Overland Park company agrees to cut mercury emissions at Oregon plant

BAKER CITY, Ore. _ The largest source of mercury pollution in Oregon could be cut by more than half by 2011 under a deal with state regulators.

Ash Grove Cement near Baker City has reached a voluntary deal with regulators to cut its mercury emissions by 75 percent within 3 years.

The agreement with the Oregon Department of Environmental Quality requires the Overland Park-based company to install controls within two years for a cost estimated at $15 million to $20 million.

If the agreement is approved as expected, the company and regulators say the cement plant would be the first in the United States with a specific deal to cut emissions of mercury, a potent toxic substance that accumulates in fish and can cause nervous system disorders in humans.

Neither the U.S. Environmental Protection Agency nor Oregon law requires cement plants to reduce mercury emissions, but the EPA is being sued over the issue and eventually could issue limits.

Mark Riskedahl, director of the Northwest Environmental Defense Center, was part of an advisory committee that recommended the Ash Grove deal. Riskedahl's center frequently sues polluters who resist installing emissions controls.

"This process is so different," Riskedahl said Friday. "There's no regulation mandating it, and nobody threatened them with litigation. It was of their own accord."

He said Ash Grove would be the first cement plant to use a carbon injection control system to capture mercury.

Ash Grove has set a mercury reduction goal of 85 percent, with a fallback target of 75 percent. If its capture rate falls below 75 percent the company could face civil penalties unless it can show the technology cannot achieve the reduction and applies for a lower reduction standard.

Ash Grove mines limestone, slate and clay from a quarry near its plant at Durkee, southeast of Baker City. It bakes those ingredients and iron slag in a kiln at temperatures approaching 3,000 degrees, producing about 1 million tons of "clinker," a precursor to cement, each year. The process sends gas containing mercury up the kiln's 290-foot-tall main smokestack

Levels vary, but the limestone is unusually high in naturally occurring mercury, the company says, and the plant emits about 2,500 pounds of mercury a year.

The level puts Ash Grove among the top U.S. mercury polluters and more than 10 times the mercury emissions from Portland General Electric's coal-fired power plant in Boardman.

Last spring, Ash Grove brought in experts from the University of North Dakota's Energy and Environmental Research Center to try out an activated carbon control system.

The center injected particles of activated carbon into the emission stream. The mercury attached to the carbon, which was then captured in a series of filters.

The tests concluded that the technology, already used in coal power plants, would capture 65 percent to 90 percent of mercury emissions, depending on operating conditions.

Ash Grove has nine cement plants nationwide and prides itself on being an environmental leader. The company says it's the first U.S.-based cement producer to join a cement sustainability initiative launched by the World Business Council for Sustainable Development.


Information from: The Oregonian,