[Federal Register Volume 85, Number 216 (Friday, November 6, 2020)]
[Proposed Rules]
[Pages 71023-71046]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-24444]


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

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R08-OAR-2020-0098; FRL-10016-53-Region 8]


Approval and Promulgation of Implementation Plans; State of Utah; 
Salt Lake City and Provo, Utah PM2.5 Redesignations to Attainment and 
Utah State Implementation Plan Revisions

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule.

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

SUMMARY: The Environmental Protection Agency (EPA) is proposing the 
redesignation of the Salt Lake City, Utah and Provo, Utah nonattainment 
areas (NAAs) to attainment for the 2006 24-hour fine particulate matter 
with an aerodynamic diameter less than or equal to a nominal 2.5 
microns (PM2.5) National Ambient Air Quality Standard 
(NAAQS), and also acting on multiple related State Implementation Plan 
(SIP) submissions. We are proposing to approve SIP revisions submitted 
by the State of Utah on January 19, 2017; April 19, 2018; February 4 
and 15, 2019; and January 13, May 21, and July 21, 2020. These SIP 
submissions include revisions to Utah Administrative Code (UAC) 
Sections R307-110, R307-200, and R307-300 Series; revisions to Utah SIP 
Sections X.B and E; revisions to Utah SIP Sections IX.H.11, 12, and 13; 
best available control measures/best available control technologies 
(BACM/BACT) PM2.5 determinations for Salt Lake City and 
Provo; maintenance plans for the Salt Lake City and Provo areas for 
PM2.5; and the request for redesignation under the 2006 24-
hour PM2.5 standard. Additionally, the EPA is proposing to 
approve, through parallel processing, a request to remove startup and 
shutdown emission limits for Kennecott's Power Plant in the Utah SIP 
and the accompanying R307-110-17 revisions (draft dated October 9, 
2020). The EPA is taking this action pursuant to the Clean Air Act (CAA 
or the Act).

DATES: Written comments must be received on or before December 7, 2020.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R08-
OAR-2020-0098, 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

[[Page 71024]]

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, [email protected].

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 (40 CFR 50.2(b)). 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.
---------------------------------------------------------------------------

    \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.
---------------------------------------------------------------------------

    Under section 109 of the Act, the EPA has promulgated NAAQS for 
certain pollutants, including PM2.5 (40 CFR 50.2(b)). 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.\2\ 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.
---------------------------------------------------------------------------

    \2\ 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.
---------------------------------------------------------------------------

    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 November 13, 2009 (74 FR 
58688), the EPA designated three NAAs in Utah for the 2006 24-hour 
PM2.5 NAAQS of 35 [micro]g/m\3\. These are the Salt Lake 
City; Provo; and Logan, Utah-Idaho NAAs.
    The EPA originally issued a rule in 2007 \3\ 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. 
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.
---------------------------------------------------------------------------

    \3\ 72 FR 20586 (Apr. 25, 2007).
---------------------------------------------------------------------------

    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 and subpart 4 of CAA title I, part D.\4\ 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.
---------------------------------------------------------------------------

    \4\ Nat. Res. Def. Council v. EPA, 706 F.3d 428, 437 (D.C. Cir. 
2013) (NRDC).
---------------------------------------------------------------------------

    On June 2, 2014 (79 FR 31566), the EPA finalized 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. 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 
of December 31, 2015.
    When an area is designated as a Moderate NAA under subpart 1 and 
subpart 4, the CAA requires the State to submit the following Moderate 
area SIP elements:
    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,

[[Page 71025]]

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. These submissions are referred to as 
``quantitative milestone reports.'' (CAA section 189(c)).
    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 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 (``PM2.5 Requirements 
Rule''), which partially 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 that apply to areas 
designated nonattainment for any PM2.5 NAAQS, 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). The statutory attainment planning requirements of 
subparts 1 and 4 were established to ensure that the following goals of 
the CAA are met: (i) That states implement measures that provide for 
attainment of the PM2.5 NAAQS as expeditiously as 
practicable; and (ii) that states adopt emissions reduction strategies 
that will be the most effective at reducing PM2.5 levels in 
NAAs.
    If an area is reclassified from Moderate to Serious, the area will 
then be subject to Serious PM2.5 CAA requirements. Serious 
area PM2.5 requirements are the same as those listed above 
for Moderate areas, except that BACM and BACT are required instead of 
RACM and RACT, the NNSR permit threshold drops to 70 tons, and the 
relevant attainment date is the Serious area attainment date (CAA 
section 188(c)(2). Serious area PM2.5 plans must also 
satisfy the Moderate PM2.5 requirements discussed above, and 
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).

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

    After the November 13, 2009 designation of nonattainment for the 
2006 24-hour PM2.5 NAAQS, Utah developed draft 
PM2.5 attainment plans intended to meet the requirements of 
subpart 1. The EPA submitted written comments dated November 1, 2012, 
to UDAQ on the draft PM2.5 SIP, technical support document 
(TSD), area source rules, and point source rules in Section IX, Part 
H.\5\ Utah submitted revised 2006 24-hour PM2.5 attainment 
plans for the Salt Lake City and Provo NAAs on December 14, 2012.
---------------------------------------------------------------------------

    \5\ An ``area source'' is ``any small residential, governmental, 
institutional, commercial, or industrial fuel combustion operation; 
onsite solid waste disposal facility; motor vehicle], aircraft 
vessel or other transportation facilit[y] or other miscellaneous 
source identified'' through specified inventory techniques. 40 CFR 
51.100(l). A ``point source'' is any stationary source emitting 
above certain thresholds. 40 CFR 51.100(k).
---------------------------------------------------------------------------

    After the court's 2013 decision, Utah amended its attainment plans 
to address the requirements of subpart 4. On December 2, 2013, and 
October 30, 2014, the EPA provided comments on Utah's revised draft 
2006 24-hour PM2.5 SIPs, including the TSD and emissions 
limits in Section IX, Part H. On December 16, 2014, UDAQ withdrew all 
prior Salt Lake City and Provo 2006 24-hour PM2.5 Moderate 
SIP attainment plan submissions and submitted a subpart 1 and subpart 4 
Salt Lake City and Provo 2006 24-hour PM2.5 Moderate SIP. 
Additionally, the State of Utah submitted various revisions to the UAC 
Title R307 (Environmental Quality) area source rules in multiple 
submissions: February 2, 2012; May 9, 2013; June 8, 2013; February 18, 
2014; April 17, 2014; May 20, 2014; July 10, 2014; and August 6, 2014. 
These area source rules were either new or revised to meet RACM/RACT 
for the Salt Lake City and Provo 2006 24-hour PM2.5 SIPs. 
The EPA acted on these submittals, along with the area source rule 
revisions in the December 16, 2014 submission, 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).
    On January 19, 2017, the State of Utah submitted revisions to their 
Part H.11, 12, and 13 emission limits section of the Utah 2006 24-hour 
PM2.5 SIP and revises R307-110-17. R307-110-17 incorporates 
by reference (IBR) Section IX, Control Measures for Area and Point 
Sources, Part H, Emission Limits; which formally incorporates the Salt 
Lake City and Provo 2006 24-hour PM2.5 Part H.11, 12, and 13 
emission limits into Utah's state regulations. This was undertaken by 
UDAQ to correlate any overlapping limits between the 2006 24-hour 
PM2.5 Part H.11, 12, and 13, to the coarse particulate 
matter (PM10) Part H.1, 2, 3, and 4.
    On May 10, 2017 (82 FR 21711), the EPA published a final rule 
reclassifying the Salt Lake City and Provo areas to ``Serious'' 
nonattainment status, based on the EPA's determination that the areas 
could not practicably attain the 2006 24-hour PM2.5 
standards by the December 31, 2015 attainment date. This 
reclassification became effective on June 9, 2017. The reclassification 
was based on the EPA's evaluation of ambient air quality data from the 
2013-2015 period, indicating that it was not practicable for some of 
the monitoring sites in the Salt Lake City and Provo areas to show 
PM2.5 design values at or below the level of the 2006 24-
hour PM2.5 NAAQS by December 31, 2015.
    On March 23, 2018, the State of Utah submitted quantitative 
milestone reports for the Salt Lake City and Provo 2006 24-hour 
PM2.5 NAAs, meeting its due date of no later than 90 days 
after the December 31, 2017 milestone date. On October 24, 2018, the 
EPA determined that the 2017 quantitative milestone reports for the 
Salt Lake City and Provo 2006 24-hour PM2.5 NAAs were 
adequate.\6\
---------------------------------------------------------------------------

    \6\ The state's quantitative milestone reports and the adequacy 
determination letter from the EPA Administrator to the Governor of 
Utah are in the docket for this action.
---------------------------------------------------------------------------

    After the Serious reclassification, UDAQ revised certain area 
source rules in UAC Section R307-200 and R307-300 Series and submitted 
these revisions on April 19, 2018, May 21, 2020, and July 21, 2020. On 
February 4,

[[Page 71026]]

2019, the State of Utah submitted the BACM/BACT analysis for the Provo 
Serious 2006 24-hour PM2.5 NAA, which is based on the 
emission limits submitted on January 19, 2017 for only Part H.13. On 
February 15, 2019, Utah submitted the Serious 2006 24-hour 
PM2.5 SIP for the Salt Lake City NAA, which included 
revisions to Utah SIP Part H.11 and 12, and the accompanying BACM/BACT 
analysis. The February 4, 2019 and February 15, 2019 submissions 
included BACM/BACT analyses for on-road, off-road, and area source 
rules; some of these area source rules were revised and others were 
deemed BACM/BACT without revising. Our detailed discussion on the 
intricacies of these submissions can be found in Section II.B below of 
this document.
    Applying the Clean Data Policy,\7\ on April 10, 2019 (84 FR 14267) 
and September 27, 2019 (84 FR 51055), the EPA finalized determinations 
that the obligation to submit any remaining attainment-related SIP 
revisions arising from classification of the Provo and Salt Lake City 
areas, respectively, as Moderate NAAs and their subsequent 
reclassification as Serious NAAs for the 2006 24-hour PM2.5 
NAAQS does not apply for so long as the area continues to attain the 
2006 24-hour PM2.5 NAAQS.\8\ The attainment-related SIP 
revisions that were suspended include the requirements for the State to 
submit: An attainment demonstration (Moderate and Serious), provisions 
demonstrating timely implementation of RACM/RACT (Moderate), an RFP 
plan (Moderate and Serious), quantitative milestones and quantitative 
milestone reports (Moderate and Serious), and contingency measures 
(Moderate and Serious). The only remaining SIP elements for EPA action 
include baseline emission inventories, NNSR, and BACM/BACT. Our review 
of these remaining elements is in Section II.B below of this document 
and in our TSD found in the docket.
---------------------------------------------------------------------------

    \7\ The EPA codified the Clean Data Policy in the 
PM2.5 SIP Requirements Rule for the implementation of 
current and future PM2.5 NAAQS. See 81 FR at 58161; 40 
CFR 51.1015(a).
    \8\ 40 CFR 51.1015(a) and (b).
---------------------------------------------------------------------------

    On October 9, 2020, the State of Utah submitted draft revisions to 
Kennecott's Power Plant startup/shutdown emission limits in Subsection 
IX.H.12.i.i.C. in Utah's SIP and revisions to R307-110-17, for the EPA 
to act on as a parallel process. UDAQ's BACM/BACT analysis submitted on 
February 15, 2019 for this source did not support these limits; 
therefore, UDAQ proposed with the October 9, 2020 draft revision to 
remove these limits. The parallel process is generally described in 
more detail in Section I.E below.

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.
    Our September 4, 1992 guidance entitled ``Procedures for Processing 
Requests to Redesignate Areas to Attainment'' (referred to in this 
action as the Calcagni Memorandum) outlines how to assess 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, maintenance plans for the Salt Lake City (Utah 
SIP Section IX.A.36) and Provo (Utah SIP Section IX.A.27) areas, and a 
request that the EPA redesignate the areas 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 Salt Lake City and Provo 2006 24-hour 
PM2.5 Maintenance Plans (located within the Utah SIP at 
Sections IX.A.36 and 27, respectively) into Utah's state regulations. 
In Section II.C below, we discuss our review of UDAQs maintenance plans 
and redesignation requests for the Salt Lake City and Provo 2006 24-
hour PM2.5 NAAs.

D. SIP Submissions Supporting the Redesignation Request

    Vehicle I/M programs help improve air quality by identifying cars 
and trucks with high emissions and that may need repairs. Owners or 
operators of vehicles with high emissions are notified to make any 
repairs so that emissions are within legal limits. On July 17, 1997 (62 
FR 38213), and September 14, 2005 (70 FR 54267), the EPA finalized 
approval of revisions to Utah's SIP Section X, Vehicle Inspection and 
Maintenance Program for Part B, Davis County, and Part E, Weber County, 
respectively. In these actions the EPA also approved into the SIP 
revisions to Utah's regulations at R307-110-32 and R307-110-35. These 
rules IBR the Utah SIP into state regulations: Rule R307-110-32 IBRs 
Utah SIP Section X, Vehicle Inspection and Maintenance Program, Part B, 
Davis County; and Rule R307-110-35 IBRs Utah SIP Section X, Vehicle 
Inspection and Maintenance Program, Part E, Weber County.\9\
---------------------------------------------------------------------------

    \9\ Since promulgating R307-110-32, Utah has renumbered its SIP. 
On February 14, 2006 (71 FR 7679), the EPA renumbered the Weber 
County I/M Program to R307-110-32. R307-110-35 was last approved on 
September 14, 2005.70 FR 54267.
---------------------------------------------------------------------------

E. What is parallel processing?

    Parallel processing refers to a process that utilizes concurrent 
state and Federal proposed rulemaking actions. Generally, the state 
submits a copy of the proposed regulation or other revisions to the EPA 
before conducting its public hearing and completing its public comment 
process under state law. The EPA reviews this proposed state action and 
prepares a notice of proposed rulemaking under Federal Law. In some 
cases, the EPA's notice of proposed rulemaking is published in the 
Federal Register during the same time frame that the state is holding 
its public hearing and conducting its public comment process. The state 
and the EPA then provide for concurrent public comment periods on both 
the state action and Federal action. If, after completing its public 
comment process and after the EPA's public comment process has run, the 
state changes its final submittal from the proposed submittal, the EPA 
evaluates those changes and decides on whether to publish another 
notice of proposed rulemaking in light of those changes or to proceed 
to taking the final action on its proposed action and describe the 
state's changes in its final rulemaking action. Any final rulemaking 
action by the EPA will occur only after the final submittal has been 
adopted by the state and formally provided to the EPA.
    In this case, however, the EPA's and Utah's processes have not been 
perfectly concurrent. The State submitted the draft SIP revisions on 
October 9, 2020, with a public comment period starting October 1 and 
going through November 3, 2020, with a public hearing held online at 
10am on November 3, 2020.

[[Page 71027]]

Utah requested that the EPA parallel process these proposed revisions 
while the State finishes the comment period and public hearing, so as 
not to delay the 2006 24-hour PM2.5 redesignation of the 
Salt Lake City NAA. The State's intention is to submit its final SIP 
revisions in early January 2021. After Utah submits these formal SIP 
revisions, the EPA will evaluate the submittal. If the State changes 
the formal submittal from the proposed submittal, the EPA will evaluate 
those changes for significance. If the EPA finds any such changes to be 
significant, then the Agency intends to determine whether to re-propose 
the actions based on the revised submission or to proceed to take final 
action on the submittal as changed by the State. Although the EPA was 
unable to have a concurrent public comment process with the State, 
Utah's request for parallel processing allows the EPA to begin to take 
action on the State's proposed submittal in advance of a formal and 
final submission.

