7 3,090 3.8 7.4 18 640 389 640 1.8 27 130 ---

CHN-812 NA 2/2/01 

15:33

8.4 1,240 29 4.9 19 210 154 230 1.1 22 72 ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; ANC, acid neutralizing capacity; CaCO3, 

calcium carbonate; ---, data not available; E, estimated; TDW, treated drinking water; NA, not applicable; <, less than; μg/L, microgram per liter; M, presence verified, but not quantified]
60 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer Sample location (fig. 1; table 2) Sample depth, m bls Date/time (EST) Laboratory pH (su) Laboratory specific conduc- tance 

(μS/cm)

Calcium, 

dissolved 

(mg/L)

Magnesium, 

dissolved 

(mg/L)

Potassium, 

dissolved 

(mg/L)

Sodium, 

dissolved 

(mg/L)

ANC 

(mg/L as 

CaCO3)

Chloride, 

dissolved 

(mg/L)

Fluoride, 

dissolved 

(mg/L)

Silica, 

dissolved 

(mg/L)

Sulfate, 

dissolved 

(mg/L)

Sulfide, 

total 

(mg/L)

Cycle 3 (Continued)

CHN-812 NA 2/3/01 

10:33

7.8 1,660 28 6.0 21 290 191 320 1.4 24 87 ---

CHN-812 NA 2/3/01 

18:48

8.5 1,700 29 6.2 21 300 196 340 1.2 24 89 ---

CHN-812 NA 2/4/01 

12:00

8.3 1,960 26 7.1 22 360 221 410 1.2 26 97 ---

CHN-812 NA 2/4/01 

19:24

8.5 2,090 27 7.7 23 390 233 450 1.3 27 100 ---

CHN-812 NA 2/5/01 

10:37

8.2 2,340 26 8.4 24 450 257 510 1.4 28 110 ---

CHN-809 112 2/5/01 

13:00

8.6 4,240 7.3 12 24 890 487 960 3.3 32 170 ---

CHN-809 129 2/5/01 

14:49

8.5 4,080 6.3 11 23 860 483 910 3.4 32 170 ---

CHN-812 NA 2/5/01 

15:13

8.4 2,420 26 8.7 24 460 264 540 1.4 29 110 ---

CHN-812 NA 2/7/01 

11:00

8.6 3,250 26 11 27 620 337 710 1.5 33 140 ---

CHN-809 112 2/7/01 

12:58

8.4 5,030 10 16 30 1,100 558 1,200 1.5 35 200 ---

CHN-809 129 2/7/01 

15:06

8.4 4,890 9.2 14 27 1,000 554 1,100 1.5 35 200 ---

CHN-809 129 2/7/01 

15:07

8.4 4,890 9.1 14 25 1,100 554 1,100 1.5 35 200 ---

CHN-812 NA 2/13/01 

10:21

8.5 5,530 27 17 35 1,200 553 1,300 1.9 41 220 ---

CHN-809 112 2/13/01 

12:20

8.4 6,410 17 22 36 1,400 676 1,500 2.7 38 250 ---

CHN-809 129 2/13/01 

14:29

8.4 6,390 16 21 36 1,400 678 1,500 2.7 39 250 ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; ANC, acid neutralizing capacity; CaCO3, 

calcium carbonate; ---, data not available; E, estimated; TDW, treated drinking water; NA, not applicable; <, less than; μg/L, microgram per liter; M, presence verified, but not quantified]
Appendixes 61

Sample 

location

(fig. 1; 

table 2)

Sample 

depth, 

m bls 

Date/time 

(EST)

Laboratory 

pH 

(su)

Laboratory 

specific 

conductance 

(μS/cm)

Calcium, 

dissolved 

(mg/L)

Magnesium, 

dissolved 

(mg/L)

Potassium, 

dissolved 

(mg/L)

Sodium, 

dissolved 

(mg/L)

ANC 

(mg/L as 

CaCO3)

Chloride, 

dissolved 

(mg/L)

Fluoride, 

dissolved 

(mg/L)

Silica, 

dissolved 

(mg/L)

Sulfate, 

dissolved 

(mg/L)

Sulfide, 

total 

(mg/L)

Cycle 3 (Continued)

CHN-812 NA 2/20/01 

15:41

8.4 6,600 24 22 41 1,400 663 1,600 2.1 41 250 ---

CHN-812 NA 3/1/01 

14:07

8.4 6,970 23 25 39 1,500 715 1,700 2.2 41 260 ---

CHN-812 NA 3/5/01 

14:05

8.3 7,050 23 26 39 1,500 709 1,700 2.3 41 270 ---

CHN-812 NA 3/16/01 

15:12

8.2 7,180 23 27 40 1,600 725 1,700 2.3 41 270 ---

CHN-810 112 3/30/01 

12:16

8.2 7,410 23 27 36 1,600 738 1,800 2.3 41 280 ---

CHN-810 129 3/30/01 

14:38

8.2 7,210 21 25 41 1,600 739 1,800 2.4 41 280 ---

CHN-809 112 4/2/01 

12:37

8.7 7,320 21 26 41 1,600 747 1,800 2.3 40 280 ---

CHN-809 112 4/2/01 

12:38

8.6 7,310 21 25 42 1,600 735 1,800 2.3 39 280 ---

CHN-809 129 4/2/01 

13:56

8.6 7,240 21 25 40 1,600 748 1,800 2.3 40 280 ---

CHN-809 129 4/2/01 

13:57

8.4 7,250 21 25 41 1,600 747 1,800 2.3 40 280 ---

CHN-812 NA 4/2/01 

14:27

8.3 6,990 23 26 34 1,500 701 1,700 2.3 39 260 ---

Cycle 4

CHN-809 112 4/4/01 

11:16

8.2 7,190 21 26 40 1,600 --- 1,800 1.2 42 260 ---

CHN-809 129 4/4/01 

13:36

8.4 7,200 22 26 41 1,600 --- 1,800 1.2 42 260 ---

CHN-809 112 4/6/01 

11:50

8.2 6,470 17 21 36 1,400 --- 1,500 1.3 40 250 ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; ANC, acid neutralizing capacity; CaCO3, 

calcium carbonate; ---, data not available; E, estimated; TDW, treated drinking water; NA, not applicable; <, less than; μg/L, microgram per liter; M, presence verified, but not quantified]
62 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer Sample location (fig. 1; table 2) Sample depth, m bls Date/time (EST) Laboratory pH (su) Laboratory specific conduc- tance 

(μS/cm)

Calcium, 

dissolved 

(mg/L)

Magnesium, 

dissolved 

(mg/L)

Potassium, 

dissolved 

(mg/L)

Sodium, 

dissolved 

(mg/L)

ANC 

(mg/L as 

CaCO3)

Chloride, 

dissolved 

(mg/L)

Fluoride, 

dissolved 

(mg/L)

Silica, 

dissolved 

(mg/L)

Sulfate, 

dissolved 

(mg/L)

Sulfide, 

total 

(mg/L)

Cycle 4 (Continued)

CHN-809 129 4/6/01 

13:10

8.5 6,750 19 23 38 1,500 --- 1,600 1.3 40 250 ---

CHN-809 112 4/9/01 

11:42

8.5 4,510 8.8 10 25 980 --- 1,000 1.9 32 200 ---

CHN-809 129 4/9/01 

13:57

8.2 5,530 14 17 31 1,200 --- 1,300 1.6 37 220 ---

CHN-810 112 4/10/01 

11:36

8.1 7,070 21 25 39 1,600 --- 1,700 1.2 41 260 ---

CHN-810 129 4/10/01 

14:07

8.1 7,100 21 26 40 1,600 --- 1,700 1.2 42 260 ---

CHN811A Com- positea 4/11/01 13:10 8.1 7,530 23 28 43 1,700 --- 1,900 1.2 42 280 ---TDW NA 4/11/01 

14:27

7.8 436 24 3.0 3.5 55 --- 60 1.2 3.2 56 ---

CHN-809 112 4/12/01 

11:14

8.5 3,330 5.3 5.9 19 720 --- 680 2.5 28 150 ---

CHN-809 129 4/12/01 

13:36

8.3 4,680 11 12 26 1,000 --- 1,100 2.0 33 200 ---

CHN811A Com- positeb 4/13/01 8:39 8.1 7,420 22 27 41 1,700 --- 1,800 1.2 42 270 ---CHN-810 112 4/17/01 

11:29

8.3 5,520 14 16 32 1,200 --- 1,300 1.5 37 230 ---

CHN-810 129 4/17/01 

13:51

8.2 6,440 18 21 36 1,400 --- 1,500 1.4 40 250 ---

CHN-809 129 4/20/01 

13:50

8.5 3,310 6.4 7.4 19 700 --- 710 2.4 28 140 ---

CHN-810 112 4/23/01 

11:29

8.4 4,300 8.3 9.8 25 920 --- 930 2.1 31 190 ---

CHN-810 129 4/23/01 

14:28

8.5 5,750 15 18 32 1,300 --- 1,300 1.6 37 230 ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; ANC, acid neutralizing capacity; CaCO3, 

calcium carbonate; ---, data not available; E, estimated; TDW, treated drinking water; NA, not applicable; <, less than; μg/L, microgram per liter; M, presence verified, but not quantified]
Appendixes 63

