DRC-2011-007338 - 0901a0688026affc

DENISON^^
MINES
September 7, 2011
VIA E-MAIL AND OVERNIGHT DELIVERY
Mr. Rusty Lundberg
Utah Department of Environmental Quality
195 North 1950 West
P.O. Box 144850
Salt Lake City, UT 84114-4850
SEP
Denison Mines (USA) Corp.
105017th Street, Suite 950
Denver, CO 80265
USA
Tel : [phone]
Fax:[phone]
www.denisonmines.com
Re: Transmittal of Plan and Time Schedule under Utah
UGW370004 Part I.G.4 (d) White Mesa Mill (the "Mill")
Dear Mr. Lundberg:
Ground Water Discharge Permit
This letter transmits Denison Mines (USA) Corp.'s ("Denison's") Plan and Time Schedule pursuant to State of
Utah Groundwater Discharge Permit UGW370004 (the "Permit") Part I.G.4(d) for Violations of Part I.G.2 of the
Permit. Part I.G.2 of the Permit provides that out-of-compliance ("OOC") status exists when the concentration
of a pollutant in two consecutive samples from a compliance monitoring point exceeds a groundwater
compliance limit ("GWCL").
On August 8, 2011, Denison submitted a notice to the Executive Secretary under Part I.G.I (a) of the Permit
providing notice that the concentrations of specific constituents in groundwater monitoring wells at the Mill
exceeded their respective GWCL's for the 2 quarter of 2011 and indicating which of those constituents had
two consecutive exceedances during that quarter. This Plan and Time Schedule addresses violations of Part
I.G.2 of the Permit for the 2""^ quarter of 2011.
Please contact me if you have any questions or require any further information.
Yours very truly,
DENISON.MIN/S (USA) CORP.
ln rischler
fector Compliance and Permitting
cc: David C. Frydenlund
Harold R. Roberts
David E. Turk
K. Weinel
Central files
N:\Notices\GW plans for dual exceedances\09_07__l 1 Trnmtl GW Work Plan and Schedule Q2 2011.doc
WHITE MESA MILL
State of Utah Ground Water Discharge Permit UGW370004
Plan and Time Schedule
Under Part LG.4 (d)
For
Violations of Part I.G.2 for Constituents in the Second Quarter of 2011
Denison Mines (USA) Corp.
1050 17*^ St., Suite 950
Denver, CO 80265
September?, 2011
1. INTRODUCTION
Denison Mines (USA) Corp. ("Denison") operates the White Mesa Uranium Mill (the "Mill"),
located near Blanding Utah, under State of Utah Ground Water Discharge Permit UGW370004
(the "Permit").
This is the plan and time schedule (the "Plan") required under Part I.G.4(c) of the Permit relating
to violations of Part I.G.2 of the Permit for the 2""* quarter of 2011. Part I.G.2 of the Permit
provides that out-of-compliance status exists when the concentration of a pollutant in two
consecutive samples from a compliance monitoring point exceeds a groundwater compliance
limit ("GWCL") in Table 2 ofthe Permit.
The Permit was originally issued in March, 2005, at which time GWCLs were set on an interim
basis, based on fractions of State Ground Water Quality Standards or the equivalent, without
reference to natural background at the Mill site. The Permit also required that Denison prepare a
background groundwater quality report to evaluate all historic data for the purposes of
establishing background groundwater quality at the site and developing GWCLs under the
Permit.
As required by then Part I.H.3 of the Permit, DUSA submitted the following to the Co-Executive
Secretary (the "Executive Secretary") of the State of Utah Water Quality Board:
• A Revised Background Groundwater Quality Report: Existing Wells For Denison Mines
(USA) Corp.'s Mill Site, San Juan County, Utah, October 2007, prepared by INTERA,
Inc. (the "Existing Wells Background Report");
• A Revised Addendum: - Evaluation of Available Pre-Operational and Regional
Background Data, Background Groundwater Quality Report: Existing Wells For
Denison Mines (USA) Corp.'s Mill Site, San Juan County, Utah, November 16, 2007,
prepared by INTERA, Inc. (the "Regional Background Report"); and
• A Revised Addendum: — Background Groundwater Quality Report: New Wells For
Denison Mines (USA) Corp. 's Mill Site, San Juan County, Utah, April 30, 2008, prepared
by INTERA, Inc. (the "New Wells Background Report, and together with the Existing
Wells Background Report and the Regional Background Report, the "Background
Reports").
