FINAL REPORT Development of Permeable Reactive Barriers (PRB) Using Edible Oils SERDP Project ER-1205

DNAPL Dense Non-aqueous Phase Liquid DO dissolved oxygen DOC dissolved organic carbon DoD Department of Defense DWEL Drinking Water Equivalent Level EOS ® Thermal Conductive Detector TCE Trichloroethene (Trichloroethylene) TOC Total Organic Carbon VC vinyl chloride VOC Volatile Organic Compound VS Volatile Solids ix ACKNOWLEDGEMENTS The research described in this report was conducted by a team of graduate students at North Carolina State University under the direction of Dr. Robert C. Borden. Kapo Coulibaly conducted the initial research on emulsion preparation and transport. Yong Jung conducted the three dimensional sand box experiments. Ximena Rodriguez and Cameron Long conducted the batch and column experiments that demonstrated the efficacy of emulsified oils for bioremediation of chlorinated solvents. We also gratefully acknowledge the excellent support provided by M. in the field portions of this project. The research described in this final project report was supported by the Department of Defense (DoD), through the Strategic Environmental Research and Development Program (SERDP). Dr. Andrea Leeson and other SERDP staff are gratefully acknowledged for their assistance and support. At the start of this project, neat and emulsified vegetable oil had been used at several different sites to simulate anaerobic biodegradation of chlorinated solvents and other contaminants in groundwater. However, little was known about the transport, retention and biodegradation of these materials in the subsurface or the impact of these materials on contaminant fate. This project included a series of laboratory, field and numerical modeling studies aimed at improving our understanding of edible oil transport and fate in the subsurface. This information was then used to develop an effective process for enhancing in situ anaerobic biodegradation of ground water contaminants. Preliminary laboratory experiments were conducted to develop methods for distributing edible oils away from the point of injection and to evaluate the effect of the injection method on aquifer permeability. Neat soybean oil could be distributed short distances in laboratory columns packed with sand without excessive permeability loss if the oil was be displaced to residual saturation. However in the field, oil displacement to residual saturation would likely be very difficult because of the high viscosity of the soybean oil and the large volumes of injection water required. If the oil is not displaced to residual saturation, permeability losses will be much greater and there is potential for upward migration of the oil due to buoyancy effects. In contrast, injection of edible oil-in-water emulsions offered many advantages …