[Federal Register Volume 76, Number 54 (Monday, March 21, 2011)]
[Rules and Regulations]
[Pages 15704-15790]
[FR Doc No: 2011-4495]

Vol. 76

Monday,

No. 54

March 21, 2011

Part VI

Environmental Protection Agency

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40 CFR Part 60

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

Federal Register / Vol. 76 , No. 54 / Monday, March 21, 2011 / Rules
and Regulations

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 60

[EPA-HQ-OAR-2003-0119; FRL-9273-4]
RIN 2060-AO12

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.

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SUMMARY: This action promulgates EPA's final response to the 2001
voluntary remand of the December 1, 2000, new source performance
standards and emission guidelines for commercial and industrial solid
waste incineration units and the vacatur and remand of several
definitions by the District of Columbia Circuit Court of Appeals in
2007. In addition, this action includes the 5-year technology review of
the new source performance standards and emission guidelines required
under section 129 of the Clean Air Act. This action also promulgates
other amendments that EPA believes are necessary to address air
emissions from commercial and industrial solid waste incineration
units.

DATES: The final rule is effective on May 20, 2011. The incorporation
by reference of certain publications listed in the final rule are
approved by the Director of the Federal Register as of May 20, 2011.

ADDRESSES: EPA established a single docket under Docket ID Number EPA-
HQ-OAR-2003-0119 for this action. All documents in the docket are
listed on the http://www.regulations.gov Web site. Although listed in
the index, some information is not publicly available, e.g.,
confidential business information 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 through http://www.regulations.gov, or
in hard copy at EPA's Docket Center, Public Reading Room, EPA West
Building, Room 3334, 1301 Constitution Avenue, NW., Washington, DC
20004. This Docket Facility 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<PHONE_NUMBER>, and the telephone number for the
EPA Docket Center is<PHONE_NUMBER>.

FOR FURTHER INFORMATION CONTACT: Ms. Toni Jones, Natural Resources and
Commerce Group, Sector Policies and Programs Division (E143-03),
Environmental Protection Agency, Research Triangle Park, North Carolina
27711; telephone number:<PHONE_NUMBER>; facsimile number: (919) 541-
3470; e-mail address<EMAIL_ADDRESS>or Ms. Charlene Spells,
Natural Resources and Commerce Group, Sector Policies and Programs
Division (E143-03), Environmental Protection Agency, Research Triangle
Park, North Carolina 27711; telephone number:<PHONE_NUMBER>; facsimile
number:<PHONE_NUMBER>; e-mail address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION: Acronyms and Abbreviations. The following
acronyms and abbreviations are used in this document.

7-PAH 7 Polyaromatic Hydrocarbons
16-PAH 16 Polyaromatic Hydrocarbons
ACI Activated Carbon Injection
ANSI American National Standards Institute
ASME American Society of Mechanical Engineers
ASTM American Society for Testing and Materials
BAT Best Available Technology
CAA Clean Air Act
Cd Cadmium
CDX Central Data Exchange
CEMS Continuous Emissions Monitoring Systems
CFR Code of Federal Regulations
CISWI Commercial and Industrial Solid Waste Incineration
CO Carbon Monoxide
CO2 Carbon Dioxide
Catalyst Carbon Monoxide Oxidation Catalyst
The Court U.S. Court of Appeals for the District of Columbia Circuit
CSA Canadian Standards Association
CWA Clean Water Act
D/F Dioxin/Furan
DIFF Dry Sorbent Injection Fabric Filter
dscf Dry Standard Cubic Foot
dscm Dry Standard Cubic Meter
EG Emission Guidelines
EJ Environmental Justice
EMPC Estimated Maximum Possible Concentration
EOM Extractable Organic Matter
ERT Electronic Reporting Tool
ERU Energy Recovery Unit
ESP Electrostatic Precipitator
FF Fabric Filters
HAP Hazardous Air Pollutants
HCl Hydrogen Chloride
Hg Mercury
HMI Hospital, Medical and Infectious
HMIWI Hospital, Medical and Infectious Waste Incineration
HWC Hazardous Waste Combustor
ICR Information Collection Request
ISO International Standards Organization
LBMS Linkageless Burner Management System
LML Lowest Measured Level
MACT Maximum Achievable Control Technology
MDL Method Detection Level
mg/dscm Milligrams per Dry Standard Cubic Meter
mmBtu/hr Million British Thermal Units per Hour
MSW Municipal Solid Waste
MW Megawatts
MWC Municipal Waste Combustor
NAAQS National Ambient Air Quality Standards
NAICS North American Industrial Classification System
ND Nondetect
NESHAP National Emission Standards for Hazardous Air Pollutants
ng/dscm Nanograms per Dry Standard Cubic Meter
NOX Nitrogen Oxides
NSPS New Source Performance Standards
NTTAA National Technology Transfer and Advancement Act
OAQPS Office of Air Quality Planning and Standards
O&M Operations and Maintenance
OMB Office of Management and Budget
OP Office of Policy
OSWI Other Solid Waste Incineration
Pb Lead
PCBs Polychlorinated Biphenyls
PCDD Polychlorinated Dibenzodioxins
PCDF Polychlorinated Dibenzofurans
PM Particulate Matter
POM Polycyclic Organic Matter
ppm Parts Per Million
ppmv Parts Per Million by Volume
ppmvd Parts Per Million by Dry Volume
PRA Paper Reduction Act
PS Performance Specification
QA/QC Quality Assurance/Quality Control
RCRA Resource Conservation and Recovery Act
RFA Regulatory Flexibility Act
RIA Regulatory Impact Analysis
RIN Regulatory Information Number
RTO Regenerative Thermal Oxidizer
SCR Selective Catalytic Reduction
SARU Sulfuric Acid Regeneration Unit
SNCR Selective Noncatalytic Reduction
SO2 Sulfur Dioxide
SSI Sewage Sludge Incineration
SSM Startup, Shutdown, and Malfunction
SWDA Solid Waste Disposal Act
TBtu Tera British Thermal Unit
TEF Total Equivalency Factor
TEQ Toxic Equivalency
TMB Total Mass Basis
tpy Tons Per Year
TRI Toxics Release Inventory
TTN Technology Transfer Network
ug/dscm Micrograms per Dry Standard Cubic Meter
UMRA Unfunded Mandates Reform Act
UL Upper Limit
UPL Upper Prediction Limit
UTL Upper Tolerance Limit
VCS Voluntary Consensus Standards
WWW Worldwide Web

    Organization of this document. The information presented in this
preamble is organized as follows:

I. General Information
    A. Does this action apply to me?

    B. Where can I get a copy of this document?
    C. Judicial Review
II. Background Information
    A. What is the statutory authority for this final rule?
    B. What is the history of the CISWI standards?
    C. How is the solid waste definition addressed in this final
rule?
    D. What is the relationship between the final rule and other
combustion rules?
    E. What is EPA's approach for conducting a 5-year review under
CAA section 129(a)(5)?
    F. What is the relationship of this final action to section
112(c)(6) of the CAA?
III. Summary of the Final Rule
    A. Which units are affected by this final rule?
    B. What are the emission limits in the final rule?
    C. What are the testing and monitoring requirements?
    D. What are the requirements during periods of SSM?
    E. How do the rule amendments affect the applicability of the
2000 NSPS and EG?
    F. What is the compliance schedule?
    G. What is the state plan implementation schedule?
    H. What are the requirements for submission of emissions test
results to EPA?
    I. What are the costs and benefits of this final rule?
IV. Summary of Significant Changes Since Proposal
V. Public Comments
    A. Legal and Applicability Issues, Compliance Schedule, and
Certification Procedures
    B. MACT Floor Analysis
    C. Control Technology Assumptions for the Floor and Beyond-the-
Floor
    D. Rationale for Subcategories
    E. Emission Limits
    F. New Data/Corrections to Existing Data
    G. Testing and Monitoring
    H. Startup, Shutdown, and Malfunction Requirements
    I. Notification, Recordkeeping and Reporting Requirements
    J. Air Curtain Incinerators
    K. Role of States
    L. Biased Data Collection From Phase II ICR Testing
VI. Impacts of the Action
    A. What are the primary air impacts?
    B. What are the water and solid waste impacts?
    C. What are the energy impacts?
    D. What are the secondary air impacts?
    E. What are the cost and economic impacts?
    F. What are the benefits?
VII. Statutory and Executive Order Reviews
    A. Executive Order 12866 and 13563: 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 and Advancement Act
    J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
    K. Congressional Review Act

I. General Information

A. Does this action apply to me?

    Categories and entities potentially affected by the final action
are those that operate CISWI units. The NSPS and EG, hereinafter
referred to as ``standards,'' for CISWI affect the following categories
of sources:

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              Category                      NAICS code                                 Examples of potentially regulated entities
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Any industrial or commercial         211, 212, 486...........  Mining, oil and gas exploration operations; pipeline operators.
 facility using a solid waste
 incinerator.
                                     221.....................  Utility providers.
                                     321, 322, 337...........  Manufacturers of wood products; manufacturers of pulp, paper and paperboard;
                                                                manufacturers of furniture and related products.
                                     325, 326................  Manufacturers of chemicals and allied products; manufacturers of plastics and rubber
                                                                products.
                                     327.....................  Manufacturers of cement; nonmetallic mineral product manufacturing.
                                     333, 336................  Manufacturers of machinery; manufacturers of transportation equipment.
                                     423, 44.................  Merchant wholesalers, durable goods; retail trade.
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    This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be affected by the final
action. If you have any questions regarding the applicability of the
final action to a particular entity, contact the person listed in the
preceding FOR FURTHER INFORMATION CONTACT section.

B. Where can I get a copy of this document?

    In addition to being available in the docket, an electronic copy of
the final action will also be available on the WWW through the TTN.
Following signature, a copy of the final action will be posted on the
TTN's policy and guidance page for newly proposed or promulgated rules
at the following address: http://www.epa.gov/ttn/oarpg. The TTN
provides information and technology exchange in various areas of air
pollution control.

C. Judicial Review

    Under CAA section 307(b)(1), judicial review of this final rule is
available only by filing a petition for review in the Court by May 20,
2011. Section 307(d)(7)(B) of the CAA further provides that ``only an
objection to a rule or procedure which was raised with reasonable
specificity during the period for public comment can be raised during
judicial review.'' This section also provides a mechanism for us to
convene a proceeding for reconsideration, ``[i]f the person raising an
objection can demonstrate to EPA that it was impracticable to raise
such objection within [the period for public comment] or if the grounds
for such objection arose after the period for public comment (but
within the time specified for judicial review) and if such objection is
of central relevance to the outcome of the rule.'' Any person seeking
to make such a demonstration to us should submit a Petition for
Reconsideration to the Office of the Administrator, Environmental
Protection Agency, Room 3000, Ariel Rios Building, 1200 Pennsylvania
Ave., NW., Washington, DC 20004, with a copy to both of the contacts
listed in the preceding FOR FURTHER INFORMATION CONTACT section, and
the Associate General Counsel for the Air and Radiation Law Office,
Office of General Counsel (Mail Code 2344A), Environmental Protection
Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20004. Note, under
CAA section 307(b)(2), the requirements established by this final rule
may not be challenged separately in any civil or criminal proceedings
brought by EPA to enforce these requirements.

