By Scott Robertson
The Boone Dam repair project is proceeding on-time and on-budget, despite challenges created by the COVID-19 crisis in the first half of 2020. Tennessee Valley Authority Principal Project Manager Sam Vinson told a semi-annual news conference the utility plans to meet its final deadline of July 2022, and is also on pace to meet shorter-term deadlines between now and then.
“COVID-19 has dominated the first two quarters of 2020 and for us it was no different, so early in March TVA and our construction and engineering partners began preparing prevention plans,” Vinson said. “We put together multiple contingency plans to make sure we keep the critical work at the dam progressing.”
Following CDC guidelines, TVA has not had a case of COVID-19 onsite. “Many of our work activities have changed a bit, but we have not lost any time due to COVID-19,” Vinson said. “Not only have we not had a case, but we were able to maintain, and in some cases even increase, production on the repair project.”
That’s because the team has stuck to its original priorities, Vinson said. “We stress every day the safety of the downstream public, the safety of the workers and the quality of the repair itself.”
“We have a whole lot of safety checks and quality verification checks that go into the work,” Vinson said. “As of Friday, we had worked more than 1.5 million hours onsite without a lost-time incident.”
TVA uses a network of around 200 monitors to do real-time self-checks within the dam. “We use ‘real-time’ in this industry a lot, but it’s literally on a 15-second recurring update. So, every 15 seconds, we know exactly what the pressure is at multiple points across the dam.
“The second type of instrument (used for real-time measurements at the dam) is called an inclinometer, and as you can imagine, it’s about inclined planes or shifts, so it would measure any movement of the soil or rock that’s associated with the dam.
Site restoration is due to start in May 2021, Vinson said. “That’s everything from putting the beach back to putting the public restrooms back to taking out the infrastructure we have put in and putting the top of the dam back.
“Once we have the site restoration – the crest restoration – complete, we’ll turn the project over to dam safety for reservoir fluctuations next spring,” Vinson said. “They will do a series of fluctuations within the normal operating guide curve.”
In the meantime, the actual construction work continues apace. Vinson said 154 of the planned 307 secants in the cutoff wall are in the ground with work underway on 53 more in stages from drilling to casting concrete.
As for the vegetation that’s been growing on the exposed lakebed, TVA is once again running mulching equipment over several hundred acres, as it has done in past years. This year, TVA is using herbicides on areas where mulching equipment cannot reach. Vinson said the two herbicides being used have both been registered for water use for more than 15 years.