FYRA Engineering was contracted to address bank stabilization needs on a segment of the Elkhorn River near 240th Street. During the June 2010 flooding in the Elkhorn River watershed, approximately 325 ft of land was washed away and the river bank migrated east towards 240th Street. The client was interested in providing immediate protection to the local infrastructure, so an interim solution was implemented while the final, long term solution was designed and permitted. The interim solution included a combination of buried rock windrow and rock rip rap placed directly on the bankline. This construction qualified for a 404 Nationwide Permit, which was obtained. FYRA Engineering’s current contract with the Papio-Missouri River Natural Resources District is to perform the final design, permitting and construction observation of the long term solution.
The design of the long term solution includes the excavation of a pilot channel with a more gentle curvature that would develop into a parallel river channel over time with flood flows. The rate of channel development will dependent upon the frequency and severity of flows in the river, eventually conveying a significant portion of the flow away from the existing bankline of concern. This will reduce the stresses incurred during high flows and reduce the risk of damage along the existing bankline. This design will restore a historic channel of the Elkhorn River and provide aquatic habitat improvements for the endangered pallid sturgeon and other native species of fish. Bathymetric Surveying and two-dimensional hydraulic modeling of the river segment will be performed to assess the stability and flow regimes of the preferred alternative and to plan habitat location and orientation. Permitting coordination with the USACE was performed and construction documents were developed, and construction observation services will be performed upon implementation.