[Federal Register Volume 83, Number 33 (Friday, February 16, 2018)]
[Proposed Rules]
[Pages 6996-7002]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-03270]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2017-0537; FRL-9974-58--Region 9]


Air Plan Approval; Douglas, Arizona; Second 10-Year Sulfur 
Dioxide Maintenance Plan

AGENCY: Environmental Protection Agency (EPA).

[[Page 6997]]


ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve, as part of the State Implementation Plan (SIP) for the State 
of Arizona, the second 10-year maintenance plan for the Douglas 
maintenance area for the 1971 National Ambient Air Quality Standards 
(NAAQS or ``standards'') for sulfur dioxide (SO2).

DATES: Any comments on this proposal must be received by March 19, 
2018.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2017-0537 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, (415) 
972-3877, [email protected].

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

Table of Contents

I. Summary of Action
II. Background
    A. What NAAQS are considered in today's rulemaking?
    B. What is the background for this action?
    C. What are the applicable provisions for second 10-year 
maintenance plans for SO2?
III. The EPA's Evaluation of the Arizona Submittal
    A. Did the State meet the CAA procedural requirements?
    B. Has the State met the substantive maintenance plan 
requirements?
IV. Proposed Action and Request for Public Comment
V. Statutory and Executive Order Reviews

I. Summary of Action

    We are proposing to approve the second 10-year maintenance plan for 
the Douglas, Arizona SO2 maintenance area (``Douglas 
maintenance area'').\1\ Specifically, the EPA is proposing to approve 
the Douglas second 10-year maintenance plan for the 1971 NAAQS for 
SO2 under sections 110 and 175A of the Clean Air Act (CAA or 
``Act'') based on our determination that the plan fulfills all relevant 
requirements.
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    \1\ For the definition of the Douglas maintenance area, see 40 
CFR 81.303.
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II. Background

A. What NAAQS are considered in today's rulemaking?

    The NAAQS are health-based and welfare-based standards for certain 
ambient air pollutants. SO2 is the pollutant that is the 
subject of this action, and it is among the ambient air pollutants for 
which we have established health-based standards. SO2 causes 
adverse health effects by reducing lung function, increasing 
respiratory illness, altering the lung's defenses, and aggravating 
existing cardiovascular disease. Children, the elderly, and people with 
asthma are the most vulnerable. SO2 emissions also 
contribute to acidic deposition, damage to crops and vegetation, and 
corrosion of natural and man-made materials.
    In 1971 the EPA established both short- and long-term primary NAAQS 
for SO2. The short-term (24-hour) standard of 0.14 parts per 
million (ppm) was not to be exceeded more than once per year. The long-
term standard specifies an annual arithmetic mean not to exceed 0.030 
ppm.\2\ See 40 CFR 50.4.
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    \2\ Secondary NAAQS are promulgated to protect public welfare. 
The secondary 1971 SO2 NAAQS (3-hour) of 0.5 ppm is not 
to be exceeded more than once per year. The Douglas area was not 
classified nonattainment for the secondary standard, and this action 
relates only to the primary 1971 SO2 NAAQS.
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    In 2010 the EPA revised the primary SO2 NAAQS by 
establishing a new 1-hour standard of 75 parts per billion. The EPA 
revoked the existing 1971 primary standards at that time because they 
would not provide additional public health protection (75 FR 35550, 
June 22, 2010). Today's action relates only to the revoked 1971 NAAQS. 
The State has requested that we act on this maintenance plan.\3\
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    \3\ This action is consistent with the CAA's anti-backsliding 
provisions. The EPA's final rule on revocation of the 1971 
SO2 NAAQS discussed that maintenance SIPs would continue 
being implemented by states until they are subsumed by new planning 
and control requirements associated with the revised NAAQS, and that 
the revoked SO2 NAAQS would be retained for one year 
following the effective date of the initial designations for the 
2010 SO2 NAAQS in areas designated attainment (75 FR 
35520, June 22, 2010). On January 9, 2018, Cochise County was 
designated Attainment/Unclassifiable for the 2010 SO2 
NAAQS (83 FR 1098).
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B. What is the background for this action?

