Introduction
In an era of increasing environmental awareness and regulatory scrutiny, industries are under growing pressure to reduce their environmental footprint and mitigate the impact of their operations on surrounding communities. One crucial aspect of this effort involves monitoring air emissions to ensure compliance with air quality standards and protect public health. This year, EPA has made notable developments in the National Emission Standards for Hazardous Air Pollutants (NESHAP) requirements, particularly with a focus on implementing fenceline monitoring. This article explores these updates and their implications for industries and the environment.
Understanding NESHAP Requirements
NESHAP, established under the
Clean Air Act (CAA), seeks to regulate, and limit the emissions of hazardous air pollutants (HAPs) from various industries. These standards are designed to safeguard public health and the environment by imposing emission limits and requiring the implementation of state-of-the-art control technologies also known as Maximum Achievable Control Technology (MACT) standards. Within eight years of setting MACT standards, EPA is directed by the CAA to review and revise the standards to account for improvements in air pollution control and/or prevention.
Introduction of Fenceline Monitoring into NESHAP
During the
2015 NESHAP update for Petroleum Refineries, EPA implemented amendments to 40 CFR Part 63, Subparts CC and UUU that required all petroleum refineries (also referred to as the Refinery Sector Rule) to implement fenceline monitoring programs to identify emissions from fugitive sources, such as equipment leaks, so that corrective action can be implemented quickly to reduce offsite impacts of air pollutants. This approach provides data that allows regulatory agencies, communities, and industries themselves to assess the potential impact of emissions on public health and the environment.
Although there were several successes and lessons learned in the Refinery Sector Rule fenceline monitoring program, EPA decided there was enough of a net benefit in lowering emissions that in 2023, EPA has proposed fenceline monitoring requirements for other industries with the intent of identifying offsite fugitive emission impacts and implementing corrective action. These industries include:
- Synthetic Organic Chemical Manufacturing Industry (SOCMI) (FR 25080, April 25, 2023). Also commonly referred to as the Hazardous Organic NESHAP (HON).
- Coke Ovens (FR 55858, August 16, 2023).
- Integrated Iron and Steel (FR 49402, July 31, 2023).
Proposed Fenceline Monitoring Methods
Not all industries exhibit identical emissions profiles for HAPs, making a singular monitoring approach insufficient to effectively target fugitive HAP emissions and create a substantial impact. Various air sampling methods have been carefully chosen to detect one or more prevalent pollutants or compounds released by specific industrial sources. These methods serve as surrogate for evaluating the comprehensive control strategies implemented within the facility. To illustrate, the monitoring requirements outlined in the Refinery Sector Rule rely on EPA Method 325A/B, utilizing benzene as a surrogate compound to ascertain the appropriate control strategy with an action level of 9 micrograms per cubic meter (µg/m3) as the net change in concentration (delta-c) between the highest and lowest concentration measured along the fenceline network. The newly established MACT standards, introduced in 2023, incorporate a variety of pre-existing and newly proposed monitoring techniques and delta-c action levels to fulfill the objective of identifying and regulating fugitive HAP emissions from industrial sources. The subsequent summary outlines each of these methodologies and elucidates their application within individual MACT standards.
EPA Method 325 A/B:
Method 325A and companion Method 325B are established methods which require placing passive sorbent tubes strategically along the facility’s perimeter to gather air samples that accurately reflect emissions from all sources. These tubes absorb VOCs over a 14-day sampling period. When each sampling period concludes, the passive samples are retrieved, securely sealed, and shipped to a laboratory for analysis. Here, through thermal desorption gas chromatography, the collected VOCs are meticulously analyzed and quantified to pinpoint the specific VOCs of interest. This sampling procedure is repeated after every 14-day sampling period accompanied by meteorological measurements used to evaluate the atmospheric conditions and movement of pollutants onto and off facility property. The frequency of sampling can be increased to aid in identifying and addressing short-term pollutant fluctuations and wind conditions, which might arise from potential cross-interference of emissions from neighboring sources.
As previously mentioned, Petroleum Refineries have implemented Method 325A/B for evaluating fugitive benzene impacts off site. Both the proposed HON and Coke Ovens MACT standards are proposing the implementation of fenceline monitoring using Method 325A/B. The Coke Oven MACT is proposing a similar approach to the Refinery Sector by focusing only on benzene while the HON is expanding the chemical compound list to include benzene, 1,3- butadiene, chloroprene, and ethylene dichloride, each with their own action levels.
