Document ID: EPA-R08-OAR-2020-0021-0001
Agency: epa
Document Type: Proposed Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: Utah; Logan, Utah-Idaho PM2.5 Redesignation to Attainment, Maintenance Plan, and Rule Revisions
Posted Date: 2021-02-26T05:00Z

[Federal Register Volume 86, Number 37 (Friday, February 26, 2021)]
[Proposed Rules]
[Pages 11694-11707]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-03819]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R08-OAR-2020-0021; FRL-10020-28-Region 8]

Approval and Promulgation of Implementation Plans; State of Utah; 
Logan, Utah-Idaho PM2.5 Redesignation to Attainment, Maintenance Plan, 
and Rule Revisions

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve the request by the State of Utah to redesignate the Logan, 
Utah-Idaho (UT-ID) nonattainment area (NAA) (``Logan NAA'') to 
attainment status for particulate matter with an aerodynamic diameter 
less than or equal to a nominal 2.5 microns (PM2.5), and to 
approve related State Implementation Plan (SIP) revisions submitted by 
the State of Utah on November 5, 2019, and January 13, 2020. The 
redesignation request documents that the area has attained the 2006 
PM2.5 National Ambient Air Quality Standards (NAAQS) and 
provides supporting information. The November 5, 2019 submittal 
includes revisions to Utah's R307-110-31 and R307-110-36 rules, 
concerning SIP Sections X.A and X.F. The January 13, 2020 submittal 
includes revisions to UAC R307-110-10 and the maintenance plan for the 
Logan NAA, which demonstrates attainment through the year 2035. The EPA 
is taking this action pursuant to the Clean Air Act (CAA or the Act). A 
separate EPA redesignation rulemaking will be conducted for the Idaho 
portion of the Logan NAA.

DATES: Written comments must be received on or before March 29, 2021.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R08-
OAR-2020-0021, to the Federal Rulemaking Portal: https://www.regulations.gov. Follow the online instructions for submitting 
comments. Once submitted, comments cannot be edited or removed from 
www.regulations.gov. The EPA may publish any comment received to its 
public docket. Do not submit electronically any information you 
consider to be Confidential Business Information (CBI) or other 
information whose disclosure is restricted by statute. Multimedia 
submissions (audio, video, etc.) must be accompanied by a written 
comment. The written comment is considered the official comment and 
should include discussion of all points you wish to make. The EPA will 
generally not consider comments or comment contents located outside of 
the primary submission (i.e., on the web, cloud, or other file sharing 
system). For additional submission methods, the full EPA public comment 
policy, information about CBI or multimedia submissions, and general 
guidance on making effective comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.
    Docket: All documents in the docket are listed in the 
www.regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, will be publicly available only in hard copy. 
Publicly available docket materials are available electronically in 
www.regulations.gov. To reduce the risk of COVID-19 transmission, for 
this action we do not plan to offer hard copy review of the docket. 
Please email or call the person listed in the FOR FURTHER INFORMATION 
CONTACT section if you need to make alternative arrangements for access 
to the docket.

FOR FURTHER INFORMATION CONTACT: Crystal Ostigaard, Air and Radiation 
Division, Environmental Protection Agency (EPA), Region 8, Mailcode 
8ARD-QP, 1595 Wynkoop Street, Denver, Colorado 80202-1129, (303) 312-
6602, ostigaard.crystal@epa.gov.

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

I. Background

A. Statutory and Regulatory Background for EPA's Regulation of PM2.5

    Under section 109 of the Act, the EPA has promulgated NAAQS for 
certain pollutants, including PM2.5. Once the EPA 
promulgates a NAAQS, section 107 of the Act specifies a process for the 
designation of each area within a state, generally as either an 
attainment area (an area attaining the NAAQS) or as a NAA (an area not 
attaining the NAAQS, or that contributes to nonattainment of the NAAQS 
in a nearby area). For PM2.5, certain areas have also been 
designated ``unclassifiable.'' These various designations, in turn, 
trigger certain state planning requirements.
    For all areas, regardless of designation, section 110 of the Act 
requires that each state adopt and submit for EPA approval a plan to 
provide for implementation, maintenance, and enforcement of the NAAQS. 
This plan is commonly referred to as a SIP. Section 110 contains 
requirements that a SIP must meet to gain EPA approval.\1\ For NAAs, 
SIPs must meet additional requirements in part D of Title I of the Act. 
Usually, SIPs include measures to control emissions of air pollutants 
from various sources, including stationary, mobile, and area sources. 
For example, a SIP may specify emission limits at power plants or other 
industrial sources.
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    \1\ EPA's approval of a SIP has several consequences. For 
example, after the EPA approves a SIP, the EPA and citizens may 
enforce the SIP's requirements in federal court under section 113 
and section 304 of the Act; in other words, the EPA's approval of a 
SIP makes the SIP ``federally enforceable.'' Also, once the EPA has 
approved a SIP, a state cannot unilaterally change the federally 
enforceable version of the SIP. Instead, the state must first submit 
a SIP revision to the EPA and gain EPA's approval of that revision.
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    On October 17, 2006 (71 FR 61144), the EPA revised the level of the 
24-hour PM2.5 NAAQS, lowering the primary and secondary 
standards from the 1997 standard of 65 micrograms per cubic meter 
([micro]g/m\3\) to 35 [micro]g/m\3\. On

[[Page 11695]]

November 13, 2009 (74 FR 58688), the EPA designated three areas in Utah 
as Moderate NAAs for the 2006 24-hour PM2.5 NAAQS of 35 
[micro]g/m\3\: The Salt Lake City, Provo, and Logan NAAs.
    The Logan NAA is composed of portions of Cache County, UT and 
Franklin County, ID. The Cache Valley is an isolated, bowl-shaped 
valley measuring approximately 60 kilometers north to south and 20 
kilometers east to west, 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. The 
State of Utah views topography as a barrier to air movement during the 
conditions that lead to elevated concentrations of fine particulates, 
and as the primary factor in determining where the population is 
located. The low-lying valleys that trap air during wintertime 
temperature inversions are also the regions where most people live. 
Additional information pertaining to the unique issues associated with 
the Logan NAA and studies completed on inversions can be found in the 
9-factor analysis for Utah and Idaho in the November 13, 2009 (74 FR 
58688) action, ``Air Quality Designations for the 2006 24-Hour Fine 
Particulate (PM2.5) National Ambient Air Quality 
Standards.''
    The EPA issued a rule in 2007 \2\ regarding implementation of the 
2006 24-hour PM2.5 NAAQS for the NAA requirements specified 
in CAA title I, part D, subpart 1. Under subpart 1, Utah was required 
to submit an attainment plan for each area no later than three years 
from the date of nonattainment designation, addressing the requirements 
listed in section 172 of the Act. These plans needed to provide for the 
attainment of the PM2.5 standards as expeditiously as 
practicable, but no later than five years from the date the areas were 
designated nonattainment.
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    \2\ 72 FR 20586 (Apr. 25, 2007).
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    In 2013, the U.S. Court of Appeals for the District of Columbia 
held that the EPA should have implemented the 2006 PM2.5 24-
hour standards, as well as the other PM2.5 NAAQS, based on 
both subpart 1 (sections 171-179B) and subpart 4 (sections 188-190) of 
CAA title I, part D.\3\ Under subpart 4, all NAAs are initially 
classified as Moderate, and Moderate area attainment plans must address 
the requirements of subpart 4 as well as subpart 1. Additionally, 
subpart 4 sets a different SIP submittal due date and attainment year. 
For a Moderate area, the attainment SIP is due 18 months after 
designation and the attainment year is as expeditiously as practicable, 
but no later than the end of the sixth calendar year after designation. 
Therefore, as a result of the 2013 NRDC decision the State of Utah was 
required to submit an attainment plan addressing subpart 4 requirements 
in addition to subpart 1. EPA established the related deadlines in the 
Identification of Nonattainment Classification and Deadlines for 
Submission of State Implementation Plan (SIP) Provisions for the 1997 
Fine Particulate (PM2.5) National Ambient Air Quality 
Standard (NAAQS) and 2006 24-hour PM2.5 NAAQS rule, 
published on June 2, 2014 (79 FR 31566). This rule classified as 
Moderate the areas that were designated in 2009 as nonattainment and 
set the attainment SIP submittal due date for those areas at December 
31, 2014. Additionally, this rule established the Moderate area 
attainment date as December 31, 2015.
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    \3\ Nat. Res. Def. Council v. EPA, 706 F.3d 428, 437 (D.C. Cir. 
2013) (NRDC).
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    Under subparts 1 and 4, the State was required to include the 
following elements in its Moderate attainment plan:
    1. A comprehensive, accurate, current inventory of actual emissions 
from all sources of PM2.5 and PM2.5 precursors in 
the area. CAA section 172(c)(3).
    2. Provisions to assure that reasonably available control measures 
(RACM), including reasonably available control technologies (RACT), for 
the control of direct PM2.5 and PM2.5 precursors, 
shall be implemented no later than four years after the area is 
designated. CAA sections 172(c)(1) and 189(a)(1)(C).
    3. A demonstration (including air quality modeling) that the plan 
provides for attainment as expeditiously as practicable but no later 
than the Moderate area attainment date. CAA section 188(c)(1).
    4. Plan provisions that require reasonable further progress (RFP). 
CAA section 172(c)(2).
    5. Quantitative milestones, which are to be achieved every three 
years until the area is redesignated to attainment, and which 
demonstrate RFP toward attainment by the applicable date. The State is 
required to submit, not later than 90 days after the date on which a 
milestone applicable to the area occurs, a demonstration that all 
measures in the approved SIP have been implemented and the milestone 
has been met. CAA section 189(c); 40 CFR 51.1013(b). These submissions 
are referred to as ``quantitative milestone reports.''
    6. Provisions to assure that control requirements applicable to 
major stationary sources of PM2.5 also apply to major 
stationary sources of PM2.5 precursors, except where the 
state demonstrates to the EPA's satisfaction that such sources do not 
contribute significantly to PM2.5 levels that exceed the 
standard in the area. CAA section 189(e).
    7. Contingency measures to be implemented if the area fails to meet 
RFP or fails to attain by the applicable attainment date. CAA section 
172(c)(9).
    8. A revision to the Nonattainment New Source Review (NNSR) program 
to set the applicable ``major stationary source'' thresholds to 100 
tons per year (tpy). CAA section 302(j). Moderate area 2006 24-hour 
PM2.5 attainment plans must also satisfy the general 
requirements applicable to all SIP submissions under section 110 of the 
CAA, including the requirement to provide necessary assurances that the 
implementing agencies have adequate personnel, funding, and authority 
under CAA section 110(a)(2)(E), and the requirements concerning 
enforcement in CAA section 110(a)(2)(C).
    On August 24, 2016 (81 FR 58010), the EPA finalized the Fine 
Particulate Matter National Ambient Air Quality Standards: State 
Implementation Plan Requirements rule (``PM2.5 Requirements 
Rule''), which further addressed the 2013 NRDC decision. The final 
PM2.5 Requirements Rule details how air agencies can meet 
the SIP requirements under subparts 1 and 4, such as general 
requirements for attainment plan due dates and attainment 
demonstrations; provisions for demonstrating RFP; quantitative 
milestones; contingency measures; NNSR permitting programs; and RACM 
(including RACT).

