DRC-2011-007570 - 0901a0688028b55b

(11/15/2011) Phillip Goble - DUSA Proposed Correction of GWC for pH Page 1
From:
To:
CC:
Date:
Subject:
Jo Ann,
Phillip Goble
Tischler, Jo Ann
Frydenlund, David; Lundberg, Rusty; Mortoni Loren; Roberts, Harold
2/14/2011,6:44 AM
DUSA Proposed Correction of GWCLS for pH
DUSA submitted a letter dated February 1, 2011 proposing a plan to correct the GWCLs for pH for the on-site monitoring wells.
DUSA has previously stated that the data used to calculate a GWCLjfor Field pH in the Background Report was actually Lab pH and
not Field pH. [
1 . •
DUSA states it will base the revised GWCLs for pH on Field pH collected in monitoring events since 2005 and will foljow the
previous approved Flowchart to determine the pH GWCLs. DUSA plans to submit the revised Field pH GWCLs by ttie end of the
2™* quarter of 2011. j
I . • •
This plan is satisfactory to the DRC; therefore, the DRC will look for the report the end of the 2nd Quarter of 2011 or by June 30,
2011.
If you have any questions please let me know.
Phil
Denison Mines (USA) Corp.
1050 17th Street, Suite 950
Denver, CO 80265
USA
Tel : 303 62&7798
Fax : [phone]
www.denisonmines.com
June 30, 201 1
VlA 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 84114-4854
Re: State of Utah Groundwater Discharge Permit ("GWDP) No. UGW370004
Request for Extension of Submittal Date for Report on Proposed Correction of Groundwater
Compliance Limits ("GWCL's') for pH
Dear Mr. Lundberg:
Denison is providing this letter as requested by Loren Morton of the Utah Division of Radiation Control
('DRC) during a telephone discussion on June 28,2011 regarding ongoing exceedances of groundwater
control limits ("GWCLs') for pH, and the need for revision of GWCLs, in the tA/hite Mesa Mill's groundwater
monitoring program under the Mill's G\NDP.
1. Facts and Background lnformation
The currently approved version of the GWDP in Part l.C. Table 2, provides, for each well in the White Mesa
Mill's (the "Mill's') point of compliance program, a range of pH values to serve as its respective GWCL. The
current GWCLs are based on the evaluation reported in the Revised Background Groundwater Quqlity Report:
Existing Wells For Denison Mines (USA) Corp.'s Mill Site, San Juan County, Utah, October 20O7, piepared by
INTERA, lnc. and the 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 INTEM, lnc. (together the
"Background Study Reports). All pH data used in the Background Study Reports were produced by the Mill's
off-site contract analytical laboratory. That is, the GWCLs were based on laboratory data and were not
developed from background field data measured atthe sampling location.
Denison Mines (USA) Corp.'s ("Denison's') letter to Utah Division of Radiation Control on February 1,2011
proposed that Denison would submit a report on or before June 30, 2011 that would evaluate the proper
(field) pH data and would propose a corrected set of GWCLs for pH. DRC indicated that this approach was
satisfactory in DRC's email of February 14,20'11. As a result of performance of the statistical evaluation,
Denison has determined that an extension to the June 30, 2011 date for submittal of the report is required
2. Actions Taken to Date
Denison completed this evaluation in anticipation of providing a report including revised GWCLs by June 30,
2011, a date proposed by Denison in the February 1,2011 letter. As stated in Denison's February 1,2011
letter, the proposed revised GWCLs for pH were to be determined in accordance with the logic flow
diagram/decision tree (the "Logic Flow Diagram') set out in the Background Study Reports, which was used
to set all of the other GWCLs at the site. Following the statistical evaluation of pH data by Denison's
geochemical consultant, INTERA, lnc., Denison compared the Mill's most recent groundwater pH data from
the second quarter of 2011 , including accelerated sampling results as recent as June 2011, and noted that a//
of the June 2011 groundwater results, and many of the other results from the second quarter, were already
N.\Field pH GV1CL study\06 30 11 ltr to R Lundberg pH extension.doc
Letter to Mr. Rusty Lundberg
June 30, 201 1
Page 2
outside the revised GWCLs to be proposed in the June 30,2011 letter, based on the Logic Flow Diagram.
