COMMON
QUESTIONS &
ANSWERS
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Volume 2, Number 1 (April 1997)
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Q: |
Are the water levels in the
Pit and the monitoring sites rising as expected? |
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A: |
Yes. Even with heavy snowfall
this winter, the Pit's level continued to rise as expected. In
general, nothing out of the ordinary is happening. The water
levels in the monitoring wells are also rising as predicted and
continue to be 10 to 20 feet higher than the Pit's water level.
These higher measurements indicate that the surrounding ground
water is still flowing inward, toward the Pit, much like runoff
flows down into storm drains.
In our monthly column in August 1996, we mentioned that the water
levels at Monitoring Site DDH-5 east of the Pit were rising and
falling, rather than steadily rising. From September on, however,
the water has risen steadily at least one foot per month. We
checked into the erratic readings and found out that the problem
was unrelated to the water in the well. As it turns out, the
monitoring equipment was accidentally bumped which led to the
incorrect summer measurements. In September, the well casing
was removed and then replaced.
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Q: |
Is the Horseshoe Bend diversion
project working as planned? |
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A: |
Yes. Since the diversion
project went on-line last April, only about half as much water
is entering the Pit - about 3 million gallons per day instead
of 6 million. This means that the water level now rises about
one foot per month instead of two feet. The diversion project
is part of the cleanup efforts ordered in the September 1994
Record of Decision (ROD) by the U.S. EPA and the Montana Department
of Environmental Quality (MDEQ).
The cost of this water diversion and treatment project included
about $400,000 in start-up costs and now $1-$2 million in annual
operating expenses. These costs are shared by ARCO and Montana
Resources.
Here's how the diversion project works: The stream of water that
used to flow into the Pit's northeast side is now pumped uphill
to the Yankee Doodle tailings pond. Before its release into the
pond, the highly acidic water is mixed with a combination of
lime and tailings that is pumped up from the Montana Resources'
concentrator. This mixing process draws some of the metals away
from the water and reduces its acid content, leaving it clean
enough to be reused. Each day, about 22 million gallons of water
from the tailings pond are piped down to the concentrator for
reuse. This amount of water includes not only Horseshoe Bend
flow, but also water that separates out from the Continental
Pit tailings.
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Q: |
How long will it be before
the water in the Berkeley Pit is treated? |
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A: |
With the Horseshoe Bend
project now in place, water treatment has begun. As for the water
in the Berkeley Pit, treatment will begin as soon as the water
level in the Pit or in any of the surrounding monitoring wells
reaches 5,410 feet—the level determined to be the "critical
water level" by EPA and MDEQ. That level is expected to
be reached around 2021. To ensure that Pit water treatment starts
when it's needed to protect human health and the environment,
the plant will be ready to go four years beforehand.
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