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2009-01-14_PERMIT FILE - C1980007A
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2009-01-14_PERMIT FILE - C1980007A
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Last modified
8/24/2016 3:39:55 PM
Creation date
3/20/2009 9:24:25 AM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
C1980007A
IBM Index Class Name
Permit File
Doc Date
1/14/2009
Section_Exhibit Name
2.05.3 Operation Plan - Permit Area
Media Type
D
Archive
Yes
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West Elk Mine <br />Impacts of Overtopping Hydrologic Structures <br />All diversion structures are designed for use throughout the life of the West Elk Mine. See <br />Exhibit 44, Exhibit 47, and Exhibit 66 for details of the design of these structures, including <br />stability analyses, where appropriate. <br />The ditches have been designed and constructed to follow existing drainage routes. Overtopping <br />the collection and diversion ditches would create localized flooding of the immediate area; <br />however, damage would be minimal as flows would most likely enter the next downstream ditch <br />or culvert and flow to the sediment pond. The future access road to the upper waste rock <br />disposal area would be closed to traffic during such times. Since most of the ditches are lined <br />with shotcrete or other such energy dissipaters, problems would be minimal. <br />Ponds MB-1 and MB-2R have been shown to safely pass through the spillways the runoff from a <br />100-year precipitation event into the North Fork of the Gunnison River. Overtopping <br />impoundment structures would create erosion along the embankments and contribute to localized <br />flooding. In the "greater than a 100-year flood precipitation event" the south bank of the North <br />Fork would experience more damage from the river itself than from overtopping the ponds. <br />Furthermore, the facilities on the south bank are above the floodplain elevation and should <br />experience minimal damage. <br />Collection and Diversion Channels <br />t"'rnee .Cnrtinn <br />The cross-section of a typical collection and diversion channel is shown in Exhibit 47 and the <br />minimum ditch designs are shown in Exhibit 66. Exhibit 66 discusses the hydrologic design of <br />ponds, channels, and culverts in the area of the surface facilities, including the Sylvester Gulch <br />Facilities Area. The locations of the culverts used for collection and outfall may be found on <br />the Plot Plans showing Hydrologic Structures in Exhibit 43 and drawings in pertinent <br />Appendices. The hydrologic design of the RPE pond is located in Exhibit 70 and Exhibit 66. <br />Design Dimensions <br />The hydrologic criteria of the diversion and collection channels, are located in Exhibit 66. <br />Exhibit 46, Exhibit 47, Exhibit 49, Exhibit 66, and Exhibit 70 contains all the construction <br />specifications for Ponds MB-1 through MB-5, the SG-1 pond, and the RPE pond (note that <br />MB-2 has been redesigned and is included in Exhibit 66 as MB-2R, and pond MB-6 no longer <br />exists). The designs for the trash racks that may be installed on some culverts, 30 inches or <br />less minimum cross-sectional dimension are in Exhibit 43. Acreages of drainage areas relating <br />to certain diversion and collection channels are shown in Exhibit 66. <br />t"'~ilvnrte <br />2.05-39 Revised November 2004 PR10; Rev. March 2006; Rev. Apri12006 PR10; Rev. May 2006 PRIG; Rev. January 2009 MR-350 <br />
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