Standards of Performance for New Stationary Sources and Emission Guidelines for Existing Sources: Commercial and Industrial Solid Waste Incineration Units, 55568-55581 [05-18825]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 70, Number 183 (Thursday, September 22, 2005)]
[Rules and Regulations]
[Pages 55568-55581]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-18825]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 60

[OAR-2003-0119; FRL-7971-9]
RIN 2060-AN31


Standards of Performance for New Stationary Sources and Emission 
Guidelines for Existing Sources: Commercial and Industrial Solid Waste 
Incineration Units

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule; amendments.

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SUMMARY: The EPA has completed its reconsideration of certain 
regulatory definitions that determine the type of sources subject to 
EPA's new source performance standards (NSPS) and emission guidelines 
(EG) for commercial and industrial solid waste incineration (CISWI) 
units under section 129 of the Clean Air Act (CAA). With this action, 
EPA is promulgating revised definitions for the terms ``solid waste,'' 
``commercial or industrial waste,'' and ``commercial and industrial 
solid waste incineration unit.'' The final CISWI definitions of these 
terms promulgated today are consistent with EPA's February 2004 
reconsideration proposal in that EPA will continue to identify CISWI 
units based on whether such units combust waste without energy 
recovery. However, the revised definitions promulgated today do not 
include certain regulatory language proposed in February 2004 to 
include units with only waste heat recovery in the CISWI source 
category. In a subsequent rulemaking action, EPA intends to propose 
additional regulatory language to address units with only waste heat 
recovery and assess the impacts of the inclusion of these units in the 
CISWI source category. As a result of our action today on the CISWI 
definitions, it is not necessary to make any corresponding revisions to 
the National Emissions Standards for Hazardous Air Pollutants (NESHAP) 
for Industrial, Commercial, and Institutional Boilers and Process 
Heaters.

DATES: The final rule is effective September 22, 2005.

ADDRESSES: Docket: EPA has established a docket for this action under 
Docket ID No. OAR-2003-0119. All documents in the docket are listed in 
the EDOCKET index at https://www.epa.gov/edocket. Although listed in the 
index, some information is not publicly available, i.e., CBI or other 
information whose disclosure is restricted by statute. Certain other 
material, such as copyrighted material, is not placed on the Internet 
and will be publicly available only in hard copy form. Publicly 
available docket materials are available either electronically in 
EDOCKET or in hard copy at the EPA Docket Center (EPA/DC), EPA West 
Building, Room B102, 1301 Constitution Ave., NW., Washington, DC. The 
Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through 
Friday, excluding legal holidays. The telephone number for the Public 
Reading Room is (202) 566-1744, and the telephone number for the EPA 
Docket Center is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: Mr. Brian Shrager, Combustion Group, 
Emission Standards Division (C439-01), U.S. EPA, Research Triangle 
Park, North Carolina 27711; telephone number: (919) 541-7689; e-mail 
address: shrager.brian@epa.gov.

SUPPLEMENTARY INFORMATION:
    Judicial Review. Under section 307(b)(1) of the CAA, judicial 
review of the final rule is available only by filing a petition for 
review in the U.S. Court of Appeals for the District of Columbia by 
November 21, 2005. Under section 307(d)(7)(B) of the CAA, only an

[[Page 55569]]

objection to the final rule that was raised with reasonable specificity 
during the period for public comment can be raised during judicial 
review. Moreover, under section 307(b)(2) of the CAA, the requirements 
established by today's final action may not be challenged separately in 
any civil or criminal proceedings brought by EPA to enforce these 
requirements.
    Organization of This Document. The following outline is provided to 
aid in locating information in this preamble.

I. General Information
    A. Does this action apply to me?
II. Summary of Final Action
III. Background Information
    A. Statutory Background
    B. Regulatory Background
    C. Significance of the Definitions
IV. Final Definitions for the CISWI Rules
V. Response to Public Comments and Significant Changes
    A. General Comments on Definitions
    B. Comments on the Definition of CISWI Unit
    C. Comments on the Definition of Commercial or Industrial Waste
    D. Comments on the Definition of Solid Waste
    E. Comments on the Rulemaking Process
VI. Relationship to NESHAP for Boilers and Process Heaters
VII. Impacts of the Final Rules
VIII. Future Actions on the Final CISWI Rules
IX. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination with 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children from 
Environmental Health and Safety Risks
    H. Executive Order 13211: Actions that Significantly Affect 
Energy Supply, Distribution or Use
    I. National Technology Transfer Advancement Act
    J. Congressional Review Act

I. General Information

A. Does This Action Apply to Me?

    Regulated Entities. The CISWI rules potentially affect the 
following categories of sources:

------------------------------------------------------------------------
                                                           Examples of
                                                           potentially
           Category             NAICS code    SIC code      regulated
                                                             entities
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Any industry using a solid             325           28  Manufacturers
 waste incinerator as defined                             of chemicals
 in the regulations.                                      and allied
                                                          products.
                                       335           36  Manufacturers
                                                          of electronic
                                                          equipment.
                                       421           50  Manufacturers
                                                          of wholesale
                                                          trade, durable
                                                          goods.
                                  321, 337       24, 25  Manufacturers
                                                          of lumber and
                                                          wood
                                                          furniture.
------------------------------------------------------------------------

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be regulated by this 
action. This table lists examples of the types of entities that could 
be affected by this action. Other types of entities not listed in this 
table could also be affected. To determine whether your facility, 
company, or business organization is regulated by this action, you 
should examine the final definitions of ``solid waste,'' ``commercial 
or industrial waste,'' and ``commercial and industrial solid waste 
incineration unit'' in this action and the applicability criteria in 40 
CFR 60.2010 through 60.2025, subpart CCCC, and 40 CFR 60.2505 and 
60.2550 through 60.2558, subpart DDDD.
    Docket. The docket number for this action is OAR-2003-0119.
    Worldwide Web (WWW). In addition to being available in the docket, 
an electronic copy of the notice of final rules is available on the WWW 
through the Technology Transfer Network Web site (TTN Web). Following 
signature, EPA will post a copy of the notice of final rules on the 
TTN's policy and guidance page for newly proposed or promulgated rules 
at https://www.epa.gov/ttn. The TTN provides information and technology 
exchange in various areas of air pollution control.

