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r <br /> `Sol �r <br /> 9.0 PROPOSED ALTERNATIVE FOR REMEDIATION <br /> An evaluation of alternatives has shown Alternative 1 - Passive Remediation and Alternative 2 - <br /> r <br /> Soil Excavation and off-site disposal to be less attractive for this site. RESNA proposes to <br /> remediate hydrocarbon-bearing soil beneath the site by installing and operating a vapor extraction <br /> system (VES) and continue groundwater monitoring to ensure that groundwater has not been <br /> impacted. The purpose of the VES is to remediate soil to reduce the Ieaching potential of <br /> petroleum hydrocarbons into the groundwater. The system will include three vapor extraction <br /> wells, vapor phase carbon for the treatment of off-gas, a water condenser and associated piping. <br /> Based on the results of the vapor extraction test conducted by RESNA, the radius of influence <br /> for vapor extraction within the impacted zone exceeds 30 feet. Wells VW-1, VW-2 and VW-3 <br /> are screened from approximately 20 to 50 feet below surface grade. These extraction wells <br /> should be capable of providing air flow through soil containing residual hydrocarbons (Plate 6). <br /> The three existing vapor extraction wells would be connected to a VES to draw hydrocarbon <br /> vapors out of the soil. The major components of the VES are 1) a regenerative blower system <br /> for drawing vapors from soil; 2) a condensate removal system for removing trapped condensate <br /> in the vapor extraction piping; 3) two vapor phase carbon vessels connected in series for treating <br /> vapors; and 4) collection system piping, other associated piping, control valves and <br /> instrumentation. The proposed location of the remediation compound and the piping system <br /> between the compound and vapor extraction wells are shown on Plate 8. <br /> The results of the vapor extraction test dictate a wellhead design flow of up to 100 cubic feet <br /> per minute (cfm) per well, or a total maximum design flow of 280 cfm. The design vacuum is <br /> 30-inches of water column. Based on the design parameters it is estimated that the VES will <br /> operate for approximately one year. <br /> 1500471REP0R151CAP-0694.FNL 16 <br />