3I4: Physical Model Study of the Proposed Low Froude Number Stilling Basin at Cedar Falls Hydroelectric Project
July 13, 2022
Water and Environment (including Social Issues)
The Cedar Falls Hydro Generating Station is owned and operated by Xcel Energy on the Red Cedar River. The mostly-hollow Ambursen dam was constructed in 1910 and is about 60 feet tall. The project is incapable of passing the current inflow design flood (IDF) prior to overtopping. After an initial study to compare remediation options, the spillway was redesigned with six large tainter gates on an ogee spillway and a smaller crest gate to pass debris and lower return period flows. The uncommon alternative low Froude number stilling basin described by the United States Bureau of Reclamation was chosen to contain the hydraulic jump and dissipate energy for flows through the modified spillway. The St. Anthony Falls Laboratory at the University of Minnesota constructed a 1:36 scale physical model of the entire structure including the proposed spillway replacement and low Froude number stilling basin to validate the stilling basin.