SCAQMD Rule 1157 – Particulate Standards for Aggregate and Related Operations

South Coast Air Quality Management District (SCAQMD) of California adopted Rule 1157 in 2005 and amended it in 2008, with the purpose of reducing PM₁₀ emissions from aggregate and related operations. The rule defines “aggregate operations” as operations that produce sand, gravel, crushed stone, and quarried rocks.

Performance Standards

Rule 1157 establishes the following general performance standards for aggregate operations (Visible Emissions Performance Standards):

• Fugitive dust cannot exceed 20% opacity, averaged over 12 consecutive readings (SCAQMD Method 9B).
• Fugitive dust cannot exceed 50% opacity, averaged five consecutive readings (SCAQMD Method 9B).
• Visible dust plumes cannot extend more than 100 feet from the source.

In addition to the visible emissions limits stated above, SCAQMD sets dust-control rules for equipment, storage piles, and internal roads. Key requirements include:

• Spills: material spills must be moved away from internal roads with dust and operators must apply dust suppression and install gravel pads.
• Loading, Unloading, and Transferring: dust control methods shall be used when loading, unloading, and transferring materials
• Conveyors: dust suppressants or other dust control methods shall be used at the conveyor
• Crushing Equipment: crushing activities shall be controlled by baghouses, dust suppressants, or other dust control methods to achieve the Visible Emissions Performance Standards.
• Screening Equipment: outdoor screening activities shall use enclosed screening equipment that is equipped with a baghouse. Alternatively, dust suppressants or other dust control methods can be used to achieve the Visible Emissions Performance Standards.
• Storage Piles: the entire surface area of open storage piles shall be maintained in a stabilized condition. Alternatively, materials can be stored in a silo or bunker. Dust suppressants shall be reapplied after loading or unloading activities. If piles are located within 300 feet of off-site occupied buildings, they may not be higher than eight feet high.
• Internal Roads:
  • Unpaved Haul Roads: facilities must apply chemical stabilizers on unpaved haul roads and post signs at both ends of the unpaved haul roads stating that haul trucks shall use these roads unless they are traveling to the maintenance areas.
  • Unpaved Non-Haul Roads: facilities must apply chemical stabilizers or a gravel pad to unpaved non-haul roads and parking and staging areas.
  • Paved Roads:
    • Facilities with a minimum of 60 aggregate and/or mixer trucks exiting the facility each day shall sweep paved roads with a street sweeper by the end of each production work shift.
    • Facilities with less than 60 trucks exiting the facility each day shall sweep paved roads by the end of every other workday. Water shall be applied on days when the paved roads are not swept.
  • Track-Out: Unless exempt from the Rule, facilities shall install a rumble grate, wheel washer, or a truck washer.

Recordkeeping

The Rule requires that facilities keep certain records on-site for three years (non-Title V) or five years (Title V). Examples include records of watering and sweeping schedules for internal paved roads, aggregate and/or mixer trucks exiting the facility, and supporting documentation if the facility is seeking certain exemptions from the Rule.

Test Methods

To maintain compliance with requirements of the Rule, facilities must utilize SCAQMD Opacity Test Method No. 9B and The Stabilized Surface Test Method included in the SCAQMD Rule 403 Implementation Handbook.

Additional Requirements triggered by recurrent violation

Facilities located near communities face stricter requirements after repeated non-compliance with Rule 1157:

• If a facility is located within 500 meters of residencies or other sensitive receptors; and,
• The facility received three more validated Notices of Violation (NOV) within 12 months for causing or allowing fugitive dust emissions to exceed the Visible Emissions Performance Standards

The operations must submit an emissions reduction plan to the Executive Officer within 30 days of the third notice of violation. The plan must propose additional emissions control measures intended to remedy the cause of the recurring non-compliance for implementation as soon as practical. If a plan is disapproved, the facility shall submit a revised plan within 30 days notice of disapproval.

Exemptions

There are several activities and conditions that are exempt from certain requirements of the Rule. For example, during instances of high winds, facilities may be exempt from meeting the Performance Standards. Empty haul trucks traveling to and from maintenance areas are exempt from the requirement to use internal unpaved haul roads if they travel on internal unpaved non-haul roads. Truck trimming areas may be exempt from requirements to use a dust suppressant.

There are several types of facilities that do not need to install and operate a wheel washer (e.g., facilities that pave a minimum of ¼ mile from the rumble grate to the facility exit leading to a paved public road).

Alternative Control Options

Instead of using dust suppressants to comply with the Rule, a facility may request approval from the Executive Officer and the U.S. Environmental Protection Agency for a plan for achieving the Performance Standards through alternative control measures.

How ALL4 Can Help

As of September 2025, SCAQMD is amending Rule 1157. Stay tuned to ALL4’s 4 the Record series for updates on this Rule and other AQMD changes that could affect your facility.

Rule 1157 carries strict dust control requirements and violations can quickly turn into costly notices and mandatory corrective action plans. Don’t wait for enforcement to catch you off guard. Our Rancho Cucamonga team is ready to review your operations, spot compliance risks, and help you put practical solutions in place. Please reach out to Michael McHale (mmchale@all4inc.com) or Olivia Pehanick (opehanick@all4inc.com) today to talk about Rule 1157 and what it means for your facility.

