Document ID: EPA-R01-OAR-2015-0198-0023
Agency: epa
Document Type: Proposed Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: Connecticut; Infrastructure Requirement for the 2010 Sulfur Dioxide National Ambient Air Quality Standard
Posted Date: 2017-05-08T04:00Z

[Federal Register Volume 82, Number 87 (Monday, May 8, 2017)]
[Proposed Rules]
[Pages 21351-21363]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-09183]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R01-OAR-2015-0198; FRL-9961-16-Region 1]

Air Plan Approval; CT; Infrastructure Requirement for the 2010 
Sulfur Dioxide National Ambient Air Quality Standard

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve the remaining portion of a State Implementation Plan (SIP) 
revision submitted by the State of Connecticut. This revision addresses 
the interstate transport requirements of the Clean Air Act (CAA), 
referred to as the good neighbor provision, with respect to the 2010 
sulfur dioxide (SO2) national ambient air quality standard 
(NAAQS). This action proposes to approve Connecticut's demonstration 
that the state is meeting its obligations regarding the transport of 
SO2 emissions into other states. This action is being taken 
under the Clean Air Act.

DATES: Written comments must be received on or before June 7, 2017.

ADDRESSES: Submit your comments, identified by Docket ID Number EPA-
R01-OAR-2015-0198 by one of the following methods:
    1. http://www.regulations.gov: Follow the on-line instructions for 
submitting comments.
    2. Email: dahl.donald@epa.gov.
    3. Fax: (617) 918-0657.
    4. Mail: ``Docket Identification Number EPA-R01-OAR-2015-0198,'' 
Donald Dahl, U.S. Environmental Protection Agency, EPA New England 
Regional Office, Office of Ecosystem Protection, Air Permits, Toxics, 
and Indoor Programs Unit, 5 Post Office Square--Suite 100, (mail code 
OEP05-2), Boston, MA 02109--3912.
    5. Hand Delivery or Courier. At the previously listed EPA Region I 
address. Such deliveries are only accepted during the Regional Office's 
normal hours of operation. The Regional Office's official hours of 
business are Monday through Friday, 8:30 a.m. to 4:30 p.m., excluding 
legal holidays.
    Instructions: Direct your comments to Docket ID No. EPA-R01-OAR-
2015-0198. EPA's policy is that all comments received will be included 
in the public docket without change and may be made available online at 
http://www.regulations.gov, including any personal information 
provided, unless the comment includes information claimed to be 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Do not submit through http://www.regulations.gov, or email, information that you consider to be CBI 
or otherwise protected. The http://www.regulations.gov Web site is an 
``anonymous access'' system, which means EPA will not know your 
identity or contact information unless you provide it in the body of 
your comment. If you send an email comment directly to EPA without 
going through http://www.regulations.gov your email address will be 
automatically captured and included as part of the comment that is 
placed in the public docket and made available on the Internet. If you 
submit an electronic comment, EPA recommends that you include your name 
and other contact information in the body of your comment and with any 
disk or CD-ROM you submit. If EPA cannot read your comment due to 
technical difficulties and cannot contact you for clarification, EPA 
may not be able to consider your comment. Electronic files should avoid 
the use of special characters, any form of encryption, and be free of 
any defects or viruses.
    Docket: All documents in the electronic docket are listed in the 
http://www.regulations.gov index. Although listed in the index, some 
information is not publicly available, i.e., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, is not placed on the Internet and will be 
publicly available only in hard copy form. Publicly available docket 
materials are available at http://www.regulations.gov or at U.S. 
Environmental Protection Agency, EPA New England Regional Office, 
Office of Ecosystem Protection, Air Quality Planning Unit, 5 Post 
Office Square--Suite 100, Boston, MA. EPA requests that if at all 
possible, you contact the contact listed in the FOR FURTHER INFORMATION 
CONTACT section to schedule your inspection. The Regional Office's 
official hours of business are Monday through Friday, 8:30 a.m. to 4:30 
p.m., excluding legal holidays.
    In addition, copies of the state submittal and EPA's technical 
support document are also available for public inspection during normal 
business hours, by appointment at the State Air Agency; the Bureau of 
Air Management, Department of Energy and Environmental Protection, 
State Office Building, 79 Elm Street, Hartford, CT 06106-1630.

FOR FURTHER INFORMATION CONTACT: Donald Dahl, (617) 918-1657; or by 
email at dahl.donald@epa.gov.

SUPPLEMENTARY INFORMATION: Throughout this document whenever ``we,'' 
``us,'' or ``our'' is used, we mean EPA.

Table of Contents

I. Background
II. Summary of the Proposed Action
III. Section 110(A)(2)(D)(i)(I)--Interstate Transport
    A. General Requirements and Historical Approaches for Criteria 
Pollutants
    B. Approach for Addressing the Interstate Transport Requirements 
of the 2010 Primary SO2 NAAQS in Connecticut

[[Page 21352]]

    C. Prong 1 Analysis--Significant Contribution to Nonattainment
    1. SO2 Emissions Trends
    2. SO2 Ambient Air Quality
    3. SO2 Air Dispersion Modeling
    a. Emission Rates and Modeling Domain
    b. Meteorology and Background Air Quality
    i. Interpretation of Modeling Results
    ii. Modeled Results and Impacts on Neighboring States
    4. SIP Approved Regulations Specific to SO2 and 
Permitting Requirements
    5. Other SIP-Approved or Federally Enforceable Regulations
    6. Conclusion
    D. Prong 2 Analysis--Interference With Maintenance of the NAAQS
IV. Proposed Action
V. Statutory and Executive Order Reviews

I. Background

    On June 22, 2010 (75 FR 35520), EPA promulgated a revised primary 
NAAQS for SO2 at a level of 75 ppb, based on a 3-year 
average of the annual 99th percentile of 1-hour daily maximum 
concentrations. Pursuant to section 110(a)(1) of the CAA, states are 
required to submit SIPs meeting the applicable requirements of section 
110(a)(2) within three years after promulgation of a new or revised 
NAAQS or within such shorter period as EPA may prescribe. These SIPs, 
which EPA has historically referred to as ``infrastructure SIPs,'' are 
to provide for the ``implementation, maintenance, and enforcement'' of 
such NAAQS, and the requirements are designed to ensure that the 
structural components of each state's air quality management program 
are adequate to meet the state's responsibility under the CAA. A 
detailed history, interpretation, and rationale of these SIPs and their 
requirements can be found among other citations, in EPA's May 13, 2014 
proposed rule titled, ``Infrastructure SIP requirements for the 2008 
Lead NAAQS'' in the section, ``What is the scope of this rulemaking?'' 
(see 79 FR 27241 at 27242-27245). Section 110(a) of the CAA imposes the 
obligation upon states to make a SIP submission to EPA for a new or 
revised NAAQS, but the contents of individual state submissions may 
vary depending upon the facts and circumstances. The content of the 
revisions proposed in such SIP submissions may also vary depending upon 
what provisions the state's approved SIP already contains.
    On May 30, 2013, the Connecticut Department of Energy and 
Environmental Protection (CT DEEP) submitted a revision to its SIP, 
certifying its SIP meets the requirements of section 110(a)(2) of the 
CAA with respect to the 2010 SO2 NAAQS. On June 3, 2016 (81 
FR 35636), EPA approved CT DEEP's certification that its SIP was 
adequate to meet most of the program elements required by section 
110(a)(2) of the CAA with respect to the 2010 SO2 NAAQS. 
However, at that time, EPA did not take action on CT DEEP's 
certification that its SIP met the requirements of section 
110(a)(2)(D)(i)(I). EPA is now proposing to act on this element, 
section 110(a)(2)(D)(i)(I) of CT DEEP's May 30, 2013 submission to 
address the 2010 SO2 NAAQS.