B. Utah's PM2.5 Attainment and SIP Status

    On September 8, 2017 (82 FR 42447), the EPA granted two one-year 
extensions to the Moderate attainment date for the 2006 24-hour 
PM2.5 Logan NAA. The Moderate attainment date was originally 
December 15, 2015, and the granting of these two extensions changed the 
attainment date to December 31, 2017.
    On October 19, 2018 (83 FR 52983), the EPA finalized a 
determination that the Logan PM2.5 NAA had attained the 2006 
primary and secondary 24-hour PM2.5 NAAQS by the December 
31, 2017 attainment date. Additionally, the EPA finalized a 
determination that the obligation to submit several remaining 
attainment-related SIP revisions arising from classification of the 
area as a Moderate NAA under subpart 4 of part D (of title I of the 
Act) for the 2006 24-hour PM2.5 NAAQS is not applicable

[[Page 11696]]

under the Clean Data Policy \4\ for so long as the area continues to 
attain the 2006 24-hour PM2.5 NAAQS. After this 
determination, the State of Utah was no longer obligated to submit an 
attainment demonstration, a demonstration that RACM (including RACT) 
shall be implemented no later than 4 years following the date of 
designation of the area, a RFP plan, quantitative milestones and 
quantitative milestone reports, and contingency measures. The State's 
remaining obligations include a baseline emissions inventory and a 
revised NNSR threshold. Also, for the Logan area to be redesignated to 
attainment, the State of Utah must still meet the statutory 
requirements for redesignation,\5\ as described in the EPA's 
``Procedures for Processing Requests to Redesignate Areas to 
Attainment'' guidance document.\6\
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    \4\ In designated nonattainment areas where monitored data 
demonstrate that the NAAQS have been achieved, the EPA interprets 
the CAA to provide that some of its requirements as no longer 
applicable as long as air quality continues to meet the standard. 
This CAA interpretation is known as the Clean Data Policy. As 
relevant to PM2.5 areas, this policy is reflected in EPA 
regulations at 40 CFR 51.1015.
    \5\ CAA Section 107(d)(3)(E).
    \6\ Memorandum from John Calcagni, Director, Air Quality 
Management Division (Sep. 4, 1992) (the Calcagni Memorandum; 
available at https://www.epa.gov/sites/production/files/2016-03/documents/calcagni_memo_-_procedures_for_processing_requests_to_redesignate_areas_to_attainment_090492.pdf).
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    The suspension of planning requirements pursuant to 40 CFR 51.1015 
does not preclude the State from submitting suspended elements of its 
Moderate area attainment plan, nor does it preclude the EPA from 
approving suspended elements, for the purpose of strengthening the SIP. 
Accordingly, the EPA approved portions of the Logan NAA SIP on October 
24, 2018 and November 23, 2018. On October 24, 2018, the EPA determined 
that the 2017 quantitative milestone report for the Logan 
PM2.5 NAA was adequate, which satisfied the quantitative 
milestone report requirement of CAA section 189(c) and 40 CFR 
51.1013(b). The determination letter from the EPA Administrator to the 
Governor of Utah is in the docket for this action.
    Finally, on November 23, 2018, the EPA approved portions of the 
Logan PM2.5 SIP (83 FR 59315) contained in Utah 
Administrative Code (UAC) R307-110-10, Section IX, Control Measures for 
Area and Point Sources, Part A, Fine Particulate Matter. The portions 
of the SIP that were approved include: (1) The emission inventory 
(satisfying the inventory requirement of CAA section 172(c)(3)); (2) 
modeled attainment demonstration; (3) determination for Major 
Stationary Source RACT; (4) determination for On-Road Mobile Sources 
RACM; (5) the state's determination that the previously approved \7\ 
Cache County Inspection and Maintenance (I/M) Program constituted 
additional RACM; (6) determination for Off-Road Mobile Sources RACM; 
and (7) 2015 Motor Vehicle Emission Budgets (MVEB). Additionally, R307-
110-10 incorporates by reference (IBRs) Utah SIP Section IX, Control 
Measures for Area and Point Sources, Part A, Fine Particulate Matter.
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    \7\ See 80 FR 54237 (Sep. 9, 2015).
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    On July 25, 2019 (84 FR 35832), the EPA approved revisions to R307-
403, Permits: New and Modified Sources in Nonattainment Areas and 
Maintenance Areas. This rule covers the CAA's NNSR requirements for 
PM2.5 NAAs. In Section II.B. below we briefly discuss this 
NNSR requirement and how the July 25, 2019 action addresses it as to 
the Logan NAA.

C. Redesignation Requests and Related Requirements

    For a NAA to be redesignated to attainment, the following 
conditions in section 107(d)(3)(E) of the CAA must be met:
    1. We must determine that the area has attained the NAAQS;
    2. The applicable implementation plan for the area must be fully 
approved under section 110(k) of the Act;
    3. We 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 and applicable 
Federal air pollutant control regulations and other permanent and 
enforceable reductions;
    4. We must fully approve a maintenance plan for the area as meeting 
the requirements of CAA section 175A; and
    5. The state containing the area must meet all requirements 
applicable to the area under section 110 and part D of the CAA.
    In the Calcagni Memorandum the Agency explains how it assesses the 
adequacy of redesignation requests against the conditions listed above.
    On January 13, 2020, the Governor of Utah submitted revisions to 
the SIP for R307-110-10, a maintenance plan for the Logan area (Utah 
SIP Section IX.A.28), and a request that the EPA redesignate this area 
to attainment for the 2006 24-hour PM2.5 NAAQS. R307-110-10 
IBRs Section IX, Control Measures for Area and Point Sources, Part A, 
Fine Particulate Matter; which formally incorporates the Logan 2006 24-
hour PM2.5 Maintenance Plan (located within the Utah SIP at 
Section IX.A.28) into Utah's State regulations. In Section II.C below, 
we discuss our review of the Utah Division of Air Quality (UDAQ) 
maintenance plan and redesignation request for the Logan 2006 24-hour 
PM2.5 NAAs.

II. The EPA's Evaluation

A. Utah's SIP Revisions

    When the Utah SIP is amended by the Utah Air Quality Board (UAQB), 
the amended sections must be incorporated into the Utah Air Quality 
Rules. Utah incorporates SIP sections into the State's rule R307-110. 
These rules are amended as needed to change the effective dates to 
match the UAQB approval date of various amendments to the Utah SIP. In 
this action we are proposing to approve submitted revisions to: (1) 
R307-110-10, which IBRs Section IX, Control Measures for Area and Point 
Sources, Part A, Fine Particulate Matter, and thus incorporates the 
Logan 2006 24-hour PM2.5 maintenance plan into State 
regulations (located within the Utah SIP at Section IX.A.28); and (2) 
R307-110-31 and R307-110-36, which IBR Section X, Vehicle Inspection 
and Maintenance Program, Part A, General Requirements and 
Applicability, and Section X, Vehicle Inspection and Maintenance 
Program, Part F, Cache County, which incorporate the general 
requirements and applicability of the I/M Programs in the State of Utah 
and the I/M Program of Cache County into the State regulations. Our 
evaluation of these revisions follows.
1. R307-110-10
    Section R307-110-10 incorporates amendments to Utah SIP Section 
IX.A into State regulations, thereby making them effective as a matter 
of State law. This is a ministerial provision, which only revises the 
effective date within the rule to December 4, 2019 and does not itself 
include any SIP measures.
2. R307-110-31
    Section R307-110-31 incorporates the amendments to Utah SIP Section 
X, Vehicle Inspection and Maintenance Program, Part A, General 
Requirements and Applicability, into State rules, thereby making them 
effective as a matter of State law. This is a ministerial provision, 
which only revises the effective date within the rule to September 4, 
2019 and does not itself include any control measures.
3. R307-110-36
    Section R307-110-36 incorporates the amendments to Utah SIP Section 
X,

