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ENCLOSURE 1

Arizona Revised Statutes §§ 49-104, 49-106, and 49-404
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49-104. Powers and duties of the department and director

A. The department shall:

1. Formulate policies, plans and programs to implement this title to protect the environment.

2. Stimulate and encourage all local, state, regional and federal governmental agencies and all private 

persons and enterprises that have similar and related objectives and purposes, cooperate with those 

agencies, persons and enterprises and correlate department plans, programs and operations with those of 

the agencies, persons and enterprises.

3. Conduct research on its own initiative or at the request of the governor, the legislature or state or local 

agencies pertaining to any department objectives.

4. Provide information and advice on request of any local, state or federal agencies and private persons 

and business enterprises on matters within the scope of the department.

5. Consult with and make recommendations to the governor and the legislature on all matters concerning 

department objectives.

6. Promote and coordinate the management of air resources to assure their protection, enhancement and 

balanced utilization consistent with the environmental policy of this state.

7. Promote and coordinate the protection and enhancement of the quality of water resources consistent 

with the environmental policy of this state.

8. Encourage industrial, commercial, residential and community development that maximizes 

environmental benefits and minimizes the effects of less desirable environmental conditions.

9. Assure the preservation and enhancement of natural beauty and man-made scenic qualities.

10. Provide for the prevention and abatement of all water and air pollution including that related to 

particulates, gases, dust, vapors, noise, radiation, odor, nutrients and heated liquids in accordance with 

article 3 of this chapter and chapters 2 and 3 of this title.

11. Promote and recommend methods for the recovery, recycling and reuse or, if recycling is not possible, 

the disposal of solid wastes consistent with sound health, scenic and environmental quality policies. 

Beginning in 2014, the department shall report annually on its revenues and expenditures relating to the 

solid and hazardous waste programs overseen or administered by the department.

12. Prevent pollution through the regulation of the storage, handling and transportation of solids, liquids 

and gases that may cause or contribute to pollution.

13. Promote the restoration and reclamation of degraded or despoiled areas and natural resources.

14. Assist the department of health services in recruiting and training state, local and district health 

department personnel.
15. Participate in the state civil defense program and develop the necessary organization and facilities to 

meet wartime or other disasters.

16. Cooperate with the Arizona-Mexico commission in the governor's office and with researchers at 

universities in this state to collect data and conduct projects in the United States and Mexico on issues 

that are within the scope of the department's duties and that relate to quality of life, trade and economic 

development in this state in a manner that will help the Arizona-Mexico commission to assess and 

enhance the economic competitiveness of this state and of the Arizona-Mexico region.

17. Unless specifically authorized by the legislature, ensure that state laws, rules, standards, permits, 

variances and orders are adopted and construed to be consistent with and no more stringent than the 

corresponding federal law that addresses the same subject matter. This provision shall not be construed to 

adversely affect standards adopted by an Indian tribe under federal law.

B. The department, through the director, shall:

1. Contract for the services of outside advisers, consultants and aides reasonably necessary or desirable to 

enable the department to adequately perform its duties.

2. Contract and incur obligations reasonably necessary or desirable within the general scope of 

department activities and operations to enable the department to adequately perform its duties.

3. Utilize any medium of communication, publication and exhibition when disseminating information, 

advertising and publicity in any field of its purposes, objectives or duties.

4. Adopt procedural rules that are necessary to implement the authority granted under this title, but that 

are not inconsistent with other provisions of this title.

5. Contract with other agencies, including laboratories, in furthering any department program.

6. Use monies, facilities or services to provide matching contributions under federal or other programs 

that further the objectives and programs of the department.

7. Accept gifts, grants, matching monies or direct payments from public or private agencies or private 

persons and enterprises for department services and publications and to conduct programs that are 

consistent with the general purposes and objectives of this chapter. Monies received pursuant to this 

paragraph shall be deposited in the department fund corresponding to the service, publication or program 

provided.

8. Provide for the examination of any premises if the director has reasonable cause to believe that a 

violation of any environmental law or rule exists or is being committed on the premises. The director shall 

give the owner or operator the opportunity for its representative to accompany the director on an 

examination of those premises. Within forty-five days after the date of the examination, the department 

shall provide to the owner or operator a copy of any report produced as a result of any examination of the 

premises.

9. Supervise sanitary engineering facilities and projects in this state, authority for which is vested in the 

department, and own or lease land on which sanitary engineering facilities are located, and operate the 
facilities, if the director determines that owning, leasing or operating is necessary for the public health, 

safety or welfare.

10. Adopt and enforce rules relating to approving design documents for constructing, improving and 

operating sanitary engineering and other facilities for disposing of solid, liquid or gaseous deleterious 

matter.

11. Define and prescribe reasonably necessary rules regarding the water supply, sewage disposal and 

garbage collection and disposal for subdivisions. The rules shall:

(a) Provide for minimum sanitary facilities to be installed in the subdivision and may require that water 

systems plan for future needs and be of adequate size and capacity to deliver specified minimum 

quantities of drinking water and to treat all sewage.

(b) Provide that the design documents showing or describing the water supply, sewage disposal and 

garbage collection facilities be submitted with a fee to the department for review and that no lots in any 

subdivision be offered for sale before compliance with the standards and rules has been demonstrated by 

approval of the design documents by the department.

12. Prescribe reasonably necessary measures to prevent pollution of water used in public or semipublic 

swimming pools and bathing places and to prevent deleterious conditions at such places. The rules shall 

prescribe minimum standards for the design of and for sanitary conditions at any public or semipublic 

swimming pool or bathing place and provide for abatement as public nuisances of premises and facilities 

that do not comply with the minimum standards. The rules shall be developed in cooperation with the 

director of the department of health services and shall be consistent with the rules adopted by the director 

of the department of health services pursuant to section 36-136, subsection H, paragraph 10.

13. Prescribe reasonable rules regarding sewage collection, treatment, disposal and reclamation systems 

to prevent the transmission of sewage borne or insect borne diseases. The rules shall:

(a) Prescribe minimum standards for the design of sewage collection systems and treatment, disposal and 

reclamation systems and for operating the systems.

(b) Provide for inspecting the premises, systems and installations and for abating as a public nuisance any 

collection system, process, treatment plant, disposal system or reclamation system that does not comply 

with the minimum standards.

(c) Require that design documents for all sewage collection systems, sewage collection system 

extensions, treatment plants, processes, devices, equipment, disposal systems, on-site wastewater 

treatment facilities and reclamation systems be submitted with a fee for review to the department and may 

require that the design documents anticipate and provide for future sewage treatment needs.

(d) Require that construction, reconstruction, installation or initiation of any sewage collection system, 

sewage collection system extension, treatment plant, process, device, equipment, disposal system, on-site 

wastewater treatment facility or reclamation system conform with applicable requirements.

14. Prescribe reasonably necessary rules regarding excreta storage, handling, treatment, transportation and 

disposal. The rules shall:
(a) Prescribe minimum standards for human excreta storage, handling, treatment, transportation and 

disposal and shall provide for inspection of premises, processes and vehicles and for abating as public 

nuisances any premises, processes or vehicles that do not comply with the minimum standards.

(b) Provide that vehicles transporting human excreta from privies, septic tanks, cesspools and other 

treatment processes shall be licensed by the department subject to compliance with the rules. The 

department may require payment of a fee as a condition of licensure. After the effective date of this 

amendment to this section, the department shall establish by rule a fee as a condition of licensure, 

including a maximum fee. As part of the rule making process, there must be public notice and comment 

and a review of the rule by the joint legislative budget committee. After September 30, 2013, the 

department shall not increase that fee by rule without specific statutory authority for the increase. The 

fees shall be deposited, pursuant to sections 35-146 and 35-147, in the solid waste fee fund established by 

section 49-881.

15. Perform the responsibilities of implementing and maintaining a data automation management system 

to support the reporting requirements of title III of the superfund amendments and reauthorization act of 

1986 (P.L. 99-499) and title 26, chapter 2, article 3.

16. Approve remediation levels pursuant to article 4 of this chapter.

17. Establish or revise fees by rule pursuant to the authority granted under title 44, chapter 9, article 8 and 

chapters 4 and 5 of this title for the department to adequately perform its duties. All fees shall be fairly 

assessed and impose the least burden and cost to the parties subject to the fees. In establishing or revising 

fees, the department shall base the fees on:

(a) The direct and indirect costs of the department's relevant duties, including employees salaries and 

benefits, professional and outside services, equipment, in-state travel and other necessary operational 

expenses directly related to issuing licenses as defined in title 41, chapter 6 and enforcing the 

requirements of the applicable regulatory program.

(b) The availability of other funds for the duties performed.

(c) The impact of the fees on the parties subject to the fees.

(d) The fees charged for similar duties performed by the department, other agencies and the private sector.

C. The department may:

1. Charge fees to cover the costs of all permits and inspections it performs to ensure compliance with 

rules adopted under section 49-203, except that state agencies are exempt from paying the fees. Monies 

collected pursuant to this subsection shall be deposited, pursuant to sections 35-146 and 35-147, in the 

water quality fee fund established by section 49-210.

2. Contract with private consultants for the purposes of assisting the department in reviewing applications 

for licenses, permits or other authorizations to determine whether an applicant meets the criteria for 

issuance of the license, permit or other authorization. If the department contracts with a consultant under 

this paragraph, an applicant may request that the department expedite the application review by 

requesting that the department use the services of the consultant and by agreeing to pay the department 

the costs of the consultant's services. Notwithstanding any other law, monies paid by applicants for 
expedited reviews pursuant to this paragraph are appropriated to the department for use in paying 

consultants for services.

D. The director may:

1. If the director has reasonable cause to believe that a violation of any environmental law or rule exists or 

is being committed, inspect any person or property in transit through this state and any vehicle in which 

the person or property is being transported and detain or disinfect the person, property or vehicle as 

reasonably necessary to protect the environment if a violation exists.

2. Authorize in writing any qualified officer or employee in the department to perform any act that the 

director is authorized or required to do by law.

49-106. Statewide application of rules

The rules adopted by the department apply and shall be observed throughout this state, or as provided by 

their terms, and the appropriate local officer, council or board shall enforce them. This section does not 

limit the authority of local governing bodies to adopt ordinances and rules within their respective 

jurisdictions if those ordinances and rules do not conflict with state law and are equal to or more 

restrictive than the rules of the department, but this section does not grant local governing bodies any 

authority not otherwise provided by separate state law.

49-404. State implementation plan

A. The director shall maintain a state implementation plan that provides for implementation, maintenance 

and enforcement of national ambient air quality standards and protection of visibility as required by the 

clean air act.

B. The director may adopt rules that describe procedures for adoption of revisions to the state 

implementation plan.

C. The state implementation plan and all revisions adopted before September 30, 1992 remain in effect 

according to their terms, except to the extent otherwise provided by the clean air act, inconsistent with 

any provision of the clean air act, or revised by the administrator. No control requirement in effect, or 

required to be adopted by an order, settlement agreement or plan in effect, before the enactment of the 

clean air act in any area which is a nonattainment or maintenance area for any air pollutant may be 

modified after enactment in any manner unless the modification insures equivalent or greater emission 

reductions of the air pollutant. The director shall evaluate and adopt revisions to the plan in conformity 

with federal regulations and guidelines promulgated by the administrator for those purposes until the rules 

required by subsection B are effective.
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ENCLOSURE 2

State Implementation Plan Completeness Checklist
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STATE IMPLEMENTATION PLAN COMPLETENESS CHECKLIST

Submittal of

Arizona State Implementation Plan Revision for the

Morenci Sulfur Dioxide Planning Area (1971 NAAQS) 

40 CFR Part 51, Appendix V, Criteria for Determining the Completeness of Plan Submissions, contains 

the “minimum criteria for determining whether a State Implementation Plan submitted for consideration 

by EPA is an official submission for purposes of review under §51.103,” Submission of plans, 

preliminary review of plans. Appendix V requires the following to be included in plan submissions for 

review by EPA:

1. "A formal letter of submittal from the Governor or his designee, requesting EPA acceptance of 

the plan or revision thereof (hereafter ‘‘the plan’’)." [Appendix V, 2.1(a)]

See cover letter.

2. "Evidence that the State has adopted the plan in the State code or body of regulations; or issued 

the permit, order, consent agreement (hereafter ‘‘document’’) in final form. That evidence shall 

include the date of adoption or final issuance as well as the effective date of the plan, if different 

from the adoption/issuance date." [Appendix V, 2.1(b)]

See cover letter

3. "Evidence that the State has the necessary legal authority under State law to adopt and 

implement the plan." [Appendix V, 2.1(c)]

Refer to Enclosure 1.

4. "A copy of the actual regulation, or document submitted for approval and incorporation by 

reference into the plan, including indication of the changes made (such as, 

redline/strikethrough) to the existing approved plan, where applicable ..." [Appendix V, 2.1(d)]

Refer to the Arizona State Implementation Plan Revision Maintenance Plan for the Morenci Sulfur 

Dioxide Planning Area (1971 NAAQS).

5. "Evidence that the State followed all of the procedural requirements of the State’s laws and 

constitution in conducting and completing the adoption/issuance of the plan." [Appendix V, 

2.1(e)]

Refer to cover letter, Enclosure 3, and Appendix E. 

6. "Evidence that public notice was given of the proposed change consistent with procedures 

approved by EPA, including the date of publication of such notice." [Appendix V, 2.1(f)]

Refer to Enclosure 3, Appendix E.

7. "Certification that public hearing(s) were held in accordance with the information provided in 

the public notice and the State’s laws and constitution, if applicable and consistent with the 

public hearing requirements in 40 CFR 51.102." [Appendix V, 2.1(g)]

Refer to Enclosure 3, Appendix E.

8. "Compilation of public comments and the State’s response thereto." [Appendix V, 2.1(h)]

Refer to Enclosure 3, Appendix E.
9. "Identification of all regulated pollutants affected by the plan." [Appendix V, 2.2(a)]

The regulated pollutant is Sulfur Dioxide (SO2).

10. "Identification of the locations of affected sources including the EPA attainment/nonattainment 

designation of the locations and the status of the attainment plan for the affected areas(s)." 

[Appendix V, 2.2 (b)]

See Enclosure 3, Chapters 1, Chapters 3 and 5.

11. "Quantification of the changes in plan allowable emissions from the affected sources; estimates 

of changes in current actual emissions from affected sources or, where appropriate, 

quantification of changes in actual emissions from affected sources through calculations of the 

differences between certain baseline levels and allowable emissions anticipated as a result of the 

revision." [Appendix V, 2.2(c)]

See Enclosure 3, Chapters 3, 4, and 5.

12. "The State’s demonstration that the national ambient air quality standards, prevention of 

significant deterioration increments, reasonable further progress demonstration, and visibility, 

as applicable, are protected if the plan is approved and implemented. For all requests to 

redesignate an area to attainment for a national primary ambient air quality standard, under 

section 107 of the Act, a revision must be submitted to provide for the maintenance of the 

national primary ambient air quality standards for at least 10 years as required by section 175A 

of the Act." [Appendix V, 2.2(d)]

See Enclosure 3, Chapters 4, 5, and 6.

13. "Modeling information required to support the proposed revision, including input data, output 

data, models used, justification of model selections, ambient monitoring data used, 

meteorological data used, justification for use of offsite data (where used), modes of models 

used, assumptions, and other information relevant to the determination of adequacy of the 

modeling analysis." [Appendix V, 2.2(e)]

See Enclosure 3, Chapter 5.

14. "Evidence, where necessary, that emission limitations are based on continuous emission 

reduction technology." [Appendix V, 2.2(f)]

Not applicable. 

15. "Evidence that the plan contains emission limitations, work practice standards and 

recordkeeping/reporting requirements, where necessary, to ensure emission levels." [Appendix 

V, 2.2(g)]

Not applicable. 

16. "Compliance/enforcement strategies, including how compliance will be determined in 

practice." [Appendix V, 2.2(h)]

See Enclosure 3, Chapter 6.

