Appendix Y to Part 51 - Guidelines for BART Determinations Under the Regional Haze Rule
40:2.0.1.1.2.25.11.20.40 : Appendix Y
Appendix Y to Part 51 - Guidelines for BART Determinations Under
the Regional Haze Rule Table of Contents I. Introduction and
Overview A. What is the purpose of the guidelines? B. What does the
CAA require generally for improving visibility? C. What is the BART
requirement in the CAA? D. What types of visibility problems does
EPA address in its regulations? E. What are the BART requirements
in EPA's regional haze regulations? F. What is included in the
guidelines? G. Who is the target audience for the guidelines? H. Do
EPA regulations require the use of these guidelines? II. How to
Identify BART-eligible Sources A. What are the steps in identifying
BART-eligible sources? 1. Step 1: Identify emission units in the
BART categories 2. Step 2: Identify the start-up dates of the
emission units 3. Step 3: Compare the potential emissions to the
250 ton/yr cutoff 4. Final step: Identify the emission units and
pollutants that constitute the BART-eligible source. III. How to
Identify Sources “Subject to BART” IV. The BART Determination:
Analysis of BART Options A. What factors must I address in the BART
Analysis? B. What is the scope of the BART review? C. How does a
BART review relate to maximum achievable control technology (MACT)
standards under CAA section 112? D. What are the five basic steps
of a case-by-case BART analysis? 1. Step 1: How do I identify all
available retrofit emission control techniques? 2. Step 2: How do I
determine whether the options identified in Step 1 are technically
feasible? 3. Step 3: How do I evaluate technically feasible
alternatives? 4. Step 4: For a BART review, what impacts am I
expected to calculate and report? What methods does EPA recommend
for the impacts analyses? a. Impact analysis part 1: how do I
estimate the costs of control? b. What do we mean by cost
effectiveness? c. How do I calculate average cost effectiveness? d.
How do I calculate baseline emissions? e. How do I calculate
incremental cost effectiveness? f. What other information should I
provide in the cost impacts analysis? g. What other things are
important to consider in the cost impacts analysis? h. Impact
analysis part 2: How should I analyze and report energy impacts? i.
Impact analysis part 3: How do I analyze “non-air quality
environmental impacts?” j. Impact analysis part 4: What are
examples of non-air quality environmental impacts? k. How do I take
into account a project's “remaining useful life” in calculating
control costs? 5. Step 5: How should I determine visibility impacts
in the BART determination? E. How do I select the “best”
alternative, using the results of Steps 1 through 5? 1. Summary of
the impacts analysis 2. Selecting a “best” alternative 3. In
selecting a “best” alternative, should I consider the affordability
of controls? 4. SO2 limits for utility boilers 5. NOX limits for
utility boilers V. Enforceable Limits/Compliance Date I.
Introduction and Overview A. What is the purpose of the guidelines?
The Clean Air Act (CAA), in sections 169A and 169B, contains
requirements for the protection of visibility in 156 scenic areas
across the United States. To meet the CAA's requirements, we
published regulations to protect against a particular type of
visibility impairment known as “regional haze.” The regional haze
rule is found in this part at 40 CFR 51.300 through 51.309. These
regulations require, in 40 CFR 51.308(e), that certain types of
existing stationary sources of air pollutants install best
available retrofit technology (BART). The guidelines are designed
to help States and others (1) identify those sources that must
comply with the BART requirement, and (2) determine the level of
control technology that represents BART for each source.
B. What does the CAA require generally for improving visibility?
Section 169A of the CAA, added to the CAA by the 1977
amendments, requires States to protect and improve visibility in
certain scenic areas of national importance. The scenic areas
protected by section 169A are “the mandatory Class I Federal Areas
* * * where visibility is an important value.” In these guidelines,
we refer to these as “Class I areas.” There are 156 Class I areas,
including 47 national parks (under the jurisdiction of the
Department of Interior - National Park Service), 108 wilderness
areas (under the jurisdiction of the Department of the Interior -
Fish and Wildlife Service or the Department of Agriculture - U.S.
Forest Service), and one International Park (under the jurisdiction
of the Roosevelt-Campobello International Commission). The Federal
Agency with jurisdiction over a particular Class I area is referred
to in the CAA as the Federal Land Manager. A complete list of the
Class I areas is contained in 40 CFR 81.401 through 81.437, and you
can find a map of the Class I areas at the following Internet site:
http://www.epa.gov/ttn/oarpg/t1/fr_notices/classimp.gif.
The CAA establishes a national goal of eliminating man-made
visibility impairment from all Class I areas. As part of the plan
for achieving this goal, the visibility protection provisions in
the CAA mandate that EPA issue regulations requiring that States
adopt measures in their State implementation plans (SIPs),
including long-term strategies, to provide for reasonable progress
towards this national goal. The CAA also requires States to
coordinate with the Federal Land Managers as they develop their
strategies for addressing visibility.
C. What is the BART requirement in the CAA?
1. Under section 169A(b)(2)(A) of the CAA, States must require
certain existing stationary sources to install BART. The BART
provision applies to “major stationary sources” from 26 identified
source categories which have the potential to emit 250 tons per
year or more of any air pollutant. The CAA requires only sources
which were put in place during a specific 15-year time interval to
be subject to BART. The BART provision applies to sources that
existed as of the date of the 1977 CAA amendments (that is, August
7, 1977) but which had not been in operation for more than 15 years
(that is, not in operation as of August 7, 1962).
2. The CAA requires BART review when any source meeting the
above description “emits any air pollutant which may reasonably be
anticipated to cause or contribute to any impairment of visibility”
in any Class I area. In identifying a level of control as BART,
States are required by section 169A(g) of the CAA to consider:
(a) The costs of compliance,
(b) The energy and non-air quality environmental impacts of
compliance,
(c) Any existing pollution control technology in use at the
source,
(d) The remaining useful life of the source, and
(e) The degree of visibility improvement which may reasonably be
anticipated from the use of BART.
3. The CAA further requires States to make BART emission
limitations part of their SIPs. As with any SIP revision, States
must provide an opportunity for public comment on the BART
determinations, and EPA's action on any SIP revision will be
subject to judicial review.
D. What types of visibility problems does EPA address in its
regulations?
1. We addressed the problem of visibility in two phases. In
1980, we published regulations addressing what we termed
“reasonably attributable” visibility impairment. Reasonably
attributable visibility impairment is the result of emissions from
one or a few sources that are generally located in close proximity
to a specific Class I area. The regulations addressing reasonably
attributable visibility impairment are published in 40 CFR 51.300
through 51.307.
2. On July 1, 1999, we amended these regulations to address the
second, more common, type of visibility impairment known as
“regional haze.” Regional haze is the result of the collective
contribution of many sources over a broad region. The regional haze
rule slightly modified 40 CFR 51.300 through 51.307, including the
addition of a few definitions in § 51.301, and added new §§ 51.308
and 51.309.
E. What are the BART requirements in EPA's regional haze
regulations?
1. In the July 1, 1999 rulemaking, we added a BART requirement
for regional haze. We amended the BART requirements in 2005. You
will find the BART requirements in 40 CFR 51.308(e). Definitions of
terms used in 40 CFR 51.308(e)(1) are found in 40 CFR 51.301.
2. As we discuss in detail in these guidelines, the regional
haze rule codifies and clarifies the BART provisions in the CAA.
The rule requires that States identify and list “BART-eligible
sources,” that is, that States identify and list those sources that
fall within the 26 source categories, were put in place during the
15-year window of time from 1962 to 1977, and have potential
emissions greater than 250 tons per year. Once the State has
identified the BART-eligible sources, the next step is to identify
those BART-eligible sources that may “emit any air pollutant which
may reasonably be anticipated to cause or contribute to any
impairment of visibility.” Under the rule, a source which fits this
description is “subject to BART.” For each source subject to BART,
40 CFR 51.308(e)(1)(ii)(A) requires that States identify the level
of control representing BART after considering the factors set out
in CAA section 169A(g), as follows:
- States must identify the best system of continuous emission
control technology for each source subject to BART taking into
account the technology available, the costs of compliance, the
energy and non-air quality environmental impacts of compliance, any
pollution control equipment in use at the source, the remaining
useful life of the source, and the degree of visibility improvement
that may be expected from available control technology.
3. After a State has identified the level of control
representing BART (if any), it must establish an emission limit
representing BART and must ensure compliance with that requirement
no later than 5 years after EPA approves the SIP. States may
establish design, equipment, work practice or other operational
standards when limitations on measurement technologies make
emission standards infeasible.
F. What is included in the guidelines?
1. The guidelines provide a process for making BART
determinations that States can use in implementing the regional
haze BART requirements on a source-by-source basis, as provided in
40 CFR 51.308(e)(1). States must follow the guidelines in making
BART determinations on a source-by-source basis for 750 megawatt
(MW) power plants but are not required to use the process in the
guidelines when making BART determinations for other types of
sources.
2. The BART analysis process, and the contents of these
guidelines, are as follows:
(a) Identification of all BART-eligible sources. Section
II of these guidelines outlines a step-by-step process for
identifying BART-eligible sources.
(b) Identification of sources subject to BART. As noted
above, sources “subject to BART” are those BART-eligible sources
which “emit a pollutant which may reasonably be anticipated to
cause or contribute to any impairment of visibility in any Class I
area.” We discuss considerations for identifying sources subject to
BART in section III of the guidance.
(c) The BART determination process. For each source
subject to BART, the next step is to conduct an analysis of
emissions control alternatives. This step includes the
identification of available, technically feasible retrofit
technologies, and for each technology identified, an analysis of
the cost of compliance, the energy and non-air quality
environmental impacts, and the degree of visibility improvement in
affected Class I areas resulting from the use of the control
technology. As part of the BART analysis, the State should also
take into account the remaining useful life of the source and any
existing control technology present at the source. For each source,
the State will determine a “best system of continuous emission
reduction” based upon its evaluation of these factors. Procedures
for the BART determination step are described in section IV of
these guidelines.
(d) Emissions limits. States must establish emission
limits, including a deadline for compliance, consistent with the
BART determination process for each source subject to BART.
Considerations related to these limits are discussed in section V
of these guidelines.
G. Who is the target audience for the guidelines?
1. The guidelines are written primarily for the benefit of
State, local and Tribal agencies, and describe a process for making
the BART determinations and establishing the emission limitations
that must be included in their SIPs or Tribal implementation plans
(TIPs). Throughout the guidelines, which are written in a question
and answer format, we ask questions “How do I * * *?” and answer
with phrases “you should * * *, you must * * *” The “you” means a
State, local or Tribal agency conducting the analysis. We have used
this format to make the guidelines simpler to understand, but we
recognize that States have the authority to require source owners
to assume part of the analytical burden, and that there will be
differences in how the supporting information is collected and
documented. We also recognize that data collection, analysis, and
rule development may be performed by Regional Planning
Organizations, for adoption within each SIP or TIP.
2. The preamble to the 1999 regional haze rule discussed at
length the issue of Tribal implementation of the requirements to
submit a plan to address visibility. As explained there,
requirements related to visibility are among the programs for which
Tribes may be determined eligible and receive authorization to
implement under the “Tribal Authority Rule” (“TAR”) (40 CFR 49.1
through 49.11). Tribes are not subject to the deadlines for
submitting visibility implementation plans and may use a modular
approach to CAA implementation. We believe there are very few
BART-eligible sources located on Tribal lands. Where such sources
exist, the affected Tribe may apply for delegation of
implementation authority for this rule, following the process set
forth in the TAR.
H. Do EPA regulations require the use of these guidelines?
Section 169A(b) requires us to issue guidelines for States to
follow in establishing BART emission limitations for fossil-fuel
fired power plants having a capacity in excess of 750 megawatts.
This document fulfills that requirement, which is codified in 40
CFR 51.308(e)(1)(ii)(B). The guidelines establish an approach to
implementing the requirements of the BART provisions of the
regional haze rule; we believe that these procedures and the
discussion of the requirements of the regional haze rule and the
CAA should be useful to the States. For sources other than 750 MW
power plants, however, States retain the discretion to adopt
approaches that differ from the guidelines.
II. How To Identify BART-Eligible Sources
This section provides guidelines on how to identify
BART-eligible sources. A BART-eligible source is an existing
stationary source in any of 26 listed categories which meets
criteria for startup dates and potential emissions.
A. What are the steps in identifying BART-eligible sources?
Figure 1 shows the steps for identifying whether the source is a
“BART-eligible source:”
Step 1: Identify the emission units in the BART categories,
Step 2: Identify the start-up dates of those emission units,
and
Step 3: Compare the potential emissions to the 250 ton/yr
cutoff.
