DRC-2012-001715 - 0901a068802f9734

State of Utah
GARY R HERBERT
Governor
GREG BELL
Lieutenant Governor
July 12, 2012
•001715
Department of
Environmental Quality
Amanda Smith
Executive Director
DIVISION OF RADLVTION CONTROL
Rusty Lundberg
Director
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RE 7/12/12, stipulated consent agreement/ tr
David C Frydenlund
Vice President & General Counsel
Denison Mines (USA) Corp (DUSA)
105017th ST STE 950
Denver CO 80265
PS Form 3«00. August 2006 David Frydenlund, Vice President, Regulatory Affairs aim vJo
Denison Mines (USA) Corp.
1050 17*^ Street
Suite 950
Denver, CO 80265
Subject: Stipulated Consent Agreement, Docket No UGW 12-03
Dear Mr Frydenlund
A copy of the duly executed Stipulated Consent Agreement, Docket No UGW 12-03 (SCA) is
enclosed The SCA is dated and effective as of July 12, 2012
Please contact Tom Rushing at [phone] if you have any questions regarding this matter
Sincerely,
See Reverse for Instructions
Rusty Lundberg
Director
Enclosure Stipulated Consent Agreement Docket No UGW 12-03
RLTRtr
F \DUSA\OOC Plan and Time Schedule and pH\SCA\SCA UGW12-03 Cover Ltr docx
195 North 1950 West • Salt Lake City, UT
Mailing Address P O Box 144850 • Salt Lake City, UT 84114-4850
Telephone [phone] • Fax [phone] 'TDD [phone]
www deq utah gov
Pnnted on 100% recycled paper
UTAH DEPARTMENT OF ENVIRONMENTAL QUALITY
IN THE MATTER OF
DENISON MINES (USA) CORF.
1050 17*" Street, SUITE 950
DENVER, COLORADO 80265
STIPULATED CONSENT AGREEMENT
DOCKET No. UGW12-03
A. STATUTORY AUTHORITY
This STIPULATION AND CONSENT AGREEMENT (AGREEMENT) is between Denison
Mines (USA) Corp. (DUSA) and the Director ofthe Utah Division of Radiation Control'
(DIRECTOR) under the Utah Water Quality Act, Utah Code Ann (UCA) §§ 19-5-101 to 19-5-
124 (the ACT), including sections 19-5-104, -106, -111 and -115 This AGREEMENT is also
executed in accordance with the Utah Administrative Procedures Act, Utah Code Ann. §§ 63G4-
101 to -601 and Administrative Procedure Rules, Utah Admin Code R305-6.
Under the Water Quality Act, Utah Code Ann Title 19, Chapter 5, "Director" for purposes of
groundwater quality at a facility licensed by and under the jurisdiction ofthe Division of
Radiation Control, means the Director of the Division of Radiation Control Utah Code Ann. §
19-5-102(6).
The DIRECTOR may enforce rules made by the Water Quality Board in accordance with Utah
Code Ann. § 19-5-106(2)(d)
B. APPLICABLE STATUTORY AND REGULATORY PROVISIONS
1. Utah Code Ann § 19-5-107(1 )(a) requires that-
"Except as provided in this chapter or rules made under it, it is unlawful for any person to
discharge a pollutant into waters of the state or to cause pollution which constitutes a
menace to public health and welfare, or is harmful to wildlife, fish or aquatic life, or
impairs domestic, agricultural, industrial, recreational, or other beneficial uses of water,
or to place or cause to be placed any wastes in a location where there is probable cause to
believe it will cause pollution."
2. DUSA was issued Utah Ground Water Quality Discharge Permit No UGW370004
(Permit) on March 8,2005. Said Permit was modified by the DIRECTOR on March 17,
2008, January 20,2010, June 17,2010, February 15, 2011 and was last modified on July
14,2011.
3. The DIRECTOR issued DUSA a May 9, 2011 Notice of Violation and Compliance
Order, Docket No. UGWl 1-02 (NOV) for multiple violations ofthe Permit, including
violations of UCA § 19-5-107 and Part I.G.I ofthe Permit for exceeding Permit Ground
Water Concentration Limits (GWCL's) in Table 2 of the Permh for two consecutive
sampling events (out-of-compliance status), and Part I G.4(c) of the Permit for failing to
subsequently submit required reports and to conduct required source assessment activiUes
' Effective May 8,2012 and in accordance with Utah Code Ann § 19-1-105 the title "Executive Secretary" was
changed to "Division Director "
for wells/monitoring parameters in out-of-compliance status
4. Part E 2 of the NOV required DUSA to submit a report with revised statistics for Field
pH for several of the facility ground water monitoring wells on or before June 30,2011.
This requirement was included to address out-of-compliance status for pH at several
ground water monitoring wells, and as per a DUSA February 1,2011, letter notifying the
DIRECTOR that the out-of-compliance status appeared to be due to the Permit GWCL*s
being based on historic laboratory results instead of field measurements
C. FINDINGS OF FACT
1. DUSA receives and processes natural uranium-bearing ores, including certain specified
altemate feed materials, and possesses byproduct material in the form of uranium waste
tailings and other uranium byproduct waste generated by the Licensee's milling
operations. This facility is located approximately six (6) miles south of Blanding, Utah
on White Mesa in Sections 28,29,32 and 33, Township 37 South, Range 22 East, Salt
Lake Baseline and Meridian, San Juan County, Utah.
2. Part E.2 of the NOV required DUSA to submit a report with revised statistics for Field
pH for several of the facility ground water monitoring wells on or before June 30,2011
This requirement was included to address out-of-compliance status for pH at several
ground water monitoring wells, and as per a DUSA February 1,2011 letter notifying the
DIRECTOR that the out-of-compliance status appeared to be due to the Pennit GWCL's
being based on historic laboratory results instead of field measurements.
3. In response to the NOV, DUSA submitted several documents to provide updates and
work plans to investigate the out-of-compliance wells/monitoring parameters (and
updates regarding the revised pH statistics) in order to comply with the Act, Permit and
NOV. A summary of the pertinent updates and documents follows:
A) The pH study was not provided according to timelines set in the NOV. On June
30,2011, DUSA e-mailed the DIRECTOR requesting an extension ofthe
submittal date. This request included a summary of the suspected root cause of
pH exceedences, a discussion of actions taken and recommended future actions.
Based on DUSA's request, the DIRECTOR concurred that additional
coordination was needed in order to agree upon elements of additional pH study
related to the apparent decreasing trends
B) DUSA submitted a Plan and Time Schedule dated June 13,2011 for violations
cited in the NOV for the 1^ 2"^ 3"* and 4*^ quarters of 2010 and also included
actions for GWCL exceedences in the 1 ^ quarter of 2011.
C) DUSA submitted a Plan and Time Schedule dated September 7,2011 for out-of-
compliance parameters in the 2"^ quarter 2011.
D) DUSA submitted a Plan and Time Schedule dated January 20, 2012, for
assessment of pH under Utah Groundwater Discharge Permit UGW370004
E) DUSA submitted a Plan and Time Schedule dated April 13,2012, for
assessment of pH under Utah Groundwater Discharge Permit UGW370004
(Revised based on e-mail and telephone communication between representatives
of DUSA and the Division of Radiation Control).
4. Corrective action for the out of compliance wells/parameters will be m accordance with
the terms of this AGREEMENT, and based on outlined studies, objectives and schedules
in the DUSA Plan and Time Schedules (dated June 13,2011, September 7,2011, and
April 13,2012). If future information indicates that this agreed upon course of action is
inadequate, additional measures may be required by the DIRECTOR through separate
correspondence or formal enforcement action as deemed appropriate. DUSA retains all
administrative and judicial rights to appeal or otherwise contest such action(s).
D. AGREEMENT
1. DUSA will complete an investigation of the causes of out-of-compliance parameters and
decreasing pH trends according to *Tlan and Time Schedule" documents dated June 13,
2011, September 7,2011 and April 13,2012 (Included as Attachments A, B, and C of
this SCA respectively). DUSA shall follow all elements of the Plan and Time Schedule
Documents, as modified below, and further agrees that:
A) A sample of existing cuttings and/or core will be submitted for laboratory analysis
of pyrite for each of the monitoring wells listed on Table 5 of the April 13,2012
Plan and Time Schedule, regardless of the results of visual examination and XRF
screening Each such cutting and/or core sample will be collected from within the
vertical portion corresponding to the screened interval of the well. All other
provisions of the April 13,2012 Plan and Time Schedule remain unchanged,
except for certain modifications of deliverable timelines as detailed below.
2. DUSA will submit a source assessment report for all activities outhned in the DUSA
June 13,2011, Plan and Time Schedule to the DIRECTOR within 90 calendar days of
the effective date of this AGREEMENT. The source assessment report will detail the
results of all analysis performed and the conclusions drawn from the analyses, including
any proposed revisions to existing GWCL's. The source assessment report will also
identify any further studies that the analysis indicates should be performed, and will
propose, for DIRECTOR review and approval a plan and time schedule for completion
of any such additional studies {per the June 13, 2011, DUSA Plan and Time Schedule,
with modification as to time for submittal)
3. DUSA will submit a source assessment report for all activities outlined in the DUSA
September 7,2011 Plan and Time Schedule to the DIRECTOR within 90 calendar days
following the effective date of this AGREEMENT. The source assessment report will
detail the results of all analysis performed and the conclusions drawn from the analyses,
including any proposed revisions to existing GWCL's The source assessment report
may be combined with the source assessment report required forthe June 13,2011, Plan
and Time Schedule (Agreement 2 above) The source assessment report will also identify
any further studies that the analysis indicates should be performed, and will propose for
DIRECTOR review and approval a plan and time schedule for completion of any such
additional studies {per the September 7, 2011, DUSA Plan and Time Schedule, with
modification as to time for submittal)
4, During the pH investigation activities, DUSA will provide a written notice to the
DIRECTOR at least 14 calendar days prior to all collection of core and/or cuttings samples
for pyrite analysis. DUSA will allow the DIRECTOR the opportunity to inspect the
collection of these samples.
5. DUSA will submit a report to the DIRECTOR within 150 calendar days following the
effective date of this AGREEMENT which describes the screening, selection and
submission of samples, the results of the sample screening process and the visual and
analytical methods employed The report will provide the visual and analytical results and
will mclude an assessment of the results with regard to the potential for pyrite oxidation to
affect pH at site perched monitoring wells {per the Aprd 13, 2012, DUSA Plan and Time
Schedule, with modification as to time for sidymittal)
6 DUSA will submit a report to the DIRECTOR withm 120 calendar days of the effective
date of this AGREEMENT which provides statistical analysis of pH in all wells at the Mill
site which will quantify the decreasing trends in pH at the site as a whole and indicate which
monitoring wells have significant decreasing trends m pH. DUSA will follow the
Groundwater Data Preparation and Statistical Process Flow Chart for Calculating
Groundwater Protection Standard, White Mesa Mill Site, San Juan County, UtaK included
as figure 17 in the New Wells Background Report {per the April 13. 2012, DUSA Plan and
Time Schedule, with modification as to time for submittal)
1 If it is determined by the DIRECTOR that further analysis is required after DIRECTOR
review of the Source Assessment Reports, required by parts 2 and 3 above, DUSA will
conduct the additional assessments in a timely manner and as approved by the
DIRECTOR
E. STIPULATED PENALTIES
DUSA agrees to pay stipulated penalty amounts for not complying with this AGREEMENT.
If DUSA fails to comply with the agreements above, DUSA agrees to pay the stipulated
amounts set forth below.
1. If DUSA fails to meet any of the agreed upon timelines for submissions of reports or field
work notification mandated by tiiis AGREEMENT, DUSA agrees to pay stipulated
penalties in the amount of $500 per calendar day per violation.
2 If the DIRECTOR determines that any of the required reports listed in the
AGREEMENT above have omitted any information or content requirements or failed to
provide any of the study elements, performance standards or objectives mandated by the
AGREEMENT, (e g. failure to provide full statistical analysis for revised GWCL's where
applicable), the DIRECTOR will advise DUSA by written notice and DUSA will be
required to remedy such omissions or failures on or before a due date as determined
appropriate by the DIRECTOR. If DUSA fails to remedy such omissions or failures on or
before the due date, DUSA agrees to pay stipulated penalties in the amount of $500 per
calendar day for every day a required report remains incomplete
3. DUSA agrees to pay any required penalties within 30 calendar days of wntten notice
from the DIRECTOR, in the form of a check, made payable to the State of Utah, and
delivered or mailed to.
Division of Radiation Control
Utah Department of Environmental Quality
PO. Box 144850
195 North 1950 West
Salt Lake City Utah, 84114-4850
F. NOTICE
Compliance with the provisions of this ORDER is mandatory. Providing false information may
subject DUSA to further civil penalties or criminal fines.
UCA § 19-5-115 provides that a violation of the ACT or a related order may be subject to a civil
penalty of up to $10,000 per day of violation. Under certain circumstances of willfulness or
gross negligence, violators may be fined up to $25,000 per day of violation.
AGREED to tiiis J2^ay of --^^Vj^^'^ , 2012.
DENISO S (USA) CORR UTAH DIVISION OF RADIATION CONTROL
By
•rydenlund
Vice President and Counsel
Denison Mines (USA) Corp.
Rusty L(inc\berg
Director
F \0USA\OOC Plan and Time Schedule and pH\SCA\Revlsed SCA UGW12-03\OUSA White Mesa OOC and pH SCA Final docx
Attachment A:
DUSA Transmittal of Plan and Time Schedule under Utah Ground Water Discharge Permit UGW37G004
Part IG 4{d), June 13,2011
WHITE MESA MILL
State of Utah Ground Water Discharge Permit UGW370004
Plan and Time Schedule
Under Part I.G.4 (d)
For
Violations of Part I.G.2 for Constituents in the First, Second, Third and Fourtii Quarters of
2010 and First Quarter of 2011.
Denison Mines (USA) Corp.
