United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
EPA 450/3-92/007(3)
June 1993
Air
©EPA Guidelines for MACT PROPOSAL
Determinations under
Section 112(j)
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ABSTRACT
Section 112(j) of the Clean Air Act as amended in 1990
requires major sources within a source category to apply for a
Title V permit should the Environmental Protection Agency fail to
promulgate emission standards for that source category by the
date specified in the regulatory schedule established through
Section 112(i) of the Act. The Title V permit application must
demonstrate the major source's ability to achieve a maximum
achievable control technology (MACT) emission limitation for all
hazardous air pollutant emissions. Regulations to implement
Section 112(j) will be published in 40 CFR Part 63, Subpart B.
This document provides guidance for complying with these
regulations by identifying and evaluating control technology
options to determine the MACT emission limitation.
U.S. Environmental Protection Agency
Region 5, Libra."..- 'PI-12J)
77 West Jackso.i • " ;.>varrt
Chicago, IL 60604-3590
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Table of Contents
Introduction iv
Chapter 1.0 An overview of the MACT Determination Process.... l
1.1 Overview of Statutory Requirements 1
1.2 Overview of the Regulatory Requirements 4
1.3 Administrative Review Process for
for New Emission Units 7
1.3.1 Application Process 7
1.3.2 Contents of Application 14
Chapter 2.0 The MACT Determination...
a Permitting Agency' s Perspective 16
2.1 Criteria for the MACT Determination 16
2.2 Compliance Provisions 20
2.3 Available Control Technologies 23
2.4 Approaches to the MACT Determination 25
2.5 General Permits 28
Chapter 3.0 The MACT Analysis 30
3.1 Overview of the MACT Analysis Process 31
3.2 A Detailed Look at the MACT Analysis 36
3.3 Determining the MACT-Affected Source on a
Case-by-Case Basis 47
3.4 Similar Emission Units 53
3. 5 Subcategorization 57
Chapter 4 . 0 The MACT Floor Finding 58
4.1 Calculation of the MACT Floor 62
4.2 Method 1- Computing the MACT floor using
existing State and Local Regulations 68
4.3 Method 2 - Computing the MACT Floor using
Control Efficiency Ratings 73
4.4 Method 3 - Computing the MACT Floor using
Emission Reduction Ratios (ERR) 77
4.5 Exceptions to the Emission Reduction
Ratios 83
4.6 Other Methods to Compute
the MACT Floor 84
Chapter 5.0 Costs, Non-Air Quality Health and Environmental
Impacts and Energy Requirements 79
5.1 Costs Impacts 81
5.2 Environmental Impacts 84
5.3 Energy Requirements 86
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,88
Chapter 6.0 Information Sources
References
Appendix A Examples of MACT Analyses A-l
Appendix B Forum of Anticipated Questions B-l
Appendix C Definitions c~1
Appendix D List of Major Source Categories D-l
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LIST OF FIGURES
Figure 1 Example Notice of MACT Approval 10
Figure 2 Three Tiers to the MACT Analysis 32
Figure 3 Acceptable Methods for Determining
the MACT Floor 62
Figure 4 Using State or Local Air Pollution Regulations to
compute the MACT Floor 69
Figure 5 Analysis of State Regulations
for Emission Unit X 71
Figure 6 Using Control Efficiency Ratings
to Compute teh MACT Floor 74
Figure 7 Using Emission Reduction Ratios
to Compute the MACT Floor 78
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Introduction
This guidance document is designed to clarify the statutory
and regulatory requirements for MACT determinations as required
by Section 112(j) of the Clean Air Act (the Act) as amended in
1990. It sets forth procedures for determining emission
limitations based on maximum achievable control technology for
major sources who are required to apply for a new Title V permit,
revise an existing permit, or apply for a Notice of MACT approval
because the promulgation deadline for a MACT standard was missed
by greater than 18 months for an applicable source category.
The manual is divided into five chapters and a four section
appendix. Chapter 1 of this manual provides an overview of the
statutory and regulatory requirements and discusses the
procedures for applying for a Notice of MACT approval. Chapter 2
outlines the criteria a permitting agency should use when
evaluating applications as well as possible approaches permitting
agencies may use for determining the appropriate level of control
for each source. Chapter 3 describes the process for selecting a
control technology that meets the criteria discussed in Chapter
2. Chapter 4 describes the analysis that may be required to
assess the costs of achieving the emission reduction, and any
non-air quality health and environmental impacts and energy
requirements associated with use of different control options.
Chapter 5 discusses the national databases that may assist in the
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collection of available information.
Part A of the Appendix illustrates examples for defining a
MACT-affected emission unit, and selecting a control technology
to meet MACT. Part B is a question and answer forum. It is
designed to deal with detailed questions on applicability and
other issues. Part C of the Appendix contains a glossary of
terms and definitions. In Appendix D, a complete list of source
categories of major sources is provided. This listing is current
only to the date of this publication. Readers are referred to
the Federal Register for any changes to this listing.
It is hoped that this guidance document contains useful
information for implementation of MACT determinations. For more
information on MACT determinations, the reader is advised to read
40 CFR Part 63, Subpart B, and Section 112 of the Act.
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Chapter 1.0
An Overview of the
MACT Determination Process
for Section 112(j)
1.1 Overview of Statutory Requirements
Beginning after the effective date of an approved permit
program, (but no sooner than May 15, 1994,) Section 112(j) of the
Clean Air Act as amended in 1990 (The Act), requires an owner or
operator of a major source to submit either a new Title V permit
application or a revision to an existing permit if such major
source is part of a source category for which the promulgation
deadline for a relevant Section 112(d) or 112(h) standard has
been missed by 18 months. The promulgation deadline for each
source category will be established through the regulatory
schedule in accordance with Section 112(e) of the Act. A
proposed regulatory schedule was published on September 24, 1992
in the Federal Register.
Section 112 (j) also requires States or local agencies with
approved permit programs to issue permits or revise existing
permits for all of these major sources. These permits must
contain either an equivalent emission limitation or an alternate
emission limitation for the control of hazardous air pollutants
(HAPs) from the major source. An equivalent emission limitation,
also referred to as a MACT emission limitation, will be
determined on a case-by-case by the permitting agency for each
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source category that becomes subject to the provisions of Section
112(j). The MACT emission limitation will be "equivalent" to the
emission limitation which the source category would have been
subject to if a relevant standard had been promulgated under
Section 112(d) (or Section 112(h)).
In accordance with Section 112(d), the MACT emission
limitation will require a maximum degree of reduction of
hazardous air pollutant emissions (HAPs) taking into
consideration the costs of achieving such emission reductions,
and any non-air quality health and environmental impacts and
energy requirements. For new sources, the MACT emission
limitation will be no less stringent than the emission control
that is achieved in practice by the best controlled similar
source. For existing sources the MACT emission limitation will
be no less stringent than:
the average emission limitation achieved by the best
performing 12 percent of the existing sources (for which the
Administrator has emissions information), excluding those
sources that have, within 18 months before the emission
standard is proposed or within 30 months before such
standard is promulgated, whichever is later, first achieved
a level of emission rate or emission reduction which
complies, or would comply if the source is not subject to
such standard, with the lowest achievable emission rate (as
defined by Section 171 (of the Act)) applicable to the
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source category and prevailing at the time, in the category
or subcategory for categories and subcategories with 30 or
more sources; or,
the average emission limitation achieved by the best
performing 5 sources (for which the Administrator has or
could reasonably obtain emissions information) in the
category or subcategory for categories or subcategories with
fewer than 30 sources.
These minimum requirements for the MACT emission limitation for
new and existing sources are termed the "maximum achievable
control technology (MACT) floor".
An alternate emission limitation is a voluntary emission
limitation that an owner or operator of a major source has agreed
to achieve through the early reductions program. (See 57 FR
61970.) The alternate emission limitation can be written into
the permit in lieu of an equivalent emission limitation only if
the source has achieved the required reduction in HAP emissions
before the missed promulgation deadline for the relevant Section
112(d) (or 112(h)) standard.
Section 112 (j) also requires EPA to establish requirements
for owners or operators and reviewing agencies to carry out the
intent of Section 112(j). These requirements are contained in
Chapter 40, Part 63, Subpart B of the Code of Federal
Regulations.
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1.2 Overview of the Regulatory Requirements
The owner or operator or a major source is required to apply
for a Title V permit, when the promulgation deadline for a
relevant Section 112(d) as been missed. The permit application
must be received by the permitting agency no later than 18 months
from the date that the promulgation deadline was missed. EPA
also recommends that an owner or operator of a major source
subject to the provisions of Section 112(j) also be required to
obtain a Notice of MACT Approval before constructing a new
source, or reconstructing an existing source. This
recommendation is discussed in greater detail in Section 1.3 of
this chapter.
In preparing an application for a Title V permit or a Notice
of MACT Approval, the owner must recommend a level of control and
appropriate monitoring, reporting and recordkeeping parameters
for control of HAP emissions from each existing source or new
source within the source category. The recommended level of HAP
emission control should be based on the maximum achievable
control technology (MACT), and be no less stringent than the MACT
floor (when information is available to determine the MACT floor
level of control.)
Chapter 3 of this manual discusses a process for developing
the information required in the Title V permit application or
application for a Notice of MACT Approval. The process is termed
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the "MACT analysis". This analysis includes a MACT floor
finding, establishing a MACT emission limitation and selecting a
control technology to meet this emission limitation.
Ideally, State and local agencies will coordinate efforts
with other agencies, and with owners or operators of affected
major sources to develop a source category equivalent emission
limitation before the deadline for permit application submittal.
If a State or local agency can provide an owner or operator with
all available information, or if the State conducts the MACT
analysis, it would not be necessary for an owner or operator to
conduct an independent MACT analysis to complete the required
application. The information made available from the State or
local agency can be used to complete the application. However,
failure of any given permitting agency to make information
available to an owner or operator or conduct the MACT analysis in
advance to the application submittal does not relieve the source
of its statutory obligation to submit a permit application; or,
if a permitting agency requires it, the obligation to apply for a
Notice of MACT approval. Coordination of State efforts is
discussed in greater detail in Chapter 2 of this manual.
Once the MACT analysis is complete the owner or operator can
prepare the Title V permit application or application for a
Notice of MACT Approval. The application for a Title V permit
should be prepared in accordance with the provisions contained in
40 CFR Part 63 and 40 CFR part 70 or CFR Part 71 whichever is
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applicable to the major source.
The requirements for new sources are also codified in 40 CFR
Part 63, Subpart B. Section 1.3 of this chapter describes a
recommended process for determining that a new source will meet a
new source level of emission control.
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1.3 Administrative Review Process for New Sources
1.3.1 Application Process
Subpart B of 40 CFR Part 63 recommends that the permitting
agency require any owner or operator of a major source that is
subject to Section 112(j) of the Act undergo a preconstruction
review if the major source constructs a new source or
reconstructs an existing source and intends to commence
construction of this source after 18 months from the missed
promulgation deadline. This preconstruction review process would
be automatically required if the new source also meets the
definition of a constructed, reconstructed or modified major
source established under the regulatory provisions for Section
112(g) of the Act, (also contained in 40 CFR Part 63, Subpart B.)
Some owners or operators may also be required to obtain a Part 70
or Part 71 revision if a source's existing Title V permit
prohibits the construction of a new source or reconstruction of
the existing source without first obtaining a permit revision.
When a revision to a permit is not specifically required in
advance of the major source change, and an owner or operator does
not voluntarily revise or obtain the Title V permit before
construction, EPA recommends that the permitting agency require
that the owner or operator obtain a Notice of MACT approval
before commencing construction of the proposed source.
The Notice of MACT approval can serve as the mechanism to
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ensure federal enforceability of the requirements established
during the preconstruction review before such requirements are
incorporated into the Title V permit. As required by Part 70,
the requirements contained in the Notice of MACT approval would
be incorporated into the permit within 12 months from the start-
up of the source. This would be done through either a
significant permit revision or an administrative amendment to the
permit.
After receiving an application for a MACT determination, the
EPA recommends that the permitting agency have 30 calendar days
to review the application for completeness. No later than 30
calendar days from the date that an application is received, the
reviewing agency should notify the owner or operator in writing
that the application is complete or that additional information
is required. If the reviewing agency fails to issue a status of
completeness notice within the 30 day period, the application
could automatically be deemed complete. After a notice of
completion is issued, the reviewing agency should have 60
calendar days to issue a preliminary Notice of MACT Approval or
disapprove the application. The 60-day period could begin on the
date that the notice of completion is issued.
Before issuing a final disapproval of an application, the
reviewing agency should inform the applicant in writing of the
intent and grounds for the disapproval. The applicant should
have 30 days from the date of notification to supply additional
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information, or amendments to the application. If no additional
information is received in 30 days, a final disapproval should be
issued. If additional information is submitted, the reviewing
agency should have 30 additional days to review the information
and issue a preliminary Notice of MACT approval or issue a final
disapproval of the application. A final disapproval should be in
writing and should specify the grounds on which the disapproval
was based.
In order for the requirements in a Notice of MACT Approval
to be federally enforceable, EPA and the public must be provided
the opportunity to review the notice before final issuance. EPA
recommends that the Notice of MACT Approval undergo a 45 day
review period, during which the EPA or the public may comment on
the preliminary notice. The final Notice of MACT approval could
then be issued after this public review period. Figure 1
provides a suggested format for the Notice of MACT Approval.
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Figure 1
Example Notice of MACT Approval
Notice of MACT Approval
CFR 40, Part 63, Subpart B
Maximum Achievable Control Technology Emission Limitation
for
Constructed, Reconstructed or Modified Source
This notice establishes federally enforceable maximum
achievable control technology emission limitation(s) and
requirements for Name of manor source for the MACT-affected
emission unit(s) located at location all MACT-affected emission
units. The emission limitations and requirements set forth in
this document are federally enforceable on effective date of
notice.
A. Major source information
1. Mailing address of owner or operator:
2. Mailing address for location of manor source;
3. Source category for manor source:
4. MACT-affected emission unit(s): List all emission
unit(s) subject to this Notice of MACT Approval along
with the source identification number if applicable.
5. Type of modification, construction or reconstruction:
Describe the action taken by the owner or operator of
the major source that triggered the requirements of 40
CFR Part 63, Subpart B.
6. Anticipated commencement date for construction.
reconstruction or modification:
7. Anticipated start-up date of constructed, reconstructed
or modified emission unit(s):
8. List of the hazardous air pollutants potentially
emitted bv MACT-affected emission unit(s): List all
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hazardous air pollutants that are or could possibly be
emitted from the affected emission unit(s). Any
pollutant not listed in this section can not be emitted
by the emission unit without an amendment to the Notice
of MACT Approval.
B. MACT Emission limitation
1. The above stated owner or operator shall not exceed the
following emission limitation(s) for the above stated
MACT-affected emission unit(s). Write in emission
standard or MACT emission limitation for overall
hazardous air pollutant emissions from each affected
emission unit. If the permitting authority determines
that an individual pollutant emission limitation is
appropriate, it should also be listed in this section.
2. The above stated owner or operator shall install and
operate the following control technology(s), specific
design equipment, work practice, operational standard,
or combination thereof to meet the emission standard or
MACT emission limitation listed in paragraph 1 of this
section. List all control technologies to be installed
by the owner or operator and which emission units the
control technologies will reduce HAP emissions from.
3. The above stated owner or operator shall adhere to the
following production or operational parameters for the
technologies listed in paragraph 2 of this section.
State all production or operational parameters. For
example:
The owner or operator may, subject to [name of
agency] approval, by pass the emission control
device for a limited period of time for purposes
such as maintenance of the control device.
The owner or operator shall operate and maintain
the control equipment such that it has a 95%
hazardous air pollutant destruction efficiency.
The owner or operator shall not operate the MACT-
affected emission unit for greater than 6 hours in
any 24 hour period of time.
C. Monitoring requirements
For each MACT emission limitation and operational
requirement established in Section B (MACT emission
limitation) the above stated owner or operator shall comply
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with the following monitoring requirements. State all
monitoring requirements. For example:
After installing the control equipment required to
comply with Section(B)(1) visually inspect the internal
floating roof, the primary seal, and the secondary
seal, before filling the storage vessel
The owner or operator shall calibrate, maintain and
operate a continuous monitoring system for the
measurement of opacity of emissions discharged from the
control device required in Section(B)(2) according to
the following procedures:
D. Reporting and Recordkeeping Requirements
List all reporting and recordkeeping requirements in this
section. For example:
The owner or operator shall maintain at the source for
a period of at least 5 years records of the visual
inspections, maintenance and repairs performed on each
secondary hood system as required in Section(B)(2).
E. Other requirements
1. The above stated owner or operator shall comply with
all applicable requirements specified in the general
provisions set forth in Subpart A of 40 CFR Part 63,
including but not limited to notification operation and
maintenance, performance testing, monitoring,
reporting, and recordkeeping requirements. If there are
any specific requirements that the reviewing agency
would like to clarify, those requirements should also
be stated in this paragraph. This paragraph could also
include requirements for emergency provisions and
start-up and shut-down procedures.
2. In addition to the requirements stated in paragraph 1
of this section, the owner or operator will be subject
to these additional requirements. Any additional
requirements not specified in Subpart A of 40 CFR Part
63 should be stated in this paragraph. If the
reviewing agency wishes to require a mandatory retest
of a failed performance test that should be stated in
this paragraph, along with any other requirements
specified by the reviewing agency.
F. Compliance Certifications
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The above stated owner or operator shall certify compliance
with the terms and conditions of this notice according to
the following procedures: This sections should include a
description of the terms and condition that the owner or
operator will use to certify compliance, as well as, the
format and frequency of the certification.
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1.3.2 Contents of Application:
After the owner or operator has determined a MACT emission
limitation and selected the MACT, the owner or operator should
prepare an application for a Title V permit or Notice of MACT
Approval. There is no standard Federal form for the application;
however, individual States may develop there own application
forms.
