_PJ_ 

OAR Box 1790 

Prepped by Keeia Richards 

Document Number: 

216) ll-F-5 

Docket Number: 

A-90-37 

Printed 10/31/2008 12:43:16 PM Sheet 216 of 250 
P.2 

CT Ol* 

I SKI 

'<• PflO-*"0 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

Office of Air Quality Planning and Standards 

Research Triangle Park, North Carolina 27711 oy 

MEMORANDUM 

DATE: 

SUBJECT: 

FROM: 

October 23, 1992 

Proposed Rulemaking on Best Available Control 

Technology (BACTA //>- ,-. 

/ * -/JC'p 

David Solomon/^*--/^^^^^ / 

New Source Review Section (MD-15) 

TO: Air Docket A-91-3 0 

The attached revised draft proposed rulemaking on BACT was 

submitted for interagency review to the Office of Management and 

Budget in response to comments received from them, the Department 

of Energy, the Council of Economic Advisors and the Council on 

Competitiveness regarding EPA's original October 2, 1992 

rulemaking submittal. 

Attachment 

{r77&^M 

m 0^ \<$& 
P.3 

Iv 

• 

OCT-23-1992 05 = 01 FROM TO 89195415509 P. £'2 

October 22, 1992 

NOTE TO: Art Fraas 

FROM: Michael Shap iro^f 

Enclosed is a revised copy of the BACT rulemaking package, 

which incorporates the changes we have discussed and agreed upon. 

We have made one change to the agreed-upon changes in order 

to make a footnote better agree with the text: in footnote 11, 

"affordability analysis" was changed to "affordability 

considerations." 

Please call me if you have any questions regarding this 

rule. 
P.4 

6560-50 

ENVIRONMENTAL PROTECTION AGENCY 

40 CFR PARTS 51 AND 52 

[AD-FRL- ] 

REQUIREMENTS FOR PREPARATION, ADOPTION, 

AND SUBMITTAL OF IMPLEMENTATION PLANS; 

APPROVAL AND PROMULGATION OF 

IMPLEMENTATION PLANS 

AGENCY: Environmental Protection Agency (EPA) 

ACTION: Proposed Rule 

SUMMARY: To improve the effectiveness of the prevention of 

significant air quality deterioration program required by 

title I, part C, of the Clean Air Act (Act), EPA proposes 

today to amend its rules to clarify the regulatory 

definition of best available control technology (BACT) by 

adding language that elucidates the legal requirements for a 

BACT analysis. The new language specifies that a BACT 

analysis must contain the following two core requirements: 

1) the determination must consider a representative 

group of the range of available control systems for the 

source, and 

2) selection of a particular control system as BACT 

must be justified by a comparison of the candidate control 

systems in terms of the statutory criteria and supported by 

the record. 

In addition, EPA proposes to amend the regulations defining 

BACT to reflect the change made by § 403(d) of title IV of 
P.5 

2 

the Act Amendments of 1990 (1990 Amendments) to the 

statutory definition of BACT. 

The EPA is soliciting public comment on these proposed 

clarifications to the regulatory definition of BACT. 

DATES: Comments may be submitted to EPA at the address 

below on or before [60 days from date of publication]. A 

public hearing is scheduled for [ ]. The hearing may 

be canceled if no speakers have requested time to present 

their comments 15 days prior to the scheduled hearing date. 

Written comments in lieu of testimony are encouraged. 

DOCKET: Supporting information used in developing the 

proposed rule is contained in Docket No. A-91-30. This 

*, docket is available for public inspection and copying 

between 8:30 a.m. and 3:30 p.m., Monday through Friday, at 

the address listed below. A reasonable fee may be charged 

for copying. 

ADDRESSES: Comments must be mailed (in duplicate if 

possible) to: The EPA Air Docket (LE-131), Attn: Docket No, 

A-91-30, Room M-1500, Waterside Mall, 401 M Street SW, 

Washington, D.C. 20460. The public hearing will be 

held [ ]. 

FOR FURTHER INFORMATION CONTACT: The EPA's New Source 

Review Section at (919) 541-5591. Persons interested in 

attending the hearing or wishing to present oral testimony 

should contact Ms. JoAnn Allman, in writing, at the U.S. 

Environmental Protection Agency, Office of Air Quality 
P.6 

3 

Planning and Standards, Air Quality Management Division, 

Mail Drop 15, Research Triangle Park, North Carolina 27711. 

SUPPLEMENTARY INFORMATION 

I. Background 

Major stationary sources and major modifications are 

subject to the prevention of significant deterioration (PSD) 

review requirements of the Act (title I, part C). A subject 

facility may not be constructed without a permit that meets 

the requirements of § 165 of the Act. The current PSD 

program is implemented by two sets of regulations. The 

first set of regulations, 40 CFR 51.166, specifies the 

minimum requirements that a PSD air quality permit program 

under part C of the Act must contain in order to obtain 

approval by EPA as a revision to a State implementation plan 

(SIP). The second set, 40 CFR 52.21, delineates the Federal 

PSD permit program, which currently applies as part of the 

SIP for States that have not submitted a PSD program meeting 

the requirements of 40 CFR 51.166. Roughly two-thirds of 

the States are implementing their own PSD program which has 

been approved by EPA under 40 CFR 51.166. The regulations 

at 40 CFR 52.21 apply in the remaining States, most of which 

have been delegated the authority to implement the Federal 

PSD program. Among other substantive requirements, the 

facility must apply BACT pursuant to § 165(a)(4) [see also 
P.7 

4 

40 CFR 52.21(j) (Federal regulations), 40 CFR 51.166(j) 

(regulations setting forth the requirements for SIP approval 

of a State PSD program), and 40 CFR part 52, subpart A -

subpart FFF (various SIP requirements)].1 

Emissions limitations reflecting the application of the 

BACT requirement must be set forth in the PSD permit [see 

§ 165(a)(1)]. To obtain a PSD permit, an applicant must, 

among other requirements, conduct an analysis in accordance 

with EPA regulations to ensure the application of BACT to 

each new or modified emissions unit [see § 165(a)(2, 4)]. 

The required analysis must address "the degree of continuous 

emissions reduction which could be achieved by such 

facility" [see § 165(e)(3)(B) and 40 CFR 52.21(n)(1)(3)]. 

The term "best available control technology" is defined 

in the Act as: 

an emissions limitation based on the maximum 

degree of reduction of each pollutant subject to 

regulation under the Act emitted from or which 

results from any major emitting facility, which 

the permitting authority, on a case-by-case basis, 

taking into account energy, environmental, and 

economic impacts and other costs, determines is 

achievable for such facility through application 

of production processes and available methods, 

systems, and techniques, including fuel cleaning, 

clean fuels, or treatment or innovative fuel 

combustion techniques for control of each such 

pollutant. In no event shall application of "best 

available control technology" result in emissions 

of any pollutants which will exceed the emissions 

allowed by any applicable standard established 

pursuant to § 7411 or 7412 of this title. 

