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[Federal Register Volume 81, Number 163 (Tuesday, August 23, 2016)]
[Proposed Rules]
[Pages 57522-57531]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-20118]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R04-OAR-2015-0624; FRL-9951-27-Region 4]

Air Plan Approval; FL: Hillsborough Area; SO2 Attainment 
Demonstration

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve a State Implementation Plan (SIP) revision, submitted by the 
State of Florida through the Florida Department of Environmental 
Protection (FL DEP), to EPA on April 3, 2015, for the purpose of 
providing for attainment of the 2010 Sulfur Dioxide (SO2) 
National Ambient Air Quality Standards (NAAQS) in the Hillsborough 
County SO2 nonattainment area (hereafter referred to as the 
``Hillsborough Area'' or ``Area''). The Hillsborough Area is comprised 
of a portion of Hillsborough County in Florida surrounding the Mosaic 
Fertilizer, LLC Riverview plant (hereafter referred to as ``Mosaic''). 
The attainment plan includes the base year emissions inventory, an 
analysis of the reasonably available control technology (RACT) and 
reasonably available control measures (RACM) requirements, a reasonable 
further progress (RFP) plan, a modeling demonstration of SO2 
attainment, and contingency measures for the Hillsborough Area. As a 
part of approving the attainment demonstration, EPA is also proposing 
to approve into the Florida SIP the SO2 emissions limits and 
associated compliance parameters. This action is being taken in 
accordance with Clean Air Act (CAA or Act) and EPA's guidance related 
to SO2 attainment planning.

DATES: Comments must be received on or before September 22, 2016.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R04-
OAR-2015-0624 at http://www.regulations.gov. Follow the online 
instructions for submitting comments. Once submitted, comments cannot 
be edited or removed from Regulations.gov. EPA may publish any comment 
received to its public docket. Do not submit electronically any 
information you consider to be Confidential Business Information (CBI) 
or other information whose disclosure is restricted by statute. 
Multimedia submissions (audio, video, etc.) must be accompanied by a 
written comment. The written comment is considered the official comment 
and should include discussion of all points you wish to make. EPA will 
generally not consider comments or comment contents located outside of 
the primary submission (i.e., on the web, cloud, or other file sharing 
system). For additional submission methods, the full EPA public comment 
policy, information about CBI or multimedia submissions, and general 
guidance on making effective comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: D. Brad Akers, Air Regulatory 
Management Section, Air Planning and Implementation Branch, Air, 
Pesticides and Toxics Management Division, U.S. Environmental 
Protection Agency, Region 4, 61 Forsyth Street SW., Atlanta, Georgia 
30303-8960. Mr. Akers can be reached via electronic mail at 
akers.brad@epa.gov or via telephone at (404) 562-9089.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. What action is EPA proposing to take?
II. What is the background for EPA's proposed action?
III. What is included in Florida's attainment plan for the 
Hillsborough Area?
IV. What is EPA's analysis of Florida's attainment plan for the 
Hillsborough Area?
    A. Pollutants Addressed
    B. Emissions Inventory Requirements
    C. Air Quality Modeling
    D. RACM/RACT
    E. RFP Plan
    F. Contingency Measures
    G. Attainment Date
V. Proposed Action
VI. Statutory and Executive Order Reviews

I. What action is EPA proposing to take?

    EPA is proposing to approve Florida's SIP revision for the 
Hillsborough Area,

[[Page 57523]]

as submitted through FL DEP to EPA on April 3, 2015, for the purpose of 
demonstrating attainment of the 2010 1-hour SO2 NAAQS. 
Specifically, EPA is proposing to approve the base year emissions 
inventory, a modeling demonstration of SO2 attainment, an 
analysis of RACM/RACT, a RFP plan, and contingency measures for the 
Hillsborough Area. Additionally, EPA is proposing to approve specific 
SO2 emission limits and compliance parameters established 
for the two SO2 sources impacting the Hillsborough Area into 
the Florida SIP.
    EPA has preliminarily determined that Florida's SO2 
attainment plan for the 2010 1-hour SO2 NAAQS for 
Hillsborough County meets the applicable requirements of the CAA and 
EPA's SO2 Nonattainment Guidance.\1\ Moreover, the 
Hillsborough Area is currently showing a design value below the 2010 
SO2 NAAQS, having implemented most of the control measures 
included in the SIP submittal. Thus, EPA is proposing to approve 
Florida's attainment plan for the Hillsborough Area as submitted on 
April 3, 2015. EPA's analysis for this proposed action is discussed in 
Section IV of this proposed rulemaking.
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    \1\ EPA's April 23, 2014 memorandum entitled ``Guidance for the 
1-Hour SO2 Nonattainment Area SIP Submissions,'' 
hereafter referred to as the ``SO2 Nonattainment 
Guidance.''
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II. What is the background for EPA's proposed action?