1050 17*'' St., Suite 950
Denver, CO 80265
June 13,2011
1. INTRODUCTION
Denison Mines (USA) Corp. ("Demson'*) operates the White Mesa Uranium Mill (the *'Miir'),
located near Blanding Utah, under State of Utah Ground Water Discharge Permit UGW370004
(tiie ^'Permit").
This is tiie plan and time schedule (tiie "Plan") required under Part I.G,4(c) of tiie Permit relating
to violations of Part 1.G.2 of tiie Permit for tiie I"*, 2"*^, 3"* and 4^ quarters of 2010 and tiie first
quarter of 2011. Part I.G.2 ofthe Permit provides that out-of-compliance status exists when tiie
concentration of a pollutant in two consecutive samples from a compHance monitoring point
exceeds a ground water compliance limit ("GWCL") in Table 2 of the Permit.
The Permit was onginally issued in March, 2005, at which time GWCLs were set on an intenm
basis, based on fractions of State Ground Water Quality Standards or the equivalent, without
reference to natural background at tiie Mill site. The Permit also required tiiat Denison prepare a
background groundwater quahty report to evaluate all historic data for the purposes of
estabhshmg background groundwater quality at the site and developing GWCLs under tiie
Permit
As required by then Part I.H.3 of tiie Permit, DUSA submitted the following to the Co-Executive
Secretary (tiie "ExecuUve Secretary") of tiie State of Utah Water Quality Board:
• A Revised Background Groundwater Quality Report' Existing Wells For Denison Mines
(USA) Corp. 's MiU 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
Backgroimd Data. Background Groundwater Quality Report' Existing Wells For
Denison Mines (USA) Corp. 's Mill Site, San Juan Coimty, Utah, November 16, 2007,
prepared by INTERA, Inc. (tiie "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. Apnl 30, 2008, prepared
by INTERA, Inc. (the "New Wells Background Report, and togetiier with tiie Existing
WeUs Background Report and tiie Regional Background Report, tiie "Background
Reports").
Based on a review ofthe Background Reports and other information and analyses the Executive
Secretary re-opened the Pemiit and modified tiie GWCLs to be equal to tiie mean concentraUon
of background for each constituent on an intrawell basis plus two standard deviations or the
equivalent. The modified GWCLs became effective on January 20,2010.
The Executive Secretary issued a Notice of Violation and Compliance Order, Docket No.
UGWl 1-02 (tiie "Notice"), dated May 9, 2011, based on tiie State of Utah Department of
Environmental Quality ("UDEQ"), Division of RadiaUon Control ("DRC") findings from the
review of tiie Mill's 1"^, 2"^ and 3"* quarter 2010 Groundwater Monitonng Reports. The Notice
cited five violations of the Permit, including a violation under Utah Water (^ality Act (UC 19-5-
107) and Parts I.C.I of tiie Permit for failing to protect tiie waters of tiie state m tiiat six
contaminants have exceeded their respective GWCLs in Table 2 of the Permit for two
consecutive sampling events.
Section E.4 of the Notice orders Demson to prepare and submit within 30 calendar days of
receipt of the Notice, a wntten plan and time schedule, for Executive Secretary approval, to fully
comply with the requirements of Part I.G,4(c) of the Permit, mcluding, but not limited to.
(i) submittal of a wntten assessment of the source(s) of the six contaminants and multiple
wells listed m Table 3 of the Notice, including: Cadmium, Manganese, Sdenium,
Thallium, Uranium , and Total Dissolved Solids ("TDS*');
(ii) submittal of a written evaluation of the extent and potential dispersion of said
groundwater contamination; and
(iii) submittal of a wntten evaluation of any and all potential reraedial actions to restore and
maintain groimd 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 comphance wells
will be returned to and maintained m compliance with their respective GWCLs.
On February 14, 2011 Denison submitted a notice (tiie "4* Quarter 2010 Exceedance Notice") to
the Executive Secretary under Part I.G. 1(a) of the Permit providing notice that tiie
concentrations of specific constituents m the monitoring wells at tiie Mill exceeded their
respective GWCLs for the 4* quarter of 2010 and indicating which of those constituents had two
consecutive exceedances during that quarter
On May 13,2011 Demson submitted a notice (the "1st Quarter 2011 Exceedance Notice") to the
Executive Secretary under Part IG.l(a) ofthe Permit providing notice that tiie concentrations of
specific constituents in the monitormg wells at the Mill exceeded their respective GWCLs for the
1^ quarter of 2011 and indicating which of those constituents had two consecutive exceedances
during that quarter. Some constituents had two consecutive exceedances dunng the I'' quarter of
2011 that had not aheady been properly identified as having had two consecutive exceedances m
tiie 1'^, 2""^ or 3"^^ quarters of 2010, as identified in tiie Notice, or m the 4**' quarter of 2010, as
identified m the 4"* Quarter 2010 Exceedance Notice.
Although not subject to the Notice, tiiis Plan also covers the constituents m violation of Part
I.G.2 of the Permit that were identified as being in violation in the 4"* Quarter 2010 Exceedance
Notice and/or the 1 ""^ Quarter 2011 Exceedance Notice.
2, CONSTITUENTS AND WELLS SUBJECT TO THIS PLAN
The following constituents and wells have been identified in the Notice, tiie 4* Quarter 2010
Exceedance Notice and/or the 1^' Quarter 2011 Exceedance Notice as being in out-of-compliance
status under Part IG 2 of the Permit':
Table 1
Constituents and Wells Subject to this Flan
Constituent Monitoring Event POC WeU GWCL Result
Cadmium
2°''Qtr, 2010 (5/6/2010)
3"^ Qtr 2010 (9/21/2010)
4* Qtr2010 (11/17/2010)
I'* Qtr 2011 (2/10/2011)
MW-24 2 5 ng/L 4.28 ng/L
5.06 ng/L
3.22 ng/L
2.78 ng/L
Manganese
l^'Qtr 2010(2/10/2010)
2"*^ Qtr 2010(4/28/2010)
October 2010 (10/20/2010)
4*^ Qtr 2010 (11/11/2010)
December 2010 (12/15/2010)
MW-11 131 ng/L 134 ng/L
137 ng/L
141 ng/L
133 ng/L
158 ng/L
Selenium
2"** Qtr 2010(4/27/2010)
3"* Qtr 2010 (9/20/2010)
4*'* Qtr 2010(11/19/2010)
Qtr 2011 (2/15/2011)
MW-12 25 ng/L 25.7 ng/L
31.9 ng/L
27.6 ng/L
39 pg/L
Selenium
2™" Qtr 2010 (4/27/2010)
August 2010 (8/24/2010)
January 2011 (1/10/2011)
1'^ Qtr 2011 (2/1/2011)
MW-30 34 ng/L 35.3 ng/L**
35 6 ng/L**
36.2 ng/L
34.7 ne/L
Selenium
4"^ Qtr 2010 (11/19/2010)
1" Qtr 2011 (2/15/2011)
MW-3 37 ng/L 38,8 ng/L
40.5 ng/L
Selenium
4"^ Qtr 2010 (11/22/2010)
Qtr 2011 (2/16/2011)
MW-3A 89 ng/L 94.8 ng^L
99 ng/L
Thallium
January 2010 (1/27/2010)*
March 2010 (3/22/2010)*
2°'* Qtr 2010 (5/4/2010)
3"* Qtr 2010 (9/15/2010)
4*^ Qtr 2010(11/18/2010)
l"" Qtr 2011 (2/15/2011)
MW-18 1.95 \isfL 3 32 ng/L*
3 91 ng/L*
3.73 ng/L
3.64 ng/L
3.57 ng/L
3.49 ng/L Thallium
2"** Qtr 2010 (5/6/2010)
3"* Qtr 2010 (9/21/2010)
4'^Qtr 2010(11/17/2010)
l"" Qtr 2011 (2/10/2011)
MW-24 1.0 ng/L 1.3 ng/L
1.57 ng/L
1.09 ng/L
1.42 ng/L
Uranium I'^Qtr 2010(2/2/2010) MW-26 41.8 ng/L 58.7 ng/L
' Table I includes the resuhs indicated on the Notice for the constituents m question plus any additional consecutive
exceedances generated firom the 4* quarter 2010 and/or the 1" quarter 2011 results It does not mclude every
exceedance of the GWCLs for those penods
2"" Qtr 2010(4/22/2010) 66.7 ng/L
4'" Qtr 2010 (11/11/2010)
1"^ Qtr 2011 (2/14/2011)
MW-5 7.5 ng/L 11.6 ng/L
29.5 ng/L
TDS
r Qtr 2010(3/15/2010)*
2"''Qtr 2010 (5/3/2010)
4"^ Qtr 2010 (11/12/2010)
Qtr 2011 (2/9/2011)
MW-27 1,075 mg/L 1,080 mg/L*
1,160 mg/L
1,110 mg/L
1.090 mg/L
Sulfate
4'" Qtr 2010 (11/9/2010)
l**" Qtr 2011 (2/1/2011)
MW-31 532 mg/L 539 mg/L
538 mg/L Sulfate 4"* Qtr 2010 (11/22/2010)
l"" Qtr 2011 (2/16/2011)
MW-3A 3,640 mg/L 3,850 mg/L
3,730 mg/L
Fluoride 4'" (^2010 (11/19/2010)
l"" Qtr 2011 (2/15/2011)
MW-3 0.68 mg/L 0.77 mg/L
0.69 mg/L
• Samples that were not required to be taken under the Perrait and hence were incorrectly relied upon in the
Notice to determine compliance status under Part 10 2 of the Permit However, for all of those constituents
and wells, consecuUve exceedances m subsequent quarters have resulted m the need to include those
constituents and wells in this Plan
The Notice incorrectly stales these as two consecuUve exceedances However, there was an intervemng
sample result taken in July 2010 of 33 5 ^g/L that was less than the GWCL Therefore, the indicated sample
results were incorreotly relied upon m the Notice to deterrame compHance status under Part IG 2 of the
Permit However, consecutive exceedances in subsequent quarters have resulted in the need to mclude
selemum tn MW-SO m this Plan.
It should be noted tiiat tiie Notice, the 4^ Quarter 2010 Exceedance Notice and l^ Quarter 2011
Exceedance Notice identify a number of wells with consecutive exceedances of Nitrate + Nitnte
and/or Chloride (MW-26, MW-27, MW-28, MW-30 and MW-31), Chlorofonn and
Dichloromethane (MW-26), and pH (less than the respective GWCLs for pH m a number of
wells) However, none of those constituents are included in this Plan, for the reasons stated m
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 + Nitnte and Chlonde are associated witii tiie Nitrate/Chloride plume, and are
currentiy being investigated by Denison pursuant to a January 28, 2009 Stipulated Consent
Agreement. Witii respect to pH, Denison notified DRC in a letter dated February 1, 2011 that
explained the existing GWCLs for groimdwater pH are in error due to reliance on histoncal
laboratory values instead of field measurements, and proposed a plan to submit revised
descnptive statistics for Field pH to be used as revised GWCLs.
The followmg observations can be made from Table 1:
• Consecutive exceedances have been observed for Manganese in MW-ll, Thallium m
MW-18, Selemum m MW-30 and TDS m MW-27 m tiie 4^^ Quarter 2010 and/or tiie 1"^
Quarter 2011 This justifies inclusion of these constituents on Table 1, but at later dates
than indicated by DRC m the Notice, based on later data than the data used by DRC, as
discussed m Denison's Jime 13, 2011 response to the Notice; and
• The followmg new constituents and wells have demonstrated consecutive exceedances,
based on the 4* Quarter 2010 and/or the (Quarter 2011 results: Selemum m MW-3 and
MW-3 A, Uranium in MW-5, Sulfate m MW-3 and MW-31 and Fluonde m MW-3
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 in Wells With Previously Identified Rising Trends
The followmg constituents were identified m the Background Reports as having statisUcally
significant rising trends, due to natural background influences:
Table 2
Constituents with Previously Identified Rising Trends
Constituent WeU Reference
Manganese MW-ll Table 16, Existing Wells
Background Report
Selenium
MW-12 Table 16, Existing Wells
Background Report Selenium MW-3 Table 16, Existing Wells
Background Report
Thallium MW-18 Table 16, Existing Wells
Background Report
Uranium MW-26 Table 16, Existing Wells
Backgroimd Report
It is worth noting that, although a rising trend m sulfate has not been previously identified in
MW-3A, a rising trend in Sulfate has previously been identified m MW-3, which is nght beside
MW-3A
3.2 Constituents m Pumping Wells
Of the constituents listed in Table 1 above, Uramum in MW-26 is tiie only constituent m a
pumping well
3 3. Constituents Potentiallv 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 fa-ends in pH
in MW-25, MW-27, MW-28, MW-3A, MW>3, MW-12, MW-14 and MW-17. INTERA also
noted that, while not statistically significant, on a review of the pH time plots m all existing
wells, there appeared to be a general decreasing trend in pH in all wells.
The mobility in groundwater of the following constituents is sensitive to decreases m pH:
Table 3
Constituents PotentiaUy Impacted by Decreasing Trends in pH
Constituent WeU
Cadmium MW-24
Manganese MW-ll
Selenium
MW-12
Selenium MW-30 Selenium MW-3 Selenium
MW-3A
Thallium MW-18 Thallium MW-24
Uranium MW-5 Uranium MW-26
3.4. Other Constituents and Wells
The followmg constituents m Table I do not fall withm one of the previous tiiree categones:
Table 4
Other Constituents
Constituent WcU
TDS MW-27
Sulfate MW-3A Sulfate MW-31
Fluonde MW-3
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 ensure that Permit limits will not be exceeded at the compliance
monitonng point and that, to the extent applicable, discharge mimmization technology and best
available technology will bQ reestablished
Given the recent analyses in the Background Reports and other recent information relating to the
Chloroform and Nitrate/Chloride investigations at the site, Denison believes that all of tiie
exceedances are likely due to background influences (includmg a natural decreasing trend in pH
across the site, rising water levels in some wells and other factors), disruption of tiie aquifer by
pumpmg and/or tiiie geochemical influences of the existing chloroform and nitrate/chloride
plumes
Therefore, tiie first step in tiie analysis will be to perfonn an assessment of tiie potential sources
for each exceedance to determine whether the exceedance is due to background influences or
Mill activities. If an exceedance is determined to be due to background influences tiien it will
not be necessary to perform any further evaluations on the extent and potential dispersion of tiie
contamination or to perform an evaluation of potential remedial actions. Monitonng will
continue, and where appropnate revised GWCLs will be proposed to reflect changes in
background conditions at the site.
