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Station Field Reading Map 33 <br />5 to 6.5 10 degrees 7 degrees <br />6.5 to 8.5 14 degrees 7 degrees <br />8.5 and up 16 degrees 16 degrees <br />Potentially the lower portion of this ditch is steeper than the design plan. This <br />could result in erosion of the riprap channel unless careful field design practices <br />are implemented. Some gullies have already occurred, especially from flow from <br />the north, above the substation road. Conditions are "worst case" at the present <br />time due to the lack of topsoil and vegetation. <br />At this time, the Division does not have a survey of the profile of the Prospect <br />Ditch, although the ditch is apparently to final grade along its entire length. <br />There is no practical reason to delay verification that the drainageway has been <br />reconstructed as per the approved plan with respect to the grade. However, with <br />the addition of riprap and the topsoiling of areas adjacent the ditch, it is unlikely <br />that any deviation with the approved plan would result in changes to the ditch. <br />Nonetheless, it should be recognized that a steeper grade than what was planned <br />and approved (and subsequently used in SEDCAD design for the Prospect pond) <br />could be a contributing factor to any future problem that could develop in the <br />watershed. <br />The Division requests that Colowyo submit a survey of the Prospect Ditch to the <br />Division for immediate review. <br />Response: The Prospect ditch has not been completed and currently does direct all surface runoff to <br />the Prospect pond due to cessation of reclamation activities. At this time the East Pit <br />intercepts the Prospect ditch location and requires future regrade in this area to finish the <br />construction of the approved ditch design. As Colowyo has always done in the past, the <br />Division will be provided with a full and complete as-built design accompanied by all <br />appropriate maps and descriptions as required by the Rules upon the completion of the <br />Prospect Ditch. Any significant deviations from approved overall ditch <br />dimensions/grading/placement will be fully quantified and justified by a professional <br />engineer and submitted to the division. <br />10. The issues raised in question 10 of the first and second adequacy letters were in <br />regards to the Prospect drainage. The issue was discussed in some detail at the 26 <br />February 2008 meeting between the Division and Colowyo. During the meeting <br />and in a follow-up letter dated 12 March 2008, the Division requested that <br />Colowyo provide a more detailed description and timing of the final regrading and <br />closure of the East Pit, including a map, or plate, and acreages of each regraded <br />Colowyo Mine • 5731 State Highway 13 • Meeker, Colorado 81641 <br />T +1 970 824 1500 9 F +1 970 824 1504 • www.rtea.com