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West Elk Mine ~~ WWE has reviewed the cited TDS computations. The methodology is reasonable and provides a conservative projection of what could occur in the azea. This analysis can be translated to the Apache Rocks and Box Canyon permit revision areas. As discussed in Surface Water Quality Effects, WWE has revisited the TDS loading analysis conducted by CDMG and found that, even under the extreme conditions of 1996 and eazly 1997 when MCC was forced to dischazge lazge quantities of mine water without adequate treatment (in response to large inflows from the B East Mains and 14SE Headgate fault inflows), TDS levels in the North Fork were well below those considered to be a concern. 10. "Mine inflows aze not normally significant when ephemeral streams are undermined and most of the streams to be undermined in the region aze ephemeral. Flow in these ephemeral streams occurs in periods of snowmelt and high intensity precipitation events. The stream gradients are steep and their channels contain little alluvium," (p. 28). In both the current permit and Box Canyon permit revision areas, all of the streams are ephemeral, except a portion of the Deep Creek channel in the southeast quaztei of Section 26. Their steepness is chazacterized in Exhibit 55, which contrasts pre- and post-mining~sediment transport. As described in the section Groundwater Quantity Effects, the B East Main fault inflows aze not directly linked to surface inflows. This is also believed to be true of the inflows from the 14SE Headgate fault. ~~ The experience of other mines in the azea is useful in assessing possible ground water conditions in the B and E-Seam. The Beaz Mine No. 3 C-Seam workings are particulazly relevant (see Map 5). During previous inspections of this mine, no noticeable flowing azeas within the mine were observed. Mine operators reported inflows of less than 20 gpm in 1995 to the Beaz No. 3 B-Seam workings (see section entitled Groundwater Quantity Effects). ;Similar to the Mountain Coal Company F-Seam experience, occasional roof drippers have been observed. Seasonal inflows in the portal areas have been observed, similaz to Mountain Coal Company's experience in the F- Seam. Water has been observed in a pressurized state dischazging from fractures just below landslide debris in the portal of the Beaz mine in 1986 during a period of high rainfall in the spring season. The Oliver Mine, on the east side of Sylvester Gulch reportedly encountered relatively high ground water inflow as Sylvester Gulch was approached in 1954. There is no evidence of flow out of the adit at the present time. This is consistent with Mountain Coal Company's experience in the F- Seam asSylvester Gulch was approached and overburden thinned. Somerset Mine (formerly U.S. Steel) mining operations north of the North Fork encountered higher inflows when mining approached a level at or below the level of the North Fork. It is expected that similar conditions will exist within a small azea of Mountain Coal Company's property below the level of the North Fork. I. Probable Hydrologic Consequences - 2.05.6 (3)(b)(iii & viii) 2.05-l47 November 2004 PR/I