However, if any of tiie exceedances 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 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 compliance
monitoring point.
This two-step approach is necessary, because, in light ofthe vaned background conditions at tiic
site and previously identified background ti-ends, it can't be assumed tiiat consecutive
exceedances of a constituent in a well represents contammation that has been introduced to the
groundwater. It is first necessary to establish whether or not the exceedances represent
background influences.
4.2. Assessment for each Category
The approach and scope of review for each of tiie different categories described above, is
descnbed in more detail below.
4 21. Constituents With Pre-Existing Rising Trends
It was well known at ttie time of setting tiic current GWCLs that certain constitiients had nsing
trends. On page 3 of tiie Existing WeU Background Report, INTERA concluded:
*There arc numerous cases of both increasing and decreasing trends in
constitiients in upgradient, far downgradient, and Mill site wells, which provide
evidence that tiiere are natural forces at work that are impacting groundwater
quality across the entire site
In almost all cases where there are increasing trends in constituents in wells at the
site, there are increasing trends in tiiose constituents in upgradent wells.
Furthermore, and more importantly, in no case is there any evidence in tiie wells
m question of increasing trends in chlonde, which is considered tiie raost mobile
and best indicator of potential tailings cell leakage at the site. We consider the
combination of these factors to be conclusive evidence tiiat all increasmg trends at
the site are caused by natural forces and not by Mill activities".
The Groundwater Data Preparation and Statistical Process Flow for Calculating Groundwater
Protection Standards, White Mesa Mill Site, San Juan County, Utah, which was approved by tiie
Executive Secretary, included as Figure 19 to tiie Existing Wells Background Report, states in
tiie final decision box, for circumstances where the data indicated an mcreasmg tirend (decreasing
m tiie case of pH), the following:
"Consider modified Approach to GWCL
(Use Post Second Quarter 2005 Data only?)
(Re-evaluate on Renewal?)"
The nsing trends m each ofthe constituents listed in Table 2 above were analyzed by INTERA
in Section 11 of the Existing Wells Background Report Additional analysis relating to rising
uranium ti-ends in vanous wells at the site, which includes a discussion on possible causes of tiie
ti-ends, is found in Section 12 of the Existing Wells Background Report.
Further, a study entitied 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 was prepared by T. Grant Hurst and D, Kip Solomon,
Department of Geology and Geophysics, University of Utah, May 2008 (the "University of Utah
Study").
On pages (ii) and (iii) of tiie Executive Summary to the University of Utah Study, Hurst and
Solomon note that:
"Increasmg and elevated trace metal concentrations m monitonng wells at a
uranium processmg facility near Blandmg, UT, may indicate leakage from tailings
cells is occumng. To investigate this potential problem, a groundwater study was
done to charactenze groundwater flow, chemical composition, noble gas
composition, and age.
"The data show that groundwater at the Mill is largely older than 50 years, based
on apparent recharge dates frora chlorofluorocarbons and tntium concentrations.
Wells exhibiting groundwater that has recharged witiiin the last 50 years appears
to be a result of recharge from wildlife ponds near the site. Stable isotope
fingerprints do not suggest contamination of groundwater by taihngs cell leakage,
evidence that is corroborated by trace metal concentrations similar to historically-
observed concentrations."
Included in the University of Utah Study sampling and analysis were the following wells listed
in Table 1 above: MW-3, MW-3A, MW-5, MW-11, MW-18, MW-27, MW-30 and MW-31
It has been established, then, that continued rising trends m the wells listed in Table 2 above are
not inconsistent with natural background, and m fact were accepted as natural background for
purposes of setting the revised GWCLs m January 2010. The pnmary focus of the source
assessment for the wells listed m Table 2 above will therefore be to deterrame whether or not
there is any new mformation that would suggest tiiat the previous analysis conducted in the
Existing Wells Background Report has changed since the date of tiiat Report. This analysis v^ll
include tiie following for each constituent hsted in Table 2:
(i) A geochemical analysis that will evaluate the behavior of all of the constituents in the
well in question to detennine if there are any changes m the behavior of indicator
constituents, such as Chlonde, Sulfate, Fluonde and Uranium since the date of the
Existing Wells Background Report that may suggest a change m the behavior of that
well since the date of that Report;
(il) A mass balance analysis that will evaluate the observed concentrations of tiie
constituent in light of the concentrations in Mill tailings and the presence or absence of
any mounding at tiie location of tiie well in question; and
(iii) In cases where the wells in question are distant from the Mill's tailings cells, a
hydrogeologic analysis will be performed to determine the plausibility of impact from
Mill tailings
The foregoing analysis will be included m a report (the "Source Assessment Report") to be
prepared by an independent engineenng consultant.
If no significant changes are identified that would suggest that the previous analysis conducted in
the Background Reports for the constituents in question has changed, then Denison will propose
changes to the GWCLs for those wells to better reflect background concentrations at the site.
If sigmficant changes are identified that caimot be attiibuted to background influences, 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, as well as
potential remedial actions.
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
Dunng 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 outiiers. Statistical outiiers may need to be removed, especially if
an error or discrepancy can be identified, so that subsequent compliance tests can be
10
unproved If trends are indicated, a change in the statistical method or approach may
be warranted "
and
"Site-wide changes in the underlymg aquifer should be identifiable as sunilar 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 Gmdance, EPA further states:
"5.3.4 UPDATING WHEN TRENDS ARE APPARENT
An increasing or decreasing trend may be apparent between tiie existing
background and the newer set of candidate background values, either using a time
series plot or applymg Chapter 17 trend analyses. Should such tirend data be
added to the existing background sample? Most detection monitonng 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-^ or Wilcoxon rank-sum test between the existing and
candidate background data sets is non-significant More severe or continumg
trends are hkely to be flagged as SSIs by formal intrawell prediction Hmit or
control chart tests.
With interwell tests, a stix)nger trend in the common upgradient background may
signify a change m natural groundwater quality across the aquifer or an
incomplete characterization of the full range of background vanation. 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 "
4,2.2, Constituents in Pumping Wells
MW-26 IS a pumping well In Section 7.3.1 of tiie Existing Wells Background Report, INTERA
concluded that:
" . . chloroform pumping wells are being mampulated and the impact on the
quality of the water m those wells from tiie pumping is uncertain and cannot be
predicted with enough certainty to establish compliance standards under the
GWDP. For example, pumping wells are intended to pull water m from areas of
11
the perched aquifer that would normally flow into otiier wells. In fact, tiie
pumping wells are having the effect of drawing down water levels m other wells
(see for example Figure 2 of Appendix D of the second quarter 2007 Chloroform
Monitonng report) This water may be associated with its own background
quality that will impact the water quality in the pumping well. Any increasing or
decreasing trends m constituent in chlorofonn pumping wells, such as MW-26,
are therefore not unexpected and should be given littie, if any, weight in analyzuig
potential impacts to groundwater from Mill activities. These impacts should be
subject to the chloroform NOV and not result in parallel out-of-compliance
situations under the GWDP.
For this reason, we believe that MW-26 should continue to be monitored under
tiie GWDP, but that DUSA should not be subject to any out of compliance
situation under the GWDP relating to MW-26."
This concem was acknowledged by the Executive Secretary in the September 2009 Statement of
Basis issued m connection with approval of the revised GWCLs. On page 23 of tiiat document,
the Executive Secretary stated that:
"It should be noted that, because MW-26 is a pumping well for chloroform
removal, concentrations of all constituents m that well are subject to potential
vanation over time as a result of the pumping activity. This will be taken into
account by the Executive Secretary in determinmg compliance for this well."
MW-26 IS included on Table 1 above because of consecutive exceedances of tiie GWCL for
uramum m the l*^ and 2"*^ quarters of 2010. Subsequent data show that the concentrations of
uramum in MW-26 m the samplmg events in 2010 and through the first quarter of 2011 range
from 29.6 ng/L to 72.7 ng/L, witii eight of the tiiirteen sample results being less tiian tiie GWCL
of 41.8 ng/L, The most recent result was 31.8 ng/L for the March 2011 monthly sampling event.
This erratic behavior is not unexpected for a pumphig weU such as MW-26, and is not
inconsistent with natural background. The primary focus of the source assessment for uramum
in MW-26 will therefore be to determine whetiier or not tiiere is any new information that would
suggest that the previous analysis conducted in the Existing Wells Background Report, has
changed since the date of that Report. This analysis will include the following.
(i) A geochemical analysis that will evaluate the behavior of all of the constituents m MW-
26 to detennine if there are any changes in the behavior of indicator constituents, such
as Chlonde, Sulfate, Fluonde and Uramum since tiie date of the Existing Wells
Background Report that may suggest a change m tiie behavior of that well since the date
of tiiat Report. However, it is not expected that tins analysis will yield any conclusive
findings, given the dynamic nature of the well; and
(li) A mass balance analysis that will evaluate the observed concentrations m light of the
concentrations m Mill tailings.
12
The foregoing analysis will be included in the Source Assessment Report.
If no significant changes are identified that would suggest that the previous analysis conducted in
the Background Reports for the constituents in question has changed, tiien Denison will continue
to pump and monitor tiiat well. Since GWCLs for pumping wells have no meaning, for the
reasons discussed above, Denison does not intend to propose revised GWCLs for MW-26.
If significant changes are identified in the Source Assessment Report, that cannot be attnbuted to
the pumping itself or to background influences, then Demson 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. Denison will also evaluate potential remedial actions
that may be appropriate. However, continued pumping is probably the best remedial action at
this time.
4 2.3. Constituents Potentially Impacted by Decreasing Trends in pH across the Site
As mentioned above, Denison has observed a decreasing trend m pH in a number of monitonng
wells across the Mill site. The mobility in groundwater of a nuraber of constituents listed in
Table I is sensitive to decreases in pH. Those constituents are listed in Table 3 above.
It should be noted that a number of the wells hsted m Table 3 are also wells tiiat were included in
the University of Utah Stiidy. Those are wells MW-3, MW-3A, MW-5, MW-11, MW-18 and
MW-30. This gives further support to tiie possibility that increases in concentirations of tiiese
constituents in those wells are due to natural influences, such as natural changes m pH, rather
than to Mill activities
The pnmary focus of the source assessment for the wells listed in Table 3 above will be two-
fold. First, Denison will deterrame whetiier or not there is any new information that would
suggest that the previous analysis conducted m the Existing Wells Background Report has
changed since the date of that Report. This analysis will include the following for each
constituent hsted in Table 3:
(i) A geochemical analysis that will evaluate the behavior of all of the constituents in the
well in question to determine if there are any changes m the behavior of indicator
constituents, such as Chloride, Sulfate, Fluoride and Uranium since the date of the
Existing Wells Background Report that may suggest a change in the behavior of tiiat
well since the date of that Report;
(n) A mass balance analysis that will evaluate tiie observed concentiations m li^t of the
concentrations in Mill tailings and the presence or absence of any mounding at the
location of the well in question; and
(hi) In cases where the well in question is distant from the Mill's tailmgs cells, a
hydrogeologic analysis will be performed to deterraine the plausibility of impact from
Mill tailings.
13
Second, a pH analysis will be performed for each constituent that will:
(iv) Review the behavior of pH m the well in question to deterrame if there has been a
sigmficant decrease in pH in the well, and
(v) Analyze the expected irapact from any such decrease m pH on tiie concenti-ation ofthe
constituent m question m the well, based on currentiy available information.
The foregoing analyses (botii steps) will be included in the Source Assessment Report.
If no significant changes are identified that would suggest that the previous analysis conducted in
the Background Reports for the constituents m question has changed, other than what would be
expected from decreasing trends m pH, then Denison will propose changes to the GWCLs for
those weUs to better reflect background concentrations at the site.
If significant changes are identified that cannot be attnbuted to changes in pH or other natural
phenomena, then Denison will propose to the Executive Secretary further analysis tiiat may be
requured in order to identify the source and the extent and potential dispersion of the
contamination, as well as potential remedial actions.
4 2.4. Other Constituents and Wells
Table 4 sets out other constituents that do not fall within the categones considered in Sections
4 2 1, 4.2 2 and 4,2.3 above. However, all of those constituents are in wells tiiat were included in
tiie University of Utah Study.
The primary focus of the source assessment for the wells listed m Table 4 above will again be to
determine whether or not there is any new information that would suggest that tiie previous
analysis conducted m the Existing Wells Background Report has changed since the date of tiiat
Report. This analysis will include the following for each constituent hsted in Table 4:
(i) A geochemical analysis that will evaluate the behavior of all of the constituents in the
well m question to determine if there are any changes m the behavior of indicator
constituents, such as Chloride, Sulfate, Fluonde and Uranium since the date of the
Existing Wells Background Report that may suggest a change m tiie behavior of tiiat
well since the date of that Report;
(ii) A mass balance analysis that will evaluate the observed concentrations in Ught of the
concentrations m Mill tailings and the presence or absence of any moundmg at the
location of the weU in question;
(in) In cases where the well in question is distant frora the Mill's tailings cells, a
hydrogeologic analysis wiU be perfonned to determine the plausibility of impact from
Mill tailmgs,
14
(iv) An analysis of tiie extent, if any, to which the constituents listed in Table 4 may be
influenced by geochemical chfuiges caused by migrating nitirate and/or chloride or
chloroform from the existmg plumes; and
(v) An analysis of tiie extent, if any, to which the constituents listed in Table 4 may be
influenced by changes in other constitiients in ground water tiiat have resulted from
changes in pH or any other natural phenomenon.
The foregoing analysis will bemcluded in the Source Assessment Report.
