Document ID: EPA-R09-OAR-2020-0109-0025
Agency: epa
Document Type: Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: Arizona; Nonattainment Plan for the Hayden Sulfur Dioxide Nonattainment Area
Posted Date: 2020-11-10T05:00Z

[Federal Register Volume 85, Number 218 (Tuesday, November 10, 2020)]
[Rules and Regulations]
[Pages 71547-71553]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-23030]

[[Page 71547]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2020-0109; FRL-10014-84-Region 9]

Partial Approval and Partial Disapproval of Air Quality 
Implementation Plans; Arizona; Nonattainment Plan for the Hayden SO2 
Nonattainment Area

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is finalizing a 
partial approval and partial disapproval of an Arizona state 
implementation plan (SIP) revision for attaining the 2010 1-hour 
primary sulfur dioxide (SO2) national ambient air quality 
standard (NAAQS or ``standard'') for the Hayden SO2 
nonattainment area (NAA). This SIP revision (hereinafter called the 
``Hayden SO2 Plan'' or ``Plan'') includes Arizona's 
attainment demonstration and other elements required under the Clean 
Air Act (CAA or ``Act''). The EPA is approving the base year and 
projected emissions inventories and affirming that the new source 
review requirements for the area have been met. We are disapproving the 
attainment demonstration, as well as other elements of the Plan tied to 
this demonstration, namely, the requirement for meeting reasonable 
further progress (RFP) toward attainment of the NAAQS, reasonably 
available control measures and reasonably available control technology 
(RACM/RACT), enforceable emissions limitations and control measures, 
and contingency measures.

DATES: This rule will be effective on December 10, 2020.

ADDRESSES: The EPA has established a docket for this action under 
Docket No. EPA-R09-OAR-2020-0109. 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. 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: Ashley Graham, EPA Region IX, Air 
Division, Air Planning Office, 75 Hawthorne St., San Francisco, CA 
94105. By phone: (415) 972-3877 or by email at graham.ashleyr@epa.gov.

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

Table of Contents

I. Background
II. Public Comments and EPA Responses
    A. Comments From ADEQ
    B. Comments From Asarco
III. The EPA's Final Action
IV. Statutory and Executive Order Reviews

I. Background

    On June 22, 2010, the EPA promulgated a new 1-hour primary 
SO2 NAAQS of 75 parts per billion (ppb) (hereinafter called 
``the 2010 SO2 NAAQS'' or ``the SO2 NAAQS''). 
This standard is met at an ambient air quality monitoring site when the 
3-year average of the annual 99th percentile of daily maximum 1-hour 
average concentrations does not exceed 75 ppb, as determined in 
accordance with appendix T of 40 CFR part 50.\1\ On August 5, 2013, the 
EPA designated 29 areas of the country as nonattainment for the 2010 
SO2 NAAQS, including the Hayden SO2 NAA within 
Arizona.\2\ These area designations became effective on October 4, 
2013. Section 191(a) of the CAA directs states to submit SIP revisions 
for areas designated as nonattainment for the SO2 NAAQS to 
the EPA within 18 months of the effective date of the designation, 
i.e., in this case by no later than April 4, 2015. Under CAA section 
192(a), these SIP submissions are required to include measures that 
will bring the NAA into attainment of the NAAQS as expeditiously as 
practicable, but no later than five years from the effective date of 
designation. The attainment date for the Hayden SO2 NAA was 
October 4, 2018.
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    \1\ 75 FR 35520 (codified at 40 CFR 50.17(a)-(b)).
    \2\ 78 FR 47191 (codified at 40 CFR part 81, subpart C).
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    Nonattainment plans for SO2 must meet sections 110, 172, 
191, and 192 of the CAA. The EPA's regulations governing nonattainment 
SIP submissions are set forth at 40 CFR part 51, with specific 
procedural requirements and control strategy requirements residing at 
subparts F and G, respectively. Soon after Congress enacted the 1990 
Amendments to the CAA, the EPA issued comprehensive guidance on SIP 
revisions in the ``General Preamble for the Implementation of Title I 
of the Clean Air Act Amendments of 1990'' (``General Preamble'').\3\ 
Among other things, the General Preamble addressed SO2 SIP 
submissions and fundamental principles for SIP control strategies.\4\ 
On April 23, 2014, the EPA issued guidance for meeting the statutory 
requirements in SO2 SIP submissions in a document titled, 
``Guidance for 1-Hour SO2 Nonattainment Area SIP 
Submissions'' (``2014 SO2 Guidance'').\5\ In the 2014 
SO2 Guidance, the EPA described the statutory requirements 
for a complete nonattainment plan, which include: An accurate emissions 
inventory of current emissions for all sources of SO2 within 
the NAA; an attainment demonstration; a demonstration of RFP; 
implementation of RACM (including RACT); new source review; enforceable 
emissions limitations and control measures; conformity; and adequate 
contingency measures for the affected area.
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    \3\ 57 FR 13498 (April 16, 1992).
    \4\ Id. at 13545-13549, 13567-13568.
    \5\ EPA, Guidance for 1-Hour SO2 Nonattainment Area 
SIP Submissions, April 23, 2014, available at https://www.epa.gov/sites/production/files/2016-06/documents/20140423guidance_nonattainment_sip.pdf.
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    For the EPA to fully approve a SIP revision as meeting the 
requirements of CAA sections 110, 172, 191, and 192, and the EPA's 
regulations at 40 CFR part 51, the plan for the affected area needs to 
demonstrate that each of the aforementioned requirements has been met. 
Under CAA section 110(l), the EPA may not approve a plan that would 
interfere with any applicable requirement concerning NAAQS attainment 
and RFP, or any other applicable requirement. Under CAA section 193, no 
requirement in effect (or required to be adopted by an order, 
settlement, agreement, or plan in effect before November 15, 1990) in 
any area that is a NAA for any air pollutant may be modified in any 
manner unless it ensures equivalent or greater emission reductions of 
such air pollutant.
    The EPA published a notice on March 18, 2016, finding that Arizona 
and other states had failed to submit the required SO2 
nonattainment plans for the Hayden SO2 NAA and several other 
areas by the submittal deadline.\6\ This finding, which became 
effective on April 18, 2016, initiated a deadline under CAA section 
179(a) for the potential imposition of new source review offset and 
highway funding sanctions. Additionally, under CAA section 110(c),