U.S. EPA’s Proposed Reconsideration of the GHGRP

On September 16, 2025 the United States Environmental Protection Agency (U.S. EPA) published a proposed rule to Reconsider the Greenhouse Gas (GHG) Reporting Program (GHGRP) under Docket No. EPA-HQ-OAR-2025-0186. The proposed rule will remove most of the reporting requirements for almost all source categories including natural gas distribution industry segments under 40 CFR Part 98, Subpart W – Petroleum and Natural Gas Systems (Subpart W), then suspend all other reporting requirements under Subpart W. This coincides with the reconsideration of the 2009 Endangerment Finding, which classified GHG emissions as a threat to human health and welfare.

What Is the Federal GHGRP?

The Federal GHGRP was enacted in 2010 under 40 CFR Part 98 as part of the Clean Air Act (CAA). This reporting program requires manufacturing industries that emitted over 25,000 metric tons of carbon dioxide equivalent (MT CO₂e) annually or specific industries to report their direct GHG emissions from the facility on an annual basis. The emission from these more than 8,000 covered facilities accounts for over 50% of the United States’ total GHG emissions. The data from the GHGRP is used in the United States’ GHG inventory report each year, which is used for the country’s GHG reporting obligations under international treaties like the United Nations Framework Convention on Climate Change (UNFCCC) and the Paris Agreement. It is unknown how the proposed repeal will affect the status of the United States under international climate change treaties.

What Is Changing with This Proposal?

In short, 46 subparts of 40 CFR Part 98 would be removed entirely, and Subpart W would be partially removed. The following subparts are proposed to be permanently removed from the GHGRP:

• C (General Stationary Fuel Combustion Sources)
• D (Electricity Generation)
• E (Adipic Acid Production)
• F (Aluminum Production)
• G (Ammonia Manufacturing)
• H (Cement Production)
• I (Electronics Manufacturing)
• K (Ferroalloy Production)
• L (Fluorinated Gas Production)
• N (Glass Production)
• O (HCFC–22 Production and HFC–23 Destruction)
• P (Hydrogen Production)
• Q (Iron and Steel Production)
• R (Lead Production)
• S (Lime Manufacturing)
• T (Magnesium Production)
• U (Miscellaneous Uses of Carbonate)
• V (Nitric Acid Production)
• W (Petroleum and Natural Gas Systems – natural gas distribution industry segment only)
• X (Petrochemical Production)
• Y (Petroleum Refineries)
• Z (Phosphoric Acid Production)
• AA (Pulp and Paper Manufacturing)
• BB (Silicon Carbide Production)
• CC (Soda Ash Manufacturing)
• DD (Electrical Transmission and Distribution Equipment Use)
• EE (Titanium Dioxide Production)
• FF (Underground Coal Mines)
• GG (Zinc Production)
• HH (Municipal Solid Waste Landfills)
• II (Industrial Wastewater Treatment)
• JJ (Manure Management)
• LL (Suppliers of Coal-based Liquid Fuels)
• MM (Suppliers of Petroleum Products)
• NN (Suppliers of Natural Gas and Natural Gas Liquids)
• OO (Suppliers of Industrial Greenhouse Gases)
• PP (Suppliers of Carbon Dioxide)
• QQ (Importers and Exporters of Fluorinated Greenhouse Gases Contained in Pre-Charged Equipment or Closed-Cell Foams)
• RR (Geologic Sequestration of Carbon Dioxide)
• SS (Electrical Equipment Manufacture or Refurbishment)
• TT (Industrial Waste Landfills)
• UU (Injection of Carbon Dioxide)
• VV (Geologic Sequestration of Carbon Dioxide with Enhanced Oil Recovery Using ISO 27916)
• WW (Coke Calciners)
• XX (Calcium Carbide Producers)
• YY (Caprolactam, Glyoxal, and Glyoxylic Acid Production)
• ZZ (Ceramics Manufacturing)

The reporting requirements for Subpart W, as established by the Inflation Reduction Act (IRA), cannot be entirely repealed due to the provisions set forth in the legislation. Therefore, U.S. EPA proposed to delay reporting of the following industry segments under Subpart W until reporting year (RY) 2034:

• Onshore petroleum and natural gas production
• Offshore petroleum and natural gas production
• Onshore natural gas processing
• Onshore natural gas transmission compression
• Onshore petroleum and natural gas gathering and boosting
• Onshore natural gas transmission pipelines
• Underground natural gas storage
• Liquefied natural gas (LNG) storage
• LNG import and export equipment

U.S. EPA is also proposing to extend the RY 2025 deadline from March 31, 2026 to June 10, 2026 to allow more time for the finalization of the proposed rule.

How Does This Affect My Facility?

There is a high potential that the repeal of the GHGRP will be in effect prior to the reporting deadline for RY 2025. If the proposed amendments are finalized, your facility will no longer need to comply with the recordkeeping and reporting requirements under the GHGRP going forward. Although for the time being, we recommend that your facility keeps up with all recordkeeping and reporting requirements outlined in the rule until the reconsideration is final.

Even though the Federal GHGRP may be repealed, it is important to monitor state GHG reporting requirements and understand their applicability to your facility. At present, California Oregon, and Washington have established GHG reporting requirements, with New York expected to implement similar regulations in the near future.

What Is Next?

We suspect U.S. EPA will move on this quickly, but we need to first see the decision on the 2009 Endangerment Findings. Nonetheless, it is anticipated that U.S. EPA’s final decision will be subject to litigation.

U.S. EPA is accepting public comments on the proposed rule through November 2, 2025, under Docket ID No. EPA-HQ-OAR-2025-0186. Comments can be submitted at https://www.regulations.gov/ or by mail. U.S. EPA is also holding a virtual public hearing on October 1, 2025.

