[Federal Register Volume 89, Number 70 (Wednesday, April 10, 2024)]
[Proposed Rules]
[Pages 25216-25223]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-07584]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R08-OAR-2023-0441; FRL-11837-01-R8]
Air Plan Approval; Colorado; 2017 Base Year Inventory and
Emission Statement Rule Marginal Nonattainment Requirements, Revisions
to Regulation 3
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
approve state implementation plan (SIP) revisions submitted by the
State of Colorado to meet certain Clean Air Act (CAA) requirements
related to the Denver Metro/North Front Range (DMNFR) area's
classification as Marginal nonattainment for the 2015 8-hour ozone
national ambient air quality standards (NAAQS). The revisions contain a
base year emissions inventory for the nonattainment area and certify
that the State's existing Air Pollutant Emissions Notice (APEN) program
fulfills the CAA's emission statement rule requirement. The revisions
also include a new requirement for annual certification of APEN
reported emissions. Unrelated to Colorado's Marginal ozone
nonattainment obligations, EPA is also proposing to approve the State's
revisions to Regulation 3 concerning an update to the date of
incorporation by reference of global warming potentials used in the
computation of the carbon dioxide equivalent for comparing emissions
from various greenhouse gases (GHGs). EPA is taking this action
pursuant to the CAA.
DATES: Written comments must be received on or before May 10, 2024.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R08-
OAR-2023-0441, 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
[[Page 25217]]
electronically any information you consider to be Confidential Business
Information (CBI) or other information whose disclosure is restricted
by statute. Multimedia submissions (audio, video, etc.) must be
accompanied by a written comment. The written comment is considered the
official comment and should include discussion of all points you wish
to make. The EPA will generally not consider comments or comment
contents located outside of the primary submission (i.e., on the web,
cloud, or other file sharing system). For additional submission
methods, the full EPA public comment policy, information about CBI or
multimedia submissions, and general guidance on making effective
comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.
Docket: All documents in the docket are listed in the
www.regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available electronically in
www.regulations.gov. To reduce the risk of COVID-19 transmission, for
this action we do not plan to offer hard copy review of the docket.
Please email or call the person listed in the FOR FURTHER INFORMATION
CONTACT section if you need to make alternative arrangements for access
to the docket.
FOR FURTHER INFORMATION CONTACT: Matthew Lang, Air and Radiation
Division, EPA, Region 8, Mailcode 8ARD-IO, 1595 Wynkoop Street, Denver,
Colorado 80202-1129, (303) 312-6709, [email protected].
SUPPLEMENTARY INFORMATION: Throughout this document wherever ``we,''
``us,'' or ``our'' is used, we mean the EPA.
Table of Contents
I. Background
II. The EPA's Evaluation of Colorado's SIP Submittals
A. Base Year Emissions Inventory
1. Point Source Emissions
2. Nonpoint Source Emissions
3. On-Road Mobile Source Emissions
4. Nonroad Mobile Source Emissions
5. Oil and Gas Emissions
6. Biogenic Emissions
7. EPA's Evaluation of the Base Year Emissions Inventory
B. Certification of Existing Emission Statement Rule and
Addition of Annual Certification Requirement
C. Other Revisions to Regulation 3, Part A
1. Regulation 3, Part A, Sections I.B.10 and 1.B.44.b.(i)--Date
of Incorporation by Reference of Global Warming Potentials
2. Regulation 3, Part A, Section I.B.44.(b).(i)--Computation of
Mass of Carbon Dioxide Equivalent
III. Proposed Action
IV. Incorporation by Reference
V. Statutory and Executive Order Reviews
I. Background
EPA determined decades ago that ground-level ozone endangers public
health and welfare. Ground-level ozone forms when nitrogen oxides
(NOX) and volatile organic compounds (VOC) react in the
presence of sunlight. Referred to as ozone precursors, these two
pollutants are emitted by many types of pollution sources, including
motor vehicles, power plants, industrial facilities, and nonpoint \1\
sources. Scientific evidence indicates that adverse human health
effects occur following exposure to ozone. These effects are more
pronounced in children and adults with lung disease. Breathing air
containing ozone can reduce lung function and inflame airways, which
can increase respiratory symptoms and aggravate asthma or other lung
diseases. In 1979, in response to this scientific evidence, EPA
promulgated the first ozone NAAQS, the 0.12 parts per million (ppm) 1-
hour ozone NAAQS.\2\
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\1\ Nonpoint sources are also sometimes referred to as area
sources.
\2\ 44 FR 8202 (Feb. 8, 1979).
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EPA has strengthened the ozone NAAQS over the years. In 1997, EPA
promulgated a revised ozone NAAQS of 0.08 ppm, averaged over eight
hours, which it determined was more protective of public health than
the 1979 standard.\3\ In 2008, EPA revised the 8-hour ozone NAAQS from
0.08 to 0.075 ppm.\4\ In 2015, the Agency further strengthened the 8-
hour ozone NAAQS to 0.070 ppm.\5\
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\3\ 62 FR 38856 (July 18, 1997).
\4\ 73 FR 16436 (Mar. 27, 2008).
\5\ 80 FR 65292 (Oct. 26, 2015).
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The DMNFR area is in nonattainment status for both the 2008 and the
2015 ozone NAAQS. It is currently classified as a Severe nonattainment
area under the 2008 standard,\6\ which is not at issue in this
rulemaking. Effective August 3, 2018, EPA designated the DMNFR area as
Marginal nonattainment for the more stringent 2015 ozone NAAQS (2015
DMNFR Nonattainment Area).\7\ The 2015 DMNFR Nonattainment Area
includes Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas,
Jefferson, and Weld counties as well as a portion of Larimer County.\8\
While EPA has since reclassified the 2015 DMNFR Nonattainment Area as
Moderate for failing to attain the 2015 ozone NAAQS by the area's
Marginal attainment date,\9\ Colorado must still meet the CAA
requirements applicable to Marginal ozone nonattainment areas.
