[Federal Register Volume 82, Number 21 (Thursday, February 2, 2017)]
[Proposed Rules]
[Pages 9035-9054]
[FR Doc No: 2017-02193]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R10-OAR-2015-0131: FRL-9959-01-Region 10]

Air Plan Approval; AK, Fairbanks North Star Borough; 2006 PM2.5
Moderate Area Plan

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
approve state implementation plan (SIP) revisions submitted by the
State of Alaska (Alaska) to address Clean Air Act (CAA or Act)
requirements for the 2006 24-hour fine particulate matter
(PM2.5) national ambient air quality standards (NAAQS) in
the Fairbanks North Star Borough Moderate PM2.5
nonattainment area (FNSB NAA). Alaska submitted an attainment plan on
December 31, 2014, and made additional submissions and provided
clarifying information to supplement the attainment plan for the area
in January 2015, March 2015, July 2015, November 2015, March 2016,
November 2016, and January 2017 (hereafter, the initial submission and
all supplemental and clarifying information will be collectively
referred to as ``the FNSB Moderate Plan'').

DATES: Written comments must be received on or before March 6, 2017.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R10-
OAR-2015-0131, at http://www.regulations.gov. Follow the online
instructions for submitting comments. Once submitted, comments cannot
be edited or removed from Regulations.gov. The 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. The 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: Claudia Vaupel, Air Planning Unit,
Office of Air and Waste (OAW-150), Environmental Protection Agency,
Region 10, 1200 Sixth Ave, Suite 900, Seattle, WA 98101; telephone
number:<PHONE_NUMBER>, email address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION: Throughout this document, wherever ``we'',
``us'' or ``our'' are used, it is intended to refer to the EPA.

Table of Contents:

I. Background for the EPA's Proposed Action
    A. Regulatory Background
    B. FNSB NAA Background
II. The EPA's Evaluation of the FNSB Moderate Plan
    A. Emissions Inventories
    B. Pollutants Addressed
    C. Reasonably Available Control Measures/Reasonably Available
Control Technology
    D. Air Quality Modeling
    E. Demonstration That Attainment by the Moderate Area Attainment
Date Is Impracticable
    F. Reasonable Further Progress and Quantitative Milestones
    G. Contingency Measures
    H. Motor Vehicle Emissions Budgets
    I. FNSB NAA Exceptional Event Demonstrations and Concurrences
III. Proposed Action
IV. Incorporation by Reference
V. Statutory and Executive Order Reviews

I. Background for the EPA's Proposed Action

A. Regulatory Background

    On October 17, 2006, the EPA strengthened the 24-hour
PM2.5 NAAQS by lowering the level of the standards from 65
[micro]g/m\3\ to 35 [micro]g/m\3\ in order to provide increased
protection of public health (40 CFR 50.13).\1\ Epidemiological studies
have shown statistically significant correlations between elevated
PM2.5 levels and premature mortality. Other important
adverse health effects associated with elevated PM2.5
exposure include aggravation of respiratory and cardiovascular disease
(as indicated by increased hospital admissions, emergency room visits,
absences from school or work, and restricted activity days), changes in
lung function and increased respiratory symptoms. Individuals
particularly sensitive to PM2.5 exposure include older
adults, people with heart and lung disease, and children (78 FR 3088,
January 15, 2013). PM2.5 can be emitted directly into the
atmosphere as a solid or liquid particle (``primary PM2.5''
or ``direct PM2.5'') or can be formed in the atmosphere as a
result of various chemical reactions among precursor pollutants such as
nitrogen oxides, sulfur oxides, volatile organic compounds, and ammonia
(``secondary PM2.5'').\2\
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    \1\ See 71 FR 61224 (October 17, 2006). The EPA set the first
NAAQS for PM2.5 on July 18, 1997 (62 FR 36852), including
annual standards of 15.0 mg/m\3\ based on a 3-year average of annual
mean PM2.5 concentrations and 24-hour (daily) standards
of 65 mg/m\3\ based on a 3-year average of 98th percentile 24-hour
concentrations (40 CFR 50.7). In 2012, the EPA revised the annual
standard to lower its level to 12 mg/m\3\ (78 FR 3086, January 15,
2013, codified at 40 CFR 50.18). Unless otherwise noted, all
references to the PM2.5 standard in this notice are to
the 2006 24-hour standard of 35 mg/m\3\ codified at 40 CFR 50.13.
    \2\ See EPA, Regulatory Impact Analysis for the Final Revisions
to the National Ambient Air Quality Standards for Particulate Matter
(EPA-452/R-12-005, December 2012), p. 2-1.
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    Following promulgation of a new or revised NAAQS, the EPA is
required by section 107(d)(1) of the CAA to designate areas throughout
the United States as attainment, nonattainment, or unclassifiable for
the NAAQS. Nonattainment areas include both areas that are violating
the NAAQS, and nearby areas with emissions sources or activities that
contribute to violations in those areas. States with areas designated
nonattainment are required to prepare and submit a plan for attaining
the NAAQS in the area as expeditiously as practicable.
    The requirements for attainment plans for the 2006 24-hour
PM2.5 NAAQS include the general nonattainment area planning
requirements in CAA section 172 of title I, part D, subpart 1 (subpart
1) and the additional planning requirements specific to particulate
matter in CAA sections 188 and 189 of title I, part D, subpart 4
(subpart 4). The EPA has a longstanding general guidance document that
interprets the 1990 amendments to the CAA,

commonly referred to as the ``General Preamble'' (57 FR 13498, April
16, 1992). The General Preamble addresses the relationship between
subpart 1 and subpart 4 requirements and provides recommendations to
states for meeting statutory requirements for particulate matter
nonattainment planning. Specifically, the General Preamble explains
that requirements applicable to Moderate area nonattainment SIPs are
set forth in subpart 4, but such SIPs must also meet the general
nonattainment planning provisions in subpart 1, to the extent these
provisions ``are not otherwise subsumed by, or integrally related to,''
the more specific subpart 4 requirements. 57 FR 13538. On August 16,
1994, the EPA promulgated an addendum to the General Preamble providing
additional guidance for particulate matter nonattainment areas. 59 FR
41988. Additionally, on August 24, 2016, the EPA issued a final rule,
Fine Particulate Matter National Ambient Air Quality Standards: State
Implementation Plan Requirements (PM2.5 Implementation Rule,
81 FR 58009), to clarify our interpretations of the statutory
requirements that apply to PM2.5 nonattainment areas.
    The requirements of subpart 1 for attainment plans include, among
other things: (i) The section 172(c)(1) requirements to provide for the
implementation of reasonably available control measures (RACM) and
reasonably available control technology (RACT), and attainment of the
NAAQS; (ii) the section 172(c)(2) requirement to demonstrate reasonable
further progress (RFP); (iii) the section 172(c)(3) requirement for
emissions inventories; and (iv) the section 172(c)(9) requirement for
contingency measures.
    The subpart 4 requirements for Moderate areas are generally
comparable with the subpart 1 requirements and include: (i) Section
189(a)(1)(B) requirements to demonstrate attainment by the outermost
statutory Moderate area attainment date (i.e., the end of the sixth
calendar year following designation) or that attainment by such date is
impracticable; (ii) section 189(a)(1)(C) requirements to ensure RACM
will be implemented within four years of designation; (iii) section
189(c) requirements for RFP and quantitative milestones (QMs); and (iv)
section 189(e) control requirements for precursor emissions from major
stationary sources. In the event that the EPA reclassifies a Moderate
nonattainment area to Serious, subpart 4 imposes additional
requirements. In this action, the EPA is evaluating Alaska's attainment
plan for the FNSB NAA for compliance with the statutory and regulatory
requirements applicable to Moderate PM2.5 nonattainment
areas.

B. FNSB NAA Background

    The EPA designated a portion of the Fairbanks North Star Borough as
nonattainment for the 2006 24-hour PM2.5 NAAQS upon
evaluation of monitored air quality data for 2006-2008 (74 FR 58689,
November 13, 2009). Based on the 43 [mu]g/m\3\ 2006-2008 design value
at the State Office Building monitoring site, Alaska and the EPA
determined that a portion of the Fairbanks North Star Borough was
violating the NAAQS or contained sources contributing to a violation of
the NAAQS. Alaska noted that exceedances of the standard occur during
cold and stagnant weather patterns in the winter season and in the
summer months as the result of wildfires which Alaska flagged as
``exceptional events'' in accordance with the EPA's Exceptional Events
Rule at 40 CFR 50.14. At the time of designation, and also when Alaska
submitted the initial FNSB Moderate Plan, the regulatory monitor in the
FNSB NAA used by Alaska and the EPA was the monitor located at the
State Office Building in downtown Fairbanks. Accordingly, the analyses
that formed the basis of the FNSB Moderate Plan were premised upon data
from this monitor location. Unless otherwise noted, monitored data and
future year projections discussed in this action refer to the State
Office Building monitor location.
    As part of its attainment planning analysis, Alaska evaluated total
PM2.5 and speciated PM2.5 data from the State
Office Building monitor to help identify the appropriate emission
control strategy for the FNSB NAA. Alaska chose the 2006-2010 period
for the baseline representing conditions before emission controls and
calculated a baseline design value of 44.7 [mu]g/m\3\. During the most
polluted wintertime days from 2006-2010, Alaska found that ambient
PM2.5 in the area was dominated by organic carbon, followed
by sulfate. The results of Alaska's analysis of the average speciated
PM2.5 mass for these days are presented by chemical species
in table 1.\3\ Through its analysis of observed data and modeling
sources in the FNSB NAA, Alaska concludes that throughout the winter
months, residential wood heating is the major source of
PM2.5 and accounts for 60-80 percent of the observed
PM2.5. Sources of secondary sulfate account for 8-20 percent
of the observed PM2.5, and diesel and gasoline engines
account for 0-10 percent and 0-7 percent of the observed
PM2.5, respectively (FNSB Moderate Plan section III.D.5.8
and its associated appendix).
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    \3\ In section II.D of this proposal, we provide a more detailed
discussion of air quality modeling and the presentation of speciated
PM2.5 in the area in the FNSB Moderate Plan.

   Table 1--FNSB NAA Speciated PM2.5 Mass at the State Office Building
                                 Monitor
------------------------------------------------------------------------
                                                             Observed
                                                           concentration
                                                            on polluted
                         Species                            winter days
                                                            ([micro]g/
                                                               m\3\)
------------------------------------------------------------------------
PM2.5 Total.............................................            44.7
Organic Carbon..........................................            24.9
Elemental Carbon........................................             2.9
Sulfate.................................................             8.2
Nitrate.................................................             1.9
Ammonium................................................             3.6
Particle-Bound Water....................................             2.7
Other PM2.5.............................................             0.5
------------------------------------------------------------------------

    For planning and air quality modeling purposes, Alaska selected two
multi-day episodes in 2008 (January 23-February 10 and November 2-17).
Alaska explains that these episodes represent typical conditions in the
area when PM2.5 concentrations exceed the NAAQS, as well as
the conditions leading up to the high concentrations. The January-
February episode (19 days) represents a very cold episode. The average
daily temperatures were below -30[emsp14][deg]F for 6 of the 19 days.
As is typical of cold, stagnant episodes, the very cold days come in
batches, with warmer and less stagnant periods occurring in between.
The PM2.5 values for 10 of the days in this episode were
above the 35 [mu]g/m\3\ standard and 4 of them were above 60 [mu]g/
m\3\. The November episode (16 days) represents a relatively warm
episode. None of the days in this episode had an average daily
temperature below -10[emsp14][deg]F. The PM2.5 values for 6
of the days were above the 35 [mu]g/m\3\ standard and the highest days
were in the vicinity of 50 [mu]g/m\3\. Alaska did not use episodes with
violations during the summer months because those have historically
been associated with exceptional events, such as wildfires. For
purposes of the 2006 24-hour PM2.5 NAAQS, the EPA's
implementation regulations and guidance authorize states to focus their
analysis on representative multi-day episodes to help to determine the
most effective control strategy for a given nonattainment area.
    Alaska's control strategy in the FNSB NAA focuses on reducing
emissions from the key category of residential

heating sources that contribute to nonattainment in the area. The EPA
notes that Alaska's initial December 2014 submission cited a citizen's
referendum as a basis for not adopting and implementing many of the
control measures analyzed. The referendum, in place from 2010 to 2014,
limited the authority of the Fairbanks North Star Borough local
government (the Borough) to regulate sources related to residential
heating in any manner. Despite the limit on the Borough's authority,
the EPA notes that under section 110 of the CAA, the State of Alaska is
ultimately responsible for development and implementation of an
attainment plan to meet the NAAQS by the attainment date. The EPA does
not view the referendum to be a valid basis for asserting that a
control measure is unreasonable. In October 2014, the referendum
expired and the Borough began the process to adopt more stringent
control measures for emissions from this source category. However, it
was not possible for the Borough to enact these measures and for Alaska
to adopt them into the SIP by the December 31, 2014 submission
deadline. In February 2015, the Borough revised and strengthened its
curtailment program and enacted other control measures that Alaska
adopted for inclusion in the FNSB Moderate Plan and submitted to the
EPA for review in a November 22, 2016 supplementary submission.
    The EPA promulgated the nonattainment designation for the FNSB NAA
based on data from the State Office Building monitor, which was the
monitor that at the time had the requisite 3 years of complete, quality
assured data for the regulatory purpose of calculating the design value
for the area. Accordingly, Alaska has conducted its analyses and
developed the FNSB Moderate Plan using the data from the regulatory
monitor at the State Office Building. The EPA notes that an additional
monitor located at the North Pole Fire Station became a regulatory
monitor in 2015, subsequent to the initial submission of the FNSB
Moderate Plan. The North Pole Fire Station monitor currently records
the highest values in the FNSB NAA and had a 2013-2015 design value of
124 [mu]g/m\3\.
    On December 16, 2016, the EPA proposed to find that the FNSB NAA
did not attain by the latest permissible statutory Moderate area
attainment date of December 31, 2015, and proposed to reclassify the
area from Moderate to Serious pursuant to CAA section 188(b)(2). See 81
FR 91088. If the FNSB NAA is reclassified to Serious, Alaska will be
required to submit a Serious area attainment plan by December 31, 2017.
Although not used for the nonattainment designation or as part of the
FNSB Moderate Plan, the EPA expects that the data from the North Pole
Fire Station monitor will be included in the analyses for the
development of a Serious area attainment plan for the FNSB NAA.

