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that of smooth brome closer than the other choices. The shape of the reclaimed channels was <br />• assumed to be trapezoidal with 3H:1V side slopes as a worst case condition. The side slopes will be <br />no steeper than 3H:1 V. <br />The channel bottom width was also calculated using SEDCAD*. Attachment 20-1 shows all input and <br />output information. All reclaimed stream channels will be conservatively constructed to these <br />measurements. Some drainages will also require a riprap lining for channel protection. Please refer <br />to the individual calculations for the proper riprap sizes to be utilized. Table 20-2 is a summary of the <br />postmining channel characteristics. Attachment 20-1 contains design calculations for the postmining <br />channels. <br />After the watershed has been graded and the location of the drainage channel determined, the <br />channel will be constructed to the required shape. At first the channel will be untopsoiled to allow for <br />initial stabilization. During the period when the watershed area is revegetating, the drainages will be <br />inspected for stability according to the rill and gully plan in Tab 22. Maintenance or monitoring that <br />may be necessary as a result of the inspections will be submitted to CMLRD for review and, if <br />necessary, approval. The methods used to stabilize the channels could include installation of <br />approved check dams and livestock ponds, erosion control matting, riprap, and straw dikes. The <br />reclaimed drainage channels will then be topsoiled and revegetated according to Tabs 21 and 22, <br />respectively after the channel has stabilized. The side slopes of the meanders of the reclaimed <br />• drainage channels will be protected from erosion by revegetation with drainage seed mix and shrub <br />plantings according to Tab 22. Maintenance of reclaimed drainage channels will be identified <br />according to the Rill and Gully Plan in Tab 22. <br />Disturbance Area <br />The maximum extent of all areas anticipated to be disturbed by mining, facility, and access <br />construction, and all reclamation activities at Seneca II-W have been identified and are entirely <br />encompassed within the disturbance boundary as depicted on Exhibits 20-1 and 20-1A in this permit <br />application. The extent of this boundary was conservatively defined, and may include areas, <br />particularly in the vicinity of roads and impoundments, that will not be affected by any disturbance. <br />An affected lands boundary map was not generated. The affected lands could be considered the <br />area between the disturbance boundary and the permit boundary. The area within the mining <br />disturbance boundary includes the area mined, the area upon which spoil is deposited and graded, <br />and where final highwalls have been reduced. <br />• <br />11 Revised 9/98 <br />