[Federal Register Volume 72, Number 45 (Thursday, March 8, 2007)]
[Proposed Rules]
[Pages 10445-10453]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-3897]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 51 and 52

[EPA-HQ-OAR-2001-0004; FRL-8284-1]
RIN 2060-AN88


Prevention of Significant Deterioration (PSD) and Nonattainment 
New Source Review (NSR): Reasonable Possibility in Recordkeeping

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The EPA proposes revisions to the regulations governing the 
major new source review (NSR) programs mandated by parts C and D of 
title I of the Clean Air Act (CAA). These proposed changes clarify the 
``reasonable possibility'' recordkeeping and reporting standard of the 
2002 NSR reform rules. The ``reasonable possibility'' standard 
identifies for sources and reviewing authorities the circumstances 
under which a major stationary source undergoing a modification that 
does not trigger major NSR must keep records. The standard also 
specifies the recordkeeping and reporting requirements on such sources. 
Recently, the U.S. Court of Appeals for the DC Circuit in New York v. 
EPA, 413 F.3d 3 (DC Cir. 2005) (New York) remanded for the EPA either 
to provide an acceptable explanation for its ``reasonable possibility'' 
standard or to devise an appropriately supported alternative. To 
satisfy the Court's remand, we (the EPA) are proposing two alternative 
options to clarify what constitutes ``reasonable possibility'' and when 
the ``reasonable possibility'' recordkeeping requirements apply. The 
two options are the ``percentage increase trigger'' and the ``potential 
emissions trigger.''

DATES: Comments. Comments must be received on or before May 7, 2007.
    Public Hearing. If anyone contacts EPA requesting a public hearing 
by March 22, 2007, we will hold a public hearing approximately 30 days 
after publication in the Federal Register.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2001-0004 by one of the following methods:
    <bullet> http://www.regulations.gov: Follow the online instructions 
for submitting comments.
    <bullet> E-mail: <a href="/cdn-cgi/l/email-protection#62034f030c064f104f060d01090716220712034c050d14"><span class="__cf_email__" data-cfemail="40216d212e246d326d242f232b2534002530216e272f36">[email protected]</span></a>.
    <bullet> Fax: (202) 566-1741.
    <bullet> Mail: Air and Radiation Docket and Information Center, 
Environmental Protection Agency, Mailcode: 6102T, 1200 Pennsylvania 
Ave., NW., Washington, DC 20460. In addition, please mail a copy of 
your comments on the information collection provisions to the Office of 
Information and Regulatory Affairs, Office of Management and Budget 
(OMB), Attn: Desk Officer for EPA, 725 17th St., NW., Washington, DC 
20503.
    <bullet> Hand Delivery: Environmental Protection Agency, EPA West 
Building, Room 3334, 1301 Constitution Ave., NW., Washington, DC. Such 
deliveries are only accepted during the Docket's normal hours of 
operation, and special arrangements should be made for deliveries of 
boxed information.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2001-0004. EPA's policy is that all comments received will be included 
in the public docket without change and may be made available online at 
http://www.regulations.gov, including any personal information 
provided, unless the comment includes information claimed to be 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Do not submit information that you 
consider to be CBI or otherwise protected through http://www.regulations.gov or e-mail. The http://www.regulations.gov Web site 
is an ``anonymous access'' system, which means EPA will not know your 
identity or contact information unless you provide it in the body of 
your comment. If you send an e-mail comment directly to EPA without 
going through http://www.regulations.gov, your e-mail address will be 
automatically captured and included as part of the comment that is 
placed in the public docket and made available on the Internet. If you 
submit an electronic comment, EPA recommends that you include your name 
and other contact information in the body of your comment and with any 
disk or CD-ROM you submit. If EPA cannot read your comment due to 
technical difficulties and cannot contact you for clarification, EPA 
may not be able to consider your comment. Electronic files should avoid 
the use of special characters, avoid any form of encryption, and be 
free of any defects or viruses. For additional information about EPA's 
public docket, visit the EPA Docket Center homepage at http://www.epa.gov/epahome/dockets.htm. For additional instructions on 
submitting comments, go to section I.B of the SUPPLEMENTARY INFORMATION 
section of this document.
    Docket: All documents in the docket are listed in the http://www.regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, is not placed on the Internet and will be 
publicly available only in hard copy form. Publicly available docket 
materials are available either electronically in http://www.regulations.gov or in hard copy at the Air and Radiation Docket and 
Information Center, EPA/DC, EPA West, Room 3334, 1301 Constitution 
Ave., NW., Washington, DC. The Public

[[Page 10446]]

Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through 
Friday, excluding legal holidays. The telephone number for the Public 
Reading Room is (202) 566-1744, and the telephone number for the Air 
and Radiation Docket and Information Center is (202) 566-1742.
    Public Hearing: If a public hearing is held, it will be held at 9 
a.m. in EPA's Auditorium in Research Triangle Park, North Carolina, or 
at an alternate site nearby. Details regarding the hearing (time, date, 
and location) will be posted on EPA's Web site at http://www.epa.gov/nsr not later than 15 days prior to the hearing date. People interested 
in presenting oral testimony or inquiring as to whether a hearing is to 
be held should contact Ms. Pam Long, Air Quality Planning Division, 
Office of Air Quality Planning and Standards (C504-03), U.S. 
Environmental Protection Agency, Research Triangle Park, NC 27711, 
telephone (919) 541-0641, fax number (919) 541-5509, e-mail address 
<a href="/cdn-cgi/l/email-protection#117d7e7f763f61707c517461703f767e67"><span class="__cf_email__" data-cfemail="305c5f5e571e40515d705540511e575f46">[email protected]</span></a>, at least 2 days in advance of the public hearing (see 
DATES. People interested in attending the public hearing must also call 
Ms. Long to verify the time, date, and location of the hearing. The 
public hearing will provide interested parties the opportunity to 
present data, views, or arguments concerning the proposed action.

FOR FURTHER INFORMATION CONTACT: Ms. Lisa Sutton, Air Quality Policy 
Division, Office of Air Quality Planning and Standards (C504-03), 
Environmental Protection Agency, Research Triangle Park, NC 27711; 
telephone number: (919) 541-3450; fax number: (919) 541-5509; e-mail 
address: <a href="/cdn-cgi/l/email-protection#2a595f5e5e4544044643594b6a4f5a4b044d455c"><span class="__cf_email__" data-cfemail="ccbfb9b8b8a3a2e2a0a5bfad8ca9bcade2aba3ba">[email protected]</span></a>.

