2022-06-13_PERMIT FILE - C1980007

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West Elk Mine 2.04 -63 Rev. 06/05- PR10, 03/06- PR10, 04/06- PR10, 09/07- PR12; 05/22- MR462 confirmed in core plug analysis of samples between the A and B Seam coals by Mayo and Associates (1998). Based on observations during drilling and development of well SOM-3E the permeability of the B-Seam is estimated to be about 2.3x10-3 ft/day (1x10-6 cm/sec) (HydroGeo, 2003). Upper Coal Member (Mesa Verde Formation) The Upper Coal Member contains approximately 230 feet of interbedded shales, siltstones, lenticular sandstones, and three persistent coal seams. These seams include the D, E, and F coal seams. In portions of the Apache Rocks permit area and all of the South of Divide permit area, the E Seam was determined to be of sufficient thickness and quality to be mined. This stratigraphic member of the Mesaverde Formation lies between the underlying marine sandstones (principally the Bowie Sandstone) and an overlying, similar but less persistent, massive, cliff-forming discontinuous channel sandstone. Groundwater inflows into the E Seam workings were projected to occur from two potential sources: 1. Sandstone channels in and near the roof of the E Seam workings. 2. Fault-related inflows from the underlying Bowie Sandstone. Extensive sandstone channels were mapped above the E Seam in the South of Divide permit area. The extent of these sandstone channels was presented in Exhibit 18B on Figure 17. Because 800 or more feet of overburden generally covers the channel sandstones, it is unlikely that they have received appreciable recharge by vertical infiltration from the overlying rocks or are in active hydraulic communication with either surface water or near surface groundwater (Mayo and Associates, 1999). The most likely recharge locations are along up-dip regions in the vicinity of Minnesota Creek and possibly near the contact with the Mt. Gunnison intrusion. However, no known sandstone channel outcrops have been positively identified along the Minnesota Creek drainage due to colluvial cover. While monitoring well data have documented saturation in these channel sandstones, appreciable quantities of water or unusual water pressures have not been encountered in the numerous boreholes that have penetrated these channels. In addition, no water was encountered when constructing three ventilation shafts, numerous mine ventilation boreholes, or in the development workings and longwall panels mined in the SOD area in the E Seam. Inflows from these sandstone channels are expected to be minor, but in association with faults such as the 14 HG could be as great as 500 gpm. Damaged zones associated with these fault zones have the potential to locally increase both the permeability and storage capacity of the sandstone channels thus potentially increasing roof inflows in the vicinity of the faults. Such roof inflows are not expected to persist for more than a few weeks (see Exhibit 18B). Mayo and Associates Exhibit 18B describes the Bowie Sandstone as having a similar depositional history and mineralogical composition to that of the Rollins Sandstone. As a result, fault-related inflows from the Bowie Sandstone beneath the E Seam have the potential to be as great as those associated with the Rollins Sandstone. However, given the lack of continued significant roof inflows into the B Seam workings, it is thought that most, if not all, of the saturation within the Bowie Sandstone near the fault zones encountered by the B Seam workings have been drained. Only a few minor seeps discharge from Bowie Sandstone outcrops between