The Acting EPA Regional Administrator, Alexis Strauss signed the following rule on December 15, 2016

and EPA is submitting it for publication in the Federal Register (FR). While we have taken steps to ensure 

the accuracy of this version of this rule, it is not the official version. Please refer to the official version in a 

forthcoming FR publication appearing on the Government Printing Office website, 

https://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR, and on www.regulations.gov in 

Docket Number EPA-R09-OAR-2016-0287.

6560-50-P

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R09-OAR-2016-0287; FRL-]

Approval of Arizona Air Plan Revisions; Ajo and Morenci, Arizona; Second 10-

Year Sulfur Dioxide Maintenance Plans and Technical Correction

AGENCY: Environmental Protection Agency (EPA). 

ACTION: Direct final rule and technical correction. 

SUMMARY: The Environmental Protection Agency (EPA) is approving the second 10-

year maintenance plans for the Ajo and Morenci areas in Arizona for the 1971 National 

Ambient Air Quality Standards (NAAQS or “standards”) for sulfur dioxide (SO2), and 

correcting an error in the description of the Ajo SO2 maintenance area in the Code of 

Federal Regulations. Elsewhere in this Federal Register, we are proposing approval and 

soliciting written comment on these actions. If we receive adverse comments on this 

direct final rule, resulting in withdrawal of the entire rule or any part(s) of it, we will 

address those comments when we finalize the proposal. The EPA does not plan to 

institute a second comment period on this action. Any parties interested in commenting 

must do so at this time.

DATES: This rule is effective [insert date 60 days from date of publication in Federal 

Register], without further notice, unless we receive adverse comments by [insert date 30 

days from date of publication in Federal Register]. If the EPA receives adverse 

comments, we will publish a timely withdrawal in the Federal Register to notify the 

public that some or all of the provisions in this direct final rule will not take effect. 
This document is a prepublication version signed by Acting EPA Regional Administrator Alexis Strauss on

December 15, 2016. We have taken steps to ensure the accuracy of this version, but it is not the official 

version. 

2

ADDRESSES: Submit your comments, identified by Docket ID No. EPA–R09–OAR–

2016–0287 at http://www.regulations.gov, or via email to Wienke Tax, Air Planning 

Office at tax.wienke@epa.gov. 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 (audio, 

video, etc.) 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 http://www2.epa.gov/dockets/commenting-epadockets. 

You may inspect and copy the rulemaking docket for this notice at the following 

location during normal business hours: Environmental Protection Agency, Region IX, Air 

Division, Air Planning Office (AIR-2), 75 Hawthorne Street, San Francisco, CA 94105-

3901. Copies of the State Implementation Plan materials are also available for inspection 

at the address listed here: Arizona Department of Environmental Quality, 1110 W. 

Washington Street, First Floor, Phoenix, AZ 85007, Phone: (602) 771-4335. 
This document is a prepublication version signed by Acting EPA Regional Administrator Alexis Strauss on

December 15, 2016. We have taken steps to ensure the accuracy of this version, but it is not the official 

version. 

3

FOR FURTHER INFORMATION CONTACT: Wienke Tax, EPA Region IX, (415) 

947-4192, tax.wienke@epa.gov. 

SUPPLEMENTARY INFORMATION: Elsewhere in this Federal Register, we are 

proposing approval and soliciting written comment on this action. Throughout this 

document, the words “we,” “us,” or “our” mean EPA. 

Table of Contents 

I. Summary of Action 

II. Background

A. What National Ambient Air Quality Standards Are Considered in Today's 

Rulemaking? 

B. What Is a State Implementation Plan? 

C. What Is the Background for This Action? 

D. What Are the Applicable Provisions for Second 10-Year Maintenance Plans for 

SO2?

III. The EPA’s Evaluation of the Arizona State Submittals 

A. Did the State Meet the CAA Procedural Requirements?

B. Has the State Met the Substantive Maintenance Plan Provisions? 

IV. Technical Correction

A. History of the Ajo Nonattainment and Maintenance Area Boundary

V. Final Action 

VI. Statutory and Executive Order Reviews 
This document is a prepublication version signed by Acting EPA Regional Administrator Alexis Strauss on

December 15, 2016. We have taken steps to ensure the accuracy of this version, but it is not the official 

version. 

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I. Summary of Action 

We are approving the second 10-year maintenance plans for the Ajo and Morenci, 

Arizona SO2 maintenance areas and correcting an error in the boundary description of the 

Ajo maintenance area in the Code of Federal Regulations (CFR).

1,2

II. Background 

A. What National Ambient Air Quality Standards Are Considered in Today's 

Rulemaking? 

Sulfur dioxide (SO2) is the pollutant that is the subject of this action. The NAAQS 

are health-based and welfare-based standards for certain ambient air pollutants. SO2 is 

among the ambient air pollutants for which we have established a health-based standard.

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 has a variety 

of additional impacts, including acidic deposition, damage to crops and vegetation, and 

corrosion of natural and man-made materials.

 

1

For the definition of the Ajo maintenance area, see 40 CFR 81.303. Ajo is a town located in northwestern 

Pima County, in the southwestern portion of Arizona. The EPA designated the entire area of Pima County 

as nonattainment for SO2 on March 3, 1978 for lack of a State recommendation. The EPA approved the 

State's request that the SO2-affected portion of Pima County be limited to the townships surrounding Ajo 

on April 10, 1979 (44 FR 21261). Townships T11S, R6W; T11S, R5W; T12S, R6W; T12S, R5W; and 

T13S, R6W comprised the nonattainment area. Townships T11S, R7W; T12S, R7W; T13S, R5W; and 

T13S, R7W were designated as “cannot be classified.” At the time of our redesignation, we incorrectly 

identified the maintenance area as all townships and ranges T11S-13S, R5W-R6W as “better than national 

standards.” However, T11S, R7W; T12S, R7W; T13S, R7W; and T13S, R5W were originally designated 

as “cannot be classified” and should have remained such. Today, we are correcting that error.