'Under the 1990 Amendments, in certain circumstances, BACT 

is also a requirement for obtaining a permit under Part D of the 

Act. 
P.8 

Emissions from any source utilizing clean fuels, 

or any other means, to comply with this paragraph 

shall not be allowed to increase above levels that 

would have been required under this paragraph as 

it existed prior to enactment of the Clean Air Act 

Amendments of 1990. 

[see § 169(3), as amended by § 403(d) of the 1990 

Amendments]. 

In determining BACT on a case-by-case basis, the 

reviewing authority evaluates the energy, environmental, and 

economic impacts and other costs associated with each of the 

candidate technologies considered in the analysis. The 

reviewing authority then specifies an emissions limitation, 

based on the maximum degree of reduction of each pollutant 

subject to regulation, taking into account energy, 

environmental, and economic impacts and other costs, it 

determines is achievable for such facility. In no event may 

a technology be selected that would not meet any applicable 

standard of performance under 40 CFR 60 [new source 

performance standards (NSPS)] or 61 [national emission 

standards for hazardous air pollutants (NESHAP)]. 

In addition, if the reviewing authority determines that 

there is no economically-reasonable or technologicallyfeasible way to accurately measure the emissions, and hence 

to impose an enforceable emissions standard, it may require 

the source to use design, alternative equipment, work 

practice or operational standards to reduce emissions of the 
P.9 

6 

pollutant to the maximum extent [40 CFR 52.21(b)(12); 40 CFR 

51.166(b)(12)].2 

In January 1979, EPA issued "Guidance for Determining 

BACT Under PSD," and in October 1990 issued a "PSD Workshop 

Manual" (EPA 450/2-80-081). These documents outlined an 

approach to the BACT analysis in which the applicant was to 

propose a base case as BACT, present more stringent control 

alternatives, and defend its BACT selection "demonstrating 

that each alternative control system... would cause 

unreasonable adverse energy, environmental, or economic 

impacts" (see "Guidance for Determining BACT Under PSD," 

January 4, 1979). The 1979 guidance document notes EPA's 

belief that Congress intended that the States have broad 

flexibility to decide on the relative weight to assign to 

each of these factors. Further, BACT was described as a 

"flexible approach [which] allows the permitting authority 

to consider a number of local factors (for example the size 

of the plant, the amount of air quality increment that would 

be consumed, and desired economic growth in the area) in 

deciding on a weighing scheme." This methodology in the 

2For example, if a coal storage pile emits coal dust to the 

atmosphere, it would make little sense to impose an emissions 

standard, since measuring the amount of coal dust rising off the 

pile may be nearly impossible. A much more direct approach to 

controlling emissions is, for example, requiring the owner to wet 

the coal pile periodically or to totally enclose it. This type 

of operational standard or work practice would be equivalent to 

an emissions limitation for the purpose of the BACT requirement. 

In some instances, it may be appropriate to express BACT for 

a particular pollutant as an emissions limitation and a work 

practice or operational standard. 
P.10 

7 

1979 guidance is commonly referred to as the "bottom-up" 

approach. 

In June 1986, EPA established a New Source Review (NSR) 

Task Force to address growing concerns about the 

effectiveness of the NSR programs in meeting the statutory 

requirements, and to recommend actions to improve EPA's 

exercise of its oversight and enforcement responsibilities 

in implementing the NSR program. Among the Task Force 

findings, based on a comprehensive review of numerous PSD 

permits issued during the previous several years, was that 

PSD applicants and States frequently were conducting 

inadequate BACT determinations. In numerous instances, 

applicants would propose an emissions limitation at or near 

an applicable NSPS under § 111 of the Act as the base case, 

and provide little or no consideration of more stringent 

control options before settling on the proposed level as 

BACT. States typically would accept these determinations 

with little or no independent analysis, thereby failing to 

fulfill their responsibilities under the Act. The Task 

Force pointed out two basic solutions to the problem of 

inadequate BACT analysis. One was to improve implementation 

of the existing method so that, in practice as well as in 

theory, the statutory requirements would be fulfilled. The 

other option was to call for an alternate approach to the 

BACT analyses in the expectation that its internal dynamics 

would achieve more effective implementation of the BACT 
P.11 

8 

requirements (see generally "New Source Review Task Force 

Report," Final Draft, December 1986). 

In the meantime, in an adjudicative decision on appeal 

of a PSD permit for a municipal waste combustor.(MWC), the 

Administrator held that a PSD applicant has the "burden of 

demonstrating that significant technical defects, or 

substantial local economic, energy, or environmental factors 

or other costs, warrant a control technology less efficient 

than [the most stringent technology available]" [see 

Honolulu Resource Recovery Facility ("H-Power"), PSD Appeal 

No. 86-8, at 7 (Remand Order, June 22, 1987)]. Shortly 

thereafter, EPA issued guidance calling for application of 

the H-Power holding to all BACT determinations for MWCs 

("Operational Guidance on Control Technology for New and 

Modified Municipal Waste Combustors," June 26, 1987). 

Subsequent to these events, EPA decided to promote what 

has come to be known as a "top-down" BACT method for all 

categories of PSD sources. In brief, the top-down procedure 

provides that available control technologies be ranked in 

descending order of control effectiveness. The PSD 

applicant first examines the most stringent alternative. 

That alternative is established as BACT unless the applicant 

demonstrates, and the permitting authority in its informed 

judgment agrees, that technical considerations, or energy, 

environmental, or economic impacts or other costs, justify a 

conclusion that this technology is not "achievable" or 
P.12 

9 

appropriate in this case as BACT. If a particular 

technology is deemed not to be BACT, then the next most 

stringent alternative is considered, and so on. 

In a December 1, 1987 memorandum, EPA Headquarters 

requested its Regional Offices to use a top-down method in 

their own BACT determinations, and to encourage State and 

local PSD permitting authorities to do so as well (see 

December 1, 1987 memorandum from Craig Potter, Assistant 

Administrator for Air and Radiation, entitled "Improving New 

Source Review"). The memorandum further directed Regional 

Offices to conduct timely reviews of PSD applications 

submitted to State permitting authorities, and to comment 

adversely on proposed PSD permits that failed to adequately 

consider control options more stringent than NSPS, as would 

be required as a matter of course in any acceptable method 

of determining BACT. If final State and local permits still 

failed to reflect adequate consideration of the relevant 

BACT factors, the Regions were to consider such permits 

deficient and consider appropriate enforcement action under 

§§ 113 and 167 (in the case of State-issued permits) or 

appeals to the Administrator under 40 CFR 124.19 (in the 

case of Federal permits) to remedy such deficiencies. 

