Final Major Source Boiler MACT: (Some) Good Things Come to Those Who Waited!

In general, only 30% of the emission limits in the final rule are more stringent than the March 2011 final rule, with the rest being less stringent or the same.  Of the five regulated pollutants, the pollutant that experienced the greatest emission limit reduction was HCl for existing subcategories and Hg for new subcategories. However, compared to the December 2011 proposed version of the rule, all pollutants experienced at least three reductions to emission limits for existing and new subcategories. The final rule establishes an alternative emission standard for CO through use of a facility’s continuous emission monitoring system (CEMS), if available.  The alternative standard is based on either a 30-day or 10-day rolling average depending on the subcategory.   The final rule maintained emission limits based on an output standard as an option for facilities.  

The Major Source rule provides revised work practice standards for periods of startup and shutdown. Facilities must comply with all applicable emissions and operating limits at all times the unit is in operation except for periods that meet the definition of startup and shutdown. The work practice standard for periods of startup and shutdown includes operating all CEMS during startup and shutdown, utilizing one or more listed clean fuels during startup, engaging certain control devices during startup once certain fuels begin to be fired, and engaging those same control devices during shutdown while those same fuels are fired.  Facilities must keep records concerning the date, duration, and fuel usage during startup and shutdown. The revised definitions of startup and shutdown periods are as follows:

• Startup “means either the first-ever firing of fuel in a boiler or process heater for the purpose of supplying steam or heat for heating and/or producing electricity, or for any other purpose, or the firing of fuel in a boiler or process heater after a shutdown event for any purpose.  Startup ends when any of the steam or heat from the boiler or process heater is supplied for heating and/or producing electricity, or for any other purpose.” 

• Shutdown “means the cessation of operation of a boiler or process heater for any purpose.  Shutdown begins either when none of the steam and heat from the boiler or process heater is supplied for heating and/or producing electricity, or for any other purpose, or at the point of no fuel being fired in the boiler or process heater, whichever is earlier.  Shutdown ends when there is both no steam or heat being supplied and no fuel being fired in the boiler or process heater.”

Initial compliance with all applicable emission limits must be demonstrated through performance testing for new and existing boilers and process heaters.  The final rule adds the requirement to conduct initial and annual stack tests to determine compliance with the TSM emission limits using U.S. EPA Method 29 for those subcategories with alternate TSM limits.  The final rule also adds some flexibility to the annual test requirements.  If a facility’s performance tests for a given pollutant for at least two consecutive years show that the emissions are at or below 75 percent of the emission limit for the pollutant, and there are no changes in the operation of the individual boiler or process heater or air pollution control equipment that could increase emissions, the facility has the option to conduct performance tests for the pollutant every third year. If this option is chosen, the performance test must be conducted no more than 37 months after the previous performance test.

Regarding continuous compliance requirements, the final rule removes the requirement for units combusting biomass with heat input capacities of 250 MMBtu/hr or greater to use CEMS for measuring PM emissions. The final rule requires units combusting solid fossil fuel or heavy liquid fuel with heat input capacities of 250 MMBtu/hr or greater to use PM continuous parameter monitoring systems (CPMS), or to use PM CEMS as an alternative. The final rule also includes an alternative method of demonstrating compliance with the HCl emission limit by utilizing a sulfur dioxide (SO₂) CEMS and an acid-gas control technology (e.g., wet scrubber).

Fuel sampling requirements were revised for gaseous fuel-fired units that elect to demonstrate that the unit meets the specification for mercury for the “unit designed to burn gas 1” subcategory.  If the mercury constituents are measured to be equal to or less than 50 percent of the mercury specification, then no further sampling is required.  If the constituents are measured to be 50 or up to 75 percent of the specification, then semi-annual sampling is required.  If the constituents measure over 75 percent of the specification, then monthly sampling is required.

Gas fired units or small boilers (less than 10 MMBtu/hr heat input) are subject only to work practice standards.  All boilers, regardless of the subcategory, are subject to periodic tune-up work practices for dioxin/furan emissions. Additionally, certain sources will be subject to work practice standards that will include the following requirements:

• Tune-ups:  The final rule requires a tune-up, but at a revised frequency based on public comments.  The burner inspection requirement has been relaxed to allow units that sell electricity to complete the burner and air-to-fuel ratio inspections at the first outage, which is not necessarily annually, but not to exceed 36 months before an inspection is completed.  Therefore, a unit doesn’t have to be taken offline for the sole purpose of completing the annual tune-up.  Similarly, where tune-ups require entry into a storage vessel or process equipment, the requirement has been relaxed so that the tune-up is only required during the next planned entry into the vessel.  Also, boilers or process heaters that operate a continuous oxygen trim system require a tune-up every five (5) years as opposed to annually.
• Energy Assessment:  If the facility completed an energy assessment on or after January 1, 2008, then the requirement has been satisfied pursuant to the final rule, given that the assessment meets the requirements in Table 3 of the final rule.  Also, a facility that operates under an energy management program compatible with ISO 50001 that includes the affected units satisfies the energy assessment requirement.

Existing sources must be in compliance within three (3) years from the date of publication of the final rule in the Federal Register (approximately early 2016).  New sources (which remain defined as those that began operating on or after June 4, 2010) must be in compliance from the date of publication of the final rule in the Federal Register or upon startup, whichever is later.  Under certain circumstances, U.S. EPA is allowing facilities to apply for a one (1) year extension if such time is needed for the installation of controls.  The authority to approve the extension lies with the facilities’ permitting agency.  Additionally, initial notification will be due within 120 days from publication of the final rule in the Federal Register, likely in late-Spring or early-Summer.  A Notification of Compliance Status (NOCS) must be submitted within 60 days of completing all applicable performance tests and/or other initial compliance demonstrations.

Affected facilities must determine (or confirm) what subcategory their combustion source falls under, and thus determine the set of emission limits and requirements each source must comply with.  Although U.S. EPA relaxed some of the previous requirements (e.g., the requirement of a PM CEMS, some of the emission limits, and startup and shutdown exclusions), facilities still have a lot of work ahead of them to demonstrate compliance with all of the initial performance testing, required tune-ups and energy assessment recordkeeping, and installation of add-on control devices, if necessary.  In many cases, modifications to existing boilers will require permitting, which can take years by itself, from planning the modifications, developing the permit application, time for agency review of the application, reviewing the draft permit, and time for public comment. Therefore, the time to start preparing a compliance strategy is now.

The pre-publication version of the final rule can be found here.