Laserfiche WebLink
West Elk Mlne <br />• In the NW and NE Panels sealed sumps, the floor elevations decrease towazd the northeast, <br />corresponding to the dip of the coal seam. As shown on Figure 28, the resulting storage area (in <br />plan view) matches the panel outline on the north and east with a southwestern boundary <br />perpendicular to the dip of the coal seam (i.e., from northwest to southeast). In the Box Canyon <br />Panels sealed sump, the storage area is defined by the panel outline on the north and the strike of <br />the coal seam on the south. In this portion of the mine, the coal dips nearly due north. All three <br />sumps' southern boundaries are predicated by the elevation of the existing or proposed seals. <br />Because of the dip on the coal seam, the deepest portion of the NW and NE Panels sealed sumps <br />is in the northeast corner, and is in the northwest corner of the Box Canyon Panels sealed sump. <br />In the NW Panels sealed sump this depth is approximately 65 feet below the seal elevation, in the <br />NE Panels sealed sump the depth will be approximately 120 feet below the seal elevation and in <br />the Box Canyon Panel sealed sump the depth could be as much as 270 feet. Details of these <br />large capacity sumps aze as follows: <br />NW Panels Sealed Sumo <br />Mining began in the INW longwall panel in 1992. Operational water used for cooling and dust <br />suppression on the longwall face was allowed to flow down-dip to an operational sump at the <br />northeast corner of the 1NW panel. The water was then pumped to the slope sump and out of the <br />mine to the sedimentation ponds. This practice continued during ruining of longwall panels 2NW <br />and 3NW. <br />• Water management changed slightly while mining the 4NW and 5NW longwall panels. Since all <br />water would not flow via gravity along the dip to the northeast comer of 1NW, water was pumped <br />with air-powered pumps from each of the northeast corners of the 4NW and SNW panels to the <br />north end of the 3NW panel where it would gravity flow to the northeast comer of 1NW and then <br />was pumped out of the mine, as above. In addition, process water from development mining in the <br />Jumbo North Mains and small inflows below Gribble Gulch were pumped into the southwest comer <br />of the 3NW panel at crosscut 29 in the B West Mains while longwall mining the 4NW and SNW <br />panels. Water from this location flowed via gravity through the caved 1NW through 3NW panels, <br />along the dip to the northeast corner of 1NW and then was pumped out ofthe mine, as above. <br />Small, isolated groundwater inflows were encountered during mining of the 1NW through SNW <br />longwall panels. Initial inflows were typically on the order of 5-10 gpm and typically stopped <br />flowing within a few days. Upon completing longwall mining of the SNW panel, removed the <br />pumps and terminated access to the operational sump in this azea by constructing ventilation <br />seals, as required by MCC's MSHA approved Ventilation Plan. Panels 1NW through SNW were <br />completely sealed in May 1995. Therefore, the minor groundwater inflows and the process <br />water from outside this sealed azea that was pumped in through crosscut 29 began to accumulate <br />within the 1NW through SNW panels in May 1995. <br />Ventilation seals were constructed across entries and crosscuts to block gas movement from the <br />previously mined 1NW through SNW longwall panels to the fresh air systems in the B West <br />Mains and active mining sections. These seals aze constructed specifically for ventilation <br />purposes. Atypical seal is comprised of wood block or cribbing approximately 30 inches thick <br />• onto which is blown approximately 4 to 6 inches of expansive foam as a sealant. While this <br />2.05-24/ Revised November 1004 PRIO <br />