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Vehicle Inspection and Maintenance Program, Part F, Cache County, into 
State rules, thereby making them effective as a matter of State law. 
This is a ministerial provision, which only revises the effective date 
within the rule to September 4, 2019 and does not itself include any 
control measures.
4. Subsection X, Vehicle Inspection and Maintenance Program, Part A, 
General Requirements and Applicability
    The revisions to ``Part A, General Requirements and Applicability'' 
include additions to section ``1. General Requirements'' that address 
the following revisions to Utah Code Annotated (UCA) Section 41-6a-
1642:
    a. An amendment in 2013 to include the date that notice is required 
and the date the enactment, change, or repeal will take effect if a 
county legislative body enacts, changes, or repeals the local emissions 
compliance fee. Section 41-6a-1642 provides that for a county that is 
required to implement a new vehicle emissions I/M program, but for 
which no current federally approved SIP exists, a vehicle shall be 
tested at a frequency determined by the county legislative body, in 
consultation with the UAQB, that is necessary to comply with federal 
law or attain or maintain any NAAQS. The section also establishes 
procedures and notice requirements for a county legislative body to 
establish or change the frequency of a vehicle emissions I/M program.
    b. An amendment in 2017 to UCA Section 41-6a-1642 to allow a county 
that imposes a local emissions compliance fee to use revenue generated 
from the fee to promote programs to maintain a NAAQS. Section 41-6a-
1642 was also amended to state that vehicles may not be denied 
registration based solely on the presence of a defeat device covered in 
the Volkswagen partial consent decrees or an EPA-approved vehicle 
emission modification.
    c. An amendment in 2019 regarding ``Notification of Programmatic 
Changes.'' This requires that county legislative bodies consult with 
the Director of the UDAQ before their public comment process for any 
amendments to their I/M regulations or ordinances. Consultation is to 
include a written notice describing the proposed changes to the I/M 
program.
    The revisions to Part A (General Requirements and Applicability) 
also included changes to section 3 (General Summary) that addressed 
minor wording clarifications to the subsections entitled ``Out-of-state 
exemption'' and ``Vehicle inspection report.''
    We have evaluated the Governor's November 5, 2019 submittal of the 
above revisions to the Utah SIP Section X Part A and are proposing 
approval.
5. Subsection X, Vehicle Inspection and Maintenance Program, Part F, 
Cache County
    Section X, Part F of the Utah SIP addresses requirements for the 
implementation of the motor vehicle I/M program in Cache County. 
Section X, Part F of the SIP contains three main components for the 
Cache County I/M program: (1) Language addressing applicability, a 
general description of the program, and the time frame for its 
implementation; (2) the Cache County Emission Inspection/Maintenance 
Program Ordinance 2018-15; and (3) the Bear River Health Department's 
(BRHD) Regulation 2013-04. We note that the Cache County Ordinance 
2018-15 contains language that delegates the implementation of the 
Cache County I/M program to the BRHD.
    a. Under the heading ``1. Applicability,'' the revisions to the 
Cache I/M program note that the Cache I/M program was approved by the 
EPA on October 9, 2015 (80 FR 54237), and that the I/M program has been 
fully implemented.
    b. Under the heading ``2. Description of Cache I/M programs,'' the 
revisions to the Cache I/M program include:
    (1) ``Subject Fleet'': The subject fleet for an I/M inspection was 
changed from 1969 and newer to 1996 and newer. This change reflects the 
County's revision to its I/M program to remove the Two Speed Idle (TSI) 
test for vehicles 1995 and older. Our proposed approval of this I/M 
program relaxation is discussed further below in section vii.
    (2) ``Test Frequency'': This section was also revised to reflect 
that model year 1996 and newer vehicles are subject to a biennial I/M 
test. This revised language also shows the removal of a required I/M 
test for 1995 and older vehicles.
    (3) ``Test Equipment'': This section was modified to remove the 
phrase ``Analyzer calibration specifications'' and replace it with 
``Certified testing equipment.''
    (4) ``Test Procedures'': This section was revised to remove the TSI 
test for 1995 and older vehicles and to remove the County's TSI test 
for 1996 to 2007 medium-duty vehicles and 2008 and newer heavy-duty 
vehicles. As noted above, we provide additional discussion on this I/M 
program relaxation in section vii below.
    c. Under the heading ``3. I/M SIP Implementation,'' the revisions 
to the Cache I/M program involve the new language described below. This 
section notes that the I/M program ordinance, regulations, policies, 
procedures, and activities specified in the I/M SIP revision shall be 
implemented by January 1, 2021.
    (1) The revisions to Cache County's Ordinance 2013-04 
(Implementation of a Vehicle Emissions and Maintenance Program in Cache 
County) involved:
    (a) Revisions to the table of contents that reflect the removal of 
the TSI test in 2021, and renumbering of subsequent subsections.
    (b) Revisions to section 1.0 (Definitions) to remove several 
definitions and to modify and add several definitions.
    (c) Revisions to section 2.0 (Purpose) to clarify that the 
ordinance complies with applicable federal requirements and with Cache 
County Code Chapter 10.20.
    (d) Revisions to section 3.0 (Authority and Jurisdiction of the 
Department) to revise subsections to indicate the authority is as per 
Cache County Code Chapter 10.20 and its subdivisions.
    (e) Revisions to section 4.0 (Powers and Duties) to remove unneeded 
references to Technical Bulletins and to include ``Certified Testing 
``Equipment'' in place of ``testing equipment.''
    (f) Revisions to section 5.0 (Scope) to remove the unneeded 
reference to Technical Bulletins.
    (g) Revisions to section 6.0 (General Provisions) updating the 
applicability to vehicles registered in Cache County or principally 
operated there; adding references to Cache County Code Chapter 10.20 
and its applicable subdivisions; updating the reference to UAC Section 
41-6a-1642(10); revising the list of vehicles that are exempted from I/
M testing; clarifying the required I/M testing station signs; and 
inserting a new ``Compliance Assurance List'' section 6.8 with its 
requirements.
    (h) Revisions to section 7.0 (Permit Requirements of the Vehicle 
Emissions I/M Program Station) removed unneeded language relevant to 
TSI testing and adding language that a wireless internet connection may 
be required.
    (i) Revisions to section 8.0 (Training and Certification of 
Inspectors) added ``Certified Testing Equipment'' where ``test 
equipment'' previously appeared. The revisions also removed unneeded 
language relevant to TSI testing and the unneeded requirement for a 
``hands on'' test. The revisions added language in new section 8.4.3 
that an emission inspection certificate would not be issued to an 
inspector applying in Cache County who has a revoked or suspended 
certificate in another county.

[[Page 11698]]

    (j) Revisions to section 9.0 (Inspection Procedure) remove most of 
the inspection procedures from this section and place them instead in 
the revised Appendix D ``Test Procedures.'' In addition, language 
relating to the TSI test was removed and clarifying language 
referencing a ``Certified Emissions Inspector'' and ``Certified Testing 
Equipment'' has been added. Other revisions were made regarding 
``Waivers,'' emissions related repairs, and language in the new section 
9.6 regarding the exploration of new emission inspection technologies 
that would be vetted with, and approved by, Cache County, the State, 
and the EPA.
    (k) Revisions to section 10.0 (Engine Switching) involve 
clarification of the term ``EPA policy'' by including the reference to 
specific EPA policies (i.e., the EPA's March 1991 engine switching Fact 
Sheet and its September 1997 Memorandum 1a) and language clarifying the 
requirements that a vehicle with an engine that was switched meet the 
emission inspection requirements of Section 6.0.
    (l) Revisions to section 1.0 (Specifications for Certified Testing 
Equipment) remove previously applicable requirements for calibration 
gases, gas calibration with leak checks, and warranty and maintenance 
requirements, as these provisions were only applicable to the TSI test.
    (m) Revisions to section 12.0 (Quality Assurance) update references 
to ``Certified Testing Equipment.''
    (n) Revisions to prior section 13.0 (Cutpoint Standards for Motor 
Vehicle Exhaust Gases) remove this section in its entirety, as it was 
only applicable to the TSI test.
    (o) Revisions to renumbered section 13.0 (Disciplinary Penalties 
and Right to Appeal) renumber subsections and replace the term 
``audit'' with ``inspection.''
    (p) Revisions to renumbered section 14.0 (Penalty) involved the 
renumbering of the prior subsections to a new subsection 14.6 that 
states the Department shall request that the Utah Division of Motor 
Vehicles (DMV) revoke the registration of any vehicle that is unable to 
meet the required emissions standards or has not complied with the 
required emissions testing requirements of UAC Section 41-1a-110(6).
    (q) Revisions to renumbered section 15.0 (Severability) only 
involve the renumbering of the section.
    (r) Revisions to renumbered section 16.0 (Effective Date) involve 
the renumbering of the section and change from the prior effective date 
of May 27, 2015 to January 1, 2021.
    (s) Revisions to Appendix A only remove the reference to the fee 
for a TSI test.
    (t) Revisions to Appendix B remove Appendix B in its entirety as it 
related to motor vehicle emissions cut-points applicable to the TSI 
test. As the TSI test was removed from the ordinance, this prior 
Appendix B is no longer relevant and was removed. The Appendix is now 
titled ``Reserved.''
    (u) Revisions to Appendix D (Test Procedures) involve the 
relocation of most of the On-Board Diagnostic (OBD) testing procedures 
to Appendix D that were previously located in section 9.0 (Inspection 
Procedure). Additional language, regarding the OBD test procedures, was 
included that clarifies, updates, and supplements the prior OBD test 
procedures language in the prior Appendix D. Terms were updated to 
refer to ``Certified Emissions Equipment'' and ``Certified Emissions 
Inspector.'' Provisions were added for a ``Compliance Assurance 
Inspection'' for a vehicle and a ``Referee Inspection'' at the County's 
I/M Technical Center for vehicles having difficulty with the OBD test, 
and also for when a vehicle owner believes the emission test done at an 
inspection station was not done correctly. The prior Appendix D test 
procedures for the TSI test were removed.
    (v) Revisions to Appendix E (Certified Testing Equipment Standards) 
involved the removal of ``Technical Specifications and Calibration 
Gas'' from the Appendix title. All provisions and requirements for the 
TSI test were removed. Only the necessary provisions and requirements 
for the OBD test were retained and updated.
    (w) Revisions to Appendix F (Waivers for Not Ready Vehicles) 
include clarifications to the provisions for the second and third 
tests, additional language regarding statements about the vehicle from 
the vehicle manufacturer's dealership repair station, and a new item 
number 6 addressing cost requirements for a waiver.
    (x) Revision to Appendix G (Engine Switching) removing Appendix G 
in its entirety. The revised, allowable engine switching provisions 
were incorporated into section 10.0 above (Engine Switching).
    We have evaluated the Governor's November 5, 2019 submittal of the 
above revisions to Utah SIP Section X Part F and are proposing 
approval.
    (2) The revisions to Cache County's Ordinance 2013-04 
(Implementation of a Vehicle Emissions and Maintenance Program in Cache 
County) for the removal of the TSI test in 2021.
    In December 2018, the BRHD proposed to the Cache County Council to 
amend the Cache County vehicle emissions and maintenance program. The 
BRHD proposal was to discontinue the TSI test for vehicles 1995 and 
older due to a diminishing fleet of older light duty gasoline vehicles 
participating in the program, combined with increasing cost of 
maintaining the TSI testing equipment. The emission reductions benefit 
from these older vehicles was minimal compared to the resources 
required to operate the TSI test, and removal of the TSI test would not 
interfere with attainment and maintenance of the 2006 PM2.5 
24-hour NAAQS.
    The Cache County Council passed the proposal to discontinue the TSI 
program with an effective date of January 1, 2021. This effective date 
is reflected as part of the revisions to Ordinance 2013-04 discussed 
above. The TSI testing program covers light duty gasoline vehicles that 
are older than model year 1995 and was a component of the I/M control 
strategy used in the EPA-approved Logan PM2.5 Nonattainment 
SIP (83 FR 59315; November 23, 2018).
    The UDAQ, EPA Region 8, and the BRHD coordinated regarding this 
Cache County I/M program relaxation to ensure that the proposed I/M 
program changes do not interfere with state and federal air quality 
regulations, as required under provisions of section 110(l) of the CAA. 
CAA section 110(l) allows revisions to a SIP to be approved so long as 
they do not interfere with any applicable requirement concerning 
attainment and RFP or any other applicable requirement of this chapter 
of the CAA. To evaluate the removal of the TSI test, the State prepared 
a CAA section 110(l) demonstration, as provided in Appendix A of the 
maintenance plan, and submitted that demonstration with the Governor's 
November 5, 2019 submittal.
    On January 13, 2020, the Governor of Utah submitted the Logan 
PM2.5 maintenance plan, which contained the State's CAA 
section 110(l) demonstration for the removal of the I/M Program TSI 
biennial testing procedure for Cache County in 2021. Section 9 and 
Appendix A of the Logan PM2.5 maintenance plan show there 
will be minimal changes to the overall on-road mobile source emissions 
inventory within the Logan PM2.5 area. As noted in Table 3 
below and detailed in Appendix A of the maintenance plan, overall 
mobile source emissions decrease from 2017 to 2021, through fleet 
turnover and Federal tailpipe standards. The state's demonstration 
considered on-road vehicle emissions

