Des Moines seeks savings in swollen levee budget
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Flooding in 1993 damaged large sections of downtown Des Moines. Photo: Brooks Kraft LLC/Sygma via Getty Images
A series of Des Moines levee improvements are almost $35 million over budget, prompting the City Council on Monday to adopt a new evaluation plan to try to reduce costs.
Why it matters: The improvements were designed after floods in 1993 and 2008 caused billions of dollars in damages.
- While the potential for savings is appreciated, there's concern about whether the levee systems can safeguard against future disasters, Mayor Frank Cownie said during a council workshop Monday.
The other side: The semi-quantitative risk analysis (SQRA) evaluation may provide a better understanding of flood risks at specific points in DSM's levee system, Patrick Beane, the city's clean water program administrator, told council members.
- Operations and maintenance could provide better protection and reduce the need to build some levees as high, Beane said.
Catch up fast: More than 15 miles of levee systems surround DSM. Many were built between 1963 and 1972, with segments that were unable to withstand the flooding of recent decades.
- The Army Corps in 2010 updated flood frequency estimates, which resulted in a $65 million, eight-phase plan that focuses largely on raising DSM levee heights.
State of play: Construction started in 2019. One phase is completed, one is almost done and another started this spring.
- The other phases are all downstream of Southeast 14th Street on the DSM River and are in design phases.
What's happening: The price tag has increased since the 2019 estimates because of a rise in labor and material costs after the pandemic as well as previously unidentified factors that require additional work, Beane said.
- Under Monday's agreement, the city will spend just over $572,000 to conduct the SQRA with the Army Corps.
- The savings could exceed $9 million, Beane told the council.
Of note: Kansas City recently used an SQRA and mitigated potentially $250 million in costs and scheduled risks, according to the Army Corps.
What's next: DSM's evaluation will take 12 to 18 months.
- Completion of some of the phases may be extended beyond 2028 as a result, Beane said.