Figure 1. How to determine whether a source is
BART-eligible:
Step 1: Identify emission units in the BART categories
Does the plant contain emissions units in one or more of the 26
source categories? ➜ No ➜ Stop ➜ Yes ➜ Proceed to Step 2
Step 2: Identify the start-up dates of these emission units
Do any of these emissions units meet the following two tests? In
existence on August 7, 1977
AND
Began operation after August 7, 1962 ➜ No ➜ Stop ➜ Yes ➜ Proceed to
Step 3
Step 3: Compare the potential emissions from these emission
units to the 250 ton/yr cutoff
Identify the “stationary source” that includes the emission units
you identified in Step 2. Add the current potential emissions from
all the emission units identified in Steps 1 and 2 that are
included within the “stationary source” boundary. Are the potential
emissions from these units 250 tons per year or more for any
visibility-impairing pollutant? ➜ No ➜ Stop ➜ Yes ➜ These emissions
units comprise the “BART-eligible source.” 1. Step 1: Identify
Emission Units in the BART Categories
1. The BART requirement only applies to sources in specific
categories listed in the CAA. The BART requirement does not apply
to sources in other source categories, regardless of their
emissions. The listed categories are:
(1) Fossil-fuel fired steam electric plants of more than 250
million British thermal units (BTU) per hour heat input,
(2) Coal cleaning plants (thermal dryers),
(3) Kraft pulp mills,
(4) Portland cement plants,
(5) Primary zinc smelters,
(6) Iron and steel mill plants,
(7) Primary aluminum ore reduction plants,
(8) Primary copper smelters,
(9) Municipal incinerators capable of charging more than 250
tons of refuse per day,
(10) Hydrofluoric, sulfuric, and nitric acid plants,
(11) Petroleum refineries,
(12) Lime plants,
(13) Phosphate rock processing plants,
(14) Coke oven batteries,
(15) Sulfur recovery plants,
(16) Carbon black plants (furnace process),
(17) Primary lead smelters,
(18) Fuel conversion plants,
(19) Sintering plants,
(20) Secondary metal production facilities,
(21) Chemical process plants,
(22) Fossil-fuel boilers of more than 250 million BTUs per hour
heat input,
(23) Petroleum storage and transfer facilities with a capacity
exceeding 300,000 barrels,
(24) Taconite ore processing facilities,
(25) Glass fiber processing plants, and
(26) Charcoal production facilities.
2. Some plants may have emission units from more than one
category, and some emitting equipment may fit into more than one
category. Examples of this situation are sulfur recovery plants at
petroleum refineries, coke oven batteries and sintering plants at
steel mills, and chemical process plants at refineries. For Step 1,
you identify all of the emissions units at the plant that fit into
one or more of the listed categories. You do not identify emission
units in other categories.
Example:A mine is collocated with an electric steam generating
plant and a coal cleaning plant. You would identify emission units
associated with the electric steam generating plant and the coal
cleaning plant, because they are listed categories, but not the
mine, because coal mining is not a listed category.
3. The category titles are generally clear in describing the
types of equipment to be listed. Most of the category titles are
very broad descriptions that encompass all emission units
associated with a plant site (for example, “petroleum refining” and
“kraft pulp mills”). This same list of categories appears in the
PSD regulations. States and source owners need not revisit any
interpretations of the list made previously for purposes of the PSD
program. We provide the following clarifications for a few of the
category titles:
(1) “Steam electric plants of more than 250 million BTU/hr
heat input.” Because the category refers to “plants,” we
interpret this category title to mean that boiler capacities should
be aggregated to determine whether the 250 million BTU/hr threshold
is reached. This definition includes only those plants that
generate electricity for sale. Plants that cogenerate steam and
electricity also fall within the definition of “steam electric
plants”. Similarly, combined cycle turbines are also considered
“steam electric plants” because such facilities incorporate heat
recovery steam generators. Simple cycle turbines, in contrast, are
not “steam electric plants” because these turbines typically do not
generate steam.
Example:A stationary source includes a steam electric plant with
three 100 million BTU/hr boilers. Because the aggregate capacity
exceeds 250 million BTU/hr for the “plant,” these boilers would be
identified in Step 2.
(2) “Fossil-fuel boilers of more than 250 million BTU/hr heat
input.” We interpret this category title to cover only those
boilers that are individually greater than 250 million BTU/hr.
However, an individual boiler smaller than 250 million BTU/hr
should be subject to BART if it is an integral part of a process
description at a plant that is in a different BART category - for
example, a boiler at a Kraft pulp mill that, in addition to
providing steam or mechanical power, uses the waste liquor from the
process as a fuel. In general, if the process uses any by-product
of the boiler and the boiler's function is to serve the process,
then the boiler is integral to the process and should be considered
to be part of the process description.
Also, you should consider a multi-fuel boiler to be a
“fossil-fuel boiler” if it burns any amount of fossil fuel. You may
take federally and State enforceable operational limits into
account in determining whether a multi-fuel boiler's fossil fuel
capacity exceeds 250 million Btu/hr.
(3) “Petroleum storage and transfer facilities with a
capacity exceeding 300,000 barrels.” The 300,000 barrel cutoff
refers to total facility-wide tank capacity for tanks that were put
in place within the 1962-1977 time period, and includes gasoline
and other petroleum-derived liquids.
(4) “Phosphate rock processing plants.” This category
descriptor is broad, and includes all types of phosphate rock
processing facilities, including elemental phosphorous plants as
well as fertilizer production plants.
(5) “Charcoal production facilities.” We interpret this
category to include charcoal briquet manufacturing and activated
carbon production.
(6) “Chemical process plants.” and pharmaceutical
manufacturing. Consistent with past policy, we interpret the
category “chemical process plants” to include those facilities
within the 2-digit Standard Industrial Classification (SIC) code
28. Accordingly, we interpret the term “chemical process plants” to
include pharmaceutical manufacturing facilities.
(7) “Secondary metal production.” We interpret this
category to include nonferrous metal facilities included within SIC
code 3341, and secondary ferrous metal facilities that we also
consider to be included within the category “iron and steel mill
plants.”
(8) “Primary aluminum ore reduction.” We interpret this
category to include those facilities covered by 40 CFR 60.190, the
new source performance standard (NSPS) for primary aluminum ore
reduction plants. This definition is also consistent with the
definition at 40 CFR 63.840.
2. Step 2: Identify the Start-Up Dates of the Emission Units
1. Emissions units listed under Step 1 are BART-eligible only if
they were “in existence” on August 7, 1977 but were not “in
operation” before August 7, 1962.
What does “in existence on August 7, 1977” mean?
2. The regional haze rule defines “in existence” to mean
that:
“the owner or operator has obtained all necessary
preconstruction approvals or permits required by Federal, State, or
local air pollution emissions and air quality laws or regulations
and either has (1) begun, or caused to begin, a continuous program
of physical on-site construction of the facility or (2) entered
into binding agreements or contractual obligations, which cannot be
canceled or modified without substantial loss to the owner or
operator, to undertake a program of construction of the facility to
be completed in a reasonable time.” 40 CFR 51.301.
As this definition is essentially identical to the definition of
“commence construction” as that term is used in the PSD
regulations, the two terms mean the same thing. See 40 CFR
51.165(a)(1)(xvi) and 40 CFR 52.21(b)(9). Under this definition, an
emissions unit could be “in existence” even if it did not begin
operating until several years after 1977.
Example:The owner of a source obtained all necessary permits in
early 1977 and entered into binding construction agreements in June
1977. Actual on-site construction began in late 1978, and
construction was completed in mid-1979. The source began operating
in September 1979. The emissions unit was “in existence” as of
August 7, 1977.
Major stationary sources which commenced construction AFTER
August 7, 1977 (i.e., major stationary sources which were
not “in existence” on August 7, 1977) were subject to new source
review (NSR) under the PSD program. Thus, the August 7, 1977 “in
existence” test is essentially the same thing as the identification
of emissions units that were grandfathered from the NSR review
requirements of the 1977 CAA amendments.
3. Sources are not BART-eligible if the only change at the plant
during the relevant time period was the addition of pollution
controls. For example, if the only change at a copper smelter
during the 1962 through 1977 time period was the addition of acid
plants for the reduction of SO2 emissions, these emission controls
would not by themselves trigger a BART review.
What does “in operation before August 7, 1962” mean?
An emissions unit that meets the August 7, 1977 “in existence”
test is not BART-eligible if it was in operation before August 7,
1962. “In operation” is defined as “engaged in activity related to
the primary design function of the source.” This means that a
source must have begun actual operations by August 7, 1962 to
satisfy this test.
Example:The owner or operator entered into binding agreements in
1960. Actual on-site construction began in 1961, and construction
was complete in mid-1962. The source began operating in September
1962. The emissions unit
was not “in operation” before
August 7, 1962 and is therefore subject to BART. What is a
“reconstructed source?'
1. Under a number of CAA programs, an existing source which is
completely or substantially rebuilt is treated as a new source.
Such “reconstructed” sources are treated as new sources as of the
time of the reconstruction. Consistent with this overall approach
to reconstructions, the definition of BART-eligible facility
(reflected in detail in the definition of “existing stationary
facility”) includes consideration of sources that were in operation
before August 7, 1962, but were reconstructed during the August 7,
1962 to August 7, 1977 time period.
2. Under the regional haze regulations at 40 CFR 51.301, a
reconstruction has taken place if “the fixed capital cost of the
new component exceeds 50 percent of the fixed capital cost of a
comparable entirely new source.” The rule also states that “[a]ny
final decision as to whether reconstruction has occurred must be
made in accordance with the provisions of §§ 60.15 (f)(1) through
(3) of this title.” “[T]he provisions of §§ 60.15(f)(1) through
(3)” refers to the general provisions for New Source Performance
Standards (NSPS). Thus, the same policies and procedures for
identifying reconstructed “affected facilities” under the NSPS
program must also be used to identify reconstructed “stationary
sources” for purposes of the BART requirement.
3. You should identify reconstructions on an emissions unit
basis, rather than on a plantwide basis. That is, you need to
identify only the reconstructed emission units meeting the 50
percent cost criterion. You should include reconstructed emission
units in the list of emission units you identified in Step 1. You
need consider as possible reconstructions only those emissions
units with the potential to emit more than 250 tons per year of any
visibility-impairing pollutant.
4. The “in operation” and “in existence” tests apply to
reconstructed sources. If an emissions unit was reconstructed and
began actual operation before August 7, 1962, it is not
BART-eligible. Similarly, any emissions unit for which a
reconstruction “commenced” after August 7, 1977, is not
BART-eligible.
How are modifications treated under the BART provision?
1. The NSPS program and the major source NSR program both
contain the concept of modifications. In general, the term
“modification” refers to any physical change or change in the
method of operation of an emissions unit that results in an
increase in emissions.
2. The BART provision in the regional haze rule contains no
explicit treatment of modifications or how modified emissions
units, previously subject to the requirement to install best
available control technology (BACT), lowest achievable emission
rate (LAER) controls, and/or NSPS are treated under the rule. As
the BART requirements in the CAA do not appear to provide any
exemption for sources which have been modified since 1977, the best
interpretation of the CAA visibility provisions is that a
subsequent modification does not change a unit's construction date
for the purpose of BART applicability. Accordingly, if an emissions
unit began operation before 1962, it is not BART-eligible if it was
modified between 1962 and 1977, so long as the modification is not
also a “reconstruction.” On the other hand, an emissions unit which
began operation within the 1962-1977 time window, but was modified
after August 7, 1977, is BART-eligible. We note, however, that if
such a modification was a major modification that resulted in the
installation of controls, the State will take this into account
during the review process and may find that the level of controls
already in place are consistent with BART.
3. Step 3: Compare the Potential Emissions to the 250 Ton/Yr Cutoff
The result of Steps 1 and 2 will be a list of emissions units at
a given plant site, including reconstructed emissions units, that
are within one or more of the BART categories and that were placed
into operation within the 1962-1977 time window. The third step is
to determine whether the total emissions represent a current
potential to emit that is greater than 250 tons per year of any
single visibility impairing pollutant. Fugitive emissions, to the
extent quantifiable, must be counted. In most cases, you will add
the potential emissions from all emission units on the list
resulting from Steps 1 and 2. In a few cases, you may need to
determine whether the plant contains more than one “stationary
source” as the regional haze rule defines that term, and as we
explain further below.
What pollutants should I address?
Visibility-impairing pollutants include the following:
(1) Sulfur dioxide (SO2),
(2) Nitrogen oxides (NOX), and
(3) Particulate matter.
You may use PM10 as an indicator for particulate matter in this
intial step. [Note that we do not recommend use of total suspended
particulates (TSP) as in indicator for particulate matter.] As
emissions of PM10 include the components of PM2.5 as a subset,
there is no need to have separate 250 ton thresholds for PM10 and
PM2.5; 250 tons of PM10 represents at most 250 tons of PM2.5, and
at most 250 tons of any individual particulate species such as
elemental carbon, crustal material, etc.