17. "Special economic and technological justifications required by any applicable EPA policies, or 

an explanation of why such justifications are not necessary." [Appendix V, 2.2(i)]

No known deviation from EPA policy. 
ENCLOSURE 3

Arizona State Implementation Plan Revision

Maintenance Plan for the Morenci Sulfur Dioxide Planning Area (1971 NAAQS)

December 2014
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FINAL

Arizona State Implementation Plan Revision

Maintenance Plan for the

Morenci Sulfur Dioxide Planning Area

(1971 NAAQS)

Air Quality Division

December 18, 2014
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i 

Table of Contents 

Table of Contents ............................................................................................................................. i

List of Executive Summary Figures .............................................................................................. iii

List of Figures ................................................................................................................................ iii

List of Tables ................................................................................................................................. iii

List of Appendices ......................................................................................................................... iii

EXECUTIVE SUMMARY .............................................................................................................1

1.0 INTRODUCTION ...............................................................................................................3

1.1 Statement of Introduction and Purpose ...................................................................... 3

1.2 National Ambient Air Quality Standards ................................................................... 3

1.3 Sulfur Dioxide Air Quality Standards........................................................................ 3

1.4 Regulatory Background ............................................................................................. 4

1.5 Morenci Sulfur Dioxide Planning Area Description ................................................. 7

1.5.1 Morenci Sulfur Dioxide Planning Area Boundary ..................................... 7

1.5.2 Geography and Climate .............................................................................. 9

1.5.3 Population ................................................................................................... 9

1.5.4 Economy ................................................................................................... 10

1.6 General SIP Approach – Regulatory Requirements and Guidance ......................... 10

1.6.1 Clean Air Act Requirements for Maintenance Plans ................................ 11

1.6.2 Clean Air Act Conformity Provisions....................................................... 11

1.6.3 EPA Guidance ........................................................................................... 12

2.0 AIR QUALITY MONITORING .......................................................................................14

2.1 Monitoring Site, Equipment, and Quality Assurance Procedure ............................. 14

2.2 SO2 Data Summary ............................................................................................... 15

3.0 EMISSIONS INVENTORIES AND PROJECTIONS TO 2030 .......................................17

3.1 Emissions Inventories (Historical) ........................................................................... 18

3.1.1 Point Sources ............................................................................................ 18

3.1.2 Area and Mobile Sources .......................................................................... 18

3.2 2011 Emissions Inventory (Current) ........................................................................ 19

3.2.1 Point Sources ............................................................................................ 19

3.2.2 Totals for Mobile, Area and Point Sources ............................................... 22

3.3 Emissions Projections .............................................................................................. 22

3.3.1 Point Source Projections .............................................................................. 22

3.3.2 Point Source Projections .............................................................................. 22

4.0 CONTROL MEASURES ..................................................................................................25

4.1 Point Sources ........................................................................................................... 25

4.2 Area and Mobile Sources ......................................................................................... 25

5.0 MODELING DEMONSTRATION ...................................................................................27

5.1 Historical Modeling Analysis .................................................................................. 27

5.2 Current Modeling Demonstration ............................................................................ 27

6.0 MAINTENANCE PLAN SUMMARY .............................................................................30

6.1 Emissions Inventories .............................................................................................. 30

6.2 Maintenance Demonstration .................................................................................... 30

6.3 Ambient Monitoring ................................................................................................ 31

6.5 Contingency Plan ..................................................................................................... 32
ii

6.6 Conclusion ............................................................................................................... 33
iii

List of Executive Summary Figures

ES- 1 Total SO2 Sources within Morenci Maintenance Area .......................................................................1

List of Figures

Figure 1.1: Morenci Sulfur Dioxide Planning Area......................................................................................8

Figure 3.1: Morenci Sulfur Dioxide Planning Area and 50 km Buffer Area Point Sources.......................21

Figure 6.1: SO2 Emissions for Years 1984-2030........................................................................................31

List of Tables

Table 1.1 1971 Sulfur Dioxide National Ambient Air Quality Standards....................................................4

Table 1.2 Morenci Sulfur Dioxide Area Description....................................................................................7

Table 1.3 Greenlee County Population Estimates ........................................................................................9

Table 1.4 Labor Force Data for Morenci and Clifton .................................................................................10

Table 2.1: State of Arizona Morenci SO2 Ambient Air Quality Monitors .................................................15

Table 2.2: Phelps Dodge Morenci SO2 Ambient Air Quality Stationary and Mobile Monitors................15

Table 3.1: Total Historical Potential to Emit and Actual Emissions in tons for years 1984 and 1999.......18

Table 3.2: Historical Greenlee County and Morenci Area and Mobile Source Emissions in tons.............18

Table 3.3: SO2 Point Sources within Morenci Planning Area ....................................................................19

Table 3.4: SO2 Point Sources within 50-km Buffer....................................................................................20

Table 3.5: Total SO2 Emissions for the Morenci Planning Area-2011.......................................................22

Table 3.6: Point Source Projections in Planning Area to 2030...................................................................23

Table 3.7: Point Source Projections within the 50km Buffer Area.............................................................23

Table 3.8: Area and Mobile Sources SO2 Emissions Projections for the Morenci Planning Area .............24

Table 5.1: Emissions of SO2 for FMMM and FMSM in Renewal Permits................................................28

Table 5.2: Cumulative Impacts of FMMM and FMSM on the Morenci Maintenance Area ......................29

Table 5.3: Cumulative Impacts of FMMM and FMSM on the Morenci Maintenance Area Boundary .....29

List of Appendices

Appendix A Procedures for Processing Requests to Redesignate Areas to Attainment, Memorandum, 

John Calcagni, Director, Air Quality Management Division, U.S. Environmental Protection 

Appendix B Redesignation of Sulfur Dioxide Nonattainment Areas in the Absence of Monitored 

Data, Memorandum, John Seitz, Director, Office of Air Quality Planning and Standards,

U.S. Environmental Protection Agency, October 18, 2000

Appendix C Morenci Maintenance Plan Emissions Inventory

Appendix D Morenci Modeling Analysis 

Appendix E State Implementation Plan Revision Public Comment and Hearing Documentation
iv

E.1 Notice of Public Hearing

E.2 Public Hearing Agenda

E.3 Public Hearing Sign-In Sheet

E.4 Public Hearing Officer Certification and Transcript

E.5 Responsiveness Summary
1

EXECUTIVE SUMMARY

The Morenci Sulfur Dioxide (SO2) Maintenance Plan demonstrates that the Morenci planning area will continue to 

meet the 1971 health-based 24-hour and annual SO2 National Ambient Air Quality Standards (NAAQS) for a 

second maintenance period, through 2030. 

An overview of the NAAQS and Clean Air Act (CAA) Requirements are discussed in further detail in Chapter 1. 

This chapter also gives a summary of the regulatory background including boundary designations and describes the

planning area’s geography, climate, population, and economy. 

Chapter 2 presents the history of the monitoring network and the monitoring requirements of the planning area. Due 

to the closure of facility on December 31, 1984, which was the primary source of SO2 emissions, no ambient 

monitors are currently in operation within the area. If a new major source is constructed in the planning area, the 

Arizona Department of Environmental Quality (ADEQ) will develop and implement an appropriate monitoring 

network according to federal and state regulations.

Emissions inventories in Chapter 3 reveal that while in operation, the Phelps Dodge Mining Company’s primary 

copper smelter was the largest point source in the Morenci Nonattainment Area.ES[1] Figure ES-1 shows that no 

other point, area, or mobile source has generated or currently generates as high a level of SO2 emissions in the area 

as the smelter did when in operation. The smelter permanently deactivated in December 1984. Dismantling of the 

facility began in 1995 and reclamation was completed by December 1996. In 1997, ADEQ verified that the Phelps 

Dodge Morenci smelter was closed and dismantled. The closure of this facility resulted in permanent significant 

emissions reductions.

Figure ES-1 illustrates point source emissions reductions due to the closure of the smelter and shows that future 

emissions remain low enough to not cause a violation of the NAAQS. The 1984 and 2011 levels are based on actual 

emission estimates, while projected emission estimates are based on the potential to emit (PTE) of extant sources. 

The 2030 inventory represents emissions projected through the second ten-year maintenance period.

 

ES- 1 Total SO2 Sources within Morenci Maintenance Area

 

ES[1]

Freeport-McMoRan bought the Phelps Dodge Corporation in 

2007;http://seagoedd.org/?s=population+morenci.

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000

100,000

1984 2011 2015 2025 2050

82,432.00

48.54 87.6 87.6 87.6

Tons 

Years

SO2 Emissions
2

Chapter 4 describes the implementation of primary control measures used to achieve attainment and maintenance of 

the SO2 NAAQS. For previous SIP revisions, EPA has considered the closure of the smelter as sufficient to meet 

reasonably available control measure (RACM) requirements in the Morenci planning area. Additional measures to 

ensure continued attainment of the SO2 NAAQS are implemented through state and county permitting requirements. 

There are also several national programs that integrate engine and fuel controls for highway vehicles and non-road 

equipment to reduce SO2 emissions for area and mobile sources.

The modeling analysis contained in Chapter 5 demonstrates continued attainment of the NAAQS. The analysis

includes two of the largest sources within the planning area, Freeport McMoRan Mine and Safford Mine. The 

model estimates that the mines, which emit a combined total of about 169 tons per year of SO2, do not contribute to 

violations of the 1971 SO2 NAAQS.

Chapter 6 summarizes the measures that ensure continued maintenance of the NAAQS through the year 2030. This 

discussion shows the permanence and enforceability of the emission reductions responsible for the air quality 

improvement and attainment of the NAAQS. Maintenance of the SO2 NAAQS in the Morenci area will be tracked 

through updates to the emissions inventory and permit applications received for SO2 emitting sources. The Chapter 

also includes a commitment to resume ambient monitoring before any new major SO2 source begins operation in the 

area.

The permanent and enforceable control measures and projections of future emissions presented in this document 

demonstrate that the Morenci area will continue to maintain the SO2 air quality standards. With this submittal,

ADEQ requests that EPA approve this maintenance plan for the 1971 SO2 24-hour and annual NAAQS through 

2030 in accordance with CAA §175A.
3

1.0 INTRODUCTION 

Chapter 1 describes the purpose of this State Implementation Plan (SIP) revision for the Morenci Sulfur 

Dioxide (SO2) Planning Area, summarizes the regulatory background of the area, and provides a general 

overview of the area and county.

1.1 Statement of Introduction and Purpose

This SIP revision demonstrates that the Morenci Planning Area will continue to meet the 1971 healthbased 24-hour average and annual average SO2 National Ambient Air Quality Standards (NAAQS) for a 

second maintenance period, through 2030. 

The Morenci Sulfur Dioxide Nonattainment Area State Implementation and Maintenance Plan and 

redesignation request was submitted to the U.S. Environmental Protection Agency (EPA) in June 2002. 

The SIP revision summarized the progress of the area towards attaining the SO2 standards, demonstrated 

that all Clean Air Act (CAA) requirements had been satisfied, and included a maintenance plan to assure 

the area would continue to attain the standard after redesignation, through 2015. EPA approved the plan 

and redesignated the area to attainment effective June 25, 2004 (69 FR 22447; April 26, 2004). Section

175A(a) of the CAA requires states to demonstrate maintenance of the NAAQS for at least ten years after 

redesignation to attainment. The effective first maintenance period for the Morenci area is 2004 through 

2015.

A subsequent SIP revision, under CAA Section 175A(b), is due eight years after an area is redesignated to 

attainment in order to provide for maintenance of the NAAQS for an additional 10 years after the 

expiration of the first 10-year maintenance period. The information contained in this document shows 

that the air quality standards will continue to be maintained from the expiration of the first maintenance 

period through 2030.

1.2 National Ambient Air Quality Standards 

Title I of the CAA requires EPA to set NAAQS for those pollutants considered harmful to both public 

health and the environment. EPA set standards for six air pollutants: ground-level ozone, particulate 

matter, carbon monoxide, nitrogen dioxide, sulfur dioxide and lead. There are two types of NAAQS: 

primary and secondary. Primary standards are set to protect human health and established secondary 

standards protect public welfare, such as decreased visibility and damage to animals, crops, vegetation

and buildings. 

The standard for each pollutant is set at a maximum concentration in either parts per million (ppm) by 

volume, parts per billion (ppb) by volume, or micrograms per cubic meter of air (μg/m3). Each standard 

also has a distinct averaging time that provides the necessary level of protection. These standards are 

reviewed every five years and are retained or revised based on review of scientific literature and analyses.

1.3 Sulfur Dioxide Air Quality Standards

The federal air quality standards for SO2 were established in 1971 and identified ambient concentrations 

that affect human health and welfare. The original primary and secondary NAAQS for SO2 were codified 

in Volume 42 of the Code of Federal Regulations (CFR), Part 410 (42 CFR Part 410) on April 30, 1971 
4

(36 FR 81875), and recodified in 40 CFR 50.4 and 50.5 on November 25, 1971 (36 FR 22384). On May 

22, 1996, EPA promulgated several technical changes; however, no changes were made to the level of the

standards at that time (61 FR 25566).1 Table 1.1 shows the 1971 primary and secondary SO2 NAAQS, as 

modified in 1996. Arizona adopted these standards at Arizona Administrative Code (AAC) R18-2-202, 

effective May 05, 2011.

Table 1.1 1971 Sulfur Dioxide National Ambient Air Quality Standards

Final 

Rule/Decision

Primary/

Secondary

Averaging

Time Level Form

1971

Primary 24-Hour 0.14 ppm 365

μg/m3

Not to be exceeded more 

than once per year

Annual 0.03 ppm 80 μg/m3 Annual arithmetic average

Secondary2 3-Hour 0.5 ppm 1300 

μg/m3

Not to be exceeded more 

than once per year

Annual 0.02 ppm 52 μg/m3 Annual arithmetic average

1973 Secondary Secondary 3-hour SO2 standard retained, without revision; secondary 

annual SO2 standard revoked.

1996 Primary Existing primary SO2 standards retained, without revision.

Source: http://www.epa.gov/ttn/naaqs/standards/so2/s_so2_history.html.

On June 22, 2010, EPA replaced the existing annual and 24-hour primary SO2 standards with a new 1-

hour SO2 standard set a level of 75 ppb to better protect public health by reducing public exposure to 

elevated short-term concentrations of SO2 (75 FR 35520; effective August 23, 2010). Planning 

obligations for the 1971 standards, including this renewal of the Morenci maintenance plan, continue until 

they are subsumed by planning and control requirements associated with new NAAQS. 

On December 8, 2009, EPA proposed to retain the current SO2 secondary standard to provide requisite 

protection for the direct effects on vegetation and ecosystems (74 FR 64810).3 At the same time, EPA 

proposed to add a secondary standard identical to the new primary SO2 1-hour standard set at 75 ppb. In 

its notice of final rulemaking EPA retained the current secondary standard but did not add a secondary 

standard at the level of the new primary standard (77 FR 20218; April 3, 2012). This plan does not 

address the 2010 NAAQS for SO2.

1.4 Regulatory Background

The relationship between major SO2 point sources and ambient air quality is relatively well defined. The 

Phelps Dodge Morenci, Inc. copper smelting facility (PDMI) was the largest SO2 point source in the 

Morenci area during its operation. Data show that no other point, area or mobile sources contributed in 

the past or currently contribute at the same levels of SO2 emissions as those attributed to the smelter. 

 

1 Technical changes included stating the standards in parts per million (ppm) to make the SO2 NAAQS consistent 

with those for other pollutants. The former standards, stated in micrograms per cubic meter (μg/m3) are included in 

this document for consistency with historic data collection, reporting, and analyses. 

2 The 1971 SO2 NAAQS originally included a secondary standard at 0.02 ppm in an annual arithmetic mean. In 

1973 EPA proposed and finalized revocation of the annual mean secondary standard (38 FR 11355; May 7, 1973 

and 38 FR 25678; September 14, 1973). 

3

http://www.epa.gov/ttn/naaqs/standards/so2/fr/20091208p64810.pdf
5

PDMI was located next to the Morenci copper mine in the Gila River air shed at an elevation of about 

4,500 feet above sea level.4

Areas that do not meet the NAAQS may be designated nonattainment for the respective standard. The 

Morenci SO2 Nonattainment Area, designated for the 1971 annual and 24-hour primary standards, 

initially encompassed all of Greenlee County (43 FR 8968; March 3, 1978). At the request of the State of 

Arizona, the boundaries were reduced to eight whole or partial townships roughly centered on the primary 

copper smelter in Morenci (44 FR 21261; April 10, 1979). In addition, one adjacent township was

designated as unclassifiable. 

As required by the CAA, Arizona submitted a SIP in 1971 for all major sources in the State. The portion 

of the plan pertaining to attainment and maintenance of the NAAQS for SO2 did not sufficiently define 

emissions limitations or require permanent control of emissions for existing copper smelters and was 

disapproved on July 27, 1972 (37 FR 15081). On the same date, EPA proposed revised regulations for 

control of sulfur oxides emitted by all existing smelters in Arizona (37 FR 15096). These regulations 

were not finalized due to issues regarding the adequacy of the ambient air quality data used to develop 

the limits. EPA subsequently established an SO2 monitoring network around each smelter in the State to 

gather air quality data from June 1973, through October 1974, and provide a basis for emissions 

limitations. 

EPA and State efforts to develop comprehensive emissions limits continued through the 1970s. In 1977, 

the State developed rules for the use of Supplementary Control Systems (SCS), which would utilize

ambient monitoring data and allow Arizona smelters to intermittently curtail operations and emissions to 

prevent violations of the SO2 NAAQS. EPA disapproved this approach and required installation and 

continuous operation of permanent SO2 emissions controls adequate to ensure attainment of the NAAQS. 

On January 4, 1978, EPA published final emissions limits for Arizona smelters based on air quality data

from 1973 to 1974 and the use of a proportional rollback model (43 FR 755). The regulations specified 

maximum emissions rates and compliance test methods for seven Arizona smelters. 

The 1977 Clean Air Act Amendments (CAAA) modified smelter control requirements and allowed the 

temporary use of SCS while final SO2 emission limits were developed and also allowed more time for 

certain smelters to install emissions control technology. In response to this action, Arizona began 

development of new regulations and on September 20, 1979, submitted Ultimate Sulfur Dioxide Emission 

Limits for Arizona Copper Smelters as a proposed revision to the Arizona SIP.5

The new regulations were developed using a “Multi-Point Rollback (MPR)” technique. The use of MPR 

to establish emissions limits addressed the problem of variable SO2 emissions from smelting operations 

and variable meteorological conditions, which define ambient concentrations, by correlating the 

frequency of short-term emissions at various levels with the probability of violating the ambient air 

quality standards. This technique “rolled back” a yearly emissions profile to a level protective of the 

standards. The new regulations established stack emission limits for smelters and set requirements for 

analyzing the impact of fugitive SO2 emissions on ambient air quality. The rule required all existing 

primary copper smelters in Arizona to implement control technology sufficient to comply with the new 

 

4 The smelter’s geographic coordinates were latitude of 33 3'49.3" N and a longitude coordinate of 109, 20'30.5W.

5

Site specific emissions limits were promulgated at Arizona Administrative Rules and Regulations (AARR) R9-3-

515, later revised and recodified as Arizona Administrative Code (AAC) R18-2-715, Standards of Performance for 

Existing Primary Copper Smelters; Site-specific Requirements, R18-2-715.01, Standards of Performance for 

Existing Primary Copper Smelters; Compliance and Monitoring, and R18-2-715.02, Standards of Performance for 

Existing Primary Copper Smelters; Fugitive Emissions. 
6

stack limits as well as any fugitive emissions controls necessary to assure attainment and maintenance of 

the NAAQS. 

On November 30, 1981, EPA proposed conditional approval of Arizona’s Multipoint Rollback (MPR)

SIP revision (46 FR 58098). On June 3, 1982, Arizona submitted revisions to correct the conditional 

approval. EPA formally approved Arizona’s MPR rules as a component of the SIP on January 14, 1983 

(48 FR 1717). The rules included performance standards for each existing primary copper smelter (see 

Arizona Administrative Code (AAC) R18-2-715, R18-715.02). Rule R18-2-715.01 (D) identified 

January 14, 1986, as the general compliance date for the provisions of the Section. Arizona’s SIP 

revisions were designed to meet the requirements of CAA §§ 110 (state implementation plans) and 123 

(smelter stack heights) as amended in 1977 and replaced EPA’s January 4, 1978, SO2 control regulations 

applicable to Arizona copper smelters. To complete the Arizona SO2 SIP, EPA required that Arizona 

submit necessary fugitive emissions control strategies and regulations for existing smelters by August 1, 

1984. 

