[Federal Register Volume 79, Number 92 (Tuesday, May 13, 2014)]
[Proposed Rules]
[Pages 27445-27472]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2014-09458]
[[Page 27445]]
Vol. 79
Tuesday,
No. 92
May 13, 2014
Part IV
Environmental Protection Agency
-----------------------------------------------------------------------
40 CFR Part 51
Data Requirements Rule for the 1-Hour Sulfur Dioxide (SO2)
Primary National Ambient Air Quality Standard (NAAQS); Proposed Rule
Federal Register / Vol. 79 , No. 92 / Tuesday, May 13, 2014 /
Proposed Rules
[[Page 27446]]
-----------------------------------------------------------------------
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 51
[EPA-HQ-OAR-2013-0711; FRL-9903-61-OAR]
RIN 2060-AR19
Data Requirements Rule for the 1-Hour Sulfur Dioxide
(SO2) Primary National Ambient Air Quality Standard (NAAQS)
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
-----------------------------------------------------------------------
SUMMARY: The Environmental Protection Agency (EPA) is proposing a rule
directing state and tribal air agencies (air agencies) to provide data
to characterize current air quality in areas with large sources of
sulfur dioxide (SO2) emissions if such areas do not have
sufficient air quality monitoring in place to identify maximum 1-hour
SO2 concentrations. The proposed rule describes criteria for
identifying the sources around which air agencies would need to
characterize SO2 air quality. It also describes a process
and timetables by which air agencies would characterize air quality
around sources through ambient monitoring and/or air quality modeling
techniques and submit such data to the EPA. The EPA has issued separate
non-binding draft technical assistance documents on how air agencies
can conduct such monitoring or modeling. The air quality data developed
by the states in accordance with this rulemaking would be used by the
EPA in future rounds of area designations for the 1-hour SO2
National Ambient Air Quality Standards (NAAQS).
DATES:
Comments. Comments must be received on or before July 14, 2014.
Information Collection Request. Under the Paperwork Reduction Act,
comments on the information collection provisions must be received by
the Office of Management and Budget (OMB) on or before July 14, 2014.
Public Hearings. If anyone contacts the EPA requesting the
opportunity to speak at a public hearing concerning the proposed
regulation by May 23, 2014, the EPA will hold a public hearing
approximately 30 days after publication of this proposed regulation in
the Federal Register. Additional information about the hearing would be
published in a subsequent Federal Register notice.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2013-0711, by one of the following methods:
www.regulations.gov: Follow the on-line instructions for
submitting comments.
Email: a-and-r-docket@epa.gov.
Mail: Attention Docket ID No. EPA-HQ-OAR-2013-0711, U.S.
Environmental Protection Agency, 1301 Constitution Ave. NW.,
Washington, DC 20460. Mail Code: 2822T. Please include two copies if
possible. 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 the EPA, 725 17th St. NW., Washington, DC 20503.
Hand Delivery: U.S. Environmental Protection Agency, EPA
West (Air Docket), William Jefferson Clinton West Building, 1301
Constitution Avenue Northwest, Room 3334, Washington, DC 20004,
Attention Docket ID No. EPA-HQ-OAR-2013-0711, EPA Headquarters Library,
The EPA/DC Public Reading Room is open from 8:30 a.m. to 4:30 p.m.
Eastern Standard Time (EST), Monday through Friday, Air and Radiation
Docket and Information Center.
Instructions. Direct your comments to Docket ID No. EPA-HQ-OAR-
2013-0711. The EPA's policy is that all comments received will be
included in the public docket without change and may be made available
on-line at 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 www.regulations.gov
or email. The www.regulations.gov Web site is an ``anonymous access''
system, which means the EPA will not know your identity or contact
information unless you provide it in the body of your comment. If you
send an email comment directly to the EPA without going through
www.regulations.gov, your email 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, the EPA recommends that you include your name and other
contact information in the body of your comment and with any CD you
submit. If the EPA cannot read your comment due to technical
difficulties and cannot contact you for clarification, the EPA may not
be able to consider your comment. Electronic files should avoid the use
of special characters, any form of encryption and be free of any
defects or viruses. For additional information about the 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 the SUPPLEMENTARY INFORMATION section of this document.
Docket. All documents in the docket are listed in
www.regulations.gov. Although listed in the index, some information is
not publicly available, i.e., 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 www.regulations.gov or in hard copy
at the Air and Radiation Docket and Information Center in the EPA
Headquarters Library, Room Number 3334 in the William Jefferson Clinton
West Building, located at 1301 Constitution Ave. NW., Washington, DC
The Public 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.
FOR FURTHER INFORMATION CONTACT: For further general information on
this rulemaking, contact Mr. Rich Damberg, Office of Air Quality
Planning and Standards, U.S. Environmental Protection Agency, by phone
at (919) 54l-5592, or by email at damberg.rich@epa.gov; or Ms. Rhonda
Wright, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, by phone at (919) 54l-1087, or by
email at wright.rhonda@epa.gov. To request a public hearing or
information pertaining to a public hearing on this document, contact
Ms. Pamela Long, Air Quality Policy Division, Office of Air Quality
Planning and Standards (C504-01), Environmental Protection Agency,
Research Triangle Park, North Carolina 27711; telephone number (919)
541-0641; fax number (919) 541-5509; email address: long.pam@epa.gov.
SUPPLEMENTARY INFORMATION:
I. General Information
A. Does this action apply to me?
Entities potentially affected directly by this proposal include
state, local and tribal governments. Entities potentially affected
indirectly by this proposal include owners and operators of sources of
SO2 emissions (such as coal-fired power plants, refineries,
smelters, pulp and paper related facilities, chemical
[[Page 27447]]
manufacturing and facilities with industrial boilers for power
generation) that contribute to ambient SO2 concentrations,
as well as people whose air quality is affected by these facilities.
B. What should I consider as I prepare my comments for the EPA?
1. Submitting CBI. Do not submit this information to the EPA
through www.regulations.gov or email. Clearly mark the part or all of
the information that you claim to be CBI. For CBI information on a disk
or CD-ROM that you mail to the 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 to be 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:
Identify the rulemaking by docket number and other
identifying information (subject heading, Federal Register date and
page number).
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.
Explain why you agree or disagree; suggest alternatives
and substitute language for your requested changes.
Describe any assumptions and provide any technical
information and/or data that you used.
If you estimate potential costs or burdens, explain how
you arrived at your estimate in sufficient detail to allow for it to be
reproduced.
Provide specific examples to illustrate your concerns and
suggest alternatives.
Explain your views as clearly as possible, avoiding the
use of profanity or personal threats.
Make sure to submit your comments by the comment period
deadline identified.
C. Where can I get a copy of this document and other related
information?
In addition to being available in the docket, an electronic copy of
this notice will be posted at http://www.epa.gov/air/sulfurdioxide/implement.html.
D. What information should I know about possible public hearings?
To request a public hearing or information pertaining to a public
hearing on this document, contact Ms. Pamela Long, Air Quality Policy
Division, Office of Air Quality Planning and Standards (C504-03),
Environmental Protection Agency, Research Triangle Park, North Carolina
27711; telephone number (919) 541-0641; fax number (919) 541-5509;
email address: long.pam@epa.gov.
E. How is this document organized?
The information presented in this document 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 the EPA?
C. Where can I get a copy of this document and other related
information?
D. What information should I know about possible public
hearings?
E. How is this document organized?
II. Background for Proposal
A. The 2010 SO2 NAAQS
B. The Area Designations Process
C. History of Designations for the SO2 NAAQS
D. Use of Air Quality Modeling Information in Area Designations
for the SO2 NAAQS
E. SO2 NAAQS Preamble: Suggested Implementation
Approach
F. The EPA White Paper and Stakeholder Input
G. The EPA's February 2013 SO2 Implementation
Strategy Paper
III. Source Coverage and Emission Threshold Options
A. Background
B. Proposed Source Emission Threshold Options
IV. Data Requirements and Program Implementation Timeline
A. From Promulgation of This Rulemaking to January 15, 2016: Air
Agency and the EPA Regional Office Consult on List of SO2
Sources; Air Agency is Required To Submit its List of Sources Along
With Its Election of Monitoring or Modeling for Characterizing Air
Quality to the EPA Regional Administrator
B. January 15, 2016: Air Agency Is Required To Submit Modeling
Protocols for Sources That Will Be Characterized With Modeling
C. July 2016: Annual Monitoring Network Plans Due to the EPA
Regional Administrator Should Include SO2 Monitoring
Network Modifications Intended To Satisfy the Data Requirements Rule
D. January 1, 2017: SO2 Monitors Intended To Satisfy
the Data Requirements Rule Are Required To Be Operational
E. January 13, 2017: States Electing To Model Are Required To
Provide Modeling Analyses to the EPA Regional Administrators
F. By August 2017: Expected Date by Which the EPA Would Notify
States of Intended Designations
G. December 2017: Intended Date by Which the EPA Would Issue
Final Designations for a Majority of the Country
H. August 2019: Anticipated Due Date for State Attainment Plans
for Areas Designated Nonattainment in 2017
I. May 2020: Required Certification of 2019 Monitoring Data;
States Have the Opportunity To Provide Updated State Recommendations
to the EPA Regional Administrators
J. August 2020: Expected Date by Which the EPA Would Notify
States of Intended Designations for the Remainder of the Country Not
Yet Designated
K. December 2020: Intended Date by Which the EPA Would Issue
Final Designations for the Remainder of the Country
L. August 2022: Anticipated Due Date for State Attainment Plans
for Areas Designated Nonattainment in 2020
V. Technical Considerations
A. Monitoring
B. Modeling
VI. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
B. Paperwork Reduction Act
C. Regulatory Flexibility Act
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 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
Statutory Authority
List of Subjects
II. Background for Proposal
A. The 2010 SO2 NAAQS
On June 2, 2010, the EPA Administrator signed a final rule that
revised the primary SO2 NAAQS under section 109 of the Clean
Air Act (CAA or Act) to provide requisite protection of public health
with an adequate margin of safety (75 FR 35520, June 22, 2010).
Specifically, the EPA promulgated a new 1-hour daily maximum primary
SO2 standard at a level of 75 parts per billion, based on
the 3-year average of the annual 99th percentile of 1-hour
[[Page 27448]]
daily maximum concentrations.\1\ The revised SO2 NAAQS will
improve public health protection, especially for children, the elderly
and people with asthma. These individuals are more susceptible to the
health problems associated with breathing SO2 than
individuals from the general population.
---------------------------------------------------------------------------
\1\ The standard is defined in 40 CFR 50.17(a)-(b). The 3-year
average of the annual 99th percentile of 1-hour daily maximum
concentrations is referred to as the ``design value.'' The design
value is compared to the level of the standard to determine whether
air quality at that location meets the standard.
---------------------------------------------------------------------------
The reaction of SO2 with other pollutants in the
atmosphere and the resulting long-range contribution of SO2
to regional air pollution problems such as fine particle formation and
acidic deposition are well-understood effects of SO2
emissions. However, SO2 as a directly emitted pollutant can
also cause relatively localized health impacts. For example, in
previous guidance, the EPA has indicated a general guideline that the
distance between a source and the maximum ground level concentration of
SO2 is generally 10 times the stack height in flat
terrain.\2\ This means that maximum concentrations can be expected to
be observed within 1-2 miles of some large power plants and other
facilities. It is important to recognize, however, that conditions such
as unique terrain features and associated meteorological conditions can
impact the location and magnitudes of significant concentration
gradients.
---------------------------------------------------------------------------
\2\ See March 1, 2011, memorandum from Tyler Fox, EPA Office of
Air Quality Planning and Standards, ``Additional Clarification
Regarding the Application of Appendix W Modeling Guidance for the 1-
hr NO2 NAAQS.'' Research Triangle Park, North Carolina
27711. This memo is available at: http://www.epa.gov/ttn/scram/Additional_Clarifications_AppendixW_Hourly-NO 2
2- NAAQS--FINAL--03-01-2011.pdf. See also the December
2013 ``Draft SO2 NAAQS Designations Modeling Technical
Assistance Document,'' issued by EPA Office of Air Quality Planning
and Standards, available at http://www.epa.gov/airquality/sulfurdioxide/pdfs/SO2 ModelingTAD.pdf.
---------------------------------------------------------------------------
The SO2 standard was established with a 1-hour averaging
time particularly to protect sensitive individuals from respiratory
effects associated with short-term exposures to SO2. Thus,
from an air quality management perspective, the SO2 NAAQS
can be considered to be a largely ``source-oriented'' NAAQS rather than
a ``regional'' one (i.e., more similar to the lead NAAQS than to the
ozone NAAQS). Strategies to attain the SO2 NAAQS are
expected to be focused on key point sources. The largest sources of
SO2 include coal-fired electric utilities, industrial
boilers, refineries, pulp and paper-related industries and chemical
manufacturing.
B. The Area Designations Process
When a NAAQS is revised, CAA provisions trigger various actions and
implementation responsibilities for air agencies \3\ and the EPA. Two
important milestones are: (1) The area designations process under CAA
section 107 and subsequent nonattainment area plan development under
CAA sections 172 and 191-192, and (2) submittal of ``infrastructure''
plans by air agencies within 3 years of NAAQS promulgation under
section 110(a)(1)-(2) of the CAA.
---------------------------------------------------------------------------
\3\ ``Air agency'' refers to the air quality management agency
of the relevant state government or tribal nation.
---------------------------------------------------------------------------
The area designations process typically relies on air quality
concentrations characterized by ambient monitoring data collected by
the air agency to identify areas that are either meeting or violating
the relevant standard. Air agencies are required to provide the EPA
with area recommendations and supporting technical information within 1
year after a standard is revised. The EPA considers this information
and commonly sends a letter to the air agency (at least 120 days prior
to finalizing the designation) that describes its intended designation
and boundaries of the nonattainment areas and other areas in the state.
During this 120-day period, the air agency has the opportunity to
demonstrate why an EPA-intended modification to its recommendation
would be inappropriate. The EPA then finalizes the area designations
process by sending letters to each governor and publishing the NAAQS
designations for each state (and tribal area, as appropriate) in the
Federal Register. The final designations are listed in 40 CFR part 81.
Once an area is designated as nonattainment for the SO2
NAAQS, CAA section 191 directs the air agency to submit to the EPA
within 18 months of designation a NAAQS attainment plan that
demonstrates, typically through air quality dispersion modeling, how
the area would attain the standard as expeditiously as practicable, but
no later than 5 years after designation as provided by section 192. CAA
section 172 lists additional elements that NAAQS attainment plans are
to contain. The air quality modeling for an attainment demonstration
needs to ensure that the area would attain even if all contributing
sources emitted at ``permitted allowable'' levels. The specifications
of attainment demonstration modeling techniques are described in 40 CFR
part 50, Appendix W.
C. History of Designations for the SO2 NAAQS
The original SO2 NAAQS \4\ were established in 1971, and
the EPA originally designated nonattainment areas for the prior
SO2 NAAQS in March 1978.\5\ The Federal Register final rule
for this action noted that certain areas were designated on the basis
of modeling data: ``In the absence of sufficient monitored air quality
data, other evaluation methods were used, including air quality
dispersion modeling.'' In a September 11, 1978, supplement to the March
3, 1978, final rule, the EPA responded to commenters and upheld certain
designations based on modeling information.\6\ A second supplement to
the March 1978 designations notice affirmed the use of modeling for
SO2 designations and determining air quality status, stating
that, ``the EPA's policy related to designations for SO2
permit the use of either modeling or monitoring to determine attainment
status.'' \7\
---------------------------------------------------------------------------
\4\ See 36 FR 8186 (April 30, 1971).
\5\ See 43 FR 8962 (March 3, 1978).
\6\ See 43 FR 40416 (September 11, 1978).
\7\ See 43 FR 40502 (September 12, 1978).
---------------------------------------------------------------------------
Five years later, in 1983, the EPA conducted a review of all
section 107 NAAQS designations made to date. A related EPA memo,
``Section 107 Designation Policy Summary,'' identified the importance
of modeling information for source-oriented pollutants in cases where
existing monitors did not adequately characterize peak concentrations:
``In general, all available information relative to the attainment
status of the area should be reviewed. These data should include the
most recent eight consecutive quarters of quality-assured,
representative ambient air quality data plus evidence of an implemented
control strategy that the EPA had fully approved. Supplemental
information, including air quality modeling, emissions data, etc.,
should be used to determine if the monitoring data accurately
characterize the worst case air quality in the area.'' \8\
---------------------------------------------------------------------------
\8\ Memorandum From Sheldon Myers, Director, EPA Office of Air
Quality Planning and Standards, to Regional Office Air Division
Directors. ``Section 107 Designation Policy Summary.'' April 21,
1983.
---------------------------------------------------------------------------
D. Use of Air Quality Modeling Information in Area Designations for the
SO2 NAAQS
Past area designations processes for most NAAQS (such as for ozone)
having violations caused and contributed to by multiple sources over a
broad region have relied primarily on air quality monitoring data to
identify areas that
[[Page 27449]]
violate the standard. However, it is important to note, as the EPA
explained in the final 2010 SO2 NAAQS preamble, that there
is a long history of also using dispersion modeling information to
inform area designations for the SO2 NAAQS. See, e.g., 75 FR
at 35551-3. The EPA and the air quality management community have
recognized over many years that peak concentrations of SO2
are commonly caused by one or a few major point sources in an area and
peak concentrations are typically observed relatively close to the
source. Many factors influence the observed SO2
concentrations around emissions sources, including the sulfur content
of fuel that is combusted, the sulfur content of material being heated
as part of an industrial process, the rate of SO2 emissions
per hour, stack height, topography, meteorology, monitor location and
source operating schedule. But because ambient SO2
concentrations are not the result of complex chemical reactions (unlike
ozone or PM2.5), they can be modeled accurately using well-
understood air quality modeling tools, especially in areas where one or
only a few sources exist. In the 1970's, when the original
SO2 NAAQS were established, there were significantly more
SO2 monitors in operation nationally than today. Even then,
the EPA and air agencies acknowledged the utility of modeling in order
to inform area designations under the SO2 NAAQS. See e.g.,
43 FR 45993, 45994-46002 (Oct. 5, 1978).
Over time, air agencies have operated monitoring networks to
characterize SO2 concentrations as effectively as possible.
However, the ambient SO2 monitoring network has declined in
number since its peak of approximately 1,500 monitors in 1980 to its
current size of approximately 450 monitors (as of June 2013), due to
improving air quality and, more recently, due to increasingly limited
resources at the local, state and federal levels. As part of the 2010
SO2 NAAQS review, the EPA conducted an analysis of the
existing monitoring network to inform potential updates to
SO2 minimum monitoring requirements that might accompany a
revised NAAQS. The study concluded that only up to a third of the
SO2 monitors in operation at the time were sited to
characterize peak 1-hour ambient SO2 concentrations. The EPA
acknowledged this in the SO2 NAAQS final preamble: ``In
preparation for the SO2 NAAQS proposal, the EPA conducted an
analysis of the approximately 488 SO2 monitoring sites
operating during calendar year 2008 (Watkins and Thompson, 2009). This
analysis indicated that approximately 35 percent of the sites in the
monitoring network were addressing locations of maximum (highest)
concentrations, likely linked to a specific source or group of sources.