However, if you determine that a source of particulate matter is
BART-eligible, it will be important to distinguish between the fine
and coarse particle components of direct particulate emissions in
the remainder of the BART analysis, including for the purpose of
modeling the source's impact on visibility. This is because
although both fine and coarse particulate matter contribute to
visibility impairment, the long-range transport of fine particles
is of particular concern in the formation of regional haze. Thus,
for example, air quality modeling results used in the BART
determination will provide a more accurate prediction of a source's
impact on visibility if the inputs into the model account for the
relative particle size of any directly emitted particulate matter
(i.e. PM10 vs. PM2.5).
You should exercise judgment in deciding whether the following
pollutants impair visibility in an area:
(4) Volatile organic compounds (VOC), and
(5) Ammonia and ammonia compounds.
You should use your best judgment in deciding whether VOC or
ammonia emissions from a source are likely to have an impact on
visibility in an area. Certain types of VOC emissions, for example,
are more likely to form secondary organic aerosols than others. 1
Similarly, controlling ammonia emissions in some areas may not have
a significant impact on visibility. You need not provide a formal
showing of an individual decision that a source of VOC or ammonia
emissions is not subject to BART review. Because air quality
modeling may not be feasible for individual sources of VOC or
ammonia, you should also exercise your judgement in assessing the
degree of visibility impacts due to emissions of VOC and emissions
of ammonia or ammonia compounds. You should fully document the
basis for judging that a VOC or ammonia source merits BART review,
including your assessment of the source's contribution to
visibility impairment.
1 Fine particles: Overview of Atmospheric Chemistry, Sources
of Emissions, and Ambient Monitoring Data, Memorandum to Docket
OAR 2002-006, April 1, 2005.
What does the term “potential” emissions mean?
The regional haze rule defines potential to emit as follows:
“Potential to emit” means the maximum capacity of a stationary
source to emit a pollutant under its physical and operational
design. Any physical or operational limitation on the capacity of
the source to emit a pollutant including air pollution control
equipment and restrictions on hours 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. Secondary
emissions do not count in determining the potential to emit of a
stationary source.
The definition of “potential to emit” means that a source which
actually emits less than 250 tons per year of a
visibility-impairing pollutant is BART-eligible if its emissions
would exceed 250 tons per year when operating at its maximum
capacity given its physical and operational design (and considering
all federally enforceable and State enforceable permit limits.)
Example:A source, while operating at one-fourth of its capacity,
emits 75 tons per year of SO2. If it were operating at 100 percent
of its maximum capacity, the source would emit 300 tons per year.
Because under the above definition such a source would have
“potential” emissions that exceed 250 tons per year, the source (if
in a listed category and built during the 1962-1977 time window)
would be BART-eligible. How do I identify whether a plant has more
than one “stationary source?”
1. The regional haze rule, in 40 CFR 51.301, defines a
stationary source as a “building, structure, facility or
installation which emits or may emit any air pollutant.” 2 The rule
further defines “building, structure or facility” as:
2 Note: Most of these terms and definitions are the same for
regional haze and the 1980 visibility regulations. For the regional
haze rule we use the term “BART-eligible source” rather than
“existing stationary facility” to clarify that only a limited
subset of existing stationary sources are subject to BART.
all of the pollutant-emitting activities which belong to the same
industrial grouping, are located on one or more contiguous or
adjacent properties, and are under the control of the same person
(or persons under common control). Pollutant-emitting activities
must be considered as part of the same industrial grouping if they
belong to the same Major Group (
i.e., which have the same
two-digit code) as described in the Standard Industrial
Classification Manual, 1972 as amended by the 1977 Supplement (U.S.
Government Printing Office stock numbers 4101-0066 and
003-005-00176-0, respectively).
2. In applying this definition, it is necessary to determine
which facilities are located on “contiguous or adjacent
properties.” Within this contiguous and adjacent area, it is also
necessary to group those emission units that are under “common
control.” We note that these plant boundary issues and “common
control” issues are very similar to those already addressed in
implementation of the title V operating permits program and in
NSR.
3. For emission units within the “contiguous or adjacent”
boundary and under common control, you must group emission units
that are within the same industrial grouping (that is, associated
with the same 2-digit SIC code) in order to define the stationary
source. 3 For most plants on the BART source category list, there
will only be one 2-digit SIC that applies to the entire plant. For
example, all emission units associated with kraft pulp mills are
within SIC code 26, and chemical process plants will generally
include emission units that are all within SIC code 28. The
“2-digit SIC test” applies in the same way as the test is applied
in the major source NSR programs. 4
3 We recognize that we are in a transition period from the use
of the SIC system to a new system called the North American
Industry Classification System (NAICS). For purposes of identifying
BART-eligible sources, you may use either 2-digit SICS or the
equivalent in the NAICS system.
4 Note: The concept of support facility used for the NSR program
applies here as well. Support facilities, that is facilities that
convey, store or otherwise assist in the production of the
principal product, must be grouped with primary facilities even
when the facilities fall wihin separate SIC codes. For purposes of
BART reviews, however, such support facilities (a) must be within
one of the 26 listed source categories and (b) must have been in
existence as of August 7, 1977, and (c) must not have been in
operation as of August 7, 1962.
4. For purposes of the regional haze rule, you must group
emissions from all emission units put in place within the 1962-1977
time period that are within the 2-digit SIC code, even if those
emission units are in different categories on the BART category
list.
Examples:A chemical plant which started operations within the 1962
to 1977 time period manufactures hydrochloric acid (within the
category title “Hydrochloric, sulfuric, and nitric acid plants”)
and various organic chemicals (within the category title “chemical
process plants”). All of the emission units are within SIC code 28
and, therefore, all the emission units are considered in
determining BART eligibility of the plant. You sum the emissions
over all of these emission units to see whether there are more than
250 tons per year of potential emissions.
A steel mill which started operations within the 1962 to 1977
time period includes a sintering plant, a coke oven battery, and
various other emission units. All of the emission units are within
SIC code 33. You sum the emissions over all of these emission units
to see whether there are more than 250 tons per year of potential
emissions.
4. Final Step: Identify the Emissions Units and Pollutants That
Constitute the BART-Eligible Source
If the emissions from the list of emissions units at a
stationary source exceed a potential to emit of 250 tons per year
for any visibility-impairing pollutant, then that collection of
emissions units is a BART-eligible source.
Example:A stationary source comprises the following two emissions
units, with the following potential emissions: Emissions unit A 200
tons/yr SO2 150 tons/yr NOX 25 tons/yr PM Emissions unit B 100
tons/yr SO2 75 tons/yr NOX 10 tons/yr PM For this example,
potential emissions of SO2 are 300 tons/yr, which exceeds the 250
tons/yr threshold. Accordingly, the entire “stationary source”,
that is, emissions units A and B, may be subject to a BART review
for SO2, NOX, and PM, even though the potential emissions of PM and
NOX at each emissions unit are less than 250 tons/yr each.
Example:The total potential emissions, obtained by adding the
potential emissions of all emission units in a listed category at a
plant site, are as follows: 200 tons/yr SO2 150 tons/yr NOX 25
tons/yr PM
Even though total emissions exceed 250 tons/yr, no individual
regulated pollutant exceeds 250 tons/yr and this source is not
BART-eligible.
Can States establish de minimis levels of emissions for pollutants
at BART-eligible sources?
In order to simplify BART determinations, States may choose to
identify de minimis levels of pollutants at BART-eligible sources
(but are not required to do so). De minimis values should be
identified with the purpose of excluding only those emissions so
minimal that they are unlikely to contribute to regional haze. Any
de minimis values that you adopt must not be higher than the PSD
applicability levels: 40 tons/yr for SO2 and NOX and 15 tons/yr for
PM10. These de minimis levels may only be applied on a plant-wide
basis.
III. How To Identify Sources “Subject to BART”
Once you have compiled your list of BART-eligible sources, you
need to determine whether (1) to make BART determinations for all
of them or (2) to consider exempting some of them from BART because
they may not reasonably be anticipated to cause or contribute to
any visibility impairment in a Class I area. If you decide to make
BART determinations for all the BART-eligible sources on your list,
you should work with your regional planning organization (RPO) to
show that, collectively, they cause or contribute to visibility
impairment in at least one Class I area. You should then make
individual BART determinations by applying the five statutory
factors discussed in Section IV below.
On the other hand, you also may choose to perform an initial
examination to determine whether a particular BART-eligible source
or group of sources causes or contributes to visibility impairment
in nearby Class I areas. If your analysis, or information submitted
by the source, shows that an individual source or group of sources
(or certain pollutants from those sources) is not reasonably
anticipated to cause or contribute to any visibility impairment in
a Class I area, then you do not need to make BART determinations
for that source or group of sources (or for certain pollutants from
those sources). In such a case, the source is not “subject to BART”
and you do not need to apply the five statutory factors to make a
BART determination. This section of the Guideline discusses several
approaches that you can use to exempt sources from the BART
determination process.
A. What Steps Do I Follow To Determine Whether a Source or Group of
Sources Cause or Contribute to Visibility Impairment for Purposes
of BART? 1. How Do I Establish a Threshold?
One of the first steps in determining whether sources cause or
contribute to visibility impairment for purposes of BART is to
establish a threshold (measured in deciviews) against which to
measure the visibility impact of one or more sources. A single
source that is responsible for a 1.0 deciview change or more should
be considered to “cause” visibility impairment; a source that
causes less than a 1.0 deciview change may still contribute to
visibility impairment and thus be subject to BART.
Because of varying circumstances affecting different Class I
areas, the appropriate threshold for determining whether a source
“contributes to any visibility impairment” for the purposes of BART
may reasonably differ across States. As a general matter, any
threshold that you use for determining whether a source
“contributes” to visibility impairment should not be higher than
0.5 deciviews.
In setting a threshold for “contribution,” you should consider
the number of emissions sources affecting the Class I areas at
issue and the magnitude of the individual sources' impacts. 5 In
general, a larger number of sources causing impacts in a Class I
area may warrant a lower contribution threshold. States remain free
to use a threshold lower than 0.5 deciviews if they conclude that
the location of a large number of BART-eligible sources within the
State and in proximity to a Class I area justify this approach.
6
5 We expect that regional planning organizations will have
modeling information that identifies sources affecting visibility
in individual class I areas.
6 Note that the contribution threshold should be used to
determine whether an individual source is reasonably anticipated to
contribute to visibility impairment. You should not aggregate the
visibility effects of multiple sources and compare their collective
effects against your contribution threshold because this would
inappropriately create a “contribute to contribution” test.
2. What Pollutants Do I Need To Consider?
You must look at SO2, NOX, and direct particulate matter (PM)
emissions in determining whether sources cause or contribute to
visibility impairment, including both PM10 and PM2.5. Consistent
with the approach for identifying your BART-eligible sources, you
do not need to consider less than de minimis emissions of these
pollutants from a source.
As explained in section II, you must use your best judgement to
determine whether VOC or ammonia emissions are likely to have an
impact on visibility in an area. In addition, although as explained
in Section II, you may use PM10 an indicator for particulate matter
in determining whether a source is BART-eligible, in determining
whether a source contributes to visibility impairment, you should
distinguish between the fine and coarse particle components of
direct particulate emissions. Although both fine and coarse
particulate matter contribute to visibility impairment, the
long-range transport of fine particles is of particular concern in
the formation of regional haze. Air quality modeling results used
in the BART determination will provide a more accurate prediction
of a source's impact on visibility if the inputs into the model
account for the relative particle size of any directly emitted
particulate matter (i.e., PM10 vs. PM2.5).
3. What Kind of Modeling Should I Use To Determine Which Sources
and Pollutants Need Not Be Subject to BART?
This section presents several options for determining that
certain sources need not be subject to BART. These options rely on
different modeling and/or emissions analysis approaches. They are
provided for your guidance. You may also use other reasonable
approaches for analyzing the visibility impacts of an individual
source or group of sources.
Option 1: Individual Source Attribution Approach (Dispersion
Modeling)
You can use dispersion modeling to determine that an individual
source cannot reasonably be anticipated to cause or contribute to
visibility impairment in a Class I area and thus is not subject to
BART. Under this option, you can analyze an individual source's
impact on visibility as a result of its emissions of SO2, NOX and
direct PM emissions. Dispersion modeling cannot currently be used
to estimate the predicted impacts on visibility from an individual
source's emissions of VOC or ammonia. You may use a more
qualitative assessment to determine on a case-by-case basis which
sources of VOC or ammonia emissions may be likely to impair
visibility and should therefore be subject to BART review, as
explained in section II.A.3. above.
