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Kennedy/Jenks Consultants <br /> associated with the slag ballast observed in this area. In several sampling locations, arsenic <br /> concentrations exceeding background concentrations are also present in the surface soil <br /> samples, corresponding with the elevated lead concentrations. Lead and arsenic, especially in <br /> shallow soil are considered chemicals of continued interest in OU-5. <br /> Four soil samples from OU-5 were analyzed for VOCs, and another 50 soil samples from OU-5 <br /> were analyzed for BTEX and MTBE. Of these, only two samples contained BTEX and/or VOCs <br /> at concentrations exceeding analytical reporting limits. These two samples were collected from <br /> depths greater than 15 feet bgs in borings along the west side of the railroad tracks west of <br /> AOI 10. Samples of the underlying groundwater at these two locations did not contain <br /> concentrations of BTEX exceeding analytical reporting limits, although elevated concentrations <br /> of TPHmo and TPHd were present in both groundwater samples. <br /> Previous subsurface investigations had identified the presence of TPH in soil within AOI 10 <br /> (Geocon; 2004, 2005), including a potential source area in the vicinity of Boring G-134 (location <br /> shown on Figure 10). Soil samples collected during this recent investigation confirmed the <br /> presence of TPH in soil in scattered locations within OU-5, but did not indicate any additional <br /> TPH source areas. <br /> Thirteen soil samples collected from OU-5 were submitted for analysis of PAHs. None of the <br /> ' samples contained PAHs at concentrations exceeding analytical reporting limits. Four soil <br /> samples collected from AOI 11 in OU-5 were submitted for analysis of pesticides. None of the <br /> samples contained pesticides at concentrations exceeding analytical reporting limits. On the <br /> basis of these analytical results, pesticides and PAHs are not considered chemicals of further <br /> interest in OU-5. <br /> 6.5.2 Groundwater <br /> Fourteen reconnaissance groundwater samples collected within and west of AOI 10 were <br /> analyzed for total metals. Reconnaissance groundwater samples typically have a higher <br /> suspended solids concentration than samples from monitoring wells, and these reconnaissance <br /> samples were not filtered prior to analysis. Therefore, the reported values reflect both the <br /> dissolved and suspended metals contributions. Although the analytical results for several metals <br /> exceed the MCL comparison values, it is expected that the dissolved metals concentrations <br /> would be significantly less the total metals values reported in Table 13. <br /> Although benzene was detected in one of the 14 groundwater samples collected within and <br /> west of OU-5, and xylenes were detected in another groundwater sample, both concentrations <br /> were reported just atahn BTEXtoraMTBE at reporting <br /> limits. <br /> concentrat onsother <br /> groundwater <br /> samples did not con exceeding analytical reconnaissance reporting limits. <br /> The analytical results from 14 reconnaissance groundwater samples collected from within and <br /> west of AOI 10 indicate that BTEX and MTBE are not chemicals of interest in groundwater west <br /> of AOI 10. Moreover, on the basis of the analytical results described herein, other VOCs are not <br /> considered chemicals of interest in OU-5 groundwater. <br /> DRAFT Phase 1 Remedial Investigation Report <br /> Page 44 <br /> Former Tracy Railyard, Tracy, California <br /> g:\is-group\admin\job\05\0565777.18—uprr\09-reportsVi rpl\lext.doc <br />