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Stantec <br /> PEA WORKPLAN <br /> Proposed Lodi Energy Center Site <br /> Lodi, California <br /> 7.0 SELECTION OF SCREENING CRITERIA <br /> Based on the results of the scoping meeting, a few modifications to the standard PEA <br /> requirements are proposed. These include utilizing exposure point concentrations (EPCs) <br /> based on the 95 percent upper confidence limit (UCL) of the mean (rather than maximum <br /> concentrations) for comparisons with risk-based screening levels based on industrial worker <br /> (rather than residential) exposure assumptions. In addition, the soil sample metals results will <br /> be compared with existing background data using a Wilcoxon-Rank Sum or similar test. EPCs <br /> will be generated for each exposure area using US EPA Pro-UCL Version 4.0 software. For <br /> organic compounds detected at least once in an exposure area and for metals and PAHs <br /> exceeding background levels, the ratio of the EPCs to the screening-level criteria will be <br /> calculated for each analyte as a measure of risk. Cumulative risk will be calculated for both <br /> carcinogenic and non-carcinogenic effects, using the screening criteria accepted by DTSC. <br /> Stantec proposes to compare soil analytical data to the following risk-based screening criteria <br /> using a hierarchical approach in the order listed below: <br /> • California Human Health Screening Levels (CHHSLs)for commercial/industrial land use; <br /> • USEPA Regional Screening Levels (RSLs) for industrial soil; and <br /> • Where a CHHSL or RSL screening value does not exist, detected concentrations will be <br /> compared to San Francisco Regional Water Quality Control Board Environmental <br /> Screening Levels (ESLs) Shallow Soil Screening Levels (< 3 meters bgs), <br /> Commercial/Industrial land use where groundwater is not a current or potential drinking <br /> water source. <br /> Stantec proposes to compare groundwater analytical data to California Maximum Contaminant <br /> Levels (MCLs). <br /> PEA WP-Lodi 16 August 13,2009 <br />