2012-07-10_PERMIT FILE - C1981041 (5)

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RECLAIMED AREA - "C" FACTOR Cameo Borrow Area #2 Canopy is assumed to be the combined cover contributed by trees and shrubs. Based on the 2010 Vegetation Evaluation the combined tree and shrub cover totals 27.5%. The percent ground cover for the reclaimed area shown on the preceding page is 56.7 %. Use figure 7 identified above and interpolate to determine the C factor for 56.7% cover and a canopy of tall forbs or short brush. CANOPY TALL FORBS OR SHORT BRUSH PERCENT GROUND COVER 40.0% 56.7% 60.0% 25% G 0.090 0.047 0.038 27.5% dacent "C" Factor 0.046 50% G 0.070 0.041 0.035 USING THE UNIVERSAL SOIL LOSS EQUATION A= RKLSCP A is the soil loss in Tons/Acre/Year Grease - wood Adjacent CBA#2 Reclaimed R = rainfall factor 20.00 A= RKLSCP A is the soil loss in Tons/Acre/Year Grease - wood Adjacent CBA#2 Reclaimed R = rainfall factor 20.00 20.00 K = soil erodibili factor - Torriorthents 0.37 0.37 LS = combined length slope factor 2.41 2.06 C = cropping management factor. "C"- Crop Management- Greasewood Canopy 11.3% Cover - Grass 4.9% Ground Cover 50.1% 0.071 "C" - Crop Management - CBA#2 Canopy 27.5% Cover - Grass 0.8% Ground Cover 56.7% 0.046 P = erosion control practice factor 1.00 1.00 SOIL LOSS CALCULATION AREA R I K I LS C P A Greasewood Reference Area - Adjacent 20 1 0.37 2.41 0.071 1.0 1.26 Cameo Borrow Area #2 - Reclaimed 20 1 0.37 2.06 0.046 1.0 0.70 It can be seen from the above calculation that the revegetated area of the Cameo Borrow Area #2 may lose about 0.70 tons per acre per year. The adjacent area may lose about 1.26 tons per acre per year to erosion. The above calculation demonstrates that untreated drainage from the reclaimed area contributes fewer suspended solids to streamflow or runoff outside the permit area than untreated drainage from the natural surrounding premining area. Pond 11 receives drainage from the Cameo Borrow Area #2. Based on this demonstration, Pond 11 can be reclaimed. Pond 11 has never discharged, therefore, no quality analysis has been performed on the runoff to or from this pond. The disturbed area will not contribute additional suspended solids above natural conditions, and the quality of untreated drainage from the disturbed area will meet the State and Federal water quality standard requirements applicable after the sedimentation pond and treatment facilities are removed because the surrounding areas are very well vegetated and there is virtually no erosion or other stability issues. It is unlikely any significant runoff from the well vegetated reclaimed area will reach the Colorado River. The calculated runoff from the reclaimed area for the 25 year stone (1.8 ") event for Pond 11 is 0.66 AF (Appendix 13-2), which is insignificant when compared to the average annual runoff generated from the entire Colorado River drainage (2.8 million AF per year). PR-5 A14 -13-10 02/12