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Metal Concentrations in ppm <br /> Minimum Maximum !LC-L95 <br /> Copper 34 908 264 <br /> Lead 11 58 73 <br /> ' Chromium 24 31 35 <br /> Hex Chromium <0.05 <0.05 Not Calculated <br /> 1 Soluble Metal Concentrations <br /> Concentrations of soluble copper using the DI-WET test on the three samples with the highest <br /> levels of total copper were between 0.08 and 0.12 ppm. This equates to solubilities between <br /> ' 0.09% - 0.8% of total copper. The concentrations of soluble copper and soluble lead using the <br /> STLC test were beneath the respective criteria for hazardous waste. <br /> 5.0 RISK/HAZARD RISK/HAZARDEVALUATION <br /> The Human Health Risk Evaluation was conducted in a manner consistent with the procedures set <br /> forth in the Preliminary Endangerment Assessment Guidance Manual ("PEA" - DTSC, 1994). <br /> 5.1 Identification of Constituents of Potential Concern <br /> Based upon the initial sampling conducted by San Joaquin County and from a knowledge of the <br /> materials used in the site operation, the primary Constituent of Potential Concern (COPC) was <br /> identified as copper. Since somewhat elevated concentrations of lead and chromium were also <br /> present in the initial soil sample, these metals were also treated as COPCs. Hexavalent <br /> chromium was not detected in any sample. However, because of it's carcinogenic properties and <br /> to take a very conservative approach to the risk evaluation it was also treated as a COPC. <br /> 5.2 Toxicity/Cancer Potency of COPCs <br /> ' The relative non-cancer toxicity of chemical compounds is quantified by the Reference Dose <br /> ("Rfd") which is expressed in units of milligrams per kilogram body weight per day (mg/kg-d). <br /> The relative cancer potency of carcinogens is quantified by the Cancer Slope Factor ("SF") in <br /> units of (mg/kg-d)-l. When combined with human chemical intake values these units allow for <br /> the quantification of the risk of toxic effects and of contracting cancer. Slope factors and <br /> reference doses used in the risk evaluation were obtained from the following authorities: <br /> ' Of the COPCs, only hexavalent chromium is a known carcinogen. Published Slope Factors for <br /> both the inhalation (subscript "i") and oral (subscript "o") exposure routes are available. The <br /> ' Slope Factors utilized in the evaluation are from California Cancer Potency Factors Update <br /> (OEHHA, 11/94). <br /> 6 <br />