All applications for a MACT determination should contain the
following information:
(a) The applicant's name and address;
(b) A brief description of the major source, its source
category or subcategory, and a description of the
affected emission units;
(b) A notification of intention and date to construct,
reconstruct, or modify;
(c) The address (physical location) of the affected
emission unit;
(d) The expected commencement date of construction,
reconstruction, or modification;
(e) The expected completion date of construction,
reconstruction, or modification;
(f) The anticipated date of start-up;
(g) A list of HAPs emitted by the emission unit and rate of
emission;
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(h) The uncontrolled emissions for the emission unit;
(i) A description of the MACT including technical
information on the design, operation, size, estimated
control efficiency, etc.;
(j) Supporting documentation such as a the costs, non air
quality health and environmental impacts and energy
requirements analysis;
(k) Controlled emissions for the emission unit;
(1) Any federally enforceable limits already imposed on the
affected emission unit;
(n) Other information which may be required pursuant
to 40 CFR Part 63, Subpart A
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Chapter 2.0
The MACT Determination...
a Permitting Agency's Perspective
2.1 Criteria for the MACT Determination
The process of reviewing the Title V permit application or
the application for a Notice of MACT Approval to determine an
equivalent (MACT) emission limitation is called a MACT
determination. For MACT determinations under Section 112(j), the
MACT emission limitation should be comparable to the emission
limitation(s) or requirements that would likely be imposed if a
Section 112(d) or Section 112(h) emission standard had been
promulgated for that source category. The Clean Air Act sets
forth specific criteria for setting a hazardous air pollutant
emission standard under Sections 112(d) and Section 112(h).
These criteria should also be used when establishing the MACT
emission limitation under Section 112(j).
In conducting the MACT determination, the permitting agency
must determine if the owner or operator has recommended an
appropriate MACT emission limitation(s) or other requirements for
the MACT-affected emission unit, given the expected performance
of the maximum achievable control technology (MACT). When
conducting a MACT determination, the permitting agency should
evaluate the application to determine if the recommended MACT
emission limitation, and the suggested control technology meet
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the following criteria:
(a) When a relevant emission standard has been proposed
pursuant to Section 112(d) or 112(h) of the Act, the
MACT emission limitation and control technology
selected by the owner or operator achieves all emission
limitations and requirements of the proposed standard.
(b) When a relevant emission standard has not be
promulgated or proposed pursuant to Section 112(d) or
Section 112(h):
(1) The owner or operator documents a MACT floor
finding based on all available information, and
(2) When a positive MACT floor finding is made, the
application recommends a MACT emission limitation
and selects a control technology that is at least
equal to the MACT floor and achieves the maximum
degree of emission reduction of the hazardous air
pollutants with consideration to the costs,, non-
air quality health and environmental impacts and
energy requirements associated with the emission
reduction; or,
(3) When a negative MACT floor finding is made, the
owner or operator recommends a MACT emission
limitation and control technology to meet this
limitation with consideration to costs, non-air
quality health and environmental impacts, and
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energy requirements after evaluating all control
technologies that can be identified through
available information and that have been
successfully demonstrate in practice for a similar
source; and,
(4) When a MACT emission limitation can not be
prescribes due to the nature of the process or
pollutant, the owner or operator designates a
specific design, equipment, work practice,
operational standard, or a combination thereof,
that achieves a maximum degree of emission
reduction.
The MACT floor finding is a determination of whether a level of
HAP emission control that is equal to the MACT floor can be
determined using available information. The MACT floor finding
is discussed further in Section 3.6 of Chapter 3. The definition
of available information is discussed in Section 2.3 of this
Chapter.
The MACT emission limitation could be expressed as a
numerical emission limitation on the total quantity of HAP
emissions from the source in tons per year (tpy); or, it could
be expressed as unit per production ratio. The MACT emission
limitation could also be a performance standard based on the
expected efficiency of MACT in reducing HAP emissions. If it is
infeasible to prescribe a specific numerical limitation or
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reduction efficiency the MACT emission limitation can also be
expressed based on a design, equipment, work practice,
operational standard, or any combination of these.
If an individual hazardous air pollutant is of particular
concern, a MACT limitation should also be placed on that
pollutant based on the expected level of reduction with MACT in
place. Reviewing agencies have discretionary authority to impose
an individual MACT emission limitation on a specific hazardous
air pollutant. In addition to recommending the MACT emission
limitation, the reviewing agency should specify any requirements
that are necessary in order to make the emission limitation
federally enforceable as a legal and practical matter. This
involves establishing appropriate operational or production
limits and monitoring parameters to ensure compliance with the
MACT emission limitation. The following section discusses
compliance provisions in greater detail.
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2.2 Compliance Provisions
Each Title V permit and Notice of MACT approval must contain
sufficient testing, monitoring, reporting, and recordkeeping
requirements to ensure that the MACT emission limitation is
federally enforceable as a legal and practical matter.
In order to be federally enforceable, operational limits or
production limits must be imposed on the source in addition to a
blanket emission limitation. For example, a blanket 40 tpy MACT
emission limitation on HAPs would not be federally enforceable.
In addition to the blanket emission limitation, a source may be
required to comply with a production limitation that limits the
amount of gallons used per hour in the operation; or the source
may be required to comply with an operational limitation on its
hours of operation and emission rate, that when multiplied
together can result in emissions from the source that do not
exceed 40 tpy.
Production limits are restrictions on the amount of final
product which can be manufacture or otherwise produced at the
source. Operation limitations are other restrictions on the
manner in which a source is run. Operation limitations include
limits on quantities of raw material consumed, fuel combusted,
hours of operation, or conditions which specify that the source
must install and maintain controls that reduce emissions to a
specified emission rate or level.
When the permit or Notice of MACT Approval requires an add-
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on control, operating parameters and assumptions that can be used
to determine the efficiency or emission rate of the devise should
be specified in the document. For example, a source may have a
MACT emission limitation that requires a control devise to be
installed and operated at a 95% efficiency rate. An operational
limit on the range of temperatures that the devise can be
operated under could be sufficient to ensure federal
enforceability, if operating the control devise within this
temperature range ensures that the devise achieves a 95%
destruction efficiency.
If establishing operating parameters for control equipment
is infeasible in a particular situation, a short term emission
limit (e.g. Ibs/hr) would be sufficient provided that such limits
reflect the operation of the control equipment, and additional
requirements are imposed to install, maintain, and operate a
continuous emission monitoring system (GEM). A Title V permit or
Notice of MACT Approval should also specify that CEM data may be
used to determine compliance with the MACT emission limitation.
If parameter monitoring of a production or operational limit
is infeasible due to the wide variety of coatings or products
used or the unpredictable nature of the operation, emission
limits coupled with a requirement to calculate daily emissions
may be required. For instance, a source could be required to
keep the records of the daily emission calculation, including
daily quantities and the HAP content of each coating used.
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For either operation or production limitations to be
enforceable as a practical matter, the limitations should extend
over the shortest practicable time period, generally not to
exceed one month. If it is not practicable to place a monthly
limit on the source, a longer time can be used with a rolling
average period. However, the limit should not exceed an annual
limit rolled on a monthly basis.
In addition to conveying practical enforceability of a MACT
emission limitation, the Title V permit or Notice of MACT
Approval should require testing or instrumental or
noninstrumental monitoring that yields data this is
representative of the source's operations and can be used to
certify the source's compliance with the terms and conditions of
the Title V permit or Notice of MACT Approval. Such testing or
monitoring requirements may be in the form of continuous emission
monitoring systems, continuous opacity monitoring systems,
periodic testing, or it may consist of recordkeeping designed to
serve as monitoring. If periodic testing is required, the
specific EPA approved method or equivalent method that is to be
used should be specified in the permit or notice.
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2.3 Available Control Technologies
Section 112(j) states that permits issued pursuant to
Section 112(j) shall contain an equivalent emission limitation.
This emission limitation is to be "equivalent" to that which the
source would have been subject to if an applicable Section 112(d)
or Section 112(h) emission standard had been promulgated. In
order to establish an emission limitation that would be
equivalent, the permitting agency must determine the equivalent
emission limitation with consideration to the MACT floor using
available or reasonably available emissions information.
For the purposes of a Section 112(j) MACT determination,
emission information is considered available or reasonably
obtainable to the permitting agency if the information can be
obtained from EPA's Office of Air Quality, Planning and
Standards, the EPA's National MACT database or other publically
available databases (See Chapter 5), from State or local agencies
or within the permitting agency itself. A permitting authority
is not required to obtain additional information from databases
or other State and local agencies if the information used to
propose a Section 112(d) or Section 112(h) standard is used to
establish the MACT floor.
It is not necessary for the MACT floor to be determined
based on emissions information from every existing source in the
source category if such information is not available. Once a
permitting agency has obtained available information, the MACT
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floor can be determine using this information if it is
representative of the source category.
EPA realizes that the information that is reasonably
available or obtainable for the permitting agency is not
necessarily reasonably available to the owner or operator.
Owner's or operator should submit an application for Title V
permit or a Notice of MACT Approval based on information that the
owner or operator is able to obtain. The permitting agency
should use the completeness of application review period to
determine if the owner or operator should consider additional
information that is reasonably available to the permitting
authority. An amended application should be submitted if
additional information should be consider in the MACT analysis.
Once the application is deemed complete, additional information
that comes available does not need to be considered before
issuing the Title V permit, or Notice of MACT Approval if the
information was not reasonably available at the time of the
completeness determination.
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2.4 Approaches to the MACT determination
Section 112(j) states that permits issued pursuant to
Section 112(j) shall contain an equivalent emission limitation.
This equivalent emission limitation is to be determined on a
case-by-case basis. The EPA views the case-by-case determination
required under Section 112(j) and that required under Section
112(g) (modification, construction and reconstruction provisions)
to be fundamentally different. While Section 112(g) would
require a case-by-case determination for each source, EPA views
the determination under Section 112(j) to be a case-by-case
determination for each source category, or a "source category-by-
source category" determination. EPA would like to see a
consistent approach in defining the boundaries of the existing
source and new source, and defining the level of control required
for all sources in the source category.
Several different approaches to the MACT determination
process could be taken by a permitting agency. An agency could
wait until all applications for permits are received to determine
the equivalent emission limitations that would apply to all the
sources. Or, an agency or a group of agencies could conduct a
"MACT analysis" based on available information before the
deadline for application submittal.
The first approach requires less upfront coordination on the
part of the permitting agency. While a permitting agency is not
legally bound to conduct an information search before reviewing
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the permit applications, the permitting authority will need to
assure that all available information has been considered in
evaluating the application. If a permitting agency chooses to
wait until an application is received to determine the extent of
information that is available, several permit applications may
need to be revised to reflect information identified by the
agency. Also, under this approach each application will need to
undergo public review. The implications of this are that there
may be less consistency in the source category by source category
equivalent emission limitation for each major source. While this
may be unavoidable when each permit is reviewed on an individual
basis, a permitting agency may need to justify any discrepancies
between the level of control required for existing sources within
the same source category.
The second approach would allow a permitting agency to
convey information to an applicant in advance of the application
submittal. A permitting agency could conduct an information
search to determine the available information, or a "coalition"
of permitting agencies could be formed to facilitate the
information exchange. Once the available information is
identified the permitting agency could conduct a MACT analysis
(See Chapter 3) to determine the appropriate level of control for
each source. The control level could be established through a
State regulation or general permit. The following section of
this chapter discusses the concept of general permits in greater
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detail.
If a permitting agency is unable to establish the level of
control through a State regulation or general permit, the
available information could be used for information exchange with
each permit applicant. This would assure greater consistency in
control levels recommended by the applicants.
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2.4 General Permits
A general permit is a type of Title V permit. A single
general permit could be issued by a permitting authority to cover
a number of sources. The specific requirements for a general
permit are contained in 40 CFR Part 70.6(d).
The general permit can be written to set forth requirements
for an entire source category, or portion of the source category.
The facilities that are covered by the general permit, should be
homogenous in terms of operations, processes, and emissions. In
addition, the facilities should have essentially similar
operations or processes and emit pollutants with similar
characteristics. The facility should be subject to the same or
substantially similar requirements governing operations,
emissions monitoring, reporting, or recordkeeping.
Because the case-by-case determination under Section 112(j)
is a source category-by-source category determination of an
equivalent emission limitation, the permitting agency could use
the general permit as a mechanism to issue Title V permits to the
entire source category, or specific emission units within the
source category. By using this mechanism, a permitting agency
would not be required to issue individual permits to sources
covered by the general permit. Also, once the general permit has
been issued and after opportunity for public participation, EPA
review and affected State review, the permitting authority may
grant or deny a source's request to be covered by a general
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permit without further outside review.
Major sources that do not require a specific Title V permit
for any other reason, could be covered by the general permit
indefinitely. For a major source that already has a Title V
permit, the owner or operator can apply for coverage under the
general permit, and then incorporate the general permit
requirements into the source specific permit through an
administrative amendment at permit renewal.
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Chapter 3
The MACT Analysis
For most source categories, the process of recommending a
level of control involves a number of decisions either on the
part of the owner or operator preparing an application for a
Title V permit or Notice of MACT Approval, or a permitting agency
who is conducting a MACT determination. First, the source
category boundaries must be defined. All points within this
boundary that emit one or more hazardous air pollutants are
subject to control through an eguivalent emission limitation and
must be addressed in the permit application(s). Within this
source category boundary there may be one or more existing
sources (stationary sources) for which an equivalent emission
limitation will be established. The existing source boundary may
be synonymous with the source category boundary, or a single
source category may contain several existing sources.
For each existing source, the MACT floor level of control
must be determined. The application submitted by an owner or
operator must recommend an equivalent MACT emission limitation
that is no less stringent than the MACT floor, but could be more
stringent if a greater degree of HAP emission reductions can be
achieved with consideration to the costs, non-air quality health
and environmental impacts and energy requirements associated with
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achieving the additional emission reductions.
The process by which these decisions are made have been
termed the MACT analysis. The following sections of this Chapter
describe a MACT analysis process that EPA has developed to meet
the requirements of 40 CFR Part 63, Subpart B as described in
Section 2.1 of Chapter 2.
3.1 Overview of the MACT Analysis Process
Along with determining the existing or new source
boundaries, the MACT analysis uses available information to make
a MACT floor finding. There are several possible situations that
may arise in the course of conducting a MACT analysis. First,
the MACT floor could be determined, and control technologies that
meet the MACT floor requirement could be identified. This is
known as a positive MACT floor finding. Another possible outcome
is that the MACT floor equals "no control". The third possible
outcome is that the MACT floor can not be determined. This could
be due to the nature of the pollutants emitted from the source,
the lack of available data, or because there are less than five
sources in the source category. In these cases, a negative MACT
floor finding is made.
Because of the variety of situations that could arise, the
MACT analysis has been divided into three tiers. Figure 2
diagrams the steps for Tier I, Tier II and Tier III of the
analysis. If a positive MACT floor finding is made, the owner or
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Figure 2 The MACT Analysis
Tier I -- Making a
MACT Floor Finding
1) Identify the MACT-affected
emission unit.
2) Make a MACT floor finding:
f
i if '
"i positive '
if
negative J
4) Identify MACT
I
Tier II - Considering
All Control Technologies
1)- List all available
control technologies.
2) Eliminate technically
infeasible control options.
3) Conduct a costs, non-air quality
health and environmental impacts,
and energy requirements analysis.
4) Identify MACT
I
Tier
-- Establishing a MACT Emission Limitation
1) Establish the MACT emission limitation (MEL).
2) Select a control technology to meet MEL.
3) Establish monitoring, reporting and recordkeeping parameters.
4) Submit application. .
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operator or a permitting agency is only required to complete Tier
I and Tier III of the MACT analysis. This analysis allows the
owner or operator or a permitting agency to compare the costs,
non-air quality health and environmental impacts and energy
requirements associated with using control technologies that
obtain a level of HAP emission reductions that is equal to or
greater than the MACT floor. If the MACT floor can not be
determined or is equal to "no control" (a negative MACT floor
finding), the owner or operator is also required to complete Tier
II of the analysis.
All MACT analyses should begin with Tier I. During this
Tier, the owner or operator or the permitting agency will
identify the emission points subject to a MACT determination,
(the MACT-affected emission unit,) determine the existing
emission unit or new emission unit boundaries, and make a MACT
floor finding for each emission unit (the MACT-affected emission
unit.) The owner or operator or the permitting agency can make a
MACT floor finding by using available emissions information to
determine if: (1) a specific MACT floor level of control can be
calculated; (2) the very best control technology can be
identified; or, (3) there is a previous case-by-case MACT
determination for a source within that source category. The
procedures detailed Chapter 4 explain several acceptable methods
for determining a MACT floor level of control.
If a negative MACT floor finding is made the owner or
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operator would move to Tier II of the MACT analysis. The purpose
of Tier II is to identify all control technologies using
available information, including work practices, and pollution
prevention methods that could reasonably be applied to the
emission unit subject to the MACT determination. Available
control technologies include but are not limited to: reducing the
volume of, or eliminating emissions of pollutants through process
changes, substitution of materials or other techniques; enclosing
systems or processes to eliminate emissions; collecting,
capturing, or treating pollutants when released from a process,
stack, storage or fugitive emission point; using designs,
equipment, work practices, or operational standards (including
requirements for operator training or certification); or, a
combination of any of these methods. Strategies for identifying
available control technologies are discussed later in this
chapter.
Once a list of available control technologies has been
developed, each control technology should be evaluated to
consider the costs, non-air quality health and environment
impacts, and energy requirements associated with using each
control technology. The control technology(s) achieving the
maximum degree of HAP emission reductions taking into
consideration the costs of achieving such emission reductions and
the non-air quality health and environmental impacts and energy
requirements should be selected as MACT. Once MACT has been
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selected through either Tier I or Tier II of the analysis, the
owner or operator should move to Tier III.
