[Federal Register Volume 86, Number 88 (Monday, May 10, 2021)]
[Proposed Rules]
[Pages 24829-24835]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-09215]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2021-0078; FRL-10022-86-Region 9]


Finding of Failure To Attain the 2008 Lead and 2010 Sulfur 
Dioxide Standards; Arizona; Hayden and Miami Nonattainment Areas

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
determine that the Hayden lead (Pb) nonattainment area (NAA) failed to 
attain the 2008 Pb primary and secondary national ambient air quality 
standards (NAAQS or ``standards'') by the applicable attainment date of 
October 3, 2019. This proposed determination is based upon monitored 
air quality data from November 2015-December 2018 for the 2008 Pb 
NAAQS. The EPA is also proposing to determine that the Hayden and Miami 
sulfur dioxide (SO2) NAAs failed to attain the 2010 1-hour 
SO2 primary NAAQS by the applicable attainment date of 
October 4, 2018, based upon monitored air quality data from January 
2015-December 2017. If the EPA finalizes these determinations as 
proposed, the State of Arizona will be required to submit revisions to 
the Arizona State Implementation Plan (SIP) that, among other elements, 
provide for expeditious attainment of the 2008 Pb and 2010 
SO2 standards.

DATES: Any comments must arrive by June 9, 2021.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2021-0078 at http://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 
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, 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: Ben Leers, Air Planning Office (AIR-
2), EPA Region IX, (415) 947-4279, Leers.Benjamin@epa.gov.

SUPPLEMENTARY INFORMATION: Throughout this document, ``we,'' ``us,'' 
and ``our'' refer to the EPA.

Table of Contents

I. Background
    A. The 2008 Pb and 2010 SO2 National Ambient Air 
Quality Standards
    B. Designations, Classifications, and Attainment Dates for the 
2008 Pb and 2010 SO2 National Ambient Air Quality 
Standards
II. Proposed Determinations and Consequences
    A. Applicable Statutory and Regulatory Provisions
    B. Monitoring Network Considerations
    C. Data Considerations and Proposed Determination
    D. Consequences for Pb and SO2 Nonattainment Areas 
Failing To Attain Standards by Attainment Dates
III. Proposed Action and Request for Public Comment
IV. Statutory and Executive Order Reviews

I. Background

A. The 2008 Pb and 2010 SO2 National Ambient Air Quality Standards

    Under section 109 of the Clean Air Act (CAA or ``Act''), the EPA 
has established primary and secondary NAAQS for certain pervasive air 
pollutants (referred to as ``criteria pollutants'') and conducts 
periodic reviews of the NAAQS to determine whether they should be 
revised or whether new NAAQS should be established. The primary NAAQS 
represent ambient air quality standards the attainment and maintenance 
of which the EPA has determined, including a margin of safety, are 
requisite to protect the public health.

[[Page 24830]]

The secondary NAAQS represent ambient air quality standards the 
attainment and maintenance of which the EPA has determined are 
requisite to protect the public welfare from any known or anticipated 
adverse effects associated with the presence of such air pollutant in 
the ambient air.
1. The 2008 Pb Standard
    Under the CAA, the EPA must establish NAAQS for criteria 
pollutants, including Pb. Pb is generally emitted in the form of 
particles that are deposited in water, soil, and dust. People may be 
exposed to Pb by inhaling it or by ingesting Pb-contaminated food, 
water, soil, or dust. Once in the body, Pb is quickly absorbed into the 
bloodstream and can result in a broad range of adverse health effects 
including damage to the central nervous system, cardiovascular 
function, kidneys, immune system, and red blood cells. Children are 
particularly vulnerable to Pb exposure, in part because they are more 
likely to ingest Pb and in part because their still-developing bodies 
are more sensitive to the effects of Pb. The harmful effects to 
children's developing nervous systems (including their brains) arising 
from Pb exposure may include intelligence quotient (IQ) \1\ loss, poor 
academic achievement, long-term learning disabilities, and an increased 
risk of delinquent behavior.
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    \1\ IQ is a score created by dividing a person's mental age 
score, obtained by administering an intelligence test, by the 
person's chronological age, both expressed in terms of years and 
months. ``Glossary of Important Assessment and Measurement Terms,'' 
Philadelphia, PA: National Council on Measurement in Education. 
2016.
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    The EPA first established primary and secondary Pb standards in 
1978 at 1.5 micrograms per cubic meter ([micro]g/m\3\) as a quarterly 
average.\2\ Based on new health and scientific data, on October 15, 
2008, the EPA revised the federal Pb standards to 0.15 [micro]g/m\3\ 
and revised the averaging time for the standards.\3\ Since the primary 
and secondary Pb standards are the same, we refer to them hereafter in 
this document using the singular Pb standard or NAAQS. A violation of 
the 2008 Pb NAAQS occurs if any arithmetic 3-month mean concentration 
is greater than 0.15 [micro]g/m\3\.\4\
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    \2\ 43 FR 46246 (October 5, 1978).
    \3\ 73 FR 66964 (November 12, 2008).
    \4\ 40 CFR 50.16.
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2. The 2010 SO2 Standard
    Under the CAA, the EPA must also establish a NAAQS for 
SO2. SO2 is primarily released to the atmosphere 
through the burning of fossil fuels by power plants and other 
industrial facilities. SO2 is also emitted from industrial 
processes including metal extraction from ore and heavy equipment that 
burn fuel with a high sulfur content. Short-term exposure to 
SO2 can damage the human respiratory system and increase 
breathing difficulties. Small children and people with respiratory 
conditions, such as asthma, are more sensitive to the effects of 
SO2. Sulfur oxides at high concentrations can also react 
with compounds to form small particulates that can penetrate deeply 
into the lungs and cause health problems.
    The EPA first established primary SO2 standards in 1971 
at 0.14 parts per million (ppm) over a 24-hour averaging period and 0.3 
ppm over an annual averaging period.\5\ In June 2010, the EPA revised 
the NAAQS for SO2 to provide increased protection of public 
health, providing for revocation of the 1971 primary annual and 24-hour 
SO2 standards for most areas of the country following area 
designations under the new NAAQS.\6\ The 2010 NAAQS is 75 parts per 
billion (ppb) (equivalent to 0.075 ppm) over a 1-hour averaging 
period.\7\ A violation of the 2010 1-hour SO2 NAAQS occurs 
when the annual 99th percentile of ambient daily maximum 1-hour average 
SO2 concentrations, averaged over a 3-year period, exceeds 
75 ppb.\8\
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    \5\ 36 FR 8186 (April 30, 1971).
    \6\ 40 CFR 50.4(e).
    \7\ 75 FR 35520 (June 22, 2010).
    \8\ 40 CFR 50.17.
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B. Designations, Classifications, and Attainment Dates for the 2008 Pb 
and 2010 SO2 National Ambient Air Quality Standards

