APPCOR11485

• Permit No: C1994082
• IBM Index Class Name: Application Correspondence
• Doc Date: 1/19/1995
• Doc Name: YOAST MINE C-94-082 APPLICATION REVIEW COMMENTS
• From: DMG
• To: SUSAN BURGMAIER
• Media Type: D
• Archive: No

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STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Deparlmenl of Natural Resources
131 3 Sherman Si., Room 215
Denver, Colorado 80207
Phone: [phone]
FAX (30J) 8328106
To: Susan Burgmaier, Environmental Protection Specialist
From: Bruce Stover, Technical Support
Date: January 19, 1995
Re: C-94-082 Yoast Mine Application Review Comments
II~~
DEPARTMENT OF
NATURAL
RESOURCES
Roy Romer
Governor
lames 5. Lochhead
EeecWive Director
Michael B. Lang
Division Dnecror
I have reviewed Tabs 6, 12, 13, and 20, as well as discussing certain aspects of Tabs 7, 15,
16, and 17 with Barbara Pavlik. Additionally, I have compiled a preliminary landslide
geologic map of the permit area from the aerial photographs you provided. The following
are my comments and questions on the adequacy of the application.
Tab 6 Geology and Overburden Assessment
' The bedrock geologic mapping is adequate, however, the engineering/surficial
geologic mapping provided is not. Exhibit 13-12 does not show surfical materials
such as landslides and thick colluvium which will affect mining, some facilities, and
potential slope stability during the mining and post mining period. (Please see
attached preliminary photo-interpretive map). There appear to be some areas of
landslide deposits ranging from very old, to active/very young, which will have a
bearing on mining and development of certain parts of the permit area. In order to
evaluate specific siting and mining alternatives, these deposits/features should be
shown on the surfical geologic mapping, and be incorporated into the permit
documents.
Tab 12 Mining Plan
' As noted above, there are some areas of landslides which will potentially affect the
plan, but which are not discussed or recognized in the permit documents at this time.
These areas should be delineated, and the mining plan should address how
potentially unstable areas and active landslide areas will be affected/ mitigated
during the mining operations, specifically:
• The "neck pit" will be developed through a significant landslide/colluvial
deposit which could adversely affect pit wall stability, and future topsoil
stockpile locations.
• A potentially unstable area on the west upper slopes and gulch of the pond
011 drainage could impact road or ditch construction. The 1999 pit could