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Settlement Resolves Chlorine Spills by Connecticut Power Plant

Release Date: 03/03/2010
Contact Information: David Deegan, (617) 918-1010

Boston, Mass. – March 3, 2010) – The owner and operator of a coal-fired power plant in Montville, Conn., AES Thames, LLC, will pay a penalty of $140,000 to resolve alleged violations of the federal Clean Water Act and other environmental laws, arising from releases of chlorine from the plant to the Thames River in 2006.

The settlement is contained in a Consent Decree announced today by EPA. The Consent Decree also resolves alleged violations of steam production limits contained in AES Thames’ Clean Air Act permit.

Under the agreement, AES Thames will pay the cash penalty of $140,000 and take measures to prevent repeat violations, such as training its employees annually in spill prevention and response measures, and updating its spill response procedures to comply with applicable reporting requirements.

In both January and March 2006, AES Thames had accidental spills of sodium hypochlorite (chlorine) into the Thames River. Release of the chemical, which is used to keep cooling water pipes clear of growth, violated the facility’s Clean Water (NPDES) permit. On both occasions, AES Thames also failed to notify emergency response agencies in a timely manner, in violation of the permit and other environmental statutes.

Over several years, AES Thames also violated the heat input limits set forth in its “PSD” permits. Prevention of Significant Deterioration (PSD) permits are issued under the federal Clean Air Act for new and modified major sources of air pollution such as power plants, manufacturing facilities, and other facilities that emit air pollution. PSD permits apply to all pollutants that do not exceed the National Ambient Air Quality Standards (NAAQS) in an area. AES Thames has now applied for and obtained amended PSD permits that correct their calculation of steam flow and heat input. AES Thames is now operating in compliance.

The chlorine releases are not known to have caused specific environmental harm. Similarly, the alleged excess steam production is not known to have resulted in significant excess emissions.

AES Thames has revised and updated its Spill Prevention Control and Countermeasure Plan (SPCC), its Stormwater Pollution Prevention Plan (SWPP), its Chemical Handling and Spill Response Protocol, and its Emergency Action Plan safety protocol, to reflect and emphasize the correct regulatory requirements for reporting spills.

In addition AES Thames will conduct a Chemical Handling and Spill Response training annually for all employees. The training will emphasize the potential impacts of chemical spills, and specifically sodium hypochlorite spills, on the facility’s wastewater treatment system and the environment. AES Thames will assess the effectiveness of its Chemical Handling and Spill Response training program annually by testing those participating in the program to ensure that they are properly trained to handle chemicals and to respond to spills.

More Information:

The consent decree, lodged in the U.S. District Court for the District of Connecticut, is subject to a 30-day public comment period and approval by the federal court. A copy of the
consent decree will be available on the Justice Department Web site at (

EPA Enforcement of environmental laws in New England (

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