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Diaphragm wall completed at Red Rock Hydroelectric Project

Aug 19, 2015

Diaphragm wall completed at Red Rock Hydroelectric Project

Work has been completed on a 240-foot diaphragm wall at the Red Rock Hydroelectric Project near Pella, Iowa.

The diaphragm wall is designed to hold back the existing Red Rock earthen dam on the upstream side of the dam and provide a channel for water to enter an intake structure that will send water to the hydroelectric turbine/generator.

Ames Construction, the general contractor for the project, also has completed installation of the secant pile support structure on the downstream side of the project. The secant pile wall consists of nine rows of walers (horizontal steel I-beams) and 153 tie-back anchors that were drilled into bedrock. This structure is designed to hold back the existing downstream earthen dam and to ensure stability of the dam during excavation for the powerhouse. The bottom of the excavation is currently at 25 feet below river level.  In the upcoming weeks, the excavation procedure will include underground blasting to break up rock for removal. Missouri River Energy Services (MRES) will issue a news release prior to the commencement of blasting.

In all, it is estimated that about 28 percent of construction work for the project has been done. When the project is completed in the spring of 2018, it will provide 36.4 megawatts of clean, renewable hydroelectricity, enough to power about 18,000 homes.

At its Aug. 13 meeting, the Western Minnesota Municipal Power Agency, which is providing financing for, and is the owner of the Red Rock project, approved a transmission construction contract with Aevenia of Moorhead, Minn.

The contract calls for Aevenia to build about five miles of 69-kilovolt single-pole transmission line between the Red Rock Hydro substation and the Pella West substation. It is anticipated that this transmission project will be completed in October 2016.