SUPPLEMENTARY INFORMATION: 

I. General Information

A. Does This Action Apply To Me?

    Entities affected by this rule include sources in all industry 
groups. The majority of sources potentially affected are expected to be 
in the following groups:

------------------------------------------------------------------------
          Industry Group             SIC \a\           NAICS \b\
------------------------------------------------------------------------
Electric Services.................        491  221111, 221112, 221113,
                                                221119, 221121, 221122.
Petroleum Refining................        291  324110.
Industrial Inorganic Chemicals....        281  325181, 325120, 325131,
                                                325182, 211112, 325998,
                                                331311, 325188.
Industrial Organic Chemicals......        286  325110, 325132, 325192,
                                                325188, 325193, 325120,
                                                325199.
Miscellaneous Chemical Products...        289  325520, 325920, 325910,
                                                325182, 325510.
Natural Gas Liquids...............        132  211112.
Natural Gas Transport.............        492  486210, 221210.
Pulp and Paper Mills..............        261  322110, 322121, 322122,
                                                322130.
Paper Mills.......................        262  322121, 322122.
Automobile Manufacturing..........        371  336111, 336112, 336211,
                                                336992, 336322, 336312,
                                                336330, 336340, 336350,
                                                336399, 336212, 336213.
Pharmaceuticals...................        283  325411, 325412, 325413,
                                                325414.
------------------------------------------------------------------------
\a\ Standard Industrial Classification.
\b\ North American Industry Classification System.

    Entities affected by the rule also include States, local permitting 
authorities, and Indian tribes whose lands contain new and modified 
major stationary sources.

B. What Should I Consider as I Prepare My Comments for EPA?

    1. Submitting CBI. Do not submit this information to EPA through 
http://www.regulations.gov or e-mail. Clearly mark the part or all of 
the information that you claim to be CBI. For CBI information in a disk 
or CD-ROM that you mail to EPA, mark the outside of the disk or CD-ROM 
as CBI and then identify electronically within the disk or CD-ROM the 
specific information that is claimed as CBI. In addition to one 
complete version of the comment that includes information claimed as 
CBI, a copy of the comment that does not contain the information 
claimed as CBI must be submitted for inclusion in the public docket. 
Information so marked will not be disclosed except in accordance with 
procedures set forth in 40 CFR part 2.
    2. Tips for Preparing Your Comments. When submitting comments, 
remember to:
    <bullet> Identify the rulemaking by docket number and other 
identifying information (subject heading, Federal Register date, and 
page number).
    <bullet> Follow directions--The Agency may ask you to respond to 
specific questions or organize comments by referencing a Code of 
Federal Regulations (CFR) part or section number.
    <bullet> Explain why you agree or disagree, suggest alternatives, 
and provide substitute language for your requested changes.
    <bullet> Describe any assumptions and provide any technical 
information and/or data that you used.
    <bullet> If you estimate potential costs or burdens, explain how 
you arrived at your estimate in sufficient detail to allow for it to be 
reproduced.
    <bullet> Provide specific examples to illustrate your concerns, and 
suggest alternatives.
    <bullet> Explain your views as clearly as possible, avoiding the 
use of profanity or personal threats.
    <bullet> Make sure to submit your comments by the comment period 
deadline identified.
    Commenters wishing to submit proprietary information for 
consideration must clearly distinguish such information from other 
comments and clearly label it as CBI. Send submissions containing such 
proprietary information directly to the following address, and not to 
the public docket, to ensure that proprietary information is not 
inadvertently placed in the docket: Attention: Mr. Roberto Morales, 
U.S. Environmental Protection Agency, OAQPS Document Control Officer, 
109 TW Alexander Drive, Room C404-02, Research Triangle Park, NC 27711. 
EPA will disclose information identified as CBI only to the extent 
allowed by the procedures set forth in 40 CFR part 2. If no claim of 
confidentiality accompanies a submission when it is received by the 
EPA, the information may be made available to the public without 
further notice to the commenter.

C. Where Can I Obtain Additional Information?

    In addition to being available in the docket, an electronic copy of 
this proposed rule is also available on the World Wide Web. Following 
signature

[[Page 10447]]

by the EPA Administrator, a copy of this proposed rule will be posted 
on the EPA's New Source Review (NSR) Web site, under Regulations & 
Standards, at http://www.epa.gov/nsr.

D. How Is This Preamble Organized?

    The information presented in this preamble is organized as follows:

I. General Information
    A. Does This Action Apply To Me?
    B. What Should I Consider as I Prepare My Comments for EPA?
    C. Where Can I Obtain Additional Information?
    D. How Is This Preamble Organized?
II. Introduction
    A. Purpose of Proposed Rulemaking
    B. Background
    C. Reasonable Possibility Standard
    D. Court Remand of Reasonable Possibility Standard
    E. Interim Interpretation of Reasonable Possibility in Appendix 
S
III. Description of This Proposed Action
    A. Application of ``Reasonable Possibility'' Standard
    B. Options for Circumstances Under Which ``Reasonable 
Possibility'' Standard Applies
IV. Statutory and Executive Order Reviews
    A. Executive Order 12866--Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Analysis (RFA)
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132--Federalism
    F. Executive Order 13175--Consultation and Coordination with 
Indian Tribal Governments
    G. Executive Order 13045--Protection of Children from 
Environmental Health Risks and Safety Risks
    H. Executive Order 13211--Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898--Federal Actions to Address 
Environmental Justice in Minority Populations and Low-Income 
Populations
V. Statutory Authority

