39104 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 51 

[FRL–7925–9] 

RIN 2060–AJ31 

Regional Haze Regulations and 

Guidelines for Best Available Retrofit 

Technology (BART) Determinations

AGENCY: Environmental Protection 

Agency (EPA).

ACTION: Final rule.

SUMMARY: On July 1, 1999, EPA 

promulgated regulations to address 

regional haze (64 FR 35714). These 

regulations were challenged, and on 

May 24, 2002, the U.S. Court of Appeals 

for the District of Columbia Circuit 

issued a ruling vacating the regional 

haze rule in part and sustaining it in 

part. American Corn Growers Ass’n v. 

EPA, 291 F.3d 1 (D.C. Cir. 2002). 

Today’s rule addresses the court’s ruling 

in that case. 

In addition, prior to the court’s 

decision, EPA had proposed guidelines 

for implementation of the Best Available 

Retrofit Technology (BART) 

requirements under the regional haze 

rule, (66 FR 38108, July 20, 2001). The 

proposed guidelines were intended to 

clarify the requirements of the regional 

haze rule’s BART provisions. We 

proposed to add the guidelines and also 

proposed to add regulatory text 

requiring that these guidelines be used 

for addressing BART determinations 

under the regional haze rule. In 

addition, we proposed one revision to 

guidelines issued in 1980 for facilities 

contributing to ‘‘reasonably 

attributable’’ visibility impairment. 

In the American Corn Growers case, 

the court vacated and remanded the 

BART provisions of the regional haze 

rule. In response to the court’s ruling, 

on May 5, 2004 we proposed new BART 

provisions and reproposed the BART 

guidelines. The American Corn Growers

court also remanded to the Agency its 

decision to extend the deadline for the 

submittal of regional haze plans. 

Subsequently, Congress amended the 

deadlines for regional haze plans 

(Consolidated Appropriations Act for 

Fiscal Year 2004, Public Law 108–199, 

January 23, 2004). The May 5, 2004 

proposed rule also contained an 

amendment to the regional haze rule to 

conform to the new statutory deadlines. 

We received numerous comments on 

both the July 20, 2001 proposal and the 

May 5, 2004 reproposal. Today’s final 

rule reflects our review of the public 

comments.

DATES: The regulatory amendments 

announced herein take effect on 

September 6, 2005.

ADDRESSES: Docket. All documents in 

the docket are listed in the EDOCKET 

index at http://www.epa.gov/edocket.

Although listed in the index, some 

information is not publicly available, 

i.e., CBI or other information whose 

disclosure is restricted by statute. 

Certain other material, such as 

copyrighted material, is not placed on 

the Internet and will be publicly 

available only in hard copy form. 

Publicly available docket materials are 

available either electronically in 

EDOCKET or in hard copy at the OAR 

Docket, EPA/DC, EPA West, Room 

B102, 1301 Constitution Ave., NW., 

Washington, DC. The Public Reading 

Room is open from 8:30 a.m. to 4:30 

p.m., Monday through Friday, excluding 

legal holidays. The telephone number 

for the Public Reading Room is (202) 

566–1744, and the telephone number for 

the OAR Docket is (202) 566–1742.

FOR FURTHER INFORMATION CONTACT:

Kathy Kaufman at (919) 541–0102 or by 

e-mail at Kaufman.Kathy@epa.gov or 

Todd Hawes at 919–541–5591 or by email Hawes.Todd@epa.gov.

SUPPLEMENTARY INFORMATION: 

Regulated Entities. This final rule will 

affect the following: State and local 

permitting authorities and Indian Tribes 

containing major stationary sources of 

pollution affecting visibility in federally 

protected scenic areas. 

This list is not intended to be 

exhaustive, but rather provides a guide 

for readers regarding entities likely to be 

regulated by this action. This list gives 

examples of the types of entities EPA is 

now aware could potentially be 

regulated by this action. Other types of 

entities not listed could also be affected. 

To determine whether your facility, 

company, business, organization, etc., is 

regulated by this action, you should 

examine the applicability criteria in Part 

II of this preamble. If you have any 

questions regarding the applicability of 

this action to a particular entity, consult 

the people listed in the preceding 

section. 

Outline. The contents of today’s 

preamble are listed in the following 

outline.

I. Overview of Today’s Proposed Actions 

II. Background 

A. Regional Haze Rule 

B. Partial Remand of the Regional Haze 

Rule in American Corn Growers

C. Changes in Response to American Corn 

Growers

D. Center for Energy and Economic 

Development v. EPA

E. Relationship Between BART and the 

Clean Air Interstate Rule (CAIR) 

F. Overview of the BART Process 

III. Detailed Discussion of the BART 

Guidelines 

A. Introduction 

B. Scope of the Rule—Whether to Require 

States to Follow the Guidelines for All 

BART Sources 

C. How to Identify BART-Eligible Sources 

D. How to Determine Which BART-Eligible 

Sources are Subject to BART 

E. The BART Determination Process 

IV. Effect of This Rule on State Options for 

Using Alternative Strategies In Lieu of 

Source-by-Source BART 

V. Statutory and Executive Order Reviews 

A. Executive Order 12866: Regulatory 

Planning and Review 

B. Paperwork Reduction Act 

C. Regulatory Flexibility Act 

D. Unfunded Mandates Reform Act 

E. Executive Order 13132: Federalism 

F. Executive Order 13175: Consultation 

and Coordination with Indian Tribal 

Governments

G. Executive Order 13045: Protection of 

Children from Environmental Health 

Risks and Safety Risks 

H. Executive Order 13211: Actions That 

Significantly Affect Energy Supply, 

Distribution, or Use. 

I. National Technology Transfer 

Advancement Act 

J. Executive Order 12898: Federal Actions 

to Address Environmental Justice in 

Minority Populations and Low-Income 

Populations

I. Overview of Today’s Actions 

Today’s rulemaking provides the 

following changes to the regional haze 

regulations: 

(1) Revised regulatory text in response 

to the American Corn Growers court’s 

remand, to require that the BART 

determination include an analysis of the 

degree of visibility improvement 

resulting from the use of control 

technology at each source subject to 

BART, 

(2) Revised regulatory text in 40 CFR 

51.308(b) and deletion of 40 CFR 

51.308(c) Options for regional planning

in response to Congressional legislation 

amending the deadlines for submittal of 

regional haze implementation plans. 

This provision had provided for an 

alternative process for States to submit 

regional haze implementation plans in 

attainment areas, 

(3) BART guidelines, contained in a 

new Appendix Y to 40 CFR part 51, 

(4) New and revised regulatory text, to 

be added to 40 CFR 51.308(e), regarding 

the use of Appendix Y in establishing 

BART emission limits, and 

(5) Revised regulatory language at 40 

CFR 51.302 to clarify the relationship 

between New Source Performance 

Standards (NSPS) and BART for 

reasonably attributable visibility 

impairment. 

How This Preamble Is Structured.

Section II provides background on the 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39105

1See, e.g. CAA Section 169A(a)(1).

2American Corn Growers et al. v. EPA, 291 F.3d 

1 (2002).

3CAA sections 169A(b)(2) and (g)(7).

4See 66 FR at 35737–35743 for a discussion of 

the rationale for the BART requirements in the 1999 

regional haze rule.

Clean Air Act (CAA) BART 

requirements as codified in the regional 

haze rule, on the D.C. Circuit Court 

decision which remanded parts of the 

rule, and on the April 2004 reproposal 

responding to the remand. Section III 

discusses specific issues in the BART 

guidelines in more detail, including 

background on each issue, major 

comments we received on the July 2001 

proposal and May 2004 reproposal, and 

our responses to those comments. 

Section IV provides a discussion of how 

this rulemaking complies with the 

requirements of Statutory and Executive 

Order Reviews. 

II. Background 

A. The Regional Haze Rule 

In 1999, we published a final rule to 

address a type of visibility impairment 

known as regional haze (64 FR 35714, 

July 1, 1999). The regional haze rule 

requires States to submit 

implementation plans (SIPs) to address 

regional haze visibility impairment in 

156 Federally-protected parks and 

wilderness areas. These 156 scenic areas 

are called ‘‘mandatory Class I Federal 

areas’’ in the Clean Air Act (CAA)1 but 

are referred to simply as ‘‘Class I areas’’

in today’s rulemaking. The 1999 rule 

was issued to fulfill a long-standing EPA 

commitment to address regional haze 

under the authority and requirements of 

sections 169A and 169B of the CAA.

As required by the CAA, we included 

in the final regional haze rule a 

requirement for BART for certain large 

stationary sources that were put in place 

between 1962 and 1977. We discussed 

these requirements in detail in the 

preamble to the final rule (64 FR at 

35737–35743). The regulatory 

requirements for BART were codified at 

40 CFR 51.308(e) and in definitions that 

appear in 40 CFR 51.301. 

The CAA, in sections 169A(b)(2)(A) 

and in 169A(g)(7), uses the term ‘‘major 

stationary source’’ to describe those 

sources that are the focus of the BART 

requirement. To avoid confusion with 

other CAA requirements which also use 

the term ‘‘major stationary source’’ to 

refer to a somewhat different population 

of sources, the regional haze rule uses 

the term ‘‘BART-eligible source’’ to 

describe these sources. The BARTeligible sources are those sources which 

have the potential to emit 250 tons or 

more of a visibility-impairing air 

pollutant, were put in place between 

August 7, 1962 and August 7, 1977, and 

whose operations fall within one or 

more of 26 specifically listed source 

categories. Under the CAA, BART is 

required for any BART-eligible source 

which a State determines ‘‘emits any air 

pollutant which may reasonably be 

anticipated to cause or contribute to any 

impairment of visibility in any such 

area.’’ Accordingly, for stationary 

sources meeting these criteria, States 

must address the BART requirement 

when they develop their regional haze 

SIPs. 

Section 169A(g)(7) of the CAA 

requires that States must consider the 

following factors in making BART 

determinations: 

(1) The costs of compliance, 

(2) The energy and nonair quality 

environmental impacts of compliance, 

(3) Any existing pollution control 

technology in use at the source, 

(4) The remaining useful life of the 

source, and 

(5) The degree of improvement in 

visibility which may reasonably be 

anticipated to result from the use of 

such technology.

These statutory factors for BART were 

codified at 40 CFR 51.308(e)(1)(ii).

In the preamble to the regional haze 

rule, we committed to issuing further 

guidelines to clarify the requirements of 

the BART provision. The purpose of this 

rulemaking is to fulfill this commitment 

by providing guidelines to assist States 

as they identify which of their BARTeligible sources should undergo a BART 

analysis (i.e., which are ‘‘sources subject 

to BART’’) and select controls in light of 

the statutory factors listed above (‘‘the 

BART determination’’). 

B. Partial Remand of the Regional Haze 

Rule in American Corn Growers v. EPA 

In response to challenges to the 

regional haze rule by various 

petitioners, the D.C. Circuit in American 

Corn Growers 2 issued a ruling striking 

down the regional haze rule in part and 

upholding it in part. This section 

discusses the court’s opinion in that 

case as background for the discussion of 

specific changes to the regional haze 

rule and the BART guidelines presented 

in the next two sections, respectively.

We explained in the preamble to the 

1999 regional haze rule that the BART 

requirements in section 169A(b)(2)(A) of 

the CAA demonstrate Congress’ intent 

to focus attention directly on the 

problem of pollution from a specific set 

of existing sources (64 FR 35737). The 

CAA requires that any of these existing 

sources ‘‘which, as determined by the 

State, emits any air pollutant which may 

reasonably be anticipated to cause or 

contribute to any impairment of 

visibility [in a Class I area],’’ shall 

install the best available retrofit 

technology for controlling emissions.3

In determining BART, the CAA requires 

the State to consider several factors that 

are set forth in section 169(g)(2) of the 

CAA, including the degree of 

improvement in visibility which may 

reasonably result from the use of such 

technology.

The regional haze rule addresses 

visibility impairment resulting from 

emissions from a multitude of sources 

located across a wide geographic area. 

Because the problem of regional haze is 

caused in large part by the long-range 

transport of emissions from multiple 

sources, and for certain technical and 

other reasons explained in that 

rulemaking, we had adopted an 

approach that required States to look at 

the contribution of all BART sources to 

the problem of regional haze in 

determining both applicability and the 

appropriate level of control. 

Specifically, we had concluded that if a 

source potentially subject to BART is 

located within an upwind area from 

which pollutants may be transported 

downwind to a Class I area, that source 

‘‘may reasonably be anticipated to cause 

or contribute’’ to visibility impairment 

in the Class I area. Similarly, we had 

also concluded that in weighing the 

factors set forth in the statute for 

determining BART, the States should 

consider the collective impact of BART 

sources on visibility. In particular, in 

considering the degree of visibility 

improvement that could reasonably be 

anticipated to result from the use of 

such technology, we stated that the 

State should consider the degree of 

improvement in visibility that would 

result from the cumulative impact of 

applying controls to all sources subject 

to BART. We had concluded that the 

States should use this analysis to 

determine the appropriate BART 

emission limitations for specific 

sources.4

In American Corn Growers v. EPA,

industry petitioners challenged EPA’s 

interpretation of both these aspects of 

the BART determination process and 

raised other challenges to the rule. The 

court in American Corn Growers

concluded that the BART provisions in 

the 1999 regional haze rule were 

inconsistent with the provisions in the 

CAA ‘‘giving the states broad authority 

over BART determinations.’’ 291 F.3d at 

8. Specifically, with respect to the test 

for determining whether a source is 

subject to BART, the court held that the 

39106 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

method that EPA had prescribed for 

determining which eligible sources are 

subject to BART illegally constrained 

the authority Congress had conferred on 

the States. Id. The court did not decide 

whether the general collective 

contribution approach to determining 

BART applicability was necessarily 

inconsistent with the CAA. Id. at 9. 

Rather, the court stated that ‘‘[i]f the 

[regional haze rule] contained some 

kind of a mechanism by which a state 

could exempt a BART-eligible source on 

the basis of an individualized 

contribution determination, then 

perhaps the plain meaning of the Act 

would not be violated. But the [regional 

haze rule] contains no such 

mechanism.’’ Id. at 12. 

The court in American Corn Growers

also found that our interpretation of the 

CAA requiring the States to consider the 

degree of improvement in visibility that 

would result from the cumulative 

impact of applying controls in 

determining BART was inconsistent 

with the language of the Act. 291 F.3d 

at 8. Based on its review of the statute, 

the court concluded that the five 

statutory factors in section 169A(g)(2) 

‘‘were meant to be considered together 

by the states.’’ Id. at 6. 

C. Changes in Response to American 

Corn Growers

Today’s rule responds to the 

American Corn Growers court’s decision 

on the BART provisions by including 

changes to the regional haze rule at 40 

CFR 51.308, and by finalizing changes 

to the BART guidelines. This section 

outlines the changes to the regional haze 

rule due to the court’s remand. It also 

explains the minor change we are 

making to the section of the regulation 

governing the use of the 1980 BART 

guidelines when conducting BART 

analyses for certain power plants for 

reasonably attributable (i.e., localized) 

visibility impairment. 

1. Determination of Which Sources Are 

Subject to BART 

Today’s action addresses the 

American Corn Growers court’s vacature 

of the requirement in the regional haze 

rule requiring States to assess visibility 

impacts on a cumulative basis in 

determining which sources are subject 

to BART. Because this requirement was 

found only in the preamble to the 1999 

regional haze rule (see 291 F.3d at 6, 

citing 64 FR 35741), no changes to the 

regulations are required. Instead, this 

issue is addressed in the BART 

guidelines, which provide States with 

appropriate techniques and methods for 

determining which BART-eligible 

sources ‘‘may reasonably be anticipated 

to cause or contribute to any 

impairment of visibility in any 

mandatory Class I Federal area.’’ These 

processes, to address the holding of 

American Corn Growers by eliminating 

the previous constraint on State 

discretion, are explained in further 

detail in sections II.D. and III below. 

2. Consideration of Anticipated 

Visibility Improvements in BART 

Determinations 

Pursuant to the remand in American 

Corn Growers, we are amending the 

regional haze rule to require the States 

to consider the degree of visibility 

improvement resulting from a source’s 

installation and operation of retrofit 

technology, along with the other 

statutory factors set out in CAA section 

169A(g)(2), when making a BART 

determination. This has been 

accomplished by listing the visibility 

improvement factor with the other 

statutory BART determination factors in 

40 CFR 51.308(e)(1)(A), so that States 

will be required to consider all five 

factors, including visibility impacts, on 

an individual source basis when making 

each individual source BART 

determination. 

D. Center for Energy and Economic 

Development v. EPA 

After the May 2004 reproposal of the 

BART guidelines, the D.C. Circuit 

decided another case where BART 

provisions were at issue, Center for 

Energy and Economic Development v. 

EPA, 398 F.3d 653, 2005 (‘‘CEED’’). In 

this case, the court granted a petition 

challenging provisions of the regional 

haze rule governing the optional 

emissions trading program for certain 

western States and Tribes (the ‘‘WRAP 

Annex Rule’’). 

The court in CEED affirmed our 

interpretation of CAA section 

169A(b)(2) as allowing for non-BART 

alternatives where those alternatives are 

demonstrated to make greater progress 

than BART. (CEED, slip. op. at 13). The 

court, however, took issue with 

provisions of the regional haze rule 

governing the methodology of that 

demonstration. Specifically, 40 CFR 

51.308(e)(2) requires that visibility 

improvements under source-specific 

BART—the benchmark for comparison 

to the alternative program—be estimated 

based on the application of BART 

controls to all sources subject to BART. 

(This section was incorporated into the 

WRAP Annex rule by reference at 40 

CFR 51.309(f)). The court held that we 

could not require this type of group 

BART approach—vacated in American 

Corn Growers in a source-specific BART 

context—even in a program in which 

State participation was wholly optional. 

The BART guidelines as proposed in 

May 2004 contained a section offering 

guidance to States choosing to address 

their BART-eligible sources under the 

alternative strategy provided for in 40 

CFR 51.308(e)(2). This guidance 

included criteria for demonstrating that 

the alternative program achieves greater 

progress towards eliminating visibility 

impairment than would BART. 

In light of the D.C. Circuit’s decision 

in CEED, we have not included the 

portion of the proposed BART 

guidelines addressing alternative 

programs in today’s rulemaking. We 

remain committed to providing States 

with the flexibility to address BART 

through alternative means, and we note 

again that our authority to do so was 

upheld in CEED. Therefore, we intend 

to revise the provisions of the regional 

haze rule governing such alternatives 

and provide any additional guidance 

needed in a subsequent rulemaking 

conducted as expeditiously as 

practicable. 

E. Relationship Between BART and the 

Clean Air Interstate Rule (CAIR) 

On March 10, 2005, EPA issued the 

Clean Air Interstate Rule (CAIR), 

requiring reductions in emissions of 

sulfur dioxide (SO2) and nitrogen oxides 

(NOX) in 28 eastern States and the 

District of Columbia. When fully 

implemented, CAIR will reduce SO2

emissions in these states by over 70 

percent and NOX emissions by over 60 

percent from 2003 levels. The CAIR 

imposes specified emissions reduction 

requirements on each affected State, and 

establishes an EPA-administered cap 

and trade program for EGUs in which 

States may participate as a means to 

meet these requirements. The 

relationship between BART and the 

Clean Air Interstate Rule (CAIR) is 

discussed in section IV. below.

F. Overview of the BART Process 

The process of establishing BART 

emission limitations can be logically 

broken down into three steps: First, 

States identify those sources which 

meet the definition of ‘‘BART-eligible 

source’’ set forth in 40 CFR 51.301. 

Second, States determine whether such 

sources ‘‘emit[] any air pollutant which 

may reasonably be anticipated to cause 

or contribute to any impairment of 

visibility [in a Class I area.]’’ A source 

which fits this description is ‘‘subject to 

BART.’’ Third, for each source subject to 

BART, States then identify the 

appropriate type and the level of control 

for reducing emissions. 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39107

5 64 FR 335740, July 1, 1999. The regional haze 

rule discusses at length why we believe that States 

should draw this conclusion. 64 FR at 35739–

35740.

6CAA section 169A(b)(2)(A).

7See 64 FR at 35714, 35721; see also Supporting 

Information for Proposed Applicability of Regional 

Haze Regulations, Memorandum by Rich Damberg 

to Docket A–95–38, U.S. Environmental Protection 

Agency, Office of Air Quality Planning and 

Standards, July 29, 1997.

Identifying BART-eligible sources.

The CAA defines BART-eligible sources 

as those sources which fall within one 

of 26 specific source categories, were 

built during the 15-year window of time 

from 1962 to 1977, and have potential 

emissions greater than 250 tons per 

year. The remand did not address the 

step of identifying BART-eligible 

sources, which is conceptually the 

simplest of the three steps. 

Sources reasonably anticipated to 

cause or contribute to visibility 

impairment (sources subject to BART).

As we noted in the preamble to the 1999 

regional haze rule, defining the 

individual contributions of specific 

sources of the problem of regional haze 

can be time-consuming and expensive. 

Moreover, Congress established a very 

low threshold in the CAA for 

determining whether a source is subject 

to BART. We are accordingly finalizing 

several approaches for States for making 

the determination of whether a source 

‘‘emits any pollutants which may 

reasonably be anticipated to cause or 

contribute to any visibility 

impairment.’’ Certain of these 

approaches would allow States to avoid 

undertaking unnecessary and costly 

studies of an individual source’s 

contribution to haze by allowing States 

to adopt more streamlined processes for 

determining whether, or which, BARTeligible sources are subject to BART. 

In 1999, we adopted an applicability 

test that looked to the collective 

contribution of emissions from an area. 

In particular, we stated that if ‘‘a State 

should find that a BART-eligible source 

is ‘reasonably anticipated to cause or 

contribute’ to regional haze if it can be 

shown that the source emits pollutants 

within a geographic area from which 

pollutants can be emitted and 

transported downwind to a Class I 

area.’’ 5 States certainly have the 

discretion to consider that all BARTeligible sources within the State are 

‘‘reasonably anticipated to cause or 

contribute’’ to some degree of visibility 

impairment in a Class I area.

This is consistent with the American 

Corn Growers court’s decision. As 

previously noted, the court’s concern 

with our original approach governing 

BART applicability determinations was 

that it would have ‘‘tie[d] the states’

hands and force[d] them to require 

BART controls at sources without any 

empirical evidence of the particular 

source’s contribution to visibility 

impairment.’’ 291 F.3d at 8. By the same 

rationale, we believe it would be an 

impermissible constraint of State 

authority for the EPA to force States to 

conduct individualized analyses in 

order to determine that a BART-eligible 

source ‘‘emits any air pollutant which 

may reasonably be anticipated to cause 

or contribute to any impairment of 

visibility in any [Class I] area.’’ 6

American Corn Growers did not decide 

whether consideration of visibility 

impact on a cumulative basis would be 

invalid in all circumstances. 291 F.3d at 

9. Given the court’s emphasis on the 

importance of the role of the States in 

making BART determinations, we 

believe that a State’s decision to use a 

cumulative analysis at the eligibility 

stage is consistent with the CAA and the 

findings of the D.C. Circuit.

We believe a State may conclude that 

all BART-eligible sources within the 

State are subject to BART.7 Any 

potential for inequity towards sources 

could be addressed at the BART 

determination stage, which contains an 

individualized consideration of a 

source’s contribution in establishing 

BART emission limits.

States also have the option of 

performing an analysis to show that the 

full group of BART-eligible sources in a 

State cumulatively may not be 

reasonably anticipated to cause or 

contribute to any visibility impairment 

in Class I areas. We anticipate that in 

most, if not all States, the BART-eligible 

sources are likely to cause or contribute 

to some visibility impairment in Class I 

areas. However, it is possible that using 

a cumulative approach, a State could 

show that its BART sources do not pose 

a problem.

Finally, States may consider the 

individualized contribution of a BARTeligible source to determine whether a 

specific source is subject to BART. 

Specifically, States may choose to 

undertake an analysis of each BARTeligible source in the State in 

considering whether each such source 

meets the test set forth in the CAA of 

‘‘emit[ting] any air pollutant which may 

reasonably be anticipated to cause or 

contribute to any impairment of 

visibility in any [Class I] area.’’

Alternatively, States may choose to 

presume that all BART-eligible sources 

within the State meet this applicability 

test, but provide sources with the ability 

to demonstrate on a case by case basis 

that this is not the case. Either approach 

appears consistent with the D.C. 

Circuit’s statement that a collective 

contribution approach may be 

appropriate so long as the States are 

allowed to exempt sources on the basis 

of an individualized contribution 

determination. 291 F.3d at 8. 

Today’s guidelines include different 

options States can use to assess whether 

source should be subject to BART. 

States need to determine whether to 

make BART determinations for all of 

their BART-eligible sources, or 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. For assessing the impact of BARTeligible sources on nearby Class I areas, 

we are including a process whereby the 

States would use an air quality model 

able to estimate a single source’s 

contribution to visibility impairment 

and a different process whereby States 

could exempt groups of sources with 

common characteristics based on 

representative model plant analyses. 

Finally, States may use cumulative 

modeling to show that no sources in a 

State are subject to BART. 

The BART determination. The State 

must determine the appropriate level of 

BART control for each source subject to 

BART. Section 169A(g)(7) of the CAA 

requires States to consider the following 

factors in making BART determinations: 

(1) The costs of compliance, (2) the 

energy and nonair quality 

environmental impacts of compliance, 

(3) any existing pollution control 

technology in use at the source, (4) the 

remaining useful life of the source, and 

(5) the degree of improvement in 

visibility which may reasonably be 

anticipated to result from the use of 

such technology. The remand did not 

address the first four steps of the BART 

determination. The remand did address 

the final step, mandating that we must 

permit States to take into account the 

degree of improvement in visibility that 

would result from imposition of BART 

on each individual source when 

deciding on particular controls. 

The first four factors are somewhat 

similar to the engineering analysis in 

the original BART guidelines proposed 

in 2001 and reproposed in 2004. The 

BART guidelines also contains a 

detailed discussion of available and 

cost-effective controls for reducing SO2

and NOX emissions from large coal-fired 

electric generating units (EGUs). 

For assessing the fifth factor, the 

degree of improvement in visibility from 

various BART control options, the 

States may run CALPUFF or another 

appropriate dispersion model to predict 

visibility impacts. Scenarios would be 

39108 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

run for the pre-controlled and postcontrolled emission rates for each of the 

BART control options under review. 

The maximum 24-hour emission rates 

would be modeled for a period of three 

or five years of meteorological data. 

States have the flexibility to develop 

their own methods to evaluate model 

results. 

III. Detailed Discussion of the Final 

BART Guidelines 

A. Introduction 

In this section of the preamble, we 

discuss changes or clarifications to the 

reproposed BART guidelines. Where 

relevant, we also respond to comments 

received during the comment period on 

the 2001 proposal. For each provision of 

the guidelines that we are changing or 

clarifying, we provide discussion of, as 

appropriate:

—Background information, 

—How the provision was addressed in 

the May 2004 reproposal (and in the 

2001 proposal, if different from the 

reproposal), 

—A summary of comments received on 

the provision, either from the May 

2004 reproposal, from the July 2001 

proposal, or from both, and 

—The changes or clarifications that we 

are finalizing and the reasons for 

these changes or clarifications. 

B. Scope of the Rule—Whether To 

Require States To Follow the Guidelines 

for All BART Sources 

Background. Section 169A(b)(1) of the 

CAA requires EPA to issue regulations 

to provide guidelines to States on the 

implementation of the visibility 

program. In addition, the last sentence 

of section 169A(b) states:

In the case of a fossil-fuel fired generating 

powerplant having a capacity in excess of 

750 megawatts, the emission limitations 

required under this paragraph shall be 

determined pursuant to guidelines, 

promulgated by the Administrator under 

paragraph (1).

This statutory requirement clearly 

requires us to promulgate BART 

guidelines that the States must follow in 

establishing BART emission limitations 

for power plants with a total capacity 

exceeding the 750 megawatt cutoff. The 

statute is less clear regarding the import 

of the guidelines for sources other than 

750 megawatt power plants.

Proposed rules. Both the 2001 

proposal and the 2004 reproposal 

included a requirement for States to 

follow the procedures set out in the 

guidelines in determining BART for 

sources in all of the 26 listed BART 

categories. The 2001 proposal requested 

comment on whether the regional haze 

rule should: (1) Require the use of the 

guidelines only for 750 megawatt 

utilities, with the guidelines applying as 

guidance for the remaining categories, 

or (2) require the use of the guidelines 

for all of the affected source categories. 

Comments. We received comments on 

this issue in both 2001 and 2004. 

Comments varied widely on whether we 

can or should require the use of the 

guidelines for all of the affected source 

categories. 

Comments from State, local and tribal 

air quality agencies generally supported 

our proposal to require the use of the 

guidelines for all of the source 

categories. These comments cited a need 

for national consistency in the 

application of the BART requirement 

across the source categories, and from 

State to State. One State agency 

commenter questioned our legal 

authority to require the use of the 

guidelines for all source categories; and 

several State agency commenters, while 

supporting the proposal, requested that 

we provide clarification of the legal 

authority for requiring the States to use 

the guidelines in establishing BART 

emission limitations for all categories. 

Comments from the utility industry, 

from various manufacturing trade 

groups, and from individual companies 

were critical of the proposal to require 

States to follow the guidelines generally. 

Many commenters also argued that EPA 

lacked the authority to issue guidelines 

for any industrial category other than 

750 megawatt powerplants, whether the 

use of such guidelines were mandatory 

or not. Other commenters stated that the 

language in the CAA clearly restricts the 

scope of mandatory guidelines to larger 

powerplants. The commenters cited the 

legislative history of the 1977 Clean Air 

Act amendments in support of this 

position, and frequently claimed that 

requiring the guidelines for all 26 

categories of sources would deprive 

States of flexibility in implementing the 

program. 

Comments from environmental 

organizations and the general public 

supported the approach in the proposed 

rule and stated that EPA is obligated to 

establish regional haze BART guidelines 

by rulemaking for all 26 categories of 

stationary sources. Environmental 

organization comments noted that while 

Congress expressed a particular concern 

for 750 MW powerplants, this added 

emphasis on one sector does not change 

requirements in the Act for all BARTeligible sources. Accordingly, these 

commenters believed that we should not 

construe a special emphasis on 

powerplants as a restriction on our 

authority to require use of the 

guidelines for all categories. 

Final rule. The CAA and the relevant 

legislative history make clear that EPA 

has the authority and obligation to 

publish mandatory guidelines for 

powerplants exceeding 750 megawatts. 

As previously noted, Congress in 

section 169A(b) of the CAA expressly 

provided that emission limitations for 

powerplants larger than 750 megawatts 

‘‘shall be determined pursuant to 

guidelines promulgated by the 

Administrator.’’ (Emphasis added). This 

unambiguous language leaves little 

room to dispute that the guidelines EPA 

is required to promulgate must be used 

by States when making BART 

determinations for this class of sources. 

Having carefully considered the 

comments and further reviewed the 

CAA and the legislative history, we 

have concluded that it would not be 

appropriate for EPA to require States to 

use the guidelines in making BART 

determinations for other categories of 

sources. The better reading of the Act 

indicates that Congress intended the 

guidelines to be mandatory only with 

respect to 750 megawatt powerplants. 

Thus, while we acknowledge the State 

agency comments and the policy 

reasons support consistency across 

States, we are not requiring States to use 

the BART guideline for these other 

categories. In response to State concerns 

about equitable application of the BART 

requirement to source owners with 

similar sources in different States, we 

do encourage States to follow the 

guidelines for all source categories but 

are not requiring States to do so. States 

should view the guidelines as helpful 

guidance for these other categories. 

We disagree with comments that the 

CAA and the legislative history prohibit 

us from issuing guidance for other 

source categories. As the guidelines 

make clear, States are not required to 

follow the approach in the guidelines 

for sources other than 750 megawatt 

powerplants. As such, although we 

believe that the guidelines provide 

useful advice in implementing the 

BART provisions of the regional haze 

rule, we do not believe that they hamper 

State discretion in making BART 

determinations. 

C. How To Identify BART-Eligible 

Sources

Section II of the BART guidelines 

contains a step-by-step process for 

identifying stiationary sources that are 

‘‘BART-eligible’’ under the definitions 

in the regional haze rule. The four basic 

steps are: 

Step 1: Identify the emission units in 

the BART categories. 

Step 2: Identify the start-up dates of 

those emission units. 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39109

Step 3: Compare the potential 

emissions from units identified in Steps 

1 and 2 to the 250 ton/year cutoff. 

Step 4: Identify the emission units 

and pollutants that constitute the BARTeligible source. 

In this section of the preamble, we 

discuss some of the comments we 

received on the steps in this process, 

and any changes we are making in light 

of those comments. 

Step 1: Identify the Emission Units in 

the BART Categories 

The BART guidelines list the 26 

source categories that the CAA uses to 

describe the types of stationary sources 

that are BART-eligible. Both proposals 

clarified the descriptions of particular 

source categories. 

Comments. The final rule addresses 

comments on the following source 

categories. Some comments discussed 

below were submitted in response to the 

2001 propoosal and were not addressed 

in the reproposal; other comments were 

submitted in response to the reproposal 

in 2004. 

(1) ‘‘Charcoal production facilities.’’

We received comments in 2001 from 

two industry trade groups requesting 

that the final guidelines explicitly 

exclude ‘‘low-emission’’ charcoal 

production facilities from BART. These 

comments cited a 1975 study 

considered by Congress in development 

of the BART category list in the 1977 

CAA amendments. This 1975 study 

noted that some charcoal production 

facilities have much higher emissions 

factors (i.e., 352 pounds of PM per ton 

of charcoal produced versus 20 to 25 

pounds of PM per ton of charcoal 

produced). Accordingly, the comments 

asserted that the intent of Congress in 

the 1977 CAA amendments was to 

provide incentives for higher-emitting 

facilities to reduce their emissions, 

rather than to make the entire category 

BART-eligible. 

(2) ‘‘Chemical process plants.’’ In 

2001 a trade group representing the 

pharmaceutical industry requested that 

we determine in the guidelines that the 

term ‘‘chemical process plants’’ does not 

include pharmaceutical plants. 

(3) ‘‘Primary aluminum ore 

reduction.’’ Comments from the 

aluminum industry in 2001 noted that 

not all emissions units at these facilities 

are necessarily involved in ‘‘primary ore 

reduction.’’ Thus, the comments 

recommended that we clarify that 

contiguous sources that are not related 

to primary aluminum ore reduction, 

such as fabricating facilities and ingot 

operations, are not BART-eligible. 

Further, the comments recommended 

that we use definitions in the NSPS for 

primary aluminum plants to describe 

the BART-eligible emissions units. 

(4) ‘‘Fossil-fuel fired steam electric 

plants of more than 250 million Btu/

hour heat input.’’ The 2004 reproposal 

contained the clarification, requested by 

commenters, that this source category 

refers only to those fossil-fuel fired 

steam electric plants that generate 

electricity for sale. One commenter 

objected to this clarification on the basis 

that emissions from co-generators would 

be excluded; many other commenters 

supported the clarification. Another 

commenter requested that we also 

clarify that this category includes only 

those steam electric plants that burn 

greater than 50 percent fossil fuel, in 

order to be consistent with the 

definition of fossil-fuel boilers proposed 

in the guidelines. Other commenters 

requested that we clarify whether the 

definition includes units which are 

located at a steam electric plant, but 

which themselves are not in any of the 

26 BART source categories, such as 

simple cycle turbines, emergency diesel 

engines, and reciprocating internal 

combustion engines (RICE). 

Several commenters opined that the 

category should exclude combined cycle 

units with heat recovery steam 

generators that lack auxiliary firing, 

arguing that these units should count as 

simple cycle turbines. These 

commenters pointed to other EPA 

regulatory programs that treat combined 

cycle units with supplemental firing 

differently from combined cycle units 

without supplemental firing. They 

argued that we should only consider a 

combined cycle unit to be a ‘‘steam 

electric plant’’ if it has supplemental 

firing. 

(5) ‘‘Fossil-fuel boilers of more than 

250 million Btu/hour heat input.’’ The 

2004 reproposal clarified that this 

category should be read as including 

only those boilers individually greater 

than 250 million Btu/hour heat input. 

We received many comments on this 

interpretation, both in favor and 

opposed. Those favoring this 

interpretation (generally industry 

commenters) cited the implementation 

burden that including smaller boilers 

would pose, the high cost-effectiveness 

of controlling smaller boilers, and the 

relatively smaller impact on regional 

haze that smaller boilers would pose. 

They also noted that this interpretation 

is most consistent with definitions in 

the NOX SIP call and new source 

performance standards (NSPS).

Commenters opposing this 

interpretation (environmental groups, 

one state, and one regional planning 

organization) noted that regarding all 

boilers, irrespective of size, as BARTeligible so long as the aggregate heat 

input exceeds 250 million Btu/hour is 

more consistent with the definition of 

stationary source under the Prevention 

of Significant Deterioration (PSD) 

program. These commenters noted that 

under the CAA, BART and PSD are 

complementary programs aimed at 

regulating the same source categories; 

either one or the other applies 

depending upon when the source was 

constructed. 

The 2004 reproposal also clarified 

that if a boiler smaller than 250 million 

Btu/hour heat input is an integral part 

of an industrial process in a BART 

source category other than electric 

utilities, then the boiler should be 

considered part of the BART-eligible 

source in that category. Under these 

circumstances, the boiler, as part of the 

BART-eligible source, should be 

considered for emission control. Some 

commenters opposed this interpretation, 

asserting that it would result in an 

‘‘arbitrary and capricious’’

inconsistency, in that some smaller 

boilers would be BART-eligible, and 

others would not. These commenters 

also noted that these boilers could be 

included in regional haze SIPs as 

necessary for making ‘‘reasonable 

progress’’ toward CAA visibility goals, 

even if they are not considered to be 

BART-eligible. 

Final rule. After considering the 

comments, we have made the following 

determinations on the definitions of the 

following source categories: 

(1) ‘‘Charcoal production facilities.’’

We believe that in using the term 

‘‘charcoal production facilities’’

Congress intended to encompass all 

types of charcoal production facilities. 

We do not agree with comments that 

any inferences can necessarily be made 

regarding the presence of different PM 

emission factors for different types of 

charcoal production facilities in the 

1975 report. For example, if Congress 

only intended to regulate a subset of the 

charcoal production industry, then we 

believe Congress could have easily 

indicated this in the source category 

title, as was done for ‘‘kraft pulp mills’’

and for ‘‘coal cleaning plants (thermal 

dryers).’’ We also note that it is more 

likely that plants in the charcoal 

production industry with lower 

emission factors have emissions that are 

less than the 250 tons per year cutoff for 

BART eligibility. 

(2) ‘‘Chemical process plants.’’ We 

believe that there is a clear precedent to 

include pharmaceutical manufacturing 

operations as ‘‘chemical process 

plants.’’ In the standard industrial 

classification (SIC) system, 

pharmaceutical operations are generally 

39110 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

8See http://www.epa.gov/Region7/programs/

artrd/air/nsr/nsrmemos/turbines.pdf.

in SIC codes 2833 and 2834, which are 

a subset of 2-digit category 28 

‘‘Chemical and Allied products.’’

Similarly, in the new North American 

Industrial Classification Codes (NAICS), 

pharmaceutical manufacturing is codes 

32541 and 32542, which is a subset of 

the ‘‘chemical manufacturing subsector’’

which is code 325. Accordingly, in the 

PSD program, pharmaceutical plants 

have been treated as ‘‘chemical process 

plants.’’ The commenter is correct in 

noting that EPA has consistently 

distinguished between chemical 

manufacturing and pharmaceutical 

manufacturing. Examples where 

different standards or guidelines are 

established included control technique 

guideline (CTG) documents, NSPS 

standards under section 111 of the CAA, 

and, most recently, maximum 

achievable control technology (MACT) 

standards under section 112 of the CAA. 

We do not agree that these 

differentiations for emissions standards 

necessarily require differentiation for 

purposes of determining BART 

eligibility. Therefore we believe 

pharmaceuticals should not be excluded 

from BART. However, we expect that 

because of the MACT standards, there is 

a very low probability that BART 

determinations will lead to further 

control requirements from chemical 

production processes at pharmaceutical 

plants.

(3) ‘‘Primary aluminum ore 

reduction.’’ We agree with commenters 

that BART-eligible units in this source 

category should be defined consistently 

with the NSPS definition for primary 

aluminum ore reduction. Therefore we 

have added a clarification to that effect 

in the final BART guidelines. We note 

that this definition is also consistent 

with the definition at 40 CFR 63.840, 

which establishes applicability for this 

source category for the MACT program. 

(4) ‘‘Fossil-fuel fired steam electric 

plants of more than 250 million Btu/

hour heat input.’’ We have retained the 

clarification that this source category 

refers only to those fossil-fuel fired 

steam electric plants that generate 

electricity for sale. We believe that this 

clarification helps to distinguish those 

plants that are electric utilities from 

plants in other industrial categories. We 

also believe that while large cogenerators would be excluded from the 

fossil-fuel fired steam electric plant 

source category, most large cogenerators will be BART-eligible under 

the fossil-fuel fired boilers source 

category. 

We do not believe it makes sense for 

this category to include only those 

steam electric plants that burn greater 

than 50 percent fossil fuel. We do not 

believe that a boiler should be excluded 

from BART review simply because it is 

located at a plant which burns less than 

50 percent fossil fuel. Emissions from 

any such boiler could be a significant 

contributor to regional haze, and as 

such, we believe that each fossil-fuel 

fired boiler merits a BART review. 

