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4.0 TECHNOLOGY IDENTIFICATION AND SCREENING <br /> A Feasibility Study(FS)was performed for the January 1998 CAP to identify and evaluate potentially <br /> ` feasible technology options and then develop and evaluate alternatives for groundwater remediation. <br /> Several technologies were evaluated. The list oftechnologies was then reduced to those that were felt to <br /> be technically feasible at the site given site specific conditions and use. Using these technologies, <br /> alternatives were developed that could potentially be implemented at the site. These alternatives were <br /> finally evaluated based on implementability,effectiveness,and cost. Technologies retained in the FS are <br /> described below for review. <br /> Also included in the technology identification and screening is consideration ofthe site for low risk closure. <br /> ` Currently,the site does not meet all ofthe criteria set forth by the California Environmental Protection <br /> Agency,Regional Water Quality Control Board(RWQCB),San Francisco Bay Region. WESTON has <br /> ` therefore identified the data gaps that need to be filled before the site can qualify for low risk closure as an <br /> alternative to active remediation technologies. <br /> r. 4.1 Technology Identification <br /> A review ofthe most promising technologies was completed using United States Environmental Protection <br /> Agency(EPA)databases,vendor information,and other sources. This review identified the following <br /> technologies that were retained for finiher consideration as showing some effectiveness for the treatment <br /> of BTEX and TPH-g sources and as having some applicability considering site conditions: <br /> • In situ Air Sparging(AS)/Soil Vapor Extraction(SVE) <br /> • In situ Bioremediation <br /> • Intrinsic Remediation with Monitoring <br /> Intrinsic remediation with monitoring was the final selected alternative in the January 1998 CAP and has <br /> been implemented at the site for 8 years. This alternative has been effective to date; however, the <br /> contaminants in the source area have not declined to a level that would indicate the site should be closed. <br /> ` To obtain a more timely goal of site closure, a more aggressive alternative will be necessary. <br /> 4.2 Technology Screening <br /> 4.2.1 In situ Air Sparging/Soil Vapor Extraction <br /> 4.2.1.1 Description <br /> ` An AS/SVE system consists of a network of AS wells installed into the saturated zone and SVE wells <br /> installed into the vadose zone. The network ofwells is designed so that the entire area requiring treatment <br /> is effectively aerated. Air compressors are used to deliver air under pressure,and vacuum pumps are used <br /> 9 <br />