Need Help Understanding How this Affects You?

If you are wondering how this interim final rule will affect your facility directly, please reach out to your ALL4 project manager or contact Louise Shaffer at lshaffer@all4inc.com.

How To Develop A Regulatory Compliant QA/QC Program For Your CMS – Part 2

In Part 1 of this 4 The Record article series, the terminology for Quality Assurance (QA) and Quality Control (QC) was defined and discussed. QA activities, such as cylinder gas audits (CGAs) and relative accuracy test audits (RATAs), ensure quality control activities are adequately performed. QC activities, which include activities such as daily calibration drift (CD) tests and maintenance, ensure a reproducible quality product. QC activities are inherently part of a facility’s QA, as QC activities are performed to ensure data continues to accurately represent emissions at the facility. The implementation of a QC Program is one of the ways a facility complies with QA requirements.

Regulatory Requirements

Various air quality regulations require use of continuous monitoring systems (CMS) to demonstrate or indicate compliance with applicable emissions standards and/or operating limits. The most common examples include 40 CFR Part 60, Part 63, and Part 75; these regulations also contain QA and QC requirements for CMS. This 4 The Record article, Part 2 of the series, focuses on the requirements of a CMS QC Program (also referred to as “QA/QC Program” in 40 CFR Part 75 and “Site Specific Monitoring Plan” in 40 CFR Part 63). As an example, 40 CFR Part 60, Appendix F is titled “Quality Assurance Procedures,” and each procedure in Appendix F outlines quality assurance requirements for different types of monitoring systems [e.g., Appendix F, Procedure 1 (P1) is titled, “Quality Assurance Requirements for Gas Continuous Emission Monitoring Systems Used for Compliance Determination”]. P1 requires the development and implementation of a QC Program. Note that there is no direct requirement in P1 for a CMS QA/QC Plan. However, P1 requires written procedures that describe in detail, complete, step-by-step procedures and operations for certain QA and QC activities. Those procedures (in addition to other items identified in QA/QC programs) are the basis for our QA/QC Plan.

Having a QA/QC Plan alone does not satisfy the requirement. The requirement is to “develop and implement a QC program.” The QA/QC Plan serves to satisfy the “written procedures” part of the requirement. To fully satisfy the requirement of a “QC program” the specified QA and QC activities must be developed and implemented.

QC Program Success

Let’s explore what success looks like when developing and implementing a QC program; at the end of the day that is the regulatory requirement. To do that, we ask ourselves what the measurement objectives of the program are, and what the QA objectives are. In this case, we are tasked with evaluating the quality of data collected by monitoring systems used in determining compliance with emissions standards on a continuous basis. At the same time, we are tasked with minimizing the time during which the monitoring systems are malfunctioning (not producing representative data) or out-of-control (as defined by the applicable regulations). The measure of success for a QC program could be overall amount of acceptable data, or it could be the amount of compliant results. Minimal downtime equals a successful QC program, right? Or maybe you’ve been lucky, and your QC program has not yet been challenged with recurring corrective maintenance activities, frequent excess calibration drifts, etc. To assess your CMS QC program, review the CMS downtime for the last year. Regardless of the amount of CMS downtime reported, look at the individual events. Was the downtime a result of the same root cause? Was the root cause even determined? What actions were taken to minimize the CMS downtime events from recurring? What interaction was there between environmental personnel and instrumentation technicians for the CMS downtime events? If your CMS downtime reporting feels like an exercise completed with the only goal to submit the CMS downtime report on time, then it is time to reassess your CMS QC program. If you’re still wondering about the effectiveness of your QA/QC program, ask when was the last time your environmental, operations, and instrumentation personnel were trained on the data quality objectives for CMS.

The following paragraphs discuss examples of QA and QC activities required by P1. Note that the QA and QC activities as part of 40 CFR Part 60, Appendix F, Procedure 3 (P3) and Part 75 have similar requirements to meet the data quality objectives of those rules.

Calibration Procedures

A QA/QC Program is required to contain and implement procedures for calibrations. Section 4 of P1 describes the requirements for CD Assessments. Owners and operators of sources monitored by CMS must quantify CD at two different concentration values (known as the zero or low-level calibration and the high-level calibration) at approximately every 24 hours. During a CD Test, a reference gas containing a known pollutant is introduced to the system, passes through the system, is read by the analyzer, and is compared to the known concentration of the pollutant using the CD equation specified in Appendix B. If the drift on either level exceeds two times the applicable drift specification for five consecutive days, or the drift on either level exceeds four times the applicable drift specification at any time, the CMS is out of control, and corrective action must be taken.

Even if you have the written procedures for the CD task itself, does your QC program provide structure for implementing procedures, include preventative measures to predict CMS failures, or describe the process for corrective actions (especially on weekends and holidays)? If not, then your CMS could be at risk for excessive downtime due to CMS malfunctions that are not repaired promptly.

Preventive and Corrective Maintenance

Procedures for preventive and corrective maintenance are required to be maintained within the QA/QC Plan and implemented when necessary. Preventive maintenance is maintenance performed on the CMS on a regular basis with the intention of minimizing CMS malfunctions. It should be performed in accordance with standard industry practices and the manufacturer’s recommendations. Preventive maintenance should be tracked and recorded as part of the QA/QC Program, and a list of spare parts should be documented in the QA/QC Plan, or somewhere else on-site (and, of course, stocked on-site). Corrective maintenance is maintenance that occurs as a result of a CMS malfunction. It is performed as a reaction to a CMS malfunction, whereas preventive maintenance is a proactive measure. Similar to preventive maintenance, corrective maintenance should be performed in accordance with standard industry practices and the manufacturer’s recommendations. It should be tracked and recorded as part of the QA/QC Program. In addition, common maintenance activities and their procedures, as well as follow-up quality assurance activities, should be recorded in the QA/QC Plan.

