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On June 4, 2010, the U.S. EPA proposed updates to the Standards of Performance for New Stationary Sources (NSPS) for Commercial and Industrial Solid Waste Incineration (CISWI) Units (NSPS Subpart CCCC) and Emission Guidelines (EG) for Existing CISWI Units (EG Subpart DDDD), collectively referred to as the "CISWI Rules."  In order to describe the proposed updates to the CISWI Rules, it is necessary to review the timeline of important EPA and court decisions surrounding the CISWI Rules.

EPA adopted NSPS and EG for CISWI units on December 1, 2000 (2000 CISWI Rules).  In 2001, the United States Court of Appeals for the DC Circuit (DC Circuit) granted EPA's voluntary remand, without vacatur, of the definition of "commercial and industrial waste" and "CISWI unit."  As such, the definitions included in the 2000 CISWI Rules remain in effect until EPA revises the definitions.  In 2005, EPA proposed and finalized the CISWI definitions, which revised the definition of solid waste, commercial and industrial waste, and CISWI unit (2005 definitions rule); each definition is provided in both the NSPS Subpart CCCC and the EG Subpart DDDD.  In 2007, the DC Circuit vacated and remanded the 2005 definitions rule.  As such, the current regulatory action includes EPA's response to the 2001 voluntary remand of the definitions of "commercial and industrial waste" and "CISWI unit," and EPA's response to the remand and vacatur of the 2005 definitions rule.

Proposed updates to the 2000 CISWI Rules include the following:

  • A CISWI unit will now be required to be in compliance with emission standards at all times, including periods of startup, shutdown, and malfunction (SSM)
  • Additional CISWI units will be covered by the proposed rule as the list of exemptions will be reduced and energy recovery units are not specifically excluded
  • There will be five subcategories of CISWI units while the 2000 CISWI Rules included only a single incinerator category
  • Changes to testing, monitoring, reporting and electronic data submittal requirements
  • All emission limits will be revised (if necessary) as required by the Clean Air Act (CAA) Section 129, which stipulates a five year technology review by EPA
  • The date for determining if a CISWI unit is new or existing will be updated based on the June 4, 2010 publication date of the proposed rule and the final CISWI rule publication date
NSPS versus EG

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 rule or upon initial startup, whichever is later.  An existing CISWI unit is required to 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.

Overview of the 2000 CISWI Rules

The 2000 CISWI Rules provide emission standards for commercial or industrial combustion units that combust commercial or industrial waste.  Note that the 2000 CISWI Rules specifically exclude units that recover energy from the combustion of solid waste, which is defined specifically in each Subpart.  A new incineration unit is one constructed after November 30, 1999, or reconstructed or modified on or after June 1, 2001.  A new incineration unit is subject to NSPS Subpart CCCC.  An existing incineration unit commenced construction on or before November 30, 1999, and is subject to either the State Plan approved by EPA, or if a State Plan has not been approved by EPA, the unit would be subject to the Federal Plan described in EG Subpart DDDD.

There are 15 exemptions listed in the 2000 CISWI Rules:  pathological waste incineration units; agricultural waste incineration units; municipal waste combustion units; medicalwaste incineration units; small power production facilities; cogeneration facilities; hazardous waste combustion units; materials recovery units; air curtain incinerators; cyclonic barrel burners; rack, part, and drum reclamation units; cement kilns; sewage sludge incinerators; chemical recovery units; and laboratory analysis units.  Please note the scope of the exemptions is significantly changed in the proposed rule, as discussed below.

The emission standards provided in the 2000 CISWI Rules apply to only one category of CISWI units, labeled "Incinerators."  The pollutants regulated include cadmium, carbon monoxide (CO), dioxins/furans (toxic equivalency basis [TEQ]), hydrogen chloride (HCl), lead, mercury, opacity, oxides of nitrogen (NO), particulate matter (PM), and sulfur dioxide (SO).

Proposed Revisions to the 2000 CISWI Rules

The following sections provide a general overview of the proposed changes to the 2000 CISWI rules.

CISWI Unit and Solid Waste Definitions
The 2000 CISWI rules included a definition of solid waste within NSPS Subpart CCCC and EG Subpart DDDD that differed from the definition of solid waste under the Resource Conservation and Recovery Act (RCRA).  Because the D.C. Circuit ruled that CAA Section 129 requires that the term "solid waste" have the same meaning established by EPA under RCRA, EPA must incorporate the RCRA solid waste definition in the proposed CISWI Rules.  As such, EPA is proposing the following definition for a CISWI unit: "any distinct operating unit of any commercial or industrial facility that combusts any solid waste as that term is defined in 40 CFR Part 241 [RCRA]... ."  Although the proposed change in definition and other rule changes broaden the scope of the CIWSI rules, subjecting more types of units to the CISWI rules, there are still some categories excluded from the CISWI rules, as discussed below.

In a parallel regulatory action, EPA has amended the definition of solid waste provided under 40 CFR Section 241 to add an exclusion for "non-hazardous secondary wastes" that would otherwise qualify as solid waste under 40 CFR Section 241.  Please refer to the article titled "New Solid Waste Definition Proposed" on page 10 of this EQ publication for additional details.

