Priest Rapids Dam: Design of a Dedicated Water Supply for the Right Bank Fish Ladder

摘要

A 66-inch diameter pipeline operating at velocities up to 38-feet per second, regulated by an eccentric plug valve, and terminated in a 19-port energy dissipating manifold has been designed to meet the need for an independent attraction water supply (AWS) for the right bank fish ladder at Priest Rapids Dam. This new AWS was requested by fisheries agencies during planning to satisfy an article of Grant County Public Utility District’s (District) new license. The new license was issued by FERC in April 2008, and allows the District to operate the 955 MW Priest Rapids Dam on the Columbia River in central Washington State. The District, Jacobs Engineering, Oakwood Consulting and IIHR-Hydroscience & Engineering formed a team to develop this independent AWS. The team found a potential pipe route using existing penetrations in the upstream face of the dam. Four tools were used to create a design which satisfied the operational requirements for an independent supply: a hydraulic grade line model, a 1-D numerical mixing model, a CFD model, and a 1:10 scale physical model. Use of the 1-D mixing model allowed experimentation with a number of configurations without building them in the physical model. An iterative process was required as the output of each model influenced the inputs of the other two models. This approach streamlined design and resulted in time and cost savings. The final design balanced economics, operational longevity, and effective energy dissipation proven by a calm water surface in the AWS pool. High pipeline velocities and low pressures required inclusion of turning vanes in all elbows. CFD simulations were used to assist design of the elbows. Included in the final project package are a trashrack and structure which meet fisheries criteria, a knife gate guard valve, a plug valve and electric valve actuators to allow remote operation of the system. Construction and testing are scheduled for 2013 which will meet the project completion deadline of April 2014.