[Federal Register Volume 76, Number 54 (Monday, March 21, 2011)]
[Rules and Regulations]
[Pages 15372-15454]
[FR Doc No: 2011-4491]

Vol. 76

Monday,

No. 54

March 21, 2011

Part II

Environmental Protection Agency

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40 CFR Part 60

Standards of Performance for New Stationary Sources and Emission
Guidelines for Existing Sources: Sewage Sludge 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-2009-0559; FRL-9272-9]
RIN 2060-AP90

Standards of Performance for New Stationary Sources and Emission
Guidelines for Existing Sources: Sewage Sludge Incineration Units

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: This action promulgates EPA's new source performance standards
and emission guidelines for sewage sludge incineration units located at
wastewater treatment facilities designed to treat domestic sewage
sludge. This final rule sets limits for nine pollutants under section
129 of the Clean Air Act: Cadmium, carbon monoxide, hydrogen chloride,
lead, mercury, nitrogen oxides, particulate matter, polychlorinated
dibenzo-p-dioxins and polychlorinated dibenzofurans, and sulfur
dioxide.

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

ADDRESSES: EPA established a single docket under Docket ID No. EPA-HQ-
OAR-2009-0559 for this action. This docket includes previous actions
including the standards proposed on October 14, 2010 (75 FR 63260) and
a supplemental notice issued on November 5, 2010 (75 FR 68296). 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 (202)
566-1744, and the telephone number for the EPA Docket Center is (202)
566-1742.

FOR FURTHER INFORMATION CONTACT: Ms. Amy Hambrick, Natural Resource and
Commerce Group, Sector Policies and Programs Division (E143-03),
Environmental Protection Agency, Research Triangle Park, North Carolina
27711; telephone number:<PHONE_NUMBER>; fax 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-Polycyclic Aromatic Hydrocarbons
ANSI American National Standards Institute
As Arsenic
ASME American Society of Mechanical Engineers
ASTM American Society of Testing and Materials
CAA Clean Air Act
CASS Continuous Automated Sampling System
CBI Confidential Business Information
Cd Cadmium
CDX Central Data Exchange
CEMS Continuous Emissions Monitoring Systems
COMS Continuous Opacity Monitoring System
The Court U.S. Court of Appeals for the District of Columbia Circuit
CPMS Continuous Parametric Monitoring System
CFR Code of Federal Regulations
CISWI Commercial and Industrial Solid Waste Incineration
CO Carbon Monoxide
Cr Chromium
CWA Clean Water Act
EG Emission Guidelines
EJ Environmental Justice
ERT Electronic Reporting Tool
ESP Electrostatic Precipitators
FF Fabric Filter
FB Fluidized Bed
FGR Flue Gas Recirculation
HAP Hazardous Air Pollutants
HCl Hydrogen Chloride
Hg Mercury
HMIWI Hospital, Medical and Infectious Waste Incineration
ICR Information Collection Request
ISTDMS Integrated Sorbent Trap Dioxin Monitoring System
ISTMMS Integrated Sorbent Trap Mercury Monitoring System
LML Lowest Measured Level
MACT Maximum Achievable Control Technology
Mg/dscm Milligrams per Dry Standard Cubic Meter
MH Multiple Hearth
Mn Manganese
MWC Municipal Waste Combustion
NAAQS National Ambient Air Quality Standards
NAICS North American Industrial Classification System
Ng/dscm Nanograms per Dry Standard Cubic Meter
Ni Nickel
NOX Nitrogen Oxides
NPRM Notice of Proposed Rulemaking
NSPS New Source Performance Standards
NTAA National Tribal Air Association
NTTAA National Technology Transfer and Advancement Act of 1995
OAQPS Office of Air Quality Planning and Standards
O&M Operation and Maintenance
OMB Office of Management and Budget
OP Office of Policy
OSWI Other Solid Waste Incineration
OTM Other Test Method
OW Office of Water
Pb Lead
PCB Polychlorinated Biphenyls
PCDD/PCDF Polychlorinated Dibenzo-P-Dioxins and Polychlorinated
Dibenzofurans
PM Particulate Matter
POM Polycyclic Organic Matter
POTW Publicly Owned Treatment Works
PPM Parts per Million
PPMV Parts per Million by Volume
PPMVD Parts per Million of Dry Volume
PRA Paperwork Reduction Act
PS Performance Specifications
RCRA Resource Conservation and Recovery Act
RFA Regulatory Flexibility Act
RIA Regulatory Impact Analysis
RTO Regenerative Thermal Oxidizer
SBA Small Business Administration
SCR Selective Catalytic Reduction
SNCR Selective Non-Catalytic Reduction
SO2 Sulfur Dioxide
SSI Sewage Sludge Incineration
SSM Startup, Shutdown, and Malfunction
TEF Toxic Equivalency Factor
TEQ Toxic Equivalency
THC Total Hydrocarbons
TMB Total Mass Basis
TPD Tons per Day
TPY Tons per Year
TTN Technology Transfer Network
UL Upper Limit
UMRA Unfunded Mandates Reform Act of 1995
UPL Upper Prediction Limit
VCS Voluntary Consensus Standards
WWW Worldwide Web

    Organization of This Document. The following outline is provided to
aid in locating information in this preamble.

I. General Information
    A. Does the action apply to me?
    B. Where can I get a copy of this document?
    C. Judicial Review
II. Background
    A. What is the statutory background for this final rule?
    B. What are the primary sources of emissions and what are the
emissions?
    C. What is the relationship of the final standards to other
standards for the use or disposal of sewage sludge and associated
air emissions?
III. Summary of the Final Standards
    A. What units are affected by the final standards?
    B. What are the emission limits in the emission guidelines for
existing sources?
    C. What are the emission limits in the new source performance
standards for new sources?

    D. What are the testing and monitoring requirements?
    E. What are the other requirements for new and existing SSI
units?
    F. What are the recordkeeping and reporting requirements?
    G. What are the SSM provisions?
    H. What are the Title V permit requirements?
    I. What are the applicability dates of the standards?
    J. What are the requirements for submission of emissions test
results to EPA?
IV. Summary of Significant Changes Following Proposal
    A. Applicability
    B. Subcategories
    C. MACT Floor UPL Calculation and EG and NSPS Emission Limits
    D. Baseline Emissions, Costs, and Impacts Estimation
    E. Compliance Requirements
    F. Definitions
V. Significant Public Comments and Rationale for Changes to the
Proposed Rule
    A. Legal and Applicability Issues Regulating SSI Under Section
112 vs. Section 129
    B. Subcategories
    C. MACT Floor Analysis
    D. Baseline Emissions
    E. Beyond-the-Floor Analysis
    F. Cost and Economic Impacts
    G. Startup, Shutdown, and Malfunction
    H. Compliance Requirements
VI. Impacts of the Final Action
    A. Impacts of the Final Action for Existing Units
    B. Impacts of the Final Action for New Units
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

I. General Information

A. Does this action apply to me?

    Categories and entities potentially affected by the final action
are those that operate sewage sludge incinerators (SSI). Although there
is no specific NAICS code for SSI, these units may be operated by
wastewater treatment facilities designed to treat domestic sewage
sludge. The following NAICS codes could apply:

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                                                         Examples of
             Category                 NAICS code         potentially
                                                     regulated entities
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Solid waste combustors and                  562213  Municipalities with
 incinerators.                                       SSI units.
Sewage treatment facilities.......          221320  ....................
------------------------------------------------------------------------

    This table is not intended to be exhaustive, but rather provides a
general guide for identifying entities likely to be affected by the
final action. To determine whether your facility would be affected by
the final action, you should examine the applicability criteria in 40
CFR 60.4770 of subpart LLLL and proposed 40 CFR 60.5005 of subpart
MMMM. 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 this final rule that was raised with reasonable
specificity during the period for public comment can be raised during
judicial review.'' This section also provides a mechanism for EPA 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 this rule.'' Any person seeking
to make such a demonstration to EPA 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

A. What is the statutory background 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.'' 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)). Sections 111(b) and 129(a) of the CAA address emissions
from new units (i.e., NSPS), and CAA sections 111(d) and 129(b) address
emissions from existing units (i.e., EG). The NSPS are directly
enforceable Federal regulations, and under CAA section 129(f)(1),
become effective 6 months after promulgation. Unlike the NSPS, the EG
are not themselves directly enforceable. Rather, the EG are implemented
and enforced through either an EPA-approved state plan or a promulgated
Federal plan.

States are required to submit a plan to implement and enforce the EG to
EPA for approval not later than 1 year after EPA promulgates the EG
(CAA section 129(b)(2)). The state plan must be ``at least as
protective as'' the EG and must ensure compliance with all applicable
requirements not later than 3 years after the state plan is approved by
EPA, or 5 years after promulgation of the relevant EG, whichever is
sooner. EPA's procedures for submitting and approving state plans are
set forth in 40 CFR part 60, subpart B. When a state plan is approved
by EPA, the plan requirements become federally enforceable, but the
state has primary responsibility for implementing and enforcing the
plan. However, EPA is required to develop, implement, and enforce a
Federal plan for solid waste incineration units located in any state
which has not submitted an approvable state plan within 2o years after
the date of promulgation of the relevant EG (CAA section 129(b)(3)).
The Federal plan must assure that each solid waste incineration unit
subject to the Federal plan is in compliance with all provisions of the
EG not later than 5 years after the date the relevant guidelines are
promulgated. EPA views the Federal plan as a ``place-holder'' that
remains in effect only until such time as a state without an approved
plan submits and receives EPA approval of its state plan. Once an
applicable state plan has been approved, the requirements of the
Federal plan no longer apply to solid waste incineration units covered
by that state plan.
    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.
    In setting forth the methodology EPA must use to establish the
first-stage technology-based standards for the standards, 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, state regulatory requirements that may enable
EPA to estimate the actual performance of the regulated units, or other
emissions information. 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 also be used, if the methods can be shown to provide
reasonable estimates of the actual emissions performance of a source or
sources. In addition to the MACT floor limit, EPA must examine whether
more stringent ``beyond-the-floor'' standards should be adopted. In
considering whether such standards are appropriate, EPA must consider
the cost of achieving such emission reduction, and any non-air quality
health and environmental impacts and energy requirements. The CAA
requires that the MACT floor for new sources be no less stringent than
the emissions control achieved in practice by the best-controlled
similar unit. EPA is also required to consider beyond-the-floor
standards for new sources, consistent with the factors described above.
Clean Air Act section 129(a)(1) identifies five categories of solid
waste incineration units:
     Units that combust municipal waste at a capacity greater
than 250 tpd.
     Units that combust municipal waste at a capacity equal to
or less than 250 tpd.
     Units that combust hospital, medical, and infectious
waste.
     Units that combust commercial or industrial waste.
     Units that combust waste and which are not specifically
identified in section 129(a)(1)(A) through (D) are referred to in
section 129(a)(1)(E) as ``other categories'' of solid waste
incineration units.
    A SSI unit is an incinerator located at a wastewater treatment
facility designed to treat domestic sewage sludge that combusts sewage
sludge for the purpose of reducing the volume of the sewage sludge by
removing combustible matter. Sewage sludge incinerators, by virtue of
having not been specifically identified in section 129(a)(1)(A) through
(D), have been interpreted to be part of the broader category of
``other categories'' of solid waste. EPA has issued emission standards
for large and small MWC, HMIWI, CISWI, and OSWI units; however, as
explained further below, none of those emission standards apply to SSI
units.
    EPA issued emission standards for OSWI units on December 16, 2005
(70 FR 74870). Based on EPA's interpretation of the CAA at that time,
the OSWI standards did not include emission standards for SSI units.
EPA received a petition for reconsideration of the OSWI standards on
February 14, 2006, regarding the exclusion of certain categories,
including SSI.\1\ While EPA granted the petition for reconsideration on
June 28, 2006, EPA's final review, which became effective January 22,
2007, concluded that no additional changes were necessary to the 2005
OSWI rule (71 FR 36726). That litigation is currently being held in
abeyance. EPA currently intends to revise the emission standards for
OSWI units in the future,