1. When was the nonattainment area established?
    The Douglas maintenance area is located in southern Cochise County 
near the U.S.-Mexico border. On March 3, 1978, for lack of a State 
recommendation, we designated Cochise County as a primary 
SO2 nonattainment area based on monitored violations of the 
primary SO2 NAAQS in the county between 1975 and 1977 (43 FR 
8968, March 3, 1978). At the request of the Arizona Department of 
Environmental Quality (ADEQ), the nonattainment area was subsequently 
reduced to three townships in and around Douglas (44 FR 21261, April 
10, 1979). Thus, the nonattainment area was composed of the following 
townships: T23S, R27E; T24S, R27E; and T24S, R28E. The remaining 
townships in Cochise County, T23S, R26E; T23S, R28E; and T24S, R26E, 
were designated as areas that ``cannot be classified.''
    On the date of enactment of the 1990 CAA Amendments, SO2 
areas meeting the conditions of section 107(d) of the Act were 
designated nonattainment for the SO2 NAAQS by operation of 
law. Section 107(d) describes the processes by which nonattainment 
areas are designated, including the pre-existing SO2 
nonattainment areas. Thus, the Douglas area remained nonattainment for 
the primary SO2 NAAQS following enactment of the 1990 CAA 
Amendments on November 15, 1990.
2. When was the Douglas area redesignated for SO2?
    In 2006 we redesignated the Douglas area using the criteria for 
SO2 nonattainment areas that have discontinued ambient 
monitoring following the closure of the major point source that caused 
the air quality violations (71 FR 9941, February 28, 2006). The 
criteria are described in a memorandum from John Seitz titled 
``Redesignation of Sulfur Dioxide Nonattainment Areas in the Absence of 
Monitored Data,'' (``Seitz Memo'').\4\
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    \4\ Memorandum dated October 18, 2000, from John Seitz, 
Director, EPA Office of Air Quality Planning and Standards, to 
Regional Office Air Division Directors, Subject: Redesignation of 
Sulfur Dioxide Nonattainment Areas in the Absence of Monitored Data.

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[[Page 6998]]

    During its operation, the Phelps Dodge Douglas Reduction Works 
Smelter (PDDRWS) was the largest point source in the Douglas 
SO2 nonattainment area, emitting approximately 330,000 tons 
of SO2 in 1985 and contributing more than 99 percent of 
total SO2 emissions that year. On January 15, 1987, the 
PDDRWS was permanently deactivated. The facility was completely 
dismantled by 1991. On January 30, 1992, the ADEQ confirmed that the 
facility was dismantled and no longer existed at the former site. On 
February 28, 2006, the EPA finalized approval of the maintenance plan 
and redesignation request for the Douglas area, effective May 1, 2006 
(71 FR 9941).
3. What is the current status of the area?
    The remaining SO2 point sources in the Douglas 
maintenance area consist of the Arizona Public Service Fairview 
Generating Station, which has a facility-wide potential to emit (PTE) 
of about 70 tons per year (tpy) of SO2; the Bisbee Douglas 
International and Douglas Municipal airports; and the Arizona State 
Prison Complex at Douglas. The 50-kilometer (km) buffer area required 
by the Seitz Memo to be evaluated includes areas within Arizona and 
Mexico. Most of the point sources in the Arizona portion are airports; 
non-airport sources include the Lhoist North America mine/lime plant, 
the Freeport Copper Queen mine, and the Fiesta Canning Co. food 
processing plant. The non-airport sources have a combined PTE of 4,425 
tpy SO2. The largest contributors of SO2 in the 
Mexican portion of the 50-km buffer area are the Agua Prieta II power 
plant and the Mexicana de Cobre mine/lime plant, which as of 2014, have 
estimated facility-wide PTEs of 30 tpy SO2 and 1,852 tpy 
SO2, respectively.\5\
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    \5\ Maintenance Plan Renewal, 1971 Sulfur Dioxide National 
Ambient Air Quality Standards, Douglas Maintenance Area (2016 
Douglas Second Maintenance Plan), page A-21. Prior to 2014, the 
Mexicana de Cobre facility included two boilers and a kiln, with an 
estimated PTE of 1,065 tpy SO2. In 2014, a second kiln 
was authorized at Mexicana de Cobre, resulting in a post-2014 
estimated facility-wide PTE of about 1,852 tpy.
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    Currently, no ambient SO2 monitors operate in the 
Douglas area. However, we do not expect the cumulative impact of the 
sources in and around Douglas to cause a violation of the NAAQS because 
the area's emissions are sufficiently low. No new sources of 
SO2 that are similar in size to the PDDRWS have located in 
the area since our redesignation of the area to attainment in 2006.

