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i <br /> SECC www.secor.com <br /> i INTERNAf10NAL 3017 Kilgore Road , Suite 100 <br /> S E C O R <br /> INCORPORATED Cordova, CA 95670 <br /> 916-861 -0400 TEL <br /> 916-861 -0430 FAX <br /> October 17, 2006 <br /> � oh �', W LL�SI� LS VU LS <br /> OCT r 8 2006 <br /> Ms. Lori Duncan ENVIRONMENT HEALTH <br /> San Joaquin County PERMIT/SERVICES <br /> Environmental Health Department <br /> 304 East Weber Avenue, Third Floor <br /> Stockton, CA 95202 <br /> RE: Revised Work Plan for Soil Vapor Extraction and Air Sparge Feasibility <br /> Testing <br /> ARCO Service Station 548 <br /> 1612 West Hammer Lane <br /> Stockton, California <br /> SECOR Project No. : 77BP . 0548.00.0136 <br /> Dear Ms. Duncan : <br /> This letter, prepared by SECOR International Incorporated (SECOR) on behalf of Atlantic <br /> Richfield Company, a BP Affiliated Company, addresses the comments in the San Joaquin <br /> County Environmental Health Department (SJCEHD) letter dated August 28, 2006 <br /> (Attachment A). The letter was prepared in response to the SECOR workplan dated August <br /> 4, 2006 . The purpose of the work plan was to present the plan for conducting the required <br /> feasibility testing. The results of this test will be used to determine if SVE/AS is an <br /> appropriate remedial alternative for ARCO Service Station 548. <br /> As outlined in the workplan , a one-day SVE test is proposed to verify that the SVE system '1 <br /> will be capable of recovering the vapor concentrations during the AS testing . The SVE test i <br /> will be conducted using vapor wells VW-1 , VW-2, VW-3, VW4, and VW-5D. A vacuum will <br /> be induced and soil vapor will be extracted from each of the vapor wells. System influent <br /> and effluent samples will be collected during the test and may be used to determine anyS <br /> mass removal. <br /> After running the SVE system for one day, a one day air sparge well influence test will be , <br /> conducted on the AS wells . Baseline data will be collected from each of the site wells. This f <br /> information will be used to establish a background range for groundwater at this site. <br /> All site wells will be monitored at regular intervals during the test to determine the radius of\ <br /> influence of the AS wells. Depth to water and DO will be measured in the monitoring wells ! <br /> prior to, during , and at the end of the test. During the test induced pressure will be <br /> measured in the monitoring wells. The injection pressure, flow rate, and total time of <br /> injection will be monitored in the injection wells. This field data will be used to determine <br /> the effective radius of influence of air sparging at the site. <br /> During the test, the SVE system will be run to capture any fugitive vapors . The SVE system <br /> influent will be monitored for the presence of hydrocarbon vapors using a flame ionization <br /> detector ( FID). An increase in FID readings at the influent of the SVE system could indicate <br />