Partial Approval and Partial Disapproval of Air Quality Implementation Plans; Arizona; West Pinal County; 1987 PM10, 1347-1362 [2020-29092]
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Federal Register / Vol. 86, No. 5 / Friday, January 8, 2021 / Proposed Rules
covering such items as the range of
potential purchasers of the Enterprise’s
core business lines and other significant
assets, as well as measures that, if taken
by the Enterprise, could minimize the
risk that its resolution would have
serious adverse effects on the national
housing finance markets and minimize
the amount of potential loss to the
Enterprise’s investors and creditors.
(b) Confidential treatment of
resolution plan. (1) The confidentiality
of each resolution plan and related
materials shall be determined in
accordance with applicable exemptions
under the Freedom of Information Act
(5 U.S.C. 552(b)), 12 CFR part 1202
(FHFA’s regulation implementing the
Freedom of Information Act), and 12
CFR part 1214 (FHFA’s regulation on
the availability of non-public
information).
(2) An Enterprise submitting a
resolution plan or related materials
pursuant to this part that desires
confidential treatment of the
information under 5 U.S.C. 552(b)(4), 12
CFR part 1202 (Freedom of Information
Act), and 12 CFR part 1214 (availability
of non-public information) may file a
request for confidential treatment in
accordance with those rules.
(3) To the extent permitted by law,
information comprising the confidential
section of a resolution plan will be
treated as confidential.
(4) To the extent permitted by law, the
submission of any nonpublic data or
information under this part shall not
constitute a waiver of, or otherwise
affect, any privilege arising under
Federal or state law (including the rules
of any Federal or state court) to which
the data or information is otherwise
subject. The submission of any
nonpublic data or information under
this part shall be subject to the
examination privilege.
tkelley on DSKBCP9HB2PROD with PROPOSALS
§ 1242.7 Review of resolution plans;
resubmission of deficient resolution plans.
(a) FHFA acceptance of resolution
plan; review for completeness. (1) After
receipt of a resolution plan, FHFA will
either acknowledge acceptance of the
plan for review or return the resolution
plan if FHFA determines that it is
incomplete or that substantial
additional information is required to
facilitate review of the resolution plan.
(2) If FHFA determines that a
resolution plan is incomplete or that
substantial additional information is
necessary to facilitate review of the
resolution plan:
(i) FHFA shall provide notice to the
Enterprise in writing of the area(s) in
which the resolution plan is incomplete
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or with respect to which additional
information is required; and
(ii) Within 30 days after receiving
such notice (or such other time period
as FHFA may establish in the notice),
the Enterprise shall resubmit a complete
resolution plan or such additional
information as requested to facilitate
review of the resolution plan.
(b) FHFA review of complete plan;
determination regarding deficient
resolution plan. (1) Following review of
a complete resolution plan, FHFA will
send a notification to each Enterprise
that:
(i) Identifies any deficiencies in the
Enterprise’s resolution plan (or confirms
that no deficiencies were identified);
(ii) Identifies any planned actions or
changes set forth by the Enterprise that
FHFA agrees could facilitate a rapid and
orderly resolution of the Enterprise; and
(iii) Provides any other feedback on
the resolution plan (including feedback
on timing of actions or changes to be
undertaken by the Enterprise). FHFA
will send the notification no later than
12 months after accepting a complete
plan, unless FHFA determines in its
discretion that extenuating
circumstances exist that require delay.
(2) A deficiency is an aspect of an
Enterprise’s resolution plan that FHFA
determines presents a weakness that,
individually or in conjunction with
other aspects, could undermine the
feasibility of the Enterprise’s resolution
plan.
(c) Resubmission of a resolution plan.
Within 90 days of receiving a notice of
deficiency, or such shorter or longer
period as FHFA may establish by
written notice to the Enterprise, an
Enterprise shall submit a revised
resolution plan to FHFA that addresses
all deficiencies identified by FHFA, and
that discusses in detail:
(1) Revisions to the plan made by the
Enterprise to address the identified
deficiencies;
(2) Any changes to the Enterprise’s
business operations and corporate
structure that the Enterprise proposes to
undertake to address a deficiency
(including a timeline for completing
such changes); and
(3) Why the Enterprise believes that
the revised resolution plan is feasible
and would facilitate a rapid and orderly
resolution by FHFA as receiver.
§ 1242.8 No limiting effect or private right
of action.
(a) No limiting effect on resolution
proceedings. A resolution plan
submitted pursuant to this part shall not
have any binding effect on FHFA when
appointed as conservator or receiver
under 12 U.S.C. 4617.
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(b) No private right of action. Nothing
in this part creates or is intended to
create a private right of action based on
a resolution plan prepared or submitted
under this part or based on any action
taken by FHFA with respect to any
resolution plan submitted under this
part.
Mark A. Calabria,
Director, Federal Housing Finance Agency.
[FR Doc. 2020–28812 Filed 1–7–21; 8:45 am]
BILLING CODE 8070–01–P
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Part 52
[EPA–R09–OAR–2020–0618; FRL–10018–
46–Region 9]
Partial Approval and Partial
Disapproval of Air Quality
Implementation Plans; Arizona; West
Pinal County; 1987 PM10
Nonattainment Area Requirements
Environmental Protection
Agency (EPA).
ACTION: Proposed rule.
AGENCY:
The Environmental Protection
Agency (EPA) is proposing to approve
in part and to disapprove in part the
state implementation plan (SIP) revision
submitted by the State of Arizona to
meet Clean Air Act (CAA or ‘‘Act’’)
requirements for the 1987 PM10 national
ambient air quality standards (NAAQS
or ‘‘standard’’) in the West Pinal County
PM10 nonattainment area. The State of
Arizona’s ‘‘2015 West Pinal Moderate
PM10 Nonattainment Area SIP’’ (‘‘West
Pinal County PM10 Plan’’) addresses the
CAA nonattainment area requirements
for the 1987 PM10 NAAQS, including
requirements for an emissions
inventory, an attainment demonstration,
reasonable further progress, reasonably
available control measures, contingency
measures, and motor vehicle emissions
budgets. The EPA is proposing to
approve the base year 2008 emissions
inventory for direct PM10 and to
disapprove the remaining elements of
the West Pinal County PM10 Plan.
DATES: Written comments must arrive
on or before February 8, 2021.
ADDRESSES: Submit your comments,
identified by Docket ID No. EPA–R09–
OAR–2020–0618 at https://
www.regulations.gov. For comments
submitted at Regulations.gov, follow the
online instructions for submitting
comments. Once submitted, comments
cannot be edited or removed from
Regulations.gov. The EPA may publish
any comment received to its public
SUMMARY:
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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, or if
you need assistance in a language other
than English or if you are a person with
disabilities who needs a reasonable
accommodation at no cost to you, please
contact the person identified in the FOR
FURTHER INFORMATION CONTACT section.
For the full EPA public comment policy,
information about CBI or multimedia
submissions, and general guidance on
making effective comments, please visit
https://www.epa.gov/dockets/
commenting-epa-dockets. If you need
assistance in a language other than
English or if you are a person with
disabilities who needs a reasonable
accommodation at no cost to you, please
contact the person identified in the FOR
FURTHER INFORMATION CONTACT section.
FOR FURTHER INFORMATION CONTACT: Jerry
Wamsley, Air Planning Office (ARD–2),
EPA Region IX, 75 Hawthorne Street,
San Francisco, CA 94105, (415) 947–
4111, or by email at wamsley.jerry@
epa.gov.
SUPPLEMENTARY INFORMATION:
Throughout this document, ‘‘we,’’ ‘‘us,’’
and ‘‘our’’ refer to the EPA.
tkelley on DSKBCP9HB2PROD with PROPOSALS
Table of Contents
I. Regulatory Context
A. PM10 Standard, Area Designations, and
SIPs
B. CAA and Regulatory Requirements for
Moderate PM10 Nonattainment Area SIPs
II. Submissions From the State of Arizona To
Address 1987 PM10 Standard
Requirements in the West Pinal County
Nonattainment Area
A. Summary of State Submissions
B. CAA Procedural Requirements for
Adoption and Submission of SIP
Revisions
III. Evaluation of the West Pinal County PM10
Plan
A. Emissions Inventories
B. PM10 Precursors
C. Reasonably Available Control Measures
Demonstration
D. Attainment Demonstration
E. Reasonable Further Progress
Demonstration
F. Contingency Measures
G. Motor Vehicle Emissions Budgets for
Transportation Conformity
IV. Proposed Action
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V. Statutory and Executive Order Reviews
I. Regulatory Context
A. PM10 Standard, Area Designations,
and SIPs
The EPA sets the National Ambient
Air Quality Standard (NAAQS) for
certain ambient air pollutants at levels
required to protect human health and
the environment. Particulate matter
with an aerodynamic diameter less than
or equal to a nominal ten micrometers,
or PM10, is one of these ambient air
pollutants for which the EPA has
established health-based standards. On
July 1, 1987, the EPA promulgated two
primary standards for PM10: A 24-hour
standard of 150 micrograms per cubic
meter (mg/m3); and an annual PM10
standard of 50 mg/m3. The EPA also
promulgated secondary PM10 standards
that were identical to the primary
standards.1 Because they are identical,
we refer to the primary and secondary
standards using the singular term,
NAAQS. Effective December 18, 2006,
EPA revoked the annual PM10 NAAQS
but retained the 24-hour PM10 NAAQS.2
An area attains the 24-hour PM10
NAAQS when the expected number of
days per calendar year with a 24-hour
concentration in excess of 150
micrograms per cubic meter (mg/m3)
(referred to herein as an ‘‘exceedance’’),
is equal to or less than one as
determined in accordance with 40 CFR
part 50, appendix K.3 Conversely, a
violation of the PM10 NAAQS occurs
when the number of expected annual
exceedances of the 24-hour NAAQS is
greater than one.
Most of Pinal County, Arizona,
including what is now the West Pinal
County PM10 nonattainment area, was
included in the ‘‘rest of state’’ area,
which was designated ‘‘unclassifiable’’
for the 24-hour PM10 NAAQS by
operation of law upon enactment of the
CAA, consistent with section
107(d)(4)(B)(iii). Until recently, this area
in Arizona remained designated
‘‘unclassifiable’’ for the 1987 24-hour
PM10 NAAQS. The CAA, under section
107(d)(3), authorizes the EPA to revise
the designation of, or ‘‘redesignate,’’
areas (or portions thereof) based on air
quality data, planning and control
considerations, or any other air-qualityrelated considerations that the EPA
deems appropriate.
On October 14, 2009, under CAA
section 107(d)(3)(A), the EPA notified
the Governor of Arizona and four tribal
leaders (whose areas of Indian country
1 52
FR 24634 (July 1, 1987).
FR 61144 (October 17, 2006).
3 See 40 CFR 50.6 and 40 CFR part 50, appendix
K.
2 71
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are located entirely, or in part, within
Pinal County) that the designation for
Pinal County, and any nearby areas that
may be contributing to the monitored
violations in Pinal County, should be
revised.4 Our decision to initiate the
redesignation process was due to
ambient data for 2006–2008 from PM10
monitoring sites within the County
showing widespread, frequent, and in
some instances, severe, violations of the
PM10 standard.
Effective July 2, 2012, the EPA
designated a portion of state lands in
Pinal County, Arizona (‘‘West Pinal
County’’) as nonattainment for the 1987
PM10 NAAQS based on monitoring data
from 2006–2008.5 West Pinal County is
located in central Arizona, southeast of
the Phoenix metropolitan area and
northwest of the city of Tucson. Pinal
County covers 5,365 square miles and
has two distinct western and eastern
regions with different characteristics
relevant to pollution formation. The
West Pinal County PM10 nonattainment
area is located within the western
region, characterized by low desert
valleys and an arid climate. The eastern
region is mountainous, with elevations
up to 6,441 feet.
As a result of the nonattainment
designation, EPA classified West Pinal
County as a ‘‘Moderate’’ PM10
nonattainment area. Consequently, by
January 2, 2014, Arizona was required
to submit a nonattainment plan SIP
revision for the 24-hour PM10 NAAQS
meeting relevant CAA requirements.
The State submitted a SIP revision
intended to meet these requirements on
December 21, 2015, and this ‘‘2015 West
Pinal Moderate PM10 Nonattainment
Area SIP’’ is the subject of this proposed
action. For a PM10 nonattainment area
classified as Moderate, section 188(c) of
the CAA provides that the Moderate
area attainment date is ‘‘as
expeditiously as practicable, but no later
than the end of the sixth calendar year
after the area’s designation as
nonattainment.’’ Consequently, the
applicable attainment date for the West
Pinal County area, designated
nonattainment in 2012, was as
expeditiously as practicable, but no later
than December 31, 2018.
CAA section 188(b)(2) requires the
EPA to determine whether a state has
4 Letter from Laura Yoshii, Acting Regional
Administrator to Governor Jan Brewer dated
October 14, 2009. The EPA notified the tribal
leaders of the Ak-Chin Indian Community, Gila
River Indian Community, San Carlos Apache Tribe
by letters dated December 30, 2009, and Tohono
O’odham Nation by letter dated September 21,
2010.
5 77 FR 32024 (May 31, 2012). The precise
boundaries for the West Pinal County
nonattainment area are described in 40 CFR 81.303.
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attained the 24-hour PM10 NAAQS in a
Moderate PM10 nonattainment area by
the applicable attainment date and
requires the EPA to make such a
determination within six months after
that date. If the EPA determines that a
Moderate area has not attained the
NAAQS by the relevant attainment date,
then the area is reclassified as a Serious
area by operation of law. On June 24,
2020, the EPA determined that the West
Pinal County nonattainment area had
not attained the 1987 24-hour PM10
NAAQS by December 31, 2018, the
outermost permissible statutory
attainment date for the area.6 This
determination was based on our
calculation of the PM10 design value for
the West Pinal County nonattainment
area over the 2016–2018 period, using
complete, quality-assured, and certified
PM10 monitoring data.
The basis for the EPA’s June 24, 2020
finding of failure to attain the PM10
NAAQS and the margin by which the
area failed to attain indicate that the
Moderate plan’s modeled attainment
demonstration, which incorrectly
predicted attainment of the PM10
NAAQS by December 31, 2018, is not
approvable. Because the modeled
attainment demonstration is not
approvable, as described in section III.D,
other elements of the West Pinal County
PM10 Plan that are dependent upon the
modeled attainment demonstration are
likewise not approvable, e.g., the
emission controls imposed by the State
to meet reasonably available control
measure/reasonably available control
technology (RACM/RACT) requirements
based on the predicted sufficiency of
those controls to result in attainment by
the intended attainment date. If
finalized as we propose, our disapproval
of most elements of the Moderate plan
will start sanctions and Federal
implementation plan (FIP) clocks,
which can be turned off by the EPA’s
approval of new plan elements for the
PM10 NAAQS that correct the
deficiencies within the Moderate plan.
With the EPA’s reclassification of the
West Pinal County area to Serious,
Arizona now has an obligation to
submit, by January 24, 2022, a
nonattainment plan SIP revision that
complies with the statutory and
regulatory requirements for Serious
PM10 nonattainment plans and that
demonstrates attainment of the PM10
NAAQS as expeditiously as practicable,
but no later than December 31, 2022.
Although reclassification of an area
from Moderate to Serious does not
eliminate a state’s obligation to meet
Moderate area nonattainment plan
6 85
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B. CAA and Regulatory Requirements
for Moderate PM10 Nonattainment Area
SIPs
Along with the new designations,
classifications, and attainment dates, the
Clean Air Act Amendments of 1990
established new nonattainment area
planning requirements. The air quality
planning requirements for Moderate
PM10 nonattainment areas are set out in
subparts 1 and 4 of the CAA, including
sections 110, 172, and 189 of the statute.
We discuss these sections of the Act in
more detail later during our review of
each plan element. Also, the EPA has
issued guidance, in a document we refer
to as the General Preamble, describing
how we will review state nonattainment
plan SIP submissions under Title I of
the CAA, including such SIP
submissions for Moderate PM10
nonattainment areas.7 In general, states
must include the following elements in
nonattainment plans for Moderate areas
for purposes of the 1987 24-hour PM10
NAAQS: A comprehensive, accurate,
and current emissions inventory of
emissions sources in the nonattainment
area; provisions to implement RACM/
RACT for the appropriate sources and
pollutants in the nonattainment area;
provisions demonstrating reasonable
further progress (RFP), including
quantitative milestones towards
attainment of the PM10 NAAQS as
expeditiously as practicable, along with
quantitative milestones for evaluation of
RFP at set times; contingency measures
that will provide for additional
emissions reductions automatically in
the event that the state fails to meet RFP
or to attain the NAAQS by the
applicable attainment date in the area;
and, a motor vehicle emissions budget
for the purpose of determining the
conformity of transportation programs
and plans developed by state
transportation agencies.
7 57 FR 13498 (April 16, 1992) and 57 FR 18070
(April 28, 1992).
FR 37756 (June 24, 2020).
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requirements, the EPA anticipates that
Arizona’s submission of an approvable
Serious area nonattainment plan would
also satisfy the State’s Moderate area
nonattainment plan obligations. For
example, an approvable Serious area
nonattainment plan would satisfy the
Act’s requirements for imposing best
available control measures, including
best available control technology
(BACM/BACT), which would
presumably satisfy the less stringent
requirements for RACM/RACT.
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II. Submissions From the State of
Arizona To Address the 1987 PM10
Standard Requirements in the West
Pinal County Nonattainment Area
A. Summary of State Submissions
As a result of the May 31, 2012
nonattainment designation, West Pinal
County was classified as a Moderate
PM10 nonattainment area. Within 18
months from the July 2, 2012 effective
date of the designation, or January 2,
2014, the State was required to submit
a nonattainment plan meeting Moderate
area plan requirements, including
emission control measures for West
Pinal County designed to attain the 1987
24-hour PM10 NAAQS as expeditiously
as practicable, but no later than
December 31, 2018.
On December 21, 2015, Arizona
submitted the West Pinal County PM10
Plan, intended to address the Moderate
area nonattainment requirements, to the
EPA as a revision to the Arizona SIP.8
The West Pinal County PM10 Plan is
organized into seven chapters and nine
appendices. The nine appendices
provide support for the plan and are
divided into the following categories:
Technical support and documentation
(appendices A–D, F), SIP adoption
authority and public notice and hearing
documentation (appendix E) and control
measure submittals (appendices G–I).
Appendices G, H, and I contain
control measures submitted with the
West Pinal County PM10 Plan in the
form of rules, statutes, and other
supporting documents. We are not
proposing to act on the submitted
control measures in this proposed
action on the West Pinal County PM10
Plan. Previously, the EPA approved into
the Arizona SIP the submitted control
measures that regulate fugitive dust,
construction dust, and crop operations.9
In a separate Federal Register notice, we
intend to take action on the remainder
of the State’s submitted rules, namely,
an update to its agricultural best
management practices (AgBMP) statute,
and the AgBMP rules for animal
operations in Pinal County.
B. CAA Procedural Requirements for
Adoption and Submission of SIP
Revisions
CAA sections 110(a) and 110(l)
require a state to provide reasonable
public notice and opportunity for public
hearing prior to the adoption and
submission of a SIP revision to the EPA
8 Letter dated December 21, 2015, from Eric C.
Massey, Director, Air Quality Division, Arizona
Department of Environmental Quality, to Jared
Blumenfeld, Regional Administrator, EPA Region
IX.
9 82 FR 20267 (May 1, 2017).
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for evaluation under section 110(k) and
other applicable substantive
requirements. To meet this procedural
requirement, a state must include
evidence that it provided adequate
public notice and an opportunity for a
public hearing, consistent with the
EPA’s implementing regulations in 40
CFR 51.102.
The Arizona Department of
Environmental Quality (ADEQ)
provided public notice and opportunity
for public comment on the West Pinal
County PM10 Plan. On October 19, 2015,
ADEQ released the West Pinal County
PM10 Plan for public review and
published a notice of public meeting to
be held on November 19, 2015, to
consider adoption of the West Pinal
County PM10 Plan.10 On November 19,
2015, ADEQ held the public hearing and
subsequently adopted the West Pinal
County PM10 Plan as a revision to the
Arizona SIP.11 Under authority
provided by Arizona state law, on
December 21, 2015, Eric Massey,
Director of the Air Quality Division,
ADEQ, submitted the West Pinal County
PM10 Plan to the EPA.12 On June 21,
2016, the West Pinal County PM10 Plan
became complete by operation of law.13
Based on information provided in the
SIP submissions summarized above, the
EPA has determined that the public
hearing was properly noticed.
Therefore, we find that the submittal of
the West Pinal County PM10 Plan meets
the procedural requirements for public
notice and hearing in CAA sections
110(a) and 110(l) and 40 CFR 51.102.
III. Evaluation of the West Pinal County
PM10 Plan
A. Emissions Inventories
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1. Statutory and Regulatory
Requirements
CAA section 172(c)(3) requires a state
to submit for each PM10 nonattainment
area a ‘‘base year inventory’’ that is a
comprehensive, accurate, current
10 ‘‘Arizona Department of Environmental Quality
and Public Comment Period and Hearing on the
Proposed Arizona State Implementation Plan
Revision, Attainment Plan for the West Pinal
County PM10 Planning Area (1987 NAAQS)’’
published in the Arizona Republic October 19 and
20, 2015; Exhibit E–III, Appendix E, West Pinal
County PM10 Plan.
11 ‘‘Public Hearing Presiding Officer
Certification’’ signed by Naveen Savarirvayan,
Presiding Officer, November 19, 2015 and
notarized; Exhibit E–VI, Appendix E, West Pinal
County PM10 Plan. The hearing transcript and the
public comments and State responses are found at
Exhibit E–VIII and Exhibit E–VII, respectively,
within Appendix E, West Pinal County PM10 Plan.
12 Letter dated December 21, 2015 from Eric C.
Massey, Director, Air Quality Division, ADEQ to
Jared Blumenfeld, Regional Administrator, EPA
Region IX.
13 42 U.S.C. 7410(k)(1)(B).
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inventory of actual emissions from all
sources of the relevant pollutant or
pollutants in the area. Also, the state
should submit a second projected
‘‘attainment year inventory’’ for the year
in which the state projects that the area
will attain the PM10 standards. The state
should include documentation
explaining how it calculated the
emissions data. When estimating mobile
source emissions, states should use the
latest emissions models and planning
assumptions available at the time the
SIP is developed.14
The state must meet several general
requirements for base year emissions
inventories, consistent with CAA
section 172(c)(3). First, the emissions
inventory year must be one of the 3
years used for the EPA PM10
nonattainment designation for the area,
or an alternative year agreed upon by
the EPA and the state as more reflective
of the causes and sources of violations
of the PM10 standard that meet the
criteria in CAA section 172(c)(3).
Second, the state must reflect actual
emissions from all sources of PM10 in
the inventory. Third, the state should
report the emissions inventory in the
form of the PM10 standard it is intended
to address, e.g., in tons or pounds per
day to be consistent with the averaging
period of the 24-hour PM10 NAAQS.15
A state must meet similar CAA
section 172(c)(3) requirements in the
projected attainment year inventory for
the most expeditious year in which the
state can show attainment of the PM10
standard in the modeled attainment
demonstration portion of the
nonattainment plan. At a minimum, the
state must choose an attainment year
consistent with the outermost
applicable deadline required by CAA
section 188(c). As with the baseline year
inventory, the state must reflect
emissions from all sources of PM10 in
this inventory and report them in the
form of the PM10 standard. In addition,
the attainment year inventory must be
consistent with the source categories
and level of detail reported by the state
in the base year inventory.
Future attainment year and related
baseline emissions inventories must
reflect the most recent population,
employment, travel and congestion
estimates for the area. In this context,
‘‘baseline’’ emissions inventories refer
to emissions estimates for a given year
and area that reflect rules and
regulations and other measures that are
already adopted in a state’s EPA
approved SIP and assumed within the
attainment demonstration. Future
14 See
15 See
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81 FR 58027–58032.
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baseline emissions inventories are
necessary to show the projected
effectiveness of SIP control measures
designed to result in attainment by the
applicable attainment year. Both the
base year and future year, baseline and
attainment inventories are necessary
inputs to any modeling or other
analyses required to demonstrate
attainment of the PM10 standard, as
required by section 189(a)(1)(B).
