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OAR Box 1793 

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Document Number: 

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Docket Number: 

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27 

project exclusion with a new pollution control project exclusion 

for all .source categories.8 

C. The "Clean Unit" and "Clean Facility" Exclusion 

1. Introduction 

The Applicability Subgroup of the CAAAC's NSR Reform 

Subcommittee considered many applicability options. While none 

of these proposals garnered the full Subcommittee's support> 

representatives of State and local regulators as well as 

environmental groups expressed general' support for the idea that 

"benign" changes at existing emissions units do not need to 

undergo the actual-to-potential test and the complicated NSR. 

netting rules in every instance. There was also support for the 

proposition that the NSR applicability test should provide some 

deference to sources that have already undergone major NSR. 

. The EPA, after careful consideration of these discussions, 

believes that the best approach for a new exclusion is- one that 

focuses on the existing emissions control of a'unit, rather than 

1 In the WEPCO Rule, the EPA also created special new 

source performance standard (NSPS) treatment for certain 

repowering projects and provided limited NSR exemptions for • 

temporary and permanent Clean Coal Technology projects, and for 

certain "very clean" units. See e.g., existing section H 

51.166 (bM2) (iil) (i) , (j..) and (Js) ]• All of these changes 

implemented special provisions in the Clean Air Act. Amendments of 

1990. In the rule, the EPA also amended its NSPS regulations (40 

CFR part 60) to allow a'utility to use as its pre-change baseline 

its highest hourly emissions rate achieved during the 5 years 

prior to the proposed physical or operational change. The 

changes implementing the NSPS baseline change are neither 

discussed nor affected by today's rulemaking proposal. 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

**• July 5, 1995 [file name: Master6.29] *** 
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2 8 '•'.' • 

the change being proposed. Almost all stakeholders identified 

the goal, of ensuring that modified units apply state-of-the-art -

controls as being of paramount importance. Accordingly, where an 

emissions unit already meets this goal, environmental concerns 

associated with proposed changes are likely reduced. For 

example, it is the EPA's experience that in many cases where an 

existing well-controlled unit triggers major NSR, the permitting 

process does not necessarily result in improved controls. On the 

other hand, where the review, is focused on units which have not 

recently been required to meet a control technology requirement, 

NSR can be expected to result in more stringent controls and 

meaningful reductions in actual emissions. 

Similarly, where an entire facility already meets the goal 

of the application of state-of-the-art controls and has undergone 

an air quality impact analysis of. its emissions, environmental 

concerns associated with proposed changes are likely reduced if 

the changes.remain consistent,with requirements imposed by the 

analysis. . Thus, EPA is also proposing a "clean" facility 

exclusion that allows a major stationary source to make changes 

at its facility consistent with PSD or NSR permits that have been 

recently issued. 

2. Description of the Clean Unit Proposal 

Based on these' factors, the EPA is today proposing a 

simplified applicability test for changes to existing emissions 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

*** July 5, 1995 --- [file name: Master6.29J *** 
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2 9 

units that already have state-of .-the-art emission controls. In 

•general, this new "clean unit" exclusion will allow States to 

exclude from major NSR, proposed changes.to existing emissions 

units that have installed major BACT or LAER or which otherwise. 

qualify as a "clean unit." Under this exclusion, sources can 

make any change to a qualifying unit so long as the change will, 

not increase the unit's emissions rate (measured in terms of the 

unit's. maximum hourly emissions, the new source performance 

standard (NSPS) test found at existing 40 CFR 60.14). 

Specifically,, changes which do not .increase the unit's hourly 

potential emissions would not be considered a physical or 

operational change and thus would not trigger major NSR;9 See 

proposed sections 51.165 (a)(1) (v) (C) (10) , 51.166(b) (2) Uii)'(L) 

and 52'.21 (b) (2) (iii) (L) . The proposed "clean unit" exclusion 

9 Under today's proposal, for units that are permitted to 

change feedstocks frequently, such as pharmaceutical 

manufacturing and certain chemical batch processes, the maximum 

hourly emissions rate test would be applied on a per. feedstock 

basis to determine.if an emission increase will occur. For 

example,- a unit which has state-of-the-art VOC eontrol technology 

and uses toluene and other organic solvents as feedstocks, the 

hourly maximum emission rate of toluene before and after the 

proposed physical or operational change would be assessed as if 

toluene alone was to be fully utilized by the- unit before and 

after the proposed change. The other feedstocks'would alsq be 

individually assessed. A change in feedstock would not trigger 

NSR if the control technology designed to control, emissions 

resulting from the "feedstock and the unit was previously 

permitted to use the feedstock. The EPA encourages suggest16ns 

in developing rules or guidance on other approaches for 

.determining emissions increases for processes with rapidly 

changing and mixed feedstocks. 

i ' - " . • 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

*** July 5, 1995 [file name: Master6.29] *** 
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would both simplify the applicability test for qualifying units 

and increase source flexibility. It would also reward sources 

that have applied stringent, controls to their emissions units. 

