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1~ <br />.a <br />Predecisional Draft ~ r, "-~cj 12/28/94 <br />Kerr Coal Company - Marr Strip ,' . <br />Establish a revised reclamation plan for the site that would meet the approximate original <br />contour requirements of the Act and the regulations at this site, without creating unacceptable <br />conditions at other reclaimed azeas. <br />The Procedure Used <br />1. Review the pre-mining condition at the site, utilizing all available photos and maps. <br />2. Review the existing guidance as to what constitutes "approximate original contour." <br />3. Utilize sound engineering practice to develop a final plan that meets the requirements <br />of (2), is stable and is achievable. <br />Basic Desigu Factors Resulting from Utilizing the Above Procedure <br />1. The reclaimed area would closely resemble the general surface configuration of the <br />land prior to mining and blend into and complement the drainage pattern of the <br />surrounding terrain. <br />2. Replacing the ridge line and the associated valley feature in the area where it was <br />removed will result in a shift of the ridge line to the southeast and a widening of the <br />valley feature for the following reasons: <br />a. The natural material in the ridge walls stood at a much steeper slope than the <br />same material is able to do in a backfilled situation. Slopes in the natural <br />undisturbed environment show signs of erosion and instability. <br />b. Slope stability consideration for the side slopes resulted in a maximum design <br />slope of 3:1, thus widening the valley ridge boundaries and extending the <br />feature to the southeast. <br />3. The ridge line would be established in reasonable proximity between the points where <br />it was originally intercepted by Pit PTo. 1., given the design constraints in (2) above. <br />4. The hydrological impacts of the ridge replacement were analyzed in establishing this <br />design configuration. The topography will provide for adequate drainage of the site <br />and complement the drainage of the existing terrain. It was determined that peak <br />Flow and runoff would increase by 0.7 percent in the Bush Draw drainage, west of Pit <br />1, and decrease by 3.4 percent in the unnamed tributary drainage to the east of Pit 1 <br />(see hydrologic impacts attachment). <br />5 <br />