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COR <br /> �F International Incorporated <br /> 2 PM 1: 39 <br /> April 26, 2002 <br /> Project CH77.43508.00.0570 <br /> Mr. Bob Cochran <br /> Chevron Products Company <br /> P.O. Box 6004 <br /> San Ramon, California 95843 <br /> Re: 1st Quarter 2002 Remedial System Evaluation Report <br /> Chevron Service Station#9-4275 <br /> 2905 West Benjamin Holt Drive <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 /> r of the remedial systems effectiveness during the 0 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 December 14, 2001 and March 5, 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 monitorg wells at the site ranged from 7.39 <br /> to 9.86 feet below ground surface on March 11, 20 , The screened intervals in the <br /> 'SVE wells range from 10 to 13 feet below ground surface (bgs) (Figure 2); therefore <br /> water levels are currently too high for the effective operation of the SVE system. Prior <br /> to shutdown, the SVE system has extracted approximately 70 pounds of gasoline from <br /> the soil and groundwater beneath the site. <br /> The inactive SVE system is comprised of ten SVE wells (VW-1 and GM-i 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 This permit was rescinded at Chevron's request in 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.secor.com <br />