In December 2024, the U.S. Environmental Protection Agency (EPA) proposed amendments to the 40 CFR 63 Subpart PPP: National Emission Standards for Hazardous Air Pollutants (NESHAP) for the Polyether Polyols Production Industry driven by EPA’s completion of the Risk and Technology Review (RTR) for this source category. Polyether polyols (PEPO) are used in the making of lubricants, adhesives, sealants, cosmetics, soaps, and as feedstock polymers for urethanes production. These compounds are derived from the polymerization of EO, PO or other cyclic ethers with compounds having one or more reactive hydrogens to form polyethers. 40 CFR 63, Subpart PPP regulates the collection of polyether polyol manufacturing process units (PMPUs), and associated equipment located at Title V major sources of hazardous air pollutants (HAPs).
 
As with recent updates to 40 CFR 63, Subparts F, G, H and FFFF, EPA has concluded that residual risk associated with the PEPO Production source category are unacceptable, primarily driven by the lowered IRIS value for ethylene oxide (EtO). Additionally, the technology review has resulted in updates to work practices, processes, and control technologies for key emission sources, including process vents, storage vessels, heat exchange systems, and equipment leaks. A summary of these proposed regulatory updates is provided below:
 

EtO Focused Amendments

Based on these reviews, the EPA is proposing a slate of EtO control provisions emissions, separate from the epoxide HAP reduction standards, with these updates either referencing or mirroring EtO requirements under the HON (40 CFR 63, Subparts F/G/H). A summary of key proposed EtO provisions include:
 

• • New Process vent and storage provisions, including:
    • Process vent control triggers at EtO emissions of 1 ppmv and 5 lb/yr (combined, process unit total), with strict limits (e.g., 99.9% reduction)
    • Storage vessel control triggered at 0.1 wt% EtO, with more strict limits (e.g., 99.9% reduction)
    • Enhanced monitoring of control devices, with additional parameters and 1-hr averages for compliance
    • Cannot use extended cookout or production-based limit option for EtO compliance
    • Stack testing required for each EtO control device, conducted every 5 years
    • Requirement to treat surge control vessels and bottoms receivers as process vents

• LDAR standards for EtO, with more frequent monitoring and lower leak levels for valves, connectors, and pumps containing process streams with 0.1 wt% EtO
• Modified El Paso Method monitoring for heat exchanger leaks with process fluids containing >0.1% EtO
• HON EtO wastewater standards, requiring sampling to determine subject streams, a 1 ppmw control threshold, and requirement to follow HON Group 1 wastewater management standards and treat to less than 1 ppmw EtO.
• EtO fenceline monitoring requirements, allowing sources to account for offsite impacts but not allowing sources to discount impacts from non-PEPO operations onsite.

Epoxide and Non-Epoxide HAP Updates

In addition to the new EtO standards, EPA is also proposing revisions to the standards for epoxide and non epoxide HAP, pulling in similar changes made in the HON with some source category specific adjustments. EPA has also proposed new standards related to removal of the SSM exemption, adding several of the changes from HON to the SSM-related changes already made in the 2014 rule update. Key changes include:
 

• Addition ofbutylene oxide to the list of epoxide HAP
• Removal of exclusions from the affected source for processing steps after epoxide polymerization and for catalyst removal, such that the process vent standards, including those for EtO, now apply for all reaction and processing steps.
• Lower and simplified Group 1 non epoxide HAP thresholds for batch process vents (10,000 lb/yr) and continuous process vents (1 lb/hr HAP), with removal or prior exemptions.
• Require surge control vessels and bottoms receivers by treated as process vents.
• Add maintenance vent work practice standards for opening of process vessels
• Specify Modified El Paso Method for heat exchange leak monitoring, allowing other methods for certain highly soluble HAP process streams, and updates to source category applicability criteria
• For Group 1 Storage Vessel, lowered control triggers, new degassing standards, and level change prohibitions during planned routine maintenance
• Removing exemptions for pressure vessels and require that vessel components operate with no detectable emissions, as verified by initial and annual Method 21 monitoring, and requiring any releases to the atmosphere be routed to controls.
• Lower 100 ppmv leak threshold for valves in light liquid and gas/vapor service
• Revise closed vent system bypass requirements
• MACT CC flare requirements
• New standards for transfer racks loading material into tank trucks and railcars, including PEPO specific Group 1 threshold (0.5 psia) and control standards for existing sources
• Design standard and monitoring requirements for nonregenerative carbon systems
• CEDRI reporting

The public comment period for these amendments is currently ongoing with EPA accepting comments from facilities until February 25, 2025.
 
Following EPA’s typical schedule, these amendments will likely be finalized no later than 1st quarter 2026, with compliance dates two (2) years (EtO provisions) to three (3) years after the effective date of the final rule. Trinity strongly encourages the regulated community to review the proposal to understand the magnitude of these proposed changes and to comment, either directly or through industry groups, on any items that are problematic for your Sites. Trinity is available to assist our clients through this process, as needed, to ensure that EPA’s proposal receives necessary feedback from the regulated community in the comment period, and we are available to assist with implementation of the finalized amendments.
 
For more information and assistance evaluating your current compliance requirements, please contact David Dempsey 630.495.1470 or Gena Driscoll 251.391.5789 –>