EPA Proposed Rule on Air Curtain Incinerators and Disaster Debris Combustion

Content

ACTION:

Proposed rule; request for comment.

SUMMARY:

The U.S. Environmental Protection Agency (EPA) is proposing two separate and distinct actions under Clean Air Act (CAA) section
129. In the first action, the EPA proposes to consolidate the existing provisions governing air curtain incinerators (ACI)
that only burn wood wastes, yard wastes, and clean lumber into one new rule subpart. Specifically, we are proposing to consolidate
the opacity limitations and associated monitoring, recordkeeping, and reporting requirements that currently exist across various
subparts for CAA section 129 source categories: large municipal waste combustors (LMWC), small municipal waste combustors
(SMWC), commercial and industrial solid waste incinerators (CISWI), and other solid waste incinerators (OSWI). We are also
proposing to remove the permitting requirement for this type of ACI that are not located at major sources or subject to federal
permitting requirements for other reasons. The proposed removal would not cover ACI that are currently subject to OSWI or
LMWC rules which have already been amended to remove such permitting requirements. In the second action, the 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 requirements that would otherwise apply
to CISWI units for the combustion of commercial and industrial waste during normal operations. These additional provisions
would bring the CISWI rule subparts into alignment with existing OSWI provisions that allow such temporary use of OSWI units
to combust debris from a disaster or emergency.

DATES:

Comments must be received on or before May 4, 2026. Under the Paperwork Reduction Act, comments on the information collection
provisions are best assured of consideration if the Office of Management and Budget (OMB) receives a copy of your comments
on or before April 20, 2026.

Public hearing: If anyone contacts us requesting a public hearing on or before Wednesday, March 25, 2026, we will hold a virtual public hearing.
See
SUPPLEMENTARY INFORMATION
for information on requesting and registering for a public hearing.

ADDRESSES:

You may send comments, identified by Docket ID No. EPA-HQ-OAR-2025-0068, by any of the following methods:

• Federal eRulemaking Portal: www.regulations.gov (our preferred method). Follow the online instructions for submitting comments.

• Email: a-and-r-docket@epa.gov. Include Docket ID No. EPA-HQ-OAR-2025-0068 in the subject line of the message.

• Mail: U.S. Environmental Protection Agency, EPA Docket Center, Docket ID No. EPA-HQ-OAR-2025-0068, Mail Code 28221T, 1200 Pennsylvania
Avenue NW, Washington, DC 20460.

• Hand/Courier Delivery: EPA Docket Center, WJC West Building, Room 3334, 1301 Constitution Avenue NW,

     Washington, DC 20004. The Docket Center's hours of operation are 8:30 a.m.-4:30 p.m., Monday-Friday (except Federal holidays).

Instructions: All submissions received must include the Docket ID No. for this rulemaking. Comments received may be posted without change
to www.regulations.gov, including any personal information provided. For detailed instructions on sending comments and additional information on the
rulemaking process, see the
SUPPLEMENTARY INFORMATION
section of this document.

FOR FURTHER INFORMATION CONTACT:

For questions about this proposed rule, contact Tianzhen Nie, Natural Resources Division (E243-05), Office of Clean Air Programs,
U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, P.O. Box 12055, Research Triangle Park, North Carolina 27711;
telephone number: (919) 541-1815 and email address: nie.tianzhen@epa.gov.

SUPPLEMENTARY INFORMATION:

Participation in virtual public hearing. To request a virtual public hearing, contact the public hearing team at (888) 627-7764 or by email at NRDpublichearing@epa.gov. If requested, the hearing will be held via virtual platform on April 6, 2026. The EPA may close a session 15 minutes after
the last pre-registered speaker has testified if there are no additional speakers. The EPA will announce further details at https://www.epa.gov/stationary-sources-air-pollution/air-curtain-incinerators-only-burn-wood-wastes-yard-wastes-and.

The EPA will begin pre-registering speakers for the hearing no later than one business day after a request has been received.
To register to speak at the virtual hearing, please use the online registration form available at https://www.epa.gov/stationary-sources-air-pollution/air-curtain-incinerators-only-burn-wood-wastes-yard-wastes-and or contact the public hearing team at (888) 627-7764 or by email at NRDpublichearing@epa.gov. The last day to pre-register to speak at the hearing will be Wednesday, April 1, 2026. Prior to the hearing, the EPA will
post a general agenda that will list pre-registered speakers at: https://www.epa.gov/stationary-sources-air-pollution/air-curtain-incinerators-only-burn-wood-wastes-yard-wastes-and.

The EPA will make every effort to follow the schedule as closely as possible on the day of the hearing; however, please plan
for the hearing to run either ahead of schedule or behind schedule.

Each commenter will have four minutes to provide oral testimony. The EPA encourages commenters to submit the text of your
oral testimony as written comments to the rulemaking docket.

The EPA may ask clarifying questions during the oral presentations but will not respond to the presentations at that time.
Written statements and supporting information submitted during the comment period will be considered with the same weight
as oral testimony and supporting information presented at the public hearing.

Please note that any updates made to any aspect of the hearing will be posted online at https://www.epa.gov/stationary-sources-air-pollution/air-curtain-incinerators-only-burn-wood-wastes-yard-wastes-and. While the EPA expects the hearing to be conducted as set forth earlier, please monitor our website or contact the public hearing
team at 888-627-7764 or by email at NRDpublichearing@epa.gov to determine if there are any updates. The EPA does not intend to publish a document in the
Federal Register
announcing updates. If you require the services of a translator or special accommodation such as audio description, please
pre-register for the hearing with the public hearing team and describe your needs by Friday, March 27, 2026. The EPA may not
be able to arrange accommodations without advanced notice.

Docket. The EPA has established a docket for this rulemaking under Docket ID No. EPA-HQ-OAR-2025-0068. All documents in the docket
are listed at www.regulations.gov. Although listed, some information is not publicly available, e.g., Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Certain other material,
such as copyrighted material, is not placed on the internet and will be publicly available only in hard copy. With the exception
of such material, publicly available docket materials are available electronically at www.regulations.gov.

Instructions. Direct your comments to Docket ID No. EPA-HQ-OAR-2025-0068. The EPA's policy is that all comments received will be included
in the public docket without change and may be made available online at www.regulations.gov, including any personal information provided, unless the comment includes information claimed to be CBI, Proprietary Business
Information (PBI), or other information whose disclosure is restricted by statute. Do not submit information that you consider
to be CBI, PBI, or otherwise protected through www.regulations.gov or email. This type of information should be submitted as discussed below.

The EPA may publish any comment received to its public docket. Multimedia submissions (audio, video, etc.) must be accompanied
by a written comment. The written comment is considered the official comment and should include discussion of all points you
wish to make. The EPA will generally not consider comments or comment contents located outside of the primary submission (i.e., on the Web, cloud, or other file sharing system). For additional submission methods, the full EPA public comment policy, information
about CBI, PBI, or multimedia submissions, and general guidance on making effective comments, please visit www.epa.gov/dockets/commenting-epa-dockets.

The www.regulations.gov website allows you to submit your comment anonymously, which means the EPA will not know your identity or contact information
unless you provide it in the body of your comment. If you send an email comment directly to the EPA without going through www.regulations.gov, your email address will be automatically captured and included as part of the comment that is placed in the public docket
and made available on the internet. If you submit an electronic comment, the EPA recommends that you include your name and
other contact information in the body of your comment and with any digital storage media you submit. If the EPA cannot read
your comment due to technical difficulties and cannot contact you for clarification, the EPA may not be able to consider your
comment. Electronic files should not include special characters or any form of encryption and should be free of any defects
or viruses. For additional information about the EPA's public docket, visit the EPA Docket Center homepage at www.epa.gov/dockets.

The EPA is soliciting comments on numerous aspects in this document. The EPA has indexed each comment solicitation with a
unique identifier (e.g., “ACI-1,” “ACI-2,” “OSWI-1” . . .) to provide a consistent framework for effective and efficient provision of comments. Requests
for comment solicitation are organized by category, and can be found in sections V, VI, and XI of this preamble. Accordingly,
we ask that commenters include the corresponding identifier when providing comments relevant to that comment solicitation.
We ask that commenters include the identifier either in a heading or within the text of each comment, to make clear which
comment

  solicitation is being addressed. We emphasize that we are not limiting comments to these identified areas and encourage provision
  of any other comments relevant to this proposed action.

Submitting CBI. Do not submit information containing CBI to the EPA through www.regulations.gov or email. Clearly mark the part or all of the information that you claim to be CBI. For CBI information on any digital storage
media that you mail to the EPA, mark the outside of the digital storage media as CBI and then identify electronically within
the digital storage media the specific information that is claimed as CBI. In addition to one complete version of the comments
that includes information claimed as CBI, you must submit a copy of the comments that does not contain the information claimed
as CBI directly to the public docket through the procedures outlined in the Instructions section above. If you include other information whose disclosure is restricted by statute in your comment, clearly mark your
submission as including that information. If you submit any digital storage media that does not contain CBI, mark the outside
of the digital storage media clearly that it does not contain CBI and note the docket ID. Information not marked as CBI will
be included in the public docket and the EPA's electronic public docket without prior notice. Information marked as CBI will
not be disclosed except in accordance with procedures set forth in 40 Code of Federal Regulations (CFR) part 2. Information
whose disclosure is otherwise restricted by statute will be processed by the EPA Docket Center in accordance with the applicable
statute.

Our preferred method to receive CBI is for it to be transmitted electronically using email attachments, File Transfer Protocol
(FTP), or other online file sharing services (e.g., Dropbox, OneDrive, Google Drive). Electronic submissions must be transmitted directly to the Office of Clean Air Programs
CBI Office at the email address oaqps_cbi@epa.gov, and as described above, should include clear CBI markings and note the docket ID. If assistance is needed with submitting
large electronic files that exceed the file size limit for email attachments, and if you do not have your own file sharing
service, please email oaqps_cbi@epa.gov to request a file transfer link. If sending CBI information through the postal service, please send it to the following address:
OCAP Document Control Officer (C404-02), OCAP, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, P.O. Box 12055,
Research Triangle Park, North Carolina 27711, Attention Docket ID No. EPA-HQ-OAR-2025-0068. The mailed CBI material should
be double wrapped and clearly marked. Any CBI markings should not show through the outer envelope. Note that written comments
containing CBI and submitted by mail may be delayed and no hand deliveries will be accepted.