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\6\ 40 CFR 81.306; 87 FR 60926, 60933 (Oct. 7, 2022).
\7\ 83 FR 25776, 25792 (June 4, 2018).
\8\ As detailed in this proposed rule, EPA initially excluded
part of Weld County from the 2015 DMNFR Nonattainment Area, but, in
response to a court decision, subsequently expanded its air quality
designation to include all of Weld County.
\9\ 40 CFR 81.306; 87 FR 60897, 60916 (Oct. 7, 2022).
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This proposed rule addresses only the base year inventory and
emission statement rule requirements related to the Marginal
nonattainment classification, as described further below, including SIP
revisions to address EPA's revised designation incorporating all of
Weld County into the nonattainment area.\10\ Requirements stemming from
the DMNFR Nonattainment Area's Moderate nonattainment classification
for the 2015 ozone NAAQS and the Severe classification for the 2008
ozone NAAQS will be addressed in separate EPA rulemakings.
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\10\ See 86 FR 67864, 67869 (Nov. 30, 2021) (noting that states
affected by the revised air quality designations would ``work with
their respective EPA Regional office to submit any necessary
supplements or revisions to fulfill the Marginal area SIP revision
requirements associated with the nonattainment boundaries in this
final action as expeditiously as practicable'').
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The CAA and its implementing regulations--in particular, the 2015
ozone NAAQS SIP Requirements Rule,\11\ codified at 40 CFR part 51,
subpart CC--establish several requirements for ozone nonattainment
areas. Section 172(c)(3) of the CAA, which applies generally to states
with areas classified as nonattainment for any NAAQS, requires
submission of comprehensive, accurate, and current inventories of
actual emissions from all sources of relevant pollutants in Marginal
nonattainment areas.\12\ Specific to areas classified as Marginal ozone
nonattainment, section 182(a)(1) requires states to submit a base year
inventory of ozone precursors (NOX and VOC) within two years
of the nonattainment designation.\13\ Section 182(a)(3)(B) directs
states to implement an emission statement rule requiring certain
stationary sources to report their emissions of NOX and
VOC.\14\
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\11\ 83 FR 62998 (Dec. 6, 2018). The SIP Requirements Rule
established implementation requirements for the 2015 ozone NAAQS,
including requirements for base year emissions inventories.
\12\ 42 U.S.C. 7502(c)(3).
\13\ 42 U.S.C. 7511a(a)(1); 40 CFR 51.1315(a); 40 CFR 51.1300(p)
(defining ``base year inventory'').
\14\ 42 U.S.C. 7511a(a)(3)(B).
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Emissions inventories and emission statements provide data that
inform a variety of air quality planning tasks. States use emissions
inventories to establish baseline emissions levels, calculate emissions
reduction targets needed to attain the NAAQS, determine emissions
inputs for ozone air quality modeling analyses, and track emissions
over time to determine progress toward achieving air quality and
emissions reduction goals. EPA has issued guidance to assist states in
developing their emission inventories; states retain the discretion to
adopt approaches on a case-by-case basis that differ from that guidance
where appropriate.\15\ Emission statements provide important
information that states may use to develop emissions inventories for
air quality planning, to support permitting efforts, and to assist in
demonstrating source compliance.\16\
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\15\ U.S. EPA, ``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), 1 (2017 Emissions Inventory Guidance).
\16\ U.S. EPA, ``Draft Guidance on the Implementation of an
Emission Statement Program'' (July 1992), 1.
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On July 27, 2020, through the Colorado Department of Public Health
and Environment (CDPHE), Colorado submitted a SIP revision titled
``2015 Ozone National Ambient Air Quality Standard (NAAQS)--Denver
Metro/North Front Range Marginal Nonattainment Area Requirements''
(2020 SIP Submittal) to satisfy, in part, the emissions inventory
requirements under CAA sections 172(c)(3) and 182(a)(1) and the
emission statement requirement of CAA section 182(a)(3)(B).\17\
Colorado met the CAA's reasonable notice and public hearing
requirements \18\ for the 2020 SIP Submittal through notice in the
Denver Legal Post on May 23, 2020, and a public hearing on June 18,
2020.\19\ However, before EPA proposed action on the 2020 SIP
Submittal, the 2015 DMNFR Nonattainment Area boundary, and specifically
the partial nonattainment designation of Weld County, was remanded
without vacatur in Clean Wisconsin v. EPA, 964 F.3d 1145 (D.C. Cir.
2020). EPA then issued a revised designation to include the whole of
Weld County in the nonattainment area and noted that states should work
with their respective EPA regional office to submit any necessary
supplements or revisions to fulfill Marginal area SIP requirements.\20\
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\17\ 2020 SIP Submittal, ``01-Submittal Letter to EPA.'' The
letter is dated July 6, 2020, but the SIP was submitted to EPA on
July 27, 2020. The 2020 SIP Submittal was deemed complete by
operation of law six months after submission.
\18\ 42 U.S.C. 7410(a)(1), (l); 40 CFR 51.102.
\19\ 2020 SIP Submittal, ``03-Denver Post Legal Ad'' and ``04-
Meeting Agenda.''
\20\ 86 FR 67864, 67869. The revised designation was affirmed in
Board of County Commissioners of Weld County, Colorado v. EPA, 72
F.4th 284, 289-92 (D.C. Cir. 2023).
