Learn about SCS Engineers Air Emissions Services
The other night, I woke up in a bit of a panic and thought that I must have missed an announcement by the USEPA regarding the PM2.5 NAAQS reconsideration! Did I?
The answer, thankfully, is no! However, that is not any reason to relax and take no action.
By way of background, the Clean Air Act requires that the USEPA set National Ambient Air Quality Standards (NAAQS) for each of the criteria air pollutants, including particulate matter (PM). These NAAQS are based on the best available science and aim to protect human health and welfare. In June of 2021, the USEPA announced that they would reconsider the 2020 PM NAAQS final action under the prior administration that did not lower any standards. Then, in January 2023, the USEPA published the proposed rule to revise the PM2.5 primary annual standard down from 12 micrograms per cubic meter (µg/m3) to within a range of 9-10 µg/m3. In that proposal, the agency retained the 24-hour standard of 35 µg/m3.
The comment period for this proposed rule has since closed, and the agency is now working through over 5,000 submitted comments. It is unclear when the USEPA will issue the final rule (it could be any day now) and if the new annual standard will be set at 9 or 10 or something in between.
What does this mean for me as a regulated source? What should you do? SCS Engineers recommends the following actions:
Additional Resources:
About the Author: Rafe Christopherson, PE, is a project director and SCS’s industrial Clean Air Act leader. He is an air quality professional with a wide variety of experience over his 25-year career. His expertise includes consulting, working at an air quality regulatory agency and with industry. His expertise includes semiconductors, biofuels, pulp and paper, hardwoods, power generation, refineries, and general manufacturing. If you are interested in more information on this PM2.5 NAAQS reconsideration process and what it might mean for your business, you may reach Rafe at or via LinkedIn.
The proposed AERR rule would require nearly 130,000 facilities to report air toxics emissions directly to EPA. It would also give states the option to collect the air toxics data from industry (rather than states) and report it to EPA, provided the Agency approves their program. This proposed action would allow for EPA to annually collect (starting in 2027) hazardous air pollutant (HAP) emissions data for point sources in addition to continuing the criteria air pollutant and precursor (CAP) collection in place under the existing AERR.
Here are some key things to know about the proposed rule from the EPA website:
1. It would require air toxics (hazardous air pollutant) emissions reporting. While most states voluntarily report air toxics emissions data to EPA now, reporting is not consistent nationwide. The proposal would require many industrial facilities to report air toxics emissions data and offers states the option to report emissions on behalf of the industry sources in their states.
2. It would mean that more facilities must report emissions every year by using the same emissions thresholds every year to determine whether a facility’s detailed emissions information must be reported.
3. It would fill reporting gaps for some portions of Indian country and federal waters. The AERR proposal would require industry to report emissions for certain facilities that operate in those areas and that currently are not reported.
4. It includes provisions to limit the burden on small businesses. The proposal includes flexibilities such as allowing certain small businesses to report a facility’s total air toxics emissions instead of detailed data and exempting many collision repair shops from air toxics reporting requirements.
5. It would provide EPA information that would help the Agency improve its estimates of emissions from prescribed fires. EPA is committed to helping communities and our federal, state, local, and tribal partners manage the health impacts of smoke from wildland fires, including prescribed fires. Prescribed fire is a land management tool that can reduce the likelihood of catastrophic wildfires by reducing the buildup of unwanted fuels.
Additional Resources:
On June 12, 2023, the Maryland Department of the Environment (MDE) published its final regulation addressing the control of landfill gas (LFG) methane emissions from municipal solid waste (MSW) landfills in the state (promulgated under COMAR 26.11.42). Methane is a potent greenhouse gas (GHG) with a global warming potential more than 25 times greater than carbon dioxide. The rule has been several years in the making and is modeled after similar rules in California and Oregon. The rule also incorporates provisions from the EPA’s federal landfill air regulations under NSPS & EG 40 CFR 60 Subparts Cf and XXX and NESHAP CFR 63 Subpart AAAA and stands among the most stringent in the US.