We do wish to clarify that units which 

are located at a steam electric plant, but 

which themselves are not in any of the 

26 BART source categories, should not 

be considered to be BART-eligible units. 

We believe that Congress intended that 

BART review be focused on units in the 

source categories it delineated. This 

interepretation is most consistent with 

the definition of BART-eligible source 

as we have explained it elsewhere in 

this preamble in reference to whether 

entire plants are included if only some 

units at the plant meet the statutory 

criteria. 

Finally, we believe that all combined 

cycle units are included in the 

definition of fossil fuel fired steam 

electric plant, regardless of whether the 

combined cycle unit’s heat recovery 

steam generator lacks auxilliary firing. 

Commenters are correct that some EPA 

programs have treated combined cycle 

units with supplemental firing 

differently from combined cycle units 

without supplemental firing. However, 

while some EPA programs do not 

consider a unit to be a combined cycle 

unit unless it contains supplemental 

firing, the definition at issue here is the 

definition of fossil-fuel fired steam 

electric plant, not fossil-fuel fired unit. 

The CAA defines both ‘‘stationary 

source’’ (for visibility purposes) and 

‘‘major emitting facility’’ (for PSD 

purposes) to include ‘‘fossil fuel fired 

steam electric plants.’’ In previous 

guidance for PSD, we have explained 

that combined cycle gas turbines do fall 

within the category of ‘‘fossil-fuel fired 

steam electric plants.’’ 8

(5) ‘‘Fossil-fuel boilers of more than 

250 million Btu/hour heat input.’’ We 

have decided to retain the interpretation 

that this category should be read as 

including only those boilers 

individually greater than 250 million 

Btu/hour heat input. We agree with 

commenters who noted that including 

smaller boilers would pose considerable 

implementation burden. As noted in the 

2004 reproposal notice, we do not 

believe that this interpretation is likely 

to have a substantial impact. Because 

smaller boilers are generally less costeffective to control, we believe that 

BART review would be unlikely to 

result in a significant amount of control 

on these boilers.

We are also retaining the clarification 

that if a boiler smaller than 250 million 

Btu/hour heat input is an integral part 

of an industrial process in a BART 

source category other than electric 

utilities, then the boiler should be 

considered part of the BART-eligible 

source in that category. (By ‘‘integral to 

the process’’, we mean that the process 

uses any by-product of the boiler, or 

vice-versa. We have added this 

clarification to the definition in the 

BART guidelines.) We believe that if a 

State is already considering a BARTeligible industrial process for control, 

and a boiler is integrated into that 

process, it makes common sense not to 

prematurely rule out control options 

any of the emissions from that process 

as a whole. (Note that a boiler which is 

not integral, but is simply attached to a 

plant, should not be included.) For 

example, Kraft pulp mills may have 

boilers that are not serving the energy 

infrastructure of the plant but typically 

are serving a process directly by using 

the waste liquor from the process. 

Including such a boiler in consideration 

of control options for the process adds 

minimal additional burden while 

leaving maximum discretion to the State 

in determining BART for the process as 

a whole. 

We are also clarifying today that we 

have determined that this category 

should include all individual boilers of 

greater than 250 million Btu/hour heat 

input burning any amount of fossil fuel, 

as opposed to only those boilers that 

burn greater than 50 percent fossil fuel. 

We believe that it is quite possible that 

boilers of this size could contribute to 

regional haze in a Class I area even if 

they burn less than 50 percent fossil 

fuel. Therefore we believe that each 

fossil fuel-fired boiler merits a BART 

review. 

Step 2: Identify the Start-up Dates of 

Those Emission Units 

Background. BART applies only to a 

major stationary source which ‘‘was in 

existence on August 7, 1977 but which 

has not been in operation for more than 

fifteen years as of such date.’’ The 

visibility regulations define ‘‘in 

existence’’ and ‘‘in operation’’ in 40 CFR 

51.301. Under these regulations, 

promulgated in 1980, ‘‘in existence’’

means

that the owner or operator has obtained all 

necessary preconstruction approvals or 

permits * * * 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.

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39111

9However, sources reconstructed after 1977, 

which reconstruction had gone through NSR/PSD 

permitting, are not BART-eligible. 10See CAA section 193.

The term ‘‘in operation’’ means engaged 

in activity related to the primary design 

function of the source. 

Step 2 also addresses the treatment of 

‘‘reconstructions’’ and ‘‘modifications.’’

Under the definition of BART-eligible 

facility, sources which were in 

operation before 1962 but reconstructed 

during the 1962 to 1977 time period are 

treated as new sources as of the time of 

reconstruction.9 The same policies and 

procedures for identifying reconstructed 

‘‘affected facilities’’ under the NSPS are 

used to determine whether a source has 

been reconstructed for purposes of the 

BART requirements. ‘‘Modifications’’

under the CAA refers to physical change 

or change in the method of operation at 

a source which has led to an increase in 

emissions. In the proposed BART 

guidelines, we stated that the best 

interpretation of the visibility 

provisions is that a modification to a 

source does not change an emission’s 

unit construction date for purposes of 

BART applicability. We requested 

comment on an alternative 

interpretation that we believed would 

be more difficult to implement. Under 

this approach, sources built before 1962 

but modified during the 1962 to 1977 

time frame would be considered ‘‘new’’

at the time of modification.

Comments. We received comments in 

2001 and 2004 on the discussion in the 

guideline of the term ‘‘in existence.’’

These comments were critical of our 

statement in the guidelines that sources 

which had ‘‘commenced construction,’’

that is, those which had entered into 

binding contracts, would be considered 

to be in existence, even if actual 

operations did not begin until after the 

August 7, 1977 cutoff date. These 

commenters asserted that Congress did 

not intend to treat a source as ‘‘existing’’

in 1977 if it was not yet built. 

Other commenters interpreted the 

proposed guidelines as expanding the 

definition of BART-eligible sources by 

requiring States to find that all emission 

units at a facility are BART-eligible if 

one part of the facility was built within 

the 1962–1977 time period. Other 

comments did not suggest that we had 

already expanded the definition in the 

proposed guidelines, but did suggest 

that we should expand the definition in 

that way in the final guidelines. Some 

commenters noted that there was a 

degree of confusion in the regulated 

community on whether the proposed 

guidelines were requiring BART for all 

units at a power plant, including those 

that were in operation before August 7, 

1962, if these units are co-located with 

one or more units that were put in place 

within the 1962–1977 time period. 

These commenters requested that we 

clarify that such pre-1962 units would 

not be BART-eligible.

Some commenters asserted that our 

proposed approach is unworkable, 

because the approach requires States to 

identify all emissions units put in place 

between the 1962 and 1977. Some of 

these commenters asserted that 

Congress intended that BART would 

apply only if entire plants satisfy the 

statutory criteria. These comments 

suggested that BART should apply only 

if an entire plant that is one of the 26 

listed source category types had been 

placed in operation at a discrete point 

within the 15 year time period for BART 

eligibility. These commenters asserted 

that our proposed guidelines, which 

involved the identification and 

aggregation of individual emission units 

within the 1962–1977 time period, were 

inconsistent with Congress’ intent. 

Other comments suggested that EPA 

could improve implementation of the 

program by covering discrete projects 

rather than individual emissions units. 

A few commenters suggested that for 

purposes of identifying such discrete 

projects, we consider using the term 

‘‘process or production unit’’ that we 

used in hazardous air pollutant 

regulations under CAA section 112(g). 

One commenter requested that the 

guidelines clarify that emissions from 

‘‘linked’’ emission units should not be 

considered in determining BART 

eligibility. That is, even if changes in 

emissions from one unit could affect the 

emissions from a ‘‘linked’’ unit that was 

not put in place within the 1962–1977 

time period, that would not affect 

whether the ‘‘linked’’ unit was BARTeligible. Another commenter suggested 

that the approach set forth in the 

guidelines for identifying BART-eligible 

sources is inappropriate because the 

particular set of units identified as 

BART-eligible will not necessarily 

‘‘provide a reasonable and logical 

platform for the installation of 

controls.’’

Other commenters stated that 

facilities that had been modified after 

1977 should not be included in the pool 

of sources subject to BART. Such 

facilities, it was argued, already meet 

the BART requirements because of the 

controls installed to meet the 

requirements of PSD, NSR, or the NSPS. 

Final rule. We disagree with the 

comments recommending that we 

interpret the term ‘‘in existence’’ to refer 

to sources that are in actual operation. 

The discussion of this term in Step 2 is 

based on the regulatory definition 

which has been in place since 1980. The 

guidelines reiterate this definition and 

provide examples of its application. 

Interpreting the term ‘‘in existence’’ as 

suggested by commenters would not be 

consistent with the plain language of the 

regulations. 

In the 2001 and 2004 proposed 

guidelines, we noted that ‘‘the term ‘in 

existence’ means the same thing as the 

term ‘commence construction’ as that 

term is used in the PSD regulations.’’

Commenters were critical of this 

statement, claiming that EPA was 

unlawfully reinterpreting section 169A 

in the guidelines. The statement in Step 

2 of guidelines, however, is not a 

reinterpretation of the term ‘‘in 

existence,’’ but merely a statement 

noting that the definitions used in the 

visibility regulations and the PSD 

regulations are essentially identical. 

To the extent that commenters are 

claiming that the existing regulatory 

definition of ‘‘in existence’’ is unlawful, 

EPA’s interpretation of this term in 

promulgating the 1980 regulations was 

a reasonable one. First, it is worth 

noting that the regulations adopting this 

interpretation of the term ‘‘in existence’’

were in effect in 1990 and implicitly 

endorsed by Congress in its 1990 

amendments to the CAA.10 Moreover, 

the definition at issue accurately reflects 

Congress’ intent that the BART 

provision apply to sources which had 

been ‘‘grandfathered’’ from the new 

source review permit requirements in 

parts C and D of title I of the CAA. For 

all the above reasons, we are neither 

revising the regional haze regulations to 

change the definition of ‘‘in existence,’’

nor adopting a strained interpretation of 

the regulation in the guidelines.

We agree with commenters that the 

definition of ‘‘BART-eligible source’’

does not require States to find that all 

emission units at a facility are subject to 

the requirement of the BART provisions 

if only one part of the facility was built 

within the 1962–1977 time period. We 

received comments on this issue in 2001 

and clarified in 2004 that the BART 

guidelines do not direct States to find 

that all boilers at a facility are BARTeligible if one or more boilers at the 

facility were put in place during the 

relevant time period. Under Step 2 of 

the process for identifying BARTeligible sources set out in the 

guidelines, States are required to 

identify only those boilers that were put 

in place between 1962 and 1977. As 

explained in the preamble to the 2004 

reproposed guidelines, only these 

boilers are potentially subject to BART. 

39112 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

We do not agree with those 

commenters claiming that Congress 

clearly intended to apply BART only if 

an ‘‘entire plant’’ was put into place 

between 1962 and 1977. Most of the 

BART source categories are broad 

descriptions types of industrial facilities 

such as ‘‘kraft pulp mills,’’ ‘‘petroleum 

refineries’’ or ‘‘primary copper 

smelters.’’ For such source categories, 

the implication of commenters’

argument would that if any portion of 

the plant was in operation before 

August 7, 1962, then Congress intended 

to exempt the entire plant from BART. 

Such an interpretation is problematic 

and inequitable. For example, under 

this approach BART would not apply if 

a company chose to expand its 

production by building a second 

production line at an existing line in 

1965, but would apply if the same 

company chose to build the same 

equipment at a greenfield site. Under 

the approach set forth in the guidelines, 

such a production line would be treated 

similarly under either set of facts. We do 

not believe that either the plain 

language of the statute or the relevant 

legislative history indicate that Congress 

intended for major-emitting sources of 

visibility-impairing pollutants to be 

exempted from the BART requirements 

because a plant contains some emission 

units that began operation before 1962. 

Also, we disagree with the comment 

that modifications after 1977 should 

change an emissions’ unit date of 

construction for purposes of BART 

applicability. The commenter’s 

suggestion that such sources already 

meet BART requirements may be 

accurate, but does not provide a basis 

for exempting the source from review. 

As we note in the guideline, the review 

process will take into account the 

controls already in place and the State 

may find that these controls are 

consistent with BART. 

We agree with the comments related 

to ‘‘linked’’ emission units. The 

comment appears to address whether 

emissions from the ‘‘linked’’ units are 

considered in determining BART 

eligibility. In the guidelines, we are 

focusing on only the emissions units 

that were put in place during the 1962 

to 1977 dates and the emissions from 

those units. We agree that even if 

changes in emissions from one unit 

could affect the emissions from a 

‘‘linked’’ unit that was not put in place 

within the 1962–1977 time period, this 

would not affect whether the ‘‘linked’’

unit was BART-eligible. 

We disagree with commenters that the 

approach set forth in the guidelines for 

identifying BART-eligible sources is 

inappropriate because the particular set 

of units identified as BART-eligible will 

not necessarily ‘‘provide a reasonable 

and logical platform for the installation 

of controls.’’ We do not agree that this 

factor is relevant to the identification of 

those emissions units which meet the 

definition of BART-eligible source. Such 

factors are important in the States’

consideration of control strategies and 

options but do not clearly relate to the 

first step of identifying those sources 

which fall within one of 26 source 

categories, were built during the 15 year 

window of time from 1962 to 1977, and 

have potential emissions of greater than 

250 tons per year. We do thus agree 

generally with the commenter’s 

recommendation of allowing States to 

consider the particular history and 

control potential of units in determining 

BART, but do not agree that it is 

relevant to the predicate question of 

identifying the BART-eligible source. 

Finally, the approach to identifying a 

‘‘BART-eligible source’’ in the 

guidelines is based on the definitions in 

the regional haze rule of the relevant 

terms. For 750 MW power plants, States 

are required to apply the definitions as 

set forth in the guidelines; for other 

sources, States may adopt a different 

approach to the task of identifying 

BART-eligible sources, so long as that 

approach is consistent with the Act and 

the implementing regulations. In other 

words, while the guidelines adopt an 

approach for large power plants which 

involves the aggregation of all emissions 

units put into place between 1962 and 

1977, States have the flexibility to 

consider other reasonable approaches to 

the question of identifying BARTeligible sources for other source 

categories. 

For 750 MW power plants, many of 

the issues identified by commenters 

with the approach of looking at a facility 

on an emission unit by emission unit 

basis do not exist. Unlike many types of 

industrial processes, power plants 

consist generally of a discrete number of 

very large emission units. For other 

types of facilities such as kraft pulp 

mills or chemical process plants which 

may have many small emission units 

that have undergone numerous changes, 

the guidelines do not limit the ability of 

the States to approach the question of 

identifying BART-eligible sources in 

ways which make sense for the 

particular sources given their design 

and history. 

Step 3: Compare the Potential Emissions 

to the 250 Ton/Yr Cutoff. 

Background. Step 3 of the guidelines 

addresses the question of whether the 

units identified in Steps 1 and 2 have 

emissions in excess of the threshold for 

major sources set forth in section 

169A(g)(7) of the CAA. The guidelines 

pose the following questions to help the 

States in determining whether the 

relevant emissions units have the 

potential to emit in excess of the 250 

tons per year threshold of any single 

visibility-impairing pollutant: 

(1) What pollutants should I address? 

The 2001 proposed guidelines 

included the following list of visibilityimpairing pollutants: SO2, NOX, 

particulate matter, volatile organic 

compounds (VOCs), and ammonia. We 

proposed in 2001 and again in 2004 that 

States use PM10 as the indicator for 

particulate matter. As explained in the 

guidelines, there is no need to have 

separate 250 ton thresholds for PM10

and PM2.5 because emissions of PM10

include the components of PM2.5 as a 

subset. In addition, because of various 

uncertainties associated with regulating 

VOCs and ammonia, we requested 

comment in 2004 on the level of 

discretion States should exercise in 

making BART determinations for VOCs 

and took ammonia off the list of 

visibility-impairing pollutants.

In both proposals, we clarified that 

the 250 tons per year cutoff applies to 

emissions on a pollutant by pollutant 

basis. In other words, a source is subject 

to BART only if it emits at least 250 tons 

per year of an individual visibilityimpairing pollutant. 

(2) What does the term ‘‘potential’’

emissions mean? 

The proposed guidelines in 2001 and 

the reproposed guidelines in 2004 

excerpt the definition of ‘‘potential to 

emit’’ from the regulations at 40 CFR 

51.301. As the definition makes clear, 

the potential to emit of a source is 

calculated based on its capacity to emit 

a pollutant taking into account its 

physical and operational design. Under 

this definition, federally enforceable 

emission limits may be taken into 

account in calculating a source’s 

potential emissions; however, emission 

limitations which are enforceable only 

by State and local agencies, but not by 

EPA and citizens in Federal court, 

cannot be used to limit a source’s 

potential to emit for purposes of the 

regional haze program. 

(3) What is a ‘‘stationary source?’

As explained above, States are 

required to make a BART determination 

only for ‘‘stationary sources’’ of a certain 

size that fall within one of 26 types of 

industrial categories listed in the statute 

and that were built within a certain time 

frame. The regional haze rule contains 

definitions that are relevant to the 

determination of the emissions units 

that comprise a ‘‘stationary source.’’

First, the regulations at 40 CFR 51.301 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39113

11See http://wrapair.org/forums/ioc/meetings/

030728/index.html (specifically presentation by 

John Vimont, National Park Service).

12NARSTO, Particulate Matter Assessment for 

Policy Makers: A NARSTO Assessment. P. 

McMurry, M. Shepherd, and J. Vickery, eds. 

Cambridge University Press, Cambridge, England 

(2004).

13See Fine particles: Overview of Atmospheric 

Chemistry, Sources of Emissions, and Ambient 

Monitoring Data, Memorandum to Docket OAR 

2002–0076, April 1, 2005. 14These methods are described at the following 

Web site: http://vista.cira.colostate.edu/improve/

Tools/ReconBext/reconBext.htm.

15 Grand Canyon Visibility Transport 

Commission, Recommendations for Improving 

Western Vistas, Report to the U.S. EPA, June 10, 

1996.

define ‘‘stationary source’’ as ‘‘any 

building, structure, facility, or 

installation which emits or may emit 

any air pollutant.’’ Second, the terms 

‘‘building, structure, or facility’’ are 

defined in part based on grouping 

pollutant-emitting activities by 

industrial category:

Building, structure, or facility means 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).

In the 2001 proposed guideline, we 

noted that support facilities, i.e.

facilities used to convey, store, or 

otherwise assist in the production of the 

principal product, are considered to fall 

within the same industrial grouping as 

the primary facility. To clarify this, in 

2004 we proposed to add language to 

the guideline noting that emission units 

at a plant, even if they are a ‘‘support 

facility’’ for purposes of other programs, 

would not be subject to BART unless 

they were within one of the 26 listed 

source categories and were built within 

the 1962 to 1977 time frame. 

Discussion of ‘‘What Pollutants Should 

I Address?’’

Comments. PM10 as an indicator. 

Some comments questioned the use of 

PM10 (which includes both coarse and 

fine particulate matter) as the indicator 

for particulate matter. Commenters 

noted that the coarse fraction, that is 

particulate matter between 10 and 2.5 

micrograms in diameter, fundamentally 

differs compared to the fine mass in 

how it interacts with light. Commenters 

suggested that only the fine mass (PM2.5) 

component of particulate matter is 

likely to contribute to visibility 

impairment. Accordingly, these 

commenters recommended that the 250 

ton cutoff for particulate matter should 

be based upon emissions of PM2.5.

Ammonia. Many commenters 

addressed the exclusion of ammonia 

from the list of visibility-impairing 

pollutants. A number of commenters, 

primarily from industry but also from 

one state and one regional planning 

organization, supported the exclusion of 

ammonia. These commenters generally 

cited the complexity and variability of 

ammonia’s role in the formation of 

PM2.5 in the atmosphere, the relative 

greater benefits of controlling NOX and 

SO2, the uncertainties in the inventory 

of ammonia emissions, and the inherent 

complexities of gauging the contribution 

of potential ammonia reductions to 

improving visibility in Class I areas. In 

addition, commenters noted that few, if 

any, point sources emit ammonia in 

amounts that exceed the 250 ton per 

year threshold. 

Other commenters, including a 

number of environmental groups and 

several states, regional planning 

organizations, and industry 

commenters, argued that ammonia 

should be included in the list of 

visibility-impairing pollutants in the 

guidelines. In support of this view, 

commenters cited evidence that 

ammonia is a known precursor to PM2.5. 

One commenter noted that 

improvements are being made to 

ammonia inventories and to the 

understanding of ammonia’s role in the 

formation of haze. Other commenters 

pointed to a National Park Service (NPS) 

analysis of monitoring data that 

indicates that visibility-impairment due 

to nitrate aerosol formation (to which 

ammonia contributes) is of significant 

concern 11 and to a 2003 direction to 

policy-makers from the North American 

Research Strategy for Tropospheric 

Ozone (NARSTO) 12 indicating that 

consideration of control strategies needs 

to include ammonia in combination 

with other precursors to particle 

formation. Many commenters also 

argued that EPA should encourage or 

allow the States to consider ammonia in 

their visibility protection plans, and 

noted that ammonia reductions could be 

a cost-effective way to improve visibility 

under certain conditions.

Volatile Organic Compounds (VOCs).

Several commenters responded to our 

request for comments on whether States 

should treat VOCs in urban areas 

differently from VOCs in rural areas. 

Environmental groups and a few States 

argued that the current state of scientific 

knowledge does not support a 

differentiation between urban and rural 

sources of VOCs. One environmental 

commenter cited evidence that organic 

aerosols are a major constituent of 

visibility-reducing aerosols and that 

VOCs are important precursors to the 

formation of secondary organic aerosols. 

One commenter also stated that VOCs 

may play a particularly significant role 

in particle formation in those rural areas 

with significant nearby sources of NOX. 

Commenters also cited evidence that the 

contribution of VOC to particle 

formation likely varies widely in 

different areas of the country, and 

argued that States should retain 

flexibility to address local VOC sources 

if they determine that those sources are 

contributors of concern. 

Several industry commenters stated 

that more focus should be placed on 

controlling VOCs in urban rather than 

rural areas. A few commenters from 

industry argued that VOCs in rural areas 

have not been shown to be a significant 

contributor to particle formation, and 

should be excluded from the list of 

pollutants to be addressed in the BART 

process. One argued that VOCs should 

be excluded from BART entirely based 

upon uncertainties in the current state 

of knowledge, and a few argued that 

VOCs from both power plants and rural 

sources should be excluded from BART, 

based on low emissions and the cost of 

controls. One regional planning 

organization requested that EPA clarify 

the definitions of ‘‘urban’’ and ‘‘rural’’

areas. 

Final rule. PM10 as an indicator. 

While it is always necessary to assess 

PM2.5 impacts, we agree with 

commenters who stated that the coarse 

fraction is less efficient at light 

scattering than fine particles, there is 

ample evidence that the coarse fraction 

does contribute to visibility 

impairment.13 For example, standard 

methods for calculating reconstructed 

light extinction routinely include a 

calculation for the contribution to light 

extinction from the coarse fraction, an 

implicit recognition that these particles 

contribute measurably to visibility 

impairment.14 We do recognize that 

coarse PM is likely to contribute more 

to regional haze in arid areas than 

humid areas. We believe that, as the 

Grand Canyon Visibility Transport 

Commission (GCTVC) recognized,15

States in the arid West in particular 

should take the coarse fraction of 

particulate matter into account in 

determining whether a source meets the 

threshold for BART applicability.

Because long-range transport of fine 

particles is of particular concern in the 

formation of regional haze, we also 

39114 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

16 Fine particles: Overview of Source Testing 

Approaches, Memorandum to Docket OAR 2002–

0076, April 1, 2005.

17See Fine particles: Overview of Atmospheric 

Chemistry, Sources of Emissions, and Ambient 

Monitoring Data, Memorandum to Docket OAR 

2002–0076, April 1, 2005. 18 Ibid. 19 Ibid.

believe that it is very important to 

estimate the PM2.5 fraction of direct 

particulate emissions as correctly as 

possible. In addition, we believe that air 

quality modeling results will be more 

meaningful provide a more accurate 

prediction of a source’s impact on 

visibility if the inputs account for the 

relative particle size of directly emitted 

particulate matter (e.g. PM10 vs. PM2.5).

States should consider whether their 

current test methods for measuring 

particulate matter emissions from 

stationary sources account for the 

condensible fraction of particulate 

matter and consider revising any such 

stationary source test methods to 

account for the condensible fraction of 

particulate emissions. See the source 

testing technical support document 

(TSD) in the docket for this rule, which 

discusses test methods for particulate 

matter in more detail.16

Ammonia. In regard to ammonia, we 

believe there is sufficient uncertainty 

about emission inventories and about 

the potential efficacy of control 

measures from location to location such 

that the most appropriate approach for 

States to take is a case-by-case approach. 

There are scientific data illustrating that 

ammonia in the atmosphere can be a 

precursor to the formation of particles 

such as ammonium sulfate and 

ammonium nitrate; 17 however, it is less 

clear whether a reduction in ammonia 

emissions in a given location would 

result in a reduction in particles in the 

atmosphere and a concomitant 

improvement in visibility. In other 

words, the question of whether 

ammonia contribute to visibility 

impairment in a specific instance can be 

a difficult one.

It may be that States will not be faced 

often with the question of addressing 

ammonia in making BART 

determinations. As noted above, States 

are required to make BART 

determinations only for stationary 

sources that fall within certain 

industrial categories. The types of 

sources subject to the BART provisions 

are not typically significant emitters of 

ammonia. Because of this, it is unlikely 

that including ammonia on the list of 

visibility-impairing pollutants in the 

BART guidelines would have much 

impact on the States’ determinations of 

whether a source is BART-eligible. 

Thus, while ammonia can contribute to 

visibility impairment, we believe the 

decision whether to consider ammonia 

as a visibility-impairing pollutant in a 

specific case where a potential BART 

source actually emits more than 250 

tons per year of ammonia is best left to 

the State. 

VOCs. Organic compounds can be 

categorized according to their varying 

degrees of volatility: highly reactive, 

volatile compounds with six or fewer 

carbon atoms which indirectly 

contribute to PM formation through the 

formation of oxidizing compounds such 

as the hydroxyl radical and ozone; 

semivolatile compounds with between 

seven and 24 carbon atoms which can 

exist in particle form and can readily be 

oxidized to form other low volatility 

compounds; and high molecular weight 

organic compounds—those with 25 

carbon atoms or more and low vapor 

pressure—which are emitted directly as 

primary organic particles and exist 

primarily in the condensed phase at 

ambient temperatures. The latter organic 

compounds are considered to be 

primary PM2.5 emissions and not VOCs 

for BART purposes. 

Current scientific and technical 

information shows that carbonaceous 

material is a significant fraction of total 

PM2.5 mass in most areas and that 

certain aromatic VOC emissions such as 

toluene, xylene, and trimethyl-benzene 

are precursors to the formation of 

secondary organic aerosol.18 However, 

while progress has been made in 

understanding the role of VOCs in the 

formation of organic PM, this 

relationship remains complex, and 

issues such as the relative importance of 

biogenic versus anthropogenic 

emissions remain unresolved.

Therefore we believe that the best 

approach for States to follow in 

considering whether VOC emissions are 

precursors to PM2.5 formation is a caseby-case approach. States should 

consider, in particular, whether a 

source’s VOC emissions are those 

higher-carbon VOCs that are more likely 

to form secondary organic aerosols. In 

addition, given the variable contribution 

of a given amount of VOC emissions to 

PM2.5 formation, States may also wish to 

exercise discretion in considering only 

relatively larger VOC sources to be 

BART-eligible. 

After careful consideration of the 

comments, we agree with commenters 

who assert that EPA should not suggest 

a general distinction between the 

relative contributions of urban and rural 

VOC emissions to particle formation. 

The state of knowledge in this area is 

complex and rapidly evolving. 

Monitoring data in the East 19 suggest 

that there may be a greater contribution 

to particle formation in urban areas from 

VOCs as compared to rural areas, but we 

recognize that further research is needed 

to better determine the extent of the 

contribution of specific VOC 

compounds to organic PM mass. We do 

not agree, however, with commenters 

who make the blanket assertion that 

rural VOCs are not a significant 

contributor to particle formation, as it is 

possible that in specific areas, such as 

where NOX emissions are high, rural 

anthropogenic VOCs could potentially 

play a significant role.

Discussion of the Term ‘‘Potential’’

Emissions

Comments. A number of commenters 

were critical of the restriction in the 

regional haze rule that allows States to 

credit federally enforceable limitations 

on emissions but not limitations that are 

enforceable only by States and local 

agencies. These commenters believed 

that this restriction had been rejected by 

the D.C. Circuit for a number of other 

EPA regulations and noted that EPA has 

developed policies that currently credit 

state-enforceable limits. The comments 

recommended that EPA issue guidance 

consistent with what commenters 

claimed were current policies for other 

regulations. In addition, we received 

comments arguing that in determining 

whether a source is a major stationary 

source, the States should consider a 

source’s actual—rather than potential—

emissions. These commenters stated 

that using a source’s potential emissions 

overstates a source’s actual emissions 

and impacts on visibility. 

Final rule. CAA section 169A(g)(7) 

defines a ‘‘major stationary source’’ as a 

source with the potential to emit 250 

tons or more any pollutant. Based inter 

alia on that statutory definition, EPA’s 

implementing regulations define BARTeligible sources as those with the 

potential to emit 250 tons or more of 

any air pollutant. As these definitions 

clearly require consideration of a 

source’s potential emissions, the 

guidelines state that a State should 

determine whether a source’s potential 

emissions exceed the 250 ton threshold 

in determining whether the source is 

BART-eligible. 

As explained in the 2001 and 2004 

proposed guidelines, the regional haze 

regulations define ‘‘potential to emit.’’

The guidelines repeat that regulatory 

definition and provide an example 

illustrating its application. EPA did not 

propose to change the definition in 2001 

or 2004, but merely highlighted the 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39115

current definition in 40 CFR 51.301. 

Although we noted in the 2001 

proposed guidelines that we expected to 

undertake a rulemaking to determine 

whether only federally enforceable 

limitations should be taken into account 

in the regional haze program definition, 

we have not yet begun the process for 

such a rulemaking. However, we 

consider the comments criticizing EPA’s 

definition of ‘‘potential to emit’’ as a 

request for reconsideration of the 

visibility regulations and will take these 

requests into account in determining 

any future rulemaking efforts to address 

the general definition of ‘‘potential to 

emit.’’ For the time being, we believe 

that States may consider federally 

enforceable limits or emissions 

limitations in State permits, which are 

enforceable under State law, in 

determining a source’s ‘‘potential to 

emit.’’

Discussion of What Emissions Units 

Should Be Considered Part of a 

‘‘Stationary Source’’

Comments. A number of comments in 

2001 expressed concern with our 

statement that a ‘‘support facility’’

should be grouped with a primary 

facility in determining which emissions 

units belong to the same industrial 

grouping. These comments generally 

coincided with comments discussed 

above that EPA should determine BART 

on a plantwide basis, rather than by 

aggregating emissions units. 

Commenters on the 2004 reproposal 

noted with approval the clarification 

that ‘‘support facilities’’ should only be 

considered BART-eligible if these units 

themselves were both constructed 

within the 1962–1977 time frame and 

fell within one of the listed source 

categories. 

Two commenters felt that we should 

more clearly define the BART-eligible 

source, either by identifying emission 

units within source categories, or by 

somehow accounting for the specific set 

of emission units, within the fenceline, 

to which controls would logically apply. 

Final rule. The guidelines continue to 

note that the definition of ‘‘building, 

structure or facility’’ in the regional 

haze rule is based upon aggregating 

emissions units within the same 

industrial grouping. This discussion in 

the guidelines is consistent with the 

language in the definition of ‘‘building, 

structure or facility’’ in the regional 

haze rule which contains a specific 

reference to the 2-digit SIC 

classifications. The BART guidelines 

refer to this definition and explain how 

2-digit SIC codes are used in 

determining the scope of BART for a 

given plantsite. (In the rare situation 

where industrial groupings in separate 

2-digit SIC codes exist at a single plant 

site, then there would be more than one 

separate ‘‘stationary source’’ present. In 

that situation, each ‘‘stationary source’’

should be looked at individually for 

purposes of determining BARTeligibility.) 

We agree that more clarity is needed 

to account for situations where a 

specific set of units constitute the 

logical set to which BART controls 

would apply. The CAA requires BART 

at certain major stationary sources. 

Accordingly we believe it could be 

appropriate, at the BART determination 

step, for States to allow sources to 

‘‘average’’ emissions across a set of 

BART-eligible emission units within a 

fenceline, so long as the amount of 

emission reductions from each pollutant 

being controlled for BART would be at 

least equal to those reductions that 

would be obtained by simply 

controlling each unit. We have added 

language to the guidelines to this effect. 

Step 4: Identify the Emission Units and 

Pollutants That Constitute the BARTEligible Source

Background. The final step in 

identifying a ‘‘BART-eligible source’’ is 

to use the information from the previous 

three steps to identify the universe of 

equipment that makes up the BARTeligible source. The 2001 and 2004 

proposed BART guidelines stated that 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 individual visibility-impairing 

pollutant, then that collection of 

emissions units is a BART-eligible 

source. The guidelines also stated that a 

BART analysis would be required for 

each visibility-impairing pollutant 

emitted from this collection of 

emissions units. 

In the 2004 reproposed BART 

guidelines, we noted that we believed 

that section 169A(b)(2)(A) of the CAA 

requires a State to undertake a BART 

analysis for ‘‘any’’ visibility-impairing 

pollutant emitted by a BART-eligible 

source, regardless of the amount 

emitted. We proposed, however, to 

provide the States with the flexibility to 

identify de minimis levels for pollutants 

at BART-eligible sources, but limited 

that flexibility so that any such de 

minimis levels could not be higher than 

those used in the PSD program: 40 tons 

per year for SO2, NOX, and VOC, and 15 

tons per year from PM10. We requested 

comment on this provision and on the 

use of de minimis values. 

Discussion of Whether To Include All 

Emitted Visibility-Impairing Pollutants 

in the BART Analysis 

Comments. A number of commenters 

supported the concept of including all 

pollutants in the BART analysis once an 

individual pollutant triggers the BART 

review. Other commenters, although 

supportive of the concept generally, 

recommended that we should add the 

pollutants together before the 

comparison with the threshold. 

A number of commenters disagreed 

with EPA’s conclusion that the CAA 

requires States to make a BART 

determination for any visibilityimpairing air pollutant emitted by a 

BART eligible source. These 

commenters stated that undertaking a 

BART analysis for all pollutants emitted 

by a major stationary source is an 

unnecessary administrative burden with 

minimal environmental benefit. 

Commenters argued that Congress 

intended for BART to apply only to 

those pollutants for which a source is 

major. Commenters accordingly 

recommended that the 250 ton per year 

threshold apply to each pollutant 

emitted by a source and that BART 

apply only to those pollutants which 

meet this threshold. A number of these 

commenters argued alternatively that 

only those pollutants from a source 

demonstrated, individually, to cause or 

contribute to visibility impairment are 

required to go through a BART 

determination. 

Final rule. We disagree with the 

comment that emissions of different 

visibility-impairing pollutants must be 

added together to determine whether a 

source exceeds the 250 ton per year 

threshold. The CAA, in section 

169A(g)(7), defines a ‘‘major stationary 

source’’ as one with the potential to 

emit 250 tons or more of ‘‘any 

pollutant.’’

We disagree with comments that the 

BART analysis is required only for those 

pollutants that individually exceed the 

250 ton per year threshold. Section 

169A(b)(2)(A) specifically requires 

States to submit SIPs that include a 

requirement that a major stationary 

source

which, as determined by the State * * * 

emits any air pollutant which may 

reasonably be anticipated to cause or 

contribute to any impairment of visibility in 

any [Class I area], shall procure, install, and 

operate * * * the best available retrofit 

technology, as determined by the State * * * 

for controlling emissions from such source 

for the purpose of eliminating or reducing 

any such impairment.

The regional haze regulations similarly 

require that the States submit a SIP that 

contains

39116 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

20EDF et al. v. EPA, 82 F.3d 451, 466 (D.C. Cir. 

1996) citing Alabama Power v. Costle, 636 F.2d 323 

(D.C. Cir. 1979).

21 Id.

A determination of BART for each BARTeligible source in the State that emits any air 

pollutant which may reasonably be 

anticipated to cause or contribute to any 

impairment of visibility in any mandatory 

Class I Federal area.

40 CFR 51.308(e)(1)(ii). Nothing in these 

statutory or regulatory requirement 

suggests that the BART analysis is 

limited to those pollutants for which a 

source is considered major. At best, 

these provisions can be read as 

requiring a BART determination only 

for those emissions from a specific 

source which do, in fact, cause or 

contribute to visibility impairment in a 

particular Class I area, or which could 

reasonably be anticipated to do so. 

Commenters, however, have not 

presented any evidence that as a general 

matter emissions of less than 250 tons 

per year of PM2.5, SO2, or other 

visibility-impairing pollutants from 

potential BART sources do not ‘‘cause 

or contribute to any impairment of 

visibility’’ in any of the Class I areas 

covered by the regional haze rule. As 

there is no such evidence currently 

before us, there is no basis to conclude 

that the States are required to make 

BART determinations only for those 

pollutants emitted in excess of 250 tons 

per year. 

At the same time, we agree with 

certain commenters that the CAA does 

not require a BART determination for 

any visibility impairing pollutant 

emitted by a source, regardless of the 

amount. After reviewing the language of 

the Act and the comments received, we 

have concluded that our interpretation 

of the relevant language in section 

169A(b)(2)(A) of the Act in the 2004 

proposed guidelines is not necessarily 

the best reading of the BART provisions. 

Section 169A(b)(2)(A) of the Act can be 

read to require the States to make a 

determination as to the appropriate 

level of BART controls, if any, for 

emissions of any visibility impairing 

pollutant from a source. Given the 

overall context of this provision, 

however, and that the purpose of the 

BART provision is to eliminate or 

reduce visibility impairment, it is 

reasonable to read the statute as 

requiring a BART determination only 

for those emissions from a source which 

are first determined to contribute to 

visibility impairment in a Class I area. 

The interpretation of the requirements 

of the regional haze program reflected in 

the discussion above does not 

necessitate costly and time-consuming 

analyses. Consistent with the CAA and 

the implementing regulations, States 

can adopt a more streamlined approach 

to making BART determinations where 

appropriate. Although BART 

determinations are based on the totality 

of circumstances in a given situation, 

such as the distance of the source from 

a Class I area, the type and amount of 

pollutant at issue, and the availability 

and cost of controls, it is clear that in 

some situations, one or more factors will 

clearly suggest an outcome. Thus, for 

example, a State need not undertake an 

exhaustive analysis of a source’s impact 

on visibility resulting from relatively 

minor emissions of a pollutant where it 

is clear that controls would be costly 

and any improvements in visibility 

resulting from reductions in emissions 

of that pollutant would be negligible. In 

a scenario, for example, where a source 

emits thousands of tons of SO2 but less 

than one hundred tons of NOX, the State 

could easily conclude that requiring 

expensive controls to reduce NOX

would not be appropriate. In another 

situation, however, inexpensive NOX

controls might be available and a State 

might reasonably conclude that NOX

controls were justified as a means to 

improve visibility despite the fact that 

the source emits less than one hundred 

tons of the pollutant. Moreover, as 

discussed below, we are revising the 

regional haze regulations to allow the 

States to exempt de minimis emissions 

of SO2, NOX, and PM2.5 from the BART 

determination process which should 

help to address the concerns of certain 

commenters associated with the burden 

of a broad BART analysis. 

De minimis levels 

Comments. Many commenters agreed 

that we should establish de minimis

levels for individual pollutants in order 

to allow States and sources to avoid 

BART determinations for pollutants 

emitted in relatively trivial amounts. 

Many commenters suggested that States 

would be unlikely to impose emission 

limits for pollutants emitted at the 

proposed de minimis levels because it 

would not be cost-effective to do so and 

such emission reductions could not be 

expected to produce any perceptible 

improvements in visibility. Several 

commenters agreed that the pollutant 

coverage requirements for BART 

eligibility should be consistent with 

those for the PSD program, but others 

argued that BART should be required 

only for pollutants emitted in amounts 

greater than 250 tons per year. 

Commenters also noted that the 

guidelines were not clear as to whether 

the de minimis provision would apply 

on a plant-wide or unit by unit basis. A 

few commenters also noted that the 

final guidelines should clarify where in 

the BART determination process de 

minimis levels may be used. 

Other commenters opposed the use of 

de minimis exemptions. These 

commenters argued that it would be 

unreasonable to rule categorically that a 

certain level of emissions had a trivial 

impact on visibility without assessing 

the impacts of these emissions in 

particular circumstances. These 

commenters argued that States should 

consider the emissions of all visibilityimpairing pollutants in a BART 

determination regardless and that, 

consequently, there should be no de 

minimis levels. 

