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Soil and Groundwater Investigation Report Mountain House Development Site#6 July 2008 4.3 SOIL ANALYTICAL RESULTS Soil analytical results,PRGs, and ESLs for the COCs are summarized in Tables 2 and 3. A map of soil analytical results is provided on Figure 3. A data usability discussion is included in Appendix E as Appendix E.1, and copies of the soil sample laboratory analytical reports are included as Appendix E.2. Section 5.1 compares the soil analytical results to the PRGs and ESLs to assess the extent of affected soil and whether any further soil characterization is appropriate. 4.4 GROUNDWATER ANALYTICAL RESULTS The groundwater analytical results, ESLs, and WQOs are summarized in Tables 4 through 6. A map presenting the concentrations of the dissolved COCl in groundwater is provided on Figure 3. A data usability discussion is included in Appendix E as Appendix E.1, and copies of the groundwater sample laboratory analytical reports are included as Appendix E.2. Section 5.2 compares the groundwater analytical results to the ESLs and WQOs to assess the extent of affected groundwater and whether any further groundwater characterization is appropriate. 4.5 DATA USABILITY SUMMARY SAIC performed a data usability evaluation to determine whether the data could be used for the intended purposes (i.e., delineation,risk evaluation,remediation). The evaluation determined that all analytical data are usable. See the Data Usability Summary in Appendix E.1 for more information. Qualified data with reason codes are provided in Tables 2 through 6 and summarized in Appendix E.1. 4.6 FUEL-FINGERPRINT RESULTS The gas chromatography/mass spectrometry results of analyses of soil samples collected from soil borings SB-5 at 14 feet bgs, SB-10 at 17 feet bgs, and SB-14 at 23 feet bgs were compared with known standards of SJV crude and also to standards of Bunker C fuel oil,which may have been used as a cutter stock to reduce the crude-oil viscosity in the pipelines. The analyses concluded that all three samples contained moderately weathered SJV crude. Fuel-fingerprint results are summarized in Table 7, and the Chevron Energy Technology Company reports are provided in Appendix E as Appendix E.3. 5. DISCUSSION OF PETROLEUM DISTRIBUTION 5.1 EXTENT OF AFFECTED SOIL Soil analytical results were compared to the lowest,most conservative PRG and ESL concentrations for delineation purposes. Soil analytical results are summarized in Tables 2 and 3. The comparison indicated that soil sample analytical results obtained during this investigation were less than PRGs and ESLs,with the following exceptions: • TPHc were detected above the ESL screening levels in 11 soil borings. The highest TPHc concentration was detected in boring SB-21 at 6 feet bgs(29,000 mg/kg); and • Low concentrations of PAHs were detected above the ESL and/or PRG levels in four borings. The highest PAH concentration was detected in boring SB-10 at 18 feet bgs (phenanthrene at 12 mg/kg). COC concentrations in soil that exceeded PRGs and/or ESLs are shown on Figure 3. The soil analytical reports are included in Appendix E as Appendix E.2. 5.1.1 Distribution in Soil The site has three distinct areas of affected soil, as shown on Figure 3: • Area 1 is located at the northwestern portion of the site. This area consists of boring locations SB-9, SB-10, SB-11, and SB-15; 6 :: From Science to Solutions