
[Federal Register Volume 84, Number 48 (Tuesday, March 12, 2019)]
[Rules and Regulations]
[Pages 8813-8820]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-04389]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2017-0621; FRL-9990-40-Region 9]


Approval and Promulgation of Air Quality Implementation Plans; 
Arizona; Nonattainment Plan for the Miami SO2 Nonattainment Area

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is approving an 
Arizona state implementation plan (SIP) revision for attaining the 2010 
1-hour sulfur dioxide (SO2) primary national ambient air 
quality standard (NAAQS or ``standard'') for the Miami, Arizona 
SO2 nonattainment area (NAA). This SIP revision (hereinafter 
called the ``Miami SO2 Plan'' or ``Plan'') includes 
Arizona's attainment demonstration and other elements required under 
the Clean Air Act (CAA or ``Act''). In addition to an attainment 
demonstration, the Plan addresses the requirements for meeting 
reasonable further progress toward attainment of the NAAQS, reasonably 
available control measures and reasonably available control technology, 
base-year and projected emission inventories, enforceable emissions 
limitations and control measures, and contingency measures. The EPA 
concludes that the Plan provides for attainment of the 2010 1-hour 
primary SO2 NAAQS in the Miami SO2 NAA by the 
attainment date of October 4, 2018, and meets the other applicable 
requirements under the CAA.

DATES: This final rule is effective on April 11, 2019.

ADDRESSES: The EPA has established a docket for this action under 
Docket ID No. EPA-R09-OAR-2017-0621. 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

[[Page 8814]]

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.

FOR FURTHER INFORMATION CONTACT: Krishna Viswanathan, EPA, Region IX, 
Air Division, Air Planning Office, (520) 999-7880 or 
viswanathan.krishna@epa.gov.

SUPPLEMENTARY INFORMATION: Throughout this document whenever, ``we,'' 
``us,'' or ``our'' is used, we mean the EPA.

Table of Contents

I. Background
II. Public Comments and Response to Comments
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 Miami SO2 NAA within 
Arizona.\2\ These area designations became effective on October 4, 
2013. Section 191 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, these 
SIP submissions are required to include measures that will bring the 
nonattainment area 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 Miami 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 entitled, 
``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; demonstration of reasonable 
further progress (RFP); implementation of reasonably available control 
measures (RACM) (including reasonably available control technology 
(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 13545-49, 13567-68.
    \5\ Guidance for 1-Hour SO2 Nonattainment Area SIP 
Submissions, April 23, 2014.
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    For the EPA to fully approve a SIP revision as meeting the 
requirements of CAA sections 110, 172, and 191-192 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 Miami 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), the 
finding triggered a requirement that the EPA promulgate a federal 
implementation plan (FIP) 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.
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    In response to the EPA's finding, the Arizona Department of 
Environmental Quality (ADEQ) submitted the Miami 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\ Today's final SIP approval terminates the 
EPA's duty to promulgate a FIP for the area.
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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 Miami 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 Response to Comments

    The EPA proposed to approve the Miami SO2 Plan on June 
15, 2018.\9\ As part of this action, we also proposed to approve the 
use of AERMOD v14134 and BLP (``BLP/AERMOD Hybrid Approach'') as an 
alternative model to represent emissions from the roofline of the Miami 
Smelter (``smelter'').\10\ The EPA's proposed action provided a 30-day 
public comment period. During this period, we received eight comment 
letters. Six of these comment letters raised issues that are outside of 
the scope of this rulemaking, including air quality in China, India, 
and other areas of the United States, wind power, and relations between 
the United States and Russia. We are not required to respond to these 
comments and are not doing so here. Two comment letters, one from the 
Arizona Mining Association (AMA) and one from the National Parks 
Conservation Association (NPCA), the Sierra Club (SC), and Arizona 
Mining Reform Coalition (AMRC) (collectively, ``the Non-Governmental 
Organizations'' or ``NGOs'') raised issues germane to this 
action.11 12 The EPA's summary of

[[Page 8815]]

germane comments and responses are provided below. All comments 
received on the proposal are included in the docket for this action.
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    \9\ 83 FR 27938, June 15, 2018.
    \10\ Id. at 27942.
    \11\ Letter dated July 16, 2018, from Steve Trussell, Executive 
Director, Arizona Mining Association, to Michael Stoker, Regional 
Administrator, EPA Region IX.
    \12\ Letter dated July 16, 2018, from Kevin Dahl, NPCA, Sandy 
Bahr, SC, and Roger Featherstone, AMRC, to Krishna Viswanathan, Air 
Division, EPA Region IX.
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A. Comments From the AMA

    Comment: The AMA expressed support for our proposed approval of the 
Miami SO2 SIP. In addition, the commenter specifically 
requested clarification of the following statement from our proposal:

    The EPA also acknowledges the concern that longer-term emission 
limits can allow short periods with emissions above the critical 
emissions value, which, if coincident with meteorological conditions 
conducive to high SO2 concentrations, could in turn 
create the possibility of a NAAQS exceedance occurring on a day when 
an exceedance would not have occurred if emissions were continuously 
controlled at the level corresponding to the critical emission 
value.

