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W r 4 3Cw-w rpt LEEG5HiLL•HERKENHOFF.SNC. The laboratory analyzing the soil samples for these constituents was Superior Analytical, Inc., a California Department of Health Services (DOHS) certified laboratory. Included in Appendix D is Superior Analytical's DOHS certificate, as well as the chain-of-custody forms and analytical results. Soil samples were also collected from the continuous core at soil boring S31 for sieve analysis to confirm the USCS classification. The testing method used for the sieve analysis conforms to ASTM Method D422-63(A72). The laboratory performing the geotechnical analysis was Harding Lawson Associates (HLA). These geotechnical results and the sampl W chain-of-cus%uuy are included in Appendix C. E ' 3.5 SOIL SAMPLING RESULTS As previously discussed, soil samples were collected from the eight soil borings and the three monitoring well borings. These samples were analyzed for BTX&E and TPH as gasoline. Selected samples from soil boring SB6 were also analyzed for TPH as diesel. Individual certificates of analysis are included in Appendix D. Table 2 summarizes the analytical soil sampling results, Soil Borings Surrounding the Farmer UST Excavation. Analysis of soil samples collected from borings SBI, SBS, S87, SBS, and MWS which surround the former UST excavation contained no detectable level of TPH as gasoline at all depths analyzed. Soil samples from soil boring MW1 contained no detectable levels of TPH at all depths sar,.pled except for a depth of 20 feet at which the TPH concentration equalled the laboratory detecti3n limit. No detectable levels of BTX&E Were found in boring S81 and SB5 at all depths i analyzed. Low'concentration levels of one or more of the BTX&E constituents were found in boring SB7 to a depth of 16.5 feet, S68 to a depth of 31.5 feet, MW1 to a depth of 21.5 feet, and MW3 to a depth of 31.5 feet indicating that some petroleum hydrocarbon soil contamination has migrated to at least those depths at their respective locations. Analysis of soil samples from boring MW2 indicates low levels of petroleum hydrocarbon constituents above and below a depth of 16.5 feet. However, at a depth of 16.5 feet, high concentrations of toluene, ethylbenzene, xylene, and TPH as gasoline were detected. This contamination is present in a silty sand layer i and indicates that the soil contamination may have migrated off-site to the north of the former excavation. Soil Borings Within the former UST Excavation Analysis of soil samples collected from borings SB2, SB3, and S84 drilled within [ ' theexcavation found TPH as gasoline concentration levels ranging from non detect ---- ----- ---___ -.....__ to---100-mg/kg SB2--contained-relatively low-concentrations (7 mg/kg) at a depth of 11.5 feet and non-detect at a depth of 21.5 feet.. S84 contained a high concentration of TPH as gasoline at a depth of 11.5 feet (2000 mg/kg) and relatively low concentrations of TPN zo gasoline (10 m kg or less) 1 u� 14 say ,