and that rulemaking will address all OSWI units except SSI units.
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    \1\ Sierra Club v. EPA; DC Cir. Nos. 06-1066, 07-1063.
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    In the OSWI rule issued on December 16, 2005, EPA stated that it
had decided not to regulate SSI units under CAA section 129 (70 FR
74870), but rather to regulate SSI units under CAA section 112,
pointing to a statement in EPA's 2000 Unified Regulatory Agenda stating
that sewage sludge incinerators do not combust waste from a commercial
or industrial establishment or the general public. We declined to
revise that decision to regulate SSI units under 112 in the response to
the petition for reconsideration on this issue for five reasons,
including our position that section 129(a)(1)(E) did not require
regulation of all ``other'' solid waste incineration units and that
section 129(g)(1)'s enumerated exemptions to the definition of ``solid
waste incineration unit'' were not exclusive, and that section
129(h)(2) gave EPA the discretion to choose whether to regulate
incinerators under section 112 or section 129 of the Act. (72 FR 2620).
In June 2007, in a separate decision related to EPA's December 1, 2000,
emission standards for CISWI units, the Court held that any unit
combusting any solid waste must be regulated under section 129 of the
CAA. The impact of this decision on EPA's regulation of SSI is
explained in detail in the NPRM.\2\
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    \2\ NRDC v. EPA; 489 F. 3d. at 1257-8.
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    EPA considers SSI units to be ``other solid waste incineration
units,'' since that category is intended to encompass all solid waste
incineration units that are not included in the first four categories
identified in CAA section 129(a) through (d). EPA plans to re-issue
emission standards for the remaining OSWI units at a later time. EPA is
taking final action on emission standards for SSI units at this time
because these emission standards are needed as part of EPA's
fulfillment of its obligations under CAA sections 112(c)(3) and
(k)(3)(B)(ii) and section 112(c)(6). Clean Air Act section
112(k)(3)(B)(ii) calls for EPA to identify at least 30 HAP which, as
the result of emissions from area sources, pose the greatest threat to
public health in the largest number of urban areas. EPA must then
ensure that sources representing 90 percent of the aggregate area
source emissions of each of the 30 identified HAP are subject to
standards pursuant to section 112(d).\3\ Sewage sludge incineration
units are one of the source categories identified for regulation to
meet the 90 percent requirement for Cd, Cr, Pb, Mn, Hg, Ni and PCB. EPA
is ordered by the Court to satisfy its obligation under CAA section
112(c)(3) and (k)(3)(B)(ii) by January 16, 2011.\4\
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    \3\ CAA section 112(c)(3) and section 112(k)(3)(B)(ii).
    \4\ Sierra Club v. Jackson; D.DC No. 1:01CV01537.
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    In a notice on April 10, 1998, EPA provided a list of source
categories for regulation under CAA section 112(d)(2) or 112(d)(4).
Section 112(c)(6) of the CAA requires EPA to identify categories of
sources of seven specified pollutants to assure that sources counting
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) (63 FR 17838). Sewage sludge incineration units are one of
the identified source categories for regulation to meet the 90 percent
requirement for Hg. Further information can be found in the Memorandum
titled, ``Emission Standards for Meeting the Ninety Percent Requirement
under Section 112(c)(6) of the Clean Air Act'' in the SSI docket (EPA-
HQ-OAR-2009-0559).Therefore, EPA is finalizing the SSI standards prior
to taking action on the remaining source categories that will be
regulated under CAA section 129(a)(1)(E) as OSWI units.

B. What are the primary sources of emissions and what are the
emissions?

    Sewage sludge incineration units may be operated by municipalities
or other entities. Incineration continues to be used to dispose of
sewage sludge. Combustion of solid waste, and specifically sewage
sludge, causes the release of a wide array of air pollutants, some of
which exist in the waste feed material and are released unchanged
during combustion, and some of which are generated as a result of the
combustion process itself. The pollutants for which numerical limits
must be established, as specified in section 129 of the CAA, include
Cd, CO, HCl, Hg, NOX, PCDD/PCDF, PM, Pb, and SO2;
and, where appropriate, numerical limits for opacity must also be
established. These emissions come from the SSI unit's stack and
fugitive PM emissions, as indicated by the associated visible
emissions, also occur from ash handling.

C. What is the relationship of the final standards to other standards
for the use or disposal of sewage sludge and associated air emissions?

    Under authority of section 405(d) and (e) of the CWA, as amended 33
U.S.C.A. 1251, (et seq.), EPA promulgated regulations on February 19,
1993, at 40 CFR part 503 designed to protect public health and the
environment from any reasonably anticipated adverse effects of certain
pollutants that may be present in sewage sludge. The part 503
regulations establish requirements for the final use and disposal of
sewage sludge when: (1) The sludge is applied to the land for a
beneficial use (e.g., for use in home gardens); (2) the sludge is
disposed on land by placing it on surface disposal sites; and (3) the
sewage sludge is incinerated. The standards apply to POTW that generate
or treat domestic sewage sludge, as well as to any person who uses or
disposes of sewage sludge from such treatment works.
    The part 503 requirements for firing sewage sludge in a SSI are in
subpart E of the regulations. Subpart E includes general requirements;
pollutant limits; operational standards; management practices; and
monitoring, recordkeeping, and reporting requirements.
    These part 503 regulations require that SSI meet the National
Emission Standards for Beryllium and Hg in subparts C and E,
respectively, of 40 CFR part 61. The regulations also require that the
allowable concentration of five other inorganic pollutants be
calculated using equations in the regulation. The inorganic pollutants
included are Pb, As, Cd, Cr, and Ni. The terms in the equations must be
determined on a case-by-case basis, except for the risk-specific
concentration for the inhalation exposure pathway to protect
individuals when these pollutants are inhaled. The site-specific
variables for the equations (incinerator type, dispersion factor,
control efficiency, feed rate, and stack height) must be used to
calculate allowable daily concentrations of As, Cd, Cr, Pb and Ni in
the sewage sludge fed to the incinerator.
    Also included in subpart E of part 503 is an operational standard
for THC. The value for THC in the final part 503 regulation cannot be
exceeded in the exit gas from the SSI stack. Management practices and
frequency of monitoring, recordkeeping, and reporting requirements are
also included in this subpart.
    Under today's final standards, EPA is establishing limits for three
of the inorganic pollutants covered by the current part 503 regulations
(Cd, Pb and Hg) and the following six additional pollutants: HCl, CO,
NOX, SO2, PM, and total PCDD/PCDF. Besides the
pollutants covered here, there are other differences between the part
503 regulations and these final standards. The emission limits for
inorganic pollutants under part 503 are risk-based numbers rather than
technology-based. Also, part 503 does not distinguish between new and
existing units or between incinerator types (i.e., MH or

FB incinerator) for setting emission limits since emission limits are
based on risks to a highly exposed individual.
    Because both part 503 and these final standards cover the same
universe of facilities, there are certain issues that arise in terms of
potential impacts to current SSI facilities. First, the regulation of
sewage sludge under CAA section 129 will result in stricter emission
standards than under the current CWA rule. Additional pollution
controls will increase costs for facilities that continue to use the
incineration disposal method. If the additional costs are high enough,
many entities may choose to adopt alternative disposal methods (e.g.,
surface disposal in landfills or other beneficial land applications).
Consequently, a potential impact of this rule is that some of the
estimated 110 facilities that operate SSI as the primary means of
disposal could discontinue this practice and would instead landfill or
land apply their sewage sludge. Second, one must consider the available
capacity of surface disposal sites to receive additional sewage sludge
and the potential for added costs if the use of SSI is discontinued.
Third, SSI will be subject to two different sets of requirements
(numeric standards, operational standards, monitoring, recordkeeping,
and reporting) under the two different statutes, creating an additional
burden to these facilities unless alternative regulatory approaches are
implemented. EPA plans to evaluate the requirements under both statutes
to determine what changes, if any, should be made to the part 503
regulations.

III. Summary of the Final Standards

    This preamble discusses the final standards as they apply to the
owner or operator of a new or existing SSI unit. This preamble also
describes the major requirements of the SSI regulations. For a full
description of the final requirements and compliance times, see the SSI
standards in subparts LLLL and MMMM.

A. What units are affected by the final standards?

    The final standards and guidelines apply to owners or operators of
SSI units (as defined in 40 CFR 60.4780 and 40 CFR 60.5065) located at
wastewater treatment facilities designed to treat domestic sewage
sludge. A SSI unit is an enclosed device or devices using controlled
flame combustion that burns sewage sludge for the purpose of reducing
the volume of the sewage sludge by removing combustible matter. A SSI
unit also includes, but is not limited to, the sewage sludge feed
system, auxiliary fuel feed system, grate system, flue gas system,
waste heat recovery equipment, if any, and bottom ash system. The SSI
unit includes all ash handling systems connected to the bottom ash
handling system. The combustion unit bottom ash system ends at the
truck loading station or similar equipment that transfers the ash to
final disposal. The SSI unit does not include air pollution control
equipment or the stack. The affected facility is each individual SSI
unit. The SSI standards in subparts LLLL and MMMM apply to new and
existing SSI units that burn sewage sludge as defined in the subparts.
The final standards define two subcategories for new and existing SSI
units: MH incinerators and FB incinerators.
    The combustion of sewage sludge that is not burned in a SSI unit
located at a wastewater treatment facility designed to treat domestic
sewage sludge is subject to other section 129 standards, such as the
CISWI standards (40 CFR part 60, subparts CCCC and DDDD of this part),
the OSWI standards (40 CFR part 60, subparts EEEE and FFFF), the MWC
standards (40 CFR part 60, subparts Ea, Eb, Cb, AAAA, and BBBB of this
part) or the Hazardous Waste Combustor rule (40 CFR part 63 subpart
EEE).

