DRC-2012-001368 - 0901a068802c997d

State of Utah
GARY R. HERBERT
Govemor
GREG BELL
Lieutenant Govemor
Department of
Environmerital Quality
Amanda Smith
Executive Director
DIVISION OF RADIATION CONTROL
Rusty Lundberg
Director
TO:
FROM:
DATE:
SUBJECT:
MEMORANDUM
Phil Goble, Section Manager '
Russell J. Topham, P.E.
April 18,2012 r
Observation of conditions following sulfuric acid spill, Denison Mines (USA) Corp.
(DUSA) White Mesa Mill, Blanding, Utah, April 14, 2012.
On April 12, 2012,1 traveled to the DUSA White Mesa mill on behalf of the DRC. While there, I observed
conditions surrounding a sulfuric acid release at the Claricone component ofthe leachate clarification
system.
The Claricone is an upflow sludge blanket clarifier used in various water treatment and chemical processes
to remove precipitated solids from the fluid stream. Fluids enter the Claricone at its base, which in this case
was buried several feet in the ground. Piping introduces the fluid tangential to the cone circumference.
Fluid then travels up the inverted conical shape of the unit, in constantly widening spirals. Near the top of
the cone, the upward component of velocity of the fluid matches the downward velocity of settling
precipitates. Clarified fluid passes over the launder and is directed one way, while solids collect in the
cone, concentrate into a dense sludge blanket, and are drawn off for further treatment.
The influent pipe transporting leachate to the Claricone failed, releasing a large quantity of leachate
solution to the ground at the base of the Claricone. A service tunnel was flooded, and soil at the base of the
Claricone subsided, nearly filling the tunnel with mud. Most of the leachate was recovered and pumped to
Roberts Pond pending final disposal. Some fluid was collected on the ground surface, where most of that
fraction followed a drainage waterway to Roberts Pond. Sulfuric acid content of the release was estimated
to exceed 1000 lbs, and was reportable under RCRA. Calculations were proceeding while I was onsite to
determine the quantity of uranium released in the event.
In the case of uranium processing, several plants built roughly concurrently with the White Mesa mill
incorporated the Claricone in their process trains. Prior to being mothballed or decommissioned, the other
plants had eliminated the Claricone from the process train, inasmuch as the acidic nature of the leachate
prevented precipitation of solids ahead of the Claricone. DUSA plans to bypass and decommission the
Claricone.
DUSA commenced removal of contaminated soil prior to my leaving the site on April 13, 2012. Soils were
being placed in Cell 4A.
168 North 1950 West • Salt Lake City, UT
Mailing Address: P.O. Box 144850 • Salt Lake City, UT 84114-4850
Telephone [phone] • Fax (801) 533^097 • T.D.D. [phone]
www.deq. utah.gov
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