Sample 

location

(fig. 1; 

table 2)

Sample 

depth, 

m bls 

Date/time 

(EST)

Laboratory 

pH 

(su)

Laboratory 

specific 

conductance 

(μS/cm)

Calcium, 

dissolved 

(mg/L)

Magnesium, 

dissolved 

(mg/L)

Potassium, 

dissolved 

(mg/L)

Sodium, 

dissolved 

(mg/L)

ANC 

(mg/L as 

CaCO3)

Chloride, 

dissolved 

(mg/L)

Fluoride, 

dissolved 

(mg/L)

Silica, 

dissolved 

(mg/L)

Sulfate, 

dissolved 

(mg/L)

Sulfide, 

total 

(mg/L)

Cycle 4 (Continued)

CHN-810 112 5/2/01 

11:45

8.6 3,140 5.1 5.8 20 670 423 630 2.8 27 150 <1.0

CHN-810 112 5/2/01 

11:46

8.4 3,130 5.4 5.6 18 650 423 640 5.6 26 150 <1.0

CHN-810 129 5/2/01 

14:17

8.2 4,930 12 15 28 1,100 569 1,100 2.0 34 200 <1.0

CHN-810 129 5/2/01 

14:18

8.0 4,940 12 13 27 1,100 569 1,100 4.1 33 200 <1.0

CHN-800 109 5/9/01 

11:22

7.5 10,000 44 62 65 2,100 732 2,600 2.0 41 370 3.2

CHN-810 112 5/18/01 

11:04

8.6 2,520 4.3 4.7 15 520 355 500 2.9 24 120 E1.0

CHN-810 129 5/18/01 

13:16

8.2 4,200 10 12 24 860 497 940 2.3 30 180 E1.0

CHN811A Com- positeb 5/22/01 12:26 7.9 7,520 23 29 42 1,600 746 1,800 1.2 41 290 <1.0CHN-809 112 5/23/01 

11:40

9.6 1,350 2.1 2.4 7.7 280 264 210 2.6 17 63 E1.0

CHN-809 112 5/23/01 

11:41

9.6 1,340 2.1 2.4 7.8 280 265 210 2.6 17 59 E1.0

TDW NA 5/23/01 

13:25

8.3 220 19 2.1 2.0 18 31 20 1.0 3.9 31 E1.0

CHN-809 129 5/23/01 

13:50

9.2 2,040 3.8 4.4 12 420 326 370 1.7 22 91 E1.0

CHN-809 112 5/31/01 

12:43

9.6 1,230 1.8 2.2 7.6 270 257 190 2.6 17 60 E1.0

CHN-809 129 5/31/01 

15:08

9.4 1,610 2.5 2.7 9.6 350 295 270 3.3 20 76 E1.0

CHN-810 112 6/5/01 

11:20

8.8 2,190 3.0 3.4 13 480 330 410 5.7 22 110 E1.0

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; ANC, acid neutralizing capacity; CaCO3, 

calcium carbonate; ---, data not available; E, estimated; TDW, treated drinking water; NA, not applicable; <, less than; μg/L, microgram per liter; M, presence verified, but not quantified]
64 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer Sample location (fig. 1; table 2) Sample depth, m bls Date/time (EST) Laboratory pH (su) Laboratory specific conduc- tance 

(μS/cm)

Calcium, 

dissolved 

(mg/L)

Magnesium, 

dissolved 

(mg/L)

Potassium, 

dissolved 

(mg/L)

Sodium, 

dissolved 

(mg/L)

ANC 

(mg/L as 

CaCO3)

Chloride, 

dissolved 

(mg/L)

Fluoride, 

dissolved 

(mg/L)

Silica, 

dissolved 

(mg/L)

Sulfate, 

dissolved 

(mg/L)

Sulfide, 

total 

(mg/L)

Cycle 4 (Continued)

CHN-810 129 6/5/01 

13:55

8.2 3,600 7.1 8.5 21 760 451 750 4.9 28 160 E1.0

CHN-809 112 6/26/01 

11:56

9.4 1,480 2.4 2.9 8.8 300 274 230 3.0 18 66 <1.0

CHN-809 129 6/26/01 

14:15

9.2 1,860 3.2 4.0 11 390 307 340 3.3 22 79 <1.0

CHN-810 112 6/27/01 

12:29

8.8 2,130 2.9 3.1 13 440 326 380 5.9 22 100 <1.0

CHN-810 129 6/27/01 

14:30

8.2 3,630 7.3 8.8 20 775 453 750 5.0 28 160 <1.0

CHN-809 112 7/17/01 

10:55

--- --- --- --- --- --- --- --- 3.0 --- --- ---

CHN-809 129 7/17/01 

13:09

9.1 1,920 3.2 4.1 12 414 313 350 3.3 21 82 <1.0

CHN-810 112 7/19/01 

11:40

8.7 2,230 3.2 3.6 14 477 333 410 5.7 22 110 <1.0

CHN-810 129 7/19/01 

13:46

8.2 3,650 7.4 9.1 21 795 458 770 4.9 28 160 <1.0

CHN-809 112 8/7/01 

12:24

9.3 1,460 2.1 2.5 8.6 296 276 210 3.0 17 66 <1.0

CHN-809 129 8/7/01 

14:56

9.2 1,790 2.8 3.4 11 388 309 320 3.5 21 82 <1.0

CHN-810 112 8/8/01 

12:22

8.7 2,210 3.2 3.4 13 465 332 400 5.9 22 110 <1.0

CHN-810 129 8/8/01 

14:40

8.2 3,610 7.7 9.3 20 782 454 760 5.1 28 160 <1.0

CHN-809 112 8/22/01 

12:10

9.3 1,430 2.2 2.9 10 310 275 230 3.0 17 66 <1.0

CHN-809 129 8/22/01 

14:40

9.1 1,830 2.8 3.6 12 380 311 330 3.5 21 81 <1.0

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; ANC, acid neutralizing capacity; CaCO3, 

calcium carbonate; ---, data not available; E, estimated; TDW, treated drinking water; NA, not applicable; <, less than; μg/L, microgram per liter; M, presence verified, but not quantified]
Appendixes 65

Sample 

location

(fig. 1; 

table 2)

Sample 

depth, 

m bls 

Date/time 

(EST)

Laboratory 

pH 

(su)

Laboratory 

specific 

conductance 

(μS/cm)

Calcium, 

dissolved 

(mg/L)

Magnesium, 

dissolved 

(mg/L)

Potassium, 

dissolved 

(mg/L)

Sodium, 

dissolved 

(mg/L)

ANC 

(mg/L as 

CaCO3)

Chloride, 

dissolved 

(mg/L)

Fluoride, 

dissolved 

(mg/L)

Silica, 

dissolved 

(mg/L)

Sulfate, 

dissolved 

(mg/L)

Sulfide, 

total 

(mg/L)

Cycle 4 (Continued)

CHN-810 129 8/23/01 

14:40

8.3 3,600 7.5 9.8 24 750 456 800 5.0 28 160 <1.0

CHN-809 112 9/18/01 

12:02

9.3 1,440 2.0 2.5 8.6 310 276 230 3.1 17 66 <1.0

CHN-809 129 9/18/01 

14:43

9.1 1,890 2.9 3.7 11 400 316 340 3.4 21 83 <1.0

CHN-810 112 9/19/01 

11:46

8.8 2,280 3.4 3.9 13 470 336 420 5.7 22 110 <1.0

CHN-810 129 9/19/01 

14:08

8.2 3,630 7.3 9.3 19 780 457 800 5.1 27 160 <1.0

CHN-809 112 10/15/01 

11:52

9.2 1,580 2.6 3.6 9.9 336 E313 276 3.0 18 72 <1.0

CHN-809 129 10/15/01 

14:12

9.0 1,960 3.1 4.1 11 406 E339 360 3.4 21 85 <1.0

CHN-810 112 10/16/01 

12:18

8.6 2,360 3.8 4.5 14 490 344 440 5.6 22 110 <1.0

CHN-810 129 10/16/01 

14:17

8.4 3,740 7.8 10 20 800 465 770 4.8 28 160 <1.0

CHN-812 NA 11/8/01 

14:40

7.9 401 21 2.8 7.6 49 E70 48 1.0 13 42 <1.0

CHN-812 NA 11/9/01 

8:40

8.1 823 27 4.1 15 130 E112 150 1.0 18 53 <1.0

CHN-810 112 11/9/01 

13:00

8.2 4,960 13 18 33 1,030 E552 1,150 4.0 32 200 <1.0

CHN-810 129 11/9/01 

15:20

8.2 4,550 11 15 28 966 E534 1,050 4.2 33 189 <1.0

CHN-812 NA 11/9/01 

16:10

8.1 986 27 4.8 17 160 E130 190 1.1 19 58 <1.0

CHN-812 NA 11/10/01 

10:20

8.1 1,380 26 6.0 21 236 E174 289 1.2 22 72 <1.0

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; ANC, acid neutralizing capacity; CaCO3, 

calcium carbonate; ---, data not available; E, estimated; TDW, treated drinking water; NA, not applicable; <, less than; μg/L, microgram per liter; M, presence verified, but not quantified]
66 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer Sample location (fig. 1; table 2) Sample depth, m bls Date/time (EST) Laboratory pH (su) Laboratory specific conduc- tance 

