12492 Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules

the purposes for which the organization

is authorized to mail at special bulk

third-class rates. However, if the

material contains one or more

advertisements that are not substantially

related, the material is not eligible for

the special rates, unless it is a

publication that meets the content

requirements described in 5.8 and is not

disqualified from using the special bulk

third-class rates under another

provision.

c. Announcements of activities, e.g.,

bake sale, car wash, charity auction,

oratorical contest, are considered

substantially related if substantially all

the work is conducted by the members

or supporters of a qualified organization

without compensation.

d. Advertisements for products and

services, including products and

services offered as prizes or premiums,

are considered substantially related if

the products and services are received

by a qualified organization as gifts or

contributions.

e. An advertisement, promotion, offer,

or subscription order form for a

periodical publication meeting the

eligibility criteria in E211 and published

by one of the types of nonprofit

organizations listed in 2.0 is mailable at

the special bulk third-class rates.

* * * * *

[Renumber existing 5.8 as 5.12,

renumber existing 5.9 as 5.11, and add

new section 5.8 as follows:]

5.8 Periodical Publication Content

Requirements

Advertisements for products and

services in materials that meet the

content requirements for a periodical

publication are mailable at the special

bulk third-class rates. The material

mailed must meet the following

requirements:

a. Have a title. The title must be

printed on the front cover page in a style

and size of type that make it clearly

distinguishable from other information

on the front cover page.

b. Be formed of printed sheets. (It may

not be reproduced by stencil,

mimeograph, or hectograph processes.

Reproduction by any other process is

permitted.) Any style of type may be

used.

c. Contain an identification statement

on one of the first five pages of the

publication that includes the following

elements:

(1) Title.

(2) Issue date. The date may be

omitted if it is on the front cover or

cover page.

(3) Statement of frequency showing

how many issues are to be published

each year and at what regular intervals

(daily; weekly; monthly; monthly except

June; four times a year in June, August,

September, and December; annually;

etc.).

(4) Name and address of the nonprofit

organization, including street number,

street name, and ZIP+4 or 5-digit ZIP

Code. The street name and number are

optional if there is no letter carrier

service.

(5) Issue number. Every issue of each

publication is numbered consecutively

in a series that may not be broken by

assigning numbers to issues omitted.

The issue number may be printed on the

front or cover page instead of in the

identification statement.

(6) ISSN or USPS number, if

applicable.

(7) Subscription price, if applicable.

d. Consist of at least 25%

nonadvertising matter in each issue.

Advertising is defined in E211.11.0.

* * * * *

[Renumber current 5.8 and 5.9 as 5.12

and 5.11, respectively; add new section

5.10 as follows:]

5.10 Products Mailable at Special

Bulk Third-Class Rates

The following products are mailable

at special bulk third-class rates:

a. Low-cost items within the meaning

of 26 U.S.C. 513(h)(2), Internal Revenue

Code. At the beginning of each calendar

year, the value of low-cost items is

adjusted for cost of living. The standard

established on January 1, 1995,

provided that low-cost items have a cost

of not more than $6.56. The cost is the

cost to the qualified nonprofit

organization that mails the item or on

whose behalf the item is mailed.

b. Items donated or contributed to the

qualified organization. Such items do

not have to meet the definition of lowcost as described in 5.10a.

c. A periodical publication (as defined

in E211) of a nonprofit organization

unless it is ineligible under the

provisions of E370.5.0 to be mailed at

the special bulk third-class rates.

* * * * *

An appropriate amendment to 39 CFR

111.3 to reflect these changes will be

published if the proposal is adopted.

Stanley F. Mires,

Chief Counsel, Legislative.

[FR Doc. 95–5458 Filed 3–6–95; 8:45 am]

BILLING CODE 7710–12–P

ENVIRONMENTAL PROTECTION

AGENCY

40 CFR Parts 51 and 58

[AD–FRL–5157–7]

Proposed Requirements for

Implementation Plans and Ambient Air

Quality Surveillance for Sulfur Oxides

(Sulfur Dioxide) National Ambient Air

Quality Standards

AGENCY: Environmental Protection

Agency (EPA).

ACTION: Proposed rule.

SUMMARY: Today’s action proposes

implementation strategies for reducing

short-term high concentration sulfur

dioxide (SO2) emissions in the ambient

air. The EPA is concerned that a

segment of the asthmatic population

may be at increased health risk when

exposed to 5-minute peak

concentrations of SO2 in the ambient air

while exercising. ‘‘Exercising’’ in this

case can include walking up stairs or

hills, as well as more strenuous

activities.

In a related document published on

November 15, 1994 in the Federal

Register (part 50/53 document), EPA

proposed not to revise the current 24-

hour and annual primary national

ambient air quality standards (NAAQS)

for sulfur oxides (measured as SO2)

while soliciting comment on the

possible need to adopt additional

regulatory measures to address shortterm peak SO2 exposures. The three

alternatives under consideration

include: Augmenting the

implementation of the existing

standards by focusing on those sources

or source types likely to produce high

5-minute peak SO2 concentrations;

establishing a new regulatory program

under the authority of section 303 of the

Clean Air Act (Act) to supplement

protection provided by the existing SO2

NAAQS; and revising the existing SO2

NAAQS by adding a new 5-minute

NAAQS of 0.60 ppm SO2, 1 expected

exceedance. All three regulatory

alternatives would be implemented

through a risk-based targeted strategy

designed to protect the population at

risk while minimizing the burden on the

States for implementation.

This document presents EPA’s

proposed targeted implementation

strategy and the associated regulatory

requirements for implementing each of

the regulatory measures under

consideration. Also in this document,

EPA solicits comments on appropriate

changes to the new source review (NSR)

programs as they relate to the 5-minute

NAAQS regulatory alternative, and EPA
Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules 12493

proposes to incorporate appropriate

changes to the ambient air quality

surveillance requirements.

DATES: Written comments on this

proposal must be received by June 6,

1995. The EPA will hold a public

hearing on this document in

approximately 30 days and will

announce the time and place in a

subsequent Federal Register document.

ADDRESSES: Submit comments on the

proposed revisions to the requirements

for the preparation, adoption, and

submittal of implementation plans (two

copies are preferred) to: Office of Air

and Radiation Docket and Information

Center (Air Docket 6102), Room M 1500,

U.S. Environmental Protection Agency,

Attention: Docket No. A–94–55 (for part

51 comments) or A–94–56 (for part 58

comments), 401 M Street, S.W.,

Washington, DC 20460. The docket may

be inspected between 8:00 a.m. and 5:30

p.m. on weekdays, and a reasonable fee

may be charged for copying. The Air

Docket may be called at 202–260–7548.

FOR FURTHER INFORMATION CONTACT:

Laura D. McKelvey, Information

Transfer and Program Integration

Division (MD–12), U.S. Environmental

Protection Agency, Research Triangle

Park, NC 27711, telephone (919) 541–

5497, for the part 51 SIP. For parts 51

and 52 new source review programs,

contact Dan deRoeck, Information

Transfer and Program Integration

Division (MD–12), U.S. Environmental

Protection Agency, Research Triangle

Park, NC 27711, telephone (919) 541–

5593. For part 58 ambient air quality

surveillance, contact David Lutz,

Emissions Monitoring and Analysis

Division (MD–14), U.S. Environmental

Protection Agency, Research Triangle

Park, NC 27711, telephone (919) 541–

5476.

Table of Contents

I. Background

II. Targeted Implementation Strategy

A. Background

1. Modeling

2. Ambient Monitoring

B. Implementing the Targeting Strategy

1. Ranking of Source Categories

2. Other Considerations

3. States’ Targeted SO2 Monitoring Program

4. Addressing the Problem

C. Relocating Monitors

1. Resource Concerns

2. Siting Concerns

3. Trends Data Concerns

4. Barriers

5. Conclusion

D. Compliance and Enforcement Issues

1. Averaging Times for Emission Limits

2. Malfunction Policy

3. Conclusion

III. Requirements Associated with Retention

of Existing NAAQS

IV. Requirements Associated with Retention

of Existing NAAQS and Implementation

of a Section 303 Program

V. Requirements Associated with a New 5-

Minute SO2 NAAQS

A. Targeted Implementation Strategy

B. Designations—Section 107

1. Statutory Requirements

2. Timeframe for Submittal of Designations

by State

3. Determining Initial Designation of an

Area

4. Determining the Boundaries of

Designated Areas

5. Promulgation of Designations by EPA

6. Failing to Submit Designations

C. State Implementation Plans (SIP’s)

1. General SIP Requirements—Section

110(a)

2. General SIP Requirements—Section

110(a)(2)

a. Statutory and Existing Regulatory

Requirements

b. Statewide SIP’s for the Revised SO2

NAAQS

c. New Source Review Issues

d. Schedule for Submittal of Section

110(a)(1) SIP’s

D. Nonattainment Area Requirements

1. Attainment and SIP Submittal Dates

2. Classifications—Section 172(a)(1)

3. Nonattainment Plan Provisions—Section

172(c)

a. Statutory and Existing Regulatory

Requirements

b. Reasonably Available Control Measures

(Including Reasonably Available Control

Technology)

c. Emission Inventory

d. Control Strategy Demonstration

e. Reasonable Further Progress

f. Permits for New and Modified Major

Stationary Sources

g. Contingency Measures

E. SIP Processing Requirements

1. SIP Completeness

2. Approval/Disapproval of Plan

3. Sanctions and Other Consequences of

SIP Deficiencies

VI. Significant Harm Levels and Episode

Criteria

VII. Proposed Revisions to Part 58

Monitoring Regulations

A. Section 58.1 Definitions

B. Appendix C—Ambient Air Quality

Monitoring Methodology

C. Appendix D—Network Design for State

and Local Air Monitoring Stations

(SLAMS) and National Air Monitoring

Stations (NAMS)

D. Appendix F—Annual SLAMS Report

E. Appendix G—Air Quality Index

Reporting and Daily Reporting

VIII. Transition Issues

IX. Other Clean Air Act Amendment

Authorities Affecting SO2 Sources

X. Public Participation

A. Comments and the Public Docket

B. Public Hearing

XI. Administrative Requirements

A. Regulatory Impact Analysis

B. Impact on Reporting Requirements

C. Impact on Small Entities

D. Reduction of Governmental Burden

E. Environmental Justice

Appendix A—References

SUPPLEMENTARY INFORMATION:

I. Background

As required under sections 108 and

109 of the Act, EPA has completed a

thorough review of the air quality

criteria and the current SO2 NAAQS.

Based on the health effects information

assessed in the air quality criteria, EPA

provisionally concludes that the current

24-hour and annual primary standards

provide adequate protection against the

effects associated with those averaging

periods. As discussed in detail in the

part 50/53 document (59 FR 58958), the

key issue that emerged from the review

is whether additional regulatory

measures are needed to provide

additional protection for asthmatic

individuals that may be exposed to high

5-minute peak SO2 concentrations.

As discussed in the part 50/53

document, the available air quality and

exposure data indicate that the

likelihood that the asthmatic population

as a whole would be exposed to 5-

minute peak SO2 concentrations of

concern, while outdoors and at exercise,

is very low when viewed from a

national perspective. The data indicate,

however, that high peak SO2

concentrations can occur around certain

sources or source types with some

frequency, suggesting asthmatic

individuals that reside in the vicinity of

such sources or source types will be at

greater health risk than indicated for the

asthmatic population as a whole. These

assessments lead EPA to conclude that

if any additional regulatory measures

are adopted to provide additional

protection, they should be implemented

through a risk-based targeted strategy

that focuses on those individual sources

most likely to produce high 5-minute

peak SO2 concentrations.

Based on these consideration, EPA is

soliciting comment on the part 50/53

document on three regulatory

alternatives: (1) Augmenting

implementation of the existing

standards by focusing on those sources

or source types likely to produce high

5-minute peak SO2 concentrations; (2)

establishing a new regulatory program

under section 303 of the Act to

supplement the protection provided by

the existing NAAQS; and (3) revising

the existing NAAQS by adding a new 5-

minute standard of 0.60 ppm, 1

expected exceedance. Because the riskbased targeted strategy is an integral

part of each of the three alternatives

being proposed for comment, this notice

will first present EPA’s approach for

targeting sources with a high potential
12494 Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules

for causing or contributing to high 5-

minute peak SO2 concentrations. As

discussed below and in the part 58

notice, a key element of this strategy

will be to relocate existing SO2 monitors

to areas in proximity of point sources of

concern. The relocation of monitors is

necessary because the existing SO2

monitoring network is designed to

characterize urban ambient air quality

associated with 3-hour, 24-hour, and

annual SO2 concentrations. These

monitors are not located to measure

peak SO2 concentrations from point

sources. As a result, EPA’s existing

guidance on siting criteria, the spanning

of SO2 instruments, and instrument

response time likely leads to

underestimates of high 5-minute peak

SO2 concentrations. To address these

concerns, EPA is proposing revisions to

the ambient air quality surveillance

requirements (40 CFR part 58) and

proposed certain technical changes to

the requirements for Ambient Air

Monitoring Reference and Equivalent

Methods (40 CFR part 53) in the part 50/

53 document.

In addition to outlining the targeted

implementation strategy, this notice

presents EPA’s proposed program for

implementing the section 303 program

and the 5-minute SO2 NAAQS

alternative. Regardless of the alternative

selected (i.e., retain the existing

standards but augment their

implementation, establish a new 303

program, or add a new 5-minute

NAAQS), the targeted implementation

strategy would be used to identify areas

that may be subject to high 5-minute

SO2 concentrations. The measures that

sources must take if they cause or

contribute to such high peaks and the

actions that the States must take will

vary depending on the proposed

alternative, if any, selected.

The following discussion gives

statutory background information on the

regulatory approach used in addressing

air pollution. Under sections 108 and

109 of the Act, EPA is responsible for

issuing air quality criteria and for

proposing and promulgating NAAQS.

Under section 110(a)(1) and part D of

title I, the States then have primary

responsibility for implementing the

NAAQS. In broad outline, each State

must develop and submit to EPA a plan

that provides for attainment of each

NAAQS within certain time limits. The

EPA must review the SIP submittal and

approve or disapprove its provisions. If

States fail to submit required SIP’s or

submit inadequate SIP’s, and the

deficiencies are not cured within

specified time periods, the States

become subject to certain sanctions

under section 179, and EPA ultimately

becomes subject to an obligation to

promulgate a Federal implementation

plan (FIP). For a more complete

discussion of the provisions of title I of

the Act, see the General Preamble for

the Implementation of Title I of the

Clean Air Act Amendments of 1990

published in the Federal Register on

April 16, 1992 (57 FR 13498).

The 1990 Amendments preserved the

existing framework of the SIP process,

i.e., States are still responsible for

preparing and submitting SIP’s, and

EPA is still responsible for reviewing

and approving or disapproving SIP’s. In

addition, the 1990 Amendments, among

other things, provide EPA with the

unilateral authority to designate areas as

either attainment, nonattainment or

unclassifiable with respect to any

NAAQS (see generally, section

107(d)(1)). States with areas designated

nonattainment for a NAAQS are

required to submit SIP’s which provide

for attainment of that NAAQS. States

can face sanctions and other

repercussions if they fail to meet the

various SIP requirements of title I.

In general, for each of the proposed

regulatory alternatives, the Act may or

may not require specific actions on the

part of EPA or the States. If the existing

NAAQS is retained, then the Act

imposes no new SIP requirements on

EPA and the States, although EPA will

use its discretionary authority to

effectuate the Act’s protective purposes

by requiring States to implement

targeted monitoring around sources

capable of producing short-term high

concentrations of SO2 to the extent that

those sources contribute to ambient

concentrations of SO2. If the existing

NAAQS is retained along with a trigger

level for implementing an emergency

program under section 303, then the

State would be principally responsible

for developing and implementing the

necessary prevention and/or abatement

strategies. If a new 5-minute NAAQS is

established, States would have to

develop and submit SIP’s which provide

for implementation, maintenance and

enforcement of the new NAAQS.

Further discussion of the

requirements that are to be met by the

States is provided below with regard to

each of the additional regulatory

alternatives to be considered by EPA.

II. Targeted Implementation Strategy

This section principally proposes

EPA’s strategy to identify those areas

where the potential exists for

exceedances of the current SO2 NAAQS

as well as the potential for high 5-

minute concentrations of SO2. This

strategy has two stages. The first stage

is to identify potential problem areas

and then to conduct ambient monitoring

at those areas. The second stage is to

take corrective action should monitoring

conducted during the first stage reveal

concentrations in excess of the

appropriate SO2 NAAQS or trigger level.

To begin this strategy, EPA intends to

refocus Agency monitoring resources

into those areas with potential 5-minute

SO2 peaks. The development and

implementation of this strategy relies on

the ability of the States to identify the

specific emission and operating

characteristics of sources which can

contribute to violations of the existing

NAAQS as well as contribute to high 5-

minute SO2 concentrations. Successful

implementation of this strategy will

result in either the identification of

additional SO2 problem areas or the

conclusion that the ambient SO2

problem is largely solved. It also allows

EPA to apply finite resources in an

efficient way where public health is

most likely to be jeopardized by air

pollution. The EPA intends to pursue

this targeted strategy regardless of the

outcome of the NAAQS proposal

published in the part 50/53 notice and

solicits comments on the targeted

implementation strategy.

A. Background

1. Modeling

For implementing the current SO2

program, EPA has historically relied on

mathematical dispersion models for

predicting air pollutant concentrations

for the following needs: (1) For

redesignating areas to nonattainment or

attainment under section 107 of the Act;

(2) for setting emission limits for an

attainment strategy as required per 14

section 110(a)(2)(K) and part 40 of the

Code of Federal Regulations, § 51.115

(40 CFR 51.115); (3) for predicting

locations of maximum concentrations

for siting monitors; (4) for determining

boundaries of nonattainment areas; (5)

for predicting consumption of ambient

air increments under prevention of

significant deterioration (PSD); and (6)

for determining, under nonattainment

NSR, if the significance level, used for

determining if a major source or

modification is considered to cause or

contribute to a violation of the NAAQS,

is exceeded.

The ‘‘Guideline on Air Quality

Models (Revised),’’ EPA–450/2–78–

027R, hereinafter referred to as ‘‘the

Modeling Guideline,’’ has provided a

common basis for conducting such

modeling. The Modeling Guideline was

incorporated into 40 CFR part 51 on July

20, 1993 (58 FR 38816) as appendix W.

However, modeling is not currently

feasible for predicting 5-minute ambient
Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules 12495

air concentrations of SO2. This is due to

present uncertainties regarding the

ability of models to reliably predict SO2

concentrations for 5-minute periods and

uncertainties with the accuracy of the

input data needed to run the models. A

brief summary of issues follows.

Validation. Although models are

available, they have not been applied in

predicting 5-minute SO2 concentrations.

Model validation studies have not been

conducted to determine whether

existing models can estimate with

sufficient accuracy to be used in a

regulatory context. Model validation

studies are therefore necessary to

determine the precision needed for

input data for achieving the desired

prediction accuracy. This would help

determine, for example, whether on-site

5-minute meteorological data are

needed or if nearby National Weather

Service data are sufficient.

Emissions Data. In addition to the

unassessed uncertainties of models, the

accuracy and availability of input data,

such as emissions, meteorology, and the

occurrence of a short-term release (e.g.,

a process upset or control equipment

malfunction) necessary to run the

models, limits the ability to accurately

predict 5-minute SO2 concentrations at

this time. Obtaining accurate source

emission data for 5-minute periods is of

critical importance. However, it is

difficult to obtain such data since such

data often depend on trying to measure

emissions that may occur infrequently

and at unpredictable times,

concentrations, and flow rates

(estimates of both flow rates and

pollutant concentrations are necessary

to determine mass emissions unless a

mass balance can be performed, which

would be difficult on a 5-minute basis).

Moreover, emergency bypass valves,

where measurements of emissions might

be most appropriate under some

circumstances, are infrequently used

and therefore are not appropriate sites

for the installation of monitors for

continuous measurement of flow rates

or pollutant concentrations.

Predicting Short-term Events. Current

models used for predicting ambient air

concentrations rely on a known

emission release, usually some steadystate emission rate, and known past

meteorological data. Short-term models

use hourly weather data from the

National Weather Service or from onsite meteorological stations, which are

preprocessed before being used in the

model. Long-term models use joint

frequency distribution summaries of

wind speed, direction and atmospheric

stability category. In order to model for

emission releases due to malfunctions, a

method of determining the expected

frequency of these malfunctions would

have to be employed (e.g., a Monte Carlo

simulation which is a computer

simulation using random sampling

techniques to obtain approximate

solutions to mathematical or physical

problems especially in terms of a range

of values each of which has a calculated

probability of being the solution). To

date, EPA has never attempted to

integrate dispersion modeling with

malfunction frequency data to set

emission limits, or to perform any other

regulatory modeling tasks. Indeed,

EPA’s longstanding position has been to

regard malfunctions as violations of

applicable control requirements, subject

to enforcement, unless it can be shown

that such malfunctions are truly

unavoidable (Bennett, 1982). To allow

deviations from this policy, EPA would

need to develop a method along with

policy and guidance for its use, which

EPA does not intend to do at this time.