    On June 2, 2010, the EPA Administrator signed a final rule 
establishing a new SO2 NAAQS as a 1-hour standard of 75 
parts per billion (ppb), based on a 3-year average of the annual 99th 
percentile of 1-hour daily maximum concentrations. See 75 FR 35520 
(June 22, 2010). This action also revoked the existing 1971 annual 
standard and 24-hour standards, subject to certain conditions.\2\ EPA 
established the NAAQS based on significant evidence and numerous health 
studies demonstrating that serious health effects are associated with 
short-term exposures to SO2 emissions ranging from 5 minutes 
to 24 hours with an array of adverse respiratory effects including 
narrowing of the airways which can cause difficulty breathing 
(bronchoconstriction) and increased asthma symptoms. For more 
information regarding the health impacts of SO2, please 
refer to the June 22, 2010 final rulemaking. See 75 FR 35520. Following 
promulgation of a new or revised NAAQS, EPA is required by the CAA to 
designate areas throughout the United States as attaining or not 
attaining the NAAQS; this designation process is described in section 
107(d)(1) of the CAA. On August 5, 2013, EPA promulgated initial air 
quality designations of 29 areas for the 2010 SO2 NAAQS (78 
FR 47191), which became effective on October 4, 2013, based on 
violating air quality monitoring data for calendar years 2009-2011, 
where there was sufficient data to support a nonattainment 
designation.\3\
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    \2\ EPA's June 22, 2010 final action revoked the two 1971 
primary 24-hour standard of 140 ppb and the annual standard of 30 
ppb because they were determined not to add additional public health 
protection given a 1-hour standard at 75 ppb. See 75 FR 35520. 
However, the secondary 3-hour SO2 standard was retained. 
Currently, the 24-hour and annual standards are only revoked for 
those areas the EPA has already designated for the 2010 1-hour 
SO2 NAAQS in August 2013 and June 30, 2016, including the 
Hillsborough Area. See 40 CFR 50.4(e).
    \3\ EPA is continuing its designation efforts for the 2010 
SO2 NAAQS. Pursuant to a court-ordered consent decree 
finalized March 2, 2015, in the U.S. District Court for the Northern 
District of California, EPA must complete the remaining designations 
for the rest of the country on a schedule that contains three 
specific deadlines. By July 2, 2016, EPA must designate areas 
specified in the March 2, 2015 consent decree based on specific 
emission criteria. Sierra Club, et al. v. Environmental Protection 
Agency, 13-cv-03953-SI (2015). The last two deadlines for completing 
designations, December 2017 and December 2020 are expected to be 
informed by information required pursuant the ``Data Requirements 
Rule for the 2010 1-Hour Sulfur Dioxide (SO2) Primary 
National Ambient Air Quality Standard (NAAQS); Final Rule,'' or 
``Data Requirements Rule.'' See 80 FR 51052 (August 21, 2015). 
http://www.epa.gov/airquality/sulfurdioxide/designations/pdfs/201503Schedule.pdf. On June 30, 2016, EPA designated a total of 61 
areas for the 2010 1-hour SO2 standard as part of the 2nd 
round of designations pursuant to the March 2, 2015 consent decree.
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    Effective on October 4, 2013, the Hillsborough Area was designated 
as nonattainment for the 2010 SO2 NAAQS for an area that 
encompasses the primary SO2 emitting source Mosaic 
fertilizer plant and the nearby SO2 monitor (Air Quality 
Site ID: 12-057-0109). The October 4, 2013, final designation triggered 
a requirement for Florida to submit a SIP revision with a plan for how 
the Area would attain the 2010 SO2 NAAQS as expeditiously as 
practicable, but no later than October 4, 2018, in accordance with CAA 
section 172(b).
    The required components of a nonattainment plan submittal are 
listed in section 172(c) of part D of the CAA. The base year emissions 
inventory (section 172(c)(3)) is required to show a ``comprehensive, 
accurate, current inventory'' of all relevant pollutants in the 
nonattainment area. The nonattainment plan must identify and quantify 
any expected emissions from the construction of new sources to account 
for emissions in the area that might affect RFP toward attainment, or 
with attainment and maintenance of the NAAQS, and provide for a 
nonattainment new source review (NNSR) program (section 172(c)(5)). The 
attainment demonstration must include a modeling analysis showing that 
the enforceable emissions limitations and other control measures taken 
by the state will provide for expeditious attainment of the NAAQS 
(section 172(c)). The nonattainment plan must include an analysis of 
the RACM considered, including RACT (section 172(c)(1)). RFP for the 
nonattainment area must be addressed in the submittal. Finally, the 
nonattainment plan must provide for contingency measures (section 
172(c)(9)) to be implemented in the case that RFP toward attainment is 
not made, or the area fails to attain the NAAQS by the attainment date.

III. What is included in Florida's attainment plan for the Hillsborough 
Area?

    In accordance with section 172(c) of the CAA, the Florida 
attainment plan for the Hillsborough Area includes: (1) An emissions 
inventory for SO2 for the plan's base year (2011); and (2) 
an attainment demonstration. The attainment demonstration includes: 
Technical analyses that locate, identify, and quantify sources of 
emissions contributing to violations of the 2010 SO2 NAAQS; 
a declaration that FL DEP is unaware of any future growth in the area 
that would be subject to CAA 173,\4\ and the assertion that the NNSR 
program approved in the SIP at Section 62-252.500, Florida 
Administrative Code (F.A.C.) would account for any such growth; a 
modeling analysis of an emissions control strategy for the primary 
SO2 source, Mosaic, and a nearby source, the Tampa Electric 
Company's (TECO's) Big Bend electric generating facility (hereafter 
referred to

[[Page 57524]]

as ``TECO''), that attains the SO2 NAAQS by the October 4, 
2018 attainment date; a determination that the control strategy for the 
primary SO2 source within the nonattainment areas 
constitutes RACM/RACT; adherence to a construction schedule to ensure 
emissions reductions are achieved as expeditiously as practicable; a 
request from FL DEP that emissions reduction measures including system 
upgrades and/or emissions limitations with schedules for implementation 
and compliance parameters be incorporated into the SIP; and contingency 
measures.
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    \4\ The CAA new source review (NSR) program is composed of three 
separate programs: Prevention of significant deterioration (PSD), 
NNSR, and Minor NSR. PSD is established in part C of title I of the 
CAA and applies in areas that meet the NAAQS--``attainment areas''--
as well as areas where there is insufficient information to 
determine if the area meets the NAAQS--``unclassifiable areas.'' The 
NNSR program is established in part D of title I of the CAA and 
applies in areas that are not in attainment of the NAAQS--
``nonattainment areas.'' The Minor NSR program addresses 
construction or modification activities that do not qualify as 
``major'' and applies regardless of the designation of the area in 
which a source is located. Together, these programs are referred to 
as the NSR programs. Section 173 of the CAA lays out the NNSR 
program for preconstruction review of new major sources or major 
modifications to existing sources, as required by CAA section 
172(c)(5). The programmatic elements for NNSR include, among other 
things, compliance with the lowest achievable emissions rate and the 
requirement to obtain emissions offsets.
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IV. What is EPA's analysis of Florida's attainment plan for the 
Hillsborough Area?

    Consistent with CAA requirements (see, section 172), an attainment 
demonstration for a SO2 nonattainment area must include a 
showing that the area will attain the 2010 SO2 NAAQS as 
expeditiously as practicable. The demonstration must also meet the 
requirements of 40 Code of Federal Regulations (CFR) 51.112 and Part 
51, Appendix W, and include inventory data, modeling results, and 
emissions reduction analyses on which the state has based its projected 
attainment. In the case of the Hillsborough Area, 2013-2015 quality-
assured and certified air quality data indicated a design value below 
the 2010 1-hour SO2 NAAQS. EPA is proposing that the 
attainment plan submitted by Florida is sufficient, and EPA is 
proposing to approve the plan to assure ongoing attainment.

A. Pollutants Addressed

    Florida's SO2 attainment plan evaluates SO2 
emissions for the area within the portion of Hillsborough County that 
is designated nonattainment for the 2010 SO2 NAAQS. There 
are no significant precursors to consider for the SO2 
attainment plan. SO2 is a pollutant that arises from direct 
emissions, and therefore concentrations are highest relatively close to 
the source(s) and much lower at greater distances due to dispersion. 
See SO2 Nonattainment Guidance. Thus, SO2 
concentration patterns resemble those of other directly emitted 
pollutants like lead and differ from those of photochemically-formed 
(secondary) pollutants such as ozone. The two sources included in FL 
DEP's SIP to address the Hillsborough Area and their operations are 
briefly described later on in this preamble. As the Hillsborough Area 
includes one such major point source of SO2 and one source 
just outside the Area, it is expected that an attainment demonstration 
addressing SO2 emissions at these two sources will 
effectively ensure that the Area will attain by the attainment date of 
October 4, 2018.

