Nashville District awards contract to rehabilitate three Center Hill Dam hydropower units
June 26, 2014
By Bill Peoples
NASHVILLE, Tenn. - The U.S. Army Corps of Engineers Nashville District awarded a $47,257,431 contract yesterday to Voith Hydro, Inc., to rehabilitate three hydropower units at the Center Hill Dam Powerhouse in Lancaster, Tenn.
According to Jeff Linkinhoker, project manager for the rehabilitation project, this acquisition will rehab, repair, and modernize the three turbine-generator units that went into operation between 1950 and 1951, which will ensure reliable future hydropower generation and green energy in the region.
"The expected life of this type of equipment is between 30 and 40 years," Linkinhoker said. "All of the turbine-generator equipment and most of the supporting peripheral equipment is original. The units are now over 60 years old and are showing their age. Units of this age become less reliable and produce less power, which is especially important during times of peak electricity demand."
Voith Hydro, an international corporation, has been in business for more than 140 years supplying a full-line of hydropower equipment to countries all over the world, including high profile projects at the Robert Moses Niagara Power Plant on the Niagara River in Lewiston, N.Y., and Three Gorges Dam on the Yangtze River in China. The company has offices in the United States located in Tennessee, Oregon, and Pennsylvania. Voith's previous experience with the Nashville District included rewinding generators at the Wolf Creek Dam Power Plant on the Cumberland River in Jamestown, Ky. The contract award announcement is available on the Federal Business Opportunities web site at https://www.fbo.gov/index?s=opportunityba2c9800bd618f958f19d8e956706261781dd8133093fc181f47c3b8294e362b677720507bec56c81ffba857d6eb28181c75debd34b75386856f71bf55e30909mode=formba2c9800bd618f958f19d8e956706261781dd8133093fc181f47c3b8294e362b677720507bec56c81ffba857d6eb28181c75debd34b75386856f71bf55e30909id=87fbcb3c4a3d635ae6350c32c594a4b7ba2c9800bd618f958f19d8e956706261781dd8133093fc181f47c3b8294e362b677720507bec56c81ffba857d6eb28181c75debd34b75386856f71bf55e30909tab=coreba2c9800bd618f958f19d8e956706261781dd8133093fc181f47c3b8294e362b677720507bec56c81ffba857d6eb28181c75debd34b75386856f71bf55e30909_cview=1.
The contractor will supply all labor, materials, and supplies to tear down and reconstruct the turbine-generator units using modern technology. The construction work will include, but not be limited to, replacement of turbine runners, replacement of wicket gates, refurbishment of servomotors, replacement of generator stator windings, restacking of existing generator stator cores, installation of vibration monitoring systems, installation of high pressure thrust bearing oil lift systems, and reconstruction of unit braking systems.
The disassembly and assembly of generator rotors weighing 200 tons each require the use of an overhead bridge crane to remove and replace the heavy equipment. The 14-foot diameter turbines, although not quite as heavy as the rotor assembly, must be precision machined and balanced to spin at over 100 revolutions per minute. The turbines will be cast and machined to close tolerance before being installed.
A condition assessment of Center Hill's turbine generators performed in the 1990s by the U.S. Army Corps of Engineers Hydroelectric Design Center in Portland, Ore., reported decreased turbine efficiency because of the age of the units.
In 2004 the Nashville District signed its first Memorandum of Agreement with the Southeastern Power Administration and power customers to provide a funding stream to rehabilitate 28 hydroelectric generating units located at nine hydropower plants operated by the district in the Cumberland River Basin. The Water Resources Development Act of 2000, Section 212, authorized the Corps to accept and expend a portion of this revenue 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 in the Cumberland River System. Over the life of the program SEPA looks to direct more than $1.2 billion into the Cumberland River System Hydropower Rehabilitation.
"All of the units were placed in service between 1948 and 1977," said Jamie James, a professional engineer and Section 212 Program manager for the Nashville District. "All of the plants have continued to perform past the normal 35-year design life, but suffer from equipment failures that can cause unplanned outages and reduce efficiency and reliability."
James said the water that flows in the Cumberland River Basin is potentially used multiple times to generate electricity as it passes through the hydroelectric power plants along the river from Wolf Creek Dam in south central Kentucky along the Cumberland River through Tennessee and to Barkley Dam in western Kentucky.
"The fuel is free, clean to acquire, produces no carbon emissions and is restocked each time it rains," James said.
Linkinhoker added that hydropower-generated electricity has positive environmental benefits when compared with electricity generated from burning fossil fuels.
"Fossil fuels such as coal, oil and natural gas emit carbon dioxide into the atmosphere, contributing to global warming," Linkinhoker added. "Hydropower is considered to be a green source of electricity since it depends upon rainfall - a renewable, non-polluting resource."
Auto venting features will be incorporated into the design of the new hydropower turbines at Center Hill Dam. This technology will introduce air into the water as it flows through the turbine and will result in elevated dissolved oxygen levels in the water released into the Caney Fork River. This will benefit the aquatic resources of the Caney Fork including the trout fishery.
The Nashville District is pleased to undertake this rehabilitation of the Center Hill Dam Power Plant - the first of nine rehabilitations in the Cumberland River Basin to help meet the nation's demand for electricity while also benefiting the environment.
(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.)