DRC-2011-007477 - 0901a0688027c646

DENISO
MINES
Denison Mines (USA) Corp.
105017th Street, Suite 950
Denver, CO 80265
USA
Tel : [phone]
Fax:[phone]
www.denisonmines.com
October 3, 2011
VIA E-MAIL AND OVERNIGHT DELIVERY
Mr. Rusty Lundberg
Utah Department of Environmental Quality
195 North 1950 West
P.O. Box 144850
Salt Lake City, UT 84114-4850
Re: State of Utah Groundwater Discharge Permit ("GWDP") No. UGW370004
Notice of Violation and Groundwater Corrective Action Order, Docket No. UGW20-01. Denison
Mines ("USA") Corp. Submittal of a Plan and Work Schedule to Drill and Install Well TW4-27 -
Conditional Approval Letter.
Dear Mr. Lundberg:
Attached as Appendix A to this letter, is Denison's Plan of Action and Work Schedule (the "Plan"), Revision 1,
for the installation of chloroform monitoring well TW4-27. The Plan, Section 2(c), has been modified as
agreed to in correspondence between DRC and Denison, dated August 15, 2011, August 24, 2011 and email
communications dated August 31, 2011 and September 13, 2011.
Additionally, The Hydro Geo Chem Letter dated June 17, 2011, which recommended the approach for the
installation of TW4-27 is enclosed as Attachment 1 to this letter.
Please contact me if you have any questions or require any further information.
Yours very truly,
I)ENisoN MINES (USA) CORP.
^Jo Ann Tischler
Director, Compliance and Permitting
cc: David C. Frydenlund
Harold R. Roberts
David E. Turk
K. Weinel
Central files
Attachments
N.\Chloroform\New Cfm well SE\9.22.11 UDEQ letter and response\transltr for 10.3.11 Plan and Scfiedule.doc
DENISO
MINES
Denison Mines (USA) Corp.
105017th street. Suite 950
Denver, CO 80265
USA
Tel : [phone]
Fax: [phone]
www.denisonmines.com
APPENDIX A
WHITE MESA MILL
Notice of Violation and Groundwater Corrective Action Order, Docket No. UGM20-01
PLAN OF ACTION
And
WORK SCHEDULE
Revision 1
For the Installation of One or More Monitoring Wells Downgradient of
TW4-4 and TW4-6
Denison Mines (USA) Corp.
1050 1/^ Street, Suite 950
Denver, CO 80265
October 3, 2011
N:\Chloroform\New Cfm well SE\9.22.11 UDEQ letter and responseM 0.3.11 Rev 1 Plan for DEQ 9.22.11 letter.doc
Plan of Action and Work Schedule
Revision 1
October 3, 2011
Page 2
Reference is made to the letter from the State of Utah Division of Radiation Control ("DRC") dated May 26,
2011, requesting additional information relating to the chloroform groundwater investigation at the Denison
Mines (USA) Corp. ("Denison") White Mesa Mill (the "Mill"), pursuant to Notice of Violation and Groundwater
Corrective Action Order, Docket No. UGW20-01.
In accordance with the recommendations in Hydro Geo Chem Inc.'s letter report dated June 17, 2011 (the
"Hydro Geo Chem Report"), Denison proposes the following plan of action and work schedule the (Plan") to
complete the installation of one or more wells in locations hydraulically downgradient of existing chloroform
monitoring wells TW4-4 and TW4-6 to demonstrate that the chloroform plume is bounded and to assure that the
plume is under hydraulic capture in this vicinity:
1. Work Plan
1.1. Installation of TW4-27
A single new well (TW4-27) will be installed south of TW4-14 and east of TW4-6 and TW4-26 at the location
provided on Figure 6 of the Hydro Geo Chem Report. A single well at this location is considered adequate to
ensure that chloroform does not move undetected in an unanticipated easterly direction toward the eastern
property boundary. TW4-27 will be a monitoring well and will not be a pumping well.
The proposed location for TW4-27 would
a) extend the current network of easternmost monitoring wells to the south,
b) provide additional data to indicate whether the water level at TW4-14 is anomalous, and
c) provide additional data to address UDEQ's concerns about potential eastward migration of chloroform.