(μS/cm)

Calcium, 

dissolved 

(mg/L)

Magnesium, 

dissolved 

(mg/L)

Potassium, 

dissolved 

(mg/L)

Sodium, 

dissolved 

(mg/L)

ANC 

(mg/L as 

CaCO3)

Chloride, 

dissolved 

(mg/L)

Fluoride, 

dissolved 

(mg/L)

Silica, 

dissolved 

(mg/L)

Sulfate, 

dissolved 

(mg/L)

Sulfide, 

total 

(mg/L)

Cycle 4 (Continued)

CHN-812 NA 11/10/01 

16:17

8.2 1,290 26 5.7 20 216 E165 256 1.1 21 70 <1.0

CHN-812 NA 11/11/01 

12:20

8.2 1,700 25 7.1 22 310 E204 365 1.3 23 83 <1.0

CHN-809 112 11/13/01 

13:50

8.3 4,460 8.8 15 28 968 E504 1,050 3.1 34 174 <1.0

CHN-809 129 11/13/01 

16:20

8.5 4,260 6.5 13 26 924 E521 957 3.1 33 172 <1.0

CHN-812 NA 11/13/01 

17:21

8.2 2,560 24 10 25 510 E286 581 1.4 29 115 <1.0

CHN-812 NA 11/27/01 

16:30

8.0 3,540 35 15 23 690 E346 790 1.3 31 140 <1.0

CHN-812 NA 12/6/01 

12:30

8.1 6,260 24 21 39 1,270 E641 1,570 1.9 42 232 <1.0

CHN-809 112 12/18/01 

12:14

8.1 6,890 20 28 40 1,430 709 1,680 2.4 41 250 <1.0

CHN-812 NA 12/18/01 

13:27

8.2 6,470 27 25 36 1,330 650 1,560 1.9 43 240 <1.0

CHN-809 129 12/18/01 

14:39

8.1 6,710 18 26 39 1,400 713 1,600 2.4 41 250 <1.0

CHN-809 112 2/14/02 

13:46

7.8 7,250 21 29 41 1,570 756 1,800 2.2 41 270 <1.0

CHN-809 129 2/14/02 

15:48

7.7 7,110 20 27 39 1,530 754 1,740 2.3 41 260 <1.0

CHN-810 112 2/15/02 

12:55

7.8 7,090 19 27 41 1,490 750 1,720 2.3 41 270 <1.0

CHN-810 129 2/15/02 

15:24

7.8 7,380 23 30 45 1,560 755 1,840 2.2 42 270 2.0

CHN-812 NA 2/15/02 

16:06

7.8 7,120 21 29 42 1,510 747 1,740 2.3 41 270 1.0

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; ANC, acid neutralizing capacity; CaCO3, 

calcium carbonate; ---, data not available; E, estimated; TDW, treated drinking water; NA, not applicable; <, less than; μg/L, microgram per liter; M, presence verified, but not quantified]
Appendixes 67

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in 

Charleston, South Carolina.—Continued

[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; μg/L, microgram per liter; ANC, acid neutralizing capacity; CaCO3, calcium carbonate; ---, data not available; NA, not applicable; E, estimated; TDW, treated drinking water; <, less than; M, presence verified, but not quantified]

Sample 

location

(fig. 1; 

table 2)

Sample 

depth, 

m bls 

Date/time 

(EST)

Nitrogen 

ammonia 

(mg/L)

Nitrate + 

nitrate, 

dissolved 

(mg/L)

Nitrogen, 

nitrite 

(mg/L)

Boron, 

dissolved 

(μg/L)

Iron, 

dissolved 

(μg/L)

Manganese, 

dissolved 

(μg/L)

Strontium, 

dissolved 

(μg/L)

Water 

temperature 

(o C)

Field pH 

(su)

Field 

specific 

conductance 

(μS/cm)

Field 

dissolved 

oxygen, 

mg/L

Field 

iron, 

mg/L

Field 

sulfide, 

mg/L

Field 

chloride, 

mg/L

Cycle 1

CHN-809 129 11/8/99 

14:18

--- --- --- 3,570 --- --- 1,160 23.9 7.5 6,840 <1.0 --- --- ---

CHN-809 129 12/3/99 

13:49

--- --- --- 2,230 --- --- 530 21.5 7.9 3,960 <1.0 --- --- ---

CHN-809 116 12/3/99 

16:33

--- --- --- 1,850 --- --- 350 19.2 8.3 3,120 <1.0 --- --- ---

CHN-810 129 12/7/99 

13:20

--- --- --- 3,420 --- --- 1,030 17.5 7.6 6,180 <1.0 --- --- ---

CHN-810 112 12/7/99 

15:47

--- --- --- 2,710 --- --- 670 17.5 7.9 4,810 <1.0 --- --- ---

CHN-810 129 1/6/00 

14:01

--- --- --- 2,590 --- --- 690 19.8 8.0 4,610 <1.0 --- --- ---

CHN-810 112 1/6/00 

16:20

--- --- --- 1,590 --- --- 270 --- --- --- --- --- --- ---

CHN-809 129 1/12/00 

14:32

--- --- --- 1,520 --- --- 360 22.3 9.0 2,840 <1.0 --- --- ---

CHN-809 116 1/12/00 

16:34

--- --- --- 1,080 --- --- 220 19.7 9.4 2,030 <1.0 --- --- ---

TDW NA 1/12/00 

16:34

--- --- --- 17 --- --- 39 --- --- --- --- --- --- ---

CHN-809 116 2/7/00 

14:15

--- --- --- 1,120 --- --- 220 21.6 9.2 2,110 <1.0 --- --- ---

CHN-809 129 2/7/00 

16:35

--- --- --- 1,270 --- --- 270 19.5 9.1 2,380 <1.0 --- --- ---

CHN-812 NA 3/7/00 

12:50

--- --- --- 3,970 --- --- 1,240 23.6 7.8 7,040 --- --- --- ---

CHN-809 129 4/6/00 

12:36

--- --- --- 4,410 --- --- 1,430 23.6 7.9 7,380 <1.0 --- --- ---
68 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer Sample location (fig. 1; table 2) Sample depth, m bls Date/time (EST) Nitrogen ammonia (mg/L) Nitrate + nitrate, dissolved (mg/L) Nitrogen, nitrite (mg/L) Boron, dissolved 

(μg/L)

Iron, 

dissolved 

(μg/L)

Manganese, 

dissolved 

(μg/L)

Strontium, 

dissolved 

(μg/L)

Water 

temperature 

(

o C)

Field pH 

(su)

Field 

specific 

conductance 

(μS/cm)

Field 

dissolved 

oxygen, 

mg/L

Field 

iron, 

mg/L

Field 

sulfide, 

mg/L

Field 

chloride, 

mg/L

Cycle 2

CHN-809 116 5/15/00 

10:53

--- --- --- 3,050 --- --- 770 24.7 7.7 5,280 <1.0 --- --- ---

CHN-809 129 5/15/00 

12:36

--- --- --- 3,180 --- --- 840 24.4 7.6 5,390 <1.0 --- --- ---

TDW NA 5/19/00 

12:49

--- --- --- 23 --- --- 42 --- --- --- --- --- --- ---

CHN-809 116 5/23/00 

11:04

--- --- --- 1,870 --- --- 320 26.6 8.5 3,070 <1.0 --- --- ---

CHN-809 129 5/23/00 

13:09

--- --- --- 2,140 --- --- 440 26.7 8.3 3,730 <1.0 --- --- ---

CHN-810 112 5/26/00 

10:57

--- --- --- 2,710 --- --- 560 --- --- --- --- --- --- ---

CHN-810 129 5/26/00 

13:02

--- --- --- 3,380 --- --- 940 --- --- --- --- --- --- ---

CHN-810 112 6/15/00 

11:32

--- --- --- 1,640 --- --- 210 30.2 8.9 2,540 <1.0 --- --- ---

CHN-810 129 6/15/00 

14:31

--- --- --- 2,540 --- --- 600 28.5 8.2 4,420 <1.0 --- --- ---

CHN-809 112 6/16/00 

11:39

--- --- --- --- --- --- --- 30.2 9.8 1,380 <1.0 --- --- ---

CHN-809 129 6/16/00 

13:35

--- --- --- 1,350 --- --- 270 28.6 9.3 2,540 <1.0 --- --- ---

CHN-809 112 7/17/00 

11:04

--- --- --- 782 --- --- 130 27.7 9.8 1,520 <1.5 --- --- ---

CHN-809 129 7/17/00 

12:52

--- --- --- 1,020 --- --- 160 27.1 9.5 1,960 <1.0 --- --- ---

CHN-810 112 7/18/00 

10:34

--- --- --- 1,510 --- --- 220 25.3 8.9 --- <1.0 --- --- ---

CHN-810 129 7/18/00 

12:34

--- --- --- 2,260 --- --- 480 26.8 8.3 --- <1.0 --- --- ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; μg/L, microgram per liter; ANC, acid neutralizing capacity; CaCO3, calcium carbonate; ---, data not available; NA, not applicable; E, estimated; TDW, treated drinking water; <, less than; M, presence verified, but not quantified]
Appendixes 69

