Proposed Amendments to National Emission Standards for Hazardous Air Pollutants: Rubber Tire Manufacturing

On November 16, 2023, the U.S. Environmental Protection Agency (U.S. EPA) published a proposed rule that would establish first time emissions standards for the rubber processing subcategory in the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Rubber Tire Manufacturing (40 CFR Part 63, Subpart XXXX). This is the only subcategory in the Tire NESHAP that currently has no emissions standards. With the proposed rule, U.S. EPA is responding to the April 2020 decision by the U.S. Court of Appeals for the District of Columbia that obligates U.S. EPA to address unregulated HAP emissions from a source category when the Agency conducts the 8-year technology review required by the Clean Air Act (CAA) Section 112(d)(6).

Does this proposal apply to me?

If you are a HAP major source rubber tire manufacturing facility and you’re reading this article, then you probably already know that your facility is subject to this rule. So, the question then becomes, what part of my process will be subject to the proposed amendments? The subcategory in question here is the “rubber processing” subcategory, which includes rubber mixing. Any rubber mixer on site at your major source facility would be affected by the proposed amendments. Any existing source at the time of the proposed rule (i.e., sources that commenced construction or reconstruction on or before November 16, 2023) would be required to comply with the new standards within 3 years of publication of the final rule, while any source that commenced construction or reconstruction after the proposed rule would have to comply with the new standards upon startup.

What are the Proposed Amendments?

Emissions standards

To regulate the emissions of HAP from rubber mixing, U.S. EPA has proposed to set limits on total hydrocarbons (THC) and filterable particulate matter (fPM). U.S. EPA is proposing to use THC as a surrogate for organic HAP and fPM as a surrogate for metal HAP. U.S. EPA is proposing separate THC emissions limits for silica containing tire compounds and non-silica containing tire compounds based on the Agency’s assertion that there is a difference in emissions between the two. The limit proposed for existing sources is 9.4 grams of THC per megagram (g THC/Mg) rubber processed for silica-containing compounds and 45.4 g THC/Mg rubber processed for non-silica containing compounds, both on a 15-day rolling average. New sources have more stringent proposed limits based on the single best performing mixer from the dataset U.S. EPA reviewed. These limits are 2.1 g/Mg for silica-containing compounds and 17.2 g/Mg for non-silica containing compounds. U.S. EPA is proposing a fPM limit of 1.70 g fPM/Mg rubber processed or 0.37 g metal HAP/Mg rubber processed. These proposed limits would apply to both new and existing sources and the facility has the choice to decide which one to comply with.

Initial and Continuous Compliance Requirements

Initial compliance with the new emissions limits would be demonstrated via performance testing within 180 days of startup for new sources and within 3 years of the date of the final rule for existing sources. U.S. EPA is proposing that sources would conduct subsequent performance tests every five years. Additionally, U.S. EPA is proposing that a THC continuous emissions monitoring system (CEMS) must be installed at each mixer exit to continuously monitor THC emissions. U.S. EPA is also proposing that facilities would be required to monitor and record their production rate and type (e.g., lb/hr and silica or non-silica) in order to calculate production-based THC emissions on a 15-day rolling average. There are no emissions averaging provisions proposed, so compliance would be demonstrated for each individual mixer.

If facilities use a thermal oxidizer to control THC emissions, U.S. EPA is proposing that, in addition to a THC CEMS, sources will be required to continuously monitor the firebox temperature and maintain the temperature above the level established during the performance test on a daily average basis. U.S. EPA is also proposing that facilities install and operate a bag leak detection system (BLDS) on any fabric filters used to control fPM/metal HAP emissions. Compliance reports and notifications will be submitted electronically through U.S. EPA’s Compliance and Emissions Data Reporting Interface (CEDRI).

What’s next?

Comments are due to U.S. EPA on the proposed rule by January 2, 2024, although it is likely that commenters will request a comment period extension given the volume of data required to be reviewed and the impending holidays. U.S. EPA has not yet analyzed all emissions data received from their information collection request (ICR) and must do so (as well as analyze any data received during the comment period) before publishing a final rule; therefore, we expect the standards may change significantly in the final rule. Once the final rule is published, each major source facility with rubber mixers will need to determine what new standards and requirements apply and how to comply with them by the compliance date. ALL4 can assist facilities with understanding these new regulatory requirements, planning for compliance, reviewing emissions test data, obtaining vendor quotes for new emissions control systems, setting up new monitoring systems, establishing electronic compliance systems, and compliance reporting. If you have any questions, feel free to reach out to me at bjohnson@all4inc.com or (502) 874-4500 or to Philip Crawford at pcrawford@all4inc.com or (984) 777-3119.