2022-09-29_PERMIT FILE - C1980007 (2)

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Wes[ Elk Mine • Using actual B Seam permeability values from MCC slug tests, permeability data range from 4 x 10-6 to 5 x 10-s cm/sec. With a five percent hydraulic gradient, the calculated "worst case" sump seepage rate is estimated to be approximately 0.7 to 8.4 gpm. Empirically, the outflow will be nonexistent. MCC's own experiences within West Elk Mine support the very low permeability of the B Seam, perhaps below the lowest value of the range calculated from slug test data (0.7 gpm). Specifically, there were relatively dry coal faces just prior to mining through the high-pressure fault inflow areas; and most importantly, after drilling the NW sump #1 horizontal drill hole 215 feet, water was first encountered in the hole only 17 feet from the filled sealed sump (with approximately 65 feet of head). Potential Impacts to Down~radient Mine Workings Operators of the Bear No. 3 Mine erroneously alleged in their annual hydrology reports since 1994, that sumping of water within MCC's sealed NW longwall panels caused minor inflows of up to 30 gpm in the Bear Mine's Third West azea, disregarding their actual encounters with fractures and water when mining neazby within the Bear No. 3 Mine. Also disregazded was the fact that both Bear and MCC experienced wet conditions, including seeps and inflows when mining in the same vicinity beneath the Lone Pine Gulch drainage. In addition, MCC completed detailed analysis of projected outflows and flow paths within the Bear Mine based on two scenarios -storage volumes of 10 acre feet (purple shading on Figure 28) and 30 acre feet (blue shading). These numbers essentially bracket the volumes of water that would accumulate in longwall panels INW through SNW based on the estimated inflow rates of 5 to 10 gpm occurring from May 1995 to November . 1996 (i.e, 5 gpm for 18 months = 12 AF, and 10 gpm for 18 months = 24 AF). For water accumulating at the northeast corner of INW, the maximum potential outflows to the Beaz No. 3 Mine were calculated for volumes of 10 and 30 AF. At 10 AF (purple shading), there would be no water tributary to the Beaz Mine. At 30 AF (blue shading), the total potential seepage from the sump would be approximately 1 gpm, with less than half being tributary to the Beaz Mine. Similaz calculations were performed for water accumulating at the northeast corner of SNW. This location is important since Beaz staff reported a wet rib down-dip from this location about March 1995. Even at 30 AF (blue shading), the maximum potential outflow is less than 1 gpm and water could not accumulate in SNW at this location until May 1995, when MCC completed sealing of the 1NW through 5 NW Panels. The value of less that 1 gpm should be contrasted with the observed inflows at seals in the Beaz Mine in June 1995 of 18 gpm. It was also noted that these calculations based on Dazcy's Law are for sump outflows and not Beaz Mine inflows; the travel time through the unmined coal block has not been accounted for to simplify the analysis. As such, Beaz's observed inflows, as reported in their AI-1R's, cannot be accounted for by MCC's water management practices. Beaz's reported inflows were observed at the Third West seals and the Second West bleeder seals. WWE performed hydraulic calculations to determine the maximum potential outflow from the filled sump to these locations. The portion of the filled sump that could emerge at the Third West seals is shown as location A on Figure 28. The portion of the filled sump that could emerge at the Second West bleeder seals is shown as location B. The maximum outflow 2.05-187 Revised/une 2005 PR70; Rev. March 1006; Rev. May 2006 PRIO