REV04726

• Permit No: C1981025
• IBM Index Class Name: Revision
• Doc Date: 10/21/1994
• Doc Name: NORTH THOMPSON CREEK MINES C-81-025 TR-17
• From: DMG
• To: BARBARA PAVLIK
• Type & Sequence: TR17
• Media Type: D
• Archive: No

iii iiiiiuiiiiii iii
999
STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Depanment of Natural Resources
1313 Sherman SL, Room 215 r{~

Denver, Colorado 80203 I
~~~

Phone: [phone] II
FAX: [phone]
DEPARTMENT OF
NATURAL
RESOURCE
DATE: October 21, 1994 Roy Romer
Governor
TO: Barbara Pavlik lame, s. Eo<hnead
Execmive Director
Michael 8. Long
FROM: Susan Burgmaier Division Director
Erica Crosby f.SC..
RE: North Thompson Creek Mines (C-81-025)
Technical Revision 17
We have completed a review of the above mentioned technical revision. We reviewed the
operator's estimated runoff for and design specifications of ditches D-2A, D-2B, D-11, D-6, D-7,
D-12, and Dom; and culverts C-2 and C-6 (two C-6 culverts). The estimated runoff, ditch sizing,
and culvert sizing were all appropriate, and therefore we would recommend approval of those
designs. There is, however, one concern with the check dam designs for the dams proposed to
be placed at the former locations of P-6, P-7, and P-8.
The predicted velocities in ditches D-6 and D-7 will likely be erosive, so the MINREC
has proposed check dams to lessen velocities. The dams at former pond locations P-6
and P-7 are proposed at the end of long ditch stretches. It is possible, then, that erosion
may occur upgradlent of the dams. Since the predicted velocFties are only slightly above
those deemed erosive, the Division will approve of the proposed plan. We will request,
though, that MINREC include in the permFt pages a commrtment to monitor the ditches
for erosion, and enhance the ditch protection if necessary.
As we discussed with you, we did not review the revised Drawing No. D-2-3, which provides the
locations of all culverts on the Uttit Train Loadout haul road. Since we are not familiar with
the site, we would be unable to determine the accuracy of that map. If after reviewing the map
you note changes to culvert sizes or locations, let us know, and we would be happy to review any
revised designs.
If you or the operator have questions or need more information, let us know.
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