If no significant changes are identified tiiat would suggest tiiat the previous analysis conducted in
tiie Background Reports for the constituents in question has changed, then Denison will propose
changes to the GWCLs for those wells to better reflect background concentiations at the site
If significant changes are identified that are attiibutable to geochemical changes caused by either
tiie mtrate/chloride plume or tiie chloroform plume, tiien the constitiients in Table 4 should be
considered in connection with the apphcable plume.
If significant changes are identified that cannot be attiibuted to one of tiie existing plumes, or
otiier background influences, then Denison will propose to the Executive Secretary further
analysis that may be required in order to identify the source and tiie extent and potential
dispersion of the contamination, as well as potential remedial actions
4.3, Experts Reports to be Prepared
The Source Assessment Report wiH detail the results of all of the analysis to be performed and
the conclusions to be dravm from such analyses, including any proposed revisions to existmg
GWCLs The Source Assessment Report wiU also identify any further studies that the analysis
indicates should be performed, and wiU propose, for Executive Secretary review and approval, a
plan and schedule for completion ofany such additional studies.
If further analysis is required after completion of the Source Assessment Report, Denison and the
Executive Secretary wiU agree on the scope of tiiat analysis, based on the findmgs 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 tiie Executive Secretary witiiin 60 days after
approval of this Plan
Any further studies tiiat are identified in the Source Assessraent Report or otiierwise identified
by the Executive Secretary as being reqmred in order to fulfill tiie reqmrements of Part I.G.4(c)
of tiie Permit or tiie Notice, will be prepared and submitted by Denison m accordance witii a
schedule to be approved by the Executive Secretary,
15
6. CONCLUSION
Background at the Mill site was recentiy 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 MiU operations. Both of those
studies also acknowledged that there are natural influences at play that have given nse to
increasmg water trends and general vanabihty of background groundwater at the site.
Given tiie vaned 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 m a monitonng well means that contamination has been introduced to groimdwater m
that well. The exceedances may very well be the result of background influences. The approach
m this Plan therefore is to first determine if the recent exceedances 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
In detcmimmg whether or not an exceedance is tiie result of background influences, it is not
practicable to redo the Background Reports and University of Utah Study each time a monitoring
well shows consecutive exceedances, particularly where the exceedance is consistent with those
recent analyses The focus should tiierefore be on identifying any changes in the circumstances
identified m tiiose studies.
Based on the infonnation available at this time, Denison believes that the exceedances observed
are the result of natural influences and reflect tiie need to adjust some ofthe GWCLs for the site.
15
SIGNATURE AND CERTIFICATION
This document was prepared by Denison Mines (USA) Corp. on June 13,2011.
DENISON MINES (USA) CORP.
By:
Dayud p. Frydenlund
Vice President, Regulatory Affairs and Counsel
Certification*
1 certify, under penalty of law, tiiat tiiis document and all attachments were
prepared under my direction or supervision in accordance with a system designed to
assure that qualified personnel properly gather and evaluate the infonnation submitted.
Based on my inquiry of the person or persons who manage the system, or those persons
directly responsible for gathering the mformation, the information submitted is, to the
best of my knowledge and belief, true, accurate, and complete. I am aware that there are
Significant penalties for subnutting false infonnation, including the possibiHty of fine and
imprisonrfiint folyfaiowing violations.
OavjM?. Frydenlund
Vicerresidcnt, Regulatory Affairs and Counsel
Demson Mines (USA) Corp.
Attachment B
DUSA Transmittal of Plan and Time Schedule under Utah Ground Water Discharge Permit UGW370004
Part IG 4(d), September 1,2011
WHITE MESA MILL
State of Utah Ground Water Discharge Pennit UGW370004
Plan and Time Schedule
Under Part I.G.4 (d)
For
Violations of Part LG,2 for Constituents in the Second Quarter of 2011
Denison Mines (USA) Corp.
1050 17*^ St., Suite 950
Denver, CO 80265
September 7,2011
1. INTRODUCTION
Denison Mines (USA) Corp. ("Demson") operates tiie White Mesa Uranium Mill (the "MiU"),
located near Blanding Utah, under State of Utah Ground Water Discharge Pennit UGW370004
(tiie "Permit").
This is the plan and time schedule (tiie "Plan") required under Part I.G.4(c) of the Permit relating
to violations of Part I.G.2 of the Pennit for the 2""^ quarter of 2011 Part I.G 2 of the Permit
provides that out-of-comphance status exists when the concentration of a poUutant in two
consecutive samples from a compliance monitoring point exceeds a groundwater compliance
limit ("GWCL") in Table 2 ofthe Pemut
The Permit was onginally issued in March, 2005, at which time GWCLs were set on an intenm
basis, based on fractions of State Ground Water Quality Standards or the equivalent, without
refercncc to natural background at the MiU 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 tiie
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 Backgroimd Groundwater Quality Report' Existing Wells For Denison Mines
(USA) Corp.'s MiU Site, San Juan County. Utah, October 2007, prepared by INTERA,
Inc. (the '^Existing Wells Background Report");
• A Revised Addendum' - Evaluation of Available P re-Ope rational and Regional
Background Data. Background Groundwater Quality Report' Existing Wells For
Denison Mines (USA) Corp.'s MiU 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 MUl Site. San Juan County, Utah, Apnl 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 concenti-ation
plus two standard deviations or the equivalent. The modified GWCLs became effective on
January 20, 2010
Sectton IG 4(c) of the permit requires tiiat DUSA submit a wntten plan and time schedule, for
Executive Secretary approval, includmg, but not limited to.
(i) submittal of a written assessment of the source(s);
(ll) submittal of a wntten evaluation of the extent and potential dispersion of said
groundwater contamination; and
(tii) 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 m question, lo ensure that* 1) shallow groundwater quality at the facility
will be restored and 2) the contaminant concentrations in said pomt 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 monitonng 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 l.G,2 of the Pernut that were identified as
being in violation m the 2"^^ Quarter 2011 Exceedance Notice for the first time beginning m 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-
compUance status under Part I G.2 of the Permit m the 2"*^ Quarter 2011 Exceedance Notice.
Table 1
Constituents and WeUs 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 r Qtr 2011 (2/15/2011)
2"*^ Qtt 2011 (4/12/2011)*
2"*'Qtr20ll (6/7/2011)
MW-35 7.5 ng/L 12.7 ng/L
19 9 ng/L
21.7 ng/L
Manganese
Qtt- 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 descnbed in the Q2 2011
Groundwater Report submitted under separate cover on August 31,2011 Both results arc included
It should be noted that the Notice of Vioiauon and Compliance Order, Docket No. UGWl 1-02
(the "Notice"), dated May 9, 2011 and the 2"*^ Quarter 2011 Exceedance Notice identify a
number of wells with consecutive exceedances of Nitrate + Nitrite and/or Chloride (MW-26,
MW-27, MW-28, MW-30 and MW-31), Chloroform and Dichloromethane (MW-26), and pH
(less than tiie respective GWCLs for pH in a number of wells). However, none of those
constituents are included m this Plan, for tiie 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 + Niti-ite and Chlonde are
associated with the Nitrate/Chloride plume, and are currentiy being investigated by Denison
pursuant to a January 28, 2009 Stipulated Consent Agreement Denison notified DRC in a letter
dated February 1, 2011 tiiat 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 m the 2"** quarter
2011 that also had consecutive exceedances m 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 ConsecuUve exceedances which occuned in previous reporting penods are
discussed in the previous Plan and Time Schedule Under Part LG.4 (d), submitted on June 13,
2011
3. CATEGORIES FOR ANALYSIS
The constituents and wells listed in Table I can be separated into a number of different
categones, as follows:
3 I. Constituents Potentiallv Impacted bv Decreasing pHTrends Across the Site
Denison has observed a decreasing trend in pH in a number of monitoring wells across the Mill
site. See the discussion m 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 m pH
in MW-25. INTERA also noted tiiat, while not statistically significant, on a review of the pH
time plots m all existing wells, there appeared to be a general decreasing trend m pH m all wells.
The mobihty 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
Uramum MW-25
3 2 Newlv 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 mtenm GWCLs in MW-35. However, since
background has nol been established in MW-35, the exceedances of these intenm 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 categones:
Table 3
Other Constituents
Constituent WeU
TDS MW-18
TDS m 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 m 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 al the Denison Mines,
USA. White Mesa Uranium MiU 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 quahty 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 mtenm 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 monitonng for TDS continue at MW-18 while Demson
prepares, and the Executive Secretary evaluates, an application for a revised GWCL for TDS in
that weU
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 wiU 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 wUl proceed to the next step and will consider the extent and potential dispersion
of the contamination, and/or wiU perform an evaluation of potential remedial actions to restore
and maintain groundwater quality to insure that Permit limits will not be exceeded at tiie
applicable point of compliance.
This two-step approach is necessary, because, in light of the varied background conditions at tiie
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 descnbed above, is
described in more detail below,
4 2.1 Constituents PotentiaUy Impacted hy Decreasing Trends in pH across the Site.
As mentioned above, Denison has observed a decreasing trend m pH in a number of monitoring
wells across tiie 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, wiU
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 tiie GWCL for uranium in that well was set, has changed since the date ofthe Background
Reports. This analysis will include the foUowmg
(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 Chlonde, Sulfate, Fluonde and Uranium since the date of the Background Reports
that may suggest a change in the behavior of that well since tiie date of the Background
Reports; and
(ll) A mass balance analysis that will evaluate the observed concentrations in light of the
concentrations in MiU tailings and the presence or absence of any moundmg 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 m the well; and
(iv) Evaluate the expected impact from any such decrease in pH on the concentration of
uranium m the well, based on currentiy available information
The foregoing analyses (both steps) will bc 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 m pH, then Denison will propose
changes to the GWCL for uranium m 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 m 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 WeUs with Intenm 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 weU, 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 intenm, 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.
42 3 Other Constituents and Wells
Table 3 sets out a constituent, TDS in MW-18, that does not faU within the other categories
considered m the above Section.s.
MW-18 IS far upgradient of the Mill site, and could not have been impacted by Mill activities.
Staustically significant rising trends in .some constituents in MW-18, such as sulfate, which is a
component of TDS, have been observed m the Background Reports as being consistent with
natural background values MW-18 was also analyzed m 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 oi 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
revi.sed GWCL for TDS in MW-18, which reflects these natural changes in background
As mentioned m Denison's June 13, 2011 response to the Notice, the Umted States
Environmental Protection Agency ("EPA") has recognized the need to update compliance limits
peiiodically to reflect changes to background conditions.
In 2009 guidance, EPA states'
"We recommend that other reviews of background also take place penodically.
These include the following situations.
• When periodically updattng background, say every 1-2 years
• When performing a 5-10 year permit review
During these reviews, all observations designated as background should bc evaluated
to ensure that they still adequately reflect current natural or baseline groundwater
conditions. In particular, the background samples should be mvestigated for
apparent ti-ends or outliers. Statistical outUers may need to be removed, especiaUy 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.)
hi that Guidance, EPA further states.
"5.3.4 UPDATINGWHENTRENDS 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
senes plot or applying Chapter 17 trend analyses. Should such trend data be
added to the existing background sample? Most detection monitonng tests
assume that background is stationary over time, with no discemible trends or
seasonal variation. A mild trend will probably make very littie difference,
especially if a Student-r or Wilcoxon rank-sum test between the existing and
8
candidate background data sets is non-significant. More severe or continuing
trends are likely to be flagged as SSIs by formal intrawell prediction linut or
control chart tests
With interwell tests, a stronger trend m the common upgradient background may
signify d change in natural groundwater quality across the aquifer or an
incomplete charactcnzation of the fuU range of background vanation 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 wUl 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 wiU also identify any further studies that tiie analysis
indicates should be performed, and will propose, for Executive Secretary review and approval, a
plan and schedule for completion ofany such additional studies
If further analysis is required after completion ofthe Source Assessment Report, Denison and the
Executive Secretary will agree on the .scope of lhat 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 IG 4(c)
of the Permit, will be prepared and submitted by Denison m 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 ttends
in some weUs and other factors, it cannot be assumed that consecutive exceedances of a
constituent in a monitoring weU 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 tiie MiU site, the Q2
2011 Consecutive Exceedance of TDS should be considered to represent natural variation m
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 tiiis Plan therefore is to
first determine if the recent exceedances of uranium m MW-25 arc the result of background
influences. If they are determined to be the result of background influences, tiien 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 recentiy thoroughly studied in the Background Reports and in
tiie University of Utah Smdy Both the Background Reports and the University of Utah Study
concluded that groundwater at tiie site has not been impacted by Mill operations. Both of those
studies also acknowledged that there are natural influences at play at the site tiiat have given nse
to increasing water trends and general variabiUty of background groundwater at the site.
It IS not practicable to redo those studies each time a monitoring well shows consecutive
exceedances, particularly where tiie exceedances are consistent with those recent analyses The
focus should therefore be on identifying any changes m the circumstances identified in those
studies
Based on tiie information available at this time, Denison believes tiiat tiie exceedances ob.served
are the result of natural influences and reflect the need to adjust some of the GWCLs for the site
10
Attachment C
DUSA Transmittal of Plan and Time Schedule under Utah Ground Water Discharge Permit UGW370004
Part I G 4(d), Apnl 13, 2012
PLAN TO INVESTIGATE
pH EXCEEDANCES IN PERCHED
GROUNDWATER MONITORING WELLS
WHITE MESA URANIUM MILL
BLANDING, UTAH
April 13. 2012
Prepared for
DENISON MINES (USA) CORP
1050 17th Street, Suite 950
Denver, Colorado 80265
Prepared by
HYDRO GEO CHEM, INC
51 WestWetmore Road, Suite lOt
Tucson, Anzona 85705
[phone]
Project Number 7180000 00-2 0
HYDRO GEO CHEM, INC.
Environmental Science <& Tec/inologf
PLAN TO INVESTIGATE
pH EXCEEDANCES IN PERCHED
GROUNDWATER MONITORING WELLS
WHITE MESA URANIUM MILL
BLANDING, UTAH
Piepaied foi
DENISON MINES (USA) CORP.
