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Citation: 58 Fed. Reg. 31622 1993

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ENVIRONMENTAL PROTECTION
AGENCY

40 CFR Parts 51 and 52 [AD-FRL--4658-4]

Prevention of SignificantDeterioration for Particulate Matter
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.

SUMMARY: The EPA is revising the maximum allowable increases (increments) for particulate matter (PM) under the requirements for prevention ofsignificant deterioration (PSD) of air quality. The revised increments, based

on particles with an aerodynamic diameter of less than or equal to a nominal 10 micrometers (PM-10), replace the original increments for PM, which were based on total suspended particulate (TSP). As a result, the PSD increments and the national ambient air quality standards (NAAQS) for PM will be measured by the same indicator for PM, namely PM-10.

This action is authorized by the Clean Air Act (Act) and fulfillsEPA's obligations arising out of a consent decree entered on April 19, 1990. DATES: Effective: June 3, 1994.

Under section 307(b)(1) of the Act, petitions forjudicial review mustbe filed on orbefore July 6, 1993 in the U.S. Court of Appeals for the DCCircuit. ADDRESSES: Supporting information used in developing this rule is contained in Docket No. A-88-19. This docket is available for public inspection and copying between 8:30 a.m. and 3:30
p.m., Monday through Friday, atEPA's Central Docket Section (LE-131), room M-1500, Waterside Mall, 401 M Street SW., Washington, DC 20460. A reasonable fee may be charged for copying.

FOR FURTHER INFORMATION CONTACT: Dan deRoeck, Air Quality Management Division (MD-15), Office ofAir Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, (919) 541-5593.

SUPPLEMENTARY INFORMATION: The
contents oftoday's preamble are in the following format:
I.Introduction II.

Background A.The PSD Program B.

Proposal ofPM10 Increments C.

The 1990 Amendments Ill. Discussion ofFinal Rule and Comments

A.Legal Authority 1.Background 2.Public Comments 3.Decision and Response to Comments B.Selection ofthe Equivalence Approach 1. Background 2. PublicComments 3. Decision and Response to Comments C.Development ofEquivalent Numerical

Levels 1.Background 2. Public Comments 3. Decision and Response to Comments D. Implementation Issues 1.Source Applicability 2.Geographic Applicability 3.Retention ofTSP Baseline Dates and

Baseline Areas 4.Implementation Date 5. Grandfathering Provisions 6.Exclusions From Increments

Consumption 7.Prevention ofSignificant Deterioration

Monitoring 8. Area Source Impacts E.Other Issues 1.TSP Area Designations 2.Regulatory Impact Analysis IV.Administrative Requirements

A. Reference Documents B.Executive Order (E.O.) 12291 C.Paperwork Reduction Act D. Economic Impact Assessment E. Regulatory Flexibility Act Certification F.Effective Date

I. Introduction

The EPA is today adopting final rules which revise the PSD requirements for PM. The revisions affect the regulations in 40 CFR parts 51 and 52 which specify the incrementsforPM. These increments apply to actual emissions changes which occur after the baseline date in areas which have attained the national ambient air quality standards (NAAQS) for PM.

Increments for PM were originally set forth in the Clean Air Act Amendments of1977 (1977 Amendments). The original increments were specified in

terms ofambient concentrations ofTSP, which was the form ofPM addressed in the NAAQS at that time. The revised increments for PM, measured as PM-10, restrict increases in ambient concentrations ofPM-10 to the following levels: 4 g/m 3 (annual arithmetic mean) and 8 V/M 3 (24-hour maximum) for Class I areas, 17 g/m 3 (annual arithmetic mean) and 30 gim3
(24-hour maximum) for Class II areas, and 34 g/m 3 (annual arithmetic mean) and 60 g/m 3 (24-hour maximum) for Class ITT areas. The implementation ofthe new PM10 increments will utilize the existing baseline dates and baseline areas for PM. As such, PM increments, measured

asPM-10, already consumed since the original baseline dates established for TSP will continue to be accounted for, but all future calculations ofthe amount ofincrements consumed will bebased

on PM-10 emissions beginning on the implementation date ofthe new PM-10 increments. The implementation date will vary depending on the State implementation plan (SIP) approval
status ofthe applicable PSD program. For the Federal PSD program, the implementation date is 1year from today. ForEPA-approved State PSD
programs, the implementation date is the date upon which a particular State's revised program, containing the new PM-10 increments, is approved by EPA.

Today's preamble discusses the background ofthe PSD program and the relevant 1990 Amendments, and includes a discussion ofthe significant public comments EPA received on the proposed rule, as well asEPA's
responses to these comments.

II. Background

A. ThePSD Program

Although the Clean AirAct Amendments of1970 provided a scheme to address emissions in areas of the country where pollution levels exceeded the NAAQS, the Act atthat point contained no explicit provision addressing potential deterioration of ambient air quality in those areas where pollutant levels werebelow the NAAQS. In 1972, the Sierra Club brought suit alleging that the Act required State plans to include

measures to prevent the "significant deterioration" ofthe air in parts of the country already in compliance with the NAAQS. The court held that theAct, by declaring the legislative "purpose of protecting and enhancing" air quality [section 101(b)(1)), mandated thatEPA require States to protectthe air quality ofclean areas from significant deterioration. IIn response to this decision, EPA promulgated PSD regulations in 1974.

In 1977, Congress consolidated and expanded EPA's original PSD program by adding a statutory PSD program at part C oftitle Iofthe Act, (sections 160- 169). 2 Under these provisions, States with areas that are in compliance with the NAAQS are required to adopt a permit program for the preconstruction review ofnew stationary sources and modifications ofexisting stationary

sources to prevent significant

ISee Sierra Club v. Ruckelshous,344 F.Supp. 253, 256 (D.D.C. 1972), affdpercurium, 4 ERC 1815 (D.C.Cir. 1972)oaff dbyan equallydivided court, sub. nom Fri v. Sierra Club,412 U.S. 541 (1973).

2 All section references areto the Act unless noted (sections 100-183,42 U.S.C. 7401-7671q). Part C alsoincludes a subpart which provides for the protection ofvisibility in certain national parks, wilderness areas and other so-called "mandatory Class I Federal areas" (see section 169B).Federal Register / Vol. 58, No. 105 / Thursday, June 3, 1993 / Rules and Regulations

deterioration ofexisting air quality levels. 3

The PSDprogram mandated by Congress isrequired to balance three primary goals, as specified by section 160 ofthe Act. The first ofthese goals is to protectpublic health and welfare from actual orpotential endangerment. This goal includesthe protection of existing air quality in all areaswhere the ambient pollutant concentrations required by the NAAQS are currently being achieved. The second goal emphasizes the protection ofair quality in national parks, wilderness areas, and similar areas ofspecial concern where air quality is considered particularly important. The third goal is to assure that economic growth in clean air areas
occurs only after careful deliberation of the impacts ofgrowth on air qualityby the State and local communities, and only when such growth would be consistent with the preservation ofclean air resources.

The PSDprogram in part Cis implemented largely through a control technology requirement and an air quality protection requirement. The control technology requirement, contained in section 165, requires that major new and modified stationary

sources ofairpollution use best available control technology (BACT)in order to minimize pollution from these

sources. The BACT mechanism is intended to result inthe adoption of state-of-the-art pollution controls over time, as the existing capital stock of pollution generating equipment generally wears out and is ultimately replaced. The BACT requirement reflects several policyjudgments by Congress. First, minimizing pollution from new and modified stationary

sources serves the statutorygoals of protection and enhancement ofair quality and pollution prevention [sections 101(b)(1), 101(c) and 1601. Second, air quality protection mechanisms are imperfect and may not, standing alone, fulfill all ofthe goals of the PSD program. Third, the effective reduction ofpollution from any single

new or modified stationary source will increase opportunities for additional growth within the constraints ofthe air quality protection requirements ofthe PSD program.

3The PSD requirements apply to areas classified pursuantto section 107 ofthe Act as attainment or unclassifiable. Forpollutants for which no NAAQS have been promulgated,and forpollutants not subject to thesection 107 area designation process. the PSD requirements apply everywhere as long as
an area Is designated asattainmentorunclassifiable for at least one pollutant for which NAAQS do exist (i.e.. forat least one criteriapollutant). The principal air quality protection mechanism under the PSD program involves a system of"increments" and

area classifications that effectively define "significant deterioration" for individual pollutants.4In Section 163 of the Act, Congress initially defined statutory numerical increments forPM and sulfur dioxide (SO 2 ) asthe maximum permissible increases, above baseline levels, in the ambient concentration ofthe pollutants in a PSD

area. Congress determined that the PM increments levels it adopted provide for both protection ofair quality and (in conjunction with the BACT requirement) reasonable industrial and economic expansion in PSD areas,

The Act divides PSD areas into three classes and applies increments of different stringency to each class. Congress designated areas of special national concern, where the need to prevent significant deterioration in air quality is greatest, asClass Iareas. Consequently, the most restrictive increments apply in this class. Section 162(a) ofthe Act established "mandatory" ClassI areas,which include all international parks aswell as national parks, national wilderness

areas, and national memorial parks exceeding certain sizes and existing on the effective date ofthe 1977 Amendments.5 These Class I areas are termed "mandatory" because Section 162(a)also prohibits the States (or inthe

case ofIndian lands, Indian tribes) or EPA from redesignating these mandatory Class I areasto any less protective classification.

Less restrictive increments apply in

areas designated as Class Hor Class III. Initially, Congress classified as Class 11

areas all attainment and unclassifiable

areas that were not classified as Class I

areas. Section 164 ofthe Act allows that Class IIareas may be redesignated by the States to Class IorClass III under certain circumstances. The Class I area designation allows States (orIndian tribes) to permit more deterioration in air quality in specific areaswhich States
may target for higher levels ofindustrial development and consequent growth in

4The increments forPM enacted byCongress in 1977 and listed in163 were based on the NAAQS forPM. which, untilJuly 1,1987, used TSP as the unit ofmeasurement (indicator) forambient PM concentrations.

3Under the 1990 Amendments. Congress enacted

new language which affects theboundaries ofthe mandatory Class Iareas Section 162(aX4) now stipulates thattheboundaries ofmandatoryClass I

areasmust conform to any changes occurring since the date oftheiroriginal classification in 1977. Previously, theboundaries were retained atthe 1977 parametersunless specific boundary changes

were made underthe statutoryredesignation proceduresunder 1164 oftheAct. pollution. To date, no State or Indian tribehas elected to establish any Class III areas.

The EPA implements the statutory PSD requirements through two sets of regulations. At 40 CFR 51.166, EPA has
setminimum program requirements for States to follow in Rreparing, adopting, and submitting a P9Dprogram for inclusion as part ofthe required SIP pursuant to Section 110(c) of theAct. At 40 CFR52.21, EPA has promulgated a Federal PSD program requiring the Administrator's preconstruction review and approval of major new or modified stationary sources in the absence ofan approved State PSD program, and for

areas such as Indian Lands and Outer Continental Shelfareas that are outside ofthejurisdiction ofindividual States.

B.Proposal ofPM-lOIncrements

On July 1, 1987, the EPA revised the NAAQS for PM to replace the TSP indicator with the PM-10 indicator (52 FR 24634). Inthe same Federal Register, EPA adopted various final regulations to implement the revised standards. These regulations, in part, added PM-10 to the PSDregulations to reflect its status as a newly-regulated form ofPM. Consequently, PM-10 emissions became subject to consideration forapplying BACT, for conducting preconstruction ambient monitoring, and for dispersion modeling to demonstrate that proposed

new and modified PSD sources will not

cause or contribute to any violation of the PM-10 NAAQS. However, at that time TSPremained the ambient Indicator ofPM for determining the
amount ofsignificant deterioration ofair quality.

On October 5, 1989, EPA proposed to revise the existing PM increments, based on TSP, by promulgating replacement increments based on PM10 (54 FR 41218, October 1989). The proposed PM-10 increments were intended to be substantially equivalent
to the existing TSP increments. The EPA issued its proposal under the authority ofSection 166(a) ofthe Actwhich provides that "[in the case ofpollutants which NAAQS are promulgated after the date ofenactment ofthis part, [the Administrator] shallpromulgate such regulations [toprevent significant deterioration ofair quality]." Thus, EPA determined that with the promulgation ofthe NAAQS for PM using the new PM-10 indicator, ithad authority under Section 166 ofthe Actto promulgate

new PM increments also measured in
terms ofPM-10.