II. The EPA's Evaluation of the FNSB Moderate Plan

    On December 31, 2014, Alaska submitted its initial Moderate area
attainment plan for the FNSB NAA. Alaska made additional submissions
and provided clarifying information to supplement the attainment plan
in January 2015, March 2015, July 2015, November 2015, March 2016,
November 2016, and January 2017 (as previously noted, the initial
submission and all supplemental and clarifying information will be
collectively referred to as ``the FNSB Moderate Plan'').
    The primary control strategy in the FNSB Moderate Plan is to reduce
emissions from residential wood combustion. The FNSB Moderate Plan
includes emissions inventories, an evaluation of precursors for control
in the area, RACM/RACT demonstrations for direct PM2.5 and
precursors, a demonstration that attainment by the December 31, 2015
attainment date is impracticable, QM and RFP requirements, and
contingency measures. Each of these elements is discussed below.

A. Emissions Inventories

1. Requirements for Emissions Inventories
    Section 172(c)(3) of the CAA requires a state with an area
designated as nonattainment to submit a ``comprehensive, accurate,
current inventory of actual emissions from all sources of the relevant
pollutant'' for the nonattainment area. By requiring an accounting of
actual emissions from all sources of the relevant pollutants in the
area, this section provides for the base year inventory to include all
emissions from sources in the nonattainment area that contribute to the
formation of a particular NAAQS pollutant. For the 2006 24-hour
PM2.5 NAAQS, this includes direct PM2.5
(condensable and filterable) as well as the precursors to the formation
of secondary PM2.5: Nitrogen oxides (NOX), sulfur
dioxide (SO2), volatile organic compounds (VOCs), and
ammonia (NH3). 40 CFR 51.1008; 81 FR 58028. Inclusion of
PM2.5 and all of the PM2.5 precursors in the
emissions inventory is necessary in order to inform other aspects of
the attainment plan development process, such as ascertaining which
pollutants a state must control in order to attain the NAAQS in the
area expeditiously.
    In addition to the base year inventory submitted to meet the
requirements of CAA section 172(c)(3), the state must also submit
future projected inventories for the projected attainment year and each
QM year, and any other year of significance for meeting applicable CAA
requirements. Projected emissions inventories for future years must
account for, among other things, the ongoing effects of economic growth
and adopted emissions control requirements, and are expected to be the
best available representation of future emissions. The SIP submission
should include documentation explaining how the state calculated the
emissions data for the base year and projected inventories. The
specific PM2.5 emissions inventory requirements are set
forth in 40 CFR 51.1008. The EPA has provided additional guidance for
developing PM2.5 emissions inventories in Emissions
Inventory Guidance for Implementation of Ozone and Particulate Matter
National Ambient Air Quality Standards (NAAQS) and Regional Haze.\4\
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    \4\ The EPA's Emissions Inventory Guidance for Implementation of
Ozone and Particulate Matter National Ambient Air Quality Standards
(NAAQS) and Regional Haze is available at https://www.epa.gov/air-emissions-inventories/emissions-inventory-guidance-documents.
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2. Emissions Inventories in the FNSB Moderate Plan
    The emissions inventories for the FNSB NAA are discussed in the
FNSB Moderate Plan section III.D.5.6 and appendix III.D.5.6. The FNSB
Moderate Plan has three emissions inventories for the area: The 2008
base year, the 2015 projected inventory for the Moderate area
attainment date, and the projected inventory for the 2017 QM year. In
addition, Alaska developed a projected emissions inventory for 2019 for
informational purposes to facilitate development of the attainment
plan. Each inventory lists direct PM2.5 emissions and
emissions of all PM2.5 precursors (NOX, VOCs,
NH3, and SO2). The 2008 and 2015 inventories for
the FNSB NAA include separately reported filterable and condensable
components of direct PM2.5 emissions. Alaska provided
inventories from all sources in the FNSB NAA, including stationary
point sources, stationary nonpoint (area sources), onroad mobile
sources and nonroad mobile sources.
    The inventories are based on emissions estimated during the two

2008 episodes that represent weather conditions when exceedances of the
2006 24-hour PM2.5 NAAQS typically occur. The inventory is
an average of emissions across all days in the two episodes. It
represents the average-season-day emissions, in which the emission
inventory season is the wintertime episodes of cold and calm weather
that coincide with exceedances of the standard.
    Alaska estimated winter episode average-season-day emissions for
the FNSB NAA based on a gridded inventory of actual or projected
emissions developed over an area larger than the FNSB NAA for air
quality modeling. The emissions were calculated for the FNSB NAA by
summing the emissions from grid cells within the area.
a. 2008 Base Year Emissions Inventory
    Alaska selected the year 2008 as the base year of the emissions
inventory. The selection of 2008 as a base year is consistent with
emissions inventory requirements because it is one of the three years
that the EPA used for calculating the design value for the 2006 24-hour
PM2.5 NAAQS designations. 40 CFR 51.1008(a)(1)(i); 81 FR
58028. This inventory provides the basis for the control measure
analysis, and for the RFP and impracticability demonstrations in the
FNSB Moderate Plan. A summary of the 2008 base year winter episode
average-season-day emissions inventory for the FNSB NAA is listed in
table 2 in tons per day (tpd).
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    \5\ Alaska reported direct PM2.5 condensable and
filterable emissions for point sources as 0.828 tpd and 0.686 tpd,
respectively (see the November 3, 2016 clarification in the docket
for this action). Alaska notes that, when accounting for the
condensable component of direct PM2.5 emissions in its
clarification, direct PM2.5 emissions from Stationary
Point (actual) increased from 1.412 tpd to 1.515 tpd in the FNSB
NAA. Alaska states that the increase has a small effect on
PM2.5 concentrations, approximately 0.12 [mu]g/m\3\ due
to the relatively small contribution to total PM2.5
emissions from stationary point sources compared to area space-
heating sources.
    \6\ The 0.001 tpd discrepancy in the VOC and NH3
totals is due to rounding.

             Table 2--2008 Base Year FNSB NAA Winter Episode Average-Season-Day Emissions Inventory
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                                                      Winter episode average-season-day (tpd)
      Source type/category       -------------------------------------------------------------------------------
                                     PM2.5 \5\          SO2             NOX             VOC             NH3
----------------------------------------------------------------------------------------------------------------
Stationary Point (actual).......           1.515           8.167          13.285           0.096          <0.001
Nonpoint/Area...................           2.817           3.865           2.184          11.627           0.136
Onroad..........................           0.676           0.046           4.625           5.725           0.071
Nonroad.........................           0.027           0.077           1.088           0.451           0.003
                                 -------------------------------------------------------------------------------
    Total \6\...................           5.035          12.155          21.182          17.898           0.210
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    Stationary Point Sources: Alaska included the actual emissions of
six major stationary point sources in the emissions inventory. Actual
emissions were based on historically recorded facility operating
throughput or continuous emissions monitoring systems for the two 2008
representative pollution episodes selected for planning purposes.
Alaska defines the ``major source'' thresholds for reporting annual
emissions as the potential to emit 100 tons annually for any relevant
criteria air pollutant consistent with the EPA's Air Emissions
Reporting Requirements, 40 CFR part 51, subpart A. Minor and synthetic
minor sources (5 to 99 tons per year) were initially included in the
stationary point sources category to ensure that smaller sources
located within the nonattainment area just below the 100 ton per year
major source threshold were also identified to determine if their
emission levels might warrant inclusion in the inventory as stationary
point sources. Those minor and synthetic minor sources that were not
identified as stationary point sources were included in emissions
inventory in the nonpoint/area sources category.
    Nonpoint/Area Sources: In the FNSB NAA, emissions from various
sources used to heat residential and commercial buildings are
cumulatively the largest source of primary PM2.5 emissions
during PM2.5 episodes. This category, which Alaska refers to
as ``space-heating'' sources in the FNSB Moderate Plan, includes
sources such as hydronic heaters, wood stoves, pellet stoves, and
residential oil heating. Alaska estimated emissions differently for
space-heating sources than for other non-space heating area sources.
For the non-space heating area sources, data was projected from a 2005
emissions inventory with a population growth factor. The 2005 inventory
combined seasonally-adjusted local activity estimates with EPA emission
factors (see AP-42, Compilation of Air Pollution Emission Factors).
Alaska also used data from the 2008 National Emissions Inventory to
develop these estimates.
    For space-heating sources, Alaska used EPA emissions factors and
locally collected data to estimate emissions by heating device and fuel
type. Local activity data was gathered from a Fairbanks winter home
heating energy model, multiple residential wood heating surveys, a
Fairbanks wood species study, and emissions testing of Fairbanks
heating devices. Table 3 provides the space heating winter episode
average-season day emissions estimates by fuel type for the 2008 base
year emissions inventory for the FNSB NAA.

Table 3--PM2.5 Space Heating Nonpoint/Area Sources Emissions for 2008 Base Year Emissions Inventory for the FNSB
                                                       NAA
----------------------------------------------------------------------------------------------------------------
                                                      Winter episode average-season-day (tpd)
 Space heating device/fuel type  -------------------------------------------------------------------------------
                                       PM2.5            SO2             NOX             VOC             NH3
----------------------------------------------------------------------------------------------------------------
Wood............................           2.656           0.084           0.373          10.914           0.098
Oil.............................           0.056           3.719           1.617           0.088           0.003
Other...........................           0.043           0.062           0.192           0.056           0.035
                                 -------------------------------------------------------------------------------

    Total Space Heating \7\.....           2.756           3.865           2.182          11.058           0.136
----------------------------------------------------------------------------------------------------------------

    On-road Sources: The onroad emissions inventory consists of mobile
sources such as automobiles, trucks, buses, and motorcycles. It was
prepared using the EPA's Motor Vehicle Emissions Simulator
(MOVES2010a), which was the latest onroad mobile sources emissions
model available at the time Alaska started developing the attainment
plan inventory. Alaska used local fleet and fuel inputs and the
Fairbanks Metropolitan Area Transportation System travel demand model
to generate local vehicle travel activity estimates. The use of engine
block heaters to keep gasoline engines from freezing during winter
months is common in the FNSB NAA. Alaska explains that having such a
pre-warmed engine reduces the start emissions from these vehicles. The
MOVES2010a model does not normally account for the impacts of engine
block heaters on vehicle emissions. To account for the effects on
starting exhaust PM2.5 emissions from wintertime plug-in
block heater use in light-duty gasoline vehicles, Alaska made EPA-
approved modifications to the soak time distribution inputs contained
in the MOVES2010a default database. Alaska executed MOVES2010a with
locally developed inputs representative of wintertime conditions and
assumed default MOVES2010a activity for heavy-duty trucks.
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    \7\ The 0.001 tpd discrepancy in the PM2.5 total is
due to rounding.
---------------------------------------------------------------------------

    Nonroad Sources: Alaska used the EPA's NONROAD2008a model to
estimate emissions for the nonroad mobile sources. However, Alaska
substituted local inputs for the EPA's default values in cases where
locally derived data was available (e.g., snowmobiles and snow
blowers). Alaska estimated aircraft emissions with the Federal Aviation
Administration's Emission and Dispersion Modeling System and locomotive
emissions were estimated based on the EPA's emission factors for
locomotives.
b. Projected Year Emissions Inventory
    In addition to developing a 2008 base year inventory, Alaska
developed a projected year inventory for the statutory Moderate area
attainment year (2015), i.e., the sixth calendar year after designation
as a nonattainment area. This inventory was relevant to the
determination of whether it was impracticable for the FNSB NAA to
attain by December 31, 2015. Alaska also developed an informational
projected inventory for the anticipated Serious area attainment year
(2019), i.e., the tenth calendar year after designation as a
nonattainment area. Alaska used the same temporal period of emissions
based on a winter episode average-season-day, the same level of detail,
and separately reported the filterable and condensable fractions of
direct PM2.5. Alaska developed the two projected year
inventories by estimating the impact on emissions from anticipated
demographic and economic trends and already adopted federal, state and
local control measures. Alaska then incorporated incremental emissions
reductions expected to be achieved from the control measures adopted in
the FNSB Moderate Plan. The two projected year inventories forecasted
emissions for 2015 and 2019 for the same source categories of emissions
identified in the base year inventory and were developed to support air
quality modeling, demonstrate reasonable progress on reducing
emissions, and to establish emission reduction milestone targets for
2017. A summary of the FNSB NAA 2015 projected winter episode average-
season-day emissions inventory is provided in table 4. Table 5 provides
emissions estimates from space heating sources by fuel type for the
FNSB NAA winter episode average-season day for the 2015 projected
emissions inventory.
---------------------------------------------------------------------------

    \8\ Alaska reported direct PM2.5 condensable and
filterable emissions for point sources as 0.828 tpd and 0.686 tpd,
respectively (see the November 3, 2016 clarification in the docket
for this action). Alaska notes that, when accounting for the
condensable component of direct PM2.5 emissions in its
clarification, direct PM2.5 emissions from Stationary
Point (actual) increased from 1.412 tons/day to 1.515 tons/day in
the FNSB NAA. Alaska states that the increase has a small effect on
PM2.5 emissions levels, approximately 0.12 [mu]g/m\3\ due
to the relatively small contribution to total PM2.5
emissions from stationary point sources compared to area space-
heating sources.

