April 15, 2026

New Standards Proposed for Wood-Burning Air Curtain Incinerators

On March 20, 2026, EPA proposed two separate and distinct actions under the solid waste combustion provisions of CAA Section 129 [42 U.S.C. Section 7429]. [91 FR 13543] Comments on the proposed actions may be submitted through May 4, 2026 via Docket ID No. EPA-HQ-OAR-2025-0068.

The agency proposes consolidating the existing provisions for air curtain incinerators (ACIs) that only burn wood wastes, yard wastes, and clean lumber into a new NSPS subpart. Specifically, the reporting, recordkeeping, monitoring, and opacity provisions associated with large municipal waste combustors (LMWCs), small municipal waste combustors (SMWCs), commercial and industrial solid waste incinerators (CISWIs), and other solid waste incinerators (OSWIs) would be consolidated. EPA would also remove the permitting requirement for these types of ACIs that are not located at major sources or subject to federal permitting requirements. ACIs currently subject to OSWI or LMWC rules that have already been amended to remove such permitting requirements are not subject to the proposal.

EPA argues a new Part 60, Subpart Ca is necessary to consolidate the wood burning ACIs requirements because such units are not “solid waste incineration units” as defined in CAA Section 129(g)(1)(C) [42 U.S.C. Section 7429(g)(1)(C)]. Consequently, these units are not subject to Title V permitting under CAA Section 129(e) [42 U.S.C. Section 7429(e)] or 40 CFR §70.3(b)(1) and should be regulated separately. An ACI would be defined as an “incinerator that operates by forcefully projecting a curtain of air across an open, integrated combustion (fire box) or open pit or trench (trench burner) in which combustion occurs.”

EPA proposes to include in the CISWI rule subparts provisions for the temporary use of CISWI units to combust debris from a qualifying disaster or emergency on a temporary basis without complying with CAA Section 129 [42 U.S.C. Section 7429] requirements that would otherwise apply to CISWI units for the combustion of commercial and industrial waste during normal operations. These additions would align the CISWI subparts with existing OSWI provisions that allow the temporary use of OSWI units to combust debris from disasters or emergencies.

This second action would permanently codify a previous interim final rule (IFR) that created a temporary-use exemption for certain CISWIs regulated under Part 60, Subparts CCCC and DDDD, and Part 62, Subpart III. The IFR had allowed certain incinerators to bypass otherwise applicable regulatory requirements when combusting nonhazardous disaster debris in specific emergency circumstances. While deemed necessary for the 2025 hurricane and wildfire season [90 FR 41508], those circumstances have passed, and the agency rescinded those temporary provisions on March 19, 2026. [91 FR 13225]

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