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No soil samples were reported to contain total lead concentrations that exceed the TTLC value of 1,000 mg/kg for lead. Soil samples collected from borings 5, 12, 13, 14, 17, 23, 24, 36, and 40 were reported to contain soluble lead at concentrations in excess of the STLC of 5 mg/l by WET analysis. Soil samples reported to contain total lead exceeding the TTLC and soluble lead exceeding the STLC would be considered a California-Hazardous waste, should the soil become a waste. A soil sample from boring 37 was reported to contain total lead at a concentration in excess of 350 mg/kg. No soil samples were analyzed by the TCLP. The California Environmental Protection Agency, Department of Toxic Substances Control (DTSC), granted Caltrans a variance for soil considered hazardous due to the presence of elevated lead concentrations (DTSC, 2000). The variance allows Caltrans to re-use lead- contaminated soil within Caltrans right-of-way in the roadway corridor boundaries under certain conditions if the soil is considered a non-RCRA waste. In accordance with the variance and AB 2784 Section 25157.8, the following conditions apply to Caltrans'reuse and management of soil impacted by aerially deposited lead as fill material for construction and maintenance operations (DTSC, 2000): 1) As fill beneath at least one foot of clean (non-hazardous) soil and five feet above the water table if the soluble lead concentration reported by the DI WET analysis is less then 0.5 mg/1 and the total lead concentration is less than 350 mg/kg. This condition applies only if the soil is not a RCRA waste. 2) As fill beneath a pavement structure designated to protect the soil from water infiltration and five feet above the water table if the soluble lead concentration reported by DI WET analysis is greater then 0.5 mg/l but less then 50 mg/l, and the total lead concentration is less than 350 mg/kg. This condition applies only if the soil is not a RCRA waste. 3) Lead-contaminated soil with a pH below 5 shall only be used as fill beneath the paved portion of the roadway. This conditions applies only if the soil is not a RCRA waste. No TCLP analyses were conducted. Therefore, evaluation of whether the soil would be considered a RCRA-hazardous waste and whether the soil would be excluded from the variance based on a Federal waste classification was not performed. 4.1.2 Lead Data Statistical Analysis To further evaluate the applicability of the DTSC variance (DTSC, 2000), IT conducted a statistical evaluation of lead analytical data for this project at the request of Caltrans. The statistical evaluation was conducted in general accordance with guidance provided in SW-846, SncDP-N:IrnncjpllProjectsl8A8L?641Reporill?0 Austin report.doc 4-2 5111101