[Federal Register Volume 80, Number 162 (Friday, August 21, 2015)]
[Rules and Regulations]
[Pages 51052-51088]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-20367]
[[Page 51051]]
Vol. 80
Friday,
No. 162
August 21, 2015
Part V
Environmental Protection Agency
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40 CFR Part 51
Data Requirements Rule for the 2010 1-Hour Sulfur Dioxide
(SO2) Primary National Ambient Air Quality Standard (NAAQS);
Final Rule
Federal Register / Vol. 80 , No. 162 / Friday, August 21, 2015 /
Rules and Regulations
[[Page 51052]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 51
[EPA-HQ-OAR-2013-0711; FRL-9928-18-OAR]
RIN 2060-AR19
Data Requirements Rule for the 2010 1-Hour Sulfur Dioxide
(SO2) Primary National Ambient Air Quality Standard (NAAQS)
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: The Environmental Protection Agency (EPA) is promulgating 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 to identify maximum 1-hour
SO2 concentrations in ambient air. The final rule
establishes minimum criteria for identifying the emissions sources and
associated areas for which air agencies are required to characterize
SO2 air quality. Air agencies remain free to also
characterize air quality in additional areas beyond those required to
be characterized under the rule. The final rule also sets forth a
process and timetables by which air agencies must characterize air
quality 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 recommending how air
agencies should conduct such monitoring or modeling. The air quality
data developed by air agencies pursuant to this rule may be used by the
EPA in future actions to evaluate areas' air quality under the 2010 1-
hour SO2 National Ambient Air Quality Standard (NAAQS),
including area designations and redesignations, as appropriate.
DATES: This final rule is effective on September 21, 2015.
ADDRESSES: The EPA has established a docket for this action under
Docket ID No. EPA-HQ-OAR-2013-0711. All documents in the docket are
listed on the http://www.regulations.gov Web site. Although listed in
the index, some information is not publicly available, i.e.,
confidential business information or other information whose disclosure
is restricted by statute. Certain other material, such as copyrighted
material, will be publicly available only in hard copy. Publicly
available docket materials are available either electronically in
http://www.regulations.gov or in hard copy at the Docket ID No. EPA-HQ-
OAR-2013-0711, EPA/DC, William Jefferson Clinton West Building, Room
3334, 1301 Constitution Avenue 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 and the telephone number for the Air and
Radiation Docket Information Center is (202) 566-1742. For additional
information about the EPA's public docket, visit the EPA Docket Center
homepage at: http://www.epa.gov/epahome/dockets.htm.
FOR FURTHER INFORMATION CONTACT: For further general information on
this rulemaking, contact Dr. Larry D. Wallace, Office of Air Quality
Planning and Standards, U.S. Environmental Protection Agency, by phone
at (919) 541-0906, or by email at [email protected]; or Mr. Rich
Damberg, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, by phone at (919) 541-5592, or by
email at [email protected].
SUPPLEMENTARY INFORMATION:
I. General Information
A. Does this action apply to me?
Entities potentially affected directly by this final rulemaking
include state, local and tribal governments. Entities potentially
affected indirectly by this final rulemaking, depending on how state,
local and tribal agencies choose to regulate such entities in the
future, include owners and operators of sources of SO2
emissions (such as coal-fired power plants, refineries, smelters, pulp
and paper related facilities, waste incinerators, chemical
manufacturers 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. 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 document will be posted at: http://www.epa.gov/air/sulfurdioxide/implement.html. Upon its publication in the Federal Register, only the
published version may be considered the final official version of the
notice, and will govern in the case of any discrepancies between the
Federal Register published version and any other version.
C. 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. Where can I get a copy of this document and other related
information?
C. How is this document organized?
II. Background for Final Rulemaking
III. Summary of the Final Rule Requirements
IV. Responses to Significant Comments on the Proposed Rule
A. The Use of Monitoring and/or Modeling Data
B. Source Coverage and Emission Threshold Options
C. Data Requirements and Program Implementation Timeline
D. Technical Issues Relating to Modeling and Monitoring
E. Other Key Issues and Comments
V. Environmental Justice Considerations
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 (PRA)
C. Regulatory Flexibility Act (RFA)
D. Unfunded Mandates Reform Act (UMRA)
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
K. Congressional Review Act (CRA)
L. Judicial Review
Statutory Authority
II. Background for Final Rulemaking
On May 13, 2014, the EPA proposed the Data Requirements Rule (DRR)
for the 2010 1-hour SO2 Primary NAAQS. The preamble to the
proposal provided a discussion of the events that led to the EPA's
proposal of a new regulation to direct state, tribal and local agencies
\1\ to better characterize ambient air SO2 concentrations
near large polluting sources. See 79 FR 27447, May 13, 2014. This
discussion addressed the adoption of the 2010 SO2 NAAQS and
the suggested implementation approach described in the preamble of that
rulemaking; the area designations process under section 107 of the
Clean Air Act (CAA); the history of
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designations for prior SO2 NAAQS, including the use of air
quality modeling information; the Agency's subsequent issuance of an
implementation white paper in May 2012 and input received from
stakeholder groups; and the EPA's February 2013 SO2 NAAQS
implementation and designations strategy paper, developed in response
to feedback received through this outreach process.\2\ This final
rulemaking notice does not repeat all of that discussion, but refers
interested readers to the preamble of the proposed rule for this
informative background.
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\1\ The final rule applies to air agencies in all states. The
definition of ``state'' in section 302(d) of the Clean Air Act (CAA
or Act) means a state, the District of Columbia, the Commonwealth of
Puerto Rico, the Virgin Islands, Guam, and American Samoa and
includes the Commonwealth of the Northern Mariana Islands.
\2\ 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.
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The proposed rule noted that although the current SO2
ambient monitoring network included more than 400 monitors nationwide,
the scope of the network had certain limitations, and approximately
two-thirds of the monitors are not located to characterize maximum 1-
hour SO2 concentration impacts from emissions sources. To
more effectively assess potential public health impacts from exposure
to high SO2 concentrations, the proposed rule presented
options for requiring air agencies to characterize air quality in the
vicinity of large sources of SO2 emissions that exceed
specified annual emissions thresholds. The EPA's proposed preferred
emissions threshold option specified that air agencies would be
required to characterize air quality in the vicinity of sources that
emit over 1,000 tons of SO2 per year and are located in more
highly populated areas (i.e., Core-Based Statistical Areas (CBSA) with
population of at least 1 million), and in the vicinity of sources that
emit over 2,000 tons of SO2 per year and are located outside
metropolitan areas of at least 1 million population. The EPA also
identified two other emission threshold options and requested public
comment on these potential emission thresholds values, a CBSA
population threshold of 1 million, the combination of emissions and
population thresholds as a means of determining how SO2
sources would be identified, and on any possible alternatives. Under
the proposed approach, air agencies, or the EPA, also could require air
quality characterization around other sources, if warranted. See 79 FR
27453, May 13, 2014.
Under the proposed rule, air agencies would determine for each
emissions source exceeding the threshold whether air quality
characterization for that source would be done either through air
quality modeling analysis or by conducting ambient monitoring. Apart
from the proposed rule, the EPA issued two draft technical assistance
documents (TADs) on modeling and monitoring to assist air agencies with
this analytical work. The proposed rule also described a process and
timetable by which air agencies would be required to identify sources
to be characterized, conduct the relevant analyses and submit such data
to the EPA. See 79 FR 27456, May 13, 2014.
Specific technical considerations regarding air quality monitoring
and modeling were also discussed in the proposed rule, along with
options for ongoing verification of the air quality characterization in
areas that are not otherwise designated as nonattainment. See 79 FR
27460, May 13, 2014. The proposal also discussed incentives for air
agencies and sources to work together to establish federally
enforceable limits on emissions expeditiously in order to avoid
requirements for air quality characterization altogether. We refer
readers to the proposed rule for the technical, policy and legal
rationale that were presented in support of the proposal, and for a
complete discussion of the issues for which the EPA requested public
comment. Several supporting memoranda, analyses and data were included
in the docket for the proposed action.
The 60-day public comment period for the proposed rule closed on
July 14, 2014. In section IV of this preamble, we summarize each key
issue from the proposal, briefly summarize major comments received and
provide a response, and describe the final policy in the rule,
including any changes made to the approaches presented in the proposal.
A more detailed response to comments document can be found in the
docket for this rulemaking.
III. Summary of the Final Rule Requirements
This section provides a brief summary of the requirements of the
final rule. Further discussion of the basis for these requirements and
responses to significant comments are provided in the next section. The
EPA believes that the approach set forth in this rule directing air
agencies to gather additional data to characterize ambient air in the
vicinity of larger SO2 sources is uniquely suited for
implementation of the 1-hour SO2 NAAQS, and the Agency does
not anticipate it to be used for other NAAQS pollutants. The final rule
establishes minimum requirements for air agencies to characterize 1-
hour SO2 air quality concentrations across the country, with
an emphasis on doing so in the vicinity of sources that have the
largest annual SO2 emissions. Note that there are already
minimum SO2 ambient monitoring requirements in place that
were established when the 1-hour SO2 NAAQS was adopted. See
75 FR 35520, June 22, 2010. The requirements in the present rule
supplement those monitoring requirements, which remain in place. As
discussed in more detail in the next section, these requirements are
intended to establish a flexible yet effective program for
characterizing SO2 air quality in priority areas across the
country, given existing funding and resource constraints, and given the
particular characteristics of SO2 air pollution in the
affected areas. This final rule also reflects the fact that numerous
larger sources of SO2 across the country have in recent
years installed, and are expected to install in the near future,
additional control measures that may substantially reduce
SO2 emissions in some cases.
Under this rule, each air agency is required to submit a list to
the EPA by January 15, 2016, that identifies all sources within its
jurisdiction that have SO2 emissions that exceeded the 2,000
tons per year (tpy) annual threshold during the most recent year for
which emissions data for that source are available, plus any additional
sources and their associated areas identified by the air agency or by
the EPA as also warranting air quality characterization. (The list is a
permanent list of prioritized sources that excludes sources in areas
designated as nonattainment before January 2016 and is not altered by
designations after January 2016.) The rule requires air quality
characterization of the area associated with each listed source, and
provides two options for this characterization, namely the use of
monitoring or modeling. The final rule also provides a third option,
under which air agencies would establish a limit requiring emissions
from a listed source to be below the 2,000 tpy threshold, which, with
the concurrence of the EPA Regional Administrator, would result in that
source and its associated area not being subject to requirements for
air quality characterization. The EPA anticipates discussions with air
agencies early in 2016 to resolve any questions as to what areas
warrant air quality characterization. These discussions are intended to
address whether any additional areas (e.g., areas with clusters of
sources) warrant air quality
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characterization, whether existing monitoring networks might serve to
address air quality characterization requirements, and whether any new
limits intended by the air agencies negate the need for air quality
characterization.
For each source on the list, the air agency will be required to
indicate by July 1, 2016, whether it will characterize air quality
through ambient monitoring or through air quality modeling or,
alternatively, whether it will be subjecting the pertinent source or
sources to emission limit(s) that will keep the source(s) below this
rule's 2,000 tpy threshold. The option identified by the air agency for
each source and its associated area will determine the submittal and
timing requirements for the air agency to provide the required
information.
If the air agency chooses the first option, ambient monitoring for
a source, the air agency must include information about the planned new
monitor(s) in the annual monitoring plan that the air agency must
submit to the EPA by July 1, 2016; and the air agency must also ensure
that the new monitor(s) are operational by January 1, 2017. The
required monitors shall be sited and operated either as State and Local
Air Monitoring Stations \3\ (SLAMS) or in a manner equivalent to SLAMS.
In either case, monitors shall be subject to reporting and data
certification requirements as prescribed in 40 CFR 58.15 and 58.16
(e.g., quarterly reporting of monitoring data to the Air Quality
System, and the annual certification of data by May 1 of the following
year), and must satisfy applicable criteria in 40 CFR part 58,
appendices A, C, and E.
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\3\ The SLAMS network is an air quality surveillance system that
consists of a network of monitoring stations designated as SLAMS
which measure ambient concentrations of those pollutants for which
standards have been established in 40 CFR part 50.
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If the air agency chooses the second option, air quality modeling
for a source, it must submit a modeling protocol for each such source
to the EPA by July 1, 2016, for review and consultation with the EPA
Regional Office. The modeling analyses must then be submitted to the
EPA by January 13, 2017.
If the air agency chooses the third option, to provide federally
enforceable emissions limitations that limit emissions of an applicable
source to less than 2,000 tpy, or to provide documentation that the
applicable source has permanently shut down, the air agency must notify
the EPA of its decision by July 1, 2016, and provide a description of
the planned emission limitation, including identification of the level
of the limitation being planned. Especially in areas with multiple
sources, the limit(s) should be sufficiently low as to avert the need
for air quality characterization that applies for other listed sources.
Therefore, the rule requires the concurrence of the EPA as to whether
the limit that the air agency intends will suffice in lieu of
conducting air quality characterization. By January 13, 2017, the air
agency must provide EPA with documentation demonstrating that the
emission limits are federally enforceable, adopted, and require
compliance by January 13, 2017, in order for areas containing such
sources to avoid the need to characterize ambient SO2
emissions under the rule. If EPA approval is required to make a limit
federally enforceable, the submittal must be sent to the EPA early
enough such that the EPA has enough time to complete a rulemaking to
make the limit federally enforceable by the January 13, 2017, date.
Section IV.D of this preamble provides a discussion of selected
technical considerations related to characterizing air quality, but the
rule does not prescribe how an ambient monitoring network around an
identified SO2 source is to be designed, or how air quality
modeling must be specifically done to meet the objectives of this rule.
As stated in the proposal, the EPA has developed TADs that provide
approaches on ambient monitoring and air quality modeling when planning
and executing air quality characterization activities, and recommends
that air agencies refer to these documents to support their efforts.
For example, the TAD for ambient monitoring suggests potential options
and recommendations on different analyses and approaches that could be
considered to help the air agency site source-oriented SO2
monitors in locations of expected maximum 1-hour concentrations. The
TAD for air quality modeling explains that 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. It suggests that in order to
characterize recent air quality levels around a source, it would be
acceptable to use actual hourly emissions data, actual meteorological
data and actual stack height information as technical inputs to the
modeling analysis. However, it is important to note that, except to
require that monitoring be sited and operated in a manner equivalent to
SLAMS and to provide that modeling may be based on actual or allowable
emissions, this rule does not promulgate any specific requirements with
regard to these analytical approaches, and air agencies are expected to
use their best professional judgment, consulting as appropriate with
the EPA, in conducting these analyses. Air agencies should also contact
their respective EPA Regional Offices regarding any additional issues
beyond those addressed in the TADs.
The final rule also includes provisions specifying how
characterization requirements for listed sources continue into the
future (i.e., ongoing data requirements). For areas where air quality
is to be characterized through ambient monitoring, the rule requires
the monitoring to be conducted for the calendar years of 2017 through
2019, in order to calculate a valid design value for each area. The
rule requires that air agencies (or other parties conducting the
monitoring) continue the operation of all existing and new monitors
used to meet the requirements of this rule. However, it also provides
for the possibility that an air agency may obtain EPA approval to
terminate operation of a monitor that was established to meet the
requirements of this rule if the air quality values at the monitor are
low enough to meet specific criteria. Following commencement of
operation of a new monitor, the air agency may seek EPA approval to
terminate operation of the monitor pursuant to Sec. 51.1203(c)(3) of
this rule, if the monitored design value for the first 3-year period or
second 3-year period is no greater than 50 percent of the 1-hour
SO2 NAAQS. After the fourth year following commencement of
operation of a new monitor, the air agency may be able to seek approval
to shut down the monitor if it meets the criteria specified in existing
regulations at 40 CFR 58.14.
For areas that were characterized using air quality modeling, the
ongoing data requirement applies only where the modeling was based on
actual emissions and where the area has not subsequently received a
nonattainment designation. In such cases, the air agency will be
required to submit an annual report to the EPA providing updated
emissions information and recommending to the EPA whether further
modeling is warranted to assess any expected changes in recent air
quality. For example, it may be appropriate for the air agency to
conduct updated modeling for an area if there have been increases in
short term emissions rates, an increase in annual emissions, or changes
in facility operations. Where warranted, the air agency shall conduct
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updated modeling to characterize air quality in light of the identified
emissions changes and present the results in its annual report to the
EPA. Analogous to the monitor shutdown provisions noted earlier, the
requirement for the annual emissions assessments for an area originally
characterized by modeling may be terminated if the air agency provides
a modeling analysis demonstrating that actual emissions in the previous
year for SO2 sources in the area results in a modeled design
value that does not exceed 50 percent of the NAAQS at any receptor
within the modeling domain. While the annual assessment requirement
under this rule would be terminated in such cases, any other EPA
requirements to provide data (e.g., for the Air Emission Reporting Rule
(AERR)) would not be affected.
The EPA received more than 80 comments on the proposed rule. Taking
into consideration the range of comments received, the EPA made a
number of revisions that are reflected in the final rule, including the
following:
The source emissions threshold approach was changed to a
single 2,000 ton annual SO2 emissions level, so the final
rule does not include thresholds that vary depending on the population
of the area.
Air agencies still need to identify in January 2016 a list
of sources in their jurisdiction for which air quality is to be
characterized, but they now have until July 2016 to indicate whether,
for each source, they plan to use modeling or monitoring to
characterize air quality, or to adopt an enforceable emissions limit.
(The rule clarifies that this list would not include any source located
in an area already designated as nonattainment for the 2010
SO2 NAAQS.) The approach in the proposal would have required
the air agency to indicate its planned approach for each source in
January 2016.
The final rule also includes a set of monitor shutdown
provisions that is a hybrid of the options included in the proposed
rule and the existing monitor shutdown provisions in 40 CFR part 58. A
monitor required under this rule would be eligible for shutdown if it
has a design value less than 50 percent of the SO2 standard
during one of the first two 3-year periods of operation. After this
point in time, any potential shutdown would need to meet the basic
shutdown provisions that apply for SLAMS monitors as described in 40
CFR 58.14.
The proposal took comment on three potential approaches
for ongoing requirements for air agencies to provide modeling or
emissions data for areas that were originally characterized with
modeling based on actual emissions data. As noted earlier, the approach
in the final rule requires the air agency to provide emissions data to
the EPA annually for all sources not designated as nonattainment, and
to recommend to the EPA whether an emissions change was substantial
enough to warrant updated air quality modeling.
A number of commenters suggested that an air agency should
be able to avoid the air quality characterization requirement for a
source if it adopted a federally enforceable requirement limiting
annual emissions at the source to less than 2,000 tpy. The final rule
now includes such a provision. This type of limit would need to be
adopted and in effect by January 2017.
IV. Responses to Significant Comments on the Proposed Rule
A. The Use of Monitoring and/or Modeling Data
1. Legal Authority To Require States To Submit Data Pursuant to This
Rule
a. Summary of Proposal
In the proposed rule, the EPA explained that the requirements for
the air agency to submit the SO2 monitoring and modeling
data described in Sec. 51.1203 of the proposed rule are appropriate
steps needed to understand SO2 air quality throughout the
country, and are consistent with section 110(a)(2)(B), section
110(a)(2)(K) and section 301(a)(1) of the CAA. See 79 FR 27457, May 13,
2014.
b. Brief Summary of Comments
Some state commenters asserted that the DRR modifies the CAA and
imposes new monitoring and modeling obligations on air agencies. One
commenter suggested that requiring states to develop monitoring or
modeling data in accordance with this proposal modifies the statutory
mandate to designate all areas by June 2013 because the EPA intends to
use these data for designations. One industry commenter stated it is
not appropriate to replace the CAA's statutory directive for
designations with extra-statutory provisions like those proposed in the
DRR.
Several state and industry commenters stated that the proposed
requirements and schedules conflict with requirements that apply to the
EPA to timely complete designations under section 107 of the CAA. These
commenters stated that the CAA required the EPA to make area
designations under the new SO2 standard no later than June
3, 2013, and that the EPA failed to comply with that mandatory
obligation. Therefore, the commenters claimed, the DRR proposal's
discussion of a schedule for issuing designations by December 2020 is
beyond the EPA's authority. One state commenter cited EME Homer City
Generation LP v. Envt'l Prot. Agency, 696 F. 3d 7, 27 (D.C. Cir. 2012)
and stated that the DRR cannot stand as proposed because it fails to
follow the mandatory timelines for promulgating area designations, and,
therefore, exceeds the EPA's statutory authority.
c. EPA Response
The comments that assert that the EPA has not designated areas
under the 2010 SO2 NAAQS in a timely manner are beyond the
scope of this rulemaking, and are not germane to the issue of the EPA's
statutory authority to direct air agencies to conduct monitoring or
modeling to further characterize ambient air concentrations of
SO2. Through this rulemaking, the EPA is not establishing or
modifying any area designation requirements provided for in section 107
of the CAA, nor does any aspect of this final rule conflict with any
provision of section 107 that directs states and the EPA to take timely
action to issue designations. The purpose and effect of this rulemaking
is to require air agencies to characterize air quality in priority
areas throughout the country where existing ambient monitors may not be
adequately characterizing peak 1-hour SO2 ambient air
concentrations. The air quality data obtained as a result of this
rulemaking then may be used in future analytical actions by the EPA,
including designations of any undesignated areas or redesignations of
already designated areas. It is true that in the proposed rule preamble
we discussed how the timing of the implementation of this rule would
fit with our intended schedule for completing area designations, but
the proposal did not itself purport to establish a binding schedule for
completing designations.
The EPA notes that litigation was filed against the EPA to compel
the Agency to complete designations under CAA section 107, and on March
2, 2015, the court in one of those cases issued a ruling that places
the EPA on a binding schedule to complete area designations for the
2010 1-hour SO2 NAAQS. See, Sierra Club, et al. v. McCarthy,
Case No. 13-cv-03953-SI (N.D. Cal., March 2, 2015) (Order Granting
Joint Motion To Approve And Enter Consent Decree And Denying Other
Motions As Moot; and Consent Decree). Copies of the court's order and
the March 2015 consent decree setting forth the EPA's schedule
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for completing designations have been placed in the docket for this
rulemaking. Under the schedule ordered by the court, the EPA is
required to complete the designations in no more than three future
rounds.
First, by July 2, 2016 (16 months from the date of the court's
order), the EPA must sign a notice for publication in the Federal
Register that promulgates designations for remaining undesignated areas
that: (a) Based on air quality monitoring in the three full calendar
years preceding that date have monitored violations of the NAAQS; or
(b) contain any stationary source that has not by March 2, 2015, been
``announced for retirement'' and that, according to data in the EPA's
Air Markets Database, either (1) emitted more than 16,000 tons of
SO2 in 2012, or (2) emitted more than 2,600 tons of
SO2 and had an annual average emission rate of 0.45 lbs.
SO2/Mmbtu or higher in 2012. (The March 2015 consent decree
defines ``announced for retirement'' as meaning ``any stationary source
in the United States with a coal-fired unit that as of January 1, 2010,
had a capacity of over five (5) megawatts (MW) and that has announced
it will cease burning coal at that unit through a company public
announcement, public utilities commission filing, consent decree,
public legal settlement, final state or federal permit filing, or other
similar means of communication.'')
Second, by December 31, 2017, the EPA must sign such a notice
promulgating designations for remaining undesignated areas in which, by
January 1, 2017, states have not installed and begun operating a new
SO2 monitoring network meeting EPA's specifications
referenced in this rulemaking. Finally, by December 31, 2020, the EPA
must sign a notice promulgating designations for all remaining
undesignated areas.
The EPA notes that the schedule imposed by the court will allow at
least the latter two stages of designations to be informed and
benefited by the additional information that is timely obtained
pursuant to this final rule, as appropriate. However, we also note that
the round of designations that is required to be completed by July 2,
2016, will likely be conducted before state air agencies and the EPA
will have been able to implement this final rule, and will instead rely
upon data and information that is separately developed or obtained
during the designations process. Nevertheless, as explained later in
this document, depending on how those areas become designated in 2016,
the rule may still result in additional information that could inform
future assessments of attainment status for such areas.
