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EVALUATION OF GEOPHYSICAL METHODS FOR THE DETECTION OF SUBSURFACE TETRACHLOROETHYLENE (PCE) IN CONTROLLED SPILL EXPERIMENTS
Citation:
MAZZELLA, A. EVALUATION OF GEOPHYSICAL METHODS FOR THE DETECTION OF SUBSURFACE TETRACHLOROETHYLENE (PCE) IN CONTROLLED SPILL EXPERIMENTS. Presented at EPA 2005 Science Forum, Washington, DC, May 16 - 18, 2005.
Impact/Purpose:
Research is being conducted to improve and evaluate the resolution of the CR, EM, seismic, and GPR methods over complex geological formations (such as fractured geologies) and to evaluate the capability of these geophysical methods to delineate subsurface organic contaminants.
Description:
Tetrachloroethylene (PCE), typically used as a dry cleaning solvent, is a predominant contaminant in the subsurface at Superfund Sites. PCE is a dense non-aqueous phase liquid (DNAPL) that migrates downward into the earth, leaving behind areas of residual saturation and free product pools on areas of low permeability. These can act as long-term sources of drinking water contamination. Effective remediation requires the location of the non-aqueous-phase PCE in the subsurface. The purpose of the current research is to evaluate the use of geophysical methods to detect this PCE. A series of controlled spill experiments have been conducted in which measurements with a number of geophysical methods were made before, during, and after the injection of PCE into the subsurface. These results clearly identified any geophysical anomaly associated with the PCE.
These experiments were conducted at the Canadian Forces Base Borden with the University of Waterloo and at the Oregon Graduate Institute with the U.S. Geological Survey (USGS). A number of different geophysical methods were tested in each of these experiments with good success. However, the presence of steel walls and tanks to contain the migration of the PCE prevented the evaluation of a number of geophysical methods. In order to evaluate these other geophysical methods, the current experiment was conducted with the Lawrence Berkeley National Laboratory (LBNL) in a non-metallic.