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1 KLE//VFELOER <br /> Bright People,Fight 5ol­ons. <br /> The shallow soils from 0 to 5 feet bgs appear to be impacted with TPH-MO with <br /> concentrations ranging from 72 mg/kg to 4,300 mg/kg. The highest concentrations <br /> appear to be around B-2 and B-3 with concentrations decreasing to non-detectable <br /> results thereafter. B-4 has no detectable concentrations below 5 feet bgs, while <br /> concentrations in B-1 decrease but are still detectable at relatively low concentrations <br /> (48 mg/kg) as deep as 15 feet bgs. According to published Environmental Screening <br /> Levels (ESLs), developed by the San Francisco Regional Water Quality Board (Interim <br /> Final dated May 2008) the ESL for TPH "residual fuels" is 2,500 mg/kg (Table A, <br /> Shallow Soils, with groundwater considered a potential source of drinking water). Two <br /> soil samples collected at depths of 3 '/2 (B-3) and 5 feet bgs (B-2) had values exceeding <br /> this value. <br /> TPH-D was detected in the grab groundwater sample collected from location B-1 with a <br /> concentration of 14 mg/L. The detection of TPH-D with this concentration is relatively <br /> high compared to the ESL and EPA taste and odor threshold which are both 0.1 mg/I or <br /> 0.056 to 0.15 mg/L for the Integrated Risk Information System (IRIS) for diesel oil. <br /> The groundwater sample also contained some VOCs. Isop ropy]benzene, sec- <br /> butylbenzene, and tert-butylbenzene were detected with concentrations of 1.1, 8.4, and <br /> 2.7 ug/L, respectively. The State action level for Isopropylbenzene is 700 ug/L <br /> (RWQCB 2004), and the California State Notification Level (CDPH) for sec- and tert- <br /> butlybenzene is 260 ug/L. Neither regulatory limit of the detected VOCs exceeded the <br /> regulatory limits. <br /> Based on analytical data it appears that TPH extractable range contamination is <br /> present in the near surface and at least to a depth ranging from 5 to 10 feet bgs, near <br /> locations B-2 and B-3. The laboratory data suggests an attenuation of TPH-MO with <br /> depth thereafter in most soil samples. However, field observations were noted of a <br /> strong petroleum odor, and a PID reading of 162 ppmv near groundwater and TPH-D <br /> concentrations were detected in groundwater. The TPH-D concentration while not <br /> significantly elevated, did exceed a number of published screening levels/goals. A <br /> relatively large VOC suite was run on the water sample and was largely negative except <br /> for three VOCs which were detected at relatively low values and below noted regulatory <br /> goals. Based on the field observations and PID readings, the analytical results <br /> 112884.1/ST010R366R Page 7 of 10 October 1, 2010 <br /> Copyright 2010 Kleinfelder Revision 1,dated November 22,2010 <br />