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Mountain Coa/ Company 1998 Aoeual Hydrology Report West E!k Mrne <br />14SEHG Fault Inflow <br />• During WY98, the 14SEHG inflow continued for most of the yeaz in the headgate where the <br />inflow was first encountered. The flow remained fairly constant at around 200 gpm. Then as <br />was observed with the BEM fault inflow, as the downdip expression of the 14SEHG fault was <br />mined through, the flow dried up and relocated to the downdip location. In July 1998, the flow <br />moved from the headgate to the tailgate of the ]4`~ panel at 16.5 cross-cut. The initial flow was <br />250 gpm and at the end of WY98 was approximately 130 gpm. These locations are identified on <br />Map 1. <br />Minor Inflows <br />As is typical, MCC encountered small inflows during development mining with continuous <br />miners. Initial inflows ranged from less than 0.05 gpm to 15 gpm, and then decreased to drips, <br />or dried entirely. The exception to this is the inflow located in the ]ONETG. This inflow was <br />reported in the 1997 AHR, and continued to flow during WY98 at approximately 50 gpm. The <br />majority of the small inflows came from the roof. The locations of the inflows are shown on <br />Map 1. <br />NW Panels Sealed Sump <br />During WY98, MCC continued to utilize the NW Panels sealed sump, which is the area that was <br />created by mining the 1NW through 7NW longwall panels, and shown on Map 1. The use of this <br />• sump allowed MCC to become more efficient in handling mine inflows so as not to overload <br />sedimentation ponds MB-1 and MB-2R, and to ensure that water is dischazged in compliance <br />with MCC's CDPS dischazge permit. MCC routed most of the mine inflow water to the NW <br />Panels sealed sump. <br />MCC received approval from the Colorado Department of Public Health and the Environment, <br />Water Quality Control Division, to discharge mine water through discharge point #013, also <br />known as the Lone Pine pipeline. The surface portion of the Lone Pine pipeline had been <br />completed during WY97, and the underground portion of the system had been completed in late <br />1997, which included relocating the seals to allow water to have sufficient head to be pumped. <br />When the water in the NW Panels sealed sump filled to the elevation of the new seals, MCC <br />began pumping water out of the sump through the Lone Pine pipeline, which began in late <br />December and early January 1998. MCC had originally planned to construct mine water <br />treatment ponds at the outlet of the Lone Pine pipeline to treat the water, but delayed the project <br />as initial water quality samples out of the Lone Pine sump (prior to pumping) indicated that the <br />water would meet all CDPS standards. As pumping began, and continued throughout WY98, the <br />quality of the water from the Lone Pine pipeline has been good. A biomonitoring sample taken <br />for the 3rd quarter 1998 did fail, but accelerated testing was successful, and, therefore, not <br />considered a failure. <br />The NW Panels sealed sump was assumed to be full (about 375 acre-feet) during WY98, as <br />MCC pumped water into the NW Panels sealed sump at about the same rate as water was <br />pumped out of the sump. <br /> <br />831-032.5 0 Page 1 rig t Water ngineers <br />