Bank Stabilization Using Environmentally Neutral Techniques

Seattle, Washington

HWA provided slope stabilization services at a residential site in the Blue Ridge area of Northwestern Seattle.

The residence exists at the top of an 80-foot, 40 to 70-degree sloped bluff overlooking Puget Sound. This bluff was susceptible to erosion; and HWA was employed to help devise a way to control this natural sloughing. The challenged posed was that "development", such as walls or soil nails, was not permitted. To solve this problem, a root reinforced steel mesh curtain was devised. The curtain was "hung" from cables and a deadman back from the slope. As roots grow they will intertwine with the mesh; thereby transferring load from the soil to the curtain. The result is that weathered soil, which is kept on the slope by the curtain, is not allowed to slough. Additionally, the layer of soil kept on the surface of the bank will slow the rate of weathering of the lower soils.

HWA received a Silver Award at the American Council of Engineering Companies (ACEC) of Washington's 2008 Engineering Excellence Awards for Future Value to the Engineering Profession & Perception by the Public.