[[Page 71548]]

the finding triggered a requirement that the EPA promulgate a federal 
implementation plan within two years of the effective date of the 
finding unless the State has submitted, and the EPA has approved, the 
nonattainment plan as meeting applicable requirements.
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    \6\ 81 FR 14736 (March 18, 2016).
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    In response to the EPA's finding, the Arizona Department of 
Environmental Quality (ADEQ) submitted the Hayden SO2 Plan 
on March 9, 2017, and submitted associated final rules on April 6, 
2017.\7\ The EPA issued letters dated July 17, 2017, and September 26, 
2017, finding the submittals complete and halting the sanctions clock 
under CAA section 179(a).\8\
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    \7\ Letters dated March 8, 2017, and April 6, 2017, from Tim 
Franquist, Director, Air Quality Division, ADEQ, to Alexis Strauss, 
Acting Regional Administrator, EPA Region IX. Although the cover 
letter for the Hayden SO2 Plan was dated March 8, 2017, 
the Plan was transmitted to the EPA on March 9, 2017.
    \8\ Letters dated July 17, 2017, and September 26, 2017, from 
Elizabeth Adams, Acting Air Division Director, EPA Region IX, to Tim 
Franquist, Director, Air Quality Division, ADEQ.
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II. Public Comments and EPA Responses

    The EPA proposed to partially approve and partially disapprove the 
Hayden SO2 Plan on May 22, 2020.\9\ Our proposed action 
contains more information on the basis for this rulemaking and on our 
evaluation of the submittal. In a separate, concurrent action, we also 
proposed a limited approval and limited disapproval of Arizona 
Administrative Code, Title 18, Chapter 2, Article 13, Section R18-2-
B1302 (``Rule B1302'').\10\
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    \9\ 85 FR 31118.
    \10\ 85 FR 31113 (May 22, 2020).
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    The EPA's proposed action for the Hayden SO2 Plan 
provided a 30-day public comment period. During this period, we 
received comments from Freeport-McMoRan Incorporated (FMI) and ASARCO 
LLC (``Asarco'').11 12 We also received comments from ADEQ, 
submitted to the docket for our related proposal on Rule B1302, that 
are relevant to our proposed action on the Hayden SO2 
Plan.\13\ All comments received on both proposals, including the 
comments from ADEQ, are included in the docket for this action. The 
comments from FMI pertain to Rule B1302 and are addressed in our final 
action on the rule. Copies of these responses are also included in the 
docket for this action.\14\ The comments from ADEQ and from Asarco, 
along with our responses, are summarized below.
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    \11\ Letter dated June 22, 2020, from Todd Weaver, Senior 
Counsel, Freeport-McMoRan, to Rulemaking Docket EPA-R09-2020-0109, 
Subject: ``Re: Comments on Partial Approval and Partial Disapproval 
of Air Quality Implementation Plans; Arizona Nonattainment Plan for 
the Hayden SO2 Nonattainment Area (EPA-R09-OAR-2020-0109) 
and Limited Approval, Limited Disapproval of Arizona Plan Revisions, 
Hayden Area; Sulfur Dioxide Control Measures--Copper Smelters (EPA-
R09-OAR-2020-0173).''
    \12\ Letter dated June 22, 2020, from Amy Veek, Environmental 
Manager, Asarco Hayden Operations, ASARCO LLC, to Ashley Graham, Air 
Planning Office, Air Division, EPA Region 9, Subject: ``Re: Comments 
of ASARCO LLC on (1) ``Partial Approval and Partial Disapproval of 
Air Quality Implementation Plans; Arizona; Nonattainment Plan for 
the Hayden SO2 Nonattainment Area, 85 FR 31118 (May 22, 
2020), Docket No. EPA-R09-OAR-2020-0109. (2) ``Limited Approval, 
Limited Disapproval of Arizona Air Plan Revisions, Hayden Area; 
Sulfur Dioxide Control Measures--Copper Smelters, 85 FR 31113 (May 
22, 2020), Docket No. EPA-R09-OAR-2020-0173.''
    \13\ Letter dated June 18, 2020, from Daniel Czecholinski, Air 
Quality Division Director, ADEQ, to Rulemaking Docket EPA-HQ-OAR-
2020-0109, Subject: ``Partial Approval Partial Disapproval of Air 
Quality Implementation Plans; Arizona; Nonattainment Plan for the 
Hayden SO2 Nonattainment Area, Docket ID Number: EPA-HQ-
OAR-2020-0109.'' ADEQ's comment letter mistakenly references 
Rulemaking Docket ``EPA-HQ-OAR-2020-0109'' instead of the rulemaking 
docket for this action, ``EPA-R09-OAR-2020-0109,'' and was submitted 
to the rulemaking docket for our related proposal on Rule B1302, 
``EPA-R09-OAR-2020-0173.''
    \14\ Response to Comments Document for the EPA's Final Actions 
on the ``Arizona State Implementation Plan Revision: Hayden Sulfur 
Dioxide Nonattainment Area for the 2010 SO2 NAAQS'' and 
Rule R18-2-B1302, ``Limits on SO2 Emissions from the 
Hayden Smelter'' (September 2020).
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A. Comments From ADEQ

