[Federal Register Volume 84, Number 192 (Thursday, October 3, 2019)]
[Rules and Regulations]
[Pages 52766-52771]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-21206]



[[Page 52766]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2019-0068; FRL-10000-53-Region 9]


Determination of Attainment by the Attainment Date; 2006 24-Hour 
Fine Particulate Matter National Ambient Air Quality Standard; Pinal 
County, Arizona

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is taking final 
action to determine that the West Central Pinal County nonattainment 
area attained the 2006 24-hour national ambient air quality standard 
(NAAQS) for particulate matter with a diameter of 2.5 micrometers or 
smaller (PM2.5 or ``fine particulate matter'') by December 
31, 2017, the statutory attainment date for the area. This final action 
is based on the three-year average of annual 98th percentile 24-hour 
concentrations for the 2015-2017 period, using complete, quality-
assured, and certified PM2.5 monitoring data.

DATES: This rule will be effective on November 4, 2019.

ADDRESSES: The EPA has established a docket for this action under 
Docket ID No. EPA-R09-OAR-2019-0068. All documents in the docket are 
listed on the https://www.regulations.gov website. Although listed in 
the index, some information is not publicly available, e.g., 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Certain other material, such as 
copyrighted material, is not placed on the internet and will be 
publicly available only in hard copy form. Publicly available docket 
materials are available through https://www.regulations.gov, or please 
contact the person identified in the FOR FURTHER INFORMATION CONTACT 
section for additional availability information.

FOR FURTHER INFORMATION CONTACT: Jerry Wamsley, EPA Region IX, (415) 
947-4111, [email protected].

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

Table of Contents

I. Summary of the Proposed Action
II. Public Comments and EPA Responses
III. Final Action
IV. Statutory and Executive Order Reviews

I. Summary of the Proposed Action

    On April 25, 2019, the EPA proposed to determine that the West 
Central Pinal County nonattainment area attained the 2006 24-hour 
PM2.5 NAAQS by December 31, 2017, the statutory attainment 
date for the area.\1\ Our proposed action is based on the three-year 
average of annual 98th percentile 24-hour concentrations for the 2015-
2017 period, using complete, quality-assured, and certified 
PM2.5 monitoring data.
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    \1\ 84 FR 17368, (April 25, 2019).
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    For an area classified as Moderate under the Clean Air Act (CAA), 
such as the West Central Pinal County PM2.5 nonattainment 
area, section 188(c) provides that the statutory 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.'' 
Therefore, the applicable attainment date for West Central Pinal 
County, designated nonattainment in 2011 and classified as Moderate in 
2014, is attainment as expeditiously as practicable, but no later than 
December 31, 2017.\2\ Section 188(b)(2) of the CAA requires that the 
Administrator determine whether the state has attained the NAAQS in a 
nonattainment area by the applicable attainment date. Consequently, the 
EPA's proposed determination of attainment is pursuant to the Agency's 
statutory obligation, under CAA section 188(b)(2), to determine whether 
the West Central Pinal County nonattainment area has attained the 2006 
24-hour PM2.5 NAAQS by no later than December 31, 2017. 
Given this attainment date and the form of the 2006 24-hour 
PM2.5 NAAQS, the applicable 3-year data review period is 
calendar years 2015 to 2017.
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    \2\ 79 FR 31566, 31569, fn 5.
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    Under 40 CFR part 50, Sec.  50.13 and in accordance with appendix 
N, a nonattainment area meets the 2006 24-hour PM2.5 NAAQS 
when the area's design value is less than or equal to 35 micrograms per 
cubic meter ([micro]g/m\3\). As discussed in detail in Section III of 
our proposal, the determination of whether an area's air quality meets 
the 2006 24-hour PM2.5 NAAQS is generally based upon 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.\3\ Because we 
are determining attainment of the PM2.5 NAAQS as of December 
31, 2017, the applicable 3-year data review period is 2015-2017. 
Ambient air quality data must generally meet data completeness or 
substitution requirements for each year under evaluation. The data 
completeness requirements are met when at least 75 percent of the 
scheduled sampling days for each quarter have valid data.\4\ The state 
must submit data from ambient air monitors operated by state or local 
agencies in compliance with the EPA monitoring requirements to AQS. 
Monitoring agencies certify annually that these data are accurate to 
the best of their knowledge. Accordingly, the EPA relies primarily on 
data in AQS when determining the attainment status of areas.
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    \3\ AQS is the EPA's national repository of ambient air quality 
data.
    \4\ 40 CFR part 50, appendix N, section 4.2(b).
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    The PM2.5 ambient air quality monitoring data collected 
within the West Central Pinal County nonattainment area for the 2015-
2017 period must meet data completeness or substitution criteria 
according to 40 CFR part 50, appendix N. The ambient air quality 
monitoring data completeness requirements are met when quarterly data 
capture rates for all four quarters in a calendar year are at least 75 
percent.\5\ For the purposes of our proposal, we reviewed the data for 
the 2015-2017 period for completeness and determined that the 
PM2.5 data collected by Pinal County met the completeness 
criterion for all 12 quarters at PM2.5 monitoring sites in 
the West Central Pinal County nonattainment area. The 2015 Cowtown data 
were complete, and the 2016 and 2017 Hidden Valley data, the relocated 
Cowtown monitoring site, were complete.\6\
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    \5\ 40 CFR part 50, appendix N, section 4.2(b)(2).
    \6\ AQS Database, Combined Site Sample Values Report, dated 
March 28, 2019, included in our docket.
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    The EPA's proposed determination as to whether the West Central 
Pinal County area has attained the PM2.5 NAAQS pursuant to 
CAA section 188(b)(2) was based on monitored ambient air quality data. 
The validity of this determination depends in part on whether the 
monitoring network adequately measures ambient PM2.5 levels 
in the nonattainment area. Pinal County, the local agency responsible 
for collecting PM2.5 data in the nonattainment area, submits 
annual monitoring network plans to the EPA. These plans describe the 
status of the air monitoring network, including monitor siting, as 
required under 40 CFR part 58. The EPA reviews these annual network 
plans for compliance with the applicable monitoring requirements in 40 
CFR 58.10. With respect to PM2.5, we have found that the 
annual network