Preamble acronyms and abbreviations. Throughout this preamble the use of “we,” “us,” or “our” is intended to refer to the EPA. We use multiple acronyms and terms
in this preamble. While this list may not be exhaustive, to ease the reading of this document and for reference purposes,
the EPA defines the following terms and acronyms here:

ACI Air Curtain Incinerator

ANSI American National Standards Institute

CAA Clean Air Act

CBI Confidential Business Information

CFR Code of Federal Regulations

CISWI Commercial and Industrial Solid Waste Incinerator

DCOT Digital Camera Opacity Technique

EG Emission Guidelines

EPA Environmental Protection Agency

FR Federal Register

ICR Information Collection Request

LMWC Large Municipal Waste Combustor

MSW Municipal Solid Waste

NSPS New Source Performance Standards

NTTAA National Technology Transfer and Advancement Act

OMB Office of Management and Budget

OSWI Other Solid Waste Incinerator

PBI Proprietary Business Information

PRA Paperwork Reduction Act

RFA Regulatory Flexibility Act

SMWC Small Municipal Waste Combustor

TPD Tons Per Day

UMRA Unfunded Mandates Reform Act

VCS Voluntary Consensus Standard

Table of Contents

I. General Information for ACI That Only Burn Wood Wastes, Yard Waste, and Clean Lumber

A. Executive Summary

B. Does this proposed action apply to me?

C. Where can I get a copy of this document and other related information?

II. Background for ACI That Only Burn Wood Wastes, Yard Wastes, and Clean Lumber

A. What is the statutory history of this action?

B. What is the regulatory history for this action?

III. Proposed Actions for ACI That Only Burn Wood Wastes, Yard Wastes, and Clean Lumber

A. Proposed Consolidation of the Existing Opacity Limits for ACI That Only Burn Wood Wastes, Yard Wastes, and Clean Lumber

B. Proposed Removal of Existing Title V Requirements for ACI That Only Burn Wood Wastes, Yard Wastes, and Clean Lumber

IV. Summary of Cost, Environmental, and Economic Impacts for ACI That Only Burn Wood Wastes, Yard Wastes, and Clean Lumber

V. Request for Comments on Proposed Rule for ACIs That Only Burn Wood Wastes, Yard Wastes, and Clean Lumber

VI. Request for Comments on Revising the Definition of “Municipal Waste Combustion Unit” in OSWI NSPS and EG

VII. General Information for Temporary Use of CISWI Units in Disaster Recovery

A. Executive Summary

B. Does this proposed action apply to me?

C. Where can I get a copy of this document and other related information?

VIII. Background for Temporary Use of CISWI Units in Disaster Recovery

A. What is the statutory history of this action?

B. What is the regulatory history of this action?

IX. Rationale for Temporary Use of CISWI Units in Disaster Recovery

A. Temporary Use of CISWI During Disaster Recovery

B. Temporary Use Period and Notifications

X. Summary of Cost, Environmental, and Economic Impacts for CISWI Temporary Use Incinerators in Disaster Recovery

XI. Request for Comment for CISWI Temporary Use Incinerators in Disaster Recovery

XII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive Order 13563: Improving Regulation and Regulatory Review

B. Executive Order 14192: Unleashing Prosperity Through Deregulation

C. Paperwork Reduction Act (PRA)

D. Regulatory Flexibility Act (RFA)

E. Unfunded Mandates Reform Act (UMRA)

F. Executive Order 13132: Federalism

G. Executive Order 13175: Consultation and Coordination With Indian Tribal Governments

H. Executive Order 13045: Protection of Children From Environmental Health Risks and Safety Risks

I. Executive Order 13211: Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, or Use

J. National Technology Transfer and Advancement Act (NTTAA) and 1 CFR Part 51

I. General Information for ACI That Only Burn Wood Wastes, Yard Wastes, and Clean Lumber

A. Executive Summary

The EPA is proposing to consolidate the existing provisions governing Air Curtain Incinerators (ACI) and placing them in one
new rule subpart. Pursuant to Clean Air Act (CAA) section 129(g)(1)(C), the EPA has previously established in various CAA
section 129 regulations opacity limitations and associated monitoring and recordkeeping requirements for ACI that

  only burn wood wastes, yard wastes, clean lumber, or any mixture of these three materials. In this rulemaking, the EPA is
  proposing to consolidate the opacity limitations and associated monitoring, recordkeeping, and reporting requirements that
  currently exist across CAA section 129 regulations for four different solid waste incineration unit source categories: large
  municipal waste combustors (LMWC), small municipal waste combustors (SMWC), commercial and industrial solid waste incinerators
  (CISWI), and other solid waste incinerators (OSWI). The EPA is also proposing to remove the CAA title V permitting requirement
  for this type of ACI that is subject to title V under current CAA section 129 regulations and are not located at title V major
  sources or subject to title V for other reasons. In addition to the proposed actions for ACI that only burn wood wastes, yard
  wastes, and clean lumber, or any mixture of these three materials, the EPA is soliciting comment on the definition of “municipal
  waste combustion unit” in the OSWI rules. The EPA anticipates that this rule will have cost savings due to the removal of
  title V permit requirements for ACI that only burn wood wastes, yard wastes, and clean lumber. The EPA is proposing this action
  to provide relief regarding the overly burdensome permit process for States as they work to utilize ACI for natural disasters
  clean up and to mitigate wildfires. This proposal would make it easier for the EPA's regulatory partners to understand and
  comply with the regulations under CAA section 129 and speed up the permitting process across the country, while still meeting
  all statutory requirements under the CAA.

B. Does this proposed action apply to me?

Sources potentially affected by this proposed rulemaking are ACI that only burn wood wastes, yard wastes, clean lumber, or
any mixture of these three materials.

Wood waste refers to untreated wood and untreated wood products, including tree stumps (whole or chipped), trees, tree limbs
(whole or chipped), bark, sawdust, chips, scraps, slabs, millings, and shavings. Wood waste does not include yard waste (defined
later in this paragraph); construction, renovation, and demolition wastes; clean lumber (defined later in this paragraph);
treated wood or treated wood products such as wood products that have been painted, pigment-stained, or pressure treated by
compounds such as chromate copper arsenate, pentachlorophenol, or creosote; or manufactured wood products that contain adhesives
or resins (e.g., plywood, particle board, flake board, and oriented strand board). (1) Yard waste refers to grass, grass clippings, bushes, shrubs, and bush and shrub clippings from residential, commercial/retail,
institutional, or industrial sources as part of maintaining yards or other private or public lands. Yard waste does not include
construction, renovation, demolition wastes; and clean lumber, which is exempt from the definition of municipal solid waste
(MSW) in this section. Clean lumber refers to wood or wood products that have been cut or shaped and includes wet, air-dried,
and kiln-dried wood products. Clean lumber does include treated wood and treated wood products. (2)

If you have questions regarding the applicability of this action to a particular entity, consult the person listed in the

  FOR FURTHER INFORMATION CONTACT
  section.

C. Where can I get a copy of this document and other related information?

In addition to being available in the docket, an electronic copy of this document is available on the internet. Following
signature by the Administrator, the EPA also will post a copy of this document to www.epa.gov/stationary-sources-air-pollution/air-curtain-incinerators-only-burn-wood-wastes-yard-wastes-and.

A memorandum for ACI that only burn wood wastes, yard wastes, and clean lumber showing the rule edits that would be necessary
to incorporate the changes to 40 CFR parts 60 and 62 is available in the docket for this action (Docket ID No. EPA-HQ-OAR-2025-0068).
Following signature by the EPA Administrator, the EPA also will post a copy of this document to www.epa.gov/stationary-sources-air-pollution/air-curtain-incinerators-only-burn-wood-wastes-yard-wastes-and.

II. Background for ACI That Only Burn Wood Wastes, Yard Wastes, and Clean Lumber

A. What is the Agency's statutory authority for taking this action?

Section 129 of the CAA requires the EPA to establish standards for solid waste incineration units. Such standards include
emission limitations for new sources and guidelines for existing sources pursuant to CAA section 129 and 111. (3) CAA section 129(g)(1) defines a “solid waste incineration unit” as “a distinct operating unit of any facility which combusts
any material from commercial or industrial establishments or the general public (including single and multiple residences,
hotels, and motels)”; however, “solid waste incineration units” do not include “air curtain incinerators provided that such
incinerators only burn wood wastes, yard wastes and clean lumber and that such air curtain incinerators comply with opacity
limitations to be established by the Administrator by rule.” (4) Because ACI that only burn these materials and comply with the opacity limitations established by the EPA under CAA section
129(g)(1)(C) are not solid waste incineration units, they are not subject to standards for solid waste incineration units
established under CAA sections 129(a) and (b), and the only provisions in the existing section 129 regulations that apply
to these ACI are the opacity limitations and the associated requirements established under CAA section 129(g)(1)(C).

Pursuant to CAA section 129(g)(1)(C), the EPA has previously established in various CAA section 129 regulations the opacity
limitations and associated monitoring and recordkeeping requirements for ACI that only burn wood wastes, yard wastes, clean
lumber, or any mixture of these three materials. In this rulemaking, the EPA is proposing to consolidate these requirements
by removing them from existing CAA section 129 regulations and placing them in a new rule subpart specific to this type of
ACI (40 CFR part 60 subpart Ca).

The EPA is also proposing to remove the CAA title V permitting requirement for such ACI to the extent they that are currently
subject to title V under existing CAA section 129 regulations but are not located at title V major sources or subject to title
V for other reasons. (5) In 2024 the EPA amended existing Other Solid Waste Incinerator (OSWI) CAA section 129 regulations to remove the title V permitting
requirement for such ACI, (6) and in 2026 we finalized new LMWC New Source Performance Standards (NSPS) and did the same. (7) The remaining section 129 regulations that still subject such ACI to the title V permitting requirement include CISWI and
SMWC rules as well

  as the LWMC Federal Plan. The EPA is proposing to remove this requirement from these existing regulations and clarify in the
  proposed new subpart Ca that title V permits are not required for any such ACI provided that it is not a major source or subject
  to title V for other reasons. Unless provided otherwise by law, an agency may change existing positions (*e.g.,* reconsider, revise, or rescind prior actions) so long as it acknowledges the change in position, provides a reasoned explanation
  for the change, and takes any serious reliance interests into account. 8 The EPA explains below in this section and in more detail in section III.B of this document why it had previously required
  title V permitting for ACI that only burn wood wastes, yard wastes, and clean lumber and why it is proposing to remove this
  requirement for such ACI. The EPA is not aware of any serious reliance interest engendered by the current title V permitting
  requirement for these ACI and is soliciting comment on whether there is any such interest that the EPA must consider in removing
  this requirement (ACI-0).

Section 129(e) of the CAA requires that “solid waste incineration units” operate pursuant to a title V permit. (9) Section 502(a) of the CAA also requires title V permits for sources subject to regulation under CAA section 111, (10) and the EPA's regulation at 40 CFR 70.3(a) clarifies that title V permitting is required for “[a]ny source, including an area
source, subject to a standard, limitation, or other requirement under [CAA] section 111.” As explained in section III.B of
this document, the title V requirements for “solid waste incineration units” under CAA section 129(e) do not apply to ACI
that only burn wood wastes, yard wastes, clean lumber, or any mixture of these three materials because these ACI are not “solid
waste incineration units” as defined in CAA section 129(g)(1). The EPA also did not invoke CAA section 129(e) as the basis
for requiring title V permitting for such ACI in the existing section 129 regulations. (11) Rather, the EPA explained that the opacity limitations for such ACI were established pursuant to CAA sections 111 and 129,
and because these ACI are sources subject to regulation under CAA section 111, they must operate with title V permits as required
by CAA section 502(a). (12) For the reasons explained in section III.B of this document, the EPA now believes that the opacity limitations established
for these ACI are not CAA section 111 standards within the scope of section 502(a) and 40 CFR 70.3(a). Moreover, CAA section
502(a) authorizes the Administrator to exempt nonmajor source categories from title V through rulemaking. (13) The EPA also finds, in the alternative, that title V permitting is unnecessarily burdensome for these ACI and proposes to
exempt them by rule from title V requirements on that basis.