2

For the definition of the Morenci maintenance area, see 40 CFR 81.303. Morenci is a town in eastern 

Greenlee County near the border of Arizona and New Mexico. The EPA designated the entire area of 

Greenlee County as nonattainment for SO2 on March 3, 1978 for lack of a State recommendation. The EPA 

approved the State’s request that the SO2-affected portion of Greenlee County be limited to the townships 

surrounding Morenci on April 10, 1979 (44 FR 21261). Within Greenlee County, Townships T3S, R28E; 

T3S, R29E; T3S, R30E; T4S, R28E; T4S, R29E; T4S, R30E; T5S, R28E; and T5S, R29E comprise the 

maintenance area. Township T5S, R30E is designated as “cannot be classified.” 
This document is a prepublication version signed by Acting EPA Regional Administrator Alexis Strauss on

December 15, 2016. We have taken steps to ensure the accuracy of this version, but it is not the official 

version. 

5

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.3See 40 CFR 50.4. 

In 2010, the EPA revised the primary SO2 NAAQS by establishing a new 1-hour 

standard of 75 parts per billion (ppb). The EPA revoked the existing 1971 primary 

standards at that time because they would not provide additional public health protection. 

See 75 FR 35550 (June 22, 2010). Today’s action relates only to the revoked 1971 

NAAQS. The State has requested that we take action on these maintenance plans.4

B. What Is a State Implementation Plan? 

The Clean Air Act (CAA or “Act”) requires states to attain and maintain ambient 

air quality equal to or better than the NAAQS. The state's commitments for attaining and 

maintaining the NAAQS are outlined in the State Implementation Plan (SIP) for that 

state. The SIP is a planning document that, when implemented, is designed to ensure the 

achievement of the NAAQS. The Act requires that SIP revisions be made periodically as 

necessary to provide continued compliance with the standards. 

SIPs include, among other things, the following: (1) an inventory of emission 

sources; (2) statutes and regulations adopted by the state legislature and executive 

agencies; (3) air quality analyses that include demonstrations that adequate controls are in 

 

3 Secondary NAAQS are promulgated to protect welfare. The secondary 1971 SO2 NAAQS (3-hour) of 

0.50 ppm is not to be exceeded more than once per year. The Ajo and Morenci areas are not classified 

nonattainment for the secondary standard, and this action relates only to the primary 1971 SO2 NAAQS.

4 This action is consistent with the CAA's anti-backsliding provisions. EPA’s proposed rule on revocation 

of the 1971 SO2 NAAQS discussed that maintenance SIPs would continue being implemented by states 

until such time as they are subsumed by new planning and control requirements associated with the revised 

NAAQS. See 74 FR 64810, 64863 (December 8, 2009). 
This document is a prepublication version signed by Acting EPA Regional Administrator Alexis Strauss on

December 15, 2016. We have taken steps to ensure the accuracy of this version, but it is not the official 

version. 

6

place to meet the NAAQS; and (4) contingency measures to be undertaken if an area fails

to attain the standard or make reasonable progress toward attainment by the required date, 

or a contingency plan if the area fails to maintain the NAAQS once redesignated. The 

state must make the SIP available for public review and comment through a public 

hearing and the SIP must be adopted by the state and submitted to us by the governor or 

her/his designee. 

The EPA takes action on the SIP submittal, thus rendering the rules and 

regulations federally enforceable. The approved SIP serves as the state's commitment to 

take actions that will reduce or eliminate air quality problems. Any subsequent revisions 

to the SIP must go through the formal SIP revision process specified in the Act. 

C. What Is the Background for This Action? 

1. When Were the Nonattainment Areas Established? 

Ajo 

Ajo is located in northwestern Pima County. On March 3, 1978, at 43 FR 8968, 

for lack of a State recommendation, we designated Pima County as a primary SO2

nonattainment area based on monitored violations of the primary SO2 NAAQS in the area 

between 1975 and 1977. At the request of the Arizona Department of Environmental 

Quality (ADEQ), the nonattainment area was subsequently reduced to five townships in 

and around Ajo. See 44 FR 21261 (April 10, 1979). As a result, townships T11S, R6W; 

T11S, R5W; T12S, R6W; T12s, R5W; and T13S, R6W made up the nonattainment area. 

Townships T11S, R7W; T12S, R7W; T13S, R7W; and T13S, R5W were classified as 

“cannot be classified” areas. 

Morenci
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December 15, 2016. We have taken steps to ensure the accuracy of this version, but it is not the official 

version. 

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Morenci is a town in eastern Greenlee County near the border of Arizona and 

New Mexico. On March 3, 1978, at 43 FR 8968, for lack of a state recommendation, we 

designated Greenlee County as a primary SO2 nonattainment area based on monitored 

violations of the primary SO2 NAAQS in the area between 1975 and 1977. At the request 

of the ADEQ, the nonattainment area was subsequently reduced to the townships in and

around Morenci. See 44 FR 21261 (April 10, 1979). As a result, within Greenlee County 

townships T3S, R28E; T3S, R29E; T3S, R30E; T4S, R28E; T4S, R29E; T4S, R30E; 

T5S, R28E; and T5S, R29E made up the nonattainment area. Township T5S, R30E was

classified as a “cannot be classified” area.

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 Ajo and Morenci areas remained nonattainment for the primary SO2 NAAQS 

following enactment of the 1990 CAA Amendments on November 15, 1990. 

2. When Were the Ajo and Morenci Areas Redesignated for SO2?

In 2004, we redesignated the Ajo and Morenci areas under the criteria used for 

areas with shut-down smelters and discontinued monitoring described in a memorandum 

from John Seitz to Regional Office Air Division Directors titled “Redesignation of Sulfur 

Dioxide Nonattainment Areas in the Absence of Monitored Data,” dated October 18, 

2000 (“Seitz Memo”).5

Ajo

 

5 See 68 FR 62239 (November 3, 2003) for Ajo and 69 FR 22447 (April 26, 2004) for Morenci.
This document is a prepublication version signed by Acting EPA Regional Administrator Alexis Strauss on

December 15, 2016. We have taken steps to ensure the accuracy of this version, but it is not the official 

version. 