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In response, on June 26, 2023, CDPHE submitted a SIP revision
titled ``Ozone State Implementation Plan (SIP) and Associated
Regulations: Regulation Number 3, Regulation Number 7, Regulation
Number 21, Common Provisions, and Air Quality Standards, Designations,
and Emissions Budgets'' (2023 SIP Submittal).\21\ Among other
components,\22\ the 2023 SIP Submittal includes rule revisions to
address the outstanding Marginal area SIP requirements for the 2015
DMNFR Nonattainment Area, including an updated base year inventory
reflecting EPA's revised boundary designation of the 2015 DMNFR
Nonattainment Area. Colorado met the CAA's reasonable notice and public
hearing requirements through notice in the Denver Legal Post on
September 17, 2022, and a public hearing on December 13-16, 2022.\23\
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\21\ 2023 SIP Submittal, Document Set 1 of 7, ``00_Submittal
Letter to EPA_Ozone SIP.'' The letter is dated June 22, 2023, but
the SIP was submitted to EPA on June 26, 2023. EPA determined the
2023 SIP Submittal to be complete on September 7, 2023.
\22\ The 2023 SIP Submittal includes elements of Colorado's 2008
Severe Ozone SIP and its 2015 Moderate Ozone SIP. EPA will take
action on those SIP components in a separate rulemaking.
\23\ 2023 SIP Submittal, Document Set 1 of 7, ``05_Denver Post
Legal Ad'' and ``06_Meeting Agenda.''
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Finally, for purposes of administrative efficiency, EPA is
proposing to act on Colorado SIP revisions unrelated to the State's
Marginal ozone nonattainment obligations. On March 22, 2021, CDPHE
submitted a SIP revision (``2021 SIP Submittal'') that included
revisions to Regulation 3, Part A to update the date of incorporation
by reference of global warming potentials (GWPs) as defined in 40 CFR
part 98, subpart A, table A-1.\24\ Colorado met the CAA's reasonable
notice and public hearing requirements through notice in the Denver
Legal Post on September 26, 2020, and a public hearing on December 16-
18, 2020.\25\ Although EPA approved other elements of the 2021 SIP
Submittal in a March 27, 2023 final rule, we did not finalize action on
the revisions updating the date of incorporation by reference of GWPs
for the reasons discussed in that final rule \26\ and below. In
addition, Colorado's 2023 SIP Submittal included revisions to
Regulation 3 related to the incorporation by reference of GWPs that
build upon the aforementioned 2021 SIP Submittal revisions. We now
propose to act concurrently on the Regulation 3 GWP revisions from both
the 2021 SIP Submittal and subsequent 2023 SIP Submittal.
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\24\ 2021 SIP Submittal, Document Set 1 of 6, ``01_Submittal
Letter to EPA--121820_Ozone SIP, Reg 3, Reg 7, Air Quality
Stds_signed''; ``03_Hearing Notice & Proposed Language_R3.'' The
2021 SIP Submittal was deemed complete by operation of law six
months after submission.
\25\ 2021 SIP Submittal, Document Set 1 of 6, ``05_Denver Post
Legal Ad'' and ``06_Meeting Agenda.''
\26\ 88 FR 18054, 18054 (Mar. 27, 2023).
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II. The EPA's Evaluation of Colorado's SIP Submittals
A. Base Year Emissions Inventory
Under CAA sections 172(c)(3) and 182(a)(1), Colorado must submit a
comprehensive, accurate, and current accounting of actual emissions of
ozone precursors from all sources (point, nonpoint, nonroad mobile, and
on-road mobile sources) in the 2015 DMNFR Nonattainment Area. EPA's SIP
Requirements Rule specifies that the inventory year shall be selected
consistent with the baseline year for the Reasonable Further Progress
(RFP) plan under 40 CFR 51.1310(b),\27\ which EPA identified as
2017.\28\ The rule also requires states to report ``ozone season day
emissions'' in the base year inventory,\29\ as described in other EPA
regulations:
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\27\ 40 CFR 51.1315(a).
\28\ 83 FR 62998, 63005.
\29\ 40 CFR 51.1315(c).
Ozone season day emissions means an average day's emissions for
a typical ozone season work weekday. The state shall select, subject
to EPA approval, the particular month(s) in the ozone season and the
day(s) in the work week to be represented, considering the
conditions assumed in the development of RFP plans and/or emissions
budgets for transportation conformity.\30\
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\30\ 40 CFR 51.1300(q).
Based on EPA's 2017 Emissions Inventory Guidance for Implementation
of Ozone and Particulate Matter National Ambient Air Quality Standards
(NAAQS) and Regional Haze Regulations (2017 Emissions Inventory
Guidance), the selected ozone season day should be representative of
the conditions leading to nonattainment.\31\
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\31\ 2017 Emissions Inventory Guidance, 75.
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To satisfy these requirements, Colorado included a 2017 base year
inventory in its 2020 SIP Submittal.\32\ Following EPA's revised
designation of the 2015 DMNFR Nonattainment Area, Colorado then
submitted a revised base year inventory in its 2023 SIP Submittal as a
superseding supplement to its 2020 SIP Submittal to account for
emissions from the revised nonattainment area, including the whole of
Weld County.\33\
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Consistent with the SIP Requirements Rule, the revised inventory uses
2017 as the base year for SIP planning purposes.\34\ It was developed
for a typical July day in 2017 to estimate NOX and VOC
emissions during the peak summer ozone season, which is representative
of the conditions leading to nonattainment in the 2015 DMNFR
Nonattainment Area.\35\ Consistent with the 2017 Emissions Inventory
Guidance, the inventory estimates emissions from all major source
categories including point sources, nonpoint sources, on-road and
nonroad mobile sources, and biogenic sources.\36\ Additional
information describing Colorado's general methodology for compiling its
emissions inventory may be found in the State's inventory technical
support document included in the 2023 SIP Submittal.\37\
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\32\ 2020 SIP Submittal, ``08-Denver 2017 Ozone NAA Inventory.''
