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nov 22 O5 08:12a Edith Savage 303 665 6808 <br />2.0 METHODS <br />SEDIMENTOLOGY DEMONSTRATION <br />i <br />In order to satisfy one of the requirements for Phase II bond release, reclaimed areas must <br />be shown to corrtribute equal or less sedimern to the receiving waters downstream. There <br />are several methods by which to compare sediment generation from a disturbed site and <br />that from an adjacent undisturbed site. Historically, CDMG has used a model <br />(SEDCAD+) to evaluate similar or identical watershed sections within the reclaimed area <br />and adjacent undisturbed area. There aze limitations to this approach, as there aze rarely <br />identical adjacent watersheds. Further, exact knowledge of all of the parameter values for <br />the areas to be compared is often not available. Given the relatively small size of the <br />disturbance at the Keenesburg Mine, we elected to compare sediment generation from the <br />reclaimed site and the adjacent undisturbed azea through the use of the Universal Soil Loss <br />Equation (USLE) (Wishmeier and Smith, 1965). <br />The USLE uses readily available information on the rainfall, topography, soil particle size <br />characteristics, vegetation, and cultivation practices to generate the amount of soil loss in <br />tons/acre/yeaz. The USLE accounts for rill and irner-rill erosion, the types of erosion <br />commonly found on rec[ainled areas. <br />The USLE takes the form: <br />A=R*K*LS*C*P <br />where: <br />A = soii loss in tons/acrelyear <br />R =rainfall factor accounting for the interrelationship between the erosive <br />force of rainfall and runoff <br />K =soil erodibility factor addressing a given soil's susceptibility to erosion <br />LS =length slope factor providing the ratio of soil loss at any length and slope <br />to a standard slope and length <br />C =cover factor accounting for plant and litter cover on the ground surface <br />P =control practice factor addressing the erosion reduction effectiveness of soil <br />conservation practices <br />Each of the above factors will be briefly addressed relative to the existing conditions at the <br />Keenesburg Mine site and adjacent azea. <br />p.5 <br />Coors Energy Campary Keeneaburg Mine Paga 2 <br />Phase II Bond Kaleaee 5edimerrtology DemoneSration <br />