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MCLs Therefore, the predicted impact of total xylenes and ethylbenzene to groundwater is <br /> negligible For reference, model input and output files are contained in Appendices C and D <br />` respectively <br />' 9.2.1.2 Location !l, Sidewalk Area <br /> No detectable volatile petroleum hydrocarbon concentrations were encountered in any of the <br /> samples collected during tank removal or subsequent verification sampling events Therefore, <br /> no modeling for xylenes and ethyl benzene impacts to groundwater could be performed <br /> 9.2.2 Diesel <br /> No California MCL currently exists for diesel The Federal EPA SNARL is 100 ppb for <br /> exposure of 10 days or less (Marshack, 1991). <br /> 9.2.2.1 Location 1, Basement Area <br /> At Location I, the maximum predicted diesel concentration in the groundwater at Location I <br /> will be 44 ppb in 50 years This is higher than any predicted concentration for years 1 <br /> through 49 This concentration is below the Federal EPA SNARL for diesel Therefore, it is <br /> very unlikely that the diesel at Location I will cause any significant impact to groundwater <br /> 9.2.2.2 Location Il, Sidewalk Area <br /> At Location II, the maximum predicted diesel concentration in the groundwater at Location II <br /> will be 0 6 ppb in 50 years This is higher than any predicted concentration for years i <br /> through 49 This concentration is below the Federal EPA SNARL for diesel Therefore, it is <br /> very unlikely that the diesel at Location II will cause any significant impact to groundwater <br /> 10.0 Conclusion <br /> The Pacific Bell site originally contained five underground storage tanks containing diesel <br /> fuel Two USTs (300 gallons and 550 gallons) located beneath the basement floor were <br /> abandoned in place in May 1990 Three 25,000-gallon diesel USTs were removed from <br /> beneath the Lindsay Street sidewalk in November 1993. Verification soil samples from both <br /> sites revealed residual diesel fuel upon analysis The results of remediation activities to date <br /> have been primary source removal (tank removal or abandonment) and disposal of <br /> approximately 160 tons of impacted soil (sidewalk area overexcavation) <br /> MZ/04-06-95/UST/95-0089 16 <br /> I <br /> I <br /> I <br />