II. Introduction

A. Purpose of Proposed Rulemaking

    On December 31, 2002 (67 FR 80187), we promulgated final changes 
(variously, ``2002 NSR reform rules,'' ``NSR reform,'' or ``reform 
rules'') to the major NSR program contained in 40 CFR 51.165, 51.166, 
52.21, and 52.24. Major elements of these NSR reform changes concerned 
baseline emissions, actual-to-projected-actual methodology, Clean 
Units, Plantwide Applicability Limitations (PALs), and Pollution 
Control Projects (PCPs). At that time we also added ``reasonable 
possibility'' recordkeeping requirements, to apply to projects at 
existing emissions units at a major stationary source (other than 
projects at a Clean Unit or at a source with a PAL). Further, the 
``reasonable possibility'' requirements only apply if such a project 
relies on a projection of post-project actual emissions (as opposed to 
potential to emit) in order to demonstrate that the project is not part 
of a major modification.
    It was our intent to finalize changes to another part of the major 
NSR program, at 40 CFR part 51, appendix S (``Appendix S''), precisely 
as we finalized the NSR reform changes. Appendix S provides NSR 
requirements applicable to nonattainment areas after EPA promulgates a 
new or revised NAAQS but before the area has an approved NSR SIP. 
However, in the New York case, the Court remanded the ``reasonable 
possibility'' recordkeeping and reporting provision of the 2002 NSR 
reform rules for the EPA either to provide an acceptable explanation or 
to devise an appropriately supported alternative. The New York case 
also vacated the Clean Unit provision and the PCP exemption in the 2002 
NSR reform rules. In a separate Federal Register notice published on 
this date, we are finalizing changes to Appendix S to add the December 
2002 NSR reform changes. These final changes also include an interim 
interpretation of the ``reasonable possibility'' standard based on the 
``percentage increase trigger'' option as described later.
    To reflect that the Court vacated the Clean Unit provision, this 
proposed rule omits reference to Clean Units in the description of 
projects to which the ``reasonable possibility'' provisions apply.
    The purpose of this rulemaking is to address the Court's remand by 
clarifying the reasonable possibility standard and thus clarifying the 
circumstances under which records must be kept for projects that do not 
trigger major NSR. For purposes of 40 CFR 51.165, 51.166, 52.21, 52.24, 
and part 51 appendix S, we are proposing two main options for 
clarifying the ``reasonable possibility'' standard.

B. Background

1. 2002 NSR Reform Rule
    In our 2002 NSR reform rule, we revised the major NSR applicability 
test by promulgating an actual-to-projected-actual applicability test 
for projects involving existing emissions units. Under this test, 
sources base major NSR applicability determinations on projected actual 
emissions (not necessarily their future potential to emit).
    Until promulgation of the 2002 NSR reform rules, sources that were 
not electric utility steam generating units (EUSGUs) were subject to 
the ``potential to emit'' test for determining emissions increases and 
therefore were not required to keep records of projected emissions. The 
2002 NSR reform rules changed the applicability test for non-EUSGU 
sources and created certain recordkeeping requirements under what is 
referred to as the ``reasonable possibility'' standard. The NSR reform 
rules added the same ``reasonable possibility'' recordkeeping and 
reporting requirements for EUSGUs.
2. July 1992 Rule for EUSGUs
    Primarily as a result of Wisconsin Elec. Power Co. v. Reilly 
(``WEPCO''), 893 F.2d 901 (7th Cir. 1990), we revised our NSR 
regulations in 1992 to apply an actual-to-future-actual test on all 
physical or operational changes at EUSGUs except those that are an 
addition of a new unit or constitute a replacement of an existing unit. 
The 1992 regulation (57 FR 32314, July 21, 1992) provides a 
``representative actual annual emissions'' methodology that requires 
the EUSGU (other than a new unit or the replacement of an existing 
unit) to compare its baseline emissions with its estimated future 
actual emissions to determine how much the proposed change will 
increase actual emissions. A discussion of the WEPCO case is included 
in the preamble to the 1992 regulation.
    In the 1992 regulation, EPA added a reporting provision as a 
safeguard to ensure that future actual emissions resulting from the 
change that exceeded the estimate would not go unnoticed or unreviewed. 
Under the reporting provision, sources that utilize the 
``representative actual annual emissions'' methodology to determine 
that they are not subject to NSR must maintain and submit sufficient 
records to determine if the change results in an increase in 
representative actual annual emissions. The regulation generally 
required that the owner or operator submit records to the reviewing 
authority on an annual basis for a period of 5 years from the date the 
unit resumes regular operation after the change; however, it allowed 
for a longer tracking period, not to exceed 10 years, in cases where 
the permitting agency determined that such longer period was necessary 
to capture normal source operations. We expected that documentation of 
post-change actual annual emissions would not impose any additional 
data collection burden on the part of the EUSGUs, because the EUSGUs 
would submit the same data

[[Page 10448]]

normally used to report emissions or operational levels under other 
existing requirements. As we noted in the preamble to the 1992 
regulations (57 FR at 32325), the purpose of the provision is ``to 
provide a reasonable means of determining whether a significant 
increase in representative actual annual emissions resulting from a 
proposed change at an existing utility occurs within the 5 years 
following the change.'' Prior to 1992, no sources were required to keep 
records of projected emissions under major NSR because only the actual-
to-potentials test was used.

C. Reasonable Possibility Standard

    Under the two-step applicability test of the 2002 NSR reform rules, 
a physical or operational change is a major modification for a 
regulated NSR pollutant if it causes both: (1) A significant emissions 
increase (see, e.g., 40 CFR 52.21(b)(40)); and (2) a significant net 
emissions increase (as defined pursuant to, e.g., 40 CFR 52.21(b)(3) 
and (b)(23)). Under the first step of this test, you compare baseline 
actual emissions before the change to projected actual emissions after 
the change to determine whether the change would result in a 
significant increase in emissions. The regulation defines ``projected 
actual emissions'' such that the owner or operator of the major 
stationary source projects the post-project maximum annual rate at 
which an existing emissions unit would emit a regulated NSR pollutant. 
See, e.g., 40 CFR 52.21(b)(41)(i). This definition provides that an 
owner or operator may use the emissions unit's potential to emit, in 
tons per year, in lieu of a projection. Under the second step, which is 
referred to as netting, you net the contemporaneous emissions decreases 
and increases that occurred at the source against the emissions 
increase determined under the first step. If the net amount equals or 
exceeds the significant level, then the change triggers major NSR. 
(``Significant levels'' for regulated NSR pollutants are commonly 
called ``significance levels'' or ``significance thresholds,'' and 
these terms are used interchangeably for purposes of this proposed 
action.)
    In the reform rules (see 40 CFR 51.165(a)(6), 40 CFR 51.166(r), and 
40 CFR 52.21(r)), EPA determined that a source making a change need not 
keep records of its emissions (including data on which the source based 
its projections and data of actual emissions going forward) unless the 
source believes there is a ``reasonable possibility'' that the change 
may result in a significant emissions increase. See, e.g., 40 CFR 
52.21(r)(6).