A. What is the regulatory history for this action?

As mentioned above, ACI that only burn wood wastes, yard wastes, clean lumber, or any mixture of these materials, are currently
addressed in separate CAA section 129 regulations for four different solid waste incineration unit source categories: LMWC,
SMWC, CISWI, and OSWI. These CAA section 129 regulations are as follows:

• 40 CFR part 60 subpart Cb—Emission Guidelines (EG) and Compliance Times for Large Municipal Waste Combustors That are Constructed on or Before September 20, 1994;
• 40 CFR part 60 subpart Eb—Standards of Performance for Large Municipal Waste Combustors for Which Construction is Commenced After September 20, 1994, or for Which Modification or Reconstruction is Commenced After June 16, 1996;
• 40 CFR part 60 subpart VVVV—Standards of Performance for Large Municipal Waste Combustors;
• 40 CFR part 60 subpart WWWW—Emission Guidelines and Compliance Times for Large Municipal Waste Combustors Constructed on or Before January 23, 2024;
• 40 CFR part 60 subpart AAAA—Standards of Performance for Small Municipal Waste Combustion Units for Which Construction is Commenced After August 30, 1999, or for Which Modification or Reconstruction is Commenced After June 6, 2001;
• 40 CFR part 60 subpart BBBB—Emission Guidelines and Compliance Times for Small Municipal Waste Combustors Constructed on or Before August 30, 1999;
• 40 CFR part 60 subpart CCCC—Standards of Performance for Commercial and Industrial Solid Waste Incineration Units;
• 40 CFR part 60 subpart DDDD—Emission Guidelines and Compliance Times for Commercial and Industrial Solid Waste Incineration Units;
• 40 CFR part 60 subpart EEEE—Standards of Performance for Other Solid Waste Incineration Units;
• 40 CFR part 60 subpart FFFF—Emission Guidelines and Compliance Times for Other Solid Waste Incineration Units;
• 40 CFR part 62 subpart FFF—Federal Plan Requirements for Large Municipal Waste Combustors Constructed on or Before September 20, 1994;
• 40 CFR part 62 subpart III—Federal Plan Requirements for Commercial and Industrial Solid Waste Incineration Units That Commenced Construction on or Before November 30, 1999;
• 40 CFR part 62 IIIa—Federal Plan Requirements for Commercial and Industrial Solid Waste Incineration Units That Commenced Construction on or Before June 4, 2010, and Have Not been Modified or Reconstructed Since August 7, 2013; and
• 40 CFR part 62 subpart JJJ—Federal Plan Requirements for Small Municipal Waste Combustion Units Constructed on or Before August 30, 1999. The provisions governing ACI that only burn wood wastes, yard waste, clean lumber, or any mixture of these materials, are, for the most part, the same or substantially similar across these regulations except for minor differences in definitions of an ACI and averaging times for determining compliance with applicable emissions limits. These differences are discussed further in section III.A of this document. Table 1 provides a summary of ACI definitions, applicability and exemption language, and opacity limits and averaging times across these rules.

| Category | Definition of ACI unit | Applicability | Opacity limits and
averaging times |
| --- | --- | --- | --- |
| LMWC | Incinerator that operates by forcefully projecting a curtain of air across an open chamber or pit in which burning occurs.
Incineration of this type can be constructed above or below ground and with or without refractory walls and floor | ACI located at a plant that meets the capacity specifications (greater than 250 tons per day (tpd) municipal solid waste)
and combusts 100 percent yard waste are exempt from all provisions except opacity limit, testing procedures, and reporting
and recordkeeping | 10 percent opacity limit (6-minute average).
35 percent opacity limit (6-minute average) during 30-minute startup period.Limit applies at all times except during malfunction. Malfunction periods are limited to 3 hours per occurrence. |
| SMWC | Incinerator that operates by forcefully projecting a curtain of air across as open chamber or open pit in which combustion
occurs. Incinerators of that type can be constructed above or below ground with or without refractory walls and floor | ACI that combust 100 percent yard waste and meet capacity specifications for SMWC (at least 35 tpd municipal solid waste and
no more than 250 tpd municipal solid waste) are only required to meet opacity limits, testing procedures, and recordkeeping
and reporting requirements | 10 percent opacity limit (6-minute average).
35 percent opacity limit (6-minute average) during 30-minute startup period.Malfunctions exempted, but not to exceed 3 hours. |
| CISWI | Incinerator that operates by forcefully projecting a curtain of air across an open chamber or open pit in which combustion
occurs. Incinerators of this type can be constructed above or below ground with or without refractory walls and floor | ACI located at commercial and industrial facilities that burn (1) 100 percent wood waste; (2) 100 percent clean lumber; or
(3) 100 percent mixture of only wood waste, clean lumber, and/or yard waste are only required to meet opacity limits, testing
procedures, and recordkeeping and reporting requirements | 10 percent opacity limit (average of three 1-hour blocks consisting of ten 6-minute average opacity values).
35 percent opacity limit (average of three 1-hour blocks consisting of ten 6-minute average opacity values) during 30-minute
startup period.Periods of malfunction are not exempt. |
| OSWI | Incinerator that operates by forcefully projecting a curtain of air across an open, integrated combustion chamber (fire box)
or open pit or trench (trench burner) in which combustion occurs | (A) Very small MWC subcategories: ACI that burn less than 35 tpd of only (1) 100 percent wood waste; (2) 100 percent clean lumber; (3) 100 percent yard waste;
and (4) 100 percent mixture of only wood waste, clean lumber, and/or yard waste collected from the general public and from
residential, commercial, institutional, and industrial sources

           (B) *Institutional Waste Incineration Unit subcategories:* ACI located at institutional facilities that only burn (1) 100 percent wood waste; (2) 100 percent clean lumber; (3) 100 percent
           yard waste; and (4) 100 percent mixture of only wood, clean lumber, and/or yard waste generated at that facility
           ACI as described in (A) and (B) above are only required to meet opacity limits, testing procedures, and recordkeeping and
           reporting requirements | 10 percent opacity limit (6-minute average).
           35 percent opacity limit (6-minute average) during 30-minute startup period.Limits apply at all times except during malfunction. |

There are also differences among the current title V permitting requirements for this type of ACI across CAA section 129 rule
subparts. For example, the OSWI rules do not require a title V permit for ACI that only burn wood wastes, yard wastes, and
clean lumber if they “are not otherwise required to obtain a title V permit.” (14) Similarly, the EPA removed the title V permit requirement for ACI that only burn wood wastes, yard wastes, and clean lumber
and are not located at a major source or subject to title V for other reasons in the 2026 LMWC final rule. (15) However, similar ACI, such as those subject to the CISWI or SMWC rules and LMWC Federal Plan, must obtain a title V permit
under current regulations. (16)

In this rulemaking, the EPA is proposing to consolidate regulatory provisions governing ACI that only burn wood wastes, yard
wastes, clean lumber, or any mixture of these materials, by removing them from existing CAA section 129 regulations and placing
them in a new rule subpart specific to this type of ACI. (40 CFR part 60 subpart Ca). Also, because these ACI are materially
indistinguishable regardless of which CAA section 129 source category they are currently regulated under and therefore need
to be treated in a consistent manner, the EPA is proposing to remove the title V permitting requirement for these ACI that
are currently regulated under the CAA section 129 regulations for CISWI, SMWC, and the LMWC Federal Plan. This is consistent
with the EPA's 2024 final rule that removed title V permitting for these ACI in the existing CAA section 129 OSWI regulations (17) and its 2026 amendments to the LMWC NSPS and EG. (18) For the new subpart Ca, the EPA is proposing that title V permits are not required provided that the ACI is not a major source
or subject to title V for other reasons.

Please note that the proposed new subpart Ca does not directly apply to existing sources subject to state plans that implement
CAA section 129 EGs. However, if finalized, States that currently require title V permitting in their state plans would be
able to revise their plans to remove the title V permitting requirement for this type of ACI.

III. Proposed Actions for ACI That Only Burn Wood Wastes, Yard Wastes, and Clean Lumber

A. Proposed Consolidation of the Existing Opacity Limits for ACIs That Only Burn Wood Wastes, Yard Wastes, and Clean Lumber

The EPA is proposing to consolidate requirements for ACI that only burn wood wastes, yard wastes, clean lumber, or any mixture
of these materials, by removing them from existing CAA section 129 regulations and placing them in a new rule subpart specific
to

  this type of ACI, 40 CFR part 60 subpart Ca. The proposed subpart Ca includes certain consolidated changes as described below.

The EPA is proposing a single definition for any ACI that burns only wood wastes, yard wastes, clean lumber, or any mixture
of these materials. In the CAA section 129 rules governing LMWC, SMWC, and CISWI, an ACI is defined as an “incinerator that
operates by forcefully projecting a curtain of air across an open chamber or pit in which burning occurs. Incineration of
this type can be constructed above or below ground and with or without refractory walls and floor.” (19) The OSWI rules define ACI slightly differently as an “incinerator that operates by forcefully projecting a curtain of air
across an open, integrated combustion chamber (fire box) or open pit or trench (trench burner) in which combustion occurs.” (20)

We are proposing to adopt the OSWI regulation definition in the new subpart Ca for the following reasons. First, this definition
specifically includes fire box and trench burner unit types that are commonly used for cleanup and disposal of wood wastes,
yard wastes, and clean lumber while not excluding other potential types of units. Second, the part of the ACI definition in
the CISWI, LMWC, and SMWC rules that the unit “can be constructed above or below ground and with or without refractory walls
and floor” appears redundant (e.g., construction can only be above or below ground—there is no third choice); without this phrase, ACI can still be constructed
either above or below ground. Please note that the proposed definition is independent of unit design capacity and type of
facility that owns or operates the unit, and so the choice of definition is not intended to and should not result in material
differences in applicability or requirements imposed. We solicit comment on the proposed definition of ACI (ACI-1).

The proposed new subpart Ca would consolidate existing opacity limitations during periods of regular operation for this type
of ACI and during the startup period of the unit. The opacity limits in the new subpart Ca would be the same as those across
all existing CAA section 129 regulations (i.e., 10 percent opacity during regular operation and 35 percent opacity during startup). (21) This proposal merely consolidates these longstanding opacity limitations for clarity and administrability and does not reopen
them for comment.

The EPA also proposes to create a single set of opacity measurement averaging time requirements that are clear and consistent
with the methodologies of EPA Method 9, a compliance determination method for opacity that is required in the LMWC, SMWC,
OSWI, and CISWI rules. (22) We are proposing that compliance with the opacity limit will be based on 6-minute averages, as provided in the 40 CFR part
60 General Provisions at 40 CFR 60.11(b). This is the current requirement in all CAA section 129 rules except the CISWI rules, which require that
the determination be based on “three 1-hour blocks consisting of ten 6-minute average opacity values.” (23) Under 40 CFR 60.11(b), “the minimum total time of observations shall be 3 hours” and the 3 hours are comprised of 30 6-minute
averages. While the minimum observation period under the CISWI rules is also 3 hours, CISWI requires averaging the ten values
for each 1-hour block and then averaging the three 1-hour block values, making the final value less representative of the
individual 6-minute average values and in turn providing less confidence in determining whether there is an opacity concern,
which would be indicative of a combustion issue that needs to be addressed. We did not find in the CISWI rule records an explanation
for why the EPA chose to depart from 40 CFR 60.11(b) or why the averaging method in CISWI rules differ from other CAA section
129 rules. (24) As mentioned earlier in this preamble, the purpose of this proposed rulemaking is to have one set of requirements for all
ACI that only burn wood wastes, yard wastes, clean lumber, or a mixture thereof. Because all the other rules follow 40 CFR
60.l1(b), we are proposing to apply the averaging requirement in 40 CFR 60.11(b) in the proposed consolidated new rule subpart
Ca. We solicit comment on these proposed averaging time requirements (ACI-2).

In addition to creating a single set of averaging time requirements, the EPA is proposing to include text clarifying the opacity
monitoring requirements. One of these clarifications describes how compliance is demonstrated when conducting opacity measurements;
this clarification is consistent with our discussion on averaging times above. This clarification is especially needed for
periods of startup, as the startup period is only 30 minutes. The EPA has previously received questions on how owners and
operators are supposed to comply with 40 CFR 60.8 during the startup period, as 40 CFR 60.8 requires three test runs. The
additional regulatory text would clarify that owners and operators only need to make observations for 30 minutes to demonstrate
compliance during startup. We also propose to add a cross-reference to 40 CFR 60.11 for performance tests, as this section
of the General Provisions provides instructions for conducting opacity measurements.

