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-amp" <br /> ATTORNEY-CLIENT PRIVILEGE <br /> Introduction <br /> This document serves as a closure report for the property located at 1033 East Scott Avenue <br /> and 1020 West Hazelton, also known as the Santa Fe Railway Company Site in Stockton, <br /> California (the "Site"). In 1987, the Atchison, Topeka and Santa Fe Railway Company <br /> acquired the Site in a condemnation proceeding to develop a connection track between two <br /> perpendicular railroad tracks. Predevelopment activities included the discovery and removal <br /> of an underground vault and three underground, steel, single-walled, storage tanks from the <br /> Site. During the vault/tank removal, petroleum hydrocarbon-impacted soils were found <br /> beneath two of the tanks. <br /> A variety of environmental study activities have occurred at the Site. These include soil <br /> sampling and analysis, monitor well installation, quarterly groundwater sampling and <br /> analysis, partition-migration studies, and a risk assessment. These studies have all been <br /> submitted to the San Joaquin County Public Health Service (SJCPHS) and have been the <br /> focus of discussions at several meetings. The data and analysis of petroleum hydrocarbons <br /> support the closure of the Site with the hydrocarbons left in place. <br /> On August 11, 1993, a meeting was held with staff members from the SJCPHS in Stockton, <br /> California. The purpose of the meeting was to discuss the results of the risk assessment <br /> report, answer any questions, and determine the next course of action. At that meeting, <br /> technical issues relating to the intermittent reporting of hydrocarbons in groundwater at the <br /> Site in the micrograms per liter (µg/L) or parts per billion (ppb) range were discussed. <br /> SJCPHS requested a history of the groundwater sampling results and an analysis to <br /> determine if the random groundwater detects were Site-related. <br /> This report presents the analysis to support closure of the Site. Included in this letter are <br /> a summary of the risk assessment, a review of the results of groundwater sampling, an <br /> analysis using gas chromatographic results of soil and groundwater laboratory analyses, and <br /> partition studies. The data presented demonstrate that the chemicals detected in the <br /> groundwater below the Site are not Site-related and the Site can be closed with <br /> hydrocarbons in place without any significant environmental impact or risk of future impacts. <br /> Risk Assessment Summary <br /> In May, 1993, ChemRisk® submitted to SJCPHS a baseline risk assessment for the Site <br /> which assessed (1) the potential for chemical migration through soil to groundwater and (2) <br /> the magnitude of any potential Site-related exposures and potential health risks associated <br /> with current Site conditions. Using environmental fate and transport modeling, it was <br /> demonstrated that the petroleum hydrocarbons had only limited migration potential in Site <br /> soil. Over a 99-year period, tetradecane, used as a conservative surrogate chemical, <br /> migrated less than one foot. ChemRisk® concluded that the petroleum hydrocarbons will <br /> Q:\STAFFVa,LP\DELM.CLO 1 <br />