U.S. Water News
SALT LAKE CITY -- Toxic waste from hundreds of
abandoned mining operations across the West will not be
completely removed from streams until remediative attention
is given to colloids, microscopic particles that can carry
contamination downstream, a Utah scientist has determined.
Research by Briant Kimball, a geochemist at the U.S.
Geological Survey in Salt Lake City, also suggests that a
$13 million treatment facility at Leadville, Colo., has been
placed in the wrong location by the U.S. Environmental
Protection Agency (EPA).
Kimball's study, soon to be published in the journal Applied
Chemistry, has determined that despite reductions of up to
75 percent in toxic metals dissolved in river water, there
was only a 40 percent decrease in toxic metals that cling to
colloids. The Utah scientist claims that even after
treatment plants were constructed, colloids from the
Leadville cleanup facility carried toxic metals 140 miles
downstream. After settling in the river bed, the colloids
are flushed back into the river year after year in spring
runoff, Kimball said, providing a continuous source of
pollution. In turn, he pointed out, colloids are consumed by
insects and fish.
In response to Kimball's indirect claim that the Leadville
treatment plant is situated in the wrong place on a
tributary of the Arkansas River, EPA officials in Denver
counter that they had good reasons for requiring Asarco
Mining Co. to build the facility along the tributary stream
instead of in the river. EPA claims it plans additional
cleanup actions at Leadville within the next couple of years
to reduce the amount of latent pollution from the abandoned
mining operation.
Kimball sampled Arkansas River water and sediments during
1988-89, then again in 1992 after the treatment plant began
operation. He used ultrafine filters to collect colloids
from the river, then measured toxic chemicals attached to
the particles.
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