2,000-cubic-yard concrete pour set to take place at the Red Rock Hydroelectric Project
Aug 31, 2017
The largest concrete pour to date at the Red Rock Hydroelectric Project construction site is expected to take place during the week of Aug. 21. Missouri River Energy Services is building the project adjacent to the Red Rock Dam on the Des Moines River southwest of Pella, Iowa.
This is the first concrete placement that will outline the footprint of the intake structure on the dam’s upstream side. It will involve 200 truckloads or 2,000 cubic yards of concrete. This single pour is enough concrete to build 167 feet of a single lane of interstate highway. It is estimated that the pour will take a minimum of 20 hours to complete and, for the most part, will be conducted at night. The placement will be approximately 60 feet by 112 feet and between 7 and 10 feet thick.
During this large concrete placement, there will be more truck traffic in the area than usual, especially along Highway T15, but the road will remain open. Travelers should expect delays and lane restrictions as crews work to get the concrete trucks in and out of the site.
On the downstream side, work has been under way since late June to install roof forms, rebar reinforcement, and embeds for the spiral case roof concrete placements. This work involves the installation of massive amounts of rebar. Concrete for the Unit 1 spiral case roof was placed Aug. 17 and similar work on Unit 2 is expected to be completed by late August or early September.
The spiral case, within the powerhouse, is a large snail-shaped water passageway that causes the water to swirl around into the turbines where it creates the necessary forces to turn the turbine. When the plant is operating, water will enter into the spiral case through a penstock, which is essentially a large conduit that carries water from the upstream side through the dam and into the spiral case. The turbine turns the generator, which is where electricity is generated.
In other construction activity, excavation and bracing are complete for the Unit 1 downstream penstock. Installation of penstock steel liners is expected to begin the week of Aug. 21. Crews will wait to install the last 50 feet of downstream penstock (the portion next to the existing concrete dam) until the intake structure and upstream penstocks are complete and watertight.