             Table 4--2015 Projected FNSB NAA Winter Episode Average-Season-Day Emissions Inventory
----------------------------------------------------------------------------------------------------------------
                                                      Winter episode average-season-day (tpd)
      Source type/category       -------------------------------------------------------------------------------
                                     PM2.5 \8\          SO2             NOX             VOC             NH3
----------------------------------------------------------------------------------------------------------------
Stationary Point (actual).......           1.515           8.167          13.285           0.096          <0.001
Nonpoint/Area...................           2.505           4.268           2.379           9.070           0.125
Onroad..........................           0.461           0.017           2.503           3.405           0.051
Nonroad.........................           0.025           0.082           1.062           0.403           0.003
                                 -------------------------------------------------------------------------------
    Total.......................           4.506          12.534          19.229          12.974           0.179
----------------------------------------------------------------------------------------------------------------

Table 5--PM2.5 Space Heating Nonpoint/Area Sources Emissions for 2015 Projected Emissions Inventory for the FNSB
                                                       NAA
----------------------------------------------------------------------------------------------------------------
                                                      Winter episode average-season-day (tpd)
 Space heating device/fuel type  -------------------------------------------------------------------------------
                                       PM2.5            SO2             NOX             VOC             NH3
----------------------------------------------------------------------------------------------------------------
Wood............................           2.330           0.084           0.373           8.308           0.085

Oil.............................           0.063           4.118           1.809           0.099           0.003
Other...........................           0.047           0.066           0.194           0.061           0.036
                                 -------------------------------------------------------------------------------
    Total Space Heating \9\.....           2.440           4.268           2.376           8.467           0.125
----------------------------------------------------------------------------------------------------------------

3. The EPA's Evaluation and Proposed Action: Emission Inventories
    The EPA has reviewed the results, procedures, and methodologies for
the FNSB NAA emissions inventories. The EPA has determined that the
2008 base year inventory and the 2015 projected inventory are based on
the most current and accurate information available to Alaska at the
time the FNSB Moderate Plan and its inventories were being developed.
The selection of 2008 for the base year inventory is also appropriate
because it reflects one of the three years of data used by the EPA in
the designation process for this area. The EPA finds the episodic
approach that Alaska used for the emissions inventories to be
consistent with the PM2.5 Implementation Rule in which the
EPA stated that an episodic period developed in order to reflect
periods of higher emissions during periods of high ambient
PM2.5 can help, in some situations, to ensure the
nonattainment area inventory reflects the emissions conditions that led
to the nonattainment designation for the area. 81 FR 58030.
Additionally, the 2008 and 2015 inventories sufficiently provide
separately reported PM2.5 condensable and filterable
emissions as required in 40 CFR 51.1008(a)(1)(iv) and (a)(2)(iv). The
inventories comprehensively address all source categories in the FNSB
NAA and Alaska used appropriate procedures to develop the inventories.
In addition, Alaska developed the 2015 projected inventory based on the
2008 base year inventory and accounted for projected growth and
reductions in emissions. We are therefore proposing to approve the 2008
base year emissions inventory for the FNSB NAA as meeting the
requirements of CAA section 172(c)(3) and 40 CFR 51.1008(a)(1), and we
are proposing to approve the 2015 projected year inventory as meeting
the requirements of 40 CFR 51.1008(a)(2). We are also proposing to find
that the 2008 base year inventory in the FNSB Moderate Plan provides an
adequate basis for the control strategy analysis, the impracticability
demonstration, and demonstrating RFP (discussed below in sections II.C,
E and F, respectively).
---------------------------------------------------------------------------

    \9\ The 0.001 tpd discrepancy in the VOC and NH3
totals is due to rounding.
---------------------------------------------------------------------------

B. Pollutants Addressed

1. Requirements for the Control of Direct PM2.5 and
Precursors
    The composition of PM2.5 is complex and highly variable
due in part to the large contribution of secondary PM2.5 to
total fine particle mass in most locations, and to the complexity of
secondary particle formation processes. A large number of possible
chemical reactions, often non-linear in nature, can convert gaseous
SO2, NOX, VOCs and NH3 to
PM2.5, making them precursors to PM2.5.\10\
Formation of secondary PM2.5 may also depend on atmospheric
conditions, including solar radiation, temperature, and relative
humidity, and the interactions of precursors with preexisting particles
and with water and ice cloud or fog droplets.\11\
---------------------------------------------------------------------------

    \10\ EPA, Air Quality Criteria for Particulate Matter (EPA/600/
P-99/002aF, October 2004), Chapter 3.
    \11\ EPA, Regulatory Impact Analysis for the Final Revisions to
the National Ambient Air Quality Standards for Particulate Matter
(EPA-452/R-12-005, December 2012), p. 2-1.
---------------------------------------------------------------------------

    The EPA interprets the CAA to require that a state must evaluate
sources of all four PM2.5 precursors for regulation, and
impose such regulations, unless it provides a demonstration
establishing that it is either not necessary to regulate a particular
precursor in the nonattainment area at issue in order to attain by the
attainment date, or that emissions of the precursor do not make a
significant contribution to PM2.5 levels that exceed the
standard. See 81 FR 58017. The provisions of subpart 4 do not define
the term ``precursor'' for purposes of PM2.5, nor do they
explicitly require the control of any specifically identified
particulate matter precursor. The definition of ``air pollutant'' in
CAA section 302(g), however, provides that the term ``includes any
precursors to the formation of any air pollutant, to the extent the
Administrator has identified such precursor or precursors for the
particular purpose for which the term `air pollutant' is used.'' The
EPA has identified SO2, NOX, VOCs, and
NH3 as precursors to the formation of PM2.5. 40
CFR 51.1000. Accordingly, the attainment plan requirements
presumptively apply to emissions of direct PM2.5 and all
four precursor pollutants from all types of stationary, area, and
mobile sources, except as otherwise provided in the Act (i.e., CAA
section 189(e)).
    Section 189(e) of the Act requires that the control requirements
for major stationary sources of direct PM10 also apply to
major stationary sources of PM10 precursors, except where
the Administrator determines that such sources do not contribute
significantly to PM10 levels that exceed the standard in the
area. By definition, PM10 includes PM2.5. Section
189(e) contains the only express exception to the control requirements
under subpart 4 (e.g., requirements for RACM and RACT, best available
control measures (BACM) and best available control technology (BACT),
most stringent measures, and nonattainment new source review) for
sources of direct PM2.5 and PM2.5 precursor
emissions.
    Although section 189(e) explicitly addresses only major stationary
sources, the EPA interprets the Act as authorizing it also to
determine, under appropriate circumstances, that regulation of specific
PM2.5 precursors from other source categories in a given
nonattainment area is not necessary. See 81 FR 58018. For example,
under the EPA's interpretation of the control requirements that apply
to stationary, area, and mobile sources of PM2.5 precursors
area-wide under CAA section 172(c)(1) and subpart 4, the EPA's recently
promulgated PM2.5 Implementation Rule provides states the
option of submitting a demonstration to show that emissions of a
precursor do not contribute significantly to PM2.5 levels
which exceed the NAAQS in a particular nonattainment area. 40 CFR
51.1006. If the EPA were to approve a state's precursor demonstration,
the state would not need to address the precursor in meeting certain
plan

requirements, such as the imposition of RACM/RACT level control on
sources of such precursor emissions.
    The state has the option of performing either (1) a comprehensive
precursor demonstration to establish that the state does not need to
address the precursor in the attainment plan for purposes of the
control strategy, RFP, QMs and associated reports, contingency
measures, motor vehicle emissions budget, or regional emissions
analyses in transportation conformity determinations, or (2) a major
stationary source precursor demonstration to justify the exclusion of
existing major sources from control requirements for the applicable
precursor. Both types of precursor demonstrations must include a
concentration-based analysis, in which the state evaluates the impact
of each precursor on ambient PM2.5 levels in the
nonattainment area. A concentration-based analysis may be sufficient
for the EPA to approve the demonstration, on a precursor-by-precursor
basis. The state also has the option of providing an additional
sensitivity-based analysis to show that changes in the emissions of a
particular precursor would not result in significant changes in ambient
PM2.5 in the area. 40 CFR 51.1006(a)(iii). The EPA's Draft
PM2.5 Precursor Demonstration Guidance (Precursor
Demonstration Guidance) recommends calculating the relative precursor
impact in the context of the Software for the Modeled Attainment Test
(SMAT) methodology so that the results are applicable to measured
PM2.5 in the area.\12\
---------------------------------------------------------------------------

    \12\ The Precursor Demonstration Guidance is available at
https://www.epa.gov/sites/production/files/2016-11/documents/transmittal_memo_and_draft_pm25_precursor_demo_guidance_11_17_16.pdf.

---------------------------------------------------------------------------

2. Direct PM2.5 and Precursors in the FNSB Moderate Plan
    In the FNSB Moderate Plan, Alaska discusses the five pollutants
that contribute to the mass of the ambient PM2.5 (i.e.,
NH3, NOX, SO2, VOCs, and direct
PM2.5). Because Alaska developed the attainment plan before
the EPA proposed a new implementation rule in 2015 (80 FR 15340, March
23, 2015), and before the EPA issued the Precursor Demonstration
Guidance in 2016, the FNSB Moderate Plan includes a variety of
information on precursor impacts on PM2.5 concentrations in
the FNSB NAA. Following the EPA's past approach to regulation of
precursors for purposes of the PM10 NAAQS, Alaska submitted
technical analyses to establish that regulation of specific precursors
would not be an effective attainment strategy in the FNSB NAA. After
the release of the PM2.5 Implementation Rule and the
Precursor Demonstration Guidance, Alaska included information in its
January 6, 2017 clarification document (2017 Clarification) to help the
EPA interpret its FNSB Moderate Plan in light of the new rule and
guidance (see FNSB Moderate Plan appendix III.D.5.7 and the 2017
Clarification). Specifically, the FNSB Moderate Plan contains
information necessary to evaluate a comprehensive precursor
demonstration for all sources of VOCs and a major stationary source
precursor demonstration for NOX. The FNSB Moderate Plan
reports speciated PM2.5 data from the State Office Building
monitor that can be compared to the recommended insignificance
thresholds in the Precursor Demonstration Guidance. These data are the
results of the SMAT methodology and are representative of precursor
concentrations for the baseline design value of 44.7 [mu]g/m\3\.
    Alaska's VOC precursor demonstration examined both ambient and
modeled PM2.5 species data to help evaluate the formation of
secondary organic aerosols (SOA) from VOC emissions in this specific
nonattainment area. Appendix III.D.5.8 of the FNSB Moderate Plan
presents several analyses involving observed chemical data, tracers of
source categories, source apportionment techniques, and independent
modeling efforts. Under low sunlight conditions and cold temperatures,
the photochemistry normally associated with SOA production is
limited.\13\ Alaska explained that VOCs that are emitted likely either
remain mostly unreacted in the gas phase or condense and are evaluated
for emission control as the condensable part of direct
PM2.5.
---------------------------------------------------------------------------

    \13\ Joyce, P. L., von Glasow, R., and Simpson, W. R.: The fate
of NOX emissions due to nocturnal oxidation at high
latitudes: 1-D simulations and sensitivity experiments, Atmos. Chem.
Phys., 14, 7601-7616, doi:10.5194/acp-14-7601-2014, 2014.
---------------------------------------------------------------------------

