Spring finish seen for intake tower at Oregon’s 367-MW Pelton Round Butte

Operators of the 366.82-MW Pelton Round Butte hydroelectric project foresee completion in spring 2009 of a 273-foot-tall underwater intake tower and fish collection station designed to restore fish passage to the Deschutes River Basin.

Project licensees Portland General Electric and the Confederated Tribes of Warm Springs report construction is progressing on the $108 million �selective water withdrawal tower� being built in Lake Billy Chinook above Round Butte Dam in Oregon.

CH2M Hill, EES Consulting, and ENSR/AECOM Technology Corp. designed the tower in collaboration with PGE Engineering. The utility said Barnard Construction Co., Dix Corp., and Thompson Metal Fab are constructing the facility.

The tower and collection facility consist of three sections being constructed on a barge at Round Butte Dam. As each section is completed, it will be floated to the intake site. The project schedule called for the bottom section to be anchored in August, followed in October by installation of the second section, a 40-foot-diameter steel pipe that will connect the bottom intake to the top intake.

The top section, to be installed in December, will feature the fish collection facility and screens that will allow both collection of fish and intake of water for powerhouse generation. Once the top section is in place, an access bridge will be used to anchor the facility to the shoreline and provide a means to transport people, materials, and equipment to the fish collection facility.

PGE Vice President Stephen Quennoz said the new facility would help the utility continue to provide the region with an important source of clean, renewable power while being a good steward of the environment.

Tower operation to mimic natural conditions

The underwater tower is to draw water from the warmer surface layer and from the cooler bottom layer of Lake Billy Chinook. It is designed to modify currents and temperatures to mimic natural conditions and attract migrating fish into the collection facility. It is expected to: lower lake temperatures, providing healthier conditions for fish; modify the temperature of the lower Deschutes River to more closely match pre-dam conditions; and improve water quality in project reservoirs and in the river.

At the fish collection station, the fish will be sorted, with young salmon and steelhead transported by truck downstream below the dams. When they return to the project as adults, fish reaching the lowest dam will be sorted and salmon and steelhead will be transported by truck above Round Butte Dam and released to reach upstream rivers to spawn.

The Low Impact Hydropower Institute selected three-plant Pelton Round Butte project (No. 2030) for certification as �low impact� hydropower in 2007, citing an array of environmental protection measures, including the new fish passage system. (HNN 4/3/07)

The Federal Energy Regulatory Commission issued a 50-year relicense for the project in 2005 that included a number of fish-related measures. The 247.12-MW Round Butte development is one of three powerhouses in the Pelton Round Butte project (FERC No. 2030), the only U.S. hydro project licensed jointly by a utility and a native American tribe. The other powerhouses are at the 100.80-MW Pelton and 18.9-MW Reregulating developments.

Although the FERC-licensed installed capacity for the project is 366.82 MW, PGE said the project’s actual capacity is 465 MW, based on the following individual plant capacities: Round Butte, 338 MW; Pelton, 108 MW; and Reregulating, 19 MW.

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