\33\ 2023 SIP Submittal, Document Set 6 of 7, ``2017 Baseline
Inventory Update TSD FINAL,'' 1-2 (``2017 Baseline Inventory Update
TSD''); 2023 SIP Submittal, Document Set 6 of 7, ``APCD_FINAL_SIP-
2015,'' ch. 3 (``Revised Milestone Emission Inventory'').
\34\ 83 FR 62998, 63005, 63011 n.29.
\35\ 2017 Baseline Inventory Update TSD, 2.
\36\ Id.; Revised Milestone Emission Inventory, ch. 3; 2017
Emissions Inventory Guidance, 19, 81.
\37\ 2017 Baseline Inventory Update TSD, 1-14.
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Tables 1 and 2 of this proposed rule show 2017 ozone season day
emissions for the 2015 DMNFR Nonattainment Area in units of tons per
day (tpd). Table 1 summarizes anthropogenic VOC and NOX
emissions by source sector. Table 2 summarizes biogenic VOC and
NOX emissions, including those from fire and other naturally
occuring emissions not included as anthropogenic emissions in Table 1.
The anthropogenic portion of the base year inventory for a
nonattainment area may serve as the Rate of Progress (ROP)/RFP baseline
inventory for Moderate and higher nonattainment classifications.\38\
The following sections II.A.1-II.A.6 describe the State's inventory of
emissions from the various source sectors in more detail.
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\38\ 2017 Emissions Inventory Guidance, 41.
Table 1--Denver Metro/North Front Range Nonattainment Area 2017 VOC and
NOX Base Year Anthropogenic Emissions Inventory
[Tons/Day] \39\
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Source type NOX VOC
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Point................................................. 24.2 21.9
Nonpoint.............................................. 0.1 80.1
On-road Mobile........................................ 57.4 48.1
Nonroad Mobile........................................ 42.9 44.5
Oil & Gas............................................. 78.2 211.1
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Total............................................. 202.9 405.7
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Table 2--Denver Metro/North Front Range Nonattainment Area 2017 VOC and
NOX Base Year Biogenic Emissions
[Tons/Day] \40\
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Source type NOX VOC
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Biogenic.............................................. 26.5 419.0
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1. Point Source Emissions
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\39\ Revised Milestone Emission Inventory, 3.2.2.1, tbl. 7.
\40\ Id. at 3.2.2.7, tbl. 15.
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Point sources are large, stationary, identifiable sources of
emissions that release pollutants into the atmosphere. In its 2017 base
year inventory, the State included point source emissions from source
categories including power plants/electric generating units, external
combustion boilers, industrial processes, internal combustion sources,
petroleum/solvent evaporation not associated with the oil and gas
industry, and waste disposal.\41\ The SIP Requirements Rule provides
that emissions from point sources shall be reported according to the
thresholds of EPA's Air Emissions Reporting Requirements (AERR).\42\
The 2017 Emissions Inventory Guidance directs those preparing point
source inventories to volume 2 of the Emissions Inventory Improvement
Program technical report series for information on point source
inventory methodology.\43\ This resource describes the three principal
methods for estimating point source emissions as source testing, mass
balance calculations, and emission factors, with a fourth method
utilizing engineering calculations if the principal methods are not
possible.\44\
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\41\ Colorado's methodology and results for the point source
category are described in section 3.2.2.3 of the Revised Milestone
Emission Inventory.
\42\ 40 CFR 51.1315(d).
\43\ 2017 Emissions Inventory Guidance, 81-82.
\44\ U.S. EPA, EIIP Technical Report Series Vol. II, Ch. 1:
``Introduction to Stationary Point Source Emission Inventory
Development'' (May 2001), 1.4-1--1.4-3.
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Colorado obtained its point source data from the APEN database, the
State's emissions reporting system for stationary sources.\45\ Colorado
requires an APEN to be filed for emission points in a nonattainment
area with uncontrolled actual emissions of one ton per year or more of
any criteria pollutant that the area is designated nonattainment
for.\46\ In order of preferred methodology, APEN emission estimates are
based on actual test data or, in the absence of such data, on mass
balance calculations, published emission factors, or engineering
calculations.\47\ Since Colorado's base year inventory is consistent
with the reporting thresholds in the AERR and uses methods for
estimating emissions recommended by EPA guidance, the base year
inventory adequately addresses emissions from the point source
category.
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\45\ Revised Milestone Emission Inventory, 3.2.2.3.
\46\ 5 CCR 1001-5:3A.II.B.3.a.
\47\ 5 CCR 1001-5:3A.II.B.1.
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2. Nonpoint Source Emissions
Nonpoint sources are sources of pollution that are small and
numerous and that have not been inventoried as specific point sources
or mobile sources. They include a wide range of categories such as
coatings, household and personal care products, pesticides, automotive
aftermarket products, and sealants. Inventorying nonpoint sources
involves grouping them by category and estimating their emissions
collectively using one methodology.
The State developed the nonpoint source emissions inventory \48\
from the 2016v2 EPA modeling platform,\49\ which includes emission
inventories for 2016 and 2023. To establish emissions for 2017 from the
2016v2 platform, the State used a linear interpolation from 2016 to
2023. Because a portion of Larimer County is not part of the 2015 DMNFR
Nonattainment Area, the State scaled the whole-county emissions by the
ratio of the county population residing within the nonattainment area
boundary based on 2020 census block data--0.9776--to determine an
accurate emissions contribution for the relevant part of Larimer
County. The nonpoint source portion of Colorado's emissions inventory
includes source categories addressed in the nonpoint portion of the
inventories developed for EPA's 2016v2 platform. Colorado used EPA
estimates for the nonpoint source category and apportioned partial
county emissions using methods consistent with the 2017 Emissions
Inventory Guidance.\50\
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Therefore, the base year inventory adequately addresses emissions from
the nonpoint source category.