    The provisions of this paragraph (r)(6) apply to projects at an 
existing emissions unit at a major stationary source (other than 
projects at * * * a source with a PAL) in circumstances where there 
is a reasonable possibility that a project that is not a part of a 
major modification may result in a significant emissions increase 
and the owner or operator elects to use the method specified in 
paragraphs (b)(41)(ii)(a) through (c) of this section for 
calculating projected actual emissions.

    To determine whether a change at an existing emissions unit will 
result in an emissions increase, you must use an actual-to-projected-
actual applicability test. Note, however, that you may opt to use the 
source(s potential to emit as its projected actual emissions (see, 
e.g., 40 CFR 52.21(b)(41)(ii)(d)).
    The ``reasonable possibility'' standard requires that a source keep 
records if it meets the following three requirements: (i) The source 
projects post-change actual emissions and does not use the actual-to-
potential test. (ii) The source determines that the change would not 
trigger major NSR. (iii) The source nevertheless believes that there is 
a reasonable possibility that the change may significantly increase 
emissions.\1\ For subject sources, the ``reasonable possibility'' 
recordkeeping requirements apply to all regulated NSR pollutants, and 
they apply to each emissions unit that could be affected by the 
project. Further, if the project increases design capacity or PTE of 
any regulated NSR pollutant, the recordkeeping and reporting 
requirements apply for 10 years instead of 5 years. (For purposes of 
this proposed action, we refer to the physical or operational change 
as, interchangeably, a change or a project.)
---------------------------------------------------------------------------

    \1\ The ``reasonable possibility'' standard covers both EUSGUs 
and non-EUSGUs. As noted above, prior to promulgation of the 
``reasonable possibility'' standard, an EUSGU that made a change 
that did not result in a significant emissions increase (under the 
actual-to-projected-actual measure) was required to provide the 
permitting authority with at least 5 years of data to confirm the 
accuracy of the projection.
---------------------------------------------------------------------------

    More specifically, if your change or project has a reasonable 
possibility of resulting in a significant emissions increase, then you 
must: (1) Keep certain records that are created before construction 
(description of the project, identification of emissions units affected 
by the project, and a description of the applicability test); and (2) 
monitor emissions, calculate annual emissions, and maintain records of 
emissions for 5 years (or 10 years in certain cases) once the change is 
completed. If the change's annual emissions for a calendar year exceed 
the baseline by a significant amount and also differ from the 
projection, then you are additionally required to report emissions for 
the calendar year.

D. Court Remand of Reasonable Possibility Standard

    In the New York case, the Court held, ``Because EPA has failed to 
explain how it can ensure NSR compliance without the relevant data, we 
will remand for it either to provide an acceptable explanation for its 
`reasonable possibility' standard or to devise an appropriately 
supported alternative.'' 413 F.3d at 35-36. The Court explained:

    The problem is that EPA has failed to explain how, absent 
recordkeeping, it will be able to determine whether sources have 
accurately concluded that they have no `reasonable possibility' of 
significantly increased emissions. We recognize that less burdensome 
requirements may well be appropriate for sources with little 
likelihood of triggering NSR, but EPA needs to explain how its 
recordkeeping and reporting requirements allow it to identify such 
sources.

413 F.3d at 34. The Court added:

    [T]he intricacies of the actual-to-projected-actual methodology 
will aggravate the enforcement difficulties stemming from the 
absence of data. The methodology mandates that projections include 
fugitive emissions, malfunctions, and start-up costs, and exclude 
demand growth unrelated to the change. * * *. Each such 
determination requires sources to predict uncertain future events. 
By understating projections for emissions associated with 
malfunctions, for example, or overstating the demand growth 
exclusion, sources could conclude that a significant emissions 
increase was not reasonably possible. Without paper trails, however, 
enforcement authorities have no means of discovering whether the 
exercise of such judgment was indeed ``reasonable.''

Id. at 35.

    We are proposing options for determining the circumstances under 
which a change would have a reasonable possibility of significantly 
increasing emissions. With the final rulemaking, we intend to clarify 
the meaning of the ``reasonable possibility'' standard through the 
selected option(s) and thus fully address the Court's remand.

E. Interim Interpretation of Reasonable Possibility in Appendix S

    As stated earlier, in a separate Federal Register notice published 
on this date, we are establishing an interim interpretation of the 
reasonable possibility provisions for purposes of implementing appendix 
S. In that rulemaking, EPA is revising the major NSR requirements that 
are applicable to major sources in a State after EPA

[[Page 10449]]

revises a NAAQS but before the State receives EPA approval of its NSR 
SIP. The purpose of these revisions is to reflect the requirements of 
the 2002 NSR reform rule, taking into account the decision in New York.
    For purposes of Appendix S, we are providing an interim 
interpretation of ``reasonable possibility'' to apply during the period 
until we promulgate our clarification of the ``reasonable possibility'' 
standard. Under the interim interpretation, we conclude that there is a 
``reasonable possibility'' that the change would result in a 
significant emissions increase if the change's projected actual 
emissions increase equals or exceeds 50 percent of the applicable NSR 
significance level for any pollutant. We base this conclusion on an 
assumption that the magnitude of projected actual emissions correlates 
positively to the likelihood of a significant emissions increase. This 
test may be termed the ``percentage increase trigger'' that we propose 
in this action, as described below.

III. Description of This Proposed Action

    This action responds to the Court's remand by proposing two options 
for determining the circumstances under which a change or project must 
be considered to have a ``reasonable possibility'' of significantly 
increasing emissions. We explain our basis for why each option is 
enforceable and solicit input from the public.
    In this section, we also solicit comment on how the ``reasonable 
possibility'' standard is generally applied and what is to be recorded 
and reported in the case of a change or project for which there is a 
reasonable possibility that the change will result in a significant 
emissions increase.

