32 Hydrogeology

Added due to amount of discipline abstracts submitted.

Tuesday, 10 March 2026
1:30 PM - 5:30 PM
RCC, 106

Hydrostratigraphy Beneath the Memphis Regional Megasite, Western Tennessee, in a Regional Context

Paper number: 32-5
Program: Technical Sessions
Time: 2:45 PM – 3:00 PM

Authors

Abstract

Borehole stratigraphic data are commonly used for initial assessment of confinement in sedimentary aquifer systems.  Unconfined or semi-confined conditions for water supply aquifers beneath industrial sites create vulnerability to groundwater quality problems.  Initial analysis of available lithologic and geophysical borehole logs beneath the Megasite Authority of West Tennessee (MAWT) property in Haywood County suggests that the Memphis aquifer, the primary water supply aquifer in the region, is only partially confined. The MAWT is a 4,100-acre property that will be home to a vehicle assembly and battery manufacturing campus and supplier park, which are anticipated to consume 5 to 10 million gallons of groundwater per day once fully operational.  As part of a proactive strategy to assess and monitor hydrogeologic conditions at the MAWT, six sonic boreholes were drilled at the site with wells completed in the upper or middle Memphis aquifer. Thin Holocene or Pleistocene surface deposits (< 6 m) are disconformably underlain by Eocene Claiborne Group strata, including the Cockfield Formation, Cook Mountain Formation, and the Memphis Sand. The primary confining unit, the Eocene Cook Mountain Formation, is present in 5 of 6 boreholes drilled as part of this study. However, geophysical logs from construction of pre-existing production wells along the northern margin of the site suggest that the Cook Mountain Formation is absent in several of these boreholes. Regionally, the MAWT lies in a transitional zone between fully unconfined and mostly confined conditions.  The primary determinant of confinement across the transitional zone is the degree to which post-Cook Mountain incision and Cockfield Formation paleovalley sandy fill provide connection between the shallow aquifer system in the Cockfield Formation and younger deposits and underlying Memphis aquifer. Current water quality data at the MAWT do not indicate any water quality concerns; however, once the facilities are at full capacity the potential for vertical recharge will increase and the production wells may be more vulnerable to water quality issues.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1

doi: 10.1130/abs/2026SE-411720

© Copyright 2026 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.