Meanwhile, just under half (~46 percent) of the sites were reported to
be for the assessment of concentrations for general population
exposure. These data led the EPA to conclude that the network was not
properly focused to support the revised NAAQS, given the EPA's belief
at the time that source-oriented monitoring data would be a primary
tool for assessing compliance with the NAAQS.'' \9\ While the current
ambient SO2 monitoring network does serve multiple
monitoring objectives (which includes some source-oriented monitoring),
on the whole, the network is not appropriately positioned or of
adequate size for purposes of the 2010 SO2 standard to
characterize the air quality around many of the nation's larger
SO2 sources in operation today.
---------------------------------------------------------------------------
\9\ See 75 FR 35557 (June 22, 2010). See also Watkins and
Thompson. (2009). SO2 Network Review and Background;
OAQPS; Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, NC. Sulfur
Dioxide NAAQS Review Docket (OAR-2007-0352-0037). Available at
http://www.regulations.gov.
---------------------------------------------------------------------------
In implementation of the prior SO2 NAAQS, the EPA thus
relied upon both modeling and monitoring to inform decisions regarding
whether areas were violating the NAAQS. See e.g., 67 FR 22168, 22170-71
(May 2, 2002). This historical use of modeling along with monitoring
has been affirmed as technically valid and lawful under the CAA by
reviewing courts. See e.g., Montana Sulphur & Chemical Co. v. the EPA,
666 F.3d 1174, 1185 (9th Cir. 2012); PPG Industries, Inc. v. Costle,
630 F.2d 462, 467 (6th Cir. 1980). Because of the inherent challenges
in characterizing peak SO2 ambient air quality strictly
through monitoring techniques, past EPA SO2-related
designations actions, state implementation plan (SIP) approval and
disapproval rulemakings, federal implementation plan rulemakings and
non-binding guidance have recognized that air quality modeling can be
appropriately used to identify areas that are meeting or violating the
SO2 NAAQS, and can be used to confirm air quality monitoring
data when an area is seeking redesignation to attainment.
The EPA believes that existing air quality modeling tools are
technically sound and historically have been used when monitoring data
were not available; therefore, the EPA considers these modeling tools
appropriate for use in combination with ambient monitoring data for
assessing air quality impacts from SO2 emissions. The EPA
has recently issued a draft modeling technical assistance document
(TAD) \10\ suggesting an approach that could be used by states to
characterize SO2 concentrations around SO2
sources using the AERMOD \11\ model with actual emissions data, actual
meteorological data and actual stack height information. More details
on the EPA's modeling TAD are provided in section V, Technical
Considerations.
---------------------------------------------------------------------------
\10\ The Draft SO2 NAAQS Designations Modeling
Technical Assistance Document can be found at http://www.epa.gov/airquality/sulfurdioxide/pdfs/SO2ModelingTAD.pdf.
\11\ ``AERMOD'' stands for the American Meteorological Society/
EPA Regulatory Model.
---------------------------------------------------------------------------
E. SO2 NAAQS Preamble: Suggested Implementation Approach
The preamble to the final SO2 NAAQS issued in 2010 noted
that although the current SO2 ambient monitoring network
included 400+ monitors nationwide, the scope of the network had certain
limitations and approximately two-thirds of the monitors were not
located to characterize maximum concentration, source-oriented impacts.
In order to address potential public health impacts in areas without
adequate monitoring that could be experiencing SO2
concentrations that violate the NAAQS, in the June 2010 SO2
NAAQS preamble the EPA recommended, but did not require, that air
agencies characterize air quality in these areas with limited
monitoring through the use of air quality modeling, and adopt
substantive emission limitations to ensure attainment of the
SO2 NAAQS where the modeling indicated a violation. The
preamble stated that the EPA expected that such analyses and emission
limitations would be submitted as part of the section 110(a)(1)
infrastructure plans due in June 2013 in order to demonstrate how areas
with sources emitting over 100 tons of SO2 per year would
attain and maintain the NAAQS in the future. The EPA subsequently
issued draft implementation guidance in September 2011, which further
described this suggested approach and requested comments from the
public.\12\
---------------------------------------------------------------------------
\12\ The draft guidance for 1-Hour SO2 NAAQS SIP
Submissions can be found at http://www.epa.gov/oaqps001/sulfurdioxide/pdfs/DraftSO2Guidance--9-22-11.pdf.
---------------------------------------------------------------------------
A number of commenters on the draft guidance expressed concern with
the suggested implementation approach and some challenged this approach
in court
[[Page 27450]]
as part of the final SO2 NAAQS rule.\13\ Many commenters
maintained that areas should be designated as nonattainment first,
before they are expected to provide technical analyses and adopt
enforceable emission limitations demonstrating attainment. They claimed
that the recommended approach in effect bypassed the designation
process for areas without adequate monitoring, frustrating the
preferred sequence in implementing NAAQS under the CAA. A number of
commenters were concerned about the level of effort and resources
needed to develop plans that essentially required modeling for all
sources with annual SO2 emissions exceeding 100 tons. (There
were more than 1,680 sources across the country exceeding 100 tons of
actual emissions based on 2008 national emissions inventory data. Based
on data from the 2011 National Emissions Inventory, there are about
1500 sources exceeding 100 tons of annual SO2 emissions.) It
was also pointed out that the statutory due date of June 2013 for the
section 110 infrastructure plans (which would have included control
requirements based primarily on modeling information under the EPA's
then-suggested approach) would come well before the attainment plan
submittal due date for areas to be designated as nonattainment. (At the
time the draft guidance was issued in September 2011, the EPA was
planning to issue final designations in June 2012, meaning that
nonattainment area plans would have been due 18 months from the
effective date of designations, or approximately in February 2014.)
\14\
---------------------------------------------------------------------------
\13\ On July 20, 2012, the D.C. Circuit Court of Appeals issued
a decision upholding the 2010 SO2 NAAQS. See National
Environmental Development Association's Clean Air Project v. EPA,
No. 10-1252 (D.C. Cir. July 20, 2012). The U.S. Supreme Court
declined to hear an appeal of this decision.
\14\ Note that on July 27, 2012, the EPA announced that it was
extending the deadline for the initial round of SO2 NAAQS
area designations by an additional year, to June 3, 2013, which thus
compounded this timing discrepancy in many commenters' views.
---------------------------------------------------------------------------
F. The EPA White Paper and Stakeholder Input
1. Background
In response to the comments received on the draft implementation
guidance issued in September 2011, the EPA Assistant Administrator for
Air and Radiation, Gina McCarthy, sent letters to state Environmental
Commissioners on April 12, 2012, indicating that the EPA wanted to
further consult with stakeholders regarding how to best implement this
standard and protect public health in an effective manner. The letters
also stated that the EPA would not expect air agencies to submit
substantive attainment demonstrations and emission limitations by June
2013 (as part of section 110(a) infrastructure plans) for areas not
designated as ``nonattainment,'' but would expect those submittals to
resemble more traditional infrastructure SIPs.
The EPA then issued a May 2012 paper titled, ``Implementation of
the 2010 Primary 1-Hour SO2 NAAQS: Draft White Paper for
Discussion'' (White Paper) on possible alternative approaches for
implementing the SO2 standard.\15\ The EPA convened 3
stakeholder meetings to discuss the White Paper in May and June of 2012
with, respectively, environmental group representatives; state, local
and tribal air agency representatives; and industry representatives.
The EPA also accepted written comments on the White Paper from
interested parties through the end of June.
---------------------------------------------------------------------------
\15\ The May 2012 White Paper and high-level summaries of
stakeholder meetings are available at: http://www.epa.gov/oaqps001/sulfurdioxide/implement.html. These documents and written comments
received from stakeholders are also included in the docket for this
rulemaking.
---------------------------------------------------------------------------
In the White Paper and during the stakeholder meetings, the EPA
framed the basic challenge of how to more broadly characterize 1-hour
SO2 concentrations in priority locations across the country
such that these data could inform future area designations for the
SO2 NAAQS, while taking into consideration limited EPA and
air agency resources. The paper noted that peak 1-hour concentrations
of SO2 are most commonly observed in relatively close
proximity to emission sources, yet many monitors in the current
SO2 ambient monitoring network are not sited in appropriate
locations to document these peak concentrations. Thus, many existing
monitors are in effect ``under-reporting'' peak 1-hour concentrations.
The White Paper indicated that there are more than 20,000
SO2 sources nationally and to add a significant number of
ambient monitors to the national network to adequately characterize
peak concentrations would take significant resources. The EPA estimates
that the capital costs of siting a new monitor can be on the order of
$50,000 to $100,000. Routine operations and maintenance costs would be
in addition to those up-front capital costs.
Given this background, the White Paper described two monitoring-
focused approaches and one modeling-focused approach for characterizing
peak 1-hour SO2 concentrations, and it outlined a range of
policy, technical, and implementation issues and questions associated
with each approach. The issues and questions highlighted in the White
Paper were discussed in depth during the stakeholder meetings. The
White Paper and high-level summaries of each meeting are available on
the EPA's SO2 implementation Web site.\16\
---------------------------------------------------------------------------
\16\ See http://www.epa.gov/airquality/sulfurdioxide/implement.html.
---------------------------------------------------------------------------
2. Monitoring and Modeling Approaches Described in White Paper
Two possible monitoring-focused approaches were described in the
White Paper. The White Paper indicated that about 440 SO2
monitors were operational as of April 2012, but only about a third of
those monitors might be considered to be in ``source-oriented''
locations. Thus, if air agencies were to implement a monitoring-only
approach without supplemental data from modeling, a number of monitors
would either need to be moved within the existing network and/or a
number of new monitoring sites would need to be established.
The first monitoring-based approach described in the White Paper
would involve air agencies reallocating the monitors that are not
source-oriented and otherwise not required to be in their current
locations to be moved to source-oriented locations, and then adding
additional monitors as necessary to address all areas warranting
further characterization of air quality. For example, such a network
might be designed to characterize air quality for about 550 sources
with annual emissions greater than 2,000 tons, which in total would
account for about 93 percent of nationwide SO2 emissions
(based on 2008 national emission inventory data). This option would
identify source areas for monitoring based on a single emissions
threshold. It would focus on providing air quality characterization
around the largest sources and would not provide additional emphasis on
sources located in highly populated areas.
The second monitoring-focused option presented in the White Paper
was an extension of the Population Weighted Emissions Index (PWEI)
concept that was included in the 2010 SO2 NAAQS ambient
monitoring requirements. The PWEI was established to define monitoring
requirements for Core Based Statistical Areas (CBSAs) based on
calculations using the total SO2 emissions and total
population in the area. This suggested option in the White Paper would
require approximately 400 sources located in areas with a high PWEI and
having SO2
[[Page 27451]]
emissions over 750 tons per year (tpy) to have source-oriented
monitoring; and an estimated 170 additional sources located outside
those PWEI areas having emissions over 5,000 tpy to have source-
oriented monitoring. This option also would account for more than 90
percent of nationwide SO2 emissions (based on 2008 national
emission inventory data).
Thus, both monitoring-only approaches, using the example cutoffs
identified in the White Paper, were estimated to provide for the
characterization of air quality for at least 500 sources that accounted
for at least 90 percent of national emissions (based on 2008 emissions
data).\17\ One key difference between the 2 options was that the second
option provided some additional emphasis on ensuring the
characterization of air quality in areas with relatively higher
populations.
---------------------------------------------------------------------------
\17\ Based on 2008 emissions data, about 480 sources with actual
emissions exceeding 2,800 tons per year accounted for 90 percent of
national SO2 emissions.
---------------------------------------------------------------------------
The White Paper also included discussion of a modeling-based
approach, in which air quality dispersion modeling with AERMOD would be
used to characterize air quality for areas in which the largest
SO2 sources are located. The EPA presented this potential
approach because air quality modeling has been used for SO2
designations in the past, and conducting air quality modeling analyses
for SO2 would likely be less resource intensive than the
full-scale expansion and operation of the ambient monitoring network
described in the Paper. Under this approach, modeling would be required
to characterize air quality in areas in which sources exceeding a
specified emissions threshold are located.
3. Comments on Monitoring-Based Approaches
In the May-June 2012 stakeholder meetings and written comments
received thereafter, a number of stakeholders, including several state
and local air agency representatives, expressed a preference for the
use of ambient monitoring alone to characterize air quality
SO2 concentrations. They indicated that, since the 1970s,
ambient monitoring has been the traditional approach for characterizing
air quality to assess compliance with all other NAAQS. They claimed
that the expanded use of air quality modeling to characterize
SO2 concentrations, as described in the draft September 2011
guidance, would not be appropriate because they believed that modeling
techniques inherently over-predict SO2 concentrations by
assuming a constant rate of peak emissions and worst-case
meteorological conditions.
Commenters from some of the states with the greatest number of
large SO2 sources (such as Ohio, Indiana and Pennsylvania)
indicated that for each source, as many as 3 monitors or more might be
needed to adequately characterize 1-hour SO2 concentrations
around the source, in order to avoid monitoring that underestimates
maximum SO2 concentrations.\18\ Some also recommended the
addition of an onsite meteorological station near each source to aid
monitoring data analysis.
---------------------------------------------------------------------------
\18\ See, for example, comments from Ohio EPA, docket number
EPA-HQ-OAR-2010-1059-0123.
---------------------------------------------------------------------------
Representatives from environmental organizations did not favor
monitoring-based approaches. They emphasized the importance of
characterizing air quality in priority areas expeditiously in order for
such data to be used in the area designations process and monitoring
approaches would take several years to site new monitors and collect 3
years of data. They pointed out that high 1-hour concentrations can
occur in any direction around a source and that state air agencies
would not have the resources to provide for multiple monitors around
priority sources.
While some air agencies nevertheless maintained a preference for
ambient monitoring, a number of them also expressed the concern that it
would be difficult to expand their SO2 networks with
additional air quality monitors as needed because state budget
resources are very limited today. Some commented that from a practical
standpoint, if an expanded SO2 monitoring network was to be
established, it would need to be funded by the federal government, or
by the source owners themselves. In contrast, a number of commenters
representing sources of SO2 emissions or industry
associations maintained that ambient air quality monitoring to protect
public health should be a governmental responsibility, rather than the
responsibility of the emissions sources themselves. Some industry
representatives indicated that they operate their own monitoring
networks and could explore with corresponding air agencies the
possibility of using data from such monitors under a monitor-based
approach. Such monitors would need to meet the EPA's quality-assurance
requirements, the data would need to be made publicly available and an
agreement for long-term operation and funding would need to be
considered.
Thus, while ambient monitoring appeared to be the favored
methodology by a number of stakeholders, there were very pragmatic
concerns expressed about the cost of expanding current networks
sufficiently to ensure proper coverage and uncertainty about how many
new monitors could be established in actuality. Some air agency
representatives remarked that if modeling is also recognized as an
acceptable approach for characterizing air quality, then they would be
open to both approaches, as long as the state has the flexibility to
use the analytical method that would make the most sense for each
identified source area, considering the coverage of the state's
existing monitoring network, various resource and staffing
considerations, and other factors.
4. Comments on Modeling Approach
Environmental group representatives generally favored the use of
modeling, citing the EPA's prior policy and various regulatory
precedents in which modeling has been used to characterize
SO2 air quality. They emphasized that modeling can be done
more quickly, with less expense and for more locations (including
locations where physically siting a monitor would be very difficult)
than monitoring. They indicated that the cost of modeling assessments
for certain source areas could be done for less than $10,000.
Many air agency and industry commenters asserted that if the
September 2011 draft modeling guidance for attainment plans (which,
consistent with longstanding guidance and practice in SO2
attainment planning, recommended the use of allowable, not actual,
emissions rates) is maintained as the guidance for characterizing
current air quality and is used for designations purposes, it would
lead to significant over-predictions of 1-hour SO2
concentrations. Some commenters opposed the use of modeling at all for
this reason, without suggesting ways to correct this asserted over-
prediction. Some commenters also cited specific technical issues with
the AERMOD model (such as the treatment of low wind speed conditions
and the treatment of building ``downwash'' conditions) which they
believe contribute to the over-prediction of air quality
concentrations.
A number of commenters did not oppose modeling outright, but
suggested that if modeling is part of the EPA's overall approach, the
EPA should allow air agencies to conduct modeling based on actual
emissions, since modeling in this context in effect would serve as a
surrogate to comprehensive ambient
[[Page 27452]]
monitoring, while overcoming the current monitoring network's relative
lack of coverage. For example, the Florida Department of Environmental
Protection provided an example analysis in their comments which showed
modeled air quality results using actual emissions inputs in close
agreement with monitored air quality values near a large emission
source in Florida.\19\
---------------------------------------------------------------------------
\19\ See Docket item the EPA-HQ-OAR-2010-1059-0172, June 29,
2012, letter from Florida Department of Environmental Protection
with comments on the EPA's April 2012 SO2 White Paper.
---------------------------------------------------------------------------
The EPA notes that the reason the draft modeling guidance issued in
September 2011 recommended the use of the source's allowable emissions
rate in the modeling analysis is because it was developed for
predictive situations, such as when an air agency would be
demonstrating attainment for the future, where use of allowable
emissions rates is common for providing assurance that the prediction
includes a full range of potential emissions scenarios. However, the
EPA acknowledges that for the purpose of characterizing current \20\
air quality, it is reasonable for modeling presumptively to use actual
emissions data and/or actual 1-hour emission rates as an input in order
to most closely represent ambient monitoring results. The EPA has
concluded that using actual emissions data and meteorological data as
inputs to AERMOD modeling can adequately characterize peak
concentrations in multiple directions around a source. Note also that
after considering the White Paper comments, the EPA developed the draft
SO2 NAAQS Designations Modeling TAD that recommends using
AERMOD to estimate air quality concentrations near a large
SO2 source by using actual emissions data (such as 1-hour
emissions rates from continuous emission monitors) and meteorological
data from appropriate proximate nearby locations.\21\
---------------------------------------------------------------------------
\20\ ``Current'' air quality in this context refers to the air
quality indicator that may be used by the EPA for various regulatory
decisions in a future designations process (e.g., the most recent 3
years of monitoring data).
\21\ While the use of actual emissions data is recommended in
the draft modeling TAD, there may be situations where the use of
allowable emissions rates to characterize current air quality may be
beneficial for the air agency or source to show that even with this
type of conservative assumption, the source area would be expected
to attain the standard. One benefit of an analysis demonstrating
attainment of the 1-hour standard based on allowable emission rates
is that it would avert the need for recurring review to determine
whether emission increases have created new potential for NAAQS
violations.