Sample 

location

(fig. 1; 

table 2)

Sample 

depth, 

m bls 

Date/time 

(EST)

Nitrogen 

ammonia 

(mg/L)

Nitrate + 

nitrate, 

dissolved 

(mg/L)

Nitrogen, 

nitrite 

(mg/L)

Boron, 

dissolved 

(μg/L)

Iron, 

dissolved 

(μg/L)

Manganese, 

dissolved 

(μg/L)

Strontium, 

dissolved 

(μg/L)

Water 

temperature 

(o C)

Field pH 

(su)

Field 

specific 

conductance 

(μS/cm)

Field 

dissolved 

oxygen, 

mg/L

Field 

iron, 

mg/L

Field 

sulfide, 

mg/L

Field 

chloride, 

mg/L

Cycle 2 (Continued)

CHN-812 NA 8/2/00 

13:30

--- --- --- 3,410 --- --- 880 --- --- --- --- --- --- ---

CHN-809 112 8/31/00 

11:48

--- --- --- 4,360 --- --- 1,500 24.8 8.3 --- <1.0 --- --- ---

CHN-809 129 8/31/00 

13:42

--- --- --- 4,360 --- --- 1,420 25.5 8.3 --- <1.0 --- --- ---

CHN-810 112 9/6/00 

10:22

--- --- --- 4,620 --- --- 1,630 23.6 8.4 --- <1.0 --- --- ---

CHN-810 129 9/6/00 

12:04

--- --- --- 4,590 --- --- 1,520 22.1 8.4 --- <1.0 --- --- ---

Cycle 3

CHN-812 NA 9/11/00 

13:52

--- --- --- 4,170 --- --- 1,450 26.7 7.8 --- --- --- --- ---

CHN-809 112 9/12/00 

10:40

--- --- --- 4,310 21 <1 1,400 26.9 7.9 --- <1.0 --- --- ---

CHN-809 129 9/12/00 

12:34

--- --- --- 4,210 27 1 1,400 26.3 8.1 --- <1.0 --- --- ---

CHN-810 112 9/14/00 

11:05

--- --- --- 4,410 271 6 1,400 25.6 8.3 --- <1.0 --- --- ---

CHN-810 129 9/14/00 

12:57

--- --- --- 4,270 17 <1 1,400 25.7 8.3 --- <1.0 --- --- ---

CHN-809 112 9/15/00 

12:11

--- --- --- 3,910 186 4 1,100 28.1 7.9 --- <1.0 --- --- ---

CHN-809 129 9/15/00 

14:18

--- --- --- 3,830 20 <1 1,200 26.8 7.8 --- <1.0 --- --- ---

CHN-809 112 9/19/00 

10:44

--- --- --- 2,270 194 3 390 25.6 9.2 --- <1.0 --- --- ---

CHN-809 129 9/19/00 

12:40

--- --- --- 2,890 22 <1 720 25.6 9.0 --- <1.0 --- --- ---

CHN-810 112 9/20/00 

10:54

--- --- --- 3,970 311 6 1,300 25.2 7.8 --- <1.0 --- --- ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; μg/L, microgram per liter; ANC, acid neutralizing capacity; CaCO3, calcium carbonate; ---, data not available; NA, not applicable; E, estimated; TDW, treated drinking water; <, less than; M, presence verified, but not quantified]
70 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer Sample location (fig. 1; table 2) Sample depth, m bls Date/time (EST) Nitrogen ammonia (mg/L) Nitrate + nitrate, dissolved (mg/L) Nitrogen, nitrite (mg/L) Boron, dissolved 

(μg/L)

Iron, 

dissolved 

(μg/L)

Manganese, 

dissolved 

(μg/L)

Strontium, 

dissolved 

(μg/L)

Water 

temperature 

(

o C)

Field pH 

(su)

Field 

specific 

conductance 

(μS/cm)

Field 

dissolved 

oxygen, 

mg/L

Field 

iron, 

mg/L

Field 

sulfide, 

mg/L

Field 

chloride, 

mg/L

Cycle 3 (Continued)

CHN-810 129 9/20/00 

12:45

--- --- --- 4,170 363 13 1,300 23.8 7.8 --- <1.0 --- --- ---

CHN-809 112 9/22/00 

11:45

--- --- --- 1,790 342 15 220 27.2 8.8 --- <1.0 --- --- ---

CHN-809 129 9/22/00 

13:33

--- --- --- 2,480 15 <1 500 --- --- --- --- --- --- ---

CHN-810 112 9/26/00 

9:55

--- --- --- 3,140 66 2 740 21.8 8.2 --- <1.0 --- --- ---

CHN-810 129 9/26/00 

11:39

--- --- --- 3,590 18 1 1,100 23.3 8.0 --- <1.0 --- --- ---

CHN-809 112 10/2/00 

10:53

--- --- --- 1,120 16 <1 87 24.4 9.9 --- <1.0 --- --- ---

CHN-809 129 10/2/00 

12:55

--- --- --- 1,760 12 <1 310 25.0 9.8 --- <1.0 --- --- ---

CHN-810 112 10/3/00 

10:35

--- --- --- 2,330 23 1 380 22.9 9.5 --- <1.0 --- --- ---

CHN-810 129 10/3/00 

12:30

--- --- --- 3,090 20 1 810 25.7 9.1 --- <1.0 --- --- ---

CHN-810 112 10/13/00 

10:40

--- --- --- 1,780 66 3 230 21.3 10.5 --- <1.0 --- --- ---

CHN-810 129 10/13/00 

12:51

--- --- --- 2,610 8 1 610 24.2 9.8 --- <1.0 --- --- ---

CHN-809 112 10/23/00 

11:24

--- --- --- 670 16 <1 81 24.2 10.3 1,130 <1.0 --- --- ---

CHN-809 129 10/23/00 

13:34

--- --- --- 1,050 6 <1 190 24.8 10.0 1,800 <1.0 --- --- ---

CHN-810 112 10/24/00 

10:54

--- --- --- 1,530 9 <1 210 22.1 9.0 2,150 <1.0 --- --- ---

CHN-810 129 10/24/00 

13:12

--- --- --- 2,400 8 <1 560 23.7 8.3 3,580 <1.0 --- --- ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; μg/L, microgram per liter; ANC, acid neutralizing capacity; CaCO3, calcium carbonate; ---, data not available; NA, not applicable; E, estimated; TDW, treated drinking water; <, less than; M, presence verified, but not quantified]
Appendixes 71

Sample 

location

(fig. 1; 

table 2)

Sample 

depth, 

m bls 

Date/time 

(EST)

Nitrogen 

ammonia 

(mg/L)

Nitrate + 

nitrate, 

dissolved 

(mg/L)

Nitrogen, 

nitrite 

(mg/L)

Boron, 

dissolved 

(μg/L)

Iron, 

dissolved 

(μg/L)

Manganese, 

dissolved 

(μg/L)

Strontium, 

dissolved 

(μg/L)

Water 

temperature 

(o C)

Field pH 

(su)

Field 

specific 

conductance 

(μS/cm)

Field 

dissolved 

oxygen, 

mg/L

Field 

iron, 

mg/L

Field 

sulfide, 

mg/L

Field 

chloride, 

mg/L

Cycle 3 (Continued)