Final rule. As proposed in 2004, we 

believe that it is reasonable to give 

States the flexibility to establish de 

minimis levels so as to allow them to 

exempt from the BART determination 

process pollutants emitted at very low 

levels from BART-eligible sources. As 

explained by the D.C. Circuit, 

‘‘categorical exemptions from the 

requirements of a statute may be 

permissible ‘as an exercise of agency 

power, inherent in most statutory 

schemes, to overlook circumstances that 

in context may fairly be considered de 

minimis.’ ’’ 20 The ability to create de 

minimis exemptions from a statute is a 

tool to be used in implementing the 

legislative design.21

The intent of Congress in requiring 

controls on emissions from certain 

major stationary sources was to 

eliminate or reduce any anticipated 

contribution to visibility impairment 

from these sources. This, as section 

169A(b)(2)(A) states, is the ‘‘purpose’’ of 

BART. In making a determination as to 

the appropriate level of controls, 

however, the States are required to take 

into account not only the visibility 

benefits resulting from imposing 

controls on these sources but also the 

costs of complying with the BART 

provision. The BART provision is 

accordingly designed to ensure that the 

States take into consideration all 

emissions of certain stationary sources 

in making a BART determination, but 

also to provide States with the 

flexibility to include the costs and 

benefits of controlling these sources in 

the calculus of determining the 

appropriate level of BART.

We believe it would be permissible 

for States to create de minimis levels at 

a low level. If a State were to undertake 

a BART analysis for emissions of less 

than 40 tons of SO2 or NOX or 15 tons 

of PM10 from a source, it is unlikely to 

result in anything but a trivial 

improvement in visibility. This is 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39117

because reducing emissions at these 

levels would have little effect on 

regional emissions loadings or visibility 

impairment. We believe most States 

would be unlikely to find that the costs 

of controlling a few tons of emissions 

were justified. Because the overall 

benefits to visibility of requiring BART 

determinations for emissions of less 

than the de minimis levels would be 

trivial, we are amending the regional 

haze rule to make clear that the States 

have this flexibility. 

The de minimis levels discussed 

today apply on a plant-wide basis. 

Applying de minimis levels on a unit by 

unit basis as suggested by certain 

commenters could exempt hundreds of 

tons of emissions of a visibilityimpairing pollutant from BART 

analysis. In at least some of the twentysix source categories covered by the 

BART provisions, a single control 

device can be used to control emissions 

from multiple units. Thus, it is possible 

that while emissions from each unit are 

relatively trivial, the costs of controlling 

emissions from multiple units might be 

cost-effective in light of the BARTeligible source’s total emissions of the 

pollutant at issue. States should 

consider the control options in such 

situations and determine the 

appropriate approach for the specific 

source. 

We are revising the regional haze rule 

to provide States with the ability to 

establish de minimis levels up to the 

levels proposed in 2004. We believe 

States may, if they choose, exclude from 

the BART determination process 

potential emissions from a source of less 

than forty tons per year of SO2 or NOX, 

or 15 tons per year for PM10. (Note also 

that for sources that are BART-eligible 

for one pollutant, we also believe that 

States could allow those sources to 

model the visibility impacts of 

pollutants at levels between de minimis

and 250 tons in order to show that the 

impact is negligible and should be 

disregarded. See section D below). In 

the guidelines, we include this as part 

of the BART determination in section IV 

of the guidelines. (We note that these 

emission levels represent the maximum 

allowable de minimis thresholds—

States retain their discretion to set the 

thresholds at lesser amounts of each 

pollutant, or to not provide any predetermined de mininis levels.) We 

believe that this approach is the clearest 

method for exempting trivial emissions 

from the BART determination process. 

Alternatively, States may find it useful 

to exclude de minimis emissions in 

identifying whether a source is subject 

to BART in section III of the guidelines. 

Either approach is consistent with the 

regulation issued in this rule. 

D. How To Determine Which BARTeligible Sources Are ‘‘Subject to BART’’

Cause or Contribute 

Background. Under section 

169A(b)(2)(A) of the Act, each State 

must review its BART eligible sources 

and determine whether they emit ‘‘any 

air pollutant which may reasonably be 

anticipated to cause or contribute to any 

impairment of visibility in [a Class I] 

area.’’ If a source meets this threshold, 

the State must then determine what is 

BART for that source. 

Proposed rule. In the reproposed 

guidelines, we identified three options 

for States to use in determining which 

BART-eligible sources meet the test set 

forth in section 169A(b)(2)(A) of the 

CAA. To determine whether a BARTeligible source is ‘‘reasonably 

anticipated to cause or contribute to 

visibility impairment,’’ the first 

proposed option was that a State could 

choose to consider the collective 

contribution of emissions from all 

BART-eligible sources and conclude 

that all BART-eligible sources within 

the State are ‘‘reasonably anticipated to 

cause or contribute’’ to some degree of 

visibility impairment in a Class I area. 

The preamble to the 1999 regional haze 

rule explains at length why we believe 

that looking to the collective 

contribution of many sources over a 

broad area is a reasonable approach, and 

we explained in the 2004 reproposed 

guideline that we believed that a State’s 

decision to use a cumulative analysis at 

this stage of the BART determination 

process would be consistent with the 

CAA and the findings of the D.C. Circuit 

in American Corn Growers.

The second proposed option was to 

allow a State to demonstrate, using a 

cumulative approach, that none of its 

BART-eligible sources contribute to 

visibility impairment. Specifically, we 

proposed to provide States with the 

option of performing an analysis to 

show that the full group of BARTeligible sources in a State cumulatively 

do not cause or contribute to visibility 

impairment in any Class I areas. 

As a third option, we proposed that a 

State may choose to determine which 

sources are subject to BART based on an 

analysis of each BART-eligible source’s 

individual contribution. We labeled this 

option as an ‘‘Individualized Source 

Exemption Process,’’ and proposed that 

States use an air quality model to 

determine an individual source’s 

contribution to visibility impairment, 

calculated on a 24 hour basis, using 

allowable emissions, and compared to 

an established threshold. 

Comments. Several commenters 

expressed the view that EPA was 

misinterpreting the American Corn 

Growers case to allow the States to 

apply a collective contribution test in 

determining whether BART-eligible 

sources are subject to BART. These 

commenters took the position that, 

because this approach does not allow 

for a source to show that it does not 

individually cause or contribute to 

visibility impairment, it is incompatible 

with the language of section 

169A(b)(2)(A)of the Act. They argued 

that EPA should modify the provisions 

in the proposed rule to ensure that an 

individual source is afforded the 

opportunity to conduct an analysis to 

demonstrate that its emissions do not 

impair visibility in any Class I area. 

Conversely, several commenters 

indicated that the option to determine 

that all potential BART sources 

contribute to regional haze should be 

the starting point of determining BART 

eligibility. 

Many industry commenters and some 

States supported the second proposed 

option which would allow a State to 

demonstrate through an analysis of the 

collective contribution of all its BARTeligible sources that none of these 

sources contribute to visibility 

impairment. Several of these 

commenters added, however, that if this 

cumulative analysis were to show a 

contribution, then, consistent with the 

decision in American Corn Growers, the 

State must allow each individual source 

to demonstrate that its own emissions 

do not, by themselves, contribute to the 

problem of visibility impairment. One 

commenter requested clarification on 

what visibility threshold a State should 

use in determining that no sources are 

reasonably anticipated to cause or 

contribute to any impairment in a Class 

I area.

A number of commenters supported 

the third option for determining BART 

applicability based on an analysis of 

source-specific effects on visibility. 

However, many of the commenters 

stated that the CAA requires that the 

States either conduct such an analysis 

in determining those sources subject to 

BART, or allow an individual source to 

make a showing that it does not cause 

or contribute to visibility impairment. In 

addition, although supportive of the 

general notion of allowing for an 

exemption process for BART-eligible 

sources, several commenters stated that 

the third option contained burdensome 

modeling requirements, and that States 

need a more flexible, straightforward, 

39118 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

22States choosing this approach should use the 

data being developed by the regional planning 

organizations, or on their own, as part of the 

regional haze SIP development process to make the 

showing that the State contributes to visibility 

impairment in one or more Class I areas.

23 Grand Canyon Visibility Transport 

Commission, Recommendations for Improving 

Western Vistas, Report to the U.S. EPA, June 10, 

1996.

and less costly method to make the 

‘‘cause or contribute’’ determination. 

Several environmental groups 

commented that the proposed options 

potentially go too far in allowing 

sources to be exempted from the BART 

requirements. These commenters 

asserted that EPA should clarify that 

States may not allow a BART-eligible 

source to avoid the BART requirements 

without an affirmative demonstration by 

the State, or by the source, showing that 

the source does not emit any air 

pollutant which may reasonably be 

anticipated to cause or contribute to any 

impairment of visibility in a Class I area. 

Absent such a demonstration, they 

argue, a State may not choose to waive 

the requirement to conduct a BART 

review of the source. 

Final rule. The final BART guidelines 

adopt the general approach contained in 

the reproposal, providing the States 

with several options for identifying the 

sources subject to BART. The final 

BART guidelines describe the options 

contained in the reproposal as well as 

one new option. The discussion of 

options in the final guidelines are 

structured somewhat differently from 

the reproposal, and the options are 

explained in greater detail. The 

guidelines reaffirm that a State may 

choose to consider all BART-eligible 

sources to be subject to BART, and to 

make BART determinations for all its 

BART-eligible sources.22 For States that 

choose to consider exempting some or 

all of their BART-eligible sources from 

review, the guidelines then discuss 

three options that States may use to 

determine whether its sources are 

‘‘reasonably anticipated to cause or 

contribute’’ to visibility impairment at a 

Class I area. Options 1 and 3 are similar 

to options in the 2004 reproposal; under 

option 1, States may use an individual 

source attribution approach, while 

option 3 provides the States with an 

approach for demonstrating that no 

sources in a State should be subject to 

BART. Option 2 is new; it is an 

approach for using model plants to 

exempt individual sources with 

common characteristics.

Threshold for visibility impact. One of 

the first steps in determining whether 

sources cause or contribute to visibility 

impairment for purposes of BART is to 

establish a threshold (quantified in units 

called ‘‘deciviews’’) against which to 

measure the visibility impact of one or 

more sources. We believe that 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. 

The guidelines note that 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. 

Although the appropriate threshold may 

vary, the Guidelines state that the 

contribution threshold used for BART 

applicability should not be higher than 

0.5 deciviews. We discuss threshold 

issues in greater detail in the subsection 

immediately following this one, entitled 

Metric for Visibility Degradation.

Pollutants 

The guidelines direct that States 

should 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 BART-eligible sources, 

States do not need to consider less than 

de minimis emissions of these 

pollutants from a source. 

States may use their best judgement to 

determine whether VOC or ammonia 

emissions are likely to have an impact 

on visibility in an area. In addition, they 

may use PM10 or PM2.5 as an indicator 

for PM2.5 in determining whether a 

source is subject to BART. In 

determining whether a source 

contributes to visibility impairment, 

however, States 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).

We believe that PM10 is likely to 

contribute more to regional haze in arid 

areas than humid areas. As the Grand 

Canyon Visibility Transport 

Commission (GCTVC) recognized,23

States in the arid West, in particular, 

will need to take the coarse fraction of 

particulate matter into account in 

determining whether a source meets the 

threshold for BART applicability.

Option 1. We agree with commenters 

supporting the use of an individual 

source analysis in determining if a 

BART-eligible source causes or 

contributes to visibility impairment. 

Consistent with American Corn 

Growers, this option provides a method 

for a State to evaluate the visibility 

impact from an individual source and 

show that the source is not reasonably 

anticipated to cause or contribute to 

visibility degradation in a Class I area 

and thus may be exempt from BART. 

(Note also that an individual source 

analysis is used to inform the BART 

determination). In general, a dispersion 

model is used to assess the visibility 

impact from a single source, and that 

impact is compared to a threshold 

which is determined by the State. The 

threshold (quantified in deciviews) is 

the numerical metric that is used to 

define ‘‘cause or contribute’’; if a 

source’s impact is below the threshold, 

a State may exempt the source from 

BART; otherwise the source would be 

subject to BART. 

We discuss specific issues on the 

individualized source attribution 

process, including changes since 

proposal and issues raised by 

commenters, in the subsections 

immediately following this one: Metric 

for visibility degradation; Use of 

CALPUFF for visibility modeling; The 

use of natural conditions in determining 

visibility impacts for reasonable 

progress and comparison to threshold 

values; Modeling protocol; and 

Alternatives for determining visibility 

impacts from individual sources. 

Option 2. In the final guideline, we 

describe a modified approach, using 

model plants based on representative 

sources sharing certain characteristics, 

that the States may use to simplify the 

BART determination process, either to 

exempt (individually or as a group) 

those small sources that are not 

reasonably anticipated to cause or 

contribute to visibility impairment, or to 

identify those large sources that clearly 

should be subject to BART review. 

States could use the CALPUFF model, 

for example, to estimate levels of 

visibility impairment associated with 

different combinations of emissions and 

distances to the nearest Class I area. In 

carrying out this approach, the State 

could then reflect groupings of specific 

types of sources with important 

common characteristics, such as 

emissions, stack heights and plume 

characteristics, and develop ‘‘composite 

model plants.’’ Based on CALPUFF 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39119

24Supplement to 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.

25CALPUFF 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.

26For regional haze applications, regional scale 

modeling typically involves use of a photochemical 

grid model that is capable of simulating aerosol 

chemistry, transport, and deposition of airborne 

pollutants, including particulate matter and ozone. 

Regional scale air quality models are generally 

applied for geographic scales ranging from a multistate to the continental scale. Because of the design 

and intended applications of grid models, they may 

not be appropriate for BART assessments, so States 

should consult with the appropriate EPA Regional 

Office prior to carrying out any such modeling.

27 Guidance for Estimating Natural Visibility 

Conditions Under the Regional Haze Rule, (U.S. 

Environmental Protection Agency, September 2003. 

http://www.epa.gov/ttncaaa1/t1/memoranda/

rh_envcurhr_gd.pdf. Natural background 

conditions, expressed in deciviews, are defined for 

each Class I area. EPA has issued guidance for 

estimating natural background conditions which 

has estimates of default conditions as well as 

measures to develop refined estimates of natural 

conditions.

28 In the proposal we noted that a 0.5 deciview 

change in visibility is linked to ‘‘perceptibility,’’ or 

Continued

analyses of these model plants, a State 

may find that certain types of sources 

are clearly reasonably anticipated to 

cause or contribute to visibility 

impairment. Conversely, representative 

plant analyses may show that certain 

types of sources are not reasonably 

anticipated to cause or contribute to 

visibility impairment. Based on the 

modeling results, a State could exempt 

from BART all sources that emit less 

than a certain amount per year and that 

are located a certain distance from the 

nearest Class I area. 

Our analyses of visibility impacts 

from model plants provide a useful 

example of the type of analyses that 

might be used to exempt categories of 

sources from BART.24 Based on our 

model plant analysis, EPA believes that 

a State could reasonably choose to 

exempt sources that emit less than 500 

tons per year of NOX or SO2 (or 

combined NOX and SO2), as long as they 

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.

In our analysis, we developed two 

model plants (a EGU and a non-EGU), 

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). Because 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 

may be instructive in the development 

of an exemption process for groups of 

BART-eligible sources, without 

modeling each of these sources 

individually. 

States may want to conduct their own 

model plant analysis that take into 

account local, regional, and other 

relevant factors (such as meteorology, 

sulfur dioxide, nitrogen dioxide, and 

ammonia). If so, you may want to 

consult your EPA Regional Office to 

ensure that any relevant technical issues 

are resolved before you conduct your 

modeling.

In preparing our hypothetical 

examples, 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 impacts, 

while others may understate the 

modeling results. On balance, when all 

of these factors are considered, we 

believe that our examples reflect 

realistic treatments of the situations 

being modeled.25 A summary of the 

more significant elements and their 

implications is provided below.

Features of the modeling examples 

which may understate visibility impacts 

• An annual emission rate was used 

for the example modeling (e.g. 10,000 

TPY divided by 365 days divided by 24 

hours). ‘‘Real world’’ sources have 

variable emission rates, and in any 24 

hour period may be operating well 

above the annual rate. 

• The monthly average relative 

humidity was used, rather than the 

daily average humidity, and would 

contribute to lowering the peak values 

in daily model averages. 

• A 24-hour average was calculated 

from modeled hourly visibility impacts, 

reducing the impact of any one 

particular hour that could be higher due 

to a number of meteorological effects. 

Features of the modeling examples 

which may overstate visibility impacts 

• We located receptors using a grid of 

concentric circles for distances of 50, 

100 and 200 km. A receptor was placed 

every 10 degrees around each circle, and 

highest impacts were reported 

regardless of direction from the source. 

In actuality, receptors would be located 

only in the Class I area, or in only one 

direction from the source. 

• We used simplified chemistry (i.e.

for conversion of SO2 and NOX to fine 

particles) and disperson techniques 

which tend to overstate model impacts. 

Special care should be used to ensure 

that the criteria used in the modeling 

are appropriate for a given State. Our 

modeling may not be appropriate for 

every region of the country, due to the 

unique characteristics of different Class 

I areas and varying meteorological and 

geographical conditions in different 

regions. In addition, States may want to 

design their own model plants taking 

into account the types of sources at 

issue in their region. 

Option 3. Under the BART guidelines, 

a State may consider exempting all its 

BART-eligible sources from BART by 

conducting analyses that show that all 

of the emissions from BART-eligible 

sources in their State, taken together, are 

not reasonably anticipated to cause or 

contribute visibility impairment. To 

make such a showing, a State could use 

CALPUFF or another appropriate 

dispersion model to evaluate the 

impacts of individual sources on 

downwind Class I areas, aggregating 

those impacts to determine the 

collective contribution from all-BART 

eligible sources in the State. A State 

with a sufficiently large number of 

BART-eligible sources could also make 

such a showing using a photochemical 

grid model.26

We agree with commenters who 

pointed out that the option of allowing 

a State to demonstrate that the full 

group of BART-eligible sources in the 

State do not contribute to visibility 

impairment would, by default, satisfy an 

individual source contribution 

assessment. Commenters have not 

shown any reason to believe that if the 

sum total of emissions from the BARTeligible sources in a State do not ‘‘cause 

or contribute’’ to visibility impairment 

in any Class I area, that emissions from 

one such source will meet the threshold 

for BART applicability. A State 

following this approach accordingly 

need not undertake an affirmative 

demonstration based on a source by 

source analysis of visibility impacts to 

find that its sources are not subject to 

BART.

Metric for Visibility Degradation 

Background. The 2004 reproposed 

guidelines contained a proposed 

threshold for the States to use in 

determining whether an individual 

source could be considered to cause 

visibility impairment in a Class I area. 

We proposed a 0.5 deciview change 

relative to natural background 

conditions,27 as a numerical threshold 

for making this determination.28

39120 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

a just noticeable change in most landscapes. 

National Acid Precipitation Assessment Program 

(NAPAP), Acid Deposition: State of Science and 

Technology Report 24, Visibility: Existing and 

Historical Conditions—Causes and Effects 

(Washington, DC, 1991) Appendix D at 24–D2 

(‘‘changes in light extinction of 5 percent will evoke 

a just noticeable change in most landscapes’’). 

Converting a 5 percent change in light extinction to 

a change in deciviews yields a change of 

approximately 0.5 deciviews.

29 Ibid.

30Henry, R.C., Just-Noticeable Differences in 

Atmospheric Haze, Journal of the Air & Waste 

Management Association, 52:1238–1243, October 

2002.

31Moreover, the fact that the ultimate purpose of 

the visibility provisions is expressed as a ‘‘goal’’

does not mean that all aspects of the program are 

merely aspirational. CAA section 169A(a)(4) 

requires EPA to establish regulations to ensure that 

reasonable progress is made toward the national 

visibility goal, and 169A(b)(2) provides that EPA 

must require SIPs to contain emission limits, 

schedules of compliance, and other measures as 

may be necessary to make reasonable progress 

towards meeting the goal.

32 If ‘‘causing’’ visibility impairment means 

causing a humanly perceptible change in visibility 

in virtually all situations (i.e. a 1.0 deciview 

change), then ‘‘contributing’’ to visibility 

impairment must mean having some lesser impact 

on the conditions affecting visibility that need not 

rise to the level of human perception.

We proposed the CALPUFF model as 

the preferred approach for predicting 

whether a single source caused visibility 

impairment if the modeled results 

showed impacts from the source that 

exceeded the threshold on any given 

day during a five-year period. We also 

proposed that if a source had an 

estimated impact on visibility of less 

than 0.5 deciviews, a State could choose 

to exempt the source from further BART 

analysis. 

Comments. We received numerous 

comments supporting the proposed 

threshold. A number of commenters 

stated that the 0.5 deciview threshold is 

appropriate given the low triggering 

threshold for applicability established 

by Congress, and that the literature 

supports it as the minimum level of 

perceptibility. Some commenters cited 

published documentation supporting 

their assertions that a minimum change 

in deciviews necessary for perceptibility 

is 0.5 deciviews.29

Other commenters criticized the 

threshold as too low. They stated that a 

change of 0.5 deciviews is inconsistent 

with language in the regional haze rule 

pointing to 1.0 deciview as the 

appropriate perceptibility threshold, 

and they cited more recent literature 

justifying perceptibility as greater than a 

change of 1 deciview.30

One commenter said that we should 

allow States and regional planning 

organizations (RPOs) the flexibility to 

determine appropriate visibility-impact 

thresholds in light of current knowledge 

about a range of perceptibility 

thresholds. Another commenter said 

that we should explain our basis for 

establishing a threshold of a one-time 

impact of greater than 0.5 deciviews, in 

light of the overall goal of the regional 

haze program. Yet another commenter 

said that the proposal would ‘‘change 

the regulatory role of the deciview 

metric by converting it into a regulatory 

0.5 deciview standard (versus a ‘goal’) 

for defining how States must exercise 

their authority and discretion in 

determining whether an individual 

source ‘causes or contributes’ to 

visibility impairment in a Class I area.’’

Several commenters said that the 0.5 

deciview threshold is too high. A 

recurring comment was that the 

statutory BART applicability test from 

CAA Section 169A(b)(2)(A) contains 

two separate elements: ‘‘causation’’ of 

any visibility impairment and 

‘‘contribution’’ to any such impairment. 

Commenters pointed out that by setting 

a threshold of 0.5 deciviews, we had 

combined ‘‘cause or contribute’’ into a 

single test of causality, thus effectively 

eliminating the ‘‘contribution’’ element 

of the BART applicability test. The 

commenters asserted that a single 

BART-eligible source can ‘‘contribute’’

to visibility impairment with impacts 

much lower than 0.5 deciviews. They 

argued that we must set the minimum 

threshold for individual source 

contribution to visibility impairment at 

the lowest level detectable by modeling 

or other appropriate analysis, and that 

this minimum individual contribution 

level must in any event be set at no 

greater than a 0.1 deciview change 

relative to natural conditions, which is 

a clearly measurable level. One 

commenter suggested that a cause or 

contribute threshold be set at some 

percentage of the ‘‘just noticeable’’

change of 0.5 deciviews.

Another commenter said that in a case 

where multiple sources each have a 

visibility impact of less than a 0.5 

deciview change, but together result in 

a change of more than 0.5 deciview, 

each of these sources contributes to the 

resulting visibility impairment. This 

commenter asserted that BART 

guidelines that result in exemptions for 

these ‘‘contributing’’ sources would 

subvert the goals of the regional haze 

program. 

Similarly, several commenters 

suggested that if any combination of 

BART eligible sources causes visibility 

impairment in a Class I area of more 

than 0.5 deciviews (by CALPUFF 

modeling for any 24-hour period, for 

example), that State should determine 

that each individual source is subject to 

BART. Thus, the commenter added, the 

court’s concern about the lack of 

‘‘empirical evidence of a source’s 

contribution to visibility impairment’’

would be addressed. 

Two commenters said that our 

requirement to use the maximum 24-

hour value over the 5-year period of 

meteorological data in the modeling, as 

proposed, is too stringent, unreasonable, 

inappropriate, and departs from the 

previous methodologies for the regional 

haze program. Additionally they said 

that the threshold is restrictive because 

the single highest 24-hour modeled 

impact over a three- or five-year period 

may be influenced by short-term 

weather conditions, like high humidity, 

and the BART applicability 

determination should not be made 

based on a one-time occurrence. 

One commenter said that whatever 

the final threshold for a single-source 

impact for BART sources, EPA should 

clarify that the purpose of this modeling 

assessment is to evaluate a source’s 

anticipated contribution to uniform 

regional haze over the Class I area. EPA 

should state that the assumption of a 

uniform haze contribution based on 

CALPUFF modeling eliminates the need 

to assess issues related to the size of the 

Class I area, views within a Class I area, 

and weather impact interactions. 

Finally, one commenter said that 

thresholds should be established 

separately for the eastern and western 

regions of the United States, as natural 

visibility conditions are established 

separately for eastern and western 

regions in the guidance. 

Final Rule. Today’s guidelines advise 

States to use a deciview metric in 

defining ‘‘cause or contribute,’’ as 

explained further below. The fact that 

the deciview is also used to track 

progress toward the goal of natural 

visibility does not in any way indicate 

that we are ‘‘converting’’ a ‘‘goal’’ into 

a requirement.31 Use of the same metric 

in the ‘‘cause or contribute’’ context as 

used for establishing reasonable 

progress goals, tracking changes in 

visibility conditions, and defining 

baseline, current, and natural conditions 

simply provides for a consistent 

approach to quantifying visibility 

impairment.

In response to commenters who said 

we conflated the ‘‘cause or contribute’’

test, we are clarifying that for purposes 

of determining which sources are 

subject to BART, States should consider 

a 1.0 deciview change or more from an 

individual source to ‘‘cause’’ visibility 

impairment, and a change of 0.5 

deciviews to ‘‘contribute’’ to 

impairment.32

In a regulatory context, we believe 

that a State’s decision as to an 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39121

33All states are working together in regional 

planning organizations, and we expect that states 

will have modeling information that identifies 

sources affecting visibility in individual class I 

areas, and the magnitude of their impacts.

34Under our guidelines, 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 ‘‘contribution to 

contribution’’ test.

appropriate threshold for contribution 

could depend upon the number of 

sources affecting a class I area. To 

illustrate, if there were only one 

emissions source affecting visibility in a 

class I area, that source could have a 

deciview impact only slightly below the 

perceptibility threshold without 

contributing to noticeable impairment. 

However, if there were 100 sources each 

changing visibility by 0.1 deciviews, the 

total impact would be a 10-deciview 

change in visibility. In this hypothetical 

example, all 100 sources would be 

contributing, in equal amounts, to 

substantial visibility impairment.

Because circumstances will vary in 

different locations, we believe that 

States should have discretion to set an 

appropriate threshold depending on the 

facts of the situation. We believe, 

however, that it would be difficult for a 

State to justify a threshold higher than 

0.5 deciviews. In particular, 0.5 

deciviews represents one half of the 1.0 

deciview level that we are equating with 

a single source ‘‘causing’’ visibility 

degradation. Typically, there are 

multiple sources that affect visibility in 

class I areas, so a source causing a 0.5 

deciview change can be expected to be 

contributing to noticeable visibility 

impairment. 

In determining whether the maximum 

threshold of 0.5 deciviews or a lower 

threshold is appropriate for purposes of 

BART, we believe that States should 

consider the number of emissions 

sources affecting the class I area and the 

magnitude of the individual sources’

impacts.33 In general, a larger number of 

sources causing impacts in a class I area 

may warrant a lower contribution 

threshold. In selecting a threshold, 

States may want to take into account the 

fact that individual sources have 

varying amounts of impact on visibility 

in class I areas. Depending on the facts 

regarding the number of sources 

affecting a class I area and their 

modeled impacts, the State could set a 

threshold that captures those sources 

responsible for most of the total 

visibility impacts, while still excluding 

other sources with very small impacts.34

We also note that under this guidance, 

States would have discretion in setting 

the threshold for ‘‘contributes to’’ based 

on modeled impacts of sources. 

Consistent with American Corn 

Growers, we are not requiring States to 

find sources subject to BART regardless 

of their impact on Class I areas. We are 

suggesting that, in establishing a 

threshold for assessing contribution for 

BART, it may be logical to draw a line 

between ‘‘contribution’’ and ‘‘noncontribution’’ based on the number and 

magnitude of the various sources 

affecting the Class I areas at issue. Such 

an approach gives States the ability to 

assess the empirical evidence showing 

contribution and to design an 

appropriate regulatory regime in light of 

the nature of the problem. We note that 

for 750 MW power plants, such a line 

drawing exercise is likely to be 

unnecessary, as such sources will in 

most or all cases have impacts far 

exceeding 1.0 deciviews. 

Finally, we disagree that separate 

threshold levels should be established 

based on geography because a unit 

change in visibility expressed in 

deciviews, perceived or measured, is the 

same regardless of geography. As 

explained in the 1999 regional haze 

rule, the deciview can be used to 

express changes in visibility impairment 

in a way that corresponds to human 

perception in a linear manner. As a 

result, using the deciview as the metric 

for measuring visibility means, for 

example, that a one deciview change in 

a highly impaired environment would 

be perceived as roughly the same degree 

of change as one deciview in a relatively 

clear environment, and geography is not 

a factor. 

Interpretation of CALPUFF Results 

The standard CALPUFF modeling run 

provides day-by-day estimates of a 

source’s visibility effects over a five-year 

period. In the proposed BART 

guideline, we indicated that if the 

maximum daily visibility value at any 

receptor over the five years modeled is 

greater than the ‘‘cause or contribute’’

threshold, then the State should 

conclude that the source is subject to 

BART. A number of commenters took 

issue with our proposal to use the 24-

hour maximum modeled visibility 

impact over five years of meteorological 

data. Several of them pointed out, for 

example, that the maximum modeled 

24-hour impact may be an outlier 

unduly influenced by weather. We agree 

that the maximum modeled effect in a 

five-year period could be the result of 

unusual meteorology. We also recognize 

that, although CALPUFF is the best 

currently available tool for analyzing the 

visibility effects of individual sources, it 

is a model that includes certain 

assumptions and uncertainties. Thus, 

we agree with commenters that a State 

should not necessarily rely on the 

maximum modeled impact in 

determining whether a source may 

reasonably be anticipated to contribute 

to visibility impairment in a Class I area. 

The final guideline states that it 

would be reasonable for States to 

compare the 98th percentile of 

CALPUFF modeling results against the 

‘‘contribution’’ threshold established by 

the State for purposes of determining 

BART applicability. Some stakeholders 

have argued for the 90th percentile 

value, or even lower, contending that 

EPA should not use extreme cases to 

make BART applicability decisions. 

EPA agrees that, in most cases, 

important public policy decisions 

should not be based on the extreme tails 

of a distribution. We have concluded, 

however, that the 98th percentile is 

appropriate in this case. 

The use of 90th percentile value 

would effectively allow visibility effects 

that are predicted to occur at the level 

of the threshold (or higher) on 36 or 37 

days a year. We do not believe that such 

an approach would be consistent with 

the language of the statute. Second, we 

note that the 98th percentile value 

would only be used to determine 

whether a particular BART-eligible 

source would be subject to further 

review by the State. In determining 

what, if any, emission controls should 

be required, the State will have the 

opportunity to consider the frequency, 

duration, and intensity of a source’s 

predicted effect on visibility. 

On the other hand, there are other 

features of our recommended modeling 

approach that are likely to overstate the 

actual visibility effects of an individual 

source. Most important, the simplified 

chemistry in the model tends to magnify 

the actual visibility effects of that 

source. Because of these features and 

the uncertainties associated with the 

model, we believe it is appropriate to 

use the 98th percentile—a more robust 

approach that does not give undue 

weight to the extreme tail of the 

distribution. The use of the 98th 

percentile of modeled visibility values 

would appear to exclude roughly 7 days 

per year from consideration. In our 

judgment, this approach will effectively 

capture the sources that contribute to 

visibility impairment in a Class I area, 

while minimizing the likelihood that 

the highest modeled visibility impacts 

might be caused by unusual 

meteorology or conservative 

assumptions in the model. 

39122 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

35H.R. Rep. No. 95–294 at 204 (1077).

36To determine whether a BART-eligible source 

‘‘may reasonably be anticipated to cause or 

contribute to any visibility impairment in any Class 

I area,’’ it may not always be sufficient for the State 

to predict the impacts of a BART-eligible source 

only on the nearest Class I area (or on the nearest 

receptor in the nearest Class I area). The particular 

meteorological and topographical conditions, for 

example, could mean that a source’s greatest 

impacts occurred at a Class I area other than the 

nearest one.

37PLUVUEII is a model used for estimating visual 

range reduction and atmospheric discoloration 

caused by plumes resulting from the emissions of 

particles, nitrogen oxides, and sulfur oxides from a 

single source. The model predicts the transport, 

dispersion, chemical reactions, optical effects and 

surface deposition of point or area source 

emissions. It is available at http://www.epa.gov/

scram001/tt22.htm#pluvue.

38The model code and its documentation are 

available at no cost for download from http://

www.epa.gov/scram001/tt22.htm#calpuff.

Use of CALPUFF for Visibility Modeling 

Background. In providing the States 

with the option of making a 

determination as to which sources are 

subject to BART based on a 

consideration of each source’s 

individual contribution to visibility 

impairment, we proposed that States 

use an air quality model such as 

CALPUFF. We also proposed that States 

use a CALPUFF or other EPA approved 

model in the BART analysis itself. The 

CALPUFF system, as explained in the 

2004 reproposed guideline, consists of a 

diagnostic meteorological model, a 

gaussian puff dispersion model with 

algorithms for chemical transformation 

and complex terrain, and a post 

processor for calculating concentration 

fields and visibility impacts.

The regional haze rule addresses 

visibility impairment caused by 

emissions of fine particles and their 

precursors. As fine particle precursors, 

such as SO2 or NOX, are dispersed, they 

react in the atmosphere with other 

pollutants to form visibility-impairing 

pollutants. In fact, Congress implicitly 

recognized in 1977 the role of chemical 

transformation in creating visibility 

impairment, when it stated that the 

‘‘visibility problem is caused primarily 

by emissions of SO2, [NOX], and 

particulate matter.’’ 35 In most cases, to 

predict the impacts of a source’s specific 

contribution to visibility impairment, a 

State will need a tool that takes into 

account not only the transport and 

diffusion of directly emitted PM2.5 but 

also one that can address chemical 

transformation.

Because the air quality model 

CALPUFF is currently the best 

application available to predict the 

impacts of a single source on visibility 

in a Class I area, we proposed that a 

CALPUFF assessment be used as the 

preferred approach first, for determining 

whether an individual source is subject 

to BART, and second, in the BART 

determination process. The CALPUFF 

assessment is specific to each source, 

taking into account the individual 

source’s emission characteristics, 

location, and the particular 

meteorological, topographical, and 

climatological conditions of the area in 

which the source is located, any of 

which may have an impact on the 

transport of PM2.5 and its precursors. 

CALPUFF can be used to estimate not 

only the effects of directly emitted PM2.5

emissions from a source, but also to 

predict the visibility impacts from the 

transport and chemical transformation 

of fine particle precursors. 

The CALPUFF model is generally 

intended for use on scales from 50 km 

to several hundred kilometers from a 

source. As a general matter, States will 

typically need to assess the impacts of 

potential BART sources on Class I areas 

located more than 50 km from the 

source.36 However, in situations where 

the State is assessing visibility impacts 

for source-receptor distances less than 

50 km, we proposed that States use their 

discretion in determining visibility 

impacts, giving consideration to both 

CALPUFF and other EPA-approved 

methods. As an example, we suggested 

that States could use an appropriate 

local-scale plume impact model, such as 

PLUVUEII,37 to determine whether a 

source’s emissions are below a level that 

would be reasonably anticipated to 

cause or contribute to visibility 

impairment in any Class I area.

Comments. A number of States, 

environmental groups, and some 

industry commenters strongly 

supported the use of CALPUFF as 

proposed. Many commenters supported 

the use of CALPUFF but indicated that 

States must have the flexibility to use 

additional tools for their individual 

source analyses. Some suggested 

options for the ‘‘cause or contribute’’

determination were the use of 

photochemical grid models, or more 

simplified, non-modeling approaches. 

Commenters claimed that States must 

have the option to incorporate advances 

in science and technologies into models 

or other applications that may produce 

more accurate simulations of 

meteorology, chemistry, and visibility 

impairment. Other industry groups and 

States argued that CALPUFF has 

significant limitations, especially 

simulating complex atmospheric 

chemistry, and that EPA’s 

recommendation of CALPUFF as the 

preferred approach is therefore 

inappropriate. 

Another issue raised by commenters 

was the use of CALPUFF for estimating 

secondary particulate matter formation. 

Commenters recognized that CALPUFF 

was incorporated into the ‘‘Guideline on 

Air Quality Models’’ at 40 CFR part 51, 

appendix W in April 2003 as the 

preferred model for Prevention of 

Significant Deterioration (PSD) 

increment and National Ambient Air 

Quality Standards (NAAQS) compliance 

assessments of long range transport of 

primary emissions of SO2 and PM2.5. 

However, commenters stated that 

CALPUFF has not been incorporated 

into the Guideline on Air Quality 

Models for predicting the secondary 

formation of PM. The commenters 

remarked that EPA guidance indicates 

that photochemical grid models be used 

to simulate secondary PM formation and 

concluded on this basis that the 

application of CALPUFF as we 

proposed is in conflict with our 

guidance.

Final rule. We believe that CALPUFF 

is an appropriate application for States 

to use for the particular purposes of this 

rule, to determine if an individual 

source is reasonably anticipated to 

cause or contribute to impairment of 

visibility in Class I areas, and to predict 

the degree of visibility improvement 

which could reasonably be anticipated 

to result from the use of retrofit 

technology at an individual source. We 

encourage States to use it for these 

purposes.38

CALPUFF is the best modeling 

application available for predicting a 

single source’s contribution to visibility 

impairment. It is the only EPA-approved 

model for use in estimating single 

source pollutant concentrations 

resulting from the long range transport 

of primary pollutants. In addition, it can 

also be used for some purposes, such as 

the visibility assessments addressed in 

today’s rule, to account for the chemical 

transformation of SO2 and NOX. As 

explained above, simulating the effect of 

precursor pollutant emissions on PM2.5

concentrations requires air quality 

modeling that not only addresses 

transport and diffusion, but also 

chemical transformations. CALPUFF 

incorporates algorithms for predicting 

both. At a minimum, CALPUFF can be 

used to estimate the relative impacts of 

BART-eligible sources. We are confident 

that CALPUFF distinguishes, 

comparatively, the relative 

contributions from sources such that the 

differences in source configurations, 

sizes, emission rates, and visibility 

impacts are well-reflected in the model 

results. States can make judgements 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39123

39Under CAA section 165(a), a major emitting 

facility may not be constructed unless the owner or 

operator of the facility demonstrates that the 

emissions from the facility will not cause or 

contribute air pollution in excess of an increment 

or NAAQS.

40CALPUFF Analysis in Support of the Regional 

Haze Rule, U.S. Environmental Protection Agency, 

April 15, 2005, Docket No. OAR–2002–0076.

41 Ibid.

concerning the conservativeness or 

overestimation, if any, of the results. In 

fact, although we focused on the use of 

CALPUFF for primary pollutants in 

revising the Guideline of Air Quality 

Modeling, section 7.2.1.e. of the 

Guideline states:

e. CALPUFF (Section A.3) may be applied 

when assessment is needed of reasonably 

attributable haze impairment or atmospheric 

deposition due to one or a small group of 

sources. This situation may involve more 

sources and larger modeling domains than 

that to which VISCREEN ideally may be 

applied. The procedures and analyses should 

be determined in consultation with the 

appropriate reviewing authority (paragraph 

3.0(b) and the affected FLM(s).

We believe that our proposed use of 

CALPUFF is thus fully in keeping with 

the Guideline on Air Quality Models,

especially in light of the low triggering 

threshold for determining whether a 

source is reasonably anticipated to 

cause or contribute to visibility 

impairment in a Class I area, and the 

fact that the modeling results are used 

as only one of five statutory criteria 

evaluated to determine BART emission 

limits. 

Even so, as commenters point out, 

CALPUFF has not yet been fully 

evaluated for secondary pollutant 

formation. For the specific purposes of 

the regional haze rule’s BART 

provisions, however, we have 

concluded that CALPUFF is sufficiently 

reliable to inform the decision making 

process. 

EPA revised the Guideline on Air 

Quality Models in 2003, in part, to add 

CALPUFF to the list of approved models 

for particular uses. At that time, we 

considered comments that CALPUFF 

should be approved for use in 

predicting the impact of secondary 

emissions on particulate matter 

concentrations. As we stated in the 

revision, CALPUFF represents a 

substantial improvement in methods for 

assessing long-range transport of air 

pollutants. However, as explained in the 

response to comments for that 

rulemaking, the modeling results in the 

context of a PSD review may be used as 

the sole determining factor in denying a 

source a permit to construct.39 Although 

its use in simulating long-range 

transport is beneficial, given the 

significance of the modeling results in 

assessing increment consumption due to 

a single source’s impacts, we made a 

determination that it would not be 

appropriate in the rulemaking revising 

Appendix W to approve CALPUFF for 

use in modeling secondary emissions.

In contrast to the significance of the 

modeling results in the PSD context, the 

use of CALPUFF in the context of the 

regional haze rule is not determinative 

of a source’s ability to construct or 

operate. A State may use CALPUFF to 

determine whether a source can 

reasonably be anticipated to cause or 

contribute to visibility impairment and 

so should be subject to additional 

review to determine if the source should 

be subject to control. 

