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Remedial Action Plan and Further Site Assessment 7 7-Eleven Store No 19976 1399 N Main St Manteca CA May 30 2000 groundwater recovery system This would substantially reduce the costs of above-ground treatment of extracted groundwater Review of soil types indicates air sparginglvapor extraction is likely feasible 42 Electrokinesis Electrokinesis is a remediation method involving generation of an electric charge in the saturated zone, which in turn generates heat and mass transfer of hydrocarbons from the liquid to the vapor phase,where they can be removed by soil vapor extraction Electrodes are inserted Into the soil (typically from the top to the base of the plume) and 3-phase alternating current electric power is applied through the electrodes ' Resistivity in the soils during the current passage through the sod pore water generates heat, volatilizing the hydrocarbon vapors into the vadose zone Current transmission is confined to the subsurface, but the power generation unit is located in an above-ground enclosure along with vapor abatement equipment Typical electrode spacing is 15-20 feet apart regardless of soil type I rFeasibility criteria include the presence of permeable strata in the vadose zone (to allow for effective vapor extraction), and the presence of silty/clayey strata in the saturated zone (required to conduct the electric charge) In addition, electroktnesis applied as a barrier across the downgradient edge of the site must be physically located at least 30 feet from any subsurface metallic structures (i a USTs, dispensing piping, fittings, and utilities) Review of subsurface soil types indicates that the lithology is appropriate for this type of remediation, and the USTsldispenser island piping may be located about 30 feet from the downgradient edge of the i property(this distance needs to be more carefully verified, using subsurface piping diagrams and/or a utility survey) Due to the application of heat, this supplemental remediation method may be more effective than air-sparging sod vapor extraction rAs an augmentation to groundwater extraction, this remediation method could be implemented upgradient of the extraction point, potentially reducing dissolved hydrocarbon concentrations prior to removal by the groundwater recovery system This would substantially reduce the costs of above-ground treatment of extracted groundwater 43 Enhanced Intrinsic Biodegradation Enhanced intrinsic (in-situ) biodegradation usually includes the introduction of microbes (plus applicable nutrients)to create a population of MTBE-consuming microorganisms sufficient to eliminate the MTBE