C. What are the applicable provisions for second 10-year maintenance 
plans for SO2?

1. What are the statutory provisions?
    Section 175A of the CAA provides the general framework for 
maintenance plans. The initial 10-year maintenance plan must provide 
for maintenance of the NAAQS for at least 10 years after redesignation, 
including any additional control measures necessary to ensure such 
maintenance. In addition, maintenance plans are to contain contingency 
provisions necessary to assure the prompt correction of a violation of 
the NAAQS that occurs after redesignation. The contingency measures 
must include, at a minimum, a requirement that the state will implement 
all control measures contained in the nonattainment SIP prior to 
redesignation.
    Section 175A(b) of the CAA requires states to submit a subsequent 
maintenance plan revision (``second 10-year maintenance plan'') eight 
years after redesignation. The Act requires only that this second 10-
year maintenance plan maintain the applicable NAAQS for 10 years after 
the expiration of the first 10-year maintenance plan. Beyond these 
provisions, section 175A of the CAA does not define the content of a 
second 10-year maintenance plan.
    Section 110 of the CAA requires states to make SIP revisions 
available for public review and comment and to hold a public hearing or 
provide the public the opportunity to request a public hearing. The Act 
requires the plan be adopted by the state and submitted to the EPA by 
the governor or his/her designee.
2. What general EPA guidance applies to SO2 maintenance 
plans?
    The primary guidance on maintenance plans and redesignation 
requests is a September 4, 1992 memorandum from John Calcagni, titled 
``Procedures for Processing Requests to Redesignate Areas to 
Attainment'' (``Calcagni Memo'').\6\ Specific guidance on 
SO2 redesignations also appears in a January 26, 1995 
memorandum from Sally L. Shaver, titled ``Attainment Determination 
Policy for Sulfur Dioxide Nonattainment Areas'' (``Shaver Memo'').\7\
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    \6\ Memorandum dated September 4, 1992, from John Calcagni, 
Director, EPA Air Quality Management Division, to Regional Office 
Air Division Directors, Subject: Procedures for Processing Requests 
to Redesignate Areas to Attainment.
    \7\ Memorandum dated January 26, 1995, from Sally L. Shaver, 
Director, EPA Air Quality Strategies and Standards Division, to 
Regional Office Air Division Directors, Subject: Attainment 
Determination Policy for Sulfur Dioxide Nonattainment Areas.
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    Guidance on SO2 maintenance plan requirements for an 
area lacking monitored ambient data, and where the area's historic 
violations were caused by a major point source that is no longer in 
operation, is found in the Seitz Memo (see section II.C.2). The Seitz 
Memo exempts eligible areas from the maintenance plan requirements of 
continued ambient air quality monitoring.
    While the Seitz Memo primarily addresses redesignations, we find it 
is appropriate to apply the Seitz Memo to second 10-year maintenance 
plans for areas that were redesignated in accordance with the memo and 
continue to experience similar conditions to those at the time of 
redesignation.
3. What are the requirements for maintenance plans for single-source 
SO2 nonattainment areas in the absence of monitored data?
    Our historic redesignation policy for SO2 has called for 
eight quarters of clean ambient air quality data as a prerequisite to 
redesignation of any area to attainment. The Seitz Memo provides 
guidance on SO2 maintenance plan requirements for an area 
lacking monitored ambient data and where the area's historic violations 
were caused by a major point source that is no longer in operation. To 
allow for these areas to qualify for redesignation to attainment, this 
policy requires that the maintenance plan address otherwise applicable 
provisions, and include:
    (1) Emissions inventories representing actual emissions when 
violations occurred, current emissions, and emissions projected to the 
tenth year after redesignation; all three inventories should include 
estimates of emissions in, and within a 50-km buffer zone of, the 
nonattainment area boundaries;
    (2) dispersion modeling showing that no SO2 NAAQS 
violations will occur over the next 10 years and that the retired 
source was the dominant cause of the high concentrations in the past;
    (3) evidence that if the retired source resumes operation, it would 
be considered a new source and be required to obtain a permit under the 
Prevention of Significant Deterioration (PSD) provisions of the CAA; 
and
    (4) a commitment to resume monitoring before any major 
SO2 source commences operation.