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plans submitted by Pinal County meet the applicable requirements under 
40 CFR part 58.\7\ Furthermore, we concluded in our ``Technical Systems 
Audit Report'' of Pinal County's ambient air quality monitoring program 
that the ambient air monitoring network currently meets or exceeds the 
requirements for the minimum number of monitoring sites designated as 
SLAMS for PM2.5 in the West Central Pinal County 
nonattainment area.\8\ Pinal County certifies annually that the data it 
submits to AQS are quality-assured and has done so for each year 
relevant to this determination of attainment, 2015-2017.\9\
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    \7\ We have included in our docket the correspondence 
transmitting our annual network reviews, e.g., correspondence dated 
October 30, 2017, from Gwen Yoshimura, Manager, Air Quality Analysis 
Office, EPA Region IX, to Michael Sundblom, Director, Pinal County 
Air Quality Control District.
    \8\ We have included in our docket the correspondence concerning 
our audit, e.g., correspondence dated September 28, 2016, from 
Elizabeth Adams, Acting Division Director, Air Division, EPA Region 
IX, to Michael Sundblom, Director, Pinal County Air Quality Control 
District.
    \9\ We have included in our docket Pinal County's annual data 
certifications for 2015, 2016 and 2017, e.g., correspondence dated 
April 30, 2018, from Josh DeZeeuw, Air Quality Manager, Pinal County 
Air Quality Control District, to Elizabeth Adams, Acting Division 
Director, Air Division, EPA Region IX. Annual data certification 
requirements can be found at 40 CFR 58.15.
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    Our proposal also discussed the EPA's review and approval of Pinal 
County's January 2016 relocation of the PM2.5 SLAMS 
monitoring site from the Cowtown location to a new location at Hidden 
Valley.\10\ Beginning in late 2013 and through 2015, Pinal County and 
the EPA engaged in a cooperative multi-year process to review 
alternative locations and relocate the Cowtown PM2.5 SLAMS 
monitoring site. Over the course of 2014 and 2015, Pinal County 
operated temporary monitors at two other potential replacement 
monitoring site locations (i.e., Hidden Valley; and White and Parker). 
This allowed Pinal County and the EPA to assess the data from each 
location and to determine if either of the proposed monitoring site 
locations met the applicable system modification requirements in 40 CFR 
58.14 for monitoring site relocation. Based on an assessment of 
PM2.5 concentrations, land use, and nearby sources, the EPA 
approved the relocation of the Cowtown PM2.5 SLAMS 
monitoring site to the new Hidden Valley location.\11\ The EPA stated 
in its Relocation Approval Letter that the data from the old and new 
monitoring site locations would be combined to form one continuous data 
record for design value calculations.\12\ Consequently, the 2015-2017 
design value is a composite data record consisting of 2015 data from 
the Cowtown monitoring site and 2016 and 2017 data from the relocated 
Cowtown site, now operating at Hidden Valley.
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    \10\ The site identification numbers are as follows: Cowtown 
(AQS ID: 04-021-3013); and, Hidden Valley (AQS ID: 04-021-3015).
    \11\ For a complete discussion of the EPA's review and approval 
of the Cowtown monitoring site relocation, refer to correspondence 
dated October 22, 2015, from Meredith Kurpius, EPA Region IX, to 
Michael Sundblom, Pinal County Air Quality Control District 
(``Relocation Approval Letter''), in the docket for this rulemaking.
    \12\ Id.
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    In summary, the EPA's evaluation of whether the West Central Pinal 
County nonattainment area has met the 2006 PM2.5 24-hour 
NAAQS is based on our review of the monitoring data, the adequacy of 
the PM2.5 monitoring network in the nonattainment area, and 
the reliability of the data collected by the network, as discussed in 
detail in our proposal for this action. The data indicate that the 24-
hour design value for the 2015-2017 period, 32 [micro]g/m\3\, was less 
than or equal to 35 [micro]g/m\3\, the 2006 PM2.5 24-hour 
NAAQS. Therefore, the EPA proposed to determine, based upon three years 
of complete, quality-assured and certified data from 2015-2017, that 
the West Central Pinal County nonattainment area attained the 2006 24-
hour PM2.5 NAAQS by the applicable outermost attainment 
date, December 31, 2017.