Meteorological Data. On-site

meteorological data are preferable, but

National Weather Service data may be

acceptable if a station is nearby and

deemed representative of the area

modeled. The meteorological data

requirements for 5-minute SO2

modeling could be determined through

model evaluation studies, as discussed

earlier in this section.

For these reasons, in contrast with

longer averaging periods, models cannot

currently be used to predict 5-minute

SO2 excursions needed to support a 5-

minute NAAQS. However, despite these

limitations, current models may still be

used as a tool in a qualitative sense in

the decision-making process for

determining boundaries of

nonattainment areas and for siting of

monitors in areas of maximum

concentrations. Consequently, the

targeted implementation strategy which

is designed to find areas exposed to

high, 5-minute concentrations of SO2

will rely principally on ambient air

monitoring instead of modeling.

2. Ambient Monitoring

Requirements for monitoring are

established at 40 CFR Part 58—Ambient

Air Quality Surveillance. This part: (1)

Contains criteria and requirements for

ambient air quality monitoring and

requirements for reporting ambient air

quality data and information; (2)

contains requirements pertaining to

provisions for an air quality surveillance

system in the SIP; (3) acts to establish

a national ambient air quality

monitoring network for the purpose of

providing timely air quality data upon

which to base national assessments and

policy decisions; and (4) includes

requirements for the daily reporting of

an index of ambient air quality to ensure

that the population of major urban areas

are informed daily of local air quality

conditions.

In the early 1970’s when EPA and the

States first began to monitor for SO2 in

the ambient air, SO2 emissions were

greater and more widespread than

today. Combustion of sulfur-bearing

fuels occurred not only in industrial and

utility settings but in private settings as

well. Fuel oil and coal were burned in

residences and building boilers for

warmth. For this reason and because of

the potential for exposures of the

population, large metropolitan areas

were generally selected for monitoring.

Sulfur oxide emissions have decreased

about 27 percent since 1970 (EPA,

1992b). Today most residences and

buildings use electricity or natural gas

for heating and nearby industrial or

utility sources have installed control

devices or have switched to lower sulfur

fuel resulting in less sulfur emissions in

the vicinity of the ambient air monitors.

Because of these reductions in SO2

emissions in populated areas, only a

small number of monitors are now

recording exceedances. Even these few

exceedances are due not to area sources

of SO2 but instead to emissions from

nearby industrial sources. Despite these

changes in the profile of sources of SO2

emissions, the SO2 ambient air

monitoring network has not been

modified to reflect the ambient air

quality for SO2 near industrial sources.

As a result of past emphasis on urban

scale air quality management, SO2

monitoring networks are designed to

measure population exposure over a

large area and are not generally

designed to measure the influence of

specific point sources. To an increasing

extent, therefore, SO2 nonattainment

areas have been identified by air quality

dispersion models and defined by one

or a few point sources with probability

of causing a violation of the SO2

NAAQS when operating at allowable

emission limits at times of unfavorable

meteorology. Increased concerns about

high short-term concentrations of SO2

occurring near point sources, together

with the prevalence of low

concentrations at existing networks and

the inability of models to predict shortterm concentrations, suggest a need to

redirect monitor networks near these

sources.

As already briefly discussed, there are

about 675 SO2 SLAMS monitors across

the Nation. In this notice, EPA is

proposing changes to 40 CFR part 58 to

allow for fewer SLAMS monitors per

metropolitan statistical area. This will

enable monitors and resources to be

redirected towards placing monitors
12496 Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules

near point sources. There is a higher

initial cost associated with finding and

setting up new monitoring sites than the

annual operating cost of the monitor

itself. Because of this and because of

limited State monitoring resources, not

all monitors initially freed up can be

immediately placed around a targeted

source, but will be phased in over a

period of time.

For the reasons stated above, EPA

proposes to direct States to redeploy

SO2 monitors around targeted sources of

SO2 and respan the instrumentation at

selected sites to measure values above

0.5 parts per million (ppm). The

monitors will be sited at microscale,

middle, or neighborhood distance from

the targeted sources in order to best

measure high, 5-minute concentrations

of SO2. Micro, middle, neighborhood,

and urban scales are all more

completely defined in 40 CFR part 58,

appendix D. The EPA and States will

first monitor around those sources in

areas with population with the greatest

potential to exposure to 5-minute, peak

SO2 levels. The EPA and States will

consider discontinuing the operation of

existing monitors and relocate them for

the purpose of monitoring around

targeted sources (see part 58 discussion

published elsewhere in this notice for

monitoring requirements).

B. Implementing the Targeting Strategy

As discussed earlier, the available air

quality and exposure information

indicates that a large degree of

protection against exposure to shortterm peak SO2 concentrations is

provided by the current NAAQS. Full

implementation of the Acid Rain

Program will result in further reduction

of SO2 emissions and the likelihood of

peak SO2 concentrations. The available

data indicate, however, that peak

concentrations of SO2 can still occur

around certain sources or source types

with some frequency, suggesting

asthmatic individuals who reside in the

vicinity of such sources or source types

will be at greater health risk than

indicated for the asthmatic population

as a whole. These assessments have led

EPA to conclude that any regulatory

measures adopted to provide additional

protection should be implemented

through a risk-based targeted strategy

that focuses on those individual sources

more likely to produce high 5-minute

peaks.

Therefore, in order to gather more

information, to focus implementation

efforts on those sources that EPA’s

existing data suggest may pose the

greatest health risk, and to allocate

monitoring resources as efficiently as

possible, EPA has developed an

approach to guide States in developing

a prioritized list of sources to be

targeted for monitoring. As further

discussed below, potential sources have

been placed in one of three groups

based on the overall likelihood of the

source category to emit high 5-minute

SO2 peaks. However, before redeploying

monitors, States must evaluate each of

these facilities individually, basing their

decision on more specific information

such as size, configuration, compliance

history and proximity to population

centers.

As just described, States need to

review their current SO2 monitoring

networks to determine which monitor

sites should continue operating and

which should be discontinued and

relocated around potential sources. The

EPA will work with each State to

develop a targeted SO2 monitoring plan

to implement the strategy, based on the

number of targeted sources, SO2

monitoring resources, and within a

reasonable time horizon.

The EPA believes that new locations

for siting monitors should be in the

vicinity of sources suspected of causing

short-term SO2 peaks. Some examples of

sources which emit SO2 are petroleum

refineries, sulfuric acid plants, fossil

fuel-fired industrial boilers, utility

boilers, pulp and paper mills, iron and

steel mills, wet corn milling operations,

nonferrous smelters, carbon black

manufacturing, portland cement

manufacturing, phosphatic fertilizer

production, and natural gas production.

This list is not exhaustive and could

potentially include other process

sources with known emissions of SO2.

These sources have the ability to emit

relatively large quantities of SO2 over

short durations. Such large quantities of

emissions may be due to releases from

batch type operations, operational

malfunctions or upsets requiring control

equipment bypasses, control equipment

malfunctions that can result in

uncontrolled emissions to the

atmosphere, startup/shutdown, short

stacks subject to downwash, or fugitive

emissions.

1. Ranking of Source Categories

The information most heavily relied

on in developing this ranking of source

categories was: (1) Available 5-minute

air quality data documenting the

number of high, short-term

concentrations observed in the vicinity

of various sources by monitoring

networks (Table 3–1, EPA, 1994b); (2)

estimates of exposures from various

source types, which integrated a

source’s likelihood to emit short-term

SO2 peaks with the size and activity of

the surrounding population, as

summarized in Table 3–5, Table B–1,

and Table B–2 (EPA, 1994b), as well as

accompanying documentation

(Rosenbaum et al., 1992; Stoeckenius et

al., 1990; Burton et al., 1987); and (3)

the Geographic Targeting Data Base for

nonutility sources that is derived from

combining a census of manufacturing,

the EPA Facilities Index System, and

the EPA Aerometric Information

Retrieval System (AIRS) into a projected

source impact data set. This data base,

which will be available through AIRS, is

a data set of nonutility sources sorted on

the projected annual process emissions

per source and per size category.

In order to further refine the ranking

of source categories, both within and

between groups, EPA solicits technical

information concerning several issues

which include: (1) The likelihood of

source categories to produce short-term

SO2 peaks; (2) the characteristics, within

a source category which cause a subset

of facilities to be more likely to produce

short-term SO2 peaks; and (3) the factors

which are likely to drive the variability

in SO2 emissions of individual facilities

within a source category.

The ranking described here separates

source categories into three groups: A,

B, and C. In pursuit of this targeting

strategy, EPA intends to require States

to evaluate groups A, B, and C sources

and produce a refined monitoring plan.

States are free to substitute, e.g., group

B sources for group A sources in their

priority schemes, but should provide a

reasoned justification for finding that

the risks posed by these sources justifies

such substitution. Ultimately, EPA

anticipates that sources in all three

groups will be assessed for their

exposure potential and appropriate

actions taken to address them. The EPA

believes that there is a higher

probability of finding individual sources

that produce high, short-term ambient

concentrations of SO2 within each

source category in group A than in the

other groups. As such, they are judged

in general to pose the highest risk of

exposing population in their vicinity to

high, short-term concentrations of SO2,

as well as potentially exposing some

individuals to several peaks per year.

The source categories within group A

were generally found to meet two of the

three following characteristics. Either

the source category contained SO2

sources which: (1) Have a high emission

rate, (2) are near monitors which

measured 5-minute peaks, or (3) are

estimated, based on exposure analysis,

to expose a high number of asthmatics

living in their vicinity at elevated

ventilation rates to SO2 concentrations

greater than 0.6 ppm. In addition, these

source categories are known to have
Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules 12497

short-term releases due to events

discussed later.

Group A consists of the following

source categories: Sulfite pulp and

paper mills, primary copper smelters,

primary lead smelters, aluminum

smelters, and the top 20 percent of the

petroleum refineries in terms of

projected annual emissions of SO2 as

listed in the Geographic Targeting Data

Base.

Source categories were selected for

group B because they have high annual

emissions or are subject to events

leading to short-term releases of SO2. In

addition, in some instances, there were

air quality or exposure data which

indicate the source category to be of

concern for emitting short-term SO2

peaks.

The EPA judged group B source

categories to have the potential to

produce high 5-minute peaks of SO2 but

to pose less risk than group A because:

(1) Air quality or exposure data

indicated that the potential to emit high

5-minute peaks of SO2 was less than for

group A; (2) the grouping was based on

annual emission data, but lacked 5-

minute data to estimate risk; or (3) the

overall risk posed by the source category

was judged to be low. This was the case

for industrial boilers because, while

exposure analysis indicated that this

group was responsible for a

considerable number of exposures, the

exposures were attributed to a very

small subset of industrial boilers. The

EPA expects that States will examine

their source categories within this group

very closely for inclusion in the targeted

SO2 monitoring plan.

The group B sources are as follows:

Kraft sulfate pulp and paper mills,

secondary copper smelters, secondary

lead smelters, the remaining petroleum

refineries, iron and steel mills, carbon

black manufacturing, portland cement

manufacturing, crude petroleum and

natural gas extraction processes,

phosphatic fertilizer manufacturing,

industrial boilers, and sulfuric acid

plants.

Industrial boilers were placed in this

group because they accounted for about

30 to 50 percent of the 5-minute SO2

exposure events given in the staff paper

supplement (Table 3–5, EPA, 1994b).

However, in a study by Stoeckenius et

al. (Table 2–14, 1990), approximately

half of the total industrial boiler

exposures were attributed to a very

small proportion (≤2 percent) of the

total population of industrial boilers

analyzed. Good engineering judgment

suggests that the use of higher sulfur

coal and short stack height would

contribute to an increased likelihood of

producing ambient SO2 peaks.

The group C source category consists

of utility boilers. Although utility

boilers can emit large quantities of SO2,

many power plants are not anticipated

to cause 5-minute violations despite

their high emission rates due to tall

stacks and steady-state operating

conditions. They are placed in group C

because as a source category, utility

boilers may be responsible for

approximately 17 to 37 percent of total

estimated exposures (Table 3–5, EPA,

1994b). However, the risk of exposures

is very unevenly distributed across the

sources in this category. Approximately

75 percent of the utility sector’s posttitle IV exposures were estimated to

result from less than 10 percent of the

power plants (Rosenbaum, 1992, Table

3, Burton et al., 1987).

With the passage of the 1990

Amendments, Congress created under

title IV an SO2 emission trading program

as an integral part of the Acid Rain

Program, which is designed to reduce

SO2 emissions by 10 million tons

nationwide by the year 2010. Phase I,

which begins in 1995, reduces

emissions from the 110 largest emitting

power plants, which are identified in

table A of section 404 of the Act. The

Acid Rain Program introduces a

flexibility for sources to choose the most

cost-effective compliance strategy to

achieve their emission reduction

obligations and to maintain the national

cap of 8.95 million tons of SO2

emissions. Compliance flexibility may

involve switching to low-sulfur coal,

scrubbing, conservation, other emission

control technologies, or buying SO2

allowances.

Title IV sources participating in the

Acid Rain Program are under the

obligation to match their annual SO2

emissions with their allowance

holdings. They are also required to meet

all other requirements of the Act and

regulations that apply to them,

including the NAAQS. Therefore, the

compliance flexibility offered under the

Acid Rain Program does not permit any

source to violate regulations adopted to

attain or maintain the SO2 NAAQS.

Emissions from these sources will be

closely tracked, because title IV sources

are also required to install continuous

emissions monitoring systems (CEMS)

and report to EPA on a quarterly basis

their emissions of SO2, nitrogen oxides,

and carbon dioxide.

Further improvements in air quality

are expected to be realized from the SO2

emission reductions under Phase II of

the Acid Rain Program to be

implemented by January 1, 2000 under

title IV of the Act. Because of the

potential to have higher emissions and

because of potential plume downwash

and interaction of complex terrain, EPA

is mainly concerned with those power

plants that buy allowances rather than

reduce emissions themselves in order to

comply with title IV and those located

in complex terrain, respectively.

Complex terrain is defined for modeling

applications as that terrain exceeding

the height of the stack, but this

definition is being applied here for

monitoring applications as well. In a

study done for EPA, that is contained in

the docket for this rulemaking

(Polkowsky, 1991), many of the

predicted exceedances of the SO2

standards in the vicinity of power plants

should be reduced or eliminated by

allocating allowances based on a

reduced rate under Phase II. Any

remaining exceedances not addressed

by the more restrictive Phase II emission

rates will require a reanalysis of the SO2

NAAQS control strategy demonstration

and consideration of more restrictive

emission limits to protect the air quality

standards.

Because of the SO2 reductions that

will occur under the Acid Rain Program,

the accurate stack monitoring of their

emissions, and the long-range

atmospheric transport of these

emissions due to taller stacks at most

large utilities, EPA believes that higher

priority in placing ambient monitors

should be given to nonutility sources.

However, in instances at a particular

power plant where the possibility of

high 5-minute emission peaks still

exists, EPA believes that consideration

should be given by the State to locating

monitors near the facility.

2. Other Considerations

In addition to the guidelines and

groupings listed above, which are based

largely on available information

concerning the likelihood of a source

type to produce concentrated peaks of

SO2, States may have other information

which may lead them to believe that a

source located in a lower probability

group should be made a higher priority

for SO2 monitoring. Of particular

importance to consider is any available

information on potential population

exposure, inferred in part by the

population in the vicinity of the source.

In addition, other information can be

incorporated by States into an

evaluation of the relative likelihood of

sources under their jurisdiction to

produce SO2 exposures, thus refining

their judgments on priority of

monitoring decisions. Such other

information can include the type of

process being used (i.e., one type of

process within a source category may be

less efficient and known to emit more

SO2 than a newer one), a history of past
12498 Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules

upsets or malfunctions, the type of fuel

used, the type of terrain around the

source (e.g., is the source in a river

valley or on flat terrain), knowledge of

how well the source is controlled, and

a history of citizen complaints, and

should be considered by the States

when deciding which sources to

monitor first. Such considerations

would be noted in each State’s targeted

SO2 monitoring plan presented during

the annual SLAMS review as described

below.

As part of the targeting strategy, the

States will also need to decide how

much relative weight should be given

any particular source. For example, a

State would have to determine how

heavily to weigh a group A source in a

less densely populated area versus a

group C source burning a high sulfur

fuel in a more densely populated area.

In addition, some sources are often

found collocated with other sources

such as sulfuric acid plants with copper

smelters. Industrial boilers may be

located with any number of process

sources. There may be small geographic

areas where there is clustering of an

assorted number of SO2 sources. In

these situations there is no precise way

to determine what source should be

targeted first at this point. For this

reason, the decision making should rest

with the States who have better

knowledge of the individual

circumstances pertaining to the

potential sources to be targeted.

3. States’ Targeted SO2 Monitoring

Program

The EPA will review and take

appropriate action on the States’

targeted SO2 monitoring plans during

the annual SLAMS network review

process to ensure that States provide an

adequate rationale for any deviations

from the grouped approach. The States

are then expected to present to EPA in

a targeted SO2 monitoring plan at the

annual SLAMS network review their

listing of sources to be monitored, the

schedule for conducting such

monitoring, and the rationale for

selecting these sources. Requirements

for the targeted SO2 monitoring plan are

discussed later in this notice for part 58

but EPA expects the targeted SO2

monitoring plan to be a dynamic

process that could change depending on

data gathered from early rounds of

monitoring or changes at targeted

sources, such as installation of control

equipment.

Section 110(a)(2)(B) of the Act

requires SIP’s which provide for the

establishment and operation of

appropriate devices, methods, systems,

and procedures necessary to monitor,

compile and analyze data on ambient air

quality. Should EPA determine that a

State’s targeted SO2 monitoring plan is

inadequate, then EPA expects to issue a

call for a SIP revision under section

110(k)(5) of the Act based on a finding

that the SIP is substantially inadequate

in meeting the requirement of section

110(a)(2)(B). The EPA solicits comments

on all aspects of this approach to

grouping of sources to investigate

potential air quality problems.

In the State targeted SO2 monitoring

plan, EPA expects SO2 monitoring

network reviews to be completed within

1 year of the effective date of

promulgation of any of the three

regulatory alternatives. Implementation

of network revisions is expected to take

longer.

4. Addressing the Problem

Regardless of the regulatory

alternative chosen by the Administrator,

those areas which have monitored

exceedances of the existing or revised

NAAQS or of a section 303 trigger level

should undergo a compliance

inspection by the State of the targeted

source. If the source is out of

compliance, EPA expects that the

responsible air pollution control agency

will initiate appropriate enforcement

action to bring it into compliance, e.g.,

by using available administrative or

judicial enforcement authorities. If the

source is in compliance, the State will

need to pursue other appropriate

solutions to the problem as discussed

later in section III.

The EPA encourages States to pursue,

where appropriate, the enforcement and

improved compliance options before

other regulatory actions. In many cases,

air quality problems may be due to poor

operation and maintenance or other

resolvable compliance problems. In

these instances, enforcement action can

result in timely resolution of violations

and avoid the sometimes lengthy

regulation development process.

However, the State should pursue

existing regulatory options where the

regulations are inadequate, e.g., because

the source is in compliance with the

existing regulations and an air quality

problem still exists.

C. Relocating Monitors

The EPA’s criteria for the network

design of monitors are discussed in 40

CFR part 58, appendix D. Elsewhere in

this notice, EPA is proposing changes to

part 58 in order to implement the

proposed targeting program. The EPA

recognizes that it is not a trivial matter

to relocate monitors and that there are

concerns that agencies will need to

consider in making relocation decisions.

1. Resource Concerns

The EPA believes that the resources

currently devoted to monitoring

ambient concentrations of SO2 may be

more effectively utilized through

systematic evaluations and

reconfigurations of existing monitoring

networks. However, even if States and

locals acquire no additional SO2

monitors and rely solely on the current

number of monitors, there will be some

costs incurred when relocating

monitors. Costs associated with moving

a monitor include the resources taken in

locating new sites and negotiating leases

along with the capital costs of a new

shelter and associated equipment.

Because of the costs for relocating

monitors, not all monitors freed up can

be immediately placed around a

targeted source, but will be phased in

over a period of time. The operating

costs saved by not operating these

monitors will be used toward the costs

of relocating monitors.

In more detail, the costs for moving an

SO2 monitor have been calculated in

1994 dollars to be $60,940 per site.

These costs include initial capital costs,

operation, and amortization. The initial

costs include network design and site

selection, land lease, power drop,

shelter, site preparation, calibration

equipment, data logger, quality

assurance plan preparation, etc. The

operation costs include routine site

visits, repairs, maintenance, data

acquisition and reporting, quality

assurance calibrations, and supervision.