8

Phelps Dodge Mining Company's Ajo Incorporated (PDAI) operation was the 

largest point source in the Ajo SO2 nonattainment area. On April 4, 1985, the PDAI 

smelter was permanently deactivated. Dismantling of the Ajo facility began in 1995. By 

February 1996, the facility was completely dismantled. On October 15, 1997, ADEQ 

confirmed that the facility was dismantled and no longer existed at the former site. On 

November 3, 2003, the EPA finalized approval of the maintenance plan and redesignation 

request for the Ajo area, effective January 2, 2004 (see 68 FR 62239). At that time, we 

incorrectly identified the maintenance area as townships and ranges T11S-T13S, R5WR6W as “better than national standards.” However, T13S, R5W was originally designated 

as “cannot be classified” and should have remained such. Additionally, townships T13S, 

R5W; T11S, R7W; T12S, R7W; and T13S, R7W were dropped from the CFR, and 

should be listed in 40 CFR part 81.303 as “cannot be classified,” as they were upon Ajo’s 

original designation in 1979. Today, we are correcting those errors.

Morenci

The Phelps Dodge Morenci Incorporated (PDMI) operation was the largest SO2

point source in the Morenci nonattainment area during its operation. PDMI was located 

next to the Morenci copper mine, one of the largest copper producing operations in North 

America. PDMI was located close to the community of Morenci, in eastern Greenlee

County, near the Arizona/New Mexico border.

On December 31, 1984, the PDMI smelter was permanently deactivated. 

Dismantling of the Morenci facility began in 1995 and was complete by December 1996. 

On October 29, 1997, ADEQ confirmed that the facility was dismantled and no longer 

existed at the former site. On April 26, 2004, the EPA finalized approval of the 
This document is a prepublication version signed by Acting EPA Regional Administrator Alexis Strauss on

December 15, 2016. We have taken steps to ensure the accuracy of this version, but it is not the official 

version. 

9

maintenance plan and redesignation request for the Morenci area, effective June 25, 2004 

(see 69 FR 22447). 

3. What is the Current Status of the Areas?

The Ajo and Morenci areas remain sparsely settled, and only minor industrial or 

commercial activities that produce small quantities of SO2 emissions are located in or 

near the nonattainment areas. 

Ajo

In Ajo, the only remaining SO2 point sources consist of emergency generators run 

by Freeport-McMoRan Corporation and Minerals Research and Recovery, which have a 

potential to emit (PTE) of 0.374 tons per year (tpy) of SO2.

6 The 50 kilometer (km) buffer 

area required to be evaluated by the Seitz Memo includes an Arizona Public Service 

emergency generator, a paper mill, the Gila Bend Air Force Auxiliary Field, and a cotton 

gin, with a combined PTE of 7.388 tpy.

7

Currently, no ambient SO2 monitors operate in the Ajo area. However, we do not 

expect the cumulative impact of the sources in and around Ajo to cause a violation of the 

NAAQS because the area’s emissions are so low. No significant new sources have

located in the area since our redesignation of the area to attainment in 2003. 

Morenci

Minor industrial or commercial activities such as Freeport-McMoRan mining 

operations and emergency generators for the Morenci wastewater treatment plant operate 

in the area. The 50 km area around the nonattainment area also contains a construction 

 

6 Final Arizona State Implementation Plan Revision, Maintenance Plan for the Ajo Sulfur Dioxide Planning 

Area (1971 NAAQS) (2013 Ajo Maintenance Plan), page (p.) 23, Table 4.6.

7 2013 Ajo Maintenance Plan, p. 24, Table 4.7.
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company, well fields, and several other sources that all still have active permits and 

together produce about 135 tpy of SO2 emissions.8

Currently, no ambient SO2 monitors operate in the Morenci area. However, we do 

not expect the cumulative impact of the sources in and around Morenci to cause a 

violation of the NAAQS. No significant new sources have located in the area, and the 

smelter was the cause of past violations. 

D. 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 as may be 

necessary to ensure such maintenance. In addition, maintenance plans are to contain such 

contingency provisions as we deem 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 ten years after the expiration of the first 10-year maintenance plan. Beyond these 

provisions, however, section 175A of the CAA does not define the content of a second 

10-year maintenance plan. 

 

8 Proposed Arizona State Implementation Plan Revision, Maintenance Plan for the Morenci Sulfur Dioxide 

Planning Area (1971 NAAQS), p. 20, active permits only.
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2. What General EPA Guidance Applies to SO2 Maintenance Plans? 

Our primary general guidance on maintenance plans and redesignation requests is 

a September 4, 1992 memo from John Calcagni, titled “Procedures for Processing 

Requests to Redesignate Areas to Attainment” (“Calcagni Memo”). Specific guidance on 

SO2 redesignations also appears in a January 26, 1995 memo from Sally L. Shaver, titled 

“Attainment Determination Policy for Sulfur Dioxide Nonattainment Areas” (“Shaver 

Memo”). 

Guidance on SO2 maintenance plan requirements for an area lacking monitored 

ambient data, if the area's historic violations were caused by a major point source that is 

no longer in operation, is found in the Seitz Memo at section II.C.2 and footnote 4. 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 necessary 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, if 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 
This document is a prepublication version signed by Acting EPA Regional Administrator Alexis Strauss on

December 15, 2016. We have taken steps to ensure the accuracy of this version, but it is not the official 

version. 

12

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 10th year after redesignation; all three 

inventories should include estimates of emissions in a 50 km buffer zone around the 

nonattainment area;

(2) dispersion modeling showing that no NAAQS violations will occur over the 

next 10 years and that the shut-down source was the dominant cause of the high 

concentrations in the past; 

(3) evidence that if the shut-down 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. 

