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West Elk Mine mining in the B seam are included and are based on data and evaluations of the F seam subsidence, as well as current industry data for the mining methods employed. A subsidence monitoring plan to monitor mining in the B seam for the 5-year permit area is included in Exhtbit 60. The monitoring plan will provide additional data which when coupled with the F seam data and can be utilized for future mine planning considerations. Conventional ground surveying techniques are applied for surveying the monitoring network. The surveys are designed to achieve horizontal accuracies complying with the U.S. Department of Commerce's "Second order, Class II" surveying standards, and vertical accuracies no less than ± 0.2 feet. Grids are surveyed twice prior to the initiation of subsidence. A minimum of six triangulation bench mark monuments outside the area of anticipated subsidence effects were selected and established. Mountain Coal Company will adhere to these requirements for future surveys. Subsidence monitoring reports are submitted oo asemi-annual basis in a format approved by the Division. The effect of mining-induced subsidence on renewable resources, structures, and geologically unstable areas in the 5-year permit area is discussed in a report entitled Subsidence Evaluation for West Elk Mine. This report is included in this Mining and Reclamation Plan as Exhibit 55. A limited mining buffer zone has been designed to protect the Dry Fork of Minnesota Creek and is included as Appendix B to Exhibit 55 and shown on Map 50. When a mine plan is submitted to undermine the Dry Fork, this subsidence protection plan will be evaluated and altered, if necessary, based upon subsidence data collected during earlier mining. Until approved by CMLRD, Mountain Coal Company will not mine under or adjacent to any perennial streams. Additionally, there exists on or near the property no aquifers that supply any public water system or any public buildings as described in CMLRD's Regulations for Coal Minin¢. All surface owners will be notified by mail at least six months prior to mining beneath their property. Mining will not approach the two perennial streams--South Prong and Horse Creek-- until 25 to 35 years into the mine life. These streams will be protected, at a minimum, by buffer zones similar to that designed for the Dry Fork. A crack reported by Dunrud (1976, p. 14) to be 1.5 feet wide and 515 feet above the coal workings at a site approximately 3 miles from the proposed site occurs at 485 feet of overburden thickness, with a greater concentration of cracks at or below the 400 feet thickness. With one exception all cracks shown in Dunrud's figure 14 occur where the overburden is less than 500 feet thick. The principal areas of sub-500 foot cover at West Elk are near the outcrop and under the Dry Fork of Minnesota Creek. These areas will be 2.05-147 Revived November 1992 I~~UL ~~~