The new regulation will be submitted to the EPA for approval as part of Maryland’s state plan for MSW landfills (state plan). The state plan will be equivalent to or more stringent than the EPA’s NSPS & EG 40 CFR 60 Subparts Cf and XXX and NESHAP CFR 63 Subpart AAAA and will apply to smaller and mid-sized landfills not currently subject to the EPA’s federal rules. MDE estimates that 32 active and closed MSW landfills in the state will be subject to the rule. The rule is effective June 12, 2023.
Some key provisions of the rule include:
This rulemaking has been several years in development and is consistent with Maryland’s GHG Reduction Act of 2009 and the recent Climate Solutions Now Act of 2022 that requires Maryland to become “net zero” for GHG emissions by 2045, with an interim goal of achieving 60% GHG reductions by 2031 (over 2006 levels). MDE estimates this rule will achieve a 25-50% reduction in GHG emissions from affected landfills.
Additional information on MSW regulations and GHG emission reductions:
Dr. Ketan Shah’s paper entitled “Single-use plastic bottle emissions using life cycle assessment for the US States, challenges, impact, and recommendations” is publishing in June, but those attending the Air and Waste Management Association conference in Orlando, Florida, have the chance to hear Dr. Shah discuss his methods used to develop methane emission estimates and recommendations to reduce them.
Plastics in solid waste management (SWM) are an exigent and pressing problem for many cities. Globally landfills/open dumpsites are used to dispose of over 80% solid wastes, currently serving around 3.5-4 billion people. This number is expected to grow with increased urbanization and population growth (ISWA, 2015).
Methane generation, recovery, and emissions projections for single-use plastic bottles play a vital role in the recycling industry. The scope of work described in this research project includes providing the basis for the methane estimates that discuss the data, assumptions, and calculation methods used to develop the estimates.
Methane emissions estimates to help assess the potential of single-use plastic bottles will have on greenhouse gas (GHG) emissions. As some U.S. states move towards requiring extended producer responsibility (EPR) for the packaging industry to address its waste management impacts, the analysis for the project commends firms for taking steps to pro-actively find a waste management solution for single-use plastic bottles, which may be the next target for EPR legislation.
Objective 1 – Develop Estimates of emissions from single-use plastic bottles using OpenLCA software based on Life Cycle assessment analysis.
Objective 2 – Prepare Comparative analysis for alternative recyclability scenarios.
Objective 3 – Recommendations and solutions to the single use plastic bottles challenge.
The case study results are based on the assumptions for the emissions from the single-use plastic bottles supply chain from cradle to grave. Finally, recommendations for these impacts and challenges will be discussed in detail. Diverting single-use plastic bottles going to landfills helps in reducing the overall environmental impact.
A&WMA ACE 2023 (awma.org). The Air & Waste Management Association (A&WMA) brings leading environmental scientists, practitioners, regulators, and leading environmental firms such as SCS Engineers together to share the latest initiatives addressing environmental issues facing communities such as climate change, exposure reduction through innovative technology and regulatory approaches, sustainability, community monitoring, and environmental justice.
Additional Resources:
Odor attribution is a complicated process when nuisance odors are intermittent and come from more than one source. Today’s blog discusses technological advances in olfactometers and processes to investigate and resolve industrial or agricultural odors.
To investigate odors, SCS begins by reviewing odor complaints for patterns based on location, time of day, the month of the year, and local wind conditions. We then use a site survey to identify candidate sources of odor that may contribute to the region’s odor complaints. Next, we assess the relative contributions of the most probable sources identified by collecting odor samples at/near each source and upwind, downwind, and crosswind. Traditionally, a limited number of odor samples could be collected daily in Tedlar® bags and shipped overnight to a certified laboratory for analysis by an odor panel. The odor panel uses an olfactometer to sniff air samples at varying dilutions for odor concentration, character, and intensity following American Society for Testing and Materials (ASTM) methods.