    Following promulgation of any new or revised NAAQS, the EPA is 
required by CAA section 107(d) to designate areas throughout the nation 
as attaining or not attaining the NAAQS.
1. Hayden 2008 Pb Nonattainment Area
    The initial designations for the 2008 Pb NAAQS were established in 
two rounds and were completed on November 22, 2010, and November 22, 
2011.\9\ The EPA initially designated the Hayden, Arizona area as 
unclassifiable due to insufficient monitoring data.\10\ In June 2013, 
the EPA determined that quality assured, certified monitoring data 
collected in 2012 at the Arizona Department of Environmental Quality 
(ADEQ or ``State'') Globe Highway monitor showed that the area was 
violating the Pb NAAQS. Accordingly, on May 2, 2014, the EPA proposed 
to redesignate the Hayden area to nonattainment for the 2008 Pb NAAQS, 
and on September 3, 2014, finalized the nonattainment designation, 
effective October 3, 2014.\11\ Under CAA sections 172(a)(2) and 192(a), 
the attainment date for a Pb nonattainment area is the date by which 
attainment can be achieved as expeditiously as practicable, but no 
later than five years after the area is designated nonattainment. 
Therefore, the maximum attainment date for the Hayden Pb NAA is October 
3, 2019.\12\ The Hayden nonattainment area for the 2008 Pb NAAQS 
includes parts of Gila and Pinal counties.\13\
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    \9\ See 75 FR 71033 (November 22, 2010); 76 FR 72097 (November 
22, 2011).
    \10\ Arizona Department of Environmental Quality's Globe Highway 
monitor registered four violations of the Pb NAAQS in 2011; however, 
at the time of designation the data had not been quality assured and 
certified. Consequently, the EPA could not rely on those violations 
as a basis for a nonattainment designation.
    \11\ 79 FR 52205 (September 3, 2014).
    \12\ ADEQ's ``SIP Revision: Hayden Lead Nonattainment 
Area''(adopted on March 3, 2017), 18, describes ``October 2019'' as 
the attainment date for the area. Accordingly, in approving this SIP 
revision, 83 FR 56734 (November 14, 2018), the EPA established 
October 3, 2019 as the applicable attainment date for this area.
    \13\ For an exact description of the Hayden Pb NAA, refer to 40 
CFR 81.303.
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2. Hayden and Miami 2010 SO2 Nonattainment Areas
    On August 5, 2013, the EPA finalized its first round of 
designations for the 2010 primary SO2 NAAQS.\14\ In the 2013 
action, the EPA designated 29 areas in 16 states as nonattainment for 
the 2010 SO2 NAAQS, including the Hayden and Miami areas in 
Arizona. The Hayden SO2 NAA includes parts of Gila and Pinal 
counties and excludes the parts of Indian country located in the area. 
The Miami SO2 NAA includes parts of Gila County and excludes 
parts of Indian country within the area.\15\ The EPA's initial round of 
designations for the 2010 SO2 NAAQS including the Hayden and 
Miami SO2 NAAs became effective on October 4, 2013. Pursuant 
to CAA sections 172(a)(2) and 192(a), the maximum attainment date for 
the Hayden and Miami SO2 NAAs is October 4, 2018, five years 
after the effective date of the final action designating each area as 
nonattainment for the 2010 SO2 NAAQS.
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    \14\ 78 FR 47191 (August 5, 2013).
    \15\ For exact descriptions of the Hayden and Miami 
SO2 NAAs, refer to 40 CFR 81.303.
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II. Proposed Determination and Consequences

A. Applicable Statutory and Regulatory Provisions

    Section 179(c)(1) of the CAA requires the EPA to determine whether 
a nonattainment area attained an applicable standard by the applicable

