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IN <br /> SECOR www.secor.com <br /> I INTERNATIONAL 57 Lafayette Circle,21d Floor <br /> S o INCORPORAT€D Lafayette,CA 94549 ) <br /> l 925-299-9300 7E <br /> 925-299-9302 FAX <br /> 1 May 24, 2006 <br /> 1 .;I <br /> Ms JtiLori Duncan <br /> I San;Joaquin County I <br /> i. Environmental Health Department (EHD) l <br /> 304;East Weber Avenue, 3rd Floor i <br /> Stockton, CA 96202 <br /> Re: Air Sparge/Soil Vapor Extraction Treatment System ,(ASISVETS) Installation <br /> Quarterly Groundwater Monitoring and Reporting l <br /> Caltrans Shop 10 Maintenance Station, 1603 South;B Street in Stockton, CA <br /> Dear Ms. Duncan: <br /> SECOR International Incorporated (SECOR) has been retained to provide environmental <br /> services for the Department of Transportation (Caltrans),�iShop110 Maintenance Station <br /> located at 1603 South B Street in Stockton, California (Site). Current planned work i <br /> includes installation, operation and maintenance (O&M)'i of an Air Sparge/Soil Vapor <br /> Extraction Treatment System (AS/SVETS), and continued quarterly groundwater <br /> monitoring for fuel hydrocarbons in groundwater associated with underground storage <br /> tanks (USTs) formerly located at the Site. I <br /> SITE REMEDIATION, AS/SVETS�INSTALLATION I <br /> Installation of the approved AS/SVETS is scheduled for June and July 2005 and SECOR <br /> is c'trrently completing applications for permits, finalizing p1re-installation planning, <br /> procuring equipment, and scheduling contractor services. i System installation will follow <br /> approved drawings in the Caltrans document entitled, Soil Vapor Extraction and Air <br /> Sparging Performance Monitoring Plan, dated June 2003- The ASISVETS includes a <br /> r King'Buck Technology (KBT) catalytic oxidizer with 7.5 hp blower, to be used for SVE and <br /> a 7.5 hp rotary screw (RS) compressor for air sparging. Installation of four AS wells to 93 <br /> feetjibelow grade surface (bgs) and two SVE wells to a total depth of 30 feet bgs (not <br />} shown in Figure) is currently scheduled for June 1 through 10, 20 ,P <br /> 5, <br /> Syst m maintenance will include condensate removal, �is nosin systemproblems, <br /> ,i diagnosing Y <br /> recording system parameters, and maintaining equipment to 'optimize operation and <br /> maximize operating time. Soil vapor samples will be collected monthly to calculate mass <br /> removal rates, monitor cleanup progress, and to satisfy air permit discharge requirements. k <br /> System operation data and performance evaluation will be included with groundwater <br /> monitoring results in Quarterly Operations, Maintenance and Monitoring (OM&M) Reports. <br /> Vap ur system samples will be collected monthly from system influent and effluent locations, <br /> andanalyzed for benzene, toluene, ethylbenzene, and xylenes :(BTEX); total petroleum <br /> I <br /> 1:1CALTRANS1Stockton-Shop 101GW MonitoringlLetter to SJ County_Final.doc May 24,2005 <br /> Project No.940T.43148.00 SECOR International Incorporated <br /> i <br />