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Site Background Information: Chapin Brothers Investments, Inc. <br /> Page 12 of 19 <br /> GROUND WATER REMEDIATION <br /> Based on an EHD office meeting conducted on 05 April 2000 the EHD and the Central Valley <br /> Regional Water Quality Control Board(CVRWQCB) verbally agreed on the use of ground water <br /> extraction and treatment to mitigate the site. <br /> At that meeting the profession geologist (Nuel Henderson) requested the agency review the <br /> assessment remedation case for closure based on the following: <br /> • Age of release <br /> -Degradation of gasoline components <br /> -Limited migration <br /> • Dissolved hydrocarbon plume well defined <br /> • Lack of sensitive water receptors <br /> Closest water well>2,000 feet from site <br /> • EC high, (1,600 micro s/cm MW3 and MW5)probably brackish water <br /> • Proximity to delta limits potential for installation of a water well in the area <br /> • Limited MTBE distribution and low concentrations <br /> • Remediation has been conducted,hydrocarbon mass has been reduced <br /> • Technologic difficulty of additional significant hydrocarbon mass reduction <br /> As note above an SVE/IAS system has been installed and operated at the site to remediate <br /> hydrocarbon-impacted soil and ground water. Over the course of the remediation, rising ground <br /> water elevation has submerged a significant portion of contaminated soil below the ground water <br /> table and capillary fringe. Under this condition,hydrocarbon-impacted ground water has remained <br /> and the overall influence of the IAS system has demonstrated diminishing effectiveness at reduction <br /> of dissolved hydrocarbons.Areas in the eastern portion of the site and at the northwest corner of the <br /> site have not demonstrated a sustained reduction of dissolved hydrocarbons. Ground water has <br /> remained impacted. <br /> The implications from the set of March 2001 aquifer ground water extraction tests were the <br /> following. The ground water table occurred within the screened interval of the well and the most <br /> likely source of the extracted ground water was from the highly permeable sand,encountered from <br /> 20 feet to 30 feet bsg. <br /> Advanced GeoEnvironmental,Inc. <br />