Laserfiche WebLink
<br />Methods For Controlling Erosion <br /> <br />e <br /> <br />FIGURE 4. 7 <br /> <br />Gabion <br /> <br />Existing <br />Banldine <br /> <br /> <br />N.W.S. <br /> <br />Varies <br /> <br />J <br /> <br />- Slone Toe <br /> <br />Geotextill:S - On small streams a good vegetative cover of grass or shrubs may be <br />sufficient to protect streambanks from scour. But if the soils consist of easily erodible <br />material s IICh as sand or gravel, it is often necessary to provide temporary cover until the <br />vegetation has become established. Various natural and synthetic fibers have been <br />developer I for use in erosion prevention. Many different applications may employ <br />specific flobrics that are available. A list of manufactures is presented in Appendix A. In <br />most cas<~s involving /lowing water, fabrics used alone do not provide sufficient <br />protectior, due to their buoyancy and their tendency to be moved by currents. Fabric <br />used in conjunction with vegetation is often an effective solution. Fabrics are also used <br />frequentI]' as a bedding for revetments to prevent leaching of fine bank materials. <br />Geotextil.:s used with vegetation produce the same environmental benefits as vegetation <br />used alon:. The major benefit is aesthetic, but when woody vegetation is used, riparian <br />benefits (an be significant, and there may be some aquatic benefits from shade and <br />organic d,:bris falling into the stream. The benefit of using fabrics with riprap is entirely <br />structural. Figure 4-8 shows a typical layout when using geotextiles. <br /> <br />Fabrics h:lve been used on streams in many locations. In areas without sufficient rainfall <br />to support dense plant cover. supplemental irrigation is usually required if vegetation is <br />used. <br /> <br />Geotextil:s wOIk well in providing temporary protection until vegetation can become <br />establish,d al sites where they are nol exposed 10 swifl currents for prolonged periods of <br />time. Natural geotextiles lend to function better than synthetics due to their ability to <br />breakdo\\ n, to absorb moisture. and to create favorable growing environments. Costs <br />vary con:liderably with vegetation type, placement requirements, and so on. 1YPical <br />uses on a 100fool high bank may range from $15 10 $60 per linear fool. <br /> <br />Soil Cement - Primarily used on the upper bank, soil cement fonns a protective layer <br />over the 1l3Dk. Mixed with 15% portland concrete, bank soil is compacted 10 provide a a <br />stable swface. To prevenl structural damage, hydrostatic pressure should be reduced by .. <br /> <br />34 <br /> <br />Colorado Erosion Control Manual <br />