The EPA continues to believe that the requirements of this rule for
air agencies to submit a list of sources where further air quality
characterization is needed, and the other data submittal requirements
found in Sec. 51.1203 of this rule, are appropriate steps needed to
better understand SO2 air quality throughout the country,
and are consistent with section 110(a)(2)(B), section 110(a)(2)(K), and
section 301(a)(1) of the CAA. The commenters did not challenge this
view. Section 110(a)(2)(B) indicates that State Implementation Plans
(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 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.'' 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 EPA often establishes and revises monitoring requirements for
implementing NAAQS. Those requirements will not necessarily always
generate new information in time to inform timely area designations
under CAA section 107. See, e.g., 75 FR 81126, 81130, December 27,
2010. The validity of such rules does not depend upon whether
information generated pursuant to those requirements will be gathered
in time to support designations that are timely under section 107.
Here, the commenters have raised no objection to the central premise of
the rule, which is that additional information that better
characterizes air quality near larger sources of SO2 is
warranted and is authorized to be required under sections 110 and 301
of the Act. Irrespective of when the EPA uses this information--for
example, irrespective of whether the EPA promulgates initial
designations of ``unclassifiable'' (and then uses the information
collected pursuant to this data requirements rule in later
redesignations), or whether the EPA promulgates the remaining
designations after the information required here becomes available--the
EPA believes that this rule is authorized and is warranted. Therefore,
in this final rulemaking, the commenters have provided no basis for the
EPA to not require air agencies to submit such SO2
monitoring and modeling data to the EPA, as proposed. The final rule is
fully consistent with the Agency's broad authority under section 110
and 301, as well as with the EPA's authority under CAA section
114(a)(1) to direct any person to provide information as is reasonably
required to improve characterization of ambient air quality near larger
sources of SO2.
2. Legal Authority To Base Air Quality Evaluations on Modeling Data
a. Summary of Proposal
In the proposal, the EPA stated that existing air quality modeling
tools are technically sound and historically have been used to
characterize SO2 air quality when monitoring data were not
available; therefore, the EPA considers these modeling tools
appropriate for assessing air quality impacts from SO2
emissions. The EPA stated that historical use of modeling to
characterize SO2 air quality concentrations has been
affirmed as technically valid and lawful under the CAA by reviewing
courts. See 79 FR 27448, May 13, 2014.
b. Brief Summary of Comments
Some industry group commenters stated that the DRR provisions
allowing for modeling to characterize ambient SO2
concentrations go beyond what is necessary to comply with the CAA,
arguing that 40 CFR 50.17 provides that monitoring is the sole basis
for determining attainment. Commenters stated that the precise wording
of 40 CFR 50.17 establishes ambient air monitoring as the only basis
for determining if the SO2 NAAQS is being met because it
specifies that:
(a) The level of the national primary 1-hour annual ambient air
quality standard for oxides of sulfur is 75 parts per billion (ppb,
which is 1 part in 1,000,000,000), measured in the ambient air as
SO2.
(b) The 1-hour primary standard is met at an ambient air quality
monitoring site when the 3-year average of the annual (99th percentile)
of the daily maximum 1-hour average
[[Page 51057]]
concentrations is less than or equal to 75 ppb, as determined in
accordance with appendix T of this part.
(c) The level of the standard shall be measured by a reference
method based on appendix A or A-1 of this part, or by a Federal
Equivalent Method (FEM) designated in accordance with part 53 of this
chapter.
One public interest group commented that the provisions in the
proposed DRR for conducting modeling are consistent with the EPA's
historic use of air dispersion modeling for multiple NAAQS
implementation purposes. This public interest group stated that
dispersion modeling has a lengthy history as an appropriate tool for
use in SO2 designations and other actions, and provided
several references to the EPA's documents and to court rulings to
demonstrate that historic use.
In contrast, without disputing the fact that the EPA has often
relied upon modeling to inform decisions implementing the
SO2 NAAQS, several state and industry commenters stated that
monitoring, not modeling, has historically been used for designation of
areas as attainment or nonattainment under this and other NAAQS.
Several industry commenters supported the EPA's use of notice-and-
comment rulemaking through the DRR to address certain major issues,
including the use of monitoring and/or modeling to characterize air
quality and make remaining area designations.
c. EPA Response
This final rule does not make any decisions or determinations
regarding whether any area is in fact meeting or not meeting the NAAQS
based on either monitoring or modeling information. Those decisions
will be made in separate future actions, or have already been made for
some areas in prior actions. See e.g., 78 FR 47191, August 5, 2013.
Therefore, this final rule does not take final action on the issue of
whether it is permissible to implement the commenter's previous quoted
provisions of 40 CFR 50.17(a)-(c) based on a combination of both
monitoring and modeling information where both are available, or
exclusively on modeling information where appropriate modeling
information is available and monitoring is not. The commenters'
objections appear to focus on how future-gathered information resulting
from the rule may or can be used in subsequent NAAQS implementation
actions, but the focus of this rule is on the initial gathering of the
information itself. In future designation, redesignation, or other
implementation actions, commenters may raise their objections to the
validity of information that the EPA relies upon in those specific
actions, but such objections are beyond the scope of this final rule.
The commenters appear to be raising objections that were also
raised after the EPA's promulgation of the 2010 SO2 NAAQS,
in response to the EPA's final rule preamble discussion explaining the
Agency's then-intended implementation approach under the NAAQS. In
their petitions for judicial review of the NAAQS, several states
claimed that the EPA's discussion of the intended use of modeling in
NAAQS implementation contravened the regulatory text of Sec. 50.17.
However, noting that the petitioners' claims addressed potential final
implementation actions that had not yet in fact occurred, the U.S.
Court of Appeals for the D.C. Circuit dismissed the petitioners' claims
without addressing their merits, or lack thereof. See National
Environmental Development Association's Clean Air Project v. EPA, 686
F.3d 803 (D.C. Cir. 2012). Likewise here, the EPA is not yet taking any
action to apply modeling regarding any decision of whether an area is
or is not meeting the NAAQS.
In any event, we note that although 40 CFR 50.17(a)-(c) very
clearly sets forth the criteria for determining whether the NAAQS is
met at a monitoring site, it does not by its terms restrict how such
decisions may be made more broadly in areas impacted by SO2
sources, including areas where there are no monitoring sites or where
monitors are not sited at the point of maximum ambient concentration.
Indeed, it is the relative scarcity of such monitors that has caused
the EPA to undertake this rulemaking to enable states and the Agency to
better understand just what the ambient air impacts are from larger
sources of SO2, which may not be captured by the current
limited monitoring network. It is true that 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 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 35551, June
22, 2010.
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 that 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 atmospheric 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, October 5, 1978.
3. The Use of Monitoring and/or Modeling for Making Decisions About Air
Quality
a. Summary of Proposal
In the proposed rule, the EPA explained that the current ambient
SO2 monitoring network, on the whole, 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. The EPA
stated that, 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. However, the EPA noted that some areas may not be
conducive to modeling, and for such areas the EPA encouraged air
agencies to consider using enhanced monitoring to characterize air
quality. See 79 FR 27448, May 13, 2014.
b. Brief Summary of Comments
Several state and industry commenters supported the provision in
the proposed rule allowing air agencies to have the option to use
modeling and/or monitoring to characterize SO2 ambient air
concentrations, as it provides appropriate flexibility for both the
states and affected sources. Several commenters supported the EPA's
observation that modeling may not be appropriate for all SO2
evaluation scenarios, and supported the ability of
[[Page 51058]]
states to choose to evaluate NAAQS attainment through either dispersion
modeling or ambient monitoring. However, several state and industry
commenters cautioned that monitoring data should be the primary basis
for such decisions, especially designating nonattainment areas. Several
commenters claimed that, as modeling is frequently affected by factors
such as emissions inputs, meteorological data and local geography, it
is not as accurate or reliable as real-time, multiple-year monitoring.
Other commenters claimed that modeling is advantageous because it
characterizes air quality in all directions around a source with
appropriate accuracy and can be done with less expense than ambient
monitoring, which only characterizes air quality at a single location.
Some industry commenters suggested the text of proposed Sec. 51.1201
be revised to state that monitoring is the EPA's preferred analytical
approach under the rule.
c. EPA Response
The EPA agrees with commenters who stressed the need to give air
agencies the option to characterize SO2 ambient air quality
through either enhanced monitoring or modeling, and the EPA is
maintaining that approach in this final rule. The EPA believes that the
commenters have not presented any persuasive reasons for changing the
basic positions previously discussed in the preamble to the final rule
of the 2010 SO2 NAAQS rulemaking, the February 2013 Strategy
Paper, or in the proposed rule for why both air quality modeling and
ambient monitoring are appropriate tools for characterizing ambient air
quality for purposes of informing future decisions to implement the
SO2 NAAQS. However, as explained earlier, in this final rule
the EPA is not taking final action to make any determinations regarding
any area's status with respect to attaining or not attaining the NAAQS,
but is only prescribing criteria and a process for how and when air
agencies are to gather and provide to the EPA additional needed
information. How the information is used in subsequent actions
evaluating the attainment status of specific areas will depend upon the
information that air agencies collect in the future and what it shows
about areas' ambient air quality.
B. Source Coverage and Emission Threshold Options
1. Summary of Proposal
In the proposal, the EPA recognized that the characterization of
air quality in areas around more than 20,000 SO2 sources
nationally would not be feasible. The proposal stated that the key
objective to be achieved by using SO2 source emission
thresholds would be to focus the limited available resources at the
state, tribal, local and federal levels toward characterizing air
quality in areas having the largest SO2 emitting sources due
to the fact that larger sources can be expected to be the most likely
potential contributors to violations of the SO2 NAAQS. The
EPA stated in the proposed rule that, just as NAAQS ambient monitoring
networks are designed to measure air quality in areas meeting specific
criteria where the public is likely to be exposed and violations may be
likely to occur, the SO2 annual emission threshold options
in the rule are designed to meet a similar objective. See 79 FR 27453,
May 13, 2014.
In considering how to develop effective options for identifying the
minimum set of sources around which states would be required to
characterize ambient air quality, we considered three important issues
and requested comment on each:
--What would be an appropriate emissions metric for identifying
sources?
--Should the threshold options require characterization of smaller
sources in areas with higher populations?
--What would be an appropriate threshold for identifying sources near
which air quality is to be characterized?
The notice of proposed rulemaking also addressed a number of
additional elements of the implementation of these thresholds. In the
discussion below, the EPA summarizes these additional proposed
features, summarizes comments on these proposed features, and describes
the EPA's responses. Note that this section is structured so that all
the issues related to emissions thresholds are presented together
before proceeding to the comment summaries on these issues, and then to
the EPA's responses and final decision.
a. Emissions Metric: What would be an appropriate emissions metric for
identifying sources?
The proposal presented a discussion about what emissions-related
metric would be most appropriate for this rule. The proposal noted that
for the 1-hour SO2 NAAQS, the ideal metric for identifying
sources near which air quality is to be characterized would be a 1-hour
SO2 emissions rate. However, the EPA observed that while 1-
hour SO2 emission rate data are available for most
electricity generating units (EGUs) because they operate continuous
emission monitors, many non-EGUs do not operate continuous emission
monitors on all emission points and produce 1-hour data. For this
reason, the proposal stated that the emissions threshold options
presented in this rulemaking should be expressed in terms of annual
emissions of SO2 because annual emissions information is
readily available for all large SO2 sources.
The EPA requested 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 around which further ambient air quality
characterization with respect to the 1-hour SO2 NAAQS might
be required. The EPA also requested 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 any alternative factor for all SO2 sources
nationally, the time and resources needed to develop a database for
this alternative factor, any associated technical analysis and
rationale for using these other factors in defining source thresholds.
See 79 FR 27454, May 13, 2014.
b. Should the threshold options require air quality characterization
near smaller sources in areas with higher populations?
In the proposed rule, the proposed emissions threshold option and
the other two options on which the EPA requested comment each had a
``two-pronged'' form. Each potential option was expressed with a higher
emissions threshold for identifying sources located outside of CBSAs
with a population equal to or greater than 1 million persons, and a
lower emissions threshold for identifying sources located within such
CBSAs. The reasoning given for this proposed approach was that a lower
threshold for urban sources could help increase public health
protection because there are more people in an area that could be
impacted by relatively smaller sources. The EPA requested 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 requested comment on whether to
include a population exposure-based threshold at all; and on whether
alternative, or additional, criteria would
[[Page 51059]]
be appropriate to further focus resources on characterizing air quality
in areas with a higher likelihood of population exposure. See 79 FR
27455, May 13, 2014.
c. What is an appropriate threshold level or levels for identifying
sources near which air quality is to be characterized?
The EPA proposed one preferred option and took comments on two
additional options. Option 1 (proposed preferred option) would require
ambient air quality characterization around any source with annual
emissions greater than 1,000 tpy and which is located within a 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. Option 2 would require ambient air quality characterization
around sources with emissions greater than 2,000 tpy that are located
within any CBSA 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. 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.
The EPA requested comment on the preferred option and the other two
options described in the proposal. The EPA also requested comment on
any possible alternatives that might be appropriate for consideration.
The EPA requested comment on the scope of sources for which we would
require data. In addition, the EPA also requested any information
identifying sources that would be identified by these options but that
have confirmed documentation to show that they will shut down in the
next several years.
d. Discretion for Air Agencies and the EPA To Address Additional
Sources
The EPA noted in the proposed rule that, in addition to meeting the
requirements to provide information regarding areas with sources over
the future promulgated thresholds, there may still be situations where
an air agency would need to characterize air quality for other sources
below the thresholds; specifically, where the air agency, or the EPA
Regional Administrator, determines that they may have the potential to
violate the NAAQS. Application of air quality characterization
requirements was noted to be possibly warranted, for example, where
multiple smaller sources located in close proximity may collectively
exceed the emissions thresholds and/or cause or contribute to NAAQS
exceedances. See 79 FR 27455, May 13, 2014.
2. Summary of Comments
This section provides a brief summary of comments received on each
of the four source threshold issues identified previously, as well as
additional features of the EPA's proposed implementation of thresholds.
a. Comments on an Appropriate Emissions Metric
Most commenters that addressed the emissions metric issue supported
using annual SO2 emissions (in tpy) as the appropriate
metric for defining source thresholds. Several commenters stated that
it is most appropriate to evaluate annual emissions since these data
are widely reported to the EPA and are readily available. Some industry
commenters stated that using an annual emissions based threshold
approach for identifying areas to be evaluated would serve to make more
manageable the demands on state, tribal, local and federal resources.
Several other commenters stated that the use of additional factors such
as stack height, 1-hour SO2 emission rate, proximity to
sensitive populations, and topography would make the source
identification process unnecessarily difficult and time consuming. On
the other hand, a few regulatory agency commenters urged the
establishment of supplemental criteria based on short-term spikes in
emissions.
b. Comments on Whether the Options Should Require Characterization Near
Smaller Sources in Areas With Higher Populations
A number of state and industry commenters supported the application
of a lower emission threshold in urban areas. Some commenters stated
that population centers represent locations of higher potential public
exposure and, therefore, characterization of air quality in these areas
would be more representative of the public's SO2 exposure
risk. Several state and industry commenters stated that a threshold
approach based purely on emissions could inappropriately focus limited
resources on areas with limited to no public exposure. Some state
commenters noted that, as a precedent, a population threshold has been
used to establish the minimum monitoring requirements for the
SO2 NAAQS as well as the NAAQS for nitrogen dioxide, carbon
monoxide, and particulate matter.
Some commenters stated that many sources located within an existing
CBSA are located on the edge of the boundary in less populated areas
and urged the EPA to consider more refined census data based on
population density. One industry commenter suggested, for example, that
the EPA could use population density data around the affected
facilities out to a radius of 10 kilometers (km) and, if average
population density from the 2010 census in this area exceeds a certain
threshold (e.g., 100 persons/square km), then the lower emissions
criteria would be used. Some tribal commenters, some environmental
group commenters, and some state commenters recommended against
applying different thresholds in less populated areas, in order to
assure that all areas are equally protected against violations of the
air quality standard.
c. Comments on Source Threshold Options
One public interest group and several states urged the EPA to adopt
the proposed Option 1 level of 1,000 tpy, but apply it uniformly,
regardless of population in order to ensure a basic level of health
protection to people who live around the sources. Some commenters
stated that because modeling has shown that sources with emissions
below 2,000 tpy have the potential to cause or contribute to modeled
NAAQS violations, an emissions threshold of 1,000 tpy is more
appropriate to ensure that air quality characterizations are accurately
capturing potential NAAQS violations.
Several state and industry commenters supported Option 2 stating it
balances limited agency resources for the implementation of this rule
while still allowing important SO2 emission source areas to
be evaluated. Some industry commenters stated Option 2 appears to be
the best option because the difference between the number of sources
captured by Options 1 and 2 is substantial while the difference in
overall emissions covered by the two options is small.
Numerous state and industry commenters supported Option 3, stating
it would apply reasonable thresholds without burdening states with
unnecessary modeling or monitoring. One industry commenter stated that
this option would allow states to focus their limited resources on the
areas with the largest 211 sources of SO2 emissions.
One industry commenter stated that if the EPA decides that either
Option 1 or 2 is preferable, then the source
[[Page 51060]]
threshold needs to be revised to take into account the following
additional factors: The distance a source is located from population
centers in general and sensitive populations in particular; stack
heights; topography and meteorological factors unique to the source(s);
and economic conditions that will affect a source's expected
SO2 emissions. This commenter disagreed with the proposal's
statement explaining why the Agency does not believe it necessary for
air agencies to consider such factors, stating that the lack of a
nationwide database with respect to such factors is irrelevant since
the modeling is to characterize localized ambient air quality.
d. Comments on Discretion To Address Additional Areas
Several state and tribal commenters requested clarification of
criteria the EPA would use to determine additional areas to be
characterized beyond those with sources emitting more than the
applicable threshold. A few commenters offered specific
recommendations, for example to characterize areas of 10 km or 25 km
diameters in which total emissions exceed the threshold but those of no
single source exceeding the threshold. A few commenters recommended
that the EPA should not have the discretion to subject additional areas
to characterization unless total emissions in the areas exceed the
applicable threshold. Some commenters recommended that the rule specify
criteria to be used to identify multi-source areas that would need to
be characterized. Conversely, some commenters recommended that the EPA
not codify any specific criteria, recommending instead that the EPA
provide guidance on how it envisions addressing areas with multiple
sources and rely on the professional judgment of air agency personnel
in consultation with the EPA to identify specific additional areas that
warrant being characterized. Also, one state commenter recommended that
any area ``that, based on the state's knowledge, has the potential to
exceed the NAAQS'' should become subject to requirements for air
quality characterization. Finally, a few industry commenters and a few
state commenters urged that the EPA not have the discretion to subject
additional areas to DRR requirements.
3. EPA Response
The EPA considered the many and varied comments received on the
source threshold options presented in the proposal. After considering
the comments received and as explained below, the EPA has decided to
establish a requirement for air agencies to identify all sources with
annual SO2 emissions that exceed 2,000 tpy (using emissions
data from the most recent calendar year for which such data are
available) and characterize air quality around such sources according
to the timeline in section IV.C of this preamble. The following
subsections also address the other comments relating to applicability
of the requirements for air quality characterization described
previously.
a. Emissions Metric
The EPA agrees with the many commenters who expressed support for
using an annual emissions metric because annual emissions data are most
readily available for all large SO2 sources, whereas 1-hour
emissions rate information is not readily available for all
SO2 sources. Since the tpy emissions metric is a common
denominator in the emissions inventory and reporting universe, the EPA
believes that the use of this metric is most appropriate to be required
under a rule that applies broadly to areas with sources that do not
already measure 1-hour emissions rates. Using tpy will provide air
agencies and the regulated community a common, easily verifiable,
straightforward approach for identifying sources around which air
agencies are required to characterize air quality. This approach will
rely on existing emission inventory collection systems that are already
in place. An approach based on tons of emissions per year also should
reduce unforeseen or otherwise uneven application of the requirements
for air quality characterization that could arise if different metrics
are used for different SO2 source sectors to identify areas
for which air agencies are required to characterize air quality.
The EPA acknowledges that some state commenters suggested inclusion
of a 1-hour emissions rate-based criterion for identifying certain
sources with infrequent, episodic SO2 emissions at
atypically high rates that could impact nearby populations. The EPA
notes that the emissions threshold included in the final rule
establishes only minimum requirements for identifying sources. The EPA
agrees with state commenters who recommended that air agencies should
also characterize areas that, based on their knowledge of sources and
areas, may be at risk of violating the standard. Thus, under this rule
air agencies could also require characterization of air quality near
sources prone to episodic emissions with relatively high rates or
amounts, as appropriate. However, because short-term emissions data are
not available for all SO2 sources, the EPA did not include
in this rule a minimum requirement for identifying source areas needing
air quality characterization based on this metric.
b. Characterization Near Smaller Sources in Areas With Higher
Populations
The EPA considered the comments received on the issue of whether a
lower emissions threshold should be included for areas with more dense
populations (e.g., CBSAs greater than 1 million population). A number
of commenters appeared to interpret the inclusion of a lower threshold
for areas with higher population as being less protective of the public
in less populated areas. The EPA wants to clarify that this was not the
intention behind the population-inclusive options included in the
proposed rule. The SO2 NAAQS, and all NAAQS, are intended to
provide equal protection for citizens throughout the country. The
proposed use of both population and emissions thresholds as a means to
require air quality characterization was simply one approach to focus
limited federal and state modeling and monitoring resources into
characterizing locations where a greater coincidence of people and
SO2 emissions occur, and thus a potentially greater
potential for exposure is presented. After reviewing the comments on
this issue, however, the EPA has decided not to move forward with the
proposed preferred approach, and instead to apply requirements for air
quality characterization based on emissions levels uniformly across the
country for both more urbanized and less urbanized populations so as to
focus primarily on the size of the sources.
It should be noted here that any monitoring that occurs pursuant to
this rulemaking is potentially in addition to, or can possibly help to
satisfy, required SO2 monitoring stemming from 40 CFR part
58, appendix D, section 4.4. Those monitors required in 40 CFR part 58,
appendix D, section 4.4 are determined using a unique metric that
accounts for the coincidental occurrences of SO2 emissions
and population, namely the Population Weighted Emissions Index (PWEI).
This rulemaking does not supplant or otherwise modify those existing
requirements.
c. Emissions Threshold
Regarding the comments EPA received expressing preferences on the
proposed emission threshold options, the EPA notes the wide range of
views. A few commenters recommended alternate thresholds in the range
from 1,000 tpy to 10,000 tpy, or
[[Page 51061]]
recommended pairs of thresholds within this range. Some commenters
provided modeling analyses as an indication that sources larger than
12,000 tpy did not cause a violation of the standard, while other
commenters recommended a single emissions threshold of 1,000 tpy and
provided modeling analyses of different sources as an indication that
sources less than 2,000 tpy caused modeled violations. These comments
demonstrate that ambient SO2 impacts can be variable, and
are dependent on many factors other than annual emissions (such as
meteorology, stack height, local topography and plant operations).
These factors can only be assessed through analytical approaches, such
as ambient monitoring or air quality modeling, which take many of these
related factors into account simultaneously. These comments demonstrate
why air quality characterization of the area around these sources is
needed to protect public health in the first place.
The EPA believes that, for the purposes of establishing a minimum
threshold that prioritizes the resources that will be devoted to
characterizing air quality near SO2 sources nationally, the
2,000 tpy source emissions threshold strikes a reasonable balance
between the need to characterize air quality near sources that have a
higher likelihood of contributing to a NAAQS violation and the
analytical burden on air agencies. This threshold is on the lower end
of the range of thresholds recommended by commenters because sources on
the lower end of the range have the potential to cause or contribute to
violations of the NAAQS. As compared to the preferred option in the
proposal (i.e., 1,000 tpy sources in CBSAs over 1 million people; 2,000
tpy sources not in CBSAs over 1 million people), the 2,000 tpy
threshold would mean that, in the aggregate, air agencies would need to
address air quality near about 35 fewer sources (or 7 percent fewer).