II. Summary of Final Action

    By this action, EPA concludes the reconsideration process on the 
December 2000 final CISWI rules that it initiated in February 2004, in 
response to a petition for reconsideration submitted pursuant to 
section 307(d)(7)(B) of the CAA. Specifically, the EPA has concluded 
its reconsideration of several definitions that determine which types 
of sources are subject to the NSPS and EG for CISWI units under section 
129 of the CAA.
    EPA promulgated the definitions in the final rules for CISWI units 
on December 1, 2000. Subsequent to promulgation of the final CISWI 
rules, the Agency granted a petition for reconsideration related to the 
definitions of ``commercial and industrial waste'' and ``commercial and 
industrial solid waste incineration unit'' in the CISWI final rules. 
EPA solicited public comments on revised definitions for these terms 
and the definition of ``solid waste'' in a notice published in the 
Federal Register on February 17, 2004. (See 69 FR 7390.) In that 
notice, we requested comments on the approach we used in the December 
2000 final rules to identify CISWI units based on whether the unit was 
combusting solid waste without energy recovery. We also proposed to 
include units with only waste heat recovery in the CISWI source 
category to fill a gap between our CISWI rules and our NESHAP for 
Industrial, Commercial, and Institutional Boilers and Process Heaters 
promulgated under CAA section 112.
    In addition, after promulgation of the final CISWI rules in 2000, 
EPA accepted a voluntary remand, without vacature, in response to a 
petition for review challenging the rules. Because the final rules were 
not vacated, the requirements of the final CISWI rules remain in effect 
during the remand. In a future rulemaking action on the remand, we will 
reconsider the emissions limitations for CISWI units in accordance with 
guidelines set forth in a related court decision pertaining to 
hazardous waste combustors which was issued after we promulgated the 
final CISWI rules. However, before we may complete the rulemaking 
action on remand, it is necessary to resolve the issues raised in the 
petition for reconsideration that potentially affect the scope of the 
CISWI source category. This is because EPA must consider the emissions 
of the best performing sources in the source category to determine the 
applicable emissions limitations. Thus, we are announcing today our 
final decision after reconsidering the definitions that determine the 
scope of the CISWI source category so that we may focus on the relevant 
sources in our rulemaking action on the remand. Today's action amends 
the final rules to incorporate new definitions of ``solid waste,'' 
``commercial or industrial waste,'' and ``commercial and industrial 
solid waste incineration unit.'' In the discussion below, we set forth 
and explain the language in the new definitions.
    The definitions we are promulgating today are nearly the same as 
those

[[Page 55570]]

proposed on February 17, 2004. (See 69 FR 7396.) However, in response 
to comments received, we clarified the proposed definition of 
``commercial or industrial waste'' and made editorial changes to other 
definitions to reduce repetition among the definitions and to better 
express our intent.
    In addition, we removed the term ``waste heat recovery'' from the 
proposed definition of ``commercial or industrial waste'' and are not 
adopting a final definition of ``waste heat recovery'' at this time. We 
intend to propose additional language to address units with only waste 
heat recovery and to assess the impacts of including such sources in 
the CISWI source category during completion of our rulemaking action in 
response to the voluntary remand. At that time, EPA will also address 
several other issues relevant to the remand, such as the emissions 
limitations for the CISWI source category.
    The revisions to the definitions adopted today are not intended to 
change the existing scope \1\ of the CISWI source category. After 
further review on reconsideration, EPA continues to believe that the 
key consideration in determining whether a unit is burning commercial 
or industrial waste is the primary function of the combustion unit and 
that the primary indicator of function is whether or not a unit is 
designed and operated for energy recovery. We define energy recovery as 
the recovery of heat (thermal energy) for a useful purpose. Thus, we 
are not amending the definition of ``energy recovery'' that we 
promulgated in the December 2000 final CISWI rules.
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    \1\ The inclusion of waste heat recovery sources would change 
the scope of the CISWI source category if we take final action to 
include such sources in the CISWI source category in our response to 
the voluntary remand.
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    Today's action also addresses a related question of whether EPA 
should amend regulations that determine the scope of the NESHAP for the 
Industrial, Commercial, and Institutional Boilers and Process Heaters 
source category (boilers NESHAP). Those regulations (40 CFR part 63, 
subpart DDDDD) were promulgated under CAA section 112. (See 69 FR 
55218, September 13, 2004.) We determined that conforming amendments to 
the boilers NESHAP are not necessary because the definitions of 
``boilers'' and ``process'' heaters in that rule are consistent with 
the CISWI definitions we are announcing today.

III. Background Information

A. Statutory Background

    Section 129 of the CAA, entitled ``Solid Waste Combustion,'' 
requires EPA to promulgate emissions standards and other requirements 
for ``each category of solid waste incineration units'' (42 U.S.C. 
7429(a)(1)). Section 129(a)(1) of the CAA identifies five categories of 
solid waste incineration units:
    (1) Units with a capacity of greater than 250 tons per day 
combusting municipal waste;
    (2) Units with a capacity equal to or less than 250 tons per day 
combusting municipal waste;
    (3) Units combusting hospital, medical and infectious waste;
    (4) Units combusting commercial or industrial waste; and
    (5) Unspecified ``other categories of solid waste incineration 
units.''
    For each category of incineration unit identified under CAA section 
129, EPA must establish numerical emission limits for at least nine 
specified pollutants (particulate matter (PM), sulfur dioxide 
(SO2), hydrogen chloride (HCl), oxides of nitrogen 
(NOX), carbon monoxide (CO), lead (Pb), cadmium (Cd), 
mercury (Hg), and dioxins and dibenzofurans) and for opacity as 
appropriate. Section 129 provides EPA with the discretion to establish 
emissions limitations for other pollutants as well.
    Section 129 of the CAA directs EPA to set maximum achievable 
control technology (MACT) type standards for incinerators. EPA's 
standards under section 129 must ``reflect the maximum degree of 
reduction in emissions of air pollutants listed under section (a)(4) 
(identified above) that the Administrator, taking into consideration 
the cost of achieving such emission reduction, and any non-air quality 
health and environmental impacts and energy requirements, determines is 
achievable for new or existing units in each category.'' (See CAA 
section 129(a)(2).) However, the standards for new units must not be 
``less stringent than the emissions control that is achieved in 
practice by the best controlled similar unit,'' and the standards for 
existing sources must not be ``less stringent than the average 
emissions limitation achieved by the best performing 12 percent of 
units in the category.'' (See CAA section 129(a)(2).)
    In addition, the statute provides some guidance on which units EPA 
should and should not regulate under CAA section 129. However, the 
statute does not define ``commercial or industrial waste.'' Section 
129(g)(1) of the CAA defines the term ``solid waste incineration unit'' 
as a unit ``which combusts any solid waste material from commercial or 
industrial establishments or the general public.'' Section 129(g)(1) 
also identifies several types of units that are not solid waste 
incineration units, including units required to have a permit under 
section 3005 of the Solid Waste Disposal Act (SWDA); materials recovery 
facilities; certain qualifying small power production facilities or 
qualifying cogeneration facilities which burn homogeneous waste; and 
certain air curtain incinerators that meet opacity limitations 
established by EPA.
    Furthermore, CAA section 129(g)(6) states that the term ``solid 
waste * * * shall have the meanings established by the Administrator 
pursuant to the Solid Waste Disposal Act.'' Finally, CAA section 129(h) 
states that ``no solid waste incineration unit subject to performance 
standards under this section and section 111 shall be subject to 
standards under section 112(d) of this Act.''

