2005-09-21_REVISION - M1978116

• Permit No: M1978116
• IBM Index Class Name: Revision
• Doc Date: 9/21/2005
• Doc Name: Responses to Issues of Preliminary Adequacy Review
• From: Cotter Corporation
• To: DMG
• Type & Sequence: TR4
• Media Type: D
• Archive: No

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COTTER
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SEP 2 12005 I~
September 20, 2004
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Steve Shuey
Colorado Division of Minerals and Geology ~
Grand Junction Field Office
101 S. Third St, Room 301
Grand Junction, Colorado 81501
RECEIVED `"~°~:i.:
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OCT 0 32005 °`~~>,
Aid/.
Division of Minerals and Geology
RE: Permit No. M-1~8-116 SM-18(Wnght) Mine,~Responses to Issues of Preliminary
Adequacy Revie~, for Technical Revision No. 4.'
Mr. Shuey:
The enclosed responses are to your ADEQUACY ISSUES 1. requested in your letter to
Cotter Corporation dated September 14, 2005. There is a map attached.
1. The map shows a recent survey of the as-built diversion ditch, dump and stockpile
areas, and the two redesigned catchment areas. Also shown are the capacities of
the two catchments and the drainage areas of each.
The calculations of a 10-yr 24-hr storm event, included as Appendix-B of the
Permit Amendment Application dated October 14, 2004, show that the
catchments of a dump area of 2 acres would need to contain a total of about
24,110 gallons. It was estimated at that time that approximately one-half of this
volume would flow to each catchment. As built, the total dump/stockpile azea is
only 1.5 acres, of which 29.3% will flow to the south catchment and 70.7% will
flow to the northern catchment.
The capacity of the north catchment is 28,700 gallons, obviously oversized. That
of the south catchment is 7,600 gallons, which would hold 29.3% of the original
estimate of 24,110 gallons, therefore, also oversized. The dimensions of the two
catchments are:
North-bottom azea 1500 ft2
top area 2370 ft2
height 2 ft
volume 3837 ft3
Cotter Corporation -West Slope Operations
P.O. Box 700, 28151 DD Road, Nucla, CO 81424 USA
28,700 gal
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