DRC-2012-001071 - 0901a068802a77bb

State of Utah
GARYR HERBERT
Governor
GREG BELL
Lieutenant Governor
DRC- 20 12-00 107 1
Department of
Environmental Quality
Amanda Smith
Executive Director
DIVISION OF RADIATION CONTROL
Rusty Lundberg
Director
January 19 2012
CERTIFIED MAIL
(Return Receipt Requested)
David C Frydenlund Vice President Regulatory Affairs and Counsel
Denison Mines (USA) Corp
1050 17* Street Suite 950
Denver CO 80265
Subject Nitrate Corrective AcUon Plan for the White Mesa Mill Site dated November 30 2011
(Under Cover Letter Dated November 29 2011) DRC Review Comments
Dear Mr Frydenlund
The Division of Radiation Control (DRC) review comments regarding the November 30 2011 Denison
Mines (USA) Corporation (DUSA) Nitrate Corrective Action Plan for the White Mesa Mill Site are
enclosed (via URS Memorandum)
Please review the comments as soon as possible DRC anticipates that DUSA should be able to respond to
the comments and submit a revised CAP on or before Monday Febmary 27 2012 If DUSA does not
agree with this due date then please request an altemate date including justification(s) for the extension on
or before close of business January 24 2012
If you have questions or concems regarding the comments or would like to arrange a meeting or
teleconference to discuss the comments please contact Tom Rushing at [phone] Thank you
Sincerely
UTAH WATER QUALITY BOARD
Rusty Lundberg
Co Executive Secretary
Enclosure URS Memorandum (4 pp)
F \DUSA\Nitrate Corrective Action PlanM 1 28 11 CAP\DRC URS CommentsNNitrate CAP 11 30 11 DRC Comments Cover Ltr docx
195 North 1950 West Salt Uke City UT
Mailing Address PO Box 144850 Salt Uke City UT 84114 4850
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Certif ed Fee
RE""1/19/12 D|C REVEIW COMMENTS
David C Frydenlund
Vice President & General Counsel
Denison Mines (USA) Corp (DUSA)
1050 17th ST STE 950
Denver CO 80265
PS F»ri-n 3tM. August 2Me See Reverse (•r Instructions
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URS
MEMORANDUM
To Tom Rushing (DRC) Loren Morton (DRC) Phil Goble (DRC)
From Paul Bitter (URS) Jeremy Cox (URS) Rebecca Brown (URS) Jon Luellen (URS)
cc Robert Baird (URS)
Date 19 January 2012
Re Comments on the Corrective Action Plan for Nitrate White Mesa Uranium Mill Near
Blanding Utah dated November 30 2011
This memorandum contains the comments by URS and the Utah Department of Environmental
Quality Division of Radiation Control (DRC) on the Corrective Action Plan for Nitrate at the
White Mesa Mill Site The Corrective Action Plan was prepared for Denison Mines USA (DUSA)
by Hydro Geo Chem Inc and was dated November 30 2011 Comments have been provided by
URS as a deliverable for Contract No 116259 issued through the DRC This review also is in
accordance with the amended Memorandum of Understanding (MOU) between the DRC and
DUSA dated December 2011 For purposes of expediency the URS and DRC comments are
edited for conciseness and combined into one memo Note that format grammar and punctuation
in the Corrective Action Plan were not reviewed for accuracy and consistency
The comments regarding the Corrective Action Plan for Nitrate dated November 30 2011 are
presented below Please note that this document must meet the minimum requirements specified
in the September 30 2011 Stipulated Consent Agreement (SCA) Based on this review not all of
the minimum requirements of the SCA have been met by the Corrective AcUon Plan for Nitrate
dated November 30 2011 These shortcomings must be addressed to saUsfy the SCA
1 General comment regarding figures Several well symbols are presented on the figures that
do not convey addiUonal information to the reader Three different symbols are used for
monitonng wells based on when the wells were mstalled for example wells MW 33 MW
34 MW 35 MW 36 and MW 37 Because wells MW 35 MW36 and MW 37 are tailings
monitoring wells they should have the same symbol as the perched monitonng well
symbol Wells MW 33 and MW 34 are currently not required to be sampled therefore they
can have a separate symbol Furthermore the identification of wells currently used for
groundwater extraction at the site (relative to the chloroform plume) is important information
that though it is discussed in text and tables is not currently displayed on any of the figures