Ideally, the change in hourly potential emissions would be 

assessed immediately before and after the change to. determine if 

an emissions increase did indeed occur. However, this may not be 

practical in many instances because information necessary to 

establish the hourly potential emissions rate may require 

"tonsiderable time to develop or collect. Therefore, under the 

proposed provision, the pre-change hourly potential emission rate 

may be established or verified at any time up to 6 months prior 

to the proposed activity or project. The EPA solicits comment on 

alternative periods for establishing the pre-change hourly 

emissions rate, particularly periods which might allow the use of 

routine compliance emissions tests to determine the emissions 

rate (e.g., annual). Also under the proposed provision, where 

the unit is subject to a federally enforceable limit on 

operations or emissions which'limits the 'unit's hourly potential 

emissions to less than the maximum, physically achievable hourly 

rate, the unit's lower allowable rate, must be used in determining 

if an emissions increase will occur at the unit. " 

. 2.. What Constitutes a ".Clean Unit" 

For chis exclusion to function, it is necessary to . 

* 

distinguish a well-controlled unit from a poorly controlled one. 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

*** July 5, 1995 [file name: Master6.29] *** 
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In other words, what criteria distinguish a unit eligible for 

this exclusion from one which is not? Criteria which allow a 

broad-range of units to qualify could largely transform the 

existing applicability system into one based solely on assessing 

a unit's potential emissions, with the possibility of a dramatic 

increase in a unit's actual emissions without undergoing NSR. 

The EPA's proposes.to require emissions units to have a 

"federally enforceable emissions limit" that "is comparable to 

••^-^aaaaa.^-aaaa^.^^^^m^^ ^ 

the emission limit that . . .would result from'a current-review" 

under the BACT or LAER requirements, whichever is applicable to 

the proposed change. (See, e.g.. proposed sections 

51.165(a) (1) (v) (C) (20) (ii), 51.166(b)(2) (iiD (D.(2) and 

52.21(b)(2)(iii)(L)(2).) The EPA envisions that three types of 

limits would qualify: (1) BACT, or LAER limits set within the last 

•10 years; (2) limits set by a State technolngy rfview program 

determined by EP& t'n he equivalent to the federal BACT or LAER 

programs,-, and (3) limits found on a case-by-case basis -- after 

notice and opportunity for public comment- r- to be equivalent to 

BACT oi: LAER limits. 

a. Units with BACT.or LAER Limits 

One starting point for. determining whether a unit is wellcontrolled is the level of control required to satisfy BACT (in 

attainmenc/Unclassified areas) or LAER (in nonattainment areas). 

For units which have recently undergone these reviews, rePRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

• BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

*** July 5, 1995 --- [file name: Master6.29] *** 
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3 2 

evaluation of the technology shortly after the source is 

constructed or modified to determine if the technology is still • 

"state-of-the-art" would likely result in very little or no 

incremental improvement in emissions control. Moreover, units, 

that are recently-permitted are far less likely to have" 

physically deteriorated and more likely to be running near 

permitted capacity, reducing the risk that changes to the unit 

will result in increased utilization and increased actual 

emissions. 

Therefore, the EPA is proposing that the new exclusion may 

presumptively apply to any unit which received a BACT or LAER 

limit in a currently applicable major NSR permit within 10 years 

of the proposed change under consideration. See proposed 

sections. 51.165(a) (1) (v) (C) (W (x) (1) / 51.166(b) (2) (iii) (L) (£) &) 

and 52.21(b) (2) (iii) (L)(£) (i). In other words, for the first 10 

years following issuance of a PSD or nonattainment NSR permit, 

units subject to BACT or LAER set in that permit are eligible for 

the clean unit exclusion. At least some members of the 

Subcommittee expressed concern that the ten year period is too 

long .given the improvement in control technology that.can occur 

in some source categories. For this reason, EPA solicits comment 

on using a shorter period such as five years as the length of the 

Clean Unit presumption derived froni a NSR permit. 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

***. July 5,, 1995 [file name: Master6.29] *** 
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. * I .-• 

33 

During consideration of the Clean Unit Exclusion, several 

participants suggested that units subject to maximum achievable 

control technology (MACT) or reasonably achievable control 

technology (RACT) should also automaticly qualify as clean units. 

