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• 1.4.1 Regrading <br />Regrading would be the initial reclamation activity conducted at a mine if the operator permanently <br />ceased operations. The areas requiring regrade at Trapper Mine, if this improbable event occurred, <br />would be the open pks and associated spoil piles, roadways, impoundments, and ash disposal area, <br />Regrade costs are summarized in Table 1.4-2. Supporting calculations are shown in Tables 1.4-3 to <br />1.4-7. <br />1.4.1.1 Pit Regrading <br />The regrading costs for Trapper Mining Inc.'s ash disposal area, alive pits, and the final cut where <br />Derringer and Enfield pits come together, would require the largest expenditure of money as can be seen <br />from the tabulated dollar values. The cross sedions used to calculate the volumes shown in these tables <br />are included in Appendix A. The spoil diagrams that are the basis of the regrade sedions were <br />developed using Mincom software and are a relatively accurate depiction of pit geometry before regrade. <br />The cross sectional areas were applied to incremental pit lengths for the worst case year of 2004 in the <br />calculation of regrade volumes for each pit. The number of cross sedions constructed for each pit <br />tlepended upon the total pit length and the variability of overburden and interburden depths to a linear <br />change in depth. <br />• Conceptually, the backfilling of the open pits and elimination of highwalls would be accomplished by <br />using spoils from the two previous cuts plus the spoils from the current cut for a total of three spoil rows. <br />The F pit strikeline cut was a boxcut during the worst case year of 2004; therefore the boxcut spoils are <br />the only spoil row. It is important to note that this regrade work would also result in the final contouring of <br />aN ungraded spoils rows for each pit since mine regrade reclamation activities will always be within this <br />spoil row limit (refer to Section 3.5). <br />J <br />1-33 <br />