Air Plan Approval; AK, Fairbanks North Star Borough; 2006 24-Hour PM2.5 Serious Area and 189(d) Plan

Federal RegisterJan 8, 2025

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R10-OAR-2024-0595; FRL-12391-02-R10]

Air Plan Approval; AK, Fairbanks North Star Borough; 2006 24-Hour PM

2.5

Serious Area and 189(d) Plan

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule.

SUMMARY:

The Environmental Protection Agency (EPA) is proposing to approve the state implementation plan (SIP) revisions submitted by the State of Alaska (Alaska or the State) on December 4, 2024, to address Clean Air Act requirements for the 2006 24-hour fine particulate matter (PM

2.5

) national ambient air quality standards in the Fairbanks North Star Borough Serious PM

2.5

nonattainment area. Alaska's submission includes SIP revisions to meet nonattainment planning requirements for emissions inventories, modeling and sulfur dioxide precursor demonstration for major stationary sources, control measures, attainment projections and progress to attainment and associated motor vehicle emissions budgets, and contingency measures. The EPA is also starting the adequacy process for the budgets.

DATES:

Comments.

Written comments must be received on or before February 7, 2025.

ADDRESSES:

Submit your comments, identified by Docket ID No. EPA-R10-OAR-2024-0595, at

https://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 the disclosure of which 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

https://www.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT:

Matthew Jentgen, EPA Region 10, 1200 Sixth Avenue, Suite 155, Seattle, WA 98101, (206) 553-0340,

jentgen.matthew@epa.gov.

SUPPLEMENTARY INFORMATION:

Throughout this document wherever “we,” “us,” or “our” is used, it is intended to refer to the EPA.

Table of Contents

I. Background

II. Review of the SIP Revisions to the Fairbanks Serious Plan and Fairbanks 189(d) Plan

A. Emissions Inventory

B. Pollutants Addressed

C. Control Strategy

D. Attainment Demonstration and Modeling

E. Reasonable Further Progress

F. Quantitative Milestones

G. Contingency Measures

H. Motor Vehicle Emission Budgets for Transportation Conformity

III. Summary of Proposed Action

A. Proposed Approval

B. Adequacy Process

IV. Interim Final Determination and Deferral of Sanctions

V. Incorporation by Reference

VI. Statutory and Executive Order Reviews

I. Background

In 2009, the EPA designated a portion of the Fairbanks North Star Borough as “nonattainment” for the 2006 24-hour PM

2.5

National Ambient Air Quality Standards (NAAQS), which is set at the level of 35 micrograms per cubic meter (μg/m

) (Fairbanks PM

2.5

Nonattainment Area) (74 FR 58688, November 13, 2009).

Effective July 2, 2014, the EPA classified the area as “Moderate” (79 FR 31566, June 2, 2014). Subsequently, Alaska submitted, and the EPA approved, a plan to meet the Moderate nonattainment area requirements (82 FR 42457, September 8, 2017) (Fairbanks Moderate Plan).

See

40 CFR 81.302.

On May 10, 2017, the EPA determined that the Fairbanks PM

2.5

Nonattainment Area failed to attain the 2006 24-hour PM

2.5

NAAQS in the area by the outermost statutory Moderate area attainment date of December 31, 2015 (82 FR 21711). The outermost attainment date is the latest date by which an area can attain the NAAQS per statute. As a result, the Fairbanks PM

2.5

Nonattainment Area was reclassified as a “Serious” nonattainment area by operation of law.

Upon reclassification as a Serious PM

2.5

nonattainment area, the State was required to submit a Serious area attainment plan satisfying the requirements of Clean Air Act (CAA or Act) sections 172, 189(b), and 189(c) and 40 CFR 51.1003(b). In accordance with CAA section 188(c)(2), the outermost attainment date for a Serious area is no later than the end of the tenth calendar year following designation (

i.e.,

December 31, 2019).

Alaska submitted a plan to address the Serious PM

2.5

nonattainment area requirements on December 13, 2019 (Fairbanks Serious Plan).

Along with the required planning elements, the Fairbanks Serious Plan included more stringent performance and operating requirements for residential and commercial heating devices, new regulations for wood sellers, and some requirements for stationary sources in the nonattainment area. The Fairbanks Serious Plan is comprised of revisions to Title 18, Chapter 50, of the Alaska Administrative Code (18 AAC 50) and the State Air Quality Control Plan, adopted and incorporated by reference into State law at 18 AAC 50.030(a).

On January 9, 2020, in accordance with CAA section 110(k)(1)(B), the EPA determined that the Fairbanks Serious Plan was administratively and technically complete (85 FR 7760, February 11, 2020).

We note that Alaska submitted a SIP revision on October 25, 2018, to address the preconstruction permitting new source review (NSR) requirements for the Fairbanks Serious nonattainment area, among other things. The EPA approved the submission as meeting the nonattainment NSR requirements for the Fairbanks Serious Plan on August 29, 2019 (84 FR 45419).

We note that 18 AAC 50.030(a) is not submitted, rather Alaska submits the adopted provisions separately for EPA approval.

Within the Fairbanks Serious Plan, the State sought an extension of the otherwise applicable attainment date through CAA section 188(e). On September 2, 2020, the EPA determined that the area failed to attain by the Serious area attainment date and denied the State's Serious area attainment date extension request (85 FR 54509). As a result, Alaska was required to submit a revised SIP submission to meet both the Serious area attainment plan requirements and the additional requirements set forth in CAA section 189(d) by December 31, 2020.

Alaska submitted the revised plan on December 15, 2020 (Fairbanks 189(d) Plan). The Fairbanks 189(d) Plan updated a number of chapters of the narrative portion of the State Air Quality Control Plan, adopted and incorporated by reference into State law at 18 AAC 50.030(a).

40 CFR 51.1003(c).

On September 24, 2021, the EPA approved the 2013 base year emissions inventory and the PM

2.5

precursor

demonstration elements of the Fairbanks Serious Plan as meeting the Serious area planning requirements (86 FR 52997). In the same action, the EPA approved other plan components as SIP strengthening, including: (1) the updated Fairbanks Emergency Episode Plan

that the State adopted on November 18, 2020, and submitted on December 15, 2020; and (2) the regulatory control measures included in the SIP submissions on October 25, 2018, and November 28, 2018 (in addition to the December 13, 2019, submission).

The EPA did not determine as part of the September 24, 2021, approval whether these SIP strengthening components met specific nonattainment plan requirements, including control strategy requirements in CAA section 189 and 40 CFR 51.1010 or the contingency measure requirements in CAA section 172(c)(9) and 40 CFR 51.1014.

State Air Quality Control Plan, Vol. II, section III.D.7.12 (

i.e.,

Alaska's planning chapter related to air quality forecasting and curtailment levels).

For a description of the specific control measures addressed across the State's SIP submissions, see 86 FR 52997, September 24, 2021.

Finally, on December 5, 2023, the EPA acted on the remaining elements required for a Serious nonattainment area that failed to attain by the Serious area attainment date. Table 1 of this preamble provides a summary of the December 5, 2023, final rule approving in part and disapproving in part the Fairbanks Serious Plan and Fairbanks 189(d) Plan.

88 FR 84626, December 5, 2023.

Table 1—Summary of the EPA's December 5, 2023, Final Rule

Description of CAA planning requirement

Approval

Disapproval

Base year emissions inventory for Serious areas subject to CAA section 189(b) * (CAA section 172(c)(3);

40 CFR 51.1008(b)(1))

Approval of the 2013 base year emissions inventory

Base year emissions inventory for areas subject to CAA section 189(d) (CAA section 172(c)(3); 40 CFR 51.1008(c)(1))

Approval of the 2019 base year emissions inventory

Attainment projected emissions inventory (CAA section 172(c)(1);

40 CFR 51.1008(c)(2))

Disapproval.

Serious area nonattainment plan control strategy that ensures that best available control measures (BACM), including best available control technologies (BACT), for the control of direct PM

2.5

and PM

2.5

precursors are implemented in the nonattainment area (CAA section 189(b)(1)(B);

40 CFR 51.1010(a))

Partial approval of the control strategy as meeting BACM and BACT requirements under CAA section 189(b)(1)(B)

and 40 CFR 51.1010(a) for the solid fuel home heating device source category and residential and commercial fuel oil combustion source category;

Partial approval of the control strategy approved as meeting BACM and BACT requirements under CAA section 189(b)(1)(B)

and 40 CFR 51.1010(a) for the charbroiler, used oil burner, and mobile source categories (except for rejection of vehicle anti-idling requirements);

Approval of specific regulations under 18 AAC 50.075 through 077 (except the requirements for dry wood sellers under 18 AAC 50.076(k)), and Fairbanks Emergency Episode Plan (except the contingency measure portion);

Disapproval of the control strategy BACM and BACT requirements (CAA section 189(b)(1)(B)

and 40 CFR 51.1010(a)) for the following emissions source categories: (1) Requirements for wood sellers; (2) Coal-fired heating devices; (3) Coffee roasters; (4) Weatherization and energy efficiency measures; (5) Mobile source category (disapproving for lack of vehicle anti-idling requirements);

Disapproval of the control strategy BACM and BACT requirements (CAA section 189(b)(1)(B)

and 40 CFR 51.1010(a)) for PM

2.5

and sulfur dioxide (SO

) for the Doyon-Fort Wainwright Central Heating and Power Plant, University of Alaska Fairbanks Campus Power Plant, Zehnder Power Plant, and North Pole Power Plant.

Partial approval as meeting applicable control strategy BACM and BACT requirements (CAA section 189(b)(1)(B) and 40 CFR 51.1010(a)) for ammonia (NH

) for the Chena Power Plant, Doyon-Fort Wainwright Central Heating and Power Plant, University of Alaska Fairbanks Campus Power Plant, Zehnder Power Plant, and North Pole Power Plant;

Partial approval of Alaska's PM

2.5

and NH

BACT determinations for the Doyon-Fort Wainwright Central Heating and Power Plant; PM

2.5

and NH

BACT determination for the University of Alaska Fairbanks Campus Power Plant, except for the three small diesel fired engines (EUs 23, 26, and 27); PM

2.5

and NH

BACT determinations for the Zehnder Power Plant; PM

2.5

and NH

BACT determinations for the North Pole Power Plant

Additional measures (beyond those already adopted in previous nonattainment plan SIP submissions for the area as RACM/RACT, BACM/BACT, and Most Stringent Measures (MSM)

(if applicable)) that provide for attainment of the NAAQS as expeditiously as practicable and, from the date of such submission until attainment, demonstrate that the plan will at a minimum achieve an annual five percent reduction in emissions of direct PM

2.5

or any PM

2.5

plan precursor. (CAA section 189(d);

40 CFR 51.1010(c))

Disapproval.

Attainment demonstration and modeling (CAA sections 188(c)(2) and 189(b)(1)(A);

40 CFR 51.1003(c) and 51.1011)

Disapproval.

Reasonable further progress (RFP) provisions (CAA section 172(c)(2);

40 CFR 51.1012)

Disapproval.

Quantitative milestones (CAA section 189(c);

40 CFR 51.1013)

Disapproval.

Motor vehicle emission budgets (CAA section 176, 40 CFR 51.1003(d) and 93.118)

Disapproval.

An adequate evaluation by the state of sources of all four PM

2.5

precursors for regulation, and implementation of controls on all such precursors, unless the state 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 PM

2.5

levels that exceed the standard.* (CAA section 189(e);

40 CFR 51.1006)

Approval of the State's comprehensive PM

2.5

precursor demonstrations for NO

and VOC emissions

Contingency measures applicable to Serious areas subject to CAA section 189(b) (CAA section 172(c)(9);

40 CFR 51.1014)

Disapproval of the contingency measures requirements of CAA section 172(c)(9)

and 40 CFR 51.1014 applicable to Serious areas subject to CAA sections 189(b) and 189(d).

Contingency measures applicable to Serious areas subject to CAA section 189(d) (CAA section 172(c)(9); 40 CFR 51.1014)

The EPA finalized a limited disapproval of the Fairbanks 189(d) Plan contingency measure because the contingency measure did not fully meet the contingency measure requirements of CAA section 172(c)(9) and 40 CFR 51.1014 but otherwise strengthened the SIP.

Nonattainment new source review provisions (CAA sections 172(c)(5), 189(b)(3), 189(d), and 189(e), and 40 CFR 51.165, 40 CFR 51.1003(b)(1)(viii), and 40 CFR 51.1003(c)(1)(viii)

Approval

The EPA finalized approval of this requirement on September 24, 2021 (86 FR 52997).

On December 4, 2024, Alaska made a SIP submission (Fairbanks Revised 189(d) Plan) intended to address the nonattainment requirements that were disapproved as part of the EPA's December 5, 2023, final rule. CAA sections 110(a)(1) and (2) and 110(l) require each state to provide reasonable public notice and opportunity for public hearing prior to the adoption and submission of a SIP or SIP revision to the EPA. To meet this requirement, every SIP submission must include evidence that the state provided adequate public notice and an opportunity for a public hearing consistent with the EPA's implementing regulations in 40 CFR 51.102.

42 U.S.C. 7502(c)(3).

42 U.S.C. 7502(c)(1).

42 U.S.C. 7513a(b)(1)(B).

Id.

42 U.S.C. 7513a(b)(1)(B).

MSM is applicable if the EPA has previously granted an extension of the attainment date under CAA section 188(e) for the nonattainment area and NAAQS at issue. The EPA denied Alaska's request to extend the Serious area attainment date for the Fairbanks PM

2.5

Nonattainment Area.

42 U.S.C. 7513a(d).

42 U.S.C. 7513(c)(2) and 7513a(b)(1)(A).

42 U.S.C. 7502(c)(2).

42 U.S.C. 7513a(c).

42 U.S.C. 7513a(e).

42 U.S.C. 7502(c)(9).

The EPA finalized a limited approval of the Fairbanks Emergency Episode Plan, State Air Quality Control Plan, Vol. II, section III.D.7.12, as SIP-strengthening on September 24, 2021. 86 FR 52997, September 24, 2021, at pp. 52997, 53004.

42 U.S.C. 7502(c)(5), 7513a(b)(3), 7513a(d), and 7513a(e).

On March 11, 2024, Alaska notified the public of the opportunity to review and comment on proposed regulatory changes related to the Fairbanks nonattainment area and announced two formal public hearings on April 10, 2024. The public comment period closed on May 10, 2024. Later, on August 26, 2024, Alaska opened a public comment period to solicit public review of amendments to numerous SIP sections and appendices and to notify the public of two hearings scheduled on September 26, 2024. On September 20 and 23, 2024, Alaska opened comment periods for the public to review each proposed permit revision to implement the State's proposed regulatory changes. The comment periods closed on October 22 and 25, 2024, respectively. The SIP submission includes evidence of the public notices and copies of written and oral comments received, with the State's associated responses. Therefore, we find that the submission meets the procedural requirements for public notice and hearing in CAA sections 110(a) and 110(l) and 40 CFR 51.102.

CAA section 110(k)(1)(B) requires the EPA to determine whether a SIP submission is complete within 60 days of receipt. This section also provides that any plan that the EPA has not affirmatively determined to be complete or incomplete will become complete by operation of law six months after the date of submission. The EPA reviewed the submission and finds it complete based on the EPA's SIP completeness criteria in 40 CFR part 51, appendix V.

See

“SIP Submittal Checklist for the Fairbanks North Star Borough PM

2.5

Nonattainment Area—2024 SIP revision,” EPA Region 10, Air and Radiation Division, included in the docket for this action.

Section II of this document summarizes the EPA's review of Alaska's SIP submission against the relevant CAA requirements. The EPA's technical analysis is detailed in technical support documents in the docket for this action.

II. Review of the SIP Revisions to the Fairbanks Serious Plan and Fairbanks 189(d) Plan

A. Emissions Inventory

1. Statutory and Regulatory Requirements

CAA section 172(c)(3) requires that states submit a comprehensive, accurate, and current inventory of actual emissions from all sources of the relevant pollutant or pollutants in the nonattainment area as part of a nonattainment plan for such area. On August 24, 2016, the EPA finalized regulations implementing SIP requirements for states with areas designated as nonattainment for the PM

2.5

NAAQS.

This rule is codified at 40 CFR part 51, subpart Z and is referred to herein as the PM

2.5

SIP Requirements Rule. The PM

2.5

SIP Requirements Rule at 40 CFR 51.1008 contains the requirements for emissions

inventories.

The EPA has also issued additional guidance concerning emissions inventories for PM

2.5

nonattainment areas.

In accordance with 40 CFR 51.1008, the attainment plan must include a base year emissions inventory and attainment projected emissions inventory.

Fine Particulate Matter National Ambient Air Quality Standards: State Implementation Plan Requirements, 81 FR 58010, August 24, 2016, at p. 58149.

81 FR 58010, August 24, 2016, at pp. 58078-58079.

“Emissions Inventory Guidance for Implementation of Ozone and Particulate Matter National Ambient Air Quality Standards (NAAQS) and Regional Haze Regulations,” EPA, May 2017 (“Emissions Inventory Guidance”), available at:

https://www.epa.gov/air-emissions-inventories/air-emissions-inventory-guidance-implementation-ozone-and-particulate.

