EPA Issues Final Adjustments to “Boiler MACT” Hazardous Air Emissions Rules

January 9, 2013


On December 20, 2012, EPA issued final “adjustments” to its rules regulating emissions of hazardous air pollutants from industrial, commercial and institutional boilers and process heaters at major and non-major (known as “area”) source facilities of air toxics. A major source facility emits or has the potential to emit more than 10 tons per year of any single air toxic or 25 tons per year of any combination of air toxics, and an area source facility emits less than 10 tons per year of any single air toxic and 25 tons per year of any combination of air toxics. According to EPA, most of the nation’s approximately 1.5 million boilers will not be affected by the rules, with only approximately 2,300 boilers—mostly large, coal-fired boilers located at industrial plants— - being required to meet numerical emission limits, and another approximately 197,000 boilers being required to comply with work-practice standards, such as annual tune-ups. The majority of boilers, approximately 1.3 million small, natural gas-fired boilers, are not covered by these rules.

EPA promulgated the initial boiler rules on March 21, 2011, and simultaneously announced its intent to reconsider certain provisions of those rules. On May 18, 2011, EPA published a notice delaying the effective date for the major source rule until the earlier of completion of its reconsideration of, or judicial proceedings regarding, the rule. However, on January 9, 2012, the U.S. District Court for the District of Columbia vacated the delay notice and, as a result, the March 2011 rules have been, and will be, in effect until the December 20, 2012, rules are published in the Federal Register.

The revised rules maintain the structure of the March 2011 rules but provide limited additional flexibility, including additional boiler subcategories and alternative monitoring approaches for some pollutants. The revised rules also modify the emission limits for most subcategories of boilers at major source facilities, with approximately 30 percent becoming more stringent, 50 percent becoming less stringent, and 20 percent remaining unchanged.

New and existing boilers at major source facilities will have until three years after publication in the Federal Register of the final rules (i.e., 2016) to comply. Existing boilers at area source facilities must comply with the final rules beginning March 2014, while new boilers and boilers that commenced operations after June 4, 2010, at area source facilities must comply with the rules by the later of May 20, 2011, or start-up.

The major source rule sets numeric emissions limits for mercury, particulate matter or total selected metals, hydrogen chloride and carbon monoxide for 19 (raised from 15 in the 2011 rules) different subcategories of major source boilers and process heaters, and eliminates the numerical emission limits for dioxin/furan in the 2011 rule and replaces them with work-practice standards. The major source rule also includes the following requirements, which are generally unchanged from the March 2011 rule:

  • Monitoring to assure compliance with emission limits. The revised rule provides some monitoring alternatives not present in the 2011 rule, including, in some instances, the use of either continuous emissions monitoring or continuous parameter monitoring; and monitoring for particulate matter, as a surrogate for toxic metals such as lead and chromium, or total selected metals.
  • For all new and existing units smaller than 10MMBtu/hr, and all new and existing natural gas- and refinery gas-fired units, the rule establishes work-practice standards in lieu of emissions limits, including a requirement to perform a tune-up for each unit every two years (for units under 10MMBtu/hr) or annually (for gas-fired units).
  • Existing major source facilities must conduct one-time energy assessments to identify cost-effective energy conservation measures.

The area source rule includes the following requirements: 

  • New coal-fired boilers larger than 10MMBtu/hr will be subject to numeric emissions limits for mercury, particulate matter, and carbon monoxide, while existing units will be subject to limits for mercury and carbon monoxide. 
  • New biomass- or oil-fired units larger than 10MMBtu/hr will be subject to limits for particulate matter, while existing units will be required to employ specific work practices, including maintenance every two years.
  • Most new and existing coal-, biomass-, and oil-fired boilers smaller than 10MMBtu/hr will be subject to a biannual routine maintenance requirement in lieu of numeric emissions limits, with less frequent maintenance requirements for certain subcategories of boilers, such as seasonal and other limited-use boilers.

Due to the cost of complying with the boiler MACT requirements, which the National Association of Manufacturers estimates could be as much as $14 billion, it is anticipated that the boiler rules will cause many facilities to switch from coal to natural gas in order to avoid having to install potentially costly emissions-control devices.