III. The EPA’s Evaluation of Arizona’s Submittals Addressing These Provisions 

A. Did the State Meet the CAA Procedural Requirements? 

Ajo 

On February 22, 2013, ADEQ submitted to the EPA the “Final Arizona State 

Implementation Plan Revision, Maintenance Plan for the Ajo Sulfur Dioxide Planning 

Area (1971 NAAQS)” (“2013 Ajo Maintenance Plan”). The State verified that it had 

adhered to its SIP adoption procedures in Appendix E to the 2013 Ajo Maintenance Plan, 

which includes the notice of public hearing, the agenda for the February 7, 2013 public 
This document is a prepublication version signed by Acting EPA Regional Administrator Alexis Strauss on

December 15, 2016. We have taken steps to ensure the accuracy of this version, but it is not the official 

version. 

13

hearing, the sign in sheet, the public hearing officer certification and transcript of the 

hearing, and the State’s responsiveness summary.

On August 22, 2013, the 2013 Ajo 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 EPA formal review. 

Morenci

On December 18, 2014, ADEQ submitted to the EPA the “Proposed Arizona 

State Implementation Plan Revision, Maintenance Plan for the Morenci Sulfur Dioxide 

Planning Area (1971 NAAQS)” (“2014 Morenci Maintenance Plan”). The State verified 

that it had adhered to its SIP adoption procedures in Appendix E to the 2014 Morenci 

Maintenance Plan, which includes the notice of public hearing, the agenda for the 

December 15, 2014 public hearing, the sign in sheet, the public hearing officer 

certification and transcript of the hearing, and the State’s responsiveness summary.

On May 10, 2015, the 2014 Morenci 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 EPA formal review. 

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 Ajo 

nonattainment area was the Phelps Dodge Mining Company's PDAI copper smelter, 

which ceased operation in 1985 and was completely dismantled by February 1996. The 

last recorded 24-hour or annual average exceedances of the primary NAAQS at PDAI 
This document is a prepublication version signed by Acting EPA Regional Administrator Alexis Strauss on

December 15, 2016. We have taken steps to ensure the accuracy of this version, but it is not the official 

version. 

14

occurred in 1984. During the monitoring network's history, annual average SO2 levels 

were generally half of the current NAAQS (0.030 ppm). See 2013 Ajo Maintenance Plan, 

page (p.) 17. ADEQ removed the SO2 monitor in 1985, and the smelter operating permits 

expired. The smelting equipment was removed over a period of years, and the smelter 

was completely dismantled by February 1996. No new sources of SO2 of the magnitude 

of PDAI have located in the area. Thus, Ajo meets this criterion for review under the 

Seitz Memo. 

As discussed above, the only major source of SO2 emissions within the Morenci

nonattainment area was the Phelps Dodge Mining Company's PDMI copper smelter, 

which was permanently deactivated by December 31, 1984 and was completely 

dismantled by December 1996. The last recorded 24-hour or annual average exceedances 

of the primary NAAQS at PDMI occurred in 1984. During the monitoring network's 

history, annual average SO2 levels were generally half of the current NAAQS (0.030 

ppm). See 2014 Morenci Maintenance Plan, p. 15-16. ADEQ removed the SO2 monitors

in 1985, and the smelter operating permits expired. The smelting equipment was removed 

over a period of years, and the smelter was completely dismantled by December 1996. 

No new sources of SO2 of the magnitude of PDMI have located in the area. Thus, 

Morenci meets this criterion for review under the Seitz Memo.

2. Has the State Met the Requirements for Second 10-Year Maintenance Plans? 

The 2013 Ajo Maintenance Plan and 2014 Morenci Maintenance Plan both 

extend the maintenance period for ten years after the expiration of the first 10-year 

maintenance plans, 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, 
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version. 

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modeling, permitting of major new sources, and agreement to commence monitoring if a 

new major source locates in either the Ajo or Morenci areas. Therefore, the State has met 

the specific criteria in the Seitz Memo for approval of maintenance plans and 

redesignation requests where a single source was the historic cause of violations and the 

source is now shut down. We provide more details on each requirement and how the 

2013 Ajo Maintenance Plan and the 2014 Morenci Maintenance Plan meet each

requirement in the following sections.

Ajo

a. Emissions Inventories

In addition to reproducing the emissions inventories in the Ajo Sulfur Dioxide 

Nonattainment Area State Implementation Plan and Maintenance Plan (June 18, 2002) 

(“2002 Ajo maintenance plan”), the 2013 Ajo Maintenance Plan includes new emissions 

inventories for 2008, representing an updated “current” emissions inventory (the most 

recent National Emissions Inventory (NEI) available at the time), 2010, 2015, 2020, and 

2025 for the second 10-year maintenance period.9 Continued maintenance of the Ajo area 

for 10 years following the initial 10-year maintenance period is demonstrated in part by 

showing that future SO2 emissions in the area are not expected to exceed the level of the 

attainment emissions inventory. 

The emissions inventories in the 2013 Ajo Maintenance Plan include estimates of 

SO2 from all relevant source categories, which the 2013 Plan divides among stationary, 

 

9 The State provided the three emissions inventories specified in the Seitz Memo for the sources in, and 

within 50 kilometers of, the Ajo nonattainment area in the 2002 Ajo maintenance plan. For a representative 

year when the copper smelter was in operation (1981), direct SO2 emissions from smelting operations were 

39,596 tpy. ADEQ’s 2002 submittal identified only a single existing point source within the Ajo Area, the 

Phelps Dodge Generator Station. Phelps Dodge has since shut down the generators and no longer uses them 

as emergency/back up electric supply. See 2013 Ajo Maintenance Plan, p. 32 and Appendix C-1.
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and area and mobile. Point source information was received from the Pima County 

Department of Environmental Quality (PDEQ) and the Maricopa County Air Quality 

Division’s annual emissions inventory data. The Ajo maintenance area contains two point 

sources (i.e., Freeport-McMoRan Corporation Childs Well Field Emergency Generator, 

and Minerals Research and Recovery, Inc.), which together emit less than 1 tpy SO2. The 

50 km buffer area contains four point sources, including a cotton gin, a paper mill, an Air 

Force auxiliary field, and an emergency generator. The 2013 Ajo Maintenance Plan

includes a description of current facility types, emitting equipment, permitted emissions 

limits, operating rates, and emissions calculation methods.

