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For post -mining blocks, the LISLE is calculated as: <br />A(post) = (R)(K)(LS)(C)(P) <br />= (30)(0.25)(6.83)(0.014)(1.0) <br />= 0.72 tons per acre per year <br />R <br />30 <br />SCS Map of R factors for Colorado <br />K <br />0.25 <br />Trapper Permit C-1981-010 Appendix Q <br />LS <br />6.83 <br />SCS LS table; 675 feet, 15.3% <br />C <br />0.014 <br />SCS C factor for Permanent Pasture, Rangeland, Idle Land, <br />and Grazed Woodland — no canopy, 79.3% herbaceous <br />cover, grass type (Table 1.2-1 of Bond Release submittal) <br />P <br />1.0 <br />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 />inputs and results for both the pre -mining and post -mining land conditions are shown on Tables 1.4-1 and <br />12 <br />