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31622 Federal Register / Vol. 58, No. 105 / Thursday, June 3, 1993 / Rules and Kegulauons

ENVIRONMENTAL PROTECTION

AGENCY

40 CFR Parts 51 and 52

[AD-FRL--4658-4]

Prevention of Significant Deterioration

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

of significant 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 fulfills EPA'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 for judicial review must be

filed on or before July 6, 1993 in the

U.S. Court of Appeals for the DC Circuit.

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, at EPA'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 of Air Quality

Planning and Standards, U.S.

Environmental Protection Agency,

Research Triangle Park, North Carolina

27711, (919) 541-5593.

SUPPLEMENTARY INFORMATION: The

contents of today's preamble are in the

following format:

I. Introduction

II. Background

A. The PSD Program B. Proposal of PM10 Increments

C. The 1990 Amendments

Ill. Discussion of Final Rule and Comments

A. Legal Authority 1. Background 2. Public Comments

3. Decision and Response to Comments

B. Selection of the Equivalence Approach

1. Background

2. Public Comments

3. Decision and Response to Comments

C. Development of Equivalent Numerical

Levels

1. Background

2. Public Comments

3. Decision and Response to Comments

D. Implementation Issues

1. Source Applicability

2. Geographic Applicability

3. Retention of TSP Baseline Dates and

Baseline Areas

4. Implementation Date

5. Grandfathering Provisions

6. Exclusions From Increments

Consumption

7. Prevention of Significant 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 increments for PM. 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

of 1977 (1977 Amendments). The

original increments were specified in

terms of ambient concentrations of TSP,

which was the form of PM addressed in

the NAAQS at that time. The revised

increments for PM, measured as PM-10,

restrict increases in ambient

concentrations of PM-10 to the

following levels: 4 g/m 3 (annual

arithmetic mean) and 8 V/M3 (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/m3 (annual arithmetic mean)

and 60 g/m3 (24-hour maximum) for

Class ITT areas. The implementation of the new PM10 increments will utilize the existing

baseline dates and baseline areas for

PM. As such, PM increments, measured

as PM-10, already consumed since the

original baseline dates established for

TSP will continue to be accounted for,

but all future calculations of the amount

of increments consumed will be based

on PM-10 emissions beginning on the

implementation date of the new PM-10

increments. The implementation date

will vary depending on the State

implementation plan (SIP) approval

status of the applicable PSD program.

For the Federal PSD program, the

implementation date is 1 year from

today. For EPA-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 of the PSD program and the

relevant 1990 Amendments, and

includes a discussion of the significant

public comments EPA received on the

proposed rule, as well as EPA's

responses to these comments.

II. Background

A. The PSD Program

Although the Clean Air Act

Amendments of 1970 provided a

scheme to address emissions in areas of

the country where pollution levels

exceeded the NAAQS, the Act at that

point contained no explicit provision

addressing potential deterioration of

ambient air quality in those areas where

pollutant levels were below the

NAAQS. In 1972, the Sierra Club

brought suit alleging that the Act

required State plans to include

measures to prevent the "significant

deterioration" of the air in parts of the

country already in compliance with the

NAAQS. The court held that the Act, by

declaring the legislative "purpose of

protecting and enhancing" air quality

[section 101(b)(1)), mandated that EPA

require States to protect the air quality

of clean areas from significant

deterioration. I In 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 of title I of the 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 of new stationary sources and

modifications of existing stationary

sources to prevent significant

ISee Sierra Club v. Ruckelshous, 344 F.Supp.

253, 256 (D.D.C. 1972), affd per curium, 4 ERC

1815 (D.C.Cir. 1972)oaff d by an equally divided

court, sub. nom Fri v. Sierra Club, 412 U.S. 541

(1973).

2 All section references are to the Act unless

noted (sections 100-183,42 U.S.C. 7401-7671q).

Part C also includes a subpart which provides for

the protection of visibility in certain national parks,

wilderness areas and other so-called "mandatory

Class I Federal areas" (see section 169B).

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deterioration of existing air quality

levels. 3

The PSD program mandated by

Congress is required to balance three

primary goals, as specified by section

160 of the Act. The first of these goals

is to protect public health and welfare

from actual or potential endangerment.

This goal includes the protection of

existing air quality in all areas where

the ambient pollutant concentrations

required by the NAAQS are currently

being achieved. The second goal

emphasizes the protection of air quality

in national parks, wilderness areas, and

similar areas of special 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 of growth on air quality by

the State and local communities, and

only when such growth would be

consistent with the preservation of clean

air resources.

The PSD program in part C is

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 of air pollution use best

available control technology (BACT) in

order to minimize pollution from these

sources. The BACT mechanism is

intended to result in the 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 policy judgments by

Congress. First, minimizing pollution

from new and modified stationary

sources serves the statutory goals of

protection and enhancement of air

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 of the goals of

the PSD program. Third, the effective

reduction of pollution from any single

new or modified stationary source will

increase opportunities for additional

growth within the constraints of the air

quality protection requirements of the

PSD program.

3 The PSD requirements apply to areas classified

pursuant to section 107 of the Act as attainment or unclassifiable. For pollutants for which no NAAQS

have been promulgated, and for pollutants not

subject to the section 107 area designation process.

the PSD requirements apply everywhere as long as an area Is designated as attainment or unclassifiable

for at least one pollutant for which NAAQS do exist

(i.e.. for at least one criteria pollutant).

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. 4 In Section 163 of

the Act, Congress initially defined

statutory numerical increments for PM

and sulfur dioxide (SO 2) as the

maximum permissible increases, above

baseline levels, in the ambient

concentration of the pollutants in a PSD

area. Congress determined that the PM

increments levels it adopted provide for

both protection of air 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, as Class I areas.

Consequently, the most restrictive

increments apply in this class. Section

162(a) of the Act established "mandatory" Class I areas, which

include all international parks as well as

national parks, national wilderness

areas, and national memorial parks

exceeding certain sizes and existing on

the effective date of the 1977

Amendments.5 These Class I areas are

termed "mandatory" because Section

162(a) also prohibits the States (or in the

case of Indian lands, Indian tribes) or

EPA from redesignating these

mandatory Class I areas to any less

protective classification.

Less restrictive increments apply in

areas designated as Class H or Class III.

Initially, Congress classified as Class 11

areas all attainment and unclassifiable

areas that were not classified as Class I

areas. Section 164 of the Act allows that

Class II areas may be redesignated by

the States to Class I or Class III under

certain circumstances. The Class I area

designation allows States (or Indian

tribes) to permit more deterioration in

air quality in specific areas which States

may target for higher levels of industrial

development and consequent growth in

4The increments for PM enacted by Congress in

1977 and listed in 163 were based on the NAAQS

for PM. which, until July 1,1987, used TSP as the

unit of measurement (indicator) for ambient PM

concentrations.

3 Under the 1990 Amendments. Congress enacted new language which affects the boundaries of the

mandatory Class I areas Section 162(aX4) now stipulates that the boundaries of mandatory Class I areas must conform to any changes occurring since

the date of their original classification in 1977.

Previously, the boundaries were retained at the

1977 parameters unless specific boundary changes were made under the statutory redesignation

procedures under 1 164 of the Act.

pollution. To date, no State or Indian

tribe has 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

set minimum program requirements for

States to follow in Rreparing, adopting,

and submitting a P9D program for

inclusion as part of the required SIP

pursuant to Section 110(c) of the Act. At

40 CFR 52.21, 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 of an

approved State PSD program, and for

areas such as Indian Lands and Outer

Continental Shelf areas that are outside

of the jurisdiction of individual States.