2. Summary of State’s Submission
The West Pinal County PM10 Plan
includes a base year (2008) inventory,
and future year (2018) baseline and
attainment emissions inventories for
direct PM10 in the West Pinal County
area. The State provided documentation
for the emissions inventories in Chapter
5 (‘‘Annual Emissions Inventory’’) of the
West Pinal County PM10 Plan and its
two-part Appendix B (‘‘Pinal County
PM10 Nonattainment Area Emissions
Inventories for 2008 and 2018 Base
Years and Design Days’’, and its
supporting ‘‘Exhibits’’).16 The emissions
inventories are provided in two parts,
one representing windblown PM10
emissions on high-wind days (including
both entrained dust and windblown
dust from human activities), and the
second representing PM10 emissions on
low-wind days (including dust due to
human activity that stagnates near its
point of origin). The State presents the
annual emissions inventories on a tons
per year basis that it later converts to a
tons or pounds per day basis for use
within the attainment demonstration
modeling for the 24-hour NAAQS at
issue.
The 2018 attainment year emissions
inventories reflect State of Arizona and
Pinal County rules adopted
concurrently with the West Pinal
County PM10 Plan in late 2015.17 The
Plan’s emissions reductions are based
on continuing implementation of
existing Federal controls along with
new state and local control measures
submitted with the Plan. The 2008 base
year and projected 2018 baseline and
attainment year inventories use the most
recent EPA-approved mobile source
emissions model at the time the plan
was developed, MOVES2014, for
estimating on-road motor vehicle
emissions.18 Future emissions forecasts
in the West Pinal County PM10 Plan,
particularly on-road mobile source
emissions, are based primarily on
16 As needed, we will refer to the primary
document as ‘‘Appendix B’’ and the secondary
document as ‘‘Appendix B-Exhibits.’’
17 Please refer to Appendices G, H, and I, West
Pinal County PM10 Plan for rule adoption
information.
18 Appendix B, 62.
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demographic and economic growth
projections provided by Arizona
Department of Administration and the
Maricopa Association of Governments
(MAG).19
In general, the term ‘‘point sources’’
typically refers to permitted facilities
that have one or more identified and
fixed pieces of equipment and
emissions points. ‘‘Area sources’’
typically consist of widespread and
numerous smaller emissions sources,
such as small permitted facilities and
households. The ‘‘mobile sources’’
category refers to vehicles and is
typically divided into two major
subcategories, ‘‘on-road’’ and ‘‘nonroad’’ mobile sources. On-road mobile
sources include light-duty automobiles,
light-, medium-, and heavy-duty trucks,
and motorcycles. In addition to tailpipe,
brake, and tire wear, on-road mobile
emissions estimates for PM10 also
include re-entrained dust from vehicles
driven on paved and unpaved roads.
Non-road mobile sources include
aircraft and related support vehicles,
locomotives, construction equipment,
agricultural equipment, mobile
equipment, and recreational vehicles.
In the West Pinal County PM10 Plan,
the State based the point source
emissions for the 2008 base year
emissions inventory on reported data
from facilities using the permit file
reporting programs of the Pinal County
Air Quality Control District (PCAQCD).
Area sources, as noted above, include
smaller emissions sources distributed
across the nonattainment area. ADEQ
estimated emissions for area sources
using established inventory methods,
including publicly available emissions
factors and activity information. The
State derived activity data from national
survey data, such as the Energy
Information Administration or from
local sources and PCAQCD databases.
Emissions factors used for the estimates
come from many sources, such as
facility and equipment source tests,
compliance reports, and the EPA’s
compilation of emissions factors
document known as ‘‘AP–42.’’
ADEQ calculated the 2008 base year
on-road emissions inventories in the
West Pinal PM10 Plan using the
MOVES2014 model and a back-casting
of 2015 modeling of vehicle travel
activity data provided by MAG.20 ADEQ
estimated emissions inventories for nonroad equipment using the EPA’s
NONROAD Model, including
construction and mining equipment,
industrial and commercial equipment,
19 West Pinal County PM
10 Plan, 27–28, Table 3–
3; Appendix B, 120, 132, and 132 at footnote 97.
20 Appendix B, 62–75.
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lawn and garden equipment,
agricultural equipment, and recreational
vehicles.21 Locomotive emissions were
estimated from EPA published emission
factors and local track-mileage, train
speed, and throughput data.22 The State
developed aircraft and related ground
support vehicle emissions estimates in
conjunction with activity data from
local airports in the region.
As described previously, the State
grouped direct PM10 emissions
estimates in the West Pinal County PM10
Plan into two general categories and
emissions inventories, windblown dust
and human activity-based emissions; 23
we present these inventories in Tables
1 and 2, respectively. In general,
emission inventories can be broken into
four basic categories: Stationary sources,
area sources, non-road sources and
mobile sources. Instead of a summary
emissions inventory consisting of these
four general categories, ADEQ provided
a more detailed 2008 base year
emissions inventory. In some cases, a
source category will appear in both
emissions inventories and tables. For
example, an unpaved road and an
agricultural field will emit PM10 when
wind speeds become high enough to
pick up and carry disturbed earth, as
well as due to vehicle and equipment
traffic on the unpaved road or
agricultural activity in a field, such as
harvesting or tilling.
TABLE 1—WEST PINAL COUNTY PM10
PLAN, WINDBLOWN DUST/FUGITIVE
EMISSIONS INVENTORY
[Tons per year]
Source category
Developed Urban Lands .............
Developed Rural Lands ..............
Unpaved Roads ..........................
Cleared Areas .............................
Residential Construction .............
Dairies .........................................
CAFOs ........................................
Desert Shrubland ........................
Agriculture ...................................
Commercial Construction ...........
Other ...........................................
Site Development .......................
2008
base year
200.7
1,959.7
4,688.6
398.1
1,302.4
449.6
273.7
38,276.7
19,510.1
686.4
4,243.9
858.7
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out into permitted sources and fuel
combustion. Area sources are
disaggregated into several source
categories: Fires, open burning, unpaved
parking, and construction sites and
activities. Agricultural sources are also
disaggregated into several source
categories: on field harvesting, on field
tilling, confined animal feed operations
(CAFOs), and dairies. In contrast,
mobile sources are included within the
‘‘unpaved roads’’ and ‘‘paved roads’’
source categories. Each of these two
source categories aggregate direct
(vehicle exhaust, tire and brake wear)
and fugitive PM10 emissions from motor
vehicles on unpaved and paved roads.
Finally, nonroad equipment and
railroad emissions are assigned to their
own respective source categories.
TABLE 2—WEST PINAL COUNTY PM10
PLAN,
HUMAN
ACTIVITY-BASED
EMISSIONS INVENTORY
[Tons per year]
Source category
2008
base year
Ag Fields—Harvesting ................
Ag Fields—Tilling ........................
CAFOs ........................................
Paved Road * ..............................
Unpaved Road—All Road
Types * ....................................
Fuel Combustion ........................
Fires ............................................
Open Burning .............................
Nonroad ......................................
Railroad ......................................
Construction ................................
Dairy ...........................................
Permitted Sources ......................
Unpaved Parking ........................
312.9
2,540.3
2,614.3
1,180.7
45,127.8
28.3
19.9
13.6
121.3
85.9
12,955.3
186.6
781.3
251.5
Total .....................................
66,219.7
Source: West Pinal County PM10 Plan,
Table 5–3; Appendix B, Tables 5–31, 5–33.
* Paved and Unpaved Road emissions estimates include direct vehicle emissions and fugitive dust emissions from vehicle reentrainment.
Tables 1 and 2 provide a summary of
the West Pinal County 2008 base year
direct PM10 emissions in tons per year.
Appendix B, Chapters 3 and 5 also
provide source category estimates in a
pounds per day format consistent with
the 24-hour PM10 NAAQS. Where
Total .....................................
72,848.6 appropriate, within the attainment
Source: West Pinal County PM10 Plan, demonstration, ADEQ used these daily
estimates or developed more focused
Table 5–3; Appendix B, Tables 5–31, 5–33.
daily emissions estimates to provide the
Table 2 presents ADEQ’s direct PM10
basis for the control measure analysis
emissions inventory related to human
and the modeled attainment
activity. Stationary sources are broken
demonstrations in the West Pinal
County PM10 Plan.24 Within the
21 Appendix B, 87–90. EPA NONROAD Model,
windblown PM10 emissions inventory,
Version 2008a, released July 2009.
the largest source after desert shrubland
22 Appendix B, 96.
23 Tables 5–1, 5–2, and 5–3, West Pinal County
PM10 Plan.
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is agricultural emissions. Within the
human activity-based emissions
inventory, the largest source is unpaved
roads, followed by construction fugitive
emissions.
3. The EPA’s Review of the State’s
Submission
We have reviewed the 2008 base year
emissions inventory for direct PM10 in
the West Pinal County PM10 Plan and
emissions inventory estimation
methodologies used by ADEQ for
consistency with CAA requirements and
EPA guidance. We address the State’s
analysis for PM10 precursors in Section
III.B.
First, we find that although the 2008
base year inventory reports annual PM10
emissions estimates, the Plan also
provides and uses daily emissions
estimates within the attainment
demonstration modeling and the related
modeling domain micro-emissions
inventories; therefore, the Plan is
consistent with the requirement that
ADEQ must use an emissions inventory
in a form consistent with the 24-hour
PM10 standard.25 ADEQ has provided
adequate documentation explaining
how it calculated the 2008 base year
emissions estimates, both as annual and
daily inventories.26
Second, we find that the 2008 base
year emissions inventory in the West
Pinal County PM10 Plan used emissions
models, emission factors, and
methodologies for estimating PM10
emissions that were accurate and
appropriate to the time that the Plan
was written. Also, the 2008 base year
inventory for direct PM10 is
comprehensive in scope and coverage.
Therefore, the submitted emissions
inventory represents a comprehensive,
accurate, and current inventory of actual
emissions of direct PM10 during that
year in the West Pinal County Area.
Third, we find that ADEQ’s selection
of 2008 for the base year emissions
inventory is appropriate because it is
chosen from one of the three years,
2006–2008, in which the area was
designated nonattainment. The 2008
emissions inventory is representative of
the sources of direct PM10 pollution
contributing to exceedances of the PM10
NAAQS that caused the area to be
designated nonattainment.
Consequently, the EPA is proposing to
approve the 2008 base year emissions
inventory for direct PM10 in the West
25 As discussed in Section III.G Motor Vehicle
Emissions Budgets and Transportation Conformity,
an annual emissions inventory introduces
difficulties with determining and presenting a
motor vehicle emissions budget.
26 Chapter 5 and Appendix B of the West Pinal
County PM10 Plan.
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Pinal County PM10 Plan as meeting the
requirements for a base year inventory
set forth in CAA section 172(c)(3).
B. PM10 Precursors
1. Statutory and Regulatory
Requirements
Section 189(e) of the Act requires that
the control requirements for major
stationary sources of direct PM10 also
apply to major stationary sources of
PM10 precursors, except where the
Administrator determines that such
sources do not contribute significantly
to PM10 levels that exceed the standard
in the area. While CAA section 189(e)
expressly requires control of precursors
from major stationary sources, subpart 4
and other CAA provisions collectively
require the control of direct PM10 and
PM10 precursors from all types of
sources (i.e., stationary sources, area
sources and mobile sources) as may be
needed for the purposes of
demonstrating attainment as
expeditiously as practicable in a given
nonattainment area.27
The provisions of subpart 4 of part D,
title I of the CAA do not define the term
‘‘precursor’’ for purposes of PM10, nor
do they explicitly require the control of
any specific PM precursor. The statutory
definition of ‘‘air pollutant’’ in CAA
section 302(g), 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.’’ EPA has
identified sulfur dioxide (SO2), oxides
of nitrogen (NOX), volatile organic
compounds (VOC), and ammonia (NH3)
as precursors to the formation of PM.28
Accordingly, a state must include
emissions of direct PM emissions and
these four precursors in emissions
inventories and must control emissions
from sources of all of these pollutants,
unless the state demonstrates to EPA’s
satisfaction that control of one or more
of these pollutants is not needed for
expeditions attainment of the NAAQS
in the nonattainment area at issue.
2. Summary of the State’s Submission
Appendix B, Exhibit BXVI contains
ADEQ’s demonstration that emissions of
SO2, NOX, and NH3 from existing
sources in the West Pinal County
nonattainment area do not contribute
significantly to PM10 levels that exceed
the NAAQS. For this analysis, ADEQ
estimated the impact of these three PM10
27 See CAA requirements for states to demonstrate
attainment ‘‘as expeditiously as practicable,’’ CAA
section 188(c)(1) and section 172(a)(1).
28 See 81 FR 58010, 58018.
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precursors on PM10 concentrations at
two sites, Cowtown (CWT) and Pinal
County Housing (PCH), using ‘‘worst
impact day monitored data’’ from a
year-long chemical mass balance
characterization (CMBC) study (Desert
Southwest Coarse Particulate Matter
Study) and emissions data from the
2008 National Emission Inventory
(NEI).29 ADEQ evaluated these data to
determine which, if any, source
categories had precursor emissions that
contribute more than 5 micrograms per
cubic meter (mg/m3) on specific design
days. 30
Appendix B, Exhibit BXVI, Table
BXVI–1 provides the maximum particle
mass concentration and chemical
composition (i.e., crustal, organic
material, nitrate, sulfate, ammonium,
other species, and unidentified particle
fractions) measured during the CMBC
study for CWT and PCH. ADEQ then
calculated the percentage of each
chemical constituent to the summed
total of the chemical constituent parts.
ADEQ assumed the design days for each
monitor had the same relative chemical
composition as the ‘‘worst impact day’’
identified in the CMBC study. The State
calculated design day concentrations for
each chemical constituent by
multiplying the study-derived
percentages by a design day
concentration for CWT (244.5 mg/m3)
and PCH (178.0 mg/m3). The CMBC
study estimated that summed nitrate,
sulfate, and ammonium impacts on the
CWT and PCH monitors were 3.4
percent and 4.0 percent, respectively.
These percentages suggest that 8.4 mg/
m3 and 7.2 mg/m3 of the design day
ambient PM10 concentrations at the
CWT and PCH monitors resulted from
emissions of the three PM10 precursors
examined.
Next, ADEQ processed Pinal County
2008 EPA NEI reported emissions for
NOX, SO2, and NH3 to determine the
percent contribution of each source
sector to the total emissions of these
pollutants for the county. 31 ADEQ
apportioned the precursor
concentrations derived above to
individual source sectors based on the
relative contribution of each sector to
the annual emission inventory. Based
29 Clements, A.L., Fraser, M.P., Upadhyay, N.,
Herckes, P., Sundblom, M., Lantz, J., and Solomon,
P.A., ‘‘Chemical characterization of coarse
particulate matter in the Desert Southwest—Pinal
County Arizona, USA’’, Atmospheric Pollution
Research, 5 (2014) 52–61.
30 ADEQ focused their attainment demonstration
on a set of ‘‘design days’’ and monitors that have
experienced, or are conducive to, the highest
concentrations. See EPA TSD, p. 11. Two design
days were examined in ADEQ’s PM10 precursor
demonstration.
31 Appendix B, Exhibit BXVI, Table BXVI–2.
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on this analysis, no precursor emissions
from any source category exceeded the
5 mg/m3 threshold.32 The largest
contributing source category was ‘‘Onroad Mobile,’’ contributing less than 3.5
mg/m3 of PM10 from precursor emissions
to either monitor on the design days.
3. The EPA’s Review of the State’s
Submission
We identified several issues with the
analysis that ADEQ presented. First,
SO2, NOX, VOC, and ammonia are
precursors to the formation of PM10.
ADEQ does not address VOC emissions
in its analysis; therefore, we cannot
evaluate whether sources of VOC
emissions contribute significantly to
PM10 levels that exceed the NAAQS in
the West Pinal County PM10
nonattainment area.
Second, it is unclear whether the
chemical composition values presented
in Appendix B, Exhibit BXVI, Table
BXVI–1 reflect one maximum day
sample, or the maximum chemical
composition measured for each
individual component during the entire
CMBC study. If the latter approach was
used, then the resulting percentages
would not reflect percentages measured
on any actual exceedance day and could
overrepresent or underrepresent the
various chemicals when compared to
actual exceedance days. If the chemical
composition values represent one
maximum day sample, then: (a) The
individual components listed in Table
BXVI–1 when totaled together should
equal that day’s total mass, which they
do not; and (b) this would only
represent a single day—therefore, a
single type of exceedance day. ADEQ
modeled two meteorological scenarios
causing exceedances, high wind
conditions and stagnant or low wind
conditions. The emission sources
affecting the PM10 composition would
vary between these two scenarios,
making use of a single maximum value
at each site for each chemical
component likely insufficient.
Therefore, ADEQ’s approach of
assuming the chemical composition of
the two design days match those
reported in the study likely does not
address all conditions affecting
nonattainment for the area.
Third, ADEQ applied the 5 mg/m3
threshold from the Serious PM10
nonattainment area addendum to the
General Preamble.33 The Serious area
addendum states that, for purposes of
evaluating best available control
measures (BACM), a source category
32 Appendix
33 Appendix
B, Exhibit BXVI, Table BXVI–3.
B, Exhibit BXVI, BXVI–2. See 59 FR
at 42011.
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will be presumed to contribute
significantly to a violation of the
NAAQS if its PM10 impact at the
location of the expected violation would
exceed 5 mg/m3. This guidance is not
precursor guidance and was intended to
apply to the total impact of a source
category (including direct PM and
precursor emissions). It is not clear from
the State’s submission why the
application of this threshold to the
impact of precursor emissions from
individual source categories is an
appropriate method of evaluating the
significance of PM10 precursor
emissions for the West Pinal County
PM10 nonattainment area.34
Finally, ADEQ used an annual
inventory to partition the source
category contribution to PM10. High
wind affected days would likely have a
different composition of sources than
what would be reflected in an annual
inventory, potentially by a substantial
margin. ADEQ did not address this
issue, and used the annual inventory
composition to represent all exceedance
days.
The State has not adequately shown
that PM10 precursors do not contribute
significantly to concentrations above the
NAAQS in the West Pinal County PM10
nonattainment area. As described
elsewhere in this notice, due to the
deficiencies with the State’s precursor
analysis, the State has not shown that it
was unnecessary to regulate emissions
of precursors in its RACM and modeled
attainment demonstration. As explained
in Section III.C., the State has only
evaluated sources of direct PM
emissions within the West Pinal County
PM10 Plan. The EPA anticipates that
ADEQ could develop an improved
precursor analysis for the area, and this
analysis may ultimately confirm that it
is not necessary to regulate one or all of
the PM10 precursors; however, we find
that the precursor analysis submitted
with the Plan does not provide a
sufficient basis for that conclusion.
In conclusion, because of the
omissions and uncertainties in ADEQ’s
PM10 precursor analysis, we are unable
to determine whether precursor
emissions contribute significantly to
PM10 levels that exceed the NAAQS in
the West Pinal County nonattainment
area. Consequently, we are proposing to
disapprove the precursor demonstration
in the West Pinal County PM10 Plan
because the demonstration is inadequate
to show that emissions reductions from
34 For more recent guidance on precursor
significance, see Memorandum from Scott Mathias,
Acting Director, Air Quality Policy Division and
Richard Wayland, Director, Air Quality Assessment
Division, ‘‘Fine Particulate Matter (PM2.5) Precursor
Demonstration Guidance’’ (May 30, 2019).
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all PM10 precursors do not contribute
significantly to PM10 levels exceeding
the NAAQS, as required by CAA
Section 189(e). As explained in section
III.C, the deficiencies in the State’s
precursor analysis mean that the State
failed to establish in its RACM/RACT
analysis that it was unnecessary to
regulate PM10 precursor emissions.
C. Reasonably Available Control
Measures Demonstration
1. Statutory and Regulatory
Requirements
CAA section 172(c)(1) requires that
each attainment plan provide for the
implementation of all RACM/RACT as
expeditiously as practicable (including
such reductions in emissions from
sources in the area through
implementation of reasonably available
control technology) and for attainment
of the NAAQS. Consistent with section
189(a)(1)(C), each state with a Moderate
PM10 nonattainment area is required to
submit provisions to assure
implementation of reasonably available
control measures no later than 4 years
after the date of designation of the area.
Taken together, these CAA provisions
require that Moderate area attainment
plans must provide for the
implementation of RACM and RACT in
the nonattainment area as expeditiously
as practicable but no later than 4 years
after designation.
Section 189(a)(1)(B) of the CAA
requires states to demonstrate
attainment of the PM10 standard by the
applicable attainment date (or
demonstrate that attainment by such
date is impracticable) and Section
188(c)(1) requires that the attainment
date for a Moderate area shall be as
expeditiously as practicable, but no later
than the end of the sixth calendar year
after the year of the nonattainment
area’s designation.
To address this requirement to adopt
all RACM/RACT and meet the PM10
NAAQS as expeditiously as practicable,
states should consider all potentially
reasonable control measures for source
categories in the nonattainment area to
determine whether they are reasonably
available for implementation in that
area and whether they would, if
implemented individually or
collectively, advance the area’s
applicable attainment date by one year
or more.35 Any measures that are
necessary to meet these requirements
that are not either federally
promulgated, or part of the state’s SIP,
must be submitted in enforceable form
35 44 FR 20372 (April 4, 1979) and 57 FR 13498
(April 16, 1992).
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as part of the state’s nonattainment plan
SIP submission for the area.
The EPA has provided guidance
interpreting the RACM requirement in
the General Preamble for the
Implementation of the Clean Air Act
Amendments of 1990 (‘‘General
Preamble’’). This guidance includes the
following elements and concepts: A
recommended list of potential PM10
measures for states to consider; 36 an
emphasis on a state’s evaluation of the
technological and economic feasibility
of potential control measures to
determine if such measures are
reasonably available for implementation
in a given nonattainment area; an
expectation that the state will provide a
reasoned explanation for a decision not
to adopt a given control measure,
including a review of any control
measures recommended to the state
during public comment or public
hearing; and, a discussion that in some
cases partial implementation of an
emissions reduction program may be
considered RACM when full
implementation would be infeasible
within the given Moderate area
timeframe.37
2. Summary of the State’s Submission
For the West Pinal County PM10 Plan,
ADEQ worked through a process to
identify and evaluate potential RACM/
RACT that could contribute to
expeditious attainment of the PM10
NAAQS in the West Pinal County
nonattainment area. Chapter 6 of the
West Pinal County PM10 Plan provides
an overview and description of the
Plan’s constituent control measures.
ADEQ’s RACM/RACT analysis for the
PM10 standard is described in Appendix
F—RACM Analysis for the West Pinal
County PM10 Nonattainment Area
(‘‘Appendix F’’). Appendix F contains
summary analyses of potential control
measures for emissions reduction
opportunities, as well as the economic
and technological feasibility and
comparability with control requirements
in other states and localities.
As a first step in the RACM/RACT
analysis, ADEQ prepared a detailed
inventory of direct PM10 emissions
sources to identify source categories
from which emissions reductions would
contribute to attaining the PM10
standard.38 In this analysis, ADEQ
identified point sources, unpaved roads
and agriculture on tribal land, dairy
operations, nonroad vehicles,
residential fuel combustion, and open
burning as insignificant sources of
36 57
FR 18070.
FR 13540, 13541.
38 Appendix F, Chapters 2 and 3.
37 57
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emissions in the area.39 Then, ADEQ
identified agricultural operations,
confined animal feeding operations,
fugitive dust from cleared area and
unpaved parking lots, construction
fugitive dust, and re-entrained dust from
paved and unpaved roads as significant
sources in the nonattainment area and
determined a list of available control
measures. ADEQ determined that a
source category was significant if those
sources contributed more than 5 mg/m3
on a 24-hour basis on a given design
day. Conversely, ADEQ determined that
source categories contributing less than
the 5 mg/m3 threshold were
insignificant; furthermore, ADEQ
determined these insignificant sources
would not advance attainment of the
NAAQS, given their small collective
contribution to nonattainment.40
Finally, ADEQ evaluated the efficacy,
cost, and technical feasibility of these
identified control measures within the
nonattainment area.41 As part of this
review, ADEQ also compared the
control requirements of its proposed
rules with those requirements in other
PM10 nonattainment areas or similar
state and local provisions.42 ADEQ did
not identify sources or analyze potential
RACM/RACT for PM10 precursors
because it concluded that such
precursors did not contribute
significantly to a violation of the
NAAQS.