[[Page 24831]]

attainment date based on the area's air quality as of the attainment 
date.
    A determination of whether an area's air quality meets applicable 
standards is generally based upon the most recent three years of 
complete, quality-assured data gathered at established state and local 
air monitoring stations (SLAMS) in a nonattainment area and entered 
into the EPA's Air Quality System (AQS) database.\16\ Data from ambient 
air monitors operated by state and local agencies in compliance with 
the EPA monitoring requirements must be submitted to AQS.\17\ 
Monitoring agencies annually certify that these data are accurate to 
the best of their knowledge.\18\ All data are reviewed to determine the 
area's air quality status in accordance with 40 CFR part 50, Appendix R 
(for Pb) and Appendix T (for SO2).
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    \16\ AQS is the EPA's repository of ambient air quality data.
    \17\ 40 CFR 58.16.
    \18\ 40 CFR 58.15.
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    We note that when determining the attainment status of 
SO2 nonattainment areas, in addition to ambient monitoring 
data, the EPA may also consider air quality dispersion modeling and/or 
a demonstration that the control strategy in the SIP has been fully 
implemented.\19\ With regard to the use of monitoring data for such 
determinations, the EPA's 2014 SO2 Guidance specifically 
notes that ``[i]f the EPA determines that the air quality monitors 
located in the affected area are located in the area of maximum 
concentration, the EPA may be able to use the data from these monitors 
to make the determination of attainment without the use of air quality 
modeling data.'' \20\ This language might be read to suggest that the 
EPA must always assess whether the air quality monitors in the affected 
area are located in the area of maximum concentration prior to using 
monitoring data to determine an SO2 NAA's attainment status. 
However, this language was intended to refer to a situation where the 
EPA is considering making a determination that the area has attained 
the NAAQS based on a finding that all of the monitoring sites within 
the affected area had an attaining design value for the relevant 
period. As described in section II.C of this notice, in this instance, 
the monitoring sites in the Hayden and Miami SO2 NAAs did 
not have attaining design values for the relevant period. Consequently, 
even if the monitoring sites are not located in the area of maximum 
concentration, any monitors that would be located in the area of 
maximum concentration could not record concentrations lower than those 
recorded at the existing monitors at the Hayden and Miami sites. 
Accordingly, since the Hayden and Miami monitors are violating the 
NAAQS, it is not necessary to consider whether the monitors are located 
in the area of maximum concentration in order to determine that the 
Hayden and Miami SO2 NAAs did not attain the 2010 
SO2 NAAQS by the October 4, 2018 attainment date. However, 
in any future assessment of whether these areas have attained the 
NAAQS, the EPA may assess whether the monitors are located in the area 
of maximum concentration and may also consider modeling and/or control 
implementation information, as appropriate.
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    \19\ EPA, Guidance for 1-Hour SO2 Nonattainment Area 
SIP Submissions (April 2014) (``2014 SO2 Guidance''), 49.
    \20\ Id., 50.
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1. Interpretation of the 2008 Pb Standard
    Under EPA regulations in 40 CFR 50.16 and in accordance with 40 CFR 
part 50 Appendix R, the 2008 Pb standard is met when the design value 
is less than or equal to 0.15 [micro]g/m\3\ at each eligible monitoring 
site within the area. The Pb design value at each eligible monitoring 
site is the maximum valid 3-month arithmetic mean Pb concentration 
calculated over three years. The 3-month mean Pb concentrations are 
rounded to the nearest hundredth [micro]g/m\3\ for comparison to the 
NAAQS. Data completeness requirements for a given 3-month period are 
met if the average of the data capture rate of the three constituent 
monthly means is greater than or equal to 75 percent.\21\
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    \21\ See 40 CFR part 50, Appendix R sections (1)c, 4(c), and 
5(b).
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2. Interpretation of the 2010 SO2 Standard
    Under EPA regulations in 40 CFR 50.17 and in accordance with 40 CFR 
part 50 Appendix T, the 2010 1-hour annual SO2 standard is 
met when the design value is less than or equal to 75 ppb. Design 
values are calculated by computing the three-year average of the annual 
99th percentile daily maximum 1-hour average concentrations.\22\ When 
calculating 1-hour primary standard design values, the calculated 
design values are rounded to the nearest whole number or 1 ppb by 
convention. An SO2 1-hour primary standard design value is 
valid if it encompasses three consecutive calendar years of complete 
data. A year is considered complete when all four quarters are 
complete, and a quarter is complete when at least 75 percent of the 
sampling days are complete. A sampling day is considered complete if 75 
percent of the hourly concentration values are reported; this includes 
data affected by exceptional events that have been approved for 
exclusion by the Administrator.\23\
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    \22\ As defined in 40 CFR part 50, Appendix T section 1(c), 
daily maximum 1-hour values refer to the maximum 1-hour 
SO2 concentration values measured from midnight to 
midnight that are used in the NAAQS computations.
    \23\ See 40 CFR part 50, Appendix T sections 1(c), 3(b), 4(c), 
and 5(a).
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B. Monitoring Network Considerations

