Boiler Compliance Requirements for Major Sources, 40 CFR 63, subpart DDDDD

On December 20, 2012, and and again on November 20, 2015, the U.S. Environmental Protection Agency (U.S. EPA) finalized changes to the rule (40 CFR Part 63, Subpart DDDDD) regulating existing and new industrial, commercial, and institutional boilers located at major source hazardous air pollutants (HAPs). A major source emits or has the potential to emit (PTE) more than or equal to 10 tons per year (tpy) of any single air toxic or more than or equal to 25 tpy of any combination of air toxics. The final rule applies to industrial, commercial, or institutional boilers or process heaters as defined in 40 CFR 63.7575, located at, or a part of, a major source of HAPs, except as specified in 40 CFR 63.7491.

Reporting Requirements

As specified in 40 CFR Part 63.9(b)(2), if startup of the affected source before January 31, 2013, an Initial Notification was required to be submitted by May 31, 2013.

As specified in 40 CFR Part 63.9(b)(4) and (5), if startup of the new or reconstructed affected source is on or after January 31, 2013, an Initial Notification is to be submitted to U.S. EPA Region 5 not later than 15 days after the actual date of startup of the affected source

Courtesy copies may be mailed to IDEM’s Office of Air Quality (OAQ), Compliance Branch.

Indiana Department of Environmental Management
Office of Air Quality Compliance Branch MC 61-53
100 North Senate Avenue IGCN 1003
Indianapolis, IN 46204-2251

Notification of Compliance Status and Compliance Certification Reports are to be submitted through the U.S. EPA’s Central Data Exchange (CDX).

Energy Assessments

New boilers are those having commenced construction or reconstruction after June 4, 2010.

Energy assessments provide owners and operators of boilers opportunities to reduce energy usage and increase efficiency of their systems. The U.S. EPA does not require owners and operators of boilers to implement recommendations made by the assessment. A one-time energy assessment was required by January 31, 2016 for existing boilers. New boilers are not subject to this requirement.

Energy Assessment Resources


The purpose in a boiler tune-up is to evaluate the boiler operating efficiency and make adjustments as needed. Existing boilers were required to conduct an initial tune-up by January 31, 2016 and subsequent tune-ups are due annually or up to every five (5) years depending on the fuel type and capacity.

New boilers must conduct a tune-up within 13, 25, or 61 months of start-up depending on their fuel source subcategory, if they are designated as limited use, and the boiler capacity.

What requirements do I have for my boiler?

Major source boilers are also subject to performance testing and a one-time energy assessment depending the age, capacity, and fuel-type category. If you are unsure whether you are subject to these requirements, select from either “New” or “Existing” from the fuel categories listed below for details on your specific requirements.

This list does not encompass all categories of boilers and fuel types. Please reference Table 1 and Table 2 of Subpart DDDDD for emission limits for Stokers, Sloped grate, Fluidized bed, Suspension burners, Dutch oven, Fuel cell units, and Hybrid suspension grate boilers

Has your fuel subcategory changed?

A revised notice of applicability, per 40 CFR 63.7545, must be submitted within 30 days of a change in fuel category. Natural gas or refinery gas (Gas 1 Fuel) boilers that have liquid fuel for back up maintain their category of Natural or refinery gas if they limit their usage of liquid fuel to 48 hours or less per year and use liquid fuel during a period of gas curtailment or supply interruption.

Notification Requirements for Periods of Gas Curtailment

If you use back-up fuels other than Gas 1 Fuels (natural gas or refinery gas), you must submit a notification of alternative fuel use within 48 hours of the declaration of each period of natural gas curtailment or supply interruption as per 40 CFR 63.7545(f).

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