DRC-2012-001425 - 0901a068802d308f

DENISON
MINES
Dii Denison Mines (USA) Corp
1050 17th Street, Suite 950
Denver, CO 80265
USA
Tel [phone]
Fax [phone]
www denisonmines com
May 4, 2012
VIA E-MAIL AND OVERNIGHT 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 84114-4810 DRC- 2012-00 U25
Re: State of Utah Ground Water Discharge Permit No. UGW370004 White Mesa Uranium Mill -
Notice Pursuant to Section 1.11(1) of the Spill Prevention, Control, and Countermeasures Plan
and UAC 19-5-114: Response to Claricone Solution Spill
Dear Mr Lundberg
Please take notice pursuant to Section 1 11(1) of the White Mesa Mill's (the "Mill's") Spill Prevention, Control,
and Countermeasures ("SPCC") Plan and Utah Administrative Code ("UAC") 19-5-114 that Denison Mines
(USA) Corp ("Denison"), as operator of the Mill and holder of the Permit, incurred a spill of process fluids
resulting from failure of the Claricone tank as described below
The Claricone breakdown and spill was identified at approximately 12 50 pm on Thursday April 12, 2012
Initial notice of this spill incident was given by voice mail and email to the Executive Secretary of the Utah
Department of Environmental Quality at 3 45 pm on Thursday Apnl 12, 2012 at 801-536-4025 (within 24
hours of the discovery) Dunng a subsequent phone call from DRC to Denison at approximately 4 30 pm on
Apnl 12, 2012, Denison provided details of the incident to Mr Phil Goble
1. Notification of the Spill
a) The Clancone is a 29 1/2 foot diameter fiberglass conical separator cone which was located (both
physically and process-wise) between the uranium leach circuit and the solvent extraction circuit
The Claricone contained approximately 28,000 gallons of solution containing water, sulfunc acid and
uranium salts At the time of the incident descnbed below, the Claricone was estimated to contain
approximately 420 gallons or 6,460 lbs of sulfunc acid, and approximately 190 lbs of uranium in an
aqueous solution at ambient temperature
b) The Clancone was installed on a concrete pedestal which, along with the bottom third of the vessel,
was below ground and stabilized with soil backfill The bottom valves and piping, consisting of high
density polyethyene ("HDPE") and polyvinyl chlonde ("PVC") pipes, were accessible though a
horizontal conduit The 4-foot diameter horizontal conduit referred to as the "Claricone Underflow
Tunnel", installed below grade, served as an access to the concrete pedestal and bottom piping The
N \Claricone failure 04 11 12\Final Claricone Notification 05 04 12\05 04 12 Letter to RLundberg Clancone Status and Plan
Final doc
Letter to Mr Rusty Lundberg
May 4, 2012
Page 2
honzontal conduit joined a vertical conduit section which exited to the ground surface The Claricone
Underflow Tunnel was accessed through a ladder in the vertical section Access to the Claricone
Underflow Tunnel required procedures for confined space entry Access to the top of the vessel was
via a steel walkway
c) At 1 50 pm on Apnl 12, 2012, the Claricone leaked its contents into the Claricone Underflow Tunnel
beneath the ground surface Some portion of the contents in the horizontal portion of the Claricone
Underflow Tunnel leaked out through breaks into the surrounding soils The Mill supenntendent, near
the vessel at the time of the failure, observed solution rising to the ground surface, and a collapse of
surface soils into an apparent sink hole, above the honzontal section of the Clancone Underflow
Tunnel
d) Section 1.11 (1) of the SPCC Plan requires that Denison
I Report spills to applicable government agencies as required by applicable laws and
regulations, and
II Perform cleanup in accordance with Section 1 8 of the SPCC Plan.