A recently required MACT emissions limit, while not necessarily 

equal to BACT or LAER, is likely to result in significant 

^missions controls such that a BACT or LAER review would not . 

' necessarily result in significant additional emissions 

reductions. However, the EPA is also concerned that a MACT limit 

could be significantly less effective in limiting volatileorganic compound (VOC) emissions than BACT or LAER in many 

circumstances.. A MACT emission limit may adequately control a 

toxic VOC but could result in emission increases of pollutants 

subject to NSR. • For example, an incinerator installed to reduce 

a toxic VOC will increase nitrogen oxides (NOx) emissions emitted 

to the atmosphere. 

The EPA also has concerns with using Federal RACT. limits to 

presumptively qualify a unit as a clean unit. In nonattainment 

areas, a RACT emission limit is almost always much less stringent 

than current LAER and, in the EPA's view, often would be less 

stringent than a BACT limit. Further, in some instances RACT is 

based on the attainment needs of the area and not,a specific 

control technology standard. While EPA solicits comment on 

presumptively applying the clean unit exclusion test to units 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

*** July 5, 1995 . [file name: Master6.29] *** 
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',... " 34 • 

with Federal .MACT or RACT limits, the EPA is not inclined to do 

so across the board. Rather,' the EPA believes that MACT or RACT 

limits should be found to qualify for the Clean Unit exclusion 

using the case-by-case option described in section II.C.3.C 

. below. • . .',-'*- , : " ' 

b. State Technology Programs Equivalent to BACT or LAER, 

There are many emissions units at stationary sources that 

were permitted according to a State's minor NSR permitting 

program. While these units are. not controlled pursuant to a BACT 

or LAER limit, they still may have state-of-the-art controls. 

For instance, several jurisdictions have control technology 

reviews as part of State, local or tribal minor NSR program which 

requires new or modifying sources to meet emissions levels 

equivalent to major source control technology requirements.(BACT 

or LAER). For this reason, the EPA is proposing that permitting 

authorities may submit minor NSR control technology requirements 

for certification by the EPA that the minor NSR program requires 

control technology that would satisfy.the requirements for the 

clean unit exclusion. See proposed sections 

51.165(a) (1) (v) (C) (Ifi) (£) (1) , 51.166(b) (2) (iii) (L) (5J (ii) and 

52.21(b) (2) (iii) (L) (£•) (ii) . Once determined by EPA to be. 

equivalent,' all units subject to emissions limitation established 

under.the jurisdiction's minor NSR program would be eligible for 

the Clean Unit exclusion for the first 10 years following 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

*** July 5, 1995 [file name: Master6.29] *** 
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35 

issuance of the permit. The EPA'also solicits comment on whether 

a shorter period, such as 5 years, would be more appropriate. 

The EPA also solicits comment on the appropriate' standards 

for EPA to use'in determining whether a permitting authority's 

minor NSR program control technology requirements are "comparable 

to the BACT and LAER requirements. The EPA envisions that as a' 

minimum a ''pre--certified" minor NSR program comply with 40 CFR 

51.160-164. 

c. Qualification of Units on a Case-By-Case Basis 

In many cases an emissions unit not subject to major NSR is 

constructed or retrofitted with a control technology or strategy 

equivalent to the best controls applied in practice. This may 

occur when a source minimizes emissions in order to "net" a unit 

out of major NSR or applies controls to comply with other 

provisions of the Act. For this reason, the EPA's proposed 

regulations would allow a source having a limit on an emissions 

unit determined to.be equivalent to BACT or LAER.to qualify for 

the "clean unit" exclusion on a case-by-caee basis. Once a 

permitting authority makes this determination through a process 

involving notice and opportunity for public comment, the.unit 

would be eligible for the clean unit exclusion for the next five 

years. Ac with the other types of proposed clean unit 

exclusions, EPA requests.public comments on the proposed 

exclusion eligibility period, ffee proposed sections 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND . 

BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

*** July 5,1995 --- [file name: Masters.29] ••• 
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51.165(a) (l)(v) (C) (Ifi) (v) Q) , 51.166 (b) (2) (iii) (L) (1) (iii) and 

52.21(b) (2) (iii) (L) (£) (iii). 