    Comment: ADEQ's comment letter expresses concern that the EPA's 
proposed action does not clearly acknowledge the work that ADEQ and 
Asarco have completed since identifying the modeling error that was 
part of the basis for the EPA's proposed disapproval of the modeled 
attainment demonstration and related elements. ADEQ describes the 
modeling error that was discovered in 2017 after the SIP revision was 
submitted to the EPA and discusses the extensive work that was 
conducted to develop a revised modeling methodology. These efforts 
include additional analyses, work to justify new assumptions and 
modeling parameters, and the development of new modeling files and a 
modeling technical support document (TSD), draft versions of which were 
shared with EPA staff for review. ADEQ does not dispute the modeling 
error and acknowledges that the EPA was required to take action on the 
SIP revision submitted in March 2017. However, ADEQ expresses concern 
that the language in the EPA's proposal could lead the reader to 
believe that it knowingly submitted a SIP revision containing a flawed 
attainment demonstration, that the error was a recent discovery, or 
that it has taken no action to resolve the modeling issue. ADEQ 
contends that a clarification regarding the additional modeling efforts 
would help avoid any misunderstanding. Finally, ADEQ asserts that the 
new modeling methodology shows attainment of the NAAQS and that it was 
approved by the EPA in 2018.
    Response: We agree that extensive work has been done by ADEQ and 
Asarco, in consultation with EPA staff, to correct the flawed modeling 
in the March 2017 submittal. While we noted in our proposal that ADEQ 
has been working with Asarco and the EPA on revised modeling, we 
acknowledge that the high level of effort that has gone into that work 
was not clearly presented in our proposed action and the sequence of 
ADEQ submitting the SIP revision in March 2017, identifying the error 
later in 2017, and subsequently working extensively with Asarco and the 
EPA to correct the error was not discussed.
    In response to the statement that the new methodology was approved 
by the EPA in 2018, we would like to clarify that, while ADEQ and 
Asarco consulted with EPA staff to revise the modeling, and has shared 
new modeling files and a modeling TSD with EPA staff, these documents 
have not undergone ADEQ public notice and comment or been formally 
submitted to the EPA as a SIP revision. Therefore, the revised modeling 
has not been formally approved by the EPA and was not evaluated as part 
of our proposed action. Only upon such future submission, if it occurs, 
will the EPA be able to formally evaluate and make a determination 
regarding its adequacy to demonstrate attainment of the 2010 
SO2 NAAQS.

B. Comments From Asarco

    Comment: Asarco notes that it has spent considerable time and 
resources since 2011, in collaboration with ADEQ and the EPA, to 
achieve attainment of the 2010 SO2 NAAQS in the Hayden NAA. 
The commenter states that Asarco's efforts, including improvements to 
the capture and control systems, retrofits and rebalancing of the 
converter aisle to enhance sulfur recovery at the acid plant, and 
installation of an improved preheater system to reduce startup 
emissions, have resulted in SO2 emission reductions of 
approximately 90 percent relative to pre-2010 levels.
    Response: The EPA acknowledges the efforts that Asarco has 
undertaken to reduce SO2 emissions and improve air quality 
in the Hayden SO2 NAA. A

[[Page 71549]]