e) Corporate environmental management determined on April 11, 2012 that notification to DRC of the
failure and the resulting spill was required under Section 1 11(1) of the SPCC Plan and UAC 19-5-
114
f) Denison provided email and voice mail notice to the Executive Secretary at 3 45 pm Apnl 12, 2012
and detailed information to Phil Goble of DRC at 4 30 pm on Apnl 12, 2012, within 24 hours of
discovery This verbal notification was followed by this written notification submitted within the time
frame committed to in phone conversations and email correspondence with DRC on April 19, 2012,
and Apnl 23, 2012
g) For conservatism, Denison estimated the volume of the entire contents of the Clancone spill, and the
sulfuric acid content of the entire Clancone volume, in order to assess whether a Reportable Quantity,
of sulfunc acid, as defined in the Mill's Storm Water Best Management Practices Plan, and SPCC
Plan, had been spilled Denison's conservative estimate was that 420 gallons, or 6,460 lbs, of
sulfunc acid were spilled Denison reported this quantity to DRC in the phone call of 4 30 pm Apnl
12, 2012, along with the additional information that potentially approximately half of the spilled
matenal had not entered the environment and remained within the Clancone Underflow Tunnel This
estimate has since been modified based on additional data collected during the response and
cleanup It is currently estimated that approximately 219 gallons of sulfunc acid were spilled to the
environment
Denison also reported that maintenance was in the process of attempting to remove the solutions
from the Claricone Underflow Tunnel via portable pump, and the recoverable volume of solution was
as yet unknown DRC instructed Denison to proceed with the spill response and removal action,
attempt to confirm the volume of process matenal pumped to Roberts Pond or removed by other
means, and to prepare a plan for the Executive Secretary addressing actions to date, and planned
cleanup actions
DENISON
MINES
Oii
Letter to Mr Rusty Lundberg
May 4, 2012
Page 3
2. Containment Procedures/Actions Taken to Date
The following is summary of containment actions to date
Wed 4/11/12 • Solution flows to Claricone shut off approximately 1 55 pm
upon first identification of failure
• Remaining solution in the Clancone was pumped out to
Roberts Pond
Thurs 4/12/12 • Solution pumped from vertical shaft of tunnel
• Clancone inspected from above
Fn 4/13/12 • RSO entered vertical shaft of tunnel The RSO's inspection
identified that horizontal section of tunnel was filled with
sediment/mud and was inaccessible
• Clancone stabilized by chains and lift straps on crane
• Removal of contaminated soil by backhoe and mini-
excavator, and disposal in Cell 3, began
• Removal of tunnel horizontal section and disposal in Cell 3,
began
Sat 4/14/12 No Activity
Sun 4/15/12 • Removal of contaminated soil by backhoe and mini-
excavator, and disposal in Cell 3, continued
Mon 4/16/12 • Removal of contaminated soil by backhoe and mini-
excavator, and disposal in Cell 3, continued
Tue 4/17/12 • Removal of contaminated soil by backhoe and mini-
excavator, and disposal in Cell 3, continued
• Removal and disposal of Clancone in Cell 3 began
Wed 4/18/12 • Rented trackhoe arnves at Mill Excavation by trackhoe
began
Thurs 4/19/12 • Excavation by trackhoe continued through the week of
4/22/12
Thurs 4/26/12 • Excavation and scanning for radiological confirmation was
completed
3. Estimation of Spill Volume
The first observation of the Claricone from above the vessel following the incident indicated that no more than
15 gallons remained in the bottom of the cone after the spill
On Friday, April 13, 2012, maintenance attempted to transfer the remaining free liquid solutions from the
Claricone Underflow Tunnel to Roberts Pond The pumping attempt identified that only a small volume of
matenal remained as free liquid, with the majority bound in saturated mud in the tunnel and affected soil area
The transfer pump operated at 70 gpm for approximately 30 minutes, transferring an estimated 2100 gallons
of solutions to Roberts Pond The water-saturated mud could not be moved by the liquid pump
The Clancone Underflow Tunnel was completely filled with mud when it was removed by crane and
transferred to Cell 3 for disposal The volume of mud contained in the tunnel was approximately 11,280
gallons
DENISON
MINES
Dii
Letter to Mr Rusty Lundberg
May 4, 2012
Page 4
Attachment 1 provides an estimate of the volume of solutions, and mass of sulfunc acid, from the spill that
may have reached the surrounding soil Attachment 2 provides photographs depicting the conditions at the
time of and following the spill
4. Procedure for Cleanup and Disposal
The Mill has performed cleanup and disposal of contaminated media from the spill as follows
a) The Clancone, and the horizontal and vertical sections of the Claricone Underflow Tunnel, have been
taken out of service, excavated and lifted from their in-ground locations, cut up for transport, and
disposed in Cell 3
b) Contaminated solutions were pumped to the extent possible from the Claricone and the Claricone
