TVA, Corps work to reopen lock after barge accident
Locking through a dam is a routine occurrence for those who ship thousands of tons of goods by barge up and down the Tennessee River system. But the situation at Wilson Dam and Lock was anything but routine on the morning of August 3.
A barge traveling to Decatur, Alabama, got too close to the upstream gate of the lock chamber. As the chamber was filling with water, the bow of the barge caught the bottom of the gate’s edge. As the water level continued to rise, the barge lifted the gate from its normal position in the gate slot. One end of the gate rose nearly all the way out of the lock. The other end shifted slightly and then jammed into the gate slot, resulting in damage at both ends.
“To make matters even worse, the barge was carrying xylene, a hazardous chemical used to manufacture polyester fiber,” said Ray Jordan, TVA Police Commander. “Because of the potential hazard to the surrounding communities, the local emergency management office activated its command center where each of the responding organizations helped to develop the recovery strategy.”
The first priority was to ensure the integrity of the barge and its cargo. After determining the barge was not leaking, engineers from TVA and the U.S. Army Corps of Engineers developed a plan to remove the barge from under the 210-ton gate. A decision was made to secure the gate in place and then slowly drain the lock to lower the barge and free it from the gate.
Crews installed a temporary water barrier upstream of the lock and then worked to place steel below the damaged gate to hold it up as the barge was floated safely down and away from it. A large floating crane was used to remove the gate and set it on a barge for delivery to TVA’s Power Service Shops in Muscle Shoals.
With the main lock out of service, the Corps, which operates the lock, faced a major traffic jam. Tows were backed up for miles both upstream and downstream of the lock.
After the barge and towboat involved in the accident were removed from the main lock chamber, the Corps was able to open the small auxiliary lock at the dam. After the damaged gate was removed, a special watertight structure, called a caisson, was installed so that the main lock could be used for daytime barge traffic.
“The caisson has worked well, but it is only a temporary fix,” said Jim Davis, Mid-Tennessee River Operations Manager for the Corps. “It has to be lifted and lowered by a crane on a barge, so it isn’t suitable for nighttime or extended use. But it’s allowed us to keep commercial river traffic moving, and that is our top priority.”
TVA crews are working around the clock to repair the gate and return the main lock to service as quickly as possible.
“Because this is the first time we have removed a lock gate to make repairs, it’s taken a lot of planning and teamwork, said Power Service Shops supervisor Ricky Posey. “With ironworkers, fitters, electricians, laborers, and a crane operator on each crew, the repair process is actually going a little faster than we thought it would.”
The main lock was closed most of October for routine inspections and repairs, as previously planned. It reopened to daytime traffic on Oct. 30. The Corps expects the lock to resume full operation in late November or early December.
Davis explains the push to expedite the project with these statistics: “About 1,500 commercial tows lock through Wilson Dam annually, carrying about 12.5 million tons of goods. To carry just 15 barge loads by truck, you would need 900 tractor-trailers. That not only explains why the repair work is on a fast track, it also illustrates how vital, cost-effective, and environmentally beneficial shipping by water can be.”