Re: Scare tactics

[7pe@ornl.gov (Phil V. Egidi)]

My experience with uranium mills and mill tailings is that there often is
residual uranium in the tailings left over from processing that was not
recovered.  The mills had varying recovery rates depending on the
composition of the ore and the process used.  Usually, if you cleaned up
the radium, you got the uranium and thorium also.  But Uranium 234 and
U-238 are more soluble and mobile than Ra-226 or Th-230 (which is also in
the tailings), and often show up in the ground water in elevated
concentrations.  

Another consideration is that "other stuff" is usually found buried on
these sites or in the piles, such as lab vials, resin beads, buried piping
and equipment, all of which can contribute to a uranium source term if in
contact with groundwater.

One old site I am familiar with used an acid leach process, and when
characterized shows very little radium in the groundwater, but has a
uranium plume well above State limits.  The elevated levels generally
disappear(is dilution the solution?) when they hit the river (most mills
are by a river). We also found at this site that Th-230 leached from the
tailings into the soil approx. 2 ft deeper than the radium did, which made
it the driver under DOE Order 5400.5.  This increased sampling and
remediation costs.  

There are often plumes of moly, lead, arsenic, vanadium, and other metals
associated with the ore in the groundwater.  Radium-226 is the driver for
UMTRA (40CFR192) basically because of the radon hazard, the other metals in
the tailings are exempt from regulatory control under UMTRA.  The recent
(1995) amendment to 40CFR192 addresses contamination in groundwater from
uranium mills, and is similar to 10CFR40(?)App.A. (metals are regulated in
the groundwater). 

I find it disturbing that the contamination from a mill hundreds of miles
away is being used as a scare tactic.  The amonium is measureable in the
Colorado River at Moab (even after dilution), it is a real problem locally
to aquatic species. Locally.  The discussion of dilution being a solution
to pollution is beyond the scope of this post! 


Phil Egidi
ORNL/GJ
7pe@ornl.gov




At 10:56 PM 2/9/99 -0600, you wrote:
>In a message dated 2/9/1999 6:12:34 PM Pacific Standard Time,
>aduchem@wantree.com.au writes:
>
><< Absolutely 100% right. But there is enormous difficulty in convincing
> people that the tailings problem is NOT uranium. Certainly if U is detected
> in the drinkign water it must have come from another source, and not the
> tailings. >>
>
>You may be right, but I am not so sure.  What extraction mechanism is 100%
>effective in removing all the uranium?  I would think that there would be
some
>uranium in the tailings as well as the other members of the decay chain.  T
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