If the CMS breaks, you fix it. When was the last time your CMS (from probe tip to data acquisition) was evaluated for remaining expected life? Are spare parts available for your CMS? Is the vendor still supporting your CMS make and model? Obsolescence planning for CMS is an important part of a good QC Program. Replace your CMS on your terms, not in response to a catastrophic failure.

Data Recording, Calculations, and Reporting

Procedures for recording, calculating, and reporting data must be documented in the QA/QC Plan and implemented. Data is often recorded in a data acquisition and handling system (DAHS). The DAHS can also calculate a result in terms of the emissions standard from measured data. Although a DAHS is not required by name in 40 CFR Part 60 Appendix B or Appendix F, or 40 CFR Part 75, it is a helpful tool for implementing data recording, calculations, and generating reports. However, at a minimum, data calculations, applicable averaging periods, and reporting procedures must be described in your QA/QC Plan and be properly implemented.

What magic does your “black box” do? Knowing how your data is managed is a regulatory requirement and manages risk. From measurement, your data’s journey can involve many different elements (PLCs, data loggers, DCS, PI, DAHS, etc.). Understanding what each element does to your data is equally important to how the calculations are performed.

Accuracy Audit Procedures

Procedures for quarterly and annual audits are required to be documented and implemented. For gas continuous emissions monitoring systems (CEMS) subject to 40 CFR Part 60 Appendix F, quarterly audits are called CGAs and are specified in P1. During a CGA, an analyzer is challenged three times with an audit gas of known concentrations at two points within the concentration ranges. The average of the three responses for each audit point is used to determine accuracy. If the accuracy does not meet the passing criteria specified in P1, the CGA fails, corrective maintenance must be performed, and an audit must be performed again. The annual audit, called a RATA by P1, is required to be conducted at least once every four calendar quarters, and as part of initial certification procedures. A RATA is a comparison of the CEMS results to a reference method. They must be performed in accordance with the reference method in Appendix A to 40 CFR Part 60 corresponding to the pollutant being tested. If the accuracy does not meet the passing criteria specified in the applicable performance specification in Appendix B, the RATA fails, corrective maintenance must be performed, and the RATA must be performed again.

Conclusion

When developing or evaluating a QC Program at your facility, it is important to remember the following:

• A QC Program cannot be implemented without QA and QC activities.
• A QA/QC Plan alone is not sufficient to meet the requirement to “develop and implement a QC program.” The implementation and completion of the activities outlined in the QA/QC Plan must also occur.
• Minimal downtime does not always indicate a successful QC Program. It is important to identify the root cause of downtime, take action to minimize future downtime, and train facility personnel on data quality objectives for CMS.

Part 3 of this series will address the nuances in the development of a QC Program. For example, what is meant by “detail”, “complete”, or “step-by-step”? ALL4’s CMS-focused team is committed to publishing several follow-up blogs for QA/QC Programs for CMS throughout 2025. If you have any CMS-related questions, need help assessing or updating a CMS QA/QC Program, or want to suggest additional topics please email Eric Swisher (eswisher@all4inc.com) or Corey Weiss (cweiss@all4inc.com).

Air Quality Permitting Data Centers in Pennsylvania

The construction and air permitting of data centers continues to be a growing industry worldwide. Each country and state has their own set of requirements for the construction and permitting process. Currently, Pennsylvania is a hotbed for data center growth given the recent news regarding 90 billion dollars of investment in data center construction. A critical component of meeting construction schedules and avoiding costly delays is obtaining the air permit required to start project-related construction. Typical aspects of air permitting include preparing an air permit strategy to evaluate construction phases and proposed equipment, collaboration with the regulatory agency, and evaluation of environmental justice considerations surrounding the development and establishment of data centers.

ALL4 Air Quality experts review the process of strategizing for and obtaining an air quality permit in Pennsylvania in a data center-specific white paper.

This white paper reviews:

• Emissions calculations and the nuance pertinent to data centers,
• Types of air permits available to data center companies and associated timelines,
• Process of identifying the Best Available Technology (BAT),
• Environmental justice process in Pennsylvania, and,
• Best practices for permitting data centers.

If you have any questions or would like assistance in evaluating how your facility may be subject to air permitting requirements as a data center, please reach out to Merritt McGlynn at mmcglynn@all4inc.com, Sharon Sadler at ssadler@all4inc.com, and Colleen Nagel at cnagel@all4inc.com. ALL4 will continue to track updates to additional guidance or rulemaking regarding the construction and permitting requirements for data centers not only in Pennsylvania, but for other U.S. states; check out our website routinely or subscribe for our newsletter to stay up-to-date.