II. Summary of the Proposed Action

    This proposed approval of Connecticut's SIP addressing interstate 
transport of SO2 is intended to show that the state is 
meeting its obligations regarding CAA section 110(a)(2)(D)(i)(I) 
relative to the 2010 SO2 NAAQS.\1\ Interstate transport 
requirements for all NAAQS pollutants prohibit any source--or other 
type of emissions activity--in one state from emitting any air 
pollutant in amounts that will contribute significantly to 
nonattainment, or interfere with maintenance, of the NAAQS in another 
state. As part of this analysis, and as explained in detail below, EPA 
has taken several approaches to addressing interstate transport in 
other actions based on the characteristics of the pollutant, the 
interstate problem presented by emissions of that pollutant, the 
sources that emit the pollutant, and the information available to 
assess transport of that pollutant.
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    \1\ This proposed approval of Connecticut's SIP under CAA 
section 110(a)(2)(D)(i)(I) is based on the information contained in 
the administrative record for this action, and does not prejudge any 
other future EPA action that may make other determinations regarding 
Connecticut's air quality status. Any such future actions, such as 
area designations under any NAAQS, will be based on their own 
administrative records and EPA's analyses of information that 
becomes available at those times. Future available information may 
include, and is not limited to, monitoring data and modeling 
analyses conducted pursuant to EPA's Data Requirements Rule (80 FR 
51052, August 21, 2015) and information submitted to EPA by states, 
air agencies, and third party stakeholders such as citizen groups 
and industry representatives.
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    Despite being emitted from a similar universe of point and nonpoint 
sources, interstate transport of SO2 is unlike the transport 
of fine particulate matter (PM2.5) or ozone that EPA has 
addressed in other actions in that SO2 is not a regional 
mixing pollutant that commonly contributes to widespread nonattainment 
of the SO2 NAAQS over a large (and often multi-state) area. 
While transport of SO2 is more analogous to the transport of 
lead (Pb) since its physical properties result in localized pollutant 
impacts very near the emissions source, the physical properties and 
release height of SO2 are such that impacts of 
SO2 do not experience the same sharp decrease in ambient 
concentrations as rapidly and as nearby as for Pb. Emissions of 
SO2 travel further and have sufficiently wider ranging 
impacts than emissions of Pb to require a different approach than 
handling Pb transport, but not far enough to be treated in a manner 
similar to regional transport pollutants such as ozone or 
PM2.5.
    Put simply, a different approach is needed for interstate transport 
of SO2: The approaches EPA has adopted for Pb transport are 
too tightly circumscribed to the source, and the approaches for ozone 
or PM2.5 transport are too regionally focused. 
SO2 transport is therefore a unique case, and EPA's 
evaluation of whether Connecticut has met is transport obligations was 
accomplished in several discrete steps. First, EPA evaluated what 
universe of sources are likely to be responsible for SO2 
emissions that could contribute to interstate transport. An assessment 
of the 2014 National Emissions Inventory (NEI) for Connecticut made it 
clear that the vast majority of SO2 emissions in Connecticut 
are from fuel combustion at point and nonpoint sources, and therefore 
it would be reasonable to evaluate the downwind impacts of emissions 
from the combined fuel combustion source categories in order to help 
determine whether the state has met is transport obligations.
    Second, EPA selected a spatial scale--essentially, the geographic 
area and distance around the point sources in which we could reasonably 
expect SO2 impacts to occur--that would be appropriate for 
its analysis, ultimately settling on utilizing an ``urban scale'' with 
dimensions from 4 to 50 kilometers from point sources given the 
usefulness of that range in assessing trends in both area-wide air 
quality and the effectiveness of large-scale pollution control 
strategies at those point sources. As such, EPA utilized an assessment 
up to 50 kilometers from fuel-combustion point sources in order to 
assess trends in area-wide air quality that might have an impact on the 
transport of SO2 from Connecticut to downwind states.
    Third, EPA assessed all available data at the time of this 
rulemaking regarding SO2 emissions in Connecticut and their 
possible impacts in downwind states, including: SO2 ambient 
air quality; SO2 emissions and SO2 emissions 
trends; SIP-approved SO2 regulations and permitting 
requirements; available air dispersion modeling; and, other SIP-
approved or Federally promulgated regulations which may yield 
reductions of SO2 at Connecticut's fuel-combustion point and 
nonpoint sources.

[[Page 21353]]

    Fourth, using the universe of information identified in steps 1-3 
(i.e., emissions sources, spatial scale and available data, modeling 
results and enforceable regulations), EPA then conducted an analysis 
under CAA section 110(a)(2)(D)(i)(I) to evaluate whether or not fuel-
combustion sources in Connecticut would significantly contribute to 
nonattainment in other states, and then whether they would interfere 
with maintenance of the NAAQS in other states.
    Based on the analysis provided by the state in its SIP submission 
and EPA's assessment of the information in that submittal for each of 
the factors discussed at length below in this action, EPA proposes to 
find that sources or emissions activity within Connecticut will not 
contribute significantly to nonattainment, nor will they interfere with 
maintenance of, the 2010 primary SO2 NAAQS in any other 
state.

III. Section 110(a)(2)(D)(i)(I)--Interstate Transport

A. General Requirements and Historical Approaches for Criteria 
Pollutants

    Section 110(a)(2)(D)(i)(I) requires SIPs to include provisions 
prohibiting any source or other type of emissions activity in one state 
from emitting any air pollutant in amounts that will contribute 
significantly to nonattainment, or interfere with maintenance, of the 
NAAQS in another state. The two clauses of this section are referred to 
as prong 1 (significant contribution to nonattainment) and prong 2 
(interference with maintenance of the NAAQS).
    EPA's most recent infrastructure SIP guidance, the September 13, 
2013 ``Guidance on Infrastructure State Implementation Plan (SIP) 
Elements under Clean Air Act Sections 110(a)(1) and 110(a)(2),'' did 
not explicitly include criteria for how the Agency would evaluate 
infrastructure SIP submissions intended to address section 
110(a)(2)(D)(i)(I).\2\ With respect to certain pollutants, such as 
ozone and particulate matter, EPA has addressed interstate transport in 
eastern states in the context of regional rulemaking actions that 
quantify state emission reduction obligations.\3\ In other actions, 
such as EPA action on western state SIPs addressing ozone and 
particulate matter, EPA has considered a variety of factors on a case-
by-case basis to determine whether emissions from one state interfere 
with the attainment and maintenance of the NAAQS in another state. In 
such actions, EPA has considered available information such as current 
air quality, emissions data and trends, meteorology, and topography.\4\
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    \2\ At the time the September 13, 2013 guidance was issued, EPA 
was litigating challenges raised with respect to its Cross State Air 
Pollution Rule (``CSAPR''), 76 FR 48208 (Aug. 8, 2011), designed to 
address the CAA section 110(a)(2)(D)(i)(I) interstate transport 
requirements with respect to the 1997 ozone and the 1997 and 2006 
PM2.5 NAAQS. CSAPR was vacated and remanded by the D.C. 
Circuit in 2012 pursuant to EME Homer City Generation, L.P. v. EPA, 
696 F.3d 7. EPA subsequently sought review of the D.C. Circuit's 
decision by the Supreme Court, which was granted in June 2013. As 
EPA was in the process of litigating the interpretation of section 
110(a)(2)(D)(i)(I) at the time the infrastructure SIP guidance was 
issued, EPA did not issue guidance specific to that provision. The 
Supreme Court subsequently vacated the D.C. Circuit's decision and 
remanded the case to that court for further review. 134 S.Ct. 1584 
(2014). On July 28, 2015, the D.C. Circuit issued a decision 
upholding CSAPR, but remanding certain elements for reconsideration. 
795 F.3d 118.
    \3\ NOX SIP Call, 63 FR 57371 (October 27, 1998); 
Clean Air Interstate Rule (CAIR), 70 FR 25172 (May 12, 2005); CSAPR, 
76 FR 48208 (August 8, 2011).
    \4\ See, e.g., Approval and Promulgation of Implementation 
Plans; State of California; Interstate Transport of Pollution; 
Significant Contribution to Nonattainment and Interference With 
Maintenance Requirements, Proposed Rule, 76 FR 146516, 14616-14626 
(March 17, 2011); Final Rule, 76 FR 34872 (June 15, 2011); Approval 
and Promulgation of State Implementation Plans; State of Colorado; 
Interstate Transport of Pollution for the 2006 24-Hour 
PM2.5 NAAQS, Proposed Rule, 80 FR 27121, 27124-27125 (May 
12, 2015); Final Rule, 80 FR 47862 (August 10, 2015).
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    For other pollutants such as Pb, EPA has suggested the applicable 
interstate transport requirements of section 110(a)(2)(D)(i)(I) can be 
met through a state's assessment as to whether or not emissions from Pb 
sources located in close proximity to its borders have emissions that 
impact a neighboring state such that they contribute significantly to 
nonattainment or interfere with maintenance in that state. For example, 
EPA noted in an October 14, 2011 memorandum titled, ``Guidance on 
Infrastructure SIP Elements Required Under Sections 110(a)(1) and 
110(a)(2) for the 2008 Pb NAAQS,'' \5\ that the physical properties of 
Pb prevent its emissions from experiencing the same travel or formation 
phenomena as PM2.5 or ozone, and there is a sharp decrease 
in Pb concentrations, at least in the coarse fraction, as the distance 
from a Pb source increases. Accordingly, while it may be possible for a 
source in a state to emit Pb in a location and in quantities that may 
contribute significantly to nonattainment in, or interfere with 
maintenance by, any other state, EPA anticipates that this would be a 
rare situation, e.g., where large sources are in close proximity to 
state boundaries.\6\ Our rationale and explanation for approving the 
applicable interstate transport requirements under section 
110(a)(2)(D)(i)(I) for the 2008 Pb NAAQS, consistent with EPA's 
interpretation of the October 14, 2011 guidance document, can be found 
among other instances, in the proposed approval and a subsequent final 
approval of interstate transport SIPs submitted by Illinois, Michigan, 
Minnesota, and Wisconsin.\7\
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    \5\ https://www3.epa.gov/ttn/naaqs/aqmguide/collection/cp2/20111014_page_lead_caa_110_infrastructure_guidance.pdf.
    \6\ Id. at pp 7-8.
    \7\ See 79 FR 27241 at 27249 (May 13, 2014) and 79 FR 41439 
(July 16, 2014).
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B. Approach for Addressing the Interstate Transport Requirements of the 
2010 Primary SO2 NAAQS in Connecticut

    As previously noted, section 110(a)(2)(D)(i)(I) requires an 
evaluation of any source or other type of emissions activity in one 
state and how emissions from these source categories may impact air 
quality in other states. The EPA believes that a reasonable starting 
point for determining which sources and emissions activities in 
Connecticut are likely to impact downwind air quality with respect to 
the SO2 NAAQS is by using information in the NEI.\8\ The NEI 
is a comprehensive and detailed estimate of air emissions of criteria 
pollutants, criteria precursors, and hazardous air pollutants from air 
emissions sources, and is updated every three years using information 
provided by the states. At the time of this rulemaking, the most 
recently available dataset is the 2014 NEI, and the state summary for 
Connecticut is included in the table below.
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    \8\ https://www.epa.gov/air-emissions-inventories/national-emissions-inventory.

