1993-10-27_REVISION - M1977378 ‎(6)‎

• Permit No: M1977378
• IBM Index Class Name: REVISION
• Doc Date: 10/27/1993
• Doc Name: Response
• From: DMG
• To: Town of Silverton
• Type & Sequence: TR14
• Media Type: D
• Archive: No

999
STATE OF COLOKADO
DIVISION OF MINERALS AND GEOLOGY
Department of Natural Resources / �/� a�'oe co,��
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1313 Sherman St.,Room 215 #
Denver,CO 80203 � *
Phone:[phone] 'n tit
FAX:[phone] 0 Roy Romer
Governor
,,October 27, 1993 Michael B.Long
Division Director
Mr. William T. MacDougall, Mayor
Town of Silverton
P.O. Box 250
Silverton, CO 81433
Re: American and Terry Tunnel Bulkheads, Sunnyside Gold Corporation,
Sunnyside Mine, File No. M-77-378
Dear Mr. MacDougall:
The Colorado Division of Minerals and Geology (Division) is in possession
of your letter dated September 30, 1993 regarding the technical revision
that details placement of concrete bulkheads in the Sunnyside Mine. On
October 27, 1993, the Division scheduled this matter for a hearing before
the Colorado Mined Land Reclamation Board (Board) and issued a
recommendation to approve the revision (see attached documents) . The
Division would like offer you, and the Town of Silverton, the opportunity
to participate in the hearing. If you or your representative cannot
attend the hearing, I will make certain that the concerns addressed in
your letter are heard by the Board.
As to your specific concerns, I believe that all but paragraph d in your
letter have been addressed, either in the technical revision submittal
package, or through the Division's adequacy review for this revision. I
will provide a brief response to each of your concerns here, but would
refer you to the technical revision documents for a more in-depth review
of each of your concerns. The documents are available for public view in
Denver, and will be placed on permanent file with the San Juan County
Clerk and Recorder if this revision is approved by the Board. In the
mean time, I am certain that Sunnyside Gold would make these documents
available for your review if you contact the mine office.
Each of your concerns is addressed in the same order as in your letter:
Item a)
The bulkheads are over-designed to resist failure in thrust (blow-out
failure) , even in the event of a large earthquake in the vicinity of the
mine. If the bulkheads were to degrade over time (an unlikely event) ,
and were no longer able to impound water, the mode of failure would be
leakage around the edges of the concrete, and a gradual draw down of the
mine pool.
Item b)
Flooding of the underground workings will essentially exclude oxygen from