B. Proposal of PM-lO Increments

On July 1, 1987, the EPA revised the

NAAQS for PM to replace the TSP

indicator with the PM-10 indicator (52

FR 24634). In the same Federal Register,

EPA adopted various final regulations to

implement the revised standards. These

regulations, in part, added PM-10 to the

PSD regulations to reflect its status as a

newly-regulated form of PM.

Consequently, PM-10 emissions became

subject to consideration for applying

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 TSP remained the ambient

Indicator of PM for determining the

amount of significant deterioration of air

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

of Section 166(a) of the Act which

provides that "[in the case of pollutants

which NAAQS are promulgated after

the date of enactment of this part, [the

Administrator] shall promulgate such

regulations [to prevent significant

deterioration of air quality]." Thus, EPA

determined that with the promulgation

of the NAAQS for PM using the new

PM-10 indicator, it had authority under

Section 166 of the Act to promulgate

new PM increments also measured in

terms of PM-10.

C. The 1990 Amendments

A new Section 166(f) to part C of the

Act specifically authorizes EPA to

31623

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31624 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 of equal

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) of the amended Act,

certain areas were designated by

operation of law as nonattainment,

effective upon enactment of the 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 of part D of title I of the

Act are applicable to major new and

modified stationary sources located in

such areas. 7

6 While the statutory provision stipulates that the

existing TSP increments remain in effect at least

until the new PM-10 increments are promulgated,

it is EPA's intent to require that the TSP increments

remain in effect until the PM-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 of the

PSD program for PM will continue without

interruption while the indicator used to measure increment consumption switches from TSP to PM10.

' The 1990 Amendments also added Section

189(e), which addresses requirements for major

sources of PM-10 precursors in PM-10

nonattainment areas. Section 189(e) states: "The

control requirements * * for major stationary sources of PM-10 shall also apply to major sources

of PM-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 the treatment of PM-10

precursors in the General Preamble (see 57 FR

13498, at p. 13541, April 18 1992). Additional

guidance will be provided in a forthcoming notice

of proposed 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 issue further;

III. Discussion of Final Rule and

Comments

A. Legal Authority

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 of a specific indicator, EPA

reasoned that Congress' knowledge that

TSP was the indicator for the PM

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

of the PM NAAQS. Rather, EPA decided

that it must promulgate new PM

increments, reflecting an equivalent

amount of air quality protection but

expressed in terms of the new PM-10

indicator.8

In the proposal, EPA took the position

that Section 166(a) of the 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 of NAAQS 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

0 The decision Notural Resources Defense Coun.

v. EPA. 902 F.2d 962 (DC Cir., 1990) considered the

issue of whether 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 to reflect the

new PM-10 indicator.

"Simply changing the measurement reference

from TSP to PM-10 while maintaining the same

numbers * * * would dramatically relax the PSD

restrictions on particulate matter since the TSP

indicator is a much more inclusive measure of

pollutants * * *. It would be wholly irrational for

Congress to set forth specific numbers of particulate

matter increments and yet authorize a choice of

indicators which radically alters the numbers'

significance and therefore ultimately how much

particulate matter may be emitted. Congress has

plainly expressed an intent to allow a certain

quantum of PM 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 existing TSP

increments set forth in Section 163 of

the Act. However, EPA determined that

this would be burdensome and

unnecessary even during a transition

period. As a result, EPA proposed to

replace the TSP increments with the

PM-10 increments.

2. Public Comments

A few commenters challenged EPA's

overall conclusion that the Act as it

stood at the time of the 1989 proposal

allowed EPA to promulgate increments

based on the new PM-10 indicator, and

phase out use of the TSP indicator. For

instance, one commenter argued that

Section 166 "by its clear terms" applies

only to pollutants for which 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 of PM-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 the United

States." However, most commenters

agreed with EPA's conclusion that the

existing statutory scheme allowed for

the substitution of the 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 of the

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 of this 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 retain the TSP increments

until the new Increments are

implemented, Congress also clearly

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Indicated that EPA need not maintain a

two-increment system for PM. In short,

the Act itself now contradicts any

assertion that EPA is without power to

adopt PM-10 increments or that the TSP

increments must be retained.

Based on this grant of authority, EPA

today is promulgating new PM-10

increments for Class I, I1, and m areas,

and, as described more fully below, Is

eliminating from the PSD regulations

the existing TSP increments.

B. Selection of the Equivalence

Approach

1. Background

In its 1989 proposal, EPA described

two approaches for establishing PM-10

increments that, in accordance with

section 166(d) of the Act, would be "at

least as effective as the 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 for calculating new PM10 increments, thereby retaining

roughly the same limitations on future

deterioration of air 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 to the PM-10

NAAQS which bore the same

percentage relationship as the 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 of the TSP

NAAQS, the Class II increments for PM10 are calculated as 25 percent of the

PM-10 NAAQS.

The EPA believed that the general

equivalence of the increments resulting

from either approach would satisfy the

requirements of section 166(d) of the

Act because both sets of increments

would be expressed as numerical

measures and could be Implemented

similarly to the statutory increments

which they were to replace. Also, both

sets of increments would provide clean

areas of the country with protection

against significant deterioration of air

quality, assuming that all existing

baseline dates and baseline 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 belief that 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 (rather than

supplement) the existing section 163

increments for PM. A more detailed

account of this rationale can be found in

EPA's 1989 proposal (54 FR 41221-

41225).

2. Public Comments

While several commenters supported

the "equivalent to statutory increments"

approach, most commenters supported

the "percentage of NAAQS" a pproach.

Only five commenters favored the "equivalent to statutory increments"

approach in whole or in part. A number

of commenters 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 which EPA 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 of Equivalent Numerical

Levels."

Commenters favoring the "percentage

of NAAQS" 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) are based on percentages of the

appropriate NAAQS concentrations.

Two commenters supported the "percentage of NAAQS" 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-10 NAAQS 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 of the Act as PM-10

increments. Within this group were two

commenters who favored the "percentage of NAAQS" 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 of PM-10,

without changing their numerical

values.

One commenter recommended that

EPA not only retain the statutory

increments as TSP-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 as to how to resolve the

problem. One of the commenters

supported the retention of the existing

increments expressed as TSP

concentrations. Another argued that

EPA should adopt PM increments based

on an indicator measuring fine particles

(PM-2.5) (i.e., particles with a diameter

of less 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 I areas.

3. Decision and Response to Comments

The EPA is today promulgating the

PM-10 increments based on the

,"equivalent to statutory increments"

approach as originally proposed. This

decision is largely based on the reasons

set forth in EPA's 1989 proposal, and

upon the expression of congressional

9

1t should be noted that for the annual averaging

period the "percentage of NAAQS" approach yields 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-

hour averaging period, which tends to be the more critical period for measuring point source ambient

impacts, the former approach yields higher

nmerical increments (e.g.. Class U1-37 Idm3 vs 30

p/M').

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intent contained in the Act under new

section 166(f). The EPA believes that

this new section establishes a clear

directive for EPA to follow the path laid

out by EPA in 1989 for the development

of equivalent increments for PM

measured as PM-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 of PM-10 that would ensure "equal stringency in effect." Arguably, if

Congress had Intended 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 for Congress,

itself, to replace the existing statutory

increments for particulate matter with

PM-10 increments calculated as a

percentage of the PM-10 NAAQS.