II. Background Information

A. What is the statutory authority for this final rule?

    Section 129 of the CAA, entitled ``Solid Waste Combustion,''
requires EPA to develop and adopt standards for solid waste
incineration units pursuant to CAA sections 111 and 129. Section
129(a)(1)(A) of the CAA requires EPA to establish performance
standards, including emission limitations, for ``solid waste
incineration units'' generally and, in particular, for ``solid waste
incineration units combusting commercial or industrial waste'' (CAA
section 129(a)(1)(D)). Section 129 of the CAA defines ``solid waste
incineration unit'' as ``a distinct operating unit of any facility
which combusts any solid waste material from commercial or industrial
establishments or the general public'' (section 129(g)(1)). Section 129
of the CAA also provides that ``solid waste'' shall have the meaning
established by EPA pursuant to its authority under the RCRA (section
129(g)(6)).
    In Natural Resources Defense Council v. EPA, 489 F.3d 1250 (DC Cir.
2007), the Court vacated the CISWI Definitions Rule (70 FR 55568,
September 22, 2005), which EPA issued pursuant to CAA section
129(a)(1)(D). In that rule, EPA defined the term ``commercial or
industrial solid waste incineration unit'' to mean a combustion unit
that combusts ``commercial or industrial waste.'' The rule defined
``commercial or industrial waste'' to mean waste combusted at a unit
that does not recover thermal energy from the combustion for a useful
purpose. Under these definitions, only those units that combusted
commercial or industrial waste and were not designed to, or did not
operate to, recover thermal energy from the combustion, were subject to
CAA section 129 standards. In vacating the rule, the Court found that
the definitions in the amendments to the CISWI regulations were
inconsistent with the CAA. Specifically, the Court held that the term
``solid waste incineration unit'' in CAA section 129(g)(1)
``unambiguously include[s] among the incineration units subject to its
standards any facility that combusts any commercial or industrial solid
waste material at all--subject to the four statutory exceptions
identified [in CAA section 129(g)(1)]'' NRDC v. EPA, 489 F.3d at 1257-
58.
    In response to the Court's vacatur of the CISWI Definitions Rule,
EPA initiated a rulemaking to define which non-hazardous secondary
materials is ``solid waste'' for purposes of subtitle D (non-hazardous
waste) of RCRA when burned in a combustion unit. See 74 FR 41 (January
2, 2009) soliciting comment on whether certain non-hazardous secondary
materials used as alternative fuels or ingredients are solid wastes
within the meaning of subtitle D of the RCRA. That definition, once
established, will determine the applicability of CAA section 129(a) to
commercial and industrial combustion units.
    On the same day EPA proposed standards for CISWI units, EPA issued
a proposed definition of non-hazardous secondary materials that are
solid waste pursuant to subtitle D of RCRA (75 FR 31844, June 4, 2010).
In a parallel action to today's final CISWI rule, EPA is promulgating a
final definition of solid waste that identifies whether non-hazardous
secondary materials burned as fuels in combustion units are solid
waste. That action, hereinafter referred to as the ``Non-hazardous
Solid Waste Definition Rulemaking,'' is relevant to this proceeding
because some ERUs and waste-burning kilns combust secondary materials
in their combustion units which are defined as solid waste under the
new definition. Units that combust solid waste (as defined under the
new non-hazardous solid waste definition) will be subject to standards
in the final CAA section 129 CISWI rules rather than to the standards
under CAA section 112 applicable to boilers, process heaters, and
cement kilns.
    At proposal, we acknowledged that we had incomplete information on
the exact nature of the non-hazardous secondary materials that ERUs and
waste-burning kilns combust. For example, we indicated that we lacked
complete information concerning the provider(s) of the non-hazardous
secondary materials, how much processing the non-hazardous secondary
materials may have undergone, if any, and other issues potentially
relevant in a determination as to whether non-hazardous secondary
materials are solid waste, all information relevant not only in this
rulemaking but also in developing a definition in the concurrent Non-
hazardous Solid Waste Definition Rulemaking.
    In developing standards for this final rule, we used best efforts
to estimate which units would have been classified as CISWI (i.e.,
units combusting solid waste) had the final definition of non-hazardous
solid waste been in place at the time of the performance testing. The
standards (and, necessarily, the pool of best performers establishing
the floors for each standard) are based on the performance of this
universe of sources.\1\ In evaluating which sources would have been
classified as CISWI had the new definition of solid waste been
effective, EPA used the information currently available on which non-
hazardous secondary materials the sources combust, as supplemented by
information obtained from public comment and further information
gathered by EPA after the public comment period of this rule.
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    \1\ Section 112(D) MACT standards are based on the performance
of sources at a moment in time (or over some demarcated timeframe),
and EPA therefore bases those standards on performance of sources
classified as part of the source category at the time their
performance is evaluated (i.e., the time of performance testing).
However, EPA could not use this approach here. Sources combusting
non-hazardous secondary materials, the best example being
alternative fuels, were not classified as CISWI absent a regulatory
definition of solid waste classifying such secondary materials. In
order to issue the CISWI standards by the mandated promulgation
deadline, EPA thus deviated from its usual practice and based the
standards on the performance of devices which would have been
classified as CISWI had the final waste definition been in place at
the time of the performance testing even though these sources were
not CISWI at the time. There was no approach that would be based on
the sources' actual status that would have allowed EPA to complete
this CISWI rule by the time of the mandated deadline for
promulgation.
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    Energy recovery units (i.e., boilers and process heaters) and
waste-burning kilns (i.e., cement kilns) that are burning solid waste
(as defined in new section 241) will be subject to today's standards.
    Sections 111(b) and 129(a) of the CAA address emissions from new
CISWI units (i.e., NSPS) and CAA sections 111(d) and 129(b) address
emissions from existing CISWI units (i.e., EG). The NSPS are directly
enforceable federal regulations and under CAA section 129(f)(1) become
effective 6 months after promulgation. Under CAA section 129(f)(2), the
EG become effective and enforceable no later than 3 years after EPA
approves a state plan implementing the EG or 5 years after the date
they are promulgated, whichever is earlier.
    The CAA sets forth a two-stage approach to regulating emissions
from solid waste incinerator units. The statute also provides EPA with
substantial discretion to distinguish among classes, types, and sizes
of incineration units within a category while setting standards. In the
first stage of setting standards, CAA section 129(a)(2) requires EPA to
establish technology-based emission standards that reflect levels of
control EPA determines are achievable for new and existing units, after
considering costs, nonair quality health and environmental impacts and
energy requirements associated with the implementation of the
standards. Section 129(a)(5) of the CAA then directs EPA to review
those

standards and revise them as necessary every 5 years. In the second
stage, CAA section 129(h)(3) requires EPA to determine whether further
revisions of the standards are necessary in order to provide an ample
margin of safety to protect public health. See, e.g., NRDC and LEAN v.
EPA, 529 F.3d 1077, 1079-80 (D.C. Cir. 2008) addressing the similarly
required two-stage approach under CAA sections 112(d) and (f) and
upholding EPA's implementation of same.
    In setting forth the methodology EPA must use to establish the
first-stage technology-based standards for the NSPS and EG, CAA section
129(a)(2) provides that standards ``applicable to solid waste
incineration units promulgated under section 111 and this section shall
reflect the maximum degree of reduction in emissions of [certain listed
air pollutants] that the Administrator, taking into consideration the
cost of achieving such emission reduction and any nonair quality health
and environmental impacts and energy requirements, determines is
achievable for new and existing units in each category.'' This level of
control is referred to as a MACT standard.
    In promulgating a MACT standard, EPA must first calculate the
minimum stringency levels for new and existing solid waste incineration
units in a category, generally based on levels of emissions control
achieved or required to be achieved by the subject units. The minimum
level of stringency is called the MACT ``floor,'' and CAA section
129(a)(2) sets forth differing levels of minimum stringency that EPA's
standards must achieve, based on whether they regulate new and
reconstructed sources, or existing sources. For new and reconstructed
sources, CAA section 129(a)(2) provides that the ``degree of reduction
in emissions that is deemed achievable * * * shall not be less
stringent than the emissions control that is achieved in practice by
the best controlled similar unit, as determined by the Administrator.''
Emissions standards for existing units may be less stringent than
standards for new units, but ``shall not be less stringent than the
average emissions limitation achieved by the best-performing 12 percent
of units in the category.''
    Maximum Achievable Control Technology analyses involve an
assessment of the emissions from the best-performing unit or units in a
source category. The assessment can be based on actual emissions data,
knowledge of the air pollution control in place in combination with
actual emissions data, or on state regulatory requirements that may
enable EPA to estimate the actual performance of the regulated units.
For each source category, the assessment involves a review of actual
emissions data with an appropriate accounting for emissions
variability. Other methods of estimating emissions can be used, if the
methods can be shown to provide reasonable estimates of the actual
emissions performance of a source or sources. Where there is more than
one method or technology to control emissions, the analysis may result
in a series of potential regulations (called regulatory options), one
of which is selected as MACT.
    Each regulatory option EPA considers must be at least as stringent
as the CAA's minimum stringency ``floor'' requirements. EPA must
examine, but is not necessarily required to adopt, more stringent
``beyond-the-floor'' regulatory options to determine MACT. Unlike the
floor minimum stringency requirements, EPA must consider various
impacts of the more stringent regulatory options in determining whether
MACT standards are to reflect ``beyond-the-floor'' requirements. If EPA
concludes that the more stringent regulatory options have unreasonable
impacts, EPA selects the ``floor-based'' regulatory option as MACT.
However, if EPA concludes that impacts associated with ``beyond-the-
floor'' levels of control are reasonable in light of additional
emissions reductions achieved, EPA selects those levels as MACT.
    The CAA requires that MACT for new sources be no less stringent
than the emissions control achieved in practice by the best-controlled
similar unit. Under CAA section 129(a)(2), EPA determines the best
control currently in use for a given pollutant and establishes one
potential regulatory option at the emission level achieved by that
control with an appropriate accounting for emissions variability. More
stringent potential beyond-the-floor regulatory options might reflect
controls used on other sources that could be applied to the source
category in question.
    For existing sources, the CAA requires that MACT be no less
stringent than the average emissions limitation achieved by the best-
performing 12 percent of units in a source category. EPA must determine
some measure of the average emissions limitation achieved by the best-
performing 12 percent of units to form the floor regulatory option.
More stringent beyond-the-floor regulatory options reflect other or
additional controls capable of achieving better performance.

B. What is the history of the CISWI standards?

    On December 1, 2000, EPA published a notice of final rulemaking
establishing the NSPS and EG for CISWI units (60 FR 75338), hereinafter
referred to as the 2000 CISWI rule. On August 17, 2001, EPA granted a
Request for Reconsideration, pursuant to CAA section 307(d)(7)(B) of
the CAA, submitted on behalf of the National Wildlife Federation and
the Louisiana Environmental Action Network, related to the definition
of ``commercial and industrial solid waste incineration unit'' and
``commercial or industrial waste'' in EPA's CISWI rulemaking. In
granting the Petition for Reconsideration, EPA agreed to undertake
further notice and comment proceedings related to these definitions. On
January 30, 2001, Sierra Club filed a petition for review in the Court
challenging EPA's final CISWI rule. On September 6, 2001, the Court
entered an order granting EPA's motion for a voluntary remand of the
CISWI rule, without vacatur. EPA's request for a voluntary remand of
the final CISWI rule was taken to allow the EPA to address concerns
related to EPA's procedures for establishing MACT floors for CISWI
units in light of the Court's decision in Cement Kiln Recycling
Coalition v. EPA, 255 F.3d 855 (DC Cir. 2001)(Cement Kiln). Neither
EPA's granting of the Petition for Reconsideration, nor the Court's
order granting a voluntary remand, stayed, vacated, or otherwise
influenced the effectiveness of the 2000 CISWI rule. Specifically, CAA
section 307(d)(7)(B) provides that ``reconsideration shall not postpone
the effectiveness of the rule,'' except that ``[t]he effectiveness of
the rule may be stayed during such reconsideration * * * by the
Administrator or the Court for a period not to exceed three months.''
Neither EPA nor the Court stayed the effectiveness of the final CISWI
regulations in connection with the reconsideration petition. In
addition, the Court granted EPA's motion for a remand without vacatur;
therefore, the remand order had no impact on the implementation of the
2000 CISWI rule.
    On February 17, 2004, EPA published a proposed rule soliciting
comments on the definitions of ``solid waste,'' ``commercial and
industrial waste,'' and ``commercial and industrial solid waste
incineration unit.'' On September 22, 2005, EPA published in the
Federal Register the final rule reflecting our decisions with respect
to the CISWI Definitions Rule. The rule was challenged and, on June 8,
2007, the Court vacated and remanded the CISWI

Definitions Rule. In vacating the rule, the Court found that CAA
section 129 unambiguously includes among the incineration units subject
to its standards, any facility that combusts any solid waste material,
subject to four statutory exceptions. While the Court vacated the CISWI
Definitions Rule, the 2000 CISWI rule remains in effect.
    On June 4, 2010, EPA proposed revised NSPS and EG for CISWI units
(75 FR 31938). Today's final action constitutes EPA's response to the
voluntary remand of the 2000 CISWI rule and to the 2007 vacatur and
remand of the CISWI Definitions Rule. In addition, these amendments
address the 5-year technology review that is required under CAA section
129(a)(5).

C. How is the solid waste definition addressed in this final rule?

    The RCRA definition of solid waste is integral in defining the
CISWI source category. EPA defines the non-hazardous secondary
materials that are solid waste under RCRA in the final Non-hazardous
Solid Waste Definition Rulemaking. At proposal, the Non-hazardous Solid
Waste Definition Rulemaking proposed a definition of solid waste and
identified an ``alternative approach'' for consideration and comment.
However, the final solid waste definition does not incorporate the
``alternative approach,'' and more closely reflects the proposed
definition of non-hazardous secondary materials that are solid waste.

