MAC: Mines and Communities

Errors understate mercury emissions

Published by MAC on 2006-08-04

Errors understate mercury emissions

A faulty formula: the Eastern Oregon kiln used for tests leads the DEQ to talk of possible limits on the output

Michale Milstein, The Oregonian

4th August 2006

An Eastern Oregon cement plant that releases more toxic mercury into the air than any other source in the state actually emits far more mercury than it had reported to authorities.

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 California cement plant and a Nevada gold mine.

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 Seattle company -- Valid Results Inc. -- sent a corrected report to DEQ.

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 Seattle.

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 United States is at risk of developmental disorders because of mercury exposure, research shows.

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 Eastern Oregon, he said. It depends on 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, Northwest Environmental Defense Center and the Oregon Public Interest Research Group.

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;

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