B. What are the emission limits in the emission guidelines for existing
sources?

    The final emission limits for existing sources in the MH
incinerator subcategory and FB incinerator subcategory are presented in
Table 1 of this preamble. Existing sources may comply with either the
PCDD/PCDF TEQ or TMB emission limits.
    These standards apply at all times.

                                 Table 1--Emission Limits for Existing SSI Units
----------------------------------------------------------------------------------------------------------------
                                                                               Emission limit    Emission limit
                  Pollutant                                Units                   for MH            for FB
                                                                                incinerators      incinerators
----------------------------------------------------------------------------------------------------------------
Cd..........................................  mg/dscm @ 7% O2...............             0.095            0.0016
CO..........................................  ppmvd @ 7% O2.................             3,800                64
HCl.........................................  ppmvd @ 7% O2.................               1.2              0.51
Hg..........................................  mg/dscm @ 7% O2...............              0.28             0.037
NOX.........................................  ppmvd @ 7% O2.................               220               150
Pb..........................................  mg/dscm @ 7% O2...............              0.30            0.0074
PCDD/PCDF, TEQ..............................  ng/dscm @ 7% O2...............              0.32              0.10
PCDD/PCDF, TMB..............................  ng/dscm @ 7% O2...............               5.0               1.2
PM..........................................  mg/dscm @ 7% O2...............                80                18
SO2.........................................  ppmvd @ 7% O2.................                26                15
----------------------------------------------------------------------------------------------------------------

C. What are the emission limits in the new source performance standards
for new sources?

    The final emission limits for new sources in the MH incinerator
subcategory and FB incinerator subcategory are presented in Table 2 of
this preamble. Existing sources may comply with either the PCDD/PCDF
TEQ or TMB emission limits.
    These standards apply at all times.

                                   Table 2--Emission Limits for New SSI Units
----------------------------------------------------------------------------------------------------------------
                                                                               Emission limit    Emission limit
                  Pollutant                                Units                   for MH            for FB
                                                                                incinerators      incinerators
----------------------------------------------------------------------------------------------------------------
Cd..........................................  mg/dscm @ 7% O2...............            0.0024            0.0011
CO..........................................  ppmvd @ 7% O2.................                52                27
HCl.........................................  ppmvd @ 7% O2.................               1.2              0.24

Hg..........................................  mg/dscm @ 7% O2...............              0.15            0.0010
NOX.........................................  ppmvd @ 7% O2.................               210                30
Pb..........................................  mg/dscm @ 7% O2...............            0.0035           0.00062
PCDD/PCDF, TMB..............................  ng/dscm @ 7% O2...............             0.045             0.013
PCDD/PCDF, TEQ..............................  ng/dscm @ 7% O2...............            0.0022            0.0044
PM..........................................  mg/dscm @ 7% O2...............                60               9.6
SO2.........................................  ppmvd @ 7% O2.................                26               5.3
----------------------------------------------------------------------------------------------------------------

D. What are the testing and monitoring requirements?

    These final standards require all new and existing SSI units to
demonstrate initial and annual compliance with the emission limits
using EPA-approved emission test methods. The final standards also
provide an option for less frequent testing if sources demonstrate that
their emissions of regulated pollutants are below thresholds of the
emission limits.
    For existing SSI units, the EG requires initial and annual
emissions performance tests (or continuous emissions monitoring or
continuous sampling as an alternative), bag leak detection systems for
FF controlled units, continuous parameter monitoring, and annual
inspections of air pollution control devices, if they are used to meet
the emission limits. Additionally, existing units are required to
conduct Method 22 (see 40 CFR part 60, appendix A-7) visible emissions
test of the ash handling operations during each compliance test.
    For new SSI units, the NSPS requires initial and annual emissions
performance tests (or continuous emissions monitoring or continuous
sampling as an alternative), bag leak detection systems for FF
controlled units, as well as continuous parameter monitoring and annual
inspections of air pollution control devices that may be used to meet
the emission limits. The final rule requires all new SSI units to
install a CO CEMS. Operators of new units are also required to conduct
Method 22 visible emissions testing of the ash handling operations
during each compliance test.
    For existing SSI units, use of Cd, CO, HCl, NOX, PM, Pb
or SO2 CEMS; ISTMMS; and ISTDMS (continuous sampling with
periodic sample analysis) are approved alternatives to parametric
monitoring and annual compliance testing. For new SSI units, CO CEMS
are required, and use of Cd, HCl, NOX, PM, Pb or
SO2 CEMS; ISTMMS; and ISTDMS (continuous sampling, with
periodic sample analysis) are approved alternatives to parametric
monitoring and annual compliance testing.

E. What are the other requirements for new and existing SSI units?

    Owners or operators of new or existing SSI units are required to
meet operator training and qualification requirements, which include:
Ensuring that at least one operator or supervisor per facility complete
the operator training course, that qualified operator(s) or
supervisor(s) complete an annual review or refresher course specified
in the regulation, and that they maintain plant-specific information,
updated annually, regarding training.
    Owners or operators of new SSI units are required to conduct a
siting analysis, which includes submitting a report that evaluates
site-specific air pollution control alternatives that minimize
potential risks to public health or the environment, considering costs,
energy impacts, non-air environmental impacts and any other factors
related to the practicability of the alternatives.
    Owners or operators of new or existing SSI units are required to
submit a monitoring plan for any continuous monitoring system or bag
leak detection system used to comply with the rule. They must also
submit a monitoring plan for their ash handling system that specifies
the operating procedures they will follow to ensure that they meet the
fugitive emission limit.

F. What are the recordkeeping and reporting requirements?

    Records of the initial and all subsequent stack or PS tests,
deviation reports, operating parameter data, continuous monitoring
data, maintenance and inspections of the air pollution control devices,
the siting analysis (for new units only), monitoring plan and operator
training and qualification must be maintained for 5 years. The results
of the stack tests and PS tests and values for operating parameters are
required to be included in initial and subsequent compliance reports.

G. What are the SSM provisions?

    The Court vacated portions of two provisions in EPA's CAA section
112 regulations governing the emissions of HAP during periods of SSM.
Sierra Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008), cert. denied, 130
S. Ct. 1735 (U.S. 2010). Specifically, the Court vacated the SSM
exemption contained in 40 CFR 63.6(f)(1) and 40 CFR 63.6(h)(1), (the
``General Provisions Rule,'') that EPA promulgated under section 112 of
the CAA. When incorporated into CAA section 112(d) regulations for
specific source categories, these two provisions exempt sources from
the requirement to comply with the otherwise applicable CAA section
112(d) emission standard during periods of SSM.
    While the Court's ruling in Sierra Club v. EPA directly affects
only the subset of CAA section 112(d) rules that incorporate 40 CFR
63.6(f)(1) and (h)(1) by reference and that contain no other regulatory
text exempting or excusing compliance during SSM events, the legality
of source category-specific SSM provisions is questionable.
    Consistent with Sierra Club v. EPA, EPA is requiring that emission
limitations in these final standards apply at all times the unit is
operating. In establishing these standards, EPA has taken into account
startup and shutdown periods and, for the reasons explained below, has
not established different standards for those periods.
    We are not promulgating a separate emission standard for the source
category that applies during periods of startup and shutdown. Based on
the information available at this time, we believe that SSI units will
be able to meet the emission limits during periods of startup. Units we
have information on use natural gas, landfill gas, or distillate oil to
start the unit and add waste once the unit has reached combustion
temperatures. Emissions from burning natural gas, landfill gas or
distillate fuel oil are expected to generally be lower than from
burning solid wastes. Emissions during periods of shutdown are also
generally lower than emissions during normal operations because the

materials in the incinerator would be almost fully combusted before
shutdown occurs. Furthermore, the approach for establishing MACT floors
for SSI units ranked individual SSI units based on actual performance
for each pollutant and subcategory, with an appropriate accounting of
emissions variability. Because we accounted for emissions variability,
we believe we have adequately addressed any minor variability that may
potentially occur during startup or shutdown.
    Periods of startup, normal operations, and shutdown are predictable
and routine aspects of a source's operations. However, by contrast,
malfunction is defined as a ``sudden, infrequent, and not reasonably
preventable failure of air pollution control and monitoring equipment,
process equipment or a process to operate in a normal or usual manner *
* * '' (40 CFR 60.2). EPA has determined that malfunctions should not
be viewed as a distinct operating mode and, therefore, any emissions
that occur at such times do not need to be factored into development of
CAA section 129 standards, which, once promulgated, apply at all times.
Nothing in CAA section 129 or in case law requires that EPA anticipate
and account for the innumerable types of potential malfunction events
in setting emission standards.\5\
---------------------------------------------------------------------------

    \5\ See, Weyerhaeuser v. Costle, 590 F.2d 1011, 1058 (DC Cir.
1978) (``In the nature of things, no general limit, individual
permit, or even any upset provision can anticipate all upset
situations. After a certain point, the transgression of regulatory
limits caused by `uncontrollable acts of third parties,' such as
strikes, sabotage, operator intoxication or insanity, and a variety
of other eventualities, must be a matter for the administrative
exercise of case-by-case enforcement discretion, not for
specification in advance by regulation.'').
---------------------------------------------------------------------------

    Further, it is reasonable to interpret CAA section 129 as not
requiring EPA to account for malfunctions in setting emissions
standards. For example, we note that CAA section 129 uses the concept
of ``best controlled'' or ``best performing'' sources in defining MACT,
the level of stringency that major source standards must meet. Applying
the concept of ``best controlled'' or ``best performing'' to a source
that is malfunctioning presents significant difficulties. The goal of
best controlled or best performing sources is to operate in such a way
as to avoid malfunctions of their units.
    Moreover, even if malfunctions were considered a distinct operating
mode, we believe it would be impracticable to take malfunctions into
account in setting CAA section 129 standards for SSI. As noted above,
by definition, malfunctions are sudden and unexpected events, and it
would be difficult to set a standard that takes into account the myriad
different types of malfunctions that can occur across all sources in
the category. Moreover, malfunctions can vary in frequency, degree, and
duration, further complicating standard setting.
    For the SSI standards, malfunctions are required to be reported in
deviation reports. We will then review the deviation reports to
determine if the deviation is a violation of the standards.
    In the event that a source fails to comply with the applicable CAA
section 129 standards as a result of a malfunction event, EPA would
determine an appropriate response based on, among other things, the
good faith efforts of the source to minimize emissions during
malfunction periods, including preventative and corrective actions, as
well as root cause analyses to ascertain and rectify excess emissions.
EPA would also consider whether the source's failure to comply with the
CAA section 129 standard was, in fact, ``sudden, infrequent, not
reasonably preventable'' and was not instead ``caused in part by poor
maintenance or careless operation.'' \6\
---------------------------------------------------------------------------

    \6\ 40 CFR 60.2 (definition of malfunction).
---------------------------------------------------------------------------

