Power Creek Hydroelectric Project Features
General: The project consists primarily of:
- a diversion dam and intake structure at stream mile 3.3
- a tunnel-and-pipeline power conduit conveying water approximately 5700′
- a powerhouse at stream mile 2.2 containing two 3.0 MW generating units for a total installed capacity of 6.0 MW
- a 7.0 mile long buried and underwater transmission line
- approximately 2.9 miles of access road
Diversion Dam and Intake Structure: The diversion dam is a concrete structure approximately 10 feet high with a crest length of 70 feet. The dam is a concrete sill on the streambed topped by 8 foot high inflatable dams 48 feet long. The forebay level will normally be at elevation 420 and the dam will be lowered during high flows to flush out sediment and debris. The intake structure is 60 feet long with trash racks and a sediment retention wall.
Power Conduit: The power conduit has four distinct sections; 1) a 600 foot long upstream buried pipeline, 2) a 9 foot diameter horseshoe shaped power tunnel approximately 3,000 feet long, 3) a penstock bridge totaling 180 feet and a buried pipeline extending approximately 2,200 feet from the bridge to the powerhouse.
Power House: At the powerhouse a steel manifold will distribute the water flow to two turbines rated 3124 kW each at 280 feet net head. Maximum water flow will be 320 cubic feet per second total for both turbines. The turbines are twin-jet Turgo turbines manufactured by Gilkes. The generators are 400 rpm 3,000 KW units manufactured by Teco Westinghouse. The tailrace is rock lined leading to the right bank of the stream. There is a switchyard to the west of the powerhouse for transformers and circuit breakers.
Transmission Line: The 25 kV transmission line runs for 2.3 miles under Power Creek Road. It then runs under Eyak Lake for 4.7 miles to near CEC’s Eyak Substation where the voltage is stepped down to tie into CEC’s Eyak Substation.
Access Roads: Three permanent access roads have been constructed; 1) the 1,100 foot powerhouse road, 2) the 1,850 foot tunnel portal road, and 3) the 12,300 foot intake road.