You can use CALPUFF 7 or other appropriate model to predict the
visibility impacts from a single source at a Class I area. CALPUFF
is the best regulatory modeling application currently available for
predicting a single source's contribution to visibility impairment
and is currently the only EPA-approved model for use in estimating
single source pollutant concentrations resulting from the long
range transport of primary pollutants. 8 It can also be used for
some other purposes, such as the visibility assessments addressed
in today's rule, to account for the chemical transformation of SO2
and NOX.
7 The model code and its documentation are available at no cost
for download from
http://www.epa.gov/scram001/tt22.htm#calpuff.
8 The Guideline on Air Quality Models, 40 CFR part 51, appendix
W, addresses the regulatory application of air quality models for
assessing criteria pollutants under the CAA, and describes further
the procedures for using the CALPUFF model, as well as for
obtaining approval for the use of other, nonguideline models.
There are several steps for making an individual source
attribution using a dispersion model:
1. Develop a modeling protocol. Some critical items to
include in the protocol are the meteorological and terrain data
that will be used, as well as the source-specific information
(stack height, temperature, exit velocity, elevation, and emission
rates of applicable pollutants) and receptor data from appropriate
Class I areas. We recommend following EPA's Interagency
Workgroup on Air Quality Modeling (IWAQM) Phase 2 Summary Report
and Recommendations for Modeling Long Range Transport Impacts 9
for parameter settings and meteorological data inputs. You may use
other settings from those in IWAQM, but you should identify these
settings and explain your selection of these settings.
9 Interagency Workgroup on Air Quality Modeling (IWAQM) Phase
2 Summary Report and Recommendations for Modeling Long Range
Transport Impacts, U.S. Environmental Protection Agency,
EPA-454/R-98-019, December 1998.
One important element of the protocol is in establishing the
receptors that will be used in the model. The receptors that you
use should be located in the nearest Class I area with sufficient
density to identify the likely visibility effects of the source.
For other Class I areas in relatively close proximity to a
BART-eligible source, you may model a few strategic receptors to
determine whether effects at those areas may be greater than at the
nearest Class I area. For example, you might chose to locate
receptors at these areas at the closest point to the source, at the
highest and lowest elevation in the Class I area, at the IMPROVE
monitor, and at the approximate expected plume release height. If
the highest modeled effects are observed at the nearest Class I
area, you may choose not to analyze the other Class I areas any
further as additional analyses might be unwarranted.
You should bear in mind that some receptors within the relevant
Class I area may be less than 50 km from the source while other
receptors within that same Class I area may be greater than 50 km
from the same source. As indicated by the Guideline on Air Quality
Models, 40 CFR part 51, appendix W, this situation may call for the
use of two different modeling approaches for the same Class I area
and source, depending upon the State's chosen method for modeling
sources less than 50 km. In situations where you are assessing
visibility impacts for source-receptor distances less than 50 km,
you should use expert modeling judgment in determining visibility
impacts, giving consideration to both CALPUFF and other appropriate
methods.
In developing your modeling protocol, you may want to consult
with EPA and your regional planning organization (RPO). Up-front
consultation will ensure that key technical issues are addressed
before you conduct your modeling.
2. With the accepted protocol and compare the predicted
visibility impacts with your threshold for “contribution.” You
should calculate daily visibility values for each receptor as the
change in deciviews compared against natural visibility conditions.
You can use EPA's “Guidance for Estimating Natural Visibility
Conditions Under the Regional Haze Rule,” EPA-454/B-03-005
(September 2003) in making this calculation. To determine whether a
source may reasonably be anticipated to cause or contribute to
visibility impairment at Class I area, you then compare the impacts
predicted by the model against the threshold that you have
selected.
The emissions estimates used in the models are intended to
reflect steady-state operating conditions during periods of high
capacity utilization. We do not generally recommend that emissions
reflecting periods of start-up, shutdown, and malfunction be used,
as such emission rates could produce higher than normal effects
than would be typical of most facilities. We recommend that States
use the 24 hour average actual emission rate from the highest
emitting day of the meteorological period modeled, unless this rate
reflects periods start-up, shutdown, or malfunction. In addition,
the monthly average relative humidity is used, rather than the
daily average humidity - an approach that effectively lowers the
peak values in daily model averages.
For these reasons, if you use the modeling approach we
recommend, you should compare your “contribution” threshold against
the 98th percentile of values. If the 98th percentile value from
your modeling is less than your contribution threshold, then you
may conclude that the source does not contribute to visibility
impairment and is not subject to BART.
Option 2: Use of Model Plants To Exempt Individual Sources With
Common Characteristics
Under this option, analyses of model plants could be used to
exempt certain BART-eligible sources that share specific
characteristics. It may be most useful to use this type of analysis
to identify the types of small sources that do not cause or
contribute to visibility impairment for purposes of BART, and thus
should not be subject to a BART review. Different Class I areas may
have different characteristics, however, so you should use care to
ensure that the criteria you develop are appropriate for the
applicable cases.
In carrying out this approach, you could use modeling analyses
of representative plants to reflect groupings of specific sources
with important common characteristics. Based on these analyses, you
may find that certain types of sources are clearly anticipated to
cause or contribute to visibility impairment. You could then choose
to categorically require those types of sources to undergo a BART
determination. Conversely, you may find based on representative
plant analyses that certain types of sources are not reasonably
anticipated to cause or contribute to visibility impairment. To do
this, you may conduct your own modeling to establish emission
levels and distances from Class I areas on which you can rely to
exempt sources with those characteristics. For example, based on
your modeling you might choose to exempt all NOX-only sources that
emit less than a certain amount per year and are located a certain
distance from a Class I area. You could then choose to
categorically exempt such sources from the BART determination
process.
Our analyses of visibility impacts from model plants provide a
useful example of the type of analyses that can be used to exempt
categories of sources from BART. 10 In our analyses, we developed
model plants (EGUs and non-EGUs), with representative plume and
stack characteristics, for use in considering the visibility impact
from emission sources of different sizes and compositions at
distances of 50, 100 and 200 kilometers from two hypothetical Class
I areas (one in the East and one in the West). As the plume and
stack characteristics of these model plants were developed
considering the broad range of sources within the EGU and non-EGU
categories, they do not necessarily represent any specific plant.
However, the results of these analyses are instructive in the
development of an exemption process for any Class I area.
10 CALPUFF Analysis in Support of the June 2005 Changes to the
Regional Haze Rule, U.S. Environmental Protection Agency, June 15,
2005, Docket No. OAR-2002-0076.
In preparing our analyses, we have made a number of assumptions
and exercised certain modeling choices; some of these have a
tendency to lend conservatism to the results, overstating the
likely effects, while others may understate the likely effects. On
balance, when all of these factors are considered, we believe that
our examples reflect realistic treatments of the situations being
modeled. Based on our analyses, we believe that a State that has
established 0.5 deciviews as a contribution threshold could
reasonably exempt from the BART review process sources that emit
less than 500 tons per year of NOX or SO2 (or combined NOX and
SO2), as long as these sources are located more than 50 kilometers
from any Class I area; and sources that emit less than 1000 tons
per year of NOX or SO2 (or combined NOX and SO2) that are located
more than 100 kilometers from any Class I area. You do, however,
have the option of showing other thresholds might also be
appropriate given your specific circumstances.
Option 3: Cumulative Modeling To Show That No Sources in a State
Are Subject to BART
You may also submit to EPA a demonstration based on an analysis
of overall visibility impacts that emissions from BART-eligible
sources in your State, considered together, are not reasonably
anticipated to cause or contribute to any visibility impairment in
a Class I area, and thus no source should be subject to BART. You
may do this on a pollutant by pollutant basis or for all
visibility-impairing pollutants to determine if emissions from
these sources contribute to visibility impairment.
For example, emissions of SO2 from your BART-eligible sources
may clearly cause or contribute to visibility impairment while
direct emissions of PM2.5 from these sources may not contribute to
impairment. If you can make such a demonstration, then you may
reasonably conclude that none of your BART-eligible sources are
subject to BART for a particular pollutant or pollutants. As noted
above, your demonstration should take into account the interactions
among pollutants and their resulting impacts on visibility before
making any pollutant-specific determinations.
Analyses may be conducted using several alternative modeling
approaches. First, you may use the CALPUFF or other appropriate
model as described in Option 1 to evaluate the impacts of
individual sources on downwind Class I areas, aggregating those
impacts to determine the collective contribution of all
BART-eligible sources to visibility impairment. You may also use a
photochemical grid model. As a general matter, the larger the
number of sources being modeled, the more appropriate it may be to
use a photochemical grid model. However, because such models are
significantly less sensitive than dispersion models to the
contributions of one or a few sources, as well as to the
interactions among sources that are widely distributed
geographically, if you wish to use a grid model, you should consult
with the appropriate EPA Regional Office to develop an appropriate
modeling protocol.
IV. The BART Determination: Analysis of BART Options
This section describes the process for the analysis of control
options for sources subject to BART.
A. What factors must I address in the BART review?
The visibility regulations define BART as follows:
Best Available Retrofit Technology (BART) means an
emission limitation based on the degree of reduction achievable
through the application of the best system of continuous emission
reduction for each pollutant which is emitted by . . . [a
BART-eligible source]. The emission limitation must be established,
on a case-by-case basis, taking into consideration the technology
available, the costs of compliance, the energy and non-air quality
environmental impacts of compliance, any pollution control
equipment in use or in existence at the source, the remaining
useful life of the source, and the degree of improvement in
visibility which may reasonably be anticipated to result from the
use of such technology.
The BART analysis identifies the best system of continuous
emission reduction taking into account:
(1) The available retrofit control options,
(2) Any pollution control equipment in use at the source (which
affects the availability of options and their impacts),
(3) The costs of compliance with control options,
(4) The remaining useful life of the facility,
(5) The energy and non-air quality environmental impacts of
control options
(6) The visibility impacts analysis.
B. What is the scope of the BART review?
Once you determine that a source is subject to BART for a
particular pollutant, then for each affected emission unit, you
must establish BART for that pollutant. The BART determination must
address air pollution control measures for each emissions unit or
pollutant emitting activity subject to review.
Example:Plantwide emissions from emission units within the listed
categories that began operation within the “time window” for BART
11 are 300 tons/yr of NOX, 200 tons/yr of SO2, and 150 tons/yr of
primary particulate. Emissions unit A emits 200 tons/yr of NOX, 100
tons/yr of SO2, and 100 tons/yr of primary particulate. Other
emission units, units B through H, which began operating in 1966,
contribute lesser amounts of each pollutant. For this example, a
BART review is required for NOX, SO2, and primary particulate, and
control options must be analyzed for units B through H as well as
unit A.
11 That is, emission units that were in existence on August 7,
1977 and which began actual operation on or after August 7,
1962.
C. How does a BART review relate to Maximum Achievable Control
Technology (MACT) Standards under CAA section 112, or to other
emission limitations required under the CAA?
For VOC and PM sources subject to MACT standards, States may
streamline the analysis by including a discussion of the MACT
controls and whether any major new technologies have been developed
subsequent to the MACT standards. We believe that there are many
VOC and PM sources that are well controlled because they are
regulated by the MACT standards, which EPA developed under CAA
section 112. For a few MACT standards, this may also be true for
SO2. Any source subject to MACT standards must meet a level that is
as stringent as the best-controlled 12 percent of sources in the
industry. Examples of these hazardous air pollutant sources which
effectively control VOC and PM emissions include (among others)
secondary lead facilities, organic chemical plants subject to the
hazardous organic NESHAP (HON), pharmaceutical production
facilities, and equipment leaks and wastewater operations at
petroleum refineries. We believe that, in many cases, it will be
unlikely that States will identify emission controls more stringent
than the MACT standards without identifying control options that
would cost many thousands of dollars per ton. Unless there are new
technologies subsequent to the MACT standards which would lead to
cost-effective increases in the level of control, you may rely on
the MACT standards for purposes of BART.
We believe that the same rationale also holds true for emissions
standards developed for municipal waste incinerators under CAA
section 111(d), and for many NSR/PSD determinations and NSR/PSD
settlement agreements. However, we do not believe that technology
determinations from the 1970s or early 1980s, including new source
performance standards (NSPS), should be considered to represent
best control for existing sources, as best control levels for
recent plant retrofits are more stringent than these older
levels.
Where you are relying on these standards to represent a BART
level of control, you should provide the public with a discussion
of whether any new technologies have subsequently become
available.
D. What Are the Five Basic Steps of a Case-by-Case BART Analysis?
The five steps are:
STEP 1 - Identify All 12 Available Retrofit Control
Technologies,
12 In identifying “all” options, you must identify the most
stringent option and a reasonable set of options for analysis that
reflects a comprehensive list of available technologies. It is not
necessary to list all permutations of available control levels that
exist for a given technology - the list is complete if it includes
the maximum level of control each technology is capable of
achieving.
