USEPA Attempts To End “Once In Always In” Policy

Apr 18th, 2018 | By | Category: Featured Articles

In late January 2018 the U.S. Environmental Protection Agency (USEPA) issued an internal memorandum and in early February USEPA Administrator Scott Pruitt testified to Congress about his desire to rescind the “Once In Always In” (OIAI) policy for major sources under the federal National Emission Standards for Hazardous Air Pollutants (NESHAP) program. Under OIAI, a major source subject to Maximum Achievable Control Technology (MACT) standards is prohibited from reclassification, which would excuse it from these standards, even if the facility reduced air toxic emissions enough to become a minor source. The memo reverses this position.

This action is intended to reward major emission sources that have invested resources to significantly reduce hazardous air pollutant emissions to fall below the major source threshold. The USEPA plans to amend NESHAP text to codify this new policy beginning with a Federal Register posting. Legal challenges are expected.


Regulatory Background

The federal NESHAP program provides emission limits based on “maximum achievable control technology,” which is defined in the rule as fairly stringent requirements. MACT applies to sources that emit any of 187 listed hazardous air pollutants (“HAPs”) in more than 100 source categories. NESHAP covers two categories of sources, “major” and “area” sources. Major sources have the potential to emit at least 10 tons per year (tpy) of any listed HAP or 25 tpy of all HAPs. Any source that is not “major” is treated as an “area” source. Most MACT standards only apply to major sources; area sources are exempt. However, MACT standards for some source categories apply to both major and areas sources.

Given this, it is possible for a facility to accept federally-enforceable emission limits to become an area source (referred to as a “synthetic minor”) to avoid installing expensive MACT-compliant technology and also avoid significant recordkeeping and reporting requirements. This can be achieved potentially with air pollution control strategies that are less stringent than MACT or by reducing hours of operation. The USEPA in the early 1990s established a policy that a facility can become a synthetic minor, but only by doing so before a MACT standard becomes effective. One cannot avoid the standard after the MACT standard goes into effect, leading to the OIAI policy.

Major environmental groups strongly oppose rescinding OIAI stating that stringent requirements for sources of HAPs are needed even if actual HAP emissions drop below the major thresholds. These groups maintain that OIAI provides a means of addressing the potential public health impacts associated with HAP emissions and also makes the MACT standard easier to enforce if a plant were to “backslide” in the future and once again become a major source of HAP emissions.

The USEPA, on the other hand, justified the new policy on the grounds that Congress in the Clean Air Act provided no language pertaining to the reclassification of major sources to area ones. Their new guidance memo wishes to inject “plain language” that a facility would switch from a major source of HAPs to an area source when an enforceable limit on the potential to emit HAPs below the “10/25” thresholds is achieved and approved.


Benefits of Changing “Once In Always In”

The USEPA believes its new policy ending OIAI will have several outcomes including:

  • Result in “meaningful incentives” for facilities to undertake projects that will reduce HAP emissions below major source thresholds.
  • Eliminate a “punishment” imposed on facilities whose HAP emissions have dropped below the major source threshold but are nonetheless required to meet the onerous regulatory requirements that apply to major sources.
  • Remove the burden for facilities whose potential to emit (based on unrestricted operation) is above the major source threshold, but whose actual emissions are significantly below it. Facilities that were unsure how to limit their operation to achieve federally-enforceable limits often chose to proactively enter a given MACT program. But for those whose subsequent operation confirmed that actual HAP emissions were truly well below the major threshold, it was too late for relief – once in, always in.


Next Steps in the OIAI Debate

While this is an article of facts and background, I do wish to provide a compromise position that I think would achieve the goals of both sides of this debate. New York State has a policy that any facility wishing to permit itself just below any applicable threshold (even for non-HAP compounds) must be limited to 10% below the threshold to account for any unexpected or accidental release (even if these events were to occur, the facility would likely still be below the threshold). Applied to this situation, if a facility can commit and abide by permit limits of 9 tpy for any HAP and 22.5 tpy of all HAPs and maintain this for a set time, say, two years, then it could be reclassified to an area source, and all MACT requirements would be removed.

While there are likely to be legal battles concerning the elimination of OIAI, facilities that are regulated as major HAP sources should review their current emissions inventories to see if they have fallen below the major source thresholds or are close enough to make the reduction to below the threshold technically and economically feasible. It may be to the facility’s advantage to document that its actual emissions are below the major threshold or implement the changes that will ensure this. To codify this, a facility would need to modify its Title V Air Permit to remove the MACT standard as an applicable rule and in so doing, remove or lessen control, recordkeeping, and reporting requirements. Some states, which may be resistant to this change, may not implement any such changes until all court proceedings are completed. Also, some have “anti-backsliding” provisions that may prevent the loosening of existing restrictions. Such facilities should retain the proper technical and legal experts as they are proceeding.



Please note that this is a technical, not a legal, assessment of the change in federal OIAI policy. Speak to appropriate legal counsel before making any decisions on this or related matters.


About the Author

Marc Karell, P.E., CEM, EBCP, is president of Climate Change & Environmental Services, LLC, a technical consulting firm that has the technical experts to help facilities assess whether their current air emissions exceed or are below any major applicability threshold. CCES can provide advice on the most cost-effective ways to reduce HAP (and non-HAP) emissions for a variety of processes. CCES also provides assistance in developing robust sustainability, climate change, and energy saving programs. Specialties include energy audits, retro-commissioning, sustainability, smart engineering, problem solving, climate change, greenhouse gas emission inventories (carbon footprinting), air and hazardous air pollutant emissions inventories, regulatory compliance assessments (audits), strategies for compliance or emission reduction, and design of air pollution control equipment.

Photograph: City in the Dusk Clouds by jihong5965.


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