1050 17thStieet, Suite 950
Denver, Coloiado 80265
Piepared, Reviewed, and Approved by
^Q^t J^m^, UT fX}. No. 5336166-2250
AssocialSe-Hydrogeologist
Apnl 13,2012
TABLE OF CONTENTS
INTRODUCTION . 1
1 1 Purpose . 2
1 2 Previously Submitted Plans . 2
HISTORY 5
21 Summary of pH Activittes . . 5
2 2 Conclusions from the pH Data Analyses Conducted to Date . 6
2 3 Summary of Agreements and Acttons . 6
2 3 1 Denison Acttons 6
2 3.11 Existtng Wildhfe Ponds 6
2 3 12 Stattsttcal Analysis of pH Trends .. . .7
2 3 13 Assessments Outimed in the Plans and Schedules 7
2 3 14 Analysis of Pyrite at the Site 7
2 4 Regulatory Actions . 8
PH PLAN 9
3 1 Stattsttcal and Geochemical Evaluatton 9
3 1 1 Stattsttcal Analysis of pH Data 9
3 111 Linear Regression to Test for Trends . . 10
3 112 Data Exploratton 11
3 113 Updattng Compliance Limits 11
3 1 2 Geochemical Analysis of Wells with Significantty Declining pH 12
3 121 Analysis of Indicator Parameters 12
3 12 2 Mass Balance Analysis 13
3 123 Potenttal Transport Analysis .. 15
3 1.3 Reporting 15
3 2 Pynte Analysis Plan • 15
3 2 1 Background . . 16
3 2 2 Pynte Oxidatton as a Potenttal Mechanism for Decreasing pH .17
3 23 Rationale . . . 18
3 2 4 Samphng and Analytical Plan 19
3 25 Reporting . 21
LIMITATIONS 23
Plan to Investigate pH Exceedances in Perched i
Groundwater Monitonng Wells
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TABLE OF CONTENTS (Continued)
TABLES
1 Listtng of Groundwater Monitonng Wells Currentiy m Out-of-Compliance Status and
Groundwater Wells in Accelerated Monitoring
2 Tabulated pH Results from INTERA 2011 GWCL Evaluatton
3 Tabulation of Presence of Pyrite, Iron Oxide, and Carbonaceous Fragments in Dnll Logs
4 Samples to be Submitted for Visual Examinatton of Pynte
5 Samples to be Submitted for Laboratory Analysis of Pyrite
FIGURES
1 White Mesa Site Plan Showing Locattons of Perched Wells, Piezometers, and Borings
2 White Mesa Site Plan Showing Locations of Samples to be Visually Verified for Pynte
3 White Mesa Site Plan Showing Locations of Samples for Laboratory Analysis of Pyrite
APPENDICES
A Lithologic Logs
B Well Construction Diagrams
Plan to Investigate pH Exceedances m Perched n
Groundwater Monitonng Wells
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1. INTRODUCTION
This document presents the pH Plan and Time Schedule (pH Plan) to address dual exceedances
of pH m eleven perched groundwater monitonng wells at the White Mesa Mill (the Mill) and to
provide information related to the overall decline in groundwater pH that has been observed m
site wells Sections 1 and 2 were prepared primarily by Denison Mines (USA) Corp (Denison),
Section 3 1 was prepared pnmanly by INTERA, Inc (INTERA), and Section 3 2 was prepared
primarily by Hydro Geo Chem, Inc (HGC)
The eleven wells currentiy in out-of-compliance (OOC) status are listed in Table 1 The
Groundwater Discharge Pemut UGW370004 (GWDP), Part.I G 2 states that "out-of-compliance
status exists when the concenttation of a pollutant in two consecutive samples from a compliance
monitoring point exceeds a GWCL in Table 2 of this Permif The GWDP provides an
acceptance range for field pH GWCLs In all instances, the field pH measurements discussed
herein are slightiy below the lower limit of the GWCLs specified in the GWDP E-mail
correspondence from DRC dated March 13, 2012 provided a list of wells in OOC status that was
partially incorrect Table 1 lists the wells that are currentiy in OOC (as of 4'*^ Quarter 2011) and
the consecutive quarters in which those measurements were noted Table 1 also lists the
groundwater wells which are currentiy m accelerated monitoring for field pH measurements but
are not m OOC Accelerated monitoring would be the result of field pH excursions that are one-
time or non-consecutive measurements below the field pH GWCL The OOC status is limited to
those wells which have expenenced two consecutive monitoring penods outside the GWCLs
range
The decline in pH has been noted in perched wells located upgradient, cross-gradient, and
downgradient of the Mill and tailings cells This phenomenon may have any number of causes,
however, the widespread nature of the declining pH indicates that, whether recent or longer-term,
it results from a natural phenomenon unrelated to Mill operations
Reference is made to the following previously submitted documents
• Plan and Time Schedule Under Part IG 4(d) for Violations of Part IG 2 for Constituents
in the First, Second, Third and Fourth Quarters of 2010 and First Quarter of 2011 dated
June 13, 2011 (Initial Plan and Schedule),
• Plan and Time Schedule Under Part 1G 4(d) for Violations of Part IG2for Constituents
in the Second Quarter of 2011 dated September 7, 2011 (Q2 2011 Plan and Schedule),
and
Plan to Investigate pH Exceedances m Perched 1
Groundwater Monitonng Wells
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Apnl 13,2012
• Letter dated January 20, 2012 regarding the Plan and Time schedule Under Utah
Groundwater Discharge Permit UGW370004 Part 1G 4(d)
• Revised Background Groundwater Quality Report Existing Wells For Demson Mines
(USA) Corp 's MiU Site, San Juan County, Utah October 2007, (Existing Wells
Background Report)
• 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 (Regional Background Report)
• Revised Background Groundwater Quality Report New Wells for Denison Mines (USA)
Corp's White Mesa Uranium Mill, San Juan County, Utah Published in Apnl, 2008
prepared by INTERA, Inc (New Wells Background Report)
The latter three reports are collectively referred to as the "Background Reports"
Dunng conference calls held on December 5, December 19, 2011, and March 12, 2012 Utah
Division of Radiation Conttol (DRC) staff discussed issues related to pH and the Denison actions
necessary to address DRC's concems
This document sets out the Plan and Schedule to address the issues related to pH at the Mill site
that was agreed upon in principle dunng those conference calls
1.1 Purpose
The purpose of this pH Plan is to describe the activities that will be completed by Denison to
address the eleven wells in OOC status for pH and to determine whether the decline in pH in the
perched groundwater at the Mill is the result of a natural phenomenon unrelated to Mill
operations
1.2 Previously Submitted Plans
As noted above, Denison has submitted two Plans (the Initial Plan and Schedule and the Q2 2011
Plan and Schedule) to address analytes other than pH in OOC status Those plans were submitted
June 13, and September 7, 2011
The assessments for OOC constituents other than pH, proposed by Denison and described in
Section 4 of the Initial Plan and Schedule and Section 4 of the Q2 2011 Plan and Schedule, will
continue to be performed as proposed and in the timeframes set out in those Plans and Schedules
Plan to Investigate pH Exceedances m Perched 2
Groundwater Monitonng Wells
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Apnl 13. 2012
Those assessments are intended to determine if the exceedances in question are due to
background influences or Mill activities If the exceedances are detenmned to be due to
background influences then, as contemplated by those Plans and Schedules and this pH Plan, it
will not be necessary to perform any further evaluations on the extent and potential dispersion of
the contamination or to perform any evaluation of potential remedial actions Monitonng will
continue and, if appropnate, revised groundwater compliance limits (GWCLs) will be proposed
to reflect changes in background conditions at the site Specifics related to these assessments are
discussed in the respective plans referenced above Similar logic applies to the GWCLs for pH at
the site
Plan to Investigate pH Exceedances in Perched 3
Groundwater Monitonng Wells
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Plan to Investigate pH Exceedances in Perched 4
Groundwater Monitonng Wells
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2. HISTORY
A bnef discussion of the history and previous activities is provided in Sections 2 1 and 2 2
2.1 Summary of pH Activities
Dunng the completion of the 4^*^ Quarter 2010 Quarterly Groundwater Monitonng Report,
Denison noted eleven perched groundwater monitoring wells with pH measurements below the
GWCLs These wells are located upgradient, cross-gradient, and downgradient of the Mill and
tailings cells Investigation into the eleven pH GWCLs m question indicated that the GWCLs for
groundwater pH in all wells established in the January 20, 2010 GWDP were erroneously based
on historic laboratory results instead of field measurements as contemplated by Table 2 of the
GWDP Denison notified DRC in a letter dated Febmary 1, 2011 that the existtng GWCLs for
groundwater pH were inconectiy based on laboratory results rather than field measurements and
proposed to submit revised descnpttve statistics for field pH to be used as revised pH GWCLs by
the end of the second quarter 2011
Denison received approval from DRC by e-mail on Febmary 14, 2011 to proceed with the
revision of the pH GWCLs based on field measurements Denison's geochemical consultant,
INTERA, Inc , completed the data processing and statistical assessments necessary to revise the
GWCLs based on historic field pH data The data processing and statistical assessments
completed by INTERA were based on the DRC-approved methods in the logic flow diagram
included as Figure 17 of the New Wells Background Report Following the statistical evaluation
of pH data by INTERA, Denison compared the Mill's groundwater pH data from the 2nd
Quarter of 2011, including accelerated sampling results through June 2011, and noted that all of
the June 2011 groundwater results, and many of the other results from the 2"^* Quarter, were
already 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 ttend of decreasing pH, which was addressed in the
Background Study Reports, appeared to be present in nearly all wells throughout the Mill site
area, including upgradient, downgradient, and cross-gradient wells in the groundwater
monitoring program Table 2 presents a summary of the results of the statistical evaluation of
groundwater pH data performed by INTERA in June 2011 As shown m Table 2, as of June
2011, all groundwater monitoring (MW-series) wells demonsttated a downward ttend m the field
pH data over time
Denison notified DRC on June 28, 2011 by telephone and by follow-up letter dated June 30,
2011 that the 2"^* Quarter 2011 data exceeded the recalculated GWCLs Denison advised DRC
Plan to Investigate pH Exceedances in Perched 5
Groundwater Monitonng Wells
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that, as a result of these findings, Denison did not believe it was appropnate to conttnue with its
efforts to reset die GWCLs for pH based on field pH data, as onginally planned, but instead it
appeared that it would be more appropriate to undertake a study to detemune whether the
decreasing ttends in PH are due to namral influences and, if so, to detemune a more appropnate
way to determine GWCLs Addittonally, Denison requested the opportunity for a meettng with
DRC to discuss Denison's findings to date and to agree upon any further investtgations to be
completed, as well as to agree upon the steps and milestone dates to be incorporated in the pH
Plan The meetings with DRC were conducted via teleconference on December 5, and December
19, 2011 These teleconferences resulted in the January 20, 2012 letter and this revised pH Plan
A subsequent teleconference on March 12, 2012 led to the development of this pH Plan
2.2 Conclusions from the pH Data Analyses Conducted to Date
The pnmary conclusion from the activities conducted to date is that the histoncal ttend 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 cross-
gradient wells in the groundwater monitoring program, and there seems to be no abatement of
the ttend The wide-spread nature of tiie decrease in pH in upgradient, downgradient and cross-
gradient wells, suggests that the pH decrease results from a natural phenomenon unrelated to
Mill operations
2.3 Summary of Agreements and Actions
The following is a summary list of agreements and actions which resulted from the discussion
with DRC in teleconferences on December 5, December 19, 2011 and March 12, 2012
2 3 1 Denison Actions
23 11 Existing Wildlife Ponds
DRC and Denison acknowledge that recharging the existing wildlife ponds at the site may be
adding oxygen to the groundwater, which, on tiie assumption that sufficient pynte exists in the
formation, may contnbute to the decreasing ttends in pH at the site, and to exceedances of
certain metals m wells possibly as a result of decreases in pH
The Mill has therefore agreed to stop recharging both upper wildlife ponds immediately No
actions to prevent natural accumulation of water will be taken However, the ponds are not
designed to gather precipitation from the local drainages, so the net evaporation rate should
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Groundwater Monitonng Wells
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ensure that the ponds do not accumulate any significant precipitation Recharge at the two upper
wildlife ponds would not resume without approval of the Executive Secretary
The Mill will continue to recharge the lower wildlife pond (Dutch's Bayou)
DRC and Denison acknowledge that stopping the recharge of the two upper wildlife ponds is
expected to affect the perched water quality and water levels over time, which could result in the
need to reset GWCLs at the site
23 12 Statistical Analysis ofpH Trends
Denison will provide to DRC a statistical analysis of pH in all wells at the Mill site, which will
quantify the decreasing trends in pH at the site as a whole, and indicate which monitoring wells
have significant decreasing ttends in pH The analyses are discussed m detail in Section 3 1 In
performing this statistical analysis, Denison will follow the Groundwater Data Preparation and
Statistical Process Flow for Calculating Groundwater Protection Standards, White Mesa Mill
Site, San Juan County, Utah, included as Figure 17 in the New Wells Background Report This
statistical analysis report will be submitted to the Executive Secretary withm 90 days after
execution and delivery of a Stipulated Consent Agreement (the "Stipulated Consent Agreement")
relating to the implementation of this pH Plan
2.3 1 3 Assessments Outlined in the Plans and Schedules
The assessments proposed by Denison and described in Section 4 of the Initial Plan and
Schedule and Section 4 of the Q2 2011 Plan and Schedule for OOC constituents except pH, will
continue to be performed as proposed and in the timeframes set out in those Plans and Schedules
In addition, the statistical analysis of indicator parameters discussed in Section 3 12 1 below will
also be performed in all wells that have one or more OOC constituents and for which such
analysis is not otherwise being performed under Section 3 12 1.
