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West E[k Mine • percent (0.002) and there is no measurable risk of long-term surface cracks in the internal portions of panels, based on MCC's mining experience to date. Furthermore, the crack connection would need to stay open and clear for long enough to impose a measurable hydrologic change, and this is highly unlikely given the subsurface changes that will be occurring in the aftermath of longwall mining. In a hypothetical situation where a connection were established, the stream channels in question have small drainage basins with average annual surface flows of approximately 200 acre-feet per square mile per year. Cracks will close via "healing" and "sealing," as discussed in response to other questions. These calculations are substantiated by the actual mining experience at West Elk Mine. For example, during the unusually wet late spring and summer of 1995, there were no increased inflows to the longwall panels beneath Gribble Gulch and Lone Pine Gulch. Also, as stated in the October 24, 1994 CDMG Decision Document on the Jumbo Mountain Tract (see page 31), "A direct fracture connection to the mine was not established in Lone Pine Gulch under a cover as low as 120 feet (when F Seam mining was occurring)." Similarly, mining of the B East Mains beneath Sylvester Gulch did not produce a connection with the surface. The groundwater emanating from the B East Mains fault had, and continues to have temperatures in excess of 80°F. This combined with the lack of tritium, 14C and 180 isotopes, (Mayo 1998) indicates this water is not connected to local surface waters. • Additional considerations regazding surface water effects include the following: 1. Mining in the Apache Rocks permit revision area will not measurably impact the surface water hydrologic balance of the Dry Fork of Minnesota Creek. Based strictly on surface acreage, this area contributes only 22 percent of the Dry Fork of Minnesota Creek drainage basin flows as measured above the Lower Dry Fork gage. Because the azea is on asouth-facing slope, however, the actual percentage of surface runoff will be lower. MCC's 1986 Minnesota Creek Augmentation Plan, Case No. 86CW38 (approved by the Colorado Water Court), provides for total replacement of the annual streamflow generated in the Dry Fork basin. For these reasons, impacts to the Dry Fork of Minnesota Creek will be minimal due to B and/or E Seam mining. 2. Mining in the Box Canyon permit azea will not measurably impact the surface water hydrologic balance of the North Fork. As previously stated, 100 percent of the mining area has a B Seam overburden thickness of more than 500 feet, thus all but eliminating the possibility of surface water capture by the mine workings. 3. Based on the B Seam mining plan, in the current permit, which includes the Box Canyon pernut revision area, it is not anticipated that there will be direct mining impacts to Sylvester Gulch. In summary, based on the small amount of surface flow that occurs annually, the low probability of surface cracking due to subsidence, and the depth of cover and the character of the overburden materials within the permit area, the projected mine subsidence will not significantly impact the • streams. 2.05-194 Revised Jvne 2005 PRIO, January 2006, March 2006; Rev. May 2006 PRI G