Old mill examined for answers to Hudson pollution

Toxic materials trapped in tunnel thought to have seeped into bedrock

A natural detective story

March 09, 2001|By Kirk Johnson | Kirk Johnson,NEW YORK TIMES NEWS SERVICE

HUDSON FALLS, N.Y. - For decades, the crumbling limestone walls of the old Allen Mill concealed a secret.

Deep inside, a 150-year-old tunnel and a long-forgotten wooden gate that were part of the mill's early Industrial Era water-power system on the upper Hudson River were slowly rotting away.

Finally, in 1991, the gate failed. A reservoir that had built up in the tunnel - a foul stew of PCBs, solvents and oils that had seeped through the porous shale bedrock from the General Electric capacitor factory just up the riverbank - surged into the Hudson.

The short-term result was a toxic shock to the river and its fish, as PCB levels rose as much as a hundredfold in a matter of months. The larger, subtler impact since then has become a matter of interpretation - the interplay of science and public relations, research and bombast that have become pervasive in the drawn-out story of the Hudson and its pollution.

Environmentalists, government officials and researchers at GE say that the Allen Mill event, as it came to be called, raised most of the big questions about the Hudson and its poisons: where the chemicals come from, how they are transported, and especially how they are to be treated or removed.

And now, as GE and the federal Environmental Protection Agency spar through a public comment period about the government's plan, announced in December, to dredge the river to remove the PCBs, the story of the mill's old wooden gate - and what it says or doesn't say about the river - has been dredged up as well.

GE's views

General Electric officials say the Allen Mill spill solidified the company's conclusions that the area of the old mill and the GE factory, and the sievelike nature of the rock below the factory's old cement foundation, were the basic reasons that PCB levels in the river and its fish were not dropping faster so long after the dumping ended and the cleanup began. The place, they say, probably still holds thousands of pounds of PCBs that are yet to be recovered.

"What it taught us is that source control is the cornerstone of the recovery of the river," said Stephen Ramsey, GE's vice president for corporate environmental programs.

Officials at the EPA say the primary lesson to be drawn from the Allen Mill spill is that PCBs are still pervasive on the polluted factory grounds where they originated, and that the pathways by which the chemicals can travel the river are incredibly complex.

The agency's tests show that lingering levels of poisons in the river's fish cannot be explained by leaks from the company's factories in Hudson Falls and nearby Fort Edward, where GE used PCBs for nearly three decades. It was that finding, among others, agency officials say, that pushed them to propose their dredging plan.

Heart of the matter

At its heart, though, the Allen Mill event is a detective story.

John Haggard, the manager of GE's Hudson River program, was working just downriver from the mill in 1991, testing the sediment and the fish in a place called the Thompson Island Pool - the river's single most contaminated spot - when the first shock wave occurred.

At first, he said, he suspected a lab error. The PCB levels in fish had jumped beyond anything that anyone had ever seen.

"So we started tracing back to where this had come from," he said. "And that took us back to Allen Mill."

The mill, which had been closed for many decades, had largely been overlooked up to that point in the river investigations, because PCBs were never used there. But in tracing the trajectory of the PCB plume, the trail inexorably led to the stark stone building on the water's edge, about 100 yards from the GE factory.

The place was overgrown with trees and bushes that had to be cleared away, and the building had to be tested and then reinforced to ensure its structural integrity before investigators could even go in.

When they did, they found what amounted to a vast collection bucket, partly artificial, partly a result of the fractured geology on the river's eastern shore. PCBs from GE's building, which most geologists had thought would drain back inland because of the slope, had instead collected in the stone recesses of the mill.

150 pounds a week

Working under a consent order with the state of New York, GE ended up spending almost $165 million cleaning up the property with a system of wells, pumps and an on-site water purification plant.

Even now, the company's engineers take nearly 150 pounds of PCBs a week from the ground water in and around the Allen site.

Scientists say that after the PCBs were found in the Allen Mill, some elements of the investigation were subtly altered.

Efforts to determine how much the PCB oils in the river had aged or weathered, for example - through so-called dechlorination from exposure to the elements - became more important, since answering that question would give scientists a clue about the relative release time of the chemical into the water.

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