B. Emissions Inventory Requirements

    States are required under section 172(c)(3) of the CAA to develop 
comprehensive, accurate and current emissions inventories of all 
sources of the relevant pollutant or pollutants in the area. These 
inventories provide a detailed accounting of all emissions and emission 
sources by precursor or pollutant. In addition, inventories are used in 
air quality modeling to demonstrate that attainment of the NAAQS is as 
expeditious as practicable. The April 23, 2014, SO2 
Nonattainment Guidance provides that the emissions inventory should be 
consistent with the Air Emissions Reporting Requirements (AERR) at 
Subpart A to 40 CFR part 51.\5\
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    \5\ The AERR at Subpart A to 40 CFR part 51 cover overarching 
federal reporting requirements for the states to submit emissions 
inventories for criteria pollutants to EPA's Emissions Inventory 
System. The EPA uses these submittals, along with other data 
sources, to build the National Emissions Inventory.
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    For the base year inventory of actual emissions, a ``comprehensive, 
accurate and current,'' inventory can be represented by a year that 
contributed to the three-year design value used for the original 
nonattainment designation. The final SO2 Nonattainment 
Guidance notes that the base year inventory should include all sources 
of SO2 in the nonattainment area as well as any sources 
located outside the nonattainment area which may affect attainment in 
the area. Florida elected to use 2011 as the base year. Actual 
emissions from all sources of SO2 in the Hillsborough Area 
were reviewed and compiled for the base year emissions inventory 
requirement. All stationary sources of SO2 emissions located 
in the Hillsborough Area were estimated and included in the inventory, 
and a source outside the Area that FL DEP determined caused or 
contributed to elevated SO2 concentrations within the 
nonattainment area was also included.
    The primary SO2-emitting point source located within the 
Hillsborough Area is the Mosaic fertilizer plant, which produces acids 
and fertilizers including sulfuric acid, phosphoric acid, ammonium 
sulfate, diammonium phosphate, and monoammonium phosphate. Mosaic 
consists of three main SO2 emitters and six smaller 
emitters:
     Emissions Unit (EU) 004 (Mosaic EU 004) is the No. 7 
sulfuric acid plant, which burns sulfur and oxygen to form 
SO2, then catalytically converts the SO2 to 
SO3, finally absorbing the SO3 into sulfuric 
acid, and has a design capacity of 3,200 tons per day (tpd) of 100 
percent sulfuric acid;
     Mosaic EU 005 is the No. 8 sulfuric acid plant, which 
operates similar to Mosaic EU 004 and has a design capacity of 2,700 
tpd of 100 percent sulfuric acid;
     Mosaic EU 006 is the No. 9 sulfuric acid plant, which 
operates similar to Mosaic EU 004 and has a design capacity of 3,400 
tpd of 100 percent sulfuric acid; and
     Mosaic EUs 007, 043, 055, 066, 067, and 068 provide 
various services to other parts of the facility and combine for less 
than 1 ton per year (tpy); for more information on these miscellaneous 
units, see the April 3, 2015, submittal.

The emissions at all units for the Mosaic facility were recorded using 
data collected from continuous emissions monitoring systems (CEMS) and 
are quality-assured by FL DEP.
    The next largest SO2 source within the nonattainment 
area is the Ajax Paving Industries, Inc., Plant No. 6 (Ajax), which 
produces asphalt and recycles reclaimed asphalt. SO2 
emissions from Ajax were 5.91 tons in 2011. Ajax asphalt plant consists 
of two main SO2 emitters:
     Ajax EU 005 is a diesel engine and power generator for a 
crusher; and
     Ajax EU 006 is the drum mix asphalt plant.
    The final SO2 source within the nonattainment area is 
Harsco Minerals (Harsco), which recycles minerals and byproducts from 
steel production. SO2 emissions from Harsco were 0.003 tons 
in 2011. Harsco consists of one SO2 emitter:
     Harsco EU001 is a rotary slag dryer.
    The largest SO2 source within 25 kilometers (km) outside 
the Hillsborough Area is TECO, which is an electric generating 
facility. The TECO facility consists of four main SO2 
emitters and four smaller SO2 emitters:
     TECO EUs 001, 002, 003, and 004 are fossil fuel fired 
steam generators that fire coal or a coal-and-petroleum coke mixture 
with no more than 20 percent petroleum coke by weight, or coal blended 
with residual coal from the Polk Power Station and on-site generated 
fly ash, and which are rated at 445 MW electrical production for EUs 
001-003, and 486 MW for EU 004;
     TECO EUs 041, 042, 043, 044, provide energy via simple 
cycle combustion and diesel generators and combine for less than 1 tpy; 
for more information on these miscellaneous units, see the April 3, 
2015, submittal.
    Emissions from the TECO facility were collected via CEMS or 
calculated.

[[Page 57525]]

Specifically, TECO EUs 001--004, the only significant SO2 
emitters at the facility, are equipped with CEMS, while the remaining 
units were estimated based on fuel use and actual hour of operation.
    Pursuant to Florida's SIP-approved regulations at Chapter 62-
210.370, F.A.C., paragraph (3), FL DEP collects annual operating 
reports (AORs), incorporated by reference into the SIP at 62-
210.900(5), from all major sources. These AORs were used to develop the 
base year inventory for actual emissions for the point sources and 
satisfy the AERR. FL DEP utilized EPA's 2011 National Emissions 
Inventory (NEI), Version 2 to obtain estimates of the area and nonroad 
sources. For onroad mobile source emissions, FL DEP utilized EPA's 
Motor Vehicle Emissions Simulator (MOVES2014). A more detailed 
discussion of the emissions inventory development for the Hillsborough 
Area can be found in Florida's April 3, 2015, submittal.

    Table 1 shows the level of emissions, expressed in tpy, in the 
Hillsborough Area for the 2011 base year by emissions source category. 
The point source category includes all sources within the nonattainment 
area as well as TECO, which is located outside the Hillsborough Area, 
but determined by FL DEP to contribute to nonattainment.

