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1 r <br /> 07 February 1997 <br /> AGE-NC Project No 96-0266 <br /> Page 4 of 8 <br /> nickel, silver and zinc Samples were analyzed in accordance with the appropriate EPA methods <br /> 5030/8015m, 80201602, 335 2, and 6010/9010 One soil sample, I-1, was analyzed using a STLC <br /> (soluble threshold limit concentration)extraction for lead in accordance with California Title 22 and <br /> ' EPA methods 6010 Grab ground water samples from probe borings P6 and P8 were not analyzed <br /> Specific laboratory analytical methods for each sample are included with the laboratory reports in „ <br /> Appendices B and C <br /> ' 4.0 FINDINGS <br /> 41 STRATIGRAPHY <br /> ' Tan and brown, silty clay was encountered in each probe boring from surface grade to depths of <br /> approximately ten feet bsg, gray, silty sand was encountered at depths between 10 and 15 feet bsg <br /> ' Coarse-grained sand to gravel was distributed below the silty sands, from depths of 15 to <br /> approximately 19 feet Finally, a gray silty clay was encountered at a depth of twenty feet in most <br /> probe borings A typical boring log is included in Appendix A <br /> ' 42 HYDROCARBON-IMPACTED SOIL <br /> TPH-g, BTE&X and MTBE were detected in soil samples collected from probing PI at <br /> concentrations as high as 3,700 mg/kg(milligrams per kilograms or parts per million ppm) TPH-g, <br /> toluene,ethyl benzene and xylenes were also detected in one soil sample collected from probing P 12, <br /> at concentrations up to 61 ppm Petroleum hydrocarbons were not detected in soil samples collected <br /> ' from any other probings advanced during this investigation <br /> Laboratory results of soil samples analyzed for petroleum hydrocarbons area summarized in Table <br /> ' 1 The laboratory reports(MAI Laboratory ID 71282 to 71296,72947 to 72963), QA/QC reports and <br /> chains-of custody are included in Appendix B <br /> 43 HYDROCARBON-IMPACTED GROUND WATER <br /> ' TPH-g was detected in four of ten grab ground water samples collected from the UST area at <br /> concentrations ranging from 84 to 44,000 µg/l (micrograms per liter or parts per billion ppb) <br /> BTE&X were detected in six of ten samples analyzed at concentrations ranging from 0 60 to 7,800 <br /> ppb TPH-d was detected in four of five grab ground water samples analyzed at concentrations up <br /> to 6,600 ppb (P14) The approximate lateral extents of dissolved hydrocarbons are depicted on <br /> 1 <br />