The purpose of this article is to walk you through the Boiler MACT applicability, compliance dates and what regulations are applicable to your facility’s boiler and/or process heater. The full names of Boiler MACT and GACT as published in the Federal Register 40 CFR Part 63, is as follows: Boiler GACT (Generally Achievable Control Technologies), in short refers to the USEPA’s National Emission Standards for Hazardous Air Pollutants (NESHAP) for Area Source: Industrial, Commercial and Institutional Boilers. Boiler MACT (Maximum Achievable Control Technology) refers to the USEPA’s NESHAP for Major Sources: Industrial, Commercial, and Institutional Boilers and Process Heaters.
The Four Rules
To figure what rule applies to your facility, you first need to understand the Boiler MACT basic 4 rules. Boiler MACT is used in a generalized form to include the following specific rules:
- Boiler Area Source is a boiler in a facility (industrial, commercial or institutional) that its actual emissions of Hazardous Air Pollutants (HAP) are less the 10 tons per year of any single HAP or less than 25 tons per year of all HAPs combined. EPA allows Boiler Area Source facilities the use of Generally Available Control Technologies (GACT) or management practices to reduce emissions of hazardous air pollutant (as compared to Boiler MACT facilities explained later requiring stricter practices). Therefore, the Boiler Area Source is also referred to as Boiler GACT. See the Applicability Chart below to determine how your boiler is classified.
- The Boiler MACT rule applies to new and existing boilers and process heaters at major source emitters (commercial or institutional) of Hazardous Air Pollutants (HAPs). In the context of this rule, major sources are defined as having actual emissions of HAPs in excess of 10 tons per year of any single HAP or 25 tons per year of all HAPs combined. If your facility possesses a Title V or Part 70 (Major Source) Air Quality Permit, this does not necessarily mean that the Boiler MACT applies to you. A Title V Air Quality Permit signifies that actual emissions of at least one criteria pollutant (e.g. particulate matter, carbon monoxide, volatile organic compounds, etc.) exceed 100 tons per year for non-HAP pollutants or the 10/25 ton per year HAP thresholds previously stated. If permitted emissions of HAPs are below the major source thresholds, Boiler MACT does not apply to you; however, Boiler GACT may. See the Applicability Chart below to determine how your boiler is classified.
- Non-Hazardous Secondary Materials (NHSM) regulations identify which materials can be burned in Boiler MACT or GACT. In general, materials are considered NHSM and can be burned in boilers or process heater that are considered Boiler MACT or GACT if:
- The material is used as a fuel that remains within the control of the generator (whether at the site of generation or another site the generator has control over) and meets the legitimacy criteria. (for definition of legitimacy criteria, please see 40 CFR 241.3 (d)).
- The material is used as an ingredient in a manufacturing process (whether by the generator or outside the control of the generator) that meets the legitimacy criteria.
- The material has been sufficiently processed to produce a fuel or ingredient product that meets the legitimacy criteria.
- The material that has been determined through a case-by-case petition process not to have been discarded and to be indistinguishable in all relevant aspects from a fuel product.
- The material has been identified as a categorical non-waste fuel. Materials that have received a categorical non-waste determination from the EPA are:
- Scrap tires that are managed under established tire collection programs;
- Resinated wood;
- Coal refuse that has been recovered from legacy piles and processed in the same manner as currently-generated coal refuse;
- Dewatered pulp and paper sludges burned on-site at facilities that use a significant portion of materials as fuels, where such dewatered sludges are managed in a manner that preserves the meaningful heating value of the materials.
- Commercial and Industrial Solid Waste Incinerators (CISWI) unit is a device that is used to burn solid waste at a commercial or industrial facility. Examples of CISWI units include:
- Units designed to discard solid waste;
- Energy recovery units designed to recover heat that combust solid waste; and
- Waste burning kilns that combust solid waste in the manufacturing of a product.