Area and mobile sources in ADEQ’s 2008 and subsequent year inventories were 

derived from the EPA’s NEI and local agency records. Historical and 2008 emissions 

inventories demonstrate that no significant area or mobile sources existed in the Ajo area 

prior to or subsequent to the smelter operation, which closed in 1985. 

Based on our review of the emissions inventories in the 2013 Ajo Maintenance 

Plan and the supporting information in Appendix C, 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 all 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 conservatively show that non-smelter 

sources have only an insignificant contribution to average SO2 concentrations in a 

nonattainment area. 
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17

For the 2002 Ajo Maintenance Plan, screening dispersion modeling was 

performed using the SCREEN3 model run with conservative assumptions about source 

parameters and meteorology. At the time of the 2002 Ajo Maintenance Plan, the Ajo 

nonattainment area had one minor point source of SO2 emissions (i.e., Phelps-Dodge 

Generating Station) and one permitted minor point source in the 50 km buffer (i.e., the 

proposed Gila Bend Regional Landfill). The model predicted that the impact from these 

two sources would not exceed 66% of the 1971 SO2 NAAQS, even assuming constant 

worst-case conditions about high-sulfur content fuel use.

The Seitz Memo also requires a modeling analysis that shows that the point 

sources that were shutdown 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 emission controls were placed on the smelter, 

this same screening modeling was used to show that the non-smelter sources were 

insignificant in the past, and thus the smelter was the dominant source contributing to 

past high SO2 concentrations. 

ADEQ did not conduct a new modeling analysis for the 2013 Ajo Maintenance 

Plan. As described above, the modeling for the 2002 Ajo Maintenance Plan modeled the 

existing two sources at maximum projected emissions rates from 2004 to 2015 and 

showed the area would not exceed 66% of the NAAQS. Since that modeling analysis was 

conducted, the Phelps-Dodge Generating Station has shut down, the Gila Bend Regional 

Landfill was never constructed, and the permit for the landfill was allowed to expire. 

Currently, only two sources operate within the nonattainment area (i.e., FreeportMcMoRan Incorporated Childs Well Field Emergency Generator, and Minerals Research 
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18

and Recovery), and they are permitted to emit less than 1% of the emissions modeled in 

the 2002 Ajo Maintenance Plan. Point sources within the 50 km buffer surrounding the 

nonattainment area emit about 25% of emissions modeled in the 2002 Ajo Maintenance 

Plan. 2025 projections show that these low emissions are expected to persist through the 

second 10-year maintenance period. See 2013 Ajo Maintenance Plan, pp. 33 and 34.

ADEQ proposes, and we concur, that because current emissions in the 

maintenance area and the 50 km buffer are a small fraction of modeled emissions from 

2002, the ambient SO2 modeling requirement for second 10-year maintenance plans is 

met by the prior modeling, and the State has demonstrated that the 1971 SO2 NAAQS is 

adequately protected.

c. Treatment of New Sources of SO2 Emissions

In nonattainment areas, section 172(c)(5) of the CAA requires New Source 

Review (NSR) permits prior to the construction and operation of new major stationary 

sources and major modifications at existing major stationary sources. However, in 

attainment areas, section 165 of the CAA requires major sources and major modifications 

to obtain PSD permits. The PSD program requires stationary sources to apply the best 

available control technology and ensure that projects will not cause or contribute to a 

violation of a NAAQS or maximum allowable increase.

ADEQ and the PDEQ have PSD permitting programs (i.e., Arizona 

Administrative Code (A.A.C.) R18-2-406 and Pima County Code 17.16.590) that were 

established to preserve the air quality in areas where ambient standards have been met. 

The State's updated PSD program was approved into the SIP on November 2, 2015 (80 
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FR 67319). PDEQ's PSD program is not SIP-approved, but the federal PSD permitting 

program at 40 CFR 52.21 was delegated to PDEQ effective April 14, 1994.

The PSD program has applied to any major source or major modification in the 

Ajo area since the area was redesignated to attainment for SO2 in 2003, except for coarse 

particulate (PM10), for which the area is designated nonattainment. Under section 

172(c)(5) of the CAA, major sources and major modifications of PM10 in the Ajo area 

remain subject to the nonattainment NSR program, while all other NSR regulated 

pollutants are subject to the PSD program. Thus the existing ADEQ and PDEQ PSD and

NSR programs satisfy the preconstruction permit provision of the Seitz Memo as one of 

the prerequisites to redesignation for the Ajo SO2 nonattainment area.

d. Commitment to Resume Monitoring

ADEQ commits to resume monitoring before any major source of SO2

commences to operate in the Ajo maintenance area. See 2013 Ajo Maintenance Plan, p. 

38. This addresses the monitoring provision of the Seitz Memo. 

Morenci

a. Emissions Inventory

The 2014 Morenci Maintenance Plan includes historical inventories that were 

submitted as part of the Morenci Sulfur Dioxide Nonattainment Area State 

Implementation Plan and Maintenance Plan (submitted June 21, 2002) (“2002 Morenci 

maintenance plan”) as well as a current-year inventory for 2011 (the most recent NEI 

available at the time), and projected inventories for 2015, 2020, 2025, and 2030 for the 

second 10-year maintenance period.

10

 

10 In the 2002 Morenci Maintenance Plan, the State provided the three emissions inventories specified in 

the Seitz Memo for the sources in, and within 50 kilometers of, the Morenci nonattainment area. For a 
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The emissions inventories in the 2014 Morenci Maintenance Plan include 

estimates of SO2 emissions from all relevant source categories, which are divided among 

stationary, area, and mobile source categories. Additional information on how the 

inventories were developed, including activity data and emissions calculations, is 

provided in Appendix C of the 2014 Morenci Maintenance Plan. Point source 

information was developed by ADEQ from permit information and the NEI. The 2011 

inventory identifies two existing point sources within the Morenci maintenance area: the 

Freeport-McMoRan Morenci mine with 2011 actual emissions of 48.5 tpy SO2, and the 

Morenci Townsite Wastewater Treatment Plant Emergency Generators with 2011 actual 

emissions of 0.003 tpy SO2. In 2011, 13 point additional sources with actual emissions of 

38.05 tpy SO2 were located within 50 km of the Morenci maintenance area boundary. As 

of 2014, six of these sources had terminated their permits, resulting in slightly lower 

emissions. 