D. What is the relationship between the final rule and other combustion
rules?

    These amendments address the combustion of solid waste materials
(as defined by the Administrator under RCRA in the concurrent Non-
hazardous Solid Waste Definition Rulemaking) in combustion units at
commercial and industrial facilities. If an owner or operator of a
CISWI unit permanently ceases combusting solid waste, the affected unit
would no longer be subject to this regulation under CAA section 129.
Section 112 rules of the CAA, applicable to boilers and process heaters
at major sources and boilers at area sources, are being promulgated in
parallel actions that are relevant to this action because those
standards would apply to subject boilers and process heaters that do
not combust solid waste. Boilers and process heaters that combust solid
waste are subject to CISWI as ERUs. EPA has also finalized revised CAA
section 112 NESHAP from the Portland Cement Manufacturing Industry (75
FR 21136, September 9, 2010). Cement kilns combusting solid waste are
waste-burning kilns subject to this final rule, not the otherwise
applicable NESHAP.

E. What is EPA's approach for conducting a 5-year review under CAA
section 129(a)(5)?

    Section 129(a)(5) of the CAA requires EPA to conduct a review of
the section 129 standards at 5-year intervals and, in accordance with
CAA sections 129 and 111, revise the standards. We do not interpret CAA
section 129(a)(5), together with CAA section 111, as requiring EPA to
recalculate MACT floors in connection with this periodic review. (71 FR
27324, 27327-28, May 10, 2006; NRDC and LEAN v. EPA, 529 F.3d 1077,
1083-84 (DC Cir. 2008) (upholding EPA's interpretation that the
periodic review requirement in CAA section 112(d)(6) does not impose an
obligation to recalculate MACT floors). Rather, in conducting such
periodic reviews, EPA attempts to assess the performance of and
variability associated with control measures affecting emissions
performance at sources in the subject source category (including the
installed emissions control equipment), along with recent developments
in practices, processes, and control technologies, and determines
whether it is appropriate to revise the standards. This is the same
general approach taken by EPA in periodically reviewing CAA section 111
standards, because CAA section 111 contains a similar review and revise
provision.
    Our obligation to conduct a 5-year review based on implementation
of the 2000 CISWI rule is fulfilled with the finalization of these
CISWI standards. This action responds to the vacatur and remand of the
CISWI Definition Rule and the voluntary remand of the 2000 CISWI NSPS
and EG, and, in this response, EPA is requiring new standards based on
a MACT methodology that is consistent with the CAA and District of
Columbia Circuit Court precedent. The MACT levels required herein
reflect MACT floor levels determined by current emissions data from
CISWI units, and, therefore, reflect the current performance of the
best-performing unit or units subject to the CISWI standards.
Consequently, we believe that our obligation to conduct a 5-year review
based on implementation of the 2000 CISWI rule is fulfilled.
    Our conclusion is supported by the fact that the revised MACT
standards included in this final remand response are based on the
available performance data for the currently operating CISWI units,
including those units that are subject to the 2000 CISWI rule and those
units that will be subject to the CISWI standards for the first time
based on the final Non-hazardous Solid Waste Definition Rulemaking
under RCRA. In establishing MACT floors based on currently available
emissions information, we address the technology review's goals of
assessing the performance efficiency of the installed equipment and
ensuring that the emission limits reflect the performance of the
technologies required by the MACT standards. In addition, in
establishing these final standards, we considered whether new
technologies, processes, and improvements in practices have been
demonstrated at sources subject to the 2000 CISWI rule and at sources
that will be subject to these proposed standards for the first time
based on the proposed definition of solid waste. Accordingly, the
remand response in this final action fulfills EPA's obligations
regarding the 5-year review of the CISWI standards. Further discussion
of the EPA's response to the CAA section 129(a)(5) 5-year review is
found in section III.B of the proposal preamble (75 FR 31946).

F. What is the relationship of this final action to section 112(c)(6)
of the CAA?

    Section 112(c)(6) of the CAA requires EPA to identify categories of
sources of seven specified pollutants to assure that sources accounting
for not less than 90 percent of the aggregate emissions of each such
pollutant are subject to standards under CAA section 112(d)(2) or
112(d)(4). EPA has identified certain CISWI units as sources necessary
to meet the 90 percent requirement under section 112(c)(6). In the
Federal Register notice ``Source Category Listing for Section 112(d)(2)
Rulemaking Pursuant to Section 112(c)(6) Requirements'', 63 FR 17838,
17849, Table 2 (1998), EPA identified source categories that must be
``subject to regulation'' for purposes of CAA section 112(c)(6).
Included in that list are cement kilns and combustion units (e.g.,
major source boilers and process heaters). Cement kilns, boilers, and
process heaters that combust solid waste are subject to the CAA section
129 standards for CISWI as either waste-burning kilns or ERUs. These
CISWI units emit five of the seven CAA section 112(c)(6) pollutants:
POM, dioxins, furans, Hg and PCBs. The POM emitted by CISWI is composed
of 7-PAH and 16-PAH.
    For purposes of CAA section 112(c)(6), EPA has determined that
standards promulgated under CAA section 129 are substantively
equivalent to those promulgated under CAA section 112(d). (63 FR 17845;
62 FR 33625, 33632 (1997)). As discussed in more detail in response to
comments on

this issue, the CAA section 129 standards effectively control emissions
of the five identified CAA section 112(c)(6) pollutants. Further, since
CAA section 129(h)(2) precludes EPA from regulating CISWI units under
CAA section 112(d), EPA cannot further regulate the emissions of
112(c)(6) pollutants from CISWI units under CAA section 112(d). As a
result, EPA considers emissions of these five pollutants from waste-
burning kilns and ERUs ``subject to standards'' for purposes of CAA
section 112(c)(6). The remaining CISWI subcategories will be subject to
MACT standards either in this action or in a future action, but
regulation of the remaining subcategories is not required for EPA to
complete its 112(c)(6) obligations.

III. Summary of the Final Rule

A. Which units are affected by this final rule?

    This final rule defines a CISWI unit as any combustion unit at a
commercial or industrial facility that is used to combust solid waste
(as defined under RCRA). (40 CFR 60.2265 (NSPS) and 60.2875 (EG)).
Therefore, in this final rule, CISWI units subject to standards in this
final rule include incinerators designed to burn discarded waste
materials; units designed for heat recovery that combust solid waste
materials (i.e., ERUs that would be boilers or process heaters if they
did not burn solid waste); and waste burning kilns (i.e., units that
would be cement kilns if they did not burn solid waste); we also define
other CISWI units that are not subject to standards in this final
action. The final rule contains definitions of the four subcategories
of CISWI units that are subject to standards under these amendments:
incinerators, small remote incinerators, ERUs, and waste burning kilns.
At proposal, we also defined and proposed standards for burn-off ovens.
Based on information obtained during proposal, and because we do not
need such units to comply with our section 112(c)(6) obligations, we
are not finalizing standards for burn-off ovens as explained further
below in response to comments on this issue.
    We are revising the definition of CISWI unit to reflect the Court's
decision that all units burning solid waste as defined under RCRA are
to be covered by regulation under CAA section 129. To ensure
consistency with the definition of CISWI unit, we are also adding a
definition of ``solid waste incineration unit'' and removing the
definition of ``commercial and industrial waste.''
    The 2000 CISWI rule, through the definition of ``commercial and
industrial waste,'' excluded from regulation combustion units at
commercial or industrial facilities that recovered energy for a useful
purpose. We are eliminating those exemptions that were vacated by the
Court.
    Qualifying small power producers, qualifying cogeneration units,
and materials recovery units continue to be expressly exempt from
coverage pursuant to CAA exclusions from the definition of ``solid
waste incineration unit'' set forth in CAA section 129(g)(1). Units
that are required to have a permit under section 3005 of the SWDA
(i.e., hazardous waste combustion units) are also exempt from section
129 rules per CAA section 129(g)(1). Air curtain incinerators at
commercial or industrial facilities combusting ``clean wood'' waste are
also excluded from the definition of solid waste incineration unit set
forth in CAA section 129(g)(1), but that section provides that such
units must comply with opacity limits to maintain that exemption.
    Solid waste incineration units that are included within the scope
of other CAA section 129 categories include MWC units; institutional,
pathological waste incineration units (EPA intends to regulate these
units under OSWI standards); SSI units (EPA is issuing final standards
for these units in a concurrent action), and HMIWI units. These solid
waste incineration units will remain exempt from the CISWI standards.
As stated above, we created subcategories for waste-burning kilns and
ERUs, and they are subject to this final rule in light of the CISWI
Definitions Rule vacatur. We note that other CAA section 129 standards
may contain an exemption for cement kilns. Those exemptions do not
excuse waste burning kilns from compliance with these final standards.
As those other CAA section 129 rules are amended, we will clarify that
cement kilns that meet the definition of waste-burning kiln and other
CISWI units, that may be expressly exempt from those standards, are
subject to CISWI standards if they are located at a commercial or
industrial facility and they combust solid waste.

B. What are the emission limits in the final rule?

    The final MACT floor emission limits for new and existing sources
are presented in Tables 1 and 2 of this preamble. These emission limits
are based on subcategories established considering sources that we
believe are CISWI units under the final definition of non-hazardous
secondary materials, as discussed in the concurrent Non-hazardous Solid
Waste Definition Rulemaking. The final MACT floor emission limits for
existing sources in each subcategory are shown in Table 1 of this
preamble.

 Table 1--Comparison of Existing Source MACT Floor Limits for 2000 CISWI Rule and the Final MACT Floor Limits (Based on the Definition of Solid Waste in
                                               the Final Non-hazardous Solid Waste Definition Rulemaking)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Final CISWI subcategories
                                       Incinerators  (2000   -------------------------------------------------------------------------------------------
       Pollutant (units) \a\               CISWI limit)                                                   ERUs-- liquid/   Waste-burning   Small, remote
                                                               Incinerators          ERUs--solids               gas            kilns       incinerators
--------------------------------------------------------------------------------------------------------------------------------------------------------
HCl (ppmv).........................  62.....................              29  0.45......................          14 \b\          25 \b\             220
CO (ppmv)..........................  157....................          36 \b\  490 (biomass units)/59                  36             110              20
                                                                               (coal units).
Pb (mg/dscm).......................  0.04...................          0.0036  0.0036 \b\................           0.096          0.0026             2.7
Cd (mg/dscm).......................  0.004..................          0.0026  0.00051 \b\...............           0.023         0.00048            0.61
Hg (mg/dscm).......................  0.47...................          0.0054  0.00033...................      0.0013 \b\      0.0079 \b\          0.0057
PM, filterable (mg/dscm)...........  70.....................              34  250.......................             110             6.2             230
Dioxin, furans, total (ng/dscm)....  (no limit).............             4.6  0.35......................          2.9\b\            0.20           1,200
Dioxin, furans, TEQ (ng/dscm)......  0.41...................            0.13  0.059.....................         0.32\b\          0.0070              57
NOX (ppmv).........................  388....................              53  290 (biomass units)/340                 76             540             240
                                                                               (coal units).

SO2 (ppmv).........................  20.....................              11  6.2 (biomass units)/650                720              38             420
                                                                               (coal units).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ All emission limits are expressed as concentrations corrected to 7 percent oxygen.
\b\ See the memorandum ``CISWI Emission Limit Calculations for Existing and New Sources'' for details on this calculation.

    The new source MACT floor emission limits for each CISWI
subcategory are shown in Table 2 of this preamble.