    In appendix III.D.5.7 of the FNSB Moderate Plan and in the 2017
Clarification, Alaska did not directly determine the impact of VOCs on
PM2.5 from speciated monitoring data alone because it is
difficult to distinguish organic carbon from direct PM2.5
and secondary organic carbon formed from VOC chemistry. Instead, the
precursor demonstration relies on the predicted concentrations of SOA
compounds from the Community Multiscale Air Quality (CMAQ) model.
Alaska summed the episode-averaged concentrations of all 19 secondary
organic compounds produced from the CMAQ modeling results at the State
Office Building monitor location. The sum of all modeled SOA species
represents the impact from all VOC sources on PM2.5 at the
monitor. Alaska reported the modeled PM2.5 concentration
from VOC precursors was 0.0006 [mu]g/m\3\ and 0.007 [mu]g/m\3\ for the
2008 base modeling year and 2015 modeling year cases, respectively.
    Alaska also submitted a precursor demonstration for NOX
that modeled the PM2.5 impact from major stationary sources
of NOX in the FNSB NAA (i.e., a major stationary source
demonstration, rather than a comprehensive precursor demonstration with
respect to all sources of NOX emissions in the area). Id. In
support of the NOX major stationary source demonstration,
Alaska performed a brute force CMAQ ``zero-out'' modeling analysis, as
described in the FNSB Moderate Plan and 2017 Clarification, and as
recommended by the Precursor Demonstration Guidance. The CMAQ modeling
results are compared between one model run in which all emission
sources are included and a second ``zero out'' model run in which all
major stationary source NOX emissions in the NAA are assumed
to be zero. The model results are processed through the SMAT
methodology. The difference in PM2.5 mass projected at the
State Office Building monitor location between the two model
simulations represents the estimated impact of major stationary source
NOX to ambient PM2.5 in the FNSB NAA. For the
2015 model simulation, the impact from major stationary source
NOX to PM2.5 at the State Office Building monitor
location is 0.5 [mu]g/m\3\ averaged across all modeled episode days
(all days within the episode produce PM2.5 less than 0.6
[mu]g/m\3\).
3. The EPA's Evaluation and Proposed Action: Pollutants Addressed
    In Alaska's comprehensive precursor demonstration for VOCs using a
concentration-based contribution analysis, the modeled PM2.5
concentration from VOC precursors (0.0006 [mu]g/m\3\ and 0.007 [mu]g/
m\3\ for the 2008 base modeling year and 2015 modeling year cases,
respectively) is well below 1.3 [mu]g/m\3\ on a 24-hour basis, the
recommended contribution threshold for the 24-hour PM2.5
NAAQS, for precursor demonstrations identified in the Precursor
Demonstration Guidance. Even the day with the highest modeled
PM2.5 production from VOCs produces only 1 percent of the
insignificance threshold at the State Office Building. Alaska did not
calculate the relative precursor impact in the context of the SMAT
methodology because the VOC

precursor impact on PM2.5 was so far below the recommended
insignificance threshold in the Precursor Demonstration Guidance that a
SMAT adjustment was inconsequential. The modeling results are
consistent with Alaska's full suite of ambient data analyses, source
apportionment techniques, and modeling efforts, all of which indicate
very limited photochemical pathways and inconsequential concentrations
of SOA in the FNSB NAA in the winter (See FNSB Moderate Plan appendix
III.D.5.8).
    The FNSB Moderate Plan does not provide for a NOX
comprehensive precursor demonstration because the measured ammonium
nitrate at the State Office Building monitor (2.5 [mu]g/m\3\) is above
the recommended 24-hour PM2.5 contribution threshold for
precursor demonstrations (1.3 [mu]g/m\3\). In Alaska's major stationary
source precursor demonstration for NOX, the episode average
contribution of major stationary source NOX to
PM2.5 (0.5 [mu]g/m\3\) is less than one half of the
recommended insignificance threshold (1.3 [mu]g/m\3\) for precursor
demonstrations in the Precursor Demonstration Guidance. The low amount
of PM2.5 from major stationary source NOX
precursor emissions is consistent with other aspects of the FNSB
Moderate Plan. As with VOCs, the photochemistry to produce large
amounts of particle-bound nitrate is limited during wintertime
pollution events in the FNSB NAA. Id. Furthermore, major stationary
sources with elevated stacks emit most of their precursors into the
extremely stable atmosphere present during wintertime pollution events.
Only a fraction of the elevated plumes returns to ground level in the
FNSB NAA where air quality monitors are located and much less than
might be expected in most parts of the lower 48 states. Therefore, the
analysis indicates that NOX emissions from these sources
will have very little impact on ground level chemistry and thus on
secondary PM2.5 formation in the FNSB NAA.
    Based on a review of the information provided by Alaska, we propose
to approve Alaska's precursor demonstrations for major stationary
source emissions of NOX and for all sources of VOCs within
the FNSB NAA. We propose to approve Alaska's analysis and conclusion
that it is not necessary to evaluate and impose controls on sources of
VOCs or on major stationary sources of NOX in the control
strategy for the FNSB Moderate Plan. Consistent with the requirements
of subpart 4, Alaska must include all other PM2.5 precursors
(NH3 and SO2) and NOX from sources
other than major stationary sources in the evaluation of potential
RACM/RACT control measures, RFP, QM, contingency measures, and in the
impracticability demonstration. We discuss Alaska's evaluation of
potential control measures for sources of NH3,
SO2, and NOX, as well as direct PM2.5,
in the following section.

C. Reasonably Available Control Measures/Reasonably Available Control
Technology

1. Requirements for RACM/RACT
    The general SIP planning requirements for nonattainment areas under
subpart 1 include CAA section 172(c)(1), which requires implementation
of all RACM, including RACT. The terms RACM and RACT are not further
defined within subpart 1, but past guidance has described ``reasonable
available'' controls as those controls that are technologically and
economically feasible, and necessary for attainment in a given area.
See 57 FR 13560. The provision explicitly requires that such measures
must provide for attainment of the NAAQS in the area covered by the
attainment plan.
    The SIP planning requirements for particulate matter nonattainment
areas in subpart 4 likewise impose upon states an obligation to develop
attainment plans that implement RACM and RACT on appropriate sources
within a nonattainment area. Section 189(a)(1)(C) requires that states
with areas classified as Moderate nonattainment areas have SIP
provisions to assure that RACM and RACT level controls are implemented
by no later than four years after designation of the area. As with
subpart 1, the terms RACM and RACT are not specifically defined within
subpart 4, and the provisions of subpart 4 do not identify specific
control measures that must be implemented to meet the RACM and RACT
requirements. However, past policy has described RACM (including RACT)
as those measures that are technologically and economically feasible
and needed for expeditious attainment of the standard. 81 FR 58034. The
EPA's recent PM2.5 Implementation Rule provides a process
for developing an attainment plan control strategy for purposes of
meeting the RACM and RACT requirements.\14\ See 40 CFR 51.1009.
---------------------------------------------------------------------------

    \14\ The development of the RACM and RACT requirements in the
PM2.5 Implementation Rule was informed by the EPA's
longstanding guidance in the General Preamble providing
recommendations for appropriate considerations for determining what
control measures constitute RACM and RACT for purposes of meeting
the statutory requirements of subpart 4. See 81 FR 58034.
---------------------------------------------------------------------------

    To meet the Moderate area control strategy requirements, a state
first needs to identify all sources of direct PM2.5 and
precursor emissions in the nonattainment area, consistent with common
emission inventory development practices and requirements. 40 CFR
51.1009(a)(1). Next a state must identify existing and potential
control measures for each identified source or source category of
emissions. Id. at 51.1009(a)(2). The state's compilation of potential
control measures must be sufficiently broad to provide a basis for
identifying all technologically and economically feasible controls that
may be RACM or RACT. The state must identify potential control measures
for emissions of direct PM2.5 and each precursor from
relevant sources unless the state has provided an adequate
comprehensive demonstration for the nonattainment area at issue showing
that control of a particular precursor is not required, or provided an
adequate demonstration with respect to control of precursor emissions
from existing major stationary sources. Id. at 51.1009(a)(4)(i). For
any potential control measure identified, a state must evaluate the
technological and economic feasibility of adopting and implementing
such measure. Id. at 51.1009(a)(3). For purposes of evaluating
technological feasibility, a state may consider factors including but
not limited to operating processes and procedures, raw materials,
physical plant layout, and potential environmental impacts from the
adoption of controls. For purposes of evaluating economic feasibility,
a state may consider factors including but not limited to capital,
operating and maintenance costs and the cost effectiveness of a measure
(typically expressed in cost per ton of reduction). Id. States should
also evaluate control measures imposed in other nonattainment areas as
RACM and RACT as part of this analysis. For Moderate area plans that
demonstrate the area cannot attain by the Moderate area statutory
attainment date, the state is required to adopt all technologically and
economically feasible control measures. Id. at 51.1009(a)(4).
    CAA section 110(a)(2)(A) provides generally that each SIP ``shall
include enforceable emission limitations and other control measures,
means or techniques . . . as well as schedules and timetables for
compliance, as may be necessary or appropriate to meet the applicable
requirement of the Act.'' Section 172(c)(6) of the Act, which

applies specifically to nonattainment area plans, imposes comparable
requirements.\15\ Measures necessary to meet RACM/RACT and the
additional control measure requirements under section 172(c)(6) must be
adopted by Alaska in an enforceable form (57 FR 13541) and submitted to
the EPA for approval into the SIP under CAA section 110.
---------------------------------------------------------------------------

    \15\ The language in sections 110(a)(2)(A) and 172(c)(6) is
quite broad, allowing a SIP to contain any enforceable ``means or
techniques'' that the state and the EPA determine are ``necessary or
appropriate'' to meet CAA requirements, such that the area will
attain as expeditiously as practicable, but no later than the
designated date. Furthermore, the express allowance for ``schedules
and timetables'' demonstrates that Congress understood that all
required controls might not be in force when the EPA approves a SIP
submission, e.g., they could include measures to be implemented in a
future year. The EPA notes, however, that all SIP provisions must
meet applicable legal requirements, such as imposing emission
limitations that apply continuously and being practically and
legally enforceable.
---------------------------------------------------------------------------

2. RACM/RACT Analysis in the FNSB Moderate Plan
    In the FNSB Moderate Plan, Alaska explains the multi-step process
it undertook, consistent with the process set forth at 40 CFR 51.1009,
to evaluate and select control measures that would constitute RACM/RACT
in the FNSB NAA. Based on emissions inventory information and other
technical analyses, Alaska first identified source categories in the
FNSB NAA and associated emissions of PM2.5 and its
precursors. Alaska's approach to the RACM/RACT analysis targets
emissions that occur during the wintertime when stagnant air episodes
occur and concentrations of emissions build-up, leading to exceedances
of the 2006 24-hour PM2.5 NAAQS. Based on its assessment of
estimated source category contributions to ambient PM2.5.
Alaska proceeded to identify the following source categories for
further analysis: Residential wood heating, open burning, residential
fuel oil combustion, automobile and heavy-duty vehicle transportation,
and stationary point sources.
    Alaska developed a list of potential control measures for relevant
sources based on information compiled from various EPA guidance
documents, information received during Alaska's public process, and
information regarding controls that other states or the EPA have
identified as RACM or RACT in attainment plans in other nonattainment
areas. Alaska then evaluated control measures to determine if they are
technologically and economically feasible, which included consideration
of factors such as the emissions benefits and cost effectiveness of the
measures. Alaska's RACM/RACT analysis and control strategy are
presented in the FNSB Moderate Plan section III.D.5.7, appendix
III.D.5.7, and the 2017 Clarification; sections III.D.5.6, III.D.5.8,
and III.D.5.11 of the FNSB Moderate Plan also provide supporting
information.
a. Non-Point/Area Sources RACM/RACT Analysis in the FNSB Moderate Plan
    Alaska ascertained that the key category of areas sources (non-
point sources) in the FNSB NAA that requires imposition of control
measures to reach attainment of the 2006 24-hour PM2.5 NAAQS
is wood burning. Accordingly, Alaska's RACM/RACT analysis for the FNSB
NAA evaluated control measures for residential heating and open
burning. Alaska also evaluated control measures for transportation
sources.
    Residential Heating: Alaska identified and adopted a suite of
control measures as RACM/RACT for residential heating sources in the
FNSB NAA. The control measures include a changeout program that
incentivizes the removal or replacement of inefficient wood-fired
heating devices; a prohibition on certain fuels used in solid-fuel
fired heaters, including a requirement that only dry wood, with a
moisture content of 20 percent or less, can be used; curtailment of
solid-fuel fired heaters during polluted conditions; a 20 percent
opacity limit for solid-fuel fired heaters; the exclusion of owners of
newly constructed buildings from obtaining a ``no other adequate source
of heat'' determination; a wood seller wood-moisture disclosure
program; setback requirements for new installations of hydronic
heaters; and wood heating education and outreach programs to increase
public understanding and compliance with regulations and to encourage
efficient operation of wood heaters.
    The changeout program in the FNSB NAA provides subsidies up to
$4,000 to replace wood stoves, and up to $10,000 to replace hydronic
heaters, with cleaner burning certified devices (FNSB Moderate Plan
section III.D.5.7-3, III.D.5.6-50, table 5.6-18). Higher subsidies are
available for removal of a solid-fuel burning device and replacement
with a heating source that burns oil or natural gas. The changeout
program also provides incentives for removing (rather than replacing)
older uncertified devices. Subsidies to retrofit hydronic heaters to
reduce emissions were also offered. Between 2010 and 2014, Alaska
estimates that 3,365 solid-fuel fired heating devices were replaced and
888 devices were removed through the wood stove changeout program (FNSB
Moderate Plan section III.D.5.6-51, table 5.6-19).
    Alaska estimates that in the absence of a dry wood program, the
average moisture content of wood used in the FNSB NAA is 39.7 percent.
The requirement to burn only dry wood (moisture content of 20 percent
or less) will result in more efficient residential wood heating,
decreased fuel use, and reduced emissions (FNSB Moderate Plan section
III.D.5.6-45).
    The curtailment program in the FNSB NAA places restrictions on the
operation of solid-fuel fired heaters during certain ambient and
meteorological conditions (FNSB Moderate Plan section III.D.5.11 and
2017 Clarification). The solid-fuel fired heater curtailment alerts are
announced by local authorities based on forecasted PM2.5
concentrations in the three different air quality zones: Fairbanks,
North Pole, and Goldstream. The curtailment program includes one
voluntary and two mandatory stages. When PM2.5 ambient
levels are forecasted to reach or exceed 25 [micro]g/m\3\ or more in a
particular zone, a stage one alert is issued for that zone. During a
stage one alert, residents are asked to voluntarily curtail or stop
using solid-fuel heating devices, pellet stoves, waste oil devices, and
masonry heaters. When PM2.5 levels are forecasted to reach
35 [micro]g/m\3\ or more in a particular zone, a stage 2 alert is
issued for that zone. During a stage 2 alert, burning is only permitted
in U.S. EPA certified devices, EPA Phase II hydronic heaters with
PM2.5 annual average emissions ratings of 2.5 grams per hour
or less, masonry heaters, pellet stoves, and fireplaces. A stage 3
alert is issued when PM2.5 ambient levels are forecasted to
reach 55 [micro]g/m\3\. During a stage 3 alert, the use of solid-fuel
burning devices, masonry heaters, pellet-fueled appliances, cook
stoves, fireplaces, and waste oil devices is prohibited. The mandatory
restrictions imposed during stage 2 and 3 alerts do not apply during
periods of power failure or to buildings that have ``no other adequate
source of heat'' designations. During a stage 3 alert, the mandatory
restrictions do not apply when the temperature is below -15 [deg]F (as
recorded at the Fairbanks International Airport). Alaska included these
limitations in the mandatory curtailment program due to the unique
circumstances of the FNSB NAA, which experiences extreme winter
temperatures and has limited availability of alternative fuel sources
such as natural gas.