With this process, ADEQ attempted to
evaluate and analyze the universe of
potential RACM/RACT level controls for
sources of direct PM10 emissions and
identify the subset of control measures
that were available to include within the
West Pinal County PM10 Plan. ADEQ
identified a set of control measures that
it determined would be sufficient to
enable the area to attain by December
31, 2018, and additional controls that it
determined were not necessary for
attainment or RFP to serve as
contingency measures.43 ADEQ based
this conclusion on: (1) The practical
feasibility of adopting control measures
over the latter half of 2015 with the
State’s desired implementation date of
no later than January 1, 2016; and (2)
the ability of these control measures to
produce immediate emissions
reductions and contribute to attainment
of the PM10 NAAQS by 2018.44 As
39 Appendix
F, 4–12.
F, Chapter 2 and Table 1.
41 Appendix F, Chapters 2–4.
42 Appendix F, Chapter 4; Exhibit F–I, Available
Measures; Exhibit F–II, Construction Comparison;
Exhibit F–III, Agricultural Comparison; and, Exhibit
F–IV, Fugitive Dust Comparison.
43 West Pinal County PM
10 Plan, Chapter 7; Table
7–4; Appendix D, Table D5–1.
44 Appendix F, 29, 47, 51.
discussed earlier, the State submitted
the following control measures with the
West Pinal County PM10 Plan: The
AgBMP Rules for Pinal County, the
Pinal County Fugitive Dust Rule, and
the Pinal County Construction Dust
Rule. ADEQ relied only on the following
portions of the AgBMP Rules for Pinal
County to meet the RACM/RACT
requirements and demonstrate
attainment of the PM10 standard:
AgBMP rule R18–2–610 and –610.03,
commercial farms; AgBMP rule R18–2–
611 and –611.03, commercial animal
operations (except for dairy operations);
and R18–2–612 and –612.01, irrigation
districts.45
ADEQ did not provide a complete or
systematic analysis of whether the
control measures it did not adopt based
on concerns about a lack of immediate
emission reduction effect, if taken
together, would advance the area’s
attainment date. Nonetheless, ADEQ did
adopt those control measures,
implemented them over the 2016–2018
timeframe, and allocated them to serve
as contingency measures in the Plan.
ADEQ designated the portion of the
AgBMP Rules for Pinal County
applicable to dairy operations (R18–2–
611 and –611.03), along with the Pinal
County Fugitive Dust Rule and the Pinal
County Construction Dust Rule, as
contingency measures because these
rules provided additional emissions
reductions not relied upon within the
Plan’s attainment demonstration.46
3. The EPA’s Review of the State’s
Submission
As described above, ADEQ evaluated
a wide range of potentially available
measures for the West Pinal County
PM10 Plan. ADEQ identified portions of
the AgBMP Rules for Pinal County as
RACM/RACT and the State adopted
them to provide for attainment of the
PM10 standard.47 The remaining
adopted control measures, some of
which were identified as significant
sources and potential RACM/RACT,
were assigned to provide for
contingency measures within the
Plan.48 In sum, all source categories
identified as significant were covered by
controls either as a control measure for
attainment, or as contingency measures,
and implemented over the 2016–2018
timeframe. As has been confirmed by
subsequent monitoring data, however,
40 Appendix
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45 West
Pinal County PM10 Plan, Chapters 6 and
7.
46 West Pinal County PM
10 Plan, Chapter 6;
Chapter 7, Table 7–4.
47 West Pinal County PM
10 Plan, Chapters 6 and
7.
48 West Pinal County PM
10 Plan, Chapter 6;
Chapter 7, Table 7–4.
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these adopted control measures were
insufficient to attain the PM10 NAAQS
by the applicable attainment date, in
part because the State overestimated the
effectiveness of the RACM/RACTdesignated adopted controls. As an
example, ADEQ assumed high and
insufficiently conservative compliance
rates for agricultural operations that had
either no previous experience
implementing control measures, or little
to no reliable documented compliance
history. We review the State’s analysis
and attainment demonstration in
Section III.D and provide detailed
discussion in the Technical Support
Document (TSD).
The Plan described the adopted
control measures and concluded that a
subset was reasonable and would
achieve the NAAQS by the attainment
date; therefore, the State concluded that
the RACM/RACT-designated subset of
adopted control measures constituted
the necessary RACM/RACT for the
area.49 The State adopted several
additional measures beyond the RACM/
RACT measures to serve as contingency
measures in the Plan. If the RACM/
RACT-designated adopted controls
actually sufficed to achieve attainment,
then these control measures could have
constituted sufficient RACM, as
additional measures beyond those
necessary for attainment need not
necessarily be considered as RACM/
RACT.50 Because the adopted controls
designated as RACM/RACT in the West
Pinal County PM10 Plan were
insufficient, however, to achieve
attainment, due in part to overestimates
of the control efficiency of these rules,
we find that the State terminated its
RACM/RACT analysis prematurely. The
control measures reserved for
contingency measures that the State did
not include as RACM/RACT should
have been included and justified as
RACM. Furthermore, because the State’s
determination regarding PM10
precursors failed to demonstrate that
precursors do not contribute
significantly to a violation of the
NAAQS, the State remains obligated to
demonstrate that additional PM10
precursor control measures are not
required RACM/RACT.
Despite the RACM/RACT-designated
rules and contingency measures
adopted and implemented by the State,
we find that the State failed to adopt
RACM/RACT sufficient to achieve the
PM10 NAAQS, due in part, to
overestimating the control effectiveness
49 Appendix
F, Chapter 4.
81 FR 58010, 58035. Although such
controls should be evaluated to determine if their
adoption could advance attainment.
50 See
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of these RACM/RACT control measures.
Our conclusion is confirmed by the
failure of the Plan’s adopted and
designated measures to result in
attainment of the PM10 NAAQS by the
applicable attainment date of December
31, 2018. Because the adopted controls
were insufficient to meet the PM10
NAAQS by the attainment date, and the
State excluded source categories,
including sources of precursors, from its
RACM/RACT demonstration without
sufficient justification, we propose to
disapprove the RACM/RACT
demonstration in the West Pinal County
PM10 Plan and determine that the Plan
does not provide for the implementation
of all RACM/RACT as required by CAA
section 172(c)(1) and section
189(a)(1)(C).
D. Attainment Demonstration
1. Statutory and Regulatory
Requirements
Section 189(a)(1)(B) of the CAA
requires that a plan for a Moderate PM10
nonattainment area include a
‘‘demonstration (including air quality
modeling) that the plan will provide for
attainment [of the PM10 NAAQS] by the
applicable attainment date.’’ An
attainment demonstration consists of
several elements including technical
analyses, such as base year and future
year modeling, to locate and identify
sources of emissions that are
contributing to violations of the PM10
NAAQS within the nonattainment area
(i.e., analyses related to the emissions
inventory for the nonattainment area
and the emissions reductions necessary
to attain the standard). Section 188(c)(1)
of the CAA requires Moderate areas to
meet the PM10 standard as expeditiously
as practicable, but no later than the
sixth calendar year from the area
designation.
In addition to reviewing the
attainment demonstration modeling and
related analyses, we evaluate the Plan’s
control strategy and the efficacy of the
Plan’s adopted controls to meet the
PM10 NAAQS by the applicable date.
2. Summary of the State’s Submission
ADEQ applied a form of proportional
roll back and dispersion modeling using
a micro-emissions inventory method to
model attainment of the PM10 NAAQS.
ADEQ modeled two meteorological
scenarios causing ambient air values in
excess of the 24-hour PM10 NAAQS of
150 mg/m3, high wind conditions and
stagnant or low wind conditions, at a
representative subset of the monitoring
sites in the nonattainment area.51 Under
51 West
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1355
‘‘stagnation’’ conditions, wind speeds
are typically below 3 mph and particles
accumulate in the air without any
meteorological reprieve. Under ‘‘high
wind’’ conditions, elevated wind speeds
(e.g., over 12 mph) generate dust from
disturbed soil surfaces, elevating PM10
concentrations. Each selected
monitoring site in each modeling
scenario had design day specific microemissions inventories consistent with
the chosen areal modeling domain and
application. ADEQ calculated the 2008
Base, 2018 Base, and 2018 Attainment
micro-emissions inventories for the
given requirements of the modeling
application at the respective monitoring
site domain and meteorological day
scenario.
The State’s attainment demonstration
approach is described in the Plan within
the following documents: Chapter 7,
‘‘Attainment Demonstration and
Reasonable Further Progress’’;
Appendix A, ‘‘Pinal County PM
Inventory Preparation Plan’’ (‘‘IPP’’);
Appendix B, ‘‘Pinal County PM10
Nonattainment Area Emissions
Inventories for 2008 and 2018 Base
Years and Design Days’’ (‘‘Modeling
EI’’); Appendix C, ‘‘Pinal County PM10
Nonattainment Area Source
Apportionment Modeling for 2008 and
2018 Base Scenario Design Days’’
(‘‘Modeling TSD’’); and, Appendix D,
‘‘Pinal County PM10 Nonattainment
Area 2018 Attainment Demonstration
and Controlled Emissions Inventories.’’
The West Pinal County PM10 Plan
discusses the control strategy within
Chapter 6 of the Plan and in more detail
within Appendix D of the Plan.
a. Modeling
As noted, the West Pinal County PM10
Plan’s attainment demonstration
considers two specific problems
contributing to nonattainment of the
PM10 standard in West Pinal County: (1)
PM10 emissions from windblown dust
and human activity on days with
elevated wind speeds; and (2) PM10
emissions from human activity,
particularly on days with very low wind
or ‘‘stagnant’’ meteorological conditions.
• ADEQ developed a high wind day
scenario for Cowtown, Maricopa, Pinal
County Housing, and Stanfield monitors
and surrounding area micro-emissions
inventories. Each monitor has its own
two domain micro-emissions inventory
for modeling: High wind hours/
windblown dust; and, low wind hours/
activity-based emissions. The high wind
scenario used a proportional rollback
approach that accounts for the timing
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and geographic location of emissions
contributing to NAAQS exceedances.52
• ADEQ developed a stagnation day
scenario for Cowtown, Pinal County
Housing, and Stanfield monitors and
surrounding area micro-emissions
inventories. The stagnant day scenarios
used dispersion modeling from the
American Meteorological Society
(AMS)/EPA Regulatory Model
(AERMOD). ADEQ chose design days
from the fall season, September through
November 2008 for this analysis.
b. Control Strategy for Attainment
ADEQ relied on the following
portions of the AgBMP Rules for Pinal
County to provide for attainment of the
PM10 standard: R18–2–610 and –610.03,
commercial farms; AgBMP rule R18–2–
611 and –611.03, commercial animal
operations (except for dairy operations);
and, R18–2–612 and –612.01, irrigation
districts.53 Tables 3 and 4 show the
annual nonattainment area emissions
inventories for the 2018 baseline
estimate and the 2018 attainment
estimate by source category and the
control strategies’ predicted emissions
reductions. Within the windblown
fugitive dust emissions inventories,
ADEQ predicted almost all the emission
reductions, 93 percent, to come from
soil stabilization control measures on
agricultural land. Within the activitybased emissions inventories, ADEQ
predicted most of the emission
reductions, 87 percent, to come from
control measures applied to unpaved
road operations on private agricultural
land and canal roads; the remainder of
predicted emission reductions come
from control measures to reduce PM10
emissions from on-field agriculture and
animal feeding operations. As noted, the
regulatory vehicle for these emissions
reductions is the AgBMP rule provisions
the State relied on to provide for
attainment of the PM10 standard and to
implement RACM/RACT in the area.
TABLE 3—WINDBLOWN DUST/FUGITIVE EMISSIONS, 2018 BASE AND ATTAINMENT EMISSIONS INVENTORIES WITH
ESTIMATED EMISSION REDUCTIONS
[tpy]
Source category
Base 2018
Attainment 2018
Emission reductions
Developed Urban Lands ..............................................................................................
Developed Rural Lands (low density) .........................................................................
Unpaved Roads ...........................................................................................................
Cleared Areas ..............................................................................................................
Residential Construction ..............................................................................................
Dairies ..........................................................................................................................
CAFOs .........................................................................................................................
Desert Shrubland .........................................................................................................
Agriculture ....................................................................................................................
Commercial Construction ............................................................................................
Other ............................................................................................................................
Site Development ........................................................................................................
248.1
1,959.7
4,653.0
457.0
837.5
449.6
155.2
........................
19,510.1
441.4
4,243.9
552.2
248.1
1,959.7
3,803.1
457.0
837.5
449.6
125.3
............................
7,122.0
441.4
4,243.9
552.2
....................................
....................................
849.9
....................................
....................................
....................................
29.9
....................................
12,388.1
....................................
....................................
....................................
Total ......................................................................................................................
33,507.7
20,239.8
13,267.9
Source: West Pinal County PM10 Plan, Table 5–3; Appendix B, Tables 5–31, 5–32, 5–33, 5–34.
TABLE 4—ACTIVITY BASED EMISSIONS, 2018 BASE AND ATTAINMENT EMISSIONS INVENTORIES WITH ESTIMATED EMISSION
REDUCTIONS
[tpy]
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Source category
Base 2018
Attainment 2018
Emission reductions
Ag—Harvesting ............................................................................................................
Ag—Tilling ....................................................................................................................
CAFOs .........................................................................................................................
Paved Road * ...............................................................................................................
Unpaved Road * ...........................................................................................................
Fuel Combustion ..........................................................................................................
Fires .............................................................................................................................
Open Burning ...............................................................................................................
Nonroad .......................................................................................................................
Railroad ........................................................................................................................
Construction .................................................................................................................
Dairy .............................................................................................................................
Permitted Sources .......................................................................................................
Unpaved Parking .........................................................................................................
312.9
2,540.3
1,620.6
1,408.0
45,105.3
34.9
22.2
16.8
144.4
45.4
8,499.8
184.0
781.3
251.5
207.1
1,658.0
1,369.2
1,408.0
37,186.4
34.9
22.2
16.8
144.4
45.4
8,499.8
184.0
781.3
251.5
105.8
882.3
251.4
....................................
7,918.9
....................................
....................................
....................................
....................................
....................................
....................................
....................................
....................................
....................................
Total ......................................................................................................................
60,967.4
51,809.0
9,158.4
Source: West Pinal County PM10 Plan, Table 5–3; Appendix B, Tables 5–31, 5–32, 5–33, 5–34
* Paved and Unpaved Road emissions estimates include direct vehicle emissions and fugitive dust emissions from vehicle re-entrainment.
52 The term ‘‘rollback’’ refers to the assumption
that the PM10 concentrations are directly
proportional to emissions. To predict the ambient
effect of an emissions change, the concentration can
be scaled, or ‘‘rolled back,’’ by the same percentage
by which emissions are reduced. In ‘‘proportional
rollback,’’ each source category is rolled back
separately, since emissions from each will have a
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different level of control, and in general a different
degree of dispersion. As in simple rollback, the
ambient contribution of each individual source
category scales with its emissions. For the
‘‘weighted proportional rollback,’’ source-tomonitor distance was accounted for via an inverse
distance factor (1/d). For example, a source with
only small emissions may nevertheless have a large
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contribution to the concentration if it was very
close to the monitor. A change in a source’s
emissions causes a change in total concentration in
proportion to that source’s contribution to that
particular monitor.
53 West Pinal County PM
10 Plan, Chapters 6 and
7.
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The State adopted and preimplemented control measures to meet
the contingency measures requirement
within the Plan: The portion of the
AgBMP Rules for Pinal County
applicable to dairy operations (R18–2–
611 and –611.03), along with the Pinal
County Fugitive Dust Rule and the Pinal
County Construction Dust Rule.54 We
address the contingency measures
requirement of the Act more completely
in Section III.F, where we point out that
pre-implemented contingency measures
are not approvable under CAA section
172(c)(9). Here, we mention the control
measures, adopted and subsequently
implemented as contingency measures,
to emphasize two points: (1) Given the
shortfall in attaining the PM10 NAAQS,
these control measures designated for
contingency should have been evaluated
and designated RACM/RACT, as we
discussed in Section III.C; and (2)
despite implementing the RACM/RACT
control measures for attainment and the
designated contingency measures, the
West Pinal County area still failed to
attain the PM10 NAAQS, by a large
margin.
3. The EPA’s Review of the State’s
Submission
As previously discussed, the EPA
issued a finding that the West Pinal
County area failed to attain the PM10
NAAQS by the outermost statutory
attainment date of December 31, 2018.55
In addition to our previous regulatory
review of the air monitoring data from
2016–2018, detailed in our June 24,
2020 notice, we reviewed ambient air
monitoring data collected from 2006–
2018 to examine PM10 values over time
and recent trends over the 2016–2018
control strategy period of Plan
implementation. Our detailed review of
PM10 data is included in our TSD
provided in the docket for this proposal.
We provide two general conclusions
from our data review.
First, when considering the number of
exceedances of the PM10 standard, the
data show that the West Pinal County
monitoring sites have consistently
measured many exceedances in every
year between the start of the base year
period, 2006–2008, and in 2018, the
attainment year. While the number of
exceedances each year has generally and
gradually decreased over time, there is
no clear evidence of a sustained
decrease in recent years as ADEQ
implemented control measures. For
example, over the 2016 through 2018
period that would have been relevant to
attainment by December 31, 2018, the
annual number of exceedances of the
24-hour PM10 NAAQS ranged from 29 to
38.56 The form of the NAAQS allows for
no more than one exceedance per year,
averaged over a three year period.
Furthermore, all eight monitors in the
West Pinal County nonattainment area
showed violations of the PM10 NAAQS
as determined by their 2018 design
values.57
Second, design value trends show that
the number of expected exceedances
remain well above the PM10 NAAQS of
one exceedance per year. The high
concentrations and number of
exceedances clearly show that PM10
concentrations well above the level of
the NAAQS (150 mg/m3) continue to be
a major air quality problem in the West
Pinal County nonattainment area
despite the implementation of control
measures meant to reduce PM10 levels.
For example, the design concentration
for 2016–2018, the period in which
values should be at or under 150 mg/m3
to show attainment by 2018, is 403 mg/
m3, or 269 percent of the standard.58
TABLE 5—THREE-YEAR PM10 MONITORING DATA STATISTICS FOR THE COWTOWN AND HIDDEN VALLEY MONITORING
SITES a
3-Year period
2006–
2008
Design Concentration (μg/m3)
3-year Design Value .............
2007–
2009
916
201.2
2008–
2010
653
139.8
2009–
2011
539
86.1
1064
60.7
2010–
2012
1064
63
2011–
2013
2012–
2014
1064
75.7
521
64
2013–
2015
510
50.5
2014–
2016
2015–
2017
b 357
b 303
b 38.3
b 29.8
2016–
2018
403
32.8
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Sources: EPA AQS Quick Look Report, December 10, 2020, and EPA AQS Design Value Report, December 10, 2020. The design concentration for these sites is
the 4th highest 24-hour concentration measured over each three-year period, as detailed in Section 6.3.1 of the PM10 SIP Development Guideline, EPA–450/2–86–
001 (June 1987).
a Data collected prior to 2016 were collected from the Cowtown monitoring site; data since 2016 were collected at the Hidden Valley monitoring site, as described in
our TSD, page 6, within the docket for this rulemaking.
b The EPA’s relocation approval letter stated that the data from Cowtown and Hidden Valley would be combined to form one continuous data record for design
value calculations. Consequently, the 2014–2016 and 2015–2017 design values are each a composite data record consisting of 2014 and/or 2015 data from the
Cowtown monitoring site, and 2016 and/or 2017 data from the Hidden Valley monitoring site, as applicable.
The West Pinal County 2015 PM10
design value was 50.5 exceedances. For
the area to meet the PM10 standard by
2018, it could not have more than three
exceedances of the PM10 NAAQS across
the three years, 2016–2018, to show a
design value of 1.0 exceedances,
averaged over three years. Instead, the
Plan’s control strategy resulted in the
following number of primary
exceedances: 30 in 2016; 38 in 2017;
and 29 in 2018.59 Not only did the
Plan’s control strategy fail to produce
the effect intended in 2016, the
designated control strategy rules and
pre-implemented contingency measures
54 West Pinal County PM
10 Plan, Chapter 6;
Chapter 7, Table 7–4.
55 85 FR 37756.
56 See Table 2 in the TSD.
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failed to reduce PM10 exceedances to a
level needed to attain the PM10 standard
by December 31, 2018.
Given the ambient monitoring data
unequivocally indicate that the Plan
was insufficient to achieve attainment
by the 2018 attainment date, we do not
provide an exhaustive evaluation of the
attainment demonstration analyses in
the West Pinal County PM10 Plan.
Instead, we focused our review on two
major deficiencies that preclude our
approval of this Plan element. Our
review of these two deficiencies is
illustrative of the insufficiently
conservative analyses or assumptions
57 See
Table 1 in the TSD.
Table 3 and further discussion in Section
II.B of the TSD.
58 See
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underlying the Plan’s failed attainment
demonstration. Specifically, we
evaluated the ‘‘design days’’ ADEQ
selected to conduct the modeling
exercises and the specific design day
micro-emissions inventories and rule
control effectiveness assumptions ADEQ
made to model the Plan’s control
strategy within the 2018 attainment
modeling analyses. Next, we provide a
short summary of our review. We also
provide a more detailed review in our
TSD.
First, we find the design days that
ADEQ selected for modeling the
Cowtown monitor under stagnation
59 TSD, Table 2; EPA AQS Quick Look Report,
December 10, 2020, in the docket for this
rulemaking action.
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conditions, and several monitors under
high wind conditions, were chosen with
inconsistent criteria and/or have data
inaccuracies. In turn, these
inconsistencies and inaccuracies led to
design day concentration values that
were likely too low to address
adequately the range of exceedances
experienced in the nonattainment area.
For example, in selecting the stagnation
scenario design day for Cowtown,
ADEQ limited selection to fall 2008
(September to November) exceedance
days despite the higher PM10
concentrations and a comparable
number of exceedance days in the
spring season (March to May).
Ultimately, the selected 2008 design day
was the 68th highest out of the 137 total
low wind/stagnation exceedance days
identified by the State (i.e.,
approximately 49% of the low wind/
stagnation exceedance days had higher
concentrations than the design day
selected).60 This middle range day was
insufficiently conservative and was
inadequate to represent the attainment
issues during stagnation conditions and
to address the range and severity of
exceedances experienced at CWT.61
Second, we conclude that several data
inputs and assumptions associated with
modeling the control strategy were
unsupported, overstated, or
insufficiently conservative leading to an
overestimate of the overall efficacy of
the control strategy within the
attainment demonstration. Specifically,
in calculating the control effectiveness
of the rules in the control strategy, two
component assumptions or estimates
were the primary cause of this
overestimate: (1) Rule effectiveness, i.e.,
the percentage of compliant facilities;
and, (2) aggregate or net best
management practices (BMP) control
efficiencies. For example, we found that
despite limited or no compliance data,
the lack of compliance assistance
program efficacy figures, the lack of
automatic reporting requirements, and
little to no farm experience
implementing BMPs, ADEQ assumed
high compliance rates with the AgBMP
rule; in turn, this unjustifiably inflated
the overall control effectiveness
calculations. In addition, we found that
the domain modeling micro-emissions
inventory estimates that ADEQ derived
60 ‘‘Low wind/stagnation exceedance days’’ for
purposes of this document are the exceedance days
that remain once days identified by ADEQ as high
wind day exceedances in IPP, Appendix C, Table
C–1 are removed. See ‘‘Cowtown 2008
Exceedances.xlxs’’ in the docket for this action.
61 See Section III.B.1. of the TSD for our complete
review of design day selection for stagnation
scenario at the Cowtown monitor. Also, see Section
III.B.2 of the TSD for our complete review of design
day selection for the high wind scenario.