II. Public Comments and EPA Responses

    The public comment period on the proposed rule opened on April 25, 
2019, the date of its publication in the Federal Register, and closed 
on May 28, 2019. During this period, the EPA received one comment 
letter submitted by the Center for Biological Diversity (CBD). The 
CBD's comments are addressed below. A copy of their comment letter is 
included in the docket for this final action.
    Comment #1: The EPA did not follow Federal regulations and erred in 
determining attainment of the 24-hour PM2.5 NAAQS over the 
2015-2017 timeframe for two reasons. First, three years of annual data 
is needed at ``each eligible monitoring site'' to determine a design 
value. The Cowtown and Hidden Valley monitors constitute separate 
monitoring sites, and the EPA did not have three years of annual data 
at either site. Second, for a combined site data record, the monitoring 
sites must be collocated.\13\ Cowtown and Hidden Valley, however, are 
not collocated monitoring sites as defined by Federal regulations. 
Therefore, the EPA's calculated 2015-2017 design value was calculated 
incorrectly and is inconsistent with Federal regulations for developing 
design values from two separate monitoring sites.
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    \13\ The CBD comment letter used the term ``collated.'' We 
believe this term is incorrect given that the reference CBD cited 
was for the definition of ``collocated,'' per 40 CFR part 50, 
appendix N, 1.0(c).
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    Response #1: The EPA disagrees with the commenter's contention that 
combining the data from the two sites is not permitted under the Act 
and applicable Federal regulations. The EPA's monitoring regulations 
addressing ``[s]ystem modification'' contain a specific provision that 
allows for relocating an air quality monitoring site: ``[a] SLAMS 
monitor not eligible for removal under any of the criteria in 
paragraphs (c)(1) through (c)(5) of this section may be moved to a 
nearby location with the same scale of representation if logistical 
problems beyond the State's control make it impossible to continue 
operation at its current site.'' \14\ By referring to ``mov[ing]'' a 
monitor, as opposed to ``remov[ing]'' it,\15\ the monitoring 
regulations allow for such monitors to be treated as a single site for 
design value calculation purposes.
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    \14\ 40 CFR 58.14(c)(6).
    \15\ See id.
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    As discussed in our proposal, in 2013 logistical problems beyond 
the State's control made it impossible for Pinal County to continue 
operation of the Cowtown monitor. From late 2013 through 2015, Pinal 
County and the EPA engaged in a cooperative multi-year process to 
review and evaluate alternative locations and to relocate the Cowtown 
PM2.5 SLAMS monitoring site, ultimately to the Hidden Valley 
monitoring site. Because Pinal County moved the Cowtown monitor in 
accordance with the appropriate EPA regulations and guidance, including 
a notice and opportunity for public comment, and the EPA approved the 
site relocation, it is appropriate to combine the data from before and 
after the relocation for the purpose of calculating valid design 
values. We review this monitor relocation effort in more detail below.
    In 2013, the private landowners of the Cowtown monitoring site 
notified Pinal County that they would no longer allow the County's 
long-term use of their property for the monitoring site. In response, 
Pinal County negotiated a two-year lease extension to allow for 
continued data collection at the site while the County and the EPA 
worked to relocate the monitor appropriately