    Finally, EPA recognizes that even equipment that is properly
designed and maintained can fail and that such failure can sometimes
cause an exceedance of the relevant emission standard.\7\ EPA is
therefore finalizing the proposed affirmative defense to civil
penalties for exceedances of emissions limits that are caused by
malfunctions, with some revisions to the proposed regulatory
provision.\8\ Under this provision, the source must prove by a
preponderance of the evidence that it has met all of the elements set
forth in 40 CFR 60.4860 and in 40 CFR 60.5180. The criteria ensure that
the affirmative defense is available only where the event that causes
an exceedance of the emission limit meets the narrow definition of
malfunction in 40 CFR 60.2 (sudden, infrequent, not reasonable
preventable and not caused by poor maintenance and or careless
operation). For example, to successfully assert the affirmative
defense, the source must prove by a preponderance of the evidence that
excess emissions ``[w]ere caused by a sudden, infrequent, and
unavoidable failure of air pollution control and monitoring equipment,
process equipment, or a process to operate in a normal or usual manner
* * *.'' The criteria also are designed to ensure that steps are taken
to correct the malfunction, to minimize emissions in accordance with 40
CFR part 60, subpart LLLL and 40 CFR part 60, subpart MMMM and to
prevent future malfunctions. For example, the source must prove by a
preponderance of the evidence that ``[r]epairs were made as
expeditiously as possible when the applicable emission limitations were
being exceeded * * *'' and that ``[a]ll possible steps were taken to
minimize the impact of the excess emissions on ambient air quality, the
environment and human health * * *.'' In any judicial or administrative
proceeding, the Administrator may challenge the assertion of the
affirmative defense and, if the respondent has not met its burden of
proving all of the requirements in the affirmative defense, appropriate
penalties may be assessed in accordance with section 113 of the CAA
(see also 40 CFR 22.77).
---------------------------------------------------------------------------

    \7\ See, e.g., State Implementation Plans: Policy Regarding
Excessive Emissions During Malfunctions, Startup, and Shutdown
(Sept. 20, 1999); Policy on Excess Emissions During Startup,
Shutdown, Maintenance, and Malfunctions (Feb. 15, 1983).
    \8\ See proposed definition 40 CFR 60.4930 and 40 CFR 60.5250
(defining ``affirmative defense'' to mean, in the context of an
enforcement proceeding, a response or defense put forward by a
defendant, regarding which the defendant has the burden of proof,
and the merits of which are independently and objectively evaluated
in a judicial or administrative proceeding).
---------------------------------------------------------------------------

H. What are the Title V permit requirements?

    All new and existing SSI units regulated by the final SSI rule are
required to apply for and obtain a Title V permit. These Title V
operating permits assure compliance with all applicable requirements
for regulated SSI units, including all applicable CAA section 129
requirements.\9\
---------------------------------------------------------------------------

    \9\ 40 CFR 70.6(a)(1), 70.2, 71.6(a)(1) and 71.2.
---------------------------------------------------------------------------

    The permit application deadline for a CAA section 129 source
applying for a Title V operating permit depends on when the source
first becomes subject to the relevant Title V permits program. If a
regulated SSI unit is a new unit and is not subject to an earlier
permit application deadline, a complete Title V permit application must
be submitted on or before the relevant date below.
     For a SSI unit that commenced operation as a new source on
or before the promulgation date of 40 CFR part 60, subpart LLLL, the
source must submit a complete Title V permit application no later than
12 months after the promulgation date of 40 CFR part 60, subpart LLLL;
or
     For a SSI unit that commences operation as a new source
after the promulgation of 40 CFR part 60, subpart LLLL, the source must
submit a complete Title V permit application no

later than 12 months after the date the SSI unit commences operation as
a new source.\10\
---------------------------------------------------------------------------

    \10\ CAA section 503(c) and 40 CFR 70.5(a)(1)(i) and
71.5(a)(1)(i).
---------------------------------------------------------------------------

    If the SSI unit is an existing unit and is not subject to an
earlier permit application deadline, then the source must submit a
complete Title V permit application by the earlier of the following
dates:
     Twelve months after the effective date of any applicable
EPA-approved CAA section 111(d)/129 plan (i.e., an EPA approved state
or tribal plan that implements the SSI EG); or
     Twelve months after the effective date of any applicable
Federal plan; or
     Thirty-six months after promulgation of 40 CFR part 60,
subpart MMMM.
    For any existing SSI unit not subject to an earlier permit
application deadline, the application deadline of 36 months after the
promulgation of 40 CFR part 60, subpart MMMM, applies regardless of
whether or when any applicable Federal plan is effective, or whether or
when any applicable state or tribal CAA section 111(d)/129 plan is
approved by EPA and becomes effective. (See CAA sections 129(e),
503(c), 503(d), and 502(a) and 40 CFR 70.5(a)(1)(i) and 71.5(a)(1)(i).)
    If the SSI unit is subject to Title V as a result of some
triggering requirement(s) other than those mentioned above, for
example, a SSI unit may be a major source (or part of a major source),
then you may be required to apply for a Title V permit prior to the
deadlines specified above. If more than one requirement triggers a
source's obligation to apply for a Title V permit, the 12-month time
frame for filing a Title V permit application is triggered by the
requirement which first causes the source to be subject to Title V.\11\
---------------------------------------------------------------------------

    \11\ CAA section 503(c) and 40 CFR 70.3(a) and (b),
70.5(a)(1)(i), 71.3(a) and (b) and 71.5(a)(1)(i).
---------------------------------------------------------------------------

    For additional background information on the interface between CAA
section 129 and Title V, including EPA's interpretation of section
129(e), information on updating existing Title V permit applications
and reopening existing Title V permits, see the final ``Federal Plan
for Commercial and Industrial Solid Waste Incineration,'' October 3,
2003 (68 FR 57518), as well as the ``Summary of Public Comments and
Responses'' document in the OSWI docket (EPA-HQ-OAR-2003-0156).

I. What are the applicability dates of the standards?

    New SSI units that commence construction after October 14, 2010, or
that are modified 6 months or more after the date of promulgation, must
meet the NSPS emission limits of 40 CFR part 60, subpart LLLL within 6
months after the promulgation date of the standards or upon startup,
whichever is later.
    Under the final EG, and consistent with CAA section 129 (b)(2) and
40 CFR 60, subpart B, states are required to submit state plans
containing the existing source emission limits of subpart MMMM of this
part, and other requirements to implement and enforce the EG within 1
year after promulgation of the EG. States must submit state plans to
EPA by March 21, 2012. State plans apply to existing SSI in the state
(including SSI that are modified prior to and including the date 6
months after promulgation) and must be at least as protective as the
EG.
    The final EG requires existing SSI to demonstrate compliance with
the 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 EG, whichever is earlier.
Consistent with CAA section 129, EPA expects states to require
compliance as expeditiously as practicable. However, because we believe
that many SSI units will find it necessary to retrofit existing
emissions control equipment and/or install additional emissions control
equipment in order to meet the final limits, EPA anticipates that
states may choose to provide the 3-year compliance period allowed by
CAA section 129(f)(2). If EPA does not approve a state plan or issue a
Federal plan, then the compliance date is 5 years from the date of the
final rule.
    EPA intends to develop a Federal plan that will apply to existing
SSI units in any state that has not submitted an approved state plan
within 2 years after promulgation of the EG. The final EG allows
existing SSI units subject to the Federal plan up to 5 years after
promulgation of the EG to demonstrate compliance with the standards, as
allowed by CAA section 129(b)(3).

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

    EPA must have performance test data to conduct effective reviews of
CAA sections 112 and 129 standards, as well as for many other purposes
including compliance determinations, emission factor development, and
annual emission 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 a step to improve data
accessibility and increase the ease and efficiency of reporting for
sources. Owners and operators of SSI facilities are required to submit,
to EPA's ERT database, electronic copies of reports of certain
performance tests required under the SSI EG and NSPS. Data entry will
be through an electronic emissions test report structure called the
Emissions Reporting Tool (ERT) whenever conducting performance tests.
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 that perform field test
assessments. The ERT is currently available at http://www.epa.gov/ttn/chief/ert/ert_tool.html, and access to direct data submittal to EPA's
electronic emissions database (WebFIRE) will become available by
December 31, 2011.
    The requirement to submit source test data electronically to EPA
would not require any additional performance testing and would apply to
those performance tests conducted using test methods that are supported
by the 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 the ERT. In addition, when a facility submits performance test data
to WebFIRE, there will be no additional requirements for emissions test
data compilation. Moreover, we believe industry will benefit from
development of improved emission 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 submitting source test data through the ERT
is a standardized method to compile and store much of the documentation
required to be reported by this rule that also clearly states what
testing information would be required. Another important benefit of
submitting these data to EPA at the time the source test is conducted
is that it should substantially reduce the effort involved

in data collection activities in the future. When EPA has source
category performance test data in hand, there will likely be fewer or
less substantial data collection requests in conjunction with
prospective required residual risk assessments or technology reviews.
This results in a reduced burden on both affected facilities (in terms
of reduced manpower to respond to data collection requests) and EPA (in
terms of preparing and distributing data collection requests and
assessing the results).
    State/local/tribal agencies may also benefit in that their review
may be more streamlined and accurate because they 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 will greatly improve the overall
quality of the existing and new emission factors by supplementing the
pool of emissions test data upon which the emission factor is based and
by ensuring that data are more representative of current industry
operational procedures. A common complaint heard 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 will ensure that emissions factors, when
updated, represent accurately the most current range of operational
practices. In summary, in addition to supporting regulation
development, control strategy development, and other air pollution
control activities, receiving test data already collected and using
them in the emissions factors development program will save industry,
state/local/tribal agencies, and EPA significant time, money, and
effort while improving the quality of emission inventories and related
regulatory decisions.
    As mentioned earlier, the electronic database that will be used is
EPA's WebFIRE, which is a Web site accessible through EPA's TTN Web.
The WebFIRE Web site was constructed to store emissions test data for
use in developing emission factors. A description of the WebFIRE
database can be found at http://cfpub.epa.gov/oarweb/index.cfm?action=fire.main. The ERT will be able to transmit the
electronic report 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.

IV. Summary of Significant Changes Following Proposal

    EPA received over 90 public comments on the proposed rulemaking.
Furthermore, we conducted one public hearing to allow the public to
comment on the proposed rulemaking. After consideration of public
comments received, EPA is making several changes to the standards.
Following are the major changes to the standards since the proposal.
The rationale for these and any other significant changes can be found
in section V of this preamble or in the ``Sewage Sludge Incineration
(SSI) Rule: Summary of Public Comments and Responses'' in the SSI
docket (EPA-HQ-OAR-2009-0559).

