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4.14.6 RILL AND GULLY PLAN <br />The purpose of this plan is to prevent, to the greatest degree feasible, the formation of rills and <br />gullies within the disturbed area, and to provide for repairs if and when gullying occurs. To <br />accomplish this, the rill and gully plan, regrading, backfilling and covering spoil filled areas with non- <br />toxic material, provides for gentle sloes and the re-establishment of natural drainages. <br />To insure that rill and gully formation does not become a serious problem, EFMC will conduct <br />monthly inspections of the disturbed area during the summer months. If, despite EFMC's best <br />efforts, inspection indicated that natural processes are creating significant rills and gullies, EFMC will <br />implemen[ appropriate remedial/protective measures. Mitigation efforts will be done with the <br />objective of preventing further damage by either repairing damaged areas or establishing conditions <br />which will facilitate repair through on-going natural processes. <br />Should rills and gullies begin to form, repair will be undertaken to prevent further erosion. Repair <br />of individual gullies may include placement of hay bales, riprap, or silt fence, or combinations of these <br />methods. Where areal erosion problems have resulted in numerous rills and gullies, mitigation <br />measures may include upslope diversion of drainage, supplemental seeding, mulching, selective <br />placement of sediment fences, contour ditches, or combinations of these methods. <br />In an effort to control erosion on the refuse pile, a series of four contour ditches will be <br />constructed across a portion of the slope face. These contour ditches will reduce the slope length and <br />divert flow across the slope face to upper postmining ditch 1. The upper postmining ditch 1 was <br />reevalua[ed for the additional flow. The contour ditches aze designed to safely pass the 100-year, 24- <br />hour s[orm event under the worst case largest contributing area. The contour ditches aze designed as <br />triangular shaped channels 1.2 feet in depth with 2H:1 V sideslopes, 1% channel slopes, and will be <br />spaced no more than 14 feet vertically. The flow velocity in the contour ditches does not exceed 5 feet <br />per second, therefore, erosion protection is not required. <br />RN-04 684 Revised 01/03 <br />