The dredging of a 40 mile stretch of the Hudson River from 2009-2015 is thought to be one
of the most ambitious environmental and civil engineering remediation projects in the world.
The level of contaminants present in fish in this river was high enough that the government
strongly encourages women under the age of 50 and all children under the age of 15 to
avoid consumption all fish and crabs from the Hudson River south of the Corinth Dam.
So, how did this ecosystem get so contaminated and what actions have been taken to fix it?
In this video, we will describe the types of pollutants that are present in this superfund
site, the harmful effects of these contaminants on human health and wildlife, and the environmental
engineering actions taken under the supervision of US Environmental Protection Agency to cleanup
highly contaminated sections of this ecosystem.
The Hudson is a 315-mile river located in the eastern part of New York state, that rises
from the Adirondack mountains and empties into New York Bay next to New York city.
The Hudson River is a very important habitat to a lot of plants and animals such as the
bald eagle and the American eel.
Several migratory fish spend considerable amount of time in the Hudson.
For instance, adult striped bass and river herrings spend most of their time in the coastal
region but return to the fresh waters of the Hudson to spawn in the spring.
Nevertheless, sections of this river are highly contaminated with polychlorinated biphenyls
(PCBs) that were released from 2 capacitor manufacturing facilities in the towns of Fort
Edward and Hudson Falls, New York.
PCBs were widely used in the manufacture of electrical equipment like capacitors and transformers.
However, in 1977, the industrial manufacture of PCBs was banned because PCBs were linked
to several harmful health effects in humans.
PCBs are thought to be human carcinogens and have been linked to a variety of health issues
such as low birth weight, thyroid disease, learning difficulties, and poor memory.
A mother can pass PCBs to a fetus through the placental cord and to an infant through
the breastfeeding.
For this reason, women under the age of 50 and children under the age of 15 are advised
to avoid consumption of all fish and crabs from the Hudson River south of the Corinth
Dam.
There are also eating advisories for males over the age of 15 and women over the age
of 50.
The presence of this chemical not only threatens humans, but wildlife.
Hence, to protect humans and wildlife it was necessary to clean up the Hudson.
Under the supervision of the EPA and over a six-year period, 40 miles of the most polluted
section of the river from Fort Edward to Troy was dredged, placed in a barge, transported
to a processing site where sediment that was removed was dewatered, and stabilized before
transport to landfills for proper disposal.
On a separate vessel, scientists obtained sediment samples for PCB analysis.
Removed sediment was replaced with backfill and in some areas a cap was installed.
Over 300 acres of riverbed was backfilled.
Backfill material included the use of 100,000s cubic yards of gravel, sand and fine material.
Certain sections of the riverbed where there were still high concentrations of the contaminant
were capped with AquaBlokTM which is a capping system that the EPA thinks will withstand
erosion damage from the river.
It is still yet to be determined if this project was successful.
EPA will now supervise periodic monitoring of the concentrations of PCBs in the water
column, sediment, and fish samples from across the river.
The cap will also be examined at specific intervals and after every high flow event.
I will keep you updated.
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