---------------------------------------------------------------------------
In light of the practical concerns about the cost of adding new
ambient monitors, the uncertainty (at the time of the stakeholder
meetings) about whether actual emissions would be able to be used for
air quality modeling for this purpose, and how accurate the predictive
results of such modeling would be, many commenters suggested that air
agencies should be provided the flexibility to choose whichever
approach makes the most sense on a case-by-case basis for
characterizing air quality around each priority source in the state. In
addition, based on comments received on the White Paper regarding state
resource concerns, it appears that some air agencies likely will need
to rely primarily on air quality modeling techniques.
5. Comments on Emissions Threshold
While there was not consensus with respect to using a single
approach for characterizing air quality from SO2 sources,
one issue that all parties involved in the stakeholder discussions
generally agreed upon was the concept of having a ``threshold'' of some
sort to identify the largest sources around which ambient air quality
would need to be characterized to inform future rounds of area
designations. A number of stakeholders commented that, given current
budgetary and other constraints on resources for characterizing air
quality through either monitoring or modeling, focusing on the largest
sources of emissions would be a reasonable approach for prioritizing
sources to be evaluated for purposes of assessing attainment with the
1-hour SO2 NAAQS. Many stakeholders found the basic policy
approach expressed in the White Paper (where air agencies would
characterize air quality for sources accounting for 90 percent of
national SO2 emissions for use in future designations) to be
reasonable and preferable to the approach in the September 2011
guidance (where air agencies were expected to demonstrate attainment
around all sources in the state emitting more than 100 tons of
SO2 per year).
Some commenters offered recommendations for specific SO2
thresholds based on annual emissions or other factors that would define
which sources air agencies would be expected to characterize through
monitoring or modeling in the future. Some commenters suggested single
threshold levels ranging from 100 to 5,000 tons of SO2
emissions per year. A few commenters suggested a phased approach, in
which larger sources (e.g., 2,000 tpy and larger) would be addressed in
an initial phase and smaller sources (e.g., 500-2,000 tpy) would be
addressed in a second phase 2 or more years later.\22\ Several
commenters observed that because the SO2 NAAQS is a 1-hour
standard, a potentially more appropriate metric for a threshold would
be one based on hourly emissions rates rather than tpy. Others
recognized, however, that 1-hour emissions data are not readily
available for many types of emissions sources other than electric
generating units (EGUs) (which commonly operate continuous emissions
monitors (CEMs)).
---------------------------------------------------------------------------
\22\ Comments on the EPA White Paper from the Georgia Department
of Natural Resources, EPA Docket ID No. EPA-HQ-OAR-2010-1059-0136,
June 29, 2012.
---------------------------------------------------------------------------
Some commenters stated that because protection of public health is
the principal objective of the SO2 NAAQS, a program to
direct air agencies to characterize SO2 concentrations
around large SO2 sources should include some specific
emphasis on sources located in areas with higher populations. Some
suggested that other factors such as the height of emissions stacks,
proximity to sensitive receptors (i.e., schools, hospitals, nursing
homes), or source compliance record should also be considered in
establishing a threshold-based approach.
6. Comments on Program Implementation
A number of stakeholders provided comments on the timing of
implementation for any program requiring air agencies to further
characterize peak 1-hour SO2 concentrations. Many commenters
stated that any new modeling or monitoring requirements should be
established through a notice-and-comment rulemaking process. In
addition, a number of air agency representatives indicated that the
program needs to be structured in such a way that allows for sufficient
time to conduct the necessary monitoring or modeling, citing the large
number of sources to be addressed (even with a threshold), limited
resources and the stringency of the 1-hour standard. The proposed
timeline for implementation is discussed in more detail in section IV
of this preamble.
The input received from stakeholders during these meetings and in
written comments was invaluable to informing the EPA's refinement of
its SO2 implementation strategy, which was released in
February 2013 and is discussed in the next section. Input from the
stakeholder meetings and comments on the White Paper also informed the
recent TADs on
[[Page 27453]]
monitoring \23\ and modeling for designations.
---------------------------------------------------------------------------
\23\ The Draft SO2 NAAQS Designations Source-Oriented
Monitoring Technical Assistance Document can be found at http://www.epa.gov/airquality/sulfurdioxide/pdfs/SO2MonitoringTAD.pdf.
---------------------------------------------------------------------------
G. The EPA's February 2013 SO2 Implementation Strategy Paper
On February 13, 2013, as part of the initial area designations
process, the EPA notified air agencies that we intended to designate 30
areas as nonattainment, based on monitored violations of the
SO2 NAAQS.\24\ We also notified air agencies that the EPA
was not yet prepared to propose designations for other areas without
violating monitors. On the same day, the EPA also issued an
implementation strategy paper titled, ``Next Steps for Area
Designations and Implementation of the SO2 NAAQS.'' \25\
This Strategy Paper described the agency's plan for addressing public
health concerns in areas other than the areas identified in initial
designation. The Strategy Paper recognizes the need to further
characterize current air quality across the country to address
important public health impacts, noting that ``the current monitoring
network provides relatively limited geographic coverage, and many
monitors in the existing network are not sited with the objective of
characterizing source-oriented maximum concentrations.'' The Paper also
supports the long-standing approach in the CAA for the EPA to designate
nonattainment areas through an orderly exchange of recommendations and
technical information between state governments and the EPA.
---------------------------------------------------------------------------
\24\ The EPA finalized nonattainment designations for 29 of
those 30 areas August 5, 2013 (78 FR 47191, 47205). The EPA took no
designation-related action on the rest of the country. Estimated
total stationary source SO2 emissions (calendar year
2011) in these areas ranged from 562 tons (lowest area) to 144,267
tons (highest area) per year.
\25\ The February 2013 SO2 NAAQS implementation
strategy paper can be found at: http://www.epa.gov/oaqps001/sulfurdioxide/implement.html.
---------------------------------------------------------------------------
The main elements of the implementation strategy include the
following:
The EPA would develop a rulemaking directing air agencies
to characterize air quality in priority source areas through either air
quality monitoring or air quality modeling and submit such data to the
EPA. The present proposal is a key step in fulfilling this aspect of
the strategy.
The rule would identify priority sources as those sources
exceeding specific thresholds based wholly or in part upon annual
emissions. Some threshold options may be ``2-pronged,'' meaning they
could include a lower threshold for sources located in metropolitan
areas larger than a certain size and a higher threshold for sources
located outside such metropolitan areas.
Prior to proposal of the rulemaking, the EPA would issue
draft TADs on siting ambient, on source-oriented SO2
monitors at locations of expected maximum concentration and on the use
of air quality modeling to characterize ``current'' air quality around
an emission source for purposes of designations recommendations.
To fulfill their requirements to characterize air quality,
states would have flexibility to choose whether to use monitoring or
modeling to characterize air quality around or in proximity to
identified sources. Air agencies would follow the timeline provided in
the rule, which would specify the dates by which they need to identify
the method to be used to characterize air quality and the date for
submitting these data to the EPA along with relevant designation
recommendations.
The EPA and air agencies would use these data to complete
two additional rounds of area designations as soon as feasible after
the data become available.
The Strategy Paper noted that this approach provides an
incentive for states and other air agencies to work with their sources
to achieve early reductions to improve public health and potentially
avoid a nonattainment designation for as many priority source areas as
possible.
With regard to identifying priority sources through source
threshold options, the Strategy Paper first discussed appropriate
monitoring objectives for a NAAQS pollutant that can have localized
impacts, such as SO2 or lead. It indicated that important
monitoring objectives should include (1) characterization of peak air
quality concentrations in the area around the source (e.g., source-
oriented and maximum concentration monitoring); and (2)
characterization of air quality in populated areas, intended to
represent ambient concentrations to which people in the area are
exposed.
To meet these two objectives, the EPA suggested the establishment
of a ``2-pronged'' emissions threshold for identifying sources for
which the air agency would need to further characterize air quality.
The paper states: ``Under such an approach, a lower threshold (e.g.,
2,000-3,000 tpy) would apply to sources located in more heavily
populated areas (e.g., CBSAs having 1,000,000 or more persons); and a
higher threshold (e.g., 5,000-10,000 tpy) would apply to sources
located in less populated areas outside of such CBSAs. To illustrate
potential coverage of possible options, a 2-pronged threshold including
3,000+ ton sources located in CBSA's with a population of 1,000,000 and
10,000+ ton sources outside of these CBSA's, would cover 202 sources
and 66 percent of national emissions. A 2-pronged threshold including
2,000+ ton sources located in CBSA's with a population of 1,000,000 and
5,000+ ton sources outside of these CBSA's, would cover 341 sources and
81 percent of national emissions.''
The Strategy Paper goes on to say, ``In a future rulemaking,
factors to consider in selecting appropriate thresholds could include
the comprehensiveness of the total emissions represented; the
comparability of source coverage under this approach with typical
source coverage of an ambient monitoring network; emission levels for
sources in areas with monitored violations; and emission levels
associated with `well-controlled' sources. Upon analysis of such
factors, the EPA would expect to propose a range of threshold options
for a minimum level of coverage (preliminary estimates suggest that
this range could cover sources accounting for 66 percent to 90 percent
of national SO2 emissions). In addition, the basis for the
emissions that would be compared to the threshold (e.g., highest of the
most recent 3 years of data) would need to be defined in the
rulemaking.''
III. Source Coverage and Emission Threshold Options
A. Background
This section discusses the proposed ``threshold'' options for
identifying source areas for future air quality characterization and
the factors that the EPA considered in developing them. The EPA
believes the key objective to be achieved by using SO2
source emission thresholds would be to focus the limited available
resources at the local, state and federal levels toward characterizing
air quality in areas having the largest SO2 emitting sources
(and greater potential for relatively higher SO2
concentrations) but may be lacking sufficient air quality data. In
proposing source threshold options, the EPA seeks to collect additional
air quality data intended to achieve protection of public health on a
widespread basis from the adverse health effects of short-term exposure
to high SO2 concentrations. However, the EPA recognizes that
for SO2 and all other NAAQS, characterizing air quality in
areas around all sources nationally is not feasible. Thus, just as
NAAQS ambient monitoring networks are designed to
[[Page 27454]]
measure air quality in areas where the public is likely to be exposed
and violations may be likely, these SO2 threshold options
are designed to meet a similar objective. These options also provide
for the characterization of air quality in a substantial number of
source areas that account for a high percentage of the national
SO2 emissions inventory in a manner that provides
flexibility to air agencies, given existing funding and resource
constraints.
B. Proposed Source Emission Threshold Options
The purpose of establishing emission thresholds by rule will be to
identify those SO2 emissions sources for which air agencies
will be directed to either: (1) Characterize air quality through either
ambient monitoring or air quality modeling; or (2) demonstrate that
there are adequate enforceable emission limits in place for the area's
sources by January 2017 that will ensure attainment with the 1-hour
SO2 standard. We note that some commenters suggested that a
number of sources are planning to shut down during the next few years
and should not be subject to this rule. If sources have indeed shut
down by January 2017, a demonstration to that effect would also be
sufficient.
We note that air agencies may have other factors or reasons that
lead them to evaluate 1-hour air quality concentrations for
SO2 source areas other than those that may be required to be
characterized pursuant to this proposed rule. This proposed rule only
presents a minimum set of sources for which surrounding ambient air
quality would need to be characterized. As discussed in more detail in
section IV, the air agency or the EPA Regional Administrator \26\ may
identify other sources that should be characterized beyond the minimum
requirements of this proposed rule.
---------------------------------------------------------------------------
\26\ Throughout this proposed rule the ``EPA Regional
Administrator'' refers to the Regional Administrator or a delegated
representative.
---------------------------------------------------------------------------
In developing the proposed source emission threshold options, the
EPA considered two important preliminary questions: (1) What is an
appropriate metric for defining a source threshold? and (2) should
population centers be addressed by source threshold options? The EPA
considers each of these questions first before discussing the three
proposed source threshold options.
1. What are the appropriate emissions metrics for use in a threshold
approach?
The EPA's 2012 White Paper and the 2013 Strategy Paper discuss
appropriate metrics to use in establishing a threshold-based approach
to characterize ambient air quality surrounding a subset of priority
SO2 sources. In these papers, the EPA described the source
emission threshold concept in terms of the metric of annual tons of
SO2 emissions. Because the standard is expressed in terms of
a 1-hour form, a potentially more appropriate metric to use for
establishing a source threshold concept to identify priority sources
may be the 1-hour emission rate. Many EGUs are already required to
track and report 1-hour emission rates in accordance with existing
requirements to operate CEMs for compliance with existing programs.
However, most facilities in non-EGU sectors (e.g., pulp and paper
facilities, Portland cement plants, petroleum refineries, etc.) do not
currently operate CEMs nor do they collect emissions data on an hourly
basis.
Commenters on the White Paper also identified some other factors
that potentially could be used or incorporated into an approach to
identify sources for air quality characterization. These factors
include stack height, proximity to sensitive populations (e.g.,
schools, hospitals, nursing homes) and topography, among others. Some
commenters suggested that the EPA develop a complex matrix of multiple
factors for identifying sources.
The EPA recognizes that any source emission threshold approach
needs to strike a reasonable balance between the robustness of the
technical approach and the feasibility of implementing it. The EPA
believes that inclusion of factors other than emissions data in a
source threshold approach will be difficult for implementation because
current databases do not provide comprehensive data for other factors
for all SO2 candidate sources nationally. In addition, we do
not anticipate that the introduction of these multiple other potential
factors would improve the source identification approach by such a
degree that it would justify the complexity and additional
administrative burden introduced by the inclusion of such factors.
The EPA therefore is proposing that the emissions-based component
in the threshold options presented in this rulemaking be expressed in
terms of annual emissions of SO2. Annual emissions data are
available for all SO2 emissions sources over 100 tpy,
whether EGU or non-EGU, and thus providing a stable and common metric
for large sources. Requirements for the submittal of such data already
are found in existing regulations for large SO2 sources,
whereas submittal of 1-hour emissions data is not currently required
for all large sources of SO2. Thus, an annual emissions-
based approach would not impose substantial new reporting burdens on
states and sources. This metric will also allow for program
implementation based on a common and complete dataset; and importantly,
many stakeholders in past meetings have expressed support for the use
of annual emissions.
The EPA requests comment on the use of annual emissions (i.e., tons
of SO2 per year) as the metric to be used for an emissions
and population-based threshold approach, or, alternatively, for a
solely emissions-based threshold approach, to identify SO2
sources for further ambient air quality characterization with respect
to the 1-hour SO2 NAAQS. The EPA also requests comment on
any potential alternative factors that should be considered for
defining emissions thresholds, along with any information about the
availability of data related to this factor for all SO2
sources nationally, the time and resources needed to develop a database
for this additional factor, any associated technical analysis and
rationale for using these other factors in defining source thresholds.
2. Should a tighter threshold apply in more populated areas?
In the 2012 White Paper, the EPA presented the issue of whether
population exposure could have a role in the process of identifying
where limited resources should be focused in creating new air quality
data, as it historically has in designing ambient air quality networks.
In feedback received during meetings with stakeholders, commenters
varied in their opinions regarding whether there should be a
population-based aspect to the source threshold concept or not. Some
stakeholders supported a threshold based strictly on SO2
emissions, while others supported an option with both a source-oriented
component and a population-based component.
After considering these comments, the EPA in its February 2013
SO2 Strategy Paper presented example options for
establishing ``2-pronged'' source thresholds that would include a lower
emissions threshold for sources located in areas with higher population
and a higher emissions threshold for sources outside those higher
population areas. One advantage of a 2-pronged option is that it
directly addresses source-
[[Page 27455]]
oriented emissions and includes an element of population exposure. A
lower threshold for urban sources can help increase public health
protection because there are more people in an area that could be
impacted by relatively smaller sources. At the same time, the higher
threshold outside the populated areas allows resources spent on
characterizing air quality around smaller sources to be more
efficiently focused on the more populated areas.
Consistent with the February 2013 Strategy Paper, the EPA believes
it would be most prudent to design this data requirements rule to
include specific priority for characterizing air quality around sources
located in areas of higher population and therefore the potential for
greater population exposure to unsafe 1-hour SO2
concentrations. The air quality data to be developed by air agencies
will be used in protecting public health in these areas through the
area designations process. The inclusion of population exposure as an
objective in this program also would be generally consistent with the
rationale behind the PWEI concept used in the monitoring requirements
promulgated in the 2010 SO2 NAAQS final rule.
The EPA believes that in defining the population exposure component
of a source threshold approach, it is preferable to link the threshold
to population data for CBSAs. As a precedent, the EPA has recently used
the population threshold of CBSAs having 1,000,000 or more persons for
certain minimum monitoring requirements for nitrogen dioxide
(NO2), carbon monoxide and particulate matter. Further, the
recent 2013 Revision to Ambient Nitrogen Dioxide Monitoring
Requirements rule modified the dates by which required near-road
NO2 monitors are to be operational, with the first phase of
these monitors focused in CBSAs having 1,000,000 or more persons.
Based upon 2012 population estimates from the U.S. Census Bureau,
areas meeting the 1,000,000 person CBSA threshold represent
approximately 55 percent of the total U.S. population. The EPA believes
this threshold is a reasonable metric to use when there is a need to
more explicitly consider issues of concern in the nation's more
urbanized areas. Due to the recent use of this particular population
threshold, we again propose to use it as a means of demarking how a
source threshold approach might be applied in the more populated areas
of the country. The EPA requests comment on its proposed use of the 1
million person CBSA population threshold for representing the
population exposure component of the source threshold options in this
rule. The EPA also requests comment on whether to include a population
exposure-based threshold at all, and on whether alternative or
additional criteria would be appropriate to further focus resources on
characterizing air quality in areas with a higher likelihood of
population exposure. The EPA also recommends that commenters provide
appropriate supplementary information to support their comments.
3. What are the proposed options for source emission and population
thresholds?
The EPA is proposing a preferred source emission and population
threshold option and we are requesting comment on two other alternative
options. These options are summarized in Table 1 below. Data from the
emissions year of 2011 were used to calculate the number of sources
covered and the percent of national SO2 emissions covered by
each option. Total SO2 emissions in 2011 were 5.8 million
tons.
All of these options are in the form of a ``2-pronged'' approach
using both source emissions and population data. Each has a lower
annual SO2 emissions tonnage threshold for sources located
in urbanized areas (e.g., CBSAs) with a population greater than
1,000,000, and a higher annual emissions tonnage threshold for sources
located outside of such areas. These options have been developed after
taking into account comments from a number of stakeholders during
previous discussions in 2012 as discussed in section II above.