In certain situations, however, using a portable olfactometer in the field is more efficient. SCS recently implemented the Scentroid SS400 Six Station Portable Olfactometer Odor Lab for large odor studies. The Scentroid SS400 is the world’s only portable six (6) panel olfactometer compliant with European Standard EN 13725/2003 and ASTM E679-04 and is compact for easy transportation and deployment in remote locations. The Scentroid SS400 allows us to:
By having more data, our SCS professionals gain insight into complex nuisance odors and propose targeted mitigation measures that reduce odor concentrations downwind. With over 30 years of experience resolving odors from landfills, wastewater treatment plants, composting facilities, agricultural and manufacturing facilities, we’re confident we can help your facility come up smelling like roses too.
Meet the Author: Greg Hauser is an SCS Project Director responsible for environmental compliance projects. He has over 30 years of experience with compliance topics such as air quality permitting, emission inventories, dispersion modeling, health risk assessments, and odor impact assessments. Mr. Hauser is experienced conducting odor studies of composting, landfill, and wastewater treatment plant operations. He has surveyed facilities to identify sources of interest, collected field samples of odorous emissions, developed odor emission profiles based on odor concentrations and odor flow rates, and conducted dispersion modeling to predict odor concentrations at or beyond the facility’s property boundary. He also provides health risk assessments for aerospace, manufacturing, wastewater treatment, and oil and gas facilities.
Additional Resources:
Air permitting compliance is a crucial aspect of operating a facility that generates air emissions. The process involves obtaining permits from regulatory agencies that establish requirements to demonstrate that the facility operates within limits set by air quality regulations.
Air permitting is not just for industrial operations but impacts many businesses.
In Miami-Dade County, Florida, the agency responsible for issuing air permits is the Department of Environmental Resources Management (DERM). Businesses that emit air pollutants, such as fine particulate matter (dust), volatile organic compounds, and hazardous air pollutants, or which operate combustion equipment such as ovens, furnaces, boilers, and backup power generators must obtain air permits to operate legally. The Florida Department of Environmental Quality provides state guidance here. These permits are required to ensure that the facility’s emissions are within limits set by air quality regulations and that the facility is taking the necessary steps to control and reduce emissions.
Local business example
In the case of one apparel printing facility in Miami-Dade County, SCS Engineers (SCS) was hired to assist with obtaining the necessary air permits from DERM. The scope of services included reviewing current and proposed operations information, calculating air emission estimates, and preparing the narrative and application forms. SCS also prepared a Request for Information (RFI) to confirm the necessary background information, such as equipment specifications, facility layout, projected usage, and operating records. The deliverables included an Air Construction Permit Application and an Air Operating Permit Application. In this case, SCS could prove that the client did not need a permit even though the regulatory agency thought they might.
What are the steps?
The process of obtaining an air permit can be complex and time-consuming, which is why businesses often hire specialized environmental engineering firms to assist them. In this example, SCS provided DERM with a detailed report and application package, including a process flow diagram, equipment specifications, and actual and potential emissions calculations.
It’s important for businesses operating in Miami-Dade, or any county, to understand the air permitting process and the regulations set by local authorities. Environmental engineering firms can provide more accurate and detailed information, so management understands the specific air quality regulations that apply to their business.
The value is in implementing the practices necessary to maintain compliance with air quality regulations and keeps your reputation with workers and the community stellar. Businesses continuing to operate illegally face administrative and civil violations, court actions, and potential environmental insurance challenges. Another consideration is that the same engineering firm can likely advise you on stormwater and groundwater permits and compliance for your facility.
About the Author: Troy Schick, PE, is a Project Manager based in our Miami, Florida, office. He is a Professional Engineer licensed in Florida and a Qualified Stormwater Management Inspector.
Stormwater and Air Permitting Compliance Resources for Businesses:
MDE Regulatory Alert: Maryland Landfill Air Regulation
On December 30, 2022, the Maryland Department of the Environment (MDE) published a proposed regulation addressing the control of landfill gas (LFG) methane emissions from municipal solid waste (MSW) landfills in the state. Methane is a potent greenhouse gas (GHG) with a global warming potential of more than 25 times greater than carbon dioxide. The proposed regulation is modeled after similar rules in California and Oregon, incorporates provisions from the EPA’s federal landfill air regulations under NSPS & EG 40 CFR 60 Subparts Cf and XXX and NESHAP CFR 63 Subpart AAAA, and would become among the most stringent in the US.