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according to Federal regulations and EPA guidance. Generally, the EPA 
interprets ``nearby location with same scale of representation'' to 
mean a nearby location that measures similar pollutant concentrations 
from similar emissions sources. In 2014, Pinal County initiated a 
special study to evaluate locations throughout the West Central Pinal 
County PM2.5 nonattainment area that would meet the EPA's 
monitor siting and relocation requirements, i.e., nearby locations with 
the same scale of representation.
    Viable long-term monitoring locations in the immediate vicinity of 
the Cowtown monitor were not available. As a result, from June 2014 to 
June 2015, Pinal County conducted parallel ambient monitoring at two 
nearby locations with a similar source mix and proximity to sources as 
the Cowtown monitor: Hidden Valley; and White and Parker. The 
monitoring at the three different sites revealed that with respect to 
the 98th percentile PM2.5 value, the key value for 24-hour 
NAAQS design value calculations, the Cowtown monitors and the Hidden 
Valley monitor tracked closely (28.5 and 29.0 [micro]g/m\3\ for the two 
Cowtown monitors, compared to 30.6 [micro]g/m\3\ for the Hidden Valley 
monitor). The other candidate location, White and Parker, did not track 
as closely (with a value of 24.9 [micro]g/m\3\), even though it was 
closer to the Cowtown monitors.\16\ The concurrent monitoring over a 
year at multiple monitoring sites demonstrates that the County was able 
to find another very similar site less than ten miles from the original 
site, thus satisfying the regulatory requirements for an air quality 
monitor relocation.
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    \16\ Moving the monitor to the nearest available site is not 
necessarily optimal, because the nearest available site may involve 
shifts in the most proximate land uses, may not be downwind from 
predominate sources, and may potentially underestimate concentration 
values. Instead, the EPA and the County had to balance proximity to 
the Cowtown site with keeping the site near a similar mix of land 
uses and local PM2.5 sources.
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    To conclude our review of this multi-year relocation effort, at 
Pinal County's request, the EPA evaluated the collected data and 
approved the relocation of the Cowtown monitoring site to the current 
Hidden Valley monitoring site location. The EPA determined that Pinal 
County met all applicable requirements of 40 CFR 58.14(c)(6) and 
specifically stated in our October 22, 2015 approval letter that ``[a]s 
this is a relocation, the data from the old and new sites will be 
combined to form one continuous data record for design value 
calculations.'' \17\ The EPA notes that Pinal County's analysis and the 
EPA's approval letter were subject to public comment as part of Pinal 
County's 2017 annual network plan submission and that the County 
received no adverse comments.\18\ Because the transition from the 
Cowtown monitor to the Hidden Valley monitor constituted a relocation 
and was subject to the EPA's approval under 40 CFR 58.14(c)(6), it was 
appropriate for the EPA to use the old and new monitoring sites in 
calculating a design value for the West Central Pinal County 
nonattainment area.\19\
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    \17\ For a complete discussion of the EPA's review and approval 
of the Cowtown monitoring site relocation, refer to correspondence 
dated October 22, 2015, from Meredith Kurpius, EPA Region IX, to 
Michael Sundblom, Pinal County Air Quality Control District 
(``Relocation Approval Letter''), in the docket for this rulemaking.
    \18\ Pinal County Air Quality Control District posted the draft 
2017 Ambient Monitoring Network Plan and 2016 Data Summary, 
containing the EPA's approval of the site relocation on the 
department's website, and made the document available in the 
District's offices for a public comment period from May 19, 2017 
through June 19, 2017.
    \19\ The fact that, as the commenter points out, the two 
locations are assigned separate AQS ID numbers is not determinative 
of whether data from the two locations are appropriate for 
combination. In the Relocation Approval Letter, the EPA stated ``As 
this is a relocation, the data from the old and new sites will be 
