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11. Diversion of runoff off of the face of the fill resulting from the 100-year, 24-hour storm <br />event is required pursuant to Rule 4.09.2(7). Colowyo has proposed two ditches to <br />accomplish this for the East Taylor Fill. These two ditches are the East Taylor West <br />Tributary Ditch and the East Taylor East Tributary Ditch. These ditches, however, do not <br />extend the entire length of the East Taylor Fill and, therefore, do not convey all of the runoff <br />off of or around the fill. Pursuant to Rule 4.09.2(7), please lengthen the East Taylor <br />West Tributary Ditch and the East Taylor East Tributary Ditch to the beginning point <br />(south) of the East Taylor Fill so they adequately divert water off of and around the <br />East Taylor Fill. <br />Response: As part of the redesign of the permanent tributary ditches required to conform <br />to the revised post-mining topography associated with this submittal, all four primary <br />permanent ditches (East Taylor East, East Taylor West, West Taylor East and West Taylor <br />West Tributary Ditches) have been extended to near the upstream end of each ditch's <br />tributary area. Please refer to revised Exhibit 7, Item 20, Part E and revised Maps 33B <br />and 41 A. <br />12. As shown on Map 41A - Watershed Boundaries for Hydrological Modeling and Map <br />45 - South Taylor Fill, Colowyo proposes the use of terrace ditches both in the backfill <br />above the West Taylor Fill and on both the East and West Taylor Fills to divert runoff off of <br />and around the fills. Pursuant to Rule 4.09.2(7) these ditches must be properly sized and <br />constructed to carry the runoff from a 100-year, 24-hour storm event. Colowyo does <br />provide general design information for the terrace ditches in Exhibit 7, Item 20, Part G (in <br />Volume 13). The introductory text of the exhibit states that "(a) series of terrace ditches will <br />be constructed across the face of the permanent fills..." Based on the above referenced <br />maps, Colowyo is also proposing additional terrace ditches above and on the West Taylor <br />Fill that must be sized for the 100-year, 24-hour storm event as well. Please amend the <br />text in Exhibit 7, Item 20, Part G to include a discussion of the terrace ditches that <br />will be constructed in the backfill above the West Taylor Fill and a discussion of the <br />terrace ditches that are located on the middle portion of the West Taylor Fill that flow <br />into the West Taylor West Tributary Ditch (from approximately station 25+00 to <br />approximately station 40+00, three ditches). <br />Response: The terrace ditches were all re-designed to conform to the revided post- <br />mining topography associated with this submittal. All terrace ditches, including those on the <br />valley fills as well as those in the pit backfill areas above the valley fills have been sized to <br />handle the 100-year, 24-hour storm. Please refer to revised Exhibit 7, Item 20, Part G, and <br />revised Map 41A. <br />Rule 4.05.6 - Sediment Ponds <br />13. The footer for the West Taylor Pond SEDCAD modeling states that the revision is <br />TR-82. The correct revision number is TR-81. Please change the footer information for <br />the West Taylor Pond SEDCAD modeling to TR-81 to reflect the correct revision <br />number.