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from this limited BMP implementation
data were not appropriately
documented or supported and were
insufficiently conservative due to overly
optimistic or simplifying assumptions
used to aggregate BMP control efficiency
estimates, such as assuming that farms
will either choose not to operate or will
routinely implement higher cost and
higher control efficiency BMPs on high
risk days. Consequently, ADEQ assumed
farms reduced emissions from cropland
operations and unpaved roads to a
greater extent than what could be
supported by the documentation in the
Plan.62
Based on our evaluation of the design
days and modeling and control
effectiveness assumptions in the Plan,
we find that these several deficiencies
in the analyses preclude approval of the
attainment demonstration. In addition,
after reviewing past and recent PM10
data against the West Pinal County PM10
Plan’s attainment demonstration
predictions, we conclude that:
• There is no clear evidence of a
sustained decrease in the number of
exceedances in recent years as control
measures have been implemented
(2015–2018);
• PM10 concentrations well above the
level of the 24-hour PM10 NAAQS (150
mg/m3) continue to be a major air quality
problem in the West Pinal County
nonattainment area despite the
implementation of control measures
designed to reduce PM10 levels thus far;
and
• The Plan’s control strategy, whether
considered as adopted RACM/RACT or
as the entire suite of rules submitted
with the Plan, was inadequate to attain
the PM10 NAAQS by December 31,
2018, as evidenced by the ambient PM10
data.
Consequently, we propose to
disapprove the modeled attainment
demonstration in the West Pinal County
PM10 Plan because it does not meet the
requirements of CAA section
189(a)(1)(B) and section 188(c)(1).
E. Reasonable Further Progress
Demonstration
1. Statutory and Regulatory
Requirements
The requirement for RFP in PM10
nonattainment areas is specified in CAA
section 172(c)(2) and is described in the
General Preamble.63 Under CAA section
171(1), RFP is defined as meaning such
annual incremental reductions in
emissions of the relevant air pollutant as
are required under part D (‘‘Plan
62 See Section III.C. of the TSD for our complete
review of control effectiveness estimates.
63 57 FR at 13539.
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Requirements for Nonattainment
Areas’’) of the CAA or as may
reasonably be required by the EPA for
the purpose of ensuring attainment of
the applicable NAAQS by the applicable
date. In addition, CAA section 189(c)(1)
requires quantitative milestones that
demonstrate RFP and must be achieved
every 3 years until the nonattainment
area is redesignated to attainment,
beginning 4.5 years after a Moderate
area’s designation to nonattainment of
the PM10 NAAQS.64 Therefore,
Moderate area plans should contain
quantitative milestones for 4.5 and 7.5
years after designation. These
quantitative milestones should be
constructed so that they can be tracked,
quantified and/or measured adequately,
and provide for an objective evaluation
of RFP toward attainment of the
NAAQS, particularly as part of
milestone reporting.65
2. Summary of the State’s Submission
The West Pinal County PM10 Plan
discusses how the Plan provides for RFP
in Section 7.2 and Appendix D and
provides visual representation in Figure
7–1 and Figure D 5–1.66 For the
purposes of calculating annual
increments of emission reductions for
RFP, ADEQ assumed a linear
‘‘glidepath’’ with equal annual
emissions reductions over the 2016–
2018 implementation timeframe. This
annual increment representing RFP is
7,475 tons per year.67 The
implementation of the Plan’s control
strategy is projected to produce almost
all the needed emissions reductions in
the first year, 2016, with slight and
incremental emission reductions to
follow in 2017 and 2018. Because ADEQ
projected that most of the emissions
reductions would come in the first year,
the projected emissions were below the
‘‘glidepath’’ and ADEQ concluded that
RFP was demonstrated.
3. The EPA’s Review of the State’s
Submission
Based in part on our review of the
2016–2018 ambient data and in part on
the flaws identified in the West Pinal
County PM10 Plan attainment
demonstration, we find that ADEQ did
not adequately provide for annual
increments of emissions reductions
needed to attain the PM10 NAAQS by
2018. Because the West Pinal County
64 Ibid.
65 81
FR 58063–64.
Pinal County PM10 Plan, 99 and Figure 7–
1, 101; Appendix D, 45.
67 West Pinal County PM
10 Plan, 100. Expected
emission reductions from 2015 to 2018, 22,426 tons
per year, are divided into 3 annual increments of
7,475 tons per year.
66 West
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PM10 plan failed to achieve attainment
by the attainment date, the RFP
demonstration based on the rate by
which these reductions were to occur is
also necessarily deficient. This was
borne out by the monitoring data; no
real rate of reduction of exceedances can
be demonstrated over the period of
implementation of the Plan’s control
measures, 2016–2018. Indeed, even with
the early implementation of additional
controls designated by the State as
contingency measures to provide
emissions reductions in the event of a
failure to show RFP or to attain, West
Pinal County still exceeded the PM10
standard by a large margin as evidenced
by the data in Table 5.
Regarding quantitative milestones,
given the EPA’s 2012 designation of
nonattainment for West Pinal County,
the State should have included
quantitative milestones for mid-2016
and mid-2019 within the West Pinal
County PM10 Plan. Aside from the two
glidepath depictions in Figure 7–1, the
Plan provides no further discussion of
quantitative milestones. What is
presented in Figure 7–1 does not meet
the criteria that the Plan’s quantitative
milestones should be trackable,
quantified, and provide for an objective
evaluation of RFP toward attainment of
the NAAQS, by mid-2016. The West
Pinal County PM10 Plan does not
address RFP or quantitative milestones
in mid-2019.
For these reasons, we have
determined that the West Pinal County
PM10 Plan fails to demonstrate RFP,
consistent with applicable CAA
requirements and EPA guidance.
Therefore, we propose to disapprove the
RFP demonstration and quantitative
milestones for the West Pinal County
area for the 24-hour PM10 NAAQS under
sections 172(c)(2) and 189(c)(1).
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F. Contingency Measures
1. Statutory and Regulatory
Requirements
Under the CAA, states must include
contingency measures consistent with
section 172(c)(9) in their nonattainment
plan SIP submissions. Contingency
measures are additional controls or
measures to be implemented in the
event the area fails to meet RFP or to
attain the NAAQS by the applicable
attainment date. The SIP should contain
trigger mechanisms for the contingency
measures, specify a schedule for
implementation, and indicate that the
measure will be implemented without
significant further action by the state or
the EPA.68
68 81
FR 58066 (August 24, 2016).
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Neither the CAA nor the EPA’s
implementing regulations establish a
specific level of emissions reductions
that implementation of contingency
measures must achieve, but the General
Preamble reiterates the EPA’s guidance
recommendation that contingency
measures should generally provide for
emissions reductions approximately
equivalent to one year’s worth of RFP in
the area.69 Where a failure to attain or
to meet RFP can be corrected in less
than one year, the EPA may accept a
proportionally lesser amount sufficient
to correct the identified failure.70
It has been the EPA’s longstanding
interpretation of CAA section 172(c)(9)
that states may meet the contingency
measure requirement by relying on
Federal measures (e.g., Federal mobile
source measures based on the
incremental turnover of the motor
vehicle fleet each year) and state or local
measures already scheduled for
implementation that provide emissions
reductions in excess of those needed to
meet any other nonattainment plan
requirements, such as RACM/RACT,
RFP, or expeditious attainment. The key
is that the Act requires that contingency
measures provide for additional
emissions reductions that are not relied
on for RFP or attainment and that are
not included in the RFP or attainment
demonstrations as meeting part of or all
the contingency measure requirements.
The purpose of contingency measures is
to provide continued emissions
reductions while a plan is being revised
to meet the missed milestone or
attainment date.
In Bahr v. EPA, the Ninth Circuit
Court of Appeals rejected the EPA’s
interpretation of CAA section 172(c)(9)
as allowing for early implementation of
contingency measures.71 The Ninth
Circuit concluded that contingency
measures must take effect at the time the
area fails to make RFP or attain by the
applicable attainment date, not before.72
Consequently, within the geographic
jurisdiction of the Ninth Circuit, states
cannot rely on early-implemented
measures to comply with the
contingency measure requirements
under CAA section 172(c)(9).73
69 57
FR 13498, 13543–13544.
at 13511.
71 Bahr v. EPA, 836 F.3d 1218, 1235–1237 (9th
Cir. 2016).
72 Id. at 1235–1237.
73 The Bahr v. EPA decision involved a challenge
to an EPA approval of contingency measures under
the general nonattainment area plan provisions for
contingency measures in CAA section 172(c)(9),
but, given the similarity between the statutory
language in section 172(c)(9) and the ozone-specific
contingency measure provision in section 182(c)(9),
we find that the decision affects how both sections
of the Act must be interpreted.
70 Id.
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2. Summary of the State’s Submission
ADEQ developed the West Pinal
County PM10 Plan prior to the Bahr v.
EPA decision, and the plan relies solely
upon surplus emissions reductions from
already implemented control measures
during the 2016–2018 period to
demonstrate compliance with the
contingency measure requirements of
CAA section 172(c)(9). The West Pinal
County PM10 Plan included the
following early implemented state and
local regulations to meet the
contingency measures requirement for
the PM10 standard: The portion of the
AgBMP Rules for Pinal County
applicable to dairy operations (R18–2–
611 and –611.03), and the Pinal County
Fugitive Dust Rule and Construction
Dust Rule.74 Contingency Measures are
also discussed in Appendix D.75
3. The EPA’s Review of the State’s
Submission
Arizona is within the geographic
jurisdiction of the Ninth Circuit Court of
Appeals; therefore, after the Bahr v. EPA
decision, the State cannot rely on
already-implemented control measures
to comply with the contingency
measure requirement of CAA section
172(c)(9). To comply with CAA section
172(c)(9), as interpreted in the Bahr v.
EPA decision, a state must develop,
adopt and submit contingency measures
to be triggered upon a failure to meet
RFP milestones or failure to attain the
NAAQS by the applicable attainment
date regardless of the extent to which
already-implemented measures would
achieve surplus emissions reductions
beyond those necessary to meet RFP
milestones and beyond those predicted
to achieve attainment of the NAAQS.
Arizona’s adopted and pre-implemented
contingency measures do not comply
with these requirements for failure to
make RFP and failure to meet
attainment contingency measures.
Section 172(c)(9) requires contingency
measures to address potential failures to
achieve RFP milestones or failure to
attain the NAAQS by the applicable
attainment date. For these reasons, we
propose to disapprove the contingency
measures element of the West Pinal
County PM10 Plan as failing to meet the
contingency measure requirements of
CAA sections 172(c)(9).
74 West Pinal County PM
10 Plan, Chapter 6;
Chapter 7, Table 7–4.
75 Appendix D, 45, Table D5–1.
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G. Motor Vehicle Emissions Budgets for
Transportation Conformity
1. Statutory and Regulatory
Requirements
Section 176(c) of the CAA requires
Federal actions in nonattainment and
maintenance areas to conform to the
goals of the state’s SIP to eliminate or
reduce the severity and number of
violations of the NAAQS and achieve
timely attainment of the standards.
Conformity to the goals of the SIP means
that such actions will not: (1) Cause or
contribute to violations of a NAAQS, (2)
worsen the severity of an existing
violation, or (3) delay timely attainment
of any NAAQS or any interim
milestone.
Actions involving Federal Highway
Administration (FHWA) or Federal
Transit Administration (FTA) funding
or approval are subject to the EPA’s
transportation conformity rule, codified
at 40 CFR part 93, subpart A. Under this
rule, metropolitan planning
organizations (MPOs) in nonattainment
and maintenance areas coordinate with
state and local air quality and
transportation agencies, the EPA, the
FHWA, and the FTA to demonstrate that
an area’s regional transportation plans
and transportation improvement
programs conform to the applicable SIP.
This demonstration is typically done by
showing that estimated emissions from
existing and planned highway and
transit systems are less than or equal to
the motor vehicle emissions budgets
(MVEBs or ‘‘budgets’’) contained in all
control strategy attainment plans
designed to attain the NAAQSs. Budgets
are generally established for specific
years and specific pollutants or
precursors. Attainment plans for PM10
nonattainment areas should identify
budgets for mobile source emissions of
PM10, i.e., vehicle and fugitive dust
emissions, in the area for each RFP
milestone year, as appropriate, and the
attainment year, if the plan
demonstrates attainment.76
For budgets to be approvable, they
must meet, at a minimum, the EPA’s
adequacy criteria at 40 CFR 93.118(e)(4).
To meet these requirements, the budgets
must be consistent with the attainment
and RFP requirements and reflect all the
motor vehicle control measures
contained in the attainment and RFP
demonstrations.77 Budgets may include
a safety margin representing the
76 40
CFR 93.102(b)(1).
CFR 93.118(e)(4)(iii), (iv) and (v). For more
information on the transportation conformity
requirements and applicable policies on MVEBs,
please visit our transportation conformity website
at: https://www.epa.gov/otaq/stateresources/
transconf/index.htm.
77 40
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difference between projected emissions
and the total amount of emissions
estimated to satisfy any requirements for
attainment or RFP.
The EPA’s process for determining
adequacy of a budget consists of three
basic steps: (1) Providing public
notification of a SIP submission; (2)
providing the public the opportunity to
comment on the budget during a public
comment period; and (3) making a
finding of adequacy or inadequacy.78
2. Summary of the State’s Submission
The West Pinal County PM10 Plan
includes a budget for the 2018
attainment year. As discussed in Section
III.E, we are proposing to disapprove the
RFP and quantitative milestones
elements of the Plan. No interim RFP
budget was submitted for 2016. The
State’s submitted 2018 conformity
budget for PM10 for the West Pinal
County Area is provided in Table 6.
TABLE 6—2018 MOTOR VEHICLE
EMISSIONS BUDGET FOR THE WEST
PINAL COUNTY PM10 NONATTAINMENT AREA
[Tons per year]
Source
Emissions
Direct On-Road Mobile Sources
(exhaust, tire and brake wear)
Unpaved Road Fugitive Dust .....
Paved Road Fugitive Dust .........
Road Construction/Maintenance
173.7
26,433.5
1,211.1
168.8
Total .....................................
27,987.1
Source: West Pinal County PM10 Plan,
Table 5–4.
The methodologies ADEQ used to
develop the motor vehicle emissions
budget are provided in Appendix B of
the West Pinal County PM10 Plan.79 As
discussed in section III.A. of this
proposal, ADEQ used MOVES2014 in
the development of this budget; this
emissions factor model was the latest
EPA approved version at the time the
West Pinal County PM10 Plan was
developed. Paved road vehicle miles
traveled (VMT) estimates for estimating
direct and fugitive PM10 emissions were
provided by MAG using an
interpolation methodology where 2018
VMT was estimated from 2015 and 2025
regional transportation modeling runs.80
ADEQ used the most recently approved
EPA provided AP–42 emissions factor
equations to develop paved and
unpaved road fugitive dust emissions
78 40
CFR 93.118(f)(2).
B, 120–137, and 166–180.
80 Appendix B, 120.
79 Appendix
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estimates.81 In addition to the line item
source categories in the 2018 budget
presented in Table 6, ADEQ specified
that the budget includes an 81 ton per
year safety margin.82
The EPA has neither found this 2018
budget to be adequate, nor have we
acted on it in the past.
3. The EPA’s Review of the State’s
Submission
As part of our review of the
approvability of the motor vehicle
emissions budget in the West Pinal
County PM10 Plan, we have evaluated
the budget using the adequacy criteria
specified in the transportation
conformity rule.83 Reviewing the budget
against the criteria in the transportation
conformity rule informs the EPA’s
decision to propose our action on the
budget. We have determined that the
2018 budget submitted by Arizona for
the West Pinal County area has not met
several of these criteria.
First and foremost, § 93.118(e)(4)(iv)
requires that a budget, when considered
together with all other emissions
sources, be consistent with applicable
requirements for RFP, attainment, or
maintenance (whichever is relevant to a
given implementation plan submission).
In this case, the West Pinal County area
budget is not consistent with the
requirements for attainment and RFP, as
discussed in Sections III.D and E of this
proposal and our proposed disapproval
of these two Plan elements. Secondly,
the West Pinal County budget is
presented in a tons per year format for
an attainment plan intended to meet the
24-hour PM10 NAAQS. The budget must
be consistent with the 24-hour
timeframe of the attainment
demonstration and PM10 standard, and
therefore should be presented in a tons
per day format. Finally,
§ 93.118(e)(4)(iii) requires that the
budget be clearly identified and
precisely quantified. Although ADEQ
describes an ‘‘allowance or safety
margin’’ in the West Pinal County PM10
Plan, the submitted budget does not
clearly and explicitly identify this safety
margin in its presentations of the
budget.84 Also, a safety margin, as
81 ADEQ used the appropriate AP–42 guidance in
sections 13.2.1 and 13.2.2 to calculate fugitive dust
from paved and unpaved roads. The AP–42
emission factor equation inputs for estimating
unpaved road fugitive dust emissions can be found
in Appendix B, Table 5–11. The most recent EPA
revision and approval of these AP–42 emission
factor equations occurred in 2011 and are reflected
in the Plan’s estimates; 76 FR 6328 (February 4,
2011).
82 West Pinal County PM
10 Plan, 62.
83 40 CFR 93.118(e)(4) and (5).
84 West Pinal County PM
10 Plan, Table 5–4;
Appendix D, Table D4–4.
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defined in the Transportation
Conformity rule, § 93.101, must be
clearly presented and demonstrated to
be outside and above the emissions
level demonstrating attainment, but
below the threshold of the applicable
NAAQS.
We have reviewed the motor vehicle
emissions budget in the West Pinal
County PM10 Plan and find that it does
not meet applicable statutory and
regulatory requirements including the
adequacy criteria in 40 CFR
93.1118(e)(4) and (5). The primary
deficiency is that the submitted 2018
budget is not consistent with, or derived
from, a demonstration of attainment and
RFP meeting the requirements of the
Act. As discussed earlier in sections
III.D and III.E, we are proposing herein
to disapprove the Plan’s attainment and
RFP demonstrations. Therefore, we are
proposing to disapprove the 2018
budget in the West Pinal County PM10
Plan. In addition, because we are
disapproving the attainment and RFP
demonstrations, the 2018 budget is not
eligible for a protective finding.85
If our proposed disapproval of the
2018 budget is finalized, upon the
effective date of our final rule, the area
would be subject to a conformity freeze
under § 93.120 of the Transportation
Conformity rule. No transportation
project outside of the first four years of
the currently conforming transportation
plan and transportation improvement
plan (TIP) or that meets the
requirements of § 93.104(f) during the
resulting conformity freeze may be
found to conform until Arizona submits
a new PM10 control strategy/attainment
plan, the EPA finds the submitted
budget adequate per § 93.118 or
approves the new control strategy/
attainment plan and conformity to the
new control/strategy implementation
plan is determined.86 Furthermore, if, as
a result of our final disapproval action,
the EPA imposes highway sanctions
under section 179(b)(1) of the Act two
years from the effective date of our final
rule, then the conformity status of the
transportation plan and TIP will lapse
on that date and no new transportation
plan, TIP, or project may be found to
conform until Arizona submits a new
PM10 attainment plan, and conformity to
this attainment plan is determined.87
IV. Proposed Action
For the reasons discussed in this
notice, under CAA section 110(k)(3), the
EPA is proposing to approve and
disapprove the following portions of the
85 40
CFR 93.120(a)(3).
CFR 93.120(a)(2).
87 40 CFR 93.120(a)(1).
86 40
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West Pinal County PM10 Plan, submitted
by the State on December 21, 2015. Our
proposed approval and disapproval
actions are as follows:
• We propose to approve the 2008
base year emissions inventory element
for direct PM10 in the West Pinal County
PM10 Plan as meeting the requirements
of CAA sections 172(c)(3) for the 1987
p.m.10 NAAQS;
• We propose to disapprove the
precursor demonstration in the West
Pinal County PM10 Plan because the
demonstration is inadequate to show
that emissions reductions from all PM10
precursors do not contribute
significantly to PM10 levels exceeding
the NAAQS, as required by CAA
Section 189(e) for the 1987 p.m.10
NAAQS;
• We propose to disapprove the
RACM/RACT demonstration element in
the West Pinal County PM10 Plan
because it does not meet the
requirements of CAA section 172(c)(1)
and section 189(a)(1)(C) for the 1987
p.m.10 NAAQS; furthermore, the
deficiencies in the State’s precursor
analysis mean that the State failed to
establish in its RACM/RACT analysis
that it was unnecessary to regulate PM10
precursor emissions;
• We propose to disapprove the
modeled attainment demonstration
element for the 1987 p.m.10 NAAQS in
the West Pinal County PM10 Plan
because it does not meet the
requirements of CAA section
189(a)(1)(B) and section 188(c)(1) to
demonstrate attainment of the 1987
p.m.10 NAAQS;
• We propose to disapprove the RFP
demonstration element in the West
Pinal County PM10 Plan because it does
not meet the requirements of CAA
sections 172(c)(2) for the 1987 p.m.10
NAAQS;
• We propose to disapprove the
quantitative milestones element in the
West Pinal County PM10 Plan because it
does not meet the requirements of CAA
section 189(c)(1) for the 1987 p.m.10
NAAQS;
• We propose to disapprove the
contingency measures element of the
West Pinal County PM10 Plan because it
does not meet the requirements of CAA
section 172(c)(9) for the 1987 p.m.10
NAAQS; and,
• We propose to disapprove the
motor vehicle emissions budget in West
Pinal County PM10 Plan for the
attainment year of 2018 (see Table 6)
because it is not consistent with or
derived from, approvable RFP or and
attainment demonstrations for the 1987
PM10 NAAQS meeting the requirements
of the Act.
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1361
The EPA is soliciting public
comments on the issues discussed in
this proposed rule. We will accept
comments from the public on this
proposal for the next 30 days and will
consider those comments before taking
final action.
V. Statutory and Executive Order
Reviews
Additional information about these
statutes and Executive orders can be
found at https://www.epa.gov/lawsregulations/laws-and-executive-orders.
A. Executive Order 12866: Regulatory
Planning and Review and Executive
Order 13563: Improving Regulation and
Regulatory Review
This action is not a significant
regulatory action and was therefore not
submitted to the Office of Management
and Budget (OMB) for review.
B. Executive Order 13771: Reducing
Regulations and Controlling Regulatory
Costs
This action is not an Executive Order
13771 regulatory action because SIP
approvals, including partial approvals,
are exempted under Executive Order
12866.
C. Paperwork Reduction Act (PRA)
This action does not impose an
information collection burden under the
PRA because this action does not
impose additional requirements beyond
those imposed by state law.
D. Regulatory Flexibility Act (RFA)
I certify that this action will not have
a significant economic impact on a
substantial number of small entities
under the RFA. This action will not
impose any requirements on small
entities beyond those imposed by state
law.
E. Unfunded Mandates Reform Act
(UMRA)
This action does not contain any
unfunded mandate as described in
UMRA, 2 U.S.C. 1531–1538, and does
not significantly or uniquely affect small
governments. This action does not
impose additional requirements beyond
those imposed by state law.
Accordingly, no additional costs to
state, local, or tribal governments, or to
the private sector, will result from this
action.
F. Executive Order 13132: Federalism
This action does not have federalism
implications. It will not have substantial
direct effects on the states, on the
relationship between the National
Government and the states, or on the
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distribution of power and
responsibilities among the various
levels of government.
Particulate matter, Reporting and
recordkeeping requirements.
G. Executive Order 13175: Coordination
With Indian Tribal Governments
Dated: December 23, 2020.
John Busterud,
Regional Administrator, Region IX.
Authority: 42 U.S.C. 7401 et seq.
This action does not have tribal
implications, as specified in Executive
Order 13175, because the SIP is not
approved to apply on any Indian
reservation land or in any other area
where the EPA or an Indian tribe has
demonstrated that a tribe has
jurisdiction, and will not impose
substantial direct costs on tribal
governments or preempt tribal law.
Thus, Executive Order 13175 does not
apply to this action.
H. Executive Order 13045: Protection of
Children From Environmental Health
Risks and Safety Risks
The EPA interprets Executive Order
13045 as applying only to those
regulatory actions that concern
environmental health or safety risks that
the EPA has reason to believe may
disproportionately affect children, per
the definition of ‘‘covered regulatory
action’’ in section 2–202 of the
Executive order. This action is not
subject to Executive Order 13045
because it does not impose additional
requirements beyond those imposed by
state law.
I. Executive Order 13211: Actions That
Significantly Affect Energy Supply,
Distribution, or Use
This action is not subject to Executive
Order 13211, because it is not a
significant regulatory action under
Executive Order 12866.
J. National Technology Transfer and
Advancement Act (NTTAA)
Section 12(d) of the NTTAA directs
the EPA to use voluntary consensus
standards in its regulatory activities
unless to do so would be inconsistent
with applicable law or otherwise
impractical. The EPA believes that this
action is not subject to the requirements
of section 12(d) of the NTTAA because
application of those requirements would
be inconsistent with the CAA.
