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Harding Lawson Associates <br /> V DESCRIPTION OF SELECTED REMEDIAL ACTION <br /> A. General Project Description <br /> The proposed remedial action involves: <br /> ' • Design and installation of a trench capable of <br /> performing soil venting and groundwater extraction. <br /> • Treating the excavated soils from the trench on site. <br /> ' 0 Installation of a soil vapor extraction system (VES) <br /> utilizing the trench and existing lateral piping in the <br /> former tank pit area. <br /> • Treatment of the hydrocarbon air emissions from the <br /> ' VES. <br /> • If VES does not reduce hydrocarbon concentrations, then <br /> groundwater will be extracted from the trench in <br /> con unction with soil vapor extraction. <br /> • Treatment of the extracted groundwater prior to <br /> Ndischarge to the storm drain. <br /> The soil vapor extraction system will be operated prior to <br /> groundwater treatment. After operation has progressed for a <br /> period of time in which the effectiveness of the system can be <br /> evaluated, a determination can be made to whether groundwater <br /> pumping and treatment will be necessary. Vapor extraction will <br /> remove any floating free product in the vicinity of the trench so <br /> 1 extracted groundwater can be pumped directly through GAC vessels <br /> ' without additional expense to install and operate an oil-water <br /> separator. <br /> ' The groundwater and soil vapor extraction systems can be <br /> installed and operated in the same treatment area (see Plate 7) . <br /> ' If necessary, they can also be operated concurrently. Where <br /> ! possible, monitoring wells will be utilized as passive air inlet <br /> ' 20 <br />