A. Applicability

    The final rule clarifies that, if any amount of sewage sludge is
burned in an incinerator at a wastewater treatment facility designed to
treat domestic sewage sludge, the incinerator is subject to the SSI
standards in subparts LLLL and MMMM of this part while burning sewage
sludge. The final rule also clarifies that sewage sludge that is not
burned in a SSI located at a wastewater treatment facility designed to
treat domestic sewage sludge is subject to other section 129 standards,
such as the CISWI standards (40 CFR part 60, subparts CCCC and DDDD of
this part), the OSWI standards (40 CFR part 60, subparts EEEE and
FFFF), the MWC standards (40 CFR part 60, subparts Ea, Eb, Cb, AAAA,
and BBBB of this part) or the Hazardous Waste Combustor rule (40 CFR
part 63 subpart EEE).

B. Subcategories

    The proposed NSPS did not subcategorize new sources. In the final
NSPS, SSI units at new sources are subcategorized into two
subcategories: MH and FB.

C. MACT Floor UPL Calculation and EG and NSPS Emission Limits

    At proposal, we used a 99 percent UPL calculation to determine
variability. For the final rule, for existing FB units, we are using a
weighted 99 percent UPL calculation to account for the biasing of
emissions data from one facility. The weighted UPL was not used for MH
units.
    In the proposed rule, two statistical measures, skewness and
kurtosis, were examined to determine if the data used to calculate the
MACT floor were normally or log-normally distributed. If both the
reported values and the natural-log transformed reported values had
skewness and kurtosis statistics that indicated neither were normally
distributed, the reported dataset was selected as the basis of the
floor to be conservative. If the results of the skewness and kurtosis
hypothesis tests were mixed for the reported values and the natural
log-transformed reported values, the analysis done on the reported data
values was chosen to be conservative. We have modified our assumptions
when results of the skewness and kurtosis tests do not clearly show
whether a normal or log-normal distribution better represents the data,
or when there are not enough data to complete the skewness and kurtosis
tests. In these cases, we have chosen to use the log-normal results for
the final MACT floor calculation.
    In the proposed rule, we proposed setting beyond-the-floor emission
standards for Hg emissions from existing MH units. In the final rule,
we are establishing MACT floor emission limits but are not setting
beyond-the-floor standards. Also, we are not finalizing the proposed
opacity limits. At proposal, we set emission limits for both PCDD/PCDF
TMB and PCDD/PCDF TEQ and required SSI units to meet both limits. In
the final standards, we are allowing affected sources to comply with
either the PCDD/PCDF TMB or TEQ emission limits.
    In the proposed rule, we did not compare the CO span of the test to
the measured CO values to determine if the values were consistent. For
the final rule, we reviewed the CO values obtained from emission test
reports to determine whether the span of the test used was capable of
accurately reading the reported value. If the span was inconsistent
with the reported value, the CO levels were adjusted to provide a value
that was more consistent with the span. We revised the CO limits based
on the results of this analysis.
    The final emission limits resulting from the revised MACT floor
calculations are presented in Tables 3 through 6 of this preamble, and
compared to the proposed emission limits.

                      Table 3--Final and Proposed Emission Limits for Existing FB SSI Units
----------------------------------------------------------------------------------------------------------------
                                                                                Proposed       Final emission
                  Pollutant                                Units               emission limit         limit
----------------------------------------------------------------------------------------------------------------
Cd..........................................  mg/dscm @ 7% O2...............            0.0019            0.0016
CO..........................................  ppmvd @ 7% O2.................                56                64
HCl.........................................  ppmvd @ 7% O2.................              0.49              0.51
Hg..........................................  mg/dscm @ 7% O2...............            0.0033             0.037
NOX.........................................  ppmvd @ 7% O2.................                63               150
Pb..........................................  mg/dscm @ 7% O2...............            0.0098            0.0074
PCDD/PCDF, TEQ..............................  ng/dscm @ 7% O2...............             0.056              0.10
PCDD/PCDF, TMB..............................  ng/dscm @ 7% O2...............              0.61               1.2
PM..........................................  mg/dscm @ 7% O2...............                12                18
SO2.........................................  ppmvd @ 7% O2.................                22                15
----------------------------------------------------------------------------------------------------------------

                      Table 4--Final and Proposed Emission Limits for Existing MH SSI Units
----------------------------------------------------------------------------------------------------------------
                                                                                Proposed       Final emission
                  Pollutant                                Units               emission limit         limit
----------------------------------------------------------------------------------------------------------------
Cd..........................................  mg/dscm @ 7% O2...............             0.095             0.095
CO..........................................  ppmvd @ 7% O2.................             3,900             3,800
HCl.........................................  ppmvd @ 7% O2.................               1.0               1.2
Hg..........................................  mg/dscm @ 7% O2...............              0.02              0.28
NOX.........................................  ppmvd @ 7% O2.................               210               220
Pb..........................................  mg/dscm @ 7% O2...............              0.30              0.30
PCDD/PCDF, TEQ..............................  ng/dscm @ 7% O2...............              0.32              0.32
PCDD/PCDF, TMB..............................  ng/dscm @ 7% O2...............               5.0               5.0
PM..........................................  mg/dscm @ 7% O2...............                80                80
SO2.........................................  ppmvd @ 7% O2.................                26                26
----------------------------------------------------------------------------------------------------------------

                        Table 5--Final and Proposed Emission Limits for New FB SSI Units
----------------------------------------------------------------------------------------------------------------
                                                                                Proposed       Final emission
                  Pollutant                                Units               emission limit         limit
----------------------------------------------------------------------------------------------------------------
Cd..........................................  mg/dscm @ 7% O2...............           0.00051            0.0011
CO..........................................  ppmvd @ 7% O2.................               7.4                27
HCl.........................................  ppmvd @ 7% O2.................              0.12              0.24
Hg..........................................  mg/dscm @ 7% O2...............            0.0010            0.0010
NOX.........................................  ppmvd @ 7% O2.................                26                30
Pb..........................................  mg/dscm @ 7% O2...............           0.00053           0.00062
PCDD/PCDF, TEQ..............................  ng/dscm @ 7% O2...............            0.0022            0.0044
PCDD/PCDF, TMB..............................  ng/dscm @ 7% O2...............             0.024             0.013
PM..........................................  mg/dscm @ 7% O2...............               4.1               9.6
SO2.........................................  ppmvd @ 7% O2.................               2.0               5.3
----------------------------------------------------------------------------------------------------------------

                        Table 6--Final and Proposed Emission Limits for New MH SSI Units
----------------------------------------------------------------------------------------------------------------
                                                                                Proposed       Final emission
                  Pollutant                                Units               emission limit         limit
----------------------------------------------------------------------------------------------------------------
Cd..........................................  mg/dscm @ 7% O2...............           0.00051            0.0024
CO..........................................  ppmvd @ 7% O2.................               7.4                52
HCl.........................................  ppmvd @ 7% O2.................              0.12               1.2
Hg..........................................  mg/dscm @ 7% O2...............            0.0010              0.15
NOX.........................................  ppmvd @ 7% O2.................                26               210
Pb..........................................  mg/dscm @ 7% O2...............           0.00053            0.0035
PCDD/PCDF, TEQ..............................  ng/dscm @ 7% O2...............            0.0022            0.0022
PCDD/PCDF, TMB..............................  ng/dscm @ 7% O2...............             0.024             0.045
PM..........................................  mg/dscm @ 7% O2...............               4.1                60
SO2.........................................  ppmvd @ 7% O2.................               2.0                26
----------------------------------------------------------------------------------------------------------------

D. Baseline Emissions, Costs and Impacts Estimation

    For the final rule, we have revised the baseline emissions, costs,
and impacts to incorporate information provided by commenters. A
discussion of the changes is presented in section V of this preamble.
The results of these analyses are summarized in section VI of this
preamble.

E. Compliance Requirements

    For both the standards, the following changes have been made:
     SSI units must submit (at least 60 days before their
initial compliance test date) a monitoring plan to establish that

their ash handling system will meet the visible emissions limit on a
continuous basis.
     The alternative to test less frequently (every third year)
is being revised to be the following:
    [cir] If SSI units demonstrate emissions below a specified
threshold during two consecutive performance tests, they may test every
3 years instead of annually. Any year that the emission threshold is
not met, the SSI must test annually until the threshold is met over a
consecutive 2 year period. The alternative in the standards no longer
requires that SSI units establish that they meet the lower thresholds
for three consecutive years.
    [cir] For all pollutants, less frequent testing is allowed if
emissions are no greater than an emissions threshold of 75 percent of
the emission limit.
    [cir] For fugitive emissions from ash handling, less frequent
testing is allowed as long as visible emissions of combustion ash occur
less than or equal to two percent of each hourly observation period
(the standard is five percent of each of three hourly observation
periods).
     The final rule removes the requirements in the standards
to maintain sludge feed rate and moisture content within specified
parameters. However, sludge feed rate and sludge moisture content are
still required to be monitored during performance test runs, and daily
records of sludge feed rate and sludge moisture content are required to
be kept.
     At proposal, operating limits were calculated based on a
specified percentage of the average parameter value recorded during
pollutant performance tests. In the final standards, operating
parameter limits are determined on a site-specific basis as the minimum
or maximum operating parameter value for the parameter, as applicable,
recorded during pollutant performance tests.
     The proposed standards schedule for conducting annual
performance tests was each 10-12 months. This has been changed to
specify that performance tests must be conducted on a calendar year
basis (no less than nine calendar months and no more than 15 calendar
months following the previous performance test); and you must complete
five performance tests for each such pollutant in each 5-year calendar
period.
     The averaging time for demonstrating compliance with the
CO CEMS operating parameters has been changed from a 4-hour rolling
averaging period to a 24-hr block averaging period. The averaging times
for all other operating parameters, except scrubber liquid pH, has been
changed from a 4-hour rolling averaging period to a 12-hour block
averaging period.
     During each compliance test run, SSI units must be
operated at a minimum of 85 percent of their maximum permitted
capacity.

F. Definitions

    The following definitions have been revised:
     Process change means a significant permit revision, but
only with respect to those pollutant-specific emission units for which
the proposed permit revision is applicable, including but not limited
to:
    (1) A change in the process employed at the wastewater treatment
facility associated with the affected SSI unit (e.g., the addition of
tertiary treatment at the facility, which changes the method used for
disposing of process solids and processing of the sludge prior to
incineration).
    (2) A change in the air pollution control devices used to comply
with the emission limits for the affected SSI unit (e.g., change in the
sorbent used for activated carbon injection).
     Sewage sludge incineration (SSI) unit means an
incineration unit combusting sewage sludge for the purpose of reducing
the volume of the sewage sludge by removing combustible matter. Sewage
sludge incineration unit designs include fluidized bed and multiple
hearth. A SSI unit also includes, but is not limited to, the sewage
sludge feed system, auxiliary fuel feed system, grate system, flue gas
system, waste heat recovery equipment, if any, and bottom ash system.
The SSI unit includes all ash handling systems connected to the bottom
ash handling system. The combustion unit bottom ash system ends at the
truck loading station or similar equipment that transfers the ash to
final disposal. The SSI unit does not include air pollution control
equipment or the stack.