Nevertheless, the total emissions addressed would still account for 89
percent of the SO2 emissions nationally (based on 2011
emissions), very close to the 90 percent level that has been considered
to be reasonable by many stakeholders in the past.\4\ National
SO2 emissions have declined by a significant amount from
2011 to 2013 (around 1.5 million tons, or more than 20 percent), for
various reasons. The EPA assessed the number of sources meeting a 2,000
tpy threshold based on 2013 emissions data now available for EGUs and
2011 emissions data for non-EGUs. Compared to the assessment in the
proposal, which assessed the number of sources meeting the proposed
threshold (1,000 tpy in urban areas/2,000 tpy elsewhere) based solely
on 2011 data, the EPA now estimates that approximately 70 fewer sources
(about 15 percent) will need nearby air quality to be characterized
than was estimated in the proposal. Based on the updated data, the EPA
estimates that already-designated sources plus sources currently
exceeding the final threshold in this rule still would account for 86
percent of national emissions. Under this rule, each air agency will be
required to identify all sources with annual SO2 emissions
that exceed 2,000 tpy (using emissions data from the most recent
calendar year for which such data are available) and characterize air
quality around such sources according to the timeline in section IV.C
of this preamble.
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\4\ 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.
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Of course, if the trend in reduction of SO2 emissions
continues at individual sources, there will also be a corresponding
reduction in national emissions, and both kinds of reductions are
desirable for improving public health, even if that results in fewer
source areas becoming subject to the emissions characterization
requirements in the final rule. Conversely, if the trend reverses and
source emissions increase, more sources and areas will be required to
be characterized under the rule. Thus, the exact number of sources and
areas that will exceed the promulgated threshold when air agencies
begin characterizing areas under the rule cannot be precisely known at
this time, nor can their future percentage share of the national
inventory be precisely estimated. Nevertheless, the EPA believes that
the promulgated threshold strikes a reasonable balance based on the
information the Agency currently has regarding recent historical
SO2 emissions inventory levels. An analysis of potential
source threshold options and associated source coverage, emissions
coverage, and analytical costs is included in an EPA memorandum to the
docket for this rule.\5\
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\5\ See also: ``Analysis of Source Threshold Options for the
Final SO2 Data Requirements Rule,'' memorandum to docket
EPA-HQ-OAR-2013-0711, July 16, 2015.
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d. Discretion To Address Additional Areas
Section 114(a)(1) of the CAA already provides the EPA authority and
discretion to require emissions sources to install, use and maintain
monitoring equipment and provide other information as the Agency may
reasonably require, even in the absence of this DRR. In addition, the
EPA had several reasons for proposing as part of this rule to reinforce
state and the EPA discretion to also require air quality
characterization around sources with emissions below the proposed
thresholds. The purpose of proposing the use of emission levels as the
criterion for determining applicability of the air quality
characterization requirement is that emissions provide a simple means
of identifying the sources that are most likely to cause or contribute
to violations of the SO2 NAAQS. Nevertheless, the EPA
recognizes that a variety of factors other than emission levels can
influence the likelihood of NAAQS violations. As one example, source
characteristics such as stack height and plume buoyancy can
significantly affect source impacts. As another example, clusters of
multiple smaller sources that are in close proximity can cause as much
impact as a single larger source. Finally, the EPA recognizes that a
variety of other reasons may exist that may warrant further
characterizing air quality in particular areas, which supports
maintaining state and EPA Regional Administrator discretion to require
air quality characterization in the area. The EPA continues to believe
that states and the EPA should retain this authority and that it would
be unreasonable to restrict implicitly, via this rule, the inherent
authority that air agencies already have to require sources of air
pollution to measure their emissions and characterize their impacts.
For these purposes, the EPA continues to believe that the rule
should make clear that states and the EPA retain the discretion to
subject additional areas to the requirements for air quality
characterization beyond areas with a single source exceeding the
emissions threshold. The use of a simple emission threshold in the rule
provides a convenient means of administering the application of the
requirements for air quality characterization for the majority of
cases. However, the impacts of a given level of emissions vary
substantially, such that many areas with a source or sources that do
not exceed the emission threshold might be known to have a high risk of
contributing to NAAQS violations, potentially resulting in a higher
risk of NAAQS violations than other areas exceeding the emission
threshold. As a result, a rule that sets forth minimum requirements
based on
[[Page 51062]]
an emissions threshold cannot reasonably be used to support an
assumption that no further characterization near smaller sources is
warranted, or to preclude authority that air agencies already have to
investigate the impacts of such sources. Therefore, while this rule
requires the air quality characterization near the above-threshold
sources, the EPA and air agencies will also need to consult regarding
the need for the characterization of air quality near sources below the
threshold as well.
Among cases in which no single source meets the applicable emission
threshold, no simple indicator is available to indicate which of these
cases warrants air quality characterization. For areas with a single
source, the areas could warrant air quality characterization if the
stack height is low, if the plume rise is minimal, if terrain or
meteorology is conducive to high impacts, and/or if emissions are just
slightly below the threshold. For areas with multiple sources,
concentrations are influenced not only by these stack, terrain and
meteorological factors but also by the level of emissions at each
source, the distances between them and the wind directions in the
nearby area. The EPA appreciates the comments urging the establishment
of specific criteria in the rule for identifying additional areas that
warrant air quality characterization, but the EPA finds that these
areas are better identified on a case-by-case basis reflecting a
judgment considering the range of factors that influence the likelihood
of NAAQS violations. That is, the EPA agrees with the state commenter
urging that the rule provide for discretionary coverage of additional
areas, such that additional areas that in the air agency's (and the
EPA's) judgment have significant potential for violating the NAAQS can
be made subject to requirements for air quality characterization on
case-by-case bases.
Consequently, the EPA is retaining the discretion for air agencies
and the EPA to require additional areas to be characterized beyond
those with a source exceeding the emission threshold. However, the EPA
is not revising the rule to establish specific criteria for identifying
such areas; the EPA is instead relying on case-by-case evaluation of
the various relevant factors to determine which additional areas
warrant air quality characterization.
For areas with multiple sources, the EPA recognizes that a number
of such areas may have no single source that exceeds the threshold
discussed earlier and yet may have concentrations similar to other
areas with a single source exceeding the threshold. Commonly, such
areas would have multiple sources clustered in relatively close
proximity and would have total emissions at or above the threshold. The
EPA envisions the air agencies and the EPA evaluating multiple source
areas on a case-by-case basis to determine whether the areas warrant
the same priority as areas where a single source has emissions above
the threshold. Generally, the EPA strongly recommends that areas with
multiple sources, where the combined impact would be expected to be as
much as the impact of a typical single source emitting at least 2,000
tpy, should be carefully considered for air quality characterization,
and we expect the EPA Regional Administrators to focus on such areas in
exercising their discretion. As stated previously, a rule that sets
forth minimum requirements based on an emissions threshold cannot also
be reasonably used to support an assumption that no further
characterization near smaller sources may be required. Therefore, in
addition to requiring air quality characterization near sources above
the emission threshold, the rule also preserves the discretion of the
EPA and air agencies to require air quality characterization in
additional areas, which will necessitate consultation on a case-by-case
basis regarding the need for characterization of additional areas
beyond those containing a source exceeding the threshold in this rule.
Regarding the comments recommending specific criteria for
subjecting multiple source areas to the requirements for air quality
characterization, the EPA believes that too many factors influence the
combined impact for the EPA to establish a single set of criteria for
determining whether each area warrants becoming subject to the
requirements for air quality characterization. Nevertheless, for the
EPA and state agencies considering using their discretion to require
characterization of additional areas, the EPA believes that the
recommendations of these commenters provide good suggestions for where
to begin making such decisions, to be followed by a case-by-case
judgment as to the expected degree of combined impacts.
In numerous cases, areas include multiple operations that
previously were all part of a single source that now for business
reasons have subdivided their ownership, such that the operations that
previously were a single source must now be considered multiple
sources. For example, in many cases, where previously the area had a
single integrated iron and steel mill, the iron- and steel-making
operations now have separate ownership from the coke-making operations,
such that the former single source has now become two sources. In these
cases, an additional equity concern arises, that otherwise comparable
facilities should not be treated differently based on a business
decision that has no effect on air quality. If the combined emissions
of these now separately-owned operations exceed 2,000 tpy, the impact
would commonly be similar to the impacts of single facilities emitting
over 2,000 tpy, and such groups of separately owned operations would
thus warrant air quality characterization.
Regarding the commenters who recommended that the EPA stipulate
that an area with multiple sources emitting less than the threshold
should not be required to characterize air quality under the rule
unless the combined emissions exceed the threshold, the EPA does not
agree with this approach. Even for single source areas, the EPA is
preserving the discretion air agencies and the EPA already have to
require air quality characterization where the source emits less than
the threshold but where concern about potential NAAQS violations
warrants further air quality characterization. By the same logic, the
combined impacts of multiple sources may warrant further
characterization even if the combined emissions are less than the
threshold.
C. Data Requirements and Program Implementation Timeline
1. Overall Timeline
a. Summary of Proposal
In the proposed rule, the EPA proposed an implementation timeline
addressing feedback and concerns raised in previous stakeholder
meetings, which the EPA considered to provide air agencies with
sufficient flexibility and time to pursue either improved monitoring or
modeling to characterize air quality. The EPA designed the schedule to
allow air agencies to account for SO2 reductions that will
occur over the next several years as a result of implementation of
national and state level programs and facility decisions for complying
with such requirements (such as the Mercury and Air Toxics Standards
(MATS)).\6\ The
[[Page 51063]]
EPA solicited comments on the feasibility of the implementation of the
proposed timeline. See 79 FR 27456, May 13, 2014. The notice of
proposed rulemaking also included a discussion of when the EPA
envisioned the information could potentially be used in designation
actions.
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\6\ In 2012 the EPA promulgated the Mercury and Air Toxics
Standards under Section 112 of the CAA, 42 U.S.C. 7412, that set
emission limits for several hazardous air pollutants. See 77 FR 9304
(Feb. 16, 2012). Installing the technology necessary to reduce
emissions directly regulated by the MATS rule has already reduced
the emissions of SO2. Id. at 9305. On April 15, 2014, the
D.C. Circuit denied 26 consolidated petitions for review of the MATS
rule brought by state, industry, and environmental petitioners in
White Stallion Energy Ctr. v. EPA, No. 12-1100 (and consolidated
cases) (D.C. Cir.). The Supreme Court has reversed and remanded the
D.C. Circuit's decision for further proceedings. Michigan v. EPA,
Nos. 14-46, 14-47, 14-49, 2015 WL 2473453 (June 29, 2015). However,
the MATS rule remains in effect at this time.
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b. Brief Summary of Comments
Several state and industry commenters agreed that the EPA's
proposed timeline was reasonable for acquiring data by either modeling
or monitoring, and for evaluating the submitted data. Many also agreed
that it would be a reasonable schedule for supporting the issuance of
designations and submittal of any SIPs, provided future schedules for
those actions accommodate the schedule for implementing the rule.
However, a larger number of state and industry commenters asserted that
the time allotted for installation of monitors was not sufficient. One
state commenter stated that the feasibility of the schedule will depend
upon the threshold option selected by the EPA. Another state commenter
supported the timeline that the EPA proposed as long as the EPA
finalizes the rule by late 2014 and added that, if promulgation is
delayed, the timeline should be adjusted by as many weeks or months as
the delay in finalizing the rule. Some state and industry commenters
recommended an extension of at least 1 year on all the proposed actions
listed in the implementation timeline. Other commenters felt that the
proposed timeline was flawed for multiple reasons and is, therefore,
not achievable.
c. EPA Response
The EPA recognizes the logistical and financial challenges that
were identified by commenters with respect to the timeline. In
response, the final rule contains changes to provide additional time
for air agencies to determine whether to use modeling or monitoring to
characterize air quality near their affected sources, discussed later
in this section. However, the final rule retains the proposed deadlines
for commencing monitoring or providing modeling. The Agency
acknowledges that these deadlines do not provide as much time as some
commenters would prefer; however, the EPA believes that these deadlines
can be achieved with the appropriate planning, coordination, and
program implementation by air agencies. The EPA notes that if air
agencies conclude that the timeline and resource burdens associated
with installing and conducting improved monitoring are not feasible for
particular areas, they may instead choose the modeling approach, which
is generally less expensive and can be performed more expeditiously
than monitoring, to characterize air quality. Alternatively, in some
cases the source owner and the air agency may be able to establish by
January 2017 a federally enforceable requirement limiting emissions to
less than 2,000 tpy, with the result that further modeling or
monitoring in that area would not be required under the rule unless air
agencies or EPA Regional Administrators conclude it is otherwise
warranted. Because the purpose of this rule is to obtain improved air
quality information in an efficient manner in order that these data may
be used in future actions (such as area designations, redesignations,
or other actions designed to ensure attainment of the 2010
SO2 NAAQS) to protect the public from the short-term health
effects associated with exposure to SO2 concentrations that
exceed the NAAQS, the EPA believes it would not be appropriate to
further extend the timelines for air quality characterization in the
rule.
The EPA believes that any further delay in air quality
characterization around sources identified as a result of this
rulemaking would delay the implementation of the SO2 NAAQS
and, therefore, would impede public health protection in areas that in
the future show violations of the standard based on the data to be
gathered under the rule. The EPA also believes that any significant
delays in monitors becoming operational past the date of January 1,
2017, will certainly delay the potential for monitoring data to be used
to inform actions that depend upon ambient concentration assessments,
possibly past calendar year 2021. Finally, the EPA notes that under the
terms of the March 2015 consent decree, in order to avoid the EPA being
required to designate an area by December 31, 2017, an air agency will
need to have installed and begun operating the new SO2
monitoring system no later than January 1, 2017.
The Agency believes that it is very important to maintain the
proposed timetable for conducting modeling and installing monitoring
sites because of the need for these new data to be available to support
future determinations concerning the attainment status of areas. The
EPA encourages each air agency to engage in early dialogue with the
appropriate EPA Regional Office and with the identified applicable
facilities in order to meet the requirements of the rule. In
particular, in light of the reality of the sometimes complex process of
identifying potential monitoring locations, securing funding, and
installing an appropriate number of new sites, if an air agency is
considering the monitoring approach for one or more areas, early
coordination should improve the air agency's potential for success in
meeting the timing and requirements of the rule.
The final rule retains the January 15, 2016, date for submittal of
a list of sources, because the EPA expects that this information is
relatively straightforward to obtain, and it is beneficial for planning
purposes to have this list available as soon as possible. However, as
mentioned previously, in light of comments, the EPA is promulgating a
schedule that provides an additional six months for the air agency to
specify how it plans to address the area around each listed source. The
EPA is promulgating a schedule in which July 1, 2016, is the deadline
for selecting among the monitoring approach, the modeling approach, or
establishing source emission requirements. If the air agency selects
the monitoring approach for a source area, it must also include in the
annual monitoring plan (also due by July 1, 2016) information about any
new monitoring sites it will establish by January 1, 2017. If the air
agency selects the modeling approach for a source area, it must also
submit a modeling protocol at that time. If the air agency chooses the
option of establishing an enforceable source limit or limits as an
alternative to air quality characterization, it must also at that time
provide a description of the planned emission limitation, including
such information as emission rate, averaging time, and expected legal
mechanism for making the limitation federally enforceable. To suffice
as an alternative to the characterization requirement, the emission
requirements or limits would need to be adopted by the air agency, made
federally enforceable, and require compliance by January 13. 2017.
Further discussion of the rationale for these revisions to the
timetable is provided in the relevant subsections that follow. Table 1
shows
[[Page 51064]]
the final rule timetable, including this revision.
Table 1--Timeline for DRR Implementation
------------------------------------------------------------------------
Date Action
------------------------------------------------------------------------
From promulgation of this rule to Air agency and the EPA Regional
January 15, 2016. Office consult on list of SO2
sources; air agency submits its
list of sources to EPA by January
15, 2016.
July 1, 2016...................... Air agency specifies for each source
whether it will characterize air
quality with modeling, characterize
air quality with monitoring, or
establish a federally enforceable
requirement limiting annual
emissions of the source to less
than 2,000 tpy. For source areas to
be modeled, the air agency submits
a modeling protocol. For source
areas to be monitored, the air
agency submits information about
any new monitoring sites it will
establish by January 1, 2017. For
areas where enforceable emission
limits will be established as an
alternative to air quality
characterization, the air agency
submits a description of the
planned emission limit.
January 1, 2017................... Air agency ensures that SO2 monitors
to satisfy the Data Requirements
Rule are installed and operational.
January 13, 2017.................. For any source identified for
modeling pursuant to the July 1,
2016, milestone, air agency submits
modeling analyses. For any source
identified for emission limit
approach, air agency submits
documentation showing that limits
requiring annual emissions to be
less than 2,000 tpy are effective
and federally enforceable.
May 2020.......................... For any source area identified for
monitoring approach, air agency
certifies 2019 monitoring data,
enabling official design values for
the 2017-2019 time period to be
calculated.
------------------------------------------------------------------------
In addition, while the proposed rule discussed how the timing of
the implementation of this rule would fit with the anticipated schedule
for completing area designations, the proposed rule did not itself
purport to establish a binding schedule for completing designations.
Table 2 provides information concerning the schedule for taking action
to designate areas in the future in accordance with the March 2015
consent decree, but is intended for informational purposes only. In
this rulemaking, we are not addressing comments received on the
proposed rule concerning the designation process because those issues
would be beyond the intended scope of this rulemaking.
Table 2--Anticipated Schedule for Future Rounds of SO2 Designations
------------------------------------------------------------------------
------------------------------------------------------------------------
July 2016......................... Date by which the EPA must issue
final designations for sources
meeting specific criteria in the
March 2015 consent decree.
August 2017....................... Expected date by which the EPA would
notify states of intended
designations based on air quality
data obtained pursuant to the first
round of the data requirements
rule.
December 2017..................... Date by which the EPA must issue
final designations for a majority
of the country (pursuant to March
2015 consent decree), except for
areas with new monitoring networks
commencing operation by January 1,
2017.
August 2019....................... Anticipated due date for state
attainment plans for areas
designated nonattainment in 2017.
May 2020.......................... Certification of 2019 monitoring
data is required by this date.
August 2020....................... Expected date by which the EPA would
notify states of intended
designations for the remainder of
the country.
December 2020..................... Date by which the EPA must issue
final designations for the
remainder of the country (pursuant
to March 2015 consent decree).
August 2022....................... Anticipated due date for state
attainment plans for areas
designated nonattainment in 2020.
------------------------------------------------------------------------
2. Issues Related to Submittal of List of SO2 Sources Where
Air Quality Is To Be Characterized, and Election of Modeling or
Monitoring
a. Submittal of List of Sources Where Air Quality Is To Be
Characterized
i Summary of Proposal
In Sec. 51.1203(a), the EPA proposed to require each air agency to
submit to its respective EPA Regional Administrator by January 15,
2016, a list identifying the specific sources in the state around which
SO2 air quality is to be characterized. The EPA stated 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 Sec. 51.1203 of the
proposed rule, are appropriate steps necessary to characterize
SO2 air quality throughout the country, and are consistent
with sections 110(a)(2)(B), 110(a)(2)(K) and 301(a)(1) of the CAA. In
the docket, the EPA provided a preliminary list of sources that
appeared to meet the EPA's proposed thresholds (based on 2011 emissions
data), and the EPA solicited comments on this list. See 79 FR 27446,
27461, May 13, 2014.
ii. Brief Summary of Comments
Some state and industry commenters opposed the requirement that, by
January 15, 2016, air agencies must submit a list of sources. Some
commenters also stated that submitting a list of sources is unnecessary
for various reasons such as data are already made publicly available on
an annual basis through the national emissions inventory; that it does
not make sense to establish a list that is expected to change; and that
air agencies and the EPA can work cooperatively without a binding
requirement. Commenters also recommended that any listing of sources,
and any identification of the selected air quality characterization
approach for specific source areas, should wait until the January 2017
analysis for individual sources or areas is to be completed. One state
commenter
[[Page 51065]]
indicated that they did not find merit in the citations that the EPA
provided in the proposal regarding the authority for requiring this
list submittal. This commenter stated that the CAA section 110(a)(2)
citations address the requirements for SIP submittals by states for
implementation, maintenance and enforcement of the standard. Several
state commenters also suggested updates or revisions to the EPA's
preliminary list of sources potentially subject to this rule.
iii. EPA Response
The EPA does not agree with commenters who claim that submittal of
an initial list of sources near which air quality is to be
characterized is not needed in January 2016. The EPA believes that it
is important to receive the list of source areas to be characterized
under the rule by January 15, 2016, because it will provide timely
clarity for both EPA and the air agency about which sources and
associated areas are to be characterized for air quality under this
rule. In EPA's judgment, such timely clarity is essential to the
success of the characterization efforts that follow the source
identification step. The list will identify the sources in the state
that exceed the 2,000 tpy emissions threshold based on the most
recently available emissions data, as well as any other source or
sources identified by the air agency or the EPA Regional Administrator
as warranting air quality characterization. Development of this initial
list will be important for air agencies as they prepare to generate
timely air quality information that may be used to inform future
designation, redesignation, or other decisions concerning attainment of
the 2010 SO2 NAAQS.
Retaining this deadline will provide the early opportunity for the
air agency and the EPA to discuss and resolve questions about whether
air quality characterization should be required for a particular area
if, for example, emissions are low in some years and high in others, if
an area has a cluster of smaller sources, or if source-specific or
other factors may warrant the need for air quality characterization. As
a further example, there may also be situations for which the state and
the EPA need to reach agreement on what constitutes the most recent
year of emissions data for specific EGU and non-EGU sources. The list
requirement and deadline will ensure resolution of such questions in
time to enable further characterization requirements to be met.
Thus, the EPA is retaining the January 2016 deadline, as proposed,
for submittal of the list of sources in order to initiate an orderly
process to obtain additional information on ambient SO2
concentrations, and ensure these data are available to support actions
taken for the implementation of the 2010 SO2 NAAQS. While
the Agency has previously acknowledged that some of the deadlines in
this rule do not provide as much time as some commenters would prefer,
the EPA believes that the schedule for providing the list of sources is
a relatively straightforward exercise that can be accomplished within
the required time frame.
The EPA strongly encourages each air agency to consult with its
respective EPA Regional Office to identify sources exceeding the
emission threshold in the final rule, and to identify any other areas
near sources that do not exceed the emission threshold but which would
be appropriate for further air quality characterization. It will be
important for air agencies and the EPA to carry out this consultation
process as early as possible and to reach agreement on the list of
sources to characterize under the rule as quickly and efficiently as
possible. It is also important to note that, due to the overlap between
the criteria for inclusion of sources in this final rule and those in
the March 2015 consent decree, all of the sources identified in the
March 2015 consent decree should also be included on the January 2016
list of sources required for characterization under this rule. The
consent decree requires the designation in July 2016 of areas
associated with an initial list of sources meeting specific criteria.
Depending on the specifics of those designation actions, information
developed to support those actions may serve to meet some or all of the
requirements of this data requirements rule. (See section IV.E, Other
Key Issues and Comments, for more discussion of these issues.)
Regarding comments about EPA's authority to require submittal of a
source list, the EPA believes that the requirements of this rule for
air agencies to submit a list of source areas identified for further
air quality characterization, and the other data submittal requirements
found in Sec. 51.1203 of this rule are appropriate steps needed to
better understand SO2 air quality throughout the country,
and that including such requirements is consistent with sections
110(a)(2)(B), 110(a)(2)(K), and 301(a)(1) of the CAA.
Section 110(a)(2)(B) of the CAA 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) of the CAA
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 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.'' Although both of these provisions
direct what air agencies are required to include in SIPs, they clearly
support the authority of the EPA to prescribe requirements that the
information that SIPs are to ensure can be provided is collected in the
first instance.
In addition, CAA 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 that
additional information is collected and provided so that air agencies
and the EPA can ensure attainment and maintenance of the SO2
NAAQS throughout each state. Finally, the EPA notes that CAA section
114(a)(1) also provides broad authority for the EPA, for the purposes
of developing any implementation plan under section 110 or carrying out
any provision of the CAA, to require monitoring and provision of other
information the Agency may reasonably require (such as modeling
information).
The EPA appreciates the comments on the preliminary list of sources
that appeared likely to be subject to this rule as proposed. The EPA
acknowledges that, for various reasons, such a list of sources could
change up until the time that the list is required to be submitted.
Accordingly, such a list is not being promulgated as part of this rule.