In response to those commenters who

stated that the Class I PM-10 increments

should be set at levels which provide

protection against welfare effects and

visibility impairment, particularly in

Class I areas, EPA agrees only In a

general sense. While it is true that

Conrss set the Class I increments at

levels which allow only a relatively

small increase in the ambient

concentration of a pollutant, there is no

evidence that Congress adopted

increments that would ensure specific

levels of welfare and visibility

protection at each Class I area

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

of deterioration In air quality that varies

from area to area depending upon the

baseline concentration of pollution for

such area.' 0 Under this system, based on

the PSD increments alone, two areas

with significantly different baseline

concentrations of a pollutant (yet both

within the limits of the NAAQS), and

having resources that are significantly

different in terms of their sensitivity to

air pollution, could in theory be allowed

to experience the same increase in

ambient levels of pollution. Thus, the

Class I increments are designed to

protect an area from large adverse

changes in air quality, but do not

provide an absolute pollutant

1

0The Act sets forth a defnition of 'baseline

concentration" which is key to the way in which

the increments am implemanted Isection 169(4)L

Basically. the baseline concmtration Is the ambien

concentration of a pollutant which exists at the time

of the first complete application for a PSD permit

in an attainmemt ares. On such date the applicable

baseline date is establIshed and the baseline

concentration is defined from which sipificeA

deterioration of air quality is henc measured.

concentration ceiling that is grounded .

in the air pollution sensitivities of the

various Class I areas.

The Act's main tool for protecting

Class I areas are provisions specifically

addressing the protection of "air quality

related values" (including visibility) in

such areas (see section 165(d) of the Act;

see also, e.g., Hadson Power 14-Buena

Vista, PSD Appeal Nos. 92-3, 92-4 and

92-5 (Remand Order, October 5, 19921.

Congress established the concept of air

quality related values to enable the

identification and protection of specific

ecologically-based attributes contained

within any particular Class I area.

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 be issued

if the Federal Land Manager (FLM)

demonstrates to the satisfaction of the

State that the emissions from such

facility will have an adverse impact on

the air quality-related values (including

visibility) of such 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 if the owner or operator

demonstrates to the satisfaction of the

FLM that the emissions will not have

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 an annual average basis. Short-term

increments were deemed necessary to

protect, among other things, the

environment of Class I areas against

"chronic low levels of pollution or from

repeated short-term peaks of pollution

at levels below the minimum Federal

standards." 1

2 The EPA believes that the

levels of the 24-hour PM-10 increments

for Class I areas will provide general

protection against visibility impairment

I IDuring the floor debate of Senate bill 252 (S.

252), Senator Muskie indicated that the Class I

increments. as contained in S. 252. were established ..solely as a means of determining where the burden

of proof should lie as to adverse impact on air

quality values 1 * (The incremental do not. in

any way. establish a final basis for approval or disapproval of a permit applicaton." Committee on Environment and Public Works, 95th Cong.. 2nd

Seas.. A Legislative History of the Clan Air Act

Amendments of 19" (Vol. 3) at 723-726 (1978.

1

2Tib committee report on the House of

Representatives bill 2161 (H.R.211) states that

"Iellimination of the 24-hour and 3-hour standards

would substantially undermine the public health

and welfare protections built into the committee

proposaL" Te committee indicated Its concrn that

the short-term increments were of perticular

importance for protectinS visibility in aeas such as

the Grand Canyon. Yellowstone and other national

parks end national wilderness areas. Legislative

History (Vol 4) pp. 353 and 2637.

and other welfare-related impacts In the

same manner as did the TSP increments

which they replace. However, specific

protection of any given Class I area is

intended to be provided by the air

quality related values as defined for the

particular area of concern.

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 of visibility in Class I areas.

Moreover, section 169B, added by the

1990 Amendments, calls upon EPA to

assess the level of visibility that will

remain following implementation of the

other provisions of the 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. Development of Equivalent

Numerical Levels.

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/

NSR permits 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 out to establish equivalent levels

for the Class I and Class H Increments.

In each case, two important steps were

involved in the developmental process.

First, the TSP levels were converted to

equivalent PM-10 levels by comparing

the ambient TSP impacts of all sources

in the data base against their estimated

PM-10 impacts, based on the 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 the PM-10 increments

proposal notice (54 FR 41218, pp.

13The PM which sources emit is comprised of

particles having a range of sizes. The PM-10/PM

emission ratio, which was of interest for this

particular rulemaking, reflects the relative amount

of PM-1O vs. the amount of total particulate emitted

by a source. For any given source, the PM-IC/PM

ratio will depend upon the specific emission unit(s)

end control device (and control efficiency)

associated with that unit. A necessary pert of EPA's

analysis, therefor, was the Identification of the

unique emission tmit.control device combinations

contained In the NSR dat base.

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41223-41225) as well as in a technical

report entitled "Technical Report -

Equivalency of Alternative 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 of a PM-10 value

from a range of "equivalent" increments

by comparing the TSP vs. PM-10

impacts of each of the 249 PM sources

in the NSR data base. In principle, for

any source, the equivalent PM-10

increment is simply the product of the

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 of TSP

increment consumed along with the

amount of PM-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 of sources 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 of TSP and PM-10

increment consumption for the entire

sample PSD source population.

For the Class I increments,

considerably less source data were

available because relatively few major

sources were found to be constructed in

the vicinity of Class I areas. For this

reason, in selecting equivalent Class I

increments EPA did not attempt to

compare the percentages of TSP

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 H PM10 increments, since all of the statutory

Class I increments are levels which are

twice the Class l1 increments levels. 14

The equivalent numerical levels of the

PM-10 increments initially bore the

same deterministic form as the statutory

TSP increments, and were stated as

'

4 For example, Congress set the annual Class U

Increments for PM at 19 Ag/m 3 (25 percent of the

annual PM NAAQS), and the Class U1 increments for

PM at 37 pg/m3 (50 percent of the annual PM

NAAQS).

geometric mean values as well.15 In

contrast, the PM-10 NAAQS are

expressed in a statistical form, with the

annual standards stated as arithmetic

mean values. ie In order for the PM-10

increments to be completely consistent

with the form of the 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, the PM-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 the technical analyses

and conversion procedures used to

establish the equivalent numerical

levels.

Several of the commenters expressed

general concern about the overall

adequacy of the NSR data base which

EPA used to develop source-specific

estimates of PM-10 emissions and PM10 increments impacts. The

commenters' concerns focused on both

the quantity and quality of the

information in the data base. One of

these commenters questioned the

completeness and accuracy of the

information contained in the individual

ermit applications from which the data

ase was derived. This commenter

complained that the use of only 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

"'The term "deterministic" describes the method

by which attainment of a particular standard or Increment is determined. Attainment of a deterministic standard or increment considers the

number of exceedances that have occurred, or will occur (based upon modeling predictions), in a single year independently from other years of data.

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 of a statistical standard considers

the number of exceedances that have occurred, or will occur (based on modeling), on average over a number of consecutive years. For example, a 24-

hour statistical standard is attained when the

expected number of exceedances of the 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 not take 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 of PM-10

emissions for sources in the data base

.was also the subject of several

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 of TSP

for major 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 of PM-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 of the

means of calculating 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 of PM-10/

TSP."