The intent of the following proposed options is to identify a
minimum set of sources meeting a common set of criteria for which
additional monitoring or modeling would be conducted to characterize
current ambient air quality in priority areas with the greatest
potential for exposure to violations of the SO2 NAAQS (such
as may be used to inform future designations under the SO2
NAAQS). However, we note that, while a state that meets these minimum
requirements would satisfy the rule, there may still be a need to
characterize air quality for other sources below the thresholds in this
rule that the air agency or the EPA Regional Administrator deems may
have the potential to violate the NAAQS. For any such source areas, the
air agency could choose whether to characterize air quality through
monitoring or modeling. In a modeling analysis, a source below the
threshold could be accounted for directly as one of the sources
included in the modeling assessment, or in some cases it could be
sufficient to account for smaller stationary and area sources of
SO2 in how background emissions are characterized in the
analysis.
The EPA is proposing Option 1, which would require ambient air
quality characterization around sources with emissions greater than
1,000 tpy which are located within any CBSA having 1,000,000 or more
persons, and around sources with emissions greater than 2,000 tpy
located outside CBSAs having 1,000,000 or more persons. Based upon 2011
emissions data and 2012 census estimates, Option 1 would identify 443
sources which account for 75 percent of the total SO2
emissions inventory located in areas currently not designated. In
addition to those sources, Table 1 also indicates that 53 sources
exceeding these thresholds were included in areas designated
nonattainment in 2013,\27\ and, according to 2011 emissions data, they
accounted for over 900,000 tons of SO2. Thus, the total
coverage of this option, including sources above the thresholds and
sources included in designated nonattainment areas, would be 496
sources and 90 percent of national SO2 emissions in 2011.
---------------------------------------------------------------------------
\27\ See EPA memorandum to the docket that identifies
SO2 emissions sources that would be covered by each
proposed source emissions threshold option, and sources located in
designated nonattainment areas.
---------------------------------------------------------------------------
The EPA notes that the ``90 percent threshold'' concept embodied in
the preferred Option 1 was first described in the May 2012 White Paper
and discussed in the May-June 2012 stakeholder meetings. A number of
stakeholders expressed general support for a threshold at this level
because, while still addressing 90 percent of the inventory, it
efficiently focused program requirements on a limited subset of the
20,000+ SO2 sources nationally, and substantially fewer
sources than the almost 1,700 100-ton sources targeted by the original
strategy discussed in the final SO2 NAAQS preamble and
September 2011 draft and the EPA guidance. Under Option 1, it is
estimated that no more than 32 sources from any one state would meet
the minimum source threshold criteria. Option 1 also is generally
consistent with the monitoring coverage provided by the lead NAAQS,
which is a standard designed primarily to address source-oriented
emissions impacts, similar to the SO2 NAAQS.
Option 2 would require ambient air quality characterization around
sources with emissions greater than 2,000 tpy that are located within
any CBSA
[[Page 27456]]
having 1,000,000 or more persons, and around sources with emissions
greater than 5,000 tpy located outside CBSAs having 1,000,000 or more
persons. Based upon 2011 emission year data and 2012 census estimates,
Option 2 would identify for characterization 270 sources that account
for 66 percent of the total SO2 emissions inventory located
in areas currently not designated.\28\ Therefore, the total coverage of
this option, including sources above the thresholds and sources
included in designated nonattainment areas, would be 323 sources and 82
percent of national SO2 emissions in 2011.
---------------------------------------------------------------------------
\28\ Options 2 and 3 were provided as examples in the February
2013 SO2 implementation strategy paper and have been
discussed with various stakeholders since that time.
---------------------------------------------------------------------------
Option 3 would require ambient air quality characterization around
sources with emissions greater than 3,000 tpy that are located within
any CBSA having 1,000,000 or more persons, and around sources with
emissions greater than 10,000 tpy located outside CBSAs having
1,000,000 or more persons. Based upon 2011 emission year data and 2012
census data, Option 3 would identify for characterization 158 sources
that account for 54 percent of the total SO2 emissions
inventory located in areas currently not designated. Thus, the total
coverage of this option, including sources above the thresholds and
sources included in designated nonattainment areas, would be 211
sources and 69 percent of national SO2 emissions in 2011.
The preferred Option 1 and the other two options are summarized in
Table 1 below with regard to emission thresholds, population
thresholds, number of sources identified for characterization and
percent of national inventory (before and after subtracting sources
already in areas designated nonattainment).
Table 1--Summary of Source Threshold Options a
--------------------------------------------------------------------------------------------------------------------------------------------------------
Threshold for sources Percent of Plus sources
---------------------------------------- Number of national in 2013 desig. Total source Total
Option Inside CBSAs Outside CBSAs sources ** emissions nonatt. areas coverage emissions
greater than 1M greater than 1M [dagger] (%) [Dagger] coverage (%)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1*............................. 1,000 TPY......... 2,000 TPY......... 443 75 53 496 90
2............................... 2,000 TPY......... 5,000 TPY......... 270 66 53 323 82
3............................... 3,000 TPY......... 10,000 TPY........ 158 54 53 211 69
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ The emissions in this table are based on the 2011 National Emissions Inventory (NEI) and differ from the information in the February 2013 Strategy
Paper, which was based on the 2008 NEI and preliminary 2011 data. These numbers are also based on the 2013 CBSA definitions.
* Preferred option.
** These do not include sources located in nonattainment areas designated in 2013.
[dagger] Total SO2 emissions in 2011 were 5.8 million tons.
[Dagger] There are 53 sources with annual emissions greater than 1,000 tpy in nonattainment areas designated in 2013.
The EPA proposes that states be required to characterize air
quality around SO2 emission sources identified by the
thresholds presented in Option 1. The agency requests comment on the
proposed option, and the other options described and presented here.
Specifically, comment is requested on the emission threshold values (in
tpy), the 1 million CBSA population thresholds, their combination as a
means of determining how SO2 sources would be identified and
on any possible alternatives that might be appropriate for
consideration. The EPA requests comment on the scope of sources for
which we are requiring data through this proposed rulemaking. The EPA
is also interested in commenters' preferences and clear explanation of
the rationales for their positions. The EPA also requests any
information identifying sources that would be included by these options
but that have confirmed documentation to show that they will shut down
in the next several years. A number of sources included in the source
counts included in Table 1 have indicated their intent to shut down or
repower, meaning that the number of sources around which air agencies
would be directed to characterize air quality under this program is
likely overestimated for all options in Table 1. An updated and more
complete picture of which SO2 sources are scheduled for
modification or shutdown would be useful for refining the estimates in
Table 1 of the number of sources that would be covered under each
option.
IV. Data Requirements and Program Implementation Timeline
This section discusses the deadlines for air agency actions that
would be required under this proposed rule. It also discusses, for
informational purposes, additional anticipated implementation
milestones that are important in the SO2 designations and
implementation process. These deadlines and milestones were initially
suggested in the February 2013 SO2 Strategy Paper. In the
February 2013 SO2 Strategy Paper, the EPA also indicated its
intent to use these data (and any updated recommendations from the air
agency) to inform future designations in a timely manner. The EPA
believes that the implementation timeline proposed below is responsive
to concerns raised in comments on the May 2012 White Paper requesting
that air agencies have the flexibility and sufficient time to pursue
either the monitoring or modeling pathway for identified sources within
their jurisdiction. We also believe that this timeline represents a
practical but expeditious schedule for developing information needed to
determine SO2 air quality data for purposes of designations.
This schedule allows air agencies to account for SO2
reductions that will occur over the next several years as a result of
trends in industry and implementation of national and state level
programs. EPA solicits comments on the feasibility of the proposed
implementation timeline below.
------------------------------------------------------------------------
Date Action
------------------------------------------------------------------------
From promulgation of this From promulgation of this rulemaking
rulemaking to January 15, 2016. to January 15, 2016: Air agency and
the EPA Regional Office consult on
list of SO2 sources; air agency is
required to submit its list of
sources along with its election of
monitoring or modeling for
characterizing air quality to the
EPA Regional Administrator.
[[Page 27457]]
January 15, 2016.................. Air agency is required to submit
modeling protocols for sources that
will be characterized with
modeling.
July 2016......................... Annual Monitoring Network Plans due
to the EPA Regional Administrator
should include SO2 monitoring
network modifications intended to
satisfy the Data Requirements Rule.
January 1, 2017................... SO2 monitors intended to satisfy the
Data Requirements Rule are required
to be operational.
January 13, 2017.................. States electing to model are
required to provide modeling
analyses to the EPA Regional
Administrators.
August 2017....................... Expected date by which the EPA would
notify states of intended
designations.
December 2017..................... Intended date by which the EPA would
issue final designations for a
majority of the country.
August 2019....................... Anticipated due date for state
attainment plans for areas
designated nonattainment in 2017.
May 2020.......................... Required certification of 2019
monitoring data; states have the
opportunity to provide updated
state recommendations to the EPA
Regional Administrators.
August 2020....................... Expected date by which the EPA would
notify states of intended
designations for the remainder of
the country not yet designated.
December 2020..................... Intended date by which the EPA would
issue final designations for the
remainder of the country.
August 2022....................... Anticipated due date for state
attainment plans for areas
designated nonattainment in 2020.
------------------------------------------------------------------------
A. From Promulgation of This Rulemaking to January 15, 2016: Air Agency
and the EPA Regional Office Consult on List of SO2 Sources;
Air Agency Is Required To Submit Its List of Sources Along With Its
Election of Monitoring or Modeling for Characterizing Air Quality to
the EPA Regional Administrator
The EPA strongly encourages each air agency to consult with its EPA
Regional Office to identify sources exceeding the emission thresholds
in the final rule (as described in section III) and any other areas
near sources that do not exceed the emission thresholds but which would
be appropriate for air quality characterization as well. It will be
important for the air agency and the EPA to carry out this consultation
process as soon as possible and to reach agreement on the list of
sources quickly and efficiently.
As a starting point, the EPA has included in the docket to this
proposed rule a preliminary list of sources that appear to meet the
criteria described in the EPA's proposed source threshold approach.\29\
This list was developed based on the most recent publicly available
information found in national EPA databases, including the 2011 NEI as
well as the most recent data submitted in accordance with the EPA Acid
Rain Program and the Air Emissions Reporting Requirements (AERR)
rule.\30\ The EPA requests that air agencies provide in their comments
on this proposed rule any relevant updated information that would
support the addition or removal of a source area from this preliminary
list, along with relevant rationale and supporting information.
---------------------------------------------------------------------------
\29\ See EPA memorandum to the docket that identifies
SO2 emissions sources that would be covered by each
proposed source emissions threshold option, and sources located in
designated nonattainment areas.
\30\ Information on continuous emissions monitoring under the
Acid Rain Program can be found at: http://www.epa.gov/airmarkets/emissions/continuous-factsheet.html. Information on the AERR can be
found at: http://www.epa.gov/ttnchie1/aerr/.
---------------------------------------------------------------------------
Based on relevant information received during the comment period,
the EPA will update this preliminary list of source areas identified
for air quality characterization as warranted and issue a revised
version of the list at the time this rulemaking is finalized (currently
scheduled for late 2014). The EPA will also post the list on the EPA
SO2 designations Web site. We expect that in developing this
revised version of the list, data for calendar year 2013 would be the
most recently available information for EGU's subject to the Acid Rain
Trading Program. Emissions for these sources are recorded with CEMs and
the data for a particular calendar year are certified and publicly
available early in the following year.\31\ For non-EGUs, many of which
do not operate CEMs, SO2 emissions data for calendar year
2012 would be the most recently available data in late 2014.
---------------------------------------------------------------------------
\31\ See acid rain program emissions reporting requirements at
40 CFR part 75.
---------------------------------------------------------------------------
Section 51.1203(a) of this rulemaking, as proposed, would then
require each air agency to submit to its EPA Regional Administrator
\32\ by January 15, 2016, a final list identifying the specific sources
in the state around which SO2 air quality is to be
characterized, and whether the air agency commits to conduct monitoring
or modeling to characterize air quality around the source according to
the process defined in this rulemaking. We note that, while a state may
not have any sources that exceed the minimum source threshold
requirements, there may still be a separate need (such as may arise in
making future designations recommendations) for the air agency to
characterize air quality for any other sources below the thresholds in
this proposed rule that the air agency or the EPA Regional
Administrator deems may have the potential to violate the NAAQS. For
example, the air agency or the EPA Administrator may determine that the
air quality should be characterized around multiple sources located in
close proximity that individually are below the threshold but whose
combined emissions may violate the NAAQS.
---------------------------------------------------------------------------
\32\ As stated previously, the term ``EPA Regional
Administrator'' refers to the Regional Administrator or a delegated
representative.
---------------------------------------------------------------------------
We expect that meeting this submittal requirement could be
satisfied through a letter submitted to the EPA Regional Administrator.
By January 15, 2016, the EPA would expect that 2014 data would be
available for EGU sources and 2013 data would be available for non-EGU
sources. By considering the most recent emissions data, the air agency
and the EPA will be able to take into account any recent emissions
increases or decreases that would cause a source to be subject to the
requirements in this proposed rule or not.
The EPA believes that this proposed requirement for the air agency
to submit a list of source areas identified for further air quality
characterization, and the other data submittal requirements found in
sections 51.1203 of the proposed rule, are appropriate steps needed to
understand SO2 air quality throughout the country prior to
designations, and are consistent with section 110(a)(2)(B), section
110(a)(2)(K) and section 301(a)(1) of the CAA. Section 110(a)(2)(B)
indicates that state SIPs are to ``provide for establishment and
operation of appropriate devices, methods, systems, and procedures
necessary to (i) monitor, compile and analyze data on ambient air
quality and (ii) upon request, make such data available to the
Administrator.'' Section 110(a)(2)(K) states that SIPs shall ``provide
for (i) the performance of such air quality modeling as the
Administrator may prescribe for the purpose of predicting the effect on
ambient air quality of any emissions of
[[Page 27458]]
any air pollutant for which the Administrator has established a NAAQS
and (ii) the submission, upon request, of data related to such air
quality modeling to the Administrator.'' In this proposed rule, the EPA
is requiring air agencies to submit such SO2 monitoring and
modeling data, as requested. Lastly, section 301(a)(1) provides the EPA
with general authority to establish regulations as necessary to carry
out the agency's functions, which in this case includes ensuring the
attainment of the SO2 NAAQS throughout each state. This
section states that ``The Administrator is authorized to prescribe such
regulations as are necessary to carry out his functions under this
chapter. The Administrator may delegate to any officer or employee of
the EPA such of his powers and duties under this chapter, except the
making of regulations subject to section 7607(d) of this title, as he
may deem necessary or expedient.''
Since the process proposed in this rulemaking will lead to the
collection of additional air quality data to be used in the area
designations process, the EPA intends to make publicly available on the
EPA SO2 designations Web site the air agency submittals
required pursuant to this rule, any updated designation recommendations
from the air agency and any designation-related correspondence from the
EPA. Making this information readily available on the agency's Web site
would be consistent with what has been done for other NAAQS
designations processes.
We also are aware that due to a number of factors, there may be
sources in the power industry and other sectors that are in operation
as of January 15, 2016, but may be scheduled to shut down (e.g., due a
consent decree or other legal agreement) prior to January 2017 (when
the air agency should have ambient monitors operational and air quality
modeling completed). The EPA would expect that any applicable source
that intends to shut down but is still in operation on January 15,
2016, should be included on the air agency's list for SO2
air quality characterization. However, if by January 1, 2017, the air
agency can provide the EPA with a legal agreement or other detailed
information confirming that the source has permanently shut down, then
the air agency will have no further obligation regarding air quality
characterization for this source pursuant to this rulemaking.
B. January 15, 2016: Air Agency Is Required To Submit Modeling
Protocols for Sources That Will Be Characterized With Modeling
For source areas that the air agency identifies would be evaluated
through air quality modeling, the EPA proposes that an air agency must
also provide a modeling protocol to the EPA Regional Administrator by
January 15, 2016. The modeling protocol would include information about
such issues as the emissions input data, modeling domain, receptor
grid, meteorological data and how to account for background
concentrations. More details on the specific elements recommended to be
included in the modeling protocol can be found in section V.B.2 of this
proposed rule and in the draft modeling TAD,\33\ but air agencies also
have the option to use alternative elements on a case-by-case basis as
appropriate. The EPA Regional Office staff would be available to
consult with air agency officials to refine and agree upon the modeling
protocol for each relevant source. The EPA Regional Offices would
review the submitted information and follow-up with the states as
expeditiously as practicable, either approving the submitted
information in a similar manner to approval of annual monitoring plan
updates, or following-up with the states if adjustments to modeling
protocols are warranted.
---------------------------------------------------------------------------
\33\ The Draft SO2 NAAQS Designations Modeling
Technical Assistance Document can be found at http://www.epa.gov/airquality/sulfurdioxide/pdfs/SO2ModelingTAD.pdf.
---------------------------------------------------------------------------
C. July 2016: Annual Monitoring Network Plans Due to the EPA Regional
Administrator Should Include SO2 Monitoring Network Modifications
Intended To Satisfy the Data Requirements Rule
Under this proposed rule, air agencies may elect to characterize
air quality around some or all sources through ambient SO2
monitoring, using existing and new monitoring sites. The EPA proposes
that air agencies be required to submit relevant information about
these monitoring sites to the EPA Regional Administrator by July 1,
2016, as part of their annual monitoring network plan, in accordance
with the EPA's monitoring requirements specified in 40 CFR part 58. The
EPA anticipates that states electing to monitor to satisfy this
proposed rule will need to take explicit actions to identify, relocate
and/or install new ambient SO2 monitors that would
characterize peak, 1-hour SO2 concentrations in areas around
or impacted by identified SO2 sources. The EPA encourages
states to work with the EPA Regional Offices in the development of an
appropriate network plan to satisfy the intent of this rulemaking. In
the annual monitoring network plan, the EPA encourages states to
provide details on the adequacy of the SO2 network,
including rationale for why the proposed number of sites and their
individual locations are appropriate. Considerations for siting these
monitors are discussed in the draft monitoring TAD.\34\
---------------------------------------------------------------------------
\34\ The Draft SO2 NAAQS Designations Source-Oriented
Monitoring Technical Assistance Document can be found at http://www.epa.gov/airquality/sulfurdioxide/pdfs/SO2MonitoringTAD.pdf.
---------------------------------------------------------------------------
D. January 1, 2017: SO2 Monitors Intended To Satisfy the
Data Requirements Rule Are Required To Be Operational
The EPA proposes that air agencies that have chosen to characterize
air quality for certain SO2 sources through ambient
monitoring must have any relocated and/or new monitors operational by
January 1, 2017. Under this approach, it is anticipated that the first
3 years of data would be collected from 2017 through 2019, allowing the
first design value for each monitor to be calculated by May 2020. These
new monitoring data could then inform the air agency's designation
recommendation for the final round of designations (primarily for areas
for which air quality is characterized through ambient monitoring).
