USEPA Proposes Revisions to Boiler and Incinerator MACT Rules

On December 2, 2011, the United States Environmental Protection Agency (USEPA) announced a proposal to revise its hazardous air pollution rules related to major source boilers, area source boilers and solid waste incinerators. These proposed revisions stem from a reconsideration of the boiler and incinerator standards promulgated by USEPA on March 21, 2011 (commonly referred to as the Boiler MACT). USEPA stated that it revised the rules based on new data it received during the reconsideration process, and that it seeks to improve the achievability of standards, better reflect real-world operating conditions, allow more flexibility to operators, and reduce the costs of compliance for affected sources. The rules apply to most boilers and incinerators, with some exceptions (for example, the major source boiler standards do not apply to electric steam generating units).

There has been recent legislation seeking to delay the effective date of any new hazardous air pollution standards for boilers and incinerators. In October, the U.S. House of Representatives passed legislation that would stay the March 2011 boiler and incinerator rules and prevent USEPA from adopting any revised air standards for boilers and incinerators until 15 months after enactment of the legislation. This legislation would also provide industry with five years to comply with any revised standards that are promulgated rather than the three years currently allowed under the Clean Air Act. The Senate has not yet voted on the bill. Despite the proposed revisions to the March 2011 rules, which are described in further detail below, several industry groups and legislators continue to support this legislation and continue to urge the Senate for its passage. The White House has indicated that it will veto the bill if it passes in the Senate.

Major Source Boiler Standards

The proposed major source boiler revisions impact large industrial, commercial and institutional boilers, and process heaters that have the potential to emit either 10 tons/year or more of any Hazardous Air Pollutant (HAP) or 25 tons/year or more of any combination of HAPs. USEPA has stated that under the proposed changes, emissions reductions for mercury, hydrogen chloride, and sulfur dioxide would be higher than under the March 2011 rule; however, emissions reductions for air toxics metals, particulate matter, and volatile organic compounds would be lower than under the March 2011 rule. Examples of the proposed revisions include:

• Replacing numeric emissions limits for dioxins/furans with work practice standards;
• Setting new emissions limits for particulate matter and carbon monoxide based on variability between different types of fuel sources and boilers, respectively;
• Creating new subcategories for hybrid suspension/grate biomass units, limited-use units, solid fuel units, and non-continental liquid units;
• Allowing certain subcategories of units greater flexibility in measuring HAPs by allowing them to choose between using either alternative total selective metals emissions or particulate matter emissions as a surrogate for the measurements;
• Removing the continuous emissions monitoring requirements for particulate matter pollution at biomass units;
• Ensuring good combustion by requiring the installation, calibration, monitoring and use of oxygen trim systems to optimize air-to-fuel ratio and combustion efficiency at units, rather than requiring monitoring of oxygen levels;
• Using a 30-day rolling average for parameter monitoring and demonstration of continuous compliance with operating limits rather than the 12-hour block averages that correspond to the expected length of the longest duration 3-run emission test that was required to demonstrate initial compliance with emission limits; and
• Eliminating the requirement that hydrogen sulfide fuel be used as an indication of potential HAPs in order for units burning clean gases to qualify for work practice standards rather than numeric emission limits (instead, units may demonstrate that gas is clean by considering only mercury).

Area Source Boiler Standards

USEPA's proposed area source boiler revisions impact boilers that do not fit the description of a major source boiler. Some of USEPA's proposed revisions to the area source boiler standards include:

• Postponing the date by which area sources have to perform their initial compliance demonstration with the area source rules to March 2013, instead of March 2012;
• Creating a new subcategory for seasonally operated boilers and allowing seasonal operators to conduct tune-ups every five years after the initial compliance demonstration rather than every other year;
• Exempting temporary boilers from the area source rule; and
• Providing a 30-day rolling average for parameter monitoring and compliance with operating limits.

Solid Waste Incinerator Standards

The proposed solid waste incinerator revisions impact devices that are used to burn solid waste at commercial or industrial facilities, including incinerators, energy recovery units, waste burning kilns, and small, remote incinerators. Some of USEPA's proposed revisions to the incinerator standards include:

• Adjusting emissions limits for waste-burning cement kilns and for energy recovery units so that they reflect information regarding newly identified units and additional data received by USEPA;
• Removing oxygen correction requirements for carbon monoxide emission limits at energy recovery units during startup; and
• Including a clarification regarding what units would be considered commercial and industrial solid waste incineration units.

Comments on the proposed revisions will be due 60 days from their publication in the Federal Register. USEPA has said that it plans to finalize the revised rules by Spring of 2012. Complete versions of the proposed revisions can be found at http://www.epa.gov/airquality/combustion/actions.html.

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