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Mr. Thomas Ehmett 5 June 30, 1994 <br />Geomorphic and Erosional Stability - <br />The approved final "Pit 1" topography has been designed to provide a configuration which is <br />both erosionally and geomorphically stable. Properly managed slopes which have gradients no <br />steeper than 3H: l V are frequently reclaimed with a high success rate. The approved concave <br />or incised land feature at "Pit 1" is also a more geomorphically stable feature than a ridge <br />constructed of fill material. Even if complete bacldilling were found to'be possible at "Pit 1," <br />such baclddling would create a fatal configuration which would be less stable, from a <br />geomorphic perspective, than the currently approved topographic configuration. <br />Drainage - <br />The approved postmining configuration for the "Pit 1" area allows positive drainage to the north <br />northwest, and the general drainage configuration does not vary significantly from the premising <br />configuration. The approved configuration both blends into, and compliments the surrounding <br />terrain and drainage pattern. Pn~ipitation-derived nrnoff flowing or falling onto We reclaimed <br />area is accommodated and planned for in an unobstructed and controlled manner. <br />Specifically, all of the premising topography drained to ephemeral drainage basins which are <br />tributary to We Canadian River. The entire reclaimed area still drains to the Canadian River. <br />The Canadian River drainage basin has a total area which consists of nearly 200 square miles, <br />with the "Pit 1" area comprising an insignificant percentage of the total area (a fraction of 1 °b). <br />Each of the tributary ephemeral drainages, located to either side of the "Pit 1" area, consist of <br />several hundred acres. Approximately 15 acres of the premising topography which previously <br />drained to the unnamed ephemeral draw east of the "Pit 1" area, now drains to the much larger <br />ephemeral drainage (Bush Draw) to the northwest. The unnamed draw lies within a drainage <br />basin of approximately 700 acres, of which the approximate 15 acres constitute a mere 2°G. <br />These same 15 acres also constitute an area less than 1 % of the total drainage of Bush Draw. <br />This minor change in the overall local drainage pattern is insignificant, and does not create any <br />negative hydrologic impact. This aspect of the approved plan is in compliance with both the <br />pertinent State and Federal regulations, and it is consistent with the interpretations provided <br />within 1NE-26. <br />Highwalls/Spoil Piles/Depressions - <br />All highwalls, spoil piles and depressions must be eliminated, and they have been eliminated. <br />The approved plan properly accommodates this requirement. <br />