[[Page 6999]]

III. The EPA's Evaluation of the Arizona Submittal

A. Did the State meet the CAA procedural requirements?

    On December 14, 2016, the ADEQ submitted to the EPA the 
``Maintenance Plan Renewal, 1971 Sulfur Dioxide National Ambient Air 
Quality Standards, Douglas Maintenance Area'' (``2016 Douglas Second 
Maintenance Plan''). The State verified that it had adhered to its SIP 
adoption procedures in Appendix C to the 2016 Douglas Second 
Maintenance Plan, which includes the notice of public hearing, the 
agenda for the December 9, 2016 public hearing, the sign-in sheet, the 
public hearing officer certification and transcript of the hearing, and 
the State's responsiveness summary.
    On June 14, 2017, the 2016 Douglas Second Maintenance Plan was 
deemed complete by operation of law. See 40 CFR part 51, Appendix V, 
for the EPA's completeness criteria, which must be satisfied before 
formal review of the SIP.

B. Has the State met the substantive maintenance plan requirements?

1. Were the area's violations caused by a major point source of 
SO2 Emissions that is no longer in operation?
    As discussed above, the only major source of SO2 
emissions within the Douglas nonattainment area was the PDDRWS, which 
ceased operation in 1987. When the facility was in operation in 1985, 
the source emitted approximately 330,000 tons of SO2. The 
last recorded 24-hour or annual average exceedances of the primary 
NAAQS occurred in 1986, the last year of extensive monitoring. All but 
one monitor were removed before 1987 and all the remaining monitors 
owned and operated by Phelps Dodge and by the ADEQ near the PDDRWS were 
removed by 1988. The smelter operating permits expired, the smelting 
equipment was removed over a period of years, and the smelter was 
completely dismantled by 1991. No new sources of SO2 that 
are similar in size to the PDDRWS have located in the area. Thus, 
Douglas meets this criterion for review under the Seitz Memo.
2. Has the State met the requirements for second 10-year maintenance 
plans?
    The 2016 Douglas Second Maintenance Plan covers the second 10 years 
of the 20-year maintenance period, as required by section 175A(b) of 
the CAA. As discussed below, the State has addressed the requirements 
in the Seitz Memo for emissions inventories, modeling, permitting of 
major new sources, and agreement to commence monitoring if a new major 
source locates in the Douglas area. We provide more details on each 
requirement and how the 2016 Douglas Second Maintenance Plan meets each 
requirement in the following sections.
a. Emissions Inventories
    On December 14, 2001, the ADEQ submitted to the EPA the ``Douglas 
Sulfur Dioxide State Implementation and Maintenance Plan'' and request 
to redesignate the area to attainment (``2001 Douglas Maintenance 
Plan''). Following our request for additional information on emissions 
inventories and modeling, the ADEQ submitted a series of supplements to 
the EPA containing additional and revised technical information to 
support its redesignation request. The ADEQ's ``Douglas Sulfur Dioxide 
Nonattainment Area State Implementation Plan, Emissions Inventory and 
Air Quality Dispersion Modeling Update, September 2005'' (``2005 
Supplement'') included emissions inventories for sources in, and within 
50 km of, the Douglas maintenance area for 1985 when PDDRWS was 
operating and SO2 NAAQS violations occurred.
    In addition to reproducing emissions for 1985, the 2016 Douglas 
