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For post-mining blocks, the USLE is calculated as: <br /> A(post)= (R)(K)(LS)(C)(P) <br /> = (30)(0.25)(8.11)(0.022)(1.0) <br /> = 1.34 tons per acre per year <br /> R 30 SCS Map of R factors for Colorado <br /> K 0.25 Trapper Permit C-1981-010 Appendix Q <br /> LS 8.11 SCS LS table; 719 feet, 16.7% <br /> C 0.022 SCS C factor for Permanent Pasture, Rangeland, Idle Land, <br /> and Grazed Woodland — no canopy, 73.6% herbaceous <br /> cover, grass type (Table 1.2-1 of Bond Release submittal) <br /> P 1.0 SCS P factor <br /> The USLE demonstrates that the existing condition of the reclaimed blocks results in equal or lesser <br /> sediment contributions to surface runoff as compared to pre-mining conditions on an annual basis. <br /> 1.4.2 SEDCAD 4 <br /> Trapper has developed a site drainage and sedimentology model to estimate the total quantity of sediment <br /> produced from a storm event for the runoff from each block under pre-mining and post-mining conditions. <br /> The block drainage and sedimentology models were developed utilizing SEDCAD 4 for Windows, a <br /> computer software program developed to assist in the evaluation of stormwater runoff, erosion, and <br /> sediment control management techniques. <br /> To develop representative models of the pre-mining conditions in each block, baseline information from <br /> the permit was utilized as input data in the SEDCAD 4 program. To develop comparative models <br /> representing existing conditions for each block, the vegetation survey information outlined in Section 1.2 <br /> was utilized as input into the SEDCAD 4 program with input parameters modified as appropriate in <br /> accordance with this information. Given the irregular shapes of the blocks in relation to the topography <br /> and recognizing that portions of individual blocks may fall within adjacent sub-watersheds, it is difficult to <br /> develop specific pre and post-mining runoff models for each entire block. In order to develop <br /> representative and comparable runoff models, typical twenty-acre sections of each block were modeled <br /> using the average slope and slope length for the entire block. A summary of the SEDCAD 4 program <br /> 12 <br />