One commenter went to great lengths

to describe "a basic fallacy" in EPA's

technical method, based on the

modeling of PM 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 of the ambient sampling

method for collecting TSP is

significantly different from various instack sampling methods for measuring

emissions of PM. 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

mining industry 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 smaller than 10 micrometers, has

little or no human health or

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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 the arid Western 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. In the

view of this 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, the commenter

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 the cost and complexity of the

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 of the types of

sources and PM emissions controls that

can be expected to apply for PSD

permits and consume PM-10

increments throughout the Nation. The

249 sources from which information on

PM was taken 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 of any better

data that could have been used to carry

out the analysis. The fact that the data base is limited

to permits issued between 1977 and

1984 does not render the information as

inadequate for establishing equivalent

PM-10 increments. It does not

automatically follow, as a few

commenters concluded, that sources

with improved control efficiencies (and

thereby higher PM-10/PM emissions

ratios) will have a more difficult time

complying with the 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 of PM-10

emitted by a particular source.

The comments concerning the alleged

conservative nature of models used

"during the early stages of model

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 of PM

in the NSR data base-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 of TSP

and PM-10 increment (based on several

trial increment levels) consumption

occurring for each PM source in the data

base. Each of the resulting PM-la

increment consumption curves was

compared to the TSP increments

consumption curve to determine which

one best approximated the same amount

of overall PM-10 increment

consumption. In the event that the

particular model used by a PSD

applicant overestimated the source's

TSP impact, then (1) the amount of TSP

increment consumed also would have

been overestimated, and (2) the

corresponding PM-10 impact and

amount of PM-10 increment consumed

would have been equally overestimated.

Consequently, all of the plotted curves

would reflect equal overestimations.

Since all curves (TSP and PM-10)

would have been affected similarly,

identifying the equivalent curve should

not be affected by any overestimations.

With respect to commenters' criticism

of the uncertainties associated with the

conversion of PM emissions to PM-10

emissions, EPA believes that it took 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 for consistency 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 not technically possible.

However, EPA believes that the

Increment levels selected provide the

best "fit" relative to the representative

sample of PSD sources included in the

analysis.

As was reported in the preamble to

the proposal, some sources consume

more of the available increments under

the equivalent Class II PM-10

increments, and some consume less.

There was essentially no difference in

the percentage of increments consumed

(i.e., less than 5 percent difference) for

about 91 percent of the 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 of these types such

that those emissions would not cause

violations of the new PM-10

increments.

In the case of the Class I increments,

EPA found for a few sources that the

selected PM-10 increments levels

would result in a greater portion of PM10 increments being consumed than of

TSP increments. However, in no case

would a PM-10 increments violation be

predicted.

The commenters who criticized EPA's

use of PM emissions data (and modeled

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, if ever, used to determine

increments consumption. There are

several reasons for this fact. First, the

predicted air quality impacts of the

proposed new or modified 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 of stack heights which exceed

good engineering practice. Accordingly,

calculations of increments consumption

have typically been accomplished by

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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 of the PM-10

increments. This issue was raised

previously when EPA proposed the PM10 NAAQS. and EPA responded at that

time that a size-specific, rather than a

chemical-specific, indicator should be

used in setting NAAQS for PM. 17 The

EPA continues to believe that particle size is of primary concern. Moreoveri a

two-tiered system for measuring air

quality deterioration would be

inappropriate in light of the fact that no

such system exists for the NAAQS. It

should be noted, however, that the PSD

requirements do provide for the

exclusion of certain 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 of the

PM-10 increments, EPA finds no

compelling reason within the

commenter's argument to adjust the

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 are expressed as such.

The commenter's concern that EPA's

proposed deterministic form for the

PM-10 increments would require

duplicative and redundant

recordkeeping and compliance evaluations is unfounded because of the

different data input typically required for the increments and NAAQS analysis. That is, both the inventory of sources

and the source emissions input data

tend to differ because of the differing

nature of the two types of analyses. The

emissions inventory needed to perform

an increments analysis includes only those sources whose emissions consume

a portion of the increments (as opposed

to the baseline concentration) and the

emissions input data reflects the actual

'?In its original assessment of this Issue. EPA

examined available scientific information and

concluded that the indicator for the primary standard should include those particles 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 the proposal notice,

the EPA's decision to convert the annual

increments to arithmetic mean values

was based largely on practical

considerations. The calculation of an

arithmetic mean value is a more

straightforward method which is

compatible with current modeling

computations. The commenter correctly pointed out that 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 for the difference.

D. Implementation Issues

1. Source Applicability

a. Background. The EPA did not

propose any changes with respect to the

criteria for determining whether a

stationary source of PM is subject to

PSD review. That is, In continuing the

requirements of the existing PSD

regulations, consideration will be given

to both "PM emissions" 18 and "PM-10

emissions" in determining PSD

applicability. Under the existing

regulations, a new stationary source is

subject to PSD for PM if it has the

potential to emit any pollutant in major

amounts and would emit either PM

emissions or PM-10 emissions in "significant" amounts [§ 52.21(i)(2)). An

existing major stationary source is

subject to PSD as a major modification

of PM if its proposed net emissions

increase would result in significant

amounts of either PM emissions or PM10 emissions.

Significant emissions of PM would

continue to be defined as either 25 tons

per year (tpy) or more of PM emissions,

or 15 tpy or more of PM-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 for a source to install BACT applies independently to either form of PM

lathe term "particulate matter emissions" is

defined as all finely divided solid or liquid

material, other than uncombined water. emitted to the ambient air as measured by applicable reference

methods, or an equivalent or alternative method.

specified by EPA or by a test method in an approved SIP 140 CFR 51.1001.

when it will be emitted in significant

amounts.

b. Public Comments. 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's prior elimination of the TSP

NAAQS) warranted a source

applicability test based only on PM-10

emissions. The general response of these

commenters was that "TSP" should be

totally eliminated as a parameter of

concern in all portions of the PSD rules.

c. Decision and Response to

Comments. After careful review of the

original proposal and the EPA's

rationale for a dual applicability test for

PM, EPA has determined that it is

necessary to retain the requirements, as

proposed, at this time. As indicated in

the proposal, PM emissions continue to

be regulated under a variety of section

Ill new source performance standards

(NSPS) (40 CFR part 60). Even though

EPA has now eliminated TSP as the

ambient indicator for measuring

compliance with both the PM NAAQS

and the PM increments, in-stack

measurements of total particulate

emissions continue to serve as the

specific basis for evaluating compliance

under the NSPS. Thus, PM emissions

must be regarded as a pollutant "subject

to regulation under the Act" and,

therefore, subject to PSD review

[§ 52.21(b)(23)(i)].

2. Geographic Applicability

a. Background. In the October 5, 1989

Federal Register proposal notice, EPA

announced that the new increments

generally would apply everywhere

under a special system of PSD area

designations for PM-10 (54 FR 41225-

41226). This approach to applying the

PM-10 increments differed from the

existing geographic applicability

roVisions for the TSP increments

which apply in areas designated as

attainment or unclassified for TSP

pursuant to section 107(d) of the 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 for that pollutant. In accordance with the proposed

geographic applicability format for PM10, EPA proposed two specific actions.

