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The mean concentration and 90%UCL values for total lead data were less than 350 mg/kg. This suggests that the soil, if treated as a whole and sampled on a composite basis from stockpiles generated during construction activities,may not require Class I disposal and may be handled within the conditions of the variance. The excavated soil will likely not require soluble lead analysis by the WET as the mean and 90% UCL are less than 50 mg/kg, a level that triggers the WET analysis when considering soil disposal options. Even if WET analyses are conducted it is not likely that composite soil samples would contain soluble lead at concentrations greater than the STLC as the predicted soluble lead concentration and 90%UCL value for soluble lead by the WET are less than 5 mg/l. The composite soil profile for the project would likely have soluble lead concentrations less than the STLC and would not be considered a California hazardous waste. If management of the soil within the variance is required based on soluble lead concentrations, the statistical data indicate that the soil would be allowed to be re-used within condition 1 of the proposed variance, if the soil is excavated and treated as a whole (0 to 0.6 meters). This condition requires that the soil be used as fill beneath at least one foot of clean (non-hazardous) soil and five feet above the water table. 4.2 UST Investigation Results The geophysical surveys did not detect evidence of potential USTs within the areas surveyed at the northeast and northwest corners of the intersection. The geophysical surveys did detect an anomaly in the area surveyed at the southwest corner of the intersection. It was not known whether the anomaly was created by a UST or a utility vault associated with nearby underground utilities (Appendix D). The only constituents reported in the deeper soil samples included in the UST investigation were TPHd(960 mg/kg) in a soil sample collected from approximately 1.2 meters (4 feet)BGS within boring HP-1 and TPHmo (53.7 mg/kg) in a soil sample collected from approximately 1.2 meters (4 feet)BGS within boring HP-2. Additionally, organic lead was reported in a soil sample collected from approximately 7.9 meters (26 feet)BGS within boring HP-1 (Table 2). Organic lead, consisting of tetraethyl lead and/or tetramethyl lead,was used as a gasoline additive to raise octane ratings and lubricate soft metal valves. The reported organic lead concentration was 14 mg/kg. The reported organic lead concentration exceeds the EPA, Region 9, residential soil Preliminary Remediation Goal (PRG) of 0.0061 mg/kg (EPA, 2000). SncDP-N:IruncjpllProjecisl8P8?11641Reportlll0 Austin repon.doc 4-5 5121101