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Vintage Car Wash -5- 13 May 2013 sot E Miner Ave.,Stockton San Joaquin County Public Participation Public participation was conducted from 5 October 2012 to 4 December 2012 with no adverse comments received by this agency. Low Risk Closure Policy(LTCP)Review The Site qualifies for a low risk closure under the State Water Resources Control Boom Low Risk Closure Policy,based on the following rationale: Groundwater Specific Criteria - 1.2 The nearest supply wells are 1,000'from the site,grommearte-plume is less than 2W'long, the monitoring well data indicate a low probability that the plume will leave the Site. Benzene concentration is less in.3,000 ug/L and MTBE is less than 1,000 ug/L. See above Table 2 and Figure 1 B. The offsite residual plume concentrations are below WOGs. Maximum nsite benzene was 510 uglL and all MTBE was<5 ug/L Petroleum Vapor lntrichum to lndoorht - 2a.1.Scenario 4 Under Measurement of Soil Gas Concentrations(1 of 2)Sal Gas Sampling— No Bioaffenuation Zone:Future Construction the soilgas samples shall be collected 6om at Most5'belowthegmundsurface. The Direct Measurement of Soil Gas Concentrations for Benzene,EfhyMenzene,antl Naphthalene shall notexceed LTCP Soil Gas Criteria for Residential and Commercial Soil Gas Conentrattons. The Site soil v r maximum results for benzene(B,26.52 ug/m3,Figure 17),ethylbenzene (E,28.22 ug/mrand naphthalene(N,non dialect at<28.83 ughn)passed the State Water Resources Control Board Low Threat Closure Policy(LTCP)Soil Gas Criteria for Residential B(<85 ug/m3),E(<1,100 ug/m3),and N(<93 ugtm)with no bioattenuation zone. Note that B.E,and N are the sole LTCP constituents used to evaluate risk from vapor intrusion, with or wftmut a bioathouation zone. There are no pre-existing soil concentration levels to be met for no bioattenuation zone. The 2007 soil vapor samples were taken at 5'bgs in a vacant lot,and fulfill the requirement for a vapor survey for future construction. Direct Contact antl Outdoor Air Exposure 3.a As a result ofcontmlling exposure through Me use of mitigation measures or through Me use asserftuttunal or englneertng controls,the regulatory agency communes that the concentrations ofpetroleum constituents in sal will have no significant risk of adversely affecting human health. See above Table 1. One shallow(4'bgs)soil confirmation sample taken under piping in 1993 exceeded the LTCP residential,commercial/industrial and utility worker limits for ethylbenzene, and residential and commemiaMndustrial limits for benzene. Three 1990 soil samples at greater depths defined the vertical extent of the soil contamination, Soil vapor sampled near the soil