PDMI was subject to a Delayed Compliance Order from 1981 and an earlier compliance date of January 

1, 1985.6 On March 4, 1982, Phelps Dodge responded to EPA, requesting an 18-month delay in its

Compliance Order dates for its Morenci copper smelter, due to financial difficulties. EPA denied the 

request. On April 17, 1982, PDMI temporarily ceased copper smelting activities, recommencing 

operations October 12, 1982, initiating use of oxygen-fuel, oxygen sprinkle smelting systems in its 

number 3 furnaces in November 1982, as mandated in the PDMI Delayed Compliance/Innovative 

Technology Orders (DCO/ITOs). 

PDMI permanently deactivated December 31, 1984. Additionally, all ambient air quality monitoring was 

discontinued at the time of the shutdown. Dismantlement of the Morenci facility began in 1995 and 

reclamation was complete by December 1996. On October 29, 1997, the Arizona Department of 

Environmental Quality (ADEQ) verified that the Phelps Dodge Morenci smelter was closed and 

dismantled (see the 2002 SIP submittal, section 1.2 for details). 

In June 2002, ADEQ submitted to EPA the Morenci Sulfur Dioxide Nonattainment Area State 

Implementation and Maintenance Plan and a request to redesignate the area to attainment. CAA Section 

175A(a) requires that maintenance of the NAAQS be demonstrated for at least ten years after 

redesignation to attainment. The SIP contained demonstrations that the Morenci area attained and would 

continue to maintain the 1971 SO2 NAAQS through 2015. The SIP also included a commitment to 

submit a subsequent SIP revision to ensure maintenance of the NAAQS in the redesignated area for a 

second maintenance period as required by CAA Section 175A(b). EPA approved the 2002 plan under 

CAA Sections 110 and 175A and redesignated the area to attainment for the primary SO2 NAAQS on 

April 26, 2004(69 FR 22447; effective June 25, 2004).

7

 

This SIP revision demonstrates continued attainment of the 1971 primary SO2 NAAQS for a second

maintenance period through 2030.

 

6 The emission regulations violated were defined in Arizona’s 1979 SIP and in 40 CFR §52.125(d) and Regulation 

7-1-3.6 of the Rules and Regulations for Air Pollution Control of the Arizona State Department of Health (ADHS). 

After issuance of notices to Phelps Dodge for violations of emission regulations at the Morenci smelter, EPA and 

PDMI negotiated and agreed to Delayed Compliance/Innovative Technology Orders (DCO/ITOs)under CAA § 

113(d)(4)(46 FR 49604 (1984)). EPA issued the final Orders on January 12, 1982 (47 FR 1293). EPA amended the 

DCO/ITO issued PDMI on July 23, 1984 (49 FR 24090). Although the 1984 amendments to the PDMI consent 

decree changed some interim compliance dates, the SO2 compliance deadline remained January 1, 1985.

7

For additional information on the approval of the Morenci plan see: 

http://www.epa.gov/region09/air/az/morenci/index.html.
7

1.5 Morenci Sulfur Dioxide Planning Area Description

Sections 1.5.1 through 1.5.4 describe the boundary, geography and climate, demographics, and economy 

of the Morenci planning area. 

1.5.1 Morenci Sulfur Dioxide Planning Area Boundary

The current boundaries of the planning area are codified at 40 CFR § 81.303 (1979) and are defined by 

the townships listed in Table 1.2. Figure 1.1, portrays the townships and ranges within the planning area. 

Table 1.2 Morenci Sulfur Dioxide Area Description

Designated Area Better Than National 

Standards Cannot Be Classified

T3S, R28E* X

T3S, R29E X

T3S, R30E X

T4S, R28E* X

T4S, R29E X

T4S, R30E X

T5S, R28E* X

T5S, R29E* X

T5S, R30E X

*Only that portion in Greenlee County.8

 

8

40 CFR§ 81.303 (1979) Ch. 1 (7-1-10 Edition); (http://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol17/pdf/CFR2010-title40-vol17-sec81-303.pdf).
8

Figure 1.1: Morenci Sulfur Dioxide Planning Area
9

1.5.2 Geography and Climate 

The Morenci SO2 Planning Area is located in western Greenlee County approximately nine miles west of 

the Arizona/New Mexico border. Greenlee County covers a land area of 1,847 square miles and contains

diverse terrain and climate, from upland desert at its southern tip to high alpine country rising to more 

than 9,000 feet above sea level at points along the Mogollon Rim. 

The diverse nature of the topography in the County creates wide temperature variations. In the Morenci 

area, the hottest month of the year is July, when the average daily maximum temperature is 101.4°

Fahrenheit (F) and the average daily minimum temperature is 71.3° F. The coolest month of the year is 

January, when the average daily maximum temperature is 61.2° F and the average daily minimum 

temperature is 31.1° F. The heaviest rainfall of the year occurs in July and August; average total

precipitation for those months is 2.17 inches and 2.27 inches, respectively. The driest months of the year 

are May and June, when average total precipitation is 0.22 inches and 0.33 inches. The average annual 

precipitation in the Morenci area is 12.06 inches.9

1.5.3 Population

Population statistics provide information about the number of people affected by changes in air quality in 

the Morenci planning area and can be used as a surrogate for estimating current and future emissions from 

certain source categories (see Chapter 4). 

In the 1970s, when rural counties outpaced the growth of urban counties in the U.S., rural Greenlee 

County grew by slightly more than 10%. However, during the 1980s, Greenlee County’s population 

declined almost 30% and the population in the unincorporated Morenci area, defined as a ‘Census 

Designated Place’ (CDP) by the Census Bureau, decreased by 34%.

10

According to the Arizona Department of Administration (ADOA), the population of Greenlee County in 

2011 was estimated at 8,380 residents, which corresponds to the population provided by the U.S. Census 

Bureau. By 2030, the population in the county is expected to increase by 188 people. The population in 

the Morenci area is projected to increase by 30 residents by 2030, resulting in a total of 1,512 people. 

The population of Clifton and Morenci CDP defines the maintenance area population and is 

approximately 57% of the Greenlee County population. Table 1.3 illustrates the population trend between 

2011 and 2030, which indicates a slight increase in Greenlee County, Clifton, and the Morenci CDP. 

Table 1.3 Greenlee County Population Estimates

Location 2011 2015 2020 2025 2030

Clifton 3,273 3,299 3,323 3,340 3,350

Morenci CDP 1,482 1,489 1,500 1,508 1,512

Greenlee County 8,380 8,437 8,499 8,543 8,568

http://www.workforce.az.gov/population-projections.aspx

 

9

Source of data is the Arizona Department of Commerce Community Profile for Morenci/Clifton, February 2001.

10 AZ Dept of Economic Security and U.S. Census Bureau. See page 1.5 of 2002 SIP.
10

1.5.4 Economy

In 2012, Freeport McMoRan Incorporated (FMMM) generated $365.4 million through the Safford and 

Morenci mining operations, which had an economic impact on Greenlee, Graham County, and the State. 

By the end of the year, FMMM employed over 2,600 people at the Morenci mine. Compensation from 

FMMM in Greenlee and Graham counties is estimated at $253.8 million, business taxes at $15.1 million, 

and vendor purchases at $25.5 million, with a direct impact totaling $294.4 million. The indirect impact 

totaled $71 million because of spending from employees, new tax revenues, and vendor purchases. The 

total from direct and indirect impacts from FMMM is $365.4 million in Greenlee and Graham counties. 

The revenue generated from FMMM is estimated at $1.1 billion dollars.11

Other employment sectors in Greenlee County include tourism, agriculture, government, education, retail 

trade, health and social assistance.

12 The top occupations in Morenci are in the areas of natural resources, 

construction, and maintenance occupations, which accounts for 28.3% of total income for the city. 

According to USA City Facts, the unemployment rate is high in Morenci at 16.7%; the national average is 

7.9%.

13

 Significant economic development is unlikely because 77.1% of land is U.S. Forest Service and 

U.S. Bureau of Land Management and only 8.1% of land is privately owned. Table 1.4 gives an overview 

of labor force, unemployment, and unemployment rate for the Morenci and Clifton area. 

Table 1.4 Labor Force Data for Morenci and Clifton

Employment 

Statistic (Annual 

Average)

1990 1995 2000 2005 2010 2011

Morenci Labor Force 792 1,188 996 879 1009 n/a

Morenci Unemployed 59 74 22 22 62 n/a

Morenci 

Unemployment Rate 7.4% 6.2% 2.2% 2.5% 6.1% n/a

Clifton Labor Force n/a n/a 1155 1025 1257 1549

Clifton Unemployed n/a n/a 72 73 205 108

Clifton

Unemployment Rate n/a n/a 6.2% 7.1% 16.3% 7.0%

Source: Average annual labor force data, Arizona Department of Administration, Local Area Unemployment 

Statistics, updated December 15, 2011.14

1.6 General SIP Approach – Regulatory Requirements and Guidance

In November 1990, the U.S. Congress enacted a series of amendments to the CAA. One of the primary 

effects of the revision was to expand and clarify the planning provisions for those areas not meeting the 

NAAQS. The CAA, as amended, authorizes comprehensive federal and state programs to provide for 

attainment and maintenance of the NAAQS. Sections 1.6.1 and 1.6.2 outline CAA requirements for SO2

maintenance areas. In addition, EPA has published guidance documents to clarify environmental 

 

11 “Morenci”; (http://www.fcx.com/operations/usa_arizona_morenci.htm).

“Economic Benefits of the Morenci and Safford Mines upon Greenlee/Graham Counties and Arizona-2012 ”; 

(http://www.fcx.com/sd/pdf/fast_facts/2013/MorenciSafford_EI_2013.pdf).

12 “Greenlee County industries and sales”;( http://seagoedd.org/?s=population+morenci).

13 http://www.usacityfacts.com/az/greenlee/morenci/economy/

14 Population Projections ;(http://www.workforce.az.gov/population-projections.aspx).

“Local Area Unemployment Statistics (LAU)”; (http://azstats.gov/local-area-unemployment-statistics.aspx).
11

regulations relating to maintenance of the NAAQS and to assist in developing approaches for 

implementing those regulations. Section 1.6.3 summarizes applicable EPA guidance.

1.6.1 Clean Air Act Requirements for Maintenance Plans

Title I, Part A, and Title I, Part D, Subparts 1 and 5 of the CAA contain the nonattainment and 

maintenance requirements for SO2 planning areas. Part D, Subpart 1, Section 175A provides the general 

framework for maintenance plans as summarized below.

CAA § 175A(a). Plan Revision

Under Section 175A(a) maintenance plans must provide for maintenance of the primary 

ambient air quality standards for at least 10 years after redesignation, including any 

additional control measures as may be necessary to ensure such maintenance. 

CAA § 175A(b). Subsequent Plan Revisions

Eight years after redesignation of any area as an attainment area, CAA Section 175(A)(b)

requires the state to submit an additional revision of the applicable state implementation 

plan for maintaining the national primary ambient air quality standard for 10 years after 

the expiration of the first 10-year maintenance period.

CAA § 175A(c). Nonattainment Requirements Applicable Pending plan Approval

Under Section 175A(c), pending EPA approval of a SIP revision and request for 

redesignation of a nonattainment area to attainment, applicable nonattainment area 

requirements shall remain in full force and effect concerning that area. 

CAA § 175A(d). Contingency Provisions

Section 175A(d) requires maintenance plans to contain any necessary contingency 

provisions to assure prompt correction of a violation of the NAAQS that occurs after 

redesignation to attainment. The contingency measures must include a requirement that 

the state will implement all control measures contained in the SIP for the area prior to 

redesignation.

1.6.2 Clean Air Act Conformity Provisions

CAA Section 176(c)(1)(A) requires SIPs to contain information regarding the State’s compliance with 

conformity requirements. 

Transportation Conformity

As stated in 40 CFR § 93.153(b), "Conformity determinations for federal actions related to transportation 

plans, programs and projects developed, funded, or approved under title 23 U.S.C. or the Federal Transit 

Act (40 U.S.C. § 1601 et seq.) must meet the procedures and criteria of 40 CFR Part 51, subpart T, in lieu 

of the procedures set forth in this subpart.” Title 40 CFR § 93.102(b) waives transportation conformity 

for SO2 nonattainment and maintenance areas.

General Conformity

General conformity for the Morenci, Greenlee County area must still be addressed to assure SO2

emissions from any federal actions or plans do not exceed the rates outlined in 40 CFR § 93.153(b) (see 

58 FR 63253; November 30, 1993). Criteria for making determinations and provisions for general 

conformity are located in R18-2-1438 of the Arizona Administrative Code. There are no known federal 

plans or actions currently affecting air quality in the Morenci area nor are any foreseen through the year 
12

2025. ADEQ commits to review and comment, as appropriate, on any federal agency general conformity 

determination it receives pursuant to 40 CFR § 93.155 for activities planned for this air quality planning 

area.

1.6.3 EPA Guidance

Applicable guidance for demonstrating maintenance of the NAAQS includes the following EPA 

memoranda:

The September 4, 1992, Memorandum, Procedures for Processing Requests to Redesignate Areas to 

Attainment, John Calcagni, Director, Air Quality Management Division, U.S. Environmental Protection 

Agency (see Appendix A), recommends several core provisions for states to consider when developing 

maintenance plans. These provisions include:

1) An attainment emissions inventory to identify the level of emissions 

sufficient to attain the NAAQS,

2) A maintenance demonstration that either shows that future emissions 

will not exceed the level of the attainment inventory or includes a 

modeling analysis to show that the future mix of sources will not cause a 

violation of the NAAQS,

3) Continued operation of an appropriate air quality-monitoring network to 

verify the attainment status of an area,

4) Verification of continued attainment through tracking changes in the 

emissions inventory, or other methods, as well as assurance that the state 

has the legal authority necessary to implement and enforce all measures 

used to attain and maintain the NAAQS, and

5) A Contingency Plan designed to correct any violation of the NAAQS 

after redesignation of the area to attainment.

EPA's historic redesignation policy has called for eight quarters of clean ambient air quality data as a 

prerequisite for redesignation of an area to attainment. The October 18, 2000, Memorandum, 

Redesignation of Sulfur Dioxide Nonattainment Areas in the Absence of Monitored Data, from John 

Seitz, Director of the Office of Air Quality Planning and Standards (see Appendix B), was developed to 

provide guidance on redesignating SO2 areas to attainment where an area's historic violations were caused 

by major point sources of SO2 emissions that are no longer in operation and where SO2 monitors were 

removed immediately following the shutdown of the emissions sources, and therefore lack sufficient air 

quality data demonstrating attainment of the standard. 

The guidance provides an approach for demonstrating attainment and maintenance of the air quality 

standards and exempts these areas from requirements for continued ambient monitoring. Four separate 

elements for demonstrating maintenance of the SO2 NAAQS are outlined below:

1) Emissions inventories representing actual emissions when violations 

occurred, current emissions, and emissions projected to the 10th year 

after redesignation;
13

2) Dispersion modeling analysis of all point sources in, and within 50 

kilometers (km) of, the nonattainment area boundary showing that no 

NAAQS violations occur or can be projected for the next 10 years 

anywhere within the nonattainment area, and that the shutdown source or 

sources were the dominant cause of the high concentrations in the past;

3) Evidence that if the shutdown source or sources resume operation they 

will be considered new sources and be required to obtain a permit under 

the Prevention of Significant Deterioration program, and

4) A commitment to resume monitoring before any major SOx source 

commences operation.
14

2.0 AIR QUALITY MONITORING

No ambient monitors are currently in operation within the Morenci SO2 planning area. The information 

in this section provides historical background to compare the status of air quality to a time when 

exceedances of the NAAQS occurred. 

Ambient monitoring networks for air quality are established to sample pollution in a variety of 

representative settings, to assess health and welfare impacts and to assist in determining air pollution 

sources. These networks contain individual monitoring sites that are operated by a number of government 

agencies and regulated companies. The data gathered by the monitors within the are statistically analyzed 

and compared to the NAAQS. 

EPA’s protocols for SO2 monitoring are located in the following sections of the Code of Federal 

Regulations (CFR):

1. 40 CFR Part 50, Appendix A, Reference Method for the Determination of Sulfur Dioxide 

in the Atmosphere;

2. 40 CFR Part 53, Subpart B, Procedures for Testing Performance Characteristics of 

Automated Methods for SO2, CO, O3, and NO2; and

3. 40 CFR Part 58, Subpart A, B, and C, Ambient Air Quality Surveillance.

2.1 Monitoring Site, Equipment, and Quality Assurance Procedure

An extensive monitoring network was established in the Morenci area with sufficient spatial and temporal 

coverage to comprehensively evaluate the ambient impact of smelter emissions. In 1969, the Arizona 

Department of Health, Division of Air Pollution Control (ADH), began monitoring ambient SO2 air 

quality in Arizona. ADH established eight coulometric SO2 monitors around the seven-smelter towns in 

Arizona, including one in Clifton between October 1, 1969 and December 31, 1969.

15

Phelps Dodge began ambient SO2 monitoring at its Morenci smelter facility in 1974. The facility 

operated coulometric monitors at both stationary and mobile sites. During that same year, the State 

established two monitoring sites in the same area. The sites were coulometric monitors, but by 1984, 

both had been replaced with a pulsed fluorescent type. 

All monitors owned and operated by PDMI in the area of the Morenci smelter were deactivated when 

they ceased operations in December 31, 1984. Both State sites were deactivated after the smelter closed

in 1985. From 1986 to the present, no ambient SO2 monitors are operating in the Morenci area. 

