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San Joaquin County <br /> Environmental Health Department DIRECTOR <br /> o.• c Donna Heran, REHS <br /> ). <br /> r.' �--��—� i 1868 East Hazelton Avenue <br /> Q. I Stockton, California 95205-6232 PROGRAM COORDINATORS <br /> Robert McClellon, REHS <br /> Jeff Carruesco, REHS,RDI <br /> Kasey Foley,REHS <br /> P Website: WWWSjgov.org/ehd Linda Turkatte,REHS <br /> CA�l F pR�\ <br /> Phone: (209) 468-3420 <br /> Fax: (209) 464-0138 <br /> July 16, 2012 <br /> Mr. Dung Thanh Phan and Ms. Nhuan Thi Phan <br /> 3524 Morningside Drive <br /> Stockton, California 95219 <br /> Subject: California Stop <br /> 2224 Manthey Road <br /> Stockton, California 95206 <br /> Dear Mr. and Ms. Phan: <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed Soil Vapor <br /> Extraction Pilot Test Report— March 2012 (report), dated 19 April 2012, prepared and submitted <br /> by your consulting firm Advanced GeoEnvironmental, Inc. (AGE) on your behalf. In the report <br /> AGE presented results from performing an eight-hour soil vapor extraction (SVE) pilot test by <br /> applying a vacuum at SVE well VW-1 and measuring induced vacuums at observation wells <br /> VW-2, VW-3, MW-1, MW-3 and MW-8. AGE determined that the effective radius of influence <br /> was approximately 75 feet in shallow soil vapor wells, and calculated that approximately 1.2 <br /> pounds of total petroleum hydrocarbons as gasoline (TPH-g) were extracted during the pilot <br /> test. Based on these results, AGE concluded that soil vapor extraction would likely be effective <br /> in remediating the residual soil contamination in the vadose zone. <br /> AGE also concluded that "based on historically elevated concentrations of fuel additive <br /> constituents (methyl tertiary-butyl ether) MTBE and (tertiary-butyl alcohol) TBA in groundwater, <br /> and the relative absence of the above constituents in soil vapor samples during the 8-hour pilot <br /> study, it appears that at least two distinct releases may have occurred at the site." Noting this, <br /> AGE has recommended that two additional borings be advanced near the eastern and southern <br /> underground storage tank (UST) area "to evaluate additive adsorbed impact," and that the <br /> borings be converted into additional vapor extraction wells if significant petroleum hydrocarbon <br /> contamination were detected. <br /> The EHD has reviewed historical soil and groundwater analytical data collected at this site. Soil <br /> samples collected in 2005 from borings B1, advanced approximately ten feet east of the USTs, <br /> and B2, advanced approximately 10 feet south of the USTs, were reported with moderate <br /> concentrations of MTBE and TPH-g between 15 and 25 feet below surface grade (bsg). Grab <br /> groundwater samples collected frorn these borings were also reported with high concentrations <br /> of these two constituents. The EHD believes the analytical data from these two borings are <br /> sufficient to warrant one additional soil vapor extraction well to be installed near B2 to <br />