Leavenworth County Fishing Lake Spillway Replacement

The Kansas Department of Wildlife, Parks and Tourism (KDWPT) retained Benesch to design a replacement for the existing spillway at Leavenworth County Fishing Lake. The Leavenworth County State Lake Dam was completed in 1931 for recreational use. The dam is reclassified as size 4, Class “C” High Hazard structure located on a tributary of Ninemile Creek in Leavenworth County, Kansas.

The spillway is located on the west side of the dam and consists of a 130-foot concrete weir that flows into a concrete-lined channel to the base of the dam. While the dam had undergone repairs and modifications over the past 40 years, the concrete chute spillway had experienced significant deterioration over the years and portions of the spillway are near collapse.

Due to these structural issues, Benesch conducted a study to review the hydraulics of the structure as well as make recommendations for repairing the concrete spillway. Based on the condition of the existing spillway, it was decided that further repairs would not be sufficient and that a new spillway would need to be constructed.

The design of the new spillway included multiple features such as the replacement of the spillway with a reduced width, modified cross-section and profile, an energy dissipation system and an early warning system.

Based on an analysis of multiple spillway and energy dissipation systems, the most economical solution was determined to be a flip bucket design with a riprap plunge pool.