Underflow Tunnel Pumped solutions were transferred to Roberts Pond
c) Contaminated soil was removed and disposed in Cell 3 The extent of soil removal addressed both
chemical and radiological contamination
a All soils visibly wet, stained or discolored were excavated until uncontaminated dry
background soils remained
b The bottom and sides of the excavation were scanned by microR meter (measunng residual
gamma contamination) When the bottom or sides of the excavation indicate gamma levels
greater than background levels, the excavation was resumed, additional contaminated soil
was removed, and the bottom and sides of the excavation were re-scanned until all surfaces
result in gamma levels less than or equal to cleanup background (Cleanup background was
defined as two times the average of four measured background readings taken as described
in Attachment 3 This approach accounted for the contnbution to background of gamma
radiation from other nearby process equipment such as the clanfier, thickener, and CCD
impounds ) When the bottom and sides of the excavation indicated gamma levels of less than
cleanup background as defined above, the excavation was considered complete, and the
area was prepared for backfill and re-grading
A gamma survey was considered to be suitable because the spilled Clancone solutions contained appreciable
concentrations of gamma-emitting radionuclides
Based on the above method, a total estimated volume of 1,134 cubic yards was removed and disposed in
Cell 3, along with the Claricone vessel, tunnel, and associated piping
Attachment 3 provides a summary report of radiological measurements used to assess measured background
and confirm completion of the excavation
5. Root Cause Analysis
On Apnl 13, 2012, after it was determined the mud deposited in the Claricone Underflow Tunnel could not be
removed by pumping, Mill maintenance personnel removed the Clancone Underflow Tunnel in order to
access the bottom of the cone Inspection of the bottom of the cone, and subsequent activities on April 16
and 17, 2012 to remove the cone from its setting by lifting with a crane, identified that the Claricone had
DENISON
MINES
Dii
Letter to Mr Rusty Lundberg
May 4, 2012
Page 5
expenenced a fracture of the cone bottom which released the vessel contents into the Claricone Underflow
Tunnel The velocity of the sudden release of fluids into the Clancone Underflow Tunnel resulted in fractures
of the Claricone and underflow piping, the tunnel at the horizontal/vertical conduit connection, and the
honzontal portion of the tunnel at several locations
There appeared to be three points of matenal release to the environment, as follows
1 A portion of the matenal was released from breakage at the buried base of the Clancone bottom,
approximately 9 feet below ground surface ("bgs")
2 The sudden discharge of Clancone contents into the Clancone Underflow Tunnel appears to have
ruptured the tunnel at several points, discharging matenal to the subsoil from 5 feet bgs to 9 feet bgs
3 Some of the matenal which entered the Claricone Underflow Tunnel flooded the vertical shaft, exited
the top of the shaft, and entered into the dram pan to Roberts Pond A portion of this matenal
overflowed the drain pan to the ground surface
Material discharged through paths 1 and 2 seeped upwards towards the ground surface, saturating surface
soils, and resulting in the collapse noted by the Mill Superintendent
6. 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
The Claricone has been removed from service The process piping between the leach circuit and solvent
extraction circuit will be modified to eliminate the need for this process step or piece of equipment in the short
term Replacement options will be evaluated by Mill Management if this process step is required in the longer
term
7. Compliance with SPCC Plan
In satisfaction of Part ID 10 of the Mill's Groundwater Discharge Permit, the spill was controlled in
accordance with the currently-approved SPCC Plan The Mill's SPCC Plan, in Section 1 8, "Spill Discovery
and Remedial Action" requires the following steps be completed in response to a spill Each step is listed in
Italics followed by confirmation of how the step was implemented dunng the Clancone spill response
"Chemical or petroleum spills will be handled as follows
The Shift Foreman will direct efforts to shut down systems, is possible, to limit further releases "
• The Clancone fill valves and influent flows were shut off immediately after the failure was identified
"The Shift Foreman will also secure help if operators are requinng additional assistance to contain the spill"
• The Shift Foreman and Mill Supenntendent mobilized a multiple operator crew for response when the
failure was identified Additional crew were mobilized for the ongoing cleanup effort beginning the day
after the incident
DENISON
MINES
Dii
Letter to Mr Rusty Lundberg
May 4, 2012
Page 6
"The Shift Foreman is also obligated to initiate reporting procedures Once control measures have begun and
personal danger is minimized, the Shift Foreman will notify the Production Supenntendent, l\/1aintenance
Supenntendent, or Mill Manager."
