September 14, 2021

Draft Guidance on Subpart BB and CC Applicability

In 2017, EPA’s Office of Enforcement and Compliance Assurance launched its national compliance initiative to reduce organic emissions from equipment managing hazardous waste. This initiative renewed the focus on compliance with RCRA’s air emission standards found in Parts 264/265 Subparts AA, BB, and CC. Though Subparts BB and CC are more than 25 years old, there is still confusion on their scope. To clarify the issue, EPA released a draft document for public comment on August 4, 2021. Comments and questions may be submitted via email to until October 3, 2021.

Subparts BB and CC, though similar in goal, regulate different equipment. Subpart BB establishes organic air emission controls for equipment leaks—achieved by regulating ancillary equipment such as valves and pressure relief devices. Subpart CC establishes controls for tanks, containers, and surface impoundments and regulates the closure devices of those units. EPA acknowledges the term “closure device”, which includes both conservation vents and safety devices, is similar to certain equipment regulated by Subpart BB. The agency uses an example of a hazardous waste tank with level 1 controls to demonstrate when Subpart BB vs. Subpart CC applies. In essence, Subpart CC applies when the closure device is specifically associated with the roof, or cover, of the tank. Other equipment not satisfying the definition of “closure device” (e.g., a valve on the side of a tank) is subject to Subpart BB.


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