2010-12-15_REVISION - C1981019 - Laserfiche WebLink

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New Adequacy Questions Based on Colowyo's 1 June 2010 Responses 35. Colowyo has provided Map 41 - Watershed Boundaries for Hydrologic Modeling- South Taylor Area, which shows the post-mining drainage channels for the South Taylor Pit area. On this map several minor tributaries are shown on the east edge of the revised South Taylor Pit. These tributaries are labeled TRIB. A through TRIB. I. These tributaries are meant to convey flow from the reclaimed surface to the Section 28 and Section 21 Ponds. Several of these tributaries do not appear to be topographically controlled. That is, they appear to have been placed in their original configuration or location, at the intercept point with the undisturbed drainage, with no regard as to whether there is really a drainage in the reclaimed topography above the undisturbed drainage location. Because the reconstructed post-mining topography does not create a drainage in these tributary locations, it is unclear how water will be conveyed into the natural, undisturbed drainage and into the appropriate sediment pond. The tributaries that do not appear to be topographically controlled are B, D, E, G and H. Please review TRIB. B, D, E, G and H to determine if their locations are appropriate for a final drainage channel. Please either change the proposed drainage location(s), the post-mining topography in these locations or give a detailed explanation describing how these tributaries will perform as designed. Please update all SEDCAD modeling and maps as necessary. Response: The Postmining topography has been modified to show a small drainage V shape in the contours for the tributaries labeled Trib. A through Trib. I in the areas mentioned above. All of these channels have been located to tie to natural channel segments directly below the PMT tie-in boundary. 36. Colowyo has removed the Section 28 Collector Ditch from Map 41A. , Another missing item is the Section 16 Pond Ditch (and extension), which is critical for sediment control for the east side of the South Taylor Pit and the X-Pod area. Please return the Section 28 Collector Ditch to Map 41A and add the Section 16 Pond Ditch (and extension) to Map 41A. Response: The requested changes have been made. All ditches on the map have been reviewed with this submittal and the stationing modified to show the ending station number. The ditches have also been checked against the summary ditch tables (presented in Volume 2C Exhibit 7, Item 14, Table 1 and in Volume 13 Table 1, Exhibit 7-20, Part E). Ditch profile information on Maps 33 and 33A have likewise been reviewed. As previously noted, the drawing files which create Map 41 and Map 41A have been combined into a single drawing which should eliminate these problems in the future. The Section 28 Collector Ditch, Section 16 Pond Ditch and the Section 16 Pond Ditch Extension have been added to Map 41A. 37. Currently approved Map 41 and proposed Map 41A show the watershed boundaries for hydrologic monitoring for the South Area and the South Taylor Area, respectively. These maps also show the permanent, post-mining drainage channel locations. There are several sections in Township 3 North that are duplicated on both maps. These sections are 9, 16, the east quarter of 17 and the north half of 21. Several of the post-mining drainages, however, are not duplicated on Maps 41 and 41A. This has led to several inconsistencies between the approved Map 41 and the proposed changes to the East and West Taylor Fills, South Taylor Mine Plan and South Taylor post-mining topography (as shown on Maps 19B, 23A and 41A). The following are the inconsistencies between the approved Map 41 and the changes proposed on Map 41A that need to be fixed. Since the mining areas cross- over, the Division requests that all common drainages from Sections 9, 16, 17 and 21 are