2022-09-29_PERMIT FILE - C1980007 (2)

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West Elk Mine • In the first case, the spring source will either be lost to the mine workings (where it will be collected, treated, and eventually dischazged, as appropriate) or the spring will relocate. Relocation is more likely in the upper portion of the fractured zone, as discussed previously in Section 2.05.6. Map 37 shows all spring locations within the permit area. B and E Seam overburden information is provided on Map 14 and Map 19, respectively. A review of these maps show that there are no springs with less than 270 feet of overburden cover in the South of Divide mining azea In the second situation (spring and/or spring source within 100 feet of ground surface), the spring flow will not be lost to the mine workings unless the bedrock source is within 270 vertical feet of the B or E Seam mine workings and within the subsidence angle of draw (i.e., 10 to 20 degrees). Assuming there is a separation distance of greater than 270 feet, the water-bearing bedrock unit could be disrupted only by surface or tension cracks which develop over the chain or barrier pillazs, thus potentially diverting the groundwater into deeper permeable units. The effect of such an event would likely be to permanently displace the spring to adown-gradient location where a deeper permeable unit is exposed to the surface. Alternatively, the surface crack will, with time, become saturated or will "heaUseal" itself and the temporarily disrupted spring will again flow. The key point to recognize regazding surface cracks is that their occurrence is infrequent. In both cases described above, the groundwater diverted as a consequence of mining will not be lost from the drainage system. In the first case, the groundwater will be collected in the mine workings, pumped to the surface, treated, and eventually discharged to the North Fork or Dry Fork in compliance with the existing NPDES permit. In the second case, the groundwater may be permanently relocated to adown-gradient location or temporarily stored in asubsidence-induced surface crack. None-the-less, the groundwater will remain as part of the historic drainage. Spring flow observations in the general vicinity of the BEM and 14HG Faults have not shown unchazacteristic changes as a result of the mine inflows. Underground Water Storage As a result of the unprecedented inflows of groundwater into the mine from the BEM and 14HG Faults (see previous discussion under Mine Inflows), MCC began using the space provided by the previous mining of longwall panels 1NW through 7NW for temporary storage. As more information was obtained relative to the volume and chazacteristics of this groundwater inflow, a decision was made to continue the use of this storage azea or sump. In fact, this use of storage resulting from previous longwall mining is to be utilized in other portions of the mine (i.e., the NE and Box Canyon Longwall Panels). This section of the permit text is provided to describe the Bumping of water within West Elk Mine and to discuss the associated PHC's. It is important to differentiate between the depressions in open entries (or operational sumps) constructed within most mines to collect the day-to-day groundwater inflows and operational runoff water (usually of small volume) and the serendipitous use of storage created by the previous mining of coal in strategically located down-dip portions of the mine (or sealed panels sumps). These local collection azeas aze herein refen•ed to as "small capacity sumps" and "lazge capacity sumps," respectively. 1.05-277 Revised June 1005 PRlO; Rev. Masch 2006; Rev. May 1006 PRIO