    The AMA requested that the EPA ``revise this discussion to make it 
clear that the evaluation of the longer-term limit is looking at 
whether additional hourly exceedances of the numeric portion of the 
NAAQS will occur rather than NAAQS exceedances.''
    Response: We note AMA's support for our proposed approval. With 
respect to the commenter's request for clarification, the commenter 
appears to be confusing the term ``NAAQS exceedance'' with ``NAAQS 
violation.'' The hourly exceedance of the level of a NAAQS is the same 
as a NAAQS exceedance as used in our proposal but is different from a 
NAAQS violation. As explained in our proposal:

    As specified in 40 CFR 50.17(b), the 1-hour primary 
SO2 NAAQS 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 is less than or equal to 75 
ppb. In a year with 365 days of valid monitoring data, the 99th 
percentile would be the fourth highest daily maximum 1-hour value. . 
. Because the standard has this form, a single hourly exceedance 
does not create a violation of the standard.\13\

    \13\ 83 FR 27940, June 15, 2018 (emphasis added).
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    To restate, when we use the term ``NAAQS exceedance'' (both in our 
proposal and in this document), we refer to an hourly exceedance of the 
75 ppb level, rather than to a NAAQS violation, which would occur only 
when the 3-year average of the annual 99th percentile of daily maximum 
1-hour average concentrations is greater than 75 ppb.

B. Comments From the NGOs

    Comment: The NGOs noted that Arizona was subject to a March 18, 
2016 ``Finding of Failure to Submit,'' and the EPA was therefore 
obligated to approve the SIP or promulgate a FIP if the SIP was not 
approved by April 18, 2018. They asserted that the SIP was not approved 
nor was a FIP in place by the deadline.
    Response: We acknowledge that the EPA did not approve a SIP 
revision or promulgate a FIP for the Miami SO2 NAA by April 
18, 2018, as required under CAA 110(c)(1)(A). However, with this final 
action to approve the Miami SO2 Plan, we are discharging our 
statutory obligation under CAA section 110(k)(2) to act on the SIP, and 
such approval terminates our FIP obligation under section 110(c)(1)(A) 
for the Miami SO2 NAA.
    Comment: The NGOs stated that the Miami, Arizona area had a design 
value of 105 ppb when designated nonattainment; whereas the 2014-2016 
design value was 200 ppb, and the 2015-2017 preliminary design value 
was 221 ppb. The commenters asserted that, because attainment is 
determined by averaging over three years, the area will remain in 
nonattainment on the October 4, 2018 attainment deadline even if 
readings were 0.0 ppb from this point forward. On this basis they 
concluded that, even though the control measures may be operational by 
October 4, 2018, the State has already failed to demonstrate attainment 
by the statutory deadline.
    Response: We disagree with this comment. We note that, contrary to 
the commenters' suggestion, the CAA does not require states with 
SO2 nonattainment areas to factually ``demonstrate 
attainment by the statutory deadline'' in the SIPs they submit 
containing the control measures that will achieve attainment. Rather, 
sections 172 and 192 of the CAA require states to submit SIP revisions 
that ``provide for attainment'' of the SO2 NAAQS by the 
attainment date. In our proposal, we described our interpretation of 
``provide for attainment'' and the rationale for finding that the Miami 
SO2 plan submitted by the State of Arizona does provide for 
attainment.\14\ In particular, Arizona's submittal provides modeling-
based evidence that establishes that the control measures required on 
the single source of emissions in the area are sufficient to yield air 
quality that attains the NAAQS by the attainment deadline.
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    \14\ 83 FR 27947, June 15, 2018.
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    The available monitoring data should not be interpreted as 
indicating that Arizona's SIP has failed to provide for timely 
attainment. The monitoring data cited by the commenter were collected 
before the full implementation of the measures in the Miami 
SO2 plan, which occurred in 2018.\15\ Therefore, these data 
are indicative of whether air quality met the standard prior to full 
implementation of the measures reflected in the modeling demonstration, 
but these data are not a reliable indicator of whether air quality, 
after implementation of all modeled relevant control measures, would be 
expected to meet the standard at the attainment deadline. In other 
words, these data are not indicative of the adequacy of the plan and 
its modeling demonstration to provide for NAAQS attainment. Instead, as 
the EPA explained in our 2014 SO2 Guidance and in numerous 
proposed and final SIP notices implementing the SO2 NAAQS, a 
key element of an approvable SIP is the required modeling demonstration 
showing that the remedial control measures and strategy are adequate to 
bring a previously or currently violating area into attainment. Given 
the form of the 2010 NAAQS as the 3-year average of the 99th percentile 
of the yearly distribution of 1-hour daily maximum SO2 
concentrations, it is often possible that the three-year period of 
monitored data will not reflect the actual air quality levels resulting 
from implementation of the newer remedial control measures implemented 
within that period. In such cases, as it is here, the more complete and 
representative analysis for informing action on a submitted SIP should 
focus on the results of newly implemented control measures required 
under the plan, rather than historical concentrations that do not 
reflect the results of the plan's required control measures. The former 
analysis explicitly addresses whether air quality will be attaining (as 
required) under the state's submitted plan, whereas the latter analysis 
may have little to no bearing on what will happen as a result of the 
plan. Therefore, in the context of reviewing the adequacy of those 
newer control measures to provide for newly attaining air quality under 
sections 172 and 192, we conclude that it is reasonable to focus on the 
modeling results that specifically account for those control measures 
and the resulting reductions