U.S. EPA Extends Compliance Deadlines for Oil and Natural Gas Sector

On July 31, 2025, the United States Environmental Protection Agency (U.S. EPA) issued an interim final rule to extend compliance deadlines established for crude oil and natural gas facilities that are subject to the provisions of 40 Code of Federal Regulations (CFR) Part 60, Subpart OOOOb – Standards for Performance for Crude Oil and Natural Gas Facilities for Which Construction, Modification, or Reconstruction Commenced After December 6, 2022 (Subpart OOOOb). With these changes, U.S. EPA is amending compliance deadlines and timeframes based on multiple petitions for reconsideration, allowing affected facilities additional time to meet the compliance deadlines under Subpart OOOOb. Likewise, U.S. EPA has determined that multiple states are still in the early stages of developing state plans under 40 CFR Part 60, Subpart OOOOc – Emissions Guidelines for Greenhouse Gas Emissions from Existing Crude Oil and Natural Gas Facilities (Subpart OOOOc). U.S. EPA has received many inquiries from state regulatory agencies regarding extensions to the state plan submission requirements under Subpart OOOOc. Therefore, U.S. EPA has extended the state plan submission deadline for Subpart OOOOc, allowing more time for states to submit their respective plans.

These extensions come on the heels of U.S. EPA’s March 12, 2025 announcement that they would reconsider specific provisions of Subparts OOOOb and OOOOc pertaining to vent gas net heating value (NHV) monitoring for flares and enclosed combustion devices and temporary flaring provisions for associated gas under certain conditions. According to the recently released Spring 2025 Unified Agenda, U.S. EPA plans to issue a proposed reconsideration of the subparts in November 2025 with a final rule in July 2026.

Key Deadline Extensions under Subpart OOOOb

U.S. EPA published 40 CFR Part 60 Subpart OOOOb, which finalized air quality regulations for greenhouse gas (GHG) and volatile organic compound (VOC) emissions from affected sources constructed, modified, or reconstructed after December 6, 2022. Affected sources regulated under Subpart OOOOb include wells, centrifugal compressors, reciprocating compressors, process controllers, storage vessels, process units, sweetening units, pumps, and fugitive emissions components at a well site, centralized production facility, or compressor station. In response to the final Subpart OOOOb, U.S. EPA received petitions from stakeholders and affected facilities regarding specific provisions within the rule that present challenges to achieving and maintaining compliance within the final time frames. Petitioners raised concerns about supply chain constraints, limited emissions testing resources, and limited laboratory analytical capacity related to the ability to demonstrate compliance with control device testing and monitoring requirements. Petitioners also cited conflicting regulatory language and technical guidance from U.S. EPA that imposed compliance deadlines perceived to be too stringent by many affected facilities and stakeholders within the sector.

In response to the concerns that were raised in the petitions, U.S. EPA issued an interim final rule on July 31, 2025, in which multiple Subpart OOOOb compliance deadlines were extended to January 22, 2027, providing affected facilities with an additional 18 months to procure equipment, coordinate performance testing schedules, and implement monitoring systems into facility operations and project plans. The deadline extensions align with U.S. EPA’s plan to issue a final reconsideration of Subparts OOOOb and OOOOc in July 2026, where certain provisions will be reviewed and likely revised. By specifying deadlines that allow sufficient lead time for affected facilities to comply with applicable Subpart OOOOb provisions, U.S. EPA aims to ensure a structured transition period providing regulatory certainty across the sector during the reconsideration process. The following table outlines several important compliance requirements promulgated within Subpart OOOOb that have been granted deadline extensions within the issuance of the interim final rule.

¹ The provisions of the Super Emitter program under 40 CFR Part 60, Subparts OOOO and OOOOa were suspended until January 22, 2027.

Extensions to State Plan Requirements under Subpart OOOOc

On March 8, 2024, emissions guidelines for existing sources in the crude oil and natural gas source category were finalized under 40 CFR Part 60, Subpart OOOOc. The final rule includes a deadline of March 9, 2026 for state regulatory agencies to submit their respective state plans for the implementation of Subpart OOOOc. Since the rule was finalized, U.S. EPA has received many inquiries from state regulatory agencies regarding extension of the deadline and the subsequent consequences of late state plan submissions. These inquiries ultimately prompted U.S. EPA to reassess the submission deadline for state plans, allowing states more time to develop their plans in accordance with the final emissions guidelines. The July 31, 2025 interim final rule extended the state deadline to January 22, 2027. This deadline extension also grants U.S. EPA sufficient time to conduct their reconsideration of Subpart OOOOc prior to a submittal deadline.

What’s Next?

The interim final rule became effective immediately (without formal notice and comment) upon publication, citing the ‘good cause’ exemption under the Administrative Procedure Act. The interim final rule provides targeted extensions to facilitate realistic and achievable compliance with GHG and VOC control requirements under Subparts OOOOb and OOOOc. On August 15, 2025, U.S. EPA extended the deadline for the public to submit comments on the interim final rule through October 3, 2025. Until then, U.S. EPA is accepting public comments on all aspects of the interim final rule under Docket ID. No. EPA-HQ-OAR-2025-0162. While the extended compliance deadlines offer relief, facilities can take advantage of the extensions to develop compliance strategies and plans, including procurement of long-lead equipment and services, to comply with the rule. The interim final rule was issued in the shadow of U.S EPA’s March 12, 2025 announcement of their planned reconsideration of specific provisions under Subparts OOOOb and OOOOc. U.S EPA is also considering certain provisions under Subparts OOOOb and OOOOc related to NHV monitoring at flares and enclosed combustion devices and flaring of associated gas. Until a reconsideration rule is proposed, affected facilities should remain engaged in the rulemaking process and maintain communication with their respective legal, technical, and environmental professionals.

Need help understanding how this affects you?

ALL4’s oil and natural gas experts are well-versed in all aspects of evaluating applicability to the federal regulations, developing plans for compliance, and implementing practical strategies aligned with U.S. EPA’s evolving regulatory landscape. If you are wondering how U.S. EPA’s final rule will affect your facility or ongoing projects directly, please reach out to your ALL4 project manager or contact Daniel Hickey at dhickey@all4inc.com.

