DRC-2010-004823 - 0901a068801bee03

DRC-2010-004823
DENISO
MINES
August 30, 2010
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 84114-4820
Denison Mines (USA) Corp.
1050 17th street. Suite 950
Denver, CO 80265
USA
Tel: [phone]
Fax:[phone]
www.denisonmines.com
VcA Radiation
Control
Re: State of Utah Ground Water Discharge Permit ("GWDP") No. UGW370004 White Mesa Uranium
Mill - Plan and Schedule for Cell 1 Inspection and Repairs, Update
Reference is made to Denison Mines (USA) Corp's ("Denison's") notice letter of June 7, 2010 and telephone
conferences with Utah Department of Environmental Quality ("UDEQ") on August 12, and August 23, 2010.
Denison's June 7, 2010 letter provided a notice to the Executive secretary regarding liner repair work needed to
address the discovery of fluid level in the Leak Detection System ("LDS") of the White Mesa Mill's (the "Mill's")
Cell 1. In response to a phone conference on August 12, 2010, Denison provided a status update letter to
UDEQ on August 18, 2010 containing a proposed plan and schedule for inspection and repairs to Cell 1.
UDEQ and Denison reviewed the proposed plan during a conference call on August 23, 2010. This letter
responds to UDEQ's request during the August 23 conference call that Denison provide a written submittal that:
• includes an update of the estimated fluid inflow rate during the August LDS monitoring, and
• modifies and clarifies the repair schedule.
Current Status
Since the time of the August 7 detection of fluid in the LDS, the Mill has continued to:
• circulate and transfer fluids to reduce the solution level in Cell 1,
• pump and monitor the observable LDS liquid level, and
• estimate the rate of inflow of fluids into the Cell 1 LDS from the pumped LDS fluid volumes.
Preliminary analytical data received to date has confirmed Denison's assumption that the observed fluid in the
LDS consists of Cell 1 solutions.
The Cell 1 LDS system was determined to be dry, that is, no fluid was observable in the standpipe, on August
18, 2010 and remains dry at the time of this writing. Denison has concluded that at the current liquid pool level
of 5613 feet amsl, the liquid level is lower than any tears or damaged areas in the liner that produced the
observable LDS liquid level in August 7, 2010.
Letter to Rusty Lundberg on Cell 1 Repair Schedule
August 30, 2010
Page 2
As requested by UDEQ, Denison has provided in Table 1, below, estimates of inflow of solution into the Cell 1
LDS from the time of the LDS liquid detection on August 7, 2010 until the LDS system became dry on August
18, 2010, stated in gallons per minute ("gpm").
Update to Repair Schedule
Cell 1 has a perimeter above the 5613 foot amsl level of approximately 6,500 linear feet, of which approximately
6,000 feet have not been recently inspected and/or repaired. A full inspection and repair of all areas of the liner
surface above the 5613 foot level would require the systematic removal of the protective soil cover, inspection
of the exposed, uncovered flexible membrane liner ("FML") material, and repair of any identified damaged areas
at or above this level. Denison has explained in our plan letter of August 18, 2010 and phone conversation of
August 23, 2010, that Denison does not wish to expose significant areas of the FML at any one time or to
disturb any more of the FML than is necessary, but plans to inspect and repair the FML in sections in a
stepwise fashion to minimize the risk of creating any new damage. Further, Denison plans to uncover and
inspect first the areas of the FML that are most likely to exhibit tears or damage, such as areas near or affected
by discharge piping vibration or other stress factors. Denison plans to raise the solution level in Cell 1 above
5613 fmsl periodically in order to test the success of certain steps in the repair process.
Denison has provided, in Table 2, below, an updated estimate ofthe time required to perform repairs to the Cell
1 liner as described in the August 18, 2010 update letter and discussed in the August 23 phone conference with
UDEQ.
Denison has already mobilized, from among available personnel, one four-man crew including one supervisor,
and has repaired 200 linear feet of liner surface since June 2010.
Denison will need to expand the liner maintenance force to three (3) three-man crews. Although this process is
underway, development of a full complement of repair personnel will require a minimum of several weeks due to
the time needed to identify, recruit, and train qualified personnel. Denison does not plan to expand the repair
team to include larger crews because the maintenance of safe working conditions is of paramount priority.
Specifically, the ability of supervisors to enforce adherence to safety requirements is most effective at smaller
crew sizes. Denison does not plan to expand the number of repair crews (that is, total repair personnel beyond
three crews) due to practical aspects of personnel retention. It is Denison's intention to be able to utilize each
cprew member for other operational tasks throughout the Mill during periods when weather conditions preclude
liner repair work. Having sufficient alternate work activity for crew members during down periods is critical for
minimizing attrition and maintaining a sufficient number of qualified, trained personnel on hand during repair
periods.
Three (3), three-man crews can theoretically uncover, inspect, and repair the FML at a peak rate of
approximately 160 linear feet per week, or 640 linear feet per month, under optimum conditions. The theoretical
peak productivity is tabulated in the column in Table 2 labeled "Maximum Feet Repaired under Optimum
Conditions." The theoretical peak productivity would require:
• a full complement of trained staff available every day of the month with no attrition,
• safe access conditions suitable for liner repair every day of the month (no snow cover, no muddy or
slippery footing), and
weather conditions suitable for liner repair work every day of the month (above 50°F, no high winds,
no snow or rain).
