[Federal Register Volume 85, Number 100 (Friday, May 22, 2020)]
[Proposed Rules]
[Pages 31118-31124]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-10586]



[[Page 31118]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2020-0109; FRL-10008-99-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: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
partially approve and partially disapprove 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 proposing to approve the base year 
and projected emissions inventories and to affirm that the new source 
review requirements for the area have been met. We are proposing to 
disapprove 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 emission limitations and 
control measures, and contingency measures. We are taking comments on 
this proposal and plan to follow with a final action.

DATES: Any comments on this proposal must be received by June 22, 2020.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2020-0109, at https://www.regulations.gov, or via email to Ashley 
Graham, Air Planning Office at [email protected]. For comments 
submitted at Regulations.gov, follow the online instructions for 
submitting comments. Once submitted, comments cannot be removed or 
edited from Regulations.gov. For either manner of submission, the EPA 
may publish any comment received to its public docket. Do not submit 
electronically any information you consider to be Confidential Business 
Information (CBI) or other information whose disclosure is restricted 
by statute. Multimedia submissions (e.g., audio or video) must be 
accompanied by a written comment. The written comment is considered the 
official comment and should include discussion of all points you wish 
to make. The EPA will generally not consider comments or comment 
contents located outside of the primary submission (i.e., on the web, 
cloud, or other file sharing system). For additional submission 
methods, please contact the person identified in the FOR FURTHER 
INFORMATION CONTACT section. For the full EPA public comment policy, 
information about CBI or multimedia submissions, and general guidance 
on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Ashley Graham, EPA Region IX, Air 
Division, Air Planning Office, (415) 972-3877, [email protected].

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

Table of Contents

I. Why was Arizona required to submit a plan for the Hayden 
SO2 nonattainment area?
II. Requirements for SO2 Nonattainment Plans
III. Attainment Demonstration and Longer-Term Averaging
IV. Review of Modeled Attainment Demonstration
    A. Air Quality Modeling
    B. Emission Limits
    C. Summary of Results
V. Review of Other Plan Requirements
    A. Emissions Inventory
    B. Reasonably Available Control Measures and Reasonably 
Available Control Technology
    C. New Source Review
    D. Reasonable Further Progress
    E. Contingency Measures
VI. Conformity
VII. The EPA's Proposed Action
VIII. Statutory and Executive Order Reviews

I. Why was Arizona required to submit a plan for the Hayden 
SO2 nonattainment area?

    On June 22, 2010, the EPA promulgated a new 1-hour primary 
SO2 NAAQS of 75 parts per billion (ppb). 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 
a first set of 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 SIPs for areas 
designated as nonattainment for the SO2 NAAQS to the EPA 
within 18 months of the effective date of the designation, i.e., by no 
later than April 4, 2015, in this case (hereinafter called ``plans'' or 
``nonattainment plans''). Under CAA section 192(a), these plans are 
required to have measures that will provide for attainment of the NAAQS 
as expeditiously as practicable, but no later than five years from the 
effective date of designation, i.e., October 4, 2018, for the Hayden 
SO2 NAA.
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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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    For a number of areas, including the Hayden SO2 NAA, the 
EPA published a document on March 18, 2016, finding that Arizona and 
other pertinent states had failed to submit the required SO2 
nonattainment plan by the submittal deadline.\3\ The finding became 
effective on April 18, 2016, and 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), the 
finding triggered a requirement that the EPA promulgate a federal 
implementation plan within two years of the effective date of the 
finding unless by that time the state had made the necessary complete 
submittal and the EPA had approved the submittal as meeting applicable 
requirements.
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    \3\ 81 FR 14736.
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    In response to the requirement for SO2 nonattainment 
plan submittals, 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.\4\ 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).\5\
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    \4\ Letters dated March 8, 2017, and April 6, 2017, from Timothy 
S. 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.
    \5\ Letters dated July 17, 2017, and September 26, 2017, from 
Elizabeth Adams, Director, Air Division, EPA, Region IX to Timothy 
S. Franquist, Director, Air Quality Division, ADEQ.
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    The remainder of this preamble describes the requirements that 
nonattainment plans must meet in order to obtain EPA approval, provides 
a review of the Hayden SO2 Plan with respect to these 
requirements, and describes the EPA's proposed action on the Plan.

