JOHNSON CITY, Tenn. (WJHL) — The seven-year-long multi-million dollar repair project Boone Dam appears to have worked.
That’s the word from the Tennessee Valley Authority, the owner and operator of the hydroelectric dam built in 1952 near the Sullivan and Washington County, Tennessee line.
“Every indication we have right now it is performing just as we intended,” said Chris Saucier, TVA’s Boone Dam technical director. “Which is the greatest news.”
And that’s true not only for TVA staff assigned to the project. They know it’s the greatest news for the hundreds of property and business owners around Boone Lake who’ve endured years of frustration.
In October 2014, a sinkhole near the base of the dam followed by what TVA calls “muddy discharge” coming out of an embankment downstream alerted engineers to a potentially serious problem — possible internal erosion, the leading cause of dam failures.
Seven years and almost $300 million later, TVA said the final “structural repair element” on a soaring cutoff wall embedded in the earth dam was installed on January 13. Critical testing is now underway with TVA holding Boone Lake at the same level as when the sinkhole appeared.
“The correlation between what we expected to happen and what we’re seeing is so high that we’re really confident things are going to go well for the rest of the test period,” Saucier said.
If all goes as plan — and it’s clear TVA engineers expect it will — Boone Lake will increase in depth incrementally until mid-July when it will reach “full pool” depth where it will remain until the regular winter drawdown with a return to its regular summer level next year.
“While we had it down, we decided to fix it once and fix it right,” said Boone Dam project manager Sam Vinson. “So we had a lot of confidence coming into this spring.”
When testing ends at the end of May, TVA plans to construct a concrete floodwall on top of the dam and begin restoring the area around Boone Dam from a construction site to a public use area. The visitor’s center will be re-opened, parking lots will be replaced, and the popular beach at Boone Dam will be re-opened to the public around Memorial Day weekend 2022.
The scope of the Boone Dam repair project and TVA’s investment in the repair and restoration effort is hard to grasp. The agency says it’s spent about $290 Million so far to shore up the dam. TVA says 215 people at times worked around the clock on the multi-phased repair project, the centerpiece of which is the new concrete wall in the middle of the earthen portion of the dam that’s 900 feet long and, in places,178 feet tall.
“So now you have a concrete section running through the center of the embankment to hold water seeping through and keep it from continuing to unravel the soil,” Vinson said.
Six years ago this July, TVA broke the news about the sinkhole and the concerns about possible internal erosion at Boone Dam. That concern was so great at the time that TVA rapidly dropped Boone Lake by 30 feet in late October into early November 2014 to take pressure off the dam. It happened so fast that boats became stranded on freshly exposed lake bed. Within just a few days, expensive lakefront property lost its prized direct access to the water. And many Boone Lake Marinas were marooned, devastating the small business owners who had almost no warning.
As the project nears completion, the Boone Dam project manager acknowledges the pain felt by the public while insisting that the process was the right thing to do.
“We could have ignored the repair and left the lake down 30 feet and it (Boone Dam) would have been stable,” Sam Vinson said. “But TVA decided (fixing the dam) was the right thing to do, not just for the community but also for the economy.”
Vinson said he believes TVA’s high standards for the repair will ensure Boone Dam’s safety for years to come.
“We expect it to be around for generations,” he said.