DRC-2010-005964 - 0901a068801dc537

C-2010-00596
DENISO
MIMES
November 11, 2010
Denison Mines (USA) Corp.
1050 17th Street, Suite 950
Denver, CO 80265
USA
Tel: [phone]
Fax : [phone]
www.denisonmines.com
VIA PDF AND EXPRESS DELIVERY
Rusty Lundberg, Executive Secretary
Utah Division of Radiation Control
Utah Department of Environmental Quality
195 North 1950 West
P.O. Box 144810
Salt Lake City, UT 84114-4820
Dear Mr. Lundberg:
Re: State of Utah Ground Water Discharge Permit ("GWDP") No. UGW370004 White Mesa Uranium
IVtill - Update on Findings on Cell 1 Leak Detection system ("LDS")
This letter report responds, in part, to the Utah Division of Radiation Control's September 22, 2010 Conditional
Approval and Confirmatory Action Letter regarding the White Mesa Mill (the "Mill") Cell 1 leak detection system
("LDS") and Denison Mines (USA) Corp's ("Denison's") telephone conversations with DRC on August 23,
September 15, and September 21, 2010. A separate letter which summarized Denison's inspection of the LDS
level measurement process and resolved apparent inconsistencies in Cell 1 LDS depth and liquid level
measurements, as requested in DRC's September 22, 2010 letter, was submitted to DRC on September 30,
2010.
Status of Required Actions in DRC's September 22, 2010 Letter
Item 1. Determine the root cause of the apparent discrepancies of the Estimation of Cell 1 Leakage
Rate. (Table 1) and submit written findings bv September 30. 2010 for Executive Secretarv review and
approval.
As mentioned above, the requirements in Item 1 were addressed in a letter submitted under separate cover.
Item 2. Perform a video log of the Cell 1 LDS standpipe down to the T-ioint with the slotted collection pipe and
determine the total downslope distance to the nearest 0.1 foot. If anv debris is observed within the standpipe,
this debris will be removed. If debris is observed, another video log will need to be performed after the debris is
removed to document that the standpipe is free of debris. Both video logs will be performed and submitted for
DRC review and approval bv November 1. 2010.
As required by Item 2, Denison identified a camera inspection contractor and completed the initial video log of
the Cell 1 LDS pipe prior to November 1, 2010. Identification of a contractor that was willing to perform the
scope of work took well into October, since those initially contacted were unwilling to expose their equipment to
the aggressive conditions of the Cell 1 system. The one contractor willing to perform the scope of work, RNR
N:\Cell 1 Plan and Repairs 2010\Cell 1 LDS Update report to DRC 11.11.10.doc
Letter to Rusty Lundberg - Cell 1 LDS Update Report
November 11, 2010
Page 2
Enterprises ("RNR"), was not available until late October. They completed the video logging on October 22,
2010, and video images were printed and available to Denison's corporate office after that date.
Enclosed with this letter, Denison has provided a copy in CD-ROM format of the continuous video images from
RNR's camera inspection ofthe Cell 1 LDS. Review ofthe video images provided the following information:
1. RNR's camera scan extended from the pipe entrance at the top of the cell dike to a depth along the
pipe length of 57.5 feet. The camera eye could not be extended past that depth due to the presence of
material buildup blocking part, but not all, of the pipe. By comparison, the blow tube used in LDS depth
measurements, which is narrower than the camera's probe or snaking device, can be inserted
consistently to a depth of 69.5 feet along the pipe length.
2. Several segments of older, broken blow tube are visible in the images. The topmost end of the first one
is visible at approximately 33 feet.
3. The intermittent presence of sediment or soil that does not reduce the diameter of the pipe or obstruct
the passage of the camera or the blow tube is visible beginning at 40 feet.
4. A rock or other consolidated mass that can still be bypassed by both the camera and the blow tube is
visible at approximately 52 feet.
5. Buildup of sediment or soil along the bottom half of the pipe which reduces the diameter of the pipe, but
apparently has not obstructed the camera or LDS tube, is visible from approximately 54 feet depth to
57.5 feet depth at which point the camera probe is obstructed and cannot be extended any further.
Path Forward
Based on the images, and consistent with Item 2 of DRC's September 22 letter, Denison has determined that
the LDS pipe does require maintenance to remove the tube debris, and the accumulated sediments,
precipitates, or soil material. Denison's maintenance and engineering staff are currently evaluating different
approaches for clearing the pipe; however, we are concerned about the potential effects from each of the
options under consideration.
We would like the opportunity to discuss the pros and cons of the potential approaches with DRC and receive
DRC's concurrence on a plan and schedule before implementing the selected maintenance action(s).
Therefore, we are in the process but have yet not completed the final steps under Item 2, which require that if
debris is observed, maintenance and a confirmatory video of the cleared pipe are to be submitted by November
1, 2010.
We request that DRC review the enclosed CD-ROM images and propose one or more dates when DRC
personnel are available for this discussion.
Please contact the undersigned if you have any questions or require any further information.
DENISO
MINES
Letter to Rusty Lundberg - Cell 1 LDS Update Report
November 11, 2010
Page 3
Yours very truly,
DENISON MINES (USA) CORP.
—^
Jo Ann Tischler
Director, Compliance and Permitting
cc: Rich Bartlett
David C, Frydenlund
Ron F. Hochstein
Harold R. Roberts
David E. Turk
Kathy Weinel
Enclosure: CDRom Video of Cell 1 LDS
DENISON
MINES