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ARCADIS Ms. Kathy Amaru <br /> October 19, 2010 <br /> Shallow Soils(<3m bgs); Groundwater IS a Current or Potential Source of Drinking <br /> Water. Although shallow groundwater at the site is not known to be a drinking water <br /> source, these numbers were used for comparison to be as conservative. The <br /> screening levels used are provided in Tables 1 and 2. <br /> Excavation Confirmation Soil Analytical Results <br /> Concentrations of TPH as motor oil were detected above the RWQCB ESL of 83 <br /> mg/kg in 2 of the 9 excavation confirmation soil samples submitted for quantitative <br /> chemical analysis. The maximum concentration of TPH as motor oil was reported in <br /> sample EX-SB2-B, collected at the bottom of the SB-02/SB-13 excavation, at a <br /> concentration of 150 mg/kg. Sample EX-SB2-N, collected from the north sidewall of <br /> the SB-2/SB-13 excavation, contained a concentration of TPH as motor oil at 110 <br /> mg/kg. TPH as motor oil was detected below the RWQCB ESL in sample EX-SB2-E, <br /> collected from the east sidewall of the SB-02/SB-13 excavation, at a concentration of <br /> 37 mg/kg. TPH as motor oil was not detected above the laboratory reporting limit(27 <br /> mg/kg to 29 mg/kg) in any of the other six samples analyzed. <br /> TPH as gasoline and TPH as diesel were not detected at concentrations above the <br /> RWQCB ESL (83 mg/kg) in any of the soil samples submitted for analyses following <br /> excavation activities. <br /> Soil analytical results are presented in Table 1 and are also shown on Figure 3. The <br /> laboratory analytical report and chain-of-custody documentation are included as <br /> Appendix B. <br /> Groundwater Sampling <br /> As detailed above, groundwater sampling was proposed in the Site Sampling and <br /> Soil Removal Work Plan(ARCADIS, 2010a); however, no groundwater samples <br /> were collected during the April 2010 field activities because the groundwater level <br /> was deeper than the total advanced depth of the borings. Therefore, to characterize <br /> groundwater conditions near the excavation a temporary well point was installed for <br /> sample collection. <br /> Page: <br /> 7/12 <br /> 0111012775 d. <br />