Second Maintenance Plan includes an emissions inventory representing 
current emissions for 2011 for sources in, and within 50 km of, the 
Douglas maintenance area. The ADEQ rolled the base 2011 inventory 
forward to generate an inventory for 2015, the final year of the first 
maintenance period, and similarly developed inventories for 2020, 2025, 
and 2030 to extend through the second 10-year maintenance period.
    The emissions inventories in the 2016 Douglas Second Maintenance 
Plan (see Section 3 and technical support document in Appendix A) 
include estimates of SO2 from all relevant source 
categories, which the plan divides among stationary, mobile, event-
related, and area source categories. The ADEQ used the EPA's 2011 
National Emissions Inventory and 2008 Inventario Nacional de Emisiones 
de M[eacute]xico to identify point sources in, and within 50 km of, the 
maintenance area. The plan includes a description of current facility 
types, emitting equipment, permitted emissions limits, operating rates, 
and emissions calculation methods.
    Table 1 presents a summary of actual SO2 emissions for 
1985 and 2011, and projected emissions for 2030 for sources in, and 
within 50-km of, the Douglas SO2 maintenance area. When the 
smelter was in operation in 1985, SO2 emissions exceeded 
330,000 tons. The ADEQ identified 965 tons of SO2 emissions 
in, and within 50-km of, the Douglas SO2 maintenance area in 
2011, and projected a maximum of 6,380 tons of SO2 emissions 
in 2030 based on growth projections and facility PTEs. Point source 
emissions in 2011 are lower than projected emissions in 2030 because 
facilities have not operated at their maximum PTE in recent years.

     Table 1--Actual (1985 and 2011) and Projected (2030) Douglas Maintenance Area SO2 Emissions (in tpy) a
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                                             Source category           1985            2011            2030
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Maintenance Area......................  Area, Mobile, and Event            93.02            5.60            3.22
                                         Sources.
                                        Point...................      330,000.14            0.30           69.75
50-km buffer..........................  Point (U.S.)............           21.02            0.43        4,424.98
                                        Point (Mexico)..........          904.84          959.02        1,882.25
                                                                 -----------------------------------------------
    Total.............................  ........................      331,019.02          965.35        6,380.20
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\a\ Source: 2016 Douglas Second Maintenance Plan, Tables 7, 8, and 10.

    Based on our review of the emissions inventories in the 2016 
Douglas Second Maintenance Plan, including the supporting information 
in Appendix A, we conclude that the inventories are complete, accurate, 
and consistent with applicable CAA provisions and the Seitz Memo.
b. Dispersion Modeling
    Past EPA policy memoranda on SO2 redesignations 
recommend dispersion modeling to show that the NAAQS is met and will be 
maintained. The Seitz Memo recommends dispersion modeling of all point 
sources within 50 km of the nonattainment area boundary. Screening 
modeling can be used to