Who is SCAQMD and Why Industrial Facilities Should Care

Every industrial facility in the Greater Los Angeles Area is touched by South Coast Air Quality Management District (SCAQMD or District) rules, and with dozens of regulations and permitting requirements, it can be difficult to see the full picture of what the District actually does. SCAQMD has jurisdiction over stationary sources of air pollutants in Orange County and the urban areas of Los Angeles, Riverside, and San Bernadino Counties, commonly referred to as the South Coast Air Basin. The South Coast Air Basin is home to more than 17¹ million people, representing more than 40% of California’s populations and more total residents than every U.S. State² except for Texas, Florida, and New York. Facilities located in SCAQMD’s jurisdiction are subject to some of the most stringent air quality regulations in the United States.

This article is the first in a series designed to demystify SCAQMD rules, policies, and programs. Our goal is to explain what the District does, why it matters for industrial facilities, and how companies can navigate their requirements without unnecessary surprises or delays.

Authority and Origins

In the late 1940s, the California State Legislature passed legislation that allowed counties to create unified air pollution control districts. Los Angeles County established the nation’s first air quality district and required major industry to obtain permits for emissions of air pollutants. Orange, Riverside, and San Bernadino Counties established their own districts in the 1950s, and by the late 1970s, the four county agencies were consolidated to form SCAQMD by the Lewis Presley Air Quality Management Act (Lewis Presley Act). The Lewis Presley Act granted SCAQMD the authority to:

• Regulate stationary sources of air pollution in the South Coast Air Basin.
• Adopt and enforce rules stricter than federal standards if needed.
• Prepare air quality management plans to demonstrate compliance with both state and federal clean air requirements.
• Issue permits and enforce conditions on industrial facilities.

While the Lewis Presley Act grants SCAQMD its local authority, the work of the District is driven by state and federal legislation. The federal Clean Air Act requires the U.S. Environmental Protection Agency (U.S. EPA) to set National Ambient Air Quality Standards (NAAQS) that every region must meet. The California Clean Air Act requires that each air district adopt the most stringent feasible controls to achieve the California Ambient Air Quality Standards (CAAQS). The California Air Resources Board (CARB) supports this process by compiling and submitting the State Implementation Plan (SIP), setting mobile source standards, and reviewing district plans. This framework requires SCAQMD to adopt strict rules for stationary sources so that the South Coast Air Basin can make progress toward meeting state and federal air quality goals.

Agency Structure and Governance

To understand how SCAQMD makes and enforces its rules, it helps to first look at how the District is structured and governed.

Governing Board

SCAQMD is directed by a 13-member Governing Board who meet monthly to establish policies, and approve, reject, or amend rules. The Governing Board is comprised of 10 elected officials from communities located in the South Coast Air Basin and three political appointees.

Hearing Board

The SCAQMD Hearing Board is a quasi-judicial body authorized under the California Health and Safety Code to provide relief from SCAQMD regulations under certain circumstances.

District Operations

SCAQMD is organized into functional teams responsible for day-to-day operations of the District.

Executive Office

The Executive Office is appointed by the Governing Board and is responsible for management and the development and implementation of strategies to attain the NAAQS.

Legal

The Legal Department advises the Governing Board and District Staff on all aspects of operations, enforcement, and litigation. The Legal Department represents the District in proceeding before the Hearing Board.

Monitoring and Analysis

The Monitoring and Analysis Division (MAD) is responsible for maintaining SCAQMD’s air quality monitoring network and managing the District’s source testing program.

Technology Advancement

The Technology Advancement Office (TAO) partners with private industry and local, state, and federal agencies to co-sponsor projects that develop and demonstrate low- and zero-emissions technologies. TAO also manages incentive programs that help local fleets adopt cleaner equipment.

Engineering and Permitting

The Engineering and Permitting (E&P) group is responsible for administering SCAQMD’s permitting program, including the REgional CLean Air Incentives Market (RECLAIM) permits, Permits to Construct and Permits to Operate equipment for non-RECLAIM facilities, and the Federal Title V Operating Permit Program.

Compliance and Enforcement

The Compliance & Enforcement (C&E) group is responsible for verifying compliance with permit conditions and air quality regulations through inspections and record reviews. The C&E group has the authority to issue Notices to Comply (NTC) and Notices of Violation (NOV) which are then adjudicated by the Legal Department. The C&E group is also responsible for responding to public complaints.

Planning, Rule Development, and Implementation

The Office of Planning, Rule Development, and Implementation manages SCAQMD’s air quality planning and develops new rules or amendments to existing ones. Key programs include emissions reporting, air quality modeling, health risk assessments, California Environmental Quality Act (CEQA) review, socioeconomic analysis, and air quality management plans.

Legislative, Public Affairs and Media

The Office of Legislative, Public Affairs and  Media handles community outreach, small business assistance, government relations, and media communications. Its mission is to promote public participation and understanding of SCQMD’s rules, plans, and policies.

Finance

The Finance Office administers all financial functions of the District, including managing permit fees, annual emissions fees, and other payments required from regulated facilities.

Information Management

The Information Management Office handles SCAQMD’s technology systems, including public records requests, records management, and online tools such as the FIND system that provide access to permits, compliance, and emissions data.

So What Does All This Mean?

You may be thinking, this all sounds important, but why should I care?

