2008-06-16_REVISION - C1994082 - Laserfiche WebLink

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6. Hydrologic input parameters including original approved curve numbers (Table 13-1) for Ponds 010 and 011 were initially given in Tab 13 Facilities section. Attachment 13-12 was subsequently prepared for the Yoast South area (Ponds 012, 013, and 014) and contained a second modified curve number table. With TR-37 Attachment 13-12 was significantly modified and Table 13-12.1 Yoast Mine Curve Numbers was substantially expanded. We now have two lengthy curve number tables in two different sections of the permit. To avoid confusion, it would be helpful to have both curve number tables be consistent with each other, or refer the reader to just one location in the permit for approved curve numbers. Please update the appropriate sections of the permit document accordingly. 7. A couple of errors were noted on Figure 13-12.3. Channel YPM-6-2A was not included in the figure. Under YPM-18 the slope is given as 11-313%. Please make the necessary corrections to Figure 13-12.3. 8. On new Exhibit 13-12.1A and revised Exhibit 20-2, Postmine Channel YPM-3-2A is missing. Please include this channel on the exhibit. 9. The watershed boundary designations have become confusing and difficult to correlate between the channel and pond designs and the exhibits that show the watershed boundaries and designations. For example, it appears that the designations shown on Exhibit 13-12.1 no longer correlate with the Watershed Identifications and the hydrologic input parameters for the postmine channel and pond design SEDCAD runs for the Yoast South area. It is also appears that Exhibit 13-413 needs to be updated with the current watershed condition as of September 2007 and with new Channel YPM-22. If appropriate, remove Exhibits 13-12.1 and 13-413 and replace them with a single map showing the revised watershed designations. Alternatively, the appropriate watershed designations could be added to the new Exhibit 13-12.1A. 10. Please revise Appendix 13-12.3 with an updated channel design(s) for the YPM-4, 4-1, 4-2, YPM-17 and Diversion 13A system of channels that flow into Pond 013. There were no previous existing designs for Diversion 13A and it appears that the existing channel information to be retained for YPM-4, 4-1, and YPM-17 do not match the new Pond 013 As- Built SEDCAD design information for contributing areas and peak discharges. 11. Since the recent slide activity at Pond 012, the configuration of the pond has obviously changed. This was confirmed by the pond storage capacity survey submitted May 28, 2008 for Abatement Step 1 of NOV CV -2008-001. In the new certified As-Built Report for Pond 012 (Option 1) page 13-12A-1.4, SCC indicates that "Exhibit 13-6, As-Built Pond 012, presents the existing impoundments configuration and structure elevations". This statement is no longer correct since the slide occurred after the submittal of TR-37 and the configurations and structure elevations have changed. Please remove the revised Attachment 13-12A As-Built Report from the revision application since this report is no longer appropriate. As stated above in Item 5, we recommend the two-pond option (012 and 012A in series) that should be designed in concert with the slide remediation plan and takes into consideration a smaller dimension for Pond 012. Please resubmit a new design for the two-pond system accordingly. New certified As-Built Report and new As-Built Map for the two pond option (012 and 012A design) will be required following construction.