Please identify the current extraction wells with a unique symbol on the figures where
appropriate
2 General comment The document repeatedly uses the term permeability interchangeably with
hydraulic conductivity These parameters are not interchangeable Permeability is a function
of the geologic media alone whereas hydraulic conductivity takes into account the density
Page 1 of 8 URS
and viscosity of the fluid flowing through the geologic media Since values quoted in the
plan are in terms of centimeters/second which is the unit for hydraulic conductivity then all
references to permeability within the document should be replaced with hydraulic
conductivity
3 SecUon 1 Please add a statement within this section that all nitrate concentrations in
groundwater in this document are expressed as mg/L as nitrogen
4 Figures 1 3-7 9-10 12-13 Label the Cottonwood Canyon Corral Canyon and Ruin
Spnng on the figures since they are referenced in the report If these features are outside the
bounds of the figure then include another figure that references on a larger scale these
features with respect to the White Mesa Mill Site
5 Figure 8 The histoncal pond is not clearly labeled on Figure 8 It is assumed that the
historical pond is the irregularly shaped red figure in the area of TWN 2 but it should be
more clearly labeled
6 Section 1 Paragraph 4 The August 2011 document should be named Nitrate Investigation
Revised Phases 2 through 5 Work Plan (not Plau)
7 Figure 13 Please identify on this figure (1) the proposed extraction wells using the same
symbol as used on Figure 1 and (2) the current extraction wells in operation at the site
8 Section 2 2 p 6 In the third bullet m the first paragraph and the second sentence in the
second paragraph in this section a conclusion is presented that there are no unaddressed
current or ongoing sources of contamination However based on the discussion in the last
paragraph of Section 2 1 and other statements made in the 2nd and 3rd paragraphs of Section
2 2 Denison and the Executive Secretary have acknowledged that it has not been possible to
date to determine the source(s) cause(s) attribution magnitudes of contribution and
proportion(s) of the local nitrate and chloride m groundwater beneath the mill site Given the
remaining uncertainty associated with potential sources of the elevated nitrate and chlonde
concentrations in groundwater it is recommended that the cited conclusion be revised e g to
indicate that there are no known unaddressed current or ongoing sources of contamination
For similar reasons please delete the text at the beginning of the third paragraph through
That is
9 Section 2 2 Section 4 5 2 It is doubtful that nitrate plume stability can be assessed with only
two years of data considering the low hydraulic conductivity of the site It will likely take
several years to assess plume stability It is better to state that the plume has been stable
over the period of seven sampling quarters but long term plume stability has not been
established AltemaUvely please provide additional years of histoncal data to demonstrate
the stability of the plume
10 Section 3 2 2 pp II 12 SecUon 7 2 p 31 Section 8 7 p 42 DUSA states that Phase II will
include a passive strategy of relying on natural attenuation processes to reduce nitrate
concentrations DRC agrees that natural attenuation will occur at the site to some extent
however DUSA does not clarify whether the idenUfied natural attenuation mechanisms
(hydrodynamic dispersion and dilution by recharge) will occur to the degree needed to meet
remedial goals DUSA notes that downgradient portions of the plume will require reduction
Page 2 of 8 URS
m nitrate concentrations to meet the 10 mg/L target Please clanfy how these processes will
be substantiated (e g monitoring) Also please discuss the performance measures which
will be used to assess natural attenuatton (e g decreasing trends for nitrate/nitnte at
monitoring wells) and projected Umeframes to meet the 10 mg/L target
11 Section 43 p 17 par 2 and Figures A 1 thru A4 The cross sections provided do not
provide mformation on the extent and range of concentrations of nitrate (nitrate + nitrite as N)
present in groundwater that exceed 10 mg/L in Well MW 30 and in the perched zone in the
area between Well MW 30 and MW 31 For example the concentration of nitrate (nitrate +