The amortization costs for replacement

capital equipment were also calculated.

The total costs for the initial 3 years

are summarized as follows. The existing

network of 679 NAMS, SLAMS, and

industrial monitors costs about $16

million per year. The first year costs for

reconfiguration and operation of NAMS,

SLAMS, and industrial monitors in

order to comply with changes to 40 CFR

part 58, which is being proposed in this

notice and is not a result of the targeted

implementation strategy, is estimated to

be $12.4 million per year. This will

leave an available $3.6 million to be

used toward the targeted

implementation strategy the first year to

establish and operate four monitors

around 15 sources.

The second year costs for operating

the NAMS, SLAMS, industrial, and

targeted implementation strategy

monitors is estimated to be $9.6 million

dollars, making available $6.4 million

for the targeted implementation strategy.

This will allow for establishing sites

around 26 sources in addition to the 15

sources from the first year for a total of

41 targeted sources.
Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules 12499

The third year costs for operating

monitors are estimated to be $11.4

million, leaving $4.6 million for the

targeted implementation strategy. This

will allow for establishing sites around

16 sources in addition to the 41 sources

established in the first and second years

for a total of 57 targeted sources. The

EPA estimates that monitors at 7 of the

15 sources established in the first year

would be moved in the third year due

to no monitored violations.

2. Siting Concerns

The EPA is aware of the many

considerations that arise when siting

monitoring stations. Monitors are

usually sited where electrical power is

already available, they are reasonably

secure, the immediate environment

satisfies the siting criteria of part 58,

and they are in proximity to the desired

locations. Waiver provisions are also

included in the regulations to deviate

from siting criteria when appropriate.

Generally, monitors are sited at or

within reasonable proximity of the

desired locations. For purposes of

convenience, monitors are sometimes

sited where other pollutants are already

monitored.

When conducting the SO2 network

review, EPA-approved air quality

models and saturation studies may be

used to predict locations where

maximum concentrations are expected

within the vicinity of SO2 sources or

clusters of sources. As discussed earlier,

models can be used in a qualitative

sense to predict relative ambient

impacts and are useful as a tool for

establishing preferred monitor locations

for predicting 5-minute concentrations.

3. Trends Data Concerns

A potential concern regarding the

movement of monitors is the effect on

EPA’s ability to detect and evaluate

trends in air quality. When monitors are

operated in the same locations for

several years, it is possible to account

for the effects of meteorology, seasonal

patterns in air pollutant concentrations

and other variables specific to a monitor

location. When monitors are moved, the

confidence in detecting trends in air

pollutant concentrations is

compromised due to a new set of

variables that may affect ambient

concentrations at the new location.

The EPA needs to maintain a certain

number of monitors for detecting and

evaluating trends in air pollutant

concentrations. However, EPA believes

that a sufficient number of monitors

now used for trends analyses are not

critical to the objectives of trends

reporting and should be considered for

relocation. Elsewhere in this notice, the

EPA is proposing changes to 40 CFR

part 58, appendix D, in which a

minimum number of SO2 monitors in

the metropolitan areas will be retained

for trends purposes.

4. Barriers

Certain institutional barriers may be

encountered in some attempts to

relocate monitors. These stem from the

separate political entities responsible for

implementation of air pollution control

programs at the State and local levels

throughout the U.S. Where monitor sites

considered for relocation are within the

boundaries of one political entity, the

problems are diminished, since the

resources necessary to maintain existing

monitoring sites may be redirected to

the new sites, providing the SO2

monitor is not sharing a site with other

pollutant monitors. Sites in a network

around targeted sources of SO2

emissions which are located in different

States or air pollution control districts

may present some added difficulties. In

such cases, resources, such as grants for

support of air pollution planning and

control programs as allowed under

section 105 of the Act, may be

redirected by EPA to aid in relocating

and maintaining new monitoring

stations.

5. Conclusion

In general, EPA believes that a portion

of the monitors now directed to

monitoring ambient air quality in

population areas for trends purposes

should be considered for relocation.

While EPA may not normally require

monitors operated by industries to be

relocated and thus industry-operated

monitors will not be candidates for

relocation, EPA strongly encourages

companies to evaluate their networks in

light of today’s notice. However,

quality-assured data from such monitors

could allow for the relocation of nearby

SLAMS monitors to other locations if

monitored air quality concentrations

from industry-operated monitors

provide assurances that the SO2 NAAQS

are maintained.

D. Compliance and Enforcement Issues

Certain compliance and enforcement

issues will arise only if either the

section 303 alternative or the new 5-

minute NAAQS alternative is selected.

The issues are how to determine

compliance to ensure protection of a

trigger level or NAAQS that has a 5-

minute averaging period, and what

actions are appropriate by the State

when the cause of the violation may be

process upsets, startup or shutdown,

batch operations, or other nonsteadystate sources. As is currently done with

the NAAQS, measurement of SO2

ambient air concentrations with ambient

air monitors under each of the three

proposed regulatory alternatives will

serve as indicators of compliance.

Enforcement will be based on the results

of compliance inspections at the source,

and the compliance inspection will be

based on requirements in the applicable

operating permit or SIP. In most

instances, EPA believes that in order to

ensure protection of the 5-minute

NAAQS or trigger level, compliance will

need to be determined through sources

meeting recordkeeping and reporting

requirements or carrying out any other

agreed-upon actions designed to reduce

short-term emission peaks.

1. Averaging Times for Emission Limits

Under EPA’s policy for emissions

averaging under the current SO2

NAAQS, sources are to be controlled

through the imposition of emission

limits having averaging times consistent

with the averaging period of the air

quality standard of concern. As an

example, in order to protect the SO2

ambient air quality standard that has

been established for a 24-hour period,

mass emission limits for sources should

normally allow averaging of emissions

over no more than a 24-hour period

when determining compliance with the

limits. The purpose of this is to restrict

extreme variations in emissions of short

duration that might otherwise be

allowed to occur if emission variations

are averaged over much longer periods

(e.g., 30 days). Air quality

concentrations in excess of the standard

could be produced while sources are

still complying with long-term average

emission limits by reducing emissions

sufficiently at other times within their

emission averaging periods.

A variety of emission limit averaging

times had been developed by State and

local agencies for SIP’s both prior and

subsequent to the implementation of

this policy on averaging. As a result,

those SIP’s with averaging times

inconsistent with the policy that were

adopted prior to implementation of the

policy are included in an effort by EPA

to correct general SIP enforcement

deficiencies. The EPA has not taken

final action on those rules developed

subsequent to the policy.

The EPA has allowed the use of stack

tests and analysis of fuel samples for

sulfur content as surrogates for

continuous compliance monitoring with

the emission limits. In many cases,

these methods will continue to be

feasible for ensuring compliance with a

5-minute trigger level or NAAQS.

Technically, SO2 emissions can be

measured in a stack at intervals less
12500 Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules

than 5 minutes using Method 6c (the

instrumental analyzer procedure) in

Appendix A of 40 CFR part 60 or by

using a CEM. However, EPA believes

that in many instances 5-minute

releases of SO2 that would cause

exceedances of a 5-minute NAAQS or

trigger level will occur at unpredictable

times or as fugitive emissions (i.e., not

through a stack), making stack tests an

impractical compliance method. Nor

may sampling fuel at 5-minute intervals

be a practicable alternative as in the

case of coal in which sulfur content may

not be homogeneous. In addition, the

source of the emission may not be due

to combustion of fossil fuel but to

chemical process emissions.

The EPA believes that in most

instances, in order to attain a 5-minute

NAAQS or trigger level, the State will

not be able to rely on measurable

emission limits but instead on actions

by the source to, for example, modify

equipment or process or to have

improved maintenance that will address

the emission releases that are causing 5-

minute exceedances. Because of these

potential limitations to determining

compliance of emission limits designed

to protect a 5-minute NAAQS or trigger

level, compliance will in most instances

need to consist of the State ensuring that

the source has implemented the

necessary remedies. Verification that

actions have been effective will require

that ambient air monitoring continue for

a reasonable period, e.g., another 2 years

following the corrective action.

However, in those instances where

emissions can be feasibly measured on

a 5-minute basis or it is determined that

fuel sampling is a feasible compliance

indicator, the State may elect to set an

emission limit and use emission

measurement or fuel sampling as the

method for determining compliance.

2. Malfunction Policy

As stated previously, EPA has on

occasions used its enforcement

discretion in determining how and

whether to act on unavoidable

violations of source emission limits

during periods of startup, shutdown and

malfunction (40 CFR 60.11(d)). This

policy recognizes that during startup

and shutdown conditions, effective

pollutant control may sometimes not be

technically feasible due to process

temperatures and pressures that have

not yet stabilized. The policy also

recognizes that certain source

malfunctions are not reasonably

foreseeable and are unavoidable, which

result in uncontrolled emissions to the

atmosphere. Clearly, in many cases,

forces of nature such as floods,

tornadoes and lightning strikes can

overwhelm a source’s ability to function

in a normal fashion and may produce

conditions that preclude proper

operation of sources or control

equipment. However, some conditions

may be reasonably anticipated and

proper design of equipment can

ameliorate their effects (e.g., grounding

of equipment for lightning protection,

observation of flood plains, etc). It is

possible in some cases to address this

through design of redundant control

systems to guard against the release of

uncontrolled emissions to the

atmosphere should one system suffer a

malfunction; however, the cost may be

prohibitive and such systems are not

uniformly required. Some SO2 control

systems offer this protection, such as

dual acid plants operated in parallel at

petroleum refineries. Should one plant

experience operational problems in

such cases, the other is available to

provide a continued partial level of

sulfur (and ultimately SO2) removal.

3. Conclusion

As is currently done, where there

have been monitored violations of the

24-hour, 3-hour, or 5-minute SO2

NAAQS or trigger level, the State shall

be required to determine the source of

the SO2 emissions and investigate the

cause of the emissions at that source.

Where the results of these investigations

demonstrate that improper operation

and maintenance practices and/or poor

control equipment design are primarily

responsible for release of uncontrolled

emissions to the atmosphere, the State

shall be expected to work with the

source to take appropriate actions to

reduce inadequately controlled source

emissions.

For purposes of verifying the results

of any corrective actions taken and

compliance, the EPA intends to rely on

continued ambient air monitoring. The

EPA also anticipates the need to review

the implementation of its malfunctions

policy in light of the concerns discussed

in this document with the possible

result of more stringent showings

required to justify the conclusion that

malfunctions are truly unavoidable.

Recordkeeping based on earlier baseline

assessments of the problem at the source

should be maintained at the source to

assist in evaluations should further

exceedances be monitored.

III. Requirements Associated With

Retention of Existing NAAQS

The State is not required to revise its

SIP to address 5-minute, high

concentrations of SO2 if the existing

NAAQS is retained. However, in concert

with changes in monitoring

requirements for part 58 proposed in

this document, as discussed above, EPA

is proposing to require States to

implement a targeting strategy to more

aggressively monitor process sources

that are likely producing high

concentrations of SO2 even if for short

periods of time. As described

previously, the targeted strategy will be

implemented through the annual

SLAMS network review during which

the States will report on progress made

the previous year. The EPA believes that

the results of such a targeting strategy

will reduce the possibility and

frequency of 5-minute highconcentration SO2 exposures as an

incident to more effectively monitoring

peak SO2 concentrations and by

bringing into compliance those sources

violating the existing NAAQS. However,

EPA acknowledges that there may be

occurrences of SO2 releases which could

exceed the 5-minute NAAQS or section

303 trigger level proposed in the part

50/53 document and not exceed the

current SO2 NAAQS. In those cases, the

State should, nevertheless, conduct

compliance inspections in the

eventuality that the source is out of

compliance with current SIP

requirements. Beyond these measures,

EPA would not have authority to take

further actions under the title I SIP

program.

If violations of the current NAAQS

cannot be resolved through compliance

and enforcement (i.e., the source is in

compliance), then the State will be

expected to take steps to reduce

emissions on its own initiative by

revising the emission limit, by requiring

process modifications, or other control

measures. The State shall then prepare

a SIP revision for EPA approval in order

to make the emission reductions

federally enforceable. In the event that

a State does not take these steps, then

EPA can take either of two actions: (1)

If the area is currently designated

attainment, using the authority under

section 107(d) to redesignate the area

nonattainment; and/or (2) issuing a SIP

call under section 110(k)(5) of the Act

to notify the Governor of the State that

the SIP is inadequate to attain and

maintain the SO2 NAAQS and to call for

a SIP revision as necessary to correct

such inadequacies.

There are advantages and

disadvantages in using either the

nonattainment redesignation or SIP call

approach. For instance, the

nonattainment redesignation process, in

addition to requiring expeditious

attainment of the standard, imposes the

requirements applicable under part D,

title I, of the Act (e.g., reasonably

available control measures (RACM),

reasonable further progress (RFP),
Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules 12501

nonattainment NSR, and contingency

measures), and requires sanctions and

FIP’s if the SIP is not developed and

implemented in a timely manner.

While these part D requirements may

well be useful in effectively addressing

the air quality problem, plan

development may proceed more quickly

in response to a SIP call in some cases

because the SIP call does not entail the

process and time needed to undertake a

redesignation of an area (including the

notification of the Governor required

under section 107(d)(3)). The SIP

submitted in response to a SIP call

under section 110 must also provide for

expeditious attainment of the NAAQS.

A disadvantage of relying on SIP calls

for attainment areas is that, unless an

area is otherwise subject to section 173

permit requirements, no mandatory

sanctions are applicable in the event the

State fails to respond adequately to the

SIP call. The discretionary air grant

funding sanction under section 179

remains available for attainment areas,

however. The requirement for EPA to

promulgate a Federal plan if the State

fails to submit an approvable SIP is

wholly applicable for either option.

In addition to the advantages and

disadvantages just described, decisions

about which regulatory approach to use

should consider factors specific to the

affected area. Among the factors EPA

will consider are the following:

(1) The magnitude of the violation.

(2) The persistence of violations.

(3) The exposure potential. (For

example, is it near a population center

or a school?)

(4) The State’s regulatory process. (For

example, is it lengthy; does the

legislature only meet periodically?

Would the timeline of one option fit

better within the State’s regulatory

frame work?)

(5) Other sources in the area. (For

example, can culpability be clearly

determined? Would one process

facilitate that determination of

culpability over the other? Is new source

growth anticipated?)

(6) The need for a more objective level

of control.

(7) The type of information available

for indicating a problem exists

(monitoring, modeling, others).

(8) If there is uncertainty associated

with modeling and/or past history of

failing to attain the standard, does the

action taken provide for appropriate

contingencies that can be implemented

if the area fails to provide a SIP or to

attain and maintain the standards?

(9) Is there a need for long-range

planning for the area and does the

approach taken facilitate this planning

effort?

IV. Requirements Associated With

Retention of Existing NAAQS and

Implementation of a Section 303

Program

In attempting to address health

concerns with population exposure to

high concentrations of SO2 for short

periods of time, one of the alternatives

that EPA considered in the part 50/53

notice is to reaffirm the existing SO2

NAAQS and at the same time to

promulgate a trigger level for

implementation of a program under

section 303 of the Act. The basic

rationale and legal authority for that

program are discussed in that

document. What follows in more detail

is the proposed implementation

program, including the proposed

regulatory text. The EPA believes that a

targeted implementation strategy, as

already discussed, could be used to find

sources that would be subject to further

emissions or operational control under

a section 303 program. The EPA

believes that a program to protect the

public from exposure to high

concentrations of SO2 for short periods

of time may be successfully

implemented under section 303. The

type of program EPA is proposing to

implement would require States to

submit contingency plans to EPA that

would require certain actions on behalf

of the State and source once an

established ambient SO2 concentration

(‘‘trigger level’’) is violated. The State

would be required to take certain

actions to determine the source of the

emissions and to protect against future

violations of the trigger level.

As described in the part 50/53 notice

concerning the regulatory alternative of

the section 303 program, EPA believes

that sections 303, 110(a)(2)(G), and 301

provide adequate legal authority to

establish this program and to

promulgate regulations to implement it.

As with the existing section 303

program, EPA’s proposed regulations

require States to adopt contingency

plans under section 110(a)(2)(G) to carry

out the program. The EPA is proposing

to require that each State submit such

plans to EPA within 18 months of the

promulgation of final regulations

establishing a section 303 program. The

EPA believes that section 110(a)(2)(G)

authorizes EPA to require these

submissions and that 18 months is an

adequate period of time to develop and

submit the programs to EPA for

approval.

Once the section 303 trigger level has

been violated, EPA proposes that the

following actions occur. First, within 30

days of a violation of the trigger level,

the State would carry out a compliance

inspection of the culpable source. The

EPA recommends that the State not wait

for a violation but conduct a compliance

inspection after the first exceedance. If

the source is out of compliance with its

existing emission limits, then the State

would take the necessary steps to bring

the source into compliance within 30

days of the compliance inspection. If,

however, the State determines that

bringing the source into compliance

with its existing emission limits would

not be likely to prevent further

exceedances of the trigger level, or the

State determines the source to be in

compliance with applicable emission

limits, then further action would be

needed. In such circumstances, the next

step would be for the State and source

to examine the cause of the emissions.

Once that is determined, enforceable

actions would need to be developed to

address the cause of the pollution.

These actions must eventually be made

federally enforceable by adopting them

as source-specific SIP revisions. The

EPA proposes to require that actions be

taken within 60 days of the compliance

inspection and provide for

implementation of any new control

measures as expeditiously as

practicable. The EPA expects that the

control measures that may need to be

implemented to prevent recurrences of

5-minute SO2 peaks may include better

maintenance of control equipment,

better capture of fugitive emissions,

raising the stack height, or other

innovative control measures.

The EPA believes that the actions

required of States and sources would

provide adequate protection against the

recurrence of high, 5-minute SO2 peaks

once such emissions are identified as a

problem for particular sources. The EPA

also believes that the time periods for

taking action that it is proposing are

reasonable periods, as they provide

sufficient time for the required actions

to take place, while assuring that any

necessary corrective actions will be

taken and implemented as expeditiously

as practicable.

The EPA would also retain the ability

to take whatever actions it believed

appropriate directly under section 303.

Thus, EPA could take direct action

under section 303 prior to the adoption

of State contingency plans if needed, or

take action after their adoption if

circumstances warranted such Federal

action. Moreover, once the section 303

contingency plans have been adopted

and incorporated into SIP’s, EPA may

directly enforce their provisions

pursuant to section 113 of the Act.

However, it is EPA’s position that the

States are primarily responsible for

carrying out actions under this section
12502 Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules

303 program. If a State does not exercise

its responsibility under section 303 once

a trigger level has been violated, EPA

intends to consult with the State prior

to taking action itself.

The EPA is proposing to add an

Appendix X to 40 CFR part 51 which

explains the computations necessary to

determine from monitoring data

whether the 5-minute trigger level has

been exceeded or violated. Appendix X

defines several terms, among them, ‘‘5-

minute hourly maximum,’’

‘‘exceedance,’’ ‘‘expected exceedance,’’

and ‘‘violation.’’ Appendix X explains

the convention used to calculate

expected exceedances, which

essentially is a procedure which makes

an adjustment for missing monitoring

data.

In brief, the 5-minute trigger level is

not violated when the number of

expected exceedances per year is less

than or equal to one. In general, this

determination is made by recording the

number of 5-minute hourly maximum

exceedances at a monitoring site for

each year, making the adjustment for

missing data (if required), averaging the

number of exceedances over a 2-year

period, and comparing the number

calculated to the allowable number of

exceedances (one). The 2-year period

reduces the likelihood of a source being

penalized for a violation that may be

attributed to a one-time event. Aside

from changes in terminology to make

the language appropriate for a section

303 program rather than a NAAQS, the

proposed Appendix X is identical to the

Appendix I to 40 CFR part 50 for

interpreting the 5-minute NAAQS for

SO2 that was proposed in the part 50/

53 document. The EPA is soliciting

comments on Appendix X.

V. Requirements Associated With New

5-Minute SO2 NAAQS

The EPA proposed in the part 50/53

document a new primary 5-minute SO2

NAAQS which would be in addition to

the 24-hour and annual primary SO2

NAAQS. Should this new 5-minute

NAAQS be promulgated, EPA intends to

initiate the targeted implementation

strategy previously described to

determine which areas are not meeting

the new 5-minute NAAQS. In addition,

EPA and the States will need to initially

meet statutory requirements under

sections 107 and 110. In general, these

requirements are that the States must

submit their initial suggested

designations and statewide SIP’s to

EPA. Later, if areas are designated or

redesignated to nonattainment, then

EPA and the States must meet the

requirements under section 172. The

requirements under sections 107, 110,

and 172 of the Act are discussed in

detail below. The rationale for any

requirements which are discretionary,

such as setting timeframes, or which

need interpretation, are also discussed.

