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Fact Sheet 4 PCB Contamination Of The Hudson Is Dredging an Appropriate Cleanup Strategy?
What are PCBs and how did they get in the Hudson River?
PCBs (polychlorinated biphenyls) are a class of 209 industrial
chemicals that are very persistent environmental contaminants. These
chemicals were once used widely by industries, like General Electric,
as insulating fluid in capacitors, transformers and electrical systems.
From 1947 to 1977, two General Electric plants (at Fort Edward and
Hudson Falls, New York), discharged from 500,000 to 1.5 million pounds
of PCBs into the Hudson. Over 300,000 pounds remain concentrated in
bottom sediments of the river today. The spread of PCBs throughout the
Hudson River and the food chain which it supports has created one of
the most extensive hazardous waste problems in the nation.
Are PCBs dangerous?
According to the Environmental protection Agency (EPA), PCBs are a
probable human carcinogen. Exposure to PCBs has been linked to a
variety of cancers, including liver, biliary tract, skin and brain. In
addition, recent studies have linked PCB exposure to non-cancer health
effects, including reproductive failure, birth defects, developmental
disorders, and impairments to nervous and immune systems. These
non-cancer health effects have been observed in humans and wildlife
alike; appear at very low exposure levels, and affect not so much the
mothers who may have been exposed to PCBs, but their unborn and nursing
offspring.
Although contaminated fish consumption poses the most potent route of
human exposure, local communities are also at some risk from PCB
releases into air, and from the presence of PCBs in the drinking water
supplies of many communities which draw their water from the Hudson
River.
PCBs are concentrated in the sediments of the river. However, PCBs are
easily swept into the water column and spread throughout the course of
the river and the ecosystem which it supports. It is estimated that
over 90% of the PCBs in the water column of the lower Hudson River
originate from a 40-mile stretch of the upper Hudson River between Fort
Edward and Troy. PCBs from "hot spots" (areas of significant
accumulation) in this area constantly disperse downstream, causing
ongoing contamination of the Hudson River Estuary.
What can be done about PCBs?
The EPA is currently reconsidering a Superfund cleanup of Hudson River
PCB contamination. Under Superfund, a federal program to clean up
hazardous waste, GE could be held responsible for its pollution of the
river, and may have to pay for a comprehensive cleanup. During the
review process, EPA will choose one of several remediation
alternatives, including "no action."
The New York State Department of Environmental Conservation (DEC) has
proposed --- in 1978 and again in 1986--- a plan to remove 3 million
cubic yards of the most highly contaminated sediments, which contain
approximately 250,000 pounds of PCBs. In three separate reviews, both
DEC and EPA have indicated that dredging would provide substantial
environmental benefits with either few or relatively minor
environmental impacts.
The spread of PCBs throughout the Hudson River ecosystem has resulted
in an ongoing and unacceptable threat to the health of local
populations, the greatest concern relating to human health impacts
associated with the consumption of PCB contaminated fish and water. The
dredging of PCB contaminated sediments (with subsequent treatment and
destruction) will permanently reduce the transport of PCBs throughout
the river, which will reduce PCB levels in fish and the water column.
Dredging of PCB contaminated sediment is necessary to reduce human
health risks and to restore our environment.
How would contaminated sediments be removed?
Contaminated sediments would be removed using a cutterhead suction
dredge, a technology designed to remove contaminated sediments while
minimizing resuspension of material within the water column. In a
number of studies, the cutterhead suction dredge has been shown to have
a more effective and efficient design than other dredging equipment,
with the most operational flexibility and the best maneuverability near
shorelines. The cutterhead suction dredge limits resuspension of
contaminated sediments by combining the action of a rotating cutter
with hydraulic suction. Loss of contaminated sediment is minimized by
controlling both the cutter angle and the swing speed of the dredge.
Won't dredging just stir up contaminated sediments?
