SITE INFORMATION AND CORRESPONDENCE

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Pacific Car Wash August 2014 4405 Pacific Avenue, Stockton Claim No: 12325 petroleum hydrocarbon constituents are limited and stable, and concentrations are decreasing. Corrective actions have been implemented and additional corrective actions are not necessary. Any remaining petroleum hydrocarbon constituents do not pose a significant risk to human health, safety or the environment. Rationale for Closure under the Policy • General Criteria: The case meets all eight Policy general criteria. • Groundwater Specific Criteria: The case meets Policy Criterion 1 by Class 5. Reportedly, two domestic water supply wells lie within 1,000 feet of the defined plume boundary. One well is 250 feet east and the second well is 400 feet west of the Site. Water is provided to water users near the Site by the Stockton East Water Department and the California Water Service. Otherwise, the case meets Policy Criterion 1 by Class 4. The contaminant plume that exceeds water quality objectives is less than 1,000 feet in length. There is no free product. The nearest surface water body is greater than 1,000 feet from the defined plume boundary. The dissolved concentrations of benzene and methyl tert-butyl ether(MTBE) are each less than 1,000 micrograms per liter (Ng/L). The regulatory agency determines, based on an analysis of site specific conditions, which under current and reasonably anticipated near-term future scenarios, the contaminant plume poses a low threat to human health and safety and to the environment and water quality objectives will be achieved within a reasonable time frame. • Vapor Intrusion to Indoor Air: The case meets the Policy Exclusion for Active Station. Soil vapor evaluation is not required because the Site is an active commercial petroleum fueling facility and the release characteristics do not pose an unacceptable health risk. • Direct Contact and Outdoor Air Exposure: This case meets Policy Criterion 3b. Although no document titled 'Risk Assessment'was found in the files reviewed, a professional assessment of site-specific risk from exposure through the direct exposure pathway was performed by Fund staff. The assessment of site-specific risk from potential exposure to residual soil contamination found that maximum concentrations of petroleum constituents remaining in soil will have no significant risk of adversely affecting human health. The Site is paved and accidental exposure to site soils is prevented. As an active petroleum fueling facility, any construction worker working at the Site will be prepared for exposure in their normal daily work. Objections to Closure and Responses By January 29, 2014 letter, the County recommends that rebound monitoring is conducted following the cessation of active remediation. Monitoring should include the sampling of nearby domestic wells. RESPONSE: We concur. Recommendation The Fund concurs with the County that rebound monitoring should be conducted. Kirk Larson, P.G. Date RobertTrommer, C.H.G. Date Engineering Geologist Senior Engineering Geologist Technical Review Unit Chief, Technical Review Unit (916) 341-5663 (916) 341-5684 Page 2 of 2