DRC-2010-002004 - 0901a0688016c2d6

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Denlson Mines (USA) Corp.
1050 17th Street, Suite 950
^ M M Mi J^ Denver, CO 80265
IN i^i USA DENISOI
r^ I N E S '''e' = 303 628-7798
Fax:[phone]
www.denisonmines.com
Febmary 18.2010
VIA PDF AND FEDERAL EXPRESS
Mr. Dane L. Finerfrock
Co-Executive Secretary
Utah Water Quality Board
State of Utali Department of Environmental Quality
168 North 1950 West
P.O. Box 144850
Salt Lake City, UT 84114-4850
Dear Mr. Finerfrock:
Re: Chloroform Contamination Investigation. Chloroform Concentrations Exceeding the
Groundwater Quality Standard in Monitor Well TW4-6. Submittal of a Revised Plan of
Action and Work Schedule. Confirmatory Action Letter.
Recent chloroform concentrations in monitor well TW4-6 at the White Mesa Mill (the "Mill")
have exceeded the 70 ug/1 State of Utah groundwater quality standard, requiring an adjustment to
the hydraulic containment program relating to the chloroform contamination plume at the Mill.
On December 31, 2009 Denison Mines (USA) Corp. ("Denison") submitted a plan of action and
work schedule to achieve hydraulic containment at TW4-6 as required by the Confirmatory
Action Letter dated November 9, 2009.
On Febmary 11, 2010 Division of Radiation Control ("DRC") and Denison staff had a
conference call to discuss Denison's proposed plan of action and schedule, at which time
Denison agreed to make several modifications to the plan and schedule. The conclusions
reached during that conference call were confirmed in an email dated Febmary II, 2010 from
DRC Staff to Denison.
Enclosed please find:
a) a copy of the letter report dated December 28, 2009 from Hydro Geo Chem, Inc., that
was previously submitted with Denison's December 31, 2009 plan and schedule; and
b) a letter report dated Febmary 16, 2010 from Hydro Geo Chem, Inc., that addresses
certain of the modifications to the plan and schedule discussed with DRC on Febmary 11,
2010.