    The voluntary programs in the FNSB NAA are expected to increase
compliance with regulations and encourage behaviors that reduce
emissions. These programs include public awareness and education on
wood storage, heating device operation and maintenance, and curtailment
alert notifications (FNSB Moderate Plan section III.D.5.7-7 and 2017
Clarification). Alaska relied on these measures for a small portion of
the necessary emission reductions, consistent with EPA guidance for
voluntary measures.
    The residential heating control measures that Alaska identified as
RACM/RACT primarily reduce emissions of direct PM2.5. To
evaluate potential measures to reduce SO2 emissions, Alaska
conducted a RACM/RACT analysis for providing economic incentives to
encourage FNSB NAA residents that use heating oil to switch to low-
sulfur heating oil. Alaska determined that this control measure was not
cost effective at this time (FNSB Moderate Plan appendix III.D.5.7-57).
    Open Burning: Alaska identified and adopted prohibitions on open
burning during the wintertime as RACM/RACT for the FNSB NAA. Open
burning, including the use of burn barrels, is prohibited in the FNSB
NAA from November 1 through March 31. (FNSB Moderate Plan section
III.D.5.7-22).
    Transportation: Alaska identified and adopted a suite of
transportation control measures as RACM/RACT for the FNSB NAA. These
include measures providing for ``plug-in'' engine block heating,
programs to encourage the use of mass transit, federal motor vehicle
fuel economy standards, and federal and state diesel emissions
reduction programs.
b. Stationary/Point Sources RACM/RACT Analysis in the FNSB Moderate
Plan
    The FNSB NAA has six major stationary point sources. Alaska
evaluated these sources for potential PM2.5 and
SO2 control technologies. As discussed in section II.B.3 of
this proposal, Alaska demonstrated that VOCs and NOX
emissions from these major stationary sources do not contribute
significantly to violations of the 2006 24-hour PM2.5 NAAQS
in this area, consistent with the requirements of CAA section 189(e).
Alaska also excluded from consideration control technologies to address
NH3, which accounts for less than 0.001 tons per day of
emissions in the FNSB NAA.
    The six major stationary sources in the FNSB NAA are: Fort
Wainwright Central Heating Power Plant, Aurora Energy Chena Power
Plant, University of Alaska Fairbanks Campus Power Plant, GVEA North
Pole Power Plant, GVEA Zehnder Power Plant, and the Flint Hills North
Pole Refinery. Alaska's RACM/RACT analysis addressed 12 coal-fired
boilers, five gas turbines, and two dual-fuel fired boilers at these
facilities (FNSB Moderate Plan appendix III.D.5.7-64). The following is
a summary of the control measures that Alaska identified as RACM/RACT
for the stationary sources.
    Coal-fired Boilers: Alaska provided a detailed description of the
coal-fired units in the FNSB NAA including the existing controls and
the 2011 direct PM2.5 and SO2 emissions. Six of
the 12 coal-fired boilers are at the Fort Wainwright Central Heat and
Power Plant. The direct PM2.5 emissions for each of these
six units were less than 5 tons per year (tpy) and the SO2
emissions were between 87 and 171 tpy. The Aurora Energy Chena Power
Plant has four coal-fired boilers that share a common stack and exhaust
control system. The direct PM2.5 emissions for the combined
four units were 7.81 tpy and the SO2 emissions were 838.9
tpy. The remaining two coal-fired boilers are at the University of
Alaska Fairbanks Campus Power Plant. There are also two dual fuel-fired
boilers at this power plant that use gas and liquid fuel. The direct
PM2.5 emissions for each of these boilers were less than 5
tpy and the SO2 emissions for all of the boilers combined
were 281.7 tpy.
    Alaska identified fabric filters (baghouses) as RACM/RACT to
control direct PM2.5 emissions. With respect to
SO2, Alaska concluded that the use of low-sulfur fuels at
these stationary sources constitutes RACM/RACT in the FNSB NAA for
purposes of the 2006 24-hour PM2.5 NAAQS (FNSB Moderate Plan
appendix III.D.5.7-72).
    Gas Turbines: For the five gas turbines in the FNSB NAA, Alaska
analyzed the emissions of the individual units for potential RACM/RACT
level emissions controls. The GVEA North Pole Power Plant has three gas
turbines. Only one of these units runs at baseload throughout the year.
In 2011, the direct PM2.5 emissions for the baseload unit
were 16 tpy and the SO2 emissions were 1.9 tpy. The other
two units at the GVEA North Pole Power Plant operate during peak hours.
The direct PM2.5 emissions for each of these units were 16
and 131 tpy and the SO2 emissions were 42 and 326 tpy. The
remaining two gas turbines are at the GVEA Zehnder Power Plant and ran
a combined total of about 53 days in 2011. The direct PM2.5
emissions for these units were 11 and 16 tpy. The SO2
emissions for these units were 26 and 40 tpy.
    Alaska identified the use of low sulfur naphtha and light straight-
run (LSR) fuel as RACM/RACT level controls for the unit that runs at
baseload throughout the year. For the other four gas turbines, Alaska
determined that, in the FNSB NAA, the continued use of heavy fuel oil
constitutes RACM/RACT for these units. (FNSB Moderate Plan appendix
III.D.5.7-88-91).
    Dual Fuel-fired Boilers: Alaska provided an analysis of potential
control measures for the two dual-fired boilers at the University of
Alaska Fairbanks Campus Power Plant. Alaska analyzed the individual
units for RACM/RACT and provided the 2011 actual PM2.5 and
SO2 emissions for these units. From the combustion of fuel
oil, the SO2 emissions from these units were 17.7 and 11.2
tpy. For PM2.5, emissions were less than 5 tons per year.
Alaska concluded that, in the FNSB NAA, the use of No. 2 distillate
fuel constitutes RACM/RACT for these boilers. (FNSB Moderate Plan
appendix III.D.5.7-87).
c. Adopted Control Strategy in the FNSB Moderate Plan
    Alaska evaluated the different source categories in the FNSB NAA
for potential controls. In the case of the point sources, Alaska
determined that the existing level of control meets RACM/RACT
requirements. With respect to mobile sources, Alaska determined that
existing federal fuel and engine emission standards provide sufficient
levels of emission reduction from these sources for purposes of the
2006 24-hour PM2.5 NAAQS. In addition, however, Alaska
concluded that an existing local control measure to provide for plug-in
engine block heating is an appropriate RACM/RACT control measure for
vehicles in this area because it will provide needed reductions in
emissions during the critical winter episodes when NAAQS exceedances
occur in the FNSB NAA.
    Alaska's control strategy focuses primarily on imposing control
measures on the key sources contributing to nonattainment during the
winter season when exceedances of the 2006 24-hour PM2.5
NAAQS occur, i.e., residential wood heating. Alaska estimated that by
2015, the emissions reductions from the adopted control strategy in the
FNSB Moderate Plan would result in a 5.14 [mu]g/m\3\ reduction from the
baseline design value of 44.7 [mu]g/m\3\ at the State Office Building
monitor (FNSB Moderate Plan section III.D.5.8, table 5.8-12 and 2017
Clarification). The emissions reductions estimated from the control
strategy and the implementation

dates are summarized in the table below.

                                  Table 6--FNSB Moderate Plan Control Strategy
----------------------------------------------------------------------------------------------------------------
                                                                        Emission reductions
                         Control measure                         -------------------------------- Implementation
                                                                        tpd         [mu]g/m\3\         dates
----------------------------------------------------------------------------------------------------------------
Voluntary Measures:
    --Transportation............................................    PM2.5: 0.004            0.04       2001-2015
    --Residential Heating.......................................    PM2.5: 0.055            0.50
Wood Heating Device Incentives:
    --Changeout Program.........................................    PM2.5: 0.397            3.10       2010-2012
    --Hydronic Heater Retrofits.................................     SO2: -0.014
                                                                      NOX: 0.033
                                                                      NH3: 0.014
Energy Efficiency Measures......................................   PM2.5: <0.002           <0.02            2008
Opacity Limit...................................................   PM2.5: <0.001           <0.01            2015
Open Burning....................................................   PM2.5: <0.001           <0.01            2015
Vehicle/Device Turnover (SIP):
    --Federal Motor Vehicle Control Program (~95% of reductions)    PM2.5: 0.135            1.50
    --Uncertified Wood Device Turnover (~5% of reductions)......
        Totals..................................................    PM2.5: 0.591            5.14
                                                                     SO2: -0.014
                                                                      NOX: 0.033
                                                                      NH3: 0.014
----------------------------------------------------------------------------------------------------------------

3. The EPA's Evaluation and Proposed Action: RACM/RACT
    The EPA proposes to approve the control strategy in the FNSB
Moderate Plan. In the FNSB Moderate Plan, Alaska appropriately followed
a process to analyze and select RACM/RACT level controls for this
specific nonattainment area consistent with the procedures for Moderate
nonattainment areas identified at 40 CFR 51.1009. The result of this
process was Alaska's adoption and implementation of a control strategy
that includes the identified technologically and economically feasible
control measures for sources in the FNSB NAA. The EPA proposes to find
that the FNSB Moderate Plan provides for the implementation of RACM/
RACT as required by CAA sections 189(a)(1)(C) and 172(c)(1), and
additional reasonable measures as required by CAA sections 172(c)(6)
and 40 CFR 51.1009. The EPA's evaluation of the FNSB Moderate Plan
indicates that the control strategy includes permanent and enforceable
requirements on the appropriate sources at the relevant time of year
(i.e. during wintertime stagnant air episodes) and takes appropriate
credit for emissions reductions from the suite of control measures.
a. The EPA's Evaluation and Proposed Action: Non-Point/Area Sources--
RACM/RACT
    As explained previously, Alaska's initial SIP submission cited a
citizen's referendum as a basis for not adopting and implementing many
of the control measures analyzed. The referendum, in place from 2010 to
2014, limited the Borough's authority to regulate home heating sources
in any manner, thereby effectively preventing the local government from
controlling emissions from the critical heating source category.\16\
The EPA does not consider social acceptability to be an appropriate
basis for rejecting required emission control measures, but the
capability of effective implementation and enforcement are relevant
considerations. See 81 FR 58041. Therefore, the EPA does not view the
referendum to be a valid basis for asserting that a control measure is
unreasonable, whether for social, economic or technical reasons.
---------------------------------------------------------------------------

    \16\ FNSB Code 8.21.025 ``The borough shall not, in any way,
regulate, prohibit, curtail, nor issue fines or fees associated
with, the sale, distribution, or operation of heating appliances or
any type of combustible fuel.''
---------------------------------------------------------------------------

