Posted on September 5, 2023
New Orleans, La. – The U.S. Army Corps of Engineers, New Orleans District, awarded a $34.2 million contract to McMillen, Inc. of Boise, ID for construction of a steel system to allow dewatering of the Old River Low Sill Control Structure. Dewatering is scheduled to occur in late summer and fall of 2024 when the river is traditionally at low water stages.
“By keeping the Mississippi and Atchafalaya rivers on their current courses, the Old River Control Complex infrastructure is critical to both the region and the Nation,” said Col. Cullen Jones, commander to the New Orleans District. “This effort to inspect and repair the Low Sill structure will help ensure the integrity and successful operation of the complex for years to come.”
USACE will dewater the Old River Low Sill Control Structure to inspect submerged project features, to conduct subsurface investigations of the foundation material and to undertake any needed rehabilitation or maintenance work. This effort will be the first dewatering of the structure since repairs and modifications were undertaken in 1987.
The Old River Control Complex, located in Concordia Parish, Louisiana, is operated daily to maintain a 70/30 distribution of flows between the Mississippi, Red, and Atchafalaya Rivers and prevent the Mississippi River from changing course to that of the Atchafalaya River. The Old River Control Complex consists of the Low Sill, Overbank, and Auxiliary Control Structures. During the 1973 Flood, the Old River Low Sill Control Structure was severely damaged when a large scour hole formed on the upstream approach and beneath the gated portion of the structure. Emergency repairs during the flood prevented the structure from collapsing.