II. The EPA's Evaluation

A. Utah's SIP Revisions

    When certain sections of the Utah SIP are amended by the Utah Air 
Quality Board (UAQB), those sections must be incorporated into the Utah 
Air Quality Rules. Utah incorporates SIP sections within 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. For the Salt Lake City and Provo 2006 24-hour 
PM2.5 proposed action, we are acting on R307-110-10, which 
IBRs Section IX, Control Measures for Area and Point Sources, Part A, 
Fine Particulate Matter, and thus incorporates the Salt Lake City and 
Provo 2006 24-hour PM2.5 maintenance plans into state 
regulations (located within the Utah SIP at Sections IX.A.36 and 27, 
respectively). We are also proposing to approve into the SIP R307-110-
17, which IBRs Section IX, Control Measures for Area and Point Sources, 
Part H, Emission Limits, and thus incorporates all the emission limits 
in Utah SIP Section IX.H.11, 12, and 13, into state regulations. The 
state's R307-110-32 and R307-110-35 IBR Section X, Vehicle Inspection 
and Maintenance Program, Part B, Davis County, and Section X, Vehicle 
Inspection and Maintenance Program, Part E, Weber County, respectively. 
These two rules incorporate the I/M Programs of Davis and Weber 
Counties into the state regulations.
    Utah Code 41-6a-1642 gives authority to each county in the State to 
design and manage a vehicle I/M program when necessary to attain or 
maintain any NAAQS. Section X of the Utah SIP incorporates these county 
programs. Section X, Part A summarizes I/M requirements that are common 
among all I/M programs, while Section X, Parts B through F contain the 
requirements for each county's unique I/M program. Below we discuss the 
revisions to Utah SIP Section X, Parts B and E, and to the related 
Rules R307-110-10, R307-110-32, and R307-110-35, along with our 
evaluation. We discuss the revisions done to Utah SIP Section X, Parts 
B and E, in greater detail within the TSD. Utah Rule R307-110-17 will 
be going through the parallel process based on the informal October 9, 
2020 UDAQ submission revising Utah SIP Section IX.H.12.i.i.C, which 
requires a revision to R307-110-17 to incorporate the revisions into 
the Utah SIP. In Section I.E above, we discuss the process of this type 
of action.
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 by 
itself include any SIP measures.
2. R307-110-17
    Section R307-110-17 incorporates the amendments to Utah SIP Section 
IX, Control Measures for Area and Point Sources, Part H, Emission 
Limits 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 2, 2020, and 
does not by itself include any SIP control measures; however, this 
revision is being acted on as a parallel process due to revisions to 
Utah SIP Section IX.H.12.i.i.C. In Section I.E above, we discuss the 
process of this type of action.
3. R307-110-32
    Section R307-110-32 incorporates the amendments to Utah SIP Section 
X, Vehicle Inspection and Maintenance Program, Part B, Davis 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 March 4, 2020 and does not by itself include 
any control measures.
4. R307-110-35
    Section R307-110-35 incorporates the amendments to Utah SIP Section 
X, Vehicle Inspection and Maintenance Program, Part E, Weber County 
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 March 4, 2020 and does not by itself 
include any control measures.
5. SIP Section X, Vehicle Inspection and Maintenance Program, Part B, 
Davis County
    The Davis County motor vehicle I/M program was last approved by the 
EPA on July 17, 1997 (62 FR 38213). The County has since made numerous 
improvements, updates and revisions to the I/M program ordinance, while 
removing unnecessary and obsolete provisions and sections. The version 
of the Davis County I/M program that we are now proposing to approve 
supersedes and replaces the July 17, 1997 version. The Davis County I/M 
Ordinance was enacted and adopted by the Davis County Commission on 
October 1, 2019 and became effective October 18, 2019, and the 
Ordinance was adopted into the SIP by the UAQB on March 4, 2020, at 
Section X, part B. This is the version that was submitted to the EPA 
and is discussed below.
    Section X, Part B of the SIP contains two main components for the 
Davis County I/M program: (a) Language addressing applicability, a 
general description of the Davis County I/M program, and the time frame 
for implementation of the I/M program; and (b) the Davis County 
Emission Inspection/Maintenance Program, as enacted in Davis County 
Ordinance 10.12.
    a. State Language Addressing the Davis County I/M Program:
    Under the heading ``1. Applicability'' is a description of the 2019 
revised Davis County I/M program, and a history of the Salt Lake and 
Davis county federal ozone NAAQS attainment status and the development 
of the Davis County I/M program. The section also notes that the Davis 
County I/M program was included as a control measure in the 2006 24-
hour PM2.5 NAAQS.
    Under ``2. Summary of Davis County I/M Program,'' the state 
describes various aspects of the revised Davis County I/M program: 
Network Type, Test Convenience, Subject Fleet, Test Frequency, Station 
Inspector Audits, Waivers, Test Equipment, and Test Procedures.
    Under the heading ``3. I/M SIP Implementation,'' the State notes 
that the Davis I/M program will continue to apply until a maintenance 
plan without an I/M program is approved by the EPA in accordance with 
Section 175 of the CAA.

[[Page 71028]]

    b. Revisions to Davis County's ``Davis County Vehicle Emissions 
Inspection/Maintenance Program Ordinance'' amend the Ordinance's 
sections 10.12.020 Definitions, 10.12.030 Purpose, 10.12.040 
Jurisdiction of the Division, 10.12.050 Powers and Duties, 10.12.060 
Scope, 10.12.070 General Provisions, 10.12.080 Standards and 
Specifications for Emissions Inspection Analyzers and Span Gases for 
Equipment, 10.12.090 Requirements of the Vehicle Emissions Inspection/
Maintenance Program Stations, 10.12.100 Requirements of the Certified 
Emissions Testers and/or Repair Technicians, 10.12.110 Official 
Inspection Procedures, 10.12.130 Emissions Standards for Motor 
Vehicles, 10.12.140 Certificates of Compliance and Waivers, 10.12.150 
Engine Switching, 10.12.160 Right to Appeal, 10.12.170 Recall, 
10.12.180 Penalty, 10.12.200 Quality Assurance, 10.12.210 Severability, 
10.12.240 Fee Schedule, 10.12.250 Emissions Standards, 10.12.260 Waiver 
Cut Points, 10.12.270 Passing Versus Waiver Cut Point Comparison, 
10.12.280 Penalty Schedule, and 10.12.290 Conflicts.
    In addition, the State has submitted revisions to: Appendix A, 
involving the provisions and requirements for emission inspection 
analyzer specifications; Appendix B, involving the Two Speed Idle (TSI) 
emissions inspection procedures; Appendix C, involving the OBDII (On-
Board Diagnostics Generation II) inspection procedures; Appendix D, 
involving the Davis County Diesel I/M Program, which the EPA notes that 
we are not proposing to act on: and Appendix E, involving compressed 
natural gas vehicle emissions inspection procedures.
    We have evaluated the Governor's May 21, 2020 submittal of the 
above revisions to the Utah SIP Section X Part B and the revised Davis 
County Ordinance, with respect to the applicable provisions and 
requirements in 40 CFR part 51, subpart S ``Inspection/Maintenance 
Program Requirements,'' and are proposing approval. Additional 
information and the EPA's more detailed evaluation of the above 
materials are found in the accompanying TSD. The entire Davis County 
Ordinance is in the Docket for this action.
6. SIP Section X, Vehicle Inspection and Maintenance Program, Part E, 
Weber County
    The Weber County motor vehicle I/M program was last approved by the 
EPA on September 14, 2005 (70 FR 54267). The County has since made 
numerous improvements, updates and revisions to the I/M program 
ordinance, while removing unnecessary and obsolete provisions and 
sections. The version of the Weber County I/M program that we are now 
proposing to approve supersedes and replaces the prior September 14, 
2005 EPA-approved version. The Weber County I/M Regulation was enacted 
and adopted by the Weber-Morgan Board of Health on September 23, 2019, 
and the Weber-Morgan Health Department (WMHD) implements the I/M 
program on behalf of Weber County. The Regulation was adopted into the 
SIP by the UAQB on March 4, 2020. This is the version that was 
submitted to the EPA and is discussed below.
    Section X, Part E of the Utah SIP addresses the provisions and 
requirements for the implementation of the motor vehicle I/M program in 
Weber County, Utah. Section X, Part E of the SIP contains two main 
components for the Weber County I/M program: (a) Language for Section X 
Part E that addresses applicability, a general description of the Weber 
County I/M program, and the time frame for implementation of the I/M 
program; and (b) the WMHD Motor Vehicle I/M Program Regulation.
    a. State Language Addressing the Weber County I/M Program:
    Under the heading ``1. Applicability'' is a description of the 2019 
revised Weber County I/M program, a history of the Weber county federal 
ozone NAAQS attainment status and the development of the Weber County 
I/M program. The section also notes that the Weber County I/M program 
was included as a control measure in the 2006 24-hour PM2.5 
NAAQS.
    Under the heading ``2. Summary of Weber County I/M Program,'' the 
State describes certain aspects of the revised Weber County I/M program 
involving: Network Type, Test Convenience, Subject Fleet, Test 
Frequency, Station Inspector Audits, Waivers, Test Equipment, and Test 
Procedures.
    Under the heading ``3. I/M SIP Implementation'' the State notes 
that the Weber I/M program will continue to apply until a maintenance 
plan without an I/M program is approved by the EPA in accordance with 
Section 175 of the CAA.
    b. Revisions to Weber County's ``Weber-Morgan Health Department 
Regulation for Motor Vehicle Inspection and Maintenance Program'' amend 
the regulation's: Section 1 Title and Definitions, Section 2 Purpose, 
Section 4 Powers and Duties, Section 6 General Provisions, Section 7 
Standards and Specifications for Analyzers and Calibration Gases, 
Section 8 Permit Requirements of the Vehicle Emissions Station, Section 
9 Inspection Procedure, Section 10 Certificate of Waiver, Section 12 
Certified Emissions Inspection and Repair Technician/Certified 
Emissions Inspection Only Technician Permit, Section 14 Certificate of 
Compliance, Certificate of Compliance Numbers, and Certificate of 
Waiver, Section 15 Adjudicative Proceedings, and Section 18 Effective 
Date.
    In addition, the State has submitted revisions to Appendix A-
Analyzer Specifications, Appendix B- Fee Schedule, Appendix C-Motor 
Vehicle Emissions Inspection and Maintenance Program, Appendix D-
Penalty Schedule, Appendix E-OBD IM Test Procedures, Appendix F 
entitled ``Diesel Fueled Vehicle Test Procedure,'' which the EPA notes 
that we are not taking any action on this Appendix, and a new Appendix 
G entitled ``Adjustment Procedures.''
    We have evaluated the Governor's May 21, 2020 submittal of the 
above revisions to the Utah SIP Section X Part E and the revised Weber 
County Regulation, with respect to the applicable provisions and 
requirements in 40 CFR part 51, subpart S ``Inspection/Maintenance 
Program Requirements,'' and are proposing approval. Additional 
information and the EPA's more detailed evaluation of the above 
materials are found in the accompanying TSD. The entire Weber County 
Regulation is in the Docket for this action.

B. PM2.5 SIP Plan

    On August 24, 2016 the EPA finalized the PM2.5 SIP 
Requirements Rule,\10\ which established regulatory requirements 
related to the statutory SIP requirements for areas designated 
nonattainment for the PM2.5 standards.
---------------------------------------------------------------------------

    \10\ 81 FR 58010.
---------------------------------------------------------------------------

    As discussed in the PM2.5 SIP Requirements Rule, 
sections 189(a), (c), and (e) of the CAA require that Moderate area 
attainment plans contain the following: (i) An approved permit program 
for construction of new and modified major stationary sources (CAA 
section 189(a)(1)(A)); (ii) a demonstration that the plan provides for 
attainment by no later than the applicable Moderate area attainment 
date or a demonstration that attainment by that date is impracticable 
(CAA section 189(a)(1)(B)); (iii) provisions for the implementation of 
RACM/RACT no later than 4 years after designation (CAA section 
189(a)(1)(C)); (iv) quantitative milestones that will be used to 
evaluate compliance with the requirements to demonstrate RFP (CAA 
section 189(c));

[[Page 71029]]

and (v) evaluation and regulation of PM2.5 precursors (in 
general to meet RACM/RACT and other attainment planning requirements, 
and also as specifically provided for major stationary sources under 
CAA section 189(e)).
    Sections 189(b) and (c) of the CAA include the following 
requirements for Serious area attainment plan submissions: (i) An 
attainment demonstration (CAA section 189(b)(1)(A)); (ii) provisions 
for the implementation of BACM/BACT no later than 4 years after 
reclassification of the area to Serious (CAA section 189(b)(1)(B)); 
(iii) quantitative milestones that will be used to evaluate compliance 
with the requirement to demonstrate RFP (CAA section 189(c)); and (iv) 
regulation of PM2.5 precursors (in general to meet 
attainment and control strategy requirements, and as specifically 
required for major stationary sources by CAA section 189(e)).
    Other subpart 1 requirements for attainment plans not otherwise 
superseded under subpart 4 also apply to Moderate and Serious areas for 
the 2006 24-hour PM2.5 NAAQS, including (i) a description of 
the expected annual incremental reductions in emission that will 
demonstrate RFP (CAA section 172(c)(2)); (ii) emissions inventories 
(CAA section 172(c)(3)); (iii) other control measures (besides RACM/
RACT for Moderate areas and BACM/BACT for Serious areas) needed for 
attainment (CAA section 172(c)(6)); and (iv) contingency measures (CAA 
section 172(c)(9)).
    In connection with the Moderate area SIP for the 2006 24-hour 
PM2.5 NAAQS, the EPA has previously acted on a number of 
Utah SIP revisions related to area sources. In particular, on February 
2, 2012; May 9, 2013; June 8, 2013; February 18, 2014; April 17, 2014; 
May 20, 2014; July 10, 2014; and August 6, 2014, UDAQ submitted either 
new area source rules or revisions to rules found in UAC Title R307 
(Environmental Quality). We acted on these rule revisions 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).
    On December 16, 2014, UDAQ submitted additional Moderate 2006 24-
hour PM2.5 SIP revisions for the Provo and Salt Lake City 
NAAs. CAA section 110(k)(1)(B) requires the EPA to determine whether a 
SIP submission is complete within 60 days of receipt. This section also 
provides that any plan that the EPA has not affirmatively determined to 
be complete or incomplete will become complete by operation of law six 
months after the date of submission. The EPA's SIP completeness 
criteria are in 40 CFR part 51, appendix V. The 2014 2006 24-hour 
PM2.5 plan became complete by operation of law on June 22, 
2014. Additionally, UDAQ submitted revisions to the Utah SIP Part H.11, 
12 and 13 of the Moderate 2006 24-hour PM2.5 SIPs for the 
Provo and Salt Lake City NAAs on January 19, 2017, which became 
complete by operation of law on July 20, 2017.
    On May 10, 2017 (82 FR 21711), the EPA determined that the Provo 
and Salt Lake City NAAs failed to attain the 2006 24-hour 
PM2.5 NAAQS by the Moderate attainment date of December 31, 
2015. With this determination, the Provo and Salt Lake City NAAs were 
reclassified as a ``Serious'' area for the 2006 24-hour 
PM2.5 NAAQS, with a new attainment date of December 31, 
2019. This reclassification triggered an obligation for Utah to submit 
a new, Serious area attainment plan including the CAA elements listed 
above. Additionally, CAA section 189(b)(1) requires that ``in 
addition'' to the attainment plan requirements specific to Serious 
areas, states must also meet all Moderate area attainment plan 
requirements. The EPA interprets the statutory language of CAA section 
189(b)(1) to require states with areas that are reclassified to Serious 
to meet Moderate area attainment plan requirements, including all areas 
that the EPA reclassifies through rulemaking under its discretionary 
authority, even if that occurs before the area has met all of its 
Moderate area attainment plan requirements. The following section 
describes the EPA's final actions in this rule regarding Serious area 
attainment plan requirements in greater detail.
    On April 10, 2019 (84 FR 14267) and September 27, 2019 (84 FR 
51055), the EPA finalized clean data determinations (CDD) for the Provo 
and Salt Lake City NAAs, respectively. As provided at 40 CFR 51.1015(a) 
in the PM2.5 SIP Requirements Rule, this determination by 
the EPA that the Provo and Salt Lake City Moderate 2006 24-hour 
PM2.5 NAAs suspended the requirements for the State to 
submit an attainment demonstration, provisions demonstrating timely 
implementation of RACM/RACT, a RFP plan, quantitative milestones and 
quantitative milestone reports, and contingency measures. However, 
based on the EPA's longstanding policy, the BACM/BACT requirement of 
CAA section 189(b)(1)(B) is independent of attainment. Thus, the CDD 
did not suspend the obligation for UDAQ to submit any applicable 
outstanding BACM/BACT requirements or other requirements that are 
independent of attainment (NNSR and base-year emissions inventories).
    On February 15, 2019, UDAQ submitted the Serious 2006 24-hour 
PM2.5 SIP for the Salt Lake City NAA. Under CAA section 
110(k)(1)(B), the Salt Lake City Serious 2006 24-hour PM2.5 
SIP became complete by operation of law on August 15, 2019. 
Additionally, UDAQ submitted BACM/BACT analyses on February 4, 2019 for 
the Provo NAA. The revisions to area source rules for the NAAs were 
submitted on April 19, 2018, May 21, 2020 and July 21, 2020, and 
revisions to the Utah SIP Section IX.H.11, 12 and 13 for the NAAs were 
submitted on December 16, 2014, January 19, 2017 and February 15, 2019. 
The revisions submitted on January 19, 2017 and February 15, 2019, for 
Utah SIP Section IX.H.11, 12 and 13, supersede the December 16, 2014 
submission; therefore, we are not acting on the December 16, 2014 
revisions, but are fully acting on Utah SIP Section IX.H.13 from the 
January 19, 2017 submission and Utah SIP Section IX.H.11 and 12 from 
the February 15, 2019 submission. Any reference to the December 16, 
2014 submission for Utah SIP Sections IX.H.11, 12 and 13, and any 
reference to the January 19, 2017 submittal for Utah SIP Section 
IX.H.11 and 12, are for informational purposes only. Additionally, on 
October 9, 2020, UDAQ submitted draft revisions to Kennecott's Power 
Plant in Utah SIP Section IX.H.12.i.i.C and the accompanying R307-110-
17 revisions for the EPA to parallel process.
    We are acting on these remaining Serious 2006 24-hour 
PM2.5 SIP elements for the Salt Lake City and Provo NAAs, 
that were not suspended with the CDDs, to allow for our action on the 
2006 24-hour PM2.5 redesignation requests discussed in 
Section II.C below of this document.
1. Base-Year Emissions Inventories
    CAA section 172(c)(3) requires that each SIP include a 
comprehensive, accurate, current inventory of actual emissions from all 
sources of the relevant pollutant or pollutants in the NAAs. This base-
year emissions inventory should provide a state's best estimate of 
actual emissions from all sources of the relevant pollutants in the 
area, including all emissions that contribute to the formation of a 
particular NAAQS pollutant. For the 2006 24-hour PM2.5 
NAAQS, the base-year inventory must include direct PM2.5 
emissions, separately reported filterable and condensable 
PM2.5 emissions, and emissions of all chemical precursors to 
the formation of

