The Boiler MACT is Back!

Almost two years after EPA issued the flawed Boiler MACT for major and area sources and a year after the proposed revisions were announced, the revised rule has been published. Conversely, the revised rule provides both additional complexities while relaxing standards for certain types of sources.

Brief History

In March, 2011, EPA published National Emissions Standards for Hazardous Air Pollutants (NESHAPS) for major sources and area sources of industrial, commercial, and institutional boilers and process heaters (the Boiler MACT). A major source emits or has the potential to emit 10 tons per year of any single HAP or 25 TPY of any combination of HAP. An area source is any source that is not a major source. Recognizing how flawed the rules were, EPA announced it was reconsidering parts of the rule on the same day it published the final Boiler MACT.

EPA also sought to delay the effective date of the Boiler MACT, until “the proceedings for judicial review of these rules are completed or the EPA completes its reconsideration of the rules, whichever is earlier.” 76 FR 28662 (May 18, 2011). However, the district court struck down the attempted delay. Thereafter, EPA issued a series of No Action Assurance Letters in which EPA announced it would not enforce certain parts of the rule.

A proposed rule was published on December 23, 2011. EPA has now taken final action on the reconsideration.

The Major Source Rule

EPA revised certain categories of boilers and process heaters based on the design of the combustion equipment. Now, there are 19 subcategories, most of which have numeric emission limits for carbon monoxide, hydrogen chloride, mercury, and particulate matter. Many of the emission limits were changed due to new data, corrections to old data, and inventory changes. Thirty percent of the emission limits are more stringent, fifty percent are less stringent, and twenty percent remained the same.

There are 14,136 major source boilers at 1,700 facilities. All will be required to conduct periodic tune-up but only about twelve per cent will be required to meet the numeric emission limits. Those boilers will be required to conduct performance tests. For existing sources, the compliance date is January 31, 2016 and January 31, 2013 or upon start-up for new sources.

EPA estimated that, when compared to the March 2011 rule, the revised rule had slightly lower total capital expenditures of $4.7 billion but had slightly higher total annual costs at $1.5 billion per year. The costs include control devices, work practices, testing, and monitoring. 78 Fed.Reg. 7155 (Jan. 31, 2013). These figures include boilers at 72 major source facilities that were not included in the previous boiler inventory. When the costs impact for these newly discovered boilers is discounted, the estimated incremental costs impacts are $1 billion in capital expenditures and $130 million in annual costs less than the costs estimated for the March 2011 rule.

The Area Source Rule

As with the major source rule, EPA expanded the categories of boilers and process heaters based on the design of the combustion equipment. Now, in addition to coal, biomass, and oil, EPA added seasonal boilers, limited-use boilers, oil-fired boilers with low heat input, and certain boilers using a continuous oxygen trim system. Seasonally operated boilers are biomass or oil-fired boilers that undergo a shut-down for 210 consecutive days each 12-month period.

There are 183,000 area source boilers at 92,000 facilities. Initial notifications for existing affected boilers are now due on January 20, 2014. New and existing coal-fired boilers and larger biomass and oil-fired boilers must meet specified emission limits. They must also minimize startup and shutdown periods, conduct biennial initial tune-ups, and, for existing boilers, conduct an initial tune-up. The new subcategories (e.g., the seasonal boilers) generally must conduct a tune-up every five years and, for existing boilers, conduct an initial tune-up.

For existing sources, the compliance date is March 21, 2014. New sources (defined as those that began operations after June 4, 2010) that began before May 20, 2011 must comply before May 20, 2011. New sources that began after May 20, 2011 must comply upon start-up.

EPA made clear that “this final rule will not affect the estimated emission reductions, control costs or the benefits of the rule.” 78 Fed.Reg. 7489 (Feb. 1, 2013). The preamble and the Regulatory Impact Analysis for the March 2011 rule estimated that 97 pounds of mercury, 320 tons of other metals, 2,500 tons or particulate matter would be reduced at a cost of $525 million. However, the monetized health benefits would be between $190 million and $470 million. Thus, the costs of the rule outweigh the monetized benefits.


EPA’s revision is even more complex than the original rule. It adds multiple subcategories, each with a variety of emission limits, work practices standards, testing and monitoring requirements, and compliance schedules. On the other hand, it does makes compliance easier for certain area sources, which are the bulk of the boilers and which are mainly located at smaller facilities that can least afford expensive testing or monitoring. Nevertheless, this chapter of the Boiler MACT saga has been written, but additional chapters are forthcoming as the revised rule will surely be litigated by those who commented and did not obtain the relief they wanted.

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