The EPA proposes several alternative bases upon which a 

permitting authority could take to make the determination that a 

unit has an equivalent BACT or LAER emissions limitation. The 

first would be based on an average of BACT or LAER for equivalent 

or similar sources over a recent period of time (e.g., most 

recent three years). The second would be based on the unit's 

control level being within some percentage (e.g., five or. ten 

percent) of the most recent, or average of the most recent, BACl 

#1> i£ic

 . rJ*\ 

ns limit is u . "• 

or LAER levels .for equivalent or similar sources.. The EPA 

solicits comment on these approaches and on the general issues 

concerning whether and how.EPA should impose a.spec 

methodology for determining that a specific emissions 

"comparable" to the current BACT or LAER limit. 

For all of the above tests, the EPA realizes that, there are 

many source and emission unit categories for which BACT or LAER 

determinations do not exist, let alone recent determinations. 

For. these sources, the EPA proposes that their level of control 

be gauged against the control levei associated with BACT or LAER 

for emission units with similar-emission stream characteristics. 

That is, if the emissions unit were to undergo a BACT or LAER 

review today or recently, what technologies would be evaluated 

and what are the current BACT or LAER levels associated with; 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL IEPA POLICY 

*** July 5, 1995 [file name.: Master6.29] *** 
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. those technologies? Since this in effect requires the permitting 

authority to engage in a BACT or LAER review in order to qualify 

a unit for this exclusion, the EPA is asking for comment on other 

• approaches for qualifying units. 

' States are encouraged to use the permitting process required 

by title'V of the Act as the vehicle for determining and 

recording which units at a title V source can qualify for thisexclusion.10 . The permitting authority could use the title V 

permit issuance,; revision or renewal process as the mechanism for 

making the caee-by-case determination (so long as the opportunity 

for public comment is provided). For convenience, one, many or 

all units at a source could be reviewed'and subjected to public 

notice and comment concurrently with the issuance or renewal of a 

title V operating permit. For units eligible for the "clean . 

- unit" exclusion due to a prior NSR BACT or LAER determination, or 

a determination under a program found comparable by EPA, .the 

title V permit offers the opportunity to clearly set.forth the 

10 While rules implementing .title V address how the unit's 

major NSR permit and BACT or LAER limit are incorporated into the 

title V permit, it is not clear that the status of a unit as a 

NSR clean unit would be included in the title V permit as an 

applicable requirement. Whether the status of a unit as a NSR 

clean unit presumption is an applicable requirement in the title 

V permit will likely depend upon how the clean unit test is 

adopted by the permitting authority (e.g., adopted as a SIP 

requirement). The EPA solicits comment on the best approach'for 

implementing and coordinating the review and designation of clean 

units with the title V permit process. 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

•*** July 5, 1995 [file name.: Master6.29] •** 
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38 H _ • • 

status of the unit under the Clean.Unit exclusion. Qualifying 

clean units and the pollutant for which the determination was . 

made should be clearly identified and listed in the title V 

permit as "clean units" for NSR purposes. 

Under today's proposal, a unit that does not initially 

qualify for the clean unit exclusion could install controls 

meeting.the criteria the EPA establishes for well-controlled.' . 

units and thereby qualify to use the exclusion.•• The controls or 

... . i 

pollution reduction strategy that are the basis for the clean 

• unit determination must be in place and federally enforceable at 

the time•the source relies on an exclusion under this provision. 

' So long as these federally'enforceable conditions are met, the 

source is free to make any change at the permitted unit including 

those which could affect a unit's efficiency, capacity,. 

availability, longevity and utilization. However, changes which 

would'bring into question the original emissions unit•s BACT or 

LAER control level or air quality impact (e.g., modified stack 

parameters which would cause or contribute to violation of any 

applicable ambient standard, replacement of the unit with a• 

different type or size of unit, or reconstruction of the unit) 

would not be allowed. Also, for units excluded from major NSR 

/under this proposed revision, the physical or operational change 

•: must still comply with all otherwise applicable Clean Air Act and 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA FOLICY 

*'** July 5, 1995 [file name: Master6.29] *** 
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1 

"? 

•39 

SIP requirements including any federally enforceable limits on 

emissions or operations and minor NSR requirements.-

Finally, the .determination that a unit is "clean" or "wellcontrolled" under today's proposal is independent from the caseby-case determination of BACT or LAER for sources subj'ect to 

major NSR. While control technology which qualifies a unit'^ as ' 

".clean" may be comparable to BACT or LAER, it is not necessarily 

equal to'BACT or LAER, and in no way establishes a presumptive 

BACT or LAER. Further, a five .or ten year presumption that a 

unit is "clean" does not in any way "freeze" BACT or LAER 

determinations in permitting actions. The Act requires that BACT 

and LAER be current case-by-case determinations for sources 

subject to major NSR and the clean unit test cannot override this 

requirement. 

