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

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USING THE UNIVERSAL SOIL LOSS EQUATION A= RKLSCP A is the soil loss in Tons/AcreNear Grease- wood Adjacent Cameo TS Piles Reclaimed Shadscale Reference Adjacent CRDA #2 Reclaimed R = rainfall factor A 20.00 20.00 20.00 20.00 K = soil erodibili factor - Torriorthents 0.0709 0.37 0.37 0.37 0.37 LS = combined length slope factor 2.35 0.38 18.56 6.641 C = cropping management factor. 20 1 0.37 1 18.56 0.0858 1.0 11.78 Cameo Refuse Disposal Area #2 - Reclaimed "C"- Crop Management- Greasewood 0.0586 1.0 2.88 Canopy 11.3% Cover - Grass 4.9% Ground Cover 50.1% 0.071 "C" -Crop Management - Shadscale Canopy 2.7% Cover - Grass 1 4.1 Ground Cover 1 44.9%1 0.08579 "C" - Crop Management - Cameo Tops il Piles Canopy 22.3% Cover - Grass 0.0% Ground Cover 49.5% 0.072 "C" - Crop Management - CRDA #2 Canopy 18.1% Cover - Grass 1.0% Ground Cover 54.3% 0.05862 [P-= erosion control practice factor 1.00 1 1.00 1.00 1.00 SOIL LOSS CALCULATION AREA I R K I LS I C P A Greasewood Reference Area - Adjacent 20 0.37 1 2.354 0.0709 1.0 1.23 Cameo Topsoil Piles - Reclaimed 20 0.37 0.379 0.0725 1.0 0.20 Shadscale Reference Area - Adjacent 20 1 0.37 1 18.56 0.0858 1.0 11.78 Cameo Refuse Disposal Area #2 - Reclaimed 20 1 0.37 1 6.641 0.0586 1.0 2.88 It can be seen from the above calculation that the revegetated area of the Cameo Topsoil Piles and Cameo Refuse Disposal Area #2 may lose 0.20 and 2.88 tons per acre per year respectively to erosion. The Greasewood and Shadscale Reference Areas, which represents the baseline conditions, may lose about 1.23 and 11.78 tons per acre per year respectively to erosion. The above calculation demonstrates that untreated drainage from the reclaimed areas contributes fewer suspended solids to streamflow or runoff outside the permit area than untreated drainage from the natural surrounding premining area. Pond 10 receives drainage from the Cameo Topsoil Piles and Cameo Refuse Disposal Area #2. Based on this demonstration, Pond 10 and other drainage control features can be reclaimed. Pond 10 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 10 year storm (1.4 ") event for Pond 10 is 0.61 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 -13-7 02/12