Based on a review of the Background Reports and other information and analyses the Executive
Secretary re-opened the Permit and modified the GWCLs to be equal to the mean concentration
plus two standard deviations or the equivalent. The modified GWCLs became effective on
January 20, 2010.
Section I.G.4(c) of the permit requires that DUSA submit a written plan and time schedule, for
Executive Secretary approval, including, but not limited to:
(i) submittal of a written assessment of the source(s);
(ii) submittal of a written evaluation of the extent and potential dispersion of said
groundwater contamination; and
(iii) submittal of a written evaluation of any and all potential remedial action to restore and
maintain ground water quality at the facility, for the point of compliance wells and
contaminants in question, to ensure that: 1) shallow groundwater quality at the facility
will be restored and 2) the contaminant concentrations in said point of compliance wells
will be returned to and maintained in compliance with their respective GWCLs.
On August 8, 2011 Denison submitted a notice (the "2""^ Quarter 2011 Exceedance Notice") to
the Executive Secretary under Part I.G. 1(a) of the Permit providing notice that the concentrations
of specific constituents in the monitoring wells at the Mill exceeded their respective GWCLs for
the 2"^ quarter of 2011 and indicating which of those constituents had two consecutive
exceedances as of that quarter.
This Plan covers the constituents in violation of Part I.G.2 of the Permit that were identified as
being in violation in the 2""^ Quarter 2011 Exceedance Notice for the first time beginning in the
2""* quarter of 2011 (the "Q2 2011 Consecutive Exceedances").
2. CONSTITUENTS AND WELLS SUBJECT TO THIS PLAN
The following Q2 2011 Consecutive Exceedances have been identified as being in out-of-
compliance status under Part I.G.2 of the Permit in the l""^ Quarter 2011 Exceedance Notice
Table 1
Constituents and Wells Subject to this Plan
Constituent Monitoring Event POC Well GWCL Result
TDS Qtr 2011 (2/15/2011)
2"'*Qtr, 2011 (4/6/2010)
MW-18 3198.77 mg/L 3250 mg/L
3250 mg/L
Uranium
May 2011 (5/11/2011)
June 2011 (6/20/2011)
MW-25 6.5 ng/L 6.72 ng/L
7.06 ng/L
Uranium 1''Qtr 2011 (2/15/2011)
2"" Qtr 2011 (4/12/2011)*
2"*^ Qtr 2011 (6/7/2011)
MW-35 7.5 ng/L 12.7 ng/L
19.9 ng/L
21.7 ng/L
Manganese
1''Qtr 2011 (2/15/2011)
2"*^ Qtr 2011 (4/12/2011)*
2"*^ Qtr 2011 (6/7/2011)
MW-35 200 ng/L 248 ng/L
580 ng/L
369 ng/L
* An additional sample was collected in this well during the second quarter 2011 as described in the Q2 2011
Groundwater Report submitted under separate cover on August 31, 2011. Both results are included.
It should be noted that the Notice of Violation and Compliance Order, Docket No. UGWll-02
(the "Notice"), dated May 9, 2011 and the l""^ Quarter 2011 Exceedance Notice identify a
number of wells with consecutive exceedances of Nitrate -h Nitrite and/or Chloride (MW-26,
MW-27, MW-28, MW-30 and MW-31), Chloroform and Dichloromethane (MW-26), and pH
(less than the respective GWCLs for pH in a number of wells). However, none of those
constituents are included in this Plan, for the reasons stated in the Notice. That is. Chloroform
and Dichloromethane are associated with the Chloroform Plume, and the August 23, 1999 DRC
Notice of Violation and Groundwater Corrective action Order. Nitrate -h Nitrite and Chloride are
associated with the Nitrate/Chloride plume, and are currently being investigated by Denison
pursuant to a January 28, 2009 Stipulated Consent Agreement. Denison notified DRC in a letter
dated February 1, 2011 that explained the existing GWCLs for groundwater pH are in error due
to reliance on historical laboratory values instead of field measurements, and proposed a plan to
submit revised descriptive statistics for Field pH to be used as revised GWCLs.
