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November 14, 2013
Residual risk review clears foam MACT

After conducting a residual risk and technology review (RTR) of its 1998 maximum achievable control technology (MACT) standards covering emissions of hazardous air pollutants (HAPs) from the flexible polyurethane foam (FPUF) production industry category, the EPA is proposing to prohibit the use of HAP-based auxiliary blowing agents (ABAs) for slabstock foam production facilities.  If finalized as proposed, the prohibition would have no practical effect on those facilities, says the EPA, since they have discontinued the use of HAP ABAs.  However, the EPA believes the prohibition is in order to eliminate the possibility that facilities might begin to use HAP ABAs again.

The Clean Air Act requires that the EPA conduct RTRs no less than 8 years after issuance of a MACT standard to ensure that the standard is protective of the public health with an ample margin of safety and to determine if technological improvements warrant revision.  The RTR determined that the standard was meeting the health-based criteria with an ample margin of safety and that no revision is needed.  The technology review focused on HAP ABAs, diisocyanate storage vessels, and equipment leaks. 

Based on the reviews, the EPA is proposing several additional revisions to the 1998 MACT, including a time requirement on repairing leaks; elimination of the start-up, shutdown, and malfunction exemption; and electronic submission of performance test data.

Affected facilities

There are three types of FPUF producers in the source category:

  • Slabstock
  • Molded
  • Rebond

According to the EPA, in the past decade, the FPUF production source category has been heavily affected by plant closures and consolidations. The Agency states that there are currently 7 slabstock, 6 molded, and 2 rebond FPUF production facilities subject to the MACT standards.

One part of the FPUF production process, particularly for slabstock foams, employs ABAs to produce specific densities and grades of foam where gases produced by the isocyanate-water reaction are insufficient to achieve the desired density. 

The 1998 MACT, which applied equally to new and existing sources, resulted in reductions in HAP emissions from affected sources from 19,700 tons per year (tpy) to 51 tpy, a 99 percent drop.  The MACT also placed limits on emissions of HAP ABAs but did not prohibit their use.  According to the Agency, under the existing MACT, those possible emissions are estimated at 735 tons of HAP ABAs. If the prohibition on HAP ABAs is adopted, no emissions of HAP ABA would be allowed.

Additional proposals

In addition to prohibiting the use of HAP ABAs, the EPA is proposing to:

  • Eliminate the exemptions during periods of start-up, shutdown, and malfunction to ensure the standards are consistent with the District of Columbia Circuit Court’s vacatur of similar provisions in other rules.  
  • Add provisions for affirmative defensethat would shield sources from monetary penalties for excess emissions beyond their control if specified conditions were met.
  • Add requirements for reporting of performance testing through EPA’s Electronic Reporting Tool.
  • Revise compliance dates for applicable proposed actions.
  • Clarify the leak detection methods allowed for diisocyanate storage vessels at slabstock foam production facilities.
  • Add a schedule for delay of leak repairs for valves and connectors.

The proposal was published in the November 4, 2013, FR.

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