Air Plan Approval; ID: Logan Utah-Idaho PM2.5

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule.

SUMMARY:

The Environmental Protection Agency (EPA) is proposing to redesignate the Idaho portion of the Logan, Utah-Idaho fine particulate matter (PM_2.5) nonattainment area (Logan UT-ID NAA) to attainment for the 2006 PM_2.5 National Ambient Air Quality Standard (NAAQS). EPA is also proposing to approve a maintenance plan for the area demonstrating continued compliance with the 2006 PM_2.5 NAAQS through 2031, which the Idaho Department of Environmental Quality (IDEQ) submitted along with the redesignation request on September 13, 2019, for inclusion into the Idaho State Implementation Plan (SIP). Additionally, EPA is proposing to approve the 2031 motor vehicle emissions budgets included in Idaho's maintenance plan for PM_2.5, nitrogen oxides (NO_X) and volatile organic compounds (VOC). EPA is proposing this action pursuant to the Clean Air Act (CAA or the Act).

DATES:

Comments must be received on or before March 19, 2021.

ADDRESSES:

Submit your comments, identified by Docket ID No. EPA-R10-OAR-2020-0190, at https://www.regulations.gov. Follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from Regulations.gov. EPA may publish any comment received to its public docket. Do not electronically submit 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. 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:

Adam Clark, (206) 553-1495, clark.adam@epa.gov.

SUPPLEMENTARY INFORMATION:

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

Table of Contents

I. Background

II. Requirements for Redesignation to Attainment

III. EPA's Analysis of Idaho's Submittal

A. Attainment Determination

B. Applicable Requirements Under Section 110 and Part D of the CAA

1. CAA Section 110 General SIP Requirements

2. Part D of Title I Requirements

3. Fully Approved SIP Under CAA Section 110(k)

C. Improvement in Air Quality Due to Permanent and Enforceable Measures

D. Fully Approved Maintenance Plan

1. Attainment Inventory

2. Maintenance Demonstration

3. Monitoring Network

4. Verification of Continued Attainment

5. Contingency Plan

E. Requirements for Transportation Conformity and Motor Vehicle Emissions Budgets (MVEBs)

IV. Proposed Action

V. Statutory and Executive Order Reviews

I. Background

On October 17, 2006 (71 FR 61144), EPA revised the level of the 24-hour PM_2.5 NAAQS, lowering the primary and secondary standards from the 1997 standard of 65 micrograms per cubic meter (µg/m³) to 35 µg/m³. On November 13, 2009, EPA designated a portion of Franklin County, Idaho in addition to portions of Cache County, Utah nonattainment for the 2006 24-hour PM_2.5 NAAQS (74 FR 58688). This cross-boundary nonattainment area is referred to as the Logan, UT-ID PM_2.5 NAA.

The boundaries of the Logan, UT-ID PM_2.5 NAA roughly conform to the geographic boundaries of the Cache Valley. The Cache Valley is an isolated, bowl-shaped valley measuring approximately 60 kilometers north to south and 20 kilometers east to west and almost entirely surrounded by mountain ranges. The Wellsville Mountains lie to the west, and on the east lie the Bear River Mountains; both are northern branches of the Wasatch Range. This topography can act as a barrier to air movement in the Cache Valley during temperature inversions, which occur in the winter months and are often the cause of elevated concentrations of fine particulates. Additional information pertaining to the unique issues associated with the Logan, UT-ID PM_2.5 NAA and studies completed on inversions can be found in the docket for Utah and Idaho in the November 13, 2009, final designations action for the 2006 24-Hour PM_2.5 NAAQS (74 FR 58688).

The nonattainment designation of the Logan UT-ID PM_2.5 NAA required Idaho to prepare and submit an attainment plan to meet statutory and regulatory requirements in the Idaho portion of the Logan, UT-ID PM_2.5 NAA. IDEQ submitted this attainment plan to EPA on December 14, 2012, and supplemented the attainment plan on December 24, 2014. The attainment plan addressed specific required elements, including but not limited to the following elements: Emissions inventory, Reasonably Available Control Measures/Technology (RACM/RACT), attainment demonstration, contingency measures, and Motor Vehicle Emissions Budgets (MVEBs). EPA approved the baseline emissions inventory on July 18, 2014 (79 FR 41904) and the control measures on March 25, 2014 (79 FR 16201). EPA approved the control measures in the attainment plan as meeting RACM/RACT and disapproved contingency measures on January 4, 2017 (82 FR 729). EPA approved the attainment demonstration on August 8, 2017 (82 FR 37025). We also approved a separate, March 20, 2018, Idaho SIP revision as meeting applicable part D nonattainment new source review (NSR) requirements on August 20, 2018 (83 FR 42033). Most recently, we approved the attainment plan as meeting the Reasonable Further Progress (RFP), Quantitative Milestone (QM), and MVEB requirements on February 20, 2020 (85 FR 9664).

On September 8, 2017 (82 FR 42447), EPA granted two, one-year extensions, under CAA section 188(d), to the December 31, 2015 Moderate attainment date for the 2006 24-hour PM_2.5 Logan, UT-ID NAA. On October 19, 2018, EPA finalized a determination that the Logan, UT-ID PM_2.5 NAA had attained the 2006 primary and secondary 24-hour PM_2.5 NAAQS (“Determination of Attainment”) by the December 31, 2017, attainment date (83 FR 52983). Additionally, EPA finalized a determination that the obligation to submit any remaining attainment-related SIP revisions arising from classification of the Logan, UT-ID NAA as Moderate under subpart 4 of part D (of title I of the Act) for the 2006 24-hour PM_2.5 NAAQS are not applicable for so long as the area continues to attain the 2006 24-hour PM_2.5 NAAQS. See 40 CFR 51.1015(a) (known as a “Clean Data Determination” or “CDD”).

