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Federal Register / Vol. 86, No. 30 / Wednesday, February 17, 2021 / Proposed Rules
EPA has also reviewed the subsequent PM2.5 ambient air monitoring data in the Logan UT-ID area for the monitoring design value 5 periods of 20162018 and 20172019. Consistent with the requirements at 40 CFR part 50, Idaho
quality assured, quality-controlled and certified this ambient air monitoring data in the EPAs Air Quality System AQS. This air quality data demonstrates that the Logan UT-ID area continues to attain the 2006 24-hour
PM2.5 NAAQS. For the 20162018 threeyear period, the Smithfield monitor recorded a design value of 33 mg/m3.6
The areas 24-hour PM2.5 design values for the 20172019 three-year period are provided in Table 2 of this document.

TABLE 2LOGAN UT-ID CURRENT PM2.5 DESIGN VALUES 7
98th percentile value g/m3
Monitor
Design value 3-year average
AQS site ID
2017

Smithfield, UT
Preston, ID

490050007
160410002

2018
36.0

2019
27.9
27.2

a 17.3

35.1
30.1

33
b NA

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a The Preston monitor operated at a 1-in-3 day monitoring frequency throughout 2017 and did not begin operation until February 24, 2017, making the first quarter incomplete for this monitor with less than 50% of data reported.
b Due to the incomplete first quarter in 2017, this design value does not meet validity requirements per 40 CFR part 50, Appendix N, section 4.2ci.

As Table 2 indicates, the Logan UTID PM2.5 NAA has continued to attain the 2006 24-hour PM2.5 NAAQS since EPA issued its October 19, 2018, Determination of Attainment for the area based on the 20152017 design values shown in Table 1 of this document. We note that the Preston, ID
monitor did not produce a valid design value for the 20172019 period because the monitor did not begin operation until February 24, 2017, thus producing an incomplete first quarter for that monitoring year. Despite this, EPA finds that it is appropriate to conclude that the area has continued to attain the NAAQS since the initial 20152017
period upon which we based our October 19, 2018, Determination of Attainment, based on uninterrupted attainment at the Smithfield, UT
monitor. A review of concurrent monitoring data for the Smithfield and Preston monitors provided in Table 2 of this document, and discussed in more detail in our Technical Support Document TSD 8 included in the docket for this proposed action, shows that the Smithfield site typically records higher levels of PM2.5 than the Preston site, indicating that Smithfields location is more suitable to demonstrate maximum PM2.5 concentrations in the Cache Valley. On September 1, 2020, Utah and Idaho completed a memorandum of understanding MOU
to collectively meet the monitoring requirements of 40 CFR part 58, Appendix D in the Logan UT-ID
metropolitan statistical area MSA, allowing Idaho to rely on the Smithfield monitor in Utah as the highest concentration monitor in the MSA. As
shown, the Smithfield monitor has attained the 2006 24-hour PM2.5 NAAQS
for the 20152017, 20162018 and 20172019 design value periods. The MOU is included in the docket for this proposed action. The TSD also demonstrates that it is very unlikely that the Preston monitors first complete valid design value for the 20182020
period could exceed the 2006 PM2.5
NAAQS based on a review of all available data recorded at this monitor.
EPAs review of the monitoring data for 20162018 and 20172019 supports the previous determination that the area has attained the 2006 24-hour PM2.5
NAAQS and demonstrates that the area continues to attain the standard. As discussed further in Section III.D of this document, Idaho has committed to continue monitoring ambient PM2.5
concentrations in accordance with 40
CFR part 58. Thus, EPA is proposing to determine that the Logan UT-ID PM2.5
NAA attained the 2006 24-hour PM2.5
NAAQS.

5 As defined in 40 CFR part 50, Appendix N, section 1c.
6 See https www.epa.gov/air-trends/air-qualitydesign-valuesreport.

7 The Preston monitor does not have a valid design value for the 20172019 three-year period because of an incomplete 2017 quarter 1 which cannot be substituted with quarter 1 data at the same monitor in 2018 or 2019 per 40 CFR part 50,
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B. Applicable Requirements Under Section 110 and Part D of the CAA
Section 107d3Eii and v of the CAA states that for an area to be redesignated to attainment, it must be determined that the Administrator has fully approved the applicable implementation plan for the area under CAA section 110k and all the requirements applicable to the Area under section 110 of the CAA general SIP requirements and part D of Title I
of the CAA SIP requirements for nonattainment areas must be met.

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1. CAA Section 110 General SIP
Requirements Section 110a2 of Title I of the CAA
delineates the general requirements for a SIP, which include enforceable emissions limitations and other control measures, means or techniques, provisions for the establishment and operation of appropriate devices necessary to collect data on ambient air quality, and programs to enforce the limitations. The general SIP elements and requirements set forth in CAA
section 110a2 include, but are not limited to the following:
Submittal of a SIP that has been adopted by the state after reasonable public notice and hearing;
Provisions for establishment and operation of appropriate procedures needed to monitor ambient air quality;
Implementation of a source permit program; provisions for the implementation of Part C requirements PSD;
Provisions for the implementation of Part D requirements for NSR permit programs;
Provisions for air pollution modeling; and Provisions for public and local agency participation in planning and emission control rule development.
CAA section 110a2D requires that SIPs contain certain measures to prevent sources in a state from significantly contributing to air quality problems in another state. However, CAA section 110a2D requirements for a state are not linked with a particular nonattainment areas designation and classification in that state. EPA believes that the requirements linked with a Appendix N, section 4.2ci because it has below 50% complete data for that quarter.
8 Please see EPA R10 Ambient Monitoring TSD
in the docket for this proposed action EPAR10
OAR20200190 on www.regulations.gov.

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