2010-07-09_REVISION - C1981019 (4)

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will need to be submitted no later than 25 June 2010 so it can be implemented in the 2010 reclamation season. Colowvo's Response: As discussed previously, if and when additional structures requiring approval are planned for, the appropriate permitting strategy will be implemented. Colowyo will be seeking approval of several standardized sediment control structure designs of both the temporary and permanent variety that can be incorporated into reclamation backfill and grading plans and previously graded areas that will reduce peak flow and limit sediment transport from newly reclaimed areas by the end of October, 2010. Current SEDCAD models for these drainages demonstrate compliance with model assumptions. These additional structures will provide additional sediment, velocity and peak flow control to areas that already demonstrate compliance. Colowyo will not pursue incorporation of these structures into the SEDCAD models unless it is necessary to demonstrate compliance based on more acres reporting to the discharge structures according to the one, two and three years or older model criteria, where these areas are not otherwise isolated by in pit sumps or other means. 10. Map 33 shows the post-mining drainage channels for the Colowyo Mine. This sheet has a drawing of the Prospect Ditch (with a length of approximately 3,300 feet). There is also a smaller channel profile farther down on the sheet that shows the Prospect Ditch-Lower Segment (approximately 1,500 feet). This lower segment of the Prospect Ditch is not a continuation of the Prospect Ditch since the ending elevation of the Prospect Ditch is approximately 7,025 feet and the starting elevation of the Prospect Ditch-Lower Segment is approximately 7,125 feet (it is impossible for the two segments to join up). Additionally, there is not a Prospect Ditch-Lower Segment shown on Map 41 - Watershed Boundaries for Hydrologic Modeling (which shows all of the post-mining drainage channels), or any other map (specifically Map 12 - Hydrology South Area). Finally, there does not appear to be a SEDCAD design for this ditch in Exhibit 7. Please provide the Division with information regarding this ditch segment, including its location on the appropriate maps (Map 12 and Map 41) and SEDCAD modeling in Exhibit 7. Colowyo's Response: The Prospect Ditch - Lower Segment refers to the native area drainage course that is comprised of a historical armored bedrock channel. This area was included on Map 33 for reference purposes only and to demonstrate that a man-made channel was not required or desirable to convey flow from stormwater/snowmelt events below the actual disturbance footprint of the Prospect Drainage. Colowyo has no intention of creating a man made ditch through this corridor as it successfully functions, has naturally evolved, and does not cause additional disturbance to create. This reference will be continued for demonstrative purposes only and will not be included in additional locations. 11. Colowyo has constructed sumps to control runoff from and around the haul road to the Gossard Loadout along the access road in Taylor Draw, to the West Pit Pond, East Taylor Pond and West Taylor Pond. These sumps are best management practices and are not considered a part of the sediment control system. Sump 5 does not appear to be functioning properly. There is almost always mud and water backing up along the Taylor Draw road at the location of this sump, occasionally drying in the late summer months. This accumulation of mud and water is not what the sump was intended to do. Colowyo must provide a plan to remedy this problem. Please include a timetable for the completion