 Table 2--Comparison of New Source MACT Floor Limits for 2000 CISWI Rule and the Final MACT Floor Limits (Based on the Primary Definition of Solid Waste
                                                           in the Solid Waste Definition Rule)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Final CISWI subcategories
                                    Incinerators  (2000  -----------------------------------------------------------------------------------------------
      Pollutant (units) \a\                limit)                                                                          Waste-burning   Small, remote
                                                           Incinerators         ERUs--solids          ERUs-- liquid/gas        kilns       incinerators
--------------------------------------------------------------------------------------------------------------------------------------------------------
HCl (ppmv).......................  62...................           0.091  0.45 \c\................  14b.................         3.0 \b\             200
CO (ppmv)........................  157..................              12  160 (biomass units)/ 46   36..................              90              12
                                                                           (coal units).
Pb (mg/dscm).....................  0.04.................      0.0019 \b\  0.0031..................  0.096...............          0.0026            0.26
Cd (mg/dscm).....................  0.004................          0.0023  0.00051 \c\.............  0.023...............     0.00048 \c\        0.61 \c\
Hg (mg/dscm).....................  0.47.................         0.00016  0.00033 \c\.............  0.00025 \d\.........      0.0062 \e\      0.0035 \b\
PM, filterable (mg/dscm).........  70...................              18  250 \c\.................  110.................             2.5         230 \c\
Dioxin, furans, total (ng/dscm)..  (no limit)...........       0.052 \b\  0.068...................  (no limit)..........           0.090       1,200 \c\
Dioxin, furans, TEQ (ng/dscm)....  0.41.................        0.13 \c\  0.011...................  0.002 \d\...........          0.0030              31
NOX (ppmv).......................  388..................              23  290\c\ (biomass units)/   76..................             200              78
                                                                           340 (coal units).
SO2 (ppmv).......................  20...................          11 \c\  6.2 \c\ (biomass units)/  720.................              38             1.2
                                                                           650 (coal units).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ All emission limits are measured at 7 percent oxygen.
\b\ See the memorandum ``CISWI Emission Limit Calculations for Existing and New Sources'' for details on this calculation.
\c\ The NSPS limit equals the EG limit. The EG limit was selected as the NSPS limit.
\d\ Dioxin/furan TEQ and Hg limits for ERUs--liquid/gas were replaced with D/F TEQ limits for liquid fuel major source boilers. See ``CISWI Emission
  Limit Calculations for Existing and New Sources'' for details.
\e\ Hg limit was developed using material input data from CISWI kilns identified within the Portland Cement NESHAP database. See the memorandum ``CISWI
  Emission Limit Calculations for Existing and New Sources'' for details on this calculation.

C. What are the testing and monitoring requirements?

    This final rule requires all CISWI units to demonstrate initial
compliance with the revised emission limits. For existing CISWI units,
these amendments require annual inspections of scrubbers, FF, and other
air pollution control devices that are used to meet the emission
limits. In addition, a Method 22 (40 CFR part 60, appendix A-7) visible
emissions test of the ash handling operations is required during the
annual compliance test for all subcategories except waste-burning
kilns, which do not have ash handling systems. Furthermore, for any
existing CISWI unit that operates a FF air pollution control device, we
are requiring that a bag leak detection system be installed to monitor
the device. These amendments continue to require parametric monitoring
of all other add-on air pollution control devices, such as wet
scrubbers and ACI. Commercial and industrial solid waste incineration
units that install SNCR technology to reduce NOX emissions
are required to monitor the reagent (e.g., ammonia or urea) injection
rate and secondary chamber temperature (if applicable to the CISWI
unit).
    This final rule also requires subcategory-specific monitoring
requirements in addition to the aforementioned inspection, bag leak
detection, and parametric monitoring requirements that are applicable
to all CISWI units. Existing incinerators, small, remote incinerators,
and ERUs would have annual emissions testing for all nine pollutants:
PM, SO2, HCl, NOX, CO, lead, Cd, Hg, and dioxins
and furans. Existing kilns are required to monitor Hg, PM, and HCl (if
no wet scrubber) emissions using a CEMS and perform annual testing for
the remaining pollutants. These amendments provide reduced annual
testing requirements for all nine pollutants when testing results are
shown to be well below the limits. If the ERU has a design capacity
less than or equal to 250 mmBtu/hr and is not equipped with a wet
scrubber control device, then a continuous opacity monitor is required
or, as an alternative, a PM CEMS could be employed (see below). If the
ERU has a design capacity greater than 250 mmBtu/hr, then PM emissions
must be monitored using a PM CEMS.
    For new CISWI units, the final rule requires the same monitoring

requirements as for existing units, but also requires CO CEMS for all
subcategories. Additionally, SO2 and NOX CEMS are
required for all new kilns.
    For all subcategories of existing CISWI units, use of CO CEMS is an
approved alternative and specific language with requirements for CO
CEMS is included in these amendments. For new and existing CISWI units,
use of PM, NOX, SO2, HCl, multi-metals and Hg
CEMS and integrated sorbent trap Hg monitoring and dioxin monitoring
(continuous sampling with periodic sample analysis) also are approved
alternatives, and specific language for those alternatives is included
in these amendments.

D. What are the requirements during periods of SSM?

    The 2000 CISWI standards did not apply during periods of SSM. This
final rule revises the 2000 CISWI rule such that the standards apply at
all times, including during SSM periods. As further explained in
section V.H of this preamble, the revision is being made in light of
the Court decision that vacated portions of regulations related to SSM
in the General Provisions of 40 CFR part 63. EPA is including in this
final rule an affirmative defense to civil penalties for exceedances of
emission limits that are caused by malfunctions. The full rationale for
these decisions is presented in section V.H of this preamble.

E. How do the rule amendments affect the applicability of the 2000 NSPS
and EG?

    Incinerators subject to the 2000 CISWI standards are treated
differently under the amended standards than they were under the 2000
CISWI rule in terms of whether they are ``existing'' or ``new''
sources.\2\ Consistent with the CAA section 129 definition of ``new''
sources, there are new dates defining what units are ``new'' sources.
Incinerators that are currently subject to the NSPS will become
``existing'' sources under the final amended standards and are required
to meet the revised EG by the applicable compliance date for the
revised guidelines. Those units will continue to be NSPS units subject
to the 2000 CISWI rule until they become ``existing'' sources under the
amended standards. Incinerators and small remote incinerators that are
existing sources under the 2000 EG must continue to comply with those
standards until the applicable compliance date for the revised EG, at
which time those sources must be in compliance with the applicable EG.
---------------------------------------------------------------------------

    \2\ We believe that all the units in the small remote
incinerator subcategory as defined in this final rule qualified for
the exemption for MWC in the 2000 CISWI standards. See 40 CFR
60.2020(c)(2) and 60.2555(c)(2).
---------------------------------------------------------------------------

    Commercial and industrial solid waste incineration units in the
four subcategories for which we are issuing final standards in this
rule that commenced construction after June 4, 2010, or for which a
modification is commenced on or after 6 months after promulgation of
these final standards, are ``new'' units subject to more stringent NSPS
emission limits. Units for which construction or modification is
commenced prior to those dates would be existing units subject to the
EG, except that units in the incinerators and small remote incinerators
subcategories remain subject to the 2000 CISWI rule until the
compliance date of the CISWI EG as discussed below. Commercial and
industrial solid waste incineration units in the subcategories other
than the incinerator subcategory and small remote incinerator
subcategory (if a unit was not exempt) will not in any case be subject
to the standards in the 2000 CISWI rule.
    Under this final rule, incinerators that commenced construction
after November 30, 1999, and on or before June 4, 2010, or that were
reconstructed or modified prior to the date 6 months after promulgation
of any revised final standards, are subject to the 2000 CISWI NSPS
until the applicable compliance date for the revised EG, at which time
those units would become ``existing'' sources. Similarly, units in the
incinerator or small remote incinerator subcategories that are subject
to the EG under the 2000 CISWI rule must meet the revised EG by the
applicable compliance date for the revised guidelines. Commercial and
industrial solid waste incineration units that commence construction
after June 4, 2010, or that are reconstructed or modified 6 months or
more after the date of promulgation of the revised standards, must meet
the revised NSPS emission limits in the NSPS within 6 months after the
promulgation date of the amendments or upon startup, whichever is
later.

F. What is the compliance schedule?

    New CISWI units must demonstrate compliance with the applicable
emission limit within 60 days after the CISWI unit reaches the charge
rate at which it will operate, but no later than 180 days after its
initial startup.
    Existing CISWI units must demonstrate compliance with the
applicable emission limits as expeditiously as practicable after
approval of a state plan, but no later than 3 years from the date of
approval of a state plan or 5 years after promulgation of these revised
standards, whichever is earlier.

G. What is the state plan implementation schedule?

    Under the final amendments to the EG, and consistent with CAA
section 129, revised state plans containing the revised existing source
emission limits and other requirements in the final amendments are due
within 1 year after promulgation of the amendments. States must submit
revised state plans to EPA March 21, 2012.
    These amendments to the EG allow existing CISWI to demonstrate
compliance with the amended standards as expeditiously as practicable
after approval of a state plan, but no later than 3 years from the date
of approval of a state plan or 5 years after promulgation of the
revised standards, whichever is earlier. Because we believe that many
CISWI units will find it necessary to retrofit existing emission
control equipment and/or install additional emission control equipment
in order to meet the final revised limits, EPA anticipates that states
may choose to provide the 3-year compliance period allowed by CAA
section 129(f)(2).
    In revising the standards in a state plan, a state has two options.
First, it may include both the 2000 CISWI standards and the new
standards in its revised state plan, which allows a phased approach in
applying the new limits. The state plan must make clear that the
standards in the 2000 CISWI rule remain in force for subject units and
apply until the date the revised existing source standards are
effective (as defined in the state plan).\3\ States where existing
CISWI incinerators do not need to improve their performance to meet the
revised standards, may want to consider a second approach as follows.
The state may replace the 2000 CISWI rule standards with the standards
in this final rule; follow the procedures in 40 CFR part 60, subpart B;
and submit a revised state plan to EPA for approval. If the revised
state plan contains only the revised standards (i.e., the 2000 CISWI
rule standards are not retained), then the revised standards must
become effective immediately for those units that are subject to the
2000 CISWI rule, since the 2000 CISWI rule

standards would be removed from the state plan.
---------------------------------------------------------------------------

    \3\ All sources currently subject to the 2000 CISWI EG or NSPS
will become existing sources in the incinerator or small remote
incinerator subcategories once the final revised CISWI standards are
in place. See section III.F of this preamble.
---------------------------------------------------------------------------

    EPA will revise the existing federal plan to incorporate any
changes to existing source emission limits and other requirements that
EPA has promulgated. The federal plan applies to CISWI units in any
state without an approved state plan. The proposed amendments to the EG
would allow existing CISWI units subject to the federal plan up to 5
years after promulgation of the revised standards to demonstrate
compliance with the amended standards, as required by CAA section
129(b)(3).

H. What are the requirements for submission of emissions test results
to EPA?

    EPA must have performance test data and other compliance data to
conduct effective reviews of CAA section 112 and 129 standards, as well
as for many other purposes including compliance determinations,
emissions factor development, and annual emissions rate determinations.
In conducting these required reviews, EPA has found it ineffective and
time consuming not only for us but also for regulatory agencies and
source owners and operators to locate, collect, and submit emissions
test data because of varied locations for data storage and varied data
storage methods. One improvement that has occurred in recent years is
the availability of stack test reports in electronic format as a
replacement for cumbersome paper copies.
    In this final rule, EPA is taking steps to improve data
accessibility. Owners and operators of CISWI units are required to
submit to EPA an electronic copy of reports of certain performance
tests required under the CISWI EG and NSPS. Sources must submit data
through the ERT. The ERT was developed with input from stack testing
companies who generally collect and compile performance test data
electronically and offices within state and local agencies which
perform field test assessments. The ERT is currently available, and
access to direct data submittal to EPA's electronic emissions database
(WebFIRE) is scheduled to become available by December 31, 2011.
    The requirement to submit source test data electronically to EPA
will not require any additional performance testing and will apply to
those performance tests conducted using test methods that are supported
by ERT. The ERT contains a specific electronic data entry form for most
of the commonly used EPA reference methods. The Web site listed below
contains a listing of the pollutants and test methods supported by ERT.
In addition, when a facility submits performance test data to WebFIRE,
there would be no additional requirements for emissions test data
compilation. Moreover, EPA believes industry will benefit from
development of improved emissions factors, fewer follow-up information
requests, and better regulation development as discussed below. The
information to be reported is already required for the existing test
methods and is necessary to evaluate the conformance to the test
method.
    One major advantage of collecting source test data through the ERT
is that it provides a standardized method to compile and store much of
the documentation required to be reported by this final rule while
clearly stating what testing information EPA requires. Another
important benefit of submitting these data to EPA at the time the
source test is conducted is that it substantially reduces the effort
involved in data collection activities in the future. Specifically,
because EPA would already have adequate source category data to conduct
residual risk assessments or technology reviews, there would likely be
fewer or less substantial data collection requests (e.g., CAA section
114 letters). This results in a reduced burden on both affected
facilities (in terms of reduced labor to respond to data collection
requests) and EPA (in terms of preparing and distributing data
collection requests).
    State/local/tribal agencies may also benefit in that their review
may be more streamlined and accurate because the states would not have
to re-enter the data to assess the calculations and verify the data
entry. Finally, another benefit of submitting these data to WebFIRE
electronically is that these data would improve greatly the overall
quality of the existing and new emissions factors by supplementing the
pool of emissions test data upon which the emissions factor is based
and by ensuring that data are more representative of current industry
operational procedures. A common complaint EPA receives from industry
and regulators is that emissions factors are outdated or not
representative of a particular source category. Receiving and
incorporating data for most performance tests would ensure that
emissions factors, when updated, represent accurately the most current
operational practices. In summary, receiving test data already
collected for other purposes and using them in the emissions factors
development program would save industry, state/local/tribal agencies,
and EPA, time and money and work to improve the quality of emissions
inventories and related regulatory decisions.
    As mentioned earlier, the electronic database that would be used is
EPA's WebFIRE, which is a database accessible through EPA's TTN (see
http://cfpub.epa.gov/webfire/). The WebFIRE database was constructed to
store emissions test and other data for use in developing emissions
factors. A description of the WebFIRE database can be found at http://cfpub.epa.gov/oarweb/index.cfm?action=fire.main.
    Source owners and operators will be able to transmit data collected
via the ERT through EPA's CDX network for storage in the WebFIRE
database. Although ERT is not the only electronic interface that can be
used to submit source test data to the CDX for entry into WebFIRE, it
makes submittal of data very straightforward and easy. A description of
the ERT can be found at http://www.epa.gov/ttn/chief/ert/ert_tool.html.
    Source owners and operators must register with the CDX system to
obtain a user name and password before being able to submit data to the
CDX. The CDX registration page can be found at https://cdx.epa.gov/SSL/CDX/regwarning.asp?Referer=registration. If they have a current CDX
account (e.g., they submit reports for the EPA's TRI Program to the
CDX), then the existing user name and password can be used to log in to
the CDX.

