See the latest EHS federal and state regulatory updates due to COVID-19

On December 23, 2011, and in parallel with the Boiler National Emission Standards for Hazardous Air Pollutants (NESHAP) Rules and the Non-Hazardous Secondary Material (NHSM) Rule updates, EPA proposed amendments to the Standards of Performance for New Stationary Sources (NSPS) and Emission Guidelines (EG) for Existing CISWI Units (EG Subpart DDDD), collectively referred to as the “2011 CISWI Rules Revision.”1  The 2011 CISWI Rules Revision will impact any facility that owns an emission unit that “combusts, or has combusted in the preceding six months, any solid waste as that term is defined in 40 Code of Federal Regulations (CFR) Part 241… .”2 In order to determine if an emission unit combusts non-hazardous solid waste, please refer to the article titled Revisions to Non-Hazardous Secondary Materials Regulation on page 14 of this magazine for additional details.

This 2011 CISWI Rules Revision amends final rules that were promulgated on March 21, 2011 (March 21, 2011 CISWI Rules).  Concurrent with promulgating the March 21, 2011 CISWI Rules, EPA also issued a notice of reconsideration to reevaluate specific aspects (e.g., emission limits, monitoring requirements, etc.) of the finalized rules.  EPA is proposing this 2011 CISWI Rules Revision as a result of the reconsideration process.

EPA stayed the effective date of the March 21, 2011 CISWI Rules in the Federal Register on May 18, 2011.  On January 9, 2012, the U.S. District Court of Appeals vacated EPA’s stay, the full impact of which is currently being investigated by EPA, the regulated community, and legal authorities.  EPA has stated that it will issue a “no action assurance letter shortly, informing sources that EPA will not enforce any of the administrative notification requirements for new or existing boilers and incinerators in the 2011 Rules for a period of time while the EPA works to take final action on the proposal to reset these dates.”3 This article provides an overview of the differences between the CISWI NSPS rule and the CISWI EG rule and a summary of the CISWI Rules based on the December 23, 2011 proposal.

NSPS versus EG

As clarified in previous Environmental Quarterly articles on this topic, a new CISWI unit is required to comply directly with the federal regulations provided under 40 CFR Part 60, Subpart CCCC within six months after promulgation of the final rule or upon initial startup, whichever is later.  An existing CISWI unit must comply with state specific regulations that have incorporated the EG (40 CFR Part 60, Subpart DDDD) in a State Plan that has been approved by EPA.  If EPA has not approved the State Plan, the existing CISWI unit must be in compliance with the Federal Plan, as listed in EG Subpart DDDD.  The existing CISWI unit must be in compliance with the EG within three years after EPA approves a State Plan implementing the EG, or five years after the date the EG Subpart DDDD is promulgated, whichever is earlier.

CISWI Rules Summary

Applicability and Exemptions
Under the 2011 CISWI Rules Revision, a CISWI unit will be considered a new unit and therefore subject to NSPS Subpart CCCC if:

  1. Construction commences after June 4, 2010,4 or
  2. Reconstruction or modification commenced after date six months after publication of the final rule in the Federal Register.


A CISWI unit will be considered an existing unit, and therefore subject to the state regulations incorporating EG Subpart DDDD if:

  1. Construction commenced on or before June 4, 2010, or
  2. Reconstruction or modification commenced on or prior to date six months after publication of the final rule in the Federal Register.


Please note that a unit that meets the definition of a new CISWI unit under the 2000 CISWI Rules will be considered an existing CISWI unit under the 2011 CISWI Rules Revision if the unit was constructed on or before June 4, 2010.  However, these units would be required to remain in compliance with the 2000 NSPS emission limits as provided in Table 2, until the units are considered existing sources under the amended standards, which would be three years after EPA approved the State Plan or five years after the publication of the final rule in the Federal Register, whichever is earlier.  State Plans must be submitted to EPA one year after the final rule is published in the Federal Register.

