LANCASTER, Tenn. (Oct. 7, 2015) – Work crews lifted a turbine out of hydropower unit two at Center Hill Dam today, one of the final pieces of the disassembly process. It is the first time the 82-ton steel wheel has seen the light of day since its installation in 1950, a rare sight that makes it possible to inspect, rebuild embedded parts, and then reassemble the unit with new components.
Jeff Linkinhoker, project manager for the U.S. Army Corps of Engineers Nashville District, said the exciters and 248-ton rotor were removed about two weeks ago, followed by the generator shaft, wicket gates, basically everything from top to bottom, culminating with the turbine runner.
“It’s exciting when you get to this point. Disassembly of these major components shows real progress,” Linkinhoker said.
He noted that a tremendous amount of work over the past several years led to the milestone of removing the turbine, which included design work and the preparation of the project’s plans and specifications, getting all of the funding in place, contracting work, and a lot of coordination with the contractor.
“A lot of work has gone on behind the scenes. It is how we got to the point where we are now,” Linkinhoker said.
The Center Hill units have a type of reaction turbine runner known as a “Francis” wheel where water is introduced causing it to spin.
Jeff Flowers, power project manager for the Nashville District Mid Cumberland Area, said the turbine runner is one of the last major components of the unit to be removed. The last major component to be removed is the generator stator.
The turbine is a critical component that actually transfers water energy to mechanical energy, and then to electrical energy, Flowers explained shortly before crews lifted it out of the hydropower unit.
“When that turbine turns it turns a shaft that turns a magnetic field that produces the 13,800 volts that the generator produces,” Flowers said. “This is the first time a turbine has been removed in the Nashville District.”
Each hydropower unit at Center Hill Dam supplies enough electricity to power 12,000 homes, which reduces the cost of electricity during peak periods of the daytime. The three hydropower units at the dam can supply the needs of an average city of 125,000 people. Electricity is marketed by the Southeastern Power Administration and then sold to the Tennessee Valley Authority and other preference customers in the region.
The Nashville District awarded a $47.25 million contract to Voith Hydro in June 2014 to rehabilitate three Center Hill Dam hydropower units. The contractor mobilized to the dam in July 2015 and the rehabilitation of unit two is scheduled for completion in the August-September timeframe of 2016. Unit one will then be rehabilitated followed by unit three. It will take three years to complete the project.
Martin Parker, site manager for Voith Hydro, said when the disassembly is completed his team can focus on the next step.
“We’ll start on the rehabilitation of the unit, which is blasting and painting, machining embedded parts, and then rebuilding the generator, which will take a few months, and then we’ll get into the reassembly,” Parker said.
The Nashville District operates nine multi-purpose projects in the Cumberland River Basin, which produced 2.7 billion kilowatt-hours of electricity in 2014. In the same year, sales of this electricity yielded about $57 million dollars in revenue for the U.S. Treasury.
Loren McDonald, project manager and assistant program manager for the Nashville District Section 212 Program, said the hydropower unit at Center Hill Dam is the first of 28 units at nine projects that will be rehabilitated over the next 20 years.
“We’re all very excited to see the first turbine,” McDonald said. “We’re all very happy this will become a common occurrence as we are able to go through the units one by one to rehab the system and increase the reliability.”
The Water Resources Development Act of 2000, Section 212, authorized the Corps to accept and expend funds from power preference customers to perform rehab work on hydropower equipment. Under this provision of the law, funds that would normally be returned to the general fund of the U.S. Treasury are now available to maintain the hydropower generating equipment. Over the life of the program SEPA looks to direct more than $1.2 billion into the Cumberland River System Hydropower Rehabilitation.
Center Hill Dam is located on the Caney Fork River and contributes to the electrical power supply of the area through the generation of clean, safe and efficient hydroelectric power.
(The public can obtain news, updates and information from the U.S. Army Corps of Engineers Nashville District on the district’s website at www.lrn.usace.army.mil, on Facebook at http://www.facebook.com/nashvillecorps and on Twitter at http://www.twitter.com/nashvillecorps. The public can follow Center Hill Lake on Facebook at http://www.facebook.com/centerhilllake)