I. What are the costs and benefits of this final rule?

    EPA estimated the costs and benefits associated with the final
rule, and the results are shown in the following table. For more
information on the costs and benefits for this rule, see the Regulatory
Impact Analysis (RIA) in the EPA-HQ-OAR-2003-0119.

   Table 3--Summary of the Monetized Benefits, Social Costs, and Net Benefits for the CISWI NSPS and Emissions
                                               Guidelines in 2015
                                             [Millions of 2008$] a d
----------------------------------------------------------------------------------------------------------------
                                                  3% Discount rate                    7% Discount rate
----------------------------------------------------------------------------------------------------------------
Option 1: MACT Floor:
    Total Monetized Benefits \b\........  $340 to $830...................  $310 to $750.
    Total Social Costs \c\;.............  $280...........................  $280.
    Net Benefits........................  $60 to $550....................  $30 to $470.
    Non-monetized Benefits..............  25,000 tons of CO.
                                          470 tons of HCl.
                                          260 pounds of Hg.
                                          0.95 tons of Cd.
                                          4.1 tons of lead.
                                          92 grams of dioxins/furans.
                                          Health effects from NO2 and SO2
                                           exposure.
                                          Ecosystem effects.
                                          Visibility impairment.
Option 2: Beyond-the-Floor:
    Total Monetized Benefits \b\........  $430 to $1,100.................  $390 to $960.
    Total Social Costs \c\..............  $300...........................  $300.
    Net Benefits........................  $130 to $770...................  $90 to $660.
    Non-monetized Benefits..............  25,000 tons of CO.
                                          470 tons of HCl.
                                          260 pounds of Hg.
                                          0.95 tons of Cd.
                                          4.1 tons of lead.
                                          92 grams of dioxins/furans.
                                          Health effects from NO2 and SO2
                                           exposure.
                                          Ecosystem effects.
                                          Visibility impairment.
----------------------------------------------------------------------------------------------------------------
\a\ All estimates are for the implementation year (2015), and are rounded to two significant figures. These
  results include units anticipated to come online and the lowest cost disposal assumption.
\b\ The total monetized benefits reflect the human health benefits associated with reducing exposure to PM2.5
  through reductions of directly emitted PM2.5 and PM2.5 precursors such as NOX and SO2. It is important to note
  that the monetized benefits include many but not all health effects associated with PM2.5 exposure. Benefits
  are shown as a range from Pope, et al. (2002) to Laden, et al. (2006). These models assume that all fine
  particles, regardless of their chemical composition, are equally potent in causing premature mortality because
  there is no clear scientific evidence that would support the development of differential effects estimates by
  particle type. These estimates include energy disbenefits valued at $3.8 million.
\c\ The methodology used to estimate social costs for 1 year in the multimarket model using surplus changes
  results in the same social costs for both discount rates.
\d\ The estimates in this table reflect the estimates in the RIA. Due to last minute changes, we were unable to
  incorporate the final engineering costs and emission reductions into the RIA, which would decrease the costs
  by approximately 22% and increase the monetized benefits by approximately 4% from those shown here.

IV. Summary of Significant Changes Since Proposal

    EPA received over 3,500 public comments on the proposed rulemaking.
Furthermore, we conducted three public hearings to allow the public to
comment on the proposed rulemaking and the inter-related Boiler and
RCRA rules. Following are the major changes to the rule since the
proposal. The rationale for these and any other significant changes can
be found in section V of this preamble or in the document titled
``Commercial and Industrial Solid Waste Incineration (CISWI) Rule:
EPA's Response to Public Comments'' available in the docket for this
rulemaking.
     Clarified and revised the applicability and compliance
requirements for CISWI units that cease or begin combusting solid
waste.
     Determined that this final action will not subject burn-
off ovens, soil treatment units, cyclonic burn barrels, laboratory
analysis units, and space heaters to this standard.
     Further subcategorized ERUs with separate limits for
NOX, CO, and SO2 for coal and biomass units.
     Revised the definition of small, remote incinerators.
     Incorporated new data submitted by facilities since
December 15, 2010.
     Revised the emission limit methodology to use the UPL for
ERUs and waste-burning kilns.
     Revised the statistical analysis to use the log normal
distribution of data in cases where a normal data distribution is not
indicated conclusively by normality tests for the data.
     Revised the nondetect methodology to calculate emission
limits using three times the reported nondetect values where the value
equal to three times the representative MDL was greater than the
calculated MACT floor emission limit.
     Revised the requirements for opacity.
     Revised the monitoring requirements for continuous
compliance via testing and parametric monitoring and to allow CEMS use
to demonstrate compliance over a 30-day rolling average as an
alternative.
     Revised the CO CEMS monitoring requirement from mandatory
to voluntary for existing ERUs.
     Incorporated hourly CEMS data into emissions limit
calculations and 24-hour CEMS data into costing and impacts analyses.
     Revised the calculation methodology of D/F TEQ and
clarified that sources must comply with either the TMB or TEQ basis
limit.
     Added tire certification procedures for all CISWI units to
allow them to certify that the tires are from a program that enables
them to be considered non-waste materials.
     Added recordkeeping and reporting requirements for units
that burn materials other than traditional fuels.

     Revised the annual performance testing requirements to
clarify the schedule for completion of subsequent performance tests.
     Revised the reduced testing provision to state testing for
a given pollutant may be performed every 3 years, instead of annually,
if measured emissions during two consecutive annual performance tests
are less than 75 percent of the applicable emission limit.
     Revised the test methods for cement kilns to require EPA
Method 321 for HCl testing of these units.
     Removed the allowance for sources to use the results of
previously conducted tests to demonstrate compliance.
     Revised monitoring requirements for the waste-burning
kilns subcategory.
     Provided an affirmative defense to civil penalties for
exceedances of emission limits that are caused by malfunctions.

V. Public Comments

A. Legal and Applicability Issues, Compliance Schedule, and
Certification Procedures

1. Section 129 vs. Section 112--Applicability for Waste Firing Boilers
and Kilns That Opt To Stop Burning Waste
    Comment: Many commenters stated that ERUs and waste-burning kilns
should be able to move between CAA sections 129 and 112 standards based
on the materials being burned. Commenters argued that EPA should
provide flexibility for operators of units burning co-fired waste to
consider the stringency of all applicable standards and opt into the
appropriate rule. Many commenters contended that requiring operators
who stop burning solid waste to remain regulated under CISWI would
penalize them with no benefit gained. One commenter stated that no law
or regulation prevents EPA from allowing a unit to opt out of CISWI and
that the concern that facilities would ``backslide'' from MACT control
levels is not applicable. Further, commenters argued that the once-in-
always-in policy should not apply to CISWI and requested clarification
on how the policy applies to sources subject to CAA section 129
standards that either continue or begin combusting solid waste. One
commenter requested that EPA clarify whether the CISWI rule would apply
to any kiln that is actually using solid waste or to any kiln
authorized to do so.
    Response: This rule addresses the combustion of solid waste
materials (as defined by the Administrator under RCRA) in combustion
units at commercial and industrial facilities. If an owner or operator
of a CISWI unit permanently ceases combusting solid waste, the affected
unit is no longer subject to this regulation under CAA section 129, and
the unit would become subject to any applicable regulations under CAA
section 112. Likewise, if an owner or operator of any commercial or
industrial unit starts combusting solid waste in that unit, it becomes
subject to CISWI, and is no longer subject to any previously applicable
regulations under section 112. Consistent with CAA section 129(h)(2),
no solid waste incineration unit subject to performance standards under
section 129 and section 111 shall be subject to standards under section
112(d) of the Act.
    CISWI units that cease burning solid waste in the ERU and waste-
burning kiln subcategories may be subject to one of three rulemaking
actions under CAA section 112. EPA is finalizing in a parallel action
two NESHAP applicable to boilers, one for area source boilers and one
for major source boilers that also regulates process heaters at major
sources. EPA also recently finalized revised NESHAP for cement kilns
(74 FR 54970, September 9, 2010). Energy recovery units and waste-
burning kilns subject to CISWI that cease burning solid waste, and thus
cease being subject to this final rule, will be subject to the NESHAP
for area source boilers, major source boilers and process heaters, or
cement kilns, as appropriate.
    Today's final rule includes provisions to address the situation
where CISWI units cease burning solid waste, and where existing
commercial and industrial facilities start burning solid waste. Units
that cease burning solid waste remain subject to CISWI for at least 6
months after solid waste is no longer present in the combustion
chamber. After 6 months, sources must either comply with any applicable
section 112 standards or, if they intend to combust solid waste in the
unit in the future, opt to remain subject to CISWI. Sources switching
out of CISWI due to cessation of solid waste combustion must submit
advance notification of the effective date of the waste-to-fuel switch
consistent with new procedures in this rule. Units that begin
combusting solid waste are considered existing sources under CISWI and
must comply with the emissions guidelines set forth in the CISWI final
rule at the time they begin burning solid waste.
    EPA acknowledges that sources may stop and start burning solid
waste in their combustion units, and that regulatory procedures are
necessary to guide sources through the changes in applicability that
may result due to a switch in combustion materials. New provisions in
the final rule account for the fact that facilities may start and stop
burning solid waste and ensure that any resulting changes in
applicability between section 129 and section 112 rules do not occur
with so much frequency that sources are unable to demonstrate
continuing compliance with the applicable standards.
    To ensure that frequent switching does not impede our ability to
determine continuous compliance and create undue permitting and testing
burdens, sources remain subject to CISWI for a minimum of 6 months. The
definition of CISWI unit has been revised to clarify that a CISWI unit
includes a distinct operating unit of any commercial or industrial
facility that combusts any solid waste in a 12-month period. This
change accounts for sources that periodically burn solid waste
throughout a given 12-month period, but that also has long periods in
which no solid waste is combusted at all. We believe this change will
reduce administrative and compliance costs to both the source and the
regulatory agencies. For example, sources will not have to re-establish
initial compliance with CISWI or revise their operating permit to
reflect a switch out of and back into the CISWI regulations. Instead,
facilities that combust solid waste would continue to be subject to the
CISWI regulations at least 6 months after waste is no longer combusted.
The regulations also allow facilities to remain subject to CISWI beyond
6 months after cessation of solid waste combustion, at their own
discretion, if the source determined that continued compliance with
CISWI is appropriate because the source intends to combust solid waste
in the future. Source owners or operators may, alternatively, choose a
date at least 6 months after ceasing solid waste combustion on which
they would no longer be subject to CISWI, and would instead be subject
to any applicable section 112 standards. This date is called the
effective date of the waste-to-fuel switch.
    Specifically, the new provisions direct a source owner or operator
to select an effective date for the waste-to-fuel, or fuel-to-waste
switch, and that date becomes the date on which all of the newly
applicable requirements apply. When a source begins combusting solid
waste, the effective date of the fuel-to-waste switch must be the same
as the actual date the unit begins combusting solid waste because by
statute any source that combusts any solid waste is a solid waste
incineration unit subject to standards under CAA section 129. See
section 129(g)(1)

