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Doc Date:1 211 112 0 0 1 II I III I II I II IIII III <br />sss <br />5 /~ •3.4 HACKFILLING fi GRADING <br />3.4.1 BACKFILLING METHODS AND EQUIPMENT <br />Backfilling of all pits, except for the final pit in a given mining <br />area was accomplished by the equipment previously listed in Table 3.1-1, as <br />overburden removal equipment. The final pit in each mining area used <br />conventional bulldozing equipment. When the overburden was removed by the <br />dragline or the backhoes, backfilling was done by casting the material into <br />the adjacent, previously mined pit. Material removed by scrapers or <br />backhoes when placed in trucks, was hauled to nearby pits where it was <br />deposited in a manner that roughly approximates the premining surface. <br />This minimized the effort necessary for grading. An exception to these <br />methods was the box cut spoil handling in the Moffat Area shown on Exhibits <br />3.3-3 and 3.3-9. <br />Since no acid-forming or toxic-forming material was found (Section <br />2.2) and no aquifers were found (Section 2. 5) in the area to be mined, no <br />selective spoil handling was necessary. Therefore, backfilling intermixed <br />overburden in whatever manner best established the proposed postmining <br />topography. <br />• 3.4.2 GRADING METHODS AND EQUIPMENT <br />Grading employed conventional bulldozing equipment. In certain <br />instances, grading was aided by trucks, scrapers and the overburden removal <br />equipment. <br />3.4.2.1 Moffat Area Grading Plan <br />Material was moved across the hill with the exception of the <br />overburden from the initial and final cuts. All box cut spoils along the <br />southern edge of the mining area were cast southward. The box cut spoil <br />grading overlapped onto previously mined ground from which no topsoil was <br />available for salvage. Grading began along the south end of the box cut <br />area once adequate operating room existed between the active pit and the <br />grading area. Grading was performed in a manner to maintain a minimum <br />buffer zone of 100 feet of undisturbed ground between Trout Creek and the <br />active grading area. <br />In accordance with the Colorado Mined Land Reclamation Board Rules <br />• and Regulations, a stability analysis was performed on the box cut spoil <br />placed on the previously mined East Ridge spoils. The analysis <br />Renewal-3 3.9-1 June 13, 1997 <br />