Intermittent road restrictions continue as hydro project progresses

Published March 18, 2015

The mild weather this week has allowed crews at the Red Rock Dam to continue working day and night to prepare the site for construction of a powerhouse and intake structure that will comprise the Red Rock Hydroelectric Project (RRHP). Short-term road closures, directed by the Marion County Sheriff’s Department, will occur in the overnight hours every three to four days as crews move large rebar cages from the North Tailwater staging area to the construction area on the upstream side of the Dam. In addition, Highway T-15 will be restricted to one lane every three to four days to facilitate staging of the concrete trucks to ensure worker and public safety as the wall element sections are poured. A pilot car and flaggers will be directing traffic whenever there is a lane closure. Ten elements of the 240-foot diaphragm wall have been completed, with 16 elements still to be placed. 

Ames Construction, headquartered in Burnsville, Minn., finished placing the steel sheeting to form Cell #4 of the cofferdam that will help to keep water out of the site during the construction of the powerhouse on the downstream side of the Red Rock Dam. Crews will install the concrete base and fill the cell with sand during the coming week. Next week, they will also begin to install sheeting for a 335-foot “closure dike” that will connect to the cofferdam to the land. Rock will eventually be placed on each side of the closure dike, making it look like another small dam. Both the cofferdam and the closure dike are temporary structures that will be removed when construction of the project is completed.

Also on the downstream side of the Dam, Ames has dug out the first four feet of the powerhouse excavation and has begun installation of the support structure for the secant pile retaining wall. The support structure will consist of a combination of walers (I-beam braces) and 153 tie-back anchors which will be installed as the excavation proceeds. The tie-back anchors will be drilled into bedrock to ensure the stability of the retaining wall. 

Finally, the first large components of the turbine generators have begun to arrive on-site. Voith Hydro of Heidenheim/Brenz, Germany is the supplier of the turbines and major powerhouse equipment. 

Missouri River Energy Services (MRES) is the builder of RRHP and will be the plant’s operator when the project is complete.  MRES is a joint action agency serving 61 member municipally owned utilities in Minnesota, Iowa, North and South Dakota. Western Minnesota Municipal Power Agency (WMMPA) has provided financing for and is the owner of the project. RRHP is expected to be completed in 2018, at which point it will be the second-largest hydropower facility in Iowa. 

For more information about the Red Rock Hydroelectric Project, visit the project website at

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For more information, contact Joni Livingston at Missouri River Energy Services, phone: 605-338-4042;

Release no. 15-020