(defining ``solid waste incineration unit''). For sources that cease
burning solid waste, they may pick an effective date for the waste-to-
fuel switch that is at least 6 months after the last date on which
solid waste is combusted. This allows sources that cease combusting
solid waste to comply with an applicable NESHAP or opt to remain
subject to CISWI at the discretion of the owner or operator. We allow
the owner or operator of a CISWI unit the option of remaining subject
to CISWI to account for sources that may want to retain the ability to
burn waste intermittently without having to periodically switch between
the section 112 and section 129 regulatory programs. If a source wishes
to end applicability of CISWI to its unit, the source must submit an
advance notification of the effective date of the waste-to-fuel switch.
The source must be in compliance with any NESHAP that applies as a
result of ceasing the combustion of solid waste on the effective date
of the waste-to-fuel switch. The source must remain in continuous
compliance with the CISWI regulations until that date.
    As stated above, boiler and process heaters that commence
combustion of any solid waste and become solid waste incineration units
as defined in section 129(g)(1) are subject to CISWI standards
applicable to ERUs as of the date they commence combusting solid waste.
Likewise, cement kilns that begin combusting solid waste and become
solid waste incineration units must comply with the CISWI standards
applicable to waste-burning kilns at the time they begin combusting
solid waste.
    The new waste-to-fuel switch provisions in the final rule include
requirements to conduct performance testing that will assure compliance
with all applicable standards. Specifically, performance tests must be
conducted within 60 days of the date on which the unit begins
combusting solid waste. In addition, the owner or operator must collect
and report any PM CEMS and/or PM parametric monitoring data for those
monitors that are operated at the same time as the performance test to
determine whether the existing calibrations and/or correlations are
still applicable. After the testing is completed, and it is
demonstrated that the source is operating in compliance with the
applicable standards, the owner or operator should adjust any PM CEMS
calibration and any correlation for PM to correspond to the performance
test results and data.
    The new provisions also require advance notification of the
effective date of the waste-to-fuel switch. The notification includes
basic information that will enable the reviewing authority to determine
the date on which CISWI will no longer apply to the facility and the
date on which any newly applicable section 112 regulations may apply.
Notification must be submitted to both the EPA Regional Office and the
delegated state or local agency.
    To ensure that frequent switching does not impede our ability to
determine continuous compliance, sources may not switch between
applicable section 129 and section 112 standards without completing the
initial performance test. Therefore, sources that wish to start burning
solid waste before they have demonstrated compliance with their
existing section 112 standard must complete the performance test for
the 112 rule before switching to solid waste combustion.
    If a source switches back to a fuel or non-waste material for which
a performance test was conducted within the 6 months preceding the
effective date of the fuel-to-waste or waste-to-fuel switch, and if
there are no changed conditions that would affect emissions, the source
need not retest that source until 6 months from the effective date of
the switch.
    If a source is subject to any emissions limits for which compliance
is determined on an annual average or other averaging period that is
for a period of time less than the period in which the source will be
combusting the fuel or non-waste material, the source must comply with
the emission limit in the shorter time period in which the fuel or
material is combusted. For example, if a source chooses to demonstrate
compliance with the Hg limits of the major source Boiler NESHAP through
fuel analysis, which has a 12-month rolling average limit, and opts to
start burning solid waste and become subject to CISWI after combusting
the fuel under the Boiler NESHAP for only 9 months, the source must
demonstrate compliance with the Hg limit based on a 9-month average
instead of the annual average. The EPA believes this is necessary to
assure that switching to solid waste combustion does not compromise our
ability to determine compliance with standards under section 112.
    The rules do not allow for compliance extensions associated with
changes to the fuels or materials that are combusted. After the first
substantive compliance date (e.g., the effective date of the state
program or 5 years after publication of the final CISWI rule for
incineration units), sources must be in compliance with the standard
that is applicable to the source based on the type of unit and the
fuels or materials that are combusted. Sources that change fuels or
materials are considered existing sources and, as such, they must be in
compliance on the date they begin combusting the new fuel or material.
For example, a waste-burning cement kiln that ceases burning solid
waste becomes subject to and must comply with the Portland Cement
NESHAP as of the date that it is no longer subject to CISWI. For all
sources that commence combustion of solid waste, the CISWI requirements
become applicable on the date that the fuel switch occurs.
2. Homogeneous Waste
    Comment: Many commenters requested that EPA reaffirm the exemption
of qualifying small power production and cogeneration facilities as
promulgated in the 2000 CISWI regulations. Several commenters requested
that EPA clarify the term ``homogeneous waste.'' Some commenters
requested that certain mixtures or blends of fuels fall under the
definition of homogeneous waste.
    Response: Homogeneous wastes are stable, consistent in formulation,
have known fuel properties, have a defined origin, have predictable
chemical and physical attributes, and result in consistent combustion
characteristics and have a consistent emissions profile. Qualifying
small power production and cogeneration facilities requesting an
exemption from CISWI on the basis that they burn homogeneous waste may
be asked to demonstrate, using defined test methods acceptable to EPA,
that the physical and chemical characteristics of the waste are
consistent throughout such that the emission profile of any sample of
waste combusted is similar or identical to any other sample. Mixtures
of different types of wastes are generally not homogeneous, unless the
mixtures are from materials that are each individually determined to be
homogeneous, are from known origin, are mixed in constant proportion,
and are conditioned or processed, such as would occur in the
gasification of the wastes. Gasification processes that incorporate
clean up technologies in the production of synthesis gas would
generally result in a homogeneous product, however a consistent waste
input would still be necessary to ensure a consistent emissions profile
of the synthesis gas. Whether a waste is homogeneous is a case-by-case
determination. As such, EPA has added provisions to the CISWI rule that
require source owners or operators seeking the exemption to submit a
request for a homogeneous fuel determination to EPA, and that they
support their request

with information describing the materials to be combusted and why they
believe the waste is homogeneous. The determination of what constitutes
a homogeneous waste is not delegable to the state or local agencies.
3. Lab Analysis Units
    Comment: Commenters stated that they do not believe CAA section 129
is intended to regulate laboratory analysis units that involve
combustion to generate analytical results. Commenters contend that
samples are not solid waste and have definite purpose separate from
disposal of sample material. They stated that it is physically
impossible for many, if not all, of these uses to comply with CISWI
requirements and therefore operations would likely cease. Several
commenters indicated that it is unclear as to whether the material
referenced in the existing definition of laboratory units in 40 CFR
60.2020(o) (subpart CCCC) and 40 CFR 60.2555(o) (subpart DDDD) is a
solid waste. Several commenters stated that other CISWI requirements
including operator certification, performance tests, and SSM
requirements are not appropriate for laboratory units. If regulated,
commenters requested that EPA clarify whether the rule is applicable to
all laboratory units or limited to those at commercial and industrial
facilities. Many argued that EPA underestimated the number of
laboratory units affected by this regulation because the Phase I ICR
was not clear that these units were included in the scope of the
survey. Commenters also stated that EPA did not provide cost or impact
analysis for these units.
    Response: EPA agrees that samples used in laboratory analysis units
have a purpose separate from the disposal of material, and we believe
based on the information available at this time, that the material that
is combusted is likely not a solid waste as that term is defined in the
Solid Waste Definition Rule. We have no information that refutes our
conclusions, and we have no data from laboratory analysis units on
which to establish section 129 standards in any case. We have
determined that this final action will not subject laboratory analysis
units to this standard.
4. Asphalt Recycling
    Comment: One commenter requested that EPA provide a clarification
as to whether asphalt plants utilizing recycled asphalt would be
subject to the CISWI rule.
    Response: EPA did not receive any information to indicate that
recycled asphalt is a solid waste, or that the recycled asphalt or
solid waste is being combusted in asphalt plants. Absent that
information, we are not establishing separate standards regulating
asphalt plants at this time. However, any combustion unit that combusts
solid waste and meets the definition of a CISWI unit may be subject to
the CISWI rule, including combustion units at asphalt plants. If the
combustion unit is recovering useful heat (e.g., process heaters and
boilers), the unit may be subject to standards applicable to ERUs and
sources should contact EPA or their state for a specific determination.
5. Chemical Recovery (SARUs)
    Comment: Several commenters suggested that EPA provide a clear
definition of a chemical recovery unit in the final rule. They
requested that EPA specifically define chemical recovery units burning
pulping liquors and kilns burning lime as not CISWI units.
    Commenters suggested that EPA include language that explicitly
states SARUs are not subject to CISWI citing the CAA exemption for
analogous processes. Some commenters argued that materials burned in
SARUs are not ``solid wastes'' because they are not burned for the
purpose of being disposed of or discarded. Instead, commenters asserted
that the primary purpose of SARUs is to combust materials to recover
sulfur in order to produce virgin sulfuric acid. A few commenters also
stated that SARUs are already regulated under 40 CFR part 60, subpart
H, Standards of Performance for Sulfuric Acid Plants.
    Response: The Solid Waste Definition Rule exempts materials
pursuant to subtitle C of RCRA. Any SARU, chemical recovery unit,
recovery furnace, or lime kiln that is exempt pursuant to subtitle C of
RCRA is not a CISWI unit subject to this final rule unless the unit
combusts material that is solid waste and is not specifically exempt
from the definition pursuant to subtitle C of RCRA. We are currently
not aware of any subtitle C exempt facilities burning such materials.
We are also not aware of any lime kilns that are combusting solid waste
as that term is defined in the Solid Waste Definition Rule. To the
extent there are lime kilns or chemical recovery units combusting solid
waste, those units may be subject to the final CISWI standards as
incinerators, ERUs, or waste-burning kilns, as appropriate. Units
discussed in this comment that are combusting solid waste should
consult EPA or their state concerning applicability of this final rule
to their combustion unit.
6. Exemptions--Hazardous Waste Combustion Units
    Comment: Several commenters urged EPA to retain the exemption for
hazardous waste combustion units or clarify that these units are not
subject to the proposed rule and do not need an exemption. Commenters
suggested that the removal of this exemption could shift certain RCRA
provisions from a RCRA permit to a Title V permit.
    Response: Hazardous waste combustion units that are required to
have a permit under section 3005 of the SWDA are exempt from CAA
section 129 rules per CAA section 129(g)(1). Thus, these hazardous
waste combustion units would not be subject to the CISWI requirements.
7. CISWI Promulgation Schedule and 112(c)(6) Obligations
    Comment: Many commenters requested that EPA delay issuing the CISWI
standard until the Solid Waste Definition Rule is finalized. They
argued that the court-ordered deadline does not apply to CISWI and that
the lack of certainty in the outcome of the Non-Hazardous Solid Waste
Definition Rule affects all aspects of the CISWI proposal including the
number of facilities affected, the MACT floors, and the total
anticipated compliance costs. Some commenters believe that this
violates EPA's duty to provide a full and fair opportunity to develop
and submit comments on the proposal. They contend that this problem can
only be addressed by promulgating the waste rule and then re-proposing
CISWI standards based on the known population of units.
    One commenter suggests that EPA's proposal to treat the proposed
CAA section 129 standards as satisfying CAA section 112(c)(6)
requirements is unlawful. They argue that EPA's statement that its
proposed CAA section 129 standards ``effectively control'' emissions of
POM and PCBs, identified in CAA section 112(c)(6) as pollutants for
which EPA must regulate 90 percent of aggregate emissions under CAA
sections 112(d)(2) or 112(d)(4), is illegal. The commenter asserts that
the CAA requires EPA to subject 90 percent of the emissions of the
pollutants identified in CAA section 112(c)(6), including POM and PCBs,
to CAA section 112(d)(2) or (d)(4) standards. The commenter argues that
assuming EPA could meet CAA section 112(c)(6) requirements by taking
credit for standards established under CAA section 129, EPA would have
to set specific CAA section 129 standards for POM and PCBs. They
suggest that although CAA section 129(a)(4) gives

