SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

I Guardino — Crawford Company February 2015 517 West Fremont Street, Stockton Claim No : 14349 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 1 . The contaminant plume that exceeds water quality objectives is less than 100 feet in length. There is no free product. The nearest water supply well or surface water body is greater than 250 feet from the defined plume boundary. • Vapor Intrusion to Indoor Air: The case meets Policy Criterion 2a by Scenario 3a . The maximum benzene concentration in groundwater is less than 100 micrograms per liter (pg/L). The minimum depth to groundwater is greater than 5 feet, overlain by soil containing less than 100 milligrams per kilogram (mg/kg) of TPH. • 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 used as a surrogate 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 . Objections to Closure and Responses According to the LTCP Checklist in GeoTracker, finalized on April 30, 2014, the County objects to UST case closure because: • Secondary source has not been removed to the extent practicable because SVE and IAS systems have been installed but no report of operation yet received . RESPONSE: The results of SVE and IAS operations are now available, and have demonstrated the remediation has been effective in reducing the benzene plume. • The case does not meet Policy groundwater criteria . RESPONSE: The case now meets Policy Criterion 1 by Class 1 . • The case does not meet Policy vapor criteria. RESPONSE : The case now meets Policy Criterion 2a by Scenario 3a . Determination The Fund Manager has notified the tank owners or operators and reviewed the case history of their tank case . The Fund Manager determines that closure of the tank case is appropriate based upon that review. The Fund Manager has prepared this review summary report summarizing the reasons for this determination, provided the Review Summary Report to the applicable Regional Water Board and Local Oversight Agency Program, as appropriate, with an opportunity for comment on the Review Summary Report, Page 2 of 3