2011-02-15_REVISION - C1980004 (2)

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Corey Heaps McClane Canyon Mining, LLC February 15, 2011 Page 20 • The Division requests that a larger plan view of the sediment pond be provided. The plan view of the sediment pond provided in Figure 2.2 -3 is too small to see details. • The Division requests that Figure 2.2 -3 be revised so that more of the subwatershed .drainage basins are shown. • On revised page 2.05 -21, the use of a centrifugal pump is mentioned as an optional way of dewatering the sediment pond. The Division requests that mention of this option be added to Section A -A' of Figure 2.2 -3. 101. The Structure Networking sheets on pages 20 and 21 of Appendix M show that culvert C -13 flows directly into the sediment pond and that culvert C -18 flows directly into ditch D -18. However, on Figure 2.2 -3, the culvert leading directly to the pond appears to be labeled as culvert C -18 and culvert C -8 leads into ditch D -18. Please explain. 102. Several of the ditch designs show water velocities above 5.0 feet per second but not all of the ditches are designed to be riprapped, including ditches D -3, D -5, D -11, D -30 and R -1. Please explain. 103. Please add a discussion to the permit text, or point out where such a discussion is located in the permit, concerning inlet and outlet protection for culvert C 11. 104. Because culvert C 11 will be about 600 feet long, does MCM intend to construct access sites in case the culvert gets blocked or construct inlet protection to minimize debris entering the culvert? Please add a discussion to the permit text concerning this issue. 105. On page 1 of Appendix N - Probable Hydrologic Consequences, Figure 4.2 -3 is referenced as showing the projected saturated zone of the Cameo Coal Seam. Please update Figure 4.2 -3 to reflect the projected saturated zone given the mine expansion and new permit boundary proposed with PR -2. 106. On page 2 of Appendix N there appears to be an error in describing the groundwater flow direction. In the second and third sentences of the second paragraph, MCM states that the flow through the coal seam is from the northwest to the northeast. From Figure 4.2 -3 It appears that the flow direction would be more correctly described as being from the southwest to the northeast. Please check this information and make the appropriate corrections. 107. Well GW -3 is used as the groundwater monitoring point for the gob leachate analysis presented in Appendix N. As stated previously in Items 12 and 89 above, the Division believes that a new well closer to the refuse pile location would be more appropriate for identifying potential impacts from the gob leachate. We believe that the PHC analysis for GW -3 with regard to conductivity increases remains valid. However, monitoring results from a well closer to the refuse pile would validate the conclusions presented for both conductivity and metals concentration increases in groundwater and surface water.