April 2004 Meeting

Monday, April 12, 2004
6:00 - 7:30 pm

Pellissippi State Technical Community College
10915 Hardin Valley Road, Knoxville
Lamar Alexander Building
Room 223


Hydrogeology and Implications of Leakage
Between Aquifer Units in the Northern Mississippi Embayment

Randy W. Gentry, PhD, PE
Director, Southeastern Water Resources Institute
Civil & Environmental Engineering
University of Tennessee
Knoxville, Tennessee 37996


Research is being conducted to better understand the hydraulics and risk posed by leakage between a shallow alluvial aquifer and the deeper semi-confined Memphis aquifer. Two study areas will be discussed: 1) the Shelby Farms study site, where an aquitard window is located near an abandoned landfill, and 2) the Sheahan wellfield, where an aquitard window is thought to exist in an urban area of Memphis. Previous research by the U.S. Geological Survey determined the suspected locations of the aquitard windows, and research is now focused on using environmental tracers to better understand the leakage hydraulics. Tritium and 3-Helium samples have been used to determine the apparent age of water within the mixing zone of the Memphis and overlying alluvial aquifer. In addition, geochemical models have been used to describe probable mixing ratios. The data can be used to determine a preliminary framework for understanding the risk to the aquifer in areas where leakage is likely occurring.


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