The base year emissions inventory for a Serious PM

2.5

nonattainment area must be one of the three years for which the EPA used monitored data to reclassify the area to Serious, or another technically appropriate year justified by the state in its Serious area nonattainment plan SIP submission.

Similarly, the base year emissions inventory for a nonattainment area subject to CAA section 189(d) must be one of the three years for which monitored data were used by the EPA to determine the area failed to attain the PM

2.5

NAAQS by the applicable Serious area attainment date, or another technically appropriate year justified by the state in its Serious area nonattainment plan SIP submission.

The base year emissions inventory should provide a state's best estimate of actual emissions from all sources,

i.e.,

all emissions that contribute to the formation of PM

2.5

. The emissions must be either annual total emissions, average-season day emissions, or both, as appropriate for the relevant annual versus 24-hour PM

2.5

NAAQS. The state must include a rationale for providing annual or seasonal emissions inventories, and justification for the period used for any seasonal emissions calculations.

40 CFR 51.1008(b)(1).

40 CFR 51.1008(c)(1).

40 CFR 51.1008.

According to 40 CFR 51.1008, the Fairbanks Revised 189(d) Plan must include an attainment projected inventory for the nonattainment area. The year of the projected inventory shall be the most expeditious year for which projected emissions show modeled PM

2.5

concentrations below the level of the NAAQS. The emissions values shall be projected emissions of the same sources included in the base year inventory for the nonattainment area (

i.e.,

those only within the nonattainment area) and any new sources. The state shall include in this inventory projected emissions growth and contraction from both controls and other causes during the relevant period. The temporal period of emissions shall be the same temporal period (annual, average-season-day, or both) as the base year inventory for the nonattainment area. The same sources reported as point sources in the base year inventory for the nonattainment area shall be included as point sources in the attainment projected inventory for the nonattainment area. Stationary nonpoint and mobile source projected emissions shall be provided using the same detail (

e.g.,

state, county, and process codes) as the base year inventory for the nonattainment area. The same detail of the emissions included shall be consistent with the level of detail and data elements as in the base year inventory for the nonattainment area (

i.e.,

as required by 40 CFR part 51, subpart A). Consistent with the base year inventory for the nonattainment area, the inventory shall include direct PM

2.5

emissions, separately reported PM

2.5

filterable and condensable emissions, and emissions of the scientific PM

2.5

precursors, including precursors that are not significant PM

2.5

plan precursors pursuant to a precursor demonstration under 40 CFR 51.1006.

A state's SIP submission must include documentation explaining how it calculated emissions data for the inventory and be consistent with the data elements required by 40 CFR part 51, subpart A.

In estimating mobile source emissions, a state must use the latest emissions models and planning assumptions available at the time the SIP is developed.

States are also required to use the EPA's “Compilation of Air Pollutant Emission Factors” (“AP-42”) road dust method for calculating re-entrained road dust emissions from paved roads.

34 35

40 CFR 51.1008(c); (a)(1)(v); 81 FR 58010, August 24, 2016, at pp. 58027-29.

See

CAA section 172(c)(3).

The EPA released an update to AP-42 in January 2011 that revised the equation for estimating paved road dust emissions based on an updated data regression that included new emissions tests results. 76 FR 6328 (February 4, 2011).

AP-42 has been published since 1972 as the primary source of the EPA's emission factor information.

https://www.epa.gov/air-emissionsfactors-and-quantification/ap-42-compilation-airemissions-factors.

It contains emission factors and process information for more than 200 air pollution source categories. A source category is a specific industry sector or group of similar emitting sources. The emission factors have been developed and compiled from source test data, material balance studies, and engineering estimates.

2. Summary of the EPA's Prior Rulemaking Regarding the Emissions Inventory

On December 5, 2023, the EPA finalized approval of the base year emissions inventory, but the EPA finalized disapproval of the projected attainment year emissions inventory. The EPA stated that, due to the insufficient control strategy, the attainment projected emissions inventory did not necessarily take into consideration all required emissions reductions.

3. Summary of the State's Submission Regarding the Emissions Inventory

Based on the EPA's approval of the initial Fairbanks 189(d) Plan's base year emissions inventory, Alaska retained State Air Quality Control Plan, Vol. II, section III.D.7.6.2. However, Alaska has since updated the modeling platform and included a 2020 base year emissions inventory in the Fairbanks Revised 189(d) Plan. The modeling platform includes key elements such as the meteorological modeling, air quality modeling, and model emissions inventories. The base year planning emissions inventory for direct PM

2.5

and PM

2.5

precursors (nitrogen oxides (NO

), SO

, volatile organic compounds (VOC), and ammonia (NH

)) and the documentation for the inventory for the Fairbanks PM

2.5

Nonattainment Area are located in the updated Fairbanks Emissions Inventory section.

State Air Quality Control Plan, Vol. II, section III.D.7.6.9.

For projecting attainment, the 2020 base year emissions inventory incorporates the ambient monitoring data used to establish the baseline design value. Alaska stated that the 2020 base year emissions inventory accounts for emissions reductions from control measures adopted and implemented through December 31, 2019. Projected control measure-driven emissions reductions are then applied to evaluate the appropriate attainment date. Alaska also noted that, for planning purposes, the base year emissions inventory represents a baseline of nonattainment area emissions to demonstrate five percent per year emissions reductions.

Alaska stated that the Fairbanks Revised 189(d) Plan includes an entirely new photochemical modeling platform and, for the emissions inventory, features a new, more current winter 2019-2020 modeling episode. Episodic emissions for the 2020 base year inventory were based on activity collected to represent this 74-day 2019-2020 period.

For point sources, day- and hour-specific fuel use for the new 2019-2020 modeling episode were obtained by Alaska from each of the point source facilities within the nonattainment area. Alaska noted that unlike the base year emissions inventories from earlier versions of the nonattainment plan, which projected episodic emissions from 2008 to 2013 and 2019, respectively, Alaska stated that the 2020 base year point source emissions inventory was based on the actual data during the modeling episodes.

Alaska stated that, for space heating area sources, space heating energy usage estimates for the 2020 base year emissions inventory were based on a comprehensive new Fairbanks Home Heating survey, conducted in the spring of 2023. Respondents were asked to provide information on fuel usage by device in their household for the most recent two calendar years (2021 and 2022) as well as the six-month winter period between October 2022 and March 2023. Data from this 2023 survey were used to replace projected space heating emissions developed under previous SIP revisions using earlier 2011-2015 surveys. Alaska noted that decreases in the fraction of wood devices used in the nonattainment area and the amount of wood use per device from the survey respondents tracked well with downward trajectories of wood use expected from existing and on-going control programs such as the Fairbanks North Star Borough's (FNSB) Wood Stove Change Out Program and the Alaska DEC's Solid Fuel-Burning Appliance Curtailment Program. Alaska stated that survey results were then back-casted to calendar year 2020 to provide a more realistic estimate of wood-fired heating use for the 2020 base year emissions inventory.

For a description of the “back-cast” method, see Kotchenruther, Robert. (November 21, 2024).

Technical support document for Alaska Department of Environmental Conservation's amendments to: State Air Quality Control Plan, Emission Inventory Data (version August 19, 2024).

U.S. Environmental Protection Agency, Region 10, Laboratory Services and Applied Science Division, EPA-R10-OAR-2024-0595, section 1.5.

For on-road and non-road mobile sources, Alaska noted that the previous base year emissions inventories included on-road vehicle populations and age distributions based on 2014 and 2018 department of motor vehicle (DMV) registration data, respectively. For the Fairbanks Revised 189(d) Plan, 2020 DMV registration data were used to align with the 2020 base year emissions inventory year. For on-road mobile sources, these 2020 DMV data were used to develop vehicle population, age distribution, and fuel type/technology inputs to the MOVES3 vehicle emissions model. For aircraft activity specifically, a recent adjustment to aircraft activity in the initial Fairbanks 189(d) Plan was made to reflect lower aircraft activity during the winter months. Otherwise, the estimates of aircraft activity in the Fairbanks Revised 189(d) Plan were unchanged. Table 2 of this preamble includes a summary of the base year emissions inventory.

Table 2—2020 Base Year Episode Average Daily Emissions by Source Sector

Source sector

2020 base year emissions inventory

(tons/day)

2.5

VOC

Point Sources

0.58

13.54

6.63

0.04

0.888

Area, Space Heating

1.97

2.17

3.61

6.66

0.109

Area, Space Heat, Wood

1.89

0.23

0.04

6.55

0.067

Area, Space Heat, Oil

0.06

1.72

3.54

0.10

0.003

Area, Space Heat, Coal

0.00

Area, Space Heat, Other

0.02

0.22

0.02

0.01

0.039

Area, Other

0.11

0.36

0.03

2.21

0.047

Mobile, On-Road

0.07

1.18

0.000

1.42

0.040

Mobile, Aircraft

0.12

0.43

5.44

0.15

0.000

Mobile, Non-Road excluding aircraft

0.09

0.29

0.00

2.64

0.0001

Totals

2.95

17.96

15.71

13.04

0.285

Source: State Air Quality Control Plan, Vol. II, section III.D.7.6, Table 7.6-9.

Alaska noted for PM

2.5

overall, the 2020 base year emissions in the Fairbanks Revised 189(d) Plan are nine percent lower than the 2019 base year emissions inventory in the initial Fairbanks 189(d) Plan, with differences coming from space heating and mobile sources that are likely the result of on-going emissions controls.

For more details of the 2019 base year emissions inventory,

see

88 FR 1454, January 10, 2023, at p. 1460.

Alaska stated that NO

and SO

emissions in the Fairbanks Revised 189(d) Plan are 17 and nine percent higher respectively than in the initial Fairbanks 189(d) Plan. Alaska asserted that these emissions increases are largely driven by changes in the Point (and Other Area) source emissions, since the new 74-day 2019-2020 modeling episode was based on actual emissions. In addition, the increases in NO

and SO

emissions for the Other Area source sector under the Fairbanks Revised 189(d) Plan are due to moving stationary source emissions from Eielson AFB to this sector. Under the previous base year emissions inventories, stationary source emissions from Eielson were contained in the Point source portion of the inventory.

The reductions in VOC emissions in the Fairbanks Revised 189(d) Plan are due to mobile source sector reductions in the MOVES3 model. The initial Fairbanks 189(d) Plan inventory was based on an earlier version of MOVES that reflected higher VOC emission factors. In addition, Alaska stated that VOC reductions in the Space Heating sector are likely the result of differences in the mix of wood use by device between the two inventories. The Fairbanks Revised 189(d) Plan inventory reflects higher usage fractions of certified and pellet-based wood burning devices based on data from new 2023 Home Heating survey, and these devices have lower VOC emission factors.

Finally, Alaska noted that the difference in overall NH

emissions between the two base year inventories is very modest (one percent lower under

the Fairbanks Revised 189(d) base year emissions inventory). These source sector-specific variations mirror the adjustments made to PM

2.5

, SO

, NO

, and VOC emissions discussed earlier in this section II.A of this preamble.

Building from Alaska's new 2020 base year emissions inventory, Alaska developed its attainment projections. As a first step, Alaska constructed a 2027 baseline emissions inventory that reflected projected activity growth factors, previously implemented control measures, and other adjustments to point sources and wood usage.

State Air Quality Control Plan, Vol. II, section III.D.7.6, Table 7.6-11.

As a second step, Alaska developed the 2027 projected attainment emissions inventory by adjusting the 2027 baseline inventory to account for projected emissions reductions from the control strategy included in the Fairbanks Revised 189(d) Plan. For a complete list of measures included in Alaska's control strategy, see Table 4 in section II.D of this preamble below. Notably, as part of the control strategy, the Wood Stove Change Out Program and the Oil-To-Gas Conversion Program are managed by the local Fairbanks North Star Borough. Direct PM

2.5

reductions from these programs in 2020 through 2026 totaled over 1.3 tons per episode day. The State of Alaska manages the Solid Fuel-Burning Appliance Curtailment Program as well as seven other control measures for which emissions benefits were quantified and incorporated into the 2027 attainment projected inventory. Notably, the State recently increased the stringency of the curtailment program by lowering the alert stages to 20 μg/m

and 30 μg/m

, respectively. Alaska also utilized funding from the 2019-2020 Targeted Airshed Grant (TAG) to purchase three dynamic message highway signs and an infrared camera and to expand staffing to increase compliance. For details of these projected emissions reductions, see the spreadsheet calculations in the State Air Quality Control Plan, Vol. III, Appendix III.D.7.6.

Alaska concluded that, after considering the emissions reductions from these control measures, the Fairbanks PM

2.5

Nonattainment Area could demonstrate attainment by 2027, based on the 2027 attainment year emissions inventory, as summarized in Table 3 of this preamble.

Table 3—2027 Projected Attainment Emissions Inventory, Average Daily Emissions by Source Sector

Source sector

2027 Projected attainment emissions inventory

(tons/day)

2.5

VOC

Point Sources

0.62

14.60

7.15

0.04

0.095

Area, Space Heating

0.74

2.34

1.98

8.01

0.124

Area, Space Heat, Wood

0.70

0.28

0.04

7.90

0.081

Area, Space Heat, Oil

0.02

1.83

1.91

0.10

0.004

Area, Space Heat, Coal

0.00

Area, Space Heat, Other

0.02

0.22

0.02

0.01

0.039

Area, Other

0.13

0.40

0.03

2.33

0.051

Mobile, On-Road

0.05

0.65

0.00

1.08

0.038

Mobile, Aircraft

0.12

0.45

5.70

0.17

0.000

Mobile, Nonroad excluding aircraft

0.08

0.32

0.00

2.22

0.002

Totals

1.74

18.75

14.86

13.85

0.310

Source: State Air Quality Control Plan, Vol. II, section III.D.7.6, Table 7.6-19.

Alaska observed that the 2027 projected attainment emissions inventory provides reductions in total PM

2.5

and SO

emissions within the nonattainment area of 41 percent and five percent respectively. Within the space heating sector, which has a proportionally higher impact on ambient PM

2.5

, Alaska noted that the 2027 projected attainment emissions inventory reductions were 63 percent and 45 percent for direct PM

2.5

and SO

, respectively.

4. EPA Evaluation and Proposed Action Regarding the Emissions Inventory

a. 2020 Base Year Emissions Inventory

The EPA proposes to approve the 2020 base year emissions inventory as meeting the requirements of CAA section 172(c)(3) and 40 CFR 51.1008. The EPA is proposing to determine that Alaska has justified that 2020 is a technically appropriate inventory year consistent with 40 CFR 51.1008(c)(1). The base year emissions inventory includes actual emissions of all sources within the nonattainment area. The EPA proposes to determine that a seasonal episode daily average inventory is appropriate for the Fairbanks PM

2.5

Nonattainment Area because the area experiences episodic elevated concentrations of PM

2.5

during wintertime cold weather events. The emissions inventory includes direct PM

2.5

emissions, separately reported as filterable and condensable emissions, as well as all scientific PM

2.5

precursors (SO

, NO

, VOC, and NH

). Alaska reported emissions for point sources according to the point source emissions thresholds of the Air Emissions Reporting Rule in 40 CFR part 51, subpart A. Finally, the emissions inventory is consistent with the detail and data elements required by 40 CFR part 51, subpart A. For the EPA's full evaluation, see the EPA's technical evaluation of Alaska's emissions inventory included in the docket for this action.

Kotchenruther, Robert. (November 21, 2024).

Technical support document for Alaska Department of Environmental Conservation's amendments to: State Air Quality Control Plan, Emission Inventory Data (version August 19, 2024).

U.S. Environmental Protection Agency, Region 10, Laboratory Services and Applied Science Division, EPA-R10-OAR-2024-0595.

b. 2027 Projected Attainment Emissions Inventory

The EPA proposes to approve the 2027 projected attainment emissions inventory as meeting the requirements of CAA section 172(c)(3) and 40 CFR 51.1008. The EPA is proposing to determine that 2027 is the most expeditious year for which projected emissions show modeled PM

2.5

concentrations below the level of the NAAQS. As discussed in section II.D of this preamble, Alaska included a model output for 2026 that resulted in emissions levels exceeding the 2006 24-

hour PM

2.5

NAAQS. The attainment projected inventory includes the sources in the base year emissions inventory and accounts for growth and contraction from both controls and other causes. Consistent with the base year emissions inventory, the attainment projected emissions inventory is based on episode average daily emissions. The attainment projected emissions inventory includes direct PM

2.5

emissions, separately reported as filterable and condensable emissions, as well as all scientific precursors. The attainment projected emissions inventory includes the same level of emissions detail for the same point sources and for mobile sources reported in the base year emissions inventory. For the EPA's full evaluation, see the EPA's technical evaluation of Alaska's emissions inventory, included in the docket for this action.

Kotchenruther, Robert. (November 21, 2024).

Technical support document for Alaska Department of Environmental Conservation's amendments to: State Air Quality Control Plan, Emission Inventory Data (version August 19, 2024).

