DRC-2010-005045 - 0901a06880361ab7

DRC-2010-005045
DEriiso
MINES
September 15, 2010
VIA PDF AND EXPRESS DELIVERY
Rusty Lundberg, Co-Executive Secretary
Utah Water Quality Board
Utah Department of Environmental Quality
195 North 1950 West
P.O. Box 144810
Salt Lake City, UT 84114-4820
Oonisoii MiiMS (USA) Corp.
ION 17th Street, Suito 950
Oenvsr, CO 8026S
USA
Tel: [phone]S
Fax: [phone]
wwrw.denlsotiiiiiiies.coin
Dear IVIr. Lundberg:
Re: State of Utah Ground Water Discharge Permit No. UGW370004 White Mesa Uranium Mill - Notice
Pursuant to Part I.G.3 of the Permit and UAC R317-6-6.16(C)
Please take notice pursuant to Part I.G.3 of the White Mesa jVlill's (the "Mill's") State of Utah Groundwater
Discharge Permit No. UGW370004 (the "Permit") and Utah Administrative Code ("UAC") R313-6-6.16(C) that
Denison Mines (USA) Corp. ("Denison"), as operator of the Mill and holder of the Permit, failed to meet the
discharge minimization technology ("DMT") standards in Part l.D.2 of the Permit, by allowing the wastewater
elevation in the Mill's tailings Cell 3 to exceed the freeboard limit for that Cell by approximately 2.12 feet, as
described in more detail below.
This exceedance was discovered at 1:50 pm on Friday September 10, 2010. Initial notice of this failure to
maintain DMT was given by telephone to the Utah Department of Environmental Quality ("UDEQ") by phone call
to the After Hours Reporting Line at 2:40 pm on Friday September 10, 2010 within 24 hours of discovery.
1. Facts and Background Information
a) Condition 10.3 of the Mill's State of Utah Radioactive Materials License No. UTl900479 (the
"License") provides that the freeboard limits for Cell 1 shall be set in accordance with procedures that
have been approved by the U.S. Nuclear Regulatory Commission ("NRC"). Under those procedures
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").
Condition 10.3 of the License also provides that the freeboard limit for Cells 3, 4A and 4B shall be
recalculated annually in accordance with the procedures approved by the Executive Secretary of the
state of Utah Radiation Control Board. The current freeboard limit for Cell 3 was previously
calculated under this procedure at 5,601.6 fmsl. However, in UDEQ correspondence dated
November 20, 2008 an interim variance and limit was established at 5,602.5 fmsl for Cell 3.
Notice to Rusty Lundberg on Cell 3 Freeboard
September 15, 2010
Page 2
In conjunction with the variance established under (ii) above, an interim maximum elevation for Cell
4A was also established at 5,593.74 fmsl. Cell 4B is under construction at this time, and a freeboard
limit has not yet been determined for that cell.
The maximum elevation of 5,593.74 fmsl for Cell 4A has been set assuming that the total probable
maximum precipitation ("PMP") volume for Cells 2, 3 and 4A will be accommodated in Cell 4A. By
letter dated December 11, 2008, Denison applied for an amendment to the License to set the
freeboard limit for Cell 4A at 5,593.74 fmsl 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 to accommodate the total PMP
volume for Cells 2, 3 and 4A.
In addition. Part l.D.2 of the Permit provides that under no circumstances shall the freeboard of any
tailings cell be less than three feet, as measured from the top of the flexible membrane liner ("FML").
The top of the FML in Cell 1 is at 5,618.5 fmsl, and the top of the FML in Cell 3 is at 5,608.5 fmsl.