INTERA further noted that the historical trend of decreasing pH, which was addressed in the Background
Study Reports, appears to be present in nearly all wells throughout the Mill site area, including upgradient,
downgradient, and side-gradient wells in the groundwater, nitrate and chloroform monitoring programs.
It appears that this site-wide phenomenon of decreasing pH trends may render the Logic Flow Diagram
inappropriate for setting GWCLs for pH at the site. As a result of this finding, Denison has initiated a number
of investigations and is in the process of identi[ting other investigations, for which additional time would be
needed for completion of studies and publication of findings. The investigations identified to date include:
. Tracking of historical trends in pH levels system-wide to determine if the trends are linked to any
temporal events, such as changes in monitoring methods, equipment or frequency;o Comparison of wells with depressed pH to conclusions in the University of Utah study regarding well
water age and source at the Mill site;. Performing a literature search to determine if this type of phenomenon has been identified elsewhere
and if so what the causes were determined to be;. Evaluation of common factors among site-wide groundwater wells,. Investigation of sources of system-wide pH reduction, such as oxidation of pyritic bedrock, discussed
in more detail below; and. Evaluation of climatic changes, such as draught, that could lead to increases in natural oxidation in
the perched aquifer.
3. Root Cause
At the time of the February '1, 2011 letter Denison considered the root cause to be the use of lab pH to
establish GWCLS, while, per the GWDP, the parameter to be monitored and reported is field pH. After further
statistical analysis, however, we have concluded that there appears to be a more fundamental systenrwide
root cause or causes as discussed below.
Based on a review of well information available to date, the following factors are common to the Mill site wells:
1. Perwelldrilling logs available to date, a very high percentage of wells drilled atthe \A/hite Mesa Mill
and background locations appear to be drilled in formations containing pyrite (iron sulfide) in contact
with the groundwater interface.2. All wells, including all wells with ongoing reduction in pH, have been subject to barometric connection
with atmospheric oxygen.3. Allwells, including wells with ongoing reduction in pH, have been subject to significant and repeated
stresses driving mass transport of oxygen into the pyritic portions of the formation such as surging,
bailing, and over-pumping for redevelopment, ongoing pumping during routine monitoring, (and, for
some wells, more frequent pumping stresses due to accelerated monitoring).4. Chloroform pumping wells have also been subjected to the additional stresses of on-and-off pumping
cycles for chloroform capture pumping.
Literature and textbook sources extensively discuss the phenomenon of acid solution formation, pH
depression, and associated sulfate concentration elevation from pyrite exposure to oxygen and water. This
phenomenon, occurring system-wide throughout the White Mesa Mill site, could be the primary root cause of
the pH reduction ongoing in the Mill groundwater data.
Denison is additionally evaluating the effects of drought, regional recharge water pH, and field instrumentation
as potential contributors to the pH depression phenomenon, and is also in the process of identiffing other
potential causes of the decreasing trends in pH.
Moreover, Denison has identified the issue of decreasing trends in pH in the Background Study Reports, which
explain why the use of background mean + 2 sigma for statistical establishment of GWCLs in wells with
oEililr$$Jldd
fi,llHE$
Letter to Mr. Rusty Lundberg
June 30, 201 1
Page 3
statistically significant trends in background data is inappropriate and untenable, and that a modified approach
to establishment of GWCLs should be considered. Recent EPA Guidance (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) also recommends that trends may signify
a change in natural groundwater quality across an aquifer or incomplete characterization of the full range of
background variation, and that background should be sampled throughout the life of the facility, periodically
reviewed, and revised as necessary. lt may therefore be necessary to develop a revised Logic Flow Diagram
for developing (and periodically resetting) GWCLs for constituents such as pH that may experience natural
trends in concentrations.