TW4-27 will be permanent and constructed in accordance with UAC R317-6-6.3(l)(6) and will comply with Part
1.F.6 of the Denison Ground Water Discharge Permit No. UGW370004. TW4-27 will be sampled quarterly for
the analytical parameters listed in section 4 in Appendix A of the White Mesa Uranium Mill Ground Water
Monitoring Quality Assurance Plan.
1.1.1. Aquifer Testing of TW4-27
Provided there is sufficient saturated thickness, Denison will perform a hydraulic test at TW4-27 to:
a) Calculate permeabilities and hydraulic conductivities; and
b) Calculate local groundwater velocities.
Such aquifer testing will be described in a report (the "Hydrogeologic Report") that will be submitted to the
Executive Secretary.
1.1.2. Reporting
DENISO
MINES
Plan of Action and Work Schedule
Revision 1
October 3, 2011
Page 3
Analytical results for chloroform samples from TW4-27 and water levels will be reported in the Quarterly
Chloroform Monitoring Reports that are filed with the Executive Secretary of the State of Utah Radiation Control
Board (the "Executive Secretary").
Denison will expand the chloroform capture zone and groundwater contour maps in those reports to include
sample results and groundwater head data at TW4-17.
1.2. Collection of Additional Water Level and Chloroform Data to Determine if TW4-27 Satisfies the
Stipulated Criteria
Water level and chloroform concentration data collected from the existing wells, and upon completion from
TW4-27, will be used to determine if:
a) the 70 pg/l chloroform isoconcentration line remains hydraulically upgradient of TW4-27; and
b) groundwater contour lines show that TW4-27 is hydraulically downgradient of TW4-4 and TW4-6.
1.3. Possible Abandonment of TW4-14
If water level data from TW4-27 indicate that the water level at TW4-14 is anomalous, TW4-14 will be
abandoned, with the approval of the Executive Secretary. The water level at TW4-14 will be considered
anomalous if the water level at TW4-27 is comparable to the water level at TW4-6.
1.4. Installation of Additional WelKs) if Necessarv
It may take some time for the hydraulic system to adjust to the addition of TW4-27. However, if after two
quarters of data, the criteria set out in paragraph 1.2 above are not satisfied, then Denison will propose a plan
and schedule at that time for the location of one or more additional wells, based on the information gained from
monitoring TW4-27.
2. Schedule
Denison proposes that the foregoing Plan be performed in accordance with the following schedule:
a) TW4-27 will be installed within 30 days after receipt of Executive Secretary approval of this Plan. An
as-built report, along with the Hydrogeologic Report, will be submitted to the Executive Secretary
within 60 days after the date of such approval.
b) Quarterly water level measurements and sampling will commence during the next regularly scheduled
chloroform sampling campaign after installation of the well. A determination of whether or not the
criteria specified in paragraph 1.2 above have been satisfied with the addition of TW4-27 will be made
after receipt of two quarters of water level and chloroform data. A decision whether or not to abandon
TW4-14 will also be made by Denison and the Executive Secretary at that time.
c) If the Executive Secretary determines, after review of the second Chloroform Monitoring Report that
contains the second of two quarters of data, or at any time that the criteria specified in paragraph 1.2
above have not been satisfied with the addition of TW4-27, then Denison will submit within 30 calendar
days of written notice from the Executive Secretary, a plan and schedule for installation of one or more
additional chloroform monitoring wells. The new well(s) must show that the 70 ng/L chloroform
DENISO
MINES
Plan of Action and Work Schedule
Revision 1
October 3, 2011
Page 4
isoconcentration line remains hydraulically up gradient to the new well(s) and the groundwater contour
lines must show the new well(s) are hydraulically down gradient to TW4-4 and TW4-6.
DENISO
MINES
Plan of Action and Work Schedule
Revision 1
October 3, 2011
Page 5
ATTACHMENT 1
DENISO
MINES
HYDRO GEO CHEM, INC.
Environmental Sctcncc &• Technology
June 17,2011
David Frydenlund, Esq.
Denison Mines (USA) Coip.