In Tier III, a MACT emission limitation(s) should be
established based on the degree of emission reductions that can
be achieved through the application of the maximum achievable
control technology (MACT); or, a design, equipment, work practice
or operational standard, or combination there of, should be
designated if it is infeasible in the judgement of the permitting
agency to prescribe or enforce a specific MACT emission
limitation based on MACT. The owner or operator or the
permitting agency should also suggest conditions and appropriate
monitoring parameters to make this emission limitation federally
enforceable.
Once the owner or operator has made a MACT floor finding,
established a MACT emission limitation, and selected a control
technology to meet this limitation, the owner and operator should
apply for a Title V permit, or Notice of MACT Approval in
accordance with the procedures contained in 40 CFR Part 63,
Subpart B and 40 CFR Part 70.
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3.2 A Detailed Look at the MACT Analysis
Tier I - Making a MACT floor finding
Step 1 ~ Identify the MACT-affected emission unit(s)
In accordance with the provisions established in 40 CFR Part
63, Subpart B, the owner or operator is required to identify all
emission points emitting one or more HAPs within the source
category boundary. These "affected emission points" will be
grouped into emission units (MACT-affected emission units). Each
of these emission units will be subject to a MACT determination.
When a relevant emission standard has been proposed, the
application should reflect boundaries for the MACT-affected
emission unit that are consistent with the existing source
boundaries, affected emission points, or other portion of the
major source identified by the proposed emission standard. When
no relevant emission standard has been proposed, the MACT-
affected emission unit will be determined on a case-by-case
basis. Section 3.3 of this chapter discusses principles for
determining the MACT-affected emission unit on a case-by-case
basis.
Step 2 — Make a MACT floor finding
The owner or operator will need to determine if there is
enough information available about other emission units to
calculate a level of HAP emission control that is equal to the
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MACT floor for each type of emission unit undergoing review. For
new or reconstructed sources, the MACT floor (or best controlled
similar source) should be determined using emissions information
on similar emission units from within and outside of the source
category. (Section 3.4 clarifies the term similar emission
unit.) For existing emission units, the MACT floor should be
calculated using only emissions information on other emission
units within the source category.
An owner or operator can avoid calculating a specific
emission control level that is egual to the MACT floor, while
still making a positive MACT floor finding by selecting the very
best control technology. The owner of operator is referred to
existing EPA control technology guideline documents (CTG) and
background information documents (BID). These document may help
identify best control strategies for the control of HAPs from a
given type of emission unit. An owner or operator could also
develop a list of available control technologies (similar to that
which would be developed under a Tier II analysis) and establish
a MACT emission limitation based on the control technology that
achieves a maximum reduction in hazardous air pollutant emissions
with consideration to the costs of achieving the emission
reductions, and the non-air quality health and environmental
impacts, and energy requirements. However, minimal consideration
should be given to cost in such an analysis. If an owner or
operator chooses not to, or is unable to identify a MACT floor
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level of control by using any of these methods, the owner or
operator will be required to review all available emissions
information to determine if a specific MACT floor level of
control can be found. The easiest method for determining a
specific MACT floor level of control is to rely on a previous
MACT determination that was made for a similar emission unit
within the source category. A previous MACT determination could
have been made for a similar emission unit due to a construction,
reconstruction or modification according to the provisions of
Section 112(g). The owner or operator is referred to any
existing Federal, State or local data bases as well as the public
record to determine if a MACT determination for a similar
emission unit has recently been made. This MACT determination
can be used to establish the MACT floor, a MACT emission
limitation, and select a control technology as long as there is
no reason to believe that the MACT floor may have changed since
the effective date of that determination. Reasons to believe
that the MACT floor may have changed would include, but are not
limited to, the passing of a State regulation in a particular
State that specifically regulates that type of emission unit.
And, the close down or start up of a number of major sources
within the source category.
If no previous MACT determination has been made, or the
owner or operator would like to calculate a more current MACT
floor, the owner and operator can use emissions information that
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is available for other emission units within the source category.
The degree of emission reductions can be calculated by referring
to existing State and local regulations, or by computing a
control efficiency rating or emission reductions ratio. All of
these methods are detailed in Chapter 4.
If the MACT floor can not be determined or it is equal to
"no control", a negative MACT finding has been made. Under these
circumstances the owner or operator should discontinue Tier I of
the analysis and begin with Tier II as later outlined in this
section of this chapter.
Step 4 — Identifying MACT
When a positive MACT floor finding is made, the owner or
operator will need to identify control technologies that reduce
HAP emissions from the MACT-affected emission unit to the maximum
extent and to a level that is at least equal to the MACT floor.
The control technology that achieves the maximum degree of HAP
emission reductions with consideration to costs, non-air quality
health and environmental impacts, and energy requirements is
MACT. A permitting agency has discretion to determine the weight
that will be given to each one of these factors in identifying
MACT. In doing so, a control technology that exceeds the degree
of emission reductions that is equal to the MACT floor may be
identified as MACT. Under no circumstances should MACT be less
stringent than the MACT floor.
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In general, a control option that reduces overall HAP
emissions to the greatest extent should be identified as MACT;
however, there may be occasions when the hazard to human health
and the environment of a particular HAP warrants the selection of
a MACT specifically for the control of that HAP. Identification
of more than one control technology may be necessary when an
emission unit has multiple HAP emissions. An owner or operator
is advised to consult with the reviewing agency to determine if
this is the case. After this step is completed an owner or
operator should skip to Tier III of the analysis.
Tier II - Considering all control technology
Step 1 — List available control technologies
Using available information, the owner or operator or
permitting agency should develop a list of control technologies
that have been successfully demonstrated in practice for similar
emission units. Similar emission units are discussed in more
detail in Section 3.4 of this chapter. In addition, the owner or
operator may wish to consider innovative technologies and
transfer technologies that might reasonably be applied to the
MACT-affected emission unit.
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Step 2 — Eliminate technically infeasible control technologies
All control technologies that could not be applied to the
MACT-affected emission unit because of technical infeasibility
should be eliminate from the list. An owner or operator should
be prepared to justify the elimination of a control technology in
the application for a MACT determination.
Step 3 — Conduct a costs, non-air quality health and
environmental impacts, and energy requirements analysis
The owner or operator or the permitting agency should
conduct a detailed analysis on all of the available control
technologies. The efficiency of each control technology in
reducing overall HAP emissions should be determined. A reviewing
agency may require an owner or operator to select MACT based on
the degree of emission reductions achieved for one or more
specific HAPs when the risk to human health and the environment
warrants establishing MACT emission limitations specifically for
these HAPs. Otherwise, MACT should be selected based on an
overall reduction of all HAP emissions. It should be noted that
the application of more than one control technology may be
necessary in order to address multiple HAP emissions.
After determining the control efficiency of each available
control technology, the owner or operator should identify the
control technology(s) that allows for a maximum degree of HAP
emission reductions with consideration to the costs of achieving
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such emission reductions, and the non-air quality health and
environmental impacts and energy requirements. This is the MACT.
See Chapter 3 of this guidance document for a more detailed
discussion of the costs, non-air quality health and environmental
impacts, and energy requirements analysis.
Tier
III — Establishing a MACT emission limitation
Step 1 — Establish a MACT emission limitation (MEL)
The owner or operator should determine the degree of
emission reduction that can be obtained from the MACT-affected
emission unit, if MACT is applied, and properly operated and
maintained. The MACT emission limitation should be based on an
overall reduction of all HAP emissions; however, if possible,
the efficiency of the MACT in reducing each potential HAP
emission should also be stated. The permitting agency will also
have the discretion to establish a MACT emission limitation for
an individual HAP when the risk to human health and the
environment warrants such an emission limitation, or when such a
limitation is necessary to make the overall HAP emission
limitation federally enforceable.
Chapter 4 discusses three ways to establish a MACT floor:
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using State and local regulations, control efficiencies and
emission reduction ratios. If State and local regulations are
used to establish the MACT floor, the MACT emission limitation
may be based on a specific emission limitation contained in a
regulation such as 10 Ibs/per gallon of coating applied. In
other cases, the regulations may be based on a specific design or
work practice. It may not be feasible to establish a specific
numerical or efficiency limitation, in such cases. If it is
infeasible to prescribe a specific emission limitation, The MACT
emission limitation should be based on the application of a
specific design, process, or control technology.
When control efficiencies are used to establish a MACT
floor, the MACT emission limitation (MEL) can be computed by
multiplying the efficiency of MACT by the uncontrolled emission
level (UCEL) of the emission unit as follows:
MEL = UCEL * MACT efficiency
The reader should refer to Section 4.4 for a definition of
uncontrolled emission level.
When the emission reduction ratio is used to determine the
MACT floor, the MACT emission limitation can be computed by
multiplying the uncontrolled emission level by the emission
reduction ratio of MACT using the following formula:
MEL = UCEL * (1 -
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Step 2 — Select a control technology to meet the MACT emission
limitation
Once the MACT emission limitation is established, the owner
or operator should determine the control technology that should
be applied to the emission unit that will allow the source to
meet the required MACT emission limitation. In many cases, this
will be the MACT technology. However, in some cases, the
emission unit may already be controlled to a some extent with an
existing control devise. The owner or operator could demonstrate
that using additional control strategies in combination with
existing controls will allow the emission unit to achieve the
required emission reductions. For instance, an emission unit may
currently be controlled with a baghouse. MACT for the emission
unit may be an electric static precipitator. The emission unit
may be able to meet the MACT emission limitation by installing a
series of baghouses in lieu of the electric static precipitator.
The amount of additional control required (ARC) can be computed
by subtracting the MACT emission limitation from the controlled
emission level (CEL) (See Section 4.4 for the definition of CEL)
as follows:
ARC = CEL - MEL
If ARC is equal to zero or is a negative number, no additional
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control is required. The emission unit is currently meeting the
criteria for MACT. If ARC is a positive number, the owner or
operator must reduce hazardous emissions by this amount. The
reader is referred to Section 4.4 for a definition of controlled
emission level.
Owners or operators are reminded that the application of a
case-by-case MACT to an emission unit does not exempt that owner
or operator from complying with any future emission standards
affecting that emission unit. The MACT floor emission limitation
as calculated on a case-by-case basis should be considered only a
relative indicator of the future MACT emission standard. Changes
in technology or application of controls to under-controlled
sources may shift the MACT floor to a higher control level,
additional emissions information may be available that generates
a different level of control for the MACT floor, or a control
technology that is more effective in controlling HAP emissions
may be selected based on the relative cost of applying that
technology on a nationwide basis. Owners or operators may wish
to consider applying control strategies that exceed the MACT
floor requirement.
Step 3 — Establish appropriate monitoring, reporting and
recordkeeping parameters
The owner or operator or the permitting agency should
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identify monitoring parameters to assure compliance with the MACT
emission limitation. Section 2.2 of Chapter 2 discusses
compliance provisions in greater detail.
Step 4 — Prepare application for a Title V permit or Notice of
MACT Approval
Once a control technology(s) is identified and the MACT
emission limitation(s) is established, the owner or operator
should prepare an application for a Title V permit or Notice of
MACT Approval consistent with the procedures contained in 40 CFR
Part 63, Subpart B.
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3.3 Determining the MACT-affected emission unit
The purpose of a case-by-case MACT determination is to
determine that all affected emission points will meet a MACT
emission limitation. A MACT emission limitation will be
established for an emission unit known as the MACT-affected
emission unit. The MACT-affected emission unit could either be a
single affected emission point, or a combination of affected
emission points.
There are four basic principles to follow when designating
the MACT-affected emission unit. The principles can be
summarized as follows: 1) When a relevant Section 112(d) or
Section 112(h) standard has been proposed, the owner or operator
and the permitting agency should refer to the relevant standard
to determine the MACT-affected emission unit; or, (2) When a
source category on the source category list is designated as a
specific piece of equipment, the MACT-affected emission unit is
that piece of equipment or apparatus; or, (3) The EPA's Office
of Air Quality Planning and Standard's should be consulted to
determine if a suggested method for grouping of affected emission
points is available; or, (4) Emission points should be combined
into a single MACT-affected emission unit when the combination of
points leads to a much more cost-effective method of control, and
achieves a greater degree of emission reductions when compared to
point-by-point compliance.
The best indicator of how a source category may be regulated
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after the promulgation of a relevant standard is found in a
proposed standard. For this reason, EPA believes that owners or
operators and permitting agencies should follow the guidelines in
the proposed standard for determining the MACT-affected emission
unit for a Section 112(j) MACT determination. Although there may
be no proposed standard for the source category, and EPA may have
missed the promulgation deadline for that source category,
information on the source category may have been collected which
allows EPA to recommend a specific method for determining the
emission unit for a Section 112(j) MACT determination.
Therefore, EPA should be consulted before attempts are made to
define the MACT-affected emission unit on a case-by-case basis.
EPA can be contacted through the Control Technology Center
Hotline operated by the Office of Air Quality Planning and
Standards at (919)-541-0800.
When an affected emission point(s) is associated with a
piece of equipment or apparatus specifically listed on the source
category list, that affected emission point(s) is the MACT-
af fected emission unit. The source category list (See Appendix
D) contains sources that are defined by a manufacturing or
process operation, or as an individual piece of equipment. In
developing the source category list, EPA determined that some
individual pieces of equipment have the potential to emit major
amounts. For example, under the fuel combustion industrial
grouping, stationary internal combustion engines are listed as a
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source category of major sources. When a source category is
designated by a single type of apparatus, the EPA believes that
the intent is for emission limitations and requirements to be
placed on that specific piece of equipment. As such, if a
Section 112(j) determination is conducted for any one of these
source categories, the specific piece of equipment or apparatus
should be designated as the MACT-affected emission unit. Other
examples of apparatus that are listed as a source category or
major sources are municipal waste incinerators, process heaters,
and stationary turbines. The owner or operator should review the
list found in Appendix D to determine other source categories
that could be defined as the MACT-affected emission unit.
Otherwise, individual affected emission point can be
considered a MACT-affected emission unit, or a group of affected
emission points can be combined into one affected emission unit.
There are several ways in which emission points could be combined
to form an emission unit. A few points could be combined, an
entire process unit could be included in the MACT-affected
source, or the MACT-affected source could be as large as the
source category boundary.
For example, a single emission point such as a storage tank
could be consider the MACT-affected emission unit. Or, emission
points from a distillation column, a condenser and distillate
receiver could be consolidated into one emission unit. Larger
groupings of emission points maybe appropriate when a single
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control technology can be used to control the aggregation or when
a pollution prevention or waste reduction strategy is considered.
For instance, the entire wastewater treatment operation could be
considered one emission unit. Collectively, a single steam-
stripper could be used at the beginning of the operation to
remove HAPs from the wastewater and prevent downstream emissions
from occurring. Another example is illustrated with a surface
coating operation. Rather than individually controlling the
emissions from a spray booth, flash-off area, and bake oven,
switching to a water-based paint could reduce emissions from all
of these emission points.
Another reason to combine affected emission points into a
single emission unit is that many major sources are already
subject to regulation under 40 CFR Part 60 and Part 61. In
promulgating these standards, "affected facility" definitions
were developed to designate the apparatus to which a standard
applies. It may make sense to use these same boundaries to
designate the "MACT-affected emission unit" subject to a MACT
determination. It should be noted that a particular piece of
apparatus or equipment should not be excluded from a MACT
determination because of an applicability "cut-off" established
under a Part 60 or Part 61 regulation.
Emission points could be consolidated into an emission unit
that is as large as the source category boundary for several
reasons. First, the MACT floor needs to be calculated
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specifically for the MACT-affected emission unit. The
information that is available to calculate the MACT floor may
only be available for the source category as a whole, not
individual points within the category. Also, the operations of
some source categories are quite variable. Either the nature of
the process requires a large latitude of flexibility in
establishing the emission unit that should be controlled, or the
types of facilities within the category are so diverse that it
only makes sense to compare the existing sources on a source
category wide level. In these instances, a source category wide
MACT-affected emission unit could allow some emission points to
be under controlled while others are controlled to a level that
would exceed the level of control that would be placed on that
individual point through the application of MACT. Permitting
agencies are cautioned that it would be generally inappropriate
to include emission points associated with equipment leak
emissions into such a MACT-affected emission unit.
There are some situations which would not make the
combination of emission points reasonable. First, the combined
emission unit can not generate an emission unit that is so unique
that it precludes comparing the emission unit to other sources in
the source category. Second, the combining of emission points
should reduce emissions from all of the affected emission points
within the MACT-affected emission unit through use of a control
technology that affects all of those emission point, or involves
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recycling or reuse, or constitutes an overall source reduction
strategy as defined in the Pollution Prevention Act, P.L. 101-
503. The types of activities that would be considered pollution
prevention or source reduction measures include changes in
technology, process or procedures, reformulation or redesign of
products, and substitution of raw materials. A decrease in
production rate alone would not constitute a source reduction
strategy unless the rate reduction was associated with a
pollution prevention measure such as increasing efficiency of the
operation.
Determining the MACT-affected emission unit on a case-by-
case basis is a complex undertaken. While this document includes
this step as a separate component of the Tier I approach, in
actual practice the identification of methods to control specific
groups of emission units will be an integrated process with the
identification of control technology options. Some aggregations
of emission points may be inappropriate because the information
available to calculate the MACT floor would dictate combining
emission points into certain emission units, or because controls
applied to the unit would not achieve a MACT level of control
when compared to point-by-point compliance or some other
combination of emission units. Appendix A provides an example of
ways in which available control technologies would affect the
aggregation of emission points into an emission unit.
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3.4 Similar Emission Units
When an owner or operator constructs or reconstructs an
emission unit a MACT emission limitation(s) must be meet based on
a new source level of control. This emission limitation should
be based on the emission reductions achieved by the best
controlled similar source. Also, when a MACT floor can not be
determined for an existing emission unit during Tier I of the
MACT analysis, the owner or operator is required to identify all
available control technologies, using available information, that
could be applied to a similar emission unit. For the purposes of
case-by-case MACT determinations under Section 112(j), a similar
source is a similar emission unit. If two emission units have
similar emission types and could be controlled using the same
type of control technology, those emission units would be
considered similar for the purposes of a case-by-case MACT
determination. For instance, plastic extrusion is used in both
the plastic manufacturing industry and graphic art industry. The
emissions from these industries may be similar and be amendable
to the same type of control technology.