The EPA plans on continuing consultations with air agencies regarding
the source areas that the final rule will require to be characterized.
b. Choice Monitoring or Modeling
i. Summary of Proposal
In Sec. 51.1203(b), the EPA proposed to require each air agency to
state whether it will characterize air quality through improved ambient
air quality monitoring or through air quality modeling techniques by
January 15, 2016. The EPA also proposed in Sec. 51.1203(b) that in an
area with multiple subject 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. For
[[Page 51066]]
situations where multiple sources are located in proximity across state
boundaries, the EPA recommended that the relevant air agencies work
together to determine a common analytical approach for assessing air
quality in that area. See 79 FR 27460, May 13, 2014.
ii. Brief Summary of Comments
Several state and industry commenters stated that the EPA should
provide a more reasonable schedule for air agencies to elect the
monitoring option under the proposed rule. Some commenters suggested
that air agencies should have until January 1, 2017, to make this
determination because they could benefit from using initial modeling
results to inform this decision, such flexibility would reduce burdens
on state regulators, and it could lead to more accurate determinations,
while not impacting the EPA's expected attainment dates for such areas
should the areas become designated nonattainment.
iii. EPA Response
In response to these comments, the EPA is providing additional time
for making the election of modeling or monitoring (or, as discussed
later, for making the election of an alternative approach that
enforceably limits an applicable source's emissions). Accordingly, the
deadline for this election will be July 1, 2016. The EPA recognizes
that evaluating the relative merits of modeling and monitoring for any
particular area, including identification of funding sources for any
new monitoring that might be under consideration, warrants more time
than was provided under the proposed rule. Consistent with this
revision, the EPA is also revising the deadline for air agencies using
modeling to submit modeling protocols for the applicable areas. Thus,
under the final rule, by July 1, 2016, the air agency must submit its
selection of whether each area will be characterized through modeling
or monitoring and, depending on that selection, either must submit a
modeling protocol or must include information in the Annual Monitoring
Network Plan that specifies the monitoring to be conducted to address
the requirements of this rule. The EPA believes that this revised
deadline still provides for timely planning for air quality
characterization to occur (through modeling) or begin (through
monitoring) at the beginning of 2017. Conversely, the EPA does not
agree that any later deadline for selecting the means of addressing air
quality characterization requirements would provide the time and
flexibility to address in a timely way any issues that arise after the
selection is made. The result would be that a later deadline for this
selection could jeopardize timely receipt of information characterizing
air quality.
Notwithstanding this revision, the Agency encourages air agencies
to start their investigation of this issue as soon as practicable. The
EPA strongly encourages each air agency to consult with its respective
EPA Regional Office to identify sources exceeding the emission
threshold in the final rule and any other sources that do not exceed
the emission threshold but near which further air quality
characterization would be warranted. Similarly, the EPA strongly
encourages air agencies to hold early discussions regarding the manner
in which modeling or monitoring might be used. As one example, if the
air agency believes that the existing monitoring network suffices to
characterize air quality, early discussions with the EPA would be
essential for assuring that the intended selection of monitoring is
based on appropriate assumptions regarding the network's ability to
characterize air quality near the applicable source(s) without further
network adjustments.
c. Use of Most Recent Publicly Available Data
i. Summary of Proposal
In Sec. 51.1202, the EPA proposed that the air agency should
identify applicable sources of SO2 based on the most recent
publicly available annual SO2 emissions data for such
sources. The EPA specified in proposed Sec. 51.1200, that ``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
requirements to report continuous emissions monitoring data for EGUs
subject to the acid rain program). The EPA stated that, by January 15,
2016, data for 2014 would be available for EGU sources and 2013 data
would be available for non-EGU sources. By considering the most recent
emissions data, the EPA noted that air agencies 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. The EPA included in the docket to the proposed rule a
preliminary list of sources that appeared to meet the criteria
described in the EPA's proposed source threshold approach and requested
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 from that preliminary list. See, 79 FR 27457, May 13, 2014.
ii. Brief Summary of Comments
Several state and industry commenters generally supported the
approach that the basis for the emissions to be compared to the
threshold would be the latest available 1-year of SO2
emissions data. One industry commenter stated that using the most
recent year of data ensures that any recent emissions reductions that
have occurred will be properly taken into consideration.
One public interest group commenter stated that using the most
recent year as a snapshot may fail to capture sources that simply have
a low year, but normally emit at higher levels, and recommended that
the EPA require that facilities only be excluded under the threshold
if, in prior years, the facilities had similar low total emissions
below the limit. A number of states provided information suggesting
specific modifications to the EPA's preliminary list of sources.
One commenter stated that the rule should not take an ``all in'' or
``all out'' approach based on a simple analysis of 1 year's emissions
or even a 3-year average of emissions alone. The commenter stated that
the EPA seems to allow, or consider, the potential addition of non-
threshold-meeting sources but does not appear to recognize that there
may be instances where the air agencies knowledge and judgment warrants
exclusion of threshold triggering sources. They suggested that air
agencies should be able to take into consideration operational changes
during the 3-year period to determine if a different methodology is
appropriate for determining if a source should be a part of the
analysis.
iii. EPA Response
The EPA continues to believe that the most appropriate generally
applicable basis for determining applicability of the air quality
characterization requirements is the most recent available year of
emissions data for a stationary source as reported to the EPA in
accordance with any existing regulatory requirement. As we have
previously explained, SO2 emissions are trending downward,
due to numerous national and regional requirements that have recently
been adopted and are taking effect. The Agency believes it is
reasonable to account for this trend by basing applicability for this
data requirements rule on the most recent available year of emissions.
[[Page 51067]]
By January 15, 2016, the EPA would expect that 2014 data will be
available for all EGU sources, and 2015 data may be available for many
EGUs in accordance with the requirements of the Acid Rain program and
other emission trading programs that require data certification soon
after the end of the year. These sources report hourly emissions data
to the EPA on a quarterly basis. Emissions data for large
SO2 sources also would be available from annual reporting
required for the AERR. Every 3 years (i.e., 2011, 2014, 2017 and so
on), air agencies must submit to EPA emissions data for SO2
sources with the potential to emit more than 100 tpy. In other years,
the AERR requires states to report emissions data for SO2
sources with the potential to emit more than 2,500 tpy. These annual
reports under the AERR are due 12 months after the end of the emissions
year. Thus, the EPA would expect that in January 2016, states would
have emissions data for calendar year 2014 available for non-EGU
sources over 100 tpy potential to emit. Emissions reporting
requirements for the Acid Rain and AERR programs would be expected to
cover the vast majority, if not all, of the sources subject to the
SO2 DRR.
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 rule or not. Although identifying sources based on
the most recent year of emissions is a reasonable basis for
prioritizing limited modeling and monitoring resources for
characterizing current air quality, the EPA recognizes the concern of
some commenters that there may be sources that in the most recent year
have emissions that are lower than normal and are not representative of
normal operations. In these cases, i.e., where recent emissions are
below 2,000 tpy but no controls have been installed and past
representative emission levels are typically above 2,000 tpy, the state
and the EPA should consider using their discretion to require
additional air quality characterization near such sources.
The EPA also recognizes the concern about sources for which the
most recent year's emissions are unrepresentatively high, i.e., that
some sources may have recent year emissions above 2,000 tpy but
normally emit below that level. Given the trends in emissions, the EPA
believes that situation will be relatively rare. Moreover, the
existence of such sources does not negate the general conclusion that
recent emissions data are an appropriate means for targeting limited
modeling and monitoring resources for characterizing current air
quality.
The EPA believes that a rule that prioritizes resources based on
the most recent year's data is more appropriate for a broader range of
circumstances. The EPA notes, however, that after a source is initially
identified, the air quality characterization requirements require air
agencies to provide at least 3 years of monitoring or modeling data.
The availability of such data will provide the opportunity to give
appropriate consideration to representative emissions when using such
data, as appropriate to the specific use.
d. Shutdowns and Limitations on Emissions Levels by January 13, 2017
i. Summary of Proposal
The EPA noted in the proposed rule that 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 to a consent
decree or other legal requirement), or may choose to shut down, prior
to January 2017 (when the air agency should have ambient monitors
operational and air quality modeling completed). The EPA proposed 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 13, 2017, the air agency can provide the EPA with a legal
agreement confirming that the listed source has permanently and
enforceably shut down, then under the proposal the air agency would
have no further obligation regarding air quality characterization for
this source pursuant to this rulemaking. See 79 FR 27458, May 13, 2014.
ii. Brief Summary of Comments
One state commenter recommended that the EPA revise the rule to
exempt from the list those sources that take an enforceable emission
limitation below the 2,000 tpy emissions threshold before January 13,
2017, even if reductions and applicability of the limitation are only
realized within a reasonable time after January 13, 2017. Several
commenters stated that there is no basis to distinguish between
situations in which a source may provide documentation it will shut
down, and cases where an enforceable limit is established, because in
each case the source would no longer meet the criteria for
characterization under the rule. Another commenter stated that sources
should be able to take federally enforceable limits on a tpy basis
prior to the January 13, 2017, date for air agencies to submit their
modeling analysis to avoid characterization under the rule. Another
state commenter stated that requiring sources to implement controls
prior to submittal of future required SIPs would encourage sources to
make emission reductions while allowing sufficient time to implement
these actions.
Some state and industry commenters recommended that sources should
have until the applicable attainment date for a designated
nonattainment area to complete any enforceable actions that achieve
attainment, provided those actions are committed to by January 13,
2017. Commenters stated that there is insufficient time for sources to
take all the actions needed to implement these controls (including
conducting modeling, determining the required reductions and control
strategies, procuring capital funds, obtaining permits and installing
equipment) under the proposed rule. Commenters stated that allowing
sources to implement controls after January 13, 2017, but before future
attainment dates supports the EPA's desired outcome of achieving
emission reductions as quickly as possible; in contrast, under the
EPA's proposal, sources unable to have enforceable limits in place by
the January 13, 2017, deadline have little incentive to take any action
prior to the anticipated designation deadline of 2020.
iii. EPA Response
The EPA is finalizing the proposed approach to allow a state with a
source that is in operation as of January 15, 2016, but that provides
documentation that the source will shut down permanently prior to
January 13, 2017 pursuant to a federally enforceable mechanism (e.g.,
source-specific SIP revision or minor NSR permit revision submitted to
the EPA by January 13, 2017), to avoid being subject to the requirement
to characterize air quality in the vicinity of the source.
As a result of comments received on the proposed rule, the EPA is
clarifying how this exclusion would work relative to the requirement
for development and submittal in January 2016 of the list of sources
near which air quality is to be characterized. The EPA appreciates that
there might be a source whose most recent year of actual emissions
exceeds the threshold for inclusion on the list, but for which the
state has already adopted, or will soon adopt, enforceable requirements
to shut down by January 2017. Such a source may have significant
emissions during the most
[[Page 51068]]
recent available year, or may even still be in operation on January 15,
2016. The EPA has determined that the clearest way to implement the
exclusion from the air quality characterization requirement is to
require that the air agency initially identify such a source on its
list for SO2 air quality characterization because emissions
in the previous year, which serve as the basis for listing under this
rule, exceeded the emissions threshold. However, the final rule now
includes language in Sec. 51.1203(b) allowing the air agency to
indicate by July 1, 2016, that it will provide the EPA with a federally
enforceable requirement confirming that the source will be permanently
and enforceably shut down by January 13, 2017. For a source for which
the air agency provides documentation of a federally enforceable
requirement that the source will shut down, the air agency will have no
further obligation regarding air quality characterization pursuant to
this rulemaking. This approach accomplishes the intent of the proposal
by implementing the approach in a more clear and straightforward
manner.
Commenters on the proposed rule also suggested that, in a similar
manner, an air agency should not be subject to the air quality
characterization obligation for any source that is initially on the
list of sources due in January 15, 2016 (based on most recent actual
emissions), but that becomes subject to a federally enforceable
requirement to limit annual SO2 emissions to below the 2,000
tpy emissions threshold. The EPA finds merit in those comments that
suggest that the rule allow for similar treatment for sources that
become subject to a federally enforceable emission limit as is allowed
for sources that provide documentation that they will shut down. The
EPA has revised the final rule accordingly, and provides further
discussion below. However, EPA does not agree with commenters who
suggest that sources should have until the applicable designation date,
or attainment date for an area that is designated nonattainment, to
implement controls that were committed to prior to January 13, 2017.
Relying on commitments for emission reductions to occur after 2017
would not be consistent with the main focus of this rule, which is to
provide current, updated information on priority SO2 sources
to the EPA beginning in early 2017 that will inform future area
designations (now required in December 2017 and December 2020 per the
March 2015 consent decree).
As indicated above, a source would be listed for air quality
characterization if its most recent emissions were above the 2,000 tpy
threshold. However, the final rule also allows the air agency to meet
the requirements of this rule by submitting a federally enforceable
emissions limitation (e.g., source-specific SIP revision or minor NSR
permit revision) to the EPA by January 13, 2017, that requires the
affected source to reduce allowable emissions at the source to an
annual rate below the 2,000 tpy threshold level by January 13, 2017. By
July 1, 2016, the air agency would be required to identify the sources
on the list for which it would be using such an approach as an
alternative to modeling or monitoring. For such a source identified on
the list, if the affected air agency has adopted and the source has
become subject to federally enforceable control measures lowering
emissions below 2,000 tpy by January 13, 2017, the air agency will
generally not be required to further characterize the impacts from the
source's emissions solely due to its size as of January 15, 2016.
Although air agencies may follow this option as an alternative to
characterizing areas with sources that limit their emissions to below
the 2,000 tpy size threshold, the EPA believes that air agencies and
the EPA must apply judgment as to whether there are still reasons to
characterize these areas due to other factors. As discussed above, some
areas where all sources emit less than 2,000 tpy may nevertheless
warrant air quality characterization, for example because the area has
a cluster of sources with intermediate emission levels or because the
characteristics of a source or the area warrant it. Thus, some areas
with all sources limited to below 2,000 tpy may still warrant air
quality characterization. Therefore, the EPA urges air agencies to
consult early with the EPA regarding areas that are under consideration
for being addressed in this manner, in order to develop a common
understanding as to whether emission limits under consideration would
suffice as an alternative to air quality characterization for the area.
The EPA believes that allowance for this alternative emission limit
approach is not only consistent with the intent of this rule to
prioritize resources to focus on the largest sources of SO2,
but it also has the additional benefit of providing an incentive for
early emission reductions to occur which will improve air quality in
these areas in an expeditious manner. However, we do acknowledge the
distinction between a formerly large source with no future emissions
and a source with reduced but continuing emissions. The Agency does not
believe it would be appropriate to provide that the latter source can
be excluded from evaluation in all cases. It may be that a source with
emissions newly limited to below the applicability threshold--
particularly one with limits established just below the threshold--may
warrant further characterization, just as a source with actual
emissions below the threshold may warrant characterization in some
instances. For example, air quality characterization would continue to
be warranted in areas with other sources over the applicability
threshold, and in areas where no single source has emissions over the
threshold but the combined emissions of multiple sources warrant air
quality characterization. In evaluating such cases, the air agency
should account for all source emissions contributing to ambient
concentrations in the area, including those remaining emissions from
the source that has just reduced its levels to below the applicability
threshold. For this reason, the rule does not automatically exempt
sources with emissions limited to less than 2,000 tpy from air quality
characterization requirements; the rule instead provides that the air
agency or the EPA may judge that the area should continue to be
required to characterize air quality notwithstanding the new emission
limits. Air agencies are thus advised to consult with their EPA
Regional Office before pursuing this alternative to air quality
characterization for a particular source area.
3. Issues Related to Submittal of Modeling Protocols
a. Summary of Proposal
For source areas that an air agency identifies are to be evaluated
through air quality modeling, the EPA proposed in Sec. 51.1203(d) that
an air agency must also provide a modeling protocol to the EPA Regional
Administrator for review by January 15, 2016. In the proposal, the EPA
stated that the EPA Regional Offices would review the submitted
information and consult with the air agency as expeditiously as
practicable, either approving the submitted information in a similar
manner to approval of annual monitoring plan updates, or having further
discussion with the air agency if adjustments to modeling protocols are
warranted. See 79 FR 27458, May 13, 2014.
b. Brief Summary of Comments
Several commenters stated that 1 year is not enough time to
complete modeling demonstrations. These commenters stated that
depending on the scope of the modeling required, it would take 2 to 4
years to complete the
[[Page 51069]]
entire process. The modeling time estimate will increase if refined
modeling is required to site monitors and if the EPA expects the states
to submit modeling protocols and not conduct any refined modeling to
support monitor placement decisions until the EPA approves the
protocols.
Several state and industry commenters objected to the EPA oversight
of the modeling protocols. Commenters were concerned that the EPA could
not review the plans in a timely manner and could cause delays in the
process. One state commenter stated that, if this oversight and
approval is finalized in this rule, they have serious concerns about
whether 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. One state commenter
suggested that the EPA should clarify that air agencies could provide
to the EPA a modeling protocol framework for review and approval, and
that source-specific review of protocols should be left up to the
respective state agency, consistent with past practices in PSD SIP
approved states as well as past practices supporting Best Available
Retrofit Technology (BART).
Some state and industry commenters recommended that the EPA
oversight/approval of model protocols should be eliminated and air
agencies should be able to determine the best approach, using the
normal course of discussion and cooperation with their respective EPA
Regional modeling contacts, and document that approach with the final
submittal to the EPA. One industry commenter stated that it is
arbitrary and capricious to require EPA approval of state monitoring
and modeling plans when the EPA's technical resources are too stretched
to provide this oversight in a timely manner.
c. EPA Response
The EPA recognizes the concerns of the commenters about the time
and resources needed to develop effective modeling protocols. To
clarify, the final rule does not require EPA approval of modeling
protocols before air agencies may begin conducting modeling, but does
direct air agencies to submit to the EPA modeling protocols by July 1,
2016. As with the modeling itself, directing submission of protocols is
within the EPA's authority to prescribe modeling for the purpose of
predicting the effect on ambient air quality of emissions under CAA
section 110(a)(2)(K), and to prescribe such regulations as are
necessary for the EPA to carry out its functions under CAA section
301(a)(1). It is reasonable for the EPA to establish a process that
provides an opportunity for preliminary EPA assistance to air agencies
to ensure that their subsequent modeling is conducted in a manner that
results in information that can reliably inform subsequent EPA actions
determining air quality status under the SO2 NAAQS. As
explained below, the submission of modeling protocols will increase the
likelihood that subsequent air agency modeling is sufficient for this
purpose, and thus will clearly assist the EPA in carrying out its
functions of determining air quality status.
As noted above, the EPA is allowing air agencies approximately six
additional months to determine whether to characterize air quality
through modeling or monitoring in order to accommodate the concerns
about time needed to make this determination, without delaying the date
by which information for characterizing air quality becomes available.
Consistent with this revision, the EPA is delaying the deadline for
states to submit modeling protocols for sources for which they choose
to characterize air quality through modeling, to match the July 1,
2016, deadline for selecting an air quality characterization approach.
The EPA believes that it is important and valuable for the EPA Regional
Offices to work closely with air agencies to ensure that modeling
protocols are adequate to ensure that the modeling for sources
accurately characterizes air quality near sources. Requiring modeling
protocols will help to keep air agencies from getting too far into the
modeling process in a manner that may not be appropriate, which could
occur absent such preliminary consultation with the EPA and, if it
occurred, could result in the air agency needing to re-conduct modeling
after submission to the EPA. The EPA does not intend to formally
approve these protocols, nor does the EPA believe that a one-size-fits-
all timeline, process, or presumption regarding approval or disapproval
of these protocols is warranted. Nevertheless, the EPA believes that
submittal of protocols will facilitate identification, and resolution
of modeling issues, and will thereby help to avoid a later situation in
which the EPA would not be able to rely upon the air agency's modeling
in subsequent actions determining air quality status. Review of
modeling protocols by the EPA will help ensure that the air agency's
modeling will be appropriate for use in making future determinations
regarding areas' attainment status, such as designations or
redesignations. If an air agency's modeling protocol is not submitted
in advance of the subsequent modeling, the chances are greater that the
EPA may not have critical air quality information when it is needed
(for example, when the EPA intends to make area designations).
Therefore, the EPA believes that a requirement for the air agency to
provide modeling protocols for relevant sources to the EPA Regional
Administrator by July 1, 2016 is a reasonable requirement. The modeling
protocol should include information about issues such as emissions
input data, modeling domain, receptor grid, meteorological data and how
to account for background concentrations.
As was the case for the development of the list of sources and
characterization approaches, the Agency acknowledges that the schedule
for state submittal and the EPA review of modeling protocols is
expeditious. The EPA nevertheless believes that the schedule can be
achieved with appropriate planning, coordination, and program
implementation by air agencies, and believes that it is necessary to
establish expeditious timelines to ensure timely availability of the
air quality information. The EPA Regional Office staff will be
available to consult with air agency officials to refine the modeling
protocols for relevant sources. The EPA Regional Offices will review
the submitted information and consult with the air agency expeditiously
to discuss any recommended adjustments to the protocol.
4. Issues Related To Submittal of Annual Monitoring Network Plans That
Include SO2 Monitoring Network Modifications To Satisfy the
DRR
a. Summary of Proposal
In areas where air quality will be characterized through ambient
monitoring to satisfy this rulemaking, the EPA proposed monitoring
requirements in Sec. 51.1203(c), including the requirement that air
agencies 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. In the proposal, the EPA
encouraged air agencies to work with the EPA Regional Offices in the
development of an appropriate network plan which would include the
rationale for why the proposed number of sites and their individual
locations are appropriate. The EPA stated in the proposal that optional
considerations for siting these monitors are discussed
[[Page 51070]]
in the draft Monitoring TAD.\7\ See 79 FR 27458, May 13, 2014.
---------------------------------------------------------------------------
\7\ The SO2 NAAQS Designations Source-Oriented
Monitoring Technical Assistance Document can be found at http://www.epa.gov/airquality/sulfurdioxide/pdfs/SO2MonitoringTAD.pdf.
---------------------------------------------------------------------------
b. Brief Summary of Comments
Several state and industry commenters asserted that it is
unreasonable for the EPA to assume monitoring plans can be submitted by
the proposed July 1, 2016, deadline. Some commenters stated that it may
not be determined that monitoring would be appropriate in certain areas
until after a lengthy round of initial modeling is complete. Other
commenters stated that siting monitors is a lengthy process which
involves, among other steps, working with the sources and the EPA to
determine where monitors should be located, obtaining access to sites,
identifying funding, and procuring and installing equipment.
Furthermore, one commenter stated that, for sources that choose to
operate monitoring equipment, additional time will be needed to (1)
develop documentation between air agencies and sources to ensure that
sites are adequately maintained and that data are reported in a timely
and complete manner, and (2) to put in place a quality assurance
program consistent with the EPA requirements for the entire monitoring
network.
c. EPA Response
The EPA is finalizing the requirement that any plans to conduct
monitoring to satisfy requirements of this rule (by air agencies,
industry, or other parties) shall be reflected in the state's Annual
Monitoring Network Plan due by July 1, 2016. The Agency believes that
monitoring resources can be appropriately put in place by the January
1, 2017, deadline to satisfy this rule, particularly if air agencies
begin planning as soon as possible. The EPA has encouraged air agencies
to begin the monitor planning process early, particularly for the
largest sources. As stated previously, the EPA believes that while the
schedule for meeting the requirements of this rule is expeditious, the
schedule can be achieved with the appropriate planning, coordination,
and program implementation by affected air agencies. The EPA strongly
encourages air agencies to start their investigation of this issue as
soon as practicable. The EPA also encourages each air agency to consult
with its respective EPA Regional Office to identify sources exceeding
the emission threshold in the final rule and any other sources that do
not exceed the emission threshold but which would warrant the
characterization of nearby air quality. In addition, as stated
previously, the EPA believes that it is necessary to establish
expeditious timelines to ensure timely availability of air quality
information. With this in mind, and in light of the many logistical
concerns raised by commenters and recognized by the EPA, the Agency is
encouraging air agencies to engage with their respective EPA Regional
Offices well in advance of the time by which the Annual Monitoring
Network Plan is due. To this end, states should share their draft
SO2 network design plan for SO2 monitoring
intended to satisfy this rule with the EPA and the public in advance of
the complete Annual Monitoring Network Plan.
