Since the ground breaking ceremony for the Red Rock Hydroelectric Project at Rock Island District's Lake Red Rock Dam near Pella, Iowa, on Aug. 13, 2014, many things have changed. Areas both above and below the dam have visible signs of progress and although the completion date of April 2018 is still more than two years away, Missouri River Energy Services (MRES) says they are pleased with the work being done and feel the project is moving forward as scheduled.
On the downstream side of the dam the project's general contractor, Ames Construction, has completed installation of a secant pile wall designed to hold back the existing portion of the earthen dam. This wall, made out of reinforced concrete secant piles with nine rows of horizontal steel I-beams, tension anchored into bedrock has been important for keeping the dam stable during preparations for powerhouse construction. Removal of the bedrock below the dam was necessary to create the depth and expose a solid base for the new construction. Explosive blasting was used to loosen the bedrock for removal. Blasting began in early November and was completed in mid-December.
District Hydropower Coordinator, Jim Bartek, who manages the Non-federal Hydropower Program which includes the Red Rock Hydroelectric Project, says the blasting is needed to excavate bedrock about 30 feet in depth. The resulting excavation will allow the new hydroelectric powerhouse foundation to be set deeper than the foundation of the dam.
Each time an explosive is used, the highway which runs on top of the dam is temporarily closed and sirens are sounded to inform the surrounding area of the pending blast. After the blast is verified to be complete, the area is given the "all clear" and traffic is reopened across the dam. Videos of the blasts from early November can be viewed online at www.redrockhydroproject.com.
On the upstream side of the dam changes can also be seen. A support structure, called a diaphragm T-wall, has been built to hold the existing dam in place and provide a channel that will eventually allow water to pass into the intake structure, through the penstocks, and into the turbine and generator. A sheetpile cofferdam for the intake structure has also been installed.
The Red Rock Hydroelectric Project is licensed by the Federal Energy Regulatory Commission. Although the powerhouse will be owned and operated by MRES, the Red Rock Dam and spillway will continue to be operated by the Corps of Engineers. The license requires the release of water from the lake and that the reservoir levels be maintained the same as they were prior to construction of the project.
Once completed, the electricity produced by the facility will flow through a transmission line to a substation located on the west side of Pella. From there the electricity will be distributed to the regional transmission grid. The estimated annual energy produced by the project will be 178,000 megawatt-hours which is enough to power approximately 18,000 homes for a year.
For more information about progress at the Red Rock Hydroelectric Project visit the Missouri River Energy Services website at www.redrockhydroproject.com.
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