The EPA developed an emission classification system to be
used for determining emission types for case-by-case MACT
determination. The five emission classifications are as follows:
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Process vent or stack discharges - the direct or indirect
discharge of an organic liquid, gas, fume, or particulate by
mechanical or process-related means. Examples would be
emission discharges from columns and receiving tanks from
distillation, fractionation, thin-film evaporation, solvent
extraction, air and steam stripping operations, absorbers,
condensers, incinerators, flares, and closed-looped
biological treatment units.
Equipment leaks - fugitive emissions from the following
types of equipment: valves, pumps, compressors, pressure
relief devices, sampling connection systems, open-ended
valves and lines, flanges, agitators, sampling connection
systems, and valve connectors.
Evaporation and breathing losses - emissions from storage or
accumulation of product or waste material; for example:
stationary and mobile tanks, containers, landfills, and
surface impoundments, and pilings of material or waste.
Transfer losses - emission of an organic liquid, gas, fume,
vapor or particulate resulting from the agitation of
material during transfer of the material from one unit to
another. Examples of such activities are filling of mobile
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tanks, dumping of coke into coke quench cars, transfer of
coal from bunker into larry car, emptying of baghouse
hoppers, and sludge transfer.
Operational losses - emissions resulting from the process
operation which would result in fugitive emissions if
uncontrolled by hoods or vacuum vent, or other vent systems.
Examples of operation loses are emission resulting from
spray coating booths, dip-coating tanks, quenching towers,
lubricating stations, flash-off areas, or grinding and
crushing operations.
The classification scheme has been developed to serve as a
general guide in identifying available control options. When
using the list of classifications, consideration should be given
to the concentration and the type of constituents of a gas
stream. While two pieces of apparatus are classified within the
same emission type, this does not automatically mean that the
emission points can be controlled using the same type of control
technology. For instances, storage tanks and landfills are both
listed in the evaporation and breathing losses classification,
but it is unlikely that a storage tank and landfill would be
controlled with the same technology. In order for an emission
unit to be considered similar it must fit both criteria: have a
similar emission type and be controllable with the same
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technology.
Use of this classification system can be illustrated with an
owner or operator of a major source within the captan production
source category (a source listed on the source category list in
Appendix D,) who adds additional product accumulation vessels
(tanks) and additional pipes, pumps, flanges and valves to direct
the product to the tanks. After reviewing a database during
Tier I of the MACT analysis, the owner or operator determines
that there are no regulations controlling HAP emissions from
pumps within the source category; and, there is not enough
emission information available on other emission units within the
source category to calculate a MACT floor. During Tier II of the
analysis, the owner or operator discovers that the Synthetic
Organic Chemical Manufacturing Industry (SOCMI) source category
has regulations for controlling equipment leaks. Because the
pipes, pumps, and flanges all have equipment leak emissions, the
emission units in the SOCMI source category would be considered
similar emission units; and, the regulations for SOCMI equipment
leaks should be considered for the control of the MACT-affected
emission unit during Tier II of the analysis. Identification of
a similar emission unit does not mean that the controls will
automatically be applied to the MACT-affected emission unit.
Costs, non-air quality health and environmental impacts, and
energy requirements should be used to assess the technologies
ability to meet MACT criteria.
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3.5 Subcategorization
When the source category list was developed, sources with
some common features were grouped together to form a "category".
During the standard-setting process, EPA may find it appropriate
to combine several categories or further divide a category to
distinguish among classes, types, and sizes of sources. EPA
chose to establish broad source categories at the time the source
category list was developed because there was too little
information to anticipate specific groupings of similar sources
that are appropriate for defining MACT floors for the purpose of
establishing emission standards.
The broad nature of some source category descriptions may
pose some difficulty in establishing an appropriate MACT emission
limitation for a MACT-affect emission unit on a case-by-case
basis. Subcategorization within a source category for the
purposes of a case-by-case MACT determination should be
considered only when there is enough evidence to clearly
demonstrate that there are air pollution control engineering
differences. Criteria to consider include process operations
(including differences between batch and continuous operations),
emissions characteristics, control device applicability and
costs, safety, and opportunities for pollution prevention.
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Chapter 4.0
The MACT Floor Finding
During Tier I of the MACT analysis, an owner or operator or
the permitting agency is required to make a positive or negative
MACT floor finding. A positive finding would be made if there is
enough information to determine a emission control level that is
at least equal to the MACT floor. A negative MACT floor finding
would be made if: (1) the MACT floor equals "no control"; (2) a
MACT floor can not be determined due to the nature of the
pollutant or process; or, (3) there is not enough emissions
information to compute a MACT floor.
The EPA recognizes that computing the MACT floor for a MACT-
affected emission unit may be time consuming and burdensome for
the owner or operator or the permitting agency. To avoid
calculating a specific emission control level that equals the
MACT floor, while still making a positive MACT floor finding, the
owner or operator can establish a MACT emission limitation based
on use of the very best emission control technology. The very
best emission control technology will meet or exceed the level of
emission reduction required by a MACT floor finding. Owners or
operators and the permitting agency should refer to existing EPA
control technology guidelines (CTG), background information
documents (BID,) existing New Source Performance Standards (40
CFR Part 60,) or existing National Emission Standards for
Hazardous Air Pollutants (40 CFR Part 61) to determine if these
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information sources can help to establish a particular control
technology as the best for controlling HAP emissions from the
MACT-affected emission unit. An owner or operator may also
establish a control technology as the very best, by choosing the
control technology that achieves a maximum degree of reduction in
emissions of the HAPs with consideration to the costs, the non-
air quality health and environmental impacts, and energy
requirements. Minimal consideration should be given to cost
impact in such an analysis.
An owner or operator could also avoid calculating a specific
MACT floor by referring to existing databases to document whether
a MACT determination for another similar emission unit in the
source category has recently been made. This MACT determination
could be used to establish the MACT floor for the MACT-affected
emission unit provided there is no reason to believe that the
control technology no longer represents MACT. This was
previously discussed in Section 3.1.
Because the above methods will not always clearly identify a
control technology or emission limitation that meets the MACT
floor, an owner or operator or the permitting agency may be
required to review existing emissions information to calculate a
specific MACT floor. Section 4.1 of this chapter discusses the
calculation procedure for determining an "average emission
limitation". This procedure establishes a hierarchical system
for determining the average emission limitation using the
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arithmetic mean, median or mode.
Using the calculation procedures discussed in Section 4.1,
the EPA has established three acceptable methods for determining
a MACT floor. If the emissions information is available, all
three methods should be considered before the owner or operator
concludes that a MACT floor can not be found. The three methods
include using: (1) existing State and local air toxic control
regulations; (2) control efficiency ratings; or (3) emission
reduction ratios. Figure 3 lists these methods. Each of these
methods is discussed in greater detail later in this Chapter.
The first method compares air pollution regulations in
different States. This method is likely to require the least
amount of data search and analysis. The second and third methods
base the MACT floor on a level of emission reductions, allowing
the MACT-affected emission unit more flexibility in determining
control technologies to meet the MACT floor. The second method
is applicable only when the control technologies under
consideration can be assigned an efficiency rating for HAP
emission reductions. This is most-likely to occur with add-on
control devises. The third method can be used for add-on control
devises, work practices, recycling, reuse or pollution prevention
strategies. Depending on the format of available information, a
hybrid of the three approaches may be necessary.
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Acceptable Methods for
Determining the MACT floor
Emission Reduction Ratios
Efficiency Ratings
Existing State or Local Air Pollution Regulations
Other Acceptable Methods
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4.1 Calculation of the MACT Floor
Section 112(d) of the Act instructs EPA to set emission
standards for new sources based on the emissions control achieved
by the best controlled similar source and to set emission
standards for existing sources based on an average emission
limitation achieved by the best performing 12% of existing
sources or best performing five sources in the source category.
For new sources the direction provided by the Act is relatively
clear. For existing sources, further clarification is required
by EPA to determine how an average emission limitation should be
computed.
The word average can have several different meanings,
including arithmetic mean, median and mode. EPA has developed
the following hierarchy for determining the average emission
limitation that is equal to the MACT floor. First, if the
emissions data that is to be used to calculate the floor is in
the form of a numerical expression, (i.e. 95% reduction), the
MACT floor should be determined by taking the arithmetic mean of
the best performing 12% of existing sources or the best
performing five sources. An arithmetic mean is calculated by
summing all of the data and dividing by the number of data
elements in the calculation. The following example illustrates
this concept:
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Example \
The following emission limitations are representative of the
best performing 12% of existing source:
% reduction
99 Average emission limitation =
99
95 656/7 = 93.7%
93
92
89
89
Total 656
# of sources = 7
Under some circumstances the arithmetic mean results in a
number that may not correspond to the application of a specific
control technology. For instance suppose the arithmetic mean of
emission limitations of the best performing 12% of exist sources
is equal to 92.3%. Application of control Technology X would
provide a source 91% control, while application of Technology Z
would limit the source's emissions by 96%. In most cases, when
the arithmetic mean can not be specifically achieved by the
application of a control technology, the MACT floor should be
elevated to the level of control associated with the control
technology that exceeds the MACT floor. In Example 1, the MACT
emission limitation should be no less stringent than 95% control.
This concept would not make sense if there is a large discrepancy
between the amount of emission reductions that can be achieved by
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available control options. This is illustrated with the
following example:
Example 2
An arithmetic mean is computed for the best performing
12% of storage tanks. There are 10 sources among the best
performing 12% of storage tanks. Two tanks are controlled
by 99%, the remaining 8 tanks are not controlled. The
emissions limitations considered in the floor calculation
are:
% reduction
99 ...
99 average emission limitation =
0
0 19.8% reduction
0
0
0
0
0
0
Total 198
# of sources = 10
In this example, no technology corresponds to 19.8% control, and
it might be inappropriate to elevate the MACT floor to 99%
control.
If there is a large discrepancy between the amount of
emission reductions that can be achieved by available control
options, the median should be used in lieu of the arithmetic mean
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to determine the average emission limitation equal to the MACT
floor. A median is the value that falls in the middle of a set
of numbers when those numbers are arranged in an increasing order
of magnitude; in other words, there will be an equal number of
values above and below the median. If the middle falls between
two values, the median is equal to the arithmetic mean of those
two numbers. This situation will occur when there is an even
number of values in the set of numbers. When computing the
average emission limitation for the best performing 12% of
existing sources, the median will always be equal to the lowest
emission limitation achieved by the best 6% of sources in the
source category. For example:
Example 3
There are 84 sources in the source category. The
number of sources in the best performing 12% of source is
equal to 10. The median is to be computed for the following
emissions data:
% reduction
24
26 There are a total of 10 numbers
30 the median would be the arithmetic
30 mean of the 5th and 6th numbers
33 in the column.
40
56 median = (33 + 40)/2 = 36.5
88
93
99
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Like the computation of the arithmetic mean, the value
obtained for the median may not always correspond to a specific
control technology. If there is a control technology that
obtains slightly greater emission reduction than the median, the
MACT floor should be based on that control technology. For
instances, in Example 3, the MACT floor would be equal to 40%
emission reductions. This value coincides with the lowest
emission limitation achieved by the best performing 6% of
sources. However, if there is a large discrepancy between the
control technologies used to establish a median such that no
technology could realistic obtain a reduction close to the
median, the mode should be used to calculate the MACT floor.
A mode is the most frequent occurrence among a set of data.
In Example 1, the mode would be 99% emission reductions. In
Example 2, the mode would be equal to 0% emission reductions; and
the mode in Example 3 would be 30.
The mode may also be used as a method to compute an average
emission limitation if the emissions data for a source category
is not based on a numerical number. This could occur if sources
were regulated by several different equipment or work practice
standards. Unless a specific level of emission reduction can be
associated with each different standard or unless the standards
can be ranked in some order of increasing level of control, an
arithmetic mean and median can not be calculated. A mode could
be used if one of the control options was used more frequently by
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one of the best performing 12% of existing sources. For example:
Example 4
There are 44 tanks in the source category. 5 sources would
be among the best performing 12% of existing sources. These
five tanks are subject to the following regulations in the
source category:
3 of the 5 must be covered and vented to a carbon
canister;
2 of the 5 must use a fixed roof
The mode would be to cover and vent the tank to a carbon
canister.
The following sections of this chapter detail the three
acceptable methods for computing a MACT floor. It should be
noted that when the best controlled similar source is being
determined for a new or reconstructed source, all references to
using emissions information from within the source category
should be ignored. Identifying the MACT floor for constructed
and reconstructed major sources requires that the emission
information used to determine the best controlled similar source
not be limited to within the source category. Readers are
referred to Section 3.4 of this chapter for a definition of
similar emission unit.
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4.2 Method 1 - Computing the MACT Floor Using Existing State and
Local Regulations
The steps for computing a MACT floor using this method are
listed in Figure 4. The following describes these steps.
Step (A) Conduct a geographical survey
Determine the number of existing similar emission units in
the source category, and conduct a survey to determine the
geographical location of these similar emission units. Group the
emission units according to the state or locality in which they
are located.
Step (B) Review State or local air pollution regulations
Review the different State or local air pollution control
regulations that are applicable to the emission unit in each
State or locality where the emission unit is located.
Step (C) Rank the State or local air pollution regulations
For the State and local regulations identified in Step B,
rank the regulations in order of stringency. The regulations
that require the greatest level of control should be listed
first.
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Figure 4 proposal
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Using State or Local
Air Pollution Regulations
to Compute the MACT Floor
Step A Conduct a Geographical Survey
Step B Review State and Local Air Pollution Regulations
Step C Rank the Regulations according to Stringency
Step D Determine the Percentage of Emission Units Complying with
each Stringency Level
Step E Determine MACT Floor
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Step (D) Determine the number of emission units regulated by
each stringency level.
For each level of stringency identified in Step (C), a
percentage of emission units required to comply with the
regulations should be computed.
Step (E) Make a MACT floor finding
For constructed or reconstructed major source, the MACT
floor will equal the most stringent State or local regulation
applying to a similar emission unit. For a modified major
source, the MACT floor will either be equal to the arithmetic
mean of the best 12% of existing emission units in the source
category, or the best 5 existing emission units in the source
category. If the arithmetic mean can not be calculated, the
median or mode should be used to compute the MACT floor for
existing sources.
Figure 5 illustrates the following example of this concept:
In Step (A), the owner or operator determines that there are 42
similar emission units in the MACT-affected emission unit's
source category. Sixteen of the sources are located in State A,
five in State B, three in State C, and 18 in State D. A specific
numerical value can not be determined for all of these
regulations, but it is possible to list the regulations in order
of stringency. Upon reviewing the regulations in these four
States, it is determined that States A and B have the most
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Figure 5
Evaluation of State Regulations
for Emission Unit X
STATE
A
B
C
D
TOTAL
STRINGENCY*
1
1
2
3
# OF SOURCES
16
5
3
18
42
Total # of emission units
# of emission units within the top
6% of existing emission units
Stringency level top 6 emission
units must comply with
MACT floor
= 42
=3 (42 * 0.06)
= 1
regulations
in State A or B
* Stringency is rated from the most stringent State regulation
beginning at 1 and increasing in number as the regulation is
rated less stringent.
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stringent regulations for this source; and, they are equally
stringent. These State regulations are followed in stringency by
State C. State D is the least stringent state; there are no
regulations and the sources are uncontrolled.
State A and B regulate 50% of the sources. Using the median
to compute the MACT floor, the MACT floor would be equal to the
least stringent regulations governing the most strictly regulated
3 sources (42 * 0.06 rounded to the next largest whole number.)
In this case, the MACT floor would be equal to either State A or
State B's regulations.
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4.3 Method 2 — Computing the MACT Floor using Control
Efficiency Ratings
To use this method to calculated the MACT floor, the owner
or operator will evaluate emission units within the source
category that use add-on control devices or other methods whose
HAP control efficiencies have been clearly demonstrated. See
Figure 6 for a summary table of the steps for using the control
efficiency rating. The MACT floor and MACT emission limitation
can be computed as follows:
Step (A) Determine HAP emission reduction efficiency for each
control device.
For each similar emission unit in the source category,
the ability of each control technology to reduce HAP emissions
should be determined as a percentage of reduction efficiency.
Acceptable methods for determining the efficiency rating are:
1) Equipment vendor emission data and guarantees;
2) Federal and State enforceable permits limits on
operation of the control technology;
3) Actual reported efficiency from the similar emission
unit.
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Using Control Efficiency Ratings
to Compute the MACT Floor
Step A Determine Efficiency of Control Technology used by other
Emission Units.
Step B Determine the MACT Floor.
Step C Compute an Uncontrolled Emission Level(UCEL) for the
MACT-Affected emission unit.
Step D Compute a Controlled Emission Level (CEL) for the
MACT-affected emission unit.
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Step (B) Calculate the MACT floor
For new and reconstructed emission units, the MACT floor
equals the level of emission reductions that can be obtained by
the control technology with the highest emission reduction
efficiency. For existing emission units, the MACT floor equals
the arithmetic mean of the best five or highest 12% of control
efficiency ratings. Or, if the median is used the MACT floor
equals the lowest control efficiency rating achieved by the best
6% of sources if there are greater than 30 sources in the source
category; or, the MACT floor equals the lowest control efficiency
rating among the best 3 sources if there are less than 30 sources
in the source category. Under most circumstances, it should not
be necessary to use the mode to compute an average emission
limitation; however, if it is used, the MACT floor would be
equal to the most frequent control efficiency rating among the
best performing 12% of existing sources or the best performing
five sources.
Step (C) Determine the uncontrolled emission level for the MACT-
affected emission unit
Use the same procedure outline in Step D of Method 3 in
Section 4.4 of this Chapter.
