COMMON
QUESTIONS &
ANSWERS
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Volume 5, Number 2 (October 2000)
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Q: |
Is the water level in the Pit
rising according to predictions? |
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A: |
No. The suspension of
mining in July 2000 has disrupted the predictions since more
water is entering the Berkeley Pit than was expected (see photos
at right). The extra water, about four to five million gallons
a day, is coming from the Horseshoe Bend flow, which had been
diverted away from the Berkeley Pit since April 1996. That diversion
project became part of mine operations. So, until Montana Resources
starts mining again, or figures out another way to divert and
treat the Horseshoe Bend flow, the water level in the Berkeley
will be rising twice as fast as expected.
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Q: |
Why is the water in the Pit
allowed to rise higher and higher? Why wait to build a treatment
plant? |
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A: |
Pitwatch readers have asked these questions
repeatedly. It's hard for residents to understand why something
isn't being done right away to deal with the toxic water in the
Pit. For the parties responsible for the problem and for any
adverse impacts from the water, the reasons for waiting are a
combination of science, time and money.
In general, the Berkeley Pit is considered a big holding tank,
with a well-defined capacity. Based on years of scientific study,
the EPA and MDEQ have determined that the water in the Pit does
not and will not pose a threat to human health or the environment
as long as the level stays below the 5,410-foot level. This conclusion
is part of the Record of Decision that dictates when and what
happens at the Pit. With the current level at 5,189, there is
about 220 feet of "storage space" left in the Pit.
As owners responsible for water treatment, Montana Resources
and ARCO are trying to use that "storage space" in
the most effective way.
For starters, any delay reduces costs to operate and maintain
a treatment facility. Annual costs are expected to exceed $3
million, so for as long as possible, it is considerably cheaper
to manage the Pit as storage space. Also, some scientists believe
that letting the water rise to maximum safe levels will eventually
lower the water's acid and metals content by reducing the amount
of sulfur-bearing rock that's exposed to air. That may improve
water quality and make it cheaper to treat the water when the
time comes.
In addition, the delay allows time for new treatment technologies
to be perfected. If water treatment were to begin today, the
most cost-effective, reliable technology would be lime precipitation,
which is essentially mixing the toxic water with lime. But this
process would produce massive amounts of toxic sludge, which
creates another waste disposal problem in Butte. On the other
hand, with the benefit of time, the hope is that innovative,
cost-effective technologies will emerge to recover valuable metals
in the water, or at the very least, reduce the amount of toxic
sludge produced.
For now, the emphasis is to monitor the water carefully. As storage
space in the Pit begins to run out, safeguards are in place to
make sure a treatment plant will be ready. As shown on the timeline
(see bottom of pages 2&3), design work must begin eight years
before the water in any of the wells or shafts is expected to
reach the 5,410' elevation and the treatment plant must be ready
to operate four years ahead of time. This timeline is reviewed
and evaluated by the Agencies every year and updated as needed.
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