Currently, the LMWC, CISWI, and OSWI rules require an annual performance test, which must be conducted within 12 months following
the date of the previous test. (25) However, the SMWC rule's required annual performance test must be conducted “no more than 13 months following the date of
the previous test.” (26) To maintain consistency across ACI within the new subpart, we are proposing to require that the annual performance tests must
be conducted within 12 months of the date of the previous test. We solicit comment on the proposed timeframe for these annual
performance tests (ACI-3).

Currently, the OSWI rules state: “If the air curtain incinerator has been out of operation for more than 12 months following
the date of the previous test, then the owner or operator must conduct a test for opacity upon startup of the unit.” (27) However, this language does not appear in the CISWI, LMWC, or SMWC rules. Therefore, the EPA is proposing to include in the
new subpart Ca a provision similar to that in the OSWI rules but with further clarification. Specifically, the EPA is proposing
that any ACI that is not in operation at the time the annual test is due (12 months from the previous test) is not required
to conduct a test for opacity at that time. Without this language, owners and operators could assume that they must start
up their unit to conduct annual testing, which would be an unnecessary burden for the owner or operator and would tend to
increase, rather than control, emissions at a non-operating unit—a counterintuitive result with no environmental benefit.
Therefore, we are proposing to delay testing until the next startup for any ACI that is not operating at the time of scheduled
testing. Specifically, the proposed new subpart Ca would state:

  “If the air curtain incinerator is not operating at the time that the annual test would be required under paragraph (c) of
  this section, you may delay the annual test until the next day you operate the unit.” We solicit comment on this proposed
  requirement (ACI-4).

The EPA is also proposing to require the completion of an initial performance test within 60 days of the initial startup.
Currently, the timeline for conducting the initial performance test in all the different CAA section 129 regulations is within
60 days after reaching the operational charge rate but no later than 180 days after initial startup. (28) Since the performance test is used to demonstrate compliance, allowing up to 180 days of startup for performance testing seems
unreasonably long in this case. The “up to 180 days” is a default maximum timeframe provided in the General Provisions, which may be necessary for complicated sources with multiple air pollution control devices that may need time to fully begin
operations and work through issues that can occur during initial startup. This is often referred to as a shakedown period.
During the shakedown period, sources generally ramp up operations over time to protect the unit against operational problems
like thermal stress, overheating, and leaks. We do not expect ACI that only burn wood wastes, yard wastes, and clean lumber,
or mixtures of these materials, and are subject only to opacity limits, to require a long shakedown period. Such ACI are less
complicated than other sources that are required to conduct performance testing, and as such, we would expect that these units
can reach their operational charge rate not long after startup; therefore, we expect that these units should be able to conduct
initial performance tests within 60 days of startup.

This proposed rulemaking also includes initial notification requirements. These would require the submission of an initial
notification of startup of this type of ACI, location of the ACI unit, initial startup date, and types of materials burned
in the ACI. Previous notification requirements for this type of ACI did not include the location of the ACI unit. We are proposing
this requirement because we believe it would be helpful for the EPA, State, and local authorities to maintain an inventory
of where these units are located, particularly given the proposed removal of title V permit requirements detailed in section
III.B of this document. We solicit comment on these proposed initial notification requirements (ACI-5).

This rulemaking also proposes recordkeeping and reporting requirements for initial and annual opacity tests for this type
of ACI. For such ACI currently regulated under the OSWI rules, owners and operators must keep records of these opacity tests
in either a paper copy or computer-readable (e.g., electronic) format for at least 5 years. (29) These records must be kept on site for at least 2 years but then may be kept off site for the remaining 3 years. These test
results must be submitted to the Administrator (as paper or electronic copy). For initial opacity tests, results must be submitted
within 60 days of the test. For annual opacity tests, results must be submitted within 12 months following the previous report.
The recordkeeping and reporting requirements for this type of ACI regulated under the CISWI rules are identical to those in
the OSWI rules, with the exception of requiring records of these opacity tests be kept on site for the entire 5-year recordkeeping
period. (30) Like units regulated under CISWI, this type of ACI regulated under the LMWC and SMWC rules are required to keep records (paper
or electronic copy) of these opacity tests on site for 5 years. (31) However, opacity test results are to be submitted to the Administrator by February 1 of the following year, rather than 60
days from the initial test for initial reports, or 12 months from submittal of the previous test for annual reports. In this
case, the degree of flexibility afforded to owners and operators of these ACI for compliance with this reporting requirement
could vary greatly depending on when during the calendar year an initial opacity test is performed. For this proposed rulemaking,
we are basing the recordkeeping and reporting requirements on those in the OSWI rules, as we believe the language provides
the greatest degree of specificity for these respective requirements. We solicit comment on the proposed recordkeeping and
reporting requirements for these ACI (ACI-6).

B. Proposed Removal of Existing Title V Requirements for ACI That Only Burn Wood Wastes, Yard Wastes, and Clean Lumber

We are proposing to remove the title V permitting requirements for ACI that only burn wood wastes, yard wastes, clean lumber,
or any mixture of these materials, that were previously covered by CAA section 129 CISWI and SMWC regulations as well as the
LWMC Federal Plan, provided they are not otherwise subject to title V. (32) The EPA made the same amendments in the revised OSWI rule in 2024 (33) and the LMWC rule in 2026. (34)

The EPA is proposing to remove the title V permitting requirement for this type of ACI for the following reasons. First, CAA
section 129(e) and the EPA's title V regulation at 40 CFR 70.3(b)(1), which require that each solid waste incineration unit
operate with a title V permit, do not by their terms apply to ACI that only burn wood wastes, yard wastes, or clean lumber
and that are subject to opacity limitations established by the EPA. These ACI are not “solid waste incineration units” as
defined in CAA section 129(g)(1)(C) and are therefore not subject to title V permitting under CAA section 129(e) or 40 CFR
70.3(b)(1).

Second, while CAA section 502(a) and the EPA's title V regulations at 40 CFR 70.3(a)(2) require that sources subject to CAA
section 111 standards operate with a title V permit, the opacity limits for ACI that only burn wood wastes, yard wastes, clean
lumber, or any mixture of these materials, are not section 111 standards. As mentioned earlier, the EPA had previously claimed
that the opacity limits for these ACI “were established pursuant to CAA sections 111 and 129” and thereby triggered CAA section
502 requirement that sources subject to regulation under CAA section 111 must operate with title V permits. (35) However, the EPA now believes that prior assertion to be inaccurate for the following reasons. First, the opacity limitations
and related requirements for these ACI were established under CAA section 129(g)(1)(C), which does not require the EPA to
establish such opacity limitations under CAA section 111. Second, while certain section 129

  provisions require that standards be established pursuant to CAA sections 111 and 129, it does not appear that the opacity
  limitations for these ACI were established pursuant to any such section. For example, CAA section 129(a) requires the EPA
  to establish standards “pursuant to section [111] of this title and this section for each category of solid waste incineration
  units.” As noted above, because these ACI are not solid waste incineration units, section 129(a) does not apply to such ACI.
  Similarly, CAA section 129(a)(2) requires that “standards applicable to solid waste incineration units” promulgated under
  section [111 and 129] shall reflect the maximum degree of reduction in emissions of air pollutants listed under section (a)(4)
  that the Administrator, taking into consideration the cost of achieving such emission reduction, and any non-air quality health
  and environmental impacts and energy requirements, determines is achievable for new or existing units in each category.” CAA
  section 129(a)(4), in turn, provides that standards promulgated under sections 111 and 129 and “applicable to solid waste
  incineration units shall” include opacity limits “as appropriate.” However, as noted above, ACI burning only wood wastes,
  yard wastes, clean lumber, or mixtures thereof are not solid waste incineration units under CAA section 129(g)(1)(C). Therefore,
  the EPA is not required by CAA section 129(a)(2) and (4) to establish opacity limits for such ACI units pursuant to sections
  111 and 129. Nor is there any record showing that the opacity limits for this type of ACI were established pursuant to sections
  111 and 129 in accordance with CAA section 129(a)(4). The EPA first established the opacity limits for ACI that only burn
  yard wastes in 1995. [(36)]() The EPA explained at the time that it was directed by CAA section 129 to establish such opacity limits [(37)]() and that the limits “are based on levels achieved by well-designed and operated air curtain incinerators.” [(38)]() The EPA subsequently promulgated the same opacity limits for ACI that only burn wood wastes and clean lumber. [(39)]() In neither rulemaking did the EPA explain how the standards were established pursuant to CAA sections 111.

For the reasons stated above, we do not believe that the opacity limitations established under CAA section 129(g)(1)(C) for
ACI that only burn wood wastes, yard wastes, clean lumber, or any mixture thereof are CAA section 111 standards; therefore,
these opacity limitations do not trigger the title V permitting requirement for this type of ACI.

Third, CAA section 502(a) authorizes the Administrator to promulgate regulations to exempt non-major sources from the title
V permitting requirement if the Administrator finds, in his discretion, that compliance with such requirement is impracticable,
infeasible, or unnecessarily burdensome. Such an exemption is not required in this case because, as proposed above, the statute
does not require title V permitting for ACI that only burn wood wastes, yard wastes, clean lumber, or any mixture thereof.
Nevertheless, the EPA finds, in the alternative, that compliance with title V permitting is unnecessarily burdensome for this
type of ACI. Under this alternative, even if it were determined that such ACI are CAA section 111 standards subject to title
V permitting requirements under CAA section 502(a) and the EPA's regulation at 40 CFR 70.3(a)(2), we would nevertheless exempt
such sources from title V requirements on that basis. During the prior CISWI rulemakings, the EPA had acknowledged that it
could exempt nonmajor sources from title V permitting by making the necessary finding under CAA section 502 but had declined
to do so for these ACI because the EPA had not made such finding for these ACI in other CAA section 129 rules and believed
that it was important to treat these ACI in the same manner. (40) As mentioned earlier, in 2024 the EPA amended existing OSWI section 129 regulations to remove the title V permitting requirement
for such ACI. (41 42) The EPA is treating these ACI in the same manner by proposing to remove the title V permitting requirement for units regulated
under the remaining section 129 regulations that currently require title V permitting for these ACI.

The EPA has previously developed a four-factor balancing test in determining under CAA section 502(a) whether compliance with
title V is “unnecessarily burdensome.” These four factors are: (1) whether title V permitting would result in significant
improvements in compliance with emission standards; (2) whether title V permitting would impose significant burdens on the
area source category; (3) whether the costs are justified, taking into account potential gains; and (4) whether there are
existing enforcement programs in place sufficient to ensure compliance. (43) The EPA has historically also considered whether such an exemption would adversely affect public health, welfare, or the environment. (44) In exercising the discretion conferred by statute, the Administrator considers these factors in combination, and not every
factor must point in the same direction to support an exemption. As explained below, the EPA considers and balances these
same factors in this action.