[[Page 8816]]

in SO2 emissions, rather than on monitored data that, in 
this case, do not represent air quality levels resulting from full 
implementation of the control measures in the Plan. In the Miami 
SO2 Plan, Arizona's modeling shows that implementation of 
the measures included in the Plan result in air quality that attains 
the NAAQS.
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    \15\ On December 19, 2017, FMMI notified the EPA and ADEQ that 
it had completed construction of the SO2 capture and 
control system upgrades and had initiated associated commissioning 
activities. Letter from Byron Belew, FMMI, to Alexis Strauss, EPA, 
and Timothy Franquist, ADEQ (December 19, 2017).
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    Under the CAA, a determination of whether an area has failed to 
attain is a separate action from the review of an attainment 
demonstration SIP. The EPA's SIP review occurs under CAA sections 
110(k), 172(c) and 192(a), while a determination of whether an 
SO2 NAA has failed to attain is governed by CAA section 
179(c)(1). Under section 110(k)(3), the EPA is required to approve a 
SIP submission that meets all applicable requirements of the CAA. For 
the reasons described in our proposal and elsewhere in this notice, we 
have concluded that the Miami SO2 Plan meets all such 
requirements, including the requirement in 172(c) and 192(a) to provide 
for attainment by the attainment date. This is the determination that 
is the subject of today's final SIP approval action.
    Separately, in a different action under section 179(c)(1) that is 
beyond the scope of today's final SIP approval action, the EPA must 
determine within six months of the attainment date whether an area has 
attained the NAAQS based on the area's air quality as of the attainment 
date. Accordingly, the EPA will in a separate action, analyze the 
pertinent information and determine whether the Miami SO2 
NAA attained the NAAQS by the attainment date in accordance with 
section 179(c)(1).
    In response to the part of the comment related to change in ambient 
values, we note that the 2009-2011 design value used to designate the 
NAA was based on SO2 data from the Miami Ridgeline monitor, 
which was the only SO2 monitor in the NAA at that time. The 
2015-2017 design value cited by the commenter was based on data from 
the Miami Jones Ranch Monitor, which was installed in 2013. Because of 
safety and infrastructure concerns, the Ridgeline monitor ceased 
operation on September 26, 2017, following EPA approval of the site's 
closure.\16\ As shown in Table 1, during the years that both the 
Ridgeline and Jones Ranch monitors had valid design values (2015 and 
2016), the design values for the Jones Ranch monitor were more than 50 
ppb higher than the design values for the Miami Ridgeline monitor. The 
change in design value noted by the commenters reflects the more recent 
design value information provided by the Miami Jones Ranch monitor and 
appears to be more the result of monitoring at a different location 
rather than a significant worsening of air quality as implied by the 
commenter. Again, however, the EPA is not taking any final action today 
under CAA section 179(c) to determine whether the Miami area factually 
attained the NAAQS by the attainment date, and our discussion of the 
monitoring data from the Ridgeline and the Jones ranch monitors 
presented here is for informational purposes only.
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    \16\ Letter dated September 19, 2017, from Elizabeth Adams, 
Acting Director, Air Division EPA Region IX, to Timothy Franquist, 
Director, Air Quality, ADEQ.

