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Federal Register / Vol. 86, No. 114 / Wednesday, June 16, 2021 / Rules and Regulations NAAQS. We stated that our determination was based on the ADEQs interpretation of the narrow manner in which the exemption applies, the limited types of operations that are considered to be normal farm operations, and the ADEQs retention of authority to address any potentially exempt sources that may endanger attainment or maintenance of the NAAQS or enforcement of the control strategy. We agreed that the vast majority of these operations are likely already exempted from the ADEQs SIPapproved minor NSR program under the general exemption for excluding fugitive emissions in permitting applicability determinations. We concluded that the ADEQs basis and explanation for the exemption from minor NSR review for agricultural equipment used in normal farm operations was acceptable.40
The commenters question certain aspects of the ADEQs explanation and the EPAs rationale for approving the agricultural exemption as described above. First, the commenters disagree with the ADEQs explanation of the permit exemption not being applicable to sources that are subject to a standard under 40 CFR parts 60, 61, or 63 or that are title V sources. The commenters do not see how this interpretation, which they say results in a blanket exemption for minor sources from permitting, is protective of the NAAQS.
In response, this explanation simply clarifies the scope of the exemption by confirming that major sources and sources subject to a standard under 40
CFR parts 60, 61, or 63 cannot use the exemption. We disagree with the commenters that this interpretation by the ADEQ results in a blanket exemption for minor sources. Among other things, we note that sources that are subject to a standard under 40 CFR
parts 60, 61, or 63 are often minor sources. The ADEQ has clarified that if any aspect of a stationary source is subject to one of these federal standards, then the entire stationary source, including any agricultural equipment used in normal farm operations, becomes subject to the ADEQs permitting program.41
40 85

FR 83868, 83873.
commenters also state that the fact that no one has challenged R182302C does not mean a challenge could not occur in the future.
This concern appears to address the ADEQs reference to the fact that the Arizona Attorney General issued an opinion recognizing the validity of this exemption in support of the States Title V
program in 1993. See section 4.2.1 of the 2020
Minor NSR submittal at 10. As the ADEQ
explained, the EPA stated in 1996 that it would defer to this opinion of the Arizona Attorney General in the absence of a successful legal challenge to the regulation. The commenters did
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Second, the commenters take issue with the ADEQs explanation that it expects the overwhelming majority of emissions from agricultural equipment used in normal farm operations to be fugitive emissions. The commenters assert that the fact that most of these exempted emissions are expected to be fugitive does not explain how the exemption is protective of the NAAQS.
In response, it is important to understand the context for this explanation from the ADEQ. In our 2015
NSR action, as part of our limited approval and limited disapproval of the ADEQs NSR program, the EPA
approved of the ADEQ minor NSR
programs treatment of fugitive emissions in determining when a permit is required. The ADEQs minor NSR
program requires fugitive emissions to be included in permit applicability determinations for certain industrial source categories listed in R182
10123, such as Portland cement plants, primary lead smelters, primary copper smelters, and fossil-fuel-fired steam electric plants; and for sources which, as of August 7, 1980, were being regulated under section 111 or 112 of the Act. Fugitive emissions are not included in permit applicability determinations for any other minor sources; however, fugitive emissions are reviewed in minor NSR permit actions for any source triggering review because of non-fugitive emissions. See R182
10112, R182101128, and R182
302F. In our 2015 NSR action, we approved the ADEQs minor NSR
program under 40 CFR 51.160e, including its treatment of sources of fugitive emissions, with the exception of the specific limited disapproval issues that we identified and that the ADEQ is addressing in the 2020 Minor NSR
submittal. See section 5.2.2.3 of the EPAs 2015 TSD at 2627; 80 FR 67319, 67323, 67332. In its 2020 Minor NSR
submittal, the ADEQ is clarifying that the overwhelming majority of sources that could potentially use the agricultural equipment permit exemption are fugitive emissions sources that the EPA already approved for exemption from determining whether a permit is required, in our 2015 action. As a result, the agricultural equipment exemption does not create an additional large category of sources exempt from minor NSR permitting.
The commenters, however, further argue that fugitive dust emissions from agricultural equipment are primarily addressed through the States Ag BMP
program, and that experience with the not otherwise explain how this concern affects the approvability of the 2020 Minor NSR submittal.

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Ag BMP program in both Maricopa County and Pinal County has demonstrated that it is wholly inadequate to ensure compliance with the PM10 NAAQS. The commenters are concerned that the two PM10
nonattainment areas in Maricopa and Pinal counties continue to violate the NAAQS despite the adoption of the Ag BMP program. The commenters point to recent exceedances of the PM10 NAAQS
in the Phoenix planning area which covers portions of Maricopa and Pinal counties and the fact that the West Pinal nonattainment area did not attain the PM10 standard by the attainment date and was recently reclassified to serious nonattainment for PM10. While the nonattainment issues in these areas are concerning, it is important to recognize that the Maricopa County Air Quality Department and Pinal County Air Quality Control District, rather than the ADEQ, have original jurisdiction for permitting minor sources in these areas of Arizona,42 thus the ADEQs minor NSR program would generally be inapplicable in these areas. Given that the ADEQs minor NSR program does not generally extend to sources in the Phoenix and West Pinal PM10
nonattainment areas, the commenters concerns about the use of the Ag BMP
program to address fugitive dust in the Phoenix and West Pinal PM10
nonattainment areas do not indicate that the ADEQs regulation of exempt agricultural equipment used in normal farm operations in other areas that are within the ADEQs minor NSR
permitting jurisdiction is necessary for attainment and maintenance of the NAAQS.43
Third, the commenters question the ADEQs statement that in the overwhelming majority of the remaining cases, equipment used in normal farm operations will be located at a stationary source that either qualifies as a title V
source or includes equipment subject to a new source performance standard NSPS. The commenters believe that the ADEQ has not supported this claim.
The commenters are also concerned because they claim that the NSPS
standards do not apply during periods of startup, shutdown, and malfunction, while the NAAQS apply at all times. We disagree that the ADEQ did not support this claim. Section 4.2.5 of the 2020
Minor NSR submittal provides the 42 See the ADEQs July 2, 2014 supplement to the 2012 NSR SIP submittal at 89.
43 We note that the commenters general concerns about the sufficiency of the Arizona Ag BMP
program in the Phoenix and West Pinal PM10
nonattainment areas are outside the scope of this action on revisions to the ADEQs minor NSR
program.

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