2020-07-02_PERMIT FILE - C1981019A

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RULE 4 PERFORMANCE STANDARDS projections. As specified in the application,monitoring for these purposes shall consist of annual survey, utilizing field survey or aerophotogrammetric methods approved by the Division. Using maps depicting the annual surveyed configuration of the pit and reclaimed areas, the permittee will determine the overall overburden swell and the resultant variation between premining and post-mining topographic elevation for the mined areas. Further, the permittee will ascertain,record and report to the Division the proportions of overburden excavated using truck/shovel and dragline methods. The maps and a report presenting the methodology and results of the required determinations will be submitted to the Division for review and approval on an annual basis. The permittee will continue these monitoring procedures on an annual basis until the Division determines the results sufficient to adequately verify overburden swell factor projections and approves, in writing, cessation of monitoring. The maps will include a comparison of proposed and actual reclaimed contours and will be submitted annually throughout the permit term." Excerpted from Colowyo Findings and Proposed Decision to Approve Permit, File No. C-1981-019, September 28, 1982. The results of the monitoring can be found in the 1983 — 1982 Annual Reports. In the 1986 Annual Report, Colowyo requested a reduction in the overburden swell factor monitoring from an annual frequency to once every two and one-half years, and in a letter dated May 12, 1987 the MLRD stated that they were prepared to approve the reduction,which was made effective upon permit renewal. In the 1992 Annual Reclamation Report, Colowyo requested that the swell factor monitoring and analysis requirement be terminated. On August 11, 1993,Colowyo submitted a request for a minor revision to C-81-019 to facilitate the termination of this monitoring. The mining plan, as described in Section 2.05.3, is a soundly designed and engineered open pit mining plan, which maximizes coal conservation and recovery while minimizing adverse environmental impacts. Because of the multi-seam mining configuration planned by Colowyo, an exemption from the 180 day or four spoil ridge limitation remains necessary. The mining plan has been designed as a continuously moving open pit operation with the mine advancing approximately parallel to the dip of the numerous coal seams. The initial box cut for the operation was made on the south side of Streeter Draw. The mining operation is designed to progress in a southward direction with shovels/trucks/ proceeding along the entire length of the mining area uncovering the upper coal seams and the draglines uncovering the lower coal seams as shown on the mining range diagram (Map 24). With the numerous benches used in an open pit operation, the mine area will be opened for some time until the equipment comes back to initiate another pass on a designated bench. As the mining operations remove coal seams(In the southward progression),the mining area must be left open until such time as the lower-most coal seam can be recovered. With the mining configuration, the time differences between mining the upper-most seam versus the lower-most seam will obviously be greater than 180 days. As the operation advances, backfilling will be as contemporaneous as practical but not so as to interfere with removal of the lower-most coal seam. • Colowyo will rough backfill and grade as shown on the Spoil Grading Map (Map 29) by Rule 4 Performance Standards 4-43 Revision Date: 1/22/20 Revision No.: TR-136