Evaluation of turbine intake modifications at Bonneville Dam second powerhouse, 2002

In 2000, the U.S. Army Corps of Engineers conducted hydraulic model studies to evaluate flow in the second powerhouse intakes at Bonneville Dam. As a result of these evaluations, three modifications were proposed to increase upward flow toward the intake gatewells: 1) Increase the size of the vertical barrier screen (VBS) by removing a portion of the concrete beam below it. 2) Install a turning vane below the picking beam on the submersible traveling screen (STS). 3) Install a gap-closure device on the intake ceiling downstream from the top edge of the STS. In addition, to meet new design criteria for salmonid fry established by NOAA Fisheries, screen mesh openings on the new VBS were decreased to reduce impingement of fry. Contract no. W66QKZ80545753