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\48\ Colorado's methodology and results for the nonpoint source
category are described in section 3.2.2.4 of the Revised Milestone
Emission Inventory.
\49\ The 2016v2 modeling platform includes a set of emissions
inventories, data files, software tools, and scripts used for air
quality modeling. Files and technical support documents are
available at: https://www.epa.gov/air-emissions-modeling/2016v2-platform. The 2016v2 modeling platform draws on data from the 2017
National Emissions Inventory and includes point sources, nonpoint
sources, commercial marine vessels, on-road and nonroad mobile
sources, and fires for the U.S., Canada, and Mexico. U.S. EPA,
``Technical Support Document (TSD): Preparation of Emissions
Inventories for the 2016v2 North American Emissions Modeling
Platform,'' EPA-454/B-22-001 (Feb. 2022), 1-2.
\50\ 2017 Emissions Inventory Guidance, 72-73, 131-32.
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3. On-Road Mobile Source Emissions
For on-road mobile sources (vehicles operated on public roadways),
Colorado's 2017 base year inventory includes emissions from passenger
cars, motorcycles, light trucks, refuse/single-unit trucks, short/long-
haul trucks, and buses.\51\ The State estimated these emissions using
EPA's Motor Vehicle Emissions Simulator model version 3 (MOVES3 \52\)
along with link-level (roadway) vehicle miles traveled (VMT) provided
by the two metropolitan planning organizations that serve the 2015
DMNFR Nonattainment Area, the Denver Regional Council of Governments
and the North Front Range Metropolitan Planning Organization. The State
based VMT on travel demand model output data from those two
organizations and apportioned it to the nonattainment area at the
roadway level using Geographic Information Systems. Additional MOVES3
model inputs include vehicle population and age distribution, roadway
activity data (speed and time of day), roadway classifications (urban,
rural, restricted, unrestricted), fuel properties, inspection and
maintenance program characteristics, and hourly meteorology. These
model inputs are described in greater detail in EPA's MOVES3 technical
guidance.\53\ Specific MOVES3 on-road inputs used by the State are
identified in Appendix A to the 2017 Baseline Inventory Update
Technical Support Document. The State based model inputs on conditions
on an average July weekday and used the MOVES3 default fuel
formulation. It calculated NOX and VOC emission factors from
MOVES3 for each vehicle type and then multiplied these emission factors
by the roadway-level VMT to establish on-road mobile source emissions.
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\51\ Colorado's methodology and results for the on-road mobile
source category are described in section 3.2.2.6 of the Revised
Milestone Emission Inventory and in section 3.1.1 and Appendix A of
the 2017 Baseline Inventory Update TSD.
\52\ MOVES3 files and technical support documents are available
at: https://www.epa.gov/moves/moves-versions-limited-current-use.
\53\ U.S. EPA, ``MOVES3 Technical Guidance: Using MOVES to
Prepare Emission Inventories for State Implementation Plans and
Transportation Conformity,'' EPA-420-B-20-052 (Nov. 2020), 26-58.
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Colorado's on-road mobile source emissions inventory methodology
follows the SIP Requirements Rule, which states that ``the latest
approved version of the [MOVES] model should be used to estimate
emissions from on-road and certain nonroad transportation sources.''
\54\ MOVES3 was the latest approved version of the model available at
the time that the State developed its 2017 base year inventory.
Colorado used local data on vehicle/roadway activity, meteorological
conditions, fuel use, and other information characterizing the DMNFR
area in 2017, as called for by EPA's 2017 Emissions Inventory
Guidance.\55\ Therefore, the base year inventory adequately addresses
emissions from the on-road mobile source category.
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\54\ 83 FR 62998, 63022.
\55\ 2017 Emissions Inventory Guidance, 89-90.
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4. Nonroad Mobile Source Emissions
Nonroad mobile sources are mobile sources other than on-road
vehicles, including engines used in lawn and garden equipment,
commercial and industrial equipment, construction and mining equipment,
aircraft, and locomotives. Colorado's 2017 base year inventory used
EPA's MOVES-Nonroad model to estimate emissions from nonroad mobile
sources in the 2015 DMNFR Nonattainment Area, except for emissions from
aviation, locomotives, and rail yards.\56\ MOVES-Nonroad exists as a
separate module from the on-road modeling capabilities within MOVES3.
The specific MOVES3 nonroad inputs used by the State are identified in
Appendix A to the 2017 Baseline Inventory Technical Support Document.
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\56\ Colorado's methodology and results for the nonroad mobile
source category are described in section 3.2.2.5 of the Revised
Milestone Emission Inventory and in section 3.1.2 and Appendix A of
the 2017 Baseline Inventory Update TSD.
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The State estimated aviation emissions based on data provided by
Denver International Airport (DIA) on fleet composition and activity
level, including estimates of emissions from aircraft and ground
support equipment such as auxiliary power units. It estimated 2017
aviation emissions from other airports within the nonattainment area
using a linear interpolation between the 2016 and 2023 point source
emissions from the 2016v2 EPA modeling platform, with DIA emissions
excluded. The State also used the 2016v2 modeling platform to estimate
emissions from railroad locomotives and rail yard switcher locomotives.
It apportioned line-haul locomotive activity levels by track mileage in
the nonattainment area. As with the aviation and nonpoint source
sectors, Colorado determined 2017 locomotive emissions from a linear
trend between 2016 and 2023 estimates from the 2016v2 platform.
As directed in the SIP Requirements Rule,\57\ Colorado used the
most recently available version of EPA's MOVES-Nonroad model to
estimate emissions from certain nonroad sources. Furthermore, Colorado
used EPA's own 2016v2 platform to account for emissions from aviation,
locomotives, and rail yards not covered by the MOVES-Nonroad model.
