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According to CDRMS Regulation 4.15.8(3), Phase II bond liability release will be <br />considered acceptable if the vegetative establishment on the reclaimed land <br />meets the requirement of 90% herbaceous cover of the reference area standard <br />with 90% statistical confidence. See Exhibit 5 for information addressing <br />vegetation establishment and sample locations. <br />According to CDRMS Regulation 3.063.1(3)(b), bond liability release cannot be <br />granted until the applicant demonstrates that the existing revegetated area will <br />result in equivalent or lesser sediment contributions to surface runoff when <br />compared with pre-mining levels as determined by baseline data. See Section <br />4.0 and Table 4 for the demonstrations addressing hydrology. <br />4.0 Sediment Control Demonstration <br />4_1 Hydrology Summary and Methods <br />The purpose of this section is to demonstrate that the completed revegetation <br />and grading in the reclaimed areas for which Phase II bond release is being <br />sought has achieved erosion control at lease equal to pre-mining levels, as <br />required in Rule 4.15.1 (2) (b), and that suspended solids delivered to streamflow <br />outside the permit area will not exceed pre-mining levels, as required under Rule <br />3.03.1 (3) (b). <br />The methodology used is the Revised Universal Soil Loss Equation (RUSLE), <br />using site specific soil and vegetation data and slope measurements based on <br />pre-mining and post-mining topographic maps. <br />The RUSLE was used to calculate average annual sediment erosion, in <br />tons/acre/year, based on the equation <br />A = R K LS C P, where <br />A = gross erosion in tons/acre/year <br />R = erosivity index of local rainfall <br />K = soil erodibility actor <br />LS = length/slope factor <br />C = vegetative cover factor <br />P = management practice factor <br />Phase l and 11 Bond Release Application 13