|Ground Water Institute Receives $310,000 to Remap Water Levels
For release: Sept. 22, 2005
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Memphis has some of the highest quality drinking water in the country. Thanks to recent gifts, the Ground Water Institute (GWI) in the University of Memphis' Herff College of Engineering plans to help prolong that distinction. The GWI has received $310,000 in grants, gifts, and in-kind services to remap water levels in the shallow aquifer that lies beneath much of Shelby County and supplies localized drinking water.
The Tennessee Department of Environment and Conservation (TDEC) made a $125,000 grant, which was matched by the Shelby County government. The U.S. Geological Survey (USGS) will match a portion of these research dollars with an additional $50,000 of in-kind service. Cargill Sweeteners donated $10,000 and Velsicol Chemical, Premier Environmental Services, and Memphis Light, Gas & Water Division are providing in-kind support.
Remapping the water levels of the shallow aquifer is important because of its connection to the deeper Memphis aquifer through breaches in the protective clay layer separating the two systems. The shallow aquifer is of poorer quality than the Memphis aquifer and is known to be contaminated in spots. The Memphis aquifer is the primary drinking water source for Shelby County and the surrounding region.
Continual pumping from the Memphis aquifer since the late 1800s has dropped its level so that water from the shallow aquifer now moves vertically downward into the Memphis aquifer. "This poorer quality water leaking from the shallow aquifer downward into the Memphis aquifer is a concern; it can ultimately affect the quality of our drinking water," said Dr. Brian Waldron of the GWI. "We have only a limited understanding of where this leakage is occurring and even less about the quantity of leakage."
Remapping will help increase scientists' understanding of how water levels in the shallow aquifer have changed since 1987, the last and only time the water levels were mapped at the county scale. "We know that the water levels in the shallow aquifer have changed since 1987," Waldron said. "In proximity to known breaches in the protective clay layer, water levels have declined as the potential for leakage to the Memphis aquifer has increased. We have been limited in our ability to predict the sustainability and future quality of our drinking water because of the lack of information on the shallow aquifer. This effort is a step in right direction."
Remapping the water levels in the shallow aquifer will involve taking water level measurements, collecting historical water levels for the last five years, measuring river and tributary stages at major bridge crossings, taking water level measurements in the Memphis aquifer, and measuring discharge along the Wolf and Loosahatchie Rivers and Nonconnah Creek. The water level survey will begin this fall with a resulting map expected by spring 2006.
"Another benefit of remapping the shallow aquifer water levels will be our increased ability to identify anomalous depressions in the water table that would indicate a possible breach in the protective clay layer," said Waldron. "Identified depressions will be investigated further in the spring and summer of 2006 using an innovative technology called seismic reflection to map the subsurface geology, thereby identifying whether clay exists or is absent."
Millsaps College of Jackson, Miss., and the Center for Earthquake Research and Information at the U of M will also play important roles in conducting the seismic reflection survey.
"This effort is truly a multi-disciplinary, multi-agency effort," Waldron said. "Without our partners, this effort would fall short of providing the information needed for us to understand our ground water better. This effort will also provide an opportunity for two students to receive master's degrees. Are we still seeking partners? Sure."The 18-month project is scheduled to be completed by December 2006.
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