Boiler MACT Reconsideration and Proposed Amendments

On December 1, 2014, the U.S. Environmental Protection Agency (EPA) announced the reconsideration of and proposed amendments to the National Emission Standards for Hazardous Air Pollutants for Major Sources: Industrial, Commercial, and Institutional Boilers and Process Heaters (Boiler MACT), 40 CFR 63 Subpart DDDDD. The proposed amendments represent technical corrections and clarifications to the final version of the Boiler MACT rule that was published January 31, 2013. EPA is soliciting comment on whether the proposed changes, which are intended to correct inaccuracies and oversights promulgated in the final Boiler MACT rule, provide the intended accuracy, clarity, and consistency.

Proposed Amendments

The proposed amendments do not affect the applicability of the final rule. Rather, these updates are intended to streamline the ability of owners and operators of affected sources to understand and comply with the requirements. In addition to correcting typographical errors, erroneous equation references, and other incorrect regulatory references, the following changes are represented in the recently proposed amendments to the Boiler MACT rule:

Applicability and Exemptions

  • “Temporary process heaters” and “residential boilers” are both exempt from Boiler MACT requirements. (The current rule only includes an exemption for “temporary boilers.”)
  • “Temporary process heaters” are included under the existing definition for “temporary boilers.”
  • The term “residential boiler” is defined as follows: a boiler used to provide heat and/or hot water and/or as part of a residential combined heat and power system. This definition includes boilers located at an institutional facility (e.g., university campus, military base, church grounds) or commercial/industrial facility (e.g., farm) used primarily to provide heat and/or hot water for: (1) A dwelling containing four or fewer families; or (2) A single unit residence dwelling that has since been converted or subdivided into condominiums or apartments.
  • The exemption for Commercial/Industrial Solid Waste Incinerators (CISWI) clarifies that, if a unit ceases combusting solid waste, then the unit is no longer subject to NSPS Subpart CCCC or DDDD requirements for CISWI units. (While the current rule states that such units must meet Boiler MACT requirements, it does not explicitly state that these units are no longer subject to the NSPS Subparts.)

EQ Winter 2015 - Boiler MACT

Compliance Dates

  • The proposed compliance date for new and reconstructed units is April 1, 2013, or upon unit startup, whichever is later. (The current rule identifies a compliance date of January 31, 2013.)
  • If a fuel switch or physical change to an affected unit triggers the applicability of a different sub- category of units after January 31, 2016, then the unit must be in compliance with relevant existing source provisions on the effective date of the fuel switch or physical change. Similarly, if such a change is made to a new unit after the 2013 compliance date, then the unit must be in compliance with the applicable new source provisions on the effective date of the change. (While the current Boiler MACT rule includes notification requirements for fuel switches or physical changes, the proposal also details initial compliance requirements for these changes).

Emission Limitations

  • Proposed steam output-based limits provide an alternative for units that generate steam, cogenerate steam with electricity, or both. Boilers that perform multiple functions (e.g., cogeneration and electricity generation) or supply steam to common heaters must determine compliance with the total steam energy output-based limits using Equation 21. However, the electricity output-based limits are applicable to boilers that generate only electricity. (The current rule does not specify how these alternative output-based limits apply to units with multiple functions, and does not include Equation 21.)
  • The proposal excludes the affirmative defense provisions for violations of emission standards during malfunction conditions. (The removal of this provision is based on an April 2014 DC Circuit Court ruling.)

General Compliance Requirements

  • If subject to an emission limit under the Boiler MACT rule, a facility must develop and implement a written startup and shutdown plan (SSP), to be maintained onsite and available upon request. (The current rule does not include an SSP requirement.)

Testing, Fuel Analyses, and Initial Compliance Requirements

  • If an affected source switches unit subcategories after the initial compliance date, then the unit must demonstrate compliance with the requirements that apply to the new subcategory within 60 days of the switch, unless a previous compliance demonstration for this subcategory was conducted within the preceding 12 months. (The current rule does not specify initial compliance requirements associated with these subcategory switches.)
  • The proposal excludes the provision in the composite fuel sampling section that requires monthly composite samples to be collected at approximately equal 10-day intervals during the month.
  • A facility may demonstrate that a gaseous fuel qualifies as an “other gas 1 fuel” by measuring mercury concentrations in the exhaust gas when only the fuel under consideration is being fired, as an alternative to conducting fuel specification analyses for mercury when such a fuel analysis is not practical. (The current rule only allows fuel analysis to make this demonstration.)
  • The proposal removes the requirement to submit a site- specific fuel analysis plan for “other gas 1 fuels” to EPA for review and approval.
  • If a facility chooses to establish compliance with a CO emission limit using a Continuous Emissions Monitoring System (CEMS) rather than source testing, then it may use a CO2 analyzer instead of an oxygen analyzer. If a CO2 analyzer is used, rather than adjusting hourly CO concentration measurements from the CEMS to a 3 percent oxygen basis to demonstrate compliance with the emission limit, the CO readings must be corrected to a “CO2 percentage determined to be equivalent to 3 percent oxygen.” This relationship must be established during the initial compliance test.
  • If a facility is subject to a CO emission limit and chooses the CEMS alternative compliance option, such that CO stack testing is not required, then it must set the oxygen level of the required oxygen trim system to the concentration measured during the most recent tune-up to optimize CO to manufacturer’s specifications. (The current rule specifies that the oxygen level should be set based on the most recent performance test, however performance testing is not required if the CEMS alternative is selected.)
  • If a pH monitoring system is used, this system must be calibrated in accordance with the site-specific monitoring plan at least once each process operating day. (The current rule requires daily “performance evaluations,” rather than calibrations.)
  • If an SO2 CEMS is used to demonstrate compliance with an applicable HCl emission limit, then the facility may install, certify, operate, and maintain the CEMS according to either 40 CFR 60 or 40 CFR 75. (The current rule only references Part 75 requirements.)
  • For establishing the maximum pollutant input levels (if performance testing is used to demonstrate compliance with HCl, mercury, or Total Selected Metals (TSM) emission limits), the heat input fractions used in Equations 7 through 9 should correspond to the fuel mixture that has the highest pollutant concentration during the initial compliance test. Furthermore, for demonstrating continuous compliance with these pollutant input levels, the heat input fractions should be based on the actual fractions of fuel burned during the month. (The current rule does not include this detail regarding the heat input fractions used in Equations 7 through 9.)
  • The Notification of Compliance Status must include a signed certification that the energy assessment is “an accurate depiction of your facility at the time of the assessment” or "that the maximium number of on-site technical hours specified in the definition of energy assessment applicable to the facility has been expended.” (The current rule does not require either of these certifications).

