Radar Tomography and Borehole Geophysical Methods Used to Monitor Amendment Emplacement and Geochemistry Changes During Vegetable Oil Biostimulation

Overview

[Photo: USGS scientists conduct borehole radar survey.]

Peter Joesten (USGS OGW BG) (left, background) and Eric White (USGS OGW BG) (right, foreground) conduct borehole radar survey downgradient from U.S. Navy Naval Industrial Reserve Ordnance Plant, Fridley, Minnesota.

As part of its applied research initiatives, the USGS Office of Groundwater, Branch of Geophysics (OGW BG) collected and analyzed cross-hole radar and geophysical logging data collected from 2001 through 2003 to monitor a U.S. Navy pilot biostimulation project designed to remediate groundwater contaminated with chlorinated hydrocarbons in Anoka County Riverfront Park, Fridley, Minnesota.

Purpose & Scope

The U.S. Navy (Navy) conducted a bioremediation pilot study down gradient from the U.S. Navy Naval Industrial Reserve Ordnance Plant (NIROP) site in Fridley, Minnesota. For the pilot study, the Navy injected vegetable oil to stimulate biodegradation in areas contaminated by volatile organic compounds including trichloroethene (TCE) and dichloroethene (DCE). 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 were to characterize the spatial and temporal distribution of the injected fluid and to estimate the emulsion saturation between the wells used for surveying.

Methods & Activities

From 2001 through 2003, OGW BG collected borehole and surface-to-borehole geophysical data in the study area before, during, and after injection of the vegetable oil. 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

[Photo: USGS scientist collects radar data.]

Chris Kochiss (USGS OGW BG) holds radar receiver antenna in borehole during vertical radar profiling survey. Transmitter antenna is located on the ground surface in the foreground of the picture.

OGW BG also conducted research on the addition of tracers in order to alter the electrical and magnetic properties of the vegetable 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.

An innovative, object-based inversion method was developed for use in processing the cross-well data; this inversion method builds on understanding of the site's hydrologic and geologic characteristics in order to produce tomograms more immediately useful to engineers and hydrologists. Based on changes in the radar velocity data collected during surveys, models of the physical properties of the subsurface were developed in order to estimate vegetable oil emulsion saturation. Data from one image plane also were analyzed to estimate the distribution of the vegetable oil emulsion and emulsion saturation. These images could be used to determine how the oil is moving through the ground and to determine if changes in subsurface electrical conductivity are due to microbial activity or other factors that can be monitored using borehole radar methods.

Results & Conclusions

Analysis of cross-borehole radar and conventional borehole geophysical data provided insights into the spatial and temporal distribution of both the vegetable oil emulsion and the extent of groundwater with altered chemistry.
Radar traveltime data showed that the vegetable oil emulsion remained close to the three injection wells.
Over time, radar wave attenuation increased downgradient of the injection wells, indicating an increase in electrical conductivity and, therefore, total dissolved solids. The attenuation changes could result from biologically induced transformation of the aquifer sediments or biodegradation of the chlorinated-solvent contamination at the site.
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.

Support & Collaboration

This research was funded by the U.S. Naval Facilities Engineering Command, Southern Division, with support from the USGS Toxic Substances Hydrology Program. Alan Witten (Oklahoma University School of Geology and Geophysics) collaborated on the research.

Photo Galleries

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., Day-Lewis, F.D., and Casey, C.C., 2006, Geophysical monitoring of a field-scale biostimulation pilot project, Anoka County Riverfront Park, Fridley, Minnesota: Ground Water, v. 44, no. 3, p. 430-443, doi: 10.1111/j.1745-6584.2005.00134.x

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., Johnson, C.D., Joesten, P.K., and Kochiss,C., in press, Borehole geophysical monitoring of amendment emplacement and geochemistry changes during vegetable oil biostimulation, Anoka County Riverfront Park, Fridley, Minnesota: U.S. Geological Survey Scientific Investigations Report 2006-5199.

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.

Related Sites

U.S. Environmental Protection Agency web site for NIROP Superfund Site

For more information:

For more information on this project, please contact John W. Lane, Jr. (Chief, USGS OGW Branch of Geophysics) or Frederick Day-Lewis (Hydrologist, USGS OGW Branch of Geophysics), or call the Branch of Geophysics at (860)487-7402.

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USGS Programs and Offices can learn more about geophysical equipment available for USGS use and training and support from OGW BG.