Erosion Control Techniques
The primary purpose of erosion control is to reduce the erosive effects of surface water runoff on exposed soil. As a reminder, reducing the source of the surface water runoff can provide a significant improvement to erosion problems and should be the first step taken.
How erodible exposed soil is to surface water runoff depends on several factors such as type of soil, steepness of the slope, and height of slope. Erosion control techniques tend to focus on ways to reduce the magnitude of these factors.
Some techniques are more appropriate during temporary earthwork activities during construction rather than more permanent site conditions. For example, exposed cut and fill slopes during construction are commonly covered with plastic sheeting (visqueen) to limit the erosion of these soils. The plastic sheeting is replaced with vegetation for a more long term solution. Plastic sheeting has found its way to residential properties with its use commonly extended to longer time frames. Plastic sheeting should be considered a temporary solution rather than a permanent one.
There are many techniques available for erosion control. During construction, they include mulching, matting, covering with plastic sheeting, silt fences, settling ponds and protective berms. Your local public works department can provide more information on best management practices for erosion control. More permanent controls include installation of vegetation or other slope protection materials and slope recontouring. Vegetation can be established through seeding, container or bare root planting. Vegetation used in contour wattling and brush layering can also reduce slope lengths, thereby reducing the erosion potential on the slope. The Ecology manual Slope Stabilization and Erosion Control should be referenced for more information on vegetative techniques.
There are also a number of erosion control blankets available that can be used to protect the exposed slope while the vegetation is getting established. These blankets range from mats of non-biodegradable materials to biodegradable jute netting.
For areas where vegetation cannot be established, e.g. steep slopes or high volume of runoff, hard surfacing such as large, angular rock (4 to 6-inch diameter) can be used to protect underlying erodible soil. Placement of a geotextile between the underlying soil and the rock surfacing would reduce the amount of soil that would move through the voids in the rock surfacing.
Slope recontouring (terracing or flattening) involves modifying the slope configuration on a large scale to improve slope stability. This should only be done with the guidance of a geotechnical engineer. Without proper review of the slope conditions, slope recontouring could make slope stability conditions worse.
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