[[Page 7000]]

conservatively estimate each source's contribution to average 
SO2 concentrations in the area.
    For the 2005 Supplement to the 2001 Douglas Maintenance Plan, 
screening dispersion modeling was performed using the SCREEN3 model run 
with conservative assumptions about source parameters and meteorology. 
In the 2005 Supplement, the ADEQ identified seven existing stationary 
sources in, and within 50 km of, the Douglas nonattainment area. The 
modeling analysis for emissions projected to 2015 indicated that the 
impact of these sources would not exceed 61 percent and 64 percent of 
the 1971 annual and 24-hour SO2 NAAQS, respectively.
    The Seitz Memo also requires a modeling analysis that shows that 
the retired point sources were the dominant sources contributing to 
high SO2 concentrations in the airshed. Since the emissions 
of non-smelter sources in the area had changed relatively little since 
the time that the smelter ceased operations, this same screening 
modeling was used to show that the smelter was the dominant source 
contributing to past high SO2 concentrations.
    For the 2016 Douglas Second Maintenance Plan, the ADEQ conducted a 
modeling analysis similar to the analysis for the 2005 Supplement. Five 
facilities for which SO2 emissions were projected to total 
at least 0.5 tpy in any future year were modeled. The ADEQ used the 
conservative approach of assuming that each facility would emit the 
maximum allowable SO2 in each future year. Other point 
sources were not modeled because of their small or negligible 
emissions; however, the collective impacts of such sources, in addition 
to area, mobile, and biogenic sources, were estimated based on 
SO2 concentrations observed by ambient air monitors in 
neighboring counties.
    The ADEQ used the EPA-recommended AERSCREEN dispersion model 
(version 15181) to estimate the SO2 impacts of the five 
facilities on maintenance in the Douglas planning area.\8\ AERSCREEN 
provides conservatively high concentration estimates by using worst 
case meteorology from among a range of meteorological conditions. The 
ADEQ used the conservative approach of summing the maximum AERSCREEN 
concentrations from each source, effectively assuming all concentration 
maxima occur at the same time and place. The results of the AERSCREEN 
modeling indicate a cumulative potential impact from 2015 to 2030 of 
the existing sources of less than 61 percent and 77 percent of the 1971 
annual and 24-hour SO2 NAAQS, respectively. See 2016 Douglas 
Second Maintenance Plan, p. 41-43.
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    \8\ AERSCREEN has replaced SCREEN3 as the EPA's preferred 
screening model. See memorandum dated April 11, 2011, from Tyler 
Fox, Leader, U.S. EPA Air Quality Modeling Group to EPA Regional 
Modeling Contacts, Subject: AERSCREEN Released as EPA Recommended 
Screening Model, in the docket for today's action.
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    One way that the ADEQ modeling was potentially not conservative was 
in its assumption of simple terrain. Terrain with elevations above 
stack height, i.e., ``complex terrain,'' can sometimes experience 
higher air quality impacts than simple terrain. While the Douglas 
Maintenance Area has low relief, it is not flat; it has a few isolated 
modest hills and elevations increase on its eastern edge towards the 
Perilla Mountains. To ensure that predicted SO2 
concentrations meet the NAAQS when terrain variability is considered, 
the EPA re-ran AERSCREEN for the sources with the largest maximum 
allowable emissions.\9\ Using a conservative approach that assumes 
worst-case meteorology and that all facility maxima occur at the same 
time, while more realistically accounting for where each facility 
