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Errors understate mercury emissions
Pollution
- A faulty formula the
MICHAEL
MILSTEIN
An
The new figures released
Thursday make the Ash Grove Cement plant in Durkee
the third largest source of airborne mercury in the nation in 2004, the last
year with national statistics available. The only larger sources were a
Coal-fired plants are the
nationwide target of new regulations to control mercury, which collects in the
food chain and puts babies at risk of neurological damage and learning
disabilities.
But the Durkee plant in 2004 vented into the air more than a ton of
mercury, hundreds of pounds more than the nation's largest coal-burning power
plant, according to federal figures.
No mercury limits apply to
cement plants because the U.S. Environmental Protection Agency has concluded no
reasonably priced controls are available.
The Durkee
plant's new figures surprised air-quality officials. They said it suggests
cement kilns -- where mercury emerges from limestone heated to make cement --
are a much larger source of the toxic compound than anyone had recognized.
"We're seeing a
pervasive underreporting throughout the country of mercury from cement kilns,"
said Bill Becker, director of a nationwide alliance of state
and local air-quality regulators.
The Oregon Department of
Environmental Quality re-examined the Durkee cement
plant's releases after a June article in The Oregonian identified it as a much larger
source of mercury than Oregon's only coal-fired power plant.
DEQ officials found that Ash
Grove used incorrect figures when calculating the mercury released by its
plant. The actual amount is roughly two to three times higher, depending on the
year.
That puts its recent
emissions at about 10 times those of Portland General Electric's coal-fired
power plant near Boardman, the subject of a new state mercury-control rule.
Within the next month, DEQ
officials will order Ash Grove to conduct more intensive tests of its
emissions, said Andrew Ginsburg, administrator of DEQ's
air-quality division. The DEQ then will consider whether mercury controls are warranted
and would be cost effective.
Origin of errors
The discrepancy in the
plant's reported mercury releases arose because a Seattle company that
performed testing at the plant in 2001 gave Ash Grove incorrect figures. DEQ
officials caught the problem at the time, and the
But the testing company
never sent the new figures to Ash Grove.
So Ash Grove used the
earlier incorrect figures to calculate the plant's emissions and submit them to
a federal database available to the public.
That is not a violation
because the company used the best information it had available at the time,
said Christina Colt of the U.S. Environmental Protection Agency regional office
in
Federal laws do not require
Ash Grove to correct the faulty numbers. But company officials said they opted
to do so because of the national interest in mercury emissions.
Trace amounts of mercury in
limestone quarried at the Durkee plant are
responsible for almost 99 percent of the mercury released, Ash Grove said. The
rest comes from coal burned to heat the cement kiln.
Limited testing
The company said its
calculations of mercury emissions are based on limited testing from five years
ago, rather than continued monitoring of what comes from the roughly
25-year-old plant.
Mercury in the air typically
does not pose a risk to people who breathe it. It poses the widest risk when it
washes into rivers and streams, and collects in fish in a more highly toxic
form.
Most people are exposed to
mercury by eating contaminated fish. At least one in 12 babies -- and possibly
more -- born in the
Studies suggest that much of
the mercury from cement kilns emerge as vapor that drifts far away, said Bruce
Hope, a DEQ environmental toxicologist. However, it's impossible to say clearly
how much risk the cement plant's emissions pose to residents in Durkee or
That depends on local
circumstances such as the operation of the plant, the forms of mercury emitted,
weather patterns and other factors.
"Not all mercury is
created equal," he said. "In theory you could live next door to a
smokestack and be fine, and live 10 miles away and not be fine. It just depends
on the situation."
Greater DEQ focus
But he said the DEQ now is
focusing much greater attention on the cement plant to better gauge the human
risk.
A coalition of environmental
groups said the DEQ should immediately begin testing local children and other
residents for mercury exposure, and start checking mercury levels in nearby
soils, streams and air. The testing is part of DEQ's
legal obligations, said the groups: Columbia Riverkeeper,
The EPA also is considering
new national rules to control mercury from cement plants and last month sought
more details on their emissions, said John Millett, a
spokesman. He said the EPA will work with states to consider details such as
the Durkee plant's releases.
Michael Milstein:
503-294-7689; michaelmilstein@news.oregonian.com