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LFR Levine-Fricke The environmental risks,potential exposures, and potential effects of exposures will be discussed with greater detail when the Site is characterized during the comprehensive RI/FS to be completed. 4.1 Extent of Contamination Surficial soil within the burn areas at the Site likely contains elevated concentrations of some metals(i.e. arsenic and zinc)and pyrolytic oil within burn areas-1, -2, -3, and- 17. Figure 2 shows the location and lateral extent of the 34 burn piles at the Site and location of where pyrolytic oil was noted during the fire extinguishing event by CIWMB personnel. Based on the data collected to date, deeper soil samples (collected at 6 feet bgs or deeper)did not contain elevated metals concentrations and do not appear to have been affected by the tire fire. Comparison of the analytical data with regional background concentrations indicate that concentrations of antimony, arsenic, cadmium, cobalt, copper, iron, lead, manganese, and zinc in surface soil samples exceeded regional background concentrations. Arsenic concentrations in a few of the deeper samples (6 to 8 feet and 14 to 16 feet bgs) collected exceeded the regional background, but not the site background, concentration for arsenic. Table 1 provides a summary of the minimum and maximum values of metals concentrations detected in soil samples, hazardous waste characterization action level concentrations (including TTLC, STLC, and toxicity characteristic leaching procedure [TCLP] concentrations), and reference background concentrations that were reported during the preliminary RI/FS. Based on the data in Table 1, there are four metals (arsenic, copper, lead, and zinc) detected in soil samples collected during the preliminary RI/FS that based on their potential to leach classify the soil as a Class I non-RCRA waste. Zinc is the only metal that was detected at a total concentration(>30,000 mg/kg) over the TTLC. Based on the data, zinc is the primary contaminant of concern at the project site. The source of zinc in the burn pile areas is from the burnt radial wires within the tires. Criteria used to classify soil for waste disposal is discussed in Section 7.4.5 of this RAP. 4.2 Potential Migration and Exposure Pathways This section provides an overview of the potential migration and exposure pathways at the Site. A more in depth evaluation will be conducted during the comprehensive RI/FS to be conducted following interim source removal activities. The potential migration pathways for metals or components of pyrolytic oil(VOC or SVOCs)in soil at the Site include volatilization, erosion via wind or surface water, dispersion into outdoor air via wind, and leaching and migration to groundwater. Once in groundwater, contaminants will generally migrate with groundwater in the direction of groundwater flow. Page 6 Final_RAP_Tracy_9.18.03(final).doc