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Soil Boring Report—Former Unocal Station No 0123,Tracy, California <br /> . March 10 2000 <br /> The soil boring was advanced by Geoprobe technology on January 12, 2000 The Geoprobe advances <br /> hydraulically and does not generate soil cuttings The boring was first cleared to 5 feet bgs by hand <br /> auger, then advanced to 16 feet bgs by Geoprobe A GR geologist observed the Geoprobe activities, <br /> collected one soil sample at 7 feet bgs and a grab groundwater sample for chemical analysis, described the <br /> encountered soil, and prepared a log of the boring Upon completion the boring was backfilled with neat <br /> cement from 5 to 16 feet bgs, then cuttings generated during hand augering were placed back in the <br /> boring and compacted to within 0 5 feet of ground surface, and the boring was finished to ground surface <br /> with asphalt patch as required by the City of Tracy The boring log is included in Appendix C Mr Mike <br /> Infurna of the SJCEHD was present to observe the Geoprobe and sample collection activities <br /> RESULTS OF THE SUBSURFACE INVESTIGATION <br /> Soil encountered during this investigation consisted of silt and silty clay to 6 5 feet bgs A sandy silt <br /> extends from 6 5 to 15 9 feet bgs The bottom 0 1 feet of the boring was silty sand At 8 5 feet bgs the <br /> soil became saturated, and from approximately 9 5 to 15 5 feet bgs the soil had a strong hydrocarbon <br /> odor <br /> CHEMICAL ANALYTICAL RESULTS <br /> Soil and grab groundwater samples from the boring were submitted under cham-of-custody for chemical <br /> analysis Analyses were performed by Sequoia Analytical of Sacramento, California (FLAP #1624) <br /> Copies of the laboratory report and chain-of-custody form are included in Appendix D Soil and <br /> groundwater chemical analytical data are summarized in Tables 1 and 2, respectively <br /> Chemical Anal3jical Procedures <br /> The soil and grab groundwater samples were analyzed for TPHg, benzene,toluene, ethylbenzene and total <br /> xylenes (BTEX), and TPHd by DHS LUFT, tert-butyl alcohol (TBA), MtBE, di-isopropyl ether (DIPE), <br /> ethyl tert-butyl ether (ETBE), and ethanol by EPA Method 8260A, methanol by EPA Method 8015 <br /> (modified), and VOCs by EPA Method 8010B <br /> Soil Analytical Results <br /> TPHg, BTEX, TBA, MtBE, DIPS, ETBE, TAME, methanol, or VOCs were not detected in the soil <br /> sample Unidentified hydrocarbons in the TPHd range (C10-C24) and ethanol were detected at <br /> concentrations of 2 21 and 150 ppm, respectively <br /> Groundwater Analytical Results <br /> Oxygenates were not detected in the grab groundwater sample Weathered gasoline and unidentified <br /> hydrocarbons in the TPHg range (C6-C12), benzene, and unidentified hydrocarbons in the TPHd range <br /> (C10-C20)were detected at concentrations of 66,700 ppb, 36 2 ppb,and 29 6 ppm, respectively <br /> • 24007303-1 3 <br />