U.S. Environmental Protection Agency, Region 10, Laboratory Services and Applied Science Division, EPA-R10-OAR-2024-0595.

B. Pollutants Addressed

1. Statutory and Regulatory Requirements Regarding the Pollutants Addressed

Under subpart 4 of part D, title I of the CAA and the PM

2.5

SIP Requirements Rule, each state containing a PM

2.5

nonattainment area must evaluate all PM

2.5

precursors for regulation unless, for any given PM

2.5

precursor, the state demonstrates to the Administrator's satisfaction that such precursor does not contribute significantly to PM

2.5

levels that exceed the NAAQS in the nonattainment area.

The provisions of subpart 4 do not define the term “precursor” for purposes of PM

2.5

, nor do they explicitly require the control of any specifically identified PM

2.5

precursor. The statutory definition of “air pollutant,” 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 SO

, NO

, VOCs, and NH

as precursors to the formation of PM

2.5

Accordingly, the attainment plan requirements of part D, title I of the CAA and the PM

2.5

SIP Requirements Rule apply to emissions of all four precursors and direct PM

2.5

from all types of stationary, area, and mobile sources, except as otherwise provided in CAA section 189(e).,

40 CFR 51.1006, 51.1010;

See

81 FR 58010, August 24, 2016, at pp. 58017-58020.

CAA section 302(g).

81 FR 58010, August 24, 2016, at p. 58015.

As noted in the EPA's Final Policy Assessment for the reconsideration of the PM

2.5

NAAQS, secondary particulate matter is formed in the atmosphere by photochemical oxidation reactions of both inorganic and organic gas-phase precursors. Precursor gases include SO

, NO

, NH

, and VOC gases of anthropogenic or natural origin. Anthropogenic SO

and NO

are the predominant precursor gases in the formation of secondary PM

2.5

sulfate and nitrate, and NH

is the gas-phase precursor for PM

2.5

ammonium. PM

2.5

ammonium formation is enhanced by particle acidity resulting from sulfuric acid and nitric acid condensation onto particles. Atmospheric oxidation of VOCs, both anthropogenic and biogenic, is an important source of organic aerosols, particularly in summer. The semi-volatile and nonvolatile products of VOC oxidation reactions can condense onto existing particles or can form new particles.

“Policy Assessment for the Reconsideration of the National Ambient Air Quality Standards for Particulate Matter” (EPA/452/R-22-004), EPA, May 2022), p. 2-10.

According to the State, total wintertime PM

2.5

concentrations in the Fairbanks PM

2.5

Nonattainment Area are a function of both primary PM

2.5

emissions and secondary PM

2.5

formed from precursors (see State Air Quality Control Plan, Vol. II, section III.D.7.8.1).

CAA section 189(e) requires that the control requirements for major stationary sources of direct PM

and PM

2.5

also apply to major stationary sources of PM

and PM

2.5

precursors, except where the Administrator determines that such sources do not contribute significantly to PM

or PM

2.5

levels that exceed the standard in the area. CAA section 189(e) contains the only express exception to the control requirements under subpart 4 (

e.g.,

requirements for reasonably available control measures (RACM) and reasonably available control technology (RACT), BACM and BACT, Most Stringent Measures (MSM), and New Source Review (NSR) for sources of direct PM

2.5

and PM

2.5

precursor emissions). Although CAA section 189(e) explicitly addresses only major stationary sources, the EPA interprets this provision as authorizing it also to determine, under appropriate circumstances, that regulation of specific PM

or PM

2.5

precursors from other source categories in a given nonattainment area is not necessary.

For example, under the EPA's longstanding interpretation of the control requirements that apply to stationary, area, and mobile sources of PM

precursors in the nonattainment area under CAA section 172(c)(1) and subpart 4,

a state may demonstrate in a SIP submission that control of a certain precursor pollutant is not necessary in light of its insignificant contribution to ambient PM

or PM

2.5

levels in the nonattainment area.

The requirements for attainment plans for the 2006 24-hour PM

2.5

NAAQS include the general nonattainment area planning requirements in CAA section 172 of title I, part D, subpart 1 and the additional planning requirements specific to particulate matter in CAA sections 188 and 189 of title I, part D, subpart 4. 81 FR 58010, August 24, 2016, at pp. 58012-58014.

The general attainment plan requirements of subpart 1, part D, of title I of the CAA in addition to the specific requirements in subpart 4, part D, of Title I of the CAA apply to both PM

and PM

2.5

See

81 FR 58010, August 24, 2016, at pp. 58013.

81 FR 58010, August 24, 2016, at pp. 58018-58019.

State Implementation Plan; General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990 (“General Preamble”), 57 FR 13498, April 16, 1992, at pp. 13539-42.

40 CFR 51.1006.

See also

81 FR 58010, 58033. Courts have upheld this approach to the requirements of subpart 4 for PM

10. See,

e.g.,

Assoc. of Irritated Residents

EPA,

et al., 423 F.3d 989 (9th Cir. 2005).

Under the PM

2.5

SIP Requirements Rule, a state may elect to submit to the EPA a “comprehensive precursor demonstration” for a specific nonattainment area to show that emissions of a particular precursor from all existing sources located in the nonattainment area do not contribute significantly to PM

2.5

levels that exceed the NAAQS at issue in the nonattainment area.

If the EPA determines that the contribution of the precursor to PM

2.5

levels in the area is not significant and approves the demonstration, then the state is not required to control emissions of the relevant precursor from existing sources in the attainment plan.

40 CFR 51.1006(a)(1).

Relatedly, under the PM

2.5

SIP Requirements Rule, a state may submit to the EPA a “major stationary source precursor demonstration” for a specific nonattainment area that shows that emissions of a particular precursor from all existing major stationary sources located in the nonattainment area do not contribute significantly to PM

2.5

levels that exceed the standard in the area.

If the EPA approves a major stationary source precursor demonstration, then the state is not required to control emissions of the relevant precursor from existing major stationary sources in the current attainment plan.

40 CFR 51.1006(a)(2).

40 CFR 51.1006(a)(2)(iii).

In addition, in May 2019, the EPA issued the “PM

2.5

Precursor Demonstration Guidance” (“PM

2.5

Precursor Guidance”), which provides recommendations to states for analyzing nonattainment area PM

2.5

emissions and developing such optional precursor demonstrations, consistent with the PM

2.5

SIP Requirements Rule.

“PM

2.5

Precursor Demonstration Guidance,” EPA-454/R-19-004, May 2019, including Memo dated May 30, 2019, from Scott Mathias, Acting Director, Air Quality Policy Division and Richard Wayland, Director, Air Quality Assessment Division, Office of Air Quality Planning and Standards (OAQPS), EPA to Regional Air Division Directors, Regions 1-10, EPA.

The EPA evaluated the Fairbanks Revised 189(d) Plan in accordance with the presumption embodied within subpart 4 that the State must address all PM

2.5

precursors in the evaluation and implementation of potential control measures, unless the State adequately demonstrates that emissions of a particular precursor or precursors do not contribute significantly to ambient PM

2.5

levels that exceed the PM

2.5

NAAQS in the nonattainment area. In reviewing any determination by the state to exclude a PM

2.5

precursor from the required evaluation of potential control measures, we consider both the magnitude of the precursor's contribution to ambient PM

2.5

concentrations in the nonattainment area and the sensitivity of ambient PM

2.5

concentrations in the area to reductions in emissions of that precursor.

40 CFR 51.1006(a)(1)(i) and (ii).

2. Summary of the EPA's Prior Rulemaking Regarding the Pollutants Addressed

On December 5, 2023, the EPA finalized approval of Alaska's precursor demonstration that NO

and VOCs are not significant precursors to PM

2.5

formation in the Fairbanks PM

2.5

Nonattainment Area.

88 FR 84626, December 5, 2023, at p. 84675.

3. Summary of the State's Submission Regarding the Pollutants Addressed

In the Fairbanks Revised 189(d) Plan, in accordance with 40 CFR 51.1006(a)(2), Alaska included a demonstration that SO

emissions from major stationary sources do not significantly contribute to PM

2.5

formation in the Fairbanks PM

2.5

Nonattainment Area. As discussed in the State Air Quality Control Plan, Vol. II, section III.D.7.8.15, Alaska stated that it utilized a new model platform that accurately simulated the formation of precursors into PM

2.5

in the Fairbanks environment. The new model platform also demonstrated marked improvement in the simulation of sulfate formation from SO

emissions as compared to prior platforms used by Alaska. Using the new model platform, Alaska performed a concentration-based contribution analysis using air quality modeling with “zero-out” model runs. Alaska's analysis showed that major stationary sources contributed 0.21 μg/m

2.5

at regulatory monitoring sites in Fairbanks including the North Pole monitor (Hurst Road), which is below the 1.5 μg/m

2.5

threshold included in the EPA's guidance.

See

State Air Quality Control Plan, Vol. II., section III.D.7.8.15, Table 7.8.18-1.

According to Alaska, the updated analysis of precursor impacts on PM

2.5

utilized a photochemical grid model (PGM) that accounted for the non-linear secondary effects of precursor gases. PGMs account for the atmospheric chemistry, transport, and deposition of pollutants using local emissions and meteorological data. The zero-out approach compared a baseline model run with a model run where a precursor's emissions are set to zero to determine the influence of that precursor on PM

2.5

formation.

Alaska noted that a concentration-based analysis was completed that excluded all sources of SO

. The monitored filter sulfate and the concentrations from the 5-year design value showed total sulfate from all sectors was 5.9 μg/m

or 21 percent of the PM

2.5

at an air quality monitor located in the City of Fairbanks (NCore) and 5.9 μg/m

or nine percent of the PM

2.5

at the North Pole air quality monitor (Hurst Road). When accounting for all emissions sources, SO

remained a significant precursor to PM

2.5

formation in the Fairbanks PM

2.5

Nonattainment Area.

After completing the first step, the major stationary source sector SO

precursor model runs were then performed based on the emissions for the 2020 base year and a model run that excluded SO

emissions. The difference in sulfate for a model simulation using base year emissions and a second model simulation with major stationary-source SO

emissions set to zero was compared with the 1.5 ug/m

threshold. Alaska stated that this concentration-based modeling demonstrated the insignificance of SO

from major stationary sources when compared with the 1.5 μg/m

threshold in the EPA's guidance, and therefore, a sensitivity-based contribution analysis was not needed, in accordance with 40 CFR 51.1006(a)(2)(ii).

4. The EPA's Evaluation and Proposed Action Regarding the Pollutants Addressed

The EPA evaluated the State's precursor demonstration included in the Fairbanks Revised 189(d) Plan. The EPA proposes to determine that Alaska's submission meets the requirements of 40 CFR 51.1006(a)(2) and is consistent with the EPA guidance.

Regarding the State's analytical approach, the EPA proposes to find that the State used appropriate methods and data to evaluate PM

2.5

formation in the Fairbanks PM

2.5

Nonattainment Area from precursor emissions. Consistent with 40 CFR 51.1006(a)(2), Alaska's submission includes a concentration-based contribution analysis. The concentration-based analysis shows that the SO

emissions from major stationary sources do not significantly contribute to PM

2.5

formation in the Fairbanks PM

2.5

Nonattainment Area. Specifically, Alaska's analysis shows that SO

emissions from major stationary sources contribute 0.21 μg/m

of PM

2.5

at the North Pole Hurst Road air quality monitor—far below the 1.5 μg/m

threshold included in the EPA guidance. For the EPA's full evaluation, see EPA's Technical Support Document.

Therefore, the EPA proposes to approve Alaska's precursor demonstration submitted as part of the Fairbanks Revised 189(d) Plan as demonstrating that the contribution of SO

from existing major stationary sources to PM

2.5

levels in the Fairbanks PM

2.5

Nonattainment Area is not significant in accordance with 40 CFR 51.1006(a)(2)(i). If the EPA finalizes approval as proposed, Alaska will not be required to control SO

emissions from existing major stationary sources in the Fairbanks PM

2.5

Nonattainment Area, pursuant to CAA section 189 and 40 CFR 51.1010. For purposes of the Fairbanks Revised 189(d) Plan, the PM

2.5

plan precursors are: NH

and SO

for all sources except for major stationary sources.

“PM

2.5

Briggs, Nicole. (December 2, 2024).

Review of Attainment Demonstration Modeling and SO

Precursor Demonstration in the 2024 State Implementation Plan Submission for the Fairbanks 24-hour PM

2.5

Nonattainment Area.

U.S. Environmental Protection Agency, Region 10, Laboratory Services and Applied Science Division, EPA-R10-OAR-2024-0595.

Consistent with its past actions, if finalized, the EPA's approval of Alaska's

precursor demonstration would not extend to nonattainment NSR requirements for the area. Alaska previously determined that it was appropriate to regulate NO

, SO

, VOCs, and NH

as precursors to PM

2.5

with respect to nonattainment NSR and submitted rule changes to that effect on October 25, 2018. The EPA approved the submitted revised program as meeting nonattainment NSR requirements triggered upon reclassification of the Fairbanks PM

2.5

Nonattainment Area to Serious (84 FR 45419, August 29, 2019).

C. Control Strategy

1. Statutory and Regulatory Requirements Regarding the Control Strategy

CAA section 189(b) and 40 CFR 51.1010(a) contain the control measure requirements for Serious areas. CAA section 189(d) and 40 CFR 51.1010(c) contain the control measure requirements for Serious areas that fail to attain.

Pursuant to CAA section 189(b) and 40 CFR 51.1010(a), the state must identify, adopt, and implement best available control measures, including best available control technologies, on sources of direct PM

2.5

emissions and sources of emissions of PM

2.5

plan precursors located in any Serious PM

2.5

nonattainment area or portion thereof located within the state. This level of control stringency is commonly called “BACM” and “BACT.” The regulation at 40 CFR 51.1010(a) specifies the requirements states must meet to identify potential control measures and in determining the measures states must include in the control strategy as BACM or BACT for the nonattainment area:

The state must identify all sources of direct PM

2.5

emissions and sources of emissions of PM

2.5

precursors in the nonattainment area, in accordance with the emissions inventory requirements in 40 CFR 51.1008(b).

The state must identify all potential control measures to reduce emissions from all sources of direct PM

2.5

emissions and sources of emissions of PM

2.5

plan precursors in the nonattainment area. The state must survey other NAAQS nonattainment areas in the U.S. and identify any measures for direct PM

2.5

and PM

2.5

plan precursors not previously identified by the state during the development of the Moderate area or Serious area attainment plan for the area.

The state must identify, adopt, and implement the best available control measures for each emission source. However, the state may demonstrate that any measure identified under 40 CFR 51.1010(a)(2) is not technologically or economically feasible to implement in whole or in part by the end of the tenth calendar year following the effective date of designation of the area and may eliminate such whole or partial measure from further consideration. Overall, economic feasibility is a less significant factor in the BACM and BACT determination process.

There are considerations for technological feasibility of a potential control measure, where a state may consider factors including but not limited to a source's processes and operating procedures, raw materials, physical plant layout, and potential environmental impacts such as increased water pollution, waste disposal, and energy requirements.

There are also considerations for economic feasibility of a potential control measure where a state may consider capital costs, operating and maintenance costs, and cost effectiveness of the measure.

In assessing whether a control measure or technology is BACM or BACT, the state must consider emissions reduction measures with higher costs per ton compared to the economic feasibility criteria applied in their RACM or RACT analysis.

With respect to determining BACT pursuant to CAA section 189(b), the EPA expects that states use the top-down BACT analysis process used in the Prevention of Significant Deterioration (PSD) Program.

Id.

40 CFR 51.1010(a)(3)(i); 81 FR 58010, August 24, 2016, at p. 58084.

40 CFR 51.1010(a)(3)(ii); 81 FR 58010, August 24, 2016, at p. 58085.

81 FR 58010, August 24, 2016, at p. 58085.

Id.

at p. 58080 (“Consistent with past policy, BACT determinations for PM

2.5

NAAQS implementation are to follow the same process and criteria that are applied to the BACT determination process for the PSD program.”).

Pursuant to CAA section 189(b), a state with a Serious nonattainment area must include provisions to assure the implementation of BACM and BACT-level controls on sources of direct PM

2.5

and PM

2.5

plan precursors no later than 4 years after the date the area is classified (or reclassified) as a Serious area.

In the preamble to the final PM

2.5

SIP Requirements Rule, the EPA recommended the following the 5-Step BACM/BACT selection process that states should follow to satisfy the analytical and substantive requirements of 40 CFR 51.1010(a) and CAA section 189(b):

Id.

at pp. 58084-85.

Step 1:

Develop a comprehensive inventory of sources and source categories of directly emitted PM

2.5

and PM

2.5

precursors.

Step 2:

Identify potential control measures for all such sources.

Step 3:

Determine whether an available control measure or technology is technologically feasible.

Step 4:

Determine whether an available control measure or technology is economically feasible.

Step 5:

Determine the earliest date by which a control measure or technology can be implemented in whole or in part in the area.

The EPA interprets CAA section 189(b) to require the state to determine what is BACM or BACT for a particular source or source category.

The EPA's longstanding interpretation of the CAA is that BACM and BACT determinations are to be generally independent of attainment for purposes of implementing the PM

2.5

NAAQS.