DENISO
MINES
Letter to Rusty Lundberg on Cell 1 Repair Schedule
August 30, 2010
Page 3
Several factors need to be considered to adjust the theoretical peak productivity to real productivity for the
purposes of this schedule.
Pre-training. Denison requires all repair crew members to be appropriately trained in the technical and health
and safety aspects of the liner repair task before being assigned to a crew.
Safe and effective access. Denison will not require crews to access the FML under slippery, muddy
conditions, high winds, or other weather conditions that create hazardous footing. The FML soil cover cannot
be effectively removed or the FML inspected under snow cover.
Other weather factors. The ability to manipulate and repair damaged sections of the FML and the effectiveness
of the repair sealants depend on moderate temperatures, generally above 50°F.
Denison has incorporated key assumptions to address the factors above and adjust the theoretical peak
productivity to a more realistic monthly productivity in Table 2. The realistic monthly and total productivity is
listed in the column labeled "Actual Feet Repaired Based on Assumed Conditions." The value in the "Actual
Feet Repaired" column is based on the following assumptions:
1. Sufficient numbers of trained personnel are not in place at the time of this writing. Recruiting and
training to reach a full complement of three (3) three-man crews is underway. Hence, the maximum
feet repaired will increase from the first to second month (September to October) of the repair schedule
as the full complement of repair personnel are recruited or transferred and trained. However, the
indicated linear footage to be repaired by the end of September 2010 is higher than the 200 linear feet
proposed in our plan letter of August 23, 2010.
2. No repairs will be performed during the months of November through March of each working year due
to snow or muddy conditions, temperatures too low for proper setting of repair materials, or both.
3. The percentage of working days available in the remaining months (April through October) in Table 2
have been adjusted based on typical weather conditions anticipated in each of those months.
As mentioned above the projected linear feet per month, and total months to address the entire perimeter of
Cell 1 are based on these specific assumptions. If weather conditions vary from the assumed conditions,
productivity may be higher or lower than tabulated, which would affect the schedule set out in Table 2. Also, if
repairs are determined to be successful at any point in time, based on no inflow of fluids into the Cell 1 LDS
after raising the solution level in Cell 1, then Denison may discontinue any further repair work at that time.
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
DENISO
MINES
Letter to Rusty Lundberg on Cell 1 Repair Schedule
August 30, 2010
Page 4
cc: Rich Bartlett
David C, Frydeniund
Ron F. Hochstein
Harold R. Roberts
David E. Turk
Kathy Weinel
DENISO
MINES
Letter to Rusty Lundberg on Cell 1 Repair Schedule
August 30, 2010
Page 5
TABLE 1
Estimation of Cell 1 Leakage Rate from August Fluid Detection
Until Leak Detection System Dryness
Date Time Conditions at Time of
Level Measurement
Approximate Depth
to Liquid Level
Calculated
Leakage rate
8/7/2010 21:30 During routine inspection 61 feet 8 inches
8/8/2010 13:55 Before pumping
standpipe
60 feet 8 inches 0.01
8/9/2010 09:00 Before pumping
standpipe
60 feet 2 inches (dry) 0.02
8/10/2010 14:24 Before pumping
standpipe
Unable to read 0.02
8/11/2010 13:15 Before pumping
standpipe
63 feet 9 inches (dry) 0.01
8/12/2010 15:00 Before pumping
standpipe
64 Feet 2 inches 0.02
8/13/2010 10:40 Before pumping
standpipe
65 feet 0 inches (dry) 0.02
8/14//2010 14:20 Before pumping
standpipe
66 feet 2 inches 0.01
8/15//2010 16:15 Before pumping
standpipe
66 feet 4 inches (dry) 0.01
8/16//2010 14:50 Before pumping
standpipe
67 feet 5 inches 0.01
8/17//2010 13:45 Before pumping
standpipe
68 feet 5 inches 0.002
8/18/2010 14:30 Before pumping
standpipe
No liquid present 0
8/19/2010 14:45 Before pumping
standpipe
No liquid present 0
DENISO
MINES
Letter to Rusty Lundberg on Cell 1 Repair Schedule
August 30, 2010
Page 6
TABLE 2
Estimated Liner Repair Rate Based on Assumed Weather Conditions'
Year Month Maximum Feet Percent Working Actual Feet
Repaired under Days Based on Repaired Based on
Optimum Anticipated Assumed
Conditions Weather Conditions
2010 September 400 80% 320
October 640 70% 448
November 640 0% 0
December 640 0% 0
2011 January 640 0% 0
February 640 0% 0
March 640 0% 0
April 640 50% 320
May 640 70% 448
June 640 90% 576
July 640 90% 576
August 640 80% 512
September 640 80% 512
October 640 70% 448
November 640 0% 0
December 640 0% 0
2012 January 640 0% 0
February 640 0% 0
March 640 0% 0
April 640 50% 320
May 640 70% 448
June 640 90% 576
July 640 90% 576
Totals 6,080
' Assumes typical weather conditions at Mill site. Productivity rate may be higher or lower if weather permits more or
fewer days of safe access.
DENISO
MINES