E. January 13, 2017: States Electing To Model Are Required To Provide
Modeling Analyses to the EPA Regional Administrators
The EPA proposes that air agencies choosing modeling to
characterize ambient air quality around identified SO2
sources be required to submit modeling analyses to the EPA Regional
Office by January 13, 2017, for all source areas they had previously
declared would be characterized through air quality modeling. These
modeling analyses should be conducted in accordance with the
recommendations in the EPA's modeling TAD or as otherwise approved on a
case-by-case basis. (Section V provides more information on the
technical details of these analyses.) The EPA believes that 2 years
from promulgation of the final rule is a reasonable amount of time for
air agencies to prepare the necessary data inputs and conduct such
modeling for all subject sources.
The EPA intends to conduct a second phase of designations during
2017, relying on modeling analyses and other related information and to
notify the
[[Page 27459]]
states of intended designations by August 2017. The EPA therefore
encourages states to submit with their modeling analyses updated
designation recommendations. In developing any updated designation
recommendations, the air agency should follow the EPA's most recent
SO2 designation guidance.\35\ We recommend that any such
updates to designation recommendations be submitted to the EPA Regional
Office at the same time the modeling analysis is due, by January 13,
2017.
---------------------------------------------------------------------------
\35\ The EPA issued guidance on the SO2 area
designations process on March 24, 2011. See: http://www.epa.gov/air/sulfurdioxide/pdfs/20110411so2designationsguidance.pdf. However, the
EPA may provide updated SO2 designations guidance, as
appropriate, in advance of the January 2017 submittal date.
---------------------------------------------------------------------------
The EPA Regional Office and the air agency should engage actively
in consultation to understand the inputs, assumptions and findings
associated with each air quality modeling analysis. The air agency
should submit thorough documentation of its modeling analysis and
should provide the EPA with supplemental information about the analysis
upon request, as the analysis will provide the basic technical
supporting information used by the EPA in developing the designation
for the area.
The EPA received a number of comments on the White Paper and in
subsequent policy discussions with stakeholders requesting that in the
next round of SO2 designations in 2017, the EPA should
designate areas as unclassifiable/attainment if it can be demonstrated
that such areas do not violate the SO2 NAAQS. Some
commenters provided examples of states having large areas with very few
SO2 sources, or no SO2 sources at all and
indicated that such areas would be candidates for an unclassifiable/
attainment designation.
The EPA finds merit in such examples and suggests that for this
next round of SO2 designations, the air agencies should
consider providing the EPA with any recommended boundaries and
supporting information for parts of their states for which they
recommend an ``unclassifiable/attainment'' designation (e.g., an area
without SO2 sources or that is not impacted by sources in
other areas). If the air agency recommends such a designation, the
boundary of the area would need to be developed carefully, keeping in
mind the fact that an additional set of source areas may be designated
3 years later based on monitoring data. Since the EPA expects to
designate the majority of the country in 2017, the only areas the EPA
would not be ready to take action on in 2017 are the areas for which
states have elected to install new monitors. The EPA's initial thinking
is that the state should not recommend a designation for any county
that includes a source area with new monitoring under way. The EPA
could designate as unclassifiable/attainment any area for which the
state has submitted sufficient appropriate modeling or monitoring data
to support such designation. The EPA may consider providing additional
designation boundary guidance, including guidance for areas without
sources, for this round of boundary recommendations at a later date.
In January 2017, there also may be undesignated areas with existing
ambient air quality monitors that have data for the most recent 3 years
(e.g., 2013-2015) that indicate a violation of the standard. The EPA
intends to designate any area that has newly monitored violations as
nonattainment in this next round of designations.
In other cases, air agencies may demonstrate that the existing
monitoring network suffices to evaluate the air quality status of
particular areas, such that monitoring data available by January 2017
are sufficient to justify designating the areas as attainment. For such
areas, the governors may wish to update their designation
recommendations and provide suggested boundaries for the areas, based
on their analysis of sources and source regions contributing to air
quality at the applicable monitor(s). Submittal of such recommendations
should be supplemented with a thorough network analysis as described in
the monitoring section of this rule, demonstrating that the network is
sufficient to assess peak concentrations in the area.
F. By August 2017: Expected Date by Which the EPA Would Notify States
of Intended Designations
Under CAA section 107(d)(1)(B)(ii), the EPA is authorized to
promulgate designations that differ from the designations recommended
by the state, but the EPA must notify the state of any such
modifications at least 120 days before promulgating modified
designations, providing the state an opportunity to provide further
input on the designations and boundaries for the affected areas. For
any areas being addressed in this round of designations, the EPA
intends to notify the states of intended designations by August 2017.
As with the previous SO2 designation process completed in
2013, these letters would indicate the EPA's intended designation and
boundary information for these areas and the states would have an
opportunity to provide comments and suggest modifications as
appropriate.
G. December 2017: Intended date by Which the EPA Would Issue Final
Designations for a Majority of the Country
Under the anticipated schedule, the EPA expects to finalize
designations by the end of 2017 for the following areas: (1) Those with
modeled violations, (2) any previously undesignated area with ambient
monitoring data from 2014-2016 indicating a violation, and (3) any
unclassifiable/attainment areas as appropriate. EPA anticipates that
this round of designations would address many areas across the country.
Areas that would not be designated at this time would include (but not
necessarily be limited to) those areas conducting new monitoring. For
purposes of further outlining the timeline for submitting attainment
plans and demonstrations, we will assume there will be a 60-day period
between publication of the final designations in the Federal Register
and the effective date of the designations, meaning that new
nonattainment designations are anticipated to become effective in
February 2018.
H. August 2019: Anticipated Due Date for State Attainment Plans for
Areas Designated Nonattainment in 2017
Areas that are newly designated as nonattainment would have a new
SIP obligation due 18 months from the effective date of the
designation.\36\ Thus, areas with an effective date of designation in
February 2018 would have attainment SIPs due in August 2019. These
plans would need to demonstrate how the area would attain the standard
as expeditiously as practicable, but no later than 5 years from the
effective date of the designation, or by February 2023.\37\
---------------------------------------------------------------------------
\36\ SO2 SIPs are due within 18 months, per CAA
section 191(a).
\37\ The attainment date for SO2 nonattainment areas
is as expeditiously as practicable, but not later than 5 years from
the date of designation, per CAA section 192(a). The SO2
implementation guidance can be found at: http://www.epa.gov/oaqps001/sulfurdioxide/implement.html.
---------------------------------------------------------------------------
I. May 2020: Required Certification of 2019 Monitoring Data; States
Have the Opportunity To Provide Updated State Recommendations to the
EPA Regional Administrators
As noted in paragraph D above, air agencies electing to use
monitoring to satisfy this data requirements rule will be required to
have relocated and/or new monitors operational by January 1, 2017. In
early 2020, the air agency
[[Page 27460]]
would be able to certify data collected during 2019, thereby providing
a complete, quality-assured data set for 2017-2019 for each ambient
monitor.
In this scenario, in the event that the new monitoring data result
in changes to designation recommendations previously submitted, the
state would also have the opportunity to submit revised designation and
boundary recommendations to the EPA by May 1, 2020, for all parts of
the state that have not yet been designated. The EPA expects that the
state would recommend nonattainment boundaries that include any nearby
contributing sources, in the same manner as discussed in the EPA's
SO2 designations guidance. Presumably, at the completion of
this round of the designations process, any areas not designated as
nonattainment would be designated as unclassifiable/attainment.
J. August 2020: Expected Date by Which the EPA Would Notify States of
Intended Designations for the Remainder of the Country Not Yet
Designated
As noted above, CAA section 107(d)(1)(B)(ii) authorizes the EPA to
promulgate designations that differ from the designations recommended
by the state but requires the EPA to notify the state of any such
modifications at least 120 days before promulgating modified
designations. For the areas identified in paragraph I above, the EPA
expects to notify the states of intended designations in August 2020.
The letters would include the EPA's intended designation and boundary
information for these areas and the states would have the opportunity
to provide comments and suggest modifications as appropriate.
K. December 2020: Intended Date by Which the EPA Would Issue Final
Designations for the Remainder of the Country
Under its anticipated designations schedule, the EPA would finalize
designations for the remaining undesignated areas in each state in the
December 2020 time frame. The timeline below for submitting attainment
plans and demonstrations assumes there will be a 60-day period between
publication of the final designations in the Federal Register and the
effective date of the designations, meaning that any new nonattainment
designations are anticipated to become effective in February 2021.
L. August 2022: Anticipated Due Date for State Attainment Plans for
Areas Designated Nonattainment in 2020
Areas that are newly designated as nonattainment would have a new
SIP obligation due 18 months from the effective date of the
designation.\38\ Thus, nonattainment areas with an effective date in
February 2021 would have attainment SIPs due in August 2022. These
plans would need to demonstrate how the area would attain the standard
as expeditiously as practicable, but not later than 5 years from the
effective date of the designation, or by February 2026.\39\
---------------------------------------------------------------------------
\38\ SO2 SIPs are due within 18 months of area
designation per CAA section 191(a).
\39\ The attainment date for SO2 nonattainment areas
is as expeditiously as practicable, but not later than 5 years from
the date of designation, per CAA section 192(a).
---------------------------------------------------------------------------
V. Technical Considerations
Section III of this preamble presents detailed discussion of the
threshold-based air quality characterization approach that will focus
limited resources most efficiently to implement the SO2
NAAQS in areas that contain sources with larger SO2
emissions and higher numbers of people, in order to address areas where
there may be higher potential for NAAQS violations that adversely
affect public health. This section discusses the different
opportunities air agencies may use to provide the necessary air quality
information to the EPA for areas around those identified sources. Based
on this information, the EPA proposes taking an approach that allows
for the use of air quality monitoring or modeling information, or a
combination of both, for designations.
An approach using monitoring or modeling for designations actions
would be consistent with the EPA's historic practices for
SO2 NAAQS implementation, where both monitoring and modeling
have been used as appropriate in the designations process. Air agencies
would have the flexibility to assess whether their SO2
sources above the thresholds are violating the SO2 NAAQS by
employing either ambient air quality monitoring or air quality
modeling. An air agency would not be limited to employ only one method
within its jurisdiction.
When considering whether monitoring or modeling may be most
appropriate for the area around each identified source, air agencies
are encouraged to consider a number of factors. One key factor is
whether or not the location or characteristics of an identified source
or facility are conducive to modeling. The EPA strongly encourages air
agencies to consider using monitoring to characterize air quality near
those sources that are not easily characterized through dispersion
modeling. Sources that may not be easily characterized through
dispersion modeling include a source situated in an area of complex
terrain and/or situated in a complex meteorological regime and areas
that have multiple, relatively small sources with overlapping plumes.
States would need to consider each area around a source on a case-
by-case basis to determine whether the modeling or monitoring pathway
is most appropriate for characterizing air quality around that source.
For areas with multiple sources that a state could recommend be
included in a common area, the EPA suggests that a common analytical
approach for assessing air quality be followed for all of the sources
in the common area. For situations where multiple sources are located
in proximity across state boundaries, the EPA recommends that the
relevant air agencies work together to determine a common analytical
approach for assessing air quality in that area. In these types of
situations, it would not be appropriate to choose monitoring for some
sources and modeling for others, since under this proposed rule areas
with sources using these pathways would be designated on different time
frames. In general, however, the determination of whether to use
monitoring or modeling to characterize air quality around a source
should be done on a case-by-case basis.
To assist states in the implementation of this rulemaking, the EPA
has produced draft, non-binding technical assistance documents that
discuss options and suggested approaches, and methods on how monitoring
or modeling efforts to characterize air quality around an identified
source might be conducted. The monitoring TAD provides potential
options and recommendations on different approaches that can be used to
site source-oriented SO2 monitors in locations of expected
maximum 1-hour concentrations. Modeling is generally a less costly and
less resource intensive option for providing reliable information for
use in designations. In addition, refined dispersion models are able to
characterize SO2 air quality impacts from the modeled
sources across the domain of interest on an hourly basis with a high
degree of spatial resolution. The modeling TAD provides recommendations
for states planning to model source areas in their state.
[[Page 27461]]
A. Monitoring
States that identify monitoring as the pathway to assess air
quality around a particular SO2 source would have the option
to identify, relocate and/or install new monitors around the source by
January 1, 2017, to provide data for use in designations in 2020. These
monitors are expected to be source-oriented and sited to characterize
location(s) of expected maximum 1-hour concentrations.
The monitoring TAD provides different approaches describing how
source-oriented monitoring networks might be designed or augmented. The
TAD discusses information that would be most useful to collect at the
outset of formulating or evaluating a source-oriented network design,
with an eye toward identifying sites at which maximum 1-hour
concentrations can be expected. Examples include considering data about
the source itself (emissions rate info, CEM data, stack height, stack
temperature, permit requirements, control technology, etc.); similar
information about any nearby SO2 sources; existing air
quality data from any nearby ambient monitors; any existing modeling
data for the source, such as from past prevention of significant
deterioration permits revision; meteorological data; and information
about the local geographic setting of the source and surrounding area.
The TAD presents options on using this information to feed into one or
more siting approaches, including modeling, exploratory monitoring, or
other analysis, such as a ``weight of evidence'' approach, to inform an
appropriate monitoring network design to characterize the air quality
around an identified SO2 source.
As noted above, the EPA estimates that up to a third of the
existing SO2 monitoring network (as of 2013) may be
considered to be source-oriented and/or characterizing maximum
concentrations. The agency recognizes that using and leveraging
existing infrastructure is a logical consideration in developing a
network design and, in some cases, there may be a limited number of
existing monitors appropriately situated in a way that might satisfy
this rule. Air agencies that choose to identify, relocate, or install
new monitors in an effort to satisfy this rule may use these monitors
to satisfy the existing PWEI minimum monitoring requirements
(promulgated in the 2010 SO2 NAAQS revision [40 CFR part 58,
Appendix D, Section 4.4.2]), if applicable to an area. However, those
existing monitors currently in use to satisfy the PWEI-induced minimum
monitoring requirements are not automatically eligible to satisfy the
data requirements rule, as they may not be appropriately sited (e.g.,
they might not be source-oriented, maximum concentration sites). The
EPA notes that PWEI monitors and other existing monitors (both
regulatory and non-regulatory) may be helpful in providing information
to help states determine appropriate locations for relocated or new
monitors.
As discussed in section IV, this rulemaking proposes that in
January 2016, states will submit to their EPA Regional Administrator
the list of sources for which they will collect additional information
for initial designations. This list would include all the sources that
are above the annual emissions threshold that is ultimately finalized,
as well as those sources that either the state or the EPA Regional
Administrator has also identified as needing additional information on
local air quality. As discussed above, the state would also commit at
that time to the particular pathway (monitoring or modeling) it would
employ to characterize air quality around each source. The EPA believes
that the proposed requirement for the air agency to submit a list of
sources identified for further air quality characterization, and the
other associated data submittal requirements found in sections 51.1203
of the proposed rule, are appropriate steps needed to characterize
SO2 air quality throughout the country prior to
designations, and are consistent with section 110(a)(2)(B) and section
110(a)(2)(K) of the CAA.
This rulemaking also proposes that in their annual monitoring
network plans submitted in July 2016, air agencies must identify the
new monitoring sites they have elected to deploy to assess air quality
around selected sources to satisfy this data requirements rule. The EPA
expects that states would provide analyses supporting the network
design approach to characterize air quality around each relevant source
(i.e., number of monitors for each SO2 source, information
demonstrating that the monitors would be placed in the area/areas of
maximum concentrations, etc.). The EPA proposes that any relocated or
new monitors must be installed and operational by January 1, 2017, and,
thus, allowing for data collection during the 2017-2019 timeframe and
for use of these data for designations expected in 2020. The EPA also
proposes to require that any relocated or new monitors be operated in a
manner equivalent to those monitors operated elsewhere in the State and
Local Air Monitoring Stations (SLAMS) network; they do not, however,
have to be designated as SLAMS. Specifically, the monitors should use
Federal Reference Methods (FRMs) or Federal Equivalent Methods and meet
the requirements of 40 CFR part 58 Appendices A, C and E. Further, the
resulting data should be reported to the Air Quality System (AQS) and
would be subject to annual data reporting and certification
requirements listed in 40 CFR parts 58.15 and 58.16. When the data are
reported to AQS, the data will be available to the public through this
system.
The EPA recognizes that in some cases the deployment of a
monitoring site might be delayed for a short period of time due to
certain factors not directly under the air agency's control (e.g.,
obtaining permits or access to power for the site) and could cause the
air agency to miss the January 1, 2017 deadline. In the event that a
state has chosen the monitoring pathway for air quality assessment for
a particular source and it does not have the monitor(s) installed and
operational by the January 1, 2017, deadline such that the monitor
would not have complete data for the first quarter, this would be a
reason for concern for the EPA because the state would not be in a
position to collect 3 complete calendar years of monitoring data (2017-
19) as would be required for all other new monitoring sites established
by other states pursuant to this rulemaking.\40\ In those situations
where it is evident that sufficient and appropriate monitoring will not
be conducted in a timely manner, the EPA proposes that the source would
be ``moved'' to the modeling pathway and would be included in the
designations process intended to be conducted in 2017, based on
appropriate information the EPA has obtained at that time. In this
situation, if the state fails to provide modeling information for the
source, the EPA would make decisions for designations based on the
modeling and monitoring information available to the EPA at the time of
designations. Therefore, the EPA strongly encourages states to only
choose the monitoring option for a source if the state is confident in
its ability to install and begin operation of any new monitors in a
timely manner and to follow through with continued operation of the
monitoring network as required by this rulemaking. The EPA requests
comment on the approach proposed above. The EPA also requests
[[Page 27462]]
comments on any alternative approaches that could most effectively
address a situation where an air agency is acting in good faith to
deploy monitors on time but experiences a delay outside of its control.
---------------------------------------------------------------------------
\40\ Data completeness requirements for the 1-hour
SO2 NAAQS are described in 40 CFR part 50, Appendix T. A
quarter is considered to have complete data when at least 75 percent
of the sampling days have complete data.
---------------------------------------------------------------------------
The potential use of third party SO2 monitors was raised
in past stakeholder discussions. In some cases, there may be industrial
or other stakeholder monitoring sites in operation in an area around a
source that a state chooses to monitor. If one or more of those sites
is determined to be in an appropriate location to characterize peak 1-
hour concentrations around the identified source, there is potential
for such monitors to be leveraged to satisfy the requirements in this
rule.\41\ The use of such monitors, including details on how the
monitors and monitoring data would be ensured to meet quality assurance
and other criteria in 40 CFR part 58 Appendices A, C and E, would need
to be documented and included in the annual monitoring network plan
submitted to the EPA in July 2016. The EPA encourages air agencies to
engage other stakeholders to pursue ambient monitoring partnerships
wherever possible to use existing infrastructure, increase
communication among parties and use available resources as efficiently
as possible.
---------------------------------------------------------------------------
\41\ Monitors operated by third parties have been used for
certain regulatory purposes in the past, provided they met certain
quality assurance and oversight requirements.
