2025-06-30_PERMIT FILE - C1981019A (2)

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RULE 4 PERFORMANCE STANDARDS Collom – Rule 4, Page 16 Revision Date: 4/28/22 Revision No.: TR-154 4.10 – 4.12 COAL MINE WASTE BANKS, COAL MINE WASTE, SLIDES AND OTHER DAMAGE These sections are addressed in Volume 1. 4.13 CONTEMPORANEOUS RECLAMATION All reclamation efforts, including backfilling, grading, topsoil replacement and revegetation of land disturbed by the mining activities in the Collom pit shall occur as contemporaneously as practicable with mining operations. Implementation of the reclamation plan, as described in Section 2.05.4, will assure that each step in the reclamation process is completed in a timely manner. Colowyo is formally requesting a variance for a delay in contemporaneous reclamation in the Collom Pit mining areas as the requirements listed in Rule 4.14.1(1)(d) are unachievable. The sequence for reclamation following the mining process is shown on Map 29B (Spoil Grading – Collom). Final reclamation of the Collom Pit will continue through 2033. An excess overburden pile out of pit) will be needed during the initial years of mining to establish the initial boxcut configuration for the Collom Pit. Full establishment of the Collom Pit Boxcut should occur approximately five years after mining is initiated and backfilling activities will begin during that timeframes illustrated on Map 29B. At that time, spoil regrading and subsequent reclamation activities will accelerate. As activities progress, a sufficient volume of backfill void will be created, and the Collom Pit should reach a steady state of operation where the advancing overburden face moves southward at the same rate as the advancing backfilling benches. The excess overburden pile is expected to remain in place until the final years of mining activities. At that time, this material will be needed to fill the final pit void. Colowyo is currently targeting multiple coal seams in the box cut area and a single seam outside the box cut area. Because of the multi-seam nature of the mining operation described in Section 2.05, backfilling and grading cannot be completed within 180 days following coal removal within the boxcut area. Backfilling and grading will be completed in variance of the 180 day requirement in a manner previously approved and described below, and in Sections 2.05 and 4.14.1. A series of benches will be necessary in the operation to recover the lower coal seams, and an additional series of benches will be necessary to dump the shovel/truck overburden material in a configuration that achieves the topography shown on the post-mining Topography Map (Map 19C). When multi-seams are mined, backfilling and rough grading cannot begin until the lower-most seam is mined. See Spoil Grading Map (Map 29B), which shows the time frames in which grading will occur in relation to the mine plan (Map 23B). Further, highwall mining is planned to occur with the center potion fo the Collom Pit, and that area needs to remain free of backfill and grading until highwall mining in completed. As mining progresses to the south, overburden material from each successive cut will be backfilled into the previously mined out area if space is available and the additional spoil will continue to buildup in previously mined areas. Initially an excess out of pit spoil pile will be created to the north of the Collom Pit and will remain in place until the end of mine life. 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 19C). Colowyo will grade all final slopes so that overall grades do not exceed 3H:1V (Map 20C). Where necessary, the regraded spoil surface will be roughened by ripping or discing etc., to ensure a bond between the topsoil and spoil to reduce slippage and to allow vegetative root penetration. To date there is no evidence of topsoil slippage on reclaimed areas in the existing permit area. A few small tension cracks