[[Page 31119]]

II. Requirements for SO2 Nonattainment Plans

    Nonattainment plans for SO2 must meet the applicable 
requirements of the CAA, specifically CAA sections 110, 172, 191, and 
192. 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'').\6\ Among other things, 
the General Preamble addressed SO2 SIP submissions and 
fundamental principles for SIP control strategies.\7\ On April 23, 
2014, the EPA issued recommended guidance for meeting the statutory 
requirements in SO2 SIP submissions, in a document entitled, 
``Guidance for 1-Hour SO2 Nonattainment Area SIP 
Submissions'' (``2014 SO2 Guidance''). In the 2014 
SO2 Guidance, the EPA described the statutory requirements 
for a complete nonattainment plan, including: 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 
emission limitations and control measures; and adequate contingency 
measures for the affected area.
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    \6\ 57 FR 13498 (April 16, 1992).
    \7\ Id. at 13548-13549, 13567-13568.
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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 to the EPA's satisfaction 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 nonattainment for 
any air pollutant may be modified in any manner unless it ensures 
equivalent or greater emission reductions of such air pollutant.

III. Attainment Demonstration and Longer-Term Averaging

    Sections 172(c)(1) and 172(c)(6) of the CAA direct states with 
areas designated as nonattainment to demonstrate that the submitted 
plan provides for attainment of the NAAQS. 40 CFR part 51, subpart G 
further delineates the control strategy requirements that plans must 
meet, and the EPA has long required that all SIPs and control 
strategies reflect four fundamental principles of quantification, 
enforceability, replicability, and accountability.\8\ SO2 
nonattainment plans must consist of two components: (1) Emission limits 
and other control measures that assure implementation of permanent, 
enforceable, and necessary emission controls, and (2) a modeling 
analysis that meets the requirements of 40 CFR part 51, appendix W and 
demonstrates that these emission limits and control measures provide 
for timely attainment of the primary SO2 NAAQS as 
expeditiously as practicable, but no later than the attainment date for 
the affected area. In cases where the necessary emission limits have 
not previously been made a part of the state's SIP or have not 
otherwise become federally enforceable, the plan needs to include the 
necessary enforceable limits in an adopted form suitable for 
incorporation into the SIP in order for the plan to be approved by the 
EPA. In all cases, the emission limits and control measures must be 
accompanied by appropriate methods and conditions to determine 
compliance with the respective emission limits and control measures and 
must be quantifiable (i.e., a specific amount of emission reduction can 
be ascribed to the measures), fully enforceable (i.e., specifying 
clear, unambiguous and measurable requirements for which compliance can 
be practicably determined), replicable (i.e., the procedures for 
determining compliance are sufficiently specific and non-subjective so 
that two independent entities applying the procedures would obtain the 
same result), and accountable (i.e., source specific limits must be 
permanent and must reflect the assumptions used in the SIP 
demonstrations).
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    \8\ Id. at 13567-13568.
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    The EPA's 2014 SO2 Guidance recommends that the emission 
limits be expressed as short-term average limits not to exceed the 
averaging time for the applicable NAAQS that the limit is intended to 
help maintain (e.g., addressing emissions averaged over one or three 
hours), but it also describes the option to utilize emission limits 
with longer averaging times of up to 30 days as long as the state meets 
various suggested criteria.\9\ The 2014 SO2 Guidance 
recommends that, should states and sources utilize longer averaging 
times (such as 30 days), the longer-term average limit should be set at 
an adjusted level that reflects a stringency comparable to the 1-hour 
average limit at the critical emission value shown to provide for 
attainment.
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    \9\ 2014 SO2 Guidance, 22-39.
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    The 2014 SO2 Guidance provides an extensive discussion 
of the EPA's rationale for concluding that appropriately set, 
comparable stringent limitations based on averaging times as long as 30 
days can be found to provide for attainment of the 2010 SO2 
NAAQS. In evaluating this option, the EPA considered the nature of the 
standard, conducted detailed analyses of the impact of use of 30-day 
average limits on the prospects for attaining the standard, and 
carefully reviewed how best to achieve an appropriate balance among the 
various factors that warrant consideration in judging whether a state's 
plan provides for attainment.\10\
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    \10\ Id. at 22-39, appendices B and D.
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    Preferred air quality models for use in regulatory applications are 
described in appendix A of the EPA's ``Guideline on Air Quality 
Models'' (40 CFR part 51, appendix W (``appendix W'')).\11\ In general, 
nonattainment SIP submissions must demonstrate the adequacy of the 
selected control strategy using the applicable air quality model 
designated in appendix W.\12\ However, where an air quality model 
specified in appendix W is inappropriate for the particular 
application, the model may be modified or another model substituted, if 
the EPA approves the modification or substitution.\13\ In 2005, the EPA 
promulgated the American Meteorological Society/Environmental 
Protection Agency Regulatory Model (AERMOD) as the Agency's preferred 
near-field dispersion model for a wide range of regulatory applications 
addressing stationary sources (e.g., in estimating SO2 
concentrations) in all types of terrain based on an extensive 
developmental and performance evaluation. Supplemental guidance on 
modeling for purposes of demonstrating attainment of the SO2 
standard is provided in appendix A of the 2014 SO2 Guidance. 
Appendix A provides extensive guidance on the modeling domain, the 
source inputs, assorted types of meteorological data, and

