Boiler MACT Remanded to EPA

April 27, 2018Newsletters
The AIR QUALITY Letter: April 2018

The Boiler MACT rulemaking saga continues as a result of the March 16, 2018 D.C. Circuit decision in Sierra Club v. EPA. The Sierra Club had challenged revisions to certain requirements in 40 CFR 63 Subpart DDDDD that were promulgated on November 20, 2015. The two issues addressed by the court were: (1) whether the 130 ppm limits on carbon monoxide (CO) as a surrogate for hazardous air pollutants (HAP) were sufficiently supported, and (2) whether the startup and shutdown work practice standards were arbitrary and capricious and contrary to the Clean Air Act. The court remanded the 130 ppm CO limits to EPA for reconsideration but rejected the Sierra Club’s challenge to the startup and shutdown work practice standards.

First, with respect to the CO limits, the court had previously agreed that CO was a suitable surrogate for organic HAP. However, the court had not yet addressed the question of whether the 130 ppm CO limits were appropriate. The court noted that regulation by surrogate is an available tool but the agency decision will be evaluated in terms of whether reducing surrogate emissions will “invariably” and “discriminately” reduce the corresponding HAP. In prior litigation over the rule (United States Sugar Corp. v. EPA, 830 F.3d 579 (D.C. Cir. 2016)), the court found EPA had sufficiently demonstrated a strong correlation between CO and organic HAP but identified a gap in the record over whether the best performing boilers might be using additional controls that reduce organic HAP emissions beyond that achieved by only regulating CO. In the subsequent rulemaking, the agency evaluated the relationship between CO emissions and emissions of formaldehyde and found that aspects of the data were untrustworthy. However, EPA relied on the same data to justify its conclusion that lower CO limits would not yield further reductions in organic HAP. The court remanded the 130 ppm CO limits to the agency for re-evaluation but did not vacate them.

With respect to the revised startup and shutdown work practice standards that were included in the 2015 amended rule, the court found EPA’s decision was adequately supported. The startup definition in the revised rule provided that startup ended four hours after the boiler first supplies useful thermal energy. The court upheld the definition over Sierra Club’s objection that the four-hour window for startup was too lax. The court noted that the revised rule established additional requirements, including use of clean fuels during startup and development of written startup and shutdown plans. A faster startup definition, with the incentive of reduced recordkeeping and reporting obligations, was included as an option for boilers that were capable of earlier stabilization. In upholding the revised provisions, the court noted that EPA’s authority to resort to a work practice standard does not require it to establish its appropriateness for every single source to which a work practice applies, rather EPA is entitled to look at the class of sources in issue. Additionally, the court found EPA’s approach was a reasonable accommodation of legitimate safety concerns in deciding what work practices were achievable. The requirement for written plans that are subject to public inspection and enhanced recordkeeping requirements provide an additional check on the accuracy of boiler operators’ assertions about what is possible. The court also rejected Sierra Club’s attack on the shutdown provisions of the rule.

In summary, the startup and shutdown work practice standards in the rule have been upheld. EPA must take another look at its support for adopting the 130 ppm CO limits but the existing regulatory limits remain in effect in the interim.


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