DRC-2011-005660 - 0901a068802308f9

DENISO
MINES
4
Received
MAY 2011 Division of
Radiation Control
Denison Mines (USA) Corp.
1050 17th Street, Suite 950
Denver, CO 80265
USA
Tel: [phone]
Fax: [phone]
www.denisonmines.com
Mayl3,2011
VIA PDF AND FEDEX
Rusty Lundberg,
Co-Executive Secretary
Utah Water Quality Board
Utah Department of Environmental Quality
195 North 1950 West
P.O. Box 144850
Salt Lake City, UT 84114-4850
Re: State of Utah Ground Water Discharge Permit No. UGW370004
White Mesa Uranium MillNotice Pursuant to Part I.G.I
Dear Mr. Lundberg:
The White Mesa Mill (the "Mill") performed first quarter ("Qr') groundwater monitoring during
the period from January 10, to March 15, 2011 under the June 17, 2010 and February 15, 2011
versions of the Mill's Groundwater Discharge Permit (the "GWDP"). All analytical data needed
for comparison to the GWCLs was received during the period ending April 13, 2011.
Pursuant to Part LG.l.a) of the GWDP, (June 17, 2010 and February 15, 2011) please take notice
that the concentrations of specific constituents in the monitoring wells highlighted in yellow and
bold italics in the columns for the first quarter in the attached Table 1, exceeded their respective
GWCLs. For ease of review. Table 1 has been formatted to simplify the tracking of any
continued exceedances from one monitoring period to the next by charting ongoing monitoring
ofthe same well in the same row, and by highlighting exceedances (in color and bold italics).
Part I.G.I c) of the GWDP states "that the Permittee shall prepare and submit within 30 calendar
days to the Executive Secretary a plan and a time schedule for assessment of the sources, extent
and potential dispersion of the contamination, and an evaluation of potential remedial action to
restore and maintain groundwater quality to insure that Permit limits will not be exceeded at the
compliance monitoring point and that DMT or BAT will be reestablished." The summary below
relating to the first quarter 2011 exceedances includes, for each exceedance, a brief discussion of
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whether such a plan and schedule is required at this time in light of other actions currently being
undertaken by Denison, as determined by Utah Department of Environmental Quality (UDEQ)
Staff as stated in teleconferences with Denison on April 27 and May 2, 2011. Where applicable,
the plan and time schedule for assessment will be submitted to the Executive Secretary within 30
days of this exceedance notice.
Under the June 17, 2010 and February 15, 2011 revisions ofthe GWDP, GWCLs have been
determined on a well-by-well basis to reflect background groundwater quality, as defined by the
mean plus second standard deviation concentration, or the equivalent. Accordingly, the GWDP
requires that constituent concentrations in each monitoring well shall not exceed the GWCLs set
out in Table 2 of the GWDP. It should be noted that, because the GWCLs have been set at the
mean plus second standard deviation, or the equivalent, un-impacted groundwater would
normally be expected to exceed the GWCLs approximately 2.5% of the time. Therefore,
exceedances are expected in approximately 2.5% of all sample results, and do not necessarily
represent impacts to groundwater from Mill operations.
The following are items of note relevant to all exceedance data presented herein:
1. Nitrate + nitrite and chloride in monitoring wells at the site are the subject of an ongoing
investigation. In the December 30, 2009 Nitrate Contamination Investigation Report,
prepared by Intera, Inc., Intera has concluded that the elevated nitrate + nitrite and
chloride concentrations observed at the Mill resulted from sources unrelated to the Mill's
operations. Denison is in the process of proposing additional investigations to confirm the
source(s) of these constituents. UDEQ subsequently determined that the CIR is
incomplete, and Denison has agreed to perform an expanded investigation into potential
Mill-related and non-Mill related sources. Based on information provided by UDEQ in
teleconferences on April 27, and May 2, 2011, due to the ongoing investigation, the 30-
day plan and schedule for assessment is not required for nitrate + nitrite and chloride
exceedances at this time.