---------------------------------------------------------------------------
In other cases, air agencies may have limited budgets which would
not allow for the funding of additional monitors, but affected sources
may wish to fund the deployment of additional monitors as indicated in
comments previously received on the White Paper. Any new monitoring
sites funded by the regulated community also would need to be operated
in manner equivalent to SLAMS, meeting quality assurance and other
criteria in 40 CFR part 58 Appendices A, C and E, subject to data
reporting and certification requirements, and there would need to meet
applicable requirements for continued operation into the future if
ambient concentrations exceed NAAQS levels. These sites would need to
be documented and included in the annual monitoring network plan
submitted to the EPA in July 2016.
In comments on the 2012 White Paper and on the 2013 draft
monitoring TAD, the EPA received feedback from states and industry to
consider a pathway to allow the shut-down of monitors operated to
satisfy this proposed rule if no NAAQS violations are discovered.
Specifically, due to current state and local resource constraints and
in consideration of the potential collaboration that could occur
between states and industry to operate some source-oriented
SO2 monitoring sites, commenters suggested that monitoring
operations should be allowed to cease if no NAAQS violations are found.
As proposed, states electing to monitor around identified
SO2 facilities would be expected to have SO2
monitors that are intended to satisfy this proposed rule to be
operational by January 1, 2017. In a majority of those cases, the EPA
believes that states will have to install new monitors, relocate
existing monitors and/or work with industry to install new monitors or
leverage existing industrially operated SO2 monitors to
satisfy the data requirements rule. In any case, the monitors operated
to satisfy this proposed rule would be expected to have 3 years of
complete data (spanning 2017 through 2019) available for design value
calculations in early 2020.
In consideration of recent feedback received on this issue in
comments on the monitoring TAD and SO2 White Paper, the EPA
is proposing that a monitor that has been deployed pursuant to this
rule and is located in an area that is designated attainment in the
anticipated third round of initial designations in 2020 may be eligible
for shutdown provided the monitor meets certain criteria. Any
SO2 monitor identified in an approved state annual
monitoring network plan to satisfy this proposed data requirements rule
may be eligible for shut-down in 2021 or later if the following
criteria are met: (1) The monitor is not also satisfying other minimum
SO2 monitoring requirements listed in 40 CFR part 58
Appendix D; (2) the monitor is not otherwise required to meet
requirements in a SIP or permit; and (3) the monitor has recorded a 3-
year design value that is no greater than 50 percent of the 1-hour
SO2 NAAQS. The EPA also proposes that any SO2
monitor eligible for shutting down would need to be approved by the EPA
Regional Administrator before monitoring operations could cease. This
policy is similar to the provision allowing the EPA Regional
Administrators to waive Lead NAAQS monitoring requirements if data
indicate that the design value of the lead monitor has not exceeded 50
percent of the Lead NAAQS, as listed in 40 CFR part 58 Appendix D,
Section 4.5(ii). The EPA proposes the 50 percent criterion for
SO2 monitors because such a precedent was established in the
lead monitoring regulations and because SO2 is a ``source-
oriented'' pollutant similar to lead. As an alternative, the EPA is
also proposing an option in which the same criteria noted above would
need to be met, except that the monitor would be eligible to cease
operations if it recorded a design value in 2018-2020 or a later 3-year
period that is no greater than 80 percent of the 1-hour SO2
NAAQS. This 80 percent criterion is indirectly derived from existing
language in 40 CFR part 58.14(c)(1) describing one of several pathways
to for states to shutdown existing SLAMS monitors, and it was also a
criterion suggested by a state air agency in comments on the monitoring
TAD. The EPA requests comment on the two proposed options for design
value criteria for SO2 monitor shutdowns, as well as other
values within the 50-80 percent range. EPA requests that commenters
provide specific technical rationale supporting any approach they
recommend.
The EPA proposes these options to cease monitor operations in
response to stakeholder concerns, but also believes it is important for
air agencies to assess whether, even after monitoring data indicate low
ambient SO2 concentrations, the areas around these sources
that are required to be characterized under this rulemaking continue to
attain the standard in the future. To address this need, the EPA
proposes that the air agency be required to assess SO2
emissions changes annually, beginning in the year after the monitor
ceases operation. Emissions data for large SO2 sources would
be available from annual reporting required for various emissions
trading programs, the AERR rule, and other regulations. The AERR rule
requires states to report SO2 emissions data annually for
large SO2 sources. Every 3 years states must report data on
SO2 sources with potential to emit more than 100 tons per
year. In other years, the AERR rule requires states to report data on
SO2 sources with potential to emit more than 2,500 tons per
year. In addition, under the Acid Rain Program and other emission
trading programs, many large combustion sources of SO2 are
required to continuously measure and record emissions of
SO2. These sources report hourly emissions data to the EPA
on a quarterly basis. These requirements would be expected to cover the
vast majority of sources subject to the SO2 data
requirements rule. States would need to work with any other source not
subject to an annual SO2 emissions reporting requirement
under existing regulations to ensure that annual SO2
emissions can be reported for the source under this data requirements
rule. For areas around these sources in which total SO2
emissions increase over the
[[Page 27463]]
emissions for the previous year, the air agency would be required to
submit to the EPA an assessment of the cause of the increase and
provide an initial determination of whether or not the air quality
around that source should be further re-assessed. The air agency could
choose to reinstate the operation of the air monitor or complete air
quality modeling for the source area to verify that the area continues
to attain the standard. Factors that the air agency should consider in
making this determination include: The magnitude of the emissions
increase and information about changes in the emissions profile, hourly
emission rate, or operating schedule of the source.
The EPA proposes two options for how the air agency would submit
this report and how the EPA would review and act on it. Under the first
procedural option, we propose that the air agency would submit a report
to the EPA annually as an appendix to the air agency's annual
monitoring plan. The annual monitoring plan is required to be submitted
to the EPA Regional Administrator by July 1 each year. A primary
objective of this approach would be to enable the air agency to save
time and resources by providing a single process for the public review
and opportunity for comment on the annual monitoring plan and annual
reports to demonstrate ongoing attainment of previously monitored
areas.
The inclusion of this verification report as an appendix to the
annual monitoring plan would ensure that the report would be subject to
the same opportunities for public review and comment that are to be
provided for the monitoring plan pursuant to regulations at 40 CFR part
58.10. Those regulations specify that if the air agency modifies the
monitoring plan from the previous year, then prior to taking final
action to approve or disapprove the plan, the EPA would be required to
provide an opportunity for public comment on its proposed action. The
public would have the opportunity to comment on any plan by the state
to cease operation of an existing monitor or to add any new monitor to
the network. In addition, the public would also have the opportunity to
comment on the state's annual report of emissions data for sources for
which the state ceased the operation of nearby monitors. The
regulations also indicate that if the state has already provided a
public comment opportunity in developing its revised monitoring plan
and has made no further changes to the plan after reviewing public
comments that were received, then it could submit the public comments
along with the revised plan to the EPA and the Regional Administrator
would not need to provide a separate opportunity for comment before
approving or disapproving the plan.
Under the second procedural option, the annual report of emissions
data for sources for which the state ceased the operation of nearby
monitors would not be submitted to the EPA as an appendix to the annual
monitoring network plan. Instead, it would take the form of a separate,
independent annual submittal from the state to the EPA Regional
Administrator. However, we propose that this report would be due by the
same July 1 date each year. This independent submittal would follow the
general guidelines set forth in 40 CFR 58.10 regarding opportunities
for public review and comment as described in Option 1 above, but the
report would only include the annual assessments associated with
sources in areas that were designated unclassifiable/attainment and for
which the EPA granted approval to cease monitoring. The public would
have the opportunity to comment on each report when it is submitted
annually.
The EPA believes that the main advantage of the first option is
that from a procedural standpoint, it would leverage the time and
resources that are already devoted to the existing annual monitoring
plan development and public review process. In contrast, the second
option would require additional state and the EPA resources to provide
for public review opportunities in parallel with the monitoring plan
process. Regardless of which procedural approach is included in the
final rule, we believe that it will be important for the EPA to
communicate to each state the reasoning behind any action or decision
the EPA makes with regard to the submitted ongoing verification of
attainment report. This information should be provided in writing in a
letter or Federal Register document, as appropriate.
The EPA solicits comments on the merits of the proposed monitor
shutdown policy and the use of 50-80 percent of the NAAQS as a
criterion for shut-down eligibility. The EPA also solicits comments on
preferences regarding the approach for ongoing assessment of air
quality after a monitor is shutdown either as an appendix to the annual
monitoring network plan or as a separate document, as the means by
which air agencies provide information to the EPA Regional Office. The
EPA requests any suggested alternatives to these procedural options.
B. Modeling
This section explains how modeling should be conducted and
submitted to the EPA for those sources for which a state chooses to
characterize ambient SO2 air quality conditions using air
quality modeling. While the basic modeling tools to be used to assess
air quality around these sources are the same tools often used for
other modeling exercises, such as attainment demonstrations or
permitting of new/modified sources, this rule and the associated
modeling TAD describe significant differences in the way these modeling
tools should be used that are unique to the area designations
process.\42\ When modeling to assess SO2 air quality for the
area designations process, it is appropriate to characterize actual air
quality and it is not necessary to project potential air quality.
Modeling conducted for the purposes of designations in effect is used
as a surrogate for ambient monitoring of current actual air quality.
Therefore, when modeling is used for SO2 designations, the
inputs to the models may be designed to more accurately represent
actual air quality.
---------------------------------------------------------------------------
\42\ Air quality modeling that is conducted to demonstrate
attainment for a nonattainment area or to project potential air
quality impacts for the permitting of a new or modified source
commonly uses allowable or permitted emissions levels rather than
actual emissions levels.
---------------------------------------------------------------------------
The EPA anticipates that states would use AERMOD to conduct this
designations modeling, as AERMOD is the EPA's preferred near-field
dispersion model and has been demonstrated to be a reliable predictor
of SO2 air quality given appropriate input data. As part of
its development, AERMOD was evaluated using 17 field studies, several
of which involved short-term measurements of SO2, robust
site-specific meteorology and accurate measurements of emissions. The
EPA is confident that AERMOD can provide accurate predictions of actual
SO2 concentrations, given representative meteorology and
accurate emissions inputs.
1. Inputs for Designations Modeling
There are 3 air quality modeling inputs used for designations
modeling that would differ from the permit and implementation plan
modeling requirements set forth in Appendix W of 40 CFR part 51. As
noted above, the objective of this designations modeling approach is to
assess actual, current air quality. The 3 modeling inputs that are
required to reflect actual air quality are: emissions data, stack
height and years of meteorological data.
[[Page 27464]]
(a) Emissions--General Issues
Dispersion modeling has typically been used to estimate the ambient
impact of a source's allowable emissions for use in attainment
demonstrations or in setting emission limits. In these situations, it
is important to consider the full potential a source has to emit the
relevant pollutant(s). In contrast, for the designations process it is
important to understand what a source is actually emitting, or has
actually emitted in the recent past. Traditionally, to characterize air
quality for the designations process for other NAAQS pollutants, the
EPA has exclusively used data from air quality monitoring networks.
However, as noted above, due to the fact that SO2
concentrations can vary substantially with distance and direction away
from the source, given the limitations in the existing monitoring
network in identifying peak SO2 concentrations and given
that modeling data has already been employed for past designations for
the SO2 NAAQS, the EPA believes that dispersion modeling is
an appropriate option for representing current (or recent)
SO2 air quality.
Traditionally, when modeling is used for estimating future air
quality, a source's allowable emission limits are used in the modeling
application to assess whether the potential emissions from the source
might cause violations. For designations, the EPA believes it is
appropriate to use current actual emissions to obtain estimates of
current actual air quality. Specifically, the EPA recommends that the
air agency should use a source's most recent 3 years of actual
emissions in the modeling analysis to estimate air quality for that 3-
year period. There are a range of recommended options for determining
these actual emissions which are discussed in the modeling TAD. While
actual emissions would be the preferred choice to use for emissions
inputs, states have the option of using a more conservative approach by
inputting a source's most recent 3 years of allowable, or ``potential
to emit,'' emissions. Further discussion below describes situations in
which states may prefer to use allowable emissions in this analysis.
Additional information and recommendations on this approach are
discussed in the modeling TAD.
In addition to considering actual emissions from the principal
source or sources in an area, the modeling analysis needs to take into
consideration the relevant SO2 ``background'' concentration
for the area. When modeling is intended to assess current air quality
(such as modeling for the designations process), the modeling also
needs to consider the background concentrations of SO2. The
inclusion of ambient background concentrations to the model results is
important in determining the modeled cumulative impacts of all nearby
sources. In an area with an air quality monitor, the SO2
concentrations recorded by the monitor might reflect the combination of
local source impacts and any other ``background'' contribution to
SO2 concentrations from other sources. The inclusion of
ambient background concentrations to the model results is important in
determining the modeled cumulative impacts of all nearby sources. Thus,
ambient background concentrations are determined on a case-by-case
basis, depending on factors such as the proximity of other
SO2 sources to the source being modeled, and the distance
and location of the closest ambient monitor to the source or sources
being modeled. Please see the modeling TAD for additional suggestions
on identifying background concentrations to be incorporated into this
modeling.\43\
---------------------------------------------------------------------------
\43\ The Draft SO2 NAAQS Designations Modeling
Technical Assistance Document can be found at http://www.epa.gov/airquality/sulfurdioxide/pdfs/SO2ModelingTAD.pdf.
---------------------------------------------------------------------------
(b) Emissions--Accounting for Recent Emission Reductions in Modeling
Analyses
The EPA seeks to provide an incentive to states to work with
sources to install controls and reduce emissions prior to final
designation in 2017. The EPA expects that in some cases, air quality
modeling conducted well in advance of January 2017 may indicate a
violation of the 1-hour SO2 standard in some areas. To
address such situations and potentially avoid a nonattainment
designation, the air agency may wish to consult with the source and
conduct additional analyses with the source to identify a control
measure or an emission limit that would ensure attainment with the 1-
hour SO2 standard for the area around the source. The air
agency could then take action to adopt enforceable emissions
limitations as necessary prior to January 2017 and conduct modeling
analyses based on these new emissions limits as explained below.
The EPA expects that a number of emissions sources may be
candidates for this optional approach. Many EGUs will need to meet
compliance deadlines for the Mercury and Air Toxics Standards (MATS) in
2015-2016 and EPA expects that many will become subject to Title V
permits that require compliance with MATS SO2 emission
limits as the means of demonstrating compliance with the MATS
requirements related to acid gas emissions. These EGUs may be able to
adopt control technologies and enforceable emission limits to reduce
emissions of SO2 as well as mercury. Similarly, industrial
boiler operators will have the incentive to adopt SO2
emission limits as part of their strategy for complying with the
Industrial Boiler Maximum Achievable Control Technology Standard.
As long as these controls are implemented and enforceable as of
January 2017, the EPA believes it would be appropriate for the new
lower allowable emission limit to be used in a modeling analysis in
place of the old, higher, actual data from the last 3 years. The air
quality impacts from such a source would, at worst, be characterized by
the new enforceable allowable limit and could be used as a basis for
future designations. Thus, for the purposes of meeting the data
requirements rule where a source has adopted new enforceable emission
limits, the state may use these new allowable emission limits when
completing their modeling analyses due in January 2017. Instead of
using the most recent 3 years of actual emissions data or previously
allowable emissions limits, the air agency could use the new emissions
information as the inputs for all 3 years of their designations
modeling.
This approach allows additional time in 2015 and 2016 for the
sources to reduce their emissions and if the state is able to
demonstrate attainment with the new controls or emission limits, the
governor of the state has the opportunity to modify its designation
recommendation accordingly. The EPA notes that this option to model
recently adopted emissions limits to avoid a nonattainment designation
provides an incentive for the air agency and facility to achieve
emissions reductions that will result in health benefits sooner in the
communities located near these sources (since local air quality would
improve sooner than if the area were designated nonattainment in 2017
and attainment were required by no later than 2022).
(c) Stack Height
Air quality modeling that is used for projecting future air quality
when setting emission limits must use ``good engineering practice''
(GEP)\44\ stack height in order to not allow inappropriate credit in
SIPs and federal implementation plans for techniques
[[Page 27465]]
that disperse rather than reduce or eliminate emissions, as required by
CAA section 123 and the EPA's stack height rules.\45\ This approach
helps ensure the attainment of the NAAQS with the use of these emission
limits.
---------------------------------------------------------------------------
\44\ For a complete definition of GEP stack height, see 40 CFR
51.100(ii).
\45\ See stack height regulations at 40 CFR 51.100(ff)-(kk); and
40 CFR 51.118.
---------------------------------------------------------------------------
As noted previously, the modeling approach described in this
proposed rule for initial area designations is to be used for assessing
actual air quality rather than for the development of future emissions
limitations. Accordingly, it is more appropriate to use actual stack
height in conjunction with actual emissions when using a modeling
approach to characterize current air quality. The concern about giving
inappropriate credit for dispersion techniques is not relevant in this
situation as section 123 applies only to emission limitation controls.
This situation is unique for these initial SO2 designations
because states would be assessing actual air quality and this is
different from the situations subject to section 123 requirements,
where GEP stack height is traditionally used to determine what emission
limits are needed to ensure future attainment of a NAAQS. The
combination of actual stack height with actual emissions would more
effectively characterize the current air quality around a source.
As discussed in the previous section, there may be certain sources
that states wish to model using allowable emissions. If a state chooses
to use allowable emissions, then it should also use GEP stack height
when the actual stack height exceeds the GEP height. In situations
where the actual stack height exceeds the GEP height, the GEP stack
height is more appropriate because the GEP height is used when
calculating the allowable emission rates and using actual stack height
in such a case would not reflect the true allowable emissions for the
source. Stacks with actual stack heights below the GEP height would use
the actual stack height because GEP stack height would not have been a
relevant factor in determining the source's prior emissions limit, and
use of GEP stack height in this case would not accurately reflect
actual ambient impacts. Additional recommendations on the use of actual
stack height can be found in the modeling TAD.
(d) Meteorological Data
In accordance with 40 CFR part 51, Appendix W, air agencies and
sources conducting SO2 modeling for permitting or SIP
attainment demonstrations generally use either 5 years of National
Weather Service meteorological data, or 1 year of on-site
meteorological data. These data need to be representative of the area's
meteorology, but do not necessarily need to be from the most recent
years of data. In contrast, the modeling approach discussed in this
proposed rule uses alternate meteorological inputs to characterize
current air quality. For purposes of conducting modeling that better
simulates what might be expected to be measured by an ambient monitor,
this rule proposes the use of 3 years of meteorological data. Ideally,
air agencies would use the most recent 3 years of meteorological data
and the same 3 years of actual emissions data when modeling for
designations. The modeling TAD has additional suggestions on these
meteorological inputs.
2. Modeling Protocols and Analyses
As discussed previously, this rulemaking proposes that each state
submit to its EPA Regional Administrator by January 15, 2016, a list
identifying the sources for which it will characterize nearby air
quality and the analytical approach (monitoring or modeling) to be used
for each source. This list should include all sources in the state that
are above the relevant emissions thresholds and those additional
sources that either the state or the EPA Regional Administrator has
also identified as needing additional information on local air quality.