B. Regulatory Background

    One important part of EPA's rulemaking process is determining what 
universe of sources will be subject to regulation. With regard to CISWI 
units, the statutory provisions of CAA sections 129(a), (g) and (h) 
collectively provide that EPA must determine, as a part of the 
regulatory process, which combustion units should be subject to 
regulation under section 129. Section 129 does not resolve this 
question, but it does provide some important guiding principles. For 
example, section 129(g)(1) provides that a solid waste incineration 
unit does not include incinerators or other units required to have a 
permit under section 3005 of the SWDA, which includes any units burning 
hazardous solid wastes. This statutory language effectively limits the 
scope of EPA's authority under section 129 to the regulation of solid 
waste incineration units that burn nonhazardous solid waste. Similarly, 
the language of section 129(h) makes clear the Congressional intent for 
EPA to regulate nonhazardous combustion sources under either section 
129 or section 112, but not both. Thus, for the CISWI source category, 
in particular, EPA must determine which sources are commercial and 
industrial solid waste incineration units under section 129, and which 
combustion units are subject to section 112, such as boilers and 
process heaters.
    The EPA proposed regulations for CISWI units on November 30, 1999. 
(See 64 FR 67092.) The proposal included

[[Page 55571]]

emissions limitations and a detailed definition of ``solid waste'' that 
was intended to distinguish between nonhazardous solid wastes and other 
materials (e.g., hazardous solid waste and fuel) burned in combustion 
units at commercial or industrial facilities. The definition served to 
identify those units that would be considered commercial and industrial 
nonhazardous solid waste incineration units, and, therefore, subject to 
the proposed regulations. In addition, consistent with CAA section 
129(h), these definitions also helped to identify those units which 
would not be subject to emission standards under CAA section 112.
    After receiving public comment, EPA determined that the 1999 
proposed definition of ``solid waste'' was unworkable for purposes of 
identifying CISWI units. Instead of adopting the proposed definition of 
``solid waste,'' EPA adopted a general definition of ``solid waste'' 
that closely mirrored the definition of solid waste found at section 
6903(27) of the SWDA and in several places in EPA's regulations under 
that statute. (See 65 FR 75338, December 1, 2000.) EPA also adopted 
more specific definitions of ``commercial and industrial waste'' and 
``commercial and industrial solid waste incineration unit,'' to 
identify more precisely those units at commercial and industrial 
facilities covered by the final CISWI rules.
    Under the December 2000 final CISWI rules, a material burned at a 
commercial or industrial facility in a combustion unit without energy 
recovery is a commercial or industrial waste, and the unit is subject 
to the CISWI rules. However, a material burned at a commercial or 
industrial facility in a combustion unit with energy recovery is not 
considered a commercial and industrial waste, nor is the combustion 
unit considered a commercial and industrial solid waste incineration 
unit for purposes of the CISWI rules.\2\
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    \2\ In addition, EPA adopted a number of specific exemptions and 
additional definitions in the final CISWI rules, to ensure that the 
emissions limitations did not apply to units that should not be 
considered commercial and industrial solid waste incineration units. 
These exemptions and definitions served to identify and exempt: (1) 
Pathological solid waste incineration units; (2) agricultural solid 
waste incineration units: (3) municipal solid waste incineration 
units; (4) hospital, medical and infectious solid waste incineration 
units; (5) qualifying small power production facilities; (6) 
qualifying cogeneration facilities; (7) hazardous solid waste 
incineration units; (8) material recovery units; (9) certain air 
curtain incinerators; (10) cyclonic barrel burners; (11) rack, part, 
and drum reclamation units; (12) cement kilns; (13) sewage sludge 
incinerators; (14) chemical recovery units; and (15) laboratory 
analysis units.
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    After promulgation of the final CISWI rules, EPA received a 
petition for reconsideration of the final rules. The petition argued 
that the final rules were procedurally defective because EPA had failed 
to provide adequate notice and an opportunity to comment on the 
definitions adopted in the final rulemaking. Additionally, an 
environmental organization filed a petition for review in the U.S. 
Court of Appeals for the D.C. Circuit. Furthermore, after promulgation 
of the final CISWI rules, the D.C. Circuit issued its decision in 
Cement Kiln Recycling Coalition v. EPA, 255 F.3d 855 (D.C. Cir. 2001). 
In this decision, the Court rejected certain common elements of EPA's 
MACT methodology. As a result, EPA requested a voluntary remand of the 
final CISWI rules, in order to address concerns related to the issues 
that the Court had raised in the Cement Kiln decision.
    The EPA granted the petition for reconsideration on the 
definitional issues. On February 17, 2004 (69 FR 7390), EPA initiated 
proceedings on the definitional issues by publishing a notice to 
solicit comments on revisions to the definitions of ``solid waste,'' 
``commercial or industrial waste,'' and ``commercial and industrial 
solid waste incineration unit'' and a new definition of the term 
``waste heat recovery.'' The February 17, 2004 notice proposed the 
following definitions:

    Solid waste means any garbage, refuse, sludge from a waste 
treatment plant, water supply treatment plant, or air pollution 
control facility and other discarded material, including solid, 
liquid, semisolid, or contained gaseous material resulting from 
industrial, commercial, mining, agricultural operations, and from 
community activities, but does not include solid or dissolved 
material in domestic sewage, or solid or dissolved materials in 
irrigation return flows or industrial discharges which are point 
sources subject to permits under section 402 of the Federal Water 
Pollution Control Act, as amended (33 U.S.C. 1342), or source, 
special nuclear, or byproduct material as defined by the Atomic 
Energy Act of 1954, as amended (42 U.S.C. 2014).
    Commercial or industrial waste means solid waste (as defined in 
this subpart) combusted for reasons that do not include the recovery 
of heat for a useful purpose, or combusted without heat recovery or 
with only waste heat recovery (i.e., no heat recovery in the 
combustion firebox), in an enclosed unit using controlled flame 
combustion that is a distinct operating unit of any commercial or 
industrial facility (including field-erected, modular, and custom 
built incineration units operating with starved or excess air); or 
solid waste combusted in an air curtain incinerator that is a 
distinct operating unit of any commercial or industrial facility.
    Commercial and industrial solid waste incineration (CISWI) unit 
means any combustion unit that combusts commercial or industrial 
waste (as defined in this subpart), that is a distinct operating 
unit of any commercial or industrial facility (including field-
erected, modular, and custom built incineration units operating with 
starved or excess air), and any air curtain incinerator that is a 
distinct operating unit of any commercial or industrial facility 
that does not comply with the opacity limits under this subpart 
applicable to air curtain incinerators burning commercial or 
industrial waste. While not all CISWI units will include all of the 
following components, a CISWI unit includes, but is not limited to, 
the commercial or industrial solid waste feed system, grate system, 
flue gas system, waste heat recovery equipment, if any, and bottom 
ash system. The CISWI unit does not include air pollution control 
equipment or the stack. The CISWI unit boundary starts at the 
commercial or industrial waste hopper (if applicable) and extends 
through two areas: (1) The combustion unit flue gas system, which 
ends immediately after the last combustion chamber or after the 
waste heat recovery equipment, if any; and (2) The combustion unit 
bottom ash system, which ends at the truck loading station or 
similar equipment that transfers the ash to final disposal. The 
CISWI unit includes all ash handling systems connected to the bottom 
ash handling system. A CISWI unit does not include any of the 
fifteen types of units described in section 60.2555 of this subpart, 
nor does it include any combustion turbine or reciprocating internal 
combustion engine.
    Waste heat recovery means the process of recovering heat from 
the combustion flue gases by convective heat transfer only.

    These definitions were similar to the definitions in the December 
1, 2000 final CISWI rules, except that we proposed that materials 
combusted at commercial or industrial facilities in units with only 
waste heat recovery would be considered commercial or industrial waste 
and that such units would become subject to the CISWI rules. This 
proposed change addressed an unintended regulatory gap where units with 
only waste heat recovery were not covered by CAA section 112 boilers 
NESHAP or by the CISWI rules. The statutory and regulatory background 
and rationale for the proposed changes to the definitions are fully 
described in the February 17, 2004 notice of proposed rule and 
solicitation of comments. (See 69 FR 7390.)
    The action published today summarizes and responds to public 
comments received in response to the February 17, 2004 notice and 
announces EPA's final decisions on the definitions of ``solid waste,'' 
``commercial or industrial waste,'' and ``commercial and industrial 
solid waste incineration (CISWI) unit'' for the CISWI rules. The 
specific wording of the final definitions

[[Page 55572]]

is printed later in this action. EPA is amending the CISWI rules such 
that the final definitions will take effect immediately. EPA is not 
taking final action today, however, on the February 2004 proposed 
addition of certain regulatory language concerning waste heat recovery 
units. EPA currently intends to propose additional language to amend 
the CISWI rules to cover units with only waste heat recovery when we 
take final action in response to the voluntary remand of the CISWI 
rules.

C. Significance of the Definitions

    The definitions of ``solid waste,'' ``commercial or industrial 
waste,'' and ``commercial and industrial solid waste incineration 
unit'' define the scope of applicability of the final CISWI rules. 
Since any unit regulated under CAA section 129 cannot be subject to any 
rule developed under CAA section 112, these definitions also help to 
clarify the scope of applicability of certain other rules that EPA has 
or will develop for other types of combustion units.
    In this case, combustion units that are not covered by the final 
CISWI rules may be subject to regulation, for example, under the 
boilers NESHAP (40 CFR part 63, subpart DDDDD).\3\ Many of the 
combustion units at commercial or industrial facilities (e.g., boilers 
or steam generating units, process heaters, furnaces, and incinerators) 
burn ``solid'' materials. If the solid materials in question are 
covered by the definition of ``commercial or industrial waste,'' the 
units will be regulated as CISWI units under CAA section 129. 
Conversely, if the materials are not covered by the definition of 
``commercial or industrial waste'' or if these materials are hazardous 
solid waste or solid materials burned for chemical or material 
recovery, the units will be regulated under CAA section 112 or other 
statutory authority.
---------------------------------------------------------------------------

    \3\ Alternatively, such units might be subject to regulation 
under any number of other EPA regulations, including, for example, 
regulations promulgated pursuant to CAA section 112(c)(3) and (k) to 
control emissions from industrial, commercial and institutional 
boilers that are area sources and various other regulations 
developed under section 112 which cover combustion units burning 
solid materials to recover their chemical or other material 
constituents (e.g., black liquor boilers or furnaces at kraft pulp 
mills covered under the national emission standards for hazardous 
air pollutants for Chemical Recovery Combustion Sources at Kraft, 
Soda, Sulfite, and Stand-Alone Semichemical Pulp Mills).
---------------------------------------------------------------------------

    The process of determining the regulatory dividing line between 
different rules is not unique to CISWI. Nor does the identification of 
the scope of one rule necessarily define the scope of another or 
preclude EPA from adjusting the regulatory division in a subsequent 
rule.

IV. Final Definitions for the CISWI Rules

    For purposes of the CISWI rules, we are amending the definitions of 
the terms ``solid waste,'' ``commercial or industrial waste,'' and 
``commercial and industrial solid waste incineration (CISWI) unit'' as 
follows:

    Solid waste means any garbage, refuse, sludge from a waste 
treatment plant, water supply treatment plant, or air pollution 
control facility and other discarded material, including solid, 
liquid, semisolid, or contained gaseous material resulting from 
industrial, commercial, mining, agricultural operations, and from 
community activities, but does not include solid or dissolved 
material in domestic sewage, or solid or dissolved materials in 
irrigation return flows or industrial discharges which are point 
sources subject to permits under section 402 of the Federal Water 
Pollution Control Act, as amended (33 U.S.C. 1342), or source, 
special nuclear, or byproduct material as defined by the Atomic 
Energy Act of 1954, as amended (42 U.S.C. 2014).
    Commercial or industrial waste means solid waste (as defined in 
this subpart) that is combusted at any commercial or industrial 
facility using controlled flame combustion in an enclosed, distinct 
operating unit: (1) Whose design does not provide for energy 
recovery (as defined in this subpart); or (2) operated without 
energy recovery (as defined in this subpart). Commercial or 
industrial waste also means solid waste (as defined in this subpart) 
combusted in an air curtain incinerator that is a distinct operating 
unit of any commercial or industrial facility.
    Commercial and industrial solid waste incineration (CISWI) unit 
means any combustion unit that combusts commercial or industrial 
waste (as defined in this subpart), that is a distinct operating 
unit of any commercial or industrial facility (including field-
erected, modular, and custom built incineration units operating with 
starved or excess air), and any air curtain incinerator that is a 
distinct operating unit of any commercial or industrial facility 
that does not comply with the opacity limits under this subpart 
applicable to air curtain incinerators burning commercial or 
industrial waste. While not all CISWI units will include all of the 
following components, a CISWI unit includes, but is not limited to, 
the commercial or industrial solid waste feed system, grate system, 
flue gas system, waste heat recovery equipment, if any, and bottom 
ash system. The CISWI unit does not include air pollution control 
equipment or the stack. The CISWI unit boundary starts at the 
commercial or industrial waste hopper (if applicable) and extends 
through two areas: (1) The combustion unit flue gas system, which 
ends immediately after the last combustion chamber or after the 
waste heat recovery equipment, if any; and (2) the combustion unit 
bottom ash system, which ends at the truck loading station or 
similar equipment that transfers the ash to final disposal. The 
CISWI unit includes all ash handling systems connected to the bottom 
ash handling system. A CISWI unit does not include any of the 
fifteen types of units described in section 60.2555 of this subpart, 
nor does it include any combustion turbine or reciprocating internal 
combustion engine.