1050 17th Street, Suite 950
bcnver, Colorado 80265
Dear Mr< Frydenlund,
This letter provides a recommended approach in response to the Utah Pepartment of Envirorimentai
Quality's (UDl^Q's) concerns regard the southern tip of the perched zone chloroform piume at
P^mspn Mines (USA) Gorp-*$ (Denison's) White Mes^ Urahiura Mill (the site).
in a, Tuesday, May 11 conference call with Denison and in a letter datisd May 26, 2011, UDEQ
expressed concerns Over the adequacy of perched monitoring wells TW4-4, TW4-6, TW4-14, and
TW4-26 to define the chloroform distribution and hydraulic gradients in the viciriity of these wells,
and to establish whether or not chloroform in the vicinity of TW4-6 will be captured by pumping
TW4-4. Figure 1 is aniap showing well locations and the boundaries of the ehlorofprm plume based
on first quarter, 2010 and first quarter, 2011 chloroform data. Note that the southern portion pf the
chloroform plume has been shrinking;
UDEQ believes that at least one additional perched monitoring well downgradient of TW4-4 and
TW4-6is needed. In.itsMay 26,2011 letter, UDEQ requested that Denison submit to theExecutive
Secretary of the State of Utah Radiation Control Board (the Executive Secretary) for approval a pian
of action and work, schedule to complete the installation of one or rriore wells in locations
hydraulically downgradient df wells TW4-4 and TW4-6 to demonstrate the plume is bounded and to
assure that the plume is hydraulically being captured in this vicinity^ The letter also states thati in
conjunction with the existing wells, these new well(s) must show on a map:
• The 70 pg/l chloroform isoconcentration line rerhains hydraulically upgradient to the neiw
well(s); and
« Groundwater contour lines must show the new well(s) are hydraulically downgradient to
TW4-4 and TW4-6.
C
^Sl West VV«nwrc,iuUt 1()J ruL•so^^ Aji/o»^^^ 8o705 I67« ' .=^20193 1500 520:293,l.S.=;0-F3x 8,00.727:6547-Toll i-rcc
David Frydenlund, Esq.
June 17,2011
Page 2
As described in rhore detail below and as explained in our telephone conference. I believe thiat the
existing Wells adequately bound the chloroform plume and that additional wells are not necessary.
However, given UDEQ's request that One or more additional wells be installed, 1 propose that one
additional non-pumpirig chloroform mpnitoring well be instailed at thi s time and that the water level
and chloroform concentration data from that well be used to determine if the criteria referred to
above are satisfied. If after the receipt of at least two quarters of data, Denispn cannot deitioiistrate
that the criteria stated above have been satisfied, Denison wUl at that time be in a position to propose
one or more additional weUs, based on a review of the data generated from^^T^
Overview
Perched monitoring wells TW4r4 and TW4-6 were installed in 2000 to monitor ehibrofortii
concentralions in the downgradient portion of the plume. Concentrations at TW4-4, located
inunediately upgradient (north) of TW4T6, have exceeded 70 jii gyTL since tlie first quarter of2001 and
have remained above 1 (KX) |ig/L. Chlbrofprm concentrations at TW4^6 ranged from non-detect to a
maximum of 52 pg/L between 2000 and the fourth quarter of 2008. Frotn the first quarter of 2009
thrpugh the fourth quarter of 2010 coricentrations at TW4-6 exceeded 70 ng/L. Gohcentratiohs
reached a maximum of 1()00 jig/L in the first quarter of 2010 then began dropping. The
cpiicehtratioh at TW4-6 as bf the first quarter of 2011 is again below 70 pg/L. The coiicentration at
perched well TW4-26, installed at a location presumably downgradient (south) of TW4-6 in May,
2010, was initially 13 pg/L and has dropped to 2 pg/L. Concentrations at TW4-14 and TW4-23,
located east and west, respectively, of TW4-6, have been ridn-deteet since installation ih 2002 and
2007, respectively.
Because of the relatively high chloroform concentrations at TW4-4, and tiie increasing
concentrations atT\V4-6, pumping of TW4-4 was initiated during the first quarter of 201 D tp attempt
to reduce or reverse the increase in Ghlorpform at TW4-6, Pumping at TW4-4 is more practical than
pumping at TW4-6 because the permeability of the perched zone at TW4-6 arid TW4^26 is two
orders of magnitude lower than at TW4T4 {Hydro Geo Chem, 2010. HydrauUc Testing of tW4-4.
