LOCATION
Tennessee River Mile 471 in Chattanooga, Tennessee
PROJECT DESCRIPTION AND BACKGROUND
The replacement lock project consists of a new 110-foot by 600-foot lock to be located riverward of the existing 60-foot by 360-foot lock and downstream of Chickamauga Dam. A new lock is required at Chickamauga Dam because of structural deficiencies of the existing lock resulting from physical expansion of the concrete structure. This phenomenon of concrete growth was observed soon after initial construction in 1940 and is caused by a reaction between the alkali in the cement and the aggregate. Even with significant maintenance efforts, this expansion threatens the structural integrity of the existing lock and limits its life.
Replacement lock construction began in 2004 with highway and utility relocations and continued through 2012 with the completion of the cofferdam structure and prefabricated components (miter gates, culvert valves, culvert bulkheads, and approach wall beams) that are currently being stored at other Tennessee Valley Authority (TVA) facilities until needed. After a temporary suspension of construction activities due to funding constraints with the Inland Waterways Trust Fund (IWTF), funding returned to the project in FY15. Like all locks on the Tennessee River, the existing and proposed locks are owned by the TVA but operated and maintained by the Corps of Engineers.
The new lock is vital to maintain 318 miles of navigable channels upstream of Chickamauga Lock and Dam to support stakeholders including the Department of Energy at Oak Ridge, Tennessee, TVA, and numerous other businesses. The current Chickamauga Lock can pass one “Jumbo” barge at a time and the new lock will allow nine barges to pass at once.
CURRENT STATUS
- Chickamauga Lock’s current risk based total project cost estimate is $954.4 million (FY23 price level); approximately $569 million has been expended through December 2024. Estimated project completion is February 2031.The 2023 TPCE indicates an additional $236.8 million is required for project completion and is under review with expected updates in March 2025.
- The $309 million Lock Chamber contract was awarded Sep. 28, 2017; it is currently 78% complete based on payments and has a required contract completion date of Jan. 27, 2026. Miter Gates have been delivered to site and will be installed through 2025. The contract will result in a completed navigational lock located inside the cofferdam. Projected contractor completion is June 2026.
- The $68M Upstream Approach Wall (USAW) contract was awarded Sept. 9, 2021 and has a projected contractor completion of November 2025. The Upstream Approach Walls allow vessels to safely navigate in to the new lock without being impacted by flows going over the Chickamauga Dam spillway and will feature a tow haulage system that will contribute to the greater efficiency of the new lock.
- The award of the Approach Wall and Decommissioning (AWD) contract is planned for August 2025 with an in-service date of February 2028.
- The project’s total Benefit to Cost Ratio (BCR) at a 7% discount rate is 1.0 and its Remaining Benefit to Remaining Cost Ratio is 2.0 At the FY23 discount rate of 2.75%, these Ratios increase to 1.8 and 3.8, respectively. An updated TPCS is under development.
AUTHORIZATION
Consolidated Appropriations Act of 2003 (P.L. 108-7); reauthorized in America’s Water Infrastructure Act of 2018 (P.L. 115-270)