Area and mobile source emissions in ADEQ’s 2011 and subsequent year 

inventories were derived from the NEI. The year 2011 was a historically high wildfire 

year, and included the largest wildfire in Arizona history (i.e., the Wallow fire), which 

burned in Greenlee County and surrounding areas.

11 ADEQ assumed the 2011 wildfire 

emissions remained constant when projecting emissions into the future. 

 

representative year when the copper smelter was in operation (1984), direct actual SO2 emissions from 

smelting operations were 82,432 tpy. During its operation, the Morenci primary copper smelter was the 

only major point source in the area. The 2002 Morenci Maintenance Plan included inventories for 1984 (a 

year the smelter was in operation), 1999 (a year the area was attaining the SO2 standard), and 2015 (the 

projected inventory for the horizon year of the maintenance period). Sources in the 50 km buffer around the 

Morenci area were estimated to emit 186.5 tpy in 1999, based on PTE, but had actual emissions 

significantly lower, at 1.2 tpy. See 2014 Morenci Maintenance Plan, p. 18.

11 National Interagency Fire Center’s website at https://www.nifc.gov/fireInfo/fireInfo_statistics.html, 

“Historical year-end statistics by state,” and https://en.wikipedia.org/wiki/List_of_Arizona_wildfires. Acres 
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Based on our review of the emissions inventories in the 2014 Morenci 

Maintenance Plan and the supporting information in Appendix C, we conclude that the 

inventories are complete, accurate, and consistent with applicable CAA provisions and 

the Seitz Memo. 

b. Dispersion Modeling

The 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. For the 2002 Morenci Maintenance Plan, screening dispersion modeling 

was performed using the SCREEN3 model, which was run with conservative 

assumptions about source parameters and meteorology. The modeling results indicated 

that the impact of existing sources on concentrations within the nonattainment area would 

not exceed 25 percent of the 1971 SO2 NAAQS. 

The Seitz Memo also requires a modeling analysis that shows point sources that 

were shutdown were the dominant sources contributing to high SO2 concentrations in the 

airshed. The screening modeling described above was used in the 2002 Morenci 

Maintenance Plan to show that the non-smelter sources have an insignificant 

contribution, and thus the smelter was the dominant source contributing to past high SO2

concentrations. 

For the 2014 Morenci Maintenance Plan, ADEQ conducted a modeling analysis 

similar to the analysis in the 2002 Morenci Maintenance Plan. The two largest sources in 

the maintenance area and within the 50 km buffer area were modeled. The two sources 

 

burned in 2011 in Arizona were more than 10 times higher than 2010 acres burned in Arizona due to 

wildfires, and about five times higher than acres burned in Arizona in 2012 due to wildfires. 
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are Freeport-McMoRan Morenci Mine (FMMM) in the maintenance area, with a PTE of 

88 tpy SO2, and the Freeport-McMoRan Safford Mine (FMSM) in the 50 km buffer area, 

with a PTE of 81 tpy SO2. Other point sources were not modeled because of their small 

or negligible emissions. 

The EPA dispersion model AERSCREEN (version 11126) was used to 

conservatively estimate the impact of FMMM and FMSM on maintenance in the Morenci 

planning area.12 The results of the AERSCREEN modeling indicated that the impact of 

these existing sources would have a cumulative potential impact of 42-53% of the 1971 

annual and 24-hour SO2 NAAQS respectively. See 2014 Morenci Maintenance Plan, p. 

29. Projections for 2030 show that this low level of emissions is expected to persist 

through the second maintenance period. See 2014 Morenci Maintenance Plan, p. 32. We 

therefore conclude that the State has demonstrated that the 1971 SO2 NAAQS is 

adequately protected.

c. Treatment of New Sources of SO2 Emissions

In nonattainment areas, section 172(c)(5) of the CAA requires NSR permits prior 

to the construction and operation of new major stationary sources and major 

modifications at existing major stationary sources. However, in attainment areas, section 

165 of the CAA requires major sources and major modifications to obtain PSD permits. 

The PSD program requires stationary sources to apply the best available control 

 

12 AERSCREEN has replaced SCREEN3 as the EPA’s preferred screening model. See Memorandum dated 

April 11, 2011, from Tyler Fox to the EPA Regional Modeling Contacts, “AERSCREEN Released as EPA 

Recommended Screening Model” in the docket for today’s action. SCREEN3 was used for the 2002 

Morenci Maintenance Plan.
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technology and ensure projects will not cause or contribute to a violation of a NAAQS or 

maximum allowable increase.

ADEQ has a PSD permitting program (i.e., A.A.C. R18-2-406) that was

established to preserve the air quality in areas where ambient standards have been met. 

The State's updated PSD program was approved into the SIP on November 2, 2015 (80 

FR 67319). The PSD program has applied to any major source or major modification in 

the Morenci area since the area was redesignated to attainment for SO2 in 2004. Thus the 

ADEQ’s existing PSD program satisfies the preconstruction permit provision of the Seitz 

Memo as one of the prerequisites to redesignation for the Morenci SO2 nonattainment 

area.

d. Commitment to Resume Monitoring 

ADEQ commits to resume monitoring before any major source of SO2

commences to operate. See 2014 Morenci Maintenance Plan, p. 16. This addresses 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. 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 standard 

which occurs after the redesignation of the area as an attainment area. 
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Ajo 

The 2013 Ajo Maintenance Plan includes the State's commitment to continue to 

track maintenance of the SO2 NAAQS through updates to the emissions inventory. 

Additionally, ADEQ commits to reestablish an appropriate air quality monitoring 

network before any major source of SO2 begins operations in the Ajo maintenance area. 