[[Page 31120]]

background concentrations. Consistency with the recommendations in the 
2014 SO2 Guidance is generally necessary for the attainment 
demonstration to offer adequately reliable assurance that the plan 
provides for attainment.
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    \11\ The EPA published revisions to appendix W on January 17, 
2017, 82 FR 5182.
    \12\ 40 CFR 51.112(a)(1).
    \13\ 40 CFR 51.112(a)(2); appendix W, section 3.2.
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    As stated previously, attainment demonstrations for the 2010 1-hour 
primary SO2 NAAQS must demonstrate future attainment and 
maintenance of the NAAQS in the entire area designated as nonattainment 
(i.e., not just at the violating monitor) by using air quality 
dispersion modeling (see appendix W) to show that the mix of sources 
and enforceable control measures and emission rates in an identified 
area will not lead to a violation of the SO2 NAAQS. For the 
short-term (i.e., 1-hour) standard, the EPA believes that dispersion 
modeling, using allowable emissions and addressing stationary sources 
in the affected area (and in some cases those sources located outside 
the NAA that may affect attainment in the area) is technically 
appropriate. This approach is also efficient and effective in 
demonstrating attainment in NAAs because it takes into consideration 
combinations of meteorological and source operating conditions that may 
contribute to peak ground-level concentrations of SO2.
    The meteorological data used in the analysis should generally be 
processed with the most recent version of AERMET, which is the 
meteorological data preprocessor for AERMOD. Estimated concentrations 
should include ambient background concentrations, follow the form of 
the standard, and be calculated as described in the EPA's August 23, 
2010 clarification memorandum.\14\
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    \14\ ``Applicability of Appendix W Modeling Guidance for the 1-
hr SO2 National Ambient Air Quality Standard'' (August 
23, 2010).
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IV. Review of Modeled Attainment Demonstration

A. Air Quality Modeling

    ADEQ's attainment demonstration used AERMOD version 15181, the 
regulatory version at the time it conducted its nonattainment planning. 
As input to AERMOD, ADEQ used one year of on-site surface 
meteorological data collected by ASARCO \15\ LLC (``Asarco'') between 
August 16, 2013, through August 15, 2014, at a 10-meter tower located 
approximately 0.35 kilometers south of the smelter building. After 
submittal, ADEQ discovered an error in the processing of the on-site 
surface meteorological data. Correcting this error changed predicted 
SO2 concentrations such that the modeling no longer shows 
attainment of the 2010 SO2 NAAQS. ADEQ has been working with 
Asarco and the EPA on revised modeling and intends to submit a new 
attainment demonstration and revised emission limits at a future 
date.\16\
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    \15\ ASARCO was organized in 1899 as the American Smelting And 
Refining COmpany.
    \16\ Email dated March 25, 2020, from Farah Esmaeili, ADEQ to 
Rynda Kay, EPA Region IX.
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B. Emission Limits