                                          Table 1--2011 Base Year Emissions Inventory for the Hillsborough Area
                                                                          [tpy]
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                                Year                                      Point            Onroad          Nonroad            Area            Total
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2011...............................................................       12,145.90             1.96             8.88             2.63        12,159.37
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    EPA has evaluated Florida's 2011 base year emissions inventory for 
the Hillsborough Area and has made the preliminary determination that 
this inventory was developed consistent with EPA's guidance. Therefore, 
pursuant to section 172(c)(3), EPA is proposing to approve Florida's 
2011 base year emissions inventory for the Hillsborough Area.
    The attainment demonstration also provides for a projected 
attainment year inventory that includes estimated emissions for all 
emission sources of SO2 which are determined to impact the 
nonattainment area for the year in which the area is expected to attain 
the standard. This inventory must address any future growth in the 
Area. Growth means any potential increases in emissions of the 
pollutant for which the Hillsborough Area is nonattainment 
(SO2) due to the construction and operation of new major 
sources, major modifications to existing sources, or increased minor 
source activity. FL DEP included a statement in its April 3, 2015, 
submittal declaring that FL DEP is unaware of any plans for the growth 
of major sources in the Hillsborough Area, and that normal minor source 
growth should not significantly impact the Area. FL DEP further asserts 
that the NNSR program at Section 62-252.500, F.A.C., approved into the 
SIP and last updated on June 27, 2008 (see 73 FR 36435), would address 
any proposed new major sources or planned major modifications for 
SO2 sources. The NNSR program includes lowest achievable 
emissions rate, offsets, and public hearing requirements.
    FL DEP provided a 2018 projected emissions inventory for all known 
sources included in the 2011 base year inventory, discussed previously, 
that were determined to impact the Hillsborough County nonattainment 
area. The projected 2018 emissions in Table 2 are estimated actual 
emissions, representing a 49 percent reduction from the base year 
SO2 emissions. The point source emissions were estimated by 
multiplying the 2018 allowable emissions by the ratio of 2011 actual 
emissions to allowable emissions. Per the SO2 Nonattainment 
Guidance, the allowable emissions limits that FL DEP is requesting EPA 
approve into the SIP as a control measure were modeled to show 
attainment. These allowable emission limits are higher than the 
projected actual emissions included in the future year inventory, and 
therefore offer greater level of certainty that the NAAQS will be 
protected under all operating scenarios. Emissions estimates for onroad 
sources were re-estimated with MOVES2014. The nonroad and area source 
emissions were scaled based on estimated population growth in the 
Hillsborough Area portion of Hillsborough County.

                    Table 2--Projected 2018 SO2 Emissions Inventory for the Hillsborough Area
                                                      [tpy]
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              Year                     Point          Onroad          Nonroad          Area            Total
----------------------------------------------------------------------------------------------------------------
2011............................       12,145.90            1.96            8.88            2.63       12,159.37
2018............................        6,211.08            0.75            9.75            2.89        6,224.47
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C. Air Quality Modeling

    The SO2 attainment demonstration provides an air quality 
dispersion modeling analysis to demonstrate that control strategies 
chosen to reduce SO2 source emissions will bring the area 
into attainment by the statutory attainment date of October 4, 2018. 
The modeling analysis, outlined in Appendix W to 40 CFR part 51 (EPA's 
Modeling Guidance),\6\ is used for the attainment demonstration to 
assess the control strategy for a nonattainment area and establish 
emission limits that will provide for attainment. The analysis requires 
five years of meteorological data to simulate the dispersion of 
pollutant plumes from multiple point, area, or volume sources across 
the averaging times of interest. The modeling demonstration typically 
also relies on maximum allowable emissions from sources in the 
nonattainment area. Though the actual emissions are likely to be below 
the allowable emissions, sources have the ability to run at higher 
production rates or optimize controls such that emissions approach the 
allowable emissions limits. A modeling

[[Page 57526]]

analysis that provides for attainment under all scenarios of operation 
for each source must therefore consider the worst case scenario of both 
the meteorology (e.g., predominant wind directions, stagnation, etc.) 
and the maximum allowable emissions.
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    \6\ 40 CFR part 51 Appendix W (EPA's Guideline on Air Quality 
Models) (November 2005) located at http://www3.epa.gov/ttn/scram/guidance/guide/appw_05.pdf. EPA has proposed changes to Appendix W. 
See 80 FR 45340 (July 29, 2015).
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    FL DEP's modeling analysis was developed in accordance with EPA's 
Modeling Guidance and the SO2 Nonattainment Guidance, and 
was prepared using EPA's preferred dispersion modeling system, the 
American Meteorological Society/Environmental Protection Agency 
Regulatory Model (AERMOD) consisting of the AERMOD (version 14134) 
model and two data input preprocessors AERMET (version 14134) and 
AERMAP (version 11103). AERMINUTE meteorological preprocessor and 
AERSURFACE surface characteristics preprocessor were also used to 
develop inputs to AERMET. The Building Profile Input Program for Plume 
Rise Model Enhancements (BPIP-PRIME) was also used in the downwash-
modeling. More detailed information on the AERMOD Modeling system, and 
other modeling tools and documents can be found on the EPA Technology 
Transfer Network Support Center for Regulatory Atmospheric Modeling 
(SCRAM) (http://www3.epa.gov/ttn/scram/) and in Florida's April 3, 2015 
SIP submittal in the docket for this proposed action (EPA-R04-OAR-2015-
0624) on www.regulations.gov. A brief description of the modeling used 
to support Florida's attainment demonstration is provided later on in 
this preamble.
1. Modeling Approach
    The following is an overview of the air quality modeling approach 
used to demonstrate compliance with the 2010 SO2 NAAQS, as 
submitted in Florida's April 3, 2015, submittal. The basic procedures 
are outlined later on.
    i. FL DEP developed model inputs using the AERMOD modeling system 
and processors.
    The pre-processors AERMET and AERMINUTE were used to process five 
years (i.e., 2008-2012) of 1-minute meteorological data from the Tampa 
National Weather Service Office (NWS) at the Tampa International 
Airport, Tampa, Florida, surface level site, based on FL DEP's land use 
classifications, in combination with twice daily upper-air 
meteorological information from the same site. The Tampa International 
Airport is located approximately 20 km northwest from the Hillsborough 
Area. The AERMOD pre-processor AERMAP was used to generate terrain 
inputs for the receptors, based on a digital elevation mapping database 
from the National Elevation Dataset developed by the U.S. Geological 
Survey. FL DEP used AERSURFACE to generate direction-specific land-use 
surface characteristics for the modeling. The BPIP-PRIME preprocessor 
was used to generate direction-specific building downwash parameters. 
FL DEP developed a Cartesian receptor grid across the nonattainment 
boundary (extending up to 8.5 km away from the violating monitor), with 
100 meter spacing in ambient air to ensure maximum concentrations are 
captured in the analysis. All other input options were also developed 
commensurate with the Modeling Guidance.
    Next, FL DEP selected a background SO2 concentration 
based on local SO2 monitoring data from monitoring station 
No. 12-057-0109 for the period January 2012 to December 2013. This 
background concentration from the nearby ambient air monitor is used to 
account for SO2 impacts from all sources that are not 
specifically included in the AERMOD modeling analysis. The data was 
obtained from the Florida Air Monitoring and Assessment System. This 
monitor is approximately 1.0 km to the southeast of Mosaic and 6.5 km 
north of TECO. This monitor is also the nonattainment monitor. Due to 
its close proximity to the Mosaic and TECO facilities, monitored 
concentrations at this station are strongly influenced by emissions 
from both facilities. As a result, the data was filtered to remove 
measurements where the wind direction could transport pollutants from 
Mosaic and TECO to the station. More specifically, the data was 
filtered to remove measurements where hourly wind direction was between 
275[deg] to 4[deg] or 153[deg] to 241[deg].
    ii. FL DEP performed current and post-control dispersion modeling 
using the EPA-approved AERMOD modeling system.
    iii. Finally, FL DEP derived the 99th percentile maximum 1-hour 
daily SO2 design value across the five year meteorological 
data period.
    EPA's SO2 nonattainment implementation guidance provides 
a procedure for establishing longer-term averaging times for 
SO2 emission limits (up to a 30-day rolling averaging 
time).\7\ In conjunction with states' CAA obligation to submit SIPs 
that demonstrate attainment, EPA believes that air agencies that 
consider longer term average times for a SIP emission limit should 
provide additional justification for the application of such limits. 
This justification involves determining the ``critical emission value'' 
\8\ or the 1-hour emission limit that modeling found to provide for 
attainment and adjusting this rate downward to obtain a comparable 
stringency to the modeled 1-hour average emission limit. A comparison 
of the 1-hour limit and the proposed longer term limit, in particular 
an assessment of whether the longer term average limit may be 
considered to be of comparable stringency to a 1-hour limit at the 
critical emission value, is critical for demonstrating that any longer 
term average limits in the SIP will help provide adequate assurance 
that the plan will provide for attainment and maintenance of the 1-hour 
NAAQS. This allows states to develop control strategies that account 
for variability in 1-hour emissions rates through emission limits with 
averaging times that are longer than 1 hour, using averaging times as 
long as 30 days, and still demonstrate attainment of the 2010 
SO2 NAAQS.
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    \7\ FL DEP is following the SO2 Nonattainment 
Guidance on procedures for establishing emissions limits with 
averaging periods longer than 1 hour.
    \8\ The hourly emission rate that the model predicts would 
result in the 5-year average of the annual 99th percentile of daily 
maximum hourly SO2 concentrations at the level of the 
NAAQS.
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    EPA's recommended procedure for determining longer term averaging 
times, including calculating the adjustment factor between the 1-hour 
critical emission value and the equivalent 30-day rolling average 
emissions limit, are provided in Appendices B and C of the 
SO2 Nonattainment Guidance. EPA is proposing to conclude 
that FL DEP completed this analysis for both Mosaic and TECO facilities 
to derive a SIP emission limit with a block 24-hour longer-term 
averaging time and a rolling 30-day longer-term averaging time, 
respectively, that are comparatively stringent to the 1-hour limit. For 
more details, see Florida's April 3, 2015, SIP submittal and 
accompanying appendices.
2. Modeling Results
    The SO2 NAAQS compliance results of the attainment 
modeling are summarized in Table 3. Table 3 presents the results from 
six sets of AERMOD modeling runs that were performed. The six modeling 
runs were the result of using an uncontrolled, or pre-modification, run 
and five different controlled, or post-modification, scenarios to 
account for the proposed control strategy that involves a two-unit and 
three-unit emissions cap at Mosaic, in addition to individual emissions