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Step (D) Determine a controlled emission level for the MACT-
affected emission unit
Use the same procedure outlined in Step E of Method 3 in
Section 4.4 of this chapter.
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4.4 Method 3 - Computing the MACT floor Using Emissions
Reduction Ratios (ERR)
The emission reduction ratio is a fraction of uncontrolled
emissions to controlled emissions. The MACT floor is computed
using the emission reduction ratios. To compute the emission
reduction ratio for each emission unit, the owner or operator
must review emissions data or other information to determine
uncontrolled and controlled emissions levels for these units.
The step-by-step process is detailed below and summarized in
Figure 7.
Step (A) Compute an uncontrolled emission level (UCEL) for each
similar emission unit in the source category.
The uncontrolled emission level is the annual sum of all air
emissions for every HAP that could be emitted from all emission
points in the absence of control technologies given the maximum
design capacity used by the similar emission unit within the five
year period proceeding the date of application submittal. For
new emission units, uncontrolled emissions should include the
current design specifications for that equipment in an
uncontrolled state.
For example, in 1992, an owner and operator of a major
source used trichloroethylene in a degreasing operation. In
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Using the Emission Reduction Ratios
to Compute the MACT Floor
Step A Compute an Uncontrolled Emission Level (UCEL) for each
emission unit.
Step B Compute a Controlled Emission Level (CEL) for each emission
unit.
Step C Compute an Emission Reduction Ratio (ERR) for each emission
unit.
ERR = UCEL - CEL
UCEL
Step D Determine the MACT Floor.
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1993, the owner or operator switched to a water-based solvent in
the degreasing operation. In 1994, the owner or operator changed
to using a low-VOC based solvent because the water-based solvent
performed poorly. If a Section 112(j) MACT determination is
conducted for the emission unit, the uncontrolled emission level
would be computed using trichloroethylene in the calculation. In
1995, after already receiving the Title V permit, the owner or
operator adds a degreaser (a new emission unit) that uses water-
based solvents in the degreasing operation. The uncontrolled
emissions for this affected emission unit would be based on the
design specifications associated with the water-based solvent.
The uncontrolled emission level should be based on tons/yr
unless the nature of the process is more accurately reflected by
computing the mass per production unit. Acceptable methods for
making this calculation are:
(a) Engineering calculation using material balance or
emission factors;
(b) Actual emission data for the similar emission unit;
(c) Average annual hourly emission rate multiplied by hours
of operation;
(d) Emission limits and test data from EPA documents,
including background information documents;
(e) Equipment vendor emission data and guarantees;
(f) State emission inventory questionnaires for comparable
sources;
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(g) Federal or State enforceable permit limits; or,
(h) For equipment leaks use, "Protocols for Generating
Unit-Specific Emission Estimates for Equipment Leaks of
VOC and VHAP."
Step (B) Compute a controlled emission level (CEL) for each
similar emission unit or existing emission unit within the source
category.
The controlled emission level is the sum of all air
emissions for every HAP that could be emitted from all emission
points given the maximum design capacity currently in use by the
similar emission unit taking into consideration the application
of existing control technologies and federally enforceable limits
(or for the emission unit undergoing the review, those controls
that will be federally enforceable if approved as MACT) that have
been placed on HAP emissions from that emission unit. This
figure should be based on tons/year, unless the nature of the
process is more accurately reflected on a mass per production
unit basis. Acceptable methods for making this calculation are:
(a) Engineering calculations using material balance or
emission factors;
(b) Any reported or measured emission that offers a true
representation of yearly emissions;
(c) Average annual hourly emission rate multiplied by hours
of operation;
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(d) Emission limits and test data from EPA documents,
including background information documents;
(e) Equipment vendor emission data and guarantees;
(f) State emission inventory questionnaires for comparable
sources;
(g) Federal or State enforceable permit limits; or,
(h) For equipment leaks use, "Protocols for Generating
Unit-Specific Emission Estimates for Equipment Leaks of
VOC and VHAP."
Step (C) Compute the emission reduction ratio (ERR) for each
emission unit:
ERR = UCEL - CEL
UCEL
Step (D) Determine the MACT floor.
For new or reconstructed sources the MACT floor would be
equivalent to the highest ERR. For existing sources, the MACT
floor equals the arithmetic mean of the best five or best 12% of
ERRs. If the median is used, the MACT floor equals the lowest
ERR among the best 6% of ERRs or the best three ERRs depending on
the number of sources in the source category. If the mode is
used, the MACT floor equals the most frequently occurring ERR
among the best performing 12% of sources or best 5 sources
depending on the number of sources in the source category.
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For example, suppose a major source determined that there
are four emission units in the top 12% of existing emission units
for the source category. These four emission units had emission
reduction ratios of 0.90, 0.92, 0.93, and 0.99. The control
technologies used by these best performing 12% of similar source
are a wet scrubber, a solvent change, a condenser, and an
incinerator. The arithmetic mean for these values equals 0.935.
If this value does not correspond to the application of a
specific control technology, the MACT floor would be equal to an
emission reduction ratio of 0.99. If it is determined that
elevation of the MACT floor to this level is infeasible, then the
median should be computed for these sources. The median would be
equal to best performing 6% of sources or the lowest of the
highest two emission reduction ratios. This is equal to 0.93.
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4.5 Exceptions Emission Reduction Ratios
In most circumstances the emission reduction ratio, is a
reliable method for calculating the MACT floor. However, there
are some circumstances when a very low emission reduction ratio
could be computed for a well-controlled emission unit. This may
occur if pollution prevention strategies are used for greater
than five years at the major source, or a process has an
inherently low potential to emit hazardous air pollutants. The
owner or operator could be reducing emissions to the maximum
extent possible without being able to credit the pollution
prevention strategy in computing the uncontrolled emissions. The
uncontrolled and controlled emission rate could be nearly the
same, causing the emission reduction ratio to be a very low
number. A reviewing agency should keep such situations in mind
when making a MACT determination. In such instances, the
pollution prevention method should not be eliminated as a
candidate to meet the MACT floor.
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4.6 Other Methods to Compute the MACT Floor
As future MACT standards are proposed or promulgated for
different source categories, more methods for determining the
MACT floor could be developed. The reader is referred to the
Federal Register to locate any other methods for calculating the
MACT floor that have been approved by the EPA and used in
developing a MACT standard under Section 112(d) or 112(h) of the
Act.
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Chapter 5
Costs, Non-air Health
and Environmental Impacts,
and Energy Requirements
Section 112(d) of the Act specifies that if control
technology alternatives are being considered to establish an
emission standard•that would result in emission limitations more
stringent than the emission "floor"; or, if insufficient data
exists to specify an emission limitation based on the MACT floor,
then control technology alternatives must be evaluated by
considering costs, non-air quality health and environmental
impacts, and energy requirements associated with the expected
emission reductions.
The costs, non-air quality health and environmental impacts,
and energy requirements discussed below are illustrative only and
are not intended as an exclusive list of considerations for MACT
determinations. Some of these factors may not be appropriate in
all cases, while in other instances, factors which are not
included here may be relevant to the MACT determination. The
discussion does not address the evaluation of each factor nor the
weighing of any factor relative to another. Such determinations
should be made on a case-by-case basis by the owner/operator and
permitting agency. For the purpose of this discussion, terms
such as "emission control system" or "MACT system" refer to
design, equipment, or operating standards and inherently less
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polluting processes, as well as add-on control equipment.
In general, the impact analyses for MACT determinations
should address the direct impacts of alternative control systems.
Indirect energy or environmental impacts are usually difficult to
assess, but may be considered when such impacts are found to be
significant and quantifiable. Indirect energy impacts include
such impacts as energy to produce raw materials for construction
of control equipment, increased use of imported oil, or increased
fuel use in the utility grid. Indirect environmental impacts
include such considerations as pollution at an off-site
manufacturing facility which produces materials needed to
construct or operate a proposed control system. Indirect impacts
generally will not be considered in the MACT analysis since the
complexity of consumption and production patterns in the economy
makes those impacts difficult to quantify. For example, since
manufacturers purchase capital equipment and supplies from many
suppliers, who in turn purchase goods from other suppliers,
accurate assessment of indirect impacts may not be possible. Raw
materials may be needed to operate control equipment, and
suppliers of these resources may change over time. Similarly, it
is usually not possible to determine specific power stations and
fuel sources which would be used to satisfy demand over the
lifetime of a control device.
In most cases, duplicative analyses are not required in
preparing the MACT impact analyses. Any studies previously
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performed for Environmental Impact Statements, water pollution
permits, or other programs may be used when appropriate;
however, the permitting agency may consider any special economic
or physical constraints which might limit the application of
certain control techniques to an existing emission unit, such as
retro-fitting costs that would not be borne by a new unit, or the
remaining useful life of the emission unit. The result may be
that the level of control required for an existing emissions unit
may not be as stringent as that which would be required if the
same unit were being newly constructed at an existing plant or at
a "greenfield" facility. However, in no event shall the level of
control yield an emission limit less stringent than the MACT
floor when information is available to compute the MACT floor.
5.1 Cost Impacts
Cost impacts are the costs associated with installing
operating, and maintaining alternative emission control systems
(add-on emission control devices or process changes.) Normally,
the submittal of very detailed and comprehensive cost data is not
necessary. Presentation of the quantified costs of various
emission control systems (referred to as control costs,) coupled
with quantities of HAP emission reductions associated with each
of the emissions control systems, is usually sufficient.
Once the control technology alternatives and emission
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performance levels have been identified, total capital investment
and total annual cost should be developed. Total capital
investment (purchased equipment plus installation) and total
annual costs of each emission control system should be presented
separately. Total annual coasts are comprised of operation and
maintenance costs ("direct annual costs",) administrative changes
("indirect annual costs"), plus overhead, taxes, insurance, and
capital recovery costs minus recovery credits (credit for product
recovery and by-product sales generated from the use of control
systems and other emission reduction credits.) These costs
should be reported in equal end-of-year payments over the time of
the equipment. Total annual costs should be reported on an
overall basis, as well as an incremental basis. The various
emission control systems should be presented or arrayed in terms
of increasing total annual cost. The incremental annual cost of
a particular emission control system is the difference in its
cost and the cost of the next less stringent control.
A method for determining the excessiveness or acceptability
of control costs is the comparison of the cost-effectiveness of
alternative control systems. Cost-effectiveness is the ratio of
total annual costs (calculated using the above guidelines) to the
total amount (tons or Mg) of HAP removed. Incremental cost
effectiveness is calculated using the same procedure as outlined
for calculating incremental annual cost. Generally, cost-
effectiveness falling within the range of previously acceptable
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MACT decisions are not considered excessive. Therefore,
consistency with the relative cost, or cost effectiveness, of a
past MACT determination for a similar source is an indication
that such a cost is reasonable for the MACT determination in
question.
For most MACT determinations, a cost analysis focusing on
incremental cost-effectiveness of various MACT alternatives is
sufficient. The analysis should include and distinguish the
various components used to calculate the incremental cost-
effectiveness of the control alternatives (i.e., lifetime of the
equipment, total annual costs, tons of total HAP removed, etc.).
If there is reason to believe that the control costs place a
significant burden on the entity being controlled, then the cost
analysis should include financial or economic data that provide
an indication of the affordability of a control relative to the
source. For example, if the per unit cost is a significant
portion of the unit price of a product or if the economic status
of the industry is declining, then the cost analysis should
present the relevant economic or financial data. Financial or
economic data should include parameters such as after-tax income
or total liabilities. An example of a financial criterion used
to determine affordability would be the ratio of a facility's
capital costs to the facility's parent company's total
liabilities. This ratio would provide an assessment of the
company's capital structure.
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5.2 Environmental impacts
The environmental impacts concentrate on collateral
environmental impacts due to control of emissions of the
pollutant in question, such as solid or hazardous waste
generation, discharges of polluted water from a control device,
visibility impacts (e.g. visible steam plume), or emissions of
other air pollutants. The applicant should identify any
environmental impacts associated with a control alternative that
has the potential to affect the selection or rejection of that
control alternative. Some control technologies may have
potentially significant secondary environmental impacts.
Scrubber effluent, for example, may affect water quality and land
use, and, similarly, technologies using cooling towers may affect
visibility. Other examples of secondary environmental impacts
could include hazardous waste discharges, such as spent catalysts
or contaminated carbon. Generally, these types of environmental
concerns become important when sensitive site-specific receptors
exist or when the incremental emissions reduction potential of
one control option is only marginally greater than the next most
effective option.
The procedure for conducting an analysis of environmental
impacts should be made based on a consideration of site-specific
circumstances. In general, the analysis of environmental impacts
starts with the identification and quantification of the solid,
liquid, and gaseous discharges from the control device or devices
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under review. Initially, a qualitative or semi-quantitative
screening can be performed to narrow the analysis to discharges
with potential for causing adverse environmental effects. Next,
the mass and composition of any such discharges should be
assessed and quantified to the extent possible, based on readily
available information. As previously mentioned, the analysis
need only address those control alternatives with any
environmental impacts that have the potential to affect the
selection or rejection of a control alternative. Pertinent
information about the public or environmental consequences of
releasing these materials should also be assembled. Thus, the
relative environmental impacts (both positive and negative) of
the various alternatives can be compared with each other.
Also the generation or reduction of toxic and hazardous
emissions other than those for which the MACT determination is
being made and compounds not regulated under the Clean Air Act
are considered part of the environmental impacts analysis. A
permitting authority should take into account the ability of a
given control alternative for regulated pollutants to affect
emissions of pollutants not subject to regulation under the Clean
Air Act in making MACT decisions. Consequently, the ability of a
given control alternative to control toxic or hazardous air
contaminants other than those for which the MACT determination is
being made, should be considered in the MACT analysis.
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4.3 Energy Impacts
Energy impacts should address energy use in terms of
penalties or benefits associated with a control system and the
direct effects of such energy use on the facility. A source may,
for example, benefit from the combustion of a concentrated gas
stream rich in volatile organic compounds; on the other hand,
extra fuel or electricity is frequently required to power a
control device or incinerate a dilute gas stream. If such
benefits or penalties exist, they should be quantified to the
extent possible.
In quantifying energy impacts, the application could
estimate the direct energy impacts of the control alternative in
units of energy consumption at the source (e.g., Btu, Kwh,
barrels of oil, tons of coal). The energy requirements of the
control options could be shown in terms of total and/or
incremental energy costs per ton of pollutant removed. In many
cases, because energy penalties or benefits can usually be
quantified in terms of additional cost or income to the source,
the energy impacts analysis can be converted into dollar costs
and, where appropriate, be factored into the cost analysis.
Indirect energy impacts (such as energy to produce raw
materials for construction of control equipment) are usually not
considered. However, if the reviewing agency determines, either
independently or based on a showing by the applicant, that an
indirect energy impact is unusual or significant, the indirect
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impact may be considered. The energy impact should still,
however, relate to the application of the control alternative and
not to a concern over energy impacts associated with the project
in general.
The energy impact analysis may also address the concern over
the use of locally scarce fuels. The designation of a scarce
fuel may vary from region to region, but in general a scarce fuel
is one which is in short supply locally and can be better used
for alternative purposes, or one which may not be reasonably
available to the source either at the present time or in the near
future.
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Chapter 6.0
Sources of Information
There are currently several programs under development to
house and disseminate toxics information. Some of these programs
are designed for specific, narrow purposes, while others are
employed in a broader range of uses. Many data collection
programs are designed for immediate interface with the AIRS
toxics program, which is currently under development.
The purpose of this chapter is to present various sources of
toxics information available in a database format. EPA believes
the requirements of 112(g) can be less burdensome to both
industry and States by employing a database system to calculate
the 12% floor which may involve using complex mathematical
algorithms and procedures.
BACT/LAER CLEARINGHOUSE INFORMATION SYSTEM (BLIS)
The BACT/LAER Clearinghouse, or the BACT/LAER Information
System (BLIS) is a database consisting of best achievable control
technology (BACT) determination information on specific sources,
to a process level. Database parameters include facility
information; process description; pollutant information; control
device type, installation date, efficiency; and calculation
method; and stack test information if it exists.
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Participation in BLIS is on a voluntary basis. If
participation in BLIS increases, it may be able to provide
sufficient information to determine the 12% floor with increasing
accuracy.
BLIS has undergone substantial revision. Additional fields
for use with toxics work have been added, changes to improve
"user-friendliness" of the system, such as menus and help screens
have been added, and BLIS is now available on the TTN Bulletin
Board.
JEI06 PROGRAMS
The Joint Emissions Inventory Oversight Group (JEIOG),
support for a data system for air toxics emissions inventories
focuses on the expressed reguirements of the urban area source
program (UASP, Section 112(k), of the CAAA) and the Great Waters
Program (GWP, Section 112(m)).
Under the JEIOG programs, there are both short term,
immediate needs and long-term needs. Since the UASP data
collection effort is scheduled to be completed by mid-1994, JEIOG
may need to select a system for immediately use by the Urban Area
Source Program.
Urban Area Source Program
The Urban Area Source Program (UASP) is collecting emission
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inventory data for use by mid -1994 to meet the CAA November 1995
date for development of a national strategy for control of HAP
emissions in urban areas. The inventory focuses on an adequate
number of urban areas to "understand the urban area source
problem." Baltimore, Chicago and Houston are the leading
candidate cities. Other cities could be added (such as
Milwaukee, Detroit or Seattle) as the resources become available.
The primary data need is for a single year "snapshot" of
emissions data for use in developing the national control
strategy plan. As of the date of this writing, JEIOG has not
committed to any single system for storing the UASP data. AIRS
is under consideration with other database systems.
Great Waters Program
The Great Waters program requires HAP emissions data for
most of the U.S. and portions of Canada. The Great Lakes region
probably requires the most attention. Biennial assessments as
reports to Congress are required under the Great Waters program.
The first report is expected in November 1993. Emissions
inventory data are used primarily for input to models for the
assessment of the relative atmospheric loading of toxic
pollutants into the Great Lakes and other waterways. Updates of
the emission inventory are anticipated to support the periodic
assessments and for input to refined models as they become
available.