In recommending the use of the top-down approach, EPA 

did not revise its existing PSD regulations, nor did it call 

for revision of applicable SIP's. Rather, in setting forth 

this policy approach, EPA relied upon the existing statutory 
P.13 

10 

and regulatory definitions for determining BACT. In so 

doing, it was EPA's view at that time that the top-down 

approach announced in decisions and memoranda constituted a 

reasonable method for implementing the existing provisions. 

The approach "represent[ed] EPA's judgment that existing 

BACT requirements can best be accomplished through a 

particular analytical methodology" [see letter from EPA 

Administrator William K. Reilly to American Paper Institute 

and the National Forest Products Association (collectively 

"API"), May 12, 1989]. In other words, EPA believed that 

utilization of the top-down approach would ensure that the 

two core criteria, as discussed below, would be adhered to 

by permitting authorities. 

On March 29, 1989 (supplemented on May 3 and 10, 1989), 

API petitioned EPA to rescind the top-down policy and 

initiate a rulemaking on BACT determinations. The EPA 

denied this request on May 12, 1989 (supplemented on June 

13, 1989), explaining that the top-down approach was not at 

variance with, nor a revision of, the PSD regulations, and 

that no rulemaking was required. Subsequently, API filed 

suit in the D.C. Circuit and in the U.S. District Court for 

D.C. API v. Reillv, D.C. Cir. No. 89-1428 (filed 7/10/89); 

API v. Reillv. D.C. Cir. No. 89-2030 (filed 7/18/89). A 

consortium of utilities also filed a petition for review of 

EPA's actions, [Alabama Power Co. v. EPA, D.C. Cir. No. 89-

1429 (filed 7/11/89) , and the case was consolidated with the 
P.14 

11 

API case]. The same consortium filed an administrative 

petition with EPA on February 1, 1990. Finally, API also 

challenged the 1990 EPA draft guidance document on top-down 

BACT, API V. Reillv, D.C. No. 90-1364 (filed 7/13/90). A 

settlement agreement has been entered into for these cases 

(see 56 FR 34202). The EPA has decided as a matter of 

policy to conduct this proposed rulemaking to facilitate 

greater public participation concerning these issues. 

II. Legal Requirements for a PSD Analysis 

In adopting the PSD program, Congress emphasized the 

importance of thorough and public analyses in PSD decision 

making, stating that one of the purposes of PSD is to assure 

that any decision to permit increased air pollution in any 

area to which PSD applies is made only after careful 

evaluation of all the consequences of such a decision and 

after adequate procedural opportunities for informed public 

participation in the decision making process [see § 160(5)]. 

As noted above, § 165 specifies, and EPA regulations 

reflect, the requirement to conduct, among other PSD permit 

review requirements, a BACT analysis. The statutory 

emphasis on procedural rigor is accompanied by expressions 

of congressional intent that States have wide discretion in 

setting final emissions limits reflecting BACT. States also 

have considerable discretion in other aspects of the PSD 

program, such as allocation of the available increment. For 
P.15 

12 

example, States could choose to allocate the increment on a 

first-come, first-served basis, preserve a portion of the 

increment to accommodate future growth, or allocate 

increment through a market-based approach. 

The legislative history on BACT makes it clear that 

Congress meant the State to make the final substantive 

decision on the appropriate level of technology for the 

source and area in question. The key passages of the Senate 

report show that the State has broad flexibility to exercise 

its judgment in implementing BACT. The report states: 

The decision regarding the actual 

implementation of best available control 

technology is a key one, and the committee places 

this responsibility with the State, to be 

determined in a case-by-case judgment. It is to 

be recognized that the phrase has broad 

flexibility in how it should and can be 

interpreted, depending on site. 

In making this key decision on the technology 

to be used, the State is to take into account 

energy, environmental, and economic impacts and 

other costs of the application of best available 

control technology. The weight assigned to such 

factors is to be determined by the State. Such a 

flexible approach allows the adoption of 

improvements in technology to become widespread 

far more rapidly than would occur with a uniform 

Federal standard (emphasis added). 

[see S.R. 95-217, 95th Cong., 1st Sess. 31 (1977)]. 

The Senate report language suggests two important bounds on 

the exercise of the discretion afforded to the permitting 

authority in determining BACT. First, it is clear that in 

adopting BACT, Congress intended PSD permitting authorities 

to exercise informed discretion to weigh energy, 
P.16 

**-3 

environmental, and economic impacts in determining BACT for 

a particular source, while leaving to the States the 

flexibility to decide on the relative weights to assign each 

of these factors in deciding among options.3 Second, it is 

also clear that Congress believed that one of the advantages 

of State flexibility would be to speed up the adoption of 

advances in control technology.4 

The exercise of discretion within these bounds can be 

fulfilled by more than one method of determining BACT. 

Regardless of the specific methodology used for determining 

3"The decision regarding the actual implementation of BACT 

is a key one, and the committee places this responsibility with 

the State, to be determined in a case-by-case judgment. It is 

recognized that the phrase has broad flexibility in how it should 

and can be interpreted, depending on site. 

In making this key decision on the technology to be used, 

the State is to take into account energy, environmental, and 

economic impacts and other costs of the application of BACT. The 

weight assigned to such factors is to be determined by the State. 

Such a flexible approach allows the adoption of improvements in 

technology to become widespread far more rapidly than would occur 

with a uniform Federal standard. The only Federal guidelines are 

the EPA new source performance and hazardous emissions standards, 

which represent a floor for the State's decision. 

This directive enables the State to consider the size of the 

plant, the increment of air quality which will be absorbed by any 

particular major emitting facility, and such other considerations 

as anticipated and desired economic growth for the area. This 

allows the States and local communities to judge how much of the 

defined increment of significant deterioration will be devoted to 

any manor emitting facility. If, under the design which a major 

facility propose, the percentage of the increment would 

effectively prevent growth after the proposed major facility was 

completed, the State or community could refuse to permit 

construction, or limit its size. This is strictly a State and 

local decision" (emphasis added) [see Sen. Rep. No. 95-217, 95th 

Cong., 1st Sess. 31 (1977)]. 

