Hydraulic Model Evaluation of the Eicher Passive Pressure Screen Fish Bypass System

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bypass, chinook, coho, delayed mortality, Eicher screen, fish bypass, fish passage, fish protection, horizontal, hydraulics, impingement, model studies, mortality, passive pressure screen, rainbow trout, salmon, descaling, screens, smolt, steelhead, trout, water velocity, wedgewire, wedgewire screens

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Palo Alto, CA


Electric Power Research Institute


A hydraulic model of a passive pressure screen fish bypass system was evaluated at the University of Washington Harris Hydraulics Laboratory, Seattle, during 1984 and 1985. Stainless steel wedgewire screen inclined at 10.5, 16.5, or 30 degrees to horizontal, was tested in a Plexiglass conduit. Velocity profiles were measured by pitot tube traverses. Dye tracers were also released to visually track the streamline patterns. Fish were monitored by video camera and recorder as they passed through the pressurized model. The screen angles, water velocities, and screen types were varied. Scale loss was evaluated for smolted fish contacting the screen. Species tested included rainbow trout (Salmo gairdneri) and smolts of coho salmon (Oncorhynchus kisutch), chinook salmon (O. tshawytscha), and steelhead trout (S. gairdneri). Scale loss did not occur to coho, chinook, or steelhead smolts which contacted the screen. No delayed mortality was observed within 72 hours after testing. All fish were successfully passed when velocities through the model were maintained at greater than 5 feet (1.5 m) per second. Small fish (fry size) passed through the model more swiftly than larger ones. Rainbow trout were used for impingement tests over a range of test section velocities from 3.0 feet (0.9 m) to 10 feet (3 m) per second Impingement was predictably produced or avoided by manipulation of velocities, and was most prevalent at test section velocities under 4 feet (1.2 m) per second. Variations in the velocity vector perpendicular to the screen did not affect fish passage over the range tested of 0.4 to 3.0 feet (0.1 to 0.9 m) per second. http://www.epri.com

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