The U.S. Army Corps of Engineers Nashville District and the Tennessee Valley Authority have decided, following a joint risk assessment of the main chamber of Wilson Lock on the Tennessee River near Florence, Alabama, not to reopen the chamber until the phase 2 dewatering is completed.
USACE photo of Wilson Lock. (USACE Nashville District Public Affairs Office)
The repairs needed to restore the chamber to full operational capacity are scheduled for completion in spring 2025.
“The structural damage noted during inspection, particularly to the lower gates and pintle casting, presents an unacceptable risk to both safety and operational integrity,” said Megan Simpson, chief of the Maintenance Section for the USACE Nashville District. “The impact of reopening the chamber on operational performance, structural integrity, and personnel safety would be significant, and the temporary mitigation measures available during the current dewatering window do not sufficiently reduce the risks associated with operating the gates.”
The estimated time for a total replacement of the gates, which would be necessary in the case of a catastrophic failure, is five years or more.
Temporary mitigation measures USACE and TVA evaluated included bracing and repairs to the cracks on the gates. The agencies are still investigating the root cause of the damage to the gates and pintle assembly.
USACE photo of Wilson Lock. (USACE Nashville District Public Affairs Office)
Lt. Col. Robert Green, commander of the Nashville District, said that while the district intends to minimize the impact of the closure on the navigation industry, the risks to continued lock operation and public safety were too great to authorize a temporary reopening.
“Continuing operations with the gates in their current condition could result in a complete failure of the gate or further damage beyond repair,” said Green. “The decision to keep the gates closed reflects our commitment to mitigating these risks and ensuring their long-term operability.”
“A sudden failure of the lower gates could result in extensive infrastructure damage and potentially cause injuries or fatalities,” he added.
Matt Williamson, a lock mechanic with the U.S. Army Corps of Engineers Nashville District, assists fellow mechanic and diver Ty Melton in preparing to go underwater to examine cracks in the gates at Wilson Lock in Florence, Ala., Oct. 9, 2024. The air supply Williamson is carrying is a backup safety measure in case of a failure in the main air supply, which is kept onboard the diving platform and relayed to the diver via the cables attached to his helmet.
Photo by Jeremy Croft
U.S. Army Corps of Engineers, Nashville District
The estimated time for a total replacement of the gates, which would be necessary in the case of a catastrophic failure, is five years or more. By not reopening the chamber early, USACE and TVA hope to repair the damage to the chamber and restore full functionality as efficiently and safely as possible.
Key milestones in the repair timeline include:
• Repairs to the river caisson slot, completed at the end of last week (November 2024)
• USACE-TVA risk assessment, scheduled to be completed in early December.
• First dewatering of the main chamber lower end to inspect and conduct initial repairs to assess the risk of returning to limited operation, scheduled from early November to late December 2024.
• Determining the root cause of the pintle cracking, scheduled to be completed by the end of 2024.
• Second dewatering to replace pintle assemblies and complete repair and stabilization of the gates, scheduled for the first three months of 2025.
• Completion of repairs to the pintle and gates, scheduled to be completed in spring 2025.
“Our goal is to complete this repair as soon as possible while doing our utmost to ensure the safety of our crews,” said Megan Simpson, Maintenance section chief with the Nashville District. “Wilson Lock is a vital component of a navigation system that helps provide economic and hydrological stability to the Tennessee River Basin.”
The Tennessee Valley Authority owns the locks and dams along the Tennessee River and the U.S. Army Corps of Engineers operates and maintains the locks for navigation, in partnership with TVA.
The Nashville District has a longstanding partnership with the Tennessee Valley Authority to operate and maintain navigation facilities on the Tennessee River. More than 65M tons of goods make their way to and from the Ohio River every year through USACE-managed locks on the Tennessee River.
The public can obtain news, updates and information from the U.S. Army Corps of Engineers Nashville District on the district’s website at https://www.lrd.usace.army.mil/About/Districts/Nashville-District/, on Facebook at www.facebook.com/nashvillecorps and on X at www.twitter.com/nashvillecorps.