    The EPA will continue to define the term ``energy recovery'' as 
follows:

    Energy recovery means the process of recovering thermal energy 
from combustion for useful purposes such as steam generation or 
process heating.

    The major differences between the definitions we are promulgating 
today for the CISWI rules and those proposed on February 17, 2004 (69 
FR 7396), are that we have removed the language in the proposed 
definition of ``commercial or industrial waste'' that served to include 
units with only waste heat recovery in the CISWI source category, and 
we are not promulgating the definition of ``waste heat recovery'' at 
this time. We are not taking final action today on these changes 
because we have not yet had an opportunity to assess the impacts of 
including units with waste heat recovery in the CISWI rules. An impacts 
assessment is necessary, but is best done when we respond to the CISWI 
remand and can perform comprehensive analyses that address the addition 
of waste heat recovery units, any questions on the applicability of the 
CISWI rules raised by promulgation of the CAA section 129 rules for the 
other solid waste incineration (OSWI) source category, and the remand 
issues regarding determination of the MACT floor and emission limits. 
When we respond to the remand of the CISWI rules, we currently plan to 
propose additional regulatory language to address units with only waste 
heat recovery and to provide opportunity for additional comment on the 
inclusion of these units in the CISWI source category.
    Otherwise, as explained further below, we made editorial changes to 
the definition of ``commercial or industrial waste'' and other 
definitions to reduce repetition among the definitions and better 
express our intent. For example, we use the term ``energy recovery'' in 
the final definition of ``commercial or industrial waste'' to 
incorporate our existing definition rather than repeating the words 
``recovery of heat for a useful purpose.''

V. Response to Public Comments and Significant Changes

    Twelve public comment letters were received from a wide variety of 
sources, consisting mainly of government agencies, environmental 
organizations, industry and utility associations, and owner/operators 
of incinerators and

[[Page 55573]]

other types of facilities. The most significant comments are summarized 
and addressed below. Other significant comments are summarized and 
addressed in a comment and response document contained in the docket.

A. General Comments on Definitions

    Comment: One commenter stated that EPA's attempts to fabricate 
ambiguity in CAA section 129 are without merit. The commenter stated 
that, regardless of whether EPA has discretion to draw the line between 
different types of solid waste combustion units, the agency does not 
have the discretion to exempt any such units from regulation under 
section 129 (except for those expressly enumerated in section 
129(g)(1)). The commenter added that, contrary to EPA's claim, the 
critical question is not whether a unit ``is designed and operated to 
recover heat for a useful purpose,'' but, rather, ``does the unit 
combust solid waste?'' Finally, the commenter added that, read as a 
whole, section 129 requires that the CISWI rules must apply to all 
combustion units that burn waste from commercial and industrial 
facilities. The commenter contended that EPA's narrow definitions of 
``commercial or industrial waste'' and ``commercial and industrial 
solid waste incineration unit'' unlawfully exempt the majority of CISWI 
units from regulation under section 129. The commenter also pointed out 
that most CISWI units fall below the major source threshold established 
in CAA section 112(a). The commenter viewed EPA's definitions in the 
CISWI rules as an attempt to regulate many sources under section 112 
instead of regulating all sources under section 129. Section 112 
requires emissions standards based on generally available control 
technology (GACT) for non-major sources.
    Response: EPA disagrees with the commenter. Contrary to the 
commenter's assertion, CAA section 129 is ambiguous because it does not 
contain definitions of certain terms. The EPA has reasonably 
interpreted section 129 in establishing the regulatory definitions 
described in this action. The statutory provisions of sections 129(a), 
(g), and (h) of the CAA collectively call for EPA to determine, as part 
of the regulatory process, which combustion units should be subject to 
regulation under section 129. Section 129 of the CAA directs EPA to 
promulgate standards under section 111 applicable to ``solid waste 
incineration units combusting commercial or industrial waste''. (See 42 
U.S.C. 7429(a)(1)(D).) However, section 129 does not define commercial 
or industrial waste. Inherent in EPA's implementation of this statutory 
provision is the discretion to reasonably define what constitutes this 
undefined type of solid waste. Furthermore, CAA section 129(h) provides 
that nonhazardous combustion sources shall not be regulated under both 
section 129 and section 112. Thus, for the CISWI rules, EPA must 
determine which types of sources are included in the CISWI source 
category.
    The distinction between CISWI units and non-CISWI combustion units 
is not readily apparent. For example, there is general agreement that 
burning coal in a coal-fired boiler is not commercial or industrial 
waste, because coal is commonly thought of as a fuel. However, there 
are many other materials that are burned in commercial and industrial 
boilers for energy recovery. Such materials include wood, other 
biomass, bagasse burned in boilers at sugar plants to produce the heat 
needed to refine sugar from sugar cane, and many other materials 
generated as part of commercial or manufacturing activities. When these 
materials are burned in a boiler to recover heat for a useful purpose, 
it is reasonable to consider these materials, like coal, to be a fuel 
and distinct from commercial and industrial solid waste. Combustion of 
such materials, when burned in a boiler that recovers energy for a 
useful purpose, is not considered waste combustion and is appropriately 
addressed under CAA section 112 regulations for boilers (e.g., the 
boilers NESHAP and area source boilers standards). On the other hand, 
if materials were burned in a combustion unit without heat recovery, 
the combustion would serve no useful purpose other than destruction or 
disposal of an unwanted material, and EPA would then consider it 
appropriate to identify the material as a commercial or industrial 
waste and regulate the combustion unit under CAA section 129 as a CISWI 
unit.
    In addition, many units that are designed and operated for energy 
recovery and predominantly burn materials that are widely considered 
fuels will occasionally fire small amounts of other materials in these 
units that could be considered waste in some circumstances. However, 
these units continue to recover energy from the combustion of these 
additional materials. Thus, it is not immediately clear how EPA should 
classify such units that are designed and operated for energy recovery 
but occasionally combust waste-like materials.
    EPA has determined that for purposes of the final CISWI rules, the 
critical consideration in determining whether the unit is burning 
commercial or industrial waste is the primary function of the 
combustion unit; and the primary indicator of function is whether or 
not a unit is designed and operated to recover energy for a useful 
purpose. Accordingly, we are promulgating definitions of ``commercial 
or industrial waste'' and ``CISWI unit'' to include in the CISWI rules 
units whose design does not provide for energy recovery or that are 
operated without energy recovery. We continue to define energy recovery 
as the recovery of heat (thermal energy) for a useful purpose. The 
revised definition of ``commercial or industrial waste'' does not 
change the existing scope of the CISWI source category, but contains 
editorial revisions to more clearly express our intent, as described 
further below.
    The determination that units (such as boilers) that recover energy 
for a useful purpose are not subject to the final CISWI rules does not 
exclude them from regulation. As noted earlier, EPA has already 
regulated commercial and industrial boilers and process heaters located 
at major sources under 40 CFR part 63, subpart DDDDD (the boilers 
NESHAP). EPA is addressing commercial and institutional boilers and 
process heaters located at area sources under the CAA section 112 area 
source boilers standards, currently under development. Additionally, 
other categories of specialty combustion units, such as hazardous waste 
combustors and cement kilns are regulated under separate section 112 
NESHAP. Section 112 addresses hazardous air pollutants such as 
hazardous metals, organic compounds, and HCl.
    Comment: One commenter pointed out that despite EPA's claim that it 
has ``considerable discretion to regulate a variety of sources as solid 
waste incinerators,'' CAA section 129(a)(1) requires EPA to ``establish 
performance standards and other requirements pursuant to section 7411 
of this title and this section for each category of solid waste 
incineration units.'' (See 42 U.S.C. 7429(a)(1)(A) (emphasis added).) 
The commenter believes these categories are very broad, based on 
language in section 129(g)(1), which defines ``solid waste incineration 
unit'' to mean ``a distinct operating unit of any facility which 
combusts any solid waste material from commercial or industrial 
establishments.'' (See 42 U.S.C. 7429(g)(1).) The commenter also argued 
that the text of section 129 shows that Congress expressly considered 
the issue of whether to regulate heat recovery units under section 129 
by providing only limited, specific exemptions. Thus, according to the 
commenter's

