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Response: A value was missing from the SEDCAD model for structure 3. A revised <br />SEDCAD model is provided. This correction did not result in any noticeable change to the <br />output. The SEDCAD model contained in Exh. 7-14C document is resubmitted. <br />C. In Appendix Exh. 7-14E, the subwatersheds appear to be poorly delineated. This was also a <br />technical adequacy issue for Technical Revision 97. Please delineate the subwatersheds in a <br />conventional way or explain the rationale for the way they were done in this way. <br />Response: The subwatersheds are based on different Curve Numbers, which in turn are <br />based on the timing when individual areas are backfilled and reclaimed. These polygons <br />match the various backfill polygons presented on Maps 29 and 29A as submitted with this <br />revision. Because the total runoff volume and peak flow are very dependent on an individual <br />subwatershed's curve number, we believe it is only appropriate to separate the subwatersheds <br />by the timing of reclamation. <br />In the SEDCAD model, page 7-14E-26, Subwatershed Hydrology Details table, note how <br />subwatersheds 18-1, 19-2, 15-2, 12-2 and 13-2, (which represent the last areas that will be <br />topsoiled and seeded and have a CN of 80) represent only 23% of the total watershed but <br />produce 55% of the total runoff volume. <br />Also see our response to Comment 18s, which addresses a similar issue. <br />d. In Appendix Exh. 7-14E Streeter is in Sections 2 and 16 also (not just 3, 9, and 10). Please <br />correct this discrepancy. <br />Response: The introductory text in Exhibit 7-14E for Streeter Pond has been updated as <br />requested. <br />e. The intro discussion on different modeling efforts in Exhibit 7 -SP warrants a discussion <br />between Colowyo and DRMS. Some aspects are unclear: for example, why the sub -watersheds for <br />the ditch modeling are different for the pond modeling. The sub -watersheds for the pond model are <br />not as strange as those for the channels, but are still unusual. <br />Response: This topic was discussed in the meeting at the mine with Jim Stark on June 9, <br />2015, and we believe a satisfactory conclusion was agreed to, as summarized below. <br />The sub -watershed polygons in the SEDCAD model and the associated figures are tied to the <br />progress of the backfilling and subsequent reclamation activities that are depicted on Maps 29 <br />and 29A. In some cases there is a substantial time difference in reclamation status and timing <br />for the various sub -watershed polygons, including differences in runoff Curve Numbers (CN) <br />which are tied to the status of reclamation at the point in time that the model represents. The <br />sub -watershed polygons in the ditch and pond models are identical. <br />Therefore, no changes have been made pursuant to this comment. <br />Page 5 <br />