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Kathy Welt, MCC <br />July 20, 1998 <br />' Page 2 <br />northeast corner of 1 N W and then was pumped out of the mine, as above. <br />' • Small, isolated groundwater inflows were encountered during mining of the first five <br />longwall panels. Initial inflows were typically on the order of 5-]0 gallons per minute <br />' (gpm) and typically stopped flowing within a few days. <br />• Upon completing longwall mining of the SNW panel, MCC removed the pumps and <br />terminated access to the operational sump in this azea by constructing ventilation seals, as <br />required by MCC's MSHA approved "Ventilation Plan". Panels 1NW through SNW <br />were completely sealed in May 1995. Therefore, the minor groundwater inflows and the <br />' process water from outside this sealed area that was pumped in through crosscut 29 began <br />to accumulate in May 1995. <br />• MCC sub-leased the B-Seam coal north of the NW Panels to Bear Coal Company in the <br />1980s. As part of the agreement, MCC had the right to and did inspect the Bear Mine <br />workings and receive copies of current mine maps. In 1993 and 1994, Mark Scanlon, <br />MCC's geologist during this period, observed fractures in the Bear Mine containing <br />water and received reports of additional fractures encountered that contained water. <br />' • MCC personnel went into the Beaz Mine some time in 1994 to determine whether Bear <br />was having similar problems mining beneath the Lone Pine Gulch drainage as MCC. <br />They were unable to proceed into the third west, third north panel as the area had been <br />' sealed, reportedly (per Dan Beaz) due to poor roof conditions and water. MCC staff also <br />observed a water pump lying just outside a sealed area. <br />' • MCC encountered poor roof conditions and initial inflows of 50 gpm while mining the <br />bleeder entries at the north ends of panels 6NW and 7NW. These inflows diminished to <br />nearly zero over a few weeks. These locations are beneath Lone Pine Gulch and have an <br />' overburden thickness of 300 to 400 feet. MCC had to implement several measures to <br />stabilize the roof in this area and needed to reestablish the longwall setup rooms in panels <br />6NW and 7NW. Longwall mining of panels 6NW and 7NW was completed and the <br />' panels were sealed in July 1996 <br />• In March 1996, the continuous miner encountered a fault in the B East Mains. Initial <br />' inflows from the B East Mains fault were estimated at 2,500 gpm with flows eventually <br />leveling out at approximately 80 gpm. The unprecedented inflows coupled with the <br />presence of colloidal clay particles created treatment difficulties for TSS in the <br />' sedimentation ponds. Surface applications of alum provided the most effective treatment <br />and allowed MCC to meet their dischazge permit limits with only a couple of exceptions. <br />• In November 1996, two key events occun•ed that forced MCC to alter their water <br />management and treatment practices. The first was a letter from the CWQCD stating that <br />if MCC had additional permit exceedances, then enforcement actions, including fines, <br />' would be assessed. The second was that the sedimentation ponds were freezing over, <br />thus rendering alum applications infeasible. These two events led to the decision to <br />pump the "dirty" water to the mined NW panels, creating the NW Panels sealed sump. <br />1 <br />