4. Description of the Clean Facility Proposal. 

Similar to the clean unit exclusion, EPA is proposing, an 

exclusion for changes at clean facilities. This "clean' facility" 

exclusion will allow States to exclude from major NSR proposed rLt 

%* t •" 

changes to an existing major stationary source that has installed AP^Hjk' 

major BACT or LAER and has undergone an air quality impact \ 

analysis as appropriate tq the area designation/ or which 

otherwise qualify as a "clean facility." See proposed sections 

5l'.165(a) (1) (y) (C) (11) , 51.166(b) (2) (iii) (M) and 

52.21(b) (2) (iii) (M) . Under this exclusion, sources can make any 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

*** July 5, 1995 [file name: Mastar6.29] *** 

M. 
P.16 

40 • 

change to the major stationary source that is consistent with the 

PSD or NSR permit. The EPA envisions this to allow changes that 

do not include adding new units or allowing emissions trades that 

were not evaluated for air quality impacts in the NSR or PSD 

permit. The exclusion would, allow, however,; source to"replace or 

reconstruct existing units so long as they continue to meet the 

control technology and emissions requirements established in the 

. permit. Thus, such replacement or reconstruction would not 

result in a different type of unit than envisioned and covered by 

the PSD or NSR permit and its requirements.. 

The EPA- requests comments on this proposal and whether the 

determination of "clean" facility should be more stringent or 

similar to the "clean" unit. The EPA is proposing that the 

qualification for this exclusion.be similar to that under the ' 

clean unit exclusion. As proposed, a clean major stationary 

source is one that underwent NSR within the last 10 years. EPA 

also requests comment on whether this proposal should not allow 

units or facilities to be replaced or reconstructed. Certainly,' 

adding new units would not be permitted under the. proposal 

becau.se such changes would hot be consistent with the existing 

NSR permit. Similarly, emissions -trades may not be permissible 

where an different air quality' impact would result since the .PSD 

or NSR permit might limit such differing impacts. 

D. Revision to the Netting Baseline , 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

• BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

'•*'* July 5, 1995 [filename: Master6.29] *** 
P.17 

Wouldyou 

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P.18 

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units that already/have state-of--the-art emission controlsj In 

'general, this new "clean unit" exclusion will allow States to 

exclude from major NSR, proposed changes.to existing emissions 

units that have installed major BACT or LAERAor which otherwise, 

qualify as a "clean unit." Under this exclusion, sources can 

make any change to a qualifying unit so long as the change will, 

not increase the unit's emissions rate (measured in terms of the 

unit's maximum hourly emissions, the new source performance 

standard (NSPS) test found at.existing 40 CFR 60.14). 

Specifically,, changes which do not .increase the unit's hourly 

potential emissions would not be considered a physical or 

operational change and thus would not trigger major NSR.9 .'See 

proposed sections 51.165(a)(1)(v)(C)(1£), 51.166(b)(2)(iii)(L) 

and 52.21(b) (2) (iii) (L) . The proposed "clean unit" exclusion 

9 Under today's proposal, for units that are permitted to 

change feedstocks frequently, such as pharmaceutical 

manufacturing and certain chemical batch processes, the maximum 

hourly emissions rate test would be applied on a per feedstock 

basis to determine if an emission increase will occur. For 

example,- a unit which has state-of-the-art VOC control technology 

and uses toluene and other organic solvents as feedstocks, the 

hourly maximum emission rate.of toluene before and after the 

proposed physical or operational change would be assessed as if 

toluene alone was to be fully utilized by the unit before and. 

after the proposed change. The other feedstocks would alsq be 

individually assessed. A change in feedstock would not trigger 

NSR if the control technology designed to control, emissions 

resulting from the"feedstock and the unit was previously 

permitted to use the feedstock. The EPA encourages suggesti6ns 

in developing rules or guidance on other approaches .for . . 

.determining emissions increases for processes with rapidly 

changing and mixed feedstocks. 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

*** July 5, 1995 [file name: Master6.29] *** 

3//*^ 
P.19 

.30 

would both simplify the applicability test for qualifying units 

and increase source flexibility- It would also reward sources 

that have applied (stringenp controls to their emissions .units. 

Ideally, the change in.hourly potential emissions would be 

assessed immediately before and after the change to. determine if 

an emissions Increase did indeed occur. However, this may not be 

practical in many instances because information necessary to 

establish the hourly potential emissions rate may require 

considerable time to develop or collect. Therefore, under the 

proposed provision, the pre-change.hourly potential emission rate 

may be established or verified at any time up tb 6 months prior 

to the proposed activity or project. The EPA solicits comment on 

alternative periods for establishing the pre-change hourly 

emissions rate, particularly periods which might allow the use of 

routine compliance emissions tests to determine the emissions 

rata (e.g., annual). Also under the proposed provision, where 

the unit is subject to a federally enforceable limit on 

operations or emissions which'limits the unit's hourly potential 

emissions tc less than the maximum, physically achievable hourly 

rate,:the unit's lower allowable rate, must be used in determining 

if an amissions increase will occur at the unit." 

