Proposed Amendments to 40 CFR 63 Subpart DDDDD Looming
The final rule for National Emission Standards for Hazardous Air Pollutants for Major Sources: Industrial, Commercial, and Institutional Boilers and Process Heaters: Amendments, also knows as the Boiler MACT, are due shortly.
The EPA is proposed 34 (of 90) emission limits for new and existing sources. Courts ruled that the EPA must include all boilers subcaterogized using the 10% threshold for category-defining fuel type in the MACT floor analysis. Previously the EPA excluded units utilizing less than 90% from the MACT floor analysis.
Of these 34 emission limits, 28 of the limits would become more stringent and six of the limits would become less stringent.
EPA is also proposing that facilities would have up to 3 years after the effective date of the final rule to demonstrate compliance with these revised emission limits.
The comment period on the proposed regulation ended October 23, 2020. Comments have been posted to the docket and can be found here.
A Brief History of Boiler MACT:
On January 31, 2013, the EPA promulgated amendments to the National Emission Standards for Hazardous Air Pollutants for Major Source: Industrial, Commercial, and Institutional Boilers and Process Heaters. Environmental groups and industry filed for judicial review of the amended final rule. The court issued its decision on July 29, 2016, vacating the maximum achievable control technology (MACT) standards for all subcategories that were affected by the EPA’s exclusion of certain sources from consideration when setting the standards. The court also remanded the carbon monoxide standard to the EPA to adequately explain how carbon monoxide acts as a reasonable surrogate for organic hazardous air pollutants. On September 12, 2016, the EPA petitioned the court asking that the MACT standards be remanded without vacatur. On December 23, 2016, the court granted the EPA’s request. In November 2015, the EPA finalized its decision on certain other issues for which it granted reconsideration. Environmental groups filed a petition for judicial review of the reconsideration action. The court issued its decision on March 16, 2018, remanding for further explanation the revised 130 parts per million carbon monoxide emission limits. This final rule will address the issues that were remanded in the two court decisions.
The proposed amendments can be found on the EPA.gov website here.
The U.S. EPA signed an amendment to the rule on February 28, 2022 that removes the stay of the formaldehyde limit for lean premix and diffusion flame gas-fired units that were constructed or reconstructed after January 14, 2003.