Red Rock Dam, a U.S. Army Corps of Engineers facility on the Des Moines River near Pella, Iowa, got a new powerhouse courtesy of Stantec’s design and a new generation license from the Federal Energy Regulatory Commission. Contractor Ames Construction had to deal with a confined work area, large reservoir level and spillway release fluctuations, unbalanced soil loading from the dam’s slopes and the requirement that all work be carried out with no impact to water control operations. Stantec used vertical Kaplan-style turbine generators to maximize annual power generation and specified an intake structure 99 ft high by 112 ft wide by 60 ft deep with two water passages, two emergency wheel gates and bulkhead slots and storage. The powerhouse measures 150 ft wide by 98 ft deep by 144 ft high. The design also includes a 69-ft-high cantilevered retaining wall that uses 130-ft-tall T-shaped concrete diaphragm walls socketed into rock.