          Table 1--Summary of 2014 NEI SO2 Data for Connecticut
------------------------------------------------------------------------
                                                               Emissions
                          Category                             (tons per
                                                                 year)
------------------------------------------------------------------------
Fuel Combustion: Electric Utilities.........................       1,511
Fuel Combustion: Industrial.................................         759
Fuel Combustion: Other......................................       9,170
Waste Disposal and Recycling................................         466
Highway Vehicles............................................         267
Off-Highway.................................................         244
Miscellaneous...............................................           8
                                                             -----------
    Total...................................................      12,425
------------------------------------------------------------------------

    The EPA observes that according to the 2014 NEI, the vast majority 
of SO2 emissions in Connecticut originate from fuel 
combustion at point and nonpoint sources. Therefore, an assessment of

[[Page 21354]]

Connecticut's satisfaction of all applicable requirements under section 
110(a)(2)(D)(i)(I) of the CAA for the 2010 SO2 NAAQS may be 
reasonably based upon evaluating the downwind impacts of emissions from 
the combined fuel combustion categories (i.e., electric utilities, 
industrial processes, and other sources \9\).
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    \9\ The ``other'' category of fuel combustion in Connecticut is 
comprised almost entirely of residential heating through fuel oil 
combustion.
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    The definitions contained in appendix D to 40 CFR part 58 are 
helpful indicators of the travel and formation phenomenon for 
SO2 in its stoichiometric gaseous form in the context of the 
2010 primary SO2 NAAQS originating from stationary sources. 
Notably, section 4.4 of this appendix titled, ``Sulfur Dioxide 
(SO2) Design Criteria'' provides definitions for 
SO2 Monitoring Spatial Scales for microscale, middle scale, 
neighborhood, and urban scale monitors. The microscale includes areas 
in close proximity to SO2 point and area sources, and extend 
approximately 100 meters from a facility. The middle scale generally 
represents air quality levels in areas 100 meters to 500 meters from a 
facility, and may include locations of maximum expected short-term 
concentrations due to proximity of major SO2 point, area, 
and non-road sources. The neighborhood scale characterizes air quality 
conditions between 0.5 kilometers and 4 kilometers from a facility, and 
emissions from stationary and point sources may under certain plume 
conditions, result in high SO2 concentrations at this scale. 
Lastly, the urban scale is used to estimate concentrations over large 
portions of an urban area with dimensions of 4 to 50 kilometers from a 
facility, and such measurements would be useful for assessing trends 
and concentrations in area-wide air quality, and hence, the 
effectiveness of large-scale pollution control strategies. Based on 
these definitions contained in EPA's own regulations, we believe that 
it is appropriate to examine the impacts of emissions from electric 
utilities and industrial processes in Connecticut in distances ranging 
from 0 km to 50 km from the facility. In other words, SO2 
emissions from stationary sources in the context of the 2010 primary 
NAAQS do not exhibit the same long-distance travel, regional transport 
or formation phenomena as either ozone or PM2.5, but rather, 
these emissions behave more like Pb with localized dispersion. 
Therefore, an assessment up to 50 kilometers from potential sources 
would be useful for assessing trends and SO2 concentrations 
in area-wide air quality.\10\ Based on the fact that SO2 
emissions from residential fuel combustion consists of 73% of all 
SO2 emissions in the NEI, EPA believes it is reasonable to 
evaluate any regulations intended to address fuel oil, specifically 
with respect to the sulfur content in order to determine interstate 
transport impacts from the category of ``other'' sources of fuel 
combustion.
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    \10\ EPA recognizes in Appendix A.1 titled, ``AERMOD (AMS/EPA 
Regulatory Model)--'' of appendix W to 40 CFR part 51 that the model 
is appropriate for predicting SO2 up to 50 kilometers.
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    Our current implementation strategy for the 2010 primary 
SO2 NAAQS includes the flexibility to characterize air 
quality for stationary sources via either data collected at ambient air 
quality monitors sited to capture the points of maximum concentration, 
or air dispersion modeling.\11\ Our assessment of SO2 
emissions from fuel combustion categories in the state and their 
potential on neighboring states are informed by all available data at 
the time of this rulemaking, and include: SO2 ambient air 
quality; SO2 emissions and SO2 emissions trends; 
SIP-approved SO2 regulations and permitting requirements; 
available air dispersion modeling; and, other SIP-approved or Federally 
promulgated regulations which may yield reductions of SO2. 
This notice describes EPA's evaluation of Connecticut's May 30, 2013 
infrastructure SIP submission to satisfy the requirements of CAA 
section 110(a)(2)(D)(i)(I).\12\
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    \11\ https://www.epa.gov/so2-pollution/2010-1-hour-sulfur-dioxide-so2-primary-national-ambient-air-quality-standards-naaqs.
    \12\ EPA notes that the evaluation of other states' satisfaction 
of section 110(a)(2)(D)(i)(I) for the 2010 SO2 NAAQS can 
be informed by similar factors found in this proposed rulemaking, 
but may not be identical to the approach taken in this or any future 
rulemaking for Connecticut, depending on available information and 
state-specific circumstances.
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C. Prong 1 Analysis--Significant Contribution to Nonattainment

    Prong 1 of the good neighbor provision requires state plans to 
prohibit emissions that will significantly contribute to nonattainment 
of a NAAQS in another state. In order to evaluate Connecticut's 
satisfaction of prong 1, EPA evaluated the state's SIP submission with 
respect to the following four factors: (1) SO2 ambient air 
quality and emissions trends for Connecticut and neighboring states; 
(2) potential ambient impacts of SO2 emissions from certain 
facilities in Connecticut on neighboring states based on available air 
dispersion modeling results; (3) SIP-approved regulations specific to 
SO2 emissions and permit requirements; and (4) other SIP-
approved or Federally enforceable regulations that, while not directly 
intended to address or reduce SO2 emissions, may yield 
reductions of the pollutant. A detailed discussion of each of these 
factors is below.
1. SO2 Emissions Trends
    Connecticut's infrastructure SIP submission refers to EPA's 
previous designation efforts for the 2010 SO2 NAAQS. In 
particular, Connecticut explains that on February 7, 2013, EPA 
transmitted a letter to the state observing that, based on ambient air 
quality data collected between 2009 and 2011, no monitored violations 
of the 2010 SO2 NAAQS had been recorded in Connecticut.\13\ 
Additionally, the state references a technical support document it 
submitted with its SIP titled, ``Technical Justification to Support a 
Designation of Attainment of the 1-hour Sulfur Dioxide (SO2) 
NAAQS for Connecticut'' (hereafter referred to as the Technical 
Justification), which includes state-specific information about ambient 
monitoring data, large sources of SO2, and air dispersion 
modeling.\14\ Where applicable, supporting information from the 
Technical Justification will be referenced in the discussions below.
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    \13\ On August 5, 2013, EPA promulgated final nonattainment 
designations for 29 areas in 16 states in which monitors had 
recorded violations of the 2010 SO2 NAAQS, based on data 
from 2009-2011. See 78 FR 47191. As Connecticut contained no such 
areas, no areas in Connecticut were designated in that action. The 
EPA is now subject to a court order to complete designations under 
the NAAQS for the rest of the nation, including Connecticut. 
However, as of the date of this notice EPA has not designated any 
areas in Connecticut under the 2010 SO2 NAAQS.
    \14\ See http://www.ct.gov/deep/lib/deep/air/so2/so2_designation_tsd_final_13mar2013.pdf.
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    As noted above, EPA's approach for addressing the interstate 
transport of SO2 in Connecticut is based upon emissions from 
fuel combustion at electric utilities, industrial sources, and 
residential heating. As part of the Technical Justification document, 
Connecticut observed that, in accordance with the most recently 
available designations guidance at the time,\15\ there were four 
facilities (all electric utilities) in Connecticut with reported actual 
emissions greater than or equal to 100 tons per year (tpy) of 
SO2 in any given year between 2009 and 2011. The four 
facilities and each facility's maximum SO2 emissions in

[[Page 21355]]

any one year between 2009 and 2011 are presented in the table below.
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    \15\ March 24, 2011 guidance document titled, ``Area 
Designations for the 2010 Revised Primary Sulfur Dioxide National 
Ambient Air Quality Standards.'' See, e.g. http://dnr.wi.gov/topic/AirQuality/documents/SO2DesignationsGuidance2011.pdf.

    Table 2--Connecticut Facilities With Emissions in Any Single Year
 Between 2009-2011 Exceeding 100 tons per year (tpy), as Provided in the
                     State's Technical Justification
------------------------------------------------------------------------
                                                         Highest yearly
                                                         SO2 emissions
                                                         (tpy) between
                    Facility name                        2009 and 2011
                                                          (state point
                                                       source inventory)
------------------------------------------------------------------------
Middletown Power.....................................              235.2
Norwalk Power *......................................              489.0
PSEG Power New Haven.................................              216.9
PSEG Power BPT Harbor................................            2,974.6
                                                      ------------------
    Total............................................            3,915.7
------------------------------------------------------------------------
* Norwalk Power is included in this summary because it was part of the
  state's Technical Justification. The facility was deactivated on June
  1, 2013, and the permit was officially revoked in November 2013.

    While the information in Table 2 provides the highest yearly 
SO2 emissions between 2009 and 2011 based on the state point 
source inventory, an emissions summary for all electric utilities 
within the state subject to the federal Acid Rain Program will help 
determine whether the emissions from the facilities above can be relied 
upon as a general indicator of state-wide SO2 emissions from 
all electric utilities. Data for this purpose can be found in the most 
recent EPA Air Markets Program Data (2016 AMPD).\16\ The 2016 AMPD is 
an application that provides both current and historical data collected 
as part of EPA's emissions trading programs. A summary of all 2016 
SO2 emissions from electric utilities in Connecticut subject 
to the Acid Rain Program is below.
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    \16\ https://ampd.epa.gov/ampd/.

