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N UNITED STATES DEPARTMENT OF AGRICULTURE Soil Conservation Service Colorado Technical Guide Section IV All Field Offices July 1981 STANDARDS AND SPECIFICATIONS CRITICAL AREA PLANTING (ac.) (342) Standard Planning considerations DPfi ni tinn Planting vegetation, such as trees, shrubs, vines, grasses or forbs, on highly erodible or critically eroding areas (does no[ include tree planting mainly for wood products). Purpose To stabilize the soil, reduce damage from sediment and runoff to downstream areas, and improve wildlife habitat and visual resources. Conditions where practice applies On highly erodible or critically ero- dible or critically eroding areas. These areas usually cannot be stabil- ized by ordinary conservation treat- ment and management and, if left untreated, can cause severe erosion or sediment damage. Examples of applicable areas are dams, dikes, mine spoil, levees, roadsides, cuts, fills, surface-mined areas, and de- nuded or gullied areas where vegeta- tion is difficult to establish by usual planting methods. Critical area planting should be applied only on sites that have the capability of supporting vegetation. Some critical areas are so hostile [o plant growth, because of climate, soils or slope, that stabilization can be achieved only through struc- tural measures. Other conservation practices, including but not limited to diversions, land smoothing, obstruction removal, surface and subsurface drains, and underground outlets, may be necessary to prepare a critical area for planting. Site pre- paration accomplished through the appli- cation of the above practices should result in a site meeting the following, standards. 1. Land slopes should not exceed 50 percent (2:1) and should be flatter where feasible and practicable. 2. Soils or soil materials must have sufficient depth and potential fertility to support the type of ~vege[ation to be established. 3. Materials such as rocks and trash that will interfere with planting must be removed. 4. Runoff water from the site or adja- cent areas must be controlled in a manner that will prevent serious erosion and damage to the planting. Specifications Topsoiling In the event that the soils have insuffi- cient depth or have physical character- istics unsuitable for development of vegetative cover, topsoil or soil material having the capability of supporting the planned vegetative planting shall be brought in and spread over the deficient areas. The material must be applied uniformly in sufficient depth to support the type and quality of vegetative cover planned for the site. Source of materials must be approved by [he responsible technician. TGN II170