The Dredging of the Hudson River

The Hudson River’s impact on American history is nothing short of stunning. For millennia, the Hudson has showered riches on the region: bountiful food, scenic vistas, and an important transportation route, to name a few. Today, a new chapter awaits the river. The mighty Hudson is poised to become the nation’s biggest environmental cleanup story—or else a lesson in how not to clean a toxic waste site.

The removal of PCBs from the Hudson has been a long time coming. For decades, General Electric dumped contaminants into the river, fought long and hard against a cleanup, all the while denying health problems relating to the polychlorinated biphenyls, the collective name for the group of 209 synthetic compounds better known as PCBs. But then in 2002, 18 years after nearly two-thirds of the Hudson was designated a Superfund site, GE did an about-face.

On May 15, 2009, the dredging of the Hudson River began.

“It’s the most challenging project I’ve ever worked on,” says David Rosoff MS’90 (geology), the Hudson River on-scene field coordinator for the Environmental Protection Agency and one of two alums associated with the Nicholas School who are working on the project. “It’s a challenge to work with the best people in this industry. … Technically, the challenges are immense—controlling re-suspension; dealing with quality-of-life issues; working six days a week, 24 hours a day, very close to residents; dealing with noise, lights, and odor complaints; the extensive amount of data that we have to look at every day.”

The cleanup covers the upper 40 miles of the roughly 200-mile Superfund site that runs from Hudson Falls, N.Y., all the way to New York City. The pressure on Rosoff and his EPA team seems as intense as the project’s scope is vast.

Says Rosoff, “This is going to be a benchmark for environmental dredging.”

A Contaminant Runs Through It

The Hudson flows from its primary source high in the Adirondacks—Lake Tear of the Clouds on New York’s tallest peak, Mount Marcy—to the tip of Manhattan. Between Albany and the Battery, the river is a tidal estuary, something the Lenape Indians must have sensed—Muhheakantuck, their name for the Hudson, means “river that flows two ways.”

Throughout, the Hudson teems with life, from the phytoplankton at the base of the marine food web to underwater plants that host invertebrates, and on up the chain. More than 200 fish species swim it—from important anadromous types like sturgeon, shad and striped bass to mollusks, crabs, and shrimp. Archeological findings indicate Hudson fish have fed humans for millennia. Today bald eagles, peregrine falcons and snowy egrets call its environs home and hunting ground.

A nexus of recreation, culture, and commerce, the Hudson journeys through landscapes that inspired the Hudson River School, passes by West Point—George Washington’s “key of America”—and streams past the estates’ of artists (Washington Irving), inventors (Samuel Morse), U.S. presidents (FDR and Martin Van Buren) and other American titans (Frederick Vanderbilt and John D. Rockefeller). Dotting the riverbanks are industrial sites past and present—from foundries, paper mills and power companies to plants of corporate powerhouses like International Paper, General Motors and GE.

For much of the last century GE operated two capacitor-producing plants in Hudson Falls and Fort Edward, using its own blend of PCB oil—trademarked Pyranol—as an electrical insulator. In the eyes of electrical equipment manufacturers, PCBs were a “miracle” chemical because of their stability and inflammability—the very characteristics that make PCBs environmentally dangerous.

From the 1940s through 1977 GE’s two plants discharged about 1.3 million pounds of PCB-contaminated waste into the river.

“That was just the standard back then,” says Rosoff. “If you have waste, you put it in a river.”

Part of the trouble with this waste stream is that it lingers and is carcinogenic.

In 1966, a report in the British journal New Scientist gave rise to new concerns over PCBs, concerns that date back to the thirties, shortly after Monsanto began producing them. In studying DDT, Swedish chemist Soren Jensen happened upon the startling fact that PCBs are everywhere: “in his own, his wife’s and his baby daughter’s hair. As the baby is only five months old, her father concludes that she got her dose of PCB with her mother’s milk.” (“Report of a New Chemical Hazard,” New Scientist 32 (1966), p. 612.) A flurry of reports followed.

As early as 1971, The New York Times cited “possible health hazards” associated with PCBs along with warnings by Nobel scientists that PCBs could damage ecosystems “irreversibly” on a global scale. Around the same time, PCBs started showing up in Hudson River fish, and then the first actions were taken to protect human health.

“Most people aren’t in contact with PCBs in the riverbed,” explains Rosoff. “However, the fish are, and the fish are consumed by people. As a result of heavily contaminated fish... the Department of Health in New York State issued a ban of all consumption of fish in the upper 40 miles of the Hudson.”

That was in 1976; the ban is still in effect. The destruction of the fisheries, so vital to the region’s economy, was one of the first victims of the widespread PCB release. Says Rosoff, “The hopes of this project are to return the Hudson to a usable resource and to eliminate the potential risk people have from consuming fish from the river.”

By 1977 the federal government’s concerns over the health risks PCBs posed reached a tipping point: the Toxic Substances Control Act essentially prohibited the U.S. manufacture and sale of PCBs.

But long after GE stopped using PCBs, the chemicals are still Around—and still leaking from the Hudson Falls plant into the river. (GE is conducting a separate cleanup under New York State’s supervision to remove contamination from the plant site and plug the source.) The problem has spread downriver: each year about 300-500 pounds of PCBs cross over the Troy Dam into the lower river.

Back in 1984 when the river became a Superfund site, remediation wasn’t seen as an option.

“The technology in the 1980s didn’t exist to dredge the river without unacceptable levels of resuspension and redeposition,” explains Rosoff. That was then.

