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6 0 <br /> USA#10 September 2014 <br /> 2132 East Mariposa Road, Stockton <br /> Claim No: 6098 <br /> Rationale for Closure under the Policy <br /> • General Criteria: The case does not meet all eight Policy general criteria because <br /> secondary source remains <br /> • Groundwater Specific Criteria: The case does not meet Policy criteria because the <br /> contaminant plume that exceeds water quality objectives is greater than 100 feet in length <br /> and the dissolved concentration of benzene is greater than 3,000 micrograms per liter(ug/L) <br /> and the dissolved concentration of methyl tert-butyl ether (MTBE) is greater than 1,000 Ng/L. <br /> Additionally, high tert-butyl alcohol (TBA) concentrations are present in groundwater. <br /> • Vapor Intrusion to Indoor Air: The case meets the Policy Exclusion for Active Station. Soil <br /> vapor evaluation is not required because the Site is an active commercial petroleum fueling <br /> facility and the release characteristics do not pose an unacceptable health risk. <br /> • Direct Contact and Outdoor Air Exposure: This case meets Policy Criterion 3b. Although no <br /> document titled "Risk Assessment' was found in the files reviewed, a professional <br /> assessment of site-specific risk from exposure through the direct exposure pathway was <br /> performed by Fund staff. The assessment of site-specific risk from potential exposure to <br /> residual soil contamination found that maximum concentrations of petroleum constituents <br /> remaining in soil will have no significant risk of adversely affecting human health. The Site is <br /> paved and accidental exposure to site soils is prevented. As an active petroleum fueling <br /> facility, any construction worker working at the Site will be prepared for exposure in their <br /> normal daily work. <br /> Objections to Closure and Responses <br /> According to the Path to Closure page in GeoTracker, finalized on June 27, 2014, the County <br /> objects to UST case closure because: <br /> • Secondary source remains. <br /> RESPONSE: We concur. <br /> • The case does not meet Policy groundwater criteria. <br /> RESPONSE: We concur. <br /> Recommendation <br /> The Fund recommends that the County direct the Responsible Party to conduct groundwater <br /> remediation to achieve Policy guidelines in a timely manner. <br /> Kirk Larson, P.G. Date Robert Trommer, C.H.G. Date <br /> Engineering Geologist Senior Engineering Geologist <br /> Technical Review Unit Chief, Technical Review Unit <br /> (916) 341-5663 (916) 341-5684 <br /> Page 2 of 2 <br />