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Kennedy/Jenks Consultants <br /> In Boring OU2-AOI4-S2, the TPH concentrations decrease with increasing depth, with the <br /> highest TPHd and TPHmo concentrations found in the surface soil sample and the lowest <br /> concentrations in the sample collected from 10 feet bgs. The TPHd and TPHmo concentrations <br /> in Boring OU2-AOI4-S3 also decrease with increasing depth overall. <br /> Acetone and tetrachloroethene (PCE) were detected at concentrations of 140 micrograms per <br /> ' kilogram (Ng/kg) and 5.0 pg/kg, respectively, in sample OU2-AOI4-S-1-10/11. Both of these <br /> concentrations are less than the respective residential PRGs. SVOCs were not detected at <br /> concentrations exceeding analytical reporting limits in any of the 12 soil samples collected from <br /> AOI 4. <br /> The results indicate that hydrocarbons have been released to soil in AOI 4. TPH has been <br /> observed to a depth of at least 20 feet bgs at Boring OU2-AOI4-S1, and TPH has been detected <br /> in the other two borings to a depth of 11 feet bgs. <br /> 5.4.2 OU-2 AOI 4 Groundwater Sample <br /> A groundwater sample was collected from Boring OU2-AOI4-S1 and analyzed for TPHd, <br /> TPHmo, and VOCs. As shown in Table 8, TPHd was detected at 610 pg/I, and TPHmo and <br /> VOCs were not detected at concentrations exceeding analytical reporting limits. <br /> 5.4.3 OU-2 AOI 5 Soil Samples <br /> AOI 5 includes the area where the oil tank and associated structures, including a pump house <br /> railroad tracks, and various drains and pipes, were formerly located. Soil samples collected from <br /> ' AOI 5 were analyzed for TPHd, TPHmo, VOCs, SVOCs, and samples from one boring were <br /> analyzed for Title 22 metals. <br /> 5.4.3.1 OU-2 AOI 5 Soil Samples — Metals <br /> Four soil samples from Boring 0U2-AOI5-S1 were analyzed for Title 22 metals. As shown in <br /> Table 6, antimony, beryllium, mercury, molybdenum, selenium, silver, and thallium were not <br /> detected at concentrations exceeding analytical reporting limits in the four samples. <br /> The other detected metal concentrations were less than the respective comparison values <br /> except for arsenic, which was found at concentrations ranging from 2.5 to 5.4 mg/kg. <br /> 5.4.3.2 OU-2 AOI 5 Soil Samples — Organic Compounds <br /> ' Organic compounds are tabulated in Table 7, which includes samples from the original borings <br /> and "replacement" Borings OU2-AO15-S2-R, OU2-AO15-S3-R, and OU2-AO15-S4-R. As <br /> described in Section 3.2.4, these borings were drilled to collect samples for VOC analysis only. <br /> TPHd and TPHmo were detected at elevated concentrations in the surface soil samples <br /> analyzed for TPH. The maximum concentrations were 7,000 mg/kg of TPHd and 15,000 mg/kg <br /> ' of TPHmo in sample OU2-AO15-S-4-0/0.5. As shown in Table 7, in each AOI 5 boring the TPH <br /> • concentrations decreased with depth from the surface to 5 feet bgs, but the TPH concentrations <br /> DRAFT Phase I Remedial Investigation Report Page 25 <br /> Former Tracy Railyard, Tracy, California <br /> g:6s-groupladminljob\0510585777.18_upr609-reportsVi rptVextdoc <br />