See 2013 Ajo Maintenance Plan, p. 38. 

Since the primary cause of future violations of the 1971 SO2 NAAQS in the area 

would be from modified or new point sources, ADEQ's current operating permit program 

places limits on SO2 emissions from existing sources. Should a new facility be 

constructed in the Ajo area or an existing facility want to upgrade or increase SO2 

emissions, the facility would also be subject to PSD as required in the Calcagni Memo. 

The Calcagni Memo emphasizes the importance of specific contingency 

measures, schedules for adoption, and action levels to trigger implementation of the 

contingency plan. Since there are no remaining sources of SO2 emissions of the 

magnitude of the PDAI smelter, and there is no SO2 monitoring in the Ajo area, we agree 

with the State that the level of specificity recommended in the Calcagni Memo is not 

necessary, and we conclude that the State's commitment satisfactorily addresses the CAA 

provisions. We find that the State’s commitment to continue to track maintenance of the 

SO2 NAAQS through updates to the emissions inventory and the State's PSD permitting 

programs are sufficient to assure that the Ajo area will not violate the NAAQS.

Morenci

The 2014 Morenci Maintenance Plan includes the State's commitment to continue 

to demonstrate maintenance of the SO2 NAAQS through updates to the emissions 
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inventory. Additionally, ADEQ commits to reestablish an appropriate air quality 

monitoring network before any major source of SO2 begins operations in the Morenci 

maintenance area. See 2014 Morenci Maintenance Plan, p. 32. 

Since the primary cause of future violations of the 1971 SO2 NAAQS in the area 

would be from modified or new point sources, ADEQ's current operating permit program 

places limits on SO2 emissions from existing sources. Should a new facility be 

constructed in the Morenci area or an existing facility want to upgrade or increase SO2 

emissions, the facility would also be subject to PSD as required in the Calcagni Memo. 

The Calcagni Memo emphasizes the importance of specific contingency 

measures, schedules for adoption, and action levels to trigger implementation of the 

contingency plan. Since there are no remaining sources of SO2 emissions of the 

magnitude of the PDMI smelter, and there is no SO2 monitoring in the Morenci area, we 

agree with the State that the level of specificity recommended in the Calcagni Memo is 

not necessary, and we conclude that the State's commitment satisfactorily addresses the 

CAA provisions. We find that the State’s commitment to continue to track maintenance 

of the SO2 NAAQS through updates to the emissions inventory and the State's PSD 

permitting programs are sufficient to assure that the Morenci area will not violate the 

NAAQS.

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 
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26

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”) as well as 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,13 only the requirements related to general 

conformity apply to the Ajo and Morenci areas. 

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, as well as public notification of and access to 

federal agency conformity determinations, and allows for air quality review of individual 

federal actions.

Section 176(c) of the CAA required 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. SIP revisions intended to meet the conformity requirements in section 

 

13 40 CFR 93.102(b)(1).
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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. 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 both Ajo and Morenci 

have already been redesignated for this standard, 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 second ten-year maintenance plans. 

Criteria for making determinations and provisions for general conformity are 

contained in Arizona Administrative Code R18-2-1438. Arizona has an approved general 

conformity SIP.14

Ajo

ADEQ commits in the 2013 Ajo 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 this planning area, 

although none are currently planned for the area. See 2013 Ajo Maintenance Plan, p. 13.

 

14 64 FR 19916, April 23, 1999.
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Morenci

ADEQ commits in the 2014 Morenci 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 this planning area, 

although none are currently planned for the area. See 2014 Morenci Maintenance Plan, p. 

11.

IV. Technical Correction

A. History of the Ajo Nonattainment and Maintenance Area Boundary

On November 3, 2003, the EPA finalized approval of the maintenance plan and 

redesignation request for the Ajo area, effective January 2, 2004 (see 68 FR 62239). To 

codify this rulemaking, we amended 40 CFR 81.303 that lists the designations for air 

quality planning areas in Arizona, but we incorrectly identified the Ajo maintenance area 

in the Arizona SO2 table by dropping township T13S, R5W from the maintenance area, 

and inadvertently deleted other townships and ranges in the “cannot be classified”

description. Township T13S, R5W as well as townships T11S, R7W; T12S, R7W; and 

T13S, R7W should have remained “cannot be classified.”

Section 110(k)(6) of the CAA provides that when the EPA’s action approving any 

plan or plan revision (or part thereof), area designation, redesignation, classification, or 

reclassification was in error, the EPA may in the same manner revise such action. Under 

the EPA’s authority under section 110(k)(6) of the Act, we are taking direct final action 

to amend the Arizona-SO2 table in 40 CFR 81.303 by re-codifying and correcting the 

previous detailed descriptions of the Ajo maintenance area and townships identified as 

“cannot be classified.”
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The maintenance area consists of townships T11S, R6W; T11S, R5W; T12S, 

R6W; T12S, R5W; and T13S, R6W. In addition, townships T13S, R5W; T11S, R7W; 

T12S, R7W; and T13S, R7W are listed in 40 CFR part 81.303 as “cannot be classified,” 

as they were upon the Ajo area’s original designation in 1979.

V. Final Action 

We are approving the second 10-year SO2 maintenance plans for the Ajo and 

Morenci areas in Arizona under sections 110 and 175A of the CAA and correcting an 

error made in the description of the Ajo maintenance area and in the identification of 

townships as “cannot be classified” in the CFR when we redesignated the area in 2003. 

As authorized in section 110(k)(3) of the Act, the EPA is fully approving the submitted 

SIPs because we believe they fulfill all relevant requirements. We do not think anyone 

will object to this approval, so we are finalizing it without proposing it in advance. 