With respect to the first factor, the EPA does not believe that title V permitting would result in significant improvements
in compliance with emission standards. One of the primary benefits of the title V program is to compile and clarify, in a
single document, the various and complex regulations that apply to a facility in order to improve compliance and thereby “enable
the source, states, EPA, and the public to understand better the requirements to which the source is subject, and whether
the source is meeting those requirements.” (45) However, this benefit is not realized with respect to ACI that only burn wood wastes, yard wastes, clean lumber, or mixtures
thereof; these ACI are subject only to opacity limitations and associated monitoring recordkeeping and reporting requirements
established under CAA section 129(g)(1)(C), and we are not aware that they are subject to any other requirement under the
CAA. Another way title V can improve compliance is its requirement that “ [e]ach permit. . . shall set forth . . . monitoring . . . requirements to assure compliance with the permit terms and conditions.” (46) This rulemaking, however, would adopt and consolidate the monitoring, recordkeeping and reporting requirements for these ACI
in the current CAA section 129 rules with some minor variations as detailed previously in section III.A. of this document.
Specifically, opacity would be monitored according to EPA Method 9, a long established and common practice for determining
compliance with opacity limits. The owners and operators of these sources would perform an initial opacity test no later than
60 days after initial startup, and annual opacity tests no later than 12 calendar months following the date of

  the previous test, unless the ACI is not operating at the time that the annual test would be required. Owners and operators
  would submit the results of each opacity test to the Administrator no later than 60 calendar days after the date of completing
  the test. Records of these opacity tests would be kept in either paper copy or electronic format for at least 5 years; they
  would be kept on site for at least 2 years, then could be kept off site for the remaining 3 years. These requirements have
  been adequate to ensure compliance with the ACI opacity limits currently in the existing CAA section 129 regulations for various
  source categories. Although title V requires submitting reports of any required monitoring at least every 6 months, per 40
  CFR 70.6(a)(3)(iii)(A), we do not think more frequent reporting is necessary for purposes of ensuring compliance with one
  single opacity limit. In light of the above, we believe that the proposed monitoring, recordkeeping, and reporting requirements
  of this proposed rulemaking would be sufficient to ensure compliance, and that title V would not significantly improve compliance.

Regarding the second factor, we believe that title V permitting would impose significant burdens on the owners and operators
of these sources. Costs associated with initial application and annual fees for a title V permit can vary depending on state
permitting policies. (47) The permitting process, which includes preparing and submitting the permit applications, meeting with the permitting authorities
and subjecting their operations and permit application to public comment, takes time and could potentially delay operations.
Considering the above, we believe that title V requirements would impose a significant additional burden without corresponding
health or environmental benefit. (48)

Regarding the third factor, we believe the title V permitting costs and other burdens are not justified as we believe there
would be little, if any, potential gain in compliance from subjecting this type of ACI to title V. It is likely that many
ACI that burn exclusively wood wastes, yard wastes, clean lumber, or mixtures thereof are commonly located at facilities that
would not otherwise require a title V operating permit, such as land clearing operations in public or private land and fuels
treatment for wildfire prevention. (49) State and industry stakeholders have commented that the title V requirements for these units are overly burdensome and costly,
particularly in light of the dependence on ACI units to mitigate natural disaster debris, such as massive amounts of clean
wood and vegetative waste for wildfire mitigation and forest management, burning of storm-generated wood and vegetative debris,
and burning of land clearing debris. Several States have commented that these ACI should not be required to obtain title V
permits because they are low-emitting and because permitting these ACI is unnecessarily burdensome and expensive. Further,
ACI that burn exclusively wood wastes, yard wastes, clean lumber, or any mixtures thereof are often used temporarily at the
location of a natural disaster or disaster prevention, not at facilities that are subject to title V. As mentioned earlier
in this preamble, the only requirements for these ACI are opacity limitations and associated monitoring, recordkeeping, and
reporting requirements that we believe are adequate to assure compliance. In light of the above, we conclude that the cost
of title V permitting is not justified as we do not anticipate any potential gain in health and environmental outcomes from
compliance by these ACI with additional title V requirements.

Regarding the fourth factor, we believe there are existing enforcement programs in place sufficient to ensure compliance with
opacity limits for these ACI. State and local authorities can monitor compliance with these opacity limits and related requirements
with delegated authorities for implementing and enforcing CAA section 129 regulations; the EPA is aware of no indication that
these section 129 delegated authorities are insufficient to assure compliance with these requirements, which as mentioned
above have been in place for a long time and are common practices. Therefore, enforcement of these opacity limits and related
requirements through title V permitting is not necessary.

Lastly, requiring title V permitting for these ACI could adversely affect public health, welfare, or the environment by diverting
resources toward permitting activities unlikely to generate additional health or environmental benefits. Since compliance
with the opacity limitations for these ACI can be adequately assured without title V, as explained above, title V permitting
would unnecessarily shift State resources away from assuring compliance for major sources and potentially reducing overall
air program effectiveness. We therefore find title V permitting to be unnecessarily burdensome for ACI that only burn wood
wastes, yard wastes, clean lumber, or any mixture thereof, and that are not major sources or subject to title V permitting
requirements for another reason.

In sum, the title V requirements for “solid waste incineration units” and sources subject to CAA section 111 standards do
not apply to ACI that only burn wood wastes, yard wastes, clean lumber, or any combination thereof, because these ACI are
not “solid waste incineration units” under CAA section 129(g)(1) and the opacity limitations established for these ACI are
not CAA section 111 standards. We also find, in the alternative, that title V requirements would be unnecessarily burdensome
for this type of ACI. For the reasons stated above, we propose to remove from CAA section 129 regulations any existing title
V permitting requirements for ACI that only burn wood wastes, yard wastes, and clean lumber, and state in the new subpart
for this type of ACI that these ACI are not required to obtain a title V operating permit, provided that they are not otherwise
required to obtain a title V operating permit.

IV. Summary of Cost, Environmental, and Economic Impacts for ACI That Only Burn Wood Wastes, Yard Wastes, and Clean Lumber

This proposed rulemaking would consolidate the opacity limits and associated monitoring, recordkeeping and reporting requirements
that currently exist across the OSWI, CISWI, LMWC, and SMWC rules for ACI that only burn wood wastes, yard wastes, clean lumber,
or any mixture of these materials. The only additional cost that we anticipate is the cost of the initial notification requirement
for ACI that only burn wood wastes, yard wastes, clean lumber, or any mixture of these materials. However, consistent with
the current OSWI and LMWC rulemakings, we are proposing to remove title V requirements for ACI that only burn wood wastes,
yard wastes, clean lumber, or any mixture of these materials. We anticipate that the removal of the title V requirements would
result in cost savings for such ACI that are not co-located at facilities with CISWI and

  SMWC units currently required to obtain a title V permit for these types of ACI. We do not anticipate any changes to emissions
  because no new emission standards are being set. With the removal of title V permitting requirements and the likelihood of
  associated net cost savings and the associated reduced overall cost of operation, there could be an increase in ACI use. This
  potential increase in ACI use could generate increased emissions. We are unable to quantify emissions changes of this nature
  for this proposed rulemaking but anticipate that they would be small, particularly given the retention of existing opacity
  limits for these units. We anticipate net savings because the cost of removing the title V requirements will outweigh any
  costs associated with the initial notification requirement. Hence, we anticipate that there will not be adverse economic impacts
  for those entities that use these types of ACI.

V. Request for Comments on Proposed Rule for ACI That Only Burn Wood Wastes, Yard Wastes, and Clean Lumber

We solicit comment on all aspects of this proposed action described above. In addition to general comments on this proposed
action, we are soliciting comments on the following topics. A comment reference indicator for each specific topic is provided
(e.g., ACI-1, ACI-2, etc.).

• Whether the existing title V permitting requirement for ACI that only burn wood wastes, yard wastes, and clean lumber, of any mixture thereof, has engendered any serious reliance interest that the EPA must consider in removing this permitting requirement. (ACI-0).

• The definition of ACI as an “incinerator that operates by forcefully projecting a curtain of air across an open, integrated
  combustion chamber (fire box) or open pit or trench (trench burner) in which combustion occurs” as discussed in section III.A
  of this document. (ACI-1).
  • The averaging time requirement that compliance for opacity is based on 6-minute averages, as provided in the 40 CFR part
  60 General Provisions at 40 CFR 60.11(b), as discussed in section III.A of this document. (ACI-2).

• The timeframe that annual performance tests be conducted within 12 months of the date of the previous test as discussed in
  section III.A of this document. (ACI-3).

• The ability to delay an annual performance test until the next startup of the unit if the ACI is not operating at the time
  that the annual test is required as described in section III.A of this document. (ACI-4).

• The initial notification requirement for this type of ACI as described in section III.A of this document. (ACI-5).

• Recordkeeping and reporting requirements as described in section III.A of this document. (ACI-6).

VI. Request for Comment on Revising the Definition of “Municipal Waste Combustion Unit” in OSWI NSPS and EG

In addition to the proposed action on ACI that only burn wood wastes, yard wastes, and clean lumber, or any mixture of these
materials, the EPA is soliciting comment on revising the definition of “municipal waste combustion unit” in the OSWI NSPS
and EG to remove the reference to “pyrolysis/combustion units.” In the preamble to the 2005 OSWI final rule, the EPA stated
that “pyrolysis/combustion units (two chamber incinerators with a starved air primary chamber followed by an afterburner to
complete combustion)” are considered OSWI units but did not further elaborate. (50) The EPA proposed in 2020 to modify the definition of “municipal waste combustion unit” in the OSWI rules to remove the reference
to pyrolysis/combustion units. The EPA published an advanced notice of proposed rulemaking on September 8, 2021 (86 FR 50296),
to gather more details on pyrolysis/combustion units, including how they are used, the inputs and products of the processes,
and emissions from these processes. In 2023, the EPA proposed to withdraw the 2020 proposed definition change. (51) To assist with the resolution of this longstanding issue, we are soliciting comment on whether removing the reference to “pyrolysis/combustion
units” from the definition of “municipal waste combustion unit” in the OSWI rules is appropriate or not, along with supporting
legal, policy, and factual arguments for the commenter's recommended position. (OSWI-1).

VII. General Information for Temporary Use of CISWI Units in Disaster Recovery

A. Executive Summary

The EPA is proposing to allow the temporary use of incineration units subject to CISWI regulations during disaster recovery
without the need to comply with CAA section 129 requirements. In 2005, the EPA promulgated the OSWI NSPS (40 CFR part 60,
subpart EEEE) and EG (40 CFR part 60, subpart FFFF). (52) Those regulations established CAA section 129 standards and associated requirements for OSWI units, and authorized OSWI to
combust debris from a disaster or emergency on a temporary basis without having to comply with applicable CAA section 129
requirements. In this rulemaking, we are proposing to authorize such temporary use for incinerators (including ACI) subject
to CISWI regulations by adding temporary-use provisions similar to those in the OSWI regulations to existing Federal CISWI
rule subparts. The EPA does not anticipate any additional capital costs associated with this proposal if finalized, only notification
costs. This proposed action works to permanently respond to States' request for more incinerators to be available for disaster
clean up. By proposing this action, the EPA is working to streamline responses to natural disasters and emergencies and to
advance cooperative federalism.

B. Does this proposed action apply to me?

Categories and entities potentially affected by this proposed rulemaking are those that operate incinerators (including ACI)
subject to CISWI NSPS (40 CFR part 60, subpart CCCC), Federal Plan (40 CFR part 62, subpart IIIa), or EG (40 CFR part 60,
subpart DDDD) (hereinafter collectively referred to as “CISWI” (53)). If you have questions regarding the applicability of this action to a particular entity, consult the person listed in the

  FOR FURTHER INFORMATION CONTACT
  section.

C. Where can I get a copy of this document and other related information?

The EPA has established a docket for CISWI Temporary Use Incinerator rulemaking under Docket ID No. EPA-HQ-OAR-2003-0119.
Following signature by the EPA Administrator, the EPA also will post a copy of this document to https://www.epa.gov/stationary-sources-air-pollution/commercial-and-industrial-solid-waste-incineration-units-ciswi-new.

VIII. Background for Temporary Use of CISWI Units in Disaster Recovery

A. What is the statutory authority for taking this action?

Section 129 of the CAA, entitled “Solid Waste Combustion,” requires the

  EPA to develop and adopt NSPS and EG for solid waste incineration units pursuant to CAA section 111. [(54)]() Section 111(b) of the CAA requires the EPA to establish NSPS for new sources, and CAA section 111(d) requires the EPA to establish
  procedures for States to submit plans for implementing EG for existing sources. The EPA promulgates Federal plans to regulate
  existing sources where there are no approved state plans.