maxima occurs in space, the EPA modeled maximum 24-hour and annual 
SO2 concentrations in the Douglas maintenance area that are 
below the NAAQS. The EPA's modeling results support the ADEQ's finding 
of continued attainment through 2030.
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    \9\ A modeling technical support document, which is available in 
the docket to this action, provides a detailed discussion of our 
analysis and findings.
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c. Treatment of New Sources of SO2 Emissions
    Section 172(c)(5) of the CAA requires New Source Review permits 
prior to the construction and operation of new major stationary sources 
and prior to major modifications at existing major stationary sources 
in nonattainment areas. However, in attainment areas, major sources and 
major modifications require PSD permits in accordance with section 165 
of the CAA. The PSD program requires stationary sources to apply the 
best available control technology (BACT) and ensure that projects will 
not cause or contribute to a violation of a NAAQS or a maximum 
allowable increase.
    The ADEQ has a PSD permitting program (i.e., Arizona Administrative 
Code (A.A.C.) R18-2-406) that was established to preserve the air 
quality in areas where ambient standards have been met. The PSD program 
requires stationary sources to undergo preconstruction review, install 
BACT, and conduct modeling demonstrating protection of the 
SO2 NAAQS. The program applies to any major source or major 
modification in the Douglas area. New minor sources are required to 
obtain a permit under A.A.C. R18-2-334, Arizona's Minor New Source 
Review program. Updates to the State's PSD and Minor New Source Review 
programs were approved into the SIP on November 2, 2015 (80 FR 67319). 
Thus, the ADEQ's existing PSD program satisfies the preconstruction 
permit provision of the Seitz Memo.
d. Commitment To Resume Monitoring
    The ADEQ commits to resume monitoring before any major source of 
SO2 commences to operate in the Douglas maintenance area. 
See 2016 Douglas Second Maintenance Plan, p. 26. Moreover, the PSD 
permit program requires that permit applicants conduct preconstruction 
monitoring to identify baseline concentrations. Together, these 
commitments address the monitoring provision of the Seitz Memo.
3. Other CAA Requirements
a. Contingency Plan
    As discussed above, section 175A of the CAA sets forth the 
statutory requirements for maintenance plans, and the Calcagni, Seitz, 
and Shaver memos cited above contain specific EPA guidance. The only 
maintenance plan element not covered by the Seitz Memo is the 
contingency provisions element. Section 175A(d) of the CAA requires 
that maintenance plans contain contingency provisions deemed necessary 
by the Administrator to assure that the state will promptly correct any 
violation of the standards that occurs after the redesignation of the 
area as an attainment area. The Calcagni Memo provides additional 
guidance, noting that although a state is not required to have fully-
adopted contingency measures that will take effect without further 
action by the state for the maintenance plan to be approved, the 
maintenance plan should ensure that the contingency measures are 
adopted expeditiously once they are triggered. Specifically, the 
maintenance plan should clearly identify the measures to be adopted, 
include a schedule and procedure for adoption and implementation of the 
measures, and contain a specific time limit for action by the state. In 
addition, the state should identify specific indicators or triggers 
that will be used to determine when the contingency measures need to be 
implemented.
    The 2016 Douglas Second Maintenance Plan includes the State's