                                   Table 1--2010 1-hr SO2 NAAQS Design Values for Monitors in the Miami SO2 NAA (ppb)
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                  Site name                        AQS ID          2011         2012         2013         2014         2015         2016         2017
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Ridgeline \1\................................     04-007-0009          111          107          105          122          145          146          N/A
Jones Ranch \2\..............................     04-007-0011          N/A          N/A          N/A          N/A          199          200          221
Townsite \3\.................................     04-007-0012          N/A          N/A          N/A          N/A          196          194          159
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N/A = not available.
\1\ The Ridgeline monitor ceased operation on September 26, 2017, due to safety and infrastructure concerns.
\2\ The Jones Ranch monitor became operational on February 1, 2013.
\3\ The Townsite monitor site became operational on February 1, 2013.

    Comment: The commenters noted that the EPA stated that it agreed 
with the State's placement of modeling receptors, which relied on an 
ambient air boundary consisting of the facility's physical fence line 
as well as several boundary segments with no fence that the State 
inspected and concluded steep topography precludes public access. 
However, the commenters asserted that ``there is no EPA regulation or 
written policy stating that steep topography is not ambient air. 
Impacts in these areas should not be ignored in the modeling 
simulations, and thus, the State has not demonstrated that the proposed 
emission limit of 142.45 lb/hr provides for attainment of the 
SO2 NAAQS.''
    Response: Ambient air is defined as ``that portion of the 
atmosphere, external to buildings, to which the general public has 
access.'' \17\ The 2014 SO2 Guidance, Appendix A, Section 
5.2 states ``[t]he model receptor grid is unique to the particular 
situation and depends on the size of the modeling domain, the number of 
modeled sources, and complexity of the terrain. Receptors should be 
placed in areas that are considered ambient air (i.e., where the public 
generally has access) relative to a particular facility. . . .'' The 
EPA policy on excluding areas from ambient air has been stated in a 
series of letters and memoranda. In a 1980 letter from Administrator 
Douglas Costle to Senator Jennings Randolph,\18\ the EPA stated its 
policy that the exclusion from ambient air is available only for the 
atmosphere over land owned or controlled by the source and to which 
public access is precluded by a fence or other physical barriers, based 
on a case-by-case review of individual situations to ensure that the 
public is adequately protected. This represents the EPA's current 
policy with regard to ambient air. As part of a demonstration that an 
exclusion is appropriate, a source should take steps to preclude the 
general public from accessing the property by relying on some type of 
physical barrier, such as a fence, wall, or a natural obstruction.\19\ 
As a result, we disagree with the commenter's assertion that the EPA 
lacks a written policy that allows for steep topography to preclude 
public access to facility property. As described above, a natural 
obstruction, such as steep topography, may be considered to be part of 
an ambient air boundary, consistent with the regulatory definition of 
ambient air, if it is effective in

[[Page 8817]]

