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r _ I SECOR fllfL'1'71CIllU)?C1�f17G01�)U1'L1fBCl , r R w 11 April 13, 2001 Project 077.41991.034 Mr. Bob Cochran Chevron Products Company P.O. Box 6004 San Ramon, California 95843 Re: First Quarter 2001 Remedial System Evaluation Report Chevron Service Station#94275 2905 West Benjamin Holt Drive Stockton, California Dear Mr. Cochran: SECOR International Incorporated (SECOR) on behalf of Chevron Products Company (Chevron), presents operational data for the performance of the soil vapor extraction (SVE) and air sparging (AS) systems operating at the above referenced site (Figure 1). Operation of the SVE system began in September 1997 and AS system operation began in April 1997. A brief description of the remedial system, and performance evaluation of the remedial system for the first quarter of 2001 (December 14, 2000 through March 1, 2001) are presented below. Soil Vapor Extraction System The SVE system is comprised of ten SVE wells (VW-1 and GM-1 through GM-9), a 5- horsepower(hp) positive-displacement blower, and a 100-cubic feet per minute (cfm) catalytic oxidizer (Figure 2). The SVE system is operated under Permit No. N-3645•-1-0 issued by the San Joaquin County Unified Air Pollution Control District, which expires on March 1, 2002. i The SVE system has not been operated at the site since February 1998 due to high groundwater levels. Depth to water in the monitoring wells at the site ranged from 5.94 to 8.0 feet below ground surface on March 1, 2000. The screened intervals in the SVE wells range form 10 to 13 feet below grade (Figure 2), therefore water levels are currently too high for the effective operation of the SVE system. Prior to shutdown, the SVE system has extracted approximately 70 pounds of gasoline from the soil and groundwater beneath the site. .301; Kilgore Road, Suilr 100, Rrrnrhu Currinrrr. (.';I 95070 916 N01.0-i OU 91O.IM1.0430 Fax rrrrtr.sc(cor.c'01)1