V. Significant Public Comments and Rationale for Changes to the
Proposed Rule

    This section contains a brief summary of major comments and
responses. EPA received many comments on this subpart covering numerous
topics. EPA's responses to all comments, including those below, can be
found in the comment response document for SSI units in the docket.

A. Legal and Applicability Issues Regulating SSI Under Section 112 vs.
Section 129

    Comment: Many commenters contended that SSI are within the CWA
definition of POTW; therefore, according to CAA section 112(e)(5), EPA
must regulate SSI units under CAA section 112(d), and not CAA section
129. The commenters emphasized that SSI units are located within each
respective POTW and are wholly integrated into the solids handling and
treatment processes at each POTW.
    Other commenters stated that SSI units cannot be regulated under
CAA section 129 because they are combusting material that is generated
by the POTW, which is neither a commercial or industrial establishment
nor the general public as required in CAA section 129(g)(1). The
commenters added that, based on the proposed definition of solid waste,
even if they had a new point of generation within the POTW where they
were generating solid waste, the POTW sewage sludge is from a municipal
source and does not pass the broad applicability for solid waste
incineration under CAA section 129. Another commenter added that CAA
section 129(a)(1)(B)-(C) also directs EPA to set standards for solid
waste incineration units combusting municipal waste, but to qualify as
a unit combusting municipal waste, the unit must first be a solid waste
incineration unit. The commenters concluded that this would not include
SSI units.
    Several commenters stated that EPA's determination to regulate SSI
units under CAA section 129 contradicts previous decisions where EPA
has stated that regulations were being developed for SSI under CAA
section 112. Another commenter stated that EPA's revision to the list
of source categories under CAA section 112 to delete SSI units was
because there were no major sources in the source category. One
commenter added that EPA's decision to regulate SSI units under CAA
section 129 is based on an overly broad reading of the NRDC case. The
commenter also claimed that SSI units are not within the scope of the
definition of ``solid waste incineration unit'' in section 129 because
sewage sludge is not generated by a commercial or industrial
establishment or by the general public.
    Response: EPA disagrees with the commenter's assertion that
regulation of SSI units under section 129 is inconsistent with past EPA
statements. As explained in the NPRM, EPA issued emissions standards
for POTW in 1999 pursuant to section 112(d), and those emissions
standards did not include standards for SSI units. In the proposed POTW
emissions standards, EPA stated that ``[s]ewage sludge incineration
will be regulated under section 129 of the CAA[.]'' See 63 FR 66087
(December 1,

1998). EPA also explained in the NPRM for today's action that the EPA's
statements regarding SSI units during its promulgation of emissions
standards for OSWI units are squarely in conflict with the Court's
decision in NRDC v. EPA, 489 F.3d 1250 (D.C. Cir. 2007), which states
in pertinent part that any unit that combusts any solid waste at all is
subject to CAA section 129. The commenter does not appear to disagree
with that conclusion, but instead simply argues that EPA cannot
regulate SSI units under section 129 because it previously stated that
it would regulate them under section 112. However, the NRDC decision
precludes EPA from doing so. Additionally, section 112(c)(6) requires
that EPA promulgate emission standards assuring that sources accounting
for not less than 90 percent of the aggregate emissions of each of the
HAP identified in section 112(c)(6) are subject to emission standards.
EPA has determined that section 129 source categories can be included
to meet our 90 percent obligations. Therefore, EPA has included SSI
units in the section 112(c)(6) list of sources because SSI units are
need to meet our 90 percent requirement for mercury. This decision is
documented in the memorandum ``Emission Standards for Meeting the
Ninety Percent Requirement under Section 112(c)(6) of the Clean Air
Act'' in the SSI docket (EPA-HQ-OAR-2009-0559)
    Moreover, section 112(e)(5) does not require EPA to issue emissions
standards for SSI units under section 112(d). Rather, it simply governs
the schedule for the issuance of section 112(d) emissions standards for
POTW. Section 112(e), titled ``Schedule for Standards and Review,''
generally requires EPA to establish emissions standards for initially
listed source categories as expeditiously as practicable, with certain
specific deadlines in section 112(e)(1). Section 112(e) further
describes how EPA shall prioritize source categories for regulation,
and requires EPA to establish a schedule for issuance of emissions
standards for section 112 listed source categories. Finally, Congress
specified a different schedule for POTW in section 112(e)(5), stating
that emissions standards shall be issued no later than November 15,
1995. Thus, section 112(e)(5) does not require EPA to regulate SSI
units under section 112(d), but rather simply identifies the date by
which EPA must issue emissions standards for POTW.
    Additionally, the commenter's interpretation of section 112(e)(5)
would conflict with section 129(g) and with the DC Circuit's
interpretation of section 129(g) as explained in NRDC v. EPA. Section
129(g) defines ``solid waste incineration unit'' to include any unit
combusting any solid waste, and the Court in NRDC v. EPA rejected EPA's
position that it could choose to regulate certain units, combusting
solid waste, under section 112 instead of under section 129. Since SSI
units do combust solid waste, EPA does not have the discretion under
section 129 to create an exemption for SSI units from the statutory
definition of solid waste. The court noted that section 129(g) itself
specifies certain units that combust solid waste but are exempt from
the definition, and noted that where Congress created such enumerated
exemptions, the EPA lacks discretion to create additional ones.
    EPA also disagrees with the commenter that SSI units do not combust
waste from the general public. Sewage sludge clearly originates from
the general public, including residential and commercial facilities.
Simply because the waste is treated at a POTW prior to combustion does
not change the original source of the sewage sludge. The commenter
refers to a statement in EPA's 2000 Unified Regulatory Agenda to
support its argument. However, the Regulatory Agenda did not represent
an Agency interpretation following a notice and comment process.
Moreover, as explained above, EPA's position regarding the section of
the Act under which SSI units must be regulated has changed since 2000,
in light of the DC Circuit's decision in NRDC v. EPA. Finally, EPA
notes that its final action on reconsideration of the OSWI rule did not
refer to the source of sewage sludge as a basis for concluding that
regulation under section 129 was not required. Instead, as explained
above, it referred to discretion the Agency believed it had at the time
to choose to regulate certain solid waste incinerators under section
112--discretion the Agency no longer believes it has.
    The commenter's reference to statements made in other Federal
Register notices that pre-date the NRDC decision similarly fail to
support its argument that EPA must regulate SSI units under section
112. Specifically, commenters refer to EPA's inclusion of SSI on the
list of area source categories listed under section 112(c)(3) and
(k)(3)(B)(ii) of the Act. See 67 FR 70427 (Nov. 22, 2002). However,
that listing does not lead to the conclusion that SSI must be regulated
under section 112. First, as explained above, EPA's interpretation of
its authority to regulate SSI has changed following the issuance of the
DC Circuit's decision in NRDC v. EPA, which occurred after the 2002
listing referred to by the commenter. Additionally, that listing
included source categories that would clearly be regulated under
section 129, such as medical waste incinerators and municipal waste
combustors, Id. at 70428, because EPA's regulation of incinerator
source categories under section 129 serves towards meeting its
statutory obligations under section 112(c)(3) and (k)(3)(B)(ii).
Therefore, the inclusion of SSI on that list does not indicate that
such units must be regulated under section 112.
    EPA further disagrees that regulation of SSI units under section
129 is unnecessary because SSI units are already regulated under
section 405 of the CWA and that section 129 regulation will therefore
provide no public health or environmental benefit. As explained in
section VI of this preamble, today's action will benefit public health
and the environment by achieving reductions of the section 129
pollutants from SSI units beyond those required by regulations issued
pursuant to the CWA. Today's action must be undertaken to comply with
the Clean Air Act and the court decision in NRDC v. EPA. EPA further
notes that section 405 of the CWA expressly provides that nothing in
that section is intended to waive more stringent requirements of any
other law. Therefore, Congress clearly did not intend for regulation of
SSI units under the CWA to preclude any other regulations, including
regulation under CAA section 129. Overlap with Other Standards
    Comment: Several commenters expressed concern that other types of
solid waste incineration units could be considered SSI units and
subject to the SSI standards if they combust any amount of sewage
sludge. Some commenters added that the definition of a SSI does not
have a de minimis level of sewage sludge burned. Other commenters
requested clarification on whether SSI units burning non-sludge
industrial waste would be subject to both SSI and CISWI. Some
commenters suggested that SSI units be consistent with the MWC
standards and provide an exemption for co-fired combustors firing 30
percent or less by weight of sewage sludge.
    Commenters suggested that the SSI standards provide exclusions for
all solid waste incineration units that meet the applicability
requirements of other CAA section 129 standards, including MWCs
regulated under Subparts Ea, Eb, Cb, AAAA, and BBBB. The commenters
noted that the CISWI standards specifically exempted MWC units and
other units subject to CAA section 129 standards.

    Several commenters contended that EPA should exempt incineration
units subject to hazardous waste combustor regulations and/or hazardous
waste management permits under the Solid Waste Disposal Act. The
commenters added that CAA section 129(g)(1) states that a solid waste
incineration unit does not include incinerators or other units required
to have a permit under section 3005 of the SWDA. Other commenters
requested EPA include an exemption for hazardous waste combustion units
that are affected sources under 40 CFR part 63 subpart EEE.
    Response: Section 129 defines solid waste incineration unit to
include any unit combusting any solid waste. Therefore, EPA is not
setting de minimus levels for solid waste burned in incinerators. An
incinerator located at a wastewater treatment facility designed to
treat domestic sewage sludge that combusts any amount of sewage sludge
is subject to the final SSI standards. We have clarified that the final
standards and guidelines do not apply to sewage sludge that is not
burned in a SSI located at a wastewater treatment facility designed to
treat domestic sewage sludge. Sewage sludge that is not burned in a SSI
located at a wastewater treatment facility designed to treat domestic
sewage sludge is subject to other section 129 standards, such as the
CISWI standards (40 CFR part 60, subparts CCCC and DDDD of this part),
the OSWI standards (40 CFR part 60, subparts EEEE and FFFF), the MWC
standards (40 CFR part 60, subparts Ea, Eb, Cb, AAAA, and BBBB of this
part) or the Hazardous Waste Combustor rule (40 CFR part 63 subpart
EEE).
    Hazardous waste combustion units that are required to have a permit
under CAA section 3005 or the Solid Waste Disposal Act are exempt from
CAA section 129 standards per CAA section 129(g)(1), therefore we do
not believe an exemption is needed for this rule.
    Comment: Several commenters objected to EPA issuing the proposed
SSI standards prior to making determinations regarding the definition
of non-hazardous solid waste.
    Response: EPA is not making determination in this rule about the
definition of non-hazardous solid waste. Section 129 of the CAA states
that ``solid waste'' shall have meaning promulgated by the
Administrator under RCRA. Therefore, today's action is consistent with
using the defintion of non-hazardous secondary materials promulagted
RCRA rule, elsewhere in today's Federal Register.
    Comment: Several commenters contended that sewage sludge is not a
solid waste, as the CAA defines solid waste by referencing the
definition of solid waste under RCRA. The commenters added that RCRA
excludes sewage sludge in what is commonly referred to as the domestic
sewage exclusion (DSE). The exclusion explicitly states that solid
waste does not include solid or dissolved material in domestic sewage.
    Response: This comment is not relevant to EPA's establishment of
emissions standards for SSI units. Rather, it is relevant to EPA's
proposed Identification of Non-Hazardous Secondary Materials That Are
Solid Waste rule, and is addressed in EPA's final action on that
proposed rule.

