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Table 5:Remediation Goals for COCs/COECs Geosyntec Consultants in Soil and Sediment Rough and Ready Island, Site 47 Port of Stockton Minimum Detected Maximum Detected 95% Upper Confidence Risk-Based 3 4 Exposure Scenario COC/COEC Concentration Concentration 1 Limit of Mean Screening Level BTV Remediation Goal (mg/kg) m /k Concentration Z m /k (mg/kg)(mg/kg) g g (mg/kg) Arsenic 3.3 1,490 172.8 0.36 30.7 30.7 Benzo(a)anthracene 0.048 19 0.733 12 -- 12 Human Health Commercial/ Benzo(a)pyrene 0.037 26 0.198 1.3 -- 1.3 Industrial Benzo(b)fluoranthene 0.04 30 1.592 13 - 13 (Soil) Dibenzo(a,h)anthracene 0.049 4.4 -- 0.31 0.31 Indeno(1,2,3-c,d)pyrene 0.046 19 0.887 13 - 13 Ecological Arsenic 3.3 1,490 172.8 68 30.7 68 (Soil and Sediment) Total DDT5'6 0.0018 1.8 0.237 0.329 -- 0.329 Abbreviations: BTV=background threshold value HQ=hazard quotient COC=contaminant of concern LOAEL=lowest-observed-adverse-effect level COEC=contaminant of ecological concern mg/kg=milligrams per kilogram DDT=4,4'-dichlorodiphenyltrichloroethane RIFFS=remedial investigation/focused feasibility study DTSC=Department of Toxic Substances Control RRI=Rough and Ready Island ERAS=Ecological Risk Assessment Section Notes: 1 The human health risk assessment used maximum detected concentrations for COCs to estimate theoretical excess lifetime cancer risk and non-cancer health effects. 2 The ecological risk assessment evaluated soil and sediment data with the upper 6 feet,and estimated 95%upper confidence limits of the mean concentrations for each COEC. 3 BTV for RRI developed by the DTSC ERAS(2015). 4 The BTV was selected as the remediation goal where it was a higher value than the risk-based screening level. 5 While total DDT was not identified as a COEC on a site-wide basis,it is recognized that there is a hot spot within the bank soil and sediments within the drainage channel. 6 The total DDT risk-based screening level was established using the site-specific food web model(Appendix F of Site 47 RI/FFS);the risk threshold(LOAEL-based HQ)was set to 1 and the associated corresponding soil exposure point concentration that would lead to no potential risks(HQ<1)was iteratively determined. 7 The remediation goals for sediment are based on risk-based screening levels for soil as the alternatives being considered involve placement of a clean soil cover. Page 1 of 1