Repairs at 100-year-old Alabama dam speed up barge traffic on the Tennessee River

Source | A U.S. Army Corps of Engineers crew has completed work on damage to the gates at 100-year-old Wilson Dam in the Shoals that caused delays of commercial barge traffic on the Tennessee River.

“Between the repairs to the minor gates and the installation of the floating wall, it’s a big win for the commercial navigation industry,” said Brian Mangrum, chief of the Corps of Engineer’s Nashville district technical support branch. “It allows us to go back to completely normal operations in passing traffic through the lock.”

How long were the delays at the dam which will have been in operation for a century for commercial traffic on Friday? Some commercial traffic was delayed for 21 days, said Shane Carman, manager for river services for the Tennessee Valley Authority, which operates the dam.

“Once we got it opened up, there’s been zero delays,” Carman said. “Traffic is back up and flowing.”

To get traffic flowing at a normal pace, a Corps of Engineers floating crew lifted the lower minor gates, which weigh 1.3 million pounds.

“Once the gates were lifted, we got access to components that needed to be replaced,” Mangrum said. “We also installed some additional bracing. That’s going to help keep that structure stabilized as we’re moving forward until they can be replaced or rehabbed in the future.”

Once the gates were lowered and the floating wall was installed, the locks were reopened. According to officials during a visit by U.S. Rep. Dale Strong, R-Monrovia, to the dam in the spring, the project cost $18 million.

While the main lock was being repaired, barges used the auxiliary lock, which had been in operation since the dam opened. Lt. Col. Robert Green with the Corps of Engineers said last spring what normally was a two-hour barge lift in the main system took as long as 24 hours with the auxiliary system.

More than 3,700 vessels a year pass through the lock carrying 11.4 million tons of cargo. The dam plays an important role in national security and space industry travel with the United Launch Alliance rocket plant in Decatur and the Lockheed Martin missile plant in Courtland just a few miles downriver.

While the gates to the main lock were being repaired. TVA used its tugboat Freedom to help ULA transport four components of its Vulcan rocket last spring over a period of eight days, Carman said.

“We were delivering one component at a time,” Carman said. “We would load the components in Decatur. We would meet up with the ship. It would take us about three hours.”

Freedom, a 35-foot-wide, 100-foot-long boat that weighs about 500 tons, helps TVA move its big assets such as nuclear generators, transformers and turbines and clears debris out of the bottom of rivers near hydro facilities.

Other work at dam

Work at the dam is not limited to repairing damage to lock gates. TVA is in the process of refurbishing other parts of the dam, which was in operation before the utility agency was formed in 1933. Some of the components, including turbines, that were in use when the facility opened are still in use.

“It is amazing that after 100 years, the basic design of the dam has not changed,” said Jimmy Springer, assistant plant manager.

The dam has 21 units, eight of which date back to when it opened.

“Unit 3 is down, it is being completely disassembled as part of our hydro life extension program,” Springer said. “They will tear all of the components out of this unit from the turbine wheel all the way up to the top of the generator. They’ll inspect the major components to see if they are in good enough shape to last for the next 40 or 50 years, anything that is not will be replaced with new equipment … at the same time, we are integrating new technology.”

The dam’s 21 units can produce 663 megawatts. That’s enough to power 380,000 homes and businesses, Springer said.