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GENERIC ICR DATA (SECTION 114)
Under the Authority of Section 114, EPA developed a survey
to obtain the information needed to calculate regulatory floors
for both new and existing stationary sources (See Appendix ).
This survey is commonly referred to as a "generic ICR", or
information collection request. It is customized within narrow
parameters for each source category, and comes in both a "long
form" and a "short form". EPA sends the survey to facilities at
the time it initiates regulatory development for the affected
source category. In other words, the survey is not sent to
facilities in all source categories at the same time.
In the generic ICR, EPA requests information regarding each
compound identified as a HAP that is used in or emitted by any
operations, including fugitive emissions sources, occurring from
the source category at the facility.
Recipients of the form are required to fill out the
information request as completely as possible from existing
information. At a minimum, the facility must provide (1)
information of the presence of HAP emissions and (2) HAP emission
estimates based on previously obtained test data or on
engineering calculations provided there is a basis for such
calculations.
Since the Generic ICR data is collected by EPA from
industries, it is called "Agency data". As such, it can not be
used to update (or replace) existing data which was obtained from
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States, or "State data". The ICR data is currently stored and
analyzed on a commercial database software files. The Agency is
evaluating options to make the ICR data "safe" (without
confidential information) and accessible to States on a workfile
within AIRS/AFS.
XATEF: TOXIC EMISSION FACTORS
The requirements of the CAAA dictate immediate sampling and
analysis to obtain data for determination of emission factors.
These emission factors will be used to determine control
measures. EPA developed screening methods for the development of
air toxics emission factors, and applies the screening to test
results as they become available for use. The EPA is enhancing
the XATEF system for housing and manipulating the data. The
XATEF system is being redesigned to export toxic emission
factors, in a form similar to the AFSEF package for criteria
pollutants. The new system should be available by the fall of
1992.
The toxic emission factors available through the XATEF
system will be rated A (most reliable, based on several tests
meeting high confidence criteria) through E (least reliable,
having limited available information), similar to the way
criteria emission factors are presented in the AP-42.
Toxic emission factors are being developed for 400 toxic
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compounds, of which about 170 are on the list of 189 HAPs in
Section 112(b). About 40 of these have been targeted as
"critical" pollutants because they are found in a wide variety of
industries, and/or are especially toxic. This group of about 40
toxic compounds have a rating of A or B, enabling users to arrive
at the most accurate emissions estimates presently possible.
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AIRS/APS NATIONAL OPERATING PERMIT SYSTEM
The EPA promulgated a new part 70 of Chapter I of title 40
of the Code of Federal Regulations (CFR) on July 21, 1992,
establishing provisions for the Operating Permit Program, and the
minimum data elements of State operating permit programs. States
must develop and submit programs for issuing operating permits to
major stationary sources of HAPs.
The requirements of Section 112(g)(2) (A&B) are triggered by
the effective date of a permit program under Title V in any
State. Section 112(g)(3) states that "the Administrator (or the
State) shall establish reasonable procedures for assuring that
the requirements applying to modifications under this section are
reflected in the permit".
The most far-reaching program established under the CAAA is
that of a national operating permit program under Title V. The
National Air Data Branch (NADB) is developing a database as a
subsystem under AIRS/AFS to handle the new data coining in from
States Title V permit programs. This database is generally
referred to as the permit system. The permit system is under
design to provide much of the information needed for determining
the MACT floor both for case-by-case MACT determinations and for
MACT standards. It is expected that this system will become
available for use by the fall of 1993.
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AEROMETRIC INFORMATION RETRIEVAL SYSTEM (AIRS) TOXICS PROGRAM
The Aerometric Information Retrieval System (AIRS) was
designed and executed to accommodate the expansion of emissions
data. AIRS Facility Subsystem (AFS) is the stationary source
component of this system and replaced the old NEDS as the data
repository for point source data (e.g., electric utilities,
industrial plants and commercial enterprises). Enhancement of
AIRS continues to support the new programs designated by the
CAAA. The National Air Data Branch (NADB) is currently
considering data support of the requirements under Section 112
for HAP.
NATICH
The National Air Toxics Information Clearinghouse (NATICH)
has been established by EPA to support State and local agencies
in the control of non-criteria air pollutants. The NATICH
program has both a database and a reporting capability.
The database component of the clearinghouse contains
information on various air toxics regulatory programs
administered through State and local agencies. Elements such as
permitting, source testing, ambient monitoring, agency contacts,
acceptable ambient limits and guidelines, and program overviews
are all contained within the database. Information is collected
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on an annual basis by voluntary submittal from participating
agencies.
Since its introduction in 1984, NATICH has undergone
periodic modifications in an attempt to expand and meet the needs
of the user community. In the fall of 1989, a link was
established between NATICH and the Toxic Release Inventory System
(TRIS). A modification is in the planning stages to move the
database from the NCC's IBM mainframe onto the OAQPS TTN Bulletin
Board System for easier and wider accessibility.
STATE AIR OFFICE DATABASES
Emissions Standards Division (ESD) staff have been working
with STAPPA/ALAPCO to better characterize the toxics information
available in database form and hard copy within the State air
offices.
Most States have compiled pollutant information in some form
in response to State Implementation Plan (SIP) requirements.
Many States also have toxics information collection systems, as
well as State requirements for toxics programs in the air
offices. Most States find that although internally their system
is widely used (intra-State system), to down load or upload data
on an inter-State basis is nearly impossible (with the primary
exception to this being States within a transport region, and
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then usually under limited circumstances). Many States have
expressed a keen interest in a National database that each State
could down load State-specific data into, and upload multi-State
retrievals from. This capability is met by three main systems in
EPA: BLIS, AIRS, and NATICH.
Many States use the Aerometric Information Retrieval System
(AIRS) to input their information and perform calculations and
retrievals. When a converter (an interface between AIRS and the
State system) is used, the data can be input directly into the
State system and the converter then enters it into the
appropriate fields in AIRS. Data can also be retrieved from AIRS
into the State format with a converter.
Since many data sources are fed into AIRS/AFS, the system
becomes a repository of a vast amount of data. A great deal of
this will be useful for case-by-case MACT determinations and MACT
standards. This advantage is expected to become more visible as
the search for the 12% floor for a source category becomes a
common occurrence.
Some State data is not generally found in the State systems
because it is not needed for their current reporting
requirements. However, much of the information missing from the
database system can be found in the files documenting source
categories and processes of industry reports. States may wish to
enhance their current systems to hold such additional data fields
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and data elements from their participating industries.
OTHER SOURCES OF INFORMATION
TRADE JOURNALS
Caution should be taken when employing these sources,
especially in noting the method of emissions estimation, number
of tests which were used in developing estimates, and the
conditions under which tests were conducted. Other factors which
may affect the emissions estimates should also be identified, and
the effects of their differences quantified as accurately as
possible. Because results applicable to only one facility can
not be completely accurate for other facilities, this source of
information is not regarded as highly accurate.
This source of information may be somewhat biased as trade
journals are commonly published and funded by the industry
members of a trade association. However, these journals are
completely acceptable as long as the results used can be
substantiated.
TOXIC RELEASE INVENTORY SYSTEM (TRIS)
This is a source of data that was used to identify HAP
emitters. The TRIS database contains emissions data reported by
individual industrial facilities as required under Section 313 of
the Emergency Planning and Community Right-to-Know Act of 1988.
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Emissions data in TRIS are reported on a plant wide basis.
Standard Industrial Classification (SIC) Codes are reported in
TRIS but the entries are usually not specific enough to identify
categories of sources. The TRIS database is reportedly capable
of identifying plants emitting pollutants listed in Section
112(b).
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List of References
Air Pollution Training Institute (APTI). December 1983.
Overview of PSD Regulations. EPA 450/2-82-008.
Air Pollution Treaining Institute (APTI). June 1983. Air
Pollution Control Systems for Selected Industries.
EPA 450/2-82-006.
Environmental Protection Agency (EPA). May 1992. Facility
Pollution Prevention Guide. EPA, 600/R-92/088.
Environmental Protection Agency (EPA). February 1992.
Documentation for Developing the Initial Source Category
List. EPA, 450/3-91-030
Environmental Protection Agency (EPA). June 1991. Hazardous
Waste TSDF - Background Information for Proposed RCRA Air
Emission Standards. EPA, 450/3-89-023 (a) and (c).
Environmental Protection Agency (EPA). October, 1990. New Source
Review Workshop Manual. EPA, Research Triangle Park, NC
(Draft Document).
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Environmental Protection Agency (EPA), January 1990. OAOPS
Control Cost Manual. EPA, 450/3-90-006.
Environmental Protection Agency (EPA). September 1986. Control
Technologies for Hazardous Air Pollutants.
EPA, 625/6-86-014.
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Appendix A
The following detailed examples presented in this
manual are for illustrative purposes only. Numbers and values
presented in this Appendix do not necessarily reflect any known
cases and are not meant to establish any US EPA position
regarding MACT determinations for a particular MACT-affected
source. These examples are fictitious and are designed to
highlight many of the subtle aspects of the MACT determination
process. In many cases, the scenarios and available control
technologies have been grossly oversimplified to streamline the
presentation of the examples.
The proceeding examples assume that an owner or operator has
already determined that the major source will be constructed,
reconstructed or modified.
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Example l
Determining the
MACT-Affected Emission Unit
The owner or operator of a major source in the miscellaneous
metal parts source category is subject to a MACT determination
under Section 112(j). The following is a description of the
source and the operations at the facility:
A metal furniture manufacture produces military-
specification office furniture for use in military barracks. The
plant currently operates 2080 hr/yr and produces 12,000 units of
furniture annually. Estimated emissions from the major source are
100 tpy of HAPs.
Existing unit operations include:
1) wood processing
Raw wood and formica are glued together to form a
laminate. The glue is applied using an automatic application
system. Several laminates are then positioned in a press for
glue curing. Next, the boards undergo various woodworking
operations including, cutting, drilling, and routing.
Boards are either transferred to assembly or directly
packaged and shipped. Tetrachloroethylene is a component of
the glue. Glue stations are vented to emission stacks on
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the ceiling. The stacks are currently uncontrolled.
The glue is stored in 50 gallon drums. Glue is
transferred to the application equipment through a pumping
mechanism.
Estimated yearly emissions of HAP from this operation
is 0.50 tpy.
2) Metal Processing
Metal stock is cleaned by immersion in a toluene dip tank.
A toluene, grease, and dirt sludge is produced which is pumped
from the bottom of the tank for disposal. After cleaning the
metal undergoes various metalworking operations including
cutting, punching, folding and welding. Pieces are partially
assembled, then transferred to one of two paint coating
operations. The dip tank is currently controlled with a
condensing unit and a freeboard ratio of 0.75. Yearly controlled
emissions are estimated at 19 tons/yr. Uncontrolled emissions
are estimated at 55 tpy.
3) Cleaning operations:
The spray coating operations begins with a five-stage
cleaning. The first stage is an alkaline-wash tank. Next, parts
are sprayed with an iron phosphate solution. The fourth stage is
a rinse tank. Finally, parts are sprayed with a rust preventive.
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After cleaning, the parts are conveyed to a dry-off oven and then
the paint coating line. No HAP emissions occur during this part
of the operation.
4) Painting operations:
There are currently four spray booths in the paint
coating operation, and one dip-spray tank. Large metal
parts are coated using the spray booths. A one color coating
is applied at a coating depth of 1 ml. Two of the booths
are equipped with continuously recirculating water curtains
to entrap paint overspray. Entrapped paint solids and
wastewater are dumped to a holding tank periodically. Air
filters are used in the two remaining spray booths. The Air
filters are periodically replaced. The used filters are
placed in storage drums for later disposal.
All spray booths are equipped with hand-held spray
guns. Transfer efficiency is estimated at 45% for both
types of booths. The paint is a high solvent paint
containing xylene and toluene with an estimated 35% solids
content and 65% solvent content. The spray guns are
periodically sparged and rinsed with acetone to prevent
clogging. The acetone paint mixture is sent to storage
tanks for later disposal. Emissions from the booths are
currently vented to the roof with no control devise.
After painting parts are conveyed through a flash-off
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area to one of two dry-off ovens and then to assembly. Small
metal parts are dip-painted, allowed to air dry, and then
transferred to the assembly area.
Total annual HAP emissions from this area are estimated
at 55 tpy. Each spray booth contributes 8 tpy and each
drying oven 4 tpy. Estimated emissions from the dip-spray
tank are 15 tpy. No emission estimates are available for
the flash-off area.
From this description the following emission points are
indentified as potentially "affected emission points" by the
Section 112(j) MACT determination process:
glue storage drums
glue stations (stack emissions)
—application equipment
—curing presses
dip tank*
toluene storage tanks*
toluene/sludge waste storage tanks*
spray booths (stack emissions)
— feed and waste lines
— application equipment
spray dip-tank
flash-off area (large parts)
drying area (small parts)
paint storage tanks
solvent storage vessels
paint sludge storage tanks
drying ovens (stack emissions)
Air filter storage drums
* These unit would be eliminated from any MACT-affected
emission unit because the emission points would be part of
the degreasing source category, not the miscellaneous metal
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parts surface coating source category.
Possible MACT-affected emission unit scenarios:
Scenario #1 There would be five MACT-affected emission units:
Wood processing
Spray coating operations
Storage tanks
Equipment leaks
storage drums
The above scenario could make sense if a MACT floor could be
identified or control technologies could be applied to the
emission units. In wood processing the emissions are vented to a
stack on the roof. These emissions could be controlled with a
variety of add-on control devices. The source could also
consider switching to a glue that has a lower concentration of a
HAP or does not contain any HAPs.
In the spray operations, the source could switch to a low
solvent paint or water-based paint. This control option would
need to be weighed against controlling the individual emission
points. Other control options to consider would be an add-on
control devise to control the stack emissions from the spray
booth and oven, increasing the transfer efficiency of the spray
application equipment, and controlling the drying, flash-off
areas, and the dip-spray tank with separate control technologies.
Controlling the storage tanks as one emission unit may allow
flexibility in meeting MACT. Some tanks could remain under
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controlled while others could be over-controlled. This option
would need to be weighed against the cost effectiveness and
emission reductions of applying controls to all of the storage
tanks. The storage drums could be placed in a contained area and
the emissions vented to one control devise.
Scenario #2
Stack emissions (spray booths, glue stations, drying ovens)
storage tanks and drums
equipment leaks
dip-spray tank
In this scenario, the stack emissions from the spray booths,
glue stations and drying oven could all be vented to a single
control devise. This option would need to be weighed against the
emission reductions that could be obtained by applying pollution
prevention strategies to the individual operations. If the
storage tanks and drums are stored in a common location, such
that the emissions from the area could be vented to a control
devise, this emission point aggregation could make sense. The
emission reduction would need to be weighed against controlling
the emission points separately. If greater emission reductions
could be obtained by controlling these points separately, this
aggregation of points may not be acceptable.
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Scenario #3
each storage tank
each spray booth
stack emissions from glue stations and drying oven
equipment leaks
each storage tank
each storage drum
dip-spray tank
This scenario would generally be acceptable unless a
pollution prevention method could be applied to one of the
processes that could obtain a greater degree of emission
reductions then point-by-point compliance.
Scenario #4
All emission points
This scenario would generally be unacceptable because
equipment leak emissions should not be included in a source
category wide emission unit.
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June 1993
Scenario #5
equipment leaks
remaining emission points
This aggregation of emission units could be acceptable if
emissions information were available on HAP emissions or control
technologies from the source category as a whole, or if the
nature of the industry demanded a large degree of flexibility in
the application of MACT. A justification for this conglomeration
would be necessary.
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Example 2
Using control Efficiency Ratings to Determine the MACT Floor
A MACT determination is to be conducted on a quenching
process at a coke-by product plant. Hazardous emissions can be
released when the hot coke in the quench car is sprayed with
water to decrease the coke's temperature. Phenol and naphthalene
emissions can occur in the gaseous state. Other pollutants can
sorb to particulate matter and be collectively released. The
owner or operator will need to conduct a MACT analysis to
recommend a MACT emission limitation and specify a control
technology to comply with the MACT floor for existing major
sources. The owner or operator will begin with the Tier I
analysis.
Steps 1) Identify the MACT-affected emission unit(s)
MACT-affected source: quenching tower and coke car
# of existing sources: 36
The equipment used in this production process include the
quenching tower, the coke car, water delivery system, and water
storage system. After consulting with the permitting agency, it
is decided that emission points from the quenching tower and coke
car should be considered one MACT-affected emission unit, and the
water delivery system and water storage system as another
affected emission unit. The example will be continued for only
the quench tower/coke car emission unit.
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Proposal
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Step 2) Make a MACT floor Finding
Technology
1) Use clean water
to quench coke
with baffles at the top
of the quench tower
of plants using
10
%efficiencv
not
quantifiable
2) Use covered quenched car.
Cool outside of car.
Water does not impact
coke. Place car on cooling
rack after quenching for
additional heat
dissipation.
almost 100%
3) Wet scrubber, connected
to fixed duct system
4) Wet scrubber, mobile unit
attached to coke quench car
5) Dry quenching with inert
gases. Heat transported to
waste-heat boiler
10
14
80-90%
80-90%
99-100%
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Proposal
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The owner or operator has decided to use the control
efficiency ratings to determine the MACT floor. There are a
total of 36 existing sources. The MACT floor would be equivalent
to the arithmetic mean of the control efficiency ratings for the
best five sources. If a specific control efficiency rating is
not available for the best performing five sources, a median or
mode could be used to calculate the MACT floor. Using the
information provided, the median of the best performing 12% of
sources would be equal to 80-90% or control technology 3 or 4.
The mode would be technology number 4.