 Table 3--2016 AMPD Data for All Connecticut Electric Utilities in tons
                             per year (tpy)
------------------------------------------------------------------------
                                                              2016 AMPD
                       Facility name                             data
------------------------------------------------------------------------
PSEG Power BPT Harbor......................................        238.8
Middletown Power...........................................         29.8
PSEG Power New Haven.......................................         29.3
Montville Station..........................................         26.1
Lake Road Generating Company...............................         11.9
Kleen Energy Systems Project...............................          8.5
Bridgeport Energy..........................................          7.8
Milford Power Company, LLC.................................          6.9
Waterbury Generation.......................................          1.3
Wallingford Energy, LLC....................................          0.6
Devon......................................................          0.3
Capitol District Energy Center.............................          0.3
Alfred L Pierce Generating Station.........................          0.0
                                                            ------------
    Total..................................................        361.6
------------------------------------------------------------------------

    Table 3 provides several key pieces of information. First, the 
emissions from the still-operational facilities referenced in the 
state's Technical Justification have decreased significantly compared 
to the historical high level during the 2009 to 2011 time period. The 
combined emissions from PSEG Power BPT Harbor, PSEG Power New Haven, 
and Middletown Power were 3,426.7 tons according to the state point 
source inventory during the highest year between for 2009-2011, whereas 
the 2016 AMPD data indicate that the combined emissions from these same 
facilities is slightly less than 300 tons. Additionally, the combined 
emissions from the still operational facilities referenced in the 
Technical Justification from the state point source inventory between 
2009-2011 is significantly higher than the combined 2016 AMPD emissions 
from all electric utilities, indicating that the overall SO2 
emissions from large sources (such as electric generating units) within 
Connecticut has decreased substantially between 2009 and the time of 
this rulemaking. Lastly, according to the 2016 AMPD, SO2 
emissions from the still-operational facilities referenced in the 
Technical Justification account for the vast majority of the 
SO2 emissions from all electric utilities in the state; 
therefore, EPA believes that any assessment of SO2 emissions 
from electric utilities in the state may be informed by the emissions 
from PSEG Power BPT Harbor, PSEG Power New Haven, and Middletown Power. 
As previously noted, Norwalk Power was deactivated on June 1, 2013, and 
the permit for the facility was officially revoked in November 2013.
2. SO2 Ambient Air Quality
    Data collected at ambient air quality monitors indicate the 
monitored values of SO2 in the state have remained below the 
NAAQS. Relevant data from AQS Design Value (DV) \17\ reports for recent 
and complete 3-year periods are summarized in the table below.
---------------------------------------------------------------------------

    \17\ A ``Design Value'' is a statistic that describes the air 
quality status of a given location relative to the level of the 
NAAQS. The interpretation of the primary 2010 SO2 NAAQS 
(set at 75 parts per billion (ppb)) including the data handling 
conventions and calculations necessary for determining compliance 
with the NAAQS can be found in appendix T to 40 CFR part 50.

                   Table 4--Trend in SO2 Design Values in ppb for AQS Monitors in Connecticut
----------------------------------------------------------------------------------------------------------------
                                                                                 2009-2011  2011-2013  2013-2015
               AQS monitor site                        Monitor location          DV  (ppb)  DV  (ppb)  DV  (ppb)
----------------------------------------------------------------------------------------------------------------
09-001-0012..................................  Edison School, Bridgeport.......         20         14          9
09-005-0005..................................  Mohawk Mountain, Cornwall.......        (*)          7          5

[[Page 21356]]

 
09-009-0027..................................  Criscuolo Park, New Haven.......         36         23         13
----------------------------------------------------------------------------------------------------------------
* The design value for this site is invalid due to incomplete data for these years and not for use in comparison
  to the NAAQS.

    As shown in Table 4 above, the DVs for the two monitoring sites for 
which there are complete data for all years between 2009 and 2015 have 
decreased between each of the 3-year blocks shown in the table. The 
highest valid DV in Connecticut for 2013-2015 is 13 ppb, which is well 
below the NAAQS.
    It is not known whether the monitors in Table 4 were sited to 
capture points of maximum impact from PSEG Power BPT Harbor, PSEG Power 
New Haven, and Middletown Power. The monitoring information, when 
considered alone, might not support a conclusion that the areas most 
impacted by these sources are attaining the NAAQS when considered in 
the context of the spatial scales defined in the background section of 
this rulemaking.

  Table 5--Distances Between Still-Operational Electric Utilities in Connecticut's Technical Justification and
                                Regulatory Monitors With Complete 2013-2015 Data
----------------------------------------------------------------------------------------------------------------
                                               Distance to
                                               closest AQS                                         2013-2015 DV
                  Facility                    monitor in CT             Spatial scale                  (ppb)
                                                  (km)
----------------------------------------------------------------------------------------------------------------
PSEG Power BPT Harbor......................             3.2  Neighborhood.......................               9
PSEG Power New Haven.......................             1.5  Neighborhood.......................              13
Middletown Power...........................            37.5  Urban..............................              13
----------------------------------------------------------------------------------------------------------------

    Table 5 indicates that while the monitors closest to PSEG Power BPT 
Harbor (AQS Site ID 09-001-0012) and PSEG New Haven (AQS Site ID 09-
009-0027) may not be sited in the area to capture points of maximum 
concentration from the facilities, the monitors are located in the 
neighborhood spatial scale in relation to the facilities, i.e., 
emissions from stationary and point sources may under certain plume 
conditions, result in high SO2 concentrations at this scale. 
Forty CFR part 58, appendix D, section 4.4.4(3) defines neighborhood 
scale as ``[t]he neighborhood scale would characterize air quality 
conditions throughout some relatively uniform land use areas with 
dimensions in the 0.5 to 4.0 kilometer range.'' The closest AQS monitor 
to Middletown Power with complete 2013-2015 data (AQS Site ID 09-009-
0027) would be considered an urban scale monitor when compared to the 
location of the facility. The most recently available DVs based on 
2013-2015 at all three monitors are well below the NAAQS.
    However, the absence of a violating ambient air quality monitor 
within the state is insufficient to demonstrate that Connecticut has 
met its interstate transport obligation. While the decreasing DVs and 
their associated spatial scales support the notion that emissions 
originating within Connecticut are not contributing to a violation of 
the NAAQS within the state, prong 1 of section 110(a)(2)(D)(i)(I) 
specifically addresses the effects that sources within Connecticut have 
on air quality in neighboring states. Therefore, an evaluation and 
analysis of SO2 emissions data from facilities within the 
state, together with the potential effects of such emissions on ambient 
data in neighboring states, is appropriate.
    As previously discussed, EPA's definitions of spatial scales for 
SO2 monitoring networks indicate that the maximum impacts 
from stationary sources can be expected within 4 kilometers of such 
sources, and that distances up to 50 kilometers would be useful for 
assessing trends and concentrations in area-wide air quality. The only 
nearby state within 50 km of any of the currently operating facilities 
in Connecticut is New York; all other areas within 50 km of these 
facilities are contained within Connecticut's borders.\18\ As a result, 
no further analysis of the other neighboring states (Rhode Island and 
Massachusetts) or any other states is necessary for assessing the 
impacts of the interstate transport of SO2 pollution from 
these facilities.
---------------------------------------------------------------------------

    \18\ New Jersey is within 50 km of Norwalk Power, but as 
previously mentioned, the facility was deactivated in June 2013, and 
its permit was revoked in November 2013. As a result, its current 
and future emissions are effectively zero and EPA does not believe 
that its emissions are contributing to a violation of the NAAQS in 
New Jersey.
---------------------------------------------------------------------------

3. SO2 Air Dispersion Modeling
    As discussed in the Section I of this rulemaking, EPA's current 
approach for implementing the 2010 primary SO2 NAAQS 
provides the flexibility to characterize air quality from stationary 
sources through either air dispersion modeling or ambient air quality 
monitors that have been sited to capture the points of maximum 
concentration. EPA observes that Appendix A.1 titled, ``AERMOD (AMS/EPA 
Regulatory Model)'' of appendix W to 40 CFR part 51 is appropriate for 
SO2 in instances where transport distances over which 
steady-state assumptions are appropriate, up to 50 kilometers. While 
not written specifically to address interstate transport, the 50 
kilometer range in AERMOD aligns with the urban monitoring scale, and 
thus, EPA believes that the use of AERMOD provides a reliable 
indication of air quality for transport purposes. In order to further 
analyze the impact of certain electric utilities in Connecticut on air 
quality in neighboring states, the state performed air dispersion 
modeling using emissions data from 2009-2011, which reflects emissions 
from PSEG Power Bridgeport Harbor, PSEG Power New Haven, and Middletown 
Power, as well as the now deactivated Norwalk Power Station. As 
previously discussed, each of these facilities emitted at least 100 tpy 
of SO2 or more in any given year between 2009 and 2011, and 
based on the 2016 AMPD, the emissions from the

