After Congress first authorized it more than 20 years ago, the now nearly $1 billion replacement for the Chickamauga Lock could be operational in November 2027.
The Chickamauga Dam Lock is a chamber used to raise or lower ships between different water levels on the Tennessee River.
To fix structural problems at the facility and provide faster, smoother cargo movement, the U.S. Army Corps of Engineers is building a larger lock at Chickamauga Dam that could accommodate nine barges at a time—eight more than the existing facility. The original structure was built in 1940 and could be decommissioned in 2029.
“We’ve been putting as many patches on the Chickamauga Lock as we can to keep it operational,” said Joseph Cotton, project manager for the lock replacement, during a tour of the construction site Monday.
(READ MORE: Cost of new Chickamauga Lock triples over time)
The facility suffers from a chemical reaction that causes the concrete at the lock to grow, creating cracks and structural problems that Cotton said the Corps and Tennessee Valley Authority have managed to address through years of intensive maintenance. Maj. Jesse Davis, deputy commander of the Nashville District of the U.S. Army Corps of Engineers, said careful monitoring by the Tennessee Valley Authority, the Corps and the agency’s contractors has ensured the dam remains structurally sound.
“Every action we take takes this reaction into account and ensures that the final product is reliable and safe over the long term,” Davis said during a presentation.
Other dams have problems with concrete expansion, but Cotton says it’s a fairly unique phenomenon in the Chattanooga area. A rock called dolomite triggers the reaction, creating a thin gel-like substance that puts billions of rocks throughout the dam under stress. Workers have to account for this at every stage of the construction project and monitor the effects using 3,000 sensors installed along the entire lock and dam.
“The Chickamauga Lock and Dam are really the problem child of the entire system,” Cotton said.
To avoid similar problems in the future, Cotton said the Corps and its partners have been working to find quarries with suitable materials for the lock. Workers are using about 25,000 cubic yards of concrete on the project, Cotton said, which is enough to build a two-lane road from Chattanooga to Clarksville.
The Tennessee Valley Authority built the lock along the Chickamauga Dam in the late 1930s. Today, the Army Corps of Engineers operates the lock and took over maintenance in the 1980s.
More than a million tons of cargo pass through the gates each year, keeping hundreds of large semi-trailers on the move. Last year, 1.3 million tons moved through the facility, Cotton said, and that number could exceed 1.5 million in 2024.
(READ MORE: New Chickamauga Lock in Chattanooga topped with first of 36 monoliths)
The new lock chamber will measure 110 feet by 600 feet, larger than the existing 60 feet by 360 feet, and will reduce commercial transit times by 80 percent and provide access to 318 miles of upstream waterways.
The Corps hopes to award the final contract for the project this fall. Officials estimate the total cost of replacing the lock will be $954 million, with $237 million already allocated in the last federal budget. Due to delays in congressional funding and additional problems with materials and labor, the project’s costs have tripled over the past two decades.
Contact David Floyd at [email protected] or 423-757-6249.
