DRC-2012-001031 - 0901a068802a4b97

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DRC-:.12-;01031
Denison Mines (USA) Corp.
105017th Street, Suite 950
Denver, CO 80265
USA
Tel: [phone]
Fax: [phone]S
www.denlsonmines.com
DENISO
MINES
201^ .
January 24, 2Qr\
VIA E-MAIL AND FEDEX
Rusty Lundberg, Executive Secretary
Utah Radiation Control Board
Utah Department of Environmental Quality
195 North 1950 West
P.O. Box 144810
Salt Lake City, UT 84114-4810
Re: White Mesa Mill Evaluation of Deep Supply Well WW-2
Utah Groundwater Discharge Permit No. UGW370004
Dear Mr. Lundberg:
Denison Mines (USA) Corp. ("Denison") has provided this letter and the enclosed report by Denison's
consultant, Hydro Geo Chem, Inc., in response to Part I.H.3. of the Mill's Utah Groundwater Discharge
permit No. UGW370004 (the "GWDP" or the "Permit").
Background
The Grimshaw Drilling, Inc. Well Driller's report for WW-2, dated March 1, 1980, indicated that WW-2 was
constructed with a 10 inch steel casing from 0 feet to 1,250 feet below ground surface ("bgs"), with a
cement grout seal from 0 to 100 feet bgs, and gravel pack from 100 to 1,250 feet bgs.
In a Request for Additional Information Related to Site Hydrogeology, Dated February 7, 2000, (the "RAI")
the Division of Radiation Control ("DRC") expressed a concern that the permeable annular gravel pack
from the bottom of the 10 inch steel casing, at 100 feet bgs, to the bottom of the well, at 1,250 feet bgs,
could provide a pathway for fluids from the perched zone to enter the casing of WW-2. DRC's rationale
for this concern was as follows: In the same RAI, DRC indicated that they had applied information from
MW-18, (located over 1,000 feet to the north-northwest of WW-2) in an attempt to estimate the depth of
the Brushy Basin contact at WW-2. The logged depth of the Brushy Basin contact at MW-18 was
recorded in the Peel Environmental Services well completion diagram as approximately 139 feet bgs.
Comparing the depth of the Brushy Basin contact from the remotely located MW-18 to the depth of grout
seal reported in the Grimshaw Well Driller's Report for WW-2, DRC apparently concluded that the 100
foot depth grout seal may not be keyed into the Brushy Basin Member of the Burro Canyon Formation.
In extrapolating that the depth of the Brushy Basin contact at WW-2 was the same as measured at MW-
18, DRC concluded that there may be 39 feet in the shallow unconfined aquifer open to the annual gravel
pack of WW-2, and that since the deep aquifer which provides the source of supply to WW-2, is lower
than the shallow perched zone, shallow groundwater could flow downward into the deep system. As a
result, as stated in the RAI, DRC concluded that hydraulic communication may exist in the annular space
of supply well WW-2. The RAI stated that DRC concluded the potential for pollution of the deep aquifer
would be small, except at abandonment, when the well would cease to be pumped. The RAI
Y:\WW2 lith investigation\Lr to Exec Sec WW2 investigation 1.23.12.doc
Letter to Mr. Rusty Lundberg
January 24, 2012
Page 2
recommended that a condition be added to the GWDP requiring that a plan for special measures for
plugging and abandoning be developed for WW-2.
In subsequent discussions between DRC and Denison, DRC requested that, based on the assumption
that the seal of WW-2 may not be keyed into the Brushy Basin Member, Denison accept a condition in the
GWDP requiring that Denison conduct an investigation to determine the integrity of the casing seal. The
assumption that the seal may not be keyed into the Brushy Basin Member, and the resulting requirement
to confirm the seal integrity, were based on the inaccurate extrapolation of the depth to the Brushy Basin
Member in MW-18, the only information available at the time of the revision of the GWDP.