    However, in October 2014, the referendum expired and Alaska began
the process of adopting more stringent controls for the FNSB NAA,
including control measures applicable to residential heating sources
that are a major contributor to violations of the 2006 24-hour
PM2.5 NAAQS in this nonattainment area. Due to the timing of
the expiration of the referendum, it was not possible for the Borough
to enact these measures, and for Alaska to submit the measures for
inclusion into the attainment plan, by the December 31, 2014 deadline
for Moderate area attainment plans. In February 2015, the Borough
enacted its mandatory curtailment program and other measures and Alaska
adopted the measures in the SIP and submitted them for EPA review in a
November 22, 2016 supplementary submission. The EPA supports ongoing
state efforts to improve attainment plan control strategies and
therefore believes it is appropriate to consider the entirety of
adopted control measures for the FNSB NAA submitted for the EPA's
review, notwithstanding the timing of the submission.
    The control strategy in the FNSB Moderate Plan includes a number of
control measures targeted at reducing residential wood heating
emissions during the winter months when exceedances of the NAAQS
typically occur. The control measures, including the wintertime open
burning prohibition, dry wood requirement, visible emissions limit of
20 percent opacity, prohibited fuel sources, and mandatory curtailment
program are similar to approved control programs adopted in other
nonattainment areas impacted by emissions from residential wood heating
sources. In addition, the FNSB Moderate plan includes emissions
standards for wood stoves and hydronic heaters that are more stringent
than the current EPA emissions standards for these devices. See 40 CFR
part 60, subparts AAA and QQQQ. For example, Alaska adopted an
emissions standard of 2.5 grams per hour for wood stoves, which is more
stringent than the emissions standard of 4.5 grams per hour for Step 1
EPA-certified wood stoves. Also, the Borough's emissions standards
apply to coal-fired heaters, which the EPA does not regulate. See 80 FR
13676, March 16, 2015. The control strategy includes a provision that

excludes owners of newly constructed buildings from obtaining a ``no
other adequate source of heat'' determination, which encourages
installation of alternative heating sources in new buildings so that
the building occupants may comply with curtailments. These control
measures are beyond what is typically found in other nonattainment
areas impacted by wood heating sources but were appropriate for
inclusion as RACM/RACT in the FNSB Moderate Plan. Because of the
specific facts and circumstances of FNSB NAA, and the severity of the
nonattainment problem in this area, Alaska is appropriately focusing
multiple control measures on this important source category.
    Alaska did not specifically analyze area source controls for
NH3. The EPA agrees with Alaska's decision to exclude
NH3 area source controls from its analysis. The EPA is
unaware of any available technologies to control NH3
emissions from combustion sources where ammonia is emitted as a product
of combustion (other than improved combustion conditions such as those
achieved via wood stove changeout). Although the control strategy
primarily focuses on reducing direct PM2.5 emissions, it
also provides for emissions reductions for some PM2.5
precursors. For example, NH3 emissions from wood heating
were estimated to be 13 percent lower in the 2015 inventory than in
2008 base year inventory.
    As noted, the control strategy focuses on reducing emissions from
residential wood heating sources and includes control measures such as
a woodstove changeout program, a requirement to use only dry wood, a
mandatory curtailment program, and an opacity limit for residential
heating sources. The EPA agrees that these control measures
appropriately target the emissions contributing to nonattainment and
provide for reductions during winter stagnation events when
concentrations of emissions build-up and lead to exceedances of the
2006 24-hour PM2.5 NAAQS.
    As discussed in section II.C.2.a of this proposal, the mandatory
curtailment control program has two stages, with ambient
PM2.5 trigger levels at 35 [mu]g/m\3\, referred to as a
stage 2 alert, and 55 [mu]g/m\3\, referred to as a stage 3 alert.
During a stage 2 alert, the only solid-fuel fired heaters that can be
operated are U.S. EPA certified devices, EPA Phase II hydronic heaters
with PM2.5 annual average emissions ratings of 2.5 grams per
hour or less, masonry heaters, pellet stoves, and fireplaces. During a
stage 3 alert, the use of solid-fuel heaters, masonry heaters, pellet-
fueled appliances, cook stoves, fireplaces, and waste oil devices is
prohibited. The EPA believes that the two-stage alert system meets
RACM/RACT level control requirements for this source category for the
FNSB NAA. The EPA notes that the mandatory curtailment program includes
applicability limitations during stage 3 alerts (no other adequate
source of heat, power outage, and ambient temperatures below -15
[deg]F). We have reviewed Alaska's mandatory curtailment program which
operates in conjunction with the other control measures that apply to,
and reduce emissions from, the same sources, including a 20 percent
limit on opacity and a requirement that only dry wood (with a moisture
content of 20 percent or less) be burned at all times. We believe the
suite of control measures provides for continuous control of this
source category, consistent with CAA requirements. We have also
considered that many mandatory curtailment programs in other
nonattainment areas contain limitations on applicability when there is
no other adequate source of heat that are based on considerations of
public welfare. The EPA concludes that in the FNSB NAA, where
wintertime temperatures can be extreme and there is limited
availability of fuel alternatives such as natural gas, the three
limitations in Alaska's mandatory curtailment program similarly invoke
public welfare considerations that are appropriate in the context of a
Moderate area plan. Additionally, the FNSB NAA is relatively new to
programs for reducing emissions from wood heating and, prior to 2015,
the community had not experienced mandatory curtailments. The two-stage
mandatory curtailment program is therefore appropriately suited for the
FNSB NAA in that it provides for implementation of a curtailment
program that will reduce emissions in a manner that can facilitate
program adoption and implementation by the community. We also note that
if the FNSB NAA is reclassified to Serious for failure to attain the
2006 PM2.5 NAAQS, as proposed (81 FR 91088, December 16,
2016), Alaska will need to reevaluate and strengthen its SIP control
strategy to meet the more stringent Serious area requirement for BACM.
    We have reviewed Alaska's determination in the FNSB Moderate Plan
that its area source control measures represent the adoption of
reasonable control measures that meet RACM requirements and we believe
that Alaska adequately justified its conclusions with respect to each
of these measures. As noted, the EPA proposed to reclassify the FNSB
NAA to Serious for failure to attain the PM2.5 NAAQS by the
December 31, 2015 attainment date. Id. If the reclassification is
finalized, Alaska will need to reevaluate and strengthen its attainment
plan control strategy for the PM2.5 NAAQS as necessary to
meet the more stringent Serious area requirement for BACM and BACT,
among other requirements.
b. The EPA's Evaluation and Proposed Action: Stationary Point Sources--
RACM/RACT
    Alaska's RACM/RACT analysis for the six major stationary sources
located in the FNSB NAA appropriately focused on PM2.5,
SO2 and NH3. The EPA agrees with the selection of
fabric filters (baghouses) as meeting RACM/RACT-level controls for
direct PM2.5 emissions. This control technology is well
established as meeting RACM/RACT for this application. In the FNSB NAA,
NH3 accounts for less than 0.001 tons per day of emissions
in the FNSB NAA. Alaska's RACM/RACT analysis did not identify any
control technologies for NH3 and the EPA is unaware of any
available technologies to control emissions of NH3 from
combustion sources where the ammonia is solely a product of combustion.
The EPA therefore agrees with Alaska's decision with respect to
stationary source controls for NH3.
    With respect to SO2, Alaska identified a suite of
controls that could potentially be implemented at the stationary
sources in the FNSB NAA and conducted a cost analysis to determine the
capital costs and cost effectiveness of the controls to conclude that
SO2 controls were not economically feasible. The EPA
understands that, due to the fact that the FNSB Moderate Plan
demonstrated the impracticability of attaining the 2006
PM2.5 NAAQS by the end of 2015 and the expectation that the
area will be reclassified from Moderate to Serious, Alaska has started
working on a BACM and BACT analysis for stationary sources to
strengthen its SIP control strategy to meet the more stringent Serious
area requirements. Alaska conducted its RACM/RACT analysis for
stationary sources with the expectation that it would need to prepare a
Serious area nonattainment plan and therefore presupposing that a BACM/
BACT analysis would also be required in the near future.\17\
Accordingly, Alaska's conclusion that additional SO2
emissions controls for these stationary sources were not economically
feasible for purposes of

meeting RACM/RACT requirements will be revisited in the context of
Alaska's BACM/BACT analysis.
---------------------------------------------------------------------------

    \17\ The EPA has acknowledged that it is appropriate for a state
to consider implementing RACM/RACT in a way that supports addressing
BACM/BACT. 81 FR 58045.
---------------------------------------------------------------------------

    We have reviewed Alaska's determination in the FNSB Moderate Plan
that its stationary source control measures represent the adoption of
reasonable control measures that meet RACM/RACT requirements and we
believe that Alaska adequately justified its conclusions with respect
to each of these measures.
    As discussed previously, the EPA has proposed to reclassify the
FNSB NAA to Serious for failure to attain the PM2.5 NAAQS by
the December 31, 2015 attainment date (81 FR 91088). Alaska will need
to reevaluate and strengthen its attainment plan control strategy for
the PM2.5 NAAQS as necessary to meet the more stringent
Serious area requirement for BACM and BACT, among other requirements.

D. Air Quality Modeling

1. Requirements for Air Quality Modeling
    CAA section 189(a)(1)(B) requires each state with a Moderate
nonattainment area to submit a plan that includes, among other things,
either (i) a demonstration (including air quality modeling) that the
plan will provide for attainment by the applicable attainment date; or
(ii) a demonstration that attainment by such date is impracticable. For
model attainment demonstrations, the EPA's modeling requirements are in
40 CFR part 51, appendix W (82 FR 5182, January 17, 2017). The EPA's
guidance recommendations for model input preparation, model performance
evaluation, use of the model output for the attainment demonstration,
and modeling documentation are described in Draft Guidance for
Demonstrating Attainment of Air Quality Goals for Ozone,
PM2.5, and Regional Haze (Modeling Guidance).\18\ The EPA
recommends that states prepare modeling protocols as part of their
modeled attainment demonstrations. The Modeling Guidance describes the
topics states should address in this modeling protocol. A modeling
protocol should detail and formalize the procedures for conducting all
phases of the modeling analysis, such as describing the background and
objectives, creating a schedule and organizational structure,
developing the input data, conducting model performance evaluations,
interpreting modeling results, describing procedures for using the
model to demonstrate whether proposed strategies are sufficient to
attain the applicable standard, and producing documentation to be
submitted for EPA Regional Office review and approval prior to actual
modeling.
---------------------------------------------------------------------------

    \18\ The Modeling Guidance is available on the EPA's SCRAM Web
site, Web page: http://www.epa.gov/scram001/guidance_sip.htm; direct
link: https://www3.epa.gov/scram001/guidance/guide/Draft_O3-PM-RH_Modeling_Guidance-2014.pdf.
---------------------------------------------------------------------------

    Air quality modeling is used to establish emissions targets, the
combination of emissions of PM2.5 and PM2.5
precursors that the area can accommodate and still attain the standard,
and to assess whether the proposed control strategy is likely to result
in attainment of the relevant NAAQS. Air quality modeling is performed
for representative episodes in the past and compared to air quality
monitoring data collected during those episodes in order to determine
model performance. To project future design values, the model response
to emission reductions, in the form of relative response factors, is
applied on a chemical species-by-species basis to the baseline design
value, as implemented in the SMAT methodology and described in the
Modeling Guidance.
    In addition to a modeled attainment demonstration that focuses on
locations with an air quality monitor, the 2016 PM2.5
Implementation Rule recommends an unmonitored area analysis. This
analysis is intended to ensure that a control strategy leads to
reductions in PM2.5 at other locations that have no monitor
but might have base year and/or projected future year ambient
PM2.5 levels exceeding the standard. This is particularly
critical where the state and/or the EPA has reason to believe that
potential violations may be occurring in unmonitored areas. An
unmonitored area analysis is of lesser value in the case of an
impracticability demonstration that shows an area will not attain the
standard at monitored locations. Finally, as discussed in the Modeling
Guidance, the EPA recommends supplemental air quality analyses. These
are used as part of a weight of evidence analysis, in which the
likelihood of attainment is assessed by considering evidence other than
the main air quality modeling attainment test.
    The EPA has not issued modeling guidance specific to
impracticability demonstrations, but believes that a state seeking to
make such a demonstration, generally, should provide air quality
modeling similar to that required for an attainment demonstration. The
main difference between an attainment demonstration and an
impracticability demonstration is that despite the implementation of a
control strategy including RACM/RACT and additional reasonable
measures, an impracticability demonstration does not demonstrate
attainment of the standard by the statutory Moderate area attainment
date. Alternatively, a model projection could show that the
implementation of the SIP control strategy results in attainment of the
standard after the statutory Moderate area attainment date. However,
there are cases where modeling may not be needed to demonstrate that it
is impracticable to attain by the statutory Moderate area attainment
date and the EPA has therefore determined that modeling is not a
regulatory requirement to support an impracticability demonstration. 40
CFR 51.1009(a)(4); 81 FR 58048. For an attainment demonstration, a
thorough review of all modeling inputs and assumptions is especially
important because the modeling must ultimately support a conclusion
that the plan (including its control strategy) will provide for timely
attainment of the applicable NAAQS.
    In contrast, for an impracticability demonstration, if the state
and the EPA determine that the area cannot attain the NAAQS by the
latest statutory Moderate area attainment date, the result is that the
EPA will reclassify the area from a Moderate nonattainment area to a
Serious nonattainment area. This reclassification obligates the state
to submit a new attainment plan that meets more stringent regulatory
requirements (e.g. BACM and BACT level emission controls on sources in
the area) and the requirement for a Serious area attainment
demonstration that will necessarily need to include air quality
modeling that demonstrates attainment by the applicable attainment
date. Thus, the Serious area planning process would provide an
opportunity to refine the modeling analysis and/or correct any
technical shortcomings in the impracticability demonstration.
2. Air Quality Modeling in the FNSB Moderate Plan and the EPA's
Evaluation
    In FNSB Moderate Plan section III.D.5.8 and appendix III.D.5.8,
Alaska provided air quality modeling to support its demonstration that
it was impracticable for the FNSB NAA to attain the 2006 24-hour
PM2.5 NAAQS by the statutory Moderate area attainment date
of December 31, 2015. The modeling demonstration uses three-dimensional
grid-based meteorological modeling and full photochemical grid
modeling, combined with speciated monitoring data from 2006-2010 from

