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19. As was done for the curve number of 91 on the second page of the Pond Design Memo in <br />Appendix 2.05.3(3)-1, please justify the use of the curve number of 79 for the subwatersheds <br />for culverts C-6 and C-6A. <br />Response - The use of a curve number of 79 is justified for the subwatershed areas SW- <br />MD and SW-MD2 as these areas consist of pasture or rangeland with fair hydrologic <br />conditions and hydrologic soil group C as shown in the SedCAD software and are not <br />part of the mine's disturbance area. <br />20. Please designate the extent of the riprapped section of ditch NHN-002 South Riprap on Map <br />2.05.3(3)-1. <br />Response - Map 2.05.3(3)-1 has been revised to show that the entire ditch will be rip- <br />rapped <br />21. Please explain how all of the runoff from a subwatershed, such as SW3-A, can get to the exit <br />culvert of the subwatershed, such as culvert C-7, without downgradient cross ditches that <br />would bring the runoff to the culvert. <br />Response -All ditches will be constructed to provide positive flow towards respective <br />ponds. <br />22. Please explain how the upgradient runoff will be diverted around the disturbed area <br />perimeter collection ditches. <br />Response - Upgradient runoff is diverted by County roads surrounding the permit area. <br />23. On page 22 of Section 2.04.7, it is stated that sediment pond NHN-001 is designed to <br />receive pumped pit water and backfill seepage water. Please point out where pumped pit <br />water and backfill seepage water are accounted for in the hydrology designs for pond NHN- <br />001. <br />Response - NHN-001 is appropriately sized to accommodate pit pumpage. See Page of <br />ARCADIS report. <br />24. It does not appear that subwatershed SW-3C is shown on Map 2.05.3(3)-1. Please revise <br />Map 2.05.3(3)-1 accordingly. <br />Response - Map 2.05.3(3)-1 does show subwatershed SW-3C. <br />25. On Map 2.05.3(3)-1, the subwatershed for the topsoil stockpile area is mislabeled as SWl- <br />A. Please revise Map 2.05.3(3)-1 so that the label reads SW-TS. <br />Response - Map 2.05.3(3)-1 has been revised to show correct labels. <br />26. Referring to Map 2.05.3(3)-1, it appears that haul road embankments are immediately <br />adjacent to all three sediment ponds. Please discuss whether or not the standing water in the <br />sediment pond might come into contact with the toe of the road embankment and, therefore, <br />affect the geotechnical stability of the road embankment. <br />Response - Map 2.05.3-1 has been revised to show revised haul road configuration to <br />avoid the issue raised in the comment. <br />Response to First Adequacy Review Page 36