GENERAL54344

• Permit No: C1983058
• IBM Index Class Name: General Documents
• Doc Date: 10/14/1993
• Doc Name: RECLAMATION ISSUES TWIN PINES LIMITED INVESTMENT TWIN PINES MINE 2 C-83-058
• From: DMG
• To: LARRY WHITE
• Permit Index Doc Type: GENERAL CORRESPONDENCE
• Media Type: D
• Archive: No

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STATE OF

COLORADO
DIVISION OF MINERALS AND GEOLOGY
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Department of Natural Resources
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1313 Sherman 51., Room 215
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Denver, CO 80203 •
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Phone: [phone] revc
FAX:[phone]
Roy Romer
October 14, 1993 Governor
Michael B. Long
Division Dnecror
Attn: Larry White
1650 M Street
Penrose, CO 81240
Re: Reclamation Issues, Twin Pines Limited Investment
Twin Pines Mine ~2, (C-83-058)
Dear Larry:
The Division has reviewed your proposal concerning reclamation
issues, discussed on August 31,1993 and have the following
comments.
1. Concerning the Lewis Gulch Fill, the Division stands by the
approved Twin Pines reclamation plan, and Twin Pines' previous
commitment, to remove the fill from the Lewis Gulch. The Division
has determined that the permittee's proposed designation of the
fill as a "sediment control structure", and the permittee's
subsequent request to leave the fill in the gulch for this purpose,
is inappropriate, as the fill has a culvert installed in the bottom
of the fill that would allow sediment to pass through the fill
without being treated. Furthermore, the potential exists for
sloughing of drainage sideslopes that could cause the culvert to
back up with an instantaneous sediment load. Additionally, since
the original design purpose was for a truck turn-around, and trucks
will no longer be utilized on the site, the fill must be removed.
Another consideration in this decision concerned whether the final
reclamation topography would meet the approximate original
topography. The Division is aware that the Twin Pines Mine #2
operates within pre-law areas, and that achieving the approximate
original contours (AOC) will be difficult. However, with the
additional sediment from the fill, AOC can better be accomplished.
Indeed, accomplishing any stable gradient in the two upslope bench
areas of the facility and substation is paramount. Use of slough
material such as from the area above the substation roadcut for a
substitute, if removed from its native location, would cause
additional instability in the area, and therefore, must remain in
place for stability to be reached naturally. Removing the toe of
the sloughed material for reclamation backfilling would also cause
instability in the road cut areas, and as such should be avoided.
2. Since the fill is to be removed, the adjacent downstream
sediment pond structure must be reconstructed during the backfill
and grading process, since the pond and the Lewis Gulch Fill