2015-10-13_REVISION - C1981014 (8)

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Page 3 Section 3.03.1 is represented by averaging the sum of the values for plant cover and litter cover in 2013 and 2014 taken from the RDA reference area, the Portal reference area, and the Old Portal reference area. The post mine, or reclaimed condition, was determined using the same method but by using the data as collected from the RDA reclamation, the Corley reclamation, and the Vento reclamation in 2013 and 2014. The cover values were again averaged for the three reclaimed areas. The C factor for the different vegetation types and cover were determined from Table 813.2, C factors for Permanent Pasture, Rangeland, Idle land, and Grazed Woodlands, found in Design Hydrology and Sedimentology for Small Catchments, Barfield Warner and Hayes, 1994. The values utilized are shown on Table 1. Mean Cover Reference Areas (non -mined condition) 2013 2014 Mean Plant and litter cover RDA reference area 70.27 75.33 72.8 Portal reference area 73.82 67.73 70.78 Old Portal Refer. area 63.52 83.9 73.71 Two year mean 72.43 Mean Cover Reclaimed Areas (reclaimed condition) 2013 2014 Mean Plant and litter cover Corley reclamation 65.47 77.34 71.40 Vento reclamation 75.8 65.47 70.63 RDA reclamation 80.08 82.2 81.14 Two year mean 74.39 Table 1 C Factors Area % Canopy and Type % C Height Ground Factor Cover Facility and RDA (reference area) 25% G 72.43% .0218 Facility and RDA (reclaimed area) 25% G 74.39% .0193 Support Practice Factor (P) The P factor represents the ratio of soil loss from any conservation practice to that with upslope and downslope tillage. It is used to evaluate the effects of contour tillage, strip -cropping, terracing, subsurface drainage, and dryland farm surface roughening. While a cover crop and seeding practices on the reclaimed area may have roughened the soil initially in the revegetation liability period, there is no support for any remaining effects of these conservation practices as compared to the non -mined reference area. For reclaimed and non -mined conditions a P factor of 1.0 was used. RESULTS The above input parameters were substituted into the RUSLE equation for both the reclaimed and non - mined condition. As shown below in Table 2, sediment yield for the reclaimed condition is slightly less than the non -mined condition for the Southfield Mine site and RDA.