Geophysical Monitoring of a Biostimulation Pilot Study to Remediate Contaminated Ground Water, Fridley, Minnesota - FY2004

As part of its applied research initiatives in FY2004, the USGS Office of Ground Water, Branch of Geophysics (OGW BG) continued analysis and interpretation of cross-hole radar and geophysical logging data collected to monitor a U.S. Navy pilot biostimulation project designed to remediate groundwater contaminated with chlorinated hydrocarbons in Anoka County Riverfront Park, Fridley, Minnesota.

Down-gradient from the Naval Industrial Reserve Ordnance Plant (NIROP), Fridley, Minnesota, areas contaminated by chlorinated hydrocarbons have been injected with vegetable oil to stimulate biodegradation of chlorinated hydrocarbons. As part of the remediation monitoring efforts, OGW BG conducted geophysical surveys before, during, and after injection of the vegetable oil. The goals of the geophysical monitoring are to characterize the spatial and temporal distribution of the injected fluid and to estimate the emulsion saturation between the wells used for surveying.

During FY2004, the field data were processed and interpreted. Results of the field experiments helped to provide spatial and temporal information about the distribution of vegetable-oil emulsion in the subsurface and demonstrated that changes in electrical conductivity due to microbial activity or other aqueous geochemistry change resulting from biostimulation can be monitored using borehole radar methods.

Radar zero-offset slowness profiles and slowness-difference tomograms indicate the vegetable-oil emulsion remained close to the injection wells, whereas radar attenuation profiles and electromagnetic (EM) logs indicate increases in bulk electrical conductivity downgradient of the injection zone, diagnostic of changing water chemistry. In several cases, the geophysical data indicate that the plume of groundwater with altered chemistry would not be detected by direct sampling given the depth of monitoring well screens; hence geophysical data provide a context for interpretation of water samples and evaluation of the biostimulation effort.

View the online image gallery from this project.

This research was funded by the U.S. Naval Facilities Engineering Command, Southern Division, with support from the USGS Toxic Substances Hydrology Program.

This research was conducted by Fred Day-Lewis and John W. Lane, Jr. (USGS OGW BG) with assistance from OGW BG staff.

Recent Publications:

Lane, J.W., Jr., 2003, Time-lapse geophysics for aquifer characterization and remediation monitoring [abs.]: EOS Transactions, American Geophysical Union, v. 84, no. 46, Fall Meeting Supplement, abstract H21F-01.

Lane, J.W., Jr., Casey, C.C., Day-Lewis, F.D., Witten, A., and Versteeg, R.J., 2004, Use of borehole radar methods and borehole geophysical logs to monitor a field-scale vegetable oil biostimulation pilot project at Fridley, Minnesota, in Proceedings of the Fourth International Conference on Remediation of Chlorinated and Recalcitrant Compounds, May 24-27, 2004, Monterey California, Proceedings: Battelle Memorial Institute, CD-ROM, 9 pages.

Lane, J.W., Jr., Day-Lewis, F.D., Versteeg, R.J., and Casey, C.C., 2004, Object-based inversion of crosswell radar tomography data to monitor vegetable oil injection experiments: Journal of Environmental & Engineering Geophysics, v. 9, no. 2, p. 63-77.

Lane, J.W., Jr., Day-Lewis, F.D., Versteeg, R.J., Casey, C.C., and Joesten, P.K., 2004, Application of cross-borehole radar to monitor field-scale vegetable oil injection experiments for biostimulation, in Symposium on the Application of Geophysics to Engineering and Environmental Problems (SAGEEP), 22 to 26 February, 2004, Colorado Springs, Proceedings: Denver, Colorado, Environmental and Engineering Geophysical Society, CD-ROM, 20 p.

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.

Witten, A., and Lane, J., 2003, Offset vertical radar profiling: Leading Edge, v. 22, no. 11, p. 1070-1076.

For related information, see:

• Summary of OGW BG FY2002 research at Fridley site
• Summary of OGW BG FY2003 research at Fridley site
• Summary of OGW BG FY2003 development of advanced radar processing methods
• Summary of OGW BG FY2004 development of advanced cross-hole radar processing methods