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Executive Summary IT Corporation (IT) conducted a lead in soil investigation along State Route 120 (SR 120) in San Joaquin County, California. Work was conducted within the shoulders of Austin Road and SR 120 between post mile SJ-120 PM 6.7/7.0. The investigation was conducted to evaluate the presence and concentration of lead in shallow soil and petroleum hydrocarbons within groundwater in the work area prior to the implementation of improvement activities proposed by Caltrans. Lead was reported in soil samples collected from the site. The source for the lead is not known, however, it is thought to be related to accumulation of dust and debris containing lead from leaded gasoline emissions. Lead concentrations were compared to Total Threshold Limit Concentration (TTLC) and Soluble Threshold Limit Concentration (STLC) values to evaluate whether the soil would be considered a hazardous waste, should it become a waste. Soil samples from various portions of the site were reported to contain lead at concentrations that exceeded the STLC. One soil sample was reported to contain lead at a concentration in excess of 350 milligrams per kilogram (mg/kg), a level requiring waste disposal in a Class I facility. Statistical evaluation of the data found that the mean concentration of total lead in the entire data set was 36.0 mg/kg with a corresponding 90%Upper Confidence Level (UCL)value of 44.8 mg/kg. An expected soluble lead concentration was obtained from regression analysis (model forced through the origin) developed from the total/WET and total/DIWET soluble lead data. The soluble lead concentration for WET data corresponding to the total lead 90%UCL is 0.899 milligrams per liter(mg/1). The soluble lead concentration for DIWET data corresponding to the total lead 90%UCL is 0.128 mg/l. To compare with predicted soluble lead concentrations, 90% UCL concentrations for the WET and DIWET data set were calculated. The 90%UCL value for the WET and DIWET data are 5.11 and 0.463 mg/l, respectively. These calculations were conducted on data that are skewed to higher values by the sample selection criteria and therefore result in higher concentration values than the predicted soluble lead concentrations. The California Environmental Protection Agency, Department of Toxic Substances Control (DTSC), issued Caltrans a variance for soil considered hazardous due to the presence of elevated lead concentrations. The variance allows Caltrans to re-use lead-contaminated soil within Caltrans right-of-way in the roadway corridor boundaries under certain conditions. SncDP-N.IrancjpllPmjectsl8218111641Report1120Austin report.doc ES-1 .5121101