- The CISWI rule covers 106 units in four CISWI subcategories:
- Incinerators;
- Energy recovery units;
- Waste-burning kilns; and,
- Small, remote incinerators.
-Energy recovery units (ERU) are further subcategorized into three subcategories: ERU liquids and gases, ERU biomass and ERU coal; for waste-burning kilns, there are two subcategories for CO emissions only, long kilns and preheater/precalciner.
-CISWI units must either comply with the emission limits in the final standards (i.e., install add-on controls to capture emissions) or use alternative waste disposal options, such as diverting waste to a landfill.
-See the Applicability Chart below to determine how your boiler is classified.
Boiler MACT and GACT apply to many industrial facilities with boilers and process heaters. NHSM and CISWI applies to only a small portion of industrial facilities. Therefore, the rest of this article will focus on Boiler MACT and GACT. See the applicability chart below to determine which of the four rules apply to your facility, or whether your facility is exempt from any of the four rules.

What is required?
Boiler MACT – You should have submitted the Initial Notification Report and Notification Compliance Status to the State and to the US EPA by 5/31/2013. Under the current Boiler MACT rule, all solid fuel and liquid fuel boilers and process heaters must meet emission limitations through performance tests and/or fuel analyses. There are a few exceptions, including limited-use boilers, boilers or process heaters associated with a source already subject to another rule, and boilers or process heaters used as emission control devices (e.g. thermal oxidizers). The emission limits in the rule are set quite low. It is conceivable that some older boilers currently in operation will require updated pollution control technologies. Additionally, all facilities must conduct regular tune-ups and perform a onetime boiler energy assessment of at least one boiler.
The tune-up requirement is not a simple boiler tune-up, as the rule establishes guidelines for the tune-up that are above and beyond what would normally be considered a “tune-up”. For existing units, the performance tests, tune-ups, and the onetime comprehensive energy assessment performed by a qualified energy assessor are required to be completed by January 31, 2016.
Boiler GACT – You should have submitted the Initial Notification Report and Notification of Compliance Status to the State and US EPA by January 20, 2014. Under the current Boiler GACT rule, all new or reconstructed boilers, and existing coal-fired and oil-fired boilers must meet emission limitations through performance tests and/or fuel analyses. The emission limits in the GACT rule are generally set lower than those in the MACT rule. Existing biomass boilers are not required to meet emission limitations. Additionally, much like the MACT rule, all affected facilities must conduct boiler tune-ups and perform a onetime boiler energy assessment of at least one boiler. The tune-up definition is the same as that under Boiler MACT. For existing units, the tune-up and the one time comprehensive energy assessment were required to be completed by March 21, 2014 by a qualified energy assessor. See the table of compliance deadline for existing units below. There are different dates for new constructed units and for facilities that took ownership or became Boiler MACT after any of those deadlines.

So What do I do Now?
- Determine if and how Boiler MACT is applicable to you using the applicable chart in this article.
- If you determine that your facility is Boiler GACT, the deadlines have passed. You should submit Initial Notification now and conduct tune-up and Energy Assessment as soon as possible.
- If you determine that your facility is Boiler MACT, the deadline for Initial Notification has passed. You should submit the notification now. You need to start planning, as soon as possible, for your boilers and/or process heaters to come in compliance with the rule. January 31, 2016, the compliance deadline, might seem far away, but it is not if you need to complete the following:
- Conduct an energy assessment
- Conduct a tune-up
- Boiler and process heater, not fueled by only natural gas, will require to meet more stringent emission limitations. Careful and timely planning is required to design and optimize now to meet those limitations more efficiently and least costly way.
- There is very little time to accomplish all of this by January 31, 2016.
- If you determine that there is a possibility that your boiler or process heater will be fueled by fuel that will not be classified NHSM or will not meet the Legitimacy Criteria after January 31, 2016, you need to start taking action immediately to address this problem.
- If you determine that the facility uses a CISWI, you need to start taking action to ensure that the unit is in compliance.