The first was to identify the surrogate

area designations for PM-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 for each

criteria pollutant. The second action

involved revising the definitions of

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"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) of the Act and, thus, would not

have provided a means for identifying

baseline areas and baseline dates for

PM-10.

b. Public Comments. Only one

commenter expressed any objection to

EPA's proposed geographic applicability

concept. That commenter questioned

EPA's plan to require the

implementation of the new PM-10

increments in areas designated

nonattainment for PM-10 NAAQS.

c. Decision and Response 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 of the 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 of the 1990

Amendments, it is no longer necessary

for EPA to consider special geographic

applicability provisions for the PM-10

increments.

By operation of law upon enactment

of the 1990 Amendments certain areas

were designated nonattainment for PM10 [section 107(d)(4)(8) of the amended

Act; also 56 FR 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 of the 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)

of the 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

of the State designated as attainment or

unclassifiable for PM-10 (section 161).

Accordingly, the PM-10 Increments will

not apply in areas designated

nonattainment for PM-10,

As a result of the new area

designation requirements for PM-10

under revised section 107 of the 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-10 as they would

have been listed in subchapter C of 40

CFR part 81. These changes are no

longer necessary because attainment

status designations pursuant to section

107(d) of the Act are now required for

PM-10. It should be 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 of TSP Baseline Dates and

Baseline Areas

a. Background. The equivalent

increments approach proposed by EPA

included the retention of the 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

for TSP, would be considered the

baseline date for PM-10, even if the 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 of the PM-10

increments, the date would be set in the

future by the first PSD application for a

major new or modified stationary source

having the potential to emit significant

amounts (15 tpy) of PM-10.

b. Public Comments. Six commenters

specifically objected to EPA's proposed

retention of the 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-10 increments using irrelevant TSP

baseline dates and areas.

Many of these commenters argued

that section 166 of the Act applies only

to pollutants for which EPA establishes

new NAAQS. Thus, if PM-10 is a new

pollutant for increment-setting purposes

under section 166 of the Act, prior

consumption of the TSP-based

increments is irrelevant and illegal.

Several commenters alluded to EPA's

promulgation of NO2 Increments, 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 of the 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 of industrial

sources, varying PM-10/TSP ratios, and

problems tracking major modifications

and minor source contributions of PM10 over the last 15 years.

Two commenters introduced

implementation issues which they .considered to be justification for starting

over with new PM-10 baseline dates.

One of these commenters stated that

retention of the TSP baselines would

penalize those areas which came into

compliance with the TSP NAAQS, since

those areas likely have already

consumed a portion of the available

increments and "would not receive 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 of the existing TSP minor

source baseline dates even where it

could be shown that the source

triggering the baseline date would not

have done so based on potential PM-10

emissions.

c. Decision and Response to

Comments. The EPA continues to

believe that it is appropriate to retain

the original TSP baseline dates and

baseline areas as part of the program for

implementing the PM-10 increments.

The PSD program established by

Congress under the 1977 Act was

designed to prevent significant

deterioration of air quality for the.

pollutant PM-Congress did not

designate what indicator was to be used.

The establishment of a new indicator for

PM (both for the NAAQS and

increments) does not mean that EPA

must ignore all increments consumption

of PM which has occurred to date.

Moreover, this would ignore Congress'

underlying intent to prevent the

deterioration of local air quality due to

increased PM emissions. Ambient PM10, a component of TSP, has always

been counted toward measurements

used to determine compliance with the

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TSP NAAQS. It would be difficult to

argue that amounts of PM-10 emitted

prior to the promulgation of the PM-10

NAAQS should not be counted for

determining compliance with such

standard simply because they were

previously included as a measure 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

not part of the measurement for

determining compliance with the

revised NAAQS for PM. The statutory

framework certainly ties the NAAQS 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 for preserving the PSD

system for PM established by Congress.

The addition of new section 166(0

under the 1990 Amendments supports

EPA's final decision. Congress clearly

intended to preserve the current PSD

process for PM when it provided for

"[siuch substituted maximum allowable

increases * * of equal stringency in

effect as those specified in the

provisions for which they are

substituted." Moreover, Congress

instructed EPA to retain the TSP

increments until it promulgated the new

PM-10 increments, thereby ensuring

there would be no gap in the protection

of air quality with respect to PM.

The EPA does not agree 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 of the

appropriate sources whose emissions

consume increments. It Is the

responsibility of the applicant (under

the direction of the 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 of a

previous TSP increments assessment

and determine the amount of PM-10

increments consumed based on the local

ambient PM-1/TSP ratio. Increments

consumption is based 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 (44 FR 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 that areas

which were previously attainment for

TSP likely will have already consumed

some portion of the available PM-10

increments. Generally, the fact that the

amount of available increments has

decreased is indicative of the economic

growth which has occurred in the PSD

area.

In contrast, areas which were

previously nonattainment for TSP did

not have the same growth opportunities

because of the 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 of very 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 for PM. Also, it

should not be assumed that previous

nonattainment areas for TSP, which are

now unclassifiable for PM-10, will

always have the full amount of PM-10

increments available. That is, in areas

where the ambient concentrations in the

area are just below the PM-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 of potential 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 it would

inappropriate to retain a TSP minor

source baseline date when it can be

shown that the PM-10 emissions from

the source triggering the baseline date

were de minimis. In arriving at this

conclusion, EPA considered existing

policy concerning the triggering of the

minor source baseline date. That policy,

in part, provides that a minor source

baseline date will no longer be

considered set if the 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 be considered

significant closely follows the

circumstances under which a permit

rescission would enable the minor

source baseline date to be changed.

Section 169(4) of the Act establishes the

submittal of a complete application as

the baseline triggering mechanism on a

pollutant-specific basis. In recognition

of the pollutant-specific nature of the

minor source baseline date, the PSD

regulations stipulate that the minor

source baseline date is established 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 that pollutant in a

significant amount. The EPA has

concluded that, in terms of the effect on

the minor baseline date, a source of PM

whose emissions are no longer

considered significant because of a

regulatory change in the applicable

pollutant indicator should be treated the

same as a source that is no longer

considered major. In order to implement this new

policy, EPA is modifying it's proposed

revision of the definition of "minor

source baseline date" at

§ 52.21(b)(14)(iv) to indicate that the

Administrator will no longer consider

the minor source baseline date to be

triggered by a particular source when it

can be shown, to the satisfaction of the

Administrator, that such source did not

have the potential to emit significant

amounts of PM-10. Any State having an

EPA-approvd PSD program in its SIP

may adopt a similar policy if it wishes

to do so [new § 51.166(14)(iv)]. It should

be noted, however, for purposes of

determining the amount of available

PM-10 increments, the source which

triggered the original minor source

baseline date still consumes PM-10

1

9

1t is EPA's longstanding policy to require

generally that once a minor baseline date is set by

a particular source via the submittal of a complete PSD permit application, such date will remain in

effect even when the application is voluntarily

withdrawn or the permit is denied. The policy as originally announced contained an exception,

however, for any source originally defined as major

under the June 1978 PSD regulations, but which was no longer considered major as a result of

regulatory changes promulgated on August 7,1980

(FR 52676, August 7,1980, p. 52717).

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increments, since it is a major stationary

source whose PM-10 emissions have

been increased after August 7, 1977 (the

major source baseline date for PM) as a

result of the construction or

modification of the facility

[§ 52.21(b)(13)(ii)(a)].