precluding the general public from accessing the property and can be a 
basis for excluding such area for receptor placement in the modeling.
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    \17\ 40 CFR 50.1(e).
    \18\ Letter dated December 19, 1980, from Douglas M. Costle, 
Administrator, EPA to Senator Jennings Randolph, Chairman, 
Environment and Public Works Committee.
    \19\ Memorandum dated June 22, 2007, from Stephen D. Page, 
Director, Office of Air Quality Planning & Standards, EPA to 
Regional Air Division Directors, ``Interpretation of `Ambient Air' 
In Situations Involving Leased Land Under the Regulations for 
Prevention of Significant Deterioration.'' As indicated in the 
attachment to this EPA memo at footnote 1, ``preclude'' does not 
necessarily imply that public access is absolutely impossible, but 
rather that the likelihood of such access is small.
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    We note that the EPA is currently evaluating this ambient air 
policy to consider whether access to property by the general public may 
be effectively precluded or deterred, consistent with the existing 
regulatory definition of ambient air, by means other than a fence or 
other physical barriers.\20\ Such a revision to our policy would not 
alter our finding that Arizona properly excluded receptors in areas 
owned or controlled by the source where steep topography precludes 
public access.
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    \20\ EPA Draft Guidance dated November 2018, ``Revised Policy on 
Exclusions from `Ambient Air.' '' https://www.epa.gov/nsr/forms/draft-guidance-revised-policy-exclusions-ambient-air.
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    Comment: The NGOs commented that according to the spreadsheet from 
the docket \21\ Freeport-McMoRan Miami Incorporated's (FMMI's) existing 
permit requires individual limits, on a pound per hour (lb/hr) basis, 
on the various SO 2 emitting processes. They asserted that 
our proposed action does not include a discussion as to why it is 
appropriate to now switch to a single facility-wide limit with a longer 
term (i.e., 30-day averaging basis).
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    \21\ See C.4 2015-07-13 FMMI Emissions Inventory--2015-07-13--
Past Actuals Using Sulfur Balance.
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    Response: First, we disagree with the commenter's characterization 
of ``switching'' from individual limits to a facility-wide limit, as it 
implies that these existing limits will either be replaced or cease to 
be applicable following the approval of the Miami SO2 Plan. 
The permit limits listed in the spreadsheet cited by the commenter are 
found in Attachment C of FMMI's title V permit.\22\ The limits are 
820.00 lb/hr for the Acid Plant Tail Gas Stack, 312.00 lb/hr for the 
Vent Fume Stack, and 1288 lb/hr for all fugitives.\23\ These existing 
limits were established under separate legal authority to meet separate 
regulatory requirements and will not be altered by the addition of the 
142.45 lb/hr limit (30-day rolling average) that applies to the entire 
facility under Arizona Administrative Code, Title 18, Chapter 2, 
Article 13, Section R18-2-C1302 (``Rule C1302'').\24\
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    \22\ The spreadsheet cited by the commenter (i.e., ``C.4 2015-
07-13 FMMI--Emissions Inventory--2015-07-13--Past Actuals Using 
Sulfur Balance'') refers to Title V Permit 53592, which was issued 
on November 26, 2012, and expired on November 25, 2017. FMMI's 
current Title V Permit 66039, which was issued on December 20, 2019, 
includes the same emissions limits in Attachment C as Title V Permit 
53592.
    \23\ Title Permit 66039, Attachment C.
    \24\ The EPA approved Rule C1302 into the Arizona SIP at 83 FR 
56736 (November 14, 2018).
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    Second, we note that these existing individual limits were not in 
the SIP and were not intended to provide for attainment of the NAAQS. 
The appropriateness of the facility-wide, 30-day rolling emission limit 
for attainment of the NAAQS must be evaluated based upon the legal 
requirements and guidance associated with implementation of the 1-hr 
SO2 NAAQS. Contrary to the commenter's assertion, our 
proposal did explain why it is appropriate to use both a facility-wide 
limit and a longer-term limit in this case.\25\ As explained in the 
proposal, the State provided an analysis to show that due to the batch 
nature of the smelting process at the Miami Smelter, the emissions from 
the various units (``sources'') at the facility are independent of one 
another and therefore do not peak at the same time. The collection of 
future maximum potential SO2 emission rates for each source 
represents a conservative estimate of the worst-case emission 
distribution at the smelter. Additionally, ADEQ submitted an analysis 
that demonstrates that variations in the location of peak emissions 
among sources will not affect attainment, and a facility-wide emissions 
limit is sufficiently protective.
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    \25\ 83 FR 27938, June 15, 2018.
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    Comment: The commenters asserted that the adjustment factor used to 
develop the emission limit for the Miami Smelter (0.37) indicates that 
its operation is much more variable than are emissions at electric 
generating units (EGUs) and that the EPA's 2014 SO2 Guidance 
was developed based on empirical evidence to assess the variability of 
the operation of EGUs, not sulfuric acid plants. They argued that this 
greater variability means that there is much higher probability that 
any given hour is above the critical emission value (CEV) for this 
sulfuric acid plant relative to the EGUs cited in the 2014 
SO2 Guidance. They asserted that there was no discussion of 
the estimated percentage of time that the hourly emissions are expected 
to be above the CEV and that the EPA or the State, at a minimum, should 
provide some discussion on expected emissions and assess the 
variability in terms of sulfuric acid plants rather than EGUs.
    Response: We agree that emissions at the Miami Smelter are more 
variable than for EGUs. The adjustment factor for the Miami Smelter was 
0.37 compared to the national average adjustment factors (i.e., 0.63-
0.79) estimated for EGUs and listed in Table 1 of Appendix D of the 
2014 SO2 Guidance. The approach outlined in the 2014 
SO2 Guidance accounts for whatever degree of variability a 
source has, because the adjustment factor is designed to reflect the 
source's own emission distribution and variability. The higher degree 
of adjustment for the Miami Smelter compared to the EGUs means that the 
longer-term emission limit for the smelter is lowered further to ensure 
that hourly emissions exceeding the CEV are a rare occurrence. Indeed, 
the protocol given in the 2014 SO2 Guidance is designed to 
provide for long-term average emission levels above the long-term 
average limit to be as rare as 1-hour emission levels above the CEV, 
which for the Miami Smelter necessitates more adjustment than is 
necessary for most EGUs. Therefore, we disagree with the commenters 
that this increased variability means there is a higher probability 
that any given hour is above the CEV compared to the sources envisioned 
by the 2014 SO2 Guidance. As described in our proposal, the 
State used hourly SO2 data collected using continuous 
emission monitors from May 2013 to October 2014, adjusted to account 
for Miami Smelter's upgrades and increased production capacity, as a 
representative emission distribution for the smelter's future 
configuration.\26\ Appendix C to the Miami SO2 Plan, 
''Modeling Technical Support Document for the Miami Sulfur Dioxide 
(SO2) Nonattainment Area'' (``Modeling TSD''), Table 8-7 
specifies this representative emission distribution includes 60 hours 
above the CEV, which amounts to 0.5 percent of operating hours. The 
EPA's 2014 SO2 Guidance states that ``if above the critical 
emission value are a rare occurrence at a source, these periods would 
be unlikely to have a significant impact on air quality, insofar as 
they would be very unlikely to occur repeatedly at the times when the 
meteorology is conducive for high ambient concentrations of 
SO2.'' \27\ We conclude that the limit for the Miami 
Smelter, which we expect to result in no more than 0.5 percent of hours 
exceeding the CEV, qualifies as assuring that such occasions of 
elevated emissions will be sufficiently rare to provide for attainment, 
consistent with EPA guidance.
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    \26\ 83 FR 27944, June 15, 2018.
    \27\ 2014 SO2 Guidance, 24.
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    Comment: The NGOs argued that there should be a clear indication of 
whether or not there were hours of non-operation (i.e., zero emissions) 
for each of the emission units factored into the adjustment factor 
calculation and whether non-operation will be counted towards 
compliance. They noted that the 2014 SO2 Guidance calls for 
the

