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U.S. Fate of MOAB uranium mill tailings pile still undetermined

Nuclear Monitor Issue: 

(June 28, 2002) The U.S. National Academy of Sciences has called for more study before a decision is made on the management option to be pursued for the Atlas Moab uranium mill tailings, which continue to leak into the Colorado River - the main source of drinking water for 25 million Americans.

(570.5419) WISE Uranium - The 10.9 million t uranium mill tailings pile located near Moab, Utah (t = metric ton in this article). The Academy in particular draws attention to the long-term hazards such as anticipated migration of the bed of the Colorado River towards the pile, and the appropriate consideration of continued long-term management cost vs. actual reclamation cost.


Uranium mill tailings are what is left over from the extraction of uranium from uranium ore. They contain most of the volume and 85% of the initial radioactivity of the ore. They are normally dumped as a sludge in special ponds or piles, where they are often abandoned, forming a radioactive and chemically toxic hazard. The hazard can be reduced by reclamation, which is intended to confine the radioactive and toxic contaminants in a safe and maintenance-free condition, for example by dewatering the tailings and covering them with layers of protective materials. WISE Uranium web site

The 52.6-hectare pile is located 230 meters from the bank of the Colorado River and is a source of continuous toxic seepage into groundwater and into the river. The Colorado River is the main source of drinking water for about 25 million downstream residents in Arizona and California. The tailings are the byproduct of processing uranium ores from many small mines in the area in the Moab uranium mill between 1956 and 1984, when the mill was shut down by its then owner Atlas Corp.

Atlas Corp's reclamation plan provided for capping the pile in place at an estimated cost of US$13 - 16 million. The government was set to reimburse 56% of this cost, that is the fraction related to the processing of uranium produced for the nuclear weapons program. So, Atlas Corp., in agreement with the regulating authority NRC, set aside US$6.5 million in the form of a surety bond to cover the remaining part of the reclamation cost.

So far, the story went on as usual, but then a few things happened leading to the current situation that the fate of the pile is still unclear 18 years after it ceased operation. Other federal agencies, such as the Environmental Protection Agency (EPA) and the Fish and Wildlife Service (FWS), along with environmental organizations such as the Grand Canyon Trust, opposed the reclamation of the tailings in place and called for their relocation to a more suitable site. These opinions were assimilated by the downstream states concerned for their drinking water. One big question was, however, who would pay for the much higher cost of relocation compared to the capping in place. Meanwhile, however, even the estimates for the reclamation in place had risen and Atlas Corp declared bankrupt since it was not able to provide additional money. Subsequently, NRC named a trustee, Pricewaterhouse Coopers, to perform the reclamation in place.

In January 2000, the Department of Energy (DOE) came up with a plan for the relocation of the pile. DOE has successfully relocated a number of, though smaller, uranium mill tailings piles in the past. Two preconditions had to be met to make this plan a viable option: the title for the pile (still with NRC) had to be transferred to the DOE, and money had to be provided for the estimated relocation cost of $300 million. In October 2000, Congress enacted a bill, providing for those preconditions - at least as it seemed at that time. Subsequently, ownership for the site was indeed transferred to the DOE, but, newly elected President Bush allocated no funds for the relocation.

In October 2001, the DOE presented a Draft Preliminary Plan for Remediation, analyzing the options of reclamation in place and of relocation in more detail. The cost estimates dramatically rose to US$114 million and US$364 million, respectively. As ordered by Congress, this Draft Plan was submitted to the National Academy for review.

In the meantime, several companies made proposals for differing relocation options at lower cost: Plateau Resources, a subsidiary of U.S. Energy Corp., proposed to relocate the tailings to its Shootaring Canyon mill site, International Uranium Corp. (IUC) proposed a slurry pipeline for the tailings' relocation to its White Mesa Mill site near Blanding, and Summo Minerals proposed to truck the tailings to its Lisbon Valley site. Also in the meantime, the trustee continued its work for the reclamation in place.

In order to place the final cover on top of the tailings pile, the tailings first need to be dewatered. Otherwise, the tailings mass would consolidate under the cover mass and the cover would crack shortly after installation. The dewatering was to be achieved by wick drains installed from the surface of the pile. The wicks are combined with an intermediate preload cover, the weight of which would help to "squeeze" the liquid out of the tailings.

Approx. 360,000 meters of vertical wick drains were installed in 2000 to accelerate tailings consolidation and provide hydraulic relief prior to placing the final cover. The dewatering, however, turned out to be less effective than anticipated since not enough funds had been available to cover the tailings with the necessary preload for the wicks to become most effective.

While this dewatering effort makes sense for most of the management options considered, it would become obsolete, if IUC's slurry pipeline relocation proposal would be selected: in this case, the tailings would again have to be mixed with water to form a slurry that can be pumped through the proposed pipeline.

What can we learn from the Atlas Moab case?
Most impressive is the rise in the cost estimates for the reclamation of the tailings pile (see Table 1).

Table 1. Estimated Reclamation Cost (US$million)
  On-site Cap Relocate
1979 (Atlas) 3.3  
1996 (Atlas) 13 - 16  
1998 (Atlas) 22  
2001 (DOE) 114 364

Only the 1996 estimate was covered by Atlas' surety bond. Due to the gross increase of even the in-place reclamation cost estimates (not to speak about the relocation alternative costs), the surety bond became rather useless. That is, the taxpayer will have to pay for the reclamation, while the company that caused the mess simply went bankrupt. So, one question is: why did the NRC approve this grossly underrated reclamation cost estimate?

To put these numbers into perspective, Table 2 compares the specific reclamation cost per tonne tailings and per pound U3O8 produced to those incurred at other tailings sites. (1 pound (lb) = 454 g)

Table 2. Specific Reclamation Cost per t tailings and per lb U3O8 produced

- Moab estimates -

historic average
  NRC DOE DOE Title I Title II
  Cap Cap Relocate    
$/t tailings 1.4 10.5 33.3 68.37 1.51
$/lb U3O8 0.4 3 9.7 14.70 0.44
(based on costs of 15 / 114 / 364 $million, estimated uranium production of 14,400 t U, and 10.9 million t tailings)

Title II: sites where the current owner performs the reclamation, supported by partial government reimbursement for tailings resulting from production of uranium for nuclear weapons
Title I: designated old sites, reclamation exclusively performed by DOE

NRC's original cost estimate for the cap in-place option thus was well within the average cost observed so far for Title II sites. DOE's new estimates come closer to the average cost for Title I sites, though even the relocation cost remains below half of the Title I cost.
By coincidence, DOE's estimate for the relocation cost, expressed as $ per pound U3O8 produced at the Moab mill, is nearly identical to the current uranium spot market price of US$9.90. In other words: the cleanup would consume the complete sales price of the uranium produced, if sold at current spot prices.

The observation that NRC's original cost estimate met the average Title II cost, raises the question what the situation at those sites will be? Are there future disasters looming?

In fact, for most of the major Title II sites, their respective owners have requested so-called "Alternate Concentration Limits" (ACL) for contaminants in groundwater. That is, the owners request relaxed groundwater standards since they are not able (and/or willing?) to meet NRC's groundwater standards. Those requests most often do not ask for relaxation of certain parameters by some percentage, but by factors such as 100 or 1000. NRC already has approved many such requests and is to approve the remaining ones shortly.

For details, see also the Moab page on WISE Uranium Project's web site:

Source and Contact: WISE Uranium