C150324 feas study - Laserfiche WebLink

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Ridgway Reservoir Micro-Hydro Project Loan Feasibility Page 8 of 42 megawatts (MW) and associated mechanical and electrical equipment to generate approximately 22,600 megawatt-hours per year of electrical energy. Releases made from the dam for downstream irrigation and water supplies will also be used for power; the District will not alter its current operation to any significant degree for purposes of hydropower generation. Facility Arran e�ment The facility will use the existing outlet works from the reservoir intake to the bifurcation near the existing gatehouse. The powerhouse will be located downstream (north) of the current outlet far the 24-inch low-flow outlet, which is also north of the main stilling basin. This location is required because it is not possible to build the facility's draft tubes in a manner that would clear the existing low-flow outlet, which is entrenched in the west bank of the stilling basin. The cost estimates are based on two horizontal Francis turbines set approximately 5 ft above minimum tail water in a powerhouse with concrete foundation. Dewatering will be required only for the turbine draft tube discharge, which will extend approximately 15 ft below minimum tail water elevation. The generator will operate at 4,160 volts. The building will be equipped with a monorail hoist for machine assembly and disassembly. The powerhouse will contain features including the following: an overhead hoist for periodic maintenance of the turbine and generator, with a removable hatch in the powerhouse roof; a�re protection system; heating, ventilating, and air conditioning equipment; lighting and communications equipment. Water Conveyance Features A new pipeline will be added to the 54-inch leg of the bifurcation and installed east of the current gatehouse and stilling basin. The new pipe will convey river releases (water supply, irrigation, and low flow) into the powerhouse. A butterfly valve will be installed upstream of the turbine, providing isolation to the facility for maintenance and emergency operations. During normal turbine operations, the existing gate valves on the river outlet works will be closed, forcing flow at the bifurcation to enter the new pipe towards the turbine. After the water passes through the turbine, it is discharged back to the Uncompahgre River only a short distance downstream. In case of an unplanned shutdown, system controls will cause the gate valves to open and the butterfly valve to close, ensuring continued water supply for downstream demands. Water leaving the powerhouse will enter a stilling basin designed to slow the water velocity. The power house stilling basin will be lined with riprap to prevent erosion. An earth or concrete- lined tailrace will be constructed to convey water away from the powerhouse to the Uncompahgre River. Riprap at the confluence with the river will prevent bank erosion and channel degradation. The existing valves and stilling basin will be left in place to provide for operations during times when the turbine is not operating. The existing system will be operated for a short time annually as part of routine maintenance. The facility will produce an average of approximately 22,600 megawatt-hours of energy each year. This production is based on historic releases from the dam to meet irrigation and other demands downstream. The District does not plan to significantly alter its release patterns or schedules to accommodate greater production of energy.