[[Page 8818]]

calculations to be made only during hours of operation and asserted 
that it was not clear how the State determined the 0.37 adjustment 
factor and how compliance will be ensured with respect to non-
operation.
    Response: We agree with the commenter that it should be clear how 
hours of non-operation were accounted for in developing the adjustment 
factor and how they will be used in determining compliance. Regarding 
the development of the adjustment factor, we have included information 
in the docket that displays the facility emission data used by the 
State in determining the 0.37 adjustment factor.\28\ This adjustment 
factor represents a ratio of the 99th percentile of 30-day average 
emissions relative to the 99th percentile of 1-hour average emissions. 
To determine the 99th percentile of the 1-hour average emissions, the 
State only considered hours corresponding to periods of operation. To 
determine the 99th percentile of the 30-day average emission values the 
State used a running hourly mean of the most recent 720 hours that 
corresponded to periods of operation. As seen in this spreadsheet, 
periods of zero emissions that correspond to nonoperation were removed 
from consideration in developing the adjustment factor.
---------------------------------------------------------------------------

    \28\ Spreadsheet ``FMMI_EMISSION_LIMIT_TSD_20151223.xls'' and 
Memorandum dated February 6, 2019, from Rynda Kay, EPA Region IX, 
Air Quality Analysis Office, to Rulemaking Docket EPA-R09-OAR-2017-
0621.
---------------------------------------------------------------------------

    We note that there was a period during June 16-17, 2015, in which 
39 hours of zero emissions were included in the set of emission data 
used in developing the adjustment factor. Additional correspondence 
between the EPA, ADEQ and FMMI provided further details indicating that 
while no emissions occurred, this period of time corresponds to a 
period of operation as defined in Rule C1302 subsection (B)(6).\29\ 
Specifically, FMMI indicated the electric furnace was receiving power 
during this period, and that electric furnace temperature was steadily 
increasing. In addition, the vent fume stack fan was also operating and 
ventilating during this period. FMMI asserts that during this 39-hour 
period, the electric furnace was operating and smelting, but that crust 
formation prevented SO2 emissions from the electric furnace 
until temperature was sufficient to melt the crust. Operating records 
provided by FMMI support these details and indicate that this 39-hour 
period represents initial startup after a period of nonoperation.\30\ 
Based on this information, we consider the inclusion of this 39-hour 
period appropriate because conditions at the facility were consistent 
with periods of operation that generated no emissions.
---------------------------------------------------------------------------

    \29\ Email dated September 19, 2018, from Farah Mohammadesmaeili 
(ADEQ) to Rynda Kay (EPA), Subject: ``FW: SO2 SIP Data 
Inquiry.''
    \30\ Spreadsheet ``2013 shutdown data 20181017.xlsx.''
---------------------------------------------------------------------------