Historic ambient SO2 monitoring sites and periods of operation are provided in Table 2.1 and 2.2. For a 

map of monitor locations and their proximity to the Morenci smelter, see Appendix A, Section A.2 of the 

2002 Maintenance Plan.

 

15 Arizona State Department of Health, Environmental Health Services, Division of Air Pollution Control, Sulfur 

Dioxide Monitoring Network Study, 1969. 
15

Table 2.1: State of Arizona Morenci SO2 Ambient Air Quality Monitors

Monitor Site Site Location ActivationDeactivation

Cadillac Point Latitude 33○05’20.1”N,Longitude 109○22’48.8”W 1974-1985

Stargo Latitude 33o04’17.6”N,Longitude 109○21’46.3”W 1974-1985

Table 2.2: Phelps Dodge Morenci SO2 Ambient Air Quality Stationary and Mobile Monitors

Monitor Site Site Location Activation -

Deactivation

Cadillac Point Latitude33○05'22.9"N, Longitude 

109○22'43.7"W

1976-1984

Fina Station Latitude33○03'14.3"N, Longitude 

109○18'59"W

1974 - 1984

Fairbanks Latitude33○02'10.19"N, 

Longitude 109○19'37.2"W

1976 - 1984

Metcalf Latitude33○06'47.1"N, Longitude 

109○22'25.2"W

1974 - 1984

Oroville Latitude33○05'28.6"N, Longitude 

109○18'25.2"W

1974 - 1981

Stargo Latitude 33○04'14"N, Longitude 

10921'44"W

1974 - 1984

Eagle Creek Latitude33○03'20.1"N, Longitude 

109○25'33.7"W

1974-1979

Mobile Monitors

Mobile-Standpipe Latitude33○02'58.8"N, Longitude 

109○23'9.9"W

1979-1984

Mobile-Center Market Latitude33○03'24.7"N, Longitude 

109○19'50.4"W

1979-1980

Mobile-Buena Vista Latitude33○03'25.8"N, Longitude 

109○19'59.3"W

1982-1984

Mobile-Lower Stargo Latitude33○03'55.5"N, Longitude 

109○21'20.5"W

1981-1984

Mobile-Newton Latitude33

○

04'33.1"N, Longitude 

109○21'19.8"W

1980-1982

Source: Air Quality Control for Arizona, Annual Report, Arizona Department of Health Services, 1974 –

1985.

2.2 SO2 Data Summary

Noted in previous section, ambient monitoring of the Phelps Dodge facility began in 1969. The highest 

number of recorded exceedances occurred in 1975, with concentrations between 219 to 237 micrograms 

per cubic meter (μg/m3) in the Clifton, Morenci area. Forty-nine exceedances of the SO2 24-hour average 

standard at PDMI were recorded in 1976 and the next highest number, 42 exceedances, occurred in 1982. 

In 1981, only five exceedances of the SO2 annual average standard were recorded. Monitoring data 

provided in Appendix D of the 2002 SIP indicates that the last recorded violation of either the 24-hour or 

annual SO2 NAAQS occurred in 1984. Throughout the history of the network, annual average SO2 levels 
16

were generally one-half of the 1971 NAAQS, which is about 0.030 ppm or 80 μg/m

3

.

16

Implementation of control measures and subsequent emissions reductions at the Morenci copper smelter 

area were reflected in reduced ambient SO2 concentrations beginning in the mid-1970s.

17

 Measured 

maximum concentrations at selected monitoring sites are presented in Appendix D, in the 2002 Morenci 

Sulfur Dioxide Nonattainment Area Plan, for the period 1979 through 1985. 

Due to the shutdown of the primary SO2 point source and termination of the monitoring network, 

redesignation of this area was completed according to Director John Seitz's October 18, 2000, 

Memorandum, Redesignation of Sulfur Dioxide Nonattainment Areas in the Absence of Monitored Data

(see Appendix B). As outlined in the guidance, redesignation did not require eight current consecutive 

quarters (two years) of quality-assured, violation-free data. The policy also exempts the Morenci area 

from maintenance plan requirements for continued monitoring within the area. The maintenance plan 

should include commitments to resume ambient monitoring before any major source of SOx emissions 

commences operation. In the event any new major point source begins operations in the area, new 

monitors will be installed to ensure continued attainment. For more information on historical monitoring 

information, see the 2002 Morenci Sulfur Dioxide Nonattainment Area State Implementation and 

Maintenance Plan. 

 

16 See Arizona Department of Health Services, Bureau of Air Quality Control annual reports 1970 through 1985, 

EPA Air Quality System annual summary reports, and Appendix D of the 2002 SIP.

17 See Chapter 2 of the 2002 SIP.
17

3.0 EMISSIONS INVENTORIES AND PROJECTIONS TO 2030

The current boundaries of the Morenci SO2 planning area lie solely within Greenlee County. However, 

the maintenance demonstration takes into consideration emissions sources within a 50 km buffer around 

the boundaries of the maintenance area. The 50 km buffer includes southern portions of Apache County, 

eastern portions of Graham County and the western parts of three New Mexico counties: Hidalgo, Grant 

and Catron. The nonattainment area and 50km buffer are illustrated in Figure 3.1.

The Seitz Memo, Redesignation of Sulfur Dioxide Nonattainment Areas in the Absence of Monitored 

Data on October 18, 2002, lists three required inventories in the maintenance plan: an emissions 

inventory representing actual emissions when violations occurred; an inventory representing current 

actual and allowable (or potential) emissions; and an inventory that projects allowable (or potential) 

emissions to the tenth year after redesignation. The guidance further advises, "the inventories should 

display emissions from each point source of SO2, with explanations of significant emissions changes, 

including source shutdowns." In addition to the inclusive (point, area, and mobile) Morenci Planning 

Area inventories, the inventory should include emissions from all SO2 point sources within a 50 km range 

of the planning area. The following inventories were included in the 2002 maintenance plan.

 Year 1980-1984 Inventory. This inventory characterizes emissions at 

the time the Morenci smelter was still operating and monitored violations 

of the NAAQS were occurring.

 Year 1990-1999 Inventory. The 1999 inventory represents the 

“current” or “attainment inventory” following the closure of the Morenci 

smelter. 

 Projected Year 2015 Inventory. The 2002 plan included a future 2015 

inventory to demonstrate, through dispersion modeling, emissions would 

remain at a level sufficient to maintain the NAAQS.

This SIP revision demonstrates continued attainment of the NAAQS for a second maintenance period 

through 2030. In addition to the historical inventories listed above, which are included in Section 3.1 for 

context, updates to current and projected emissions are provided in Sections 3.2 and 3.3 as follows. 

 Year 2011 Inventory. The 2011 inventory is the updated “current”

inventory. 

 Year 2015-2030 (Projected Inventory). The 2002 plan projected 

emissions for the first maintenance period, through 2015. This document 

includes inventory projections of total emissions for the Planning Area 

and 50 km point source emissions through the second maintenance 

period or 2030. Continued maintenance of the NAAQS through the 

second maintenance period is demonstrated, in part, by showing that 

future emissions of SO2 are expected to remain well below levels during 

the time when violations of the NAAQS were occurring. 
18

3.1 Emissions Inventories (Historical)

Sections 3.1 through 3.2 describe historical emissions sources and rates for the Morenci Planning Area.

The 1984 inventory reflects emissions during the last year of smelter operations. The 1999 inventory was 

the baseline year for the 2002 maintenance plan submittal, which shows emissions after the closer of the 

smelter. 

3.1.1 Point Sources

During its operation and until its closure on December 31, 1984, the Morenci primary copper smelter was 

the only major SO2 point source in the area. Smelting and refining of copper ore at Morenci’s primary 

copper smelter operations produced copper anode for further refining and sale to customers. The Morenci

smelter’s last full years of operation were 1983 and 1984. 

Table 3.1: Total Historical Potential to Emit and Actual Emissions in tons for years 1984 and 1999

In Nonattainment area 1984 1999

Potential to Emit (tpy) 297,110.00 (Allowable) 123.533

Actual Emissions (tpy) 82,432.00 0.390 

Within 50km Buffer 1984 1999

Potential to Emit (tpy) Unavailable 186.533

Actual Emissions (tpy) Unavailable 1.218

3.1.2 Area and Mobile Sources 

Area and mobile source emissions estimates for the Morenci Planning Area were derived from EPA’s 

AIR Data for 1999 for Greenlee County and 1984 emissions were derived from the prior 2002 SIP 

submittal. In the Morenci Planning area, SO2 emissions from mobile and area sources were 

approximately 31 tons in 1999. Area source emissions estimates did not include wildfire emissions. 

Detailed information on population levels and the methodology used to calculate area and mobile source 

emissions are contained in the 2002 SIP, Appendix C.4.

Table 3.2: Historical Greenlee County and Morenci Area and Mobile Source Emissions in tons

 

18 There was no data available for 1984, therefore, 1980 data is used to estimate 1984 emissions. 

Area 1984 1999

Greenlee County Unavailable 56

Morenci Planning Area 5918 31
19

3.2 2011 Emissions Inventory (Current) 

Year 2011was selected as the base year for this maintenance plan for consistency with the most recently 

available National Emissions Inventory data as well as data from the Arizona Department of 

Environmental Quality (ADEQ) updated Industrial point source inventory. The source categories covered 

in the emissions inventory include:

 Non-road Mobile (exhaust) sources

 On-roads Mobile (exhaust) sources

 Industrial (point) sources

 Area (non-point) sources

3.2.1 Point Sources

Since 2011, two permitted point sources were located within the Morenci Planning Area and 7 sources of 

SO2 emissions were located within the 50 km buffer.

The Phelps Dodge copper smelter was permanently closed in 1984; however, mining operations continue

under Freeport McMoRan. Mining operations accounted for the highest emission rates in 2011 from 

point sources, at 48.5 tons per year (tpy), with a potential to emit of approximately 87.6 tpy. The Morenci 

Townsite emergency generators accounted for 0.003 tpy of emissions with a potential to emit of 4.90 tpy. 

Table 3.3 illustrates the two major point sources in the planning area for 2011. Total emissions generated 

for 2011 is 48.532 tpy with a combined potential to emit of 92.50 tpy. 

Table 3.3: SO2 Point Sources within Morenci Planning Area

Source 2011

(tons/yr)

PTE

(tons/yr)

Freeport-McMoran Morenci, Inc. 48.529 87.60

Morenci Townsite WWTP Emergency Generators 0.003 4.90

Total Emissions 48.532 92.50

Data Source: Arizona Department of Environmental Quality (ADEQ) and 2011

NEI

In 2011, there were thirteen point sources located within 50 km, outside of the boundaries for the Morenci 

planning area. Table 3.4 illustrates the actual and potential to emit from these facilities in 2011, 38.03 tpy 

and 167.38 tpy, respectively. 
20

Table 3.4: SO2 Point Sources within 50-km Buffer

Source Latitude Longitude 2011 Actual 

Emissions

(tons/yr.)

PTE

(tons/yr)

Permit 

Status as of

2014

Arizona State 

Prisons - Safford 

Complex

32.8289 -109.565 0.193 4.96 Terminated

City of Safford –

Water Reclamation 

Plant

32.8424 -109.7241 0.214 24.26 Terminated

CKC Construction 

Company

32.8563 -109.6878 0.126 33.78 Active

Freeport McMoran 

Analytical Service 

Center

32.8165 -109.6482 0.002 0.39 Active

Freeport McMoran 

Corporation - Bee 

Canyon Well Field

33.3167 -109.4667 1.044 41.4 Active

Freeport McMoran 

Corporation - Mud 

Springs Well Field

33.3833 -109.4833 1.087 36.48 Active

Freeport-McMoran 

Safford Inc.

32.9473 -109.6509 35 81.2 Active

Glenbar Gin, Inc. 32.9839 -109.8567 0.0012 0.02 Active

Level 3 

Communications

32.8351 -109.7081 - 0.21 Terminated

Mt. Graham 

Regional Medical 

Center, Inc.

32.8228 -109.7352 0.09 2.804 Terminated

Select Cleaners 32.8327 -109.7161 0.001 0.163 Terminated

Tri County 

Materials-Hot Mix 

Asphalt Plant

32.8021 -109.7077 0.155 22.22 Active

USDOJFCI-Safford 32.7667 -109.7167 0.122 24.27 Terminated

Total Emissions 38.05 167.38

Data Source: Arizona Department of Environmental Quality (ADEQ) and the 2011 NEI
21

Figure 3.1: Morenci Sulfur Dioxide Planning Area and 50 km Buffer Area Point Sources
22

3.2.2 Totals for Mobile, Area and Point Sources

Current emissions estimates for area and mobile sources are derived from EPA’s 2011 National 

Emissions Inventory data.

19 Certified emissions data were scaled to the Morenci area using a population 

ratio or an area adjustment ratio to that of Greenlee County. Please note that 2011 area emissions 

estimates include wildfire emissions, which accounts for the large difference between the 1999 and 2011 

area source inventories. Wildfire emissions account for 91.43% of total cumulative emissions.

For more information on the calculations, see the emissions inventory data in Appendix C

Table 3.5 illustrates area and mobile source emissions for the Morenci planning area. The source 

categories include on-road mobile, non-road mobile, and area (non-point) sources. The largest source of 

emissions comes from area sources at 525.67 tpy, which includes wildfire emissions. Point area sources 

account for 48.532 tpy. The total SO2 emissions from all these categories are 574.882 tpy. The largest 

source of emissions is area (Non-point) sources contributing most of the emissions at 525.94 tpy. 

Table 3.5: Total SO2 Emissions for the Morenci Planning Area-2011

Source Type (tons per year)

On-Road Mobile 0.33

Non-Road Vehicle 0.08

Point (Industrial) 48.54

Area (Non-point) Sources 525.94

Total 574.89

3.3 Emissions Projections 

Sections 3.3.1 and 3.3.2 contain point, area, and mobile source emissions projected through the year 2030. 

Emissions are projected to ensure compliance with the NAAQS. Difficulties surrounding changes in 

economic growth, emissions control measures, capital turnover, fuel switching, and technological change 

make projections hard to estimate, therefore, a conservative forecasting approach was applied to the 

projections. Conservative forecasting included years 2010 to 2035 and is based on potential to emit. 

3.3.1 Point Source Projections 

Projecting future SO2 emissions is problematic due to many factors and uncertainties. Arizona does not 

anticipate any substantial increase in existing point source emissions between 2011 and 2030, for the 

planning area. New point sources or upgrades to existing sources of SO2 will be subject to review 

through ADEQ’s Permitting Program. 

3.3.2 Point Source Projections

Emissions projections are conservatively based on potential to emit (PTE) and point source emissions are 

assumed to remain constant at maximum permitted levels. With the permanent closure of the Morenci 

smelter, no major point sources exist in the Planning Area or within 50 km of its boundary. Total 

emissions as illustrated in Table 3.6 shows point source emissions within the planning area totaling 87.60 

 

19 EPA’s 2008 National Emission Inventory, Version 1.5 (released May 16, 2011) was the most recent available 

data at the time of drafting.
23

tons of emissions to 2030. Total emissions as illustrated in Table 3.7 shows projected emissions 

estimates are 201.88 tons to 2030. Combined total emissions for planning and 50km buffer area total 

289.48 tons of emissions to 2030. 

Table 3.6: Point Source Projections in Planning Area to 2030

Source 

Category

2011

(actuals)

2011

(pte)

2015

(pte)

2020

(pte)

2025

(pte)

2030

(pte)

Freeport 

McMoran

48.529 87.60 87.60 87.60 87.60 87.60

Morenci 

Townsite 

WWTP

Emergency 

Generators

0.003 4.90 - - - -

Total 

Emissions

48.532 92.50 87.60 87.60 87.60 87.60

Note; Symbol (-) indicates that permit has been terminated.

Table 3.7: Point Source Projections within the 50km Buffer Area

Source 

Category

2011

(actuals)

2011

(pte)

2015

(pte)

2020

(pte)

2025

(pte)

2030

(pte)

CKC 

Construction 

Company

0.126 33.78 33.78 33.78 33.78 33.78

Freeport 

McMoran 

Analytical 

Service Center

0.002 0.39 0.39 0.39 0.39 0.39

Freeport 

McMoran 

Corporation -

Bee Canyon 

Well Field

1.044 41.4 41.4 41.4 41.4 41.4

Freeport 

McMoran 

Corporation -

Mud Springs 

Well Field

1.087 36.48 36.48 36.48 36.48 36.48

FreeportMcMoran 

Safford Inc.

35 81.2 81.2 81.2 81.2 81.2

Glenbar Gin, 

Inc.

0.0012 0.02 0.02 0.02 0.02 0.02

Tri Country 

Materials-Hot 

Mix Asphalt 

Plant

0.155 22.22 8.61 8.61 8.61 8.61

Total Emissions 37.4152 215.49 201.88 201.88 201.88 201.88
24

3.3.2 Area, Mobile, Point Source Projections

ADEQ projects that SO2 emissions from area and mobile sources will grow proportionately with the 

population of the Planning Area. Appendix D describes the source category emissions and derivation of 

mobile and area source emissions estimates for the Morenci area in detail. 

Table 3.8 contains area and mobile source emissions projections for the Morenci Planning Area through 

2030. Actual emissions for 2011 total 574.89 tpy and projections total 613.96 tpy based on PTE.

Table 3.8: Area and Mobile Sources SO2 Emissions Projections for the Morenci Planning Area

Source Type 2011

(tpy)

2015

(tpy)

2020

(tpy)

2025

(tpy)

2030

(tpy)

On-Road Vehicle Sources 0.33 0.30 0.30 0.31 0.33

Non-Road Vehicle Sources(Locomotives and 

Aircraft)

0.05 0.05 0.05 0.05 0.05

Non-Road Vehicle Sources (Other) 0.03 0.03 0.03 0.03 0.03

Industrial (point) Sources 48.54 87.60 87.60 87.60 87.60

Area(Non-point) Sources (Fires) 525.67 525.67 525.67 525.67 525.67

Area (Non-point) Sources (Other) 0.27 0.27 0.27 0.28 0.28

Total Emissions 574.89 613.92 613.92 613.94 613.96
25

4.0 CONTROL MEASURES

Sections 4.1 and 4.2 describe SO2 emission control measures for sources within the Morenci Planning

Area and point sources located within the 50 km buffer zone of the Planning Area.

4.1 Point Sources

Nonattainment area plans are required to provide for the implementation of all reasonably available 

control measures (RACMs) including reductions in emissions from existing sources in the area that may 

be obtained through reasonably available control technology (RACT). RACT is the emissions control 

level for sources located in SO2 nonattainment areas. RACT is determined, in part, by the technological 

and economic feasibility of the control for the specific source and is generally defined for SO2 as control 

technology which will achieve the NAAQS within statutory timeframes.20 Maintenance plans should 

ensure that the level of control that allowed the area to reach attainment continues in the future. 

Morenci Copper Smelter

The PDMI smelter was subject to all requirements in R18-2-715.01 (A)-(T), which define, “Standards of 

Performance for Existing Primary Copper Smelters; Compliance and Monitoring” and the January 14, 

1986, compliance date for the provisions of this rule, in accordance with R18-2-715.01. Compliance was 

achieved when Phelps Dodge permanently closed the copper smelter on December 31, 1984. 