23 14 Analysis of Pyrite at the Site
The site-wide decline of pH is occumng in perched wells cross-gradient, upgradient, and
downgradient of the Mill suggesting that the potential causes are not related to Mill operation
Potential causes of the site-wide decline of pH may be the result of physical interactions,
geochenucal phenomenon, natural processes, or some combination of all of these factors
Physical interactions such as over-pumping, over-developing, increased sample frequency and
the associated increased purging of the perched wells may be contributing factors A
geochemical phenomenon (such as the oxidation of pyrite) is a potential mechanism for the
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Groundwater Monitonng Wells
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decline in pH and could be enhanced by increased oxygen ttansport resulting from the physical
interactions listed above Natural processes such as drought conditions which may increase the
rate of oxygen ttansport in the vadose zone may also be conttibuting factors Although not
necessarily the only or primary cause, the oxidation of pynte (or other sulfides) is expected to
occur site-wide, because pynte has been noted in borings across the entire site (including bonngs
located upgradient, cross-gradient, and downgradient of the Mill and tailings cells) Regardless
of the outcome of the pyrite investigation specified in this pH Plan, it appears that the pH decline
is a site-wide phenomenon resulting from one or more non-Mill related factors
This pH Plan describes the activities that will be conducted to venfy the presence of pynte as
one of the possible causes of the decrease in pH in perched groundwater at the Mill In summary,
the presence of pynte will be verified using screening, visual and analytical methods
A report will be prepared that summarizes the sample selection and submission process, the
methods employed, and the results The report will include an assessment of the results with
regard to the potential for pyrite oxidation to affect pH at site perched monitoring wells This
report will be subnutted to the Executtve Secretary withm 120 days after execution and delivery
of the Stipulated Consent Agreement
A detailed descnption of the pynte investigation is included in Section 3 2 of this pH Plan
Regardless of the results of the pynte verification study, however, the pH data to date indicate
that the pH decline is a site-wide phenomenon and that if oxidation of pynte or other sulfides is
not the cause, then another, natural, site-wide phenomenon must be the cause
2.4 Regulatory Actions
The January 20, 2012 letter was discussed with DRC in a teleconference on March 12, 2012, and
It was agreed that the commitments by Denison and DRC referred to in that letter and the
implementation of this pH Plan will be incorporated into the Stipulated Consent Agreement
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3. PHPLAN
The pH plan consists of a statistical and geochemical evaluation and a plan to verify the presence
of pyrite as discussed m the following Sections
3.1 Statistical and Geochemical Evaluation
As discussed in Section 2 1, Denison has been aware of the site wide decline in pH trends for
some time The New Wells Background Report stated
"on a review of the pH time plots in all existing wells (see Appendix D of the
Background Report), there appears to be a general decreasing trend in pH in all
wells Figure 18 shows results of linear regression analyses for all site
monitoring wells over the same time period used for new wells Regression lines
trend downward in all site monitoring wells and among the existing wells the
trends are statistically sigmficant in MW-3, MW-12, MW-14 and MW-17 The fact
that pH IS trending downward in all site monitormg wells indicates that
statistically significant decreasing trends in pH m MW-25, MW-27, MW-28, and
MW-3A are not related to any potential tailings seepage impacts Instead there is
a systematic process occurring that affects the site as a whole This process may
be a natural phenomenon related to regional changes or it could be some
systematic change in the way that samples are collected or analyzed "
In INTERA's response to the URS Memorandum Completeness Review for the Revised
Background Groundwater Quality Report' Existing Wells for Demson Mines (USA) Corp's
White Mesa Mill Site, San Juan County, Utah, dated July 2, 2008, INTERA predicted that pH in
some wells could fall below GWCLs if methods of calculating GWCLs for pH were not
modified At this time, Denison proposes to perform a statistical analysis of pH in data collected
from monitor wells across the site and a geochemical analysis of indicator parameters in the 11
pH wells in question in order to obtain a more complete and up to date understanding of pH
trends across the site and any potential relationship to mill operations
3 1 1 Statistical Analysis of pH Data
Demson will perform a statistical analysis of pH data from all perched monitor wells at the site
for which at least eight rounds of data are available in accordance with statistical methods
described in the Existing Wells Background Report A test for ttends will be particularly
important and will be conducted in accordance with Section 6 (Testing for Trends and
Calculating the GWCL) of the Existing Wells Background Report
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3 1.1 1 Linear Regression to Test for Trends
As there are no no-detect values in pH data, linear regression is the best test for normally or log-
normally disttibuted data The conelatton coefficient (R) represents the linear relattonship
between two vanables R Square (R^) shows how closely X and Y are related By taking the
square of the R value, all values of R^ are positive (values of R can range from - I to -Hi), and fall
between 0 (no correlation) and 1 (perfect conelation) The R^ value is a measure of the sttength
of the predictive capability of the regression line An R^ value of 0 indicates that the regression
line has no predictive ability at all An R^ value of 1 indicates that the regression line fits the data
perfectiy and, therefore, has the highest possible predictive capability Generally, an R^ value
less than 0 5 is considered to be a poor correlation, and the linear regression line is not
considered to be a reliable representation of the data (i e , it explains less than half of the data)
The significance of a correlation coefficient of a particular sttength or fit will change depending
on the size of the sample from which it was computed In this document, linear regression ttends
are considered to be statistically-significant if there are enough data points to make a
determination and enough of those points fall within the calculated variance of the data set Least
squares regression analysis of the data will be performed m order to determine whether the
association between the variables is statistically significant at the 95 percent level
The statistical significance (p-level) of a result is an estimated measure of the degree to which it
IS "tme" (in the sense of "representative of the population") More technically, the value of the p-
level represents a decreasing index of the reliability of a result The higher the p-level, the less
we can believe that the observed relation between variables in the sample is a reliable indicator
of the relation between the respective vanables in the population Specifically, the p-level
represents the probability of error that is involved in accepting our observed result as valid, that
IS, as "representative of the population " For example, the p-level of 05 (i e ,1/20) indicates that
there is a 5 percent probability that the relation between the variables found in our sample is a
"fluke " In other words, assuming that m the population there was no relation between those
vanables whatsoever, and we were repeating experiments like ours one after another, we could
expect that m approximately every 20 replications of the expenment there would be one m which
the relation between the vanables in question would be equal or sttonger than in ours In many
areas of research, the p-level of 05 is customarily tteated as a "border-line acceptable" error
level (StatSoft, Inc, 2005 STATISTICA [data analysis software system], version 7 1
www statsoft com)
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3 112 Data Exploration
Some monitor wells at the site have data extending from 1979 to the present while others have
barely eight recent data rounds To date, decreasing pH ttends have been observed most sttongly
in data collected from 2005 to the present Therefore, Denison proposes to explore data sets to
ascertain if there are any parttcular time periods during which pH data have shown a site wide
decline and if such declines have happened in the past If such declines have happened in the past
or if they can be tted to a parttcular penod, it may provide evidence for a process or cause of the
declines
3 113 Updating Compliance Limits
As menttoned in Denison's June 13, 2011 response to the Notice of Violation and Compliance
Order, Docket No UGW 11-02, the United States Environmental Protectton Agency (EPA) has
recognized the need to update compliance limits periodically to reflect changes to background
condittons
As stated in EPA 530/R-09-007, March 2009 Statistical Analysis Of Groundwater Monitormg
Data At RCRA Facilities Unified Guidance, Environmental Protectton Agency, Office Of
Resource Conservation And Recovery
"We recommend that other reviews of background also take place periodically
These include thefollowing 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
mvestigated 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 "
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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 applymg 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-t or Wilcoxon rank-sum test between the existmg and candidate
background data sets is nonsignificant 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 ^ change in natural groundwater quality across the aquifer or an
incomplete characterization ofthe 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 "
3 1 2 Geochemical Analysis of Wells with Sianificantiv Declining pH
If the pH trend data from a monitor well is determined to be statistically significant, a
geochemical analysis will be performed to determine if the declining pH ttends can be related to
potenttal mill processes The geochemical analysis will consist of
• an analysis of indicator parameters,
• a mass balance analysis, and
• an analysis of potenttal for ttansport
3 12 1 Analysis of Indicator Parameters
Seepage from the tailings impoundments would be indicated by nsing concenttattons of chlonde,
sulfate, fluonde, and uranium because 1) these constttuents are abundant in tailings wastewater
(see Table 15 of the Revised Background Report), and 2) these constttuents are relattvely mobile
and conservattve in the groundwater environment In contrast, many other constituents are either
not present in relatively high concentrations in tailings wastewater and/or are reactive in the
subsurface environment Denison will prepare time concenttation plots of these four parameters
from data taken from all monitor wells on site that have one or more OOCs, includmg OOCs for
pH (where such indicator parameter data is available) to determine if there is evidence that
concentrations of any of the OOC parameters can be related to potential mill processes
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Regression or Mann Kendall analysis will be performed to determine if any such indicator
parameter has a significant upward trend If a monitor well has a significant upward ttend m
some, but not all, indicator parameters, then a further analysis will be performed to determine
whether or not the increasing trends can be related to potenttal mill processes
3 122 Mass Balance Analysis
After the analysis of indicator parameters, if any indicator parameter shows a significant upward
ttend, a mass balance calculatton will also be performed to determine if there is evidence that
concenttattons can be related to potenttal mill processes It is possible to esttmate the mass of
each indicator parameter in the groundwater beneath the rmllsite by assuming a saturated
thickness of groundwater in the aquifer matnx, a porosity of the aquifer mattix, an average
concenttatton of constituents in groundwater, and an area to which the average concentratton
applies Any potential source of indicator parameters will be evaluated to detemune if it has the
potenttal to have caused the mass of the indicator observed in the groundwater beneath the Mill
site First, the potenttal source must have a means to reach groundwater such as sufficient water
or other fluid to ttavel through the vadose zone Second there must have been sufficient
concenttattons of the indicator parameter m the source to account for the mass of indicator
parameter observed in the groundwater Both conditions can be evaluated by mass balance
calculattons
An example of a mass balance calculatton was presented in INTERA, Inc 2009 Nitrate
Contamination Investigation Report, White Mesa Uranium Mill Site, Blanding Utah, where one
of the suggested possibilities was a groundwater mound from the tailings cells that might cause
elevated nittate and chlonde concenttations upgradient in the area of the nittate and chlonde
plume A calculation for nittate to evaluate this possibility (a calculation for chloride would be
similar) suggests that on the order of eleven percent tailings solution (assuming the highest
recentiy observed nittate concenttatton in the tailings of 290 mg/L) would have to mix with
unimpacted groundwater (assunung 1 mg/L) in order to account for the observed mass of nittate
in groundwater, assuming an average nitrate concenttatton in the plume above the 20 mg/L
isopleth of 30 mg/L The details of this example calculatton based on nittate are provided below
The size of the nittate plume above 20 mg/L is approximately 40 acres, or approximately
1,740,000 square feet in map area Assuming 45 feet of saturated thickness (based on Hydro Geo
Chem, Inc 2007 Preliminary Contammation Investigation Report White Mesa Uranium Mill
Site Near Blandmg, Utah November 20, 2007) and a porosity of 0 2, there are approximately
15,700,000 cubic feet or 117,000,000 gallons of groundwater in that area Eleven percent of that
IS approximately 12,900,000 gallons (approximately 40 acre feet) which is a conservattve
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esttmate of the volume of tailings solutton that would have to be mixed with groundwater to
