2008-11-18_REVISION - C1981008 (2)

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Summary of "C" Factors Pre-Mine Dryland Pasture 0.006 Post-Mine Dryland Pasture 0.059 Pre-Mine Irrigated Pasture 0.0258 Post-Mine Irrigated Pasture 0.0251 "C" Factors for Permenant-Pasture and Rangeland (EPA, 1977) Vegetative Canopy Cover That Contacts the Surface 1/. Type and Height Canopy Percent Ground Cover of Raised Canopy 2/ Cover 3/ Type 4/ 0 10 20 40 .60 80 95-100 No appreciable canopy G 1.0 .45 .20 .10 ..042 .013 .003 W 1.0 .45 .24 J5 .090 .043 .011 Canopy of tall forbs .25 G 1.0 :36 . 17 .09 .038 .012 .003 or short brush W 1.0 .36 .20 .13 .082 .041 .011 (0.5 in fall ht.) 50 G 1.0 .26 .13 .07 .035 .012 .003 W 1.0. .26 .16 . .11 .075 .039 .011 75 G 1.0 .17 .10 .06 .031 .011 .003 W 1.0 .17 .12 .07 .067 .038 .011 Appreciable brush 25. G 1.0 .40 .18 ' :09 .040 .013 .003 or brushes W 1.0 .40 .22 .14 .085 .042 .011 (2 in fall ht.) 50 G I.0 .34 .16 .085 • .038 .012 .003 W 1.0 .34 .19 .13 .081 .041 .011 75 G .1.0 .28 .14 .08 .036 .012 .003 W .1.0 .28 .17 .12 .077 .040 .011 Trees but no appreciable 25 G 1.0 .42 .19 .10 . .041 ..013 .003 low brush W 1.0 .42 .23 ? .14 .087 .042 .011 ,,(4 in fall ht.).50 G. 1.0 .39 .18 .09 .040 .013 .003 W 1.0 .39 .21. .14 .085 .042 .011 - 75 G 1.0 .36 .17 .09 .039 .012 .003 . I/ All values shown assume: (1) random distribution of mulch or vegetation, and (2) mulch of appreciable depth where it exists. 2/'Average fall height of waterdrops from canopy to soil. surface:' m=meters. 3/ Portion of total-area surface that would be hidden from view by canopy in a vertical projection, (a bird's-eye view). .4/ G: Cover at- surface is grass, grasslike plants,. decaying compacted duff, or litter.. W: Cover at surface is mostly broadleaf herbaceous plants as weeds with little lateral-root network near the surface, and/or !undecayed residue.) Table 3 - "C" Factors for Universal Soil Loss Equation 24