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2013-05-16_REVISION - M1990057
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2013-05-16_REVISION - M1990057
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Entry Properties
Last modified
6/16/2021 6:19:07 PM
Creation date
5/21/2013 7:36:08 AM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
M1990057
IBM Index Class Name
Revision
Doc Date
5/16/2013
Doc Name
TR Submittal
From
The Union Milling Company
To
DRMS
Type & Sequence
TR4
Media Type
D
Archive
No
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tailings disposal capacity for a more efficient concentrating system and increased tails reporting to the <br />TSF. The historical Phase 1 TSF embankment compaction is inadequate for current production requiring <br />complete removal of the existing embankment and reconstruction of the TSF facility with a lined facility. <br />The reconstruction honors the original permit parameters as follows: <br />• The same 4.6 acre tailings disposal facility (TSF) is utilized. <br />• The pond excavation at a maximum 21 ft depth does not impact the known aquifers at 80 -100 ft <br />below the surface. <br />• The tailings impoundment dam will be constructed from available onsite soils borrowed from the <br />tailings disposal area as outlined in the recommendation of CTL/Thompson, Inc., Consulting <br />Geotechnical and Materials Engineers, Permeability Study Tailing Pond Area, April 10, 1990, <br />presented as Appendix A, Slope Stability Evaluation Tailings Pond Embankment and Future <br />Tailing Slope, July 8, 2011. <br />• The TSF will be constructed as a zero discharge facility with 3 ft of freeboard in accordance with <br />the Probable Maximum Precipitation Estimates — United States Between the Continental Divide <br />and the 103`d Meridian. <br />• Non disturbed drainage is diverted around the TSF while disturbed area drainage from the mill <br />area disturbance reports to the TSF. <br />• The observation well down gradient from the 4.6 acre TSF area will be maintained in its current <br />location and monitored. <br />• Topsoil, in accordance with the topsoil plan will be removed and stockpiled. <br />Additionally, the proposed TSF facility further commits to: <br />• Stability analysis initiated by CTL Thompson, Inc. May 12, 2011, on samples collected from the <br />existing compacted fill embankment, 2 additional holes drilled to compliment and confirm the <br />1990 permeability test hole data, and the CTL Thompson Letter Report of July 8, 2011, presented <br />as Appendix A, Slope Stability Evaluation Tailings Pond Embankment and Future Tailing Slope, <br />July 8, 2011. Subsequently, CTL Thompson issued an update to the July 8, 2011 Report, <br />presented as Appendix B, Slope Stability Evaluation Tailings Pond Embankment and Future <br />Tailing Slope, August 17, 2011. <br />• A 2.5:1 (horizontal to vertical) outside face; and a 2:1 interior face embankment dam with a 12 ft <br />wide crest berm. <br />• A �Ze(),'ynthetic12in mifiiniain clayt+nder liner of 1 x 10.6 cm/sec permcabihtk (or less). or <br />cqui,alent material liner, <br />'s <br />rellerinstallcd with the leak detection drainage net system and the 45 -mil polypropylene <br />geomembrane. <br />• A seepage /leak detection drainage net system between the gcos�nthcuc clay luicr}aycf and the <br />syfifhetie neF 15 -mil polypropylene _,corneinbrane with the collection system located in the <br />northwest corner of the impoundment, and the pond impoundment bottom sloping at 0.5% 40pe <br />to the northwest. <br />• A synthetic pond liner of 45 -mil & olypropylene &Geomembrane or equivalent. <br />• Compaction testing during construction. <br />r <br />N11990-057 D1aN 14,2013,! <br />Formatted: Font 11 pt <br />Formatted: Font: 11 pt <br />Formatted: Font: 11 pt <br />Formatted: Font: 11 pt <br />Formatted: Font: 11 pt <br />Formatted: Font: 11 pt <br />Formatted: Font: 10 pt, Bold <br />Formatted: Right <br />Formatted: Font: 10 pt, Bold <br />
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