Based on our analysis of the power 

plants covered by the guidelines, we 

believe that all but a handful of these 

plants have impacts of greater than 1.0 

deciview on one or more Class I areas.40

In fact, we anticipate that most of these 

plants are predicted to have much 

higher maximum impacts.41 Because of 

the scale of the predicted impacts from 

these sources, CALPUFF is an 

appropriate or a reasonable application 

to determine whether such a facility can 

reasonably be anticipated to cause or 

contribute to any impairment of 

visibility. In other words, to find that a 

source with a predicted maximum 

impact greater than 2 or 3 deciviews 

meets the contribution threshold 

adopted by the States does not require 

the degree of certainty in the results of 

the model that might be required for 

other regulatory purposes.

In the unlikely case that a State were 

to find that a 750 MW power plant’s 

predicted contribution to visibility 

impairment is within a very narrow 

range between exemption from or being 

subject to BART, the State can work 

with EPA and the FLM to evaluate the 

CALPUFF results in combination with 

information derived from other 

appropriate techniques for estimating 

visibility impacts to inform the BART 

applicability determination. Similarly 

for other types of BART eligible sources, 

States can work with the EPA and FLM 

to determine appropriate methods for 

assessing a single source’s impacts on 

visibility. 

As discussed in section E. below we 

also recommend that the States use 

CALPUFF as a screening application in 

estimating the degree of visibility 

improvement that may reasonably be 

expected from controlling a single 

source in order to inform the BART 

determination. As we noted in 2004, 

this estimate of visibility improvement 

does not by itself dictate the level of 

control a State would impose on a 

source; ‘‘the degree of improvement in 

visibility which may reasonably be 

anticipated to result from the use of 

[BART]’’ is only one of five criteria that 

the State must consider together in 

making a BART determination. The 

State makes a BART determination 

based on the estimates available for each 

criterion, and as the CAA does not 

specify how the State should take these 

factors into account, the States are free 

to determine the weight and 

significance to be assigned to each 

factor. CALPUFF accordingly is an 

appropriate application for use in 

combination with an analysis of the 

other statutory factors, to inform 

decisions related to BART. 

We understand the concerns of 

commenters that the chemistry modules 

of the CALPUFF model are less 

advanced than some of the more recent 

atmospheric chemistry simulations. To 

date, no other modeling applications 

with updated chemistry have been 

approved by EPA to estimate single 

source pollutant concentrations from 

long range transport. In its next review 

of the Guideline on Air Quality Models, 

EPA will evaluate these and other newer 

approaches and determine whether they 

are sufficiently documented, technically 

valid, and reliable to approve for general 

use. In the meantime, as the Guideline 

makes clear, States are free to make their 

own judgements about which of these or 

other alternative approaches are valid 

and appropriate for their intended 

applications. 

Theoretically, the CALPUFF 

chemistry simulations, in total, may 

lead to model predictions that are 

generally overestimated at distances 

downwind of 200 km. Again, States can 

make judgements concerning the 

conservativeness or overestimation, if 

any, of the results. 

The use of other models and 

techniques to estimate if a source causes 

or contributes to visibility impairment 

may be considered by the State, and the 

BART guidelines preserve a State’s 

ability to use other models. Regional 

scale photochemical grid models may 

have merit, but such models have been 

designed to assess cumulative impacts, 

not impacts from individual sources. 

Such models are very resource intensive 

and time consuming relative to 

CALPUFF, but States may consider their 

use for SIP development in the future as 

they are adapted and demonstrated to be 

appropriate for single source 

applications. However, to date, regional 

models have not been evaluated for 

single source applications. Their use 

may be more appropriate in the 

cumulative modeling options discussed 

39124 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

42For regional haze applications, regional scale 

modeling typically involves use of a photochemical 

grid model that is capable of simulating aerosol 

chemistry, transport, and deposition of airborne 

pollutants, including particulate matter and ozone. 

Regional scale air quality models are generally 

applied for geographic scales ranging from a multistate to the continental scale. Because of the design 

and intended applications of grid models, they may 

not be appropriate for BART assessments, so States 

should consult with the appropriate EPA Regional 

Office prior to carrying out any such modeling.

43 Guidance for Estimating Natural Visibility 

Conditions Under the Regional Haze Rule, U.S. 

Environmental Protection Agency, September 2003. 

http://www.epa.gov/ttncaaa1/t1/memoranda/

rh_envcurhr_gd.pdf. Natural background 

conditions, expressed in deciviews, are defined for 

each Class I area. EPA has issued guidance for 

estimating natural background conditions which 

has estimates of default conditions as well as 

measures to develop refined estimates of natural 

conditions.

44See also our explanation of the CAA goal 

provided in the regional haze rule at 64 FR at 

35720–35722. We note that the court in American 

Corn Growers also observed, ‘‘the natural visibility 

goal is not a mandate, it is a goal.’’ 291 F.3d at 27.

above.42 In evaluating visibility 

improvement as one of the five factors 

to consider in setting BART controls, 

other models, used in combination with 

CALPUFF may be helpful in providing 

a relative sense of the source’s visibility 

impact and can aid in informing the 

BART decision. A discussion of the use 

of alternative models is given in the 

Guideline on Air Quality in appendix 

W, section 3.2.

The Use of Natural Conditions in 

Determining Visibility Impacts for 

Reasonable Progress and Comparison to 

Threshold Values 

Background. As set out in section 

169A(a) of the CAA and stated in the 

1999 regional haze rule, a return to 

natural visibility conditions, or the 

visibility conditions that would be 

experienced in the absence of humancaused impairment, is the ultimate goal 

of the regional haze program. To 

measure progress toward this goal, the 

regional haze rule requires that a 

comparison with natural conditions for 

the 20 percent best and worst days to 

calculate ‘‘reasonable progress’’

determinations. Default values for 

natural visibility conditions are 

provided in EPA guidance.43 In the 2004 

reproposal of the BART guidelines, we 

proposed that changes in visibility, 

expressed in deciviews, should be 

determined by comparing the impact 

from a single source to natural visibility 

conditions. That impact should then be 

compared to a threshold impact, also 

expressed in deciviews, to assess if a 

BART-eligible source should be subject 

to a BART review.

Comments. Opposing commenters 

said that a return to natural conditions 

is unattainable as it would require the 

elimination of every manmade source, 

and that changes should be compared 

against currently existing conditions. 

They added that true ‘‘natural 

conditions’’ cannot be verified, do not 

account for manmade emissions from 

other countries, and are not a realistic 

target for improvement. Further, they 

argued that natural conditions are a 

‘‘goal’’ representing a benchmark that is 

relevant to the States’ determination, 

under the regional haze program, of the 

level of ‘‘reasonable progress’’ to 

achieve; however they stated that there 

is no legal requirement (and there could 

not be a legal requirement) that the 

natural conditions goal ultimately must 

be achieved. Several commenters added 

that current visibility conditions make 

more sense as a baseline because 

sources that are subject to BART today 

will likely not be in operation in the 

2064 time frame. A commenter added 

that using current visibility conditions 

for the analysis will give a more 

realistic, real-world prediction of 

whether controlling the source pursuant 

to BART will actually improve 

visibility. The commenter said that 

Congress did not intend for sources to 

have to consider retrofitting controls 

under the BART provision if those 

sources currently are not impacting realworld visibility. Other utility groups 

stated that in addition to international 

emissions, the estimated natural 

visibility conditions failed to account 

for natural phenomena such as sea salt, 

wildfires, and natural organics. One 

commenter noted that natural visibility 

estimates will be revised and refined 

over time and it would be unwise to 

compare impacts and improvements to 

a moving baseline.

On the other hand, numerous 

commenters supported the use of 

natural visibility conditions as a 

baseline for measuring visibility 

improvements. Several environmental 

groups said that any increase in the 

baseline beyond natural visibility 

conditions will unlawfully distort and 

weaken the BART requirement by 

effectively raising the applicability 

threshold in less protected, highly 

polluted areas, which would be 

illogical. Further, they pointed out that 

these BART-eligible sources clearly are 

contributing to the very manmade 

visibility impairment that the Act is 

explicitly designed to remedy by a 

return to natural conditions. They 

added that measuring natural conditions 

as opposed to some other baseline 

condition is a more appropriate 

approach, given that the planning goal 

is to achieve natural visibility by the 

end of the program. They also added 

that a baseline other than natural 

conditions would never assure 

‘‘reasonable progress’’. 

Finally, two commenters asked for 

clarification on the values for natural 

conditions to be used for estimating 

changes in visibility. The commenters 

appeared to assume that we intended for 

the comparison to be done for natural 

visibility conditions on the 20 percent 

best days. 

Final Rule. We disagree with 

commenters saying that the use of 

natural conditions as the baseline for 

making visibility impact determinations 

is inappropriate. The visibility goal of 

the CAA is both the remedying of 

existing impairment, and prevention of 

future impairment. The court, in 

American Corn Growers, upheld our 

interpretation of that goal as the return 

to natural visibility conditions.44 Longterm regional haze strategies are 

developed to make ‘‘reasonable 

progress’’ towards the CAA goal, and 

States must demonstrate reasonable 

progress in their regional haze State 

implementation plans (SIPs). Since the 

BART program is one component of that 

demonstration, visibility changes due to 

BART are appropriately measured 

against the target of natural conditions.

In establishing the goal of natural 

conditions, Congress made BART 

applicable to sources which ‘‘may be 

reasonably anticipated to cause or 

contribute to any impairment of 

visibility at any Class I area’’. Using 

existing conditions as the baseline for 

single source visibility impact 

determinations would create the 

following paradox: the dirtier the 

existing air, the less likely it would be 

that any control is required. This is true 

because of the nonlinear nature of 

visibility impairment. In other words, as 

a Class I area becomes more polluted, 

any individual source’s contribution to 

changes in impairment becomes 

geometrically less. Therefore the more 

polluted the Class I area would become, 

the less control would seem to be 

needed from an individual source. We 

agree that this kind of calculation would 

essentially raise the ‘‘cause or 

contribute’’ applicability threshold to a 

level that would never allow enough 

emission control to significantly 

improve visibility. Such a reading 

would render the visibility provisions 

meaningless, as EPA and the States 

would be prevented from assuring 

‘‘reasonable progress’’ and fulfilling the 

statutorily-defined goals of the visibility 

program. Conversely, measuring 

improvement against clean conditions 

would ensure reasonable progress 

toward those clean conditions. 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39125

45 Guidance for Estimating Natural Visibility 

Conditions Under the Regional Haze Rule, U.S. 

Environmental Protection Agency, September 2003. 

http://www.epa.gov/ttncaaa1/t1/memoranda/

rh_envcurhr_gd.pdf.

46 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.

With regard to BART-eligible sources 

not being in operation for the duration 

of the program, a State, in making BART 

determinations, is explicitly directed by 

the CAA to account for the remaining 

useful life of a source. Thus, States may 

factor into their reasonable progress 

estimates those shut-downs that are 

required and effected in permit or SIP 

provisions. In addition, as provided for 

under our guidance,45 proper 

accounting for international emissions 

and natural phenomena is in the 5 year 

SIP progress report, not in the setting of 

natural visibility estimates. Finally, 

these final BART guidelines use the 

natural visibility baseline for the 20 

percent best visibility days for 

comparison to the ‘‘cause or contribute’’

applicability thresholds. We believe this 

estimated baseline is likely to be 

reasonably conservative and consistent 

with the goal of natural conditions.

Modeling Protocol 

Background. The 2004 guidelines 

proposed that a written modeling 

protocol be submitted for assessing 

visibility impacts from sources at 

distances greater than 200 km from a 

Class I area. The proposal indicated that 

the protocol should include a 

description of the methods and 

procedures to follow, for approval by 

the appropriate reviewing authority; 

critical items to include in the protocol 

are meteorological and terrain data, 

source-specific information (stack 

height, temperature, exit velocity, 

elevation, and allowable emission rate 

of applicable pollutants), and receptor 

data from appropriate Class I areas. 

Comments. All of the comments 

supported the development of a written 

modeling protocol. Industry, Federal, 

and State commenters said a modeling 

protocol should be required of all States 

and stakeholders who are performing 

the BART modeling analysis. 

Commenters said the protocol should 

allow all interested parties an 

opportunity to understand the modeling 

approach and how the results will be 

used, and that the State should provide 

opportunity for comments on the 

procedures prior to the publication of 

the final results. 

Many utility groups commented that 

the protocol should provide States with 

flexibility and that the choice of models 

should be at the States’ (or RPOs’) 

discretion. Some commenters stressed 

that it is important that states and 

sources retain the flexibility to decide 

how to set up and run the selected 

model, while others asked for specific 

guidance on the setup of CALPUFF or 

other approved models, including on 

specific parameters (e.g. how to adjust 

for cases where sources are greater than 

200 km from a Class I area). 

Regarding the approval of a modeling 

protocol, some commenters said that the 

protocol should be approved by EPA. 

Others stated, however, that we should 

have only an advisory role in 

development of the protocol. They said 

that States are in a better position to 

determine which modeling input values 

best reflect conditions in their States. 

Several commenters representing 

environmental groups said we should 

develop a CALPUFF protocol that must 

be followed and should include, among 

other items, meteorological data (i.e., 

where available 5 years of data should 

be used), emissions reported for the 

same meteorological years, documented 

source parameters, model physical 

parameters, and assumed background 

concentrations for ozone and ammonia 

(based on nearby reliable observations 

and/or regional modeling results). They 

added that a protocol developed by EPA 

would help to produce consistent BART 

determinations across various sources 

and geographic areas for both shorter 

and longer distances. FLMs stated that 

this is also an appropriate time to create 

regional modeling platforms for 

CALPUFF, which would allow States 

and sources to run the model more 

expeditiously and more consistently. 

They recommended that we consider a 

multi-agency process to reach agreement 

on an appropriate modeling protocol 

prior to allowing BART applicability 

and control determinations to be based 

on model results. FLMs added that it 

would be helpful to establish a national 

procedure for this process, including a 

methodology for establishing natural 

background conditions, background 

ammonia concentrations, and 

determining sulfuric acid emission 

rates. Such a process, they said, could 

reasonably be engaged in prior to 

deadlines for state implementation 

plans, and would not delay 

implementation of the BART guidelines. 

The FLMs noted that consistent, 

nationally applicable guidance is 

essential, and that once it is developed, 

virtually no deviations should be 

allowed. Finally, they added that the 

CALPUFF modeling exercises should 

follow the Interagency Workgroup on 

Air Quality Modeling (IWAQM) Phase 2 

Summary Report and Recommendations 

for Modeling Long Range Transport 

Impacts,46 but that we, in consultation 

with the FLMs and States, should also 

publish additional guidance to address 

more recent issues such as particle 

speciation, emission rate averaging 

times, and ‘‘natural obscuration.’’

Another State commenter said that The 

Guideline on Air Quality Models (CFR 

Part 51, Appendix W) should be 

included along with the IWAQM Report 

as a reference for CALPUFF setup. One 

RPO commented that we should provide 

data, perhaps using example facilities, 

to demonstrate the effect of the process 

so that States can get a better feeling for 

which sources are likely to fall below 

the 0.5 deciview threshold. This would 

help States understand the net effect of 

all of the parameters chosen in the 

exemption process.

Commenters also said that we should 

continuously revise modeling protocols 

by providing a modeling clearinghouse 

to States, and further, that we should 

consider new models for use, such as 

the Community Multiscale Air Quality 

(CMAQ) model. 

There were specific comments 

requesting guidance for calculating 

visibility impacts and other general 

modeling concerns. One technical 

comment was that the guidelines should 

specify that the IMPROVE monitor is 

the receptor by which modeled 

visibility impacts should be evaluated 

with the CALPUFF model. Another 

commenter suggested using recent 

scientific evidence to update the light 

extinction coefficients used by 

CALPUFF to calculate visibility 

changes. These commenters also stated 

that CALPUFF might be improved by 

capping the relative humidity to lower 

values than are currently used. 

Additional commenters representing 

utility organizations discussed how to 

identify Class I areas that should be 

modeled. They said that the guidelines 

should require sources to model only 

the nearest Class I area (or possibly the 

two closest), and one commenter said 

that we should provide a reasonable 

methodology to minimize the effort 

needed to address impacts from BARTeligible sources on multiple Class I 

areas.

Final Rule. We agree that States 

should adopt modeling protocols for all 

modeling demonstrations, regardless of 

the distance from the BART-eligible 

source and the Class I area impacted. 

We are therefore dropping the 200 km 

and greater distance requirement from 

the guidelines. As noted in the 2004 reVerDate jul<14>2003 19:24 Jul 05, 2005 Jkt 205001 PO 00000 Frm 00023 Fmt 4701 Sfmt 4700 E:\FR\FM\06JYR3.SGM 06JYR3
39126 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

47http://www.src.com/calpuff/calpuff1.htm.

48CALPUFF 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.

49Analysis of the CALMET/CALPUFF Modeling 

System in a Screening Mode, U.S. Environmental 

Protection Agency, November 1998, Docket No. 

OAR–2002–0076.

proposal, we believe that potential 

uncertainties in model performance may 

be greater at distances greater than 200 

km for a source. A modeling protocol 

may reduce the need for additional 

analyses. We favor coordination among 

States, EPA regions, RPOs, and other 

federal agencies to agree on a modeling 

protocol(s) which would provide 

consistent application. 

In developing a modeling protocol, 

we also encourage States to use the 

framework provided for model setup in 

EPA’s IWAQM. CALPUFF model users 

may find default settings in that 

document which may be appropriate for 

their modeling situations and add an 

element of consistency to model 

applications. The Guideline on Air 

Quality Models (CFR Part 51, Appendix 

W) also provides useful guidance. 

We do, however, understand and 

agree that States have flexibility 

developing a modeling protocol. 

Moreover, the diversity of the nation’s 

topography and climate, and variations 

in source configurations and operating 

characteristics, dictate against a strict 

modeling ‘‘cookbook’’. A State may 

need to address site-specific 

circumstances at individual sources 

potentially affecting a specific Class I 

area. For example, in a particular area 

a State may have available emissions 

data, that is more representative of the 

modeling domain, which may 

supplement the model defaults. States 

may want to consult with the 

appropriate EPA regional office and 

Federal Land Managers in adjusting the 

model input parameters. The modeling 

input recommendations in the IWAQM 

report are designed for visibility impact 

applications, and those defaults allow 

for tailoring for a given application (e.g.

puff splitting). The model developers 

Web site 47 also has a series of 

frequently asked questions with answers 

to assist users in tailoring model 

applications.

We agree that we have only an 

advisory role in development of the 

protocol as the States better understand 

the BART-eligible source configurations 

and the geophysical and meteorological 

data affecting their particular Class I 

area(s). 

In the protocol development process, 

we support the idea of designing 

example runs, as we have done in our 

example analysis for EGUs,48 so that 

States may get a better understanding of 

what visibility impacts might be 

expected from a particular type of 

source or sources. Once a protocol has 

been finalized, a State may be able to 

use example runs as a proxy in making 

BART determinations which could 

potentially eliminate the need for caseby-case review for every BART-eligible 

source. A common sense approach 

should be taken, particularly where an 

analysis may add a significant resource 

burden to a State. For example, if there 

are multiple Class I areas in relatively 

close proximity to a BART-eligible 

source, a State may model a full field of 

receptors at the closest Class I area. 

Then a few strategic receptors may be 

added at the other Class I areas (perhaps 

at the closest point to the source, a 

receptor at the highest and lowest 

elevation in the Class I area, a receptor 

at the IMPROVE monitor, and a few 

receptors that are expected to be at the 

approximate plume release height). If 

the highest modeled impacts are 

observed at the nearest Class I area, a 

State may choose not to analyze the 

other Class I areas any further and 

additional analyses might be 

unwarranted.

As models are revised and advances 

in science are incorporated into the 

models, we can make certain that 

revisions to protocols are made 

accordingly. We will work closely with 

States and FLMs, as should States; we 

expect that States will also work closely 

with FLMs throughout the protocol 

development process. We expect a 

similar protocol development process 

for other models that may be used, once 

those models are developed to predict 

and track single source impacts and 

demonstrate acceptable model 

performance. States should contact the 

appropriate FLM and EPA regional 

office for the latest guidance and 

modeling updates. 

Alternatives for Determining Visibility 

Impacts From Individual Sources 

Background. In the 2004 reproposal, 

we requested comment on the following 

alternatives to CALPUFF modeling for 

determining whether individual sources 

cause or contribute to visibility 

impairment: look-up tables developed 

from screening-level air quality 

modeling; running CALPUFF in a 

simpler screening mode than the 

preferred approach; a source ranking 

methodology; and an emissions divided 

by distance (Q/D) method. Except for 

the simplified CALPUFF approach, all 

alternatives were based on developing a 

relationship between source emissions 

and the source’s distance to a Class I 

area. Each of these approaches was 

intended to reduce the resource burden 

on States. 

Comments. Some commenters 

supported the use of alternative 

approaches, while others suggested that 

the alternatives could be used either in 

conjunction, or in hierarchical fashion, 

with modeling approaches. Many 

commenters were opposed to their use. 

The opposing comments were 

consistent in stating that the alternatives 

were inappropriate because they did not 

account for important factors such as 

terrain, local meteorological data, 

prevailing wind directions (which 

influence pollutant transport), and 

differences in stack release parameters. 

Commenters added that there is no 

direct connection between emissions, 

distance, and visibility impairment, and 

that the methods treat SO2 and NOX

equally for impairment estimates.

Final Rule. We disagree that the 

alternatives are necessarily 

inappropriate, but we share most of the 

concerns articulated by the opposing 

commenters. We believe that 

alternatives should not be used to 

exempt a source from BART review 

without more rigorous evaluations and 

sensitivity tests showing that the results 

are at least as conservative as the 

CALPUFF model. We know of at least 

one study showing that, for one location 

and for one year, there is no guarantee 

that the simplified CALPUFF technique 

is as conservative as the preferred 

approach 49. While we are not adopting 

in the guideline any specific alternative 

to modeling for power plants greater 

than 750MW, a State may develop its 

own alternative approach for the other 

source categories to determine if a 

source would be subject to BART, 

provided that the alternative 

demonstrates a sufficient basis to 

determine clearly that the source causes 

or contributes to visibility impairment, 

or that more refined analysis is 

warranted. Use of an alternative 

approach could be a conservative nonmodeling method for easing a State’s 

resource burden. We believe 

conservatism is needed because of the 

purpose of the test: i.e. solely to 

determine if a closer look at the source 

is warranted.

E. The BART Determination Process 

Background. CAA section 169A(g)(7) 

directs States to consider five factors in 

making BART determinations. The 

regional haze rule codified these factors 

in 40 CFR 51.308(e)(1)(ii)(B), which 

directs States to identify the ‘‘best 

system of continuous emissions control 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39127

technology’’ taking into account ‘‘the 

technology available, the costs of 

compliance, the energy and nonair 

quality environmental impacts of 

compliance, any pollution control 

equipment in use at the source, and the 

remaining useful life of the source.’’

Section IV. of the BART guidelines 

provides a step-by-step guide to 

conducting a BART determination 

which takes these factors into account. 

This section of the preamble 

addresses a number of issues relative to 

the process for conducting a BART 

determination contained in Section IV 

of the BART guidelines. 

1. What Is Meant by ‘‘Technical 

Feasibility of the Control Options’’ in 

Step 2 of the BART Determination? 

Comments. We received several 

comments on this discussion, both on 

the 2001 proposal and on the 2004 

reproposal. One commenter 

recommended that the concept of 

available technology for regional haze 

should be expanded to include those in 

the pilot scale testing phase, because 

these guidelines will precede the 

installation of controls by about 10 

years. Other commenters believed that 

the discussion of technical feasibility 

introduced terms and concepts that 

were not clear, for example, what is 

meant by ‘‘commercial demonstration.’’

One commenter raised issues with 

deeming technologies used in foreign 

countries ‘‘available’’ unless their 

performance has been demonstrated in 

the United States. A few commenters 

expressed concern with the provision in 

the guidelines that new technologies 

should be considered up to the time of 

a State’s public comment period on the 

BART determination. The commenter 

believed that this could create an 

endless review loop for States if new 

technologies continually became 

available. 

Final rule. In the final guidelines, we 

have largely retained the language that 

was in the proposed guidelines. Because 

the guidelines call for consideration of 

technologies that become available by 

the time of the State’s public comment 

process on the BART determination, 

technologies should be considered that 

become available well after we finalize 

the BART guidelines. We also note, for 

clarity, that the Guidelines state that 

technologies need to be both licensed 

and commercially available (i.e.

commercially demonstrated and sold). 

2. How Should the Costs of Control Be 

Estimated in Step 4 of the BART 

Determination? 

Comments. This section of the 

guidelines remained unchanged 

between the 2001 proposal and the 2004 

reproposal. Comments varied, ranging 

from questioning the reliance on EPA’s 

OAQPS Control Cost Manual Fifth 

Edition, February 1996, EPA 453/B–96–

001 (hereafter called the ‘‘Control Cost 

Manual’’) to requesting that we not 

include the concept of incremental cost 

effectiveness in the guidelines. A 

commenter expressed concerns that 

incremental cost effectiveness 

calculations, the cost of implementing 

each succeeding control option, is too 

dependent on the number of interim 

options included in the analysis. 

Moreover, the commenter believed that 

incremental cost calculations increase 

the complexity of the analysis, and they 

also increase the possibility for 

inconsistent cost results. 

Final rule. We have finalized this 

section of the guidelines with some 

changes to how it was proposed. States 

have flexibility in how they caculate 

costs. We believe that the Control Cost 

Manual provides a good reference tool 

for cost calculations, but if there are 

elements or sources that are not 

addressed by the Control Cost Manual 

or there are additional cost methods that 

could be used, we believe that these 

could serve as useful supplemental 

information. 

In addition, the guidelines continue to 

include both average and incremental 

costs. We continue to believe that both 

average and incremental costs provide 

information useful for making control 

determinations. However, we believe 

that these techniques should not be 

misused. For example, a source may be 

faced with a choice between two 

available control devices, 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.

Finally, it is important to note that, 

while BART determinations are focused 

at individual sources, it is likely that in 

response to SIP requirements, States 

will be making BART determinations for 

many units in a subject source category 

all at the same time. In doing so, States 

are likely to compare costs across each 

source category as well as looking at 

costs for individual units in order to 

respond to SIP requirements in an 

efficient manner (from the State’s 

perspective). 

3. How Should ‘‘Remaining Useful Life’’

Be Considered in Step 4 of the BART 

Determination? 

Comments. We received a number of 

comments on the issue of remaining 

useful life, both on the 2001 proposal 

and on the 2004 reproposal. One 

commenter asserted that remaining 

useful life should not be considered in 

the cost analysis and that if a source is 

in operation at the time of a State’s SIP 

submittal, it must have plans to install 

controls. Other commenters believed 

that, to the extent that assertions 

regarding a plant’s remaining useful life 

influences the BART decision, there 

must be an enforceable requirement for 

the plant to shut down by that date. 

Other comments questioned whether 

Congress intended enforceable 

restrictions in order to take into account 

the remaining useful life and whether 

EPA had the authority under the CAA 

to require plant shutdowns. 

A number of comments were received 

regarding our request for comments on 

how to provide flexibility for situations 

where market conditions change. Some 

comments interpreted this provision as 

a loophole that would allow sources to 

continue operation for a number of 

years without BART. Another comment 

supported the concept of allowing a 

source to later change its mind, so long 

as BART is installed. 

Final rule. We have retained the 

approach in the proposed guidelines, 

including the provision for flexibility 

for sources to continue operating, with 

BART in place, should conditions 

change. We believe that the CAA 

mandates consideration of the 

remaining useful life as a separate 

factor, and that it is appropriate to 

consider in the analysis the effects of 

remaining useful life on costs. We 

believe that, because the source would 

not be allowed to operate after the 5-

year point without such controls, the 

option for providing flexibility would 

not create a loophole for sources. 

Moreover, any source operating after 

this point without BART controls in 

place would be subject to enforcement 

actions for violating the BART limit. For 

any source that does not agree to shut 

down before the 5-year point, the State 

should identify a specific BART 

emission limit that would apply after 

this point in time. 

4. How Should ‘‘Visibility Impacts’’ Be 

Considered in Step 5 of the BART 

Determination? 

Background. The fifth statutory factor 

addresses the degree of improvement in 

39128 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

visibility which may reasonably be 

anticipated to result from the use of the 

‘‘best control technology’’ for sources 

subject to BART. The 2004 reproposal 

focuses on the use of single source 

emissions modeling to evaluate the 

BART control options. As part of the 

BART determination, we proposed that 

a State or individual source would run 

CALPUFF, or another EPA-approved 

model, to estimate, in deciviews, a 

BART source’s visibility impact at a 

Class I area. The source would run the 

model once using its allowable emission 

rates, and then again at the various postcontrol emissions rates being evaluated 

for the BART determination. The 24-

hour model results would then be 

tabulated for the pre- and post-control 

scenarios, for the average of the 20 

percent worst modeled days at each 

receptor, over the time period of 

meteorology modeled. The difference in 

the averages for each receptor is the 

expected degree of improvement in 

visibility. Alternatively, the proposal 

requested comment on the option of 

using the hourly modeled impacts from 

CALPUFF at each receptor and 

determining the improvement in 

visibility based on the number of hours 

above the 0.5 deciview threshold for 

both the pre- and post-control model 

runs. We also requested comment on 

combinations of the proposed and 

alternative options and on the use of the 

simpler screening version of CALPUFF 

to do the analysis. 

Comments. Several environmental 

groups said that issues relating to the 

determination of visibility improvement 

for evaluating BART controls are in 

many ways the same as for determining 

which BART-eligible sources are subject 

to BART. Thus, the commenter pointed 

out, the issues concerning the BART 

applicability test, discussed in section 

D., are all equally applicable here, 

including comments on: using the 0.5 

deciview threshold on an aggregate 

basis for determining visibility 

impairment and potential exemption for 

BART-eligible sources, use of a natural 

visibility baseline versus current 

visibility, using a substantially lower 

deciview threshold than 0.5 deciviews 

to determine the contribution to 

visibility impairment by an individual 

source, and demonstration of those 

thresholds by means of appropriate 

modeling rather than other less reliable 

and more subjective techniques. 

An industry commenter claimed that 

the American Corn Growers case 

emphasized the fact that the CAA 

clearly provides that BART 

determinations should balance the 

visibility benefits of controls 

comprehensively against their burdens; 

the commenter noted that this is not 

mentioned in our proposal; the 

commenter said that although the 

proposal would allow States to run the 

CALPUFF model, it fails to specify how 

they might consider the results.

One State commenter opposed the use 

of visibility modeling for the purpose of 

informing the choice of control option, 

stating that it is unnecessary, confusing 

and without adequate standards or 

guidance for implementation. The State 

added that the analysis of control 

options in the BART process should 

yield the greatest, most cost-effective 

control efficiency for NOX and SO2 at or 

above our presumptive levels of control. 

Moreover, it said that analysis of the 

degree of visibility improvement may 

result in very small increments of 

visibility improvements within Class I 

areas from an individual source, thus 

tilting the selection to the lower control 

efficiency option. The State added that 

we should remove this criterion from 

the analysis to ensure that the best cost 

effective controls will result. Another 

State agency said that modeling impacts 

should not be considered in BART 

determinations because they are not 

considered when determining BACT for 

the PSD program. 

A variety of commenters pointed out 

several areas where the guidelines 

should be improved or clarified in 

regard to the degree of visibility 

improvement determination: 

• We should clarify that the analysis 

is pollutant-specific (e.g., the modeling 

evaluation of a BART control option for 

SO2 reduction should not be combined 

with the modeling evaluation of a BART 

control option for NOX.) 

• We should clarify that only the 

closest Class I area must be modeled. 

• We should describe CALPUFF as 

one possible model to use, rather than 

as the only model that may be used. 

• States and sources should have the 

flexibility to perform multiple modeling 

runs based on different levels of 

available control. 

• Predicted visibility improvements 

that are imperceptible should be given 

no weight in determining the level of 

control that constitutes BART. 

• States should be allowed to 

establish a factor for the required degree 

of visibility improvement. 

Several industry and utility 

commenters expressed concern about 

using allowable emission rates to 

predict visibility impacts for BART 

control options; they argued that actual 

emission rates should be considered 

instead. Three commenters stated that 

we must make clear that States should 

use emission rates that will be 

permissible at the time BART controls 

take effect, not current emissions rates. 

Additional comments from utilities, 

industry, and one State opposed the 

approach wherein the results from the 

20 percent worst modeled days (preand post-control) were used to evaluate 

the visibility improvements expected 

from the various control options. Some 

believed this was too stringent, while 

others said it was not stringent enough. 

Two utilities added that the criteria 

should use the 20 percent worst days 

based on monitored data, not modeled 

data. An environmental group stated 

that sources should not be limited to 

just the worst days, but the 

improvements should be based upon 

controls reducing visibility impairment 

on any day. The commenter added that 

this rationale ignores the middle 60 

percent of days in which visibility may 

worsen, because sources may increase 

emissions on these days as a trade-off 

for cutting emissions on the worst days. 

The commenter further argued that 

there are no data to support our 

assertion that improvement on the worst 

days means improvement on other days. 

They noted that default ‘‘natural 

condition’’ deciview values for Class I 

areas in our natural conditions guidance 

exist only for the average of the 20 

percent best and worst days. The 

commenter added that we used the 

average default natural conditions (for 

the 20 percent best days) for the 

visibility impairment analysis, but there 

are no default ‘‘maximum 24-hour’’

values in the guidance. 

Nine commenters supported 

implementation of visibility 

improvement thresholds, which were 

not proposed in 2004. A State 

commenter said it is unclear how the 

modeled net visibility improvement 

would be specifically utilized in the 

BART analysis, and requested a target 

level of improvement or a de minimis 

level by which to measure 

improvement. Two industry 

commenters suggested alternatives to 

the 24-hour value. One said that setting 

a threshold for comparison, as in the 

BART-applicability test, is more 

appropriate than the overall comparison 

of the 20 percent worst case days, and 

that the threshold for comparison 

should be on at least a daily average (or 

longer), not an hourly average, due to 

the possibility of short-term spikes 

based on certain meteorological 

conditions. 

These commenters also said that a 

comparison of the number of days above 

or below a certain threshold is 

preferable since below a certain 

threshold, the impacts of visibility are 

not perceptible; unlike concentration 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39129

50Pitchford, M. and Malm, W., ‘‘Development 

and Applications of a Standard Visual Index,’’

Atmospheric Environment, V. 28, no. 5, March 

1994.

51Henry, R.C. ‘‘Just-Noticeable Differences in 

Atmospheric Haze’’, Journal of the Air & Waste 

Management Association, 52:1238–1243, October 

2002.

levels of certain pollutants (i.e., ozone) 

which do not have a threshold below 

which there are no effects, there are 

concentration levels of particulate 

below which there is no visibility 

impact. They also asserted that 

comparing the number of days would 

allow for a more complete picture of 

how controls would potentially improve 

visibility. As noted previously, a small 

number of unusual meteorological 

conditions can produce significant 

spikes on a single day or days. Since the 

overall goal of the regional haze rule is 

long-term visibility improvement, they 

said that a comparison of the total 

number of days exceeding a threshold 

over multiple years will provide a better 

overall indicator of visibility 

improvement. One commenter 

suggested that if we retain the maximum 

24-hour value for the visibility 

impairment analysis, we should at least 

allow the use of only 1 year, rather than 

5 years, of meteorological data. That 

would simplify the modeling and would 

lessen the chance that one day with 

atypical, extreme conditions would 

dictate the result.

One FLM supported our proposed 

method to determine visibility 

improvement associated with 

installation of BART. However, with 

regard to the use of hourly data instead 

of 24 hour data for the degree of 

visibility improvement assessment, 

another FLM said that while hourly 

model data are, by their nature, less 

reliable in predicting actual conditions, 

a measure that reports the total number 

of hours above a given threshold would 

still be a useful measure of the longterm effect of BART control. They said 

we should require States to report a 

combination of measures of the 

visibility improvement expected from 

BART. Such measures would be the 

change in the 20 percent worst days as 

well as a metric that examines the 

amount of time during a year that the 

source’s visibility impact would exceed 

a threshold with and without BART. 

Another utility commenter added 

that, if a BART control option would 

result in no perceptible improvement in 

visibility at a Class I area, then it is not 

a cost-effective option. This commenter 

said that based on Pitchford and Malm 

(1994) 50 and Henry (2002) 51 a 2 

deciview threshold of perception would 

be appropriate, with a 1 deciview 

threshold providing a margin of safety. 

Another commenter said that we should 

clarify that visibility improvement 

differences among BART control 

options should be considered 

insignificant if the differences are less 

than the perceptibility threshold level, 

which should be set in excess of 1 

deciview. Other commenters said the 

minimum threshold should be 1 

deciview.

Final Rule. We disagree with the 

comment that modeling should not be 

part of a BART review because it is not 

considered for BACT. CAA section 

169A(g)(2) clearly requires an 

evaluation of the expected degree of 

improvement in visibility from BART 

controls. All five statutory factors, 

including cost-effectiveness and 

expected visibility improvement, should 

be reflected in the level of BART control 

that the State implements. We believe 

that modeling, which provides model 

concentration estimates that are readily 

converted to deciviews, is the most 

efficient way to determine expected 

visibility improvement. 

For the purposes of determining 

visibility improvement, States may 

evaluate visibility changes on a 

pollutant-specific basis. If expected 

improvement is shown from the various 

control choices, the State can weigh the 

results with the other four BART 

determination factors when establishing 

BART for a particular source. For 

example, a State can use the CALPUFF 

model to predict visibility impacts from 

an EGU in examining the option to 

control NOX and SO2 with SCR 

technology and a scrubber, respectively. 

A comparison of visibility impacts 

might then be made with a modeling 

scenario whereby NOX is controlled by 

combustion controls. If expected 

visibility improvements are significantly 

different under one control scenario 

than under another, then a State may 

use that information, along with 

information on the other BART factors, 

to inform its BART determination. 

Even though the visibility 

improvement from an individual source 

may not be perceptible, it should still be 

considered in setting BART because the 

contribution to haze may be significant 

relative to other source contributions in 

the Class I area. Thus, we disagree that 

the degree of improvement should be 

contingent upon perceptibility. Failing 

to consider less-than-perceptible 

contributions to visibility impairment 

would ignore the CAA’s intent to have 

BART requirements apply to sources 

that contribute to, as well as cause, such 

impairment. 

Although we are not requiring States 

to use allowable emission rates to 

predict the anticipated future visibility 

impacts of BART controls, we disagree 

that daily average actual emission rates 

should be used to make this assessment. 

Emissions from a source can vary 

widely on a day to day basis; during 

peak operating days, the 24-hour actual 

emission rate could be more than 

double the daily average. On the other 

hand, in the long term, estimating 

visibility impacts based on allowable 

emission rates for every hour of the year 

may unduly inflate the maximum 24 

hour modeled impairment estimate from 

a BART-eligible source. 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. Where States 

have information on a source’s daily 

emissions, an emission rate based on the 

maximum actual emissions over a 24 

hour period for the most recent five 

years may be a more appropriate gauge 

of a source’s potential impact as it 

would ensure that peak emission 

conditions are reflected, but would 

likely not overestimate a source’s 

potential impact on any given day. We 

have accordingly included this change 

to the final guidelines. We recommend 

that the State use the highest 24-hour 

average actual emission rate, for the 

most recent three or five year period of 

meteorological data, to characterize the 

maximum potential benefit. 

Because each Class I area is unique, 

we believe States should have flexibility 

to assess visibility improvements due to 

BART controls by one or more methods, 

or by a combination of methods, and we 

agree with the commenters suggestions 

to do so. We believe the maximum 24-

hour modeled impact can be an 

appropriate measure in determining the 

degree of visibility improvement 

expected from BART reductions (or for 

BART applicability). We have pointed 

out, however, that States should have 

flexibility when evaluating the fifth 

statutory factor. A State is encouraged to 

account for the magnitude, frequency, 

and duration of the contributions to 

visibility impairment caused by the 

source based on the natural variability 

of meteorology. These are important 

elements to consider as they would 

provide useful information on both the 

short term peak impact and long term 

average assessments which are critical 

in making the visibility assessment.

We agree with the suggestion that the 

use of a comparison threshold, as is 

39130 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

52CALPUFF 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. 53 Ibid.

done for determining if BART-eligible 

sources should be subject to a BART 

determination, is an appropriate way to 

evaluate visibility improvement. 

However, we believe the States 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 States are free to 

determine the weight and significance 

to be assigned to each factor. For 

example, a 0.3, 0.5, or even 1.0 deciview 

improvement may merit stronger 

weighting in one case versus another, so 

one ‘‘bright line’’ may not be 

appropriate. 

In addition, 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, a 

threshold representing an x percent 

change in improvement, etc.). In our 

example modeling analysis of a 

hypothetical source,52 we used three 

different 24-hour thresholds (1.0, 0.5, 

and 0.1 deciviews) and examined the 

number of days that those thresholds 

were exceeded for a source with a 90 

percent change, for example, in SO2

emissions (i.e. 10,000 TPY and 1,000 

TPY). The number of days that the 

thresholds were exceeded in the 10,000 

TPY case was substantial, and the 

visibility improvement due to the 

reduction in emissions was dramatic 

(i.e. the number of days exceeding the 

thresholds dropped considerably).53

Other ways that visibility 

improvement may be assessed to inform 

the control decisions would be to 

examine distributions of the daily 

impacts, determine if the time of year is 

important (e.g. high impacts are 

occurring during tourist season), 

consideration of the cost-effectiveness of 

visibility improvements (i.e. the cost per 

change in deciview), using the measures 

of deciview improvement identified by 

the State, or simply compare the worst 

case days for the pre- and post-control 

runs. States may develop other methods 

as well. 