[[Page 71030]]

secondary PM2.5: Nitrogen oxides (NOX), sulfur 
dioxide (SO2), volatile organic compounds (VOC), and ammonia 
(NH3).\11\
---------------------------------------------------------------------------

    \11\ 40 CFR 51.1008.
---------------------------------------------------------------------------

    The most current base year for emissions inventories for the Provo 
and Salt Lake City NAAs was for 2017, which was made available to the 
public for comment (and a public hearing if requested) in the January 
13, 2020 PM2.5 maintenance plans/redesignation requests 
submittal. The base-year inventories are based on the most current and 
accurate information available to UDAQ at the time of the submittal. 
The 2017 base-year inventories comprehensively address all source 
categories in the Provo and Salt Lake City NAAs and were developed 
consistent with the EPA's inventory guidance.
    In Section II.C.4.a below, the EPA provides a detailed analysis of 
the 2017 base-year emissions inventories for the Provo and Salt Lake 
City NAAs, which were submitted for the 2006 24-hour PM2.5 
maintenance plans. Direct PM2.5 and all PM2.5 
precursors are included in the 2017 base-year emissions inventories, 
and filterable and condensible direct PM2.5 emissions are 
identified separately. For these reasons, and with the EPA's detailed 
analysis in Section II.C.4.a below, the EPA is proposing to approve the 
2017 base-year emissions inventories for the Provo and Salt Lake City 
NAAs as meeting the requirements of CAA section 172(c)(3), 40 CFR 
51.1008(a)(1) and 40 CFR 51.1008(b)(1).
2. NNSR
    CAA section 172(c)(5) requires preconstruction and operating 
permits for new major stationary sources and major modifications 
locating in NAAs. Section 173 of the CAA outlines the minimum statutory 
requirements for a state's NNSR permit program and serves as the basis 
for the EPA's NNSR regulations for PM2.5 as promulgated in 
the 2008 PM2.5 NSR Rule published at 73 FR 28321, May 16, 
2008.\12\ The 2016 PM2.5 Regulatory Rule amended the 
definitions of (1) regulated NSR pollutant with regard to 
PM2.5 precursors, (2) major stationary source with regard to 
major sources locating in PM2.5 NAAs classified as Moderate 
and Serious, and (3) significant with regard to emissions of 
PM2.5 precursors. For Moderate 2006 24-hour PM2.5 
SIPs, CAA section 189(a)(1)(A) of subpart 4 applies, which requires 
states to include in their implementation plan a permit program 
addressing major stationary sources of the 2006 24-hour 
PM2.5 NAAQS that meets the requirements under CAA section 
173 of subpart 1. For a Serious 2006 24-hour PM2.5 SIP, CAA 
section 189(b)(3) of subpart 4 applies, which requires that for any 
Serious Area the terms ``major source'' and ``major stationary source'' 
include any stationary source or group of stationary sources located 
within a contiguous area and under common control that emits, or has 
the potential to emit, at least 70 tpy of PM2.5.
---------------------------------------------------------------------------

    \12\ 81 FR at 58107.
---------------------------------------------------------------------------

    An approvable NNSR program in a state's implementation plan must, 
at a minimum, meet the applicable program requirements set forth in the 
federal NNSR provisions at 40 CFR 51.165, which for PM2.5 
have been based on changes to the section made by the 2008 
PM2.5 NSR Rule.\13\ States with designated NAAs for a 
particular pollutant are required to adopt regulations consistent with 
those applicable plan requirements, including any subsequent rule 
changes that the EPA may make, and submit them to the EPA for approval 
as part of their SIP.
---------------------------------------------------------------------------

    \13\ Id.
---------------------------------------------------------------------------

    The Provo and Salt Lake City NAAs were classified as a Moderate NAA 
for the 2006 24-hour PM2.5 NAAQS on November 13, 2009 (74 FR 
58688). On May 10, 2017 (82 FR 21711), the Provo and Salt Lake City 
areas were reclassified from Moderate to Serious 2006 24-hour 
PM2.5 NAAs. The major source permitting threshold for a 
Moderate 2006 24-hour PM2.5 NAA is 100 tpy of direct 
PM2.5 or any PM2.5 precursor, and 70 tpy for a 
Serious 2006 24-hour PM2.5 NAA.
    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), which satisfies the outstanding NNSR requirement 
for the Provo and Salt Lake City Moderate and Serious 2006 24-hour 
PM2.5 NAAs.
3. BACM/BACT
a. Requirements for BACM/BACT
    For any Serious 2006 24-hour PM2.5 NAA, section 
189(b)(1)(B) of the Act requires that a state submit provisions to 
assure that BACM/BACT for the control of PM2.5 and 
PM2.5 precursors shall be implemented no later than four 
years after the date the area is reclassified as a Serious area. The 
EPA defines BACM (including BACT) as, among other things, the maximum 
degree of emissions reduction achievable for a source or source 
category, which is determined on a case-by-case basis considering 
energy, economic and environmental impacts, and other costs.\14\ We 
generally consider BACM a control level that goes beyond existing RACM-
level controls, for example by expanding the use of RACM controls or by 
requiring preventative measures instead of remediation.\15\ Indeed, as 
implementation of BACM and BACT is required when a Moderate NAA is 
reclassified as Serious due to its inability to attain the NAAQS 
through implementation of ``reasonable'' measures, it is logical that 
``best'' control measures should represent a more stringent and 
potentially more costly level of control.\16\ The level of stringency 
generally refers to the overall level of emissions reductions of a 
control measure or technology, or of such measures and technologies 
combined.
---------------------------------------------------------------------------

    \14\ State Implementation Plans for Serious PM10 
Nonattainment Areas, and Attainment Date Waivers for PM10 
Nonattainment Areas Generally; Addendum to the General Preamble for 
the Implementation of Title I of the Clean Air Act Amendments of 
1990 (``Addendum''), August 16, 1994; 59 FR 41998, 42010, 42013 
(Aug. 16, 1994). The General Preamble for the Implementation of 
Title I of the Clean Air Act Amendments of 1990 (``General 
Preamble'') was published at 57 FR 13498 (Apr. 16, 1992).
    \15\ Id. at 42011, 42013.
    \16\ Id. at 42009-42010.
---------------------------------------------------------------------------

    The PM2.5 SIP Requirements Rule explains that BACM/BACT 
are generally independent requirements, to be determined without regard 
to the specific attainment analysis (i.e., attainment demonstration) 
for the area.\17\ The EPA found it reasonable to interpret the statute 
as requiring a different analysis for determining BACM/BACT, i.e., that 
while RACM emphasizes the attainment needs of the area, BACM has a 
greater emphasis on identifying measures that are feasible to 
implement. The Addendum noted that the test for BACM puts a ``greater 
emphasis on the merits of the measure or technology alone,'' rather 
than on ``flexibility in considering other factors,'' in contrast to 
the approach for RACM/RACT.\18\
---------------------------------------------------------------------------

    \17\ 81 FR at 58081.
    \18\ 59 FR at 42011.
---------------------------------------------------------------------------

    Section 189(b)(1)(B) of the Act allows states, in appropriate 
circumstances, to delay implementation of BACM until four years after 
reclassification. Because the EPA reclassified the Provo and Salt Lake 
City areas as Serious NAAs for the 2006 24-hour PM2.5 NAAQS 
effective June 9, 2017 (82 FR 21711; May 10, 2017), the date four years 
after reclassification is June 9, 2021. In this case, however, all BACM 
for direct PM2.5 and PM2.5 precursors in the 
Provo and Salt Lake City areas must be implemented no later than 
December

[[Page 71031]]

31, 2019, which is the outermost statutory attainment date for the 
Provo and Salt Lake City areas under section 188(c)(2).\19\
---------------------------------------------------------------------------

    \19\ CAA section 189(b)(1)(B) establishes an outermost deadline 
(``no later than four years after the date the area is 
reclassified'') and does not preclude an earlier implementation 
deadline for BACM where necessary to satisfy the attainment 
requirements of the Act.
---------------------------------------------------------------------------

    Under the PM2.5 SIP Requirements Rule, control measures 
that can be implemented in whole or in part by the end of the fourth 
year after an area's reclassification to Serious are considered BACM, 
and control measures that can only be implemented after this period but 
before the attainment date are considered ``additional feasible 
measures.'' \20\ The EPA has defined ``additional feasible measures'' 
as ``those measures and technologies that otherwise meet the criteria 
for BACM/BACT but that can only be implemented in whole or in part 
beginning 4 years after reclassification of an area, but no later than 
the statutory attainment date of the area.'' \21\ Given that the 
statutory attainment date is less than three years from the effective 
date of the reclassification of the Provo and Salt Lake City areas, 
additional feasible measures are not required in this case.
---------------------------------------------------------------------------

    \20\ 40 CFR 51.1010(a)(4)(ii). ``Additional feasible measures'' 
may be necessary in certain circumstances to implement the 
requirements of CAA section 172(c)(6), which states that NAA plans 
shall include enforceable emission limitations and such other 
control measures, means or techniques, as well as schedules and 
timetables for compliance, as may be necessary or appropriate to 
provide for attainment of the NAAQS by the applicable attainment 
date.
    \21\ 40 CFR 51.1000.
---------------------------------------------------------------------------

    The Addendum and the PM2.5 SIP Requirements Rule explain 
that the BACM/BACT selection process for implementation of the 2006 24-
hour PM2.5 NAAQS is designed to take into account the local 
facts and circumstances and the nature of the air pollution problem in 
a given NAA. The following steps are used in determining BACM/BACT: (1) 
Develop a comprehensive emission inventory of the sources of directly 
emitted PM2.5 and PM2.5 precursors; (2) Identify 
existing and potential control measures for the sources in the 
inventory; (3) Evaluate the technological feasibility of potential 
control measures; (4) Evaluate the economic feasibility of potential 
control measures; and (5) Determine the earliest date by which a 
control measure or technology can be implemented in whole or in 
part.\22\
---------------------------------------------------------------------------

    \22\ Addendum at 42012-42014; 81 FR at 58084-58085.
---------------------------------------------------------------------------

    Additionally, the EPA believes that BACT or lowest achievable 
emission rate (LAER) provisions for new sources (as distinct from BACT 
for existing sources), or best available retrofit technology (BART) for 
existing sources, could potentially quality as BACM or BACT for 
purposes of meeting the Serious area attainment plan requirements.\23\ 
However, as discussed further in the PM2.5 SIP Requirements 
Rule, the EPA does not believe it is appropriate for a state to assume 
that just because a certain control technology was determined to meet 
BACT, LAER or BART criteria for a new source sometime in the past, that 
such a control will also automatically meet the criteria for BACM or 
BACT or additional feasible measures for attainment planning purposes, 
because the regulated pollutant or source applicability may differ and 
the analyses may be conducted years apart. Thus, a state may not simply 
rely on prior BACT, LAER or BART analyses for the purposes of showing 
that a source has also met BACT for the relevant 2006 24-hour 
PM2.5 NAAQS. Rather, the EPA expects that in Step 2 
(discussed above) of the BACM/BACT determination process, the state 
would identify such measures as ``existing measures'' that should be 
further evaluated as potential BACM or BACT, or additional feasible 
measures. At the same time, the EPA notes that the presence of 
previously installed control technology, and the technical and economic 
considerations that would be associated with upgrading to a measure 
that achieves greater reductions, is something that should be 
considered in the assessments of technological and economic feasibility 
of the newer measure.\24\
---------------------------------------------------------------------------

    \23\ See 81 FR at 58086.
    \24\ Id.
---------------------------------------------------------------------------

    Once these analyses are complete, a state must use this information 
to develop enforceable control measures and submit them to the EPA for 
evaluation under CAA section 110. We use these steps as guidelines in 
our evaluation of the BACM measures and related analyses in the Provo 
and Salt Lake City 2006 24-hour PM2.5 Serious SIP.
b. Requirements for the Control of PM2.5 Precursors
    The composition of PM2.5 is complex and highly variable 
due in part to the large contribution of secondary PM2.5 to 
total fine particle mass in most locations, and to the complexity of 
secondary particle formation processes. A large number of possible 
chemical reactions, often non-linear in nature, can convert gaseous 
SO2, NOX, VOC, and NH3 to 
PM2.5, making them precursors to PM2.5.\25\ 
Formation of secondary PM2.5 may also depend on atmospheric 
conditions, including solar radiation, temperature, and relative 
humidity, and the interactions of precursors with preexisting particles 
and with cloud or fog droplets.\26\
---------------------------------------------------------------------------

    \25\ Air Quality Criteria for Particulate Matter (EPA/600/P-99/
002aF, Oct. 2004), Chapter 3.
    \26\ Regulatory Impact Analysis for the Final Revisions to the 
National Ambient Air Quality Standards for Particulate Matter (EPA/
452/R-12-005, December 2012), at 2-1.
---------------------------------------------------------------------------

    As explained in the PM2.5 SIP Requirements Rule, the Act 
requires that the state evaluate all PM2.5 precursors for 
regulation unless, for any given PM2.5 precursor, it 
demonstrates to the Administrator's satisfaction that the precursor 
does not contribute significantly to 2006 24-hour PM2.5 
levels that exceed the NAAQS in the NAA.\27\ The CAA does not define 
the term ``precursor'' for purposes of PM. The statutory definition of 
``air pollutant,'' however, provides that the term ``includes any 
precursors to the formation of any air pollutant, to the extent the 
Administrator has identified such precursor or precursors for the 
particular purpose for which the term `air pollutant' is used.'' \28\ 
The EPA has identified SO2, NOX, VOC, and 
NH3 as precursors to the formation of PM2.5. 
Accordingly, the BACM/BACT requirements of subpart 4 apply to emissions 
of all four precursor pollutants and direct PM2.5 from all 
types of stationary, area, and mobile sources, except as otherwise 
provided in the Act (e.g., CAA section 189(e)).
---------------------------------------------------------------------------