summary of the equipment and process upgrades that have been 
implemented was included in our proposed action,\15\ and a more 
detailed discussion was included in the TSD accompanying our proposed 
action on Rule B1302.\16\
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    \15\ 85 FR 31118, 31122.
    \16\ EPA, ``Technical Support Document for the EPA's Rulemaking 
for the Arizona State Implementation Plan; Arizona Administrative 
Code, Title 18, Chapter 2, Article 13, Part B--Hayden, Arizona, 
Planning Area, R18-2-B1302--Limits on SO2 Emissions from 
the Hayden Smelter,'' April 2020 (``Rule B1302 TSD'').
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    Comment: Asarco asserts that the statement in the EPA's proposal 
that an error in ADEQ's modeling ``changed predicted SO2 
concentrations such that the modeling no longer shows attainment of the 
2010 SO2 NAAQS'' \17\ is disingenuous because ADEQ's revised 
modeling demonstration shows attainment of the 2010 SO2 
NAAQS. Asarco believes that the accompanying footnote \18\ in the 
proposed action suggests that the modeling error was discovered in 
2020, rather than in 2017, and suggests that the EPA should have 
acknowledged that ADEQ's revised modeling shows attainment even if the 
EPA felt compelled to act only on the submitted version of the plan.
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    \17\ 85 FR 31118, 31120.
    \18\ Id. at footnote 16.
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    Response: As discussed in our response to ADEQ's comments in 
Section II.A of this notice, the EPA does not dispute that the modeling 
error was discovered in 2017. We referenced the 2020 email \19\ in our 
proposed action because we did not have contemporaneous documentation 
of the discovery of the modeling error to cite in our proposal. We did 
not intend for our proposal to suggest that the modeling error was 
identified in 2020 and acknowledge the extensive work that has been 
done by ADEQ and Asarco to revise the modeling in the March 2017 SIP 
revision.
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    \19\ Email dated March 25, 2020, from Farah Esmaeili, ADEQ, to 
Rynda Kay, EPA Region IX.
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    We also note that ADEQ and Asarco have informally sent draft 
revised modeling to EPA staff, who have provided feedback on the draft 
revised modeling. However, as previously noted, ADEQ has not yet 
released the revised modeling for public notice and comment or formally 
submitted the modeling to the EPA as a SIP revision. Accordingly, the 
EPA has not yet reviewed the revised modeling for approvability under 
the applicable requirements of the CAA and EPA regulations.
    Comment: Asarco asserts that under CAA section 172(c)(6), ``other 
control measures, means or techniques'' may be sufficient to achieve 
and demonstrate attainment of the NAAQS, and therefore, it does not 
agree that the Hayden SO2 Plan cannot be approved without 
numeric fugitive emissions limits. Asarco contends that the EPA 
improperly relied upon selective citation of the CAA and EPA 
regulations and non-binding guidance to conclude that a numeric 
fugitive emissions limit is required. Asarco lists the ``other control 
measures, means or techniques'' provided for in the Hayden 
SO2 Plan, which it asserts are sufficient ``to achieve and 
demonstrate attainment of the 2010 SO2 NAAQS,'' including 
new and upgraded capture and control equipment, operation and 
maintenance plans for process and control equipment, numeric emissions 
limits on the main stack, a new preheater system to reduce startup 
emissions, work practice controls for fugitive emissions, and fugitive 
emissions studies to evaluate the efficacy of the improved gas capture 
and control equipment.
    Response: We disagree with this comment. Section 172(c)(6) of the 
CAA requires attainment plans to include ``enforceable emission 
limitations, and such other control measures, means or techniques'' as 
necessary or appropriate to provide for attainment. The guidance 
documents we cited in our proposal (i.e., the General Preamble and the 
2014 SO2 Guidance) describe and interpret CAA section 
172(c)(6) and other binding statutory and regulatory requirements. 
While the guidance documents are not themselves binding, they guide the 
EPA's review of SIP submittals for compliance with the relevant 
requirements. In any case, the text of section 172(c)(6) is clear that 
the EPA must determine whether a submitted SIP includes all enforceable 
emission limitations and other measures that are necessary to provide 
for attainment. While measures other than emission limits might be 
sufficient by themselves in some circumstances (for example, where a 
particular source contributes little to the attainment problem or is 
not susceptible to a numeric limit due to technological limitations), 
such circumstances do not exist in this case, given that fugitive 
SO2 emissions at the Hayden facility have the potential to 
cause or contribute to NAAQS violations and are capable of being 
continuously monitored.\20\
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    \20\ Letter dated April 29, 2019, from Elizabeth Adams, Air 
Division Director, EPA Region IX, to Timothy Franquist, Air 
Director, ADEQ, Subject: ``Re: Comments on draft letter regarding 
R18-2-B1302'' (``April 2019 Comment Letter'').
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    The measures listed in Asarco's comment, while important components 
of the control strategy, do not ensure that fugitive emissions will 
remain at the level that was assumed in the attainment modeling. In 
particular, the installation of new and improved capture and control 
equipment was expected to reduce fugitive emissions, but, in the 
absence of ongoing monitoring, it is not known whether these changes 
were sufficient to reduce emissions to the level necessary to achieve 
attainment. Similarly, operation and maintenance requirements and work 
practice controls are helpful for ensuring that process and control 
equipment are properly operated, but they do not correspond to or 
assure achievement of any particular level of emissions.
    The fugitive emissions studies, the first of which began last year, 
will provide better information regarding the actual level of fugitive 
emissions from the facility. However, these studies will last for only 
one year each and do not correspond to any numeric emission limit. 
Therefore, if one of the studies were to show that fugitive emissions 
exceeded the levels assumed in the attainment modeling, this would not 
constitute a violation of an emissions limit that could give rise to an 
enforcement action. Rather, it would simply trigger a requirement for 
Asarco to conduct new modeling to assess whether the NAAQS would still 
be attained at the higher emissions levels.\21\ If that modeling shows 
an increased likelihood of a NAAQS exceedance, then Asarco would have 
to submit to ADEQ a proposed revision to its operations and maintenance 
plan and associated modeling to demonstrate attainment of the NAAQS. 
ADEQ would then submit revisions to the operational limits and 
volumetric flow monitoring provisions, and a revised attainment 
demonstration to the EPA as a SIP revision.
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    \21\ See Arizona Administrative Code R18-2-C1302 Appendix 14 
paragraphs A.14.8 and 9.
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    There is substantial risk that fugitive emissions from the facility 
could cause or contribute to violations of the 2010 SO2 
NAAQS. Consequently, the Plan must assure that these emissions are 
limited in an enforceable manner. A process for future evaluation of 
fugitive emissions and potential future SIP revisions contingent on the 
results of that evaluation cannot substitute for enforceable 
limitations on fugitive emissions. Moreover, if fugitive emissions were 
to increase during the period between the two studies or after the 
second study, there would be no mechanism to address those increased 
emissions. In contrast, if the Plan were to rely on enforceable numeric 
fugitive emissions limits corresponding to the

