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`J • 2.0 fh•drologir Data lNrrprrtation and Impact Arseumrnr for the Pcnnit and Adjanra Arear 2.5.2 Sanitary Waste Water Sanitary waste water dischazges from the Waste Water Treatment Plant (WWTP) are monitored at discharge point 007. Dis- charge flows to MB-2R where additional detention occurs. Flows averaged 6.42 gpm. There was a maximum discharge during the second quarter of 174 gpm. All monitoring was within effluent limitations. 2.5.3 Mine Water The total WY 1994 mine water inflow from natural mine inflow and water pumped underground was 202.3 acre feet during the yeaz (Table 1.6-1). The total water pumped from the mine and discharged to surface waters was approximately 57.3 acre feet. The quality of mine water is considered good. Mine water was primazily dischazged from the No. 2 Portal. No discharges oc- curred from Sylvester Gulch or Portal No. 5. Because of the small quantity of mine water anticipated, any dischazge from ponds would normally be dominated by water quality characteristics of disturbed area runoff as described in the following section. An anomalous failure of the acute Ceriodaphnia biomonitoring test of MB-2R occurred September 12, 1995. Accelerated testing of effluent yielded passing results over the subsequent three weeks (Table I-2). 2R during the 4th quarter of 1994 when TSS limitations were exceeded (Appendix I). MCC changed their sampling protocol to take samples prior to discharge (each discharge point is gated and discharges are controlled). MB-1 was reconfigured during the second half of 1994 and was lined with a geotextile/clay liner during the 4th quarter. During the construction, mine water was directed to MB-2R. Construction activities included the material storage bench and auxiliary facilities in Lone Pine Gulch. MB-4 did not discharge during the WY and records indicate it has not dischazged since it was constructed. MB-4 sometimes catches hydraulic oil washdown from the Unit Train Loadout. When this occurs, sorbent materi- als aze placed in the pond to capture the oil product or the pond is pumped by a licensed contract hauler or the MCC vacuum truck. The pumped oil and water is deposited in the shop oil/water separator, the "clean" water is then discharged to MB-2R and the oil is collected in the used oil tank. There were several spills resulting in the removal of approximately 1,200 gallons of oily water. Mountain Coal initiated an Incidence Reporting process in October 1994, which should result in more detailed future reponing. 2.5.4 Runoff from Disturbed Area Mine site runoff is treated by ponds MB-1, MB-2R, MB-3, MB-4 and MB-5. Effluent limitations were met at all sites except MB- AEat-95.2t0/05/IS/96(1:78pm) 22 REVLSED IO/08!96