II. Requirements for Redesignation to Attainment

The CAA provides the requirements for redesignating a nonattainment area to attainment. Specifically, section 107(d)(3)(E) of the CAA, 42 U.S.C. 7407(d)(3)(E), allows for redesignation provided that: (1) EPA determines that the area has attained the applicable NAAQS; (2) EPA has fully approved the applicable implementation plan for the area under section 110(k) of the CAA; (3) EPA determines that the improvement in air quality is due to permanent and enforceable reductions in emissions resulting from implementation of the applicable SIP and applicable federal air pollutant control regulations and other permanent and enforceable reductions; (4) EPA has fully approved a maintenance plan for the area as meeting the requirements of section 175A of the CAA; and (5) the state containing such area has met all requirements applicable to the area under section 110 and part D of the CAA. In this proposed action, EPA will review CAA section 107(d)(3)(E) requirements (2) and (5) together as part of our evaluation of Idaho's redesignation request.

EPA has provided guidance on redesignation in the “General Preamble,” and has provided further guidance on processing redesignation requests in the following documents: (1) “Procedures for Processing Requests to Redesignate Areas to Attainment,” Memorandum from John Calcagni, Director, Air Quality Management Division, September 4, 1992 (hereafter the “Calcagni Memo”); (2) “State Implementation Plan (SIP) Actions Submitted in Response to Clean Air Act (CAA) Deadlines,” Memorandum from John Calcagni, Director, Air Quality Management Division, October 28, 1992; and (3) “Part D New Source Review (Part D NSR) Requirements for Areas Requesting Redesignation to Attainment,” Memorandum from Mary D. Nichols, Assistant Administrator for Air and Radiation, October 14, 1994. These documents are included in the Docket for this proposed action.

III. EPA's Analysis of Idaho's Submittal

EPA is proposing to redesignate the Franklin County, ID portion of the Logan UT-ID NAA to attainment for the 2006 24-hour PM_2.5 NAAQS and proposing to approve into the Idaho SIP the associated maintenance plan. EPA's proposed approval of the redesignation request and maintenance plan is based upon EPA's determination that the area continues to attain the 2006 24-hour PM_2.5 NAAQS and that all other redesignation criteria have been met for the area. The following is a description of how Idaho's September 13, 2019, submittal satisfies the requirements of section 107(d)(3)(E) of the CAA for the 2006 24-hour PM_2.5 standard.

A. Attainment Determination

To redesignate an area from nonattainment to attainment, the CAA requires EPA to determine that the area has attained the applicable NAAQS (CAA section 107(d)(3)(E)(i)). Whether an area has attained the 2006 24-hour PM_2.5 NAAQS is based upon measured air quality levels at each eligible monitoring site with a complete three-year period to produce a design value equal to or below 35 µg/m³. See 40 CFR part 50 and 40 CFR part 50, appendix N. A state must demonstrate that an area has attained the 2006 24-hour PM_2.5 NAAQS through submittal of ambient air quality data from an ambient air monitoring network representing maximum PM_2.5 concentrations. The data must be quality assured, quality-controlled and certified in the EPA's Air Quality System (AQS) and it must show that the three-year average of valid PM_2.5 98th percentile mass concentrations is equal to or below the 2006 24-hour PM_2.5 NAAQS (35 µg/m³), pursuant to 40 CFR 50.13. In making this showing, three consecutive years of complete air quality data must be used.

As noted, on October 19, 2018, EPA finalized a Determination of Attainment for the Logan, UT-ID PM_2.5 NAA based upon quality-assured and certified ambient air quality monitoring data for the period of 2015-2017 (83 FR 52983). The monitoring data used as the basis for the Determination of Attainment under CAA section 188(b)(2) is provided in Table 1 of this document.

EPA has also reviewed the subsequent PM_2.5 ambient air monitoring data in the Logan UT-ID area for the monitoring design value periods of 2016-2018 and 2017-2019. Consistent with the requirements at 40 CFR part 50, Idaho quality assured, quality-controlled and certified this ambient air monitoring data in the EPA's Air Quality System (AQS). This air quality data demonstrates that the Logan UT-ID area continues to attain the 2006 24-hour PM_2.5 NAAQS. For the 2016-2018 three-year period, the Smithfield monitor recorded a design value of 33 µg/m. The area's 24-hour PM_2.5 design values for the 2017-2019 three-year period are provided in Table 2 of this document.

As Table 2 indicates, the Logan UT-ID PM_2.5 NAA has continued to attain the 2006 24-hour PM_2.5 NAAQS since EPA issued its October 19, 2018, Determination of Attainment for the area based on the 2015-2017 design values shown in Table 1 of this document. We note that the Preston, ID monitor did not produce a valid design value for the 2017-2019 period because the monitor did not begin operation until February 24, 2017, thus producing an incomplete first quarter for that monitoring year. Despite this, EPA finds that it is appropriate to conclude that the area has continued to attain the NAAQS since the initial 2015-2017 period upon which we based our October 19, 2018, Determination of Attainment, based on uninterrupted attainment at the Smithfield, UT monitor. A review of concurrent monitoring data for the Smithfield and Preston monitors provided in Table 2 of this document, and discussed in more detail in our Technical Support Document (TSD) included in the docket for this proposed action, shows that the Smithfield site typically records higher levels of PM_2.5 than the Preston site, indicating that Smithfield's location is more suitable to demonstrate maximum PM_2.5 concentrations in the Cache Valley. On September 1, 2020, Utah and Idaho completed a memorandum of understanding (MOU) to collectively meet the monitoring requirements of 40 CFR part 58, Appendix D in the Logan UT-ID metropolitan statistical area (MSA), allowing Idaho to rely on the Smithfield monitor in Utah as the highest concentration monitor in the MSA. As shown, the Smithfield monitor has attained the 2006 24-hour PM_2.5 NAAQS for the 2015-2017, 2016-2018 and 2017-2019 design value periods. The MOU is included in the docket for this proposed action. The TSD also demonstrates that it is very unlikely that the Preston monitor's first complete valid design value for the 2018-2020 period could exceed the 2006 PM_2.5 NAAQS based on a review of all available data recorded at this monitor.

