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2.0 METHODS <br />SEDIMENTOLOGY DEMONSTRATION <br />In order to satisfy one of the requirements for sediment pond removal (Rule 4.05.6(14), <br />reclaimed areas must be shown to not contribute additional suspended solids above natural <br />conditions to the receiving waters downstream. There are several methods by which to <br />compare sediment generation from a disturbed site and an adjacent undisturbed site. <br />Historically, CDRMS has used a model (SEDCAD+) to evaluate similar or identical <br />watershed sections within the reclaimed area and adjacent undisturbed area. There are <br />limitations to this approach, as there are rarely identical adjacent watersheds. Further, <br />exact knowledge of all of the parameter values for the areas to be compared is often not <br />available. Given the relatively small size of the disturbance at the Carbon Junction Mine, <br />we elected to compare sediment generation from the reclaimed site and the adjacent <br />undisturbed area through the use of the Universal Soil Loss Equation (USDA, 1982). <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/year. The USLE accounts for rill and inter-rill erosion, the types of erosion <br />commonly found on reclaimed areas. <br />The USLE takes the form: <br />A=R*K*LS*C*P <br />where: <br />A = soil loss in tons/acre/year <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 />Carbon Junction Mine site and adjacent area. <br />Oakridge Energy Carbon Junction Mine Page 2 <br />Sediment Pond Sedimentology Demonstration