A. Application of ``Reasonable Possibility'' Standard

    This proposed action makes clear that the requirements of the 
``reasonable possibility'' standard are triggered on a pollutant-
specific basis and apply on a project-wide basis. This approach is 
consistent with our 2002 NSR reform rules. In 40 CFR 52.21(r)(6)(iii), 
for example, we require the owner or operator to monitor ``emissions of 
any regulated NSR pollutant that could increase as a result of the 
project'' for which there is a reasonable possibility of a significant 
emissions increase.
    Note that the ``reasonable possibility'' standard is specific to 
projects at a major stationary source (see, e.g., 40 CFR 52.21(r)(6)). 
Therefore, the proposal to clarify this standard does not apply to 
existing minor sources. As a result, existing minor sources will not 
become subject to the ``reasonable possibility'' recordkeeping and 
reporting standard, even when they make changes that would, if they 
were major sources, trigger the applicability of those requirements. 
Minor sources remain subject to appropriate recordkeeping and reporting 
requirements in the State's minor NSR program.
    Note further that ``synthetic minor modifications'' are also not 
subject to the ``reasonable possibility'' standard. When a major 
stationary source undertakes a project that would be a major 
modification (as defined at 40 CFR 52.21(b)(2) and elsewhere) except 
that the source accepts a practically enforceable restriction in order 
to limit the project's increase in emissions to less than significant 
emissions increase level, the project is termed a ``synthetic minor 
modification.'' Such a source must keep records as part of the 
practically enforceable restriction (e.g., under a State's minor source 
NSR program) in order to demonstrate that the increase in potential 
emissions resulting from the project remains below the significance 
levels. However, these ``synthetic minor modifications'' are not 
subject to the ``reasonable possibility'' standard.
    When we finalize this action to clarify the ``reasonable 
possibility'' standard, we intend to apply the clarification where we 
refer to ``reasonable possibility'' in 40 CFR 51.165(a)(6), 
51.166(r)(6), 52.21(r)(6), and part 51 appendix S. Our final rule will 
supersede the interim interpretation of ``reasonable possibility'' that 
we are establishing for appendix S in a separate Federal Register 
notice published on this date.

B. Options for Circumstances Under Which ``Reasonable Possibility'' 
Standard Applies

    We propose the following two options for identifying the 
circumstances under which the increase in emissions caused by a project 
triggers the ``reasonable possibility'' recordkeeping and reporting 
requirements. Our preferred option is the ``percentage increase 
trigger,'' and as an alternative we propose the ``potential emissions 
trigger.'' The amendatory rule language included in this proposed rule 
is specific to the ``percentage increase trigger'' option. We believe 
the ``potential emissions trigger'' option would be effective without 
need for amendatory rule language.
1. Percentage Increase Trigger
    As our preferred option, we propose what we refer to as the 
``percentage increase trigger'' option for applying the ``reasonable 
possibility'' standard. This ``percentage increase trigger'' is also 
our interim interpretation for Appendix S purposes, as described 
earlier. Under this proposed option, you would conclude there is a 
reasonable possibility that your change will result in a significant 
emissions increase if the change's projected actual emissions increase 
equals or exceeds a percentage of the applicable NSR significance level 
for any pollutant. We propose to use 50 percent of the significance 
level for the relevant regulated NSR pollutant as the trigger, but we 
solicit comment on use of a different percentage to trigger 
recordkeeping and reporting, such as 25, 33, 66 or 75 percent. The 
significance levels for regulated NSR pollutants are provided in 40 CFR 
51.165(a)(1)(x), 51.166(b)(23)(i), 52.21(b)(23)(i), and paragraph 
II.A.10 in appendix S to part 51.
    As noted earlier, the Court found that EPA had not explained how, 
under the ``reasonable possibility'' methodology, EPA can ensure NSR 
compliance without a source's maintaining relevant data. The Court 
explained that for each major NSR applicability determination, the 
methodology requires sources to:

    * * * predict uncertain future events. By understating 
projections for emissions associated with malfunctions, for example, 
or overstating the demand growth exclusion, sources could conclude 
that a significant emissions increase was not reasonably possible. 
Without paper trails, however, enforcement authorities have no means 
of discovering whether the exercise of such judgment was indeed 
``reasonable.''

413 F.3d at 35.

    We believe that the proposed ``percentage increase trigger'' option 
addresses these concerns. The Court observed, ``We recognize that less 
burdensome requirements may well be appropriate for sources with little 
likelihood of triggering NSR, but EPA needs to explain how its 
recordkeeping and reporting requirements allow it to identify such 
sources.'' Id. at 34. The ``reasonable possibility'' requirements apply 
only in the case of a change that the source considers small, in that 
the source believes it increases projected emissions by only a small 
amount. That is, the requirements apply only with respect to a change 
that may result in a ``significant emissions increase.''
    The significance levels for most regulated NSR pollutants are on 
their face small. Thus, the projects associated with these amounts are 
relatively small. This is particularly so because under the 
``reasonable possibility'' standard, the requirements are triggered 
only by projects that may result in the specified levels of increased 
emissions, without

[[Page 10450]]

taking into account netting. For the same reasons, very large sources 
are less likely to make changes that are covered by the ``reasonable 
possibility'' standard because virtually any change that a very large 
source makes may be expected to increase emissions above the 
significance levels and require a major NSR permit.
    Moreover, under our proposal, a project would avoid triggering the 
``reasonable possibility'' requirements only if the source believed 
that the emissions increase from the project would be no more than 50 
percent of the significance levels. Therefore, our proposal 
considerably limits the number of projects that could avoid 
``reasonable possibility'' requirements. By assuming that the magnitude 
of projected actual emissions correlates positively to the likelihood 
of a significant emissions increase, this ``percentage increase 
trigger'' option provides that you keep records for projects with a 
reasonable possibility of significant emissions increases but also 
takes into account the impracticality of your having to keep records 
when anticipating only a small increase in emissions. Thus, EPA 
believes this interpretation addresses the issues identified by the 
Court in the New York case, in that we are providing a clear 
distinction, prior to construction, between projects more and less 
likely to trigger NSR. Table 1 illustrates by example how the 
``percentage increase trigger'' option would apply to two hypothetical 
projects at a major stationary source.