Since the current annual, 24-hour, and

3-hour NAAQS are retained under this

option, all existing requirements, such

as SIP submittal and attainment dates,

will remain in place as to the current

NAAQS.

A. Targeted Implementation Strategy

Should a new 5-minute NAAQS be

promulgated, EPA intends to initiate the

targeted implementation strategy

previously described to determine

which areas are not meeting the revised

5-minute NAAQS. And as described, the

States should initially attempt to

address any violations through

compliance inspection and, if necessary,

enforcement actions.

Because of the modeling issues

discussed previously (II.A.1.), the

targeted implementation strategy relies

principally on monitoring. The use of

models is not advocated at this time for

establishing section 107 designations

under a 5-minute SO2 NAAQS due to a

lack of evaluation results concerning

model performance, or defining the

precision and bias of modeled 5-minute

ambient SO2 concentrations. However,

models may still be used under a new

5-minute SO2 NAAQS program for the

following purposes:

(1) Models may be useful as a tool for

developing control strategies. When

evaluating emissions from complex

sources, they may provide information

on the relative contributions to ambient

SO2 concentrations from various sources

of emissions. Receptor modeling may be

a useful tool for developing control

strategies for complex sources. The use

of tracers or ‘‘tramp elements’’ in

association with these models would be

needed for SO2 emission sources to

determine source locations and relative

contributions to ambient SO2

concentrations.

(2) Models can be and are

recommended as a useful tool for

evaluating the design of monitoring

networks for a 5-minute SO2 standard.

They can provide useful information in

a relative sense for determining points

of maximum impact providing the

characteristics of the emission source

are not too complex or uncertain.

B. Designations—Section 107 

1. Statutory Requirements

The 1990 Amendments require EPA

to promulgate designations, of areas for

new or revised NAAQS. Section

107(d)(1)(A) of the Act requires States to

submit designations, and section

107(d)(1)(B) requires EPA to promulgate

designations of all areas (or portions

thereof) with respect to new or revised

NAAQS as nonattainment, attainment or

unclassifiable. The specific

requirements of section 107(d)(1) (A)

and (B) of the Act are described below.

An area which is designated

nonattainment is one that does not meet

(or that contributes to ambient air

quality in a nearby area that does not

meet) the NAAQS for the pollutant. An

area which is designated attainment is

one which meets the NAAQS for the

pollutant. An area which is designated

unclassifiable is one that cannot be

classified on the basis of available

information as meeting or not meeting

the NAAQS for the pollutant. Also,

while section 107(d)(1) provides for

States to submit a list of areas

designated, it authorizes EPA to modify

the designations submitted by the

States. Once an area’s initial designation

is promulgated, any change in the

designation status is accomplished

pursuant to section 107(d)(3) of the Act.

2. Timeframe for Submittal of

Designations by State

As mentioned above, section

107(d)(1)(A) of the Act requires States to

submit a list of all areas (or portions

thereof) in the State designating them as

nonattainment, attainment or

unclassifiable for SO2. States must

submit such list of areas (or portions

thereof) in a timeframe EPA deems

reasonable but not later than 1 year after

the effective promulgation date of the

new or revised NAAQS. The EPA

cannot require the States to submit the

list of areas in less than 120 days,

however.

The EPA intends to require that the

initial SO2 designations be submitted

not later than 1 year from the effective

date of promulgation of the revised

standard in order to allow the States as

much time as possible to gather the

necessary data to make the designation

determinations. The EPA believes that,

in most instances, areas will need to be

initially designated unclassifiable due to

lack of adequate ambient air monitoring

data and the inability to rely on models

for predicting 5-minute SO2

concentrations. By giving the maximum

time allowed under the Act, States may

have enough time to gather the data

needed to make an adequate

determination of an area’s designation

status. Nonetheless, EPA encourages

States to submit designations sooner,

wherever possible, in order to provide

improved protection of public health.
Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules 12503

3. Determining Initial Designation of an

Area

The EPA expects, in most instances,

to initially designate areas as

unclassifiable due to the lack of

complete data or no data at all reported

for 5-minute averaging time increments.

Most of the existing ambient monitoring

data are not reported for 5-minute

averaging time increments, and EPA

believes that those that are reported in

this manner may not meet the data

completeness criteria required by the

proposed SO2 NAAQS (see discussion

in revisions to CFR part 50, appendix I,

published in the part 50/53 document).

Revising the SO2 NAAQS to include an

additional primary standard set at 5-

minute and 0.60 ppm necessitates that

most ambient monitors be respanned to

measure the higher concentration.

In anticipation of a revised NAAQS,

EPA has requested that the States respan

monitors to begin measuring for higher

concentrations. In these cases, EPA and

States may have data to provide as a

basis for initially designating an area as

nonattainment.

The EPA understands that in some

instances States may want to request

that certain areas be initially designated

attainment for the revised SO2 NAAQS.

An area will not be initially designated

as attainment based solely on ambient

monitoring data since no requirements

have been issued to ensure complete

data. Data completeness is a significant

issue when trying to determine if an

area is attaining the NAAQS as opposed

to determining if an area is not attaining

the NAAQS. However, areas with no

SO2 sources as shown by their emission

inventory would be likely candidates for

an early attainment designation.

Providing ambient air monitoring data

does not indicate otherwise, EPA

intends to designate an area as

attainment if the State can show in its

emissions inventory that the area does

not contain any potential major source

of SO2 as defined in the Act. This does

not preclude the State or EPA from

initially designating an area

unclassifiable, if there is reason to

believe there is an SO2 source which

may be causing a violation of the

revised NAAQS in the area. The EPA

believes this guidance gives reasonable

assurance that the area is in attainment

of the revised NAAQS. This does not

prevent EPA or the State from

redesignating an area, initially

designated unclassifiable, to

nonattainment at a later time should

ambient air monitoring data indicate

that the area is violating the NAAQS.

4. Determining the Boundaries of

Designated Areas

States should identify the boundaries

of the nonattainment, attainment and

unclassifiable areas when submitting

designations for the revised SO2

NAAQS. In the absence of data or more

specific boundary information, it may

be more appropriate to define SO2

nonattainment boundaries by the

perimeter of the county in which the

ambient SO2 monitor(s) recording the

violation is located. Alternatively, it

might be appropriate to define the

nonattainment area using monitoring or

other data to determine more

specifically the geographic area that is

nonattainment. In addition, if the

ambient monitor measuring violations is

located near a county boundary, then

EPA recommends that the adjacent

county also be designated as

nonattainment for SO2. In some

situations, however, a boundary other

than the county perimeter may be

appropriate. States may choose,

alternatively, to define the SO2

nonattainment boundaries by using any

one, or a combination, of the following

techniques: (1) Qualitative analysis, (2)

spatial interpolation of air monitoring

data, (3) air quality simulation by

dispersion modeling, or (4) saturation

monitoring. If a State defines an SO2

nonattainment boundary using one of

the methods above, EPA requires that it

submit a defensible rationale for the

boundary chosen with the Governor’s

request to designate the area.

Boundaries for attainment areas can

be drawn along current political

boundaries if the State can show in its

emissions inventory that the area does

not contain any potential major source

of SO2 as defined in the Act, nor any of

the sources listed in the previous

section on determining the initial

designation of an area.

All areas of the State not designated

attainment or nonattainment will be

designated unclassifiable. The

boundaries of the unclassifiable area

will be the ‘‘remainder of the State.’’

5. Promulgation of Designations by EPA

Section 107(d)(1)(B)(i) of the Act

requires that EPA promulgate the

designations submitted by States as

expeditiously as practicable, but not

later than 2 years from the date of

promulgation of the revised SO2

NAAQS. This period may be extended

for up to 1 year where EPA has

insufficient information to promulgate

the designations. The EPA may make

any modifications deemed necessary to

the areas (or portions thereof) submitted

by the State (see generally section

107(d)(1)(B) of the Act). However, no

later than 120 days before promulgating

a modified area, EPA must notify the

affected State and provide an

opportunity for the State to demonstrate

why any proposed modification is

inappropriate.

The EPA expects in many cases to

require the full extension of 1 year

before promulgating the designations of

many areas as allowed under section

107(d)(1)(B) of the Act. The full

extension would be needed in these

cases in order to allow States and EPA

to respan or relocate monitors and

collect complete ambient data to better

ascertain the designation status of areas

with monitors. Therefore, EPA generally

intends to promulgate the initial area

designations within 3 years from the

effective date of promulgation of the

revised SO2 NAAQS.

Designations promulgated pursuant to

section 107(d)(1) of the Act are exempt

from the Administrative Procedures Act

requirements for notice-and-comment

rulemaking (5 U.S.C. section 553–557)

(see section 107(d)(2)(B) of the Act).

Therefore, when EPA promulgates

designations with respect to the revised

SO2 NAAQS, it may or may not

promulgate the designations through

notice-and-comment rulemaking.

6. Failing to Submit Designations

If the Governor of a State fails to

submit the required SO2 designations, in

whole or in part, EPA is required to

promulgate the designation that EPA

deems appropriate for any area (or

portion thereof) not designated by the

State (see section 107(d)(1)(B)(ii) of the

Act). The EPA will do so no later than

3 years after the date of promulgation of

a new NAAQS.

C. State Implementation Plans (SIP’s)

Section 110(a) establishes the general

requirements for SIP’s. In addition,

subparts 1 and 5 of part D of title I of

the Act establish additional

requirements concerning SIP’s for areas

designated nonattainment for SO2.

These requirements concern the content

of the SIP’s, the applicable dates by

which nonattainment areas must attain

a new SO2 NAAQS, and the schedule

for the submission of the SIP’s.

1. General SIP Requirements—Section

110(a)

All SIP’s, regardless of whether they

concern areas designated nonattainment

or not, must meet the general SIP

requirements of section 110(a). Section

110(a)(1) provides that each state must

submit a SIP to provide for the

implementation, maintenance and

enforcement of a primary NAAQS in
12504 Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules

1The statutory PSD requirements apply to new

major stationary sources and modifications of

existing major stationary sources. A ‘‘major

stationary source’’ is: (1) Any source from a

statutory list of 28 source categories that emits, or

has the potential to emit, 100 tons per year (tpy) or

more of a regulated pollutant; or (2) any other

source that emits, or has the potential to emit, at

least 250 tpy of a regulated pollutant (see section

169(1) of the Act).

2The EPA has also promulgated regulations for a

Federal PSD program at 40 CFR 52.21. The Federal

program applies to States that do not have EPAapproved PSD programs as part of their SIP.

3The PSD review requirements apply to any

regulated pollutant which a new or modified major

stationary source would emit in significant

amounts. Thus, a source may be ‘‘major’’ for only

one pollutant, but PSD review would apply to other

pollutants emitted in ‘‘significant’’ amounts.

each air quality control region within

the State (hereinafter referred to as

‘‘statewide SIP’s’’). Section 110(a)(2)

sets forth the elements that a SIP must

contain in order to be fully approved.

These elements are discussed in the

General Preamble for the

Implementation of Title I of the Clean

Air Act Amendments of 1990 (57 FR

13556–13557).

2. General SIP Requirements—Section

110(a)(2).

(a) Statutory and Existing Regulatory

Requirements. Regulations for the

preparation, adoption, and submission

of SIP’s under section 110 of the Act

were initially published November 25,

1971 (36 FR 22369) and codified as 40

CFR part 51. The 40 CFR part 51 has

been modified from time to time since

then. On November 7, 1986 (51 FR

40656), EPA restructured and

consolidated the 40 CFR part 51

regulations to make them easier to

follow and revise in the future.

The 1990 amended Act did not

substantially change the SIP

requirements in section 110(a)(2) of the

Act. For the most part, EPA believes that

the existing regulatory framework, i.e.,

40 CFR part 51, defines the general

section 110(a)(2) SIP requirements for

SO2. However, as a result of a revised

SO2 NAAQS, data handling practices,

and specified SIP submittal timeframes

in the Act, some revisions to 40 CFR

part 51 are necessary. The specific

revisions to 40 CFR part 51 are

discussed in another section entitled

‘‘Regulatory Revisions.’’ The EPA also

notes that under section 193, anything

in part 51 that is inconsistent with the

1990 Amendments is superseded even if

EPA has not yet revised the regulations.

A discussion of the statewide SIP

requirements is provided below.

(b) Statewide SIP’s for the Revised

SO2 NAAQS. For the most part, States

have already adopted, as part of their

overall SIP for current SO2 NAAQS,

rules or regulations which satisfy the

majority of the general SIP requirements

in section 110(a)(2) of the Act and the

existing 40 CFR part 51. At this time,

the EPA does not envision that States

will have to develop substantial new

general regulations for the statewide

SIP’s for the revised SO2 NAAQS. The

EPA will issue appropriate guidance in

the future in the event that this

assessment changes.

There are two requirements, in

particular, under section 110(a)(2) that

must be met by the States upon

promulgation of a revised SO2 NAAQS.

Section 110(a)(2)(B) requires the

establishment and operation of

appropriate ambient air monitoring

systems, data from which must be made

available to the Administrator upon

request. Coupled with this is a

requirement under section 110(a)(2)(E)

that States have adequate resources and

authority to implement the SIP.

(c) New Source Review Issues. Section

110(a)(2)(C) of the Act requires States to

protect the NAAQS by providing for the

regulation of the construction and

modification of stationary sources. In

areas that are designated as attaining the

NAAQS, as well as areas that are

designated as unclassifiable under

section 107 of the Act, each

implementation plan must contain

legally-enforceable requirements which

enable the State to determine whether

the construction or modification of

stationary sources will interfere with

maintenance of the NAAQS (see section

161 of the Act). For major stationary

sources that locate in attainment or

unclassifiable areas, the Act requires

that comprehensive preconstruction

review requirements under PSD of the

air quality program contained in part C,

title I, of the Act must be satisfied 1 (e.g.,

sections 160–169 of the Act).

The EPA has set forth SIP

requirements at 40 CFR 51.166

containing the minimum requirements

by which a State preconstruction review

permit program will be considered to

meet with the statutory requirements for

PSD.2 In very broad terms, these

requirements provide for the imposition

of best available control technology at

new and modified major stationary

sources for each pollutant subject to

regulation under the Act, and provide

for review of the potential air quality

impacts of such sources and

modifications (e.g., section 165(a) of the

Act).

The current PSD program

requirements under 40 CFR 51.166,

which protect the existing primary and

secondary NAAQS for SO2, will also be

protective of a new 5-minute SO2

NAAQS in that the regulations prevent

the issuance of a PSD permit to a major

source that would cause or contribute to

a violation of any NAAQS (§ 51.166(k)).

However, while no changes to the

existing requirements are needed to

ensure the new or modified PSD source

must evaluate their ambient impacts

against a new 5-minute standard for

SO2, EPA has reviewed certain existing

PSD provisions at § 51.166 (and

corresponding provisions at § 52.21) to

determine whether changes may be

needed to ensure that a new 5-minute

SO2 standard, as proposed in the part

50/53 document, would be adequately

protected.

Several of the existing PSD provisions

rely on Agency-prescribed significance

levels to determine whether any

pollutant that would be emitted by a

new or modified major stationary source

must undergo comprehensive permit

review. First, EPA uses significant

emissions rates (expressed in tons per

year) to determine whether a regulated

pollutant (other than a pollutant emitted

in major amounts) to be emitted by a

new or modified major stationary source

must undergo PSD review 3 (e.g.,

§ 51.166(b)(23)(i)).

Second, significant ambient impact

concentrations are used to determine

whether a source must undergo an

impact analysis to show that it will not

contribute to a violation of the NAAQS

or PSD increments (§ 51.165(b)). Finally,

significant monitoring concentrations

are used to determine whether the

reviewing authority may exempt a

source from the ambient monitoring

requirements for a particular pollutant

(e.g., § 51.166(i)(8)).

As described below, the EPA

examined each applicable significance

level used for SO2 in order to determine

whether a 5-minute standard for SO2

would necessitate any revisions to the

existing levels. In each case, EPA has

determined that sufficient information

is not presently available to warrant any

revision to the existing levels.

The significant emissions rate for SO2

is currently defined as an emissions rate

of 40 tpy or more under the PSD

regulations. New or modified sources

that would emit significant amounts of

SO2 must undergo PSD review for that

pollutant. Conversely, de minimis

amounts of SO2 emissions are exempt

from further review. The existing

significance level for SO2 is based on

the premise that an emissions rate that

would result in ambient concentrations

equaling at least 4 percent of the 24-

hour primary standard should be

considered significant (45 FR 52676,

52707–52708 (August 7, 1980)). In order

to help determine whether the existing
Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules 12505

4The PSD areas (areas designated as attainment

or unclassifiable under section 107 of the Act) are

further categorized as Class I, II, or III areas (section

162 of the Act). Each of these classifications

determines the ‘‘maximum allowable increases’’ or

increment of air quality deterioration permissible

(section 163 of the Act). Only a relatively small

increment of air quality deterioration is permissible

in Class I areas and consequently these areas are

afforded the greatest amount of air quality

protection. An increasingly greater amount of air

quality deterioration is allowed in Class II and III

areas.

Air quality deterioration is measured from the

date on which the first PSD application is

submitted. This date becomes the baseline date after

which any change in actual emissions affects the

allowable increment. In all instances, however, the

NAAQS represent the overarching air quality

ceiling that may not be exceeded, notwithstanding

any allowable increment.

significant emissions rate for SO2 would

be appropriate, based on the same

criteria, for the proposed 5-minute

standard, EPA would need to predict

the 5-minute concentration that results

from a source emitting 40 tpy of SO2.

The absence of an approved

methodology for either directly

modeling 5-minute SO2 concentrations

or converting modeled concentrations of

SO2 from a given averaging period (e.g.,

3-hour, 1-hour) to a 5-minute average

precludes EPA from completing its

analysis of the adequacy of the existing

significant emissions rate. Should EPA

adopt a 5-minute NAAQS for SO2, EPA

will further study the need for revisions

of the significant emissions rate.

Because of the present difficulties

associated with efforts to model 5-

minute ambient concentrations of SO2,

EPA has also determined that it would

be inappropriate to establish a

significant ambient impact level for a 5-

minute SO2 NAAQS. In the event that

adequate data and the appropriate

performance evaluations become

available to support the use of

dispersion models to estimate 5-minute

SO2 concentrations in the future, EPA

will consider the establishment of a 5-

minute SO2 significant ambient impact

concentration.

Under the existing regulations, the

reviewing authority may exempt a

proposed major stationary source from

the PSD pre-application monitoring

requirements (40 CFR 51.166(m)) if

either the air quality impacts resulting

from the source, or the existing ambient

concentrations of the particular

pollutant in the area of the source, are

less than the prescribed significance

level for that pollutant. For SO2, the

significance level is 13 μg/m3 (24-hour

average). Since models are not available

for a source to project its ambient

impact for 5-minute averaging periods,

EPA believes that consideration of a

new significance level for SO2 based on

a 5-minute averaging time is not

practical at this time. Instead, EPA

proposes to continue using the existing

24-hour significance level in

conjunction with the pre-application

monitoring requirement at 40 CFR

51.166(m). Thus, if a source finds that

it must gather ambient data for SO2,

based on ambient impacts and existing

air quality concentrations exceeding the

SO2 significance level, then the

applicant will be required to gather 5-

minute air quality data in addition to

data for all other applicable averaging

periods for SO2.

As indicated in the preceding

discussion, for several different PSD

program elements, EPA proposes to

retain existing SO2 significance levels

instead of pursuing the possibility of

revising the significance levels based on

a new 5-minute SO2 NAAQS. The EPA

requests the public’s views about this

proposed use of existing significance

levels.

The PSD program also includes

specific air quality limitations, known

as increments, which define maximum

allowable increases in pollutant

concentrations. These increments

prevent unlimited increases in ambient

pollutant concentrations beyond a

determined baseline concentration for a

particular area.4 Section 166 of the Act

authorizes EPA to promulgate new

increments within 2 years from the date

of promulgation of new NAAQS. The

existing PSD regulations include

increments for SO2 for the 3-hour, 24-

hour and annual averaging periods. The

EPA will determine the need for a 5-

minute increment for SO2, especially in

light of the present difficulties which

restrict the Agency’s ability to use air

quality dispersion models to determine

the amount of increment that would be

consumed by new and modified SO2

sources for a 5-minute averaging period.

The EPA will also investigate the

feasibility of developing and

implementing alternatives to numerical

air quality increments (expressed in μg/

m3), as authorized under section 166(d)

of the Act. In any event, EPA will not

propose new increments for SO2 until

such time that a new 5-minute SO2

NAAQS is first promulgated.

