USGS Groundwater Information: Branch of Geophysics
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Geophysical Monitoring of Bio-Stimulation Pilot Study to Remediate Contaminated Ground Water, Fridley, Minnesota
As part of its applied research initiatives in FY2002, the USGS Office of Ground Water, Branch of Geophysics conducted geophysical experiments to monitor a U.S. Navy pilot bio-stimulation project to remediate groundwater contaminated with volatile organic compounds (VOCs) in Fridley, Minnesota.
At the Naval Industrial Reserve Ordnance Plant (NIROP), Fridley, Minnesota, areas contaminated by VOCs are being injected with vegetable oil as part of ongoing remediation efforts. As part of the monitoring efforts, the Branch of Geophysics conducted geophysical surveys to attempt to monitor the location of the oil. Toward this end, geophysical logs were collected before, during, and after injection of the vegetable oil.
The Branch of Geophysics has also been conducting research on the addition of tracers to the vegetable oil in order to alter the electrical and magnetic properties of the oil. Three separate injections at the NIROP site were monitored: one of pure vegetable oil, one of vegetable oil mixed with ferrofluids, and one of vegetable oil mixed with colloidal iron powder.
Borehole radar tomography and surface-to-borehole radar logs were collected in order to determine whether vegetable oil alone or vegetable oil mixed with one of the tracers allowed for the clearest imaging of the location and extent of the injected oil. In addition, a suite of standard borehole logs, including electromagnetic induction, magnetic susceptibility, neutron porosity, and gamma, were collected to aid in the interpretation of the radar logs.
This research was funded by the U.S. Navy with support from the USGS Toxic Substances Hydrology Program.
Lane, J.W., Jr., Day-Lewis, F.D., Versteeg, R.J., and Casey, C.C., 2003, Object-based inversion of crosswell radar tomography data to monitor vegetable-oil injection experiment, in Symposium on the Application of Geophysics to Engineering and Environmental Problems (SAGEEP), April 6-10, 2003, San Antonio, Texas, Proceedings: Denver, Colorado, Environmental and Engineering Geophysics Society, CD-ROM, 27 p.
View the online photo gallery from this project.