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West Etk Mine <br />two-seam (Apache Rocks) mining (i.e. mining sequence, mine layout, etc.) aze discussed in <br />Sections 2.05.2, Operation Plan. <br />Groundwater can be classified in the coal measures as occurring in the active and inactive zones <br />as it relates to the genesis, composition, and storage of the water. Active and inactive zone <br />groundwater systems have been described in the peer reviewed literature by Mayo and others <br />(2004) as follows: "Active zone groundwater flow paths are continuous, responsive to annual <br />recharge and climatic variability and have groundwater residence times "ages" that become <br />progressively older from rechazge to dischazge area." "Inactive zone groundwater has extremely <br />limited or no communication with annual recharge and has groundwater mean residence times <br />that do not progressively lengthen along the flow path. Groundwater in the inactive zone may be <br />partitioned, occur as discrete bodies, and may occur in hydraulically isolated regions that do not <br />have hydraulic communication with each other." The active water zone includes the neaz surface <br />waters derived from rain and snowmelt stored in the neaz surface colluvium, alluvium and near <br />surface bedrock formations (generally less than 500 feet in depth). Surface water inflows aze not <br />expected to impact E Seam mining. <br />Groundwater in the inactive zone is ancient stored water residing in sand channel bodies, within <br />the porous sections of fluvial or marine sand lenses, or within the damaged zones of fault and <br />fracture systems. The strata containing water surrounding the West Elk Mine region has ancient <br />water in the inactive zone that has been age dated to approximately 10,500 years. The age is <br />consistent with similar non-tributary water found in coal mines of the Wasatch Plateau and Book <br />Cliffs of Utah. Melt off of Pleistocene glaciers from the West Elk Mountains south and east of <br />MCC's coal lease holdings provided an ample source of water of the appropriate age as the <br />source for the inactive zone water. <br />In the E Seam, inactive groundwater inflows aze expected to occur as: <br />1. Roof inflows from sandstone channels located in the E Seam roof. Inflows from overlying <br />sandstone channels could issue from roof bolt holes, vertical borings, or the bottoms of channels <br />exposed during mining. Flow rates of 10 to 15 gpm expected. <br />2. Floor inflows occurring as springs from the Bowie Sandstone. Maximum projected inflow of <br />200 gpm possible. <br />3. Roof and or floor inflows issuing from damage zones associated with tectonic faulting as <br />discussed above. These damage zone inflows can significantly increase the inflow rates and <br />total volumes of flows associated with marine sandstone springs and sandstone roof channels. <br />Maximum projected inflow of 500 gpm possible. <br />The water drained by tectonic fault systems resides within the dilated faults and fractures of <br />competent sandstones, primarily the Rollins Sandstone with lesser amounts stored in the Bowie <br />Sandstones. Each fault system is independent of each other for storability. hi the B Seam newly <br />encountered fault zones will rapidly drain water from the most open fractures of the underlying <br />Rollins Sandstone and overlying Bowie Sandstones. The flow rates diminish as the water travels <br />through more tortuous paths of less dilated damage zone fractures and as the fractures above the <br />1.05-119 Revised November 1004 PRIO <br />