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10 <br /> <br /> <br />Thickener water transferred underground for storage was estimated at 2,760,000 gallons <br />during the reporting period. This number is based on operational knowledge of the tons <br />washed and other factors such as the type of clays encountered, processing equipment <br />efficiencies, etc. <br /> <br />The incidental category includes leakage from water lines, dust control watering in the <br />haulage entries, and washdown water used in the slope and other locations. It is <br />assumed that 10% of the water used for production equipment will fall under this <br />category. <br /> <br />Outgoing Water As coal is mined, water is added by dust control sprays on the <br />continuous miners, the longwall shearer and at transfer points along the conveyor belt <br />system. This water is then carried out of the mine as surface moisture on the raw coal. <br />This added coal surface moisture represents a 4% increase in the raw coal moisture <br />content. The raw coal tonnage produced during this reporting period was 2,288,958 tons. <br /> <br />Water leaving the mine as ventilation humidity represents a large quantity in the water <br />balance. The temperature of the exhaust ventilation air is almost constant, at 60o F. <br /> <br />Up until the commissioning of the new mine dewatering system in May 2012, no <br />underground water had been pumped out since January 1996. Water encountered in the <br />active areas of the mine was pumped to the mined out D seam area for storage. <br /> <br />In May 2012 a new dewatering system was commissioned to pump excess mine water to <br />the surface for treatment, storage, and potentially discharge. An average of 35.50 gpm <br />was pumped to the surface. No discharge of the dewatering waters through the <br />associated NPDES outfall occurred during the water year as most of the water was <br />allowed in infiltrate through multiple ponds. <br /> <br />Pumping resumed from the D-Seam through SDH-3 on July 1, 2015. This water is <br />discharged through Outfall #026 following treatment involving aeration and settling. No <br />water was pumped to the surface from the D-Seam during this water year but will resume <br />early next water year. <br /> <br />2.2.1.6 NPDES Discharges At present, BME has 12 NPDES outfalls. Only Outfalls <br />001 and 029 discharged during the 2016-17 water year. 029 discharge was as a result of <br />pumping out of the B-Seam. Laboratory results and DRMs for Outfalls 001 and 029 are <br />provided in Appendix F. <br />