5. In What Sequence Should 

Alternatives Be Assessed in Step 5 of 

the BART Determination? 

Background. Both the 2001 proposal 

and the 2004 reproposal requested 

comments on two options for evaluating 

the ranked options. Under the first 

option, States would use a sequential 

process for conducting the impacts 

analysis, beginning with a complete 

evaluation of the most stringent control 

option. If a State determines that the 

most stringent alternative in the ranking 

does not impose unreasonable costs of 

compliance, taking into account both 

average and incremental costs, the 

analysis begins with a presumption that 

this level is selected. Under this option, 

States would then proceed to consider 

whether energy and non-air quality 

environmental impacts would justify 

selection of an alternative control 

option. If there are no outstanding 

issues regarding energy and non-air 

quality environmental impacts, the 

analysis is ended and the most stringent 

alternative is identified as the ‘‘best 

system of continuous emission 

reduction.’’ If a State determines that 

the most stringent alternative is 

unacceptable due to such impacts, this 

approach would require them to 

document the rationale for this finding 

for the public record. Then, the next 

most-effective alternative in the listing 

becomes the new control candidate and 

is similarly evaluated. This process 

would continue until the State identifies 

a technology which does not pose 

unacceptable costs of compliance, 

energy and/or non-air quality 

environmental impacts. 

We also requested comment on an 

alternative decision-making approach 

that would not begin with an evaluation 

of the most stringent control option. For 

example, States could choose to begin 

the BART determination process by 

evaluating the least stringent technically 

feasible control option or by evaluating 

an intermediate control option drawn 

from the range of technically feasible 

control alternatives. Under this 

approach, States would then consider 

the additional emissions reductions, 

costs, and other effects (if any) of 

successively more stringent control 

options. Under such an approach, States 

would still be required to (1) display all 

of the options and identify the average 

and incremental costs of each option; (2) 

consider the energy and non-air quality 

environmental impacts of each option; 

and (3) provide a justification for 

adopting the technology selected as the 

‘‘best’’ level of control, including an 

explanation of its decision to reject the 

other control technologies identified in 

the BART determination. 

In selecting a ‘‘best’’ alternative, the 

proposed guidelines included a 

discussion on whether the affordability 

of controls should be considered. As a 

general matter, for plants that are 

essentially uncontrolled at present and 

emit at much greater levels per unit of 

production than other plants in the 

category, we believe it is likely that 

additional control will be cost-effective. 

The proposed guidelines noted, 

however, that we recognize 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. 

We did not intend, for example, that the 

most stringent alternative must always 

be selected if that level would cause a 

plant to shut down, while a slightly 

lesser degree of control would not have 

this effect. 

Comments. We received comments 

supporting both of the approaches for 

evaluating ranked control alternatives. 

Many commenters, including 

commenters from State agencies, were 

supportive of the first approach. 

Comments from State air quality 

agencies were strongly supportive of 

this approach. These commenters 

believed that this approach is consistent 

with past approaches by States for 

considering control options for case-bycase determinations, is well understood 

by all parties, and thus easier to 

implement. The first approach also was 

strongly supported in comments from 

environmental organizations and private 

citizens. Some comments noted that the 

plain terminology ‘‘best’’ suggests that 

there must be a sound reason for not 

using the most stringent control level. 

Many comments from industrial trade 

organizations were critical of the first 

approach and believed that any 

requirement to use this approach would 

reduce State discretion because this 

approach, in the judgment of the 

commenters, would amount to use of 

the most stringent alternative as a 

default. Some of these comments 

asserted that the approach in option 1 

would shift the BART analysis away 

from a cost-benefit approach mandated 

by the CAA towards a BACT-like 

technology analysis. Other commenters 

believed that EPA should recognize that 

BART, as a control requirement for 

retrofitting existing sources, should 

differ from BACT or other controls for 

new equipment. A number of 

comments, in supporting the second 

approach, believed that this approach 

provides greater consideration of the 

incremental cost of each succeeding 

option.

Final rule. In the final guidelines, we 

have decided that States should retain 

the discretion to evaluate control 

options in whatever order they choose, 

so long as the State explains its analysis 

of the CAA factors. We agree with 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39131

commenters who asserted that the 

method for assessing BART controls for 

existing sources should consider all of 

the statutory factors. 

6. What Should Be the Presumptive 

Limits for SO2 and NOX for Utility 

Boilers? 

Background. In the 2004 reproposal, 

we proposed that States, as a general 

matter, should require EGUs greater 

than 250 MW in size at power plants 

larger than 750 MW to control 95 

percent of their SO2 emissions, or 

control to within an SO2 emission range 

of 0.1 to 0.15 lb/mmBtu. We also 

proposed to establish a rebuttable 

presumption that States should impose 

these BART SO2 limits on all EGUs 

greater than 250 MW, regardless of the 

size of the power plant at which they 

are located. 

For NOX, we proposed that sources 

currently using controls such as SCRs to 

reduce NOX emissions during part of the 

year should be required to operate those 

controls year-round. For power plants 

without post-combustion controls, we 

proposed to establish a presumptive 

emissions limit of 0.20 lbs/mmbtu for 

EGUs greater than 250 MW in size. We 

requested comment on the rate of NOX

emissions that can be achieved with 

combustion modifications on specific 

types of boilers. Many commenters 

responded both in favor and in 

opposition to these proposed BART 

presumptive limits. 

Comments. A number of utility 

groups said the presumptive SO2

emissions control approach 

inappropriately ignores the need for a 

visibility impact evaluation which is 

required in step 5 of the proposed caseby-case BART engineering analysis. 

They said that setting presumptive 

limits infringes on a state’s authority to 

establish BART on a case-by-case basis 

considering not only visibility 

improvement, but the other statutory 

factors as well. The commenters said 

that visibility is both Class I area and 

source specific, which is the reason 

Congress gave the States the lead role 

and discretion in the BART program to 

determine which sources need to install 

or upgrade controls. Through the use of 

presumptions and default values, 

however, our prescriptive process, as 

proposed, would make the installation 

of maximum controls more likely 

without regard to visibility benefits. 

Instead, they argued, we should give the 

states maximum flexibility to use the 

five statutory factors in their BART 

determinations. Commenters said 

sources must be allowed to assess the 

visibility improvements of a variety of 

control options. 

Several utilities raised concern that 

sources with existing controls should 

not be required to meet the presumptive 

limits without the chance to evaluate 

the degree of visibility improvement 

expected from the additional emission 

reduction requirements. They said that 

if a source can demonstrate a reduction 

in visibility impairment below the 

specified threshold (whether that 

threshold is our currently proposed 0.5 

deciview or an alternative level) with 

less stringent controls, then neither we 

nor States should impose, by default, 

more stringent reduction requirements. 

Commenters from industry, utilities, 

and States said that we had not 

indicated what previously-controlled 

sources must do to comply with BART, 

while we had determined what controls 

are necessary for uncontrolled sources. 

They were concerned that the 

guidelines would lead States to require 

previously-controlled sources to remove 

the controls and replace them with even 

newer controls at great cost and very 

little, if any, improvement in emission 

levels and visibility in Class I areas. 

Commenters added that States should 

be able to use their discretion to 

determine whether additional controls 

are needed. 

Some commenters were concerned 

that the proposed rule would require 

some plants to install SCR to meet the 

NOX control level proposed, as the 

potential retrofit of SCR technology for 

the BART determination may be 

supported by the degree of visibility 

improvement expected. They said that 

the guidelines indicate that if a State 

finds that a source’s visibility 

contribution warrants the installation of 

SCR, then SCR may be imposed. The 

commenter added, however, that the 

guidelines also need to provide for 

instances where the visibility condition 

warrants a lesser control level than what 

would be achieved by advanced 

combustion control; the commenter 

claimed there was reference to this 

concept in the preamble but not the 

guidelines.

Final rule. In these guidelines, we are 

finalizing specific presumptive limits 

for SO2 and NOX for certain EGUs based 

on fuel type, unit size, cost 

effectiveness, and the presence or 

absence of pre-existing controls. The 

presumptive limits finalized in today’s 

rulemaking reflect highly cost-effective 

technologies as well as provide enough 

flexibility for States to take particular 

circumstances into account. 

The presumptive limits apply to EGUs 

at power plants with a total generating 

capacity in excess of 750 MW. As 

explained in greater detail below, for 

these sources we are establishing a 

BART presumptive emission limit for 

coal-fired EGUs greater than 200 MW in 

size without existing SO2 control. These 

EGUs should achieve either 95 percent 

SO2 removal, or an emission rate of 0.15 

lb SO2/mmBtu, unless a State 

determines that an alternative control 

level is justified based on a careful 

consideration of the statutory factors. 

For NOX, we are establishing a set of 

BART presumptive emission limits for 

coal-fired EGUs greater than 200 MW in 

size based upon boiler size and coal 

type, and based upon whether selective 

catalytic reduction (SCR) or selective 

noncatalytic reduction (SNCR) are 

already employed at the source. See 

section d. below for a table listing those 

specific limits. Based on our analysis of 

emissions from power plants, we 

believe that applying these highly costeffective controls at the large power 

plants covered by the guidelines would 

result in significant improvements in 

visibility and help to ensure reasonable 

progress toward the national visibility 

goal. 

States, as a general matter, must 

require owners and operators of greater 

than 750 MW power plants to meet 

these BART emission limits. We are 

establishing these requirements based 

on the consideration of certain factors 

discussed below. Although we believe 

that these requirements are extremely 

likely to be appropriate for all greater 

than 750 MW power plants subject to 

BART, a State may establish different 

requirements if the State can 

demonstrate that an alternative 

determination is justified based on a 

consideration of the five statutory 

factors. 

In addition, while States are not 

required to follow these guidelines for 

EGUs located at power plants with a 

generating capacity of less than 750 

MW, based on our analysis detailed 

below, we believe that States will find 

these same presumptive controls to be 

highly-cost effective, and to result in a 

significant degree of visibility 

improvement, for most EGUs greater 

than 200 MW, regardless of the size of 

the plant at which they are located. A 

State is free to reach a different 

conclusion if the State believes that an 

alternative determination is justified 

based on a consideration of the five 

statutory factors. Nevertheless, our 

analysis indicates that these controls are 

likely to be among the most costeffective controls available for any 

source subject to BART, and that they 

are likely to result in a significant 

degree of visibility improvement.

The rest of this section discusses 

these presumptive limits for SO2 and 

NOX for EGUs and the additional 

39132 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

54Summary of Technical Analyses for the 

Proposed Rule, Mark Evangelista, U.S. 

Environmental Protection Agency, April 12, 2004, 

Docket No. OAR–2002–0076.

55CALPUFF Analysis in Support of the the June 

2005 Changes to the Regional Haze Rule, U.S. 

Environmental Protection Agency, June 15, 2005, 

Docket No. OAR–2002–0076.

56 Ibid.

57Technical Support Document for BART SO2

Limits for Electric Generating Units, Memorandum 

to Docket OAR 2002–0076, April 1, 2005.

58 Ibid.

59Summary of BART Source Analyses,

Memorandum from Bill Balcke and Doran Stegura, 

Perrin Quarles Associates, Inc., to Chad Whiteman, 

EPA March 24, 2003. See 2001 emissions data in 

BART AR file, attached.

visibility impact and cost-effectiveness 

analyses we have performed since 

proposal of the guidelines in 2004. 

a. Visibility Analysis for SO2 and NOX

Emissions From EGUs. In the 2004 

reproposal, our preliminary CALPUFF 

modeling 54 suggested that controlling a 

single 250 MW EGU at a 90 percent 

level would improve visibility 

substantially from that source. Based on 

the expected degree of improvement in 

visibility and the use of highly effective 

control technologies that are available 

for sources of this capacity and greater, 

we concluded that the specific control 

levels in the proposal were appropriate. 

Even at that level of control however, 

our analysis indicated that emissions 

from the source might still cause a 

perceptible impact on visibility.

Following comments that we had 

ignored the need to consider the degree 

of improvement in visibility which 

could reasonably be anticipated from 

the use of the presumptive control 

technologies, we undertook a more 

comprehensive modeling analysis of the 

anticipated visibility impacts of 

controlling large EGUs. Based on this 

modeling analysis, we anticipate that a 

majority of the currently uncontrolled 

EGUs at power plants covered by the 

guideline are predicted to have 24-hour 

maximum impacts of greater than a 

change of 2 or 3 deciviews.55 Our 

modeling examples included scenarios 

that were representative of typical 

EGUs, but, in our first hypothetical run 

#1, we conservatively assumed SO2

emissions of 10,000 tons per year (TPY) 

and NOX emissions of approximately 

3,500 TPY.56 Such levels of emissions 

are well below those that may be 

expected of an uncontrolled 200 MW 

EGU. The number of days during any 

year that such sources are predicted to 

have visibility impacts of greater than 

0.5 deciviews or even 1.0 deciview were 

29 days and 12 days on average, 

respectively, at 50 km from a 

hypothetical Class I area in the East; if 

the 98th percentile were considered, 

there would be five days above a 1.0 

deciview change.

The modeled emission rates in the 

example were conservative; for much 

larger EGUs with capacities of 750 MW 

or more, and emission rates much 

higher than those which were modeled, 

visibility degradation is expected to be 

far worse. Clearly there is a substantial 

degree of visibility improvement which 

is likely from emission reductions at 

these sources. 

Although we are confident that the 

EGUs for which we are establishing 

presumptive limits each have a 

significant impact on visibility at one or 

more Class I areas, a State retains the 

option and flexibility to conduct its own 

analysis or allow a source to 

demonstrate that it should not be 

subject to BART (based on its visibility 

effects). 

b. BART Presumptive Limits for SO2

From Coal-Fired Units. For currently 

uncontrolled coal-fired EGUs greater 

than 200 MW in size located at power 

plants greater than 750 MW, we are 

establishing a presumptive BART limits 

of 95 percent SO2 removal, or an 

emission rate of 0.15 lb SO2/mmBtu. We 

are not establishing a presumptive limit 

for EGUs with existing post-combustion 

SO2 controls or for EGUs that burn oil. 

In 2004, we proposed presumptive 

limits for SO2 of 95 percent control or 

a comparable performance level of 0.1 to 

0.15 lbs per million BTU as controls that 

would be achievable and cost-effective. 

We requested comment on the removal 

effectiveness of flue gas desulfurization 

(‘‘FGD’’ or ‘‘scrubber’’ controls) for 

various coal types and sulfur content 

combinations. Having considered the 

comments received, we have 

determined that there is ample data to 

support the determination that the 

BART presumptive limits outlined in 

today’s action are readily achievable by 

new wet or semi-dry FGD systems 

across a wide range of coal types and 

sulfur contents based on proven 

scrubber technologies currently 

operational in the electric industry.57

We agree with the commenters who 

stated that our dual recommendation 

provided equity across sources burning 

coals of varying sulfur content. We 

believe the presumptive limits provide 

enough flexibility that absent unique 

circumstances, any BART-eligible coalfired EGU will be able to achieve one of 

the limits with a new FGD system. We 

expect that BART-eligible EGUs burning 

medium to high sulfur coal will be able 

to achieve a removal efficiency of 95 

percent in a cost effective manner by 

utilizing various wet FGD technologies, 

and that those EGUs burning lower 

sulfur coals could meet the emission 

limit of 0.15lb/mmBtu in a cost effective 

manner by utilizing dry FGD 

technologies. As described below, EPA’s 

unit specific economic modeling 

showed that the majority of BART 

eligible units greater than 200 MW can 

meet the presumptive BART limit at a 

cost of $400 to $2000 per ton of SO2

removed. 

Some commenters expressed concerns 

that the proposed limits were too 

stringent in particular for: (1) EGUs less 

than 750 MW in size, (2) EGUs burning 

low sulfur coals, and (3) EGUs burning 

lignite coals. However, numerous 

examples exist of smaller EGUs and 

EGUs burning low sulfur or lignite coals 

achieving these SO2 limits at reasonable 

cost.58 We recognize that semi-dry FGD 

systems are most commonly utilized on 

units burning lower sulfur coals and are 

not typically designed for removal 

efficiencies of 95 percent or greater. 

However, we believe that most of these 

EGUs can readily achieve the 

presumptive emission rate limit of 0.15 

lb SO2/mmBtu. An analysis of EPA’s 

RACT/BACT/LEAR Clearinghouse Dry 

FGD cost effectiveness data ranged from 

$393 to $2132 per ton SO2 removed, 

with an average cost effectiveness of 

$792 per ton.59

We received a few comments 

expressing the belief that the 

presumptive limits should be more 

stringent, given that BART emission 

limits will not be fully implemented 

until 2013 or 2014. We recognize that 

while some scrubber units currently 

achieve reductions greater than 95 

percent, not all units can do so. The 

individual units that currently achieve 

greater than 95 percent control 

efficiencies do not necessarily represent 

the wide range of unit types across the 

universe of BART-eligible sources. An 

analysis of the Department of Energy’s 

U.S. FGD Installation Database supports 

our belief that 95 percent removal 

efficiencies would be obtainable by all 

types of EGUs burning medium and 

high sulfur coal by 2014, including 

BART-eligible EGUs. In addition, we 

note that the presumption does not limit 

the States’ ability to consider whether a 

different level of control is appropriate 

in a particular case. If, upon 

examination of an individual EGU, a 

State determines that a different 

emission limit is appropriate based 

upon its analysis of the five factors, then 

the State may apply a more or less 

stringent limit.

Our analysis of presumptive BART 

limits accounted for variations in 

existing SO2 controls. We accordingly 

considered (1) coal-fired EGUs without 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39133

60 Ibid. 61 Ibid.

existing SO2 controls, and (2) coal-fired 

EGUs with existing SO2 controls. This 

analysis consisted of the following key 

elements: (1) Identification of all 

potentially BART-eligible EGUs, and (2) 

technical analyses and industry research 

to determine applicable and appropriate 

SO2 control options, (3) economic 

analysis to determine cost effectiveness 

for each potentially BART-eligible EGU, 

and (4) evaluation of historical 

emissions and forecast emission 

reductions for each potentially BARTeligible EGU.60

We identified 491 potentially BARTeligible coal-fired units based on the 

following criteria: (1) The unit was put 

in place between August 7, 1962 and 

August 7, 1977, and (2) the unit had the 

potential to emit more than 250 tons 

annually of SO2. Our assessment of 

potential controls included various 

industry case studies, technical papers, 

public comments, BACT analyses, and 

historical Acid Rain emissions data. Our 

analysis is described in detail in the 

TSD.61

We calculated cost effectiveness and 

projected SO2 emission reductions on a 

per unit basis based on removal 

efficiencies of 90 percent for dry FGD 

systems, in particular spray dry lime 

systems, and 95 percent for wet FGD 

systems, in particular limestone forced 

oxidation systems. Based on our 

analysis, the average cost effectiveness 

for controlling all BART-eligible EGUs 

greater than 200 MW without existing 

SO2 controls was estimated to $919 per 

ton of SO2 removed. Moreover, the 

range of costs effectiveness numbers 

demonstrates that the majority of these 

units can meet the presumptive limits at 

a cost of $400 to $2000 per ton of SO2

removed.

FIGURE 1 

Unit capacity

(MW) 

Tons (K) of SO2

emitted in 2001 

Percent of BART 

eligible coal-fired 

unit’s 2001 emissions 

Calculated average cost effectiveness for MW 

grouping

($/ton SO2 removed) 

Percent of estimated removable 

BART SO2 emissions from coalfired units* 

<50 MW ............................................................................... 26 0.4 1962 0.9 

50–100 MW ......................................................................... 93 1.4 2399 1.6 

100–150 MW ....................................................................... 171 2.5 1796 2.2 

150–200 MW ....................................................................... 235 3.5 1324 3.4 

200–250 MW ....................................................................... 253 3.8 1282 3.1 

250–300 MW ....................................................................... 281 3.2 1128 4.0 

>300 MW ............................................................................. 5712 85.2 .............................. 84.8 

All Units ................................................................................ 6707 100 984 100 

BART Units (>200MW) ........................................................ 6246 92.2 919 91.9 

In establishing presumptive BART 

limits, we were cognizant of the fact that 

upgrading an existing scrubber system is 

typically considered more cost effective 

than constructing a new scrubber 

system. However, due to the diverse and 

complex nature of upgrading existing 

FGD systems (scrubber type, reagents, 

online year, absorber characteristics, 

current operating procedures, etc.), 

there is no single solution or standard 

appropriate for all EGUs. As a result, we 

are not including specific numerical 

presumptive limits for EGUs with preexisting scrubbers. However, for 

scrubbers currently achieving removal 

efficiencies of at least 50 percent, we 

recommend States evaluate a range of 

scrubber upgrade options available for 

improving the SO2 removal performance 

of existing units. There are numerous 

scrubber enhancements available to 

upgrade the average removal efficiencies 

of all types of existing scrubber systems, 

and the guidelines contains a discussion 

of the options that States should 

evaluate in making BART 

determinations for EGUs with existing 

scrubbers. 

The guidelines do not require EGUs 

with existing FGD systems to remove 

these controls and replace them with 

new controls, but the guidelines do state 

that coal fired EGUs with existing SO2

controls achieving removal efficiencies 

of less than 50 percent should consider 

constructing a new FGD system to meet 

the presumptive limits of 95 percent 

removal or 0.15 lb/mmBtu in addition to 

evaluating the suite of upgrade options. 

For these EGUs, the suite of available 

‘‘upgrades’’ may not be sufficient to 

remove significant SO2 emissions in a 

cost effective manner, and States may 

determine that these EGUs should be 

retrofitted with new FGD systems. 

c. BART Limits for SO2 From Oil-Fired 

Units. We are not establishing a 

presumptive BART limit for SO2 from 

oil-fired EGUs. The guidelines state that 

the most appropriate control option for 

oil-fired EGUs, regardless of capacity, is 

to set limits on the sulfur content of the 

fuel oil burned in the unit. 

Commenters suggested EPA evaluate 

two primary control options for BART 

oil-burning units: (1) Sulfur content fuel 

oil limitations, and (2) flue gas 

desulfurization systems. We have been 

unable to find any FGD application in 

the U.S. electric industry on an oil-fired 

unit. As a result, our analysis for oilfired units focused on benchmarking 

previously imposed fuel oil restrictions 

on the electric industry and (2) a 

regional economic analysis of switching 

from high sulfur to low sulfur fuel oil. 

Our study of currently imposed fuel 

oil restrictions on the electric industry 

suggested that all BART-eligible EGUs 

currently have some sort of imposed 

sulfur content or emission rate 

limitation. Of the 74 BART-eligible oilburning EGUs, 32 currently have sulfur 

fuel oil restrictions of less than 1 

percent, and 67 have some sort of sulfur 

content limitation. In addition, our 

economic analysis suggests that 

switching to low sulfur fuel oil is a cost 

effective method in reducing SO2

emission from oil fired units.

As approximately 43 percent of the 

BART eligible oil units currently have a 

sulfur content limitation that is either 

equivalent to, or more stringent than, 

one percent sulfur by weight, the 

guidelines require States to consider a 

one percent or lower sulfur by weight 

fuel oil restriction on all BART eligible 

EGUs as part of their BART analysis, 

and recommends that States establish 

appropriate and sustainable sulfur 

content fuel oil restrictions, taking into 

39134 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

62See 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.

63The current combustion control technology 

EPA analyzed for cyclone units is coal reburning.

account fuel oil availability. States 

should accordingly evaluate a one 

percent sulfur content limitation as a 

starting point of their BART 

determination for oil-fired EGUs subject 

to BART. 

d. BART Presumptive Limits for NOX

From Coal-fired Units. In the 2004 

reproposal, in discussing NOX controls 

on EGUs, we explained that there are 

two somewhat distinct approaches to 

reducing emissions of NOX at existing 

sources. One is to use combustion 

controls (including careful control of 

combustion air and low-NOX burners). 

The other approach is removal 

technology applied to the flue gas 

stream (such as SCRs and SNCRs). 

For EGUs currently using controls 

such as SCRs or SNCRs to reduce NOX

during part of the year, we are 

establishing a presumption that use of 

these same controls year-round is 

BART. (Some commenters supported 

year-round operation of these controls. 

One commenter suggested the cost of 

year-round operation of SCRs would be 

significant. However, our analysis 

showed year-round operation of existing 

SCRs compared to operation during the 

5-month ozone season only to be highly 

cost effective (average cost-effectiveness 

of $170 per ton).) Although only a few 

BART-eligible sources currently have 

SNCRs installed, we note that States 

may wish to consider SCR as an 

alternative to annual operation of SNCR 

in light of the relatively high operating 

costs associated with SNCR. 

For sources without post-combustion 

controls (i.e., SCRs and SNCRs), we are 

establishing a presumption as to the 

appropriate BART limits for coal-fired 

units based on boiler design and coal 

type. These presumptions apply to 

EGUs greater than 200 MW at power 

plants with a generating capacity greater 

than 750 MW and are based on control 

strategies that are generally costeffective for all such units. 

In 2004 we noted that, unlike the 

methods for controlling SO2 (which fall 

within a fairly narrow range of cost 

effectiveness and control efficiencies), 

the removal efficiencies and costs 

associated with the control techniques 

for NOX vary considerably, depending 

on the design of the boiler and the type 

of coal used. In response to comments 

on the proposal, we have performed 

additional analyses of all individual 

BART-eligible coal-fired units 62 and our 

analyses indicated that both cost 

effectiveness and post-control rates for 

NOX do depend largely on boiler design 

and type of coal burned. Based on these 

analyses, we believe that States should 

carefully consider the specific NOX rate 

limits for different categories of coalfired utility units, differentiated by 

boiler design and type of coal burned, 

set forth below as likely BART limits.

In today’s action, EPA is setting 

presumptive NOX limits for EGUs larger 

than 750 MW. EPA’s analysis indicates 

that the large majority of the units can 

meet these presumptive limits at 

relatively low costs. Because of 

differences in individual boilers, 

however, there may be situations where 

the use of such controls would not be 

technically feasible and/or costeffective. For example, certain boilers 

may lack adequate space between the 

burners and before the furnace exit to 

allow for the installation of over-fire air 

controls. Our presumption accordingly 

may not be appropriate for all sources. 

As noted, the NOX limits set forth here 

today are presumptions only; in making 

a BART determination, States have the 

ability to consider the specific 

characteristics of the source at issue and 

to find that the presumptive limits 

would not be appropriate for that 

source.

The table below indicates the types of 

boilers installed at the 491 BARTeligible coal-fired EGUs. Dry-bottom 

wall-fired boiler units and tangentiallyfired boiler units make up a large 

majority of the total BART-eligible 

EGUs.

TABLE 1.—POPULATION OF BART-ELIGIBLE COAL-FIRED EGUS

Boiler type 

Number Number Number 

All units Units > 200 MW 

Units > 200 MW 

at 750 MW 

plants 

Cyclone ............................................................................................................................ 56 35 19 

Cell Burner ....................................................................................................................... 35 35 29 

Dry Bottom—Wall fired .................................................................................................... 188 121 77 

Dry Bottom Turbo-fired .................................................................................................... 14 10 4 

Stoker ............................................................................................................................... 5 0 0 

Tangentially-fired ............................................................................................................. 186 164 112 

Wet Bottom ...................................................................................................................... 6 5 5 

Other ................................................................................................................................ 1 0 0 

Total BART-eligible coal-fired EGUs ........................................................................ 491 370 246 

For all types of boilers other than 

cyclone units, the limits in Table 2 are 

based on the use of current combustion 

control technology. Current combustion 

control technology is generally, but not 

always, more cost-effective than postcombustion controls such as SCRs. For 

cyclone boilers, SCRs were found to be 

more cost-effective than current 

combustion control technology;63 thus 

the NOX limits for cyclone units are set 

based on using SCRs. SNCRs are 

generally not cost-effective except in 

very limited applications and therefore 

were not included in EPA’s analysis. 

The types of current combustion control 

technology options assumed include 

low NOX burners, over-fire air, and coal 

reburning.

We are establishing presumptive NOX

limits in the guidelines that we have 

determined are cost-effective for most 

units for the different categories of units 

below, based on our analysis of the 

expected costs and performance of 

controls on BART-eligible units greater 

than 200 MW. We assumed that coalfired EGUs would have space available 

to install separated over-fire air. Based 

on the large number of units of various 

boiler designs that have installed 

separated over-fire air, we believe this 

assumption to be reasonable. It is 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39135

64No Cell burners, dry-turbo-fired units, nor wetbottom units burning lignite were identified as 

BART-eligible, thus no presumptive limit was 

determined. Similarly, no wet-bottom units burning 

sub-bituminous were identified as BART-eligible.

65These limits reflect the design and 

technological assumptions discussed in the 

technical support document for NOX limits for 

these guidelines, e.g., EPA assumed space would be 

available for over-fire air. 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.

66See 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.

67 Id.

68Reporting requirements for the Acid Rain 

Program and NOX SIP Call affected sources, see 40 

CFR 75 subpart G (parts 7562–64), and EPA Clean 

Air Markets Division Web site, data and maps page 

(http://www.epa.gov/airmarkets).

possible, however, that some EGUs may 

not have adequate space available. In 

such cases, other NOX combustion 

control technologies could be 

considered such as Rotating Opposed 

Fire Air (‘‘ROFA’’). The limits provided 

were chosen at levels that 

approximately 75 percent of the units 

could achieve with current combustion 

control technology. The costs of such 

controls in most cases range from just 

over $100 to $1000 per ton. Based on 

our analysis, however, we concluded 

that approximately 25 percent of the 

units could not meet these limits with 

current combustion control technology. 

However, our analysis indicates that all 

but a very few of these units could meet 

the presumptive limits using advanced 

combustion controls such as rotating 

opposed fire air (‘‘ROFA’’), which has 

already been demonstrated on a variety 

of coal-fired units. Based on the data 

before us, the costs of such controls in 

most cases are less than $1500 per ton.

TABLE 2.—PRESUMPTIVE NOX EMISSION LIMITS FOR BART-ELIGIBLE COAL-FIRED UNITS 64

Unit type Coal type 

NOX presumptive 

limit (lb/

mmbtu) 65

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 

TABLE 3.—AVERAGE COST-EFFECTIVENESS OF NOX CONTROLS FOR BART-ELIGIBLE COAL-FIRED UNITS

Unit type Coal type Number units

nation-wide 

National average 

($/ton) 

Dry-bottom wall-fired ................................................. Bituminous ............................................................... 114 1229 

Sub-bituminous ........................................................ 66 576 

Lignite ....................................................................... 3 1296 

Tangential-fired ......................................................... Bituminous ............................................................... 105 567 

Sub-bituminous ........................................................ 72 281 

Lignite ....................................................................... 9 614 

Cell Burners .............................................................. Bituminous ............................................................... 32 1287 

Sub-bituminous ........................................................ 3 1021 

Dry-turbo-fired ........................................................... Bituminous ............................................................... 7 775 

Sub-bituminous ........................................................ 7 599 

Wet-bottom ................................................................ Bituminous ............................................................... 6 378 

Cyclones (with SCR) ................................................. All ............................................................................. 56 900 

The advanced combustion control 

technology we used in our analysis, 

ROFA, is recently available and has 

been demonstrated on a variety of unit 

types. It can achieve significantly lower 

NOX emission rates than conventional 

over-fire air and has been installed on 

a variety of coal-fired units including Tfired and wall-fired units. We expect 

that not only will sources have gained 

experience with and improved the 

performance of the ROFA technology by 

the time units are required to comply 

with any BART requirements, but that 

more refinements in combustion control 

technologies will likely have been 

developed by that time. As a result, we 

believe our analysis and conclusions 

regarding NOX limits are conservative.66

For those units that cannot meet the 

presumptive limits using current 

combustion control technology, States 

should carefully consider the use of 

advanced combustion controls such as 

ROFA in their BART determination.

A detailed discussion of our analysis 

is in the docket.67 For data on emissions 

and existing control technology in use at 

the BART-eligible EGUs, we used EPA’s 

Clean Air Markets Division database.68

C. Selective Catalytic Reduction (‘‘SCR’’) 

and Cyclone Units 

We also analyzed the installation of 

SCRs at BART-eligible EGUs, applying 

SCR to each unit and fuel type. The 

cost-effectiveness was generally higher 

than for current combustion control 

technology except for one unit type, 

cyclone units. Because of the relatively 

high NOX emission rates of cyclone 

units, SCR is more cost-effective. Our 

analysis indicated that the costeffectiveness of applying SCR on coalfired cyclone units is typically less than 

$1500 a ton, and that the average costVerDate jul<14>2003 19:24 Jul 05, 2005 Jkt 205001 PO 00000 Frm 00033 Fmt 4701 Sfmt 4700 E:\FR\FM\06JYR3.SGM 06JYR3
39136 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

69See 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. 70 Id.

71Section 308(e)(2) was based, in turn, on the 

precedent set by our interpretation of CAA 

169A(b)(2) in a single BART-source context—see 64 

FR 35739, citing Central Arizona Water 

Conservation District, 990 F.2d 1531 (1993).

72 ‘‘Supplemental Air Quality Modeling 

Technical Support Document (TSD) for the Clean 

Air Interstate Rule (CAIR), May, 2004.’’ http://

www.epa.gov/cair/pdfs/saqmtsd.pdf.

effectiveness is $900 per ton.69 As a 

result, we are establishing a 

presumptive NOX limit for cyclone units 

based on the use of SCR. For other units, 

we are not establishing presumptive 

limits based on the installation of SCR. 

Although States may in specific cases 

find that the use of SCR is appropriate, 

we have not determined that SCR is 

generally cost-effective for BART across 

unit types.

Oil and Gas-Fired Units 

For oil-fired and gas-fired units, we 

believe that installation of current 

combustion control technology is highly 

cost-effective and should be considered 

in determining BART for these sources. 

We performed an analysis of BARTeligible oil and gas-fired units similar to 

the analysis done for coal-fired units. 

Our analysis indicated that a number of 

units can make significant reductions in 

NOX emissions which are cost-effective 

through the application of current 

combustion control technology.70

However, for a number of units, the use 

of combustion controls does not appear 

to be cost-effective. As a result, we 

determined that it would be 

inappropriate to establish a general 

presumption regarding likely BART 

limits. As a result, the guidelines only 

indicate that States should consider the 

installation of current combustion 

control technology on oil and gas-fired 

units.

IV. How Does Today’s Rule Affect 

States Options for Using Alternative 

Strategies in Lieu of Source-by-Source 

BART? 

Background 

Over the past several years, there have 

been a number of rule makings and 

court decisions on the subject of BART 

and BART-alternative programs. In 

order to understand today’s actions, it is 

useful to again review the regulatory 

and litigation history, with a specific 

focus on BART-alternative issues. 

As noted in part I of this preamble, 

the 1999 regional haze rule included 

provisions for BART, codified at 40 CFR 

51.308(e), and in definitions that appear 

in 40 CFR 51.301. Among these 

provisions was section 308(e)(2), 

allowing States to implement cap and 

trade programs, or other alternative 

programs, in lieu of BART. Section 

308(e)(2) provided that trading program 

alternatives must be demonstrated to 

achieve greater reasonable progress than 

BART, and provided the general 

parameters for making this 

demonstration. Of particular relevance, 

section 308(e)(2) directed States, in the 

course of estimating emissions 

reductions anticipated from source-bysource BART, to determine what 

comprises BART based on the four nonvisibility factors, and then estimate 

visibility improvements based on the 

application of BART to all sources 

subject to BART. In other words, section 

308(e)(2) indicated that states should 

use what has since been termed a 

‘‘group BART’’ approach to estimating 

the source-by-source BART benchmark, 

for comparison to the alternative 

program. Section (e)(2) did not prescribe 

the specific criteria to be used to 

compare the progress estimated from 

source-by-source BART to that 

anticipated from the trading program. 

The preamble discussion indicated that 

the comparison should be based on both 

emission reductions and visibility 

improvement, but did not provide 

further specificity. See 64 FR at 35741–

35743.

Specific criteria for making the 

comparison to programs was proposed 

in the BART Guidelines (40 CFR 51 

App. Y) in 2001. These criteria—

sometimes referred to as the ‘‘betterthan-BART test’’ consist of the 

following. First, if the geographic 

distribution of emissions reductions 

from the two programs is expected to be 

similar, the comparison can be made 

based on emissions alone. Second, if the 

distribution of emissions reductions is 

anticipated to be significantly different, 

then a two-pronged visibility 

improvement test is employed. The first 

prong is that the alternative program 

must not result in a degradation of 

visibility at any Class I area. The second 

prong is that the alternative program 

must result in greater visibility 

improvement overall, based on an 

average across all affected Class I areas. 

See 66 FR 38133. 

In 2002, the D.C. Circuit decided 

American Corn Growers. The court in 

that decision invalidated ‘‘the BART 

provisions’’ on the basis that EPA had 

improperly constrained State authority 

by requiring them to bifurcate visibility 

from the other statutory factors when 

making BART determinations, and by 

specifying that visibility impairment 

should be considered on a group basis 

when determining whether a BART 

eligible source is subject to BART. 291 

F.3d 1, 8. 

Because EPA’s policy of allowing 

alternative programs to BART was not at 

issue in American Corn Growers, the 

decision contained no discussion of 

how such alternative programs would 

be compared to BART—neither the step 

of estimating emissions from source-bysource BART, nor the criteria for the 

actual comparison (i.e., the test). 

Therefore, EPA interpreted the court’s 

vacature of the BART provisions to 

apply to the source-by-source BART 

regulations under 40 CFR 51.308(e)(1). 

Accordingly, in our May 2004 

reproposal of the BART guidelines, we 

did not propose any changes in section 

308(e)(2), and we retained the section 

on trading programs in the guidelines 

(Appendix Y) as that section was 

proposed in 2001. 

In June 2004, in the Supplemental 

Notice of Proposed Rulemaking (SNPR) 

for the Clean Air Interstate Rule (CAIR), 

we proposed to conclude that the CAIR 

will achieve greater reasonable progress 

than would BART for SO2 and NOX at 

BART-eligible EGUs in CAIR affected 

States and therefore may be treated as a 

program in lieu of BART for those 

sources. In doing so, we discussed 

regional haze rule section 308(e)(2) as 

precedent for the policy of allowing 

trading programs to substitute for 

BART.71 However, noting that the CAIR 

trading program affected only one 

category of BART-eligible sources 

(EGUs), rather than all BART-eligible 

categories as envisioned for Statedeveloped BART-alternative programs 

under section 308(e)(2), we proposed 

adding a 308(e)(3) applicable only to 

CAIR. This section would provide that 

states that comply with the CAIR by 

subjecting EGUs to the EPA 

administered cap and trade program 

may consider BART satisfied for NOX

and SO2 from BART-eligible EGUs. In 

the CAIR SNPR and supporting 

documentation,72 we provided analyses 

demonstrating that CAIR would achieve 

greater emission reductions than BART, 

and would make greater reasonable 

progress according to the two-pronged 

visibility test previously proposed in the 

BART guidelines.

In February 2005, in CEED v. EPA, the 

D.C. Circuit invalidated a BARTalternative program developed by the 

Western Regional Air Partnership 

(WRAP), which was also based on a 

requirement of group-BART analysis in 

setting source-by-source benchmark. It 

is important to note that the twopronged better-than-BART test was not 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39137

at issue in CEED, as neither the States 

nor EPA had employed that test in 

determining that the WRAP’s program 

achieved greater progress than BART. 

The issue on which the court based its 

decision was not how the two programs 

were compared, but how States were 

required to estimate reductions from 

source-by-source BART in order to make 

the comparison. The implications of this 

case to today’s action are discussed in 

more detail below. 

Finally, on March 10, 2005 we 

promulgated the final CAIR. In the final 

CAIR, we presented refined and 

updated analyses continuing to show 

that CAIR makes greater progress than 

BART. We concluded at that time that 

we should defer a final ‘‘better than 

BART’’ determinations until (1) the 

source-by-source BART guidelines for 

EGU were promulgated, and (2) the 

criteria for comparing alternatives to 

BART were also finalized. We are taking 

both of those actions today, and, as 

explained below, are therefore also 

making our final determination that 

CAIR achieves greater progress than 

BART and may be used by States as a 

BART substitute. 

Final Criteria for Comparing Visibility 

Progress of an Alternative Program to 

BART 

Proposed Rule. As noted, the criteria 

for determining if an alternative 

measure achieves greater reasonable 

progress than BART (also known as the 

‘‘better than BART’’ test or the twopronged visibility test) were first 

proposed in the 2001 BART guideline 

proposal and reproposed in the 

identical form in the 2004 BART 

guidelines reproposal. The test appeared 

as an element of the guideline’s 

overview of the steps involved in 

developing a trading program consistent 

with regional haze rule section 

308(e)(2).

Specifically, the guidelines provided 

that States could first look at the 

geographic distribution of emissions 

under the trading program. ‘‘If [the] 

distribution of emissions is not 

substantially different than under 

BART, and greater emissions reductions 

are achieved, then the trading program 

would presumptively achieve ‘‘greater 

reasonable progress.’’ (69 FR at 25231). 