[[Page 21357]]

still-operational facilities account for almost 80% of the total 
SO2 emissions from all electric utilities in Connecticut 
subject to the Acid Rain Program.
    The state performed the air dispersion modeling using the most 
recent version of the AERMOD modeling system available at the time, 
which included the dispersion model AERMOD (version 12345), along with 
its pre-processor modules AERMINUTE, AERMET, AERSURFACE, and AERMAP. A 
discussion of the state's procedures and results follows below, with 
references to EPA's ``SO2 NAAQS Designations Modeling 
Technical Assistance Document'' (Modeling TAD), most recently updated 
in August 2016, as appropriate. The EPA observes that while the 
Modeling TAD is intended to assist states and other interested parties 
in characterizing local air quality for designations purposes, these 
same methodologies can be used to determine whether SO2 
emissions from electric utilities in Connecticut are leading to 
exceedances of the NAAQS in a neighboring state. As a result of the 
localized dispersion pattern and ranges of expected maximum impacts of 
SO2 emissions from stationary sources in the context of the 
2010 primary NAAQS along with our current flexibility to characterize 
air quality through either properly sited monitors or air dispersion 
monitoring, EPA believes that the analysis performed by Connecticut for 
designations purposes is also adequate to address interstate transport 
requirements.
a. Emission Rates and Modeling Domain
    Individual unit emission rates modeled at the four facilities 
reflected either the allowable hourly rates based on the maximum firing 
rate of the unit or hourly continuous emissions monitoring (CEM) data 
correlated with hourly meteorological data. In other words, Connecticut 
modeled actual emissions for units at each facility based on CEMs data 
where it was available, and modeled the allowable hourly rates for 
units at each facility where CEMs data was not available. EPA believes 
the use of actual and allowable emissions adequately represented 
operating conditions at the time of Connecticut's overall 
infrastructure SIP submission, and therefore the modeled concentrations 
adequately characterized air quality with respect to emissions from the 
four facilities.
    Furthermore, the overall SO2 emissions levels in 
Connecticut from these four sources are declining, and the higher 
emissions levels reflected in the state's modeling analysis represent a 
conservative estimate of future emissions from these facilities. In 
particular, EPA expects continued lower emissions from these four 
facilities as a result of Norwalk Power's closure and permit 
revocation, along with the measures contained in Regulations of 
Connecticut State Agencies (RCSA) Section 22a-174-19a \19\ intended to 
limit SO2 emissions within the state. The EPA believes that 
the 2016 AMPD data presented in Table 3, which shows an overall 
decrease at each facility, adequately characterizes the extent of these 
sources' contribution to future air quality in the area.\20\
---------------------------------------------------------------------------

    \19\ EPA published the final rulemaking approving RCSA Section 
22a-174-19a on July 10, 2014 (79 FR 39322).
    \20\ The Modeling TAD notes that the most recent three years of 
actual emissions should be used, and as part of this analysis CT 
used 2009-2011 emissions which are significantly higher than the 
2016AMPD actual emissions data.
---------------------------------------------------------------------------

    To develop the receptor networks for the modeling domains, the 
state used the AERMOD terrain pre-processor AERMAP. EPA's recommended 
procedure for characterizing an area by prevalent land use is based on 
evaluating the dispersion environment within 3 kilometers of the 
facility. According to EPA's modeling guidelines contained in documents 
such as the Modeling TAD, rural dispersion coefficients are to be used 
in the dispersion modeling analysis if more than 50% of the area within 
a 3 km radius of the facility is classified as rural. Conversely, if 
more than 50% of the area is urban, urban dispersion coefficients 
should be used in the modeling analysis. Consistent with these 
guidelines, the state modeled three of the facilities using urban 
dispersion, i.e., PSEG Power New Haven, PSEG Power BPT Harbor, and 
Norwalk Power, and one facility using rural dispersion, i.e., 
Middletown.
    The modeling domain for each facility consisted of a Cartesian grid 
centered around the facility with each side measuring 100 km, i.e., 50 
km from the center of the grid in length. Consistent with the best 
practices contained in the Modeling TAD, the state's receptors for 
modeling were placed as follows: 250 meter spacing from the center to 2 
km from the center of the grid; 500 meter spacing from 2 km to 10 km 
from the center of the grid; 1 km spacing from 10 km to 20 km from the 
center of the grid; and, 2 km spacing from 20 km to 50 km from the 
center of the grid. The extent of each facility's domain into counties 
in New York and New Jersey is summarized in the table below.

   Table 6--Neighboring States and Counties Included in the Modeling Domains of Certain Connecticut Facilities
                               [Y indicates the county is included in that domain]
----------------------------------------------------------------------------------------------------------------
                                                 Middletown    PSEG Power  New  PSEG Power  BPT
  Extent of modeling domain county (state)         Power            Haven            Harbor       Norwalk  Power
----------------------------------------------------------------------------------------------------------------
Bergen (New Jersey).........................  ...............  ...............  ...............               Y
Bronx (New York)............................  ...............               Y   ...............               Y
Dutchess (New York).........................  ...............               Y   ...............               Y
Hudson (New Jersey).........................  ...............  ...............  ...............               Y
Kings (New York)............................  ...............  ...............  ...............               Y
Nassau (New York)...........................  ...............               Y                Y                Y
New York (New York).........................  ...............  ...............  ...............               Y
Orange (New York)...........................  ...............  ...............  ...............               Y
Putnam (New York)...........................  ...............               Y   ...............               Y
Queens (New York)...........................  ...............               Y   ...............               Y
Richmond (New York).........................  ...............  ...............  ...............               Y
Rockland (New York).........................  ...............  ...............  ...............               Y
Suffolk (New York)..........................               Y                Y                Y                Y
Ulster (New York)...........................  ...............  ...............  ...............               Y

[[Page 21358]]

 
Westchester (New York)......................  ...............               Y   ...............               Y
----------------------------------------------------------------------------------------------------------------

b. Meteorology and Background Air Quality
    As part of its technical justification for the designation process, 
Connecticut provided EPA with access to AERMOD-ready five-year 
meteorological data processed through AERMET. These datasets were 
generated from National Weather Service Automated Surface Observing 
System (ASOS) stations in the state and upper air sounding data at 
either Albany, New York or Brookhaven, New York. The state used 
Integrated Surface Hourly Data (ISHD for surface observations), as well 
as archived one-minute data pre-processed through AERMINUTE, which uses 
the archived one-minute wind data to develop hourly average wind speed 
and wind direction for use in AERMET. The meteorological databases used 
by the state for each of the 4 facilities are summarized in the table 
below.

   Table 7--Meteorological Databases for Each Facility/Modeling Domain
  Provided in Connecticut's Technical Justification for the Designation
                                 Process
------------------------------------------------------------------------
                                         Meteorological database  (2007-
        Facility/modeling domain                      2011)
------------------------------------------------------------------------
Middletown Power.......................  Surface: Bradley Airport
                                         Upper Air: Albany, New York
------------------------------------------------------------------------
Norwalk Power..........................  Surface: Sikorsky Airport
PSEG Power New Haven...................  Upper Air: Brookhaven
PSEG Power BPT Harbor..................
------------------------------------------------------------------------

    The EPA notes that, consistent with the Modeling TAD, the most 
recent years of meteorological data at the time were used in the 
state's modeling.
    Consistent with EPA's March 1, 2011 memorandum titled, ``Additional 
Clarification Regarding Application of Appendix W Modeling Guidance for 
the 1-hour NO2 National Ambient Air Quality Standard,'' 
Connecticut developed background values from hourly SO2 
levels measured by Federal Reference Method (FRM) equivalent monitors 
located throughout the state. The FRM monitors corresponding to each of 
the facilities' modeling domain are listed in the table below.

   Table 8--Background Air Quality Monitoring Sites for Each Facility/
  Modeling Domain Provided in Connecticut's Technical Justification for
                         the Designation Process
------------------------------------------------------------------------
                              Monitor location for      Corresponding
    AQS monitor site for         background air       facility/modeling
   background air quality            quality               domain
------------------------------------------------------------------------
09-001-0012.................  Edison School,        Middletown Power
                               Bridgeport.
09-003-1003.................  McAuliffe Park, East  Norwalk Power and
                               Hartford.             PSEG Power BPT
                                                     Harbor
09-009-0027.................  Criscuolo Park, New   PSEG Power New Haven
                               Haven.
------------------------------------------------------------------------

    In the development of background concentrations, the state adopted 
what is referred to as a ``Tier II'' approach: A multi-year average of 
2nd high measured 1-hour concentrations of each season and hour-of-day 
combinations from 2009-2011. These concentrations represent 
SO2 emissions from out-of-state transport, as well as local/
state point, area, and mobile source emissions that were not explicitly 
modeled. These background concentrations were included in Connecticut's 
final AERMOD modeling results for the four facilities emitting at or 
above 100 tpy in any given year between 2009 and 2011. The ``Tier II'' 
approach adopted by the state for incorporating background 
concentration into the total modeled impacts from the four facilities 
is consistent with EPA guidelines. Furthermore, EPA notes that the 
emissions from any un-modeled large emissions sources which emit 
SO2 through fuel combustion can be adequately represented 
through the calculated background concentrations because of their low 
emissions. As shown in Table 3, the remaining SO2 emissions 
from all electric utilities in Connecticut subject to the Acid Rain 
Program sum to only 63.7 tons, and the largest of these facilities, 
Montville Station (26.1 tpy), is approximately 70 kilometers away from 
the closest modeled facility. Based on these low emissions and distance 
from any of the modeled domains, EPA does not believe that emissions 
from Montville Station have the potential to alter the concentration 
gradient around the modeled sources. In a similar manner, EPA does not 
believe that the remaining 37.6 tpy of SO2 from the 
remaining electric utilities subject to the Acid Rain Program, ranging 
from just 11.9 tons per year to almost 0 tons per year, have the 
potential to alter the concentration gradient around the modeled 
sources. While data is not available for any year after the 2014 NEI 
for SO2 emissions as

[[Page 21359]]

a result of fuel combustion at industrial processes, EPA believes that 
based on all available information, these emissions do not have the 
potential to alter the concentration gradient around the modeled 
sources, and can therefore be adequately represented as background 
concentration. Specifically, the 2014 NEI lists the sum of these 
industrial processes with fuel combustion leading to SO2 
emissions as approximately 759 tons. See Table 1. EPA has confirmed 
these industrial processes are not centralized in such a manner that 
all 759 tons are concentrated in one area.
i. Interpretation of Modeling Results
    Due to the proximity between Norwalk Power, PSEG Power BPT Harbor, 
and PSEG Power New Haven, the emissions units from all three facilities 
were included in each facility's modeling domain. Middletown Power 
emissions were modeled separately in the Middletown Power domain, and 
no other emission units were included in the Middletown Power domain. 
The modeling results, including the impacts of background 
concentration, are summarized in the table below.

