2011-09-09_REVISION - M1981185 ‎(43)‎

• Permit No: M1981185
• IBM Index Class Name: REVISION
• Doc Date: 9/9/2011
• Doc Name: Response to Fifth Adequacy Letter
• From: R Squared, Inc.
• To: DRMS
• Type & Sequence: CN1
• Media Type: D
• Archive: No

Mr. Wallace H. Erickson
Response to August 22, 2011 Cazier Memorandum
September 9, 2011
Page 8
Table U -6 (Drainage Flow Analysis Above May Day No. 2). Wildcat is submitting a
revised Exhibit D, Attachment D -3, Figure D -1, Stormwater Control Plan, modifying the
typical channel width bottom to show a width of 4 feet. See Attachment 3.
Response to Adequacy Issue No. 10.d.
Wildcat will add a bullet under the Quality Assurance section at Page 5 of
Attachment D -3, as follows:
• Observing rock check dam immediately downstream of the culverts is placed
far enough downstream such that it does not create a tailwater condition for
which the culverts are not designed leading to overtopping flows.
Attachment D -4, Chief Drainage and Portal Work Plan and Lamb Affected Area
Little Deadwood Gulch
Adequacy Issue No. 11.
The approach to the drainage reclamation in the vicinity of the Chief Portal is
unacceptable. On June 2, 2011 DRMS met with George Robinson on site and
specifically discussed the approach Wildcat should implement in the reclamation of
Little Deadwood Gulch in the vicinity of the Chief Portal. We agreed that all mine
waste needs to be removed from the drainage. There are many reasons for this approach.
The primary reason is to ensure the invert of the reclaimed channel is at an elevation
sufficiently low enough to pass the peak flow from the 100 -year, 24 -hour design storm
without allowing any flows into the chief portal. The proposed design in the work plan
uses a narrow berm to segregate gulch drainage from the portal. This is not a long term
solution. The berm will eventually fail or erode away, subjecting the portal to flows
from the drainage. DRMS understands that CDPHE has also required all mine rock be
removed from the drainage in this area. The applicant is required to resubmit the entire
work plan for the Little Deadwood Gulch in the vicinity of the Chief Portal to
demonstrate how all the mine waste will be removed.
Response to Adequacy Issue No. 11.
Wildcat has determined that removing all mine waste from the Chief Drainage
would de- stabilize the Chief Portal and adjacent bench. For this reason, Wildcat
proposes a two -step removal of mine waste from the Chief Drainage. First, Wildcat will
remove part of the mine waste as specified in Attachment D -4 during active mining
operations. Second, Wildcat will remove all remaining mine waste during reclamation.
Wildcat is submitting a revised reclamation plan reflecting that it will remove
historically mine rock from the drainage and re- establish the approximate pre -mine
drainage channel. See Attachment 3 (Figure F -5A).
DEN 97, 591, 786v1 9 -9 -11
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