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BP#172 May 2015 <br /> 7647 Pacific Avenue, Stockton <br /> Claim No: 2156 <br /> designated beneficial uses of the affected shallow groundwater are not threatened, and it is <br /> highly unlikely that they will be, considering these factors in the context of the site setting. <br /> Rationale for Closure under the Policy <br /> • General Criteria: The case meets all eight Policy general criteria. <br /> • Groundwater Specific Criteria: The case does not meet Policy criteria because the <br /> groundwater plume is not defined to the northeast and the maximum dissolved <br /> concentration of benzene is greater than 3,000 micrograms per liter(pg/L). <br /> • Vapor Intrusion to Indoor Air: The case meets Policy Criterion 2a by Scenario 1. There are <br /> high concentrations of petroleum hydrocarbons in the groundwater. The minimum depth to <br /> groundwater beneath the foundation of existing or potential buildings is greater than 30 feet, <br /> overlain by soil containing less than 100 milligrams per kilogram (mg/kg) of TPH. <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 revie ed, a professional <br /> assessment of site-specific risk from potential exposure to residual soil contamination was <br /> completed by Fund staff. The results of the assessment found that maximum <br /> concentrations of petroleum constituents remaining in soil will have no significant risk of <br /> adversely affecting human health. Approximately 1,500 cubic yards of impacted soil were <br /> removed and disposed offsite in 1995. In addition, an unknown volume of contaminated soil <br /> was excavated to a depth of 16 feet bgs and removed in December 2007. The Site is paved <br /> and accidental exposure to site soils is prevented. Therefore, the pathway is incomplete. <br /> Any construction crew performing subsurface work will be prepared to deal appropriately <br /> with environmental hazards anticipated or encountered in their normal daily work. The <br /> presence of residual contamination should be taken into account when issuing and <br /> executing excavation or building or other permits at the Site, i cluding but not limited to the <br /> inclusion of a Competent Person in the work crew. <br /> Objections to Closure and Responses <br /> According to the Path to Closure page in GeoTracker, finalized on September 19, 2014, the <br /> County staff objects to UST case closure because: <br /> • Secondary source remains. <br /> RESPONSE: Secondary source as defined by the Policy was removed by excavation and <br /> active remediation. Approximately 1,500 cubic yards of impacted soil were removed and <br /> disposed offsite in 1995. In addition, an unknown volume of contaminated soil was <br /> excavated to a depth of 16 feet bgs and removed in December 2007. Dual phase extraction <br /> was conducted between April 2001 and March 2009, which removed 210,156 pounds of <br /> TPHg vapor and 582,804 gallons of contaminated groundwater. Ozone sparging was <br /> conducted in 2009. Active remediation has not been conducted for the past six years. <br /> • The case does not meet Policy groundwater criteria. <br /> RESPONSE: We concur. The case does not meet Policy criteria because the groundwater <br /> plume is not defined to the northeast and the maximum dissolved concentration of benzene <br /> is greater than 3,000 pg/L. <br /> • The case does not meet Policy vapor criteria. <br /> RESPONSE: The case meets Policy Criterion 2a by Scenario 1. There are high <br /> concentrations of petroleum hydrocarbons in the groundwater. The minimum depth to <br /> groundwater beneath the foundation of existing or potential buildings is greater than 30 feet, <br /> overlain by soil containing less than 100 mg/kg of TPH. <br /> Page 2 of 3 <br />