The new regulation will be submitted to the EPA for approval as part of Maryland’s state plan for MSW landfills (state plan). The state plan will be equivalent to or more stringent than the EPA’s NSPS & EG 40 CFR 60 Subparts Cf and XXX and NESHAP CFR 63 Subpart AAAA, and will apply to smaller and mid-sized landfills not currently subject to the EPA’s federal rules.
MDE estimates that 32 active and closed MSW landfills in the state will be subject to the proposed regulation.
Some key provisions of the rule include:
This rulemaking has been several years in development and is consistent with Maryland’s GHG Reduction Act of 2009 and the recent Climate Solutions Now Act of 2022 that requires Maryland to become “net zero” for GHG emissions by 2045, with an interim goal of achieving 60% GHG reductions by 2031 (over 2006 levels). MDE estimates that once implemented, this rule will achieve a 25-50% reduction in GHG emissions from affected landfills. MDE estimates the capital costs associated with rule compliance would range from $1 to $3 million, annual operating and maintenance costs range from $150k to $400k, and additional costs for monitoring (~ $60k annually), recordkeeping, and reporting.
MDE has scheduled a virtual public hearing on the proposed action at 10:00 am on February 1, 2023. Comments can be submitted by 5:00 pm (Eastern Time) on February 1, 2023, to Mr. Randy Mosier of MDE at .
For additional information on MSW regulations and GHG emission reductions, please visit scsengineers.com or one of SCS’s nationwide offices.
Compounded by rising labor and regulatory costs, landfill operations challenges for owners and operators are liquids and greenhouse gases. Gas collection and control systems, leachate management strategies, and treatment technologies all help create efficiencies. But so does new technology.
In our two-part educational series, we use case studies to demonstrate combinations of integrated SCADA, IIoT, drones, satellites, and Geographical information systems (GIS) technologies. Using clear, straightforward language, our panelists explain which technology is best for what and when integrating these technologies better serves your landfill’s and composting operation’s challenges and budget.
Recorded in front of a live audience who send questions to our panelists specific to their operational needs we cover monitoring, liquids, and labor challenges – with an aim to introduce new technologies that solve some of your most expensive challenges. SCS’s forums are educational, non-commercial webinars with a Q&A forum throughout; they are free and open to all who want to learn more about landfill and composting technology. We recommend these discussions for landfill and organics management facility owners/operators, technicians, environmental engineers, municipalities, and environmental agency staff.
View Part I focused on drones, satellites, and GIS technologies which are valuable for landfill permitting, design, and monitoring liquids and gas well conditions.
View Part II focused on SCADA and remote monitoring & control systems – when and why using real-time data can create efficiencies and reduce risk at your landfill and are useful for compost operations, and anaerobic digestors.
If you would like to join our mailing list for these monthly forums, please contact us at – SCS never shares or sells your contact information.
The U.S. Environmental Protection Agency (EPA) has issued a proposed rulemaking (Federal Register, Vol. 87, No. 198, Friday, October 14, 2022) that would address a 2008 Fugitive Emissions Rule that was subsequently granted reconsideration based upon a petition from the National Resources Defense Council (NRDC). The key issue is how fugitive emissions are considered under Section 111 of the Clean Air Act (CAA), as related to the definition of modification.
Modification means any physical change in, or change in the method of operation of, a stationary source which increases the amount of any air pollutant emitted by such source or which results in the emission of any air pollutant not previously emitted. 42 U.S. Code § 7411(a)(4).
In 2008, the Bush EPA published its Fugitive Emissions Rule that sought to “reconsider” the inclusion of fugitive emissions under this language. Fugitive emissions are defined as:
Those emissions which could not reasonably pass through a stack, chimney, vent, or other functionally-equivalent opening.
NRDC’s petition for reconsideration argued that the Bush EPA weakened the standard for determining major modifications by excluding fugitive emissions from major Prevention of Significant Deterioration (PSD) and non-attainment New Source Review (NSR) applicability.