[[Page 71550]]

modeled fugitive emissions levels, with ongoing monitoring, 
recordkeeping and reporting requirements, then an exceedance of any of 
these emissions levels would be a violation of the SIP that could 
result in an immediate enforcement action by ADEQ, the EPA, or a third 
party. Such an approach would satisfy the requirement of CAA section 
172(c)(6) for enforceable limits and other measures that provide for 
attainment of the 2010 SO2 NAAQS.
    Finally, Asarco lists the stack emission limits among the control 
measures that it believes are sufficient to demonstrate attainment. As 
discussed in our proposal, the stack emission limits would be 
enforceable were it not for the flaws in monitoring, recordkeeping and 
reporting requirements. In any case, the stack limits have no bearing 
on the SIP's flaw in not imposing an enforceable limit for fugitive 
SO2 emissions.
    For the foregoing reasons, we conclude that the requirements for 
enforceable limits and other measures that provide for attainment of 
the SO2 NAAQS under CAA section 172(c)(6) have not been 
satisfied.
    Comment: Asarco reiterates its view that the EPA's proposal is 
dismissive of the progress that Asarco has made in reducing total 
SO2 emissions at the Hayden smelter, and that it implies 
that fugitive emissions controls at the smelter are inadequate. Asarco 
cites emissions reductions observed based on the initial data collected 
during the first fugitive emissions study to assert that fugitive 
emissions are well below what is needed to ensure attainment of the 
2010 SO2 NAAQS.
    Response: The EPA acknowledges the progress that has been made to 
reduce SO2 emissions at the Hayden smelter. As discussed in 
Asarco's comments and in the TSD accompanying our proposed action on 
Rule B1302, Asarco's SO2 control strategy includes several 
equipment and process upgrades, including replacement of the 
electrostatic precipitator and flash furnace with a new vent gas 
baghouse system; replacement of five 13-foot diameter converters with 
new 15-foot diameter units that operate more efficiently; installation 
of extended secondary and tertiary hooding in the converter aisle to 
maximize ventilation gas capture during charging, transfer, and tapping 
operations; and improvements to the acid plant with an upgraded pre-
heater system.\22\ ADEQ has estimated that the converter retrofit 
project would reduce SO2 emissions from the smelter by 90 
percent between 2011 and 2019.
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    \22\ Rule B1302 TSD, 5.
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    With regards to the adequacy of the fugitive emissions controls, 
the EPA disagrees that there are sufficient data to conclude that 
fugitive emissions are below the level needed to ensure attainment. 
Asarco references emissions reductions based on initial data collected 
during the first fugitive emissions study, stating that ``[u]nder the 
Plan, fugitive emissions fall from a maximum annual average of 295 
pounds/hour to an average range between 4.3 and 39.8 pounds/hour.'' 
However, Asarco has not provided the hourly emissions data from 
specific roofline sources over an extended period that would be 
necessary to assess whether the recently monitored levels of fugitive 
emissions have been consistently at or below the levels necessary for 
attainment. Moreover, even if recent fugitive emissions have been below 
the modeled level, there is no assurance that these levels will be 
maintained over the long-term because, as described in the previous 
response, the Plan and Rule B1302 do not include any ongoing 
requirements to measure fugitive emissions or assure that these 
emissions remain low.
    Comment: Regarding the EPA's position that Rule B1302 subsection 
(E)(4) ``provides an option for alternative sampling points that could 
undermine the enforceability of the stack emission limit by providing 
undue flexibility to change sampling points without undergoing a SIP 
revision,'' \23\ the commenter states that the EPA's concern is not 
justified and lacks merit because the provision requires Asarco to 
demonstrate to ADEQ's satisfaction that the measurement ``would yield 
inaccurate results or would be technologically infeasible'' prior to 
using an alternative sampling point. Asarco asserts that it would be 
indefensible for the EPA to require inaccurate results be used to 
demonstrate attainment. Lastly, Asarco notes that it has recommended 
that ADEQ withdraw subsection (E)(4) because Asarco and ADEQ have 
agreed that the monitoring points are yielding acceptable results so 
this issue should be resolved upon ADEQ's submittal of a revised plan.
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    \23\ 85 FR 31118, 31120.
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    Response: The EPA disagrees that this issue lacks merit. The EPA is 
not suggesting that inaccurate sampling points be required to be used 
to demonstrate attainment, but rather that any change to sampling 
points should be the subject of EPA and public review through a SIP 
revision. As noted in our proposal, one of four basic principles that 
apply to all SIPs and control strategies is replicability, which means 
that ``where a rule contains procedures for changing the rule, 
interpreting the rule, or determining compliance with the rule, the 
procedures are sufficiently specific and non-subjective such that two 
independent entities applying the procedures would obtain the same 
result.'' \24\ We find that the language in Rule B1302 subsection 
(E)(4) allowing for ``measurement of the flow rate at an alternative 
sampling point'' where the measurement in the outlet of the control 
equipment ``would yield inaccurate results or would be technologically 
infeasible'' is too general and subjective to ensure that two 
independent entities applying this standard would reach the same 
conclusion. For example, ADEQ might find that measurement of stack gas 
volumetric flow rate in the outlet of a particular piece of 
SO2 control equipment is technologically infeasible in a 
situation where the EPA might conclude that such measurement is 
feasible. Moreover, the rule does not specify any procedures or 
criteria for determining whether measurement at the alternative 
sampling point would yield accurate and representative results. 
Therefore, this provision of the rule is inconsistent with the 
principle of replicability.
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    \24\ General Preamble, 13568.
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    As stated in the April 2019 Comment Letter conveying the EPA's 
comments to ADEQ regarding Rule B1302, the EPA agrees that withdrawal 
of subsection (E)(4) is appropriate and will resolve this issue, if 
such withdrawal occurs.
    Comment: Asarco objects to the EPA's position that Rule B1302 
subsection (E)(6) ``allows for nearly 10 percent of total facility 
SO2 emissions annually to be exempt from continuous 
emissions monitoring systems; this deficiency could compromise the 
enforceability of the main stack emission limit.'' \25\ The commenter 
asserts that there is no deficiency and the basis for disapproval lacks 
merit because the provision to allow Asarco to petition ADEQ to replace 
the continuous emissions monitoring system (CEMS) with annual stack 
testing and report emissions rates as a pounds per hour (lb/hr) or 
pounds per ton production factor would still allow calculation of the 
emissions rates. Asarco states that there were legitimate concerns that 
it would not be able to perform a relative accuracy test audit (RATA) 
of the CEMS due to the low concentrations of SO2 present, 
but that it has now determined that it can perform a RATA of the 
relevant CEMS