4See also statement of Senator Muskie, 123 Cong. Rec. S9171 

(June 8, 1977). 
P.17 

14 

BACT, be it top-down, the method embodied in the 1979 

guidance, or otherwise, EPA interprets the relevant Act 

provisions as embodying two core legal criteria that must be 

satisfied in any BACT analysis.5 First, the permit 

applicant must consider a representative group of available 

control technologies [i.e., technologies that are 

representative of the range of available controls that are 

at least as effective as the minimum permissible (NSPS 

limit, § 112 limit, or SIP limit)]. Second, selection of a 

particular control system as BACT must be justified by a 

comparison of the candidate control systems in terms of the 

statutory criteria and supported by the record in such a way 

that the basis for the choice of BACT from among the other 

Application of EPA's earlier top-down guidance may have had 

the unintended effect of constraining State discretion in making 

BACT determinations and absolutely precluding consideration of 

certain cost and environmental factors (e.g., incremental cost 

effectiveness and incremental ambient impacts). Also the 

Administrator's decision in Union County Resource Recovery 

Facility, PSD Appeal No. 90-1 (Nov. 28, 1990) at 8, could be 

improperly construed as precluding any comparison of candidate 

control technologies in light of the applicable statutory 

factors. Together, this may have created an unduly strong 

presumption that the most stringent level of control is BACT. 

Permitting authorities wishing to follow a top-down method in the 

future should be sure that the method is consistent with the core 

criteria and does not ignore relevant factors. 
P.18 

15 

candidate systems is apparent and consistent with statutory 

criteria.6 

The EPA is today proposing guidance consistent with the 

PSD regulations. The EPA continues to recognize that the 

Act and existing regulations for BACT mandate application of 

the two core criteria discussed above. Rather than further 

advocating adherence to the top-down methodology, the Agency 

is instead emphasizing the broad flexibility which 

permitting authorities have in conducting the requisite BACT 

analysis. Indeed, EPA is today proposing to codify the core 

criteria into its regulatory definition of BACT. At the 

same time, however, the legislative history to the Act 

,; demonstrates that Congress favored broad flexibility for 

States in applying the statutory factors (i.e., energy, 

environmental, and economic impacts) in determining BACT. 

With this purpose in mind, EPA believes that so long as the 

core criteria are applied as described herein, Congress' 

interests in stimulating advances in pollution control 

technology and preserving the flexibility of the permitting 

6In this regard, to the extent that a rationale for the 

rejection of the next more stringent alternative than the one 

proposed also provides the basis for rejection of other more 

stringent alternatives, there is no need to conduct a separate, 

detailed analysis for each more stringent option. To give an 

example, assume that after examining a control option in detail, 

the permitting authority accepts an applicant's proposal to 

reject a control option due to an adverse economic impact after 

considering the energy, environmental, and other economic impacts 

of that option. The permitting authority need not consider the 

other more stringent control options in detail, if it concludes 

that their associated energy, environmental, and economic impacts 

do not differ meaningfully from the control option rejected. 
P.19 

16 

authority are best accomplished without requiring 

utilization of the top-down methodology. In this way, 

permitting authorities are free to develop their own BACT 

implementation policies and consider factors that exist for 

a proposed facility on a case-by-case basis within the 

statutory and regulatory framework for a BACT analysis. 

In light of this, to the extent the Agency's earlier 

top-down guidance efforts, including the Honolulu Power and 

Pennsauken County PSD appeals, apply a top-down approach 

that could be read to restrain State discretion in weighing 

the statutory factors and could be read as being 

inconsistent with congressional intent that the State retain 

broad discretion to weigh the statutory factors or to 

preclude comparing candidate controls using an incremental 

impact analysis and applying other statutory criteria, those 

decisions no longer reflect EPA policy. As stated above, 

the primary benefit to the top-down methodology was that it 

would ensure application of the BACT core criteria by 

permitting authorities. However, earlier efforts had the 

potential to chill the full exercise of a State's discretion 

by announcing core criteria that could be construed to 

create an unduly strong presumption in favor of the most 

stringent pollution control alternative available. By 

proposing to promulgate the core criteria (as reformulated 

today) by regulation, EPA believes it has adequately 
P.20 

17 

implemented the Act, including the congressional intent that 

broad discretion remain with the permitting authority. 

In the context of earlier appeals to the Administrator, 

questions have arisen over State discretion to consider the 

incremental ambient and cost impacts associated with certain 

pollution control options, relative to the other available 

options, in determining BACT [see Columbia Gulf Transmission 

Co., PSD Appeal No. 88-11 (Order, June 21 1989); World Color 

Press. Inc., PSD Appeal No. 88-4 (Remand Order, December 13, 

1990)]. In those decisions, in contrast to earlier EPA 

guidance (e.g., the 1980 PSD Workshop Manual page I-B-35), 

the Administrator determined that the environmental impacts 

prong of the BACT analysis precluded analysis as to whether 

use of the more stringent control alternative would benefit 

ambient air quality, or whether the additional benefit was 

worth the expense. However, the Administrator did recognize 

that, under certain circumstances, such considerations may 

be appropriate under the economic impacts prong of the BACT 

analysis. Underlying these decisions was the view that, 

under the Act, there is a distinction between BACT, which is 

concerned with pollution control technology, and ambient 

impacts, which relates to overall air quality [see 

42 U.S.C. 7475(a)(3) and (4)]. 

While the EPA continues to recognize that BACT is 

primarily directed to technology selection, and that this is 

somewhat distinct from impacts upon ambient air quality, EPA 
P.21 

18 

does not believe the Act or implementing regulations mandate 

absolute separation of the two concepts. Rather, the 

selection of an appropriate technology as BACT is 

sufficiently related to the Act's overriding concern with 

air quality that a permitting authority may, in its 

discretion and as part of its overall BACT analysis, 

consider the relative ambient impacts of the available 

control alternatives. Although this type of analysis may 

occur under either the economic or environmental prong of 

the BACT analysis (thus modifying recent decisions by the 

Administrator, albeit in a manner consistent with statements 

in EPA's 1980 Workshop Manual), the permitting authority 

; must continue to consider the full range of statutory 

factors before issuing the final permit. This approach is 

consistent with EPA's 1980 Workshop Manual and recognizes 

Congressional intent that the States retain broad 

discretion and flexibility in making BACT determinations.7 

Even though States have discretion to consider incremental 

ambient and economic impacts, they must also consider, in 

accordance with their overall BACT policy, all of the other 

statutory factors in the BACT analysis. These can, for 

example, include consideration of source specific factors, 

such as locally sensitive environmental resources; proximity 

7In such cases, the analysis should rely on the model and 

model inputs used in conducting the requisite PSD ambient air 

quality analysis (i.e., the determination that new emissions will 

not cause or contribute to a violation of the applicable NAAQS or 

PSD increments). 
P.22 

19 

to Class I areas; overall increment management; 

acidification; or visibility impairment.8 Thus, a State may 

not rely solely upon pre-set ambient impact or costeffectiveness levels in selecting BACT, but must justify its 

selection in terms of all the statutory factors (although 

such levels may be utilized by a State to assist it in 

making its determination). 