. 1, T-Jhat Constitutes a "-Clean Unit" 

For chis exclusion to function, it is necessary to . 

distinguish a well-controlled unit from a poorly controlled one. 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND . 

BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

*** July 5, 1995 --- [file name: Master6.29) *** 

fH 
P.20 

"'31 • • • 

In other words, what criteria distinguish a unit eligible for 

this exclusion from one which is not? Criteria which allow a 

broad-range of units to qualify could largely transform the 

existing applicability system into one based solely on assessing 

a unit's potential emissions, with the possibility of a dramatic 

increase in a unit's actual emissions without undergoing NSR. 

The EPA's proposes.to require emissions units to have a v 

"federally enforceable emissions limit" that "is comparable, to J<ty ^" 

the -emission limit that . . .would result from 'a current- review.". 0? VC * 

under the BACT or LAER requirements, whichever Is applicable to \ ^ 

the proposed change. (See, e.g.. proposed sections r% 

51.165(a) (1) (v) (C)(i£) (ii),, 51.166 (b)(2) (iii) (D.(2) and " • 

52.21(b) (2). (iii) (L) (2) .) The EPA envisions that three types of 

limits would qualify: (1) BACT or LAER limits set within the^last 

10 years^ (2)qlimitya7setAby a Stat** t^ff"

nr>1 ftffY y^view program . 

determiro-j ^Y B p & +'n h p equivalent to the federal BACT or LAER 

programs;, and OKlimitffiffound on a case-by-case basis -- after 

notice andbpportunity for public comment- -»- to be equivalent tb^*-2-

BACT oi: LAER limit/fiT i \ ^0V\A o&er^sz, \)*eL>»f&£eA ©rv -H-.^. pacfcicuUr 

•"T ,i ."~ .... „*_-/ T>TaT5 T, ;' un't-fc a-P4rey> uJeCflkV.^ refero-pit cos4; 

a. Units with BACT. or LAER Limits , r-\ 0- - vj 

One starting point for. determining whether a unit is wellcontrolled is the level of control.required tb satisfy BACT (in 

' attainment/tinclassif ied areas) or LAER (in nonattainment areas) . 

• For units which have recently undergone these reviews, rePRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

'•.'•• BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

*** July 5, 1995 --- [file name: MasterS.29] *** 

n i f 
r P.21 

. . .• 34 . 

with Federal MACT or RACT limits, the EPA is not inclined to do • 

so across the board. Rather,' the EPA believes that MACT or RACT 

limits should be found to qualify for the Clean Unit exclusion 

using the case-by-case option described in section•'II.C.3.c 

. below. ".'..'"*•"• • 

b. State Technology Programs Equivalent to BACT or LAER, 

There are many emissions units at stationary sources that 

were permitted according to a State's minor NSR permitting 

program. While these units are. not controlled pursuant to a BACT 

or LAER limit, they still may have state-of-the-art'controls. 

For instance, several jurisdictions have control technology 

reviews as part of State, local or tribal minor NSR program which 

requires new or modifying sources to meet emissions levels 

equivalent to major source control technology requirements.(BACT 

or LAER) . For this reason-, the EPA is proposing that permitting 

authorities may submit minor NSR control technology requirements 

for certification by the EPA that the minor NSR program requires 

control technology that would satisfy the requirements for the 

clean unit exclusion. See proposed sections 

51.165(a) (1) (v) (C) (Ui) (x) (1) , 51.166(b) (2) (iii) (L) (5J Ui) and 

52.21(b) (2) (iii) (L) (£) (ii) . Once determined by EPA to be. 

equivalent, all units subject to emissions limitation established 

under,the jurisdiction's minor NSR program would be eligible for 

the Clean Unit exclusion for the first 10 years following 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

•** July 5, 1995 --- [file name: Master6.29] *** 

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P.22 

Specifically, an exisiting unit which has not undergone a BACT or LAER dertermination or State 

equivelent process can also qualify as a "clean unit" if, in the informed judgement of the 

permitting agency, a current BACT or LAER determination for the unit would not be expected 

to result in any lower level of emissions from the unit for the pollutant in question. The costs, 

benifits and technical consideration associated with the retrofit application of additional controls 

to the particualr unit may be considered by the permitting agency in the evaluation. -s> .j- . 