C. The 1990 Amendments

A new Section 166(f)to partCofthe Act specifically authorizes EPA to 3162331624 Federal Register / Vol. 58, No. 105 / Thursday, June 3, 1993 / Rules and Regulations

substitute, for the maximum allowable increases in PM specified in Section 163(b) and Section 165(d)(2)(C)(iv), maximum allowable increases in PM with an aerodynamic diameter smaller than or equal to 10 micrometers.

In making such substitution, the amended statute requires that the PM10 increments "shall be ofequal stringency in effect" as the TSP increments which they replace. Moreover, new Section 166(f)requires that the current TSP increments remain in effect until the new PM-10 increments are promulgated. 6

The 1990 Amendments also included provisions which for the first time required the States or EPA to designate all areas relative to their PM-10 attainment status. Pursuant to revised Section 107(d) ofthe amended Act, certain areas were designated by operation oflaw as nonattainment, effective upon enactment ofthe 1990 Amendments, and all other areas were initially designated as unclassifiable. Areas may subsequently be redesignated

to a more appropriate attainment status in accordance with the procedures under the amended Act. Consequently, when States revise their SIP's to incorporate the PM-10 increments adopted today, the PM-10 increments will apply in all areas ddsignated as attainment or unclassifiable for PM-10, but will not apply in areas designated nonattainment for PM-10. Rather, the nonattainment area new source review requirements ofpart D of title I ofthe Act are applicable to major new and modified stationary sources located in such areas. 7

6While the statutory provision stipulates that the existing TSP increments remain in effect at least until the newPM-10 increments are promulgated, it isEPA's intent to require that the TSP increments remain in effect until thePM-10 increments are actually in place as substitutes for the TSP increments in the applicable Federal or State PSD regulations. In that way, the implementation ofthe PSD program forPM will continue without interruption while theindicator used to measure increment consumption switches from TSP to PM10.

'The 1990 Amendments also added Section 189(e), which addresses requirements for major

sources ofPM-10 precursors in PM-10 nonattainment areas. Section 189(e) states: "The control requirements * * for majorstationary

sources ofPM-10 shall also apply to major sources ofPM-10 precursors, except where the Administrator determines that such sources do not contribute significantly to PM-10 levels which exceed the standard in the area." The EPA issued initial guidance regarding thetreatment ofPM-10
precursors in the General Preamble (see 57 FR 13498, atp. 13541, April 18 1992). Additional guidance will be provided in a forthcoming notice ofproposed rulemaking to incorporate NSR
program changes required under the 1990 Amendments. The 1990 Amendments contained no requirement that PM-10 precursors be reviewed as PM-10 under the PSD program. Today's action does
not address this issuefurther; III. Discussion ofFinal Rule and Comments

A. LegalAuthority

1. Background

In the 1977 Amendments, Congress

set numerical PSD increments in Section 163 for both PM and SO2. In establishing the PSD increments for these two pollutants, Congress used the then-existing NAAQS for each pollutant

as the benchmark for determining what constitutes "significant deterioration." Although Section 163 does not expressly define the PM increments in

terms ofa specific indicator, EPA reasoned that Congress' knowledge that TSP was the indicator for thePM NAAQS, and that the TSP standards

were the starting point for the increments levels when the increments

were established in 1977, meant that TSP was also the appropriate measure for the PM increments in Section 163. As a consequence, EPA concluded that the statutory PM increments could not simply be administratively redefined as PM-10 increments, retaining the same numerical values, following the revision ofthe PM NAAQS. Rather, EPA decided that it must promulgate new PM increments, reflecting an equivalent

amount ofair quality protection but expressed in terms of the new PM-10 indicator.8

In the proposal, EPA took the position that Section 166(a) ofthe Act granted EPA the authority to substitute appropriate PM-10 increments for the existing TSP increments. As cited previously, Section 166(a) authorizes EPA to promulgate new increments following promulgation ofNAAQS for that pollutant. Thus, since EPA promulgated NAAQS based on a new ambient indicator, EPA reasoned that the requirements of Section 166(a) gave EPA authority to propose the PM-10 increments notwithstanding the

0The decision Notural Resources Defense Coun.

v. EPA. 902 F.2d 962 (DC Cir., 1990) considered the issue ofwhether EPA had the authority to simply change the indicator by which the statutory increments for PM are measured and concluded that it did not. In that case, the Court held that EPA could in fact change the increments toreflect the

new PM-10 indicator.

"Simply changing themeasurement reference from TSP toPM-10 while maintaining the same numbers * * *would dramatically relax thePSD restrictions on particulate matter since the TSP indicator is amuch more inclusive measure of pollutants * * *. Itwould be wholly irrational for Congress to set forth specific numbers ofparticulate

matter increments and yet authorize a choice of indicators which radically alters thenumbers' significance and therefore ultimately how much particulate matter may be emitted. Congress has plainly expressed an intent to allow a certain quantum ofPM emissions, and we must give that
Intent effect" (see 902 F.2d at 978). existence, in the Act itself, of increments based on the TSP indicator.

The EPA considered simply adding the new increments to the existingTSP increments setforth in Section 163 of the Act. However, EPA determined that this would be burdensome and
unnecessary even during atransition period. As a result,EPA proposed to replace the TSP increments withthe PM-10 increments.

2. Public Comments

A few commenters challenged EPA's overall conclusion that the Act as it stood at the time ofthe 1989 proposal allowed EPA to promulgate increments based on the new PM-10 indicator, and phase out use ofthe TSP indicator. For instance, one commenter argued that Section 166 "by its clear terms" applies only to pollutants forwhich EPA establishes a "new" NAAQS. The
commenter concluded that Section 166 could not apply to the PM-10 increments since EPA admitted that the adoption ofPM-10 NAAQS was nothing

more than a "revision" to the existing PM NAAQS measured as TSP. Another commenter, while not disputing EPA's
power to issue PM-10 increments, questioned whether EPA could drop the TSP increments since it amounted to "amend[ing] a statute of theUnited States." However, mostcommenters agreed with EPA's conclusion that the existing statutory scheme allowed for the substitution ofthe PM-10 increments for the TSP increments, although-as will be discussed shortly-many took the view that EPA's
power to create new PM-10 increments

was narrowly circumscribed.

3. Decision and Response to Comments

As discussed, Congress eliminated
any ambiguity regarding the propriety of EPA's 1989 proposal by specifically addressing EPA's authority to promulgate PM-10 increments. It did so by adding Section 166(f) as part ofthe 1990 Amendments. Pursuant to that section, the "Administrator is authorized to substitute" for the increments specified in Section 163(b) and Section 165(d)(2)(C)(iv), increments based on PM-10. The section also states that "[u]ntil the Administrator promulgates regulations under the authority ofthis subsection, the TSP increments shall remain in effect." Thus in the Act, Congress explicitly clarified EPA's authority to promulgate new increments based on the PM-10 indicator. Indeed, through the choice of the term "substitute" and the instruction to retainthe TSP increments until the new Increments are implemented, Congress also clearlyFederal Register / Vol. 58, No. 105 / Thursday, June 3, 1993 / Rules and Regulations

Indicated that EPA need notmaintain a two-increment system for PM. In short, the Act itselfnow contradicts any assertion that EPA is without power to adopt PM-10 increments orthat the TSP increments must be retained.

Based on this grant ofauthority, EPA today ispromulgating new PM-10 increments forClass I,I1, and m areas, and, as described more fully below, Is eliminating from the PSD regulations the existing TSP increments.

B. SelectionoftheEquivalence Approach

1.Background

In its 1989 proposal, EPA described
two approaches for establishing PM-10 increments that, in accordance with section 166(d) ofthe Act, would be "at least as effective asthe increments established in section 163 [of the Act]." These approaches were referred to as (1) the "equivalent to statutory increments" approach and (2) the "percentage of NAAQS" approach. Different sets of numerical increments levels would result from the two approaches.

The "equivalent to statutory increments" approach, described in Section If.C which follows,.uses the existing statutory (TSP) increments as the benchmark forcalculating new PM10 increments, thereby retaining roughly the same limitations on future deterioration ofair quality and economic growth as was allowed under the statutory TSP increments. In using this approach, EPA considered the historical consumption of TSP increments by a sample population of permitted PSD stationary sources. The EPA then determined the PM-10 increments, for each area classification and averaging time, that would provide approximately the same percentage of PM-10 increment consumption, on average, by the same population of

sources.

Alternatively, the "percentage of NAAQS approach" defined amounts of deterioration relative tothe PM-10 NAAQS which bore the same percentage relationship asthe existing TSP increments bore to the TSP NAAQS from which they were derived. Thus, for example, since the statutory Class U increments for TSP were themselves set by Congress as 25 percent ofthe TSP NAAQS, the Class IIincrements forPM10 arecalculated as 25 percent ofthe PM-10 NAAQS.

The EPA believed that the general equivalence ofthe increments resulting from either approach would satisfy the requirements ofsection 166(d) ofthe Act because both sets ofincrements would be expressed asnumerical measures and could be Implemented similarly to the statutory increments which they were to replace. Also, both
sets ofincrements would provide clean

areas ofthe country with protection against significant deterioration ofair quality, assuming that all existing baseline dates andbaseline areas, as established under the TSP increments,

are left in place.

Nevertheless, EPA decided to use the "equivalent to statutory increments" approach based on its beliefthat this approach more closely matched congressional intent in the special case where the new increments for PM are intended not only to prevent significant deterioration in general,but are specifically to replace (ratherthan supplement) the existing section 163 increments forPM. A more detailed
account ofthisrationale can be found in EPA's 1989 proposal (54 FR41221- 41225).
2. Public Comments

While several commenters supported the "equivalent to statutory increments" approach, most commenters supported the "percentage ofNAAQS" approach. Only five commenters favoredthe "equivalent to statutory increments" approach in whole or inpart. A number ofcommenters expresseddissatisfaction with both approaches, and recommended other options instead.

Commenters favoring the "equivalent
to statutory increments" approach agreed that it was appropriate to select increments which directly correlate with the TSP increments that they will replace. Among those supporters, however, were several commenters who expressed concerns about the technical analysis whichEPA used to develop the equivalent numerical levels for the PM10 increments. These particular
comments are addressed in more detail in the following section entitled "Development ofEquivalent Numerical Levels."

Commenters favoring the "percentage ofNAAQS" approach generally reasoned that such an approach would be more consistent with the manner in which past increments were established by both Congress and EPA. That is,the statutory increments (PM and SO2 )and the regulatory increments (nitrogen dioxide) arebased on percentages ofthe appropriate NAAQS concentrations. Two commenters supported the "percentage ofNAAQS" approach because the numerical increments derived from that approach would be specifically designed to address PM-10 air quality deterioration relative to the then-new PM-10NAAQS which were based on EPA's latest findings on harm to health and welfare from PM. One of these commenters further stated that such increments would establish lower permissible increases in ambient PM-10 concentrations. 9

Eight commenters recommended a different approach altogether. Four such
commenters indicated that EPA's best approach was to simply redefine the existing statutory increments for PM in section 163 ofthe Act as PM-10 increments. Within this group were two commenters who favored the "percentage ofNAAQS" approach over the "equivalent to statutory increments" approach, but only as a secondary option. The other two commenters in this group questioned EPA's legal authority to revise the statutory increments in any manner other than to redefine them in terms ofPM-10, without changing their numerical values.

