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Page 6 <br />considered successfully reclaimed if the total vegetation cover (percentage) is not less than 90 percent of <br />y in the following equation: <br /> <br />y = -0.0127x3 + 0.2115x2 + 2.1772x. <br /> <br />In the equation, x is the September – July precipitation (in inches) during the previous year. <br /> <br />The bond release block requested in SL-12 has a post-mining land use of rangeland. <br /> <br />CEC used the Revised Universal Soil Loss Equation (RUSLE) to demonstrate acceptable soil loss on the <br />reclaimed lands. The Division has previously approved CEC’s use of this model for the Keenesburg <br />Strip Mine to demonstrate acceptable sediment loading from the area to be released. Furthermore, this <br />methodology has been widely used for Phase II bond release applications at other Colorado coal mines. <br /> <br />PHASE III <br /> <br />Rule 3.03.1(2)(c) states, "The remaining portion of the bond amount shall be released when the <br />permittee has successfully completed all surface coal mining reclamation operations in accordance with <br />this approved reclamation plan, and the final inspection and procedures of 3.03.2 have been satisfied. <br />This shall not be before the expiration of the period specified for revegetation responsibility in 3.02.3." <br />Rule 3.03.1(4) states, "No bond shall be fully released until all reclamation requirements of these Ru les <br />and the Act are fully met...". The same rule goes on to state, "No acreage shall be released from the <br />permit area until all surface coal mining and reclamation operations on that acreage have been <br />completed in accordance with the approved reclamation plan." <br /> <br />In addition to the Rules, the Division used the Keenesburg Strip Mine PAP to assess reclamation <br />success. <br />Drainage Control and Reestablishment <br /> <br />In the bond release area for SL-12, there are no drainage control structures. <br />Topsoil Replacement <br /> <br />For Phase III bond release applications, no particular criteria are considered for topsoil. However, the <br />replacement of topsoil can be assessed in the context of the overall success of the reclamation, including <br />the presence of erosion (or lack of erosion) and the health of the vegetation. <br />Revegetation <br /> <br />Vegetation success standards for the area are as follows, taken from Section 2.05.4 of the PAP: <br /> <br />Total Vegetation Cover. Reclaimed areas will be considered successfully reclaimed if the total <br />vegetation cover on the reclaimed area(s) is not less than 90 percent of the total vegetation cover value <br />from the equation: y = -0.0127x3 + 0.2115x2 + 2.1772x (where x is the cumulative September – July <br />precipitation at the mine) with 90 percent statistical confidence using a one-tailed Student’s t or