On August 6 the Environmental Protection Agency (EPA) reported that General Electric had discovered elevated dissolved PCB’s at the Thompson Island dam a mile downstream of the environmental dredging operation to clean remove the contaminants from the Hudson River.
Cashman Dredging is operating eleven barge-mounted excavators equipped with hydraulically-operated clamshell buckets in the cleanup project.
The far-field monitors at Thompson Island registered PCB levels of 528 parts per trillion late on August 6. The drinking water standard is 500 parts per trillion and the downstream communities of Waterford and Halfmoon were informed of the elevated levels.
The samples were taken between Wednesday August 5 at 6 a.m. and Thursday August 6 at 6 a.m. and were analyzed using a comprehensive method that allows for fast processing.
The contaminant levels have been elevated for some weeks said Kristen Skopeck EPA Community Involvement Coordinator. Because of the elevations additional measures have been taken surrounding the dredging operation including setting up silt curtains and absorbent booms and reducing the number of dredges operating in the areas of highest contamination. A silt curtain is installed across the channel and opened for passing vessels. This operation is being closely monitored so that the curtain is not left open for longer than necessary said Skopeck. Other measures are: making sure loaded barges are covered with a layer of water to prevent the material from drying out and releasing PCB’s into the air and avoiding filling the barges completely to avoid overflow.
Near-field real-time turbidity and air quality monitors are in operation in the dredging area and have not registered elevated turbidity or air pollution said Skopeck.
EPA is monitoring the situation carefully and working closely with GE and New York State to ensure the project continues to be conducted in a manner that protects people’s health she said