    \27\ See 81 FR at 51018-58019.
    \28\ See CAA section 302(g).
---------------------------------------------------------------------------

    Section 189(e) \29\ of the Act requires that the control 
requirements for major stationary sources of PM2.5 also 
apply to major stationary sources of PM2.5 precursors, 
except where the Administrator determines that such sources do not 
contribute significantly to PM2.5 levels that exceed the 
standard in the area. Although section 189(e) explicitly addresses only 
major stationary sources, the EPA interprets the Act as authorizing it 
also to determine, under appropriate circumstances, that regulation of 
specific PM2.5 precursors from other

[[Page 71032]]

source categories in a given NAA is not necessary.\30\
---------------------------------------------------------------------------

    \29\ On Jan. 4, 2013, in NRDC v. EPA, the D.C. Circuit held that 
the EPA erred in implementing the 1997 PM2.5 NAAQS 
pursuant only to the general implementation requirements of subpart 
1, rather than also to the implementation requirements specific to 
particulate matter (PM10) in subpart 4, part D of title I 
of the CAA. The court reasoned that the plain meaning of the CAA 
requires implementation of the 1997 PM2.5 NAAQS under 
subpart 4 because PM2.5 particles fall within the 
statutory definition of PM10 and thus implementation of 
the PM2.5 NAAQS is subject to the same statutory 
requirements as the PM10 NAAQS. See 81 FR at 58013.
    \30\ Courts have upheld this approach to the requirements of 
subpart 4 for PM10. See, e.g., Assoc. of Irritated 
Residents v. EPA, et al., 423 F.3d 989 (9th Cir. 2005).
---------------------------------------------------------------------------

    The PM2.5 SIP Requirements Rule recognizes that the 
treatment of PM2.5 precursors is important in developing a 
PM2.5 plan.\31\ The rule provides flexibility for areas 
where a particular PM2.5 precursor or precursors may not 
contribute significantly to PM2.5 levels that exceed the 
NAAQS. The rule provides for optional precursor demonstrations that a 
state may submit to the EPA to establish that sources of particular 
precursors need not be regulated for purposes of attainment planning or 
in an NNSR permitting program for a specific NAA.
---------------------------------------------------------------------------

    \31\ See, e.g., 81 FR at 58017.
---------------------------------------------------------------------------

    The February 4, 2019 and February 15, 2019, submissions for the 
Provo and Salt Lake City discusses the five primary pollutants that 
contribute to the emissions in the NAAs (i.e., NOX, 
SO2, VOC, NH3, and directly emitted 
PM2.5). The majority of ambient PM2.5 collected 
during a typical cold-pool episode of elevated concentration is 
secondary particulate matter, generated from gaseous precursor 
emissions. The results of speciation studies led UDAQ to the conclusion 
that the exceedances of the 2006 24-hour PM2.5 NAAQS were a 
result of the increased portion of the secondary PM2.5, 
mainly ammonium nitrate, that was chemically formed in the air and not 
primary PM2.5 emitted directly into the troposphere.\32\ 
Because of the major role that precursors play within the Provo and 
Salt Lake City NAAs, UDAQ did not include any precursor demonstration. 
Thus, the requirement to ensure the implementation of BACM/BACT applies 
to direct PM2.5 and each of the four PM2.5 
precursors listed above.
---------------------------------------------------------------------------

    \32\ The study results can be found in the TSD for the state's 
February 15, 2019 action (available in the docket for this action).
---------------------------------------------------------------------------

    Based on the information provided in the Provo and Salt Lake City 
submissions and other information available to the EPA, we agree with 
UDAQ's conclusion that all four chemical precursors, including direct 
PM2.5, must be regulated for purposes of attaining and 
maintaining the 2006 24-hour PM2.5 NAAQS in the Provo and 
Salt Lake City NAAs.
c. BACM/BACT Analysis in the Serious PM2.5 SIP
(1) Identifying the Sources of PM2.5 and PM2.5 
Precursors
    The first step in determining BACM is to develop a detailed 
emissions inventory of the sources of direct PM2.5 and 
PM2.5 precursors that can be used with modeling to determine 
the effects of these sources on ambient PM2.5 levels. As 
discussed above in Section II.B.1 of this proposed rule, Chapter 4 
(Emission Inventory Data) of the Salt Lake City February 15, 2019 
submission and the General Inventory section of the Provo, February 4, 
2019 submission, contain the planning inventories for directly emitted 
PM2.5 and for all PM2.5 precursors 
(NOX, SO2, VOC, and NH3) for the Salt 
Lake City and Provo NAAs, along with supporting documentation to 
support these inventories. Based on these inventories, four general 
categories were established: Industrial point sources, on-road mobile 
sources, off-road mobile sources, and area sources. Area sources 
represent smaller, more numerous point sources, residential activities 
such as home heating, and some biogenic emissions.
    Based on this identification of stationary, area, and mobile 
sources of direct PM2.5, NOX, VOC, 
SO2, and NH3 in the Provo and Salt Lake City 
areas, we conclude that the February 4, 2019 and February 15, 2019 
submissions, respectively, appropriately identify all emission sources 
and source categories that must be subject to evaluation for potential 
control measures consistent with the requirements of subpart 4.
(2) Identification and Implementation of BACM/BACT
    As part of its process for identifying candidate BACM/BACT and 
considering the technical and economic feasibility of additional 
control measures, UDAQ reviewed the EPA's guidance documents on BACM, 
guidance documents on control measures for direct PM2.5, 
NOX, VOC, NH3, and SO2 emissions 
sources,\33\ and control measures implemented in other PM2.5 
NAAs in other states. UDAQ's evaluations of potential BACM/BACT for 
each source category identified above are found in ``Section 8. Control 
Strategies'' in the February 4, 2019 Provo submission and in the TSD 
supporting the February 15, 2019 Salt Lake City submission. In the 
following sections, we review key components of UDAQ's demonstrations 
concerning BACM/BACT for the identified sources of direct 
PM2.5, NOX, VOC, SO2, and 
NH3 emissions in the Provo and Salt Lake City NAAs. We 
provide a more detailed evaluation of our review of UDAQ's regulations 
in our TSD, which is in the docket.
---------------------------------------------------------------------------

    \33\ This is not an exhaustive list. Please refer to UDAQ's 
submittal for detailed references: Control Techniques Guidelines 
(CTG); Alternative Control Techniques (ACT); New Source Performance 
Standards (NSPS); Ozone Transport Commission's (OTC) model rules; 
PM2.5 Requirements Rule, 81 FR 58010; US EPA Fugitive 
Dust Background Document and Technical Information Document for BACM 
(September 1992); General Preamble, 57 FR 13498; and Addendum, 59 FR 
41998.
---------------------------------------------------------------------------

    The UDAQ's BACM/BACT process and control measure evaluations are 
described in detail in the February 4, 2019 submission, ``Section 8. 
Control Strategies'' for the Provo NAA and in the State's February 15, 
2019 TSD for the Salt Lake City NAA. For each identified source 
category, UDAQ identified its adopted control measures and potential 
additional control measures based on measures implemented in other 
areas, measures identified in EPA regulations or guidance (e.g., in 
control technique guidelines (CTGs), alternative control technique 
documents (ACTs), new sources performance standards (NSPSs), or in the 
EPA's ``Cost Analysis Models/Tools for Air Pollution Regulations''), or 
measures identified in prior EPA rulemaking documents (e.g., 
recommendations in SIP actions).\34\ UDAQ evaluated these potential 
additional control measures to determine whether implementation of the 
measures would be technologically and economically feasible in the 
Provo and Salt Lake City areas.
---------------------------------------------------------------------------

    \34\ The Cost Analysis Models/Tools for Air Pollution 
Regulations can be found at https://www.epa.gov/economic-and-cost-analysis-air-pollution-regulations/cost-analysis-modelstools-air-pollution.
---------------------------------------------------------------------------

    On April 19, 2018, May 21, 2020 and July 21, 2020, UDAQ submitted 
revisions and new rules to its area source rules R307-208, Outdoor Wood 
Boilers; R307-230, NOX Emission Limits for Natural Gas-Fired 
Water Heaters; R307-304, Solvent Cleaning; R307-335, Degreasing; R307-
343, Emissions Standards for Wood Furniture Manufacturing Operations; 
R307-344, Paper, Film, & Foil Coating; R307-345, Fabric & Vinyl 
Coating; R307-346, Metal Furniture Surface Coating; R307-347, Large 
Appliance Surface Coating; R307-348, Magnet Wire Coating; R307-349, 
Flat Wood Panel Coating; R307-350, Miscellaneous Metal Parts & Products 
Coating; R307-351, Graphic Arts; R307-352, Metal Containers, Closure & 
Coating; R307-353, Plastic Parts Coating; R307-354, Auto Body 
Refinishing; and R307-355, Control of Emissions from Aerospace 
Manufacture & Rework Facilities. Additionally, UDAQ provided BACM 
analysis for area source rules that were not revised, which include: 
R307-302, Solid Fuel Burning Devices; R307-303, Commercial Cooking; 
R307-307, Road Salting & Sanding; R307-309, Nonattainment and 
Maintenance Areas

[[Page 71033]]

for PM10 and PM2.5: Fugitive Emissions and 
Fugitive Dust; R307-312, Aggregate Processing Operations; R307-328, 
Gasoline Transfer and Storage; R307-341, Cutback Asphalt; R307-342, 
Adhesive and Sealants; R307-356, Appliance Pilot Light; R307-357, 
Consumer Products; and R307-361, Architectural Coatings. Our detailed 
analysis of these area source rule revisions submitted on April 19, 
2018, May 21, 2020, and July 21, 2020, and the BACM analyses for these 
area sources submitted on February 4, 2019 and February 15, 2019 for 
the Provo and Salt Lake City Serious 2006 24-hour PM2.5 NAAs 
can be found in our TSD in the docket.
    On February 15, 2019, Utah submitted revisions to SIP Section 
IX.H.11 (General Requirements: Control Measures for Area and Point 
Sources, Emission Limits and Operating Practices, PM2.5). 
This section of Utah's SIP applies to all sources addressed in Utah SIP 
sections IX.H.12 and 13, except as otherwise outlined in individual 
conditions in Sections IX.H.12 and 13. Our detailed analysis of the 
revisions submitted on February 15, 2019, for the Utah SIP Section 
IX.H.11, along with our analysis of UDAQs BACM/BACT analyses specific 
to Utah SIP Section IX.H.11, submitted on February 4, 2019 and February 
15, 2019 can be found in our TSD in the docket.
    On February 15, 2019, Utah submitted revisions to SIP Section 
IX.H.12 (Source-Specific Emission Limitations in Salt Lake City--UT 
PM2.5 Nonattainment Area), which sets emission limits and 
control measures for major stationary sources in the Salt Lake City 
2006 24-hour PM2.5 Serious NAA. These sources, which fall 
above the 70 tpy threshold for Serious 2006 24-hour PM2.5 
major sources \35\ defined in Utah R307-403 (Permits: New and Modified 
Sources in Nonattainment Areas and Maintenance Areas), include: (1) ATK 
Launch Systems Inc. Promontory; (2) Big West Oil Refinery; (3) Chemical 
Lime Company (Lhoist North America); (4) Chevron Products Company--Salt 
Lake Refinery; (5) Compass Minerals Ogden Inc.; (6) Hexel Corporation: 
Salt Lake Operations; (7) Holly Corporation: Holly Refining & Marketing 
Company (Holly Refinery); (8) Kennecott Utah Copper (KUC): Mine; (9) 
Kennecott Utah Copper (KUC): Power Plant; (10) Kennecott Utah Copper 
(KUC): Smelter and Refinery; (11) Nucor Steel Mills; (12) PacifiCorp 
Energy: Gadsby Power Plant; (13) Tesoro Refining and Marketing Company: 
Salt Lake City Refinery; (14) The Proctor & Gamble Paper Products 
Company; (15) Utah Municipal Power Association: West Valley Power 
Plant; (16) University of Utah: University of Utah Facilities; and (17) 
Hill Air Force Base. On February 15, 2019, UDAQ submitted the BACM/BACT 
analyses for each of these 17 sources. All other sources fall below the 
70 tpy threshold and are covered in the multiple area source rules 
discussed above. Our detailed analysis of the revisions submitted on 
February 15, 2019, for the Utah SIP Section IX.H.12, along with our 
analysis of UDAQs BACM/BACT analyses submitted on February 15, 2019, 
specific to Utah SIP Section IX.H.12, can be found in our TSD in the 
docket.
---------------------------------------------------------------------------

    \35\ 81 FR at 58152.
---------------------------------------------------------------------------

    Additionally, UDAQ submitted draft revisions on October 9, 2020, 
specific to Utah SIP Section IX.H.12.i.i.C (Kennecott Power Plant), 
which the state has asked the EPA to act on through parallel 
processing. This draft revision removes the startup/shutdown limits for 
the Kennecott Power Plant that was not supported within the BACM/BACT 
analysis submitted on February 15, 2019. The detailed analysis of our 
parallel process on the October 9, 2020, submission of draft revisions 
to Utah SIP Section IX.H.12.i.i.C (Kennecott Power Plant), can be found 
in our TSD in the docket, and our detailed discussion of how parallel 
processing works can be found in Section I.E above.
    On January 19, 2017, Utah submitted revisions to SIP Section 
IX.H.13 (Source-Specific Emission Limitations in Provo--UT 
PM2.5 Nonattainment Area), which sets emission limits and 
control measures for major stationary sources in the Provo 2006 24-hour 
PM2.5 Serious NAA. The sources in Section IX.H.13 include: 
(1) Brigham Young University: Main Campus; (2) Geneva Nitrogen Inc.: 
Geneva Nitrogen Plant; (3) McWane Ductile--Utah; (4) PacifiCorp Energy: 
Lake Side Power Plant; (5) Payson City Corporation: Payson City Power; 
(6) Provo City Power: Power Plant; and (7) Springville City 
Corporation: Whitehead Power Plant. UDAQ submitted BACM/BACT analyses 
for only two of these sources, McWane Ductile--Utah and PacifiCorp 
Energy: Lake Side Power Plant. The other five sources listed above fall 
below the 70 tpy threshold for Serious 2006 24-hour PM2.5 
major stationary sources,\36\ which is defined in Utah R307-403 
(Permits: New and Modified Sources in Nonattainment Areas and 
Maintenance Areas) rule. These remaining five sources (Brigham Young 
University, Geneva Nitrogen Plant, Payson City Power, Provo City Power, 
and Whitehead Power Plant) were either shut down (Geneva Nitrogen 
Plant) or have reduced their emissions to be minor sources (Brigham 
Young University, Payson City Power, Provo City Power, and Whitehead 
Power Plant). UDAQ uses Utah SIP Section IX.H. only for major 
stationary source emission limits or control measures; therefore, UDAQ 
has requested that EPA not act on the Utah SIP Section IX.H.13 portions 
for these facilities because the limits/measures are out of date and 
will be removed in future rulemakings. Since we have never approved 
these limits or sources into Utah SIP Section IX.H.13, and this section 
was only created in the December 16, 2014 submittal, UDAQ does not need 
to complete a 110(l) demonstration. We will only be acting on the 
McWane Ductile--Utah and PacifiCorp Energy: Lake Side Power Plant 
sections of Utah SIP Section IX.H.13, and on these sources' BACM/BACT 
determinations submitted by UDAQ on February 4, 2019. Our detailed 
analysis of the revisions submitted on January 19, 2017, along with our 
analysis of UDAQ's BACM/BACT analyses submitted on February 4, 2019, 
can be found in our TSD in the docket.
---------------------------------------------------------------------------

    \36\ Id.
---------------------------------------------------------------------------