It should also be noted that a number of wells had exceedances of GWCLs in the 2"^ quarter
2011 that also had consecutive exceedances in previous quarters (MW-3, MW-11, MW-18
(thallium), MW-24, MW-26, MW-27, and MW-30. This report covers only the Q2 2011
Consecutive Exceedances; that is, those exceedances which were consecutive beginning in the
2"^ quarter 2011. Consecutive exceedances which occurred in previous reporting periods are
discussed in the previous Plan and Time Schedule Under Part I.G.4 (d), submitted on June 13,
2011.
3. CATEGORIES FOR ANALYSIS
The constituents and wells listed in Table 1 can be separated into a number of different
categories, as follows:
3.1. Constituents Potentially Impacted bv Decreasing pH Trends Across the Site
Denison has observed a decreasing trend in pH in a number of monitoring wells across the Mill
site. See the discussion in Section 2.5.6 of the New Wells Background Report, where INTERA
noted that as at the date of that report there were statistically significant decreasing trends in pH
in MW-25. INTERA also noted that, while not statistically significant, on a review of the pH
time plots in all existing wells, there appeared to be a general decreasing trend in pH in all wells.
The mobility in groundwater of the following Q2 2011 Consecutive Exceedance constituent is
sensitive to decreases in pH:
Table 2
Constituents Potentially Impacted by Decreasing Trends in pH
Constituent Well
Uranium MW-25
3.2. Newly Installed Wells with Interim GWCLs
MW-35 was installed in August/September 2010 as required by the Permit, and sampling
commenced in 4^^ quarter 2010. As required by Part I.H.5 c) of the Permit, after the completion
of eight consecutive quarters of groundwater sampling and analysis, Denison will submit a
background report for Executive Secretary approval. As an interim measure, GWCLs have been
set by the Executive Secretary at one-quarter of the State Groundwater Quality Standards
(GWQSs). Manganese and uranium exceeded the interim GWCLs in MW-35. However, since
background has not been established in MW-35, the exceedances of these interim GWCLs do not
represent exceedances of background values.
3.3. Other Constituents and Wells
The following Q2 2011 Consecutive Exceedance constituent does not fall within one of the
previous two categories:
Table 3
Other Constituents
Constituent Well
TDS MW-18
TDS in MW-18 has been identified as having a rising trend, although it was not statistically
significant at the time of the publication of the Background Reports. However, MW-18 was
identified in the Background Reports as having a statistically significant rising trend in sulfate,
which is a component of TDS. MW-18 was also reviewed, and determined not to have been
impacted by Mill activities, in the study entitled Summary of Work Completed, Data Results,
Interpretations and Recommendations For the July 2007 Sampling Event at the Denison Mines,
USA, White Mesa Uranium Mill Near Blanding, Utah, prepared by T. Grant Hurst and D. Kip
Solomon, Department of Geology and Geophysics, University of Utah, May 2008 (the
"University of Utah Study"). Further, MW-18 is located far upgradient of the Mill facility.
4. PLAN
4.1. General
This Plan is a plan and 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 assure that Permit limits will not be exceeded at the compliance
monitoring point and that, to the extent applicable, discharge minimization technology and best
available technology will be reestablished.
Given the recent analyses in the Background Reports and other recent analyses and
investigations at the site, Denison believes that all of the Q2 2011 Consecutive Exceedances,
other than the exceedances in MW-35, are likely due to background influences (including a
natural decreasing trend in pH across the site and other factors). For MW-35, background has
not yet been set, so the exceedance of the interim GWCLs in MW-35 is not unexpected, and does
not represent exceedances of natural background values. With respect to MW-18, it is far
upgradient of the Mill site and could not have been impacted by Mill activities. Therefore,
Denison does not propose to perform any further assessments relating to the TDS exceedances at
MW-18. It is proposed that accelerated monitoring for TDS continue at MW-18 while Denison
prepares, and the Executive Secretary evaluates, an application for a revised GWCL for TDS in
that well.
The first step in the analysis will therefore be to perform an assessment of the potential sources
for the uranium in MW-25 to determine whether the exceedances are due to background
influences or Mill activities. If the exceedances are determined to be due to background
influences then it will not be necessary to perform any further evaluations on the extent and
potential dispersion of the contamination or to perform an evaluation of potential remedial
actions. Monitoring will continue, and if appropriate a revised GWCL will be proposed to
reflect changes in background conditions at the site.
However, if the uranium exceedances in MW-25 are determined to be caused by Mill activities,
then Denison will proceed to the next step and will consider the extent and potential dispersion
of the contamination, and/or will perform an evaluation of potential remedial actions to restore
and maintain groundwater quality to insure that Permit limits will not be exceeded at the
applicable point of compliance.