STEP 2 - Eliminate Technically Infeasible Options,
STEP 3 - Evaluate Control Effectiveness of Remaining Control
Technologies,
STEP 4 - Evaluate Impacts and Document the Results, and
STEP 5 - Evaluate Visibility Impacts.
1. STEP 1: How do I identify all available retrofit emission
control techniques?
1. Available retrofit control options are those air pollution
control technologies with a practical potential for application to
the emissions unit and the regulated pollutant under evaluation.
Air pollution control technologies can include a wide variety of
available methods, systems, and techniques for control of the
affected pollutant. Technologies required as BACT or LAER are
available for BART purposes and must be included as control
alternatives. The control alternatives can include not only
existing controls for the source category in question but also take
into account technology transfer of controls that have been applied
to similar source categories and gas streams. Technologies which
have not yet been applied to (or permitted for) full scale
operations need not be considered as available; we do not expect
the source owner to purchase or construct a process or control
device that has not already been demonstrated in practice.
2. Where a NSPS exists for a source category (which is the case
for most of the categories affected by BART), you should include a
level of control equivalent to the NSPS as one of the control
options. 13 The NSPS standards are codified in 40 CFR part 60. We
note that there are situations where NSPS standards do not require
the most stringent level of available control for all sources
within a category. For example, post-combustion NOX controls (the
most stringent controls for stationary gas turbines) are not
required under subpart GG of the NSPS for Stationary Gas Turbines.
However, such controls must still be considered available
technologies for the BART selection process.
13 In EPA's 1980 BART guidelines for reasonably attributable
visibility impairment, we concluded that NSPS standards generally,
at that time, represented the best level sources could install as
BART. In the 20 year period since this guidance was developed,
there have been advances in SO2 control technologies as well as
technologies for the control of other pollutants, confirmed by a
number of recent retrofits at Western power plants. Accordingly,
EPA no longer concludes that the NSPS level of controls
automatically represents “the best these sources can install.”
Analysis of the BART factors could result in the selection of a
NSPS level of control, but you should reach this conclusion only
after considering the full range of control options.
3. Potentially applicable retrofit control alternatives can be
categorized in three ways.
• Pollution prevention: use of inherently lower-emitting
processes/practices, including the use of control techniques (e.g.,
low-NOX burners) and work practices that prevent emissions and
result in lower “production-specific” emissions (note that it is
not our intent to direct States to switch fuel forms, e.g., from
coal to gas),
• Use of (and where already in place, improvement in the
performance of) add-on controls, such as scrubbers, fabric filters,
thermal oxidizers and other devices that control and reduce
emissions after they are produced, and
• Combinations of inherently lower-emitting processes and add-on
controls.
4. In the course of the BART review, one or more of the
available control options may be eliminated from consideration
because they are demonstrated to be technically infeasible or to
have unacceptable energy, cost, or non-air quality environmental
impacts on a case-by-case (or site-specific) basis. However, at the
outset, you should initially identify all control options with
potential application to the emissions unit under review.
5. We do not consider BART as a requirement to redesign the
source when considering available control alternatives. For
example, where the source subject to BART is a coal-fired electric
generator, we do not require the BART analysis to consider building
a natural gas-fired electric turbine although the turbine may be
inherently less polluting on a per unit basis.
6. For emission units subject to a BART review, there will often
be control measures or devices already in place. For such emission
units, it is important to include control options that involve
improvements to existing controls and not to limit the control
options only to those measures that involve a complete replacement
of control devices.
Example:For a power plant with an existing wet scrubber, the
current control efficiency is 66 percent. Part of the reason for
the relatively low control efficiency is that 22 percent of the gas
stream bypasses the scrubber. A BART review identifies options for
improving the performance of the wet scrubber by redesigning the
internal components of the scrubber and by eliminating or reducing
the percentage of the gas stream that bypasses the scrubber. Four
control options are identified: (1) 78 percent control based upon
improved scrubber performance while maintaining the 22 percent
bypass, (2) 83 percent control based upon improved scrubber
performance while reducing the bypass to 15 percent, (3) 93 percent
control based upon improving the scrubber performance while
eliminating the bypass entirely, (this option results in a “wet
stack” operation in which the gas leaving the stack is saturated
with water) and (4) 93 percent as in option 3, with the addition of
an indirect reheat system to reheat the stack gas above the
saturation temperature. You must consider each of these four
options in a BART analysis for this source.
7. You are expected to identify potentially applicable retrofit
control technologies that represent the full range of demonstrated
alternatives. Examples of general information sources to consider
include:
• The EPA's Clean Air Technology Center, which includes the
RACT/BACT/LAER Clearinghouse (RBLC);
• State and Local Best Available Control Technology Guidelines -
many agencies have online information - for example South Coast Air
Quality Management District, Bay Area Air Quality Management
District, and Texas Natural Resources Conservation Commission;
• Control technology vendors;
• Federal/State/Local NSR permits and associated
inspection/performance test reports;
• Environmental consultants;
• Technical journals, reports and newsletters, air pollution
control seminars; and
• The EPA's NSR bulletin board -
http://www.epa.gov/ttn/nsr;
• Department of Energy's Clean Coal Program - technical
reports;
• The NOX Control Technology “Cost Tool” - Clean Air Markets
Division Web page -
http://www.epa.gov/airmarkets/arp/nox/controltech.html;
• Performance of selective catalytic reduction on coal-fired
steam generating units - final report. OAR/ARD, June 1997 (also
available at
http://www.epa.gov/airmarkets/arp/nox/controltech.html);
• Cost estimates for selected applications of NOX control
technologies on stationary combustion boilers. OAR/ARD June 1997.
(Docket for NOX SIP Call, A-96-56, item II-A-03);
• Investigation of performance and cost of NOX controls as
applied to group 2 boilers. OAR/ARD, August 1996. (Docket for Phase
II NOX rule, A-95-28, item IV-A-4);
• Controlling SO2 Emissions: A Review of Technologies.
EPA-600/R-00-093, USEPA/ORD/NRMRL, October 2000; and
• The OAQPS Control Cost Manual.
You are expected to compile appropriate information from these
information sources.
8. There may be situations where a specific set of units within
a fenceline constitutes the logical set to which controls would
apply and that set of units may or may not all be BART-eligible.
(For example, some units in that set may not have been constructed
between 1962 and 1977.)
9. If you find that a BART source has controls already in place
which are the most stringent controls available (note that this
means that all possible improvements to any control devices have
been made), then it is not necessary to comprehensively complete
each following step of the BART analysis in this section. As long
these most stringent controls available are made federally
enforceable for the purpose of implementing BART for that source,
you may skip the remaining analyses in this section, including the
visibility analysis in step 5. Likewise, if a source commits to a
BART determination that consists of the most stringent controls
available, then there is no need to complete the remaining analyses
in this section.
2. STEP 2: How do I determine whether the options identified in
Step 1 are technically feasible?
In Step 2, you evaluate the technical feasibility of the control
options you identified in Step 1. You should document a
demonstration of technical infeasibility and should explain, based
on physical, chemical, or engineering principles, why technical
difficulties would preclude the successful use of the control
option on the emissions unit under review. You may then eliminate
such technically infeasible control options from further
consideration in the BART analysis.
In general, what do we mean by technical feasibility?
Control technologies are technically feasible if either (1) they
have been installed and operated successfully for the type of
source under review under similar conditions, or (2) the technology
could be applied to the source under review. Two key concepts are
important in determining whether a technology could be applied:
“availability” and “applicability.” As explained in more detail
below, a technology is considered “available” if the source owner
may obtain it through commercial channels, or it is otherwise
available within the common sense meaning of the term. An available
technology is “applicable” if it can reasonably be installed and
operated on the source type under consideration. A technology that
is available and applicable is technically feasible.
What do we mean by “available” technology?
1. The typical stages for bringing a control technology concept
to reality as a commercial product are:
• Concept stage;
• Research and patenting;
• Bench scale or laboratory testing;
• Pilot scale testing;
• Licensing and commercial demonstration; and
• Commercial sales.
2. A control technique is considered available, within the
context presented above, if it has reached the stage of licensing
and commercial availability. Similarly, we do not expect a source
owner to conduct extended trials to learn how to apply a technology
on a totally new and dissimilar source type. Consequently, you
would not consider technologies in the pilot scale testing stages
of development as “available” for purposes of BART review.
3. Commercial availability by itself, however, is not
necessarily a sufficient basis for concluding a technology to be
applicable and therefore technically feasible. Technical
feasibility, as determined in Step 2, also means a control option
may reasonably be deployed on or “applicable” to the source type
under consideration.
Because a new technology may become available at various points
in time during the BART analysis process, we believe that
guidelines are needed on when a technology must be considered. For
example, a technology may become available during the public
comment period on the State's rule development process. Likewise,
it is possible that new technologies may become available after the
close of the State's public comment period and before submittal of
the SIP to EPA, or during EPA's review process on the SIP
submittal. In order to provide certainty in the process, all
technologies should be considered if available before the close of
the State's public comment period. You need not consider
technologies that become available after this date. As part of your
analysis, you should consider any technologies brought to your
attention in public comments. If you disagree with public comments
asserting that the technology is available, you should provide an
explanation for the public record as to the basis for your
conclusion.
What do we mean by “applicable” technology?
You need to exercise technical judgment in determining whether a
control alternative is applicable to the source type under
consideration. In general, a commercially available control option
will be presumed applicable if it has been used on the same or a
similar source type. Absent a showing of this type, you evaluate
technical feasibility by examining the physical and chemical
characteristics of the pollutant-bearing gas stream, and comparing
them to the gas stream characteristics of the source types to which
the technology had been applied previously. Deployment of the
control technology on a new or existing source with similar gas
stream characteristics is generally a sufficient basis for
concluding the technology is technically feasible barring a
demonstration to the contrary as described below.
What type of demonstration is required if I conclude that an option
is not technically feasible?
1. Where you conclude that a control option identified in Step 1
is technically infeasible, you should demonstrate that the option
is either commercially unavailable, or that specific circumstances
preclude its application to a particular emission unit. Generally,
such a demonstration involves an evaluation of the characteristics
of the pollutant-bearing gas stream and the capabilities of the
technology. Alternatively, a demonstration of technical
infeasibility may involve a showing that there are unresolvable
technical difficulties with applying the control to the source
(e.g., size of the unit, location of the proposed site, operating
problems related to specific circumstances of the source, space
constraints, reliability, and adverse side effects on the rest of
the facility). Where the resolution of technical difficulties is
merely a matter of increased cost, you should consider the
technology to be technically feasible. The cost of a control
alternative is considered later in the process.
2. The determination of technical feasibility is sometimes
influenced by recent air quality permits. In some cases, an air
quality permit may require a certain level of control, but the
level of control in a permit is not expected to be achieved in
practice (e.g., a source has received a permit but the project was
canceled, or every operating source at that permitted level has
been physically unable to achieve compliance with the limit). Where
this is the case, you should provide supporting documentation
showing why such limits are not technically feasible, and,
therefore, why the level of control (but not necessarily the
technology) may be eliminated from further consideration. However,
if there is a permit requiring the application of a certain
technology or emission limit to be achieved for such technology,
this usually is sufficient justification for you to assume the
technical feasibility of that technology or emission limit.
3. Physical modifications needed to resolve technical obstacles
do not, in and of themselves, provide a justification for
eliminating the control technique on the basis of technical
infeasibility. However, you may consider the cost of such
modifications in estimating costs. This, in turn, may form the
basis for eliminating a control technology (see later
discussion).
4. Vendor guarantees may provide an indication of commercial
availability and the technical feasibility of a control technique
and could contribute to a determination of technical feasibility or
technical infeasibility, depending on circumstances. However, we do
not consider a vendor guarantee alone to be sufficient
justification that a control option will work. Conversely, lack of
a vendor guarantee by itself does not present sufficient
justification that a control option or an emissions limit is
technically infeasible. Generally, you should make decisions about
technical feasibility based on chemical, and engineering analyses
(as discussed above), in conjunction with information about vendor
guarantees.
5. A possible outcome of the BART procedures discussed in these
guidelines is the evaluation of multiple control technology
alternatives which result in essentially equivalent emissions. It
is not our intent to encourage evaluation of unnecessarily large
numbers of control alternatives for every emissions unit.
Consequently, you should use judgment in deciding on those
alternatives for which you will conduct the detailed impacts
analysis (Step 4 below). For example, if two or more control
techniques result in control levels that are essentially identical,
considering the uncertainties of emissions factors and other
parameters pertinent to estimating performance, you may evaluate
only the less costly of these options. You should narrow the scope
of the BART analysis in this way only if there is a negligible
difference in emissions and energy and non-air quality
environmental impacts between control alternatives.
3. STEP 3: How do I evaluate technically feasible alternatives?
Step 3 involves evaluating the control effectiveness of all the
technically feasible control alternatives identified in Step 2 for
the pollutant and emissions unit under review.