[[Page 55574]]

interpretation of the statute, EPA must set section 129 standards for 
any unit that combusts any solid waste, with the narrow exception of 
the categories of energy recovery units specifically enumerated in 
section 129(g)(1). The commenter also asserts that EPA acknowledged 
this position in the hospital, medical, and infectious waste 
incinerator (HMIWI) rules, by stating the following:

    The EPA disagrees with commenters that contend EPA has no 
authority to regulate cement kilns under section 129. Section 
129(a)(1)(A) requires the Administrator to establish performance 
standards and other requirements for each category of solid waste 
incineration units. Congress specifically listed in section 129 
various categories of solid waste incineration units that EPA must 
regulate. Section 129(g)(1) broadly defines solid waste incineration 
unit as ``a distinct operating unit of any facility which combusts 
any solid waste material * * *'' This definition clearly indicates 
Congress' intent to regulate more than just incinerators because the 
definition sweeps within its scope any facility that is combusting 
any solid waste.

    Response: Inherent in EPA's implementation of CAA section 129 is 
the discretion to identify the types of sources covered by the 
statutorily undefined category of commercial or industrial solid waste 
incineration units. Considered as a whole, the statutory provisions of 
section 129(a), (g), and (h) require that EPA determine, as part of the 
regulatory process, which combustion units should be subject to 
regulation under section 129. For example, as explained in the previous 
response, EPA has determined that boilers combusting materials for 
energy recovery are subject to section 112 and hence, are not subject 
to section 129.
    The commenter relies on the statutory definition of solid waste 
incineration unit to argue that any unit combusting any solid waste at 
any time should be covered under CISWI. However, we do not agree with 
this broad interpretation of the definition of ``solid waste 
incineration unit'' based on the use of the modifier ``any.'' We 
believe the word ``any'' should be interpreted within the broader frame 
of reference of its statutory context, consistent with observations of 
the Supreme Court in Nixon v. Missouri Municipal League, 541 U.S. 125, 
124 S. Ct. 1555 (2004). In this recent opinion, the Court observed that 
Congress's understanding of ``any'' can differ depending on the 
statutory setting. (See 124 S. Ct. at 1561.) Nixon and a related line 
of cases support looking for indications in the statute that suggest a 
more limited meaning of the modified term is possible or intended. (See 
70 FR 33838, 33842 (June 10, 2005).) Indications of a more limited 
meaning can be found within the definition of solid waste incineration 
unit in CAA section 129(g)(1) and CAA section 129(h).
    The commenter argues that EPA should stop reading the definition of 
``solid waste incineration unit'' in CAA section 129(g)(1) after the 
phrase ``any solid waste material.'' Thus, according to the commenter, 
a CISWI unit must include ``any facility which combusts any solid waste 
material.'' However, the commenter fails to give meaning to the 
remainder of the sentence in section 129(g)(1), which provides that a 
solid waste incineration unit under section 129 includes a facility 
that combusts ``any solid waste material from commercial or industrial 
establishments.'' There is a distinction between ``any solid waste 
material'' and ``any solid waste material from commercial or industrial 
establishments.'' In order to identify solid waste material from 
commercial and industrial establishments, we have promulgated a 
definition of ``commercial or industrial waste'' which incorporates the 
broader definition of ``solid waste.'' As discussed in the earlier 
response, because it is sometimes not obvious whether a commercial and 
industrial establishment treats material as a waste or as a fuel, we 
have developed the definition of commercial or industrial waste to 
identify solid waste from commercial and industrial establishments 
based on whether the waste is burned without energy recovery.
    Moreover, we do not agree that the ``small power production 
facilities'' or ``qualifying cogeneration facilities'' described in CAA 
section 129(g)(1) are the only types of energy recovery facilities that 
are properly excluded from the CISWI source category. To the extent 
that another type of energy recovery facility is not considered to be 
combusting solid waste from a commercial and industrial establishment, 
that facility should also be excluded from the CISWI source category. 
We do not read section 129(g)(1) to establish an exclusive list of 
excluded sources. See National Wildlife Federation v. Gorsuch, 693 F.2d 
156, 172 (D.C. Cir. 1982) (use of the term ``includes'' allows for 
additional, unstated meanings); Chemehuevi Indian Tribe v. California 
St. Bd. of Equalization, 757 F.2d 1047, 1054 (9th Cir. 1985), rev'd on 
different grounds, 106 S. Ct. 289 (1985) (``includes'' is a term of 
enlargement, not of limitation); United States v. Huber, 603 F.2d 387, 
394 (2d Cir. 1979), cert. denied, 100 S. Ct. 1312 (1980) (use of the 
word ``includes,'' rather than a more restrictive term such as 
``means,'' indicates that the list is not exhaustive but merely 
illustrative).
    Furthermore, the definition of ``solid waste incineration unit'' 
applies to all categories of units subject to CAA section 129. The 
enumerated exclusions in CAA section 129(g)(1) ensure that specific 
types of facilities are not included in any category under section 129. 
Thus, we do not read these exclusions to be an exclusive list of energy 
recovery facilities that are not included in the CISWI source category.
    Furthermore, CAA section 129(h)(2) states that any unit subject to 
a section 129 standard cannot also be subject to a CAA section 112(d) 
standard. The rules of logic support the position that the 
contrapositive of that statement is equally true--any unit subject to a 
section 112(d) standard cannot also be subject to a section 129 
standard. This indicates a Congressional intent not to give the word 
``any'' the broad meaning suggested by the commenter because it would 
require that EPA periodically address units regulated by section 112 
under section 129 at times when such units combust solid waste 
material, even if such units are designed and operated for energy 
recovery.
    The quote cited by the commenter regarding cement kilns expressed 
EPA's position that we have the authority to regulate units under CAA 
section 129 based on their primary function. Thus, we indicated that if 
we determined that a unit, that might be called a cement kiln was 
actually functioning more like an incinerator, we would have the 
authority to regulate that unit under section 129 even though it was 
not identified as an incinerator. However, we did not make a finding at 
that time that we were required to regulate cement kilns under section 
129 because they functioned as incinerators. In addition, it appears 
from the quote that we focused at that time only on the phrase ``any 
solid waste material'' without considering the additional language 
``from commercial or industrial establishments'' that is relevant to 
the CISWI source category.
    Ultimately, we determined that cement kilns should not be regulated 
in the final HMIWI rules, but instead should be regulated under CAA 
section 112. Cement kilns, including those burning nonhazardous solid 
waste for purposes of energy recovery, have been regulated since 1999 
under the portland cement manufacturing industry NESHAP, which is based 
on MACT. The NESHAP regulates both major and area sources, and its 
requirements reduce emissions of PM, multiple metals,

