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Proposed Boiler MACT Reconsiderations Released

Posted: December 3rd, 2014

Author: All4 Staff 

U.S. EPA has released the proposed reconsideration of the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Major Sources: Industrial, Commercial, and Institutional Boilers and Process Heaters (40 CFR Part 63, Subpart DDDDD) and of the NESHAP for Area Sources: Industrial, Commercial, and Institutional Boilers (40 CFR Part 63, Subpart JJJJJJ).  The pre-publication versions of the Major and Area Source rules are available on U.S. EPA’s Air Toxics website.  The reconsiderations were prompted by submittals from industry, environmental, and state and local regulatory agencies in 2013 that requested U.S. EPA to revise parts of the two (2) rules.  In response to the petitions, U.S. EPA identified three (3) items for which comments are requested related to the maximum achievable control technology (MACT) standards contained in Subpart DDDDD (Major Source Boiler MACT rule) and five (5) items for which comments are requested related to Subpart JJJJJJ (Area Source Boiler MACT rule).  In addition to the request for comments, U.S. EPA also made technical corrections, fixed typographical errors, and clarified the intent for various requirements in both rules.  Comments will be accepted for 45 days after publication of the proposed rules in the Federal Register, or 30 days after a public hearing if one is held, which is likely.

U.S. EPA has also released the proposed reconsideration of the Commercial and Industrial Solid Waste Incineration (CISWI) rules, which can be found here.  Stay tuned for a separate blog post addressing the CISWI rules.

The proposed changes for which U.S. EPA is requesting comment for the Major and Area Source Boiler MACT rules are summarized below.

Subpart DDDDD: Major Source Boiler MACT Rule

The three (3) areas for which U.S. EPA is requesting comment related to Subpart DDDDD are:

  1. Current and revised definitions that affect the startup and shutdown provisions.
  2. An updated carbon monoxide (CO) emission limit.
  3. Aspects of the use of particulate matter (PM) continuous parameter monitoring system (CPMS).

A brief summary of the parts of the rules open for comment are provided in the following paragraphs.

  1. Startup and Shutdown Provisions: U.S. EPA is requesting comment on the original January 2013 format of the startup and shutdown provisions and on proposed alternative provisions for startup and shutdown periods. As part of the alternative provisions, revised definitions that address the terms “startup,” “shutdown,” and “useful thermal energy” are proposed.  The revised definitions are reflected in a proposed alternate work practice standard that would apply during periods of startup and shutdown.  Finally, U.S. EPA is requesting comment on the recordkeeping requirements during startup periods.  Specifically, an alternative definition of startup is proposed as a compliance option, which closely aligns with the recently finalized Mercury and Air Toxics Standards (MATS).  Under the alternative definition, startup means:

    The period in which operation of a boiler or process heater is initiated for any purpose. Startup begins with either the firing of fuel in a boiler or process heater for the purpose of supplying useful thermal energy (such as steam or heat) for heating, cooling or process purposes, or producing electricity (other than the first-ever firing of fuel in a boiler or process heater following construction of the boiler or process heater), or the firing of fuel in a boiler or process heater for any purpose after a shutdown event. Startup ends four hours after when the boiler or process heater makes useful thermal energy (such as heat or steam) for heating, cooling, or process purposes, or generates electricity, whichever is earlier.

  2. Updated CO Emission Limit: The petitions to the January 2013 rule included a request to revise the minimum level of 130 parts per million by volume, dry basis (ppmvd) at 3 percent oxygen (% O2) CO emission limit for certain subcategories of boilers.  U.S. EPA believes that the CO emission limit is appropriate but also agrees that the public lacked the opportunity to comment on the emission limit.  Therefore, U.S. EPA is accepting comment and data regarding the 130 ppm CO emission limit to assess whether an alternate limit is justified or if work practice standards could be more appropriate.
  3. Use of PM CPMS: Boilers that combust solid fossil fuel or heavy liquid fuel and that have a heat input of 250 million British thermal units per hour (MMBtu/hr) or greater are required to operate a particulate matter (PM) Continuous Parametric Monitoring System (CPMS).  U.S. EPA established an allowable number of excursions from operating parameter limits for the PM CPMS before an excursion in a parameter limit is presumed to be an emission violation.  In response to comments by the regulated community, U.S. EPA is accepting detailed information from entities that might support a revision to how CPMS excursions should be evaluated.

In addition to the three (3) specific requests for comments, the affirmative defense provisions were removed based on the D.C. Circuit Court’s April 2014 ruling which stated that the Clean Air Act Section 112 rules (i.e., the NESHAPs at 40 CFR Part 63) should apply at all times.  The removal of the affirmative defense provisions means that civil penalties can be assessed if an emission limitation is exceeded during a malfunction event.

Subpart JJJJJJ: Area Source Boiler MACT Rule

Sources subject to Subpart JJJJJJ have the opportunity to provide comment on five (5) issues related to the area source requirements:

  1. Startup and Shutdown Provisions: U.S. EPA is proposing revisions to the definition of startup and shutdown as well as accepting comment on the current regulatory definitions of these two (2) terms. These definitions are consistent with those in Subpart DDDDD.  U.S. EPA is also proposing “useful thermal energy” as a new term in conjunction with the startup and shutdown provisions.
  2. Alternate PM Standards for New Boilers Firing Low Sulfur Oil: U.S. EPA is requesting comment related to an exemption for boilers that combust ultra-low sulfur oil to meet a PM emission limit.  In addition, sources firing ultra-low sulfur oil would not be required to conduct initial performance testing to demonstrate compliance with PM emissions limits.
  3. Establishment of Limited-Use Boiler Subcategory: Environmental groups petitioned U.S. EPA to reconsider the establishment of a limited-use boiler subcategory and require that these limited-use boilers be only subject to tune-up requirements.  Environmental groups felt that emission limits and performance testing requirements should be considered for the limited-use boiler subcategory.  U.S. EPA agreed that the petition was valid; however, U.S. EPA believes that its regulatory approach is adequate.
  4. Elimination of PM Performance Testing for Select Sources: Environmental groups petitioned U.S. EPA to reconsider exempting sources demonstrating very low PM performance test results in their emission tests from further testing.  As a result of the petition, U.S. EPA is requesting comments and information on PM variability during emission testing. 
  5. Elimination of Fuel Sampling for Select Sources: Environmental groups petitioned U.S. EPA concerning the fuel sampling for mercury (Hg) and the decision to exempt sources from fuel sampling based on a single sample showing low Hg levels.  U.S. EPA is requesting comment and data on the variability of Hg in coal as well as alternate Hg fuel sampling programs that include a single annual sampling event requirement for sources demonstrating low Hg levels.  For Hg levels that are greater than half of the Hg emission limits, quarterly fuel sampling would be required.

Like Subpart DDDDD, the affirmative defense provisions contained in §63.11226 were removed based on the D.C. Circuit Court’s April 2014 ruling. 

The revisions presented here are not intended to be comprehensive, but rather highlight the changes that are most likely to impact regulated entities.  

Want to learn even more about Boiler MACT and find out if you’re “on track”?  Check out our Major Source Boiler MACT Compliance Checklist and our 4 Rules/Boiler MACT Initiative Page for additional resources.


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