Air Pollution Control Equipment Services, Emissions, Policy & Regulations

Once-In-Always-In is OUT

Issue 5 and Volume 122.

The January 25, 2018 EPA memo on “Reclassification of Major Sources as Area Sources” significantly changes an Environmental Protection Agency (EPA) policy in place since 1995. The EPA and State Agencies have been operating on a Once-In-Always-In (OIAI) policy for emissions of hazardous air pollutants (HAPs) for the past 23 years.

OIAI established that once a source crossed the major-source thresholds for HAPs (10 tons per year for a single HAP or 25 tons per year for combined HAPs) and was required to comply with the Maximum Achievable Control Technology (MACT) standards, it would never be able to become an area source (i.e. a minor source) for HAPs by reducing the facilities potential to emit for HAPs. The EPA was concerned that by allowing a facility to take an enforceable limit for their PTE and to become an area source for HAPs, sources would then limit their potential to emit via control technologies that were less-stringent than the MACT standard. The EPA regulators were thought this would cause an increase in HAP emissions and the emission reductions mandated by congress would not be achieved.

In January of 2018, the EPA issued updated guidance that restored the “plain language” reading the statute and rescinded the OIAI policy across the country. Today, a facility or source at any time can take an enforceable limit in a permit to reduce the PTE below the 10/25 tpy for single/combined HAPs and be reclassified as an area source that is no longer required to meet the facility’s MACT limitations or the industry-specific NESHAP limits.

This reclassification helps many facilities that have lowered their HAP emissions due to evolution in process and throughput. For example, a decade ago, a facility that operates several painting booths projected that their 12-month rolling emissions of toluene would exceeded the 10 tpy threshold. Because of this projection, the facility was classified as a major HAP sources and was then subject to the industry-specific NESHAP standard, as a part of the MACT determination. The facility’s 12-month rolling emissions of toluene only exceeded the single HAP threshold for 3 months. Since this time, the facility has begun using a reformulated paint with a lower HAP content and has reduced production at that site. The actual HAPs for the source is now around 1 tpy toluene. Under OIAI, they were not able to get an enforceable permit limit in order to be released from the NESHAP. Since OIAI has been revoked, the facility can now obtain a permit limitation for 10/25 tpy for a single/combined HAP, eliminating the recording keeping and documentation requirements for the facility.

“If your facility is classified as a major source of HAPs, but your actual emissions are below 10/25 tpy, you should re-evaluate your current permits to see if your facility could benefit from this change in policy.”

Similarly, converting fuels can cause operational changes that can reduce the emission of HAPs, for example a coal-fired boiler that was repowered to burn only natural gas. Combusting coal, the boiler was a major HAP source and subject to MACT and NESHAP standards. After switching to natural gas, HAP emissions are well below the HAP tpy thresholds. Under this new policy, the facility can request a site-wide enforceable limit of 10/25 tpy for single/combined HAPs. This will remove the NESHAP compliance requirements the facility was required to maintain that were only relevant when combusting coal.

Environmental groups have argued that HAP emissions will increase now that OIAI has been revoked. However, OIAI never prevented an area HAP source from increasing the source PTE to become a major source, and facilities that are redefined will be legally required to maintain HAP emissions at or below thresholds for area sources. On the other hand, industry claimed that OIAI policy discouraged facilities from voluntarily making changes to their processes that would reduce HAP emissions (e.g. installing emission controls, switching to a solvent with a reduced HAP content, implementing innovative technologies or processes, etc.), and it is probable that many facilities will now be applying for construction or operating permits that incorporate many of these changes, while reducing the recordkeeping requirements for the sites.

If your facility is classified as a major source of HAPs, but your actual emissions are below 10/25 tpy, you should re-evaluate your current permits to see if your facility could benefit from this change in policy.