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Groundwater Availability, Geochemistry, and Flow Pathways to Public-Supply Wells in the Atlantic Coastal Plain and Bedrock Aquifers, Aiken County and Part of Lexington County, South Carolina, 2015–2019

Scientific Investigations Report 2022-5036
Water Availability and Use Science Program
Prepared in cooperation with Aiken County, City of Aiken, Breezy Hill Water and Sewer Company, Inc., Gilbert-Summit Rural Water District, and Montmorenci-Couchton Water & Sewer District, Inc.
By:  and 
https://doi.org/10.3133/sir20225036

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  • Document: Report (13.3 MB pdf) , XML
  • Data Release: USGS data release - MODFLOW–NWT and MODPATH 5 used to evaluate groundwater availability, geochemistry, and flow pathways to public-supply wells in the Atlantic Coastal Plain and bedrock aquifers, Aiken County and part of Lexington County, South Carolina, 2015–2019
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Abstract

Between 2015 and 2019, the U.S. Geological Survey (USGS) studied concerns related to projected increases in demand for groundwater, in collaboration with municipal water providers and county managers within the study area, Aiken County and part of Lexington County, South Carolina. A three-dimensional (3D), numerical groundwater-flow model of the Atlantic Coastal Plain (ACP) aquifers, confining units, and the underlying bedrock aquifer in the study area was constructed using the USGS software program MODFLOW–NWT in conjunction with a groundwater-recharge model using the Soil-Water-Balance (SWB) model. Water budgets for dry (2012) and wet (2015) year conditions, future (2017–2065) groundwater-demand scenarios based on general circulation models (GCMs) of future climates, and future agricultural irrigation demands were simulated. Overall, the GCMs projected increased recharge rates. Simulation of projected increased demand on groundwater by agriculture irrigation indicated little drawdown in the study area.

Groundwater-quality samples were collected from representative public-supply wells (PSWs) and analyzed in the field and laboratory. In general, the groundwater in the ACP aquifers is acidic, dilute, and oxic. Conversely, groundwater in the bedrock aquifer was of neutral pH, mineralized, and anoxic. Total-radium concentrations across all PSWs ranged from 0.55 to 6.69 picocuries per liter (pCi/L). Groundwater from some PSWs contained detectable but low concentrations of commonly and historically used volatile organic compounds, such as chloroform, methyl tert-butyl ether (MTBE), cis-1,2-dichloroethylene (cis-1,2-DCE), 1,1-dichloroethane (1,1-DCA), and 1,1-dichloroethylene (1,1-DCE). The stable isotopes of groundwater sampled from all wells indicate the possibility that groundwater from the bedrock aquifer may discharge into the ACP. Finally, groundwater age-dating results and MODPATH simulations indicate recharge between the 1950s and 1980s for PSWs in the ACP and recharge between the 1940s and 1950s for PSWs in bedrock. Maximum groundwater-flow pathways ranged from 270 to 7,470 feet, with the longest simulated-flow pathway for wells pumped at higher rates.

Suggested Citation

Campbell, B.G., and Landmeyer, J.E., 2023, Groundwater availability, geochemistry, and flow pathways to public-supply wells in the Atlantic Coastal Plain and bedrock aquifers, Aiken County and part of Lexington County, South Carolina, 2015–2019: U.S. Geological Survey Scientific Investigations Report 2022–5036, 117 p., https://doi.org/10.3133/sir20225036.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Project Overview
  • Introduction
  • Description of the Study Area
  • Methods
  • Results and Discussion
  • Model Uncertainties and Limitations
  • Summary and Conclusions
  • References Cited
  • Appendix 1. Soil-Water-Balance Model
Publication type Report
Publication Subtype USGS Numbered Series
Title Groundwater availability, geochemistry, and flow pathways to public-supply wells in the Atlantic Coastal Plain and bedrock aquifers, Aiken County and part of Lexington County, South Carolina, 2015–2019
Series title Scientific Investigations Report
Series number 2022-5036
DOI 10.3133/sir20225036
Year Published 2023
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) South Atlantic Water Science Center
Description Report: xiv, 117 p.; Data Release
Country United States
State South Carolina
County Aiken County, Lexington County
Online Only (Y/N) Y
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details