In a BACT analysis, the representative group of control 

technologies initially considered shall include the most 

8In some cases, the lack of comprehensive information or 

modeling tools limits the application of such analyses. However, 

in making its final BACT determination, the State is not 

constrained by limitations to modeling technology or the 

difficulty in assessing environmental impacts. If a State lacks 

the ability to definitively quantify the impacts upon air quality 

or air quality related values, or prefers to not rely upon such 

measures, it nevertheless retains discretion to manage 

its air resources through reliance upon qualitative determination 

or reasonable approximation in making its final BACT selection. 
P.23 

20 

stringent control technology available.9 However, there is 

no requirement that each alternative be evaluated in equal 

depth. Under the statutory design, PSD permitting 

authorities for each jurisdiction have broad discretion to 

reflect local conditions and preferences in weighing the 

energy, environmental, and economic factors that enter into 

a BACT determination. For example, States could adopt a prescreening process. An initial, limited analysis may 

conclude that certain alternatives are unlikely to be 

considered BACT based upon the most recent information 

available concerning cost, feasibility, and other relevant 

factors pertaining to those alternatives, and upon the 

: permitting authority's general approach to weighing the 

'Whether a technology is "available" for purposes of BACT is 

a practical, factual determination, using conventional notions of 

whether the technology can be put into use [see Pennsauken 

County, New Jersey Resource Recovery Facility. PSD Appeal 

No. 88-8 (Remand Order, Nov. 10, 1988) at 8]. The permit 

applicant should refer to the BACT/LAER Clearinghouse when 

identifying a representative group of available control 

technologies. Each type of selected control system (e.g., a 

baghouse, an electrostatic precipitator, a dry scrubber, a wet 

scrubber, a carbon absorber) or combination of control systems 

should be analyzed at the technically achievable level of control 

as it could be applied at the proposed facility. Major 

alternatives within a given type of control system should also be 

considered when such alternatives would produce meaningfully 

different energy, environmental, or economic impact or other 

costs than the initial level of control analyzed. On the other 

hand, analyses of numerous minor variations in a control system 

(or combinations thereof) is not required. In EPA's experience, 

typically there are only at most four or five BACT options that 

need be reviewed in detail for any proposed source in order to 

ensure that a representative sample of alternatives is 

considered. 
P.24 

21 

statutory factors. Such a screening of potential BACT 

options to identify the most likely and promising may save 

the source and permitting authority time and money and 

provide a degree of predictability to all concerned. 

Where the permitting authority decides after 

considering any source-specific factors that the screenedout options would not be BACT, then the evaluation process 

would shift in the next step to the remaining "live" options 

for further analysis. For example, where a permitting 

authority has made explicit statements through, guidelines, 

prior BACT determinations, or otherwise, that based on the 

availability of one or more technologies and a weighing of 

relevant factors, a particular emission range is appropriate 

as a BACT limit, and if source-specific factors do not lead 

to a conclusion that another emission range would be more 

appropriate, then the more detailed aspect of the BACT 

analysis could be limited to technologies capable of 

performing in the initial range considered. If a State 

decides to adopt a screening process for BACT, sources 

applying for a BACT determination can focus analytical 

attention on those alternatives likely to be considered BACT 

by that authority. Of course, as always, the BACT analysis 

and decision must still be made on a case-by-case basis. 

Moreover, today's action does not require a State to follow 

the process as discussed above. If this approach is 

followed, however, the State's initial criteria should be 
P.25 

22 

set in an open public process and updated regularly. Also, 

in no case does an initial screening of options preclude the 

Administrator or any other person from questioning the 

appropriateness of the criteria in general or the 

application of those criteria in a specific permit. 

The two core criteria clarified in today's action are 

consistent with determinations in the administrative appeals 

decisions subsequent to the H-Power decision that 

application of the two core criteria relating to 

consideration of available technologies and to justify the 

chosen technology under the statutory factors are essential 

requirements of a BACT analysis. The Administrator's 

subsequent PSD appeal decisions have required that States 

use such core criteria in making BACT determinations. Thus, 

in Union County Resource Recovery Facility. PSD Appeal . 

No. 90-1 (11/28/90), the Administrator cited compliance with 

the two core criteria in upholding a BACT determination for 

a resource recovery facility. The Administrator relied on 

the same two core criteria in upholding a permit 

determination in Mecklenburg Cogeneration Limited 

Partnership, Clarksville, VA. PSD Appeal No. 90-7 

(12/21/90). 

Although EPA believes that the current statutory and 

regulatory definitions of BACT implicitly require the 

consideration of the two core criteria set forth in this 

notice, as fundamental to any adequate BACT determination, 
P.26 

23 

the criteria announced in earlier decisions need to be 

clarified to ensure that they do not restrict State 

discretion. The EPA is today proposing to make these 

requirements explicit by inserting into the regulatory 

definition of BACT the following two core requirements for a 

BACT analysis: 

1) the determination must consider a representative 

group of available control systems for the source, and, 

2) selection of a particular control system as BACT 

must be justified by a comparison of the candidate systems 

in terms of the statutory criteria and supported by the 

record. 

III. Impacts Analysis in a BACT PSD Determination 

In evaluating the alternative candidate control 

systems, an applicant must consider and compare the expected 

energy, environmental, and economic impacts of the 

alternatives. This section discusses some specific impacts 

which may affect the final technology ultimately selected, 

and presents a set of potential factors, any number of which 

may be addressed in a permit application depending on the 

individual situation. The energy, environmental, and 

economic impacts discussed below are illustrative only and 

are not intended as an exclusive list of considerations for 

BACT. Some of these factors may not be appropriate in all 

cases, while in other instances, factors which are not 
P.27 

24 

included here may be relevant to the BACT determination. 

For example, if a control system produces a known quantity 

of solid waste as a by-product inherent to its design and 

operation under normal conditions, such an impact should be 

noted in the PSD permit application. However, this factor 

need not be analyzed in detail, unless the applicant wishes 

to use solid waste impacts as an argument for or against 

selection of a particular control alternative as BACT. The 

discussion does not address the evaluation of each factor 

nor the weighing of any factor relative to another. Such 

determinations should be made on a case-by-case basis by the 

permitting authority. For the purpose of this discussion, 

the terms "emission control system" or "BACT system" refer 

to the "application of production processes and available 

methods, systems, and techniques, including fuel cleaning, 

clean fuels, or treatment or innovative fuel combustion 

techniques" [see § 169(3), as amended by § 403(d) of the 

1990 Amendments]. 

In general, the BACT analysis should address the direct 

impacts of alternative control systems. Usually, direct 

impacts are experienced on-site [e.g., scrubber sludge 

disposal sites]; however, they could also be off-site. For 

example, ammonia slip is not limited to the plant boundary. 