    As to the other facilities originally submitted within Utah SIP 
Section IX.H.13, no additional discussion or action is necessary for 
the Geneva Nitrogen Plant due to its shutdown. The BACM/BACT analyses 
for the other facilities (Brigham Young University, Payson City Power, 
Provo City Power, and the Whitehead Power Plant) are now included in 
the individual BACM/BACT analyses for each area source rule. No 
additional discussion is needed as to these limits in Utah SIP Section 
IX.H.13, which as noted above are outdated, or on these facilities as 
individual sources. Our detailed analysis of the area source rules, 
along with our analysis of UDAQ's BACM/BACT analyses submitted on 
February 4, 2019 and February 15, 2019, can be found in our TSD in the 
docket.
    Additionally, on February 4, 2019 and February 15, 2019, UDAQ 
submitted BACM/BACT analyses for on-road and non-road mobile sources 
for the Provo and Salt Lake City Serious 2006 24-hour PM2.5 
NAAs, respectively. Our detailed analysis of these analyses can be 
found in our TSD in the docket.
(3) The EPA's Evaluation and Conclusion
    We have reviewed UDAQ's determination in the February 4, 2019 and 
February 15, 2019 submissions that the major stationary and area source

[[Page 71034]]

control measures represent BACM/BACT for direct PM2.5 and 
PM2.5 precursors within the Provo and Salt Lake City NAAs, 
respectively. In our review, we also considered our previous 
evaluations of UDAQ's rules in connection with our approval of 
revisions for Utah's R307 area source rules and RACM demonstration for 
the Provo and Salt Lake City Moderate 2006 24-hour PM2.5 
SIPs that were acted on.\37\ Based on this review, we believe that 
UDAQ's area source rules and the Utah SIP Part H emission limits 
provide for the implementation of BACM/BACT for major stationary 
sources and area sources of direct PM2.5 and 
PM2.5 precursors.
---------------------------------------------------------------------------

    \37\ See 81 FR 9343 (Feb. 25, 2016); 81 FR 71988 (Oct. 19, 
2016); 84 FR 52368 (Oct. 2, 2019); and 85 FR 10989 (Feb. 26, 2020).
---------------------------------------------------------------------------

    With respect to mobile sources, we believe that the programs 
developed and administered by UDAQ, along with the identified Federal 
requirements, provide for the implementation of BACM/BACT for direct 
PM2.5 and PM2.5 precursors in the Provo and Salt 
Lake City NAAs.
    For these reasons we propose to approve the revisions submitted on 
January 19, 2017, April 19, 2018, February 4, 2019, February 15, 2019, 
May 21, 2020 and July 21, 2020. We also propose to find that these 
submissions provide for the implementation of BACM/BACT for all sources 
of direct PM2.5 and PM2.5 precursors as 
expeditiously as practicable, for purposes of the 2006 24-hour 
PM2.5 NAAQS in the Provo and Salt Lake City areas, in 
accordance with the requirements of CAA section 189(b)(1)(B) and 40 CFR 
51.1010. We are also proposing to approve, through parallel processing, 
the October 9, 2020 draft submission of revisions to Utah SIP Section 
IX.H.12.i.i.C to remove the startup/shutdown limits that were not 
supported in the BACM/BACT determination of the Kennecott Power Plant. 
Additionally, we are proposing to approve the area source rule 
revisions submitted on April 19, 2018, May 21, 2020 and July 21, 2020, 
and to approve the BACM/BACT analyses submitted on February 4, 2019 and 
February 15, 2019. We are also proposing to approve the revisions to 
Utah SIP Sections IX.H.11 and 12, submitted on February 15, 2019; 
revisions to Utah SIP Section IX.H.13, submitted on January 19, 2017; 
and draft revisions submitted on October 9, 2020, for the Provo and 
Salt Lake City Serious 2006 24-hour PM2.5 NAAs. Our detailed 
analyses can be found in the EPA TSD in the docket.

C. Do the redesignation requests and maintenance plans meet CAA 
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 such area must meet all 
requirements applicable to the area under section 110 and part D of the 
CAA.
    The September 4, 1992 Calcagni Memorandum outlines how to assess 
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, submitted maintenance plans for the Salt Lake 
City and Provo areas (located within Utah SIP Sections IX.A.36 and 27, 
respectively), and requested that the EPA redesignate the area to 
attainment for 2006 24-hour PM2.5.
    The sections below discuss how Utah's redesignation requests and 
maintenance plans meet the requirements of the Act for redesignation of 
the Provo and Salt Lake City areas to attainment for the 2006 24-hour 
PM2.5 NAAQS.
1. Attainment of the 2006 24-Hour PM2.5 NAAQS
    To redesignate an area from nonattainment to attainment, the EPA 
must determine that the area has attained the applicable NAAQS. See CAA 
section 107(d)(3)(E)(i). 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, which 
must be quality assured, quality-controlled, and certified in the EPA's 
Air Quality System (AQS), must show that the most recent three years 
(2017-2019) of valid PM2.5 98th percentile mass 
concentrations are below the 2006 PM2.5 24-hour 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.
    Between 2017 and 2019, Utah operated two and five PM2.5 
monitors in the Provo and Salt Lake City NAAs, respectively. The EPA 
reviewed the PM2.5 ambient air monitoring data from the 
Provo monitors, Lindon (AQS site 49-049-4001) and Spanish Fork (AQS 
site 49-049-5010),\38\ and from the Salt Lake City monitors, Bountiful 
(AQS site 49-011-0004), Rose Park (AQS site 49-035-3010), Hawthorn (AQS 
site 49-035-3006), Herriman #3 (AQS site 49-035-3013), and Erda (AQS 
site 49-045-0004).\39\
---------------------------------------------------------------------------

    \38\ The Provo NAA had one monitor (North Provo, 49-049-0002) 
shut down near the end of 2018 due to safety issues at the site, and 
UDAQ is working to reestablish the monitor at a new site.
    \39\ The Salt Lake City NAA had two monitors shut down due to 
the loss of each site, and UDAQ is working to reestablish the 
monitors at new sites. These monitors are Brigham City (49-003-
0003), which shutdown in June 2019, and Ogden 2 (49-057-0002), which 
shut down in May 2019. A new site for Ogden 2 was established in 
Weber County (Harrisville, 49-057-1003) in September 2019. UDAQ is 
still working with Box Elder County on new potential sites.
---------------------------------------------------------------------------

    As part of the redesignation requests for the Provo and Salt Lake 
City NAAs, UDAQ submitted ambient air quality data from the monitoring 
sites, which had been quality-assured and placed in AQS on a quarterly 
basis. The 98th percentile 2017-2019 design values for the monitors in 
the Provo and Salt Lake City NAAs are found in Table 1 below, and 
support the conclusion that the areas have attained the 2006 24-hour 
PM2.5 NAAQS.
---------------------------------------------------------------------------

    \40\ The Salt Lake City near-road PM2.5 monitoring 
site (AQS ID 49-035-4002) was established and began recording data 
on January 1, 2019. The 98th percentile daily average concentration 
for 2019 at this PM2.5 near-road monitor was 31.0 
[micro]g/m\3\; however, the one year of available data is not 
sufficient for calculating a design value. Additional discussion of 
the EPA's position as to Salt Lake City's PM2.5 near-road 
monitor can be found in the final rule signed by the Region 8 
Regional Administrator on October 29, 2020, determining that the 
Salt Lake City Serious 2006 24-hour PM2.5 NAA attained by 
the Serious attainment date.

[[Page 71035]]



               Table 1--Provo and Salt Lake City 2006 24-Hour PM2.5 NAAs 2017-2019 98th Percentiles and Design Values ([micro]g/m\3\) \40\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                 98th percentiles ([micro]g/m\3\)            2017-2019
                                                                                         ------------------------------------------------  Design value
                    NAA                            Monitoring site            AQS ID                                                        ([micro]g/
                                                                                               2017            2018            2019            m\3\)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Provo.....................................  Lindon......................     49-049-4001            28.9            28.4            21.2              26
                                            Spanish Fork................     49-049-5010            27.6            49.6            17.5              32
Salt Lake City............................  Bountiful...................     49-011-0004            35.2            25.7            19.3              27
                                            Rose Park...................     49-035-3010            32.4            29.2            27.9              30
                                            Hawthorn....................     49-035-3006            35.7            26.2            27.3              30
                                            Herriman #3.................     49-035-3013            28.2            29.0            18.8              25
                                            Erda........................     49-045-0004            20.9            30.6            22.9              25
--------------------------------------------------------------------------------------------------------------------------------------------------------

    As explained above, quality-assured, quality-controlled, and 
certified air quality monitoring data were collected for each year from 
2017 through 2019 in accordance with an approved annual monitoring 
network plan (AMNP) for each year. The EPA has reviewed this data and 
concluded that it shows that the areas attained by the Serious 
attainment date of December 31, 2019.\41\
---------------------------------------------------------------------------

    \41\ The final determination of attainment by the Serious 2006 
24-hour PM2.5 attainment date was signed by the Region 8 
Regional Administrator on October 29, 2020.
---------------------------------------------------------------------------

    Further information on PM2.5 monitoring is in 
Subsections IX.A.27.b(1) and IX.A.36.b(1) of the Provo and Salt Lake 
City maintenance plans, respectively. Additionally, on October 29, 
2020, the Region 8 Regional Administrator signed the final rule, which 
finalized a determination that the Provo and Salt Lake City NAAs 
attained by the Serious attainment date of December 31, 2019. We have 
evaluated the ambient air quality data and believe that Utah has 
adequately demonstrated that the 2006 24-hour PM2.5 NAAQS 
has been attained in the Provo and Salt Lake City areas and that the 
two areas attained by their Serious 2006 24-hour PM2.5 
attainment date.
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).
    Those states containing Moderate 2006 24-hour PM2.5 NAAs 
were required to submit a SIP by December 31, 2014, demonstrating 
attainment of the 2006 24-hour PM2.5 NAAQS by December 31, 
2015. UDAQ submitted the Moderate 2006 24-hour PM2.5 SIPs 
for the Provo and Salt Lake City NAAs on December 16, 2014, with 
additional revisions submitted on January 19, 2017. On May 10, 2017 (82 
FR 21711), the EPA published a final rule reclassifying the Salt Lake 
City and Provo areas as ``Serious'' nonattainment under subpart 4, 
based on the EPA's determination that the area could not practicably 
attain the 2006 24-hour PM2.5 standards by the December 31, 
2015 attainment date. This reclassification became effective on June 9, 
2017. The reclassification was based on the EPA's evaluation of ambient 
air quality data from the 2013-2015 period, indicating that it was not 
practicable for certain monitoring sites within the Salt Lake City and 
Provo areas to show PM2.5 design values at or below the 
level of the 2006 24-hour PM2.5 NAAQS by December 31, 2015.
    Section 107(d)(3)(E)(ii) of the CAA states that for NAAs to be 
redesignated to attainment, it must be determined that the 
Administrator has fully approved the applicable implementation plan for 
the areas 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 the 2006 24-hour 
PM2.5 NAAs into the Utah SIP. Additionally, we completed a 
CDD for the Provo and Salt Lake City 2006 24-hour PM2.5 NAAs 
on April 10, 2019 (84 FR 14267) and on September 27, 2019 (84 FR 
51055), respectively. With these final rules, the EPA suspended the 
obligation for Utah to make submissions to meet certain CAA 
requirements related to attainment of the 2006 24-hour PM2.5 
NAAQS for Moderate and Serious NAAs. These suspended CAA requirements 
are: (1) Attainment demonstration (Moderate and Serious); (2) projected 
emissions inventory (Moderate and Serious); (3) RACM/RACT (Moderate); 
(4) RFP (Moderate and Serious); (5) motor vehicle emission budgets 
(MVEB) (Moderate and Serious); (6) contingency measures (Moderate and 
Serious); and (7) quantitative milestones (Moderate and Serious).
    The CDD did not suspend Utah's obligation to submit CAA 
requirements not related to demonstrating attainment, which includes 
the base-year emission inventory, NNSR revisions, and BACM/BACT for the 
Provo and Salt Lake City NAAs. The base-year emission inventory 
requirement for the Moderate and Serious Provo and Salt Lake City NAAs, 
will be based on our approval of the base-year inventory submitted in 
the January 13, 2020 submittal of the maintenance plans. Our analysis 
of the base-year inventory is discussed in Section II.C.4.a below and 
in Section II.B.1 above.
    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), which satisfies the outstanding NNSR requirement 
for the Provo and Salt Lake City Moderate and Serious 2006 24-hour 
PM2.5 NAAs and is discussed above in Section II.B.2. above.
    The remaining CAA requirement that was not suspended with the April 
10, 2019 (84 FR 14267) and the September 27, 2019 (84 FR 51055), CDD 
for the Provo and Salt Lake City 2006 24-hour PM2.5 NAAs, 
respectively, is BACM/BACT for the Serious 2006 24-hour 
PM2.5 SIPs. Our analysis that completes this remaining 
requirement is discussed in our TSD, with a brief discussion in Section 
II.B.3. above.
    We have evaluated the actions above and have determined that 
through these actions, the State of Utah has a fully approved Provo and 
Salt Lake City 2006 24-hour 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

[[Page 71036]]

control regulations, and other permanent and enforceable reductions.
    As briefly discussed above in Section II.B.3 and in further detail 
in our TSD, Utah has implemented multiple area source rules, I/M 
Programs, and emission limits for stationary sources in the Provo and 
Salt Lake City NAAs.
    Additionally, within Section IX.A.27.b.1.c. and IX.A.36.b.3.a. of 
the Provo and Salt Lake City 2006 24-hour PM2.5 maintenance 
plan, respectively, UDAQ provides an assessment of the ambient air 
quality data collected at the monitors in these two NAAs 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 the 98th percentile 
average of the 24-hour data in the Provo and Salt Lake City 2006 24-
hour PM2.5 NAAs, as well as the annual arithmetic mean, 
which assisted in understanding the trends. The Provo and Salt Lake 
City 2006 24-hour PM2.5 NAAs were only designated 
nonattainment for the 2006 24-hour PM2.5 NAAQS, however, the 
annual arithmetic mean is useful information in showing the decrease in 
emissions. The cold-pool temperature inversions during winter, 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 the 24-hour data trend is downward, indicating 
improvement of a little less than 1 [micro]g/m\3\ per year for both the 
Provo and Salt Lake City 2006 24-hour PM2.5 NAAs. Episodic 
variability is reduced when reviewing the annual mean values of 
PM2.5 concentrations from 2000-2018. Graphing the annual 
mean PM2.5 concentration data reveals a decreasing trend, 
which indicates an improvement of 3 [micro]g/m\3\ and 4.3 [micro]g/m\3\ 
over this 18-year span for the Provo and Salt Lake City NAAs, 
respectively.
    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 believe that 
the improvement in air quality in the Provo and Salt Lake City NAAs 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 
which meets 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, a state must submit a revised 
maintenance plan demonstrating attainment for the 10 years following 
the initial 10-year period. The maintenance plan must also contain a 
contingency plan to ensure prompt correction of any violation of the 
NAAQS.\42\ The EPA's interpretations of the CAA section 175A 
maintenance plan requirements are generally provided in the General 
Preamble \43\ 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.
---------------------------------------------------------------------------

    \42\ Sections 175A(b) and (d).
    \43\ 57 FR 13498, at 13563.
---------------------------------------------------------------------------

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 Provo and Salt Lake City 2006 24-hour 
PM2.5 maintenance plans for the two NAAs on January 13, 
2020. This submittal contains a base year inventory for 2017, interim-
year projection inventory for 2026, and a projected maintenance 
inventory of 2035. The emissions in the inventories include sources of 
direct PM2.5 and PM2.5 precursor emissions 
located within a regional area called a modeling domain. UDAQ modeled 
two different domain sizes and grid resolutions: A 4 kilometer (km) 
coarse grid and a 1.33 km fine grid.\44\ 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, and was used to show movement of pollutants at the 
boundaries of the nested fine grid domain.
---------------------------------------------------------------------------

    \44\ See January 13, 2020 State of Utah submittal for Provo and 
Salt Lake City 2006 24-hour PM2.5 Maintenance Plans; 
Figures IX.A.27.4. and IX.A.36.4, respectively, titled ``CAMx 
Photochemical Modeling Domain in Two-Way Nested Configuration.''
---------------------------------------------------------------------------

    Since the coarse domain was so large, the 1.33 km fine domain or a 
``core area'' within this domain was identified, within which a greater 
degree of accuracy was applied. 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, outside the core area, the 
2014 National Emissions Inventory (NEI) was used in the analysis. There 
were four general categories of sources included in these inventories: 
Point sources, area sources, on-road mobile sources and non-road mobile 
sources.
    For each of these source categories, the pollutants that were 
inventoried were PM2.5, SO2, NOX, VOC 
and NH3. More detailed descriptions of the 2017 base-year 
inventory and the 2026 and 2035 projection inventories can be found in 
Sections IX.A.27.c and IX.A.36.c. Maintenance Plan, Subsection (2) 
Attainment Inventory, for the Provo and Salt Lake City NAAs, 
respectively, and in the State of Utah's TSD. Utah's submittal contains 
detailed emission inventory information that was prepared in accordance 
with the EPA's emission inventory guidance.\45\ Summary of emission 
figures from the 2017 base year and emission projections for 2026 and 
2035 are provided in Table 2 and Table 3, below, for the Provo and Salt 
Lake City, respectively.
---------------------------------------------------------------------------

    \45\ 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).