EPA's review of the monitoring data for 2016-2018 and 2017-2019 supports the previous determination that the area has attained the 2006 24-hour PM_2.5 NAAQS and demonstrates that the area continues to attain the standard. As discussed further in Section III.D of this document, Idaho has committed to continue monitoring ambient PM_2.5 concentrations in accordance with 40 CFR part 58. Thus, EPA is proposing to determine that the Logan UT-ID PM_2.5 NAA attained the 2006 24-hour PM_2.5 NAAQS.

B. Applicable Requirements Under Section 110 and Part D of the CAA

Section 107(d)(3)(E)(ii) and (v) of the CAA states that for an area to be redesignated to attainment, it must be determined that the Administrator has fully approved the applicable implementation plan for the area under CAA section 110(k) and all the requirements applicable to the Area under section 110 of the CAA (general SIP requirements) and part D of Title I of the CAA (SIP requirements for nonattainment areas) must be met.

1. CAA Section 110 General SIP Requirements

Section 110(a)(2) of Title I of the CAA delineates the general requirements for a SIP, which include enforceable emissions limitations and other control measures, means or techniques, provisions for the establishment and operation of appropriate devices necessary to collect data on ambient air quality, and programs to enforce the limitations. The general SIP elements and requirements set forth in CAA section 110(a)(2) include, but are not limited to the following:

• Submittal of a SIP that has been adopted by the state after reasonable public notice and hearing;
• Provisions for establishment and operation of appropriate procedures needed to monitor ambient air quality;
• Implementation of a source permit program; provisions for the implementation of Part C requirements (PSD);
• Provisions for the implementation of Part D requirements for NSR permit programs;
• Provisions for air pollution modeling; and
• Provisions for public and local agency participation in planning and emission control rule development.

CAA section 110(a)(2)(D) requires that SIPs contain certain measures to prevent sources in a state from significantly contributing to air quality problems in another state. However, CAA section 110(a)(2)(D) requirements for a state are not linked with a particular nonattainment area's designation and classification in that state. EPA believes that the requirements linked with a particular nonattainment area's designation and classifications are the relevant measures to evaluate in reviewing a redesignation request. The transport SIP submittal requirements, where applicable, continue to apply to a state regardless of the designation of any one particular area in the state. Thus, EPA does not believe that these requirements are applicable requirements for purposes of redesignation.

In addition, EPA believes that the other CAA section 110(a)(2) elements not connected with nonattainment plan submissions and not linked with an area's attainment status are not applicable requirements for purposes of redesignation because the area will still be subject to these requirements after it is redesignated. EPA concludes that the CAA section 110(a)(2) and part D requirements which are linked with a particular area's designation and classification are the relevant measures to evaluate in reviewing a redesignation request, and that CAA section 110(a)(2) elements not linked to the area's nonattainment status are not applicable for purposes of redesignation. This approach is consistent with EPA's existing policy on applicability of conformity (i.e., for redesignations) and oxygenated fuels requirement. See Reading, Pennsylvania, proposed and final rulemakings (61 FR 53174, October 10, 1996), (62 FR 24826, May 7, 1997); Cleveland-Akron-Lorain, Ohio final rulemaking (61 FR 20458, May 7, 1996); and Tampa, Florida, final rulemaking (60 FR 62748, December 7, 1995). See also, the discussion on this issue in the Cincinnati, Ohio redesignation (65 FR at 37890, June 19, 2000), and in the Pittsburgh-Beaver Valley, Pennsylvania redesignation (66 FR at 53099, October 19, 2001).

EPA has reviewed the Idaho SIP and has concluded that it meets the general SIP requirements under Section 110(a)(2) of the CAA to the extent they are applicable for the purposes of redesignation. EPA has previously approved provisions of Idaho's SIP as demonstrating compliance with the CAA section 110(a)(2) requirements for the 2006 PM_2.5 NAAQS (79 FR 40662, July 14, 2014). These requirements are, however, statewide requirements that are not linked to the PM_2.5 nonattainment status of the Logan, UT-ID NAA. Therefore, EPA believes that these SIP elements are not applicable requirements for purposes of review of this proposed redesignation.

2. Part D of Title I Requirements

Part D of Title I of the CAA sets forth the basic nonattainment plan requirements applicable to all nonattainment areas at subpart 1 (CAA sections 172-176) and requirements specific to PM₁₀ and PM_2.5 areas at subpart 4 (CAA section 189). On August 24, 2016, EPA promulgated the Fine Particulate Matter National Ambient Air Quality Standards; State Implementation Plan Requirements rule. This rule implements the requirements of Part D of Title I of the CAA for areas designated nonattainment for any PM_2.5 NAAQS.

In accordance with 40 CFR 51.1015, upon a determination by EPA that a Moderate PM_2.5 nonattainment area has attained the PM_2.5 NAAQS, the requirements for the state to submit an attainment demonstration, provisions demonstrating that RACM (including RACT for stationary sources) shall be implemented no later than 4 years following the date of designation of the area, RFP plan, QMs and QM reports, and contingency measures for the area shall be suspended until such time as: (1) The area is redesignated to attainment, after which such requirements are permanently discharged; or, (2) EPA determines that the area has re-violated the PM_2.5 NAAQS.