EQ Winter 2015 - Boiler MACT Quote

Continuous Compliance Requirements

  • Monitoring system data recorded during periods of startup and shutdown, as well as during malfunctions, out-of-control periods, associated repairs, or required QA procedures, may not be used in data averages and calculations to report emissions or operating levels. (The current rule does not include periods of startup and shutdown in this list of excluded monitoring data.)
  • Tune-ups must be conducted while burning the type of fuel (or fuels, if the unit burns a mixture) that provided the majority of the unit’s heat input over the preceding 12 months. (The current rule does not specify the type of fuel to be used during tune-ups.)

Notifications, Reports and Records

  • The proposal adjusts the semi-annual compliance periods for reporting from ending on July 31 and January 31, to ending on June 30 and December 31.
  • A facility must identify deviations from required work practice standards during periods of startup and shutdown in the compliance report. (The current rule does not require these deviations to be identified in the compliance report).
  • The proposal clarifies report submittal requirements. Specifically, for data collected using test methods supported by EPA’s Electronic Reporting Tool (ERT), as listed on the ERT web-site, the facility must submit the test results to EPA through the Compliance and Emissions Data Reporting Interface (CEDRI). As an alternative to submitting test data in a file format generated through ERT, a facility may submit an alternative electronic file format consistent with the extensible markup language (XML) schema that will be listed on the ERT website when it becomes available. Otherwise, for data collected using test methods not supported by EPA’s ERT (not listed on the ERT web-site), a facility must submit the test results to the Administrator at the listed address.
  • This proposal also clarifies requirements for submitting confidential business information (CBI), and specifies that a facility must begin submitting reports via CEDRI no later than 90 days after the relevant reporting form becomes available in CEDRI.
  • For each startup period, a facility must maintain specific records including the times that clean fuel combustion begins and ends; the time that PM controls are engaged; the hourly steam temperature, pressure, flow rate, etc.; and certain control device operating data. (The current rule only requires records of the date and time of each startup, and records of fuel type(s)/amount(s) used during each event.)
Other Requirements and Information
  • The proposal excludes the definition for “affirmative defense”; includes definitions for “fossil fuel” and “useful thermal energy”; and expands the definitions of “load fraction” for co-fired units, “oxygen trim system,” “startup,” “shutdown,” and “steam output.” Furthermore, the expanded definition for “steam output” includes a new equation for calculating the total steam output for a multi-function boiler.
  • The proposal updates the numerical CO emission limits for hybrid suspension grate units designed to burn biomass.
  • The proposal expands the list of allowable startup fuels.

With the reconsideration, EPA is considering some alternatives and flexibilities that were proposed by the regulated community. Specifically, EPA is requesting public comment on three specific issues raised in the petitions for reconsideration:

  • Clarifying the definition of startup and shutdown periods, as well as the work practices that apply during these periods
  • Revising carbon monoxide (CO) emission limits based on a minimum level of 130 parts per million by volume (ppmv) at 3 percent oxygen
  • The use of particulate matter continuous parameter monitoring systems (PM CPMS) to demonstrate compliance with PM limits, including the consequences of exceeding the relevant operating parameter(s)

EPA is accepting comments on this proposal for 45 days after the notice is published in the Federal Register (Note: As of March 1, 2015, this notice has not yet been published in the FR.) In spite of these changes, EPA has not proposed extending the compliance date for existing sources beyond the current regulatory deadline (January 31, 2016). EPA has the proposed rule (pre-publication version), as well as a red-line/strike-out versions of the full Boiler MACT regulation, available at its website:

Facilities with existing boilers and process heaters that are subject to the Boiler MACT rule should ensure that they have a plan in place to demonstrate initial compliance, including completing required energy assessments and initial tune-ups, by January 31, 2016. These sites will have 180 days from this date to complete all required performance stack testing and monitoring system performance evaluations. Affected facilities should review the proposed Boiler MACT amendments to determine whether these changes, if finalized by EPA, will impact a facility’s anticipated compliance plan.