[[Page 71551]]

and has requested that ADEQ withdraw subsection (E)(6) in ADEQ's 
submittal of a revised plan to resolve this issue.
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    \25\ 85 FR 31118, 31120.
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    Response: The EPA disagrees that this issue lacks merit. While the 
rule language does provide for an emissions value that can allow for 
the calculation of an overall stack emissions rate, we do not consider 
this sufficient to ensure the enforceability of the one-hour main stack 
emissions limit given the large variability in hourly emissions from 
the Asarco facility. The commenter asserts that units encompassed by 
the provision typically emit less than 75 lb/hr SO2; 
however, we note that Asarco's emissions estimate for these units 
forecasts a maximum emission rate as high as 417 lb/hr SO2 
(out of a total 1,069.1 lb/hr or 1,518 lb/hr main stack limit).\26\ In 
addition, we note that source test results represent a ``snapshot'' of 
unit emissions (and of corresponding unit operations) at the time of 
the source test. Generally, source tests must be performed at 
approximately 80 to 100 percent of maximum operating levels, and 
emissions limits relying upon a source test for demonstrating 
compliance typically require continuous monitoring of one or more 
parameters of unit operation. This allows for the determination that 
unit operations are representative of source test conditions and 
ensures the validity of the source test result. Rule B1302 subsection 
(E)(6), however, relies solely on source test results for demonstrating 
compliance, which we do not consider sufficient to ensure 
enforceability of the main stack emissions limit. As stated in our 
April 2019 Comment Letter, the EPA agrees that withdrawal of subsection 
(E)(6) is appropriate and will resolve this issue, if such withdrawal 
occurs.
---------------------------------------------------------------------------

    \26\ See B-1j_Forecast_Emissions_20160927.xlsx in the rulemaking 
docket for this action.
---------------------------------------------------------------------------

    Comment: Asarco objects to the EPA's position that Rule B1302 
``lacks a method for measuring or calculating emissions from a shutdown 
ventilation flue; this omission could compromise the enforceability of 
the main stack emission limit.'' \27\ Asarco asserts that the concern 
is unfounded and lacks merit. Asarco explains the purpose of the 
shutdown ventilation flue and describes the procedure for calculating 
emissions for planned and unplanned shutdowns. Asarco notes that the 
procedure and resulting values are included in the SIP documentation 
but that to resolve the issue, it has requested that ADEQ revise the 
operation and maintenance plan requirements in the SIP to document the 
SO2 emitted during planned and unplanned use of the shutdown 
ventilation flue and require the use of the operation and maintenance 
plan value in compliance calculations.
---------------------------------------------------------------------------

    \27\ 85 FR 31118, 31120.
---------------------------------------------------------------------------

    Response: The EPA disagrees that the concern is unfounded and lacks 
merit. While the procedure for calculating emissions for planned and 
unplanned shutdowns and the value are included in supporting 
documentation for the Plan, they are not included in Rule B1302 or 
elsewhere in the SIP; therefore, they are not currently enforceable.
    Comment: Regarding the EPA's position that Rule B1302 ``lacks a 
method for calculating hourly SO2 emissions,'' \28\ Asarco 
asserts that the calculation method is presented in subsections (F)(1) 
and (F)(2) and acknowledges that there was a typographical omission of 
the ``valid hour'' definition that was included in Arizona's 
submission. Asarco notes that it has submitted to ADEQ the same 
definition included in the EPA-approved plan for the 2010 
SO2 NAAQS for the Miami, Arizona area and that Asarco has 
requested that ADEQ include it in a revised submittal to resolve the 
issue.
---------------------------------------------------------------------------

    \28\ Id.
---------------------------------------------------------------------------

    Response: The omission of the ``valid hour'' definition leads to 
ambiguity in how hourly emissions are calculated, thus undermining 
enforceability. However, the EPA agrees that inclusion of a ``valid 
hour'' definition will clarify the method for calculating hourly 
SO2 emissions for the Hayden facility and will resolve this 
issue, if submitted to the EPA in a future SIP revision.
    Comment: The commenter states that Asarco is disappointed that the 
EPA has not evaluated a fundamental part of the Hayden SO2 
control strategy--i.e., the ``dual limit.'' Asarco discusses its 
rationale for the dual limit, states that there is no basis for the EPA 
to question it, and states that it is presumptively approvable under 
the EPA's SO2 Guidance.
    Response: As noted in our proposal on Rule B1302, we are approving 
the main stack emission limit because it is more stringent than the 
existing requirements in state law, as well as new operational 
standards and monitoring, recordkeeping, and reporting requirements for 
the smelter.\29\ However, as noted in our proposed action on the Hayden 
SO2 Plan, we are not evaluating its adequacy to ensure 
attainment of the 2010 SO2 NAAQS because (1) ADEQ has not 
demonstrated that the emission limits in Rule B1302 are sufficient to 
provide for attainment, and (2) the stack emission limit is not fully 
enforceable due to various deficiencies in Rule B1302.\30\
---------------------------------------------------------------------------

