Southeast Des Moines, Southwest Pleasant Hill, Iowa
Project is in operation. Red Rock Remedial Works protects Southeast Des Moines/Southwest Pleasant Hill (SEDM/SWPH) from the back up effect of the Red Rock reservoir during large magnitude floods. The remedial works also provides a flood protection benefit for the cities from the Des Moines River (DMR). During the Flood of 2008, several deficiencies were discovered with these structures. The SEDM/SWPH levee is physically and hydraulically connected to the Des Moines I system. The levee system protects much of the city's critical infrastructure, including: City Hall; Police Station; regional sewage treatment facility for cities within the Des Moines area; the Greater Des Moines Generating Station; a regional Verizon Communications hub; the Magellan Pipeline petroleum storage facility, which is the largest in Iowa and considered by the Department of Homeland Security as a strategic point of business. The value of the protected area could exceed $1 billion. Flooding of these areas would result in extensive flooding of neighborhoods and commercial/industrial areas that could cause serious contamination of Red Rock
Reservoir. Downstream from here the Des Moines River is a primary source of drinking water for the city of Ottumwa. Approximately 600,000 people would be impacted by the flooding throughout the Des Moines levee system. The economic; disrupted energy production and distribution; and environmental disaster is nearly incalculable, if not incomprehensible.
In 2010, the city of Des Moines and other agencies requested a study to evaluate impacts of increased flood risk identified in the 2010 Des Moines River Regulated Flow Frequency Study (DMRRFFS). The results of the DMRRFFS show that flow frequencies have increased and that floods like 1993 and 2008 are more likely than Corps’ previous estimates from the 1950’s. As a result, the entire levee system protecting SEDM/SWPH are inadequate to protect the city against a 100 year flood. In 2015 the city and MVR initiated a feasibility study to evaluate a variety of flood risk management measures to restore the level of protection. The feasibility study was discontinued in 2016 because a favorable cost benefit ratio could not be realized to justify a federal interest.
The city and MVR are cooperatively working to resolve many outstanding issues through the Corps' 408 process. In addition, other outstanding major issues with the SEDM/SWPH levee include a scour in the DMR adjacent to the SEDML floodwall that could threaten the structure; a deteriorated concrete apron protecting the bank below the floodwall where cracks, spalls and broken concrete lend the structure vulnerable; seepage and piping concerns through levee and pump station foundation materials that could undermine the pump station; an inefficient and inadequate railroad levee breach closure along the flashy Four Mile Creek. A flash flood through the breach in 2010 caused damages to area businesses and industries. Project authorities may need to be modified to satisfy a long-unresolved levee modification and permit shared operating and maintenance responsibilities that were formalized in joint operating agreements in 1972. These were deemed necessary for both parties as the Red Rock Remedial Works was by design a hybrid of a federal and a local flood protection projects.
It had the "advantage of combining a remedial works project with a local flood protection project at a lower over-all cost than the sum of the costs for the separate projects" (Design Memorandum No. 23). Completing the projects described above, restoring the flood protection to a minimal 100 year level, and providing the means for the City of Des Moines to expeditiously complete the 408 process would hasten Des Moines and Pleasant Hill efforts to complete the Southeast Connector—a major transportation artery from the heart of Des Moines to the beltway encircling the Des Moines metropolitan area.
Senators: Charles Grassley (IA), Joni Ernst (IA)
Representatives: IA-2 (Dave Loebsack), IA-3 (Cindy Axne)
Flood Control Act of 1938; Public Law 75-761
Summarized Project Costs
|Estimated Federal Cost
|Estimated Non-Federal Cost
|Estimated Total Project Cost
|Allocations Prior to FY 2020
|FY 2020 Allocation
|FY 2020 Total Capability
Major Work Item Current Year
FY 2020: Develop Plans and Specs to repair SEDM/SWPH Flood Wall and Apron. Routine operation and maintenance including mowing, inspection, and tree removals.