nitrite as N) shown for Wells MW 30 and MW 31 on Figure A 1 are 16 mg/L and 21 mg/L
respectively but the 10 mg/L contour on this figure wraps Ughtly around the wells
Additionally the interpretive cross section depicted on Figure A 2 indicates that the
downgradient (southwestward) lateral extent of nitrate concentrations in groundwater
exceeding 10 mg/L extends somewhat beyond the location of Well MW 31 The well bore
depicted for Well MW 31 in this cross section also indicates that that wellbore intercepted
two conglomeratic zones in the perched water zone portion of the Buno Canyon FormaUon
InvestigaUons at other locations at the White Mesa Mill Site (e g vicinity of Wells MW 4
and TWN 16) have shown that these zones can be more permeable than non conglomeratic
zones in this formation and can thus facilitate groundwater plume migration No wellbore
lithologic log information is provided for Well MW 30 Please provide additional
information on specific strata intercepted in wellbore MW 30 and addiUonal informatton on
the potential extent of conglomeratic zones in the perched water zone in the area between
Well MW 30 and MW 3 Also provide additional information to assess whether the zones
of capture from proposed pumping of groundwater from Wells TW4 24 and TW4 22 would
be sufficiently large to capture the zone of existing impacted groundwater between Wells
MW 30 and MW 31 and downgradient of these wells
12 Section 4 3 2 third paragraph Figure 4 shows the groundwater mounding around the
wildlife ponds that is mentioned in the text Figure 4 also shows a disttnct groundwater
mound around well TWN 2 The groundwater mound beneath TWN 2 appears to be
unrelated to the recharge from the wildlife ponds because the groundwater elevatton in
TWN 4 which lies between the wildlife ponds and TWN 2 is less than the groundwater
elevation at either TWN 2 or the wildlife ponds Please explain the apparent groundwater
mounding in the area of TWN 2 m this paragraph Also in later secttons explain the cause
and effects of the apparent groundwater mound at TWN 2 on the planned groundwater
extraction
13 Section 4 5 1 p 23 In the 2nd and 3rd paragraphs on this page a conclusion is presented
that there are no unaddressed current or ongoing sources of contamination Similar to
Comment No 8 above it is recommended that the cited conclusion be revised eg to
indicate that there are no known unaddressed current or ongoing sources of contamination
14 Sectton 4 5 2 second paragraph last sentence Please remove the statement regarding the
absence of significant continuing sources of nitrate to the perched water This claim is
unsubstantiated
Page 3 of 8 URS
15 Section 5 1 A more ngorous discussion of the histoncal pond would be helpful especially
since the aquifer beneath the pond has the highest nitrate concentrattons A discussion on the
origin and use of the pond would be key to understanding a potential source of the nitrate
impacts around TWN 2
16 Figure 11 1 Add labels for the Mill process building the V205 Mini Lab and Precipitation
Area and Mill s Pulp Storage Tanks to the figure
17 Section 6 third sentence Please rephrase so that the sentence indicates that once the nitrate
concentrations in all monitonng wells are 10 mg/L or less
18 Sectton 7 fifth paragraph last sentence This sentence currently states that the
implementation of Phase III will be based on assessments conducted during Phase III Please
clarify this statement
19 Section 7 1 Step 1 Denison proposes to construct a sloped curbed and drained concrete
pad of six inches in depth over an area covering at least twice the extent of contamination
identtfied dunng the contamination investigation In Figure 11 2(b) the planned concrete
pad appears to extend approximately 37 feet to the east of the existing concrete pad
underneath the ammonium sulfate storage tanks it is not clear exactly where the locations of
the two 2011 soil borings would be located underneath the cap This approach does not
comply with the requirements of the SCA dated September 30 2011 Though the
construction of a concrete pad is required by the SCA the SCA also requires that during
Phase I DUSA must determine to the satisfaction of the Executive Secretary the physical
extent of the soil contamination observed at the Ammonium Sulfate Crystal Tanks near
