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San Joaquin County DIRECTOR <br /> Donna Heran,REHS <br /> PO <br /> PIN Environmental Health Department ASSISTANT DIRECTOR <br /> 600 East Main Street Laurie Cotulla,REHS <br /> uai amply Stockton, California 95202-3029 pROGRAM COORDINATORS <br /> LLS11,:-. 4, Carl Borgman, REHS <br /> • Mike Huggins, REHS.RDI <br /> c :. ;P Website: wwW.sjgov.org/ehd Margaret Lagor o,REHS <br /> 4 /F 6 R� Phone: (209)466-3420 Robert McClellan, REHS <br /> Fax: (209)464-0136 Jeff Carruesco,REHS,RDI <br /> Kasey Foley,REHS <br /> 16 January 2008 <br /> Mr. George Teranishi and Ms. Mei Teranishi <br /> 1600 Durham Ferry Road <br /> Tracy CA 95376 <br /> Subject: Former Georges Service <br /> 1600 Durham Ferry Road <br /> Tracy CA 95376 <br /> San Joaquin County Environmental Health Department (EHD) has received and <br /> reviewed Work Plan, Sentinel Well Installation (Well WP), dated 26 September <br /> 2007, and Remedial Action Plan, Soil Vapor Extraction and Oxygen Releasing <br /> Compound (RAP) dated 29 November 2007, prepared on your behalf by your <br /> consultant Geological Technics, Inc. (GTI). <br /> The Well WP contains a proposal to install two sentinel wells in the sand unit <br /> commonly encountered between 30 and 35 feet below surface grade (bsg). The <br /> proposed wells will have 2.5-foot screen intervals set at approximately 32.5 to 35 <br /> feet bsg. The wells will be situated between the contaminant source area and the <br /> domestic water wells located at 31488 Highway 33 and at 1600 Durham Ferry <br /> Road. The purpose of the wells is to detect contaminants migrating through the <br /> sand unit toward the domestic wells. The EHD approves this scope of work as <br /> necessary and adequate as part of your corrective action [Health & Safety Code <br /> (H&S) Section 25299.37(c)(3)] <br /> GTI proposes in the RAP to remediate impacted groundwater on site through in <br /> situ air sparging (IAS) and a soil vapor extraction (SVE) system, and to address <br /> impacted groundwater offsite through application of oxygen releasing compound <br /> (ORC) or oxygen releasing compound advanced (ORC Advanced). The onsite <br /> system would consist of nine IAS wells installed near the former underground <br /> storage tank (UST) excavation and at other points on the site and a blower <br /> attached to pipes previously installed in the excavation backfill for vapor <br /> extraction. Extracted hydrocarbon vapor would be treated utilizing activated <br /> carbon canisters. <br /> The offsite groundwater remediation system would consist of three lines of <br /> borings arranged perpendicular to the groundwater flow direction; the borings <br /> would be filled with ORC or ORC Advanced as solids in 'socks', as solids, or as a <br /> slurry. The purpose for utilizing ORC or ORC Advanced is to stimulate biological <br /> WP Comment Letter 0108.doc <br />