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were detected in the soil beneath the east end of the tank A soil and groundwater <br /> assessment performed by Kleinfelder, Inc (Kleinfelder) in May and October 1989 <br /> ' revealed petroleum hydrocarbons in excess of detection limits in soil and groundwater <br /> in the vicinity of the former tank location This assessment included the installation <br /> of three groundwater monitoring wells, MW-1, MW-2, and MW-3 and four soil <br /> ' borings, B-1, B-2, B-3, and B-4 Benzene, toluene, ethylbenzene, and xylenes (BTEX) <br /> and total petroleum hydrocarbons (TPH) constituents were detected in boring B-1, <br /> ' downgradient of the former UST location, and in boring B-2, near the former UST <br /> location BTEX and TPH were also detected in MW-1, downgradient of the former <br /> UST Organic lead was not detected in any of the soil samples The water samples <br /> were not analyzed for lead Petroleum hydrocarbons were not detected in samples <br /> from the other borings and monitoring wells Groundwater was determined to flow <br /> ' towards the southwest In September 1989, Kleinfelder recommended removal of the <br /> two remaining USTs In their assessment report dated November 17, 1989, <br /> ' Kleinfelder recommended that three to five additional wells be installed southwest <br /> (downgradient) of the UST and quarterly monitoring be conducted The results of <br /> this assessment are summarized in Appendix A on Table A-1 and the sample <br /> locations are shown on Figure 3 <br /> In September 1989, following the initial phase of the Kleinfelder assessment, <br /> the District removed the two remaining USTs These tanks were reported to contain <br /> unleaded gasoline and leaded gasoline No indications of leakage from these tanks <br /> ' were observed and no petroleum hydrocarbons in excess of detection limits were <br /> found in the soil beneath the tanks These two USTs were replaced with two above <br /> ' ground tanks <br /> In February 1991, Roy F Weston, Inc (Weston) performed an additional <br /> ' assessment of the site that included drilling four soil borings and completing each as <br /> monitoring wells (MW-4, MW-5, MW-6, and MW-7) Low levels of toluene and Iead <br /> were detected in soil samples from all four borings while xylenes were detected in soil <br /> ' samples from three of the four borings Benzene, xylenes, and total petroleum <br /> hydrocarbons in the gasoline range (TPH-g) were detected in MW-1 No petroleum <br /> ' hydrocarbons in excess of detection limits were found in the groundwater from any <br /> other wells <br /> Weston performed quarterly monitoring of the groundwater monitoring wells <br /> for the second and third quarters of 1992 and the first quarter of 1993 Benzene, <br /> toluene, xylenes, and TPH-g were detected in only MW-1 during these sampling <br /> ' 93R22 Fast Bay Municipal Utility District <br /> 40429500 asa 3 Stockton Svc Ctr -Site Assessment/Rcmcdial Options <br /> i <br />