    An important prerequisite for approval of a nonattainment plan is 
the inclusion of ``enforceable emission limitations . . . as may be 
necessary or appropriate to provide for attainment of such standard in 
such area by the applicable attainment date . . . .''\17\ The emission 
limits that were intended to provide for attainment of the 2010 
SO2 NAAQS for the Hayden area are codified in the Arizona 
Administrative Code (AAC), Title 18, Chapter 2, Article 13, Section 
R18-2-B1302 (``Rule B1302''). ADEQ submitted Rule B1302 to the EPA on 
March 3, 2017. In a separate action, the EPA is proposing a limited 
approval and limited disapproval of Rule B1302. We are proposing a 
limited approval because the rule includes a more stringent 
SO2 emission limit for the main stack at the Hayden Smelter 
compared to the existing SIP-approved limit, as well as operational 
standards and monitoring, recordkeeping and reporting requirements that 
strengthen the SIP. At the same time, we are proposing a limited 
disapproval because of deficiencies in the rule's enforceability. Of 
particular relevance to the Hayden SO2 Plan, Rule B1302 does 
not contain any numeric fugitive emission limits or ongoing monitoring 
requirements corresponding to the levels of fugitive emissions that 
were modeled in the Plan. Instead, the rule relies on requirements in 
an operations and maintenance plan and two year-long fugitive emissions 
studies to verify compliance with the modeled fugitive emissions. While 
the fugitive emissions studies will provide useful information to 
verify the nature and extent of fugitive emissions from the facility, 
this approach does not satisfy the requirements for enforceable limits 
that provide for attainment of the SO2 NAAQS under CAA 
section 172(c)(6).
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    \17\ CAA section 172(c)(6). See also 57 FR 13498, 13567-13568 
(emission limits that provide for attainment be quantifiable, fully 
enforceable, replicable, and accountable).
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    In addition, Rule B1302 has several other deficiencies that 
undermine its enforceability in certain circumstances:
     Rule 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.
     Rule 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.
     The rule 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.
     The rule lacks a method for calculating hourly 
SO2 emissions; this omission makes it is unclear what 
constitutes a ``valid hour'' for purposes of allowing data 
substitution.\18\
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    \18\ Rule B1302, subsection (F)(2) contains a procedure for 
substituting emissions data for compliance demonstration purposes 
``when no valid hour or hours of data have been recorded by a 
continuous monitoring system.'' In the absence of a method for 
calculating hourly emissions, it is unclear when this procedure is 
to be used.
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    In light of these deficiencies, we propose to find that the Hayden 
SO2 Plan does not include emissions limits necessary to 
provide for attainment of the SO2 NAAQS.
    Finally, we note that the main stack emission limit in Rule B1302 
takes the form of a ``dual limit,'' under which ``[e]missions from the 
Main Stack shall not exceed 1069.1 pounds per hour on a 14-operating 
day average unless 1,518 pounds or less is emitted during each hour of 
the 14-operating day period.'' \19\ This dual limit is intended to 
provide a level of stringency comparable to a one-hour limit of 1,518 
pounds per hour. Because we are proposing to find (1) that ADEQ has not 
demonstrated the emission limits in Rule B1302 are sufficient to 
provide for attainment and (2) that the stack emission limit is not 
fully enforceable due to various deficiencies in Rule B1302, we have 
not evaluated whether the dual limit is of comparable stringency to a 
simple one-hour limit of 1,518 pounds per hour.
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    \19\ Rule B1302, subsection (C)(1).
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C. Summary of Results

    The EPA has reviewed ADEQ's submitted modeling supporting the 
attainment demonstration for the Hayden SO2 NAA and has 
preliminarily determined that this modeling is inconsistent with CAA 
requirements, appendix W, and the 2014 SO2 Guidance due to 
an error in the meteorological fields used. Without accurate modeling 
we are unable to

[[Page 31121]]

determine that the emission limits are sufficient for the Hayden 
SO2 NAA to attain the 2010 SO2 NAAQS. 
Furthermore, Rule B1302 does not include a numeric fugitive emissions 
limit and has other deficiencies related to the enforceability of the 
main stack emission limit. Therefore, we are proposing to disapprove 
the attainment demonstration in the Hayden SO2 Plan pursuant 
to 172(c) and 192(a).