Section 129(a)(1) of the CAA identifies five categories of solid waste incineration units and requires emissions standards
for “each category of solid waste incineration unit.” The five categories of solid waste incineration units are as follows:

(1) Units with a capacity of greater than 250 tpd combusting municipal waste;

(2) Units with a capacity equal to or less than 250 tpd combusting municipal waste;

(3) Units combusting hospital, medical and infectious waste;

(4) Units combusting commercial or industrial waste;

(5) “other categories of solid waste incineration units.”

While the CAA specifically describes four of the five listed categories by the types of wastes burnt, it leaves unspecified
the “other categories of solid waste incineration units.” As the EPA observed during the development of standards for OSWI,
Congress could have unambiguously required OSWI to cover “every other possible type of incineration unit burning any type
of solid waste” but did not to do so, thereby leaving to the EPA's discretion to delineate those “other” categories of solid
waste incineration units. (55) Based on that authority, the EPA defined OSWI to include very small municipal combustion units and institutional waste combustion
incineration units. The EPA analyzed and excluded various types of incinerators from being subject to CAA section 129 standards;
among those excluded are incinerators when they are used on a temporary basis to combust debris during disaster recovery.
The EPA determined that some incinerators “should be handled differently due to unusual circumstances (e.g., unique geographic locations or climatic factors, temporary emergency use)” that would render compliance with CAA section 129
rules infeasible. (56) Accordingly, the EPA excluded incinerators from complying with CAA section 129 standards and associated requirements when
they are used to combust debris during disaster recovery. (57) To qualify for this exclusion, an incinerator “must burn debris in an area declared a State of Emergency by a local or State
government, or the President, under the authority of the Stafford Act, has declared that an emergency or a major disaster
exists in the area.” (58) In addition, owners and operators must follow the notification requirements in the temporary use provisions. (59)

Currently, these temporary use provisions are codified in the Federal OSWI regulations, and the EPA has realized that States
need more incinerators for emergency/disaster debris cleanup. Some States have requested the temporary use of CISWI for such
purposes; (60) based on the same authority and for the same reasons explained in the 2005 OSWI rule (61) and here in section VIII.B. of this preamble, the EPA is proposing to include similar temporary use provisions for disaster
recovery in CISWI regulations, thereby extending such temporary use to incinerators at commercial and industrial facilities
upon final promulgation.

The proposed action does not affect the EPA's obligation under CAA section 129(a)(1)(C) to establish standards for “solid
waste incineration units combusting commercial and industrial wastes.” This action proposes to provide for the temporary use
of incinerators that normally burn commercial or industrial wastes to instead burn debris (which is defined in the Webster
Dictionary as remains of materials broken or destroyed, in this case by a natural disaster or emergency) during disaster recovery
without having to comply with CISWI standards established pursuant to CAA section 129(a)(1)(c); the temporary use provisions
do not apply to combustion of commercial and industrial wastes (i.e., wastes generated by commercial and industrial facilities) for which standards are required under CAA section 129(a)(1)(C).
The EPA, therefore, concludes that these incinerators that are normally used at commercial and industrial facilities to burn
commercial or industrial wastes need not comply with CAA section 129 emission standards and associated requirements for CISWI
while they are used to combust debris if they only burn non-hazardous debris and not waste from normal operations at their
commercial and industrial facilities during the temporary use period.

Please note that while the EPA is proposing to amend the CISWI EG (40 CFR part 60, subpart DDDD), along with the CISWI NSPS
and Federal plan, to include the temporary use provisions, the CISWI EG does not directly apply to existing incinerators covered
by that EG. However, if finalized, States may revise their State plans implementing subpart DDDD to add the temporary use
provisions that would be in subpart DDDD, thereby allowing their existing incinerators at commercial or industrial facilities
to be used temporarily for emergency/disaster debris clean up without complying with their CAA section 129 standards during
that period.

B. What is the regulatory history for this action?

In 2005, the EPA promulgated the OSWI NSPS (40 CFR part 60, subpart EEEE) and EG (40 CFR part 60, subpart FFFF). (62) Those regulations established CAA section 129 standards and associated requirements for OSWI units; however, the regulations
also allow temporary use of incinerators to burn debris during disaster recovery or other emergencies without complying with
such standards. Because these OSWI regulations are currently the only CAA section 129 regulations with such temporary use
provisions, only incinerators subject to the OSWI NSPS or State plans implementing the OSWI EG may be used on a temporary
basis to combust debris from a disaster or emergency without complying with CAA section 129 requirements during that period.

On January 24, 2025, President Trump issued Executive Order (E.O.) 14181 to expedite cleanup of the catastrophic wildfires
in Los Angeles County. (63) The E.O. sparked renewed awareness of regulatory challenges associated with disaster recovery, which have increased in both
intensity and costliness in recent years. (64) During disaster cleanup, frequently there is considerable excess organic waste that, if left, would

  decompose into more harmful organic air emissions than if combusted or landfilled. Incinerators are useful tools for disaster
  or emergency cleanup, as they can process large quantities of debris and are considered safer and more environmentally sound
  than other remediation options. [(65)]() When Hurricane Helene hit in September 2024, States and municipalities expressed concern over smoke impacts from open burning
  of waste and debris, and increased likelihood of wildfires. [(66)]() To respond to the scale of the disaster and volume of debris generated, the EPA's Regional offices and Office of Enforcement
  and Compliance Assurance issued No Action Assurances to allow North Carolina and Tennessee to use their CISWI ACI units to
  combust non-hazardous disaster debris, as ACI can be easily mobilized to reduce waste volume and minimize harmful environmental
  impacts. [(67)]() This situation highlighted the need for additional available incinerator capacity for States during disasters, beyond those
  that could be made available under the Federal OSWI regulations. In this action, the EPA is proposing to include temporary
  use provisions in the Federal CISWI regulations similar to those in the Federal OSWI regulations, increasing the incinerator
  capacity available to combust non-hazardous disaster debris during disaster or emergency events. These provisions were previously
  published by the EPA in a final agency action Interim Final Rule (IFR); however, due to the conclusion of the hurricane and
  wildfire seasons of 2025, the EPA is withdrawing the IFR and proposing those provisions through a notice-and-comment rulemaking
  action. The provisions propose to exclude incinerators subject to CISWI from CAA section 129 requirements when they are used
  on a temporary basis to combust debris from a disaster or emergency such as a tornado, hurricane, flood, ice storm, high winds,
  or act of bioterrorism. Such temporary use provisions are being proposed in the following CAA section 129 regulations:

• 40 CFR part 60, subpart CCCC—Standards of Performance for Commercial and Industrial Solid Waste Incinerations Units;
• 40 CFR part 60, subpart DDDD—Emission Guidelines and Compliance Times for Commercial and Industrial Solid Waste Incineration Units;
• 40 CFR part 62, subpart IIIa—Federal Plan Requirements for Commercial and Industrial Solid Waste Incineration Units That Commenced Construction on or Before June 4, 2010, and Have Not been Modified or Reconstructed Since August 7, 2013 As discussed earlier in section VIII.A, the temporary use provisions in the CISWI EG do not directly apply to existing sources. However, following final rule promulgation, States may amend their State plans implementing 40 CFR part 60, subpart DDDD to include these temporary use provisions.

IX. Rationale for Temporary Use of CISWI Units in Disaster Recovery

A. Temporary Use of CISWI During Disaster Recovery

This rule proposes temporary use disaster recovery and emergency provisions for the Federal CISWI regulations similar to those
currently in the Federal OSWI regulations. Under this proposal, like OSWI units, CISWI units would not need to comply with
their CAA section 129 emission standards and associated requirements while they are used to combust debris as long as they
follow the conditions for these temporary use provisions. Specifically, the owners or operators of CISWI units would be allowed
to combust debris only in an area declared a State of Emergency by a local or State government or where the President, under
the authority of the Stafford Act, has declared that an emergency or a major disaster exists in the area. Under these temporary
use provisions, debris that could be combusted would be any non-hazardous material that is the remains of something that is
destroyed, broken, or discarded as a result of a disaster or emergency such as a tornado, hurricane, flood, ice storm, high
winds, or act of bioterrorism; and during the disaster recovery period, the CISWI unit would not be burning waste from normal
operations at their commercial and industrial facilities. Also, owners and/or operators would follow the notification requirements
specified in the temporary use provisions.

In addition, under the CISWI temporary use provisions, we are proposing that control devices that have been installed to comply
with CISWI NSPS, CISWI Federal plan or a State plan implementing CISWI EG would continue operation during temporary use status
unless it is not technically feasible to do so due to conditions in the disaster recovery area; (68) otherwise, these controls are already in place, and they can minimize air pollution during the disaster recovery period even
if the CISWI are excluded from CAA section 129 standards and associated requirements during that time. Examples of infeasibility
to operate include insufficient electricity to operate a control device, lack of water to operate a wet scrubber or quench,
and inability to get replacement supplies such as activated carbon or parts for maintenance.

We believe that during the disaster recovery period, CAA section 129 CISWI standards and associated requirements are not appropriate
for incinerators at commercial and industrial facilities that are burning only non-hazardous debris and only long enough to
complete the recovery tasks; during the disaster recovery period, these incinerators are not used as regular commercial and
industrial waste disposal devices, which Congress intended the CAA section 129 standards to regulate. Also, as the EPA previously
explained, “in emergency situations, quick removal of debris is of utmost importance to maintain public health and safety,
and temporary use incinerators may be best suited to dispose of debris.” (69) Quick removal without complying with CAA Section 129 standards allows for the more expedited incineration of dried debris,
which reduces the near-term likelihood of catastrophic wildfires occurring. (70) If units elect to comply with the CISWI standards, they may lose valuable time and bandwidth to incinerate debris as quickly
as possible. The EPA, therefore, elected to exclude incinerators from CAA section 129 standards when they are used on a short-term
basis to burn debris during disaster recovery, noting that such “regulation would hinder the recovery effort and this impact
would outweigh the benefits from regulation of the units.” (71) The EPA found that “this proactive approach, which addresses the terms for use of a temporary-use incinerator during declared
emergencies or disasters, is better than an approach

  that requires the EPA and others to react during or immediately after such an emergency or disaster strikes. This provision
  allows CISWI operators in a disaster region to quickly shift from existing operations to combusting only non-hazardous disaster
  debris, without the impediment of complying with the CISWI standards during temporary use. We also point out that States and
  the Federal government have specific procedures that are followed in declaring an area a State of Emergency or a major disaster
  area. Their procedures involve extensive involvement by local, State, and Federal officials to conduct a preliminary damage
  assessment, develop debris removal plans, and coordinate and manage disaster assistance activities.”

B. Temporary Use Period and Notifications

As in the OSWI regulations, we are not proposing to require any notification for temporary use of CISWI units for disaster
recovery that lasts eight weeks or less (beginning on the date the unit starts operation in response to a disaster or emergency).
This ability to start temporary use without notification during the first eight weeks would ease the burden during or immediately
after a disaster or emergency. If the CISWI unit were used for longer than eight weeks, the owner or operator would be required
to notify the Administrator in writing and request permission to continue to operate. Submitting such notification would permit
temporary use for an additional eight weeks, which is a total of 16 weeks from the date the unit started operation. The notification
would have to be submitted in writing by the date eight weeks after the temporary use incinerator starts operation and would
include the following information: the date the incinerator started operation within the boundaries of the current emergency
or disaster declaration area; identification of the disaster or emergency for which the incinerator is being used; a description
of the types of materials being burned in the incinerator; a brief description of the size and design of the unit, including
any existing control devices; the reasons the incinerator must be operated for more than eight weeks; the amount of time for
which the owner or operator requests permission to operate including the date the unit is expected to cease operation; and,
if applicable, a brief description of why the control devices are infeasible to operate due to the disaster. If the request
is for longer than 16 weeks, the owner or operator would have to cease operation of the unit or comply with applicable CISWI
regulatory requirements at the end of 16 weeks, unless the Administrator approves in writing a request to continue operation.
16 weeks will be the maximum length of time a temporary-use incinerator can operate in a given area declared a State of Emergency
or major disaster without specific permission to continue operation from the Administrator. The approval of the request to
continue operating must establish a site-specific date to cease operation. Similar to the OSWI exclusion, EPA is proposing
this approach, rather than a uniform maximum amount of time, because a case-by-case approval process allows EPA and States
to set the appropriate time limits for the specific situation.