CHN-809 112 11/2/00 

11:56

--- --- --- 750 6 <1 120 24.2 9.6 1,240 <1.0 --- --- ---

CHN-809 129 11/2/00 

14:30

--- --- --- 940 <2 <1 150 24.0 9.4 1,630 <1.0 --- --- ---

TDW NA 11/2/00 

14:40

--- --- --- 37 44 12 44 --- --- --- --- --- --- ---

CHN-810 112 11/3/00 

11:25

--- --- --- 1,430 6 <1 150 23.9 9.0 1,940 <1.0 --- --- ---

CHN-810 112 11/3/00 

11:26

--- --- --- 1,420 9 <1 160 23.9 9.0 1,940 <1.0 --- --- ---

CHN-810 129 11/3/00 

13:27

--- --- --- 2,150 4 <1 420 23.6 8.4 3,120 <1.0 --- --- ---

CHN-810 129 11/3/00 

13:28

--- --- --- 2,090 <2 <1 430 23.6 8.4 3,120 <1.0 --- --- ---

CHN-809 112 11/13/00 

12:50

--- --- --- 940 7 <1 140 23.2 9.5 1,810 <1.0 --- --- ---

CHN-809 129 11/13/00 

14:56

--- --- --- 1,040 6 <1 170 22.5 9.3 2,090 <1.0 --- --- ---

CHN-810 112 11/20/00 

12:35

--- --- --- 1,480 10 <1 170 19.3 9.4 1,910 <1.0 --- --- ---

CHN-810 129 11/20/00 

14:28

--- --- --- 2,120 3 45 410 19.6 9.0 2,980 <1.0 --- --- ---

CHN-809 112 12/5/00 

12:07

--- --- --- 810 6 <1 150 17.8 9.5 1,290 <1.0 --- --- ---

CHN-809 129 12/5/00 

14:20

--- --- --- 1,060 5 <1 180 20.3 9.4 1,630 <1.0 --- --- ---

CHN-809 129 12/5/00 

14:21

--- --- --- 1,060 3 <1 180 --- --- --- --- --- --- ---

CHN-810 129 12/6/00 

14:43

--- --- --- 2,200 10 1 450 19.7 8.1 2,820 <1.0 --- --- ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; μg/L, microgram per liter; ANC, acid neutralizing capacity; CaCO3, calcium carbonate; ---, data not available; NA, not applicable; E, estimated; TDW, treated drinking water; <, less than; M, presence verified, but not quantified]
72 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer Sample location (fig. 1; table 2) Sample depth, m bls Date/time (EST) Nitrogen ammonia (mg/L) Nitrate + nitrate, dissolved (mg/L) Nitrogen, nitrite (mg/L) Boron, dissolved 

(μg/L)

Iron, 

dissolved 

(μg/L)

Manganese, 

dissolved 

(μg/L)

Strontium, 

dissolved 

(μg/L)

Water 

temperature 

(

o C)

Field pH 

(su)

Field 

specific 

conductance 

(μS/cm)

Field 

dissolved 

oxygen, 

mg/L

Field 

iron, 

mg/L

Field 

sulfide, 

mg/L

Field 

chloride, 

mg/L

Cycle 3 (Continued)

CHN-809 112 12/18/00 

13:28

--- --- --- 970 6 <1 150 17.5 10.3 1,610 <1.5 --- --- ---

CHN-809 129 12/18/00 

15:27

--- --- --- 1,060 7 <1 190 23.9 8.8 1,640 <1.0 --- --- ---

CHN-810 112 12/19/00 

12:45

--- --- --- 1,500 20 2 220 16.1 8.8 2,290 <1.0 --- --- ---

CHN-810 129 12/19/00 

14:55

--- --- --- 2,180 9 <1 450 16.2 8.3 3,590 <1.5 --- --- ---

CHN-810 112 1/22/01 

12:38

--- --- --- 1,520 32 <1 230 13.8 9.5 2,440 <1.0 --- --- ---

CHN-810 129 1/22/01 

15:27

--- --- --- 2,230 18 <1 480 15.7 10.4 3,670 <1.0 --- --- ---

CHN-809 112 1/24/01 

12:49

--- --- --- 670 10 <1 61 19.0 9.7 1,220 <1.0 --- --- ---

CHN-809 129 1/24/01 

15:00

--- --- --- 1,020 3 <1 150 20.4 9.3 1,870 <1.0 --- --- ---

CHN-812 NA 1/31/01 

15:42

--- --- --- 97 718 31 100 --- --- --- --- --- --- ---

CHN-812 NA 2/1/01 

10:15

--- --- --- 210 42 16 130 21.9 8.1 697 <2.5 --- --- ---

CHN-812 NA 2/1/01 

15:20

--- --- --- 250 16 15 150 22.2 8.0 808 <3.0 --- --- ---

CHN-812 NA 2/2/01 

10:06

--- --- --- 420 9 14 190

CHN-809 112 2/2/01 

12:20

--- --- --- 1,890 27 <1 440 21.9 7.7 1,180 <2.5 --- --- ---

CHN-809 129 2/2/01 

14:50

--- --- --- 1,790 17 <1 320 17.8 --- 3,140 --- --- --- ---

CHN-812 NA 2/2/01 

15:33

--- --- --- 460 9 14 200 --- --- --- --- --- --- ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; μg/L, microgram per liter; ANC, acid neutralizing capacity; CaCO3, calcium carbonate; ---, data not available; NA, not applicable; E, estimated; TDW, treated drinking water; <, less than; M, presence verified, but not quantified]
Appendixes 73

Sample 

location

(fig. 1; 

table 2)

Sample 

depth, 

m bls 

Date/time 

(EST)

Nitrogen 

ammonia 

(mg/L)

Nitrate + 

nitrate, 

dissolved 

(mg/L)

Nitrogen, 

nitrite 

(mg/L)

Boron, 

dissolved 

(μg/L)

Iron, 

dissolved 

(μg/L)

Manganese, 

dissolved 

(μg/L)

Strontium, 

dissolved 

(μg/L)

Water 

temperature 

(o C)

Field pH 

(su)

Field 

specific 

conductance 

(μS/cm)

Field 

dissolved 

oxygen, 

mg/L

Field 

iron, 

mg/L

Field 

sulfide, 

mg/L

Field 

chloride, 

mg/L

Cycle 3 (Continued)

CHN-812 NA 2/3/01 

10:33

--- --- --- 700 8 12 240 --- --- --- --- --- --- ---

CHN-812 NA 2/3/01 

18:48

--- --- --- 710 111 12 250 --- --- --- --- --- --- ---

CHN-812 NA 2/4/01 

12:00

--- --- --- 860 7 9 260 --- --- --- --- --- --- ---

CHN-812 NA 2/4/01 

19:24

--- --- --- 950 46 10 290 --- --- --- --- --- --- ---

CHN-812 NA 2/5/01 

10:37

--- --- --- 1,100 18 9 310 23.6 --- 2,430 --- --- --- ---

CHN-809 112 2/5/01 

13:00

--- --- --- 2,430 19 <1 560 21.3 8.0 4,320 <1.0 --- --- ---

CHN-809 129 2/5/01 

14:49

--- --- --- 2,420 28 <1 500 21.8 8.0 4,130 <1.0 --- --- ---

CHN-812 NA 2/5/01 

15:13

--- --- --- 1,180 19 9 320 --- --- --- --- --- --- ---

CHN-812 NA 2/7/01 

11:00

--- --- --- 1,670 52 8 410 23.5 7.3 3,270 <2.0 --- --- ---

CHN-809 112 2/7/01 

12:58

--- --- --- 3,040 35 <1 750 23.2 7.9 5,040 <1.0 --- --- ---

CHN-809 129 2/7/01 

15:06

--- --- --- 2,840 <2 <1 700 22.7 7.9 4,880 <1.0 --- --- ---

CHN-809 129 2/7/01 

15:07

--- --- --- 2,850 16 <1 700 22.7 7.9 4,880 <1.0 --- --- ---

CHN-812 NA 2/13/01 

10:21

--- --- --- 3,080 9 6 770 19.8 7.4 5,640 <2.0 --- --- ---

CHN-809 112 2/13/01 

12:20

--- --- --- 3,770 30 <1 1,100 16.8 6.9 6,320 <1.0 --- --- ---

CHN-809 129 2/13/01 

14:29

--- --- --- 3,780 <2 <1 1,100 20.6 6.9 6,290 <1.0 --- --- ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; μg/L, microgram per liter; ANC, acid neutralizing capacity; CaCO3, calcium carbonate; ---, data not available; NA, not applicable; E, estimated; TDW, treated drinking water; <, less than; M, presence verified, but not quantified]
74 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer Sample location (fig. 1; table 2) Sample depth, m bls Date/time (EST) Nitrogen ammonia (mg/L) Nitrate + nitrate, dissolved (mg/L) Nitrogen, nitrite (mg/L) Boron, dissolved 

(μg/L)

Iron, 

dissolved 

(μg/L)

Manganese, 

dissolved 

(μg/L)

Strontium, 

dissolved 

(μg/L)

Water 

temperature 

(

o C)

Field pH 

(su)

Field 

specific 

conductance 

(μS/cm)

Field 

dissolved 

oxygen, 

mg/L

Field 

iron, 

mg/L

Field 

sulfide, 

mg/L

Field 

chloride, 

mg/L

Cycle 3 (Continued)