      Table 1.--Example Application of Percentage Increase Trigger
------------------------------------------------------------------------
                                 Project 1 example--  Project 2 example--
                                 smaller increase in  larger increase in
                                   actual emissions    actual emissions
 
------------------------------------------------------------------------
Example pollutant's NSR                            40.
 significance level (tpy).
Trigger level, based on 50                         20.
 percent of significance level
 (tpy).
                                ----------------------------------------
Baseline actual emissions (tpy)  50.................  50.
Projected actual emissions       60.................  90.
 after change (tpy).
Increase in actual emissions     10.................  40.
 (tpy).
Does project trigger             No, because          Yes, because
 ``reasonable possibility''       ``increase in        ``increase in
 requirements?                    actual emissions''   actual
                                  (10 tpy) is less     emissions'' (40
                                  than ``trigger       tpy) is greater
                                  level'' (20 tpy).    than ``trigger
                                                       level'' (20 tpy).
------------------------------------------------------------------------

    Under the ``percentage increase trigger'' option, we acknowledge 
that a source with projected actual emissions below 50 percent (or some 
other percentage) of the NSR significance levels would be able to avoid 
``reasonable possibility'' recordkeeping and reporting requirements. 
However, we believe that EPA has numerous means of enforcing the NSR 
provisions against such a source, even in the absence of records kept 
under the ``reasonable possibility'' standard. Two types of records a 
source owner or operator is generally expected to keep are: (1) Records 
to report emissions; and (2) records for business purposes. Records for 
business purposes could include corporate minutes, blueprints, plant 
manager logs, records of capital costs and purchases of materials, and 
other documents that would describe the types of changes made at the 
source (wholly apart from changes in emissions that result from the 
changes). Businesses also have incentives to maintain design parameter 
information for safety and maintenance reasons. We note that these 
records give EPA an adequate basis to bring to bear certain enforcement 
tools, such as the authority to compel document production, conduct 
inspections, and compel oral testimony, in order to enforce the 
``reasonable possibility'' standard. We solicit comment on the types of 
records sources keep for business purposes.
    We request comment on whether to adopt a percentage increase 
trigger for recordkeeping requirements under the ``reasonable 
possibility'' standard.
2. Potential Emissions Trigger
    We propose an alternative interpretation, what we refer to as the 
``potential emissions trigger'' option. Under this option, you would 
conclude there is a reasonable possibility that your change will result 
in a significant emissions increase if the post-change potential to 
emit equals or exceeds NSR significance levels (even though the source 
opts to base its determination as to whether NSR applies on projected 
actual emissions).
    The EPA believes the ``potential emissions trigger'' approach would 
also resolve the issues identified by the Court in the New York case. 
The Court raised the concern that the ``reasonable possibility'' 
methodology, as it currently stands, fails to explain how EPA can 
ensure NSR compliance without the source's maintaining relevant data. 
We explain below that potential emissions represent the upper bound of 
post-change emissions, and so under the ``potential emissions 
trigger,'' records of projected actual emissions are unnecessary for 
the purpose of ascertaining whether post-change emissions increased 
beyond expectations. As long as a project's post-change potential 
emissions are at or above significance levels, then the source will 
either trigger major NSR or will be subject to recordkeeping and 
reporting requirements under the ``potential emissions trigger.'' If 
the project's post-change potential emissions are below significance 
levels, then clearly the project's projected actual emissions would 
also necessarily be below significance levels, and the ``reasonable 
possibility'' standard would not apply. Thus, short of requiring 
recordkeeping and reporting for all projects that do not trigger major 
NSR, the ``potential emissions trigger'' requires recordkeeping and 
reporting of the greatest number of projects under the ``reasonable 
possibility'' standard.

IV. Statutory and Executive Order Reviews

A. Executive Order 12866--Regulatory Planning and Review

    Under Executive Order (EO) 12866 (58 FR 51735, October 4, 1993), 
this action is a significant regulatory action. The action was 
determined to be a ``significant regulatory action'' because it raises 
policy issues arising from the President's priorities. Accordingly, EPA 
submitted this action to the Office of Management and Budget (OMB) for 
review under EO 12866 and any changes made in response to OMB 
recommendations have been

[[Page 10451]]

documented in the docket for this action.

B. Paperwork Reduction Act

    This action does not impose any new information collection burden. 
We are not promulgating any new paperwork requirements (e.g., 
monitoring, reporting, recordkeeping) as part of this proposed action. 
However, the Office of Management and Budget (OMB) has previously 
approved the information collection requirements contained in the 
existing regulations (40 CFR parts 51 and 52) under the provisions of 
the Paperwork Reduction Act, 44 U.S.C. 3501 et seq., and has assigned 
OMB control number 2060-0003, EPA ICR number 1230.17. A copy of the OMB 
approved Information Collection Request (ICR) EPA ICR number 1230.17 
may be obtained from Susan Auby, Collection Strategies Division; U.S. 
Environmental Protection Agency (2822T); 1200 Pennsylvania Avenue, NW., 
Washington, DC 20460 or by calling (202) 566-1672.
    Burden means the total time, effort, or financial resources 
expended by persons to generate, maintain, retain, or disclose or 
provide information to or for a Federal agency. This includes the time 
needed to review instructions; develop, acquire, install, and utilize 
technology and systems for the purposes of collecting, validating, and 
verifying information, processing and maintaining information, and 
disclosing and providing information; adjust the existing ways to 
comply with any previously applicable instructions and requirements; 
train personnel to be able to respond to a collection of information; 
search data sources; complete and review the collection of information; 
and transmit or otherwise disclose the information.
    An agency may not conduct or sponsor, and a person is not required 
to respond to, a collection of information unless it displays a 
currently valid OMB control number. The OMB control numbers for EPA's 
regulations in 40 CFR are listed in 40 CFR part 9.

C. Regulatory Flexibility Analysis (RFA)

    The RFA generally requires an agency to prepare a regulatory 
flexibility analysis of any rule subject to notice and comment 
rulemaking requirements under the Administrative Procedure Act or any 
other statute unless the Agency certifies that the rule will not have a 
significant economic impact on a substantial number of small entities. 
Small entities include small businesses, small organizations, and small 
governmental jurisdictions.
    For purposes of assessing the impacts of this action on small 
entities, a small entity is defined as: (1) A small business as defined 
by the Small Business Administration's (SBA) regulations at 13 CFR 
121.201; (2) a small governmental jurisdiction that is a government of 
a city, county, town, school district, or special district with a 
population of less than 50,000; or (3) a small organization that is any 
not-for-profit enterprise that is independently owned and operated and 
is not dominant in its field.
    After considering the economic impacts of this proposed action on 
small entities, I certify that this action will not have a significant 
economic impact on a substantial number of small entities. This 
proposed rule will not impose any requirements on small entities. We 
continue to be interested in the potential impacts of the proposed rule 
on small entities and welcome comments on issues related to such 
impacts.