The reality of the sometimes complex process of identifying a
location, securing funding and installing a new monitoring site,
necessitates such an approach. The Agency believes that early
interaction between air agencies and the EPA Regional Offices and
industry will likely improve the potential for success in installing an
appropriate number of monitors in appropriate locations around
SO2 emitting facilities identified for characterization in
this rulemaking.
5. Issues Related to Deadline for Operation of SO2 Monitors
a. Summary of Proposal
The EPA proposed in Sec. 51.1203(c)(1) that air agencies that have
chosen to characterize air quality through ambient monitoring must have
any relocated and/or new monitors operational by January 1, 2017. In
the preamble, the EPA explained that, under this approach, it is
anticipated that the first 3 calendar years of data would be collected
from 2017 through 2019, allowing the first design value for each
monitor to be calculated by May 2020. This would allow these new
monitoring data to be used to inform air agency and the EPA
determinations of areas' attainment status in actions that occur in
2020, which could include designations and redesignations. See 79 FR
27458, May 13, 2014.
b. Brief Summary of Comments
One industry commenter stated that the proposed rule reflected a
reasonable timeframe for air agencies to collect the data, either
through monitoring or modeling, that are needed to characterize air
quality in areas and determine whether the 1-hour SO2 NAAQS
is being met. One state commenter also asserted that the feasibility of
this time period will be dependent upon the threshold option selected
by the EPA and, thus, the number of affected sources.
However, more than 10 state and industry commenters asserted that
the short time period between the dates when the monitoring plans need
to be submitted and the monitors are required to be operational is
inadequate. One industry commenter stated that it is technically
infeasible to implement the proposed rule by 2017 and, thus, the EPA's
proposal is arbitrary and capricious.
Several state and industry commenters recommended an extension of
at least 1 year for air agencies to begin actual monitoring. One state
commenter suggested that the EPA should allow monitoring to begin
operation between May 1, 2017, and July 1, 2017, which would be
consistent with its suggested approach allowing air agencies to notify
the EPA of selection of the monitoring option up to January 1, 2017.
This commenter recognized that this approach would likely require
delaying the attainment date, if designations are not made until after
3 calendar years of the new monitoring data are obtained and certified.
This commenter also noted that, if the EPA's approval of an
SO2 monitoring plan under this proposal does not occur until
late 2016, air agencies with winter weather concerns would simply not
have sufficient time to set up a monitoring network by January 1, 2017.
Another state commenter noted that other recent rules establishing new
monitoring requirements (such as NAAQS revisions for NO2,
SO2 and PM2.5) have not required such rapid
deployment of monitors, but have each allowed at least 1.5 years from
submittal of the network plan to operation of the monitor.
c. EPA Response
The EPA recognizes that the logistical and financial burdens of
installing an ambient air monitoring station can vary in difficulty and
the resources required. However, as noted earlier with regard to the
overarching timetables effected by this rule, the Agency believes that,
as with other parts of the implementation schedule, while the schedule
for operating monitors is expeditious, it can be achieved with
appropriate planning, coordination, and program implementation by the
air agency which will allow monitoring resources to be in place by the
deadline. The EPA believes that any further delay in air quality
characterization around sources identified as a result of this
rulemaking will delay implementation of the standard and public health
protection in areas where there may be a violation of
[[Page 51071]]
the standard. The Agency believes that it is most prudent to maintain
the proposed timetable for monitoring network installation because of
the need for use of these new data in a relatively timely manner for
use in making attainment status decisions concerning SO2
areas in the country. Therefore, the EPA is finalizing the date by
which monitors being used to satisfy this rulemaking must be
operational to be January 1, 2017.
As noted previously, if a state chooses to monitor to satisfy the
requirements of this rule, planning for the installation of new
monitors must occur early on, soon after this rule is promulgated. With
this in mind, and in light of the many logistical concerns raised by
commenters and recognized by the EPA, the Agency is encouraging air
agencies to engage with their respective EPA Regions well in advance of
the time by which the Annual Monitoring Network Plan and network
operations are due. The EPA is encouraging air agencies to engage with
their respective EPA Regional Offices, and possibly the industrial
sources needing nearby air quality characterization, to plan an
adequate network design as early as possible after this rule is
promulgated. The reality of the sometimes complex process of
identifying a location, securing funding and installing a new
monitoring site, necessitates such an approach. The Agency believes
that early interaction between air agencies and the EPA Regional Office
and industry will likely improve the potential for success in
installing an appropriate number of monitors in appropriate locations
around SO2 emitting facilities identified in this rulemaking
as needing nearby air quality to be characterized. The EPA also notes
that if air agencies conclude that the timeline and resource burdens
associated with installing and conducting improved monitors are not
feasible for particular areas, they may instead choose the less
resource-demanding and more expeditious method of modeling to
characterize SO2 emissions impacts in such areas.
6. Issues Related To Submittal of Modeling Analyses to the EPA
a. Summary of Proposal
The EPA proposed in Sec. 51.1203(d)(3) that air agencies that
choose modeling to characterize ambient air quality be required to
submit modeling analyses to the EPA Regional Office by January 13,
2017. In the proposal, the EPA recommended that these modeling analyses
should be conducted in accordance with the recommendations in the EPA's
Modeling TAD \8\ or as otherwise agreed upon with the EPA Regional
Office on a case-by-case basis. The EPA stated that 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 the air agency should
provide the EPA with supplemental information about the analysis upon
request.
---------------------------------------------------------------------------
\8\ The Draft SO2 NAAQS Designations Modeling
Technical Assistance Document can be found at http://www.epa.gov/airquality/sulfurdioxide/pdfs/SO2ModelingTAD.pdf.
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The proposal also indicated that where areas have not already been
designated under the 2010 SO2 NAAQS, air agencies could
submit updated designation recommendations, if appropriate, as informed
by their modeling analyses. The proposal noted that in developing any
updated designation recommendations, the air agency should follow the
EPA's most recent SO2 designation guidance.\9\ See 79 FR
27458, May 13, 2014.
---------------------------------------------------------------------------
\9\ The EPA issued initial guidance on the SO2 area
designations process on March 24, 2011. See http://www.epa.gov/air/sulfurdioxide/pdfs/20110411SO2designationsguidance.pdf. Note: The
EPA issued updated SO2 designations guidance. See
``Updated Guidance for Area Designations for the 2010 Primary Sulfur
Dioxide National Ambient Air Quality Standard'', March 20, 2015.
Available at: http://www.epa.gov/airquality/sulfurdioxide/pdfs/20150320SO2designations.pdf.
---------------------------------------------------------------------------
b. Brief Summary of Comments
One state commenter disagreed with the requirement that
comprehensive modeling analyses and related supporting information need
to be submitted to the EPA. This commenter asserted that the modeling
analyses will be conducted by the facility owners and reviewed by the
state air agency, and the air agency should be able to forward just a
summary of the analyses to the EPA with sufficient information for the
EPA to evaluate.
c. EPA Response
The EPA is finalizing its proposed approach of requiring that air
agencies choosing modeling to characterize ambient air quality be
required to submit modeling analyses to the EPA Regional Office.
Irrespective of whether the state or a third party conducts the
modeling, it is the state's responsibility under the CAA to submit the
information that this rule requires. The EPA anticipates that any state
submittal of third-party modeling would reflect a review as to whether
it believes that the modeling satisfies applicable requirements.
Moreover, the EPA anticipates that the submittal would provide adequate
information for the EPA to review the adequacy of the analysis as well.
D. Technical Issues Relating to Modeling and Monitoring
1. Technical Assistance Documents (TADs)
This section of the preamble presents a discussion of the
threshold-based air quality characterization approach to implement the
SO2 NAAQS in areas that contain sources with larger
SO2 emissions, in order to address areas where there may be
higher potential for NAAQS violations that adversely affect public
health. This section discusses the different recommended approaches air
agencies may use to provide the necessary air quality information to
the EPA for areas around those identified sources.
a. Summary of Proposal
In the preamble of the proposed rulemaking, the EPA noted that the
Agency has produced draft, non-binding Monitoring and Modeling TADs
that discuss options, suggested approaches and methods on how
monitoring or modeling efforts to characterize air quality around an
identified source might be conducted. The EPA stated that these
documents can be used to assist air agencies in the implementation of
this rulemaking. See 79 FR 27460, May 13, 2014.
b. Brief Summary of Comments
One industry commenter stated that the proposed rule references and
relies upon guidance provided in the Modeling and Monitoring TADs and
in EPA's Guideline on Air Quality Models; therefore, the commenter
asserted that the documents are subject to review and comment for the
proposed rule. One state commenter asserted that it is challenging to
prepare meaningful comments on the proposal since much of it is
contingent upon the use of the TADs.
Some state and industry commenters urged the EPA to be clearer in
the final preamble that the TADs are guidance and, therefore, are not
binding. One state commenter urged the EPA to explicitly state in the
final rule that air agencies retain the ability to use alternative
methods to those outlined in the TADs. One industry commenter stated
that the EPA's reliance on technical guidance documents that have not
been subject to public notice and comment undermines protections
guaranteed by the Administrative
[[Page 51072]]
Procedure Act. One state commenter stated that because the rule
``requires'' the use of ``. . . separate non-binding draft technical
assistance documents . . .'' and creates significant regulatory
uncertainty for air agencies, they oppose the proposal.
c. EPA Response
The EPA reiterates that the TADs provide recommendations but are
not binding or enforceable and create no obligations on any person.
Although the draft TADs are referenced as recommended approaches in the
preamble to the proposal and in this final rulemaking, they are not
required to be adhered to by any air agency required to characterize
air quality around an SO2 source identified in this
rulemaking. The EPA developed the TADs to aid air agencies seeking
advice in the air quality characterization process required by this
rulemaking. The Agency has indicated that the TADs are meant to be used
as possible tools to aid air agencies. This rulemaking does not codify
the TADs, and none of the comments on the proposed rule regarding the
TADs resulted in changes to the rule itself. The TADs are considered to
be living documents that the EPA may update as necessary over time. The
Agency believes that a modeling protocol or monitoring network design
that follows or references the recommended approaches in the TADs is
likely to be adequate, and will better ensure the success and a timely
fulfilment of the requirements of this rulemaking. However, air
agencies remain free under the final rule to suggest alternative
approaches to those suggested in the TADs. Whether an agency chooses to
follow a TAD or suggest an alternative approach does not affect the
fact that for every approach chosen, the air agency will need to submit
their rationale and approach to the EPA for review on a case-by-case
basis.
The EPA disagrees with the commenters who claimed that the
proposal's reference to the TADs violates the rulemaking requirements
of the Administrative Procedure Act. The Agency did not propose, and is
not promulgating language that the TADs are required to be followed,
and is not changing their status as non-binding technical assistance
documents. In response to the request that the TADs be subjected to
notice and comment, in fact the first drafts of the TADs were
circulated for review and comment by stakeholders, and revised versions
of the TADs were developed in response to those comments.
2. Monitoring and Network Design Issues
a. Summary of Proposal
The EPA proposed that air agencies that select the monitoring
approach to characterize air quality in an area would have the option
to identify appropriate existing monitoring sites, relocate monitors as
appropriate or install new monitors, and have them operational by
January 1, 2017, in order to provide data for use in the anticipated
designations process in calendar year 2020. The EPA proposed to require
that any relocated or new monitors be operated either as SLAMS, or in a
manner equivalent to those monitors operated elsewhere in the SLAMS
network; they do not, however, have to be designated as SLAMS monitors.
In the proposal, the EPA stated that the monitors should use Federal
Reference Methods (FRMs) or FEMs and meet the requirements of 40 CFR
part 58, appendices A, C, and E. Further, the EPA stated that the
resulting data should be reported to the Air Quality System (AQS) and
would be subject to the same annual data reporting and certification
requirements listed in 40 CFR 58.15 and 58.16 as required for SLAMS
data. See 79 FR 27461, May 13, 2014.
b. Brief Summary of Comments
Some commenters suggested that the rule should allow a third party,
such as a facility owner, to cover the expenses of siting and operating
new monitors in coordination with the air agency. One public interest
group commenter stated that there are numerous considerations that make
it unlikely that monitors could be sited at ideal modeled locations,
including access to the location, power hookups, local pollutant
effects and safety from vandalism. Several commenters expressed concern
that the lack of clear criteria for designing an SO2 source-
oriented monitoring network puts air agencies in the unreasonable
position of designing a monitoring network without knowing whether it
will be approved by the EPA.
Some commenters stated that guidance is needed on the number of
monitors required. Commenters stated this issue should not be left up
to negotiations with the EPA Regional Office; rather, a procedure
should be outlined that will provide consistency for all regional
offices and air agencies. Some state and industry commenters suggested
that one monitor may be sufficient and recommended the final rule
include a discussion of the adequacy of one monitor in certain
situations. One industry commenter stated that, because large gradients
in design concentrations for SO2 are likely not present to
the extent that the EPA may expect, the use of a single monitor to
demonstrate NAAQS attainment is sufficient in many cases.
c. EPA Response
The EPA believes that there are no limitations as to who might
operate a monitor or monitors being used to satisfy the requirements of
this rulemaking. It can be a state, local or tribal government,
industry, other third parties or a mix thereof. Whatever the case, the
monitor or monitors should be included as a part of the state's
monitoring plan. The critical issue is that the monitor or monitors
must be either a SLAMS monitor or SLAMS-like monitor, where the latter
might be an industrial or other third party-operated monitor. In either
case, the monitor or monitors must be an FRM or an FEM monitor, and
must adhere to requirements in 40 CFR part 58, appendices A, C, and E,
and adhere to data reporting requirements also contained in 40 CFR part
58. This does require states to provide oversight to any non-SLAMS
sites for which they are claiming to satisfy this rulemaking, as the
states have the final responsibility to ensure the quality of submitted
data that satisfies the intent of this rulemaking.
With respect to concerns over a lack of clear criteria for
designing an SO2 source-oriented monitoring network, the
likelihood to appropriately place one or more monitors, and the issue
of what number of monitors might be required around a source, there is
no one-size-fits-all answer to this question. The EPA indicated in the
preamble to the proposal, and in the draft Monitoring TAD, that the
relative location and number of monitors that might be sufficient to
characterize the air quality around a source is a case-by-case
determination. In general, the main objective is to monitor at, or as
near as possible to, the location(s) where ambient SO2
concentration maxima are expected to occur. Site selection for any
monitoring network is subject to logistical hurdles including site
access, identification or installation of appropriate infrastructure,
telecommunications access, and safety, and state, local, and tribal air
agencies are well versed in the variety of logistics that can be
involved in the installation of an ambient air monitoring station.
These issues undoubtedly can play into what any ambient air monitoring
network ultimately looks like. However, as is the case with all
required ambient air monitoring, responsible air agencies are expected
to establish a clear rationale for the number and placement
[[Page 51073]]
of the monitors it is using to satisfy the requirements of the rule. In
this process, there is flexibility for the state to use professional
judgment in determining what is appropriate for their individual
situations, but they are expected to perform due diligence in
attempting to locate monitors in the most ideal locations possible.
Further, the air agency's recommended number of monitors and
preliminary rationale should be discussed with the EPA Regional Offices
well in advance of the development of an Annual Monitoring Network
Plan. As discussed in the Monitoring TAD, the development of a network
design and its rationale can be informed by a number of types of
analyses which can include the use of air quality modeling, exploratory
monitoring, or analysis of existing data. In any scenario, the state
would need to have a technically credible rationale that supports the
monitoring network design approach that has been chosen to satisfy
requirements in this rulemaking.
As stated previously, the TADs provide recommendations for air
agencies, but are not binding or enforceable, and they create no
obligations on any entity. Although the draft TADs are referenced as
providing recommended approaches in the preamble to the proposal and in
this final rulemaking, there is no specific provision in this rule that
requires the air agency to adhere to the TADs. The TADs have been
provided in order to potentially aid air agencies seeking advice in the
air quality characterization process required by this rulemaking.
3. Areas Failing to Having New Monitors Operational by January 1, 2017
a. Summary of Proposal
Where an air agency has chosen the monitoring approach and
submitted a list identifying the sources near which air quality is to
be monitored, the proposed rule addressed the situation where it
becomes evident that sufficient and appropriate monitoring will not be
operational in a timely manner. The EPA proposed that the area around
the source in question would be functionally ``moved'' to the modeling
pathway, where air quality data characterized by the state under this
rule could inform potential future designations that would be intended
to occur by December 2017. The EPA requested comment on this approach,
and 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 which may be outside of its
control, as well as a situation where an air agency does not act in
good faith to deploy monitors on time. See 79 FR 27461, May 13, 2014.
b. Brief Summary of Comments
One public interest group commenter stated that the 2017 modeling
pathway discussed in the proposal offers a swifter, cheaper, and more
accurate way of assessing air quality, and so did not believe that
states that missed deadlines along the monitoring pathway should be
allowed to further delay designations. Other commenters stated that the
fact that modeling is less expensive than monitoring is not a
substitute for what they believe is the superior accuracy of actual
monitored data; and that they believe the lower costs of modeling do
not offset the regulatory costs and other burdens on sources and
communities that could result from nonattainment designations based on
modeling.
One public interest group commenter stated that because the
monitoring approach already could lead to designations occurring a full
decade after the NAAQS was promulgated, it should be regarded as an
absolute edge-of-the-envelope approach, meaning that failure to meet
monitoring deadlines should result in areas being treated under the
modeling pathway as a default. This commenter stated that setting such
a policy in any final rule would properly incentivize actors to
transmit information to the EPA in a timely manner.
A number of state and industry commenters did not agree that a
would-be monitored area should be automatically designated at the same
time as areas for which the modeling option was chosen in the event of
any delay in monitoring. Commenters also stated that the proposed
penalty for unanticipated monitoring site delays is excessive and there
are too many uncertainties which argue against such automatic actions;
especially in cases where the air agency has exercised all due
diligence to ensure that the monitors are operational by the deadline
in the rule.
c. EPA Response
The EPA is clarifying the relationship between this rule and the
schedule for promulgating designations under CAA section 107. This rule
does not establish any deadlines for designations or prescribe the
manner in which future designations would occur. Therefore, it has
never been the role of this rule, even as proposed, to promulgate
schedules for designations of areas based on whether air agencies
timely implement the rule. However, the proposed milestones for
implementation of the rule were devised in consideration of the
Agency's preferred and anticipated schedule for completing area
designations.
While this rule does not promulgate designation schedules, separate
litigation activities have affected the schedule. On March 2, 2015, the
U.S. District Court for the Northern District of California issued an
order directing the EPA to complete designations pursuant to the
schedule discussed earlier in this document. Affected air agencies
considering the monitoring option under this rule should be aware of
this schedule. Under the terms of the consent decree entered by the
court, in order for the EPA to not be required to designate an area by
December 31, 2017, air agencies choosing the monitoring option under
this rule will need to install and begin operating those monitors by
January 1, 2017. This is the date that the rule requires. However,
while the rule does not provide designations schedules, and thus does
not address how designation schedules would be affected by an air
agency missing this deadline, the March 2015 consent decree does. If
the monitor is not operational by January 1, 2017, the EPA will not be
able to use the future monitoring information to be generated by those
monitors in the initial designation for the area, because the court's
order allows those designations to occur as late as 2020 only if the
monitor is timely installed and operated. Where the January 1, 2017,
deadline is not met, the designations must occur by December 31, 2017,
and will have to depend upon other information available at that time.
The EPA's proposal addresses circumstances in which an air agency
chooses to characterize through monitoring but fails to have monitors
become operational on time. The proposal suggests that in these
circumstances, the agency (or, for that matter, the EPA) would be
required to conduct modeling under this rule and be relieved of further
obligations to conduct monitoring, albeit late. The EPA's intent in its
notice of proposed rulemaking was to explain that in these
circumstances, where an air agency chooses to characterize air quality
with new monitors but failed to have the new monitors operational by
the January 1, 2017, deadline, the EPA envisioned designating such
areas in conjunction with areas being characterized by modeling. That
is, the EPA did not envision delaying the designation for such areas to
the envisioned 2020 date when the Agency anticipates promulgating
designations for areas characterizing air quality through a new
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monitoring network. The EPA must now comply with a court-ordered
designation schedule, in which the court expressly requires that areas
that have not begun operation of a new monitoring network by January 1,
2017, must be designated by December 2017.
Nevertheless, the EPA wishes to clarify that an air agency that
chooses monitoring as its means to meet the air quality
characterization requirements, and commits in its July 2016 Annual
Monitoring Network Plan to conduct such monitoring, remains obligated
to fulfill the original requirement to monitor and to provide the
resulting air quality characterization around a given SO2
source, even if operation of new monitors commences after the January
1, 2017, deadline. If a state fails to meet the January 1, 2017,
deadline, the state must still meet the monitoring requirements for the
area pursuant to 40 CFR part 58, or the EPA may disapprove the state's
monitoring plan for the following year, unless, of course, the
monitoring plan is revised accordingly. Although, as discussed
previously, the EPA will not be able to rely upon the future monitoring
data to issue the designation on the court-ordered schedule, the future
monitoring data may be useful for other purposes such as tracking
progress and making later attainment status determinations needed for
redesignations.
4. Monitor Shut Down
a. Summary of Proposal
In the preamble, the EPA proposed that a monitor that has been
deployed under the monitoring option pursuant to this rule, and is
located in an area that is subsequently designated attainment, may be
eligible for shut down provided that the monitor meets certain
criteria. The EPA proposed in Sec. 51.1203(c)(3) that any
SO2 monitor identified in an approved state annual
monitoring network plan to satisfy the rule requirements may be
eligible for shut down 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 (DV) that is no greater
than 50 percent of the 1-hour SO2 NAAQS. The EPA also
proposed that any SO2 monitor eligible for shutting down
would need to be approved by the EPA Regional Administrator before
monitoring operations could cease. As an alternative, the EPA also
proposed an option in which the same criteria noted earlier would need
to be met, except that the monitor would be eligible to cease
operations if it recorded a design value (DV) in the 3-year period that
is no greater than 80 percent of the 1-hour SO2 NAAQS. The
EPA requested comment on the two proposed options for DV criteria for
SO2 monitor shutdown, as well as other potential values
within the 50-80 percent range. The EPA requested that commenters
provide specific technical rationale supporting any approach they
recommend. See 79 FR 27462, May 13, 2014.
b. Brief Summary of Comments
Some state and industry commenters agreed with the proposal that
monitors placed pursuant to the monitoring option and located in areas
that are designated as attainment should be eligible for shut down.
Commenters also stated that providing state agencies with the
flexibility to shut down unneeded monitors allows agencies to allocate
their limited resources more appropriately. One industry commenter
stated that, if the sources are properly controlled and/or limited by
permit, the risk of significant increases in DVs over time is
relatively low absent new sources entering the affected area. Several
state and industry commenters supported the proposal, with one state
commenter indicating that the use of the 50 percent threshold would be
safe to use because the area would require a significant increase in
future SO2 emission to cause an exceedance of the 1-hour
SO2 NAAQS.
Some state commenters recommended that the threshold of 50 percent
be dropped in the final rule since 40 CFR 58.14 already contains
provisions for shutting down a monitor at 80 percent of the NAAQS.
Commenters stated that there does not seem to be a reason to make the
criteria more stringent than the existing criteria in 40 CFR part 58
and, if the EPA wishes to change those criteria, a revision to 40 CFR
58.14(c)(1) should be considered and made available for comment.
Industry commenters stated that the requirement for annual reporting of
changes in SO2 emissions with the possibility that further
monitoring could be required, argues against the more stringent 50
percent option.
Over 25 commenters supported the use of the 80 percent threshold.