Those states containing Moderate PM_2.5 NAAs were required to submit a SIP by December 31, 2014, which demonstrated attainment of the PM_2.5 NAAQS by December 31, 2015. Pursuant to CAA section 188(d) and 40 CFR 51.1005(a), on September 8, 2017, EPA extended the attainment date for the Logan UT-ID NAA from December 31, 2015 to December 31, 2017 (82 FR 42447). As stated in the “Background” section, EPA has approved several attainment plan elements for the Idaho portion of the Logan UT-ID area. Specifically, EPA approved the following elements of Idaho's attainment plan: Baseline emissions inventory (July 18, 2014, 79 FR 41904); control measures (March 25, 2014, 79 FR 16201); RACM/RACT (January 4, 2017, 82 FR 729); attainment demonstration (August 8, 2017, 82 FR 37025); nonattainment NSR (August 20, 2018, 83 FR 42033), and RFP, QM and MVEB (February 20, 2020, 85 FR 9664).

Pursuant to 40 CFR 51.1015(a), on October 19, 2018, EPA completed a CDD for the Logan, UT-ID Moderate PM_2.5 NAA. (83 FR 52983). The CDD suspended the obligation for Idaho to make submissions to meet certain CAA requirements related to attainment of the NAAQS, including the CAA section 172(c)(9) requirement to adopt contingency measures.

Determinations of attainment do not relieve states from submitting and EPA from approving certain Part D planning requirements for the 2006 PM_2.5 NAAQS. CAA section 172(c)(3) requires submission and approval of a comprehensive, accurate and current inventory of actual emissions. For purposes of the PM_2.5 NAAQS, this emissions inventory should address not only direct emissions of PM_2.5, but also emissions of all precursors to PM_2.5 formation, i.e., SO₂, NO_X, VOC, and ammonia. As previously discussed, EPA determined that Idaho met the CAA section 172(c)(3) comprehensive emissions inventory requirement in a final rulemaking on July 18, 2014 (79 FR 41904).

CAA section 172(c)(4) requires the identification and quantification of allowable emissions for major new and modified stationary sources in an area, and CAA section 172(c)(5) and requires source permits for the construction and operation of new and modified major stationary sources anywhere in the nonattainment area. EPA first approved the requirements of the part D NSR permit program for Idaho under subpart 1 on November 26, 2010 (75 FR 72719). Subsequently, on March 20, 2018, Idaho submitted rule revisions to meet additional part D NSR requirements promulgated by the EPA under subpart 4 (81 FR 58010, August 24, 2016). We approved Idaho's submission on August 20, 2018 (83 FR 42033).

Once the Logan, UT-ID PM_2.5 NAA is redesignated to attainment, the prevention of significant deterioration (PSD) requirements of part C of the Act will apply. Idaho's PSD regulations are codified in the Idaho Administrative Procedures Act (IDAPA) at 58.01.01.200-228 (permit to construct) and governed by IDAPA 58.01.01.205 (permit requirements for new major facilities or major modifications in attainment or unclassifiable areas). We most recently approved revisions to Idaho's PSD program on August 20, 2018 (83 FR 42033), May 12, 2017 (82 FR 22083) and August 12, 2016 (81 FR 53290). EPA finds that Idaho's PSD provisions meet all applicable Federal requirements for any area designated unclassifiable or attainment, and these provisions will become fully effective in the Idaho portion of the Logan, UT-ID PM_2.5 NAA upon redesignation of the area to attainment.

CAA section 172(c)(7) requires the SIP to meet the applicable provisions of CAA section 110(a)(2). As noted above, we find that the Idaho SIP meets the CAA section 110(a)(2) applicable requirements for purposes of redesignation.

For purposes of redesignation to attainment for the 2006 24-hour PM_2.5 NAAQS, EPA proposes to find that Idaho has met all the applicable SIP requirements under part D of Title I of the CAA.

3. Fully Approved SIP Under CAA Section 110(k)

As discussed in Sections III.B.1 and III.B.2 of this document, for purposes of redesignation to attainment for the 2006 24-hour PM_2.5 NAAQS, EPA has fully approved all applicable requirements of Idaho's SIP for the Idaho portion of the Logan UT-ID area in accordance with CAA section 110(k). Therefore, EPA has fully approved all applicable requirements of the applicable implementation plan in accordance with CAA section 110(k).

C. Improvement in Air Quality Due to Permanent and Enforceable Measures

CAA section 107(d)(3)(E)(iii) of the CAA provides that for an area to be redesignated to attainment, the Administrator must determine that the improvement in air quality is due to permanent and enforceable reductions in emissions resulting from implementation of the applicable implementation plan, implementation of applicable Federal air pollutant control regulations, and other permanent and enforceable reductions.

On December 14, 2012, IDEQ submitted an attainment plan that addressed attainment planning requirements for the Idaho portion of the Logan UT-ID PM_2.5 NAA. On December 24, 2014, the IDEQ submitted a supplement to the 2012 attainment plan that included additional analysis. Idaho's December 14, 2012, attainment plan submittal included residential wood combustion (RWC) ordinances, road-sanding agreements, and a wood stove change-out program to reduce emissions of PM_2.5 in the Idaho portion of the Logan UT-ID PM_2.5 NAA. Each of these programs is discussed in detail within this section. EPA approved the RWC ordinances and road sanding agreements into the Idaho SIP on March 25, 2014 (79 FR 16201), making them federally enforceable. EPA approved Idaho's evaluation of, and imposition of, RACM and RACT level controls on appropriate sources on January 4, 2017 (82 FR 729). This approval included approving the RWC ordinances and wood stove change-out program as meeting the RACM requirement.

