ARCHIVED REPORTS_DRAFT - PHASE I REMEDIAL INVESTIGATION REPORT

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Kennedy/Jenks Consultants • rSection 7: Recommendations Recommendations regarding potential future activities are also provided for each operable unit, as well as on a site-wide basis. In order to allow for productive use and redevelopment of the individual operable units, each unit should be addressed separately as needed to meet redevelopment schedules. 7.1 Operable Unit 1 OU-1 will remain industrial use. Portions of OU-1, especially in AOI 2, were previously excavated to remove soil containing lead at concentrations exceeding 220 mg/kg. As previously discussed in this Report, soil sampling was performed in OU 1 to evaluate the effectiveness of the previous soil remediation activities. Analytical results from the soil samples collected in AOI 1 indicate that concentrations of total lead in soil between 0 and 10 feet bgs are less than residential CHHSL and PRG values. Therefore, no further subsurface investigation activities are recommended to characterize lead in soil in AOI 1. Analytical results from the soil samples collected in AOI 2 and AOI 3 indicate that surface and near-surface soils in several locations contain total lead concentrations exceeding CHHSL and • PRG values. Prior to future redevelopment of OU-1, a risk assessment should be performed to evaluate acceptable residual lead concentrations based on the planned future use. 7.2 Operable Unit 2 The anticipated future use of OU-2 has not yet been identified. As described in the RI Work Plan, numerous maintenance operations were historically performed in OU-2, and therefore, the presence of TPH in soil is not unanticipated. Additional characterization of the lateral and vertical extent of elevated TPH and arsenic concentrations in soil is recommended. Depending upon the anticipated future land use in OU-2, redevelopment plans and the results of a risk assessment, remediation of soil containing elevated concentrations of TPH and/or arsenic could be performed in conjunction with redevelopment activities. Further assessment of the lateral extent of TPH in groundwater in AOI 7 is recommended. Future groundwater characterization in OU-2 does not need to include analysis of VOCs. 7.3 Operable Unit 3 It is currently anticipated that OU-3 will be redeveloped as part of a multimodal facility. Under this scenario, the future land use would be commercial, and the majority of the area would be paved or occupied by structures or landscaping. Based upon the analytical results described herein, and the redevelopment plans, no further action is recommended to characterize soil within OU-3. DRAFT Phase I Remedial Investigation Report Page 47 Former Tracy Railyard, Tracy, California g:Gs-groupladmin\job\05\0565777.18_uprr\09-reports\ri rpt\teAdoc