Contractors Tour Holt Lock, ‘Temporary Fix’ Progressing
The Mobile Engineer District held an industry day September 4 at Holt Lock and Dam on the Black Warrior River in Tuscaloosa, Ala., to discuss the plan to repair a cracked and unstable monolith that led to the lock’s emergency closure more than two months ago.
Holt Lock, which closed to navigation June 22, is located at Mile 347 on the Black Warrior River. The lock, one of three structures within a 30-mile stretch of the river, opened to navigation in 1966 and offers a 64-foot lift.
The affected monolith is on the river side of the lock chamber and supports the lock operator’s office, with the machinery room just below. Officials with the Mobile District had been aware of cracking within that monolith for the better part of a decade, but, in late May, lock personnel noticed significant changes.
“When you see new cracks in old structures, you know something’s going on,” said Anthony Perkins, operations project manager for the Black Warrior-Tombigbee Waterway.
Corps officials say the cracks in the concrete connect back to the fill culvert that runs through the base of the monolith. Cracking runs all the way from the culvert to the top of the monolith, some 150 feet from top to bottom. There’s also a related crack that runs horizontally through the monolith, some 60 feet from side to side.
The Corps and contractor R&D Maintenance are working on a temporary repair, which involves installing a bulkhead in front of the problematic culvert, essentially sealing it off from the upstream pressure of the river. Corps officials hope that will stabilize the monolith and raise the safety factor from 0.5 to above 1, which would allow the lock to reopen to navigation.
Nelson Sanchez, operations division chief for the Mobile District, said R&D Maintenance is on track for a September 30 completion of the bulkhead installation. After that, the Corps will conduct a stability analysis to assess the safety factor for operating the lock. Sanchez estimated that should take five to 10 days.
“There is a potential that it may not work,” Sanchez said, speaking during a September 4 waterway stakeholders conference call. “If that’s the case, then we have to go back and start thinking what do we need to do to get to that factor of safety. Meanwhile, the permanent fix, we’re not going to see any construction of that until probably January or February.”
Sanchez said, as of now, “We’re feeling good,” but there’s no way to know for sure about the safety factor until after the bulkhead installation is complete. Ideally, the lock will return to normal operations.
“Or we may have to alter operations, like daylight hours only or things like that,” he said.
After the temporary fix, the Corps will pivot to a permanent or long-term fix, which will involve installing post tension anchor rods, both vertically and horizontally, to essentially sew the monolith back together. Scott Ellzey, the project manager for the permanent repair, said that effort, from start to finish, could take the better part of a year.
Close to a dozen contractors registered to participate in the September 4 industry day, with around 30 representatives in attendance. Corps officials provided a project overview and facilitated a group discussion in the morning, followed by a lock tour. The site visit included a view of the machinery room, which is experiencing ongoing water intrusion connected to the cracks in the monolith. Potential contractors came back to the lock in the afternoon for breakout sessions, or one-on-one meetings with Corps officials.
Details of the contract are available at www.sam.gov by searching for W9127824R0116. According to the industry day announcement, the estimated cost for the permanent repair at Holt Lock is between $25 million and $100 million.
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Photo caption: Anthony Perkins, operations project manager for the Black Warrior-Tombigbee Waterway, speaks to contractors in the machinery room at Holt Lock during a September 4 industry day. (Photo by Frank McCormack)
