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Kennedy/Jenks Consultants <br /> • <br /> If monitoring wells are installed in OU-5, groundwater samples from the wells should be <br /> collected and submitted for analysis of dissolved metals to provide a more direct comparison <br /> with MCL values. <br /> 7.6 Site-Wide <br /> 7.6.1 Soil <br /> Other than lead and arsenic, analysis of future soil samples for metals is not necessary. <br /> Moreover, future analysis of soil samples for lead need not to include soluble lead, unless <br /> excavated soils are being characterized for the purposes of offsite disposal. Extensive analysis <br /> of soil samples collected from OU-1 indicates that soluble lead concentrations correlate very <br /> well with total lead concentrations in soil. <br /> Similarly, as described herein, analytical results indicate that VOCs, SVOCs, PAHs and <br /> pesticides are not chemicals of further interest in soil at the Railyard. The analytical suite for <br /> future soil samples does not need to include VOCs, SVOCs, PAHs or pesticides. <br /> 7.6.2 Groundwater <br /> As discussed above, groundwater in several portions of the former Railyard contains elevated <br /> concentrations of TPH, and additional investigation activities are recommended to further <br /> delineate the lateral and vertical extent of TPH in groundwater. However, analysis of future <br /> reconnaissance groundwater samples for metals is not recommended, and the analytical suite <br /> for future groundwater samples does not need to include VOCs or SVOCs. <br /> Installation of9 roundwater monitoring wells is recommended to allow monitoring of TPH <br /> concentrations in groundwater in AOI 10 and potentially in OU-2. Water level data from <br /> groundwater monitoring wells can be used to estimate the groundwater flow direction and <br /> gradient. Monitoring wells may also be useful in estimating the hydraulic conductivity and <br /> permeability of the aquifer zone. <br /> 7.6.3 General <br /> Future redevelopment of the former Railyard should anticipate encountering residuals from <br /> former Railyard operations (ballast, slag ballast, purple-colored soils, etc.) and include <br /> provisions for the segregation, evaluation and appropriate offsite disposal of encountered <br /> residuals. Union Pacific should expect to include requirements for segregation of these <br /> materials in its Purchase and Sales Agreements. <br /> Following implementation of additional subsurface characterization activities, the human health <br /> risk assessment identified in the Voluntary Cleanup Agreement should be performed to identify <br /> appropriate residual chemical concentrations in soil and groundwater at the former Railyard. <br /> • <br /> DRAFT Phase I Remedial Investigation Report Page 49 <br /> Former Tracy Railyard, Tracy, California <br /> g:\is-group\admin\job\05\0565777.1 8_uprA09-reports\ri rpt\teddoc <br />