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' Updated Site Conceptual Model and First Quarter 2002 Monitoring and Remediation Report Cleanup and Abatement Order No 5-00-707 EAI Project No 1232 i 1.0 INTRODUCTION ' This document constitutes an updated Site Conceptual Model (SCM) and First Quarter 2002 Monitoring and Remediation Report for the former Montgomery Ward, LLC (Wards) site ' located at 5400 Pacific Avenue and the former Union Oil Company of California (Unocal) site located at 5606 Pacific Avenue, Stockton, California (see Figure 1) Ground water monitoring was conducted pursuant to requirements of Cleanup and Abatement Order No 5-00-707, issued ' to Wards, Unocal, Surry California Limited Partnership, and Stone Brothers and Associated General Partnership on September 8, 2000, by the California Regional Water Quality Control Board, Central Valley Region (RWQCB) (see Section l 1 4) Environmental Audit, Inc (EAI) ' was retained by Unocal to complete this report This report was prepared pursuant to the CAO and a RWQCB letter for this matter dated ' February 8, 2002 1.1 Background ' I 1 I Wards Site ' Wards formerly operated an auto service center at 5400 Pacific Avenue, Stockton, California (see Figure 2) Between 1986 and 1988, Wards removed one waste oil UST, four bulk oil USTs, and two gasoline USTs from the site Numerous investigations of the Wards site were conducted and a remedial system (air sparging coupled with vapor extraction) was installed to address the remediation of petroleum hydrocarbons present in soil and ground water beneath the Wards site The remedial system was put into full operation in November 1999, and was in operation until December 2000 when the auto service center and remedial system were shut down due to Wards filing bankruptcy During its operation, the Wards remedial system removed approximately 8,000 pounds of hydrocarbons ' Ground water monitoring at the Wards site has been conducted since 1993 Ground water monitoring activities for the Wards site and the Unocal site, for the most part, were coordinated ' by the various consultants representing the two entities and conducted simultaneously Table 1 summarizes the historical ground water testing results for the Wards and Unocal sites ' 1 1 2 Unocal Site The property located at 5606 Pacific Avenue contained a gasoline station between approximately 1955 and 1985 (see Figure 2) In 1985, the station was closed and the USTs 'r removed After completing investigations of the site, Unocal in 1988 excavated approximately ' 6,000 cubic yards of soil from the site The excavated soil was aerated, and based on the analytical testing results associated with the aerated soil, 5,800 cubic yards of the aerated soil was reused on-site as fill, and 200 cubic yards transported off-site for disposal On August 25, ' 1989, the RWQCB issued a letter for the Unocal site confirming that the soil contamination at the site has been adequately cleaned up, but, that the extent of ground water impact has yet to be defined ' -1- BHM 1232R0231 ENVIRONMENTAL A UDIT, INC