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Chevron #9-8632 September 2014 525 West Grant Line Road , Tracy N Claim No: 9662 groundwater are not threatened, and it is highly unlikely that they will be, considering these factors d in the context of the site setting . Rationale for Closure under the Policy • General Criteria: The case does meet all eight Policy general criteria. It is not conclusive whether secondary sources have been removed to the extent practicable in the former gasoline UST and dispenser areas. • Groundwater Specific Criteria: The case meets Policy Criterion 1 by Class 1 . The contaminant plume that exceeds water quality objectives is less than 100 feet in length . There is no free j product. The nearest water supply well or surface water body is greater than 250 feet from the 1 defined plume boundary. • Vapor Intrusion to Indoor Air: This case meets Policy Criterion 2b. Although no document titled " Risk Assessment" was found in the files reviewed , a professional assessment of site- specific risk from potential exposure to petroleum constituents was performed by Fund staff. The assessment found that there is no significant risk of petroleum vapors adversely affecting human health. Although two soil vapor sample results in 2010 did not meet the Policy criteria, the sampling locations were in open areas. The only structure at the Site is a mobile office trailer with crawl space below the structures floor. Soil vapor intrusion, if any, would dissipate before reaching indoor space. Therefore, the pathway is incomplete. • Direct Contact and Outdoor Air Exposure: This case does not meet Policy criteria because historically several soil sampling results from six feet below surface (likely above groundwater table) did not meet Policy Table 1 , and current shallow soil conditions in the former gasoline UST and dispenser areas are unknown. Objections to Closure and Responses According to the Path to Closure page in GeoTracker, finalized on September 2, 2014, the County objects to UST case closure because: • Secondary source remains. RESPONSE: We agree it is not conclusive whether secondary sources have been removed to the extent practicable in the former gasoline UST and dispenser areas. • The case does not meet Policy vapor criteria . RESPONSE: This case meets Policy Criterion 2b. • Thecasedoesnot-meet-Policy- irect contact criteria. RESPONSE: We agree. Recommendation The Fund recommends that the County direct the responsible party to conduct a shallow soil assessment at the Site to evaluate the current conditions and implement focused remediation if warranted . ICrarson, P. G. Date RobertTrommer, G.H.G. Date Engineering Geologist Senior Engineering Geologist Technical Review Unit Chief, Technical Review Unit (916) 341 -5663 (916) 341 -5684 I I Page 2 of 2 I