The 2011 CISWI Rules Revision exempts the following sources: pathological waste incineration units, municipal waste combustion units, medical waste incineration units, small power production facilities, cogeneration facilities, hazardous waste combustion units, materials recovery units, air curtain incinerators,5  sewage treatment plants, and sewage sludge incinerators.  Burn-off ovens, chemical recovery units, cyclonic burn barrels, laboratory analysis units, soil treatment units, space heaters, and foundry sand thermal reclamation units, by definition, do not fall into the four CISWI subcategories with established emission limits and thus, are not required to meet emission standards currently established in the CISWI Rules Revision.  Note that as part of the 2011 CISWI Rules Revision, EPA is proposing to add the definition of space heater and foundry sand thermal reclamation unit, and revised the definition of chemical recovery unit, to clarify that these unit types do not fit into one of the four CISWI subcategories.  EPA also reinstated the definition of “contained gaseous materials” into the CISWI rules.  For additional information on the “contained gaseous materials” topic, please refer to the article in this magazine titled Revisions to Non-Hazardous Secondary Materials Regulation on page 14.

Finally, any unit subject to the 2011 CISWI Rules Revision must obtain a Title V operating permit regardless of the potential to emit of any pollutant from the facility.

Waste-to-Fuel Effective Date

Recycled TiresA CISWI unit is defined as any distinct operating unit of any commercial or industrial facility that combusts, or has combusted in the preceding six months, any solid waste as that term is defined in 40 CFR Part 241.  If a facility opts to stop combusting solid waste, the combustion unit would still be subject to the CISWI rules for the subsequent six months.  During this six month time period, the facility would need to review applicable regulations that the emission unit would need to comply with when the unit ceases to combust solid waste (e.g. – if a boiler ceased combusting solid waste and was located at a major source of HAPs, the facility would have six months to bring the unit into compliance with the Boiler MACT while remaining in compliance with the CISWI rules).  The effective date of the waste-to-fuel switch is at least six months from the date that solid waste was last combusted in the emission unit.  Additionally, the facility must notify EPA 30 days prior to the effective date of switching from solid waste to fuel.

EPA identified the fuel switching provisions as one of the topics for reconsideration; however, no changes to this provision are included in the 2011 CISWI Rules Revision.  EPA solicited comment on whether the provisions should include further clarification on the timeline and regulatory requirements of a fuels switch, and on an alternative time period for switching frequency (e.g., 12 months instead of 6 months).

CISWI Unit Subcategories and Emission Limits

The CISWI Rules Revision includes four subcategories: incinerators, energy recovery units (ERUs), waste-burning kilns, and small, remote incinerators.  EPA removed the burn-off oven subcategory in the March 21, 2011 CISWI Rules.  Because this change was made between the 2010 proposed rules and the final March 21, 2011 CISWI Rules, EPA identified the removal of the burn-off oven subcategory as a topic for reconsideration.  However, based on the comments received during the reconsideration process and the lack of emissions data available, EPA is not proposing to add standards for burn-off ovens in the 2011 CISWI Rules Revision.  EPA added fuel specific emission limits for ERUs that combust biomass, coal, or liquid/gas in the March 21, 2011 CISWI Rules, and is proposing biomass/coal specific limits for additional pollutants (Pb, Cd, PM, and dioxins/furans) in the current amendments.  Additionally, the current amendments establish separate CO emission limits for long kilns versus preheater/precalciner kilns in the waste burning kiln subcategory.

The 2011 CISWI Rules Revision establishes emission limits and work practices for the following subcategories:

  1. Incinerators – any furnace used in the process of combusting solid waste for the purpose of reducing the volume of the waste by removing combustible matter.
  2. ERU designed to burn biomass – a combustion unit combusting solid waste for energy recovery.  The ERU must combust biomass or non-coal solid materials, and combust less than 10 percent coal, on a heat input basis on an annual average, either alone or in combination with liquid waste, liquid fuel, or gaseous fuels.
  3. ERU designed to burn coal – a combustion unit combusting solid waste for energy recovery.  The ERU must combust at least 10 percent coal on a heat input basis on an annual average, either alone or in combination with liquid waste, liquid fuel, or gaseous fuels.
  4. ERU designed to burn liquid/gas – a combustion unit combusting solid waste for energy recovery.  The ERU must combust a liquid waste with liquid or gaseous fuels not combined with any solid fuel or waste materials.
  5. Waste burning kilns – a kiln that is heated, in whole, or in part, by combusting solid waste.  The 2011 CISWI Rules Revision includes subcategories by kiln type for CO emissions (long kilns and kilns with preheaters).
  6. Small remote incinerators – an incinerator that combusts solid waste, combusts three tons solid waste per day or less, and is more than 25 miles driving distance to the nearest municipal solid waste landfill.