[[Page 57527]]

caps. Maximum allowable permitted emissions limits were used for the 
Hillsborough Area modeling demonstration. These emissions limits and 
other control measures were established in construction permits issued 
by FL DEP, to be incorporated in title V operating permits upon 
renewal. FL DEP is requesting that these emissions limits and operating 
conditions, detailed in Section IV.D. of this proposed rulemaking, be 
adopted into the SIP to become federally enforceable upon approval of 
the nonattainment plan, prior to the renewal of the title V operating 
permits for both the Mosaic and TECO facilities. The five post-control 
runs help to identify the worst possible scenario of emissions 
distributions between the three units EUs 004-006, the sulfuric acid 
plants at the Mosaic facility. Under one modeling scenario, an 
emissions cap of 600 pounds per hour (lb/hr) SO2 for Mosaic 
EUs 004-006 is evaluated based on the highest possible impact based on 
catalyst limitations and maximum sulfuric acid production. This overall 
cap was then scaled as a 24-hour limit, maintaining comparative 
stringency with the 1-hour limit (577.8 lb/hr). FL DEP rounded down the 
limit for an additional buffer from the maximum impact, resulting in a 
24-hour limit of 575 lb/hr, which compares to a 1-hour limit of 597 lb/
hr. This three-unit emissions cap was then modeled in several 
configurations to mimic variability in emissions possible under this 
scenario, apportioning emissions based on each unit emitting at their 
current individual emissions limit with the remainder of the cap 
distributed to the other units based on their relative production 
capacities. The highest impact is presented as the three-unit emissions 
cap scenario. FL DEP also evaluated a two-unit emissions caps, assuming 
at any time that two units are operating. The six possible two-unit 
operating scenarios were evaluated by each unit operating at its 
current individual emission limit, while the remainder of the 597 lb/hr 
limit is distributed to the one remaining operating unit. Again, the 
highest possible impact is presented as the two-unit operating 
scenario. For the three remaining scenarios, each sulfuric acid plant 
is assumed to operate alone at its individual emissions cap.
    The modeling utilized five years (2008-2012) of meteorological data 
from the NWS site in Tampa, Florida, as processed through AERMET, 
AERMINTE and AERSURFACE. This procedure was used since this site 
represented the nearest site with complete data.
    Table 3 shows that the maximum 1-hour average across all five years 
of meteorological data (2008-2012) is less than or equal to the 2010 
SO2 NAAQS of 75 ppb for the five post-control AERMOD 
modeling runs. For more details, see Florida's April 3, 2015 SIP 
submittal.

                             Table 3--Maximum Modeled SO2 Impacts in the Hillsborough Area, Micrograms per Cubic Meter (ppb)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                 Maximum predicted impact
          Model scenario                Averaging time    --------------------------------------     Background           Total            SO2 NAAQS
                                                                 Mosaic              TECO
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pre-modification..................  1-hour...............     425.50 (162.4)        0.82 (0.31)        20.40 (7.8)     446.72 (170.5)
Three-unit........................  1-hour...............      118.90 (45.4)       55.90 (21.3)        21.44 (8.2)      196.24 (74.9)
Two-unit..........................  1-hour...............      123.59 (47.2)       52.22 (19.9)        18.83 (7.2)      194.65 (74.3)         196.4 (75)
EU 004 only.......................  1-hour...............        0.33 (0.12)      170.84 (65.2)        17.26 (6.6)      188.43 (71.9)
EU 005 only.......................  1-hour...............        0.25 (0.10)      170.84 (65.2)        17.26 (6.6)      188.35 (71.9)
EU 006 only.......................  1-hour...............        0.33 (0.12)      170.84 (65.2)        17.26 (6.6)      188.43 (71.9)
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The pre-control analysis resulted in a predicted impact of 170.5 
ppb. The post-control analysis resulted in a worst-case predicted 
impact of 74.9 ppb. EPA is preliminarily determining that this data 
indicates sufficient reductions in air quality impact with the future 
implementation of the post-construction control plan for the Mosaic and 
TECO facilities. Furthermore, EPA is preliminarily concluding that this 
data also supports FL DEP's analysis that the controls for Mosaic 
represent RACM and RACT for the SIP. The control strategy for Mosaic, 
as reflected in its construction Air Permit No. 0570008-080-AC, 
includes eliminating fuel oil except during periods of natural gas 
curtailment or disruption; changing the catalyst used to convert 
SO2 to SO3 for improved performance; increasing 
stack heights for all three sulfuric acid plants from 150 feet (ft) to 
at least 213.25 ft; and restricting the collective SO2 
emissions to 550 lb/hr under two-unit operating scenarios, and 575 lb/
hr under three-unit operating scenarios. The result of increasing a 
stack height is that the plume has a better opportunity for greater 
dispersion across an area, minimizing stagnation and local impacts from 
higher concentrations, primarily due to the avoidance of building 
downwash effects.\9\ Mosaic's allowable SO2 emissions (total 
from all three controlled units) will be reduced from 1,140 lb/hr 
(based on total individual unit emission limits) to a maximum of 575 
lb/hr, representing at least a 49 percent allowable emissions decrease. 
The State will issue a revised title V permit to incorporate the Mosaic 
construction permit, and meanwhile is proposing the stack height 
increases and emission limits and operating scenarios related to those 
various limits be adopted into the SIP for immediate effectiveness 
authorizing Mosaic to operate in accordance with those conditions.
---------------------------------------------------------------------------

