DRC-2010-002730 - 0901a06880177e82

DENISO
MINES
J>h DRC-2010-QQ273.Q'
1050 17th Street, Suite 950
Denver, CO B0265
USA
Tel : [phone]
Fax; 303 389-4125
w w w.deni son mines.com
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March 31, 2010
VIA PDF AND UPS
Dane L. Finerfrock, Co-Executive Secreiary
Utah Water Qualily Board
Ulah Department of Environmental Quality
168 Norlh 1950 West
P.O.Box 144810
Sait Lake City, UT 84114-4810
ed -' Becew :\
Dear Mr. Finerfrock:
Re: State of Utah Ground Water Discharge Permit No. UGW370004 White Mesa
Uranium Mill - Notice Pursuant to Part I.G.3 ofthe Perniit and UAC R317-6-6.16(C)
Please take notice pursuant to Part i.G.3 of lhe White Mesa MiiKs (the "Mill's") Slate of Ulah
Groundwater Discharge Permii No. UGW370004 (the "Permit") and Utah Administrative Code
("UAC") R313-6-6.16(C) that Denison Mines (USA) Corp., as operator of the Mill and holder of
the Permit, failed to meet the discharge minimization technology ("DMT") standards in Part
I.D.2 of the Permit, by allowing the wastewater elevalion in the Mill's tailings Cell 3 to exceed
the freeboard hmit for that Ceil by approximately 0.36 inches, as described in more detail below.
This exceedance was discovered at 10:00am on Friday March 26, 2010. hiitial notice of this
failure to maintain DMT was given by telephone to the Utah Department of Environmental
Quaiity Duty Officer at 5:05pm on Friday March 26, 20i0 at 801-536-4123 (within 24 hours of
the discovery),
1. Facts and Background Information
a) Condilion 10.3 of the Mill's State of Utah Radioactive Materials License No.
UTI900479 (the "License") provides that freeboard limits for Cells 1 and 3 shall be set
in accordance wilh procedures thai have been approved by the U.S. Nuclear Regulatory
Commission ("NRC"). Under those procedures:
(i) The freeboard limits are set as per the January 10, 1990 Drainage Report for Cell
1 at a liquid maximum elevation of 5,615.4 feet above mean sea level ("fmsl");
(ii) The freeboard limit for Cell 3 is determined annuaUy using a formula set out in
the procedure. The current freeboard limit for Cell 3 was previously calculated
under this procedure at 5,601.6 fmsl. However, in Slate of Utah Department of
Environmenlal Qualily ("UDEQ") correspondence dated November 20, 2008 an
interim variance and limil was eslablisiied at 5,602.5 fmsl for Ceil 3;
(iii) In conjunction with the variance established under (ii) above, an interim
maximum elevation for Cell 4A was also established at 5,593.74 fmsl;
(iv) The maximum elevation of 5,593.74 fmsl for Cell 4A has been sel assuming lhat
the total probable maximum precipitation ("PMP") volume for Cells 2, 3 and 4A
will be accommodated in Cell 4A. By letter daled December 11, 2008, Denison
applied for an amendment to the License to set the freeboard limit for Cell 4A at
5,593.74 fm.sl and to eliminate the need to set a freeboard limit for Cell 3, given
that the freeboard limit of 5,593.74 fmsl for Cell 4A is adequate lo accommodate
the total PMP volume for Cells 2, 3 and 4A; and
(v) in addition. Part I.D.2 of the Permit provides that under no circumstances shall tlie
freeboard of any tailings cell be less than three feet, as measured from the top of
the flexible membrane liner ("nvIL"). The top of die FML in Cell 1 is at 5,618.5
fmsl, and the top of the FML in Cell 3 is al 5,608.5 fmsl. This means that Pan
I.D.2 of the Permit provides a secondary requirement that the maximum
wastewater pool elevations in Cells I and 3 cannot exceed 5,615.5 and 5,605.5
fmsl, respectively.