    With respect to the compliance determination, we note that Rule 
C1302 subsection (F)(1) requires a compliance demonstration for each 
``operating day.'' Subsection (B)(6) of Rule C1302 defines ``operating 
day'' as any calendar day in which any of the following occurs:
    a. Concentrate is smelted in the Electric furnace or IsaSmelt 
furnace;
    b. Copper or sulfur bearing materials are processed in the 
converters;
    c. Blister or scrap copper is processed in the anode furnaces or 
mold vessel;
    d. Molten metal, including slag, matte or blister copper, is 
transferred between vessels;
    e. Molten metal is cast into molds, anodes, or other intermediate 
or final products;
    f. Power is provided to the electric furnace to make or maintain a 
molten bath; or
    g. The anode furnace is heated to make or maintain a molten bath.
    In this rule, compliance with the rolling 30-day emission limit is 
calculated by identifying the days during which one or more of the 
relevant units was actually operating, and at the end of each operating 
day computing average emissions over the most recent 30 operating days. 
The emissions from those 30 days are totaled and then divided by 720 
(30 days x 24 hours). The approach of determining compliance on the 
basis of emissions only during operating days and defining ``operating 
day'' as a day with any operation is consistent with the recommendation 
in the 2014 SO2 Guidance.\31\ On the other hand, the 
determination of compliance on a 720-hour basis, inherently averaging 
in the zero emission values of non-operating hours during an operating 
day, is not consistent with the recommendation in the 2014 
SO2 Guidance that hours without operation be excluded from 
the compliance determination.\32\
---------------------------------------------------------------------------

    \31\ 2014 SO2 Guidance, 32.
    \32\ Id. (``The MATS procedure also effectively provides that 
hours with no operation have no effect on the calculated average 
emission rate, which is a desirable feature in order to focus on how 
well controls are operating during operating hours.'')
---------------------------------------------------------------------------

    The EPA has evaluated the significance of using this compliance 
determination approach for this facility as compared to a method that 
excludes all non-operating hours.\33\ In the case of the Miami Smelter, 
the use of data only from operating days, as opposed to using data from 
all calendar days, substantially limits the inclusion of non-operating 
hours. The nature of the process at the Miami Smelter involves 
relatively continuous operation, so that the number of non-operating 
hours within operating days is minimal. For example, the emission data 
used to derive the adjustment factor, representing 12,264 hours, 
include only 224 non-operating hours, less than 2 percent of the hours. 
The inclusion of these non-operating hours has a negligible impact on 
the rolling average, especially at peak values for this facility. For 
example, the highest 30-operating day average calculated from the 
dataset is 105.9 lb/hr when non-operating hours are excluded compared 
to 105.2 lb/hr when non-operating hours are included. Both are well 
below the facility-wide 30-day emission limit of 142.45 lb/hr. Also, 
among the days represented in the top 10 percent of 30-day averages, 
only 0.5 percent of the hours are non-operating hours. As the 
compliance methodology for the Miami Smelter is based on an operating 
day, consistent with the 2014 SO2 Guidance, and the smelter 
operates continuously year-round, these non-operating hours remain 
inconsequential in determining compliance with the 30-day limit. 
Therefore, we conclude that this deviation from guidance will have 
minimal impact and does not prevent this Miami SO2 Plan from 
providing for attainment.
---------------------------------------------------------------------------

    \33\ See ``Evaluation-FMMIComplianceMethodology.xls'' for the 
EPA's evaluation of the Miami Smelter's compliance methodology.
---------------------------------------------------------------------------

    The 2014 SO2 Guidance also recommends that the approach 
used to calculate the adjustment factor should be consistent with the 
approach used to determine compliance with the longer-term limit.\34\ 
As described above, ADEQ computed the 99th percentile of the 30-day 
average emission values used in the development of the longer-term 
limit as a 720-rolling hourly average, whereas compliance is determined 
using a 30-operating day average. We recalculated the adjustment factor 
and resulting emission limit using the compliance methodology outlined 
in Rule C1302 and found the difference was small: The adjustment factor 
and 30-day limit are 0.368 and 141.80 lb/hr when calculated using a 30-
operating day average compared to 0.370 and 142.45 lb/hr when 
calculated as a 720-hour running mean, a 0.4 percent difference. We

[[Page 8819]]

believe this difference is negligible and the conservatism built into 
the State's modeling adequately demonstrates that the longer-term 
emission limit in Rule C1302 provides for attainment. The State's 
modeling predicts a design value of 194.1 micrograms per cubic meter 
([mu]g/m\3\), whereas the standard is 196.4 [mu]g/m\3\ (75 ppb), 
providing room for this slightly higher limit in Rule C1302.
---------------------------------------------------------------------------

    \34\ 2014 SO2 Guidance, Appendix C, C-3.
---------------------------------------------------------------------------

    Comment: The NGOs requested that the EPA take a fresh look at this 
rulemaking and issue a revised proposal for public notice and comment.
    Response: We have reexamined our proposed rulemaking and have 
concluded that no revised notice of proposed rulemaking is warranted. 
For the reasons described in our proposal and in the preceding 
responses to comments, we find that the Miami SO2 Plan meets 
all applicable requirements under the CAA and the EPA's implementing 
regulations. Accordingly, we are finalizing our approval of the Miami 
SO2 Plan.

