Chickamauga Lock Replacement, Chattanooga

The concrete at Chickamauga has been growing since the 1940s, and that is the whole reason this project exists. Alkali-aggregate reaction has been expanding the 1940 lock chamber for decades, squeezing the gates and driving maintenance costs that no amount of patching fixes. On February 13, 2026 the Army Corps of Engineers Nashville District awarded the last contract in the replacement program, a $192.1 million package to C.J. Mahan Construction Company that carries the new lock across the finish line.

Project Scope

The replacement chamber is 110 feet wide by 600 feet long, built alongside the existing 60-by-360-foot lock at Tennessee River Mile 471. Mahan’s scope covers the downstream approach walls, breaching the existing dam to tie in the upstream approach, commissioning the new lock, and removing the cofferdam that has protected the work site. The upstream approach wall was roughly 70 percent complete when the contract was let. Total program cost runs to about $1 billion, funded through the Inland Waterways Trust Fund and the Bipartisan Infrastructure Law.

Why It Matters

A tow that needs nine jumbo barges through Chickamauga today makes multiple cuts, breaking the tow apart and reassembling it on the other side. The new chamber takes all nine 35-by-195-foot barges in a single lockage. The Corps puts the efficiency gain at roughly 80 percent, and for shippers moving grain, aggregate and manufactured goods on the upper Tennessee it changes the arithmetic of barge versus truck on a stretch of river that serves Chattanooga, Knoxville and the industrial corridor between them.

There’s a second reason the work matters. Chickamauga is one of a handful of inland navigation structures where the failure mode isn’t wear, it’s chemistry. The concrete is expanding on its own schedule. Every year the replacement slipped, the Corps spent more on gate adjustments and emergency repairs to keep a 1940 chamber operating past its design life. Awarding the final contract puts a date on the end of that.

Project Team & Details