DRC-2010-003908 - 0901a068801a51a4

DENISO
MINES
July 12, 2010
Loren Morton
Utah Radiation Control Board
Utah Department of Environmental Quality
195 North 1950 West
P.O. Box 144810
Salt Lake City, UT 84114-4810
Denison Mines Corp.
6425 S. Highway 191, PO Box 809
Biamflng, UT 84S11
USA
Tel : [phone]
Fax : [phone]
www.denisonmines.coin
n
Dear Mr. Morton:
Re: State of Utah Ground Water Discharge Permit No. UW370004 White Mesa Uranium Mill
- QuaUty Assurance Plan and P. Goble Requests for Information Dated June 1, 2010 and
June 24,2010.
This letter summarizes Denison Mines (USA) Corp.'s ("Denison's") understanding of our telephone
conversation with the Utah Division of Radiation Control ("DRC") this moming July 12, 2010,
particularly as regards our discussion of Mr. Goble's letters of June 1 and June 24, 2010.
Item 2 of Mr. Goble's letter of June 1, 2010 asked that Denison "explain and justify how DUSA used
all commonly available well development techniques on the wells in question, including: Bailing,
surging, jetting, and overpumping." The same paragraph later states "Before the DRC can consider
approval of any variance regarding turbidity in monitoring wells, DUSA has to provide convincing
evidence that all monitoring wells at the Mill have been developed properly and all commonly [sic]
well development methods were attempted and exhausted." Mr. Goble's letter of June 24, 2010 stated
that "Before the DRC can consider any change regarding Turbidity in the DUSA QAP, DUSA must
first resolve item 2 of the June 1, 2010 Request for hiformation."
Per today's conversation regarding what the foregoing letters require for well development of White
Mesa Mill wells, Denison understands that DRC expects Denison to determine what, if any, additional
well development measures may be required.
First, Denison will review historic field parameter data for all on site wells, include groundwater,
chloroform, and nitrate wells, to sort them into the following categories, which will be used to
determine:
• Wells which consistently equilibrate to within 10% RPD, even though turbidity may exceed 5
NTU. Redevelopment of these wells will not be required.
• Wells which have consistently had turbidity results below 5 NTU, even though the results
below 5 NTU may not equilibrate within 10% RPD. Redevelopment of these wells will not be
required.
• Wells which have generally had turbidity results below 5 NTU, but do not consistently
equilibrate to within 10% RPD, and on occasion exceed 5 NTU. Denison will not redevelop
these wells at this time but will flag these wells for future consideration of redevelopment.
• Wells which have consistently had turbidity results above 5 NTU, and turbidity results which
do not consistently equilibrate to within 10% RPD. Denison will evaluate and recommend to
DRC appropriate methods of redevelopment for these wells.
Second, Denison will evaluate the four types of well development identified in Mr. Goble's letter of
June 1, 2010, as well other approaches in the literature. Based on the recommendations provided in
regulatory agency approved guidance documents and peer-reviewed literature, Denison will consider
the short and long-term effects on the well performance and monitoring program results of approaches
that have not yet been applied to monitor wells at the Mill, including overpumping and jetting.
Denison will submit for DRC review a proposal recommending and defending what additional
development methods can reasonably be applied to those wells whose performance may indicate the
need for redevelopment.
Third, Denison will also propose and justify to DRC what development methods will be applied to
new wells scheduled for installation in 2010, or later.
We would appreciate a confirmation or clarification of this summary at your earliest convenience.
Yours very truly,
)ENisoN MINES (USA) CORP.
Jo Ann Tischler
Director, Compliance and Permitting
Cc: David Frydenlund
Phil Goble
Ron Hochstein
Harold Roberts
David Turk
Kathy Weinel
DENISO
MINES