In studies conducted by the US Army Corps of Engineers (ACOE) during
dredging operations, chemical and physical monitoring of levels of PCBs
in the water column determined that although ambient levels of PCBs in
the water column were raised, the increased levels were not such that
public health or worker safety were threatened. In addition, these
increased levels were confined to the areas in which dredging was
actually taking place.
After conducting a pilot project to dredge PCB contaminated sediment
from the Acushnet Estuary in New Bedford Harbor researchers found that
the cutterhead dredge caused no plume of resuspended material moving
away from the dredging area. Similarly, no elevated levels of
contaminants were detected outside the immediate dredging area. EPA is
now recommending dredging of contaminated sediments as the cleanup
strategy for other PCB contaminated waterways, including the St.
Lawrence River in New York, the New Bedford Harbor in Massachusetts and
the Waukegan Harbor in Illinois. - more - Many other steps could be
take to further reduce the possible effects of removing PCBs from the
Hudson River. For example, dredging would take place during the
low-flow period of the year, between early summer and late fall; this
will minimize the downstream transportation of PCBs. In addition,
dredging could be temporarily stopped during storm events, which
increases the river's flow. Finally, floating booms and silt curtains
downstream will further limit the spread of sediment or debris from the
dredge site.
The EPA has estimated the total possible loss during a hydraulic dredge
project would be 480 pounds of PCBs, which is equivalent to 0.2% of the
total dredged material. Considering that an estimated 2,000 to 5,000
pounds of PCBs wash over the Federal Dam at Troy each year, this is a
relatively small loss.
What will happen to PCB contaminated sediments once removed from the
river?
There are a number of safe, effective and commercially available
technologies to treat and destroy PCBs once removed from the riverbed.
As a result, we are no longer limited to leaving PCBs in place (which
is equivalent to the "no action" alternative), or landfilling
contaminated sediments (which is subject to tremendous public
opposition).
There are two types of technologies which may be used: separation
technologies, which remove PCBs from sediments to produce a smaller
volume of more concentrated PCBs; and destruction technologies, which
break apart PCB molecules. The primary benefit of separation
technologies is a significant reduction in the volume of hazardous
material. However, highly concentrated PCB residuals must be further
treated and/or disposed of, which requires additional cost and
potential off-site transportation.
A preferred alternative is the use of a separation technology (soil
washing) to concentrate PCBs, followed by thermal desorption with
chemical dechlorination in which organic contaminants are volatilized
and key chemical bonds within PCB molecules are broken. At $60 million,
the estimated cost of this complete, on-site alternative is comparable
to land disposal alone (excluding the cost of dredging).
What will happen if PCBs are not removed from the river?
As long as large amounts of PCBs are concentrated in upper river
sediments, they can be effectively removed from the river. However, as
PCB contaminated sediments are scoured up from the riverbed and
dispersed, it becomes next to impossible to recapture them. The longer
PCBs remain in the river, the greater the risk a major flood will wash
large amounts of PCBs into the lower river. As a result, action needs
to be taken as soon as possible.
What can you do to help?
PCBs will not be removed from the Hudson River without two key things:
political will and money. You can help by writing to the Environmental
Protection Agency, urging it to:
Order a prompt and comprehensive cleanup of PCBs from the riverbed.
Use safe, effective and commercially available technologies to
permanently destroy PCBs once they are dredged from the river.
Require GE, the company responsible for PCB contamination of the
Hudson River, to pay for a full and comprehensive cleanup.
Send letters to:
Carol Browner, Administrator Jeanne Fox Regional Administrator
US EPA Region 2 EPA
410 Main Street, NW 26 Federal Plaza
Room 1200, West Tower New York, NY 10278
Washington, DC 20460
For more information on PCB contamination of the Hudson River, including
available cleanup technologies, contact Clearwater's Environmental
Action Program at: 112 Market Street, Poughkeepsie, New York 12601
Phone: 845-454-7673
Email: EnvAction@Clearwater.Org
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Send comments and questions to
EnvAction@Clearwater.org
Updated 6/23/97