The EPA interprets the CAA requirement to impose BACM/BACT level control as requiring more emphasis on what controls are the best for the relevant source and whether those controls are feasible rather than on the attainment needs of the area.

States also may not decline to evaluate, or to control as necessary, sources or source categories on the basis that they are de minimis.

Id.

at p. 58081.

State Implementation Plans for Serious PM-10 Nonattainment Areas, and Attainment Date Waivers for PM-10 Nonattainment Areas Generally; Addendum to the General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990 (“Addendum to the General Preamble”), 59 FR 41998, at p. 42011 (August 16, 1994); 81 FR 58010, August 24, 2016, at p. 58081.

Id.

at p. 58082.

Subsequently, for a state with a Serious PM

2.5

nonattainment area that has failed to attain by the applicable attainment date, the state must submit a revised attainment plan with a control strategy that demonstrates that each year the area will achieve at least a five percent reduction in emissions of direct PM

2.5

or a five percent reduction in emissions of a PM

2.5

plan precursor based on the most recent emissions inventory for the area; and that the area will attain the standard as expeditiously as practicable consistent with the attainment date requirements under 40 CFR 51.1004(a)(3).

The regulation at 40 CFR 51.1010(c) specifies the following process the state must follow in determining which measures must be included in the control strategy:

CAA section 189(d), 42 U.S.C. 7513a(d), and 40 CFR 51.1010(c).

The state shall identify all sources of direct PM

2.5

emissions and sources of

emissions of PM

2.5

precursors in the nonattainment area in accordance with the emissions inventory requirements in 40 CFR 51.1008(b).

The state shall identify all potential control measures to reduce emissions from all sources of direct PM

2.5

emissions and sources of emissions of PM

2.5

plan precursors in the nonattainment area. For the sources and source categories represented in the emissions inventory for the nonattainment area, the state shall identify the most stringent measures (MSM) for reducing direct PM

2.5

and PM

2.5

plan precursors adopted into any SIP or used in practice to control emissions in any state, as applicable.

The state shall also reconsider and reassess any measures previously rejected by the state during the development of any Moderate area or Serious area attainment plan control strategy for the area. Similar to the requirements for Serious area plans, the state may make a demonstration for a 189(d) plan that a measure is not technologically or economically feasible to implement in whole or in part within 5 years or such longer period as the EPA may determine is appropriate after the EPA's determination that the area failed to attain by the Serious area attainment date and may eliminate such whole or partial measure from further consideration. There are considerations for technological feasibility of a potential control measure, as described under 40 CFR 51.1010(c)(3)(i), where a state may consider factors including but not limited to a source's processes and operating procedures, raw materials, physical plant layout, and potential environmental impacts such as increased water pollution, waste disposal, and energy requirements. There are also considerations for economic feasibility of a potential control measure, under 40 CFR 51.1010(c)(3)(ii), where a state may consider capital costs, operating and maintenance costs, and cost effectiveness of the measure. Unless the state has demonstrated that the measure is not technologically or economically feasible, the state shall adopt and implement all potential control measures identified.

Finally, control measures adopted as part of the state's control strategy must be permanent, enforceable as a practical matter, and quantifiable.

In order to be enforceable as a practical matter, the state must adopt into the SIP not only the control measure or emissions limit itself but also appropriate monitoring, recordkeeping, and reporting requirements to ensure compliance with the control measure.

Without appropriate monitoring, recordkeeping, and reporting requirements, violations of the control measure could go undetected.

Control measures must be incorporated by reference into the regulatory portion of the SIP (52.70(c) and (d)) with appropriate monitoring and reporting requirements.

See

CAA section 110(a)(2)(A); 42 U.S.C. 7410(a)(2)(A); 81 FR 58010, August 24, 2016, at pp. 58046-47; 57 FR 13498, April 16, 1992, at pp.13567-68.

81 FR 58010, August 24, 2016, at pp. 58046-47; 57 FR 13498, April 16, 1992, at pp. 13567-68; 67 FR 22168, May 2, 2002, at p. 22170; 80 FR 33840, June 12, 2015, at pp. 33843, 33865;

Montana Sulphur & Chemical Co.

EPA,

666 F.3d 1174, at pp. 1189-1190 (9th Cir. 2012).

67 FR 22168, May 2, 2022, at p. 22170;

Montana Sulphur & Chemical Co.

EPA,

666 F.3d 1174, at pp. 1189-1190 (9th Cir. 2012).

2. Summary of the EPA's Prior Rulemaking Regarding the Control Strategy

On December 5, 2023, the EPA finalized an approval in part and disapproval in part of the BACM requirements for the Fairbanks PM

2.5

Nonattainment Area. The EPA's action for each emissions source category is described in the following paragraphs.

a. Alaska's Identification and Adoption of BACM for Home Heating and Other Area Sources

i. Solid Fuel-Burning

The EPA approved in part and disapproved in part Alaska's analysis and adoption of control measures for this source category as meeting the BACM requirements for PM

2.5

and SO

emissions.

The EPA approved Alaska's analysis that found no NH

-specific emissions controls for this source category. The EPA also previously approved as SIP strengthening and federally enforceable many of the control measures submitted as part of the Fairbanks Serious Plan and prior SIP submissions in 2018 as part of a separate action (86 FR 52997, September 24, 2021).

88 FR 84626, December 5, 2023, at p. 84674.

Alaska identified a number of solid fuel-burning control measures that have been adopted by other states and local authorities to identify the full range of potential BACM/BACT measures for this source category. This analysis took into account technical and economic feasibility and other considerations included in the PM

2.5

SIP Requirements Rule.

Alaska's two-stage Solid Fuel-Burning Appliance Curtailment Program, included in the Fairbanks Emergency Episode Plan, adopts air quality thresholds that are at least as stringent as comparable curtailment programs in Idaho, Utah, and California. Alaska accounted for the differences in natural gas availability, seasonal climate conditions, and wood stove change-out incentives in establishing the two-stage thresholds at 20 µg/m

(Stage 1) and 30 µg/m

(Stage 2), respectively. Alaska also had an advisory level set at 15 µg/m

as part of the curtailment program. Alaska placed further limitations on the “No Other Adequate Source of Heat” (NOASH) waiver (available to households as a temporary waiver from certain curtailment requirements), limiting applicability to those that have economic needs based on objective criteria and limiting the number of years NOASH waivers are available. Therefore, the EPA approved the Solid Fuel-Burning Appliance Curtailment Program and associated updates to the NOASH waivers and temporary exemption as BACM for the solid-fuel burning source category (

i.e.,

Alaska state regulations 18 AAC 50.075 (e)(3), (f)(2)) for PM

2.5

and SO

emissions.

88 FR 84626, December 5, 2023, at pp. 84699, 84673-84675.

Alaska identified and evaluated as BACM the heating device performance standards adopted previously by Missoula County, Montana. Alaska adopted a regulation modeled after the rule in Missoula County. Under 18 AAC 50.077(c), Alaska's regulations require that wood stoves meet emissions standards that are more stringent than the EPA's New Source Performance Standards (NSPS) requirement for residential wood heaters at 40 CFR part 60 and also include one-hour testing requirements to ensure only the lowest-emitting wood stoves are allowed to be sold and installed in the nonattainment area. The EPA approved these measures as BACM for the solid-fuel burning source category (

i.e.,

18 AAC 50.077 (a-j)) for PM

2.5

and SO

emissions.

Id.

Alaska's regulation 18 AAC 50.075(f), applicable to the Fairbanks PM

2.5

Nonattainment Area, prohibits the operation of a solid fuel-fired heating device emissions when visible emissions exceed 20 percent opacity for more than six minutes in any one hour, except during the first 15 minutes after initial firing of the device, when the opacity limit must be less than 50 percent. The rule also prohibits visible emissions from crossing property lines. These opacity limits provide a visual indicator for the proper operation of a solid-fuel heating device. The EPA approved this measure as BACM.

Id.

The EPA approved as BACM the additional removal or render inoperable

restrictions placed on non-certified EPA wood stoves, non-pellet outdoor hydronic heaters, coal-fired heating devices, and EPA-certified wood stoves greater than 25 years-old meet BACM requirements for PM

2.5

and SO

emissions.

These devices are to be removed or rendered inoperable by December 31, 2024, or if a building or residence with such a device is sold prior to that date (or if a wood-fired heating device is 25 years old prior to that date). These include Alaska state regulations 18 AAC 50.077 (l-m). The EPA approved the other solid-fuel burning regulations adopted by Alaska, including device registration under 18 AAC 50.077(h) and dry wood requirements for wood sellers 18 AAC 50.076, which are at least as stringent as similar regulations adopted by other states and local authorities, and therefore represent BACM for PM

2.5

and SO

emissions for the solid-fuel burning source category.

These include Alaska state regulations 18 AAC 50.076 (d-e), (g), (j-l).

Id.

However, the EPA partially disapproved as BACM Alaska's measures regarding dry wood seller requirements and coal-fired heating devices.

The EPA recommended Alaska revise 18 AAC 50.076(k)(3) to require a specific frequency wood sellers are required to measure the moisture content of the seller's wood stock. Likewise, the EPA also recommended Alaska revise the regulations at 18 AAC 50.079(d), (e) and (f) to remove (or revise to BACM and BACT-level stringency) the testing exemption in (d), remove or properly bound the waiver provision in (e), and add requirements to verify compliance with the requirement for the owner and operator to render the device inoperative.

88 FR 84626, December 5, 2023, at pp. 84670, 84675-76.

ii. Residential and Commercial Fuel Oil Combustion

Alaska adopted the regulation at 18 AAC 50.078(b) that imposed a limit of 1,000 parts per million sulfur (diesel no. 1) for residential and commercial heating. This was a switch from diesel no. 2 (approximately 2,000 parts per million sulfur) to diesel no. 1. Alaska also evaluated the potential for adopting ULSD for fuel oil combustion, but the State determined that this measure is economically infeasible. The EPA approved 18 AAC 50.078(b) as meeting the SO

BACM and BACT requirements for the space heating area source category.

88 FR 84626, December 5, 2023, at p. 84674-75.

iii. Small Commercial Area Sources

The EPA approved Alaska's determination that there were no incinerators in the nonattainment area. Therefore, Alaska need not identify, adopt, or implement controls for the incinerator source category. The EPA also approved Alaska's BACM infeasibility demonstrations for add-on control for charbroilers and restrictions on used oil burners. By extension, the EPA approved 18 AAC 50.055 as BACM/BACT for the charbroiler source category.

Id.

However, the EPA disapproved Alaska's BACM requirements for coffee roasters. The EPA cited a number of deficiencies with Alaska's adopted control measure for coffee roasters at 18 AAC 50.078(d).

88 FR 84626, December 5, 2023, at p. 84676;

See also

81 FR 58010, August 24, 2016, at p. 58047.

iv. Weatherization and Energy Efficiency

The EPA disapproved Alaska's BACM analysis with respect to potential energy efficiency and weatherization measures. The State provided a number of reasons for declining to adopt and implement any such measures, each of which the EPA rejected as bases to not adopt weatherization and energy efficiency measures.

88 FR 84626, December 5, 2023, at pp. 84641, 84676;

See also

81 FR 58010, August 24, 2016, at p. p. 58085.

v. Emissions From Mobile Sources

The EPA approved Alaska's rejection of the CARB vehicle standards as economically infeasible. The EPA likewise finalized approval of Alaska's rejection of school bus retrofits, road paving, and controls on road sanding and salting as technologically infeasible. The EPA approved Alaska's rejection of a motor vehicle inspection and maintenance (I/M) program. The EPA approved Alaska's determination that no NH

-specific emissions controls exist for this source category.

88 FR 84626, December 5, 2023, at p 84675-76.

The EPA approved Alaska's rejection of other transportation measures as either technologically infeasible (HOV lanes) or economically infeasible (traffic flow improvements, diesel retrofit projects, and ridesharing programs).

Id.

However, the EPA approved in part and disapproved in part Alaska's rejection of vehicle idling restrictions and other transportation measures.

Specifically, the EPA approved Alaska's rejection of vehicle idling restrictions for heavy-duty diesel vehicles as economically infeasible. However, the EPA disapproved Alaska's rejection of vehicle idling restrictions for light-duty vehicles at schools and commercial establishments. The EPA determined that Alaska had not demonstrated that vehicle anti-idling restrictions for light-duty passenger vehicles are infeasible.

Id.

b. Alaska's Identification and Adoption of BACT for Major Stationary Sources

In its December 5, 2023, action, the EPA partially approved and partially disapproved the Fairbanks Serious Plan as meeting the BACM and BACT requirements for major stationary sources.

i. Chena Power Plant

The EPA partially approved and partially disapproved Alaska's BACM/BACT evaluation for the Chena Power Plant. The EPA partially disapproved the BACT determination because Alaska did not identify, adopt, and implement BACT for PM

2.5

and SO

. The EPA approved Alaska's BACT analysis for NH

emissions controls for the Chena Power Plant.

88 FR 84626, December 5, 2023, at pp. 84670-71, 84675-76.

ii. Doyon-Fort Wainwright Central Heating and Power Plant

The EPA partially approved and partially disapproved Alaska's BACM/BACT determinations for PM

2.5

controls for each of the emission sources at Doyon-Fort Wainwright Central Heating and Power Plant. The EPA partially approved the BACT determinations because Alaska's BACT findings for PM

2.5

(embodied in State Air Quality Control Plan, Vol. II, section III.D.7.7, Tables 7.7-11 and 7.7-13 and section III.D.7.7.8.3.4) were consistent with CAA section 189(b) and 40 CFR 51.1010(a). The EPA partially disapproved the BACT determinations because the Fairbanks Serious Plan and initial Fairbanks 189(d) Plan lacked provisions necessary to ensure the BACT determinations for PM

2.5

are enforceable as a practical matter as required by CAA sections 110(a)(2)(A) and 172(c)(7).

Id.

On September 25, 2023, Alaska withdrew its SO

BACT determinations for Doyon-Fort Wainwright Central Heating and Power Plant. Therefore, the EPA finalized disapproval of Alaska's SO

BACT determinations because the

Fairbanks Serious Plan and initial Fairbanks 189(d) Plan did not identify, adopt, and implement BACT for SO

at the Doyon-Fort Wainwright Central Heating and Power Plant. The EPA approved Alaska's analysis that found no NH

-specific emissions controls for the sources at this facility.

Id.

iii. University of Alaska Fairbanks Campus Power Plant

The EPA disapproved Alaska's BACM/BACT determination for PM

2.5

controls for the Small Diesel-Fired Engines (EU IDs 23, 26, and 27). The EPA partially approved and partially disapproved the Alaska's BACT determinations for PM

2.5

controls for the remaining emission units. The EPA partially approved the PM

2.5

BACT determinations because Alaska's BACT determinations embodied in State Air Quality Control Plan, Vol. II, section III.D.7.7, Table 7.7-16 and section III.D.7.7.8.6 were consistent with CAA section 189(b) and 40 CFR 51.1010(a). The EPA partially disapproved Alaska's BACT determinations because the Fairbanks Serious Plan and initial Fairbanks 189(d) Plan lacked provisions necessary to ensure the BACT determinations are enforceable as a practical matter as required by CAA sections 110(a)(2)(A) and 172(c)(7).

Id.

at p. 84657

On September 25, 2023, Alaska withdrew its SO

BACT determinations for the Fairbanks Campus Power Plant. Therefore, the EPA disapproved Alaska's SO

BACT determinations because the Fairbanks Serious Plan and initial Fairbanks 189(d) Plan did not identify, adopt, and implement BACT for SO

at the Fairbanks Campus Power Plant. The EPA approved Alaska's analysis that found no NH

-specific emissions controls for the sources at this facility.

Id.

at pp. 84670-71, 84675-76.

iv. Zehnder Power Plant

The EPA partially approved and partially disapproved Alaska's BACM/BACT provisions for PM

2.5

controls for all emission units at the Zehnder Power Plant. The EPA partially approved the PM

2.5

BACT determination because Alaska's BACT determinations embodied in the State Air Quality Control Plan, Vol. II, section III.D.7.7, Table 7.7-14 and Appendix III.D.7.7.8.4 are consistent with CAA section 189(b) and 40 CFR 51.1010(a). The EPA partially disapproved Alaska's PM

2.5

BACT determinations because the Fairbanks Serious Plan and initial Fairbanks 189(d) Plan lacked provisions necessary to ensure the PM

2.5

BACT determinations are enforceable as a practical matter as required by CAA sections 110(a)(2)(A) and 172(c)(7).

Id.

On September 25, 2023, Alaska withdrew its SO

BACT determinations for the Zehnder Power Plant. Therefore, the EPA partially disapproved the SO

BACT determinations because Fairbanks Serious Plan and initial Fairbanks 189(d) Plan did not identify, adopt, and implement BACT for SO

at the Zehnder Power Plant. The EPA approved Alaska's analysis that found no NH

-specific emissions controls for the sources at this facility.