Compliance is not optional

SCAQMD issues hundreds of permits each year and conducts countless inspections. The District has the legal authority to penalize any industrial facility for violations of their rules. Noncompliance can trigger civil penalties of up to $75,000 per day³. In certain cases, SCAQMD may also refer violations to the local District Attorney for criminal prosecution.

Compliance and permitting records are public

Permits and compliance records are available to your neighborhood, your business partners, and the general public through online databases and public records requests. Staying ahead of compliance issues not only limits operational and financial risk but also protects your reputation and brand.

Looking at the long term

SCAQMD consistently reviews and updates its rules to meet state and federal air quality standards. Identifying these changes early and participating in the rule development and comment process can help companies avoid being caught off guard, incorporate compliance into capital planning, and position sites to take advantage of incentive programs where available.

Closing Thoughts

The South Coast Air Basin faces some of the United States’ most significant air quality challenges. SCAQMD has been tasked with meeting those challenges through one of the most complex regulatory and administrative frameworks in the country. Navigating this regulatory regime not only requires an understanding of the District’s rules, but its planning, enforcement, and incentive frameworks. For industrial facilities in the South Coast Air Basin, compliance is not just about meeting today’s requirements, it is about anticipating tomorrow’s changes, protecting your reputation, and positioning for long-term success.

Stay tuned for future 4 the Record articles where we will dive deeper into specific SCAQMD rules and programs. If you are interested in learning how to navigate SCAQMD’s rules and structure, please reach out to Michael McHale at 610.422.1131 or mmchale@all4inc.com.

¹ https://www.aqmd.gov/nav/about

² Population data as of the 2020 U.S. Federal Census (https://www.census.gov/data/tables/time-series/demo/popest/2020s-state-total.html)

³Penalty ranges established by the California Health & Safety Code §42402.3. Penalties range from $5,000 per day for general violations up to $75,000 per day for knowing and willful violations, adjusted annually for inflation. Willful and intentional release of air pollutants that causes injury to any person can result in greater penalties.

U.S. EPA Proposes Revised Standards for Open Burning/Open Detonation of Waste Explosives

On March 20, 2024, the U.S. Environmental Protection Agency (EPA) proposed amendments to the standards governing the open burning and open detonation (OB/OD) of waste explosives. While OB/OD of hazardous waste was initially prohibited in 1980, an exception was made for waste that “cannot safely be disposed of through other modes of treatment” (40 CFR §265.382). However, in 2019, reports discussing new, safer disposal technologies prompted the U.S. EPA to issue updated standards in a June 2022 memorandum. They have now proposed further clarifications and revisions.

Key Revisions

The proposed changes clarify and expand upon several aspects of the Resource Conservation and Recovery Act (RCRA) requirements for OB/OD operations. The U.S. EPA’s goal of these proposed amendments is to improve implementation of requirements for how facilities must evaluate and use alternative technologies determined to be safe and available for treating waste explosives in lieu of OB/OD:

• Alternative Technology Evaluations: Revised criteria, timing, and required documentation
• Applicability: Including a de minimis exemption and provisions for emergency response scenarios
• Technical Standards: Updated monitoring and operational standards for OB/OD units
• Prohibited Wastes: Specific waste types are no longer eligible for OB/OD treatment
• Mobile Treatment Units (MTUs): New permitting framework

What Does This Mean?

The U. S. EPA continues to emphasize that OB/OD should be a last resort. Where safe and available alternatives exist, they must be prioritized. However, the agency acknowledges that OB/OD may still be necessary in certain situations and has proposed targeted exceptions.

Alternative Technology Evaluations
Expanding upon the 2022 memo, the proposed U.S. EPA amendments clarify guidelines regarding timing, definitions of “safe” and “available,” and specific content requirements. Facilities must demonstrate why alternative technologies are not viable in order to qualify for OB/OD permitting. If an alternative technology evaluation finds that alternative technology is available, the facility may be required to phase out their OB/OD activities through off-site waste disposal or installation of alternative technology. In addition, a facility-specific compliance schedule may be included in their permit by the responsible regulatory agency. Installation of new disposal devices require RCRA permit modifications. New minimum technical standards for OB/OD operations will also be incorporated into existing permits.

De Minimis Exemption
Facilities generating 15,000 pounds or less of net explosive weight (NEW) annually may qualify for a de minimis exemption, provided they can meet demonstration and documentation requirements. This exemption allows continued OB/OD operations at lower-volume facilities.

Emergency Treatment Provisions
For emergency scenarios requiring expedient responses to immediate threats exempt from permitting, OB/OD is allowed, but post-incident reporting is required. For emergencies under a permit, facilities must first assess whether safe alternative treatments are available within a reasonable timeframe. This assessment must be documented and submitted to the proper regulatory agency within five days of beginning treatment.

Prohibited Wastes
The U.S. EPA proposes to prohibit OB/OD treatment of certain waste types that pose unacceptable risks or are not effectively treated by OB/OD. These wastes include:

• Mixed wastes containing more than trace amounts of depleted uranium (DU)
• White and red phosphorus
• PAX-21 (Picatinny Arsenal Explosive 21)
• Polychlorinated biphenyls (PCBs)
• Improved Conventional Munitions (ICMs)/cluster munitions
• Chemical weapons as defined by the U.S. EPA

These prohibitions do not apply during emergencies that are exempt from RCRA permitting.

Mobile Treatment Units
A new permitting framework for MTUs has been proposed. MTUs may provide faster, more cost-effective treatment for small waste volumes and reduce the need to transport hazardous materials off-site.