One commenter recommended that EPA not only retain the statutory increments asTSP-based increments, but establish PM-10 increments to supplement those already mandated by Congress. Three commenters expressed

concern that the proposed increments fail to adequately protect against the secondary or welfare effects-especially visibility-of PM. However, each
commenter arrived at a different conclusion asto how to resolve the problem. One ofthe commenters supported the retention ofthe existing increments expressed asTSP concentrations. Another argued that EPA should adopt PM increments based

on an indicator measuring fineparticles (PM-2.5) (i.e., particles with a diameter ofless than 2.5 micrometers]. This
commenter maintained that there is "a large body of scientific evidence which indicates that PM-2.5 would be an appropriate indicator for visibility effects." The third commenter called for further EPA efforts to develop PM-l0 increments which are protective of visibility in Class Iareas.
3. Decision and Response to Comments

The EPA is today promulgating the PM-10 increments based on the ,"equivalentto statutory increments" approach as originally proposed. This decision is largely based on the reasons setforth in EPA's 1989 proposal, and
upon the expression ofcongressional

91t should benoted that for theannual averaging period the "percentage ofNAAQS" approachyields

ower numerical PM-10 increments than does the "equivalent to statutory increments" approach (e.g. Class 11-13 gI/n vs 17 p/m3). However, for the 24- houraveraging period, which tends to bethe more critical period formeasuring pointsource ambient impacts, the formerapproach yields higher nmericalincrements (e.g.. Class U1-37 Idm 3vs 30 p/M'). 3162531626 Federa Register / Vol. 58, No. 105 / Thursday, June 3, 1993 

### / Rules and Regulations

intent contained intheAct under new section 166(f). TheEPA believes that thisnew section establishes a clear directive for EPAto follow the path laid
out by EPA in 1989 forthe development ofequivalent increments forPM measured asPM-la. New section 166(f) specifically calls for PM-10 increments which are "of equal stringency in effect"
to the existing statutory increments for PM. Accordingly, Congress left it to EPA
to determine the appropriate equivalent levels ofPM-10 that would ensure "equal stringency in effect." Arguably, if Congress hadIntended that the new PM-10 increments be based exclusively

on their relationship to the PM-10 NAAQS, then it would have been a straightforward matter forCongress, itself,to replace the existing statutory increments forparticulate matter with PM-10 increments calculated as a percentage ofthe PM-10 NAAQS.

Inresponse to those commenters who stated that the ClassI PM-10 increments should be set atlevels which provide protection against welfare effects and visibility impairment,particularly in Class I areas, EPA agrees only In a general sense. While itis true that Conrss set the Class Iincrements at levels which allow only arelatively small increase inthe ambient concentration ofa pollutant, there is no evidence that Congress adopted increments that would ensure specific levels ofwelfare and visibility protection at each Class Iarea throughout the Nation.For example, the Increments standing alone do not represent an absolute ceiling on air quality, but rather a limit on the amount ofdeterioration In air quality that varies from area to area depending upon the baseline concentration ofpollution for such area.'0 Under this system, based on thePSD increments alone, two areas with significantly different baseline concentrations ofa pollutant (yetboth within the limits ofthe NAAQS), and havingresources that are significantly different in terms oftheir sensitivity to air pollution, could intheory be allowed
to experience the same increase in ambient levels ofpollution. Thus, the Class Iincrements are designed to protect an area from large adverse changes in air quality, but do not provide an absolute pollutant

1 0The Act sets forthadefnition of 'baseline concentration" which iskey to theway in which the increments amimplemanted Isection 169(4)L Basically. the baseline concmtration Isthe ambien concentration ofa pollutantwhich existsatthe time ofthe firstcomplete application fora PSD permit in an attainmemt ares.On such date theapplicable baseline date isestablIshed andthe baseline concentrationis defined fromwhich sipificeA deteriorationofairqualityis henc measured. concentration ceiling that is grounded

. in the airpollution sensitivities ofthe various Class Iareas.

TheAct's main tool for protecting Class Iareas are provisions specifically addressing the protection of"air quality related values" (including visibility)in such areas (see section 165(d) ofthe Act;

see also,e.g., HadsonPower14-Buena Vista,PSD Appeal Nos. 92-3, 92-4 and 92-5 (Remand Order, October 5, 19921. Congress established the concept ofair quality related values to enable the identification and protection ofspecific ecologically-based attributes contained within any particular Class Iarea.

Section 165(d)(2)(C)(ii) provides that

even when a major emitting facility will
not cause or contribute to an increment exceedance, a permit must not beissued if theFederal Land Manager (FLM) demonstrates to the satisfaction ofthe State that the emissions from such facility will have an adverse impact on the air quality-related values (including visibility) ofsuch lands. In contrast, section 165(d)(2)(C)(iii) provides that when a major emitting facility will

cause or contribute to an increment exceedance, the State may issue a permit ifthe owner oroperator demonstrates to the satisfaction ofthe FLM that the emissions will nothave such an adverse impact."

The Act also provides a general degree of welfare protection with the Class I increments by retaining the short-term increments rather than measuring air quality deterioration only

on anannual average basis. Short-term increments were deemed necessary to protect, among otherthings, the environment ofClass I areas against "chronic low levels ofpollution or from repeated short-term peaks ofpollution
at levelsbelow the minimum Federal standards." 12 The EPAbelieves that the levels ofthe 24-hour PM-10 increments for Class Iareas will provide general protection against visibility impairment

IIDuring the floor debate ofSenate bill 252 (S. 252), Senator Muskie indicated that theClass I increments. ascontained in S. 252. wereestablished

.. solely as ameans ofdetermining where the burden of proofshould lie as toadverse impact on air quality values 1 * (Theincremental do not. in any way.establish afinal basis forapproval or disapprovalofapermitapplicaton." Committee on Environmentand Public Works, 95thCong.. 2nd Seas.. A Legislative History ofthe Clan AirAct Amendments of19" (Vol. 3)at 723-726 (1978.

1 2Tib committee reporton the House of Representatives bill2161 (H.R.211) states that "Iellimination ofthe 24-hourand 3-hour standards would substantially underminethe publichealth and welfare protectionsbuilt intothe committee proposaL"Te committee indicatedItsconcrn that the short-termincrements were ofperticular importance forprotectinS visibility in aeas such as the GrandCanyon. Yellowstone and othernational parks end nationalwilderness areas. Legislative History (Vol 4)pp. 353 and 2637. and other welfare-related impacts In the

samemanner as did theTSP increments whichthey replace. However, specific protection ofany given Class Iarea is intended to be provided by the air quality related values as defined for the particular area ofconcern.

In addition, with respect to visibility impairment, EPA notes that Congress adopted, in section 169A, a specific mechanism whose goal is to remedy any existing, and prevent any future. impairment ofvisibility in Class Iareas. Moreover, section 169B, added by the 1990 Amendments, calls upon EPAto

assess the level ofvisibility that will remain following implementation ofthe other provisions ofthe 1990 Amendments, and to decide whether to adopt a "regional haze" program to address the residual impairment. That multi-year program is now underway.

C.Developmentof Equivalent NumericalLevels.

1.Background

In order to develop numerical levels such that the PM-10 increments would be "equivalent to the statutory increments," EPA considered source information contained in an existing

new source review (NSR) data base. From the data base, containing information from over 500 existing PSD/ NSRpermits issued between 1977 and 1984, EPA found 249 permits which provided sufficient information to estimate PM-10 emissions (using available PM-10 emissions factors) and PM-10 increments consumption.

Separate technical analyses were carried outto establish equivalent levels for the Class I and Class HIncrements. In each case, two important steps were involved in the developmental process. First, theTSP levels were converted to equivalent PM-10 levels by comparing the ambientTSP impacts ofall sources in the data base against theirestimated PM-10 impacts, based onthe estimated PM-1PM emissions ratio for each

source. 1 3 Second, the resulting levels of the equivalent PM-10 annual increments were converted from geometric mean values to arithmetic

mean values.These procedures were described In thePM-10 increments proposal notice (54 FR 41218, pp.

13The PMwhich sources emit is comprised of particles having arangeofsizes. ThePM-10/PM emission ratio,which was ofinterest forthis particularrulemaking,reflects the relativeamount ofPM-1O vs. theamount of totalparticulate emitted by asource. Foranygiven source, thePM-IC/PM ratio will dependupon thespecific emission unit(s) end controldevice (and controlefficiency) associated with thatunit.A necessary pertofEPA's analysis, therefor, was the Identificationofthe uniqueemission tmit.control device combinations contained IntheNSR dat base.Federal Register / Vol. 58, No. 105 / Thursday, June 3, 1993 / Rules and Regulations

41223-41225) as well as in atechnical report entitled "Technical Report

- Equivalency ofAlternative PM-10 Increments" (Radian Corp., March 1989), which was made available for public inspection in the docket for this rulemaking action.

In summary, the determination of equivalent Class II PM-10 increments involved the selection ofa PM-10 value from arange of"equivalent" increments by comparing the TSP vs. PM-10 impacts ofeach of the 249 PM sources in the NSR data base. In principle, for
any source, the equivalent PM-10 increment is simply the product ofthe TSP increment and the source's PM-10/ PM emissions ratio. Once the range of "equivalent" PM-10 increments was defined, EPA plotted the amount ofTSP increment consumed along with the
amount ofPM-10 increment consumed (using trial increment levels selected from the defined range of"equivalent" PM-10 increments) on a source cumulative basis (i.e., percent of increment consumed vs. cumulative number ofsources with impacts less than or equal to a specific amount of increment consumption). By plotting the information on a cumulative basis it

was possible for EPA to determine the PM-10 increment level (for each applicable averaging time) that best represented "equivalent effect" in terms of amounts ofTSP and PM-10 increment consumption forthe entire sample PSD source population.

Forthe Class I increments, considerably less source data were available because relatively few major

sources were found to be constructed in the vicinity ofClass I areas. For this

reason, in selecting equivalent Class I increments EPA did not attempt to
compare the percentages ofTSP increments and PM-10 increments on a source-aggregated basis. Instead, EPA directly examined 16 sources in the NSR data base having PM impacts which effect Class I areas.

No specific analysis was performed to develop equivalent Class I increments for PM-10. Instead, Class Ill increments

were determined simply by doubling the levels selected for the Class HPM10 increments, since all ofthe statutory Class I increments are levels which are twice the Class l1 increments levels. 14

The equivalent numerical levels ofthe PM-10 increments initially bore the

same deterministic form as the statutory TSP increments, and were stated as

' 4For example, Congress set the annual Class U Increments for PM at 19 Ag/m 3(25 percentofthe annual PM NAAQS), and theClass U1 increments for PM at 37 pg/m3 (50 percent ofthe annualPM NAAQS). geometric mean values as well.15 In contrast, the PM-10 NAAQS are expressed in a statistical form, with the annual standards stated asarithmetic

mean values. ie In order for the PM-10 increments to be completely consistent with the form ofthe PM-10 NAAQS, it would have been necessary to apply three separate conversion factors. As explained in the proposal notice, EPA elected to make only one conversionthat being to change the annual increments from geometric mean values
to arithmetic mean values (54 FR at 41225). Thus, thePM-10 increments which EPA proposed remained in the deterministic form, but included annual increments expressed as arithmetic

mean values.

2. Public Comments

Nine commenters, including some who supported EPA's "equivalent to statutory increments" approach for selecting equivalent PM-10 increments, expressed both general and specific

concerns about thetechnical analyses and conversion procedures used to establish the equivalent numerical levels.

Several ofthe commenters expressed general concern about the overall adequacy ofthe NSR data base which EPA used to develop source-specific estimates ofPM-10 emissions and PM10 increments impacts. The commenters' concerns focused on both the quantity and quality ofthe information in the data base. One of these commenters questioned the completeness and accuracy ofthe information contained in the individual

ermit applications from which the data

ase was derived. This commenter complained that the use ofonly 249

sources "suggests the possibility of uncertainty and source-specific bias." This commenter also claimed that the ambient TSP impacts contained in the data base were suspect because the air quality dispersion models used by the permit applicants may have been conservative and outdated. Another

"'Theterm "deterministic" describes the method by which attainment ofaparticular standard or Increment is determined. Attainment ofa deterministic standard orincrement considers the number ofexceedances that have occurred, orwill

occur (basedupon modeling predictions), in a single year independently from other years ofdata. For example, a 24-hour deterministic standard would be attained when the standard level is not exceeded more than once in any given calendar
year.

yAttainment ofa statistical standard considers the number ofexceedances that haveoccurred, or will occur (based on modeling), on average over a number ofconsecutive years. For example, a 24- hour statistical standard is attained when the expected number ofexceedances ofthe standard level is. on average, no more than one per year. commenter claimed that the data base is biased because it relies on information which does nottake into account current, more efficient controls which result in higher PM-10/PM emissions ratios (i.e., majority of particulate emissions are PM-10).

The EPA's calculation ofPM-10 emissions for sources in the data base

.wasalso the subject ofseveral
comments. One commenter complained that the EPA relied upon "limited and biased PM-10 data" to develop PM-10 emissions factors. The same commenter further noted that very little data were available on the PM-la portion ofTSP formajor source categories to adequately define the proper PM-IO/ TSP ratios. Another commenter reiterated the concern over the lack of PM-la emissions data and complained that EPA's method "assumed an arbitrary average ofPM-10/PM ratios wherever multiple emission sources

were involved." It was this commenter's conclusion that "[elach individual case may be far different than portrayed, and there is very little certainty that the grand total is correct." Regardless ofthe

means ofcalculating the appropriate PM-10/PM emissions ratios, this
commenter argued that "the EPA equivalent method substantially underestimates equivalent PM-10 increments because it uses PM-10/PM rather than the proper ratio ofPM-10/ TSP."