This means that Part l.D.2 of the Permit provides a secondary requirement that the maximum
wastewater pool elevations in Cells 1 and 3 cannot exceed 5,615.5 and 5,605.5 fmsl, respectively.
b) In a letter to Denison dated April 29, 2010, UDEQ has indicated their agreement with Denison's
position that the freeboard limit is not applicable to Cell 3, since Cell 3 is in pre-closure stages, and
the PMP flood volume of Cell 3 can be attributed to, and managed in. Cell 4A. The April 29 letter
indicated that to formalize this removal of freeboard limit, Denison needed to provide revisions to two
documents, specifically the Discharge Minimization Technology ("DMT") Plan, and the Cell 4A
Operations and Maintenance ("O&M") Plan. The requested revisions to both the DMT Plan and O&M
Plan were submitted on August 4, 2010. To date, UDEQ has not completed its review of these
documents.
c) The Mill experienced a significant rainfall, of more than one inch in under an hour, on Wednesday
September 8, 2010.
d) During the weekly tailings survey measurement performed at approximately 1:50 pm on Friday
September 10, 2010, the wastewater pool elevation in Cell 3 was measured to be 5604.62 fmsl,
compared to the current freeboard limit for Cell 3 of 5,602.50 fmsl, representing an exceedance of
2.12 feet, or 25.44 inches.
e) It should be noted that the current freeboard limit 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 current freeboard limit by 2.12 feet (25.44 inches)
resulted in a wastewater pool elevation that was still nearly four feet below the top of the FML and
still below the secondary freeboard limit of 5,605.5 feet set out in Part l.D.2 of the Permit. As a result,
there was no risk of the wastewater in Cell 3 overflowing over the top of the Cell 3 FML. Also, as
mentioned above, since the freeboard limit in Cell 4A has been set 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 not
have been adequate freeboard available in Cell 4A. The wastewater elevation survey for Cell 4A
performed on September 10, 2010 indicated a wastewater elevation 64.08 inches (5.34 feet) below
the freeboard limit of 5,593.74 fmsl for Cell 4A.
f) The Mill has been running on a 10-days on and 4-days off operating cycle. The 4-days off cycle had
already commenced when the Mill shut down on Friday morning September 10, 2010.
DENISOl
MINES
Notice to Rusty Lundberg on Cell 3 Freeboard
September 15, 2010
Page 3
g) Cell 3 is approaching its final stages of pre-closure and is almost full. As part of the plan to fill Cell 3
with tailings solids and to close Cell 3, the Mill has been alternating between periods of pumping Cell
3 liquids into Cell 4A and discharging CCD solids into Cell 3. The intention was to discharge tailings
solids into Cell 3 at a rate that, given the rate solutions were being pumped from Cell 3 to Cell 4A,
would not result in an exceedence of the freeboard limit in Cell 3. Earlier in 2010, the Mill staff had
replaced the existing pump in Cell 3 with a new pump to increase the flow rate of solutions from Cell
3 to Ceil 4A during the liquid transfer cycle.
h) Cell 3 was receiving only CCD solids and solutions from the Cell 2 slimes drain at the time of the
exceedence.
i) Transfer of CCD solids into Cell 3 had already stopped before the freeboard level was surveyed and
the freeboard exceedance identified at 1:50 PM on Friday September 10, 2010.
j) Transfer of liquids from Cell 3 to Cell 4A had begun on Wednesday September 10, 2010, and was
already in progress before the freeboard level was surveyed and the freeboard exceedance identified
at 1:50 PM on Friday September 10, 2010.
2. Action Taken
Upon receipt of the initial survey results, the Mill's Environmental Coordinator notified the Mill Manager at
1:55pm that day. The following plan of action was immediately put into place:
a) The transfer pump from Cell 3 to Cell 4A has been on and remains on in an effort to reduce the liquid
level;
b) Transfer of CCD solids into Cell 3 resumed with the restart of the Mill on Tuesday September 14,
2010. Transfer of solutions from Cell 3 will continue at maximum rate, which exceeds the rate of
inflow into the cell, through the next 10-day Mill run or until the Cell 3 level returns to compliance
level.
c) Verbal notification was given to UDEQ's After Hours Reporting Number at 2:40 pm on September 10,
2010, within 24 hours after discovery of the event. The verbal notification was followed by this written
notification within five days of discovery;
d) Compliance is expected to be achieved during the week of September 20, 2010, barring another
significant rainfall.