If finalized, the proposed temporary use provisions would directly impact incinerators subject to the CISWI NSPS (40 CFR part
60, subpart CCCC) and Federal plan (40 CFR part 62, subpart IIIa) but not those subject to state plans implementing CISWI
EG (40 CFR part 60, subpart DDDD). States could then amend their State plans for existing CISWI units to incorporate this
temporary use provision.

X. Summary of Cost, Environmental, and Economic Impacts for CISWI Temporary Use Incinerators in Disaster Recovery

We are proposing the temporary use of CISWI units during a disaster or emergency, for the purposes of combusting related debris.
Facilities with CISWI units that use the disaster recovery temporary use provisions would not be subject to additional control
requirements; they would not need to meet the existing CAA section 129 requirements during this temporary use period. Therefore,
we anticipate there would not be any additional capital costs for compliance with this proposal if finalized, only annual
notification costs. As cleanup responses are necessary during and following a disaster or emergency, we anticipate that this
action would have minimal adverse environmental impacts, as the benefits of using CISWI units will outweigh the alternatives
of open burning and/or increased risk of wildfires that would degrade air quality. (72) As we are unable to quantify the number of units that would be affected by this rulemaking, we are unable to quantify the
cost savings from this action at this time.

XI. Request for Comment for CISWI Temporary Use Incinerators in Disaster Recovery

The EPA solicits comment on all aspects of this proposed action described above. Comments can be submitted to the CISWI Docket
ID No. EPA-HQ-OAR-2003-0119.

In addition to general comments on this proposed action, we are soliciting comments on the following topics. A comment reference
indicator for each specific topic is provided (e.g., Emergency-1, Emergency-2, etc.).

• Incidents of insufficient numbers of incinerators for emergency/disaster debris cleanup and the impacts on the affected communities. (Emergency-1).
• Information on the difficulty with complying with CISWI regulations during emergency/disaster debris cleanup. (Emergency-2).
• Information on State and local efforts in minimizing health impact during emergency/disaster debris cleanup. (Emergency-3).

XII. Statutory and Executive Order Reviews

Additional information about these statutes and Executive Orders can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review and Executive Order 13563: Improving Regulation and Regulatory Review

The proposed actions to consolidate the regulations for ACI burning only certain fuels and to allow for temporary use of CISWI
units during disasters or emergencies are not considered significant regulatory actions as defined in Executive Order 12866.
This proposal was therefore not submitted to the Office of Management and Budget (OMB) for review.

B. Executive Order 14192: Unleashing Prosperity Through Deregulation

This action proposing to consolidate regulations for ACI that only burn wood wastes, yard wastes, clean lumber, or any mixture
of those materials is considered an Executive Order 14192 deregulatory action because it would provide burden reduction by
simplifying compliance and some permitting requirements. This action to allow for temporary use of CISWI units is considered
an Executive Order 14192 deregulatory action because it would reduce burdens for CISWI units during emergency and disaster
recovery with the temporary use provisions.

C. Paperwork Reduction Act (PRA)

The information collection activities in this action have been submitted for approval to OMB under the PRA as discussed for
each of the relevant subpart discussed in sections XII.C.1, XII.C.2, and XII.C.3.

1. ICR for Consolidated Air Curtain Incinerators: 40 CFR Part 60, Subpart Ca

The Information Collection Request (ICR) document prepared by the EPA has been assigned the EPA ICR number 7813.01. You can
find a copy of the ICR in Docket ID No. EPA-HQ-OAR-2025-0068, and it is briefly summarized here.

The proposed rulemaking requires initial notifications and opacity tests by the owners and operators of the affected facilities.
Owners and operators would also be required to maintain records of and submit the results of opacity tests. These notifications,
reports, and records are essential in determining compliance and are required of all affected facilities subject to the subpart.
The EPA notes that most of the burden associated with this ICR is burden being transferred from existing ICRs for the subparts
that currently regulate ACI that only burn wood wastes, yard wastes, and clean lumber. The only new burden for this ICR is
associated with the initial notification of applicability for existing units.

Respondents/affected entities: New or existing air curtain incinerators that only burn wood wastes, yard wastes, and clean lumber.

Respondent's obligation to respond: Mandatory (40 CFR part 60, subpart Ca).

Estimated number of respondents: 52.

Frequency of response: Once for startup/applicability notification, annually for opacity test, as needed for disaster recovery for the clean ACI.

Total estimated burden: 1,570 hours (per year), of which the EPA estimates approximately 640 burden hours are currently associated with the CISWI
rules and 807 burden hours are currently associated with the OSWI rules. Burden is defined at 5 CFR 1320.3(b).

Total estimated cost: $537,000, of which the EPA estimates that approximately $230,000 is currently associated with the CISWI rules and $290,000
is currently associated with the OSWI rules. The annualized capital operation & maintenance costs are $156,000.

2. ICR for CISWI Temporary Use Incinerators NSPS: 40 CFR Part 60, subpart CCCC

The information collection request (ICR) documents that the EPA prepared have been assigned EPA ICR number 1926.10. You can
find a copy of the ICR in Docket ID No. EPA-HQ-OAR-2003-0119, and it is briefly summarized here. The information collection
requirements are not enforceable until OMB approves them.

This action proposes to amend the current requirements in 40 CFR part 60, subpart CCCC to allow owners and operators to temporarily
combust debris associated with disaster recovery. As part of these proposed requirements, owners and operators would submit
a notification to the Administrator whenever an incinerator is used to combust this type of debris for more than eight weeks.
There would be no other changes to the notification, recordkeeping, and reporting required in these subparts. These notifications,
reports, and records are essential in determining compliance with the applicable subpart.

Respondents/affected entities: Owners and operators of new CISWI units.

Respondent's obligation to respond: Mandatory if temporary use exceeds eight weeks (40 CFR part 60, subpart CCCC).

Estimated number of respondents: 16, of which the EPA estimates that approximately 1.6 will be subject to this proposed notification requirement annually.

Frequency of response: As needed for disaster recovery.

Total estimated burden: 2,230 hours per year for 40 CFR part 60, subpart CCCC, of which the EPA estimates approximately 3.7 hours are associated with
this notification annually. Burden is defined at 5 CFR 1320.3(b).

Total estimated cost: $1,530,000 (per year) for 40 CFR part 60, subpart CCCC, of which the EPA estimates that approximately $529 is associated with
this notification annually.

3. ICR for CISWI Temporary Use Incinerators EG: 40 CFR Part 60, Subpart DDDD and 40 CFR Part 62, Subpart IIIa

This action proposes to amend the current requirements in 40 CFR part 60, subpart DDDD and 40 CFR part 62, subpart IIIa to
allow owners and operators to temporarily combust debris associated with disaster recovery. As part of these proposed requirements,
owners and operators would submit a notification to the Administrator whenever an incinerator is used to combust this type
of debris for more than eight weeks. There would be no other changes to the notification, recordkeeping, and reporting required
in these subparts. These notifications, reports, and records are essential in determining compliance with the applicable subpart.

Respondents/affected entities: Owners and operators of existing CISWI units.

Respondent's obligation to respond: Mandatory if temporary use exceeds eight weeks (40 CFR part 60, subpart DDDD, and 40 CFR part 62, subpart IIIa).

Estimated number of respondents: 76 for 40 CFR part 60, subpart DDDD and 40 CFR part 62, subpart IIIa, of which the EPA estimates that approximately 2.7 existing
units will be subject to this proposed notification requirement annually.

Frequency of response: As needed for disaster recovery.

Total estimated burden: 8,510 hours per year for 40 CFR part 60, subpart DDDD and 40 CFR part 62, subpart IIIa, of which the EPA estimates approximately
6.2 burden hours are associated with this notification annually. Burden is defined at 5 CFR 1320.3(b).

Total estimated cost: $13,500,000 (per year) for 40 CFR part 60, subpart DDDD and 40 CFR part 62, subpart IIIa, of which the EPA estimates that
approximately $893 is associated with this notification annually.

An agency may not conduct or sponsor, and a person is not required to respond to a collection of information unless it displays
a currently valid OMB control number. The OMB control numbers for EPA's regulations in 40 CFR part 51 are listed in 40 CFR
part 9. Submit your comments on the agency's need for this information, the accuracy of the provided burden estimates, and
any suggested methods for minimizing respondent burden to the EPA using the docket identified at the beginning of this rule.
The EPA will respond to any ICR related comments in the final rule. You may also send your ICR-related comments to OMB's Office
of Information and Regulatory using the interface at www.reginfo.gov/public/doPRAMain. Find this particular information collection by selecting “Currently under Review-Open for Public Comments” or by using the
search function. OMB must receive comments no later than April 20, 2026.

D. Regulatory Flexibility Act (RFA)

I certify that these proposed actions will not have a significant economic impact on a substantial number of small entities
under the RFA. In making this determination, EPA concludes that the impact of concern for this rulemaking is any significant
adverse economic impact on small entities, and that the agency is certifying that this rulemaking will not have a significant
economic

  impact on a substantial number of small entities because the rule relieves regulatory burden on the small entities subject
  to the rule. This Consolidated ACI proposed action will impose monitoring, recordkeeping and reporting requirements that currently
  exist in the respective rules for OSWI, CISWI, LMWC and SMWC units. We only anticipate the additional costs of the initial
  notification requirements. The EPA has a provided a memo in the docket for this action titled, “Economic Impact and Small
  Business Analysis for the Consolidated Air Curtain Incinerators (ACI) and Temporary Use of Commercial Industrial Solid Waste
  Incinerators (CISWI) Proposed Rule.” For the CISWI Temporary Use Incinerator Actions, there are no additional control requirements
  and thereby no additional compliance costs. Therefore, we conclude that this action will relieve regulatory burden for all
  directly regulated small entities.

E. Unfunded Mandates Reform Act (UMRA)

These proposed actions do not contain unfunded mandates of $100 million or more as described in the UMRA, 2 U.S.C. 1531-1538,
and does not significantly or uniquely affect small governments. This action imposes no enforceable duty on any State, local
or Tribal governments or the private sector.

F. Executive Order 13132: Federalism

These proposed actions do not have federalism implications. The actions will not have substantial direct effects on the states,
on the relationship between the national government and the states, or on the distribution of power and responsibilities among
the various levels of government.

G. Executive Order 13175: Consultation and Coordination With Indian Tribal Governments

These proposed do not have Tribal implications. It will neither impose substantial direct compliance costs on federally recognized
Tribal governments, nor preempt Tribal law.

H. Executive Order 13045: Protection of Children From Environmental Health Risks and Safety Risks

EPA interprets Executive Order 13045 as applying only to those regulatory actions that concern environmental health or safety
risks that EPA has reason to believe may disproportionately affect children, per the definition of “covered regulatory action”
in section 2-202 of the Executive Order.

The proposed actions are not subject to Executive Order 13045 because it does not concern an environmental health risk or
safety risk. Since this action does not concern human health, EPA's Policy on Children's Health also does not apply.

I. Executive Order 13211: Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, or Use

These proposed are not “significant energy actions” because they are not likely to have a significant adverse effect on the
supply, distribution, or use of energy. Further, we have concluded that this action is not likely to have adverse energy effects
because it does not involve energy supply, distribution, or use of energy.

