OMAHA, Neb. — The Omaha District of the U.S. Army Corps of Engineers awarded a $2 million contract on April 17 for the placement of rip rap along Missouri River Levee Units L-575 and L-550 in southwestern Iowa and northwestern Missouri.
The rip rap consists of boulders that vary greatly in size. They will be placed on the riverward side of the new setback levees constructed earlier this year at the lower and middle breaches of L-575 near Hamburg, Iowa, and the upper breach of L-550 near Watson, Mo., that occurred during the Flood of 2011.
In addition to the rip rap, the contract includes the installation of a filter fabric. Together, these two items form an armoring for the levees that help to reduce the potential of erosion from high river flows and associated wave action.
"The rip rap dissipates the energy of any wave action in the river prior to reaching the levee," said Bret Budd, the chief of the Omaha District Systems Restoration Team. "With that energy reduced, there is less of a chance that the river can erode the river bank into the base of the newly constructed setback levees."
The work is anticipated to be completed by the end of July.
The contract was awarded to Western Contracting Corporation of Sioux City, Iowa.
Following the Flood of 2011, repairs to the breaches at levees L-575 and L-550 were identified as the most critical in the Missouri River Basin. Contracts were awarded for the initial repairs in October of last year with dirt moving soon after. Between three breaches along L-575 near Percival and Hamburg in Iowa and two breaches along L-550 near Watson and Rockport in Missouri, contractors placed 2.7 million cubic yards of material along new setback levee alignments in 86 calendar days. The levees help to reduce but not eliminate the flood risk for those communities behind the structures.
"It is important people realize that there is always a risk associated with living and working behind a levee," Budd said. "These new setback levees restore the level of flood risk mitigation along this stretch of the river to its pre-flood status. And the rip rap will help protect the levees from erosion. But that risk still exists."
In response to the Flood of 2011, the District Engineer for the Omaha District identified a need for a special execution cell or team to engage in time-sensitive rehabilitation of flood controls structures - including dams and levees - in the Missouri River Basin. Drawing on funding provided by the Disaster Relief Appropriations Act signed Dec. 23, 2011, by President Barack Obama, the Omaha District Systems Restoration Team was established to focus the vast skills and abilities of the district to execute an estimated $280 million in repairs on 18 levee repair projects and $234 million on some 100 projects at the mainstem dams and related flood control structures along the Missouri River.
For regular updates on the repair efforts to flood control structures in the Missouri River Basin, visit the Omaha District’s Flood 2011 Repairs Systems Restoration Team web page.