SITE INFORMATION AND CORRESPONDENCE FILE 2

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• � v Fernando Place November 2013 1201 South Center Street, Stockton Claim No: 12186 Rationale for Closure under the Policy • General Criteria: The case meets all eight Policy general criteria. • Groundwater Specific Criteria: The case does not meet Policy criteria because the contaminant plume that exceeds water quality objectives is undefined and because maximum benzene concentrations in groundwater exceed 1,000 pg/L. • Vapor Intrusion to Indoor Air: The case meets Policy Criterion 2a by Scenario 4 with no bioattenuation zone. The maximum benzene, ethylbenzene, and naphthalene concentrations in soil gas are less than 85 pg/m3, 1,100 pg/m3, and 93 pg/m3, respectively at a depth of five feet. These levels meet the Residential soil gas criteria (Advanced GeoEnvironmental (AGE), 2010). • Direct Contact and Outdoor Air Exposure: The case meets Policy Criterion 3a. Maximum concentrations in soil are less than those in Policy Table 1 for Commercial/Industrial use, and the concentration limits for a Utility Worker are not exceeded. There are no soil sample results in the case record for naphthalene. However, the relative concentration of naphthalene in soil can be conservatively estimated using the published relative concentrations of naphthalene and benzene in gasoline. Taken from Potter and Simmons (1998), gasoline mixtures contain approximately 2 percent benzene and 0.25 percent naphthalene. Therefore, benzene can be directly substituted for naphthalene concentrations with a safety factor of eight. Benzene concentrations from the Site are below the naphthalene thresholds in Policy Table 1. Therefore, the estimated naphthalene concentrations meet the thresholds in Table 1 and the Policy criteria for direct contact by a factor of eight. It is highly unlikely that naphthalene concentrations in the soil, if any, exceed the threshold. Recommendation The Fund recommends that the County direct the Responsible Party to: • Define the extent of the groundwater plume. • Implement cost effective soil and groundwater remediation that will significantly reduce contaminant mass in the source area. The Fund is skeptical the selected remediation technology will accomplish this task. /1 1,2 1� 3 Kiift Larson, P.G. Date Kobert Trommer, C.H.G. Date Engineering Geologist Senior Engineering Geologist Technical Review Unit Chief, Technical Review Unit (916) 341-5663 (916) 341-5684 i Page 2 of 14