2010-03-29_REVISION - C1981019 (3)

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Colowyo Response: Please refer to Volume 18, Exhibit 7, Item 27. 22. Colowyo has not provided any information related to the post-mining drainage channels. The submittal stated that this information is contained in Exhibit 7, Item 23, Part E but it has not been included. Details required b;y Rule 4.05.3 includes, but is not limited to, a map showing the channel locations, channel profiles, channel designs and all necessary SEDCAD modeling. Colowyo Response: Volume 18, Exhibit 7, Item 25, Figures I through 11 provide Post-mining Case Hydrologic Assumptions of the drainage areas and channels. Associated text in Volume 18, Exhibit 7, Item 25 provides the results of all SEDCAD modeling for the post-mining channels. Map 41B - Watershed Boundaries for Hydrologic Modeling shows plan view locations of the design ditch channels and drainage boundaries. Map 33C - Post-mining Permanent Drainage Profiles provide the detailed profiles of the Postmining permanent drainages. Rule 4.05.4 - Stream Channel Diversions and Stream Channel Reconstruction 23. On page 107 of Section 4.05.4 Colowyo states that they are planning to divert three streams in the Little Collom X and Collom Lite Pits. These stream channels are two small tributaries of Little Collom Gulch (diverted around Little Collom X) and the main channel of Little Collom Gulch. The PR-03 submittal states that the information is contained in Section 2.05.6 and Exhibit 7, Item, 23. The required information is not, however, included. Please provide detailed descriptions, plans, channel profiles, maps and SEDCAD modeling for all proposed stream channel diversions within the permit area. Additionally, please provide a detailed plan for reconstruction of the three affected stream channels. Colowyo Response: Volume 18, Exhibit 7, Item 25, Figures I through 11 provide Postmining Case Hydrologic Assumptions of the drainage areas and channels. Associated text in Volume 18, Exhibit 7, Item 25 provides the results of all SEDCAD modeling for the post-mining channels. Map 33C - Post-mining Permanent Drainage Pro ales provide the detailed profiles of the Postmining permanent drainages. Rule 4.05.13 - Ground Water Monitoring 24. Please review the baseline groundwater information, the Office of the State Engineer well records and proposed groundwater monitoring program specific to establishing a groundwater point (or points) of compliance at the Colowyo Coal Mine-Collom project area. Pursuant to Rules 4.05.13(1)(a) and (b), please evaluate the need for points of compliance and provide the Division with a detailed narrative of your findings, including the location(s) of the point(s) of compliance. Colowyo Mine C-1981-019 page 10 of 16 25 March 2010 Permit Revision 03 - Collom Permit Expansion