[[Page 11699]]

from 2021-2026, as 2026 is the dispersion-modeled midpoint of the 
maintenance demonstration, and the dispersion modeling for 2035, which 
is the last year of the maintenance plan. In addition, the CAA section 
110(l) demonstration considered whether there would be interference 
with other NAAQS being monitored in Cache County.
    The State concluded that the removal of the TSI test will not 
interfere with the ability of the Logan area to continue to attain the 
2006 24-hour PM2.5 NAAQS from 2017 through 2026 and in the 
last year of the maintenance plan, 2035. The State's analysis 
considered emissions credit assigned to the overall I/M program, 
including OBD and TSI test, within Cache County within the 2021-2026 
period, and compared it to the emissions credit without the TSI program 
(OBD only). The mobile source emission estimates were based on 
meteorological conditions that occurred during three PM2.5 
episodes: January 1-12, 2011; December 7-19, 2013; and February 1-17, 
2016. Inventory estimations were created at the county level 
representing an average January weekday. The emission estimates were 
based on the EPA-approved MOVES2014b (May 2017 version) emissions 
model.
    In addition, the demonstration considered PM2.5 ambient 
air quality monitoring data from the Smithfield, Cache County site and 
non-interference with the other five NAAQS. The State's full CAA 
section 110(l) demonstration is included in the Governor's November 1, 
2019 submittal and is also provided in the docket to this action. The 
EPA's full review of the January 13, 2020 Logan PM2.5 
maintenance plan and redesignation request submission is in section B, 
``What Requirements Must Be Followed for Redesignation to Attainment?'' 
below.
    EPA agrees with the State's CAA 110(l) demonstration regarding the 
removal of the I/M TSI for Cache County in 2021, in particular the 
conclusion that the removal will not have an adverse impact on the 
overall on-road mobile source inventory within the Logan 
PM2.5 area from 2017 to 2021 and through 2026. Further, the 
State's maintenance plan dispersion modeling for both 2026 and 2035 
continues to show maintenance of the 2006 PM2.5 24-hour 
NAAQS even with this I/M program revision. In addition, the State has 
documented that the removal of the TSI test in 2021 will not impact the 
other NAAQS.\8\
---------------------------------------------------------------------------

    \8\ January 13, 2020 Logan NAA PM2.5 Redesignation 
Request Submittal; Section IX.A.28 Maintenance Plan; Appendix A.
---------------------------------------------------------------------------

    Therefore, we are proposing to approve the removal of the TSI test 
component of the BRHD's Ordinance 2013-04 I/M program in 2021 for 
vehicles 1995 and older.

B. What requirements must be followed for redesignation to attainment?

    For a NAA to be redesignated to attainment, the following 
conditions in section 107(d)(3)(E) of the CAA must be met:
    1. We must determine that the area has attained the NAAQS;
    2. The applicable implementation plan for the area must be fully 
approved under section 110(k) of the Act;
    3. We 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 and applicable 
federal air pollutant control regulations and other permanent and 
enforceable reductions;
    4. We must fully approve a maintenance plan for the area as meeting 
the requirements of CAA section 175A; and,
    5. The State containing the area must meet all requirements 
applicable to the area under section 110 and part D of the CAA.
    EPA has provided guidance on redesignation in the ``General 
Preamble,'' \9\ and has provided further guidance on processing 
redesignation requests in the following documents: (1) The Calcagni 
Memorandum; (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.
---------------------------------------------------------------------------

    \9\ See ``State Implementation Plans; General Preamble for the 
Implementation of Title I of the Clean Air Act Amendments of 1990,'' 
57 FR 13498, April 16, 1992.
---------------------------------------------------------------------------

    On January 13, 2020, the Governor of Utah submitted revisions to 
the SIP for R307-110-10, a maintenance plan for the Logan area, and a 
request that the EPA redesignate the area to attainment for 
PM2.5. Additionally, on November 5, 2019, the State of Utah 
submitted revisions to R307-110-31 (Section X, Vehicle Inspection and 
Maintenance Program, Part A, General Requirements and Applicability), 
R307-110-36 (Section X, Vehicle Inspection and Maintenance Program, 
Part F, Cache County), and revisions to SIP Section X, Vehicle 
Inspection and Maintenance Program, Part A, General Requirements and 
Applicability and revisions to SIP Section X, Vehicle Inspection and 
Maintenance Program, Part F, Cache County. The prior section discusses 
Utah's revisions to R307-110-10, R307-110-31, R307-110-36, Section X, 
Vehicle Inspection and Maintenance Program, Part A, General 
Requirements and Applicability, and Section X, Vehicle Inspection and 
Maintenance Program, Part F, Cache County. The section below discusses 
how Utah's redesignation request and maintenance plan meet the 
requirements of the Act for redesignation of the Logan area to 
attainment for PM2.5.

C. Do the redesignation request and maintenance plan meet CAA 
requirements?

1. Attainment of the 2006 24-Hour PM2.5 NAAQS
    To redesignate an area from nonattainment to attainment, the CAA 
requires the EPA to determine that the area has attained the applicable 
NAAQS (CAA section 107(d)(3)(E)(i)). On October 19, 2018, the EPA 
finalized a determination that the Logan NAA had attained the 2006 24-
hour PM2.5 NAAQS, based on 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 188(b)(2) is provided in Table 1, below.

[[Page 11700]]

           Table 1--Logan NAA Design Values From 2018 Determination of Attainment Under 188(b)(2) \10\
----------------------------------------------------------------------------------------------------------------
                                                       98th percentile value ([micro]g/m\3\)
             Monitor                AQS site ID  ------------------------------------------------    2015-2017
                                                       2015            2016            2017        design value
----------------------------------------------------------------------------------------------------------------
Smithfield, UT..................       490050007            28.9            34.0            36.0              33
Franklin, ID....................       160410001            18.8            33.3        \a\ 38.3          \a\ 30
----------------------------------------------------------------------------------------------------------------
\a\ This value includes 1 in 3 monitoring frequency from January 1-August 9, 2017, and daily monitoring
  frequency from August 10-December 31, 2017.

    Whether an area has attainedthe 2006 24-hour PM2.5 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 [micro]g/m\3\. A state must demonstrate that an area has 
attained the 2006 24-hour PM2.5 NAAQS through submittal of 
ambient air quality data from an ambient air monitoring network 
representing maximum PM2.5 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 PM2.5 98th percentile mass concentrations is equal to 
or below the 2006 24-hour PM2.5 NAAQS (35 [micro]g/m\3\), 
pursuant to 40 CFR 50.13. In making this showing, three consecutive 
years of complete air quality data must be used.
---------------------------------------------------------------------------

    \10\ See 83 FR 52983, October 19, 2018.
---------------------------------------------------------------------------

    Between 2016 and 2019, Utah and Idaho operated at least one 
PM2.5 monitor in each state of the Logan NAA. In 2017, Idaho 
operated two PM2.5 monitors: Franklin, ID and Preston, ID. 
The Preston monitor did not begin operation until February 24, 2017, 
however, thus producing an incomplete first quarter for the monitoring 
year. Due to this incomplete quarter in 2017, the Preston monitor did 
not produce a valid design value for the 2017-2019 period. Despite 
this, EPA finds that it is appropriate to conclude that the area has 
indeed continued to attain the 2006 PM2.5 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, UT and Preston, ID monitors provided in Table 2, below, 
shows that the Smithfield site consistently monitors higher levels of 
PM2.5 than the Preston site, indicating that Smithfield's 
location is more suitable to demonstrate maximum PM2.5 
concentrations in the Cache Valley. 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 part of the redesignation request for the Logan NAA, UDAQ 
submitted quality-assured, complete and valid ambient air quality data 
from the Smithfield monitoring site which demonstrates that the area 
has attained the 2006 24-hour PM2.5 NAAQS.The EPA has 
reviewed the subsequent daily PM2.5 ambient air monitoring 
data in the Logan NAA, consistent with the requirements at 40 CFR part 
50, and recorded in the EPA's AQS quality assured, quality-controlled, 
and State certified data for the monitoring design value \11\ periods 
of 2016-2018 and 2017-2019. This air quality data demonstrates that the 
Logan NAA continues to attain the 2006 24-hour PM2.5 NAAQS. 
For the 2016-2018 3-year period, the Smithfield monitor produced a 
design value of 33 [micro]g/m\3\.\12\ The area's 24-hour 
PM2.5 design values for the 2017-2019 3-year period are 
provided in Table 2.
---------------------------------------------------------------------------

    \11\ As defined in 40 CFR part 50, appendix N, section (1)(c).
    \12\ See https://www.epa.gov/air-trends/air-quality-design-values#report.

                    Table 2--Logan NAA Current PM2.5 98th Percentiles and Design Values \13\
----------------------------------------------------------------------------------------------------------------
                                                       98th percentile value ([micro]g/m\3\)       Design value
             Monitor                Monitor AQS  ------------------------------------------------     (3-year
                                        No.            2017            2018            2019          average)
----------------------------------------------------------------------------------------------------------------
Smithfield......................       490050007            36.0            27.9            35.1              33
Preston.........................       160410002        \a\ 17.3            27.2            30.1          \b\ NA
----------------------------------------------------------------------------------------------------------------
\a\ The Preston monitor operated at a 1 in 3 monitoring frequency throughout 2017, and did not begin operation
  until February 24, 2017, making the first quarter incomplete for this monitor with less than 50% of data
  reported.
\b\ Due to the incomplete first quarter in 2017, this design value does not meet validity requirements per 40
  CFR part 50, appendix N, section 4.2(c)(i).