TW4r6, and tW4-26, White Mesa Uranium Mill, My 2010), The estiniated sustainable pumping
rates at TW4-6 and TW4-26 are less than 0.1 gallons per ininute (gpm) whereas the estimated
sustainable pumping rate at TW4-4 is 4 gpm. Furthennore, pumping at TW4-6 would act to draw the
higher concentradons detected at TW4-4 downgradient to TW4-6.
Since initiation of pumping at TW4-4 in the first quarter pf 2010, chlprpform concentrations at TW4-
6 have decreased from 1000 ^g/L to 47 pg/L. Since installation in the second quarter of 2010,,
concentrations at TW4-26 have decreased from 13 pg/L to 2 pg/L. Water levels at TW4^6 have not
measurably decreased during this time period, raaking it difficult to assess whether it is within
hydraulic capture of TW4-4. The low permeability of the perched zone at TW4-6 and the decrease in
permeability between TW4-4 and TW4-6 makes slow development of hydraulic capture likely.
Howeyer, it is not necessary to establish hydraulic capture at TW4-6 to reduce concentrations at
TW4-6. It is sufficient only to reduce or cut off the spurce of chloroform to TW4-6 which is the
apparent result of pumping TW4-4 based on the data collected to date.
Ii\7l80()(ftlw27pro[rttw27pr()p_fcv3,dnc
David Frydenlund, Esq.
June 17,2011
Pagei?
With regard to the water levels in the vicinity of TW4-4, there has been a consistently low water
level at TW4-14 (located eastof TW4-4) since installation in 2002, This low water level dominates
water level contours in the vicinity of TW4-4, TW4-6i and TW4-26. As Of the first quarter pf 2011,
the water level in TW4-14 was 12 feet IpWcr than the level in TW4-6, and 19 feet Ipwer than the
level in TW4-4 (even though TW4-4 is pumping). Similarly, in the fourth quarter of 2010, the water
level in TW4-14 was lower than in TW4-6 arid TW4-4 by 13 feet and 9 feet, respectively. Figures 2
and 3 arekriged site^Wide water level contour and estiniated capture zone maps for the first quarter
of 2011 and the fourth quarter of 2010. These figures are identical to those submitted with their
respective Quarterly Chlorofonn Monitoring Reports except thatTW4-6, TW4-14, andTW4-26 are
specifically labeled. Both figures, show closed contours surrounding TW4^ 14 suggesting that TW4-
14 is dbwngradient of TW4-4, TW4-6, and TW4-26. This is illustrated in the attached Figure 4
which is a detail map of the plume area showing p)erehed Waterlcvei contours and flow directions fpr
the first quarter of 2011. The water level at TW4-14 seems anomalous because if this well were
indeed dP wngradient of TW4-4, chioroform would be expected to niigrate frpm TW4-4 tp TW4-14
and hot to TW4r6 arid TW4T26 as has been demonstrated. If the water level data arc kriged without
the water level at TW4-14, the water level contours indicate a perched hydraulic gradient to the
sPuth-southwest, in a directipri ranging frOm sub-parallel to away frOih the eastem property
boundary, as shown in Figure 5.
The water level data presented in Figures 4 and Sindicatelhatregardless of whether the water level
al TW4rl 4 is considered anonialpus, the likelihood that ehlbrofortTi cpuld mpve undetected tpward
the eastem property boundary is minimal. The historical chloroform data indicate that the direction
of perched water flow is to the south or south-soiilhWest froin TW4-4 towards TW4-6 ahd TW4^26,
and not to the southeast tpward TW4-14,
For these reasons, I believe that the existing monitorinjg well network adequately bounds the
chioroform plume and that additional wells are not necessary tp the scutheast of TW4-4 and TW4-6.
At the present time, the data from existing wells in this area seem adequate, especially considefing
the shrinkage of the chloroform plunie that has occurred since TW4-4 pumping began. However, I
realize that UDEQ disagrees with my position on this, and have therefore set out my
recommendations below fpr tlie instailatipn pf pne (pr mpre) additional mpnitoring wells.