    \29\ 85 FR 31113, 31115.
    \30\ 85 FR 31118, 31120.
---------------------------------------------------------------------------

    Comment: Asarco states that it disagrees with the EPA's conclusion 
that the modeling in the Hayden SO2 Plan is flawed. It notes 
that the revised modeling that was informally submitted to EPA staff 
indicates that the Converter Retrofit Project meets the RACM/RACT 
requirements and that Asarco's understands that the revised modeling 
will be submitted to the EPA as a SIP revision.
    Response: As discussed above, the EPA has not reviewed the revised 
modeling because, as Asarco acknowledges, it has not been formally 
submitted to the EPA as a SIP revision. The EPA's proposal to 
disapprove the RACM/RACT demonstration is based on the modeling that 
was submitted as part of the March 2017 SIP submittal. Both ADEQ and 
Asarco acknowledge the error in the modeling in the March 2017 
submittal. The EPA will review any revised modeling upon formal 
submission of such modeling to the EPA as a SIP revision.
    Comment: Asarco states that ADEQ intends to submit a SIP revision 
that includes updated modeling that shows attainment; removal of Rule 
B1302, Section (E)(4); removal of Rule B1302, Section (E)(6); a 
provision in the operation and maintenance plan to demonstrate the 
quantity of SO2 present during planned and unplanned use of 
the shutdown ventilation flue; and a ``valid hour'' definition that is 
the same as the definition in the approved Miami SO2 SIP. 
Asarco reiterates its position that the CAA does not require the Hayden 
SO2 SIP to include numeric fugitive emissions limits but 
notes that it is working with ADEQ to establish workable emissions 
limits and monitoring provisions for demonstrating compliance with such 
limits. Asarco also states that the submission of the SIP revision is 
imminent and recommends that the EPA prioritize action on the pending 
revised submittal rather than development of a new plan.
    Response: As discussed above, the EPA disagrees with the 
commenter's assertion that the CAA does not require enforceable 
emissions limitations for fugitive emissions. Section 172(c)(6) of the 
Act requires attainment plans to include ``enforceable emission 
limitations, and such other control measures, means or techniques'' as 
necessary and appropriate to provide for attainment. With regards to 
the SIP revision that ADEQ and Asarco have been working on, the EPA 
will review

[[Page 71552]]

the submittal for approvability under the applicable requirements of 
the CAA and EPA regulations once it has undergone ADEQ public notice 
and comment and been formally submitted to the EPA. While the EPA looks 
forward to reviewing the prospective submittal, the EPA must also 
fulfill its obligation under section 110(k) of the CAA to act on ADEQ's 
2017 submittal.

III. The EPA's Final Action

    For the reasons discussed in our proposed action and above, the EPA 
is finalizing our partial approval and partial disapproval of the 
Hayden SO2 Plan. The EPA is approving the emissions 
inventory element under CAA section 172(c)(3) and (4) and affirming 
that the State has met the new source review requirements for the 
Hayden SO2 NAA under section 172(c)(5). We are disapproving 
the attainment demonstration, RACM/RACT, enforceable emission 
limitations, RFP, and contingency measure elements because they do not 
meet the requirements of the CAA for the 2010 SO2 NAAQS. As 
a result of this final partial disapproval, the offset sanction in CAA 
section 179(b)(2) will be imposed 18 months after the effective date 
this action, and the highway funding sanction in CAA section 179(b)(1) 
six months after the offset sanction is imposed. A sanction will not be 
imposed if the EPA determines that a subsequent SIP submission corrects 
the identified deficiencies before the applicable deadline.

IV. Statutory and Executive Order Reviews

    Additional information about these statutes and Executive Orders 
can be found at http://www.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review and Executive 
Order 13563: Improving Regulation and Regulatory Review

    This action is not a significant regulatory action and was 
therefore not submitted to the Office of Management and Budget (OMB) 
for review.

B. Executive Order 13771: Reducing Regulations and Controlling 
Regulatory Costs

    This action is not an Executive Order 13771 regulatory action 
because SIP approvals, including limited approvals, are exempted under 
Executive Order 12866.

C. Paperwork Reduction Act (PRA)

    This action does not impose an information collection burden under 
the PRA because this action does not impose additional requirements 
beyond those imposed by state law.

D. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic 
impact on a substantial number of small entities under the RFA. This 
action will not impose any requirements on small entities beyond those 
imposed by state law.

E. Unfunded Mandates Reform Act (UMRA)

    This action does not contain any unfunded mandate as described in 
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect 
small governments. This action does not impose additional requirements 
beyond those imposed by state law. Accordingly, no additional costs to 
state, local, or tribal governments, or to the private sector, will 
result from this action.

F. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have 
substantial direct effects on the states, on the relationship between 
the national government and the states, or on the distribution of power 
and responsibilities among the various levels of government.