Permit Condition
Specifically, the July 14, 2011 version of the Permit described the requirement for evaluation of the well
casing as follows:
"Plan for Evaluation of Deep Supply Well WW-2 - the purpose of this plan is to evaluate
the annular casing seal in water supply well WW-2, and to ensure adequate well casing
and annular seals, in compliance with the regulations of the Utah State Engineer (UAC
R655-4-9), with special emphasis on creating both a physical barrier and hydraulic
isolation between the shallow unconfined and the deep confined aquifers.
On or before January 31, 2012, the Permittee shall:
a) Conduct an investigation of water supply well WW-2 to verify that the casing and
annular seal is intact and creates both a physical barrier and hydraulic isolation between
the shallow unconfined and the deep confined aquifers, said investigation shall include
one or more of the following investigation techniques performed in accordance with
applicable guidance from the U.S. Environmental Protection Agency: well casing video
logs, cement bond logs, and/or temperature logs,
b) Show that the well casing and annular seal have physical and hydraulic integrity to
isolate the two aquifers mentioned above. In the event that hydraulic isolation of the two
aquifers is uncertain or unsubstantiated for any reason, the Permittee shall repair the well
casing and annular seal(s) to provide well construction that complies with the regulations
of the Utah State Engineer (UAC R655-4-9). After such repairs are completed, the
Permittee will conduct repeat testing using the investigation techniques required under
Part I.H.3(a) to demonstrate existence of the required hydraulic isolation, and
c) Submit a written report for Executive Secretary approval to document the investigation
and its findings, and any well repair activities. Said report shall be certified by a Utah
licensed Professional Engineer or Geologist."
Investigation
Denison evaluated the investigative options as provided in the Permit Part I.H.3, and determined that
most of the proposed options in this Part would be inconclusive in evaluating the physical and hydraulic
integrity of the seal from 100 to 139 feet bgs. Alternatively, with the recent addition of a number of newer
investigative wells in the proximity of WW-2 which demonstrated the likelihood that the Brushy Basin
contact near WW-2 may be significantly different that identified at MW-18, it was determined that there
was merit to re-evaluating and confirming the actual depth of the Brushy Basin Contact ih the vicinity of
WW-2.
Specifically, Denison's contract driller drilled and logged a boring at 50 feet southwest of WW-2 to
ascertain the conditions as near as practicable to WW-2. As discussed in the attached Hydro Geo Chem
DENISO MINES
Letter to Mr. Rusty Lundberg
January 24, 2012
Page 3
Report, drilling in the near vicinity of WW-2 in April 2011 has determined that based on the driller's log for
WW-2 and the lithologic log for nearby boring DR-1, the Brushy Basin Member/Burro Canyon Formation
contact at WW-2 is between 80 and 101 feet bgs, and the bore seal is likely keyed into the Brushy Basin
Member.
Conclusions
As discussed above, in the process of performing the requirements of Part I.H.3 of the Permit, Denison
has identified and confirmed that the information which formed the basis for DRC's requirement in this
section of the Permit was inaccurate. As a result of the investigation, Denison has confirmed that the
original grout seal in WW-2 was properly installed (keyed) and the well is adequately sealed to prevent
water from seeping into the lower aquifer. Based on the current information, Denison believes and
requests that Part I.H.3 a) through c) of the Permit are unnecessary, and should be deleted from the
Permit.
Please contact the undersigned if you have any questions or require any further information.
Yours very truly,
DENISON MINES (USA) CORP.
Jo Ann Tischler
Director, Compliance and Permitting
cc: David C. Frydenlund
Ron F. Hochstein
Harold R. Roberts
Jo Ann S. Tischler
David E. Turk
Stewart J. Smith, Hydro Geo Chem, Inc.
DENISO
MINES
HYDRO GEO CHEM, INC.
