Mid-Columbia River Feasibility Study: Physical and Chemical Analyses of Hanford Reach Sediments

摘要

The National Marine Fisheries Service has long been involved in research on the fisheries and habitat priority issues of: (1) dams and hydroelectric power generation; (2) point and non-point source industrial waste discharge; and (3) waterway development (including dredging, filling, and dredge disposal). Because sedimentation and siltation are occurring to some extent in the forebays and reservoirs of Columbia River dams, it may eventually be necessary to dredge in some of these areas. Information on the nature, origin, and extent of industrially-discharged materials which may have accumulated at sites subject to future excavation will contribute to salmonid and habitat management in the Columbia River Basin by state and federal fishery and environmental agencies, Indian tribes, and power entities. The entire United States mainstem Columbia River is impounded behind a succession of dams except for a 52-mile section which extends from Richland, Washington, at River Mile (RM) 345 upriver to Priest Rapids Dam (RM 397). Commonly termed the Hanford Reach, this section remains the only free-flowing segment of the Columbia River above Bonneville Dam (RM 145); it provides a large mainstem spawning area for a valuable population of fall chinook salmon. It has been proposed by the COE that a shallow-draft navigation channel be established through the Hanford Reach to accommodate river barge transportation upstream to the Wenatchee, Washington, area (RM 470). As the excavation of the channel may result in the resuspension and release of any contaminants associated with the sediments, a determination of potentially hazardous materials in the sediments is of primary concern. The specific objectives of the present study were to: (1) provide appropriate physical and chemical analyses of representative samples of sediment likely to be dredged from the Hanford Reach and (2) provide an evaluation of the potential for the introduction of contaminants into the water column.