Eddy Pump Dredging Demonstration at Cresta Reservoir

by Larry L. Harrison, (M.ASCE),
Harry P. Weinrib,



Document Type: Proceeding Paper

Part of: North American Water and Environment Congress & Destructive Water

Abstract:

A demonstration test of a new environmentally ifiendly slurry dredging technology using the EDDY Pump, a patented vortex slurry pump, was perfbrmed in 1994 at Cresta Reservoir in northern California to veril its performance capabilities and to determine the potential environmental impacts of proposed dredging. The reservoir, located on the North Fork Feather River in Plumas County, has accumulated approximately 2.3 million cubic meters of sediment, filling almost half its total capacity since it was placed in service in 1949. The sediments jeopardize reliable operation of the dam and the 70,000 kW Cresta Powerhouse by obstructing reservoir outlets. The owner has conducted a number of comprehensive studies investigating sediment management alternatives for the reservoir since the mid 1980s. For the EDDY Pump demonstration, approximately 7,833 cubic meters of sandy sediment deposits near Cresta Dani were dredged and returned to the reservoir bottom 600 meters upstream. Turbidity, suspended solids, dissolved oxygen, flow, density of the slurry, and production rate were monitored. It was concluded that the dredge performance exceeded the manufacturer's production specifications and easily complied with restrictive water quality standards. Slurry densities greater than 70 percent solids by weight were sustained, while peaks over 90 percent were achieved. Production rates of over 230 cubic meters per hour were observed. The maximum turbidity of the discharge plume was only 12 Nephelometric Turbidity Units (NTU) over ambient.

Subject Headings: Reservoirs | Dredging | Sediment | Turbidity | Pumping tests | Eddy (fluid dynamics) | Water quality | California | United States

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