Id.

v. North Pole Power Plant

The EPA partially approved and partially disapproved Alaska's BACM/BACT provisions for PM

2.5

controls for all emission units at the North Pole Power Plant. The EPA partially approved Alaska's PM

2.5

BACT determinations because these findings embodied in State Air Quality Control Plan, Vol. II, section III.D.7.7, Table 7.7-14 and Appendix III.D.7.7.8.5 are consistent with CAA section 189(b) and 40 CFR 51.1010(a). The EPA partially disapproved Alaska's PM

2.5

BACT determinations because the Fairbanks Serious Plan and initial Fairbanks 189(d) Plan lacked provisions necessary to ensure the BACT determinations are enforceable as a practical matter as required by CAA sections 110(a)(2)(A) and 172(c)(7).

Id.

On September 25, 2023, Alaska withdrew its SO

BACT determinations for the North Pole Power Plant. Therefore, the EPA partially disapproved Alaska's SO

BACT determinations because the Fairbanks Serious Plan and initial Fairbanks 189(d) Plan did not identify, adopt, and implement BACT for SO

at the North Pole Power Plant. The EPA approved Alaska's analysis that found no NH

-specific emissions controls for the sources at this facility.

c. NH

Emissions Controls

With respect to NH

controls, for residential and commercial area sources, the EPA approved certain measures as meeting the BACM/BACT requirement for NH

emissions. In other cases, the EPA approved Alaska's BACM/BACT analysis that concluded there are no NH

-specific controls for the emission source categories contributing to PM

2.5

formation in the Fairbanks PM

2.5

Nonattainment Area, but that there are likely to be NH

emissions co-benefits of measures designed to reduce emissions of direct PM

2.5

Id.

3. Summary of the State's Submission and the EPA's Evaluation and Proposed Action Regarding the Control Strategy

a. Updates to the Identification and Adoption of BACM

Below is a summary of the regulations and SIP revisions adopted as part of the Fairbanks Revised 189(d) Plan, organized by source category, responding to EPA's December 5, 2023, disapproval.

State Air Quality Control Plan, Vol. II, section III.D.7.7.13.

i. Solid-Fuel Burning

Alaska revised the dry wood seller measure, adopted as regulation 18 AAC 50.076(k)(3), by setting a frequency at monthly intervals to measure the moisture content. Alaska also revised regulation 18 AAC 50.076(k)(1) by improving the labeling to indicate “dry wood.”

Regarding the EPA's disapproval of coal-fired heating device requirements, Alaska revised 18 AAC 50.079 by lowering the emissions threshold to test out of the mandatory removal requirements in 18 AAC 50.079(d) from 18 grams per hour to 0.10 pounds per million British thermal units (Btu) which is equivalent to the pellet hydronic heater limit in 18 AAC 50.077. Alaska amended 18 AAC 50.079(d) to require a testing protocol be approved by the department prior to any test attempting to exempt a coal device from the mandatory removal requirement. Alaska revised 18 AAC 50.079(e) limit the duration of the waiver to one calendar year.

The EPA previously approved 18 AAC 50.079(f), which requires the owner of a coal-fired heating device to render it inoperable not later than December 31, 2024. As a consequence of Alaska's revisions to 18 AAC 50.079(f), the latest an individual with a coal-fired heating device could remove that device is December 31, 2025—provided the individual meets the eligibility requirements in 18 AAC 50.079(e). Alaska stated that 18 AAC 50.079(f) is revised for clarity by adding section (3), which requires coal-fired heating devices to be rendered inoperable after the expiration of a waiver granted under subsection (e) of 18 AAC 50.079. Alaska stated that newly adopted section 18 AAC 50.079(h) requires documentation on the removal and rendering of the device inoperable and submitting an affidavit that the coal stove will not be

reinstalled in the Fairbanks PM

2.5

Nonattainment Area.

Based on these updates, the EPA proposes to approve the submitted revisions to 18 AAC 50.076 and 18 AAC 50.079 as meeting the requirements of CAA sections 110(a)(2)(A), 172(c)(7), and 189(b) and 40 CFR 51.1010(a). Accordingly, the EPA proposes to determine that the Fairbanks Revised 189(d) Plan rectifies the disapproved portions of the Fairbanks Serious Plan and initial Fairbanks 189(d) Plan for the solid fuel-burning source category.

ii. Residential and Commercial Fuel Oil Combustion

In the EPA's December 5, 2023, rule, the EPA approved as BACM Alaska's regulation under 18 AAC 50.078(b) that imposes a limit of 1,000 parts per million sulfur content in fuel limit (diesel no. 1) for residential and commercial heating.

This was a switch from diesel no. 2 (approximately 2,000 parts per million sulfur content in fuel limit) to diesel no. 1. The EPA agreed with Alaska's demonstration that further strengthening this requirement to 15 parts per million sulfur (

i.e.,

Ultra-low sulfur diesel) was economically infeasible.

88 FR 84626, December 5, 2023, at pp. 84669, 84674.

iii. Small Commercial Area Sources

Alaska revised its regulations for coffee roasters, under 18 AAC 50.078(d). These updated regulations clarify the specific emission limit required for this source category and ensures the limit is enforceable as a practical matter. The EPA proposes to approve the submitted revisions to 18 AAC 50.078(d) as meeting the requirements of CAA section 110(a)(2), 172(c)(7), and 189(b) and 40 CFR 51.1010(a) for this source category. Accordingly, the EPA proposes to determine that the Fairbanks Revised 189(d) Plan rectifies the disapproved portions of the Fairbanks Serious Plan and initial Fairbanks 189(d) Plan for coffee roasters.

iv. Energy Efficiency and Weatherization

To address the EPA's disapproval, Alaska reviewed weatherization and energy efficiency measures adopted by other jurisdictions. Based on this review, Alaska adopted a weatherization and energy efficiency measure at 18 AAC 50.081. The measure mandates that a building owner have an energy rating completed on the building before listing it for sale. The rule requires that the seller provide the energy rating report to the buyer. Alaska also committed to a robust advertising and education program that includes best practices to improve efficiency in an arctic environment and available economic and practical mechanisms that can assist homeowners in improving both efficiency and regulatory compliance. Alaska asserted that these components will improve the compliance rate for other control measures, including the solid fuel-fired heating device curtailment program and the requirement to remove older, uncertified heating appliances. Alaska noted that any improvements identified by the energy rater will be voluntary.

Alaska evaluated adopting building energy efficiency codes or mandatory weatherization requirements and dismissed them as technologically infeasible. According to Alaska, there is a lack of technical expertise and resources to implement (lack of energy auditors and training resources), enforce, and ensure code compliance. Alaska further contended that the earliest date Alaska can implement building codes exceeded not only the statutory requirement for the implementation of BACM by December 31, 2024, but also beyond the 2027 attainment date identified in the Fairbanks Revised 189(d) Plan.

The EPA proposes to approve the submitted revisions to 18 AAC 50.081 as meeting the requirements of CAA sections 110(a)(2), 172(c)(7), and 189(b) and 40 CFR 51.1010(a) with respect to weatherization and energy efficiency. Accordingly, the EPA proposes to determine that the Fairbanks Revised 189(d) Plan rectifies the disapproved portions of the Fairbanks Serious Plan and initial Fairbanks 189(d) Plan for weatherization and energy efficiency.

v. Emissions From Mobile Sources

The EPA previously approved as part of Fairbanks Moderate Plan, a requirement that businesses with 275 or more parking spaces provide power to electrical outlets at temperatures of 20 degrees Fahrenheit or lower for engine block heaters.

100

In addition, Alaska continues to install new plug-ins throughout the Fairbanks PM

2.5

Nonattainment Area.

101

100

82 FR 42457, September 8, 2017; State Air Quality Control Plan, Vol. III, Appendix III.D.5.7, adopted December 24, 2014, at p. 43; State Air Quality Control Plan, Vol. III, Appendix III.D.5.12, adopted December 24, 2014, at p. 43.

101

There are nearly 10,000 plug-ins available in the nonattainment area. See State Air Quality Control Plan, Appendix III.D.7.7 (adopted November 19, 2019), at p. 17.

As part of the Fairbanks Revised 189(d) Plan, Alaska re-evaluated anti-idling for light-duty vehicles as a potential control measure. Alaska provided additional analysis demonstrating that such a measure is technologically and economically infeasible in the Fairbanks PM

2.5

Nonattainment Area. In particular, Alaska noted that other jurisdictions that implement this measure include a temperature threshold, below which restrictions do not apply. These temperature cut offs range from 40 degrees Fahrenheit to 10 degrees Fahrenheit. These thresholds are intended to protect human health and safety.

Accordingly, Alaska evaluated implementing idling restrictions during the winter months of October through March at temperatures above 21 degrees Fahrenheit. Given that episodic emissions contributing to PM

2.5

concentrations occur at sub-zero temperatures, Alaska's evaluation indicates that the measure would not achieve any emissions reductions.

The EPA notes that in order to achieve emissions reductions in the extreme Fairbanks environment, Alaska would have to prohibit idling regardless of ambient temperature, which presents unacceptable risks to human health. In light of these concerns, rather than regulate the vehicle users, Alaska requires owners of parking areas to provide electricity for engine-block heaters. Alaska and the EPA have previously determined that expanding plug-in availability is economically infeasible.

102

Therefore, the EPA proposes to approve Alaska's current plug-in program as meeting BACM and BACT requirements for light-duty vehicles.

102

88 FR 84626, December 5, 2023, at pp. 84649, 84652 (determining that anti-idling restrictions on heavy-duty vehicles had a cost effectiveness of over $400,000 per ton of SO

reduced).

Accordingly, the EPA proposes to determine that Alaska has rectified the EPA's December 5, 2023, disapproval of the Fairbanks Serious Plan and initial Fairbanks 189(d) Plan with respect to control strategy requirements for mobile sources.

b. Alaska's Identification and Adoption of BACT for Major Stationary Sources

Alaska submitted revisions to its BACM/BACT determinations for the five major stationary sources in the Fairbanks PM

2.5

Nonattainment Area, as described in the following paragraphs.

103

Alaska also submitted permits for each of the five major

stationary sources that adopt and implement BACT for direct PM

2.5

103

State Air Quality Control Plan Vol. II, Appendix III.D.7.7 (adopted November 5, 2024).

i. Chena Power Plant

Chena Power Plant is an existing stationary source owned and operated by Aurora Energy, LLC, which consists of four existing coal-fired boilers: three 76 million British Thermal Units (MMBtu) per hour overfeed traveling grate stoker type boilers and one 269 MMBtu per hour spreader-stoker type boiler that burn coal to produce steam for heating and power (497 MMBtu per hour combined). The source also includes a coal preparation plant, coal stockpile, ash vacuum pump exhaust, and truck bay ash loadout.

Alaska revised its State Air Quality Control Plan to include its BACT determinations for PM

2.5

and SO

for each of the emission units at the Chena Power Plant.

104

We note that Alaska removed its BACT evaluation and determinations for NO

because the EPA approved a comprehensive NO

precursor demonstration. Alaska also submitted conditions from Air Quality Control Minor Permit AQ0315MSS02 Revision 1 for the Aurora Energy, LLC—Chena Power Plant (Aurora Permit). The Aurora Permit conditions include enforceable PM

2.5

BACT emissions limitations for the emission units at the Chena Power Plant comprised of numerical emissions limits and work practice standards and associated monitoring, recordkeeping and reporting requirements. The permits are included in the docket for this action.

105

104

See

State Air Quality Control Plan, Vol. III, Appendix III.D.7.7-164. Note, Alaska's prior SIP submissions only evaluated BACT for the coal-fired boilers.

105

See

State Air Quality Control Plan, Vol. III, Appendix III.D.7.7-187.

The EPA previously reviewed Alaska's BACM/BACT evaluation for the Chena Power Plant.

106

Alaska has since clarified that PM

2.5

BACT for the coal-fired boilers is operating and maintaining fabric filters (full steam baghouse) during operation.

107

Thus, in this action, the EPA is proposing to approve Alaska's PM

2.5

BACT determinations for the Chena Power Plant, the submitted revisions to State Air Quality Control Plan, Vol. III, Appendix III.D.7.7, related to direct PM

2.5

emissions and the submitted Aurora Permit conditions

108

as satisfying CAA section 189(b) and 40 CFR 51.1010.

106

See

Hedgpeth and Sorrels. (August 24, 2022).

Review of Best Available Control Technology analyses submitted for the Aurora Energy, LLC Chena Power Plant as part of the Fairbanks PM

2.5

Nonattainment SIP.

U.S. Environmental Protection Agency, Region 10, Laboratory Services and Applied Science Division, EPA-R10-OAR-2022-0115.

107

See

State Air Quality Control Plan, Vol. III, Appendix III.D.7.7-173.

108

See

section III.A of this preamble for the specific permit conditions proposed for approval.

The EPA is not proposing to take action on Alaska's SO

BACT determinations in State Air Quality Control Plan, Vol. III, Appendix III.D.7.7, at this time. As discussed in the preceding paragraphs, the EPA is proposing to approve Alaska's SO

precursor demonstration for major stationary sources. If approved, Alaska will not be required to identify, adopt, or implement SO

BACT for the Chena Power Plant. If the EPA does not finalize approval of the SO

precursor demonstration, then the EPA will propose action on Alaska's SO

BACT determinations in a separate, future action.

ii. Doyon-Fort Wainwright Central Heating and Power Plant

Fort Wainwright is an existing U.S. Army installation. Emission units located within the military installation include units such as boilers and generators that are owned and operated by the U.S. Army Garrison Alaska (referred to as FWA). The Central Heating and Power Plant (CHPP), also located within the installation footprint, is owned and operated by Doyon Utilities, LLC (DU), the regional Alaska Native corporation for Interior Alaska. The two entities, DU and FWA, comprise a single stationary source operating under two permits.

The CHPP is comprised of six spreader-stoker type coal-fired boilers, each rated at 230 MMBtu per hour, that burn coal to produce steam for stationary source-wide heating and power. In addition to the CHPP, the source contains emission units comprised of small and large emergency engines, fire pumps, and generators, diesel-fired boilers, and material handling equipment. Alaska's BACM/BACT analysis in the Fairbanks Serious Plan for the stationary source evaluated potential controls to reduce NO

, PM

2.5

, and SO

emissions from each of these emissions units at the stationary source.

109

Alaska evaluated potential NO

controls for each emission unit, but because Alaska determined and the EPA approved that NO

emissions are not significant for PM

2.5

formation in the Fairbanks PM

2.5

Nonattainment Area, Alaska does not plan to require implementation of BACT for NO

. See 88 FR 84626, December 5, 2023. Thus, EPA is not discussing Alaska's BACT analysis for NO

here.

As part of the Fairbanks Revised 189(d) Plan, Alaska revised its Air Quality Control Plan sections related to the Doyon-Fort Wainwright CHPP to reflect new engines powering lift pumps and generators, correct typographical errors, improve clarity, and to include updated SO

BACT determinations.

110

With respect to the new engines, all are EPA-certified engines ranging in size from 74 horsepower to 324 horsepower. Alaska updated its PM

2.5

BACT determinations for these new engines. Alaska removed its BACT evaluation and determinations for NO

because the EPA approved a comprehensive NO

precursor demonstration.

110

See

State Air Quality Control Plan, Vol. III, Appendix III.D.7.7-202.

Alaska also submitted conditions from two Air Quality Control Minor Permits: AQ0236MSS03 Revision 2 (U.S. Army Garrison—USAG Alaska Fort Wainwright) and AQ1121MSS04 Revision 1 (Doyon Utilities, LLC—Fort Wainwright) (collectively referred to as the Fort Wainwright Permits). The Fort Wainwright Permits include enforceable PM

2.5

BACT emissions limitations for the emission units at Fort Wainwright comprised of numerical emissions limits and work practice standards and associated monitoring, recordkeeping and reporting requirements. The permits are included in the docket for this action.

111

See

State Air Quality Control Plan, Vol. III, Appendix III.D.7.7-248.

The EPA previously reviewed Alaska's BACM/BACT evaluation for the Doyon-Fort Wainwright Central Heating and Power Plant.

112

In addition to the submitted conditions discussed in this section x.x.ii of this preamble, Alaska's updated BACT determination clarified the maintenance and testing requirements for the diesel-fired boilers and added enclosed conveying system requirements.

113

The EPA previously approved Alaska's BACT determinations for older pump engines and generator engines. Alaska updated its BACT determinations and associated permit limits to reflect grams per hour emission limits appropriate to the size and model year of the engine. Alaska also imposed limits on the hours of operations of these engines. Thus, in this action, the EPA is proposing to approve Alaska's updated PM

2.5

BACT determinations for the emissions units

at Doyon-Fort Wainwright CHPP,

114

the submitted revisions to State Air Quality Control Plan, Vol. III, Appendix III.D.7.7 related to direct PM

2.5

emissions from the Doyon-Fort Wainwright CHPP,

115

and the submitted conditions from the Fort Wainwright Permits

116

as satisfying CAA section 189(b) and 40 CFR 51.1010.

112

See

Hedgpeth, Z. (August 24, 2022).