V. Review of Other Plan Requirements

A. Emissions Inventory

    The emissions inventory and source emission rate data for an area 
serve as the foundation for air quality modeling and other analyses 
that enable states to estimate the degree to which different sources 
within a NAA contribute to violations within the affected area and 
assess the expected improvement in air quality within the NAA due to 
the adoption and implementation of control measures. The state must 
develop and submit to the EPA a comprehensive, accurate, and current 
inventory of actual emissions from all sources of SO2 
emissions in each NAA, as well as any sources located outside the NAA 
that may affect attainment in the area.\20\
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    \20\ CAA section 172(c)(3).
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    The base year inventory establishes a baseline that is used to 
evaluate emission reductions achieved by the control strategy and to 
assess RFP requirements. ADEQ used 2011 as the base year for emissions 
inventory preparation. At the time of preparation of the Plan, 2011 
reflected the most recent triennial National Emission Inventory, 
supported the requirement for timeliness of data, and was also 
representative of a year with violations of the primary SO2 
NAAQS. ADEQ reviewed and compiled actual emissions of all sources of 
SO2 in the NAA in the 2011 base year emissions inventory. In 
addition to developing an emissions inventory of SO2 
emission sources within the NAA, ADEQ also provided an SO2 
emissions inventory for those emission sources within a 50 kilometer 
buffer zone of the NAA. Table 1 summarizes 2011 base year 
SO2 emissions inventory data for the NAA, categorized by 
emission source type (rounded to the nearest whole number).

                                            Table 1--Base Year SO2 Emissions Inventory for the Hayden SO2 NAA
                                                                     [Tons per year]
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                                Year                                      Point           Nonpoint      On-road mobile  Non-road mobile       Total
--------------------------------------------------------------------------------------------------------------------------------------------------------
2011...............................................................          21,771                6               <1                2           21,779
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Source: Hayden SO2 Plan, Table 3-10.

    As shown in Table 1, the majority of SO2 emissions in 
the 2011 base year inventory can be attributed to the point source 
category. Emissions for this category are provided in further detail in 
Table 2.

         Table 2--Base Year Point Source SO2 Emissions Inventory
------------------------------------------------------------------------
                                                             Emissions
                      Point source                           (Tons per
                                                               year)
------------------------------------------------------------------------
Asarco LLC Hayden Smelter...............................          21,747
Asarco Ray Mine Complex.................................              24
                                                         ---------------
    Total...............................................          21,771
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Source: Hayden SO2 Plan, Table 3-3.

    A projected attainment year emissions inventory should also be 
included in the SIP submission according to the 2014 SO2 
Guidance. This emissions inventory should include, in a manner 
consistent with the attainment demonstration, estimated emissions for 
all SO2 emission sources that were determined to have an 
impact on the affected NAA for the projected attainment year. Table 3 
summarizes Arizona's projected 2018 SO2 emissions inventory 
data for the NAA, categorized by source type. The 2011 base year 
emissions, as well as the projected change between base year and 
projected year emissions, are also summarized (rounded to the nearest 
whole number).

                       Table 3--Projected 2018 Emissions Inventory for the Hayden SO2 NAA
                                                 [Tons per year]
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                                                                                     Non-road
              Year                     Point         Nonpoint     On-road mobile      mobile           Total
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2011............................          21,771               6              <1               2          21,779
2018............................           7,968               6              <1              <1           7,973
Change..........................         -13,803               0               0              -2         -13,806
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Source: Hayden SO2 Plan, Table 3-16.

    As shown in Table 3, both the majority of SO2 emissions 
in the projected 2018 emission inventory, as well as the majority of 
projected SO2 emission reductions, can be attributed to 
point sources. Emissions for this category were determined based on a 
potential to emit at 100 percent load capacity or federally enforceable 
permit

[[Page 31122]]

limits and are provided in further detail in Table 4. The single 
largest decrease in emissions is attributed to the Hayden Smelter.