[[Page 55575]]

dioxins/furans, and total hydrocarbons (which are a surrogate for other 
organic HAP including polycyclic organic matter (POM), benzene, 
toluene, and formaldehyde). The final rule has already been implemented 
and sources are complying with it. As discussed above, CAA section 
129(h)(2) is clear that regulations under sections 129 and 112 are 
mutually exclusive. Accordingly, sources such as cement kilns, boilers 
and process heaters that are subject to section 112 standards are not 
CISWI units.
    Comment: One commenter believes that electric steam generating 
units that are already subject to NSPS controls under 40 CFR part 60, 
subparts Da or Db, should not be subject to regulation under CAA 
section 129. The commenter stated that EPA did not consider electric 
utilities that co-combust solid waste with fuel in its rulemaking 
activities, and, therefore, EPA's regulatory impact analysis did not 
account for such units. The commenter urged EPA to clarify that the 
definitions of ``commercial or industrial waste'' and ``commercial and 
industrial solid waste incineration (CISWI) unit'' do not inadvertently 
result in the CAA section 129 program regulating electric utility 
boilers, including circumstances where such boilers co-combust very 
small amounts of nonhazardous solid waste with fuel during the 
production of power. An example is periodic boiler cleaning, when 
deposits that accumulate on the interior of boiler tube walls are 
removed with a cleaning agent. The resulting material is combusted in 
the boiler with fuel while the boiler is being operated to recover 
energy and produce power. Combustion is a highly effective method of 
destroying such materials. The commenter pointed out that EPA agreed 
with their comment on the November 1999 CISWI proposal that the 
regulatory text swept too broadly by potentially capturing the episodic 
circumstances in which electric utilities combust small amounts of such 
nonhazardous solid waste with fuel. The commenter also stated that the 
legislative history makes clear that Congress intended section 129 to 
apply only to units dedicated to solid waste combustion and cited 
specific legislative history supporting this point. The commenter 
further stated that application of section 129 to electric utility 
boilers would be at odds with CAA section 112, and the language of the 
CAA makes clear Congress's intent for EPA to regulate nonhazardous 
waste combustion sources under either CAA section 129 or CAA section 
112, but not both.
    Response: We agree that electric utility boilers should not be 
covered by the final CISWI rules because they are designed and operated 
for purposes of energy recovery and do not function as incinerators. We 
addressed this issue in the November 2000 CISWI comment response 
document (EPA-453/R-00-008). Electric utility boilers are regulated 
under authorities other than CAA section 129. Furthermore, the wording 
of CAA section 129(h) makes clear the Congressional intent for CAA 
regulations under CAA section 112 or section 129 to be mutually 
exclusive. In section 112(n)(1)(A), Congress set forth the limited 
circumstances under which EPA could regulate electric utility boilers 
under section 112. First Congress instructed EPA to complete a study of 
the hazards to public health reasonably expected to occur as a result 
of emissions by electric utility steam generating units of pollutants 
listed in section 112 after imposition of the requirements of the CAA. 
Then it required EPA to regulate electric utility steam generating 
units under section 112 if the Administrator finds such regulation is 
appropriate and necessary considering the results of the study required 
by section 112(n). EPA recently determined that it was neither 
appropriate nor necessary to regulate electric utility boilers under 
Section 112. (See 70 FR 15994, March 29, 2005.) The fact that the CAA 
specifically addressed electric utilities under section 112 indicates 
that Congress did not intend them to be regulated under section 129. 
Similarly, since promulgation of the final CISWI rules, EPA promulgated 
section 112 regulations for industrial, commercial and institutional 
boilers (40 CFR part 63, subpart DDDDD). That final rule applies to 
some electric steam generating units (e.g., independent power 
producers). The language of CAA section 112(h) makes clear the 
Congressional intent for CAA regulation under section 129 or section 
112 to be mutually exclusive. Accordingly, sources subject to section 
112 standards are not CISWI units. We are making minor adjustments to 
the definition of ``commercial or industrial waste'' to clarify our 
intent that boilers operated for energy recovery are not subject to 
CISWI, even if such units combust, along with other fuels, a small 
amount of material that might, under some circumstances, be considered 
waste. The revised definition clarifies that the critical consideration 
in determining whether a unit is burning commercial or industrial waste 
is the function of the combustion unit, and the primary indicator of 
function is whether or not the unit is designed and operated to recover 
energy for a useful purpose.
    The reference definition of energy recovery, which has not been 
changed, incorporates the concept of recovering thermal energy for 
``useful purposes.'' The revised definition of ``commercial or 
industrial'' waste excludes from CISWI units (such as boilers) whose 
design provides for energy recovery and that are operated for energy 
recovery. However, units designed and operated without energy recovery 
remain subject to the CISWI rules. Thus, we believe the revised 
definition of ``commercial or industrial waste'' is sufficiently clear 
to exclude utility steam generating units from the CISWI rules.
    Comment: One commenter strongly believes that a unit that 
incinerates solid waste at a rate of less than 1,000 pounds per hour 
(lb/hr) and recovers heat from the outside of the burn chamber of the 
unit for useful purposes should be exempt from the final CISWI rules. 
The commenter believes that such units are necessary in remote 
locations in northern climates for disposal of small volumes of solid 
waste and to generate heat as a useful resource.
    Response: The commenter has not provided any specific data to 
support the technical or legal basis for a size cutoff. However, at 
this time, waste heat recovery units are not covered under CISWI 
because we have not assessed the impacts of including such units in the 
final CISWI rules. An impacts assessment is necessary, but is best done 
when we respond to the CISWI remand and can perform comprehensive 
analyses that address the addition of waste heat recovery units, any 
questions on the applicability of the CISWI rules that may be raised by 
promulgation of rules for the OSWI source category, and remand issues 
regarding determination of the MACT floor and emission limits. In a 
subsequent rulemaking action in response to the CISWI remand, we intend 
to propose additional regulatory language to address units with only 
waste heat recovery and assess the impacts of the inclusion of these 
units in the CISWI source category.
    Comment: One commenter strongly supports EPA's approach of not 
specifying a particular level of British thermal units per pound (Btu/
lb) as a regulatory threshold. The commenter also included a discussion 
of the 5,000 Btu/lb threshold that EPA had previously proposed in the 
CISWI rules, and pointed out that valid energy recovery could be 
obtained from materials with lower Btu values. The commenter indicated 
(in attached comments submitted in response to previous rulemakings) 
that valid energy