    \9\ See EPA's June 1985 guidance document, ``Guideline for 
Determination of Good Engineering Practice Stack Height (Technical 
Support Document For the Stack Height Regulations),'' which can be 
found at: http://www3.epa.gov/scram001/guidance/guide/gep.pdf.
---------------------------------------------------------------------------

    The control strategy for TECO, as reflected in its construction Air 
Permit No. 0570039-074-AC, includes the following operational changes 
to the four largest SO2-emitting units: Switching fuel oil 
to natural gas during startup, shutdown and flame stabilization at all 
four fossil fuel fired steam generators; and a combined emission limit 
from all four units of 3,162 lb/hr, to become effective no later than 
June 1, 2016. Florida will incorporate the operational change for TECO 
into its title V permit upon renewal. TECO's new combined allowable 
SO2 emissions from TECO EUs 001-004 will be reduced from 
6587.6 lb/hr (based on total individual unit emission limits) \10\ to 
3,162 lb/hr representing a 52 percent allowable emissions decrease. The 
modeling results included in Table 3 prove that TECO should be included 
in the considerations of controls because with several post-control 
modeling scenarios, TECO would contribute to over 90

[[Page 57528]]

percent of the total impact to the Hillsborough Area, and in the worst 
possible post-control modeling scenario, 28 percent of the total 
predicted impact on the Hillsborough Area would stem from TECO. 
Therefore, if no controls were implemented at TECO, the Area would not 
likely attain and maintain the 2010 SO2 NAAQS. The 
collective emission limit and related compliance parameters have been 
proposed for incorporation into the SIP to make these changes federally 
enforceable. More details on the pre- and post-construction operations 
at the facilities are included in Florida's SIP submission. FL DEP 
asserts that the proposed control strategy significantly lowers the 
modeled SO2 impacts from the TECO facility and is sufficient 
for the Hillsborough Area to attain 2010 SO2 NAAQS.
---------------------------------------------------------------------------

    \10\ The individual emission limits were included in the April 
3, 2015, submittal.
---------------------------------------------------------------------------

    EPA has reviewed the modeling that Florida submitted to support the 
attainment demonstration for the Hillsborough Area and has 
preliminarily determined that this modeling is consistent with CAA 
requirements, Appendix W and EPA's guidance for SO2 
attainment demonstration modeling.

D. RACM/RACT

    CAA section 172(c)(1) requires that each attainment plan provide 
for the implementation of all reasonably available control measures as 
expeditiously as practicable and attainment of the NAAQS. EPA 
interprets RACM, including RACT, under section 172, as measures that a 
state determines to be both reasonably available and contribute to 
attainment as expeditiously as practicable ``for existing sources in 
the area.''
    Florida's analysis is found in Section 3 of the FL DEP attainment 
demonstration within the April 3, 2015, SIP submittal. The State 
determined that controls for SO2 emissions at Mosaic are 
appropriate in the Hillsborough Area for purposes of attaining the 2010 
SO2 NAAQS. CAA section 172(c)(1) says that the plan shall 
provide for RACM, including RACT for ``existing sources in the area.'' 
Accordingly, Florida only completed a RACM/RACT analysis for Mosaic, 
since it is the only significant point source within the boundaries of 
the nonattainment area. The Ajax and Harsco sources resulted in less 
than 6 tpy between them. FL DEP included TECO in its attainment and 
impact modeling because of the source's proximity to the Hillsborough 
Area (within 5 km) and its likelihood of contributing to violations of 
the SO2 NAAQS within the area. In a modeling-based 
attainment demonstration, the means of considering impacts of sources 
outside the nonattainment area would depend on whether the sources 
cause significant concentration gradients. Florida proposed a control 
strategy for the TECO facility, but does not assert that those controls 
constitute ``the lowest emission limitation that a particular source is 
capable of meeting by the application of control technology that is 
reasonably available considering technological and economic 
feasibility'' \11\ because section 172(c)(1) provides for the 
implementation of RACT for existing sources in the area. However, an 
analysis of attainment needs to consider all potential sources, both 
inside and outside the nonattainment area that could reasonably cause 
or contribute to violations of the NAAQS within the area. FL DEP 
affirms the implementation of controls at TECO significantly lowers the 
modeled SO2 impact from the facility and is sufficient to 
attain 2010 SO2 NAAQS in the Hillsborough Area. The control 
measures at both sources are summarized later on in this preamble.
---------------------------------------------------------------------------

    \11\ Strelow, Roger. ``Guidance for Determining the 
Acceptability of SIP Regulations in Non-Attainment Areas.'' Memo to 
Regional Administrators. Office of Air and Waste Management, 
Environmental Protection Agency. Washington, DC December 9, 1976. 
Located at: http://www.epa.gov/ttn/naaqs/aqmguide/collection/cp2/19761209_strelow_ract.pdf.
---------------------------------------------------------------------------

    On January 15, 2015, FL DEP issued construction Air Permit No. 
0570008-080-AC to Mosaic for additional proposed control measures to 
reduce SO2 emissions. The specified limits and conditions 
from this construction permit, which will be adopted into the title V 
operating permit upon renewal, reflecting RACT controls, are included 
in the April 3, 2015, SIP submittal for incorporation into the SIP. The 
title V permit renewal is currently under review at the State, and is 
expected to be final by the end of calendar year 2016. The 
SO2 Nonattainment Guidance discusses an anticipated control 
compliance date of January 1, 2017. Areas that implement attainment 
plan control strategies by this date are expected to be able to show a 
year of quality-assured air monitoring data showing attainment of the 
NAAQS and a year of compliance information, which when modeled, would 
also show attainment of the NAAQS. In accordance with the schedule in 
the construction permit, Mosaic is required to implement emissions 
limits by December 15, 2016, complete final increased stack height 
construction and catalyst changes by November 2017, and the elimination 
of fuel oil by January 1, 2018. This date, though later than the date 
suggested in the SO2 Nonattainment Guidance, provides for 9 
months of compliance information by the October 4, 2018 attainment 
date, including a semiannual compliance report in July 2018. Finally, 
the Hillsborough Area is currently showing an attaining design value 
for 2013-2015, which means that attainment of the NAAQS is as 
expeditious as practicable. FL DEP included in its SIP the required 
RACT controls listed in the permit and summarized in Table 4:

            Table 4--Summary of RACT Controls for Mosaic\12\
------------------------------------------------------------------------
         Description of measure                    Explanation
------------------------------------------------------------------------
Mosaic EUs 004-006: The sulfuric acid    Mosaic was authorized to
 plants undergo construction and          construct at current stacks
 operational changes to: Increase stack   for each sulfuric acid plant,
 heights; change catalysts for sulfuric   increasing the stack height
 acid production; and meet two-unit and   from the existing level of 150
 three-unit enforceable emission limits.  ft to at least 213.25 ft.
                                         Mosaic was authorized to change
                                          catalysts and system
                                          augmentation to ensure
                                          compliance with new emission
                                          limits.
                                         Mosaic has new emission
                                          limitations, lowering the
                                          allowable SO2 from all three
                                          sulfuric acid plants
                                          collectively from 1140 lb/hr
                                          to a maximum of 575 lb/hr as a
                                          block 24-hour average.\13\
                                          These emission limits cover
                                          various operating scenarios,
                                          including individual unit
                                          emissions limits, which remain
                                          unchanged from the current
                                          permit, along with two-unit
                                          and three-unit total limits.
                                          All emission limits will be
                                          incorporated into the title V
                                          operating permit upon renewal
                                          and are proposed for
                                          incorporation into the SIP.

[[Page 57529]]

 
Plantwide: Mosaic is required to         By January 1, 2018, Mosaic will
 eliminate fuel oil use.                  not be authorized to use fuel
                                          oil, except during periods of
                                          natural gas curtailment or
                                          disruption. This condition is
                                          included in the construction
                                          permit.
------------------------------------------------------------------------

    On February 26, 2015, construction Air Permit No. 0570039-074-AC 
was issued to TECO for additional proposed control measures to reduce 
SO2 emissions. The specified limits and conditions from this 
construction permit are to be adopted into the title V operating permit 
upon renewal, and are intended to supplement the RACT adopted for 
Mosaic in the Hillsborough Area to help with attainment and maintenance 
of the 2010 SO2 NAAQS. These controls are included in the 
April 3, 2015, SIP submittal for incorporation into the SIP. TECO is 
required to implement the controls on or before June 1, 2016. The 
construction is complete and the emission limit is currently in effect. 
The title V permit renewal is under review at the State currently, and 
is expected to be final by the end of calendar year 2016. Therefore, 
the additional control strategy for TECO is in effect. The supplemental 
control measures at TECO are summarized in Table 4:
---------------------------------------------------------------------------

    \12\ The information was pulled from the April 3, 2015 
submittal, in which the original construction permit is included. 
None of these changes authorize an increased production rate at the 
facility.
    \13\ See previous discussion on longer-term emission limits. For 
more information, see the April 3, 2015 submittal.

       Table 4--Summary of Supplemental Control Measures for TECO
------------------------------------------------------------------------
         Description of measure                    Explanation
------------------------------------------------------------------------
TECO EUs 001-004 \14\: The fossil fuel   By June 1, 2016, TECO will
 fired steam generators undergo an        comply with a 3,162 lb/hr SO2
 operational change to meet a             emission limitation as a 30-
 collective enforceable emission limit.   day rolling average. This
                                          collective limit, or cap, will
                                          be incorporated into the title
                                          V operating permit upon
                                          scheduled renewal and is
                                          proposed for incorporation
                                          into the SIP.
------------------------------------------------------------------------

    EPA is proposing to approve Florida's determination that the 
proposed controls for SO2 emissions at Mosaic constitute 
RACM/RACT for that source in the Hillsborough Area based on the 
analysis described previously. Additionally, EPA proposes to approve 
Florida's determination that the supplemental control measures 
initiated at TECO help to bring the area into attainment of the 2010 
SO2 NAAQS as expeditiously as practicable. Further, EPA 
determines that no further controls would be required at Mosaic, and 
that the proposed controls are sufficient for RACM/RACT purposes for 
the Hillsborough Area at this time. EPA, therefore, proposes to approve 
Florida's April 3, 2015, SIP submission as meeting the RACM/RACT 
requirements of the CAA.
---------------------------------------------------------------------------

    \14\ Additional controls not requested for incorporation into 
the SIP for TECO EUs 001-004 include the elimination of fuel oil 
usage as of 180 days prior to June 1, 2016.
---------------------------------------------------------------------------

    Based on FL DEPs modeling demonstration, the Hillsborough Area is 
projected to begin showing attaining monitoring values for the 2010 
SO2 NAAQS by the 2018 attainment date. As noted previously, 
some of the control measures will not be in place a full year prior to 
the attainment date as recommended in the 2014 SO2 
Nonattainment Guidance; a recommendation intended to provide data to 
evaluate the effect of the control strategy on air quality. Because the 
Area is currently attaining the 2010 SO2 NAAQS, EPA proposes 
to find that the full control strategy will be in place for an adequate 
time prior to the attainment date to ensure attainment of the NAAQS. In 
addition, by approving the RACM/RACT for Mosaic, and the supplemental 
controls for TECO, for the purposes of Florida's attainment planning, 
the control measures outlined in Tables 3 and 4 will become permanent 
and enforceable SIP measures to meet the requirements of the CAA.

E. RFP Plan

    Section 172(c)(2) of the CAA requires that an attainment plan 
includes a demonstration that shows reasonable further progress for 
meeting air quality standards will be achieved through generally linear 
incremental improvement in air quality. Section 171(1) of the Act 
defines RFP as ``such annual incremental reductions in emissions of the 
relevant air pollutant as are required by this part (part D) or may 
reasonably be required by EPA for the purpose of ensuring attainment of 
the applicable NAAQS by the applicable attainment date.'' As stated 
originally in the 1994 SO2 Guideline Document \15\ and 
repeated in the 2014 SO2 Nonattainment Guidance, EPA 
continues to believe that this definition is most appropriate for 
pollutants that are emitted from numerous and diverse sources, where 
the relationship between particular sources and ambient air quality are 
not directly quantified. In such cases, emissions reductions may be 
required from various types and locations of sources. The relationship 
between SO2 and sources is much more defined, and usually 
there is a single step between pre-control nonattainment and post-
control attainment. Therefore, EPA interpreted RFP for SO2 
as adherence to an ambitious compliance schedule in both the 1994 
SO2 Guideline Document and the 2014 SO2 
Nonattainment Guidance. The control measures for attainment of the 2010 
SO2 NAAQS included in the State's submittal have been 
modeled to achieve attainment of the NAAQS. The permits and the 
adoption of specific emissions limits and compliance parameters require 
these control measures and resulting emissions reductions to be 
achieved as expeditiously as practicable. As a result of an ambitious 
compliance schedule, projected to yield a sufficient reduction in 
SO2 emissions from the Mosaic and TECO facilities,