B. Subcategories

    Comment: Many commenters agreed with the development of separate EG
for existing MH and FB units. The commenters also requested adding the
same subcategories for the NSPS. The commenters added that it was
inappropriate to consider the best performing FB SSI as the best
performing similar source for the MH SSI new source category. They also
stated that, as proposed, the NSPS standards would discourage a POTW's
ability to modify existing MH units, including modifications to improve
combustion efficiency or boost steam output for electricity generation.
Some commenters stated that, by using the best performing FB unit as
the basis for the NSPS for MH units, EPA was effectively setting a
beyond-the-floor MACT limit for SSI units without considering any
criteria that the statute requires. Other commenters agreed with the
decision to use the best-performing FB unit as the best similar source
for the MH SSI source category.
    Other commenters requested further subcategorization based on size
of the SSI unit, type of sewage sludge incinerated, limited use units,
and distance over which the SSI would need to transport its sludge for
disposal.
    Response: We have considered the commenters' concerns and are
setting separate standards for FB and MH units at new sources in the
final rule. As discussed in the NPRM, there are two types of
incinerators currently used to combust sewage sludge: MH and FB
incinerators. The differences between the two combustor designs result
in significant differences in emissions, size of the flue gas stream,
ability to handle variability in the feeds, control of temperature and
other process variables, auxiliary fuel use and other characteristics.
To reflect the differences in their combustion mechanisms, two
subcategories, FB and MH, were developed in the NPRM for new and
existing SSI sources.
    At proposal for the MH new source subcategory, we considered the
best-performing FB incinerator to be the best-performing similar source
because we were not aware of any new MH sources that have been
constructed in the last 20 years, and information provided by the
industry indicates that future units that will be constructed are
likely to be FB incinerators.
    We have re-evaluated our decision. Although few MH units have been
constructed over the last 20 years, there is no technical reason that
would preclude a source from constructing a MH unit. The same design
differences that distinguish existing FB and MH units also apply to new
units, and provide a similar basis for subcategorizing between the two
types of units. Therefore, we are setting separate standards for MH
units at new and reconstructed sources. Such subcategorization is
appropriate based on the differences between FB and MH units described
above, and will also serve to ensure that MH units do not avoid making
modifications that may require them to meet standards based on FB
units. We are not subcategorizing SSI units on any other basis because
we do not have data to support distinguishing units based on class,
type, or size. Without such information, we do not have a basis for
concluding that these types of units should be placed in a different
subcategory.

C. MACT Floor Analysis

Pollutant-by-Pollutant Approach
    Comment: Many commenters objected to setting the MACT floors using
a pollutant by pollutant approach because none of the facilities in
EPA's database can simultaneously meet all the proposed standards. One
commenter stated that EPA's MACT Floor methodology is supposed to
involve ``review of actual emissions data with an appropriate
accounting for emissions variability''. However, the commenter
contended that EPA fails to follow this guidance in a practical manner
in establishing MACT Floors for SSI units and that this results is
unrealistically stringent limits that are not achievable for any SSI.
Several commenters noted that this was especially true for the new
source standards. Several commenters added that EPA's pollutant-by-
pollutant basis violates the statute and its own views of the statute.
One commenter stated that if EPA cannot demonstrate that the top
performers can simultaneously meet all standards, EPA has improperly
circumvented the

section 129 for establishing ``beyond-the-floor'' standards because the
``floor standards would force industry-wide technological upgrades
without consideration of the factors (cost and energy in particular)
which Congress mandated for consideration when establishing beyond-the-
floor standards.''
    Many commenters specifically mentioned that EPA's pollutant-by-
pollutant, lowest emission methodology for setting the CO and
NOX standards is flawed because EPA did not take into
account the inherent conflict in complying with two standards. The
commenters noted that CO and NOX emissions are inversely
proportional. The commenters explained that decreases in CO tend to
elevate NOX and vice versa. The commenters added that high
temperature combustion with long residence times and high oxygen
concentration results in very low CO emissions, and that those same
operating conditions favor high NOX emissions. The
commenters added that the conditions used to minimize CO (i.e., high
temperature afterburners) consume more fuel and produce more
CO2 emissions.
    One commenter noted that the SSI unit with the most advanced
control technologies, and those EPA indicated were costed in the
impacts analysis, would not meet the emission limits for all of the
pollutants all of the time. The commenter provided an example showing
that of 11 of 30 test data points from the SSI unit in EPA's database
would not comply with the Cd standard, 28 of 30 data points would not
comply with the Pb standard, 22 of 30 would not comply with the HCl
standard, six of six data points would not comply with the PCDD/PCDF
TMB or TEQ, 86 of 105 would not comply with the CO standard, and eight
of 15 would not comply with the NOX standard. The commenter
concluded that data variability has not been appropriately accounted
for and that EPA's method of establishing the MACT floor based on the
best performing unit for each pollutant is not reasonable.
    Response: We disagree with the commenters who object to setting
MACT floors on a pollutant-by pollutant basis. 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).
    EPA interprets the provision in CAA section 129(a)(2) 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.
    The rest of CAA section 129 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)* * *.'' (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: PM (total and
fine), opacity (as appropriate), sulfur dioxide, hydrogen chloride,
oxides of nitrogen, carbon monoxide, lead, Cd, mercury, and dioxins and
dibenzofurans.'' Thus, the statute requires EPA to set individual
numeric performance standards based on the maximum degree of reduction
in emissions actually achieved 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 emission levels achieved for each 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.
    Looking at the statute as a whole, EPA declared in the 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 subsection 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 repeated that EPA must 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 (September 20,
1994) (municipal waste combustors). In addition, such an approach has
been upheld in other contexts. See, e.g., Chemical Mfrs. Ass'n v. EPA,
870 F.2d 177, 239 (5th Cir. 1989) (concluding that basing CWA best
available technology standards on a pollutant-by-pollutant basis was a
rational interpretation of EPA's obligations under that similar
statute). We 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 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. See 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 CDD/CDF 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. Sierra Club v. EPA (Copper Smelters), 353 F.3d 976, 979-80 (DC
Cir. 2004).

    The fact that the statute does not contain the phrase ``for each
pollutant'' 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 emission
limitations in this rule reflect actual performance and are 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).
    Commenters made much of the fact that no single facility is
presently achieving all of the nine pollutant limits proposed. However,
the available information compared to the final standards disputes this
assertion. For the final standards, based on the data we have, our
estimate of baseline emissions, and the revised emission limits, we are
estimating that 155 of 204 existing SSI units can meet standards for
all nine pollutants, without installing additional pollution control.
We cannot make this assessment for new sources, because none have been
constructed. However, we are not aware of any technical reason that new
units could not install the most advanced pollution control techniques
or reduce the pollutant concentrations in the sludge to meet the new
source standards.
    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 what would result under a
unit-based methodology. We interpret CAA section 129 to require that
the MACT floor be determined 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 SSI
facility to determine whether combustion conditions can be adjusted to
meet both standards and, if not, install NOX controls as
necessary (e.g., SNCR systems, SCR systems, FGR, or low NOX
burners). In the proposed rule, we conjectured reasons why SCR and SNCR
were not used or may not be able to be used at SSI units. While we are
not aware of any SSI unit that currently uses SNCR or SCR, we also do
not know of technical reason why they could not be used. Given the
limited data available on SSI units with FGR, we could not definitely
determine how effective the technology was on SSI units. However, we
also do not know of a technical reason why they could not be used, if
necessary, to meet NOX limits, and commenters did not
provide any reasons they could not be used.
Dataset for the MACT Floor Analysis
    Comment: Many commenters urged EPA to collect more information to
set the standards. Many commenters contended that EPA does not have
sufficient actual emission data from enough SSI units to properly set
the MACT floor. Some commenters contended that the floor-setting
provision in section 129 requires them to set the existing floor
standards ``based on the best performing 12 percent of sources in the
category'' and not just based on the sources for which they have
information. The commenters contended that EPA did not have emissions
data from the best-performing 12 percent of sources or even from 12
percent of sources. Additionally, the commenters stated that there is
no evidence that the sources for which EPA collected data are among the
top 12%. One commenter added that EPA is using actual data from as
little as 4.3 percent of a subcategory (7 of 163 MH units for HCl) to
determine how the top 12 percent perform.
    Some commenters contended that EPA chose to limit its ICR to just
nine entities because collecting information from ten or more entities
would have triggered the PRA obligations and a more rigorous OMB
review. The commenters concluded that EPA's plan to circumvent the PRA
and OMB review resulted in an inadequate dataset for this rulemaking
that leaves EPA unable to reliably take the first necessary step in a
section 129 rulemaking: To determine which of the SSI units are the
best performing sources.
    Some commenters also contended that EPA targeted its ICR to the
nine POTW expected to have the lowest emissions based on the type of
unit and the installed air pollution controls. The commenters contended
that EPA's targeted approach to collecting data from expected top
performers undermines its ability to presume the data is a random
sample representative of the entire source category or subcategory. The
commenters stated that if the data gathered are not representative at
the outset, then the data cannot reliably be used in a statistical
equation to predict the emissions data across the source category or
subcategory.
    Some commenters noted that in the past, EPA has used permit or
other regulatory limits, emission levels, feed rate control, and other
information to establish MACT standards. Despite this flexibility, the
commenters stated that EPA is proposing to use an ``actual emissions''
method in the SSI rule, even though it does not have actual emissions
for each of the regulated pollutants from at least 12% of the units.
    Another commenter stated that EPA used emission data from state
databases for an additional nine MHs. The commenter stated that EPA was
instructed by the Court to collect data from the best-performing 12% of
existing sources, and EPA needs to justify that the emissions data from
the state databases for the additional nine MHs were the 12% best
performing MHs.
    Response: As explained in the preamble to the proposed rule, EPA
requested several SSI to conduct emissions testing and provide the
results to EPA for purposes of this rulemaking. Specifically, EPA
collected information on the best-performing sources to establish MACT
floor standards for SSI. Therefore, EPA sent emissions tests requests
under section 114 of the CAA to nine entities that own and operate SSI
units. EPA identified SSI units that were expected to be the best-
controlled sources and the best performers for further emissions
testing. The Agency acknowledges that this selection methodology
targets identifying the best-performing sources rather than selecting a
representative sample of sources. However, given the court-ordered
deadline for EPA to issue the final SSI rule, it was not possible to
undertake the time-consuming process of sending an ICR to all the
affected SSI units consistent with the requirements of the PRA.