Commenters stated that 80 percent of the NAAQS is a strong enough
criterion for shut down of an SO2 monitor and the 80 percent
criterion is consistent with criteria for shutting down most regulatory
monitors. One public interest group commenter stated that new monitors
should not be shut down since (1) short-term monitor readings may not
be consistent with long-term attainment and (2) the SO2
monitor network needs to be rebuilt. In addition, this commenter
recommended that monitors not be removed if the concentrations they are
recording are trending upward, indicative of potential future problems.
c. EPA Response
The EPA is finalizing the rule to allow any SO2 monitor
identified by an air agency in its approved Annual Monitoring Network
Plan as having the purpose of satisfying Sec. 51.1203 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, and is not otherwise
required as part of a SIP, permit, attainment plan or maintenance plan,
to be eligible for shut down if it produces a DV of no greater than 50
percent of the 1-hour SO2 NAAQS in the first or second 3-
year periods of its operation. The EPA has chosen to adopt this
shutdown allowance so that those monitors that record DVs that are well
below the NAAQS after 3 or 4 years of operation would no longer be
required to operate under the unique provisions of this rule, if they
are otherwise not required under other requirements. This potential
ability to shut down monitors would relieve any resource burden under
this rule on air agencies where NAAQS violations have not and likely
will not occur. This particular provision will not require estimates of
future concentrations as do existing shutdown provisions in 40 CFR
58.14.
More specifically, this monitor shutdown provision works by
assessing how two DVs (i.e, one calculated from monitor data collected
in years 1 through 3, and one from years 2 through 4) would compare to
the 50 percent of the NAAQS shutdown criterion. If a monitor produces a
DV from data collected in years 1 through 3 that is no greater than 50
percent of the NAAQS, it is eligible for shutdown if it is not
otherwise required to operate. If the DV is above the 50 percent
threshold, the monitor must continue operation. If that monitor
produces a DV no greater than 50 percent of the NAAQS from data in
years 2 through 4, it is eligible for shutdown if not otherwise
required to operate. If, instead, the DV is again above the 50 percent
threshold, the air agency must continue to operate the monitor. From
that point forward (i.e., for data collection year 2021 and beyond),
the applicable monitor shutdown provisions are those that exist in 40
CFR 58.14, which include
[[Page 51075]]
probabilistic estimations of future concentrations and other
circumstantial situations that might allow for monitor shutdown.
The Agency would like to note language of particular relevance from
40 CFR part 58 regarding eligibility for shutdown based on recorded
data and calculated design values that exists in Sec. 58.14(c)(1).
This particular provision allows monitoring discontinuation with the
Regional Administrator approval for: ``Any PM2.5,
O3, CO, PM10, SO2, Pb, or
NO2 SLAMS monitor which has shown attainment during the
previous 5 years, that has a probability of less than 10 percent of
exceeding 80 percent of the applicable NAAQS during the next 3 years
based on the levels, trends, and variability observed in the past, and
which is not specifically required by an attainment plan or maintenance
plan. In a nonattainment or maintenance area, if the most recent
attainment or maintenance plan adopted by the state, and approved by
the EPA, contains a contingency measure to be triggered by an air
quality concentration and the monitor to be discontinued is the only
SLAMS monitor operating in the nonattainment or maintenance area, the
monitor may not be discontinued.''
In any circumstance regarding monitor shutdown, whether pursuant to
this final rule or 40 CFR part 58, the air agency must receive the EPA
Regional Administrator approval of a request to cease operation of the
monitor as part of its action on the annual monitoring plan under 40
CFR 58.10 prior to the shutdown of any qualifying monitor. Therefore,
under the final rule, there are two sequential routes for possibly
shutting down a monitor. If a monitor shows DVs greater than 50 percent
of the NAAQS after the first two 3-year periods of its operation and
cannot be approved for shut down under the first sequential route, the
monitoring will continue. However, after 5 years of operation it can be
considered for shutdown if it meets the criteria that the EPA's rules
at 40 CFR 58.14(c)(1) apply, with the EPA Regional Administrator's
approval. These monitors might also be subject to shut down eligibility
as set forth in Sec. 58.14(c)(2), (3), (5), and (6).
5. Annual Reporting Following Monitor Shutdown
a. Summary of Proposal
For any area for which the EPA has approved an air agency's request
for an SO2 monitor to cease operations, the EPA proposed
that the air agency be required to assess SO2 emissions
changes annually, beginning in the year after the monitor ceases
operation. (The proposal contained a similar requirement for modeled
areas, discussed later in this section.) For areas around these sources
in which total SO2 emissions increase over the emissions for
the previous year, the EPA proposed that 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 the air
quality around that source should be further re-assessed. The EPA
proposed that 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. In the proposal,
the EPA stated that, if modeling or monitoring information required to
be submitted by the air agency to the EPA pursuant to Sec. 51.1205
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.
The EPA proposed two options for how the air agency would submit
this report and how the EPA would review and act on it. Under the first
option, the EPA proposed 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 1st each year. In the proposal, the EPA
stated that the inclusion of this verification report as an appendix to
the annual monitoring plan would ensure that the report would be
subject to public review and comments that are to be provided for the
monitoring plan pursuant to regulations at 40 CFR 58.10.
Under the second option, the annual report of emissions data for
sources for which the state ceased the operation of nearby monitors
would be submitted to the EPA in the form of a separate, independent
annual submittal from the state to the EPA Regional Administrator due
by the same July 1st 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,
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 EPA
invited comment on any suggested alternatives to these procedural
options. See 79 FR 27462, May 13, 2014.
b. Brief Summary of Comments
Several state and industry commenters stated that the proposed
annual reporting requirement appears to be unduly burdensome. Some
industry commenters opposed the annual reporting requirement, stating
that SO2 emissions from sources are already available to the
EPA and the need for ongoing data requirements has not been
demonstrated. One state commenter suggested that, if the monitors that
were removed were providing data under 50 percent of the standard,
there is no reason to perform such analyses since an increase in
emissions that would result in such a drastic increase in monitored
design values would surely be associated with changes to operations
that would necessitate air permitting, which evaluates projects for
NAAQS compliance.
One group of state commenters stated that the EPA's proposed July
1st submittal date is unrealistic because states will not have the
required quality-assured emissions monitoring data processed by July
1st. Some state and industry commenters recommended a less burdensome
process in which this verification would take place every 3 to 5 years
instead of annually, pointing out that the EPA publishes the NEI data
every 3 years, the EPA reviews the NAAQS every 5 years, and there is a
5-year ambient monitoring assessment plan required by 40 CFR 58.10.
Commenters requested clarification regarding the determination of
an emissions increase. One state commenter stated that it is unclear
whether an emission increase should be based on an increase greater
than the 3 year average of emissions during the initial monitoring
analysis, an increase above the highest single year of emissions during
the initial monitoring analysis, or some other metric. Some commenters
recommended the comparison be based on some compliant level of
emissions from the year(s) where the monitor demonstrated attainment
with the standard, since the ``increase'' or ``decrease'' in emissions
of SO2 may have resulted in total SO2 emissions
levels well below the annual emission rates during the years when
monitoring data showed compliance.
One tribal and several state commenters supported the option of
including the annual emissions analysis with the annual monitoring
plan. One commenter stated that the analysis of emissions is closely
related to network planning, and this procedure would provide a single
document for public
[[Page 51076]]
inspection and EPA review and approval. Another commenter stated that
the annual monitoring plan may not be the best tool or location to
place modeled data, emission reports, ongoing data requirements, and
requests to cease modeling. Other state commenters recommended that the
monitoring plan verification report be considered a separate element
for ease of processing and for public review.
c. EPA Response
The EPA has decided not to finalize the proposed requirement that
any state with an area for which the EPA has approved the air agency's
request for an SO2 monitor to cease operations must still
assess SO2 emissions changes annually, beginning in the year
after the monitor ceases operation. The EPA made this decision based
upon comments on the proposed rule, and in recognition that a cessation
of monitoring will not occur unless a monitor has measured
SO2 concentrations well below the NAAQS for a given time
period and an EPA Regional Administrator has allowed the shut-down. The
Agency is persuaded by commenters that monitor shutdown provisions,
along with generally applicable emissions reporting requirements, are
of sufficient strength that subsequent additional annual observation
and reporting of SO2 source emissions profiles by states
specifically due to this rulemaking is unnecessary. Further, there are
means by which monitoring can be reinitiated in the future if the
unlikely scenario occurs where SO2 emissions rise
significantly in an area, or other data indicate possible NAAQS
violations in an area after a monitor has been shut-down, mainly
through the EPA Regional Administrator authority granted in 40 CFR part
58, appendix D, section 4.4.3.
6. Modeling Issues
a. AERMOD
i. Summary of Proposal
In the proposal, the EPA stated that the Agency anticipates that in
implementing the rule air agencies would likely use AERMOD to conduct
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. The EPA explained in the
proposed rule that, 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 stated in the proposal that
the Agency is confident that AERMOD can provide accurate predictions of
actual SO2 concentrations given representative meteorology
and accurate emissions inputs. See 79 FR 27463, May 13, 2014.
ii. Brief Summary of Comments
One industry commenter stated that, for certain conventional
SO2 emission scenarios, such as tall stacks at coal fired
EGUs, AERMOD can be at least reasonably predictive. One public interest
group commenter stated that AERMOD modeling performs particularly well
in evaluating emission sources with one or a handful of large emission
points. This public interest group commenter cited a declaration of
Roger W. Brode (EPA) filed in the EPA's successful defense of the 2010
SO2 NAAQS in which he stated that AERMOD is capable of
accurately predicting whether the revised primary SO2 NAAQS
is attained and whether individual sources cause or contribute to a
violation of the SO2 NAAQS. This commenter also stated that
AERMOD has been tested and performs very well during conditions of low
wind speeds, citing comments of Camille Sears.
A number of commenters expressed concern with the use of AERMOD.
Some commenters stated that AERMOD was intentionally designed to over-
predict SO2 concentrations. Several commenters referenced
studies that indicate AERMOD over-predicts, including studies by the
Electric Power Research Institute (EPRI), AECOM and some air agencies.
Commenters identified a number of issues that they believe need to be
addressed because they lead to over-predicting SO2
concentrations, including buoyant line sources, building downwash,
conservative assumptions in terms of model input, modeling of multiple
sources, periods of low wind speed, steep terrain and lack of
representative meteorological data. Commenters stated that the
individual aspects of AERMOD and the EPA's guidance that contribute to
over-prediction of the SO2 concentrations in the context of
the 1[hyphen]hour NAAQS are multiplicative.
iii. EPA Response
In this final rule, the EPA is not promulgating a requirement that
air agencies use AERMOD in all cases, but is retaining the existing
flexibility otherwise provided by the EPA's rules for agencies to
support the use of the best model for a particular case. The EPA's
latest recommendations for making this assessment are contained in the
Modeling TAD. In most cases, the EPA believes that AERMOD will likely
be the model of choice by air agencies to address the requirements of
this rule, unless the application involves a different recommended
model, such as the Buoyant Line and Point Source Dispersion Model
(BLP). Models recommended for particular applications are listed in
appendix A of the EPA's Guideline on Air Quality Models.\10\ Section
3.2 of the EPA's Guideline on Air Quality Models outlines the
procedures for use of alternative models for those cases where an
alternative model may be more appropriate than a preferred model. In
addition, the Modeling TAD also discusses past use of alternative
models for particular applications.\11\ The EPA recommends consultation
with the appropriate reviewing authority or EPA Regional Office to
determine if the use of an alternative model is valid for that
application.
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\10\ Revision to the Guideline on Air Quality Models:
Enhancements to the AERMOD Dispersion Modeling System and
Incorporation of Approaches to Address Ozone and Fine Particulate
Matter'' can be found at http://www.epa.gov/ttn/scram/11thmodconf.htm.
\11\ It is the EPA's intention to update the Modeling and
Monitoring TADs as necessary to reflect any change in policy or to
make clarifications that are necessary. Therefore, any comments on
the TADs themselves that have been submitted in response to the
proposed rule will be addressed as a part of any updates made to the
TADs in the future, rather than in this final rule.
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In addition, as stated previously, the TADs are documents that
provide recommendations but are not binding or enforceable and create
no obligations on any person. Although the draft TADs are referenced as
recommended approaches in the preamble to the proposal and in this
rulemaking, they are not required to be adhered to by any state who is
required to characterize air quality around an SO2 source
identified in this rulemaking. The TADs have been provided in order to
potentially aid air agencies seeking advice in the air quality
characterization process required by this rulemaking.
With regards to concerns regarding model conservatism, EPA recently
proposed updates to AERMOD to address concerns regarding buoyant line
sources, building downwash, and low wind speed issues. See 80 FR 45340
July 29, 2015. With regards to comments about model inputs that lead to
over-estimates, as part of its development, AERMOD has been shown to
perform well against observed concentrations when actual emissions have
been used. The modeling of actual emissions for multiple sources is not
anticipated to cause over-predictions. The modeling TAD also discusses
that the number of sources explicitly modeled in an
[[Page 51077]]
application is expected to be low and that in many cases, a number of
sources in a modeling domain can be represented by background
concentrations instead of being explicitly modeled, thus reducing
potential overestimates in modeling.
b. Emissions Data
i. Summary of Proposal
The EPA proposed that modeling analyses be based on either actual
1-hour SO2 emissions from the most recent 3 years or
federally enforceable allowable emissions. The EPA referred readers to
the Modeling TAD for a more detailed discussion of a range of
recommended options for determining actual emissions. While actual
emissions would be the preferred choice to use for emissions inputs,
air agencies 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. Additional information and recommendations on
this approach are discussed in the Modeling TAD. See 79 FR 27446,
27464, May 13, 2014.
ii. Brief Summary of Comments
More than 30 state and industry commenters supported statements in
the EPA's proposal that allow the use of actual emissions as an input
in the air quality modeling in order to most effectively serve as a
surrogate for comprehensive ambient monitoring results. Several
commenters suggested that the use of allowable emissions as an input to
air quality modeling analyses would result in modeled air quality
values that were higher than air quality levels that would be expected
to be observed by a properly sited ambient monitor. Commenters stated
that using actual emissions is even more important when conducting a
cumulative impact analysis (assessing potential impacts from two or
more sources) since the model's tendency to overestimate ambient air
impacts is compounded when numerous sources are all modeled at peak
emissions at all times.
Several state and industry commenters supported the EPA's proposal
to base the modeling analyses on actual emissions over a 3-year period.
One commenter noted that, in situations where multiple sources are
being modeled, the most recent 3 years of actual emissions data may not
be the same for all sources, particularly if there is a mix of EGUs and
non-EGUs. One state commenter suggested that, if justification can be
provided for an alternative dataset, it too may be considered for
modeling. One state commenter recommended the rule clarify that states
must use the most recent 3 years of emissions data that are available
at the time that a modeling protocol for that area is submitted to the
EPA, and that revised modeling should not be required if more recent
emissions data become available.
iii. EPA Response
When using actual emissions, the EPA believes the most recent 3
years of time varying emissions (e.g., emissions that vary hourly,
seasonally, monthly, daily, etc.) should be modeled since the air
quality modeling is being used as a surrogate for monitoring. The
Modeling TAD gives recommendations on inputting hourly emissions into
AERMOD for those sources with hourly continuous emissions monitoring
(CEM) data and also gives recommendations on inputting time varying
emissions (e.g. seasonally, monthly, etc.) when no hourly emissions are
available and only annual emissions and data such as production logs or
fuel usage are available. However, the final rule does not restrict the
ability of air agencies to use more conservative allowable emissions in
conducting their modeling. In the event that a particular source does
not have the most recent 3 years actual of emissions, it may be
possible to use the most recently available emissions or develop the
most recent 3 years of emissions using recommendations in the Modeling
TAD. The reviewing authority should work with the appropriate EPA
Regional Office on the use of such emissions. For an application that
contains a mix of sources whose emissions data are not concurrent with
each other, it is possible to model all of these sources together
following recommendations in the Modeling TAD. Once a modeling protocol
or modeling analyses have been submitted, there is no requirement to
revise the protocol or modeling respectively if more recent emissions
have become available since the submission, and in the best
professional judgment of the reviewing authority, those emission
changes do not warrant a revision to the protocol or modeling analyses.
c. Accounting for Recent Emission Reductions in Modeling Analyses
i. Summary of Proposal
In the proposal, the EPA noted that, in some cases, air quality
modeling conducted in advance of January 2017 may indicate a violation
of the 1-hour SO2 standard and, to address such situations,
the air agency may wish to consult with the source(s) and take action
to adopt enforceable emissions limitations as necessary prior to
January 2017 to potentially avoid a nonattainment designation. The EPA
proposed that, as long as these controls are implemented and
enforceable as of January 2017, it would be appropriate for the new
lower allowable emissions to be used in the modeling analysis in place
of the higher actual emissions. The EPA proposed that, if the air
agency 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, if that designation
has not yet been issued. See 79 FR 27464, May 13, 2014.
ii. Brief Summary of Comments
A number of commenters supported the inclusion of language
providing the option for states to model more recent emission rates
based on enforceable limits implemented in advance of the January 2017
modeling deadline. Commenters stated that this approach is a reasonable
option which would provide industry with an incentive to achieve timely
emission reductions to meet the regulatory requirements while
potentially relieving air agencies from the requirements that a
nonattainment designation entails, if such a designation has not yet
been issued. One industry commenter requested that the method for
reducing emissions not be limited to installing controls.
Some state commenters requested that the EPA develop methodologies
for air agencies to work with sources whose 2015 emissions are above
the threshold to establish permanent and enforceable emission
limitations that show attainment with the SO2 standards
prior to a designation of such sources' areas. One state commenter
stated that there must be a process that allows for the air agencies'
discretion under extenuating circumstances in order to account for
significant changes at a facility that occurred during the most recent
3 years.
iii. EPA Response
After review of the comments, the EPA continues to believe that it
is appropriate for the air agency to consult with the affected
source(s) and take action to adopt enforceable emissions limitations as
necessary prior to January 2017. As long as the emissions limitations
are in place and enforceable by January 2017, the new allowable
emission limit may be input into the model instead of the actual
emissions of the most recent 3 years.
The EPA expects that a number of emissions sources may be
candidates for this optional approach. Many EGUs
[[Page 51078]]
were subject to compliance deadlines for the MATS in April 2015 (or in
some cases are subject to April 2016 deadlines), and the 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. 78 FR 7162, January 31, 2013.
Therefore, the EPA believes that as long as these emissions
reductions are implemented and enforceable by to January 2017, it would
be appropriate for the new lower allowable emissions to be used in a
modeling analysis in place of the higher actual emissions. The air
quality impacts from such a source would be characterized by the new
enforceable allowable limit and could be used as a basis for future
determinations regarding areas' attainment status.
d. Stack Height
i. Summary of Proposal
The EPA described its view in the proposed rule that actual stack
height is appropriate to use in conjunction with actual emissions in a
modeling approach to characterize current air quality. The EPA also
described its view that, if an air agency chooses to use allowable
emissions, then it should use good engineering practice (GEP) stack
height when the actual stack height exceeds the GEP height because the
GEP height is used when calculating the allowable emission rates. The
EPA noted that additional recommendations on the use of actual stack
height can be found in the Modeling TAD. See 79 FR 27464, May 13, 2014.
ii. Brief Summary of Comments
A number of state and industry commenters supported the EPA's views
on the use of actual stack height in conjunction with actual emissions.
However, several state and industry commenters did not agree that GEP
stack height should be used if a state chooses to use allowable
emissions. Commenters stated the EPA should allow sources to model
using actual stack height regardless of whether they are modeling
actual emissions or allowable emissions since the purpose of the rule
is to estimate, as accurately as possible, conditions that would be
measured at a monitor. Commenters also stated that GEP stack height is
not always a factor in establishing the emissions limit, where such
limits are not established under an implementation plan subject to the
restrictions of CAA section 123; for example, in the context of
emission limits that are established based on emission standards under
CAA section 112, such as the MATS rule. One commenter stated that the
concern about giving inappropriate credit for dispersion techniques is
irrelevant in the context of this designation modeling as CAA section
123 applies only to emission limitation controls.
iii. EPA Response
After consideration of comments, the EPA continues to recommend the
use of actual stack heights when using actual emissions and the use of
GEP height when modeling with allowable emissions where such emissions
limits are or would be subject to CAA section 123 and to the EPA's
corresponding regulations implementing GEP requirements. This would
include limits established under any CAA provision that are intended to
be credited in an implementation plan for attaining and maintaining the
NAAQS. The use of GEP for allowable emissions modeling in such
situations is based on the fact that the modeling conducted to
determine the emissions limits was or would be based on GEP stack
heights. Therefore, if actual stack heights (when above GEP) were used
in such situations, the behavior of the modeled sources would not be
consistent with the modeling results used to determine the emissions
limits relied upon to demonstrate attainment of the NAAQS.
e. Meteorological Data
i. Summary of Proposal
For purposes of conducting modeling that simulates what might be
expected to be measured by an ambient monitor, the EPA recommended the
use of 3 years of meteorological data. The EPA stated that, 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 EPA noted that the Modeling TAD has additional
suggestions on these meteorological inputs. See 79 FR 27465, May 13,
2014.
ii. Brief Summary of Comments
Some commenters recommended the use of 1 year of meteorological
data rather than 3 years and provided several reasons: Use of 1 year of
on-site meteorological data would yield a very robust data set; 3 years
does not provide a significant benefit over 1 year; 1 year of
meteorological data is sufficient for PSD purposes; collection of 3
years of data would delay the running of AERMOD; and collection of 3
years of data would be unnecessarily expensive. Commenters stated that,
while relatively few meteorological databases with 3 years of on-site
meteorological data exist, many sources may have previously collected a
full year of data and should be able to use that data without starting
all over again on an expensive 3-year effort. One state commenter asked
the EPA to clarify what is meant by ``the most recent 3 years.''
One state commenter recommended that up to 5 years of
meteorological data be used and stated that, while a single 3-year
period may not provide adequate confidence in the analysis, 5 years
will provide more 3-year combinations that can be compared to the
NAAQS, and more meteorological data improves confidence in the result.
Some commenters requested that the EPA clarify:
That air agencies need not use concurrent meteorological
data, given that some sites simply do not have concurrent
meteorological data.
Given the lack of 3 years of on-site data in many areas,
the EPA should approve the use of prognostic meteorological data.
iii. EPA Response
The EPA's recommendation is to use the most recent 3 years of
representative site-specific data or when site-specific data are not
readily available, or it is not feasible or cost-effective to collect
site-specific data, the most recent 3 years of representative National
Weather Service meteorological data or other representative data. When
the most recent 3 years of representative meteorological data are not
available, the use of older representative meteorological data can be
used. For such cases, the Modeling TAD offers recommendations on
synching the older meteorological data with the more recent emissions,
especially for those sources utilizing hourly emissions. The Modeling
TAD provides an explanation of the need for 3 years of meteorological
data, even if only 1 year of on-site meteorological data are available.
With regards to the type of meteorological data that are available,
i.e. site-specific, NWS data, or prognostic data, the EPA's Modeling
Guideline should be consulted on the latest acceptable forms
[[Page 51079]]
of meteorological data at the time of the modeling analyses.
f. Modeling Protocol, Including Multiple Sources
i. Summary of Proposal
This rulemaking proposed that each state list the sources that are
to be addressed under this rule and the approach to be used to meet
this rule's requirements (air quality characterization through
monitoring, air quality characterization through modeling, or
establishment of a requirement for a timely source shutdown) for each
source. In preparation for conducting modeling, the EPA proposed that
the state would need to develop a modeling protocol for all the sources
the state plans to model. Specifically, in Sec. 51.1203(d), the EPA
proposed that the air agency consult with the appropriate EPA Regional
Office in developing modeling protocols and submit the protocol to the
Regional Administrator for review. In Sec. 51.1203(d)(1), the EPA
proposed that 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. The EPA stated that details on the
suggested protocol elements and the recommended standard format of this
protocol can be found in the Modeling TAD. See 79 FR 27465, May 13,
2014.
ii. Brief Summary of Comments
Some state and industry commenters requested that the EPA provide
more specific guidance on conducting multi-source modeling analyses.
Commenters stated that leaving these topics for negotiation with the
EPA Regional Office will lead to inconsistent application of guidance
among states. Commenters requested guidance on when a source should be
modeled by itself, when a source should be modeled with other sources
in the surrounding area, more detail on the size and location of
sources that should be included in a multi-source analyses, and who
would be responsible for conducting analyses when sources are located
in multi-state areas. One state commenter requested that guidance on
modeling facilities across state lines should be addressed.
iii. EPA Response
The determination of whether to include nearby sources in a
modeling exercise around a source that exceeds the emissions threshold
is case specific, and a standardized methodology cannot be developed to
fit all scenarios. Therefore, the final rule does not promulgate
requirements addressing nearby sources. The EPA has offered technical
recommendations in the Modeling TAD. The identification of nearby
sources for modeling should rely on sound technical reasoning and best
professional judgment. The EPA emphasizes that not all emissions
sources near the source of interest need to be explicitly modeled, as
in some cases the impacts of those sources can be sufficiently
represented by a background monitor as discussed in the Modeling TAD
and section 8.2 of the EPA's Modeling Guideline.