Table 9--AERMOD Modeling Results Accounting for Background Concentration
  for Facilities in Connecticut Emitting at Least 100 tpy of SO2 in Any
Given Year Between 2009 and 2011 and the Corresponding Percentage of the
                             2010 SO2 NAAQS
------------------------------------------------------------------------
                                     4th high average
                                        1-hour SO2      Percent of 2010
                                      concentrations     SO2 NAAQS  (75
          Facility/domain             in micrograms       ppb or 196.0
                                     per cubic meter     [micro]g/m\3\)
                                    ([micro]g/m\3\) *
------------------------------------------------------------------------
Middletown Power..................               89.7               45.7
Norwalk Power.....................               88.1               44.9
PSEG Power New Haven..............               87.5               44.6
PSEG Power BPT Harbor.............              159.0               81.1
------------------------------------------------------------------------
* It should be noted that these modeled results are expressed in
  [micro]g/m\3\; the 2010 SO2 NAAQS set at 75 ppb is approximately
  equivalent to 196 [micro]g/m\3\

    Table 9 above shows that the highest modeled concentration of 
SO2 for areas within the modeling domain (including areas 
outside of Connecticut) of the four facilities in Connecticut emitting 
at least 100 tpy of SO2 in any given year between 2009 and 
2011 is 159 [micro]g/m\3\, which corresponds to slightly over 80% of 
the 2010 SO2 NAAQS (set at 75 ppb or approximately 196 
[micro]g/m\3\). This value was modeled at the PSEG Power BPT Harbor 
domain, and can be attributed to the higher modeled emissions rate 
input than any of the other three facilities. As displayed above in 
Table 2, the PSEG Power BPT Harbor facility had the highest 
SO2 emissions according to the state provided point source 
inventory, and the facility also has the highest SO2 
emissions according to the 2014 NEI.
    As noted earlier, the emissions from all facility units except for 
Middletown Power were used in the modeling domains for Norwalk Power, 
PSEG Power BPT Harbor, and PSEG Power New Haven. The modeling results 
consistently demonstrate that the points of maximum impact for these 
three facilities, all of which are below the level of the 2010 
SO2 NAAQS, are located within 2.5 km of the center of each 
facility and are not located in neighboring states. Furthermore, the 
modeled concentrations of SO2 decrease dramatically to 
levels under 80 [micro]g/m\3\ (approximately 30.5 ppb, or 41% of the 
NAAQS) at a distance of no more than 10 km away from the center of each 
facility; therefore, the cumulative impacts from the three facilities' 
SO2 emissions are not expected to contribute to a violation 
of the 2010 SO2 NAAQS. It should also be noted that the 
modeled concentrations at each of these modeling domains are 
potentially over-estimating current impacts from the facilities because 
of the permanent closure and permit revocation of Norwalk Power, which 
occurred after Connecticut developed its Technical Justification for 
this submission.\21\
---------------------------------------------------------------------------

    \21\ Connecticut's technical justification was prepared and 
submitted to EPA in March, 2013, and as previously noted, EPA 
published its final approval of RCSA Section 22a-174-19a on July 10, 
2014 (79 FR 39322).
---------------------------------------------------------------------------

    The modeled results for Middletown Power indicate the maximum 
concentration of 89.7 [micro]g/m\3\, or approximately 34 ppb (45% of 
the NAAQS), is expected no more than 2.5 km from the center of the 
facility and are not located in neighboring states. Furthermore, 
modeled concentrations where the Middletown Power domain intersects 
with that of the closest facility (PSEG Power New Haven) specifically 
in areas encompassed by the town of North Branford, would be at most 
125 [micro]g/m\3\, or approximately 48 ppb (64% of the NAAQS). EPA 
believes that this cumulative value potentially overestimates the 
impacts of the facilities' emissions at the intersection of the domains 
because this value was obtained by adding the highest values in the 
range of concentrations corresponding to the modeling results at the 
intersection of the domains. As a result, EPA believes that the 
SO2 emissions from Middletown Power, when considered alone 
or in aggregate with the SO2 emissions from the PSEG Power 
North Haven domain, are not expected to contribute to a violation of 
the 2010 SO2 NAAQS either within or outside of the modeling 
domain.
ii. Modeled Results and Impacts on Neighboring States
    EPA believes that based on all available information at the time of 
this rulemaking, including the Technical Justification provided by the 
state, a reasonable way to estimate the impacts from SO2 
emissions as a result of electric utility or industrial fuel combustion 
originating in Connecticut on its neighboring states is to evaluate the 
following two factors in tandem: (1) The most recent and highest DV 
based on data collected from ambient air quality monitors in any county 
included in the individual domains for the four sources in Connecticut, 
i.e., the counties listed in Table 6; and, (2) the modeled 
concentrations from each of the facilities in the areas closest to the 
neighboring states. The approach described below combines the modeled 
impacts from the electric utilities and industrial processes in 
Connecticut without a background concentration with a reasonable 
background concentration in neighboring states to yield a final 
estimated impact that reflects projected air quality in those

[[Page 21360]]

neighboring states. The resultant calculated impacts support the notion 
that based on all available information, emissions from facilities in 
Connecticut are not contributing significantly to a violation of the 
NAAQS in neighboring states under a worst case scenario analysis.
    As noted in the discussion above, the modeled concentrations of 
SO2 originating from Norwalk Power, PSEG Power BPT Harbor, 
and PSEG Power New Haven (and representative of all electric utilities 
and industrial processes in Connecticut that emit SO2 as a 
result of fuel combustion) dramatically decrease after 2.5 km from the 
center of each facility, and at a distance of no more than 10 km from 
the center of each of these facilities the modeled concentrations are 
under 30.5 ppb. All emissions from the three sources were included in 
each individual facility's modeling domain. Therefore, EPA believes 
that 30.5 ppb is a reasonable value that represents the worst-case 
potential combined contribution from any electric utility or industrial 
process in Connecticut which emits SO2 via fuel combustion 
on any neighboring county included in the modeling domains, 
particularly because Norwalk Power has ceased operation and its permit 
has been revoked following Connecticut's infrastructure SIP submission. 
This value includes background concentrations of SO2 
calculated by Connecticut using a Tier II approach, which consisted of 
the multi-year average of 2nd high measured 1-hour concentrations for 
each season and hour-of-day combination from 2009-2011. Although 
Connecticut's Technical Justification did not include the numerical 
background concentration value for each of the modeling domains, EPA 
believes that a reasonable background air quality concentration for any 
of the domains can be estimated using a Tier Ib approach, which 
consists of the 1-hour DV for the most recent 3-year period from 
ambient air quality monitors located in Connecticut. The lowest valid 
DV at any of the monitors listed above (AQS Site ID 09-001-0012) in 
Table 8 based on ambient air quality data collected between 2013 and 
2015 is 9 ppb. The worst-case potential combined contribution from the 
combined electric utilities and industrial processes on any neighboring 
county included in the modeling domain, not including background 
concentrations of SO2, can therefore be estimated to be 21.5 
ppb. Additionally, this 21.5 ppb value can be used to estimate the 
worst case impacts from these sources on any neighboring state, without 
taking into account the background concentrations of SO2 in 
those neighboring states.
    In order to estimate the worst case combined SO2 impacts 
from electric utilities and industrial processes in Connecticut on any 
neighboring state with an appropriate background concentration, EPA 
added the 21.5 ppb described above to the highest DV in each 
neighboring county included in the modeling domains for Norwalk Power, 
PSEG Power BPT Harbor, and PSEG Power New Haven. It should be noted 
that the DV in each neighboring county included in the modeling domains 
already includes a monitored background concentration of 
SO2, and therefore adding a worst case potential combined 
contribution from the 3 sources of 21.5 ppb using the process described 
above, instead of 30.5 ppb from the state's Technical Justification, 
eliminates the double counting of background SO2 
concentrations:

Table 10--Worst Case Combined SO2 Impacts From Norwalk Power, PSEG Power
       BPT Harbor, and PSEG Power New Haven on Neighboring States
------------------------------------------------------------------------
                                                           Superimposed
                                      2013-2015 county      worst case
    Neighboring county (state)         level DV  (ppb)      SO2 impact
                                                               (ppb)
------------------------------------------------------------------------
Bergen (New Jersey)...............  No monitors.........        \b\ 37.5
Bronx (New York)..................  16..................            37.5
Dutchess (New York)...............  5...................            26.5
Hudson (New Jersey)...............  7...................            28.5
Kings (New York)..................  No monitors.........        \b\ 37.5
Nassau (New York).................  Incomplete data.....        \a\ 37.5
New York (New York)...............  No monitors.........        \b\ 37.5
Orange (New York).................  No monitors.........        \b\ 37.5
Putnam (New York).................  6...................            27.5
Queens (New York).................  11..................            32.5
Richmond (New York)...............  No monitors.........        \b\ 37.5
Rockland (New York)...............  No monitors.........        \b\ 37.5
Suffolk (New York)................  Incomplete data.....        \a\ 37.5
Ulster (New York).................  No monitors.........        \b\ 37.5
Westchester (New York)............  No monitors.........        \b\ 37.5
------------------------------------------------------------------------
\a\ The design values for these sites are invalid due to incomplete data
  for partial years between 2013 and 2015; therefore, the worst case SO2
  impacts were calculated by adding the highest DV for any county listed
  in the table to 21.5 ppb. The resulting worst case scenario is for
  illustrative purposes only.
\b\ In the absence of ambient air quality monitors in the county, the
  worst case SO2 impacts were calculated by adding the highest DV for
  any county in the state listed in the table to 21.5 ppb. The resulting
  worst case scenario is for illustrative purposes only.

