DEC Announces Completion of Second Phase Thermal Treatment to Address Contamination at Former Grumman Settling Ponds

Progress Continues on protecting Drinking Water from Larger Navy-Grumman Plume with More than 276,000 Pounds of Contaminants Removed to Date

New York State Department of Environmental Conservation (DEC) Commissioner Amanda Lefton today announced Northrop Grumman contractors completed 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. The milestone builds on the ongoing progress being accomplished with DEC's comprehensive plan to contain and clean up the groundwater plume associated with the Northrop Grumman Bethpage Facility and Naval Weapons Industrial Reserve Plant sites in the town, with more than 276,000 pounds of contamination removed to date.

 "The completion of this phase of the thermal cleanup is a major step forward as DEC continues to push Northrop Grumman to expeditiously clean up Bethpage Community Park to return it to full community use," said Commissioner Lefton. "Governor Kathy Hochul and DEC are working collaboratively with community leaders on multiple fronts to address the legacy contamination left behind by Grumman and the Navy so that the region's drinking water and the health and safety of all residents are fully protected." 

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 side of the park. These wells have successfully treated more than 1.6 billion gallons of water since operation began in 2009, and the system has removed more than 2,600 pounds of VOC contamination.

Following a successful initial phase of the thermal cleanup from August 2020 to May 2022, which removed approximately 1,400 pounds of 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 second phase consisted of an area between the tennis courts and the skate park.  

During Phase 2, data from operating the extensive thermal system which consisted of more than 380 thermal remediation wells, was used to determine that the remedial goal for this phase was met. This scientifically proven and safe cleanup method removed over 460 pounds of volatile organic compound contamination during this phase.

Combined, the thermal remedies removed nearly 1,900 pounds of VOCs and required 17 million kilowatt-hours (kWh) of electrical power. Completion of the two thermal remedies and the continuation of the groundwater extraction wells removed source material while protecting the community and preventing contaminants from leaving the park. Phase 3 will address hotspot contamination in a third area of the park, located beneath the parking lot. 

DEC continues to closely oversee work in the former Grumman settling ponds to ensure the system is maintained and operating effectively. Last 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 and safe removal of the 22 concrete-encased drums 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 worked with its partners at the federal, State, and local levels to ensure a comprehensive, park-wide geophysical investigation was completed.

Northrop Grumman is currently developing 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. 

Navy Grumman Groundwater Plume / Water Quality
An extensive system of wells continues to prevent contaminants from leaving the park boundaries and monitoring shows that a clean front of groundwater is developing downgradient of the site.

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.    

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.

In addition to the Bethpage Community park cleanup, DEC is advancing a comprehensive plan to contain and clean up the larger groundwater plume directly associated with the Northrop Grumman Bethpage Facility and Naval Weapons Industrial Reserve Plant sites in Bethpage. The full containment of this groundwater plume will prevent the further spread of contamination to water supplies in neighboring communities and provide peace of mind to local residents. As part of existing legal commitments, both the Navy and Northrop Grumman continue to operate three separate groundwater extraction and treatment systems. This includes 11 extraction wells pumping at a combined rate of approximately ten million gallons per day. More than 276,000 pounds of contamination have been removed from the aquifer since these systems began operating in fall of 1997.