Closure of the copper smelter in 1984 resulted in SO2 emission reductions in 1985 of at least 46,012 tpy, 

based on permitted SO2 stack emission limits effective for PDMI, January 1, 1985. The permanent 

shutdown of the smelter reduced total emissions in the Planning Area to less than 0.1% of pre-closure 

levels, which meets RACT requirements. 

Existing Point Sources

There are currently eight active sources located within the planning area and the 50 km buffer zone. There 

is two point sources located in the Morenci planning area. There are thirteen point-sources that exist in the 

50km buffer zone, details of these facilities are discussed below. 

ADEQ issues permits point sources within the planning area. The seven other point sources within the 

50km buffer are also permitted by ADEQ. Permit limits combined emissions to 87.60 tons per year for 

the planning area point sources and less than 201.88 tons per year for the buffer area point sources. In the 

event a new source moves into the area, or any modifications are made to an existing source, they will be 

subject to ADEQ’s permitting and monitoring requirements. 

4.2 Area and Mobile Sources

Emissions data reflect that SO2 from area and mobile sources in the Morenci planning area account for 

approximately 13% of the total area and mobile source emissions in Greenlee County. In 2011 on-road 

and non-road mobile emissions totaled 0.41 tons. Area sources total 525.94 tons. Of the area source total 

522.95 tons were due to wildfires, more than 99% of area source emissions. ADEQ predicts nominal 

growth in SO2 emissions for the area through 2030. 

 

20 U.S. EPA, Office of Air and Radiation, Office of Air Quality Planning and Standards, SO2 Guideline Document, 

February 1994.
26

Several EPA programs are related to the sulfur content of fuels. These programs integrate engine and fuel 

controls for emissions reductions in highway vehicles and non-road equipment. Due to these national 

programs, future sulfur emissions are likely to be lower than those projected in Chapter 4 of this 

document. The programs are as follows: 

1) Tier 2 Vehicle and Gasoline Sulfur Program for passenger vehicles,

2) Tier 3 Vehicle and Gasoline Sulfur Program for passenger vehicles, 

3) Heavy-Duty Engine and Vehicle Standards and Highway Diesel Fuel Sulfur Control 

Requirements for highway trucks and buses, and

4) Clean Air Non-road Diesel Rule for non-road diesel equipment.

EPA’s Tier 2 program, begun in 2004, implements more stringent emissions standards for the reduction 

of oxides of nitrogen emissions from all passenger cars and light trucks. To meet the new emission 

standards the program incorporates gasoline requirements that substantially reduce sulfur levels in 

gasoline. Sulfur in fuel impairs the effectiveness of vehicle emission control systems and by removing 

most of the sulfur from gasoline, new emission controls work longer and more efficiently. As a result, the 

standards reduce the average national sulfur content of gasoline by up to 90%. 

EPA’s Tier 3 program per FR Vol 79 No 81 published on April 28, 2014, establishes more stringent 

vehicle emissions standards and will reduce the sulfur content of gasoline beginning in 2017, as part of a 

systems approach to addressing the impacts of motor vehicles and fuels on air quality and public health. 

The gasoline sulfur standard will make emission control systems more effective for both existing and new 

vehicles, and will enable more stringent vehicle emissions standards. The vehicle standards will reduce 

both tailpipe and evaporative emissions from passenger cars, light-duty trucks, medium-duty passenger 

vehicles, and some heavy-duty vehicles. This will result in significant reductions in pollutants such as 

ozone, particulate matter, and air toxics across the country and help state and local agencies in their 

efforts to attain and maintain health-based National Ambient Air Quality Standards.21

The 2007 Heavy-Duty Engine and Vehicle standards and Highway Diesel Fuel Sulfur Control program 

established new oxides of nitrogen and particulate matter emissions standards for heavy-duty highway 

engines and vehicles. The standards are based on high-efficiency catalytic exhaust emission control 

technologies. Because emissions control devices are damaged by sulfur, associated regulations reduce the 

sulfur in highway diesel fuel by 97%.

The Clean Air Non-road Diesel Rule established new oxides of nitrogen and particulate matter emission 

standards that are applicable to diesel engines used in construction, agricultural, industrial, and other 

equipment. To prevent damage to emissions control systems, the regulations also require a reduction in 

sulfur levels in non-road diesel fuel from the current approximately 3,000 parts per million to 15 parts per 

million when fully implemented. Fuel sulfur reductions are being phased in over a number of years 

beginning in 2007.

 

21 To see more information regarding EPA’s tier program see: http://www.epa.gov/otaq/tier3.html.
27

5.0 MODELING DEMONSTRATION

Chapter 5.0 provides an overview of EPA’s and ADEQ’s modeling demonstration that was conducted for 

the Morenci Planning Area.

5.1 Historical Modeling Analysis

On June 21, 2002, ADEQ submitted to EPA the “Morenci Sulfur Dioxide Nonattainment Area State 

Implementation and Maintenance Plan” with a request to approve the plan and redesignate the area to 

attainment for the 1971 primary SO2 NAAQS. As part of its final rulemaking for the plan, EPA 

conducted an analysis on the plan based on the October 18, 2000, Memorandum from Director John Seitz 

to the Regional Office Air Division Directors, “Redesignation of Sulfur Dioxide Nonattainment Areas in 

the Absence of Monitored Data.” The Seitz memo provides guidance for redesignation to attainment in 

those situations where major point sources are no longer in operation and in the absence of monitoring 

data. Results of EPA’s analysis are contained in the “Technical Support Document for Notice of Direct 

Final Rulemaking on Sulfur Dioxide (SO2) Redesignation Request and Maintenance Plan for Morenci, 

Arizona, March 2004.” An overview of the historical dispersion modeling analysis is provided below.

22

Phelps Dodge Morenci, Inc permanently closed the smelter on December 31, 1984, and dismantled the 

facility by December 1996. The area remains sparsely settled and there has been no significant 

population growth. There are some industrial and commercial activities, estimated emissions are located 

in Chapter 3.0. There are no significant sources and past violations were attributed to emissions from the 

smelter, which is no longer in existence. Emissions of SO2 from other sources have not significantly 

changed since the closure of the smelter.

Using the criteria established in the Seitz memo, EPA conducted screen modeling to show that the nonsmelter sources were insignificant and the smelter was the dominant source, which contributed to high 

SO2 concentrations 

During the last maintenance plan submission the two largest sources in the 50-kilometer buffer area were, 

Other sources including several cotton gins and a prison had projected PTE ranging from .01 to .47 tons 

per year for 2015. No other sources were modeled due to their low output of emissions and because they 

were outside of the planning area. EPA determined that the ambient SO2 projection requirement for 

redesignations and maintenance requirements were satisfied.

23

5.2 Current Modeling Demonstration 

For this second maintenance plan, ADEQ conducted a modeling analysis similar to EPA’s where the two 

largest sources in the Maintenance Area or within the 50km buffer were modeled. The FreeportMcMoRan Morenci Mine (FMMM) is located within the Maintenance Area and has a potential to emit

(PTE) of 88 tons/year (tpy). The Freeport-McMoRan Safford Mine (FMSM) is located within the 50 km 

buffer and has a PTE of 81 tpy. No other point sources were modeled because of their low or negligible 

emissions. Inspection of the individual point sources indicates many are emergency generators with 

actual emissions less than one tpy and therefore considered negligible.

 

22 For more information, see “Technical Support Document for Notice of Direct Final Rulemaking on Sulfur 

Dioxide (SO2) Redesignation Request and Maintenance Plan for Morenci, Arizona” Air Division U.S. 

Environmental Protection Agency, Region at: http://www.epa.gov/region9/air/az/morenci/tsd0415.pdf.

23 IBID
28

Using the data from the two facilities, ADEQ projected emissions to 2030 (based on PTE/maximum 

allowable emissions). The results show that low levels of point source emissions are expected to persist 

through the second maintenance period. State and local permitting programs will protect the attainment 

status of the area for any future sources that may operate nearby. Details of the NSR/PSD program are 

discussed in chapter 6. 

ADEQ issued renewal permits to FMSM and FMMM in February 2012 and October 2013. Table 5.1 

summarizes the PTE of SO2 emissions for FMSM and FMMM based on the two renewal permits and 

shows that there is no change in total SO2 emission limits for both facilities. 

Table 5.1: Emissions of SO2 for FMMM and FMSM in Renewal Permits

Facility 

PTE in renewal permits (tpy) Modeled Emission (tpy)

Point Fugitive Total Point Fugitive Total 

FMMM 0.8 86.8 87.6 0.78 86.75 87.5

FMSM 50 31 81 50.02 31.03 81.05

The standard EPA screening dispersion model, AERSCREEN (version 11126) was used to estimate the 

impact of SO2 sources in or near the Morenci nonattainment area. AERSCREEN is the screening version 

of AERMOD, EPA’s preferred model for near-field dispersion. AERSCREEN generates estimates of 

“worst-case” 1-hour concentrations for a single source, without the need for hourly meteorological data, 

and also includes conversion factors to estimate “worst-case” 3-hour, 8-hour, 24-hour, and annual 

concentrations. AERSCREEN is intended to produce concentration estimates that are equal to or greater 

than the estimates produced by AERMOD with a fully developed set of meteorological and terrain data. 

According to an EPA memorandum dated April 11, 2011, AERSCREEN has replaced SCREEN3 as the 

recommended screening model. 24

The AERSCREEN model consists of two main components: 1) the MAKEMET program; and 2) the 

AERSCREEN command-prompt interface program. The MAKEMET program generates applicationspecific worst-case meteorology using representative ambient air temperatures, minimum wind speed, and 

site-specific surface characteristics (albedo, Bowen ratio, and surface roughness obtained with the 

AERSURFACE tool). The AERSCREEN program interfaces with AERMAP (terrain processor in 

AERMOD) and BPIPPRM (building downwash tool in AERMOD) to process terrain and building 

information respectively, and interfaces with the AERMOD model utilizing the SCREEN option to 

perform the modeling runs. 

An initial modeling analysis was performed in 2012 using AERSCREEN version 11126, which is still the 

most recent version of AERSCREEN. However, the AERSURFACE version (version 08009) used in the 

2012 analysis has been updated to the new version 13016. A test run, performed in 2014, indicates that 

the two versions generated identical surface characteristic parameters. 

Another issue, is related to the terrain data. The 2012 analysis used Digital Elevation Model (DEM) data, 

which are no longer updated by the USGS. Instead, National Elevation Dataset (NED) data are being 

actively supported and checked for quality. Therefore, NED represents a more up-to-date and improved 

 

24 According to the EPA’s memorandum dated April 11, 2011, titled “AERSCREEN Released as the EPA 

Recommended Screening Model”; AERSCREEN has replaced SCREEN3 as the recommended preferred model. 
29

resource for terrain elevations for regulatory modeling purposes. In order to address this issue, a test run 

was performed to compare modeled concentrations from the FMMM’s blasting emissions by using the 

DEM data vs. the NED data. The results show that the modeled concentrations based on the DEM data 

and the NED data are nearly identical (150.6 μg/m3 vs. 150.2 μg/m3 for 24-hour SO2). 

Based on the discussions above, it is concluded that the 2012 modeling analysis is still valid and no 

updates are needed. Further details of the modeling analysis are included in Appendix D.

Table 5.2 and 5.3 present the cumulative impact of the FMMM and FMSM facilities on the Morenci 

Maintenance Area and at the boundary of the Maintenance Area. The modeling results are shown in 

micrograms per cubic meter (μg/m3) for comparison to the 1971 primary 24-hour and annual SO2

NAAQS. The modeling demonstrates that these sources will not cause a violation of the 1971 primary 

SO2 NAAQS

Table 5.2: Cumulative Impacts of FMMM and FMSM on the Morenci Maintenance Area

Facility Average

Max. impact 

on Morenci 

maintenance 

area (μg/m3)

Total 

modeled 

conc. 

Backgroun

d conc. 

(μg/m3)

Total

conc. 

(μg/m3)

NAAQS 

(μg/m3)

% 

Standard

FMMM 24-hour 151.5 171.5 20 191.5 365 53% FMSM 20

FMMM Annual 25.3 28.6 5 33.6 80 42 % FMSM 3.3

Table 5.3: Cumulative Impacts of FMMM and FMSM on the Morenci Maintenance Area 

Boundary

Facility Average

Max. impact 

on Morenci 

maintenance 

area 

boundary 

(μg/m3)

Total 

modeled 

conc. 

Background 

conc. 

(μg/m3)

Total 

conc. 

(μg/m3)

NAAQS 

(μg/m3)

% 

Standard

FMMM 24-hour 20 40 20 60 365 16% FMSM 20

FMMM Annual 3.3 6.6 5 11.6 80 15 % FMSM 3.3
30

6.0 MAINTENANCE PLAN SUMMARY

Section 107(d)(3) of the CAA requires that nonattainment areas have a fully approved maintenance plan 

meeting the requirements of Section 175A before they can be redesignated to attainment. Section 175A 

also requires submittal of a SIP revision that provides for maintenance of the NAAQS for at least 10 years 

after the redesignation to attainment. A subsequent SIP revision providing for maintenance of the 

NAAQS for an additional 10 years is due eight years into the first ten-year maintenance period. 

This section addresses the core provisions for maintenances plans as recommended in the September 4, 

1992, Memorandum, “Procedures for Processing Requests to Redesignate Areas to Attainment”. 

Additional guidance applicable to the Morenci Planning Area is contained in the October 18, 2000, 

Memorandum, “Redesignation of Sulfur Dioxide Nonattainment Areas in the Absence of Monitored 

Data”, regarding individual components of maintenance demonstrations for areas where historic 

violations of the NAAQS were caused by sources that are no longer operating. 

6.1 Emissions Inventories

According to the 1992 guidance, states should develop an attainment emissions inventory to identify the 

level of emissions in an area sufficient to attain a given NAAQS. The October 18, 2000, "Seitz guidance"

outlines three inventories that should be included in the maintenance plan: an inventory representing 

actual emissions during the period when violations of the NAAQS were occurring; an inventory 

representing current and allowable (or potential) emissions; and an inventory that projects allowable (or 

potential) emissions to the tenth year after redesignation. 

The 2002 SIP contained the recommended historical inventories; a 1984 inventory for the last full year of 

smelter operations and a 1999 post-smelter inventory; as well as projected point, area, and mobile source 

emissions for the Morenci Planning Area and point source emissions within 50 km of the Planning Area 

through the first 10-year maintenance period (2015). Chapter 3 of this document includes a summary of 

these previously submitted inventories, an updated 2011 "current" inventory, and projected emissions 

through 2030. 

6.2 Maintenance Demonstration

Maintenance plans should provide a demonstration that future emissions of SO2 will not cause a violation 

of the NAAQS. Figure 6.1 shows historical emissions based on point sources, current and projected 

emissions are totals from all sectors, which illustrates continued attainment. This SIP revision 

demonstrates the level of emissions in the Morenci area will remain well below those that occurred during 

the period of recorded ambient SO2 NAAQS violations. Projected emissions and the results of the 

dispersion modeling analysis contained in Chapter 5 both demonstrate that the Morenci area will continue 

to maintain the 1971 primary SO2 NAAQS. 
31

Figure 6.1: SO2 Emissions for Years 1984-2030

The emissions inventories for the Planning Area and 50 km buffer demonstrate a stringent level of 

protection of ambient air quality (see Chapter 5), the permanent and enforceable emissions reductions due 

to the closure of the Morenci smelter are greater than needed to attain and maintain the NAAQS. 

Therefore, the area is expected to continue to exhibit a substantial margin of safety that is protective of 

the 1971 SO2 NAAQS.

6.3 Ambient Monitoring 

Once an area is redesignated to attainment, continued operation of an appropriate air quality monitoring

network is generally required to verify the attainment status of the area. In the Morenci area historic 

violations were caused by a major point source of SO2 emissions that is no longer in operation and 

ambient SO2 monitors were removed immediately following the shutdown of the emissions source. In 

such cases, the October 18, 2000, Seitz Memorandum, “Redesignation of Sulfur Dioxide Nonattainment 

Areas in the Absence of Monitored Data,” exempts these areas from requirements for continued ambient 

monitoring. The maintenance plan, however, should include commitments to resume ambient monitoring 

before any major source of SO2 emissions commences operations.

ADEQ will continue to demonstrate maintenance of the SO2 NAAQS through updates to the emissions 

inventory. In addition, ADEQ commits to reestablish an appropriate ambient monitoring network before 

any major source of SO2 begins operations in the Morenci Planning Area. 

6.4 Verification of Continued Attainment

The state is required to provide assurance that it has the legal authority necessary to implement and 

enforce all necessary measures used to attain and maintain the NAAQS and include an indication of how 

it will track the progress of the maintenance plan.

ADEQ anticipates no relaxation of any implemented control measures used to attain and maintain the 

0.00

10,000.00

20,000.00

30,000.00

40,000.00

50,000.00

60,000.00

70,000.00

80,000.00

90,000.00

1984 2011 2015 2020 2025 2030

Tons of SO2

Years

SO2 Emissions
32

ambient air quality standards. ADEQ commits to submit to EPA Region 9 any changes to rules or 

emission limits applicable to SO2 sources as a SIP revision. ADEQ also commits to maintain the 

necessary resources to actively enforce any violations of the provisions contained in this submittal. 

Emissions reductions sufficient to meet the NAAQS were accomplished due to the permanent closure of 

the primary source of SO2 emissions in the area, the Morenci copper smelter. Freeport-McMoRan 

Copper & Gold Inc. (successor to Phelps Dodge, owner and operator of the defunct Morenci copper

smelter) does not currently hold an active permit, and no subsequent Title V permit application has been 

submitted to ADEQ for this closed facility. The smelting facility cannot rebuild and reopen without 

submittal of a New Source Review (NSR) and Title V (Part 70) permit application according to Arizona 

Revised Statutes (ARS) 49-426 and Arizona Administrative Code, Title 18, Chapter 2, Article 4, Permit 

Requirements for New Major Sources and Major Modifications to Existing Major Sources. The emission 

reductions achieved following the closure of this facility are both permanent and enforceable. 

Further, any new major sources or major modifications to existing point sources of SO2 are subject to the 

new source permitting procedures contained in AAC Title 18, Chapter 2, Article 4, specifically, ADEQ’s 

Prevention of Significant Deterioration (PSD) Permitting Program contained in AAC R18-2-406. These 

regulations were established to preserve the air quality in areas where ambient concentrations are below 

the NAAQS and require stationary sources to undergo preconstruction review, utilizing Best Available 

Control Technology (BACT), before the facility is constructed, modified, or reconstructed. 

