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USING THE UNIVERSAL SOIL LOSS EQUATION <br />A= RKLSCP <br />A is the soil loss in Tons/Acre/Year <br />Grease- <br />wood <br />Adjacent <br />NorthPortal <br />GW <br />Reclaimed <br />Shad- <br />scale <br />Adjacent <br />NorthPortal <br />Shad <br />Reclaimed <br />R = rainfall factor <br />P <br />20.00 <br />20.00 <br />20.00 <br />20.00 <br />K = soil erodibili factor - Torriorthents <br />0.37 <br />0.37 <br />0.37 <br />0.37 <br />LS = combined length slope factor <br />North Portal Greasewood - Reclaimed <br />2.754 <br />1.106 <br />21.943 <br />1.346 <br />C = cropping management factor. <br />1.106 <br />0.0466 <br />1.0 <br />0.38 <br />Shadscale Reference Area - Adjacent <br />20 1 0.37 1 <br />21.943 <br />"C"- Crop Management- Greasewood <br />1.0--T <br />13.93 <br />North Portal Shadscale - Reclaimed <br />Canopy <br />11.3% <br />20 1 0.37 <br />1.346 <br />0.0838 <br />1.0 <br />0.83 <br />Cover - Grass <br />4.9% <br />Ground Cover <br />50.1% <br />0.0709 <br />"C" - Crop Management - Shadscale <br />Canopy <br />2.7% <br />Cover - Grass <br />4.1% <br />Ground Cover <br />44.9% <br />0.0858 <br />"C"- Crop Management - North Portal GW <br />Canopy 1 <br />1 22.5% <br />Cover - Grass <br />0.6% <br />Ground Cover <br />58.4% <br />0.0466 <br />"C" - Crop Management - North Portal Shad <br />Canopy <br />8.6% <br />Cover - Grass <br />0.4% <br />Ground Cover <br />45.6% <br />0.0838 <br />P = erosion control practice factor <br />1.00 <br />1.00 <br />1.00 <br />1.00 <br />SOIL LOSS CALCULATION <br />AREA R K I <br />LS <br />C <br />P <br />A <br />Greasewood Reference Area - Adjacent <br />20 0.37 <br />2.754 1 <br />0.0709 1 <br />1.0 <br />1 1.44 <br />North Portal Greasewood - Reclaimed <br />20 1 0.37 1 <br />1.106 <br />0.0466 <br />1.0 <br />0.38 <br />Shadscale Reference Area - Adjacent <br />20 1 0.37 1 <br />21.943 <br />0.0858 <br />1.0--T <br />13.93 <br />North Portal Shadscale - Reclaimed <br />20 1 0.37 <br />1.346 <br />0.0838 <br />1.0 <br />0.83 <br />It can be seen from the above calculation that the revegetated area of the North Portal Greasewood and Shadscale Areas <br />may lose 0.38 and 0.83 tons per acre per year respectively to erosion. The Greasewood and Shadscale Reference Areas, <br />which represents the baseline conditions, may lose about 1.44 and 13.93 tons per acre per year respectively to erosion. <br />The above calculation demonstrates that untreated drainage from the reclaimed areas contributes fewer <br />suspended solids to streamflow or runoff outside the permit area than untreated drainage from the natural <br />surrounding premining area. Pond 13 receives drainage from the North Portal Area. Based on this <br />demonstration, Pond 13 and other drainage control features can be reclaimed. <br />Pond 13 has never discharged, therefore, no quality analysis has been performed on the runoff to or from <br />this pond. The disturbed area will not contribute additional suspended solids above natural conditions, and the <br />quality of untreated drainage from the disturbed area will meet the State and Federal water quality standard requirements <br />applicable after the sedimentation pond and treatment facilities are removed because the surrounding areas are very <br />well vegetated and there is virtually no erosion or other stability issues. It is unlikely any significant runoff from the well <br />vegetated reclaimed area will reach the Colorado River. The calculated runoff from the reclaimed area for the 10 year <br />stone (1.4 ") event for Pond 13 is 0.80 AF (Appendix 14-6), which is insignificant when compared to the average annual <br />runoff generated from the entire Colorado River drainage (2.8 million AF per year). <br />PR -5 A14 -13 -14 02/12 <br />