Duplicative analyses generally are not required in 

preparing the BACT permit application. Any studies 

previously performed for Environmental Impact Statements, 
P.28 

25 

water pollution permits, or other programs may be used when 

appropriate to demonstrate adverse energy, environmental, or 

economic impacts. 

The same considerations are generally applicable to 

both new and modified sources. Where appropriate, however, 

the permit review may consider any special economic or 

physical constraints which might limit the application of 

certain control techniques to a modified emissions unit, 

such as retrofitting costs that would not be borne by a new 

unit, or the remaining useful life of the modified facility. 

The result may be that the level of control required for an 

emissions unit undergoing modification may not be as 

stringent as that which would be required if the same unit 

were being newly constructed at an existing plant or at a 

"greenfield" facility. This observation is meant only to 

illustrate that the BACT decision must be made on a case-bycase basis by the permitting authority considering the 

relevant energy, environmental, and economic impacts. 

A. Energy Impacts 

Energy impacts should address energy use in terms of 

penalties or benefits associated with a control system and 

the direct effects of such energy use on the facility. A 

source may, for example, benefit from the combustion of a 

concentrated gas stream rich in volatile organic compounds; 

on the other hand, extra fuel or electricity is frequently 

required to power a control device or incinerate a dilute 
P.29 

26 

gas stream. If such benefits or penalties exist, they 

should be quantified to the extent possible. 

In quantifying energy impacts, the applicant could 

estimate the direct energy impacts of the control 

alternative in units of energy consumption at the source 

(e.g., Btu, Kwh, barrels of oil, tons of coal). The energy 

requirements of the control options could be shown in terms 

of total and/or incremental energy costs per total and/or 

incremental ton of pollutant removed in comparison to the 

next higher and lower control options. In many cases, 

because energy penalties or benefits can usually be 

quantified in terms of additional cost or income to the 

source, the energy impacts analysis can be converted into 

dollar costs and, where appropriate, be factored into the 

economic impacts analysis. 

Indirect energy impacts (such as energy to produce raw 

materials for construction of control equipment) are usually 

not considered. However, if the permit authority 

determines, either independently or based on a showing by 

the applicant, that an indirect energy impact is unusual or 

significant, the indirect impact may be considered. The 

energy impact should still, however, relate to the 

application of the control alternative and not to a concern 

over energy impacts associated with the project in general. 

The energy impact analysis may also address the concern 

over the use of locally-scarce fuels. The designation of a 
P.30 

27 

scarce fuel may vary from region to region, but in general a 

scarce fuel is one which is in short supply locally and can 

be better used for alternative purposes, or one which may 

not be reasonably available to the source either at the 

present time or in the near future. 

B. Environmental Impacts. 

The environmental impacts analysis in the BACT 

evaluation process concentrates on collateral environmental 

impacts due to control of emissions of the pollutant in 

question, such as solid or hazardous waste generation, 

discharges of polluted water from a control device, 

visibility impacts (e.g. visible steam plume), or emissions 

• of toxic pollutants, and, in the State's discretion, ambient 

air quality impacts of the control system under 

consideration. The applicant should identify any 

environmental impacts associated with a control alternative 

that have the potential to affect the selection or rejection 

of that control alternative. 

Potentially significant, secondary environmental 

impacts must also be evaluated. Scrubber effluent, for 

example, may affect water quality and land use, and, 

similarly, technologies using cooling towers may affect 

visibility. Other examples of secondary environmental 

impacts could include hazardous waste discharges, such as 

spent catalysts or contaminated carbon. Generally, these 

types of environmental concerns become important when 
P.31 

28 

sensitive site-specific receptors exist or when the 

incremental emissions reduction potential of one control 

option is only marginally greater than the next most 

effective option. 

The BACT decision can consider State policy decisions 

regarding use of the available air quality increment for 

future growth and the weighing of this factor. As discussed 

above, the direct impact of the controls on ambient 

concentrations may also be identified and considered in the 

BACT analysis. Incremental changes in ambient impacts of 

alternative control systems may be assessed and compared, 

along with cost data on controls, to determine whether a 

different level of control is justifiable in light of the 

related environmental benefits or is needed to carry out a 

State's decision on the allocation of the available 

increment.10 

The procedure for conducting an analysis of 

environmental impacts should be made based on consideration 

of site-specific circumstances. In general, the analysis of 

environmental impacts starts with the identification and 

quantification of the solid, liquid, and gaseous discharges 

from the control device (or devices) under review. 

10In today's rulemaking, EPA affirms that any applicant may 

provide an incremental ambient analysis as part of its BACT 

submissions, and if so, the State should consider it in making a 

BACT determination (see e.g., footnote 3 above). Likewise, a 

State may request such analysis of any applicant as part of its 

BACT process. Moreover, EPA intends to provide guidance on how 

these issues may be addressed by states and applicants. 
P.32 

29 

Regarding secondary effects, a qualitative or semiquantitative screening can be performed to narrow the 

analysis to discharges with potential for causing adverse 

environmental effects. Next, the mass and composition of 

any such discharges should be assessed and quantified to the 

extent possible, based on readily-available information. As 

previously mentioned, the analysis need only address those 

control alternatives with any environmental impacts that 

have the potential to affect the selection or rejection of a 

control alternative. Pertinent information about the public 

or environmental consequences of releasing these materials 

should also be assembled. Thus, the relative environmental 

impacts (both positive and negative) of the various 

alternatives can be compared with each other. 

Also the generation or reduction of toxic and hazardous 

emissions using the various BACT alternatives, including 

compounds not regulated under the Act or the PSD program, 

are considered as part of the environmental impacts 

analysis. Pursuant to the EPA Administrator's decision in 

North County Resource Recovery Associates. PSD Appeal 

No. 85-2 (Remand Order, June 3,1986), a PSD permitting 

authority should take into account the ability of a given 

control alternative for regulated pollutants to affect 

emissions of pollutants not subject to regulation under the 

Act or the PSD program in making BACT decisions. 

Consequently, the affect of a given control alternative upon 
P.33 

30 

the emission of toxic or hazardous air contaminants must be 

evaluated in conducting the BACT analysis. 

C. Economic Impacts 

This analysis should address the economic impacts 

associated with the costs (including incremental costs) of 

installing and operating alternative control systems. 

Normally the submittal of very detailed and comprehensive 

project cost data is not necessary. 

In the economic impacts analysis, consideration should 

be given first to quantifying the cost of the various 

control options. The review should include a complete 

explanation of procedures for assessing economic impacts and 

: any supporting data. 

