Wilmington (Del.) News Journal  [Printer-friendly version]
August 27, 2007


States search for ways to get rid of coal ash with toxic chemicals

By staff and wire reporters

OMAHA, Neb. -- As the nation's coal-fired power plants work to create
cleaner skies, they'll likely fill up landfills with millions more
tons of potentially harmful ash.

More than one-third of the ash generated at the country's hundreds of
coal-fired plants is now recycled -- mixed with cement to build
highways or used to stabilize embankments, among other things.

But in a process being used increasingly across the nation, chemicals
are injected into plants' emissions to capture airborne pollutants.

That, in turn, changes the composition of the ash and cuts its
usefulness. It can't be used in cement, for example, because the
interaction of the chemicals may keep the concrete from hardening.

That ash has to go somewhere -- so it usually ends up in landfills,
along with the rest of the unusable waste.

"You're replacing an air problem with a land problem -- a disposal
problem," said Bruce Dockter, a research engineer with the Energy and
Environmental Research Center at the University of North Dakota.

Coal ash naturally contains arsenic and mercury, and if the elements
leach into groundwater they can contaminate drinking supplies. The EPA
says ash disposed of in landfills could pose significant risks when
mismanaged, and there are gaps in state regulation.

And the chemicals added to clean up emissions -- such as ammonia, lime
and calcium hydroxide -- make the ash worse, environmental groups say,
because they take toxins such as mercury out of the air but leave
higher levels of it in the ash.

Problems at Indian River power plant

To keep a 20-year-old heap of potentially polluted power plant ash
from sliding into the water in Delaware, the owner of the Indian River
power plant has proposed stabilizing nearly two miles of the river's

NRG Energy Inc., which bought the plant and the ash pile from Delmarva
Power in 2001, has proposed the work for the eastern side of Burton

In 2006, Department of Natural Resources and Environmental Control
officials notified the companies of potential cleanup problems with
the waterfront landfill, which was used between 1957 and the late

A document filed with the Department of Natural Resources and
Environmental Control calls for extensive work to stop further erosion
at the site, including the installation of a 9,803-foot wall made of

A stone "sill," or lip, will be built along another 382 feet of marsh
shoreline, while 225 feet will be protected with coconut-fiber logs.

The plant's owners closed and covered the ash pile based on standards
used in the late 1970s, NRG reported. But waves along Indian River and
a tributary called Island Creek ate away at protective bulkheads and
shorelines, exposing the ash to the river.

EPA: Not hazardous waste

The U.S. Environmental Protection Agency doesn't classify coal ash --
with or without the added chemicals -- as a hazardous waste, although
many environmental groups say it should.

"As a general rule, anything you do to make the air emissions cleaner
makes the ash more toxic," said Lisa Evans, an attorney with
Earthjustice, a nonprofit environmental law firm.

More than 120 million tons of ash and other leftovers come from coal
combustion each year in the United States, and more than 46 million
tons are reused, according to the American Coal Ash Association.

Environmental groups encourage reuse of the ash because it keeps most
of the waste out of landfills. And substituting ash for cement means
less mining for the materials typically used to make cement --
consequently causing a drop in the amount of carbon dioxide that would
be emitted by mining machinery.

But the EPA is pushing power companies to cut emissions of the sulfur
dioxide and nitrogen oxides, which add to smog and acid rain and
contribute to thousands of premature deaths, asthma and other
respiratory ailments. A large portion of those emissions come from
coal plants, the EPA says.

"If you live near a power plant, you want the cleanest air possible,"
said Dave Goss, executive director of the American Coal Ash
Association. "If in exchange for clean air they have to dispose of
material -- that's the challenge. The only option may be putting it in
a landfill."

The issue was raised as the EPA developed air emissions rules, but the
power sector has found ways to minimize the impact, said EPA spokesman
John Millett, who said the agency doesn't believe the increased
injection of the chemicals into ash will cause a significant drop-off
in ash recycling.

It's not clear how many plants already are using or will use the new
technology or how much ash may be affected, but the technique is
becoming widespread as companies work to comply with federal
guidelines, Goss said.

This month, the Maryland Department of the Environment ordered the
operator of an 80-acre Anne Arundel County coal ash dump to clean
contaminated water detected near the site. Cancer-causing metals were
discovered last fall in almost two dozen wells in the area. BBSS Inc.
also was fined an undisclosed amount.


Coal combustion byproducts (CCBs) are four distinct materials.

** Fly ash is the finest of coal ash particles. It's called "fly" ash
because it is transported from the combustion chamber by exhaust
gases. Fly ash is the fine powder formed from the mineral matter in
coal, consisting of the noncombustible matter in coal plus a small
amount of carbon that remains from incomplete combustion. Some fly
ashes are useful for cement replacement in concrete and many other
building applications.

** Bottom ash is coarser than fly ash, with grain sizes spanning from
fine sand to fine gravel. The type of byproduct produced depends on
the type of furnace used to burn the coal.

** Boiler slag is coarser than conventional fly ash and is formed in
boilers, which produce a molten ash that is cooled with water. Boiler
slag is generally a black granular material with numerous engineering

** Flue gas desulfurization (FGD) gypsum is the byproduct of an air
pollution control system that removes sulfur from the flue gas. It is
composed mostly of calcium sulfate. FGD gypsum is most commonly used
for agricultural purposes and for wallboard production.

Source: Coal Ash Research Center, University of North Dakota

Copyright 2007, The News Journal