KINGSPORT, Tenn. — Repairs to Boone Dam remain on track to be completed by May 2021 with Boone Lake returning to normal operation in July 2022, Tennessee Valley Authority officials said Friday.
Boone Dam Project Manager Sam Vinson and Senior Manager of Civil Construction Kevin Holbrook, both with the TVA, gave an update on the project and vegetation clearing on Friday. Not much has changed with the repairs since May when the last on-site update was given, but Vinson and Holbrook said work is ramping up for more significant progress to be made in the coming months. That is to include construction and installation of the cutoff wall in the earthen embankment of the dam, which is the final phase of repairs.
The reason for the 14 months between the completion of construction and when the lake will return to full summer pool is for testing of the wall and restoration of the dam area.
Home and business owners will be given 60 days notice before levels are fluctuated. Lake levels will be raised and lowered during that time to ensure the wall will hold, for construction infrastructure that was built to be removed and for the dam crest to be restored to its original height and width before it was changed to meet repair needs.
Boone Lake was lowered to winter pool levels — 30 feet below summer pool — in October 2014, so the cause of sediment seepage at the dam could be investigated. Since then, the lake has remained at those levels, exposing 1,400 acres of the lakebed, where vegetation, including trees, is growing.
After a monthslong investigation, TVA officials determined that the earthen embankment of the dam will be repaired by placing a composite seepage barrier, or a cutoff wall, under the embankment and grouting — the process of injecting grout, a mixture of rock, cement and water — into the dam. Grouting is complete.
TVA officials gave a five- to seven-year estimate for completion in 2015. The project is still within its $450 million budget with $170 million spent so far, Holbrook said.
Last September, TVA announced it would be mulching hundreds of acres of the vegetation, which later was determined to be 512 acres, Vinson said Friday. TVA set aside $2.1 million for the mulching, which isn’t coming out of the budget for the dam repairs, with 35% spent so far. More than 130 acres were added to the list by request of landowners and have been mulched so far with at least an additional 30 acres to be mulched over the next month, Vinson said.
Vegetation growing on the lakebed and the timeline of the repairs has frustrated homeowners, business owners and recreationalists throughout the duration of the repairs. Some landowners don’t want the vegetation cleared because it boosts the viability of fish health and population, Vinson said.
“Everything from songbirds to rabbits, deer — it’s a good habitat in this transitional period, and then when the reservoir comes back it’s a big player in fish health,” Vinson said. “The reservoir shrunk; the fishing here became phenomenal — same amount of fish in a smaller body of water so it was shooting fish in a barrel. At some point, we all are ready for this lake to get big again — it’s the same number of fish so there has to be a beneficial environment for that fish population to recover very quickly.”
Four hundred acres of native grasses have been planted on the lakebed to prevent erosion and for the benefit of animals, Vinson said.
Much of the lake bed is privately owned so TVA has to ask for permission to clear vegetation. Landowners have the option to opt out of what’s been dubbed the supplemental vegetation management plan and others that weren’t on the initial list can opt in, but there are limitations including rocky or soft soil areas that the forestry mulchers can’t access.
The focus of the vegetation mulching is in narrow areas of the lake, not the more accessible and wider part of the main channel, Vinson said.
“What we were trying to supplement, help the property owners with, was what we consider sloughs … these are more narrow; some of them are heavily or densely populated with boat docks,” he said.
Some of the areas are reached by water with the mulchers being brought in and unloaded off of a barge. It was never an option to hand cut vegetation because of the inefficiency of it, Vinson said.
Mulching will cease in early October and will begin again in February through at least next September. The same areas cleared this year will be reassessed for more mulching.
Because the dam and lake areas are rich in history and culture TVA continues to work with East Tennessee State University’s archeology department to identify and protect cultural sites, Vinson said. Since the lake was lowered, 96 new sites have been discovered including the foundations of historic farmhouses, pre-Civil War and Native American artifacts and evidence that the Overhill Cherokee lived in the area 300 years before originally thought dating back to the 15th century, he said.