Once the control technology alternatives and emissions 

performance levels have been identified, capital and annual 

costs are developed. The direct cost for each control 

alternative should be presented both on an incremental and 

an overall basis. Investment costs, operation and 

maintenance costs, and annualized costs should be presented 

separately. Annualized costs are operation and maintenance 

costs plus depreciation and interest charges on the 

investment. Costs should be itemized and explained. Credit 

should be included for product recovery costs and by-product 

sales generated from the use of control systems, including 

the sale of sulfur dioxide allowances under the acid rain 

program and other emission reduction credits. The lifetime 
P.34 

31 

of the investment should be stated. Where possible, costs 

should be broken down into process change costs (costs of 

less polluting production process) and direct pollution 

abatement costs (cost of pollution control equipment). The 

costs of air treatment, water treatment, and solid waste 

disposal should be presented separately. The objective of 

the analysis is to provide a realistic estimate of the costs 

of the alternative technologies. 

As a guide in determining when control costs become 

excessive, alternative control systems can be compared in 

terms of the incremental cost effectiveness of the available 

alternatives. Thus, as an example, an analysis focusing on 

I a comparison of the incremental economic and corresponding 

environmental (e.g., air quality) impacts of the BACT 

candidates and that addresses all of the relative statutory 

factors would be sufficient. States can evaluate whether 

the incremental cost effectiveness of a more stringent 

option is appropriate in light of other relevant experience 

(e.g., recent BACT determinations) and other factors 

involved in the BACT decision and the State's weighing of 

these factors. Incremental, cost-effectiveness calculations 

are generally performed on the basis of incremental dollars 

per ton of additional pollutant removed. 

In addition to the types of economic impacts discussed 

above, EPA is today soliciting comment on whether the 

economic impacts analysis should consider as impacts the 
P.35 

32 

affordability of controls by the firm in response to 

alternative levels of control. For example, a more costly 

BACT alternative could be presented as altering the 

economics of a project to the point where a decision would 

be made to cancel the construction or expansion of a 

facility, to relocate a plant, to reduce the scale of 

operation, or to change the production mix. In such cases, 

the local economic impacts of such decisions (e.g., local 

employment effects, including number of jobs, dollars paid 

in salaries, and changes in employee skill levels required) 

would be evaluated and factored into the economic analysis. 

Comments should address the reasonableness and practicality 

of including such considerations in the BACT analysis.11 

IV. Purpose of the Proposed Change 

The approaches set forth in the various EPA final and 

draft guidance documents have been intended to guide permit 

applicants and permitting officials in those areas subject 

to the Federal PSD regulations at 40 CFR 52.21. They have 

not established binding regulatory requirements, which are 

contained in the Federal regulations and SIP's. Rather than 

specifying a precise approach to the BACT analysis, EPA is 

proposing today to clarify two core legal requirements that 

"The EPA's 1979 guidance discussed the use of affordability 

considerations. However, in 1987, EPA adopted a policy that 

affordability should not be a factor in BACT analyses. The EPA 

is now revisiting the issue. 
P.36 

33 

are necessary for an adequate BACT analysis under existing 

law. In reviewing new or revised State PSD rules.submitted 

for SIP approval, the Agency will deem the program to be 

adequate.if it specifies that these two requirements are 

necessary for an adequate BACT analysis. Likewise, in 

fulfilling its oversight and enforcement responsibilities, 

the Agency will continue its policy of reviewing specific 

permitting actions for conformity with the core criteria. 

So long as the State has carefully evaluated each candidate 

system, justified the choice of one over each of the others 

in terms of the statutory criteria, otherwise followed the 

procedural norms embodied in the core criteria, and ensured 

;, the decision would not violate any objective standards that 

may apply (such as NSPS or SIP limits), EPA will consider a 

State's BACT analysis to be adequate and will not secondguess the State's substantive BACT decision. Thus, under 

today's proposal, adherence to any specific BACT approach, 

such as top-down or bottom-up, is not required. Rather, 

today's proposal is intended to ensure adherence to the core 

criteria such that States make reasoned and informed BACT 

determinations in a publicly-accountable manner. Further, 

the States have wide discretion in setting the weight 

assigned to each statutory factor (energy, environmental, 

economic and other costs) in comparing and balancing the 

relative effects of the various BACT options. Whichever 

approach is selected, the BACT analysis should include a 
P.37 

34 

complete explanation of the procedures used by the State to 

assess the energy, environmental, and economic impacts and 

any supporting data. Permits containing BACT determinations 

that do not conform to the PSD requirements of the Act, EPA 

regulations, and applicable SIP's, as reflected in the core 

criteria, will be considered deficient by EPA. Instances of 

procedural irregularities or arbitrary decision making will 

remain grounds for SIP calls, permit appeals, or enforcement 

action, as appropriate. 

The EPA is today soliciting comment on the proposed 

clarification to the BACT definition for the purpose of 

clarifying and delineating the regulatory standard by which 

the adequacy.of a BACT determination should be judged. As 

noted above, EPA already recognizes that there are a variety 

of permissible methods, including the top-down method, for 

determining BACT. State permitting authorities are free to 

apply the core legal criteria without reference to any 

exclusive method in making BACT determinations that satisfy 

the Act. Of course, the BACT analysis and selection process 

is but one part of a complete PSD review, and the BACT 

emissions limitations must be consistent with all other PSD 

requirements. 

V. Clean Fuels 

The definition of BACT in § 169(c) of the Act is 

changed by § 403(d) df the 1990 Amendments. To maintain 
P.38 

35 

conformity with the statutory definition, EPA proposes to 

amend the regulatory definition of BACT at 

40 CFR 52.21(b)(12) and 51.166(b)(12) by inserting "clean 

fuels" after "including fuel cleaning," and by adding the 

following at the end thereof: "Emissions from any source 

utilizing clean fuels, or any other means, to comply with 

this paragraph shall not be allowed to increase above levels 

that would have been required under this paragraph as it 

existed prior to enactment of the Clean Air Act Amendments 

of 1990." 

VI. Miscellaneous 

A. Docket. 

A docket has been established for this action under 

§ 307(d)(1)(I) and (N) of the Act, 42 U.S.C. 7607(d)(1)(I) 

and (N). The docket is an organized and complete file of 

all information considered in the development of this 

ruling. The docket is intended to allow the public to 

identify and locate documents related to this ruling. The 

docket number for this ruling is A-91-30. 

B. Paperwork Reduction Act. 

No additional public reporting burden will result from 

this ruling. All information collection requirements of the 

Federal NSR regulations have been approved by the Office of 

Management and Budget (OMB) under the provisions of the 

Paperwork Reduction Act, 44 U.S.C. 3501, et*. seq., and have 

been assigned OMB control number 2060-0003. The effect of 
P.39 

36 

this rule would be no change in paperwork related to 

complying with NSR requirements, since this ruling only 

provides additional clarification regarding the regulatory 

definition of BACT. 