    As shown in Table 10, the estimated highest worst case 
SO2 concentrations for all contributing sources, given 
background combined with all of the potential effects of transport from 
Norwalk Power, PSEG Power BPT Harbor, and PSEG Power New Haven (also 
representative of all electric utilities and industrial processes in 
Connecticut that emit SO2 via fuel combustion) on 
neighboring states is no greater than 37.5 ppb, or approximately 50% of 
the NAAQS, and not contributing to a violation of the 2010 standard. 
This superimposed value includes a valid 2013-2015 DV (which is 
representative of background concentration) for the monitor in Bronx 
County, New York (AQS ID 36-005-0133), and modeled concentrations of 
SO2 that represent the worst case currently and the upper 
bound for projected future emissions from all electric utilities and 
industrial processes in Connecticut that emit SO2 through 
fuel combustion, one of which is no longer operating. After 
consideration of

[[Page 21361]]

these factors and based on all available information at the time of 
this rulemaking, and including an analysis of the worst case scenario 
including all relevant emissions sources, EPA does not believe that 
combined emissions from the two remaining operational facilities in 
Connecticut closest to New York and New Jersey, i.e., PSEG Power BPT 
Harbor and PSEG Power New Haven, would contribute significantly to a 
violation of the 2010 SO2 NAAQS anywhere in either New York 
or New Jersey.
    In a similar manner for Middletown Power, EPA observes that the 
modeling domain for the facility extends only into a small portion of 
Suffolk County, New York; all other areas in the modeling domain are 
contained within Connecticut's borders. PSEG Power New Haven is the 
only other modeled source where the modeling domain intersects the 
portion of the modeling domain in New York from Middletown Power. As 
described earlier, the predicted modeled concentration of 
SO2 at the intersection of the Middletown Power and the PSEG 
Power New Haven domains is no more than 48 ppb. Subtracting a 
reasonable estimate of background concentration of SO2 via a 
Tier 1b approach using the 1-hour design value for the latest 3-year 
period, the predicted modeled concentration of SO2 at the 
intersection of the two domains is 39 ppb. Therefore, the estimated 
worst case SO2 impact on Suffolk County, New York that 
superimposes the modeled SO2 concentrations from the 
intersection of the two modeling domains, and the 2013-2015 DV (which 
includes background) for Suffolk County, New York (AQS ID 36-103-0009) 
is 48 ppb, or approximately 64% of the NAAQS. EPA acknowledges that the 
2013-2015 DV for Suffolk County of 9 ppb is not valid for comparison to 
the NAAQS due to an incomplete dataset. Available data reported into 
AQS from the monitor between 2013 and 2015 indicates that the highest 
99th percentile 1-hour concentration of SO2 was 10 ppb. 
Thus, an even more conservative estimate of the worst case 
SO2 impact on Suffolk County, New York is 49 ppb, or 
approximately 65% of the NAAQS. Based on all available information at 
the time of this rulemaking, EPA therefore does not believe that 
sources or emissions activity originating from Middletown Power, when 
considered alone or along with those from PSEG Power New Haven, would 
contribute significantly to a violation of the 2010 SO2 
NAAQS in New York. Because the modeling results also adequately account 
for SO2 emissions originating from fuel combustion at all 
other electric utilities and industrial process, EPA does not believe 
that such facilities would contribute significantly to a violation of 
the 2010 SO2 NAAQS anywhere in New York.
    With respect to the potential transport impacts from sources or 
emissions activity originating in Connecticut on the neighboring states 
of Rhode Island and Massachusetts, EPA reiterates that all other areas 
within 50 km of the currently operating sources modeled by the state 
are contained within Connecticut's borders. In addition, the design 
value for 2015 for all SO2 monitors within Massachusetts and 
Rhode Island were below 75 ppb. The monitor with the highest design 
value in 2015 in either Rhode Island or Massachusetts was 28 ppb (37% 
of the standard) in Fall River, Massachusetts. As a result, no further 
analysis of these states is provided, nor does EPA believe that further 
analysis is needed to establish that SO2 emissions 
originating in Connecticut as a result of fuel combustion from electric 
utilities or industrial processes do not significantly contribute to 
nonattainment of the 1-hour SO2 NAAQS in those neighboring 
states.
4. SIP Approved Regulations Specific to SO2 and Permitting 
Requirements
    The state has various provisions and regulations to ensure that 
SO2 emissions are not expected to substantially increase in 
the future. Notably, federally enforceable conditions contained in RCSA 
Section 22a-174-19a, ``Control of sulfur dioxide emissions from power 
plants and other large stationary sources of air pollution,''apply to 
emissions at the four facilities outlined in the state's Technical 
Justification as well as other sources of SO2 emissions. 
Specifically, this SIP-approved regulation requires these four 
facilities, and some others such as fossil-fuel-fired boilers with a 
maximum heat input capacity of 250 MMBTU/hr or more, to limit their 
SO2 emissions by either meeting an SO2 emission 
limit of 0.33 lbs/MMBtu or limiting the amount of sulfur contained in 
any liquid or gas the facilities may burn to 0.3% sulfur by weight. The 
recently revised RSCA Section 22a-174-19b \22\ will limit those 
stationary sources that are not subject to RSCA 22a-174-19a to 
combusting residual fuel oil with a sulfur content of 0.3% or less by 
weight and distillate fuel oil of 0.0015% or less by weight by July 1, 
2018.
---------------------------------------------------------------------------

    \22\ See 81 FR 33134 (May 25, 2016).
---------------------------------------------------------------------------

    The 2014 NEI indicates the single largest, albeit diffuse, source 
category of SO2 emissions from Connecticut is from fuel 
combustion for residential heating, in excess of 9,000 tons. To address 
SO2 emissions originating from the combustion of residential 
heating, the state's Legislature adopted Connecticut General Statute 
Title 16a, Chapter 296, Section 16a-21a.\23\ As of July 1, 2014 the 
sulfur content for home heating oil in Connecticut is 500 parts per 
million (ppm), or 0.05% by weight. The new limit of 15 ppm or 0.0015% 
by weight, which will be federally effective on July 1, 2018, 
represents a 97% reduction in emissions compared with allowable levels.
---------------------------------------------------------------------------

    \23\ See 81 FR 35636 (June 3, 2016).
---------------------------------------------------------------------------

    According to EPA's guidance ``Air Emission Factors and 
Quantification AP 42, Compilation of Air Pollutant Emission Factors'' 
Chapter 1.3 titled, ``Fuel Oil Combustion,'' \24\ more than 95% of the 
sulfur in fuel is converted to SO2. The Census Bureau 
estimates that in 2000 approximately 52.4% of the 1.3 million 
households in Connecticut relied on fuel oil as their heating fuel, or 
681,200 households.\25\ It is not uncommon for typical households in 
northeastern states such as Connecticut to use 800 gallons of fuel oil 
per season, and prior to July 1, 2014, the sulfur content in fuel oil 
in Connecticut ranged between 2,000-3,000 ppm, approximately six times 
the current limit. EPA's emission factor to determine the approximate 
amount of SO2 per 1000 gallons of fuel oil is 142 x S, where 
S is the percent by weight of sulfur in fuel oil.\26\ At 3,000 ppm, the 
percent by weight is 0.3, and therefore the amount of SO2 
produced by the combustion of 1000 gallons of fuel oil is approximately 
42.6 pounds. This yields an approximate yearly mass amount 
SO2 emissions, as a result of fuel oil combustion, of over 
11,600 tons, which is consistent with the 2011 NEI data of 11,437 tons 
for home heating oil.
---------------------------------------------------------------------------

    \24\ https://www3.epa.gov/ttn/chief/ap42/ch01/final/c01s03.pdf.
    \25\ https://www.census.gov/hhes/www/housing/census/historic/fuels.html.
    \26\ See EPA's guidance ``Air Emission Factors and 
Quantification AP 42, Compilation of Air Pollutant Emission 
Factors,'' page 1.3-12.
---------------------------------------------------------------------------

    At the time of this proposed rulemaking, the maximum allowable 
sulfur content in fuel oil allowed by the Connecticut SIP is 0.05% by 
weight, which should yield estimated yearly SO2 emissions of 
1,900 tons from these diffuse emissions sources, which is substantially 
less than the 2011 NEI data. By 2018, the annual SO2 
emissions in Connecticut as a result of the 0.0015% maximum sulfur 
content in heating oil will be approximately 60 tons. While EPA does 
not currently have

[[Page 21362]]

a way to quantify the impacts of multiple small sources of 
SO2 (the current estimate is approximately 6 pounds of 
SO2 per year per household that uses fuel oil) in 
neighboring states, the drastic decrease in the allowable sulfur 
content in fuel oil and the associated reductions in SO2 
emissions, combined with the diffuse nature of these emissions, make it 
unlikely that the current and future emissions from residential 
combustion of fuel oil are likely to lead to an exceedance of the NAAQS 
in a neighboring state. Specifically, by 2018, the yearly 
SO2 emissions per household using fuel oil will drop to 
under 0.20 pounds per year.
    Lastly, for the purposes of ensuring that SO2 emissions 
at new or modified sources in Connecticut do not adversely impact air 
quality, the state's SIP-approved new source review (NSR) and 
prevention of significant deterioration (PSD) programs are contained in 
RCSA Section 22a-174-2a, ``Procedural Requirements for New Source 
Review and Title V Permitting'' and RCSA Section 22a-174-3a, ``Permit 
to Construct and Operate Stationary Sources.'' Both sets of regulations 
ensure that SO2 emissions due to new facility construction 
or modifications at existing facilities will not adversely impact air 
quality in Connecticut or in neighboring states.
5. Other SIP-Approved or Federally Enforceable Regulations
    In addition to the state's SIP-approved provisions that directly 
control emissions of SO2, sources in Connecticut are also 
subject to additional requirements that will have the effect of further 
limiting SO2 emissions. On September 24, 2013 (78 FR 58467), 
EPA published its final rulemaking approving Connecticut's request to 
re-designate the Connecticut portion of the New York-N. New Jersey-Long 
Island, NY-NJ-CT PM2.5 nonattainment area to attainment. The 
controls and federally enforceable measures approved into the SIP were 
for the purposes of attaining the 1997 annual and 2006 24-hour 
PM2.5 NAAQS. However, as part of state's re-designation 
request and consistent with the requirements of the CAA, Connecticut 
submitted SO2 emissions projections for Fairfield and New 
Haven Counties, showing that SO2 emissions in those counties 
are projected to decrease by more than 50% between 2007 and 2025 as a 
result of federal regulations and state regulations adopted into the 
Connecticut SIP. EPA expects similar reductions throughout the rest of 
the state following the state's adoption of a low sulfur fuel 
regulation that requires further reductions in the fuel oil sulfur 
content by July 1, 2018.\27\
---------------------------------------------------------------------------