In preparation for conducting modeling, the state would need to
develop a modeling protocol for all the sources the state plans to
model. This protocol can be source specific, or in some cases, the
state may propose a standard protocol for all the sources in its state.
Details on the suggested protocol elements and the recommended standard
format of this protocol can be found in the modeling TAD. The state
would submit this protocol to the Regional Administrator for review at
the same time it submits its list of sources outlining its monitoring
and modeling choices. The state is encouraged to work with its EPA
Regional Office throughout 2015 while developing its modeling
protocols.
3. State Recommendations for 2017
Under this rule, air agencies would be required to submit modeling
analyses for selected source areas by January 13, 2017, and at the same
time air agencies could submit revised designation and boundary
recommendations for these areas based on these new modeling data. These
recommendations could include modeling demonstrating that the source
area is either attaining or violating the current SO2
standard.
States could also assess recent data from their existing
SO2 monitoring networks and provide designations
recommendations based on these data as well. If they have properly
sited source-oriented monitors that are attaining the current
SO2 NAAQS with 3 years of quality assured data, they could
submit a demonstration showing that those monitors are properly sited
(following the suggested guidelines in the monitoring TAD), along with
a recommendation for a designation of unclassifiable/attainment for the
associated area. Likewise, if the state has an existing monitor that is
violating the standard and the area has not yet been designated
nonattainment, it should provide a nonattainment area boundary
recommendation for the associated area at this time. Lastly, the state
may wish to submit revised boundary recommendations for areas with low
emissions that do not contain any sources above the threshold, or for
areas with additional sources identified by the state or Regional
Administrators for further characterization.
Thus, since the EPA expects to designate the majority of the
country in 2017, the only areas the EPA would not be ready to take
action on in 2017 are the areas for which states have elected to
install new monitors. The EPA's initial thinking is that the state
should not recommend a designation for any county that includes a
source area with new monitoring under way. The EPA may consider
providing additional designation boundary guidance for this round of
boundary recommendations at a later date.
4. Ongoing Air Quality Characterization Requirements for Areas
Designated Attainment Based on Modeling
Typically, in situations where ambient monitoring data alone are
used to assess air quality to determine whether an area is attaining
the NAAQS, these monitoring data continue to be collected by the air
agency, made publicly available and used for a variety of regulatory
and non-regulatory purposes. Ambient monitoring is commonly continued
to verify ongoing maintenance of the standard, both for areas that were
designated nonattainment and for areas that were designated
unclassifiable/attainment alike.
(a) Options for Ongoing Verification
The use of modeling to characterize SO2 NAAQS-related
air quality and serve as a surrogate for monitoring raises the issue of
how a state will
[[Page 27466]]
continue to have data to assure ongoing attainment of the NAAQS. A
monitoring network provides data on a continuous basis, but any
modeling conducted pursuant to this rule to assess attainment of the
SO2 NAAQS for designations purposes would represent a
discrete 3-year period (similar to determining a 3-year design value
based on ambient monitoring data). A one-time modeling analysis using
actual emissions information would not provide for ongoing verification
of continued attainment.
For this reason, the EPA is proposing 3 policy options for how
states that satisfy the requirements of this rulemaking by using the
modeling option in a given area will need to conduct additional
emissions and/or modeling analyses to demonstrate continued attainment
for an area around a source. The EPA expects that such additional
analyses will be needed for areas that are designated as
``unclassifiable/attainment'' based on modeling information and would
be intended for the purpose of verifying that such areas continue to
meet the standard, just as monitors do now in many areas. The EPA also
presents 2 procedural options describing the process by which states
would provide an opportunity for public review and comment and submit
their report to the EPA and for the EPA to take action on the reports.
Before introducing the options for ongoing verification of
attainment, we note that source areas would not be subject to these
ongoing verification requirements if: (1) Modeling for the source was
conducted using allowable emissions; or (2) the modeling for the source
was conducted using actual emissions and the relevant sources then
adopted enforceable emission limits consistent with the actual
emissions rates used in the modeling. First, if an allowable emissions
rate were used in the modeling, then an enforceable emission limit
would already be in place to limit the source's emissions in the
future, so emissions would not be expected to exceed what was modeled.
Therefore, compliance with the emissions limit for areas associated
with these sources should be sufficient to ensure air quality meets the
standard and the EPA is not proposing additional means of verification
for such areas. Indeed, since use of actual emissions requires
recurring review to judge whether air quality may have worsened and
compliance with allowable emissions can demonstrate that no such review
would be necessary, states would have the incentive to use allowable
emissions limits in their modeling if it would demonstrate that
emissions at allowable levels would not cause violations of the NAAQS.
Second, for an area that was modeled as attaining the standard
based on actual source emissions, the state always has the option to
adopt for the source(s) in the area federally-enforceable emission
limits at levels that are consistent with the actual emissions used in
the modeling and that ensure attainment with the standard. These
emission limits would ensure that the source's emissions would not
increase in the future. Assuming the limits are adopted, enforceable
and being met by the time designations are completed, this approach
would require no additional submittal by the air agency after initial
designations beyond the usual ongoing source compliance demonstrations.
Under this approach, it would be assumed, subject to compliance
monitoring, that the source would remain in compliance with its
emission limits and the area would continue to attain the standard. If
a state does not take either of the approaches described above,
however, some mechanism for confirming that air quality continues to
meet the standard must be in place. Descriptions of the 3 proposed
options on which we request comment are presented below.
(1) Ongoing Verification Option 1
The first option would require the air agency to assess
SO2 emissions annually for sources that are located in areas
designated unclassifiable/attainment based on modeling using actual
emissions, and to conduct updated air quality modeling every 3 years.
On an annual basis, beginning the year after designations are
effective, the air agency will be required to provide an assessment of
the most recent emissions data for each source and whether it has
increased in emissions or changed its emissions profile (e.g., change
in operating schedule). Emissions data for large SO2 sources
would be made available by the state from annual reporting required for
the acid rain program, the air emissions reporting rule, or other
regulations. For each source, the air agency also will be required to
make a determination as to whether it finds that additional modeling is
needed to assess if the area around the source(s) is still attaining
the SO2 NAAQS. Factors the air agency should consider in
making this determination include: The estimated design value from the
original modeling analysis and how close that value was from exceeding
the standard; the magnitude of the emissions increase; and information
about changes in the emissions profile (e.g., operating schedule of the
source) or hourly emission rate. The EPA Regional Administrator will
assess the information provided by the air agency and determine on a
case-by-case basis if additional modeling will be requested from the
state to assess potential changes in air quality. If the air agency
determines that additional modeling is necessary, the EPA expects the
air agency to conduct such modeling and provide the results of that
assessment in a timely fashion.
In the third year after designations are effective and continuing
every 3 years after that, the air agency would also be required to
submit a modeling analysis assessing the air quality around each
source(s) using actual annual emissions and meteorological data from
the most recent 3 years. Based on this analysis, the air agency will
need to determine whether the area is still attaining the
SO2 NAAQS. If any new modeling by the air agency indicates
that an area is not attaining the SO2 NAAQS, the EPA may
take appropriate action, including, but not limited to, requiring
adoption of enforceable emission limits to ensure continued attainment
of the SO2 NAAQS, redesignation to nonattainment, or
issuance of a SIP Call. Air agencies may request that the EPA Regional
Administrator approve a suspension of the triennial modeling
requirement for an area if their most recent modeling design value is
less than 50 percent of the NAAQS and if that modeling is not also
required as part of a SIP or permit. Note that for such areas, the air
agency will still be required to provide an annual assessment of the
most recent emissions data for each source and whether it has increased
in emissions or changed its emissions profile (e.g., change in
operating schedule).
The EPA believes that this approach is appropriate for assessing
ongoing attainment of the SO2 NAAQS, as it follows a similar
approach to what states would be required to do if there was a monitor
near a source. The EPA believes that this approach would be a
reasonable way to provide for an ongoing assessment of key sources.
Recognizing state resource limitations, this approach does not require
air agencies to conduct modeling for each source every year, and, in
the years when modeling is required, much of the information from prior
modeling will likely continue to be applicable (e.g., stack parameters,
terrain). Thus, compared to a situation in which the air agency would
be required to operate and maintain an ambient monitor to ensure
ongoing attainment, this
[[Page 27467]]
requirement to track emissions annually and conduct updated modeling
every 3 years provides appropriate ongoing characterization of air
quality while being less burdensome than monitoring for the air agency.
The EPA is also proposing two alternative options for comment below.
(2) Ongoing Verification Option 2
The second option would also require the air agency to provide the
EPA with an assessment of SO2 emissions changes for each
source annually, beginning in the year after the area is designated
unclassifiable/attainment. This annual review of emissions would be
similar to the requirement discussed in the first option. As noted
above, emissions data for large SO2 sources would be
available from annual reporting required for the acid rain program, the
air emissions reporting rule, or other regulations. However, instead of
modeling every 3 years, EPA would require that, for each source in
which total SO2 emissions increase over the emissions for
the previous year, the air agency would be required to submit to the
EPA an assessment of the cause of the increase and provide an initial
determination of whether or not air quality modeling would be needed to
verify that the area around the source continues to attain the
standard. Factors the air agency should consider in making this
determination include: The estimated design value from the original
modeling analysis and how close that value was from exceeding the
standard; the magnitude of the emissions increase; and information
about changes in the emissions profile or hourly emission rate.
For example, if the previous modeling of actual emissions in the
area estimated the design value to be just below the level of the
standard and 5 years later the area emissions increased by 15 percent,
then this likely would be a sufficient reason for the air agency to
conduct an updated modeling analysis.\46\ On the other hand, if the
initial modeling using actual emissions for the area indicated that the
design value would be less than half the level of the standard and in a
subsequent year indicated the area emissions increased by 5 percent,
then this might be a sufficient reason for the air agency to recommend
that it does not need to conduct an updated modeling analysis.
---------------------------------------------------------------------------
\46\ Moreover, the prevention of significant deterioration
program would likely require such an analysis if the emissions
increase originated from a major modification to an existing source.
---------------------------------------------------------------------------
The Regional Administrator would consider the air agency
recommendation for each area around a source on a case-by-case basis
and may direct the air agency to conduct an updated modeling analysis
using the SO2 emissions from the most recent 3 years and to
submit the results of such analysis to the EPA Regional Office by a
specific date. If the air agency determines that additional modeling is
necessary, the EPA expects the air agency to conduct such modeling and
provide the results of that assessment in a timely fashion--within 12
months. The EPA will consider the results of any updated modeling
analysis in order to determine whether the area continues to attain.
The EPA believes that this option strikes a balance between
analytical burden and air quality protection because it provides a
simple, easy-to-track benchmark for requiring further investigation of
an emissions increase by the air agency, and it allows the Regional
Administrator to first consider the air agency's analysis of each
particular case before determining whether a more resource-intensive
modeling analysis would be required. The EPA believes that this option
would be a reasonable alternative to option 1 for requiring some
further assessment of source areas, but a key difference is that it
would not require modeling every 3 years. Because modeling likely would
be required less frequently under this option, it would be less
resource intensive than option 1, but the verification of ongoing
attainment would not reflect the same degree of certainty as option 1.
(3) Ongoing Verification Option 3
Under the third option, the state would be required to perform
periodic screening modeling every 3 years for all source areas that had
been previously modeled and determined to be attaining the standard,
and submit such modeling for review to the EPA. Screening modeling
typically uses conservative assumptions to determine whether an area
around a source(s) would still be expected to attain the standard, and
it requires less work by the air agency in preparing model inputs as
compared to preparing for a full-scale modeling analysis. The companion
screening model for AERMOD is the AERSCREEN model. A complete, full-
scale modeling analysis with updated emissions and meteorological
inputs would only be required if the state performs screening modeling
that indicates a potential violation.
If this new full-scale modeling by the air agency indicates that an
area is not attaining the SO2 NAAQS, the EPA may take
appropriate action, including, but not limited to, requiring adoption
of enforceable emission limits to ensure continued attainment of the
SO2 NAAQS, redesignation to nonattainment, or issuance of a
SIP Call. The basic rationale behind this option is that since these
areas were designated as unclassifiable/attainment based on modeling,
then it would be appropriate to require periodic updated modeling to
continue to verify attainment. Because the states will have already
gone through the process of modeling these sources, it is expected that
it will be less resource intensive to conduct this periodic screening
modeling in subsequent years.
(b) Procedural Options for Ongoing Verification
As with the prior section regarding ongoing verification following
removal of a monitor, the EPA also proposes two options regarding the
procedure by which air agencies would submit ongoing verification
reports to the EPA when a state elects to use the modeling option and
the procedure by which the EPA would review and act on them. The
contents of the verification report will depend on which of the above
policy options is ultimately finalized.
(1) Procedural Option 1
Under the first procedural option, we propose that in order to
demonstrate ongoing verification of attainment for sources that have
been designated unclassifiable/attainment based on modeling analyses,
the air agency would submit a report to the EPA annually as an appendix
to its annual monitoring plan. The annual monitoring plan is required
to be submitted to the EPA Regional Administrator by July 1 each year.
This annual process for verifying ongoing attainment for areas
designated attainment based on modeling in effect would be a surrogate
for ongoing ambient monitoring (which would provide a new 3-year design
value with each new year of air quality data). A primary objective of
this approach would be to enable the air agency to save time and
resources by providing a single process for the public review and
comment on the annual monitoring plan and annual reports to demonstrate
ongoing attainment of previously modeled areas.
The inclusion of this verification report as an appendix to the
annual monitoring plan would ensure that the report would be subject to
the same opportunities for public review and comment that are to be
provided for the monitoring plan pursuant to regulations at 40 CFR Part
58.10. Those regulations specify that if the air agency modifies the
monitoring plan from the previous
[[Page 27468]]
year, then prior to taking final action to approve or disapprove the
plan, the EPA would be required to provide an opportunity for public
comment on its proposed action. The regulations also indicate that if
the state has already provided a public comment opportunity in
developing its revised monitoring plan and has made no further changes
to the plan after reviewing public comments that were received, then it
could submit the public comments along with the revised plan to the
EPA, and the Regional Administrator would not need to provide a
separate opportunity for comment before approving or disapproving the
plan.
(2) Procedural Option 2
Under the second procedural option, the ongoing verification of
emissions report would not be submitted to the EPA as an appendix to
the annual monitoring network plan. Instead, it would take the form of
a separate, independent submittal from the state to the EPA Regional
Administrator. However, we propose that this report would be due by the
same July 1 date each year. This independent submittal would follow the
general guidelines set forth in 40 CFR 58.10 regarding opportunities
for public review as described in option 1 above, but the report would
only include the annual assessments associated with sources in areas
that were designated unclassifiable/attainment based on modeling of
actual emissions.
The EPA believes that the main advantage of the first procedural
option is that from a procedural standpoint, it would leverage the time
and resources that are already devoted to the existing annual
monitoring plan development and review process. In contrast, the second
option would require additional state and the EPA resources to provide
for public review opportunities in parallel with the monitoring plan
process. The main advantage of the second option is that it would keep
the information submitted to verify ongoing attainment for modeled
areas separate from the annual monitoring plan. It may be considered
advantageous from the perspective of managing workflow in an air
quality management organization to not have the modeling verification
reports be combined with the annual modeling plans.
Regardless of which procedural approach is included in the final
rule, the EPA would communicate to each state the reasoning behind any
action or decision the EPA makes with regard to the submitted ongoing
verification of attainment report. For example, the EPA should describe
the supporting rationale for a decision to require additional
monitoring from the state, or for a decision to allow the state to
suspend the periodic modeling requirement for a source because the
latest modeled design value is below 50 percent of the NAAQS. This
information should be provided in writing in a letter or Federal
Register document, as appropriate. The EPA seeks to adopt an effective
approach for verifying ongoing attainment for modeled source areas that
can serve as a reasonable surrogate to ongoing ambient monitoring
without creating undue burden for states.
The EPA requests comment on the 3 policy options presented above,
and requests that each commenter provide a clear rationale for their
position. The EPA also requests comments on the two procedural options
presented above. For both sets of options, the EPA would be interested
in any alternative ideas suggested by commenters. For any such
recommendations, the EPA requests the commenter provide a detailed
rationale and estimate of any associated costs.
VI. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review
Under Executive Order 12866 (58 FR 51735, October 4, 1993), this
action is a ``significant regulatory action'' because it raises novel
policy issues. Accordingly, the EPA submitted this action to OMB for
review under Executive Orders 12866 and 13563 (76 FR 3821, January 21,
2011) and any changes made in response to OMB recommendations have been
documented in the docket for this action.
B. Paperwork Reduction Act
The information collection requirements in this proposed rule have
been submitted for approval to the OMB under the Paperwork Reduction
Act, 44 U.S.C. 3501 et seq. The Information Collection Request (ICR)
document prepared by the EPA has been assigned the EPA ICR number
2495.01.
The EPA is proposing this SO2 Data Requirements rule to
require air agencies to more extensively characterize ambient
SO2 air quality concentrations, pursuant to section
110(a)(2)(B) and 110(a)(2)(K) of the CAA, to inform the area
designations process for the 2010 SO2 NAAQS. For purposes of
analysis of the estimated paperwork burden, the EPA assumed that 47
states and tribes would take actions to characterize air quality
through either air quality modeling or ambient monitoring in 443 areas
across the country and such states would submit the results of these
analyses to the EPA. Under this rule, the air agency will have the
ability to choose, on an area-by-area basis, the analytical approach to
follow for characterizing air quality around each qualifying source.
For this reason, there is no way of determining exactly how many areas
may be characterized through ambient monitoring versus air quality
modeling approaches. Therefore, this section presents two sets of
estimated costs, one that assumes all sources would be characterized
through ambient monitoring, and the other that assumes that all sources
would be characterized through air quality modeling.
Potential ambient air monitoring costs are estimated based on the
assumption that air quality for each of the 443 SO2 sources
exceeding the Option 1 threshold would be characterized through a
single newly deployed air monitor. (Note, however, that the Monitoring
TAD discusses situations where more than one monitor may be appropriate
or necessary to properly characterize peak 1-hour SO2
concentrations in certain areas.) Estimates are provided for a 3 year
period and include a calculation for equipment amortization over seven
years (as is typically done in monitoring-related ICRs). For the period
of 2016, 2017, and 2018 (the SO2 requirement begins in
2016), the total approximate average annual monitoring cost, including
a calculation for equipment amortization is $9,308,824 (total capital,
and labor and non-labor operation and maintenance) with a total burden
of 110,543 hours. The annual labor costs associated with these hours is
$7,608,287. Included in the $9,308,824 total are other annual costs of
non-labor operations and maintenance of $760,011 and equipment and
contract costs of $940,526. For reference purposes, an estimate for
initial establishment of a new SO2 monitoring station is
$92,614 (does not include equipment amortization). In addition to the
costs that would be incurred by the state and local air agencies, there
would be an estimated burden to the EPA of a total of 52,717 hours and
$776,005. Burden is defined at 5 CFR 1320.3(b).