combined to form one continuous data record for design value 
calculations. Please note this in the AQS comment field for both the 
old and the new AQS site . . . .'' (emphasis added). Accordingly, 
the fact that the two locations were organized separately for data 
entry purposes does not mean that the data may not be combined for 
design value calculation purposes.
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    The combination of data from two monitoring sites to calculate a 
valid design value following an approved relocation has been a 
longstanding and common EPA practice. The EPA's 2017 Design Value 
Report for PM2.5 shows 18 PM2.5 monitoring sites 
nationwide for which pre- and post-relocation monitors are linked for 
design value calculation purposes.\20\ The design value reports for 
other pollutants show even more linked monitors.\21\
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    \20\ https://www.epa.gov/sites/production/files/2018-07/pm25_designvalues_20152017_final_07_24_18.xlsx.
    \21\ The 2017 Design Value Report for ozone shows 27 relocated 
sites linked for design value calculation purposes. https://www.epa.gov/sites/production/files/2018-07/ozone_designvalues_20152017_final_07_24_18.xlsx.
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    The EPA's longstanding practice of combining data from two 
monitoring sites when calculating a design value was explained in the 
recent 2015 Ozone (O3) NAAQS revision. In that rulemaking, 
the EPA specifically codified the existing convention in 40 CFR part 
50, appendix U, and explained that ``although data handling appendices 
for previous O3 standards do not explicitly mention site 
combinations, the EPA has approved over 100 site combinations since the 
promulgation of the first 8-hour O3 NAAQS in 1997''.\22\ The 
EPA explained, ``the EPA's intention in proposing this addition was 
merely to codify an existing convention, and to improve transparency by 
implementing site combinations in AQS design value calculations.'' \23\ 
The final rulemaking also noted that ``[p]ublic commenters unanimously 
supported'' the change in regulatory text and further clarified that 
``[s]ince this provision has already been used in practice under 
previous O3 standards, site combinations will be applied to 
AQS design value calculations for both the revised O3 
standards and previous O3 standards.'' \24\ The EPA's 
preamble in the proposed rule for the 2015 Ozone NAAQS revision further 
expands on the EPA's rationale concerning site combinations and states 
that ``[s]ite combinations may be approved by the Regional 
Administrator, after he or she has determined that the measured air 
quality concentrations do not differ substantially between the two 
sites.'' \25\ Although this specific rulemaking was for the 2015 ozone 
NAAQS, the EPA has used the same longstanding convention for 
PM2.5 site combinations, as described above. As with the 
ozone NAAQS design value calculations in advance of the 2015 ozone 
NAAQS final rule, the fact that the EPA has not at this point expressly 
codified this practice in regulatory provisions for PM2.5 
does not prevent the EPA from combining PM2.5 data for 
relocated monitors in line with its longstanding practice and as 
allowed under 40 CFR 58.14(c)(6).
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    \22\ 80 FR 65292, 65411 (October 26, 2015).
    \23\ Id.
    \24\ Id.
    \25\ 79 FR 75234, 75352 (December 17, 2014).
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    To summarize our response to the commenter's first point 
challenging our use of data from relocated monitors, in order to locate 
a site that constituted a ``nearby location with the same scale of 
representation'' under Sec.  58.14(c)(6), Pinal County and the EPA 
engaged in a cooperative multi-year process to review alternative 
locations and relocate the Cowtown PM2.5 SLAMS monitoring 
site due to logistical problems beyond the control of the State or the 
District. Pinal County and the EPA analyzed the data from candidate 
locations to determine if the proposed monitoring site locations met 
the applicable system modification requirements in 40 CFR 58.14 for 
monitoring site relocation. Specifically, based on an assessment of 
PM2.5 concentrations (which concurrent ambient monitoring 
demonstrated to track closely), land use, and nearby sources, the EPA 
approved the relocation of the Cowtown PM2.5