Recommendations
In order to address UDEQ's Concems, I recommend the following:
I . Iristallation of TW4-27
One new well (TW4-27) will be installed south of tW4-14 and cast of TW4-6 and TW4-26 (Figure
6). One well at this location is considered adequate to ensure that chldrpform does not move
undetected in an unanticipated easterly direetiPn tpwai'd the eastern prpperty bpundary. TW4-27 Will
be a monitoring well and will not be a pumping well.
HA7 l«IX)0Uw27p™pMw27(>H>p ^S.doi;
David Frydenlund, Esq.
June 17.2011
Page 4
The proposed location for TW4r27 will
a) extend thc current network of easternmost mpnitoring wells to the south,
b) provide additional data to indicate whether the water level at TW4-14 is anomalous, and
c) , provide additibnal data to address UDEQ's concerns about potential eastward migration bf
chloroform.
2. Collection of Additional Water Level and Chloroform Data
Water level and chiprofonn concentration data collected frpm the exisdng wells, and uppn
ccriipletipri frpih TW4-27, will be used tp determine if the addition pf TW4-27 demonstrates tiiat:
d) the 70 pgA ehlorofprm ispcpncentration line remains hydraulically upgradient pf TW4-27;
and
e) grpundwater elevatipns show that tW4-27 is hydraulically downgradient pf TW4-4 and
TW4-6.
3. Possible Abandonment of TW4-14
If the Water level data from TW4-i7 iiidieatc that the water leVel at TW4-14 is anomalous, TW4-14
should be abandohed. The water level at TW4-14 Will be considered miomalous ifthe water level at
TW4-27 is comparable to the water level at TW4-6. One the other hand, if the water level at TW4-27
is comparable to the water level atTW4-14 or if TW4-27 is dry, the waterlevel at TW4-14 will not
be considered anomalous.
4. Installation of Additional Wcll(s) if Necessary
It may take some time fpr the hydraulic system tp adjust to the addi
at least two quarters Of data, the criteria set put in paragraph 2 abpve are npt satisfied, then, Denison
should be in a position to propose a plan and schedule at that time for the location of one or mpre
additional wells, based on the infprmation gained from monitoring TW4-27.
Please feci free to contact me if you have any questipns or cpmments.
Sincerely,
Stewart J. Smith
AssociiUe Hydrogeologist
Attachments (6)
ATTACHMENTS
FIGURES
1 Site Plan and Perched Well Location Map Showing Ql, 2011 and Ql, 2010 Chloroform
Plurnes as Defined by 70 ug/L Boundaries
2 Kriged 1'^ Quarter, 2011 Water Levels and Estimated Capture Zones. White Mesa Site
3 Kriged 1'^ Quarter, 2010 Water Levels and Estimated Capture Zones, White Mesa ^ite
4 Kriged I** Quarter, 2011 Water Level Detail Map Showing Estirnated FIPW Directions
and Ql, 2010 and Ql, 2011 CWpn)form Plume Boundaries
5 Kriged 1'' Quarter, 2011 Water Level Detail Map Generated Exeliidirig TW4-14 and
Showing Estimated FIPW DiTectipns and Ql, 2010 and Ql, 2011 Chlorofortn Plume
Boundaries.
6 Proposed Lpcation pfTW4-27 Showing Kriged Ql, 2011 Water Levels £md 2011 and
Ql> 2010 ChlPrpfonii Plunie Boundaries (Detail Map^^
PROPERTY
BOUNDARY
PlEZ-1
e-
TWN-i
7W4-28
MW-34
EXPLANATION
parched monitoring well
temporary perched monitoring well
perched piezometer
temporary perched nitrate
monitoring well
temporary perched monitoring well
installed May, 2010
perched monitori-ig well installed
August/September, 2010
{ I Ql, 2010 70 ug/L chloroform plume boundary
HYDRO
GEO
CHEM, INC.