Envirottmental Science & Technolojjy
January 17, 2012
Ms. Jo Ann Tischler
Director, Compliance and Permitting
Denison Mines (USA) Corporation
1050 17th Street, Suite 950
Denver, Colorado 80265
Re: Results of a Lithologic Investigation at Deep Water Supply Well WW-2 Located at the
White Mesa Uranium Mill (The Site) Near Blanding, Utah
Dear Ms. Tischler,
This letter report provides the results of a lithologic investigation at deep water supply well WW-2
located at the White Mesa Uranium Mill (the site) near Blanding, Utah. WW-2 is completed within
the regional Navajo/Entrada aquifer more than 1,250 feet below ground surface (bgs). The purpose
ofthe investigation was to determine the depth of the contact between the Burro Canyon Formation
and the underlying Brushy Basin Member of the Morrison Formation which forms the base of a
relatively shallow perched water zone at the site.
The investigation was motivated by the Utah Department of Environmental Quality Division of
Radiation Control's (DRCs) concem that the WW-2 bore seal (extending to 100 feet bgs) was not
sufficiently deep to prevent shallow perched water from seeping into the gravel filled portion of the
annular space below the seal. DRC's concem was based on a logged depth to the Bmshy Basin
contact of approximately 139 feet bgs at MW-18, located approximately lOGO feet to the north-
northwest of WW-2 (Figure 1). Several borings installed in the vicinity of WW-2 since DRC
expressed its initial concern (including boring DR-1 as part of the present investigation) indicate that
the contact depth is variable and ranges from approximately 88 feet bgs to approximately 142 feet
bgs, and could be as shallow as 80 feet bgs based on the driller's log of WW-2.
Background
The first groundwater bearing zone beneath the site is relatively shallow perched water hosted
primarily by the Burro Canyon Formation. Where saturated thicknesses are greater, the perched
water rises into the overlying Dakota Sandstone. The Burro Canyon Formation is composed
primarily of sandstone and conglomeratic sandstone, with interbedded siltstone, claystone, and shale.
The Burro Canyon is underlain by the Brushy Basin Member of the Morrison Formation, a bentonitic
shale that essentially forms the base of the perched water zone. The Burro Canyon Formation is
separated from the underlying regional Navajo/Entrada aquifer by approximately 1,000 to 1,100 feet
C
51 West Wetmore, Suite 101 Tucson, Arizona 85705 1678 520.293.1500 520.293.1550-Fax [phone] toll Free
Ms. Jo Ann Tischler
January 17, 2012
Page 2
of Morrison Formation and Summerville Formation materials having a low average vertical
permeability. Water within the regional Navajo/Entrada aquifer is under artesian pressure and rises
approximately 800 feet above the top of the Navajo/Entrada aquifer in site water supply wells
completed within the Navajo/Entrada (TITAN, 1994)'.
The generally low permeability and typically small saturated thickness of the perched water zone
beneath the site make it unsuitable as a water supply for site operations. Most perched zone wells
installed at the site have yields that are less than about ¥2 gallons per minute. Water supply well
WW-2 was completed in Febmary, 1980 to provide a portion ofthe fresh water supply for the White
Mesa Uranium Mill in the early days of Mill operation. The annular space ofthe well was reported to
be grouted from the surface to 100 feet bgs. Below 100 ft bgs, the annular space was reported to be
gravel-packed. A copy of the well driller's report for WW-2 submitted to the State of Utah is
provided in Appendix A.
Installation and Logging of Boring DR-1
Boring DR-1 was installed approximately 50 feet southwest of water supply well WW-2 in April,
2011 as shown in Figure I. The purpose of the boring was to provide additional data to establish the
depth of the contact between the Burro Canyon Formation and the underlying Bmshy Basin Member
of the Morrison Formation.