However, in the Proposed Rules section of this Federal Register, we are simultaneously 

proposing approval of the same submitted SIPs. If we receive adverse comments by 

[Insert date 30 days after date of publication in the Federal Register], we will publish 

a timely withdrawal in the Federal Register to notify the public that some or all of the 

provisions of the direct final approval will not take effect and we will address the 

comments in a subsequent final action based on the proposal. If we do not receive timely 

adverse comments, the direct final approval will be effective without further notice on 

[Insert date 60 days after date of publication in the Federal Register]. This will 

incorporate these SIPs into the federally enforceable SIP.
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VI. Statutory and Executive Order Reviews 

Under the Clean Air Act, 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 

Clean Air Act. 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); 

• 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 (Public Law 

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); 
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• 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 Clean Air Act; 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. section 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).
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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

[Insert date 60 days after date of publication in the Federal Register]. 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. Parties with objections to this direct final rule are 

encouraged to file a comment in response to the parallel notice of proposed rulemaking 

for this action published in the Proposed Rules section of today’s Federal Register, 

rather than file an immediate petition for judicial review of this direct final rule, so that 

the EPA can withdraw this direct final rule and address the comment in the proposed 

rulemaking. This action may not be challenged later in proceedings to enforce its 

requirements (see section 307(b)(2)).

List of Subjects 

40 CFR Parts 52 and 81 

Environmental protection, Air pollution control, Incorporation by reference, 

Intergovernmental relations, Reporting and recordkeeping requirements, Sulfur dioxide. 

________________ __________________________

Dated: Alexis Strauss,

Acting Regional Administrator, 

EPA Region IX. 
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Chapter I, title 40 of the Code of Federal Regulations is amended as follows:

PART 52 - APPROVAL AND PROMULGATION OF IMPLEMENTATION 

PLANS

1. The authority citation for Part 52 continues to read as follows:

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

Subpart D – Arizona

2. Section 52.120 in paragraph (e), table 1 is amended:

a. By adding an entry for “‘Arizona State Implementation Plan Revision, Maintenance 

Plan for the Ajo Sulfur Dioxide Area (1971 NAAQS), (February 2013) excluding 

Appendix C, “Overview of Point Source Emissions Limits and Potential to Emit” after 

the heading “Plan D Elements and Plans (Other than for the Metropolitan Phoenix and 

Tucson Areas)’”; and 

b. By adding an entry for “Arizona State Implementation Plan Revision, Maintenance 

Plan for the Morenci Sulfur Dioxide Area (1971 NAAQS), (December 2014)” after the 

entry for “Final Miami Sulfur Dioxide Nonattainment Area State Implementation and 

Maintenance Plan (June 2002)(revised May 26, 2004), excluding appendix A (“SIP 

Support Information”), sections A.1 (“Pertinent Sections of the Arizona Administrative 

Code”) and A.2 (“Information Regarding Revisions to AAC R18-2-715 and R18-2-

715.01, ‘Standards of Performance for Primary Copper Smelters: Site Specific 

Requirements; Compliance and Monitoring’”); and appendix D (“SIP Public Hearing 

Documentation”)”.

The additions read as follows:

§ 52.120 Identification of plan.
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* * * * *

(e) * * *

Table 1--EPA-Approved Non-Regulatory and Quasi-Regulatory Measures 

(Excluding certain resolutions and statutes, which are listed in tables 2 and 3, 

respectively)1

Name of SIP 

provision

Applicable 

geographic or 

nonattainment 

area or 

title/subject

State 

submittal 

date

EPA approval 

date Explanation

THE STATE OF ARIZONA AIR POLLUTION CONTROL 

IMPLEMENTATION PLAN

* * * * * *

*

Arizona State 

Implementation 

Plan Revision, 

Maintenance 

Plan for the Ajo 

Sulfur Dioxide 

Area (1971 

NAAQS), 

(February 

2013),

excluding 

Appendix C, 

“Overview of 

Point Source 

Emissions 

Limits and 

Potential to 

Emit”

Ajo Sulfur 

Dioxide Air 

Quality 

Planning Area

February 22, 

2013

[INSERT 

Federal Register

CITATION], 

[INSERT DATE 

OF 

PUBLICATION]

Adopted by the 

Arizona 

Department of 

Environmental 

Quality on 

February 22, 

2013. Fulfills 

requirements 

for second tenyear 

maintenance 

plans. The SIP 

includes a 

request to 

correct the 

maintenance 

area boundary. 

* * * * * *

*

Arizona State 

Implementation 

Plan Revision, 

Maintenance 

Morenci 

Sulfur Dioxide 

Air Quality 

Planning Area

December 

18, 2014

[INSERT 

Federal Register

CITATION], 

[INSERT DATE 

Adopted by the 

Arizona 

Department of 

Environmental 
This document is a prepublication version signed by Acting EPA Regional Administrator Alexis Strauss on

December 15, 2016. We have taken steps to ensure the accuracy of this version, but it is not the official 

version. 

35

Plan for the 

Morenci Sulfur 

Dioxide Area 

(1971 

NAAQS), 

(December 

2014)

OF 

PUBLICATION]

Quality on 

December 18, 

2014. Fulfills 

requirements 

for second tenyear 

maintenance 

plans.

* * * * * *

*

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.

* * * * *

PART 81- DESIGNATION OF AREAS FOR AIR QUALITY PLANNING 

PURPOSES

3. The authority citation for Part 81 continues to read as follows:

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

4. Section 81.303 is amended in the table for “Arizona—1971 Sulfur Dioxide NAAQS 

(Primary and Secondary)” by revising the entry for “Ajo” to read as follows:

§ 81.303 Arizona.

* * * * *

Arizona—1971 Sulfur Dioxide NAAQS (Primary and Secondary)

Designated area

Does not meet 

primary standards

Does not meet 

secondary 

standards

Cannot be 

classified

Better than 

national 

standards

Ajo:

T11S, R5W X
This document is a prepublication version signed by Acting EPA Regional Administrator Alexis Strauss on

December 15, 2016. We have taken steps to ensure the accuracy of this version, but it is not the official 

version. 

36

T11S, R6W X

T12S, R5W X

T12S, R6W X

T13S, R6W X

T11S, R7W X

T12S, R7W X

T13S, R5W X

T13S, R7W X

* * * * * * *

* * * * *