Finally, for emissions specifically from DIA, the major international
airport in the DMNFR nonattainment area, the State relied on data
provided from the airport that provides valuable detail regarding DIA
emissions. Therefore, the base year inventory adequately addresses
emissions from the non-road mobile source category.
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\57\ 83 FR 62998, 63022.
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5. Oil and Gas Emissions
To inventory oil and gas emissions for its 2023 SIP Submittal,
Colorado relied on extensive industry outreach it had conducted between
2015-2018 to develop emission inventories for its 2008 8-hour Ozone
DMNFR Nonattainment Area Moderate and Serious SIPs.\58\ The State based
its approach to the oil and gas emissions component of its inventory on
actual and survey data from operators in the specific geological basin.
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\58\ Colorado's methodology and results for the oil and gas
source category are described in section 3.2.2.2 of the Revised
Milestone Emission Inventory and in sections 3.2 and 3.3 of the 2017
Baseline Inventory Update TSD.
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Colorado's 2017 base year emissions inventory categorizes emissions
from the oil and gas sector into point sources, condensate/oil tanks,
and nonpoint sources. The State used APEN reported data to determine
emissions from point sources, including external combustion boilers,
industrial processes, internal combustion sources, petroleum/solvent
evaporation, and waste disposal. As described previously, Colorado's
APEN reporting program meets the point source thresholds in EPA's AERR
and uses methods for estimating emissions consistent with that
recommended by EPA guidance. Therefore, the base year inventory
adequately addresses the point source component of oil and gas
emissions.
Colorado based condensate tank emissions (the largest single source
of VOC emissions in the 2017 base year inventory) on APEN reported
data, data collected by the Colorado Energy and Carbon Management
Commission, and data reported directly by the industry. The State
developed site-specific uncontrolled tank emission factors and
multiplied them by facilities' production in barrels per year. It then
[[Page 25221]]
adjusted the resulting emissions to account for several factors
relevant to condensate tanks: a control device's destruction and
removal efficiency (DRE) of emissions; the capture efficiency of a
control device (a fractional factor intended to discount a control
device's DRE to account for actual operating conditions and potential
process/device upsets); and the rule effectiveness of regulations (a
discount factor that scales a control device's DRE downward to account
for a degree of noncompliance with applicable regulations). Since
Colorado estimated condensate tank emissions using APEN reported data
as well as additional industry-specific data and site-specific emission
factors, the base year inventory adequately addresses emissions from
the condensate tank portion of the oil and gas component.
Oil and gas nonpoint sources in Colorado's inventory include
emissions from certain production equipment and operations (e.g.,
emissions from well pad engines, truck loading, pneumatic devices,
fugitives, blowdowns, process heaters, separator control, and water
tank losses). Nonpoint source emissions also result from pre-production
operations, including from drill rig engines, hydraulic fracturing
engines, drilling mud degassing, and venting during completion
operations. The State estimated some of these emissions based on
facility/equipment level data reported by 11 producers as part of the
stakeholder group it convened in 2018, with emissions scaled to account
for the entirety of the 2015 DMNFR Nonattainment Area including the
whole of Weld County. Colorado used 2017 NEI data to supplement pre-
production emissions for categories not included in producer-submitted
data. The State determined drilling mud degassing emissions that were
not captured in producer-submitted information, or the 2017 NEI, from
EPA's 2016v2 modeling platform by interpolating emissions to 2017 from
2016 and 2023 emissions. Since Colorado relied on basin-specific
producer submitted information in developing its oil and gas nonpoint
source inventory, in addition to emissions from EPA's own 2017 NEI and
2016v2 platform, the base year inventory adequately addresses emissions
from the oil and gas nonpoint source component.
6. Biogenic Emissions
Biogenic emissions come from natural sources. Colorado included a
2017 inventory of biogenic emissions separate from the anthropogenic
portion of the inventory.\59\ The State used EPA's Biogenic Emissions
Inventory System (BEIS), version 3, which EPA developed specifically
for estimating biogenic emissions for inventories.\60\ Since Colorado
used the BEIS model to estimate emissions, as recommended by EPA
guidance, the base year inventory adequately addresses emission from
the biogenic source category.
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\59\ Colorado's methodology and results for the biogenic source
category are described in section 3.2.2.7 of the Revised Milestone
Emission Inventory.
\60\ 2017 Emissions Inventory Guidance, 101-102.
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7. EPA's Evaluation of the Base Year Emissions Inventory
Based on EPA's review and evaluation of the methodologies,
procedures, and results in Colorado's 2017 base year emissions
inventory, we propose to find that the inventory meets the requirements
of CAA sections 172(c)(3) and 182(a)(1) and the SIP Requirements Rule.
The base year inventory is based on the most current and accurate
information that was available to the State at the time the inventory
was developed. Additionally, the 2017 inventory comprehensively
addresses all source categories in the 2015 DMNFR Nonattainment Area
including the whole of Weld County and was developed consistent with
the relevant EPA emissions inventory regulations, guidance, and models.
B. Certification of Existing Emission Statement Rule and Addition of
Annual Certification Requirement
Under CAA section 182(a)(3)(B), Colorado must implement an emission
statement rule requiring certain stationary sources that emit VOC or
NOX in the nonattainment area to report on their emissions
at least annually.\61\ Section 182(a)(3)(B)(ii) specifies that a state
may waive this requirement for sources that emit less than 25 tpy of
VOC or NOX if the state includes emissions from such sources
in its base year or periodic inventories.\62\ If a state already has an
EPA-approved emissions reporting regulation in place and determines
that it is adequate to meet the requirements of section 182(a)(3)(B),
EPA may accept a SIP revision with the state's written certification of
that determination in lieu of the state submitting new revised
regulations.\63\ In its 2020 SIP Submittal, Colorado certified that its
existing SIP-approved APEN program meets the source reporting
requirements for an emission statement rule under CAA section
182(a)(3)(B).\64\
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\61\ 42 U.S.C. 7511a(a)(3)(B)(i).
