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July 14, 2011 

Attention Docket Numbers: 

EPA-HQ-OAR-2002-0058; 

EPA-HQ-OAR-2006-0790; and 

EPA-HQ-OAR-2003-0119 

EPA Docket Center 

EPA West Building 

Room 3334 

1301 Constitution Avenue, NW 

Washington, DC 20005 

Dear Sir or Madam: 

On behalf of the National Association of Clean Air Agencies (NACAA), we 

are writing to you regarding EPA’s National Emission Standards for Hazardous Air 

Pollutants for Institutional/Commercial/Industrial Boilers and Process Heaters 

(Boilers) and Standards of Performance for New Sources and Emission Guidelines 

for Existing Sources: Commercial/Institutional Solid Waste Incinerators (CISWI). 

Along with the publication of the final rules in the Federal Register on March 21, 

2011, EPA also announced the commencement of a process to reconsider 14 topics 

relating to the regulations. While the agency did not solicit public comment on the 

scope of any additional issues that should be reconsidered, it did indicate that it was 

still evaluating whether to reconsider additional issues and that it would review any 

petitions for reconsideration filed with respect to the final rules before making its 

decision on the scope of the reconsideration. On May 18, 2011, EPA published in 

the Federal Register a delay of effective dates of the Boiler and CISWI standards 

and solicited additional data and information from the public. The deadline for any 

additional data and information is July 15, 2011, while the delay of effective dates 

“will remain in place until the proceedings for judicial review are completed or the 

EPA completes its reconsideration of the rules, whichever is earlier.” On June 24, 

2011, EPA filed a Reply in Further Support with the DC Circuit Court of Appeals 

that advised the public that it anticipated issuing proposed revisions to the 

published rules by the end of October 2011 and final rules by the end of April 

2012. 

NACAA has an interest in the development of rules governing toxic 

emissions from Boilers that protect public health as well as the timely and effective 

implementation of these rules. In addition to the paramount importance of public 

health protection, section 112(j) of the Clean Air Act (CAA) provides that where 

EPA fails to implement a Maximum Achievable Control Technology (MACT) 
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standard in a timely manner, state and local permitting authorities must develop and implement 

equivalent limitations on a case-by-case basis. Since the Boiler MACT was overturned and 

vacated by the courts, EPA has already missed the relevant statutory deadline. Further delay 

resulting from the stay issued by EPA or occasioned by a second adverse ruling by the courts 

could substantially increase the likelihood that state and local permitting authorities would be 

required to respond to a greatly increased workload at a time when state and local government 

budgets are severely constrained. For these reasons NACAA urges EPA to conduct its 

reconsideration in a scientifically-defensible manner with the impact on public health as its 

highest consideration. The reconsideration should be conducted in a manner that minimizes the 

risk of significant delays that would occur if the rule is overturned for procedural or substantive 

deficiencies. Finally, the reconsideration should be conducted in a timely and efficient manner. 

NACAA believes that EPA should include in its reconsideration any final MACT 

emission limitation determinations that are substantially different from the proposed limitations, 

irrespective of the reason for the change. A thorough examination of test data and defensible 

emission limitation determinations are mandatory in these cases. This step is necessary and 

appropriate to ensure that the final rules are not overturned on procedural grounds and to provide 

the highest level of confidence that the final emission limitations are protective of public health 

and compliant with the requirements of the CAA. By way of example we note that EPA’s final 

carbon monoxide emission limit for biomass “fuel cell” units is set at 690 ppm, a large increase 

from the proposed 270 ppm limit, and that the final dioxin/furan limit is set at 4 ng/dscm, 400 

times greater than the proposed limit. Based on the record at the time of proposal, reviewers 

could not have foreseen such large changes in the final rule and would tend not to closely 

examine emission levels that were in the same range as other subcategories or comment thereon. 

Similarly, the data associated with the recently published electric generating unit (EGU) 

MACT, which was not readily available to the public during the comment period for the Boiler 

MACT rule, demonstrate the significant adverse impact on calculated MACT floor levels of 

EPA’s inconsistent decisions with respect to determining the performance level achieved by the 

“best performing units.” NACAA also notes that EPA used a different approach in calculating 

variability in the EGU MACT proposal than in the Boiler MACT proposal. NACAA believes 

that EPA should reconsider its procedures for determining variability factors assigned to the best 

performing units. EPA should recalculate MACT floors for Boilers by developing a variability 

factor that does not include inter-unit variability. Differences in performance between units in 

the best performing 12 percent of a subcategory are addressed by the CAA’s obligation to 

average the performance of the best performing 12 percent in establishing MACT floors. This 

factor should not be included a second time in the calculation of the variability factor. 

NACAA is generally concerned that the proposed approach of only reconsidering 

portions of the rule will increase the possibility that the rule may be overturned on procedural 

grounds. Since EPA anticipates that its reconsideration will take more than 13 months, we 

suggest that EPA announce that it is reconsidering all aspects of the rule and accept comments on 

all relevant issues. 
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Thank you for this opportunity to provide you with our initial comments regarding the 

reconsideration of the Boiler and CISWI rules. We look forward to submitting additional 

comments as the reconsideration process progresses. 

Sincerely, 

 

 

S. William Becker