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Publications > Versteeg and others, 2010.

Near real-time imaging of molasses injections using time-lapse electrical geophysics at the Brandywine DRMO, Brandywine, Maryland

R.J. Versteeg (roelof.versteeg@inl.gov)
Sky Research, Hanover, NH, USA

T. Johnson (tim.johnson.geo@gmail.com)
PNNL, Richland, WA, USA

B. Major (william.major@navy.mil)
NFESC, Port Hueneme, CA, USA

F.D. Day-Lewis (daylewis@usgs.gov)
BGAS-WRD, USGS, Storrs, CT, USA

J.W. Lane, Jr. (jwlane@usgs.gov)
BGAS-WRD, USGS, Storrs, CT, USA

Abstract

Enhanced bioremediation, which involves introduction of amendments to promote biodegradation, increasingly is used to accelerate cleanup of recalcitrant compounds and has been identified as the preferred remedial treatment at many contaminated sites. Although blind introduction of amendments can lead to sub-optimal or ineffective remediation, the distribution of amendment throughout the treatment zone is difficult to measure using conventional sampling. Because amendments and their degradation products commonly have electrical properties that differ from those of ambient soil, time-lapse electrical geophysical monitoring has the potential to verify amendment emplacement and distribution. In order for geophysical monitoring to be useful, however, results of the injection ideally should be accessible in near real time. In August 2010, we demonstrated the feasibility of near real-time, autonomous electrical geophysical monitoring of amendment injections at the former Defense Reutilization and Marketing Office (DRMO) in Brandywine, Maryland. Two injections of about 1000 gallons each of molasses, a widely used amendment for enhanced bioremediation, were monitored using measurements taken with borehole and surface electrodes. During the injections, multi-channel resistance data were recorded; data were transmitted to a server and processed using a parallel resistivity inversion code; and results in the form of time-lapse imagery subsequently were posted to a website. This process occurred automatically without human intervention. The resulting time-lapse imagery clearly showed the evolution of the molasses plume. The delay between measurements and online delivery of images was between 45 and 60 minutes, thus providing actionable information that could support decisions about field procedures and a check on whether amendment reached target zones. This experiment demonstrates the feasibility of using electrical imaging as a monitoring tool both during amendment emplacement and post-injection to track amendment distribution, geochemical breakdown, and other remedial effects.

Final copy as submitted to the American Geophysical Union for publication as: Versteeg, R., Johnson, T., Major, B., Day-Lewis, F.D., and Lane, J.L., Jr., 2010, Near real-time imaging of molasses injections using time-lapse electrical geophysics at the Brandywine DRMO, Brandywine, Maryland [abs.], in 2010 Fall Meeting, San Francisco, California, 13-17 December 2010, proceedings: American Geophysical Union, Washington, D.C., abstract H13G-02.