The RWC ordinances approved as RACM on January 4, 2017, apply within Franklin County and all six Idaho cities on the Idaho side of the Logan UT-ID PM_2.5 NAA (Franklin, Preston, Weston, Dayton, Clifton, and Oxford). EPA determined in its approvals that these RWC ordinances achieved permanent and enforceable emissions reductions. Key elements in the current RWC ordinances include mandatory burn bans issued when PM_2.5 has reached or is forecasted to reach 75 on the Air Quality Index (AQI), which corresponds to a PM_2.5 concentration of 23.3 μg/m³ and aligns with the RWC ordinances applicable within Cache County on the Utah side of the Logan UT-ID PM_2.5 NAA. All RWC ordinances effective in Franklin County prohibit both open burning and the use of specified devices when an air quality alert is issued. The ordinances also prohibit the installation of non-EPA-certified devices. Each of the adopted ordinances bans open burning of any kind during burn ban days, bans the sale or installation of non-EPA certified devices in new or existing buildings, and prohibits the construction of any building for which a solid fuel burning device is the sole source of heat. In its December 14, 2012, attainment plan submittal, Idaho estimated that maximum reductions for this measure are 0.06 tons per day (tpd) direct PM_2.5, 0.009 tpd nitrogen oxides (NO_X), and 0.078 tpd volatile organic compounds (VOC).

In our March 25, 2014 action, EPA also approved road sanding agreements between IDEQ, Franklin County Road and Bridge, and the Idaho Transportation Department (IDT) to reduce the contribution of primary PM_2.5 from reentrained dust on paved roads. According to records submitted to Idaho and summarized in the submission, IDT used salt in 2014 (409 tons), 2015 (340 tons), and 2016 (109 tons) and did not use sand. Franklin County Road and Bridge historically used a 10:1 ratio of sand and salt; however, in the Idaho attainment plan, Franklin County committed to use a 4:1 ratio of sand and salt when anti-skid treatment is required. Franklin County also agreed to apply brine when temperatures are above 22 °F, a measure that further reduces the amount of sand required by approximately 50%. The City of Preston now uses a 2:1 ratio of sand and salt at an average of 700 tons total per year. In its SIP, IDEQ estimates that these road sanding commitments would lead to 0.10 tpd reduction in direct PM_2.5 annually.

Finally, in its attainment plan, IDEQ quantified the emission reduction benefits from three woodstove change-out programs on the Idaho side of the Logan UT-ID area. These programs were conducted in 2006-2007, 2011-2012, and 2013-2014. Accordingly, Idaho demonstrated in the submission that a total of 209 uncertified RWC devices have been changed-out since 2006. In addition, 39 stoves were removed and destroyed through Idaho's Alternative Energy Device tax deduction program. In total, 256 wood stoves have been changed out on the Idaho side of the Logan UT-ID NAA since 2006. As described in the supplemental 2014 attainment plan SIP submittal (applying the appropriate temporal profile to convert to tons per day), Idaho stated these change-outs have led to permanent reductions of 0.05 tpd direct PM_2.5, 0.003 tpd NO_X, and 0.13 tpd VOC. These woodstove change-out programs achieved permanent and enforceable emissions reductions because the RWC ordinances banned the sale or installation of non-EPA certified devices in new or existing buildings in Franklin County jurisdictions.

IDEQ also noted that Utah adopted permanent and enforceable control measures into its SIP that have reduced PM_2.5 and precursor emissions and led to the improvement in air quality in the Logan UT-ID PM_2.5 NAA. IDEQ specifically referenced area source rules (2015 reductions of 122 lbs/day NO_X, 679 lbs/day PM_2.5, 3,665 lbs/day VOC) and a vehicle and inspection and maintenance program (2015 reductions of 0.214 tons/day for NO_X and 0.212 tons/day for VOC) in the Utah portion of the Logan UT-ID NAA. IDEQ also referenced Federal measures, including the “Tier 3 Motor Vehicle Emission and Fuel Standards Rule” (79 FR 23414), as permanent and enforceable reductions leading to improvement in air quality, and ultimately to attainment, in the Logan UT-ID PM_2.5 NAA.

Based on the foregoing evaluation of these control measures, EPA proposes to determine that the improvement in air quality is reasonably attributable to permanent and enforceable reductions in emissions resulting from implementation of the applicable implementation plan, implementation of applicable Federal air pollutant control regulations, and other permanent and enforceable reductions.

D. Fully Approved Maintenance Plan

CAA section 107(d)(3)(E)(iv) requires that, for a NAA to be redesignated to attainment, EPA must fully approve a maintenance plan which meets the requirements of CAA section 175A. The plan must demonstrate continued attainment of the relevant NAAQS in the area for at least 10 years after our approval of the redesignation. Eight years after our approval of a redesignation, the State must submit a revised maintenance plan demonstrating attainment for the 10 years following the initial 10-year period. The maintenance plan must also contain a contingency plan to ensure prompt correction of any violation of the NAAQS. See CAA sections 175A(b) and (d). The Calcagni Memo provides additional guidance on the content of a maintenance plan, stating that a maintenance plan should include the following elements: (1) An attainment emissions inventory; (2) a maintenance demonstration showing attainment for 10 years following redesignation; (3) a commitment to maintain the existing monitoring network; (4) verification of continued attainment; and (5) a contingency plan to prevent or correct future violations of the NAAQS. The following paragraphs describe how each of these elements is addressed in Idaho's maintenance plan.

1. Attainment Inventory

As discussed in the General Preamble (see 57 FR 13498, April 16, 1992) and the Calcagni Memo, PM_2.5 maintenance plans should include an attainment emission inventory to identify the level of emissions in the area which is sufficient to maintain the NAAQS.

