2022-02-22_PERMIT FILE - C1980007 (5)

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West Elk Mine 2.04-46 Rev. 11/04- PR10, 04/06- PR10, 09/07- PR12, 10/08- PR14; 01/22- MR459 instances, significant water bearing fault system (2000gpm) was crossed. The coal 10’ to 15’ away from the fault systems did not exhibit any additional water flows or leakage. Within the fault damage zone, fractures in the roof and floor strata allowed for minor water leakage from the main fault conduit. However, no perceptible water flow through the coal seam occurred except for within the fault blades where the crushed and brecciated coal exist ed. If the coal seams were permeable and transmissive, theses fault zones would be depressurized and mostly drained with obvious increases in water flows in a wide halo around the fault zones. The B Seam roof is predominately mudstones with occasional coal riders and fine grain laminated sandstones. More sandstone overlies the B Seam than the E or F Seams, but this sand appears to be more of tabular or sheet-type sand and does not hold much perched water. Also, the immediate roof shales are harder, less slickensided, and are more stable in the presence of any water encountered. The D through F Seam coals conformably overlie the Bowie Sandstones. The strata containing the coals are fluvial in nature containing a mixture of sandstone channels, overbank splay deposits, fine-grained siltstones and mudstones, and carbonaceous mudstones with minor coal layers. Only the E Seam sandstone roof channels are considered to be a significant water source. Mayo (2004) estimated the maximum inflow rate from non-faulted sandstone channels to be 500 gpm diminishing gradually over 6 months. Water inflows from tectonic faults and their associated damage zones have been well documented in the B Seam mining. These northeast – southwest trending faults are known to be sufficiently dilated to provide a conduit for sporadic groundwater movement. Prior to 1996, several fractures and faults encountered within West Elk Mine produced water at a maximum initial rate of 50 to 100 gpm for a couple of days before diminishing to a few drops or a wet area. These fractures and faults generally contained a finite amount of storage volume with limited recharge. Based on Mayo’s work (1998, 2000, 2003, and 2004) the water drained by tectonic fault systems resides within the dilated faults and fractures of competent sandstones, primarily the Rollins Sandstone, with lesser amounts stored in the Bowie Sandstones. Each fault system is independent of others relative to storability. Newly encountered fault zones will rapidly drain water from the most open fractures of the underlying Rollins Sandstone and overlying Bowie Sandstones. The flow rates diminish as the water travels through more tortuous paths of less dilated damage zone fractures and as the fractures above the elevation of the mine opening are drained. The inflows from the faults reach equilibrium at 50 to 125 gpm, existing as floor springs until the fault zone is breached at a lower elevation by subsequent development. Down - dip inflow rates from the fault zones are dependent upon the displacement and damage zone extents, the incremental head (vertical elevation change), and linear distance from the last fault intercept. Each new down-dip intercept dries up the previous floor spring. Up-dip inflows from the faults have been limited to short-lived nuisance roof water at less than 10 gpm, with no sustained water flows from the faults. Since 1996 four significant inflows (>2,000 gpm) from two major fault systems have been encountered in the B Seam mining. The first fault inflow from the B East Mains Fault (BEM)