In general, State permitting programs for major and minor sources are contained in Arizona 

Administrative Code Title 18, Chapter 2, Articles 3 and 4.

25 Although the Morenci Mainteinance Area is 

located entirely within the Arizona state boundary, a portion of the 50 km buffer area extends into New 

Mexico. The New Mexico Environment Department, Air Quality Bureau has a permitting program for 

sources constructing within their jurisdiction; not including Bernalillo County and tribal lands. 

Maintenance of the SO2 NAAQS in the Morenci area will be tracked through updates to the emissions 

inventory and permit applications received for SO2 emitting sources. Any permitted sources are subject 

to the monitoring, reporting, and certification procedures contained in AAC R18-2-306 and AAC R18-2-

309 respectively. ADEQ has authority pursuant to ARS § 49-101 et seq. to monitor and ensure source 

compliance with all applicable rules and permit conditions for sources in its jurisdiction. 

6.5 Contingency Plan

Contingency plans should contain measures to correct any violation of the NAAQS that occurs after 

redesignation. According to the 1992 guidance Procedures for Processing Requests to Redesignate Areas 

to Attainment, the contingency plan must require, at a minimum, implementation of all measures 

contained in the Part D nonattainment plan for the area prior to redesignation. 

The only threat to the 1971 SO2 NAAQS in this Planning Area would be from new sources. Because the 

primary source of SO2 emissions in the Morenci area permanently closed, measures to ensure continued 

attainment of the SO2 NAAQS are PSD and permitting requirements. As noted in Section 6.4, any new

 

25 ADEQ implements a SIP approved PSD program for all regulated NSR pollutants except for PM10 and 

greenhouse gases (GHGs). For PM10 and GHGs, ADEQ implements the Federal PSD program in 40 CFR § 52.21 

pursuant to delegation agreements with EPA. A proposed State Implementation Plan revision was submitted to EPA 

on April 10, 2012, to bring the Arizona SIP for areas under the jurisdiction of ADEQ into compliance with the NSR 

and PSD requirements of CAA Section 110(a)(2)(C) and 40 C.F.R. Part 51, Subpart I, with the exception of the 

requirements pertaining to GHGs. 
33

major source proposing to operate in the Morenci area is subject to the provisions of AAC R18-2-406, 

“Permit Requirements for Sources Located in Attainment and Unclassified Areas.” These programs

address New Source Review and PSD requirements applicable to SO2 sources.26 Under the PSD program 

stationary sources are required to undergo preconstruction review before the facility is constructed, 

modified, or reconstructed and to apply BACT. If a new source is not a major source it is required to 

obtain a permit under minor source permitting rules at AAC R18-2-Article 3. 

6.6 Conclusion

The Morenci Planning Area continues to meet the 1971, 24-hour and annual primary SO2 NAAQS. This 

submittal demonstrates that all of the essential regulatory elements have been met and the Morenci area

will maintain the 1971 primary SO2 NAAQS for an additional ten years, through year 2030. Maintenance 

of the NAAQS is demonstrated by the closure of the only significant source of SO2 emissions in the area, 

existing limits and controls on the remaining sources, and the requirement to impose PSD requirements 

on any new stationary sources. ADEQ requests that EPA approve this demonstration of maintenance 

through year 2030.

 

26 AAC R-18-2-403 “Permits for Sources Located in Nonattainment Areas” and R18-2-406 “Permit requirements for 

Sources Located in Attainment and Unclassifiable Areas” were adopted effective November 15, 1993, and most 

recently amended by final rulemaking at 18 A.A.R 1542, effective August 7, 2012. New Source Review standards 

are defined in 40 CFR § 51.307, Prevention of Significant Deterioration standards, in 40 CFR § 51.166.
Page Intentionally Left Blank
Appendix A

Procedures for Processing Requests to Redesignate Areas to Attainment, 

Memorandum, John Calcagni, Director, Air Quality Management Division, U.S. 

Environmental Protection Agency
Page Intentionally Left Blank
AIR PKOOnAl.!s BR.ANCi 

(@I UNITED STATES ENVIRONMENTAL PROTECTION AGE 

Office of Air·Quality Planning andSta'ldards 

Research Triangle Park. North Carolina 27711 

4 SEP 1992 

U . .J?nn f1 ~ SEP 8 1992 

.L!:b~ I 

I!IPM\BOIOlf IV 

ATLANTA. GA. 

MEMORANDUM 

SUBJECT: Procedures for processing 

to Attainment 

FROM: 

TO: 

Purpose 

John Calcagni, Directo~~~~ 

Air Quality Management 

Director, Air, Pestic' es and Toxics nt 

Division, Regions I and IV 

Director, Air and Waste Management Division, 

Region II 

Director, Air, Radiation and Toxics Division, 

Region III 

Director, Air and Radiation Division, 

Region V 

Director, Air, Pesticides and Toxics Division, 

Region VI 

Director, Air and Toxics Division, 

Regions VII, VIII,. IX, and X 

Areas 

The Office of Air Quality Planning and Standards (OAQPS) 

expects that a number of redesignation requests will be submitted 

in the near future. Thus, Regions will need to have guidance bn 

the applicable procedures for handling these requests, including 

maintenance plan provisions. This memorandum, therefore, I. 

consolidates the Environmental Protection Agency's (EPA!s) 

guidance regarding the processing of requests for redesignation 

of nonattainmentareas to attainment for ozone (03)' carbon I 

m(:moxide (<;:0)( particulate matter (PM-IO) .. ~ulfur dioxid~ (S02~' 

n~trogen d~ox~de (NO ), and lead (Pb). Reg~ons should useth~s 

guidance as a genera~ framework for drafting Federal Register I 

notices pertaining to redesignation requests. Special concerns 

for areas seeking redesignation from unclassifiable to attainment 

will be addressed on a case-by-case basis. 

Background 

Section l07(d) (3) (E) of the Clean Air Act·, as amended, 

states that an area can be redesignated to attainment if the 

following conditions are met: 
2 

1. The EPA has determined that the national ambient air 

quaE ty standards '( NMQS) have been attained. 

2.' The applicable implementation plan has been fully 

approved by EPA under section 110(k). 

3. The EPA has determined that the improvement in air 

quality is due::to permanent and enforceable reductions in . emissions. 

4. The state has met all applicable requirements for the 

area under section 110 and Part D. 

5. The EPA has fully approved a maintenance .. plan, including 

a contingency plan, for the area under section 175A. 

Each of these criteria is di~cussed in more detail in the 

following paragraphs. Particular attention is given to 

maintenance plan provisions at the end of this document since 

maintenance plans constitute a new requirement under the amended 

Clean Air Act. Exceptions to the guidance will' be considered on 

a case-by-case basis. . 

1. Attainment of the Standard 

The State must show that the area is attaining the 

applicable NAAQS. There are two components involved in making 

this demonstration which should be considered interdependently. 

The first component relies upon ambient air quality data. The 

data that are used to demonstrate attainment should be the 

product of ambient monitoring that is representative of the area 

of highest concentration. These monitors should remain at the 

same location for the duration of. the monitoring"period required for demonstrating attainment. The data should be collected and 

quality-assured in accordance with 40 CFR 58 and recorded in the 

Aerometric Information Retrieval System (AIRS) in order for it to 

be available to the public for review. For purposes of 

redesignation, the Regional Office. should verify that the 

integrity of the air quality monitoring network has been . preserved .. 

ForPM-lO, an area may be considered attaining the NAAQS if 

1:he.numberof expected exceedances per year, according to 40 CFR 

50.6, is less than or equal to 1. 0., For 03, the area must show 

that the average .. annual number of expected exceedances, according 

to 40 CFR 50.9, is less than or equal to 1.0 based on data from 

all monitoring sites in the area or its affected downwind' 

environs. In making this showing, both PM-10 and 0 3 must rely on 

3 complete,.,.consecutive. ·,calendar, .years. fof, .. quality.-assured".al·r" .. ,,, .. '"., 

quality monitoring data, collected' in accordance with 40 CFR 50, 

Appendices Hand K. For CO, an area may be considered attaining 

the NAAQS if there are no violations, as determined in accordance 
3 

with 40 CFR 50.8, based on 2 complete, consecutive calendar ye~rs 

of quality-assured monitoring data. For 5°2 , according to 40 CFR 

50.4; an area must show no more than· one exceedance annually and 

for Pb, ~ccording to section 50.12, an area may show no 

exceedances on a quarterly basis. 

The second component relies upon supplemental EPA-approved 

air quality modeling. No such supplemental modeling is required 

for 03 nonattainment areas seeking redesignation. Modeling may be necessary to determine the representativeness of'. the .moni tored 

data. For pollutants such as 502 and CO; a small number of I 

monitors typically is not representative of areawide air quality 

or areas ,of highest concentration. When dealing with S02' Pb'l 

PM-10 (except for a limited number of initial moderate , nonattainment areas), and CO (except moderate areas with design 

values of 12.7 parts per million or lower at the time of passage 

of the Clean Air Act Amendments of 1990), dispersion modeling I 

will generally be necessary to evaluate comprehensively sources' 

impacts and to' determine the areas of expected high ' '. I 

concentrations based upon current conditions. Areas which were 

designated nonattainment based on modeling will generally not be 

redesignated to attainment unless an acceptable modeling analysis 

indicates attainment. Regions should consult with OAQPS for· 

further guidance addressing the need for modeling in specific circumstances. . 

2. state Implementation Plan (SIP) Approval 

Thr SIP for the area must be fully approved under section 

l10(k), and must satisfy all requirements that apply to the 

area. It should be noted that approval action on SIP elements 

and the redesignation request may occur simultaneously., An area 

cannot be redesignated if a required element of its plan is the 

subject of a disapproval; a finding of failure to submit or tol 

implement the SIP; or ·partial, conditional, or limited approval. 

However, this does not mean that earlier issues with regard to 

the SIP will be reopened. Regions should not reconsider those 

things that have already been approved and for which the Clean 

Air Act Amendments did not alter what is required. In contrast, 

to the extent the Amendments add a requirement or alter an I 

existing. requirement so that it adds something more, Regions 

should consider those issues. In addition, requests from areas 

known to be affected by dispersion techniques which are 

inconsistent with EPA guidance will continue to be considered 

unapprovable under section 110 and will not qualify for 

redesignation. 

1section 110(k) contains the requirements for EPA ac'tion on 

plan submissions; It addresses completeness, deadlines, full and 

partial approval, conditional approval,'and disapproval. 
4 

3., Permanent and' Enforceable Improvement in Air Quality 

The State must be able to reasonably attribute the ' 

improvement in air quality to emission reductions which are 

permanent and enforceable. 2 Attainment resulting from temporary reductions iri emission rates (e.g., reduced production or 

shutdown due to temporary adverse economic,conditions) or , unusually favorable meteorology would not qualify as an air 

quality improvement due to permanent and enforceable emission 

r,eductions. " . 

In making this showing, the'State should'estimate the 

percent .reduction (from the year that was used to determine the 

design value for designation and classification) achieved,from 

Federal ,measures such as the Federal Motor Vehicle Control 

Program and fuel volatility rules as well as control measures 

that have been adopted and implemented by the' state. This , estimate should consider emission rates, production capacities, 

and other related information to clearly show that'the air, 

quality improvements are the result of implemented controls. The 

analysis should assume that sources are operating at permitted 

levels (or historic peak,levels),unless evidence is presented 

that such an assumption is unrealistic. 

4. Section,110 and Part P Requirements 

For the purposesof'redesignation, a'State must meet all 

requirements of section 110 and Part 0 that were applicable prior 

to submittal of the complete redesignation reque~t. When 

evaluating a redesignation request, Regions should not consider , whether the state has met requirements that come due und~r the 

Act after submittal of a complete redesignation request. , 

2This is consistent'with EPA's existing policy on 

redesignations as ,stated iri an April 21, 1983 memorandum titled 

"Section 107 Designation Policy Summary." This memorandum states 

that in order for an area to be redesignated to attainment, the 

state must show that "actual enforceable emission reductions are 

responsible for the recent air quality improvement." This 

element of the policy retains its validity under the. amended Act 

pursuant to section 193. [Note: other aspects of the April 21; 

1983 memorandum have since been superseded by subsequent memorandums~.interested parties should consult with OAQPS before 

relying on these aspects, e.g. those relating to required years 

of air quality data.] 

3under section 175A(C), however, the requirements of Part D remain·~in ' force .. and ,·eff ect . for·' the areaunt·i 1 'such "time" as it 'is' 

redesignated. Upon redesignation to attainment, the requirements 

that became due under section 175A(C) after submittal of the . complete redesignation request would no longer be applicable. 
;-i~:1~;~-~ .. :~" 

5 

However, any requirements that came due prior to sUbmittal of the 

redesignation request must be fully approved into the plan at o~ 

before the time EPA redesignates the area. 

To avoid confusion concerning what requirements will be 

applicable for purposes of redesignation, Regions should 

encourage states to work closely with the appropriate RegiQnal 

Office early in the process. This will help to ensure that a 

redesignation request submitted by the state has a high , likelihood of being approved by EPA. Regions 'sho~ld advise 

states of the practical planning consequences if EPA disapproves 

the redesignation request or if the request is invalidated, I 

because of violations recorded during EPA's review. ' Under such 

circumstances, EPA does not have the discretion to adjust" 

schedules for implementing SIP requirements. As a result, an 

area may risk sanct,ions and/or Federal implementation plan 

implementation that could result from failure to meet SIP 

submittal or implementation requirements. 

a. Section 110 Reguirements 

section 110(a)(2) contains general requirements 

nonattainment plans. Most of the provisions of this 

the same as those contained in the pre-amended Act. 

provide guidance on these requirements'as needed. 4 

b. Part P Reguirements 

for 

section 

We will 

are 

Part D consists of general requirements applicable to all 

areas which are designated nonattainment based on a violation of 

the NAAQS. The general requirements are followed by a series of 

subparts specific to each pollutant. The general requirem.ents I 

appear in subpart 1. The requirements relating to 0 3 , CO, PM-10, 

S02' N02' and Pb appear in subparts 2 through 5. In those 

instances where an area is subject to both the general 

nonattainment provisions in subpart 1 as well as one of the 

pollutant-specific subparts, the general provisions may'be 

subsumed within, or superseded by, the more specific requirements of subparts 2 through 5. ' 

If an area was not'classified under 'section 181 for '03, or 

section 186 for CO, then that area is only subject to the 

provisions of subpart 1, "Nonattainment Areas in General." In 

addition to relevant provisions in subpart 1~ an 03 and CO area, 

which is classified, must meet all applicable requ1rements in r 

subpart 2, "Additional Provisions for Ozone Nonattainment Areas," 

and subpart 3, "Additional Provisions for Carbon Monoxide 

4General guidance regarding the requirements for SIP'S may 

be found in the "General Preamble to Title I of the 1990 Clean 

Air Act Amendments,"57 FR 13498 (April 16, 1992). 
6 

Nonattainment"Areas," respectively, before the area may be rede~ignated to,attainment. All PM-lO nonattainment areas 

(whether classified a~ moderate or serious) must similarly meet 

the applicable general provisions of subpart 1 and the specific 

PM-10 provisions in subpart 4, '"'Additional Provisions for 

Particulate Matter Nonattainment Areas." Likewise, s02' N02 , and 

Pb nonattainment areas are subject to the applicable gener~1 

nonattainment "provisions in subpart 1 as well as the more 

specific requirements in subpart 5, "Additional Provisions for 

Areas Designated Nonattainme,Ht for Sulfur Oxides, "Nitrogen Dioxide, and Lead." . " 

i. Section 172 (c) Requirements· 

This section contains general requirements. for nonat:tainment 

plans. A thorough discussion of.these requirements may be found 

in the General Preamble to Title I [57 FR 13498 (April 16, 

1992)]. The EPA anticipates that areas will already have met 

most or all of these requirements to the extent that they are not 

superseded by more specific Part D requirements. The 

requirements for reasonable further progress, identification of 

certain emissions increases, and other measures needed for. 

attainment will not apply for redesignations because they only 

have meaning for areas not attaining the standard. The 

requirements for.an emission inventory will be" satisfied by the 

inventory requirements of the maintenance plan. The requirements 

of the Part D new source review program will be replaced by the 

prevention of significant deterioration (PSD) program once the 

area has been redesignated. However, in order to ensure that the 

PSD program will become fully.effective immediately upon 

redesignation, either the state must be delegated the Federal PSD 

program or the State must make any needed modifications ·to its 

rules to have the approved PSD program apply to the ·affected area 

upon r:edesignation. "d· 

ii. ". Conformity 

The state must work with EPA to show that· its SIP 

provisions are consistent with section 176(c)(4) conformity" 

requirements. The redesignation request should include 

conformity procedures, if the state already has these procedures 

in place: Additionally, we currently interpret the conformity" 

requirement to apply to attainment areas. However, EPA has not 

yet issued its conformity regulations specifying what areas are 

subject" to the conformity requirement. Therefore, if a state 

does not have conformity proc~dures in place at the time that it" 

submits a redesig~ation request, the state" must commit to follow 

EPA'!; conformity regulation upon issuance, as applicable. If the 

state sUbmits the "redesignationrequest" subsequent" to EP1\'s' " 

issuance of the conformity regulations, and the conformity 

requirement became applicable to the area prior to submis!;ion, . , ~ . 
7 

the state must adopt the applicable conformity requirements 

before EPA can redesignate the area. 

