REV04754

• Permit No: C1982055
• IBM Index Class Name: Revision
• Doc Date: 3/14/1995
• Doc Name: RATON CREEK MINES C-82-055 TR 18 CHECK DAM DESIGNS
• From: DMG
• To: ENERGY FUELS MINING CO
• Type & Sequence: TR18
• Media Type: D
• Archive: No

DIVISION OF MINERALS AND GEOLOGY
Depatlment of Natural Resowces
1313 Sherman 51., Room 215
Denver, Colorado 80203
Phone: [phone]
FA%:13031832-8106
Mazch 14, 1995
Mr. Allen S. Weaver
Energy Fuels Mining Company
P.O. Box 449
Florence, Colorado 81226
Re: Raton Creek Mines (C-82-055): Technical Revision No. 18
Check Dam Designs
Dear Mr. Weaver:
II~~
DEPARTMENT OF
NATURAL
RESOURCES
Roy Romer
Governor
lames 5. Lochhead
EtKUlive DireClor
Michael H. Long
Division Direclo~
The Division has reviewed your revision for two check dams at the Raton Creek Mine (C-
82-055). The Division hydrologist has identified several concerns as follows:
1) The Division considers that the two structures aze check dams that impound water,
requiring compliance with Rule 4.05.9, "Impoundments,' but not Rule 4.05.6,
"Sedimentation Ponds,' except where Rule 4.05.9 refers to specific sections of Rule
4,05.6. The Division does not define them as sedimentation ponds because Rule
1,04(115) defines a sedimentation pond as a primary structure. These check dams
are secondary structures because they are not required to treat the disturbed area
runoff. There already is a primary sedimentation pond. Rule 1.04(115) further states
that secondary sedimentation control structures are not considered sedimentation
ponds.
The Division asserts that the two check dams impound water. First, there is about
1.6 to 1.8 feet of water storage capacity below the lowest culvert in the embankments,
making the two dams capable of impounding water. Second, it appears to that the
culverts are not large enough in diameter to quickly pass water out of the structure
without allowing a significant amount of water to back up for an extended length of
time. For comparison, a rock check dam would not be considered an impoundment
because the dam would leak like a sieve. Some water might back up behind the
dam, but not a lot and not for a significant amount of time.
For the sake of this review, the Division considered the two structures to be
impounding check dams and require compliance with Rule 4.05.9.
S r~~'I~II~II~~~~~ ~II
sss
STATE OF COLORADO
2. Rule 4.05.9(2) refers to Rule 4.05,6(11), and Rule 4.05.6(11)(f) requires that the
inslope and the outslope of the embankment add up to not steeper than 5:1 with