    Section 110(a)(2)(B)(i) of the CAA requires states to establish and 
operate air monitoring networks to compile data on ambient air quality 
for all criteria pollutants. The EPA's monitoring requirements are 
specified by regulation in 40 CFR part 58. These requirements are 
applicable to state, and where delegated, local air monitoring agencies 
that operate criteria pollutant monitors. The regulations in 40 CFR 
part 58 establish specific requirements for operating air quality 
surveillance networks to measure ambient concentrations of Pb, 
including requirements for measurement methods, network design, quality 
assurance procedures, and in the case of large urban areas, the minimum 
number of monitoring sites designated as SLAMS.
    In sections 4.4 and 4.5 of Appendix D to 40 CFR part 58, the EPA 
specifies minimum monitoring requirements for Pb and SO2, 
respectively, to operate at SLAMS. SLAMS produce data that are eligible 
for comparison with the NAAQS, and therefore, the monitor must be an 
approved federal reference method (FRM), federal equivalent method 
(FEM), or approved regional method (ARM) monitor.
    The minimum number of required Pb SLAMS is described in section 4.5 
of Appendix D to 40 CFR part 58. There must be at least one source-
oriented SLAMS site located to measure the maximum Pb concentration in 
ambient air resulting from each non-airport Pb source that emits 0.50 
or more tons per year (tpy) and from each airport that emits 1.0 tpy or 
more based on either the most recent National Emission Inventory (NEI) 
or other scientifically justifiable methods and data. According to the 
2017 NEI, two non-airport sources in Gila County, Arizona exceeded the 
0.50 tpy threshold and therefore required source-oriented Pb 
monitoring: The Asarco LLC Hayden Smelter and the Freeport-McMoRan 
Miami Smelter.\24\
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    \24\ Arizona facility-level Pb emissions data from the 2017 NEI 
may be accessed on the EPA NEI website at https://www.epa.gov/air-emissions-inventories/2017-national-emissions-inventory-nei-data and 
are included in our docket via an Excel spreadsheet.

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[[Page 24832]]

    The minimum number of required SO2 SLAMS is described in 
sections 4.4.2 and 4.4.3 of Appendix D to 40 CFR part 58. According to 
section 4.4.2, the minimum number of required SO2 monitoring 
sites is determined by the population weighted emissions index for each 
state's core based statistical area. Section 4.4.3 describes additional 
monitors that may be required by an EPA regional administrator.
    Under 40 CFR 58.10, states are required to submit annual network 
plans (ANP) for ambient air monitoring networks for approval by the 
EPA. Within the Hayden Pb, Hayden SO2, and Miami 
SO2 NAAs, ADEQ is responsible for assuring that each area 
meets air quality monitoring requirements. ADEQ submits annual 
monitoring network plans to the EPA that describe the various 
monitoring sites operated by ADEQ.\25\ Each ANP discusses the status of 
the air monitoring network as required under 40 CFR 58.10 and addresses 
the operation and maintenance of the air monitoring network in the 
previous year. The EPA regularly reviews these ANPs for compliance with 
the applicable reporting requirements in 40 CFR part 58.\26\
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    \25\ See, e.g., ``State of Arizona Air Monitoring Network Plan 
for the Year 2019.'' Copies of Arizona's ANPs for 2016-2019 are 
included in the docket.
    \26\ See, e.g., letter dated November 8, 2019, from Gwen 
Yoshimura, Manager, EPA Region IX, Air Quality Analysis Office, to 
Daniel Czecholinksi, Acting Director, Air Quality Division, ADEQ. 
Copies of EPA letters responding to Arizona's ANPs for 2016-2019 are 
included in the docket.
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    The EPA also conducts regular ``technical systems audits'' (TSAs) 
during which we review and inspect ambient air monitoring programs to 
assess compliance with applicable regulations concerning the 
collection, analysis, validation, and reporting of ambient air quality 
data.\27\ In our 2018 TSA of ADEQ, we concluded that ADEQ's ambient air 
monitoring network meets or exceeds the requirements for the minimum 
number of SLAMS for all criteria pollutants, including for Pb in the 
Hayden NAA and for SO2 in the Hayden and Miami NAAs.\28\
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    \27\ See 40 CFR part 58, appendix A, section 2.5.
    \28\ See letter dated April 25, 2019, from Elizabeth Adams, 
Director, Air Division, EPA Region IX, to Timothy Franquist, 
Director, Air Quality Division, ADEQ.
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1. Hayden Pb Monitoring Network
    ADEQ operated two Pb SLAMS during the November 2015-December 2018 
data period within the Hayden Pb NAA: Globe Highway (AQS ID 04-007-
1002) and Hillcrest (AQS ID 04-025-8104). The Globe Highway site is 
located along State Route 77 in Winkelman. The Hillcrest site, which 
began monitoring on January 1, 2016, is located at 123 S. Hillcrest 
Avenue in Hayden.\29\ The primary and secondary monitors at each Pb 
monitoring site are FEM monitors.
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    \29\ Refer to Appendices C and D of the ``State of Arizona Air 
Monitoring Network Plan For the Year 2019'' (July 2019) for detailed 
descriptions and locations of each Pb monitor.
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    Based on our review of ADEQ's ANPs for the years 2016-2019 \30\ and 
the 2018 TSA of ADEQ's monitoring program, we propose to find that the 
monitoring network in the Hayden Pb NAA is adequate for the purpose of 
collecting ambient Pb concentration data for use in determining whether 
the Hayden Pb NAA attained the 2008 Pb NAAQS by the October 3, 2019 
attainment date.
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    \30\ ADEQ's ANPs for 2016-2019 address the operation and 
maintenance of their air monitoring network for 2015-2018.
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2. Hayden SO2 and Miami SO2 Monitoring Networks
    During the 2015-2017 data period, ADEQ operated one SO2 
SLAMS in the Hayden SO2 NAA: Hayden Old Jail (AQS ID 04-007-
1001); and three SO2 SLAMS in the Miami SO2 NAA: 
Miami Ridgeline (AQS ID 04-007-0009); Miami Jones Ranch (AQS ID 04-007-
0011); and Miami Townsite (AQS ID 04-007-0012). The Hayden Old Jail 
site is located on Canyon Drive and Kennecott Avenue in Hayden. The 
three SO2 SLAMS in the Miami SO2 NAA are located 
in Miami. The Miami Ridgeline site is located on 4030 Linden Street; 
\31\ the Miami Jones Ranch site is located on Cherry Flats Road; and 
the Miami Townsite site is located on Sullivan Street and Davis Canyon 
Road. The primary monitors at each of these sites are FEM monitors.\21\
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    \31\ The Miami Ridgeline site was closed on September 6, 2017, 
with EPA approval. Letter dated September 19, 2017, from Elizabeth 
Adams, Acting Director, Air Division, EPA Region IX, to Timothy S. 
Franquist, Director, Air Quality Division, ADEQ.
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    Based on our review of ADEQ's ANPs for the years 2016-2018 \32\ and 
the 2018 TSA of ADEQ's monitoring program, we propose to find that the 
monitoring networks in the Hayden SO2 and Miami 
SO2 NAAs are adequate for the purpose of collecting ambient 
SO2 concentration data for use in determining whether each 
nonattainment area attained the 2010 SO2 NAAQS by the 
October 4, 2018 attainment date.
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    \32\ ADEQ's ANPs for 2016-2018 address the operation and 
maintenance of their air monitoring network for 2015-2017.
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C. Data Considerations and Proposed Determination