5. Maintenance Plans 

section 107(d)(3)(E) of 'the amended Act stipulates that for 

an area to be redesignated, EPA must fully approve a maintenance 

plan which meets the requirements of section 1'75A. A state ma~ 

submit both the redesignation request and the maintenance plan at 

the same time and rulemaking on both may proceed on a parallel, 

track. Maintenance plans may, of course, be submitted and 

approved by EPA before a redesignation is requested. However, 

according to section 175A(c), pending approval of the maintenance 

,plan and redesignation request, all ,applicable' nonattainment ar'ea 

requirements shall remain in place. ,I 

section 175A defines the general framework of a ,maintenance 

plan. The maintenance plan Wil,l constitute a SIP revisi,on arid I 

must provide for maintenance of the relevant NAAQS in the area ' 

for at least 10 years after redesignation. Section 175A further 

states that the plan shall contain such additional measures, ii 

any, as may be necessary to ensure such maintenance. Because the 

Act requires a demonstration of maintenance for 10 years after Ian 

area is redesignated (not 10 years after submittal of a 

redesignation request), the State should plan for some lead time 

for EPA action on the request. In other words, the maintenance 

demonstration should project maintenance for 10 years, beginning 

from a date which factors in the time necessary for EPA review] 

and approval action on the redesignation request. In determining 

the amount of lead time to allow, States should consider that I 

section 107(d)(3)(D) grants the Administrator up to 18 months 

from receipt of a complete ,submittal to process a redesignation 

request. The statute also requires the State to submit a I 

revision of the SIP 8 years after the original redesignation 

request is approved to provide for maintenance ,of the NAAQS fo~ 

an additional 10 years following the first 10-year period [see 

section 175A(b)]. 

In addition, the maintenance plan shall contain such 

contingency measures as the'Administrator deems necessary to 

ensure prompt correctiori of any violation of the NAAQS [see 

section 175A(d)]. The Act provides that, at a minimum, the 

contingency measures must include a requirement that the State 

will implement all measures contained in the nonattainment SIP 

prior to redesignation. Failure to maintain the NAAQS and 

triggering of the contingency plan will not necessitate a 

revision' of the SIP unless required by the Administrator, as 

stated in section 175A(d). 

The following is a list of core provisions that we 

anticipate will be necessary to ensure maintenance of the 

relevant NAAQS in an 'area seeking redesignation from 
8 

nonattainment to attainment.. We th~refore recommend that States 

seeking redesignation of a' nonattainment area consider these 

provisions. However. any final 'EPA determination regarding the 

adequacy of a maintenance plan will be made following review of 

the plan submittal in light of the particular 'circumstances 

facing the area proposed for redesignation and based on all 

relevant information available at the time. I . 

a .. , Attainment Inventory 

The State should develop an attainment emissions inventory 

to identify .the level of emissigns in the area which is , sufficient to attain the NMQS. . This inventory, 'should be '. 

'consisterit 'with EPA's most recent guidance on emission 

inventories for nonattainment areas available at the time and 

should include the emissions during the time period associated 

with the monitoring data showing attainment. 6 . , , 

Source size thresholds are 100 tons/year for SO , N02 • and 

PM-10 areas, and 5 tons/year for Pb based upon 40,CF~ 51.100(k) 

and 51.322, as well as established practice for AIRS data. The 

source size threshold for serious PM-IO areas is 70 ,tons/year 

5Where the State has made an adequate demonstration that air 

quality has improved as a result of the SIP (as discussed 

previously). the attainment inventory will generally be th~ 

actual inventory at the time the area attained the standard. 

6The EPA's current guidance on the prepar~tion of emission 

inventories for 03 and CO nonattainment.areas is contained in the 

following documents:. "Procedures for the Preparation of Emission 

Inventories for Carbon Monoxide and Precursors of Ozone: Volume 

I" (EPA-450/4-91':'016). "Procedures for the Prepara'tion of . Emission Inventories for Carbon Monoxide and Precursors of Ozone: 

Volume II" (EPA-450/4-91-014). "Emission Inventory Requirements 

for Ozone state Implementation Plans" (EPA-450/4-91-010), 

"Emission Inventory Requirements for Carbon Monoxide 

Implementation Plans" (EPA-450/4-91-011), "Guideline for 

Regulatory Application of the Urban Airshed Model" (EPA-450/4-91-

013). "Procedures for Emission Inventory Preparation: Volume IV, 

Mobile Sources" (EPA-450/4-81-026d). and "Procedures for 

Preparing 'Emission. Inventory Projections" (EPA-450/4-91-019). 

The EPA does not currently have specific guidance on attainment 

emissions inventories'for S02" In lieu thereof. States are 

referred to the guidance on emissions data to be used as input to 

modeling demonstrations. contained in Table 9.1 of EPA's 

"Guideline on Air Quality Models (Revised)" (EPA-450/2-78-027R). 

July 1987 .,J.,hJc;:h is. q~nerally applicable to, all, criteria .. ,', 

pollutants.Emission inventory procedures and requirements 

documents are currently being prepared by' OAQPS 'for PM-,10 and Pb; 

these documents are due for release by summer 19.92. 
· .... 

,#,~s 

9 

according to Clean Air' Act section l89(b)(3). HoweVer, the 

inventory should include sources below these size thresholds i 

these smaller sources were included in the SIP attainment 

demonstration. Where sources below the 100; 70, and 5 tons/ye rsize thresholds (e.g., areas with smaller source size 

definitions) are subject to a state's minor source permit 

program, these sources need only be addressed in the aggregate to 

the extent tha.t: they result in areawide growth. 

~. For 03 nonattainment areas, the invento)."y should be based on 

actual "typical summer day" emissions of'OJ precursors (volatile 

organic compounds and,nitrogen oxides) dur).ng the attainment· 

year. This will generally correspond to one of the periodic 

inventories required for nonattainment areas to reconcile 

milestones. FOr CO nonattainment areas, the inventory should be 

based on actual "typical Co season day" emissions for the 

attainment year. This will generally correspond to one of the 

periodic inventories required for nonattainment areas. 

b. Maintenance Demonstration 

A State may generally demonstrate maintenance of the NAAQS 

by either showing that future emissions of a pollutant or its I 

precursors will not exceed the level of the attainment inventory, 

or by modeling to show that the future mix of sources and 

emission rates will not cause a violation of the NAAQS. Under 

the Clean Air Act, many areas are required to submit nodeled 

attainment demonstrations to show that proposed'reductions in 

emissions will be sufficient to attain the applicable NAAQS. ~or 

these areas, the maintenance demonstration should be based upon 

the same level of modeling. In areas where no such modeling wa!s' 

required, the State should be able to rely on the attainment I 

inventory approach. In both instances, the demonstration shouldbe for'a period of 10 years following the redesignation. . c::: 

Where modeling is relied upon to demonstrate maintenance, 

each plan should contain a summary of the air quality 

concentrations expected to result from application of the control 

strategy. In the process, the plan should identify and descrii:Je 

the dispersion model or other air quality model used to projec~ 

ambient concentrations (see 40 CFR 51. 46) • . .0 I' 

In either case, to satisfy the demonstration requirement t~e state should project emissio. nsfor the lO-year period fOllowing

l 

redesignation, either for the purpose of showing that emissions 

will not ~ncrease over the attainment inventory or for conducting modeling. The projected inventory should consider future 

growth, including 'population and industry, should be consistent 

7Guidance for projecting emissions may be found in the 

emissions inventory guidance cited in footnote 6. 

.. )" ~, 
10 

with the attainment inventory, and 'should doCument data inputs and assumptions. All elements of the demonstration (e. g.', 

emission projections, new source growth, and m~deling) should be 

consistent with current EPA modeling guidance. For 03 and CO, 

the projected emissions should reflect the expected actual 

emissions based on enforce~ble emission rates and typical' 

production rat~s. 

For CO, a state should address the areawide component of the' 

maintenance demonstration either by showing that future CO' 

emissions will not increase or by conducting areawide modeling. 

Preferably, the State should carry out hot-spot ,modeling that is 

consistent with the Guideline on AirOuality Models (Revised), in 

order to demonstrate maintenance of the NAAQS. In particular, if 

the.nonattainment problem is related to a pattern of hot-spots 

then hot-spot modeling should generally be ,conducted. However, 

hot-spot modeling is not automatically required .. For example, if 

the nonattainment problem was related solely to stationary point 

sources, or if highway improvements have been implemented and the 

associated emission reductions ,and travel characteristics can be 

qualitatively documented, then hot-spot modeling is not required. 

In such cases, adequate documentation as well as the concurrence 

of Headquarters is needed. "'., 

Any assumptions concerning emission rates must reflect 

permanent, enforceable measures. In other words, a State 

generally cannot'take credit in the maintenance demonstration for 

reductions unless there are'regulations in place requiring those 

'reductions or the reductions are-otherwise.shown to be permanent. 

Therefore, the State will be expected to maintain its implemented 

control strategy despite redesignation to attainment, unless such 

measures are shown to be unnecessary for maintenance or a~e . replaced with measures that achieve equivalent reductions (see 

additional discussion under "contingency Plan"). Emission 

reductions from source shutdowns can be considered permanent and 

enforceable to the extent. that those shutdowns have been 

reflected in t~e SIP and all applicable permits have been 

modified accordingly. 

Modeling used to demonstrate attainm!!nt may be, relied upon 

in the maintenance demonstration where the modeling conforms to 

current EPA guidance and where the State has projected no 

significant changes in the.modeling inputs during the intervening 

time. Where the original attainment demonstration may no longer 

be relied upon, States will be expected to remodel using current 

8The EPA-approved modeling guidance may be found in the . fOllowing documents: "Guideline on Air Quality Models 

(Revised) ," OAQPS, RTP, NC (EPA-450/2-78-027R); July 1986; 'and 

"PM-I0 SIP Development Guideline," OAQPS, RTP, NC(EPA-450/2-86-

001), June 1987. 
11 

EPA referenced techniques. 9 This may be necessary where, for 

example, there has been a change in emissions or a change in t e 

siting of new sources or modifications' such that air quality m y 

no longer be accurately represented by the existing modeling. 

c. Monitoring Network 

Once an area has been redesignated, the State should 

continue to operate an appropriate air quality monitoring 

network., ln accordance with 40 CFR'Part 58, to verify the 

attainment status'of the area. The maintenance plan should 

contain provisions for continued operation of air quality monitors that will provide such verification. In cases where 

measured 'mobile source parameters (e.g., vehicle miles traveled 

congestion) have changed over time, the state may also need tol 

perform a saturation monitoring study to determine the need for, 

and location of, additional permanent monitors. 

d. Verification of Continued Attainment 

Each State should ensure that it has the legal authority to 

implement and enforce all measures necessary to attain and to I 

maintain the NAAQS •. Sections 110(a)(2)(B) and (F) of the Clean 

Air Act, as amended, and regulations promulgated at 40 CFR 

51.110(k), suggest that one such measure is the acquisition of 

ambient and source emission data to demonstrate attainment and 

maintenance. 

Regardless of whether the maintenance demonstration is based 

on a showing that future emission inventories will not exceed the 

attainment inventory or on modeling, the state submittal should 

indicate how the state will track the progress of the maintenance 

plan.- This is necessary due to the fact that the emission 

projections made for the maintenance demonstration depend on 

assumptions of point and area source growth. 

,- One option for tracking the progress of the maintenance 

demonstration, provided here as an example, would be for the 

State to periodically update the emissions inventory. In this 

case, the maintenance plan should specify the frequency of any 

planned inventory updates. such an update could be based, in 

part, 'on the annual AIRS update and could indicate new source 

growth and other changes from the attainment inventory (e.g., 

changes in vehicle miles travelled or in traffic patterns). As 

an alternative to a complete update of the inventory, the State! 

may choose to dO. a comprehensiv. e review of the factors that wez'le 

used in developing the attainment inventory to show no 

significant change. If this review does show a significant 

change, the State should then perform an update of the inventory. 

9see references for modeling guidance cited in footnote 8. 
12 

Where the demonstration is based on modeling, an option for 

tracking. 'progress would be for the State to periodically . (typically every 3 years) reevaluate the modeling assumptions and , input data. In any event, the state should monitor the 

indicators for triggering contingency measures (as discussed 

below) . 

e. contingency Plan 

section 175A of the,Act als6 requires that amaintenanc~ plan include contingency provisions, as necessary, to promptly 

correct any violation of the NAAQS ~hat occurs after 

redesignation of the area. These contingency measures are 

distinguished from those generally required for nonattainment 

areas under section 172(c)(9) and those specifically' required for 

o 'and CO nonattainment areas under sections 182(c)(9) and 1~7(a)(3), respectively. For the purposes of section 175A, a 

state is not required to have fully 'adopted contingency measures 

tha,t will take effect ,without further action by the state in 

order for the maintenance plan to be approved. However, the ,_ contingency plan is, considered to be an enforceable part of the 

'SIP·and should ensure that the contingency measures are 'adopted 

expediently once they are triggered. The plan should clearly 

identify the measures to be adopted, a schedule and procedure for 

adoption and implementation, and a specific time limit for action 

by the state. As a necessary part of the plan, the state should 

also identify specific indicators, or triggers, which will be 

used to determine when the contingency measures need to be 

implemented. 

Where the maintenance demonstration is based 6n the 

inventory, ,the State may, for example, identify an "action level" 

of emissions as the indicator. If later inventory updates show 

that the inventory has exceeded the action level, the State would 

take the necessary steps to implement the contingency measures., 

The indicators would allow a State to take early action to 

address potential violations of the NAAQS before they occur. By 

taking early action, States may be able to prevent any actual 

violations of the NAAQS and, therefore, eliminate the need on the 

part of EPA to redesignate an area to nonattainment • 

. Other indicators to consider include monitored or modeled' 

violations of the NAAQS (due to the inadequacy of monitoring data 

in some situations). It is important to note that air quality data in excess of the NAAQS will not automatically necessitate a 

revision of the SIP ,where implementation of contingency measures 

is adequate to address the cause of the violation. The need for 

a SIP revision is subject to the Administrator's discretion. , , 

The EPA will review what constitutes a contingency plan on a 

case-by-case basis. At a minimum, it must require that the State 

will implement all measures contained in the Part D nonattainment 
13 

plan for the area prior to redesignation [see section l75A(d)]. 

This language suggests that a State may submit a SIP revision kt 

the time of its redesignation request to remove or reduce the I 

stringency of control measures. Such a revision can be approved 

by EPA if it provides for .compensating equivalent reductions. I A 

demonstration that measurEls are equivalent would have. to include 

appropriate modeling or an adequate justification. Altern~­

tively, a state might be able to demonstrate (through 

EPA-approved modeling) that the measures are not necessary for 

maintenance of the standard. In either case, the contingency 

plan would have to provide for implementation of any measures 

that were reduced or removed after redesignation of the area. 

Summary 

As stated previously, this memorandum consolidates EPA's 

redesignation and maintenance plan guidance and Regions should 

rely upon it as a general framework in drafting Federal Regist'er 

notices. It is strongly suggested that the Regional Offices I 

share this document with the appropriate States. This should 

give the States a better understanding of .what is expected from a 

redesignation request and maintenance plan under existing poli'cy. 

Any necessary changes to existing Agency policy will be made 

through our action on specific redesignation requests and the 

review of section 175A maintenance plans for these particular 

areas, both of which are subject to notice and comment rulemaking . procedures. Thus, in applying this memorandum to specific I 

circumstances in a rulemaking, Regions should consider the 

applicability of the underlying policies to the particular 'facts , . , and to comments subm~tted by any person. If your staff membe~ls 

have questions which require clarification, they may contact 

Sharon Reinders at (919) 541-5284 for 0 3- and CO~related issues, 

and Eric Ginsburg at (919) 541-0877 for S02-' PM-10-, and 

Pb-related issues. 

cc: Chief, Air Branch, Regions I-X 

John Cabaniss, OMS 

Denise Devoe, OAQPS 

Bill Laxton, TSD 

Rich Ossias, OGC 

John Rasnic, SSCD 

John Seitz, OAQPS 

Mike Shapiro, OAR 

Lydia Wegman, OAQPS 
Page Intentionally Left Blank
Appendix B

Redesignation of Sulfur Dioxide Nonattainment Areas in the Absence of 

Monitored Data, Memorandum, John Seitz, Director, 

Office of Air Quality Planning and Standards, 

U.S. Environmental Protection Agency, October 18, 2000
Page Intentionally Left Blank
-. ~ -~~-~ . ,"Il, . '. " 

. / ' 

, J' /. 1 

I . ' . 

RECE1'VEO' 

.'. OCT 26 2Doo . . . . 

uNITED STATES· ENVIRONMENTAL PROnCTION AGENCY 

RESEARCH TRIANGLE PARK. NC 2771 1 

AIR DIVISION '. 

U.S; EPA, REGION'9 

OCT, 1 8 ,- "':-

I\tIEMORANDUM ' 

. OFFICE Of 

AIR. QUAUTY PlANNING 

AND STANDARCS . 

SUBJECT: Redesigna#on of S~ Dioxide Nonatt:ljnm~' Areas in th~ Absence of 

Monitored, Data 

John S. Seltz, Directo 

Office.of Air Quality PI 

TO: Regional Office Air Division Directors 

-1"0) 

. . 

The purpose of this memorandmn is to proVide guidance .on redesignating·.sulfW dioxide 

(S02) nona~ent areas to a~ent, in cases where th~ areas' historic violations were 

caused by inajor point-sources .of sulfur oxide (SOx) ~ssio;ns that are no lopger in operation. 

States in some cases have~ with out approval, removed S02 momtQrs from these areaS 

immediately following the shutdown of the SOx emissl<;>Os sources .. In these tases,states face 

the'prospect of continued nonattirinment designations' for areas where there is no reas«::>nable basis 

for as~g that S02 violations persist. 

. I.. 

. . This,guidance provides an approach for redesigruiting these m:~as to attaiDment in the 

. absence of monitoring data and for exempting 1'h:ese are.3$ froin 'the mainten~ce plan . . 

. requirements for coDrlnued monitoring within the areas. In addition, this policy deScnces' how 

a~ent and continued mruntenance should be demonstrated and how SOUl'ces currently shirt . 

" doWn shouJd be treated if they resume·operation~. TJl,erefore, this policy amends:portions of . 

previous redesignation policies, including '"Procec.:lures for ~ce~sing Requ~ts to Redesignate . 

. . .Areas to Attamment, " memo from John Calcagni, AQMD Director,. dated' 9/4/92;' "Section "1'07 . 

. .Desigpation Policy SUmmary," m~o from Sheldon Meyers, dAQPSDirectO~, dated 4121183, 

pe$ining to ambient air qualitY data shOwlDg aitai.nri:Ient aDd maintenance of the S02 National 

. Ambient Air Quality Standar~s (NMQS); and· ~ Attainment Deiermin~tk)li Pelley for S~. 

Dioxide NonattainInent Areas;'~ memo ·ftpm Sally 1. Shaver, AQSSD Director, dated 1/26/95., 

All'other pro:visions of the previous redesignation policies still apply, inc1ti~g provisrons 

relating to contingency me~s.· " .'. ,..' .:. 