Potential air quality modeling costs are estimated based on the
assumption that air quality for each of the 443 SO2 sources
exceeding the Option 1 threshold would be characterized through air
quality modeling analyses. Based on market research, stakeholder
feedback, and assumptions about the
[[Page 27469]]
procedures to follow when conducting modeling for designations
purposes,\47\ an estimate of modeling costs for a single modeling run
centered on an identified source would be approximately $30,000. If
states choose to characterize air quality through modeling analyses
around all 443 sources identified under source threshold Option 1, then
total national costs for modeling analyses would be estimated at
$13,300,000. If these costs were incurred over the course of three
years, then the approximate annual cost for each year over that period
would be $4,433,333.
---------------------------------------------------------------------------
\47\ The Draft SO2 NAAQS Designations Modeling
Technical Assistance Document can be found at http://www.epa.gov/airquality/sulfurdioxide/pdfs/SO2ModelingTAD.pdf.
---------------------------------------------------------------------------
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 the
EPA's regulations in 40 CFR are listed in 40 CFR part 9.
To comment on the agency's need for this information, the accuracy
of the provided burden estimates and any suggested methods for
minimizing respondent burden, the EPA has established a public docket
for this rulemaking, which includes this ICR, under Docket ID number
EPA-HQ-OAR-2013-0711. Commenters should submit any comments related to
the ICR to both the EPA and OMB. See the ADDRESSES section at the
beginning of this notice for where to submit comments to the EPA. Send
comments to OMB at the Office of Information and Regulatory Affairs,
Office of Management and Budget, 725 17th Street NW., Washington, DC
20503, Attention: Desk Office for the EPA. Since OMB is required to
make a decision concerning the ICR between 30 and 60 days after May 13,
2014, a comment to OMB is best assured of having its full effect if OMB
receives it by June 12, 2014. The final rule will respond to any OMB or
public comments on the information collection requirements contained in
this proposal.
C. Regulatory Flexibility Act
The Regulatory Flexibility Act (RFA) generally requires an agency
to prepare a regulatory flexibility analysis of any regulation subject
to notice and comment rulemaking requirements under the Administrative
Procedures Act or any other statute unless the agency certifies 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 proposed rule on
small entities, small entity is defined as: (1) A small business as
defined in 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; and (3) a small organization
that is any not-for-profit enterprise which is independently owned and
operated and is not dominant in its field.
After considering the economic impacts of this proposed rule 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 directly on small
entities. Entities potentially affected directly by this proposal
include state, local and tribal governments and none of these
governments are small governments. Other types of small entities are
not directly subject to the requirements of this rulemaking. 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
This action contains no federal mandate under the provisions of
title II of the Unfunded Mandates Reform Act of 1995 (UMRA), 2 U.S.C.
1531-1538 for state, local and tribal governments, in the aggregate, or
the private sector. This action imposes no enforceable duty on any
state, local or tribal governments or the private sector. Therefore,
this action is not subject to the requirements of section 202 and 205
of the UMRA.
This action is also not subject to the requirements of section 203
of the UMRA because it contains no regulatory requirements that might
significantly or uniquely affect small governments. The CAA imposes the
obligation for states to submit information to the EPA to characterize
air quality in order for such data to inform the area designations
process following the revision of a NAAQS. This rule interprets the
requirements in section 110(a)(2)(B) and 110(a)(2)(K) in order for air
agencies to more broadly characterize ambient SO2
concentrations for the SO2 NAAQS designations process.
E. Executive Order 13132: Federalism
This action 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 13132. The requirement to characterize air
quality to inform the area designation process for a revised NAAQS is
imposed by the CAA. This proposed rule, if made final, would interpret
those requirements as they apply to the 2010 SO2 NAAQS.
Thus, Executive Order 13132 does not apply to these proposed
regulations.
In the spirit of Executive Order 13132 and consistent with the EPA
policy to promote communications between the EPA and state and local
governments, the EPA specifically solicits comments on this proposed
action from state and local officials. In addition, the EPA intends to
meet with organizations representing state and local officials during
the comment period for this action.
F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments
This proposed action does not have tribal implications, as
specified in Executive Order 13175 (65 FR 67249, November 9, 2000). It
would not have a substantial direct effect on one or more Indian
tribes. Furthermore, these proposed regulation revisions do not affect
the relationship or distribution of power and responsibilities between
the federal government and Indian tribes. The CAA and the Tribal Air
Rule establish the relationship of the federal government and tribes in
characterizing air quality and developing plans to attain the NAAQS,
and these revisions to the regulations do nothing to modify that
relationship. Thus, Executive Order 13175 does not apply to this
action.
Although Executive Order 13175 does not apply to this action, the
EPA held several meetings with tribal environmental professionals to
discuss issues associated with this rule, including discussions at the
National Tribal Forum on May 1, 2013, and on National Tribal Air
Association policy calls. These meetings discussed the SO2
implementation White Paper. The EPA also provided an opportunity for
tribes and stakeholders to provide written comments on the concepts
discussed in the White Paper. Summaries of these meetings are included
in the docket for this proposed rule. The EPA specifically solicits
additional comment on this proposed action from tribal officials. The
EPA also intends to offer to consult with any tribal government to
discuss this proposal.
[[Page 27470]]
G. Executive Order 13045: Protection of Children From Environmental
Health and Safety Risks
The EPA interprets E.O. 13045 (62 FR 19885, April 23, 1997) as
applying only to those regulatory actions that concern health or safety
risks, such that the analysis required under section 5-501 of the E.O.
has the potential to influence the regulation. This action is not
subject to E.O. 13045 because it does not establish an environmental
standard intended to mitigate health or safety risks. These proposed
regulatory provisions are designed to help implement the already-
established SO2 NAAQS, which was promulgated in 2010 to
protect the health and welfare of individuals, including children, who
are susceptible to the adverse effects of exposure to unhealthy levels
of ambient SO2.
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 (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 the 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 (e.g., materials specifications, test methods,
sampling procedures and business practices) that are developed or
adopted by voluntary consensus standards bodies. NTTAA directs the EPA
to provide Congress, through OMB, explanations when the agency decides
not to use available and applicable voluntary consensus standards.
This proposed rulemaking does not involve technical standards.
Therefore, the EPA is not considering 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 (E.O.) 12898 (59 FR 7629 (Feb. 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. The proposed regulations would, if promulgated, require
air agencies to characterize ambient SO2 air quality levels
more extensively throughout the country, particularly in areas near
large emissions sources. The EPA has designed options in this proposed
rule that would require air agencies to characterize air quality around
smaller emissions sources, if such sources are located in more highly
urbanized areas, because such areas would have the potential for a
greater number of people to be exposed to adverse effects of ambient
SO2 concentrations. This aspect of the proposed rule can
help to ultimately provide additional protection for minority, low
income and other populations located in these urbanized areas. As such,
the EPA finds that this proposed rule would not adversely affect the
health or safety of minority or low-income populations, and that it is
designed to protect and enhance the health and safety of these and
other populations.
Statutory Authority
The statutory authority for this action is provided by 42 U.S.C.
7403, 7407, 7410 and 7601.
List of Subjects in 40 CFR Part 51
Environmental protection, Air pollution control, Intergovernmental
relations, Sulfur oxides.
Dated: April 17, 2014.
Gina McCarthy,
Administrator.
For the reasons stated in the preamble, title 40, chapter I, part
51 of the Code of Federal Regulations are proposed to be amended as
follows:
PART 51--REQUIREMENTS FOR PREPARATION, ADOPTION AND SUBMITTAL OF
IMPLEMENTATION PLANS
0
1. The authority citation for Part 51 continues to read as follows:
Authority: 23 U.S.C. 101; 42 U.S.C. 7401-7671q.
0
2. Add Subpart BB to read as follows:
Subpart BB--Data Requirements for Characterizing Air Quality for the
Primary SO2 NAAQS
Sec.
51.1200 Definitions.
51.1201 Purpose.
51.1202 Applicability.
51.1203 Air agency requirements.
51.1204 Enforceable emission limits.
51.1205 Assuring continued attainment.
Subpart BB--Data Requirements for Characterizing Air Quality for
the Primary SO2 NAAQS
Sec. 51.1200 Definitions.
The following definitions apply for the purposes of this subpart.
All terms not defined herein will have the meaning given them in
section 51.100 of this part or in the CAA. 2010 SO2 NAAQS means the
primary NAAQS for SO2 as codified at 40 CFR 50.17, as
promulgated on June 2, 2010.
Air agency means the agency or organization responsible for air
quality management within a state, local governmental jurisdiction,
territory or area subject to tribal government.
Annual SO2 emissions data means the quality-assured annual
SO2 emissions data for a stationary source as reported to
the EPA in accordance with any existing regulatory requirement (such as
the National Emissions Inventory, the Acid Rain Program database, or
the Clean Air Interstate Rule database).
Applicable source means a stationary source that has annual
SO2 emissions of 2000 tons or more; has annual
SO2 emissions of 1000 tons or more and is located within a
CBSA with a population equal to or greater than 1 million persons; or
has been identified by the air agency or by the EPA Regional
Administrator as requiring further air quality characterization.
CBSA means core based statistical area, as defined and maintained
by the Office of Management and Budget (OMB) pursuant to OMB Bulletin
13-01 (February 28, 2013). The most recent revision to CBSA definitions
were developed in accordance with OMB's ``Standards for Delineating
Metropolitan and Micropolitan Statistical Areas,'' 75 FR 37246 (June
28, 2010).
Sec. 51.1201 Purpose.
The purpose of this subpart is to require air agencies to take
actions to develop air quality data characterizing maximum 1-hour
ambient concentrations of SO2 more extensively across the
United States through either additional ambient air quality
[[Page 27471]]
monitoring or air quality modeling analyses at the air agency's
election. Such additional monitoring and modeling data may be used in
future initial area designations by the EPA, or for other actions
designed to ensure attainment of the 2010 SO2 NAAQS and
provide protection of the public from the short-term health effects
associated with exposure to SO2 concentrations that exceed
the NAAQS.
Sec. 51.1202 Applicability.
This subpart applies to any air agency in whose jurisdiction is
located one or more applicable sources of SO2 emissions that
has annual SO2 emissions of 2,000 tons or more; has annual
SO2 emissions of 1,000 tons or more and is located within a
CBSA with a population equal to or greater than 1 million persons; or
has been identified by the air agency or by the EPA Regional
Administrator as requiring further air quality characterization. The
subject air agency shall identify applicable sources of SO2
based on the most recent publicly available annual SO2
emissions data for such sources.
Sec. 51.1203 Air agency requirements.
(a) The air agency shall submit a list of applicable sources
located in its jurisdiction to the EPA by January 15, 2016. This list
may be revised by the Regional Administrator after review based on
available SO2 emissions data.
(b) For each area containing an applicable source, the air agency
shall state by January 15, 2016, whether it will characterize air
quality through ambient air quality monitoring or through air quality
modeling techniques. For any area with multiple applicable sources, the
air agency (or air agencies if a multi-state area) shall use the same
technique (monitoring or modeling) to characterize air quality for all
sources in the area.
(c) Monitoring. For any area for which air quality will be
characterized through ambient monitoring, the monitors shall be sited
and operated in a manner equivalent to SLAMS, including, but not
limited to being subject to reporting data to AQS, data certification
and satisfying criteria in 40 CFR part 58 Appendices A, C and E. The
air agency shall include relevant information about monitors used to
characterize air quality in areas with applicable sources in the air
agency's annual monitoring network plan required by 40 CFR 58.10. The
air agency shall consult with the appropriate the EPA Regional Office
in the development of plans to install, supplement, or maintain an
appropriate ambient SO2 monitoring network pursuant to the
requirements of 40 CFR part 58 and this proposed rule. The air agency's
annual monitoring network plan due on July 1, 2016 shall reflect such
monitoring and ensure that such monitors will be operational by January
1, 2017.
(1) All existing, new or relocated ambient monitors intended to
satisfy section 51.1203(b) must be operational by January 1, 2017.
(2) By no later than May 1, 2020, the air agency shall determine
whether any new ambient monitoring sites deployed pursuant to this
subpart indicate a violation of the 2010 SO2 NAAQS based on
ambient monitoring data from the most recent 3 calendar years.
(3) Any SO2 monitor identified by an air agency in its
approved Annual Monitoring Network Plan as having the purpose of
satisfying section 51.1203(b) of this proposed rule and which is not in
an SO2 nonattainment area, and is not also being used to
satisfy other ambient SO2 minimum monitoring requirements
listed in 40 CFR part 58 Appendix D, section 4.4, or which may
otherwise be required as part of a SIP or permit, and that produces a
design value of no greater than fifty percent of the 1-hour
SO2 NAAQS, may be eligible for shut-down. The air agency
must receive the EPA Regional Administrator approval prior to the shut-
down of any qualifying monitor.
(d) Modeling. For each area for which air quality will be
characterized through air quality modeling, the air agency shall submit
by January 15, 2016, a technical protocol for conducting such modeling
to the Regional Administrator for review. The air agency shall consult
with the appropriate the EPA Regional Office in developing these
modeling protocols.
(1) The modeling protocol shall include information about the
modeling approach to be followed, including but not limited to the
model to be used, modeling domain, receptor grid, emissions dataset,
meteorological dataset and how the state will account for background
SO2 concentrations.
(2) Modeling analyses shall characterize air quality based on
either actual 1-hour SO2 emissions from the most recent 3
years, or federally enforceable allowable emissions. If the air agency
intends to use allowable emissions limits for this analysis, it may
submit such allowable emissions limits for the EPA's approval at the
time the modeling protocol is submitted.
(3) The air agency shall conduct the modeling analysis for any
applicable source identified by the air agency pursuant to section
51.1203(a), and for its associated area and any nearby area, as
applicable, and submit the modeling analysis to the EPA Regional Office
by January 13, 2017.
Sec. 51.1204 Enforceable emission limits.
At any time prior to January 13, 2017, for any area that does not
have an initial area designation conducted pursuant to section 107(d)
of the CAA, the air agency may submit to the EPA for an applicable
source a currently applicable and federally enforceable SO2
emissions limit or limits, associated air quality modeling, and other
analyses that demonstrate the area, and any nearby area, as applicable,
does not violate the 2010 SO2 NAAQS, and that the source
emissions limit will ensure continued attainment. The EPA will consider
such enforceable emissions limits and modeling demonstrations in the
initial designations process for these areas.
Sec. 51.1205 Assuring continued attainment.
(a) For any area in which one or more applicable sources is located
and which has been initially designated attainment pursuant to this
proposed rule based on ambient monitoring data or based on a modeling
analysis using recent actual emissions, the air agency shall ensure
that the area continues to attain the 2010 SO2 NAAQS in
subsequent years.
(b) Modeled areas. For any area initially designated attainment
where modeling of actual emissions was conducted to characterize air
quality to satisfy the requirements listed in 51.1203 of this part, the
air agency shall submit a report to the EPA Regional Administrator as
an appendix to its annual monitoring plan (due on July 1 each year per
40 CFR 58.10) documenting the annual SO2 emissions of each
applicable source in each such area and providing an assessment of the
cause of any emissions increase. The first report for each such area is
due by July 1 of the year after the effective date of the area's
initial designation.
(1) Along with the annual emissions report, the air agency shall
provide a recommendation regarding whether additional modeling is
needed to characterize air quality in any area to determine whether it
continues to attain the 2010 SO2 NAAQS. The EPA Regional
Administrator will consider the emissions report and air agency
recommendation, and may require that the air agency conduct updated air
quality modeling for the area and submit it to the EPA by a specified
date.
(2) For any area initially designated attainment where modeling of
actual emissions was conducted to characterize air quality, the air
agency also shall submit to the EPA an updated air quality modeling
analysis by July 1 of the third year after the designation for
[[Page 27472]]
the area is effective every 3 years thereafter.
(3)(i) The air agency may request that the EPA Regional
Administrator approve ceasing continued triennial modeling of the area
as required by paragraph (b)(2) of this section if the following
criteria are met:
(A) the modeling is not otherwise required to meet any requirement
in a SIP or permit; and
(B) the most recent modeling for the area resulted in a modeled
design value that is no greater than fifty percent of the 1-hour
SO2 NAAQS.
(4) The EPA will act upon such a request to cease triennial
modeling as part of its action on the annual monitoring plan under 40
CFR 58.10. For areas where the EPA has approved the air agency's
request to cease continued modeling of the area, the air agency will be
required to continue to meet the requirements of paragraphs (b) and
(b)(1) of this section.
(c) Monitored areas. For any area initially designated attainment
where SO2 monitoring was conducted to characterize air
quality to satisfy the requirements listed in section 51.1203 of this
part, the air agency shall continue to operate the monitor(s) used to
satisfy those requirements and report ambient data pursuant to existing
ambient monitoring regulations.
(1)(i) The air agency may request that the EPA Regional
Administrator approve the shut-down of any monitor in operation to
satisfy the requirements of section 51.1203 of this part if the
following criteria are met:
(A) the monitor is not also satisfying other minimum SO2
monitoring requirements listed in 40 CFR part 58 Appendix D;
(B) the monitor is not otherwise required to meet any requirement
in a SIP or permit; and
(C) the monitor recorded a design value in the most recent 3-year
period that is no greater than fifty percent of the 1-hour
SO2 NAAQS.
(ii) The EPA will act upon any request to cease operation of a
monitor as part of its action on the annual monitoring plan under 40
CFR 58.10.
(2) For any area for which the EPA has approved the air agency's
request for an SO2 monitor to cease operations, the air
agency shall submit a report to the EPA Regional Administrator as an
appendix to its annual monitoring plan (due on July 1 each year per 40
CFR 58.10) documenting the annual SO2 emissions of each
applicable source in each such area and providing an assessment of the
cause of any emissions increase. The first report for each such area is
due by July 1 of the year after the monitor operations were terminated.
(3) Along with the annual emissions report, the air agency shall
provide a recommendation regarding whether additional air quality
characterization is needed to determine whether the area continues to
attain the 2010 SO2 NAAQS. The EPA Regional Administrator
will consider the emissions report and air agency recommendation, and
may require that the air agency reinstate ambient monitoring or conduct
additional modeling and submit relevant data to the EPA by a specified
date.
(d) If modeling or monitoring information required to be submitted
by the air agency to the EPA pursuant to section 51.1205 of this part
indicates that an area is not attaining the 2010 SO2 NAAQS,
the EPA may take appropriate action, including but not limited to,
disapproving the monitoring plan, requiring adoption of enforceable
emission limits to ensure continued attainment of the 2010
SO2 NAAQS, redesignation of the area to nonattainment, or
issuance of a SIP Call.
[FR Doc. 2014-09458 Filed 5-12-14; 8:45 a.m.]
BILLING CODE 6560-50-P