Originally published as a Schiff Hardin Environmental Update newsletter

On March 21, 2011, the long-awaited Industrial Boiler MACT rules, released by the United States Environmental Protection Agency (USEPA) on February 21, 2011, were published in the Federal Register. Under the Clean Air Act, USEPA is required to set national emission standards for hazardous air pollutants (NESHAPs) based on the performance of the maximum achievable control technology (MACT). The new rules address both (1) industrial, commercial and institutional boilers and process heaters for “major” sources (76 Fed. Reg. 15608); and (2) industrial, commercial and institutional boilers for “area” sources (76 Fed. Reg. 15554). A major source facility emits or has the potential to emit 10 or more tons per year (tpy) of any single hazardous air pollutant (HAP) or 25 tpy or more of any combination of HAPs. An area source facility has the potential to emit less than 10 tpy of any single HAP or less than 25 tpy of any combination of HAPs.

The original Industrial Boiler MACT rule was issued in 2004, but was vacated by a federal court of appeals in 2007. USEPA has been under a court order to finalize the new Industrial Boiler MACT rules by December 16, 2010. Due to the voluminous comments, USEPA sought to extend the deadlines, but the court eventually ordered promulgation by February 21, 2011.

Area Sources

At area sources, the Industrial Boiler MACT rules create emission limits for mercury, particulate matter and carbon monoxide for all new coal-fired boilers with heat input greater than 10 million British thermal units (Btu) per hour and particulate matter emission limits for new biomass and oil-fired boilers. New boilers with heat input below 10 million Btu per hour will be required to undergo a boiler tune-up every two years. For existing boilers, the new rules create emission limits for mercury and carbon monoxide only for coal-fired boilers with heat input greater than 10 million Btu per hour. USEPA did not establish emission limits for existing boilers with heat input less than 10 million Btu per hour. Rather, those boilers must undergo a tune-up every two years.

Major Sources

Industrial boilers at major sources (facilities that emit ten or more tons per year of a single HAP or 25 or more tons per year of any combination of HAPs) are subject to emission limits for mercury, dioxin, particulate matter, hydrogen chloride and carbon monoxide. The only exceptions for boilers at major sources are for natural gas and other “clean fuel” burning boilers, and those boilers with heat input capacity below 10 million Btu per hour. These boilers are not subject to emission limits. They must adhere to work practice standards.

The rules have evolved over time. The major changes since the initial proposal include the addition of work practice standards for small new boilers, limited use boilers, and for periods of startup, shutdown and maintenance. The area source rule also favorably treats area-source biomass and oil-fired boilers. Boilers that burn at least 15% biomass and oil-fired boilers at area sources are not required to meet emission limits, but rather must perform a boiler tune-up every two years.

A proposal for reconsideration of certain portions of these rules was published simultaneously in the Federal Register. USEPA states it was rushed to promulgate the rules per court order and it believes that specific elements of the rules would benefit from additional public comment and consideration.

The rules become effective 60 days from the date of publication, or on May 20, 2011. Emission limits for existing units will become effective in 2014, and work practice standards will become effective on May 20, 2012 (one year from the date the rule becomes effective). The final rules can be downloaded here.