b) During the weekly tailings inspection perfonned at approximately 10:00am on March
26, 2010, Cell 3 was observed visually to be high in elevation compared to the previous
week. When tlie elevation survey was performed al 10:15am on March 26, 2010, this
observation was confirmed. The sur\'ey results indicated a wastewater pool elevation
of 5,602.53 fmsl, compared to the curreni freeboard limit for Cell 3 of 5,602.50 fmsl,
representing an exceedance of 0.03 feet, or 0.36 inches.
c) It should be noted that the current freeboard liniit in Cell 3 of 5.602.5 fmsl is 6 feet
below the top of the FML in Cell 3, so the exceedance of the cunent freeboard limit by
0.36 inches resulted in a wastewater pool elevation that was still over five feel below
the lop of the FML and over two feel below the secondary freeboard limit of 5,605.5
feel sel out in Part I.D.2 of the Permit. As a result, there was no risk of the wastewater
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in Cell 3 overflowing over the top of the Cell 3 FML. Also, as mentioned above, since
the freeboard limil in Cell 4A has been sel to accommodate the PMP event for Cells 2,
3, and 4A, there was also no risk that even if a PMP event were to occur there would
nol have been adequate freeboard available in Cell 4A. The wastewater elevation
survey for Ceil 4A performed on March 26, 2010 indicated a wastewater elevation 117
inches (9.75 feet) below the freeboard limil of 5,593.74 fmsl for Cell 4A.
d) During the weekly tailings inspection on March 12, 2010, the liquid level in Cell 3 was
at least 1 inch below the freeboard limit for that cell. As part of the plan lo fill Cell 3
with tailings solids and lo close Cell 3, the Mill has been pumping Cell 3 liquids into
Cell 4. In anticipation of the upcoming ore run, the Mill continued to pump the liquids
from Cell 3 inlo Cell 4A and ceased all discharges of tailings solulions into Cell 3.
e) The Mill restarted on March 15, 2010.
0 By the time of the weekly tailings inspection on March 19, 2010, Cell 3 liquids had
been pumped to Cell 4A for over a month, and the Cell 3 liquid level was at leasl 7
inches below the freeboard limil.
g) Discharge of CCD solids to Cell 3 started on March 23, 2010. The intention was to
discharge tailings solids into Cell 3 at a rate that, given the rale solutions were being
pumped from Cell 3 to Cell 4A, would not result in an exceedence of the freeboard
limit in Cell 3. Mill staff had replaced the existing pump in Cell 3 to increase the flow
rate of solutions from Cell 3 to Cell 4A. The new pump was in operation up until the
moming of the exceedence.
h) Cell 3 was receiving only CCD solids and solulions from the Cell 2 slimes drain, and
Cell 4A was receiving all other tailings liquids, at the time ofthe exceedence.
2. Action Taken
Upon receipt of the initial survey results, die Mill's Environmental Coordinator notified the Mill
Manager at 10:30am that day. The following plan of action was immediately put inlo place in
accordance with section 5.1 ofthe Mill's Contingency Plan:
a) The Mill Manager had operations crews stop the discharge of CCD solids into Cell 3;
b) The Mill Manager had the Maintenance Department confirm that die transfer pump
from C^ell 3 to Cell 4A was operational, although it has lost its prime and was not
operating at the time;
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c) This plan was implemented by 11:00am on Friday March 26, 2010;
d) Verbal notificaiion was given to the Executive Secreiary al 5:05pm on March 26, 2010,
within 24 hours of discovery. This verbal notification was followed by this written
notification within five days of discovery;
e) Solutions continued to be pumped from Cell 3 lo Cell 4A in order to reduce the
solution in Cell 3; and
f) Compliance was achieved on March 30, 2010, when a survey of Cell 3 indicated a
solution elevation of 5601.91 fmsl.