[[Page 52769]]

SLAMS monitoring site to the new Hidden Valley location. As noted in 
the EPA's Relocation Approval Letter, the data from the Cowtown and 
Hidden Valley monitoring site locations are suitable for combination to 
form one continuous data record for design value calculations. This 
approach is both authorized by the EPA's monitoring regulations, and 
consistent with the EPA's longstanding practice. Consequently, the 
2015-2017 design value the EPA used for this determination of 
attainment is consistent with Federal regulations concerning monitor 
relocations and the EPA's past policy and precedent for combining 
monitoring site data when computing a design value in such 
circumstances.
    The commenter's second argument, that ``[f]or a combined site data 
record, monitors have to be [collocated],'' is inapposite. The 
definition of ``combined site data record,'' given in 40 CFR part 50, 
appendix N, section 1.0(c) is ``the data set used for performing 
calculations in appendix N. It represents data for the primary monitors 
augmented with data from collocated monitors . . . .'' Although this 
provision makes clear that data from collocated monitors may be used to 
augment data from primary monitors, it does not prohibit the 
combination of data from a primary monitor, before and after it is 
relocated. Accordingly, the EPA does not agree that the regulation 
defining ``combined site data record'' indicates that the proposed 
determination of attainment was inappropriate.
    Comment #2: The CBD writes that the 98th percentile value for the 
2016-2018 period is above the NAAQS. The CBD suggests that this 
indicates three things: First, compared to the 2016-2018 Hidden Valley 
monitor's annual concentration, the 2015 Cowtown monitor's annual 
concentration is so low as to suggest that it is not representative of 
the Cowtown monitoring site; \26\ second, the area has a 
PM2.5 pollution problem, as evidenced by the fact that it is 
violating the NAAQS based on 2018 data; and third, over 2016-2018, the 
Hidden Valley monitoring site concentration values are trending upward.
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    \26\ The comment states that ``the Cowtown site, which had a 
98th percentile in 2015 of 22.6 . . . is not representative of the 
Cowtown site.'' The comment is unclear. The EPA infers that the 
commenter is indicating one of three things: (1) That the 22.6 
Cowtown value in 2015 is not indicative of long-term conditions at 
the Cowtown site, (2) that the Cowtown site is not representative of 
the Hidden Valley site, or (3) that the Hidden Valley site is not 
representative of the Cowtown site.
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    Response #2: In this notice, the EPA is acting pursuant to its 
statutory obligation to ``[w]ithin 6 months following the applicable 
attainment date for a PM10 [or PM2.5] 
nonattainment area . . . determine whether the area attained the 
standard by that date.'' \27\ As explained above, and in our proposal, 
the attainment date for the West Central Pinal County PM2.5 
nonattainment area is December 31, 2017.\28\ The statutory requirement 
to determine whether the area has attained ``by that date'' sets the 
timeframe for the EPA's analysis. The Act requires the EPA to determine 
whether the West Central Pinal County PM2.5 nonattainment 
area attained the standard by December 31, 2017. Accordingly, to the 
extent that CBD's comment suggests that the EPA must evaluate 
monitoring data that was collected subsequent to the applicable 
attainment date, the EPA disagrees. The EPA will continue to review 
data for 2018 and subsequent years, but these data are outside the 
scope of the present action.
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    \27\ 42 U.S.C. 7513(b)(2).
    \28\ For an area classified as Moderate under the Clean Air Act 
(CAA), such as the West Central Pinal County PM2.5 
nonattainment area, section 188(c) states that the statutory 
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.'' Therefore, the applicable attainment date for 
West Central Pinal County, designated nonattainment in 2011 and 
classified as Moderate in 2014, is December 31, 2017. 79 FR 31566, 
31569, fn 5.
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    The CBD's comment regarding whether the Cowtown site is 
``representative'' is unclear. To the extent that CBD's comment argues 
that the 2018 data from Hidden Valley site indicates that the 2015 data 
from the Cowtown site is not representative of the Cowtown site and 
ambient air quality at that site, this statement is unsubstantiated. 
The fact that the 2015 Cowtown design value is lower than the 2016, 
2017, and 2018 measurements at Hidden Valley does not mean that the 
2015 Cowtown data is not representative of the Cowtown site and ambient 
air quality at that location, as measured in 2015. The State and the 
EPA evaluated the respective monitor locations in 2015 and 2018 as part 
of the annual monitoring network review process, and both were 
consistent with applicable regulatory siting requirements.\29\ Some 
annual variation in monitor data is not particularly unusual for a 24-
hour NAAQS and does not automatically call into question the validity 
of a monitor location. Absent some indication of a technical problem 
with the Cowtown monitor, which the commenter does not suggest, the 
2015 data collected at the Cowtown site is representative of the 
ambient PM2.5 concentrations at the Cowtown site in 2015.
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    \29\ See Correspondence dated October 27, 2015, from Gretchen 
Busterud, EPA-Region IX, to Michael Sundblom, PCAQCD; and, 
correspondence dated October 30, 2018, from Gwen Yoshimura, Manager, 
Air Quality Analysis Office, EPA Region IX, to Michael Sundblom, 
Director, Pinal County Air Quality Control District.
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    To the extent that CBD's comment argues that the 2018 data and 
CBD's calculated 2016-2018 design value indicate that the Cowtown site 
is not representative of the Hidden Valley site, or vice versa, in our 
response to Comment #1, we discussed our rationale for approving the 
relocation of the Cowtown monitoring site and determining a design 
value using data from both the Cowtown and Hidden Valley monitors. The 
EPA concluded through that process, involving more than two years of 
cooperation with the District and substantial concurrent monitoring at 
the Cowtown and Hidden Valley sites, followed by a public notice and 
comment period, that the Hidden Valley site was a ``nearby location 
with the same scale of representation'' as the Cowtown site.\30\ That 
analysis demonstrated, based on almost a year of concurrent sampling, 
from June 2014 to June 2015, that the 98th percentile PM2.5 
concentration between the two sites tracked closely.\31\ Moreover, the 
EPA's relocation analysis included an investigation of the land use, 
and nearby sources surrounding the two sites, and concluded that they 
were similar.\32\ In light of the substantial concurrent monitoring 
data and additional analysis completed by the EPA, the commenter's 
suggestion that a cross-year comparison of data streams from different 
locations shows that one monitoring site is either not representative 
of the other, or not representative of ambient PM2.5 
concentrations at the time they were observed, is not persuasive. In 
general, pollution levels can exhibit annual variation, with 
particulate matter pollution in arid regions showing a strong 
dependency on variable factors such as variations in levels of local 
and/or regional anthropogenic emissions, the