EPA is proposing revised emission limits for ERUs and waste burning kilns.6  EPA identified eleven new kilns and three new ERUs that needed to be included in the emission limit analysis (i.e., the MACT floor determination) for CISWI units, based on the March 21, 2011 NHSM definition.  Additionally, the revised inventory used to determine the limits in the 2011 CISWI Rule Revisions excluded five ERUs that had been included in the previous inventory, because the units no longer burn solid waste based on the March 21, 2011 NHSM definition.  The proposed updates to the emission limits for these subcategories are based on a revised MACT floor determination using this revised inventory.

Tables 1 and 2 present a comparison between the final limits promulgated in the March 21, 2011 CISWI Rules and the proposed 2011 CISWI Rules Revision for existing and new sources, respectively.  Note that all emission unit categories appear in the tables for completeness, but no changes were made to the small, remote incinerator emission unit subcategory and only minor updates were made to the incinerator category in the 2011 CISWI Rules Revision.

EPA stated that it expects the emission reductions of the nine toxic air pollutants emitted from CISWI units to decrease slightly as compared to the March 21, 2011 limits.7  Accordingly, the majority of the proposed revisions result in higher, less stringent emission limits.  However, emission limits decreased for the following pollutants:

  • HCl from existing waste burning kilns
  • CO from existing coal-fired ERUs
  • Pb from existing solid-fired ERUs (coal and biomass)
  • Pb and Cd from new solid-fired biomass ERUs
  • PM from existing and new solid-fired ERUs
  • Hg from new waste burning kilns

Consistent with the March 2011 final rule, the proposed rule requires that facilities comply with emission limits at all times including periods of startup, shutdown, and malfunction.  EPA is proposing a 7 percent oxygen correction waiver for CO emissions limits during startup and shutdown.  This waiver would apply to CISWI sources that elect to demonstrate compliance with the CO limits with a CO CEMS instead of performing stack tests.

For periods of noncompliance during a malfunction, EPA added language in the March 21, 2011 CISWI Rules allowing a facility to use an affirmative defense to civil penalties resulting from an emission limit exceedance.  To assert the claim of affirmative defense, facilities must meet the notification and evaluation criteria listed in the final rules.  EPA solicited comments on the inclusion of the affirmative defense provisions in the final rule.

Control Devices and Operating Limits

In order to comply with the emission standards provided in Tables 1 and 2, sources will most likely have to install one or more control devices on the CISWI units.  The following parameters must be monitored using a continuous parameter monitoring system (CPMS):

  • Wet scrubbers: charge rate, pressure drop or current, scrubber liquid flow rate, and scrubber liquid pH
  • Fabric filters: bag leak detection system
  • Electrostatic precipitators (ESP): secondary voltage and current
  • Activated carbon sorption injection: sorbent flow rate
  • Selective noncatalytic reduction: charge rate, secondary chamber temperature (if applicable to the unit), and reagent flow rate

If a unit does not use a wet scrubber, ESP, or fabric filter to comply with the PM emission limit and if compliance with the PM emission limit is not demonstrated with a CEMS, then a unit must maintain opacity less than or equal to 10%.  In addition, if a facility uses control devices other than those specified in the standard or limits emissions in some other manner, the facility must submit a petition to EPA requesting approval of proposed operating parameters that will be monitored and the operating limits that will be established (during the initial performance test) to demonstrate compliance with the emission limits.  The petition must be approved by EPA prior to the initial performance testing.  On a somewhat related topic, EPA is considering adding dry sorbent injection for acid gas control as a standard control option specifically listed in the rules.  As such, EPA sought comment on whether this addition is appropriate, and what the relevant monitoring provisions/parameter specifications would be for dry sorbent injection for acid gas control.

Facilities must develop and submit a site- specific monitoring plan for each continuous monitoring system required by the rule.  The plan must be submitted at least 60 days before the initial performance evaluation of the continuous monitoring system.  The rule also includes initial and annual inspection requirements for each control device installed on a CISWI unit.  

Source Testing and Continuous Emissions MonitoringAnnual source tests are required for all CISWI units that have an emission limit unless a CEMS or COMS is used to demonstrate compliance with the respective emission limit.  The annual performance tests must be conducted between 11 and 13 months of the previous performance test.  The annual performance testing requirements and continuous monitoring requirements are identified in Table 3.