[[Page 57530]]

and resulting in modeled attainment of the SO2 NAAQS, EPA 
has preliminarily determined that FL DEP's SO2 attainment 
plan for the 2010 SO2 NAAQS fulfills the RFP requirements 
for the Hillsborough Area. Currently, the monitored SO2 
design value for the Hillsborough Area is below the NAAQS, and because 
of the modeled attainment with the selected control strategies, EPA 
does not anticipate future nonattainment, or that the Area will not 
meet the statutory October 4, 2018, attainment date. EPA therefore 
proposes to approve Florida's attainment plan with respect to the RFP 
requirements.
---------------------------------------------------------------------------

    \15\ SO2 Guideline Document, U.S. Environmental 
Protection Agency, Office of Air Quality Planning and Standards, 
Research Triangle Park, N.C. 27711, EPA-452/R-94-008, February 1994. 
Located at: http://www.epa.gov/ttn/oarpg/t1pgm.html.
---------------------------------------------------------------------------

F. Contingency Measures

    In accordance with section 172(c)(9) of the CAA, contingency 
measures are required as additional measures to be implemented in the 
event that an area fails to meet the RFP requirements or fails to 
attain a standard by its attainment date. These measures must be fully 
adopted rules or control measures that can be implemented quickly and 
without additional EPA or state action if the area fails to meet RFP 
requirements or fails to meet its attainment date and should contain 
trigger mechanisms and an implementation schedule. However, 
SO2 presents special considerations. As stated in the final 
2010 SO2 NAAQS promulgation on June 22, 2010 (75 FR 35520) 
and in the 2014 SO2 Nonattainment Guidance, EPA concluded 
that because of the quantifiable relationship between SO2 
sources and control measures, it is appropriate that state agencies 
develop a ``comprehensive program to identify sources of violations of 
the SO2 NAAQS and undertake an aggressive follow-up for 
compliance and enforcement.''
    Based on all the control measures that are planned for Mosaic and 
completed for TECO, FL DEP believes that the 2010 SO2 NAAQS 
can be achieved on a consistent basis. However, if a fourth exceedance 
of the SO2 NAAQS occurs during any calendar year, or upon a 
determination that the Hillsborough Area has failed to attain the NAAQS 
by the attainment date, Mosaic and TECO will immediately undertake full 
system audits of controlled SO2 emissions. Within 10 days, 
each source will independently submit a report to FL DEP summarizing 
all operating parameters for four 10-day periods up to and including 
the dates of the exceedances. These sources are required to deploy 
provisional SO2 emission control strategies within this 10-
day period and include ``evidence that these control strategies have 
been deployed, as appropriate'' in the report to FL DEP. FL DEP will 
then begin a 30-day evaluation of these reports to determine the cause 
of the exceedances, followed by a 30-day consultation period with the 
sources to develop and implement appropriate operational changes 
necessary to prevent any future violation of the NAAQS. Explicit 
measures addressed in Florida's April 3, 2015, SIP submittal are:
     Fuel switching to reduce or eliminate the use of sulfur-
containing fuels; and/or
     physical or operational reduction of production capacity.
    Florida may consider other options for additional controls if these 
measures are not deemed to be the most appropriate to address air 
quality issues in the Area.
    If a permit modification might be required to conform to applicable 
air quality standards, Florida will make use of the State's authority 
in Rule 62-4.080 to require permittees to comply with new or additional 
conditions. This authority would allow Florida to work directly with 
the source(s) expeditiously to make changes to permits. Subsequently, 
Florida would submit any relevant permit change to EPA as a source-
specific SIP revision to make the change permanent and enforceable. EPA 
notes that a contingency measure involving a revised permit or source-
specific SIP revision as an acceptable additional step, but according 
to CAA section 172(c)(9), a measure requiring further action by FL DEP 
or EPA (e.g., necessitating a revised permit and SIP revision) could 
not serve as the primary contingency measure.
    EPA is proposing to find that Florida's April 3, 2015, SIP 
submittal includes a comprehensive program to expeditiously identify 
the source of any violation of the SO2 NAAQS and for 
aggressive follow-up. Therefore, EPA proposes that the contingency 
measures submitted by Florida follow the 2014 SO2 
Nonattainment Guidance and meet the section 172(c)(9). EPA notes that 
Florida has further committed to pursue additional actions that may 
require a SIP revision if needed to address the exceedances.

G. Attainment Date

    Florida's modeling indicates that the Hillsborough Area will begin 
attaining the 2010 SO2 NAAQS by January 1, 2018, once the 
control strategy is completely implemented. This modeling does not 
provide for an attaining three-year design value by the proposed 
attainment date of October 4, 2018. However, expeditious implementation 
of the additional controls for the TECO source, combined with the 
actual emissions and implementation of scheduled RACM/RACT for the 
Mosaic source, has already provided for an attaining design value of 66 
ppb considering 2013-2015 data, and exhibited improved data in the 
years leading up to 2015.\16\ The recent design value is well under the 
NAAQS, and the ongoing compliance schedule for Mosaic control measures 
will help to assure that the area maintains the NAAQS in the future. 
Therefore, the area has attained the 2010 SO2 NAAQS, and is 
expected to continue to attain the NAAQS by the attainment date.
---------------------------------------------------------------------------

    \16\ The most recent quality-assured design values for each 
NAAQS are publicly available at https://www.epa.gov/air-trends/air-quality-design-values.
---------------------------------------------------------------------------

V. Proposed Action

    EPA is proposing to approve Florida's SO2 attainment 
plan for the Hillsborough Area. EPA has preliminarily determined that 
the SIP meets the applicable requirements of the CAA. Specifically, EPA 
is proposing to approve Florida's April 3, 2015, SIP submission, which 
includes the base year emissions inventory, a modeling demonstration of 
SO2 attainment, an analysis of RACM/RACT, a RFP plan, and 
contingency measures for the Hillsborough Area. Additionally, EPA is 
proposing to approve into the Florida SIP specific SO2 
emission limits and compliance parameters established for the two 
SO2 point sources impacting the Hillsborough Area.

VI. Statutory and Executive Order Reviews

    Under the CAA, the Administrator is required to approve a SIP 
submission that complies with the provisions of the Act and applicable 
federal regulations. See 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 CAA. 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

[[Page 57531]]

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 CAA; 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).
    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 as specified by Executive Order 13175 (65 
FR 67249, November 9, 2000), nor will it impose substantial direct 
costs on tribal governments or preempt tribal law.

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Reporting and recordkeeping requirements, Sulfur oxides.

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

    Dated: August 15, 2016.
Heather McTeer Toney,
Regional Administrator, Region 4.
[FR Doc. 2016-20118 Filed 8-22-16; 8:45 am]
 BILLING CODE 6560-50-P
```