DRC-2011-004189 - 0901a06880224618

DENISO
MINES
Denison Mines (USA) Corp.
1050 17th Street, Suite 950
Denver, CO 80265
USA
Tel : [phone]
Fax: [phone]
www.denison mlnes.com
April 19, 2011
VTA ELECTROMfC RLE AND OVERNfGKT DELfVERV
Mr, Rusty Lundberg
Executive Secretary
Utah Radiation Control Board
Department of Environmental Quality
195 Norm 1950 West
PO Box 144810
Salt Lake City, Utah 84114-4820
Re: Denison Mines (USA) Corp.
State of Utah 'i1e.{2} Byprodtfct Matenai Lrcerrse # UT1900479
White Mesa Mill, Blanding, Utah
License Condition Number 12.3 - Annual Technical Evaluation Report
Request for Information, March 15, 2010
Dear Mr. Lundberg:
We are responding to the March 17, 2011 Request for Information from Dave Rupp asking for additional
clarification on the November 2010 Annual Technical Evaluation of the White Mesa Mill Tailings Management
System Mr. Rupp's comments are restated below, in italics, followed by our response.
The subject ATER has been reviewed, and we have the following comments:
1. On page 8, the last sentence of the first paragraph states that. "Upon completion of the south
Cell 4B dike it will become the new boundary and will have movement monuments installed."
Our follow-up question to this is what is the status of the installation of these monuments?
The movement monitors on the Cell 4B dike were installed on December 6, 7 and 8, 2010.
2. Under the Site Photographs tab of the ATER, photo 16 shows tree-like plants growing on the
interim cover of Cell 2. These trees must be removed.
The tree-like plants on the Cell 2 interim cover have been removed. The attached photographs document the
removar process and results.
Letter to Mr. Rusty Lundberg
April 19,2011
Page 2
3. Photo No. 28 shows soil on the south of the dike which appears to be not compacted. Please
justify why this soil is not compacted.
Photo No. 28 was taken before the final grading was complete on the outside slope of the Cell 4B dike. The
slopes of the cell dikes are intentionally over-built during construction in order to allow for final grading of the
slopes back to futly compacted soit. The fult profrte of the drke rs compacted, but the downstream stope of the
dikes are left with the over built material to provide erosion protection for the dike and to allow a medium for
vegetative growth.
4. Under the tab for Inspection Reports (Dec. 2009) it notes positive and negative changes in the
Ceil 4A LDS sump depths during the mor^h of December 2009 by a few inches. The same is
noted on the monthly summary tab for December 26, 2009. Please explain the cause of the
phenomenon of higher as well as lower readings of LDS levels during periods of non-pumping.
Also, has this problem continued?
Small variations in the sump levels when the pump is not running are the result of barometric pressure changes.
This phenomena was observed this past week in the Cell 4B leak detection sump when wind pressure on
expansion wrinkles in the top liner was apparently causing observable fluctuations in the measured level in the
leak detection sump. Because the air space volume in the geonet material is very small, minor pressure
changes on wrinkles in the top liner can quickly be transmitted to the leak detection sump. The opposite of this
affect was earlier observed in the Cell 4A leak detection system when the leak detection sump access riser
cover flange was removed, exposing the sump access riser to moderate wind. A small air bubble formed near
the top of the liner on the opposite side of the cell. When the cover was replaced, the bubble disappeared.
5. Under the tab for Settlement Monitors the last page is a drawing dated 12-28-09 titled,
Settlement Monitor Points. The map shows the locations of 17 proposed settlement monitor
kxations, which includes Settlement Monitor 21V5-S. This same map was provided to DRC
earlier by DUSA letter dated April 23, 2010. In this same letter it states that, "Subsequent to
the 2009 ATER, Settlement Monitor 2W5-S has been installed. The Settlement Monitor map
will be updated for the 2010 ATER and the monitoring data wilf be included in the report."
Please update the Settlement Monitor map with atl new Settlement Monitors which have been
instsHed.
A revised map showing the locations ofthe Settlement Monitors is attached.
ff you have any additional questions or comments, please feel free to contact me.
Yours very truly,
DENISON MINES (USA) CORP.
Jo Ann Tischler
Director, Compliance and Permitting
Letter to Mr. Rusty Lundberg
April 19, 2011
Page 3
cc: Ron F. Hochstein
Harold R. Roberts
David C. Frydenlund
Rich E. Bartlett
DavrdTurk
Photo Documentation of
Removal of Tree-Like Plants on Cell 2
Revised Map of Settlement Monitor Points
N
Legend
\—' Existing points
CELL 2
EAST
MONITOR
\—' Existing points
CELL 2
EAST
MONITOR
300
s
150 0 300 600
1
/\ Proposed points
PROPOSED
MONITOR
3-7S
SCALE IN FEET