Maintenance dredging potentially produces an estimated 15 000 m3 of sedimentary material from the Calumet‐Sag Channel (Cal‐Sag) annually. To determine the suitability of this dredged material for use in the reclamation of abandoned mined lands, 10 sediment samples were taken at 2.4‐km intervals along the length of the Cal‐Sag using a gravity corer. Sediment cores (107 to 173 cm in length) were subdivided to represent 40‐ to 50‐cm depth increments, and composite samples were taken along the length of each subsample. Organic pollutant concentrations as well as silt and clay contents were determined. No significant correlations existed between each organic pollutant concentration and sediment sample depths, locations, or sediment silt or clay content. This result suggested that the mean and the mean plus twice the standard deviation offered good approximations of the expected mean value and the expected (95%) maximum value for these pollutants in Cal‐Sag dredged material (volatile solids: 9.85 and 13.1 mg/kg; oil and grease: 11.9 and 22.7 g/kg; total phenols: < 2.4 and < 4.8 mg/kg; and total polychlorinated biphenyls (PCB's): 7.0 and 17 mg/kg). Polycyclic aromatic hydrocarbon (PAH) levels were determined for nine selected Cal‐Sag sediment samples. Measured parent PAH compound levels (46 compounds) exceeded 80 mg/kg in only one sample. Alkyl‐substituted PAH compound concentrations were measured for three parent compounds in three sediment samples and found to be highly variable in concentration (∼ 1 – ∼ 500 mg/kg).
As part of the U.S. Department of Energy's evaluation of site suitability for a potential high-level radioactive waste repository, long-term interactions between the engineered barrier system and the site must be determined. This requires a waste-package/engineered-system design, a description of the environment around the emplacement zone, and models that simulate operative processes describing these engineered/natural system interactions. Candidate designs are being evaluated, including a more robust, multi-barrier waste package, and a drift emplacement mode. Tools for evaluating designs and emplacement mode are the currently available waste-package/engineered-system performance assessment codes developed for the project. For assessments that support site suitability, environmental impact, or licensing decisions, more capable codes are needed. Code capability requirements are being written, and existing codes are to be evaluated against those requirements. Recommendations are being made to focus waste-package/engineered-system code-development.
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