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ATC SITE SAFETY PLAN <br /> FACILITY BACKGROUND <br /> Prior to July 1984, one 550-gallon waste oil UST, identified as Tank #4, was emptied of <br /> product, filled with sand, and capped with concrete. In November 1986, one 1,000-gallon <br /> regular gasoline UST, identified as Tank #3, was removed and disposed of. Soil sample <br /> collected during the removal of Tank #3 contained elevated concentrations of petroleum <br /> hydrocarbons. In May 1989, one 1,000-gallon unleaded UST, identified as Tank #1 was <br /> filled with five cubic yards of concrete. Currently two USTs, identified as Tanks #2 and #5, <br /> remain in place and are in operation. <br /> On June 18, 1998, an ATC geologist supervised the advancement of two soil borings (SBI <br /> and SB2) to 86.5 feet below ground surface (bgs) to assess current subsurface conditions at <br /> the site. Petroleum hydrocarbon constituents were detected in soil samples collected from <br /> borings SBI and SB2. The highest reported constituent concentrations were observed in <br /> soil samples collected at 25.5 feet bgs in each of the borings. The highest concentrations of <br /> petroleum constituents at this depth were observed in SBI and include TPHg (9,500 <br /> mg/kg), toluene (65 mg/kg), ethyl benzene (82 mg/kg), and xylenes (470 mg/kg). The <br /> petroleum hydrocarbons appear to attenuate rapidly with depth as indicated greatest by <br /> soil samples from SBI at 45.5 feet bgs and S112 at 55.5 feet bgs which contained only trace <br /> amounts of petroleum hydrocarbons or none above the laboratory detection limits. Total <br /> lead was detected at 5.5 mg/kg from the soil sample collected form SBI at 25.5 feet bgs. <br /> Neither benzene, fuel oxygenat-eadditives, or VOCs were detected above laboratorymethod <br /> detection limits in any`oT the soil samples analyzed. <br /> Petroleum hydrocarbon constituents, including TPHg and BTEX, were detected in <br /> groundwater samples collected from borings SB1 and S112. Only benzene, which was <br /> reported at concentrations of 7.6 ug/l and 12 ug/l, respectively, exceeded California's <br /> Maximum Contaminant Level (MCL) for drinking water. <br /> In correspondence dated October 9, 1998, PHD/EHD requested additional work be <br /> performed at the project site. <br /> PAGE <br />