D. Unfunded Mandates Reform Act

    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public 
Law 104-4, establishes requirements for Federal agencies to assess the 
effects of their regulatory actions on State, local, and tribal 
governments and the private sector. Under section 202 of the UMRA, EPA 
generally must prepare a written statement, including a cost-benefit 
analysis, for proposed and final rules with ``Federal mandates'' that 
may result in expenditures to State, local, and Tribal governments, in 
the aggregate, or to the private sector, of $100 million or more in any 
1 year. Before promulgating an EPA rule for which a written statement 
is needed, section 205 of the UMRA generally requires EPA to identify 
and consider a reasonable number of regulatory alternatives and adopt 
the least costly, most cost-effective or least burdensome alternative 
that achieves the objectives of the rule. The provisions of section 205 
do not apply when they are inconsistent with applicable law. Moreover, 
section 205 allows EPA to adopt an alternative other than the least 
costly, most cost-effective or least burdensome alternative if the 
Administrator publishes with the final rule an explanation as to why 
that alternative was not adopted. Before EPA establishes any regulatory 
requirements that may significantly or uniquely affect small 
governments, including tribal governments, it must have developed under 
section 203 of the UMRA a small government agency plan.
    The plan must provide for notifying potentially affected small 
governments, enabling officials of affected small governments to have 
meaningful and timely input in the development of EPA regulatory 
proposals with significant Federal intergovernmental mandates, and 
informing, educating, and advising small governments on compliance with 
the regulatory requirements. This rule contains no Federal mandates 
(under the regulatory provisions of Title II of the UMRA) for State, 
local, or Tribal governments or the private sector.
    Thus, this rule is not subject to the requirements of sections 202 
and 205 of the UMRA.

E. Executive Order 13132--Federalism

    Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August 
10, 1999), requires EPA to develop an accountable process to ensure 
``meaningful and timely input by State and local officials in the 
development of regulatory policies that have federalism implications.'' 
``Policies that have federalism implications'' is defined in the 
Executive Order to include regulations that have ``substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government.''
    This proposal rule does not have federalism implications. It will 
not have substantial direct effects on the States, on the relationship 
between the national government and the States, or on the distribution 
of power and responsibilities among the various levels of government, 
as specified in Executive Order 13175. Thus, Executive Order 13175 does 
not apply to this action.
    In the spirit of Executive Order 13132, and consistent with EPA 
policy to promote communications between EPA and State and local 
governments, EPA is soliciting comment on this proposal from State and 
local officials.

F. Executive Order 13175--Consultation and Coordination With Indian 
Tribal Governments

    Executive Order 13175, entitled (Consultation and Coordination with 
Indian Tribal Governments (65 FR 13175, November 9, 2000), requires EPA 
to develop an accountable process to ensure ``meaningful and timely 
input by tribal officials in the development of regulatory policies 
that have tribal implications.'' This proposed rule does not have 
tribal implications, as specified in Executive Order 13175. There are 
no tribal authorities currently issuing major NSR and title V permits. 
Thus, Executive Order 13175 does not apply to this rule.

[[Page 10452]]

    Although Executive Order 13175 does not apply to this proposed 
rule, EPA specifically solicits comment on this proposed rule from 
Tribal officials.

G. Executive Order 13045--Protection of Children From Environmental 
Health Risks and Safety Risks

    Executive Order 13045, entitled ``Protection of Children from 
Environmental Health Risks and Safety Risks'' (62 FR 19885, April 23, 
1997), applies to any rule that: (1) Is determined to be ``economically 
significant'' as defined under Executive Order 12866, and (2) concerns 
an environmental health or safety risk that EPA has reason to believe 
may have a disproportionate effect on children. If the regulatory 
action meets both criteria, the Agency must evaluate the environmental 
health or safety effects of the planned rule on children, and explain 
why the planned regulation is preferable to other potentially effective 
and reasonably feasible alternatives considered by the Agency.
    This proposed rule is not subject to the Executive Order because it 
is not economically significant as defined in Executive Order 12866, 
and because the Agency does not have reason to believe the 
environmental health or safety risks addressed by this action present a 
disproportionate risk to children. This proposed action does not 
establish an environmental standard intended to mitigate health or 
safety risks but rather provides explanation of an existing 
recordkeeping and reporting standard.

H. Executive Order 13211--Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use

    This action is not a ``significant energy action'' as defined in 
Executive Order 13211, ``Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use'' (66 FR 
28355, May 22, 2001) because it is not likely to have a significant 
adverse effect on the supply, distribution, or use of energy.

I. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (NTTAA), Public Law 104-113, section 12(d) (15 U.S.C. 272 
note), directs EPA to use voluntary consensus standards in its 
regulatory activities unless to do so would be inconsistent with 
applicable law or otherwise impractical.
    Voluntary consensus standards are technical standards (for example, 
materials specifications, test methods, sampling procedures, and 
business practices) that are developed or adopted by voluntary 
consensus standards bodies. The NTTAA directs EPA to provide Congress, 
through OMB, explanations when the Agency decides not to use available 
and applicable voluntary consensus standards.
    This action does not involve technical standards. Therefore, EPA 
did not consider the use of any voluntary consensus standards.

J. Executive Order 12898--Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations

    Executive Order 12898, entitled ``Federal Actions to Address 
Environmental Justice in Minority Populations and Low-Income 
Populations'' (59 FR 7629, February 16, 1994), establishes federal 
executive policy on environmental justice. Its main provision directs 
federal agencies, to the greatest extent practicable and permitted by 
law, to make environmental justice part of their mission by identifying 
and addressing, as appropriate, disproportionately high and adverse 
human health or environmental effects of their programs, policies, and 
activities on minority populations and low-income populations in the 
United States.
    The EPA has determined that this proposed rule will not have 
disproportionately high and adverse human health or environmental 
effects on minority or low-income populations because it does not 
affect the level of protection provided to human health or the 
environment. This proposed rule provides explanation of an existing 
recordkeeping and reporting standard.