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K. Executive Order 12898: Federal
Actions To Address Environmental
Justice in Minority Populations and
Low-Income Populations
The EPA lacks the discretionary
authority to address environmental
justice in this rulemaking.
List of Subjects in 40 CFR Part 52
Environmental protection, Air
pollution control, Incorporation by
reference, Intergovernmental relations,
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[FR Doc. 2020–29092 Filed 1–7–21; 8:45 am]
BILLING CODE 6560–50–P
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Part 63
[EPA–HQ–OAR–2020–0560; FRL–10018–95–
OAR]
RIN 2060–AU59
National Emission Standards for
Hazardous Air Pollutants: Mercury Cell
Chlor-Alkali Plants Residual Risk and
Technology Review
Environmental Protection
Agency (EPA).
ACTION: Proposed rule.
AGENCY:
The U.S. Environmental
Protection Agency (EPA) is proposing
the results of the residual risk and
technology review (RTR) of the National
Emission Standards for Hazardous Air
Pollutants (NESHAP) for mercury
emissions from Mercury Cell ChlorAlkali Plants, as required by the Clean
Air Act (CAA). The EPA is proposing to
find risks due to emissions of hazardous
air pollutants (HAP) to be acceptable
from the Mercury Cell Chlor-Alkali
Plants source category, and to determine
that the current NESHAP provides an
ample margin of safety to protect public
health and that no more stringent
standards are necessary to prevent,
taking into consideration costs, energy,
safety, and other relevant factors, an
adverse environmental effect. The EPA
is proposing to amend the requirements
for cell room fugitive mercury emissions
to require work practice standards for
the cell rooms and to require
instrumental monitoring of cell room
fugitive mercury emissions under the
technology review. Furthermore, under
our technology review and maximum
achievable control technology (MACT)
analysis, we are proposing to not require
conversion to non-mercury production
technology and invite comments and
data and information regarding this
proposed determination. In addition,
the EPA is proposing standards for
fugitive chlorine emissions from
mercury cell chlor-alkali plants, which
are not currently regulated under the
NESHAP. The EPA is proposing to
address applicability for thermal
mercury recovery units when chlorine
SUMMARY:
PO 00000
Frm 00060
Fmt 4702
Sfmt 4702
and caustic are no longer produced in
mercury cells. The EPA is also
proposing revisions related to emissions
during periods of startup, shutdown,
and malfunction (SSM); provisions for
electronic submission of performance
test results, performance evaluation
reports, and Notification of Compliance
Status (NOCS) reports; and correction of
various compliance errors in the current
rule.
DATES:
Comments. Comments must be
received on or before February 22, 2021.
Under the Paperwork Reduction Act
(PRA), comments on the information
collection provisions are best assured of
consideration if the Office of
Management and Budget (OMB)
receives a copy of your comments on or
before February 8, 2021.
Public hearing: If anyone contacts us
requesting a public hearing on or before
January 13, 2021, we will hold a virtual
public hearing. See SUPPLEMENTARY
INFORMATION for information on
requesting and registering for a public
hearing.
You may send comments,
identified by Docket ID No. EPA–HQ–
OAR–2020–0560, by any of the
following methods:
• Federal eRulemaking Portal:
https://www.regulations.gov/ (our
preferred method). Follow the online
instructions for submitting comments.
• Email: a-and-r-docket@epa.gov.
Include Docket ID No. EPA–HQ–OAR–
2020–0560 in the subject line of the
message.
• Fax: (202) 566–9744. Attention
Docket ID No. EPA–HQ–OAR–2020–
0560.
• Mail: U.S. Environmental
Protection Agency, EPA Docket Center,
Docket ID No. EPA–HQ–OAR–2020–
0560, Mail Code 28221T, 1200
Pennsylvania Avenue NW, Washington,
DC 20460.
• Hand Delivery or Courier (by
scheduled appointment only): EPA
Docket Center, WJC West Building,
Room 3334, 1301 Constitution Avenue
NW, Washington, DC 20004. The Docket
Center’s hours of operation are 8:30
a.m.–4:30 p.m., Monday–Friday (except
Federal holidays).
Instructions: All submissions received
must include the Docket ID No. for this
rulemaking. Comments received may be
posted without change to https://
www.regulations.gov/, including any
personal information provided. For
detailed instructions on sending
comments and additional information
on the rulemaking process, see the
SUPPLEMENTARY INFORMATION section of
this document. Out of an abundance of
ADDRESSES:
E:\FR\FM\08JAP1.SGM
08JAP1
]]>Agencies
[Federal Register Volume 86, Number 5 (Friday, January 8, 2021)]
[Proposed Rules]
[Pages 1347-1362]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-29092]
=======================================================================
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R09-OAR-2020-0618; FRL-10018-46-Region 9]
Partial Approval and Partial Disapproval of Air Quality
Implementation Plans; Arizona; West Pinal County; 1987 PM10
Nonattainment Area Requirements
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
approve in part and to disapprove in part the state implementation plan
(SIP) revision submitted by the State of Arizona to meet Clean Air Act
(CAA or ``Act'') requirements for the 1987 PM10 national
ambient air quality standards (NAAQS or ``standard'') in the West Pinal
County PM10 nonattainment area. The State of Arizona's
``2015 West Pinal Moderate PM10 Nonattainment Area SIP''
(``West Pinal County PM10 Plan'') addresses the CAA
nonattainment area requirements for the 1987 PM10 NAAQS,
including requirements for an emissions inventory, an attainment
demonstration, reasonable further progress, reasonably available
control measures, contingency measures, and motor vehicle emissions
budgets. The EPA is proposing to approve the base year 2008 emissions
inventory for direct PM10 and to disapprove the remaining
elements of the West Pinal County PM10 Plan.
DATES: Written comments must arrive on or before February 8, 2021.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2020-0618 at https://www.regulations.gov. For comments submitted at
Regulations.gov, follow the online instructions for submitting
comments. Once submitted, comments cannot be edited or removed from
Regulations.gov. The EPA may publish any comment received to its public
[[Page 1348]]
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, or if you need assistance in a language
other than English or if you are a person with disabilities who needs a
reasonable accommodation at no cost to you, please contact the person
identified in the FOR FURTHER INFORMATION CONTACT section. For the full
EPA public comment policy, information about CBI or multimedia
submissions, and general guidance on making effective comments, please
visit https://www.epa.gov/dockets/commenting-epa-dockets. If you need
assistance in a language other than English or if you are a person with
disabilities who needs a reasonable accommodation at no cost to you,
please contact the person identified in the FOR FURTHER INFORMATION
CONTACT section.
FOR FURTHER INFORMATION CONTACT: Jerry Wamsley, Air Planning Office
(ARD-2), EPA Region IX, 75 Hawthorne Street, San Francisco, CA 94105,
(415) 947-4111, or by email at [email protected].
SUPPLEMENTARY INFORMATION: Throughout this document, ``we,'' ``us,''
and ``our'' refer to the EPA.
Table of Contents
I. Regulatory Context
A. PM10 Standard, Area Designations, and SIPs
B. CAA and Regulatory Requirements for Moderate PM10
Nonattainment Area SIPs
II. Submissions From the State of Arizona To Address 1987
PM10 Standard Requirements in the West Pinal County
Nonattainment Area
A. Summary of State Submissions
B. CAA Procedural Requirements for Adoption and Submission of
SIP Revisions
III. Evaluation of the West Pinal County PM10 Plan
A. Emissions Inventories
B. PM10 Precursors
C. Reasonably Available Control Measures Demonstration
D. Attainment Demonstration
E. Reasonable Further Progress Demonstration
F. Contingency Measures
G. Motor Vehicle Emissions Budgets for Transportation Conformity
IV. Proposed Action
V. Statutory and Executive Order Reviews
I. Regulatory Context
A. PM10 Standard, Area Designations, and SIPs
The EPA sets the National Ambient Air Quality Standard (NAAQS) for
certain ambient air pollutants at levels required to protect human
health and the environment. Particulate matter with an aerodynamic
diameter less than or equal to a nominal ten micrometers, or
PM10, is one of these ambient air pollutants for which the
EPA has established health-based standards. On July 1, 1987, the EPA
promulgated two primary standards for PM10: A 24-hour
standard of 150 micrograms per cubic meter ([micro]g/m\3\); and an
annual PM10 standard of 50 [micro]g/m\3\. The EPA also
promulgated secondary PM10 standards that were identical to
the primary standards.\1\ Because they are identical, we refer to the
primary and secondary standards using the singular term, NAAQS.
Effective December 18, 2006, EPA revoked the annual PM10
NAAQS but retained the 24-hour PM10 NAAQS.\2\
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\1\ 52 FR 24634 (July 1, 1987).
\2\ 71 FR 61144 (October 17, 2006).
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An area attains the 24-hour PM10 NAAQS when the expected
number of days per calendar year with a 24-hour concentration in excess
of 150 micrograms per cubic meter ([micro]g/m\3\) (referred to herein
as an ``exceedance''), is equal to or less than one as determined in
accordance with 40 CFR part 50, appendix K.\3\ Conversely, a violation
of the PM10 NAAQS occurs when the number of expected annual
exceedances of the 24-hour NAAQS is greater than one.
---------------------------------------------------------------------------
\3\ See 40 CFR 50.6 and 40 CFR part 50, appendix K.
---------------------------------------------------------------------------
Most of Pinal County, Arizona, including what is now the West Pinal
County PM10 nonattainment area, was included in the ``rest
of state'' area, which was designated ``unclassifiable'' for the 24-
hour PM10 NAAQS by operation of law upon enactment of the
CAA, consistent with section 107(d)(4)(B)(iii). Until recently, this
area in Arizona remained designated ``unclassifiable'' for the 1987 24-
hour PM10 NAAQS. The CAA, under section 107(d)(3),
authorizes the EPA to revise the designation of, or ``redesignate,''
areas (or portions thereof) based on air quality data, planning and
control considerations, or any other air-quality-related considerations
that the EPA deems appropriate.
On October 14, 2009, under CAA section 107(d)(3)(A), the EPA
notified the Governor of Arizona and four tribal leaders (whose areas
of Indian country are located entirely, or in part, within Pinal
County) that the designation for Pinal County, and any nearby areas
that may be contributing to the monitored violations in Pinal County,
should be revised.\4\ Our decision to initiate the redesignation
process was due to ambient data for 2006-2008 from PM10
monitoring sites within the County showing widespread, frequent, and in
some instances, severe, violations of the PM10 standard.
---------------------------------------------------------------------------
\4\ Letter from Laura Yoshii, Acting Regional Administrator to
Governor Jan Brewer dated October 14, 2009. The EPA notified the
tribal leaders of the Ak-Chin Indian Community, Gila River Indian
Community, San Carlos Apache Tribe by letters dated December 30,
2009, and Tohono O'odham Nation by letter dated September 21, 2010.
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Effective July 2, 2012, the EPA designated a portion of state lands
in Pinal County, Arizona (``West Pinal County'') as nonattainment for
the 1987 PM10 NAAQS based on monitoring data from 2006-
2008.\5\ West Pinal County is located in central Arizona, southeast of
the Phoenix metropolitan area and northwest of the city of Tucson.
Pinal County covers 5,365 square miles and has two distinct western and
eastern regions with different characteristics relevant to pollution
formation. The West Pinal County PM10 nonattainment area is
located within the western region, characterized by low desert valleys
and an arid climate. The eastern region is mountainous, with elevations
up to 6,441 feet.
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\5\ 77 FR 32024 (May 31, 2012). The precise boundaries for the
West Pinal County nonattainment area are described in 40 CFR 81.303.
---------------------------------------------------------------------------
As a result of the nonattainment designation, EPA classified West
Pinal County as a ``Moderate'' PM10 nonattainment area.
Consequently, by January 2, 2014, Arizona was required to submit a
nonattainment plan SIP revision for the 24-hour PM10 NAAQS
meeting relevant CAA requirements. The State submitted a SIP revision
intended to meet these requirements on December 21, 2015, and this
``2015 West Pinal Moderate PM10 Nonattainment Area SIP'' is
the subject of this proposed action. For a PM10
nonattainment area classified as Moderate, section 188(c) of the CAA
provides that the Moderate area attainment date is ``as expeditiously
as practicable, but no later than the end of the sixth calendar year
after the area's designation as nonattainment.'' Consequently, the
applicable attainment date for the West Pinal County area, designated
nonattainment in 2012, was as expeditiously as practicable, but no
later than December 31, 2018.
CAA section 188(b)(2) requires the EPA to determine whether a state
has
[[Page 1349]]
attained the 24-hour PM10 NAAQS in a Moderate
PM10 nonattainment area by the applicable attainment date
and requires the EPA to make such a determination within six months
after that date. If the EPA determines that a Moderate area has not
attained the NAAQS by the relevant attainment date, then the area is
reclassified as a Serious area by operation of law. On June 24, 2020,
the EPA determined that the West Pinal County nonattainment area had
not attained the 1987 24-hour PM10 NAAQS by December 31,
2018, the outermost permissible statutory attainment date for the
area.\6\ This determination was based on our calculation of the
PM10 design value for the West Pinal County nonattainment
area over the 2016-2018 period, using complete, quality-assured, and
certified PM10 monitoring data.
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\6\ 85 FR 37756 (June 24, 2020).
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The basis for the EPA's June 24, 2020 finding of failure to attain
the PM10 NAAQS and the margin by which the area failed to
attain indicate that the Moderate plan's modeled attainment
demonstration, which incorrectly predicted attainment of the
PM10 NAAQS by December 31, 2018, is not approvable. Because
the modeled attainment demonstration is not approvable, as described in
section III.D, other elements of the West Pinal County PM10
Plan that are dependent upon the modeled attainment demonstration are
likewise not approvable, e.g., the emission controls imposed by the
State to meet reasonably available control measure/reasonably available
control technology (RACM/RACT) requirements based on the predicted
sufficiency of those controls to result in attainment by the intended
attainment date. If finalized as we propose, our disapproval of most
elements of the Moderate plan will start sanctions and Federal
implementation plan (FIP) clocks, which can be turned off by the EPA's
approval of new plan elements for the PM10 NAAQS that
correct the deficiencies within the Moderate plan. With the EPA's
reclassification of the West Pinal County area to Serious, Arizona now
has an obligation to submit, by January 24, 2022, a nonattainment plan
SIP revision that complies with the statutory and regulatory
requirements for Serious PM10 nonattainment plans and that
demonstrates attainment of the PM10 NAAQS as expeditiously
as practicable, but no later than December 31, 2022. Although
reclassification of an area from Moderate to Serious does not eliminate
a state's obligation to meet Moderate area nonattainment plan
requirements, the EPA anticipates that Arizona's submission of an
approvable Serious area nonattainment plan would also satisfy the
State's Moderate area nonattainment plan obligations. For example, an
approvable Serious area nonattainment plan would satisfy the Act's
requirements for imposing best available control measures, including
best available control technology (BACM/BACT), which would presumably
satisfy the less stringent requirements for RACM/RACT.
B. CAA and Regulatory Requirements for Moderate PM10
Nonattainment Area SIPs
Along with the new designations, classifications, and attainment
dates, the Clean Air Act Amendments of 1990 established new
nonattainment area planning requirements. The air quality planning
requirements for Moderate PM10 nonattainment areas are set
out in subparts 1 and 4 of the CAA, including sections 110, 172, and
189 of the statute. We discuss these sections of the Act in more detail
later during our review of each plan element. Also, the EPA has issued
guidance, in a document we refer to as the General Preamble, describing
how we will review state nonattainment plan SIP submissions under Title
I of the CAA, including such SIP submissions for Moderate
PM10 nonattainment areas.\7\ In general, states must include
the following elements in nonattainment plans for Moderate areas for
purposes of the 1987 24-hour PM10 NAAQS: A comprehensive,
accurate, and current emissions inventory of emissions sources in the
nonattainment area; provisions to implement RACM/RACT for the
appropriate sources and pollutants in the nonattainment area;
provisions demonstrating reasonable further progress (RFP), including
quantitative milestones towards attainment of the PM10 NAAQS
as expeditiously as practicable, along with quantitative milestones for
evaluation of RFP at set times; contingency measures that will provide
for additional emissions reductions automatically in the event that the
state fails to meet RFP or to attain the NAAQS by the applicable
attainment date in the area; and, a motor vehicle emissions budget for
the purpose of determining the conformity of transportation programs
and plans developed by state transportation agencies.
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\7\ 57 FR 13498 (April 16, 1992) and 57 FR 18070 (April 28,
1992).
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II. Submissions From the State of Arizona To Address the 1987 PM10
Standard Requirements in the West Pinal County Nonattainment Area
A. Summary of State Submissions
As a result of the May 31, 2012 nonattainment designation, West
Pinal County was classified as a Moderate PM10 nonattainment
area. Within 18 months from the July 2, 2012 effective date of the
designation, or January 2, 2014, the State was required to submit a
nonattainment plan meeting Moderate area plan requirements, including
emission control measures for West Pinal County designed to attain the
1987 24-hour PM10 NAAQS as expeditiously as practicable, but
no later than December 31, 2018.
On December 21, 2015, Arizona submitted the West Pinal County
PM10 Plan, intended to address the Moderate area
nonattainment requirements, to the EPA as a revision to the Arizona
SIP.\8\ The West Pinal County PM10 Plan is organized into
seven chapters and nine appendices. The nine appendices provide support
for the plan and are divided into the following categories: Technical
support and documentation (appendices A-D, F), SIP adoption authority
and public notice and hearing documentation (appendix E) and control
measure submittals (appendices G-I).
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\8\ Letter dated December 21, 2015, from Eric C. Massey,
Director, Air Quality Division, Arizona Department of Environmental
Quality, to Jared Blumenfeld, Regional Administrator, EPA Region IX.
---------------------------------------------------------------------------
Appendices G, H, and I contain control measures submitted with the
West Pinal County PM10 Plan in the form of rules, statutes,
and other supporting documents. We are not proposing to act on the
submitted control measures in this proposed action on the West Pinal
County PM10 Plan. Previously, the EPA approved into the
Arizona SIP the submitted control measures that regulate fugitive dust,
construction dust, and crop operations.\9\ In a separate Federal
Register notice, we intend to take action on the remainder of the
State's submitted rules, namely, an update to its agricultural best
management practices (AgBMP) statute, and the AgBMP rules for animal
operations in Pinal County.
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\9\ 82 FR 20267 (May 1, 2017).
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B. CAA Procedural Requirements for Adoption and Submission of SIP
Revisions
CAA sections 110(a) and 110(l) require a state to provide
reasonable public notice and opportunity for public hearing prior to
the adoption and submission of a SIP revision to the EPA
[[Page 1350]]
for evaluation under section 110(k) and other applicable substantive
requirements. To meet this procedural requirement, a state must include
evidence that it provided adequate public notice and an opportunity for
a public hearing, consistent with the EPA's implementing regulations in
40 CFR 51.102.
The Arizona Department of Environmental Quality (ADEQ) provided
public notice and opportunity for public comment on the West Pinal
County PM10 Plan. On October 19, 2015, ADEQ released the
West Pinal County PM10 Plan for public review and published
a notice of public meeting to be held on November 19, 2015, to consider
adoption of the West Pinal County PM10 Plan.\10\ On November
19, 2015, ADEQ held the public hearing and subsequently adopted the
West Pinal County PM10 Plan as a revision to the Arizona
SIP.\11\ Under authority provided by Arizona state law, on December 21,
2015, Eric Massey, Director of the Air Quality Division, ADEQ,
submitted the West Pinal County PM10 Plan to the EPA.\12\ On
June 21, 2016, the West Pinal County PM10 Plan became
complete by operation of law.\13\
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\10\ ``Arizona Department of Environmental Quality and Public
Comment Period and Hearing on the Proposed Arizona State
Implementation Plan Revision, Attainment Plan for the West Pinal
County PM10 Planning Area (1987 NAAQS)'' published in the
Arizona Republic October 19 and 20, 2015; Exhibit E-III, Appendix E,
West Pinal County PM10 Plan.
\11\ ``Public Hearing Presiding Officer Certification'' signed
by Naveen Savarirvayan, Presiding Officer, November 19, 2015 and
notarized; Exhibit E-VI, Appendix E, West Pinal County
PM10 Plan. The hearing transcript and the public comments
and State responses are found at Exhibit E-VIII and Exhibit E-VII,
respectively, within Appendix E, West Pinal County PM10
Plan.
\12\ Letter dated December 21, 2015 from Eric C. Massey,
Director, Air Quality Division, ADEQ to Jared Blumenfeld, Regional
Administrator, EPA Region IX.
\13\ 42 U.S.C. 7410(k)(1)(B).
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Based on information provided in the SIP submissions summarized
above, the EPA has determined that the public hearing was properly
noticed. Therefore, we find that the submittal of the West Pinal County
PM10 Plan meets the procedural requirements for public
notice and hearing in CAA sections 110(a) and 110(l) and 40 CFR 51.102.
III. Evaluation of the West Pinal County PM10 Plan
A. Emissions Inventories
1. Statutory and Regulatory Requirements
CAA section 172(c)(3) requires a state to submit for each
PM10 nonattainment area a ``base year inventory'' that is a
comprehensive, accurate, current inventory of actual emissions from all
sources of the relevant pollutant or pollutants in the area. Also, the
state should submit a second projected ``attainment year inventory''
for the year in which the state projects that the area will attain the
PM10 standards. The state should include documentation
explaining how it calculated the emissions data. When estimating mobile
source emissions, states should use the latest emissions models and
planning assumptions available at the time the SIP is developed.\14\
---------------------------------------------------------------------------
\14\ See 81 FR 58032 (August 24, 2016).
---------------------------------------------------------------------------
The state must meet several general requirements for base year
emissions inventories, consistent with CAA section 172(c)(3). First,
the emissions inventory year must be one of the 3 years used for the
EPA PM10 nonattainment designation for the area, or an
alternative year agreed upon by the EPA and the state as more
reflective of the causes and sources of violations of the
PM10 standard that meet the criteria in CAA section
172(c)(3). Second, the state must reflect actual emissions from all
sources of PM10 in the inventory. Third, the state should
report the emissions inventory in the form of the PM10
standard it is intended to address, e.g., in tons or pounds per day to
be consistent with the averaging period of the 24-hour PM10
NAAQS.\15\
---------------------------------------------------------------------------
\15\ See 81 FR 58027-58032.
---------------------------------------------------------------------------
A state must meet similar CAA section 172(c)(3) requirements in the
projected attainment year inventory for the most expeditious year in
which the state can show attainment of the PM10 standard in
the modeled attainment demonstration portion of the nonattainment plan.
At a minimum, the state must choose an attainment year consistent with
the outermost applicable deadline required by CAA section 188(c). As
with the baseline year inventory, the state must reflect emissions from
all sources of PM10 in this inventory and report them in the
form of the PM10 standard. In addition, the attainment year
inventory must be consistent with the source categories and level of
detail reported by the state in the base year inventory.
Future attainment year and related baseline emissions inventories
must reflect the most recent population, employment, travel and
congestion estimates for the area. In this context, ``baseline''
emissions inventories refer to emissions estimates for a given year and
area that reflect rules and regulations and other measures that are
already adopted in a state's EPA approved SIP and assumed within the
attainment demonstration. Future baseline emissions inventories are
necessary to show the projected effectiveness of SIP control measures
designed to result in attainment by the applicable attainment year.
Both the base year and future year, baseline and attainment inventories
are necessary inputs to any modeling or other analyses required to
demonstrate attainment of the PM10 standard, as required by
section 189(a)(1)(B).
2. Summary of State's Submission
The West Pinal County PM10 Plan includes a base year
(2008) inventory, and future year (2018) baseline and attainment
emissions inventories for direct PM10 in the West Pinal
County area. The State provided documentation for the emissions
inventories in Chapter 5 (``Annual Emissions Inventory'') of the West
Pinal County PM10 Plan and its two-part Appendix B (``Pinal
County PM10 Nonattainment Area Emissions Inventories for
2008 and 2018 Base Years and Design Days'', and its supporting
``Exhibits'').\16\ The emissions inventories are provided in two parts,
one representing windblown PM10 emissions on high-wind days
(including both entrained dust and windblown dust from human
activities), and the second representing PM10 emissions on
low-wind days (including dust due to human activity that stagnates near
its point of origin). The State presents the annual emissions
inventories on a tons per year basis that it later converts to a tons
or pounds per day basis for use within the attainment demonstration
modeling for the 24-hour NAAQS at issue.