4. Implementation Date

a. Background. The EPA announced

that the 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 of the

Act. As discussed, section 166(b)

specifically provides that new

increments promulgated by EPA must

be part of an approved State PSD

program not later than 25 months from

their date of promulgation. 20 In order to

apply the same implementation

schedule to the new increments in both

the State and Federal PSD programs,

EPA proposed that the new increments

would become effective 1 year from

their date of promulgation in § 51.166,

and 25 months from their date 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 of the new increments

under the Federal PSD program could

have begun I year from the date of

promulgation in § 52.21.

b. Public Comments. 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 of the

regulations should not precede the

publication and distribution of

guidelines * * * to determine the

increase or decrease of area source

emissions from the baseline date."

c. Decision and Response to

Comments. The EPA has given further

consideration to the proposed

implementation schedule and has

concluded that implementation of the

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

20n addition to the 1-year delay in the effective

date of any new increments which EPA

promulgates pursuant to section 166 of the Act,

section 166(b) provides each State with 9 months

to revise their current PSD plan and to submit it to

EPA for approval. The EPA then has 4 months to

review and issue a determination on the approval of the revised plan.

become effective I year from the date of

promulgation, and (2) State PSD

programs be allowed 25 months from

the date of promulgation to implement

any new PSD increments. The EPA has

determined that, in the case of the 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 the best Interests of the 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, since the

implementation of the PM--10

increments involves the switching of

indicators rather than the

commencement of a completely new set

of increments requirements (as was the

case with the new NO2 increments), no

apparent inequity results from the early

implementation of the PM-10

increments in one State as compared to

another State.

Consequently, EPA is today

announcing that the PM-10 increments

promulgated under the Federal PSD

program in § 52.21 will become effective

12 months from today. The EPA or its

delegated State program will begin

implementation of the increments at

that time. 21 The 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 of the

effective date could face sanctions and

Federal implementation of that portion

of the State's PSD permitting plan.

5. Grandfathering Provisions

a. Background. As part of the

transition process for phasing in the

new PM-la increments, the EPA

proposed to exempt certain PSD

applicants from the new requirements

for a PM-10 increments analysis.

Specifically, EPA proposed to add

grandfathering provisions to the PSD

21States implementing an NSR program through

a delegation of § 52.21 from EPA should, when

necessary, modify that delegation agreement over the next 12 months to reflect the changes to that

regulation promulgated today. If States fail to

change the delegation agreement, EPA will become

the permitting authority.

regulations under both part 51 and part

52, which would exempt from the PM10 increments analysis any PSD

application for which a final permit

determination has not yet been made

when (1) the application, including a

TSP increments analysis, is submitted

before the implementation date of the

new PM-10 increments, and (2) the

application is considered complete

based on the existing requirements on

the date of submittal. 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 of ambient PM-10

monitoring data).

b. Public Comments. Two commenters

responded to EPA's proposed

grandfathering provisions. While both

commenters supported the

grandfathering concept, one requested

that applicability of the proposed

exemption be broadened to include any

PSD applicant for which a TSP

increments analysis has been

completed, even if the remainder of the

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 of the

application."

c. Decision and Response 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 of a complete PSD

application, instead of the date of a

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 of the application may be

incomplete, simply to "lock in" the

original increments analysis prior to the

point where 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 in the

permit application. In fact, the

increments analysis is dependent upon

the emissions and other source

information contained elsewhere in the

application.

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Also, EPA does not intend to disallow

the grandfathering of a proposed project

from the new PM-10 increments

requirements merely because an

unrelated or minor element of the

overall application may be

"incomplete." Nor does EPA believe

that States would do so. A completeness

determination generally acknowledges

the receipt of an application containing

sufficient information to enable the

reviewing agency to begin the process of

reviewing the contents of the

application, but does not preclude the

agency from requesting additional

information which may be necessary as

the review progresses. Finally, the new

increments will not become effective for

I year after their promulgation in the

case of the part 52 PSD regulations

(generally longer for SIP-approved PSD

programs). Applicants for PSD permits

will have ample time to plan the

submittal of their applications, knowing

when the effective date will occur.

6. Exclusions From Increments

Consumption

a. Background. Section 163(c)(1)(C) of

the Act provides that any ;tate with an

EPA-approved PSD plan may "issue

orders or promulgate rules" to exclude

concentrations of PM caused by "construction or other temporary

emissions-related activities" from

increments consumption. The owner

must submit an order of rule to the

Administrator, and the Administrator

must determine that the order of rule is

in compliance with the subsection. In

its PM-10 increments proposal, EPA

indicated it would consider any specific

exclusion for PM-10 that a State may

wish to add when it revises its SIP to

adopt PM-10 increments, provided such

exclusion would not result in

permanent or long-term deterioration of

air quality. "Prescribed burning" was

given as an example of an activity

which may oftentimes be regarded as'

temporary, but could also be considered

to have longer lasting (intermittent)

effects under certain circumstances (54

FR 41228).

In order to 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 of specific mitigation measures;

(2) what, if any, accountability measures

should be required regarding the

temporary nature of air quality

deterioration resulting from excluded

activities; and (3) whether excluded

activities should be "coordinated" or

"scheduled" when occurring in a

common air shed to minimize the

ambient impact from all excluded

activities on a given day.

Finally, EPA pointed out that, while

certain exclusions from increments

consixmption are available to any State

with an approved SIP, such exclusions

should not be 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 by EPA

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 of the exclusion

provisions under the Federal PSD

program while States were developing

their own initial PSD program (45 FR

52676, August 7, 1980; p. 52677).

After May 7, 1981, exclusions were to

be no longer applicable under the

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 of the 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. Public Comments. 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 of PM-10 emissions

caused by prescribed burning. The

commenters' support was based on

several factors including: Prescribed

burning is a temporary activity, it

typically reduces the overall amount of

PM that might otherwise occur from

wildfires, and it serves an essential

ecological function. Two of the

commenters recommended that the

exclusion of prescribed burning

activities should be contingent upon

such fires being conducted in

accordance with a prescribed fire plan

and best management practices. Another

commenter expressed concern that the

proposed rule leaves to the States'

discretion whether or not emissions

from prescribed fire will consume

increments.

One commenter cautioned that EPA

lacked the authority to impose

conditions on the required approval of

exclusions from increments

consumption adopted by the States.

This commenter noted that the Act

directs the Administrator only to

determine whether a State's exclusion is

in compliance with the provisions of

§ 163 of the Act.

c. Decision and Response to

Comments. The EPA supports the

concept of allowing States to exclude

emissions caused by temporary

prescribed burning activities from the

PM-10 increments. It also agrees that

there are important considerations to be

made as to how and 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 itself is

of a 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 of time. The Act

provides that "construction and other

temporary emissions-related activities"

shall be excluded from increments

consumption pursuant to a State rule or

order upon which the public has been

afforded an oportunity to 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 for this 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 after August 7, 1980, unless a

SIP revision meeting the requirements

of 40 CFR 51.166 has been submitted to

the Administrator.

The original purpose of this provision

was to restrict the implementation of the

exclusion provisions under EPA'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 of Significant

Deterioration Monitoring

a. Background. The PSD regulations

require that any application for a permit

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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 for PM-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 of the TSP

increments. Accordingly, the significant

ambient concentration for TSP 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. Public Comments. Only a few

comments were received concerning

this issue. Those who responded agreed

that the ambient data requirements for

TSP should be eliminated once EPA

promulgates new PM-10 increments

replacing the existing TSP increments.