EPA authority to do just that, EPA has not proposed CAA section 129
standards for POM or PCBs. The commenter believes that the proposed
CISWI standards would not satisfy CAA section 112(c)(6) even if CAA
section 129 standards could do so. The commenter states that EPA cannot
meet its obligations to regulate PCBs and POM under CAA section
112(c)(6) with the proposed CAA section 129 standards for other
pollutants. Another commenter claims that they cannot find
documentation in the proposed rulemaking package to explain how and why
coverage of CISWI sources is necessary to meet the 90 percent
requirement.
    Response: EPA disagrees with the commenters who suggest the Court-
ordered deadline does not apply to certain CISWI units. The EPA
maintains that we are under a Court-ordered deadline to complete our
CAA section 112(c)(6) obligations by January 16, 2011. Because we need
certain CISWI units to comply with our 112(c)(6) obligations, the
Court-ordered deadline requires EPA to promulgate the CISWI standards
for certain subcategories by January 16, 2010. The EPA may therefore
not postpone issuance of the final CISWI rules until after the Solid
Waste Definition Rule is promulgated.
    Section 112(c)(6) of the CAA requires EPA to regulate sources
accounting for not less than 90 percent of the aggregate emissions of
each pollutant listed in CAA section 112(c)(6). EPA has historically
interpreted CAA section 112(c)(6) as allowing EPA to count CAA section
129 emission standards, such as CISWI, for the purpose of meeting its
90 percent obligation under CAA section 112(c)(6) (62 FR 33625, 33632,
June 20, 1997). For example, both municipal waste combustion units and
medical waste incinerators are listed CAA section 112(c)(6) source
categories, and they are regulated under CAA section 129.
    As EPA stated in 1998, we need to issue emissions standards for all
Portland Cement kilns that combust non-hazardous waste (both major and
area sources) to meet our obligation under CAA section 112(c)(6) (63 FR
17838, 17849, April 10, 1998). In addition, EPA must issue standards
for commercial and institutional combustion units (e.g., boilers and
process heaters) to comply with the section 112(c)(6) obligation (63 FR
32006, June 4, 2010). We must set standards for all CAA section
112(c)(6) categories by the Court-ordered deadline, and that includes
setting emission standards pursuant to CAA section 129 for those
Portland Cement kilns and commercial and institutional boilers and
process heaters that combust non-hazardous solid waste and are thus
subject to CISWI as waste-burning kilns and ERUs, respectively.
    As we stated in section VI of the proposed rule, section 112(c)(6)
of the CAA requires EPA to identify categories of sources of seven
specified pollutants to assure that sources accounting for not less
than 90 percent of the aggregate emissions of each such pollutant are
subject to standards under CAA section 112(d)(2) or 112(d)(4). EPA has
identified certain CISWI units as sources necessary to meet the 90
percent requirement under section 112(c)(6). In the Federal Register
notice ``Source Category Listing for Section 112(d)(2) Rulemaking
Pursuant to Section 112(c)(6) Requirements,'' 63 FR 17838, 17849, Table
2 (1998), EPA identified source categories that must be ``subject to
regulation'' for purposes of CAA section 112(c)(6). Included in that
list are cement kilns and combustion units (e.g., major source boilers
and process heaters). Cement kilns, boilers, and process heaters that
combust solid waste are subject to the CAA section 129 standards for
CISWI as either waste-burning kilns or ERUs. These CISWI units emit
five of the seven CAA section 112(c)(6) pollutants: POM, dioxins,
furans, Hg and PCBs. The POM emitted by CISWI is composed of 7-PAH, 16-
PAH, and EOM.
    For purposes of CAA section 112(c)(6), EPA has determined that
standards promulgated under CAA section 129 are substantively
equivalent to those promulgated under CAA section 112(d). (63 FR 17845;
62 FR 33625, 33632 (1997)). As discussed in more detail in response to
comments on this issue, the CAA section 129 standards effectively
control emissions of the five identified CAA section 112(c)(6)
pollutants. Further, since CAA section 129(h)(2) precludes EPA from
regulating CISWI units under CAA section 112(d), EPA cannot further
regulate the emissions of 112(c)(6) pollutants from CISWI units under
CAA section 112(d). As a result, EPA considers emissions of these five
pollutants from waste-burning kilns and ERUs ``subject to standards''
for purposes of CAA section 112(c)(6). The remaining CISWI
subcategories will be subject to MACT standards either in this action
or in a future action, but regulation of the remaining subcategories is
not required for EPA to complete its 112(c)(6) obligations.
    As required by the statute, the CAA section 129 CISWI standards
include numeric emission limitations for the nine pollutants specified
in CAA section 129(a)(4). The combination of waste segregation, good
combustion practices, and add-on air pollution control equipment
(sorbent injection, FF, wet scrubbers, or combinations thereof)
effectively reduces emissions of the pollutants for which emission
limits are required under CAA section 129: Hg, dioxins, furans, Cd, Pb,
PM, SO2, HCl, CO, and NOX. Thus, the standards
specifically require reduction in emissions of three of the CAA section
112(c)(6) pollutants: dioxins, furans, and Hg. As explained below, the
air pollution controls necessary to comply with the requirements of the
CISWI standards also effectively reduce emissions of the following CAA
section 112(c)(6) pollutants that are emitted from waste-burning kilns
and ERUs: POM and PCBs. Although the CAA section 129 CISWI standards do
not have separate, specific emissions standards for POM and PCBs,
emissions of these two CAA section 112(c)(6) pollutants are effectively
controlled by the same control measures used to comply with the
numerical emissions limits for the pollutants enumerated in CAA section
129(a)(4). Specifically, as by-products of combustion, the formation of
POM and PCBs is effectively reduced by the combustion and post-
combustion practices required to comply with the CAA section 129
standards, primarily the standards for CO and D/F. In fact, EPA has
used CO as a surrogate for organic HAP such as POM, and the controls
for PCBs are the same controls that reduce emissions of dioxin and
furans. Polycyclic Organic Matter and PCBs that do form during
combustion are further controlled by the various post-combustion CISWI
controls. The add-on PM control systems (either FF or wet scrubber) and
ACI further reduce emissions of these organic pollutants and also
reduce Hg emissions, as is evidenced by performance data for MWCs and
another similar source category, HMIWI. Specifically, the post-MACT
compliance tests at currently operating HMIWI that were also
operational at the time of promulgation of the 1997 HMIWI MACT
standards show that, for those units, the regulations reduced Hg
emissions by about 60 percent and reduced dioxin and furans emissions
by about 80 percent from pre-MACT levels. Dioxin and furans have
similar chemical composition and structure as PCBs and POM; moreover,
similar controls have been demonstrated to reduce emissions of D/F,
POM, and PCBs from MWCs. It is reasonable to conclude that POM and PCB
emissions would be effectively controlled to a MACT level at all CISWI

units meeting the emission limits for the section 129 pollutants. Thus,
while the rule does not identify specific numerical limits for POM and
PCB, emissions of those pollutants are, for the reasons noted above,
nonetheless ``subject to regulation'' for purposes of CAA section
112(c)(6).
    Finally, we disagree with comments that EPA should not finalize the
CISWI standards until after the Solid Waste Definition Rule is final
because EPA does not know the population of sources that will be
subject to the CISWI standards. As stated above, we must finalize the
CISWI standards for certain subcategories to comply with the Court-
ordered deadline; but, in any case, we would not postpone the standards
absent the deadline based on the commenters' issue. EPA must establish
standards for all rules based on the best information available at the
time of issuance. In this case, we have included those units that we
believe combust solid waste as that term is defined in the final Solid
Waste Definition Rule. We have no information at this time that allows
us to determine that the units we have included are not combusting
solid waste. Furthermore, sources in the waste-burning kilns and ERUs
subcategories and their CAA section 112 counterparts may start or stop
combusting solid waste at any time and thus move between CAA sections
112 and 129. Sources in any of the subcategories could also cease
operation all together. For these reasons, we conclude it is not
appropriate to postpone regulation in this case because we could never
be certain that the list of units we identify is perfect. We maintain
that the approach we have taken is reasonable because it is based on
the best information available to EPA at the time of promulgation.
8. CISWI Implementation Schedule
    Comment: Several commenters suggested that the date for compliance
should be set at 5 or 6 years, not 3 years. Several commenters raised
concern that many facilities may not have sufficient time to engineer
and design the emissions control systems, raise the amount of capital
to purchase the equipment, and install the required equipment. In
addition, there could be hardware backlogs, insufficient skilled labor,
and gridlock in state permitting processes which could delay
compliance. Further commenters stated that they need time to plan a
shutdown of a unit when everything is properly staged to ensure minimal
disruption of the facility's operation.
    Response: The terms of CAA section 129(b)(2), where state plan
implementation schedules are specified, outline the maximum time
available for implementation and enforcement of EG for solid waste
incineration units. As CAA section 129(b)(2) states, the state plan ``*
* * shall provide that each unit subject to the guidelines shall be in
compliance with all requirements of this section not later than 3 years
after the state plan is approved by the Administrator but not later
than 5 years after the guidelines were promulgated.'' This allows 2
years for state plans to be updated, modified, and approved by the
Administrator, followed by a period of compliance not to exceed 3 years
after the state plan has been approved.

B. MACT Floor Analysis

1. Pollutant-by-Pollutant Approach and Alternative Approaches
    Comment: Many commenters objected to setting MACT floors on a
pollutant-by-pollutant basis. They argue that setting MACT floors on a
pollutant-by-pollutant basis is unlawful and results in MACT floors
that bear no relation to emission limits that are being achieved at the
best-performing existing sources pursuant to CAA section 129(a)(2). The
commenters suggested that EPA has misinterpreted many court cases
involving CAA section 112(d) over the years and that the proposed MACT
standards are inconsistent with the legal principles established under
previous court decisions because emission standards must be ``achieved
in practice'' before finalizing the regulation. Commenters continued by
explaining that EPA applies the ``achieved in practice'' standard on a
pollutant-by-pollutant basis, which results in a final standard that
they assert has never been achieved by any subject facility or best
performer. Some commenters contended that this method violates the
plain language and intent of the MACT process, and the result is a MACT
floor that reflects a standard that no one plant in existence currently
achieves. The commenters declared that the plain language of MACT
process requires EPA to set a MACT floor for existing sources that is
not less stringent than ``the average emission limitation achieved by
the best-performing 12 percent of units in the category.'' The
commenters asserted that CAA sections 129(a)(2) and 112(d) use of the
terms ``best-performing'' and ``existing'' clearly means that sources
in a category or subcategory that are used to set the MACT floor are to
be real, not theoretical or hypothetical sources. Some commenters
maintained that CAA section 129(a)(2) instructs that the MACT floor
``shall not be less stringent than the emission control that is
achieved in practice by the best controlled similar source'' and the
phrase ``achieved in practice'' can only mean that Congress intended
actual sources, performing under real-life conditions, to be the
benchmark for determining the MACT floors. The commenters stated that
in the CISWI rulemaking, EPA has chosen to establish the MACT floor by
assessing the best-performing sources on a pollutant-by-pollutant
basis, rather than by identifying the overall best-performing sources
taking into account all pollutants.
    Some commenters insisted that if Congress wanted EPA to establish
separate MACT floor levels for different pollutants, it would have
worded CAA section 129(a)(2) to allow this result by referring to the
best-performing sources ``for each pollutant'' or ``for each group of
pollutants.'' Further, they argued that EPA's pollutant-by-pollutant
methodology is at odds with the legislative history underlying the MACT
setting process. The commenters cited the Senate report on the 1990
Amendments where Congress required ``the selection of emissions
limitations which have been achieved in practice (rather than those
which are merely theoretical) by sources of a similar type or
character. An emissions limitation achieved in practice is one based on
control technology that works reasonably well (doesn't require frequent
and extensive modification or repair) under realistic operating
conditions.'' See S. Rep. No. 228, 101st Cong., 1st Sess. 169 (1989).
The commenters suggested that the focus on overall performance is not
surprising because in the 1990 CAA Amendments, Congress abandoned the
previous focus on individual pollutant standards, and adopted the
technology-based multi-pollutant approach to regulating emissions in
use under the CWA. A few commenters suggested that if one source can
achieve a firm degree of control for one pollutant but not for another,
there may be no justification for including it in the set of sources
from which the floor is calculated.
    Several commenters recommended that EPA develop overall rankings
for each unit in each subcategory based on their emissions of all nine
pollutants and develop floors based on a common set of top performers.
The commenters asserted that this approach would identify the overall
best-performing sources taking into account all pollutants. The
commenters argued that the statute unambiguously directs EPA to set
standards based on the overall performance of ``units.'' They