Review of Best Available Control Technology analyses submitted for Fort Wainwright-US Army Garrison Alaska (FWA) and Doyon Utilities, LLC (DU) as part of the Fairbanks PM

2.5

Nonattainment SIP.

U.S. Environmental Protection Agency, Region 10, Laboratory Services and Applied Science Division, EPA-R10-OAR-2022-0115.

113

See State Air Quality Control Plan, Vol. III, Appendix III.D.7.7-217; State Air Quality Control Plan, Vol. III, Appendix III.D.7.7-225.

114

Industrial coal-fired boilers; diesel-fired boilers; diesel-fired engines, fire pumps, and generators; and material handling equipment.

115

The EPA is not proposing to approve the NO

related emissions limits as meeting BACT for NO

. For some emission units, Alaska imposed NO

emissions limits as surrogates for direct PM

2.5

emissions.

116

See

section III.A of this preamble for the specific permit conditions proposed to be approved.

The EPA is not proposing to take action on Alaska's SO

BACT determinations in State Air Quality Control Plan, Vol. III, Appendix III.D.7.7 at this time for the same reasons discussed in the preceding paragraphs regarding the Chena Power Plant. If the EPA does not finalize approval of the SO

precursor demonstration, then the EPA will propose action on Alaska's SO

BACT determinations in a separate, future action.

iii. University of Alaska Fairbanks Campus Power Plant

The Fairbanks Campus Power Plant is an existing stationary source owned and operated by the University of Alaska Fairbanks, which consists of two coal-fired boilers installed in 1962 that were later replaced by a circulating fluidized bed (CFB) dual fuel-fired boiler (coal and biomass) rated at 295.6 MMBtu per hour. Other emission units at the source include a backup diesel generator, diesel-fired boilers, engines, and a coal handling system for the new dual-fuel fired boiler.

In the Fairbanks Revised 189(d) Plan, Alaska updated its Air Quality Control Plan regarding the Fairbanks Campus Power Plant to reflect permanently removed emission units, add new diesel boilers and engines, update the PM

2.5

BACT determinations for small diesel-fired boilers and large and small engines, correct typographical errors, and improve clarity.

117

Alaska also added updated SO

BACT determinations for the Fairbanks Campus Power Plant.

117

See

State Air Quality Control Plan, Vol. III, Appendix III.D.7.7-356.

With respect to the small diesel-fired boilers (EUs 17 through 22), Alaska updated its BACT determination for PM

2.5

to consist of a partial limit on hours of operation, an emission limit of 0.016 lb/MMBtu,

118

compliance with 40 CFR part 63, subpart JJJJJJ, and work practice standards. Alaska evaluated whether installation of a scrubber was feasible for these boilers and determined that it was economically infeasible.

119

Alaska noted that taking into consideration the enforceable limit on operation, the combined potential to emit of PM

2.5

for the six boilers is two tons per year.

118

Alaska noted that it previously selected a 0.012 lb/MMBtu limit erroneously. This limit is associated with industrial boilers while the boilers at the Fairbanks Campus Power Plant are commercial boilers.

119

State Air Quality Control Plan, Vol. III, Appendix III.D.7.7-369.

With respect to large diesel fired engines (EUs 8 and 35) and small diesel fired engines (EUs 24, 26, 27, 29, and 34),

120

Alaska reevaluated the feasibility of add-on PM

2.5

controls, namely a diesel particulate filter (DPF).

121

EUs 24, 29, and 34 are limited to 100 hours per year of non-emergency operation, so additional BACT controls were not evaluated for these units. Alaska determined that a DPF is not technologically feasible for EU 8 due to an unacceptable increase in back pressure. Alaska determined that DPFs were technologically feasible for the other engines, but Alaska determined that the high cost per unit of emissions reductions rendered them economically infeasible. Updating the cost-effectiveness analysis to reflect comments from the EPA's Technical Support Document,

122

Alaska determined that the cost-effectiveness ranged from over $17,000 at EU 26 to over $20,000 per ton of PM

2.5

reduced at EU 27. Alaska stated that EU 35 has potential PM

2.5

emissions of 0.03 tons per year, which is an order of magnitude lower than the two other diesel engines, EUs 26 and 27. Therefore, Alaska did not perform a cost analysis for installing and operating a DPF on EU 35 as it would have an even higher cost per ton estimate than EUs 26 and 27. Furthermore, Alaska noted that EU 35 is limited to 100 hours per calendar year of non-emergency operation and required to combust ULSD under the existing Federal NSPS Subpart IIII requirements.

123

120

In comments, the University of Alaska Fairbanks clarified that EU 23 has been permanently removed from service and are no longer permitted EUs at the facility. See Comments on Proposed Rule—Air Plan Partial Approval and Partial Disapproval; AK, Fairbanks North Star Borough; 2006 24-Hour PM

2.5

Serious Area and 189(d) Plan, at p. 9, Docket ID No. EPA-R10-OAR-2022-0115.

121

State Air Quality Control Plan, Vol. III, Appendix III.D.7.7-372.

122

See

Hedgpeth and Sorrels. (August 24, 2022).

Review of Best Available Control Technology analyses submitted for the University of Alaska, Fairbanks as part of the Fairbanks PM

2.5

Nonattainment SIP,

p.15. U.S. Environmental Protection Agency, Region 10, Laboratory Services and Applied Science Division, EPA-R10-OAR-2022-0115.

123

State Air Quality Control Plan, Vol. III, Appendix III.D.7.7-374.

Alaska removed its BACT evaluation and determinations for NO

because the EPA approved a comprehensive NO

precursor demonstration.

124

88 FR 84626, December 5, 2023.

Alaska also submitted conditions from Air Quality Control Minor Permit AQ0316MSS08 Revision 1 (University of Alaska Fairbanks (UAF)—University of Alaska Fairbanks Campus) (UAF Permit). The UAF Permit conditions include enforceable PM

2.5

BACT emissions limitations comprised of numerical emissions limits and work practice standards with associated monitoring, recordkeeping, and reporting. The permits are included in the docket for this action.

125

See

State Air Quality Control Plan, Vol. III, Appendix III.D.7.7-414.

The EPA previously reviewed Alaska's BACT evaluation for the Fairbanks Campus Power Plant.

126

In this action, the EPA is proposing to approve Alaska's updated PM

2.5

BACT determinations for the small diesel-fired boilers (EUs 17 through 22), large diesel-fired engines (EUs 8 and 35), and small diesel-fired engines (EUs 24, 26, 27, 29, and 34) at the Fairbanks Campus Power Plant. The EPA previously approved Alaska's PM

2.5

BACT determinations for EUs 8, 17-19, 24, and 29. Alaska's updates are consistent with these past approvals. With respect to EUs 26, 27, and 35, the EPA proposes to approve Alaska's economic infeasibility demonstrations for DPFs. The EPA is proposing to approve Alaska's PM

2.5

BACT emissions limits for small diesel-fired boilers (EUs 17 through 22), large diesel-fired engines (EUs 8 and 35), and small diesel-fired engines (EUs 24, 26, 27, 29, and 34) at the Fairbanks Campus Power Plant, which consist of numerical emissions limits, limits on operation, fuel requirements, and work practice standards.

126

See

Hedgpeth and Sorrels. (August 24, 2022).

Review of Best Available Control Technology analyses submitted for the University of Alaska, Fairbanks as part of the Fairbanks PM

2.5

Nonattainment SIP.

U.S. Environmental Protection Agency, Region 10, Laboratory Services and Applied Science Division, EPA-R10-OAR-2022-0115.

Therefore, the EPA proposes to approve the submitted revisions to State Air Quality Control Plan, Vol. III, Appendix III.D.7.7 related to direct PM

2.5

emissions and NO

emissions

127

from the Fairbanks Campus Power Plant

and the submitted conditions from the UAF Permit

128

as satisfying CAA section 189(b) and 40 CFR 51.1010.

127

The EPA is not proposing to approve the NO

related emissions limits as meeting BACT for NO

. For some emission units, Alaska imposed NO

emissions limits as surrogates for direct PM

2.5

emissions.

128

See

section III.A of this preamble for the specific permit conditions proposed to be approved.

The EPA is not proposing to take action on Alaska's SO

precursor demonstration, then the EPA will propose action on Alaska's SO

BACT determinations in a separate, future action.

iv. Zehnder Facility

The Zehnder Facility (Zehnder) is an electric generating facility that combusts distillate fuel in combustion turbines to provide power to the Golden Valley Electric Association (GVEA) grid. The power plant contains two fuel oil-fired simple cycle gas combustion turbines (each unit rated at 268 MMBtu per hour) and two diesel-fired generators (electro-motive diesels) used for emergency power and to serve as black start engines for the GVEA generation system. The primary fuel is stored in two 50,000 gallon above-ground storage tanks. Turbine startup fuel and electro-motive diesels primary fuel is stored in a 12,000 gallon above ground storage tank.

In the Fairbanks Revised 189(d) Plan, Alaska revised its Air Quality Control Plan for the Zehnder Facility to correct errors and improve clarity.

129

Alaska also submitted conditions from Air Quality Control Minor Permit AQ0109MSS01 Revision 1 (Golden Valley Electric Association—Zehnder Facility) (Zehnder Permit). The Zehnder Permit contains enforceable PM

2.5

BACT emissions limitations for the emission units at the Zehnder Facility comprised of numerical emissions limits and work practice standards with associated monitoring, recordkeeping, and reporting. The permits are included in the docket for this action.

130

129

State Air Quality Control Plan, Vol. III, Appendix III.D.7.7-316.

130

See

State Air Quality Control Plan, Vol. III, Appendix III.D.7.7-342.

Similar to the small diesel-fired boilers (EUs 17 through 22) at the Fairbanks Campus Power Plant discussed in the preceding paragraphs of section II.C of this preamble, Alaska imposed, in the Fairbanks Serious Plan and Fairbanks 189(d) Plan, an erroneous emissions limit on the small diesel fired boilers at the Zehnder Facility. The revised Air Quality Control Plan and associated conditions in the Zehnder Permit reflect the corrected limit.

131

State Air Quality Control Plan, Vol. III, Appendix III.D.7.7-327.

The EPA previously reviewed Alaska's BACT evaluation for the Zehnder Facility.

132

In EPA's prior analysis, the EPA agreed with Alaska's BACT determinations for PM

2.5

. For the turbines, no technologically feasible add-on control options exist to reduce PM

2.5

emissions. For the emergency generators, the EPA agreed that the limits on annual hours of operation of 100 hours per year or less will result in add-on control equipment such as DPF being cost prohibitive. Further, the EPA stated that similar to the turbines, no technologically feasible add-on control options exist to reduce PM

2.5

emissions from the small diesel and propane fired boilers.

133

132

See

Hedgpeth, Z. (August 24, 2022).

Review of Best Available Control Technology analyses submitted for the Golden Valley Electric Association (GVEA) Zehnder and North Pole Power Plants as part of the Fairbanks PM

2.5

Nonattainment SIP.

U.S. Environmental Protection Agency, Region 10, Laboratory Services and Applied Science Division, EPA-R10-OAR-2022-0115.

133

Id.

at p. 11.

Thus, in this action, the EPA proposes to approve the submitted revisions to State Air Quality Control Plan, Vol. III, Appendix III.D.7.7 related to direct PM

2.5

emissions and NO

134

emissions from Zehnder and the submitted Zehnder Permit conditions as satisfying CAA section 189(b) and 40 CFR 51.1010.

134

The EPA is not proposing to approve the NO

related emissions limits as meeting BACT for NO

. For some emission units, Alaska imposed NO

emissions limits as surrogates for direct PM

2.5

emissions.

The EPA is not proposing to take action on Alaska's SO

precursor demonstration, then the EPA will propose action on Alaska's SO

BACT determinations in a separate, future action.

v. North Pole Power Plant

The North Pole Power Plant is an electric generating facility that combusts distillate fuel in combustion turbines to provide power to the Golden Valley Electric Association (GVEA) grid. The power plant contains two fuel oil-fired simple cycle gas combustion turbines (each unit rated at 672 MMBtu per hour), two fuel oil-fired combined cycle gas combustion turbines (each unit rated at 455 MMBtu per hour), one fuel oil-fired emergency generator, and two propane-fired boilers.

In the Fairbanks Revised 189(d) Plan, Alaska revised its Air Quality Control Plan for the North Pole Power Plant to correct errors and improve clarity.

135

Alaska also submitted conditions from Air Quality Control Minor Permit AQ0110MSS01 Revision 1 (Golden Valley Electric Association—North Pole Power Plant) (NPPP Permit). The NPPP Permit conditions include enforceable PM

2.5

BACT emissions limitations for the emission units at the North Pole Power Plant comprised of numerical emissions limits and work practice standards with associated monitoring, recordkeeping, and reporting. The permits are included in the docket for this action.

136

135

State Air Quality Control Plan, Vol. III, Appendix III.D.7.7-267.

136

See

State Air Quality Control Plan, Vol. III, Appendix III.D.7.7-300.

The EPA previously reviewed Alaska's BACT evaluation for the North Pole Power Plant.

137

Similar to the Zehnder facility discussion in the preceding paragraphs in this section II.C, the EPA agreed with Alaska that no additional PM

2.5

BACT controls are feasible for emissions units at the North Pole Power Plant.

138

Thus, in this action, the EPA proposes to approve the submitted revisions to State Air Quality Control Plan, Vol. III, Appendix III.D.7.7 related to direct PM

2.5

emissions and NO

139

emissions from the North Pole Power Plant and the submitted NPPP Permit conditions

140

as satisfying CAA section 189(b) and 40 CFR 51.1010.

137

See

Hedgpeth, Z. (August 24, 2022).

Review of Best Available Control Technology analyses submitted for the Golden Valley Electric Association (GVEA) Zehnder and North Pole Power Plants as part of the Fairbanks PM

2.5

Nonattainment SIP.

U.S. Environmental Protection Agency, Region 10, Laboratory Services and Applied Science Division, EPA-R10-OAR-2022-0115.

138

Id.

at p. 11.

139

The EPA is not proposing to approve the NO

related emissions limits as meeting BACT for NO

. For some emission units, Alaska imposed NO

emissions limits as surrogates for direct PM

2.5

emissions.

140

See

section III.A of this preamble for the specific permit conditions proposed to be approved.

The EPA is not proposing to take action on Alaska's SO

precursor demonstration, then the EPA will propose action on Alaska's SO

BACT determinations separately.

c. Alaska's Identification and Adoption of Additional Measures and Demonstration of Five Percent Reduction in Emissions Pursuant to CAA Section 189(d)

The Fairbanks Revised 189(d) Plan retained the identification of all sources of direct PM

2.5

emissions and PM

2.5

plan precursors, identification of all potential controls to reduce direct PM

2.5

emissions and PM

2.5

plan precursors, and reevaluation of previously rejected control measures included in the initial Fairbanks 189(d) Plan, as well as identification of the MSMs adopted into any SIP or used in practice to control emissions in any state.

As part of its reevaluation of control measures, Alaska provided additional information for many of the control measures considered in the BACM analysis. The Fairbanks Revised 189(d) Plan includes additional consideration of banning installation of solid-fuel devices in new construction, limiting heating oil to ultra-low sulfur diesel, dry wood requirements, emissions controls for small area sources, mobile sources, and MSMs.

141

State Air Quality Control Plan, Vol. II, section III.D.7.7.12 (adopted November 5, 2024).

Alaska identified a burn-down period as part of other jurisdictions' solid fuel-fired heating device curtailment program. Accordingly, Alaska adopted a burn down period of three hours for solid-fuel heating devices that begins upon the effective date and time of a curtailment announcement. In addition, Alaska added specific requirements to document economic hardship as part of a NOASH curtailment program waiver for solid-fuel devices.

Regarding the requirement to demonstrate five percent annual reductions, Alaska included in the Fairbanks Revised 189(d) Plan a control strategy analysis that demonstrates annual reductions of PM

2.5

are greater than five percent through 2027, Alaska's projected attainment year.

142

Alaska noted that the State can demonstrate either five percent annual reductions in emissions of direct PM

2.5

or a five percent annual reductions in emissions of a PM

2.5

plan precursor. Alaska elected to demonstrate five percent annual reductions in direct PM

2.5

emissions. Thus, the EPA is proposing to approve the control strategy included in the Fairbanks Revised 189(d) Plan as meeting the requirements of CAA section 189(d) and 40 CFR 51.1010(c).

142

State Air Quality Control Plan, Vol. II, section III.D.7.9.2.3, Table 7.9-9.

D. Attainment Demonstration and Modeling

1. Statutory and Regulatory Requirements Regarding the Attainment Demonstration and Modeling

Pursuant to CAA sections 188(c) and 189(b) and 40 CFR 51.1003(b) and 51.1011(b), for nonattainment areas reclassified as Serious, the state must submit an attainment demonstration as part of the Serious Plan that meets the requirements of 40 CFR 51.1011. Similarly, pursuant to 40 CFR 51.1003(c), for Serious areas subject to CAA section 189(d) for failing to attain by the Serious area attainment date, the state must submit an attainment demonstration as part of the 189(d) plan that meets the requirements of 40 CFR 51.1011. On September 2, 2020, the EPA determined that the Fairbanks PM

2.5

Nonattainment Area failed to attain the 2006 24-hour PM

2.5

NAAQS by the December 31, 2019, Serious area attainment date. Therefore, the EPA is proposing to evaluate any previously unmet Serious area planning obligations based on the current, applicable attainment date appropriate under CAA section 189(d) and not the original Serious area attainment date.

