How is soil bioengineering used to stabilize a streambank or shoreline?
Ms. Sotir: Soil bioengineering is one component in an overall approach. Its application is always based on sound engineering practice, first and foremost. Soil bioengineering includes methods that simply support and stabilize the top few inches of the soil surface as well as those that reinforce to a depth of 10 or 15 feet with the use of synthetic geo-grid or geo-composite materials. In some cases soil bioengineering offers a complete alternative to a “hard” method such as a retaining wall or riprap, but in many cases it is a very useful adjunct to a conventional method. In former times, unless crib systems were used, the natural angle of repose was a limitation for a bioengineered system. In many situations, especially urban areas, space does not allow for that. Now, using vegetated reinforced soil slopes, or VRSS, we can build and establish vegetation to a slope angle of 4V:1H or perhaps 6V:1H, which is a 70% grade. Cost-wise, it is competitive with wall systems in part because you
