Theme: 05. Fractured Rock and Complex Geology

Topic Area: 5c. Remediation Approaches in Fractured Rock and Karst Aquifers

Formatted Title:

Complementary EISB Technologies for a Site with Glacial Outwash and Fractured Bedrock Contamination

Background/Objectives:

Geosyntec is designing and implementing an enhanced in situ bioremediation (EISB) remedial approach to address a chlorinated solvent plume (primarily trichloroethene [TCE]) in groundwater at a site in northern Indiana.

Approach/Activities:

The EISB remedy will target the Liston Creek limestone member, including the basal Red Bridge limestone, between depths of approximately 40 to 70 feet below ground surface. The conceptual site model at the facility is complex due to the presence of highly fractured zones of limestone which contain interbedded seams of glacial outwash materials and TCE concentrations as high as 800 mg/L have been observed in the bedrock. EISB injections will be completed using multiple approaches including use of a pressurized-packer system to effectively place EISB amendments into the highly variable subsurface lithologies. In addition, a permeable reactive barrier will be installed off-site utilizing micro-scale zero valent iron and Dehalococcoides species to address chlorinated solvent migration via sorption and enhanced reductive dichlorination.

Results/Lessons Learned:

The results of the packer testing and geophysics of the bedrock boreholes will be discussed as well as any lessons learned during the implementation of the EISB remedial approach. At the time of the presentation there will be approximately 6 months of EISB groundwater monitoring data.

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Jeannie Quenneville

Biography