143

In accordance with CAA section 172(a)(2)(A) and 40 CFR 51.1004(a)(3), the projected attainment date for Serious nonattainment areas subject to CAA section 189(d) shall be as expeditious as practicable, but no later than five years following the effective date of the EPA's finding that the area failed to attain by the original Serious area attainment date, except that the Administrator may extend the attainment date to the extent the Administrator deems appropriate, for a period no greater than 10 years from the effective date of the EPA's determination that the area failed to attain, considering the severity of nonattainment and the availability and feasibility of pollution control measures. In accordance with 40 CFR 51.1011, the attainment demonstration must meet four requirements:

143

The term “applicable attainment date” is defined at 40 CFR 51.1000 to mean: “the latest statutory date by which an area is required to attain a particular PM

2.5

NAAQS, unless EPA has approved an attainment plan for the area to attain such NAAQS, in which case the applicable attainment date is the date approved under such attainment plan. If EPA grants an extension of an approved attainment date, then the applicable attainment date for the area shall be the extended date.”

a. Identify the projected attainment date for the Serious nonattainment area that is as expeditious as practicable;

b. Meet the requirements of 40 CFR part 51, appendix W and include inventory data, modeling results, and emissions reduction analyses on which the state has based its projected attainment date;

c. The base year for the emissions inventories shall be one of the 3 years used for designations or another technically appropriate inventory year if justified by the state in the plan submission; and

d. The control strategies modeled as part of a Serious area attainment demonstration shall be consistent with the control strategies required pursuant to 40 CFR 51.1003 and 51.1010 (including the specific requirements in 40 CFR 51.1010(c)) for Serious areas that fail to attain.

Further, in accordance with 40 CFR 51.1011(b)(5), the attainment plan must provide for implementation of all control measures needed for attainment as expeditiously as practicable. Additionally, all control measures must be implemented no later than the beginning of the year containing the applicable attainment date, notwithstanding the BACM implementation deadline requirements in 40 CFR 51.1010.

144

40 CFR 51.1011(b)(5).

2. Summary of the EPA's Prior Rulemaking Regarding Attainment Demonstration and Modeling

The EPA disapproved Alaska's attainment demonstration in the initial Fairbanks 189(d) Plan because it did not fully meet CAA requirements.

145

As part of the attainment demonstration, the state must identify the projected attainment date that is as expeditious as practicable. Alaska did not adopt and implement all available control measures. The correct identification of the most expeditious attainment date requires an evaluation based upon expeditious implementation of the required emissions controls. Therefore, the EPA could not assess whether Alaska identified the expeditious attainment date for modeling purposes.

145

88 FR 84626, December 5, 2023, at p. 84676.

3. Summary of the State's Submission Regarding Attainment Demonstration and Modeling

The State included an updated attainment demonstration in the Fairbanks Revised 189(d) Plan.

146

In the plan, Alaska asserted that calendar year 2027 reflects attainment “as expeditiously as practicable,” based on air quality improvements from the base year to attainment year, as measured by the quantified emissions reductions

associated with the implementation of control measures.

147

146

State Air Quality Plan, Vol. II, section III.D.7.9 (adopted November 5, 2024).

147

State Air Quality Plan, Vol. II, section III.D.7.9.

Alaska noted that for attainment modeling, five-year design values are generally recommended. For the earlier Fairbanks Serious Plan, the base year modeling design value was 131.6 μg/m

. However, the latest five-year (2017-2021) design value is 64.9 μg/m

at the North Pole air quality monitor (Hurst Road), the area of expected highest PM

2.5

concentrations in the Fairbanks PM

2.5

Nonattainment Area. As part of updating its attainment analysis, Alaska identified this five-year design value of 64.9 μg/m

as the base year modeling design value for the Fairbanks Revised 189(d) Plan.

Building on the 2020 base year emissions inventory, Alaska developed a series of future year emissions inventories for each calendar year from 2020 through 2029. Alaska noted that each of these future year inventories accounted for growth in source activity over time (

e.g.,

increases in residential heating emissions resulting from forecasted housing growth). The emissions inventory also accounted for emissions reductions associated with both on-going state and local control programs (such as the Wood Stove Change Out and Solid Fuel-Burning Appliance Curtailment programs), along with other control measures included in the SIP that were adopted since the area was classified as a Serious area.

Alaska stated that source activity growth rates used to project the 2020 base year inventory emissions in calendar years 2021 through 2029 were generally based on the 2020-2024 and 2024-2035 annualized growth rates by source sector included in the Fairbanks Revised 189(d) Plan.

148

However, Alaska noted that the source activity growth rate for space heating was capped after model year 2027, and claimed this is due to the difficulty in reliably forecasting long-term energy prices and the likely peak in energy costs in 2024. Alaska also stated that the effects of the Federal mobile source and fuel control programs in projecting mobile source emissions from 2021 through 2029 were accounted for using the EPA's MOVES3 vehicle emissions model.

148

State Air Quality Plan, Vol. II, section III.D.7.6, Table 7.6-10.

Alaska included a list of the state and local control measures for which emissions benefits were quantified and included in the attainment date analysis.

149

Further, Alaska included a phase-in forecast for each control measure for 2020-2027 inventory years. See Table 4 of this preamble for a summary of these control measures:

149

State Air Quality Plan, Vol. II, section III.D.7.9, Table 7.9-1.

Table 4—Alaska Control Measures and Phase-In Schedule

Control measure

Percent compliance

2020

Base

year

2027

Attainment year

2027 Projected emissions

(tons per episodic day)

2.5

Details

Fairbanks Wood Stove Change Out Program

2,791

5,628

1.09

0.11

Based on funding from the 2016, 2017, 2018, 2019-2020, 2021, and 2022 Targeted Airshed Grants.

Solid Fuel-Burning Appliance Curtailment Program

30%

38%

Stage 1: 0.02; Stage 2: 0.12

Stage 1:—0.000; Stage 2:—0.02

In winter 2022-2023, Alaska conducted an observational field study from which compliance was estimated to be 38.1%.

Shift to diesel no. 1 fuel oil

n/a

50%

0.02

1.73

This measure required a one-time shift from the current mix of diesel no. 2 and diesel no. 1 heating oil refined and sold in the nonattainment area by September 2022.

Requires commercially sold wood to be dry before sale

n/a

50%

0.06

Less than 0.01

Requires commercially sold wood after October 1, 2021, to be dry, or if sold as 8-ft length rounds, requires proof of proper/adequate storage for drying by the buyer.

Removal of all uncertified devices & cordwood outdoor hydronic heaters

30%

0.25

−0.01

2024 is first year of implementation. Compliance rate estimates based on existing and on-going public education and outreach efforts.

2.0 g/hr and 0.10 lb/MMBtu certified emission rates for new or re-conveyed wood devices

22%

35%

0.09

Less than 0.01

The compliance rate estimated for this measure reflect the volume of home sales (projected from historical data) coupled with the requirement to register wood-fired heating devices upon sale or conveyance of a property.

Removal of coal heaters

n/a

25%

Less than 0.01

Wood-fired devices may not be primary or only heating source

20% (existing homes); 40% (new homes)

0.09

Less than 0.01

Beginning in 2024, compliance rates of 20% for new home sales (discounted for large lot, 2-acre cabin exemption) and 40% for home resales. The new home sale compliance rate is discounted from 40% to 20% to account for the estimated portion of large lot (greater than 2 acre) cabins which are exempted from this requirement.

NOASH/Exemption requirements

50%

Less than 0.01

Compliance rates reflect projected penetration rate increases associated with annual renewal and device registration requirements, proper installation and maintenance determinations from third-party verifiers, and requirements for catalyst replacement when manufacturer-recommended catalyst useful life is reached (estimated at six years averaged across manufacturers). These elements are also coupled with projected impacts from the NOASH reduction program funded under currently secured TAGs.

Alaska noted that, based on these phase-in forecasts, a detailed spreadsheet was developed to calculate PM

2.5

and SO

emissions reductions within the space heating sector for each measure in each inventory year.

150

The source activity data includes device and fuel splits, emission factors, and methods used to calculate control measure emissions benefits to support the control inventories developed for the attainment date analysis. Alaska further stated that the control measure emissions benefits calculations also account for the effects of overlap between measures that impact the same source category, properly eliminating double counting.

150

See

State Air Quality Plan, Vol. III, Appendix III.D.7.9.

Alaska stated that projected emissions control inventories for each year from 2020 through 2029 were prepared to support the analysis of expeditious attainment. Full modeling runs were completed for 2029, 2027, and 2026 in that order. After the 2029 modeling results demonstrated attainment of the PM

2.5

NAAQS, 2027 was selected as the next year to evaluate expeditious attainment.

To begin analyzing the 2027 attainment year, Alaska noted that the 2027 episodic modeling inventory was incorporated into the CMAQ air quality model. Modeled concentration outputs for this 2027 control inventory run were post-processed for each grid cell corresponding to ambient air quality monitors for which design values could be computed and processed through Alaska's Speciated Modeled Attainment Test (SMAT) tool (see State Air Quality Control Plan, Vol. II, section III.D.7.8.9). Alaska stated that the modeled design value at the controlling North Pole (Hurst Road) air quality monitor was found to be 31.9 μg/m

, below the 35 μg/m

NAAQS for 24-hour PM

2.5

and thus demonstrating modeled attainment by 2027.

To evaluate whether attainment could be advanced any sooner than 2027, Alaska compiled another emissions inventory for the 2026 model year. The 2026 CMAQ gridded outputs were then post-processed for the key monitor-based grid cells through the SMAT tool to develop modeled design values that reflected penetration of the State's control strategy package in 2026. Alaska stated that the 2026 modeled design value at the North Pole (Hurst Road) monitor was found to be 38.1 μg/m

, which exceeds the 35 μg/m

NAAQS.

As shown in Table 5 of this preamble, modeled design values in 2027 at all three regulatory air quality monitor locations in the Fairbanks PM

2.5

Nonattainment Area are below the 35 μg/m

24-hour PM

2.5

NAAQS. Alaska noted that the modeled design value at the controlling North Pole (Hurst Road) monitor is 31.9 μg/m

, more than 3 μg/m

below the NAAQS, which provides a “buffer” to account for concentrations in unmonitored grid cells across the nonattainment area. Modeled 2027 design values at the other two monitors near downtown Fairbanks are well below the PM

2.5

NAAQS.

Table 5—Fairbanks Modeled Attainment Summary

Fairbanks PM

2.5

air quality

monitor

Base year 2020

5-year PM

2.5

modeling design value (µg/m

2017-2021

Future 5-year

2.5

modeling design value

(µg/m

), 2026

Future 5-year

2.5

modeling design value

(µg/m

), 2027

North Pole (Hurst Road)

64.9

38.1

31.9

NCORE

27.7

19.8

18.4

A Street

34.8

24.5

22.7

Source:

State Air Quality Plan, Vol. II, section III.D.7.9, Table 7.9-12.

Alaska noted that even if emission controls were applied for precursor pollutants within applicable source sectors for which precursor significance determinations have been made (

i.e.,

emissions from major stationary sources in the Fairbanks PM

2.5

Nonattainment Area), the reduction in secondary PM

2.5

from such controls would not be sufficient to advance attainment sooner than 2027.

151

State Air Quality Control Plan, Vol. II, section III.D.7.9.3

Therefore, Alaska asserted that this evaluation demonstrates that 2027 is the most expeditious attainment date based on currently available data and demonstrate attainment “as expeditiously as practicable.”

4. The EPA's Evaluation and Proposed Action Regarding the Attainment Demonstration and Modeling

The EPA proposes to approve Alaska's attainment demonstration as meeting the requirements under 40 CFR 51.1011(b). Alaska demonstrated that the 2027 projected attainment date for the Serious nonattainment area is as expeditious as practicable. The attainment demonstration meets the requirements of Appendix W and includes inventory data, modeling results, and emissions reduction analyses on which the state has based its projected attainment date. As discussed in section II.A of this preamble, the base year for the emissions inventories for Alaska was 2020, which the EPA is proposing to determine is the technically appropriate inventory year. The EPA is proposing to determine that the control strategies in Alaska's SIP as rectified by the Fairbanks Revised 189(d) Plan satisfy the requirements of 40 CFR 51.1010. Therefore, the control strategies modeled as part of the attainment demonstration are consistent with the control strategies required pursuant to 40 CFR 51.1003 and 51.1010. With respect to the required timeframe for obtaining emissions reductions, all control measures needed for attainment will be implemented as expeditiously as practicable and implemented to attain the PM

2.5

NAAQS by 2027.

Pursuant to CAA section 172(a)(2)(A) and 40 CFR 51.1004(a)(3), the EPA is proposing to extend the attainment date for the Fairbanks PM

2.5

Nonattainment Area to December 31, 2027. As shown in Table 5 of this preamble, the 2020 base year design value at the Hurst Road monitoring station is 64.9 µg/m

. This design value is well above the PM

2.5

24-hour NAAQS of 35 µg/m

, indicating the air quality problem in the Fairbanks PM

2.5

Nonattainment Area remains severe. However, Alaska has demonstrated that attainment earlier than 2027 is not feasible. Moreover, the EPA has reviewed Alaska's evaluations (and re-evaluations) of available control measures and proposes to determine that Alaska's control strategy meets the requirements of CAA section 189(b) and 189(d) and 40 CFR 51.1010. By extension, the EPA proposes to determine that there are no other feasible measures that Alaska could implement that would advance attainment to a date earlier than December 31, 2027.

As discussed in section II.E of this preamble regarding Reasonable Further Progress, the primary drivers of emissions reductions will be continued implementation of the wood stove change out program, the Solid Fuel-Burning Appliance Curtailment Program, and the switch from diesel no. 2 fuel oil to diesel no. 1 fuel oil. The rate of wood stove change-outs in a single season is constrained based on the availability of certified installers and residential demand. Similarly, higher sulfur fuel cannot feasibly be eliminated from the Fairbanks PM

2.5

Nonattainment Area until 2026

152

due to the time necessary to expend all residual diesel no. 2 fuel oil and for diesel no. 1 to fully flush out any remaining higher sulfur residue. Finally, Alaska conducted a recent assessment of compliance with the Solid Fuel-Burning Appliance Curtailment Program that indicated a compliance rate of 38 percent.

153

Given the variability of compliance with this program in past, Alaska does not project a near-term improvement in the compliance rate. Therefore, the EPA has considered the severity of nonattainment and the availability and feasibility of control measures as required under CAA section 172(a)(2)(A) and 40 CFR 51.1004(a)(3).

152

State Air Quality Control Plan, Vol. II, section III.D.7.10, Table 7.10-4.

153

State Air Quality Control Plan, Vol. III, Appendix III.D.7.9, at p. Appendix III.D.7.14-12.

E. Reasonable Further Progress

1. Statutory and Regulatory Requirements Regarding Reasonable Further Progress

Pursuant to CAA section 172(c) and 40 CFR 51.1012, each attainment plan for a PM

2.5

nonattainment area shall include Reasonable Further Progress (RFP) provisions that demonstrate that control measures in the area will achieve such annual incremental reductions in emissions of direct PM

2.5

and PM

2.5

plan precursors as are necessary to ensure attainment of the applicable PM

2.5

NAAQS as expeditiously as practicable. As discussed in section I of this preamble, on September 2, 2020, the EPA determined that the Fairbanks PM

2.5

Nonattainment Area failed to attain the 2006 24-hour PM

2.5

NAAQS by the applicable December 31, 2019, Serious area attainment date. Therefore, the EPA is proposing to evaluate any previously unmet Serious area planning obligations, including RFP and quantitative milestone requirements, based on the current, applicable attainment date appropriate under CAA section 189(d) and not the original Serious area attainment date. In accordance with 40 CFR 51.1012, the RFP plan shall include all of the following:

a. A schedule describing the implementation of control measures during each year of the applicable attainment plan. Control measures for Moderate area attainment plans are required in 40 CFR 51.1009, and control

measures for Serious area attainment plans are required in 40 CFR 51.1010.

b. RFP projected emissions for direct PM

2.5

and all PM

2.5

plan precursors for each applicable milestone year, based on the anticipated implementation schedule for control measures required by 40 CFR 51.1009 and 51.1010. For purposes of establishing motor vehicle emissions budgets for transportation conformity purposes (as required in 40 CFR part 93, subpart A) for a PM

2.5

nonattainment area, the state shall include in its RFP submission an inventory of on-road mobile source emissions in the nonattainment area for each milestone year.

