Repair work at Boone Dam remains on schedule to be completed by July 2022, but lake water levels are expected to approach normal levels next summer, TVA officials said Thursday.
Water levels are expected to fluctuate over the next 12 months as work on a separate 2-foot-wide wall is completed and water is raised to test the efficacy of repairs, TVA officials said during an online public webinar.
Lake levels were lowered six years ago after an inspection revealed seepage issues in ground near the dam. The $450 million repair project, which includes constructing the wall, is underway.
The wall is to be comprised of 307 cylindrical elements called sinking piles that are 50 inches in diameter and 120 to 175 feet deep, spaced between 31 to 35 inches apart, TVA’s manager of civil construction projects Kevin McMillion said.
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“Of the 307 piles needed to form the cutoff wall, 250 are now complete. The remaining 57 will be completed over the next few months,” McMillion said. “Once that is complete, we have to complete the verification [testing] program. … The last activity is the final construction and completion report.”
Reservoir levels are expected to approach more normal levels in spring 2021 and resume normal operations in July 2022, Technical Project Manager Chris Saucier said.
The lake is currently at 1,352 feet and is scheduled to rise to 1,360 next month and then gradually rise to 1,373 next May. Between May and July, water levels are to go to 1,382 feet, which is near the normal summer level prior to the drawdown for construction.
“This is a target elevation. … What we’re doing, we’re not attempting to get to normal operations next year,” Saucier said. “What we’re really doing is testing the performance of the construction we just built — this wall through the embankment. [We’re] seeing how well that will be responding to changes in pool [depth], and we’re also evaluating changes in the groundwater pool around the dam to establish a new baseline because basically what we’ve done with this wall is create a new dam.”
The temporary beach area will be underwater next year and not be available for public use, due to the water level fluctuations, Saucier said.
In preparation for increased water levels, TVA continues to address vegetation issues, McMillion said. TVA crews mulched 900 acres during the past year, and another 525 acres were sprayed with an EPA-approved aquatic herbicide. Work is expected to continue well into 2021.
“We plan to cut along main access channels, around coves and docks in high-traffic areas. We will have crews with pole-mounted chainsaws working to cut vegetation around docks on [the] main channel as well as docks in coves,” McMillion said. “We will continue working by ground as ground conditions allow and continue working from barges in areas we cannot get equipment to by ground. … Late spring and throughout the summer [2021], as the reservoir levels begin to rise, crews will continue working from barges collecting floating debris and removing it from the lake.”
Most of the cutting is expected to be completed by next spring, McMillion said, but could resume next fall if needed.