[[Page 71037]]



                                Table 2--Provo 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...................          1.75          0.29      2.04      5.01    13.32     6.54     0.06
                                              Mobile Sources.................  ............  ............      0.83      15.4     9.07     0.43     0.09
                                              Non-Road.......................  ............  ............      0.21      3.07     1.66        0     0.01
                                              Point Sources..................          0.18          0.12       0.3      1.12     0.18     0.42     0.05
                                                                              --------------------------------------------------------------------------
                                                 2017 Total..................  ............  ............      3.38      24.6    24.23     7.39     0.22
--------------------------------------------------------------------------------------------------------------------------------------------------------
2026........................................  Area Sources...................          1.89          0.32      2.21      3.56     14.2     6.38     0.05
                                              Mobile Sources.................  ............  ............      0.42      5.79     4.58     0.36     0.05
                                              Non-Road.......................  ............  ............      0.14      2.14     1.65     0.01     0.01
                                              Point Sources..................          0.19          0.12      0.31      0.97     0.17     0.44     0.06
                                                                              --------------------------------------------------------------------------
                                                 2026 Total..................  ............  ............      3.08     12.46     20.6     7.19     0.17
--------------------------------------------------------------------------------------------------------------------------------------------------------
2035........................................  Area Sources...................          2.06          0.35      2.41      3.67    16.32     6.24     0.05
                                              Mobile Sources.................  ............  ............      1.41      5.74     6.49     0.44     0.05
                                              Non-Road.......................  ............  ............      0.13      1.84      1.8     0.01     0.01
                                              Point Sources..................          0.19          0.12      0.31      0.97     0.17     0.44     0.06
                                                                              --------------------------------------------------------------------------
                                                 2035 Total..................  ............  ............      4.26     12.22    24.78     7.13     0.17
--------------------------------------------------------------------------------------------------------------------------------------------------------


                           Table 3--Salt Lake City 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...................          5.02          1.11      6.13     13.55    45.98    14.21     0.21
                                              Mobile Sources.................  ............  ............      2.28     44.21    30.12     1.28     0.31
                                              Non-Road.......................  ............  ............      0.96     18.12     8.89     0.02     0.35
                                              Point Sources..................          2.97          0.97      3.94     17.01     6.52     0.34     3.78
                                                                              --------------------------------------------------------------------------
                                                 2017 Total..................  ............  ............     13.31     92.89    91.51    15.85     4.65
--------------------------------------------------------------------------------------------------------------------------------------------------------
2026........................................  Area Sources...................          5.19          1.15      6.34      8.54    43.99    14.19      0.2
                                              Mobile Sources.................  ............  ............      1.34     19.63    15.96     1.09     0.16
                                              Non-Road.......................  ............  ............      0.72     14.64     8.85     0.02     0.44
                                              Point Sources..................          4.19          1.38      5.57     22.61     7.26     0.48      3.5
                                                                              --------------------------------------------------------------------------
                                                 2026 Total..................  ............  ............     13.97     65.42    76.06    15.78      4.3
--------------------------------------------------------------------------------------------------------------------------------------------------------
2035........................................  Area Sources...................          5.37          1.19      6.56      8.69    47.17    14.21      0.2
                                              Mobile Sources.................  ............  ............      1.39     18.91    18.93     1.19     0.15
                                              Non-Road.......................  ............  ............      0.67     13.32      9.7     0.03     0.51
                                              Point Sources..................          4.19          1.38      5.57     22.62     7.26     0.48      3.5
                                                                              --------------------------------------------------------------------------
                                                 2035 Total..................  ............  ............     14.19     63.54    83.06    15.91     4.36
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Based on our review, we have determined that Utah prepared an 
adequate attainment inventory for the Provo and Salt Lake City 2006 24-
hour PM2.5 NAAs. Additionally, the 2017 base-year inventory 
satisfies the outstanding requirement for the Serious Provo and Serious 
Salt Lake City NAAs that were not suspended with the CDDs finalized on 
April 10, 2019 (84 FR 14267) and September 27, 2019 (84 FR 51055), 
respectively.
b. Maintenance Demonstration
    The Calcagni Memorandum explains 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 Provo and Salt 
Lake City areas used a regional photochemical model.
    Before the development of the Provo and Salt Lake City 2006 24-hour 
PM2.5 maintenance plans, UDAQ conducted a technical analysis 
to support the development of the Serious SIP for the Salt Lake City 
2006 24-hour 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 episode selection to determine 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 Provo and Salt Lake City maintenance plans, 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 Provo and Salt Lake City

[[Page 71038]]

maintenance plans, with enhancements that included snow chemistry and 
topographical and surface albedo refinements. The emissions processing 
model that UDAQ used in conjunction with CAMx was the Sparse Matrix 
Operator Kernel Emissions Modeling System (SMOKE) version 3.6.5,\46\ 
which prepares the annual emissions inventory for use in the air 
quality model.
---------------------------------------------------------------------------

    \46\ https://www.cmascenter.org/smoke/.
---------------------------------------------------------------------------

    Activity profiles and their associated cross reference files from 
the EPA's 2011v6 \47\ modeling platform were used by UDAQ. For 
stationary non-point and mobile sources, UDAQ used spatial surrogates 
from the EPA Clearinghouse for Inventories and Emissions Factors 
(CHIEF),\48\ which were used to distribute emissions in space across 
the modeling domain. Emissions from point sources were placed at the 
specific location of the sources. Additionally, if reliable local 
information was available, UDAQ modified or developed the profiles and 
surrogates to reflect this information.
---------------------------------------------------------------------------

    \47\ https://www.epa.gov/air-emissions-modeling/2011-version-6-air-emissions-modeling-platforms.
    \48\ https://www.epa.gov/chief.
---------------------------------------------------------------------------

    Meteorological inputs were derived using the Weather Research and 
Forecasting \49\ (WRF) Advanced Research WRF (WRF-ARW) model to prepare 
meteorological datasets for UDAQ to use with the photochemical model. 
WRF-ARW had reasonable ability to replicate the vertical temperature 
structure of the boundary layer (i.e., the temperature inversion); 
however, UDAQ found that WRF-ARW had difficulty reproducing the 
inversion when the inversion was shallow and strong (i.e., an 8-degree 
temperature increase over 100 vertical meters). UDAQ provides 
additional information on these models in their TSD.
---------------------------------------------------------------------------

    \49\ https://www.mmm.ucar.edu/weather-research-and-forecasting-model.
---------------------------------------------------------------------------

    Part of the modeling exercise that UDAQ completed for the Provo and 
Salt Lake City maintenance plans was to test whether the model could 
successfully replicate the PM2.5 mass and composition 
observed during prior episodes of elevated PM2.5 
concentrations. The selection of an appropriate episode(s) should 
determine the meteorological episode that helps produce the best air 
quality modeling performance.
    Based on EPA guidance,\50\ 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 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 Provo monitoring station 
(Lindon) was strongly correlated during the January 2011 episode (R\2\ 
= 0.89) compared to the other episodes (R\2\ = 0.81 for the December 
2013 episode; and R\2\ = 0.05 for the February 2016 episode). The Salt 
Lake City monitoring station (Hawthorne) linear regression analysis 
showed similar results to the Provo monitoring site, in that the 
performance of the January 2011 episode was strongly correlated (R\2\ = 
0.80) compared to the other episodes (R\2\ = 0.54 for the December 2013 
episode and R\2\ = 0.69 for the February 2016 episode). Therefore, UDAQ 
selected the January 2011 episode to conduct the modeled maintenance 
demonstration work for the Provo and Salt Lake City areas. A 
comprehensive discussion of the meteorological model performance for 
all three of these episodes can be found in the TSD submitted by UDAQ.
---------------------------------------------------------------------------

    \50\ Guidance on the Use of Models and Other Analyses for 
Demonstrating Attainment of Air Quality Goals for Ozone, 
PM2.5, and Regional Haze (EPA, Apr. 2007).
---------------------------------------------------------------------------

    UDAQ completed a comparison of the 24-hour average modeled and 
observed PM2.5 during the January 1-10, 2011 episode at the 
Provo monitoring station (Lindon) and at the Salt Lake City monitoring 
station (Hawthorne), and the results showed that the model overall 
captured the daily 24 hour average temporal variation in 
PM2.5 well. A more detailed analysis of this episode for 
both the Provo and Salt Lake City monitoring sites (Lindon and 
Hawthorne, respectively) can be found in the TSD submitted by UDAQ.
    Overall, UDAQ concluded that the model performed well in 
replicating the buildup and dispersal of PM2.5 in the Provo 
and Salt Lake City NAAs, and thus the model could be used for air 
quality planning purposes. UDAQ then developed a 2017 baseline model 
simulation using 2017 emissions data, but using the WRF-ARW 
meteorological data for the 2011 episode. The 2017 baseline modeling 
and the 2017 baseline monitoring data design values are used to 
simulate possible future PM2.5 levels by projecting from the 
2017 emissions to future year emissions. The results of the future year 
modeling are described below.
    With acceptable model performance, the model can be used 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, and then compared to the NAAQS (35 [micro]g/m\3\). 
When the FDV is smaller than the NAAQS at every monitor in the NAA, 
this 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 the time that the EPA finalizes action of the plan, the ten-year 
end date is uncertain. To be conservative, UDAQ projected an attainment 
date of 2035, which is fifteen years after Utah submitted the Provo and 
Salt Lake City maintenance plans. Additionally, UDAQ modeled a ``spot-
check'' assessment of 2026.
    For any monitor, the FDV is greatly influenced by the existing air 
quality at the specific location. This can be quantified and expressed 
as a Baseline Design Value (BDV). The BDV is consistent with the form 
of the 2006 24-hour PM2.5 NAAQS, which is the 98th 
percentile value averaged over a three-year period. The quantification 
of the BDV for each monitor in Provo and Salt Lake City, is included in 
the TSD submitted by UDAQ.
    Several values were excluded when UDAQ calculated the BDVs in the 
Provo NAA. UDAQ utilized the EPA's ``Exceptional Events Rule,'' \51\ 
which allows states to exclude certain air quality data due to 
exceptional events (e.g., wildfires, dust storms, etc.). Two large 
local wildfires were observed during the summer of 2018 that affected 
the PM2.5 values at the Spanish Fork monitor in the Provo 
NAA, but even when the atypical wildfire data is included in the 
baseline design value the level is still below the 2006 24-hour 
PM2.5 NAAQS, at 35.4 [micro]g/m\3\. Since the design value 
complies with the NAAQS, the wildfire events are not considered 
regulatorily significant exceptional events under the Exceptional 
Events Rule because they did not cause an exceedance or a violation of 
the NAAQS.\52\
---------------------------------------------------------------------------

    \51\ 81 FR 68216 (Oct 3, 2016).
    \52\ 40 CFR 50.14.
---------------------------------------------------------------------------

    Although the wildfires did not cause exceptional events, which 
would have needed the EPA's concurrence under the Exceptional Events 
Rule, Utah excluded the values from those days from its modeling, so as 
to produce more representative projections of future air quality. This 
exclusion was consistent with EPA guidance on addressing instances 
where air quality data is influenced by atypical, extreme, or 
unrepresentative.\53\ This Additional

[[Page 71039]]

Methods Guidance identifies the most common determinations and analyses 
not covered by the Exceptional Events Rule, and clarifies for each of 
them whether there is a separate, existing mechanism under which the 
exclusion, selection, or adjustment of air quality monitoring data may 
be appropriate. One example is certain modeling analyses under EPA's 
Guideline on Air Quality Models \54\ including modeling analyses used 
for estimating base and future year design values for ozone and 
PM2.5 attainment demonstrations.
---------------------------------------------------------------------------

    \53\ See Additional Methods, Determinations, and Analyses to 
Modify Air Quality Data Beyond Exceptional Events (EPA, Apr. 4, 
2019) (the ``Additional Methods Guidance,'' available at https://www.epa.gov/sites/production/files/2019-04/documents/clarification_memo_on_data_modification_methods.pdf).
    \54\ 40 CFR part 51, appendix W.
---------------------------------------------------------------------------

    Table 4 below details the atypical, potentially wildfire-influenced 
values recorded at the Spanish Fork monitor, with the specific date the 
monitor was impacted and what the potential source could be.

  Table 4--2018 Atypical Event Values Excluded From the Baseline Design
                    Value at the Spanish Fork Monitor
------------------------------------------------------------------------
                                     Value,         Potential wildfire
              Date                [micro]g/m\3\          sources
------------------------------------------------------------------------
8/7/2018.......................            37.8  Coal Hollow.
8/9/2020.......................            50.8  Coal Hollow and other
                                                  western state(s)
                                                  fire(s).
8/10/2018......................            68.8  Coal Hollow and other
                                                  western state(s)
                                                  fire(s).
8/11/2018......................            49.6  Coal Hollow and other
                                                  western state(s)
                                                  fire(s).
8/13/2018......................            58.1  Coal Hollow and other
                                                  western state(s)
                                                  fire(s).
9/14/2018......................            71.5  Pole Creek and Bald
                                                  Mountain.
9/15/2018......................            42.6  Pole Creek and Bald
                                                  Mountain.
9/17/2018......................            74.5  Pole Creek and Bald
                                                  Mountain.
9/18/2018......................            57.7  Pole Creek and Bald
                                                  Mountain.
9/19/2020......................            76.3  Pole Creek and Bald
                                                  Mountain.
9/21/2018......................            39.3  Pole Creek and Bald
                                                  Mountain.
------------------------------------------------------------------------

    UDAQ worked with the EPA to determine whether these atypical values 
could be excluded under the approach described in the Additional 
Methods Guidance, and based on the specific modeling analysis conducted 
in accordance with EPA's Air Quality Models Guideline. We have reviewed 
historical data for the area and the HYSPLIT ``back trajectory 
analysis'' \55\ in which the State presented an analysis of the 
direction and sources of air pollution at the receptor site.\56\ Based 
on our review, and considering the provisions of Utah SIP Section 
IX.A.27.c.1.d., the EPA agrees with UDAQ's assessment that the atypical 
baseline design value of 35.4 [micro]g/m\3\ was exacerbated by local 
wildfire emissions, and the atypical monitoring data listing in Table 4 
above should be removed, which would set the BDV for modeling projected 
design values at 28.4 [micro]g/m\3\. This determination is only for the 
Spanish Fork monitor in the Provo 2006 24-hour PM2.5 NAA; no 
other monitor in the Provo PM2.5 NAA or the Salt Lake City 
PM2.5 NAA was affected by the local wildfires. Additionally, 
this determination is not an official EPA concurrence based on the 
Exceptional Events Rule. The atypical data discussed in Table 4 were 
fully considered in evaluating whether the area had attained the NAAQS, 
and were only excluded to provide a more accurate modeled projected 
design value--that is, the FDV--for the Spanish Fork monitor.
---------------------------------------------------------------------------

    \55\ The HYSPLIT model is a complete system for computing simple 
air parcel trajectories, as well as complex transport, dispersion, 
chemical transformation, and deposition simulations. A common 
application of this model is a back trajectory analysis to determine 
the origin of air masses and establish source-receptor 
relationships. Detailed information on the HYSPLIT model can be 
found at: https://www.arl.noaa.gov/hysplit/hysplit/.
    \56\ See ``2018 Wildfire Atypical Event Report'' within the Utah 
TSD (presenting HYSPLIT back trajectory analysis); the AQS report 
containing the historical data can be found in our docket.
---------------------------------------------------------------------------

    The modeled FDV is used as a part of the maintenance plan 
demonstration to show that the NAAs will maintain the NAAQS at a future 
date. In making future-year projections of PM2.5 
concentrations and attainment status for this purpose, the output from 
the CAMx model for the future years is not considered the final answer. 
That is, the model future year results are not used in an absolute 
sense, but in a relative sense to correct for model errors and bias. 
UDAQ performed model simulations for the 2017 baseline emissions and 
for the projected future year emissions, and the fractional change was 
calculated in the future year model relative to the baseline year model 
for the concentrations of each PM2.5 species.\57\ These 
fractional changes are called the model Relative Response Factor (RRF). 
The RRF approach is based on the assumption that, while the model may 
have errors in predicting absolute concentrations, the model is 
reliable for predicting the relative changes in PM2.5 
concentration as emissions change in the future. An RRF greater than 
one indicates that the model predicted PM2.5 is greater in 
the future year than in the 2017 base year, and 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 
EPA guidance \58\ and in the maintenance plans and TSD submitted by 
UDAQ.) The model RRF for each PM2.5 species is multiplied by 
the 2017 BDV species concentrations to estimate the FDV for each 
species. The FDVs are compared to the NAAQs to determine whether 
attainment is predicted at each monitoring location. Table 5 below 
provides FDV results for the Provo and Salt Lake City monitoring sites, 
projection years and shows that no FDV exceeds the NAAQS. Therefore, 
continued attainment is demonstrated in the Provo and Salt Lake City 
NAAs.
---------------------------------------------------------------------------

    \57\ PM2.5 species includes nitrate (NO3), sulfate 
(SO4), ammonium (NH4), organic carbon (OC), elemental carbon (EC), 
chloride (Cl), sodium (Na), crustal material (CM), and other species 
(other mass). Additional detail can be found at figures IX.A.27.13 
and IX.A.36.13 for the Provo and Salt Lake City NAAs, respectively.
    \58\ Modeling Guidance for Demonstrating Air Quality Goals for 
Ozone, PM2.5, and Regional Haze (EPA, Nov. 2018).

