HR: 0800h
AN: NS51A-02    [Abstracts]
TI: Using Groundwater Point Velocity Probes and Ground Penetrating Radar to Investigate Microbially Mediated Changes in Flow Properties of a Contaminated Aquifer
AU: * Schillig, P
EM: schillig@ku.edu
AF: Dept. of Geology University of Kansas, Lindley Hall rm. 120 1475 Jayhawk Blvd., Lawrence, KS 66045, United States
AU: McGlashan, M
EM: mam10@ku.edu
AF: Dept. of Geology University of Kansas, Lindley Hall rm. 120 1475 Jayhawk Blvd., Lawrence, KS 66045, United States
AU: Devlin, J F
EM: jfdevlin@ku.edu
AF: Dept. of Geology University of Kansas, Lindley Hall rm. 120 1475 Jayhawk Blvd., Lawrence, KS 66045, United States
AU: Tsoflias, G
EM: tsoflias@ku.edu
AF: Dept. of Geology University of Kansas, Lindley Hall rm. 120 1475 Jayhawk Blvd., Lawrence, KS 66045, United States
AU: Roberts, J
EM: jenrob@ku.edu
AF: Dept. of Geology University of Kansas, Lindley Hall rm. 120 1475 Jayhawk Blvd., Lawrence, KS 66045, United States
AB: In the practice of aquifer remediation, groundwater velocity is an essential parameter for determining contaminant fate and transport, and calculating residence times for passive treatment technologies such as reactive barriers. Over the past decade, there has developed an increased reliance on natural attenuation of various contaminants in porous media, and much of the attenuation is associated with biological processes that might affect local groundwater velocities. The point velocity probe (PVP), was recently developed to directly measure centimeter- scale groundwater velocities. The PVP velocity estimates are based on a mini tracer-test completed around the circumference of a small cylinder emplaced in the aquifer. The PVP functions without a well and therefore requires no calibration. Also, velocity calculations are independent of Darcy's Law, thus eliminating the need for hydraulic gradients that can usually only be measured over scales much larger than those of local microbial effects. The development of the PVP instrument raises the possibility of measuring velocity changes associated with biological activity in porous media. Field and laboratory studies confirm the PVP consistently and accurately measures groundwater velocity in porous media. An array of multilevel PVPs instrumented throughout a flow gate in the Borden aquifer coupled with borehole radar and tomographic methods were consistent in identifying changes in spatial heterogeneities apparently associated with the evolution of a petroleum hydrocarbon plume. The hydrocarbons were released into the aquifer and then subject to stimulated biodegradation using oxygen release compound (ORC) in wells up-gradient of the PVP array. Observed temporal changes in the heterogeneous properties of the Borden aquifer were attributed to enhanced biological activity with changing groundwater velocities corresponding spatially to areas of ORC application and greatest plume attenuation. To compliment PVP and radar field observations, a large-scale laboratory experiment is underway investigating both biological growth and activity as mechanisms for flow and dielectric property variations in the contaminated aquifer material.
UR: http:www.people.ku.edu/~jfdevlin/Research.html
DE: 0416 Biogeophysics
DE: 0448 Geomicrobiology
DE: 0614 Biological effects
DE: 1829 Groundwater hydrology
SC: Near-Surface Geophysics [NS]
MN: 2007 Joint Assembly