The Mississippi River Levees Construction Project (MRL-C) is a subset of the overarching Mississippi River and Tributaries (MR&T) Project, authorized by the Flood Control Act of May 15, 1928. The goal of the MRL-C project is to manage flood risk along the Mississippi River by conveying the Project Design Flood flows through the Mississippi Valley to the Gulf of Mexico.
The project features reduce the risk associated with riverine flooding by raising and strengthening existing levees to provide protection against a project flood having a flow of 3,030,000 cubic feet per second passing the Old River Complex. Without corrective actions to address the identified deficient levee reaches the system will not operate in accordance with the project design, introducing significant risk to the 1.9M residences behind the existing levees.
The Carrollton Phase III reach of the MRL-C project represents one of the most critically deficient reaches in the entire system (MRL-C Regional Risk Ranking #2). This 3,000’ reach is deficient to the required design grade of 24.5’ with an overtopping maximum height deficiency of 5’ for 500’. Deficiencies in other areas of the reach range from 2’ to 5’. Impacts for construction of this reach of the MRL-C project are covered under the 1998 SEIS.
A number of alternatives have been considered to bring this reach to the required design elevation including multiple floodwall alignments and an earthen levee enlargement. The earthen levee enlargement alternative has been deemed unacceptable due to the availability of sufficient real estate and the severe impacts to utilities, the existing railroad, and operations at the MVN District Office.
Floodwall alignment 2 (behind the MVN District Office, along Leake Avenue) was deemed unacceptable due to constructability concerns attributed to the existing railroad/utilities and the required floodwall height (greater than 10’). Alignments 1, 1A, and 3 are shown below:
Recommended Plan Continued
While estimated construction costs are lower for alignment 1 and 1A, they lack protection to critical MVN District buildings (warehouse, shops, and child care facility) and would require a combination of traditional and deployable/removable floodwall construction in select locations. Alignment 3 is the least disruptive to utility relocations, however this alignment would also require bank stabilization. At this time, alignment 1 is the recommended plan, but each alignment is currently being reevaluated and a final recommendation is scheduled for Fall 2018.
Solicitation is anticipated for Summer 2019, with a construction completion date of Summer 2022