Anatomy of Today’s High-Tech Dredging Project

Fast-forward to 2002. With cutting-edge dredge tools available, the EPA determined the PCBs must go. And so began design work followed by construction and a raft of sediment sampling to locate the worst areas of contamination.

In the spring of 2009—the quadricentennial of Henry Hudson’s sail up the river that took his name—GE started “pinpoint” dredging, using the Global Positioning System (GPS) satellite navigation network and a bucket-load of other high-tech, much of it custom-built for the project.

“This is the most state-of-the-art, advanced equipment out there,” explains Rosoff.

Plugging some 50,000 data points into a Geographical Information System (GIS), General Electric created detailed maps of the dredge targets.

“Those maps [are]... on the dredge barges … hooked into a GPS system which is used to position the bucket to do cuts,” says Rosoff.

Sensors on each moving part of the bucket and excavator tell operators exactly where in space they are and how deep they must dig. Another mechanism prevents dipping beyond the pre-determined scoop specs. Thus the pinpoint accuracy of PCB hot spots.

“Overall, the remedy is a mass reduction remedy,” says Rosoff. “We’re trying to remove a large volume of the PCBs … as opposed to trying to remove all the PCBs from the river, which is impossible.”

This dredging project’s initial phase, to last through October, entails bank-to-bank removal of contaminated sediment in the Superfund’s upper six miles. A peer-review process will follow, after which GE and EPA will make any necessary adjustments. Phase II, expected to last about six years, will tackle the remaining 35 miles.

Rosoff reports that the progress is going well, but not “without bumps in the road.”

Three months in, 115,000 cubic yards of sediment had been removed but without meeting cleanup targets. By late September, dredging had been completed and backfilling begun in two areas, but the sediment turned out to be more contaminated than expected. That meant a slightly slower pace—new, deeper cutlines had to be drawn, followed by residual dredging. GE can opt to cap the contaminants.) Such learning as they go makes this foray a critical part of the project.

“I wouldn’t call Phase I a test case,” says Rosoff, “but it’s certainly going to be evaluated heavily for the much longer and more voluminous Phase II.”    

Keeping the Community Safe and Informed

Whether one is a long-time resident of the area or someone just passing through, it’s impossible not to notice something going on. While various tug, personnel, and monitoring boats run the river, dredgers work it, all day and night, except for Sundays. Lights illuminate the nighttime work. Monitors in bright-orange casing sit in the river and pepper its shores, measuring light and noise levels and air and water quality, and standing as visual reminders of the kind of quality-of-life standards at the project’s core.

“The project has a lot of parameters to keep the public safe and minimize disturbance to their daily lives,” says Melanie Chapman MEM’06, an environmental scientist with Ecology & Environment (E&E), one of the consultants working with EPA. “There are a lot of things going on … not only in the river but in people’s backyards as we do floodplains work. (See sidebar.) There are also new people in the area. There’s vehicular traffic.”

As a check on GE’s own monitoring and reporting, Chapman’s team inspects the cleanup site and investigates potential disturbance issues:

“Is the project too loud? Is there light shining on someone’s house in the middle of the night? Is there an odor preventing people from being outside and enjoying their yards?”

While navigation and odor issues must be relayed by the public, noise and light have specific numerical standards not to be exceeded.

Most important are the air and water quality standards. If those are not met, action is swift.

On several occasions elevated levels of PCBs have been detected in the air and water near some of the dredging sites. EPA has responded immediately, cutting back on dredging, putting up windscreens to catch the off-gassing of excavated sediment, and covering hot sediment with water. Longer-term adjustments are also in the works. “Air issues will have to be looked at closely for Phase II,” says Rosoff.

“We’re pushing GE harder to put more engineering controls in place to prevent these air conditions,” says Rosoff, who notes that past projects have not had such extensive monitoring or public involvement.

Daily updates and information on PCB levels are available through an EPA Web site (www.hudsondredgingdata.com). Informational flyers are handed to boaters at the locks. Community meetings are held regularly so that residents can learn directly about the project’s many moving pieces.

Getting the community onboard with the project had been a tall hurdle. GE had spent years and millions spreading a PR campaign against any kind of cleanup and downplaying the hazards of PCBs. But when the tide turned and scientific information about PCBs was widely publicized, the community largely came around.

Of course, it doesn’t hurt that the influx of regional workers also might have jump-started the local economy.

Rosoff lacks hard numbers, but says, “We’ve spoken to several business owners who have related to us an increase in patronage.”

Still, at times, the imposition to the sleepy hamlet is palpable. At a community meeting in mid-July, residents aired a number of grievances. Chief among them were noise and air quality complaints.

“We’re dredging in some of the worst places in the river and the dredged sediment is off-gassing,” says Rosoff.

“For air emissions,” he continues, “the standards we use are for chronic exposure over a six-year time frame, so one day of an exceedance is not an issue from a health standpoint.”

It’s when there’s a trend, he says, that big adjustments must be made.

With short-term controls in place, EPA and GE are working on longer-term fixes. And they are keeping lines of communication open.

“We’re talking to the entire community and entire world about what happens when you remove this type of gross contamination,” says Rosoff.

If people recognize the disturbance aspect of the project, many also recognize the importance of cleaning up the PCBs.

Rosoff underlines the need to succeed.

“The local community … and future projects all over the country are depending on our success,” says Rosoff. “So there is a heavy burden, not knowing whether or not the project is going to work the way it’s been planned because we’ve never done anything at this scale.”

He sees the restoration as a chance to return the historic river to its former magnificence, where its fish are plentiful and safe to eat.

“Perhaps down the road,” says Rosoff, “Fort Edward and the upper Hudson River won’t be known for PCBs but instead for the place of serenity and beauty that it is.”