The 315-mile-long Hudson River, which flows in the eastern part of New York state from high in the Adirondack Mountains down to the Battery in New York Harbor, has always been a pivotal waterway in the U.S.—for business and pleasure. Boating, swimming and fishing have long been popular there, but residents who live along the upper Hudson, in particular, know better than to eat the fish.
That's because the river's industrial past has spurred one of the nation's largest and most complex environmental cleanup projects to date: the removal of 2.65 million cu yd of sediment laden with polychlorinated biphenyls, or PCBs, a group of chemicals classified as probable human carcinogens that accumulate in the fish and work their way up the food chain.
The job of reducing the concentration levels of these chemicals in the river and fish is the focus of General Electric's $1-billion dredging project along a 40-mile, heavily contaminated stretch of the Hudson River, from Fort Edward to Troy.
The 10- to 11-year, two-phase project is one of the most complex of its kind in the U.S. It involves roughly 350 workers, more than 70 project-related vessels, heavy machinery and a 110-acre, PCB-dedicated processing and dewatering complex at Fort Edward in the upper Hudson. Despite the scale and scope of the work, questions remain as to whether the effort goes far enough to remove the pernicious toxins.
PCBs have a long history in industry. From 1947 to 1977, GE used oil-based PCBs in capacitors and transformers, which GE manufactured at its Fort Edward and Hudson Falls plants on the upper river.
Over the decades, the plants discharged up to an estimated 1.3 million lb of PCBs into the Hudson. Like other manufacturers, GE was following a common practice along what was then a heavily industrialized river. The company had permits for most of its discharges.
But by the mid-20th century, a growing body of research suggested that PCBs posed a threat to health and the environment. As those findings gained more substantiation, regulators issued fish-consumption advisories in 1971 for the river. The U.S. Environmental Protection Agency bannned PCB production in 1979 and, by 1984, had declared a 200-mile span of the Hudson River a Superfund site. For decades, GE, the government and key stakeholders would tussle over what to do to about the PCB issue—and who should do it.
In 2002, GE agreed to pay for and dredge what were dubbed "hot spot" PCB areas in the river. That same year, EPA issued a record of decision (ROD) for dredging the 40-mile stretch, designated as River Sections 1, 2 and 3, in two phases. The plan still guides the effort today.
In 2007, before the dredging started, GE began building the Fort Edward processing and dewatering complex as well as a separate collection tunnel beneath the river to collect PCBs infiltrating from its Hudson Falls site. (See this sidebar on why PCBs are so persistent in the environment.)
Phase-one dredging began and ended in 2009. Phase two started in 2011 and is expected to be completed by 2017 or 2018. Meanwhile, last June, EPA issued a five-year review of the project so far that shows the cleanup is going according to plans outlined in the ROD. While some groups, including environmentalists, do not necessarily disagree with the findings, they claim the ROD itself is flawed because it does not take into account all of the hot spots and say the effort will leave significant contamination in the river long after project completion. They want the EPA, which oversees the project, to expand the scope and time frame of GE's cleanup. EPA "has issued a final decision, and we're following it," says Mark Behan, a GE spokesman.
Despite the controversy, all parties involved in the cleanup agree the project itself is a major design and engineering feat.
"People who haven't seen the project don't really fully appreciate the complexity of it," says John Haggard, GE executive director of the project. "Prior to getting this under way, there was almost no precedent for this."
The work starts with the excavators, each equipped with clamshell buckets to scoop contaminated debris from what, in some places, is a non-uniform river bottom.
"We have to deal with everything in the river. One day it's a cobble field where there are boulders and course sands and gravel," says Timothy Kruppenbacher, GE operations manager. "Other days, we have to dig over the tops of clay—and you get blocks of clay—or your silts, which we refer to as 'pudding' in the barges."
Each dredge is equipped with GPS technology to help guide the buckets to their targets with what some call "surgically precise" accuracy.
Separate barges loaded with clean sand and gravel follow the dredges to backfill the cuts. Work continues in the dredge zone around the clock, six days a week, during the work season from May through November.
Other barges loaded with contaminated sediment are sent upriver to the Fort Edward processing complex. Along the dredge zone, air, water and noise monitoring systems are in place to alert officials to adverse conditions.
From the roughly 350 project-related workers, including consultants and contractors, to the number of vessels, the amount of equipment and the process itself, the project takes extensive coordination, says Behan. The project must both take into account the dredging operations and accommodate the community that surrounds it, he says. To minimize the noise impact to residents along the river, "whisper-quiet" hospital-grade generators and downward-facing lighting are used on dredging equipment. To track vessels on the water 24/7, GE set up a traffic control center to monitor all the machinery and operations.
In recent years, several U.S. PCB-contaminated waterways have begun evaluation and remediation efforts, though none are tackling such a large section of river as the Hudson project. Wisconsin's Fox River project, for example, started in 2009 and aims to remove or cap 3.8 million cu yd of contaminated sediment. Although that is more than the Hudson project in scope, it only covers a 13.3-mile stretch of the river (ENR 8/3/09 p. 24).