Drilling and logging procedures were similar to those used previously at the site for the drilling of
perched zone monitoring wells (Hydro Geo Chem, Inc. [HGC], 2005)^ except that a smaller diameter
tricone bit (4 ¥4 rather than 6 %) was used. The 4 % inch diameter bit was sufficient because the
boring was installed only for lithologic logging purposes. Similar to other borings at the site, the
drilling technique was air rotary and drill cuttings were logged at 2 V2 foot depth intervals. Samples
of cuttings were bagged in labeled, zip-seal plastic bags and subsamples stored in labeled plastic
cuttings storage boxes. The boring was drilled into the Bmshy Basin Member of the Morrison
Formation and abandoned the day after installation.
The lithologic log for DR-l is provided in Appendix B. As shown, the depth of the Bmshy Basin
contact was logged at 101 feet bgs.
Results
Figure 2 shows the depths of the Bmshy Basin contact at boring DR-1 and perched monitoring wells
at the site. The contact depth in the vicinity of WW-2 is variable. The well driller's log for WW-2
(Appendix A) shows "Mud Stone - Blue Gray" between 80 and 150 ft bgs, suggesting that the
contact could be as shallow as 80 ft bgs. Contact depths are 92 feet at TWN-3 (to the southwest), 142
feet at TWN-18 (to the west-northwest), and 143 feet at TWN-8 (to the north). WW-2 appears to be
on a ridge-like feature in the Bmshy Basin upper surface that extends from WW-2 southwest to
TWN-3, TWN-2, and MW-27. The latter three wells have relatively shallow contact depths of 92,
' TITAN. 1994. Hydrogeological Evaluation of White Mesa Uranium Mill. Submitted to Energy Fuels Nuclear.
2
HGC. 2005. Perched Monitoring Well Installation and Testing at the White Mesa Uranium Mill, April through
June 2005. Submitted to Intemationai Uranium (USA) Corporation, Denver, Colorado.
H:\718000\WW2\WW2_investigation_ltr_ver2.doc
Ms. Jo Ann Tischler
January 17, 2012
Page 3
92, and 88 feet, respectively. The extent of this ridge-like feature near WW-2 inferred from the
depths to the Bmshy Basin is also shown in Figure 2.
Discussion
The contact depth at WW-2 is estimated to be between 80 and 101 feet bgs based on the drillers log
and boring DR-1. This indicates that the 100 foot depth of the grout seal in the annular space of
WW-2 is likely keyed into the Bmshy Basin Member. The likelihood that the gravel filled portion of
the annular space could serve as a conduit for perched water is considered negligible.
Even if some leakage of perched water were to occur in the gravel-filled portion of the annular space,
the perched water could not impact the regional Navajo/Entrada aquifer because of the
approximately 800 feet of artesian pressure measured in that aquifer beneath the site. Furthermore,
WW-2 is located upgradient of Mill operations and is substantially upgradient of the tailings cells at
the site as shown in Figure 3. WW-2 is upgradient of perched nitrate and chloroform plumes
identified at the site which precludes any potential impact to WW-2 from identified contaminants.
Conclusions
Based on the results of the investigation, the depth of the Bmshy Basin Member/Burro Canyon
Formation contact at WW-2 is between 80 and 101 feet bgs and the bore seal is likely keyed into the
Bmshy Basin Member. The 80 foot contact depth is based on the driller's log for WW-2 and the 101
foot depth is based on the lithologic log for nearby investigation boring DR-1.
Contact depths near WW-2 are variable and range from approximately 88 to 143 feet bgs at nearby
perched zone borings (Figure 2).WW-2 appears to be located on a ridge-like feature in the upper
Bmshy Basin surface as shown in Figure 2.
WW-2 is located upgradient of Mill operations, is substantially upgradient of the site tailings cells
and is upgradient of perched chloroform and nitrate plumes identified at the site (Figure 3).
