2020-03-24_PERMIT FILE - C1981019A (2)

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RULE 2 PERMITS South Taylor/Lower Wilson – Rule 2, Page 76 Revision Date: 2/13/19 Revision No.: TR-135 The reclamation plan for the existing mining areas provides information relevant to the reclamation of the South Taylor mining area, which can be found in Volume 1, Section 2.05.4. Specific topics requested by the regulations and not incorporated into Volume 1 are included in the following subsections. 2.05.4 (2)(a) Reclamation Timetable The sequence for reclamation following the mining process is shown on Map 29. Final reclamation of the South Taylor pit will be delayed, due to the shape, size and depth of the pit; which will result in leaving the majority of the spoil backfilling process until final pit closure. The majority of the spoil will be stacked in the initial boxcut area and associated valley fill areas, allowing adequate space to perform mining operations in a geotechnically safe environment. Although the final reclamation of the South Taylor will be delayed due to the mining operations in the pit, Colowyo is committed to reclamation in accordance with Rule 4.13 and will perform reclamation activities as contemporaneously as practicable with the South Taylor mining operations. With the limitation of areas available for reclamation prior to final pit backfill, Colowyo will reclaim as many areas as allowed by the mine plan as shown on Map 29, prior to final pit closure. The South Taylor pit reached a steady state operation in 2013; where as all spoil material produced in the advancing cut is backfilled into the previously mined areas. In general, it is anticipated that the vast majority of reclamation activities in the South Taylor pit area will begin in the lower elevation areas and progress upslope to the highest elevation areas. This is a matter of practical necessity due to the operational constraints encountered in the area which were also reflected in the hydrological modeling found in Exhibit 7, Item 20. Major departures from this premise will result in the need to revisit the adequacy of the sediment control structures designed and submitted as part of this permit. 2.05.4 (2)(b) Reclamation Costs The estimate of the cost of reclamation of the operations required to be covered by the performance bond is found under Rule 3. 2.05.4 (2)(c) Backfilling Plan As the mining progresses to the west, overburden material from each successive cut will be backfilled into the previously mined out area and the additional spoil will continue to buildup in previously mined areas. This cycle will be repeated for the entire mining area. Due to shape, size and depth of the South Taylor pit results in leaving the majority of the spoil backfilling process until final pit closure. As a result, Colowyo has been granted a variance for a delay in contemporaneous reclamation based on Rule 4.14.1(1)(d) which states that “Rough backfilling and grading shall be completed within 180 days following coal removal and shall not be more than four spoil ridges behind the pit being worked..”. The mining techniques utilizing dragline and truck/shovel operation are shown in detail on Mining Range Diagram (Map 24B), and show the approximate distance between topsoil removal and replacement. Premining topography is presented on Map 18A and the postmining topography is shown on Map 19B. Map 20B provides cross-sections of the premining and postmining topography. Map 28 presents the topsoil handling movements and the timing of stripping activities. Map 29 shows the spoil grading sequence timing of reclamation activities. The backfilled mining areas will be graded to establish a stable post mine topography that blends into the undisturbed areas outside the mining limits (Map 19B). Colowyo will grade all final slopes so that overall grades do not exceed 33% (Map 20B). Additional information on the backfilling and regrading plan are discussed further in Volume 1, Section 2.05.4 and Section 4.14.