SITE PLAN AND PERCHED WELL LOCATION
SHOWING Ql, 2011 AND Ql, 2010 GHLOROFORM
AS DEFINED BY 70 ug/L BOUNDARIES
WHITE MESA SITE
MAP
PLUMES
APPROVED
SJS
OATE' REFERENCE
H:/718000/tw27prop/chlJ 0_11 .Srf
FIGUBE
PROPERTY
BOUNDARY
MW-22
fi 5450
O 5555
PIEZ-1
O 5593
TWN-4
^5604
TW4-26
)»5537
MW-34
•^5492
EXPLANATION
perched monitoring well showing
elevation in feet amsl
temporary perched monitoring well
showing elevation in feet amsl
perched piezometer showing
elevation in feet amsl
temporary perched nitrate monitoring well
showing elevation in feet amsl
temporary perched monitoring well installed
May, 2010 showing eievation in feet amsl
perched monitoring well installed
August/September, 2010
showing elevation tn feet amsl
* 9 I f
estimated capture zone
boundary streann tubes
resulting from pumping NOTE: MW-26, TW4-4, TW4-19 and TW4-20 are pumping wells
HYDRO
GEO
CHEM, INC.
KRIGED 1st QUARTER, 2011 WATER LEVELS
AND ESTIMATED CAPTURE ZONES
WHITE MESA SITE
APPROVED
SJS
DATE FCFEneNCE HV718000/
tw27prop/wl0211cz2_rev1 .srf
FIGURE
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EXPLANATION
7, '/-»/
01. 2011 70 ug/L chlcroform plume boundary
Ql, 2010 70 ug/L chloroform plume boundary
^KKQo^ temporary perched nitrate monitoring 5598 well showing elevation in feet amsl
O "^^'^ temporary perched monitoring well
5555 showing elevation in feet amsl
0 MW-32 perched monitoring well showing
5549 elevation in feet amsl
0 150 300
SCALE IN FEET
NOTE: MW-4. MW-26, TW4-4, TW4-19, and TW4-20 are pumping wells
HYDRO
GEO
CHEM, INC.
KRIGED 1st QUARTER, 2011 WATER LEVEL DETAIL MAP
SHOWING ESTIMATED FLOW DIRECTIONS
AND Q1,2010 AND Ql, 2011 CHLOROFORM PLUME BOUNDARIES
WHITE MESA SITE
APPROVED
SJS Hy718000/
tw27prpp/f lowql _chl .srf
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EXPLANATION
C^^~^ Q1, 2011 70 ug/L chloroform plume bcundary
y Ql, 2010 70 ug/L chlorcf orm plume boundary
^IcQo'^ temporary perched nitrale monitoring 5598 well showing elevation in feet amsl
O TW4-1 temporary perched monitoring well
5555 showing elevation in feet amsl
0 MW-32 perched monitoring well showing
5549 elevation in feet amsl
---if /
^^>^ty
\y-^y
0 150 300
SCALE IN FEET
NOTE: MW>4, MW-26. TW4-4. TW4-19. and TW4-20 are pumping wells
HYDRO
GEO
==i-5r CHEM, INC.
KRIGED 1st QUARTER, 2011 WATER LEVEL DETAIL MAP GENERATED
EXCLUDING TW4.14 AND SHOWING ESTIMATED FLOW DIRECTIONS
AND Q1, 2010 AND Ql, 2011 CHLOROFORM PLUME BOUNDARIES
WHITE MESA SITE
APPROVED
SJS •'^^^ H:/718000/
tw27prppo/flowq1no14_chl.srf
f
EXPLANATION
Q1,2011 70 ug/L
chlorofonm plume t)oundary
^ Q1,2010 70 ug/L
* chloroform plume txjundary
X proposed new
^ well (TW4-27)
0 150 300
SCALE IN FEET
^IKQP"^ temporary perched nitrate monitoring
5598 vvell showing elevation in feet amsl
O ^^/^ temporary perched monitoring well
5555 showing elevation in feet amsl
H MW-32 perched monitoring well showing
5549 elevation in-eet amsl
HYDRO
GEO
CHEM, INC.
NOTE: MW-4, MW-26. TW4-4. TW4-19. and TW4-2G are pumping wells
PROPOSED LOCATION OF TW4-27
SHOWING KRIGED 01,2011 WATER LEVELS AND
01, 2011 AND 01,2010 CHLOROFORM PLUME BOUNDARIES
(Detail Map)
APPROVED
SJS H:/7180Q0/tw27prop/tw27prop.srf