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West Elk Mine <br />It is feasible to defime which of the springs (and sources) in the permit area are at least 280 feet <br />above the E Seam, which will leave them essentially immune to mine fracture impacts. This <br />analysis has been conducted, and all of the springs in the South of Divide mining area are at <br />least 280 feet above the E Seam. Map 37 depicts these springs. <br />The probable implications to springs caused by subsidence vary between colluvial/alluvial springs <br />and bedrock springs. Colluvial and alluvial springs are much more likely to be impacted by surface <br />cracks than bedrock springs are, while bedrock springs aze much more likely to be impacted by the <br />fractures extending upwazd from the mining azea than alluvial and colluvial springs. These impacts <br />aze discussed in the context of the schematic cross-section provided in Figure 20. Figure 20 depicts <br />the mechanisms via which colluviaUalluvial and bedrock springs can be impacted by longwall <br />mining, as a function of the four different subsidence zones. (1) Caved zone, (2) Fractured zone, (3) <br />Continuous deformation zone, and (4) Zone of surface cracking. <br />These zones aze discussed at length in Section 2.05.6 (6)(e)(i)(C&D) Subsidence Zone Description. <br />The following conservafive interpretation can be applied to the subsidence zones: <br />1. If a spring source is located within the caved zone, the spring may be lost and the source water <br />maybe dischazged into the mine workings. (Deng 1992). <br />2. If a spring source is located within the fracture zone, the spring may either be lost or, <br />particulazly for springs in the upper part of the fracture zone, it may relocate to a lower position. <br />This is supported by Leavitt and Gibbers (1992) who state, "The results for springs are <br />somewhat surprising, as previously held notions suggest that springs aze highly susceptible to <br />longwall mining effects. However, these data indicate that springs are more resilient than dug <br />wells and that more than half of the springs used for domestic water supplies continue to flow, <br />or resumed flow after mining. In a number of locations after a spring ceased to flow, a new <br />spring was reported downslope from the original site. This phenomenon suggests a <br />redistribution of groundwater flow in the neaz surface environment." <br />3. Many colluvial and alluvial springs originate within the uppermost subsidence zone, where <br />surface fractures can occur. In the very unlikely event that a spring source, or the spring itself, <br />happens to be impacted by a surface crack, flow reductions (particulazly on a temporary basis) <br />and/or spring relocation could occur. <br />With these concepts as background, it is feasible to define the probable hydrologic consequences for <br />colluviaValluvial springs and bedrock springs. <br />ColluviaUAlluvial Spring Impacts <br />Roughly two-thirds of the springs in the permit area are colluvial in nature. There is <br />considerable spring monitoring data for West Elk Mine and the majority of the relevant data aze for <br />colluvial springs. As noted above, the relevant data appeaz to demonstrate that F and B Seam <br />mining has not affected the monitored springs. This is not surprising in light of the thick <br />overburden at the mine and the fact that surface cracks aze so infrequently observed. <br />1.05-I68 Revised June 1005 PRlO <br />