\62\ 42 U.S.C. 7511a(a)(3)(B)(ii).
\63\ 83 FR 62998, 63001-02.
\64\ Collectively, the information contained in ``01-Submittal
Letter to EPA,'' ``06-Issue Statement,'' and ``07-CAA Elements
Table'' in the 2020 SIP Submittal satisfies the certification
requirements outlined in the SIP Requirements Rule, 83 FR 62998,
63001-02.
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Colorado's APEN program requires stationary sources with
uncontrolled actual emissions of one tpy or more of any individual
criteria pollutant for which the area is in nonattainment to file an
APEN with the Colorado Air Pollution Control Division (APCD).\65\
Emission estimates reported on the APEN must be based on actual test
data or, in the absence of such data, on an alternative estimation
acceptable to the APCD.\66\ Each APEN must include the location of the
source; the operator's name and address; the nature of the facility,
process or activity; an estimate of the quantity and composition of
emissions; and other specified information that varies based on the
type of source.\67\ An APEN is valid for five years \68\ but must be
revised (1) annually whenever a significant change in annual actual
emissions occurs or (2) upon the occurrence of a triggering event, such
as a change in the owner/operator, the installation of new control
equipment, or the modification of a permit limitation.\69\ To ensure
the accuracy of APEN reported emissions between triggering events,
Colorado's 2023 SIP Submittal includes revisions to add section II.A.3
to Regulation 3, Part A.\70\ The new section II.A.3 requires stationary
sources in the ozone nonattainment area with the potential to emit 25
tpy or more of NOX or VOC to annually certify through an
APCD-approved format that annual actual emissions are as reported on
the source's APEN.
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\65\ 5 CCR 1001-5:3A.II.A.1, II.B.3.a.
\66\ 5 CCR 1001-5:3A.II.B.1.
\67\ 5 CCR 1001-5:3A.II.A.1.
\68\ 5 CCR 1001-5:3A.II.B.2.
\69\ 5 CCR 1001-5:3A.II.C.
\70\ 2023 SIP Submittal, Document Set 5 of 7, ``17_Reg Lang &
SBAP Adopted_R3.''
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EPA is proposing to concurrently approve Colorado's certification
of its APEN program in its 2020 SIP Submittal, as well as the State's
associated addition of the annual certification provision in section
II.A.3 to Regulation 3, Part A in its 2023 SIP Submittal, as meeting
the requirements for an emission statement rule under CAA section
182(a)(3)(B). As recommended by EPA guidance, the APEN program requires
certification of data accuracy and submission of source identification
information, operating schedule, emissions information, control
equipment information, and
[[Page 25222]]
process data.\71\ Since Colorado's 2017 base year inventory, as
described previously in this proposed rule, includes emissions from
sources below 25 tpy and is based on acceptable methodologies,
Colorado's APEN reporting program satisfies the criteria for the waiver
in CAA section 182(a)(3)(B)(ii). Therefore, EPA proposes to approve the
State's APEN reporting program under CAA section 182(a)(3)(B).
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\71\ U.S. EPA, ``Draft Guidance on the Implementation of an
Emission Statement Program'' (July 1992), 3.
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C. Other Revisions to Regulation 3, Part A
EPA is also proposing action on certain other revisions to
Regulation 3 unrelated to the State's Marginal ozone nonattainment
obligations. Colorado's 2021 and 2023 SIP Submittals included several
revisions to Regulation 3, Parts A, B, and D. In this rulemaking, we
are proposing action on the State's revisions to Regulation 3, Part A
related to the date of incorporation by reference of global warming
potentials (GWPs) and the computation of the mass of carbon dioxide
equivalent.\72\ The revisions in the 2021 and 2023 SIP Submittals that
are described below have State effective dates of February 14, 2021,
and February 14, 2023, respectively. The revisions do not interfere
with attainment or maintenance of any of the NAAQS and would not
interfere with any other applicable requirement of the CAA, and are
therefore approvable under CAA section 110(l). EPA will propose action
on the remaining revisions to Regulation 3, Parts A, B, and D in a
separate rulemaking.
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\72\ References to specific sections of Regulation 3 in sections
II.C.1 and II.C.2 of this proposed rule are to the versions of
Regulation 3 the State included in the 2021 and 2023 SIP Submittals,
namely: 2021 SIP Submittal, Document Set 4 of 6, ``16_Reg Lang &
SBAP Adopted_R3''; 2021 SIP Submittal, Document Set 6 of 6, ``22_5
CCR 1001-5''; 2023 SIP Submittal, Document Set 5 of 7, ``17_Reg Lang
& SBAP Adopted_R3''; and 2023 SIP Submittal, Document Set 7 of 7,
``23_5 CCR 1001-5.''
