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SECOR <br /> r. '; 1 ` i..� , ;A LS-Al- llernalional Incorporaled <br /> 01 jUL 16 PM 2, 16 <br /> July 13, 2001 <br /> Project 077.43508.570 <br /> Mr. Bob Cochran <br /> Chevron Products Company <br /> P.O. Box 6004 <br /> San Ramon, California 95843 <br /> Re: Second Quarter 2001 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 air sparge (AS) system operating at the subject site (Figure 1), and an evaluation of <br /> • the remedial systems effectiveness during the 2nd quarter of 2001. <br /> An AS system operation began in April 1997 at the site in conjunction with a vapor <br /> extraction system (VES). The VES has been disabled and the AS continues to operate. <br /> A brief description and performance evaluation of the remedial system between March <br /> 1, 2001 and June 4, 2001 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 5.94 <br /> to 8.0 feet below ground surface on March 1, 2000. The screened intervals in the SVE <br /> wells range form 10 to 13 feet below grade (Figure 2), 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 is <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 This permit was rescinded at Chevron's request in 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, Suile 100, Rarrcbo Cordova, CA 95670 916.861.0400 916.861.0430 Fax wiviv.secor.com <br />