Two key issues in this process include:
(1) Making sure that you express the degree of control using a
metric that ensures an “apples to apples” comparison of emissions
performance levels among options, and
(2) Giving appropriate treatment and consideration of control
techniques that can operate over a wide range of emission
performance levels.
What are the appropriate metrics for comparison?
This issue is especially important when you compare inherently
lower-polluting processes to one another or to add-on controls. In
such cases, it is generally most effective to express emissions
performance as an average steady state emissions level per unit of
product produced or processed.
Examples of common metrics:
• Pounds of SO2 emissions per million Btu heat input, and
• Pounds of NOX emissions per ton of cement produced.
How do I evaluate control techniques with a wide range of emission
performance levels?
1. Many control techniques, including both add-on controls and
inherently lower polluting processes, can perform at a wide range
of levels. Scrubbers and high and low efficiency electrostatic
precipitators (ESPs) are two of the many examples of such control
techniques that can perform at a wide range of levels. It is not
our intent to require analysis of each possible level of efficiency
for a control technique as such an analysis would result in a large
number of options. It is important, however, that in analyzing the
technology you take into account the most stringent emission
control level that the technology is capable of achieving. You
should consider recent regulatory decisions and performance data
(e.g., manufacturer's data, engineering estimates and the
experience of other sources) when identifying an emissions
performance level or levels to evaluate.
2. In assessing the capability of the control alternative,
latitude exists to consider special circumstances pertinent to the
specific source under review, or regarding the prior application of
the control alternative. However, you should explain the basis for
choosing the alternate level (or range) of control in the BART
analysis. Without a showing of differences between the source and
other sources that have achieved more stringent emissions limits,
you should conclude that the level being achieved by those other
sources is representative of the achievable level for the source
being analyzed.
3. You may encounter cases where you may wish to evaluate other
levels of control in addition to the most stringent level for a
given device. While you must consider the most stringent level as
one of the control options, you may consider less stringent levels
of control as additional options. This would be useful,
particularly in cases where the selection of additional options
would have widely varying costs and other impacts.
4. Finally, we note that for retrofitting existing sources in
addressing BART, you should consider ways to improve the
performance of existing control devices, particularly when a
control device is not achieving the level of control that other
similar sources are achieving in practice with the same device. For
example, you should consider requiring those sources with
electrostatic precipitators (ESPs) performing below currently
achievable levels to improve their performance.
4. STEP 4: For a BART review, what impacts am I expected to
calculate and report? What methods does EPA recommend for the
impacts analysis?
After you identify the available and technically feasible
control technology options, you are expected to conduct the
following analyses when you make a BART determination:
Impact analysis part 1: Costs of compliance,
Impact analysis part 2: Energy impacts, and
Impact analysis part 3: Non-air quality environmental
impacts.
Impact analysis part 4: Remaining useful life.
In this section, we describe how to conduct each of these three
analyses. You are responsible for presenting an evaluation of each
impact along with appropriate supporting information. You should
discuss and, where possible, quantify both beneficial and adverse
impacts. In general, the analysis should focus on the direct impact
of the control alternative. a. Impact analysis part 1: how do I
estimate the costs of control?
1. To conduct a cost analysis, you:
(1) Identify the emissions units being controlled,
(2) Identify design parameters for emission controls, and
(3) Develop cost estimates based upon those design
parameters.
2. It is important to identify clearly the emission units being
controlled, that is, to specify a well-defined area or process
segment within the plant. In some cases, multiple emission units
can be controlled jointly. However, in other cases, it may be
appropriate in the cost analysis to consider whether multiple units
will be required to install separate and/or different control
devices. The analysis should provide a clear summary list of
equipment and the associated control costs. Inadequate
documentation of the equipment whose emissions are being controlled
is a potential cause for confusion in comparison of costs of the
same controls applied to similar sources.
3. You then specify the control system design parameters.
Potential sources of these design parameters include equipment
vendors, background information documents used to support NSPS
development, control technique guidelines documents, cost manuals
developed by EPA, control data in trade publications, and
engineering and performance test data. The following are a few
examples of design parameters for two example control measures:
Control device |
Examples of design
parameters |
Wet Scrubbers |
Type of sorbent used (lime,
limestone, etc.).
Gas pressure drop.
Liquid/gas ratio. |
Selective
Catalytic Reduction |
Ammonia to NOX molar
ratio.
Pressure drop.
Catalyst life. |
4. The value selected for the design parameter should ensure
that the control option will achieve the level of emission control
being evaluated. You should include in your analysis documentation
of your assumptions regarding design parameters. Examples of
supporting references would include the EPA OAQPS Control Cost
Manual (see below) and background information documents used
for NSPS and hazardous pollutant emission standards. If the design
parameters you specified differ from typical designs, you should
document the difference by supplying performance test data for the
control technology in question applied to the same source or a
similar source.
5. Once the control technology alternatives and achievable
emissions performance levels have been identified, you then develop
estimates of capital and annual costs. The basis for equipment cost
estimates also should be documented, either with data supplied by
an equipment vendor (i.e., budget estimates or bids) or by a
referenced source (such as the OAQPS Control Cost Manual,
Fifth Edition, February 1996, EPA 453/B-96-001). 14 In order to
maintain and improve consistency, cost estimates should be based on
the OAQPS Control Cost Manual, where possible. 15 The
Control Cost Manual addresses most control technologies in
sufficient detail for a BART analysis. The cost analysis should
also take into account any site-specific design or other conditions
identified above that affect the cost of a particular BART
technology option.
14 The OAQPS Control Cost Manual is updated periodically.
While this citation refers to the latest version at the time this
guidance was written, you should use the version that is current as
of when you conduct your impact analysis. This document is
available at the following Web site:
http://www.epa.gov/ttn/catc/dir1/cs1ch2.pdf.
15 You should include documentation for any additional
information you used for the cost calculations, including any
information supplied by vendors that affects your assumptions
regarding purchased equipment costs, equipment life, replacement of
major components, and any other element of the calculation that
differs from the Control Cost Manual.
b. What do we mean by cost effectiveness?
Cost effectiveness, in general, is a criterion used to assess
the potential for achieving an objective in the most economical
way. For purposes of air pollutant analysis, “effectiveness” is
measured in terms of tons of pollutant emissions removed, and
“cost” is measured in terms of annualized control costs. We
recommend two types of cost-effectiveness calculations - average
cost effectiveness, and incremental cost effectiveness.
c. How do I calculate average cost effectiveness?
Average cost effectiveness means the total annualized costs of
control divided by annual emissions reductions (the difference
between baseline annual emissions and the estimate of emissions
after controls), using the following formula:
Average cost effectiveness (dollars per ton removed) =
Control
option annualized cost 16
16 Whenever you calculate or report annual costs, you should
indicate the year for which the costs are estimated. For example,
if you use the year 2000 as the basis for cost comparisons, you
would report that an annualized cost of $20 million would be: $20
million (year 2000 dollars).
Baseline annual emissions - Annual emissions with Control option
Because you calculate costs in (annualized) dollars per year
($/yr) and because you calculate emissions rates in tons per year
(tons/yr), the result is an average cost-effectiveness number in
(annualized) dollars per ton ($/ton) of pollutant removed.
d. How do I calculate baseline emissions?
1. The baseline emissions rate should represent a realistic
depiction of anticipated annual emissions for the source. In
general, for the existing sources subject to BART, you will
estimate the anticipated annual emissions based upon actual
emissions from a baseline period.
2. When you project that future operating parameters (e.g.,
limited hours of operation or capacity utilization, type of fuel,
raw materials or product mix or type) will differ from past
practice, and if this projection has a deciding effect in the BART
determination, then you must make these parameters or assumptions
into enforceable limitations. In the absence of enforceable
limitations, you calculate baseline emissions based upon
continuation of past practice.
3. For example, the baseline emissions calculation for an
emergency standby generator may consider the fact that the source
owner would not operate more than past practice of 2 weeks a year.
On the other hand, baseline emissions associated with a base-loaded
turbine should be based on its past practice which would indicate a
large number of hours of operation. This produces a significantly
higher level of baseline emissions than in the case of the
emergency/standby unit and results in more cost-effective controls.
As a consequence of the dissimilar baseline emissions, BART for the
two cases could be very different.
e. How do I calculate incremental cost effectiveness?
1. In addition to the average cost effectiveness of a control
option, you should also calculate incremental cost effectiveness.
You should consider the incremental cost effectiveness in
combination with the average cost effectiveness when considering
whether to eliminate a control option. The incremental cost
effectiveness calculation compares the costs and performance level
of a control option to those of the next most stringent option, as
shown in the following formula (with respect to cost per emissions
reduction):
Incremental Cost Effectiveness (dollars per incremental ton
removed) = (Total annualized costs of control option) − (Total
annualized costs of next control option) ÷ (Control option annual
emissions) − (Next control option annual emissions) Example
1:Assume that Option F on Figure 2 has total annualized costs of $1
million to reduce 2000 tons of a pollutant, and that Option D on
Figure 2 has total annualized costs of $500,000 to reduce 1000 tons
of the same pollutant. The incremental cost effectiveness of Option
F relative to Option D is ($1 million − $500,000) divided by (2000
tons − 1000 tons), or $500,000 divided by 1000 tons, which is
$500/ton. Example 2:Assume that two control options exist: Option 1
and Option 2. Option 1 achieves a 1,000 ton/yr reduction at an
annualized cost of $1,900,000. This represents an average cost of
($1,900,000/1,000 tons) = $1,900/ton. Option 2 achieves a 980
tons/yr reduction at an annualized cost of $1,500,000. This
represents an average cost of ($1,500,000/980 tons) = $1,531/ton.
The incremental cost effectiveness of Option 1 relative to Option 2
is ($1,900,000 − $1,500,000) divided by (1,000 tons − 980 tons).
The adoption of Option 1 instead of Option 2 results in an
incremental emission reduction of 20 tons per year at an additional
cost of $400,000 per year. The incremental cost of Option 1, then,
is $20,000 per ton − 11 times the average cost of $1,900 per ton.
While $1,900 per ton may still be deemed reasonable, it is useful
to consider both the average and incremental cost in making an
overall cost-effectiveness finding. Of course, there may be other
differences between these options, such as, energy or water use, or
non-air environmental effects, which also should be considered in
selecting a BART technology.
2. You should exercise care in deriving incremental costs of
candidate control options. Incremental cost-effectiveness
comparisons should focus on annualized cost and emission reduction
differences between “dominant” alternatives. To identify dominant
alternatives, you generate a graphical plot of total annualized
costs for total emissions reductions for all control alternatives
identified in the BART analysis, and by identifying a “least-cost
envelope” as shown in Figure 2. (A “least-cost envelope” represents
the set of options that should be dominant in the choice of a
specific option.)
Example:Eight technically feasible control options for analysis are
listed. These are represented as A through H in Figure 2. The
dominant set of control options, B, D, F, G, and H, represent the
least-cost envelope, as we depict by the cost curve connecting
them. Points A, C and E are inferior options, and you should not
use them in calculating incremental cost effectiveness. Points A, C
and E represent inferior controls because B will buy more emissions
reductions for less money than A; and similarly, D and F will buy
more reductions for less money than C and E, respectively.
3. In calculating incremental costs, you:
(1) Array the control options in ascending order of annualized
total costs,
(2) Develop a graph of the most reasonable smooth curve of the
control options, as shown in Figure 2. This is to show the
“least-cost envelope” discussed above; and
(3) Calculate the incremental cost effectiveness for each
dominant option, which is the difference in total annual costs
between that option and the next most stringent option, divided by
the difference in emissions, after controls have been applied,
between those two control options. For example, using Figure 2, you
would calculate incremental cost effectiveness for the difference
between options B and D, options D and F, options F and G, and
options G and H.
4. A comparison of incremental costs can also be useful in
evaluating the viability of a specific control option over a range
of efficiencies. For example, depending on the capital and
operational cost of a control device, total and incremental cost
may vary significantly (either increasing or decreasing) over the
operational range of a control device. Also, the greater the number
of possible control options that exist, the more weight should be
given to the incremental costs vs. average costs. It should be
noted that average and incremental cost effectiveness are identical
when only one candidate control option is known to exist.
5. You should exercise caution not to misuse these techniques.
For example, you may be faced with a choice between two available
control devices at a source, control A and control B, where control
B achieves slightly greater emission reductions. The average cost
(total annual cost/total annual emission reductions) for each may
be deemed to be reasonable. However, the incremental cost (total
annual costA - B/total annual emission reductionsA - B) of the
additional emission reductions to be achieved by control B may be
very great. In such an instance, it may be inappropriate to choose
control B, based on its high incremental costs, even though its
average cost may be considered reasonable.
