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KLEINFELDER <br /> For potential disposal purposes the metal results were also compared to the Total <br /> Threshold Limit Concentration (TTLC) from CCR as a Regulated Level for classification <br /> of the metals as a hazardous waste per California Code of Regulations 22CCR <br /> §66261.24. A Soluble Threshold Limit Concentration (STLC) is also used to evaluate <br /> hazardous waste classification for disposal purposes. Lead values detected at the site <br /> were also compared to Section 25157.8 of the California Health and Safety Code <br /> (CH&SC). <br /> 6.1 METAL RESULTS <br /> Metals were detected in the Dry Well, Race Track Areas and Debris Areas. <br /> 6.1.1. Dry Well Areas <br /> Six of ten metals Including <br /> arsenic, barium, cadmium, chromium, lead and selenium <br /> were detect in soil sample collected adjacent to 5 reported dry wells. Five of these <br /> metals were found to be below Residential PRGs and OEHHA health risk numbers. <br /> Arsenic was detected in two of six soil samples at concentrations ranging from 5.91 to <br /> 13.8 mg/kg. These values of arsenic were detected in soil samples colleted at depths <br /> of 25 to 29 feet bgs. <br /> The arsenic values detected exceed Residential Preliminary Remediation Goals of 0.39 <br /> ( mg/kg (cancer risk) and 0.062 mg/kg (A California Modified PRG). Please note, <br /> however that the mean value of arsenic in soil the western United States according to a <br /> U.S. Geological Survey Professional Paper 1270, titled "Element Concentrations in <br /> Soils and Other Surficial materials of the Conterminous United States," dated 1984 <br /> (EPA 1270 Professional Paper), is 5.5 mg/kg. Additionally it is Kleinfelder's experience <br /> that background arsenic values in the central valley can typically be much higher. It is <br /> Kleinfelder's opinion that the arsenic concentrations detected at the site are not atypical <br /> of background levels of arsenic in the Central Valley. Also arsenic detected at these <br /> depths would not be expected to be exposed to human receptors. Please note <br /> however the evaluation in the Dry Well Area was conducted to evaluate potential <br /> leaching of contaminants at depths adjacent to the dry wells. Therefore, naturally <br /> occurring arsenic may be near the surface at values exceeding PRGS and OEHHA <br /> health risk numbers. <br /> 6.1.2. Race Track Area <br /> Each of the LUFT five metals including cadmium, chromium, lead, nickel and zinc were <br /> detected from shallow soil samples collected in the interior Race Track Area (See Table <br /> 2). The values detected however were found to be below Residential PRGs and <br /> 1 OEHHA health risk values. <br /> 58671.E02/ST05R1127/DH:ly Page 17 of 22 <br /> ©2005 Kleinfelder, Inc. September 15,2005 <br />