Annual performance testing can be reduced to once every three years if test results show emissions at or below 75 percent of the limit for PM, SO2, HCl, NOX, Pb, Cd, Hg, and dioxins/furans.  In this case, a performance test must be conducted during the third year and no more than 37 months after the previous performance test for the pollutant.  The results of the annual stack tests must be submitted using an EPA web-based electronic reporting tool (ERT) within 60 days after conducting the performance tests.

CISWI Yellow SmokestackEPA is proposing several revisions to the monitoring requirements in order to provide facilities with more flexibility and lower compliance costs.  EPA is proposing to allow the optional use of a CO CEMS in lieu of requiring all new CISWI units to install a CO CEMS, as required in the March 21, 2011 CISWI Rules.  Additionally, ERUs with design heat input capacities greater than 250 MMBtu/hr are no longer required to continuously monitor particulate matter (PM) using a PM CEMS.  The proposed amendments to the rule require these larger ERUs to instead use a PM CPMS while still allowing facilities the option to use a PM CEMS to demonstrate compliance.  A variety of PM monitoring systems such as bag leak detectors, ESP secondary power, and PM scrubber pressure could be considered as PM CPMS.  This will provide industry with additional compliance alternatives for PM monitoring.

Path Forward

In parallel with this action, EPA is also proposing revisions to the NHSM definition.  This definition is important because it clarifies how to determine whether a unit is regulated by the CISWI rules.  Facilities should closely examine the implications of these revisions, as outlined in the related article herein for additional details.  The proposed amendments to the CISWI Rules enable easier compliance demonstration by providing added flexibility with regard to CO CEMS and PM CEMS requirements.  Furthermore, the emission standards have been relaxed for many ERUs and Kilns.  Finally, clarifications to the regulatory text will aid facilities in applicability determinations.

EPA’s deadline for public comments on the proposed amendments to the 2011 CISWI Rules and on the reconsideration topics was February 21, 2012.  They were seeking comments on areas such as the following:

  • Should EPA consider further subcategorization of ERUs for HCl and Hg emission limits?
  • Which pollutants warrant production-based limits (lb/ton clinker) in place of, or in addition to, concentration limits (ppmv) for waste-burning kilns?
  • Is there sufficient clarity for fuel switching provisions in the rule; should the rule include further clarification on the timeline and regulatory requirements of a fuel switch; and/or should EPA consider an alternative time period for switching frequency (e.g., 12 months)?
  • Do the proposed revisions to the final rule CO monitoring requirements provide sufficient flexibility in terms of compliance demonstration?
  • Are there any suggested approaches, along with supporting data, for incorporation of fuel variability in emission limit(s)?
  • Does the retention of the “contained gaseous material” definition help clarify EPA’s position with regard to contained gas?
  • Should EPA specify monitoring provisions for dry sorbent injection for acid gas control?  Are there any additional types of control devices that EPA should identify monitoring parameters for in this rule? Are there any other control devices that should be specifically listed in the final rule?

As noted, there are still several issues that need to be resolved by EPA.  Considering the January 9, 2012 vacatur on the stay of the CISWI rules, facilities should remain abreast of updates from the courts and EPA on the appropriate path forward for compliance under the March 21, 2011 final rules as well as the status of the proposed rules under the reconsideration process.

1 Federal Register, Volume 76, Number 247, page 80452
2 Definition of a CISWI unit - 40 CFR 60.2260
3 Letter from Administrator Lisa P Jackson, U.S. EPA, to Senator Wyden, January 18, 2011.
4 It appears that the definition of a new incineration unit listed in 40 CFR 60.2015(a)(1) is incorrect.  This section states that a new incineration unit is “a CISWI unit that commenced construction after [DATE OF 60 DAYS AFTER PUBLICATION OF THE FINAL RULE IN THE FEDERAL REGISTER]”.  However, based on the June 4, 2010 construction date listed in Sections 60.2030, 60.2105, and in the emission limit tables, it is assumed that a CISWI unit constructed after June 4, 2010 is considered a new unit.
5 Air curtain incinerators must obtain a Title V permit, even though they are exempt from the requirements of the CISWI rules.
6 EPA is also proposing two minor revisions to the limits for new incinerators: increases to the limits for Hg and dioxins/furans, total.
7 U.S. EPA. Fact Sheet for Proposed Amendments to the New Source Performance Standards and Emission Guidelines For Commercial and Industrial Solid Waste Incineration Unit.