Ravine Stabilization, Grade, Slope, and Streambank Stabilization on Small Streams in Northeast Illinois

摘要

This presentation will focus on stabilization efforts on two wooded ravine streams, and one small stream in Northeast Illinois. Each ravine used two separate approaches for long term stabilization and restoration of eroded areas. The first ravine stabilization site involved severe channel erosion and incising of an intermittent stream. Initial stabilization efforts to address additional stormwater discharge to the ravine had resulted in failure and continued erosion of the ravine bottom. The project involved the installation of grade control structures, stone toe stabilization and seeding to restore channel stability.The second ravine stabilization involved a steep slope on a wooded ravine adjacent to a new commercial development. A perennial stream at the bottom of the 50 foot deep ravine along with a portion of the ravine slope was impacted for installation of a water main. Initial stabilization efforts using straw erosion matting had failed in efforts to stabilize the slope. In addition, a side hill seep had led to saturation of the slope and concern for the structural stability of the slope. Selection of an appropriate native seed mix, erosion control blanket / turf reinforcement matting, and installation of coir fiber logs at the normal water line of the perennial stream led to successful stabilization of the ravine slope.Small stream bank and bed stabilization will also be demonstrated through the use of re-directive and energy dissipation devices such as stream barbs, bendway weirs, and rock riffles. These techniques in incised stream channels, found throughout the mix of urbanizing and agricultural areas of northeast Illinois, are especially effective in helping curb excessive bank and streambed erosion. The design and installation of these practices will be examined using the overall framework of the channel evolution model and general principles of fluvial geomorphology.