2018-09-04_PERMIT FILE - C1981019A

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RULE 4 PERFORMANCE STANDARDS Reports, the stripping accomplished by draglines can vary from 40% to 45% and from 55% to 60% for truck/shovel. Swell factor will continue to be monitored and the postmining topography adjusted, if necessary. Any adjustments will be minor, will be done gradually and will not affect the reclamation plan or postmining land use. Particularly, drainage channel gradients will not be changed; an entire drainage channel elevation could possibly be revised, but the gradient would remain as designed. If a change would be necessary, the dump plan elevations would be revised as appropriate. In order to verify accuracy of the overburden swell factor predictions and postmining topography projections in the initial permit term, Colowyo has committed to the following requirements: "The applicant has committed, within the application to monitor the topographic configuration of the pit and the postmining reclaimed surface of the mined area, in order to verify the accuracy of the overburden swell factor and postmining topography 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 Rule 4 Performance Standards 4-42 Revision Date: 5/25/18 Revision No.: RN -07