What is the benzene action level under MACT Subpart CC?

The benzene action level under MACT Subpart CC is 9 µg/m³ annual average concentration at the fenceline. When facilities exceed this level, they are required to conduct root cause analysis and implement corrective actions to identify and address emission sources.

What was the penalty in the 2025 EPA benzene enforcement case?

In the Spring 2025 enforcement case, the EPA imposed a civil penalty of $35 million against a facility with benzene fenceline concentrations exceeding 900 µg/m³. The facility was also required to install real-time monitoring systems and implement comprehensive emission control measures as part of the settlement agreement.

What are common benzene emission sources the EPA investigates?

The EPA commonly investigates storage tanks containing high benzene content materials (benzene, reformate, light naphtha, pyrolysis gasoline), marine vessel loading operations with vapor control failures, and wastewater treatment systems including uncontrolled DAF systems, junction boxes, and oil/water separators.

What monitoring technologies does EPA recommend for benzene compliance?

The EPA's enforcement alert emphasizes best practices including Optical Gas Imaging (OGI) with infrared cameras, benzene-specific photoionization detectors (PIDs) with parts-per-billion sensitivity, real-time monitoring systems like gas chromatographs, and GMAP mobile geospatial monitoring technology for rapid root cause investigations.

Will chemical manufacturing facilities face benzene fenceline monitoring requirements?

Yes, chemical manufacturing facilities subject to the HON (Hazardous Organic NESHAP) will face similar benzene fenceline monitoring programs in the near future, with the same root cause analysis and corrective action implementation expectations that currently apply to petroleum refineries under MACT Subpart CC.

What violations did the EPA allege in the 2025 enforcement case?

The EPA alleged violations related to untimely root cause analysis and ineffective corrective actions when benzene action levels were exceeded. Additional violations included BWON (Benzene Waste Operations NESHAP) violations, LDAR issues, storage tank problems, and flare operational violations.

How is EPA using fenceline monitoring data for enforcement?

The EPA is using elevated benzene fenceline readings as an entry point to trigger comprehensive facility-wide investigations. When action levels are exceeded, EPA inspectors examine related compliance programs including storage tanks, wastewater systems, LDAR programs, and evaluate the adequacy of root cause analysis and corrective action responses.

EPA Enforcement Alert: How Benzene Fenceline Results Are Opening the Door to Facility-Wide Investigations

Alliance Technical Group
Nov 4
3 min read

The EPA is using elevated fenceline readings as an entry point to take a deeper dive into other compliance programs, such as tanks, wastewater systems, and your facility's root cause analysis and corrective action response.

In September 2025, the EPA published an enforcement alert that signals a new era of scrutiny for benzene fenceline monitoring compliance under MACT Subpart CC. With the first enforcement case concluded in Spring 2025 and more actions expected, this appears to be an expansion of the agency's broader Benzene Waste Operations NESHAP (BWON) and storage tank enforcement initiatives. Fenceline monitoring has evolved from a compliance requirement into an investigative tool that can trigger comprehensive inspections of related air quality programs.

What's Driving EPA Enforcement to Use Benzene Fenceline Monitoring Results?

The EPA has identified recurring compliance issues during facility inspections:

Common Problem Areas:

Storage tanks containing high benzene content materials (benzene, reformate, light naphtha, pyrolysis gasoline)
Marine vessel loading operations with vapor control failures

Wastewater treatment systems including uncontrolled DAF systems, junction boxes, and oil/water separators

Beyond identifying emission sources, many facilities are failing to conduct adequate root cause analyses and implement timely corrective actions when benzene action levels are exceeded—violations that can trigger significant enforcement actions.

The Stakes Are High

The Spring 2025 enforcement case demonstrates what's at risk. The EPA took action against a facility with fenceline concentrations exceeding 900 µg/m³ and annual averages reaching 290 µg/m³—more than 30 times the 9 µg/m³ action level.

EPA alleged violations related to untimely root cause analysis and ineffective corrective actions, along with violations related to BWON, LDAR, storage tanks, and flares.

The facility was required to install real-time monitoring systems and implement comprehensive emission control measures as part of the settlement agreement, in addition to a civil penalty of $35 million.

Advanced Monitoring Solutions for Fenceline Programs

While this alert focuses on petroleum refineries under MACT Subpart CC, chemical manufacturing facilities subject to the HON will face similar fenceline monitoring programs in the near future—and the same root cause analysis and corrective action implementation expectations will apply.

The EPA's alert emphasizes using "best practices for finding root causes" of action level exceedances. These best practices require advanced monitoring technologies, all of which Alliance Technical Group offers:

Optical Gas Imaging (OGI) – Infrared cameras provide rapid screening across large refinery areas to identify fugitive emissions and leaks
Benzene-Specific PIDs – Handheld photoionization detectors with parts-per-billion sensitivity pinpoint benzene emissions at specific equipment interfaces
Real-Time Monitoring Systems – Gas chromatographs and continuous monitors provide near real-time measurements that correlate with wind direction and operational conditions
GMAP Technology – Mobile geospatial monitoring solutions deliver real-time, actionable data to identify unknown emission sources and conduct rapid root cause investigations

Each of these technologies addresses specific gaps the EPA has identified in current compliance programs, providing facilities with the tools needed to meet regulatory expectations and demonstrate environmental stewardship.

Partner with Alliance for Proactive Compliance

The regulatory and enforcement environment surrounding benzene is intensifying, and the path forward requires more than just awareness—it demands action and expertise.

For over 25 years, Alliance Technical Group has been helping refineries and chemical manufacturing facilities navigate complex air quality compliance challenges with proven monitoring technologies and experienced technical support. From site specific monitoring plans to initiating root cause analysis or providing expertise in corrective actions plans, Alliance provides a better way to handle compliance.

Don't wait for an enforcement action to strengthen your compliance program. Let Alliance be your partner in protecting your facility and staying up to date with regulatory best practices.

Contact Alliance Technical Group today to discuss how we can help your facility meet EPA's fenceline monitoring requirements and build a robust, defensible compliance program.

Contact Alliance Today ➜