Preliminary evaluation of the hydrogeology and groundwater quality of the Mississippi River Valley Alluvial Aquifer and Memphis Aquifer at the Tennessee Valley Authority Allen Power Plants, Memphis, Shelby County, Tennessee

Open-File Report 2018-1097
Prepared for the Tennessee Valley Authority in cooperation with the University of Memphis, Center for Applied Earth Science and Engineering Research
By: , and 

Links

  • Document: Report (8.07 MB pdf)
  • Data Release: USGS data release - Water-level models used to estimate drawdown in 32 monitoring wells screened in the Mississippi River Valley alluvial aquifer and 4 observation wells screened in the Memphis aquifer during an aquifer test at the Tennessee Valley Authority Allen power plants, Memphis, Shelby County, Tennessee, October 2017
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Abstract

The hydrogeology, groundwater quality, and potential for hydraulic connection between the Mississippi River Valley alluvial aquifer and the Memphis aquifer in the area of the Tennessee Valley Authority (TVA) Allen Combined Cycle and Allen Fossil Plants in southwestern Memphis, Tennessee, were evaluated from September through December 2017. The study was designed as a preliminary assessment of the potential for leakage of groundwater from the Mississippi River Valley alluvial aquifer through the underlying upper Claiborne confining unit into the underlying Memphis aquifer at the plants. A short-term aquifer test of four of the five Memphis aquifer production wells installed at the Allen Combined Cycle Plant induced drawdown in water levels in the Mississippi River Valley alluvial aquifer, locally. The largest drawdown occurred in the eastern and southeastern parts of the TVA plants area, and generally was coincident with locations where stratigraphic data show increased thickness of and depth to the base of the alluvium and decreased thickness and inferred offset in the base of the confining unit relative to nearby locations. In contrast, stratigraphic data for most other locations at the site indicate shallower depths to the base of the alluvium and more consistent thickness of and depth to the base of the confining unit, which corresponds with areas where less drawdown was observed during the test. Water-quality results for samples from the production wells and from monitoring wells screened in the Mississippi River Valley alluvial aquifer indicate that groundwater with higher dissolved-solids concentrations and tritium from this shallow aquifer has mixed with water in the upper part of the Memphis aquifer at one of the production wells. Results of the study collectively confirm that the Mississippi River Valley alluvial and Memphis aquifers are hydraulically connected near the TVA plants area.

Suggested Citation

Carmichael, J.K., Kingsbury, J.A., Larsen, Daniel, and Schoefernacker, Scott, 2018, Preliminary evaluation of the hydrogeology and groundwater quality of the Mississippi River Valley alluvial aquifer and Memphis aquifer at the Tennessee Valley Authority Allen Power Plants, Memphis, Shelby County, Tennessee: U.S. Geological Survey Open-File Report 2018–1097, 66 p., https://doi.org/10.3133/ofr20181097.

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Geology and Hydrogeology of the Study Area
  • Methods
  • Results
  • Summary and Conclusions
  • References
  • Appendix 1. SeriesSEE Water-Level Model Hydrographs—Allen Combined Cycle Plant Monitoring Wells
  • Appendix 2. SeriesSEE Water-Level Model Hydrographs—Allen Fossil Plant Monitoring Wells
  • Appendix 3. SeriesSEE Water-Level Model Hydrographs—Memphis Aquifer Observation Wells

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Preliminary evaluation of the hydrogeology and groundwater quality of the Mississippi River Valley Alluvial Aquifer and Memphis Aquifer at the Tennessee Valley Authority Allen Power Plants, Memphis, Shelby County, Tennessee
Series title Open-File Report
Series number 2018-1097
DOI 10.3133/ofr20181097
Year Published 2018
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Lower Mississippi-Gulf Water Science Center
Description Report: vii, 66 p.; Data Release
Country United States
State Tennessee
County Shelby County
City Memphis
Online Only (Y/N) Y
Additional Online Files (Y/N) Y