4. Proposed Actions and Path Forward
Denison requests that the proposed submittal date of June 30, 2011 for the pH GWCL report be extended.
Denison proposes to submit to DRC by August 31, 2011 a Work Plan and Schedule to complete the
investigations identified in Section 3, above. Denison also requests the opportunity for a meeting with DRC in
July or August 2011 , to discuss Denison's findings to date and to agree upon any further investigations to be
completed, as well as to agree upon the steps and milestone dates to be incorporated in the Work Plan and
Schedule.
5. Affirmative Defense
Denison believes that the affirmative defense in Part l.G.3.c) of the Permit should be applicable to this
incident, for the following reasons:
a) Notification
By virtue of the ongoing discussions between DRC and Denison prior to February 1,2011, the written request
given to DRC in Denison's letter of February 1,2011, DRC's acceptance of the need for revised GWCLs as
indicated in DRC's email of February 14,2U1, Denison's discussion with DRC on June 28,2011, and this
letter, Denison has provided sufficient notification to DRC of Denison's need to evaluate the natural
phenomena affecting groundwater pH at the Mill site.
b) Failure was not lntentional or Caused by the Permiftee's Negligence
Denison does not believe there is a failure under the GWDP. The current GWCLs for pH were incorrectly set,
based on laboratory pH, and are inappropriate. There are therefore cunently no properly set GWCLs for pH
at the site. Denison is in the process of remedying this by proposing new GWCLs for field pH. However,
statistical analysis has demonstrated that the method set out in the Background Study Reports may not be
appropriate for setting GWCLs for field pH, due to the site-wide decreasing trends in pH. The ongoing
systern-wide reduction in pH was not caused by Denison's negligence, either in action or in failure to act. As
discussed above, Denison believes that the ongoing reduction in pH and resultant inability to meet existing or
proposed new GWCLs for pH, are the result of natural phenomena wholly out of Denison's control, such as
stresses introduced by the extensive groundwater disturbances required by the current GWDP and
monitoring program as it is cunently designed.
c) The Permittee has Taken Adequate Measures to Meet Permit Conditions
Denison has provided all the notifications and discussion identified in ltem 2 and the ongoing actions described
in ltem 3 above.
d) Denison has taken adequate measures to meet Permit conditions in a timely manner.
Denison has raised the issue and is in the process of proposing appropriate GWCLs for pH.
e) The Provisions of UCA 19-5-107 Have Not Been Violated
DENrsolrDddIrfiHt5
Letter to Mr. Rusty
June 30, 201 1
Page 4
The provisions of Utah Code 19-5-107 have not been violated. There has been no discharge of a pollutant
into waters of the state. Denison has not caused pollution which constitutes a menace to public health and
welfare, or is harmfulto wildlife, fish or aquatic life, or impairs domestic, agricultural, industrial, recreational, or
other beneficial uses of water, nor has Denison placed or caused to be placed any waste in a location where
there is probable cause to believe it will cause pollution.
Please contact me if you have any questions or require any further information.
Yours very truly,
Derusoru Mrrues (USA) CoRp.
a
Lundberg
*fu- de;J*r^*,
Jo Ann Tischler
Director, Compliance and Permitting
cc: David C. Frydenlund
Harold R. Roberts
David E. Turk
Katherine A. Weinel
orlrHo#)dd
IttllrlEg
rzTBc L ot z
Thomas Rushing ii - DUSA January 20, 2OL2 Letter Re: pH Study
From:
To:
Date:
Subject:
CC:
Thomas Rushing ii
dfrydenlu [e-mail]
2127120t2I:27 Pttl
DUSA January 20, 20t2 Letter Re: pH Study
Goble, Phillip; Lundberg, Rusty; Tischler, Jo Ann
Dave,
DRC has started review of the Denison Mines (USA) Corp. (DUSA) January 70,20L2 Letter regarding the Plan
and Time Schedule (Required by Part I.G.4.d. of Groundwater Permit UGW370004) to investigate groundwater
monitoring wells in out-of-compliance (OOC) status for pH at the White Mesa Uranium Mill. The
affected groundwater monitoring (MW) wells currently include: MW-3, MW-3A, MW-12, MW-14, MW-18, MW-19,
MW-23, MW-24, MW-25, MW-26, MW-28, MW-29, MW-30, MW-31, and MW-32. Additionally, Monitoring Well
MW-27 is in Probable OOC status for pH.