                            Table 4--Projected 2018 Point Source Emissions Inventory
----------------------------------------------------------------------------------------------------------------
                                                                                       2018
                                                                  2011 Base year  Projected year
                          Point source                               emissions       emissions        Change
                                                                     (tons per       (tons per
                                                                       year)           year)
----------------------------------------------------------------------------------------------------------------
Asarco LLC Hayden Smelter.......................................          21,747         a 7,852         -13,895
Asarco Ray Mine Complex.........................................              24             116              92
                                                                 -----------------------------------------------
    Total.......................................................          21,771           7,968         -13,803
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Source: Hayden SO2 Plan, Table 3-11.
a Because Asarco was required to shut down five existing converters by May 2018, the 2018-projected emissions
  reflect a partial year of controls. Controls were required be fully implemented prior to 2019, during which
  emissions were projected to be 2,320 tons.

    The EPA has evaluated ADEQ's 2011 base year inventory and projected 
2018 emissions inventory for the Hayden SO2 NAA and finds 
these inventories and the methodologies used for their development to 
be consistent with EPA guidance. As a result, the EPA is proposing to 
determine that the Hayden SO2 Plan meets the requirements of 
CAA section 172(c)(3) and (4) for the Hayden SO2 NAA.

B. Reasonably Available Control Measures and Reasonably Available 
Control Technology

    ADEQ's Plan for attaining the 1-hour SO2 NAAQS in the 
Hayden SO2 NAA is based on implementation of controls at the 
Hayden Smelter. These controls include the replacement of the existing 
five converter units with three larger units, installation of more 
extensive, efficient, and effective fugitive gas control ducting around 
the converters, and the installation of additional process gas controls 
before venting to the main stack. These controls are collectively 
referred to as the ``Converter Retrofit Project.'' ADEQ conducted a 
RACM/RACT analysis in the Hayden SO2 Plan, comparing the 
requirements at the Hayden Smelter with controls in use at other large 
sources of SO2 to identify potentially available control 
measures and eliminating any measures that were not feasible at the 
Hayden Smelter or not more stringent than those measures already being 
implemented. ADEQ then compared the proposed control measures for the 
Hayden Smelter with the measures not eliminated in the first step of 
the RACM/RACT analysis and concluded that the proposed control measures 
would be more stringent. Our assessment of ADEQ's RACM/RACT analysis 
follows.
    The State's RACM/RACT analysis can be found in section 4.4.3 of the 
Hayden SO2 Plan. ADEQ compared SO2 controls at 
eight different facilities and found that all these units use an acid 
plant to recover or reduce SO2 emissions. Some of these 
facilities also use acid absorption equipment (wet and dry scrubbers) 
to further control emissions of SO2.
    ADEQ concluded that the Hayden Smelter's use of an acid plant, the 
Converter Retrofit Project, and dry lime scrubbing are comparable to 
SO2 control measures employed by similar sources. ADEQ 
reviewed the EPA's RACT/BACT/LAER Clearinghouse and air permits for 
facilities likely to have analogous processes as provided by the Air & 
Waste Management Association and determined that the Converter Retrofit 
Project controls for the Hayden Smelter are representative of RACM/RACT 
level of control.
    As explained in section IV of this document, we find that ADEQ has 
not demonstrated that implementation of the control measures required 
under the Plan is sufficient to provide for attainment of the NAAQS in 
the Hayden SO2 NAA because the modeling submitted with the 
attainment plan is flawed. As explained in the General Preamble, 
``control technology which failed to achieve the SO2 NAAQS 
would, by definition, fail to be SO2 RACT.'' \21\ Given that 
RACT is a necessary component of RACM under CAA section 172(c)(1), we 
propose to conclude that the State has not satisfied the requirement in 
CAA section 172(c)(1) to adopt and submit all RACM/RACT as needed to 
attain the standard as expeditiously as practicable.
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    \21\ 57 FR 13498, 13547.
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C. New Source Review

    On November 2, 2015, the EPA published a final limited approval and 
limited disapproval of revisions to ADEQ's new source review (NSR) 
rules.\22\ On May 4, 2018, the EPA approved additional rule revisions 
to address many of the deficiencies identified in the 2015 action.\23\ 
Collectively, these rule revisions ensure that ADEQ's rules provide for 
appropriate NSR for SO2 sources undergoing construction or 
major modification in the Hayden SO2 NAA without need for 
further modification. Therefore, the EPA has already concluded that the 
NSR requirement has been met for this area, and we are not reopening 
that determination in this proposed action. We note that Rule B1302 
subsection (I) (Preconstruction review) indicates that the smelter 
emission limits contained in the rule shall be determined to be 
SO2 RACT for purposes of minor NSR requirements. This 
provision does not interfere with or adversely affect existing 
nonattainment NSR rules.
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    \22\ 80 FR 67319.
    \23\ 83 FR 19631.
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D. Reasonable Further Progress