\J°~ ^^ 

t/11/ 
P.23 

" - 3 5 • ••.••'" ' 

issuance of the permit. The' EPA also solicits comment on whether 

a shorter period, such as 5 year6, would be more appropriate. 

The EPA also solicits comment bn the appropriate' standards 

for EPA to use'in determining.whether a permitting authority's 

minor NSR program control.technology requirements are comparable 

to the BACT and LAER requirements. The EPA envisions that as a' 

minimum a ',pre--certified" minor NSR program comply with 40 CFR 

51.160-164. 

c. Qualification of Units on a Case-By-Case Basis 

.In many cases an emissions unit not subject to major NSR is 

constructed.or retrofitted with a control technology or strategy 

equivalent to the best controls applied in practice. Thia may 

occur when a source minimizes emissions in order to "net" a unit 

out of major NSR or applies controls to comply with other 

provisions of the Act. For this reason, the EPA's proposed 

regulations would allow a source having a limit .as. sn ,emiB'siorw_-_ 

*r9r \h.t* p«M"t"- t**.\«.r w.n,x 

unit determined to be equivalent to BACT or LAEtPfco quality tor /co*si*teM-

$ 

the "clean unit " exclusion on a case-by-case basis^f Once a cps>\r «.w4' 

b£*e-£-"hs permitting authority makes this determination through a process 

involving notice and opportunity for public comment, the.unit 

would be eligible for the clean unit exclusion for the\next five 

years.. As with the other types of proposed clean unit 

exclusions, EPA requests public comments on the proposed 

'Tn-sect' *jeL& 

exclusion eligibility period. S&&. proposed sections * jjj ^_ i 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

*** July 5,-1995 --- [file name: Master6.29] ••• 

if' A/ 
P.24 

er\ 

Jroposesjaeveral^alternative bases upon which a — ' A dkfr*a.r- . 

.. ' . 36 • a 

51.165 (a) (1) (v) (C) (lfi) (v) (1), 51.166 (b) (2) (iii) (L) (£) (iii) and 

52.21(b) (2) (iii) (L) (£) (iii) . r 

The EP. 

permitting authority could take to make the determination that a 

unit has an equivalent BACT or LAER emissions limit at i5n. The 

first would be based on an average of BACT or LAER for equivalent 

or similar sources over a recent period of time (e.g., most 

recent three years) . The second would be based on the unit'.s 

control level being within some percentage (e.g., five or. ten 

percent) of the most recent, or average of the most recent, BA' 

or LAER levels .for equivalent or similar sources.. The EPA 

solicits comment on these approaches and on the general issues 

concerning whether and how.EPA should impose a.specific . 

methodology for determining that a specific emissions limit 

r^H -fcUxV \Aovlc**. rest--

"comparable" to the (current)BACT or LAER limit^ ^ ^ ^ cltf ^ ^\ ^ \ 

For all of the above tests, the EPA realizes that, there are 

many source and emission unit categories for which BACT pr LAER 

determinations do not exist, let alone recent determinations. 

For. these sources, the EPA proposes that their level of control 

be gauged against the control level associated with BACT or LAER 

for amission unitPciiFFTcirTou s with similar-emissio r • ~n : stream characteristics .- — . 

That is, if the emissions unit were to undergo a BACT or LAER 

A •. • . • 

review today or recently, what technologies would be evaluated 

and what are the^current)BACT or LAER levels associated with; 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

*** July 5, 1995 [file name.: Master6.29] *** 

% / -
P.25 

f^HouS-S v\eu}; Use r 

T^VX" ©k £Cs.q&3S~ 

37 

those technologies? / Since thia in effect requires the permitting 

authority to engage in a BACT or LAER review in order to qualify 

a unit for thia exclusion, the EPA is asking for comment on other 

approaches for qualifying unit6 

States are encouraged to use the permitting process, required 

by title'V of the Act as the vehicle for determining and 

recording which units at a title V source can qualify for this 

exclusion.10 . The permitting authority could use the title V 

permit issuance,, revision or renewal process as the mechanism for 

making the caee-by-case determination (so long as the opportunity 

for public comment is provided). For convenience, one, many or 

all units at a source could be reviewed'and subjected to public 

notice and comment concurrently with the issuance or renewal of a 

title V operating permit. For units eligible for the "clean, 

unit" exclusion due to a prior NSR BACT or LAER determination, or 

a determination under a program found comparable by EPA, .the 

title V permit offers the opportunity to clearly set.forth the 

10 While rules implementing .title V address how the unit's 

major NSR permit and BACT or LAER limit are incorporated into the 

title V permit, it is not clear that the status of a unit ae a 

NSR. clean unit would be included.in the title V permit as an 

applicable, requirement. Whether the status of a unit as a NSR . 