    As Table 2 indicates, the Logan area has continued to attain the 
2006 24-hour PM2.5 NAAQS since the EPA issued its 
determination of attainment under 188(b)(2) for the area based on the 
2015-2017 design values shown in Table 1 above. The 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 
PM2.5 NAAQS and demonstrates that the area continues to 
attain the standard. Further information on PM2.5 monitoring 
is presented in Subsections IX.A.28.b(1) of the Utah portion of the 
Logan maintenance plan. We have evaluated the ambient air quality data 
and have determined that the Logan 2006 24-hour PM2.5 NAAQS 
NAA continues to attain the standard based on the available monitoring 
data.
---------------------------------------------------------------------------

    \13\ The Preston monitor does not have a valid design value for 
the 2017-2019 three-year period because of an incomplete 2017 
quarter 1 which cannot be substituted with quarter 1 data at the 
same monitor in 2018 or 2019 per 40 CFR part 50, appendix N, section 
4.2(c)(i) because it has below 50% complete data for that quarter.
---------------------------------------------------------------------------

    A separate EPA redesignation rulemaking will be conducted for the 
Idaho portion of the Logan NAA.

[[Page 11701]]

2. State Implementation Plan Approval
    Section 107(d)(3)(E)(ii) 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 section 110(k).
    On February 25, 2016 (81 FR 9343), October 19, 2016 (81 FR 71988), 
October 2, 2019 (84 FR 52368), and February 26, 2020 (85 FR 10989) the 
EPA approved revisions to several area source rules and approved new 
rules for PM2.5 NAAs into the Utah SIP, including the Logan 
PM2.5 NAA.
    On September 9, 2015 (80 FR 54237), the EPA finalized approval of 
SIP revisions to Utah's SIP Section X, Vehicle Inspection and 
Maintenance Program, Part A, General Requirements and Applicability; 
Section X. Vehicle Inspection and Maintenance Program, Part F, Cache 
County; and Utah Rule R307-110-1, R307-110-31, and R307-110-36, which 
IBR the Utah SIP into the Utah Rules, IBRs Utah SIP Section X, Vehicle 
Inspection and Maintenance Program, Part A, General Requirements and 
Applicability, and IBRs Utah SIP Section X, Vehicle Inspection and 
Maintenance Program, Part F, Cache County, respectively. Additionally, 
the EPA is acting on revisions to R307-110-31, R307-110-36, Utah's SIP 
Section X, Vehicle Inspection and Maintenance Program, Part A, General 
Requirements and Applicability, and on Section X. Vehicle Inspection 
and Maintenance Program, Part F, Cache County in this action. Our 
evaluation of these revisions is found in Section II.A.2, 3, 4, and 5 
above.
    Additionally, we completed a clean data determination (CDD) for the 
Logan PM2.5 NAA on October 19, 2018 (83 FR 52983). With this 
final rule, the EPA suspended the obligation for Utah to make 
submissions to meet certain CAA requirements related to attainment of 
the NAAQS. These suspended CAA requirements are: (1) Attainment 
demonstration; (2) projected emissions inventory; (3) RACM/RACT; (4) 
RFP; (5) MVEB; (6) contingency measures; and (7) quantitative 
milestones.
    On November 23, 2018 (83 FR 59315), the EPA approved portions of 
the Logan PM2.5 SIP which were: The emissions inventory; 
modeled attainment demonstration; determination for Major Stationary 
Source RACT; determination for On-Road Mobile Sources RACM; 
determination for Cache County I/M Program as additional reasonable 
measures; determination for Off-Road Mobile Sources RACM; and the 2015 
MVEB.
    On July 25, 2019 (84 FR 35831), the EPA approved revisions to UAC 
R307-403 (Permits: New and Modified Sources in Nonattainment Areas and 
Maintenance Areas) into the SIP.
    We have evaluated the actions above and have determined that 
through these actions, the State of Utah has a fully approved Logan 
PM2.5 SIP under section 110(k).
3. Improvement in Air Quality Due to Permanent and Enforceable 
Measures.
    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.
    Utah has implemented multiple area source rules in the Logan NAA. 
On February 25, 2016 (81 FR 9343), October 19, 2016 (81 FR 71988), 
October 2, 2019 (84 FR 52368), and February 26, 2020 (85 FR 10989) the 
EPA approved revisions to several area source rules and approved new 
rules for PM2.5 NAAs into the Utah SIP, including the Logan 
PM2.5 NAA.
    On September 9, 2015 (80 FR 54237), the EPA finalized approval of 
SIP revisions to Utah's SIP Section X, Vehicle Inspection and 
Maintenance Program, Part A, General Requirements and Applicability; 
Section X. Vehicle Inspection and Maintenance Program, Part F, Cache 
County; and to Utah Rule R307-110-1, R307-110-31, and R307-110-36, 
which IBR the Utah SIP into the Utah Rules, IBRs Utah SIP Section X, 
Vehicle Inspection and Maintenance Program, Part A, General 
Requirements and Applicability, and IBRs Utah SIP Section X, Vehicle 
Inspection and Maintenance Program, Part F, Cache County, respectively. 
Additionally, the EPA is acting on revisions to R307-110-31; R307-110-
36; Utah's SIP Section X, Vehicle Inspection and Maintenance Program, 
Part A, General Requirements and Applicability; and on Section X. 
Vehicle Inspection and Maintenance Program, Part F, Cache County. Our 
evaluation of these revisions is found in Section II.A.2, 3, 4, and 5 
above.
    Additionally, within section IX.A.28.b.3. of the Logan 
PM2.5 maintenance plan, UDAQ provides an assessment of the 
ambient air quality data collected at the Logan PM2.5 
monitor from the year monitoring began (2000) to 2018 (the last year of 
valid data before the maintenance plan was submitted), which shows an 
observable decrease in the monitored PM2.5. UDAQ observed 
both the 98th percentile average of the 24-hour data in the Logan 
PM2.5 NAA as well as the annual arithmetic mean which 
assisted in understanding the trends. The Logan PM2.5 NAA 
was only designated nonattainment for the 2006 24-hour PM2.5 
NAAQS; however, it is useful information in showing the decrease in 
emissions. The cold-pool temperature inversions during the winter 
months, which drive and trap secondary PM2.5, vary in 
strength and duration from year to year, and the PM2.5 
concentrations measured during these periods reflect this variability 
more than they reflect the gradual changes in emissions of direct 
PM2.5 and the PM2.5 precursors. This variability 
is evident in UDAQ's assessment, but when a line is fit through the 24-
hour data, a trend is seen going downward and indicates improvement at 
1 [micro]g/m\3\ per year. This episodic variability is reduced when 
reviewing the annual mean values of PM2.5 concentrations 
from 2000-2018. This annual mean includes all the high values 
identified as the 98th percentiles, still the trend is downward. UDAQ 
fitted a line through the annual mean PM2.5 concentration 
data collected at the Logan PM2.5 NAA which revealed a 
decreasing trend and indicates an improvement of 5.6 [micro]g/m\3\ over 
this 18-year span.
    We have evaluated the various state and federal control measures, 
historical emissions inventories, and the emission trends of the 
PM2.5 98th percentiles and annual PM2.5 mean 
concentrations presented by UDAQ from 2000 to 2018, and have determined 
that the improvement in air quality in the Logan NAA has resulted from 
emission reductions that are permanent and enforceable.
4. Fully Approved Maintenance Plan Under Section 175A of the Act
    Section 107(d)(3)(E) of the Act requires that for a NAA to be 
redesignated to attainment, we must fully approve a maintenance plan 
meeting the requirements of section 175A of the Act. 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

[[Page 11702]]

the NAAQS.\14\ The EPA's interpretations of the CAA section 175A 
maintenance plan requirements are generally provided in the General 
Preamble and the Calcagni Memorandum referenced above. The Calcagni 
Memorandum outlines five core elements necessary to ensure maintenance 
of the relevant NAAQS in an area seeking redesignation from 
nonattainment to attainment. Those elements, as well as guidelines for 
subsequent maintenance plan revisions, are explained in detail below.
---------------------------------------------------------------------------

    \14\ CAA sections 175A(b) and (d).
---------------------------------------------------------------------------

a. Attainment Inventory
    PM2.5 maintenance plans should include an attainment 
emission inventory to identify the level of emissions in the area that 
is sufficient to maintain the NAAQS. An emissions inventory was 
developed and submitted with the Logan PM2.5 maintenance 
plan NAA on January 13, 2020. This submittal contains a base year of 
2017, interim-year projected inventory for 2026, and a projected 
maintenance inventory of 2035. The emissions in the inventories include 
sources of PM2.5 and PM2.5 precursor emissions 
within a regional area called a modeling domain. UDAQ modeled two 
different domain sizes; 4 km coarse and 1.33 km fine.\15\ The 4 km 
coarse domain covered the entire State of Utah, a significant portion 
of Eastern Nevada (including Las Vegas), and smaller portions of Idaho, 
Wyoming, Colorado, and Arizona. Since the coarse domain was so large, 
the 1.33 km fine domain or a ``core area'' within this domain was 
identified wherein a higher degree of spatial resolution was used in 
the model. Within this core area (which includes Weber, Davis, Salt 
Lake, Utah, Box Elder, Tooele, Cache, and Franklin, ID Counties), SIP-
specific inventories were prepared to include seasonal adjustments and 
forecasting to represent each of the projection years. In the bordering 
region, the 2014 National Emissions Inventory (NEI) was used in the 
analysis. Four general categories of sources were included in these 
inventories: point sources; area sources; on-road mobile sources; and 
non-road mobile sources.
---------------------------------------------------------------------------

    \15\ See January 13, 2020 State of Utah submittal for Logan 
PM2.5 Maintenance Plan; Figure IX.A.28.4, CAMx 
Photochemical Modeling Domain in Two-Way Nested Configuration.
---------------------------------------------------------------------------

    For each of these source categories, the pollutants inventoried 
were PM2.5, sulfur dioxide (SO2), NOX, 
VOC, and ammonia (NH3). More detailed descriptions of the 
2017 base-year inventory and the 2026 and 2035 projection inventories 
can be found in section IX.A.28.c., Logan Maintenance Plan, subsection 
(2) Attainment Inventory, and within the State of Utah's technical 
support document (TSD). Utah's submittal contains detailed emission 
inventory information prepared in accordance with EPA emission 
inventory guidance.\16\ Summaries of emission figures from the 2017 
base year and the projected inventories are in Table 3 below.
---------------------------------------------------------------------------

    \16\ ``Emissions Inventory Guidance for Implementation of Ozone 
and Particulate Matter National Ambient Air Quality Standards 
(NAAQS) and Regional Haze Regulations,'' EPA-454/B-17-002 (May 
2017), available at https://www.epa.gov/sites/production/files/2017-07/documents/ei_guidance_may_2017_final_rev.pdf .