    In the Hayden SO2 Plan, Arizona explained its rationale 
for concluding that the Plan meets the requirement for RFP in 
accordance with EPA guidance. Specifically, ADEQ's rationale is based 
on EPA guidance interpreting the RFP requirement being satisfied for 
SO2 if the Plan requires ``adherence to an ambitious 
compliance schedule'' that ``implement[s] appropriate control measures 
as expeditiously as practicable.'' ADEQ noted that its Plan provides 
for attainment as expeditiously as practicable, i.e., by October 4, 
2018, and finds that the Plan thereby satisfies the requirement for 
RFP.
    ADEQ finds that the Hayden SO2 Plan requires affected 
sources to implement appropriate control measures as expeditiously as 
practicable to ensure attainment of the standard by the applicable 
attainment date. ADEQ concludes that the Plan provides for RFP in 
accordance with the approach to RFP described in the 2014 
SO2 Guidance.

[[Page 31123]]

    We note that the EPA's policy indicating RFP for SO2 may 
be satisfied by ``adherence to an ambitious compliance schedule'' is 
based on the fact that, ``for SO2 there is usually a single 
`step' between pre-control nonattainment and post-control attainment.'' 
\24\ In this instance, however, ADEQ has not demonstrated that 
implementation of the control measures required under the Plan is 
sufficient to provide for attainment of the NAAQS in the Hayden 
SO2 NAA. In the absence of a demonstration that the required 
controls will lead to attainment, a compliance schedule to implement 
these controls is not sufficient to provide for RFP. Therefore, we 
propose to conclude that the State has not satisfied the requirement in 
section 172(c)(2) to provide for RFP toward attainment in the Hayden 
SO2 NAA.
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    \24\ 2014 SO2 Guidance, 40.
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E. Contingency Measures

    In the Hayden SO2 Plan, ADEQ explained its rationale for 
concluding that the Plan meets the requirement for contingency 
measures. Specifically, ADEQ relies on the 2014 SO2 
Guidance, which notes the special circumstances that apply to 
SO2 and explains on that basis why the contingency 
requirement in CAA section 172(c)(9) is met for SO2 by 
having a comprehensive program to identify sources of violations of the 
SO2 NAAQS and to undertake an aggressive follow-up for 
compliance and enforcement of applicable emission limitations. ADEQ 
stated that it has such an enforcement program pursuant to state law in 
Arizona Revised Statutes (ARS) sections 49-461, 49-402, 49-404, and 49-
406. ADEQ also describes the process under state law to apply 
contingency measures for failure to make RFP and/or for failure to 
attain the SO2 NAAQS by the attainment date and concludes 
that ADEQ's Plan satisfies contingency measure requirements.
    We note that the EPA has approved ARS 49-402, 49-404, 49-406, and 
49-461 into the Arizona SIP.\25\ In addition, we have approved ARS 49-
422(A) (``Powers and Duties''), which authorizes ADEQ to require 
sources of air contaminants to ``monitor, sample or perform other 
studies to quantify emissions of air contaminants or levels of air 
pollution that may reasonably be attributable to that source'' for 
purposes of determining whether the source is in violation of a control 
requirement. We have also approved ARS 49-460 through 49-463, which 
authorize ADEQ to request compliance-related information from sources, 
to issue orders of abatement upon reasonable cause to believe a source 
has violated or is violating an air pollution control requirement, to 
establish injunctive relief, to establish civil penalties of up to 
$10,000 per day per violation, and to conduct criminal enforcement, as 
appropriate, through the Attorney General.\26\ Therefore, we agree that 
the Arizona SIP establishes a comprehensive enforcement program, 
allowing for the identification of sources of SO2 NAAQS 
violations and aggressive compliance and enforcement follow-up.
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    \25\ 40 CFR 52.120(e), Table 3.
    \26\ 77 FR 66398 (November 5, 2012).
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    However, the EPA's policy that a comprehensive enforcement program 
can satisfy the contingency measures requirement is premised on the 
idea that full compliance with the controls required in the plan will 
assure attainment. In this case, as explained above, ADEQ has not 
demonstrated that implementation of the control measures required under 
the Plan is adequate to provide for RFP and attainment of the NAAQS in 
the Hayden SO2 NAA. Accordingly, there is no evidence that a 
program to enforce these controls would be sufficient to bring the area 
into attainment in the event of NAAQS violations after the attainment 
date. Furthermore, the enforceability of these control measures is 
undermined by the deficiencies in Rule B1302 described in section IV.B. 
Therefore, we propose to conclude that the State has not satisfied the 
requirement in section 172(c)(9) to provide for contingency measures to 
be undertaken if the area fails to make RFP or to attain NAAQS by the 
attainment date.