One commenter went to great lengths
to describe "a basic fallacy" in EPA's technical method, based on the modeling ofPM emissions from sources in the NSR data base, for developing

new PM-10 increments which are equivalent to the existing statutory TSP increments. The basic fallacy, according
to the commenter, is that "TSP does not equal PM." The commenter's claim was based on the fact that the collection efficiency ofthe ambient sampling method forcollecting TSP is significantly different from various instack sampling methods for measuring emissions ofPM. Thus, the commenter argued that "EPA's assumption that TSP and PM are equivalent, which underlies the 'equivalent' increments, is simply incorrect."

Several commenters representing the miningindustry criticized the proposed PM-la increments levels claiming they could lead to severe constraints or complete prohibition of some mining activities.-According to these commenters, "this harsh result is imposed for little environmental benefit, because there is substantial evidence that mining-related fugitive dust, even that smallerthan 10 micrometers, has little orno human health or 3162731628 Federal Register / Vol. 58, No. 105 / Thursday, June 3, 1993 / Rules and Regulations

environmental significance, as compared with the urban pollution upon which the PM-10 NAAQS were based." Faced with these alleged economic consequences, the
commenters urged EPA to adopt a "twotiered" PM-10 increments system, such that the second tier increments would be 50 percent larger than the first-tier (e.g., the proposed increments) and applicable to thearidWestern United States and/or to "specific fugitive dust
sources, such as surface mines."

Finally, one commanter criticized EPA's decision to convert the annual PM-l0 increments from geometric mean to arithmetic mean values but to leave the increments in the deterministic form for compliance determinations. Inthe view ofthis commenter, EPA should
express the annual PM-10 increments

as geometric mean values in order to (1) avoid the greater stringency inherent to the arithmetic mean, and (2) maintain consistency with Congress' approach in section 163. On the other hand, the
commenter recommended that EPA
express the PM-10 increments on a statistical basis rather than the deterministic form which EPA proposed. Noting that the PM-10 NAAQS are already expressed as statistical standards, thecommenter claimed that EPA's proposal would require duplicative and redundant recordkeeping and compliance evaluations, while PM-10 increments expressed in a statistical form would reduce thecost and complexity ofthe compliance analysis.
3.Decision and Response to Comments

The EPA disagrees with those
commenters who claimed that the NSR data base was inadequate for developing the equivalent PM-10 increments. The EPA believes that the NSR data base sample is representative ofthe types of

sources and PM emissions controls that

can be expected to apply forPSD permits and consume PM-10 increments throughout the Nation. The 249 sources from which information on PM wastaken for the equivalency analysis represent 39 different source categories, each with a wide range of emissions types and control technologies. Moreover, EPA finds no

reason to believe that the information contained in the original PSD/NSR applications was either inaccurate or incomplete, nor was any specific deficiency identified by the commenter. The EPA remains unaware ofany better data that could have been used to carry out the analysis.

The factthatthe data base is limited
to permits issued between 1977 and 1984 does notrender theinformation as inadequate for establishing equivalent PM-10 increments. It does not automatically follow, asa few
commenters concluded, that sources with improved control efficiencies (and thereby higher PM-10/PM emissions ratios)will have a more difficulttime complying withthe PM-10 increments promulgated by EPA. Improved control efficiencies serve not only to increase the PM-10/PM emissions ratios but to decrease the total amount ofPM-10 emittedby a particular source.

The comments concerning the alleged conservative nature ofmodels used "during the early stages ofmodel development" fail to support the commenters' conclusion that the PM-in increments are overly stringent. As described earlier, the equivalent PM-iO increments developed by EPA are linked directly to the PM-10/PM emissions ratios for the sources ofPM in the NSR database-not to the modeled ambient TSP concentrations. The EPA utilized modeling results (i.e., predicted TSP ambient impacts), along with the calculated PM-10 impacts, to plot cumulatively the amount ofTSP and PM-10 increment (based on several trial increment levels) consumption occurring for eachPM source in the data base. Each of the resulting PM-la increment consumption curves was compared to theTSP increments consumption curve to determine which

one best approximated the same amount of overall PM-10 increment consumption. In theevent that the particular model used by a PSD applicant overestimated the source's TSP impact, then (1)the amount ofTSP increment consumed also would have been overestimated, and (2) the corresponding PM-10 impact and
amount ofPM-10 increment consumed would have been equally overestimated. Consequently, all ofthe plotted curves would reflect equal overestimations. Since all curves (TSP and PM-10) would have been affected similarly, identifying the equivalent curve should
notbe affected by any overestimations.

With respect to commenters' criticism of theuncertainties associated with the conversion ofPM emissions to PM-10 emissions, EPAbelieves that ittook a reasonable and technically sound approach. When source-specific particle size distributions were available, PM-la emissions estimates were made from them. When such Information was not available, PM-10 emissions estimates

were made based on particle size distributions for similar source or processes as found in the literature and using conservative engineering assumptions. Where appropriate, the resulting particle size distributions were checked forconsistency against the interim results of ongoing research within the Agency.

The EPA readily acknowledges the fact that the PM-10/PM emissions ratios
may vary considerably from one source category to another. As a result, a set of PM-10 increments which is equivalent in effect relative to each individual PSD

source is nottechnically possible. However, EPAbelieves that the Increment levels selected provide the best "fit" relative to the representative sample ofPSD sources included in the analysis.

As was reported in the preamble to the proposal, some sources consume
more ofthe available increments under the equivalent Class II PM-10 increments, and some consume less. There was essentially no difference in the percentage ofincrements consumed (i.e., less than 5percent difference) for about91 percent ofthe 249 NSR data base sources. Moreover, only four

sources were projected to violate the equivalent PM-10 increments levels

even though they demonstrated compliance with the TSP increments. In each case, control technology is available that could lower the emissions from new sources ofthese types such that those emissions would not cause violations ofthe new PM-10 increments.

In the case ofthe Class I increments, EPA found fora few sources that the selected PM-10 increments levels would result in agreater portion ofPM10 increments being consumed than of TSP increments. However, in nocase would a PM-10 increments violation be predicted.

The commenters who criticized EPA's

use ofPM emissions data (andmodeled ambient impacts) rather than ambient TSP data to develop equivalent PM-10 increments failed to understand how increments consumption is "measured" under the PSD program. Ambient data

are rarely, ifever, used to determine increments consumption. There are several reasons forthis fact. First, the predicted air quality impacts ofthe proposed new ormodified source must be based on modeling estimated potential emissions. Also, under certain circumstances, actual emissions changes that would be detected by ambient monitors are not considered to consume increments. States may also exempt certain temporary emissions activities from increments consumption. Finally, statutory provisions prohibit sources from receiving credit for dispersive effects ofstack heights which exceed good engineering practice. Accordingly, calculations ofincrements consumption have typically been accomplished by

### Federal Register / Vol. 58, No. 105 / Thursday, June 3, 1993 / Rules and Regulations

modelling source emissions without reliance on ambient air quality data.

In response to the comments calling for a two-tiered PM-10 increments system, EPA does not agree that particle distinction based on chemical composition should be considered in setting the levels ofthe PM-10 increments. This issue was raised previously when EPA proposed the PM10NAAQS. and EPA responded at that time that a size-specific, rather than a chemical-specific, indicator should be used in setting NAAQS forPM.1 7 The EPA continues to believe that particle size is ofprimary concern. Moreoveri a two-tiered system for measuring air quality deterioration would be inappropriate inlight ofthe fact that no such system exists for the NAAQS. It should benoted, however, that the PSD requirements do provide for the exclusion ofcertain emissions activities (i.e., temporary emissions) when a request is submitted by the Governor of

a State. The exclusion provision is discussed in more detail in Section II.D.6. (Exclusions from Increments Consumption).

Finally, concerning the form ofthe PM-10 increments, EPA finds no compelling reason within the commenter's argument to adjustthe proposed form. Interestingly, the commenter sought to establish consistency between the PM-10 increments and the PM-10 NAAQS recommending that the increments be expressed in a statistical form (as are the PM-10 NAAQS),.but saw no need to express the annual increments as arithmetic mean values even though the PM-la NAAQS areexpressed as such.

The commenter's concern that EPA's proposed deterministic form forthe PM-10 increments would require duplicative and redundant recordkeeping and compliance evaluations is unfounded because ofthe different data input typically required forthe increments andNAAQS analysis. That is, both the inventory ofsources and the source emissions input data tend to differ because ofthe differing nature ofthe two types ofanalyses. The emissions inventory neededto perform

an increments analysis includes only those sources whose emissions consume
a portion ofthe increments (asopposed to the baseline concentration) andthe emissions input data reflects the actual

'?In its original assessment ofthis Issue. EPA examined availablescientific information and concluded that the indicatorfor the primary standard should include thoseparticles small enough to penetrate to the thoracic region rather than include only certain chemical-epecific particles (52 FR 24634. July 1, 1987,pp. 24638-
24639.24717). emissions change since the baseline date. Thus, the fact that the compliance basis between the PM-la Increments and PM-10 NAAQS is different should provide no additional burden to the applicant or reviewing authority.

As explained in theproposal notice, the EPA's decision to convert the annual increments to arithmetic mean values

was based largely on practical considerations. The calculation ofan arithmetic mean value is a more straightforward method which is compatible withcurrent modeling computations. The commenter correctly pointed outthat the arithmetic mean value yields a higher value. However, in claiming that the proposed PM-10 increments were 12 percent more stringent than the statutory TSP increments, the commenter apparently overlooked the fact that EPA adjusted the initial PM-10 annual values by 12 percent to account forthe difference.

D.ImplementationIssues
1.Source Applicability

a. Background. The EPA did not propose any changes with respect to the criteria for determining whether a stationary source ofPM is subject to PSDreview. That is, In continuing the requirements ofthe existing PSD regulations, consideration will begiven
toboth "PM emissions" 18 and "PM-10 emissions" in determining PSD applicability. Under the existing regulations, a new stationary source is subject to PSD forPM ifithas the potential to emit any pollutant in major amounts and would emit either PM emissions orPM-10 emissions in 

### "significant" amounts [§ 52.21(i)(2)). An existing major stationary source is subject to PSD asa majormodification ofPM ifits proposed net emissions increase would result in significant amounts ofeither PM emissions orPM10 emissions.

Significant emissions ofPM would continue to be defined as either 25tons peryear (tpy)or more ofPM emissions,

or 15 tpyor more ofPM-10 emissions. However, a PSD applicant will only be required to perform an ambient impact analysis for PM-10 (NAAQS and increments) when the source has the potential to emit significant amounts of PM-10 emissions. The PSD requirement fora source to install BACT applies independently to either form ofPM

latheterm "particulate matter emissions" is defined asall finely divided solidorliquid material, other than uncombined water. emittedto theambient air as measured by applicable reference methods, oran equivalent oralternative method. specified by EPA orby atest methodin an approved SIP 140 CFR 51.1001. when it will be emitted in significant
amounts.

b.PublicComments. Seven
commenters opposed EPA's retention of

a dual applicability test for PM. These commenters argued that elimination of the TSP increments (in addition to EPA'sprior elimination ofthe TSP NAAQS) warranted a source applicability test based only on PM-10 emissions. The general response ofthese commenters was that "TSP" should be totally eliminated as aparameter of

concern in all portions ofthe PSD rules.

c. DecisionandResponseto Comments.After careful review ofthe original proposal and the EPA's rationale for a dual applicability test for PM, EPA has determined that itis necessary to retain the requirements, as proposed, at thistime. As indicated in the proposal, PM emissions continue to be regulated under avariety ofsection Ill new source performance standards (NSPS) (40CFR part 60). Even though EPA has now eliminated TSP as the ambient indicator for measuring compliance with both the PM NAAQS and thePM increments, in-stack measurements oftotal particulate emissions continue to serve as the specific basis for evaluating compliance under the NSPS. Thus, PM emissions mustbe regarded asa pollutant "subject to regulation under the Act" and, therefore, subject to PSDreview 

### [§ 52.21(b)(23)(i)].

2. Geographic Applicability

a. Background.Inthe October 5, 1989 Federal Registerproposal notice, EPA announced that the new increments generally would apply everywhere under a special system ofPSD area designations for PM-10 (54 FR 41225- 41226). This approach to applying the PM-10increments differed from the existing geographic applicability

roVisions forthe TSP increments which apply in areas designated as attainment orunclassified forTSP pursuant to section 107(d) ofthe Act] because EPA had determined that the section 107(d) area designation procedures did not then apply to PM10. The PSD increments for a pollutant do not apply when an area is designated nonattainment forthat pollutant.

