IIW worked with Jackson County to provide emergency stabilization of an eroding riverbank. The bank had nearly undercut an existing county road.
During the first phase, IIW completed plans to prevent further erosion by replacing 200 linear feet of riprap armor and the associated fill.
IIW engineers placed bendway weirs in the river channel and configured them in such a way to change the direction of the channel flow to sufficiently to prevent further bank erosion and provide additional stabilization. The plan called for the weirs to be placed under the water for about half of the year and constructed with the same riprap materials as the armoring.
This solution addressed the source of the initial problem that caused the emergency. It also used much less material than armoring and achieved the same goal of protecting the foreslope of the roadway.
The area faced major flooding a few years after the project’s completion. The weirs proved effective in maintaining the channel alignment. However, the bank spurs adjacent to the weirs required some additional stabilization downstream. This experience has further refined this innovative design approach.
The riverbank stabilization required a joint construction application submitted to the U.S. Army Corps of Engineers and the Iowa Department of Natural Resources.