    Under 40 CFR 58.15, monitoring agencies must certify, on an annual 
basis, data collected at all SLAMS and at all FRM, FEM, and ARM special 
purpose monitor stations that meet EPA quality assurance requirements. 
In doing so, monitoring agencies must certify that the previous year of 
ambient concentration and quality assurance data are completely 
submitted to AQS and that the ambient concentration data are accurate 
to the best of their knowledge. ADEQ annually certifies that the data 
it submits to AQS are quality assured, including data collected by ADEQ 
at monitoring sites in the Hayden Pb NAA, Hayden SO2 NAA, 
and Miami SO2 NAA.\33\
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    \33\ See, e.g., letter from Timothy S. Franquist, Director, Air 
Quality Division ADEQ, to Gwen Yoshimura, Manager, Air Quality 
Analysis Office, EPA Region IX, certifying calendar year 2018 
ambient air quality data and quality assurance data, dated May 1, 
2019. Copies of annual certification letters from 2016-2019 are 
included in the docket.
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1. Pb Data Considerations
    As noted in Section II.A of this notice, CAA section 179(c)(1) 
requires the EPA to determine whether a nonattainment area attained an 
applicable standard by the applicable attainment date, based on the 
area's air quality ``as of the attainment date.'' For the Hayden Pb 
NAA, for reasons discussed in Section I.B.1 of this notice, the 
applicable attainment date is October 3, 2019, with respect to the 2008 
Pb NAAQS. In accordance with Appendix R to 40 CFR part 50, compliance 
with the Pb NAAQS is determined based on data from 36 consecutive valid 
3-month periods (i.e., 38 months, or a 3-year calendar period and the 
preceding November and December). Considering the applicable attainment 
date of October 3, 2019, for the 2008 Pb NAAQS, we must review the data 
collected in the Hayden Pb NAA from November 1, 2015-December 31, 2018. 
The Pb data collected in the Hayden Pb NAA from November 1, 2015-
December 31, 2018 have been certified by ADEQ.\34\
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    \34\ Id.
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    We have also evaluated the completeness of these data in accordance 
with the requirements of 40 CFR part 50 Appendix R. As detailed in 40 
CFR part 50 Appendix R section 4(c)(i), a 3-month mean Pb value is 
determined to be valid (i.e., meets data completeness requirements) if 
the average of the data capture rate of the three constituent monthly 
means is greater than or equal to 75 percent. The data collected by 
ADEQ at the Globe Highway monitoring site meet this

[[Page 24833]]

completeness criterion for each 3-month period from November 2015-
December 2018. The Hillcrest monitoring site began collecting data on 
January 1, 2016. Three full months of data are therefore not available 
for the 3-month periods from November 2015-January 2016 and December 
2015-February 2016. The data collected by ADEQ at the Hillcrest 
monitoring site meet the Pb completeness criterion for each of the 34 
available 3-month periods from January 2016-December 2018.\35\
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    \35\ See footnote a to Table 1 of this document for a discussion 
of how we considered the data in these periods after initiation of 
the Hillcrest monitoring site.
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2. Pb Data
    The Pb design values at both SLAMS within the Hayden Pb NAA for the 
relevant 36 consecutive 3-month periods beginning November 2015 through 
December 2018 are presented in Table 1 of this notice. Table 1 
demonstrates that the Pb design values for the November 2015-December 
2018 data period are greater than 0.15 [micro]g/m\3\ at the Globe 
Highway and Hillcrest monitoring sites.

