FLOOD03925 - Laserfiche WebLink

Home Browse Search

2. Stream Channel Protection (Non- Vegetative Techniques) The Bonded Fiber Matrix (BFM) selected by the U.S. Forest Service for application at Buffalo Creek is unique in its high level of erosion control effectiveness, application procedures and cost. For these reasons and others, it is important that it be used on the most critical areas in the watershed and not where other cost-effective practices would be more appropriate. Typically, the BFM is specified under the following conditions: . Highly erodible soils or areas of loose ash; . Steep gradients of 3: I or greater; . Areas devoid of vegetation which required temporary surface treatments to stay in place until vegetation is established; . Areas where erosion and downslope delivery of sediment would impact significant resources, including public safety, transportation corridors, homes, businesses and infrastructure; . Slopes where steepness or instability presents unsafe working condition for ground labor; and . Areas which require immediate and rapid deployment of effective erosion control. Clearly, the area previously selected by the V,S Forest Service meets most, if not all, of these criteria. The slopes on the east side of the County Road 126 are of highly erosive, decomposed granite and are without vegetative cover to prevent dislodgment and transport by rainfall. Movement of sediment from these areas during significant rainfall events has already been documented during the July 12th storm. Many of the culverts beneath the road are currently plugged with sediment, exacerbating the flood hazard conditions along the road bed. Application of the BFM and subsequent vegetation establishment will reduce the potential for erosion and sediment delivery downslope from these areas. Similarly, slopes on the west side of the road and adjacent to the creek have the potential to contribute to significant sediment loads to the creek itself. These sediment loads create adverse impacts by bulking the flow above normal levels, imperiling downstream properties in Buffalo Creek, and impacting the water supply system already damaged by the summer storm events. Application of the BFM and eventual revegetation of these slopes, coupled with contour tree felling and rotoclearing in the upper watersheds, will reduce this area's contribution to the overall amount of sediment going into the creek. There were several mitigation measures implemented and installed after the Southern California Fires of 1993. These measures were included in a document entitled Post-Fire Hazard Mitigation 33