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case hydrologic condition. Please demonstrate, through SEDCAD modeling, that the <br />Prospect Pond spillway system complies with Rule 4.05.9(2)(c)(ii) for the 25-year 24- <br />hour storm event for the 2017 watershed condition. <br />Colowyo has provided new, proposed generalized stock tank design as Figure 2.05-6. <br />This stock tank design will be used to construct the five stock tanks proposed in the <br />Prospect Watershed of the East Pit. Colowyo also has an approved stock tank design in <br />Exhibit 7, Item 11, which was used to construct all of the stock tanks that are currently on <br />the ground in the East Pit and Section 16 Pit reclamation. Colowyo will need to retain <br />the stock tank design in Exhibit 7, Item 11 as it is still valid for the existing stock <br />tanks. The Division recommends that Colowyo include Figure 2.05-6 in Exhibit 7, <br />Item 11 as well, so all stock tank designs are in the same location. The Division also <br />requests that Colowyo provide a cover page for Figure 2.05-6 as well as a short <br />description stating which stock tanks this design will be used to construct. Finally, <br />as discussed in the 13 October 2010 meeting, Colowyo needs to update Figure 2.05-6 <br />to accurately represent the stock tanks as they will be constructed in the prospect <br />watershed, including the routing of the runoff for stock tanks not constructed <br />directly in the post-mining drainage channels. <br />This concludes the preliminary adequacy review for the Colowyo Mine's Technical Revision 87. <br />Please contact me at (303)866-3567 X8145 if you have any questions or comments. <br />Sincerely, <br />James R. Stark <br />Environmental Protection Specialist <br />cc: Sandy Brown, CDRMS <br />Matt Guptill, Colowyo