6. In addition, when you evaluate the average or incremental
cost effectiveness of a control alternative, you should make
reasonable and supportable assumptions regarding control
efficiencies. An unrealistically low assessment of the emission
reduction potential of a certain technology could result in
inflated cost-effectiveness figures.
f. What other information should I provide in the cost impacts
analysis?
You should provide documentation of any unusual circumstances
that exist for the source that would lead to cost-effectiveness
estimates that would exceed that for recent retrofits. This is
especially important in cases where recent retrofits have
cost-effectiveness values that are within what has been considered
a reasonable range, but your analysis concludes that costs for the
source being analyzed are not considered reasonable. (A reasonable
range would be a range that is consistent with the range of cost
effectiveness values used in other similar permit decisions over a
period of time.)
Example:In an arid region, large amounts of water are needed for a
scrubbing system. Acquiring water from a distant location could
greatly increase the cost per ton of emissions reduced of wet
scrubbing as a control option. g. What other things are important
to consider in the cost impacts analysis?
In the cost analysis, you should take care not to focus on
incomplete results or partial calculations. For example, large
capital costs for a control option alone would not preclude
selection of a control measure if large emissions reductions are
projected. In such a case, low or reasonable cost effectiveness
numbers may validate the option as an appropriate BART alternative
irrespective of the large capital costs. Similarly, projects with
relatively low capital costs may not be cost effective if there are
few emissions reduced.
h. Impact analysis part 2: How should I analyze and report energy
impacts?
1. You should examine the energy requirements of the control
technology and determine whether the use of that technology results
in energy penalties or benefits. A source owner may, for example,
benefit from the combustion of a concentrated gas stream rich in
volatile organic compounds; on the other hand, more often extra
fuel or electricity is 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 practicable. Because
energy penalties or benefits can usually be quantified in terms of
additional cost or income to the source, the energy impacts
analysis can, in most cases, simply be factored into the cost
impacts analysis. The fact of energy use in and of itself does not
disqualify a technology.
2. Your energy impact analysis should consider only direct
energy consumption and not indirect energy impacts. For example,
you 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 should be shown in terms of total (and in
certain cases, also incremental) energy costs per ton of pollutant
removed. You can then convert these units into dollar costs and,
where appropriate, factor these costs into the control cost
analysis.
3. You generally do not consider indirect energy impacts (such
as energy to produce raw materials for construction of control
equipment). However, if you determine, either independently or
based on a showing by the source owner, that the indirect energy
impact is unusual or significant and that the impact can be well
quantified, you may consider the indirect impact.
4. The energy impact analysis may also address concerns over the
use of locally scarce fuels. The designation of a scarce fuel may
vary from region to region. However, 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.
5. Finally, the energy impacts analysis may consider whether
there are relative differences between alternatives regarding the
use of locally or regionally available coal, and whether a given
alternative would result in significant economic disruption or
unemployment. For example, where two options are equally cost
effective and achieve equivalent or similar emissions reductions,
one option may be preferred if the other alternative results in
significant disruption or unemployment.
i. Impact analysis part 3: How do I analyze “non-air quality
environmental impacts?”
1. In the non-air quality related environmental impacts portion
of the BART analysis, you address environmental impacts other than
air quality due to emissions of the pollutant in question. Such
environmental impacts include solid or hazardous waste generation
and discharges of polluted water from a control device.
2. You should identify any significant or unusual environmental
impacts associated with a control alternative that have the
potential to affect the selection or elimination of a control
alternative. Some control technologies may have potentially
significant secondary environmental impacts. Scrubber effluent, for
example, may affect water quality and land use. Alternatively,
water availability may affect the feasibility and costs of wet
scrubbers. 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 reductions potential of the
more stringent control is only marginally greater than the next
most-effective option. However, the fact that a control device
creates liquid and solid waste that must be disposed of does not
necessarily argue against selection of that technology as BART,
particularly if the control device has been applied to similar
facilities elsewhere and the solid or liquid waste is similar to
those other applications. On the other hand, where you or the
source owner can show that unusual circumstances at the proposed
facility create greater problems than experienced elsewhere, this
may provide a basis for the elimination of that control alternative
as BART.
3. The procedure for conducting an analysis of non-air quality
environmental impacts should be made based on a consideration of
site-specific circumstances. If you propose to adopt the most
stringent alternative, then it is not necessary to perform this
analysis of environmental impacts for the entire list of
technologies you ranked in Step 3. In general, the analysis need
only address those control alternatives with any significant or
unusual environmental impacts that have the potential to affect the
selection of a control alternative, or elimination of a more
stringent control alternative. Thus, any important relative
environmental impacts (both positive and negative) of alternatives
can be compared with each other.
4. In general, the analysis of impacts starts with the
identification and quantification of the solid, liquid, and gaseous
discharges from the control device or devices under review.
Initially, you should perform a qualitative or semi-quantitative
screening to narrow the analysis to discharges with potential for
causing adverse environmental effects. Next, you should assess the
mass and composition of any such discharges and quantify them to
the extent possible, based on readily available information. You
should also assemble pertinent information about the public or
environmental consequences of releasing these materials.
j. Impact analysis part 4: What are examples of non-air quality
environmental impacts?
The following are examples of how to conduct non-air quality
environmental impacts:
(1) Water Impact
You should identify the relative quantities of water used and
water pollutants produced and discharged as a result of the use of
each alternative emission control system. Where possible, you
should assess the effect on ground water and such local surface
water quality parameters as ph, turbidity, dissolved oxygen,
salinity, toxic chemical levels, temperature, and any other
important considerations. The analysis could consider whether
applicable water quality standards will be met and the availability
and effectiveness of various techniques to reduce potential adverse
effects.
(2) Solid Waste Disposal Impact
You could also compare the quality and quantity of solid waste
(e.g., sludges, solids) that must be stored and disposed of or
recycled as a result of the application of each alternative
emission control system. You should consider the composition and
various other characteristics of the solid waste (such as
permeability, water retention, rewatering of dried material,
compression strength, leachability of dissolved ions, bulk density,
ability to support vegetation growth and hazardous characteristics)
which are significant with regard to potential surface water
pollution or transport into and contamination of subsurface waters
or aquifers.
(3) Irreversible or Irretrievable Commitment of
Resources
You may consider the extent to which the alternative emission
control systems may involve a trade-off between short-term
environmental gains at the expense of long-term environmental
losses and the extent to which the alternative systems may result
in irreversible or irretrievable commitment of resources (for
example, use of scarce water resources).
(4) Other Adverse Environmental Impacts
You may consider significant differences in noise levels,
radiant heat, or dissipated static electrical energy of pollution
control alternatives. Other examples of non-air quality
environmental impacts would include hazardous waste discharges such
as spent catalysts or contaminated carbon.
k. How do I take into account a project's “remaining useful life”
in calculating control costs?
1. You may decide to treat the requirement to consider the
source's “remaining useful life” of the source for BART
determinations as one element of the overall cost analysis. The
“remaining useful life” of a source, if it represents a relatively
short time period, may affect the annualized costs of retrofit
controls. For example, the methods for calculating annualized costs
in EPA's OAQPS Control Cost Manual require the use of a
specified time period for amortization that varies based upon the
type of control. If the remaining useful life will clearly exceed
this time period, the remaining useful life has essentially no
effect on control costs and on the BART determination process.
Where the remaining useful life is less than the time period for
amortizing costs, you should use this shorter time period in your
cost calculations.
2. For purposes of these guidelines, the remaining useful life
is the difference between:
(1) The date that controls will be put in place (capital and
other construction costs incurred before controls are put in place
can be rolled into the first year, as suggested in EPA's OAQPS
Control Cost Manual); you are conducting the BART analysis;
and
(2) The date the facility permanently stops operations. Where
this affects the BART determination, this date should be assured by
a federally- or State-enforceable restriction preventing further
operation.
3. We recognize that there may be situations where a source
operator intends to shut down a source by a given date, but wishes
to retain the flexibility to continue operating beyond that date in
the event, for example, that market conditions change. Where this
is the case, your BART analysis may account for this, but it must
maintain consistency with the statutory requirement to install BART
within 5 years. Where the source chooses not to accept a federally
enforceable condition requiring the source to shut down by a given
date, it is necessary to determine whether a reduced time period
for the remaining useful life changes the level of controls that
would have been required as BART.
If the reduced time period does change the level of BART
controls, you may identify, and include as part of the BART
emission limitation, the more stringent level of control that would
be required as BART if there were no assumption that reduced the
remaining useful life. You may incorporate into the BART emission
limit this more stringent level, which would serve as a contingency
should the source continue operating more than 5 years after the
date EPA approves the relevant SIP. The source would not be allowed
to operate after the 5-year mark without such controls. If a source
does operate after the 5-year mark without BART in place, the
source is considered to be in violation of the BART emissions limit
for each day of operation.
5. Step 5: How should I determine visibility impacts in the BART
determination?
The following is an approach you may use to determine visibility
impacts (the degree of visibility improvement for each source
subject to BART) for the BART determination. Once you have
determined that your source or sources are subject to BART, you
must conduct a visibility improvement determination for the
source(s) as part of the BART determination. When making this
determination, we believe you have flexibility in setting absolute
thresholds, target levels of improvement, or de minimis
levels since the deciview improvement must be weighed among the
five factors, and you are free to determine the weight and
significance to be assigned to each factor. For example, a 0.3
deciview improvement may merit a stronger weighting in one case
versus another, so one “bright line” may not be appropriate. [Note
that if sources have elected to apply the most stringent controls
available, consistent with the discussion in section E. step 1.
below, you need not conduct, or require the source to conduct, an
air quality modeling analysis for the purpose of determining its
visibility impacts.]
Use CALPUFF, 17 or other appropriate dispersion model to
determine the visibility improvement expected at a Class I area
from the potential BART control technology applied to the source.
Modeling should be conducted for SO2, NOX, and direct PM emissions
(PM2.5 and/or PM10). If the source is making the visibility
determination, you should review and approve or disapprove of the
source's analysis before making the expected improvement
determination. There are several steps for determining the
visibility impacts from an individual source using a dispersion
model:
17 The model code and its documentation are available at no cost
for download from
http://www.epa.gov/scram001/tt22.htm#calpuff.
• Develop a modeling protocol.
Some critical items to include in a modeling protocol are
meteorological and terrain data, as well as source-specific
information (stack height, temperature, exit velocity, elevation,
and allowable and actual emission rates of applicable pollutants),
and receptor data from appropriate Class I areas. We recommend
following EPA's Interagency Workgroup on Air Quality Modeling
(IWAQM) Phase 2 Summary Report and Recommendations for Modeling
Long Range Transport Impacts 18 for parameter settings and
meteorological data inputs; the use of other settings from those in
IWAQM should be identified and explained in the protocol.
18 Interagency Workgroup on Air Quality Modeling (IWAQM)
Phase 2 Summary Report and Recommendations for Modeling Long Range
Transport Impacts, U.S. Environmental Protection Agency,
EPA-454/R-98-019, December 1998.
One important element of the protocol is in establishing the
receptors that will be used in the model. The receptors that you
use should be located in the nearest Class I area with sufficient
density to identify the likely visibility effects of the source.
For other Class I areas in relatively close proximity to a
BART-eligible source, you may model a few strategic receptors to
determine whether effects at those areas may be greater than at the
nearest Class I area. For example, you might chose to locate
receptors at these areas at the closest point to the source, at the
highest and lowest elevation in the Class I area, at the IMPROVE
monitor, and at the approximate expected plume release height. If
the highest modeled effects are observed at the nearest Class I
area, you may choose not to analyze the other Class I areas any
further as additional analyses might be unwarranted.
You should bear in mind that some receptors within the relevant
Class I area may be less than 50 km from the source while other
receptors within that same Class I area may be greater than 50 km
from the same source. As indicated by the Guideline on Air
Quality Models, this situation may call for the use of two
different modeling approaches for the same Class I area and source,
depending upon the State's chosen method for modeling sources less
than 50 km. In situations where you are assessing visibility
impacts for source-receptor distances less than 50 km, you should
use expert modeling judgment in determining visibility impacts,
giving consideration to both CALPUFF and other EPA-approved
methods.
In developing your modeling protocol, you may want to consult
with EPA and your regional planning organization (RPO). Up-front
consultation will ensure that key technical issues are addressed
before you conduct your modeling.
• For each source, run the model, at pre-control and
post-control emission rates according to the accepted methodology
in the protocol.
Use the 24-hour average actual emission rate from the highest
emitting day of the meteorological period modeled (for the
pre-control scenario). Calculate the model results for each
receptor as the change in deciviews compared against natural
visibility conditions. Post-control emission rates are calculated
as a percentage of pre-control emission rates. For example, if the
24-hr pre-control emission rate is 100 lb/hr of SO2, then the post
control rate is 5 lb/hr if the control efficiency being evaluated
is 95 percent.