    \27\ The reductions are due to a supplement to Connecticut's 
Regional Haze Plan. See 81 FR 33134 (May 25, 2016).
---------------------------------------------------------------------------

    In addition to the SIP-approved regulations in RCSA, EPA observes 
that facilities in Connecticut are also subject to the Federal 
requirements contained in regulations such as Mercury Air Toxic 
Standards, and the National Emission Standards for Hazardous Air 
Pollutants for Major Sources: Industrial, Commercial, and Institutional 
Boilers and Process Heaters. These regulations reduce acid gases, which 
includes reductions in SO2 emissions.
6. Conclusion
    As discussed in more detail above, EPA has considered the following 
information in evaluating the state's satisfaction of the requirements 
of prong 1 of CAA section 110(a)(2)(D)(i)(I):
    (1) EPA has not identified any current air quality problems in 
nearby areas in the adjacent states (Massachusetts, Rhode Island, and 
New York) relative to the 2010 SO2 NAAQS;
    (2) Connecticut demonstrated using air dispersion modeling, that 
its largest stationary source SO2 emitters are not expected 
to cause SO2 air quality problems in other states relative 
to the 2010 SO2 NAAQS;
    (3) Past and projected future emission trends demonstrate that such 
air quality problems in other nearby states are unlikely to occur due 
to sources in Connecticut; and
    (4) Current SIP provisions and other federal programs will further 
reduce SO2 emissions from sources within Connecticut.
    Based on the analysis provided by the state in its SIP submission 
and based on each of the factors listed above, EPA proposes to find 
that that sources or emissions activity within the state will not 
contribute significantly to nonattainment of the 2010 SO2 
NAAQS in any other state.

D. Prong 2 Analysis--Interference With Maintenance of the NAAQS

    Prong 2 of the good neighbor provision requires state plans to 
prohibit emissions that will interfere with maintenance of a NAAQS in 
another state. Given the continuing trend of decreased emissions from 
sources within Connecticut, EPA believes that reasonable criteria to 
ensure that sources or emissions activity originating within 
Connecticut do not interfere with its neighboring states' ability to 
maintain the NAAQS consists of evaluating whether these decreases in 
emissions can be maintained over time.
    Table 11 below summarizes the SO2 emissions data for the 
period of time between 2000 and 2015 for the four facilities in 
Connecticut emitting at least 100 tpy of SO2 in any given 
year between 2009 and 2011. These facilities were chosen by the state 
in its analysis and Technical Justification because they were the only 
facilities to be emitting greater than 100 tons per year of 
SO2 at the time of the state's submission.

       Table 11--Trend in SO2 Emissions in Tons per Year (tpy) for the Four Connecticut Electric Utilities
----------------------------------------------------------------------------------------------------------------
                    Facility                           2000            2005            2010            2015
----------------------------------------------------------------------------------------------------------------
Middletown Power................................           4,396           1,298             164             147
Norwalk Power *.................................           6,759           1,001             140               0
PSEG Power New Haven............................           9,256           1,445             257             154
PSEG Power BPT Harbor...........................           9,220           2,831           1,273             707
                                                 ---------------------------------------------------------------
    Total.......................................          29,631           6,574           1,833           1,265
----------------------------------------------------------------------------------------------------------------

    The data shows SO2 emissions from these four facilities 
have decreased substantially over time, with one facility, Norwalk 
Power, ceasing operations in June of 2013 and having its permit 
permanently revoked in November 2013. A number of factors are involved 
that caused this decrease in emissions, including the effective date of 
RSCA 22a-174-19a (December 28, 2000) and the change in capacity factors 
over time due to increased usage of

[[Page 21363]]

natural gas to generate electricity. The EPA believes that since actual 
SO2 emissions from the facilities currently operating in 
Connecticut have decreased between 2000 and 2015, this trend is not 
expected to interfere with the neighboring states' ability to maintain 
the 2010 SO2 NAAQS.
    EPA expects SO2 from sources other than the four 
identified electric generating units will be lower in the future. In 
2014, the state adopted lower sulfur-in-fuel limits for stationary 
sources that are not subject to RSCA 22a-174-19a. These new limits are 
codified in RSCA 22a-174-19b, which as noted above, were approved into 
the SIP in 2016 as part of Connecticut's regional haze plan. The 
sulfur-in-fuel limits contained in RSCA 22a-174-19b will limit these 
stationary sources that are not subject to RSCA 22a-174-19a to 
combusting residual fuel oil with a sulfur content of 0.3% or less by 
weight and distillate fuel oil of 0.0015% or less by weight will take 
effect on July 1, 2018.
    Significant reductions from the largest category of SO2 
emissions in Connecticut, home heating oil, will also continue into the 
future. According to the NEI, there already was a reduction of 
SO2 emissions from this source category of over 3,000 tons 
between 2011 and 2014. Further reductions will occur as the sulfur-in-
fuel limit for home heating oil was lowered to 0.05% by weight on July 
1, 2014, therefore only impacting half of the heating season in 2014, 
and an even more restrictive limit of 0.0015% by weight on July 1, 
2018.
    Lastly, any future large sources of SO2 emissions will 
be addressed by Connecticut's SIP-approved Prevention of Significant 
Deterioration (PSD) program. Future minor sources with SO2 
emissions of 15 tons but less than the PSD thresholds will be addressed 
by the state's minor new source review permit program. The permitting 
regulations contained within these programs are expected to ensure that 
ambient concentrations of SO2 in Massachusetts, New York, 
New Jersey, and Rhode Island are not exceeded as a result of new 
facility construction or modification originating in Connecticut.
    It is worth noting air quality trends for concentrations of 
SO2 in the Northeastern United States.\28\ This region has 
experienced a 77% decrease in the annual 99th percentile of daily 
maximum 1-hour averages between 2000 and 2015 based on 46 monitoring 
sites, and the most recently available data for 2015 indicates that the 
mean value at these sites was 17.4 ppb, or less than 25% of the NAAQS. 
When this trend is evaluated alongside the monitored SO2 
concentrations within the state of Connecticut as well as the 
SO2 concentrations recorded at monitors in Massachusetts, 
New York, and Rhode Island, EPA does not believe that sources or 
emissions activity from within Connecticut are significantly different 
than the overall decreasing monitored SO2 concentration 
trend in the Northeast region. As a result, EPA finds it unlikely that 
sources or emissions activity from within Connecticut will interfere 
with other states' ability to maintain the 2010 SO2 NAAQS.
---------------------------------------------------------------------------

    \28\ See https://www.epa.gov/air-trends/sulfur-dioxide-trends.
---------------------------------------------------------------------------

    Based on each of factors contained in the maintenance analysis, EPA 
proposes to find the sources or emissions activity within the state 
will not interfere with maintenance of the 2010 SO2 NAAQS in 
any other state.

IV. Proposed Aaction

    In light of the above analysis, EPA is proposing to approve 
Connecticut's infrastructure submittal for the 2010 SO2 
NAAQS as it pertains to section 110(a)(2)(D)(i)(I) of the CAA. EPA is 
soliciting public comments on the issues discussed in this notice. 
These comments will be considered before taking final action. 
Interested parties may participate in the Federal rulemaking procedure 
by submitting written comments to EPA New England Regional Office 
listed in the ADDRESSES section of this Federal Register or by 
submitting comments electronically, by mail, or through hand delivery/
courier following the directions in the ADDRESSES section of this 
Federal Register.

V. Statutory and Executive Order Reviews

    Under the Clean Air Act, the Administrator is required to approve a 
SIP submission that complies with the provisions of the Act and 
applicable Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). 
Thus, in reviewing SIP submissions, EPA's role is to approve state 
choices, provided that they meet the criteria of the Clean Air Act. 
Accordingly, this proposed action merely approves state law as meeting 
Federal requirements and does not impose additional requirements beyond 
those imposed by state law. For that reason, this proposed action:
     Is not a significant regulatory action subject to review 
by the Office of Management and Budget under Executive Orders 12866 (58 
FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the Clean Air Act; and
     Does not provide EPA with the discretionary authority to 
address, as appropriate, disproportionate human health or environmental 
effects, using practicable and legally permissible methods, under 
Executive Order 12898 (59 FR 7629, February 16, 1994).
    In addition, the SIP is not approved to apply on any Indian 
reservation land or in any other area where EPA or an Indian tribe has 
demonstrated that a tribe has jurisdiction. In those areas of Indian 
country, the rule does not have tribal implications and will not impose 
substantial direct costs on tribal governments or preempt tribal law as 
specified by Executive Order 13175 (65 FR 67249, November 9, 2000).

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Sulfur oxides.

    Dated: March 16, 2017.
Deborah A. Szaro,
Acting Regional Administrator, EPA New England.
[FR Doc. 2017-09183 Filed 5-5-17; 8:45 am]
 BILLING CODE 6560-50-P