|Ground Water Institute Will Conduct Seismic Surveys
For release: April 11, 2006
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The University of Memphis announced today that the Herff College of Engineering's Ground Water Institute (GWI), in collaboration with the University's Center for Earthquake Research and Information and Millsaps College, will be performing preliminary seismic surveys on the city's subsurface to assess the integrity of the overlying protective clay unit to the Memphis Aquifer. The research will begin April 24th and be completed by May 7th.
This study is the test phase for the full-scale survey scheduled for July, which will identify new breaches, if any, in the clay layer. If breaches are found, water of poorer quality could potentially compromise the protective nature of the clay and enter our drinking water.
"The Mid-South region is very fortunate to have a valuable ground-water resource beneath its feet. In fact, the continued economic development and growth of the region can be linked to the long-term sustainability and quality of this natural resource," said Dr. Brian Waldron, associate director of the GWI. "The Memphis aquifer, our primary source for drinking water, is largely protected by an overlying clay unit. Past investigations have shown that localized breaches do exist that could allow for water of lesser quality to leak into the aquifer."
Waldron goes on to assert that the potential for leakage has risen as ground-water levels in the Memphis aquifer have declined during the past few decades. However, seismic reflection should provide a better understanding of the conditions under which breaches may exist.
Seismic reflection is an innovative methodology being employed by researchers at the University's GWI, where a jolt of energy is applied at the ground surface, which moves through the subsurface. The energy will travel faster or slower depending on the soil density. Geophones, or listening devices laid out on the ground surface, record the reflection of energy over time. Differences in travel times of the energy through the subsurface will ultimately reveal its true structure, such as the presence or absence of clay.
"A recent seismic survey at Shelby Farms revealed a southeast-northwest trending breach north of the Shelby County landfill and Walnut Grove, west and south of Farm Road and east of the Wolf River," Waldron added. "The structure and orientation of the breach in the protective clay layer suggests a paleo-channel, a very old erosional scar of a possibly ancient Wolf River channel."
GWI researchers also stated a variety of energy sources and geophone geometries will be performed to determine the optimum test conditions prior to the full-scale seismic reflection surveys that will be conducted later this summer.
About the Ground Water Institute
Established in 1992 at the Herff College of Engineering, the Ground Water Institute (GWI) is an organization of faculty, graduate and undergraduate students and non-academicians dedicated to becoming a locus of expertise in ground water management in Memphis. The GWI seeks to understand, improve and protect current and future ground water quantity and quality through research education and application.
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