• Make the net visibility improvement determination.
Assess the visibility improvement based on the modeled change in
visibility impacts for the pre-control and post-control emission
scenarios. You have flexibility to assess visibility improvements
due to BART controls by one or more methods. You may consider the
frequency, magnitude, and duration components of impairment.
Suggestions for making the determination are:
• Use of a comparison threshold, as is done for determining if
BART-eligible sources should be subject to a BART determination.
Comparison thresholds can be used in a number of ways in evaluating
visibility improvement (e.g., the number of days or hours that the
threshold was exceeded, a single threshold for determining whether
a change in impacts is significant, or a threshold representing an
x percent change in improvement).
• Compare the 98th percent days for the pre- and post-control
runs.
Note that each of the modeling options may be supplemented with
source apportionment data or source apportionment modeling.
E. How do I select the “best” alternative, using the results of
Steps 1 through 5? 1. Summary of the Impacts Analysis
From the alternatives you evaluated in Step 3, we recommend you
develop a chart (or charts) displaying for each of the
alternatives:
(1) Expected emission rate (tons per year, pounds per hour);
(2) Emissions performance level (e.g., percent pollutant
removed, emissions per unit product, lb/MMBtu, ppm);
(3) Expected emissions reductions (tons per year);
(4) Costs of compliance - total annualized costs ($), cost
effectiveness ($/ton), and incremental cost effectiveness ($/ton),
and/or any other cost-effectiveness measures (such as
$/deciview);
(5) Energy impacts;
(6) Non-air quality environmental impacts; and
(7) Modeled visibility impacts.
2. Selecting a “best” alternative
1. You have discretion to determine the order in which you
should evaluate control options for BART. Whatever the order in
which you choose to evaluate options, you should always (1) display
the options evaluated; (2) identify the average and incremental
costs of each option; (3) consider the energy and non-air quality
environmental impacts of each option; (4) consider the remaining
useful life; and (5) consider the modeled visibility impacts. You
should provide a justification for adopting the technology that you
select as the “best” level of control, including an explanation of
the CAA factors that led you to choose that option over other
control levels.
2. In the case where you are conducting a BART determination for
two regulated pollutants on the same source, if the result is two
different BART technologies that do not work well together, you
could then substitute a different technology or combination of
technologies.
3. In selecting a “best” alternative, should I consider the
affordability of controls?
1. Even if the control technology is cost effective, there may
be cases where the installation of controls would affect the
viability of continued plant operations.
2. There may be unusual circumstances that justify taking into
consideration the conditions of the plant and the economic effects
of requiring the use of a given control technology. These effects
would include effects on product prices, the market share, and
profitability of the source. Where there are such unusual
circumstances that are judged to affect plant operations, you may
take into consideration the conditions of the plant and the
economic effects of requiring the use of a control technology.
Where these effects are judged to have a severe impact on plant
operations you may consider them in the selection process, but you
may wish to provide an economic analysis that demonstrates, in
sufficient detail for public review, the specific economic effects,
parameters, and reasoning. (We recognize that this review process
must preserve the confidentiality of sensitive business
information). Any analysis may also consider whether other
competing plants in the same industry have been required to install
BART controls if this information is available.
4. Sulfur dioxide limits for utility boilers
You must require 750 MW power plants to meet specific control
levels for SO2 of either 95 percent control or 0.15 lbs/MMBtu, for
each EGU greater than 200 MW that is currently uncontrolled unless
you determine that an alternative control level is justified based
on a careful consideration of the statutory factors. Thus, for
example, if the source demonstrates circumstances affecting its
ability to cost-effectively reduce its emissions, you should take
that into account in determining whether the presumptive levels of
control are appropriate for that facility. For a currently
uncontrolled EGU greater than 200 MW in size, but located at a
power plant smaller than 750 MW in size, such controls are
generally cost-effective and could be used in your BART
determination considering the five factors specified in CAA section
169A(g)(2). While these levels may represent current control
capabilities, we expect that scrubber technology will continue to
improve and control costs continue to decline. You should be sure
to consider the level of control that is currently best achievable
at the time that you are conducting your BART analysis.
For coal-fired EGUs with existing post-combustion SO2 controls
achieving less than 50 percent removal efficiencies, we recommend
that you evaluate constructing a new FGD system to meet the same
emission limits as above (95 percent removal or 0.15 lb/mmBtu), in
addition to the evaluation of scrubber upgrades discussed below.
For oil-fired units, regardless of size, you should evaluate
limiting the sulfur content of the fuel oil burned to 1 percent or
less by weight.
For those BART-eligible EGUs with pre-existing post-combustion
SO2 controls achieving removal efficiencies of at least 50 percent,
your BART determination should consider cost effective scrubber
upgrades designed to improve the system's overall SO2 removal
efficiency. There are numerous scrubber enhancements available to
upgrade the average removal efficiencies of all types of existing
scrubber systems. We recommend that as you evaluate the definition
of “upgrade,” you evaluate options that not only improve the design
removal efficiency of the scrubber vessel itself, but also consider
upgrades that can improve the overall SO2 removal efficiency of the
scrubber system. Increasing a scrubber system's reliability, and
conversely decreasing its downtime, by way of optimizing operation
procedures, improving maintenance practices, adjusting scrubber
chemistry, and increasing auxiliary equipment redundancy, are all
ways to improve average SO2 removal efficiencies.
We recommend that as you evaluate the performance of existing
wet scrubber systems, you consider some of the following upgrades,
in no particular order, as potential scrubber upgrades that have
been proven in the industry as cost effective means to increase
overall SO2 removal of wet systems:
(a) Elimination of Bypass Reheat;
(b) Installation of Liquid Distribution Rings;
(c) Installation of Perforated Trays;
(d) Use of Organic Acid Additives;
(e) Improve or Upgrade Scrubber Auxiliary System Equipment;
(f) Redesign Spray Header or Nozzle Configuration.
We recommend that as you evaluate upgrade options for dry
scrubber systems, you should consider the following cost effective
upgrades, in no particular order:
(a) Use of Performance Additives;
(b) Use of more Reactive Sorbent;
(c) Increase the Pulverization Level of Sorbent;
(d) Engineering redesign of atomizer or slurry injection
system.
You should evaluate scrubber upgrade options based on the 5 step
BART analysis process.
5. Nitrogen oxide limits for utility boilers
You should establish specific numerical limits for NOX control
for each BART determination. For power plants with a generating
capacity in excess of 750 MW currently using selective catalytic
reduction (SCR) or selective non-catalytic reduction (SNCR) for
part of the year, you should presume that use of those same
controls year-round is BART. For other sources currently using SCR
or SNCR to reduce NOX emissions during part of the year, you should
carefully consider requiring the use of these controls year-round
as the additional costs of operating the equipment throughout the
year would be relatively modest.
For coal-fired EGUs greater than 200 MW located at greater than
750 MW power plants and operating without post-combustion controls
(i.e. SCR or SNCR), we have provided presumptive NOX limits,
differentiated by boiler design and type of coal burned. You may
determine that an alternative control level is appropriate based on
a careful consideration of the statutory factors. For coal-fired
EGUs greater than 200 MW located at power plants 750 MW or less in
size and operating without post-combustion controls, you should
likewise presume that these same levels are cost-effective. You
should require such utility boilers to meet the following NOX
emission limits, unless you determine that an alternative control
level is justified based on consideration of the statutory factors.
The following NOX emission rates were determined based on a number
of assumptions, including that the EGU boiler has enough volume to
allow for installation and effective operation of separated
overfire air ports. For boilers where these assumptions are
incorrect, these emission limits may not be cost-effective.
Table 1 - Presumptive NOX Emission Limits
for BART-Eligible Coal-Fired Units. 19
Unit type |
Coal type |
NOX presumptive limit
(lb/mmbtu) 20 |
Dry-bottom
wall-fired |
Bituminous |
0.39 |
|
Sub-bituminous |
0.23 |
|
Lignite |
0.29 |
Tangential-fired |
Bituminous |
0.28 |
|
Sub-bituminous |
0.15 |
|
Lignite |
0.17 |
Cell Burners |
Bituminous |
0.40 |
|
Sub-bituminous |
0.45 |
Dry-turbo-fired |
Bituminous |
0.32 |
|
Sub-bituminous |
0.23 |
Wet-bottom
tangential-fired |
Bituminous |
0.62 |
Most EGUs can meet these presumptive NOX limits through the use
of current combustion control technology, i.e. the careful
control of combustion air and low-NOX burners. For units that
cannot meet these limits using such technologies, you should
consider whether advanced combustion control technologies such as
rotating opposed fire air should be used to meet these limits.
Because of the relatively high NOX emission rates of cyclone
units, SCR is more cost-effective than the use of current
combustion control technology for these units. The use of SCRs at
cyclone units burning bituminous coal, sub-bituminous coal, and
lignite should enable the units to cost-effectively meet NOX rates
of 0.10 lbs/mmbtu. As a result, we are establishing a presumptive
NOX limit of 0.10 lbs/mmbtu based on the use of SCR for coal-fired
cyclone units greater than 200 MW located at 750 MW power plants.
As with the other presumptive limits established in this guideline,
you may determine that an alternative level of control is
appropriate based on your consideration of the relevant statutory
factors. For other cyclone units, you should review the use of SCR
and consider whether these post-combustion controls should be
required as BART.
For oil-fired and gas-fired EGUs larger than 200MW, we believe
that installation of current combustion control technology to
control NOX is generally highly cost-effective and should be
considered in your determination of BART for these sources. Many
such units can make significant reductions in NOX emissions which
are highly cost-effective through the application of current
combustion control technology. 21
21 See Technical Support Document for BART NOX Limits
for Electric Generating Units and Technical Support Document
for BART NOX Limits for Electric Generating Units Excel
Spreadsheet, Memorandum to Docket OAR 2002-0076, April 15,
2005.
V. Enforceable Limits/Compliance Date
To complete the BART process, you must establish enforceable
emission limits that reflect the BART requirements and require
compliance within a given period of time. In particular, you must
establish an enforceable emission limit for each subject emission
unit at the source and for each pollutant subject to review that is
emitted from the source. In addition, you must require compliance
with the BART emission limitations no later than 5 years after EPA
approves your regional haze SIP. If technological or economic
limitations in the application of a measurement methodology to a
particular emission unit make a conventional emissions limit
infeasible, you may instead prescribe a design, equipment, work
practice, operation standard, or combination of these types of
standards. You should consider allowing sources to “average”
emissions across any set of BART-eligible emission units within a
fenceline, so long as the emission reductions from each pollutant
being controlled for BART would be equal to those reductions that
would be obtained by simply controlling each of the BART-eligible
units that constitute BART-eligible source.
You should ensure that any BART requirements are written in a
way that clearly specifies the individual emission unit(s) subject
to BART regulation. Because the BART requirements themselves are
“applicable” requirements of the CAA, they must be included as
title V permit conditions according to the procedures established
in 40 CFR part 70 or 40 CFR part 71.
Section 302(k) of the CAA requires emissions limits such as BART
to be met on a continuous basis. Although this provision does not
necessarily require the use of continuous emissions monitoring
(CEMs), it is important that sources employ techniques that ensure
compliance on a continuous basis. Monitoring requirements generally
applicable to sources, including those that are subject to BART,
are governed by other regulations. See, e.g., 40 CFR part 64
(compliance assurance monitoring); 40 CFR 70.6(a)(3) (periodic
monitoring); 40 CFR 70.6(c)(1) (sufficiency monitoring). Note also
that while we do not believe that CEMs would necessarily be
required for all BART sources, the vast majority of electric
generating units potentially subject to BART already employ CEM
technology for other programs, such as the acid rain program. In
addition, emissions limits must be enforceable as a practical
matter (contain appropriate averaging times, compliance
verification procedures and recordkeeping requirements). In light
of the above, the permit must:
• Be sufficient to show compliance or noncompliance
(i.e., through monitoring times of operation, fuel input, or
other indices of operating conditions and practices); and
• Specify a reasonable averaging time consistent with
established reference methods, contain reference methods for
determining compliance, and provide for adequate reporting and
recordkeeping so that air quality agency personnel can determine
the compliance status of the source; and
• For EGUS, specify an averaging time of a 30-day rolling
average, and contain a definition of “boiler operating day” that is
consistent with the definition in the proposed revisions to the
NSPS for utility boilers in 40 CFR Part 60, subpart Da. 22 You
should consider a boiler operating day to be any 24-hour period
between 12:00 midnight and the following midnight during which any
fuel is combusted at any time at the steam generating unit. This
would allow 30-day rolling average emission rates to be calculated
consistently across sources.
22 70 FR 9705, February 28, 2005.
[70 FR 39156, July 6, 2005]