bonngs GP 258 and GP 26B including both an estimate of surface area of the contammated
soil and an estimate of the volume of contaminated soil down to but not including bedrock
Two sampling locations are insufficient to determine the lateral extent of contamination and
the depth to bedrock is not clearly stated in this sectton The CAP must be revised to include
(1) a statement regarding the depth to bedrock in the area of the ammonium sulfate crystal
tanks and (2) a plan to delineate at least approximately the lateral extent of elevated
concentrations of ammonium and nitrate m the soil The volume of contaminated soil cannot
be estimated unttl these data are available and therefore the pad construction should be
deferred until the extent of subsurface contamination is investigated DRC agrees that soil
bonngs are not practtcal m areas occupied by structures but additional soil bonngs must be
performed around those structures in accessible locations For the porttayal of the delineation
of the lateral extent of elevated ammonium and nitrate in soil around the Ammonium Sulfate
Crystal Tanks DRC suggests a screening level equivalent to twenty ttmes the background
95% upper confidence levels (UCLs) denved for ammonium and nitrate in soil during the
2011 investigations The screening levels would be 42 9 mg/kg for ammonia as N and 43 8
mg/kg for nitrate as N on a dry weight basis The proposed screening levels are less than
three percent of the maximum detected concentrations m GP 25B and GP 26B
20 Section 7 1 Step 1 The installatton of the concrete pad will minimize or prevent infiltratton
of water onginating from precipitation or surface spills These sources of water however
could be relatively minor compared to contnbutions from leaking pipes beneath or near the
P g 4 f8 URS
pad If such sources exist they will continue to transport nitrogen from the vadose zone to the
perched groundwater and adversely impact the effectiveness of the proposed groundwater
extraction program The apparent groundwater mound in the vicinity of TWN 2 as shown
on Figure 4 could be the result of leaking pipes DRC requests that DUSA include in the
CAP a figure showing all of the known or suspected subsurface piping m the vicinity of the
Ammonium Sulfate Crystal Tanks Furthermore DRC recommends the installation of water
meters (or leak detection devices) on the inlet and outlet of any piping beneath or near the
proposed concrete cap If the water meters or devices mdicate a potential leak the piping
should be decommissioned or repaired thus removmg the source of water and the subsequent
transport of the ammonium and/or nitrate to the perched groundwater
21 Section 7 1 Step 1 In either the revised CAP or within a revised Discharge Mimmizatton
Technology (DMT) Monitoring Plan DUSA must include a plan for periodic inspection and
photographic documentatton of the condition of the pad At a minimum the mspections
should occur annually and the mspection reports should mclude a record of any repairs that
are needed for the pad repairs must occur pnor to the subsequent mspection The inspectton
cntena should be similar to those for other facilities such as the New Decontaminatton Pad
If discrepancies are identified [i e crack m the concrete with greater than 1/8 inch separation
(width) or any significant detenoration or damage ofthe pad surface] repairs should be made
prior to resuming use ofthe Ammonium Sulfate Crystal Tanks The inspection findings any
repairs required and repairs completed should be included in the 2 ^ Quarter DMT
Monitoring Report due September 1 of each calendar year which is also required by
facilities that go through an annual inspection of concrete integnty
22 Section 7 2 second paragraph on Page 32 seventh sentence Please remove the statement
regarding the absence of significant continuing sources of nitrate to the perched water
This claim is unsubstantiated
23 Section 7 2 It is doubtful that TWN 2 will yield 400 feet of downgradient capture zone due
to the low transmissivity in the area This potentially leaves an area of impacted groundwater
between TWN 2 and TW4 24 that will not be captured by pumping An additional pumping
well between TWN 2 and TW4 24 is therefore needed
24 Section 7 2 Pumping tests can be conducted to help establish the capture zone DRC
