DRC-2010-005306 - 0901a068801c8104

State of Utah
GARY R. HERBERT
Govemor
GREG BELL
Lieutenant Govemor
Department of
Environmental Quality
Amanda Smith
Executive Director
DIVISION OF RADIATION CONTROL
Rusty Lundberg
Director
DRC-2010-005306
September 29, 2010
Certified Mail
(Retum Receipt Requested)
Mr. Harold R. Roberts
Vice President, US Operations
Denison Mines (USA) Corp (DUSA)
1050 17'*" Street, Suite 950
Denver, CO 80265
Dear Mr. Roberts:
SUBJECT: Denison Mines (USA) Corporation (DUSA) White Mesa Mill Facility
DRC Cell 4B Construction Inspection September 21-22, 2010
Thin Sandbags Covering the Slimes Strip-Drains: Request for Information
As you are probably aware, we have some concems on the sandbag subject above. Both DUSA's
and DRC's consultants (GeoSyntec and URS) have independently agreed that slimes filtration by
the existing sandbags is not compromised by the minimum installed sandbag thickness of 1.5-
inches that has been observed in the field.
However, DRC does have a concem in this regard. It appears that the sandbags currently in-place
are now up to 50% lighter in weight than originally specified by DUSA and approved by the
DRC. Thus, these sandbags have more potential to be moved during the initial filling operations
of Cell 4B.
Therefore, to prevent sandbag movement, we request that DUSA submit for approval a proposal
with a demonstration that:
1) . Appropriate changes to the existing installed sandbags and any future sandbags to be
installed will be provided, or
2) . Appropriate provisions during initial filling operations of Cell 4B, to prevent the
movement of the subject sandbags, will be required. The approved provisions would need
to be placed in the Cell 4B BAT Monitoring, Operations and Maintenance Plan and
approved prior to use of the cell. These requirements would be in contrast to the existing
Cell 4A BAT Monitoring, Operations and Maintenance Plan, considering the lighter
sandbags in Cell 4B. These adjustments to the requirements during initial filling must
195 North 1950 West • Salt Lake City, UT
Mailing Address: P.O. Box 144850 • Salt Lake City, UT 84114-4850
Telephone [phone] • Fax [phone] • T.D.D. [phone]
www.deq.ulah.gov
Printed on 100% recycled paper
Page 2
consider effective methods for reduction in tailings flow forces applied to these sandbags
as well as concurrent rainfall events during initial filling of Cell 4B.
Per your email of September 28, 2010, you committed that DUSA would fully respond to this
request no later than 15 calendar days after receipt of this letter.
If you have any questions on the above, please contact me.
Sincerely,
David A. Rupp, P.E.
Geotechnical Services Section
DR:dr
F:\Cell 4B\Consu-\Thin Sandbags RFIl 9-20I0.doc