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1 Figure 1-6. Example Fixed Cylindrical Screen Concrete Dam tilled Cylindrical steel pipes f screens Fishway Fish ladder Powerhouse Penstock ' Concrete manifold Attraction flow pipe (Source: Francfort et al. 1994) 1.3.6.2 Plate Characteristics. Fixed plate screens are very commonly used in a variety of applications. A fixed plate screen consists of a standard large size screen panel that may be mounted in several different configurations (Figure 1-7). Fixed plate screens can be either a vertical or near vertical wall of mesh in a straight line or a "V" plan configuration, or set at an incline (i.e., inclined screen) to direct fish upward or downward in the water column to a bypass. This category also includes conventional bar racks used for velocities up to 5 feet per second at waste or/water screening facilities. The inclined screen must have adequate control of the water surface elevation on the screen to assure that the downstream end does not become dewatered, which may in turn dewater the fish and debris bypass. The inclined screen also has problems establishing a uniform flow distribution over the length of the screen. In contrast, the vertical and "V" screen configuration can accommodate a range of flows and forebay water surface elevations with uniform flow over the screen surface (sometimes requiring baffles or vanes on either side of the screen) as long as debris is removed promptly. Mechanical brushing or backwashing is required for removing debris from all fixed plate screen configurations. Typical Existing Applications. The fixed plate screen is commonly used to provide fish screening against turbine entrainment at hydro-power projects. They are especially prevalent in the northeastern and northwestern United States from the smallest flows up to 2,000 cfs. Most applications consist of a single bank of racks placed in front of the turbine intake or intake forebay at a 45 degree angle to flow. Many have been installed for debris exclusion at small hydro-power, water and wastewater projects, and have not been used as extensively for fish diversion. Notable examples were fixed plate screens that have been installed are the North Wasco Public Utility District Hydro Project at The Dalles Dam on the Columbia River, the Eugene Water and Electric Board's Leaburg Hydro Project on the McKenzie River in Oregon, and the proposed large flow, small screen size (0.2 mm) facility at the McCluskey canal diversion in South Dakota. Control Structure Feasibility Evaluation 1-18 Miller Ecological Consultants, Inc., February 18, 1997