VI. Conformity

    Generally, as set forth in section 176(c) of the CAA, conformity 
requires that actions by federal agencies do not cause new air quality 
violations, worsen existing violations, or delay timely attainment of 
the relevant NAAQS. General conformity applies to federal actions, 
other than certain highway and transportation projects, if the action 
takes place in a NAA or maintenance area (i.e., an area which submitted 
a maintenance plan that meets the requirements of section 175A of the 
CAA and has been redesignated to attainment) for ozone, particulate 
matter, nitrogen dioxide, carbon monoxide, lead, or SO2. The 
EPA's General Conformity Rule establishes the criteria and procedures 
for determining if a federal action conforms to the SIP.\27\ With 
respect to the 2010 SO2 NAAQS, federal agencies are expected 
to continue to estimate emissions for conformity analyses in the same 
manner as they estimated emissions for conformity analyses under the 
previous NAAQS for SO2. The EPA's General Conformity Rule 
includes the basic requirement that a federal agency's general 
conformity analysis be based on the latest and most accurate emission 
estimation techniques available.\28\ When updated and improved emission 
estimation techniques become available, the EPA expects the federal 
agency to use these techniques.
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    \27\ 40 CFR 93.150 to 93.165.
    \28\ 40 CFR 93.159(b).
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    Transportation conformity determinations are not required in 
SO2 nonattainment and maintenance areas. The EPA concluded 
in its 1993 transportation conformity rule that highway and transit 
vehicles are not significant sources of SO2. Therefore, 
transportation plans, transportation improvement programs, and projects 
are presumed to conform to applicable implementation plans for 
SO2.\29\
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    \29\ 58 FR 3768, 3776 (January 11, 1993).
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VII. The EPA's Proposed Action

    The EPA is proposing to partially approve and partially disapprove 
portions of the Hayden SO2 Plan, which includes ADEQ's 
attainment demonstration for the Hayden SO2 NAA and 
addresses requirements for RFP, RACM/RACT, base year and projected 
emissions inventories, new source review, and contingency measures. The 
EPA proposes to determine that the Hayden SO2 Plan meets the 
emissions inventory requirements under CAA section 172(c)(3) and (4) 
and to affirm that the State has met the new source review requirements 
for the Hayden SO2 NAA under section 172(c)(5). We propose 
to determine that the Hayden SO2 Plan does not meet the 
attainment demonstration, RACM/RACT, enforceable emission limitations, 
RFP, or contingency measure requirements of the CAA for the 2010 
SO2 NAAQS. Final partial disapproval of the Hayden 
SO2 Plan would trigger sanctions under CAA section 179 and 
40 CFR 52.31 unless the EPA determines that Arizona has corrected the 
deficiencies within 18 months of the effective date of the final 
action.
    The EPA is taking public comments for 30 days following the 
publication of this proposed action in the Federal Register. We will 
take all relevant timely comments into consideration in our final 
action.

[[Page 31124]]

VIII. Statutory and Executive Order Reviews

    Additional information about these statutes and Executive Orders 
can be found at http://www2.epa.gov/laws-regulations/laws-and-executive-orders.

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

    This action is not a significant regulatory action and 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 expected to be an Executive Order 13771 
regulatory action because this action is not significant 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 Population

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

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.

    Dated: May 12, 2020.
John Busterud,
Regional Administrator, Region IX.
[FR Doc. 2020-10586 Filed 5-21-20; 8:45 am]
 BILLING CODE 6560-50-P