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j 2.0 Project History An Initial Site Assessment was completed for the Tracy Maintenance Station (Geocon, 2001) and included a site history. In April 1988, one wast oil underground storage tank (UST) was removed from the site. No further documentation reg ding the waste oil UST removal activities was available. In September 1996, one steel 7,600-liter (2,000-gallon) gasoline UST and one steel 7,600-liter (2,000-gallon) diesel fuel UST were removed from the site. The USTs were reportedly in good condition and stains or holes were not noted. Laboratory results indicated that total petroleum hydrocarbons as gasoline (TPHg), benzene, toluene, ethylbenzene, total xylenes (BTEX) and methyl tert-butyl ether(MTBE) were not detected in soil samples collected from the bottom of the former gasoline UST excavation. Total petroleum hydrocarbons as diesel (TPHd) was not detected in soil samples collected from the b ttom of the former diesel UST excavation. Total lead concentrations ranging from 1.5 to 9.2 mil igrams per kilogram (mg/kg) were detected ' in soil samples collected from the former gas ine UST excavation. Groundwater was encountered at approximately 3.3 m (I1 feet) below ground surface (BGS) during UST removal activities. TPHg, TPHd, BTEX, and total lead were not detected in a grab groundwater sample collected from the excavation. MTBE was detect d in the grab groundwater sample at a concentration of 31 micrograms per liter (µg/l)- The reported presence of MTBE was based on ' EPA Test Method 8020 data and may represent a false positive. The San Joaquin County Environmental Health Division (SJCEHD) issued a `no further action' letter in January 1997 u (misdated January 3, 1996) for the fuel UST removals. The SJCEHD issued a `no further action' letter dated January 3, 1996 (sic 1997). t + -IISACRFPIIGOMMOMSecDP12002tPRJVAJ8Y8318354442ab.dac 2-1