III. The EPA's Final Action

    The EPA is approving the Miami SO2 Plan, which includes 
Arizona's attainment demonstration for the Miami SO2 NAA and 
addresses requirements for RFP, RACT/RACM, base-year and projected 
emission inventories, new source review, enforceable emissions limits 
and control measures, and contingency measures. For the reasons 
described in our proposal and the related concurrence documents,\35\ 
the EPA is also approving the BLP/AERMOD Hybrid Approach as an 
alternative model to represent emissions from Miami Smelter roofline in 
the Miami SO2 Plan under 40 CFR 51.112(a)(2). The EPA 
determines that the Miami SO2 Plan meets applicable 
requirements of sections 110, 172, 191 and 192 of the CAA for the 2010 
SO2 NAAQS.
---------------------------------------------------------------------------

    \35\ ``Concurrence Request for Approval of Alternative Model: 
BLP/AERMOD Hybrid Approach for Modeling Buoyant Roofline Sources at 
the FMMI Copper Smelter in Miami, AZ'' (March 12, 2018) and ``Model 
Clearinghouse Review of a BLP/AERMOD Hybrid Alternative Model 
Approach for Modeling Buoyant Roofline Sources at the FMMI Copper 
Smelter in Miami, AZ'' (March 26, 2018).
---------------------------------------------------------------------------

IV. Statutory and Executive Order Reviews

    Under the CAA, the Administrator is required to approve a SIP 
submission that complies with the provisions of the Act and applicable 
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in 
reviewing SIP submissions, the EPA's role is to approve state choices, 
provided that they meet the criteria of the CAA. Accordingly, this 
action merely approves state law as meeting Federal requirements and 
does not impose additional requirements beyond those imposed by state 
law. For that reason, this proposed action:
     Is not a ``significant regulatory action'' subject to 
review by the Office of Management and Budget under Executive Order 
12866 58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 
2011);
     Is not an Executive Order 13771 (82 FR 9339, February 2, 
2017) regulatory action because SIP approvals are exempted under 
Executive Order 12866;
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the CAA; and
     Does not provide the EPA with the discretionary authority 
to address, as appropriate, disproportionate human health or 
environmental effects, using practicable and legally permissible 
methods, under Executive Order 12898 (59 FR 7629, February 16, 1994).
    In addition, 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. In those areas of 
Indian country, the rule does not have tribal implications and will not 
impose substantial direct costs on tribal governments or preempt tribal 
law as specified by Executive Order 13175 (65 FR 67249, November 9, 
2000).
    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report, which includes a copy of the rule, 
to each House of the Congress and to the Comptroller General of the 
United States. The EPA will submit a report containing this action and 
other required information to the U.S. Senate, the U.S. House of 
Representatives, and the Comptroller General of the United States prior 
to publication of the rule in the Federal Register. A major rule cannot 
take effect until 60 days after it is published in the Federal 
Register. This action is not a ``major rule'' as defined by 5 U.S.C. 
804(2).
    Under section 307(b)(1) of the Clean Air Act, petitions for 
judicial review of this action must be filed in the United States Court 
of Appeals for the appropriate circuit by May 13, 2019. Filing a 
petition for reconsideration by the Administrator of this final rule 
does not affect the finality of this action for the purposes of 
judicial review 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 section 307(b)(2)).

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
Reference, Intergovernmental relations, Reporting and recordkeeping 
requirements, Sulfur oxides.

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

    Dated: February 21, 2019.
Deborah Jordan,
Acting Regional Administrator, EPA Region IX.
    40 CFR part 52 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 Sec.  52.120, table 1 in paragraph (e) is amended by adding the 
entry ``Arizona State Implementation Plan Revision: Miami Sulfur 
Dioxide Nonattainment Area for the 2010 SO2 NAAQS, excluding 
Appendix D'' after the entry ``SIP Revision: Hayden Lead Nonattainment 
Area, excluding Appendix C'' to read as follows:


Sec.  52.120  Identification of plan.

* * * * *
    (e) * * *

[[Page 8820]]



                                           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 area      State submittal date             EPA approval date                     Explanation
                                    or title/subject
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                   Part D Elements and Plans (Other Than for the Metropolitan Phoenix or Tucson Areas)
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
                                                                      * * * * * * *
Arizona State Implementation      Miami, AZ Sulfur     March 9, 2017..............  [insert Federal Register           Adopted by the Arizona Department
 Plan Revision: Miami Sulfur       Dioxide                                           citation], March 12, 2019.         of Environmental Quality on
 Dioxide Nonattainment Area for    Nonattainment Area.                                                                  March 8, 2017.
 the 2010 SO2 NAAQS, excluding
 Appendix D.
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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.

* * * * *
[FR Doc. 2019-04389 Filed 3-11-19; 8:45 am]
BILLING CODE 6560-50-P