(d) Schedule for Submittal of Section

110(a)(1) SIP’s. Section 110(a)(1) states

that the SIP’s required by that

subsection are to be submitted to EPA

‘‘within 3 years (or such shorter period

as the Administrator may prescribe)

after the promulgation of a national

primary ambient air quality standard (or

any revision thereof) under section

109.’’ Such SIP’s are to provide for

‘‘implementation, maintenance and

enforcement’’ of the new NAAQS.

Section 110(a)(1), however, must be

read in light of the timetable for

designations of areas as nonattainment,

attainment, or unclassifiable under

section 107(d)(1) described above, and

the explicit timetables for SIP

submissions for nonattainment areas

under part D of title I. Section 107(d)(1)

provides that designations must occur

within 3 years of the promulgation of a

new NAAQS and the part D provisions

(sections 172(b) and 191(a)) provide for

the submission of SIP’s meeting the

requirements of section 172(c) within a

specified time period following the

designation of an area as nonattainment.

The EPA believes that these

provisions can best be harmonized in

the context of a new 5-minute SO2

NAAQS by interpreting the section

110(a)(1) deadline as being satisfied by

the submission of SIP elements whose

content does not depend on the

designation of an area. In the case of

SIP’s concerning a new 5-minute SO2

NAAQS, EPA believes that such

submissions would be limited to SIP

revisions concerning compliance with

the monitoring requirements of section

110(a)(2)(B) and the resource

requirements of section 110(a)(2)(E).

The EPA believes that, until a problem

with maintaining a new 5-minute

NAAQS is identified, it is reasonable to

view the already-existing substantive

SIP provisions as adequate and that it

would be absurd to require areas to

adopt additional control requirements

or emission limitations prior to the

identification of particular problem

sources. The EPA notes that any areas

designated nonattainment will be

subject to further SIP submission

deadlines requiring the submission of

nonattainment area SIP’s under part D

of title I that satisfy the substantive

requirements of section 172(c).

Moreover, with respect to the

monitoring and resource SIP elements,

EPA believes that any changes to

existing SIP’s that would be needed will

not be significant in terms of scope or

effort. Indeed, some States may have to

make minimal or no changes to their

own rules in order to implement the

new monitoring requirements. For this

reason, and because the changes in

monitoring requirements will assist in

developing information about ambient

air quality that will be relevant to

designations, EPA is proposing that all

States submit any needed SIP revisions

within 1 year of final action on today’s

proposal.

D. Nonattainment Area Requirements

Areas designated nonattainment must

meet the SIP requirements of part D of

title I as well as the requirements of

section 110. The provisions of part D
12506 Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules

pertinent to SO2 areas are those

contained in subparts 1 and 5. These

provisions have been described

previously in the General Preamble for

the Implementation of Title I of the

Clean Air Act Amendments of 1990 (57

FR 13498), and the following discussion

will focus on the requirements of

particular relevance to the

implementation of a new NAAQS.

1. Attainment and SIP Submittal Dates

To determine the attainment dates

and SIP submittal dates applicable to a

new SO2 NAAQS, it is necessary to

analyze the relationship of the relevant

provisions of both subpart 1 and subpart

5.

The starting point for the analysis is

section 172(a) in subpart 1. Section

172(a)(2)(A) provides that the

attainment date for attaining a primary

NAAQS is the date by which attainment

can be achieved as expeditiously as

practicable, but not later than 5 years

from the date of designation under

section 107(d). It also provides that EPA

may extend the attainment date to the

extent appropriate, for a period of up to

10 years after designation, considering

the severity of the air quality problem

and the feasibility and availability of

pollution control measures. Section

172(a)(2)(D), however, provides that

‘‘[t]his paragraph (paragraph (2)) shall

not apply with respect to nonattainment

areas for which attainment dates are

specifically provided under other

provisions of this part.’’ This language

therefore leads to the question of

whether areas designated nonattainment

with respect to a new SO2 NAAQS are

areas for which attainment dates are

provided elsewhere in part D of title I.

As subpart 5 establishes attainment

dates for certain SO2 nonattainment

areas, the issue is whether those

provisions establish attainment dates for

areas designated nonattainment with

respect to a new SO2 NAAQS. Of

particular relevance are sections 192(a)

and 191(a). Section 192(a) provides that

SIP’s required under section 191(a)

provide for attainment ‘‘as expeditiously

as practicable but no later than 5 years

from the date of the nonattainment

designation.’’ Section 191(a) requires

that ‘‘[a]ny State containing an area

designated or redesignated under

section 107(d) as nonattainment with

respect to the national primary ambient

air quality standards for sulfur oxides,

nitrogen dioxide, or lead subsequent to

the date of the enactment of the Clean

Air Act Amendments of 1990 shall

submit to the Administrator, within 18

months of the designation, an applicable

implementation plan meeting the

requirements of this part.’’

One possible interpretation of the Act

is that the language of section 191(a)

applies to areas designated

nonattainment with respect to a new

SO2 NAAQS promulgated after the

enactment of the 1990 Amendments. If

that interpretation is followed, section

192(a), rather than section 172(a)(2),

would determine the attainment date for

those areas. This is due to the language

in section 172(a)(2)(D) providing that

section 172(a)(2) does not apply to areas

for which attainment dates are

specifically provided elsewhere in part

D. The language of section 191(a), rather

than section 172(b), would also apply to

the establishment of the SIP submittal

date for nonattainment SIP’s required to

implement the new NAAQS. The

consequence of this interpretation for

the attainment deadline is that the 5-

year attainment deadline of section

192(a) would apply, rather than the 5-

year deadline that can be extended to 10

years under certain conditions under

section 172(a). As far as SIP submittal

deadlines are concerned, section

191(a)’s 18-month deadline would apply

rather than section 172(b)’s 3-year

deadline.

An alternative interpretation is that

the provisions of subpart 5 were

intended to apply only to attainment

dates and SIP submittal deadlines

concerning a NAAQS in existence at the

time of the enactment of the 1990 Clean

Air Act Amendments. Under this view,

the general provisions of subpart 1 (i.e.,

sections 172(a)(2)(A) and 172(b)) would

apply to the determination of attainment

dates and SIP submittal deadlines

pertaining to a new SO2 NAAQS

promulgated after the 1990

Amendments. The EPA notes, however,

that it believes that an 18-month SIP

submittal deadline would provide

adequate time for the States to develop

and submit their SIP’s regarding a new

NAAQS. It would also provide more

time to implement the control strategy

adopted in the SIP, which EPA believes

is preferable. If the maximum period of

3 years were allowed, there would only

be 2 years between the date of the

submittal of the SIP and the 5-year

attainment date, and even less time

between EPA’s final action regarding the

approvability of the SIP’s and the

attainment date. Consequently, even if

the provisions of section 172(b) were to

apply to SIP submittal deadlines for a

new NAAQS, EPA would require States

to submit their SIP’s within an 18-

month timeframe pursuant to section

172(b)’s authority to establish a shorter

period than the maximum 3-year period.

The EPA requests comment on both of

these interpretations and the

consequences that they lead to regarding

the establishment of attainment dates

and SIP submittal deadlines for a new

SO2 NAAQS.

2. Classifications—Section 172(a)(1)

The classification provisions (section

172(a)(1)) give EPA the authority to

classify nonattainment areas for the

purposes of applying attainment dates

(section 172(a)(2)(A)). In exercising this

authority, EPA may consider such

factors as the severity of the

nonattainment problem or the

availability and feasibility of the

pollution control measures. Based upon

the classification, EPA may set later

attainment dates for areas with more

severe air quality problems (section

172(a)(2)(A)).

At the present time, EPA does not

intend to establish a classification

scheme for areas which violate the new

5-minute SO2 NAAQS. Currently the

SO2 program does not have a

classification scheme since, typically,

within the SO2 program the severity of

the SO2 ambient air quality is not a

factor in attaining the NAAQS once the

needed control measures are put in

place. The EPA believes that in most of

the areas designated nonattainment for

the new 5-minute NAAQS, the cause of

the high SO2 concentrations (usually a

single source) will be obvious. While

the method of controlling these

emissions may not be as obvious, the

control measure should result, in most

cases, in a single step correction of any

future violations. Consequently, EPA

does not believe a classification scheme

is necessary or appropriate.

3. Nonattainment Plan Provision—

Section 172(c)

Section 172(c) lists the requirements

to be met by a nonattainment SIP. Some

of those requirements are discussed

below in the context of a SIP submittal

for a SO2 NAAQS nonattainment area.

a. Statutory and Existing Regulatory

Requirements. As previously indicated,

regulations for the preparation,

adoption, and submission of SIP’s were

initially published November 25, 1971

and codified as 40 CFR part 51. The 40

CFR part 51 has been modified from

time to time since then. However, the

most current guidance on how EPA

intends to interpret the 1990

Amendments is found in the General

Preamble (57 FR 13498, April 16, 1992).

The 1990 Amendments added section

172(c) which prescribes the

nonattainment SIP requirements. To the

extent that the existing SIP regulations

that have been codified in 40 CFR parts

51 and 52 do not conflict with section

172(c), EPA will rely on them to carry

out the requirements of section 172(c).
Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules 12507

5U.S. Environmental Protection Agency, Office of

Air Quality Planning and Standards, ‘‘Guidance

Document for Correction of Part D SIP’s for

Nonattainment Areas,’’ (Research Triangle Park,

North Carolina, January 27, 1984), page 27.

As necessary EPA will adopt new or

modify existing regulations to carry out

other provisions of section 172(c). For

further information on potential changes

to 40 CFR part 51 with respect to SO2,

see the separate section entitled

‘‘Regulation Revisions.’’ Also, as noted

earlier under section 193, anything in

part 51 that is inconsistent with the

1990 Amendments is superseded even if

EPA has not yet revised the regulations.

b. Reasonably Available Control

Measures (Including Reasonably

Available Control Technology). Section

172(c)(1) requires SIP’s to ‘‘provide for

the implementation of all reasonably

available control measures (RACM) as

expeditiously as practicable (including

such reductions in emissions from

existing sources as may be obtained

through the adoption, at a minimum, of

reasonably available control technology

(RACT)) and shall provide for

attainment of the national primary

ambient air quality standards.’’

Historically, EPA has defined RACT as

‘‘the lowest emission limit that a

particular source is capable of meeting

by the application of control technology

that is reasonably available considering

technological and economic feasibility

(Strelow, 1976).’’ In the case of a new 5-

minute SO2 NAAQS, EPA believes that

RACT should be interpreted in

accordance with EPA’s long-standing

interpretation.

The EPA notes that, as the sources of

any violations of a new SO2 NAAQS

should be readily identifiable, there

should not be any questions about the

identity of the sources to which RACT

should be applied. Thus, in the case of

a new SO2 NAAQS, compliance with

EPA’s general recommendation that

available control technology be applied

to those existing sources in the

nonattainment area that are reasonable

to control in light of the attainment

needs of the area and the feasibility of

such controls should be readily

achieved (EPA 1992c, n. 20, 57 FR

13541).

While a plan must require the

implementation of RACM needed to

attain within the statutory timeframes, it

need not require the adoption of all

available control measures if it

demonstrates attainment as

expeditiously as practicable without the

adoption of all measures. The EPA

believes it would be unreasonable to

require that a plan which demonstrates

attainment include all technologically

and economically available control

measures if such measures would not

expedite attainment. Thus, it is possible

that some available control measures

may not be ‘‘reasonably’’ available, and

not required by RACM, because their

implementation would not expedite

attainment (EPA 1992c, 57 FR 13543).

In addition to available control

technology that should be fully

considered in identifying RACT for

purposes of the current SO2 NAAQS,

RACT for purposes of a new 5-minute

NAAQS would also include

consideration of maintenance and

process operating procedures at SO2

sources that will achieve the new

NAAQS within the statutory

timeframes. The EPA believes that such

available control measures should be

fully assessed, in light of the general

guidance above, in determining RACM

(including RACT) for purposes of

implementing a 5-minute SO2 NAAQS.

c. Emission Inventory. Section

172(c)(3) states that the SIP shall

include a comprehensive, accurate,

current inventory of actual emissions

from all sources of SO2 in the

nonattainment area and that EPA may

require periodic revisions of the

inventory as determined necessary to

assure that the requirements of part D

are met. Typically for most

nonattainment areas, determining the

nature and extent of specific control

strategies needed requires an emissions

inventory. Also, typically, an emission

inventory should be based on measured

emissions or documented emission

factors. The more comprehensive and

accurate the inventory, the more

effective the control evaluation.

However, in terms of a new 5-minute

NAAQS, measured emissions or

emission factors for the probable

sources of 5-minute NAAQS

exceedances, process upsets, equipment

malfunctions, batch processes, startup/

shutdown, and fugitive emissions, are

almost nonexistent. It is anticipated that

most nonattainment areas for the 5-

minute SO2 NAAQS will be defined by

a single source as measured by a

monitor or monitors close to the source.

Thus, in most cases, the part D SIP for

a nonattainment area will fulfill the

inventory requirements of section

172(c)(3) by identifying the source

around which the monitors were located

and which may have caused the

monitored problem. In situations where

it is technically feasible, emission

estimates should be made using

emission measurements or factors.

d. Control Strategy Demonstration.

The EPA has historically required

dispersion modeling for setting

emission limits. However, because of

the limitations of models in predicting

5-minute concentrations, other methods

may have to be used. Control strategy

demonstrations may have to rely on

monitors as evidence of adequacy of the

implemented emission reductions as

being protective of the 5-minute

NAAQS. In certain cases, the monitors

may be used for setting the emission

limits. The EPA intends to rely on

section 11.2.2 of the Modeling

Guideline which addresses

requirements for using monitoring

networks to set emission limits.

e. Reasonable Further Progress. As

stated in the General Preamble (57 FR

13547), section 171(l) of the amended

Act defines reasonable further progress

as ‘‘such annual incremental reductions

in emissions of the relevant air pollutant

as are required by this part (part D) or

may reasonably be required by EPA for

the purpose of ensuring attainment of

the applicable national ambient air

quality standard by the applicable

date.’’ This definition is most

appropriate for pollutants which are

emitted by numerous and diverse

sources, where the relationship between

any individual source and the overall

air quality is not explicitly quantified,

and where the emission reductions

necessary to attain the NAAQS are

inventorywide. The definition is

generally less pertinent to pollutants

such as SO2, particularly for the

proposed new NAAQS, which usually

have a limited number of sources,

relationships between individual

sources and air quality which are

relatively well defined, and emissions

control measures which result in swift

and dramatic improvement in air

quality. That is, for SO2, there is usually

a single ‘‘step’’ between pre-control

nonattainment and post-control

attainment.

Therefore, for a new 5-minute SO2

NAAQS, with its discernible

relationship between emissions and air

quality and significant and immediate

air quality improvements, RFP will

continue to be construed as ‘‘adherence

to an ambitious compliance schedule.’’ 5

The compliance schedule for a new 5-

minute NAAQS could consist of

implementation of a maintenance

program where the source of emissions

is due to frequent malfunction of a

control device. The SIP’s which require

RFP as just described for an SO2

nonattainment area will be considered

as meeting the requirements of section

172(c)(2).

f. Permits for New and Modified Major

Stationary Sources. Section 172(c)(5) of

the Act states that the SIP shall require

permits for the construction and

operation of new or modified major

stationary sources (i.e., stationary
12508 Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules

6For purposes of the nonattainment NSR

requirements under part D of title I of the Act,

‘‘major stationary source’’ is defined as any

stationary source which emits, or has the potential

to emit, 100 tpy (or lesser amounts in certain

nonattainment areas) of any nonattainment

pollutant (see, e.g., sections 182(c–e), 189(b)(3), and

302(j) of the Act).

sources which emit or have the

potential to emit at least 100 tpy of any

nonattainment pollutant or lesser

amounts in certain nonattainment areas)

anywhere in a nonattainment area, in

accordance with section 173 of the Act.6

In nonattainment areas, a presumption

exists that emissions increases resulting

from new and modified major stationary

sources will adversely affect the area;

thus, in lieu of a complete air quality

impact analysis (including ambient

monitoring), emissions reductions

(offsets) from existing sources must be

obtained in order to mitigate the

ambient impacts resulting from the

potential emissions from the proposed

new source, or net emissions increase

from a proposed major modification to

an existing source (e.g., section 173(c) of

the Act).

Under the nonattainment NSR

program (40 CFR 51.165(a)), EPA uses

significant emissions rates (expressed in

tons per year) for pollutant applicability

purposes to determine whether a

modification of an existing major

stationary source will result in a

significant net emissions increase

(§ 51.165(a)(1)(x)). For the same reasons

described in section V.C of this

preamble, EPA does not now intend to

propose to revise the significant

emissions rate for SO2 commensurate

with the 5-minute SO2 NAAQS

proposed in the part 50/53 document.

Public comment is requested as to

whether the existing 40 tpy significant

emissions rate needs to be revised if

EPA promulgates the proposed 5-minute

SO2 standard.

Major new or modified sources

locating in the nonattainment area will

be required to meet the lowest

achievable emission rate, obtain

emissions offsets, and satisfy other

applicable requirements under section

173 of the Act. With implementation of

a new 5-minute NAAQS, these

requirements may be addressed by

existing permit programs for those areas

already designated nonattainment for

SO2 and meeting the nonattainment

NSR requirements under section 173 of

the Act. However, for those States

without the appropriate nonattainment

NSR program, the State would need to

develop and implement such a program

for any newly designated nonattainment

areas resulting from a new 5-minute

NAAQS for SO2.

g. Contingency Measures. Section

172(c)(9) of the amended Act defines

contingency measures as measures that

become effective without further action

by the State or EPA, upon determination

by EPA that the area has failed to: (1)

Make reasonable further progress, or (2)

attain the SO2 NAAQS by the applicable

statutory deadline.

For current SO2 programs, EPA

interprets ‘‘contingency measures’’ to

mean that the State agency has a

comprehensive program to identify

sources of violations of the SO2 NAAQS

and to undertake an aggressive followup

for compliance and enforcement,

including expedited procedures for

establishing enforceable consent

agreements pending the adoption of

revised SIP’s. The rationale for this

interpretation as presented in the

General Preamble (57 FR 13547) is the

following. The EPA interprets the

contingency measure provisions as

primarily directed at general programs

which can be undertaken on an

areawide basis. First, for some criteria

pollutants, the analytical tools for

quantifying the relationship between

reductions in emissions and resulting

air quality improvements remain subject

to significant uncertainties, in contrast

with procedures for pollutants such as

SO2 and its current NAAQS. Second,

emission estimates and attainment

analyses can be strongly influenced by

overly optimistic assumptions about

control efficiency and rates of

compliance for many small sources. In

contrast, controls for the current SO2

NAAQS are well understood and are far

less prone to uncertainty. Since SO2

control measures are by definition based

upon what is directly and quantifiably

necessary to attain the SO2 NAAQS, it

would be unlikely for an area to

implement the necessary emissions

control yet fail to attain the NAAQS.

However, for the proposed 5-minute

SO2 NAAQS, EPA will need to interpret

requirements for contingency measures

different from those for the current

NAAQS, due to the nature of sources

and emissions that EPA considers likely

to cause violations. As opposed to the

current NAAQS, which can rely on

dispersion models to predict attainment

of the NAAQS, the State and Local

agencies cannot reliably predict that

attainment will be achieved even with

proper implementation of a control

program. It is possible that even with

the control equipment operating

properly, violations may persist. In

other words, there may be overly

optimistic assumptions about control

efficiencies and emission rates.

Therefore, contingency measures for the

proposed 5-minute NAAQS will require

more than aggressive follow-up for

compliance and enforcement as allowed

for the current SO2 NAAQS. As an

example, if the cause of the SO2

violations is due to control equipment

failure, a SIP may require a more

rigorous maintenance schedule. If

further violations occur due to

continued failures of the control

equipment, then the contingency

measures may need to invoke a more

frequent inspection/maintenance

program of the control equipment or

even installation of backup control

equipment.

E. SIP Processing Requirements

1. SIP Completeness

Section 110(k)(1) required EPA to

promulgate minimum criteria that any

SIP submittal must meet. The EPA

proposed an initial set of completeness

criteria at 56 FR 23826 (May 24, 1991)

and finalized them at 56 FR 42216

(August 26, 1991). Those notices

describe the procedures for assessing

whether a SIP submittal is complete

and, therefore, adequate to trigger the

Act requirement that EPA review and

take action on the submittal. The

completeness criteria provide a

procedure and criteria that enable States

to prepare adequate SIP submittals and

enable EPA reviewers to promptly

screen SIP submittals, identify those

that are incomplete, and return them to

the State for corrective action without

having to go through rulemaking. The

EPA intends to use the completeness

criteria as amended in 40 CFR part 51,

appendix V, to determine completeness

of SIP submittals as required under

section 110(k)(1)(B).