                    Table 1--2016-2018 Pb Design Values for the Hayden Pb Nonattainment Area
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                                                          Highest 3-month rolling average            Pb design
                                                 ------------------------------------------------      value
                  Site (AQS ID)                                                                     ([micro]g/
                                                       2016            2017            2018            m\3\)
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Globe Highway (04-007-1002).....................            0.14            0.21            0.15            0.21
Hillcrest (04-007-1003).........................        \a\ 0.31            0.28            0.23            0.31
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Notes:
\a\ Three full months of data are not available for the first two 3-month periods (i.e., November 2015-January
  2016 and December 2015-February 2016) at the Hillcrest Monitoring site. However, based on the ``above NAAQS
  level'' test described in 40 CFR part 58, Appendix R, Section 4(c)(ii)(A), the February 2016 3-month rolling
  average of 0.31 ug/m\3\ is considered valid.
Source: EPA, Design Value Report, November 3, 2020.

    The 2018 annual design value site (i.e., the site with the highest 
design value based on November 2015-December 2018 data) is the 
Hillcrest site with a Pb design value of 0.31 [micro]g/m\3\. Because 
the Hillcrest monitoring site began operation on January 1, 2016, three 
full months of monitoring data are not available for the 3-month 
periods from November 2015-January 2016 and December 2015-February 
2016. The EPA applied the ``above NAAQS level'' test described in 40 
CFR 50 Appendix R, Section 4(c)(ii)(A) to determine if the 3-month 
rolling average ending February 2016 could be considered valid. The 3-
month period passed the diagnostic test described therein. Therefore, 
the February 2016 3-month rolling average of 0.31 [micro]g/m\3\ is 
considered valid.
    For the area to attain the 2008 Pb NAAQS by October 3, 2019, the Pb 
design value reflecting data from November 2015-December 2018 at each 
eligible monitoring site must be equal to or less than 0.15 [micro]g/
m\3\. As shown in Table 1, the 2018 design values at both sites in the 
Hayden Pb NAA are greater than 0.15 [micro]g/m\3\. Therefore, based on 
quality-assured and certified data for November 2015-December 2018, we 
are proposing to determine that the Hayden Pb NAA failed to attain the 
2008 Pb standard by the October 3, 2019 attainment date.
3. SO2 Data Considerations
    For the Miami and Hayden SO2 NAAs, for reasons discussed 
in section I.B.2 of this notice, the applicable attainment date is 
October 4, 2018. In accordance with Appendix T to 40 CFR part 50, 
determinations of SO2 NAAQS compliance are based on three 
consecutive calendar years of data. To determine the air quality as of 
the attainment date in each nonattainment area, we must review the data 
collected during the three calendar years immediately preceding the 
attainment date for the Hayden and Miami SO2 NAAs, or 
January 1, 2015-December 31, 2017.
    The SO2 data for the Hayden and Miami SO2 
NAAs from January 1, 2015-December 31, 2017, have been certified by 
ADEQ. We have also evaluated the completeness of these data in 
accordance with the requirements of 40 CFR part 50, Appendix T. The 
data collected by ADEQ meet the quarterly completeness criterion for 
all 12 quarters in the three calendar years preceding the attainment 
date at the Hayden Old Jail and Miami Jones Ranch SO2 
monitoring sites. The data collected by ADEQ in the three calendar 
years preceding the attainment date meet the quarterly completeness 
criteria for only 11 out of 12 quarters at the Miami Townsite 
SO2 monitor and 10 out of 12 quarters at the Miami Ridgeline 
SO2 monitor. The Miami Townsite SO2 monitor 
collected only three quarters of complete data in 2016 because a 
portion of the data collected in the 1st quarter of 2016 (January 2016-
March 2016) was invalidated for not meeting quality assurance 
requirements. In 2017, the Miami Ridgeline monitor did not meet 
completeness criteria for the 2nd quarter (April 2017-June 2017) 
because a portion of data was not collected due to a collection error 
and machine malfunction, nor for the 4th quarter (October 2017-December 
2017) because the site shut down on September 26, 2017.\36\
---------------------------------------------------------------------------

    \36\ See the March 22, 2021 AQS Raw Data Report for 
SO2 monitors in the Hayden and Miami SO2 NAAs 
showing hourly data from the Miami Townsite and Miami Ridgeline 
monitors throughout 2016 and 2017.
---------------------------------------------------------------------------

4. SO2 Data
    The 1-hour SO2 design values at each monitoring site 
within the Hayden and Miami SO2 NAAs for the 2015-2017 
period are presented in Table 2. Table 2 demonstrates that the 1-hour 
SO2 design values for the 2015-2017 period are greater than 
75 ppb at each eligible monitoring site.

