Locks and Dams

Two Years After Guidewall Sank, Delays Mount At Wilson Lock

Tows are waiting an average of 13 to 15 hours to begin locking through Wilson Lock on the Tennessee River, more than two years after remnants of a hurricane sank a floating guidewall.

Average lock processing time has also risen—to an average of approximately seven hours, with outliers of 10 hours—according to analysis by the Tennessee Valley Authority and the Corps of Engineers. That means that, depending on what time of day it arrives, it might be possible to complete locking through only one tow a day in the winter or possibly two during the summer.

Information about the delays was provided in a presentation by Nikki Berger, TVA navigation program supervisor, and brought out in subsequent discussion at the 57th annual meeting of the Tennessee River Valley Association (TRVA) and the Tennessee-Cumberland Waterways Council October 9-10 in Franklin, Tenn.

“I know it’s still causing a lot of hardship for the navigation industry,” Berger said of the delays, noting both financial burdens and safety issues.

While TVA has been providing a helper boat at the site, located at Tennessee River Mile 259.4 in Florence, Ala., downbound lockages can only take place during daylight hours, a problem that compounds as winter approaches and the days shorten, Berger said. Some tows have waited as much as 24, 36 or even 48 hours in total at the site.

An interim solution to the problem has been devised but will also take time to put into place, Berger said.

“The goal is to restore normal operations at the lock,” she said.

The plan involves positioning a series of three large, interlocking spud barges of the type usually used for work on the ocean. The barges would be oriented to engage at least 10 or 11 of the 12, 120-foot spuds, driving the spuds into the riverbed to create a temporary, floating lock approach wall. Analysis of the solution was tested using modeling with the Corps of Engineers’ Engineering Research and Development Center (ERDC) in Vicksburg, Miss. A TVA project approval board voted to purchase the barges in August, and a purchase order was issued in September following review by a second board, Berger said. Vessel Repair Inc. of Port Arthur, Texas, which built the mv. Freedom for TVA, is building the barges after winning the bid to do so.

Construction is slated to begin in January or February 2024, and the barges will take roughly a year to build, and then must be transported and installed, meaning the interlocking wall of spudded down barges is projected to be in place in fall 2025, Berger said.

The spud barges are not designed to withstand current impact loads, but they should at least equal the impact loads of the original floating boom wall, Berger said. The upper wall, which was in use more than 60 years, detached from lock monoliths and sank to the bottom of the river August 31, 2021, as the remnants of Hurricane Ida moved inland, causing 6-foot waves that penetrated hatch lids that were not fully secured. It is still on the bottom of the channel, 80 feet down, and it would remain there when the spud barges are brought in unless determined to be in the way, Berger said.

While the spud barges are believed to be a temporary solution, it is not in TVA’s business plan to permanently replace the wall, she said, noting that the agency received rough funding estimates of $80 million to $100 million or more, given supply chain difficulties and inflation.

“We don’t have the funding for it,” she said.

The original structure was funded by congressional appropriations, but TVA is unable to receive appropriations. TVA has been working closely with the Corps of Engineers, which could receive appropriations, however, Berger said.

“We are seeking funding for that permanent solution,” she said.

Those in the audience asked if extra spuds will be on site if any get bent over by the force of tow impacts. Berger said there is no plan for that, although the Corps estimates only seven to eight spuds are required to be engaged for the wall to work as intended.

Considering the depth of the river at the site, a floating replacement wall would make more sense than a traditional wall as a permanent solution, TVA believes. However, any permanent replacements would need to meet today’s design standards.

Cline Jones, TRVA executive director, noted the importance of funding a permanent solution to the region.

“It’s something we really have got to find a resolution to and get moving on,” he said.

Besides the lock’s importance to regional navigation and the bottlenecks at the site, he noted that a fully functioning inland navigation system is key to national security. Parts for nuclear generators must move through the lock as they are too large to travel by truck, he said.

Additionally, United Launch Alliance transports Atlas V and Delta IV Heavy boosters, second stages and payload fairings through the lock. ULA is also scheduled to move the next-generation Vulcan Centaur rockets via the river to meet launch demands for the U.S. government’s National Security Space Launch (NSSL) program for use by the United States Space Force and U.S. intelligence agencies for national security satellite launches. The rockets and associated parts move from ULA’s manufacturing facility in Decatur, Ala., through locks on the Tennessee River before moving down the Ohio and Mississippi rivers and across the Gulf of Mexico to the launch site in Cape Canaveral, Fla., or to Vandenberg Space Force Base in California.

“We’ve been two years and two months without a solution,” Jones said. “For two years, we’ve been kind of wrestling this bear.”

Jones said TRVA is working with TVA, the Corps of Engineers, legislators and anyone who might be able to help provide funding for a permanent replacement, but that it is taking time. He continues to draw attention to the problem, hoping that will help.

“We just need to get that thing replaced,” he said. “Yesterday.”