Bioengineered Method for Repairing Road Shoulders Associated with Stream Banks

In the Puget Sound region, streams are commonly found associated with road prisms. The impacts of road shoulders/prisms on stream habitats where they meet includes the lack of complicated habitat and cover which has been shown to be essential to fish (especially listed fish species) as well as other aquatic resources. Road shoulders are commonly constructed with rock, fill or other hard armoring which has been suggested to have negative influences on stream/habitat quality (chemical, habitat forming and hydrological processes). Typically road prisms wash outs are repaired by placing rock (Rip Rap) or other hard structures.  Natural resource agencies often require removal of these types of repairs, or require expensive mitigation to mitigate for loss of potential/existing habitat.  Construction methods of more fish-friendly repairs which are not only effective in protecting infra structure but, also provide for stream processes which form habitat are worth considering. One of these methods of structural earth walls and reinforced slopes which are constructed using engineered coir-topsoil faced geogrid wraps with the placement of large woody debris (LWD) and plantings , may be an alternative efficient and effective method to provide for the protection of fish and road structure as well as improving permitting needs.