If the distribution of emissions is 

expected to be different, then States are 

directed to conduct an air quality 

modeling study. The guidelines then 

provide that

‘‘[t]he modeling study would demonstrate 

‘‘greater reasonable progress’’ if both of the 

following two criteria are met:

—Visibility does not decline in any Class I 

area, and 

—Overall improvement in visibility, 

determined by comparing the average 

differences over all affected Class I areas

Comments Received 

Several commenters stated that the 

trading criteria contained in the 

proposed BART guidelines were, along 

with other parts of the guidelines, 

beyond EPA’s authority to impose under 

the CAA. 

Several State commenters asked for 

clarification of what should be 

considered a significantly different 

geographic distribution of emission 

reductions, for purposes of proceeding 

to the two-pronged visibility test. 

One comment, submitted by 

environmental groups in response to our 

preliminary application of the twopronged test to the CAIR in the CAIR 

rulemaking, goes to the permissibility of 

that test in general and is therefore 

relevant to the finalization of the test. 

Specifically, these commenters stated 

that because section 169A(b)(2)(A) 

requires BART for an eligible source 

which may reasonably be anticipated to 

cause or contribute to any impairment 

of visibility in any Class I area, EPA is 

without basis in law or regulation to 

base a better-than-BART determination 

on an analysis that uses averaging of 

visibility improvement across different 

Class I areas. 

Final Action. We are amending the 

regional haze rule to incorporate the 

two- prong visibility test as it was 

previously proposed in the BART 

guideline proposals. Specifically, we are 

adding the test to the rule provisions at 

section 51.308(e)(3). 

The EPA has the authority to 

prescribe this methodology under its 

general rulemaking authority provided 

by CAA section 301(a), and under CAA 

sections 169A(4) and 169(e). The latter 

provisions require EPA to promulgate 

regulations to assure reasonable 

progress towards the national visibility 

goal and to assure compliance with the 

requirements of section 169A, which 

include the requirements for BART 

under section 169A(b)(2)(A), and to 

promulgate such measures as may be 

necessary to carry out these regulations. 

The EPA has determined that source-bysource BART need not be required when 

it is not necessary to meet reasonable 

progress because greater progress can be 

achieved by an alternative means. The 

D.C. Circuit in CEED upheld this 

interpretation of the BART provisions’

relationship to the broader reasonable 

progress requirements of the Act. 398 

F.3d at 660. In order to assure that such 

alternative programs meet the 

reasonable progress goals of the CAA, 

EPA has the authority, and perhaps a 

duty, to promulgate regulations 

governing how that determination is 

made. 

Moreover, these requirements for 

making the ultimate comparison 

between an alternative program and 

BART do not affect in any way how 

states make BART determinations or 

how they determine which sources are 

subject to BART. It is in those areas 

where the Act and legislative history 

indicate that Congress evinced a special 

concern with insuring that States would 

be the decision makers. Nothing in 

American Corn Growers or CEED 

suggests that those cases rendered EPA’s 

rulemaking authority under section 

169A(a)(4) completely inoperable in any 

BART context. 

With respect to the use of average 

overall improvement, we explained in 

the CAIR NFR preamble that we 

disagree with comments that CAA 

section 169A(b)(2)’s requirement of 

BART for sources reasonably 

anticipated to contribute to impairment 

at any Class I area means that an 

alternative to the BART program must 

be shown to create improvement at each 

and every Class I Area. Even if a BART 

alternative is deemed to satisfy BART 

for regional haze purposes, based on 

average overall improvement as 

opposed to improvement at each and 

every Class I Area, CAA section 

169A(b)(2)’s trigger for BART based on 

impairment at any Class I area remains 

in effect, because a source may become 

subject to BART based on ‘‘reasonably 

attributable visibility impairment’’ at 

any area. See 40 CFR 51.302. In 

addition, within a regional haze context, 

not every measure taken is required to 

achieve a visibility improvement at 

every class I area. BART is one 

component of long term strategies to 

make reasonable progress, but it is not 

the only component. The requirement 

that the alternative achieves greater 

progress based on the average 

improvement at all Class I areas assures 

that, by definition, the alternative will 

achieve greater progress overall. Though 

there may be cases where BART could 

produce greater improvement at one or 

more class I areas, the no-degradation 

prong assures that the alternative will 

not result in worsened conditions 

anywhere than would otherwise exist, 

and the possibility of BART for 

reasonably attributable visibility 

protects against any potential ‘‘hot 

spots.’’ Taken together, the EPA believes 

these factors make a compelling case 

that the proposed test properly defines 

‘‘greater reasonable progress.’’ The EPA 

anticipates that regional haze 

implementation plans will also contain 

measures addressing other sources as 

39138 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

73The regional haze rule requires States to 

establish reasonable progress goals for each Class I 

area that provide for improvement in visibility for 

the most impaired days and ensure no degradation 

in visibility for the most impaired days. The 

reasonable progress test in the regional haze rule 

remains as a separate test from better than BART. 

The SIPs must contain measures to achieve the 

reasonable progress goal; such measures could 

include not only stationary source programs such 

as BART but also programs to address emissions 

from other types of sources. The no degradation (on 

the 20 percent best days) component of the 

reasonable progress test must still be applied to the 

final future year emissions control strategy. This 

does not directly impact the conclusions of the 

better than BART test.

necessary to make progress at every 

mandatory Federal Class I area.

We are therefore finalizing the test 

criteria in the same form in which they 

were proposed as part of the BART 

guidelines. We also recognize that the 

test criteria leave some terms and 

conditions undefined, and we believe 

States and Tribes should retain the 

discretion to reasonably interpret and 

apply these terms as appropriate to the 

context of the particular program at 

issue. 

First, in the proposed test we did not 

specify the time period which should 

serve as the starting point for 

comparison under the first prong. That 

is, we did not specify whether potential 

degradation should be determined in 

relation to visibility conditions existing 

at the time of the proposed program, or 

in relation to base case visibility 

projections for the time of program 

implementation. While either option is, 

we believe, reasonable, in this 

rulemaking we have used the future 

projected base case, for the following 

reasons. 

The underlying purpose of both 

prongs of the test is to assess whether 

visibility conditions at Class I areas 

would be better with the alternative 

program in place than they would 

without it. The first prong ensures that 

the program does not cause a decline in 

visibility at any particular Class I area. 

It addresses the possibility that the 

alternative program might allow local 

increases in emissions which could 

result in localized degradation. The 

second prong assesses whether the 

alternative program produces greater 

visibility improvement in the aggregate 

than would source specific BART. 

In both cases, the logical reference 

point is visibility conditions as they are 

expected to be at the time of program 

implementation but in the absence of 

the program. This insures that the 

visibility improvements or degradations 

determined are due to the programs 

being compared—source-specific BART 

and the cap-and-trade alternative—and 

not to other extrinsic factors. For 

example, if large increases in wild land 

fires are expected, due to accumulation 

of fuel from past forest management 

practices, a degradation of visibility 

from current conditions may be 

expected. It would be irrational to 

disapprove an alternative program 

because of a modeled degradation from 

current conditions, where that 

degradation is actually anticipated 

because of smoke from such fires—

sources which are not subject to the 

CAA BART provisions. By comparing 

the alternative to future projected 

baseline conditions, such extrinsic 

variables are accounted for. We are thus 

able to ascertain (to the extent possible 

where future projections are concerned) 

whether visibility under the alternative 

would decline at any Class I area, all 

other things being equal. 

Therefore, in applying the test to the 

CAIR, we used the future (2015) 

projected baseline. We believe, 

however, that States should have 

discretion in determining the most 

appropriate baseline for this prong of 

the test, as long as the State’s method is 

reasonable. 

Second, although the proposed test 

indicated that dispersion modeling 

should be used to determine visibility 

differences for the worst and best 20 

percent of days, the guideline did not 

specify the relationship between the 

worst and best days and the two prongs 

of the test. We believe that each prong 

of the test should ideally be based on an 

examination of both the worst and best 

20 percent of days. Thus, under the first 

prong, visibility must not decline at any 

one Class I area on either the best 20 

percent or the worst 20 percent days 73

as a result of implementing the 

alternative program; and, under the 

second prong both the best and worst 

days should be considered in 

determining whether the alternative 

program produces greater average 

improvement.

Third, the proposed guidelines did 

not define ‘‘affected’’ Class I areas for 

purposes of the comparison. In applying 

the test to the CAIR, we considered all 

federal mandatory Class I areas in the 

contiguous 48 States for which data was 

available. The principal Class I areas 

affected by the CAIR are those in the 

eastern U.S., therefore we calculated 

average improvement separately for the 

eastern areas, but also considered affects 

at all Class I areas nationally. We 

believe this was appropriate for a 

federally mandated program of the 

scope and magnitude of the CAIR. 

However, this may not be necessary for 

every BART-alternative program 

developed by States in the future, 

especially if proposed programs are 

limited to smaller geographic areas or 

are limited to source categories having 

significantly less widespread impacts 

than EGUs. In such circumstances, it 

may be reasonable for the States and 

Tribes involved to develop criteria for 

‘‘affected’’ Class I areas. For example, 

the affected region could be considered 

to be the States and Tribes involved in 

the trading program as well as 

immediately adjacent States, or Class I 

areas within adjacent States that are 

within some defined distance of 

participating States. 

With respect to comments on the 

degree of difference in the geographic 

distribution of emissions necessary to 

trigger application of the two prong test, 

we believe it is not necessary for EPA 

to define that in the rule. For our CAIR 

analysis, we explained in the SNPR that 

the fact that CAIR would produce 

greater emissions reductions than BART 

in most States, but less reductions than 

BART in a few States, was sufficient 

reason to employ the two pronged 

visibility test, 69 FR 32704. For other 

programs developed by States, a State 

would have the ability to make a 

reasonable decision as to whether there 

was a sufficient basis to make the 

demonstration that an alternative 

program would be better than BART 

based on modeling of the emissions 

distributions alone, or whether the State 

should proceed with the two-pronged 

visibility test. The State’s discretion is 

subject as always to the condition that 

it must be reasonably exercised, and 

must be supported by adequate 

documentation of the analyses. 

Finally, on a related issue, we note 

that in a separate rule making to follow 

soon after today’s action, we will be 

soliciting comments on whether there 

might be other means of demonstrating 

that an alternative program makes 

greater reasonable progress than BART, 

in addition to the two-pronged visibility 

test we are finalizing in today’s action. 

Such other means might take into 

account additional policy 

considerations, as well as the relative 

degree of visibility improvement of the 

two programs. 

C. Final Determination That CAIR 

Makes Greater Reasonable Progress 

Than BART

Proposal. As noted in the background 

section above, in both the CAIR SNPR, 

and NFR, we discussed the proposed 

approach of allowing States to treat 

CAIR as an in-lieu-of BART program for 

EGUs in CAIR-affected States. In both 

actions, we presented analyses based on 

emission projections and air quality 

modeling showing that CAIR will 

achieve greater reasonable progress 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39139

74Supplemental Air Quality Modeling Technical 

Support Document (TSD) for the Clean Air 

Interstate Rule (CAIR), May, 2004. http://

www.epa.gov/cair/pdfs/saqmtsd.pdf; Demonstration 

that CAIR Satisfies the ‘Better-than-BART’ Test as 

proposed in the Guidelines for Making BART 

Determinations, EPA Docket Number OAR–2003–

0054–YYYY, March 2005. http://www.epa.gov/cair/

pdfs/finaltech04.pdf.

towards the national visibility goal than 

would BART for affected EGUs. These 

analyses were conducted according to 

the criteria for making such ‘‘better than 

BART’’ determinations which had been 

proposed in the BART guidelines, and 

which have now been finalized in the 

regional haze rule at 40 CFR 

51.308(e)(3), as discussed above in 

section IV.B. Below, we briefly recap 

these prior analyses. See 69 FR 32684, 

32702–32707 and 70 FR 25162, 25299–

25304 and associated Technical Support 

Documents 74 for full details.

Scenarios Examined 

The CAIR is applicable to 28 States 

and the District of Columbia and 

requires levels of SO2 and NOX

emissions reductions based on those 

achievable on a highly cost effective 

basis from EGUs. BART, on the other 

hand, is applicable nationwide and 

covers 25 additional industrial 

categories, as well as EGUs, of a certain 

vintage. In our comparison, we sought 

to determine whether the CAIR cap and 

trade program for EGUs will achieve 

greater reasonable progress than would 

BART for EGUs only. Therefore, the 

relevant scenarios to examine were (1) 

SO2 and NOX emissions from all EGUs 

nationwide after the application of 

BART controls to all BART-eligible 

EGUs (‘‘nationwide BART’’), and (2) 

SO2 and NOX emissions from all EGUs 

nationwide after the emissions 

reductions attributable to CAIR in the 

CAIR region and application of BART 

controls to all BART-eligible EGUS 

outside the CAIR region (‘‘CAIR + 

BART’’). The latter scenario reflects the 

fact that source-by-source BART would 

remain a federal requirement outside 

the CAIR region, unless and until it is 

replaced by some other state or federally 

required program. Thus, in order to 

more accurately project CAIR emissions, 

it is necessary to impose BART controls 

outside the CAIR region, to account for 

potential load and emission shifting 

among EGUs. 

In addition to these two scenarios, a 

third was used—the future base case in 

the absence of either program. This 

third scenario was used to ensure that 

CAIR would not cause degradation from 

otherwise existing conditions. See 

section IV.B above for a discussion of 

why the future baseline is an 

appropriate comparison point for the 

first prong of the ‘‘better than BART’’

test. 

At the SNPR stage, a ‘‘CAIR + BART’’

scenario was not available, as the only 

projections available at that time had 

been developed for other purposes. 

Thus, the ‘‘CAIR’’ scenario used then, 

which was based on the Clear Skies 

proposal, was imperfect for purposes of 

this analysis in that it assumed SO2

reductions on a nationwide basis (rather 

than in the CAIR region only) and 

assumed NOX reductions requirements 

in a slightly different geographic region 

than covered by the proposed CAIR. 

For the CAIR NFR, we redid the 

emissions projections for both the 

Nationwide BART and CAIR + BART in 

the West scenarios. For the former, we 

increased the number of BART-eligible 

units included by lowering the assumed 

threshold for BART applicability from 

250 MW capacity for both NOX and SO2

to 100 MW for SO2 and 25 MW for NOX, 

and by reviewing the list of potentially 

BART-eligible EGUs. For the latter 

scenario, we produced emissions 

projections based on application of 

CAIR-level emission reductions in the 

States proposed for inclusion in the 

CAIR in the SNPR. 

Emission Projections. For the analyses 

in both the SNPR and NFR, we used the 

Integrated Planning Model (IPM) to 

estimate emissions expected from the 

scenarios described above. Tables 1 and 

2 present the results from the SNPR and 

NFR, respectively.

TABLE 1.—EGU SO2 AND NOX EMISSIONS—AS PROJECTED IN CAIR SNPR 

[In thousands of tons per year] 

2015 Base case 

EGU emissions 2015 ‘‘CAIR’’ 2015 Modeled nationwide e Bart 

Additional reduction from ‘‘CAIR’’

(nationwide 

BART minus 

‘‘CAIR’’) 

Nationwide SO2 ............................................................................... 9,081 5,260 7,012 1,752 

Nationwide NOX ............................................................................... 3,950 2,248 2,781 533 

TABLE 2.—EGU SO2 AND NOX EMISSIONS—AS PROJECTED IN CAIR NFR 

[In thousands of tons per year] 

2015 Base case 

EGU emissions 

2015 CAIR + 

BART 

2015 Nationwide 

BART 

Additional reduction from CAIR + 

BART (nationwide BART 

minus 

CAIR+BART) 

Nationwide SO2 ............................................................................... 9,084 4,735 7,162 2,427 

Nationwide NOX ............................................................................... 3,721 1,816 2,454 638 

As can be seen in the numbers in the 

right-most column, CAIR produced far 

superior emission reductions to 

nationwide BART, and the superiority 

of CAIR over BART increased between 

the SNPR and NFR projections, when 

the scenarios were corrected to more 

accurately reflect the anticipated reality 

in 2015. 

Air Quality Modeling Results. The 

proposed ‘‘better-than-BART’’ test 

provided that if the distribution of 

emission reductions is substantially the 

same under the alternative program as 

under BART, then the demonstration 

can be made simply by comparing 

emission reductions. If, however, the 

distribution is significantly different, 

39140 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

75See Footnote [74], Supra. 76Eastern Class I areas are those in the CAIR 

affected states, except areas in west Texas which are 

considered western and therefore included in the 

national average, plus those in New England

then visibility modeling is required in 

order to apply the two pronged test 

previously described. As noted above, 

CAIR emission reductions were vastly 

greater than those under BART. 

However, because there were some 

differences in the geographic 

distribution of reductions on a state-bystate basis, in order to be conservative 

we conducted air quality modeling and 

evaluated CAIR under the two pronged 

test. 

Specifically, using the above 

emissions projections, we completed 

numerous air quality modeling runs and 

postprocessing calculations to 

determine the impacts of emissions and 

emissions control strategies on visibility 

in Class I areas. We quantified the 

impacts of the CAIR and BART controls 

on visibility impairment by comparing 

the results of the future-year (2015) base 

case model runs with the results of the 

CAIR + BART and nationwide BART 

control strategy model runs. We 

quantified visibility impacts on the 20 

percent best and 20 percent worst 

visibility days. 

For the SNPR modeling, we used the 

Regional Modeling System for Aerosols 

and Deposition (REMSAD) model to 

calculate these visibility impacts. This 

modeling used base year meteorology 

from 1996. Complete year ambient 

monitoring data, which is necessary to 

model future improvements in 

visibility, was available for 1996 from 

Inter-agency Monitoring of Protected 

Visual Environments (IMPROVE) 

monitors located at 44 Class I areas—13 

within the CAIR region and 31 outside 

of it. 

For the NFR modeling, we used the 

Community Multiscale Air Quality 

(CMAQ) model. The base year 

meteorology used in the CMAQ 

modeling was 2001. This later base year 

enabled us to look at more Class I areas, 

because there were more IMPROVE 

monitors which had complete year data 

for 2001 than there had been in 1996. 

Specifically, 81 of the 110 IMPROVE 

sites have complete ambient air quality 

data for 2001. Moreover, because in 

some cases a given IMPROVE monitor is 

designated as representing more than 

one Class I area, these 81 sites are 

representative of 116 Class I areas. 

Twenty nine of the 116 are in the East 

(east of 100 degrees longitude) and 87 

are in the West. 

Using the modeling results, we then 

applied the two prong better than BART 

test which had been defined in the 

proposed BART rule. As explained 

above, under the first prong, visibility 

must not decline at any Class I area, as 

determined by comparing the predicted 

visibility impacts at each affected Class 

I area under the (CAIR) trading program 

with future base case visibility 

conditions. Under the second prong, 

overall visibility, as measured by the 

average improvement at all affected 

Class I areas, must be better under the 

trading program than under sourcespecific BART. The future year air 

quality modeling results were used to 

make this demonstration. 

The visibility impacts of the CAIR + 

BART scenario were compared to base 

case 2015 visibility conditions (without 

CAIR or BART) to determine whether 

the CAIR resulted in a degradation of 

visibility at any Class I area. We also 

compared these visibility impacts with 

the visibility impacts of nationwide 

BART implementation, to assess 

whether the proposed CAIR would 

result in greater average visibility 

improvement than nationwide BART. 

The CAIR passed the first prong by 

not causing a degradation of visibility at 

any Class I area, either in the West or 

nationally. This was true in both the 

SNPR and NFR modeling. The visibility 

projections for each Class I area are 

presented in the respective TSD’s.75

The overall results are presented in 

tables 3 and 4 below, representing the 

SNPR and NFR modeling respectively.

TABLE 3.—AVERAGE VISIBILITY IMPROVEMENT IN 2015 VS. 2015 BASE CASE (DECIVIEWS) AS MODELED USING REMSAD 

IN CAIR SNPR 

Class I areas 

‘‘CAIR’’ Scenario Nationwide BART 

East 76 National East National 

20 percent Worst Days .................................................................................... 2.0 0.7 1.0 0.4 

20 percent Best Days ...................................................................................... 0.7 0.2 0.4 0.1 

TABLE 4.—AVERAGE VISIBILITY IMPROVEMENT IN 2015 VS. 2015 BASE CASE (DECIVIEWS) AS MODELED USING CMAQ IN

CAIR NFR 

Class I Areas 

CAIR + BART in West Nationwide BART 

East 76 National East National 

20 percent Worst Days .................................................................................... 1.6 0.5 0.7 0.2 

20 percent Best Days ...................................................................................... 0.4 0.1 0.2 0.1 

As can be see from the tables, 

although the models produced different 

absolute values, in both cases CAIR 

produced significantly greater visibility 

improvement than nationwide BART. 

For example, looking at the 20 percent 

worst days at Eastern Class I areas (the 

areas most influenced by the CAIR, 

since it is an eastern program), in both 

cases the visibility improvements from 

CAIR were at least twice as great as 

under nationwide BART (i.e., in the 

SNPR, 2.0 deciviews compared to 1.0 

deciviews improvement, and in the 

NFR, 1.6 deciviews compared to 0.7 

deciviews improvement).

This historical overview is given in 

the interest of providing a more 

complete understanding of the analyses 

presented at various stages in the CAIR 

rule making progress. In the end, 

however, it is the analyses presented in 

the CAIR NFR on which we are basing 

our determination that CAIR makes 

greater reasonable progress towards the 

national visibility goals than does 

nationwide BART. Therefore, these NFR 

results are examined more closely in the 

‘‘Final Action’’ section below, in light of 

additional emissions projections we 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39141

have conducted to insure that changes 

to the CAIR and BART rules made 

subsequent to the CAIR NFR do not 

affect that determination. 

Comments Received and EPA’s 

Responses 

Although many comments were 

received regarding our proposal to 

determine that CAIR makes greater 

reasonable progress than BART, nearly 

all of them related either to the terms of 

the test itself, or to policy and legal 

implications of allowing CAIR required 

reductions to substitute for source-bysource BART. These are addressed in 

sections B (above ) and D (below) 

respectively. One commenter asserted, 

with respect to modeling presented in 

the SNPR, that the improvement of 

CAIR compared to source-specific BART 

is so slight it may be potentially within 

the margin of error, and therefore 

insufficient for the better than BART 

demonstration, or for assuring that no 

hot spots will occur. 

The EPA disagrees that the difference 

between CAIR and BART in the SNPR 

visibility projections was not 

significant. The visibility results 

presented in the NFR continue to show 

that the CAIR cap and trade program 

with BART in the non-CAIR region 

provides considerably more visibility 

improvement compared to nationwide 

BART (for EGUs only). The NFR 

modeling results show that the average 

visibility improvement from CAIR on 

the 20 percent worst days at 29 Eastern 

Class I areas is 1.6 deciviews (dv) 

compared to only a 0.7 dv improvement 

from nationwide BART controls. In the 

‘‘better than BART’’ TSD we have 

provided modeling results for 116 

individual Class I areas. The modeling 

shows that CAIR will not create any 

‘‘hot spots.’’ On the 20 percent worst 

days, all of the Eastern Class I areas 

show more visibility improvement 

under CAIR+BART than under BART 

alone. In many of the Western Class I 

areas, nationwide BART and CAIR + 

BART in the West provide about the 

same visibility benefits. (This is to be 

expected, since the CAIR is only 

applicable in the East.) While the 

visibility benefits are similar in the West 

(outside of the CAIR region), they are 

clearly not similar in the East, where the 

CAIR is predicted to achieve twice as 

much visibility improvement compared 

to BART. 

Final action. The CAIR vs. BART 

comparison presented in the CAIR NFR 

was developed while both rules were 

under development and therefore 

subject to change. Since the emissions 

projections and air quality modeling 

presented in the CAIR NFR was 

completed, several changes were, in 

fact, made to the CAIR region. In 

addition, since that time our 

assumptions regarding the likely 

maximum BART emission reductions 

from EGUs also changed. Therefore, we 

recalculated the emission projections to 

see if the rule changes could possibly 

affect the determination that CAIR will 

achieve greater reasonable progress than 

BART. 

Most significantly, the final CAIR 

included Arkansas, Delaware, and New 

Jersey only for purposes of significant 

contribution to ozone non-attainment by 

summertime NOX emissions, whereas 

our modeling had been based on the 

assumption that these States would be 

included for contribution to PM2.5 nonattainment by SO2 and NOX emissions. 

The new emission projections are based 

on the application of CAIR only for 

ozone in these States. 

With respect to the nationwide BART, 

for SO2 the NFR projections assumed 

the application of a 90 percent control 

or 0.10 lbs/mmBtu at uncontrolled 

EGUs greater than 100 MW. In the new 

projections, the control assumptions 

were changed to 95 percent or 0.15 lbs/

mmbtu, to reflect the presumptive 

control levels in the final BART 

guidelines. For NOX, the NFR 

projections were based on an assumed 

emission rate of 0.2 lbs/mmBTU at all 

BART eligible EGUs nationwide. The 

new projections are based on the 

assumption of combustion controls on 

all BART eligible units except cyclones 

which have SCR, and the operation of 

all existing SCR and SNCRs annually, 

instead of just in the ozone season. 

Finally for both pollutants, the 

threshold for application of controls was 

increased to 200 MW, to better reflect 

the presumptions included in the final 

BART guidelines. 

We used IPM to project 2015 

emissions given these new parameters. 

The results are presented in Table 5 

below, which also includes the CAIR 

NFR projections (as reported in Table 2) 

for the reader’s convenience.

TABLE 5.—EGU SO2 AND NOX EMISSIONS—AS PROJECTED IN CAIR NFR AND AS PROJECTED IN SUBSEQUENT UPDATE

(In thousands of tons per year) 

2015 CAIR + 

BART 

2015 Nationwide 

BART 

Additional reduction from CAIR + 

BART (nationwide BART 

minus 

CAIR+BART) 

CAIR NFR: 

Nationwide SO2 ........................................................................................................ 4,735 7,162 2,427 

Nationwide NOX ....................................................................................................... 1,816 2,454 638 

Updated Projections: 

Nationwide SO2 ........................................................................................................ 5,042 7,953 2,911 

Nationwide NOX ....................................................................................................... 2,000 2,738 738 

The updated emissions estimates for 

both the BART and CAIR with BART in 

the West scenarios are slightly higher 

than the NFR emissions estimates, but 

the difference between the CAIR + 

BART and nationwide BART scenarios 

are even larger compared to the NFR 

determination. For SO2, the updated 

CAIR + BART achieves about 2.9 

million tons more reductions than 

updated nationwide BART in 2015. For 

NOX, the updated CAIR + BART policy 

is projected to result in about 738,000 

tons more emissions reductions than the 

updated BART nationwide policy in 

2015. The difference between the 

updated CAIR + BART and nationwide 

BART scenarios is now larger by 

484,000 tons of SO2 reduction (i.e., 

2,911,000 ¥ 2,427,000) and 100,000 

tons of NOX reduction (i.e. 738,000 ¥

638,000). 

Implications of New Emission 

Projections for the Two-Pronged Test 

The first prong of the better than 

BART test specifies that no degradation 

of visibility can occur at any Class I 

area. In order to be sure that Class I 

areas do not experience a degradation in 

39142 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

77The 1,000 ton per year increase in NOX in 

Connecticut represents approx. 0.003 percent of the 

total EGU NOX in the 2015 base case and the 2,000 

ton per year increase in SO2 in New Jersey 

represents approx. 0.0005 percent of the total EGU 

SO2 . Since the impacts on visibility from EGU SO2

and NOX are generally regional in nature, we would 

expect this small increase to have little or no impact 

on visibility in any Class I area.

78The difference between the updated CAIR + 

BART and nationwide BART scenarios is larger 

than the difference between the modeled CAIR + 

BART and nationwide BART scenarios. The 

‘‘difference of the differences’’ is 485,000 tons of 

SO2 and 100,000 tons of NOX.

79California, Delaware, Florida, Georgia, Iowa, 

Louisiana, Michigan, Mississippi, Missouri, North 

Carolina, Texas, and Wisconsin.

80There were also four States where BART NOX

emissions reductions were slightly higher than 

CAIR + BART (a total of 4,000 tons per year). Those 

States are Connecticut, Delaware, New Jersey, and 

Oklahoma.

81Alabama, Louisiana, Michigan, Mississippi, 

Missouri, New Jersey, North Carolina, Texas, 

Wisconsin.

82We performed a similar analysis using 

projections including the Clean Air Mercury Rule, 

CAMR, which was promulgated after the CAIR 

NFR. The CAMR emission projections show slight 

additional emission reductions of SO2 and NOX as 

compared to the projections CAIR + BART without 

CAMR, and are nearly identical in terms of 

geographic distribution. Therefore CAIR + BART + 

CAMR, like CAIR + BART, passes the two-pronged 

test for demonstrating greater reasonable progress 

than BART. This is discussed in more detail in the 

TSD accompanying today’s action.

83A geographic enhancement is a method, 

procedure, or process to allow a broad regional 

strategy, such as the CAIR cap & trade program, to 

accommodate BART for reasonably attributable 

impairment. For example, it could consist of a 

methodology for adjusting allowance allocations at 

a source which is required to install BART controls.

visibility, we examined the updated 

State by State emissions estimates. 

Compared to the 2015 base case, in the 

updated CAIR + BART case, there are no 

individual Statewide increases in either 

SO2 or NOX (except for a very small 

∼1,000 ton increase in NOX in 

Connecticut and 2,000 ton increase in 

SO2 in New Jersey).77 That is consistent 

with the NFR CAIR + BART case in 

which no degradation was found. 

Consequently we have determined that 

no degradation would occur under the 

updated CAIR + BART emissions 

scenario.

The second prong of the better than 

BART test specifies a greater average 

visibility improvement from the CAIR 

trading program (CAIR + BART). The 

average visibility improvement from the 

NFR CAIR + BART case was much 

greater (on the 20 percent worst 

visibility days) than the nationwide 

BART case. In the scenario we modeled 

for the NFR, the larger visibility 

improvement from CAIR + BART was 

achieved by reducing SO2 emissions by 

an additional ∼2.4 million tons per year 

compared to nationwide BART and NOX

emissions by an additional 638,000 tons 

per year compared to natiowide BART. 

In the updated scenario, the emissions 

difference between the CAIR + BART 

and nationwide BART cases are even 

larger (2.9 million tons of SO2 and 

738,000 tons of NOX).78 The distribution 

of emission reductions changed 

somewhat in the new projections—that 

is, some States saw a larger difference 

between CAIR and BART, while in other 

States the difference was smaller. The 

largest change was in Kentucky, where 

the new projections showed that 

emission reductions from CAIR were 

even greater than those from BART by 

an additional 200,000 tons per year. 

Among States where the change 

between projections went the other 

direction—that is, showing that BART 

reductions were closer to CAIR 

reductions than previously projected—

the greatest changes were in Alabama 

and Pennsylvania, where the difference 

between the programs decreased by 

46,000 and 45,000 tons, respectively.

Perhaps more importantly, in the new 

projections, there are fewer States in 

which BART reductions are greater than 

CAIR reductions. In the NFR 

projections, there were 12 States 79

where nationwide BART SO2 reductions 

were greater than CAIR + BART 

reductions.80 In those 12 States, BART 

emissions achieved approx. 686,000 

more tons of SO2 reduction compared to 

CAIR + BART. In the rest of the States, 

CAIR + BART achieved an additional 

3.1 million tons per year of SO2

reduction compared to BART. All told, 

the modeling showed that visibility 

improvement was greater under the 

CAIR than under BART on an overall 

average basis, both at eastern Class I 

areas and at all Class I areas nationally. 

In the new projections, CAIR + BART 

achieved an additional 3.4 million tons 

per year of SO2 reduction compared to 

BART in 39 of the 48 States. In the 

remaining 9 States 81 BART achieved 

approx. 472,000 more tons of SO2

reduction compared to CAIR + BART in 

the west.82

Due to the fact that the new 

projections show that the difference 

between CAIR and BART reductions is 

even greater than previously estimated, 

and the visibility improvements due to 

CAIR + BART were previously modeled 

to be much larger than BART, we can 

state with a high degree of confidence 

that the updated CAIR + BART scenario 

passes the second prong of the better 

than BART test. 

D. Revision to Regional Haze Rule To 

Allow CAIR States To Treat CAIR as a 

BART-Substitute for EGUs 

In the SNPR, we proposed that States 

which adopt the CAIR cap and trade 

program for SO2 and NOX would be 

allowed to treat the participation of 

EGUs in this program as a substitute for 

the application of BART controls for 

these pollutants at affected EGUs. To 

implement this, we proposed an 

amendment to the Regional Haze Rule 

which would add a subpart 40 CFR 

51.308(e)to read as follows:

A State that opts to participate in the Clean 

Air Interstate Rule cap-and-trade program 

under part 96 AAA–EEE need not require 

affected BART-eligible EGUs to install, 

operate, and maintain BART. A State that 

chooses this option may also include 

provisions for a geographic enhancement to 

the program to address the requirement 

under § 51.302(c) related to BART for 

reasonably attributable impairment from the 

pollutants covered by the CAIR cap and trade 

program.83

We proposed that this would be 

codified at 40 CFR 51.308(e)(3); 

however, that section now incorporates 

the ‘‘better than BART’’ test as 

discussed above. In today’s action, as 

described below we are finalizing this 

provision of the rule, where it will be 

codified as section 308(e)(4). 

The EPA’s authority to treat emissions 

reductions required by the CAIR as 

satisfying BART was not affected by 

CEED. As noted, the D.C. Circuit in 

CEED upheld the proposition that EPA 

can approve implementation plans 

which rely on alternative strategies to 

BART, as long as greater reasonable 

progress is achieved. CEED, 398 F.3d at 

660. Moreover, the CAIR program is not 

infected in any way with the ‘‘group 

BART’’ methodology held invalid by the 

court. That is because CAIR emission 

reductions levels were not based on the 

invalid ‘‘group-BART’’ approach or any 

other assumptions regarding BART, but 

were developed for other reasons. 

Specifically, the CAIR was developed to 

assist with attainment of the NAAQS for 

PM2.5 and ozone. Had EPA not 

performed the comparison of CAIR to 

BART for visibility progress purposes, 

the CAIR emission reduction 

requirements would remain unchanged. 

Therefore, EPA is not imposing an 

invalid BART requirement on States, 

but rather allowing States, at their 

option, to utilize the CAIR cap and trade 

program as a means to satisfy BART for 

affected EGUs. 

We received numerous comments on 

this proposal, which are summarized 

along with our responses in the CAIR 

NFR preamble at 70 FR 25300–25302 

and in the Response to Comment 

document. To summarize our responses 

to some of the most important 

comments: 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39143

84See Memorandum from Lydia Wegman and 

Peter Tsirigotis, 2002 Base Year Emission Inventory 

SIP Planning: 8-hr Ozone, PM2.5, and Regional Haze 

Programs, November 8, 2002. http://www.epa.gov/

ttn/oarpg/t1/ memoranda/2002bye_gm.pdf.

85Similar to the BART factors, the reasonable 

progress factors are: the cost of compliance, the 

time necessary for compliance, the energy and 

nonair quality environmental impacts of 

compliance, and the remaining useful life of any 

existing sources subject to such requirements.

(1) We note that we are not 

constraining the discretion of States to 

determine which sources are subject to 

BART and to make BART 

determinations. CAIR-affected States are 

not required to accept our determination 

that CAIR may substitute for BART. 

Under the amended rule, States simply 

have the option of accepting this 

determination. 

(2) The EPA does not believe that 

anything in the CAA or relevant case 

law prohibits a State from considering 

emissions reductions required to meet 

other CAA requirements when 

determining whether source by source 

BART controls are necessary to make 

reasonable progress. Whatever the origin 

of the emission reduction requirement, 

the relevant question for BART 

purposes is whether the alternative 

program makes greater reasonable 

progress. As discussed above, EPA has 

determined that CAIR does so with 

respect to SO2 and NOX from EGUs in 

the CAIR region. 

Moreover, the fact that BART and 

CAIR originate from different provisions 

of the CAA does not mean that CAIR 

and BART emissions reductions would 

be additive if BART-eligible EGUs in the 

CAIR program were required to install 

and operate BART. Such source specific 

control requirements would simply 

result in a redistribution of emission 

reductions, as other EGUs could buy the 

excess allowances generated by the 

installation of controls at BART units. 

The net result would be the same level 

of emission reductions, but at a higher 

total cost, because the ability of the 

market to find the most cost effective 

emission reductions would be 

constrained. 

(3) Although regional haze rule 

section 308(e)(2) is not directly 

applicable, as the CAIR is covered by 

the special provision newly codified at 

section 308(e)(4), this determination is 

consistent with the policy contained in 

section 308(e)(2) requiring in-lieu of 

BART programs be based on emissions 

reductions ‘‘surplus to reductions 

resulting from measures adopted to 

meet requirements as of the baseline 

date of the SIP.’’ The baseline date for 

regional haze SIPs is 2002;84 therefore 

CAIR reductions are surplus to 

requirements as of that year.

(4) We agree with commenters that it 

was premature to make a final 

determination whether CAIR makes 

greater reasonable progress than BART 

in the final CAIR because at that time 

the BART guidelines and the criteria for 

making such determinations had not 

been finalized. In today’s action, both 

those rule makings are complete and 

therefore such a determination is ripe. 

(5) We disagree with commenters who 

thought that CAIR should be considered 

‘‘better than BART’’ regardless of 

whether a State participates in the cap 

and trade program. Our demonstration 

that CAIR makes greater reasonable 

progress than BART is based only on an 

examination of emissions reductions 

from EGUs under both programs. The 

CAIR emissions projections and 

modeling assumes that EGU emissions 

will be capped at the levels specified in 

the CAIR. Therefore, States that choose 

to meet their CAIR emission reduction 

requirements in a manner other than 

through the participation of EGUs in the 

CAIR cap and trade program would 

have to develop an appropriate 

demonstration that the measures they 

employ make greater reasonable 

progress than would BART for any 

affected source categories, if the State 

wanted its CAIR-required reductions to 

substitute for source-by-source BART. 

(6) We disagree with commenters who 

asserted that CAIR should satisfy BART 

for States that are subject to CAIR only 

for ozone season NOX. We explained in 

the final CAIR preamble that a State 

subject to CAIR for NOX purposes only 

would have to make a supplementary 

demonstration that BART has been 

satisfied for SO2, as well as for NOX on 

an annual basis. We wish to clarify here 

that a State which is only subject to 

CAIR for NOX, but which also chooses 

to participate in the CAIR trading 

program for both SO2 and NOX, may 

consider BART to be satisfied for both 

SO2 and NOX from EGUs. Because we 

modeled these States as controlling for 

both SO2 and NOX in the CAIR NFR, our 

better than BART demonstration 

presented in that action would be valid 

in that scenario. Conversely, if such 

States choose to participate only in the 

ozone season NOX trading program, the 

updated projections presented in 

today’s action demonstrate that BART 

would be satisfied for NOX, but such 

states would still need to address BART 

for SO2 emissions from EGUs. 

(7) We noted in the final CAIR 

preamble that although we believe it is 

unlikely that a State or FLM will find it 

necessary to certify reasonably 

attributable visibility impairment at any 

Class I area, as a legal matter that 

possibility exists. That is, the 

determination that CAIR makes greater 

reasonable progress than BART is made 

in the context of BART for regional haze 

under CAA 169B, and does not preclude 

a finding of reasonably attributable 

impairment under CAA 169A. The CAIR 

cap and trade program does not include 

geographic enhancements to 

accommodate the situation where BART 

is required based on reasonable 

attribution at a source which 

participates in the trading program, but 

States retain the discretion to include 

such enhancements in their SIPs. 

(8) Our determination that CAIR 

makes greater reasonable progress than 

BART for EGUs is not a determination 

that CAIR satisfies all reasonable 

progress requirements in CAIR affected 

States. Each State, whether in the CAIR 

region or not, is required to set 

reasonable progress goals for each Class 

I area within the State as required in 

regional haze rule section 308(d)(1), and 

to develop long term strategies, 

considering all anthropogenic sources of 

visibility impairing pollutants, as 

required by section 308(d)(3). 

In setting the reasonable progress 

goals, the State is to consider the 

amount of visibility improvement 

needed to achieve a uniform rate of 

progress towards natural background 

conditions in the year 2064. (This 

uniform rate of progress is sometimes 

referred to as the default glide-path). 

The State is also to consider the 

statutory reasonable progress factors 

contained in CAA section 169A(g)(1).85

In doing so, we anticipate that States 

will take into account the degree to 

which CAIR emissions reductions are 

projected to bring visibility conditions 

at its Class I areas in line with the 

default glide path. In some States, the 

improvements expected from CAIR, 

combined with the application of the 

reasonable progress factors to other 

source sectors, may result in a 

determination that few additional 

emissions reductions are reasonable for 

the first long term strategy period. 

Nonetheless, each State is required to 

set its reasonable progress goals as 

provided by the regional haze rule and 

cannot assume that CAIR will satisfy all 

of its visibility-related obligations. 

V. Statutory and Executive Order 

Reviews 

A. Executive Order 12866: Regulatory 

Planning and Review 

Under Executive Order 12866 (58 FR 

51735, October 4, 1993), EPA must 

determine whether the regulatory action 

is ‘‘significant’’ and, therefore, subject to 

Office of Management and Budget 

39144 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

86These levels are commonly achievable by flue 

gas desulfurization controls (‘‘scrubbers’’).