2. Approval/Disapproval of Plan

The Act as amended in 1990 allows

for EPA to make full and partial

approvals and disapprovals under

section 110(k)(3) and conditional

approvals under section 110(k)(4) of SIP

submittals. In meeting the requirements

under section 110(k)(3) and (4), EPA

intends to follow the guidance for

processing SIP submittals issued in the

memo from Calcagni to the Regional Air

Division Directors dated July 9, 1992.

3. Sanctions and Other Consequences of

SIP Deficiencies

The EPA intends to use sanctions

consistent with the following stated

policies and regulations as provided for

by the Act in sections 110(m) and 179

for the imposition of sanctions in the

event that EPA finds that a State did not

make a required SIP submission (in

whole or in part), finds that a State did

not submit a complete submission,
Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules 12509

disapproves in whole or in part a

required submission, or finds that any

part of an approved SIP is not being

implemented. Section 179(a) provides

for the imposition of mandatory

sanctions unless the deficiency

identified by EPA (e.g., the failure to

submit or disapproval) is corrected

within 18 months. Moreover, section

110(m) provides EPA with the

discretionary authority to impose

sanctions at any time after a finding,

disapproval or determination under

section 179(a).

With respect to mandatory sanctions,

section 179(a) provides that unless the

State corrects the deficiency within 18

months, one of the two sanctions

referred to in section 179(b) (i.e.,

highway or offset sanctions) shall be

selected by EPA and will apply until

EPA determines that the State has come

into compliance. (In the case of a

finding of failure to submit a required

SIP revision, the sanctions would not be

lifted until EPA determines that the

State has submitted a SIP revision that

satisfies the completeness criteria.) If 6

months after the imposition of the first

sanction the State still has not corrected

the deficiency, then the second sanction

shall apply as well. If EPA finds a lack

of good faith on the part of the State,

then both the highway and offset

sanctions are applied 18 months after

the finding or disapproval.

The EPA has discussed in detail

issues concerning the imposition of

sanctions in a number of Federal

Register notices. The criteria for

imposing discretionary sanctions on a

statewide basis are discussed in a

February 11, 1994 Federal Register

notice, Criteria for Exercising

Discretionary Sanctions Under Title I of

the Clean Air Act (59 FR 1476), and are

codified at 40 CFR 52.30. The preamble

to this notice also sets forth EPA’s

policy with respect to section 110(m)

sanctions. Mandatory sanctions were

discussed in a October 1, 1993 proposal

(58 FR 51270) and in the August 4, 1994

final rule (59 FR 39832) selecting the

order of mandatory sanctions under

section 179. That final rule does not

apply to State failures to respond to SIP

calls. The EPA intends to address

sanctions for such failures in a future

rulemaking.

Apart from sanctions under sections

110(m) and 179(b), other consequences

may also attach to a failure to comply

with the Act’s SIP submission or

implementation requirements. First,

section 179(a) authorizes EPA to

withhold all or part of section 105

grants for air pollution control planning

and control programs. Second, section

110(c)(1)(B) provides that within 2 years

of a finding that a State has failed to

make a required submittal, a finding

that a required submittal was not

complete, or a disapproval of a

submission (in whole or in part), EPA

shall promulgate a FIP unless EPA

approves a submitted SIP that corrects

the deficiency. In support of this

requirement, EPA intends to use its

authority to withhold all or part of

section 105 grants to develop and

implement FIP’s where a State fails to

comply with the Act’s SIP submission

or implementation requirements.

VI. Significant Harm Levels and

Episode Criteria

In a notice published in the Federal

Register on April 26, 1988 (53 FR

14926), in which the EPA proposed not

to revise the SO2 NAAQS, the EPA at

the same time proposed to revise the

significant harm levels for SO2. Since

final action was never taken on that

proposal, EPA is reproposing to revise

the 24-hour significant harm levels.

Section 303 of the Act authorizes the

Administrator to take certain emergency

actions if pollution levels in an area

constitute ‘‘an imminent and substantial

endangerment to public health or

welfare, or the environment.’’ The Act

and EPA’s regulations governing

adoption and submittal of SIP’s (section

110(a)(2)(G) and 40 CFR 51.16 and

subpart H of part 51) require States to

adopt contingency plans to prevent

ambient pollutant concentrations from

reaching specified significant harm

levels and to take additional abatement

actions if such levels are reached. The

existing significant harm levels (40 CFR

51.16a) for SO2 were established in 1971

(36 FR 24002, November 21, 1971) at the

following levels: SO2 alone—1.00 ppm

(2620 μg/m3) 24-hour average of SO2;

and SO2 × tsp—490 × 103 (μg/m3) 2—

24-hour average product of SO2 and tsp

concentrations.

On the basis of EPA’s reassessment of

the data upon which these levels were

based and its assessment of more recent

scientific evidence on sulfur oxides and

particulate matter, EPA proposes to

revise the significant harm levels for

SO2.

In actions related to the revisions of

the particulate matter standards, EPA

has already eliminated the combined

tsp/SO2 significant harm level (52 FR

24672, July 1, 1987). In doing so, EPA

left open the possibility of reinstating an

SO2/PM–10 significant harm level, if

necessary for additional protection

against SO2 effects, at the conclusion of

the SO2 review. The scientific data

suggest that SO2 in combination with

high levels of particulate matter have

been associated with increases in daily

mortality. The final 24-hour PM–10

significant harm level of 600 μg/m3

takes this potential interaction into

account. Addition of a combined SO2/

PM–10 significant harm level therefore

appears unnecessary.

Removal of the combined significant

harm level raises the question as to

whether the remaining SO2 significant

harm level is sufficient. The possibility

that SO2 alone or in combination with

other pollutant or fog droplets may be

in part responsible for the effects

associated with 24-hour exposures

suggests the need to continue a 24-hour

significant harm level for SO2 alone at

a substantially lower concentration. The

EPA’s assessment of studies of daily

mortality (EPA, 1986a, Table 1 and EPA,

1986b Table 4–2) indicates greatest

certainty of some increased daily

mortality associated with high particle

concentrations in combination with SO2

levels at or above 750 μg/m3 (0.29 ppm)

for 24-hours. Accordingly, EPA

proposes to revise the 24-hour SO2

significant harm level from 1.0 (2,620

μg/m3) to 0.29 ppm (750 μg/m3).

Appendix L to part 51 contains

example air pollution episode levels

and example contingency plans for the

purpose of preventing air pollution from

reaching the significant harm levels

prescribed in section 51.151. The

examples in appendix L serve as guides

to States for the development of their

own contingency plans. To conform

with the proposed revisions to the

significant harm level for SO2, certain

changes to appendix L are required. The

EPA proposes the following revisions to

the example 24-hour episode levels for

SO2:

(1) That the example alert level for

SO2 be changed from 800 μg/m3 to 0.19

ppm (500 μg/m3), 24-hour average.

(2) That the example warning level for

SO2 be changed from 1600 μg/m3 to 0.23

ppm (600 μg/m3), 24-hour average.

(3) That the example emergency level

for SO2 be changed from 2100 μg/m3 to

0.26 ppm (675 μg/m3), 24-hour average.

The basis for changing the episode

levels for SO2 is the same as discussed

above for the revisions to the significant

harm level. With respect to example

episode levels, the proposed alert level

reflects the upper bound of the 24-hour

range of interest for the NAAQS

presented in the staff paper addendum

(EPA, 1986b, Table 2). The staff paper

concludes that at or above 0.19 ppm

(500 μg/m3) for 24 hours, health effects

are likely to occur in certain sensitive

population groups (EPA, 1982a, page

72). Therefore, it would be appropriate

under the episode criteria to initiate first

stage control action when this ambient

level of SO2 occurs. The proposed 24-
12510 Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules

hour warning and emergency levels are

set at increments between the proposed

alert level and the proposed significant

harm level. This approach would

provide opportunity for the control

actions associated with each episode

level to take effect before the next stage

is triggered and additional control

actions become necessary. This

proposal, if adopted, would change the

24-hour significant harm level.

Therefore, States would be required to

adopt the new numerical level, to

evaluate the emergency episode

provisions, in their current SIP’s and

any permits containing such provisions

and to make any revisions necessary to

assure their adequacy.

All public comments on the proposed

significant harm level and episode

criteria will be considered by the

Agency as it makes a decision on the

final significant harm level.

VII. Proposed Revisions to Part 58

Monitoring Regulations

The proposed revisions to 40 CFR part

58 are needed to allow States to reduce

in most cases the number of NAMS SO2

monitors in the metropolitan areas.

This, in turn, will free up monitors and

resources that can be used toward the

SO2 targeted implementation strategy.

The following preamble details

requirements which will be

implemented regardless of the

regulatory alternative that is ultimately

selected for part 50.

A. Section 58.1 Definitions

The number of SO2 monitors in the

revised NAMS network for major

metropolitan areas will be based on

factors including population, historical

ambient concentration measurements,

and total SO2 emissions. The SO2

emissions data are available from the

AIRS for each county and for each

consolidated metropolitan statistical

area/metropolitan statistical area

(CMSA/MSA). Therefore, the

requirements for NAMS SO2 stations

have been determined on a CMSA/MSA

basis, and the requirements for SLAMS

SO2 stations have been determined on a

county basis. Definitions are added for

CMSA and MSA as provided by the U.S.

Census Bureau.

B. Appendix C—Ambient Air Quality

Monitoring Methodology

As explained in a related notice in

this issue of the Federal Register that

proposes amendments to part 53,

continuous ambient air monitoring

analyzers designed to obtain 1-hour

average SO2 concentration

measurements may not provide accurate

5-minute average concentration

measurements. That notice proposes

special supplemental performance

specifications applicable to continuous

SO2 analyzers that would be used for 5-

minute monitoring so that the average

SO2 concentration measurements would

be accurate. A companion amendment

to appendix C of part 58 is needed to

specifically require the use of these

specially approved analyzers for 5-

minute monitoring in SLAMS

monitoring networks. Accordingly, a

new section 2.4 is proposed to require

that monitoring methods used for 5-

minute average SO2 measurements meet

the special supplemental specifications

proposed to be added to part 53.

C. Appendix D—Network Design for

State and Local Air Monitoring Stations

(SLAMS) and National Air Monitoring

Stations (NAMS)

Appendix D is being revised to

change the NAMS requirements for SO2

monitors. The present requirements are

based on measuring population

exposure over a large area without being

unduly influenced by point sources.

Because concentrations at a significant

number of these sites have decreased

over time and many are measuring

concentrations well below the current

SO2 NAAQS, EPA believes that they

may be put to better use if relocated.

The monitors which may be moved

could be used to complete the minimum

NAMS and SLAMS requirements or to

implement the targeted monitoring

strategy for point sources of SO2

emissions described earlier in this

notice (section II: Targeted

Implementation Strategy). Up to three

SO2 monitors would be required for

each metropolitan area for trends

purposes and general urban air quality

analyses. The new number of NAMS

monitors required for each metropolitan

area would be based on the combination

of population and SO2 emissions, as

defined in the Air Facility Subsystem of

AIRS and other information. The EPA

solicits comments on reducing the

requirements for the number of

population-oriented NAMS SO2

monitors in the metropolitan areas.

In addition to changing the criteria for

the required number of NAMS monitors

as noted above, new criteria are being

included for a minimum number of

SLAMS SO2 monitors for those counties

(or parts of counties) not a part of any

CMSA/MSA but with significant SO2

emissions. These counties with SO2

emissions greater than 20,000 tons/year,

as defined in the Air Facility Subsystem

of AIRS, would be required to have one

to two monitors. However, EPA is

proposing a provision which would

allow for a waiver of all (or part of)

these monitoring requirements after a 2-

year monitoring period in accordance

with EPA guidelines for network review

for source-oriented SO2 monitoring in

nonurban areas. Although these

guidelines have not been developed at

this time, EPA solicits comments on the

waiver provision criteria to be

established and included in the

guideline as well as the minimum

number of years for data collection. The

EPA also solicits comments on the

requirement for SO2 SLAMS monitors in

these areas.

As discussed earlier in this notice,

EPA believes there are a significant

number of sources of SO2 emissions

which can produce high 5-minute

ambient concentrations of SO2. These 5-

minute concentrations have the

potential to exceed the level for a

proposed 5-minute SO2 NAAQS or the

trigger level which may be established

under the authority of section 303 of the

Act. The sources which are believed to

provide these high concentrations

would be targeted for monitoring as

discussed earlier in this notice. States

will be required to prepare a targeted

SO2 monitoring plan containing a listing

of sources to be monitored, the schedule

for monitoring, and the rationale for

selecting the sources. The schedule for

monitoring should be as expeditious as

practicable. It is expected that the

resources which are made available by

the reconfiguration of the NAMS and

SLAMS networks will be used to

implement the targeting strategy around

selected SO2 sources. The targeted SO2

monitoring plan will be reviewed as

part of the annual network review.

The number of SO2 monitors to be

used around the targeted sources

depends on several diverse factors, i.e.

quantity of SO2 emissions, meteorology,

terrain, stack height and diameter of

stack, temperature and velocity of stack

emissions, distance from point of

emissions to fence line and populated

areas, batch operations, etc. To capture

high peak 5-minute concentrations may

require many monitors around the

sources (Sonoma Technology Inc.,

1994). However, it is not economically

feasible to place enough monitors

around the source to capture all

potential exceedances of the NAAQS or

trigger level. Therefore, EPA is using a

more moderate approach on the number

of monitors required.

The EPA is proposing a minimum

requirement of four SO2 monitors to

measure 5-minute, 3-hour, 24-hour, and

annual average SO2 concentrations

around the targeted sources. These

monitors could be point SO2 monitors,

open path SO2 analyzers, or a

combination of both. If open path
Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules 12511

analyzers with multiple monitoring

paths are used, each monitoring path

could potentially be substituted for one

point SO2 monitor. Modeling, and

perhaps saturation monitoring (a short

term study involving the use of portable

monitors deployed around the source),

could be used to determine the area of

expected maximum concentration based

on the most predominant wind

direction. One monitor would be placed

at the fence line downwind of the

predominant wind direction. A second

monitor would be placed in the

modeled maximum concentration area

based on the predominant wind

direction. Since wind directions around

an SO2 source may be significantly

different from one season to another,

this same procedure would be repeated

for the second most frequent wind

direction. For some cases, two or more

of these locations may coincide and

thereby reduce the number of monitors,

or allow for a State or local agency to

locate sites in alternative locations. In

other cases, additional monitors would

probably be needed for situations of

complex terrain and/or meteorology.

The EPA also encourages the use of

open path SO2 analyzers in combination

with point SO2 monitors to obtain better

spatial coverage around the targeted

sources. One open path SO2 analyzer

using multiple monitoring paths could

potentially replace several of the point

SO2 monitors, depending on factors

such as meteorology, terrain, and

obstructions. Open path analyzers may

be particularly useful in assessing

ambient SO2 concentrations over large

populated areas, such as parks and

recreation centers, where people are

expected to jog/exercise. The EPA

solicits comments on the location,

number and type of SO2 monitors, the

various available monitoring

technologies, and the need to waive

minimum monitoring requirements.

The concentration gradients are

expected to be sharper around these

targeted sources of SO2 emissions. As a

result, the SO2 monitors located to

measure population exposures over a

wide area are unlikely to adequately

characterize these peaks. Therefore,

appendix D is being revised to allow the

use of microscale SO2 sites for SLAMS

monitors, and to encourage middle/

neighborhood scale measurements as

appropriate in populated areas near

these targeted sources. The microscale

measurements for SO2 would represent

concentrations over an area ranging

from several meters to up to about 100

meters. The EPA solicits comments on

the use of micro, middle, and

neighborhood scale monitors, both point

monitors and/or open path analyzers,

around point sources of SO2 emissions.

The EPA is also proposing that the

SO2 monitors around these targeted

sources of SO2 emissions be classified as

SLAMS monitors. Section 2.3 requires

that monitoring be performed for a

minimum of 2 years. After that time, a

decision should be made during the

annual network review as to whether

the monitoring should be continued

around the targeted source, or the

monitors redeployed around a different

targeted source based on measured

concentration levels, changes in plant

process operations, etc. The EPA solicits

comments on the SLAMS classification

of the SO2 monitors around the targeted

sources and a waiver provision to

relocate the monitors before the full 2

years based on a review of the data.

With this proposal, EPA is also

requiring the collection of 5-minute SO2

concentrations at the targeted sites. The

EPA solicits comment on the need to

require 5-minute concentrations at

NAMS or other SLAMS sites, and if

supplementary criteria should be

considered for this additional request

(e.g., require 5-minute SO2 monitor data

if 1-hour concentration exceeds some

level).

D. Appendix F—Annual SLAMS Report

A proposed revision to section 2.1.1

of appendix F would reword this

section to provide greater clarity and

add a requirement to report the number

of 5-minute hourly maximum

observations. Section 2.1.2 would

similarly be reworded for clarity and to

require that the 24-hour averages

reported in the annual report for SO2 be

based on block (midnight to midnight)

averaging periods and the 3-hour

averages also to be based on block

averaging periods. Reporting of the

number of values in specified ranges of

24-hour average concentrations would

be deleted because of new revisions to

40 CFR part 58 data reporting

requirements.

Reporting of 5-minute hourly

maximums would also be added. The

EPA solicits comments on the need for

reporting additional summary data if a

multiple exceedance form of the

standard is adopted.

E. Appendix G—Air Quality Index

Reporting and Daily Reporting

The EPA proposes to revise the SO2

ambient concentrations contained in

Tables 1 and 2 and in Figure 3 to

correspond to the proposed new episode

criteria and significant harm levels.

VIII. Transition Issues

Since the existing NAAQS would be

retained even if a 5-minute NAAQS is

promulgated, all existing requirements

and attainment dates will remain in

place as to the existing NAAQS.

IX. Other Clean Air Act Amendment

Authorities Affecting SO2 Sources

The EPA is also developing a

voluntary program as part of the acid

rain program to encourage nonutility

sources to reduce their emissions of

SO2. The voluntary entry into the acid

rain program, known as the opt-in

program, allows nonaffected sources

(nonaffected under title IV), the

opportunity to receive their own

allowances, undertake emission

reductions and trade the extra

allowances they would no longer need

for compliance with the acid rain

program. Again, such participating

sources would be under the same

obligations to meet all other air

regulatory requirements.

These nonutility sources that could

participate in the opt-in program are the

same group of sources of concern for

establishing a 5-minute SO2 NAAQS.

Assuming entry occurred prior to the

imposition of the 5-minute standard, the

source could accelerate its emissions

reductions and offset the cost of such

reductions through participation in the

opt-in program. The EPA believes the

development of options for a 5-minute

SO2 standard and the opt-in program

protects public health and provides an

opportunity for cost reduction.

X. Public Participation

A. Comments and the Public Docket

The EPA welcomes comments on all

aspects of this proposed rulemaking.

Commenters are especially encouraged

to give suggestions for changing any

aspects of the proposal that they find

objectionable. All comments, with the

exception of proprietary information,

should be directed to Docket No. A–94–

55 with regard to part 51 and Docket No.

A–94–56 with regard to part 58 (see

ADDRESSES).

Commenters who wish to submit

proprietary information for

consideration should clearly separate

such information from other comments

by: (1) Labeling proprietary information

‘‘Confidential Business Information,’’

and (2) sending proprietary information

directly to the contact person listed (see

FOR FURTHER INFORMATION CONTACT) and

not to the public docket.

This will help ensure that proprietary

information is not inadvertently placed

in the docket. If a commenter wants

EPA to use a submission labeled as
12512 Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules

confidential business information as

part of the basis for the final rule, then

a nonconfidential version of the

document, which summarizes the key

data or information, should be sent to

the docket. Information covered by a

claim of confidentiality will be

disclosed by EPA only to the extent

allowed and by the procedures set forth

in 40 CFR part 2. If no claim of

confidentiality accompanies the

submission when it is received by EPA,

the submission may be made available

to the public without notifying the

commenters.

B. Public Hearing

Anyone who wants to present

testimony about this proposal at the

public hearing (see DATES) should, if

possible, notify the contact person (see

FOR FURTHER INFORMATION CONTACT) at

least 7 days prior to the day of the

hearing. The contact person should be

given an estimate of the time required

for the presentation of testimony and

notification of any need for audio/visual

equipment. A sign-up sheet will be

available at the registration table the

morning of the hearing for scheduling

those who have not notified the contact

earlier. This testimony will be

scheduled on a first-come, first-serve

basis to follow previously scheduled

testimony.

The EPA requests that approximately

50 copies of the statement or material to

be presented be brought to the hearing

for distribution to the audience. In

addition, EPA would find it helpful to

receive an advance copy of any

statement or material to be presented at

the hearing at least 1 week before the

scheduled hearing date. This is to give

EPA staff adequate time to review such

material before the hearing. Such

advance copies should be submitted to

the contact person listed.

