Corps Watches Tailwater Level As Wilson Repairs Begin
The regional heavy capacity fleet has arrived at Wilson Locks and Dam, Tennessee River Mile 259.4, to begin dewatering the main lock chamber for repairs aimed at returning it to service in mid-June.
The main navigational lock at the facility in Florence, Ala., has been out of service since September 25, when operators heard popping noises later determined to be cracking. The pintle castings, part of the hinges on which the lower miter gates open and close, are cracked and will be replaced. Inspection crews found multiple cracks in the webbing of both the landside and riverside lower miter gates as well as cracking that extends the width of the bottom girder of one gate, near the pintle casting area. The cracks were not present when the chamber was dewatered in 2022, according to the Corps of Engineers.
Brian Mangrum, chief of the Nashville Engineer District’s technical support branch, said in the weekly videoconference call with industry on March 4 that the fleet was making preparations to set caissons and planned to dewater the chamber March 6-8 as long as conditions allowed. The Corps, with assistance from the TVA Forecast Center, was keeping a close eye on elevated tailwaters below the dam. If dewatering began as scheduled on March 6, it would allow the crew to stay on schedule for completing the repairs, Mangrum said.
If the caissons are overtopped by water, the Corps requires an additional inspection to ensure safety, so if it appears the water could get that high, crews might have to pull the caisson and wait for more favorable conditions, Mangrum said.
The TVA Power Services Shop has completed rough machining of the pintle assemblies, with final machining to take place once the existing pintle assemblies are removed, Mangrum said. Gate support components—essentially bracing—are on target for completion the week of March 10, and they should be shipped to the site toward the end of the week so that installation can begin, allowing access to the pintle area.
“The bottom line is all critical path activities are on target at this time,” Mangrum said.
Additionally, he said, the Corps plans to offer an in-person update for industry and a tour of the worksite March 27. Mangrum expected details to be released within a few days on how to register for the site visit. He said the number of people attending might have to be capped due to space limitations.
Wilson Locks and Dam facility operations supervisor Brian Brewer said he appreciated the patience of those transiting the lock over the weekend of March 1-2 as there was downtime at the auxiliary lock to repair some grease lines and inspect the lower gates. He said there could be delays of four to five hours in the coming days as the heavy capacity fleet offloads equipment.
The Corps of Engineers’ lock queue report showed 35 vessels in queue the evening of March 4, some of which had as many as 15 barges in tow. One standard-sized barge can lock through the auxiliary lock at a time. The queue report showed that some vessels had been waiting to transit the lock since February 16.