As stated previously, the TADs provide recommendations but are not
binding or enforceable and create no obligations on any person.
Although the draft TADs are referenced as recommended approaches in the
preamble to the proposal and in this rulemaking, they are not required
to be adhered to by any air agency who is required to characterize air
quality around an SO2 source identified in this rulemaking.
The TADs have been provided in order to potentially aid air agencies
seeking advice in the air quality characterization process required by
this rulemaking. The Agency has indicated that the TADs are meant to be
used as possible tools to aid air agencies. The EPA is not codifying
changes to the TADs in this rulemaking in response to any comments
received on the proposed rule. The TADs are living documents which the
EPA may update as necessary.
g. Ongoing Air Agency Data Requirements for Areas That Were Initially
Modeled
i. Summary of Proposal
The EPA proposed that, for areas with modeled air quality data
based on actual emissions that did not exceed the standard, air
agencies would be required to continue to submit information to the EPA
in subsequent years that provide a reasonable assurance that the area
continues to have air quality that does not exceed the standard. The
EPA proposed three options for how air agencies that rely on modeling
of actual emissions would need to conduct additional emissions and/or
modeling analyses. In the proposed rule, the EPA believed that such
additional analyses would only be needed for areas that had been
designated as ``unclassifiable/attainment'' based on actual emissions-
based modeling. The EPA further noted in the proposed rule that modeled
source areas would not be subject to these ongoing data 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.
In Option 1, the EPA proposed that any air agency that will be
subject to an ongoing data requirement for modeled areas would be
required to assess the most recent SO2 emissions data
annually, beginning in the year after the area is designated as
unclassifiable/attainment, and to conduct updated air quality modeling
every 3 years, and in additional years when the air agency or the EPA
determines that such modeling is warranted. Air agencies would be able
to request that the EPA Regional Administrator approve a suspension of
the triennial modeling requirement for an area if their most recent
modeling DV was less than 50 percent of the NAAQS.
In Option 2, the EPA proposed to require the air agency to provide
the EPA with an assessment of SO2 emissions changes for each
source annually, as in Option 1, but to not have a requirement to
conduct updated air quality modeling every 3 years. For sources for
which the air agency determines that emissions have increased, the air
agency would be required to submit to the EPA an assessment of the
cause of the increase, and provide the EPA with an initial
determination of whether air quality modeling would be needed to verify
that the area around the source continues to have air quality levels
that do not exceed the standard. If the air agency or the EPA
determines that additional air quality modeling is necessary, the air
agency would be required to submit the results of that assessment in a
timely fashion--within 12 months.
In Option 3, the EPA proposed to require the state 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 is
commonly performed using a set of default parameters rather than area-
specific parameters, and it generally simulates air quality levels that
are more ``conservative'' than levels that would be estimated using
area-specific parameters. In the proposal, the EPA stated that 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. Under all
[[Page 51080]]
three options, if the modeling performed indicates that air quality
levels in an area exceed the SO2 NAAQS, the EPA may take any
appropriate action, including, but not limited to, requiring adoption
of enforceable emission limits to ensure that future air quality levels
in the area do not exceed the SO2 NAAQS; redesignation of
the area to nonattainment; or issuance of a SIP call requiring action
by the state to bring the area into attainment.
The EPA requested comment on these three options for ongoing data
requirements for air agencies with sources modeled based on actual
emissions, and requested that each commenter provide a clear rationale
for their position. The EPA also invited comments on any alternative
ideas and asked that the commenter provide a detailed rationale and
estimate of any associated costs for any such recommendations. See 79
FR 27465, May 13, 2014.
ii. Brief Summary of Comments
Several state, environmental, and tribal commenters supported
Option 1. These commenters stated that an approach that simply assesses
SO2 emissions changes at large sources would not account for
variations in meteorological conditions, increased SO2
emissions from interactive sources, or improvements to the actual
modeling computer program. One commenter stated that annual modeling
makes far more sense from the perspective of protecting the public
health, and suggested that modeling once every 3 years is an extremely
periodic and slow way of assessing air quality, such that people living
in the impacted area could be unaware for years, and thus unable to
take action to protect themselves or place pressure on their government
to correct the problem.
Several state and industry commenters opposed Option 1 and stated
that modeling assessments should not be conducted on a 3-year or any
other regular basis. Some believed the requirement to model every 3
years would be an inefficient use of resources and arbitrary since it
would not take into account information which might show that
undergoing a revised modeling analysis would be unnecessary. They
claimed that as long as conditions have remained the same or possibly
improved in the intervening timeframe, additional modeling will provide
no additional useful information. Others opposed Option 1 on the
grounds that no other ambient standard requires such a detailed on-
going analysis. Consistent with their concerns about resources,
commenters supported the aspect of Option 1 that would enable the air
agency to terminate certain ongoing data requirements if air quality
modeling indicated a DV equal to or less than 50 percent of the 1-hour
SO2 NAAQS.
A number of state and tribal commenters objected to Option 2. One
tribal commenter stated that the proposed emissions assessments
required in Option 2, which lack a regular air quality modeling
requirement, are not stringent enough. Some state commenters expressed
concern that this option could lead to an indeterminate number of
future analyses required, and that such open-ended requirements have
cost implications that could strain states' already-limited resources.
On the other hand, more than 20 state and industry commenters supported
Option 2 because it balances providing air quality protection with
level of effort from state regulatory authorities. Several commenters
noted that with SO2 emissions declining on a national level,
remodeling would not be expected to be required and a simple analysis
of the change in emissions would be sufficient to determine the need
for additional modeling. A state commenter suggested providing clearer
guidance regarding what level of emissions increase would trigger
further evaluation of sources, rather than having the air agency
provide an assessment for each source with increased emissions. The
commenter suggested (1) if the original modeling level was equal to or
greater than 90 percent of the standard, then new modeling would be
required for the area in the event there is any increase in emissions
in the area; (2) if the original modeling level was between 50 percent
and 75 percent of the standard, then new modeling would be required for
the area if area emissions increased by 15 percent or more; and (3) if
the original modeling level was less than 50 percent of the standard,
then the ongoing modeling requirement should not apply (similar to the
provision in Option 1).
Another state commenter stated that, ideally, under Option 2,
agencies would have a 2.5-year timeframe to complete the entire ongoing
data requirement process: The first year would consist of preparing and
submitting data for the national emissions inventory for the previous
year; 6 months thereafter agencies would submit a report to the EPA
stating whether air quality modeling is needed; and 12 more months
would then be permitted to perform any additional modeling deemed
necessary.
Regarding Option 3, several state and industry commenters disagreed
with having any default modeling requirement, even for screening
modeling, and opposed this option. Several commenters objected to the
required use of a screening model for the following reasons: Most of
the facilities will have multiple emission points and the screening
tools were not designed to evaluate such complex situations; the
mandatory use of screening models will result in an overly cautious,
ineffective approach to verification; and screening modeling is almost
as complex and time consuming as full-scale modeling and thus this
option would not be a good use of state and the EPA resources.
Lastly, some commenters suggested that the air agency should be
able to choose which ongoing data requirement approach it intends to
follow for a particular area. Another commenter suggested an approach
that would be a combination of all three options, where the air agency
would evaluate emissions changes each year, and then conduct screening
modeling or full-scale modeling if the magnitude of emission changes
warrant.
iii. EPA Response
The EPA recognizes the concerns of commenters about the resource
considerations associated with Options 1 and 3, which for areas with
modeling based on actual emissions and designated as attaining would
require full-scale modeling or screening modeling every 3 years, even
if annual emissions in the area were not increasing. We disagree with
those commenters who oppose any requirement for ongoing data assessment
at all; and with those commenters who suggest a requirement for annual
modeling for all areas. The EPA believes that a reasonable requirement
for ongoing evaluation of priority areas identified by this rule is
important to meeting the public health objectives of this NAAQS while
balancing resource constraints of air agencies in a manageable way. The
EPA agrees with commenters that suggest it would be reasonable to check
emissions changes first, and based on that information, then make a
determination about whether to conduct additional modeling. The EPA is
also mindful of the fact that in this rule, modeling is effectively
serving as a surrogate for monitoring, and so the EPA believes it is
reasonable to have similar approaches for terminating the ongoing data
requirements for both areas where air quality was initially
characterized by monitoring, and areas where air quality was initially
characterized by modeling.
[[Page 51081]]
After considering the comments received on the proposed rule, the
EPA is finalizing a combination of elements from Option 1 and Option 2.
As outlined in proposed Option 2, the final approach requires the air
agency to conduct an assessment of emissions changes annually for all
source areas for which the initial air quality modeling was based on
actual emissions and the area was designated as attaining the standard.
The air agency must provide this assessment to the EPA in the form of a
report, to be submitted by July 1 of the following year. This
assessment should reflect the most recent quality-assured emissions
data available for the relevant sources in the area. The report must
also describe the reason for emissions increases in the previous year
at any listed sources, and must include a recommendation indicating for
which sources and areas the emissions increase was substantial enough
to warrant updated air quality modeling that would help determine air
quality levels relative to the standard.
Adapting suggested criteria from a state commenter (with some
modification), the EPA recommends as a general guideline that the air
agency should conduct additional modeling (using the most recent actual
emissions as inputs) for an area if (1) the original modeling level was
equal to or greater than 90 percent of the standard, and there is any
increase in emissions in the area; or (2) if the original modeling
level was between 50 percent and 90 percent of the standard, and
emissions in the area increased by 15 percent or more. However, the EPA
is not promulgating specific criteria for when additional modeling is
required because the EPA believes that the need for additional modeling
is best judged on a case-by-case basis reflecting case-specific
information on emissions changes and prior modeling results. For
example, if the emissions increase was substantial and the previous
modeling had indicated that air quality in the area was just under the
standard, then air quality modeling would be warranted. In other cases
where air quality has been modeled to be well below the standard and
annual emissions increase only slightly in the following year, the air
agency would be able to exercise judgment regarding whether additional
modeling would be needed. The use of case-specific judgment will be
especially important in cases involving multiple sources or multiple
emission units that may have different emissions-air quality
relationships.
The modeling analysis for the area would then be due within 12
months of the air agency recommendation that such modeling is warranted
(i.e. by July 1 of the following year). In this way, if new modeling is
recommended, the whole process ideally would take 18 months from the
end of the ``ongoing data requirement'' year to when new modeling would
be due (not 30 months as suggested by a state commenter).
The EPA finds that the relatively straightforward approach
described in proposed Option 2 requiring the examination of emissions
data annually (rather than conducting updated air quality modeling
every 3 years for every area) is consistent with the frequency with
which ambient monitoring data is evaluated. This approach also provides
some flexibility to the air agency in recommending whether the
magnitude of emissions changes in an area would be large enough to
warrant new modeling. As compared to Options 1 and 3, this approach
also would be expected to involve less overall workload for air
agencies over time.
In addition, as provided in Option 1, the final rule also includes
a provision in Sec. 51.1205(b) enabling the air agency to terminate
the ongoing data requirement for a modeled area if it meets certain
criteria. The provision is analogous to Sec. 51.1205(a), which allows
for the air agency to obtain EPA approval to cease operation of a new
ambient monitor if the most recent DV is low enough to meet certain
criteria (e.g. less than or equal to 50 percent of the level of the
NAAQS, or meeting the criteria of 40 CFR 58.14). Thus, for areas that
were originally modeled based on actual emissions, Sec. 51.1205(b) of
the rule allows termination of the air agency's annual emission
reporting requirement if the air agency submits an air quality modeling
analysis, using updated actual emissions data from the most recent 3
years, that demonstrates that air quality DVs at all receptors in the
analysis are less than or equal to 50 percent of the 1-hour
SO2 NAAQS, and such demonstration is approved by the EPA
Regional Administrator. Likewise, if the initial modeling of a source
area demonstrates that air quality DVs at all receptors in the analysis
are less than or equal to 50 percent of the 1-hour SO2
NAAQS, and such demonstration is approved by the EPA Regional
Administrator, the area would not be subject to ongoing data
requirements as well. The EPA believes that including this type of
provision in the final rule structures the rule in a balanced way for
both modeled and monitored areas in order to meet the objectives of
ensuring that such areas continue to meet the standard and continue to
protect public health, while recognizing the resource constraints of
air agencies.
h. Procedural Approach for Post-Attainment Annual Reporting
i. Summary of Proposal
The EPA proposed two options regarding the procedures by which air
agencies would submit ongoing data reports to the EPA for source areas
characterized through modeling, and by which the EPA would review and
act on them. Under Option 1, the EPA proposed that 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. The inclusion of
this 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 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 review
and comment on the modified plan. The regulations also indicate that if
the air agency has already provided a public comment opportunity in
developing its revised monitoring plan and has made no further changes
to the plan after reviewing the public comments that were received,
then it could submit the public comments along with the revised plan to
the EPA, and the EPA Regional Administrator would not need to provide a
separate opportunity for comment before approving or disapproving the
plan.
Under Option 2, the ongoing report would not be submitted to the
EPA as an appendix to the annual monitoring network plan, but it would
take the form of a separate, independent submittal from the state to
the EPA Regional Administrator. The EPA proposed that this report would
be due by the same July 1st date each year and that 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, 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.
In the proposed rule, the EPA requested comment on the two
procedural options as well as any alternative ideas suggested by
commenters. For any such recommendations, the EPA requested
[[Page 51082]]
that the commenter provide a detailed rationale and estimate of any
associated costs. See 79 FR 27467, May 13, 2014.
ii. Brief Summary of Comments
Some state, tribal and industry commenters recommended that this
information be included as an appendix to the annual monitoring plan,
rather than as a stand-alone document. One commenter stated that, since
both options have a deadline of July 1st each year, a separate document
would only add more time and resource use. Several state commenters
recommended that the assessment be submitted separately from the annual
monitoring plan. These commenters provided the following rationale:
Since these documents are not related, they should be kept separate;
since the annual report refers to modeling, it will cause less
confusion for the general public if it is a separate document from the
annual monitoring plan; and because the annual monitoring plan and the
emissions inventory submittals are performed by separate work units on
different timelines, it would be better to deliver the products
separately rather than delay one or the other to deliver them together.
iii. EPA Response
After considering the comments received related to both of the
proposed options, the EPA believes that the best approach for the final
rule is to allow the affected air agencies the discretion to either
include the required annual data requirements report for modeled areas
either as an appendix to the state's monitoring plan, or as a stand-
alone document. The air agency will have the flexibility under the
final rule to select the approach that best meets the Agency's
workload, schedule, and particular needs. The EPA believes that either
of the procedural approaches will be sufficient to implement the
ongoing data requirements. Regardless of which approach is chosen by
the air agency, the report must be submitted to the respective EPA
Regional Office by July 1st annually and made available for public
review and comment. The first report is due on July 1st of the year
after the effective date of the area's initial designation and
additional reports are due July 1st of each subsequent year.
E. Other Key Issues and Comments
Comments on the proposed rule also raised several other issues not
already addressed in this document. This section identifies and
addresses the key issues raised by those comments.
1. March 2015 Consent Decree
The proposed rule did not contain any regulatory deadlines for the
EPA to complete area designations under the 2010 SO2 NAAQS.
However, at the same time that the EPA was developing the proposed rule
and the final rule, the agency was also engaged in district court
litigation from public interest groups and some states and state
agencies seeking to have the EPA placed on a binding schedule to
complete the designations. The parties in these cases filed complete
briefs in one of these cases, resulting first in the court finding that
the EPA was liable for having failed to meet the statutory deadline to
complete all area designations. Subsequently, the EPA and the other
parties conducted extensive settlement discussions over the remedy,
i.e., the schedule by which the EPA would complete its duties. This
resulted in a settlement between the EPA and the public interest group
plaintiffs, which the plaintiff-interveners did not join.
On June 2, 2014, the EPA published notice of a proposed consent
decree reflecting this settlement (Sierra Club et al v. McCarthy, Civil
Action No. 3:13-cv-3953-SI (N.D. Cal.)). 79 FR 31325. This proposed
consent decree included deadlines for the EPA to complete designations
in three phases, the latter two of which were due on the same dates
that the EPA discussed as its intended designations dates in the
preamble to the proposed DRR. The EPA received several comments on the
notice informing the public of the proposed consent decree itself, and
in response to this proposed rule.
The EPA is not promulgating deadlines for its completion of area
designations in this final rule. Therefore, any comments directed to
the merits of the consent decree itself are outside the scope of this
rulemaking, and we will not respond to them here. Instead, as discussed
earlier in this document, on March 2, 2015, the court issued an order
entering the consent decree and establishing its deadlines as binding
on the EPA. As also explained earlier, the 2017 and 2020 deadlines for
the latter two stages of designations established by the consent decree
will allow the EPA and states to use the new data and information that
is timely generated by the implementation of this rule to inform the
designations required to be completed by those dates, but it is not
likely that full implementation of the rule can occur quickly enough to
support the next round of designations required by the court's order to
be completed by July 2, 2016.
2. Recommendations for the EPA To Designate Areas as Unclassifiable
Several commenters recommended that the EPA take prompt action to
designate areas with inadequate data for air quality characterization
as unclassifiable. A number of commenters asserted that the EPA cannot
use the rule to supersede the statutory schedule under which the EPA is
required to make area designations, including statutorily-appropriate
``unclassifiable'' designations. One industry group commented that the
CAA does not authorize the EPA to conduct designations according to the
schedule anticipated by the proposed rule preamble, commenting that the
EPA must instead complete designations in accordance with the schedule
under CAA section 107(d)(1) (designating areas unclassifiable where
appropriate), and then redesignating unclassifiable areas as either
attainment or nonattainment later. Similarly, a state commenter
expressed the view that further data are not necessary to meet the CAA.
Several commenters also stated that the proposed rule effectively
nullifies the ``unclassifiable'' designation, use of which would have
allowed the EPA to meet its statutory deadline. One commenter also
stated that the EPA should continue to use the ``unclassifiable''
designation where appropriate, and should not seek to designate all
areas as attainment or nonattainment.
Several commenters also addressed the interrelationship between the
proposed rule and the proposed consent decree for settling the lawsuit
regarding the EPA's failure to promulgate designations for areas
without monitored violations. One state commenter urged that the EPA
codify the proposed consent decree into the rule. Another state
commenter objected to this suggestion, stating that the proposed
consent decree specifies a designations schedule that conflicts with
the proposed schedule and compromises a commenter's ability to comment
on the impact of that consent decree on the rule. An industrial
commenter found the consent decree to undermine the proposed rule.
These commenters urged that the EPA re-propose the relationship between
the consent decree and the rule. An industry group stated that the
issuance of the proposed consent decree undermines the rule because it
would require an early round of designations that would be based on
modeling, in contravention of the process under the proposed rule that
offers the option of basing designations on monitoring data.
[[Page 51083]]
As stated previously, the EPA is not establishing or modifying any
area designation requirements provided for in section 107 of the CAA
through this rulemaking. The purpose of this rulemaking is to require
states to characterize air quality in priority areas throughout the
country where existing ambient monitors may not be adequately
characterizing peak 1-hour SO2 concentrations. The air
quality data obtained as a result of this rulemaking then may be used
in future designations or redesignations, as appropriate. While the
notice of proposed rulemaking described the EPA's anticipated
designations schedule, for purposes of explaining the timeline by which
the EPA anticipates that the data the EPA was proposing to require will
be used, the timeline for possible future use of these data does not
dictate the schedule or the substantive features of the requirements
for obtaining data for air quality characterization purposes, and the
Agency believes it will be highly valuable to obtain these data even if
that occurs after initial designations occur.
While the notice of proposed rulemaking described the EPA's
expectations that designations for areas not already completed in
August 2013 would be completed either in 2017 or in 2020, the
timetables for obtaining additional data are as prompt as the EPA
considers reasonable whether or not such data can be used to inform the
remaining designations, and thus alternate approaches and timetables
for designations would not result in a different timetable for
implementation of the rule's requirements. In particular, whether
designations proceed according to the approach described in the EPA's
notice of proposed rulemaking, or whether areas are first designated
unclassifiable and subsequently redesignated to attainment or
nonattainment, the same timetable, and substance of requirements for
data to support more properly informed future judgments regarding
areas' attainment status is warranted. Because this rulemaking is not
intended to define the designations process and did not propose
regulatory deadlines for issuing designations, it would be
inappropriate in this final rulemaking to codify any particular
schedule for designations action.
The proposed consent decree referenced by the comments concerns
separate legal proceedings that are addressing the EPA's obligations to
designate areas under CAA section 107. The commenters have not
identified why any potential outcome of those proceedings warrants any
particular revision to the rule, nor have they explained why the
validity of the DRR is contingent on use of any particular designations
approach. While the court's decision establishing timing requirements
for the EPA's designations obligations will of course affect the EPA's
approach to designations, including affecting the extent to which the
EPA will be able to use the data required under the rule at various
times in the designations or redesignations processes, these effects do
not determine the validity of the data collection requirements of the
rule. For these reasons, the EPA believes that the ability of
commenters to address issues relevant to the rule was not compromised
by the proposed consent decree and other actions or statements in the
proceedings regarding the EPA's timetable for designations, and the EPA
finds that re-proposal of the rule is not justified.
3. The Cost of Monitoring or Modeling Under this Rule
Several state and industry commenters stated that, because of
funding limitations at the state level, any monitoring or modeling done
to meet the requirements of the rule would likely need to be done by
the affected sources. Commenters also stated that the rule will present
yet another burden on the regulated community when facilities are
already spending resources on emissions reductions projects that are
required as the result of other EPA air quality rules.
Commenters also stated that even if sources voluntarily set up and
operate their own monitors, state and local agencies will nevertheless
still need to dedicate resources to administer the program, provide
technical assistance, conduct performance audits, ensure data quality
and submit the data to the EPA's AQS database each year. Commenters
also stated that the initial state funding should be provided by the
EPA through CAA section 103 or 105 grant funds in order to establish
the monitoring sites required to meet the requirements of the rule.
The EPA recognizes that there will be costs and resources required
to satisfy the requirements of this rulemaking. As suggested by both
state and industry stakeholders who attended the EPA's May-June 2012
stakeholder meetings, in the absence of increased grant funding it may
be necessary for air agencies to rebalance their existing grant funds
for this purpose, or to consider alternative funding approaches such as
working closely with affected sources to assist in funding either the
modeling or monitoring required to meet the requirements of the rule.
Early planning may be helpful to address these funding needs.
Because the CAA assigns to states much of the responsibility for
developing air quality characterization data, the EPA describes the
requirements of this rule in a consistent manner: Air agencies are the
entities with principal responsibility to establish and operate
monitors, and conduct modeling, and to provide air quality data to the
EPA. However, the EPA recognizes that other parties (such as facility
owners) also may perform significant portions of the work that this
rule requires. The EPA would consider monitoring or modeling conducted
by a third party to be an appropriate means for air agencies to obtain
the data necessary to meet the requirements of this rule, provided that
the state provides oversight to assure that (1) any monitoring is
conducted in a manner that is equivalent to SLAMs and quality-assured
in accordance with applicable requirements, and (2) any modeling
analysis that the state submits, even if it was initially provided to
the state by a third party, is done in a reasonable manner and follows
the recommendations in the Modeling TAD or as otherwise agree upon with
the EPA Regional Office on a case-by-case basis.
4. How the DRR Addresses SO2 Sources in Areas That Are
Already Designated
The intent of this DRR is to direct state and tribal air agencies
to characterize air quality in areas around the largest sources of
SO2 emissions, through the use of either air quality
modeling or ambient monitoring, and to provide such data to the EPA.
The additional information required by this rule will be able to inform
future action by the EPA or the state (e.g., future designation
decisions).
The proposed rule did not specifically address whether the
requirement to characterize a sources' SO2 emission impacts
would apply differently based on whether areas containing sources were
still undesignated, or whether they had already been designated as
nonattainment, attainment, or unclassifiable. However, much of the
discussion in the proposed rule preamble concerned how implementation
of the rule might inform future area designations, thus implying that
the air quality characterization requirement might apply only to areas
that remained undesignated at the time of the rule's implementation.