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1. Regulation 3, Part A, Sections I.B.10 and 1.B.44.b.(i)--Date of
Incorporation by Reference of Global Warming Potentials
Colorado's Regulation 3, Part A, Section I.B.10 defines ``carbon
dioxide equivalent'' as a metric used to compare emissions of various
greenhouse gases. The metric is based in part on each gas's GWP as
codified in 40 CFR part 98, subpart A, table A-1, which Regulation 3
incorporates by reference. Regulation 3, Part A, Section I.B.44.b.(i),
which provides conditions under which GHGs are ``subject to
regulation,'' makes the same incorporation by reference. In its 2021
SIP Submittal, the State replaced the outdated November 20, 2013
incorporation by reference date with December 11, 2014 in both Sections
1.B.10 and 1.B.44.b.(i).\73\ However, while the November 20, 2013 date
was removed from Section 1.B.10 in the Code of Colorado Regulations,
the revised date was inadvertently omitted, leaving the incorporation
by reference without a corresponding date.\74\ Colorado's 2023 SIP
Submittal corrects that omission.\75\ Since December 11, 2014, is the
most recent date of revision to the GWPs in 40 CFR part 98, Subpart A,
Table A-1, EPA is proposing to approve the revisions from the 2021 and
2023 SIP Submittals that update the date of incorporation by reference
in Regulation 3, Part A, sections I.B.10 and 1.B.44.b.(i).
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\73\ 2021 SIP Submittal, Document Set 4 of 6, ``16_Reg Lang &
SBAP Adopted_R3.''
\74\ 2021 SIP Submittal, Document Set 6 of 6, ``22_5 CCR 1001-
5,'' 4.
\75\ 2023 SIP Submittal, Document Set 5 of 7, ``17_Reg Lang &
SBAP Adopted_R3.''
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2. Regulation 3, Part A, Section I.B.44.(b).(i)--Computation of Mass of
Carbon Dioxide Equivalent
EPA is proposing to approve an additional revision in Colorado's
2023 SIP Submittal to Regulation 3, Part A, Section I.B.44.b.(i).\76\
The revision removes language stating that, prior to July 21, 2014, the
mass of carbon dioxide shall not include emissions resulting from the
combustion or decomposition of non-fossilized and biodegradable organic
material. The removed language is consistent with the definition of
``subject to regulation'' at 40 CFR 70.2, which instructed how to
compute the mass of carbon dioxide equivalent before July 21, 2014.
This language was meant to defer the application of Prevention of
Significant Deterioration and Title V programs to certain sources of
biogenic carbon dioxide for three years.\77\ Because the deferral
period has since expired, continued inclusion of this language in the
SIP is unnecessary.
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\76\ Id.
\77\ 76 FR 43490, 43490 (July 20, 2011).
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III. Proposed Action
We are proposing to approve elements of Colorado's July 27, 2020,
March 22, 2021, and June 26, 2023 SIP Submittals. Specifically, we are
proposing to approve Colorado's 2017 base year inventory under CAA
sections 172(c)(3) and 182(a)(1). We are proposing to approve
Colorado's certification of its APEN reporting program (July 27, 2020
SIP Submittal) and the addition of the annual certification requirement
in Section II.A.3 to Regulation 3, Part A (June 26, 2023 SIP Submittal)
as meeting the emission statement rule requirements of CAA section
182(a)(3)(B). We are also proposing to approve certain revisions to
Regulation 3, Part A, specifically to the date of incorporation by
reference of GWPs in Sections 1.B.10 and 1.B.44.b.(i) (March 22, 2021
and June 26, 2023 SIP Submittals) and to the computation of the mass of
carbon dioxide equivalent in Section 1.B.44.b.(i) (June 26, 2023 SIP
Submittal).
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 the APCD revisions regarding annual APEN
certification, updated incorporation by reference dates of CFR global
warming potentials, and revisions related to the computation of carbon
dioxide equivalent, as described in sections II.B and II.C of this
proposed rule. The EPA has made, and will continue to make, these
materials generally available through www.regulations.gov and at the
EPA Region 8 Office. Please contact the person identified in the FOR
FURTHER INFORMATION CONTACT section of this preamble for more
information.
V. Statutory and Executive Order Reviews
Under the CAA, the Administrator is required to approve a SIP
submission that complies with the provisions of the Act and applicable
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in
reviewing SIP submissions, the EPA's role is to approve state choices,
provided that they meet the criteria of the CAA. Accordingly, this
action merely proposes to approve state law as meeting Federal
requirements and does not impose additional requirements beyond those
imposed by state law. For that reason, this action:
Is not a ``significant regulatory action'' subject to
review by the Office of Management and Budget under Executive Orders
12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21,
2011);
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
[[Page 25223]]
under the Regulatory Flexibility Act (5 U.S.C. 601 et seq.);
Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4);
Does not have Federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
Is not an economically significant regulatory action based
on health or safety risks subject to Executive Order 13045 (62 FR
19885, April 23, 1997);
Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001);
Is not subject to requirements of section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the CAA; and
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).
Executive Order 12898 (Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations, 59 FR 7629,
Feb. 16, 1994) directs Federal agencies to identify and address
``disproportionately high and adverse human health or environmental
effects'' of their actions on minority populations and low-income
populations to the greatest extent practicable and permitted by law.
EPA defines environmental justice (EJ) as ``the fair treatment and
meaningful involvement of all people regardless of race, color,
national origin, or income with respect to the development,
implementation, and enforcement of environmental laws, regulations, and
policies.'' EPA further defines the term fair treatment to mean that
``no group of people should bear a disproportionate burden of
environmental harms and risks, including those resulting from the
negative environmental consequences of industrial, governmental, and
commercial operations or programs and policies.''
Colorado did not evaluate environmental justice considerations as
part of its SIP submittal; the CAA and applicable implementing
regulations neither prohibit nor require such an evaluation. EPA did
not perform an EJ analysis and did not consider EJ in this action.
Consideration of EJ is not required as part of this action, and there
is no information in the record inconsistent with the stated goal of
Executive Order 12898 of achieving environmental justice for people of
color, low-income populations, and Indigenous peoples.
List of Subjects in 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.
Authority: 42 U.S.C. 7401 et seq.
Dated: April 2, 2024.
KC Becker,
Regional Administrator, Region 8.
[FR Doc. 2024-07584 Filed 4-9-24; 8:45 am]
BILLING CODE 6560-50-P