2. As discussed in previous quarterly groundwater sampling reports, the background levels
and GWCLs for pH were established based on eight or more quarters of laboratory data,
which are historically higher than field data due to effects from the evolution of carbon
dioxide, and subsequent increase in pH from field to lab. Denison's letter to the Co-
Executive Secretary of the Utah Water Quality Board dated January 31, 2011 proposed
the recalculation of the GWCLs for field pH. The proposal requests the recalculation of
the GWCLs based on a statistical analysis of actual field data, which is expected to result
in somewhat lower GWCLs for pH in most wells. Based on information provided by
UDEQ in teleconferences on April 27, and May 2, 2011, due to the current schedule to
provide recalculated GWCLs for field pH, the 30-day plan and schedule for assessment is
not required for field pH exceedances.
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1.0 Exceedances in Required Quarterly Sampling Wells
1.1 Quarterly Wells with Two Successive Exceedances
As indicated in the attached Table 1, the analytes discussed below exceeded their respective
GWCLs for two successive sampling periods during the first quarter 2011. Where applicable,
the 30-day plan and schedule for assessment described above will be submitted under separate
cover for exceedances which occurred in the first quarter of 2011 as well as previous
exceedances for which a plan has not been submitted to date. One time exceedances are noted
on Table 1, but not discussed below. Successive exceedances which occurred in previous
reporting periods are discussed in the respective Exceedance Notice for that quarter.
MW-14
• Field pH has been slightly outside (slightly lower than) the GWCL in MW-14 in the
January, February (Ql), and March sampling events. As mentioned above, GWCLs for
pH were incorrectly established and are currently under re-evaluation.
MW-26
• Chloroform in MW-26 has exceeded its GWCL for all of the monitoring periods for
2011. MW-26 is used as a pumping well for the ongoing chloroform capture program
and is expected to yield increased concentrations of chloroform.
Methylene chloride exceeded its GWCL in the February (Ql) and March monthly
sampling events. MW-26 is used as a pumping well for the ongoing chloroform capture
program and is expected to yield increased concentrations of methylene chloride.
MW-26 Note: As stated in the September 2009 Statement of Basis (page 23) in support of the
January 20, 2010 revisions to the GWDP, "[i]t should be noted that, because MW-26 is a
pumping well for chloroform removal, concentrations of all constituents in that well are subject
to potential variation over time as a result of the pumping activity. This will be taken into
account by the Executive Secretary in determining compliance for this well." Based on
information provided by UDEQ in teleconferences on April 27, and May 2, 2011, due to the
current pumping status as part of the chloroform program, the 30-day plan and schedule for
assessment is not required at this time for exceedances of chloroform and methylene chloride in
MW-26.
MW-30
• Nitrate + nitrite concentrations exceeded its GWCL in all sampling events during the first
quarter 2011.
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• Selenium concentrations exceeded its GWCL in all sampling events during the first
quarter 2011. A 30-day plan and schedule for assessment will be submitted under
separate cover within 30 days of this Exceedance Notice.
MW-31
• Nitrate + nitrite concentrations exceeded its GWCL in all sampling events during the first
quarter 2011.
1.2 Quarterly Wells with New Exceedances Reported in Ql
New exceedances for the quarterly well sampling program are listed below. The exceedances
listed will result in an accelerated sampling frequency from quarterly to monthly. It is important
to note that the wells listed below will only be sampled for those constituents which exceeded the
GWCLs during the monthly events. The wells listed below will be sampled for all constituents
listed in the GWDP during the quarterly events as that is the regularly scheduled sampling for the
quarterly wells.
• Chloride in MW-30 exceeded its GWCL in the Ql sampling event in February 2011.
• Chloride in MW-31 exceeded its GWCL in the Ql sampling event in February 2011.
• Field pH in MW-25 was slightly outside (lower than) the GWCL in the Ql sampling
event in February 2011.
2.0 Exceedances in Semiannual Sampling WeUs Accelerated to Quarterly
2.1 Semiannual Wells with Two Successive Exceedances
As indicated in the attached Table 1, the analytes discussed below exceeded their respective
GWCLs for two successive sampling periods (Q4 [2010] and Ql [2011]).
MW-3
• Field pH has been slightly outside (slightly lower than) the GWCL for both the Q4
sampling event and the Ql sampling event. As mentioned above, GWCLs for pH were
incorrectly established and are currently under re-evaluation.
• Selenium has exceeded the GWCL for both the Q4 sampling event and the Ql sampling
event.
• Fluoride has exceeded the GWCL for both the Q4 sampling event and the Ql sampling
event.
A 30-day plan and schedule for assessment will be submitted under separate cover within 30
days ofthis Exceedance Notice for the selenium and fluoride exceedances.
