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• 4.8.1.3 Post Mine Drainanes Stabilization <br />Section 4.8.1.3 discusses stabilization of reestablished drainageways on reclaimed range and croplands. <br />A discussion of postmine topography for reestablished drainageways and associated reconstruction crite- <br />ria are in Section 3.5.3. <br />A drainages channel and its tributaries (drainages) are those features which occur on wncave segments <br />of slopes, and result in a relatively unbroken, defined channel(s) which can be traced to another <br />down~radient stream or channel. Any erosional feature which is within fifty feet etther side of a <br />drainageway will be considered part of reestablished drainageways. A rill or guly outside of the corridors <br />is a sideslope feature and will be handled according to methods discussed in Section 3.8.3.6, Rill and <br />Gully Control Plan. The above definition will aid both Trapper and the Division in distinguishing between <br />those features and areas subject to this section and those subject to Section 3.8.3.6. <br />The final stabilization of drainageways will follow along with vegetative establishment within the drainage. <br />Where periodic water flow prevents vegetative establishment, a temporary channel may be constructed <br />and maintained until the postmine channel is sufficiently stabilized. When such a method is anticipated, <br />the Division will be furnished design criteria for the temporary channel prior to construction. <br />Once final regrade is complete topsoil wi{I either be laid up to the edge of the drainages (but not in the <br />• channeQ or the entire drainages will have topsoil replaced. The decision to topsoil or not to topsoil will be <br />based on several criteria. Acceptable erosion control techniques must be feasible such that topsoil in <br />drainageways can be reasonably protected. However, even with protection, runoff everts may occur that <br />null in some loss of topsoil from the drainages. Also, superior establishmem of vegetation must have <br />been demonstrated through the use of topsoil (see Section 3, 1987-91 Annual Reports). If not, topsoil <br />may not be placed in drainageways. Further, 'rf topsoil placement reduces channel stability, then topsoil <br />wttl not be placed in drainageways. Where the Division approves rip rap as a channel lining, topsoil will <br />nal be placed in the drainageways. <br />• <br />4183 <br />P ~-~4 <br />NlA'f 131998. . <br />