---------------------------------------------------------------------------
\16\ As needed, we will refer to the primary document as
``Appendix B'' and the secondary document as ``Appendix B-
Exhibits.''
---------------------------------------------------------------------------
The 2018 attainment year emissions inventories reflect State of
Arizona and Pinal County rules adopted concurrently with the West Pinal
County PM10 Plan in late 2015.\17\ The Plan's emissions
reductions are based on continuing implementation of existing Federal
controls along with new state and local control measures submitted with
the Plan. The 2008 base year and projected 2018 baseline and attainment
year inventories use the most recent EPA-approved mobile source
emissions model at the time the plan was developed, MOVES2014, for
estimating on-road motor vehicle emissions.\18\ Future emissions
forecasts in the West Pinal County PM10 Plan, particularly
on-road mobile source emissions, are based primarily on
[[Page 1351]]
demographic and economic growth projections provided by Arizona
Department of Administration and the Maricopa Association of
Governments (MAG).\19\
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\17\ Please refer to Appendices G, H, and I, West Pinal County
PM10 Plan for rule adoption information.
\18\ Appendix B, 62.
\19\ West Pinal County PM10 Plan, 27-28, Table 3-3;
Appendix B, 120, 132, and 132 at footnote 97.
---------------------------------------------------------------------------
In general, the term ``point sources'' typically refers to
permitted facilities that have one or more identified and fixed pieces
of equipment and emissions points. ``Area sources'' typically consist
of widespread and numerous smaller emissions sources, such as small
permitted facilities and households. The ``mobile sources'' category
refers to vehicles and is typically divided into two major
subcategories, ``on-road'' and ``non-road'' mobile sources. On-road
mobile sources include light-duty automobiles, light-, medium-, and
heavy-duty trucks, and motorcycles. In addition to tailpipe, brake, and
tire wear, on-road mobile emissions estimates for PM10 also
include re-entrained dust from vehicles driven on paved and unpaved
roads. Non-road mobile sources include aircraft and related support
vehicles, locomotives, construction equipment, agricultural equipment,
mobile equipment, and recreational vehicles.
In the West Pinal County PM10 Plan, the State based the
point source emissions for the 2008 base year emissions inventory on
reported data from facilities using the permit file reporting programs
of the Pinal County Air Quality Control District (PCAQCD). Area
sources, as noted above, include smaller emissions sources distributed
across the nonattainment area. ADEQ estimated emissions for area
sources using established inventory methods, including publicly
available emissions factors and activity information. The State derived
activity data from national survey data, such as the Energy Information
Administration or from local sources and PCAQCD databases. Emissions
factors used for the estimates come from many sources, such as facility
and equipment source tests, compliance reports, and the EPA's
compilation of emissions factors document known as ``AP-42.''
ADEQ calculated the 2008 base year on-road emissions inventories in
the West Pinal PM10 Plan using the MOVES2014 model and a
back-casting of 2015 modeling of vehicle travel activity data provided
by MAG.\20\ ADEQ estimated emissions inventories for non-road equipment
using the EPA's NONROAD Model, including construction and mining
equipment, industrial and commercial equipment, lawn and garden
equipment, agricultural equipment, and recreational vehicles.\21\
Locomotive emissions were estimated from EPA published emission factors
and local track-mileage, train speed, and throughput data.\22\ The
State developed aircraft and related ground support vehicle emissions
estimates in conjunction with activity data from local airports in the
region.
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\20\ Appendix B, 62-75.
\21\ Appendix B, 87-90. EPA NONROAD Model, Version 2008a,
released July 2009.
\22\ Appendix B, 96.
---------------------------------------------------------------------------
As described previously, the State grouped direct PM10
emissions estimates in the West Pinal County PM10 Plan into
two general categories and emissions inventories, windblown dust and
human activity-based emissions; \23\ we present these inventories in
Tables 1 and 2, respectively. In general, emission inventories can be
broken into four basic categories: Stationary sources, area sources,
non-road sources and mobile sources. Instead of a summary emissions
inventory consisting of these four general categories, ADEQ provided a
more detailed 2008 base year emissions inventory. In some cases, a
source category will appear in both emissions inventories and tables.
For example, an unpaved road and an agricultural field will emit
PM10 when wind speeds become high enough to pick up and
carry disturbed earth, as well as due to vehicle and equipment traffic
on the unpaved road or agricultural activity in a field, such as
harvesting or tilling.
---------------------------------------------------------------------------
\23\ Tables 5-1, 5-2, and 5-3, West Pinal County PM10
Plan.
Table 1--West Pinal County PM10 Plan, Windblown Dust/Fugitive Emissions
Inventory
[Tons per year]
------------------------------------------------------------------------
2008 base
Source category year
------------------------------------------------------------------------
Developed Urban Lands....................................... 200.7
Developed Rural Lands....................................... 1,959.7
Unpaved Roads............................................... 4,688.6
Cleared Areas............................................... 398.1
Residential Construction.................................... 1,302.4
Dairies..................................................... 449.6
CAFOs....................................................... 273.7
Desert Shrubland............................................ 38,276.7
Agriculture................................................. 19,510.1
Commercial Construction..................................... 686.4
Other....................................................... 4,243.9
Site Development............................................ 858.7
-----------
Total................................................... 72,848.6
------------------------------------------------------------------------
Source: West Pinal County PM10 Plan, Table 5-3; Appendix B, Tables 5-31,
5-33.
Table 2 presents ADEQ's direct PM10 emissions inventory related to
human activity. Stationary sources are broken out into permitted
sources and fuel combustion. Area sources are disaggregated into
several source categories: Fires, open burning, unpaved parking, and
construction sites and activities. Agricultural sources are also
disaggregated into several source categories: on field harvesting, on
field tilling, confined animal feed operations (CAFOs), and dairies. In
contrast, mobile sources are included within the ``unpaved roads'' and
``paved roads'' source categories. Each of these two source categories
aggregate direct (vehicle exhaust, tire and brake wear) and fugitive
PM10 emissions from motor vehicles on unpaved and paved
roads. Finally, nonroad equipment and railroad emissions are assigned
to their own respective source categories.
Table 2--West Pinal County PM10 Plan, Human Activity-Based Emissions
Inventory
[Tons per year]
------------------------------------------------------------------------
2008 base
Source category year
------------------------------------------------------------------------
Ag Fields--Harvesting....................................... 312.9
Ag Fields--Tilling.......................................... 2,540.3
CAFOs....................................................... 2,614.3
Paved Road *................................................ 1,180.7
Unpaved Road--All Road Types *.............................. 45,127.8
Fuel Combustion............................................. 28.3
Fires....................................................... 19.9
Open Burning................................................ 13.6
Nonroad..................................................... 121.3
Railroad.................................................... 85.9
Construction................................................ 12,955.3
Dairy....................................................... 186.6
Permitted Sources........................................... 781.3
Unpaved Parking............................................. 251.5
-----------
Total................................................... 66,219.7
------------------------------------------------------------------------
Source: West Pinal County PM10 Plan, Table 5-3; Appendix B, Tables 5-31,
5-33.
* Paved and Unpaved Road emissions estimates include direct vehicle
emissions and fugitive dust emissions from vehicle re-entrainment.
Tables 1 and 2 provide a summary of the West Pinal County 2008 base
year direct PM10 emissions in tons per year. Appendix B,
Chapters 3 and 5 also provide source category estimates in a pounds per
day format consistent with the 24-hour PM10 NAAQS. Where
appropriate, within the attainment demonstration, ADEQ used these daily
estimates or developed more focused daily emissions estimates to
provide the basis for the control measure analysis and the modeled
attainment demonstrations in the West Pinal County PM10
Plan.\24\ Within the windblown PM10 emissions inventory, the
largest source after desert shrubland
[[Page 1352]]
is agricultural emissions. Within the human activity-based emissions
inventory, the largest source is unpaved roads, followed by
construction fugitive emissions.
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\24\ Appendix B, chapters 3 and 5.
---------------------------------------------------------------------------
3. The EPA's Review of the State's Submission
We have reviewed the 2008 base year emissions inventory for direct
PM10 in the West Pinal County PM10 Plan and
emissions inventory estimation methodologies used by ADEQ for
consistency with CAA requirements and EPA guidance. We address the
State's analysis for PM10 precursors in Section III.B.
First, we find that although the 2008 base year inventory reports
annual PM10 emissions estimates, the Plan also provides and
uses daily emissions estimates within the attainment demonstration
modeling and the related modeling domain micro-emissions inventories;
therefore, the Plan is consistent with the requirement that ADEQ must
use an emissions inventory in a form consistent with the 24-hour
PM10 standard.\25\ ADEQ has provided adequate documentation
explaining how it calculated the 2008 base year emissions estimates,
both as annual and daily inventories.\26\
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\25\ As discussed in Section III.G Motor Vehicle Emissions
Budgets and Transportation Conformity, an annual emissions inventory
introduces difficulties with determining and presenting a motor
vehicle emissions budget.
\26\ Chapter 5 and Appendix B of the West Pinal County
PM10 Plan.
---------------------------------------------------------------------------
Second, we find that the 2008 base year emissions inventory in the
West Pinal County PM10 Plan used emissions models, emission
factors, and methodologies for estimating PM10 emissions
that were accurate and appropriate to the time that the Plan was
written. Also, the 2008 base year inventory for direct PM10
is comprehensive in scope and coverage. Therefore, the submitted
emissions inventory represents a comprehensive, accurate, and current
inventory of actual emissions of direct PM10 during that
year in the West Pinal County Area.
Third, we find that ADEQ's selection of 2008 for the base year
emissions inventory is appropriate because it is chosen from one of the
three years, 2006-2008, in which the area was designated nonattainment.
The 2008 emissions inventory is representative of the sources of direct
PM10 pollution contributing to exceedances of the
PM10 NAAQS that caused the area to be designated
nonattainment. Consequently, the EPA is proposing to approve the 2008
base year emissions inventory for direct PM10 in the West
Pinal County PM10 Plan as meeting the requirements for a
base year inventory set forth in CAA section 172(c)(3).
B. PM10 Precursors
1. Statutory and Regulatory Requirements
Section 189(e) of the Act requires that the control requirements
for major stationary sources of direct PM10 also apply to
major stationary sources of PM10 precursors, except where
the Administrator determines that such sources do not contribute
significantly to PM10 levels that exceed the standard in the
area. While CAA section 189(e) expressly requires control of precursors
from major stationary sources, subpart 4 and other CAA provisions
collectively require the control of direct PM10 and
PM10 precursors from all types of sources (i.e., stationary
sources, area sources and mobile sources) as may be needed for the
purposes of demonstrating attainment as expeditiously as practicable in
a given nonattainment area.\27\
---------------------------------------------------------------------------
\27\ See CAA requirements for states to demonstrate attainment
``as expeditiously as practicable,'' CAA section 188(c)(1) and
section 172(a)(1).
---------------------------------------------------------------------------
The provisions of subpart 4 of part D, title I of the CAA do not
define the term ``precursor'' for purposes of PM10, nor do
they explicitly require the control of any specific PM precursor. The
statutory definition of ``air pollutant'' in CAA section 302(g),
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.'' EPA has identified sulfur
dioxide (SO2), oxides of nitrogen (NOX), volatile
organic compounds (VOC), and ammonia (NH3) as precursors to
the formation of PM.\28\ Accordingly, a state must include emissions of
direct PM emissions and these four precursors in emissions inventories
and must control emissions from sources of all of these pollutants,
unless the state demonstrates to EPA's satisfaction that control of one
or more of these pollutants is not needed for expeditions attainment of
the NAAQS in the nonattainment area at issue.
---------------------------------------------------------------------------
\28\ See 81 FR 58010, 58018.
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2. Summary of the State's Submission
Appendix B, Exhibit BXVI contains ADEQ's demonstration that
emissions of SO2, NOX, and NH3 from
existing sources in the West Pinal County nonattainment area do not
contribute significantly to PM10 levels that exceed the
NAAQS. For this analysis, ADEQ estimated the impact of these three
PM10 precursors on PM10 concentrations at two
sites, Cowtown (CWT) and Pinal County Housing (PCH), using ``worst
impact day monitored data'' from a year-long chemical mass balance
characterization (CMBC) study (Desert Southwest Coarse Particulate
Matter Study) and emissions data from the 2008 National Emission
Inventory (NEI).\29\ ADEQ evaluated these data to determine which, if
any, source categories had precursor emissions that contribute more
than 5 micrograms per cubic meter ([micro]g/m\3\) on specific design
days. \30\
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\29\ Clements, A.L., Fraser, M.P., Upadhyay, N., Herckes, P.,
Sundblom, M., Lantz, J., and Solomon, P.A., ``Chemical
characterization of coarse particulate matter in the Desert
Southwest--Pinal County Arizona, USA'', Atmospheric Pollution
Research, 5 (2014) 52-61.
\30\ ADEQ focused their attainment demonstration on a set of
``design days'' and monitors that have experienced, or are conducive
to, the highest concentrations. See EPA TSD, p. 11. Two design days
were examined in ADEQ's PM10 precursor demonstration.
---------------------------------------------------------------------------
Appendix B, Exhibit BXVI, Table BXVI-1 provides the maximum
particle mass concentration and chemical composition (i.e., crustal,
organic material, nitrate, sulfate, ammonium, other species, and
unidentified particle fractions) measured during the CMBC study for CWT
and PCH. ADEQ then calculated the percentage of each chemical
constituent to the summed total of the chemical constituent parts. ADEQ
assumed the design days for each monitor had the same relative chemical
composition as the ``worst impact day'' identified in the CMBC study.
The State calculated design day concentrations for each chemical
constituent by multiplying the study-derived percentages by a design
day concentration for CWT (244.5 [mu]g/m\3\) and PCH (178.0 [mu]g/
m\3\). The CMBC study estimated that summed nitrate, sulfate, and
ammonium impacts on the CWT and PCH monitors were 3.4 percent and 4.0
percent, respectively. These percentages suggest that 8.4 [mu]g/m\3\
and 7.2 [mu]g/m\3\ of the design day ambient PM10
concentrations at the CWT and PCH monitors resulted from emissions of
the three PM10 precursors examined.
Next, ADEQ processed Pinal County 2008 EPA NEI reported emissions
for NOX, SO2, and NH3 to determine the
percent contribution of each source sector to the total emissions of
these pollutants for the county. \31\ ADEQ apportioned the precursor
concentrations derived above to individual source sectors based on the
relative contribution of each sector to the annual emission inventory.
Based
[[Page 1353]]
on this analysis, no precursor emissions from any source category
exceeded the 5 [mu]g/m\3\ threshold.\32\ The largest contributing
source category was ``On-road Mobile,'' contributing less than 3.5
[mu]g/m\3\ of PM10 from precursor emissions to either
monitor on the design days.
---------------------------------------------------------------------------
\31\ Appendix B, Exhibit BXVI, Table BXVI-2.
\32\ Appendix B, Exhibit BXVI, Table BXVI-3.
---------------------------------------------------------------------------
3. The EPA's Review of the State's Submission
We identified several issues with the analysis that ADEQ presented.
First, SO2, NOX, VOC, and ammonia are precursors
to the formation of PM10. ADEQ does not address VOC
emissions in its analysis; therefore, we cannot evaluate whether
sources of VOC emissions contribute significantly to PM10
levels that exceed the NAAQS in the West Pinal County PM10
nonattainment area.
Second, it is unclear whether the chemical composition values
presented in Appendix B, Exhibit BXVI, Table BXVI-1 reflect one maximum
day sample, or the maximum chemical composition measured for each
individual component during the entire CMBC study. If the latter
approach was used, then the resulting percentages would not reflect
percentages measured on any actual exceedance day and could
overrepresent or underrepresent the various chemicals when compared to
actual exceedance days. If the chemical composition values represent
one maximum day sample, then: (a) The individual components listed in
Table BXVI-1 when totaled together should equal that day's total mass,
which they do not; and (b) this would only represent a single day--
therefore, a single type of exceedance day. ADEQ modeled two
meteorological scenarios causing exceedances, high wind conditions and
stagnant or low wind conditions. The emission sources affecting the
PM10 composition would vary between these two scenarios,
making use of a single maximum value at each site for each chemical
component likely insufficient. Therefore, ADEQ's approach of assuming
the chemical composition of the two design days match those reported in
the study likely does not address all conditions affecting
nonattainment for the area.
Third, ADEQ applied the 5 [mu]g/m\3\ threshold from the Serious
PM10 nonattainment area addendum to the General
Preamble.\33\ The Serious area addendum states that, for purposes of
evaluating best available control measures (BACM), a source category
will be presumed to contribute significantly to a violation of the
NAAQS if its PM10 impact at the location of the expected
violation would exceed 5 [mu]g/m\3\. This guidance is not precursor
guidance and was intended to apply to the total impact of a source
category (including direct PM and precursor emissions). It is not clear
from the State's submission why the application of this threshold to
the impact of precursor emissions from individual source categories is
an appropriate method of evaluating the significance of PM10
precursor emissions for the West Pinal County PM10
nonattainment area.\34\
---------------------------------------------------------------------------
\33\ Appendix B, Exhibit BXVI, BXVI-2. See 59 FR at 42011.
\34\ For more recent guidance on precursor significance, see
Memorandum from Scott Mathias, Acting Director, Air Quality Policy
Division and Richard Wayland, Director, Air Quality Assessment
Division, ``Fine Particulate Matter (PM2.5) Precursor
Demonstration Guidance'' (May 30, 2019).
---------------------------------------------------------------------------
Finally, ADEQ used an annual inventory to partition the source
category contribution to PM10. High wind affected days would
likely have a different composition of sources than what would be
reflected in an annual inventory, potentially by a substantial margin.
ADEQ did not address this issue, and used the annual inventory
composition to represent all exceedance days.
The State has not adequately shown that PM10 precursors
do not contribute significantly to concentrations above the NAAQS in
the West Pinal County PM10 nonattainment area. As described
elsewhere in this notice, due to the deficiencies with the State's
precursor analysis, the State has not shown that it was unnecessary to
regulate emissions of precursors in its RACM and modeled attainment
demonstration. As explained in Section III.C., the State has only
evaluated sources of direct PM emissions within the West Pinal County
PM10 Plan. The EPA anticipates that ADEQ could develop an
improved precursor analysis for the area, and this analysis may
ultimately confirm that it is not necessary to regulate one or all of
the PM10 precursors; however, we find that the precursor
analysis submitted with the Plan does not provide a sufficient basis
for that conclusion.
In conclusion, because of the omissions and uncertainties in ADEQ's
PM10 precursor analysis, we are unable to determine whether
precursor emissions contribute significantly to PM10 levels
that exceed the NAAQS in the West Pinal County nonattainment area.
Consequently, we are proposing to disapprove the precursor
demonstration in the West Pinal County PM10 Plan because the
demonstration is inadequate to show that emissions reductions from all
PM10 precursors do not contribute significantly to
PM10 levels exceeding the NAAQS, as required by CAA Section
189(e). As explained in section III.C, the deficiencies in the State's
precursor analysis mean that the State failed to establish in its RACM/
RACT analysis that it was unnecessary to regulate PM10
precursor emissions.
C. Reasonably Available Control Measures Demonstration
1. Statutory and Regulatory Requirements
CAA section 172(c)(1) requires that each attainment plan provide
for the implementation of all RACM/RACT as expeditiously as practicable
(including such reductions in emissions from sources in the area
through implementation of reasonably available control technology) and
for attainment of the NAAQS. Consistent with section 189(a)(1)(C), each
state with a Moderate PM10 nonattainment area is required to
submit provisions to assure implementation of reasonably available
control measures no later than 4 years after the date of designation of
the area. Taken together, these CAA provisions require that Moderate
area attainment plans must provide for the implementation of RACM and
RACT in the nonattainment area as expeditiously as practicable but no
later than 4 years after designation.
Section 189(a)(1)(B) of the CAA requires states to demonstrate
attainment of the PM10 standard by the applicable attainment
date (or demonstrate that attainment by such date is impracticable) and
Section 188(c)(1) requires that the attainment date for a Moderate area
shall be as expeditiously as practicable, but no later than the end of
the sixth calendar year after the year of the nonattainment area's
designation.
To address this requirement to adopt all RACM/RACT and meet the
PM10 NAAQS as expeditiously as practicable, states should
consider all potentially reasonable control measures for source
categories in the nonattainment area to determine whether they are
reasonably available for implementation in that area and whether they
would, if implemented individually or collectively, advance the area's
applicable attainment date by one year or more.\35\ Any measures that
are necessary to meet these requirements that are not either federally
promulgated, or part of the state's SIP, must be submitted in
enforceable form
[[Page 1354]]
as part of the state's nonattainment plan SIP submission for the area.
---------------------------------------------------------------------------
\35\ 44 FR 20372 (April 4, 1979) and 57 FR 13498 (April 16,
1992).
---------------------------------------------------------------------------
The EPA has provided guidance interpreting the RACM requirement in
the General Preamble for the Implementation of the Clean Air Act
Amendments of 1990 (``General Preamble''). This guidance includes the
following elements and concepts: A recommended list of potential
PM10 measures for states to consider; \36\ an emphasis on a
state's evaluation of the technological and economic feasibility of
potential control measures to determine if such measures are reasonably
available for implementation in a given nonattainment area; an
expectation that the state will provide a reasoned explanation for a
decision not to adopt a given control measure, including a review of
any control measures recommended to the state during public comment or
public hearing; and, a discussion that in some cases partial
implementation of an emissions reduction program may be considered RACM
when full implementation would be infeasible within the given Moderate
area timeframe.\37\
---------------------------------------------------------------------------
\36\ 57 FR 18070.
\37\ 57 FR 13540, 13541.
---------------------------------------------------------------------------
2. Summary of the State's Submission
For the West Pinal County PM10 Plan, ADEQ worked through
a process to identify and evaluate potential RACM/RACT that could
contribute to expeditious attainment of the PM10 NAAQS in
the West Pinal County nonattainment area. Chapter 6 of the West Pinal
County PM10 Plan provides an overview and description of the
Plan's constituent control measures. ADEQ's RACM/RACT analysis for the
PM10 standard is described in Appendix F--RACM Analysis for
the West Pinal County PM10 Nonattainment Area (``Appendix
F''). Appendix F contains summary analyses of potential control
measures for emissions reduction opportunities, as well as the economic
and technological feasibility and comparability with control
requirements in other states and localities.
As a first step in the RACM/RACT analysis, ADEQ prepared a detailed
inventory of direct PM10 emissions sources to identify
source categories from which emissions reductions would contribute to
attaining the PM10 standard.\38\ In this analysis, ADEQ
identified point sources, unpaved roads and agriculture on tribal land,
dairy operations, nonroad vehicles, residential fuel combustion, and
open burning as insignificant sources of emissions in the area.\39\
Then, ADEQ identified agricultural operations, confined animal feeding
operations, fugitive dust from cleared area and unpaved parking lots,
construction fugitive dust, and re-entrained dust from paved and
unpaved roads as significant sources in the nonattainment area and
determined a list of available control measures. ADEQ determined that a
source category was significant if those sources contributed more than
5 [mu]g/m\3\ on a 24-hour basis on a given design day. Conversely, ADEQ
determined that source categories contributing less than the 5 [mu]g/
m\3\ threshold were insignificant; furthermore, ADEQ determined these
insignificant sources would not advance attainment of the NAAQS, given
their small collective contribution to nonattainment.\40\ Finally, ADEQ
evaluated the efficacy, cost, and technical feasibility of these
identified control measures within the nonattainment area.\41\ As part
of this review, ADEQ also compared the control requirements of its
proposed rules with those requirements in other PM10
nonattainment areas or similar state and local provisions.\42\ ADEQ did
not identify sources or analyze potential RACM/RACT for PM10
precursors because it concluded that such precursors did not contribute
significantly to a violation of the NAAQS.
---------------------------------------------------------------------------
\38\ Appendix F, Chapters 2 and 3.
\39\ Appendix F, 4-12.
\40\ Appendix F, Chapter 2 and Table 1.
\41\ Appendix F, Chapters 2-4.
\42\ Appendix F, Chapter 4; Exhibit F-I, Available Measures;
Exhibit F-II, Construction Comparison; Exhibit F-III, Agricultural
Comparison; and, Exhibit F-IV, Fugitive Dust Comparison.
