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• basin and Rs principal channel, Thus, premine principal channel widths and associated flood plains will <br />be approximated [o the extent practicable, given the limns of available equipment. Hovrever, in no everrt <br />will principal channel widths be less than premine channel widths. Afso, all principal channels will be <br />constructed to prevent short-circuit or capture by an adjacent principal drainage channel fora 1o0-year, <br />24-hour event in large watersheds and a 10-year, 24-hour event for small (less than one square mile <br />drainage area) watersheds. <br />The length of the drainage route may be increased such that the overall gradient is lowered. By <br />approximating the premine drainage area, lateral adjustments of the drainage routes as necessary to <br />maintain an appropriate gradient are not expected to have adverse consequences on geomorphic <br />stability. Further, by lengthening the course of the drainage, [he rate of flow may be reduced, thus <br />promoting drainage stability. <br />The above goals will be achieved as shown on the postmining topography map, (Map M12). Premining <br />and approximate postmining drainage profiles for all principal drainages are shown on Map M-14, <br />Drainage Profiles. Profile locations are shown on Maps M3 and M12. Section 4.8.1.3 discusses <br />stabilization once regrade activities are complete. <br />• Any temporary diversions constructed around a drainage will be eliminated upon completion of the <br />mining operations in the affected area. As can be seen from the postmining topography map, Map M12, <br />the topography of the surface mined land after regrading will be supportive of the postmining land use of <br />stock grazing, some farming, and wildlife habitat. <br />PR-3 <br />3-43a ~ ~ ?FVISION API' :, <br />~ (DaTE ~/ 3 <br />_ _. -- <br />