CHN-812 NA 2/20/01 

15:41

--- --- --- 3,940 5 4 1,100 23.3 7.1 6,520 <2.0 --- --- ---

CHN-812 NA 3/1/01 

14:07

--- --- --- 4,020 <2 2 1,300 25.0 7.6 6,990 <2.0 --- --- ---

CHN-812 NA 3/5/01 

14:05

--- --- --- 3,980 <2 3 1,300 23.0 7.4 7,230 <2.5 --- --- ---

CHN-812 NA 3/16/01 

15:12

--- --- --- 4,390 <2 1 1,400 26.0 7.5 7,260 <2.5 --- --- ---

CHN-810 112 3/30/01 

12:16

--- --- --- 4,270 15 1 1,500 22.0 7.0 7,420 <1.0 0.1 0.15 ---

CHN-810 129 3/30/01 

14:38

--- --- --- 4,110 <2 <1 1,400 23.6 7.0 7,180 <1.0 0.1 0.1 ---

CHN-809 112 4/2/01 

12:37

--- --- --- 4,260 <2 <1 1,400 22.6 7.0 7,310 <1.0 0.1 <0.05 ---

CHN-809 112 4/2/01 

12:38

--- --- --- 4,270 6 <1 1,400 --- --- --- --- --- --- ---

CHN-809 129 4/2/01 

13:56

--- --- --- 4,390 <2 <1 1,400 22.4 7.0 7,220 <1.0 0.1 <0.05 ---

CHN-809 129 4/2/01 

13:57

--- --- --- 4,270 <2 <1 1,400 --- --- --- --- --- --- ---

CHN-812 NA 4/2/01 

14:27

--- --- --- 3,900 <2 2 1,400 25.0 7.4 7,170 <1.0 0.2 <0.05 ---

Cycle 4

CHN-809 112 4/4/01 

11:16

--- --- --- 4,230 12 <1 1,400 23.3 7.5 7,130 <1.0 0.2 <0.05 ---

CHN-809 129 4/4/01 

13:36

--- --- --- 4,260 9 <1 1,400 23.4 7.5 7,220 <1.0 0.1 <0.05 ---

CHN-809 112 4/6/01 

11:50

--- --- --- 3,800 11 <1 1,200 24.7 7.8 6,470 <1.0 0.15 <0.05 ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; μg/L, microgram per liter; ANC, acid neutralizing capacity; CaCO3, calcium carbonate; ---, data not available; NA, not applicable; E, estimated; TDW, treated drinking water; <, less than; M, presence verified, but not quantified]
Appendixes 75

Sample 

location

(fig. 1; 

table 2)

Sample 

depth, 

m bls 

Date/time 

(EST)

Nitrogen 

ammonia 

(mg/L)

Nitrate + 

nitrate, 

dissolved 

(mg/L)

Nitrogen, 

nitrite 

(mg/L)

Boron, 

dissolved 

(μg/L)

Iron, 

dissolved 

(μg/L)

Manganese, 

dissolved 

(μg/L)

Strontium, 

dissolved 

(μg/L)

Water 

temperature 

(o C)

Field pH 

(su)

Field 

specific 

conductance 

(μS/cm)

Field 

dissolved 

oxygen, 

mg/L

Field 

iron, 

mg/L

Field 

sulfide, 

mg/L

Field 

chloride, 

mg/L

Cycle 4 (Continued)

CHN-809 129 4/6/01 

13:10

--- --- --- 3,910 9 1 1,200 24.5 7.7 6,880 <1.0 0.1 <0.05 ---

CHN-809 112 4/9/01 

11:42

--- --- --- 2,680 9 <1 570 26.9 8.0 4,550 <1.0 0.1 <0.05 ---

CHN-809 129 4/9/01 

13:57

--- --- --- 3,220 7 <1 890 27.7 7.7 5,610 <1.0 0.1 <0.05 ---

CHN-810 112 4/10/01 

11:36

--- --- --- 4,120 17 2 1,400 25.1 7.6 7,140 <1.0 0.15 0.05 ---

CHN-810 129 4/10/01 

14:07

--- --- --- 4,200 9 <1 1,400 27.1 7.5 7,160 <1.0 0.05 0.05 ---

CHN811A Com- positea 4/11/01 13:10 --- --- --- 4,380 23 <1 1,500 22.6 7.5 7,580 <1.0 <0.05 0.2 ---TDW NA 4/11/01 

14:27

--- --- --- 140 114 8 170 23.0 8.3 237 7.2 0.1 <0.05 ---

CHN-809 112 4/12/01 

11:14

--- --- --- 2,060 25 <1 320 24.7 8.3 3,350 <1.0 0.1 <0.05 ---

CHN-809 129 4/12/01 

13:36

--- --- --- 2,770 4 <1 670 26.3 7.9 4,720 <1.0 0.2 <0.05 ---

CHN811A Com- positeb 4/13/01 8:39 --- --- --- 4,310 6 <1 1,500 24.5 7.5 7,400 <2.0 0.1 0.1 ---CHN-810 112 4/17/01 

11:29

--- --- --- 3,300 21 2 870 20.5 7.8 5,470 <1.0 0.1 <0.05 ---

CHN-810 129 4/17/01 

13:51

--- --- --- 3,790 3 <1 1,200 22.5 7.6 6,430 <1.0 0.1 <0.05 ---

CHN-809 129 4/20/01 

13:50

--- --- --- 2,030 <2 <1 390 25.2 8.7 3,310 <1.0 0.05 <0.05 ---

CHN-810 112 4/23/01 

11:29

--- --- --- 2,550 20 <1 530 24.9 8.0 4,280 <1.0 0.05 <0.05 ---

CHN-810 129 4/23/01 

14:28

--- --- --- 3,390 9 1 960 25.9 7.7 5,680 <1.0 0.05 <0.05 ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; μg/L, microgram per liter; ANC, acid neutralizing capacity; CaCO3, calcium carbonate; ---, data not available; NA, not applicable; E, estimated; TDW, treated drinking water; <, less than; M, presence verified, but not quantified]
76 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer Sample location (fig. 1; table 2) Sample depth, m bls Date/time (EST) Nitrogen ammonia (mg/L) Nitrate + nitrate, dissolved (mg/L) Nitrogen, nitrite (mg/L) Boron, dissolved 

(μg/L)

Iron, 

dissolved 

(μg/L)

Manganese, 

dissolved 

(μg/L)

Strontium, 

dissolved 

(μg/L)

Water 

temperature 

(

o C)

Field pH 

(su)

Field 

specific 

conductance 

(μS/cm)

Field 

dissolved 

oxygen, 

mg/L

Field 

iron, 

mg/L

Field 

sulfide, 

mg/L

Field 

chloride, 

mg/L

Cycle 4 (Continued)

CHN-810 112 5/2/01 

11:45

--- 0.69 0.58 2,080 177 4 310 24.6 8.2 3,120 <1.0 0.1 <0.05 ---

CHN-810 112 5/2/01 

11:46

--- 0.69 0.58 2,060 12 <1 320 --- --- --- --- --- --- ---

CHN-810 129 5/2/01 

14:17

--- 0.32 0.28 3,000 6 <1 780 23.3 7.7 4,950 <1.0 0.1 <0.05 ---

CHN-810 129 5/2/01 

14:18

--- 0.32 0.28 3,050 7 <1 760 --- --- --- --- --- --- ---

CHN-800 109 5/9/01 

11:22

--- <0.02 <0.01 3,970 375 10 2,300 27.4 7.7 10,100 <1.0 1.0 0.25 ---

CHN-810 112 5/18/01 

11:04

--- 0.69 0.55 1,690 16 1 260 27.1 8.6 2,510 <1.0 0.1 <0.05 ---

CHN-810 129 5/18/01 

13:16

--- 0.42 0.36 2,610 29 2 640 25.6 7.8 4,150 <1.0 0.1 <0.05 ---

CHN811A Com- positeb 5/22/01 12:26 --- 0.02 <0.01 4,200 11 <1 1,500 24.1 7.6 7,550 <1.0 0.1 <0.05 ---CHN-809 112 5/23/01 

11:40

--- 0.88 0.16 660 <2 <1 120 24.3 9.3 1,330 <1.0 0.1 <0.05 ---

CHN-809 112 5/23/01 

11:41

--- 0.87 0.15 660 3 <1 120 --- --- --- --- --- --- ---

TDW NA 5/23/01 

13:25

--- 0.24 <0.01 33 <2 3 50 27.8 8.5 215 6.8 0.1 <0.05 ---

CHN-809 129 5/23/01 

13:50

--- 0.68 0.15 1,110 2 <1 220 27.4 8.9 2,010 <1.0 0.1 <0.05 ---

CHN-809 112 5/31/01 

12:43

--- 0.90 0.32 600 <2 <1 99 29.4 9.4 1,220 <1.0 0.1 <0.05 ---

CHN-809 129 5/31/01 

15:08

--- 0.72 0.28 880 <2 <1 130 26.5 9.1 1,600 <1.0 0.1 <0.05 ---

CHN-810 112 6/5/01 

11:20

--- 0.56 0.58 1,470 <2 <1 190 26.0 8.5 2,210 <1.0 0.1 <0.05 ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; μg/L, microgram per liter; ANC, acid neutralizing capacity; CaCO3, calcium carbonate; ---, data not available; NA, not applicable; E, estimated; TDW, treated drinking water; <, less than; M, presence verified, but not quantified]
Appendixes 77