the State Office Building site in Fairbanks, to assess attainment.
Alaska used the CMAQ photochemical model version 4.7.1, the most
current version of the model at the time Alaska developed modeling for
the FNSB Moderate Plan. Alaska examined subsequent versions of CMAQ but
did not upgrade model versions because the newer versions did not
include significant scientific improvements relevant for the FNSB NAA.
The Weather Research Forecasting Model (model version 3.1) was used to
prepare meteorological input for CMAQ. The Sparse Matrix Operator
Kernal Emissions (SMOKE) processor was used to create photochemical
transport model inputs. Emissions inventory estimates were combined
with meteorological inputs developed for the two multiday air quality
episodes of elevated PM2.5 concentrations (January 23-
February 10, 2008; and November 2-17, 2008) and with the available
chemistry mechanisms in CMAQ to assess the ability of the FNSB NAA to
demonstrate attainment in 2015.
    To calculate the projected 2015 PM2.5 design value,
Alaska performed the SMAT methodology. Alaska used the ratio of future
year (2015) to base year (2008) modeling results to derive relative
response factors for each chemical species and these response factors
were applied on a chemical species-by-species basis to the baseline
design value. The concentrations of chemical species used in the
baseline design value was an average of the monitoring data for the top
25 percent most polluted wintertime days (in the first and fourth
quarters) of the years 2006-2010. Only the top 25 percent was used
because there are many cleaner days when the emission source mix and
contributions of PM2.5 to the monitor are not relevant for
air quality planning to meet the 24-hour PM2.5 standard. The
top 25 percent most polluted wintertime days captured the days with
weather conditions and emissions patterns that occur when the standard
is exceeded. The average of the speciated concentrations on the top 25
percent most polluted days were weighted to the observed
PM2.5 concentrations from the official regulatory data at
the State Office Building, such that the speciated PM2.5
data used for air quality modeling (and for the precursor
demonstration) are reflective of the baseline design value of 44.7
[mu]g/m\3\. The technique was not used for the second and third
quarters because an examination of the PM2.5 data from the
baseline period 2006-2010 showed that the all high monitored values
from those quarters had been flagged as exceptional events and
submitted to the EPA for concurrence. Therefore, second and third
quarter monitoring data has no influence on the FNSB 24-hour
PM2.5 NAAQS design values.
    Alaska evaluated the results of their CMAQ modeling with observed
PM2.5 mass and speciated PM2.5 mass from the
monitor at the State Office Building. The base year modeling for the
two multiday episodes of 2008 used hourly meteorology and emissions
specific to those episodes and are Alaska's best attempt at reproducing
air quality during the two wintertime pollution episodes. Alaska
selected generally accepted techniques for assessing model performance,
such as goal and criteria thresholds from academic literature and past
attainment modeling done by other areas. Criteria are metrics for when
the modeling can be considered generally acceptable, and goals are
metrics for when the modeling can be considered to be performing well.
After comparing model performance to the selected techniques, Alaska
concluded that the model meets modeling goals for total
PM2.5 and meets criteria for organic carbon, elemental
carbon, and nitrate. In contrast, modeled estimates of the sulfate,
ammonium, and other PM2.5 components of PM2.5
mass were underpredicted. Alaska explained that the large
underprediction of sulfate is likely due to the fact that the CMAQ
existing sulfate chemistry mechanisms are intended for locations with
liquid water clouds, warmer temperatures, and more sunlight. Alaska
notes that the underprediction of ammonium is very likely a by-product
of the sulfate underprediction. Thus, Alaska believes that
NH3 controls or NOX controls would likely still
be accurately reflected in the modeling results irrespective of the
large underprediction of sulfate.
    In light of acceptable model performance for PM2.5
overall and for certain chemical species, Alaska used CMAQ to test
control strategies on primary PM2.5, NOX, and
NH3. The sulfate component of PM2.5 was
considered to stay constant in future years because, for the reasons
explained above, the modeling system was not considered adequate to
assess SO2 controls. As weight of evidence, Alaska presented
a sensitivity study in which in which the changes in SO2
emissions from the control strategy are used to estimate changes in
sulfate. For the purposes of the sensitivity study, Alaska assumed that
sources of SO2 are responsible for sulfate in proportion to
their share of the SO2 inventory. Because the control
strategy shifts home heating fuel from relatively sulfur-poor wood to
relatively sulfur-rich oil, the 2015 PM2.5 design value in
this analysis would increase by 0.5 [mu]g/m\3\. This is a relatively
small increase in PM2.5 compared to the projected decrease
in PM2.5 from the control strategy of 6.9 [mu]g/m\3\.
    The FNSB Moderate Plan section III.D.5.8 also contains an
unmonitored area analysis and a weight of evidence analysis as
additional support for the modeling demonstration. Alaska used various
analytical techniques to inform modeling decisions and to assess model
performance. Statistical evaluations with positive matrix factorization
and chemical mass balance modeling were used to attribute and
prioritize source significance. To understand the distribution of
emissions from wood burning versus fossil fuels, a Carbon-14 analysis
was used to determine the age distribution of carbon molecules found at
each monitoring site. Levoglucosan, an organic compound that is
considered to be a tracer of biomass burning, was analyzed to assess
the significance of wood burning. A dispersion modeling study using the
CALPUFF model was used to characterize PM2.5 contribution
from permitted stationary sources to the State Office Building monitor.
    The weight of evidence analysis consistently attributed more than
50 percent of the PM2.5 at the State Office Building monitor
to wood smoke. Stationary sources are estimated to contribute 5 percent
of the measured PM2.5 at the State Office Building monitor
based on emissions of direct PM2.5 alone, and potentially
another 15 percent if all of the sulfate at the monitor could be
attributed to stationary sources rather than split with residential oil
heat. In contrast, Alaska's emission inventory reports that stationary
sources make up 29 percent of the emissions of direct PM2.5.
The large difference between the proportion of direct PM2.5
emissions from stationary sources and their modeled contribution at the
State Office Building monitor is primarily due to the influence of the
stable atmosphere near the surface, and secondarily because prevailing
winds at the top of the stacks do not carry plumes of many of the
stationary sources in the direction of the monitor. This shows the
value of using modeling and source apportionment techniques, as
compared to emissions inventory information alone, in assessing the
source of PM2.5 air pollution in the nonattainment area.
    Based on the unmonitored area analysis, Alaska projects 2015 design
values above the standard in several parts of the FNSB NAA, including
the western part of downtown Fairbanks, to the southeast of downtown
Fairbanks,

and in the North Pole area. This modeling suggests there are locations
other than the State Office Building location where exceedances may be
occurring. Alaska should design any Serious area plan in order to
address such potential exceedances in the FNSB NAA.
3. The EPA's Conclusions on Air Quality Modeling
    The EPA is proposing to find that Alaska's model is adequate for
assessing whether the FNSB NAA will attain the PM2.5 NAAQS
by the statutory Moderate area attainment date, i.e., by December 31,
2015, in the context of this SIP submission. The model inputs, episode
selection, performance evaluation, extensive supplemental information,
and attainment test methodology are well-described and conform with the
state-of-the art for air quality modeling. Alaska found unacceptable
model performance for some PM2.5 chemical species, but the
control strategy did not rely on controls of those chemical components.
The EPA therefore proposes to find that the modeling is also adequate
for purposes of supporting the control strategy analysis, RFP, and
impracticability demonstrations.
    As discussed previously, the EPA notes that because the FNSB NAA
did not attain the 2006 24-hour PM2.5 NAAQS by December 31,
2015, Alaska will be required to submit a Serious area SIP by December
31, 2017. In a separate action, the EPA has recently proposed to find
that the area failed to attain and thus will be reclassified from
Moderate to Serious if the Agency finalizes that proposal. The EPA
expects Alaska to further analyze modeling gaps related to sulfate for
the Serious area plan. In addition, the EPA believes that the
heterogeneity of wood smoke emissions and lack of air movement during
polluted episodes, will continue to make an unmonitored area analysis
an important component in the Serious area plan.

E. Demonstration That Attainment by the Moderate Area Attainment Date
Is Impracticable

1. Requirements for Attainment/Impracticability of Attainment
Demonstrations
    CAA section 189(a)(1)(B) requires that each Moderate area
attainment plan include a demonstration that the plan provides for
attainment by the latest applicable Moderate area deadline or,
alternatively, that attainment by the latest applicable attainment date
is impracticable. A demonstration that the plan provides for attainment
must be based on air quality modeling, and the EPA generally recommends
that a demonstration of impracticability also be based on air quality
modeling and be consistent with the EPA's modeling regulations and
guidance (51.1011(a)(2); 51.1011(a)(4)(ii); and 81 FR 58049).
    CAA section 188(c) states, in relevant part, that the Moderate area
attainment date ``shall be as expeditiously as practicable but no later
than the end of the sixth calendar year after the area's designation as
nonattainment.'' For the 2006 24-hour PM2.5 NAAQS, effective
December 14, 2009, the applicable Moderate area attainment date under
section 188(c) for the FNSB NAA is as expeditiously as practicable, but
no later than December 31, 2015. In SIP submissions to demonstrate
impracticability, the state should document that its required control
strategy in the plan represents the application of RACM/RACT to
existing sources. Moderate areas that do not demonstrate timely
attainment should adopt all reasonable control measures (i.e., those
measures that are technologically and economically feasible). 81 FR
58035. The impracticability demonstration should be a showing that the
area cannot attain by the applicable date, notwithstanding
implementation of all reasonable controls in the Moderate area
attainment plan. 81 FR 58045.
2. Impracticability Demonstration in the FNSB Moderate Plan
    The FNSB Moderate Plan includes a demonstration, based on air
quality modeling and additional supporting analyses discussed in
section II.D of this proposal, that attainment by the statutory
Moderate area attainment date of December 31, 2015 was impracticable.
Implementation of the selected control strategy resulted in a projected
2015 design value of 39.6 [micro]mu;g/m\3\ at the State Office
Building, and Alaska's unmonitored area analysis shows that several
other parts of the FNSB NAA may also violate the NAAQS in 2015. On
November 22, 2016, and January 6, 2017, Alaska submitted a SIP revision
supported by additional clarifying information that included the
adoption of control measures that have been implemented since the
initial submission of the FNSB Moderate Plan in December 2014. The
control measures include a mandatory curtailment program for solid-fuel
fired heaters, a requirement to use dry wood in wood-fired heaters, an
opacity limit applicable to solid-fuel fired heating devices, and other
measures that strengthened the overall control strategy. In the 2017
Clarification, Alaska provided a demonstration that included the
additional emissions reductions from these control measures, which
resulted in a projected 2015 future year design value of 37.8
[micro]mu;g/m\3\. Accordingly, Alaska demonstrated that attainment by
the statutory Moderate area attainment date would still have been
impracticable even if all control measures had been adopted earlier.
3. The EPA's Evaluation and Proposed Action: Impracticability
Demonstration
    We have evaluated the FNSB Moderate Plan's demonstration that it
was impracticable for the area for attain by the December 31, 2015
statutory Moderate area attainment date, supporting air quality
modeling, and control strategy analyses addressing the adoption of all
reasonable measures. We are proposing to approve Alaska's demonstration
that it was not practicable for the area to attain the 2006 NAAQS
standard by December 31, 2015.
    In addition to the information in the FNSB Moderate Plan and
supplement, we have reviewed recent PM2.5 monitoring data
from the FNSB NAA. The data show that the area did not attain the
PM2.5 NAAQS by the December 31, 2015 attainment date. The
State Office Building monitor, which is the original violating monitor
in the FNSB NAA and was the basis of the FNSB Moderate Plan, had a
2013-2015 design value of 43 [micro]mu;g/m\3\.\19\ In addition, the
monitor at the North Pole Fire Station became a regulatory monitor in
2015, after Alaska's development and submission of the initial FNSB
Moderate Plan. The North Pole Fire Station monitor has a 2013-2015
design value of 124 [micro]mu;g/m\3\. The EPA has therefore separately
proposed to find that the FNSB NAA did not attain by the statutory
Moderate area attainment date and reclassify the area from Moderate to
Serious pursuant to CAA section 188(b)(2) (81 FR 91088, December 16,
2016). If the EPA finalizes the reclassification of the FNSB NAA from
Moderate to Serious, Alaska will be required to submit a Serious area
attainment plan by December 31, 2017. Because the North Pole Fire
Station monitor is now a regulatory monitor in the FNSB NAA, Alaska and
the EPA will address it in the development of the Serious area plan for
the FNSB NAA.
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    \19\ The 2013-2015 design value excludes exceedances during
summer months that were identified as wildfire exceptional events
and the EPA has approved excluding the data. (See section II.I of
this proposal.)