[[Page 52770]]

effectiveness of existing local measures, and meteorology. Considering 
these varying factors, a simple cross-year comparison of the monitoring 
data at each location does not establish the comparability of the two 
sites and is not a useful means of determining that the different 
monitor locations are validly measuring ambient PM2.5 
concentrations accurately. Accordingly, the EPA disagrees with the 
commenter that the 2018 monitoring data, and any design value 
calculations stemming from it, indicate that the 2015 Cowtown data are 
not representative of ambient PM2.5 concentrations in 2015, 
or that the Cowtown and Hidden Valley sites are not sufficiently 
representative of each other, and the ambient PM2.5 
concentrations at these sites.
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    \30\ See 40 CFR 58.14(c)(6), Relocation Approval Letter.
    \31\ In fact, over the concurrent monitoring period, the 98th 
percentile value (the value used in design value calculations for 
the 24-hour NAAQS) for the Hidden Valley monitor was slightly higher 
than the value for the Cowtown monitor, suggesting that the change 
from the Cowtown site to the Hidden Valley site may lead to a higher 
design value for the 24-hour PM2.5 NAAQS.
    \32\ Relocation Approval Letter.
---------------------------------------------------------------------------

    The CBD's remaining comments, that the 2018 data shows that the 
West Central Pinal County nonattainment area has a pollution problem 
and that it shows an upward trend over time, address issues that are 
outside the scope of the present action. As explained above, the 
statutory timeframe for the EPA's analysis in this determination of 
attainment ends at the applicable attainment date of December 31, 2017. 
Although the EPA may consider the more recent air quality monitoring 
data after this date in future actions, it does not bear on the EPA's 
statutory obligation under 42 U.S.C. 7513(b)(2) to determine whether 
the West Central Pinal County nonattainment area has attained the 
standard ``by that date.'' \33\ Accordingly, the EPA disagrees with the 
commenter that the EPA should determine that the West Central Pinal 
County nonattainment area did not attain the 2006 24-hour 
PM2.5 NAAQS by its December 31, 2017 attainment date because 
of monitoring data from 2018.
---------------------------------------------------------------------------

    \33\ 42 U.S.C. 7513(b)(2).
---------------------------------------------------------------------------