Sample 

location

(fig. 1; 

table 2)

Sample 

depth, 

m bls 

Date/time 

(EST)

Nitrogen 

ammonia 

(mg/L)

Nitrate + 

nitrate, 

dissolved 

(mg/L)

Nitrogen, 

nitrite 

(mg/L)

Boron, 

dissolved 

(μg/L)

Iron, 

dissolved 

(μg/L)

Manganese, 

dissolved 

(μg/L)

Strontium, 

dissolved 

(μg/L)

Water 

temperature 

(o C)

Field pH 

(su)

Field 

specific 

conductance 

(μS/cm)

Field 

dissolved 

oxygen, 

mg/L

Field 

iron, 

mg/L

Field 

sulfide, 

mg/L

Field 

chloride, 

mg/L

Cycle 4 (Continued)

CHN-810 129 6/5/01 

13:55

--- 0.36 0.37 2,230 <2 <1 460 29.9 8.0 3,570 <1.0 0.1 <0.05 ---

CHN-809 112 6/26/01 

11:56

--- 0.69 0.43 740 2 2 130 28.6 9.2 1,480 <1.0 0.1 <0.05 ---

CHN-809 129 6/26/01 

14:15

--- 0.57 0.35 1,000 <2 2 180 26.7 9.0 1,850 <1.0 0.1 <0.05 ---

CHN-810 112 6/27/01 

12:29

--- 0.44 0.46 1,470 <2 2 170 25.8 8.5 2,150 <1.0 0.1 <0.05 ---

CHN-810 129 6/27/01 

14:30

--- 0.27 0.27 2,320 <2 2 463 25.3 7.9 3,580 <1.0 0.1 <0.05 ---

CHN-809 112 7/17/01 

10:55

--- --- --- --- --- --- --- 28.3 9.2 1,610 <1.0 0.1 <0.05 ---

CHN-809 129 7/17/01 

13:09

--- 0.45 0.30 995 <2 <1 194 26.6 8.9 1,910 <1.0 0.1 <0.05 ---

CHN-810 112 7/19/01 

11:40

--- 0.36 0.32 1,440 5 <1 206 27.6 8.5 2,210 <1.0 0.1 <0.05 ---

CHN-810 129 7/19/01 

13:46

--- 0.20 0.19 2,270 2 1 486 25.2 7.9 3,680 <1.0 0.1 <0.05 ---

CHN-809 112 8/7/01 

12:24

--- 0.56 0.34 679 4 <1 114 28.8 9.5 1,440 --- 0.1 <0.05 ---

CHN-809 129 8/7/01 

14:56

--- 0.41 0.26 974 4 <1 159 28.7 9.3 1,840 --- 0.1 <0.05 ---

CHN-810 112 8/8/01 

12:22

--- 0.25 0.25 1,450 3 <1 193 29.7 9.0 2,020 --- 0.1 <0.05 ---

CHN-810 129 8/8/01 

14:40

--- 0.14 0.14 2,250 4 1 492 27.8 8.5 3,270 --- 0.1 <0.05 ---

CHN-809 112 8/22/01 

12:10

--- 0.49 0.33 701 4 <1 120 27.8 9.3 1,450 <1.0 0.1 <0.05 ---

CHN-809 129 8/22/01 

14:40

--- 0.36 0.24 962 2 <1 160 27.2 9.2 1,860 <1.0 0.1 <0.05 ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; μg/L, microgram per liter; ANC, acid neutralizing capacity; CaCO3, calcium carbonate; ---, data not available; NA, not applicable; E, estimated; TDW, treated drinking water; <, less than; M, presence verified, but not quantified]
78 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer Sample location (fig. 1; table 2) Sample depth, m bls Date/time (EST) Nitrogen ammonia (mg/L) Nitrate + nitrate, dissolved (mg/L) Nitrogen, nitrite (mg/L) Boron, dissolved 

(μg/L)

Iron, 

dissolved 

(μg/L)

Manganese, 

dissolved 

(μg/L)

Strontium, 

dissolved 

(μg/L)

Water 

temperature 

(

o C)

Field pH 

(su)

Field 

specific 

conductance 

(μS/cm)

Field 

dissolved 

oxygen, 

mg/L

Field 

iron, 

mg/L

Field 

sulfide, 

mg/L

Field 

chloride, 

mg/L

Cycle 4 (Continued)

CHN-810 129 8/23/01 

14:40

--- 0.10 0.10 2,300 7 1 490 25.0 8.3 3,680 <1.0 0.1 <0.05 ---

CHN-809 112 9/18/01 

12:02

--- 0.40 0.28 687 4 <1 110 25.7 9.6 1,390 <1.0 0.1 <0.05 ---

CHN-809 129 9/18/01 

14:43

--- 0.27 0.19 976 2 <1 160 27.7 9.3 1,850 <1.0 0.1 <0.05 ---

CHN-810 112 9/19/01 

11:46

--- 0.11 0.10 1,440 5 <1 210 26.1 8.7 2,170 <1.0 0.1 <0.05 ---

CHN-810 129 9/19/01 

14:08

--- 0.06 0.05 2,220 5 <1 460 25.2 8.2 3,570 <1.0 0.1 <0.05 ---

CHN-809 112 10/15/01 

11:52

0.89 0.26 0.25 800 4 M 152 25.6 9.1 1,590 <1.5 0.1 <0.05 ---

CHN-809 129 10/15/01 

14:12

0.86 0.19 0.17 1,020 5 M 182 24.9 9.0 1,930 1.0 --- --- ---

CHN-810 112 10/16/01 

12:18

0.74 0.04 0.04 1,480 7 <1 240 25.8 9.2 2,350 <1.5 0.1 <0.05 ---

CHN-810 129 10/16/01 

14:17

0.84 <0.02 <0.01 2,300 6 <1 510 24.7 8.7 3,680 1.0 0.1 <0.05 ---

CHN-812 NA 11/8/01 

14:40

0.49 <0.02 <0.01 106 7 20 87 25.1 7.9 399 <1.0 <0.05 <0.05 56

CHN-812 NA 11/9/01 

8:40

0.31 0.12 0.03 270 4 17 160 21.7 9.5 834 <1.0 0.05 <0.05 160

CHN-810 112 11/9/01 

13:00

1.9 <0.02 <0.01 2,890 144 6 850 23.5 7.2 5,140 <1.0 0.2 0.1 ---

CHN-810 129 11/9/01 

15:20

1.5 <0.02 <0.01 2,920 56

M 693 22.0 7.1 4,670 <1.0 0.1 <0.05 ---

CHN-812 NA 11/9/01 

16:10

0.30 0.14 0.04 347 3 15 180 23.2 7.4 1,030 <1.0 0.05 <0.05 190

CHN-812 NA 11/10/01 

10:20

0.43 0.09 0.04 549 3 11 215 23.0 8.4 1,300 <1.0 <0.05 <0.05 260

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; μg/L, microgram per liter; ANC, acid neutralizing capacity; CaCO3, calcium carbonate; ---, data not available; NA, not applicable; E, estimated; TDW, treated drinking water; <, less than; M, presence verified, but not quantified]
Appendixes 79aSample was collected from within the cased portion of the well after purging approximately 60 percent of one casing volume of water.

bSample was collected from within the cased portion of the well after purging three casing volumes of water.

Sample 

location

(fig. 1; 

table 2)

Sample 

depth, 

m bls 

Date/time 

(EST)

Nitrogen 

ammonia 

(mg/L)

Nitrate + 

nitrate, 

dissolved 

(mg/L)

Nitrogen, 

nitrite 

(mg/L)

Boron, 

dissolved 

(μg/L)

Iron, 

dissolved 

(μg/L)

Manganese, 

dissolved 

(μg/L)

Strontium, 

dissolved 

(μg/L)

Water 

temperature 

(o C)

Field pH 

(su)

Field 

specific 

conductance 

(μS/cm)

Field 

dissolved 

oxygen, 

mg/L

Field 

iron, 

mg/L

Field 

sulfide, 

mg/L

Field 

chloride, 

mg/L

Cycle 4 (Continued)

