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West Elk Mine <br />(and groundwater use) at the mine and surrounding properties. Domestic water for mine use is <br />supplied by surface water from the North Fork. <br />There are essentially three ways in which mining activities at West Elk Mine can affect <br />groundwater quantity. These include: (1) the construction of mine entries, (2) the direct mining <br />of the coal (this includes the effect of roof collapse and mine subsidence on water-bearing <br />formations above the coal and the interception groundwater in damaged fault zones), and <br />(3) the storage of water in previously mined and sealed portions of the mine. These are <br />discussed in turn. <br />Construction of Mine Entries <br />Access to the B Seam is by two sloped entries driven from the F Seam South Main Intakes. <br />Access to mining within the current permit and South of Divide permit revision azeas, and <br />subsequent mine development, is also planned via these same sloped entries. <br />Mine exhaust air is currently routed westwazd through the B Seam to the Lone Pine ventilation <br />fan, as well as through the F Seam, via aninter-seam ventilation raise, then to the Sylvester <br />Gulch ventilation fan. Mine intake air enters the mine at three locations: (1) F Seam Portals, (2) <br />Lone Pine Portals, and (3) Shaft #3 in Sylvester Gulch. The lazgest of these ventilation facilities <br />is located in Sylvester Gulch where two lazge diameter shafts serve both present and future <br />intake and return ventilation needs for the B Seam and E Seam mining, respectively. Additional <br />information about the Sylvester Gulch ventilation facility can be found in Exhibit 69. <br />No significant groundwater was encountered during slope or shaft excavation at West Elk Mine. <br />However, awater-beazing fault with approximately 5 feet of vertical displacement was <br />encountered at the bottom of the access slope in the B Seam in late 1990. When encountered <br />approximately 100 gpm issued from the mine floor. Dischazge from the fault declined rapidly <br />and the groundwater system was not investigated due to the lack of notable characteristics (i.e., <br />elevated temperature, odor, etc.). Aerial photo studies coupled with subsurface structural data <br />indicate the entry slopes and ventilation shaft aze not located in an area which has significant <br />identifiable fracture zones and, as such, significant inflows have not been induced. <br />The F Seam South Main Intakes were completed in 1982 and consist of five entries. Prior to <br />construction of these entries, and as an effort to enhance MCC's understanding of the area <br />groundwater system, piezometers were installed in the colluviaUlandslide strata immediately <br />upslope of the entries. Based on data from construction of these piezometers, the thickest <br />saturated stratum appeazed along Entry No. 4 (numbered east to west). The colluvium over <br />Entry No. 2 and No. 3 exhibited only a thin saturated thickness which dried up that summer and <br />fall. <br />Entry construction began neaz the end of September 1981. During the period August 20, 1981 to <br />December 12, 1981 some piezometer water levels dropped a maximum of 2 feet above the <br />portals. Water levels in piezometers located downslope showed water level decreases of <br />between 2 and 9 feet during the same period. <br />i <br />2.05-246 Revised June 2005 PRIG; Rev. MarcH 2006; Rev. May 2006 PRIO <br />