SITE INFORMATION AND CORRESPONDENCE 2002 - 2013

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SITE CLOSURE AGE prepared a Closure Summary Report dated 19 October2012 requesting a No Further Action Required (NFAR) status for the site LUST investigation and for well destructions. The approximately residual mass of contaminates impacting soil was provided in Appendix C of the initial Closure Summary Report. The estimate was 3,987 lbs of gasoline less the volume removed from the two SVE pilot test or410 lbs remediated which equals 3,577 lbs of gasoline and an estimated 40,576 lbs of diesel fuels less the mass removed from the pilot tests of 39.6 lbs equals 40,536 lbs of diesel remaining. The estimated residual mass of the dissolved contaminate (1,2-dichloroethene: DCA) is estimated to be 0.14 lbs near the former UST area. RISC Workbench 5, a commercial risk assessment and fate and transport computer software program initially developed by British Petroleum Company, has been utilized to analyze future impacts to work occupants in the proximity of the contaminant source (UST area), and to assess human health risk; in addition, clean-up levels by all identified exposure routes were evaluated for commercial-type setting exposures, at the site. Currently no structures are located within a distance of the shallow petroleum soil impact which justifies soil vapor intrusion mitigation. Additionally, the model demonstrates that future structures will not have a significant risk of exposure to residual carcinogenic contaminates. The mass of dissolved DCA estimated for the site was 0.14 pounds and described in Section 5.2. of the Closure Summary Report. Only groundwater samples collected from monitoring well MW-5 contained consistently high concentrations of dissolved petroleum hydrocarbons, which is the former fuel additive DCA. The low permeability clayey soil at the site appears to be effectively limiting migration of the dissolved contaminant plume, and natural attenuation is reducing the concentrations of DCA over time. Analysis of contaminant trends in well MW-5 suggests that DCA will meet water quality objectives by year 2020. The CHEROKEE TRUCK STOP case is under consideration fora no further action closure by the San Joaquin County Environmental Health Department. Information requests for the site or public comments concerning the pending case closure can be submitted to Mr. Nuel Henderson by email at(nhenderson(CD_sicehd.com) by phone at 209-468-3420 or to the San Joaquin County Environmental Health Department 1868 East Hazelton Street, Stockton, California 95205. Comments must be submitted to the EHD no later than 28 February 2013.