U.S. EPA Finalizes Benzene Fenceline Monitoring for Coke Oven Facilities

In August of 2023, ALL4 covered the proposed monitoring amendments to the National Emissions Standards for Hazardous Air Pollutants (NESHAP) for Coke Ovens: Pushing, Quenching, and Battery Stacks (PQBS) and Coke Oven Batteries (COB) at 40 CFR Part 63, Subparts CCCCC and L. The United States Environmental Protection Agency (U.S. EPA) published the final amendments to the NESHAP for Coke Ovens in the Federal Register on July 5, 2024. The revisions are a result of the Clean Air Act (CAA) mandated risk and technology review (RTR) for PQBS and technology review for COB and address previously unregulated hazardous air pollutants (HAPs) and HAP emissions sources. As part of the revisions, U.S. EPA is requiring certain Coke Oven Facilities to measure fugitive benzene emissions at their fenceline (where fenceline is equivalent to the perimeter) using passive samplers.

According to U.S. EPA, benzene is ever-present at coke oven facilities, accounts for about 70 percent of emissions of all volatile compounds and is a surrogate for organic HAPs from fugitive sources at these facilities. U.S. EPA is requiring a minimum number of passive samplers collecting two-week time-integrated samples continuously, following EPA Method 325. These samples would be analyzed for benzene, background corrected for each sampling event, assessed against an annual action level, with results reported to U.S. EPA on a quarterly basis and made available to the public.

PASSIVE SAMPLING

Passive sampling involves using small inert-coated metal tubes filled with an adsorbent and special cap that allows ambient air to diffuse onto the sorbent at a fixed rate, thereby retaining the compound of interest. Following a two-week sampling period, the tubes are collected and sent to a laboratory for analysis, with new tubes installed to maintain continuous sampling.

The number of required samplers is based on the size of the COB plant per EPA Method 325, with a minimum of 12 equally spaced samplers. The final rule requires deployment of the first sampling period no later than July 7, 2025 for existing facilities and no later than July 7, 2025 or upon start up (whichever is later) for new facilities. In the final rule, U.S. EPA is requiring only coke oven facilities with production processes that have by-product chemical recovery (ByP) to conduct fenceline monitoring. U.S. EPA removed the monitoring requirement at coke oven facilities with heat and nonrecovery (HNR) because these facilities have sufficient monitoring of visible emissions to ensure minimal fugitive emissions and the operation of coke ovens at HNR facilities is under negative pressure which prevents excess fugitive emissions.

BENZENE CONCENTRATION ACTION LEVEL

U.S. EPA originally proposed an action level of 3 micrograms per cubic meter (µg/m³) benzene based on modeled fenceline concentrations from emissions inventories associated with data for 2016 and 2022 facility-wide risk assessments; however, U.S. EPA increased the action level in the final rule to 7 µg/m³ as a result of comments received regarding the unique layout of coke oven sources and the elongated shape of facility fencelines, which do not allow a sufficient receptor grid to accurately estimate the maximum ambient concentrations. This action level is intended to reflect fugitive emissions sources only and exclude background concentrations. A facility would exceed this action level when the highest of the rolling annual average fenceline concentrations (corrected for background) is greater than 7 µg/m³. Additionally, the final rule allows for reduced sampling if every sample at a monitoring site is below 0.7 µg/m³ for two years (i.e., 52 consecutive sampling events).

To account for background, each facility will determine a delta concentration (Δc), calculated as the lowest benzene sample value subtracted from the highest benzene sample value for each two-week period. This approach is intended to subtract out any estimated contribution from background emissions that do not originate from the facility. U.S. EPA is also allowing for near-field source correction which requires coke oven facilities to implement a site-specific monitoring plan (SSMP) that documents how the facility will calculate reductions in monitored benzene concentrations from non-coke oven contributions by utilizing additional benzene monitoring and on-site meteorological data. In the case of additional monitoring for near-field source correction, the proposed monitoring could be more frequent passive sampling or near-real time monitoring. If near-real time monitoring is employed, the proposed technology must consistently achieve results for benzene at or below 0.7 µg/m³.

If the rolling annual average exceeds the concentration action level, the coke oven facility must initiate a root cause analysis within five days of calculating the rolling annual average to determine the primary and contributing causes of the exceedance. This root cause analysis must be completed within 45 days of initiation, followed by the corrective action plan to reduce emissions. The coke oven facility would not be deemed out of compliance with the proposed concentration action level if appropriate corrective action measures are taken.

DATA REPORTING

To report and submit results, coke oven facilities will be required to calculate a rolling annual average within 30 days of completion of each sampling episode and report the data for each sampler within 45 days of the end of each quarterly period using U.S. EPA’s public electronic reporting and data retrieval portal. This submittal will include the individual results from each sampler, coordinates of all sampler locations, biweekly 12-month rolling average concentration values, and notes for each value (e.g., background corrections used, if the value was under detection, or an outlier that was removed from the data set). Reporting will start after the first full year of data is collected (i.e., within 45 days from the completion of the 26th biweekly sampling event).

WHAT DOES THIS MEAN FOR MY FACILITY?

Following collection of a year’s worth of data to generate a rolling annual average, your facility will need to demonstrate compliance with the action level within three years following the effective date of the final NESHAP rule (July 15, 2027).

U.S. EPA estimates costs for fenceline monitoring to be $107,000 per year; however, these costs do not include effort associated with development of a monitoring plan, data assessment, quarterly reporting, root cause and corrective action, the possibility of an SSMP, or other quality assurance activities.

HOW CAN ALL4 HELP?

As your facility advances closer toward implementation of benzene fenceline monitoring, do not hesitate to ask for assistance. ALL4 would be glad to discuss any of the following:

• Conducting a pilot study to determine if your facility has excessive benzene emissions ahead of the required monitoring.
• Developing an air monitoring plan.
• Developing an SSMP for near-field source correction.
• Installation and placement of passive samplers to meet the proposed rule.
• Installation and placement of additional benzene sampling methodologies for near-field source correction.
• Collecting, processing, and submitting samples.
• Training for facility personnel.
• Creation of tools to record bi-weekly data and calculate annual rolling averages.
• Analyzing raw data to subtract out background concentrations as appropriate.
• Installation and maintaining meteorological equipment for on-site ambient meteorological data (for SSMP source correction).
• Conducting quality assurance audits to verify the collection of representative samples.
• Preparing electronic reports for U.S. EPA.
• Preparing root-cause analysis and corrective action plans to submit to U.S. EPA if the facility exceeds concentration action level.

We can also help with strategy around implementation of the many other requirements U.S. EPA has added to the NESHAP (e.g., new standards, electronic reporting, and removal of startup/shutdown/malfunction exemptions). For more information on Benzene Fenceline Monitoring please contact Dustin Snare at dsnare@all4inc.com / 610.422.1126 or Kyle Hunt at khunt@all4inc.com / 512.705.0123.