2010-02-18_REVISION - M1997032

• Permit No: M1997032
• IBM Index Class Name: REVISION
• Doc Date: 2/18/2010
• Doc Name: EPP, Adequacy Response
• From: DRMS
• To: Denison Mines ‎(USA)‎ Corp.
• Type & Sequence: AM1
• Email Name: RCO
• Email Name: SSS
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF RECLAMATION, MINING LAND SAFETY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
February 18, 2010
Christy Woodward
Denison Mines (USA) Corp.
1050 17th Street - Suite 950
Denver, CO 80265
RECEIVED
FEB 2 3 2010
Divialon of Reclamation,
Mining a Safety
COLORADO
D I V I S I ON OF
RECLAMATION
MILTING
SAFETY
Bill Ritter, Jr.
Governor
Harris D. Sherman
Executive Director
Ronald W. Cattany
Division Director
Natural Resource Trustee
Re: Environmental Protection Plans, Adequacy Responses to DMO Amendment Materials, for Permit Number
M-1997-032, Van 4 Mine, Amendment AM-1.
Dear Ms. Woodward,
The Division has completed its review of the most recent adequacy submittal, pertaining to the EPP that is being
finalized for the Van 4 Mine permit. The submitted materials were received at the Division's Durango office on
January 4, 2010, which was before the decision date. The complexity of the materials, however, required additional
review time by Division staff, beyond the decision date. The submittal is nevertheless considered timely and the
Division will proceed toward a decision on the amendment.
The following paragraphs contain comments by the Division, for all issues and recent responses provided by Denison
that the Division still considers to be inadequate. (The Division's comments, below, are not necessarily arranged in
the same order as in previous correspondence.) All topics considered to be adequately addressed at this time are not
discussed further herein.
Please see the attached memo from the DBMS geochemist for discussion and comments regarding Uranium as a toxic-
forming material, and Addendum to the hydrologic evaluation. You may respond directly to me regarding those
questions.
Ore pad liner.
Justification: As shown by UNSAT-H modeling, the potential for percolation of water to groundwater resources from
the waste rock and ore stockpiles does exist though it the model indicates that it may be minimal. As such, the
requirement for lined ore pads is justified.
The site map depicts an acceptable liner location. It is shown to be 100 ft x 100 ft, a standard size which comports
with the written description.
Geotextile Material: The Division and Denison agree that due to the inherent limitations of the onsite soil for use as a
soil liner, an impermeable geo-membrane is required. Denison has proposed using a 30-mil PVC liner, but the
Division recommends that PVC not be used, since there is evidence that can degrade fairly fast, even when covered.
The Division suggests that an LLDPE membrane be used. Even when exposed to ultraviolet light, LLDPE has a
functional life of about 12 years before it starts to degrade. Since the liner will be used in an area where ore is stored
in piles less than 15 feet in height and which has low potential for runoff, a 30-mil LLDPE liner membrane represents
the minimum acceptable thickness. Please forward the appropriate specifications for this different liner material.
Office of
Office of
Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines