DRC-2014-001901 - 0901a0688040a020

Energy Fuels Resources (USA) Inc.
225 Union Blvd. Suite 600
Lakewood, CO, US, 80228
303 974 2140 ENERGY FUELS
www.energvfuels.com
DRC-2014-001901
February 21, 2014
Mr. Rusty Lundberg
Director
Division of Radiation Control
Utah Department of Environmental Quality
VIA EMAIL AND OVERNIGHT DELIVERY
195 North 1950 West
P.O. Box 144850
Salt Lake City, UT 84114-4820
Re: Modifications to Cell 2 Slimes Drain Piping, White Mesa Mill
Dear Mr. Lundberg:
This letter provides Energy Fuels Resources (USA) Inc's ("EFRI's") follow-up to our discussion
with Mr. Phil Goble of the Utah Division of Radiation Control's ("DRC") during a meeting on
November 12, 2013, regarding piping modifications to the Cell 2 slimes drain system at White
Mesa Mill (the Mill"). The modifications were in progress at the time of the November 2013
meeting and were completed on December 19, 2013. Neither the verbal update on November 12,
2013 nor this letter, were required by the Tailings Management System program applicable to Cell
2, or by the Mill's Radioactive Materials License or Groundwater Discharge Permit. This letter is
being provided to DRC for information purposes only.
Background
As discussed in EFRI's letter of January 28, 2013, which addressed effects of the abnormally extended
low temperatures of December 2012 and January 2013, the Mill identified that the Cell 2 slimes drain
transfer line underwent recurrent freezing. The transfer line "freezing" appears to be due to a
combination of low temperatures, and deposition of precipitates ("scaling") which resulted from the
supersaturated condition of the slimes drain solution, as discussed below.
The Cell 2 slimes drain solutions are transferred via a pump from the Cell 2 slimes drain sump
which discharges through a 4-inch high density polyethylene ("HDPE") pipeline to the northern
edge of Cell 4A. The pipeline extends more than 300 feet with very little grade. Specifically, the
line drops 10 inches in elevation over the dike from Cell 2 to Cell 3, and has no change in elevation
for the remainder of its length. Prior to December 19, 2012, the slimes drain pipeline was above
ground atop the dikes and/or sands of Cell 2 and Cell 3, discharging into Cell 4A near the dike of
Cell 4A.
N:\WMM\Cell 2\Cell 2 Slimes Drain\2 21 14 Ltr to R Lundberg Cell 2 Slimes Drain Upgrade.doc
Letter to R. Lundberg
February 21, 2014
Page 2 of 3
As discussed in the January 28, 2013 letter, during the initial December 2012 period of cold weather,
the Cell slimes drain transfer line to Cell 4A became frozen on December 17, 2012. Mill personnel
thawed the line with heating torches and returned it to service during December 18 and 19, 2012.
On December 19, 2012, Mill personnel buried the horizontal sections of pipe in 12 inches of borrow
soil atop Cell 3 to insulate the line against potential future freezing weather.
The Mill experienced another extended period of abnormally cold weather beginning on December
19, 2012. During the evening of December 19, 2012, the Cell 2 slimes drain transfer pipeline froze a
second time, even though it had been buried in 12 inches of soil. It remained frozen through January
3, 2013 despite additional efforts to thaw the line with heating torches during that period. EFRI
successfully thawed the discharge pipeline and returned the slimes drain pumping system to service
on January 7, 2013.
Mill personnel advised EFRI management that because the slimes drain line had frozen while it was
buried under a 12 inch insulating layer of cover soil, temperature was not the only factor
contributing to the line plugging problem. EFRI has concluded that scaling due to the super-
saturation (high dissolved and/or suspended solids concentration) of the slimes drain solution also
contributed to plugging of the line.
Cause of Line Plugging
The Cell 2 slimes drain transfer pump operates on a float system which turns the transfer pump on
when sufficient fluid has accumulated in the slimes drain collection area in the cell. As a result, the
pump and transfer line experience intermittent, not constant, flow. The pump operates at 20 gallons
per minute for the few hours per month it needs to pump the accumulated slimes. During most of
the year, and during typical winters, the intermittent flow is sufficient to prevent freezing of the 4-
inch transfer line. However, during the multiple cycles when the pump is off and the discharge line
is full but not flowing, the shallow overall grade prevents residual fluids from draining completely.
During these conditions, fluids remaining in the line have the opportunity to precipitate excess
solutes and/or suspended material, and produce scaling along the length of the pipeline.
Alternatives Evaluated
EFRI has evaluated two additional measures, in addition to the 12-inch soil cover insulation
discussed above, to prevent future freezing or plugging of the slimes drain discharge line.
1. A backup transfer procedure involving pumping the Cell 2 slimes drain fluids a shorter
distance to exposed tailings sands areas in Cell 3, could be used during severely cold weather
conditions. The shorter length of transfer line may permit easier thawing and maintenance of
slimes drain fluid flow. This option was identified in EFRI's letter of January 28, 2013.
2
Letter to R. Lundberg
February 21, 2014
Page 3 of 3
2. An additional volume of makeup water could be supplied to the slimes drain line to dissolve
the salts, minerals, or other solids that have contributed to scaling and plugging of the slimes
drain during periods of low or no flow.
Because Cell 3 is undergoing pre-closure steps and the Mill is actively reducing the remaining
liquid pool areas, EFRI has not chosen to transfer additional fluids from the Cell 2 slimes drain to
Cell 3 at this time. EFRI selected option 2, installation of a system to add makeup water to the
slimes drain line to dissolve the excess solids and keep the line flushed.
Modifications Installed
The Mill has installed a 2-inch water makeup line from groundwater chloroform pumping well
TW4-24, located at the southeast corner of Cell 1 which ties in to the Cell 2 slimes drain system.
The TW4-24 well pump operates on a delay device which turns the pump on once every two hours
for a period of twenty minutes. The TW4-24 2-inch HDPE PVC discharge line has been tied into
the Cell 2 slimes drain discharge line approximately 10 feet south of the slimes drain sump, near
the southern dike of Cell 2, and provides 18.1 gallons per minute of flow during the period that the
pump is on. This flow is frequent enough and of sufficient rate to flush and clear the slimes drain
line of scale-forming salts or solids. A check valve installed in the 2-inch makeup water line is
designed to prevent any potential backflow of fluids from the slimes drain line to the groundwater
pump discharge line. A plan view drawing of the TW4-24 transfer line and slimes drain transfer
line, and a labeled photograph showing pipeline connection details, are provided in the attachments
to this letter.
As mentioned earlier, the information above is not required by the Mill's Tailings Management
System program, but is being provided for information purposes. Please contact me if you have any
questions.
Yours very truly,
Energy Fuels Resources (USA) Inc.
Kathy Weinel
Quality Assurance Manager
cc: David C. Frydenlund
Philip Goble, Utah DRC
Dan Hillsten
Harold R. Roberts
Russ Topham, Utah DRC
David E. Turk
Attachments
3
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w:\usa\utah\mill\mapping\cell 2 slimes drain.dwg letter! rellis
Flow Meter
2 Slimes
I Drain Power Supply
Check Valve
Discharge Line Support
4" Discharge Line
r- 4" "Y" Connection
Cell 2 Slimes
Drain Access Pipe
Discharge Line
I Continues to Cell 4A
LDS
Erf
• Butterfly Valve
REVISIONS Check Valve Date By
Picture Taken Looking North Northwest sm4 t. ,«i u
2" Pipeline from TW4-24
Chloroform Pumping Well
Energy Fuels Resources (USA) Inc.
Project: White Mesa Mill
County: San Juan State: Utah
Location: Cell 2
Cell 2 Slimes Drain
Pipeline Connection Detail
RE •ate 1/27/14 | Drafted By:RE