Per conference calls held on December 5 and 19, 2011 between DRC staff and DUSA staff it was discussed that
in order for DUSA to substantiate the claim that pH exceedences (and decreasing pH trends) in groundwater are
due to oxygenation of groundwater at the affected wells (caused by DUSA well development and overpumping
activities), and subsequent geochemical reactions from the dissolution of iron pyrite, DUSA will be required to
quantify the amount of iron pyrite available for dissolution in the aquifer mineral matrix (sample collection and
laboratory analysis).
Note that well development and overpumping would introduce oxygen in a limited area surrounding the
monitoring well screened interual. Thus, iron pyrite available for dissolution needs to be verified to be within
close proximity to the monitoring well in question and within elevations of the screened interval for the affected
well in order to substantiate the hypothesized geochemical process. DRC disagrees with the Hydro Geo Chem
(January 20, 20LZ document) statement that " pyrite can be considered ubiquitous throughout the perched
zone." Based on DRC reviews of lithological logs it appears that visible iron pyrite is logged only at discreet
intervals and rarely as a notable occurrence.
DRC discussed that in order to provide this confirmation DUSA would need to provide laboratory analysis
(quantified iron pyrite results) of samples from new borings in close proximity to each of the affected monitoring
wells. It was DRC's understanding, based on further conversation with DUSA, that there were potentially
existing borings from the wells in question, and that new borings may not be necessary at some of the wells.
DRC understood that DUSA planned to inventory available core for the affected wells.
However, per the January 20, 20tZ report by Hydro Geo Chem. Inc. Table 3., it appears that only one intact
core is planned to be submitted for laboratory analysis from well No. TW4-22 which is not one of the affected
monitoring wells. Additionally, of the other wells where "cuttings" are to be submitted for laboratory analysis,
none of the twelve wells listed in Table 3. are affected wells. DRC also notes that Table 2 of the Hydro Geo
Chem Report includes 21 samples of well cuttings which will be used for visual examination for pyrite, of these
21 samples only two (MW-30 and MW-31) are from affected wells. It was also noted that there is no
description of intervals where the cuttings will be collected (e.9. copies of the lithologic field logs & planned
sampling interuals) to verify that the planned cuttings are at depths which correlate with the screened interval.
Therefore, per DRC review of the January 20,20LZ DUSA submission it appears that no existing cores were
found which can be used to verify the existence of iron pyrite within the formation in proximity of the affected
wells, and that new borings will be required at the affected wells,
We would like to set up a conference call to discuss this issue. Phil and I are available for a call between 3:00
g:'l^.//r\.\T\^^rr-^^-+- ^-I Q^++:--^\+*,.^Li--\T ^^^I Q^tti--^\'f^--\\afr-*..,:^^\/EzlDQ,{h?Ef\ af\1 l'rf\1a
. riTEY a.Jr z
P.M. - 4:30 P.M. today (2127), between 1:00 P.M. - 4:30 P.M. tomorrow (2128) or any time on Wend. (2129).
Please let us know if you are available during one of these times or an alternate time. Thanks.
Tom
Tom Rushing, P.G.
Utah Division of Radiatbn Control
(801) s36-0080
(801) s33-4097 fax
[e-mail]
f:l^.//fr.\T\^arr*aaro ^-l C^++:--.\+-.^Li--\T ^^^l S^i+:--^\'r^h6\\aT)^*..,:-^\/E/E!Q/T\?Er\ nlall''ril',