This project is working to establish guidelines for placing coarse bands in streambed simulation culverts to maintain the form of the stream channel and enhance fish passage. At road crossings, restoring fish passage is recognized as a key priority. Stream simulation is one of the design methods that are allowed, and one kind of stream simulation utilizes coarse bands, which are relatively thin regions of sediment that are coarser than the natural streambed material and are placed horizontal to the flow to enhance stream channel stability. They are intended to simulate the natural stream in terms of both bed material and geometry. Of the 3,175 fish passage structures that WSDOT owns, the Washington Department of Fish and Wildlife has determined that 60 percent are barriers to fish passage. More than 800 of these structures must be fixed by 2030, and many will be replaced with stream simulation culverts. Results of this project will include recommendations for the layout, dimensions, and composition of the coarse bands to maximize longevity of the simulated streambed. A key component of this project will also be a standardized procedure for quantifying the performance of a simulated streambed.
Principal Investigator: Nicholas Engdahl, Civil and Environmental Engineering, WSU
Sponsor: WSDOT
WSDOT Technical Monitor: Julie Heilman
WSDOT Project Manager: Jon Peterson
Scheduled completion: December 2020