account for the mass of nitrate in the portion of the plume above 20 mg/L nitrate The following
calculattons support these esttmates
Assume
• Nittate Concenttatton m Tailings Solutton 290 mg/L
• Nittate Concenttatton in un-impacted Groundwater 1 mg/L
• Average Plume Concenttatton 30 mg/L
Mixing Equatton Ct*Vt + Cg*Vg = Cm*Vm (eql)
Where Ct = Concenttatton of nittate in tailings soluttons
Vt = Volume of tailings soluttons
Cg = Concenttatton of nittate in unimpacted groundwater
Vg = Volume of unimpacted groundwater
Cm = Concenttatton of nitrate in nuxture of groundwater and tailings soluttons
Vm = Volume of mixture of groundwater and tailmgs soluttons
Another Equatton Vt + Vg = Vm (eq2)
Substttuttng eq2 in eql Ct*Vt + Cg*Vg = Cm* (Vt + Vg) (eq3)
Substttute Nittate Concenttattons m eq3
290* Vt + l*Vg = 30*(Vt + Vg)
290* Vt + l*Vg = 30* Vt + 30* Vg
260*Vt = 29*Vg
Vt = 29/260*Vg = 0 ll*Vg
Based on the above, the volume of tailings solutton would have to be approximately eleven
percent of the volume of un-impacted groundwater in the mixture
The above mass balance is an example of calculattons that would be prepared for, and the
reasoning that would be applied to, indicator parameters in data from wells that are OOC for pH,
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if those wells have nsing ttends in the indicator parameters In the case of the indicator
parameters their concenttations would be used instead of nittate m the above equatton(s) These
calculations would provide one line of evidence to test the possibility that any potenttal nsing
ttend m indicator parameters and the decreasing pH (in wells that are OOC for pH) could or
could not be related to mill operattons
3 123 Potential Transport Analysis
In cases where data from OOC wells that have stattsttcally significant decreasing pH trends and
increasing indicator ttends, are distant from the Mill's tailings cells, a ttansport analysis will be
performed to determine the plausibility of impact from mill related processes The transport
analysis will consider the geochemical ttansport properttes of each indicator parameter with a
significantty increasing trend and an analyttcal calculatton of potenttal ttavel ttmes to the well
from potenttal mill related sources will be performed to determine if there is evidence that the
indicator parameter could plausibly have amved at the well dunng the life of the mill
3 1 3 Reporting
The Statisttcal and Geochemical Evaluatton Report will detail the results of all of the analysis to
be performed and the conclusions to be drawn from such analyses Denison will work with DRC
to reset GWCLs to properly reflect the decreasing pH trends The report will also identify any
further studies that the analysis indicates should be performed, and will propose, for Executtve
Secretary review and approval, a plan and schedule for completton of any such addittonal
studies
If further analysis is required after completion of the Stattsttcal and Geochemical Evaluatton
Report, Demson and the Executtve Secretary will agree on the scope of that analysis, based on
the findings in the report, including any further reports that will need to be prepared The report
will be submitted to the Executtve Secretary withm 90 days after execution and delivery of the
Stipulated Consent Agreement
3.2 Pyrite Analysis Plan
As discussed in Section 2 3 14, oxidation of pyrite (or other sulfides) is a potential cause of the
site-wide decline in pH Pynte has been noted in the majority of the borings at the site having
detailed lithologic logs (including borings located upgradient, cross-gradient, and downgradient
of the miUsite and tailings cells) The occurrence of the declining pH ttend over the entire site
indicates that the trend is not the result of site operattons Otherwise the decreases in pH would
occur pnmanly within the area of the millsite and tailings cells
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Although pynte has not been noted in every bonng at the site having a detailed lithologic log, it
has been noted in sufficient borings for pynte oxidation to be considered a plausible mechanism
for decreasing pH The lack of visually detected pynte in the lithologic log of any specific boring
does not necessarily indicate that pynte is not present in or near that bonng nor that pyrite is not
present in close enough proximity to that boring to influence pH in the well completed in that
boring Verificatton of the pynte noted in existtng drill cutttngs samples from a subset of borings
installed across the enttre site is considered sufficient to demonsttate the site-wide occurrence of
pynte and to support the oxidatton of pynte (or other sulfides) as one plausible mechanism for
the decreasing pH
The purpose of the Pynte Analysis Plan is therefore to venfy the presence of pynte as one of the
possible causes of the decrease in pH Existtng drill cutttngs and/or core samples stored at the
site will be used for this purpose The data quality objecttves are as follows
1 To verify the existence of pyrite reported in existtng boring logs from a sample of site
bonngs The sample will include borings located across the enttre site (upgradient, cross-
gradient and downgradient of the millsite and tailings cells)
2 To verify the existence of and analyze for pyrite in MW-series wells which are in
accelerated monitonng for pH or OOC for pH and which have drill cutttngs and/or core
stored onsite
3 2 1 Background
The 97 perched monitoring wells, temporary perched monitoring wells, and piezometers shown
in Figure 1 are screened in a relattvely shallow perched water zone hosted primarily by the Burro
Canyon Formatton Where saturated thicknesses are greater, the perched water rises into the
overlying Dakota Sandstone The Burro Canyon is underlain by the Bmshy Basin Member of the
Momson Formatton, a bentonittc shale that essenttally forms the base of the perched water zone
The permeability of the Burro Canyon is generally low, with a geometnc average hydraulic
conducttvity on the order of 10'^ centtmeters per second (cm/s), but with a range of
approximately 10'^ cm/s to 10'^ cm/s
Lithologic logs reveal that iron oxides and pyrite are common within the Buno Canyon and
overlying Dakota Many of the logs indicate the presence of carbonaceous fragments consistent
with reduced condittons and the presence of pyrite The iron oxides present in many of the
bonngs may result from oxidizatton of pynte or other sulfides
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Table 3 indicates the presence of visible pynte, iron oxides, and carbonaceous material from
bonngs at the site for which detailed and moderately detailed logs are available Logs for many
of the older wells at the site (MW-1 through MW-15) are not detailed enough to contain this
informatton and are not included in Table 3 Logs for wells MW-16 through MW-22 are only
moderately detailed Logs for wells MW-3A, MW-23 through MW-37, temporary wells (TW4-
series and TWN-senes wells), and piezometers (PIEZ-senes and DR-series) contain the most
detail Temporary wells and piezometers are included in Table 3 because many of these wells are
in the vicinity of MW-senes wells lacking detailed logs (for example, upgradient well MW-1)
and they demonsttate the site-wide occurrence of pyrite
Lithologic logs for all bonngs at the site having detailed logs (MW-3A, MW-23 through MW-
37, temporary wells (TW4-senes and TWN-senes wells), and piezometers [PIEZ-senes and DR-
senes]) are provided in Appendix A Pyrite has been noted in approximately ^1^ of the bonngs
having detailed lithologic logs
3 2 2 Pynte Oxidation as a Potential Mechanism for Decreasing pH
Oxidatton of pyrite is one potenttal mechanism for the decreasing pH measured in perched zone
wells Pynte oxidizes in the presence of oxygen according to the following equation, producing
hydrogen ions and sulfate in the process
2FeS2 + 7O2 + 2H2O = 2Fe^^ + 4S04^- + 4H"' (eq4)
This IS the same mechanism that results in acidic drainage from mine tailings or waste rock piles
containing pynte. Oxygen ttansported into the piles reacts with the pynte (in the presence of
water) releasing acid and sulfate
The widespread occurrence of visible pynte in the Burro Canyon Formation (upgradient, cross-
gradient, and downgradient of the rmllsite and tailings cells) makes this mechanism plausible
Sources of oxygen include 1) diffusion through the vadose zone aided by the generally dry
conditton of the vadose zone and barometric pumping 2) ttansport of oxygen from the surface
directiy to the formatton via perched monitoring well casings, and 3) mfilttatton of water
containing dissolved oxygen Significant sources of mfiltrattng water containing oxygen include
the wildlife ponds as discussed in Sectton 2 3 11 Oxygen ttansport m the vicinity of perched
wells is expected to be enhanced by fluctuations in the perched water table caused by routine
purging and sampling, the recent redevelopment effort, and changes in pumping Changes in
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purging and sampling methodology and frequency are also expected to impact oxygen transport
to perched water
A low rate of pynte oxidatton is likely tabng place over the enttre site due to diffusion of oxygen
through the vadose zone and via oxygen dissolved in recharge However, the rates are likely
much larger in the vicinity of the perched zone wells where the well casings are a direct conduit
for oxygen transport to the groundwater With each well casing acttng as a constant source of
oxygen directiy to groundwater, gradually expanding volumes of the perched zone near each
well are expected to be impacted over ttme as oxygen spreads out, more pynte is oxidized, and
any neuttalizatton capacity in the formatton is consumed
323 Rationale
Although pynte has been noted in approximately ^Iz of the bonngs having detailed lithologic
logs, the DRC has requested verificatton of pyrite occunence before considenng oxidatton of
pynte as a potenttal mechanism for decreasing pH
Dnll cutttngs and core samples from the installatton of numerous perched monitoring wells and
borings have been collected, labeled as to the borehole name/number and depth interval, and
stored on-site Pyrite present m these existtng samples is expected to have undergone small to
negligible degradatton since collectton Use of existtng samples in the venficatton process is
therefore considered acceptable
Pyrite has been detected visually in drill cutttngs from the site since at least 1999 Visual
detectton of pynte in a parttcular sample suggests that the volumetnc content of pyrite in the
sample is at least 0 1% Notattons in the logs indicate volumetnc pynte contents may be as high
as three percent in some intervals Visual re-exammatton by an expenenced geologist or
mineralogist of drill cutttngs samples previously identtfied as having pynte is considered
sufficient to venfy the presence of pynte As an additional measure, laboratory analysis of pynte
IS also proposed as discussed below
The presence of visually detectable pyrite in a sample would increase the sulfur and iron contents
of that sample and yield total iron and sulfur concenttattons that are expected to be nottceably
higher than samples without visually detectable pynte, assuming all other condittons equal
Analysis of total iron and sulfur would likely identtfy samples with pyrite However, gypsum has
also been identtfied m drill cutttngs from the site and gypsum would conttibute to the total sulfur
analytical result Furthermore, high iron content could result from high concenttations of iron
oxide minerals which may or may not be indicative of oxidized pyrite Therefore, analysis of
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samples for total iron and sulfur would likely yield results that are ambiguous with respect to
pyrite content
Using an analytical method specific to pyrite is expected to yield more conclusive results
Scanning election microscopy coupled with energy dispersive x-ray analysis is one method
capable of detecttng pynte
3 2 4 Sampling and Analytical Plan
Venfication of the presence of pynte will be accomplished using visual and analytical methods
Visual verificatton will rely on exanunatton of samples by an expenenced geologist or
rmneralogist other than the geologist(s) who onginally logged the borings Analyttcal
venfication will rely on laboratory analysis of selected samples for pyrite and other sulfides The
locattons of bonngs from which samples are to be submitted for visual or laboratory
identtficatton of pyrite, respecttvely, are provided in Figures 2 and 3 The sample set provides
site-wide coverage
Since 1999 drill cutttngs samples were typically collected at 2 V2 foot deptii intervals and stored
in zip-seal bags labeled with the bonng identtficatton (ID) and the depth interval Smaller
samples of the dnll cutttngs were typically washed and stored in plastic cutttngs boxes labeled
with the borehole ID and having each sample compartment labeled with the depth interval When
collected, core samples were logged conttnuously except for intervals where core recovery was
not possible Drill core was stored m cardboard core boxes labeled with the borehole ID and
depth interval represented in each box
Samples to be subnutted for visual venficatton are provided in Table 4 All borings listed in
Table 4 had pynte noted in the drilling logs Visual venficatton will rely on examinatton of drill
cutttngs and/or core samples from selected depth intervals where pyrite was noted m the drilling
logs The depth intervals will be within the screened intervals of borings completed as wells
Appendix B contains well completion diagrams for all wells listed in Table 4 Samples listed m
Table 4 were collected from bonngs installed since 2002 that were upgradient, cross-gradient
and downgradient of the tailings cells (Figure 2) Bonngs listed in Table 4 include TWN-19 (the
most upgradient boring at the site) and DR-25 (the most downgradient boring at the site
Samples submitted for visual venficatton will consist of zip sealed bags of cutttngs from the
desired borings and depth intervals These samples will be submitted to an expenenced geologist
or mineralogist for verification of 1) the presence of, 2) estimated abundance of, and 3) the
estimated grain sizes of pynte (or other visible sulfides) in each sample Visual examinatton will
include microscopic examination to ensure that pynte too fine-grained to have been identified
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during the logging procedure will be detected A blank sample consisting of "play sand" placed
in a zip seal bag and labeled similarly to the cuttings samples will also be submitted for visual