                                Table 3--Logan NAA; Actual Emissions From 2017 and Emission Projections for 2026 and 2035
                                                                  [Tons per day (tpd)]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                   PM2.5         PM2.5       PM2.5
                    Year                              Source category           filterable    condensible    total      NOX      VOC      NH3      SO2
--------------------------------------------------------------------------------------------------------------------------------------------------------
2017 Baseline...............................  Area Sources...................          0.56          0.05       0.6      0.92      3.8    13.48     0.03
                                              Non-Road.......................  ............  ............       0.1      0.79     2.19        0        0
                                              Point Sources..................             0             0         0         0        0        0        0
                                              Mobile Sources.................  ............  ............      0.23      3.76     2.46      0.1     0.02
                                                                              --------------------------------------------------------------------------
                                                 2017 Total..................  ............  ............      0.93      5.47     8.45    13.58     0.05
2026........................................  Area Sources...................          0.60          0.04      0.64       0.7     3.88    13.27     0.03
                                              Non-Road.......................  ............  ............      0.06      0.59     1.27        0        0
                                              Point Sources..................             0             0         0         0        0        0        0
                                              Mobile Sources.................  ............  ............      0.13      1.52     1.39     0.09     0.01
                                                                              --------------------------------------------------------------------------
                                                 2026 Total..................  ............  ............      0.83      2.81     6.54    13.36     0.04
2035........................................  Area Sources...................          0.63          0.04      0.67      0.71     4.29    13.11     0.03
                                              Non-Road.......................  ............  ............      0.05      0.57     1.04        0        0
                                              Point Sources..................             0             0         0         0        0        0        0
                                              Mobile Sources.................  ............  ............      0.19      1.76     1.91      0.1     0.01
                                                                              --------------------------------------------------------------------------
                                                 2035 Total..................  ............  ............      0.91      3.04     7.24    13.21     0.04
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Based on our review, we have determined that Utah prepared an 
adequate attainment inventory for the Logan PM2.5 NAA.
b. Maintenance Demonstration
    The Calcagni Memorandum states that where modeling was relied on to 
demonstrate maintenance, the plan must contain a summary of the air 
quality concentrations expected to result from the application of the 
control strategies. Also, the plan should identify and describe the 
dispersion model or other air quality model used to project ambient 
concentrations. The maintenance demonstration for the Logan area used a 
regional photochemical model.
    Before the development of the Logan PM2.5 maintenance 
plan, UDAQ conducted a technical analysis to support the development of 
the Serious SIP for the Salt Lake City, UT PM2.5 NAA. The 
analysis included preparation of emissions inventories and 
meteorological data, and the evaluation and application of a regional 
photochemical model. Part of this process included selection of the 
episode that most accurately replicates the photochemical formation of 
ambient PM2.5 during a persistent cold air pool episode in 
the airshed. For the Logan maintenance plan, UDAQ used the same episode 
that was used for the Serious SIP modeling.
    The Comprehensive Air Quality Model with Extensions (CAMx) version 
6.30 for air quality modeling was used for the Logan maintenance plan, 
with enhancements including snow chemistry and topographical and 
surface albedo refinements. The emissions processing model that UDAQ 
used in conjunction with CAMx was the

[[Page 11703]]

Sparse Matrix Operator Kernel Emissions Modeling System (SMOKE) version 
3.6.5. Meteorological inputs were derived using the Weather Research 
and Forecasting (WRF) Advanced Research WRF (WRF-ARW) model to prepare 
meteorological datasets for UDAQ to use with the photochemical model. 
UDAQ found that WRF-ARW was reasonably able to replicate the vertical 
temperature structure of the boundary layer (i.e., the winter 
temperature inversion in the NAA), but that WRF-ARW had difficulty 
reproducing the inversion when the inversion was shallow and strong 
(e.g., an 8-degree temperature increase over 100 vertical meters). UDAQ 
provides additional information on these models in their TSD.\17\
---------------------------------------------------------------------------

    \17\ January 13, 2020 Logan PM2.5 Redesignation 
Request/Maintenance Plan TSD, Section 4.e Meteorological Modeling.
---------------------------------------------------------------------------

    Part of the modeling exercise that UDAQ completed for the Logan 
maintenance plan was to test whether the model could successfully 
replicate the PM2.5 mass and composition that were observed 
during prior episode(s) of elevated PM2.5 concentrations. 
After consulting EPA guidance,\18\ UDAQ selected three episodes: (1) 
January 1-10, 2011; (2) December 7-19, 2013; and (3) February 1-16, 
2016. UDAQ examined the PM2.5 model performance for these 
three episodes and concluded that the CAMx performed the best when 
using the January 2011 WRF-ARW output. UDAQ further confirmed this 
determination by using a linear regression analysis showing that 
modeled and measured PM2.5 at the Logan monitoring station 
was strongly correlated during the January 2011 episode (R\2\ = 0.72) 
compared to the other episodes (R\2\ = 0.18 for the December 2013 
episode, and R\2\ = 0.39 for the February 2016 episode). A 
comprehensive discussion of the meteorological model performance for 
all three of these episodes can be found in the TSD submitted by UDAQ.
---------------------------------------------------------------------------

    \18\ Guidance on the Use of Models and Other Analyses for 
Demonstrating Attainment of Air Quality Goals for Ozone, 
PM2.5, and Regional Haze, EPA454/B-07-002 (Apr. 2007).
---------------------------------------------------------------------------

    UDAQ compared the 24-hour modeled and observed PM2.5 
during the January 1-10, 2011 episode at the Logan monitoring station, 
and the results showed that overall, the model captured the temporal 
variation in PM2.5 well. This temporal variation included a 
gradual increase in PM2.5 concentration and its transition 
back to low levels. However, UDAQ discovered that despite the generally 
good representation of the temporal behavior of PM2.5, the 
concentrations were, generally, lower in the model on January 4-9, 
2011. This was partly related to the meteorological model performance 
on these days where temperature was overestimated by 5 to 15 degrees 
Celsius, and thick, low-level clouds were simulated on January 5, 2011, 
while clouds were not observed for this day.\19\ Due to this low-level 
cloud simulation produced from the model, an increasingly deep sub-
cloud mixing layer in the model was observed compared to reality, which 
led to an underprediction in modeled PM2.5 concentrations. A 
more detailed analysis of this episode can be found in the Utah TSD.
---------------------------------------------------------------------------

    \19\ PM2.5 State Implementation Plan Meteorological 
Modeling; Prepared by Department of Atmospheric Sciences, University 
of Utah for UDAQ.
---------------------------------------------------------------------------

    Overall, UDAQ concluded that the model performance of replicating 
the buildup and clear out of PM2.5 in the Logan NAA was 
good, and thus, the model could be used for air quality planning 
purposes.
    With acceptable model performance, the model can be utilized to 
make future-year attainment projections. For each future year, an 
attainment projection is made by calculating a concentration termed the 
Future Design Value (FDV). This calculation is made for each monitor 
included in the analysis, then compared to the NAAQS (35 [micro]g/
m\3\). An FDV below the NAAQS at every monitor in the NAA would 
demonstrate attainment for the area in that specific future year. A 
maintenance plan must demonstrate continued attainment of the NAAQS for 
a span of ten years. Since this ten-year span is measured from when the 
EPA takes final action on the maintenance plan, the exact ten-year date 
cannot be known before the plan is submitted. To be conservative, UDAQ 
projected an attainment date of 2035, which is fifteen years after Utah 
submitted the Logan maintenance plan. Additionally, UDAQ modeled a 
``spot-check'' assessment of 2026.
    In making future-year projections, the output from the CAMx model 
is not considered the final answer; rather, the model is used in a 
relative sense. In doing this, a comparison is made using the predicted 
concentrations for both the year in question and a pre-selected base-
year, which is 2017. This comparison results in a Relative Response 
Factor (RRF). An RRF greater than one indicates that according to the 
model, the predicted PM2.5 level is greater in the future 
year than in the 2017 base year, which typically is a result of 
increased emissions in the future year associated with projected 
population growth. (Additional discussion of the RRF can be found in 
the maintenance plan and the TSD submitted by UDAQ.) The FDV is 
calculated by multiplying the BDV by the RRF. FDV's are compared to the 
NAAQs in order to determine whether attainment is predicted at each 
monitoring location. Table 4 below provides FDV results for the 
Smithfield monitor and projection year and shows that no FDV exceeds 
the NAAQS. Therefore, continued attainment is demonstrated in the Logan 
NAA.

