The turbine in hydropower unit two at Center Hill Dam saw the light of day for the first time since 1950 last week when it was lifted out for replacement.
Replacement of the 82-ton steel turbine, also known as a "Francis Wheel" is one of the first steps in the rehabilitation of all three of the dam’s hydropower units, as well as those on all nine dams on the Cumberland River, Loren McDonald, project manager and assistant program manager for the Nashville District Section 212 Program, told the Review.
"Section 212 allowed money from the production of electricity that would normally go into the treasury to be brought back into the program for the rehabilitation of the units on the Cumberland River," McDonald shared. "The Center Hill major rehab is the first such project, but there is a master plan to rehab all nine dams, a total of 28 generating systems, in the Cumberland River system. No major rehab has taken place before, so we are going to be replacing equipment that is well beyond its 35-40 year design life. The project will result in all the power plants being reliable for a minimum of 50 years." 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.
Jeff Linkinhoker, project manager for the U.S. Army Corps of Engineers Nashville District, said the reason the generators have outlived their expected lives was due in large part to exemplary maintenance.
"This dam, (Center Hill) is 65 years old and has never been rehabbed," Linkinhoker told the Review. "A lot of the credit for that goes to the operations division for the way they have maintained the plant. I often say they love these generators the way an auto mechanic loves his 1957 Chevy. They have been meticulous in the way they have cared for the units over the years. An assessment of all the plants was done a few years ago, and with Center Hill being one of the older facilities, it was determined that it would be done first. Today we are replacing the turbine rotor in unit number two. It will be replaced with a stainless steel unit that is superior to the original. The new unit will include a system that aerates the water as it spins. In order to do that now we have to spill or sluice, so the new design will be much more efficient, and we won’t need to waste any water by spilling or sluicing."
The Corps’ Nashville District awarded a $47.25 million contract to Voith Hydro in June 2014 to rehabilitate the hydropower units at Center Hill. Work began in July and work on unit two is scheduled to be completed in the fall of 2016. Unit one is next in line for rehab, then unit three will follow. The project is expected to be complete in three years.
Jeffrey Flowers, power plant project manager for the Nashville District Mid Cumberland Area, told the Review that the project at Center Hill will cost approximately 63 million dollars.
"The rehab project will cost around 63 million dollars for all three generators," Flowers said. "They will be completely rehabbed and rebuilt to the same standards that they were originally, with a few improvements. These generators have had a few small issues over the years, but no major repairs. I attribute that to the way they were originally constructed, as well as the way they have been taken care of. We have a great maintenance program, but after 65 years it is time to replace them."
The nine dams on the Cumberland River produced 2.7 billion kilowatt-hours of electricity and about $57 million dollars in revenue for the U.S. Treasury in 2014. Each of the three generators at Center Hill produces enough electricity to power 12,000 homes. The three hydropower units at the dam can supply a city of 125,000.