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MW-3A
• Field pH has been slightly outside (slightiy lower than) the GWCL for both the Q4
sampling event and the Ql sampling event. As mentioned above, GWCLs for pH were
incorrectly established and are currently under re-evaluation.
• Selenium has exceeded the GWCL for both the Q4 sampling event and the Ql sampling
event.
• Sulfate has exceeded the GWCL for both the Q4 sampling event and the Ql sampling
event.
A 30-day plan and schedule for assessment will be submitted under separate cover within 30
days ofthis Exceedance Notice for the selenium and sulfate exceedances.
MW-5
• Uranium has exceeded the GWCL for both the Q4 sampling event and the Ql sampling
event.
A 30-day plan and schedule for assessment will be submitted under separate cover within 30
days ofthis Exceedance Notice for the uranium exceedance.
MW-12
• Field pH has been slightiy outside (slightly lower than) the GWCL for both the Q4
sampling event and the Ql sampling event. As mentioned above, GWCLs for pH were
incorrectly established and are currently under re-evaluation.
• Selenium has exceeded the GWCL for both the Q4 sampling event and the Ql sampling
event.
A 30-day plan and schedule for assessment will be submitted under separate cover within 30
days ofthis Exceedance Notice for the selenium exceedance.
MW-18
• Thallium has exceeded the GWCL for both the both the Q4 sampling event and the Ql
sampling event.
A 30-day plan and schedule for assessment will be submitted under separate cover within 30
days ofthis Exceedance Notice for the thallium exceedance.
MW-23
• Field pH has been slightiy outside (slightly lower than) the GWCL for both the Q4
sampling event and the Ql sampling event. As mentioned above, GWCLs for pH were
incorrectly established and are currently under re-evaluation.
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MW-24
• Field pH has been slightly outside (slightly lower than) the GWCL for both the Q4
sampling event and the Ql sampling event. As mentioned above, GWCLs for pH were
incorrectly established and are currently under re-evaluation.
• Thallium has exceeded the GWCL for both the Q4 sampling event and the Ql sampling
event.
• Cadmium has exceeded the GWCL for both the Q4 sampling event and the Ql sampling
event.
A 30-day plan and schedule for assessment will be submitted under separate cover within 30
days of this Exceedance Notice for the thallium and cadmium exceedances.
MW-27
• Nitrate + Nitrite have exceeded the GWCL for both the Q4 sampling event and the Ql
sampling event.
• Chloride has exceeded the GWCL for both the Q4 sampling event and the Ql sampling
event.
• TDS has exceeded the GWCL for both the Q4 sampling event and the Ql sampling
event.
A 30-day plan and schedule for assessment will be submitted under separate cover within 30
days of this Exceedance Notice for the TDS exceedance.
MW-28
• Field pH has been slightly outside (slightly lower than) the GWCL for both the Q4
sampling event and the Ql sampling event. As mentioned above, GWCLs for pH were
incorrectly established and are currently under re-evaluation.
• Chloride has exceeded the GWCL for both the Q3 sampling event and the Q4 sampling
event and the Ql sampling event.
MW-32
• Field pH has been slightiy outside (slightly lower than) the GWCL for both the Q4
sampling event and the Ql sampling event. As mentioned above, GWCLs for pH were
incorrectly established and are currently under re-evaluation.
2.1 Semiannual Wells with New Exceedances Reported in Ql
New exceedances for the semi-annual well sampling program are listed below. The exceedances
listed will result in an accelerated sampling frequency from semi-annually to quarterly. It is
important to note that during the first and third quarterly events the wells listed below will only
be sampled for those constituents which exceeded the GWCLs because the first and third
quarterly events do not include the semi-annual well sampling program. The wells listed below
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will be sampled for all constituents listed in the GWDP during the second and fourth quarter
events as that is the regularly scheduled sampling for the semi-annual wells.
• Field pH in MW-29 was slightiy outside (lower than) the GWCL in the Q4 sampling
event in November 2010. As mentioned above, GWCLs for pH were incorrectiy
established and are currently under re-evaluation.
If you have any questions or require any fiirther information, please contact the undersigned.
Yours truly,
^Jo Ann Tischler
Director, Compliance and Permitting
cc: David Frydenlund
Ron Hochstein
Ryan Palmer
Harold Roberts
David Turk
Kathy Weinel
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