V. Statutory Authority

    The statutory authority for this action is provided by sections 
307(d)(7)(B), 101, 111, 114, 116, and 301 of the CAA as amended (42 
U.S.C. 7401, 7411, 7414, 7416, and 7601). This notice is also subject 
to section 307(d) of the CAA (42 U.S.C. 7407(d)).

List of Subjects

40 CFR Part 51

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Carbon monoxide, Intergovernmental relations, 
Lead, Nitrogen dioxide, Ozone, Particulate matter, Reporting and 
recordkeeping requirements, Sulfur oxides, Transportation, Volatile 
organic compounds.

40 CFR Part 52

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Carbon monoxide, Intergovernmental relations, 
Lead, Nitrogen dioxide, Ozone, Particulate matter, Reporting and 
recordkeeping requirements, Sulfur oxides, Transportation, Volatile 
organic compounds.

    Dated: February 28, 2007.
Stephen L. Johnson,
Administrator.
    For the reasons set out in the preamble, title 40, chapter I of the 
Code of Federal Regulations is proposed to be amended as set forth 
below.

PART 51--[AMENDED]

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

    Authority: 23 U.S.C. 101; 42 U.S.C. 7401-7671q.

Subpart I--[Amended]

    2. Section 51.165 is amended by revising paragraph (a)(6) 
introductory text and adding paragraph (a)(6)(vi) to read as follows:


Sec.  51.165  Permit requirements.

    (a) * * *
    (6) Each plan shall provide that the following specific provisions 
apply on a pollutant-by-pollutant basis with respect to any regulated 
NSR pollutant associated with projects at existing emissions units at a 
major stationary source (other than projects at a source with a PAL) in 
circumstances where there is a reasonable possibility, within the 
meaning of paragraph (a)(6)(vi) of this section, that a project that is 
not a part of a major modification may result in a significant 
emissions increase of such pollutant, and the owner or operator elects 
to use the method specified in paragraphs (a)(1)(xxviii)(B)(1) through 
(3) of this section for calculating projected actual emissions. 
Deviations from these provisions will be approved only if the State 
specifically demonstrates that the submitted provisions are more 
stringent than or at least as stringent in all respects as the 
corresponding provisions in paragraphs (a)(6)(i) through (vi) of this 
section.
* * * * *
    (vi) A ``reasonable possibility'' under paragraph (a)(6) of this 
section occurs when the owner or operator calculates the project to 
result in projected actual emissions increases of at least 50 percent 
of the significant level defined

[[Page 10453]]

in paragraph (a)(1)(x) of this section for the regulated NSR pollutant.
* * * * *
    3. Section 51.166 is amended by revising paragraph (r)(6) 
introductory text and adding paragraph (r)(6)(vi) to read as follows:


Sec.  51.166  Prevention of significant deterioration of air quality.

    (r) * * *
    (6) Each plan shall provide that the following specific provisions 
apply on a pollutant-by-pollutant basis with respect to any regulated 
NSR pollutant associated with projects at existing emissions units at a 
major stationary source (other than projects at a source with a PAL) in 
circumstances where there is a reasonable possibility, within the 
meaning of paragraph (r)(6)(vi) of this section, that a project that is 
not a part of a major modification may result in a significant 
emissions increase of such pollutant, and the owner or operator elects 
to use the method specified in paragraphs (b)(40)(ii)(a) through (c) of 
this section for calculating projected actual emissions. Deviations 
from these provisions will be approved only if the State specifically 
demonstrates that the submitted provisions are more stringent than or 
at least as stringent in all respects as the corresponding provisions 
in paragraphs (r)(6)(i) through (vi) of this section.
* * * * *
    (vi) A ``reasonable possibility'' under paragraph (r)(6) of this 
section occurs when the owner or operator calculates the project to 
result in projected actual emissions increases of at least 50 percent 
of the significant level defined in paragraph (b)(23)(i) of this 
section for the regulated NSR pollutant.
* * * * *
    4. Appendix S to Part 51 is amended by revising paragraph IV.J 
introductory text and adding paragraph IV.J.6 to read as follows:
    Appendix S to Part 51--Emission Offset Interpretative Ruling.
* * * * *
    IV. * * *
    J. Provisions for projected actual emissions. The provisions of 
this paragraph IV.J apply on a pollutant-by-pollutant basis with 
respect to any regulated NSR pollutant associated with projects at 
existing emissions units at a major stationary source (other than 
projects at a source with a PAL) in circumstances where there is a 
reasonable possibility, within the meaning of paragraph IV.J.6 of this 
Ruling, that a project that is not a part of a major modification may 
result in a significant emissions increase of such pollutant, and the 
owner or operator elects to use the method specified in paragraphs 
II.A.24(ii)(a) through (c) of this Ruling for calculating projected 
actual emissions.
* * * * *
    6. A ``reasonable possibility'' under paragraph IV.J of this Ruling 
occurs when the owner or operator calculates the project to result in 
projected actual emissions increases of at least 50 percent of the 
significant level defined in paragraph II.A.10 of this section for the 
regulated NSR pollutant.
* * * * *

PART 52--[AMENDED]

    5. The authority citation for part 52 continues to read as follows:

    Authority: 42 U.S.C. 7401, et seq.

Subpart A--[Amended]

    6. Section 52.21 is amended by revising paragraph (r)(6) 
introductory text and adding paragraph (r)(6)(vi) to read as follows:


Sec.  52.21  Prevention of significant deterioration of air quality.

    (r) * * *
    (6) The provisions of this paragraph (r)(6) apply on a pollutant-
by-pollutant basis with respect to any regulated NSR pollutant 
associated with projects at existing emissions units at a major 
stationary source (other than projects at a source with a PAL) in 
circumstances where there is a reasonable possibility, within the 
meaning of paragraph (r)(6)(vi) of this section, that a project that is 
not a part of a major modification may result in a significant 
emissions increase of such pollutant, and the owner or operator elects 
to use the method specified in paragraphs (b)(41)(ii)(a) through (c) of 
this section for calculating projected actual emissions.
* * * * *
    (vi) A ``reasonable possibility'' under paragraph (r)(6) of this 
section occurs when the owner or operator calculates the project to 
result in projected actual emissions increases of at least 50 percent 
of the significant level defined in paragraph (b)(23)(i) of this 
section for the regulated NSR pollutant.
* * * * *
 [FR Doc. E7-3897 Filed 3-6-07; 8:45 am]
BILLING CODE 6560-50-P


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