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9. Mine Drainage Treatment System <br />Water drains from the mine through a pipe in one bore of the <br />adit /rock tunnel. The mine drainage water is treated to ensure <br />water quality standards are met when the water discharges into <br />surface receiving streams. Water treatment is done by mechanical <br />means, settling and flocculation, as follows. <br />Underground Sizing Screen <br />Chapter IV <br />The mine drainage is routed through a sizing screen which is <br />located underground, in the tunnel. The function of the screen is <br />to remove coarse solids from the water, which then continues to <br />drain through the pipe and out the tunnel. <br />Mine Water Treatment Plant <br />The mine water flows through a valve box which is situated in the <br />tunnel portal yard area, near the lamphouse. Flows are routed at <br />the valve box between the ditch leading to the 016 pond(s), and the <br />pipeline leading to the water treatment plant which is located in <br />the coal preparation plant structure. <br />The pipeline extends from the portal yard valve box down to the <br />preparation plant. Water is conveyed through the pipe into the <br />plant to the recycle sump /hydroclone of the mine water treatment <br />plant. <br />The function of the recycle sump /hydroclone is to separate middling <br />solids from the flow. The solids, contained in the underflow, <br />report to the coal preparation plant, or to the 001 sediment ponds. <br />Overflow from the recycle sump /hydroclone proceeds to the mixing <br />tank for flocculation, and then flows out of the plant, through a <br />pipeline to the 020 pond for "finishing" prior to discharge into <br />Coal Creek. In the alternative, some or all of the overflow may be <br />routed to the 001 ponds for "finishing." <br />Settling Ponds <br />As an alternative to, or in combination with the water treatment <br />plant, flows are routed at the valve box to the 016 pond series for <br />settling of solids prior to discharge to Dutch Creek. <br />A total of eight ponds, at three outfalls, can be utilized for <br />settling of solids from the mine drainage water. These include the <br />three pond series at Outfall 016, known as the "tunnel ponds "; the <br />pond at Outfall 020, known as the "picnic pond "; and the four pond <br />25(a) <br />