3. Root Cause
The root cause analysis is as follows
a) The Mill has been alternating between continually pumping Cell 3 liquids into Cell 4A, while
discharging CCD solids into Cell 3 during the Mill's operating periods.
b) Cell 3 was receiving no tailings solutions at the time of the exceedance. The Mill continues to pump
solutions from Cell 3 to Cell 4A before and while solids are introduced into Cell 3, in an effort to
maintain the solution level in Cell 3 below the freeboard limit during this process.
DENISOl
MINES
Notice to Rusty Lundberg on Cell 3 Freeboard
September 15, 2010
Page 4
c) As a result of following the planned program of filling Cell 3 for closure, the remaining pond area in
Cell 3 has shrunken to approximately 3 to 5 acres, and is continually being reduced by the planned
expansion ofthe solids beach as Cell 3 approaches its final tailings capacity.
d) The Mill site received a significant rainfall two days prior to the exceedance.
e) As a result of the decreasing pond area, the ability to manage the freeboard level has become
increasingly difficult, particularly in periods of rapid rainfall.
f) Upon review of the circumstances, after the discovery of the exceedance, it is again evident that it is
no longer possible to manage the Cell 3 freeboard to achieve the calculated freeboard limit during the
final stages of filling Cell 3 with solids and closing Cell 3. The exceedence occurred despite the fact
that monitoring and surveying were performed at the required frequency, all pumping equipment was
operating properly, and the liquid transfer from Cell 3 to Cell 4A was occurring as planned.
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; and
b) Denison completed and submitted on August 4, 2010 all required draft revisions to the documents
identified in UDEQ's April 19, 2010 letter, to document the elimination of freeboard limits for Cell 3.
To date, UDEQ has not completed its review of the August 4, 2010 submittal of revised documents or
confirmed the removal of the freeboard limit.
5. Affirmative Defense
Denison believes that the affirmative defense in Part I.G.3.c) of the Permit should be applicable to this incident,
for the following reasons;
a) Notification
By virtue of the initial oral notification given to the UDEQ Duty Officer at 2:40 pm on September 10, 2010, and
this written notice, Denison has submitted notification according to UAC R317-6-6.13.
b) Failure Was Not Intentional or Caused by the Permittee's Negligence
The exceedance of the freeboard limit was not intentional or caused by Denison's negligence, either in action or
in failure to act. The Mill was taking actions to manage the freeboard requirements of all of its active tailings
cells while filling Cell 3 to its final tailings solids capacity in preparation for closure. Based on a survey of the
wastewater elevation in Cell 3 taken the week of Friday September 3, it appeared that there was ample
freeboard in Cell 3. The fact that the water level in Cell 3 increased at an unexpectedly fast rate was due to a
combination of the planned discharge of CCD solids into Cell 3, a significant rainfall the week of the
exceedance, and the difficulty of managing liquids in a pool of decreasing size as the solids fill the cell. This
discharge, and the pool's size reduction, are necessary to complete the filling and closure of the Cell.
DENISO
MINES
Notice to Rusty Lundberg on Cell 3 Freeboard
September 15, 2010
Page 5
c) The Permittee has Taken Adequate Measures to Meet Permit Conditions
Denison has taken adequate measures to meet Permit conditions in a timely manner. Solutions are being
pumped from Cell 3 to the Cell 4A at a rate faster than CCD solids are being added to Cell 3.
d) The Provisions of UCA 19-5-107 Have Not Been Violated
The provisions of Utah Code 19-5-107 have not been violated. There has been no discharge of a pollutant into
waters of the state. 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 tailings impoundments, and there was ample freeboard in
Cell 4A to accommodate the PMP for Cells 2, 3, and 4A.
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: Rich Bartlett
David C, Frydenlund
Ron F. Hochstein
Harold R. Roberts
David E. Turk
Kathy Weinel
DENISO
MINES