Although the Tennessee Valley Authority is moving forward on a permanent solution to its flood control sand baskets at Tellico, Fort Loudoun and other local dams, completion of the Fort Loudoun project is still a few years out, with work not scheduled to be wrapped up until after the conclusion of the Tennessee River bridge project that will replace the existing bridge over the dam.
TVA Spokesman Jim Hopson said a majority of the flood control work has already been completed as TVA installs concrete structures and raises earthen berms to increase dam protection in the event of a catastrophic flood. Adding the remaining sand baskets, however, has been delayed and will not be replaced until after the new Tennessee River bridge is complete, Hopson said.
“Work is being delayed to a certain extent by the ongoing U.S. (Highway) 321 project because we don’t want to get in and interfere with that project to work with these ... barriers,” Hopson said. “We are coordinating with the Department of Transportation there for Tennessee in order to get that converted over as quickly as we can without more dramatically impacting the motoring public in the 321/444 interchange.
“It’s very possible that those may not be completely changed out until after the 321 project is complete,” he added. “Again, we are trying to be very conscious of the further impacting and already difficult traveling situation because of that construction.”
Gene Phillips, who lives near Fort Loudoun Dam, said that regardless of the delay, he doesn’t see the real purpose of the flood control project.
“They are preparing for a flood that may come in 1,000 or 10,000 years from now, and we’ve never had one since the dam has been built or even in history like they say may come, and I think it’s just a waste of taxpayer’s money,” Phillips said. “It would actually be going over the dam, I believe, before it would ever get up to where they have those sand bags.”
But that’s not his only concern.
“It looks ridiculous,” Phillips said about the aesthetics of the area. “What it does, it blocks off all the beautiful view that you used to be able to see when you came across the dam.”
Results from an environmental impact study on permanent dam safety modifications found that probable maximum floodwater elevations at four local dams, the theoretical worst type of flooding that could occur in the area, are higher than previously calculated, according to a TVA report, hence the reason for implementing the flood control measures. In addition to Fort Loudoun and Tellico, TVA is also making changes at Cherokee and Watts Bar dams.
“For our area that is essentially multiple days of multiple feet of rain that would eventually fill up all of the upstream reservoirs and eventually overtop the existing earthen embankments,” Hopson said. “The reason we are creating these higher areas there is we are creating a higher embankment so that we are creating a larger barrier. It’s not a case of where we are concerned about water overtopping the concrete portion of the dams themselves. It’s the earthen embankments that tend to be the abutments to either side of that concrete portion that we are most concerned about because if water were to continually overwash those earthen embankments it could create an erosion problem which would cause the entire embankment to fail.”
Hopson said TVA hopes to further water prevent from overtopping those embankments.
“But let me be clear that probable maximum flood conditions don’t even exist in the geological record for eastern Tennessee,” Hopson said. “It’s the theoretical worse that could possibly happen.”
In 2009, TVA implemented temporary and permanent measures at the four dams to remain consistent with federal dam safety guidelines, to comply with nuclear plant operating regulations and to minimize the potential effects of the PMF. The modifications consisted of installing stone-filled barriers, also called sand baskets, at the four dams and strengthening the downstream embankment of Watts Bar Dam.
Permanent solutions to those sand and gravel-filled baskets include a roller-compacted concrete, Hopson said.