recommends that an effort be made to model the anticipated capture zones of the nitrate
pumping wells especially in conjunctton with the chloroform pumping wells
25 Sectton 7 2 The plan states that hydraulic capture will be considered successful if the
concentrattons of nitrate m MW 30 and MW 31 remain stable or decline and if
concentrations of nitrate in downgradient wells MW 5 and MW 11 do not exceed the
10 mg/L standard Based on the present position ofthe plume the downgradient wells MW 5
and MW 11 presently do not exceed the 10 mg/L standard Therefore by the above
reasoning we could say that hydraulic capture is successful even without pumping Please
refine the cntena for MW 5 and MW 11 to state that hydraulic capture will be considered
successful if the nitrate concentrattons in these wells do not exceed their respecttve Ground
Water Compliance Limit (GWCL) of 2 5 mg/L
Page 5 of 8 URS
26 Section 7 2 The plan states that neither biologically mediated decomposition of nitrate nor
abiottc chemical decomposition are expected to be significant mechanisms m reducing nitrate
concentrations and that nitrate is not expected to be retarded by adsorption onto aquifer
solids Please provide specifics as to why these processes are not expected to occur at the
site
27 Section 7 2 1 Please include specifics of well abandonment procedures and applicable rules
and regulations in the plan The DRC agrees that is appropriate to abandon some nitrate
wells as they are not needed however please add to this section The wells ultimately
abandoned will require prior approval by the Executtve Secretary The DRC believes that
some wells should be left in place for historical head monitonng data Head monitoring data
are collected from these wells on a quarterly basis and is submitted in DUSA s Quarterly
Ground Water Monitonng Reports
28 Sections 7 2 4 8 1 and 10 2 3 Please provide additional informatton in these sections
regarding the current sampling frequency for nitrate (Nitrate + Nitrite as N) for monitoring
wells located downgradient of the leading edge (downgradient limit) of the current 10 mg/L
ISO concentration contour (e g Wells MW 05 and MW 11) to assess the possible need to
obtain and provide routine (e g quarterly) analytical data to confirm the spatial and temporal
stability of the nitrate plume s downgradient extent
29 Secttons 724 725 81 82 1023 andl026 Please provide additional informatton that
assesses the need for analyzing and providing (in quarterly reports) analytical data from
selected on site wells for other groundwater quality parameters that based on the results of
site investigations into possible contaminant source areas pubhshed results from other
facilittes (e g see Goenng et al 1992 Waugh et al 2010) and requirements contained m
the White Mesa Mill Groundwater Discharge Permit GWDP UGW370004 could likely or
potenttally be considered relevant to this CAP and the associated CAP monitonng and
reporting program including the following
• Ammonia (total ammonia = some of unionized ammonia [NH3 ] form + ionized
ammonium ion [NILj"^] form)
• pH
• DO
• Temperature and/or
• Other potenttally relevant data
Analysis and reporting of groundwater samples for ammonia/ammonium is consistent with
groundwater compliance cntena hsted in Table 2 of the Groundwater Discharge Permit
UGW370004 and with hkely or potential on site sources of contaminants that have been
identtfied for the nitrate plume (e g ammonium sulfate crystal tanks) If sufficient natural
attenuation is not observed m the concentrations of nittate m the selected monitonng wells
dunng Phase II additional analyses (e g stable isotope analyses) should be performed dunng
Phase III to better charactenze the attenuatton processes at the site
Page 6 of 8 URS
30 Section 72 4 p 35 and Section 102 6 p46 The discussion in these sections (Reporting)
for Phase II of the CAP indicates that certain information relattng to the detailed design and
constructton of the remediation system and informatton on maintenance procedures to be
used dunng remediation system operation would not be provided to the State DEQ for
review This informatton needs to be provided for review to comply with condittons listed m
Item 11 B 5 b ofthe SCA Examples of types of informatton that should be included m these
reports for review include but are not limited to the followmg
