Pelton Round Butte Selective Water Withdrawal Project Wins ACEC Award
Project engineer CH2M HILL accepted the award with client PGE at awards gala
CH2M HILL announced that the Pelton Round Butte Selective Water Withdrawal Project has won the American Council of Engineering Companies’ (ACEC) national Grand Award. The Pelton Round Butte Hydroelectric Project is co-owned by Portland General Electric (PGE) and the Confederated Tribes of the Warm Springs Reservation of Oregon. The award was accepted by PGE and CH2M HILL, who provided design and construction oversight for the project, at ACEC’s 2011 Engineering Excellence Awards Gala on April 1 at the Grand Hyatt in Washington, D.C.
Located near Madras, Ore., on Lake Billy Chinook, the original Round Butte dam, built in the early 1960s, affected water flow and temperature so greatly that native salmon and other fish could not find their way out of the reservoir, and natural migration ceased. In 2004, in an agreement with the Confederated Tribes of Warm Springs of Oregon, PGE hired CH2M HILL to complete a fish collection and bypass system at the three-dam, 465-MW Pelton Round Butte Hydroelectric Project in order to restore the anadromous fish runs to their natural habitat.
After thorough and complex evaluations, CH2M HILL designed and helped construct the Pelton Round Butte Selective Water Withdrawal Project, which, completed in 2009, is the only known floating surface fish collection facility coupled with power generation in the world. As a result of the selective water withdrawal project, the Pelton Round Butte Hydroelectric project has been certified by the Low Impact Hydropower Institute as a source of green power. The project was designed to modify the surface current directions to improve guidance of the migrating fish into the fish collection structure, provide a fish sorting and handling system, exclude all fish from passing through the turbines and ensure the water passing through the turbines complies with the state and tribal water quality standards in order to restore water quality to improve the fish habitat. For the first time in 40 years, Chinook, sockeye and steelhead salmon are able to complete their life cycles as the juvenile fish are passed downstream to the Deschutes River basin and then are able to return as adults to spawn naturally upstream of Round Butte Dam. More than 100,000 fish were captured and transferred downstream in 2010, its first full year of operation.
The design of the 270-ft-tall steel and concrete structure was significantly influenced by the complex construction challenges and site staging limitations, and 3-D modeling was integral in developing the engineering data and material quantities. The largest construction challenge was assembly, lowering and attaching the equivalent of a six-story building to the face of the existing power intake that was submerged 270 ft in water. With virtually no room on the crest of the dam, a pontoon barge with central moon pool was used for assembly, and the structure was designed so that remotely operated submerged vehicles could perform nearly all of the underwater work. Other challenges included the underwater excavation of nearly 200 cubic yards of solid rock without blasting, drilling eleven 30-in.-diameter rock sockets each about 30 ft deep, the installation of 1,100 ft of 24-in.-diameter steel pipe piles and the placement of nearly 200 cubic yards of high-strength underwater grout. All work activities were completed with minimal impact to daily power generation.