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sECoR International Incorporated November 5, 2002 Project 77CH 94275 010570 Mr Bob Cochran Chevron Environmental Management Company P O Box 6004 San Ramon, California 95843 Re Third Quarter 2002 Remediation System Status Report Chevron Service Station 9-4275 2905 West Benjamin Holt Drive Stockton, California Dear Mr Cochran SECOR International Incorporated (SECOR) presents with this letter operational data for the air sparge (AS) system operating at the subject site (Figures 1 and 2), and an evaluation of the remediation system's effectiveness during the 3rd quarter of 2002 QQ02) • The AS system began operation at the site in April 1997 in conjunction with a soil vapor extraction (SVE) system The SVE system has been disabled and the AS continues to operate A brief description and performance evaluation of the remedial system between June 19, 2002 and September 3, 2002 are presented below Soil Vapor Extraction System (Inactive) 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 8 80 to 12 21 feet below ground surface (bgs) on September 24, 2002 The screened intervals in the SVE wells range from 10 to 13 feet bgs thereforewater levels are currently too high for the effective operation of the SVE system The inactive SVE system is comprised of ten SVE wells (VW-1 and GM-1 through GM-9), buried mechanical piping, a 5-horsepower (hp) positive-displacement blower, and a 100-cubic feet per minute (cfm) catalytic oxidizer (Figure 2) The SVE system was permitted to operate under San Joaquin County Unified Air Pollution Control District Permit No N-3645-1-0 This permit was rescinded at Chevron's request in May 2001 3017 Kilgore Road, Suite 100, Rancho Cordova, CA 95670 916 861 0400 916 861 0430 Fax www secor corn