[[Page 7001]]

commitment to continue to track maintenance of the SO2 NAAQS 
through updates to the emissions inventory. See 2016 Douglas Second 
Maintenance Plan, p. 44-45. Additionally, the ADEQ commits to 
reestablish an appropriate air quality monitoring network before any 
major source of SO2 begins operations in the Douglas 
maintenance area. See 2016 Douglas Second Maintenance Plan, p. 26.
    Since there are no remaining sources of SO2 emissions 
that are similar in size to the PDDRWS, the primary cause of any 
potential future violations of the 1971 SO2 NAAQS in the 
area would be from modified or new point sources. The ADEQ's current 
operating permit program places limits on SO2 emissions from 
existing sources. Should a new facility be constructed in the Douglas 
area or an existing facility want to upgrade or increase SO2 
emissions, the facility would also be subject to PSD as required by the 
Calcagni Memo.
    Furthermore, the ADEQ anticipates no relaxation of any implemented 
control measures used to attain and maintain the NAAQS, and they commit 
to submit to us any changes to rules or emission limits applicable to 
SO2 sources. The ADEQ also commits to maintain the necessary 
resources to promptly correct any violations of the provisions 
contained in the 2016 Douglas Second Maintenance Plan.
    Upon review of the contingency plan summarized above, we find that 
the ADEQ has established a contingency plan for the Douglas area that 
satisfies the requirements of the CAA section 175A(d) and the Calcagni 
Memo.
b. Transportation and General Conformity
    Conformity is required under section 176(c) of the CAA to ensure 
that federal actions are consistent with (``conform to'') the purpose 
of the SIP. Conformity to the purpose of the SIP means that federal 
activities will not cause new air quality violations, worsen existing 
violations, or delay timely attainment of the relevant NAAQS or interim 
reductions and milestones. Conformity applies to areas that are 
designated nonattainment and to maintenance areas. The requirement to 
determine conformity applies to transportation plans, programs, and 
projects developed, funded, or approved under Title 23 U.S.C. and the 
Federal Transit Act (``transportation conformity''), and to other 
federally supported or funded projects (``general conformity'').
    Transportation conformity applies to projects that require Federal 
Highway Administration or Federal Transit Administration funding. 40 
CFR part 93 describes the requirements for federal actions related to 
transportation plans, programs, and projects to conform to the purposes 
of the SIP. Because the EPA does not consider SO2 a 
transportation-related criteria pollutant, only the requirements 
related to general conformity apply to the Douglas area.\10\
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    \10\ See 40 CFR 93.102(b)(1).
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    Section 176(c)(4) of the CAA establishes the framework for general 
conformity. Besides ensuring that federal actions not covered by the 
transportation conformity rule will not interfere with the SIP, the 
general conformity regulations encourage consultation between the 
federal agency and the state or local air pollution control agencies 
before and during the environmental review process; public notification 
of and access to federal agency conformity determinations; and air 
quality review of individual federal actions.
    Section 176(c) of the CAA requires the states to revise their SIPs 
to establish criteria and procedures to ensure that federally supported 
or funded projects in nonattainment and maintenance areas ``conform'' 
to the air quality planning goals in the applicable SIP. State 
implementation plan revisions intended to meet the conformity 
requirements in section 176(c) are referred to as ``conformity SIPs.'' 
In 2005 Congress amended section 176(c), and under the amended 
conformity provisions, states are no longer required to submit 
conformity SIPs for general conformity, and the conformity SIP 
requirements for transportation conformity have been reduced to include 
only those relating to consultation, enforcement, and enforceability. 
See CAA section 176(c)(4)(E).
    The EPA believes it is reasonable to interpret the conformity SIP 
requirements as not applying for purposes of a redesignation request 
under section 107(d)(3)(E)(v) because state conformity rules are still 
required after redesignation and federal conformity rules apply where 
state rules have not been approved. See Wall v. EPA, 265 F. 3d 426 (6th 
Cir. 2001), upholding this interpretation. Because the Douglas area has 
already been redesignated for the 1971 SO2 NAAQS, we believe 
it is reasonable to apply the interpretation of conformity SIP 
requirements as not applying for the purposes of redesignation to the 
approval of the Douglas second 10-year maintenance plan.
    Criteria for making determinations and provisions for general 
conformity are contained in A.A.C. R18-2-1438. Arizona has an approved 
general conformity SIP (64 FR 19916, April 23, 1999).
    The ADEQ commits in the 2016 Douglas Second Maintenance Plan to 
review and comment, as appropriate, on any federal agency draft general 
conformity determination it receives consistent with 40 CFR 93.155 for 
any federal plans or actions in the Douglas area, although none are 
currently planned for the area. See 2016 Douglas Second Maintenance 
Plan, p. 20.

IV. Proposed Action and Request for Public Comment

    The EPA is proposing to approve the Douglas second 10-year 
SO2 maintenance plan under sections 110 and 175A of the CAA. 
As authorized in section 110(k)(3) of the Act, the EPA is proposing to 
approve the submitted SIP revision because it fulfills all relevant 
requirements.
    We will accept comments from the public on this proposal for 30 
days from the date of publication of this notice, and we will consider 
any relevant comments in taking final action on today's proposal.

V. 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. See 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 action:
     Is not a significant regulatory action subject to review 
by the Office of Management and Budget under Executive Orders 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

[[Page 7002]]

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).

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 2, 2018.
Alexis Strauss,
Acting Regional Administrator, EPA Region IX.
[FR Doc. 2018-03270 Filed 2-15-18; 8:45 am]
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