WOUNDED FLUME

TVA provides repair update

By AUTUMN HUGHES

Posted 2/8/18

It’s been three months since a rockslide damaged the Tennessee Valley Authority’s Ocoee Flume, causing the shutdown of the Ocoee #2 power house and a halt to power generation at the facility. However, officials expect this week to begin removal of the original fallen rock debris along with additional rocks that were brought down as a precaution.

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WOUNDED FLUME

TVA provides repair update

Posted

It’s been three months since a rockslide damaged the Tennessee Valley Authority’s Ocoee Flume, causing the shutdown of the Ocoee #2 power house and a halt to power generation at the facility. However, officials expect this week to begin removal of the original fallen rock debris along with additional rocks that were brought down as a precaution.

“The slope (above it) was the first thing we were worried about,” TVA Ocoee Plant Manager David Falls said on a visit Wednesday to the broken section of flume.

To make sure no more rocks would break off and tumble toward the flume and the workers, Falls said rock totaling approximately three times the original slide was brought down. Areas of the cliff face that were considered “suspect” were either brought down or reinforced so they are less likely to fall, he added.

According to Falls, workers have also been busy getting in place the materials needed to begin work on the flume, among those the lumber to build structures for the workers who will remove the fallen rocks and rebuild the flume.

Basically, the flume is a 14-foot-deep trough with wooden sides and floor that has delivered water to the TVA power house for more than 100 years. The flume’s walls and the floor are comprised of tongue-and-groove Southern yellow pine lumber boards 3 inches thick by 8.5 inches wide. Some areas along the five-mile length have safety decking so that passengers can get out of carts that run on a rail system, otherwise the flume is open at the top.

A rail like a train track runs the length of the flume, carrying passengers, materials and equipment across the top of it.

The flume is five miles long and the rockslide occurred about a mile from the Ocoee # 2 power house.

Falls said approximately 40 feet of the flume was damaged. He added work was done on the flume in the 1980s. Because the flume is on the National Register of Historic Places, it must be restored to “historic standards.”

“We can’t change the look of it,” Falls said.

Falls said on Nov. 8, 2017, one large rock fell on the flume and it had to be broken into more manageable pieces so it could be moved.

“We worked on it until right before Christmas,” Falls said, adding contractors began working on-site on Jan. 8.

Falls said there is a $1.4 million budget for the project, which should be completed in “early to mid-May.”

“It should be done before the recreation schedule starts,” he said.

Falls noted the discovery phase of the rockslide’s aftermath is continuing.

“We don’t know how much damage has been done underneath the rock,” Falls said he is still worried “to a point” about more rock slides.

If more damage is discovered as the fallen rocks are removed, it “could pose a risk to schedules and budget,” he said.

However, if nothing new is found during the discovery period, crews will begin construction next week.

Tom Davis is the contractor manager for the project. He said on Wednesday the original slide “was one huge slab of rock.”

Falls said long metal pins and bolts were used to secure suspect areas of rock adjacent to the slide area.

“We’re going to be up here for several months,” Falls said.

There are safety challenges and physical challenges to the work because the location is hard to reach.

“It’s cut out of a ledge on the side of a cliff,” Falls said of the worksite.

TVA had to get large enough equipment in place to work on the flume, which caused additional concerns: The steep, narrow access road leading from the power house to the flume access was damaged by the heavy equipment that had to be driven up the hillside.

Also, part of the covering of the flume at the access area near the power house was removed so that the heavy equipment, like bulldozers and trackhoes, could be lifted by crane and placed inside so that they could be driven within the flume to the worksite. When the work is done, they will have to bring down all the equipment, which will pose additional concerns.

Falls said workers “haven’t actually started moving rock yet” and with the recent rain they had to postpone building shelters for the workers at the worksite. He added the number of workers on the site will vary each day as laborers are working to move fallen rock and then carpenters will be brought in to build the shelters. After that the heavy equipment operators will be on-site as the flume reconstruction begins.

Falls said the work will be done by G•UB•MK Constructors, an unincorporated joint venture offering a broad range of construction capabilities to TVA.

Falls was actually driving along Highway 64 the morning of the rockslide and saw where the flume had broken and water cascading down the mountain.

Scott Fiedler with TVA Public Relations said Falls notified TVA and “we saw it on social media at the same time. It was really amazing to see.”

Falls said he knew immediately there was a problem when he saw mud in the Ocoee River, then he saw the water spewing from the broken flume section. He called a technician to shut off the Ocoee #2 diversion dam and stop water going to the flume.

Falls said the flume is inspected weekly and there are sensors along it to monitor the water level and alert to any issues. However, he saw the physical damage and initiated shutdown before he even had a chance to see the alert system in action.

He said workers have used this down time to work on projects like trash rack maintenance – this is the device used to filter trash from the water. Also, a planned outage was scheduled for June but officials moved it up to do the maintenance while the flume is out of operation. Falls said crews are also working on some safety projects at the diversion dam area.

While the flume is currently out of commission, Falls said a low level of water is maintained in the flume so the wooden boards remain swollen and sealed against leaks.

When the repair work is completed, Falls anticipates the power house will resume power generation at its previous rate of 19 megawatt hours.

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