[[Page 24834]]



            Table 2--2015-2017 1-Hour Design Values for the Hayden and Miami SO2 Nonattainment Areas
----------------------------------------------------------------------------------------------------------------
                                     Annual 99th percentile daily maximum 1-hour
                                                       average                      1-hour design   Design value
          Site (AQS ID)           ------------------------------------------------   value (ppb)       valid?
                                        2015            2016            2017
----------------------------------------------------------------------------------------------------------------
Hayden Old Jail (04-007-1001)....             246             359             280             295  Yes.
Miami Ridgeline (04-007-0009)....             171             120          \a\ 99             130  No.
Miami Townsite (04-007-0012).....             231         \b\ 110             135             159  Yes.
Miami Jones Ranch (04-007-0011)..             242             150             270             221  Yes.
----------------------------------------------------------------------------------------------------------------
Notes:
\a\ The Miami Ridgeline monitor failed to meet completeness criteria for the 2nd quarter of 2017 (April 2017-
  June 2017) and for the 4th quarter of 2017 (October 2017-December 2017).
\b\ The Miami Townsite monitor had only three quarters of complete data in 2016 because a portion of the data
  collected in the 1st quarter of 2016 was invalidated for not meeting quality assurance requirements.
Source: EPA, Design Value Report, November 30, 2020.

    The data in Table 2 demonstrate that one site in the Hayden 
SO2 NAA and two sites in the Miami SO2 NAA failed 
to attain the 2010 1-hour SO2 NAAQS by the applicable 
attainment date of October 4, 2018, while a third site in the Miami 
NAA, the Ridgeline monitor, did not have a valid design value for this 
period. Though the annual 99th percentile daily maximum 1-hour average 
at the Miami Townsite monitor did not meet applicable completeness 
criteria for all three years in the 2015-2017 data period, the 3-year 
design value for Miami Townsite was deemed valid due to meeting the 
criteria in 40 CFR part 50 Appendix T, section 3(c)(i), which requires 
that ``at least 75 percent of the days in each quarter of each of three 
consecutive years have at least one reported hourly value, and the 
design value calculated according to the procedures specified in 
section 5 is above the level of the primary 1-hour standard.'' The 3-
year design value for Miami Ridgeline is not considered valid because 
the site did not meet the conditions in 40 CFR part 50 Appendix T, 
section 3(c)(i), (ii), or (iii) to allow for incomplete design values 
to be considered valid.
    The annual design value site in each NAA is the site with the 
highest design value based on 2015-2017 data. In the Hayden 
SO2 NAA, the annual design value site is the Hayden Old Jail 
site with a 1-hour SO2 design value of 295 ppb. In the Miami 
SO2 NAA, the annual design value site is the Miami Jones 
Ranch site with a 1-hour SO2 design value of 221 ppb.
    For an area to attain the 2010 SO2 NAAQS by the October 
4, 2018 attainment date, the design value based upon monitored air 
quality data from 2015-2017 at each eligible monitoring site must be 
equal to or less than 75 ppb for the 1-hour standard. Table 2 shows 
that the design values at each monitoring site in the Hayden and Miami 
SO2 NAAs exceed 75 ppb. Therefore, based on quality-assured 
and certified data for the 2015-2017 data period, we are proposing to 
determine that both the Hayden SO2 NAA and Miami 
SO2 NAA failed to attain the 2010 1-hour SO2 
standard by the October 4, 2018 attainment date.

D. Consequences for Pb and SO2 Nonattainment Areas Failing To Attain 
Standards by Attainment Dates

    The consequences for Pb and SO2 nonattainment areas for 
failing to attain the standards by the applicable attainment date are 
set forth in CAA section 179(d). Under section 179(d), a state must 
submit a SIP revision for the area meeting the requirements of CAA 
sections 110 and 172, the latter of which requires, among other 
elements, a demonstration of attainment and reasonable further progress 
and contingency measures. In addition, under CAA section 179(d)(2), the 
SIP revision must include such additional measures as the EPA may 
reasonably prescribe, including all measures that can be feasibly 
implemented in the area in light of technological achievability, costs, 
and any non-air quality and other air quality-related health and 
environmental impacts. In this case, the dominant source of Pb and 
SO2 emissions in the Hayden Pb and SO2 NAAs is 
the Asarco Hayden Smelter, and the dominant source of SO2 
emissions in the Miami SO2 NAA is the Freeport-McMoRan Miami 
Smelter. Due to the unique nature of these two facilities, which are 
the only two batch-process primary copper smelters in the country, we 
do not have adequate information to propose specific additional 
controls at this time. However, we are seeking comment on what 
additional measures could be feasibly implemented at these facilities 
in light of technological achievability, costs, and any non-air quality 
and other air quality-related health and environmental impacts. We also 
expect that information concerning such potential additional control 
measures would be collected by ADEQ as part of its development of SIP 
revisions to address the requirements that would be triggered by a 
final finding of failure to attain for these areas.
    The state is required to submit the SIP revision within one year 
after the EPA publishes a final action in the Federal Register 
determining that the nonattainment area failed to attain the applicable 
Pb or SO2 standard. We note that on November 10, 2020, the 
EPA published an action partially disapproving the 2010 SO2 
attainment plan for the Hayden nonattainment area.\37\ Although a final 
finding of failure to attain will not eliminate the state's obligation 
to address the disapproved elements of its prior plan submittal, the 
EPA anticipates that Arizona's submission of a new, approvable 
attainment plan in response to this finding would also satisfy these 
obligations.
---------------------------------------------------------------------------

