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Mr. Mike Boulay Divir:on ofMineralr and Geology Page 2 4. The contour interval asgwen in the Legend it incorrectly mated ar S ft. instead of 25 ft. Pkare cared this on Exhibit 20-2. Response: Ouz review of the Legend shows that it correctly identifies the contour interval as 25 ft. Eor the Postmining Contours and 5 ft. for the base (undisturbed) areas. If the Legend still continues to cause confusion, please suggest an alternative for clarification. S. Exhibit 20-2A mar changed rign~cantly with this revision by removing most of the pre-mining topography configuration fivm the crorr- rectionr. The only pre-mining topography now shown on the exhibit it in the arias that men undisturbed The primary purpose of the pre-mining drporbmining rears-sections it to chow how well the ftnalgraded doper approxrnrahgre-mining doper. Pkare add the pn- mining topography lines for dirturhed areas back onto Exhibit 20-2A for each cross-section. Response: Pre-mining topography has been added to the exhibit. 6. Existing approved SEDCAD demonstration wen retained for channels YPM-8 through 13 and YPM-16. Mort of the associated channel profiler for there demonstrations aLco remained the same, However, the channel profiler men nvired on Exhibit 20-2B for channels 1'PM-8 and 1'PM-16, but no new SEDCf1D demonrtrationr wen submitted The existing SEDCAD demanrtrotionr for channels 8 and 16 do not appear to correlate well with the new revised channel profiler. Please clarify ihir discrepancy and if necessary submit new SEDCAD demonstrations for channek 8 and 16. Response: We believe that when the approved profiles Eor channels YPM-8 and YPM-16 (PR-02) aze overlaid by the channel profiles submitted for TR-29, there are very minor differences in the profiles. The primary differences that we can find aze minor differences in the percent of grade shown on the profiles. This is solely an artifact where the grade break is selected; when the postmine crontouts are compared between PR-02 and TR-29 they are very close to the same (diffenntAilT'OC/iD technicians developed PA-02 and TA-29). Therefore, we believe the SEDCAD demonstrations remain valid. Neither of the Stork Pond Proposed Deagnr (ST-1 and ST-2) meets the nquiretnentr of 4.OA9(7)(d). Bared on the SEDC-AD demonstratioru and the Stock Pond Stage Capacity infomationgiven on the plan view drawings, neither mock pond design shomr the minimum 1 foot elevation of the top of the embankment above the water surface in the pond with the emergency spillway flowing at design depth. It would afro be helpful to chow the ride rkpe inforreation for the embankments on rice design drawings to demonstrate compliance with 4.05.9(7)(e). Pkare revue the Stock Pond ST-1 and ST-2 Proposed Derigrn (Figuresl3-12S and 13-12.6 to chow the correct depth offbwforST-2 Emergency Spilhvay. Response: Review of other Stock Pond design drawings at other Seneca operations, the minimum 1-foot freeboard is not indicated on the design drawings; however, it is called out on Figure 13-12.5, Yoast Mine Posttnining Emergency Spillway Designs, page 8 of Attachtnent 13-12, and is also documented in the SEDCAD demonstrations. 8. Please revise the Stock Pond Spillway Summary Table presented on page 8 of the revised Attachment >3-12 and Figure 13-12.5 to sham the tarred depth of flow for ST-2 Emergency Spillway. Response: Figure 13-12.5-2, Yoast Mine Postmining Emergency Spillway Designs, and page 8 of Attachment 13-12 have been revised. 9. A SEDCAD demonstrtation shaming the rr~brnb requirements fortbe spillway channelrforST-1 and ST-2 men natincluded in Appendix 13-1 Z.S. Please provide an emergency pillway channel design for each stock pond for inclusion in Appendix 13-125. Response: SEDCAD demonstrations showing the riprap requirements for the spillway channels fox ST-1 and ST-2 aze attached.