The maintenance plan attainment year inventory should include the emissions during the time period associated with the monitoring data showing attainment. For the Logan, UT-ID PM_2.5 NAA, IDEQ determined attainment using air quality data from 2015, 2016, and 2017, the design value period relied upon for the EPA's Determination of Attainment (83 FR 52983, October 19, 2018). The State therefore used 2017 to calculate its base year attainment inventory, which aligned with the 2017 National Emissions Inventory (NEI) data available for point, area, on-road mobile, and nonroad mobile sources. IDEQ then projected the 2017 base year inventory to both a “horizon year” (a future year at least 10 years from the approval date of the maintenance plan) of 2031 and an interim year of 2026.

The NEI is compiled at the county level, so the State first calculated the 2017 emissions inventories for Franklin County, and then apportioned these county-wide inventories to the portion of Franklin County included in the Logan, UT-ID NAA. IDEQ projected mobile source emissions using the latest version of EPA's Motor Vehicle Emissions Simulator (MOVES) model (MOVES2014b). IDEQ used apportioned 2017 NEI data for the on-road mobile source emissions, and used MOVES2014b model defaults for the nonroad portion of the model, because the State has not yet developed input files for that version of the model. To best represent emissions that occur on days when the ambient concentrations of PM_2.5 are of concern, the MOVES meteorological inputs were based on an average episodic day representing conditions present during wintertime stagnation events leading to high levels of ambient PM_2.5 in the Logan UT-ID PM_2.5 NAA. IDEQ ran MOVES2014b to calculate on-road and nonroad mobile source emissions on an average episodic winter day for Franklin County for January 2017, 2026 and 2031. Area source emissions were apportioned from 2017 NEI data for individual categories, which were projected for the 2026 and 2031 inventories based on an average annual growth rate. No point sources were listed in the base year or projected future inventories. More detailed descriptions of the 2017 base year inventory and the 2026 and 2031 projected inventories can be found in section 4 and Appendix A of Idaho's September 13, 2019 submittal, in the docket for this action.

For each of these source categories, the pollutants that were inventoried include: PM_2.5, sulfur dioxide (SO₂), NO_X, VOC, and ammonia (NH₃). Summary of emission figures from 2017 base year and the projected inventories are provided in Table 3 of this document.

Following our review, we have determined that IDEQ prepared an adequate attainment inventory for the Idaho portion of the Logan, UT-ID PM_2.5 NAA.

In the September 13, 2019 submission, Idaho also provided inventory information for the Utah portion of the Logan, UT-ID NAA. Idaho derived this inventory from the Utah Division of Air Quality (Utah DAQ), which performed a photochemical grid modeling analysis using the “Comprehensive Air Quality Model with Extensions” (v. 6.3, http://www.camx.com/ ) modeling system for the nonattainment area for Utah's attainment, interim, and projected years. Utah used linear projections to estimate future years to 2035. Utah DAQ's modeling domain included all three of the nonattainment areas in UT and extended into southern Idaho to include the Idaho portion of the Logan UT-ID PM_2.5 NAA. The methodology for the mobile, nonroad and area source emissions inventories can be found in the Utah DAQ PM_2.5 Emissions Inventory Preparation Plan (Utah DAQ 2019), in the docket for this action. IDEQ interpolated the Utah DAQ projections to 2031 using the average annual growth rate for area, mobile, and nonroad sources to match the 2031 horizon year for Idaho's redesignation request. The actual and projected emissions in the Utah portion of the Logan UT-ID PM_2.5 NAA are provided in Table 4 of this document. Table 5 of this document provides Idaho's projected emissions inventories for the entire Logan UT-ID PM_2.5 NAA, which is the combination of the values in Tables 3 and 4 of this document.

Based our review of the emissions inventories Idaho provided in its September 13, 2019 submittal, shown in Tables 3 through 5 of this document, we propose to find that Idaho prepared an adequate attainment inventory for the Logan, UT-ID PM_2.5 NAA.

2. Maintenance Demonstration

CAA section 175A requires a state seeking redesignation to attainment to submit a SIP revision to provide for the maintenance of the NAAQS in the area “for at least 10 years after the redesignation.” A state can make this demonstration by either showing that future emissions of a pollutant or its precursors will not exceed the level of the attainment inventory, or by modeling to show that the future mix of sources and emissions rates will not cause a violation of the NAAQS. See Calcagni Memo, pages 9-10. Idaho elected to demonstrate maintenance of the 2006 PM_2.5 NAAQS for at least ten years following redesignation using the attainment inventory method.

IDEQ developed projected inventories, provided in Tables 3 through 5 of this document, to show that the Logan UT-ID area will remain in attainment through the year 2031. These projected inventories, covering an interim year of 2026 and a horizon year of 2031, show that future emissions of NO_X, SO₂, VOCs, ammonia, and direct PM_2.5 throughout the NAA will remain at or below the 2017 attainment-level emissions for the 2006 24-hour PM_2.5 NAAQS. As these inventories show, emissions from NO_X, SO₂, VOCs and NH₃ are projected to decrease between 2017 and 2031 (Table 5 of this document). The emissions of direct filterable PM_2.5 are projected to decline by 5.4% by 2031 (Table 5 of this document).

Although emissions from condensable PM_2.5 increase by 6.1% by 2031, Idaho adequately demonstrated that this increase will not prevent maintenance of the NAAQS through 2031. The condensable fraction of PM_2.5 is 0.6% of the total PM_2.5-Primary levels projected for 2031. As depicted in Table 5 of this document, the total condensable PM_2.5 emissions are projected to increase by 0.71 pounds per winter day between 2017 and 2031, while total filterable PM_2.5 emissions are projected to decrease by 119.72 pounds per winter day over the same time period. Overall, total PM_2.5 (sum of filterable and condensable PM_2.5) is projected to decrease by 5.3% from 2017 to 2031.