    To select the surveyed owners, EPA reviewed the inventory of SSI
units for the control devices being operated, and identified a subset
of units expected to have the lowest emissions based on the type of
unit and the installed air pollution controls. These controls generally
achieve the most reductions possible for the CAA section 129
pollutants, and thereby allow EPA to identify for each pollutant the
units with the lowest emissions. For example, units were selected that
operated more than one of the following technologies: Activated carbon
injection to reduce Hg and dioxins/furans; RTOs or afterburners to
reduce CO and organics; wet ESP to reduce fine particulate; high
efficiency scrubbers such as packed bed scrubbers and impingement tray
scrubbers to reduce PM, Cd, Pb, particulate Hg, and acid gases such as
HCl and SO2; and units with multiple control devices that
could reduce PM, Cd, Pb, particulate Hg, such as venturi scrubber in
combination with impingement scrubbers and wet ESPs or with another
particulate control device. The 9 owners or operators selected were
from different states in different regions of the country, providing a
wide spectrum of sources for sludge generated.
    Six of the nine ICR recipients operate MH units, resulting in 13 MH
units surveyed. Three of the nine operate FB units, resulting in 7 FB
units surveyed. Some owners of multiple units at a facility provided
information for less than the total number they operated, e.g. 1 unit
instead of 2, because not all units were in operation during the test
period. Of those 20 units from the nine surveyed municipalities, EPA
collected data from 17 units that were in operation (11 MH units and 6
FB units). While testing was being undertaken, the EPA also collected
emission test information for 9 MH SSI units collected from state
environmental agencies public databases. For some pollutants, the
emissions from these supplemental test reports were lower than those
from the nine ICR sources. The EPA concluded that it was appropriate to
use all the emissions information from these test reports in the MACT
floor analysis. The EPA also collected many test reports that were
older than 15 years. The older reports were determined to not be
appropriate for this rulemaking because they were unlikely to represent
current emissions performance, due to their age and because they pre-
dated required compliance with the CWA part 503 standard. In total,
emissions information were collected from 6 FB units and 20 MH units
from facilities responding to the ICR and additional test reports
provided by state environmental agencies.
    As discussed in the NPRM and background documentation, the EPA
conducted a statistical analysis to verify the minimum number of
observations needed to accurately characterize the distribution of the
best-performing 12 percent of units in each subcategory. The results
showed that the data utilized by EPA meets or exceeds the number of
observations necessary to provide an accurate representation of that
data distributed from the best-performing 12 percent of the source
population. The EPA maintains that the emissions information that we
have collected is adequate to determine the MACT floor for the best-
performing sources. The EPA disagrees with the commenters'
recommendation to use other types of data, such as permits, other
regulatory limits, or feed rate controls with the emissions information
to calculate the MACT floor. The other types of data mentioned do not
represent the actual emissions or operation of the unit but are
potential values in their permits or limits. Most units are typically
operating at lower than permitted levels or emission limits.
    Additionally, it would be difficult to incorporate such data into
the EPA's UPL calculation because the UPL calculation is based on
emission test runs of actual data, rather than limits based on permits.
The permit or emission limits would be on a different basis and
potentially skew the MACT floor UPL calculation.
    The EPA has also updated the inventory of sources based on
additional data provided in the comment letters. The inventory now
contains 204 SSI units, 60 FB units and 144 MH units. Given this change
in population, 12 percent of each subcategory are equal to 8 FB units
and 18 MH units. Although we do not have any more emissions information
than at proposal, the change in inventory results in more than 12
percent of MH units with data for PM and Hg. For these pollutants, we
determined the MACT floor based on the best-performing 12 percent of
emissions data, as documented in the memorandum ``Revised MACT Floor
Analysis for the Sewage Sludge Incinerator Source Category'' in the SSI
docket (EPA-HQ-OAR-2009-0559). EPA solicited additional emission test
reports in the NPRM. Although many commenters summarized the results of
their most recent emission tests when comparing their site-specific
emissions to EPA's baseline emissions, none of the commenters actually
provided the emissions test reports. The emission test reports are
necessary for the EPA to review the test methods and procedures to
ensure consistency with other emissions data, and to verify the tests
represent a valid test result that can be used in the MACT floor
analysis. Additionally, the test reports provide information necessary
to correct the emissions measured into the units used for the MACT
floor analysis. Therefore, these additional test result summaries,
without background documentation, could not be used in the MACT floor
UPL calculation.
    Comment: One commenter stated that, to fill the data gap caused by
the lack of actual emissions data from the required number of units in
each subcategory, EPA applied statistical analysis to single test run
results. Several commenters contended that, in order to enhance the
data available for MACT development, EPA counted each test run as a
separate data point.
    Some commenters stated that basing a MACT Analysis on test runs,
instead of tests, is improper. The commenters noted that CAA section
129 states that MACT standards for existing sources must be as
stringent as the ``emissions limitation achieved by the best performing
12 percent of units in, the category.'' The commenters added that,
assuming that EPA equates the term ``emissions limitation'' with the
concept of emission level (as often stated by EPA), this clause means
that EPA must use the emission levels that have been achieved to set
the MACT floors. The commenters contended that, under the MACT program,
it takes a ``minimum'' of three test runs to make up a valid emissions
level test. The commenter stated that a test run is not an accurate
measure of the performance of the unit and should not be used as if it
were. Commenters added that EPA should use the results of the test for
each unit (comprised of at least three test runs) to represent what is
being achieved by a unit.
    Several commenters contended that EPA must go back and reset the
process based on 12% of MH and 12% of FBI sources (not individual
incinerators). The commenters added that it is important that
individual sources, not units, be utilized because the composition of
the sludge varies greatly from source to source and utilizing multiple
units at one source skews the data development process and ultimately
provides the basis for a flawed MACT standard at best.
    Response: We disagree with the commenters. The 99 percent UPL
values were calculated for each pollutant and for each subcategory
using the test run

data for those units in the best-performing 12 percent. Consistent with
EPA's procedures on other MACT standards, such as HMIWI, CISWI, and
boilers, the MACT floor emission limits were calculated on a run basis
since compliance is based on the average of a 3-run test. The 99
percent UPL represents the value which one can expect the mean of
future 3-run performance tests form the best-performing 12 percent of
sources to fall below, with 99 percent confidence, based upon the
results of the independent sample observations from the same best-
performing sources.
Variability Calculation
    For the final rule, as in the NPRM, we are incorporating
variability in the MACT floor calculation for this source category
using the 99 percent UPL. We are also following the same procedures for
establishing limits and incorporating non-detect values as discussed in
the NPRM. We have made three revisions to the variability calculation
for the final rule. First, we revised the MACT floor variability
calculation to incorporate weighted UPL's for existing FB units.
Second, we selected log-normal results when it is not clear that data
are normally distributed. Lastly, we revised the CO limits based on an
analysis of the span of the test. The weighted UPL's and log-normal
results are discussed in responses to comments. The revision to the CO
limits based on reviewing the CO span was done to correct errors in the
CO values provided in test reports and to be consistent with the
calculation methods used in the CISWI and boilers rules.
    Carbon monoxide values obtained from emission test reports were
reviewed to determine whether the span of the test used was capable of
accurately reading the reported value. If the span was inconsistent
with the reported value, the CO levels were adjusted to provide a value
that was more consistent with the span. EPA Method 10 is structured
such that measurement data quality relative to the calibration span of
the instrument can be assessed. For a measurement made using an
instrumental test method, the equivalent of the method detection level
can be assessed using: a square root formula, the reported calibration
span value, and the allowable data quality criteria (i.e. the allowable
calibration error, bias, and drift values). The estimated CO
measurement error resulting from the square root formula was adjusted
by a factor of three to be consistent with the methodology EPA applied
for non-detect data (where limits no less than three times the method
detection level were established).
    In order to develop a basis for measurement error, instrument
calibration spans in available test reports were reviewed. Where no
span values could be found, it was assumed that if the test was
conducted on or before May, 2008, the associated CO span would be 1000
ppm, and tests conducted after May 2008 would have a CO span of 100
ppm. This assumption was made because, before revisions were made to
Method 10 in May of 2008, it was common that units were using the
prescriptive span guidance that was listed in the old method. The
current version of EPA Method 10 does not include these span
requirements but instead requires the tester to choose calibration
ranges that reflect the range of expected emission concentrations at
the unit. In cases where the reported emission concentrations were
lower than their corresponding measurement errors, the default
measurement errors were used in lieu of the reported concentration.
    These revisions are further documented in the memorandum ``Revised
MACT Floor Analysis for the Sewage Sludge Incinerator Source Category''
in the SSI docket (EPA-HQ-OAR-2009-0559). Table 7 of this preamble
shows the revised results of the MACT floor analysis for existing
sources, and Table 8 of this preamble shows the results for new
sources.

                         Table 7--Summary of MACT Floor Analysis for Existing SSI Units
----------------------------------------------------------------------------------------------------------------
                                                                                MACT floor        MACT floor
                                                                               emission limit    emission limit
                  Pollutant                                Units                   for FB            for MH
                                                                               incinerators a    incinerators a
----------------------------------------------------------------------------------------------------------------
Cd..........................................  mg/dscm@7% O2.................            0.0016             0.095
CO..........................................  ppmvd@7% O2...................                64             3,800
HCl.........................................  ppmvd@7% O2...................            b 0.51               1.2
Hg..........................................  mg/dscm@7% O2.................             0.037            b 0.28
NOX.........................................  ppmvd@7% O2...................               150               220
Pb..........................................  mg/dscm@7% O2.................            0.0074              0.30
PCDD/PCDF TEQ...............................  ng/dscm@7% O2.................               0.1              0.32
PCDD/PCDF TMB...............................  ng/dscm@7% O2.................               1.2               5.0
PM..........................................  mg/dscm@7% O2.................                18                80
SO2.........................................  ppmvd@7% O2...................                15                26
----------------------------------------------------------------------------------------------------------------
a Limits were rounded up to two significant figures.
b Limits represent three times the detection level.

                            Table 8--Summary of MACT Floor Analysis for New SSI Units
----------------------------------------------------------------------------------------------------------------
                                                                                MACT floor        MACT floor
                                                                               emission limit    emission limit
                  Pollutant                                Units                   for FB            for MH
                                                                               incinerators a    incinerators a
----------------------------------------------------------------------------------------------------------------
Cd..........................................  mg/dscm@7% O2.................            0.0011            0.0024
CO..........................................  ppmvd@7% O2...................                27                52
HCl.........................................  ppmvd@7% O2...................              0.24             c 1.2
Hg..........................................  mg/dscm@7% O2.................            0.0010            b 0.15
NOX.........................................  ppmvd@7% O2...................                30               210
Pb..........................................  mg/dscm@7% O2.................           0.00062            0.0035
CDD/CDF TEQ.................................  ng/dscm@7% O2.................            0.0044            0.0022
CDD/CDF TMB.................................  ng/dscm@7% O2.................             0.013             0.045

PM..........................................  mg/dscm@7% O2.................               9.6                60