Step 4 Select a control technology as the MACT
Technologies 2, 3, 4, or 5 could be chosen as MACT. Number
1 could also be consider because its control efficiency is not
quantifiable. If the owner wished to consider technology 1, a
more detailed analysis would be required to prove that the
technology could obtain an equal or greater amount of emission
reductions. In this case, the efficiency of technology 1 will
vary by the concentration of hazardous constituents. Using clean
water could result in a less toxic release when the concentration
of toxins in the hot coke are less, but increased emissions could
result with increased concentrations. The other proposed
technologies would operate at a relatively constant efficiency
rate, regardless of the pollutant concentration. Therefore,
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technology number 1 would be considered inferior and should be
eliminated as a potential candidate.
The owner or operator should consult with the reviewing
agency to determine whether a costs, non air quality health and
environmental impacts and energy requirements analysis is
required for the available control technologies. If not, the
owner or operator could select any of these control technologies.
If an analysis is required, the control technology achieving a
maximum degree of reduction in emissions of the HAPs should be
selected based on the costs, non-air quality environmental and
health impacts and energy requirements analysis. After selecting
the technology the owner or operator would proceed to Tier III of
the analysis. In Tier III, the appropriate operation conditions
and design specification would be prescribed in lieu of a
specific MACT emission limitation.
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Example 2
When the MACT floor is Determined
using Emission Reduction Ratios
Description of Source
A surface coating operation treats a product with its
existing equipment consisting of a dip-tank priming stage
followed by a two-step spray application and bake-on enamel
finish coat. The product is a specialized electronics component
(resistor) with strict resistance property specifications that
restrict the types of coatings that may be employed.
Step 1) Identify the MACT-affected emission unit(s)
MACT-affected emission units - 1. dip-tank
2. feed and waste lines in
prime coating operation
3. spray coat booth, spray
coat application equipment
4. drying oven
5. storage tank in prime
coating operation
6. storage tank in finish
coating line
There are two process units within this source category: the
prime coating line and the finish coating line. Equipment within
the prime coating line that have affected emission points are a
dip-tank, storage containers, feed line to supply new coating
into the dip-tank, a waste line to drain the dip-tank. Because
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the feed line and waste lines have equipment leak emissions,
these emission points should be combined to form a MACT-affected
emission unit. The owner or operator will consider the dip-tank
and each storage container a separate affected emission unit.
The three MACT-affected emission units in this process unit are
the dip-tank, the storage container, and the feed and waste
lines.
The finish coating line consists of two spray booths, spray
application equipment, paint supply system, a storage container,
and a drying oven. After consulting with the permitting agency,
the owner or operator combines affected emission points to form
the following MACT-affected emission units: the spray
application equipment and spray booths; the paint supply system,
the storage container, and the drying oven. For simplicity of
this example, the MACT analysis will be continued for only the
spray application equipment and spray booths.
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Step 2) Make a MACT floor finding
Steps A and B: Computing the Uncontrolled Emissions and
Controlled Emissions
Overview Analysis of emissions information for similar emission
units within the source category:
Technology * of sources using
1) water-based coat 2
2) low-VOC solvent/high 4
solids coat
3) electrostatic spray 7
application to enhance
transfer efficiency
4) low voc solvent/high solids 8
coating with electrostatic
spray application
5) powder coat paint with 1
electrostatic spray
application
6) high-voc solvent coating 8
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Proposal
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Detailed analysis
Source
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
Technology
#
6
3
2
3
3
6
6
3
2
2
6
6
6
3
2
3
4
5
4
3
4
4
Uncontrolled
emissions
(tons/yr)
10
26
48
86
98
26
35
78
69
15
11
12
23
85
141
25
159
126
35
25
68
46
Controlled
emissions
(tons/yr)
10
14
22
56
55
22
34
55
25
11
11
12
22
52
89
20
100
11
14
16
22
10
Emission
reduction
ratio
0
.46
.54
.35
.44
.15
.03
.29
.64
.27
0
0
.04
.39
.39
.20
.37
.91
.6
.36
.70
.78
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Proposal
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Source
23
24
26
27
28
29
30
Technology
#
1
L_6
4
4
4
4
6
1
Uncontrolled
emissions
(tons/yr)
95
96
64
98
168
196
186
255
' > !=
Controlled
emissions
(tons/yr)
10
16
25
31
45
63
186
26
Emission
Reduction
Ratio
.89
.83
.61
.68
.73
.68
0
.90
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Proposal
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Step C Computing the Emission Reduction Ratio for the
MACT- Affected Emission Unit
Because there are 30 sources, the MACT floor should be based
on the arithmetic mean of the emission reduction ratios achieved
by the best 12% of existing emission units. Twelve percent of 30
emission units is equal to 3.5 sources. The owner or operator
should round up all fractions to the next largest number. The
MACT floor would be equal to the arithmetic mean of the emission
reductions obtained by the best 4 sources in the source category.
Reviewing the data above the MACT floor would be equal to an
emission reduction ratio of 0.88 ([0.91 + 0.90 + 0.89 + 0.83]/4)
or the emission reductions that can be achieved when control
technologies 1 or 5 are used. In this example, the nature of the
product requires a specific type of coating. Technology 1 and 5
are inappropriate for application to this MACT-affected emission
unit. The owner or operator would continue with the analysis to
identify other technologies that can meet a 0.88 emission
reduction ratio.
Step D Determine a MACT emission limitation (MEL)
The owner or operator of the MACT-affected emission unit
needs to calculate an uncontrolled emission rate for the MACT-
af fected emission unit. Because current design specifications
for existing emission unit cause a larger uncontrolled emission
rate than any other designs used in the past 5 years, the current
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Proposal
June 1993
operational designs will be used to determine the uncontrolled
emissions. With the existing coating material, the MACT-affected
emission unit has an uncontrolled emission level of 125 tons/yr
total HAPs. The MEL for this emission unit would be
MEL = 125 tons/yr * (1 - 0.88)
= 15 tons/yr
Step 4 Select a control technology to meet the MACT Emission
Limitation.
In this case, the owner or operator must select a control
technology that allows the source to meet the MACT emission
limitation. Because the owner and operator can not use any of
the identified control technologies to meet the MACT floor,
control technologies to control similar emission points will be
considered. In this example, the similar emission points have
operational losses. Review of control technologies to control
operational losses identifies add-on control devises such as a
carbon absorber, a thermal or catalytic incinerator, or a
condenser. The owner or operator should conduct a costs, non-air
quality health and environmental impacts and energy requirements
analysis on the available control technologies.
The major source already has a catalytic incinerator on
site. The emissions from the spray application equipment and
spray booth could be channeled to the incinerator. This would
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Proposal
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require the installation of a venting system including a pump
mechanism. It would also require an increased volumetric flow
rate to the incinerator and increase auxiliary fuel requirements.
The incinerator had been operating at a 90% efficiency. With an
increased volumetric flow rate, the efficiency is projected to
drop to 87% efficiency. The owner and operator must obtain an
additional 1% emission reductions. Possible control technologies
include increasing the operating temperature of the incinerator,
or adding electrostatic application to the spray process to
enhance transfer efficiency. Limiting the hours of operation at
the MACT-affected emission unit could be considered if the
reduced production were part of an overall source reduction
program.
Use of the specialized coating in this operation will
increase the concentration of hazardous pollutants in the water
used for the water curtain. The proposed control technology does
not affect the concentration of pollutants in the wastewater.
This could be considered a negative environmental impact and may
be reason to consider another control technology to meet the MACT
emission limitation. In this instance, the owner or operator
will not violate the NPDES permit, so the MACT candidate will not
be eliminated from consideration.
The owner or operator uses this step to demonstrate that
despite the increase in volumetric flow rate and the auxiliary
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June 1993
fuel requirement, a significant increase in CO2 emissions does
not occur. The owner or operator concludes that the impacts
associated with use of this technology are reasonable.
After reviewing the technologies the owner or operator
selects the incinerator with a limit on the hours of operation.
The owner or operator proposes to start a training program for
spray booth operators to decrease the error and product rejection
rate. By doing this, the owner or operator can reduce the hours
of operation and still meet customer demands for the product.
This option was chosen over the other two because increasing the
incinerator's operating temperature would require additional
auxiliary fuel input, and enhancing the transfer efficiency with
electrostatic application would be cost prohibitive. The owner
or operator would document that use of the selected control
technologies can reduce emissions to the required level.
The owner or operator would move to Tier III of the analysis
and document the MACT emission limitation, and suggest
appropriate conditions to assure that this MACT emission
limitation is federally enforceable.
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Example 3
When the MACT floor is Equal to "No Control"
A commercial treatment storage and disposal facility
receives off-site wastes from various pesticide manufacturers. A
solvent/aqueous/pesticide mixed waste is passed through a
distillation column where the organic solvents are vaporized and
then condensed into a distillate receiver. The solvent is
transferred using tank cars to a tank farm that is located at
another portion of the plant. The low-grade solvent is then sold
to industrial users. The pesticide-laden wastewater is then
passed through a series of carbon adsorbed where the majority of
pesticide is removed from the water. The water is then
discharged to a Publically Owned Treatment Works (POTW). The
carbon adsorbers are periodically steam stripped to regenerate
the carbon.
Step 1) Identify the MACT-affected emission unit(s)
MACT-affected emission units: 1) each storage tank
2) the distillation column,
condenser, and distillate
receiver
3) the three carbon absorber
4) pumps, feed lines and
transfer lines
5) loading racks
The two process units that contain emission points affected
by this modification are the recycling process, and the tank
farm. The equipment and apparatus associated with the affected
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Proposal
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emission points are pumps, feed lines, a distillation column, a
condenser, a distillate receiving tank, three carbon absorber and
transfer lines, and a loading rack, and storage tanks. After
consulting with the permitting agency, the owner or operator will
consider the three carbon absorbers and the associated emission
points as one emission unit because a single control technology
could be practically design to cover all three affected emission
points. The owner or operator will also group the distillation
column, distillate receiver and condenser into one MACT-affected
emission unit. The feed lines, pumps, and transfer lines would
have equipment leak emission losses and would be another affected
emission unit. The owner and operator has decided to consider
the emission points and equipment for the loading rack and tanks
as separate MACT-affected emission units. If all the tanks were
structurally similar in design one determination could be made
that would be applicable to all the tanks.
Step 2) Make a MACT floor finding
For simplicity of this example, the MACT analysis will only
be continued for a tank emission unit. All the storage tanks
will be structurally similar, so only one MACT determination will
be required. The manufacture has reviewed existing data bases
and determined that less than 12% of tanks in the source category
are controlled. Therefore the MACT floor is equal to "no
control". This is not automatically an acceptable "control"
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Proposal
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measure, so the owner or operator will move to Tier II of the
MACT analysis. In Tier II of the analysis control technologies
for similar emission points from outside the source category will
also be considered.
Tier II - Step 1 List All Available Control Technologies
The following technologies have been identified as possible
control technologies that can be applied to a storage tank to
control working and breathing emission losses:
Emission control
efficiency
1. fixed-roof 86-99
2. fixed-roof plus internal floating roof 97-99
3. fixed roof vented to a carbon canister 95-100
4. fixed-roof vented to a combustion devise 99-100
5. fixed-roof vented to carbon absorber 99-100
6. pressure tank 95-99
Step 2 Eliminate Technically Infeasible Control Technologies
All of the available control technologies are technically
feasible.
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Proposal
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Step 4 Conduct a Non-air Quality Health, Environmental, Economic
and Energy Impacts Analysis
The following charts illustrates a non-air quality health,
environmental, cost and energy impacts analyses of each control
option.
Control Option
1 fixed roof
2 fixed roof +
internal roof
3 pressure tank
4 cover and
vented to
carbon canister
5 cover and vent
to combustion
devise
cover and vent to
carbon absorber
Secondary Air Impacts
none
none
none
emission if
carbon regenerated
increased CO, NOx,
SOx, and particulate
emissions
emissions when
carbon regenerated
Resource Demands
none
none
none
disposal of
container, solvents
for regeneration
fuel source,
disposal of ash
disposal of spent
carbon, solvents for
regeneration
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Proposal
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Control
Technology
1
2
3
4
5
6
Average
Control
Efficiency
(%)
93
98
98
98
100
100
Emission
Reductions
(Mg/yr)
25
26
26
26
27
27
Capital
Investment
($)
3790
7330
4840
5270
5790
5270
Annual
Cost
($)
760
1870
3560
1020
1080
4230
Average
Cost
Effectiveness
($/Mg)
30
72
137
39
40
157
Incremental
Cost
Effectiveness
($/Mg)
1110
2800
260
60
3210
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Proposal
June 1993
The manufacturer will chose option 4 as the MACT candidate.
Control technology 1 was eliminated because it had the lowest
control efficiency and the cost, environmental, and energy
considerations did not preclude the use of a control technology
that obtains a greater reduction in emissions. Control
technologies 2 and 3 were eliminated because control technology 4
is equally efficient in reducing emissions, but has a much lower
cost than technologies 2 and 3. Technology 5 could have been a
suitable candidate, but the manufacturer eliminated it due to its
secondary air and energy impacts. Technology 6 has been
eliminated because the capital investment and annual costs are
high and there are secondary air and other impacts that are not
outweighed by the emission reductions that would be obtained.
The owner or operator will progress to Tier III of the
analysis and determine the degree of reduction in emissions of
the HAPs that can be obtained if the storage tanks are covered
and vented to a carbon canister.
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Appendix B
Forum of Anticipated Questions
1. When computing the number of sources in the "best 12% or
best 6% of similar sources in the source category" should the
number of sources be rounded to the nearest or next largest whole
number?
For example if there are forty-five similar sources in the source
category would the "best 12%" include 5 or 6 sources.
The number should be rounded to the next largest number. In
the example the "best 12%" would include 6 sources.
2. How many decimal points should be in the emission reduction
ratio, and the manufacturer's efficiency rating?
The emission reduction ratio should be carried to two
decimal places. The efficiency rating should be rounded to the
nearest whole number.
3. Should the emission limitation(s) be based on overall HAP
emissions or emissions of an individual HAP?
The emission limitation may be based on overall HAP
emissions or a specific emission limitation may be specified for
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Proposal
June 1993
an individual HAP. A specific emission limitation may be
established if health risks warrant placing an individual
emission limitation, or if an individual emission limitation is
needed to make the overall HAP emission limitation federally
enforceable.
4. If a major source already complies with a case-by-case MACT
determination under Section 112(j) and it later proposes to
constructed a new source, and emissions also increase from
existing equipment or apparatus, what type of determination, if
any is done for the existing equipment?
If the emission increases from the new source are not
greater than de minimis as defined by 40 CFR Part 63,
Subpart B, the owner or operator would be require to meet a
new source level of control, but would not be required to
apply for any preconstruction review, unless such a review
is required by the individual permitting agency. If the
emissions increases are above de minimis, the construction
may constitute a modification, construction or
reconstruction of a major source as defined in 40 CFR Part
63, Subpart B. If this is the case, a notification of the
construction or a preconstruction review may be required.
5. A non-major source undergoes a construction, reconstruction
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Proposal
June 1993
or modification and increases emissions above a de minimis
amount. This emission increase reclassifies the source as a
major source for which the source category is subject to a
Section 112(j) determination. What type of MACT determination
would be required for the source.
The entire source category at the major source would be
subject to a Section 112(j) determination and would need to
immediately apply for a Title V permit application
reflecting a MACT emission limitation on all affected
emission points within the source category. A permitting
agency may also require that the owner or operator obtain a
Notice of MACT Approval before the construction or
reconstruction. Any emission points subject to the
modification provisions of Section 112(g) would require the
affected emission units to obtain a Notice of MACT Approval
through the Section 112(g) process before beginning
construction of the modification.
6. Must MACT always be an add-on control devise?
No. MACT is a control technology which can include add-on
controls, work practices, pollution prevention methods, etc
7. A major source has agreed to participate in the volunteer
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Proposal
June 1993
emission reductions program pursuant to Section 112 (i) (5) of the
Act. Through this program, an owner or operator of a major
source can obtain a compliance extension for a future MACT
standard, if a 90% reduction in emissions is achieved before
promulgation of that relevant emission standard. Is this source
subject to a Section 112 (j) MACT determination.
In order to avoid a case-by-case MACT determination under
Section 112 (j), the source must have obtained the required
level of emission reductions by the promulgation deadline
for the relevant source category. If the source has met the
required level of reduction, it is still required to apply
for a Title V permit to incorporate the alternate emission
limitation into the permit unless such limit is already in a
Title V permit. If the alternate emission limitation has
not been achieved by the promulgation deadline a case-by-
case MACT determination would be required under Section
8. In the course of conducting a MACT analysis for a Section
112 (j) Title V permit application, the owner or operator
discovers that the MACT floor is equal to 97% control. Could the
owner or operator enter the early reductions program and only
obtain 90% control?
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Proposal
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If the promulgation deadline for a source category has been
missed, the source is no longer eligible for the early
reductions program.
9. If a State develops a general permit applicable to certain
emission units in a source category, is an owner or operator
required to apply for the general permit rather than a specific
Title V permit?
No. Using available information, the owner or operator
could prepare an application for a specific Title V permit
rather than apply for the general permit.
10. If a State has conducted a MACT analysis which is provided
to the owner or operator, is the owner or operator required to
use the results of this MACT analysis?
Unless, the State has passed a specific State law using the
MACT analysis, an owner or operator is not required to rely on
the State MACT analysis. However, the owner or operator is
required to prepare an application using all available
information. This would require the source to use the
information the State used to conduct the MACT analysis.
Additional information could be added to the application, if it
is publically available, accurate and reliable.
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DEFINITIONS
Act - the Clean Air Act as amended in 1990 (42 U.S.C. 7401 et seq..
as amended by Pub. L. 101-104 Stat. 2399).
Administrator - the United States Environmental Protection Agency
or his or her authorized representative (e.g a State that has been
delegated the authority to implement the provisions of this part.)
Affected emission point - an emission point identified as being
part of a modification, construction or reconstruction and
requiring a MACT determination.