J. National Technology Transfer and Advancement Act (NTTAA) and 1 CFR Part 51

This notice of proposed rulemaking involves technical standards for ACI that only burn wood wastes, yard wastes, and clean
lumber. Therefore, the EPA conducted searches through the Enhanced National Standards System Network Database managed by the
American National Standards Institute (ANSI) to determine if there are voluntary consensus standards (VCS) that are relevant
to this action. We conducted searches for EPA Method 9 of 40 CFR part 60, appendix A. During the search, if the title or abstract
(if provided) of the VCS described technical sampling and analytical procedures that are similar to the EPA's reference method,
the EPA considered it as a potential equivalent method. All potential standards were reviewed to determine the practicality
of the VCS for these rules. This review requires significant method validation data which meet the requirements of EPA Method
301 for accepting alternative methods or scientific, engineering and policy equivalence to procedures in the EPA reference
methods. The EPA may reconsider determinations of impracticality when additional information is available for particular VCS.
ASTM D7520-16, Standard Test Method for Determining the Opacity of a Plume in the Outdoor Ambient Atmosphere, approved April
1, 2016, describes how digital imagery and associated hardware and software is used to determine the opacity of a plume. The
EPA will allow the voluntary consensus standard ASTM D7520-16, as an acceptable alternative to EPA Method 9 with the following
caveats:

1. During the digital camera opacity technique (DCOT) certification procedure outlined in section 9.2 of ASTM D7520-16, you
   (the operator of the regulated unit) or the DCOT vendor must present the plumes in front of various backgrounds of color and
   contrast representing conditions anticipated during field use such as blue sky, trees, and mixed backgrounds (clouds and a
   sparse tree stand).

2. You must also have standard operating procedures in place including daily or other frequency quality checks to ensure the
   equipment is within manufacturing specifications as outlined in Section 8.1 of ASTM D7520-16.

3. You must follow the recordkeeping procedures outlined in section 63.10(b)(1) for the DCOT certification, compliance report,
   data sheets, and all raw unaltered JPEGs used for opacity and certification determination.

4. You or the DCOT vendor must have a minimum of four (4) independent technology users apply the software to determine the
   visible opacity of the 300 certification plumes. For each set of 25 plumes, the user may not exceed 15 percent opacity of
   anyone reading and the average error must not exceed 7.5 percent opacity.5. Use of this approved alternative does not provide
   or imply a certification or validation of any vendor's hardware or software. The onus to maintain and verify the certification
   and training of the DCOT camera, software and operator in accordance with ASTM D7520-16 and these requirements is on the facility,
   DCOT operator, and DCOT vendor. This method is available at ASTM International, 1850 M Street NW, Suite 1030, Washington,
   DC 20036. See www.astm.org. The standard is available to everyone at a cost determined by ASTM. The cost of obtaining this method is not a significant
   financial burden, making the method reasonably available. Additional information for the VCS search and determinations can
   be found in the memorandum, Voluntary Consensus Standard Results for Consolidation of standards for air curtain incinerators
   that only burn wood wastes, yard wastes, and clean lumber, which is available in the docket for this action (Docket ID No.
   EPA-HQ-OAR-2025-0068).

Under 40 CFR 60.8(b) and 60.13(i) of subpart A of the General Provisions, a source may apply to the EPA to use alternative
test methods or alternative monitoring requirements in place of any required testing methods, performance

  specifications or procedures in the final rule or any amendments.

Lee Zeldin Administrator. [FR Doc. 2026-05491 Filed 3-19-26; 8:45 am] BILLING CODE 6560-50-P

Footnotes

(1) See, e.g., 40 CFR 60.2977.

(2) See, e.g., 40 CFR 60.2977.

(3) 42 U.S.C. 7429(a)(1)(A) (citing 42 U.S.C. 7411).

(4) Id. 7429(g)(1), (g)(1)(C).

(5) The proposed removal would not cover ACI for which such removal was finalized in the 2026 LMWC new source performance standards
and emissions. 91 FR 11802 (Mar. 10, 2026).

(6) 89 FR 27392 (Apr. 17, 2024), as amended November 04, 2024.

(7) 91 FR 11802 (Mar. 10, 2026).

(8) See, e.g., FDA v. Wages & White Lion Invs., L.L.C., 145 S. Ct. 898, 917 (2025); Encino Motorcars v. Navarro, 579 U.S. 211, 221 (2016); FCC v. Fox Television Stations, Inc., 556 U.S. 502, 515 (2009).

(9) 42 U.S.C. 7429(e).

(10) 42 U.S.C. 7661a(a).

(11) See e.g., 76 FR 15741 (Mar. 21, 2011).

(12) Id.

(13) 42 U.S.C. 7661a(a).

(14) 40 CFR 60.2966(b); see also 40 CFR 70.3(a)(1) (requiring title V permitting for any “major source”); 40 CFR 70.2 (defining a “major source” under title
V).

(15) See 91 FR 11802 (Mar. 10, 2026).

(16) See, e.g., 40 CFR 60.2242, 62.15020(k).

(17) 89 FR 27392 (Apr. 17, 2024).

(18) See 91 FR 11802 (Mar. 10, 2026).

(19) 40 CFR 60.51b, 60.1940, 60.2875; Table 1 of this document.

(20) 40 CFR 60.2977, 60.3078; see also Table 1 of this document.

(21) See, e.g., 40 CFR 60.1920, 60.2860, 60.56b, 60.3066; Table 1 of this document.

(22) See, e.g., 65 FR 76355 (Dec. 6, 2000); 60 FR 65419 (Dec. 19, 1995); 84 FR 15853 (Apr. 16, 2019), 70 FR 74892 (Dec. 16, 2005).

(23) See, e.g., NSPS CCCC (40 CFR 60.2125(i)).

(24) See Docket ID No. EPA-HQ-OAR-2003-0119.

(25) See NSPS Eb (40 CFR 60.58b(l)(3)), NSPS CCCC (40 CFR 60.2255(c)), and NSPS EEEE (40 CFR 60.2972(c)).

(26) See NSPS AAAA (40 CFR 60.1445(a)).

(27) See NSPS EEEE (40 CFR 60.2972(d)).

(28) See NSPS Eb (40 CFR 60.58b(l)(2)), NSPS CCCC (40 CFR 60.2255(b)), and NSPS EEEE (40 CFR 60.2972(b)), which reference 40 CFR 60.8
for conducting the initial performance test and NSPS AAAA, which states the same timeframe in 40 CFR 60.1445(a).

(29) See 40 CFR 60.3068.

(30) See 40 CFR 60.2870.

(31) See 40 CFR 60.59b(e) and 60.1930, respectively.

(32) CAA section 502(a) provides that the EPA cannot exempt major sources from title V by rule. See 42 U.S.C. 7661a(a); 40 CFR 70.3(b)(1). This proposed rule also would not affect title V applicability to any ACI currently
subject to title V for other reasons, as provided in CAA section 502(a) and 40 CFR 70.3(a).

(33) See 89 FR 27392 (Apr. 17, 2024).

(34) See 91 FR 11802 (Mar. 10, 2026).

(35) See 76 FR 15741 (Mar. 21, 2011).

(36) See 60 FR 65387, 65425 (Dec. 19, 1995).

(37) See 59 FR 48198, 48211 (Sept. 20, 1994).

(38) See id. at 48223.

(39) 65 FR 75338 (Dec. 1, 2000).

(40) 76 FR 15704, 15741 (Mar. 21, 2011); 84 FR 15846, 15851 (Apr. 16, 2019).

(41) 89 FR 27392 (Apr. 17, 2024); see also 89 FR 89928 (Nov. 14, 2024) (technical correction).

(42) 89 FR 4243 (Jan. 23, 2024).

(43) 70 FR 75320, 75323 (Dec. 19, 2005); see U.S. Sugar Corp. v. EPA, 830 F.3d 579, 647 (D.C. Cir. 2016).

(44) See, e.g., 70 FR 75323 (Dec.19, 2005).

(45) See 57 FR 32250, 32251 (July 21, 1992).

(46) 42 U.S.C. 7661c(c); see also 40 CFR 70.6(c)(1).

(47) See, e.g., South Carolina title V fees: https://des.sc.gov/programs/bureau-air-quality/annual-fees-title-v-sources; Virginia title V fees; https://www.deq.virginia.gov/laws-regulations/air/fees-under-the-air-pollution-control-law; Florida title V fees: https://floridadep.gov/air/permitting-compliance/content/title-v-fees; Oregon title V fees: https://www.oregon.gov/deq/aq/aqpermits/pages/tvrule.aspx.

(48) Also, as explained in the 2024 final rule removing title V permitting requirement from OSWI section 129 regulations, “the
EPA has received feedback from several States indicating that the title V permits are unnecessarily burdensome and expensive
for States to maintain for these ACIs.” 89 FR 27394 (Apr. 17, 2024).

(49) See, e.g., 89 FR 27392, 27394 (Apr. 17, 2024).

(50) 70 FR 74876 and 74877 (Dec. 16, 2005).

(51) 88 FR 36524 (June 5, 2023).

(52) 70 FR 74870 (Dec. 16, 2005).

(53) As used in this notice, the term “CISWI” refers to this collection of Federal regulations and not incinerators as defined
by the term “CISWI” in these regulations, and the term “CISWI units” refers to incinerators subject to any one of these regulations.

(54) CAA section 129(a)(1)(A), 42 U.S.C. 7429(a)(1)(A).

(55) 70 FR 74870, 74875 (Dec. 16, 2005).

(56) Id. at 74875.

(57) 70 FR 74870 (Dec. 16, 2005).

(58) OSWI NSPS (40 CFR 60.2969) and OSWI EG (40 CFR 60.3061).

(59) Id.

(60) Abraczinskas, M. (2024). Request for Relief Concerning Air Curtain Incinerator Use in the State of North Carolina. https://www.deq.nc.gov/media/46541/download?attachment.

(61) 70 FR 74875, 74879 (Dec. 16, 2005).

(62) 70 FR 74870 (Dec. 16, 2005).

(63) Executive Order 14181, Emergency Measures to Provide Water Resources in California and Improve Disaster Response in Certain
Areas, 90 FR 8747 (Jan. 24, 2025).

(64) Moore, A. Hurricane Helene's Aftermath Fuels Heightened Wildfire Risk in Western North Carolina (2025). https://cnr.ncsu.edu/staging/2025/11/04/hurricane-helenes-aftermath-fuels-heightened-wildfire-risk-in-western-north-carolina/.

(65) U.S. EPA. No Action Assurance for the Use of Air Curtain Incinerators to Manage Debris Caused By Hurricane Helene in North
Carolina (2024), https://www.deq.nc.gov/media/46792/download?attachment.

(66) Id.

(67) Id.

(68) In promulgating the temporary use provisions in the OSWI rules, the EPA recognized that there may be instances where it
is not technically feasible to operate a control device through the entire duration of a disaster recovery period. (70 FR
74880; Dec. 16, 2005). Likewise, in this rule, the EPA is requiring that existing controls continue to operate during the
temporary use period if technically feasible, thereby acknowledging potential operational issues during such period but minimizing
emissions where there are not such issues.

(69) 70 FR 74879, (Dec. 16, 2005).

(70) U.S. EPA. No Action Assurance for the Use of Air Curtain Incinerators to Manage Debris Caused By Hurricane Helene in North
Carolina (2024), https://www.deq.nc.gov/media/46792/download?attachment.

(71) 70 FR 74879, (Dec. 16, 2005).

(72) U.S. EPA, No Action Assurance for the Use of Air Curtain Incinerators to Manage Debris Caused by Hurricane Helene in North
Carolina (2024). https://www.deq.nc.gov/media/46792/download?attachment.

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