This two-step approach is necessary, because, in light of the varied background conditions at the
site and previously identified background trends, it cannot be assumed that consecutive
exceedances of any constituent in a well represents contamination that has been introduced to the
groundwater. It is first necessary to establish if the exceedance represents background influences
or not.
4.2. Assessment for each Category
The approach and scope of review for each of the different categories described above, is
described in more detail below.
4.2.1. Constituents Potentially Impacted by Decreasing Trends in pH across the Site.
As mentioned above, Denison has observed a decreasing trend in pH in a number of monitoring
wells across the Mill site, including MW-25. The mobility in groundwater of uranium is
sensitive to decreases in pH.
The primary focus of the source assessment for uranium in MW-25, listed in Table 2 above, will
be two-fold. First, Denison will determine whether or not there is any new information that
would suggest that the previous analysis conducted in the Background Reports, on the basis of
which the GWCL for uranium in that well was set, has changed since the date of the Background
Reports. This analysis will include the following:
(i) A geochemical analysis that will evaluate the behavior of all of the constituents in MW-
25 to determine if there are any changes in the behavior of indicator constituents, such
as Chloride, Sulfate, Fluoride and Uranium since the date of the Background Reports
that may suggest a change in the behavior of that well since the date of the Background
Reports; and
(ii) A mass balance analysis that will evaluate the observed concentrations in light of the
concentrations in Mill tailings and the presence or absence of any mounding at the
location of MW-25.
Second, a pH analysis will be performed that will:
(iii) Review the behavior of pH in MW-25 to determine if there has been a significant
decrease in pH in the well; and
(iv) Evaluate the expected impact from any such decrease in pH on the concentration of
uranium in the well, based on currently available information.
The foregoing analyses (both steps) will be included in the Source Assessment Report.
If no significant changes are identified over the analysis performed to date for uranium in MW-
25, other than what would be expected from decreasing trends in pH, then Denison will propose
changes to the GWCL for uranium in that well to better reflect background concentrations at the
site.
If significant changes are identified that cannot be attributed to changes in pH or other natural
phenomena, then Denison will propose to the Executive Secretary further analysis that may be
required in order to identify the source and the extent and potential dispersion of the
contamination, and/or potential remedial actions, including the potential application for alternate
corrective action concentration limits under UAC R317-6-6.15(G).
4.2.2 Newly Installed Wells with Interim GWCLs
As previously noted, the GWCLs for MW-35 have been set at one-quarter of the respective
GWQSs, pending determination of background for the well, and are not based on eight quarters
of data from that well. A background report for MW-35 will be completed after the collection of
eight quarters of data. In the interim, MW-35 will be sampled monthly for those constituents
which exceeded the interim GWCLs. No other action is planned for MW-35 until completion of
the background report.
4.2.3 Other Constituents and Wells
Table 3 sets out a constituent, TDS in MW-18, that does not fall within the other categories
considered in the above Sections.
MW-18 is far upgradient of the Mill site, and could not have been impacted by Mill activities.
Statistically significant rising trends in some constituents in MW-18, such as sulfate, which is a
component of TDS, have been observed in the Background Reports as being consistent with
natural background values. MW-18 was also analyzed in the University of Utah Study and
determined not to have been influenced by Mill activities. Therefore, Denison believes that the
increases in TDS concentrations in that well are also due to natural background influences and
have not been caused or contributed to by Mill activities. Therefore, Denison proposes to
continue accelerated monitoring of TDS in MW-18, while it is preparing an application for a
revised GWCL for TDS in MW-18, which reflects these natural changes in background.
As mentioned in Denison's June 13, 2011 response to the Notice, the United States
Environmental Protection Agency ("EPA") has recognized the need to update compliance limits
periodically to reflect changes to background conditions.
In 2009 guidance, EPA states:
"We recommend that other reviews of background also take place periodically.
These include the following situations:
• When periodically updating background, say every 1-2 years
• When performing a 5-10 year permit review
During these reviews, all observations designated as background should be evaluated
to ensure that they still adequately reflect current natural or baseline groundwater
conditions. In particular, the background samples should be investigated for
apparent trends or outliers. Statistical outliers may need to be removed, especially if
an error or discrepancy can be identified, so that subsequent compliance tests can be
improved. If trends are indicated, a change in the statistical method or approach may
be warranted."
and
"Site-wide changes in the underlying aquifer should be identifiable as similar trends
in both upgradient and compliance wells. In this case, it might be possible to remove
a common trend from both the background and compliance point wells and to
perform interwell testing on the trend residuals."
