Controlled flooding causes suspension of upstream work at Red Rock Hydroelectric Project

Missouri River Energy Services (MRES), on May 25, authorized a controlled flooding of the upstream cofferdam and intake structure excavation at the Red Rock Hydroelectric Project (RRHP). MRES is building the project at the existing Red Rock Dam on the Des Moines River near Pella, Iowa.

MRES authorized the controlled flooding in anticipation of the reservoir level reaching the work platform due to recent rainfalls in the Des Moines River watershed.

The U.S. Army Corps of Engineers (USACE), which is responsible for reservoir control and dam operations, has forecasted that reservoir water levels will rise from 748.5 feet on Thursday, May 25, to 751.5 feet by Tuesday, May 30. The RRHP cofferdam and work platform is at an elevation of 750 feet.

Since flooding of the work site seemed imminent, MRES officials proposed a course of action to suspend upstream work until the flood event is over. The upstream cofferdam is designed to be flooded since the work platform elevation is normally below the reservoir’s water level during the months of June and July in an average rainfall year.

An Emergency Task Force, consisting of representatives from MRES, USACE, Ames Construction, and MWH Americas/Stantec, reviewed the proposal and did not oppose the action. Ames Construction, headquartered in Burnsville, Minn., is the general contractor for the project and MWH Americas/Stantec of Chicago, Ill., is the design engineer. 

Work on the intake structure likely will resume in August, but could resume earlier if water levels drop and the long-range weather forecast calls for relatively dry weather.

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For more information about the Red Rock Hydroelectric Project, visit the project website at www.redrockhydroproject.com or contact Joni Livingston at Missouri River Energy Services, phone: 605-261-3637 or email: joni.livingston@mrenergy.com.