    \37\ 85 FR 71547.
---------------------------------------------------------------------------

    In addition to triggering requirements for a new SIP submittal, a 
final determination that a nonattainment area failed to attain the 
NAAQS by the attainment date would trigger the implementation of 
contingency measures adopted under 172(c)(9).
    Under CAA sections 179(d)(3) and 172(a)(2), the new attainment date 
for each nonattainment area is the date by which attainment can be 
achieved as expeditiously as practicable, but no later than five years 
after the EPA publishes a final action in the Federal Register 
determining that the nonattainment area failed to attain the applicable 
Pb or SO2 standard.\38\
---------------------------------------------------------------------------

    \38\ Pursuant to CAA sections 172(a)(2)(D) and 192(a), the 
attainment date extension provision under section 172(a)(2)(A) does 
not apply to the Pb or SO2 NAAQS.

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

[[Page 24835]]

III. Proposed Action and Request for Public Comment

    Under CAA section 179(c)(1), the EPA proposes to determine that the 
Hayden Pb NAA failed to attain the 2008 Pb standard by the applicable 
attainment date of October 3, 2019. Under CAA section 179(c)(1), the 
EPA also proposes to determine that the Hayden SO2 NAA and 
the Miami SO2 NAA failed to attain the 2010 1-hour 
SO2 standard by the applicable attainment date of October 4, 
2018. If finalized as proposed, the State of Arizona would be required 
under CAA section 179(d) to submit revisions to the SIP for the Hayden 
Pb NAA, Hayden SO2 NAA, and Miami SO2 NAA. The 
required SIP revision for each area must, among other elements, 
demonstrate expeditious attainment of the standards within the time 
period prescribed by CAA section 179(d). If finalized as proposed, the 
SIP revisions required under CAA section 179(d) would be due for 
submittal to the EPA no later than one year after the publication date 
of the final action.
    The EPA is soliciting public comments on the issues discussed in 
this notice. We will accept comments from the public on this proposal 
for the next 30 days. We will consider these comments before taking 
final action.

IV. Statutory and Executive Order Reviews

    Additional information about these statutes and Executive Orders 
can be found at http://www2.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 therefore 
was not submitted to the Office of Management and Budget (OMB) for 
review.

B. Paperwork Reduction Act (PRA)

    This action does not impose an information collection burden under 
the provisions of the PRA because it does not contain any information 
collection activities.

C. 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. This 
proposed action, if finalized, would require the state to adopt and 
submit SIP revisions to satisfy CAA requirements and would not itself 
directly regulate any small entities.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain any unfunded mandate of $100 million 
or more, as described in UMRA (2 U.S.C. 1531-1538) and does not 
significantly or uniquely affect small governments. This action itself 
imposes no enforceable duty on any state, local, or tribal governments, 
or the private sector. This action proposes to determine that the 
Hayden Pb NAA and the Hayden and Miami SO2 NAAs failed to 
attain the NAAQS by the applicable attainment dates. If finalized, this 
determination would trigger existing statutory timeframes for the State 
to submit SIP revisions. Such a determination in and of itself does not 
impose any federal intergovernmental mandate.

E. 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 distribution of power 
and responsibilities among the various levels of government.

F. Executive Order 13175, Consultation and Coordination With Indian 
Tribal Governments

    This action does not have tribal implications as specified in 
Executive Order 13175. The proposed finding of failure to attain the Pb 
and SO2 NAAQS does not apply to tribal areas, and the 
proposed rule would not impose a burden on Indian reservation lands or 
other areas where the EPA or an Indian tribe has demonstrated that a 
tribe has jurisdiction within the Hayden Pb, Hayden SO2 and 
Miami SO2 nonattainment areas. Thus, this proposed rule does 
not have tribal implications and will not impose substantial direct 
costs on tribal governments or preempt tribal law as specified by 
Executive Order 13175. Nonetheless, the EPA has notified the San Carlos 
Apache Tribe of the San Carlos Reservation, which borders the eastern 
boundary of the Hayden Pb and Hayden SO2 NAAs, of the 
proposed action.

G. 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 proposed action is not 
subject to Executive Order 13045 because the effect of this proposed 
action, if finalized, would be to trigger additional planning 
requirements under the CAA. This proposed action does not establish an 
environmental standard intended to mitigate health or safety risks.

H. Executive Order 13211, Actions That Significantly Affect Energy 
Supply, Distribution, or Use

    This proposed rule is not subject to Executive Order 13211, because 
it is not a significant regulatory action under Executive Order 12866.

I. National Technology Transfer and Advancement Act (NTTAA)

    This rulemaking does not involve technical standards.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations

    The EPA believes that this action does not have disproportionately 
high and adverse human health or environmental effects on minority 
populations, low-income populations and/or indigenous peoples, as 
specified in Executive Order 12898 (59 FR 7629, February 16, 1994). The 
effect of this proposed action, if finalized, would be to trigger 
additional planning requirements under the CAA.

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Lead, Pollution, Sulfur 
dioxide.

    Dated: April 23, 2021.
Deborah Jordan,
Acting Regional Administrator, Region IX.
[FR Doc. 2021-09215 Filed 5-7-21; 8:45 am]
BILLING CODE 6560-50-P