(EPA 530/R-09-007, March 2009, Statistical Analysis Of Groundwater Monitoring Data At
RCRA Facilities Unified Guidance, Environmental Protection Agency, Office Of Resource
Conservation And Recovery.)
In that Guidance, EPA further states:
"5.3.4 UPDATING WHEN TRENDS ARE APPARENT
An increasing or decreasing trend may be apparent between the existing
background and the newer set of candidate background values, either using a time
series plot or applying Chapter 17 trend analyses. Should such trend data be
added to the existing background sample? Most detection monitoring tests
assume that background is stationary over time, with no discernible trends or
seasonal variation. A mild trend will probably make very little difference,
especially if a Student-f or Wilcoxon rank-sum test between the existing and
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candidate background data sets is non-significant. More severe or continuing
trends are likely to be flagged as SSIs by formal intrawell prediction limit or
control chart tests.
With interwell tests, a stronger trend in the common upgradient background may
signify a change in natural groundwater quality across the aquifer or an
incomplete characterization of the full range of background variation. If a change
is evident, it may be necessary to delete some of the earlier background values
from the updated background sample, so as to ensure that compliance testing is
based on current groundwater conditions and not on outdated measures of
groundwater quality."
4.3. Experts Reports to be Prepared
The Source Assessment Report will detail the results of all of the analysis to be performed and
the conclusions to be drawn from such analyses, including any proposed revisions to existing
GWCLs. The Source Assessment Report will also identify any further studies that the analysis
indicates should be performed, and will propose, for Executive Secretary review and approval, a
plan and schedule for completion of any such additional studies.
If further analysis is required after completion of the Source Assessment Report, Denison and the
Executive Secretary will agree on the scope of that analysis, based on the findings in the Source
Assessment Report, including any further reports that will need to be prepared.
5. TIME SCHEDULE
The Source Assessment Report will be submitted to the Executive Secretary within 60 days after
approval of this Plan. The Source Assessment Report contemplated by this submission, may be
combined with the Source Assessment Report required by the previous Plan and Schedule dated
June 13,2011.
Any further studies that are identified in the Source Assessment Report or otherwise identified
by the Executive Secretary as being required in order to fulfill the requirements of Part I.G.4(c)
of the Permit, will be prepared and submitted by Denison in accordance with a schedule to be
approved by the Executive Secretary.
6. CONCLUSION
Given the varied background groundwater quality at the site, previously identified rising trends
in some wells and other factors, it cannot be assumed that consecutive exceedances of a
constituent in a monitoring well means that contamination has been introduced to groundwater in
that well.
With respect to the Q2 2011 Consecutive Exceedances observed at MW-35, background has not
yet been set for that well. The exceedances therefore do not represent exceedances of natural
background at the site. With respect to MW-18, which is far upgradient of the Mill site, the Q2
2011 Consecutive Exceedance of TDS should be considered to represent natural variation in
background, without further assessment. Rising trends in other constituents, including sulfate,
which is a component of TDS, have already been analyzed in the Background Reports and
University of Utah Study, and determined to be the result of natural background influences.
With respect to the Q2 2001 Consecutive Exceedances of uranium in MW-25, the exceedances
may very well be the result of background influences. The approach in this Plan therefore is to
first determine if the recent exceedances of uranium in MW-25 are the result of background
influences. If they are determined to be the result of background influences, then no remedial
actions are required. If, however, they are determined to not be the result of natural background
influences, then further analyses will be required.
Background at the Mill site was recently thoroughly studied in the Background Reports and in
the University of Utah Study. Both the Background Reports and the University of Utah Study
concluded that groundwater at the site has not been impacted by Mill operations. Both of those
studies also acknowledged that there are natural influences at play at the site that have given rise
to increasing water trends and general variability of background groundwater at the site.
It is not practicable to redo those studies each time a monitoring well shows consecutive
exceedances, particularly where the exceedances are consistent with those recent analyses. The
focus should therefore be on identifying any changes in the circumstances identified in those
studies.
Based on the information available at this time, Denison believes that the exceedances observed
are the result of natural influences and reflect the need to adjust some of the GWCLs for the site.
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