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

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PR-5 LS (length and percent slope) factors account for the length and percent slope. These factors are taken from Figure 4. Length of slope begins at the top of the micro watershed. This is usually at the top of a hill, ridge, terrace or diversion. The length of slope is considered to end for a given field at one of the following places: (1) the point where the slope decreases to the extent that deposition occurs, (2) the point where runoff enters a well- defined channel, gully, terrace or diversion , or (3) where water leaves the field. The LS for the Cameo Refuse Disposal Area #1 is defined by the length and slope gradient of the lowest bench. The upper benches are excluded because the run -off encounters a bench where the slope decreases to the extent that deposition occurs. Shadscale Reference Area - LS Factor The LS factor for the Shadscale Reference area is based on an average 2.1 H:1 V Slope and an average vertical height of 166 feet and average length of slope is 347 feet based on five flow lines located in the reference area. The length of slope of run -off from the reference area was reduced to a length of 90.6 feet to make it comparable to the Cameo Refuse Disposal Area #1. Average Length 90.6 Feet Average Slope 47.6% Percent Slope (S) 40.0% 47.6% 50.0% 80 11.000 14.810 16.000 90.6 1 "LS" Factor 15.870 100 13.000 16.810 18.000 Cameo Refuse Disposal Area #1 - LS Factor The LS factor for the Cameo Refuse Disposal Area #1 is based on an average 2.76H:1 V slope at an average vertical height of 32.8 feet and an average length of slope of 90.6 feet based on five flow lines cut along the lowermost bench. Average Length 90.6 Feet Average Slope 36.2% Percent Slope (S) 30.0% 36.2% 40.0% 80 7.000 9.493 11.000 90.6 "LS" Factor 10.353 100 8.000 11.116 13.000 C (cropping - management) factors are the ratios of soil losses from lands cropped under specified conditions to the corresponding losses from tilled, continuous fallow. C factors for land uses other than cropland are included on Figures 7,8, and 9. The percent ground cover is the primary item to consider because a slight change in the percent ground cover will result in a significant change in the erosion prediction. Figure 7 - "C" Factors for Permanent Pasture and Rangeland ADJACENT AREA - "C" FACTOR Shadscale Reference Area No appreciable canopy. Canopy is assumed to be the cover contributed by trees and shrubs. Based on the 2010 Vegetation Evaluation the combined tree and shrub cover totals 2.7 %. The percent ground cover for the reference area shown above is 44.9 %. Use figure 7 identified above and interpolate to determine the C factor for 44.9% cover. CANOPY NO APPRECIABLE CANOPY PERCENT GROUND COVER 40.0% 44.9% 60.0% No G 0.100 0.086 0.042 appreciable Adacent "C" Factor 0.086 canopy A14 -13 -2 02/12