• Internal reporting to the Superintendents and Mill Manager occurred immediately The Production
Supenntendent was present near the equipment at the time of the incident and participated in the
notifications
"The Production or Maintenance Supenntendent will notify the Mill Manager, who in turn will notify the
Department Head of EA/HS and/or the Environmental Coordinator "
• The Mill Manager designated the RSO to contact Corporate Environmental management Notification
to the Corporate Director, Compliance and Permitting occurred within one hour of the incident
"The Mill Manager will assess the spill and related damage and direct remedial actions The corrective
actions may include repairs, cleanup, disposal, and company notifications. Government notification may be
necessary in some cases "
• Corrective actions were implemented as described in Sections 2 and 4, above Notification of the
Executive Secretary occurred as descnbed in Section 1, above
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- Dan Hillsten
Ron Hochstein
David C Frydenlund
Harold R Roberts
David E Turk
Central files
DENISON
MINES
Dii
Letter to Mr Rusty Lundberg
May 4, 2012
Page 7
ATTACHMENT 1
ESTIMATION OF SPILL VOLUME
DENISON
MINES
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May 4, 2012
Page 8
ATTACHMENT 2
PHOTOGRAPHS
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May 4, 2012
Page 9
ATTACHMENT 3
RADIOLOGICAL SCANNING REPORT
DENISON
MINES
Dii
Mi Denison Mines Corp
6425 S. Highway 191, PO Box 809
Blanding, UT 84511
USA
Te): 435 678-2221
Fax : [phone]
www.deni3onmine3.com
DENISO
MINES
Memorandum
To: Jo Ann Tischler cc: Harold Roberts
Dan Hillsten
e r^ .4T ^ KathyWeinel From: David Turk Central Files
Date: April 26, 2012
Re: Radiological Survey of Clancone Area
The soil removal in and around the old Clancone Area has been completed. Soils were removed that contained
visual contamination and also anything that had gamma radiological measurements that exceeded twice
background.
The backgrourtd was determined from four locations to the west of the Claricone/Robert's Pond area.
Background #1 was collected at approximately 100 feet north of MW27 and the reading was 18 nR/hr.
Background #2 was collected approximately 1/10 of a mile west of fwlW27 and the reading was 16 ptR/hr.
Background #3 was collected at approximately 100 feet west of MW27 and the reading was 18 ^R/hr.
Background #4 was collected at approximately 25 feet north of WW3 and the reading was 20 nR/hr. The
average background reading was determined to be 18 |iR/hr.
A grid system was created starting at the concrete walkway along Robert's Pond eastern embankment. The
grid was set at ten feet increments south and east from that point. The actual excavation area was
approximately 55 feet wide and 25 feet deep. Below are the readings gathered at the assigned locations'
A1 -90 B1 -130 01 -60 01 -50 El -60 Fl -70
A2-30 B2-30 C2-30 02-30 E2-30 F2 -30
A3-30 B3-35 03-30 D3-25 E3-50* F3 -60*
A4-30 B4-30 04-25 D4-80* E4-60* F4 -70*
A5-35 B5-20 05-20 D5-30 E5-50* F5 -110*
A6-30 B6-25 C6-30 D6-30 E6-30 F6 -90*
The * indicates an area exceeding ttie twice background measurement. These areas had additional soil
removed {an additional 4 feet down). Below are those areas after the additional soil removal
04-30 E3-30 E4-25 E5-25 F3-30 F4 - 30
F5 - 35 F6 - 35
All readings listed are in nR/hr. The area has been released for back filling of the hole. A CD containing all
photos has been shipped to the Denver office for your use.