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The entrance to the Stony Brook Regional Sewerage Authority on River Road in Princeton.

The U.S. Department of Justice has reached a settlement with the Stony Brook Regional Sewerage Authority in the U.S. District Court for the District of New Jersey that will resolve violations of the Clean Air Act and New Jersey Air Pollution Control Act regulations at the authority’s wastewater treatment plant on River Road in Princeton.

The sewer authority operates three wastewater treatment plants for parts of Princeton, West Windsor Township, South Brunswick Township, Pennington Borough, Hopewell Borough, Hopewell Township, and Plainsboro Township. At the River Road plant in Princeton, the authority incinerates its own sewage sludge and also incinerates sludge generated by other wastewater treatment facilities in the state.

Under the proposed settlement announced by the U.S. Environmental Protection Agency, the Stony Brook Regional Sewerage Authority will bring the facility into compliance with federal and state laws that protect clean air by reducing pollution from sewage sludge incinerators. The Stony Brook Regional Sewerage Authority will pay a $335,750 civil penalty. The authority has also agreed to commit an additional $44,250 to the New Jersey Department of Environmental Protection’s environmental mitigation project fund. The State of New Jersey joined the federal government as a co-plaintiff in this case.

“This settlement means cleaner air for communities in Mercer County with the Stony Brook Regional Sewerage Authority improving how it manages sewage sludge at its Princeton facility,” said EPA Regional Administrator Lisa Garcia. “If not done properly, sewage sludge incineration can pose serious public health risks and this settlement will establish critical safeguards for how the authority manages, monitors, and reports this type of activity.”

The federal government and the state allege that beginning in 2016, the Stony Brook Regional Sewerage Authority failed to develop required plans and operating procedures to comply with the sewage sludge incinerator requirements for the Princeton facility, which burns municipal sewage as a way to dispose of it. Sewage sludge can contain a range of pollutants like mercury, lead, and cadmium that can pose public health threats when the sludge is burned without appropriate safeguards.  

“The proposed settlement is an important step in protecting the environment and public health in Mercer County, and ensuring that the Stony Brook Regional Sewerage Authority facility complies with state and federal laws,” said New Jersey Department of Environmental Protection Commissioner Shawn LaTourette. “We thank Regional Administrator Garcia, the U.S. Department of Justice, and the New Jersey Office of the Attorney General for their efforts on this enforcement action. The DEP will continue to work with our partners at all levels to protect air for every community in New Jersey.”

Under the settlement, the Stony Brook Regional Sewerage Authority must take the following measures at the Princeton facility to bring it into compliance with federal and state clean air laws:

  • Develop plans to monitor the mercury concentration of sewage sludge as an enforceable operating limit;
  • Establish site-specific operating limits to control air emissions and monitor compliance with those limits, and apply for a modification of its existing air emissions permit to incorporate these limits;
  • Establish and maintain procedures to minimize and eliminate bypass events, which result in uncontrolled air emissions.  

The settlement with the Stony Brook Regional Sewerage Authority is part of EPA’s multi-regional initiative to bring municipal sewage sludge incinerator facilities into compliance with Clean Air Act requirements.

After the federal government announced the settlement, the Stony Brook Regional Sewerage Authority issued a press release saying the majority of the violations relate to the authority’s operation of an emergency bypass stack designed to protect the health and safety of employees and the authority’s infrastructure in the rare instances when commercial power or an equipment failure occurs. The authority’s sewage sludge incinerators are designed so that sludge, a byproduct of wastewater treatment, automatically stops feeding in the event of an emergency. According to the authority statement, without the operation of the emergency bypass stack, the exhaust gases would fill areas where employees are present and would damage the incinerator air pollution control equipment. The emergency bypass stack is used approximately 0.04% of the time that the incinerators are in operation and only during events beyond the control of the authority.

During discussions with the Environmental Protection Agency and the state that led to the settlement, the Stony Brook Regional Sewerage Authority took corrective action to comply with the Clean Air Act sewage sludge incinerator requirements prior to the settlement. The Stony Brook Regional Sewerage Authority installed an alternative power supply to minimize bypass events and changed its operating procedures to better anticipate bypass events. The authority does not operate the incinerators in anticipation of severe weather or heavy rainfall, which have been associated with commercial power failures, and has installed an uninterruptible power supply or “UPS system” on critical components that provide emergency power when commercial power fails, in an effort to reduce emergency bypass events.

“SBRSA endeavors to achieve compliance, or perform better than required by its permit at all times, and continuously works to protect the environment. To this end, several years ago, SBRSA installed a Regenerative Thermal Oxidizer (“RTO”). The RTO recycles heat from the exhaust thus reducing the amount of fossil fuels required to maintain temperatures within the incineration system,” reads the authority statement. “The reduced use of fossil fuels and the resulting reduction in adverse emissions are beneficial to the environment.”

In response to the citation for failing to file a plan identifying steps taken to ensure that mercury, dioxins and furans are appropriately controlled, the authority characterized the issue as a “misunderstanding over regulatory reporting.” Local officials said the authority’s daily sampling and monthly analysis of sludge fed to the incinerator, and verification through periodic stack emission testing, “establish that mercury emissions have always been significantly less than the amount allowed under the Clean Air Act and SBRSA’s operating permit. Emissions of dioxins and furans have been negligible. In fact, emissions of all pollutants have always been less than the amount allowed under the Clean Air Act and SBRSA’s operating permit. Under the Consent Decree, SBRSA has agreed to incorporate mercury, furans, and dioxins into future control plans.”

Avatar of Krystal Knapp

Krystal Knapp is the founding editor of Planet Princeton. Follow her on Twitter @krystalknapp. She can be reached via email at editor AT planetprinceton.com. Send all letters to the editor and press releases to that email address.