 Table 4--Baseline Design Value, Relative Response Factors, and Future Design Values for All Monitors and Future
                                              Projection Years \20\
----------------------------------------------------------------------------------------------------------------
             Monitor               2016-2018 BDV     2026 RRF        2026 FDV        2035 RRF        2035 FDV
----------------------------------------------------------------------------------------------------------------
Smithfield......................            32.6            0.86            28.0            0.87            28.2
----------------------------------------------------------------------------------------------------------------

    According to the Calcagni memorandum, any assumptions concerning 
emission rates must reflect permanent, enforceable measures. A state 
cannot take credit in the maintenance demonstration for reductions 
unless there are regulations in place requiring those reductions, or 
the reductions are otherwise shown to be permanent. States are expected 
to maintain implemented control strategies despite redesignation to 
attainment, unless measures that achieve equivalent reductions are 
approved into the SIP. Emission reductions from source shutdowns can be 
considered permanent and enforceable to the extent that those shutdowns 
have been

[[Page 11704]]

reflected in the SIP and all applicable permits have been modified 
accordingly.
---------------------------------------------------------------------------

    \20\ These values include additional emissions added to the CMPO 
MVEB from the safety margin. The safety margin is discussed further 
in Section D below. Units of Design Values are [micro]g/m\3\, while 
RRF's are dimensionless.
---------------------------------------------------------------------------

    As part of the Moderate PM2.5 SIPs, 24 area source rules 
were either introduced or augmented by UDAQ to control PM2.5 
and PM2.5 precursors. On February 25, 2016 (81 FR 9343), 
October 19, 2016 (81 FR 71988), October 2, 2019 (84 FR 52368), and 
February 26, 2020 (85 FR 10989), the EPA acted on area source rules for 
the Logan PM2.5 NAA. There are no changes to these area 
source rules with this action.
    With respect to the part of Franklin County, ID that is included in 
the Logan NAA, UDAQ provided general information on Idaho's Moderate 
PM2.5 SIP and what EPA's Region 10 office had acted on for 
control measures. On January 4, 2017 (82 FR 729) and on March 25, 2014 
(79 FR 16203), the EPA approved the residential woodstove curtailment 
program/change-out program and the road sanding agreements, 
respectively, as voluntary measures. Additional information on Idaho's 
SIP will be available when EPA's Region 10 office acts on Idaho's 
portion of the Logan maintenance plan.
    Based on the information described above and in our TSD, the EPA 
proposes to find that Utah has adequately demonstrated that the Logan 
area will maintain the 2006 24-hour PM2.5 NAAQS for the next 
fifteen years.
c. 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. Accordingly, the maintenance plan should contain provisions for 
continued operation of air quality monitors. As described in the 
maintenance plan, Utah will continue to maintain and operate a 
PM2.5 ambient monitoring network within the Logan 
PM2.5 area in accordance with 40 CFR part 58 and the Utah 
SIP. We approve these sites annually, and any future change would 
require discussion and approval from the EPA. In its January 13, 2020 
submittal, Utah commits to continue to maintain an ambient monitoring 
network for PM2.5 in the Logan area, in accordance with 40 
CFR part 58 and the Utah SIP.
d. Verification of Continued Attainment
    Utah's maintenance plan submittal for the Logan area must indicate 
how the State will track the progress of the maintenance plan. This is 
necessary because the emissions projections made for the maintenance 
demonstrations depend on assumptions of point and area source growth. 
In Section IX.A.28.c.(7), Utah commits to track and document measured 
mobile source parameters (e.g., vehicle miles traveled, congestion, 
fleet mix) and changes in new and modified stationary source permits. 
If these and the resulting emissions change significantly over time, 
the State will perform appropriate studies to determine: (1) Whether 
additional and/or re-sited monitors are necessary; and (2) whether 
mobile and stationary source emission projections are on target.
e. Contingency Plan
    Section 175A(d) of the Act 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. For 
the maintenance plan to be approved under section 175A, a state is not 
required to have fully adopted contingency measures that will take 
effect without further action by the state. 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 in the Part D 
nonattainment plan for the area before redesignation. The state should 
also identify the specific indicators, or triggers, that will be used 
to determine when the contingency plan will be implemented.
    As stated in Section IX.A.28.c.(8) of the Logan maintenance plan, 
triggering the contingency plan does not automatically require a 
revision to the SIP, nor does it necessarily mean the area will be 
reclassified to nonattainment. Instead, Utah will normally have an 
appropriate timeframe to correct the potential violation by 
implementing one or more adopted contingency measures. If violations 
continue to occur, additional contingency measures will be implemented 
until the violations are corrected.
    Upon monitoring a potential violation of the 2006 24-hour 
PM2.5 NAAQS, including exceedances flagged as exceptional 
events but not concurred with by the EPA, the State will identify a 
means of corrective action within six months after a potential 
violation. Utah will require implementation of the corrective action no 
later than one year after the violation is confirmed, and any 
contingency measures adopted and implemented will become part of the 
next revised maintenance plan submitted for EPA approval.
    The Logan maintenance plan list of contingency measures includes: 
(1) Reinstate TSI test portion of the Cache County I/M Program; (2) 
Measures to address emissions from residential wood combustion (i.e., 
emissions from fireplaces under the existing R307-302 rule), including 
re-evaluating the thresholds at which red or yellow burn days are 
triggered; (3) Measures to address fugitive dust from area sources; and 
(4) Additional measures to address other PM2.5 sources 
identified in the emissions inventory, such as on-road vehicles, and 
non-road vehicles and engines.
    Based on the above, we propose to find that the contingency 
measures provided in the Logan PM2.5 maintenance plan are 
sufficient and meet the requirements of section 175A(d) of the CAA.
f. Subsequent Maintenance Plan Revisions
    In accordance with section 175A(b) of the Act, Utah is required to 
submit a revision to the maintenance plan eight years after the 
redesignation of the Logan area to attainment for PM2.5. 
This revision is to provide for maintenance of the NAAQS for an 
additional ten years following the first ten-year period. In the Logan 
maintenance plan, Utah committed to submit a revised maintenance plan 
eight years after the approval of the redesignation request and 
maintenance plan.
5. Meeting Applicable Requirements of Section 110 and Part D of the Act
    In order for an area to be redesignated to attainment, section 
107(d)(3)(E) provides that it must have met all applicable requirements 
of section 110 and part D of the Act. We interpret this to mean that, 
for a redesignation request to be approved, Utah must have met all 
requirements that applied to the subject area as of the time of 
submitting a complete redesignation request. In our evaluation of a 
redesignation request, we don't need to consider other requirements of 
the CAA that became due after the date of the submission of a complete 
redesignation request.
a. Section 110 Requirements
    Section 110(a)(2) contains general requirements for attainment 
plans. For purposes of redesignation, the Utah SIP was reviewed to 
ensure that all applicable requirements under the amended Act were 
satisfied. On September 21, 2010, the State submitted an Infrastructure 
SIP to the EPA demonstrating compliance with the

[[Page 11705]]

requirements of section 110 that are applicable to the 2006 24-hour 
PM2.5 NAAQS. We approved this submittal on November 25, 2013 
(78 FR 63883), for all section 110 requirements applicable to 
redesignation.
b. Part D Requirements
    Before a PM2.5 NAA may be redesignated to attainment, a 
state must have fulfilled the applicable requirements of part D. 
Subpart 1 of part D establishes general requirements applicable to all 
NAAs, while subpart 4 of part D establishes specific requirements 
applicable to PM10/PM2.5 NAAs. The 
PM2.5 Requirements Rule provides that the applicable 
requirements of CAA section 172 are 172(c)(3) (emissions inventory), 
172(c)(5) (NSR permitting program), 172(c)(7) (the section 110(a)(2) 
air quality monitoring requirements), and 172(c)(9) (contingency 
measures). Also, as explained in the Calcagni Memorandum, we interpret 
the requirements of section 172(c)(2) (RFP) and 172(c)(6) (other 
measures) as being irrelevant to a redesignation request because they 
only have meaning for an area that is not attaining the standard. 
Finally, the State has not sought to exercise the options that would 
trigger sections 172(c)(8) (equivalent techniques). Thus, these 
provisions are also not relevant to this redesignation request.
    The requirements of section 172(c) and 189(a) regarding attainment 
of the 2006 24-hour PM2.5 NAAQS, and the requirements of 
section 172(c) regarding RFP, imposition of RACM, the adoption of 
contingency measures, and the submission of an emission inventory, have 
been satisfied through our February 25, 2016 (81 FR 9343), October 19, 
2016 (81 FR 71988), October 19, 2018 (83 FR 52983), November 23, 2018 
(83 FR 59315), October 2, 2019 (84 FR 52368), and February 26, 2020 (85 
FR 10989) actions approving portions of the Moderate PM2.5 
Logan SIP and CDD. The CDD suspended Utah's obligation to make a SIP 
submission, or supplement, for attainment-related requirements 
including an attainment demonstration, RACM/RACT, RFP, contingency 
measures, and milestone reports.
    We approved the requirements of the part D NNSR permit program for 
Utah on July 25, 2019 (84 FR 35831). Once the Logan area is 
redesignated to attainment, the prevention of significant deterioration 
(PSD) requirements of part C of the Act will apply. We must ensure that 
the State has made any needed modifications to its PSD regulations so 
that Utah's PSD regulations will apply in the Logan area after 
redesignation. Utah's PSD regulations, R307-405 Permits: Major Sources 
in Attainment or Unclassified Areas (PSD), which we approved as meeting 
all applicable federal requirements on July 15, 2011 (76 FR 41712) and 
January 29, 2016 (81 FR 4957), apply to any area designated 
unclassifiable or attainment, and thus will become fully effective in 
the Logan area upon redesignation of the areas to attainment.

D. Have the transportation conformity requirements been met?

(i) Requirements for Transportation Conformity and Motor Vehicle 
Emissions Budgets (MVEB)
    Transportation conformity is required by section 176(c) of the CAA. 
The 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. To effectuate its 
purpose, the EPA's conformity rule requires a demonstration that 
emissions from a Metropolitan Planning Organization's (MPO) Regional 
Transportation Plan (RTP) and Transportation Improvement Program (TIP), 
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). An MVEB is defined as 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. 
Further information concerning the EPA's interpretations regarding 
MVEBs can be found in the preamble to the EPA's November 24, 1993, 
transportation conformity rule.\21\
---------------------------------------------------------------------------

    \21\ 58 FR 62193-62196.
---------------------------------------------------------------------------

    The EPA notes that a PM2.5 maintenance plan should 
identify MVEBs for direct PM2.5, NOX and all 
other PM2.5 precursors whose on-road mobile source emissions 
are determined to significantly contribute to PM2.5 levels 
in the area. We note that for the Logan PM2.5 maintenance 
plan SIP revision, the UDAQ also identified VOCs as a precursor to the 
formation of PM2.5 in the Logan PM2.5 area. For 
direct PM2.5 SIP MVEBs, the MVEB should include direct 
PM2.5 motor vehicle emissions from tailpipes, brake wear, 
and tire wear. In addition, a state must also consider whether re-
entrained road dust is a significant contributor and should be included 
in the direct PM2.5 MVEB.\22\ With respect to this 
requirement, the EPA reviewed information, data, and an analysis from 
the UDAQ that sufficiently documented that re-entrained road dust 
emissions were negligible and meet the criteria of 40 CFR 93.102(b)(3) 
for not needing to be included in the direct PM2.5 MVEB. The 
EPA concurred with the State's analysis in an email dated July 20, 2011 
to UDAQ.\23\
---------------------------------------------------------------------------

    \22\ 40 CFR 93.102(b) and 93.122(f); see also conformity rule 
preamble at 69 FR 40004, 40031-40036 (July 1, 2004).
    \23\ ``PM2.5 Re-entrained Road Dust--Utah Request for 
Deletion from PM2.5 Motor Vehicle Emissions Budget 
(MVEB): EPA Concurrence'' dated July 20, 2011 (included in docket 
for this action).
---------------------------------------------------------------------------