In accordance with the proposed geographic applicability format forPM10, EPA proposed two specific actions. The first was to identify the surrogate

area designations forPM-10 in the State-by-State listings in subchapter C of 40 CFR part 81, where the area designations pursuant to section 107 of the Act are currently contained foreach criteria pollutant. The second action involved revising the definitions of 3162931630 Federal Register / Vol. 58, No. 105 / Thursday, June 3, 1993 / Rules and Regulations

"baseline area" and "baseline date" in the PSD regulations in parts 51 and 52
to incorporate references to the special PSD area designations for PM-10. The
current definitions of"baseline area" and "baseline date" make reference only
to "attainment" or "unclassifiable"

areas designated pursuant to section 107(d) ofthe Act and, thus, would not have provided a means for identifying baseline areas and baseline dates for PM-10.

b. PublicComments.Only one commenter expressed any objection to EPA's proposed geographic applicability concept. That commenter questioned EPA's plan to require the implementation ofthe new PM-10 increments in areas designated nonattainment for PM-10 NAAQS.

c.DecisionandResponse to Comments.The commenter apparently overlooked the fact that no "nonattainment" designations were to be made for PM-10 under the thenexisting area designation authority contained in section 107 ofthe Act. In any event, the commenter's concern that EPA would require consideration of PM-10 increments in areas that are not meeting the PM-10 NAAQS basically has been eliminated by new statutory requirements. As a result ofthe 1990 Amendments, it is no longernecessary for EPA to consider special geographic applicability provisions for the PM-10 increments.

By operation oflaw upon enactment ofthe 1990 Amendments certain areas

were designated nonattainment for PM10 [section 107(d)(4)(8) ofthe amended Act; also 56FR 56694, Nov. 6, 1991; 57 FR 56762, Nov. 30, 1992]. Specific part 'D (nonattainment) requirements apply
to the areas so designated (e.g., 57 FR 13498, April 16, 1992). All remaining

areas were initially designated unclassifiable for PM-10 by operation of law upon enactment ofthe 1990 Amendments [section 107 (d)(4)(B)(ii)J. Any area may subsequently be redesignated to a more appropriate attainment designation in accordance with procedures under section 107(d)(3) ofthe amended Act (e.g., 57 FR 43846, Sept. 22, 1992). Consequently, when the

new PM-10 increments take effect in each State, they will apply in all areas ofthe State designated as attainment or unclassifiable forPM-10 (section 161). Accordingly, the PM-10 Increments will
not apply in areas designated nonattainment for PM-10,

As aresult ofthe new area designation requirements forPM-10 under revised section 107 ofthe Act, EPA is not adopting in final form certain proposed changes that would have added language to the definitions of "minor source baseline date" and "baseline area" to refer specifically to the PSD areas for PM-10as they would have been listed in subchapter Cof40 CFR part 81. These changes are no longer necessary because attainment
status designations pursuant to section 107(d) ofthe Act are now required for PM-10. It shouldbe noted, however, that EPA proposed other changes to the definitions of "minor source baseline date" and "baseline area" that remain unaffected by today's action. These changes are discussed in the following section.

3. Retention ofTSP Baseline Dates and Baseline Areas

a. Background.The equivalent increments approach proposed by EPA included the retention ofthe baseline

areas and baseline dates established under the original TSP increments system. Under that system, the specific baseline area in which TSP increments consumption calculations were originally being made would carry over to the PM-10 increments system. Also, the major source baseline date for TSP (January 6, 1975), as well as any minor

source baseline date already established forTSP, would be considered the baseline date for PM-10, even ifthe PSD

source would not have triggered such date based on Its potential PM-10 emissions. In any attainment or unclassified areas where the minor

source baseline date (and therefore the baseline area)had not yet been set as of the implementation date ofthe PM-10 increments, the date would be set in the future by the first PSD application for a major new or modified stationary source havingthe potential to emit significant
amounts (15 tpy) ofPM-10.

b. PublicComments.Six commenters specifically objected to EPA's proposed retention ofthe original TSP baseline dates and baseline areas. These
commenters cited legal, technical and procedural problems associated with a provision which they perceived to require the retroactive calculation of
PM-10increments using irrelevant TSP baseline dates and areas.

Many ofthese commenters argued that section 166 ofthe Act applies only
to pollutants for which EPAestablishes

new NAAQS. Thus, ifPM-10 is a new pollutant forincrement-setting purposes under section 166 ofthe Act, prior consumption ofthe TSP-based increments is irrelevant and illegal. Several commenters alluded to EPA's promulgation ofNO2Increments, and the fact that EPA did not require retroactive increments consumption back to the original statutory baseline dates, to support their claim that EPA erred in proposing to utilize old TSP baseline dates and areas for PM-10 increments purposes.

Some ofthe commenters indicated that any requirement to calculate PM-10 increments based on previous TSP increments consumptions is illogical and unworkable. One commenter cited EPA's failure to provide a methodology for calculating prior PM-10 increments consumption. Another commenter stated that "[tlechniques are not currently available and probably never will be for accurately and consistently translating TSP increments consumption into PM-10 increments consumption." This commenter included as technical obstacles the %number and diversity ofindustrial

sources, varying PM-10/TSP ratios, and problems tracking major modifications and minor source contributions ofPM10 over the last 15 years.

Two commenters introduced implementation issues which they

.considered to bejustification for starting

over with new PM-10 baseline dates. One ofthese commenters stated that retention ofthe TSP baselines would penalize those areas which came into compliance with the TSP NAAQS, since those areas likely have already consumed a portion ofthe available increments and "would notreceive full PM-10 increments." Meanwhile, areas which failed to attain the TSP NAAQS would now be "awarded full PM-10 increments." The other commenter opposed EPA's position calling for the retention ofthe existing TSP minor

source baseline dates even where it could be shown that the source triggering thebaseline date would not have done so based on potential PM-10 emissions.

c.DecisionandResponseto Comments.The EPA continues to believe that it is appropriate to retain the original TSP baseline dates and baseline areas as part ofthe program for implementing the PM-10 increments. The PSD program established by Congress under the 1977 Act was designed to prevent significant deterioration ofair quality for the. pollutant PM-Congress did not designate what indicator was to be used. The establishment ofa new indicator for PM (both for theNAAQS and increments) does notmean thatEPA
must ignore all increments consumption ofPM which has occurred to date. Moreover, this would ignore Congress' underlying intent to prevent the deterioration oflocal air quality due to increased PM emissions. Ambient PM10, a component ofTSP, has always been counted toward measurements used to determine compliance with the

### Federal Register / Vol. 58, No. 105 / Thursday, June 3, 1993 / Rules and Regulations

TSP NAAQS. Itwouldbe difficult to
argue that amounts ofPM-10 emitted prior to the promulgation ofthe PM-10 NAAQS should not be counted for determining compliance with such standard simply because they were previously included as ameasure of TSP. "The EPA selected the PM-10
indicator for measuring increments consumption on the basis that it would
not be reasonable to continue to count larger particles in preventing significant deterioration when such particles were notpart ofthe measurement for determining compliance with the revised NAAQS forPM. The statutory framework certainly ties theNAAQS to the increments, andEPA felt compelled
to follow this approach. As mentioned earlier in this preamble. Congress did
not intend for EPA to redefine the statutory increments for PM simply by using a new indicator along with the

same numerical concentrations. Thus, EPA concluded that the promulgation of equivalent increments based on the new indicator, replacing the increments based on the old TSP indicator, represented the most reasonable alternative forpreserving the PSD system forPM established by Congress.

The addition ofnew section 166(0 under the 1990 Amendments supports EPA's final decision. Congress clearly intended to preserve the current PSD
process forPM when it provided for "[siuch substituted maximum allowable increases * * of equal stringency in effect as those specified in the provisions forwhich they are substituted." Moreover, Congress instructed EPA to retain theTSP increments until it promulgated the new PM-10 increments, thereby ensuring there would be no gap inthe protection ofair quality with respect to PM.

The EPA does notagree with those
commenters who suggest that it will be

more difficult for future PSD applicants
to calculate PM-10 increments consumption than TSP increments consumption. Each PSD Increments analysis is a case-by-case analysis involving the identification ofthe appropriate sources whose emissions

consume increments. It Is the responsibility of the applicant (under the direction ofthe permitting authority) to make such identification and to calculate the actual emissions for the affected pollutants accordingly. It

was never EPA's intention, as some
commenters have supposed, that a new applicant should utilize the results ofa previous TSP increments assessment and determine the amount ofPM-10 increments consumed based on the local ambient PM-1/TSP ratio. Increments consumption isbased exclusively on predictions from air quality dispersion models. The EPA recognized some time
ago that ambient monitoring data would be very difficult to use in the typical increments analysis (44FR 51924, 51944, September 5, 1979).

Concerning the commenter who felt that former TSP attainment areas would be penalized (in comparison with former TSP nonattainment areas) by EPA's decision to retain the original minor source baseline dates for TSP, EPA disagrees. It is true thatareas which werepreviously attainment for TSP likely will have already consumed

some portion ofthe available PM-10 increments. Generally, the fact thatthe
amount ofavailable increments has decreased is indicative ofthe economic growth whichhas occurred in the PSD

area.

In contrast, areas which were previously nonattainment forTSP did
not have the same growth opportunities because ofthe requirement to reduce emissions to the degree needed to attain the TSP NAAQS. In such areas new major source growth could not occur without the application ofvery stringent emissions controls and offsetting emissions reductions being obtained from existing sources in the same area. In some cases, TSP nonattainment areas

were under a federally-imposed construction ban which disallowed any major source growth forPM. Also,it should not be assumed that previous nonattainment areas for TSP, which are

now unclassifiable forPM-10, will always have the full amount ofPM-10 increments available. That is, inareas where the ambient concentrations in the

area are just below thePM-10 NAAQS level, the NAAQS-not the PM-10 increments-serve as the effective constraint on further PM-10 emissions growth. Thus, EPA believes that it is inappropriate to perceive the retention of the original TSP baseline dates as "penalizing" areas that were previously attainment for TSP.

In response to the commenter who opposed EPA's proposing to retain a TSP minor source baseline date that would not have been triggered on the basis ofpotential PM-10 emissions, EPA is today announcing a different policy from that originally proposed. The EPA has reexamined its original sition and now agrees that itwould inappropriate to retain aTSP minor

source baseline date when it can be shown that thePM-10 emissions from the source triggering the baseline date

were de minimis. In arriving atthis conclusion, EPA considered existing policy concerning the triggering ofthe minor source baseline date. That policy, in part, provides that a minor source baseline date will nolonger be considered set ifthe source which triggered the baseline date by submitting

a complete permit application no longer qualifies for that permit as a result of changes to the PSD requirements (so as to make such source eligible to have the permit rescinded).' 9

The EPA believes that the situation involving a source whose emissions would no longer beconsidered significant closely follows the circumstances under which apermit rescission would enable the minor

source baseline date to be changed. Section 169(4) ofthe Act establishes the submittal ofa complete application as the baseline triggering mechanism on a pollutant-specific basis. In recognition ofthe pollutant-specific nature ofthe minor source baseline date, thePSD regulations stipulate that the minor

source baseline date isestablished for a particular pollutant (1)on the date a complete application is received by the permitting authority, and (2)when the proposed source would have the potential to emit thatpollutant in a significant amount. The EPA has concluded that, in terms ofthe effect on the minorbaseline date, a source ofPM whose emissions are no longer considered significant because ofa regulatory change inthe applicable pollutant indicator should be treated the

same asa source that is no longer considered major.