maintained that CAA section 129(a)(2) specifies that emissions
standards must be established based on the performance of ``units'' in
the category or subcategory, and that EPA's discretion in setting
standards for such units is limited to distinguishing among classes,
types, and sizes of units. By setting floors based on the average of
the top performing 12 percent of units in a subcategory and also using
a confidence limit to attempt to account for variability, one would
assume that at least 6 percent of all units in each subcategory would
be able to comply with the emission limits with no further controls.
    Several commenters argued that while an individual MACT floor for
one pollutant might not appear cost-prohibitive, the total cost
implications when combined with all of the other MACT floors for other
pollutants, could become especially onerous, potentially forcing some
regulated parties out of business, and barring the market entry for
other potential entities. The commenters contended that this result is
compounded when the proposed emission limits cannot be met even after
the installation and proper operation of MACT hardware such as
scrubbers and baghouses. The commenters stated that some facilities
cannot operate certain types of control devices due to local
operational constraints and feed material composition. The commenters
declared that such a result violates the court's declaration in
National Lime Association 627 F.2d 416, 443 (DC Cir. 1980), that under
the CAA ``EPA has a statutory duty to promulgate achievable
standards.'' A few commenters insisted that while the CAA was authored
with the intent of reducing air pollution, Congress did not intend to
disrupt the ``productive capacity'' of the United States through the
promulgation of economically unachievable standards. 42 U.S.C.
7401(b)(1). The commenters maintained that by setting MACT floors
individually and ignoring the collective cost implications of the
entire rule, EPA would effectively disregard the CAA requirement that
air pollution control be advanced while promoting the nation's
``productive capacity.'' The commenters stated that emissions standards
are to be established by taking costs into consideration. 42 U.S.C.
7429(a)(2).
    One commenter discussed that EPA previously used a pollutant-by-
pollutant methodology to set MACT floors in the context of the Proposed
National Emissions Standards for Hazardous Waste Combustors (69 FR
21198, April 20, 2004), hereinafter referred to as the HWC NESHAP. The
commenter stated that several parties submitted public comments
questioning EPA's approach and pointed to the fact that EPA had failed
to cite a single existing source which met the various MACT floor
standards. They stated that EPA attempted to defend its practice of
establishing pollutant-by-pollutant MACT standards by citing the
Chemical Manufacturer Association v. EPA, 870 F.2d 177, 239 1989),
clarified 885 F.2d 253, 264 (5th Cir. 1989), cert. denied, 495 U.S.
910, (1990), a Fifth Circuit case where the court held that, under the
CWA, ``best available technology'' referred to the single best-
performing plant on a pollutant-by-pollutant basis. The commenter
asserts that EPA's reliance on Chemical Manufacturer Association v. EPA
is misplaced as the CAA's procedure regarding the selection of MACT
technologies differs on a textual basis from the CWA's procedure for
identifying BAT. The commenter argued that under the CWA, BAT standards
are to be set based on ``the best practicable control technology
currently available.'' The commenter suggested that the Court in
Chemical Manufacturer Association v. EPA read this provision to allow
for pollutant-by-pollutant determinations finding no statutory
requirement that all of the BATs actually be achieved by an existing
plant, just that each technology be demonstrated available. 885 F.2d at
264. The commenter continued that the CAA, on the other hand, more
narrowly limits the basis for MACT designation to what has been
achieved at existing sources, not what could be hypothetically
achievable on a per-pollutant basis.
    A few commenters also cited the HWC NESHAP as an example where EPA
attempted to support its use of the pollutant-by-pollutant methodology
by stating that ``EPA believes that because all our standards are not
technically interdependent (i.e., implementation of one emission
control technology does not prevent the source from implementing
another control technology), the fact that sources are not achieving
all the standards simultaneously does not indicate a flaw in the
methodology.'' The commenters argued that EPA's conclusion in the HWC
NESHAP is inapplicable to the proposed CISWI rule. They provided an
example problem that they claimed has been observed in the MSW industry
using ACI (an EPA-identified technology to reduce Hg emissions) and
could also occur in the cement industry could be the formation of
additional solid-phase dioxins/furans, thus increasing the emissions of
D/F (which are regulated under the MACT standards). The commenters
suggested that these findings call into question EPA's legal
justification that control requirements for one pollutant do not impact
another. Several commenters suggested that there is an inverse
relationship between CO and NOX where improving combustion
to control CO may affect NOX. Finally, many commenters
requested that EPA require work practice standards in lieu of emission
limits for certain ERUs.
    Response: We disagree with the commenters who object to setting
MACT floors on a pollutant-by-pollutant basis. Contrary to the
commenters' suggestion, CAA section 129(a)(2) does not mandate a total
facility approach. EPA previously has explained that although CAA
section 129 does not unambiguously declare that MACT floors must be
established on a pollutant-by-pollutant basis, applying the requirement
to set MACT floors based on what has been achieved by the best-
performing sources for each of the pollutants covered by CAA section
129 is a reasonable interpretation of EPA's obligation under that
provision (62 FR 48363-64).
    Commenters' primary argument is premised on a reading of two
clauses in CAA section 129(a)(2). Specifically, commenters cite the
provision of CAA section 129 that, for new sources, states that MACT
floors ``shall not be less stringent than the emission control that is
achieved in practice by the best controlled similar unit'' and, for
existing sources, states that MACT floors must be based on ``the
average emissions limitation achieved by the best-performing 12 percent
of units in the category.'' Commenters make the assumption that
``achieved in practice'' as applied to the best controlled ``similar
unit'' and ``best-performing 12 percent of units in the category'' must
be interpreted to mean the best-performing unit or units with respect
to the entire suite of pollutants.
    EPA makes no such assumption, primarily because to do so would lead
to the illogical result of basing emissions limitations on units that
may not be the best-performing source for any single covered pollutant.
Instead, EPA interprets the provision to support establishing emissions
standards based on the actual emissions of ``the best controlled
similar unit'' or ``best-performing 12 percent of units in the
category'' for each covered pollutant. Even if we were to conclude that
the commenters' interpretation is equally reasonable under the statute,
which we do not, the commenters' interpretation is certainly not
compelled by the statute. We maintain that our interpretation is
reasonable under the

statute and appropriate given the problems associated with implementing
the commenters' approach.
    Commenters' interpretation also ignores the rest of the CAA section
129. That provision requires EPA to ``establish performance standards
and other requirements pursuant to section [111] of this title and this
section [129] for each category of solid waste incineration units.''
Pursuant to CAA section 129(a)(2), those standards ``shall reflect the
maximum degree of reduction in emissions of air pollutants listed under
section (a)(4) that the Administrator, taking into consideration the
cost of achieving such emission reduction, and any nonair quality
health and environmental impacts and energy requirements, determines is
achievable for new or existing units in each category'' (emphasis
added). Subsection (a)(4) then states: ``The performance standards
promulgated under section [111] of this title and this section [129]
and applicable to solid waste incineration units shall specify
numerical emissions limitations for the following substances or
mixtures: particulate matter (total and fine), opacity (as
appropriate), sulfur dioxide, hydrogen chloride, oxides of nitrogen,
carbon monoxide, lead, cadmium, mercury, and dioxins and furans.''
Thus, the statute requires EPA to set individual numeric (a)
Performance standards; (b) based on the maximum degree of reduction in
emissions actually achieved; (c) for each of nine listed pollutants.
Based on this, EPA believes--and has long believed--the statute
supports, if not requires, that MACT floors be derived for each
pollutant based on the emissions levels achieved for each pollutant.
    Looking at the statute as a whole, EPA declared in 1997 rulemaking
for medical waste incinerators: ``The EPA does not agree that the MACT
floors are to be based upon one overall unit'' (62 FR 48364). Pointing
for instance to CAA section 129(a)(4), EPA explained:

    This provision certainly appears to direct maximum reduction of
each specified pollutant. Moreover, although the provisions do not
state whether there is to be a separate floor for each pollutant,
the fact that Congress singled out these pollutants suggests that
the floor level of control need not be limited by the performance of
devices that only control some of these pollutants well.

Id.

    Since 1997, the courts have consistently acknowledged that EPA set
emission standards based on the best-performing source for each
pollutant. See, e.g., Cement Kiln, 255 F.3d 855, 858 (DC Cir.) (``[T]he
Agency first sets emission floors for each pollutant and source
category * * *''). Accordingly, EPA's pollutant-by-pollutant approach
has, as outlined above, been in place since 1997 for medical waste
incinerators, and even earlier for other types of incinerators
regulated under section 129. See, e.g., 59 FR 48198 (Sept. 20, 1994)
(MWC). Commenters fail to cite to a single case even questioning EPA's
pollutant-by-pollutant approach. In addition, such an approach has been
upheld in other contexts. See, e.g., Chemical Manufacturers Association
v. EPA, 870 F.2d 177, 239 (5th Cir. 1989) (concluding that basing CWA
BAT standards on a pollutant-by-pollutant basis was a rational
interpretation of EPA's obligations under that similar statute).
Commenters maintain that the CWA BAT analogy is not apt due to
differences in the statute. We disagree and note that the CAA MACT
provisions were fashioned on that CWA program. S. Rep. No. 228, 101st
Cong. 2d sess. 133-34.
    Further, utilizing the single-unit theory proffered by commenters
would likely result in EPA setting the standards at levels that could,
for some pollutants, actually be based on emissions limitations
achieved by the worst-performing unit, rather than the best-performing
unit, as required by the statute (61 FR 173687, April 19, 1996; 62 FR
48363-64, September 15, 1997). For example, if the best-performing 12
percent of facilities for metals did not control PCDD/PCDF as well as a
different 12 percent of facilities, the floor for PCDD/PCDF and metals
would end up not reflecting best performance. Moreover, a single-unit
approach would require EPA to make value judgments as to which
pollutant reductions are most critical in working to identify the
single unit that reduces emissions of the nine pollutants on an overall
best-performing basis. Such value judgments are antithetical to the
command of the statute at the MACT floor stage. It would essentially
require EPA to prioritize the nine pollutants based on the relative
risk to human health of each pollutant, a criterion that has no place
in the establishment of MACT floors. The idea is to set limits that, as
an initial matter, require all sources in a category to at least clean
up their emissions to the level that their best performing peers have
shown can be achieved. Sierra Club v. EPA (Copper Smelters), 353 F.3d
976, 979-80 (DC Cir. 2004).
    Commenters' argument that Congress could have mandated a pollutant-
by-pollutant result by using the phrase ``for each pollutant'' at
appropriate points in CAA section 129(a)(2) misses the point. While
doing so would have removed ambiguity from CAA section 129(a)(2), the
fact that the statute does not contain the phrase does not compel any
inference that Congress was sub silentio mandating a different result
when it left the provision ambiguous on this issue. The argument that
MACT floors set pollutant-by-pollutant are based on the performance of
a hypothetical facility, so that the limitations are not based on those
achieved in practice, just re-begs the question of whether CAA section
129(a)(2) refers to whole facilities or individual pollutants. All of
the limitations in the floors in this rule of course reflect sources'
actual performance and were achieved in practice.
    An interpretation that the floor level of control must be limited
by the performance of devices that only control some of these
pollutants effectively ``guts the standards'' by including worse
performers in the averaging process, whereas EPA's interpretation
promotes the evident Congressional objective of having the floor
reflect the average performance of best-performing sources. Since
Congress has not spoken to the precise question at issue, and EPA's
interpretation effectuates statutory goals and policies in a reasonable
manner, its interpretation must be upheld. See Chevron v. NRDC, 467
U.S. 837 (1984).
    The legislative history can sometimes be so clear as to give clear
meaning to what is otherwise ambiguous statutory text, but that is not
the case with the legislative history cited by the commenters: ``The
selection of emissions limitations which have been achieved in practice
(rather than those which are merely theoretical) by sources of a
similar type or character. An emissions limitation achieved in practice
is one based on control technology that works reasonably well (doesn't
require frequent and extensive modification or repair) under realistic
operating conditions.'' See S. Rep. No. 228, 101st Cong., 1st Sess. 169
(1989). In fact, that language quoted equally supports EPA's approach
of establishing the standards based on actual emission data from
existing sources, which we consider realistic operating conditions. We
further consider whether all the MACT standards can be achieved
simultaneously under realistic operating conditions by evaluating the
compatibility of different control technologies for the various 129
pollutants, as discussed below.
    Commenters also make much of the fact that no single facility is
presently achieving all of the nine pollutant limits proposed. But this
fact is irrelevant, and only shows that plants will need to reduce
their emissions of certain

pollutants to meet standards reflecting the average of best industry
performers for that pollutant. We recognize that the pollutant-by-
pollutant approach for determining the MACT floor can, as it does in
this case, increase the overall cost of the regulation compared to the
cost under a unit-based methodology. For example, the pollutant-by-
pollutant approach for the CISWI regulation results in a stringent MACT
floor for HCl based on control using a wet scrubber, and stringent MACT
floors for PM and metals based on control using a FF. We interpret CAA
section 129 to support determining the MACT floor in this manner, and
we believe that Congress did in fact, intend that sources subject to
regulations developed under CAA section 129 meet emissions limits that
are achieved by the best controlled unit for each pollutant, as long as
the control systems are compatible with each other. To our knowledge,
there is no technical reason why these air pollution control systems
cannot be combined. Regarding the inverse relationship between CO and
NOX with regard to combustion control, it is incumbent upon
the CISWI facility to determine whether combustion conditions can be
adjusted to meet both standards and, if not, install add-on
NOX controls as necessary, e.g., SNCR systems.
    All available data for cement kilns indicate that there is no