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<br />2 <br />The reclaimed site has the same general surface configuration of gently rolling and flat <br />terrain as the surrounding range land and hay fields. The only exceptions are the steeper <br />portal face up areas, which were reclaimed to the original contours, and three outslopes of <br />the terrace benches. All surface drainage from the mine site will continue to follow pre- <br />mine drainage patterns by flowing toward the Colorado River to the north, after sediment <br />ponds are removed. There are no highwalls, refuse piles, or spoil piles at the mine site. <br />The Coal Ridge Mine was reclaimed to approximate original contour. <br />In regard to terraces: <br />Rule 4.14.2(2) contains six performance standards for terraces on reclaimed mine sites. <br />Three of these (paragraphs a,b, and c) are relevant to this TDN. The configuration of <br />terraces currently at the site was approved by the Division as part of technical revision 10 <br />to the Coal Ridge permit in 1994. The three relevant performance standards in Rule <br />4.14.2(2) were considered by the Division and addressed by the operator as follows. <br />1. Rule 4.14.2(2)(a) indicates terrace benches shall not exceed twenty feet in <br />width, "unless specifically approved by the Division as necessary for stability, <br />erosion control, or roads included in the post mining land use plan". The <br />Division specifically approved retention of terrace benches wider than twenty <br />feet at Coal Ridge because the post mining agricultural land use of <br />pastureland is enhanced by the addition of level ground. The level ground <br />(the gradient on the benches is l-2%) also helps to minimize erosion from the <br />reclaimed area during the time vegetation is becoming established. <br />2. Rule 4.14.2(2)(b} indicates the vertical distance between terraces shall be as <br />specified by the Division to prevent excessive erosion and provide long-term <br />stability. The Division did not specify a required vertical distance between <br />terrace benches at Coal Ridge because this did not appear to be a significant <br />factor in regard to erosion control or stability. The average gradient change <br />from the upper to the lower terrace is approximately five degrees, and the <br />total vertical relief is approximately thirty seven feet. <br />3. Rule 4.14.2(2)(c) indicates, <br />"The slope of the terrace outslopes shall not be stepper than 2h:ly (50 <br />percent}. Outslopes which are steeper than 2h:ly (50 percent) may be <br />approved, if they have a minimum static safety factor of 1.3, provide <br />adequate control over erosion, and closely resemble the surface <br />configuration of the land prior to mining." <br />