154

For an evaluation of motor vehicle emission budgets, see section II.H of this preamble.

c. An analysis that presents the schedule of control measures and estimated emissions changes to be achieved by each milestone year, and that demonstrates that the control strategy will achieve reasonable progress toward attainment between the applicable base year and the attainment year. The analysis shall rely on information from the base year inventory for the nonattainment area required in 40 CFR 51.1008(a)(1) and the attainment projected inventory for the nonattainment area required in 40 CFR 51.1008(a)(2), in addition to the RFP projected emissions required in 40 CFR 51.1012(a)(2).

d. An analysis that demonstrates that by the end of the calendar year for each milestone date for the area determined in accordance with 40 CFR 51.1013(a), pollutant emissions will be at levels that reflect either generally linear progress or stepwise progress in reducing emissions on an annual basis between the base year and the attainment year. A demonstration of stepwise progress must be accompanied by appropriate justification for the selected implementation schedule.

2. Summary of the EPA's Prior Rulemaking Regarding Reasonable Further Progress

The EPA disapproved the RFP provisions in the Fairbanks Serious Plan and Fairbanks 189(d) Plan because the control strategies in those prior plans did not include all required control measures.

155

This caused uncertainty as to whether the RFP provisions of those plans accurately projected progress towards the most expeditious attainment year, per CAA section 172(c)(2) and 40 CFR 51.1012.

155

88 FR 84626, December 5, 2023, at p. 84676.

3. Summary of the State's Submission Regarding Reasonable Further Progress

The Fairbanks Revised 189(d) Plan includes updated RFP provisions at State Air Quality Control Plan, Vol. II, section III.D.7.10.

156

Consistent with the attainment demonstration provisions discussed in the preceding paragraphs, these updated RFP provisions reflect the attainment year of 2027.

157

The updated RFP analysis includes a schedule that includes 2020 as the base year, 2027 as the attainment year, and the following years as RFP and quantitative milestone analysis years: 2023, 2026, and 2029.

158

156

Adopted November 5, 2024.

157

RFP provisions in prior SIP submissions for the Fairbanks PM

2.5

Nonattainment Area reflected varying projected attainment dates. Initially Alaska submitted an RFP plan in the Fairbanks Serious Plan based on the projected attainment year of 2029. Alaska withdrew and replaced the RFP plan in the Fairbanks 189(d) plan based on the revised 2024 attainment projection.

158

See

State Air Quality Plan, Vol. II, section III.D.7.10.2.

Alaska included an analysis of implementation of all control measures that establishes the scheduled phase-in of each measure adopted and estimation of emissions reductions for each significant pollutant (also accounting for the overlapping of measures to eliminate double counting) for each milestone year based on the phase-in schedule. Alaska calculated the RFP and quantitative milestone (QM) milestone year emissions reduction targets based on linear progress towards attainment by 2027. Based on the control measure phase-in schedule, Alaska calculated projected emissions reductions for each pollutant in each milestone year and compared these emissions reductions to their targets to evaluate linear progress toward attainment.

Alaska has continued to assess the appropriate compliance rate estimate. As Alaska noted in the Fairbanks Revised 189(d) Plan, the State is currently utilizing funding from the 2019-2020 TAG to purchase three dynamic message highway signs and an infrared camera and to expand staffing to increase compliance.

159

Alaska continues to conduct field studies during the wintertime to observe compliance rates. Based on the recent 2022-2023 wintertime field study, Alaska determined that the combined compliance rate in Fairbanks and the North Pole is 38.1 percent. Based on these observations and the increased use of TAG funding to improve compliance, Alaska increased its compliance estimate with the curtailment program to 38 percent for the 2023 model year, an increase from 30 percent in 2020. Alaska plans to conduct additional wintertime curtailment program compliance observations to inform anticipated improvements in compliance beyond 2023. For the attainment year projected emissions inventory, Alaska stated that it conservatively assumed no further compliance rate increases pending further evaluation of additional wintertime compliance observations.

160

159

State Air Quality Plan, Vol. II, section III.D.7.9.1.1.

160

Id.

Alaska stated that direct PM

2.5

emissions reductions achieved within the first two milestone years (2023 and 2026) achieve stepwise progress.

161

However, reductions in direct PM

2.5

emissions in the attainment year of 2027 reflect linear progress. According to Alaska's submission, this is attributable to a spike in participation in the wood stove change out program anticipated by 2027 (based on increased incentives and deadlines for older device turnover) and gradual improvements in household compliance with control strategies impacting solid fuel-burning devices.

161

State Air Quality Plan, Vol. II, section III.D.7.10.3.3.

With respect to SO

, Alaska stated that SO

emissions reductions are expected to be non-linear but includes early year (2023 and 2026) progress that significantly exceeds the linear progress trajectory.

162

Alaska stated that this non-linearity in control measure reductions for SO

is due to two causes. First, most of the measures designed to reduce direct PM

2.5

through removal, curtailment, or replacement of solid-fuel devices trigger a shift from space heating devices that emit high levels of direct PM

2.5

to oil-fired devices that emit very low levels of direct PM

2.5

(but can lead to higher levels of SO

emissions depending on the fuel sulfur content). Second, initial reductions in SO

emissions are the result of Alaska implementing an SO

-specific control measure in 2022 mandating a shift from diesel no. 2 to diesel no. 1 heating oil. Thus, emissions reductions for SO

exhibit stepwise rather than linear progress.

162

Id.

Regarding NH

, Alaska stated that linearly established targets for NH

will not be met until the forecasted 2027 attainment year.

163

Alaska noted that the increases in NH

emissions are not due to control measure benefits or lack thereof. Although Alaska adopted and implemented control measures to reduce NH

, Alaska did not calculate any NH

emissions reductions for these measures for the purposes of RFP due to

the large uncertainty in NH

emissions factors for key sources.

163

Id.

4. The EPA's Evaluation and Proposed Action Regarding Reasonable Further Progress

The EPA is proposing to approve the Fairbanks Revised 189(d) Plan as meeting the RFP requirements in CAA section 172(c)(2) and 40 CFR 51.1012. The RFP provisions in the Fairbanks Revised 189(d) Plan meet each of the requirements in 40 CFR 51.1012(a)(1)-(4). First, the RFP provisions include a schedule describing the implementation of control measures during each year of the applicable attainment plan.

164

Second, the Fairbanks Revised 189(d) Plan includes RFP projected emissions for direct PM

2.5

and all PM

2.5

plan precursors for each applicable milestone year based on the phase-in schedule.

165

Third, the Fairbanks Revised 189(d) Plan includes an analysis that presents the schedule of control measures and estimated emissions changes to be achieved by each milestone year: 2023, 2026, and 2029.

166

This analysis relies on information from the base year inventory and attainment projected inventories in State Air Quality Control Plan, Vol. II, section III.D.7.8, as well as the RFP projected emissions. The analysis demonstrates that the control strategy will achieve reasonable progress toward attainment between the applicable base year and the attainment year.

167

164

Id.

at section III.D.7.10.3.2;

See also

State Air Quality Control Plan, Vol. III, Appendix III.D.7.10.

165

Id.

at section III.D.7.10.3.3, Table 7.10-5.

166

Id.

at section III.D.7.10.3.2, Table 7.10-4.

167

Id.

at section III.D.7.10.3, Tables 7.10-4-7.10-5; Figures 7.10-3-7.10-5. Note that NH

emissions are projected to increase from base year to the projected attainment year. As discussed in the preceding paragraphs regarding the control strategy, the EPA either has previously approved Alaska's control strategy as meet planning requirements for sources of NH

This is primarily because there are either no controls for sources of NH

emissions in the Fairbanks PM

2.5

Nonattainment Area or the direct PM

2.5

emissions controls are sufficient to control NH

emissions.

Finally, the Fairbanks Revised 189(d) Plan includes an analysis that demonstrates that by the end of the calendar year for each milestone date, pollutant emissions will be at levels that reflect either linear progress or stepwise progress in reducing emissions on an annual basis between the base year and attainment year. As discussed in section II.E.3 of this preamble, Alaska's projections for reductions in direct PM

2.5

reductions closely track linear progress. The EPA proposes to determine that the slight deviations from linear progress in the initial years of implementation are justified. The EPA recognizes the episodic nature of wood-stove change outs and the time lag between state enforcement and deterrence.

With respect to SO

emissions reductions, Alaska projects emissions well below linear progress in 2023 and 2026 milestone years. As discussed in section II.E.3 of this preamble, the early-year reductions are due to near-term implementation of the control strategy requirement to switch to lower sulfur fuels. These early reductions are consistent with the overall goal of achieving attainment as expeditiously as practicable.

168

The EPA proposes to determine that Alaska adequately justified the leveling off of SO

emissions reductions in 2027 as due to the near-term implementation of the fuel switch as well as the increase in SO

emissions from residents switching from solid fuel-fired heating devices to liquid fuel-fired heating devices to comply with other measures in the control strategy targeting sources of direct PM

2.5

168

See

CAA section 189, 42 U.S.C. 7513a, Addendum to the General Preamble, 59 FR 41998 (August 16, 1994), at p. 42016.

Finally, with respect to NH

, the EPA proposes to determine that Alaska adequately justified the increase in emissions. The EPA has previously approved Alaska control strategy for NH

, noting that sources in the Fairbanks PM

2.5

Nonattainment Area emit a negligible amount of NH

and there are no specific controls for the types of sources in the area.

169

Therefore, the EPA is proposing to approve the Fairbanks Revised 189(d) Plan as meeting the RFP requirements in CAA section 172(c)(2) and 40 CFR 51.1012.

169

88 FR 84626, December 5, 2023, at p. 84636

F. Quantitative Milestones

1. Statutory and Regulatory Requirements Regarding the Quantitative Milestones

In accordance with CAA section 189(c)(1) and 40 CFR 51.1013, the state must submit in each attainment plan for a PM

2.5

nonattainment area specific quantitative milestones that provide for objective evaluation of RFP toward timely attainment of the applicable PM

2.5

NAAQS in the area.

For an attainment plan submission for a Serious area subject to the requirements of CAA section 189(d) and 40 CFR 51.1003(c), each plan shall contain quantitative milestones that provide for objective evaluation of reasonable further progress toward timely attainment of the applicable PM

2.5

NAAQS in the area.

170

At a minimum, each plan for an area subject to CAA section 189(d) must include QMs for tracking progress achieved in implementing the SIP control measures by each milestone date.

171

170

40 CFR 51.1013(a)(3).

171

40 CFR 51.1013(a)(3)(ii).

In the preamble to the PM

2.5

SIP Requirements Rule, the EPA stated that it interprets the CAA as allowing states to identify milestones that are suitable for the specific facts and circumstances of the attainment area.

172

The EPA suggested possible metrics, including tracking air quality improvement, tracking emissions reductions, percentage implementation of control strategies, or percent compliance with implemented control measures.

173

Finally, the EPA stated in the preamble that quantitative milestones will be met by showing that emissions reductions scheduled to be made between the SIP due date and the attainment date were actually achieved.

174

172

Id.

173

81 FR 58010, Aug. 24, 2016, at pp. 58064, 58104.

174

Id.

Regarding the specific timeframe for the Fairbanks PM

2.5

Nonattainment Area, per 40 CFR 51.1013(a)(4), each attainment plan submission for an area designated nonattainment for the 1997 and/or 2006 PM

2.5

NAAQS before January 15, 2015, shall contain quantitative milestones to be achieved no later than 3 years after December 31, 2014, and every 3 years thereafter until the milestone date that falls within 3 years after the applicable attainment date.

2. Summary of the EPA's Prior Action Regarding the Quantitative Milestones

The EPA disapproved the quantitative milestones in the Fairbanks Serious Plan and Fairbanks 189(d) Plan because the control strategies in those prior plans did not include all required control measures.

175

This caused uncertainty as the whether the quantitative milestones were based on progress towards the most expeditious attainment year.

175

88 FR 84626, December 5, 2023, at p. 84676.

3. Summary of the State's Submission Regarding the Quantitative Milestones

Alaska submitted revised quantitative milestones in the Fairbanks Revised 189(d) Plan. As noted in section II.E of this preamble, Alaska's updated RFP analysis is based on a schedule that includes 2020 as the base year, 2027 as the attainment year, and the following years as quantitative milestone years:

2023, 2026, and 2029.

176

Alaska used emissions reductions achieved compared to projected emissions reductions as the metric to objectively evaluate progress toward attainment.

177

Alaska calculated expected emissions reductions based on the control measure phase-in schedule.

178

In its Quantitative Milestone Reports required by CAA section 189(c) and 40 CFR 51.1013(b), Alaska reported the emissions reductions achieved by the end of the milestone year compared to the projected emissions reductions included in the quantitative milestone provisions in the Fairbanks Revised 189(d) Plan, specifically, State Air Control Quality Plan, Vol. II, section III.D.7.10.3. Alaska made clear that the state will include in its QM reports completion statistics and phase-in percentages for each measure included in the Fairbanks Revised 189(d) Plan.

179

176

See

State Air Quality Control Plan, Vol. II, section III.D.7.10.2.

177

Id.

178

Id.

at section III.D.7.10.3.3, Table 7.10-5.

179

Id.

at section III.D.7.10.2.

According to the Fairbanks Revised 189(d) Plan, one of Alaska's reasons for selecting emissions reductions achieved compared to projected emissions reductions as the objective metric is because doing so allows Alaska to take credit for emissions reductions from voluntary measures that are not part of its control strategy.

180

Alaska provided the example of emissions reductions attributable to natural gas expansion. As discussed further below in section II.F.4 of this preamble, the EPA disagrees with this specific rationale for allowing the state to take credit for emissions reductions from voluntary measures that are not part of its control strategy.

180

Id.

4. The EPA's Evaluation and Proposed Action Regarding the Quantitative Milestones

The EPA is proposing to approve the Fairbanks Revised 189(d) Plan as meeting the quantitative milestone requirements of CAA section 189(c)(1) and 40 CFR 51.1013. First, in accordance with 40 CFR 51.1013(a)(3)(ii) and (4), the Fairbanks Revised 189(d) Plan includes quantitative milestones for the years 2023, 2026, and 2029. Second, the Fairbanks Revised 189(d) Plan includes phase-in metrics for each measure in the control strategy, including measures necessary to meet the BACM and BACT requirements in CAA section 189(b) and 40 CFR 51.1010(a) and the requirements of CAA section 189(d) and 40 CFR 51.1010(c).

Finally, the measures allow for objective evaluation of RFP. As stated in the preceding paragraphs, the EPA interprets the CAA as allowing states to identify milestones that are suitable for the specific facts and circumstances of the attainment area. The EPA proposes to determine that Alaska's quantitative milestones provide objective evaluation of RFP and are suitable for the specific facts and circumstances for the Fairbanks PM

2.5

Nonattainment Area. Although the EPA agrees that comparing emissions reductions achieved to projected emissions reductions allows for objective evaluation of RFP for the Fairbanks PM

2.5

Nonattainment Area, the EPA disagrees with Alaska's stated rationale for selecting this metric. The purpose of QMs is to provide an objective evaluation of the state's implementation of the SIP control measures.

181

Therefore, crediting emissions reductions attributable to non-SIP measures toward achieving a QM is inconsistent with CAA section 189(c) and 40 CFR 51.1013.

181

See

40 CFR 51.1013(a)(3)(ii) (“At a minimum, each quantitative milestone plan must include a milestone for tracking progress

achieved in implementing the SIP control measures

by each milestone date.”) (emphasis added).

Nevertheless, using emissions reductions as the metric is appropriate for the Fairbanks Revised 189(d) Plan because of the overlapping nature of control measures and associated emissions reductions, particularly those focused on the space heating area source sector. Specifically, the implementation of specific measures designed to reduce emissions from solid fuel-fired burning devices impacts nearly all other area-source controls measures. For example, the wood stove change out program removes wood stoves from the emissions inventory. This reduces direct PM

2.5

emissions, but also impacts the emissions reductions achieved by the Solid Fuel-Burning Appliance Curtailment Program and dry wood requirements.

Alaska could achieve more wood stove change-outs than it projects in a milestone year and, thus, achieve more emissions reductions attributable to that measure. However, that measure, by its nature, changes the makeup of the remaining wood stove users and their collective compliance with dry wood requirements and the curtailment program. Thus, there could be an instance where Alaska overperforms on one wood stove control measure, and that overperformance causes an underperformance on one or more other similar measures, but that collectively the measures achieve RFP.

Relatedly, the wood stove change out program has the potential to moderate the benefits of measures designed to reduce SO

emissions by increasing the number of residences using oil fuel-fired heating devices. Comparing emissions reductions achieved to projected emissions reductions as the milestone metric allows Alaska to take into consideration these complex interactions and ultimately provides a more meaningful assessment of whether Alaska's plan is achieving RFP.

In addition to the emissions reduction metric, the Fairbanks Revised 189(d) Plan includes several other objective metrics for RFP, including the number of wood stoves changed out, compliance percentage for tracking the progress of the solid-fuel burning device change out program, and percent implementation as metrics for the fuel sulfur content shift mandate, dry wood requirements, mandatory wood device removal, and more stringent no other adequate source of heat requirements.

Alaska has demonstrated its ability to include emissions reduction statistics in its quantitative milestone reports. On March 29, 2024, Alaska submitted its quantitative milestone report for quantitative milestone year 2023 (“2023 QM Report”). The EPA determined the 2023 QM Report

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