---------------------------------------------------------------------------
With this process, ADEQ attempted to evaluate and analyze the
universe of potential RACM/RACT level controls for sources of direct
PM10 emissions and identify the subset of control measures
that were available to include within the West Pinal County
PM10 Plan. ADEQ identified a set of control measures that it
determined would be sufficient to enable the area to attain by December
31, 2018, and additional controls that it determined were not necessary
for attainment or RFP to serve as contingency measures.\43\ ADEQ based
this conclusion on: (1) The practical feasibility of adopting control
measures over the latter half of 2015 with the State's desired
implementation date of no later than January 1, 2016; and (2) the
ability of these control measures to produce immediate emissions
reductions and contribute to attainment of the PM10 NAAQS by
2018.\44\ As discussed earlier, the State submitted the following
control measures with the West Pinal County PM10 Plan: The
AgBMP Rules for Pinal County, the Pinal County Fugitive Dust Rule, and
the Pinal County Construction Dust Rule. ADEQ relied only on the
following portions of the AgBMP Rules for Pinal County to meet the
RACM/RACT requirements and demonstrate attainment of the
PM10 standard: AgBMP rule R18-2-610 and -610.03, commercial
farms; AgBMP rule R18-2-611 and -611.03, commercial animal operations
(except for dairy operations); and R18-2-612 and -612.01, irrigation
districts.\45\
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\43\ West Pinal County PM10 Plan, Chapter 7; Table 7-
4; Appendix D, Table D5-1.
\44\ Appendix F, 29, 47, 51.
\45\ West Pinal County PM10 Plan, Chapters 6 and 7.
---------------------------------------------------------------------------
ADEQ did not provide a complete or systematic analysis of whether
the control measures it did not adopt based on concerns about a lack of
immediate emission reduction effect, if taken together, would advance
the area's attainment date. Nonetheless, ADEQ did adopt those control
measures, implemented them over the 2016-2018 timeframe, and allocated
them to serve as contingency measures in the Plan. ADEQ designated the
portion of the AgBMP Rules for Pinal County applicable to dairy
operations (R18-2-611 and -611.03), along with the Pinal County
Fugitive Dust Rule and the Pinal County Construction Dust Rule, as
contingency measures because these rules provided additional emissions
reductions not relied upon within the Plan's attainment
demonstration.\46\
---------------------------------------------------------------------------
\46\ West Pinal County PM10 Plan, Chapter 6; Chapter
7, Table 7-4.
---------------------------------------------------------------------------
3. The EPA's Review of the State's Submission
As described above, ADEQ evaluated a wide range of potentially
available measures for the West Pinal County PM10 Plan. ADEQ
identified portions of the AgBMP Rules for Pinal County as RACM/RACT
and the State adopted them to provide for attainment of the
PM10 standard.\47\ The remaining adopted control measures,
some of which were identified as significant sources and potential
RACM/RACT, were assigned to provide for contingency measures within the
Plan.\48\ In sum, all source categories identified as significant were
covered by controls either as a control measure for attainment, or as
contingency measures, and implemented over the 2016-2018 timeframe. As
has been confirmed by subsequent monitoring data, however,
[[Page 1355]]
these adopted control measures were insufficient to attain the
PM10 NAAQS by the applicable attainment date, in part
because the State overestimated the effectiveness of the RACM/RACT-
designated adopted controls. As an example, ADEQ assumed high and
insufficiently conservative compliance rates for agricultural
operations that had either no previous experience implementing control
measures, or little to no reliable documented compliance history. We
review the State's analysis and attainment demonstration in Section
III.D and provide detailed discussion in the Technical Support Document
(TSD).
---------------------------------------------------------------------------
\47\ West Pinal County PM10 Plan, Chapters 6 and 7.
\48\ West Pinal County PM10 Plan, Chapter 6; Chapter
7, Table 7-4.
---------------------------------------------------------------------------
The Plan described the adopted control measures and concluded that
a subset was reasonable and would achieve the NAAQS by the attainment
date; therefore, the State concluded that the RACM/RACT-designated
subset of adopted control measures constituted the necessary RACM/RACT
for the area.\49\ The State adopted several additional measures beyond
the RACM/RACT measures to serve as contingency measures in the Plan. If
the RACM/RACT-designated adopted controls actually sufficed to achieve
attainment, then these control measures could have constituted
sufficient RACM, as additional measures beyond those necessary for
attainment need not necessarily be considered as RACM/RACT.\50\ Because
the adopted controls designated as RACM/RACT in the West Pinal County
PM10 Plan were insufficient, however, to achieve attainment,
due in part to overestimates of the control efficiency of these rules,
we find that the State terminated its RACM/RACT analysis prematurely.
The control measures reserved for contingency measures that the State
did not include as RACM/RACT should have been included and justified as
RACM. Furthermore, because the State's determination regarding
PM10 precursors failed to demonstrate that precursors do not
contribute significantly to a violation of the NAAQS, the State remains
obligated to demonstrate that additional PM10 precursor
control measures are not required RACM/RACT.
---------------------------------------------------------------------------
\49\ Appendix F, Chapter 4.
\50\ See 81 FR 58010, 58035. Although such controls should be
evaluated to determine if their adoption could advance attainment.
---------------------------------------------------------------------------
Despite the RACM/RACT-designated rules and contingency measures
adopted and implemented by the State, we find that the State failed to
adopt RACM/RACT sufficient to achieve the PM10 NAAQS, due in
part, to overestimating the control effectiveness of these RACM/RACT
control measures. Our conclusion is confirmed by the failure of the
Plan's adopted and designated measures to result in attainment of the
PM10 NAAQS by the applicable attainment date of December 31,
2018. Because the adopted controls were insufficient to meet the
PM10 NAAQS by the attainment date, and the State excluded
source categories, including sources of precursors, from its RACM/RACT
demonstration without sufficient justification, we propose to
disapprove the RACM/RACT demonstration in the West Pinal County
PM10 Plan and determine that the Plan does not provide for
the implementation of all RACM/RACT as required by CAA section
172(c)(1) and section 189(a)(1)(C).
D. Attainment Demonstration
1. Statutory and Regulatory Requirements
Section 189(a)(1)(B) of the CAA requires that a plan for a Moderate
PM10 nonattainment area include a ``demonstration (including
air quality modeling) that the plan will provide for attainment [of the
PM10 NAAQS] by the applicable attainment date.'' An
attainment demonstration consists of several elements including
technical analyses, such as base year and future year modeling, to
locate and identify sources of emissions that are contributing to
violations of the PM10 NAAQS within the nonattainment area
(i.e., analyses related to the emissions inventory for the
nonattainment area and the emissions reductions necessary to attain the
standard). Section 188(c)(1) of the CAA requires Moderate areas to meet
the PM10 standard as expeditiously as practicable, but no
later than the sixth calendar year from the area designation.
In addition to reviewing the attainment demonstration modeling and
related analyses, we evaluate the Plan's control strategy and the
efficacy of the Plan's adopted controls to meet the PM10
NAAQS by the applicable date.
2. Summary of the State's Submission
ADEQ applied a form of proportional roll back and dispersion
modeling using a micro-emissions inventory method to model attainment
of the PM10 NAAQS. ADEQ modeled two meteorological scenarios
causing ambient air values in excess of the 24-hour PM10
NAAQS of 150 [mu]g/m\3\, high wind conditions and stagnant or low wind
conditions, at a representative subset of the monitoring sites in the
nonattainment area.\51\ Under ``stagnation'' conditions, wind speeds
are typically below 3 mph and particles accumulate in the air without
any meteorological reprieve. Under ``high wind'' conditions, elevated
wind speeds (e.g., over 12 mph) generate dust from disturbed soil
surfaces, elevating PM10 concentrations. Each selected
monitoring site in each modeling scenario had design day specific
micro-emissions inventories consistent with the chosen areal modeling
domain and application. ADEQ calculated the 2008 Base, 2018 Base, and
2018 Attainment micro-emissions inventories for the given requirements
of the modeling application at the respective monitoring site domain
and meteorological day scenario.
---------------------------------------------------------------------------
\51\ West Pinal PM10 Plan County, Section 7.1.
---------------------------------------------------------------------------
The State's attainment demonstration approach is described in the
Plan within the following documents: Chapter 7, ``Attainment
Demonstration and Reasonable Further Progress''; Appendix A, ``Pinal
County PM Inventory Preparation Plan'' (``IPP''); Appendix B, ``Pinal
County PM10 Nonattainment Area Emissions Inventories for
2008 and 2018 Base Years and Design Days'' (``Modeling EI''); Appendix
C, ``Pinal County PM10 Nonattainment Area Source
Apportionment Modeling for 2008 and 2018 Base Scenario Design Days''
(``Modeling TSD''); and, Appendix D, ``Pinal County PM10
Nonattainment Area 2018 Attainment Demonstration and Controlled
Emissions Inventories.''
The West Pinal County PM10 Plan discusses the control
strategy within Chapter 6 of the Plan and in more detail within
Appendix D of the Plan.
a. Modeling
As noted, the West Pinal County PM10 Plan's attainment
demonstration considers two specific problems contributing to
nonattainment of the PM10 standard in West Pinal County: (1)
PM10 emissions from windblown dust and human activity on
days with elevated wind speeds; and (2) PM10 emissions from
human activity, particularly on days with very low wind or ``stagnant''
meteorological conditions.
ADEQ developed a high wind day scenario for Cowtown,
Maricopa, Pinal County Housing, and Stanfield monitors and surrounding
area micro-emissions inventories. Each monitor has its own two domain
micro-emissions inventory for modeling: High wind hours/windblown dust;
and, low wind hours/activity-based emissions. The high wind scenario
used a proportional rollback approach that accounts for the timing
[[Page 1356]]
and geographic location of emissions contributing to NAAQS
exceedances.\52\
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\52\ The term ``rollback'' refers to the assumption that the
PM10 concentrations are directly proportional to
emissions. To predict the ambient effect of an emissions change, the
concentration can be scaled, or ``rolled back,'' by the same
percentage by which emissions are reduced. In ``proportional
rollback,'' each source category is rolled back separately, since
emissions from each will have a different level of control, and in
general a different degree of dispersion. As in simple rollback, the
ambient contribution of each individual source category scales with
its emissions. For the ``weighted proportional rollback,'' source-
to-monitor distance was accounted for via an inverse distance factor
(1/d). For example, a source with only small emissions may
nevertheless have a large contribution to the concentration if it
was very close to the monitor. A change in a source's emissions
causes a change in total concentration in proportion to that
source's contribution to that particular monitor.
---------------------------------------------------------------------------
ADEQ developed a stagnation day scenario for Cowtown,
Pinal County Housing, and Stanfield monitors and surrounding area
micro-emissions inventories. The stagnant day scenarios used dispersion
modeling from the American Meteorological Society (AMS)/EPA Regulatory
Model (AERMOD). ADEQ chose design days from the fall season, September
through November 2008 for this analysis.
b. Control Strategy for Attainment
ADEQ relied on the following portions of the AgBMP Rules for Pinal
County to provide for attainment of the PM10 standard: R18-
2-610 and -610.03, commercial farms; AgBMP rule R18-2-611 and -611.03,
commercial animal operations (except for dairy operations); and, R18-2-
612 and -612.01, irrigation districts.\53\ Tables 3 and 4 show the
annual nonattainment area emissions inventories for the 2018 baseline
estimate and the 2018 attainment estimate by source category and the
control strategies' predicted emissions reductions. Within the
windblown fugitive dust emissions inventories, ADEQ predicted almost
all the emission reductions, 93 percent, to come from soil
stabilization control measures on agricultural land. Within the
activity-based emissions inventories, ADEQ predicted most of the
emission reductions, 87 percent, to come from control measures applied
to unpaved road operations on private agricultural land and canal
roads; the remainder of predicted emission reductions come from control
measures to reduce PM10 emissions from on-field agriculture
and animal feeding operations. As noted, the regulatory vehicle for
these emissions reductions is the AgBMP rule provisions the State
relied on to provide for attainment of the PM10 standard and
to implement RACM/RACT in the area.
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\53\ West Pinal County PM10 Plan, Chapters 6 and 7.
Table 3--Windblown Dust/Fugitive Emissions, 2018 Base and Attainment Emissions Inventories With Estimated
Emission Reductions
[tpy]
----------------------------------------------------------------------------------------------------------------
Source category Base 2018 Attainment 2018 Emission reductions
----------------------------------------------------------------------------------------------------------------
Developed Urban Lands................................... 248.1 248.1 ....................
Developed Rural Lands (low density)..................... 1,959.7 1,959.7 ....................
Unpaved Roads........................................... 4,653.0 3,803.1 849.9
Cleared Areas........................................... 457.0 457.0 ....................
Residential Construction................................ 837.5 837.5 ....................
Dairies................................................. 449.6 449.6 ....................
CAFOs................................................... 155.2 125.3 29.9
Desert Shrubland........................................ .............. ................ ....................
Agriculture............................................. 19,510.1 7,122.0 12,388.1
Commercial Construction................................. 441.4 441.4 ....................
Other................................................... 4,243.9 4,243.9 ....................
Site Development........................................ 552.2 552.2 ....................
-------------------------------------------------------
Total............................................... 33,507.7 20,239.8 13,267.9
----------------------------------------------------------------------------------------------------------------
Source: West Pinal County PM10 Plan, Table 5-3; Appendix B, Tables 5-31, 5-32, 5-33, 5-34.
Table 4--Activity Based Emissions, 2018 Base and Attainment Emissions Inventories With Estimated Emission
Reductions
[tpy]
----------------------------------------------------------------------------------------------------------------
Source category Base 2018 Attainment 2018 Emission reductions
----------------------------------------------------------------------------------------------------------------
Ag--Harvesting.......................................... 312.9 207.1 105.8
Ag--Tilling............................................. 2,540.3 1,658.0 882.3
CAFOs................................................... 1,620.6 1,369.2 251.4
Paved Road *............................................ 1,408.0 1,408.0 ....................
Unpaved Road *.......................................... 45,105.3 37,186.4 7,918.9
Fuel Combustion......................................... 34.9 34.9 ....................
Fires................................................... 22.2 22.2 ....................
Open Burning............................................ 16.8 16.8 ....................
Nonroad................................................. 144.4 144.4 ....................
Railroad................................................ 45.4 45.4 ....................
Construction............................................ 8,499.8 8,499.8 ....................
Dairy................................................... 184.0 184.0 ....................
Permitted Sources....................................... 781.3 781.3 ....................
Unpaved Parking......................................... 251.5 251.5 ....................
-------------------------------------------------------
Total............................................... 60,967.4 51,809.0 9,158.4
----------------------------------------------------------------------------------------------------------------
Source: West Pinal County PM10 Plan, Table 5-3; Appendix B, Tables 5-31, 5-32, 5-33, 5-34
* Paved and Unpaved Road emissions estimates include direct vehicle emissions and fugitive dust emissions from
vehicle re-entrainment.
[[Page 1357]]
The State adopted and pre-implemented control measures to meet the
contingency measures requirement within the Plan: The portion of the
AgBMP Rules for Pinal County applicable to dairy operations (R18-2-611
and -611.03), along with the Pinal County Fugitive Dust Rule and the
Pinal County Construction Dust Rule.\54\ We address the contingency
measures requirement of the Act more completely in Section III.F, where
we point out that pre-implemented contingency measures are not
approvable under CAA section 172(c)(9). Here, we mention the control
measures, adopted and subsequently implemented as contingency measures,
to emphasize two points: (1) Given the shortfall in attaining the
PM10 NAAQS, these control measures designated for
contingency should have been evaluated and designated RACM/RACT, as we
discussed in Section III.C; and (2) despite implementing the RACM/RACT
control measures for attainment and the designated contingency
measures, the West Pinal County area still failed to attain the
PM10 NAAQS, by a large margin.
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\54\ West Pinal County PM10 Plan, Chapter 6; Chapter
7, Table 7-4.
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3. The EPA's Review of the State's Submission
As previously discussed, the EPA issued a finding that the West
Pinal County area failed to attain the PM10 NAAQS by the
outermost statutory attainment date of December 31, 2018.\55\ In
addition to our previous regulatory review of the air monitoring data
from 2016-2018, detailed in our June 24, 2020 notice, we reviewed
ambient air monitoring data collected from 2006-2018 to examine
PM10 values over time and recent trends over the 2016-2018
control strategy period of Plan implementation. Our detailed review of
PM10 data is included in our TSD provided in the docket for
this proposal. We provide two general conclusions from our data review.
---------------------------------------------------------------------------
\55\ 85 FR 37756.
---------------------------------------------------------------------------
First, when considering the number of exceedances of the
PM10 standard, the data show that the West Pinal County
monitoring sites have consistently measured many exceedances in every
year between the start of the base year period, 2006-2008, and in 2018,
the attainment year. While the number of exceedances each year has
generally and gradually decreased over time, there is no clear evidence
of a sustained decrease in recent years as ADEQ implemented control
measures. For example, over the 2016 through 2018 period that would
have been relevant to attainment by December 31, 2018, the annual
number of exceedances of the 24-hour PM10 NAAQS ranged from
29 to 38.\56\ The form of the NAAQS allows for no more than one
exceedance per year, averaged over a three year period. Furthermore,
all eight monitors in the West Pinal County nonattainment area showed
violations of the PM10 NAAQS as determined by their 2018
design values.\57\
---------------------------------------------------------------------------
\56\ See Table 2 in the TSD.
\57\ See Table 1 in the TSD.
---------------------------------------------------------------------------
Second, design value trends show that the number of expected
exceedances remain well above the PM10 NAAQS of one
exceedance per year. The high concentrations and number of exceedances
clearly show that PM10 concentrations well above the level
of the NAAQS (150 [mu]g/m\3\) continue to be a major air quality
problem in the West Pinal County nonattainment area despite the
implementation of control measures meant to reduce PM10
levels. For example, the design concentration for 2016-2018, the period
in which values should be at or under 150 [mu]g/m\3\ to show attainment
by 2018, is 403 [mu]g/m\3\, or 269 percent of the standard.\58\
---------------------------------------------------------------------------
\58\ See Table 3 and further discussion in Section II.B of the
TSD.
Table 5--Three-Year PM10 Monitoring Data Statistics for the Cowtown and Hidden Valley Monitoring Sites a
--------------------------------------------------------------------------------------------------------------------------------------------------------
3-Year period 2006-2008 2007-2009 2008-2010 2009-2011 2010-2012 2011-2013 2012-2014 2013-2015 2014-2016 2015-2017 2016-2018
--------------------------------------------------------------------------------------------------------------------------------------------------------
Design Concentration ([mu]g/ 916 653 539 1064 1064 1064 521 510 \b\ 357 \b\ 303 403
m\3\).........................
3-year Design Value............ 201.2 139.8 86.1 60.7 63 75.7 64 50.5 \b\ 38.3 \b\ 29.8 32.8
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sources: EPA AQS Quick Look Report, December 10, 2020, and EPA AQS Design Value Report, December 10, 2020. The design concentration for these sites is
the 4th highest 24-hour concentration measured over each three-year period, as detailed in Section 6.3.1 of the PM10 SIP Development Guideline, EPA-
450/2-86-001 (June 1987).
\a\ Data collected prior to 2016 were collected from the Cowtown monitoring site; data since 2016 were collected at the Hidden Valley monitoring site,
as described in our TSD, page 6, within the docket for this rulemaking.
\b\ The EPA's relocation approval letter stated that the data from Cowtown and Hidden Valley would be combined to form one continuous data record for
design value calculations. Consequently, the 2014-2016 and 2015-2017 design values are each a composite data record consisting of 2014 and/or 2015
data from the Cowtown monitoring site, and 2016 and/or 2017 data from the Hidden Valley monitoring site, as applicable.
The West Pinal County 2015 PM10 design value was 50.5
exceedances. For the area to meet the PM10 standard by 2018,
it could not have more than three exceedances of the PM10
NAAQS across the three years, 2016-2018, to show a design value of 1.0
exceedances, averaged over three years. Instead, the Plan's control
strategy resulted in the following number of primary exceedances: 30 in
2016; 38 in 2017; and 29 in 2018.\59\ Not only did the Plan's control
strategy fail to produce the effect intended in 2016, the designated
control strategy rules and pre-implemented contingency measures failed
to reduce PM10 exceedances to a level needed to attain the
PM10 standard by December 31, 2018.
---------------------------------------------------------------------------
\59\ TSD, Table 2; EPA AQS Quick Look Report, December 10, 2020,
in the docket for this rulemaking action.
---------------------------------------------------------------------------
Given the ambient monitoring data unequivocally indicate that the
Plan was insufficient to achieve attainment by the 2018 attainment
date, we do not provide an exhaustive evaluation of the attainment
demonstration analyses in the West Pinal County PM10 Plan.
Instead, we focused our review on two major deficiencies that preclude
our approval of this Plan element. Our review of these two deficiencies
is illustrative of the insufficiently conservative analyses or
assumptions underlying the Plan's failed attainment demonstration.
Specifically, we evaluated the ``design days'' ADEQ selected to conduct
the modeling exercises and the specific design day micro-emissions
inventories and rule control effectiveness assumptions ADEQ made to
model the Plan's control strategy within the 2018 attainment modeling
analyses. Next, we provide a short summary of our review. We also
provide a more detailed review in our TSD.
First, we find the design days that ADEQ selected for modeling the
Cowtown monitor under stagnation
[[Page 1358]]
conditions, and several monitors under high wind conditions, were
chosen with inconsistent criteria and/or have data inaccuracies. In
turn, these inconsistencies and inaccuracies led to design day
concentration values that were likely too low to address adequately the
range of exceedances experienced in the nonattainment area. For
example, in selecting the stagnation scenario design day for Cowtown,
ADEQ limited selection to fall 2008 (September to November) exceedance
days despite the higher PM10 concentrations and a comparable
number of exceedance days in the spring season (March to May).
Ultimately, the selected 2008 design day was the 68th highest out of
the 137 total low wind/stagnation exceedance days identified by the
State (i.e., approximately 49% of the low wind/stagnation exceedance
days had higher concentrations than the design day selected).\60\ This
middle range day was insufficiently conservative and was inadequate to
represent the attainment issues during stagnation conditions and to
address the range and severity of exceedances experienced at CWT.\61\
---------------------------------------------------------------------------
\60\ ``Low wind/stagnation exceedance days'' for purposes of
this document are the exceedance days that remain once days
identified by ADEQ as high wind day exceedances in IPP, Appendix C,
Table C-1 are removed. See ``Cowtown 2008 Exceedances.xlxs'' in the
docket for this action.
\61\ See Section III.B.1. of the TSD for our complete review of
design day selection for stagnation scenario at the Cowtown monitor.
Also, see Section III.B.2 of the TSD for our complete review of
design day selection for the high wind scenario.
---------------------------------------------------------------------------
Second, we conclude that several data inputs and assumptions
associated with modeling the control strategy were unsupported,
overstated, or insufficiently conservative leading to an overestimate
of the overall efficacy of the control strategy within the attainment
demonstration. Specifically, in calculating the control effectiveness
of the rules in the control strategy, two component assumptions or
estimates were the primary cause of this overestimate: (1) Rule
effectiveness, i.e., the percentage of compliant facilities; and, (2)
aggregate or net best management practices (BMP) control efficiencies.
For example, we found that despite limited or no compliance data, the
lack of compliance assistance program efficacy figures, the lack of
automatic reporting requirements, and little to no farm experience
implementing BMPs, ADEQ assumed high compliance rates with the AgBMP
rule; in turn, this unjustifiably inflated the overall control
effectiveness calculations. In addition, we found that the domain
modeling micro-emissions inventory estimates that ADEQ derived from
this limited BMP implementation data were not appropriately documented
or supported and were insufficiently conservative due to overly
optimistic or simplifying assumptions used to aggregate BMP control
efficiency estimates, such as assuming that farms will either choose
not to operate or will routinely implement higher cost and higher
control efficiency BMPs on high risk days. Consequently, ADEQ assumed
farms reduced emissions from cropland operations and unpaved roads to a
greater extent than what could be supported by the documentation in the
Plan.\62\
---------------------------------------------------------------------------
\62\ See Section III.C. of the TSD for our complete review of
control effectiveness estimates.
