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k4 KLEINEELDER The range of concentrations for these metals did not exceed the Total Threshold Limit Concentration (TTLC) Regulated Level for classification of the metals as a hazardous waste per California Code of Regulations 22CCR §66261.24. Additionally these concentrations were not greater than 10-times the Soluble Threshold Limit Concentration (STLC) Regulated Level for these metals as expressed in 22CCR §66261.24. The factor of 10-times the STLC Regulated Level is commonly used as an indicator as to whether or not a STLC analysis is appropriate to be ran on the sample. The concentrations of nine of the eleven soil samples were found to be below the residential and industrial PRGs for these metals in soil. Arsenic was detected in three soil samples in this area at concentrations exceeding the residential and industrial PRG of 0.39 and 1.6 mg/kg, respectively. However the mean value of arsenic in soil in the western United States according to a U.S. Geological Stu-Vey Professional Paper 1270, titled "Element Concentrations in Soils and Other Surficial materials of the Conterminous United States," dated 1984 (EPA 1270 Professional Paper), is 5.5I mg/kg. Based on this source and from Kleinfelders experience in the San Joaquin Valley, it is Kleinfelder's opinion that the arsenic concentrations detected in this area are likely reflective of background concentrations. i Mercury was detected in one soil sample at a concentration of 0.16 mg/kg. This value is below the former (11/l/00) Residential PRG for "mercury and compounds" with a non carcinogenic hazard of 23 mg/kg. The most current PRGs as of 10/1/02 however have a goal of 0.0 mg/kg for "elemental" mercury and no longer have a goal for "mercury and compounds". Because the analytical results reported are for total mercury, which would include mercury and compounds, a direct comparison is not possible at this time to the new elemental mercury goal. POND AREA Three 4-point composite samples were collected in the pond areas and analyzed for TPH-D and TPH-MO, and organochlorine pesticides. Table 4 summarizes the petroleum and pesticide results. No TPH-D or organochlorine pesticides were detected. TPH-MO was detected in two of the 4-point composite soil samples at concentrations ranging from 5.9 to 6.5 mg/kg. These values appear to be deminimus quantities of TPH-D and based on Kleinfelder's experience would not generally trigger additional sampling or enforcement actions by regulatory enforcement agencies. FORMER CHEMICAL STORAGE AREA Six discrete soil samples were collected in a former organophosphate pesticide chemical storage area. The samples were collected at depths ranging from 0 to 3 feet bgs. No organophosphate pesticides were detected in any of the six shallow soil samples collected in this area (see Table 7). Based on this information, Kleinfelder does not recommend further assessment in this area for organophosphate pesticides. 4 i 36274/ST03RI919 Page 13 of 19 I v 2004 Kleinfelder, Inc. January 5,2004 f s