What You Can Do

Facilities that employ OB/OD can prepare for the implementation of these proposed changes by starting alternative technology analyses and strategizing ways to comply with the proposed amendments.

How ALL4 Can Help?

As organizations prepare for these regulatory changes, ALL4 is here to help navigate the revised OB/OD permitting requirements, assess eligibility for exemptions, evaluate alternative waste treatment options, and guide you through any required regulatory processes. Our goal is to support your compliance efforts while prioritizing environmental and occupational safety. To learn more, contact the ALL4 team through Meredith Pedraza at mpedraza@all4inc.com.

Updates on the California Air Resources Board SB 253/261 Climate-Related Legislation

On Thursday, August 21, 2025, the California Air Resources Board (CARB) hosted a public workshop on Senate Bills (SB) 253 and 261, also known by CARB as the 200’s. The workshop provided important clarification on California’s corporate climate disclosure laws, also known as the Climate Accountability Package. For more information about the laws’ applicability, timeline, and enforcement, refer to ALL4’s previous blog on this topic. CARB is currently developing implementation regulations for these laws and is seeking public feedback. The update below summarizes CARB’s announcements and outlines the next steps to help companies doing business in California prepare for compliance.

Key Takeaways from the August 21^st Workshop:

• Applicability of the Climate Accountability Package
  • SB 253 applies to entities (public or private) with $1 billion+ in annual revenue doing business in California.
  • SB 261 applies to entities with $500 million+ in annual revenue doing business in California.
  • “Doing business in California,” and “revenue,” remain under review, with CARB continuing to request stakeholder input.
• SB 253 – The Climate Corporate Data Accountability Act
  • CARB has proposed a submittal deadline of June 30, 2026 for reporting Scope 1 and Scope 2 greenhouse gas (GHG) emissions from Fiscal Year 2025 data, with limited assurance.
  • The draft report format template is to be released for public comment in September 2025.
  • The annual CARB fee for SB 253 is proposed to be set at $3,106 per year, per reporting entity.
  • Scope 3 GHG emissions reporting timelines will be established by CARB through a future rulemaking.
  • Scope 1, Scope 2, and Scope 3 GHG emissions reporting may be consolidated at the parent company level.
• SB 261 – Climate-Related Financial Risk Disclosure
  • The reporting deadline for the climate-related risk assessment disclosure remains January 1, 2026, for subject entities.
  • SB 261 does not specify Calendar Year or Fiscal Year data. CARB states that covered entities should use the most recent or best available data for their first report.
  • Reporting entities must publish disclosures on their websites and submit them to CARB’s public docket, which will open on December 1, 2025. On that date, CARB will begin posting a docket where entities must provide the location of their public link to their initial climate-related financial risk report under this program. The docket will remain open until July 1, 2026, serving as a centralized, transparent resource for the public to access all climate-related financial risk reports.
  • The annual CARB fee for SB 261 is proposed to be set at $1,403 per year, per reporting entity.
  • Scenario analysis will not be required in Year 1 reporting; qualitative analysis will be sufficient in later years, though quantitative analysis is encouraged.
  • GHG emissions reporting will not be required in Year 1.
• Fee Structure and Applicability
  • The CARB fees for SB 253 and SB 261 are cumulative for entities subject to both laws.
  • The CARB fees are to be paid annually per reporting entity (even though SB 261 reporting is biennial).
  • The CARB fees will be adjusted for inflation as necessary.
• Assurance Standards
  • CARB is working to finalize the assurance requirements in the rulemaking process.
  • The assurance standards under consideration include International Standard on Sustainability Assurance (ISSA) 5000, AccountAbility AA1000, the International Organization for Standardization (ISO) 14060 family of standards, and Association of International Certified Professional Accountants (AICPA).
  • Stakeholder feedback on assurance standards is actively being solicited by CARB.

Enforcement and Compliance

• CARB will exercise enforcement discretion in 2026, recognizing the challenges of early implementation. Entities that demonstrate good-faith efforts to comply will not face penalties for incomplete reporting.
• In subsequent years, CARB will provide additional enforcement guidance as regulations mature.

Next Steps for Businesses

1. If you need a refresher on CARB’s Climate Accountability Package, go back and review ALL4’s blog from earlier this year for clarification and guidance.
2. Companies should determine whether either of California’s climate laws apply to them.
3. Companies subject to SB 253 should begin collecting Scope 1 and Scope 2 GHG emissions data for Fiscal Year 2025 now to meet the June 30, 2026 reporting deadline.
4. Companies subject to SB 261 should prepare their first climate-related financial risk report by January 1, 2026 focusing on the most recent or best available data for their first report.
5. Entities should anticipate annual CARB fees ($3,106 per year for SB 253; $1,403 per year for SB 261), with adjustments for inflation.
6. Companies are encouraged to provide feedback on definitions, assurance standards, and draft report formats utilizing CARB’s public comment solicitation board.

How ALL4 Can Help

ALL4 is closely monitoring CARB’s implementation of SB 253 and SB 261, as well as developments in GHG emissions disclosure, climate-risk reporting, and enforcement guidance, to help businesses prepare for California’s climate-accountability requirements. Our team of sustainability experts can support your company by developing GHG emissions inventories and conducting climate-related risk assessments to ensure accurate and compliant disclosure.

For questions about these legislations, please contact James Giannantonio, Managing Consultant (jgiannantonio@all4inc.com) or Daryl Whitt, Technical Director (dwhitt@all4inc.com).