EPA has reviewed the documentation provided by Idaho for developing the 2026 and 2031 emissions inventories for the Logan UT-ID PM_2.5 NAA. Based on our review, EPA finds that the emissions inventories were prepared in accordance with EPA requirements. These inventories indicate a decrease in PM_2.5 and precursor emissions throughout the maintenance period, therefore EPA is proposing to determine that the projected emissions inventories in the Idaho maintenance plan sufficiently demonstrate that the Logan UT-ID PM_2.5 NAA will continue to maintain the 2006 24-hour PM_2.5 standard throughout the maintenance period.

3. Monitoring Network

Once a NAA has been redesignated to attainment, the state must continue to operate an appropriate air quality monitoring network, in accordance with 40 CFR part 58, to verify the attainment status of the area. The maintenance plan should contain provisions for continued operation of air quality monitors that will provide such verification. In the maintenance plan, IDEQ noted that it currently operates a regulatory monitor (the Preston monitor) in the Idaho portion of the Logan, UT-ID PM_2.5 NAA, and committed to continue operating a regulatory monitoring network in Franklin County in order to verify continued attainment of the PM_2.5 NAAQS and track the progress of the maintenance plan. IDEQ also stated that it will work with EPA each year through the air monitoring network review process (per 40 CFR part 58) to determine the adequacy of the monitoring network. EPA proposes to determine that the maintenance plan contains adequate provisions for continued operation of an air quality monitoring network to verify maintenance of the 2006 PM_2.5 NAAQS.

4. Verification of Continued Attainment

As stated in Section III.D.3 of this document, in its maintenance plan, Idaho commits to continue to operate a regulatory monitoring network in order to verify continued attainment of the PM_2.5 NAAQS in the Idaho portion of the Logan UT-ID area. Idaho is also required to periodically update the emissions inventory for Franklin County in accordance with the Annual Air Emissions Reporting Requirements Rule (AERR) during the maintenance plan period. This includes developing annual inventories for major point sources and a comprehensive periodic inventory covering all source categories every three years.

5. Contingency Plan

CAA section 175A(d) requires that a maintenance plan also include contingency provisions, as necessary, to promptly correct any violation of the NAAQS that occurs after redesignation of the area to attainment. For the purposes of CAA section 175A, a state is not required to have fully adopted contingency measures that will take effect without further action by the state in order for the maintenance plan to be approved. However, the contingency plan is an enforceable part of the SIP and should ensure that contingency measures are adopted expeditiously once they are triggered. The plan should discuss the measures to be adopted and a schedule and procedure for adoption and implementation. The contingency plan must require that the state will implement all measures contained in the Part D nonattainment plan for the area prior to redesignation. The state should also identify the specific indicators, or triggers, which will be used to determine when the contingency plan will be implemented.

Idaho's maintenance plan outlines the procedures for the adoption and implementation of contingency measures to further reduce emissions should a violation occur. Idaho's contingency measures include a warning level response and an action level response. An initial warning level response is triggered for the 2006 24-hour PM_2.5 NAAQS when the 98th percentile 24-hour PM_2.5 concentration for a single calendar year reaches 35.5 µg/m³ or greater within the area. An action level response will be prompted by any one of the following: (1) A two year average of the 98th percentile reaches 35.5 µg/m³ or greater within the area; or (2) a violation of the standard occurs in the area (i.e. a three-year average of the 98th percentile reaches 35.5 µg/m³ or greater).

Regardless of which level of response is triggered, the State will evaluate all appropriate data including air quality data, evaluation of wood smoke programs and information on wildfires or winter power outages to determine the cause of the exceedance. IDEQ will perform this evaluation within six months of the end of the year in which the NAAQS is exceeded or violated. Should a warning level response be triggered, and IDEQ determines that additional emissions reductions are necessary, the State will adopt and implement contingency measures as expeditiously as possible and no later than 18 months from the determination of a single year exceedance based on quality assured data. Should an action level response be triggered, implementation of necessary control measures will take place as expeditiously as possible, but in no event later than 18 months after IDEQ determines, based on quality-assured ambient data, that an action level trigger has been exceeded.

Idaho has identified the following potential contingency measures for the maintenance plan:

• Measures to address emissions from residential wood combustion, including the potential implementation of a burn ban in the maintenance area at a lower threshold than currently in place in the ordinances for the six cities in the Idaho portion of the Logan UT-ID PM_2.5 NAA. The current ordinances trigger a burn ban when the Air Quality Index (AQI) level reaches 75.
• Additional measures to address other PM_2.5 sources identified in the emissions inventory such as on-road and nonroad vehicles, industrial sources, and dust.

Based on our analysis of Idaho's submittal, we propose to find that the contingency measure provisions provided in Idaho's Logan, UT-ID PM_2.5 maintenance plan are sufficient and meet the requirements of CAA section 175A(d).

E. Requirements for Transportation Conformity and Motor Vehicle Emissions Budgets (MVEBs).

Transportation conformity is required by CAA section 176(c). EPA's conformity rule at 40 CFR part 93, subpart A requires that transportation plans, programs, and projects conform to SIPs and establishes the criteria and procedures for determining whether or not they conform. Conformity to a SIP means that transportation activities will not produce new air quality violations, worsen existing violations, or delay timely attainment of the NAAQS. Thus, EPA's conformity rule requires a demonstration that emissions from a Metropolitan Planning Organization's (MPO's) Regional Transportation Plan and Transportation Improvement Program, involving Federal Highway Administration (FHWA) or Federal Transit Administration (FTA) funding or approval, are consistent with the MVEB(s) contained in a control strategy SIP revision or maintenance plan (40 CFR 93.101, 93.118, and 93.124). A MVEB is the level of mobile source emissions of a pollutant relied upon in the attainment or maintenance demonstration to attain or maintain compliance with the NAAQS in the nonattainment or maintenance area.

