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COMMENTS/RESPONSES FOR TR-71 <br />1. Rule 4.05.9(2) requires the applicant demonstrate that the 25-year, 24-hour storm event <br />can be safely passed through the emergency spillway of an impoundment (sediment <br />pond). No SEDCAD design information was provided for this larger storm event. <br />Please provide the necessary information to comply with Rule 4.05.9(2) for the <br />Section 16 pond. <br />Response: In accordance with Rule 4.05.9(2), all information pertinent in demonstrating <br />that the 25-year, 24-hour storm event can be safely passed through the <br />emergency spillway or an impoundment (sediment pond) is included with this <br />submittal in Exh. 7-140-17. All pages of Exhibit 7-140-4 have also been <br />resubmitted with this package. <br />2. Pages Exh.7-140-2 and Exh.7-140-3 are Figure 1 and Figure 2, respectively. The legend <br />on these figures appears to incorrectly identify the Section 16 Pond ditch as the permit <br />boundary. Please review these figures and correct the legends on these two figures to <br />accurately represent information. <br />Response: The original versions of Figures 1 and 2 showed the former permit boundary <br />which was in effect at the time the original design was permitted under TR-65. <br />With the approval of the South Taylor mine plan under PR-02, the permit <br />boundary is located off the map to the south. As such, the boundary is no <br />longer relevant and has been removed from the legend of Figures 1 and 2. <br />The legends of Figures 1 and 2 have been modified to accurately represent <br />the information identified on the map and are included with this submittal. <br />3. On the currently approved Exhibit 7, Item 140, Figures 1 and 2, there are two sediment <br />traps shown. These sediment traps are named Section 16 Sediment Trap 1 and 2. These <br />two sediment traps do not appear on the revised Figures 1 and 2. Please either replace <br />the sediment traps on the Figures or explain why they are no longer needed. <br />Response: The ten-year design event provided with this submittal shows that these traps <br />are not needed to achieve required discharge limits. Because of this, <br />Colowyo feels that it does not need to replace the sediment traps on the <br />proper Figures. <br />4. It is the Division's understanding that Colowyo is extending and reconfiguring the <br />Section 16 Pond ditch to capture runoff from the disturbed area until such a time as the <br />Section 21 Pond is constructed. As such, the ditch has been reconfigured and moved <br />from approximately Station 45+00 to its end-point. This moves the ditch approximately <br />250 feet to the southeast of its current location. This move increases the area of the <br />contributing watershed and catches the additional disturbed area runoff and diverts it to <br />the Section 16 Pond. The Division has some concerns with the design of the Section 16