Kentucky Lock Addition Downstream Cofferdam

This project on the Tennessee River consisted of the construction of a cofferdam downstream of the Kentucky Dam to facilitate the addition of a new 1,200-foot lock landward of an active 600-foot lock. The major scope of work was the construction of a concrete monolithic wall used for the temporary cofferdam and a permanent component of the new lock chamber. Johnson Bros. Corporation manufactured a custom gantry crane on barges to hoist ten precast concrete shells up to 46.5 feet wide by 54 feet long by 33 feet deep and weighing up to 1.5 million pounds into place. The shells were then filled with concrete, and the wall was extended 24 feet vertically utilizing the cast-in-place methodology.
The scope of work also included underwater overburden excavation and weathered rock removal by mechanical means, monitoring and dewatering of the upstream previously constructed phase, demolition of a portion of the existing lock wall, and electrical work. The project surroundings included environmentally sensitive areas, swift currents, low-lying high voltage electrical lines directly above the work area, and a high volume of commercial barge traffic. Kentucky Lock is identified as the most utilized navigation lock in the USACE’s Great Lakes and Ohio River Division.