clean unit presumption is an applicable requirement in the title 

V permit will likely depend upon how the clean unit test is 

adopted by the permitting authority .(e.g., adopted as' a SIP 

requirement). The EPA solicits comment on the best approach'for 

implementing and coprdinating the review and designation of clean 

units with the title V permit process. 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

: BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

•*** July.5, 1995 [file name. Maater6.29] *** 

\0(n/ 
P.26 

• 38 , ' 

t 

status of the unit under the Clean.Unit exclusion. Qualifying 

clean units and the pollutant for which the determination was . 

'made should be clearly identified and listed in the title V 

permit as "clean units" for NSR purposes. • . •*(£?. 

Under today's proposal, a unit that does not initially . \ 

-At-H .qualify for the clean unit exclusion could install controls 

meeting the criteria the EPA establishes for well-controlled Mc. 

units and thereby qualify to use the exclusion.•• The controls o^ ^-^H 

W c/ pollution reduction strategy that are the basis for the clean / ^X4- \£-

/ o&fl • V 

unit determination must be in place and federally enforceable at 7 ' ,CV 

the time•the source relies on an exclusion under this provision, {* '•ft 

' So long as these federally'enforceable conditions are met, the gpHu 

source is free to make any change at the permitted unit including w. 

those which could affect a unit's efficiency, capacity,. y J ^ J 

' •' tf F 

availability, longevity and utilization. However, changes which \°^i-

• • f? '•.' .. 

would bring into question the original emissions unit's B^CT or Q, 

LAER control level or air quality impact (e.g., modified stack 

parameters which would cause or contribute to violation of any 

applicable ambient standard, replacement of the unit with a 

different type or size of unit, or reconstruction of the unit) 

would not be allowed. Also, for units excluded from major NSR 

.'under this proposed revision, the physical or operational change 

.. must stir.l cbmply with all otherwise applicable Clean Air Act and 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AND 

BUDGET REVIEW * DOES NOT REPRESENT OFFICIAL EPA POLICY 

*** July 5, 1995 [file name! Master6.29] *** 

: • w . IV 
P.27 

" -39 : ~" 

S IP requirement*, including any federally enforceable limits on 

emissions or operations and minor NSR requirements.. 

Finally, the determination that a unit is "clean" ot "wellcontrolled" under today's proposal is independent from the caseby-case determination of BACT or LAER for sources subject to 

major NSR. While control technology which qualifies a unit', aa ' 

".clean" ma y be comparable to BACT or LAER, it is not necessarily- < 

—for-Bwc-fc Uin.lt t\S a. ^et J 4 w*..*t ' >• cii-ci^s+^C^ S 

equal to BACT o r LAER. and in no way establishes a presumptive 

•for -t^o-A: **-*>•.~t, s«*w.r^ . -jjyfC or <zxJct.s»ry ^^^_ ^ .-' 

BACT or LAER. Further, a five .or ten year presumption that a j 

unit is "clean" does not in any way "freeze" BACT 6r LAER 

determinations in permitting actions. The Act requires that BAC T 

a nd LAER be current case-by-case determinations for sources 

subject to major MSR and the clean unit .t-efc. cannot override this 

geejuia? ementrt 

4. Description of the Clean Facility Proposal. 

Similar to the clean unit exclusion, EPA is proposing an 

exclusion for changes at clean facilities. This "clean' facility" . 

exclusion will allow States to exclude from major NSR proposed •/D *^A 

%e't^ 

changes to an exlating major atationary aource that haa inatalled 0p* .As * 

major BACT or LAER and haa undergone an air quality impact 

analysis as appropriate tq the area designation," or which • ' y X ' 

otherwise qualify aa a "clean facility." See proposed sections i©^ ^f*\ 

51.165(a) (1) (v) (C) (il), 51.166(b) (2) (iii) (M). and ••• ^ „V>.,1. 

52.21(b)(2)(iii)(M). Under this exclusion, sources can make anyipt dju 

••'••• • ' • v^ x 

PRELIMINARY STAFF WORKING DRAFT FOR OFFICE OF MANAGEMENT AN D X H V^ * 

BUDGET REVIEW. * DOES NOT REPRESENT OFFICIAL EPA POLICY ^\0(^ 

•** July 5, 1995 --- [file name: Mas ter 6.2 9] *** • ' ^jb^ 

C« 

[V