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F. Reasonable Further Progress and Quantitative Milestones

1. Requirements for RFP and QMs
    CAA section 172(c)(2) requires nonattainment area plans to provide
for RFP. In addition, CAA section 189(c) requires PM2.5
nonattainment area SIPs to include QMs to be achieved every 3 years
until the area is redesignated to attainment and which demonstrate RFP.
CAA section 171(1) defines RFP as ``such annual incremental reductions
in emissions of the relevant air pollutant as are required by [Part D]
or may reasonably be required by the Administrator for the purpose of
ensuring attainment of the applicable [NAAQS] by the applicable date.''
Neither subpart 1 nor subpart 4 require that a set percentage of
emissions reductions be achieved in any given year for purposes of
satisfying the RFP requirement for PM2.5 NAAQS.
    The EPA has historically interpreted the requirement to be met by a
state showing annual incremental emission reductions in its attainment
plan sufficient to maintain generally linear progress toward attainment
by the applicable deadline. 40 CFR 51.1012(a)(4); see also 59 FR 41998,
42015 (August 10, 1994). In some circumstances, the EPA has
acknowledged that RFP may be better represented as step-wise progress
as controls are implemented and achieve significant reductions over a
relatively short period. The EPA's recent implementation rule for the
PM2.5 NAAQS has reiterated these requirements. An attainment
plan for a PM2.5 nonattainment area must include an RFP
analysis that demonstrates that sources in the area will achieve such
annual incremental reductions in emissions of direct PM2.5
and PM2.5 plan precursors as are necessary to ensure
attainment as expeditiously as practicable. 40 CFR 51.1012(a). The RFP
analysis must include a schedule for implementation of the control
measures and provide projected emissions from these measures for each
applicable milestone year. Id. at 51.1012(a)(1)-(2). At the state's
election, the RFP analysis may also identify ambient air quality
targets for the milestone years at the design value monitor locations.
Id. at 51.1012(a)(5).
    Section 189(c) provides that attainment plans must include QMs that
will be used to measure RFP every 3 years until redesignation. Thus,
the EPA determines an area's compliance with RFP in conjunction with
determining its compliance with the QM requirement. 40 CFR 51.1013(a)
(requiring attainment plans to include specific QMs that will
demonstrate RFP toward attainment). Because RFP is an annual emission
reduction requirement and the QMs are to be achieved every 3 years,
when a state demonstrates compliance with the QM requirement, it
provides an objective evaluation of RFP that has been achieved during
each of the relevant 3 years. Id. at 51.1013(a)(1)(ii). The EPA has
historically interpreted the CAA to authorize a broad variety of QMs,
so long as they provide a way to verify compliance with the RFP
requirement. QMs are not required to take any particular form but they
should consist of elements that allow progress to be quantified or
measured objectively. 81 FR 58064. However, at a minimum, QMs for a
Moderate area attainment plan must track progress in implementing
control measures by each milestone date. Therefore, timely
implementation of control measures comprising the RFP plan provides a
means for satisfying the QM requirement. Id. The Act requires states to
include RFP and QMs in attainment plans for all Moderate areas, even
for areas that cannot practicably attain by the attainment date.
    The CAA does not specify the starting point for counting the 3-year
periods for QMs under CAA section 189(c). However, the EPA's
longstanding interpretation of the CAA is that the first QM should fall
3 years after the latest date on which the state should have submitted
the attainment plan. For the 2006 PM2.5 NAAQS, the EPA set
QMs to be achieved no later than the 3 years after December 31, 2014,
and every 3 years thereafter until the QM date falls within 3 years
after the applicable attainment date. 40 CFR 51.1013(a)(4).
Accordingly, the first QM date for the FNSB NAA must be met no later
than December 31, 2017 (3 years after December 31, 2014). Following
reclassification of the FNSB NAA to Serious with a new applicable
attainment date of December 31, 2019, the later QM of December 31, 2020
will apply, with additional QMs every 3 years thereafter as may be
necessary for the Serious area plan in light of any extension of the
applicable attainment date.
    A state must submit a QM report to the EPA no later than 90 days
after the QM date. 40 CFR 51.1013(b). The QM reports must contain: (1)
A certification that the attainment plan control strategy is being
implemented, (2) technical support to demonstrate that the QMs have
been satisfied and how the emissions reductions achieved to date
compare to those scheduled to meet RFP, (3) a discussion of whether the
area will attain the 2006 PM2.5 NAAQS by the projected
attainment date.
2. RFP and QMs in the FNSB Moderate Plan
    The RFP demonstration in the FNSB Moderate Plan addresses emissions
of direct PM2.5, NOX, SO2, and
NH3 and includes a projected emissions inventory for the
2017 QMs based on implementing the control strategy (see the FNSB
Moderate Plan sections III.D.5.6 and III.D.5.8, the 2017 Clarification,
and table 6 in section II.C, above). Alaska assessed the emissions
reductions that would be achieved from the base year emissions
inventory by 2017 from the control measures included in the control
strategy. To determine whether the 2017 emissions projections were
consistent with generally linear progress towards attainment, Alaska
interpolated linearly between the 2015 projected emissions inventory
for the FNSB NAA and the 2019 inventory that Alaska based on projected
attainment for the FNSB NAA by that year, i.e., the tenth year
following designation. The table below summarizes the 2017 QMs and RFP
demonstration in the FNSB Moderate Plan.

                                   Table 7--FNSB NAA RFP Demonstration and QMs
                                                 [Tons per day]
----------------------------------------------------------------------------------------------------------------
              Emissions projections                    PM2.5            NOX             SO2             NH3
----------------------------------------------------------------------------------------------------------------
2017 Linear Progress QMs........................            3.96           18.97           13.00           0.200
2017 Projected Emissions........................            3.91           18.95           12.41           0.188
----------------------------------------------------------------------------------------------------------------

    Alaska included an inventory for 2017 and motor vehicle emissions
budgets, which are discussed in section II.H below. The RFP analysis is
based on winter episode average-season-day emissions for the FNSB NAA
and actual

emissions for stationary point sources. The RFP analysis projected that
emissions of direct PM2.5 and NOX would decline
from 2015 to 2017. The SO2 and NH3 emissions were
projected to slightly increase, due in large part to implementation of
the control strategy which places greater reliance on gas and oil
heating in place of wood and other solid fuels to reduce overall
emissions and concentrations of PM2.5 in the FNSB NAA. The
EPA has acknowledged that in some circumstances a state could meet the
RFP requirement even when emissions of one or more plan precursors are
not decreasing, provided that the relative air quality impacts of the
emissions reductions of direct PM2.5 and aggregate
PM2.5 plan precursors have generally linear reductions
towards what is needed for expeditious attainment in the area. In such
a circumstance the state would demonstrate that even when one or more
plan precursor is not decreasing, the emissions reductions of direct
PM2.5 and remaining PM2.5 plan precursors are the
dominant factors in reducing ambient PM2.5 concentrations
and therefore adequate to demonstrate RFP. 81 FR 58057. Alaska's RFP
analysis projected that implementation of the control strategy would
decrease emissions of direct PM2.5 and NOX and
slightly increase emissions of SO2 and NH3
emissions, with aggregate emissions reductions of direct
PM2.5 and all precursors lower than linear progress.
    As previously noted, on November 22, 2016, and January 6, 2017,
Alaska provided a supplementary submission and clarifying information
to the EPA that included implementation of control measures for area
sources in 2015. The control measures include a mandatory curtailment
program for solid-fuel heaters, a requirement to use only dry wood in
wood heaters, an opacity limit for solid-fuel fired heating devices,
and other measures that strengthened the control strategy. Alaska
updated the RFP analysis to include the implementation of these new
measures.
3. The EPA's Evaluation and Proposed Action: RFP and QMs
    The FNSB Moderate Plan, including the 2016 supplement and 2017
Clarification, demonstrates that the control strategy, including all
reasonable controls, has been implemented and identifies projected
emissions levels, in a 2017 emissions inventory, that reflect full
implementation of the control strategy for the area. In an area that
cannot practicably attain the PM2.5 NAAQS by the applicable
Moderate area attainment date, we believe it is reasonable to find that
full implementation of a control strategy that satisfies the Moderate
area control requirements (RACM/RACT and additional reasonable
measures) represents RFP toward attainment. We propose, therefore, to
approve the RFP demonstration for direct PM2.5,
NOX, SO2, and NH3 as meeting the
requirements of CAA section 172(c)(2).
    In evaluating whether the submitted attainment plan meets the RFP
and related QM requirements, we are relying in part on the FNSB
Moderate Plan's analysis of the implementation of control measures
adopted before 2015 and more recently in 2016. As previously noted, if
the FNSB NAA is reclassified from a Moderate to Serious nonattainment
area, as proposed, the area will be subject to Serious area plan
requirements and Alaska will need to reevaluate and strengthen its
attainment plan control strategy, and provide a new attainment
demonstration and revised RFP demonstration and QMs based on the
Serious area control strategy.
    The EPA proposes to approve the FNSB Moderate Plan as meeting both
the RFP and QM requirements. The FNSB Moderate Plan provides sufficient
data and analyses that demonstrate emissions reductions that provide
RFP toward attainment in 2017, and the QM for 2017 provides an
objective way for the EPA to verify that Alaska has met the RFP
requirements for the relevant 3 years of the attainment plan for this
area.
    On January 6, 2017, Alaska submitted a QM report (2017 QM Report)
to the EPA certifying that the 2017 QMs for the FNSB NAA have been
achieved.\20\ The EPA has evaluated the 2017 QM Report and determines
that, it adequately meets the requirements of 40 CFR 51.1013(b). The
2017 QM Report includes a certification from the Governor's designee
and an appropriate demonstration that the control strategy has been
fully implemented and that the emissions reductions achieved are
consistent with the 2017 QMs that demonstrate RFP at the State Office
Building monitor. In the 2017 QM Report, Alaska acknowledges that,
consistent with the impracticability demonstration in the FNSB Moderate
Plan, the FNSB NAA did not attain the PM2.5 NAAQS by the
moderate area attainment date of December 31, 2015. Based on our review
of Alaska's 2017 QM Report, the EPA agrees that the FNSB NAA has
achieved the RFP emissions goals and the 2017 QMs in the FNSB Moderate
Plan for direct PM2.5, NOX, SO2, and
NH3.
---------------------------------------------------------------------------

    \20\ Alaska's 2017 quantitative milestone report is available in
the docket for this action.
---------------------------------------------------------------------------

G. Contingency Measures

1. Requirements for Contingency Measures
    Under CAA section 172(c)(9), PM2.5 plans must include
contingency measures to be implemented if an area fails to meet RFP or
fails to attain the PM2.5 standards by the applicable
attainment date. Under subpart 4, however, the EPA interprets section
172(c)(9) in light of the specific requirements for particulate matter
nonattainment areas. CAA section 189(b)(1)(A) differentiates between
Moderate area attainment plans that provide for timely attainment by no
later than the sixth calendar year after designation and those that
demonstrate that attainment by that date is impracticable. Where the
SIP submission includes a demonstration that attainment by the
applicable attainment date is impracticable, the EPA interprets CAA
section 172(c)(9) not to require contingency measures that would take
effect upon failure to attain. 81 FR 58067. In an attainment plan
submission that meets the impracticability demonstration requirement,
the state need only submit contingency measures to be implemented if a
state fails to meet any RFP requirement of the plan, any QM in the
plan, or to submit a QM report, as provided in 40 CFR 51.1014(a)(1)-
(3).\21\
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    \21\ The EPA does not interpret the requirement for failure-to-
attain contingency measures to apply to Moderate PM2.5
nonattainment areas that cannot practicably attain the NAAQS by the
statutory attainment date. Rather, the EPA believes it is
appropriate for the state to identify and adopt attainment
contingency measures as part of the Serious area attainment plan
that it will develop once the EPA reclassifies the area. 81 FR
58067.
---------------------------------------------------------------------------

    The purpose of contingency measures is to continue progress in
reducing emissions during the period while a state is revising its SIP
to address a failure, such as a failure to meet a QM requirement or
failure to attain. The principal considerations for evaluating
contingency measures are:
     Contingency measures must be fully adopted rules or
control measures that are ready to be implemented quickly upon failure
to meet RFP or failure of the area to meet the NAAQS by its attainment
date.
     The SIP must contain trigger mechanisms for the
contingency measures, specify a schedule for implementation, and
indicate that the measures will be implemented without further action
by the state or by the EPA. In general, we expect all actions needed to
affect full implementation of the

measures to occur within 60 days after the EPA notifies the state of a
failure.
     The contingency measures shall consist of control measures
that are not otherwise included in the control strategy or that achieve
emissions reductions not otherwise relied upon in the control strategy
for the area.