3. Root Cause
The rool cause analysis is as follows
a) In an effort to prepare Cell 3 for closure, the Mill has been transferring free liquids
from Cell 3 to Cell 4A for over a month. As a result of the liquid transfer, by March
19, 2010, the Mill had succeeded in achieving a liquid level in Cell 3 lhat was 7 inches
lower than the freeboard limit, so there was no concern that solution levels in Cell 3
were close to the freeboard limit.
b) The Mill restarted on March 15, 2010. Discharge of CCD solids to Cell 3 started on
March 23, 2010. Cell 3 was receiving only CCD solids, and Cell 4A was receiving all
tailings liquids at the time of the exceedence. Solutions continued to be pumped from
Cell 3 to Cell 4A as solids were being introduced into Cell 3, in an effort to maintain
die solution level in Cell 3 below the freeboard limil during this process.
c) As a result of following the plamied program of filling Cell 3 for closure, the remaining
pond area in Cell 3 is small, approximately 7 to 10 acres, and is continually being
reduced by the planned expansion of the solids beach as Cell 3 approaches ils final
tailings capacity.
d) As a resuh of the ever-decreasing pond area, the ability to manage the freeboard level
has become increasingly difficult.
e) Upon review of the circumstances, after the discovery of the exceedance, it has become
obvious that it may no longer be possible to manage the Cell 3 freeboard lo achieve the
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calculated freeboard limil during the final stages of filling Cell 3 with solids and
closing Cell 3. The exceedence occurred despite the fact that moniloring and surveying
were perfonned at the required frequency, all pumping equipment was operating
properly, and the liquid transfer from CeU 3 to Cell 4A was occurring as platmed.
4. Actions That Will be Taken to Prevent a Reoccurrence of this Incident
The following actions will be taken to prevent a reoccurrence of this incident:
a) The Mill will continue to pump liquids from Cell 3 to Cell 4A, in preparation for
dewatering and closure of Cell 3;
b) UDEQ is asked to complele its review of Denison's request for License and Permit
amendments lo eliminate the freeboard limil in Cell 3, given the ample freeboard limit
set in Cell 4A.
c) Denison will apply for an inierim variance to eliminate the freeboard requirement in
Cell 3 pending UDEQ's review of the foregoing license and permit amendment
requests, on the basis that the freeboard limil in Cell 4A has been set to accommodate
the PMP event for Cells 2, 3, and 4A.
5. Affirmative Defense
Denison believes that die affirmative defense in Part LG.3.c) ofthe Permit should be applicable
to this incident, for the following reasons:
a) Notificaiion
By virtue of the initial oral notification given lo the UDEQ Duty Officer at 5:05pm on Friday
March 26, 2010 (within 24 hours of Uie discovery) and this written notice, Denison has
submitted notification according to UAC R317-6-6.13.
b) Failure was not Intentional or Caused by the Pennittee's Negligence
The exceedance of the freeboard limit was nol intentional or caused by Denison's negligence,
either in action or in failure lo act. The Mill was taking actions to manage the freeboard
requiremenis of all of ils active tailings cells while filling CeU 3 to its final tailings solids
capacity in preparation for closure. Based on a .survey of the wastewater elevalion in Cell 3 laken
the previous week, it appeared that there was ample freeboard in Cell 3, and, based on past Mill
experience it was not unreasonable for Mill staff to come to lhat conclusion. The fact that the
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water level in Cell 3 increased at an unexpectedly fast rate was due to the plamied discharge of
CCD solids into Cell 3 coupled with the issue of managing liquids in a pool of ever-decreasing
si/.e as the solids fill the cell. This discharge, and the pool's size reduction, are necessary to
complete Uie filling and closure of the Cell.
c) The Permittee has Taken Adequate Measures to Meet Permii Conditions
Denison has taken adequate measures lo meet Permii conditions in a timely manner. The
provisions of the Mill's Contingency Plan were implemented immediately, and tlie wastewater
levels have been brought back to within the freeboard limits.
d) The Provisions of UCA 19-5-107 Have Nol Been Violated
The provisions of Utali Code 19-5-107 have not been violated. There has been no discharge of a
poUutant inlo waters of the stale. Denison has not caused 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, nor has Denison placed or
caused to be placed any waste in a location where there is probable cause to believe it will cause
pollution.
There was no discharge of solutions from the Mill's ladings impoundments, and there was ample
freeboard in Cell 4A lo accommodate the PMP for Cells 2, 3, and 4A.
Please conlact Uie undersigned if you have any questions or require any further information.
Yours truly.
Jo Ann Tischler
Director, Compliance and Permitting
cc: David C, Frydenlund
Ron F. Hochstein
Ryan Palmer
Harold R. Roberts
David E. Turk
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