For the HON MACT standard, EPA is proposing a combination of Method 325A/B and a new method (Method 327) for measuring fugitive emissions of ethylene oxide (EtO) and vinyl chloride from chemical manufacturing facilities. Method 327 is like EPA’s compendium of methods TO-15A and involves the utilization of specifically prepared canisters to collect samples, which are then subjected to analysis using a gas chromatograph (GC) in conjunction with either a low- or high-resolution mass spectrometer (MS) to ascertain the airborne concentration of specific volatile organic hazardous air pollutants (oHAPs) such as EtO and vinyl chloride. The distinctions between the proposed Method 327 and the existing TO-15A involve improvements in quality control protocols aimed at overcoming issues associated with measuring low concentrations and aim to lower the method detection limit (MDL). These enhancements encompass procedures for canister and sample train cleaning, field testing prerequisites, chromatogram scrutiny to identify interferences, and tighter sample holding times.
Proposed Method 327 is only being recommended for the chemical sector MACT standard. Samples are expected to be collected once every five days at eight strategically placed locations around the facility fenceline with action levels being based on three consecutive 24-hour sampling periods collected once every five days.
Yet to be Proposed Metals Monitoring Method:
The Integrated Iron and Steel MACT proposal introduced requirements for fenceline monitoring, aiming to identify offsite impacts resulting from emissions of fugitive sources from iron and steel facilities. However, the EPA did not specify a designated sampling method to fulfill these fenceline requirements. The implementation of these requirements has been postponed until an appropriate method is introduced and undergoes the necessary rulemaking processes.
In developing the proposed MACT standard, the EPA directed facilities to monitor for arsenic, chromium, and lead along the fencelines using the sampling method described in 40 CFR Part 50, Appendix B. Presently, there exist six EPA Compendium methods for quantitative analysis of inorganic compounds in particulate matter. Each method offers advantages and limitations for accurate assessments, contingent on factors such as the type of filter, sample collection methodology, and analytical technique for metal determination.
Due to the EPA’s postponement of the preferred approach for collecting and evaluating metal HAPs through a fenceline monitoring program, coupled with the assortment of available methods for determining metals in particulate samples, predicting the favored method becomes complicated. The EPA’s use of high-volume samplers and filters sets a precedent for necessitating power distribution to each sampling location. Conversely, alternative methods of particulate sample collection employ low-volume samplers that offer greater reliability and demand lower power for operation. Additionally, TSP is no longer a regulated pollutant and the available technologies for collecting TSP samples is limited while both PM10 and PM2.5 are criteria pollutants with a larger assortment of sample collection technologies. EPA needs to weigh the advantages and drawbacks for each method and the costs that will be implored on industry. Furthermore, once a method is selected, EPA will need to evaluate if the proposed action levels in the MACT standard are consistent between the final method and the method used in the development of the standard.
The Iron and Steel MACT is proposing to have samples being collected following the one-in-six day sampling schedule using the EPA Sampling schedule and action levels based on the 12-month rolling average of the concentrations. One exception that EPA is proposing that are not included in other MACT standards is a sunset provision to discontinue monitoring if the network shows concentrations below 50% of the action level for a 24-month period. EPA is soliciting comments on the sunsetting provision on whether a reduction in sample frequency would be appropriate.
Implications of Fenceline Monitoring
In addition to costs associated with implementation of a fenceline monitoring program and the operation and interpretation of the results, the fenceline monitoring requirements proposed in each of the MACT standards for Coke Ovens, Chemical Manufacturing Plants, and Iron and Steel industries will have some regulatory implications. The implementation of fenceline monitoring programs for the Refinery Sector Rule provides a roadmap for what to expect and lessons learned from establishing a fenceline monitoring program. First, implementation of a fenceline monitoring program allows for enhanced detection of previously unknown emissions from a facility. Understanding the data early enables operators to identify, manage, and mitigate equipment malfunctions or implement control strategies in a timely manner. Second, implementation of a fenceline monitoring program will have some initial challenges. Getting an early start on establishing a program enables a program shakedown period providing operators the necessary time to get logistical challenges ironed out before reporting is required. Facilities that are reporting data above an action level will need to perform a root cause analysis and start corrective action procedures to get the concentrations below the threshold. Facilities showing a chronic issue will need to establish a more comprehensive monitoring program which could result in continuous monitoring and source identification until the issue is resolved and monitoring shows the facility follows the rule.
Conclusion
Innovations in technology, environmental awareness, and regulatory scrutiny have driven the evolution of policy for industrial facilities to demonstrate the impact they have on adjacent communities. Forthcoming MACT standards for Coke Ovens, Chemical Manufacturing Industry, and Iron and Steel Industry include requirements for fenceline monitoring programs that are being used by EPA to identify, manage, and mitigate emissions from fugitive sources within these industrial facilities. Operators and proprietors of facilities in each of these sectors must allocate resources for both the establishment and upkeep of these monitoring networks, as well as the analysis and dissemination of data. Initiating fenceline monitoring programs ahead of schedule is recommended, offering an enhanced understanding of current emissions’ impacts, and speeding up corrective actions.
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Each Trinity fenceline monitoring project is custom-designed by our experts to ensure your monitoring technologies and networks meet your regulatory requirements. Upon request, Trinity can provide complete turnkey fenceline monitoring services including:
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