Applicability and Exemptions

Under the proposed rule changes, a CISWI unit will be considered a new unit, and therefore, subject to NSPS Subpart CCCC if:

  1. Construction commences after June 4,  2010, or
  2. Reconstruction or modification commences six months after the final rules are promulgated by EPA, which is expected in December 2010.


EPA projects that there will not be any new units constructed over the next three years as it will be too expensive to add controls that will allow the new unit to comply with the proposed emission limits.

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 commences no later than six months after the final rules are promulgated by EPA, which is expected in December 2010. 


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 proposed CISWI Rules 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 below, 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 final rules are promulgated by EPA, whichever is earlier.

The following exemptions are proposed to be removed from the 2000 CISWI Rules:  agricultural waste incineration units; cyclonic barrel burners; rack, part, and drum reclamation units; cement kilns; chemical recovery units; and laboratory analysis units.  All other exemptions will remain in the updated CISWI rules.  The revised exemption list will include the following: 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; and sewage sludge incinerators.

CISWI Unit Subcategories and Emission Limits
The proposed CISWI Rules will include five subcategories of CISWI units, as follows:

  1. Incinerators
  2. Energy Recovery Units
  3. Waste Burning Kilns
  4. Burn-off Ovens
  5. Small, Remote Incinerators


Each subcategory will have different emission limits.  EPA set emission limits using the maximum achievable control technology (MACT) procedures as required by Section 129 for new and existing sources.  Therefore, the emission limits for new CISWI units reflect the best limits that are achievable in practice by the best controlled similar unit, and the emission limits for existing CISWI units reflect the emission limits achieved by the top twelve percent of comparable CISWI units.  EPA performed a MACT analysis on each of the five subcategories.

It was necessary for EPA to determine if the unit combusted solid waste in order to determine if a unit met the definition of a CISWI unit.  Therefore, EPA was forced to use the definition of solid waste, including the proposed revisions regarding non-hazardous secondary wastes, to determine if a unit would be subject to the CISWI Rules.  If EPA changes the proposed exclusions for non-hazardous secondary wastes, the entire MACT analysis will need to be revised.  Note that energy recovery units and waste burning kilns are the only subcategories that could potentially use the non-hazardous secondary waste exclusion currently under review.

As an example, if a boiler combusted a solid waste that qualified for the non-hazardous secondary waste exclusion, that boiler would not have been included in the MACT analysis for Energy Recovery Units.  If EPA finalizes the RCRA definition of solid waste and removes the non hazardous secondary waste exclusions, the boiler would be considered a CISWI unit because the unit would combust a solid waste.  As such, the boiler will have to be considered in the MACT analysis, which may impact what was set as the MACT floors for both new and existing CISWI units.

Tables 1 and 2 include the original 2000 CISWI Rule emission limits and the proposed emission limits for existing and new CISWI units, respectively.  Please note that the proposed rule eliminates the exemption from emission limits during period of SSM: therefore, the proposed emission limits will apply at all times.

Control Devices

In order to comply with the emissions standards provided in Tables 1 and 2, sources will most likely have to install one or more control devices on the CISWI unit (if the CISWI unit owner continues to combust solid waste instead of using an alternative disposal option, such as a landfill).  The proposed CISWI Rules provide operating parameters for the following control technologies: wet scrubber, activated carbon injection, selective noncatalytic reduction (SNCR), and electrostatic precipitator (ESP).  Should a facility determine that use of an alternate air pollution control device is necessary, or that emissions will be limited in another manner, the facility must submit a petition to EPA requesting approval of the proposed operating parameters that will be monitored to demonstrate compliance with the emission limits.  EPA must approve the petition prior to any performance testing.

The following operating parameters will need to be monitored using a continuous parameter monitoring system (CPMS), depending on what type of control device is used to reduce emissions:

  1. Wet scrubbers — charge rate, pressure drop or current, scrubber liquid flow rate, scrubber liquid pH
  2. Activated carbon injection — mercury sorbent injection rate
  3. Fabric filters — bag leak detection system
  4. SNCR — charge rate, secondary chamber temperature (if applicable), reagent flow rate
  5. ESP — voltage and current


One significant addition in the proposed rules is a requirement to 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.  Proposed testing and monitoring requirements are identified below in Table 3.

What to Expect?

EPA is accepting public comments on the proposed CISWI rules through August 3, 2010.  EPA is specifically interested in comments on the following key topics (this list is not comprehensive):

  • Should existing units other than energy recovery units be required to install a CO and PM CEMS?
  • Was EPA's approach for establishing the dioxin, furan, and opacity limits appropriate?
  • Is EPA justified in reducing the sources that are proposed to be exempt from the CISWI rule?
  • Is it appropriate to use previously conducted performance tests?
  • Is it practical to require energy recovery units with a capacity of 100 MMBtu/hr to install a PM CEMS?

The final CISWI rules are expected to be published by December 2010.