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1 r 1 1 11 1 r t The first option provides screening of fish before they enter the HPP and bypasses them as safety as possible back to Lake Havasu. This would reduce the mortality of fish now being experienced by entrainment in the pumps. Screening options consisted of, (1) vertical wedgewire screens in either a linear or "V" configuration (or multiple "V"), (2) horizontal rotating drum screens, or (3) modular incline screens. The cost estimate and design criteria were based on the vertical wedgewire screen option using a 2.4 mm slot width, which is not intended to remove small or passive life forms. Smaller slots could be installed depending on the efficiency of the cleaning system. The screens would be installed in the HPP intake channel or in the inlet transition channel. Archimedes Screw or Internal Helical Pumps would bypass the fish back to Lake Havasu. This option would require trashracks, wedgewire screens, baffles, screen cleaning machinery, structures and supports, bypass pipes and/or channels, and the bypass pumps. The major cost items and assumptions are included in Table 1-3. Table 1-3. Cost of Screening HPP at the Inlet Item Cost ($) Mobilization (5%) 1,050,000 Fish Screen Structure (Civil) 9,000,000 Pump-bypass Structure (Civil) 1,500,000 Fish Bypass Pipeline & Outfall 2,000,000 Cofferdams, Dewatering 300,000 Trashracks 500,000 Fish Screens 2,500,000 Baffles 2,000,000 Screen Cleaners 350,000 Bypass Pumps 1,100,000 Subtotal 23,000,000 Unlisted Items (10%) 2,000,000 Contract Cost 25,000,000 Contingency (25%) 6,000,000 Field Cost 31,000,000 The second option would restrict fish from entering the HPP by mounting screens directly on the existing trashracks. This option would require installing the wedgewire screens on the trashracks and providing a trash rake and conveyor system to handle debris accumulation. Debris would need to be elevated and dumped into a debris pit or hauled off site. The slot opening size recommended was 2.4 mm. This would not eliminate entrainment of small life forms. A fish bypass would not be required. The major cost items and assumptions are listed in Table 1-4. Control Structure Feasibility Evaluation Miller Ecological Consultants, Inc., February 18, 1997 1-31