In order to implement thisnew policy, EPA is modifying it's proposed revision ofthe definition of"minor

source baseline date" at §52.21(b)(14)(iv) to indicate that the Administrator will no longerconsider the minor sourcebaseline date to be triggered by a particular source when it

can be shown, to the satisfaction ofthe Administrator, that such source did not have the potential to emit significant
amounts ofPM-10. Any State having an EPA-approvd PSD program inits SIP may adopt a similar policyifit wishes
to do so [new §51.166(14)(iv)]. It should be noted, however, for purposes of determining the amount ofavailable PM-10 increments, the source which triggered the original minor source baseline date still consumes PM-10

1 91tis EPA'slongstanding policy to require generally thatonce a minorbaseline date is set by

aparticularsource via the submittal ofacomplete PSD permitapplication,such datewill remainin effect even when the applicationis voluntarily withdrawnor thepermit is denied. The policy as originallyannounced contained anexception, however, forany source originally defined as major underthe June1978 PSD regulations, butwhich

was no longerconsidered majorasaresult of regulatorychanges promulgatedon August 7,1980 (FR 52676,August 7,1980, p.52717). 3163131632 Federal Register / Vol. 58, No. 105 / Thursday, June 3, 1993 / Rules and Regulations

increments, since it is a major stationary

source whose PM-10 emissions have been increased after August 7, 1977 (the major source baseline date forPM) as a result ofthe construction or modification ofthe facility [§ 52.21(b)(13)(ii)(a)].

4. Implementation Date

a.Background.The EPA announced thatthe proposed PM-10 increments would be implemented under the State PSD programs as well as the Federal PSD program in accordance with the schedule set forth in section 166 ofthe Act. As discussed, section 166(b) specifically provides that new increments promulgated by EPA must be part ofan approved State PSD
program not later than 25 months from their date ofpromulgation. 2 0 In orderto apply the same implementation schedule to the new increments in both the State and Federal PSD programs, EPA proposed that the new increments wouldbecome effective 1year from their date ofpromulgation in § 51.166, and 25 months from theirdate of promulgation in § 52.21. Thus, States lacking an EPA-approved PSD program would have an opportunity to develop and submit to EPA an approvable program which includes the new PM-la increments; alternatively, implementation ofthe new increments under theFederal PSD program could have begun I year from the date of promulgation in §52.21.

b. PublicComments.Commenters basically expressed no opposition to the implementation schedule announced by EPA in the proposal notice. However,

one commenter, concerned about the need to address area source emissions in the PM-10 increments analysis, requested that "the effective date ofthe regulations should not precede the publication and distribution of guidelines * * * to determine the increase ordecrease ofarea source emissions from the baseline date."

c.DecisionandResponse to Comments.The EPA has given further consideration to the proposed implementation schedule and has concluded that implementation ofthe

new PM-10 increments under the Federal PSD program should not be delayed for 25 months as originally announced. The Act is clear in its requirements that (1)new increments

20naddition to the 1-year delay inthe effective date ofany new increments which EPA promulgates pursuanttosection 166 ofthe Act, section 166(b) provides each Statewith 9months to revise theircurrentPSD plan andtosubmit it to EPA forapproval. The EPAthen has 4months to review and issue adeterminationon the approval ofthe revised plan. become effective Iyear from the date of promulgation, and (2)State PSD
programs be allowed 25 months from the date ofpromulgation to implement
any new PSD increments. The EPA has determined that, inthe case ofthe PM10 increments, where the new increments would be substituted for existing increments to replace a pollutant indicator that is no longer used to measure NAAQS compliance, it is in thebest Interests ofthe PSD program to expedite the implementation date wherever possible.

The EPA's original concern for uniformity in the implementation date from one State to another is overshadowed by the benefits to both the PSD applicant and the reviewing authority derived by expeditiouslyeliminating the requirement for a TSP ambient impact review under the PSD
program. Moreover, sincethe implementation ofthe PM--10 increments involves the switching of indicators rather than the
commencement ofa completely new set ofincrements requirements (as was the

case with the new NO2increments), no apparent inequity results from the early implementation ofthe PM-10 increments in one State as compared to another State.

Consequently, EPA is today announcing that thePM-10 increments promulgated under the Federal PSD program in §52.21 will become effective 12 months fromtoday. The EPA or its delegated State program will begin implementation ofthe increments at that time. 21The PM-10 increments as promulgated today in § 51.166 will also become effective 12 months from today; however, the implementation date will be the date on which EPA approves each revised State PSD program containing the new PM-10 increments. States which fail to adopt the PM-10 increments within 9 months ofthe effective date could face sanctions and Federal implementation ofthat portion ofthe State's PSD permitting plan.
5. Grandfathering Provisions

a.Background.As part ofthe transition process for phasing inthe

new PM-la increments, the EPA proposed to exempt certain PSD applicants from the newrequirements for a PM-10 increments analysis. Specifically, EPA proposed to add grandfathering provisions to the PSD

21Statesimplementing anNSR programthrough

a delegation of §52.21 from EPA should, when
necessary, modify thatdelegation agreement over thenext 12 months toreflect the changes tothat regulation promulgated today. If States fail to changethe delegation agreement, EPA will become thepermittingauthority. regulations underboth part 51 and part 52, which would exempt from thePM10 increments analysis any PSD application for which a final permit determination has notyet been made when (1)the application, including a TSP increments analysis, is submitted before the implementation date ofthe

new PM-10 increments, and (2) the application is considered complete based on the existingrequirements on the date ofsubmittal. Instead, the proposed PSD project would be reviewed only for its ability to demonstrate compliance with the then existing TSP increments. It was not EPA's intent that the proposed exemption apply to other PSD requirements for PM-10 already in effect (e.g., PM-1 NAAQS compliance and the collection ofambient PM-10 monitoring data).

b. PublicComments.Two commenters responded to EPA's proposed grandfathering provisions. While both
commenters supported the grandfathering concept, one requested that applicability ofthe proposed exemption bebroadened to include any PSD applicant for which a TSP increments analysis has been completed, even ifthe remainder ofthe application is not yet complete. This
commenter argued that it is often difficult to determine when an application is complete, and that an applicant might have to repeat the increments analysis for PM "simply because [the permitting agency] has a disagreement with the permit applicant

over any minor element ofthe application."

c. DecisionandResponse to Comments.As proposed, EPA is adding the grandfathering provision to the PSD regulations in part 51 and part 52. In establishing this new provision, the EPA has chosen to rely upon the date of submittal ofa complete PSD application, instead ofthe date ofa complete increments analysis, for several reasons. First, EPA does not want to encourage applicants to submit applications containing a complete TSP increments analysis, while knowing that other portions ofthe application may be incomplete, simply to "lock in" the original increments analysis prior to the pointwhere the entire proposed PSD project is ready to be processed and reviewed. Moreover, the increments analysis does not stand alone relative to other information contained inthe permit application. Infact, the increments analysis is dependent upon the emissions and other source information contained elsewhere in the application.. Federal Register / Vol. 58, No. 105 / Thursday, June 3, 1993 / Rules and Regulations

Also, EPA does notintend to disallow the grandfathering ofa proposed project from the new PM-10 increments requirements merely because an unrelated orminor element ofthe overall application may be "incomplete." Nor does EPA believe that States would do so. A completeness determination generally acknowledges the receipt ofan application containing sufficient information to enablethe reviewing agency to begin the process of reviewing the contents ofthe application, but does not preclude the
agency from requesting additional information which maybe necessary as the review progresses. Finally, the new increments willnot become effective for I year after theirpromulgation inthe

case ofthe part 52 PSD regulations (generally longer for SIP-approved PSD programs). Applicants for PSDpermits will have ample time to plan the submittal oftheir applications, knowing when the effective date will occur. 6. Exclusions From Increments Consumption

a. Background.Section 163(c)(1)(C) of the Actprovides that any ;tate with an EPA-approved PSD plan may "issue orders orpromulgate rules" to exclude concentrations ofPM caused by "construction or othertemporary emissions-related activities" from increments consumption. The owner must submit an order ofruleto the Administrator, and the Administrator
must determine that the order ofrule is in compliance with the subsection. In its PM-10 increments proposal, EPA indicated it would consider any specific exclusion forPM-10 that a State may wish to add when itrevises its SIP to adopt PM-10 increments, provided such exclusion would notresult in permanent or long-term deterioration of air quality. "Prescribed burning" was given asan example of an activity which may oftentimesbe regarded as' temporary, but could alsobe considered
to have longer lasting (intermittent) effects under certain circumstances (54 FR 41228).

In orderto help make the appropriate determinations concerning activities whose temporary nature Is an issue, EPA sought comments on (1)whether exclusions should be contingent upon the use ofspecific mitigation measures; (2) what, ifany, accountability measures should berequired regarding the temporary nature ofair quality deterioration resulting from excluded activities; and (3) whether excluded activities should be "coordinated" or "scheduled" when occurring in a

common air shed tominimize the ambient impact from all excluded activities on a given day.

Finally, EPA pointed outthat, while certain exclusions from increments consixmption are available to any State withan approved SIP, such exclusions should notbe legally available under EPA's part 52 PSD regulations, even though a provision allowing such exclusion has been inadvertently retained in the Federal PSD program at §52.21. The Act, at section 163(c)(1), provides that only in States with implementation plans approved byEPA
may the Governor issue orders or promulgate rules providing for the applicable exclusions from increments consumption. The EPA originally allowed States to request the implementation ofthe exclusion provisions under the Federal PSD
program while Stateswere developing theirown initial PSD program (45 FR 52676, August 7,1980; p. 52677).

After May 7, 1981, exclusions were to be nolonger applicable underthe Federal PSD program; therefore, the

Srovision under § 52.21(f) should have

een rescinded at that time. Consequently, EPA proposed to delete the obsolete provision at 

### §52.21(f)to avoid any confusion as to its potential future use by States without approved PSD plans. In a related action, EPA also proposed to delete an erroneous provision from paragraph (f)(3) in § 51.166, which would have limited a State's use ofthe exclusion provision under §51.166 beyond May 7, 1981- the date after which a State lacking an approved PSD plan could not implement the exclusions from increments consumption.

b.PublicComments.The respondents to this issue focused their comments on prescribed burning activities rather than temporary activities in general. In all, six commenters expressed support for the exclusion ofPM-10 emissions causedby prescribed burning. The commenters' support was based on several factors including: Prescribed burning is a temporary activity, it typicallyreduces the overall amount of PM that might otherwise occur from wildfires, and it serves an essential ecological function. Two ofthe
commenters recommended that the exclusion ofprescribed burning activities shouldbe contingent upon such fires being conducted in accordance witha prescribed fire plan andbest management practices. Another
commenter expressed concern that the proposed ruleleaves to the States' discretion whether or not emissions from prescribed firewill consume increments. One commenter cautioned thatEPA lacked the authority to impose conditions on the required approval of exclusions from increments consumption adopted by the States. This commenter noted that theAct directs the Administrator only to determine whether a State's exclusion is in compliance with the provisions of 

### § 163 ofthe Act.

c.DecisionandResponse to Comments. The EPA supports the concept ofallowing States to exclude emissions causedby temporary prescribed burning activities from the PM-10 increments. It also agrees that there are important considerations tobe made asto howand when prescribed burning activities are carried out. However, EPA does not intend to impose specific conditions as to the type and nature of the prescribed burning or other pollutant-emitting activities as long as the activity itselfis ofa temporary nature. Consequently, EPA expects States to consider the
extent to which a particular type of prescribed burning activity is truly temporary, as opposed to those activities which can be expected to

occur in a particular area with some regularity over a period oftime.The Act provides that "construction and other temporary emissions-related activities" shallbe excluded from increments consumption pursuant to a State rule or orderupon which the public has been afforded an oportunityto comment.

As proposed, EPA is deleting the superfluous provision contained in §52.21(f) concerning the opportunity for States to exclude temporary emissions from increments consumption under the Federal PSD program. The States' eligibility forthis exclusion under the Federal PSD program ended on May 7, 1981. The EPA is also deleting paragraph (f)(3) of§ 51.166 which states that no exclusion under paragraph (f)of this section shall occur later than 9 months afterAugust 7, 1980, unless a SIP revision meeting the requirements of40 CFR 51.166 has been submitted to the Administrator.

The original purpose ofthis provision

was to restrict the implementation ofthe exclusion provisions underEPA's part 52 PSD regulations beyond May 7, 1981. Therefore, in order to avoid any confusion concerning the States' continuing authority to adopt new exclusion provisions pursuant to § 51.166, EPA is today deleting paragraph (f)(3) of §51.166.

