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GENERAL ORDER FOR STOCKTON -2- DEEP WATER SHIP CHANNEL MAINTENANCE DREDGING PROJECTS additional constituents: TCDD Equivalents (Dioxins), Asbestos, Halogenated & Aroma..ic Volatile Organics, Acrolein & Nitriles, Nitrosamines and 1,2-diphenylhydrazine. Those sediment and elutriate water constituent concentrations that were much less than the most stringent of the three water quality evaluation parameters and/or were not detected above analytical methods were not identified as potential constituents of concern (COC). The constituents identified in Section A.3 are the resulting COC list. Two constituents did not follow the procedure described above for determining whether they should be a sediment COC; these were Tributyl Tin and Dioxins. Tributyl Tin was found in the sediments at levels far below those harmful to human health but was not detected in any of the decanted dredge return water samples. Dioxins were found in the sediments in the Stockton Deep Water Ship Channel. A report prepared by the State Water Resources Control Board indicates their likely source is a now shut-down wood treating operation in the Port of Stockton. This order only allows maintenance dredging and as such the material removed from the channel will be new material uncontaminated by dioxins. Therefore, both Tributyl Tin and Dioxins were not identified as a sediment COC. MAXIMUM DREDGE SEDIMENT CONSTITUENT CONCENTRATIONS Maximum Dredge Sediment Constituent Concentrations with No Return Water Back to the River The Maximum Sediment Constituent Concentration for each COC was obtained from the Sediment Screening Criteria for use of dredge materials as wetland creation cover identified in Table 2 of the Interim Sediment Screening Criteria and Testing Requirements for Wetland Creation and Upland Beneficial Reuse, prepared by the San Francisco Bay Regional Water Quality Control Board. Maximum Dredge Sediment Constituent Concentrations with Return Water to the River The dredge sediment criteria for discharge of dredge return water were developed to protect the receiving water beneficial uses and prevent violations of water quality objectives. They were developed based on testing done by the COE relating sediment quality to return water quality, and calculations of allowable discharge concentrations based on receiving water quality, available dilution and water quality criteria. The following constituents used this method for establishing the sediment limit: Arsenic, Lead, and Thallium. When the Maximum Dredge Sediment Constituent Concentration with no Return Water Back to the River was more restrictive then this value was utilized in both discharge conditions. Such was the case for Copper, Mercury and Zinc.