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2.0 Site Investigations, Monitoring, and Remediation <br /> The Stockton Service Center site has been the subject of several investigations, <br /> studies, monitoring, and remedial designs since the USTs were removed in 1987 and <br /> ' 1989. Three separate soil and groundwater investigations have been performed at <br /> the site by three consultants Groundwater monitoring has been implemented at the <br /> ' site since 1989 A remedial action feasibility study and two remedial action plans <br /> were prepared The investigations, monitoring,feasibility study, and remedial designs <br /> are summarized in the following sections. <br /> 2.1 Investigations <br /> ' In 1987 the District removed the first of three USTs, a 1,000 gallon leaded <br /> gasoline UST, from the Stockton Service Center Petroleum hydrocarbons In excess <br /> ' of detection limits were detected in the soil beneath the east end of the tank A soil <br /> and groundwater assessment performed by Kleinfelder, Inc (Kleinfelder)in May and <br /> October 1989 revealed petroleum hydrocarbons in excess of detection limits in soil <br /> and groundwater in the vicinity of the former tank location This assessment <br /> ' included the installation of three groundwater monitoring wells, MW-1, MW-2, and <br /> MW-3 and four soil borings, B-1, B-2, B-3, and B-4 Benzene, toluene, ethylbenzene, <br /> and xylenes (BTEX) and total petroleum hydrocarbons (TPH) constituents were <br /> ' detected in boring B-1, downgradient of the former UST location, and in boring B-2, <br /> near the former UST location BTEX and TPH were also detected in MW-1, <br /> ' downgradient of the former UST. Organic lead was not detected in any of the soil <br /> samples The water samples were not analyzed for lead. Petroleum hydrocarbons <br /> were not detected in samples from the other bonngs and monitoring wells <br /> Groundwater was determined to flow towards the southwest Kleinfelder <br /> recommended removing the two remaining USTs, installing three to five additional <br /> wells southwest (downgradient) of the USTs, and initiating quarterly groundwater <br /> monitoring The results of the Kleinfelder assessment are summarized in Appendix <br /> ' C, Tables C-1 and C-2 <br /> In September 1989, the District removed the two remaining USTs These tanks <br /> were reported to contain unleaded gasoline and leaded gasoline No indications of <br /> leakage from these tanks were observed and no petroleum hydrocarbons in excess <br /> of detection limits were found in the soil beneath the tanks These two USTs were <br /> replaced with two aboveground tanks <br /> 96117 East Bay Municipal Utility District <br /> ' 40429700 fcr 9 Final Closure Report <br />