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San Joaquin County <br /> .� Environmental Health Department DIRECTOR <br /> G <br /> Q: 2� 600 East Main Street Donna Heran, REHS <br /> N' k ;{ Stockton, California 95202-3029 PROGRAM COORDINATORS <br /> Robert McClellon,REHS <br /> Jeff Carruesco, REHS, RDI <br /> 09�� •ci\P Website: www.sjgov.org/ehd Kasey Foley,REHS <br /> Fos Phone: (209)468-3420 Linda Turkatte, REHS <br /> Fax: (209)464-0138 <br /> August 5, 2011 <br /> Mr. John Johnson <br /> Former Cheaper Store Number 37 <br /> 765 Eubanks Drive, Suite D <br /> Vacaville, California 95688 <br /> Subject: Former Cheaper Store Number 37 <br /> 15 East Grant Line Road <br /> Tracy, California 95376-2720 <br /> Dear Mr. Johnson: <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed Addendum <br /> to Soil Gas Study Activities (addendum), dated 26 May 2011, prepared and submitted by ATC <br /> Associates Inc. (ATC) on your behalf for the above-referenced site. In the addendum, ATC <br /> presented results from a Tier 2 soil gas evaluation using data from soil gas sample SG2 <br /> analyzed by the mobile laboratory. The EHD had directed the submittal of this evaluation by <br /> letter dated 01 April 2011. <br /> ATC completed a human health risk assessment (HHRA) using the Johnson and Ettinger <br /> model to calculate the potential cancer risk posed by vapor intrusion of hazardous chemicals <br /> associated with an unauthorized release from the former underground storage tanks removed <br /> from the site in 1988. ATC calculated a hazard quotient of 1.0E-03 and a carcinogen risk of <br /> 2.7E-07. These results did not exceed the threshold value of 1.0 for the hazard quotient, nor <br /> 1.0E-06 for cancer risk. Based on these results, ATC recommended this site be considered <br /> for closure following low risk guidelines. <br /> The EHD concurs with-this recommendation and directs that a closure summary report be <br /> submitted to this agency by 29 September 2011. Contaminant concentrations detected in soil <br /> gas samples SG2 through SG4 had exceeded the soil vapor Tier 1 Environmental Screening <br /> Levels for total petroleum hydrocarbons as gasoline (TPH-g) established by the California <br /> Regional Water Quality Control Board, San Francisco Bay Region; however, the human health <br /> and environmental risks associated with the high TPH-g concentrations had not been <br /> addressed in the addendum. The health risk to humans and the environment posed by the <br /> high concentrations of TPH-g must be adequately addressed in the closure summary report. <br /> Also provide an estimate when groundwater contaminant concentrations at this site will return <br /> to water quality objectives (WQOs) as established by the California Regional Water Quality <br /> Control Board Central Valley Region's Basic Plan. <br />