(OMB) review and the requirements of 

the Executive Order. The Order defines 

‘‘significant regulatory action’’ as one 

that is likely to result in a rule that may: 

(1) Have an annual effect on the 

economy of $100 million or more or 

adversely affect in a material way the 

economy, a sector of the economy, 

productivity, competition, jobs, the 

environment, public health or safety, or 

State, local, or Tribal governments or 

communities; 

(2) Create a serious inconsistency or 

otherwise interfere with an action taken 

or planned by another agency;

(3) Materially alter the budgetary 

impacts of entitlements, grants, user 

fees, or loan programs or the rights and 

obligations of recipients thereof; or 

(4) Raise novel legal or policy issues 

arising out of legal mandates, the 

President’s priorities, or the principles 

set forth in the Executive Order. 

Pursuant to the terms of Executive 

Order 12866, it has been determined 

that this rule is a ‘‘significant regulatory 

action,’’ thus EPA has submitted this 

rule to OMB for review. The drafts of 

the rules submitted to OMB, the 

documents accompanying such drafts, 

written comments thereon, written 

responses by EPA, and identification of 

the changes made in response to OMB 

suggestions or recommendations are 

available for public inspection at EPA’s 

Air and Radiation Docket and 

Information Center (Docket Number 

OAR–2002–0076). The EPA has 

prepared the document entitled 

‘‘Regulatory Impact Analysis of the 

Final Clean Visibility Interstate Rule or 

Guidelines for Best Available Retrofit 

Technology Determinations Under the 

Regional Haze Regulations’’ (RIA) to 

address the requirements of this 

executive order. 

1. What Economic Analyses Were 

Conducted for the Rulemaking? 

The analyses conducted for this final 

rule provide several important analyses 

of impacts on public welfare. These 

include an analysis of the social 

benefits, social costs, and net benefits of 

three possible regulatory scenarios that 

States may follow to implement the 

BART rule and guidelines. The 

economic analyses also address issues 

involving requirements of the 

Paperwork Reduction Act (PRA), 

potential small business impacts, 

unfunded mandates (including impacts 

for Tribal governments), environmental 

justice, children’s health, energy 

impacts, and other statutory and 

executive order requirements. 

2. What Are the Benefits and Costs of 

This Rule? 

The benefit-cost analysis shows that 

substantial net economic benefits to 

society are likely to be achieved due to 

reductions in emissions resulting from 

this rule. The results detailed below 

show that this rule would be beneficial 

to society, with annual net benefits 

(benefits less costs) ranging from 

approximately $1.9 to $12.0 billion in 

2015. These alternative net benefits 

estimates reflect differing assumptions 

about State actions taken to implement 

BART and about the social discount rate 

used to estimate the annual value of the 

benefits and costs of the rule. All 

amounts are reflected in 1999 dollars. 

The range of benefits and costs reported 

for the BART represent estimates of 

EPA’s assessment of State actions that 

will likely be taken to comply with the 

BART rule and guidelines. 

a. Control Scenarios 

Today’s rule sets forth presumptive 

requirements for States to require EGUs 

to reduce SO2 and NOX emissions for 

units greater than 200 megawatts (MW) 

in capacity at plants greater than 750 

MW in capacity that significantly 

contribute to visibility impairment in 

Federal Class I areas (national parks). 

The analysis conducted in the RIA 

presents alternative control scenarios of 

possible additional controls for EGUs 

located at plants less than 750 MW in 

capacity. The EPA also calculated the 

amount of SO2 and NOX emissions 

reductions for several illustrative 

scenarios that reflect alternative State 

actions regulating industries with nonEGU sources. The analyses conducted 

include three regulatory alternative 

scenarios that States may choose to 

follow to comply with BART. The 

alternatives include three scenarios of 

increasing stringency—Scenario 1, 

Scenario 2, and Scenario 3. A brief 

discussion of the these alternatives for 

the EGUs and all other sources follows. 

More details of the alternative control 

scenarios and associated control costs 

are discussed in the RIA. 

i. Electric Generating Units 

In the revised BART guidelines, we 

have included presumptive control 

levels for SO2 and NOX emissions from 

coal-fired electric generating units 

greater than 200 megawatts (MW) in 

capacity at plants greater than 750 MW 

in capacity. Given the similarities of 

these units to other BART-eligible coalfired units greater than 200 MW at 

plants 750 MW or less, EPA’s guidance 

suggests that States control such units at 

similar levels for BART. The guidelines 

would require 750 MW power plants to 

meet specific control levels of either 95 

percent control or controls of 0.15 lbs/

MMBtu, for each EGU greater than 200 

MW, unless the State determines that an 

alternative control level is justified 

based on a careful consideration of the 

statutory factors.86 Thus, for example, if 

the source convincingly demonstrates 

unique circumstances affecting its 

ability to cost-effectively reduce its 

emissions, the State may take that into 

account in determining whether the 

presumptive levels of control are 

appropriate for the facility. For an EGU 

greater than 200 MW in size, but located 

at a power plant smaller than 750 MW 

in size, States may also find that such 

controls are cost-effective when taking 

into consideration the costs of 

compliance in the BART analysis in 

applying the five factor test for the 

BART determination. In our analysis we 

have assumed that no additional 

controls will occur where units have 

existing scrubbers and that no controls 

will occur for oil-fired units. While 

these levels may represent current 

control capabilities, we expect that 

scrubber technology will continue to 

improve and control costs will continue 

to decline.

For NOX, for those large EGUs that 

have already installed selective catalytic 

reduction (SCR) or selective noncatalytic reduction (SNCR) during the 

ozone season, States should require the 

same controls for BART. However, those 

controls should be required to operate 

year-round for BART. For sources 

currently using SCR or SNCR for part of 

the year, states should presume that the 

use of those same controls year-round is 

highly cost-effective. For other sources, 

the guidelines establish presumptive 

emission levels that vary depending 

largely upon boiler type and fuel 

burned. For coal-fired cyclone units 

with a size greater than 200 MW, our 

analysis assumes these units will install 

SCR. For all other coal-fired units, our 

analysis assumed these units will install 

current combustion control technology. 

In addition, we assume no additional 

controls for oil and/or gas-fired steam 

units. 

We present alternative regulatory 

scenarios. Scenario 2 represents our 

application of the presumptive limits 

described above to all BART eligibility 

EGUs greater than 200 MW. For 

Scenario 1, we assume that only 200 

MW BART-eligible EGUs located at 

facilities above 750 MW capacity will 

comply with the SO2 requirements and 

NOX controls. In this scenario, no 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39145

facilities less than 750 MW capacity are 

assumed to install BART controls. For 

Scenario 1, we assume that units with 

existing SCRs will operate those SCR 

units year round annually. In contrast in 

Scenario 3, we analyzed SO2 controls 

equivalent to 95 percent reductions or 

0.1 lbs per MMBtu on all previously 

uncontrolled units. NOX controls for 

this most stringent scenario presume 

SCRs will be installed on all units 

greater than 100 MW capacity and 

combustion controls will be installed on 

units greater than 25 MW but less than 

100 MW capacity. The EPA analyzed 

the costs of each BART scenario using 

the Integrated Planning Model (IPM). 

The EPA has used this model 

extensively in past rulemakings to 

analyze the impacts of regulations on 

the power sector. 

The analysis presented assumes that 

BART-eligible EGUs affected by the 

Clean Air Interstate Rule (70 FR 25162) 

have met the requirements of this rule. 

Thus, no additional controls for EGUs 

beyond CAIR are anticipated or 

modeled for the 28 State plus District of 

Columbia CAIR region. In addition, we 

are assuming no additional SO2 controls 

for sources located in States of Arizona, 

Utah, Oregon, Wyoming, and New 

Mexico or Tribal lands located in these 

States due to agreements made with the 

Western Regional Air Partnership 

(WRAP). 

ii. Sources Other Than Electric 

Generating Units 

As previously discussed there are 25 

source categories potentially subject to 

BART in addition to EGUs (referred to 

as non-EGU source categories) as 

defined by the CAA. The EPA evaluated 

a set of SO2 and NOX emission control 

technologies available for these source 

categories and estimated the associated 

costs of control using AirControlNET. 

The control scenarios evaluated reflect 

control measure cost caps of up to 

$1,000 per ton (Scenario 1), $4,000 per 

ton (Scenario 2), and $10,000 per ton 

(Scenario 3). The EPA also conducted a 

cost analysis for control costs of up to 

$2,000 per ton and $3,000 per ton, and 

the results of this analysis are presented 

in the RIA. The analysis consists of 

applying SO2 and NOX controls to each 

non-EGU source category up to the 

specified cost per ton ‘‘cap’’ in each 

scenario. These cost per ton caps are 

specified in average cost terms. As 

control stringency is increased, the 

marginal costs are also estimated for 

each non-EGU source category. The 

scenarios examined are based on the 

costs of technologies such as scrubbers 

for SO2 control, and varying types of 

technologies for NOX control. Scrubbers 

are the most common type of SO2

control for most non-EGU sources for 

each scenario, while combustion 

controls such as low NOX burners (LNB) 

and post-combustion controls such as 

selective noncatalytic reduction (SNCR) 

and selective catalytic reduction (SCR) 

are commonly applicable to most of the 

non-EGU source categories. Combustion 

controls are commonly applied as part 

of Scenario 1, while SNCR and SCR are 

more commonly applied either by 

themselves or in combination with 

combustion controls as part of Scenarios 

2 and 3. Analyses are not available for 

8 of the 25 non-EGU source categories, 

because there are no available control 

measures for these sources or there are 

no sources in these categories included 

in the non-EGU emissions data utilized 

in these analyses. All of these results are 

estimated using a nationwide database 

of BART-eligible non-EGU sources that 

is based on information collected from 

Regional Planning Organizations (RPOs) 

in the fall of 2004.

b. Baseline and Year of Analysis 

The final rule sets forth the guidelines 

for States and Tribes for meeting the 

BART requirements under the CAA and 

the Regional Haze Rule. The Agency 

considered all promulgated CAA 

requirements and known State actions 

in the baseline used to develop the 

estimates of benefits and costs for this 

rule including the recently promulgated 

Clean Air Interstate Rule (70 FR 25162) 

and the proposal to include New Jersey 

and Delaware in the final CAIR region 

for fine particulate matter (70 FR 

25408). However, EPA did not include 

within the baseline the actions States 

may take to implement the ozone and 

PM2.5 NAAQS standards nor the 

recently promulgated Clean Air Mercury 

Rule. No additional SO2 controls were 

assumed for any EGUs within the five 

WRAP States of Utah, Arizona, 

Wyoming, Oregon or New Mexico that 

have existing agreements to achieve 

reduction goals. 

In the analysis, the controls and 

reductions are assumed to be required 

in 2015, a date that is generally 

consistent with the expected timing of 

the rule. States must submit SIPs 

relevant to the BART requirements in 

January 2008. After approval of the SIP, 

there is a 5 year compliance date. Thus, 

controls are likely to be installed and in 

operation by the end of 2013 or the 

beginning of 2014 to comply with the 

rule. In addition, EPA had existing 

inventories, modeling, and base case 

runs for 2015 to use for the analysis. 

The year 2015 is used in this analysis. 

All estimates presented in this report 

represent annualized estimates of the 

benefits and costs of BART in 2015 

rather than the net present value of a 

stream of benefits and costs in these 

particular years of analysis. 

c. Cost Analysis and Economic Impacts 

For the affected region, the projected 

annual private incremental costs of 

BART to the power industry (EGU 

source category) range from $253 to 

$896 million in 2015 depending upon 

the scenario evaluated. These costs 

represent the private compliance cost to 

the electric generating industry of 

reducing NOX and SO2 emissions that 

EPA believes States may require to 

comply with BART. 

In estimating the net benefits of 

regulation, the appropriate cost measure 

is ‘‘social costs.’’ Social costs represent 

the welfare costs of the rule to society. 

These costs do not consider transfer 

payments (such as taxes) that are simply 

redistributions of wealth. The social 

costs of this rule for the EGU sector only 

are estimated to range from 

approximately $119 to $567 million in 

2015 assuming a 3 percent discount 

rate. These EGU sector costs become 

$141 to $688 million in 2015 assuming 

a 7 percent discount rate. 

Overall, the impacts of the BART are 

modest, particularly in light of the large 

benefits we expect. Retail electricity 

prices are projected to increase roughly 

0.1 percent with BART in the 2015 

timeframe under Scenario 2. Coal-fired 

generation, as well as coal production 

and natural gas-fired generation are 

projected to remain essentially 

unchanged as a result of this rule. It is 

also not expected that BART will 

change the composition of new 

generation built to meet growth in 

electricity demand. BART is also not 

expected to impact coal or natural gas 

prices. 

For today’s rule, EPA analyzed the 

costs for the EGU source category using 

the Integrated Planning Model (IPM). 

The IPM is a dynamic linear 

programming model that can be used to 

examine the economic impacts of air 

pollution control policies for SO2 and 

NOX throughout the contiguous U.S. for 

the entire power system. Documentation 

for IPM can be found in the docket for 

this rulemaking or at http://

www.epa.gov/airmarkets/epa-ipm.

The EPA also conducted an analysis 

of State actions in requiring emission 

controls for BART eligible sources in the 

non-EGU source categories. For the 

nation, the projected annual private 

incremental costs range from $150 

million to $2.24 billion for industries 

with affected non-EGU sources. This 

cost range results from different 

assumptions about possible actions 

39146 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

States may take to comply with BART 

and alternative discount rates of 3 and 

7 percent. The non-EGU private 

incremental control cost estimates are 

assumed to approximate the social costs 

of the rule for the non-EGU sector. The 

EPA analyzed the costs to non-EGUs 

sources using AirControlNET. The 

AirControlNET is a software tool that 

can be used to estimate the private costs 

and emission reductions of air pollution 

control policies for SO2, NOX, and other 

criteria pollutants throughout the 

contiguous U.S. for all manufacturing 

industries and many other industries. 

Documentation for AirControlNET can 

be found in the docket for this 

rulemaking or at http://www.epa.gov/

ttn/ecas/AirControlNET.htm.

In summary, the EPA estimates that 

the annual social costs of this rule for 

the EGU and non-EGU source categories 

range from approximately $0.3 to $2.9 

billion annually, based on alternative 

scenarios of State actions in response to 

the BART rule and guidelines assuming 

3 or 7 percent discount rates. Estimates 

are reflected in 1999 dollars. 

d. Human Health Benefit Analysis 

Our analysis of the health and welfare 

benefits associated with this rule are 

presented in this section. Briefly, the 

analysis projects major benefits from 

implementation of the rule in 2015. As 

described below, thousands of deaths 

and other serious health effects would 

be prevented. We are able to monetize 

annual benefits ranging from 

approximately $2.2 to $14.3 billion in 

2015. This range reflects different 

assumptions about States actions in 

response to the BART rule and the 

applicable discount rate (3 percent or 7 

percent).

Table IV–1 presents the primary 

estimates of reduced incidence of PMand visibility-related health effects for 

2015 for the regulatory control strategy 

the EPA expects States may follow to 

comply with BART. In 2015 for 

Scenario 2, we estimate that PM-related 

annual benefits include approximately 

1,600 fewer premature fatalities, 890 

fewer cases of chronic bronchitis, 2,200 

fewer non-fatal heart attacks, 2300 fewer 

hospitalizations (for respiratory and 

cardiovascular disease combined—

admissions and emergency room visits) 

and result in significant reductions in 

days of restricted activity due to 

respiratory illness (with an estimate of 

one million fewer cases) and 

approximately 170,000 fewer work-loss 

days. We also estimate substantial 

health improvements for children from 

reduced upper and lower respiratory 

illness, acute bronchitis, and asthma 

attacks. 

Ozone health-related benefits are 

expected to occur during the summer 

ozone season (usually ranging from May 

to September in the Eastern U.S.). Since 

we did not conduct ozone modeling for 

this rulemaking, we are unable to 

quantify or monetize the ozone related 

benefits that will likely result from 

BART. 

Table IV–2 presents the estimated 

monetary value of reductions in the 

incidence of health and welfare effects. 

Annual PM-related health benefits and 

visibility benefits are estimated to range 

from approximately $2.2 to $14.3 billion 

annually. This range of estimates 

reflects different scenarios about States 

actions in response to the BART rule 

and the applicable discount rate (3 

percent or 7 percent). Estimated annual 

visibility benefits in southeastern and 

southwestern Class I areas range from 

approximately $80 million to $420 

million annually in 2015. All monetized 

estimates are stated in 1999$. These 

estimates account for growth in real 

gross domestic product (GDP) per capita 

between the present and 2015. As the 

table indicates, total benefits are driven 

primarily by the reduction in premature 

fatalities each year. Reductions in 

premature mortality account for over 90 

percent of total benefits. 

Table IV–3 presents the total 

monetized net benefits for 2015. This 

table also indicates with a ‘‘B’’ those 

additional health and environmental 

benefits of the rule that we were unable 

to quantify or monetize. These effects 

are additive to the estimate of total 

benefits. A listing of the benefit 

categories that could not be quantified 

or monetized in our benefit estimates 

are provided in Table IV–4. We are not 

able to estimate the magnitude of these 

unquantified and unmonetized benefits. 

While EPA believes there is 

considerable value to the public for the 

PM-related benefit categories that could 

not be monetized, we believe these 

benefits may be small relative to those 

categories we were able to quantify and 

monetize. In contrast, EPA believes the 

monetary value of the ozone-related 

premature mortality benefits could be 

substantial, but we were unable to 

estimate the benefits for this 

rulemaking. 

e. Quantified and Monetized Welfare 

Benefits

Only a subset of the expected 

visibility benefits—those for Class I 

areas in the southeastern and 

southwestern U.S. are included in the 

monetary benefits estimates we project 

for this rule. We believe the benefits 

associated with these non-health benefit 

categories are likely significant. For 

example, we are able to quantify 

significant visibility improvements in 

Class I areas in the Northeast and 

Midwest, but are unable at present to 

place a monetary value on these 

improvements. Similarly, we anticipate 

improvement in visibility in residential 

areas where people live, work and 

recreate in the nation for which we are 

currently unable to monetize benefits. 

For the Class I areas in the southeastern 

and southwestern U.S., we estimate 

annual benefits ranging from $80 to 

$420 million beginning in 2015 for 

visibility improvements. The value of 

visibility benefits in areas where we 

were unable to monetize benefits could 

also be substantial.

TABLE IV–1.—CLEAN AIR VISIBILITY RULE: ESTIMATED REDUCTION IN INCIDENCE OF ADVERSE HEALTH EFFECTS IN

2015 a,b

Health Effect 

Incidence reduction 

Scenario 1 Scenario 2 Scenario 3 

PM-Related Endpoints: 

Premature mortality c

Adult, age 30 and over ...................................................................................... 400 1,600 2,300 

Infant, age <1 year ............................................................................................ 1 4 5 

Chronic bronchitis (adult, age 26 and over) ............................................................. 230 890 1,300 

Non-fatal myocardial infarction (adults, age 18 and older) ...................................... 570 2,200 3,000 

Hospital admissions—respiratory (all ages) d ........................................................... 140 510 720 

Hospital admissions—cardiovascular (adults, age >18) e ........................................ 120 450 640 

Emergency room visits for asthma (age 18 years and younger) ............................ 370 1,300 1,800 

Acute bronchitis (children, age 8–12) ...................................................................... 550 2,100 3,000 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39147

TABLE IV–1.—CLEAN AIR VISIBILITY RULE: ESTIMATED REDUCTION IN INCIDENCE OF ADVERSE HEALTH EFFECTS IN

2015 a,b—Continued

Health Effect 

Incidence reduction 

Scenario 1 Scenario 2 Scenario 3 

Lower respiratory symptoms (children, age 7–14) ................................................... 6,600 25,000 36,000 

Upper respiratory symptoms (asthmatic children, age 9–18) .................................. 5,000 19,000 27,000 

Asthma exacerbation (asthmatic children, age 6–18) .............................................. 8,100 31,000 44,000 

Work loss days (adults, age 18–65) ........................................................................ 44,000 170,000 240,000 

Minor restricted-activity days (MRADs) (adult age, 18–65) ..................................... 260,000 1,000,000 1,400,000 

a Incidences are rounded to two significant digits. These estimates represent benefits from BART nationwide. The modeling used to derive 

these incidence estimates assumes the final CAIR program in the baseline including the CAIR promulgated rule and the proposal to include SO2

and annual NOX controls for New Jersey and Delaware. Modeling used to develop these estimates assumes annual SO2 and NOX controls for 

Arkansas for CAIR resulting in a slight understatement of the reported benefits and costs for BART. The recently promulgated CAMR has not 

been considered in the baseline for BART. bOzone benefits are expected for BART, but are not estimated for this analysis. 

cAdult premature mortality based upon studies by Pope et al., 2002. Infant premature mortality is based upon studies by Woodruff, Grillo, and 

Schoendorf, 1997. d Respiratory hospital admissions for PM include admissions for chronic obstructive pulmonary disease (COPD), pneumonia, and asthma. e Cardiovascular hospital admissions for PM include total cardiovascular and subcategories for ischemic heart disease, dysrhythmias, and 

heart failure. 

TABLE IV–2. ESTIMATED MONETARY VALUE OF REDUCTIONS IN INCIDENCE OF HEALTH AND WELFARE EFFECTS FOR THE

CLEAN AIR VISIBILITY RULE IN 2015 

[In millions of 1999$] a,b

Scenario 1 Scenario 2 Scenario 3 

Health Effects: 

Premature mortality c,d

Adult >30 years 

3 percent discount rate ........................................................................ $2,330 $9,180 $13,000 

7 percent discount rate ........................................................................ 1,960 7,730 10,900 

Infant <1 year .............................................................................................. 6.12 23.8 34.2 

Chronic bronchitis (adults, 26 and over) ............................................................ 90.5 353 498 

Nonfatal acute myocardial infarctions 

3 percent discount rate ............................................................................... 49.3 189 264 

7 percent discount rate ............................................................................... 45.8 175 245 

Hospital admissions for respiratory causes ....................................................... 1.07 4.03 5.65 

Hospital admissions for cardiovascular causes ................................................. 2.6 10.0 14.1 

Acute bronchitis (children, age 8–12) ................................................................ 0.207 0.79 1.12 

Lower respiratory symptoms (children, 7–14) .................................................... 0.109 0.415 0.587 

Upper respiratory symptoms (asthma, 9–11) ..................................................... 0.137 0.523 0.74 

Emergency Room Visits for Asthma (age 18 years and younger) .................... 0.106 0.362 0.51 

Asthma exacerbations ........................................................................................ 0.367 1.4 1.98 

Work loss days ................................................................................................... 5.56 22.4 31.5

Minor restricted-activity days (MRADs) .............................................................. 13.8 54.1 76.3 

Welfare Effects: 

Recreational visibility, 81 Class I areas ............................................................. 84 239 416 

Monetized Total e

Base Estimate: 

3 percent discount rate ........................................................................ 2,600+B 10,100+B 14,300+B 

7 percent discount rate ........................................................................ 2,200+B 8,600+B 12,200+B 

a Monetary benefits are rounded to three significant digits. These estimates are nationwide with the exception of visibility benefits. Visibility 

benefits relate to Class I areas in the southeastern and southwestern United States. Ozone benefits are expected for BART, but have not been 

estimated for this analysis. The benefit estimates assume the final CAIR program in the baseline that includes the CAIR promulgated rule and 

the proposal to include SO2 and annual NOX controls for New Jersey and Delaware. Modeling used to develop the CAIR baseline estimates assumes annual SO2 and NOX controls for Arkansas resulting in a slight understatement of the reported benefits and costs for BART. The recently 

promulgated CAMR is not considered in the baseline for BART. b Monetary benefits adjusted to account for growth in real GDP per capita between 1990 and the analysis year of 2015. 

cValuation assumes discounting over the SAB-recommended 20-year segmented lag structure described in Chapter 4. Results show 3 percent 

and 7 percent discount rates consistent with EPA and OMB guidelines for preparing economic analyses (U.S. EPA, 2000; OMB, 2003). dAdult premature mortality based upon studies by Pope et al., 2002. Infant premature mortality based upon studies by Woodruff, Grillo, and 

Schoendorf, 1997. eB represents the monetary value of health and welfare benefits not monetized. A detailed listing is provided in Table IV–4. Totals rounded to 

nearest $100 million, and totals may not sum due to rounding. 

TABLE IV–3.—SUMMARY OF ANNUAL BENEFITS, COSTS, AND NET BENEFITS OF THE CLEAN AIR VISIBILITY RULE IN 2015 a

[Billions of 1999$] 

Description Scenario 1 Scenario 2 Scenario 3 

Social costs b

39148 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

TABLE IV–3.—SUMMARY OF ANNUAL BENEFITS, COSTS, AND NET BENEFITS OF THE CLEAN AIR VISIBILITY RULE IN

2015 a—Continued

[Billions of 1999$] 

Description Scenario 1 Scenario 2 Scenario 3 

3 percent discount rate ......................................................................................................... $0.4 $1.4 $2.3 

7 percent discount rate ......................................................................................................... 0.3 1.5 2.9 

Social benefits c, d, e

3 percent discount rate ......................................................................................................... 2.6 + B 10.1 + B 14.3 + B 

7 percent discount rate ......................................................................................................... 2.2 + B 8.6 + B 12.2 + B 

Health-related benefits: 

3 percent discount rate ......................................................................................................... 2.5 9.8 13.9 

7 percent discount rate ......................................................................................................... 2.1 8.4 11.8 

Visibility benefits .......................................................................................................................... 0.08 0.24 0.42 

Net benefits (benefits-costs) e, f

3 percent discount rate ......................................................................................................... 2.2 + B 8.7 + B 12.0 + B 

7 percent discount rate ......................................................................................................... 1.9 + B 7.1 + B 9.3 + B 

aAll estimates are rounded to three significant digits and represent annualized benefits and costs anticipated for the year 2015. Estimates assume a complete CAIR program in the baseline including the CAIR promulgated rule and the proposal to include SO2 and annual NOX controls 

for New Jersey and Delaware. Modeling used to develop the CAIR baseline estimates assumes annual SO2 and NOX controls for Arkansas resulting in a slight understatement of the reported benefits and costs for BART. The recently promulgated CAMR is not considered in the baseline 

for BART. b Note that costs are the annualized total costs of reducing pollutants including NOX and SO2 for the EGU source category in areas outside the 

CAIR region and excluding additional SO2 controls for the WRAP 309 States of UT, AZ, WY, OR or NM and include costs for non-EGU sources 

nationwide. The discount rate used to conduct the analysis impacts the control strategies chosen for the non-EGU source category resulting in 

greater level of controls under the 3 percent discount rate for Scenario 1. cAs this table indicates, total benefits are driven primarily by PM-related health benefits. The reduction in premature fatalities each year accounts for over 90 percent of total monetized benefits in 2015. Benefit estimates in this table are nationwide (with the exception of visibility) and 

reflect NOX and SO2 reductions. Ozone benefits are expected to occur for this rule, but are not estimated in this analysis. Visibility benefits represent benefits in Class I areas in the southeastern and southwestern United States. d Not all possible benefits or disbenefits are quantified and monetized in this analysis. B is the sum of all unquantified benefits and disbenefits. 

Potential benefit categories that have not been quantified and monetized are listed in Table IV–4. eValuation assumes discounting over the SAB-recommended 20-year segmented lag structure described in Chapter 4. Results reflect 3 percent and 7 percent discount rates consistent with EPA and OMB guidelines for preparing economic analyses (U.S. EPA, 2000; OMB, 2003). f Net benefits are rounded to the nearest $100 million. Columnar totals may not sum due to rounding. 

TABLE IV–4.—UNQUANTIFIED AND NONMONETIZED EFFECTS OF THE CLEAN AIR VISIBILITY RULE

Pollutant/effect Effects not included in primary estimates—changes in: 

Ozone—Health a .................................................. • Premature mortality b. 

• Chronic respiratory damage. 

• Premature aging of the lungs. 

• Nonasthma respiratory emergency room visits. 

• Increased exposure to Uvb. 

• Hospital Admissions : respiratory. 

• Emergency room visits for asthma. 

• Minor restricted activity days. 

• School loss days. 

• Asthma attacks. 

• Cardiovascular emergency room visits. 

• Acute respiratory symptoms. 

Ozone—Welfare .................................................. • Yields for: 

—Commercial forests, 

—Fruits and vegetables, and 

—Commercial and noncommercial crops. 

• Damage to urban ornamental plants. 

• Recreational demand from damaged forest aesthetics. 

• Ecosystem functions. 

• Increased exposure to UVb. 

PM—Health c. ...................................................... • Premature mortality: short-term exposuresd. 

• Low birth weight. 

• Pulmonary function. 

• Chronic respiratory diseases other than chronic bronchitis. 

• Nonasthma respiratory emergency room visits. 

• Exposure to UVb (+/¥) e. 

PM—Welfare ....................................................... • Visibility in many Class I areas. 

• Residential and recreational visibility in non-Class I areas. 

• Soiling and materials damage. 

• Ecosystem functions. 

• Exposure to UVb (+/¥)e. 

Nitrogen and Sulfate Deposition—Welfare ......... • Commercial forests due to acidic sulfate and nitrate deposition. 

• Commercial freshwater fishing due to acidic deposition. 

• Recreation in terrestrial ecosystems due to acidic deposition. 

• Existence values for currently healthy ecosystems. 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39149

TABLE IV–4.—UNQUANTIFIED AND NONMONETIZED EFFECTS OF THE CLEAN AIR VISIBILITY RULE—Continued

Pollutant/effect Effects not included in primary estimates—changes in: 

• Commercial fishing, agriculture, and forests due to nitrogen deposition. 

• Recreation in estuarine ecosystems due to nitrogen deposition. 

• Ecosystem functions. 

• Passive fertilization due to nitrogen deposition. 

Mercury Health g .................................................. • Incidence of neurological disorders. 

• Incidence of learning disabilities. 

• Incidence of developmental delays. 

• Potential reproductive effectsf. 

• Potential cardiovascular effectsf, including: 

—Altered blood pressure regulation f

—Increased heart rate variability f

—Incidence of myocardial infarction f

Mercury Deposition Welfare g .............................. • Impacts on birds and mammals (e.g., reproductive effects). 

• Impacts to commercial, subsistence, and recreational fishing. 

a In addition to primary economic endpoints, there are a number of biological responses that have been associated with ozone health effects 

including increased airway responsiveness to stimuli, inflammation in the lung, acute inflammation and respiratory cell damage, and increased 

susceptibility to respiratory infection. The public health impact of these biological responses may be partly represented by our quantified 

endpoints. bPremature mortality associated with ozone is not currently included in the primary analysis. Recent evidence suggests that short-term exposures to ozone may have a significant effect on daily mortality rates, independent of exposure to PM. EPA is currently conducting a series of 

meta-analyses of the ozone mortality epidemiology literature. EPA will consider including ozone mortality in primary benefits analyses once a 

peer-reviewed methodology is available. c In addition to primary economic endpoints, there are a number of biological responses that have been associated with PM health effects including morphological changes and altered host defense mechanisms. The public health impact of these biological responses may be partly represented by our quantified endpoints. dWhile some of the effects of short term exposures are likely to be captured in the estimates, there may be premature mortality due to short 

term exposure to PM not captured in the cohort study upon which the primary analysis is based. e May result in benefits or disbenefits. See discussion in Section 5.3.4 for more details. 

fThese are potential effects as the literature is insufficient. 

g Mercury emission reductions are not anticipated for BART for the EGU source category due to the cap-and-trade program promulgated for 

the Clean Air Mercury Rule (March 2005); however, the geographic location of mercury reductions may change as a result of this rule. EPA believes any such effects for these sources would be minimal. Mercury reductions are expected for the non-EGU source categories. The mercury 

reduction for BART from the non-EGU source categories is expected to be small in comparison to reductions resulting from the recently promulgated Clean Air Interstate Rule and the Clean Air Mercury Rule (March 2005). 

3. How Do the Benefits Compare to the 

Costs of This Final Rule?

In estimating the net benefits of 

regulation, the appropriate cost measure 

is ‘‘social costs.’’ Social costs represent 

the welfare costs of the rule to society. 

The social costs of this rule for the EGU 

and non-EGU sector sources are 

estimated to range from approximately 

$0.3 to $2.9 billion in 2015. This range 

depends upon the control scenario 

assumed and applicable discount rates 

of 3 percent and 7 percent. The net 

benefits (social benefits minus social 

costs) of the rule range from 

approximately $1.9 + B billion or $12.0 

+ B billion depending upon the scenario 

evaluated and the applicable discount 

rate (3 and 7 percent) annually in 2015. 

Implementation of the rule is expected 

to provide society with a substantial net 

gain in social welfare based on 

economic efficiency criteria. 

There is uncertainty surrounding the 

actions States are likely to take to 

comply with the BART guidelines. 

States will determine BART-eligible 

sources based upon CAA criteria, 

determine those BART-eligible sources 

reasonably anticipated to cause or 

contribute to visibility impairment in 

Class I areas and then apply a 5 factor 

test for BART determinations. The range 

of estimated benefits, costs, and 

resulting net benefits for BART reflects 

the uncertainty concerning States 

responses to BART and represents 

EPA’s best estimates of the benefit-cost 

outcomes of alternative compliance 

scenarios. 

The annualized cost of BART, as 

quantified here, is EPA’s best 

assessment of the cost of actions States 

are likely to take to comply with the 

rule. The EGU portion of these costs are 

generated from rigorous economic 

modeling of changes in the power sector 

due to the BART rule and guidelines. 

This type of analysis using IPM has 

undergone peer review and been upheld 

in Federal courts. The direct cost 

includes, but is not limited to, capital 

investments in pollution controls, 

operating expenses of the pollution 

controls, investments in new generating 

sources, and additional fuel 

expenditures. The EPA believes that 

these costs reflect, as closely as possible, 

the additional costs of the BART rule 

and guidelines to industry. However, 

there may exist certain costs that EPA 

has not quantified in these estimates. 

These costs may include costs of 

transitioning to the BART, such as the 

costs associated with the retirement of 

smaller or less efficient EGUs, 

employment shifts as workers are 

retrained at the same company or reemployed elsewhere in the economy. 

Costs may be understated since an 

optimization model was employed that 

assumes cost minimization, and the 

regulated community may not react in 

the same manner to comply with the 

rule. Although EPA has not quantified 

these potential additional costs, the 

Agency believes that they are small 

compared to the quantified costs of the 

program on the power sector. The 

annualized cost estimates presented are 

the best and most accurate based upon 

available information. 

The non-EGU portion of these costs 

are generated from extensive cost 

modeling based on applying illustrative 

regulatory scenarios to the non-EGU 

source categories. These costs represent 

potential impacts to non-EGU sources 

from State-imposed BART requirements. 

The direct cost includes, but is not 

limited to, capital investments in 

pollution controls, operating and 

maintenance expenses of the pollution 

controls, and additional fuel 

expenditures. The EPA believes that 

these costs reflect, as closely as possible, 

the potential additional costs of the 

BART rule and guidelines to industries 

with non-EGU sources. However, there 

39150 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

87Mrozek, J.R. and L.O. Taylor, What determines 

the value of a life? A Meta Analysis, Journal of 

Policy Analysis and Management 21 (2), pp. 253–

270.

88U.S. EPA. (2004). Air Quality Criteria for 

Particulate Matter. Research Triangle Park, NC: 

National Center for Environmental Assessment-RTP 

Office; Report No. EPA/600/P–99/002aD.

may exist certain costs that EPA has not 

quantified in these estimates. These 

costs may include costs of transitioning 

to the BART rule and guidelines, such 

as the costs associated with the 

retirement of smaller or less efficient 

non-EGUs, employment shifts as 

workers are retrained at the same 

company or re-employed elsewhere in 

the economy, and costs associated with 

applying both SO2 and NOX controls at 

one facility at the same time. Costs may 

be understated since the non-EGU cost 

modeling presumed a least-cost 

approach, and the potentially regulated 

community may not react in the same 

manner to comply with the rules. 

Although EPA has not quantified these 

costs, the Agency believes that they are 

small compared to the quantified costs 

of the program on industries with 

potentially affected non-EGU sources. 

The annualized cost estimates presented 

are the best and most accurate based 

upon available information. In a 

separate analysis, EPA estimates the 

indirect costs and impacts of higher 

electricity prices and costs applicable to 

the non-EGU sectors on the entire 

economy [see Regulatory Impact 

Analysis for the Final Clean Visibility 

Rule, Appendix A (June 2005)].

The costs presented here are EPA’s 

best estimate of the direct private costs 

of the BART rule and guidelines. For 

purposes of benefit-cost analysis of this 

rule, EPA has also estimated the 

additional costs of BART using alternate 

discount rates for calculating the social 

costs, parallel to the range of discount 

rates used in the estimates of the 

benefits of BART (3 percent and 7 

percent). Using these alternate discount 

rates, the social costs of BART range 

from $0.3 to $2.9 billion in 2015. (Note 

the portion of these annual costs 

associated with non-EGU sources 

represents incremental private cost 

estimates that are used as a proxy for the 

social costs of the rule.) 

Every benefit-cost analysis examining 

the potential effects of a change in 

environmental protection requirements 

is limited to some extent by data gaps, 

limitations in model capabilities (such 

as geographic coverage), and 

uncertainties in the underlying 

scientific and economic studies used to 

configure the benefit and cost models. 

Gaps in the scientific literature often 

result in the inability to estimate 

quantitative changes in health and 

environmental effects. Gaps in the 

economics literature often result in the 

inability to assign economic values even 

to those health and environmental 

outcomes that can be quantified. While 

uncertainties in the underlying 

scientific and economics literatures 

(that may result in overestimation or 

underestimation of benefits) are 

discussed in detail in the economic 

analyses and its supporting documents 

and references, the key uncertainties 

which have a bearing on the results of 

the benefit-cost analysis of this rule 

include the following: 

• Uncertainty concerning actions 

States will undertake to comply with 

BART; 

• EPA’s inability to quantify 

potentially significant benefit categories; 

• Uncertainties in population growth 

and baseline incidence rates; 

• Uncertainties in projection of 

emissions inventories and air quality 

into the future; 

• Uncertainty in the estimated 

relationships of health and welfare 

effects to changes in pollutant 

concentrations including the shape of 

the C–R function, the size of the effect 

estimates, and the relative toxicity of the 

many components of the PM mixture; 

• Uncertainties in exposure 

estimation; and 

• Uncertainties associated with the 

effect of potential future actions to limit 

emissions. 

Despite these uncertainties, we 

believe the benefit-cost analysis 

provides a reasonable indication of the 

expected economic benefits of the 

rulemaking in future years under a set 

of reasonable assumptions. 

In valuing reductions in premature 

fatalities associated with PM, we used a 

value of $5.5 million per statistical life. 

This represents a central value 

consistent with a range of values from 

$1 to $10 million suggested by recent 

meta-analyses of the wage-risk value of 

statistical life (VSL) literature.87

The benefits estimates generated for 

this rule are subject to a number of 

assumptions and uncertainties, that are 

discussed throughout the Regulatory 

Impact Analysis document [Regulatory 

Impact Analysis for the Final Clean Air 

Visibility Rule (April 2005)]. As Table 

IV–2 indicates, total benefits are driven 

primarily by the reduction in premature 

fatalities each year. Elaborating on the 

previous uncertainty discussion, some 

key assumptions underlying the primary 

estimate for the premature mortality 

category include the following: 

(1) EPA assumes inhalation of fine 

particles is causally associated with 

premature death at concentrations near 

those experienced by most Americans 

on a daily basis. Plausible biological 

mechanisms for this effect have been 

hypothesized for the endpoints 

included in the primary analysis and 

the weight of the available 

epidemiological evidence supports an 

assumption of causality. 

(2) EPA assumes all fine particles, 

regardless of their chemical 

composition, are equally potent in 

causing premature mortality. This is an 

important assumption, because the 

proportion of certain components in the 

PM mixture produced via precursors 

emitted from EGUs may differ 

significantly from direct PM released 

from automotive engines and other 

industrial sources, but no clear 

scientific grounds exist for supporting 

differential effects estimates by particle 

type. 

(3) EPA assumes the C–R function for 

fine particles is approximately linear 

within the range of ambient 

concentrations under consideration. In 

the PM Criteria Document, EPA 

recognizes that for individuals and 

specific health responses there are likely 

threshold levels, but there remains little 

evidence of thresholds for PM-related 

effects in populations.88 Where 

potential threshold levels have been 

suggested, they are at fairly low levels 

with increasing uncertainty about 

effects at lower ends of the PM2.5

concentration ranges. Thus, EPA 

estimates include health benefits from 

reducing the fine particles in areas with 

varied concentrations of PM, including 

both regions that are in attainment with 

fine particle standard and those that do 

not meet the standard.

The EPA recognizes the difficulties, 

assumptions, and inherent uncertainties 

in the overall enterprise. The analyses 

upon which the BART rule and 

guidelines are based were selected from 

the peer-reviewed scientific literature. 

We used up-to-date assessment tools, 

and we believe the results are highly 

useful in assessing this rule. 

There are a number of health and 

environmental effects that we were 

unable to quantify or monetize. A 

complete benefit-cost analysis of BART 

requires consideration of all benefits 

and costs expected to result from the 

rule, not just those benefits and costs 

which could be expressed here in dollar 

terms. A listing of the benefit categories 

that were not quantified or monetized in 

our estimate are provided in Table IV–

4. These effects are denoted by ‘‘B’’ in 

Table IV–3 above, and are additive to 

the estimates of benefits. 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39151

4. What Are the Unquantified and 

Unmonetized Benefits of BART 

Emissions Reductions?