• Details regarding proposed groundwater tubing and piping conveyance systems (e g
for conveying exttacted groundwater from the pumping wells to the disposal cell)
• Informatton on /specification sheets for inline flow meter or flow totalizers to be
used
• Information on/specification sheets for groundwater pumps to be used and/or
• An Operation and Maintenance Manual (required m Phase II)
Please revise the text in these sections to include all necessary informatton for the quarterly
reports as required by the SCA
31 Section 7 24 p 35 and Section 10 2 6 p46 The discussion m these secttons (Reporting)
for Phase II of the CAP indicates that the quarterly reports would not include certain types of
important information that would allow State DEQ personnel to (independently) venfy
findings that will presented in the reports with regard to remediation system performance
This information should be provided for review and verification purposes and to comply with
condittons hsted in Item 11 B 5 c ofthe SCA Examples of types of information that should
be included in these reports for review include but are not limited to the following
• Tabular compilattons of groundwater level measured in non pumped wells through
time as recorded on a routine basis
• Water level data from pumped wells over time as recorded on a routtne basis
• Running and cumulative groundwater volumes removed from each pumping well as
recorded on a routine basis and
• Calculations and/or spreadsheets documenting calculated nitrate mass removal rates
Please revise the text in these sections to include all necessary information for the quarterly
reports as required by the SCA
32 Section 8 1 pp 39 40 and Sectton 8 2 p 40 Please specify all wells within the plume to be
used for the evaluation of concentration trends As a measure of pumping performance DRC
would expect that all effected well data will mdicate a decreasing trend for nitrate + nitrite
(as N) for all wells within the plume and if other results are shown then DUSA would
conform to an approved contingency plan Such contingency plan would include timely
evaluation of cntena to determine successful/unsuccessful pump performance and timeframes
(from recognition of unsuccessful performance) to evaluate the need for additional pumping
wells or an alternate remediation technology (Phase III) Please include such a contingency
plan with schedules in the CAP
Page 7 of 8 URS
33 Section 8 6 p 42 Determination of whether the CAP will have a permanent effect is
required to be based on appropnate long term groundwater monitoring and is dependent on
effectiveness of Phase 1 and II implementation as well as studies and evaluations for Phase III
(affirmattve and defensible demonstration) in conformance with Utah Administrative Code
R317 6 6 15(D and E) Please remove the second sentence As concentrations will then
continue to be reduced by natural attenuation the corrective action will have a permanent
effect and include language that demonstration that the action will produce a permanent
effect will be based on appropriate future evaluations
34 Figures 7 and 13 The area of the nitrate plume shown on these figures should be dashed
This is an approximate area of the nitrate plume
35 Figure 11 1 Please supply all results in the table as mg/kg on a dry weight basis instead of
the current units of mg/L for aqueous extract
[End of comments]
References cited in comments
Goenng TJ A Groffman andB Thomson 1992 Demtrification in Groundwater at Uranium
Mill Tailings Sites Waste Management Symposium 1992 4pp URL
http //www wiTtsvm oig/archi\es/1992/V]/122 pdf
Hyman M andRR Dupont 2001 Groundwater and Soil Remediatton Process Design and
Cost Esttmattng of Proven Technologies American Society of Civil Engineers Press Reston
VA 517 pp
Utah Water Quality Board 2011 Docket No UGW09 03 A Amended Stipulated Consent
Agreement in the Matter of Denison Mines (USA) Corp 1050 17''' Street Suite 950 Denver
Colorado 80265 30 September 2011
Waugh W J D E Miller S A Moms L R Sheader E P Glenn D Moore K C Canoll L
Benally andM Roanhorse 2010 Natural and Enhanced Attenuation of Soil and Groundwater
at the Monument Valley Arizona DOE Legacy Waste Site—10281 WM2010 Conference
March 7-10 2010 Phoenix AZ URL
http//ww^^ wmsvm org/app/2010cd/wi-n2010/pdfs/10281 pdf
Page 8 of 8 URS