Red Rock Hydro
Project Location: Pella, Iowa
Synopsis of work:
The landscape is changing rapidly as Ames crews continue work on both upstream and downstream areas of construction to retrofit an existing dam for hydroelectric power at the Red Rock Hydro project in Pella, Iowa.
With an August 2014 start, crews spent 18 months performing most of the civil and underground work. By 2016, the project's focus had shifted to constructing the powerhouse, located downstream of the Red Rock Dam, and the intake structure, located upstream. The spiral case walls, floor and roof were built, along with concrete draft tubes that preceded installation of the turbine assemblies.
In early 2017, the draft tube liners for the powerhouse were the first large embedded components set for the turbine-generator units. Stacked vertically with other components, this assembly directs water through the turbine to produce electricity. The passages within the powerhouse-the spiral cases-cause the water to swirl around into the turbine runner, creating the necessary forces to turn it.
Working downstream of the dam, crews are completing one of two penstocks-large pipes that carry water from the upstream intake structure through the dam and into the spiral case. When operating, water will enter the spiral case through a penstock, the turbine turns the generator and electricity is generated.
Throughout the year, crews completed the center and most important parts of the powerhouse, which required stacking multiple embedded parts and constructing the concrete portions of the supporting generator embedment anchors. By year-end crews had begun to install other mechanical support systems within the completed portions of the powerhouse along with the beginnings of the complicated electrical cable tray system that will carry, literally, miles of wires within the powerhouse.
By the end of 2017, the specialized concrete of the new intake structure was taking shape and beginning to reveal itself near the top of the cofferdam. Crews from both our Western and Midwest Regions continue to work together to build a 96-foot-tall structure of unique, thick concrete lifts, as we near completion of all concrete placements for both the powerhouse and intake structure.