Contamination Site Becomes Cleanup Lab

Black sludge undulates under tea-colored water as Dave King lifts a container to the light. Dirt reeking of mothballs fills another jar. A walnut-size ball of tar rolls around in a third.

The samples are remnants of the gaslight era, left over from a time when this city was the nation’s largest energy producer.

The Harbor Point gasworks were torn down long ago. Gone too are the factories they fueled, leaving this city struggling for economic survival. But the byproducts of the days when gas was made by cooking coal remain, polluting soil, ground water and river sediment.

King heads a team of researchers studying ways to deal with the buried tar, sludge and chemical residues. Utility groups and a federal grant have supported the work, which could provide information useful in the cleanup of thousands of similar sites across the country.

Harbor Point is a 65-acre site formerly used by two manufactured gas plants and now owned by Niagara Mohawk Power Corp., King’s employer. The site was ideal for developing sampling and cleanup methods because of the variety of chemicals in the 600,000 tons of contaminated soils here, King says.

There are thousands of sites around the country where coal tar and other residues are buried, sites that once held gas manufacturing plants. Only 14 are among the 1,200 sites on the U.S. Environmental Protection Agency’s Superfund priority-cleanup list.

“That doesn’t mean that the other sites pose no problem,” said Marlene Berg, a scientist with the Superfund program. Many are being cleaned up under state authority rather than federal, she added.

There are known and suspected cancer-causing agents in the waste, including benzene, toluene and xylene.

But David Sterman, a deputy commissioner in New York’s Department of Environmental Conservation, said the risk to human health is generally low unless contaminants seep into water supplies, are exposed during excavation or are in areas used by the public.

As utilities have sought to market real estate--as Niagara Mohawk eventually hopes to do at Harbor Point--the cleanup has become more urgent, says King, who runs Niagara Mohawk’s manufactured-gas plant program.

Cleanup also has become a priority in communities in which contamination has been found beyond industrial areas.

Residues have been found in sediment dredged from rivers, including New York’s Mohawk River, the Big Sioux River in South Dakota and the Flat River in Michigan.

In Taylorville, Ill., parents blamed gas-plant chemicals in the air and ground water when five children contracted a rare form of cancer. State and utility studies found no evidence of a connection between the waste and the illness.

The gaslight era, between 1830 and 1915, fueled the Industrial Revolution. Before that, light was provided by candles and whale-oil lamps. Easy access to coal shipments via the Erie Canal allowed dozens of gasworks to locate across central New York. Factories followed.

The gas wasn’t the natural gas used today, but a product manufactured by cooking coal. Oven workers shoveled coal into large “retorts,” where it was heated to give off methane gas. As the gas was cooled, tar and oil byproducts flowed into a storage tank. A purifier removed ammonia, which was stored, and sulfur, which was absorbed by wood chips.

The gasworks became obsolete with the advent of electric lights and an interstate network of pipelines supplying natural gas. They left a variety of contaminants, mainly tar, sludges, oils and cyanide compounds. The waste was disposed of in pits, ponds and landfills.

At Harbor Point, bordered by vacant industrial land and the Mohawk River on the fringe of the city, King displays jars of waste products found in some of the 150 test wells drilled on the site.

There’s coal tar emulsion, the molasses-like stuff used in driveway sealer. It floats on water colored brown by soluble waste compounds. The densest byproduct is tar, which is heavier than water.

In seven open-faced sheds, half-ton hills of soil and rock dug from different areas are sheltered for testing. Some piles have visible gobs of tar. The rotten-egg smell of sulfur wafts from a pile of purifier waste, which includes wood chips stained bright blue by cyanide compounds.

Holding ponds contain runoff water that is pumped through a treatment plant.

“When we started this in the mid-’80s, there was really nothing in the literature about the technology options,” King says. “We decided to research and do full-scale testing of technologies to clean up soil and ground water.”

Scientists chose several approaches as the most promising.

Tar-contaminated soil was used to pave roads throughout the site. Soil was trucked away and used in the making of bricks and in roofing and cement. Chemicals were destroyed by heating soil or washing it with solvents.

Some waste materials can be burned in licensed incinerators. There was some success in getting bacteria to eat compounds in harbor sediment. In some instances, an impermeable barrier could be used to entomb the toxins.

There also were some rejected projects.

“We looked at pumping tars out of the ground to use for heating, hot water, hot air, steam,” King says. “We pumped 240,000 gallons of ground water and got less than 40 gallons of tar. It’s not worth it.

“The study now is evaluating all these options as far as feasibility and cost.”

The EPA initially estimated that cleanup would cost about $25 million per site. Now it appears it will cost $5 million to $10 million, King says.

So far, Niagara Mohawk has spent $30 million on researching and beginning the cleanup of coal gas sites, King says. That cost is passed on to utility customers.