7. Prevention ofSignificant Deterioration Monitoring

a.Background.The PSD regulations require that any application for apermit 31633

### 31634 Federal Register / Vol. 58, No. 105 / Thursday, June 3, 1993 / Rules and Regulations

must contain an analysis of ambient air quality, including air quality monitoring data as appropriate, in the area surrounding the proposed project. As a guide for determining whether it is necessary to include monitoring data for

a particular pollutant,EPA has defined specific ambient concentration thresholds [§52.21(i)(8)(ffl. When EPA amended the PSD regulations to account for the revised PM-10 NAAQS in 1987, it added a significant ambient concentration forPM-10 (10 gg/m 3

,24- hour average) to the list of significance levels, which already included a significant ambient concentration for TSP.In the October 5,1989 proposal for PM-10 increments, EPA proposed to eliminate the requirements for ambient TSP monitoring data in conjunction with the replacement ofthe TSP increments. Accordingly, the significant ambient concentration forTSP was proposed to be deleted from the PSD regulations. Thus, with respect to PM, only PM-10 would be subject to the requirement for ambient monitoring data.

b. PublicComments. Only a few
comments were received concerning this issue. Those who responded agreed that the ambient data requirements for TSPshould be eliminated once EPA promulgates new PM-10 increments replacing the existing TSP increments. Onecommenter went a step further stating thatEPA had overstepped the applicable regulations by continuing to require TSP monitoring data beyond the time when the PM-l0 NAAQS were adopted. This commenter stated that "[mlonitoring is required only for pollutants forwhich there are NAAQS."

One commenter representing the mining industry claimed that "models and emission factors are not accurate enough to permit surface coal mines to demonstrate that short-term 24-hour increments will notbe exceeded." This commenter thus recommended that, pending refinement ofexisting air quality dispersion models, the PSD regulations should allow surface coal mines to demonstrate compliance with short-term PM-10 increments via ambient monitoring data.

c.DecisionandResponse to Comments.Consistent with its proposed action, EPA is today deleting the significant ambient concentration for TSP from paragraph (i)(8)(i) inboth the part 52 PSD regulations and the part 51 SIP requirements forPSD. The EPA will

no longer require PSD applicants filing for aFederal PSD permit to submit preapplication monitoring data forTSP,

nor will EPA require postconstruction TSP data. With the replacement ofthe TSP increments, EPAconsiders only PM-1 to be regulated with respect to ambient indicators forPM. Thus, only ambient PM-10 data will be required where applicable.

States will notbe required to request ambient TSP data either. However, ifa State wishes to continue requiring the submittal ofsuch data, it has the authority to do so. Some States continue
to define ambient air quality standards in terms ofTSP (in addition to the national standards based on PM-10), and may elect to continue requiring the submittal and evaluation ofambient TSP data to determine compliance with such standards.

Concerning the comment thatEPA incorrectly required the submittal of ambient TSP data after the date when the PM-10 NAAQS were promulgated, EPA wishes to point out thatits policy has been to regard TSP as a noncriteria pollutant (withPM-10 being the criteria pollutant) withrespect to PM for any

area where the PM-10 NAAQS have been ineffect. Underthe PSD requirements, the submittal ofambient data for a noncriteria pollutant is discretionary on the part of-the permit reviewing authority [§ 52.21(m)(1)(b)(ii)]. Only in cases where the State PSD program continued to implement the TSP NAAQS (pending adoption ofthePM-10 NAAQS) was TSP regarded as the criteria pollutant and still subject to the PSD monitoring data requirements.

The commenter who alleged inaccuracies with a specific EPA model and PM emissions factors for determining surface coal mine compliance with the 24-hour increments focused on the use ofthe dispersion model,known asthe Industrial Source Complex Model (ISC), with AP-42 emissions factors. Section 234 ofthe 1990 Amendments (104 Stat. 2399, 2530) provides that prior to use of the ISC model using AP-42 emissions factors to determine the effect on air quality offugitive particulate emissions

om surface coal mines, for purposesof

new source review or for purposes of demonstrating compliance with the NAAQS applicable to periods of24 hours or less,EPA is to assessthe accuracy ofsuch model and emissions factors. Section 234 further provides that,in the meantime, Statesmay use alternative empirical based modeling approaches, based on guidance provided by EPA, to determine the effects on air quality offugitive particulate emissions from surface coal mines.

The EPA is undertaking ajoint study with the mining industry to determine the ability ofEPA'sISC model using AP-42 emissions factors to accurately predict short term ambient concentrations ofPM-10 from surface coal mining activities. Until EPA completes the study as called forunder section 234, EPA intends to allow estimates of24-hour increment impacts caused by fugitive emissions from surface coal mines to be made on a caseby-case basiswith current EPA models.22Ifsuch estimates predict ambient violations ofthe 24-hour PM10 increments, alternative methods, including empirical based modeling,
may be applied on a case-by-case basis. Section 3.2 ofEPA's Guideline on Air Quality Models (Revised), (EPA 450/2- 78-027R. July 1986), sets out the procedures for case-by-case approval of non-guideline EPA models.These procedures should be observed in using any non-guideline model, including empirical based techniques, to determine the prospective impact on the 24-hour increments offugitive particulate emissions from those new or modified surface coal mines subject to PSD. 2 3 Anymonitoring data which are used for purposes ofdemonstrating the ambient impacts ofsurface coal mining activities should be based on monitors which are operated in accordance with EPA regulations and guidelines, including requirements forquality

assurance for air quality data as contained inAppendix B of40 CFRpart 58.

8. Area Source Impacts

a.Background.After the minor source baseline date has been established for a particular area, emissions changes occurring at area sources, including mobile sources, will affect the amount ofavailable increments within that baseline area. Consequently, PSD applicants will be required to determine the extent towhich PM-10 emissions increases ordecreases from area sources have occurred in the area ofthe proposed new source or modification. In the proposal notice, EPA indicated that emissions from motor vehicles and residential wood combustion will have

agreater impact on the PM-la increments than such emissions had on the original TSP increments.

22 Section 234 references the use of the ISCmodel with AP-42 emissions factors to "determine" the effect onair quality.This provision does not prohibitles thanfinally determinative uses.

23During thisInterim period States are not required to. but "may" use, alternative empirlcal based modeling approaches consistent with the guidance described above. States retain discretion

to use orrequire reasonable assessment tools, so Ionsas themialmum Federal reqitrementsae satisfied I Wiscondn Publ Intervenor v. Mortler. liI S.CL. 2470 (1991)).Federal Register / Vol. 58, No. 105 / Thursday, June 3, 1993 / Rules and Regulations

b. PublicComments.One commenter expressed concern about the lack ofEPA guidance related to the determination of

area source impacts on the PM-10 increments. The commenter recommended that EPA issue such guidance prior to the effective date of the PM-10 increments.

c.DecisionandResponse to Comments.The kinds ofarea sources that will consume PM-lu increments

are essentially the same sources that have been affecting the TSP increments. Since EPA's promulgation ofPM-10 NAAQS in 1987, EPA has been reviewing the available PM emissions factors, including those for certain types ofopen area dust sources, and developing PM-10 emissions factors to enable States to review their PM emissions inventories and SIP's. Applicable guidance is contained in an EPA document entitled "Gap Filling PM-10 Emissions Factors for Selected Open Area Dust Sources" (February 1988, EPA-450/4-88-03). In addition, other PM-10 emissions factors for area

sources can be found in EPA's "Compilation ofAir Pollutant Emissions Factors, AP-42," (Supplement D, September 1991). Interested persons should contact EPA to determine whether other PM-10 emissions factors
may be available for specific types of activities.

In addition to the development of specific PM-10 emissions factors, EPA ispresently developing special guidance
to assist in the calculation ofincrements consumption resulting from mobile

source emissions. This guidance began with a focus on the impacts on the NO2 increments, however, EPA intends to expand thiseffort to address the PM-10 increments as well. This and other forms ofPSD increments guidance will continue tobe prepared as needed.

E. Other Issues

1. TSPArea Designations

The replacement ofthe TSP increments with PM-10 increments which operate independently from the section 107 area designations forTSP will negate the need forthe TSP designations to be retained any longer. In the proposal, EPA stated that it would automatically delete the TSP area designations from the listings under subpart Cof40 CFR part 81 as each State replaced the TSP increments with the new PM-10 increments. Specifically, EPA stated that the actual deletion ofthe TSP designations for each State would occur at the same time that EPA either (1)approves a State's revised PSD program containing the PM-10 increments, (2) promulgates the PM-10 increments Into a State's SIP where the State chooses notto adopt the increments on their own, or (3)
approves a State's request fordelegation ofPSD responsibility under § 52.21(u).

The EPA received no comments concerning this particular action. Atthe appropriate time, EPA intends to proceed with the elimination ofthe TSP

area designations. Generally, the first TSP area designations to be deleted will be those in'States where EPA has the legal responsibility forimplementing the PSD program pursuant to § 52.21. In those cases, EPA will eliminate the TSP designations when the PM-10 increments become effective under §52.21 on June 3, 1994. For those States with approved PSD programs, EPA will eliminate theTSP designations fora particular State at the same time that EPA approves the revision to that State's PSD rule, which should occur no later than July 3, 1995. Ifa Statewith an approved PSD program wishes to receive delegated authority as an interim measure to implement the PM10 increments prior to the date when its

own PSD rules arerevised, EPA will delete the TSP areas forthat State at the

same time that it approves such delegation ofauthority. However, the date on which these events may occur cannot precede the effective date ofthe PM-10 increments in thePSD regulations under §52.21.

2. Regulatory Impact Analysis (RIA)

The E.O. 12291 requires EPA tojudge whether a proposed regulation is "major" and therefore subject to the requirement fora RIA. A regulation is defined as major ifeither (1)the net annualized cost ofcontrol (including capital charges) exceeds $100 million
peryear, or (2) firms affected by the regulation incur a significant (greater than 5percent) increase In the price of goods. Using worst-case assumptions and conservative costing methods, EPA analyzed the effects ofthe proposed PM-10 increments and found that the total annualized fifth-year costs will-be well under $100 million, and product price increases will be insignificant for any affected firm. Based on these findings, EPA concluded that the proposed regulations would notbe considered major.

One commenter took issue with EPA's conclusion that the proposed increments do not constitute a major regulation. The commenter called EPA's determination "fundamentally flawed," claiming that it was based only on a "cursory analysis of 12 individual plants, and failed to extrapolate these results to industry asa whole." The EPA disagrees with the commenter's claim that the analysis was flawed because it failed to consider "industry as awhole." The analysis performed by EPA considered only that portion ofindustry which was projected
to beadversely affected by the proposed rule. The EPA is not obligated to consider control costs that would be required independently from the proposed regulatory requirements. Underthe existing PSD regulations, eachnew or modified major stationary

source is already required to apply the BACT forPM-10 emissions when they would be emitted in significant
amounts. This regulation will generate costs only when the proposed new PM10 emissions from a particular stationary source (after application of BACT)are predicted to cause a violation ofthe PM-10 increments, and the PM emissions increase did not cause a violation ofthe TSP increments. Therefore, inthe analysis performed by EPA, it was only necessary to consider the additional control costs which could be Incurred directly as a result ofthe

new requirements.

As part ofits cost analysis, EPA initially identified those sources in the NSR data base that demonstrated compliance with theTSP increments, but were estimated to have PM-10 air quality impacts exceeding the levels of

e PM-10 increments. Next, based on the number ofaffected sources in each

source category, EPA projected the number ofnew facilities within that

source category that would potentially exceed the PM-lu Increments in the fifth year (EPAtypically uses a 5-year timeframe forcost estimates associated with the RIA). The estimated cost associated with applying the additional level ofcontrol to each such source was determined to arrive at the total costs attributable to the proposed PM-10 increments.

The predicted equipment costs and price increases resulting from the 1988 economic impact analysis fell considerably short ofthe critical values used to determine whether the rulemaking constitutes a major action. Nevertheless, because ofthe amount of time thathas elapsed since the analysis

was completed, EPAreexamined the original analysis to determine whether the assumptions made therein and the associated dollar values changed substantially over the period oftime since the analysis was performed. Based

on that reexamination, EPA estimates that the equipment costs inthe report would increase byroughly 15-20 percent ifthey were updated to current dollars. Similarly, annual operating
costs stated inthe report could increase 31635

### 31636 Federal Register / Vol. 58, No. 105 / Thursday, June 3, 1993 / Rules and Regulations

by a similar amount. However, this level ofincrease would notalter the status of the rulemaking.

IV. Administrative Requirements

A. ReferenceDocuments
1.Radian Corporation. Technical Report-Equivalency ofAlternative PM-10 Increments. Prepared for U.S. EPA. Office ofAir Quality Planning and Standards. Research Triangle Park, North Carolina. March 1988.