C. The E.O. 12291. 

Under E.O. 12291, EPA must judge whether a rule is 

"major" and therefore subject to the requirement of a 

regulatory impact analysis. This ruling is not a major rule 

because it will not change the economic costs of meeting the 

requirements of the Act. However, this ruling was submitted 

to OMB for review. Written comments from OMB to EPA and any 

EPA response are included in Docket A-91-30. 

D. Economic Impact Assessment. 

The requirement for performing an Economic Impact 

Assessment under § 317 of the Act (42 U.S.C. 7617), does not 

apply to the amendments EPA is promulgating today. Section 

317 applies only to "revisions which the Administrator 

determines to be substantial revisions." The ,proposed 

clarifying language is not a substantial revision because it 

does not change current regulatory burdens. 

E. Regulatory Flexibility Act. 

This action is not subject to the certification 

provisions of § 605(b) of the Regulatory Flexibility Act 

because this rule will not result in a change in 

administrative costs or an increase in control costs, 
P.40 

37 

therefore having no significant impact on industry or small 

communities. 

F. Effective Date. 

Section 4(d) of the Administrative Procedures Act, 

5 U.S.C. 553(d), requires a 30-day waiting period before 

making a substantive rule effective. Although the 

regulatory revisions being proposed today are not considered 

substantive, they are being subject to notice-and-comment 

and will become effective only after public comments have 

been received and considered, and final action has been 

taken. 

••List of Subjects 40 CFR Parts 51, 52 

Administrative practices and procedure, 

Intergovernmental relations, Air pollution control, NSR, 

BACT, Sulfur oxides, Nitrogen dioxide, Particulate matter, 

Carbon monoxide, Hydrocarbons, Lead, Ozone, Reporting and 

recordkeeping requirements, Volatile organic compounds, 

NSPS, NESHAP. 

Authority: 42 U.S.C. 7401(b)(1), 7410, 7411, 7470-

7479, 7491, 7501-7508, 7601 and 7602, as amended by the 1990 

Amendments, Pub. L. No. 101-549, 104 Stat. 2399 (Nov. 15, 

1990); 402, 409, 415 of the Act as amended, 104 Stat. 2399; 

42 U.S.C. 7401-7642 as amended by the 1990 Amendments, Pub. 

L. No. 101-549, 104 Stat. 2399 (Nov. 15, 1990); 42 U.S.C. 
P.41 

38 

7401, 7411, 7414, 7416, and 7601 as amended by the 1990 

Amendments, Pub. L. No. 101-549, 104 Stat. 2399 (Nov. 15, 

1990); 402, 409, 415 of the Act as amended, 104 Stat. 2399, 

unless otherwise noted. 

Dated: 

William K. Reilly 

Administrator 
P.42 

39 

For the reasons set forth in the preamble, Part 51 of 

Chapter I of Title 40 of the Code of Federal Regulations is 

proposed to be amended as follows: 

Part 51 - REQUIREMENTS FOR PREPARATION, ADOPTION, AND 

SUBMITTAL OF IMPLEMENTATION PLANS. 

1. Section 51.166 is proposed to be amended by 

revising paragraph (b)(12) to read as follows: 

51.166 Prevention of significant deterioration of air 

quality . 

* * * * * 

(b) * * * 

(12) Best available control technology means an 

. emissions limitation (including a visible emissions 

standard) based on the maximum degree of reduction for each 

pollutant subject to regulation under the Act, which would 

be emitted from any proposed major stationary source or 

major modification which the reviewing authority, on a caseby-case basis, taking into account environmental, energy, 

and economic impacts and other costs, determines is 

achievable for such source or modification through 

application of production processes or available methods, 

systems, and techniques, including fuel cleaning, clean 

fuels, or treatment or innovative fuel combustion techniques 

for control of such pollutant. Two criteria must be 

satisfied in any BACT analysis: 
P.43 

40 

1) the determination must consider a representative 

group of the range of available control systems for the 

source; and 

2) selection of a particular control system as BACT 

must be justified by a comparison of the candidate control 

systems in terms of the statutory criteria and supported by 

the record. In no event shall application of BACT result 

in emissions of any pollutant which would exceed the 

emissions allowed by any applicable standard under 40 CFR 60 

and 61. If the Administrator determines that technological 

or economic limitations on the application of measurement 

methodology to a particular emissions unit would make the 

imposition of an emissions standard infeasible, a design, 

equipment, work practice, operational standard, or 

combination thereof, may be prescribed instead to satisfy 

the requirement for the application of BACT. Such standard 

shall, to the degree possible, set forth the emissions 

reduction achievable by implementation of such design, 

equipment, work practice, or operation, and shall provide 

for compliance by means which achieve equivalent results. 

Emissions from any source utilizing clean fuels, or any 

other means, to comply with this paragraph shall not be 

allowed to increase above levels that would have been 

required under this paragraph as it existed prior to 

enactment of the 1990 Amendments. 
P.44 

41 

Part 52 - APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS. 

1. Section 52.21 is proposed to be amended by revising 

paragraph (b)(12) to read as follows: 

51.21 Prevention of significant deterioration of air 

quality. 

* * * * * 

(b) * * * 

(12) Best available control technology means an 

emissions limitation (including a visible emissions 

standard) based on the maximum degree of reduction for each 

pollutant subject to regulation under the Act which would be 

emitted from any proposed major stationary source or major 

modification which the Administrator, on a case-by-case 

basis, taking.into account environmental, energy, and 

economic impacts and other costs, determines is achievable 

for such source or modification through application of 

production processes or available methods, systems, and 

techniques, including fuel cleaning, clean fuels, or 

treatment or innovative fuel combustion techniques for 

control of such pollutant. Two criteria must be satisfied 

in any BACT analysis: 

1) the determination must consider a representative 

group of the range of available control systems for the 

source; and 

2) selection of a particular control system as BACT 

must be justified by a comparison of the candidate control 
P.45 

I * , 

42 

systems in terms of the statutory criteria and supported by 

the record. In no event shall application of BACT result 

in emissions of any pollutant which would exceed the 

emissions allowed by any applicable standard under 40 CFR 60 

and 61. If the Administrator determines that technological 

or economic limitations on the application of measurement 

methodology to a particular emissions unit would make the 

imposition of an emissions standard infeasible, a design, 

equipment, work practice, operational standard, or 

combination thereof, may be prescribed instead to satisfy 

the requirement for the application of BACT. Such standard 

shall, to the degree possible, set forth the emissions 

reduction achievable by implementation of such design, 

equipment, work practice, or operation, and shall provide 

for compliance by means which achieve equivalent results. 

Emissions from any source utilizing clean fuels, or any 

other means, to comply with this paragraph shall not be 

allowed to increase above levels that would have been 

required under this paragraph as it existed prior to 

enactment of the 1990 Amendments.