Furthermore, the 1,200 foot deep Navajo/Entrada aquifer beneath the site is under approximately 800
feet of artesian pressure. The potential for seepage of any perched zone water or contaminants into
the gravel-filled portion of the annular space at WW-2 is considered negligible, and the water quality
of the Navajo/Entrada aquifer would be protected from any seepage that might potentially occur by
the artesian pressure in that aquifer.
Please feel free to contact me if you have any questions.
Sincerely,
Stewart J. Smith
Vice President
Attachments: Figures 1-3
Appendices A-B
H;\718(X)0\WW2\ WW2_mvestigation_lli_ver2.doc
TABLE OF CONTENTS
FIGURES
1 Locations of Perched Wells Supply Well WW-2 and Boring DR-1, White Mesa Site
2 Depths to Bmshy Basin, White Mesa Site
3 Locations of Perched Wells Supply Well WW-2 and Boring DR-1 Showing
3^^* Quarter, 2011 Water Levels and Chloroform and Nitrate Plumes
APPENDICES
A WW-2 Well Driller's Report
B DR-1 Lithologic Log
PROPERTY
BOUNDARY
MW-20
TW4-19
o
PiEZ-1
e '
SCALE IN FEET
EXPLANATION
perched monitoring well
temporary perched monitoring well
perched piezometer
TWN-1 temporary perched nitrate
Q3, 2011 chloroform
plume boundary
Q3, 2011 nitrate
plume boundary Q3, 2011 water level contour (ft amsl)
MW-36
WW-2
<>
DR-1 A
monitoring well
perched monitoring well
installed April, 2011
deep water supply well WW-2
boring installed April, 2011
HYDRO
GEO
GHEM, ING.
LOCATIONS OF PERCHED WELLS
SUPPLY WELL WW-2 AND BORING DR-1
SHOWING 3rd QUARTER, 2011 WATER LEVELS,
AND CHLOROFORM AND NITRATE PLUMES
APPROVED
SJS
REFERENCE
H:/718000/WW2/WW2Q3wl.srf
APPENDIX A
WW-2 WELL DRILLER'S REPORT
i: ' »
4Kottf«jz n. c ^ . T. D
k*t*<tteii £b*«i . .....
Water Well #2
REPOUT OF V/ELL pUILLEU
ST ATK OF UTAH • •'• . • :•*../•••. ••• Caor4ln»U .Ko.
lENEUAL STATKMKNT: Ueporl of well drmcr Is hereby made And /j|«!<l willi'lhe SUlc EnHneer; In^VccoVaahco with the Uwn of .Uuh.
ThU report shnll be i'lUd wiin tho SLat« Knglncer within 30 days alter the coin|>letion or abandonment, of tha wcU. Falluro to lib auch
cporta conatituloa a misdemeanor.) •.;,.. ••!: •.•.. • " V.v? •• •'*:"••• r 'Vii.'v^^^
l)J?ELL"0\VNEll: i . j
''*i»vV,?.Vv' ',,.'•1 -ir'r
2y:.0CAT^0N OP >YI2LL:
MKly^^A^i^-^-^^^ Ground WkUr Uaalo
SE
Section. .L
li word* nol ii««il«d) ' '"
V Mx*v* bUnkI
_.J»«t fram.—l^£ui»..Coiv«r Artr;laA ilow..,^...:..,;,........;... • ' " '
Temprrktura o( wotorJu...^
IMI diftwdpvfii »fur....N.ii._M.. .Mboon
K.p.ni.' .D*U .....m^^,^^
..ViU WM ft ckoaikU^BaJjrftU uadol No Yes •
8 (•trU«
3) NATURE OF WORK (check): ^.^ w.ii a
ephccfn«nt Well Q D«cpeninff Q Repair • '' AbaadoQ •
abaiidonfntnl. daerlbo mkUrUl and proeodunt
XI3)-WELLL0G:.:;^PW-H^^ -^^^
D«plti drilled«•..li»!1.885«..'«Ml»~(a«t. Depth al caiDp1«l«d w
NOTSi rUc« In th»'»pBC« or eeinbln»tlo».er •SBIBM BMHIWI to dal«;n»l^ lb* maUrUJ or cofitlilii*t|i»fi..o( molcrUlf «iieauiitcrcd In «*«h dtpth (nicrroL Undwr REMARIC3 at«kt anr deiiroUU neict to occvrrvnco ol watar and tK« color* paiuro, «tc.« of naUrUl on*
counltrcd In «aoh dtpth Initrval. UM addltloaat ibcci If ^«d«d.