---------------------------------------------------------------------------
Based on our evaluation of the design days and modeling and control
effectiveness assumptions in the Plan, we find that these several
deficiencies in the analyses preclude approval of the attainment
demonstration. In addition, after reviewing past and recent
PM10 data against the West Pinal County PM10
Plan's attainment demonstration predictions, we conclude that:
There is no clear evidence of a sustained decrease in the
number of exceedances in recent years as control measures have been
implemented (2015-2018);
PM10 concentrations well above the level of the
24-hour PM10 NAAQS (150 [mu]g/m\3\) continue to be a major
air quality problem in the West Pinal County nonattainment area despite
the implementation of control measures designed to reduce
PM10 levels thus far; and
The Plan's control strategy, whether considered as adopted
RACM/RACT or as the entire suite of rules submitted with the Plan, was
inadequate to attain the PM10 NAAQS by December 31, 2018, as
evidenced by the ambient PM10 data.
Consequently, we propose to disapprove the modeled attainment
demonstration in the West Pinal County PM10 Plan because it
does not meet the requirements of CAA section 189(a)(1)(B) and section
188(c)(1).
E. Reasonable Further Progress Demonstration
1. Statutory and Regulatory Requirements
The requirement for RFP in PM10 nonattainment areas is
specified in CAA section 172(c)(2) and is described in the General
Preamble.\63\ Under CAA section 171(1), RFP is defined as meaning such
annual incremental reductions in emissions of the relevant air
pollutant as are required under part D (``Plan Requirements for
Nonattainment Areas'') of the CAA or as may reasonably be required by
the EPA for the purpose of ensuring attainment of the applicable NAAQS
by the applicable date. In addition, CAA section 189(c)(1) requires
quantitative milestones that demonstrate RFP and must be achieved every
3 years until the nonattainment area is redesignated to attainment,
beginning 4.5 years after a Moderate area's designation to
nonattainment of the PM10 NAAQS.\64\ Therefore, Moderate
area plans should contain quantitative milestones for 4.5 and 7.5 years
after designation. These quantitative milestones should be constructed
so that they can be tracked, quantified and/or measured adequately, and
provide for an objective evaluation of RFP toward attainment of the
NAAQS, particularly as part of milestone reporting.\65\
---------------------------------------------------------------------------
\63\ 57 FR at 13539.
\64\ Ibid.
\65\ 81 FR 58063-64.
---------------------------------------------------------------------------
2. Summary of the State's Submission
The West Pinal County PM10 Plan discusses how the Plan
provides for RFP in Section 7.2 and Appendix D and provides visual
representation in Figure 7-1 and Figure D 5-1.\66\ For the purposes of
calculating annual increments of emission reductions for RFP, ADEQ
assumed a linear ``glidepath'' with equal annual emissions reductions
over the 2016-2018 implementation timeframe. This annual increment
representing RFP is 7,475 tons per year.\67\ The implementation of the
Plan's control strategy is projected to produce almost all the needed
emissions reductions in the first year, 2016, with slight and
incremental emission reductions to follow in 2017 and 2018. Because
ADEQ projected that most of the emissions reductions would come in the
first year, the projected emissions were below the ``glidepath'' and
ADEQ concluded that RFP was demonstrated.
---------------------------------------------------------------------------
\66\ West Pinal County PM10 Plan, 99 and Figure 7-1,
101; Appendix D, 45.
\67\ West Pinal County PM10 Plan, 100. Expected
emission reductions from 2015 to 2018, 22,426 tons per year, are
divided into 3 annual increments of 7,475 tons per year.
---------------------------------------------------------------------------
3. The EPA's Review of the State's Submission
Based in part on our review of the 2016-2018 ambient data and in
part on the flaws identified in the West Pinal County PM10
Plan attainment demonstration, we find that ADEQ did not adequately
provide for annual increments of emissions reductions needed to attain
the PM10 NAAQS by 2018. Because the West Pinal County
[[Page 1359]]
PM10 plan failed to achieve attainment by the attainment
date, the RFP demonstration based on the rate by which these reductions
were to occur is also necessarily deficient. This was borne out by the
monitoring data; no real rate of reduction of exceedances can be
demonstrated over the period of implementation of the Plan's control
measures, 2016-2018. Indeed, even with the early implementation of
additional controls designated by the State as contingency measures to
provide emissions reductions in the event of a failure to show RFP or
to attain, West Pinal County still exceeded the PM10
standard by a large margin as evidenced by the data in Table 5.
Regarding quantitative milestones, given the EPA's 2012 designation
of nonattainment for West Pinal County, the State should have included
quantitative milestones for mid-2016 and mid-2019 within the West Pinal
County PM10 Plan. Aside from the two glidepath depictions in
Figure 7-1, the Plan provides no further discussion of quantitative
milestones. What is presented in Figure 7-1 does not meet the criteria
that the Plan's quantitative milestones should be trackable,
quantified, and provide for an objective evaluation of RFP toward
attainment of the NAAQS, by mid-2016. The West Pinal County
PM10 Plan does not address RFP or quantitative milestones in
mid-2019.
For these reasons, we have determined that the West Pinal County
PM10 Plan fails to demonstrate RFP, consistent with
applicable CAA requirements and EPA guidance. Therefore, we propose to
disapprove the RFP demonstration and quantitative milestones for the
West Pinal County area for the 24-hour PM10 NAAQS under
sections 172(c)(2) and 189(c)(1).
F. Contingency Measures
1. Statutory and Regulatory Requirements
Under the CAA, states must include contingency measures consistent
with section 172(c)(9) in their nonattainment plan SIP submissions.
Contingency measures are additional controls or measures to be
implemented in the event the area fails to meet RFP or to attain the
NAAQS by the applicable attainment date. The SIP should contain trigger
mechanisms for the contingency measures, specify a schedule for
implementation, and indicate that the measure will be implemented
without significant further action by the state or the EPA.\68\
---------------------------------------------------------------------------
\68\ 81 FR 58066 (August 24, 2016).
---------------------------------------------------------------------------
Neither the CAA nor the EPA's implementing regulations establish a
specific level of emissions reductions that implementation of
contingency measures must achieve, but the General Preamble reiterates
the EPA's guidance recommendation that contingency measures should
generally provide for emissions reductions approximately equivalent to
one year's worth of RFP in the area.\69\ Where a failure to attain or
to meet RFP can be corrected in less than one year, the EPA may accept
a proportionally lesser amount sufficient to correct the identified
failure.\70\
---------------------------------------------------------------------------
\69\ 57 FR 13498, 13543-13544.
\70\ Id. at 13511.
---------------------------------------------------------------------------
It has been the EPA's longstanding interpretation of CAA section
172(c)(9) that states may meet the contingency measure requirement by
relying on Federal measures (e.g., Federal mobile source measures based
on the incremental turnover of the motor vehicle fleet each year) and
state or local measures already scheduled for implementation that
provide emissions reductions in excess of those needed to meet any
other nonattainment plan requirements, such as RACM/RACT, RFP, or
expeditious attainment. The key is that the Act requires that
contingency measures provide for additional emissions reductions that
are not relied on for RFP or attainment and that are not included in
the RFP or attainment demonstrations as meeting part of or all the
contingency measure requirements. The purpose of contingency measures
is to provide continued emissions reductions while a plan is being
revised to meet the missed milestone or attainment date.
In Bahr v. EPA, the Ninth Circuit Court of Appeals rejected the
EPA's interpretation of CAA section 172(c)(9) as allowing for early
implementation of contingency measures.\71\ The Ninth Circuit concluded
that contingency measures must take effect at the time the area fails
to make RFP or attain by the applicable attainment date, not
before.\72\ Consequently, within the geographic jurisdiction of the
Ninth Circuit, states cannot rely on early-implemented measures to
comply with the contingency measure requirements under CAA section
172(c)(9).\73\
---------------------------------------------------------------------------
\71\ Bahr v. EPA, 836 F.3d 1218, 1235-1237 (9th Cir. 2016).
\72\ Id. at 1235-1237.
\73\ The Bahr v. EPA decision involved a challenge to an EPA
approval of contingency measures under the general nonattainment
area plan provisions for contingency measures in CAA section
172(c)(9), but, given the similarity between the statutory language
in section 172(c)(9) and the ozone-specific contingency measure
provision in section 182(c)(9), we find that the decision affects
how both sections of the Act must be interpreted.
---------------------------------------------------------------------------
2. Summary of the State's Submission
ADEQ developed the West Pinal County PM10 Plan prior to
the Bahr v. EPA decision, and the plan relies solely upon surplus
emissions reductions from already implemented control measures during
the 2016-2018 period to demonstrate compliance with the contingency
measure requirements of CAA section 172(c)(9). The West Pinal County
PM10 Plan included the following early implemented state and
local regulations to meet the contingency measures requirement for the
PM10 standard: The portion of the AgBMP Rules for Pinal
County applicable to dairy operations (R18-2-611 and -611.03), and the
Pinal County Fugitive Dust Rule and Construction Dust Rule.\74\
Contingency Measures are also discussed in Appendix D.\75\
---------------------------------------------------------------------------
\74\ West Pinal County PM10 Plan, Chapter 6; Chapter
7, Table 7-4.
\75\ Appendix D, 45, Table D5-1.
---------------------------------------------------------------------------
3. The EPA's Review of the State's Submission
Arizona is within the geographic jurisdiction of the Ninth Circuit
Court of Appeals; therefore, after the Bahr v. EPA decision, the State
cannot rely on already-implemented control measures to comply with the
contingency measure requirement of CAA section 172(c)(9). To comply
with CAA section 172(c)(9), as interpreted in the Bahr v. EPA decision,
a state must develop, adopt and submit contingency measures to be
triggered upon a failure to meet RFP milestones or failure to attain
the NAAQS by the applicable attainment date regardless of the extent to
which already-implemented measures would achieve surplus emissions
reductions beyond those necessary to meet RFP milestones and beyond
those predicted to achieve attainment of the NAAQS. Arizona's adopted
and pre-implemented contingency measures do not comply with these
requirements for failure to make RFP and failure to meet attainment
contingency measures. Section 172(c)(9) requires contingency measures
to address potential failures to achieve RFP milestones or failure to
attain the NAAQS by the applicable attainment date. For these reasons,
we propose to disapprove the contingency measures element of the West
Pinal County PM10 Plan as failing to meet the contingency
measure requirements of CAA sections 172(c)(9).
[[Page 1360]]
G. Motor Vehicle Emissions Budgets for Transportation Conformity
1. Statutory and Regulatory Requirements
Section 176(c) of the CAA requires Federal actions in nonattainment
and maintenance areas to conform to the goals of the state's SIP to
eliminate or reduce the severity and number of violations of the NAAQS
and achieve timely attainment of the standards. Conformity to the goals
of the SIP means that such actions will not: (1) Cause or contribute to
violations of a NAAQS, (2) worsen the severity of an existing
violation, or (3) delay timely attainment of any NAAQS or any interim
milestone.
Actions involving Federal Highway Administration (FHWA) or Federal
Transit Administration (FTA) funding or approval are subject to the
EPA's transportation conformity rule, codified at 40 CFR part 93,
subpart A. Under this rule, metropolitan planning organizations (MPOs)
in nonattainment and maintenance areas coordinate with state and local
air quality and transportation agencies, the EPA, the FHWA, and the FTA
to demonstrate that an area's regional transportation plans and
transportation improvement programs conform to the applicable SIP. This
demonstration is typically done by showing that estimated emissions
from existing and planned highway and transit systems are less than or
equal to the motor vehicle emissions budgets (MVEBs or ``budgets'')
contained in all control strategy attainment plans designed to attain
the NAAQSs. Budgets are generally established for specific years and
specific pollutants or precursors. Attainment plans for PM10
nonattainment areas should identify budgets for mobile source emissions
of PM10, i.e., vehicle and fugitive dust emissions, in the
area for each RFP milestone year, as appropriate, and the attainment
year, if the plan demonstrates attainment.\76\
---------------------------------------------------------------------------
\76\ 40 CFR 93.102(b)(1).
---------------------------------------------------------------------------
For budgets to be approvable, they must meet, at a minimum, the
EPA's adequacy criteria at 40 CFR 93.118(e)(4). To meet these
requirements, the budgets must be consistent with the attainment and
RFP requirements and reflect all the motor vehicle control measures
contained in the attainment and RFP demonstrations.\77\ Budgets may
include a safety margin representing the difference between projected
emissions and the total amount of emissions estimated to satisfy any
requirements for attainment or RFP.
---------------------------------------------------------------------------
\77\ 40 CFR 93.118(e)(4)(iii), (iv) and (v). For more
information on the transportation conformity requirements and
applicable policies on MVEBs, please visit our transportation
conformity website at: https://www.epa.gov/otaq/stateresources/transconf/index.htm.
---------------------------------------------------------------------------
The EPA's process for determining adequacy of a budget consists of
three basic steps: (1) Providing public notification of a SIP
submission; (2) providing the public the opportunity to comment on the
budget during a public comment period; and (3) making a finding of
adequacy or inadequacy.\78\
---------------------------------------------------------------------------
\78\ 40 CFR 93.118(f)(2).
---------------------------------------------------------------------------
2. Summary of the State's Submission
The West Pinal County PM10 Plan includes a budget for
the 2018 attainment year. As discussed in Section III.E, we are
proposing to disapprove the RFP and quantitative milestones elements of
the Plan. No interim RFP budget was submitted for 2016. The State's
submitted 2018 conformity budget for PM10 for the West Pinal
County Area is provided in Table 6.
Table 6--2018 Motor Vehicle Emissions Budget for the West Pinal County
PM10 Nonattainment Area
[Tons per year]
------------------------------------------------------------------------
Source Emissions
------------------------------------------------------------------------
Direct On-Road Mobile Sources (exhaust, tire and brake wear) 173.7
Unpaved Road Fugitive Dust.................................. 26,433.5
Paved Road Fugitive Dust.................................... 1,211.1
Road Construction/Maintenance............................... 168.8
-----------
Total................................................... 27,987.1
------------------------------------------------------------------------
Source: West Pinal County PM10 Plan, Table 5-4.
The methodologies ADEQ used to develop the motor vehicle emissions
budget are provided in Appendix B of the West Pinal County
PM10 Plan.\79\ As discussed in section III.A. of this
proposal, ADEQ used MOVES2014 in the development of this budget; this
emissions factor model was the latest EPA approved version at the time
the West Pinal County PM10 Plan was developed. Paved road
vehicle miles traveled (VMT) estimates for estimating direct and
fugitive PM10 emissions were provided by MAG using an
interpolation methodology where 2018 VMT was estimated from 2015 and
2025 regional transportation modeling runs.\80\ ADEQ used the most
recently approved EPA provided AP-42 emissions factor equations to
develop paved and unpaved road fugitive dust emissions estimates.\81\
In addition to the line item source categories in the 2018 budget
presented in Table 6, ADEQ specified that the budget includes an 81 ton
per year safety margin.\82\
---------------------------------------------------------------------------
\79\ Appendix B, 120-137, and 166-180.
\80\ Appendix B, 120.
\81\ ADEQ used the appropriate AP-42 guidance in sections 13.2.1
and 13.2.2 to calculate fugitive dust from paved and unpaved roads.
The AP-42 emission factor equation inputs for estimating unpaved
road fugitive dust emissions can be found in Appendix B, Table 5-11.
The most recent EPA revision and approval of these AP-42 emission
factor equations occurred in 2011 and are reflected in the Plan's
estimates; 76 FR 6328 (February 4, 2011).
\82\ West Pinal County PM10 Plan, 62.
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The EPA has neither found this 2018 budget to be adequate, nor have
we acted on it in the past.
3. The EPA's Review of the State's Submission
As part of our review of the approvability of the motor vehicle
emissions budget in the West Pinal County PM10 Plan, we have
evaluated the budget using the adequacy criteria specified in the
transportation conformity rule.\83\ Reviewing the budget against the
criteria in the transportation conformity rule informs the EPA's
decision to propose our action on the budget. We have determined that
the 2018 budget submitted by Arizona for the West Pinal County area has
not met several of these criteria.
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\83\ 40 CFR 93.118(e)(4) and (5).
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First and foremost, Sec. 93.118(e)(4)(iv) requires that a budget,
when considered together with all other emissions sources, be
consistent with applicable requirements for RFP, attainment, or
maintenance (whichever is relevant to a given implementation plan
submission). In this case, the West Pinal County area budget is not
consistent with the requirements for attainment and RFP, as discussed
in Sections III.D and E of this proposal and our proposed disapproval
of these two Plan elements. Secondly, the West Pinal County budget is
presented in a tons per year format for an attainment plan intended to
meet the 24-hour PM10 NAAQS. The budget must be consistent
with the 24-hour timeframe of the attainment demonstration and
PM10 standard, and therefore should be presented in a tons
per day format. Finally, Sec. 93.118(e)(4)(iii) requires that the
budget be clearly identified and precisely quantified. Although ADEQ
describes an ``allowance or safety margin'' in the West Pinal County
PM10 Plan, the submitted budget does not clearly and
explicitly identify this safety margin in its presentations of the
budget.\84\ Also, a safety margin, as
[[Page 1361]]
defined in the Transportation Conformity rule, Sec. 93.101, must be
clearly presented and demonstrated to be outside and above the
emissions level demonstrating attainment, but below the threshold of
the applicable NAAQS.
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\84\ West Pinal County PM10 Plan, Table 5-4; Appendix
D, Table D4-4.
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We have reviewed the motor vehicle emissions budget in the West
Pinal County PM10 Plan and find that it does not meet
applicable statutory and regulatory requirements including the adequacy
criteria in 40 CFR 93.1118(e)(4) and (5). The primary deficiency is
that the submitted 2018 budget is not consistent with, or derived from,
a demonstration of attainment and RFP meeting the requirements of the
Act. As discussed earlier in sections III.D and III.E, we are proposing
herein to disapprove the Plan's attainment and RFP demonstrations.
Therefore, we are proposing to disapprove the 2018 budget in the West
Pinal County PM10 Plan. In addition, because we are
disapproving the attainment and RFP demonstrations, the 2018 budget is
not eligible for a protective finding.\85\
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\85\ 40 CFR 93.120(a)(3).
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If our proposed disapproval of the 2018 budget is finalized, upon
the effective date of our final rule, the area would be subject to a
conformity freeze under Sec. 93.120 of the Transportation Conformity
rule. No transportation project outside of the first four years of the
currently conforming transportation plan and transportation improvement
plan (TIP) or that meets the requirements of Sec. 93.104(f) during the
resulting conformity freeze may be found to conform until Arizona
submits a new PM10 control strategy/attainment plan, the EPA
finds the submitted budget adequate per Sec. 93.118 or approves the
new control strategy/attainment plan and conformity to the new control/
strategy implementation plan is determined.\86\ Furthermore, if, as a
result of our final disapproval action, the EPA imposes highway
sanctions under section 179(b)(1) of the Act two years from the
effective date of our final rule, then the conformity status of the
transportation plan and TIP will lapse on that date and no new
transportation plan, TIP, or project may be found to conform until
Arizona submits a new PM10 attainment plan, and conformity
to this attainment plan is determined.\87\
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\86\ 40 CFR 93.120(a)(2).
\87\ 40 CFR 93.120(a)(1).
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IV. Proposed Action
For the reasons discussed in this notice, under CAA section
110(k)(3), the EPA is proposing to approve and disapprove the following
portions of the West Pinal County PM10 Plan, submitted by
the State on December 21, 2015. Our proposed approval and disapproval
actions are as follows:
We propose to approve the 2008 base year emissions
inventory element for direct PM10 in the West Pinal County
PM10 Plan as meeting the requirements of CAA sections
172(c)(3) for the 1987 p.m.10 NAAQS;
We propose to disapprove the precursor demonstration in
the West Pinal County PM10 Plan because the demonstration is
inadequate to show that emissions reductions from all PM10
precursors do not contribute significantly to PM10 levels
exceeding the NAAQS, as required by CAA Section 189(e) for the 1987
p.m.10 NAAQS;
We propose to disapprove the RACM/RACT demonstration
element in the West Pinal County PM10 Plan because it does
not meet the requirements of CAA section 172(c)(1) and section
189(a)(1)(C) for the 1987 p.m.10 NAAQS; furthermore, the
deficiencies in the State's precursor analysis mean that the State
failed to establish in its RACM/RACT analysis that it was unnecessary
to regulate PM10 precursor emissions;
We propose to disapprove the modeled attainment
demonstration element for the 1987 p.m.10 NAAQS in the West
Pinal County PM10 Plan because it does not meet the
requirements of CAA section 189(a)(1)(B) and section 188(c)(1) to
demonstrate attainment of the 1987 p.m.10 NAAQS;
We propose to disapprove the RFP demonstration element in
the West Pinal County PM10 Plan because it does not meet the
requirements of CAA sections 172(c)(2) for the 1987 p.m.10
NAAQS;
We propose to disapprove the quantitative milestones
element in the West Pinal County PM10 Plan because it does
not meet the requirements of CAA section 189(c)(1) for the 1987
p.m.10 NAAQS;
We propose to disapprove the contingency measures element
of the West Pinal County PM10 Plan because it does not meet
the requirements of CAA section 172(c)(9) for the 1987
p.m.10 NAAQS; and,
We propose to disapprove the motor vehicle emissions
budget in West Pinal County PM10 Plan for the attainment
year of 2018 (see Table 6) because it is not consistent with or derived
from, approvable RFP or and attainment demonstrations for the 1987
PM10 NAAQS meeting the requirements of the Act.
The EPA is soliciting public comments on the issues discussed in
this proposed rule. We will accept comments from the public on this
proposal for the next 30 days and will consider those comments before
taking final action.
V. Statutory and Executive Order Reviews
Additional information about these statutes and Executive orders
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.
A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review
This action is not a significant regulatory action and was
therefore not submitted to the Office of Management and Budget (OMB)
for review.
B. Executive Order 13771: Reducing Regulations and Controlling
Regulatory Costs
This action is not an Executive Order 13771 regulatory action
because SIP approvals, including partial approvals, are exempted under
Executive Order 12866.
C. Paperwork Reduction Act (PRA)
This action does not impose an information collection burden under
the PRA because this action does not impose additional requirements
beyond those imposed by state law.
D. Regulatory Flexibility Act (RFA)
I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. This
action will not impose any requirements on small entities beyond those
imposed by state law.
E. Unfunded Mandates Reform Act (UMRA)
This action does not contain any unfunded mandate as described in
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect
small governments. This action does not impose additional requirements
beyond those imposed by state law. Accordingly, no additional costs to
state, local, or tribal governments, or to the private sector, will
result from this action.
F. Executive Order 13132: Federalism
This action does not have federalism implications. It will not have
substantial direct effects on the states, on the relationship between
the National Government and the states, or on the
[[Page 1362]]
distribution of power and responsibilities among the various levels of
government.
G. Executive Order 13175: Coordination With Indian Tribal Governments
This action does not have tribal implications, as specified in
Executive Order 13175, because the SIP is not approved to apply on any
Indian reservation land or in any other area where the EPA or an Indian
tribe has demonstrated that a tribe has jurisdiction, and will not
impose substantial direct costs on tribal governments or preempt tribal
law. Thus, Executive Order 13175 does not apply to this action.
H. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks
The EPA interprets Executive Order 13045 as applying only to those
regulatory actions that concern environmental health or safety risks
that the EPA has reason to believe may disproportionately affect
children, per the definition of ``covered regulatory action'' in
section 2-202 of the Executive order. This action is not subject to
Executive Order 13045 because it does not impose additional
requirements beyond those imposed by state law.
I. Executive Order 13211: Actions That Significantly Affect Energy
Supply, Distribution, or Use
This action is not subject to Executive Order 13211, because it is
not a significant regulatory action under Executive Order 12866.
J. National Technology Transfer and Advancement Act (NTTAA)
Section 12(d) of the NTTAA directs the EPA to use voluntary
consensus standards in its regulatory activities unless to do so would
be inconsistent with applicable law or otherwise impractical. The EPA
believes that this action is not subject to the requirements of section
12(d) of the NTTAA because application of those requirements would be
inconsistent with the CAA.
K. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations
The EPA lacks the discretionary authority to address environmental
justice in this rulemaking.
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Intergovernmental relations, Particulate matter, Reporting
and recordkeeping requirements.
Authority: 42 U.S.C. 7401 et seq.
Dated: December 23, 2020.
John Busterud,
Regional Administrator, Region IX.
[FR Doc. 2020-29092 Filed 1-7-21; 8:45 am]
BILLING CODE 6560-50-P