[[Page 71040]]



            Table 5--Baseline Design Value, Relative Response Factors, and Future Design Values for all Monitors and Future Projection Years
                                        [Units of design values are [micro]g/m\3\, while RRFs are dimensionless]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                NAA                        Monitor           AQS site      2016-2018 BDV     2026 RRF        2026 FDV        2035 RRF        2035 FDV
--------------------------------------------------------------------------------------------------------------------------------------------------------
Provo.............................  Lindon..............     49-049-4001            31.1            0.94            29.3            0.95          * 29.5
                                    Spanish Fork........     49-049-5010         ** 28.4               1            28.4               1          * 28.4
Salt Lake City....................  Brigham City........     49-003-0003            32.4            0.85            27.5               1        *** 27.5
                                    Bountiful...........     49-011-0004            28.5            0.99            28.1               1        *** 28.2
                                    Hawthorne...........     49-035-3006            33.4            0.95            31.8               1        *** 32.1
                                    Rose Park...........     49-035-3010            34.9            0.96            33.5               1        *** 33.6
                                    Ogden 2.............     49-057-0002            30.2            0.95            28.8               1        *** 28.9
                                    Erda ****...........     49-045-0004            25.5            0.90            23.0               1        *** 23.1
--------------------------------------------------------------------------------------------------------------------------------------------------------
* This value includes additional emissions added to the MAG MVEB from the safety margin. The safety margin is discussed further in Section II.D.2 below.
** This value excludes data from atypical events discussed above.
*** These values include additional emissions added to the WFRC MVEB from the safety margin. The safety margin is discussed further in Section II.D.2
  below.
**** Erda site uses 2016 speciation data instead of 2011 like the other Salt Lake City NAA monitors because Erda was a new site starting in 2016.

    As explained in 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 equivalent reduction measures are adopted. Emission 
reductions from source shutdowns can be considered permanent and 
enforceable, to the extent that those shutdowns have been reflected in 
the SIP and all applicable permits have been modified accordingly.
    For a maintenance demonstration, permanent and enforceable measures 
must be implemented and acted on before the EPA may act on the 
maintenance plan or redesignation request.\59\ Therefore, the EPA is 
taking concurrent action on these remaining attainment-related portions 
of the Moderate and Serious 2006 24-hour PM2.5 SIPs for the 
Provo and Salt Lake City NAAs. Our proposed approval of these remaining 
attainment-related portions of the Moderate and Serious 2006 24-hour 
PM2.5 Salt Lake City and Provo SIPs for area sources rules, 
mobile source controls, and stationary source emission limits in Utah's 
Part H section in their SIP to control direct PM2.5 and 
PM2.5 precursors is discussed in Section II.B.3 above. 
Additionally, the BACM/BACT analysis for area source rules, on-road 
mobile sources, off-road mobile sources, and stationary sources is 
discussed in Section II.B.3 above and in our TSD.
---------------------------------------------------------------------------

    \59\ See Calcagni Memorandum at 4.
---------------------------------------------------------------------------

    Based on the information described above and in our TSD, the EPA 
proposes to find that Utah has adequately demonstrated that the Provo 
and Salt Lake City areas 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, a 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. For verification, the maintenance plans should contain provisions 
for continued operation of air quality monitors. 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 
continuing to maintain an ambient monitoring network for 
PM2.5 in the Provo and Salt Lake City areas, in accordance 
with 40 CFR part 58 and the Utah SIP.
d. Verification of Continued Attainment
    Utah's maintenance plan submittal for the Provo and Salt Lake City 
areas must indicate how the State will track the progress of the 
maintenance plans. 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.27.c.(7) and Section 
IX.A.36.c.(7) of the Provo and Salt Lake City maintenance plans, 
respectively, 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 whether additional and/or re-
sited monitors are necessary, and whether mobile and stationary source 
emission projections are on target.
e. Contingency Plan
    Section 175A(d) of the Act requires that a maintenance plan include 
contingency provisions, as necessary, to promptly correct any violation 
of the NAAQS that occurs after redesignation of the area. For the 
maintenance plans 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 prior to 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.27.c.(8) and Section IX.A.36.c.(8), of 
the Provo and Salt Lake City maintenance plans, respectively, 
triggering the contingency plan does not automatically require a 
revision to the SIP, nor does it necessarily mean the area will be 
redesignated once again to nonattainment. Instead, a state will 
normally have an appropriate timeframe to correct the potential 
violation with

[[Page 71041]]

implementing one or more adopted contingency measures. If violations 
continue to occur, additional contingency measures will be adopted 
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, a state will identify a means 
of corrective action within six months after a potential violation. The 
state 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 Provo maintenance plan list of contingency measures consists 
of:
    (1) 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. Residential wood combustion represents a large emissions 
inventory source category at 43.6% of direct PM2.5 emissions 
in the 2017 county-wide inventory;
    (2) Measures to address fugitive dust from area sources. Fugitive 
dust represents 28.1% of direct PM2.5 emissions in the 2017 
county-wide inventory; and
    (3) Additional measures to address other PM2.5 sources 
identified in the emissions inventory, such as on-road vehicles, non-
road vehicles and engines, and industrial sources.
    The Salt Lake City maintenance plan list of contingency measures 
consists of:
    (1) 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. Residential wood combustion represents a large emissions 
inventory source category at 35.4% of direct PM2.5 emissions 
in the 2017 county-wide inventory;
    (2) Measures to address fugitive dust from area sources. Fugitive 
dust represents 31.2% of direct PM2.5 emissions in the 2017 
county-wide inventory; and
    (3) Additional measures to address other PM2.5 sources 
identified in the emissions inventory, such as on-road vehicles, non-
road vehicles and engines, and industrial sources.
    Based on the above, we propose to find that the contingency 
measures provided in the Provo and Salt Lake City 2006 24-hour 
PM2.5 maintenance plans 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 plans eight years after the 
redesignation of the Provo and Salt Lake City areas to attainment for 
the 2006 24-hour PM2.5 NAAQS. This revision is to provide 
for maintenance of the NAAQS for an additional ten years following the 
first ten-year period. In the Provo and Salt Lake City maintenance 
plans, 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) requires 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, the state must have met all 
requirements that applied to the subject area prior to, or at the time 
of, submitting a complete redesignation request. In our evaluation of a 
redesignation request, we do not 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 nonattainment 
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, Utah submitted an Infrastructure SIP 
to the EPA demonstrating compliance with the requirements of section 
110 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, 
Utah must have fulfilled the applicable requirements of part D. Subpart 
1 of part D establishes the general requirements applicable to all 
NAAs, while subpart 4 of part D establishes specific requirements 
applicable to PM10/PM2.5 NAAs. The 
PM2.5 SIP Requirements Rule provides that the applicable 
requirements of CAA section 172 are subsections 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). We have interpreted 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, Utah 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), 189(a), and 189(b) regarding 
attainment of the 2006 24-hour PM2.5 NAAQS, have been 
satisfied through our 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) actions approving portions of the Moderate 2006 24-hour 
PM2.5 Provo and Salt Lake City SIPs. On April 10, 2019 (84 
FR 14267) and September 27, 2019 (84 FR 51055), the EPA approved CDDs 
for the Provo and Salt Lake City NAAs, respectively. As specified at 40 
CFR 51.1015(a) in the PM2.5 SIP Requirements Rule, upon this 
determination by the EPA that the Moderate PM2.5 NAAs have 
attained the 2006 24-hour PM2.5 NAAQS, the requirements for 
Utah to submit an attainment demonstration, provisions demonstrating 
timely implementation of RACM/RACT, a RFP plan, quantitative milestones 
and quantitative milestone reports, and contingency measures were 
suspended. Additionally, under 40 CFR 51.1015(b), upon this 
determination from the EPA that the Serious PM2.5 NAAs have 
attained the 2006 24-hour PM2.5 NAAQS, the requirements for 
the State to submit an attainment demonstration, RFP plan, quantitative 
milestones and quantitative milestone reports, and contingency measures 
for the areas were suspended. However, the CDDs for the Provo and Salt 
Lake City NAAs did not suspend requirements that were independent of 
attainment: BACM/BACT, NNSR, and base-year emissions inventories. The 
BACM/BACT analysis, including any accompanying rule or limit revision, 
is discussed in Section II.B.3 above and completes this element.
    We approved the requirements of the part D NSR permit program for 
Utah on July 25, 2019 (84 FR 35831), which is briefly discussed above 
in Section II.B.2. Once the Provo and Salt Lake City areas are 
redesignated to attainment, the prevention of significant deterioration

[[Page 71042]]

(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 they will apply in the Provo and Salt Lake City areas 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 Provo and Salt Lake City areas upon redesignation of the areas to 
attainment.
    Additionally, the remaining element that is independent of 
attainment is the base-year emissions inventories for the Provo and 
Salt Lake City, which is being acted on in Section II.C.4.a above and 
is briefly discussed in Section II.B.1 above.

D. Have transportation conformity requirements been met?

1. Requirements for Transportation Conformity and Motor Vehicle 
Emissions Budgets (MVEBs)
    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 on 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.\60\
---------------------------------------------------------------------------

    \60\ See 58 FR 62193-62196.
---------------------------------------------------------------------------

    A 2006 24-hour 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. For both the Provo and Salt Lake City 2006 24-hour 
PM2.5 maintenance plan SIP revisions, the UDAQ also 
identified VOCs as a precursor to the formation of PM2.5 in 
both areas. 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.\61\ 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 has concurred with the State's analysis as to re-entrained road 
dust.\62\
---------------------------------------------------------------------------

    \61\ 40 CFR 93.102(b) and 93.122(f); see also conformity rule 
preamble at 69 FR 40004, 40031-40036 (July 1, 2004).
    \62\ Email from Tim Russ, EPA, to Bill Reiss, UDAQ, subject 
``PM2.5 Re-entrained Road Dust--Utah Request for Deletion 
from PM2.5 Motor Vehicle Emissions Budget (MVEB): EPA 
Concurrence'' (July 20, 2011).
---------------------------------------------------------------------------

    For maintenance plans that do not identify MVEBs for any other year 
than the last year of the 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.\63\
---------------------------------------------------------------------------

    \63\ 40 CFR 93.118(b)(2)(i).
---------------------------------------------------------------------------

2. MVEBs Identified in the Provo Maintenance Plan SIP
    Utah's Provo 2006 24-hour PM2.5 maintenance plan SIP 
revision specified the maximum mobile source emissions of 
PM2.5, NOX and VOC allowed in 2035, the final 
maintenance year. These mobile source emissions were then initially 
identified by the State as the maintenance plan's MVEBs. However, 
through sensitivity dispersion modeling, the state was able to 
demonstrate that for 2035, additional mobile source emissions could be 
included such that the Provo area could continue to demonstrate 
maintenance. These additional direct PM2.5, NOX, 
and VOC mobile source emissions were then identified as a ``safety 
margin'' \64\ and were 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 ``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 submitted by UDAQ. As presented in Table IX.A.27.11 of the 
maintenance plan, the final 2035 MVEBs were 1.5 tpd direct 
PM2.5, 6.5 tpd NOX, and 7.0 tpd VOCs.
---------------------------------------------------------------------------

    \64\ 40 CFR 93.101.
---------------------------------------------------------------------------

3. MVEB Trading for Demonstrating Transportation Conformity in the 
Provo 2006 24-Hour PM2.5 Maintenance Area
    The EPA's transportation conformity regulations allow trading 
between the direct PM2.5 and NOX and VOC 
precursor MVEBs where the SIP establishes an appropriate mechanism.\65\ 
The State of Utah has established an MVEB trading mechanism to allow 
future increases in on-road mobile sources direct PM2.5 
emissions to be offset by future decreases in NOX precursor 
emissions or future decreases in VOC precursor emissions from on-road 
mobile sources. The basis for the trading mechanism is each maintenance 
plan's dispersion modeling demonstration for the year 2035, which 
established the relative contribution of the NOX and VOC 
precursor pollutants. These ratios were developed using data from the 
air quality maintenance plan's dispersion modeling. Section 4(a)(ii) of 
the maintenance plan and Section 6.a. (Trading Ratio) of the 
maintenance plan's TSD provide the following modeling-derived trading 
ratios: 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 5.8 to 1, and future 
increases in on-road mobile sources' direct PM2.5 emissions 
may be offset with future decreases in VOC emissions from on-road 
mobile sources at a VOC to PM2.5 ratio of 27.9 to 1.
---------------------------------------------------------------------------

    \65\ 40 CFR 93.124(b).
---------------------------------------------------------------------------

    The maintenance plan also notes that this trading mechanism will 
only be used by the Mountainland Association of Governments (MAG), the 
MPO for Utah County, 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 and VOC

[[Page 71043]]

budgets, the NOX and VOC emission reductions available to 
supplement the direct PM2.5 MVEB will only be those 
remaining after the 2035 NOX and VOC MVEBs have been met. 
The maintenance plan further articulates that clear documentation of 
the calculations used in the MVEB trading is to be included in the 
conformity determination analysis as prepared by the MAG MPO.
4. MVEBs Identified in the Salt Lake City Maintenance Plan SIP
    Utah's Salt Lake City 2006 24-hour PM2.5 maintenance 
plan SIP revision 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 then 
initially identified by the State as the maintenance plan's MVEBs. 
However, as with the Provo NAA, through sensitivity dispersion modeling 
the State was able to demonstrate that for 2035, additional mobile 
sources emissions could be included such that the Salt Lake City area 
could continue to demonstrate maintenance. These additional direct 
PM2.5, NOX, and VOC mobile source emissions were 
then identified as a ``safety margin'' \66\ 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 as allowed by 40 CFR 93.124(a). The derivation of the MVEBs, with 
``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 submitted by UDAQ. As presented in Table 
IX.A.36.11 of the maintenance plan, the final 2035 MVEBs were 1.38 tpd 
direct PM2.5, 21.63 tpd NOX, and 20.57 tpd VOCs.
---------------------------------------------------------------------------

    \66\ 40 CFR 93.101.
---------------------------------------------------------------------------

5. MVEB Trading for of Demonstrating Transportation Conformity, in the 
Salt Lake City 2006 24-Hour PM2.5 Maintenance Area
    As discussed above, the EPA transportation conformity regulations 
allow trading between direct PM2.5 and NOX and 
VOC precursor MVEBs, if the SIP establishes an appropriate 
mechanism.\67\
---------------------------------------------------------------------------

    \67\ 40 CFR 93.124(b).
---------------------------------------------------------------------------