4) NATURE OF USE (check):
BOBMtle •
I*. •.
TtgaUon a Mlt»lag Q Oth«r Q
BOBMtle • InduaUrUl |^ lAiinlelpal Q Stockwatar Q
5) TYPE OF CONSTRUCUON (check):
b)'CASIN6 SCHEDULE: Thraad«i o wdd«d a
DUm. Ireia Q loai to..lESfLjoot Cago , ?5Q I ^gQ
^ I.- • —•
" ** Olam. from ,, f>ct *•« ^ Cav*..
T M, ,„ «,.** Diam. from t *«- - - , „- • „ f«^t Gaea.
•w (2{ Bdcct a UMd a
7) PERFORATIONS:
rpc of perforator niod
M of pcrforaVlena
;^^..»_:.per/orKUon« fraai._.
I .perforation* from., ,
., ..—parforation* fram.
.perforatloB* fresa
.porforationa from
B]) SCREENS: Wdl ln»Ull«dT Y«a
nuBlaelnnr'a _
.Slot BIM^ ........Set (rom ...fU to..,
ain...^.„,»^.M...81ui AIXO... .....S«l from
ll CONSTRUCTION:
at wcll.sr»vcl p«ck«d1 Yea CX O BUa ot
*a««) p}»c«d (rom........ (•«1 to.... J.2.5.Q
a* a lurfao ac*! provided T Y«i ^
frXo what dcpliil.. 1.QQ. (•rt
fcl«rlaJ va«d to »aal
d anr at/Ata contain., unuaabla wat«r7 YiM
Vt o( water;
• No Q
„ .... DrpVb «C •traLa«_.«...«
ithod of a^allnc At«»t* o(( t —• , ...i...
ka furfivia cailr.C u»«J * Yra Q • No
a« It ctm«M<Ml In pUcc! Yet Q No a
10) WATER LEVELS:
tllc l«v«| . /t50 '««^ Uioi* land turfac* Data.
t«*Un ptrvaurff „..trH aLa«* Und turfaca D*u.
DC UECKIVKIJ: (11) FLOWLNG WELL:
Cttfiir«ll*d bf (cbavk) Valva Q
Cap .Q ' riut • No Cwolrol Q
1}M« UaW around c'aalax I Ya* Q
No Q
Wo.k .un«» .OC.t..!...l 0. i»..79 Complatad „• Fph, 18, .. 1 »SCL
(li) PUMP:
Mantifacturci't N»m*.—-
I>r;»th to pump or lH»*lm.« ...«~... (•«»
n. p.
Woll Drillcr'a Statement:
This well wea drilled under iny supervision, and this report b true to
ihc beat of my knowledge and belief.
r«Ame
4S22 No. 600 Cedar CUy, Utah b^\icO ^
(Sipped)
Licence No.^ZAD Date...„r.arrh 1
USE oTiiCu tivt rou ADDITIOKAU nruAiiua
APPENDIX B
DR-1 LITHOLOGIC LOG
Date 23 Geologist. ^, (SA^r/^'?<r Drilling Co. 2mc£^.M£(mniOjScL.
Pro perty ^J^/T^:MUL Project ^ Unit No Sec
County , State ,j^i!22£^ LocaMon
Hole Nn"bgl
- Twp. Rge,
(PYHlTEi PAGE J. OF ^
T.D. PPO Be
T.D. DRILL XZ'^.a
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