Alternative test method - any method of sampling and analyzing for
an air pollutant that is not a test method in 40 CFR Part 63 and
that has been demonstrated to the Administrator's satisfaction,
using Method 301 in Appendix A of Part 63, to produce results
adequate for the Administrator's determination that it may be used
in place of a test method specified in that part.
Approved permit program - a State permit program approved by the
Administrator as meeting the requirements of 40 CFR Part 70, or a
federal permit program established under 40 CFR Part 71.
Controlled emissions - the sum of all hazardous air emissions from
all emission points given the maximum design capacity currently in
use by the emission unit taking into consideration the application
of all existing control technologies and federally enforceable
limits.
Control technology - measures, processes method, systems, and
techniques to limit the emission of hazardous air pollutants
including, but not limited to, measures which
(1) reduce the volume of, or eliminate emissions of, such
pollutants through process changes, substitution or materials
or other modifications,
(2) enclose systems or processes to eliminate emissions,
(3) collect, capture or treat such pollutants when released
from a process, stack, storage or fugitive emissions point,
(4) are design, equipment work practice, operational standards
(including requirements for operator training or
certification) as provided in subsection (h), or
(5) are a combination of above.
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June 1993
Commenced - with respect to construction, reconstruction or
modification of a stationary source, that an owner or operator has
undertaken a continuous program of construction, reconstruction or
modification or that an owner or operator has entered into a
contractual obligation to undertake and complete, within a
reasonable time, a continuous program of construction,
reconstruction, or modification.
Compliance date - the date a MACT-affected emission unit is
required to be operating and meeting all the requirements of the
Notice of MACT Approval. For new sources this date is upon start-
up. For existing sources this date should be as soon as
practicable, but no later than 3 years from the effective date, or
as otherwise specified by a relevant emission standard.
Construct - to fabricate (on site), erect, or install a stationary
source which is or may be subject to a standard, limitation,
prohibition, or other federally enforceable requirement established
by the Administrator (or a State within approved permit program)
pursuant to Section 112 of the Act.
Continuous emission monitoring system (GEMS) - the total equipment,
meeting the data acquisition and availability requirements of this
part, used to sample, condition (if applicable), analyze, and
provide a permanent record of emissions.
Continuous monitoring system (CMS) - a continuous emission
monitoring system or a continuous parameter monitoring system.
Effective date - the date a Notice of MACT Approval is signed and
issued by a permitting agency, or the date specified in a
promulgated emission standard.
Emission Unit - one emission point or the collection of emission
points within a major source requiring a MACT determination.
An emission unit can be defined (by the permitting authority) as
any of the following:
(1) An emitting point that can be individually
controlled, e.g. a boiler, a spray booth, etc.
(2) The smallest grouping of emission points, that, when
collected together, can be commonly controlled by a single control
device or work practice.
(3) A grouping of emission points, that, when collected
together, can be commonly controlled by a single control device or
work practice.
(4) A grouping of emission points that are functionally
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related. Equipment is functionally related if the operation or
action for which the equipment was specifically designed could not
occur without being connected with or relying on the operation of
another piece of equipment.
(5) A grouping of emission points that, when collected
together, comprise a building, structure, facility, or
installation.
Existing Source - a source that is not constructed or
reconstructed.
Federally enforceable - all limitations and conditions which are
enforceable by the Administrator, including those requirements
established by State or Local agencies who have received delegation
to impose such limitations through an approved Part 70 permit
program or through Section 112(1) of the Act. Requirements
developed pursuant to Part 60 and Part 61 of this chapter and
requirements within any applicable State Implementation Plan are
also considered federally enforceable. To be federally
enforceable, the limits and conditions must undergo public review
and be reported to the EPA. Emission limits that are considered
federally enforceable include limits on the allowable capacity of
the equipment; requirements for the installation, operation and
maintenance of pollution control technologies; limits on hours of
operation; and restrictions on amounts of materials combusted,
stored or produced. To be federally enforceable, restrictions on
operation, production or emissions must reflect the shortest
practicable time period (in no event for a period in excess of 30
days.) General limitations such as yearly limits (e.g. tons per
year) are not considered federally enforceable. The use of hourly,
daily, weekly, or monthly rolling averages are acceptable. Any
federally enforceable limitations or conditions must be practically
enforceable and ensure adequate testing, monitoring, and
recordkeeping to demonstrate compliance with the limitations and
conditions.
Fugitive emissions - emissions from a stationary source that could
not reasonably pass through a stack, chimney , vent or other
functionally equivalent opening.
Hazardous Air Pollutant (HAP) - any air pollutant listed in Subpart
C of 40 CFR Part 63 pursuant to Section 112(b) of the Act. When
there is a discrepancy between the hazardous air pollutant list in
Section 112 (b) and the list in Subpart C, the list in Subpart C
shall supersede the list in Section 112(b).
Maximum achievable control technology fMACT) - a control technology
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that achieves a maximum degree of reduction in emissions of the
hazardous air pollutants with consideration to the costs of
achieving such emission reductions, and the non air quality health
and environmental impacts and energy requirements.
MACT-affected emission unit - an emission unit or source requiring
a MACT determination.
MACT analysis - the process an owner/operator conducts to define
the MACT floor, recommend a MACT emission limitation, and select
the MACT.
MACT determination - a process conducted by the Administrator to
evaluate a major source's ability to comply with the requirements
of 40 CFR Part 63, Subpart B.
MACT emission limitation (MEL) - the maximum achievable control
technology emission limitation for the hazardous air pollutants
listed under Section 112(b) of the Act that the Administrator (or
a State with an approved permit program) determines through a
promulgated emission standard or on a case-by-case basis to be the
maximum degree of reduction in emissions of the HAPs with
consideration to the costs of achieving such emission reductions
and the non air quality health and environmental impacts and energy
requirements.
If the Administrator or reviewing agency determines that it is
inappropriate to prescribe a numerical or efficiency based MACT
emission limitation a specific design, equipment, work practice,
operational standard, or combination thereof, may be prescribed
instead. Such standard shall, to the degree possible, set forth
the emissions reduction achievable by implementation of such
design, equipment, work practice, or operation, and shall provide
for compliance by means which achieve equivalent results.
MACT floor - for new sources or constructed or reconstructed major
sources: a level of hazardous air pollutant emission control that
is achieved in practice by the best controlled similar source as
determined by the Administrator.
For a existing sources or a modification to a major source the
MACT floor is:
(a) the average emission limitation achieved by the best
performing 12 percent of existing sources (for which the
Administrator has emission information), excluding those
sources that have, within 18 months before the emission
standard is proposed or within 30 months before such
standard is promulgated, whichever is later, first
achieved a level of emission rate or emission reductions
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which compiles, or would comply if the source is not
subject to such standard, with the lowest achievable
emission rate (as defined by Section 171 of the Act)
applicable to the source category and prevailing at the
time, in the category or subcategory for categories and
subcategories with 30 or more sources; or,
(b) The average emission limitation achieved by the best
performing 5 existing sources for sources with less than
30 sources in the category or subcategory.
Ma-ior source - any stationary source or group of stationary sources
located within a contiguous area and under common control that
emits or has the potential to emit considering controls, in the
aggregate, 10 tons per year or more of any hazardous air pollutant
or 25 tons per year or more of any combination of hazardous air
pollutants, unless the Administrator establishes a lesser quantity
as codified in Subpart C of 40 CFR Part 63, or in the case of
radionuclides, different criteria from those specified in this
sentence.
Notice of MACT Approval - a document issued by a reviewing agency
containing all federally enforceable conditions necessary to
enforce the application of, and operation of MACT such that the
MACT emission limitation is met.
Owner or operator - any person who owns, leases, operates,
controls, or supervises a stationary source.
Part 70 permit - any permit issued, renewed, or revised pursuant to
40 CFR Part 70.
Part 71 permit - any permit issued , renewed, or revised pursuant
to Part 71 of this chapter.
Permit program - a comprehensive State or Federal operating permit
system established pursuant to regulations codified in 40 CFR Part
70 or Part 71.
Permit revision - any permit modification or administrative permit
amendment to a Part 70 or Part 71 permit as defined in those parts.
Promulgation deadline - for each source category the date by which
EPA is required to establish emission standards for the source
category in accordance with Section 112(c) of the Act. These dates
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are published in a regulatory schedule in the Federal Register.
Potential to emit - the maximum capacity of a stationary source to
emit a pollutant under its physical and operational design. Any
physical or operational limitation of the capacity of the
stationary source to emit a pollutant, including air pollution
control equipment and restrictions on hour of operation or on the
type or amount of material combusted, stored, or processed, shall
be treated as part of its design if the limitation or the effect it
would have on emissions is federally enforceable.
Project - all activities associated with construction,
reconstruction, or modification of a source including design,
fabrication, erection, installation and start-up.
Reconstruction - the replacement of components of an existing major
source to such an extent that (1) the fixed capital cost of the new
components exceeds 50 percent of the fixed capital cost that would
be required to construct a comparable entirely new source, and (2)
it is technologically and economically feasible for the
reconstructed source to meet the Section 112(d) emission
standard(s), alternative emission limitation(s), or equivalent
emission limitation(s) established by the Administrator ( or a
State with an approved permit program) pursuant to Section 112 of
Act. Upon reconstruction, an affected source is subject to Section
112(d) standards for new sources, including compliance dates,
irrespective of any change in emissions of hazardous air pollutants
from that source.
Relevant standard - (1) an emission standard, (2) an alternative
emission standard, (3) an alternative emission limitation, (4) an
equivalent emission limitation that applies to a stationary source
regulated by such standard or limitation. A relevant standard may
include or consist of a design, equipment work practice, or
operational requirements or other measures, process, method, system
or technique (including prohibition of emissions) that the
Administrator (or a State with an approved permit program)
determines is achievable for a constructed or reconstructed major
source, new or existing source to which such standard or limitation
applies. Every relevant standard established pursuant to Section
112 of the Act includes Subpart A of this part and all applicable
appendices of Parts 51, 60, 61, and 63 of Chapter 40 of the code of
federal regulations that are reference in that standard.
Similar emission unit - two or more sources or emission units that
have similar emission types and can be controlled using the same
type of control technology.
Similar emission type - See Section 2.4 of Chapter 2.
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Source - an emission unit, or as otherwise specified in an
applicable 40 CFR Part 63 emission standard.
Start-up - beginning operation of a source or emission unit.
State - all non-federal permitting authorities, including local
agencies, interstate associations, and State-wide programs, that
have delegated authority to implement (1) the provisions of 40 CFR
Part 63; and/or (2) the permit program established under Part 70 of
this chapter. State shall have its conventional meaning where
clear from the context.
Stationary source - any building, structure, facility or
installation that emits or may emit any air pollutant. For the
purposes of 40 CFR Part 63, stationary sources are listed in
categories pursuant to Section 112(c) of the ACT and published in
the Federal Register. (See Appendix D)
Uncontrolled emissions - the annual sum of hazardous air pollutant
emissions that could be emitted from all emission points at a
source in the absence of control technologies given the maximum
design capacity used by the source within the past five year period
proceeding the date of the proposed construction, reconstruction or
modification.
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Appendix D
Initial List of Categories of Major and Area
Sources of Hazardous Air Pollutants
Fuel Combustion
Category Name
Engine Test Facilities
Industrial Boilersb
Institutional/Commercial Boilers"
Process Heaters
Stationary Internal Combustion Engines*
Non-Ferrous Metals Processing
Category Name
Primary Aluminum Production
Secondary Aluminum Production
Primary Cooper Smelting
Primary Lead Smelting
Secondary Lead Smelting
Lead Acid Battery Manufacturing
Primary Magnesium Refining
Ferrous Metals Processing
Category Name
Coke By-Product Plants
Coke Ovens: Charging, Top Side, and Door Leaks
Coke Ovens: Pushing, Quencing, and Battery Stacks
Ferroalloys Production
Integrated Iron and Steel Manufacturing
Non-Stainless Steel Manufacturing - Electric Arc
Furnace (EAF) Operation
Stainless Steel Manufacturing-Electric Arc
Furnace (EAF) Operation
Iron Foundries
Steel Foundries
Steel Pickling-HCI Process
Mineral Products Processing
Category Name
Alumina Processing
Asphalt/Coal Tar Application-Metal Pipes
Asphalt Concrete Manufacturing
Asphalt Processing
Asphalt Roofing Manufacturing
Chromium Refractories Production
Clay Products Manufacturing
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Lime Manufacturing
Mineral Wood Production
Portland Cement Manufacturing
Taconite Iron Ore Processing
Wool Fiberglass Manufacturing
Petroleum and Natural Gas Production and Refining
Category Name
Oil and Natural Gas Production
Petroleum Refineries-Catalytic Cracking
(Fluid and other) Units, Catalytic
Reforming Units, and Sulfur Plant Units
Petroleum Refineries-Other Sources
Not Distinctly Listed
Liquids Distribution
Category Name
Gasoline Distribution (Stage 1)
Organic Liquids Distribution (Non-Gasoline)
Surface Coating Processes
Category Name
Aerospace Industries
Auto and Light Duty Truck (Surface Coating)
Flat Woods Paneling (Surface Coating)
Large Appliances (Surface Coating)
Magnetic Tapes (Surface Coating)
Manufacture of Paints Coatings, and Adhesives
Metal Can (Surface Coating)
Metal Coil (Surface Coating)
Metal Furniture (Surface Coating)
Miscellaneous Metal Parts and Products
(Surface Coating)
Paper and Other Webs (Surface Coating)
Plastic Parts and Products (Surface Coating)
Printing Coating, and Dyeing of Fabrics
Printing/Publishing (Surface Coating)
Shipbuilding and Ship Repair (Surface Coating)
Wood Furniture (Surface Coating)
Waste Treatment and Disposal
Category Name
Hazardous Waste Incineration
Municipal Landfills
Sewage Sludge Incineration
Site Remediation
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Solid Waste Treatment, Storage and
Disposal Facilities (TSDF)
Publicly Owned Treatment Works (POTW) Emissions
Agricultural Chemicals Production
Category Name
2.4-D Salts and Esters Production
4-Chloro-2-Methylphenoxyacetic Acid Production
4.6-Dinitro-o-Cresol Production
Captafol Production
Captan Production
Chloroneb Production
Chlorothalonil Production
Dacthal (tm) Production
Sodium Pentachlorophenate Production
Tordon (tm) Acid Production
Fibers Production Processes
Category Name
Acrylic Fibers/Modacrylic Fibers Production
Rayon Production
Spandex Production
Food and Agricultural Processes
Category Name
Baker's Yeast Manufacturing
Cellulose Food Casing Manufacturing
Vegetable Oil Production
Pharmaceutical Production Processes
Category Name
Pharmaceutical Production
Polymers and Resins Production
Category Name
Acetal Resins Production
Acrylonitrile-Butadiene-Styrene Production
Alkyd Resins Production
Amino Resins Production
Boat Manufacturing
Butadiene-Furfural Cotrimer (R-ll)
Butyl Rubber Production
Carboxymethylcellulose Production
Cellophane Production
Cellulose Ethers Production
Epichlorohydrin Elastomers Production
Epoxy Resins Production
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Ethylene-Propylene Elastomers Production
Flexible Polyurethane Foam Production
Hypalon (tm) Production
Maleic Anhydride Copolymers Production
Methylcellulose Production
Methylcellulose Production
Methyl Methacrylate-Acrylonitrile-Butadiene-
Styrene Production
Methyl Methacrylate-Butadiene-Styrene Terpolymers
Production
Neoprene Production
Nitrile Butadiene Rubber Production
Non-Nylon Polyamides Production
Nylon 6 Production
Phenolic Resins Production
Polybutadiene Rubber Production
Polycarbonates Production
Polyester Resins Production
Polyethylene Teraphthalate Production
Polymerized Vinylidene Chloride Production
Polymethyl Methacrylate Resins Production
Polystyrene Production
Polysulfide Rubber Production
Polyvinyl Acetate Emulsions Production
Polyvinyl Alcohol Production
Polyvinyl Butyral Production
Polyvinyl Chloride and Copolymers Production
Reinforced Plastic Composites Production
Styrene-Acrylonitrile Production
Styrene-Butadiene Rubber and Latex Production
Production of Inorganic Chemicals
Category Name
Ammonium Sulfate Production-Captrolactam
By-Product Plants
Antimony Oxides Manufacturing
Chlorine Production
Chromium Chemicals Manufacturing
Cyanuric Chloride Production
Fume Silica Production
Hydrochloric Acid Production
Hydrogen Cyanide Production
Hydrogen Fluoride Production
Phosphate Fertilizers Production
Phosphoric Acid Manufacturing
Quaternary Ammonium Compounds Production
Sodium Cyanide Production
Uranium Hexafluoride Production
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Production of Organic Chemicals
Category Name
Synthetic Organic Chemical Manufacturing
Miscellaneous Processes
Category Name
Aerosol Can-Filling Facilities
Benzyltrimethylammonium Chloride Production
Butadiene Dimers Production
Carbonyl Sulfide Production
Chelating Agents Production
Chlorinated Paraffins Production
Chromic Acid Anodizing
Commercial Dry Cleaning (Perchloroethylene)
Transfer Machines
Commercial Sterilization Facilities
Decorative Chromium Electroplating
Dodencanedioic Acid Production
Dry Cleaning (Petroleum Solvent)
Ethylidene Norbornene Production
Explosives Production
Halogenated Solvent Cleaners
Hard Chromium Electroplating
Hydrazine Production
Industrial Dry Cleaning (Perchloroethylene)
Transfer Machines
Industrial Dry Cleaning (Perchloroethylene)
Dry-to-Dry Machines
Industrial Process Cooling Towers
OBPA/1,3-Diisocyanate Production
Paint Stripper Users
Photographic Chemicals Production
Phthalate Plasticizers Production
Plywood/Particle Board Manufacturing
Polyether Polyols Production
Pulp and Paper Production
Rocket Engine Test Firing
Rubber Chemicals Manufacturing
Semiconductor Manufacturing
Symmetrical Tetrachloropyridine Production
Tire Production
Wood Treatment
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