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QUARTERLY SUMMARY REPORT <br /> Second Quarter 2000 <br /> (April -June) <br /> FORMER UNOCAL SERVICE STATION 5098 <br /> 5606 Pacific Avenue <br /> Stockton, California <br /> City/County ID: City of Stockton. San Joaquin County <br /> Lead Agency: San Joaquin County Department of Public Health Services <br /> BACKGROUND <br /> The former Unocal service station site is presently occupied by Washington Mutual Bank and Icon <br /> Business Solutions. Properties in the vicinity of the site are occupied by commercial developments and <br /> include a former Montgomery Ward Service Station located south of the site. An irrigation well is also <br /> located south of the subject site on the San Joaquin Delta College (Delta) campus. This well reportedly <br /> operates between May and October during the night and early morning at an extraction rate of up to <br /> approximately 240,000 gallons per day. Environmental work at the site was initiated in 1985 when <br /> Unocal concluded retail operations and removed two 10,000-gallon fuel underground storage tanks <br /> (USTs), one used-oil UST, and associated piping and dispensers. Environmental work completed at the <br /> site has included the following: <br /> Drilling of at least 19 soil borings; <br /> Excavation of approximately 6,000 cubic yards of hydrocarbon impacted soil to approximately <br /> 53 feet below ground surface (bgs) from the site; <br /> Installation of seven vapor wells (unknown designation), 13 on-site groundwater monitoring <br /> wells (RWI, Wl through W5, MWl through MW5, MW7, and MW8), and 10 off-site <br /> groundwater monitoring wells (MW6 and MW9 through MW17); <br /> Destruction of the vapor extraction wells during soil excavation and destruction of wells WI, <br /> W2, MWl, MW2, MW7, MW8, and RWl (wells W3 through W5, MW3 through MW5, and <br /> MW9 could not be located); <br /> • Completion of a well search with the California Department of Water Resources (DWR) which <br /> identified approximately 40 wells within one mile of the site; <br /> Completion of a hydrogeologic investigation of groundwater conditions beneath and in the <br /> vicinity of the site; <br /> Drilling of soil borings Bl, B2, and Hydropunch boring HPl; <br /> Installation of groundwater monitoring wells MW10A, MW14A, MW18, MW19S, MW19D, <br /> MW21S, MW21D, MW22S, and MW22D; and, <br /> Ongoing quarterly joint groundwater monitoring and sampling with adjacent Montgomery <br /> Wards site. <br /> During first quarter 2000, the San Joaquin County Department of Public Health Services listed <br /> the Unocal and Montgomery Ward properties as part of a commingled plume. <br /> 2279ao.2QS <br />