The proposed rulemaking would result in a formal reversion to the pre-2008 language. EPA’s Director for its Office of Air Quality Planning & Standards (OAQPS) has indicated that the rule “would require fugitives to be counted in all new and modified major source determinations,” effectively ending the Bush-era limitations on counting of fugitive emissions.
The potential impact of EPA’s planned fugitive emissions rule may prove significant and is expected to affect a wide range of diverse industry sectors being impacted, such as power generation, oil & gas extraction, mining, paper mills, petroleum refining, chemical manufacturing, coatings operations, and solid waste facilities. In particular, both landfills and compost facilities can have significant fugitive emissions.
Based on our current understanding, the proposed rule will effectively eliminate the ability to exempt fugitive emissions under the current exemption in 40 Code of Federal Regulations (CFR) 52.21(i)(vii). This would mean that if a source is an existing major PSD or non-attainment NSR source for ANY pollutant, and modifies, then both non-fugitive AND fugitive emissions for ALL pollutants must be counted to see if the project is a major modification under PSD/NSR. Triggering a major modification would also mean that fugitive emissions are included in the various compliance elements of PSD or NSR (e.g., best available control technology [BACT], lowest achievable emission rate [LAER], modeling, offsets. etc.).
To add more context for landfills, as an example, if an existing landfill, which is already deemed major due to carbon monoxide (CO) or sulfur dioxide (SOx) emissions from flares (Potential to Emit [PTE] >250 tons per year [tpy]), conducts an expansion that will result in 15 tpy of new particulate matter less than 10 microns(PM10) [and/or 10 tpy of PM2.5] fugitive emissions from windblown dust, this would be a major modification under PSD, requiring BACT and modeling for fugitive PM. This could also include BACT and other requirements for fugitive methane as a regulated greenhouse gas (GHG) or volatile organic compounds (VOCs)/non-methane organic compounds (NMOCs) from the additional fugitive landfill gas (LFG) emitted from the expanded landfill. Compost facilities can also have significant VOC emissions, which could put them at risk from this rule change.
Public comment on the rulemaking ends on February 14, 2023, which is an extension of the previous deadline. The solid waste industry will provide comments through the Solid Waste Association of North America (SWANA) and the National Waste and Recycling Association (NW&RA). This will be the last chance to have any effect on the rulemaking. Otherwise, landfills and possibly compost facilities could face more stringent requirements under the PSD and NSR programs when it comes to fugitive emissions.
Landfill and compost facility owners and operators may direct their questions pertaining to specific facilities to their Project Managers or .
Many landfills are still using hand-held monitoring of methane “hot spots” for compliance purposes while relying on models to estimate LFG emissions. Although technological developments in optical remote sensing and other methods offer significant improvements to measuring actual surface emissions from landfills, no single technology or method has risen to the top of the scientific hierarchy, gained universal acceptance, and achieved regulatory approval. Clearly, the technological advances provide more comprehensive methods for measuring methane concentration, identifying methane hot spots and leaks, and providing better coverage of the entire landfill surface. However, some technology falls short in their ability to provide accurate, consistent, and repeatable methane flux or emissions measurements.
As monitoring technology evolves, so have the various ways SCS takes measurements, from source level, drones, and high-altitude aircraft, to satellites. This paper presented at A&WMA by Patrick Sullivan and Raymond Huff summarises and provides details on the following methods:
• First order decay (FOD) modeling for landfills without active LFG collection systems.
• Non-FOD modeling for landfills without active LFG collection systems.
• FOD modeling with measured LFG collection.
• Non-FOD models with various site-specific data input.
• Measured LFG collection with estimated collection efficiency.
• Surface emission monitoring for compliance purposes.
• Ground-based or low-altitude imaging for concentration or hot spot measurement.
• Satellite and aerial imaging for concentration or hot spot measurement.
• Flux chamber testing.
• Ground-level plume measurement.
• Micrometeorology.
• Stationary path measurement.
• Reverse air dispersion modeling.
• Tracer studies.
• Low or high-altitude imaging.
• Hybrid methods.
