ARCHIVED REPORTS_DRAFT - PHASE I REMEDIAL INVESTIGATION REPORT

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Kennedy/Jenks Consultants Table 12. PAHs were not detected at concentrations exceeding analytical reporting limits. Only one pesticide was detected at concentrations exceeding analytical reporting limits; 4,4'-DDT was detected at a concentration of 20 pg/kg in sample OU5-AO1 11-TS-4-0.5, the sample of the purple-colored material. This concentration is less than the residential PRG and CHHSL comparison values. TPHg, BTEX, and TPHmo were not detected at concentrations exceeding analytical reporting limits in any of the soil samples collected from below the wood pipeline. TPHd was detected in sample OU5-AO1 1 2-TS-4-2.5 at a concentration of 1.3 mg/kg. TPHd and TPHmo were detected in sample OU5-AOl12-TS-4-1.3 (adjacent to the wood pipe), at concentrations of 120 mg/kg and 510 mg/kg respectively. The black material collected in sample OU5-AO112-TS-8-2 contained TPHd at 1,500 mg/kg and TPHmo at 5,500 mg/kg, but TPHg, BTEX, and PAHs were not detected in this sample at concentrations exceeding analytical reporting limits. Other analytes were not detected at concentrations exceeding analytical reporting limits in any of the other samples collected from the trenches. Groundwater Sam 5.7.5 OU-5 les p Three reconnaissance groundwater samples were collected from borings in AOI 9 and sixteen reconnaissance groundwater samples (including two duplicates) were collected from 14 borings in the AOI 10 area. The borings were located to evaluate the western, northwestern, and southern extent of the TPH previously discovered in groundwater by Geocon. Borings were advanced to the north and south along the railroad tracks until visible signs of hydrocarbon impact were not observed in the aquifer material or in groundwater. Borings were advanced on the west side of the railroad tracks to assess if the western limit of the hydrocarbons could be observed. 5.7.5.1 Metals Analytical results for metals concentrations in the reconnaissance groundwater samples collected from AOI 10 are presented in Table 13. Although shallow groundwater beneath OU-5 may not be considered a potential source of drinking water, and the groundwater samples were not filtered prior to analysis, and thus the reported data reflect total metals concentrations, MCLs are provided in Table 13 as preliminary comparison values. Although the analytical results for several metals exceed MCL values, it is anticipated that much of the reported metals concentrations are associated with suspended solids in the samples. 5.7.5.2 Organic Compounds Analytical results for organic compounds from reconnaissance groundwater samples collected in and west of OU-5 are summarized in Table 14. TPH concentrations in reconnaissance groundwater samples collected near and in AOI 10 are posted on Figure 12, which also includes data from Geocon (2004) to illustrate historical findings. As shown in Table 14, three reconnaissance groundwater samples collected in AOI 9 in eastern OU-5 were analyzed for TPHg, TPHd, TPHmo, and BTEX. TPHg, BTEX, and TPHmo were not DRAFT Phase 1 Remedial Investigation Report Page 35 Former Tracy Railyard, Tracy, California g:\is-group\adminl ob105\0565777.18_uprr\09-reports\ri rpMezLdoc