2. Radian Corporation. Cost and Economic Impact Assessment forPM10 Increment Options. Prepared for U.S. EPA. Office ofAir Quality Planning and Standards. Research Triangle Park, North Carolina. April 1988.

3. Shumaker, 

### J.L., Radian Corporation (1988). Evaluation ofSource Impacts Associated With PM-10 Increment Options.Memorandum to Daniel J. deRoeck. February 15, 1988.

4. Pandullo, R. F., Radian Corporation (1988). Protection Against Adverse Class ITSP Impacts Afforded by PM-10 Increments. Memorandum to Daniel 

### J. deRoeck. September 28, 1988.

5. Frank, Neil H., U.S. EPA, Monitoring and Reports Branch. Difference Between Arithmetic Mean and Geometric Mean TSP. Memorandum to John Bachman and Henry Thomas. June 2,1980.

6.Frank, Neil H., U.S. EPA, Data Analysis Section (1984). Update on the Difference Between Arithmetic and Geometric Means forTSP. Memorandum to John Bachman. September 1, 1983.

7.Tikvart, Joseph A., U.S. EPA, Source Receptor Analysis Branch (1989). Comparison ofModel Estimates forDeterministic vs. Statistical Standards. Memorandum toEdward J. Lillis. April 4, 1989.

8. Radian Corporation. PM-10 Area Sources Paper. Prepared for U.S. EPA. Office ofAir Quality Planning and Standards. Research Triangle Park, North Carolina. February 1988.

9. Vatavuk, William, U.S. EPA, Cost and Economic Impact Section (1983). Review ofCost and Economic Impact Assessment forPM-10 Increment Options. Memorandum to DanielJ. deRoeck. March 11, 1993.

10. Vatavuk, William, U.S. EPA. Follow-up to March 11, 1993 Memorandum to Daniel J.deRoeck. March 16, 1993.

B.(Executive Order12291)

UnderE.O. 12291, EPA must judge whether a regulation is a "major rule" and therefore subject to the requirement for preparation ofa RIA. This ruling is
not a major rulebecause it would result in none ofthe adverse economic effects
set forth in section 1ofE.O. 12291 as grounds for finding a regulation to be major.

Thisregulation was submitted to the Office ofManagement and Budget (OMB) for review. Written comments from OMB to EPA and any EPA
response are included in Docket A-88- 19.

C. Paperwork ReductionAct

Under the Paperwork Reduction Act (44 U.S.C. 35.01) Federal agencies must obtain OMB clearance forcollection of information from ten or morenonFederal respondents. Thisrule does not contain any information collection requirements, and so does notrequire OMB clearance.

D. EconomicImpact Assessment

Section 317 ofthe Act requires the Administrator to prepare an economic Impact assessment for any regulations tunder part C oftitle I (relating toPSD ofair quality). An economic impact
assessment was prepared for the proposed PM-10 increments levels and also for other alternative levels.The requirements ofthis section were considered inthe formulation ofthe proposed increments to ensure that they would represent the best system for preventing air quality deterioration, considering costa. The economic impact
assessment is included in the docket.

E.RegulatoryFlexibility Act Certification

Pursuant to the provisions ofU.S.C. 605(b), Ihereby certify that this rule, if promulgated, will nothave a significant economic Impact on a substantial number ofsmall business entities (46 FR 8709). In accordance with the PSD requirements set forthunder part Cof the Act, the preconstruction review requirements ofthisrule apply only to major new and modified stationary

sources ofair pollution.

F.EffectiveDate

These rules are effective June 3, 1994.

List ofSubjects

40 CFRPart 51

Administrative practice and procedure, Airpollution control, Intergovernmental relations, particulate matter, Reporting and recordieeplng requirements.

40 CFRPart52

Air pollution control, Intergovernmental relations, Particulate matter, Reporting and recordkeeping requirements. Dated: May 14. 1993.
Carol M. Browner,
Administrator.

PART 51-REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITrAL OF IMPLEMENTATION PLANS

For the reasons set forth inthe preamble, part 51, chapter 1,title 40 of the Code ofFederal Regulations, is amended as follows:

1.The authority citation forpart 51 continues to read as follows:

Authority: 42 U.S.C. 7401-7671q.

2. In §51.166, paragraphs (b)(3)(iv) and (i)(8)(i)(c), the tables in paragraph (c) and paragraph (p)(4) are revised; paragraph (0(3) isremoved and reserved; and paragraphs (b)(14)(iv), (b)(15)(iii), and (i)(12) are added to read

as follows:

§51.166 Prevention ofsignificant deterioration of airquality.

* 0 * * *

(b)" ' (3) * * (iv) An increase or decrease in actual emissions ofsulfur dioxide, particulate matter, or nitrogen oxides, which occurs before the applicable minor source baseline date is creditable only if it is required to be considered in calculating the amount ofmaximum allowable increases remaining available. With respect to particulate matter, only PM10 emissions can be used to evaluate the
net emissions increase forPM-10.

* * * * *

(14) (iv) Any minor sourcebaseline date established originally for the TSP increments shall remain in effect and shall apply forpurposes ofdetermining the amount ofavailable PM-10 increments, except that the reviewing authority may rescind any such minor

source baseline date where it can be shown, to the satisfaction ofthe reviewing authority, that the emissions increase from the major stationary
source, or the net emissions increase from the major modification, responsible for triggering that date did
not result in a significant amount of PM-10 emissions.
(15) * * * (iii)Any baseline area established originally for the TSP increments shall remain in effect and shall apply for
purposes ofdetermining the amount of available PM-10 Increments, except that such baseline area shallnot remain in effect ifthe permit authority rescinds the corresponding minor sourceFederal Register / Vol. 58, No. 105 / Thursday, June 3, 1993 / Rules and Regulations

baseline date in accordance with paragraph (b)(14)(iv) ofthis section.

*

. * * *

(c)'

Maximum allowable InPcrease

per cubo Ctae r
a~mi

Particulate matter PM-10, annual azthmetlc

m ean 4 PM-la. 24-hrmaxamm 8 Sulfurdioxide: Annual athmetic mno .... 2 24-v maximum

................. 5 3-hrmaximum

........... 25 Nitrogen dioxide: Annual

metIc mean .......................... 2.5

Ca ii

Particulate matter: PM-I0, annual ariftmetc

mean

................. . 17 PM-0, 24-hr maximum. 30 Sulfur dioxde: Annual arithnetic mean
.... 20 24-hr maximum

................. 91 3-hrmaximum

.................. 512 Nitrogen dioxide: Annuar'adthmetlcmean

.... 25



### am III

Pariculate matter: PM-IO, annual adtmtlc

ma.........o 34 PM-O, 24-hrmaximum 60 Sulfur dioxide: Annual arithmetic mean
.... 40 24-hr maximum

................. 182 3-hr

. ................... 700 Nitrogen dioxide: Annual wdthmetI mean

.......................... 

### so
(f) * 0 (3) [Reserved)

O * * * 

### (i)* * * 

### (8)' *** 

### (I). * • (c)Particulate matter-10 Ig/m3 of PM-10, 24-hour average.

(12) The plan mayprovide that the permitting requirements equivalent to those contained in paragraph (k)(2) of this section shall not apply to a stationary source or modification with respect to any maximum allowable increase for PM-20 if(I)the owner or operator ofthe source or modification submitted an application for a permit under the applicable permit program approved under the Actbefore the provisions embodying the maximum allowable increases forPM-10 took effect aspart ofthe plan, and (ii)the permitting authority subsequently determined that the application as submitted before that date was complete. Instead, the applicable requirements equivalent to paragraph (k)(2) shall apply with respect to the maximum allowable increases forTSP

as in effect on the date the application

was submitted.

* * * * a

(p) *• (4)* * /

Maximum allowable InPollutant crease (micrograms

per cubic

meter)

Particulate matter: PM-10, annual arithmetic

mean.................... 17 PM-10, 24-hour maximum 30 Sulfur dioxide: Annual arithmetic mean
.... 20 24-hr maximum

................. 91 3-hrmaximum

................... 325 Nitrogen dioxide: Annual adthmetic mean . ..... 25

* * * * *

PART 52-APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

For the reasons set out in the preamble, part 52, chapter I, title 40 of the CodeofFederal Regulations, is amended as follows:
1.The authority citation forpart 52 continues to read as follows:

Authority. 42 U.S.C. 7401-7642 as amended by the Clean Air ActAmendments of 1990,Pub. L. No. 101-549, 104 Stat 2399 (Nov.15, 1990), unless otherwise noted.

2. In 52.21, paragraph (b)(3)(iv), the tables in paragraph (c) and paragraph (p)(5), and the third item in paragraph (i)(8)(i) are revised; paragraph (f)is removed and reserved; and paragraphs (b)(14)(iv). (b)(15)(iii), and (i)(13) are added to read as follows:

152.21 Preventlon of significant deterloraton of air quality.

*I * * * *



### (b)"

(3) * * * (iv)An increase ordecrease in actual emissions ofsulfur dioxide, particulate matter, or nitrogen oxide, which occurs before the applicable minor source baseline date is creditable only ifitis required to be considered in calculating the amount ofmaximum allowable increases remaining available. With respect toparticulate matter, only PM10 emissions can be used to evaluate the net emissions increase for PM-10.

a * * * $

(14) * * * (iv)Any minor sourcebaseline date established originally forthe TSP increments shall remain in effect and shall apply forpurposes of determining the amount ofavailable PM-10 increments, except that the Administrator shall rescind a minor

source baseline date where it can be shown, to the satisfaction ofthe Administrator, that theemissions increase from the major stationary
source, ornet emissions increase from the major modification, responsible for triggering that date did not result in a significant amount ofPM-10 emissions.

(15) * * * (iii) Any baseline areaestablished originally forthe TSP increments shall remain in effect and shall apply for purposes ofdetermining the amount of available PM-10 increments, except that such baseline area shall not remain in effect Ifthe Administrator rescinds the corresponding minor sourcebaseline date in accordance with paragraph (b)(14)(iv) ofthis section.

* * * * a

(c) *

Maximum allowable InPollutant crease (mkirorams

per cubic

meter)

classI

Particulate matter PM-1O, annual arithmetic

m oan................... 4 PM-10, 24-hrmaximum

.... 8 Sulfur dioxide: Annual adrthmetlc mean .... 2 24-hr maximum

................. 5 3-hrmaximum

................... 25 Nitrogen dioxide: Annual adthmetic mean

.... 2.5

Class 1I

Particulate matter PM-10, annual arithmetic

mean
........... 17 PM-10, 24-hr maximum 30 Sulfurdioxide: Annual aritmtic mean . 20 24-hr maximum

.... ........... 91 3-hr maximum

................... 512 Nitrogen dixid: Annual ardhmetic mean .... 25

Class III

Particulate matter PM-lO, annual arithmetic

me1an........................ 34 PM-,10 244 maximum... 60 Sulfur dioxide: Annual arithmetic mean. 40 31637316,38 Federal Register / Vol. 58, No. 105 / Thursday, June 3, 1993 / Rules and Regulations

Maximum allowable Increase Pollutant (micrograms per cubic meter)

24-hr maximum

................. 182 3-hr maximum

................... 700 Nitrogen dioxide: Annual arithmetic mean

.... 

### 50

* * * * *

(f)[Reserved] 

### (i)* * * 

### (8) * * * 

### (1) * * *

Particulate matter-10 g/ M3 ofPM10, 24-hour average;

* * * * *

(13) The requirements in paragraph (k)(2) ofthis section shall not apply to a stationary source or modification with respect to any maximum allowable increase for PM-10 if (i)the owner or operator ofthe source ormodification submitted an application for a permit under this section before the provisions embodying the maximum allowable Increases for PM-10 took effect in an implementation plan to which this section applies, and (i) the Administrator subsequently determined that the application as submitted before that date was otherwise complete. Instead, the requirements in paragraph (k)(2) shall apply withrespect to the maximum allowable increases forTSP

as ineffect on the date the application

was submitted.

* * * * *

(p) * * • (5* * * Maximum allowable increase Pollutant (micrograms per cubic

meter)

Particulate matter PM-10, annual arithmetic

mean

........................... . 17 PM-10, 24-hr maximum

.... 30 Sulfur dioxide: Annual arithmetic mean

.... 20 24-hr maximum

................. 91 3-hr maximum

................... 325 Nitrogen dioxide: Annual arithmetic mean

.... 25

* * * * * [FRDoc. 93-12372 Filed 6-2-93; 8:45 am]

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