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QPCOR <br /> International Incorporated <br /> August 6, 2002 AUG 0 8 2002 <br /> Project CH77 43508 00 0570 ENVIRONMENT HEALTH <br /> PERMIT/SERVICES <br /> Mr Bob Cochran <br /> Chevron Products Company <br /> P O Box 6004 <br /> San Ramon, California 95843 <br /> Re 2nd Quarter 2002 Remedial System Evaluation Report <br /> Chevron Service Station#9-4275 <br /> 2905 West Benjamin Holt Dnve <br /> Stockton, California <br /> Dear Mr Cochran <br /> SECOR International Incorporated (SECOR) presents with this letter operational data <br /> for the air sparge (AS) system operating at the subject site (Figure 1), and an evaluation <br /> of the remedial systems effectiveness during the 2nd quarter of 2002 <br /> The AS system began operation at the site in April 1997 in conjunction with a soil vapor <br /> extraction (SVE) system The SVE system has been disabled and the AS continues to <br /> operate A brief description and performance evaluation of the remedial system <br /> between March 5, 2002 and June 19, 2002 are presented below <br /> Inactive Soil Vapor Extraction System <br /> The SVE system has not been operated at the site since February 1998 due to high <br /> groundwater levels Depth to water in the monitoring wells at the site ranged from 8 39 <br /> to 10 71 below ground surface on June 6, 2002 The screened intervals in the SVE <br /> wells range from 10 to 13 feet below ground surface (bgs), therefore water levels are <br /> currently too high for the effective operation of the SVE system Prior to shutdown, the <br /> SVE system has extracted approximately 70 pounds of gasoline from the soil and <br /> groundwater beneath the site <br /> The inactive SVE system is comprised of ten SVE wells (VW-1 and GM-1 through <br /> GM-9), buried mechanical piping, a 5-horsepower (hp) positive-displacement blower, <br /> and a 100-cubic feet per minute (cfm) catalytic oxidizer (Figure 2) The SVE system <br /> was permitted to operate under San Joaquin County Unified Air Pollution Control <br /> District Permit No N-3645-1-0 This permit was rescinded at Chevron's request in <br /> May 2001 <br /> 3017 Kilgore Road, Suite 100, Rancho Cordova CA 95670 916 861 0400 916 861 0430 Fax www wor com <br />