Important benefits beyond the human 

health and welfare benefits resulting 

from reductions in ambient levels of 

PM2.5 and ozone are expected to occur 

from this rule. These other benefits 

occur both directly from NOX and SO2

emissions reductions, and indirectly 

through reductions in co-pollutants 

such as mercury. These benefits are 

listed in Table IV–4. Some of the more 

important examples include: Reductions 

in NOX and SO2 emissions required by 

BART will reduce acidification and, in 

the case of NOX, eutrophication of water 

bodies. Reduced nitrate contamination 

of drinking water is another possible 

benefit of the rule. This final rule will 

also reduce acid and particulate 

deposition that cause damages to 

cultural monuments, as well as, soiling 

and other materials damage. 

To illustrate the important nature of 

benefit categories we are currently 

unable to monetize, we discuss two 

categories of public welfare and 

environmental impacts related to 

reductions in emissions required by 

BART: reduced acid deposition and 

reduced eutrophication of water bodies. 

a. What Are the Benefits of Reduced 

Deposition of Sulfur and Nitrogen to 

Aquatic, Forest, and Coastal 

Ecosystems? 

Atmospheric deposition of sulfur and 

nitrogen, more commonly known as 

acid rain, occurs when emissions of SO2

and NOX react in the atmosphere (with 

water, oxygen, and oxidants) to form 

various acidic compounds. These acidic 

compounds fall to earth in either a wet 

form (rain, snow, and fog) or a dry form 

(gases and particles). Prevailing winds 

can transport acidic compounds 

hundreds of miles, across State borders. 

Acidic compounds (including small 

particles such as sulfates and nitrates) 

cause many negative environmental 

effects, including acidification of lakes 

and streams, harm to sensitive forests, 

and harm to sensitive coastal 

ecosystems. 

i. Acid Deposition and Acidification of 

Lakes and Streams 

The extent of adverse effects of acid 

deposition on freshwater and forest 

ecosystems depends largely upon the 

ecosystem’s ability to neutralize the 

acid. The neutralizing ability [key 

indicator is termed Acid Neutralizing 

Capacity (ANC)] depends largely on the 

watershed’s physical characteristics: 

geology, soils, and size. Waters that are 

sensitive to acidification tend to be 

located in small watersheds that have 

few alkaline minerals and shallow soils. 

Conversely, watersheds that contain 

alkaline minerals, such as limestone, 

tend to have waters with a high ANC. 

Areas especially sensitive to 

acidification include portions of the 

Northeast (particularly, the Adirondack 

and Catskill Mountains, portions of New 

England, and streams in the midAppalachian highlands) and 

southeastern streams. 

ii. Acid Deposition and Forest 

Ecosystem Impacts 

Current understanding of the effects 

of acid deposition on forest ecosystems 

focuses on the effects of ecological 

processes affecting plant uptake, 

retention, and cycling of nutrients 

within forest ecosystems. Recent studies 

indicate that acid deposition is at least 

partially responsible for decreases in 

base cations (calcium, magnesium, 

potassium, and others) from soils in the 

northeastern and southeastern United 

States. Losses of calcium from forest 

soils and forested watersheds have now 

been documented as a sensitive early 

indicator of soil response to acid 

deposition for a wide range of forest 

soils in the United States. 

In red spruce stands, a clear link 

exists between acid deposition, calcium 

supply, and sensitivity to abiotic stress. 

Red spruce uptake and retention of 

calcium is impacted by acid deposition 

in two main ways: leaching of important 

stores of calcium from needles and 

decreased root uptake of calcium due to 

calcium depletion from the soil and 

aluminum mobilization. These changes 

increase the sensitivity of red spruce to 

winter injuries under normal winter 

conditions in the Northeast, result in the 

loss of needles, slow tree growth, and 

impair the overall health and 

productivity of forest ecosystems in 

many areas of the eastern United States. 

In addition, recent studies of sugar 

maple decline in the Northeast 

demonstrate a link between low base 

cation availability, high levels of 

aluminum and manganese in the soil, 

and increased levels of tree mortality 

due to native defoliating insects. 

Although sulfate is the primary cause 

of base cation leaching, nitrate is a 

significant contributor in watersheds 

that are nearly nitrogen saturated. Base 

cation depletion is a cause for concern 

because of the role these ions play in 

surface water acid neutralization and 

their importance as essential nutrients 

for tree growth (calcium, magnesium 

and potassium). 

This regulatory action will decrease 

acid deposition in the transport region 

and is likely to have positive effects on 

the health and productivity of forest 

systems in the region. 

iii. Coastal Ecosystems 

Since 1990, a large amount of research 

has been conducted on the impact of 

nitrogen deposition to coastal waters. 

Nitrogen is often the limiting nutrient in 

coastal ecosystems. Increasing the levels 

of nitrogen in coastal waters can cause 

significant changes to those ecosystems. 

In recent decades, human activities have 

accelerated nitrogen nutrient inputs, 

causing excessive growth of algae and 

leading to degraded water quality and 

associated impairments of estuarine and 

coastal resources. 

Atmospheric deposition of nitrogen is 

a significant source of nitrogen to many 

estuaries. The amount of nitrogen 

entering estuaries due to atmospheric 

deposition varies widely, depending on 

the size and location of the estuarine 

watershed and other sources of nitrogen 

in the watershed. There are a few 

estuaries where atmospheric deposition 

of nitrogen contributes well over 40 

percent of the total nitrogen load; 

however, in most estuaries for which 

estimates exist, the contribution from 

atmospheric deposition ranges from 15–

30 percent. The area of the country with 

the highest air deposition rates (30 

percent deposition rates) includes many 

estuaries along the northeast seaboard 

from Massachusetts to the Chesapeake 

Bay and along the central Gulf of 

Mexico coast.

In 1999, National Oceanic and 

Atmospheric Administration (NOAA) 

published the results of a 5-year 

national assessment of the severity and 

extent of estuarine eutrophication. An 

estuary is defined as the inland arm of 

the sea that meets the mouth of a river. 

The 138 estuaries characterized in the 

study represent more than 90 percent of 

total estuarine water surface area and 

the total number of U.S. estuaries. The 

study found that estuaries with 

moderate to high eutrophication 

represented 65 percent of the estuarine 

surface area. 

Eutrophication is of particular 

concern in coastal areas with poor or 

stratified circulation patterns, such as 

the Chesapeake Bay, Long Island Sound, 

and the Gulf of Mexico. In such areas, 

the ‘‘overproduced’’ algae tends to sink 

to the bottom and decay, using all or 

most of the available oxygen and 

thereby reducing or eliminating 

populations of bottom-feeder fish and 

shellfish, distorting the normal 

population balance between different 

aquatic organisms, and in extreme cases, 

causing dramatic fish kills. Severe and 

persistent eutrophication often directly 

impacts human activities. For example, 

39152 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

fishery resource losses can be caused 

directly by fish kills associated with low 

dissolved oxygen and toxic blooms. 

Declines in tourism occur when low 

dissolved oxygen causes Noxious smells 

and floating mats of algal blooms create 

unfavorable aesthetic conditions. Risks 

to human health increase when the 

toxins from algal blooms accumulate in 

edible fish and shellfish, and when 

toxins become airborne, causing 

respiratory problems due to inhalation. 

According to the NOAA report, more 

than half of the nation’s estuaries have 

moderate to high expressions of at least 

one of these symptoms’an indication 

that eutrophication is well developed in 

more than half of U.S. estuaries. 

This rule is anticipated to reduce 

nitrogen deposition in the nation. Thus, 

reductions in the levels of nitrogen 

deposition will have a positive impact 

upon current eutrophic conditions in 

estuaries and coastal areas in the 

country. 

5. Are There Health or Welfare 

Disbenefits of the BART That Have Not 

Been Quantified? 

In contrast to the additional benefits 

of the rule discussed above, it is also 

possible that this rule will result in 

disbenefits in some areas of the region. 

Current levels of nitrogen deposition in 

these areas may provide passive 

fertilization for forest and terrestrial 

ecosystems where nutrients are a 

limiting factor and for some croplands. 

The effects of ozone and PM on 

radiative transfer in the atmosphere can 

also lead to effects of uncertain 

magnitude and direction on the 

penetration of ultraviolet light and 

climate. Ground level ozone makes up 

a small percentage of total atmospheric 

ozone (including the stratospheric layer) 

that attenuates penetration of 

ultraviolet—b (UVb) radiation to the 

ground. The EPA’s past evaluation of 

the information indicates that potential 

disbenefits would be small, variable, 

and with too many uncertainties to 

attempt quantification of relatively 

small changes in average ozone levels 

over the course of a year (EPA, 2005a). 

The EPA’s most recent provisional 

assessment of the currently available 

information indicates that potential but 

unquantifiable benefits may also arise 

from ozone-related attenuation of UVb 

radiation (EPA, 2005b). Sulfate and 

nitrate particles also scatter UVb, which 

can decrease exposure of horizontal 

surfaces to UVb, but increase exposure 

of vertical surfaces. In this case as well, 

both the magnitude and direction of the 

effect of reductions in sulfate and nitrate 

particles are too uncertain to quantify 

(EPA, 2004). Ozone is a greenhouse gas, 

and sulfates and nitrates can reduce the 

amount of solar radiation reaching the 

earth, but EPA believes that we are 

unable to quantify any net climaterelated disbenefit or benefit associated 

with the combined ozone and PM 

reductions in this rule. 

B. Paperwork Reduction Act 

Today’s rule clarifies, but does not 

modify the information collection 

requirements for BART. Therefore, this 

action does not impose any new 

information collection burden. 

However, the OMB has previously 

approved the information collection 

requirements contained in the existing 

regulations [40 CFR Part 51] under the 

provisions of the Paperwork Reduction 

Act, 44 U.S.C. 3501 et seq. and has 

assigned OMB control number 2060–

0421, EPA ICR number 1813.04. A copy 

of the OMB approved Information 

Collection Request (ICR) may be 

obtained from Susan Auby, Collection 

Strategies Division; U.S. Environmental 

Protection Agency (2822T); 1200 

Pennsylvania Ave., NW, Washington, 

DC 20460 or by calling (202) 566–1672. 

Burden means the total time, effort, or 

financial resources expended by persons 

to generate, maintain, retain, or disclose 

or provide information to or for a 

Federal agency. This includes the time 

needed to review instructions; develop, 

acquire, install, and utilize technology 

and systems for the purposes of 

collecting, validating, and verifying 

information, processing and 

maintaining information, and disclosing 

and providing information; adjust the 

existing ways to comply with any 

previously applicable instructions and 

requirements; train personnel to be able 

to respond to a collection of 

information; search data sources; 

complete and review the collection of 

information; and transmit or otherwise 

disclose the information. 

An agency may not conduct or 

sponsor, and a person is not required to 

respond to a collection of information 

unless it displays a currently valid OMB 

control number. The OMB control 

numbers for EPA’s regulations in 40 

CFR are listed in 40 CFR part 9.

C. Regulatory Flexibility Act 

EPA has determined that it is not 

necessary to prepare a regulatory 

flexibility analysis in connection with 

this final rule. 

For purposes of assessing the impacts 

of today’s rule on small entities, small 

entity is defined as: (1) A small business 

as defined by the Small Business 

Administrations’ regulations at 13 CFR 

121.201; (2) a small governmental 

jurisdiction that is a government of a 

city, county, town, school district or 

special district with a population of less 

than 50,000; and (3) a small 

organization that is any not-for-profit 

enterprise which is independently 

owned and operated and is not 

dominant in its field. 

Table IV–5 lists potentially impacted 

BART industry source categories and 

the current applicable small business 

criteria established by the Small 

Business Administration.

TABLE IV–5. POTENTIALLY AFFECTED BART SOURCE CATEGORIES AND SMALL BUSINESS SIZE STANDARDS

NAICSa Description Size standard b

221112 c,d ..................... Fossil fuel-fired electric utility steam generating units ........................................................... electric output ≤ 4 million 

megawatt hours. 

212112 ......................... Bituminous Coal Underground Mining ................................................................................... 500 Employees. 

311221 ......................... Wet Corn Milling ..................................................................................................................... 750 Employees. 

311311 ......................... Sugarcane Mills ...................................................................................................................... 500 Employees. 

311313 ......................... Beet Sugar Manufacturing ..................................................................................................... 750 Employees. 

31214 ........................... Distilleries ............................................................................................................................... 750 Employees. 

321212 ......................... Softwood Veneer and Plywood Manufacturing ...................................................................... 500 Employees. 

322121 ......................... Paper (except Newsprint) Mills (pt) ....................................................................................... 750 Employees. 

325188 ......................... All Other Basic Inorganic Chemical Manufacturing (pt) ........................................................ 1,000 Employees. 

325221 ......................... Cellulosic Organic Fiber Manufacturing ................................................................................. 1,000 Employees. 

325222 ......................... Noncellulosic Organic Fiber Manufacturing ........................................................................... 1,000 Employees. 

325182 ......................... Carbon Black Manufacturing (pt) ........................................................................................... 500 Employees. 

327213 ......................... Glass Container Manufacturing ............................................................................................. 750 Employees. 

327212 ......................... Other Pressed and Blown Glass and Glassware Manufacturing .......................................... 750 Employees. 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39153

89An ORIS code is a 4 digit number assigned by 

the Energy Information Administration (EIA) at the 

U.S. Department of Energy to power plants owned 

by utilities.

TABLE IV–5. POTENTIALLY AFFECTED BART SOURCE CATEGORIES AND SMALL BUSINESS SIZE STANDARDS—Continued

NAICSa Description Size standard b

32731 ........................... Cement Manufacturing ........................................................................................................... 750 Employees. 

32741 ........................... Lime Manufacturing ................................................................................................................ 500 Employees. 

331111 ......................... Iron and Steel Mills ................................................................................................................ 1,000 Employees. 

331315 ......................... Aluminum Sheet, Plate, and Foil Manufacturing ................................................................... 750 Employees. 

331319 ......................... Other Aluminum Rolling and Drawing ................................................................................... 750 Employees. 

22121 ........................... Natural Gas Distribution ......................................................................................................... 500 Employees. 

a North American Industry Classification System. 

bSmall Business Administration Size Criteria. 

c Include NAICS categories for source categories that own and operate electric generating units only. 

dFederal, State, or local government-owned and operated establishments are classified according to the activity in which they are engaged. 

After considering the economic 

impacts of today’s final rule on small 

entities, EPA has concluded that this 

action will not have a significant 

economic impact on a substantial 

number of small entities. This final rule 

will not impose any direct requirements 

on small entities. The rule would apply 

to States, not to small entities. 

Courts have interpreted the RFA to 

require a regulatory flexibility analysis 

only when small entities will be subject 

to the requirements of the rule. See 

Motor and Equip. Mfrs. Ass’n v. Nichols,

142 F. 3d 449 (D.C. Cir., 1998); United 

Distribution Cos. v. FERC, 88 F. 3d 

1105, 1170 (D.C. Cir., 1996); Mid-Tex 

Elec. Co-op, Inc. v. FERC, 773 F . 2d 

327, 342 (D.C. Cir., 1985) (agency’s 

certification need only consider the 

rule’s impact on entities subject to the 

rule). 

BART requirements in the regional 

haze rule require BART determinations 

for a select list of major stationary 

sources defined by section 169A(g)(7) of 

the CAA. However, as noted in the 

proposed and final regional haze rules, 

the State’s determination of BART for 

regional haze involves some State 

discretion in considering a number of 

factors set forth in section 169A(g)(2), 

including the costs of compliance. 

Further, the final regional haze rule 

allows States to adopt alternative 

measures in lieu of requiring the 

installation and operation of BART at 

these major stationary sources. As a 

result, the potential consequences of the 

BART provisions of the regional haze 

rule (as clarified in today’s rule) at 

specific sources are speculative. Any 

requirements for BART will be 

established by State rulemakings. The 

States would accordingly exercise 

substantial intervening discretion in 

implementing the BART requirements 

of the regional haze rule and today’s 

guidelines.

EPA has undertaken an illustrative 

analysis to assess the potential small 

business impacts of BART based upon 

EPA’s assessment of the actions States 

may take to comply with the BART rule 

and guidelines. 

For this final rule, the engineering 

analysis conducted for the rulemaking 

identified 491 EGU units potentially 

affected by the outcome of this rule. 

Using unit ORIS 89 numbers and the 

Energy Information Administration’s 

publicly available 2002 electric 

generator databases (Form EIA 860 and 

Form EIA 861), we identified utility 

names, nameplate capacity for affected 

units, and net electricity generation 

potentially affected by this rule. After 

identifying these units, we excluded 

units that are located in CAIR regions in 

order to identify those units most likely 

affected by the BART regulatory 

program. After an assessment of the 

ownership of these remaining units, we 

identified 2 potentially affected small 

entities in the EGU sector. We used a 

cost-to-sales approach (comparison of 

expected annual costs of emission 

controls to annual sales revenue or 

government entity budgets for the 

affected small entity) to assess the 

potential impacts of BART for these 

affected entities. Using data from the 

cost analysis, EPA found one of these 

small entities may experience a cost-tosales ratio of 3 percent of sales. The 

other affected small entity in the EGU 

sector does not face additional 

compliance costs associated with the 

rule.

The engineering analysis conducted 

for the rulemaking identified over 2,000 

records associated with affected nonEGU units (all source categories listed in 

table IV–5 other than EGUs—NAICS 

221112) potentially affected by the rule. 

Using publicly available sales and 

employment databases, plant names, 

and locations, we identified 279 entities 

and potential owners. In order to 

classify affected ultimate entities as 

small or large, EPA collected 

information on facility names, parent 

company sales, and parent company 

employment data. Data were compared 

with the appropriate size standard and 

entities were classified as small or large 

according to Small Business 

Administration’s definitions. For 

example, ultimate parent companies of 

cement producers with employment 

exceeding 750 employees were 

classified as large companies. This 

process identified 36 small companies 

and 195 large companies potentially 

impacted as a result promulgating this 

rule. The remaining 48 entities were 

either government-owned (25 entities, 

primarily state universities) or parent 

ownership could not be definitively 

identified using available databases (23 

entities). 

Using the cost-to-sales approach 

described above, EPA found that five 

non-EGU source category small entities 

may potentially be affected at or above 

3 percent. Two entities may be affected 

between one and three percent, and the 

remaining small entity cost-to-sales 

ratios are below one percent. The 

median cost-to-sales ratio for non-EGU 

source category small entities is 

estimated to be 0.3 percent and could 

potentially range from 0 to 20 percent. 

As previously discussed this analysis is 

illustrative and based upon EPA’s 

assessment of actions States are likely to 

take as a result of the BART rule and 

guidelines promulgated today. 

D. Unfunded Mandates Reform Act 

Title II of the Unfunded Mandates 

Reform Act of 1995 (Public Law 104–4) 

establishes requirements for Federal 

agencies to assess the effects of their 

regulatory actions on State, local, and 

Tribal governments and the private 

sector. Under section 202 of UMRA, 2 

U.S.C. 1532, EPA generally must 

prepare a written statement, including a 

cost-benefit analysis, for any proposed 

or final rule that ‘‘includes any Federal 

mandate that may result in the 

expenditure by State, local, and tribal 

governments, in the aggregate, or by the 

private sector, of $100,000,000 or more 

* * * in any one year.’’ A ‘‘Federal 

39154 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

mandate’’ is defined under section 

421(6), 2 U.S.C. 658(6), to include a 

‘‘Federal intergovernmental mandate.’’

A ‘‘Federal intergovernmental 

mandate,’’ in turn, is defined to include 

a regulation that ‘‘would impose an 

enforceable duty upon State, local, or 

tribal governments,’’ section 

421(5)(A)(I), 2 U.S.C. 658(5)(A)(I). A 

‘‘Federal private sector mandate’’

includes a regulation that ‘‘would 

impose an enforceable duty upon the 

private sector,’’ with certain exceptions, 

section 421(7)(A), 2 U.S.C. 658(7)(A). 

Before promulgating an EPA rule for 

which a written statement is needed 

under section 202 of UMRA, section 

205, 2 U.S.C. 1535, of UMRA generally 

requires EPA to identify and consider a 

reasonable number of regulatory 

alternatives and adopt the least costly, 

most cost effective, or least burdensome 

alternative that achieves the objectives 

of the rule.The RIA prepared by EPA 

and placed in the docket for this 

rulemaking is consistent with the 

requirements of section 202 of the 

UMRA. Furthermore, EPA is not 

directly establishing any regulatory 

requirements that may significantly or 

uniquely affect small governments, 

including tribal governments. Thus, 

EPA is not obligated to develop under 

section 203 of the UMRA a small 

government agency plan. Further, EPA 

carried out consultations with the 

governmental entities affected by this 

rule in a manner consistent with the 

intergovernmental consultation 

provisions of section 204 of the UMRA. 

The EPA also believes that today’s 

rule meets the UMRA requirement in 

section 205 to select the least costly and 

burdensome alternative in light of the 

statutory mandate for BART. As 

explained above, we are promulgating 

the BART rule and guidelines following 

the D.C. Circuit’s remand of the BART 

provisions in the 1999 regional haze 

rule. The 1999 regional haze rule 

provides substantial flexibility to the 

States, allowing them to adopt 

alternative measures such as a trading 

program in lieu of requiring the 

installation and operation of BART. The 

provisions governing such alternative 

measures were affected by a more recent 

decision of the D.C. Circuit and will be 

revised in a separate rulemaking 

process. Today’s rule will not restrict 

the ability of the States to adopt such 

alternatives measures once those 

revisions to the regional haze rule have 

been made final. This will provide an 

alternative to BART that gives States the 

ability to choose the least costly and 

least burdensome alternative. Today’s 

rule also allows States affected by the 

Clean Air Interstate Rule to utilize 

emission reductions achieved by EGUs 

under that rule to satisfy BART 

requirements for those sources. This 

will provide those States with another 

cost effective and less burdensome 

alternative to BART. 

The EPA is not reaching a final 

conclusion as to the applicability of 

UMRA to today’s rulemaking action. 

The reasons for this are discussed in the 

1999 regional haze rule (64 FR 35762) 

and in the 2001 BART guidelines 

proposal (66 FR 38111–38112). 

Notwithstanding this, the discussion in 

chapter 9 of the RIA constitutes the 

UMRA statement that would be required 

by UMRA if its statutory provisions 

applied. Consequently, we continue to 

believe that it is not necessary to reach 

a conclusion as to the applicability of 

the UMRA requirements.

E. Executive Order 13132: Federalism 

Executive Order 13132, entitled 

Federalism (64 FR 43255, August 10, 

1999), requires EPA to develop an 

accountable process to ensure 

‘‘meaningful and timely input by State 

and local officials in the development of 

regulatory policies that have federalism 

implications.’’ Such policies are defined 

in the Executive Order to include 

regulations that have ‘‘substantial direct 

effects on the States, on the relationship 

between the national government and 

the States, or on the distribution of 

power and responsibilities among the 

various levels of government.’’ Under 

section 6 of Executive Order 13132, EPA 

may not issue a regulation that has 

federalism implications, that imposes 

substantial direct compliance costs, and 

that is not required by statute, unless 

the Federal government provides the 

funds necessary to pay the direct 

compliance costs incurred by State and 

local governments, or EPA consults with 

State and local officials early in the 

process of developing the regulation. 

The EPA also may not issue a regulation 

that has federalism implications and 

that preempts State law unless EPA 

consults with State and local officials 

early in the process of developing the 

regulation. 

We have concluded that today’s 

action, promulgating the BART 

guidelines, will not have federalism 

implications, as specified in section 6 of 

the Executive Order 13132 (64 FR 

43255, August 10, 1999) because it will 

not have substantial direct effects on the 

States, nor substantially alter the 

relationship or the distribution of power 

and responsibilities between the States 

and the Federal government. 

Nonetheless, we consulted with a wide 

scope of State and local officials, 

including the National Governors 

Association, the National League of 

Cities, the National Conference of State 

Legislatures, the U. S. Conference of 

Mayors, the National Association of 

Counties, the Council of State 

Governments, the International City/

County Management Association, and 

the National Association of Towns and 

Townships during the course of 

developing this rule. 

F. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

Executive Order 13175, entitled 

‘‘Consultation and Coordination with 

Indian Tribal Governments’’ (65 FR 

67249, November 9, 2000), requires EPA 

to develop an accountable process to 

ensure ‘‘meaningful and timely input by 

Tribal officials in the development of 

regulatory policies that have Tribal 

implications.’’

This rule does not have Tribal 

implications as defined by Executive 

Order 13175. It does not have a 

substantial direct effect on one or more 

Indian Tribes. Furthermore, this rule 

does not affect the relationship or 

distribution of power and 

responsibilities between the Federal 

government and Indian Tribes. The 

CAA and the TAR establish the 

relationship of the Federal government 

and Tribes in developing plans to 

address air quality issues, and this rule 

does nothing to modify that 

relationship. This rule does not have 

Tribal implications, and Executive 

Order 13175 does not apply to this 

rulemaking. 

G. Executive Order 13045: Protection of 

Children From Environmental Health 

and Safety Risks 

Executive Order 13045, ‘‘Protection of 

Children from Environmental Health 

Risks and Safety Risks’’ (62 FR 19885, 

April 23, 1997) applies to any rule that 

(1) is determined to be ‘‘economically 

significant’’ as defined under Executive 

Order 12866 and (2) concerns an 

environmental health or safety risk that 

EPA has reason to believe may have a 

disproportionate effect on children. If 

the regulatory action meets both criteria, 

Section 5–501 of the Order directs the 

Agency to evaluate the environmental 

health or safety effects of the planned 

rule on children and to explain why the 

planned regulation is preferable to other 

potentially effective and reasonably 

feasible alternatives considered by the 

Agency. 

EPA interprets Executive Order 13045 

as applying only to those regulatory 

actions that are based on health and 

safety risks, such that the analysis 

required under section 5–501 of the 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39155

90U.S. Environmental Protection Agency, 1998. 

Guidance for Incorporating Environmental Justice 

Concerns in EPA’s NEPA Compliance Analyses. 

Office of Federal Activities, Washington, D.C., 

April, 1998.

Order has the potential to influence the 

regulation. The BART rule and 

guidelines are not subject to the 

Executive Order because the rule and 

guidelines do not involve decisions on 

environmental health or safety risks that 

may disproportionately affect children. 

The EPA believes that the emissions 

reductions from the control strategies 

considered in this rulemaking will 

further improve air quality and will 

further improve children’s health.

H. Executive Order 13211: Actions 

Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution, or Use 

We have conducted a Regulatory 

Impact Analysis for this rule, that 

includes an analysis of energy impacts 

and is contained in the docket (Docket 

No. OAR–2002–0076). This rule is not a 

‘‘significant energy action’’ as defined in 

Executive Order 13211, ‘‘Actions 

Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution, or Use’’ (66 FR 28355 (May 

22, 2001)) because it is not likely to 

have a significant adverse effect on the 

supply, distribution, or use of energy. 

This rule is not a ‘‘significant energy 

action,’’ because it will have less than 

a 1 percent impact on the cost of energy 

production and does not exceed other 

factors described by OMB that may 

indicate a significant adverse effect. 

(See, ‘‘Guidance for Implementing E.O. 

13211,’’ OMB Memorandum 01–27 (July 

13, 2001) http://www.whitehouse.gov/

omb/memoranda/m01–27.html.)

Specifically, the presumptive 

requirements for EGUs for this rule, 

when fully implemented, are expected 

have a 0.25 percent impact on the cost 

of energy production for the nation in 

2015. States must use the guidelines in 

making BART determinations for power 

plants with a generating capacity in 

excess of 750 MW. Our analysis 

evaluates the impact of the presumptive 

requirements for these sources and does 

not consider any possible additional 

controls for EGU sources or non-EGU 

sources that States may require. 

Although States may choose to use the 

guidelines in establishing BART limits 

for non-EGUs , ultimately States will 

determine the sources subject to BART 

and the appropriate level of control for 

such sources. 

We are finalizing today’s rule 

following the D.C. Circuit’s remand of 

the BART provisions in the 1999 

regional haze rule. The 1999 regional 

haze rule provides substantial flexibility 

to the States, allowing them to adopt 

alternative measures such as a trading 

program in lieu of requiring the 

installation and operation of BART. The 

provisions governing such alternative 

measures were affected by a more recent 

decision of the D.C. Circuit and will be 

revised in a separate rulemaking 

process. This rulemaking will not 

restrict the ability of the States to adopt 

alternative measures once those 

revisions to the regional haze rule have 

been made final. This will provide an 

alternative to BART that reduces the 

overall cost of the regulation and its 

impact on the energy supply. Today’s 

rule also allows States affected by the 

Clean Air Interstate Rule to utilize 

emission reductions achieved by EGUs 

under that rule to satisfy BART 

requirements for those sources. This 

will provide those States with another 

cost effective and less burdensome 

alternative to BART. The BART rule 

itself offers flexibility by offering the 

choice of meeting SO2 requirements 

between an emission rate and a removal 

rate. 

For a State that chooses to require 

case-by-case BART, today’s rule would 

establish presumptive levels of controls 

for SO2 and NOX for certain EGUs that 

the State finds are subject to BART. 

Based on its consideration of various 

factors set forth in the regulations; 

however, a State may conclude that a 

different level of control is appropriate. 

The States will accordingly exercise 

substantial intervening discretion in 

implementing the final rule. 

Additionally, we have assessed that the 

compliance dates for the rule will 

provide adequate time for EGUs to 

install the required emission controls. 

I. National Technology Transfer and 

Advancement Act 

Section 12(d) of the National 

Technology Transfer Advancement Act 

of 1995 (NTTAA), Public Law 104–113, 

section 12(d)(15 U.S.C. 272 note) directs 

EPA to use voluntary consensus 

standards (VCS) in its regulatory 

activities unless to do so would be 

inconsistent with applicable law or 

otherwise impractical. Voluntary 

consensus standards are technical 

standards (e.g., materials specifications, 

test methods, sampling procedures, and 

business practices) that are developed or 

adopted by VCS bodies. The NTTAA 

directs EPA to provide Congress, 

through OMB, explanations when the 

EPA decides not to use VCS.

This action does not involve technical 

standards; thus, EPA did not consider 

the use of any VCS. 

J. Executive Order 12898: Federal 

Actions To Address Environmental 

Justice in Minority Populations and 

Low-Income Populations 

Executive Order 12898, ‘‘Federal 

Actions to Address Environmental 

Justice in Minority Populations and 

Low-Income Populations,’’ requires 

federal agencies to consider the impact 

of programs, policies, and activities on 

minority populations and low-income 

populations. According to EPA 

guidance,90 agencies are to assess 

whether minority or low-income 

populations face risks or a rate of 

exposure to hazards that are significant 

and that ‘‘appreciably exceed or is likely 

to appreciably exceed the risk or rate to 

the general population or to the 

appropriate comparison group.’’ (EPA, 

1998)

In accordance with Executive Order 

12898, the Agency has considered 

whether this rule may have 

disproportionate negative impacts on 

minority or low income populations. 

Negative impacts to these subpopulations that appreciably exceed 

similar impacts to the general 

population are not expected because the 

Agency expects this rule to lead to 

reductions in air pollution emissions 

and exposures generally. 

K. Congressional Review Act 

The Congressional Review Act, 5 

U.S.C. 801 et seq., as added by the Small 

Business Regulatory Enforcement 

Fairness Act of 1996, generally provides 

that before a rule may take effect, the 

agency promulgating the rule must 

submit a rule report, which includes a 

copy of the rule, to each House of the 

Congress and to the Comptroller General 

of the United States. The EPA will 

submit a report containing this rule and 

other required information to the U.S. 

Senate, the U.S. House of 

Representatives, and the Comptroller 

General of the United States prior to 

publication of the rule in the Federal 

Register. A major rule cannot take effect 

until 60 days after it is published in the 

Federal Register. This action is a ‘‘major 

rule’’ as defined by 5 U.S.C. 804(2).

List of Subjects in 40 CFR Part 51 

Environmental protection, Air 

pollution control, Administrative 

practice and procedure, 

Intergovernmental relations, Lead, 

Nitrogen dioxide, Ozone, Particulate 

matter, Reporting and recordkeeping 

39156 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

requirements, Sulfur oxides, Volatile 

organic compounds.

Dated: June 15, 2005. 

Stephen L. Johnson, 

Administrator.

■ For the reasons set forth in the 

preamble, part 51 of chapter I of title 40 

of the Code of Federal Regulations is 

amended as follows:

PART 51—REQUIREMENTS FOR 

PREPARATION, ADOPTION, AND 

SUBMITTAL OF IMPLEMENTATION 

PLANS

■ 1. The authority citation for part 51 

continues to read as follows:

Authority: 23 U.S.C. 101; 42 U.S.C. 7410–

7671q.

■ 2. Section 51.302 is amended by 

revising paragraph (c)(4)(iii) to read as 

follows:

§ 51.302 Implementation control strategies 

for reasonably attributable visibility 

impairment.

* * * * *

(c) * * * 

(4) * * * 

(iii) BART must be determined for 

fossil-fuel fired generating plants having 

a total generating capacity in excess of 

750 megawatts pursuant to ‘‘Guidelines 

for Determining Best Available Retrofit 

Technology for Coal-fired Power Plants 

and Other Existing Stationary Facilities’’

(1980), which is incorporated by 

reference, exclusive of appendix E to the 

Guidelines, except that options more 

stringent than NSPS must be 

considered. Establishing a BART 

emission limitation equivalent to the 

NSPS level of control is not a sufficient 

basis to avoid the analysis of control 

options required by the guidelines. This 

document is EPA publication No. 450/

3–80–009b and has been approved for 

incorporation by reference by the 

Director of the Federal Register in 

accordance with 5 U.S.C. 552(a) and 1 

CFR part 51. It is for sale from the U.S. 

Department of Commerce, National 

Technical Information Service, 5285 

Port Royal Road, Springfield, Virginia 

22161. It is also available for inspection 

from the National Archives and Records 

Administration (NARA). For 

information on the availability of this 

material at NARA, call 202–741–6030, 

or go to: http://www.archives.gov/

federal_register/index.html.

* * * * *

■ 3. Section 51.308 is amended by 

revising paragraph (b), removing and 

reserving paragraph (c), revising 

paragraphs (e)(1)(ii), (e)(3), and (e)(4), 

and adding paragaphs (e)(5) and (6) to 

read as follows:

§ 51.308 Regional haze program 

requirements.

* * * * *

(b) When are the first implementation 

plans due under the regional haze 

program? Except as provided in 

§ 51.309(c), each State identified in 

§ 51.300(b)(3) must submit, for the 

entire State, an implementation plan for 

regional haze meeting the requirements 

of paragraphs (d) and (e) of this section 

no later than December 17, 2007. 

(c) [Reserved]

* * * * *

(e) * * * 

(1) * * * 

(ii) A determination of BART for each 

BART-eligible source in the State that 

emits any air pollutant which may 

reasonably be anticipated to cause or 

contribute to any impairment of 

visibility in any mandatory Class I 

Federal area. All such sources are 

subject to BART. 

(A) The determination of BART must 

be based on an analysis of the best 

system of continuous emission control 

technology available and associated 

emission reductions achievable for each 

BART-eligible source that is subject to 

BART within the State. In this analysis, 

the State must take into consideration 

the technology available, the costs of 

compliance, the energy and nonair 

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 improvement in visibility 

which may reasonably be anticipated to 

result from the use of such technology. 

(B) The determination of BART for 

fossil-fuel fired power plants having a 

total generating capacity greater than 

750 megawatts must be made pursuant 

to the guidelines in appendix Y of this 

part (Guidelines for BART 

Determinations Under the Regional 

Haze Rule).

(C) Exception. A State is not required 

to make a determination of BART for 

SO2 or for NOX if a BART-eligible 

source has the potential to emit less 

than 40 tons per year of such 

pollutant(s), or for PM10 if a BARTeligible source emits less than 15 tons 

per year of such pollutant.

* * * * *

(3) A State which opts under 40 CFR 

51.308(e)(2) to implement an emissions 

trading program or other alternative 

measure rather than to require sources 

subject to BART to install, operate, and 

maintain BART may satisfy the final 

step of the demonstration required by 

that section as follows: If the 

distribution of emissions is not 

substantially different than under 

BART, and the alternative measure 

results in greater emission reductions, 

then the alternative measure may be 

deemed to achieve greater reasonable 

progress. If the distribution of emissions 

is significantly different, the State must 

conduct dispersion modeling to 

determine differences in visibility 

between BART and the trading program 

for each impacted Class I area, for the 

worst and best 20 percent of days. The 

modeling would demonstrate ‘‘greater 

reasonable progress’’ if both of the 

following two criteria are met: 

(i) Visibility does not decline in any 

Class I area, and 

(ii) There is an overall improvement 

in visibility, determined by comparing 

the average differences between BART 

and the alternative over all affected 

Class I areas. 

(4) A State that opts to participate in 

the Clean Air Interstate Rule cap-andtrade and trade program under part 96 

AAA–EEE need not require affected 

BART-eligible EGU’s to install, operate, 

and maintain BART. A State that 

chooses this option may also include 

provisions for a geographic 

enhancement to the program to address 

the requirement under § 51.302(c) 

related to BART for reasonably 

attributable impairment from the 

pollutants covered by the CAIR cap-andtrade program. 

(5) After a State has met the 

requirements for BART or implemented 

emissions trading program or other 

alternative measure that achieves more 

reasonable progress than the installation 

and operation of BART, BART-eligible 

sources will be subject to the 

requirements of paragraph (d) of this 

section in the same manner as other 

sources. 

(6) Any BART-eligible facility subject 

to the requirement under paragraph (e) 

of this section to install, operate, and 

maintain BART may apply to the 

Administrator for an exemption from 

that requirement. An application for an 

exemption will be subject to the 

requirements of § 51.303(a)(2)–(h).

* * * * *

■ 4. Appendix Y to Part 51 is added to 

read as follows:

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? 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39157

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 BARTeligible 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 BARTeligible 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 caseby-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 

39158 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

emissions greater than 250 tons per year. 

Once the State has identified the BARTeligible 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 BARTeligible 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 BARTeligible 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, 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39159

(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 byproduct 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 onsite 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 

39160 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

1 Fine particles: Overview of Atmospheric 

Chemistry, Sources of Emissions, and Ambient 

Monitoring Data, Memorandum to Docket OAR 

2002–006, April 1, 2005.

2Note: 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.

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.

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 onefourth 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

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39161

3We 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 BARTeligible sources, you may use either 2-digit SICS or 

the equivalent in the NAICS system.

4Note: 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.

5We expect that regional planning organizations 

will have modeling information that identifies 

sources affecting visibility in individual class I 

areas.

The rule further defines ‘‘building, structure 

or facility’’ as:

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

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 BARTEligible 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 visibilityimpairing 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 

39162 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

6Note 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.

7The model code and its documentation are 

available at no cost for download from http://

www.epa.gov/scram001/tt22.htm#calpuff.

8The 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.

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.

location of a large number of BART-eligible 

sources within the State and in proximity to 

a Class I area justify this approach.6

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 EPAapproved 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.

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.

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 sourcereceptor 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). Upfront 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 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39163

10CALPUFF 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.

11That is, emission units that were in existence 

on August 7, 1977 and which began actual 

operation on or after August 7, 1962.

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.

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 BARTeligible 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 BARTeligible 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.

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 

39164 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

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.

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.

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 costeffective 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 Caseby-Case BART Analysis? 

The five steps are:

STEP 1—Identify All 12 Available Retrofit 

Control Technologies,

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, postcombustion 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.

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 ‘‘productionspecific’’ 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 loweremitting 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 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39165

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 

39166 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

14The 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.

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.

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39167

16Whenever 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).

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 costeffectiveness 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

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 costeffectiveness 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 costeffective 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 nonair 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.)

39168 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

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 ‘‘leastcost 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 costeffectiveness 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 


ER06JY05.000</GPH>
Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39169

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 mosteffective 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 longterm 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 

39170 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

17The model code and its documentation are 

available at no cost for download from http://

www.epa.gov/scram001/tt22.htm#calpuff.

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.

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:

• 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.

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). Upfront consultation will ensure that key 

technical issues are addressed before you 

conduct your modeling. 

• For each source, run the model, at precontrol 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 precontrol 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 precontrol 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 

Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 39171

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 postcombustion 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 oilfired 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 preexisting 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 yearround 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 postcombustion controls, you should likewise 

presume that these same levels are costeffective. 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.

39172 Federal Register / Vol. 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations 

19No Cell burners, dry-turbo-fired units, nor wetbottom tangential-fired units burning lignite were 

identified as BART-eligible, thus no presumptive 

limit was determined. Similarly, no wet-bottom 

tangential-fired units burning sub-bituminous were 

identified as BART-eligible.

20These limits reflect the design and 

technological assumptions discussed in the 

technical support document for NOX limits for 

these guidelines. 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.

21See 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. 22 70 FR 9705, February 28, 2005.

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 

MostEGUs can meet these presumptive 

NO X limits through the use of current 

combustion control technology, i.e. the 

careful control of combustion air and lowNOX 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

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.

[FR Doc. 05–12526 Filed 7–5–05; 8:45 am] 

BILLING CODE 6560–50–P