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1.4.1 Rearadin <br />Regrading would be the initial reclamation activity conducted at a mine if the operator <br />permanently ceased operations. The areas requiring regrade at Trapper Mine, if this <br />improbable event occurred, would be the open pits and associated spoil piles, roadways, <br />impoundments, and ash disposal area. Regrade costs are summarized in Appendix A, <br />Table A-3. Supporting calculations are shown in Tables A-4.1 through A-4.5. <br />1.4.1.1 Pit Regrading <br />The pit regrading costs for Trapper Mine include the current ash disposal area (Ash Pit), Zs <br />Pit, K, L, M pits, AE pit, and the final cut where Derringer (D) and Enfield (E) pits come <br />together. The final cut in D and E pits has been permitted as an ash disposal area. For <br />reclamation liability purposes, it is assumed that there is no ash in the D/E ash disposal <br />area. <br />Conceptually, the backfilling of the open pits would be accomplished mainly through grading <br />of highwalls and spoils with dozers and would require some blasting and highwall reduction. <br />The cross sections used to calculate the volumes shown for all pits in the regrade tables are <br />included in Appendix A. The spoil diagrams that are the basis of the regrade sections were <br />developed using Mincom software, and are a relatively accurate depiction of pit geometry <br />before regrade. The cross sectional areas were applied to incremental pit lengths for the <br />worst case year of 2014. The number of cross sections constructed for each pit depended <br />upon the total pit length, and the variability of overburden and interburden depths. Dozers <br />would do the backfilling and grading as this is the most cost efficient equipment other than <br />draglines, given the average distances calculated. Caterpillar D11 R dozers were selected <br />as the most efficient equipment to complete the regrading task. Some scraper work was <br />required to backfill the KLM pits, and to insure positive drainage. <br />Pits will be backfilled using spoil material currently available within existing spoil rows <br />associated with each pit. Appendix A provides appropriate cross sections of existing and <br />regraded post -mine topography. <br />1.4.1.2 Roadway Regrading <br />For purposes of estimating reclamation cost, three types of roads have been identified at <br />Trapper Mine, which include access, haulage, and dragline walk roads. These roadways <br />are designed and constructed to minimize amounts of cuts and fills, which minimizes the <br />amount of backfilling and grading that would be necessary to return them to a satisfactory <br />contour. Caterpillar D10R dozers were selected as the most cost efficient equipment, given <br />the average distances calculated. These push distance and volume calculations for the <br />roadways are based upon typical cross sectional areas. These areas were applied to <br />projected road lengths during the worst case year of 2014 as shown on Map M9. From <br />these values, regrade times, as shown in Table A-6, were calculated. Costs were also <br />included for ripping haulroads using a material seismic velocity of 5000 fps. <br />Trapper is careful not to introduce materials on roads that will require removal at a later <br />date. That is specifically why the use of ash on haul roads has not been pursued. Roads <br />are constructed of earthen fill and sub -base material with gravel on top. Scoria may also be <br />used if available. These inert materials are easily graded during reclamation, covered <br />withtopsoil, and do not adversely affect the growth of vegetation. Post mining land use <br />requirements are not compromised. <br />1-34 <br />TA a,( 111 ( 7,013 <br />