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West Elk Mine <br />• sump to raise the water level to reach the elevation of the Lone Pine seals. Within a few weeks <br />(late December 1997), the in-mine pump system at the Lone Pine seals was completed. MCC <br />began full utilization of the sealed sump in January 1998, directing most B Seam mine water to <br />the sealed sump and pumping almost equitable volumes from the sealed sump and from the mine <br />through the Lone Pine Gulch pipeline. <br />1VE Panels Sealed Sumn <br />After the two NE longwall panels have been sealed, MCC will use the sealed area as an additional <br />large capacity sump. This sump will be called the NE Panels sealed sump and will incorporate the <br />existing NE Tailgate sump. Water will be pumped into the NE Panels sealed sump and then to the <br />surface for treatment, if necessary, and discharged to Sylvester Gulch via an approved CDPS <br />discharge point (Outfall #017). <br />Based on the mining layout of the longwa[I panels, the NE Panels sealed sump will have an <br />estimated storage capacity of more than 130 million gallons, or 400 acre-feet. This estimate is <br />based on the volume created by removing a 12-foot thickness of coal by longwall mining plus a 9- <br />foot thick coal section by development mining and applying a 20 percent porosity to account for <br />caving of the immediate overburden. <br />hi February 1998, MCC completed two entries and a horizontal drill hole (NW Sump #1 HDH) <br />within West Elk Mine from the future NE Panels sealed sump azea at the northwest corner of the <br />. 11NE panel, into the NW Panels sealed sump at the northeast comer of 1NW. A significant <br />observation during the drilling of this hole was that there was no water observed in the hole until the <br />drill was within 17 feet of the NW Panels sealed sump. This observation presents compelling <br />evidence of the tightness, or minimal hydraulic conductivity, of the B Seam coal. As described in <br />the following discussion entitled, Sump Operations, these sumps will ultimately be hydraulically <br />connected via the NW Sump #1 horizontal drill hole. Together, the NW and NE Panels sealed <br />sumps will have a storage capacity of neazly 800 acre-feet. <br />Box Canvon Panels Sealed Sump <br />As the Box Canyon longwall panels aze planned to be mined from north to south (i.e, down-dip <br />panels mined first) the mined and caved panels will be used as the NW and NE Panels sealed <br />sumps. Water would naturally flow to or could be pumped into this area for a storage and/or <br />pumped to the surface for treatment, if necessary and discharged. This storage azea will be called <br />the Box Canyon Panels sealed sump. <br />Since the Box Canyon longwall panels are yet to be mined, the specifics about how the water will <br />flow and/or be pumped to and stored in them is not yet know. However, based on the mining layout <br />and projected rnining plan, the available storage volume will progressively increase as mining of <br />panels continues to the south (and up-dip). The estimated storage capacity within the entire Box <br />Canyon longwall panels is in excess of 325 million gallons or more than 1,000 acre-feet. This <br />estimate is based on the volume created by removing a 12-foot thickness of coal in the longwall <br />panels plus the associated development mining. Additionally, a porosity of 20 percent was applied <br />to the volume within the panels to account for caving of the immediate overburden. <br />2.05-283 Revised June 1005 PRl0; Rev. MarcH 1006; Rev. May 2006 PR/0 <br />