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12. There is an error on page 13-12A-1.3 regarding reference to (elevation difference between the <br />calculated top of the sediment storage and the principal spillway invert) being between 0.5 and <br />one (1) as recommended by Warner, et al., 1998. If a slow passive dewatering system is <br />employed (such as is the case with Pond 012) then the elevation can be reduced to 0.5 to 1.0 ft. <br />The second paragraph should be revised to read (elevation difference between the calculated <br />top of the sediment storage and the low-hole spillway/dewatering orifice). Please clarify this <br />discrepancy and revise page 13-12A-1.3. <br />13. In the SEDCAD 4 User's Guide (page 64) it is suggested that a minimum two foot elevation <br />difference exists between the invert of the principal spillway and the top of the sediment <br />storage area. This would apply to Pond 012A since there is no low-hole spillway. The original <br />approved design for 012A (TR-36) had less than the suggested elevation difference (1.49 feet). <br />With TR-37 page 13-12A-1-4.13 (Pond 012 and 012A System) shows a proposed elevation <br />difference between the top of sediment storage and the principal spillway of only.55 feet). A <br />more prudent design and to avoid re-suspension of sediment would be to allow for additional <br />space between the top of sediment storage and the principal spillway elevation. Please <br />reconsider the design for Pond 012A to allow for a minimum two foot elevation difference <br />between the invert of the principal spillway and the top of sediment storage. <br />14. Attachment 13-17 As-Built report for Pond 014 incorrectly references Pond 013 in the <br />Introduction and on page 13-17.1-1. Please correct these pages. <br />15. Culverts that are intended to be permanent as shown on the Post-Mining Topography Map 20-2 <br />should be added to the permanent structures and features discussion in Tab 20 and listed in <br />Attachment 20-1 Permanent Structures and Features. <br />16. In some instances the slope information for the channels provided on Figure 13-12.3 Yoast Post <br />Mining Channel Designs does not match the slope and profile information provided for Post- <br />Mining Channel Profiles Exhibit 20-213. Please check the following profiles on Exhibit 20-213; <br />YPM-6-2(Options 1 and 2), 6-3(Option 2), 6-4, 7, 8, 10, 17, and 20 to ensure that the profile <br />information is consistent with the slope data provided on Figure 13-12.3 and the supporting <br />SEDCAD demonstrations. <br />17. There was no profile provided for YPM-3-2A on Exhibit 20-213. If appropriate please add this <br />channel profile to Exhibit 20-213. <br />18. Revised channel YPM-8 has a nearly 90° turn at the lower end of the channel. This is an abrupt <br />transition and is not a geomorphically stable configuration. The original approved design <br />showed a more gradual bend near the lower end. Please explain why the abrupt bend in the <br />channel configuration has been added to the lower end of the channel or consider revising the <br />channel to a more a stable configuration. <br />19. The Permanent Impoundment Demonstrations Appendix 20-1.2 for Ponds 010, 013, and 014 <br />will need to be amended to include specific information regarding water quality. <br />The water quality discussion provided for each of these ponds is brief and only generally <br />addresses the permanent impoundment requirements of Rules 4.05.9(13) (a). SCC did not <br />adequately demonstrate that water quality in the ponds and discharge from the ponds meet the <br />4