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San Joaquin County <br /> °."'" .� Environmental Health Department DIRECTOR <br /> Donna Heran, REHS <br /> 1868 East Hazelton Avenue <br /> < PROGRAM COORDINATORS <br /> Stockton, California 95205-6232 Robert NicClellon,REHS <br /> Jeff Carruesco, REHS,RDI <br /> • c Kasey Foley,REHS <br /> q���O.Rci Website: www.sjgov.org/ehd Linda Turkatte, REHS <br /> Phone: (209) 468-3420 Rodney Estrada,REHS <br /> Fax: (209) 464-0138 Adrienne Ellsaesser, REHS <br /> September 19, 2014 <br /> Ms. Sharon Evans Mr. Chris Panaitescu <br /> Phillips 66 Company Thrifty Oil Company <br /> 1380 San Pablo Avenue 13116 Imperial Highway <br /> Rodeo, California 94572 Santa Fe Springs, California 90670 <br /> Subject: Phillips 66 Station No. 5449/former Thrifty Oil Company Site No. 172 <br /> 7647 Pacific Avenue RWQCB File No. 390652 <br /> Stockton, California 95207 SJCEHD Case No. 1227 <br /> Dear Ms. Evans and Mr. Panaitescu: <br /> The San Joaquin County Environmental Health Department (EHD) has received and reviewed <br /> Work Plan for a Soil Vapor Intrusion Study (Work Plan), dated 12 August 2014, prepared and <br /> submitted by your consulting firm, Cardno ATC (Cardno), on your behalf for the above- <br /> referenced site. By letter dated 19 May 2014, the EHD had directed the submittal of a work plan <br /> to collect data to evaluate the risk to human health and the environment posed by contaminated <br /> soil gas. <br /> In the Work Plan, Cardno proposed to collect one indoor air sample over a period of six to eight <br /> hours inside the 7-Eleven convenience store using a Summa canister; the exact location for <br /> collecting the air sample within the store was not identified, nor was the proposed volume of the <br /> Summa canister to be used to collect the indoor air sample. Cardno also proposed to collect <br /> one outdoor ambient air sample approximately fifty to one-hundred feet away from the site <br /> structure "in the prevailing up-wind direction over a similar duration as the indoor sample." <br /> Again the proposed volume of the Summa canister to be used to collect the outdoor air sample <br /> was not specified. <br /> The EHD has reviewed the soil gas analytical results reported for the five samples (SV-1 <br /> through SV-5) collected on 2.4 February 2012 in the context of the Low-threat Closure Policy <br /> (LTCP) criteria adopted by the State Water Resources Control Board on 17 August 2012. <br /> Several of the soil gas samples were collected less than five feet below surface grade (bsg) <br /> because soil conditions obstructed either the advancement of direct-push drilling rods to five <br /> feet bsg and/or the flow of soil gas at five feet bsg. Of the five samples collected, only one soil <br /> gas sample, SV-4, contained benzene concentrations [102 micrograms per cubic meter (pg/m3)j <br /> that exceeded the LTCP criteria for residential property with no bioattenuation zone. All of the <br /> soil gas sample results met the LTCP criteria for commercial property with no bioattenuation <br /> zone; however, the leak detector, 1,1-difluoroethane (1,2-DFA) was detected at low <br /> concentrations in two of the soil gas samples. Based on this information, the EHD is of the <br /> opinion that the collection of an indoor air and outdoor ambient air sample is not warranted at <br /> this time and the EHD does not approve the proposals submitted in the Work Plan. <br />