The official records of the hearing will

be kept open for 30 days following the

hearing to allow submission of rebuttal

and supplementary testimony. All such

submissions should be directed to

Docket No. A–94–55 with regard to part

51 and Docket No. A–94–56 with regard

to part 58 (see ADDRESSES).

Joseph W. Paisie is hereby designated

Presiding Officer of the hearing. The

hearing will be conducted informally,

and technical rules of evidence will

apply. A written transcript of the

hearing will be placed in the above

docket for review. Anyone desiring to

purchase a copy of the transcript should

make individual arrangements with the

court reporter recording the proceeding.

XI. Administrative Requirements

A. Regulatory Impact Analysis

Under Executive Order 12866, (58 FR

51735 (October 4, 1993)) the Agency

must determine whether the regulatory

action is ‘‘significant’’ and therefore

subject to the Office of Management and

Budget (OMB) review and the

requirements of the Executive Order.

The Order defines ‘‘significant

regulatory action’’ as one that is likely

to result in a rule that may:

(1) Have an annual effect on the

economy of $100 million or more or

adversely affect in a material way the

economy, a sector of the economy,

productivity, competition, jobs, the

environment, public health or safety, or

State, local, or tribal governments or

communities.

(2) Create a serious inconsistency or

otherwise interfere with an action taken

or planned by another agency.

(3) Materially alter the budgetary

impact of entitlements, grants, user fees,

or loan programs or the rights and

obligations of recipients thereof.

(4) Raise novel legal or policy issues

arising out of legal mandates, the

President’s priorities , or the principles

set forth in the Executive Order.

Pursuant to the terms of Executive

Order 12866, it has been determined

that this rule is a ‘‘significant regulatory

action’’ because of its potential to have

an annual effect on the economy of $100

million or more as discussed in the

related SO2 NAAQS proposal package

on November 15, 1994 (59 FR 58958).

As such, this action was submitted to

OMB for review. Changes made in

response to OMB suggestions or

recommendations will be documented

in the public record.

The EPA has prepared a draft

regulatory impact analysis (RIA) based

on information developed by several

EPA contractors. It includes estimates of

costs, benefits, and net benefits

associated with alternative SO2 NAAQS.

The draft analysis, entitled Regulatory

Impact Analysis of the National

Ambient Air Quality Standards for SO2–

Draft, is available from the address

given above. The draft RIA estimates the

cost for the short-term SO2 NAAQS

regulatory alternative. The cost estimate

for the short-term SO2 NAAQS

alternative represent a snapshot of the

estimated total industry costs that could

be incurred at some unspecified time in

the future following full implementation

of a short-term SO2 NAAQS. The costs

are based on the use of add-on control

devices and fuel switching to lowersulfur fuels. Given that EPA believes

that many sources will be able to reduce

their peaks through other,

nontechnological means, this

assumption may result in overstating

costs. With this caveat in mind,

nonutility annualized costs are

estimated to be approximately $250

million for an ambient SO2

concentration for a 0.06 ppm, 5 annual

exceedance concentration levels are

estimated to be approximately $160

million. It is estimated that SO2 will be

reduced by approximately 910,000 tons,

and 560,000 tons for 1 and 5 exceedance

cases, respectively. Incremental to the

title IV requirements and attainment of

the existing SO2 NAAQS, total utility

annualized costs in 2005 are estimated

to be an additional $1.5 billion for the

0.06 ppm, 1 expected exceedance case,

and $400 million for the 5 expected

exceedance case. Estimated total utility

SO2 emissions in 2005 are not expected

to change given the title IV emissions

trading program.

Administrative costs are estimated to

be approximately $18 million for the

short-term NAAQS regulatory

alternative. Monitoring costs are

estimated to be minimal.

However, EPA has not completed its

cost analysis of the section 303

regulatory alternative which EPA

believes will be less than the SO2

NAAQS regulatory alternative. The EPA

intends to complete this analysis and

make it available to the public by the

end of January 1995. The EPA will

announce the availability of this

analysis in the Federal Register as soon

as it is available. A final RIA will be

issued at the time of promulgation of

final standards. Neither the draft RIA

nor the other contractor reports have

been considered in issuing this

proposal.

The regulations, implementation of

the revised SO2 NAAQS, the retained

existing NAAQS, and the section 303

program, have been submitted to OMB

for review under Executive Order

12866. Any written comments from

OMB and any EPA responses to those

comments are in the public docket for

this rulemaking.

B. Impact on Reporting Requirements

Air quality monitoring activities that

would occur as a result of the SO2

NAAQS proposal could increase the

costs and man-hour burdens to State

and local agencies for conducting

ambient SO2 surveillance required by 40

CFR part 58 and currently approved

under OMB Control Number 2060–0084.

Temporarily-increased costs could

result from the relocation of some

monitors currently operated as part of

the SLAMS networks and from the

purchase and operation of additional

monitors in a small number of agencies.
Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules 12513

However, some or all of these costs

could be offset by savings in existing

monitoring networks. As a result, to the

extent that additional monitoring costs

will be incurred at all, EPA expects that

these costs will be minimal.

The information collection

requirements in this proposed rule have

been submitted for approval to OMB

under the Paperwork Reduction Act, 44

U.S.C. 3501 et seq. An Information

Collection Request document has been

prepared by EPA (ICR No.0940.11) and

a copy may be obtained from Sandy

Farmer, Information Policy Branch,

EPA, 401 M St., S.W. (Mail Code 2136),

Washington, DC 20460, or by calling

(202) 260–2740.

Send comments regarding the burden

estimate or any other aspect of this

collection of information, including

suggestions for reducing this burden to

Chief, Information Policy Branch, EPA,

401 M St., S.W. (Mail Code 2136),

Washington, DC 20460, and to the

Office of Information and Regulatory

Affairs, Office of Management and

Budget, Washington, DC 20503, marked

‘‘Attention: Desk Officer for EPA.’’ The

final rule will respond to any OMB or

public comments on the information

collection requirements contained in

this proposal.

C. Impact on Small Entities

Under the Regulatory Flexibility Act,

5 U.S.C., 600 et seq, the Agency must

prepare a regulatory flexibility analysis

assessing the impact of any proposed or

final rule on small entities. Under 5

U.S.C. 605(b), this requirement may be

waived if the Agency certifies that the

rule will not have a significant

economic effect on a substantial number

of small entities. Small entities include

small businesses, small not-for-profit

enterprises, and governmental entities

with jurisdiction over populations of

less than 50,000.

A decision to revise the current

NAAQS for SO2 or set a trigger level for

implementation of a section 303

program would impose no new major

requirements. It is expected that

following the promulgation of a revised

SO2 NAAQS, additional nonattainment

areas will be designated and will thus

have to submit SIP revisions imposing

additional control requirements on

affected sources.

Furthermore, the control measures

necessary to attain and maintain the

NAAQS or implement a section 303

program are developed by the respective

States as part of their SIP’s. In selecting

such measures, the States have

considerable discretion so long as the

mix of controls selected is adequate to

attain and maintain the NAAQS or not

exceed the section 303 trigger level.

Whether a particular NAAQS would

have a significant effect on a substantial

number of small entities, therefore,

depends on how the States would

choose to implement it. For these

reasons, any assessment performed by

EPA on the costs of additional SIP

requirements at this time would

necessarily be speculative. On the basis

of the above considerations and

findings, and as required by section 605

of the Regulatory Flexibility Act, 5

U.S.C. 601 et seq., the Administrator

certifies that this regulation does not

have a significant impact on a

substantial number of small entities.

D. Reduction of Governmental Burden

Executive Order 12875 (‘‘Enhancing

the Intergovernmental Partnership’’) is

designed to reduce the burden to State,

local, and tribal governments of the

cumulative effect of unfunded Federal

mandates. The Order recognizes the

need for these entities to be free from

unnecessary Federal regulation to

enhance their ability to address

problems they face and provides for

Federal agencies to grant waivers to

these entities from discretionary Federal

requirements. The Order applies to any

regulation that is not required by statute

and that creates a mandate upon a State,

local, or tribal government. The EPA is

required by statute to review

periodically and, as necessary, revise

the national ambient air quality

standards, and to call on States to

develop plans to attain and maintain

these standards. However, this action

also includes a request for comment on

the adoption of a section 303 program,

as well as a proposal to establish a

targeted monitoring network, neither of

these actions is explicitly mandated by

statute. Therefore, in accordance with

the purposes of Executive Order 12875,

EPA will consult with representatives of

State, local, and tribal governments to

inform them of the requirements for

implementing the alternative regulatory

measures being proposed to address

short-term peak SO2 exposures. The

EPA will summarize the concerns of the

governmental entities and respond to

their comments prior to taking final

action.

The EPA anticipates that there will be

no additional cost burden imposed on

States in order to implement the

monitoring requirements proposed in

this notice. In general, costs incurred for

relocating monitors will be offset by

operating costs saved from

discontinuing SLAMS and NAMS

monitors. For more detail the reader is

referred to the section on resource

concerns for relocating monitors under

the targeted implementation strategy

section discussed earlier in this notice

or to the supporting statement for the

information collection request.

E. Environmental Justice

Executive Order 12898 requires that

each Federal agency shall make

achieving environmental justice part of

its mission by identifying and

addressing, as appropriate,

disproportionately high and adverse

human health or environmental effects

of its programs, policies, and activities

on minority and low-income

populations. The requirements of

Executive Order 12898 have been

addressed in the draft RIA cited above.

On average, approximately 25 percent

of the total population and 14 percent

of total households residing in

geographic areas that are potentially

impacted by short-term SO2 peaks of

0.60 ppm or greater are nonwhite and

below the poverty level, respectively.

These estimates exceed the national

averages of 19.7 percent and 12.7

percent, respectively. It also follows

that, on average, 25 percent of the

asthmatics potentially exposed to shortterm SO2 peaks of 0.60 ppm or greater

are nonwhite. Upon closer examination,

44 percent of these potentially SO2-

impacted areas have a nonwhite

population greater than the national

average with 24 percent between 1 and

2 times greater, 10 percent between 2

and 3 times greater, 7 percent between

3 and 4 times greater, and 3 percent

between 4 and 5 times greater.

Appendix A—References

Bennett, K.M. (1982), US EPA, Assistant

Administrator for Air, Noise and

Radiation, Policy on Excess Emissions

During Startup, Shutdown, Maintenance,

and Malfunctions, Memorandum to

Regional Administrators, Regions I-X,

September 28, 1982.

Burton, C.S.; Stoeckenius, T.E.; Stocking,

T.S.; Carr, E.L.; Austin, B.S.; Roberson,

R.L. (1987), Assessment of exposures of

exercising asthmatics to short-term SO2

levels as a result of emissions from U.S.

fossil-fueled power plant, Systems

Applications, Inc., San Rafael, CA., Pub.

No. 87/176, September 23, 1987.

Calcagni, J. (1992), Director of Air Quality

Management Division, Processing of

State Implementation Plan (SIP)

Submittals, Memorandum to Air

Division Directors, Regions I-X, July 9,

1992.

EPA (1982a), Review of the National Ambient

Air Quality Standards for Sulfur Oxides:

Assessment of Scientific and Technical

Information-OAQPS Staff Paper, Office

of Air Quality Planning and Standards,

Research Triangle Park, NC, EPA–450/5–

82–007.
12514 Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules

EPA (1986a), Second Addendum to Air

Quality Criteria for Particulate Matter

and Sulfur Oxides (1982): Assessment of

Newly Available Health Effects

Information, Environmental Criteria and

Assessment Office, Research Triangle

Park, NC, EPA–450/5–86–012.

EPA (1986b), Review of the National

Ambient Air Quality Standards for

Sulfur Oxides: Updated Assessment of

Scientific and Technical Information,

Addendum to the 1982 OAQPS Staff

Paper, Office of Air Quality Planning and

Standards, Research Triangle Park, NC,

EPA–450/05–86–013.

EPA (1986c), Guideline on Air Quality

Models (Revised), Office of Air Quality

Planning and Standards, Research

Triangle Park, NC, EPA–450/2–78–027R.

(Codified in 40 CFR 51, appendix W.)

EPA (1992a), National Air Pollutant Emission

Estimates, 1900–1991, Office of Air

Quality Planning and Standards,

Research Triangle Park, NC, EPA–454/R–

92–013.

EPA (1992b), National Air Quality and

Emissions Trends Report, 1991, Office of

Air Quality Planning and Standards,

Research Triangle Park, NC, EPA/450–R–

92–001.

EPA (1992c), General Preamble for the

Implementation of Title I of the Clean

Air Act Amendments of 1990, April 16,

1992, 57 FR 13498.

EPA (1994b), Review of the Ambient Air

Quality Standards for Sulfur Oxides:

Updated Assessment of Scientific and

Technical Information, Supplement to

the 1986 OAQPS Staff Paper Addendum,

Office of Air Quality Planning and

Standards, Research Triangle Park, NC,

EPA/452/R–94–013.

Polkowsky, B. (1991), U.S. EPA, Standards

Development Section, Analysis of Utility

Emissions Limits for Short-term SO2

NAAQS, Memorandum to John Haines,

Chief, Standards Development Section,

August 2, 1991.

Rosenbaum, A.S.; Hudischewskyj, A.B.;

Roberson, R.L.; Burton, C.S. (1992),

Estimates of Future Exposures of

Exercising Asthmatics to Short-term

Elevated SO2 Concentrations Resulting

from Emissions of U.S. Fossil-fueled

Power Plants: Effects of the 1990

Amendments to the Clean Air Act and a

5-minute Average Ambient SO2

Standard, Pub. No. SYSAPP–92/016,

April 23, 1992.

Sonoma Technology Inc. (January 1994),

Recommendations for the Use of OpenPath and Fixed-Point Monitors for

Determining Ambient SO2

Concentrations, Final Report STI–94021–

1402–FR, Prepared for U. S.

Environmental Protection Agency,

Research Triangle Park, NC.

Strelow, R. (1976), U.S. EPA, Assistant

Administrator, Air and Waste

Management, Guidance for Determining

Acceptability of SIP Regulations in Nonattainment Areas, Memorandum to

Regional Administrators, Regions I-X,

December 9, 1976.

Stoeckenius, T.E.; Garelick, B.; Austin, B.S.;

O’Connor, K.; Pehling, J.R. (1990),

Estimates of Nationwide Asthmatic

Exposures to Short-term Sulfur Dioxide

Concentrations in the Vicinity of

Nonutility Sources. Systems Application

Inc., San Rafael, CA, Publication Number

SYSAPP–90/129, December 6, 1990.

List of Subjects in 40 CFR Parts 51 and

58

Environmental protection,

Administrative practices and procedure,

Air pollution control, Intergovernmental

relations, SO2, Reporting and

recordkeeping requirements, State

implementation plans.

Dated: February 15, 1995.

Carol M. Browner,

Administrator.

For the reasons set forth in the

preamble, EPA proposes to amend

chapter I of title 40 of the Code of

Federal Regulations as follows:

PART 51—REQUIREMENTS FOR

PREPARATION, ADOPTION, AND

SUBMITTAL OF IMPLEMENTATION

PLANS

1. The authority citation for part 51

continues to read as follows:

Authority: 42 U.S.C. 7401(a)(2), 7475(e),

7502 (a) and (b), 7503, 7601(a)(1) and 7602.

2. In § 51.151 of subpart H, the entry

for ‘‘Sulfur dioxide’’ is revised to read

as follows:

§ 51.151 Significant harm levels.

* * * * *

Sulfur dioxide—0.29 parts per million (750

micrograms/cubic meter), 24-hour average.

* * * * *

3. In appendix L to part 51,

paragraphs 1.1 (b), (c), and (d) are

amended by revising the entries for

‘‘SO2’’ to read as follows:

Appendix L to Part 51—Example

Regulations for Prevention of Air

Pollution Emergency Episodes

* * * * *

1.1 * * *

(b) * * *

SO2—0.19 ppm (500 μg/m3), 24-hour

average.

* * * * *

(c) * * *

SO2—0.23 ppm (600 μg/m3), 24-hour

average.

* * * * *

(d) * * *

SO2—0.26 ppm (675 μg/m3), 24-hour

average.

* * * * *

Subpart T—Conformity to State or

Federal Implementation Plans of

Transportation Plans, Programs, and

Projects Developed, Funded or

Approved Under Title 23 U.S.C. or the

Federal Transit Act

4. Section 51.465 is added to Subpart

T to read as follows:

§ 51.465 Contingency plans.

(a) Each plan must include a

contingency plan which must, as a

minimum, provide for taking action

necessary to prevent further violations

of the 5-minute trigger level for sulfur

dioxide (SO2) attributable to emissions

from a source once one exceedance has

occurred. The 5-minute trigger level is

0.60 parts per million (ppm), not to be

exceeded more than once per calendar

year, as determined in accordance with

appendix Y to this part.

(b) Each contingency plan must

provide that:

(1) Within 30 days of determination of

a violation of the trigger level, the State

shall carry out a compliance inspection

of any source whose emissions may

have resulted in or contributed to the

violation of the trigger level.

(2) If the source is out of compliance

with applicable SO2 emission limits

then, within 30 days of completing the

compliance inspection in paragraph

(b)(1) of this section, the State shall take

enforcement action to bring the source

into compliance.

(3) If the source is in compliance with

applicable SO2 emission limits then,

within 60 days of completing the

compliance inspection in paragraph

(b)(1) of this section, the State shall

develop and implement an enforceable

emission reduction plan with a

compliance schedule to address the

cause of the emissions producing the

trigger level violation. The schedule

shall provide for implementation of all

actions necessary to prevent further

violations of the trigger level as

expeditiously as practicable. This

emission reduction plan must be

submitted to EPA as a revision to their

State implementation plan within 1 year

of completing the compliance

inspection in paragraph (b)(1) of this

section.

(4) If in carrying out the compliance

inspection referred to in paragraph

(b)(1) of this section, the State

determines that the source is out of

compliance with its applicable SO2

emission limits but also determines that

bringing the source into compliance

with its applicable emission limits

would not be likely to prevent further

exceedances of the trigger level, then the

State and source shall develop and
Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules 12515

1U.S. Bureau of the Census, ‘‘Statistical Abstract

of the United States: 1993’’, (113th Edition),

Washington, DC (1993).

implement an emission reduction plan

as described in paragraph (b)(3) of this

section.

5. Appendix Y is added to part 51 to

read as follows:

Appendix Y to Part 51—Interpretation

of the 5-Minute Trigger Level for Sulfur

Dioxide

1.0 General

a. This appendix explains the

computations necessary for analyzing sulfur

dioxide data to determine whether the 5-

minute trigger level specified in § 51.400(a),

subpart T, has been exceeded and whether

the 5-minute trigger level has been violated.

Sulfur dioxide is measured in the ambient air

by the reference method specified in

appendix A of this part or an equivalent

method designated in accordance with part

53 of this chapter.

b. Several terms used in this appendix

must be defined. A ‘‘5-minute hourly

maximum’’ for SO2 refers to the highest of

the 12 possible nonoverlapping 5-minute SO2

averages calculated or measured during a

clock hour. The term ‘‘exceedance’’ of the 5-

minute trigger level concentration means a 5-

minute hourly maximum value that is greater

than the 5-minute trigger level after rounding

to the nearest hundredth ppm (i.e., values

ending in or greater than 0.005 ppm are

rounded up; e.g., a value of 0.605 would be

rounded to 0.61, which is the smallest value

for an exceedance). The term ‘‘year’’ refers to

a calendar year. The term ‘‘quarter’’ refers to

a calendar quarter. The 5-minute SO2 trigger

level is expressed in terms of the number of

expected exceedances per year by adjusting

for missing data (if required) and by

averaging over a 2-year period.

2.0 Trigger Level Determination

a. The 5-minute trigger level is not violated

when the number of expected exceedances

per year is less than or equal to one. In

general, this determination is to be made by

recording the number of 5-minute hourly

maximum exceedances at a monitoring site

for each year, using the calculations in

section 3.2 to compensate for missing data (if

required), averaging the number of

exceedances over a 2-year period, and

comparing the number of exceedances

(rounded to the nearest integer) to the

number of allowable exceedances.

b. Although it is necessary to meet the

minimum data completeness requirements to

use the computational formula described in

section 3.2, this criterion does not apply

when there are obvious exceedance

situations which contribute to a violation.

For example, when a site fails to meet the

completeness criteria, violation of the 5-

minute trigger level can still be established

on the basis of the observed number of

exceedances in a year (e.g., three observed

exceedances in a single year).

3.0 Calculations for the 5-Minute Trigger

Level

3.1 Calculating a 5-Minute Hourly

Maximum

A 5-minute hourly maximum value for SO2

is the highest of the 5-minute averages from

the 12 possible nonoverlapping periods

during a clock hour. These 5-minute values

shall be rounded to the nearest hundredth

ppm (fractional values equal to or greater

than 0.005 ppm are rounded up). A 5-minute

maximum shall be considered valid if: (1) 5-

minute averages were available for at least 9

of the 12 5-minute periods during the clock

hour, or (2) the value of the 5-minute average

exceeds the level of the 5-minute trigger

level.

