The road over Beaver Lake Dam, closed for a couple of weeks twice this summer to facilitate repairs, was reopened last weekend after the head gate was removed and transported for rehabilitation and repair.
Operation Manager Sean Harper of the U.S. Army Corps of Engineers (ACE) said that during the Memorial Day weekend the bridge was open to one-lane traffic to accommodate visitors, with a temporary light system that coordinated movement.
“We wanted to have one lane of traffic over Memorial Day so there was as little inconvenience as possible for folks over that holiday,” Harper said. “It worked flawlessly and I think really helped. It wasn’t the most convenient, but it was better than having the road completely closed.”
Beaver Dam houses two hydropower plant units for generating electricity. A 20-ft. diameter pipe, called a penstock, delivers water down to the runner that spins the generator. Harper said the work involved maintenance of what they call a head gate, a bulkhead that can be lowered in front of the penstock to prevent water from being in the tube.
“The head gate is a heavy metal structure with seals that basically has been in the water for fifty years,” Harper said. “This is the first time it’s had major maintenance done. The gate is twenty-seven feet tall and twenty-two feet wide. It weighs 237,000 pounds. We had to close the road for a crane big enough to pull the head gate up. That’s why the road closed a few times over May and early June.”
Eight bulkheads have been put in place to take the place of the head gate while it is off being restored. The bulkheads stacked one on top of each other like a stack of dominoes. Harper said the last work to be done before finishing up would be to remove those bulkheads.
There are two head gates in the dam, and workers will probably rehab the other later in the summer.
Harper said that once the head gate is repaired and new seals installed, it would be ready to fulfill its function for many years.
“This maintenance is good for the continuing life of the hydropower plant,” Harper said. “It was generally in pretty decent conditions for being fifty years old. It just needed some rehab.”
There was some concern from the public about the road being closed, particularly people who weren’t expecting it and had to detour back to US 62 to get where they were going. Harper said they received suggestions on road signs, which they purchased, to give people earlier notice about the closure.
Work is being performed by the Tennessee Valley Authority. Harper said the first time TVA worked on the project, they weren’t able to get the gate removed.
“It was the first time it was done on Beaver Dam, so the first effort wasn’t enough to get the job done,” Harper said. “So, they made a second trip up and got it completed.”
There had been rumors that the ACE was planning to drastically lower the level of the lake in order to facilitate dam repairs.
“That rumor seems to be fairly common,” Harper said. “It’s something we hear every year. We have not made any adjustments to lake levels to facilitate any maintenance. So far, no drawdowns have been implemented to facilitate the work. It would have been easier if we had drawn down the water. The parts of the work in the water were accomplished with divers.”
Harper said news releases would be sent in advance of closing the road when it comes time to reinstall the rehabbed head gate, which is in two to three months. The road will be closed again when the second head gate is removed to undergo the same treatment. Harper wasn’t sure of the timing.
“We will know more as we get closer to doing the second head gate repair,” he said.