One commenter went a step further

stating that EPA 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 for which 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 not be exceeded." This

commenter thus recommended that,

pending refinement of existing 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. Decision and Response to

Comments. Consistent with its proposed

action, EPA is today deleting the

significant ambient concentration for

TSP from paragraph (i)(8)(i) in both the

part 52 PSD regulations and the part 51

SIP requirements for PSD. The EPA will

no longer require PSD applicants filing

for a Federal PSD permit to submit

preapplication monitoring data for TSP,

nor will EPA require postconstruction

TSP data. With the replacement of the

TSP increments, EPA considers only

PM-1 to be regulated with respect to

ambient indicators for PM. Thus, only

ambient PM-10 data will be required

where applicable. States will not be required to request

ambient TSP data either. However, if a

State wishes to continue requiring the

submittal of such data, it has the

authority to do so. Some States continue

to define ambient air quality standards

in terms of TSP (in addition to the

national standards based on PM-10),

and may elect to continue requiring the

submittal and evaluation of ambient

TSP data to determine compliance with

such standards.

Concerning the comment that EPA

incorrectly required the submittal of

ambient TSP data after the date when

the PM-10 NAAQS were promulgated,

EPA wishes to point out that its policy

has been to regard TSP as a noncriteria

pollutant (with PM-10 being the criteria

pollutant) with respect to PM for any

area where the PM-10 NAAQS have

been in effect. Under the PSD

requirements, the submittal of ambient

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 of the PM-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 of the

dispersion model, known as the

Industrial Source Complex Model (ISC),

with AP-42 emissions factors. Section

234 of the 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 of fugitive particulate emissions

om surface coal mines, for purposes of

new source review or for purposes of

demonstrating compliance with the

NAAQS applicable to periods of 24

hours or less, EPA is to assess the

accuracy of such model and emissions

factors. Section 234 further provides

that, in the meantime, States may use

alternative empirical based modeling

approaches, based on guidance

provided by EPA, to determine the

effects on air quality of fugitive

particulate emissions from surface coal

mines.

The EPA is undertaking a joint study

with the mining industry to determine

the ability of EPA's ISC model using

AP-42 emissions factors to accurately

predict short term ambient

concentrations of PM-10 from surface

coal mining activities. Until EPA

completes the study as called for under

section 234, EPA intends to allow

estimates of 24-hour increment impacts

caused by fugitive emissions from

surface coal mines to be made on a caseby-case basis with current EPA

models.22 If such estimates predict

ambient violations of the 24-hour PM10 increments, alternative methods,

including empirical based modeling,

may be applied on a case-by-case basis.

Section 3.2 of EPA'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 of fugitive

particulate emissions from those new or

modified surface coal mines subject to

PSD. 23

Any monitoring data which are used

for purposes of demonstrating the

ambient impacts of surface coal mining

activities should be based on monitors

which are operated in accordance with

EPA regulations and guidelines,

including requirements for quality

assurance for air quality data as

contained in Appendix B of 40 CFR part

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

of available increments within that

baseline area. Consequently, PSD

applicants will be required to determine

the extent to which PM-10 emissions

increases or decreases from area sources

have occurred in the area of the

proposed new source or modification. In

the proposal notice, EPA indicated that

emissions from motor vehicles and

residential wood combustion will have

a greater impact on the PM-la

increments than such emissions had on

the original TSP increments.

22 Section 234 references the use of the ISC model

with AP-42 emissions factors to "determine" the

effect on air quality. This provision does not

prohibit les than finally determinative uses. 2

3 During this Interim 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 or require reasonable assessment tools, so

Ions as the mialmum Federal reqitrements ae satisfied I Wiscondn Publ Intervenor v. Mortler.

liI S.CL. 2470 (1991)).

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b. Public Comments. One commenter

expressed concern about the lack of EPA

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. Decision and Response to

Comments. The kinds of area sources

that will consume PM-lu increments

are essentially the same sources that

have been affecting the TSP increments.

Since EPA's promulgation of PM-10

NAAQS in 1987, EPA has been

reviewing the available PM emissions

factors, including those for certain types

of open 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 of Air 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

is presently developing special guidance

to assist in the calculation of increments

consumption resulting from mobile

source emissions. This guidance began

with a focus on the impacts on the NO2

increments, however, EPA intends to

expand this effort to address the PM-10

increments as well. This and other

forms of PSD increments guidance will

continue to be prepared as needed.

E. Other Issues

1. TSP Area Designations

The replacement of the TSP

increments with PM-10 increments

which operate independently from the

section 107 area designations for TSP

will negate the need for the 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 C of 40 CFR part 81 as each

State replaced the TSP increments with

the new PM-10 increments.

Specifically, EPA stated that the actual

deletion of the 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 not to adopt the

increments on their own, or (3)

approves a State's request for delegation

of PSD responsibility under § 52.21(u).

The EPA received no comments

concerning this particular action. At the

appropriate time, EPA intends to

proceed with the elimination of the TSP

area designations. Generally, the first

TSP area designations to be deleted will

be those in' States where EPA has the

legal responsibility for implementing

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 the TSP designations for a

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. If a State with 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 are revised, EPA will

delete the TSP areas for that State at the

same time that it approves such

delegation of authority. However, the

date on which these events may occur

cannot precede the effective date of the

PM-10 increments in the PSD

regulations under § 52.21.

2. Regulatory Impact Analysis (RIA)

The E.O. 12291 requires EPA to judge

whether a proposed regulation is "major" and therefore subject to the

requirement for a RIA. A regulation is

defined as major if either (1) the net

annualized cost of control (including

capital charges) exceeds $100 million

per year, or (2) firms affected by the

regulation incur a significant (greater

than 5 percent) increase In the price of

goods. Using worst-case assumptions

and conservative costing methods, EPA

analyzed the effects of the 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 not be

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 as a whole."

The EPA disagrees with the

commenter's claim that the analysis was

flawed because it failed to consider

"industry as a whole." The analysis

performed by EPA considered only that

portion of industry which was projected

to be adversely affected by the proposed

rule. The EPA is not obligated to

consider control costs that would be

required independently from the

proposed regulatory requirements.

Under the existing PSD regulations,

each new or modified major stationary

source is already required to apply the

BACT for PM-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

of the PM-10 increments, and the PM

emissions increase did not cause a

violation of the TSP increments.

Therefore, in the analysis performed by

EPA, it was only necessary to consider

the additional control costs which could

be Incurred directly as a result of the

new requirements.

As part of its cost analysis, EPA

initially identified those sources in the

NSR data base that demonstrated

compliance with the TSP increments,

but were estimated to have PM-10 air

quality impacts exceeding the levels of

e PM-10 increments. Next, based on

the number of affected sources in each

source category, EPA projected the

number of new facilities within that

source category that would potentially

exceed the PM-lu Increments in the

fifth year (EPA typically uses a 5-year

timeframe for cost estimates associated

with the RIA). The estimated cost

associated with applying the additional

level of control 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 of the critical values

used to determine whether the

rulemaking constitutes a major action.

