DEC Announces Second Phase Thermal Treatment to Address Contamination at Former Grumman Settling Ponds to Start Sept. 4

New York State Department of Environmental Conservation (DEC) Interim Commissioner Sean Mahar today announced Northrop Grumman contractors will activate the second phase of the thermal cleanup at the former Grumman settling ponds in Oyster Bay, Nassau County, to address contamination deep in the soil below portions of the present-day Bethpage Community Park. This scientifically proven and safe cleanup method ensures the protection of public health and the environment as part of the State's ongoing and comprehensive investigation, containment, and cleanup of the Navy-Grumman groundwater plume.

"The health of the Bethpage community is New York State's top priority and, under the direction of Governor Kathy Hochul, DEC is holding Northrup Grumman to a strict schedule to ensure the comprehensive cleanup of the park proceeds expeditiously and stays on track," said Interim Commissioner Mahar.  "Implementation of the thermal remedy to address deep contamination at the former Grumman settling ponds is the next step in this process and we look forward to continuing our work with the community to advance an effective and lasting cleanup that protects water quality by preventing the further spread of the Navy-Grumman groundwater plume and fully restores the park for all residents to safely enjoy."

Since 2009, DEC has overseen the capture and treatment of groundwater leaving the park, ensuring trichloroethylene (TCE) and other volatile organic compound (VOC) contamination does not continue to contribute to the spread of the Navy-Grumman groundwater plume. This remedial measure is accomplished through the operation of six strategically placed groundwater extraction wells pumping at approximately 210 gallons per minute, creating a barrier along the downgradient site of the park. The thermal heating treatment directly addresses contamination deep underground and mitigates any potential public exposure to the contamination.

Following a successful initial phase of the thermal cleanup from August 2020 to May 2022 to address TCE and other contamination in deep soil (approximately 35 to 45 feet beneath the ground surface) in and adjacent to the former ballfield area of the park, Northrop Grumman contractors began the construction of the second phase of the thermal remedy in late 2023. The first phase of the thermal remedy removed more than 1,500 pounds of contamination and the groundwater extraction wells continues to prevent contaminants from leaving the park. The wells have successfully treated more than 1.3 billion gallons of water since operation began in 2009, and the system has removed more than 2,500 pounds of VOC contamination.

During Phase 2, data from extensive soil sampling drove the scientific analysis, design, and drilling of more than 380 thermal remediation wells. Phase 3 will address hotspot contamination in a third area of the park, with work starting upon decommissioning of the equipment used in Phase 2.

Thermal heating is a proven, safe, science-based cleanup method that involves inserting metal rods into the ground at approximately 30 to 60 feet below the surface and applying electrical current. The energy created by the electric current heats the soil to temperatures of 100 degrees Celsius (212 degrees Fahrenheit) to vaporize both the VOCs and water in the soil. Vapors are then safely removed by applying a continuous vacuum suction process that brings them to a specialized treatment system at the surface. The system then fully treats the recovered vapors to remove contaminants before treated air is released. This thermal treatment includes a series of temperature and monitoring points in and along the margins of the treatment area to demonstrate the vacuum is operating effectively in the treatment area. As required, Northrop Grumman is conducting air monitoring in the work area and along the margins of the former ballfield to ensure there are no off-site impacts and the health of the adjacent community is protected. DEC continues to rigorously oversee work in the former Grumman settling ponds to ensure the system is maintained and operating effectively.

Earlier this year, during the final drilling of wells for the second phase of the thermal cleanup, Northrop-Grumman's contractors discovered and removed 22 concrete-encased drums in the former Grumman settling ponds area of the park, which is where the bulk of disposal took place while the property was owned by Northrop Grumman. While the discovery presented no threat to public health and safety at the site, DEC's oversight of the thermal cleanup led to the important discovery of the buried drums and DEC continues to work with its partners at the federal, State, and local levels to ensure a comprehensive, park-wide geophysical investigation is completed to determine whether additional buried drums are present in other areas of the park. The investigation will continue in parallel with the Phase 2 thermal cleanup and is anticipated to be completed during fall 2024.

While the thermal cleanup is implemented, Northrop Grumman will develop plans to excavate soil containing PCBs and metals from the former Grumman settling ponds area and dispose of it off-site. This work will proceed after the required agreement is reached between the property owner, the town of Oyster Bay, and Northrop Grumman on a scope of work that will be submitted and subsequently approved by the U.S. Environmental Protection Agency. Once approved, the excavation will be performed in accordance with DEC-approved work plans following completion of Phase 2 of the thermal remedy.

Navy Grumman Groundwater Plume / Water Quality
An extensive system of wells continues to prevent contaminants from leaving the park boundaries. Regular groundwater sampling at the park property boundary shows a downward trend in contaminant concentrations since this system began operating in 2009.

This Groundwater Containment System includes a total of six groundwater extraction wells and four primary wells. Monitoring shows that a clean front of groundwater is developing downgradient of the site.

The Bethpage Community Park groundwater containment system:  

• Prevents remaining contamination from continued migration off-site;
• Removes contamination from Bethpage Community Park; and
• Protects the Long Island aquifer system and the downgradient public water supplies.

The thermal remedy announced today is the second of three phases designed to comprehensively cleanup source contamination in Bethpage. DEC will continue to push Northrop Grumman to expeditiously clean up the park and return it to full community use.

A recent site history is available at the DEC website.

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