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Mountain Coal Company 1998 Aouual Hydrology Report West E!k Mine u Tahle 9 Sedimentation Ponds Numeric Discharge Limits Sedimentation Ponds Parameter and Time Period Discharge Limit Total suspended solids (mg/L) • 30-day average 35 • 7-day average N/A • Maximum 70 Total dissolved solids (mg/L) • 30-day average N/A • 7-day average N/A • Maximum Report Oil and grease • 30-day average No sheen • 7-day average No sheen • Maximum No sheen Total iron (mg/L) • 30-day average 3.5 • 7-day average N/A • Maximum 7~0 pH (standard units) • 30-day average 6.5-9.0 • 7-day average 6.5-9.0 • Maximum 6.5-9.0 • No visual sheen should be present. If sheen is present, total concentration cannot exceed 10 mg/L. Mine Waterlntlows Mine inflows continued as described in the ] 997 AHR. Flow continued from the B East Mains (BEM) fault and the 14 Southeast Headgate (14SEHG) fault, although flows from both faults diminished and relocated as mining progressed downdip along the faults. MCC also experienced the usual small inflows, which quickly subsided, as development mining occurred. BEM Fault Inflow U The flow from the BEM fault inflow continued during WY98, but as the downdip expressions of the fault were mined through, the updip flow ceased and relocated to the downdip location. The flow moved from the B East Mains to the 14 Southeast Tailgate (14SETG) at 3 cross-cut in December 1997. The flow rate at this new location was approximately 250 gpm. In February 1998, the flow dried up in this location and began flowing in the 23 Headgate (23HG) at 6.5 cross-cut, where it remained through the end of WY98. The initial flow was approximately 200 gpm and is now currently flowing at 65 to 100 gpm. The flow is in the 23HG sump, so a sample at the source is not feasible. All locations aze shown on Map 1. 831- 3.00 age20 Wrig iWaterEngineers