Nevertheless, because of the amount of

time that has elapsed since the analysis

was completed, EPA reexamined the

original analysis to determine whether

the assumptions made therein and the

associated dollar values changed

substantially over the period of time

since the analysis was performed. Based

on that reexamination, EPA estimates

that the equipment costs in the report

would increase by roughly 15-20

percent if they were updated to current

dollars. Similarly, annual operating

costs stated in the report could increase

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

by a similar amount. However, this level

of increase would not alter the status of

the rulemaking.

IV. Administrative Requirements

A. Reference Documents

1. Radian Corporation. Technical

Report-Equivalency of Alternative

PM-10 Increments. Prepared for U.S.

EPA. Office of Air Quality Planning and

Standards. Research Triangle Park,

North Carolina. March 1988.

2. Radian Corporation. Cost and

Economic Impact Assessment for PM10 Increment Options. Prepared for U.S.

EPA. Office of Air Quality Planning and

Standards. Research Triangle Park,

North Carolina. April 1988.

3. Shumaker, J. L., Radian Corporation

(1988). Evaluation of Source 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

I TSP 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 for TSP.

Memorandum to John Bachman.

September 1, 1983.

7. Tikvart, Joseph A., U.S. EPA,

Source Receptor Analysis Branch

(1989). Comparison of Model Estimates

for Deterministic vs. Statistical

Standards. Memorandum to Edward J.

Lillis. April 4, 1989.

8. Radian Corporation. PM-10 Area

Sources Paper. Prepared for U.S. EPA.

Office of Air Quality Planning and

Standards. Research Triangle Park,

North Carolina. February 1988.

9. Vatavuk, William, U.S. EPA, Cost

and Economic Impact Section (1983).

Review of Cost and Economic Impact

Assessment for PM-10 Increment

Options. Memorandum to Daniel J.

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 Order 12291)

Under E.O. 12291, EPA must judge

whether a regulation is a "major rule"

and therefore subject to the requirement

for preparation of a RIA. This ruling is

not a major rule because it would result

in none of the adverse economic effects

set forth in section 1 of E.O. 12291 as

grounds for finding a regulation to be

major.

This regulation was submitted to the

Office of Management and Budget

(OMB) for review. Written comments

from OMB to EPA and any EPA

response are included in Docket A-88-

19.

C. Paperwork Reduction Act

Under the Paperwork Reduction Act

(44 U.S.C. 35.01) Federal agencies must

obtain OMB clearance for collection of

information from ten or more nonFederal respondents. This rule does not

contain any information collection

requirements, and so does not require

OMB clearance.

D. Economic Impact Assessment

Section 317 of the Act requires the

Administrator to prepare an economic

Impact assessment for any regulations

tunder part C of title I (relating to PSD

of air quality). An economic impact

assessment was prepared for the

proposed PM-10 increments levels and

also for other alternative levels. The

requirements of this section were

considered in the formulation of the

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. Regulatory Flexibility Act

Certification

Pursuant to the provisions of U.S.C.

605(b), I hereby certify that this rule, if

promulgated, will not have a significant

economic Impact on a substantial

number of small business entities (46 FR

8709). In accordance with the PSD

requirements set forth under part C of

the Act, the preconstruction review

requirements of this rule apply only to

major new and modified stationary

sources of air pollution.

F. Effective Date

These rules are effective June 3, 1994.

List of Subjects

40 CFR Part 51

Administrative practice and

procedure, Air pollution control,

Intergovernmental relations, particulate

matter, Reporting and recordieeplng

requirements.

40 CFR Part 52

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 in the

preamble, part 51, chapter 1, title 40 of

the Code of Federal Regulations, is

amended as follows:

1. The authority citation for part 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) is removed and

reserved; and paragraphs (b)(14)(iv),

(b)(15)(iii), and (i)(12) are added to read

as follows:

§51.166 Prevention of significant

deterioration of air quality. * 0 * * *

(b)" '

(3) * *

(iv) An increase or decrease in actual

emissions of sulfur 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 of maximum allowable

increases remaining available. With

respect to particulate matter, only PM10 emissions can be used to evaluate the

net emissions increase for PM-10. * * * * *

(14)

(iv) Any minor source baseline date

established originally for the TSP

increments shall remain in effect and

shall apply for purposes of determining

the amount of available PM-10

increments, except that the reviewing

authority may rescind any such minor

source baseline date where it can be

shown, to the satisfaction of the

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 of determining the amount of

available PM-10 Increments, except that

such baseline area shall not remain in

effect if the permit authority rescinds

the corresponding minor source

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

baseline date in accordance with

paragraph (b)(14)(iv) of this section. * . * * *

(c)'

Maximum

allowable InPcrease

per cubo Ctae r

a~mi

Particulate matter

PM-10, annual azthmetlc

m ean 4

PM-la. 24-hr maxamm 8

Sulfur dioxide:

Annual athmetic mno .... 2

24-v maximum ................. 5

3-hr maximum ........... 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-hr maximum .................. 512

Nitrogen dioxide:

Annuar'adthmetlc mean .... 25

am III

Pariculate matter:

PM-IO, annual adtmtlc

ma.........o 34

PM-O, 24-hr maximum 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/m 3 of

PM-10, 24-hour average.

(12) The plan may provide 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 of the source or modification

submitted an application for a permit

under the applicable permit program

approved under the Act before the

provisions embodying the maximum

allowable increases for PM-10 took

effect as part of the 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 for TSP

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-hr maximum ................... 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 Code of Federal Regulations, is

amended as follows:

1. The authority citation for part 52

continues to read as follows:

Authority. 42 U.S.C. 7401-7642 as

amended by the Clean Air Act Amendments

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:

1 52.21 Preventlon of significant deterloraton of air quality. *I * * * *

(b)"

(3) * * *

(iv) An increase or decrease in actual

emissions of sulfur dioxide, particulate

matter, or nitrogen oxide, which occurs

before the applicable minor source

baseline date is creditable only if it is

required to be considered in calculating

the amount of maximum allowable

increases remaining available. With

respect to particulate matter, only PM10 emissions can be used to evaluate the

net emissions increase for PM-10. a * * * $

(14) * * *

(iv) Any minor source baseline date

established originally for the TSP

increments shall remain in effect and

shall apply for purposes of determining

the amount of available PM-10

increments, except that the

Administrator shall rescind a minor

source baseline date where it can be

shown, to the satisfaction of the

Administrator, that the emissions

increase from the major stationary

source, or 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 of determining the amount of

available PM-10 increments, except that

such baseline area shall not remain in

effect If the Administrator rescinds the

corresponding minor source baseline

date in accordance with paragraph

(b)(14)(iv) of this section. * * * * a

(c) *

Maximum

allowable InPollutant crease (mkirorams

per cubic

meter)

classI

Particulate matter

PM-1O, annual arithmetic

m oan................... 4

PM-10, 24-hr maximum .... 8

Sulfur dioxide:

Annual adrthmetlc mean .... 2

24-hr maximum ................. 5

3-hr maximum ................... 25

Nitrogen dioxide:

Annual adthmetic mean .... 2.5

Class 1I

Particulate matter

PM-10, annual arithmetic

mean ........... 17

PM-10, 24-hr maximum 30

Sulfur dioxide:

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

31637

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316,38 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 of PM10, 24-hour average; * * * * *

(13) The requirements 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-10 if (i) the owner or

operator of the source or modification

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 with respect to the

maximum allowable increases for TSP

as in effect 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

* * * * *

[FR Doc. 93-12372 Filed 6-2-93; 8:45 am]

BILUNG COOE 660-P

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