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Technical Revision No. 80 ............................................................................................................ Page 5 September 22, 1997 if necessary, and discharged. As described in the TR application and as discussed in response #2 above, pumping of the B East Mains inflow water to the NW Panels sealed sump began in November 1996, on an emergency basis because the sedimentation ponds were full and frozen-over, and could not be effectively treated to allow discharge within effluent limitations due to the TSS problem. MCC had received a letter from the Colorado Water Quality Control Division (CWQCD) that no additional NPDES exceedances would be acceptable. 6. MCC disagrees that the statements referenced are discrepancies. MCC has not yet completed studies into the origin of the fault waters, but expects completion and submittal to the Division within the next few months. As such the text discusses possible, theoretical sources based on limited data. The source of the B seam inflows described in the second bullet on page 2.05-219 refers to both large inflow events that have occurred in the West Elk Mine - the B East Mains and the 1 SE Headgate inflows. 7. The update to Figure 24, "Estimated Annual Total Ground Water Inflow to Mine", was inadvertently missed. In 1994, the volume was 8.7 acre-feet (AF) or 5.4 gallons per minute (gpm). In 1995, the volume was 2.0 AF or 1.2 gpm. In 1996, the volume was 321 AF or 199 gpm. The figure will be updated to include this information. 8. Discussions of how MCC plans to handle large future inflows is already included in many places in the permit text. These discussions include the NW Panels sealed sump, the NE Panels sealed sump, the Box Canyon Panels sealed sump, the Lone Pine Gulch pipeline system, and the 2,000 gpm mine pumping and water treatment system in Sylvester Gulch. In addition, MCC in the past has demonstrated the ability to handle large inflows (up to 8,000 gpm) with its existing mine pipelines and sedimentation ponds. MCC acknowledges that the two large inflow events were surprises and the existing sedimentation pond treatment system was limited in effectiveness. Therefore, MCC evaluated and provided the above-described mine water management system which takes into consideration the possibility of encountering future large inflows. An inte rat, I component of this system is MCC's current and future use of the sealed panels sumps. 9. MCC was only recently able to take a water sample from within the lower-most 7NW panel seal at Lone Pine Gulch (as water had reached the seal) and had it analyzed by an independent water quality laboratory. The sample indicated that the NW Panels sealed sump water would meet NPDES effluent limitations. The results are roughly comparable to groundwater quality in the area, based on numerous samples analyzed by MCC over the past approximately 15 years, as presented in the Annual Hydrology Reports. MCC plans to continue to take samples at this seal in preparation for discharging mine water through the Lone Pine Gulch pipeline. Although there are differences in the quality of the sump water and the fault inflow and background B-seam well waters; the sump water is generally of good quality, and