The EPA believes it is necessary to clarify how the rule applies to
areas that have already been designated in some manner, either during
the initial round of designations in August 2013 or in
[[Page 51084]]
subsequent rounds of designations pursuant to the March 2015 consent
decree.
The first question is whether air agencies are required under this
rule to characterize air quality near sources in areas that were
designated as nonattainment in August 2013. See 78 FR 47191, August 5,
2013. In general, we expect nonattainment plans to provide adequate
characterization of the impacts of sources within those nonattainment
areas. Therefore, we have concluded that an air agency will not be
required under this rule to characterize air quality around
SO2 sources located in a designated nonattainment area.
Specifically, we have clarified the definition of ``applicable source''
in Sec. 51.1200 of the final rule to be ``a stationary source that is
(1) not located in a designated nonattainment area, and (2) has annual
actual SO2 emissions of 2,000 tons or more, or has been
identified by an air agency or by the EPA Regional Administrator as
requiring further air quality characterization.'' Thus, as a general
matter, this rule does not require the state's January 2016 list of
sources triggering the requirements of this rule to include sources
located within areas already designated as nonattainment.
However, it may be possible that in some cases an SO2
source or group of sources within the boundary of an existing
nonattainment area can have significant impacts outside the
nonattainment area, potentially raising concerns that these impacts
might not be adequately evaluated in a nonattainment plan. The EPA
notes that for such cases, the air agency and the EPA Regional
Administrator retain the authority under this rule to require
additional characterization of air quality around specific sources
located in an existing nonattainment area, in the same manner that they
retain the authority, as warranted, to require characterization of air
quality around sources that are below the emissions threshold
identified in this rule.
Related questions also arise for sources in areas that will be
subject to evaluation and designation by July 2016 under the March 2015
consent decree regarding SO2 designations. Because all
sources that meet the March 2015 consent decree criteria for
designation by July 2016 will also exceed the 2,000 ton threshold under
this DRR, these sources will need to be included on the January 2016
list of sources subject to requirements for air quality
characterization under this rule. Subsequent designations do not alter
this list. The list is a permanent list of prioritized sources that
excludes sources in areas designated as nonattainment before January
2016 and is not altered by designations promulgated after January 2016.
In particular, the list of sources would not be altered by promulgation
of nonattainment designations in July 2016. Nevertheless, the EPA
expects that if the area around a ``consent decree'' source is
designated as nonattainment by July 2016, pursuant to the consent
decree, then the information that was adequate to inform this
designation would also satisfy the air agency's obligation under this
rule to submit modeling information in January 2017 characterizing air
quality around that source.
The next question is how this rule applies to sources in areas that
have been designated as ``unclassifiable'' or as ``unclassifiable/
attainment.'' \12\ The EPA did not apply these designations to any
areas in August 2013, but the EPA may apply these designations to some
areas in the designations required to be completed by July 2016. This
rule requires air quality characterization for areas previously
designated as unclassifiable, just as it requires air quality
characterization for undesignated areas. If the EPA has previously
determined through a designation action that sufficient information has
not yet been identified to support an attainment or nonattainment
designation (i.e., the area was initially designated as
unclassifiable), then the additional information required by this rule
will be used to inform possible future actions by the EPA or the state
(e.g., to determine whether the area is attaining or not attaining the
standard, and change designation status).
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\12\ While states have and may continue to submit designations
recommendations identifying areas as ``attainment,'' the EPA expects
to continue its traditional approach, where appropriate, of using a
designation category of ``unclassifiable/attainment'' for areas that
the EPA determines meet the NAAQS. The EPA expects to reserve the
category ``unclassifiable'' for areas where the EPA cannot determine
based on available information whether the area is meeting or not
meeting the NAAQS or where the EPA cannot determine whether the area
contributes to a violation in a nearby area. See SO2
designations guidance issued by Stephen D. Page on March 20, 2015,
available at http://www.epa.gov/airquality/sulfurdioxide/pdfs/20150320SO2designations.pdf.
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With regard to ``unclassifiable/attainment'' areas, no areas were
given this designation in the August 2013 designations. However, it is
possible that some areas may be given this designation in the July 2016
designations based on relevant air quality characterization information
(such as air quality modeling) that has been provided by the air agency
or other parties in the designations process. The applicable sources in
any such areas designated pursuant to the March 2015 consent decree
would have also been included in the list of sources that air agencies
would be required to submit to the EPA in January 2016 according to
this rule. If an area has already been designated by the EPA as
``unclassifiable/attainment'' by July 2016 pursuant to the consent
decree, then the EPA expects that, as was the case for areas as
designated nonattainment, the information that was adequate to inform
an unclassifiable/attainment designation would also satisfy the air
agency's obligation under this rule to submit modeling information in
January 2017 characterizing air quality around that source. As a
result, under this rule, the air agency would not be required to
provide additional air quality characterization information to the EPA
by January 2017.
However, these already-designated ``unclassifiable/attainment''
areas would nevertheless be subject to the ongoing data requirements
included in Sec. 51.1205 of this rule. While modeling for purposes of
informing designations promulgated by July 2016 would also be
considered modeling to address the requirements of this rule, the EPA
is promulgating revised rule language that clarifies that the ongoing
data requirements apply to areas modeled based on actual emissions
whether that modeling was conducted for purposes of informing
designations by July 2016 or conducted only for satisfying the
requirements of this rule. Accordingly, Sec. 51.1205(b) has been
modified to apply to any attainment area designated based on modeling
of actual emissions to characterize air quality.
5. How Air Agencies Should Address Modeling and Monitoring in Multi-
State Areas To Meet the Requirements of the Rule
As with the previous issue, a review of the comments and questions
received from states has made the EPA aware of the need to clarify how
the rule applies to situations where an applicable source that is
located in one state or tribal jurisdiction has an impact on
SO2 concentrations in one or more other jurisdictions. While
the final rule preserves the option of the air agency of the
jurisdiction in which the source is located to choose how to satisfy
the air quality characterization requirements of the rule (i.e.,
through either monitoring or modeling), the EPA urges all air agencies
involved to consult and coordinate in order to make appropriate
decisions concerning whether modeling
[[Page 51085]]
or monitoring would be the most effective method to characterize the
peak 1-hour SO2 concentrations in the ambient air affected
by such sources.
If the jurisdiction in which the source is located prefers to
employ ambient monitoring to characterize air quality, the EPA believes
it would be appropriate to use ambient monitoring only if: (1) The air
agency coordinates with the other jurisdiction in identifying
appropriate ambient monitoring sites; and (2) there is an agreement
established with the other jurisdiction (in which peak 1-hour
SO2 impacts are being experienced), and possibly with the
facility owner, regarding logistical, financial and operational
responsibilities associated with the purchase, installation and
operation of the monitor or monitors that is acceptable to all parties.
However, if one or both jurisdictions do not wish to employ ambient
monitoring, and a monitoring agreement cannot be reached, the EPA
believes that the obligation to characterize air quality rests with the
jurisdiction in which the source is located. Without an adequate multi-
jurisdiction monitoring plan, the air agency would need to use modeling
analyses to characterize air quality in the multi-jurisdiction area.
Consultation among all involved jurisdictions will be important for
planning and conducting technically appropriate modeling. The EPA
expects that early and active coordination among all involved parties
can lead to beneficial agreements for characterizing air quality in
multi-jurisdiction areas, and the EPA will work with air agencies to
help facilitate such agreements.
V. Environmental Justice Considerations
The EPA believes the human health or environmental risk addressed
by this action will not have disproportionately high and adverse human
health or environmental effects on minority, low-income, or indigenous
populations because it does not affect the level of protection provided
to human health or the environment under the SO2 NAAQS. When
promulgated, these regulations will require that air agencies
characterize air quality around certain large emissions sources, or
secure emission limits on sources to reduce annual emissions below
2,000 tpy. It is intended that the actions resulting from this rule
would lead to greater protection for U.S. citizens, including minority,
low-income, or indigenous populations, by reducing exposure to high
ambient concentrations of SO2. In addition, this rule will
help communities by informing residents about ambient air quality
around the largest sources of SO2.
VI. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review
This action is not an economically significant action, but raises
novel policy issues and was submitted to the Office of Management and
Budget (OMB) for review. Any changes made in response to OMB
recommendations have been documented in the docket.
B. Paperwork Reduction Act (PRA)
The information collection activities in this rule have been
submitted for approval to the Office of Management and Budget (OMB)
under the PRA. The Information Collection Request (ICR) document that
the EPA prepared has been assigned EPA ICR number 2495.01. A copy of
the ICR is available in the docket for this rule, and is briefly
summarized here. The information collection requirements are not
enforceable until OMB approves them.
The EPA is requiring air agencies to more extensively characterize
ambient SO2 air quality concentrations, pursuant to sections
110(a)(2)(B), 110(a)(2)(K), 301(a) and 114 of the CAA. For purposes of
analysis of the estimated paperwork burden, the EPA assumed that 43
states and tribes would take actions to characterize air quality
through either air quality modeling or ambient monitoring in 412 areas
around SO2 sources emitting 2,000 tpy of more 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 source areas would be characterized through
ambient monitoring, and the other that assumes that all source areas
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 412 SO2 sources
exceeding the 2,000 tpy 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, which would increase costs
proportionally.) Estimates are provided for a 3-year period and include
a calculation for equipment amortization over 7 years (as is typically
done in monitoring-related ICRs). For the period of 2016, 2017, and
2018 (monitoring related expenditures would begin in 2016), the total
approximate average annual monitoring cost, including a calculation for
equipment amortization, is $8,662,110 (total capital, and labor and
non-labor operation and maintenance) with a total burden of 102,869
hours. The annual labor costs associated with these hours is
$7,080,572. Included in the $8,662,110 total are other annual costs of
non-labor operations and maintenance of $706,827 and equipment and
contract costs of $874,711. 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 related to salary cost and
equipment cost, etc., of a total of 52,717 hours and $776,005.
Potential air quality modeling costs are estimated based on the
assumption that air quality for each of the 412 SO2 sources
exceeding the 2,000 tpy threshold would be characterized through air
quality modeling analyses. Based on market research, stakeholder
feedback and assumptions about the procedures to follow when conducting
modeling for designations purposes,\13\ an estimate of modeling costs
for a single modeling run centered on an identified source would be
approximately $30,000. If air agencies choose to characterize air
quality through modeling analyses around all 412 sources expected to be
identified as exceeding the source threshold, then total national costs
for modeling analyses would be estimated at $12,360,000. If these costs
were incurred over the course of 3 years, then the approximate annual
cost for each year over that period would be $4,120,000.
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\13\ 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
[[Page 51086]]
control number. The OMB control numbers for the EPA's regulations in 40
CFR are listed in 40 CFR part 9. When OMB approves this ICR, the agency
will announce that approval in the Federal Register and publish a
technical amendment to 40 CFR part 9 to display the OMB control number
for the approved information collection activities contained in this
final rule.
C. Regulatory Flexibility Act (RFA)
I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. In
making this determination, the impact of concern is any significant
adverse economic impact on small entities. An agency may certify that a
rule will not have a significant economic impact on a substantial
number of small entities if a rule relieves regulatory burden, has no
net burden or otherwise has a positive economic effect on the small
entities subject to the rule. This final rule will not impose any
requirements directly on small entities. Entities potentially affected
directly by this final rule include state, local and tribal governments
and none of these governments are small entities. Other types of small
entities are also not directly subject to the requirements of this
rule.
D. Unfunded Mandates Reform Act (UMRA)
This action does not contain any unfunded mandate of $100 million
or more as described in UMRA, 2 U.S.C. 1531, and does not significantly
or uniquely affect small governments.
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. The
requirement to characterize air quality to inform the area designation
process for the revised NAAQS is imposed by the CAA. This rule is
intended to interpret those requirements as they apply to the 2010 1
hour SO2 NAAQS.
F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments
This action does not have tribal implications, as specified in
Executive Order 13175. It would not have a substantial direct effect on
one or more Indian tribes. Furthermore, this regulation does 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 this regulation does nothing to modify that relationship. Thus,
Executive Order 13175 does not apply to this action.
Consistent with the EPA Policy on Consultation and Coordination
with Indian tribes, 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 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 rule.
The EPA also provided information on the proposed rule and conducted
consultation with the National Tribal Air Association in the form of a
briefing on April 24, 2014, and a webinar on May 21, 2014.
G. Executive Order 13045: Protection of Children From Environmental
Health and Safety Risks
The EPA interprets Executive Order 13045 as applying only to those
regulatory actions that concern environmental health or safety risks
that the EPA has reason to believe may disproportionately affect
children, per the definition of ``covered regulatory action'' in
section 2-202 of the Executive Order. This action is not subject to
Executive Order 13045 because it does not directly involve an
environmental health risk or safety risk.
H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
This action is not a ``significant energy action'' because it is
not likely to have a significant adverse effect on the supply,
distribution or use of energy. The EPA is finalizing this
SO2 DRR to require air agencies to more extensively
characterize ambient SO2 air quality concentrations,
pursuant to sections 110(a)(2)(B), 110(a)(2)(K), 301(a) and 114 of the
CAA. The rule does not prescribe specific control strategies by which
the SO2 NAAQS will be met. Such strategies will be developed
by states on a case-by-case basis only if the information generated by
this rule results in an area being designated nonattainment, thereby
triggering the need for the state to develop an attainment plan for the
area. The EPA cannot predict whether the attainment plan prepared by
the state will include regulations on energy suppliers, distributors,
or users. Thus, the EPA concludes that this rule is not likely to have
any adverse energy effects.
I. National Technology Transfer and Advancement Act
This action does not involve technical standards.
J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations
The EPA believes the human health or environmental risk addressed
by this action will not have potential disproportionately high and
adverse human health or environmental effects on any population,
including any minority, low-income or indigenous populations, because
it does not affect the level of protection provided to human health or
the environment. That level of protection is established by the NAAQS
itself. The results of the evaluation of environmental justice
considerations is contained in section V of this preamble titled,
``Environmental Justice Considerations.''
K. Congressional Review Act (CRA)
This action is subject to the CRA, and the EPA will submit a rule
report to each House of the Congress and to the Comptroller General of
the United States. This action is not a ``major rule'' as defined by 5
U.S.C. 804(2).
L. Judicial Review
Under section 307(b)(1) of the CAA, petitions for judicial review
of this final action must be filed in the United States Court of
Appeals for the District of Columbia Circuit by October 20, 2015.
Filing a petition for reconsideration by the Administrator of this
final action does not affect the finality of this action for the
purposes of judicial review nor does it extend the time within which a
petition for judicial review must be filed, and shall not postpone the
effectiveness of this action.
Statutory Authority
The statutory authority for this action is provided by 42 U.S.C.
7401 et seq., and particularly sections 7403, 7407, 7410, 7414 and
7601.
[[Page 51087]]
List of Subjects in 40 CFR Part 51
Environmental protection, Air pollution control, Intergovernmental
relations, Sulfur oxides.
Dated: August 10, 2015.
Gina McCarthy,
Administrator.
For the reasons stated in the preamble, title 40, chapter I, part
51 of the Code of Federal Regulations is 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. Subpart BB is added 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 providing for attainment.
51.1205 Ongoing data requirements.
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 Sec.
51.100 or in the Clean Air Act (CAA). 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.
Such data may have been required to be reported to the EPA in
accordance with an existing regulatory requirement (such as the Air
Emissions Reporting Rule or the Acid Rain Program); however, annual
SO2 emissions data may be obtained or determined through
other reliable means as well.
Applicable source means a stationary source that is:
(1) Not located in a designated nonattainment area, and
(2) Has actual annual SO2 emissions data of 2,000 tons
or more, or has been identified by an air agency or by the EPA Regional
Administrator as requiring further air quality characterization. 2010
SO2 NAAQS means the primary National Ambient Air Quality
Standard for sulfur oxides (sulfur dioxide) as codified at 40 CFR
50.17, as effective August 23, 2010.
Sec. 51.1201 Purpose.
The purpose of this subpart is to require air agencies to develop
and submit air quality data characterizing maximum 1-hour ambient
concentrations of SO2 across the United States through
either ambient air quality monitoring or air quality modeling analysis
at the air agency's election. These monitoring and modeling data may be
used in future determinations by the EPA regarding areas'
SO2 NAAQS attainment status, or for other actions designed
to ensure attainment of the 2010 SO2 NAAQS and provide
protection to 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
have annual actual SO2 emissions of 2,000 tons or more; or
in whose jurisdiction is located one or more sources of SO2
emissions that have been identified by the air agency or by the EPA
Regional Administrator as requiring further air quality
characterization. For the purposes of this subpart, the subject air
agency shall identify applicable sources of SO2 based on the
most recently available annual SO2 emissions data for such
sources.
Sec. 51.1203 Air agency requirements.
(a) The air agency shall submit a list of applicable SO2
sources identified pursuant to Sec. 51.1202 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 source area subject to requirements for air quality
characterization, the air agency shall notify the EPA by July 1, 2016,
whether it has chosen to characterize peak 1-hour SO2
concentrations in such area through ambient air quality monitoring;
characterize peak 1-hour SO2 concentrations in such area
through air quality modeling techniques; or provide federally
enforceable emission limitations by January 13, 2017 that limit
emissions of applicable sources to less than 2,000 tpy, in accordance
with paragraph (e) of this section, or provide documentation that the
applicable source has permanently shut down. Emission limits in
accordance with paragraph (e) of this section may be established in
lieu of conducting monitoring or modeling unless, in the judgment of
the air agency or the EPA Regional Administrator, the area warrants
further air quality characterization even with the establishment of any
new emission limit(s). If the air agency has chosen to establish
requirements to limit emissions for applicable sources in an area, the
notification from the air agency shall describe the requirements and
emission limits the air agency intends to apply. For any area with
multiple applicable sources, the air agency (or air agencies if a
multi-state area) shall use the same technique (monitoring, modeling,
or emissions limitation) for all applicable sources in the area. If
multiple air agencies have applicable sources in an area, the air
agencies must consult with each other to employ a common technique for
the area.
(c) Monitoring. For each area identified in the notification
submitted pursuant to paragraph (b) of this section as an area for
which SO2 concentrations will be characterized through
ambient monitoring, the required monitors shall be sited and operated
either as SLAMS or in a manner equivalent to SLAMS. In either case,
monitors shall meet applicable criteria in 40 CFR part 58, appendices
A, C, and E and their data shall be subject to data certification and
reporting requirements as prescribed in 40 CFR 58.15 and 58.16. These
requirements include quarterly reporting of monitoring data to the Air
Quality System, and the annual certification of data by May 1 of the
following year.
(1) The air agency shall include relevant information about
monitors used to meet the requirements of this paragraph (c) in the air
agency's Annual Monitoring Network Plan required by 40 CFR 58.10 due
July 1, 2016. The air agency shall consult with the appropriate 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 of this subpart.
(2) All existing, new, or relocated ambient monitors intended to
meet the requirements of this paragraph (c) must be operational by
January 1, 2017 and must be operated continually until approved for
shut down by EPA.
(3) Any SO2 monitor identified by an air agency in its
approved Annual Monitoring Network Plan as having the purpose of
meeting the requirements of this paragraph (c) that: Is not located in
[[Page 51088]]
an area designated as nonattainment as the 2010 SO2 NAAQS is
not also being used to satisfy other ambient SO2 minimum
monitoring requirements listed in 40 CFR part 58, appendix D, section
4.4; and is not otherwise required as part of a SIP, permit, attainment
plan or maintenance plan, may be eligible for shut down upon EPA
approval if it produces a design value no greater than 50 percent of
the 2010 SO2 NAAQS from data collected in either its first
or second 3-year period of operation. The air agency must receive EPA
Regional Administrator approval of a request to cease operation of the
monitor as part of the EPA's action on the Annual Monitoring Network
Plan under 40 CFR 58.10 prior to shutting down any qualifying monitor
under this paragraph (c).
(d) Modeling. For each area identified in the notification
submitted pursuant to paragraph (b) of this section as an area for
which SO2 concentrations will be characterized through air
quality modeling, the air agency shall submit by July 1, 2016, a
technical protocol for conducting such modeling to the Regional
Administrator for review. The air agency shall consult with the
appropriate 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 air agency will account for
background SO2 concentrations.
(2) Modeling analyses shall characterize air quality based on
either actual SO2 emissions from the most recent 3 years, or
on any federally enforceable allowable emission limit or limits
established by the air agency or the EPA and that are effective and
require compliance by January 13, 2017.
(3) Except as provided by Sec. 51.1204, the air agency shall
conduct the modeling analysis for any applicable source identified by
the air agency pursuant to paragraph (a) of this section, 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.
(e) Federally enforceable requirement to limit SO2
emissions to under 2,000 tons per year. For each area identified in the
notification submitted pursuant to paragraph (b) of this sectionas an
area for which the air agency will adopt federally enforceable
requirements in lieu of characterizing air quality through monitoring
or modeling, the air agency shall submit documentation to the EPA by
January 13, 2017, showing that such requirements have been adopted, are
in effect, and been made federally enforceable by January 13, 2017,
through an appropriate legal mechanism, and the provisions either:
(1) Require the applicable sources in the area to emit less than
2,000 tons of SO2 per year for calendar year 2017 and
thereafter; or
(2) Document that the applicable sources in the area have
permanently shut down by January 13, 2017.
Sec. 51.1204 Enforceable emission limits providing for attainment.
At any time prior to January 13, 2017, the air agency may submit to
the EPA federally enforceable SO2 emissions limits
(effective no later than January 13, 2017) for one or more applicable
sources that provide for attainment of the 2010 SO2 NAAQS in
the area affected by such emissions. The submittal shall include
associated air quality modeling and other analyses that demonstrate
that all modeling receptors in the area will not violate the 2010
SO2 NAAQS, taking into account the updated allowable
emission limits on applicable sources as well as emissions limits that
may apply to any other sources in the area. The air agency shall not be
subject to the ongoing data requirements of Sec. 51.1205 for such area
if the air quality modeling and other analyses demonstrate that the
area will not violate the 2010 SO2 NAAQS.
Sec. 51.1205 Ongoing data requirements.
(a) Monitored areas. For any area where SO2 monitoring
was conducted to characterize air quality pursuant to Sec. 51.1203,
the air agency shall continue to operate the monitor(s) used to meet
those requirements and shall continue to report ambient data pursuant
to existing ambient monitoring regulations, unless the monitor(s) have
been approved for shut down by the EPA Regional Administrator pursuant
to Sec. 51.1203(c)(3) or pursuant to 40 CFR 58.14.
(b) Modeled areas. For any area where modeling of actual
SO2 emissions serve as the basis for designating such area
as attainment for the 2010 SO2 NAAQS, the air agency shall
submit an annual report to the EPA Regional Administrator by July 1 of
each year, either as a stand-alone document made available for public
inspection, or as an appendix to its Annual Monitoring Network Plan
(also due on July 1 each year under 40 CFR 58.10), that documents the
annual SO2 emissions of each applicable source in each such
area and provides an assessment of the cause of any emissions increase
from the previous year. The first report for each such area is due by
July 1 of the calendar year after the effective date of the area's
initial designation.
(1) The air agency shall include in such report a recommendation
regarding whether additional modeling is needed to characterize air
quality in any area to determine whether the area meets or does not
meet 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 within 12 months.
(2) An air agency will no longer be subject to the requirements of
this paragraph (b) for a particular area if it provides air quality
modeling demonstrating that air quality values at all receptors in the
analysis are no greater than 50 percent of the 1-hour SO2
NAAQS, and such demonstration is approved by the EPA Regional
Administrator.
(c) Any air agency that demonstrates that an area would meet the
2010 SO2 NAAQS with allowable emissions is not required
pursuant to paragraph (b) of this section to submit future annual
reports for the area.
(d) If modeling or monitoring information required to be submitted
by the air agency to the EPA pursuant to this subpart indicates that an
area is not attaining the 2010 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 2010
SO2 NAAQS, designation or redesignation of the area to
nonattainment, or issuance of a SIP Call.
[FR Doc. 2015-20367 Filed 8-20-15; 8:45 am]
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