CHN-812 NA 11/10/01 

16:17

0.38 0.11 0.04 505 4 12 208 23.1 8.0 1,420 <1.0 0.05 <0.05 320

CHN-812 NA 11/11/01 

12:20

0.56 0.05 0.02 736 4 10 243 24.4 7.9 1,720 <1.0 <0.05 --- 420

CHN-809 112 11/13/01 

13:50

E1.6 <0.02 <0.01 2,670 27 M 673 23.0 8.3 4,570 <1.0 0.05 <0.05 ---

CHN-809 129 11/13/01 

16:20

1.3 <0.02 <0.01 2,520 18 M 553 20.9 8.3 4,340 <1.0 0.05 <0.05 ---

CHN-812 NA 11/13/01 

17:21

0.74 <0.02 <0.01 1,310 5 7 331 22.0 8.2 2,440 <1.0 <0.05 <0.05 500

CHN-812 NA 11/27/01 

16:30

0.59 <0.02 0.02 1,880 28 25 600 24.4 8.1 3,570 <1.5 --- --- ---

CHN-812 NA 12/6/01 

12:30

1.3 <0.02 <0.01 3,490 59 4 1,020 25.6 7.5 6,480 <1.0 0.1 <0.05 >2,500

CHN-809 112 12/18/01 

12:14

1.9 <0.02 <0.01 4,050 65 1 1,400 20.0 7.5 7,070 <1.0 0.1 0.1 ---

CHN-812 NA 12/18/01 

13:27

1.3 <0.02 <0.01 3,710 72 5 1,190 24.2 7.5 6,700 <1.5 0.1 <0.05 ---

CHN-809 129 12/18/01 

14:39

1.6 <0.02 <0.01 4,080 43 <1 1,330 21.5 7.5 6,950 <1.0 <0.05 <0.05 ---

CHN-809 112 2/14/02 

13:46

1.8 <0.02 <0.01 4,430 54 <2 1,500 21.3 7.4 7,250 <1.0 0.1 0.1 ---

CHN-809 129 2/14/02 

15:48

1.5 <0.02 <0.01 4,450 47 <2 1,420 21.3 7.4 7,260 <1.0 <0.05 <0.05 ---

CHN-810 112 2/15/02 

12:55

1.6 <0.02 <0.01 4,340 62 <2 1,410 16.2 7.4 7,680 <1.0 --- --- ---

CHN-810 129 2/15/02 

15:24

2.0 0.03 <0.01 4,310 97 <2 1,680 20.6 7.3 7,240 <1.0 0.1 <0.05 ---

CHN-812 NA 2/15/02 

16:06

1.6 <0.02 <0.01 4,250 76 <2 1,470 21.2 7.4 7,280 <1.0 0.1 0.1 ---

Appendix 1. Dissolved inorganic constituent concentrations and water-quality characteristics measured in samples collected during aquifer storage recovery testing in Charleston, South Carolina. — Continued[m bls, meter below land surface; EST, Eastern Standard Time; su, standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligram per liter; μg/L, microgram per liter; ANC, acid neutralizing capacity; CaCO3, calcium carbonate; ---, data not available; NA, not applicable; E, estimated; TDW, treated drinking water; <, less than; M, presence verified, but not quantified]
80 Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer

Appendix 2. Dissolved trihalomethane and chloride concentrations measured in samples collected during cycle 4 of the aquifer storage recovery study in Charleston, South Carolina.

[m bls, meter below land surface; EST, Eastern Standard Time; μg/L, microgram per liter; mg/L, milligram per liter; TDW, treated drinking water; NA, not applicable; ---, data not available; UPZ, upper production zone; <, less than; LPZ, lower production zone]

Sample 

location

Sample

depth,

m bls

Days 

(from start 

of injection)

Date/Time 

(EST)

Total 

trihalomethanea

(μg/L)

Dissolved 

chlorideb, 

mg/L

Chloroform, 

relative 

percentc

Dissolved 

chloride, 

relative 

percentc

TDW NA 8.97 4/11/01 14:27 --- 60 --- NA

TDW NA 9.89 4/12/01 12:37 57 --- NA ---

CHN-809 UPZ 112 9.84 4/12/01 11:14 14 680 0.56 0.63

CHN-809 UPZ 112 58.90 5/31/01 12:43 28 190 1.12 0.91

CHN-809 UPZ 112 84.87 6/26/01 11:56 22 230 0.88 0.89

CHN-809 UPZ 112 105.82 7/17/01 10:55 20 --- 0.80 ---

CHN-809 UPZ 112 126.89 8/7/01 12:24 19 210 0.76 0.90

CHN-809 UPZ 112 141.88 8/22/01 12:10 14 --- 0.56 ---

CHN-809 UPZ 112 168.87 9/18/01 12:02 19 230 0.76 0.89

CHN-809 UPZ 112 195.86 10/15/01 11:52 20 280 0.80 0.86

CHN-809 UPZ 112 224.95 11/13/01 13:50 --- 1,050 --- 0.42

CHN-809 UPZ 112 259.98 12/18/01 14:39 <4.0 --- NA ---

CHN-809 LPZ 129 9.94 4/12/01 13:36 9.2 1,100 0.37 0.39

CHN-809 LPZ 129 59.00 5/31/01 15:08 23 270 0.92 0.86

CHN-809 LPZ 129 84.96 6/26/01 14:15 17 340 0.68 0.82

CHN-809 LPZ 129 105.92 7/17/01 13:09 3 350 0.12 0.82

CHN-809 LPZ 129 126.99 8/7/01 14:56 15 320 0.60 0.83

CHN-809 LPZ 129 141.98 8/22/01 14:40 13 --- 0.52 ---

CHN-809 LPZ 129 168.98 9/18/01 14:43 16 340 0.64 0.82

CHN-809 LPZ 129 195.96 10/15/01 14:12 15 360 0.60 0.81

CHN-809 LPZ 129 225.05 11/13/01 16:20 --- 960 --- 0.47

CHN-810 UPZ 112 63.84 6/5/01 11:20 18 410 0.72 0.78

CHN-810 UPZ 112 107.85 7/19/01 11:40 15 410 0.60 0.78

CHN-810 UPZ 112 127.88 8/8/01 12:22 20 400 0.80 0.79

CHN-810 UPZ 112 142.90 8/23/01 12:42 16 --- 0.64 ---

CHN-810 UPZ 112 169.86 9/19/01 11:46 22 420 0.88 0.78

CHN-810 UPZ 112 196.88 10/16/01 12:18 --- 440 --- 0.77

CHN-810 UPZ 112 220.91 11/9/01 13:00 <4.0 1,150 NA 0.37

CHN-810 LPZ 129 63.95 6/5/01 13:55 10 750 0.40 0.59

CHN-810 LPZ 129 107.94 7/19/01 13:46 8.2 770 0.33 0.58

CHN-810 LPZ 129 127.98 8/8/01 14:40 12 760 0.48 0.59

CHN-810 LPZ 129 142.98 8/23/01 14:40 10 --- 0.40 ---

CHN-810 LPZ 129 169.96 9/19/01 14:08 13 800 0.52 0.56

CHN-810 LPZ 129 196.96 10/16/01 14:17 15 770 0.60 0.58

CHN-810 LPZ 129 221.01 11/9/01 15:20 <4.0 1,050 NA 0.42

CHN-812 NA 219.98 11/8/01 14:40 8.5 48 0.34 0.99
 81

a

Total trihalomethanes consist of chloroform, bromoform, bromodichloromethane, and chlorodibromomethane. Chloroform was the only constituent that 

contributed to the total trihalomethane concentration in ground-water samples. The chloroform concentration in the 4/12/2001 treated drinking-water sample was 

25 μg/L.

bAverage chloride concentrations for all treated drinking-water samples collected during this investigation was 27 mg/L. Native aquifer chloride concentration 

was 1,800 mg/L.

c

Percent of sample concentration that represents the contribution of chloroform or dissolved chloride from treated drinking water.

CHN-812 NA 220.73 11/9/01 8:40 4.5 150 0.18 0.93

CHN-812 NA 221.04 11/9/01 16:10 <4.0 190 NA 0.91

CHN-812 NA 221.80 11/10/01 10:20 <4.0 290 NA 0.85

CHN-812 NA 222.05 11/10/01 16:17 <4.0 260 NA 0.87

CHN-812 NA 222.88 11/11/01 12:20 4.1 360 0.16 0.81

CHN-812 NA 225.09 11/13/01 17:21 <4.0 580 NA 0.69

CHN-812 NA 239.06 11/27/01 16:30 <4.0 790 NA 0.57

CHN-812 NA 240.87 11/29/01 11:55 <4.0 --- NA ---

CHN-812 NA 247.89 12/6/01 12:30 <4.0 1,570 NA 0.13

CHN-812 NA 259.93 12/18/01 13:27 <4.0 1,560 NA 0.14

Appendix 2. Dissolved trihalomethane and chloride concentrations measured in samples collected during cycle 4 of the aquifer storage recovery study in Charleston, South Carolina. — Continued

[m bls, meter below land surface; EST, Eastern Standard Time; μg/L, microgram per liter; mg/L, milligram per liter; TDW, treated drinking water; NA, not applicable; ---, data not available; UPZ, upper production zone; <, less than; LPZ, lower production zone]

Sample 

location

Sample

depth,

m bls

Days 

(from start 

of injection)

Date/Time 

(EST)

Total 

trihalomethanea

(μg/L)

Dissolved 

chlorideb, 

mg/L

Chloroform, 

relative 

percentc

Dissolved 

chloride, 

relative 

percentc