    The State has established an 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 or future decreases in VOC precursor emissions from on-road 
mobile sources. The basis for the trading mechanism is the maintenance 
plan's dispersion modeling demonstration for the year 2035, which 
established the relative contribution of the NOX and VOC 
precursor pollutants. These ratios were developed from data from the 
air quality maintenance plan's dispersion modeling. Section 4(a)(ii) of 
the maintenance plan and Section 6.a. (Trading Ratio) of the 
maintenance plan's TSD provide the following modeling-derived trading 
ratios: 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 6.3 to 1, and future 
increases in on-road mobile sources' direct PM2.5 emissions 
may be offset with future decreases in VOC emissions from on-road 
mobile sources at a VOC to PM2.5 ratio of 20.9 to 1.
    The maintenance plan also notes that this trading mechanism will 
only be used by the Wasatch Front Regional Council (WFRC), the MPO for 
Salt Lake City 2006 24-hour PM2.5 maintenance area counties, 
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 and VOC budgets, the NOX and VOC 
emission reductions available to supplement the direct PM2.5 
MVEB shall only be those remaining after the 2035 NOX and 
VOC MVEBs have been met. The maintenance plan further articulates that 
clear documentation of the calculations used in the MVEB trading are to 
be included in the conformity determination analysis as prepared by the 
WFRC MPO.
6. EPA's Evaluation of Mobile Source Emissions and MVEBs
    The EPA has evaluated the Provo and Salt Lake City 2006 24-hour 
PM2.5 maintenance plan's emission inventories and 
maintenance demonstration modeling as described above, and have 
determined that the direct PM2.5, NOX, and VOC 
MVEBs have been appropriately derived for each maintenance plan and are 
acceptable. We have also evaluated the description and derivation of 
the MVEB NOX and VOC trading mechanisms, the supporting 
modeling data maintenance demonstration, and the TSDs submitted by 
UDAQ. We find the trading mechanisms acceptable. Therefore, we are 
proposing to approve the Provo 2006 24-hour PM2.5 
maintenance plan's 2035 MVEBs of direct PM2.5 of 1.5 tpd, 
NOX of 6.5 tpd, and VOC of 7.0 tpd. We are also proposing to 
approve the Salt Lake City 2006 24-hour PM2.5 maintenance 
plan's 2035 MVEBs of direct PM2.5 of 1.38 tpd, 
NOX of 21.63 tpd, and VOC of 20.57 tpd. In addition, we are 
also proposing to approve the NOX/VOC-to-direct 
PM2.5 MVEB trading mechanisms as described above and 
documented in Section 4(a)(ii) of each respective 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 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.\68\ Our completeness 
criteria for SIP submittals are set out 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.
---------------------------------------------------------------------------

    \68\ CAA section 110(k)(1); 57 FR 13565.
---------------------------------------------------------------------------

    On July 11, 2012, the UAQB approved for public comment a new Rule 
R307-208 (Outdoor Wood Boiler Prohibition), with a comment period from 
August 1 to August 31, 2012, and a public hearing on August 15, 2012. 
UDAQ received comments from industry, environmental groups, and 
citizens, and based on these comments, UDAQ made significant changes to 
the rule, and on November 7, 2012, requested the UAQB proposed the 
revised rule for a second comment period. This comment period was held 
from December 1 through 31, 2012, and no public hearing was requested. 
Comments were submitted by industry during this second comment period 
and UDAQ made significant changes to the rule where another comment 
period was required. On February 6, 2013, the UAQB approved these 
revisions for a third comment period from March 1 through April 1, 
2013. The UAQB approved, and the rule became effective

[[Page 71044]]

on April 10, 2013 and UDAQ submitted this new rule to the EPA on July 
21, 2020.
    On September 3, 2014, the UAQB approved the Salt Lake City and 
Provo Moderate 2006 24-hour PM2.5 SIP revisions for public 
comment, which took place from October 1 through October 31, 2014, with 
a public hearing on October 20, 2014. Comments were submitted by 
industry, environmental groups, and the EPA. UDAQ responded to all 
comments and made insignificant changes that did not warrant a second 
comment period. The UAQB approved the 2006 24-hour PM2.5 
Moderate SIP for submission to the EPA on December 3, 2014, and the SIP 
became effective on December 4, 2014. UDAQ submitted the Moderate 2006 
24-hour PM2.5 SIPs on December 16, 2014.
    On May 3, 2017, the UAQB approved the new rule R307-230 
(NOX Emission Limits for Natural Gas-Fired Water Heaters) 
for public comment from June 1, 2017 to July 3, 2017; no public hearing 
was requested. No comments were received, and the rule was approved by 
the UAQB on August 2, 2017, and it became effective on August 3, 2017. 
UDAQ submitted the rule to the EPA on July 21, 2020.
    On September 7, 2016, the UAQB approved Utah SIP Section IX.H.13 
(Source-Specific Emission Limitations in Provo--UT PM2.5 
Nonattainment Area) for the PM2.5 SIPs for public comment, 
which was accepted from October 1 through October 31, 2016, with a 
public hearing on October 26, 2016. Comments were submitted by industry 
and environmental groups. UDAQ responded to all comments and made 
insignificant changes that did not warrant a second comment period. The 
UAQB approved Utah SIP Section IX.H.13 for submission to the EPA on 
December 7, 2016, and the rule became effective on December 8, 2016. 
UDAQ submitted the revisions on January 19, 2017.
    On June 7, 2017, the UAQB approved a new rule, R307-304 (Solvent 
Cleaning) for the PM2.5 SIPs for public comment, which 
extended from July 1 through August 15, 2017, with a public hearing on 
July 27, 2017. Comments were submitted by industry and environmental 
groups. UDAQ responded to all comments and made insignificant changes 
that did not warrant a second comment period. The UAQB approved the new 
rule, R307-304 (Solvent Cleaning)] for submission to the EPA on 
December 6, 2017, and the rule became effective on December 6, 2017. 
UDAQ submitted the new rule on May 21, 2020.
    On June 7, 2017, the UAQB approved revisions to the following area 
source rules: R307-335 (Degreasing); R307-343 (Wood Furniture 
Manufacturing Operations); R307-344 (Paper, Film, and Foil Coatings); 
R307-345 (Fabric and Vinyl Coatings); R307-346 (Metal Furniture Surface 
Coatings); R307-347 (Large Appliance Surface Coatings); R307-348 
(Magnet Wire Coatings); R307-349 (Flat Wood Panel Coatings); R307-350 
(Miscellaneous Metal Parts and Products Coatings); R307-351 (Graphic 
Arts); R307-352 (Metal Container, Closure, and Coil Coatings); R307-353 
(Plastic Parts Coatings); and R307-354 (Automotive Refinishing 
Coatings). Public comment was accepted from July 1 through August 15, 
2017, with a public hearing on July 27, 2017. Comments were submitted 
by industry and environmental groups. UDAQ responded to all comments 
and made insignificant changes that did not warrant a second comment 
period. The UAQB approved these rules, except R307-350, R307-353, and 
R307-355, to be submitted to the EPA on October 4, 2017. Additionally, 
on October 4, 2017, the UAQB requested revisions to R307-350, R307-353, 
and R307-355. UDAQ presented these revisions to the UAQB on December 6, 
2017, which required a second comment period, from January 1 through 
January 31, 2018. Industry submitted comments and UDAQ provided 
responses within the submittal and made insignificant changes to these 
rules during the second comment period. R307-335 became effective on 
October 29, 2017, and R307-343, R307-344, R307-345, R307-346, R307-347, 
R307-348, R307-349, R307-350, R307-351, R307-352, R307-353, R307-354, 
and R307-355 became effective on December 6, 2017. UDAQ submitted these 
rules to the EPA on April 19, 2018.
    On June 6, 2018, the UAQB approved the revisions to Utah SIP 
Sections IX.H.11 and 12, with the accompanying BACM/BACT analysis. 
Additionally, the BACM/BACT analyses for on-road mobile, off-road 
mobile, and area source rules were approved for public comment. The 
comment period was held from July 1 to August 15, 2018, and no public 
hearing was requested. Comments were received by industry, 
environmental groups and the EPA. UDAQ responded to these comments and 
held two follow-up comment periods. The first was held from October 1 
through October 31, 2018. This comment period was for the Salt Lake 
City Serious 2006 24-hour PM2.5 SIP, including the potential 
for UDAQ to complete a major stationary source precursor demonstration 
for the SIP. The second follow-up comment period was held from November 
1 through November 30, 2018. This comment period was for significant 
revisions to Utah SIP Sections IX.H.11, 12, and BACM/BACT 
demonstration. Comments were submitted by industry, environmental 
groups, and the EPA in these second-round comment periods. UDAQ 
responded to all the comments and took the final SIP package to the 
January 2, 2019 UAQB meeting which approved the SIP elements to be 
submitted to the EPA. The SIP became effective on January 3, 2019 and 
was submitted to the EPA on February 15, 2019.
    On May 15, 2018, UDAQ published a Notice of Public Comment Period 
for the Provo Serious 2006 24-hour PM2.5 SIP elements that 
were not suspended with the April 10, 2019 CDD (84 FR 14267). These 
elements included: Base-year emissions inventory and provisions to 
ensure BACM/BACT for area sources, major stationary sources, on-road 
mobile sources, and off-road mobile sources. These documents did not 
need to go through the UAQB, because no portion of the Utah SIP was 
revised; UDAQ completed a detailed analysis and supporting inventory 
for what is currently within the Utah SIP for the Provo 2006 24-hour 
PM2.5 NAA. The comment period was held from May 16, 2018 to 
June 16, 2018, and a public hearing was not requested. UDAQ received 
comments from industry, environmental groups, and the EPA. UDAQ 
responded to all submitted comments and made only insignificant 
revisions that did not warrant a second comment period; therefore, UDAQ 
submitted these remaining Provo Serious 2006 24-hour PM2.5 
SIP elements to the EPA on February 4, 2019.
    On September 4, 2019, the UAQB proposed for public comment the 
Provo and Salt Lake City maintenance plans and redesignation request 
and revisions to R307-110-10. The public comment period was held from 
October 1 to October 31, 2019. UDAQ received comments from industry and 
citizens, and no public hearing was requested. The comments were 
minimal and did not prompt UDAQ to substantively revise any documents. 
UDAQ made minor revisions to the plan once the data and modeling were 
verified. On December 4, 2019, the UAQB adopted R307-110-10 and the 
Provo and Salt Lake City maintenance plans/redesignation requests, 
effective December 5, 2019. UDAQ submitted these revisions and the TSD 
to the EPA on January 13, 2020.

[[Page 71045]]

    On November 20, 2019, the UAQB proposed amendments to Utah SIP 
Section X, Vehicle Inspection and Maintenance Program, Parts B and E; 
R307-110-32; and R307-110-35. The comment period was held from January 
1 to 31, 2020. A public hearing was held on Monday February 3, 2020; 
however, due to severe weather, a second public hearing was held on 
Wednesday February 5, 2020. No comments were received, and no one 
attended either public hearing. On March 4, 2020, the UAQB adopted 
revisions to R307-110-32; R307-110-35 and to Utah SIP Section X, 
Vehicle Inspection and Maintenance Program, Parts B and E. These 
revisions became effective on March 5, 2020, and UDAQ submitted these 
revisions to the EPA on May 21, 2020.
    On October 9, 2020, UDAQ submitted a draft SIP revision to the Utah 
SIP Section IX.H.12.i.i.C (Kennecott Power Plant), which will remove 
the startup/shutdown emission limits from this Utah SIP section, to the 
EPA for parallel processing. The comment period at the State level 
began October 1 and will end November 3, 2020, with a public hearing 
being held on November 3, 2020. UDAQ requested this parallel processing 
so as not to delay action on the 2006 24-hour PM2.5 
redesignations for the Salt Lake City and Provo NAAs. UDAQ is planning 
on submitting this SIP revision early in January 2021. After the State 
formally submits these revisions, the EPA will evaluate the submittal 
for any changes between the proposed and final versions. As discussed 
above in Section I.E, the EPA will determine if any changes to the 
draft submission would warrant another proposed rule, or if on the 
other hand the agency may proceed with a final action. This formal 
submission from the State of Utah will accompany either the final rule 
or the new proposed rule under this docket number.

III. Proposed Action

    We are proposing to redesignate the Salt Lake City and Provo 2006 
24-hour PM2.5 NAAs, and to approve multiple related SIP 
submissions. We are proposing to approve the Governor of Utah's 
submittal of January 13, 2020, containing revisions to R307-110-10, and 
the Provo and Salt Lake City 2006 24-hour PM2.5 maintenance 
plans and redesignation requests. We are also proposing to approve the 
Governor of Utah's submittal of May 21, 2020, with revisions to R307-
110-32, R307-110-35, Utah SIP Section X.B., and Utah SIP Section X.E, 
which are the I/M programs for Davis and Weber Counties. We are 
proposing to approve both maintenance plans' 2035 MVEBs. In addition, 
we are proposing to approve the NOX and VOC to direct 
PM2.5 MVEB trading mechanisms in each maintenance plan. We 
are proposing approval of these submissions because UDAQ has adequately 
addressed all of the requirements of the Act for the SIP revisions and 
the redesignation to attainment applicable to the Provo and Salt Lake 
City 2006 24-hour PM2.5 NAAs. We are using 2017-2019 ambient 
air quality data from the Provo and Salt Lake City NAAs as the basis 
for our decision. Upon the effective date of a subsequent final action, 
the designation status of the Provo and Salt Lake City areas under 40 
CFR part 81 will be revised to attainment.
    Additionally, we are proposing to approve SIP revisions submitted 
on January 19, 2017 (Utah SIP Section IX.H.13), and February 15, 2019 
(Utah SIP Section IX.H.11 and 12). Additionally, we are proposing to 
approve, through parallel processing, Utah's draft October 9, 2020 
submission removing the startup/shutdown emission limits for the 
Kennecott Power Plant found in Utah SIP Section IX.H.12.i.i.C, and the 
accompanying R307-110-17.
    The EPA is proposing to approve the Utah UAC section R307-200 and 
R307-300 Series revisions and new rules submitted by UDAQ on April 19, 
2018, May 21, 2020 and July 21, 2020, which are intended to strengthen 
the SIP and to serve as BACM for certain area sources for the Utah 
PM2.5 SIP. These rules are R307-208, R307-230, R307-304, 
R307-335, R307-343, R307-344, R307-345, R307-346, R307-347, R307-348, 
R307-349, R307-350, R307-351, R307-352, R307-353, R307-354 and R307-
355. Additionally, the EPA is proposing to approve the area sources, 
major stationary sources, on-road mobile sources, and non-road mobile 
sources BACM/BACT analyses for the Provo and Salt Lake City 2006 24-
hour PM2.5 NAAs that were submitted on February 4, 2019 and 
February 15, 2019.

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; R307-110-17; R307-
110-32; R307-110-35; R307-208; R307-230; R307-304; R307-335; R307-343; 
R307-344; R307-345; R307-346; R307-347; R307-348; R307-349; R307-350; 
R307-351; R307-352; R307-353; R307-354; R307-355; Utah SIP Section 
X.B.; Utah SIP Section X.E.; Utah SIP Section IX.H.11, 12, and 13; Utah 
SIP Section IX.A.27 (Provo 2006 24-hour PM2.5 Maintenance 
Plan); Utah SIP Section IX.A.36 (Salt Lake City 2006 24-hour 
PM2.5 Maintenance Plan); and the redesignation requests for 
the Provo and Salt Lake City 2006 24-hour PM2.5 NAAs 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 
FUTHER 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);

[[Page 71046]]

     Is not subject to requirements of section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the CAA; and
     Does not provide EPA with the discretionary authority to 
address, as appropriate, disproportionate human health or environmental 
effects, using practicable and legally permissible methods, under 
Executive Order 12898 (59 FR 7629, February 16, 1994).
    In addition, the SIP is not approved to apply on any Indian 
reservation land or in any other area where EPA or an Indian tribe has 
demonstrated that a tribe has jurisdiction. In those areas of Indian 
country, 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: October 29, 2020.
Gregory Sopkin,
Regional Administrator, EPA Region 8.
[FR Doc. 2020-24444 Filed 11-5-20; 8:45 am]
BILLING CODE 6560-50-P