G. Executive Order 13175: Coordination With Indian Tribal Governments

    This action does not have tribal implications, as specified in 
Executive Order 13175, because the SIP is not approved to apply on any 
Indian reservation land or in any other area where the EPA or an Indian 
tribe has demonstrated that a tribe has jurisdiction, and will not 
impose substantial direct costs on tribal governments or preempt tribal 
law. Thus, Executive Order 13175 does not apply to this action.

H. Executive Order 13045: Protection of Children From Environmental 
Health Risks and Safety Risks

    The EPA interprets Executive Order 13045 as applying only to those 
regulatory actions that concern environmental health or safety risks 
that the EPA has reason to believe may disproportionately affect 
children, per the definition of ``covered regulatory action'' in 
section 2-202 of the Executive Order. This action is not subject to 
Executive Order 13045 because it does not impose additional 
requirements beyond those imposed by state law.

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

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

J. National Technology Transfer and Advancement Act (NTTAA)

    Section 12(d) of the NTTAA directs the EPA to use voluntary 
consensus standards in its regulatory activities unless to do so would 
be inconsistent with applicable law or otherwise impractical. The EPA 
believes that this action is not subject to the requirements of section 
12(d) of the NTTAA because application of those requirements would be 
inconsistent with the CAA.

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

    The EPA lacks the discretionary authority to address environmental 
justice in this rulemaking.

L. Congressional Review Act (CRA)

    This action is subject to the CRA, and the EPA will submit a rule 
report to each House of the Congress and to the Comptroller General of 
the United States. This action is not a ``major rule'' as defined by 5 
U.S.C. 804(2).

M. Petitions for Judicial Review

    Under section 307(b)(1) of the CAA, petitions for judicial review 
of this action must be filed in the United States Court of Appeals for 
the appropriate circuit by January 11, 2021. Filing a petition for 
reconsideration by the Administrator of this final rule does not affect 
the finality of this rule for the purposes of judicial review nor does 
it 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 CAA section 307(b)(2)).

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Nitrogen dioxide, Particulate 
matter, Reporting and recordkeeping requirements, Sulfur dioxide, 
Volatile organic compounds.

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

[[Page 71553]]

    Dated: October 10, 2020.
John Busterud,
Regional Administrator, Region IX.

    Part 52, Chapter I, Title 40 of the Code of Federal Regulations is 
amended as follows:

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. In 52.120(e), amend Table 1 under the heading ``Part D Elements and 
Plans (Other than for the Metropolitan Phoenix and Tucson Areas)'' by 
adding an entry for ``Arizona State Implementation Plan Revision: 
Hayden Sulfur Dioxide Nonattainment Area for the 2010 SO2 
NAAQS'' after the entry for ``SIP Revision: Hayden Lead Nonattainment 
Area, excluding Appendix C.''

Sec.  52.120  Identification of plan.

* * * * *
    (e) * * *

                       Table 1--EPA-Approved Non-Regulatory and Quasi-Regulatory Measures
       [Excluding certain resolutions and statutes, which are listed in tables 2 and 3, respectively] \1\
----------------------------------------------------------------------------------------------------------------
                                     Applicable
                                   geographic or
     Name of SIP provision         nonattainment     State submittal   EPA approval date        Explanation
                                   area or title/          date
                                      subject
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
               Part D Elements and Plans (other than for the Metropolitan Phoenix or Tucson Areas)
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
Arizona State Implementation     Hayden, AZ Sulfur  March 9, 2017....  [INSERT FEDERAL    Adopted by the Arizona
 Plan Revision: Hayden Sulfur     Dioxide                               REGISTER           Department of
 Dioxide Nonattainment Area for   Nonattainment                         CITATION],         Environmental Quality
 the 2010 SO2 NAAQS. Chapter 3,   Area.                                 November 10,       and submitted to the
 Chapter 8, Appendix A, and                                             2020.              EPA as an attachment
 Appendix B.                                                                               to letter dated March
                                                                                           8, 2017. The EPA
                                                                                           approved the
                                                                                           emissions inventory
                                                                                           element and affirmed
                                                                                           that the State had
                                                                                           met the new source
                                                                                           review requirements
                                                                                           for the area. The EPA
                                                                                           disapproved the
                                                                                           attainment
                                                                                           demonstration, RACM/
                                                                                           RACT, enforceable
                                                                                           emission limitations,
                                                                                           RFP, and contingency
                                                                                           measure elements.
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
\1\ Table 1 is divided into three parts: Clean Air Act Section 110(a)(2) State Implementation Plan Elements
  (excluding Part D Elements and Plans), Part D Elements and Plans (other than for the Metropolitan Phoenix or
  Tucson Areas), and Part D Elements and Plans for the Metropolitan Phoenix and Tucson Areas.

* * * * *

0
3. Section 52.124 is amended by revising paragraph (c) to read as 
follows:

Sec.  52.124  Part D disapproval.

* * * * *
    (c) The following portions of the ``Arizona State Implementation 
Plan Revision: Hayden Sulfur Dioxide Nonattainment Area for the 2010 
SO2 NAAQS'' are disapproved because they do not meet the 
requirements of Part D of the Clean Air Act:
    (1) Attainment demonstration,
    (2) Reasonably available control measures/reasonably available 
control technology,
    (3) Enforceable emission limitations,
    (4) Reasonable further progress, and
    (5) Contingency measures.

[FR Doc. 2020-23030 Filed 11-9-20; 8:45 am]
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