US EPA Withdraws "Once In, Always In" Policy


In a guidance memorandum dated January 25, 2018, US EPA withdrew its “once in, always in” policy for the classification of “major sources” of hazardous air pollutants (HAP) under section 112 of the Clean Air Act. According to Bill Wehrum, assistant administrator of EPA’s Office of Air and Radiation: “this guidance is based on a plain language reading of the statute that is in line with EPA’s guidance for other provisions of the Clean Air Act. It will reduce regulatory burden for industries and the states, while continuing to ensure stringent and effective controls on hazardous air pollutants.”

“Major sources” of HAP are defined as any stationary source or group of stationary sources (i.e., facilities or plants) with the potential to emit 10 tons/yr or more of an individual HAP or 25 tons/yr or more of any combination of HAP. Major sources of HAP are required to obtain a Title V air permit and maybe subject to maximum achievable control technology (MACT) standards for major sources. Facilities that are not major sources of HAP are “area sources” of HAP. US EPA has adopted approximately 134 MACT standards found in 40 CFR Part 63. There are currently 187 HAPs listed in section 112(b) of the Clean Air Act.

Historically, under US EPA’s “once in, always in” policy, major sources of HAP were able to obtain synthetic minor permit limits to cap facility-wide potential emissions of HAP below the 10 and 25 ton/yr major source trigger levels so long as those permit restrictions were obtained prior to the major source MACT standard compliance date. Facilities that failed to obtain synthetic minor permit limits prior to the MACT standard compliance date remain always subject to the major source MACT standard(s). Facilities that downsized due to economic or other factors, reformulated to non-HAP containing materials or installed add-on pollution control equipment after the MACT standard compliance date could not drop out of the major source MACT standards.

Typically, the monitoring, recordkeeping, reporting and testing requirements of major source MACT standards are very burdensome and expensive to comply with. It is often advantageous for facilities with actual HAP emissions less than the major sour trigger levels, but potential emission greater than the major source trigger levels to obtain facility-wide synthetic minor permit limits to avoid major source MACT standards. It may also be advantageous for facilities to install add-on pollution control equipment to avoid major source MACT standards. Under this new guidance, facilities maybe able to opt-out of the major source MACT standards and Title V permitting requirements at any time.

US EPA anticipates that it will soon publish a Federal Register notice to take comments on adding regulatory text that will reflect their plain language reading of the statute. Expect this latest guidance to be contested in the courts.

If you have any questions, contact Ron Hansen at 614-794-3570 Ext. 21.

by Ron Hansen, Owner/Principal Consultant