[[Page 55576]]

recovery from the cement kiln process has been obtained with materials 
with heating values between 996 and 1,948 Btu/lb, but recommended that, 
if EPA does adopt a Btu threshold, a threshold of 3,000 Btu/lb is 
appropriate and conservatively high.
    Response: The EPA agrees that a Btu threshold is not needed for 
reasons described in the February 2004 notice and the 2000 CISWI 
promulgation preamble. In the preamble to the December 1, 2000 final 
CISWI rules (65 FR 75342), EPA summarized commenters' statements that 
``* * * the universe of materials burned for energy recovery is much 
broader than those defined as ``fuels.'' For example, several of 
today's combustion technologies and some new emerging technologies can 
burn materials for energy recovery having heat values less than the 
proposed 5,000 Btu/lb threshold for considering a material a fuel.'' 
The EPA responded that ``* * * we agree that several of today's 
combustion technologies, including some emerging technologies, may be 
capable of burning materials with a heat value of less than 5,000 Btu/
lb to recover energy. Therefore, we have deleted the requirement from 
the definition of solid waste in the final NSPS and EG.'' We still 
maintain this position. In addition to the information submitted by the 
commenter stating that cement kilns can recover heat from materials in 
the 1,000 to 2,000 Btu/lb range, EPA found examples of fluidized bed 
combustion units and other technologies, used at pulp and paper mills 
and for other utility, industrial, or commercial uses, that recover 
useful energy from sludges and other materials with low Btu contents 
(e.g., in the range of 1,000 to 3,800 Btu/lb). There is no bright-line 
Btu value that can be used to distinguish if a material is a fuel 
burned for energy recovery or a waste disposed of for purposes other 
than energy recovery. The approach taken in the February 2004 proposed 
definition is more workable than a Btu/lb cutoff.

B. Comments on the Definition of CISWI Unit

    Comment: One commenter supports the definition of ``CISWI unit,'' 
but suggested various clarifications to better express the intent of 
the definitions.
    Response: Although we did not adopt any specific language provided 
by the commenter, we amended the definitions to remove redundant 
language and to better express our intent. For example, we are removing 
the following phrase from the definition of ``commercial or industrial 
waste'': ``(including field erected, modular, and custom built 
incineration units operating with starved or excess air).'' This 
language is already contained within the definition of ``CISWI unit'' 
and need not be included in the definition of the waste.

C. Comments on the Definition of Commercial or Industrial Waste

    Comment: One commenter supports EPA's definition of ``commercial or 
industrial waste.'' The commenter agrees that, considering high energy 
costs, materials burned for heat recovery should not be considered 
solid waste. The commenter also agrees that materials burned without 
heat recovery for a useful purpose should be regulated as commercial 
and industrial solid waste.
    Response: We are promulgating the definition proposed in the 
February 17, 2004 Federal Register notice, with minor clarifications, 
and, as described elsewhere in this preamble, we are not including 
units with waste heat recovery in the final CISWI rules at this time.
    Comment: One commenter agrees with the proposed definition of 
``commercial or industrial waste,'' but suggested some rewording for 
clarity.
    Response: We agree with the commenter that there is room to improve 
the clarity of the proposed definition and have made some modifications 
to the definitions of ``commercial or industrial waste'' with this in 
mind. However, we have reorganized the proposed definition in a 
different manner than suggested by the commenter. We believe our 
modified definition is clearer than the reworded definition of 
commercial or industrial waste provided by the commenter. The 
commenter's definition does not reflect our decision to omit the phrase 
``combusted for reasons that do not include the recovery of heat for a 
useful purpose'' and insert the phrase ``whose design does not provide 
for energy recovery (as defined in this subpart)'' to better reflect 
the key principal that we discussed in the preamble of the proposed 
rule. Furthermore, EPA's revised definition reflects our decision not 
to regulate units with only waste heat recovery at this time, but to 
propose to regulate such units when we respond to the remand of the 
final CISWI rules.

D. Comments on the Definition of Solid Waste

    Comments: One commenter stated that EPA's arguments about the 
definition of solid waste are irrelevant and without merit. Pointing to 
section 129(g)(6) of the CAA, which provides that solid waste shall 
have the meanings established by EPA pursuant to the SWDA, the 
commenter argues that EPA has established only one ``comprehensive 
definition'' of solid waste under the SWDA: the definition in 40 CFR 
261.2. (See 69 FR 7395/2.) Furthermore, the commenter asserts that this 
definition was the only comprehensive definition that existed when 
Congress enacted section 129, which, in the commenter's view, indicates 
that Congress intended EPA to use that definition. The commenter made 
this point in an attempt to refute EPA's argument th