(ii) MVEBs Identified in the Logan PM2.5 Maintenance Plan 
SIP
    Utah's Logan PM2.5 maintenance plan SIP revision was 
submitted to meet the requirements of CAA section 175A and relevant EPA 
guidance.\24\ The State's maintenance plan specified the maximum mobile 
source emissions of PM2.5, NOX and VOC allowed in 
the final maintenance year, which is 2035. These mobile source 
emissions were initially identified by the State as the maintenance 
plan's MVEBs. However, through additional sensitivity dispersion 
modeling, the State was able to demonstrate that for 2035, additional 
mobile sources emissions could be included such that the Logan area 
could continue to demonstrate maintenance. These additional direct 
PM2.5, NOX, and VOC mobile source emissions were 
then identified as a ``safety margin'' \25\ and were then added to the 
initial MVEBs to arrive at the final MVEBs. This process of identifying 
an additional ``safety margin'' was correctly followed by the UDAQ and 
is allowed by 40 CFR 93.124(a). The derivation of the MVEBs, with a 
``safety margin,'' is described in Section 4 ``Mobile Source Budget for 
Purposes of Conformity'' of the maintenance plan and Section ``3.e. On-
road Mobile Baseline and Projection Inventories, ii. On-Road MVEB 
Derivation'' of the TSD. As presented in Table IX.A.28.9 of the 
maintenance plan, the final 2035 MVEBs were 0.2 tpd direct 
PM2.5, 2.02 tpd NOX, and 2.18 tpd VOCs.
---------------------------------------------------------------------------

    \24\ 57 FR 13498, April 16, 1992.
    \25\ 40 CFR 93.101.
---------------------------------------------------------------------------

    We note that 40 CFR 93.118(b)(2)(i) indicates that for maintenance 
plans that do not identify MVEBs for any other year than the last year 
of the

[[Page 11706]]

maintenance plan, the demonstration of consistency with the MVEBs by 
the applicable MPO must be accompanied by a qualitative finding that 
there are no factors that would cause or contribute to a new violation 
or exacerbate an existing violation in the years before the last year 
of the maintenance plan.
(iii) MVEBs Trading, for Purposes of Demonstrating Transportation 
Conformity, in the Logan PM2.5 Maintenance Area
    The EPA's transportation conformity rule allows for trading between 
the direct PM2.5 and NOX and VOC precursor MVEBs 
where the SIP establishes an appropriate mechanism for such trades.\26\ 
The basis for the trading mechanism is the maintenance plan's 
dispersion modeling demonstration for 2035, which established the 
relative contribution of the NOX and VOC precursor 
pollutants.
---------------------------------------------------------------------------

    \26\ 40 CFR 93.124(b).
---------------------------------------------------------------------------

    As discussed in Section 4(a)(ii) (``Trading Ratios for 
Transportation Conformity'') of the maintenance plan, the State 
established a MVEB trading mechanism to allow for future increases in 
on-road mobile sources direct PM2.5 emissions to be offset 
by future decreases in NOX precursor emissions from on-road 
mobile sources. This ratio was developed from data from the air quality 
maintenance plan's dispersion modeling. Section 4(a)(ii) of the 
maintenance plan and Section 6 of the maintenance plan's TSD provide 
the following modeling-derived trading ratio: Future increases in on-
road mobile sources direct PM2.5 emissions may be offset 
with future decreases in NOX emissions from on-road mobile 
sources at a NOX to PM2.5 ratio of 3.4 to 1.
    The maintenance plan also notes that this trading mechanism will 
only be used by the Cache MPO for transportation conformity 
determination analyses for years after 2035. The maintenance plan 
further notes that to ensure that the trading mechanism does not impact 
the ability to meet the NOX budget, the NOX 
emission reductions available to supplement the direct PM2.5 
MVEB will only be those remaining after the 2035 NOX MVEB 
has been met. The maintenance plan further articulates that clear 
documentation of the calculations used in the MVEB trading must be 
included in the conformity determination analysis as prepared by the 
Cache MPO.
(iv) EPA's Evaluation of Mobile Source Revisions
    The EPA has evaluated the Logan PM2.5 maintenance plan's 
emission inventories and maintenance demonstration modeling as 
described in the sections above. Based on our evaluation, we have 
determined that the direct PM2.5, NOX, and VOC 
MVEBs are appropriately derived from the maintenance plan and are 
acceptable. We have also evaluated the description and derivation of 
the MVEB NOX trading mechanism and the supporting data from 
the maintenance plan's maintenance demonstration modeling information 
and TSD and find it acceptable. Therefore, we are proposing to approve 
the Logan UT-ID PM2.5 maintenance plan's 2035 MVEBs of 
direct PM2.5 of 0.2 tpd, NOX of 2.02 tpd, and VOC 
of 2.18 tpd. In addition, we are proposing to approve the 
NOX to direct PM2.5 MVEB trading mechanism as 
described above and documented in Section 4(a)(ii) of the maintenance 
plan.

E. Did Utah follow the proper procedures for adopting this action?

    Section 110(k) of the CAA addresses our actions on submissions of 
revisions to a SIP. The Act also requires states to observe certain 
procedural requirements in developing implementation plans and plan 
revisions for submission. Section 110(a)(2) of the Act provides that 
each implementation plan submitted by a state must be adopted after 
reasonable notice and public hearing. Section 110(l) of the Act 
similarly provides that each revision to an implementation plan 
submitted by a state under the Act must be adopted by the state after 
reasonable notice and public hearing.
    We also must determine whether a submittal is complete and 
therefore warrants further review and action.\27\ Our completeness 
criteria for SIP submittals are at 40 CFR part 51, appendix V. We 
attempt to make completeness determinations within 60 days of receiving 
a submission. However, a submittal is deemed complete by operation of 
law under section 110(k)(1)(B) of the Act if a completeness 
determination is not made within six months after receipt of the 
submission.
---------------------------------------------------------------------------

    \27\ Section 110(k)(1) of the Act and 57 FR 13565, April 16, 
1992.
---------------------------------------------------------------------------

    On June 5, 2019, the UAQB proposed amendments to Utah SIP Section 
X, Vehicle Inspection and Maintenance Program, Parts A and F, R307-110-
31, and R307-110-36. The comment period was held from July 1, 2019, to 
July 31, 2019. No comments were received, and no public hearing was 
requested. On September 4, 2019, the UAQB adopted revisions to R307-
110-31, R307-110-36, and to Utah SIP Section X, Vehicle Inspection and 
Maintenance Program, Parts A and F. These revisions became effective on 
September 5, 2019, and UDAQ submitted these revisions to the EPA on 
November 5, 2019.
    On September 4, 2019, the UAQB proposed for public comment the 
Logan maintenance plan and redesignation request and revisions to R307-
110-10. The public comment period was held from October 1, 2019, to 
October 31, 2019. UDAQ received comments from industry and citizens; 
and no public hearing was requested. UDAQ provided the comments and 
their responses within the submittal. The comments did not prompt UDAQ 
to substantively revise any documents. UDAQ made a few minor revisions 
to the plan once the data and modeling were verified. On December 4, 
2019, the UAQB adopted R307-110-10 and the Logan maintenance plan/
redesignation request, and they became effective on December 5, 2019. 
UDAQ submitted these revisions and the TSD to the EPA on January 13, 
2020.

III. Proposed Action

    We are proposing to approve the Governor of Utah's submittal of 
January 13, 2020, which contains revisions to R307-110-10 and the Logan 
PM2.5 maintenance plan and redesignation request. We are 
also proposing to approve the Governor of Utah's submittal of November 
5, 2019, which contains revisions to R307-110-31, R307-110-36, Utah SIP 
Section X.A., and Utah SIP Section X.F. We are proposing to approve the 
maintenance plan's 2035 MVEBs. In addition, we are also proposing to 
approve the NOX-to-direct-PM2.5 MVEB trading 
mechanism. We are proposing approval of these submissions because UDAQ 
has adequately addressed all requirements of the Act for the SIP 
revisions and the redesignation to attainment applicable to the Logan 
2006 24-hour PM2.5 NAA. We are using 2017-2019 ambient air 
quality data from Logan NAA as the basis for our decision. We have 
evaluated the ambient air quality data and have determined that the 
Logan 2006 24-hour PM2.5 NAAQS NAA continues to attain the 
standard based on the available monitoring data. A separate EPA 
redesignation rulemaking will be conducted for the Idaho portion of the 
Logan NAA. Upon the effective date of a subsequent final action, the 
designation status of the Utah portion of the Logan area under 40 CFR 
part 81 will be revised to attainment.

[[Page 11707]]

IV. Incorporation by Reference

    In this document, the EPA is proposing to include regulatory text 
in an EPA final rule that includes incorporation by reference. In 
accordance with requirements of 1 CFR 51.5, the EPA is proposing to 
incorporate by reference revisions to R307-110-10; R307-110-31; R307-
110-36; Utah SIP Section X.A.; Utah SIP Section X.F.; maintenance plan 
for the Utah portion of the Logan PM2.5 NAA; and the 
redesignation request for the Logan PM2.5 NAA to attainment. 
The EPA has made, and will continue to make, these materials generally 
available through www.regulations.gov and at the EPA Region 8 Office 
(please contact the person identified in the FOR FURTHER INFORMATION 
CONTACT section of this preamble for more information).

V. Statutory and Executive Order Reviews

    Under the CAA, the Administrator is required to approve a SIP 
submission that complies with the provisions of the Act and applicable 
federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in 
reviewing SIP submissions, the EPA's role is to approve state choices, 
provided that they meet the criteria of the CAA. Accordingly, this 
action merely proposes to approve state law as meeting federal 
requirements and does not impose additional requirements beyond those 
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. Accordingly, the proposed 
rule does not have tribal implications and will not impose substantial 
direct costs on tribal governments or preempt tribal law as specified 
by Executive Order 13175 (65 FR 67249, November 9, 2000).

List of Subjects

40 CFR Part 52

    Environmental protection, Air pollution control, Carbon monoxide, 
Greenhouse gases, 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, 
and Wilderness areas.

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

    Dated: February 17, 2021.
Debra Thomas,
Acting Regional Administrator, EPA Region 8.
[FR Doc. 2021-03819 Filed 2-25-21; 8:45 am]
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