Lower Monumental Dam
by Andy Porter
A power plant on a Lower Snake River dam that started work when Richard Nixon was president took a step toward a new life this month.
On April 7, workers at Lower Monumental Dam lifted the dam's Unit 1 turbine out of its pit, a move that will allow repairs to modernize the facility's 46-year-old hydroelectric plant.
Located south of Kahlotus, Wash., the dam is one of four on the Lower Snake River managed by the U.S. Army Corps of Engineers Walla Walla District office.
Taking the turbine out of its pit was no small task. It is 26 feet in diameter, slightly more than 13 feet tall and weighs 287 tons.
"It has been more than 20 years since Lower Monumental has had a turbine removed so it was a major event for us," said Bryce Thompson, chief of technical services at the dam. "The turbine removal was necessary in order to replace some broken hub linkage pins inside of the turbine that allow the blades to rotate."
The work to upgrade the hub linkage involves the complete disassembly of the turbine runner, installation of internal hub components and reassembly of the runner.
Generator winding replacement and turbine cavitation repairs on the unit are being done by a United States branch of Andritz Hydro, which is headquartered in Vienna, Austria.
The Corps' Walla Walla District awarded a $12.9 million contract to the company in July 2015 for the work on Unit 1 as well as maintenance and winding placement work on the Unit 2 generator.
Gina Baltrusch, public affairs specialist for the Corps, said all six generators at Lower Monumental Dam and the turbines in Units 1-3 were provided by Andritz Hydro's predecessor companies when the dam was constructed in the 1960s. The dam went online in May 1969 and generates 810,000 kilowatts of power at full capacity.
In a release, Jason Williams, project manager, explained the turbine runner is a critical element in modernizing the dam's powertrain. The runner determines the ultimate performance of the powerhouse and sets the stage for other improvements. It also plays a role in allowing fish to pass through the project.
Corps officials said no significant investments have been made to improve the reliability or increase the capability of the generating units since they were installed.
The entire project is expected to be completed by May 2017, Corps officials said.
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