3.2 Calculating Expected Exceedances for a

Year

a. Because of practical considerations, a 5-

minute maximum SO2 value may not be

available for each hour of the year. To

account for the possible effect of incomplete

data, an adjustment must be made to the data

collected at a particular monitoring location

to estimate the number of exceedances in a

year. The adjustment is made on a quarterly

basis to ensure that the entire year is

adequately represented. In this adjustment,

the assumption is made that the fraction of

missing values that would have exceeded the

trigger level is identical to the fraction of

measured values above this level.

b. For all NAMS and SLAMS sites that

report 5-minute SO2 data, the computation

for incomplete data is to be made for all sites

with 50 to 90 percent complete data in each

quarter. If a site has more than 90 percent

complete data in a quarter, no adjustment for

missing data is required. If a site has less

than 50 percent complete data in a quarter,

no adjustment for missing data is required

and the observed exceedances are used.

c. The estimate of the expected number of

exceedances for the quarter is equal to the

observed number of exceedances plus an

increment associated with the missing data.

1. The following formula must be used for

these computations:

eq=vq+[(vq/nq)×(Nq¥nq]=vq×Nq/nq [1]

Where:

eq=the expected number of exceedances for

quarter q,

vq=the observed number of exceedances for

quarter q,

Nq=the number of hours in quarter q, and

nq=the number of hours in the quarter with

valid 5-minute hourly SO2 maximums

q=the index for each quarter, q=1, 2, 3 or 4.

2. The expected number of exceedances for

the quarter must be rounded to the nearest

hundredth (fractional values equal to or

greater than 0.005 are rounded up).

d.1. The expected number of exceedances

for the year, e, is the sum of the estimates for

each quarter.

e eq

q

=

=

∑

1

4

2. The expected number of

exceedances for a single year must be

rounded to one decimal place (fractional

values equal to or greater than 0.05 are

rounded up).

e. The number of exceedances is then

estimated by averaging the individual

annual estimates over a 2-year period,

rounding to the nearest integer, and

comparing with the allowable

exceedance rate of one per year

(fractional values equal to or greater

than 0.5 are rounded up; e.g., an

expected number of exceedances of 1.5

would be rounded to 2, which is the

lowest value for violating the trigger

level.

f. Example.

1. During the most recent quarter,

1210 out of a possible 2208 5-minute

hourly maximums were recorded, with

one observed exceedance of the 5-

minute trigger level. Using formula [1],

the expected number of exceedances for

the quarter is:

eq = 1 x 2208/1210 = 1.825 or 1.83

2. If the expected exceedances for the

other 4 quarters were 0.0, then using

formula [2], the expected number of

exceedances for the year is:

1.83 + 0.0 + 0.0 + 0.0 = 1.83 or 1.8

3. If the expected number of

exceedances for the previous year was

0.0, then the expected number of

exceedances is estimated by:

(1.8 + 0.0)/2 = 0.9 or 1

4. Since 1 is not greater than the

allowable number of exceedances, this

monitoring site would not violate the

trigger level.

PART 58—AMBIENT AIR QUALITY

SURVEILLANCE

1. The authority citation for part 58

continues to read as follows:

Authority: Secs 110, 301(a), and 319 of the

Clean Air Act as amended, (42 U.S.C. 7410,

7601(a), and 7619).

2. Section 58.1 is amended by adding

and reserving paragraphs (aa) through

(hh) and by adding paragraphs (ii) and

(jj) to read as follows:

§ 58.1 Definitions.

* * * * *

(ii) ‘‘Metropolitan Statistical Area’’

means the most recent area as

designated by the U.S. Office of

Management and Budget and

population figures from the U.S. Bureau

of the Census. The Department of

Commerce defines a metropolitan area

as ‘‘one of a large population nucleus,

together with adjacent communities

which have a high degree of economic

and social integration with that

nucleus.’’ 1

(jj) ‘‘Consolidated Metropolitan

Statistical Area’’ means the most recent

area as designated by the U.S. Office of

Management and Budget and

population figures from the Bureau of
12516 Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules

2See footnote 1 in paragraph (ii) of this section.

the Census. The Department of

Commerce provides ‘‘that within

metropolitan complexes of 1 million or

more population, separate component

areas are defined if specified criteria are

met. Such areas are designated primary

metropolitan statistical areas (PMSA’s);

and any area containing PMSA’s is

designated a consolidated metropolitan

statistical area (CMSA).’’ 2

* * * * *

3. In appendix C to part 58, section

2.4 is added to read as follows:

Appendix C—Ambient Air Quality

Monitoring Methodology

* * * * *

2.4 A monitoring method for SO2 used for

obtaining 5-minute average concentrations in

connection with targeted monitoring of an

SO2 source likely to produce short-duration,

high-level concentration peaks must be a

designated reference or equivalent method as

defined in § 50.1 of this chapter and must

meet the supplemental specifications for 5-

minute monitoring given in table B–1 of part

53 of this chapter.

* * * * *

4. In appendix D to part 58, section 1,

the last two sentences of the third

paragraph are removed, and replaced by

four new sentences to read as follows:

Appendix D—Network Design for State

and Local Air

Monitoring Stations (SLAMS), National

Air Monitoring Stations (NAMS), and

Photochemical Assessment Monitoring

Stations (PAMS)

* * * * *

1. * * *

* * * It should be noted that this

appendix contains no criteria for determining

the total number of stations in SLAMS

networks. A minimum number of lead

SLAMS is prescribed as well as a minimum

required number of SO2 SLAMS for those

counties not within the boundaries of any

CMSA/MSA. Also, a minimum required

number of SO2 SLAMS is listed for targeted

sources of SO2 emissions. The optimum size

of a particular SLAMS network involves

trade-offs among data needs and available

resources which EPA believes can best be

resolved during the annual network design

review process.

* * * * *

§ 2.3 [Amended]

5. In appendix D, the first paragraph

of section 2.3 is revised, and a new

paragraph is added between the first

and second paragraphs to read as

follows:

* * * * *

2. * * *

2.3 * * *

The spatial scales for SO2 SLAMS

monitoring are the micro, middle,

neighborhood, urban, and regional scales.

The most important spatial scales to

effectively characterize the emissions of SO2

from stationary sources are the micro,

middle, and neighborhood scales. Because of

the nature of SO2 emissions and the nature

of distributions over metropolitan areas, the

neighborhood scale is the most likely scale to

be represented by a single measurement in

the metropolitan area where the

concentration gradients are less steep, but

only if the undue effects from local sources

(minor or major point sources) can be

eliminated. Urban scales would represent

areas where the concentrations are uniform

over a larger geographical area. Regional

scale measurements would be associated

with rural areas and urban background

measurements.

Microscale—Emissions from stationary

sources may, under certain plume

conditions, result in high 5-minute and 24-

hour ground level concentrations at the

microscale level. The microscale

measurements would represent an area

impacted by the plume with dimensions

extending up to approximately 100 meters.

* * * * *

6. In appendix D, section 2.3, a

sentence is added to the end of the

paragraph titled ‘‘Middle Scale’’ to read

as follows:

* * * * *

2.3 * * *

Middle Scale * * * Emissions from

stationary sources that cover larger

geographic areas may also result in high 5-

minute and 24-hour SO2 concentrations.

* * * * *

7. In appendix D, section 2.3, a

sentence is added to the last paragraph

to read as follows:

* * * * *

2.3 * * *

* * * The use of SO2 saturation monitors

is encouraged to determine the areas of

maximum concentration from sources of SO2

emissions as an aid to locating reference or

equivalent SO2 monitors.

* * * * *

8. In appendix D, § 2.3, seven new

paragraphs are added at the end of this

section to read as follows:

* * * * *

The required number of sites needed to

measure SO2 concentrations for population

exposure in the metropolitan areas of the

counties are discussed in section 3.2 of this

appendix. However, there may be significant

point source emissions in other counties

which are not within the geographic

boundaries of any CMSA/MSA. To determine

the SO2 concentrations and exposures for

these counties, a minimum number of

SLAMS SO2 monitors will be required. Table

2 shows the minimum required number of

SLAMS SO2 monitors for those counties

which are not a part of any CMSA/MSA and

also have SO2 emissions greater than 20,000

tons/year as defined in the Air Facility

Subsystem of AIRS.

TABLE 2—STATE AND LOCAL AIR MONITORING STATIONS CRITERIA

Area SO2 emissions (tons/year) Minimum number

of SO2 stations

Counties (or parts of counties) not included in any CMSA/MSA .................................................. >100,000

20,000–100,000

<20,000

2

1

0

Monitors located to meet this requirement

would generally be either middle or

neighborhood scale of representativeness to

measure population exposure. The monitors

are not necessarily required to be located in

the county where the SO2 emissions

originate, but should be located in the

maximum concentration area. The maximum

concentration area may be determined by

modeling the SO2 emission sources and/or in

combination with SO2 saturation monitoring

studies.

The EPA will consider a request to waive

all or part of these requirements for these

areas. If monitoring has been conducted for

a minimum of 2 years and the measured

concentrations were low, then EPA will

consider a request to waive all or part of the

monitoring requirement in accordance with

EPA guidelines.

In addition to the above requirement for

SO2 monitors, SLAMS monitors are required

to be deployed around targeted sources of

SO2 emissions in order to produce 5-minute,

3-hour, 24-hour, and annual average

concentration measurements. A listing of

which sources are to be monitored, the

schedule for monitoring, and the rationale for

selecting the sources shall be prepared by the

State in a targeted SO2 monitoring plan to be

reviewed as part of the annual SLAMS

network review. The implementation of this

plan will be as expeditious as practicable.

To adequately monitor and characterize air

quality around point sources of SO2

emissions would require multiple point

monitors or open path analyzers (or a

combination of both). Financial and practical
Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules 12517

constraints may prohibit the deployment of

large numbers of SO2 monitors around these

targeted sources. Therefore, a modest

network with a minimum requirement of four

SO2 monitors around each targeted source

will be used. If open path analyzers with

multiple paths are used, each monitoring

path could potentially be substituted for one

point SO2 monitor. Modeling and/or

saturation sampling may be used to

determine the general area(s) of expected

maximum SO2 concentrations based on the

most predominant wind direction. One

monitor will be located at the fence line

downwind of the most predominant wind

direction, and a second monitor will be

located in the modeled maximum

concentration area based on the most

predominant wind direction. Since wind

directions frequently change from one season

to another, the second most predominant

wind direction will be used to locate the

second pair of monitors. The third monitor

will be located at the fence line downwind

of the second most predominant wind

direction, and the fourth monitor will be

located in the modeled maximum

concentration area based on the second most

predominant wind direction. However, for

situations where there is complex terrain

and/or meteorology, additional monitors may

be required to adequately monitor the

emissions.

In some cases, it is simply not practical to

place monitors at the indicated modeled

locations of maximum concentrations. Some

examples may include locations over open

bodies of water, on rivers, swamps, cliffs, etc.

The EPA Regional Offices and the State or

local air pollution control agencies should

determine alternative locations and

alternative network designs on a case-by-case

basis.

The use of SO2 monitoring around targeted

sources of SO2 emissions is intended to

capture high 5-minute peak concentrations as

well as exceedances of the 3-hour, 24-hour,

and annual mean standards for SO2.

However, there will be cases where this

monitoring strategy will be implemented

around the targeted sources of SO2 emissions,

and the resulting measured SO2

concentrations will be low. Therefore, SO2

monitoring around a targeted source must be

conducted for a minimum of 2 years to

account for factors such as year-to-year

variability in meteorology, change of plant

processes, etc. If monitoring has been

conducted for a minimum of 2 years, and the

concentrations were low, then a decision

could be made in the annual SLAMS network

review between the EPA Regional Office and

the State or local air pollution control agency

to move the SO2 monitors to another targeted

source of SO2 emissions. In general, it is

more important to monitor around another

targeted source of SO2 emissions than to

retain monitors around a source with

demonstrated low SO2 concentrations.

9. In appendix D, the first two

sentences of the first paragraph of

section 3 are removed and the following

two sentences are added to read as

follows:

* * * * *

3. * * *

The NAMS must be stations selected from

the SLAMS network with emphasis given to

urban and multisource areas. Areas to be

monitored must be selected based on the

CMSA/MSA population and pollutant

emission concentration levels as defined in

the Air Facility Subsystem of AIRS. * * *

* * * * *

10. In appendix D, the first paragraph

in section 3.2 and Table 3 are revised to

read as follows:

* * * * *

3.2 Sulfur Dioxide (SO2) Design Criteria for

NAMS.

It is desirable to have several NAMS in the

more polluted and densely populated urban

and multisource areas to characterize the

national and regional SO2 air quality trends

and geographical patterns. Table 3 shows the

required number of NAMS monitors in the

metropolitan areas to accomplish this

purpose. These neighborhood scale

monitoring stations (which would be located

within the boundaries of the CMSA/MSA)

would normally be classified as category (a)

or (b) as discussed in section 3. The actual

number and location of the NAMS must be

determined by the EPA Regional Office and

the State agency, subject to the approval of

EPA Headquarters (OAR).

TABLE 3.—NATIONAL AIR MONITORING STATION CRITERIA

CMSA/MSA population SO2 emissions

(tons/year)

Minimum

required

number

SO2 stations

>1,000,000 ................................................................................................................................................................. 200,000 3

100,000–200,000 2

0–100,000 1

200,000–1,000,000 .................................................................................................................................................... >200,000 3

100,000–200,000 2

20,000–100,000 1

>20,000 0

50,000–200,000 ......................................................................................................................................................... >100,000 2

20,000–100,000 1

<20,000 0

* * * * *

11. In appendix D, section 5, Table 5 is amended by revising the entry for ‘‘Micro’’ to read as follows:

* * * * *

5. * * *

TABLE 5.—SUMMARY OF SPATIAL SCALES FOR SLAMS AND REQUIRED SCALES FOR NAMS

Spatial scale

Scale applicable for SLAMS Scales Required for NAMS

SO2 CO O3 NO2 Pb PM–

10 SO2 CO 03 NO2 Pb PM–10

Micro .................................................................................. ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔

* * * * * * *
12518 Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules

* * * * *

12. In appendix E to part 58, § 3.1, the

fourth sentence is revised to read as

follows:

Appendix E—Probe Siting Criteria for

Ambient Air Quality Monitoring

* * * * *

3. * * *

3.1 * * * Therefore, the probe or at least

80 percent of the monitoring path must be

located 2 to 15 meters above ground level for

all scales of measurements. * * *

* * * * *

13. In appendix F to part 58, by

revising §§ 2.1, 2.1.1, and 2.1.2 to read

as follows:

Appendix F—Annual SLAMS Air

Quality Information

* * * * *

2.1 Sulfur Dioxide (SO2).

2.1.1 Site and Monitoring Information.

City name (when applicable), county name

and street address of site location. AIRS site

code. AIRS monitoring method code. Number

of 5-minute hourly maximum observations.

Number of hourly observations.

2.1.2 Annual Summary Statistics. Annual

arithmetic mean (ppm). Highest and second

highest 24-hour averages (ppm) (block

averages measured midnight to midnight)

and dates of occurrence. Highest and second

highest 5-minute hourly maximums (ppm)

(block averages) and dates and times (hour)

of occurrence when 5-minute measurements

are required. Highest and second highest 3-

hour averages (ppm) (block averages

beginning at midnight) and dates and times

(ending hour) of occurrence. Number of

exceedances of the 24-hour primary NAAQS.

Number of exceedances of the 5-minute

primary NAAQS (if a 5-minute primary

NAAQS is promulgated) when 5-minute

measurements are required. Number of

exceedances of the 3-hour secondary

NAAQS.

* * * * *

14. Appendix G is amended by

revising tables 1 and 2 and Figure 3 to

read as follows:

Appendix G—Uniform Air Quality

Index and Daily Reporting

* * * * *

TABLE 1.—BREAKPOINTS FOR PSI IN METRIC UNITS 1

PSI value (Ψ) 24-hr. PM

μg/m3

24-hr. SO2

μg/m3

8-hr. CO

mg/m3

1-hr. 03

μg/m3

1-hr. NO2

μg/m3

50 ............................................................................................................. 50 3 80 5 120 (2)

100 ........................................................................................................... 150 3 365 10 235 (2)

200 ........................................................................................................... 350 3 500 17 400 1,130

300 ........................................................................................................... 420 3 600 34 800 2,260

400 ........................................................................................................... 500 3 675 46 1,000 3,000

500 ........................................................................................................... 600 3 750 57.5 1,200 3,750

1At 25°C and 760 mm Hg. 2 No index values reported at these concentration levels because there is no short-term NAAQS.

3All the concentration levels are used for illustrative purposes only. The actual levels will be determined at the time of the promulgation of the

standard.

TABLE 2.—BREAKPOINTS FOR PSI

[Parts per million]

PSI value (Ψ) 24-hr.

SO2

8-hr.

CO

1-hr.

03

1-hr.

NO2

50 ............................................................................................................................................................................. 2 0.03 4.5 .06 (1)

100 ........................................................................................................................................................................... 2 0.12 9 .12 (1)

200 ........................................................................................................................................................................... 2 0.19 15 0.2 0.6

300 ........................................................................................................................................................................... 2 0.23 30 0.4 1.2

400 ........................................................................................................................................................................... 2 0.26 40 0.5 1.6

500 ........................................................................................................................................................................... 2 0.29 50 0.6 2.0

1 No index value reported at these concentration levels because there is no short-term NAAQS.

2All the concentration levels are used for illustrative purposes only. The actual levels will be determined at the time of the promulgation of the

standard.

* * * * *

BILLING CODE 6560–50–P
Federal Register / Vol. 60, No. 44 / Tuesday, March 7, 1995 / Proposed Rules 12519

BILLING CODE 6560–50–C

* * * * *

[FR Doc. 95–5021 Filed 3–6–95; 8:45 am]

BILLING CODE 6560–50–P

40 CFR Part 52

[TX–17–1–5600b; FRL–5163–4]

Approval and Promulgation of

Implementation Plans; Texas State

Implementation Plan Revision;

Corrections for Reasonably Available

Control Technology (RACT) Rules;

Volatile Organic Compounds (VOC)

RACT Catch-Ups

AGENCY: Environmental Protection

Agency (EPA).

ACTION: Notice of proposed rulemaking.

SUMMARY: The EPA is approving

revisions to the Texas State

Implementation Plan (SIP) submitted by

the State of Texas on June 8, 1992, and

additional revisions which were

submitted on November 13, 1992. These

SIP revisions contain regulations which

require the implementation of RACT for

various types of VOC sources. These

revisions respond to the requirements of

section 182(b)(2) of the Federal Clean

Air Act, as amended in 1990 (CAA), for

States to adopt RACT rules by

November 15, 1992, for major VOC

sources which are not covered by an

existing EPA Control Techniques

Guideline (CTG) and for all sources

covered by an existing CTG. These

revisions also include corrections to the

monitoring, recordkeeping, and

reporting requirements for Victoria

County, in order to make the VOC rules

more enforceable in that County.

In the final rules section of this

Federal Register, the EPA is approving

these SIP revisions as a direct final

rulemaking without prior proposal

because the EPA views this action as

noncontroversial and anticipates no

adverse comments. A detailed rationale

for the approval is set forth in the direct

final rule. If no adverse or critical

comments are received in response to

that direct final rule, no further activity

is contemplated in relation to this

proposed rule. If the EPA receives

adverse or critical comments, the direct

final rule will be withdrawn and all

public comments received will be

addressed in a subsequent final rule

based on this proposed rule. The EPA

will not institute a second comment

period on this action. Any parties

interested in commenting on this action

should do so at this time.

DATES: Comments on this proposed rule

must be received in writing by April 6,

1995.

ADDRESSES: Comments should be

mailed to Guy R. Donaldson, Acting

Chief, Air Planning Section (6T-AP),

U.S. EPA Region 6, 1445 Ross Avenue,

Dallas, Texas 75202–2733. Copies of the

State’s petition and other information

relevant to this action are available for

inspection during normal hours at

following locations:

U.S. Environmental Protection Agency,

Region 6, Air Programs Branch (6T–

A), 1445 Ross Avenue, Suite 700,

Dallas, Texas 75202–2733.

Texas Natural Resource Conservation

Commission, Office of Air Quality,

12124 Park 35 Circle, P.O. Box 13087,

Austin, Texas 78711–3087.

Anyone wishing to review this

petition at the EPA office is asked to

contact the person below to schedule an

appointment 24 hours in advance.

FOR FURTHER INFORMATION CONTACT: Mr.

Mick Cote, Planning Section (6T–AP),

EPA Region 6, telephone (214) 665–

7219.

SUPPLEMENTARY INFORMATION: See the

information provided in the direct final