III. Final Action

    For the reasons discussed in our proposed action and in this final 
rule, under section 188(b)(2) of the CAA, the EPA is taking final 
action to determine that the West Central Pinal County Moderate 
nonattainment area attained the 2006 24-hour PM2.5 NAAQS by 
its applicable attainment date, December 31, 2017. Our determination of 
attainment is based on complete, quality-assured and certified 
PM2.5 monitoring data for the appropriate three-year period, 
2015-2017.
    Once effective, this action satisfies the EPA's obligation pursuant 
to CAA section 188(b)(2) to determine whether this area attained the 
standards by the applicable attainment date. This determination of 
attainment does not constitute a redesignation to attainment. Rather, 
redesignations require states to meet several statutory criteria in CAA 
section 107(d)(3), including EPA approval of a state plan demonstrating 
maintenance of the air quality standards for 10 years after 
redesignation.

IV. Statutory and Executive Order Reviews

    This final action determines that West Central Pinal County has met 
the 2006 24-hour PM2.5 NAAQS as a statement of fact 
according to regulations and requirements discussed in this action and 
in the prior proposal. For that reason, this action:
     Is not a significant regulatory action subject to review 
by the Office of Management and Budget under Executive Orders 12866 (58 
FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
     Is not expected to be an Executive Order 13771 (82 FR 
9339, February 2, 2017) regulatory action because this action is not 
significant under Executive Order 12866;
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of Section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the Clean Air Act; and,
     Does not provide the EPA with the discretionary authority 
to address, as appropriate, disproportionate human health or 
environmental effects, using practicable and legally permissible 
methods, under Executive Order 12898 (59 FR 7629, February 16, 1994).
    This action does not have tribal implications as specified in 
Executive Order 13175. No tribal areas are located within the West 
Central Pinal County PM2.5 nonattainment area. The CAA and 
the Tribal Authority Rule establish the relationship of the Federal 
Government and tribes in developing plans to attain the NAAQS, and this 
rule does nothing to modify that relationship. Thus, Executive Order 
13175 (65 FR 67249, November 9, 2000) does not apply to this action.
    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report, which includes a copy of the rule, 
to each House of the Congress and to the Comptroller General of the 
United States. The EPA will submit a report containing this action and 
other required information to the U.S. Senate, the U.S. House of 
Representatives, and the Comptroller General of the United States prior 
to publication of the rule in the Federal Register. A major rule cannot 
take effect until 60 days after it is published in the Federal 
Register. This action is not a ``major rule'' as defined by 5 U.S.C. 
804(2).
    Under section 307(b)(1) of the Clean Air Act, petitions for 
judicial review of this action must be filed in the United States Court 
of Appeals for the appropriate circuit by December 2, 2019. Filing a 
petition for reconsideration by the Administrator of this final rule 
does not affect the finality of this action for the purposes of 
judicial review, does not extend the time within which a petition for 
judicial review may be filed, and shall not postpone the effectiveness 
of such rule or action. This action may not be challenged later in 
proceedings to enforce its requirements. (See section 307(b)(2).)

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Ammonia, Fine 
particulate matter, Incorporation by reference, Intergovernmental 
relations, Nitrogen dioxides, Reporting and recordkeeping requirements, 
Sulfur dioxides, Volatile organic compounds.

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

    Dated: September 17, 2019.
Deborah Jordan,
Acting Regional Administrator, Region IX.

    For the reasons stated in the preamble, title 40, chapter I of the 
Code of Federal Regulations is amended as follows:

[[Page 52771]]

PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

0
1. The authority citation for part 52 continues to read as follows:

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

Subpart D-Arizona

0
2. Section 52.131 is amended by adding paragraph (d) to read as 
follows:


Sec.  [thinsp]52.131  Control Strategy and regulations: Fine Particle 
Matter.

* * * * *
    (d) Determination of attainment. Effective November 4, 2019, the 
EPA has determined that, based on 2015 to 2017 ambient air quality 
data, the West Central Pinal County, AZ PM2.5 nonattainment 
area has attained the 2006 24-hour PM2.5 NAAQS by the 
applicable attainment date of December 31, 2017. Therefore, the EPA has 
met the requirement pursuant to CAA section 188(b)(2) to determine 
whether the area attained the standard. The EPA also has determined 
that the West Central Pinal County, AZ nonattainment area will not be 
reclassified for failure to attain by its applicable attainment date 
under section 188(b)(2).

[FR Doc. 2019-21206 Filed 10-2-19; 8:45 am]
 BILLING CODE 6560-50-P