Protecting the Most Vulnerable and Critical Part of WRA’s System

Located on the banks of the Des Moines River, the Des Moines Metropolitan Wastewater Reclamation Authority’s Wastewater Reclamation Facility is an instrumental treatment facility. Historic river flooding challenged facility operations, which subsequently impacted citizens, businesses, the economy and water quality, and could have been devastating to downstream communities.

After completing an alternatives study with a risk-based decision-making process, the team prioritized resiliency measures that fit the program’s funding. The team utilized a variety of recent assessments, reports, studies and plans; and then performed further site-specific risk-informed flood scenario modeling to determine prevailing flood risks. Improvements include protecting critical facilities at the WRF from flooding resulting from a catastrophic failure of the Des Moines I or Southeast Des Moines levee systems due to a flood overtopping event or a levee breach.

The flood resiliency improvements include a gated floodwall system for the WRF’s preliminary treatment pump headworks facility designed to applicable U.S. Army Corps of Engineers floodwall design standards. Other improvements include replacing and elevating the electrical transformers that service the pumps, constructing a new elevated building facility for the updated switchgear that controls the WRF’s electrical power, and co-locating standby power generation in the new building in the event incoming commercial electrical service is lost during a catastrophic flood event.

The Des Moines WRF Flood Resiliency Study focused on internal flooding, critical plant infrastructure and riverine flooding to identify, quantify and evaluate the risk of inundation for a variety of sources. Projects that had merit in reducing flood damage were then designed and constructed to improve the flood resiliency of the WRF and the sustainability of services.