A PM_2.5 maintenance plan should identify MVEBs for direct PM_2.5, NO_X and all other PM_2.5 precursors from on-road mobile source emissions that are determined to significantly contribute to PM_2.5 levels in the area. To determine which precursor pollutants are required to have an MVEB, IDEQ reviewed PM_2.5 speciation at the Franklin monitor. Based on PM_2.5 speciation data and the local emissions inventory composition for each pollutant, IDEQ determined that in addition to NO_X and direct PM_2.5, the maintenance plan should also include an MVEB for VOCs because they are important precursors to secondary formation PM_2.5. The State excluded direct PM_2.5 emissions from paved road dust from the MVEBs in accordance with 40 CFR 93.102(b)(3), as these emissions made up only 1% of total wintertime contributions at the Franklin monitor. Vehicle emissions of SO₂ and NH₃ were also found to contribute minimally to PM_2.5 in the area and therefore the maintenance plan does not include MVEBs for these precursors in accordance with 40 CFR 93.102(b)(2)(v). See Section 6 of Idaho's maintenance plan, in the docket for this action, for further analysis of the pollutants and precursors and the decisions on whether or not MVEBs were required for the individual pollutants and precursors.

The MVEBs for 2031 are identical to the on-road mobile source emissions inventory provided for direct PM_2.5, NO_X and VOCs in Table 1 (in Section II.D.1 of this document) of this proposed action for that year, except that the 2031 direct PM_2.5 budget does not include paved road dust. As stated in that section, IDEQ used EPA's MOVES2014b model to develop vehicle emissions estimates for 2031, which were recalculated into tons per day (from lbs per day) for the 2031 MVEBs.

Based on its analysis, IDEQ set the mobile source emissions budgets for 2031 provided in Table 6 of this proposed action, as part of the September 13, 2019 maintenance plan submission. The previously approved 2017 MVEBs (see 85 FR 9664, February 20, 2020), are included in Table 6. According to EPA's conformity rule, the emissions budget acts as a ceiling on emissions in the year for which it is defined or until a SIP revision modifies the budget.

We propose to find that Idaho has evaluated the appropriate pollutants and precursors and appropriately established MVEBs for direct PM_2.5, NO_X and VOCs. Idaho used the most up-to-date model (MOVES2014b) available at the time of submission in order to appropriately calculate these budgets. The MVEBs are based on the control measures in the maintenance plan and consistent with maintaining the 2006 24-hour PM_2.5 NAAQS. Based on our review of Idaho's 2031 MVEBs, we are proposing to approve the budgets.

IV. Proposed Action

EPA is proposing to redesignate the Idaho portion of the Logan UT-ID PM_2.5 NAA, and proposing to approve the associated maintenance plan for the area. If this proposal is finalized, the designation status of the Idaho portion of the Logan, UT-ID PM_2.5 NAA under 40 CFR part 81 will be revised to attainment upon the effective date of that final action.

V. Statutory and Executive Order Reviews

Under the CAA, redesignation of an area to attainment and the accompanying approval of a maintenance plan under section 107(d)(3)(E) are actions that affect the status of a geographical area and do not impose any additional regulatory requirements on sources beyond those imposed by state law. A redesignation to attainment does not in and of itself create any new requirements, but rather results in the applicability of requirements contained in the CAA for areas that have been redesignated to attainment. Moreover, the Administrator is required to approve a SIP submission that complies with the provisions of the CAA and applicable Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP submissions, EPA's role is to approve state choices, provided that they meet the criteria of the CAA. Accordingly, this action merely approves state law as meeting Federal requirements and does not impose additional requirements beyond those already imposed by state law. For that reason, this action:

• Is not a “significant regulatory action” subject to review by the Office of Management and Budget under Executive Orders 12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
• Is not an Executive Order 13771 (82 FR 9339, February 2, 2017) regulatory action because SIP approvals are exempted under Executive Order 12866;
• Does not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
• Is certified as not having a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 601 et seq.);
• Does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4);
• Does not have federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999);
• Is not an economically significant regulatory action based on health or safety risks subject to Executive Order 13045 (62 FR 19885, April 23, 1997);
• Is not a significant regulatory action subject to Executive Order 13211 (66 FR 28355, May 22, 2001);
• Is not subject to requirements of Section 12(d) of the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) because application of those requirements would be inconsistent with the CAA; and
• Does not provide EPA with the discretionary authority to address, as appropriate, disproportionate human health or environmental effects, using practicable and legally permissible methods, under Executive Order 12898 (59 FR 7629, February 16, 1994).

In addition, the SIP is not approved to apply on any Indian reservation land or in any other area where EPA or an Indian tribe has demonstrated that a tribe has jurisdiction. In those areas of Indian country, this rule does not have tribal implications as specified by Executive Order 13175 (65 FR 67249, November 9, 2000), because redesignation is an action that affects the status of a geographical area and does not impose any new regulatory requirements on tribes, impact any existing sources of air pollution on tribal lands, nor impair the maintenance of ozone national ambient air quality standards in tribal lands.

List of Subjects

40 CFR Part 52

• Environmental protection
• Air pollution control
• Incorporation by reference
• Intergovernmental relations
• Lead
• Nitrogen dioxide
• Ozone
• Particulate matter
• Reporting and recordkeeping requirements
• Sulfur oxides
• Volatile organic compounds

40 CFR Part 81

• Environmental protection
• Air pollution control
• National parks
• Wilderness areas

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