REV07600

• Permit No: C1981019
• IBM Index Class Name: Revision
• Doc Date: 7/7/1994
• Doc Name: COLOWYO MINE C-81-019 TR-29
• From: DMG
• To: TONY WALDRON
• Type & Sequence: TR29
• Media Type: D
• Archive: No

III IIIIIIIIIIIIIIII
999
STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Depanmem of Natural Resources
1313 Sherman Si., Room 215 yF

Denver, Colorado 8020] II
~~
y
Phone: [phone] Il
FAX: [phone]
DEPARTMENT OF
NATURAL
RESOURCE
DATE: July 7
1994 Roy Romer
, Governor
TO: Ton Waldron
y lames 5. Lochhead
Di
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i
ve
xecut
rector

FROM:
Susan Burgmaier Michael B. Long
Division Director
RE: Colowyo Mine (C-81-O1~q
Technical Revision 29
I have reviewed Colowyo's submittal for the above mentioned technical revision application.
Based on my review, I would recommend approval of the proposed ditch designs for drainage
control of the additional West Pit area disturbance. I do have other concerns wFth the plan that
I would like to bring to your attention, but they don't really have any effect on the ditch proposal
itself.
The new disturbance, in the southwest pit area (drains to Coal Road ditch) and in the western
exp]oration azea (drains to Temporary West Pit ditch), was not in included in the modelling
efforts for sizing the West Pit pond. The "worst casen disturbance assumption used to determine
the necessary capacityy was a maximum of 125 acres of stripped area. There is a commitment
(associated with TR 25) in the Colowyo permit that states that as .long as the West Pit pond is
the sole control structure, the 125 acre maximum will be observed. Based on a sketch of the
stripped area provided by Juan Garcia, it appears that the stripped area draining to the West
Pit pond is now just over 200 acres. Juan said that pit development has begun, but I am not
sure of its extent. If there has not been a pit developed, then Colowyo is out of compliance with
the commitment in the application, and has exceeded the design limits of the West Pit pond.
I think we should find out how much area is stripped and whether or not they have any pit
developed. If there is a pit developed, we should find out what the approximate size is and
whether or not they are routing overland flow into the pit versus the pond. It might be a good
idea to get aerial photos of the area as soon as possible. I spoke to Harry Ranney,about flying
the area, and he said to let him know if and when we need it done. -
Let me know if you need have questions, need additional information, or want me to follow up
on this.
c: Larry Routten
SLB\070799. WP