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(~iov 22 OS 08:12a Edith Savage <br />303 665 6808 <br />The LS factor calculated for the reclaimed areas at the mine was based on slope <br />measurements taken during the vegetation field sampling (see accompanying table). Based <br />on a 0.885° mean reclaimed slope and an average slope length of 507 feet, a LS factor of <br />1.67 was calculated. Using the equation again with average slope lengths and <br />measurements taken from the adjacent natural topography (2°, and 742 foot slope length), <br />a LS factor of 5.23 was calculated for the adjacent undisturbed area. <br />Slope Angle aad Length Data by Location <br />Area Slope angle (degrees) <br />1 0.41 <br />Slope Length (feet) <br />500 <br />3 0.27 1050 <br />8 1.32 ~ 650 <br />14 0.98 350 <br />18 1.29 620 <br />21 0.9I 500 <br />24 2.29 200 <br />26 0.46 500 <br />27 0.46 500 <br />28 0.46 200 <br />Mean 0.885 ~ 507 <br />COVER FACTOR (C) <br />The cover factor in the USLE equation accounts for the effect of plant and litter cover on <br />the ground surface in reducing erosion by intercepting raindrops and reducing direct <br />contact with the soil. For the varying vegetation types such as that at the Keenesburg <br />Mine, Table 1 was used in conjunction with the 2004 vegetation data to develop the <br />appropriate factors. <br />At the undisturbed adjacer sandsage community, the vegetative covet is a mixture of low <br />to moderately sized sand sage interspersed with grasses and forbs. The grasses aze either <br />warm season bunch or sod-formers. This community falls into the category of <br />communities with a canopy of tall weeds or short brush. The canopy coverage of the sand <br />sage community falls between 25 and 50 percent, and the community is dominated by <br />grass. The percent of ground cover contacting the surface is approximately 60 percent <br />(total vegetation cover minus woody plain canopy cover plus litter). From this <br />characterization acover value of 0.036 was interpolated from Table 1. <br />Within the reclaimed areas, the mean (1995 and 1997 reclaimed azeas) total vegetation <br />cover (40%) is comprised ]argely of sod-forming and bunch grasses with spreading bases, <br />and standing litter. These types of vegetatiot provide significant cover <br />p.7 <br />Coors Energy Company Keeneeburg Mine Paee 4 <br />Phase II Bond Release 5edlmerrtobgy Demonstration <br />