analysis
Samples to be subnutted for laboratory analysis are provided in Table 5 Table 5 includes all
MW-senes wells under accelerated monitonng with declining pH for which cutttngs or core
samples are available Not all bonngs listed in Table 5 had pyrite noted in the drilling logs
Samples subnutted for laboratory analysis will consist of zip sealed bags of cutttngs from the
desired bonngs and depth intervals and subsamples of core from the desired bonngs and depth
intervals, All submitted samples will be from depth intervals within the screened intervals of the
wells Appendix B contains well completton diagrams for all wells listed in Table 5 Analytical
venfication will rely on laboratory analysis for pynte via scanning electron microscopy coupled
with energy dispersive x-ray analysis or another method that is capable of quanttfying sulfides
Pynte was not noted in tiie detailed dnlling logs for MW-3 A, MW-23, MW-24, MW-28, and
MW-29, all of which are OOC for pH Samples from these borings will be selected for
laboratory analysis based on a field screening procedure Existtng cutttngs and/or core samples
from these borings will be screened visually and for iron and sulfur using a portable XRF The
XRF will be used in accordance with manufacturer's insttncttons All samples from the screened
depth intervals of the wells (Table 5) will be tested
The results of the visual exanunatton and the XRF screening will be documented in the field
notebook Documentatton will include the sample color, whether or not pynte was visible, and
the results of the XRF scan with respect to iron and sulfur
At least one sample from the screened depth interval of each boring will be submitted for
laboratory analysis If one or more samples from a particular boring have visually identtfiable
pynte (presumably missed dunng the original logging procedure) at least one of those samples
will be submitted for analysis If the XRF screening is unsuccessful at identtfying a sample from
a parttcular bonng having both iron and sulfur anomalies (and visual pynte is not present), at
least one sample will be selected for analysis based on color A grayish or greenish color
consistent with reduced condittons will be considered favorable for pyrite occunence
Each bagged cuttings or core sample selected for laboratory analysis will be photographed Any
core selected for analysis will be photographed withm the core box pnor to bagging Cuttings
selected for analysis will be photographed within the cutting storage box or zip-sealed bag The
depth interval wntten on the bag or cuttings storage box must be visible m the photograph
Plan to Investigate pH Exceedances in Perched 20
Groundwater Monitonng Wells
H \718000\pHdecrease\aprl2revision\pH Plan Exceedances m Perched GWM Wells Final doc
Apnl 13,2012
Cuttings samples submitted for either visual or laboratory analysis will consist of the entire
bagged cuttings sample Subsamples from the existing bagged samples will not be submitted
because of the likelihood that subsamples may not be representative due to pynte having settied
out in the original sample bags If the onginal sample bag has detenorated, the enttre onginal bag
will be placed inside a new labeled bag and submitted for analysis A blank sample consisttng of
"play sand" placed in a zip seal bag and labeled similarly to the cutttngs samples will also be
submitted for laboratory analysis The laboratory will be instmcted to retum unused sample
matenal to the site withm the original bags
Core samples subnutted for either visual or laboratory analysis will consist of subsamples of the
core from the desired depth interval and placed in zip-sealed bags labeled with the boring
number and the depth interval The laboratory will be instmcted to retum unused sample material
to the site withm the original bags
3 2 5 Reporting
A report will be prepared that descnbes the screening, selectton, and submission of samples, the
results of the sample screening process, and the visual and analyttcal methods employed The
report will provide the visual and analyttcal results and will include an assessment of the results
with regard to the potenttal for pyrite oxidatton to affect pH at site perched monitonng wells
This report will be submitted to the Executtve Secretary withm 120 days after execution and
delivery of the Stipulated Consent Agreement
Plan to Investigate pH Exceedances in Perched 21
Groundwater Monitonng Wells
H \718000\pHdecrease\aprl2revision\pH Plan Exceedances in Perched GWM Wells Final doc
Apnl 13,2012
Plan to Investigate pH Exceedances in Perched 22
Groundwater Monitonng Wells
H \718000\pHdecrease\aprl2revision\pH Plan Exceedances in Perched GWM Wells Final doc
Apnl 13,2012
4. LIMITATIONS
The information and any opinions, recommendations, and/or conclusions presented in this report
are based upon the scope of services and information obtained through the performance of the
services, as agreed upon by HGC and the party for whom this report was originally prepared
Results of any investigations, tests, or findings presented in this report apply solely to conditions
existing at the time HGC's investigative work was performed and are inherentiy based on and
lirmted to the available data and the extent of the investigation activities No representation,
warranty, or guarantee, express or implied, is intended or given HGC makes no representation as
to the accuracy or completeness of any information provided by other parties not under conttact
to HGC to the extent that HGC relied upon tiiat informatton This report is expressly for the sole
and exclusive use of the party for whom this report was onginally prepared and the particular
purpose for which it was intended Reuse of this report, or any portton thereof, for other than its
intended purpose, or if modified, or if used by third parties, shaU be at the sole nsk of the user
Plan to Investigate pH Exceedances in Perched 23
Groundwater Monitonng Wells
H \718000\pHdecrease\aprl2revision\pH Plan Exceedances in Perched GWM Wells Final doc
Apnl13,2012
TABLES
TABLE 1
Listing of Groundwater Monitoring Wells Currently in Out-of-Compliance Status
and Groundwater Wells in Accelerated Monitoring
Wells in Out-of-Compliance ("OOC") Status for Field pH
Well
Quarter/Sampling Events of Initial Consecutive Field pH measurements outside of
the GWCLs
MW-3 Q2 2010-Q3 2010
MW-3A Q2 2010-Q3 2010
MW-12 Q4 2010-Q1 2011
MW-14 Ql 2010-Q2 2010
MW-23 Q4 2010 - Ql 2011
MW-24 Q4 2010-Ql 2011
MW-25 Q4 2010 - January 2011 Monthly Sample
MW-26 July 2010 Monthly Sample - August 2010 Monthly Sample
MW-28 Q2 2010-Q3 2010
MW-29 Q4 2010-Q2 2011 (semi-annual sampling frequency)
MW-32 Q2 2010-Q3 2010
Wells in Accelerated Monitoring for Field pH**
Well Quarter/Sampling Events of Initial Field pH measurements outside of the GWCLs
MW-18 Q2 2010, Q3 2011 - Accelerated to quarterly from semi-annual
MW-19 Q2 2010, Q3 2011 - Accelerated to quarterly from semi-annual
MW-27 Q3 2011 - Accelerated to quarterly from semi-annual
MW-30 June 2011 Monthly Sample - Accelerated to monthly from quarterly
MW-31 June 2011 Monthly Sample - Accelerated to monthly from quarterly
All wells in OOC status are sampled at an accelerated frequency as required by the
Groundwater Discharge Permit UGW370004, Part IG 1
• The field pH measurements were outside on the GWCL on the dates listed above,
however, the measurements were not outside of the GWCL in consecutive sampling
periods Therefore, these wells are not in out-of-compliance status
H \718000\pHdecrease\aprl2revision\Table 1 - pH plan-wellstatus docx
TABLE 2
Tabulated pH Results from
INTERA 2011 GWCL Evaluation*
Well Constituent GWQS N % Detected Distribution (r2) Regression
Trend Z-Score
Mann-
Kendall
Trend
Mean
Standard
Deviation
(o)
Lowest
observed
pH value
Highest
observed
pH value
Poisson
Limit
(95%)
Original
Permit
GWCL
Comments
MW-1 pH 6 5-8 5 21 100 Normal or Log-Normal 016 downward 7 27 0 28 6 82 7 86 6 5-8 5 Flow Sheet Method
MW 2 pH 6585 14 100 Normal or Log-Normal 0 05 downward 7 02 0 26 6 44 748 6 5-8 5 Lowest Observed-Flow Sheet
MW 3 pH 6585 24 100 Normal or Log-Normal 034 downward 6 46 025 595 6 99 6 5-8 5 Lowest Observed Flow Sheet
MW-3A pH 6 5-8 5 22 100 Normal or Log Normal 0 42 downward 6 53 0 38 5 90 7 62 6 5-8 5 Flow Sheet Method
MW-5 pH 6 5-8 5 20 100 Normal or Log Normal 0 37 downward 744 016 715 7 67 6 5-8 5 Flow Sheet Method
MW-11 pH 6585 41 100 Normal or Log Normal 013 downward 7 73 0 28 7 22 8 40 6 5-8 5 Flow Sheet Method
MW-12 pH 6 5-8 5 22 100 Non-Parametric 0 14 -2 85 downward 6 70 0 27 5 86 715 11 36 6 5-8 5 Lowest Observed Flow Sheet
MW-14 pH 6 5-8 5 48 100 Normal or Log Normal 014 downward 6 58 0 20 615 719 6 5-8 5 Lowest Observed-Flow Sheet
MW 15 pH 65 85 19 100 Non-Parametric 0 08 -1 72 downward 6 79 0 18 6 24 7 01 11 54 6 5-8 5 Lowest Observed Flow Sheet
MW 17 pH 65 85 22 100 Normal or Log-Normal 0 08 downward 6 79 0 30 6 03 743 6585 Lowest Observed-Flow Sheet
MW-18 pH 6 5-8 5 26 100 Normal or lj)g-Normal 017 downward 6 59 0 37 5 82 7 23 6 5-8 5 Lowest Observed-Flow Sheet
MW-19 pH 6585 24 100 Normal or Log-Normal 0 26 downward 6 98 0 31 6 09 7 45 6 5-8 5 Lowest Observed-Flow Sheet
MW-20 pH 6 5-8 5 14 100 Normal or Log Normal 0 25 downward 716 012 6 95 7 42 6 5-8 5 Flow Sheet Method
MW-22 pH 6 5-8 5 13 100 Normal or Log Normal 0 37 downward 5 76 0 20 5 53 6 22 6 5-8 5 Lowest Observed-Flow Sheet
MW-23 pH 6 5-8 5 26 100 Normal or Log-Normal 0 25 downward 6 59 0 33 5 74 719 6 5-8 5 Lowest Observed Flow Sheet
MW 24 pH 6585 23 100 Normal or Log-Normal 0 34 downward 6 56 0 50 5 73 7 54 6585 Flow Sheet Method
MW 25 pH 6 5-8 5 28 100 Normal or log Normal 006 downward 6 71 0 21 6 36 7 25 6 5-8 5 Flow Sheet Method
MW-26 pH 6 5-8 5 31 100 Non-Parametnc 018 1 90 downward 6 70 040 6 06 7 88 11 24 6 5-8 5 Flow Sheet Method
MW 27 pH 6 5-8 5 27 100 Normal or Log Normal 0 04 downward 7 06 0 30 6 40 7 68 65 85 Lowest Observed-Flow Sheet
MW-28 pH 6 5-8 5 26 100 Normal or Log-Normal 0 36 downward 6 01 023 5 39 6 34 6 5-8 5 Lowest Observed-Flow Sheet
MW-29 pH 6 5-8 5 22 100 Normal or Log Normal 0 09 downward 6 45 0 27 5 78 6 92 6585 Lowest Observed-Flow Sheet
MW 30 pH 6585 33 100 Normal or Log-Normal 017 downward 6 90 0 21 6 53 7 47 6 5-8 5 Flow Sheet Method
MW 31 pH 65 85 34 100 Normal or Log-Normal 0 04 downward 7 18 022 6 65 7 80 6 5-8 5 Lowest Observed-Flow Sheet
MW 32 pH 65 85 44 100 Normal or Log Normal 0 25 downward 6 43 0 25 5 82 7 02 6 5-8 5 Lowest Observed-Flow Sheet
Notes
Proposed Frequency ot Re Evaluation is based on frequency of sampling for each well at the time of this report and EPA guidance (EPA 2009) suggesting re-evaluation of tiackground after eight additional data points
' Note This Table reflects pH data through the 1st Quarter of 2011 Denison is not proposing these GWCLs at this time This Table is provided for historic information purposes only
Revised Groundwater Compliance
Limits for pH in Monitonng Wells
White Mesa Mill Site Blanding Utah
H \718000\pHdecrease\apr12revision\pH_Table_histonc pH stats xls Table 2 GWCL
TABLE 3
Tabulation of Presence of
Pyrite, Iron Oxide, and Carbonaceous Fragments in Drill Logs
Well Pyrite 0 Fragments Iron Oxide
MW-3A X
^MW-16 X
^MW-17 X
^MW-18 X
^MW-19 X
^MW-20 X
^MW-21 X X
^MW-22 X
MW-23 X
MW-24 X
MW-25 X X
MW-26 X X
MW-27 X X
MW-28 X
MW-29 X
MW-30 X X
MW-31 X X
MW-32 X X
MW-33 X
MW-34 X X X
MW-35 X X X
MW-36 X X
MW-37 X X
Piez-2 X
Piez-4 X X
Piez-5 X X
DR-2 X X
DR-5 X X
DR-6 X X
DR-7 X
DR-8 X
DR-9 X X
DR-10 X
DR-11 X X
DR-12 X X
DR-13 X
DR-14 X X
DR-15 X X
DR-16 X X
DR-17
DR-18 X X
DR-19 X
DR-20 X X
DR-21 X
DR-22
DR-23 X X
DR-24 X X
DR-25 X X
H \718000\pHclecrease\apr12revision\
PyriteTable_rev0412 xls Table 3 Page 1 of 2 4/12/2012
TABLE 3
Tabulation of Presence of
Pyrite, Iron Oxide, and Carbonaceous Fragments in Drill Logs
Well Pyrite C Fragments Iron Oxide
TW4-1 X
TW4-2 X X
TW4-3 X X X
TW4-4
TW4-5 X X
TW4-6 X X X
TW4-7 X X X
TW4-8 X
TW4-9 X X X
TW4-10 X X
TW4-11 X
TW4-12 X X X
TW4-13 X X X
TW4-14 X
TW4-15 X X
TW4-16 X X
TW4-17 X X
TW4-18 X X
TW4-19 X
TW4-20 X
TW4-21 X X
TW4-22 X
TW4-23 X X X
TW4-24 X
TW4-25 X X
TW4-26 X
TWN-1 X
TWN-2 X X
TWN-3 X X
TWN-4 X
TWN-5 X X
TWN-6 X X
TWN-7 X
TWN-8 X X
TWN-9 X
TWN-10 X
TWN-11 X X
TWN-12 X X
TWN-13 X X
TWN-14 X X
TWN-15 X X
TWN-16 X X
TWN-17 X
TWN-18 X X
TWN-19 X X
Notes
C Fragments = particles of carbonaceous material (plant remains, etc)
^ = only moderately detailed log available
H \718000\pHdecrease\apr12revision\
PyriteTable_rev0412 xls Table 3 Page 2 of 2 4/12/2012
TABLE 4
Samples to be Submitted for Visual Examination of Pyrite
Well Pyrite Noted Cuttings Core Depth Interval Screen Interval
MW-26 (TW4-15) X X 92 5 - 95 62 5- 122 5
MW-26 (TW4-15) X X 95 - 97 5 62 5- 122 5
MW-34 X X 67 5 - 70 69-109
MW-36 X X 87 5 - 90 79 9- 119 9
MW-36 X X 1125-115 79 9- 119 9
MW-37 X X 110-1125 80 2- 120 2
TW4-16 X X 95 - 97 5 82-142
TW4-22 X X 90 - 92 5 535- 1135
TW4-22 X X 102 5- 105 535- 1135
TWN-5 X X 110-1125 80-150
TWN-5 X X 1125-115 80-150
TWN-8 X X 1175-120 75 5- 145 5
TWN-16 X X 87 5 - 90 43-93
TWN-19 X X 82 5 - 85 26-106
DR-9 X X 105- 107 5 82 1 -112 1
DR-12 X X 87 5 - 90 73-93
DR-16 X X 97 5- 100 NA
DR -25 X X 75 - 77 5 NA
Note
NA = not applicable (boring not completed as a well)
H \718000\pHclecrease\apr12revision\PyriteTable_rev0412 xls Table 4 4/12/2012
TABLE 5
Samples to be Submitted for Laboratory Analysis of Pyrite
Well Pyrite Noted Cuttings Core Depth Interval Screen Interval
MW-3A TBD^ TBD^ TBD' 78-95
MW-23 TBD^ TBD^ TBD' 109-129
MW-24 TBD^ TBD' TBD' 100-120
MW-25 X X 65 - 67 5 65-115
MW-26 (TW4-15) X X 90 - 92 5 62 5- 122 5
MW-27 X X 80 - 82 5 41 -91
MW-28 TBD^ TBD' TBD' 66-106
MW-29 X TBD' 95-125
MW-30 X X 65 - 67 5 67-107
MW-31 X X 95 - 97 5 69-129
MW-32 (TW4-17) X X 105- 107 5 80-130
Note
TBD' =tobe determined based on field screening
H \718000\pHdecrease\apr12revision\PynteTable_rev0412 xls Table 5 4/12/2012
FIGURES
l{ ' <>t>t'fu
tum
DR 10 (».V DI?>I2 Oft U
OR-U Off
V
4dL_.
EXPLANATION
# perctied monitoring viell
PIE21
a perched piezometer
DR 5
>1 perched piezometer instelled
* May/June 2011
X abandoned perched v«ll or bonng
'V.
1 mile •I
HYDRO
GEO
CHEM, INC
WHITE MESA SITE PLAN
SHOWING LOCATIONS OF PERCHED WELLS,
PIEZOMETERS, AND BORINGS
KEIEKEICE
H ff18000/pHdeaease/AJTMv«lloc srf
0
I V
.«"» 1 Tt »
;? I.,
• *
• ' >
DR10 OMi 0^2 01^8
1
DM9
WM5 OSJS
i
DIMS OIM» f
EXPLANATION
^ location of sample for ^ visual ven ticati on of pynte
4 perched monitonng well
PIEZ1
a perched piezometer
DR S
Ii pen*ied piezometer Installed Mer//June 2011
X abandoned perched v«ll or bonng
1 •
f
1 mile
r ' n HYDRO
^-•-^ GEO
^^4::^ CHEM, INC.
WHITE MESA SITE PLAN
SHOWING LOCATIONS OF SAMPLES TO BE
VISUALLY VERIFIED FOR PYRITE
HEIEREtOE
H ;?18000/()Hdecrease^)UTMsamplvissrf