U.S. EPA Clarifies “Modification” as it Relates to NSPS Subpart XXa

The United States Environmental Protection Agency (U.S. EPA) has clarified what constitutes a “modification” in response to questions received regarding the Standards of Performance for Bulk Gasoline Terminals that Commenced Construction, Modification, or Reconstruction After June 10, 2022 under 40 Code of Federal Regulations (CFR) part 60, subpart XXa (NSPS XXa). The industry and its partners had voiced concerns about the potential that routine activities could be considered modifications and trigger applicability of NSPS XXa.

The final rule was published on May 8, 2024, and became effective July 8, 2024. If an existing facility makes a change that meets the definition of a modification following the effective date of NSPS XXa, it is required to meet the requirements of NSPS XXa. Definitions for terms used in 40 CFR part 60 are found in subpart A under 40 CFR §60.2,  and the term “modification” is defined as “any physical change in, or change in the method of operation of, an existing facility which increases the amount of any air pollutant (to which a standard applies) emitted into the atmosphere by that facility or which results in the emission of any air pollutant (to which a standard applies) into the atmosphere not previously emitted.” Modification is discussed further in 40 CFR 60.14, which excludes items such as routine maintenance, repair, and replacement of equipment in the source category, increases in production without a capital expenditure, an increase in hours of operation, and the relocation or change in ownership of an existing facility.

U.S. EPA’s clarification states that minor equipment changes that do not result in an increase in the emission rate of volatile organic compounds (VOC) or that are considered routine maintenance, repair, and replacement of equipment are not considered modifications under 40 CFR 60.14. Examples of changes that U.S. EPA would not considered modifications under NSPS XXa include: adding piping, valves, or pumps that are needed to improve emissions control or for operational flexibility that are not anticipated to increase site/facility VOC emissions; temporary installation of piping and equipment needed to perform maintenance or repair activities for storage vessels, loading racks, and vapor collection and processing systems; and/or addition of piping components needed for safety or mechanical integrity purposes (e.g., low point bleeds, sampling, pressure relief, and isolation valves).

U.S. EPA also notes that although NSPS XXa does not currently contain specific provisions that prevent minor equipment changes from being considered modifications (e.g., if no capital expenditure is made), they recently granted reconsideration on this issue. Stay tuned for updates on changes and clarifications to this and other U.S. EPA rules. If you need help evaluating a project for regulatory applicability, please reach out to Troy Gayer or your ALL4 project manager.