" 

" ~., 

-" .. ' 
• 

II· . 

II 

II .' 

1

(\,', 

'J 

II 

II 

I 

I 

I 

I 

It. 

I 

I 

-

1\ 

I, 

W· 

. 2 

. The Environmental Protection Agency's (EPA) 'historic redisigIfation policy for S02 has 

called-for 8 quarters ofclean ambient air· quality data for rede.signatio~ to attainment. Although . 

EPA has allowed as few as 4 quarters of ambient data if an acceptable modeling analysis haS 

been perfonned. I Areas that lack S02 monitors cannot meet. even the requirement for 4' quarters . 

of clean' data' However, EPA believes that it is not a reasonable use ofliIDited monitoring 

resources to reesmblishmonitors in ord.er to collect at least.4 quarters of data.in areas where 

violations of the S02 NAAQS were caused by sources that no 10n~er operate. 

pespite the absence of clean air quality data, EPA believes ·that it may approve a State's 

request to redesignate such 802 nonattainment areas to att8.inment providect that th~ State 

submits a maintenance plan that addresses certain criteria. . 

First, the plan should include 3 emissions inventories: 

(a) An inventory representing actual emissions during the period 'when there were . 

violations of the S02 NAAQ8; 

. . . (b) An inventory representing current actual and allowable emissions (or potential 

emissions, if there is no allowable emissions level); and 

(c) An inventory projecting allowable emissions (or potential emissions, if there is no 

allowable emissions leyel) to the 10th year after redesignation. 

The inventories should display emisslons from each poult source of SOx, with explanations of 

significant emissions changes, includmg source shutdoWns.2 The inventories should include SOx 

emissions from all SOx point sources in; and within a 50 kilbmeter range of, the nonattainmeilt 

area boundary .. Again, if there is no allowable emissions level, potential emissions should be ~~. . . . 

Second, the maintenance plan should fuclud~ ~ dispersion'modelinganaIysis: of all-S0~' . 

point sources in, ~d within 50 kilometers of, the nona~ent area bound,an~s USing the 

emissions inventories described above and the techi;riques and data prescribed in 40,CI:R 51 

Appendix W. The modeling .analysis· Should show that: . 

ISee the Meyers memQ referenced above. -Both the Meyers and Calcagni memos 

recognize that for S02 nonattamment areas monitoring data alone may not be sufficient for 

redesignating areas to attainment; dispersion modeling may be needed. 

2The inventories should include other sources if they were included in the attainment 

demonstration.' ... 
, ............... -....... -.-..... -.......... -~ ..... ': 

3 

. (a) No S02 NAAQS violations pres~nt1y occur cir c~:.·be projected·to occur chir:ing 

the next 10 years anywb~e Within the nonattaimnent area;; and, - . . ! •.•• • .... 

(b) Point sources, which have since shut do~ were the dominant sources 

contributing tc? high S02 concentrations in the airshed. 

Third, the mamteoance .plan should include evid~ce that if the SO~ point source that 

caused the S02 NAAQS Violations in the past resumes operation1 itwould be 'considered a , 

"new'~ source.' Thus the maintenance plan should show that iftbis ''D.ew'· $Ox source woqld be a 

major source~ it should obtain a pe~t conforining to applicable:requjrements. 6fthe Prevention 

of Significant Deterioration program b~fore resuming operations; or if it would not be a major ' 

source, it should obtain a Imnor source permit under .the ,State' s 8IP-approv~d minor source 

p~rmitting rules in effect at the time it"obtains a. permi4: before it may reSUI:Jle operation. The 

·maintenance plan should'provide that before such a permit is issued, the dispersion model should 

be re-run., using the same meteorological data base, to determine whetherre-Starting' the source 

would'interfere withmaintemince, and should provide that the permit will not be issued if the 

model indicates that re-starting the source would interfere with. maintenance., . 

A' Fourth, the maintenance plan should include commitments to.reSU!¥e ambient monitoring 

before any major source .of SOx: emissions commences operation. ·'~1 . ~.... .~~ ... . ...ft . . •• ~ •• ;. d'· .:' • ~ •• :~ ,. 

, . , . , ,'Tiris policy applies. only,to S02 nona-rtahnnent areas because violations in such areas are 

~erally dominated by rel~tive1y few point sources (such as cOpper smelt~rs or power plants) 

arid have insi gnificant. area and mobile source emission contributions. As: h result, there is a 

direct association between the point sources' emissions' and ambient 802 c-{)ncentIations. 

DisperSion modeling will assure that 802 NAAQS violations are no longer occurring and wolild 

not be expected to recur in the future. . ......... ~ .. :; 

," This gUidance memo~dum does not hnpose binding~ enforceable :,~quirements on any 

party, arid may not apply,to a particular situation based upon: the circumstances. The EPA r¢tains . ·1' 

.,:th,~. qiscretion to adopt'approaches to addressing maintenance plan provisionS that differ from this 

,.'- guidance where appropriate., Any final decisions by EPA regarding:a'pamcular S02 ' 

r maintenance plan will only, be made, in the context of a rulemalcing, action regarcting that 

~ainten3nce plan based upon the applicable statUtory and regulatory provisions, which do 

c~n~ legally·binding requirements. Therefore, interested parties, including States, are free to 

.' 'nuse questions and objections' about the appropriateness of this guidance or the application of 

tl:i:is guid3nce to a particular situation; EP A will consider. whether or not the recommendations in 

the guidance are appropnate in that situation. The EPA welcomes public ·comments on $is . 

document at any time and will consi4er those comments in any future revisiQD of this guidance 

do.cUment, which may occur withoUt public notice. 

., 

'o' 
4 

I urge Regions to coordinatec1os¢ly with OAQPS' Air Quality Standards and Strategies 

. Division in deterniining.whether S02 redesignation requests may be subject to this policy and to 

ensure.that States' submissIons adequately-address this and the·preVious polici~s' criteria for 

redesignating 802 nomittaimnent are~ to attainment - . 

cc: Lydia Wegman, AQSSD 

David Mobley, EMAD 

, Joe Paisie~ IPSG 

Rich Ossias, OGe. 

....... : •... ;.;,:.: •.•.••.••.• I 

',~~.:. ::~~.i{~·:~ \~~~~~\\ 

·"{~i~:t '\: 
502 Redesignation Poli~y M·emo 

Policy Purpose: To amend existing. requirements for 

redesignating 80~ NAAs to attainm(3nt, in 

order to allow for redesignations· .where: 

(1) past violations were due to emissions 

from a single source; . 

(2) the single sour.ce has shut down; 

(3) all monitors have been removed. 

Policy Approach: . Maintenance plan must i[lclude: 

Policy Application: 

.. . Policy Benefits: 

(1) . emissions inventories representing 

(a) actual emissions when violations 

occurred; (b) current emissions; and (c) 

emissions projected to the· 1 Oth year after 

.redesignation). 

(2) dispersio~~ modeling showing (a) no 

NAAQ8 violations occur or can be 

projected for ·the next.. 10 years; and (b) 

the shutdown sources were the 90rninant 

cause of high conc~ntratjons in the past. 

(3) evidence that if the shutdown sources 

resume· operation ·they will be considered 

new sources and required to obtain a 

PSD permit 

(4) commjtment~ to resume mbnitorin·g 

before any major SOx source . 

commences operation. 

Restr.icted to .$02 NAAs· because 802 

violations are frequently caused by a .few 

point sources 

Allows redesignationof $everal 802 

. NAAs t6 attainment, without requiring 

collection of ambient data 
Page Intentionally Left Blank
Appendix C

SO2 Emissions Inventories for 2011 and Subsequent Years through 2030,

Arizona Department of Environmental Quality, June 20, 2014
Page Intentionally Left Blank
SO2 Emissions 

Inventories for 2011 

and Subsequent Years 

through 2030 

Technical Support Document 

for the Morenci SO2 

Maintenance Plan

Arizona Department of 

Environmental Quality

June 20, 2014
Table of Contents

1. EMISSIONS INVENTORY & METHODOLOGY....................................................................1

1.1 Emission Inventory for the SO2 24-hour and Annual Standard...............................................................................1

1.2 2011 Baseline Emissions Inventory – Methodology ...............................................................................................1

1.2.1 Population and Area Based Emission Allocation Methodology ...........................................................................1

1.2.2 Non-Road Mobile Activities..................................................................................................................................3

1.2.3 On-Road Mobile Activities....................................................................................................................................4

1.2.4 Area (non-point) Activities....................................................................................................................................4

1.2.5 Industrial (point) Sources.....................................................................................................................................6

Figure 1: Morenci SO2 Maintenance Area with 50 Kilometer Buffer ........................................................................10

2. MORENCI SO2 MAINTENANCE AREA EMISSIONS INVENTORY FOR POINT, AREA 

AND MOBILE SOURCES FOR THE BASE YEAR 2011..........................................................11

3. PROJECTED SO2 EMISSIONS INVENTORY FOR POINT, AREA AND MOBILE 

SOURCES THROUGH 2030........................................................................................................11

3.1 Summary of Emissions Projections for 2011 – 2030.............................................................................................13

4. REFERENCES ..........................................................................................................................15

LIST OF TABLES

TABLE 1: ADOA 2011 POPULATION OF MORENCI CDP, CLIFTON, AND GREENLEE CO. .........................2

TABLE 2: NON-ROAD MOBILE SO2 EMISSIONS FOR GREENLEE COUNTY AND THE MORENCI SO2

MAINTENANCE AREA.....................................................................................................................................3

TABLE 3: ON-ROAD MOBILE SO2 EMISSIONS FOR GREENLEE COUNTY AND THE MORENCI 

MAINTENANCE AREA.....................................................................................................................................4

TABLE 4: AREA (NON-POINT) SO2 EMISSIONS FOR GREENLEE COUNTY AND THE MORENCI AREA..6

TABLE 5: SO2 POINT SOURCES WITHIN MORENCI SO2 MAINTENANCE AREA ..........................................8

TABLE 6: SO2 POINT SOURCES WITHIN 50-KM BUFFER, OUTSIDE MORENCI SO2 MAINTENANCE 

AREA...................................................................................................................................................................9

TABLE 7: MORENCI SO2 MAINTENANCE AREA – 2011 BASELINE EMISSION ESTIMATES....................11

TABLE 8: MORENCI SO2 MAINTENANCE AREA 2011 – 2030 POPULATION PROJECTION........................12

TABLE 9: MORENCI SO2 MAINTENANCE AREA 2011 – 2030 PROJECTED EMISSION ESTIMATES ........14

LIST OF FIGURES

FIGURE 1: MORENCI SO2 MAINTENANCE AREA WITH 50 KILOMETER BUFFER.....................................10
1

1. EMISSIONS INVENTORY & METHODOLOGY

1.1 Emission Inventory for the SO2 24-hour and Annual Standard

The following sections in this Technical Support Document (TSD) provide a discussion of the 

methodologies used to develop the 2011 baseline emissions inventory and future year inventories 

for the Morenci maintenance area from identified contributing source categories and a 

presentation of the derived inventories. This TSD was developed to help demonstrate continued 

maintenance of the 1971 24-hour and annual SO2 NAAQS for the Morenci SO2 planning area.

1.2 2011 Baseline Emissions Inventory – Methodology

The source categories used in the emissions inventory are a standardized list of sources which 

has been followed in previous State Implementation Plans (SIPs). These categories include: 

 Non-road Mobile (exhaust) sources 

 On-road Mobile (exhaust) sources

 Industrial (point) sources

 Area (non-point) sources

Area and Mobile emission data were updated using 2011 National Emission Inventory (NEI)

Version 1 data. Since ADEQ permits industrial point sources, ADEQs datasets were used 

because they were the most accurate and recent SO2 emissions data for facilities located within 

the maintenance area and the surrounding 50 km buffer area.

1.2.1 Population and Area Based Emission Allocation Methodology

ADEQ implemented a top down methodology by utilizing the 2011 NEI Version 1 inventory for 

Greenlee County. For source categories whose emissions may be significantly associated with 

the general population, the county-wide emissions reported in the 2011 NEI Version 1, the most 

recent EPA certified emissions data available, were adjusted to the Morenci Maintenance Area 

using the population ratio of the Town of Clifton and the Morenci CDP to that of Greenlee

County as a metric for scaling county level emissions to the Morenci Maintenance Area

1

.

Population adjustments:

2011 Morenci Maintenance Area Pop. = 2011 Clifton Pop. + 2011 Morenci CDP Pop. = 4,755

 

1 The designation “Morenci Maintenance Area” refers to the combined population of the Towns of Morenci and 

Clifton and the designation “Morenci CDP” refers to the population of the Town of Morenci, AZ.
2

2011 Greenlee County Pop. = 8,380

Therefore, the Population Adjustment Ratio = 2011 Morenci Maintenance Area Population / 

2011 Greenlee County Population, or:

4,755 / 8,380 = 0.5674 (56.74%)

Population Adjustment Ratio = 56.74 %

Table 1: ADOA 2011 Population of Morenci CDP, Clifton, and Greenlee Co.

Location 2011

Morenci CDP 1,482

Clifton 3,273

Morenci Maintenance Area 4,755

Greenlee County 8,380

Source: Arizona Department of Administration (ADOA) http://www.workforce.az.gov/population-projections.aspx

Area adjustments:

Source emissions not adjusted from the County level to the Morenci SO2 Maintenance Area 

based on the population adjustment ratio calculated above were adjusted based on the Area 

Adjustment Ratio of 13.31 % calculated below: 

Greenlee County Area = 4787.4 km2

Morenci Maintenance Area = 637.3 km2

Area Adjustment Ratio = Morenci SO2 Maintenance Area / Greenlee Co Area 

Area Adjustment Ratio = 637.3 km2/ 4787.4 km2= 13.31%

Railway adjustment

Since some of the railways in Greenlee County were outside the maintenance plan boundaries 

and the remainder railways were inside the SO2 maintenance area, it was important to 

appropriately adjust the Greenlee County non-road, locomotive mobile source emissions to the 

Morenci SO2 Maintenance Area. Google Earth was used to measure the length of railway both 

outside and inside the maintenance area. The railway length ratio was found to be approximately 

20 % and the calculations are shown below.

Greenlee County railway length = 40 miles

Morenci Maintenance area railway length = 8 miles
3

Railway length Adjustment Ratio = Morenci SO2 Maintenance Area / Greenlee Co Area 

Railway length Adjustment Ratio 8 miles / 40 miles = 20%

1.2.2 Non-Road Mobile Activities

For the Non-Road Mobile Activities category, ADEQ employed a top down methodology using

the 2011 NEI Version 1 inventory for Greenlee County. The county-wide emissions reported in 

the 2011 NEI Version 1 were adjusted to the Morenci Maintenance Area using either the 

population adjustment ratio, the area adjustment ratio, or the railway length adjustment ratio of 

the Morenci Maintenance Area to that of Greenlee County.

Non-Road Mobile Emissions Calculations

The NEI reported a total of 0.33 tons of SO2 emissions from non-road mobile source activities in 

Greenlee County (see Table 2) for the year of 2011. Based on the population adjustment ratio of 

56.74 % and the railway track ratio of about 20 %, SO2 emissions from non-road mobile sources 

in the Morenci SO2 Maintenance Area were estimated to be 0.08 tons for 2011.

Table 2: Non-Road Mobile SO2 Emissions for Greenlee County and the Morenci SO2

Maintenance Area

Source Description Tons/yr

(Greenlee Co.)

Adjustment 

Ratio

*Tons/yr 

(Morenci 

Maintenance 

Area)

Mobile Locomotives 0.26 20.00% 0.05

Mobile Non-Road Equipment - Diesel 0.03 56.74 % 0.02

Mobile Non-Road Equipment - Gasoline 0.02 56.74 % 0.01

Mobile Non-Road Equipment - Other 0.00 56.74 % 0.00

Total 0.31 0.08

Data downloaded on 2-24-2014 from EPA 2011 National Emission Inventory Version 1 (NEI, 2011)

*Tons per Year (TPY) for the Morenci Maintenance Area were calculated by multiplying TPY (Greenlee Co.) by the Population 

Adjustment Ratio of 56.74 % or the Area Adjustment Ratio of 13.31%.
4

1.2.3 On-Road Mobile Activities

On-road mobile source activities were calculated by ADEQ by again using a top-down 

methodology, implementing the 2011 NEI Version 1 inventory for Greenlee County. The 

county-wide emissions reported in the 2011 NEI Version 1 represent the most recent EPA 

certified emissions data available. These values were estimated for the Morenci Maintenance

Area using the population adjustment ratio of the Morenci CDP and Clifton to that of Greenlee

County (56.74%) as a scaling metric for estimating Morenci Maintenance Area SO2 emissions 

from county level values.

On-Road Mobile Emissions Calculations

The 2011 NEI Version 1 reported a total of 0.58 tons of SO2 emissions from on-road mobile 

vehicle activities in Greenlee County during 2011 (Table 3). Based on the population adjustment

ratio, SO2 emissions from on-road mobile sources in the Morenci SO2 Maintenance Area were 

estimated to be 0.33 tons for the year of 2011 (56.74 % of 0.58 tons).

Table 3: On-Road Mobile SO2 Emissions for Greenlee County and the Morenci 

Maintenance Area

Source Description Tons/yr.

(Greenlee County)

Adjustment 

Ratio

*Tons/yr

(Morenci 

Maintenance 

Area)

Mobile On-Road Diesel 

Heavy Duty Vehicles 0.07 56.74 % 0.04

Mobile On-Road Diesel 

Light Duty Vehicles 0.00 56.74 % 0.00

Mobile On-Road Gasoline 

Heavy Duty Vehicles 0.03 56.74 % 0.02

Mobile On-Road Gasoline 

Light Duty Vehicles 0.48 56.74 % 0.27

Total 0.58 0.33

 Data downloaded on 2-24-2014 from EPA 2011 National Emission Inventory Version 1(NEI, 2011)

 *Tons per Year (TPY) for the Morenci Maintenance Area were calculated by multiplying TPY (Greenlee Co.) by the 

Population Adjustment Ratio of 56.74%.

1.2.4 Area (non-point) Activities

For Area (non-point) Activities sources, ADEQ again used the top-down methodology for 

calculation of Morenci Maintenance Area SO2 emissions based on the 2011 NEI Version 1 for 

Greenlee County. The county-wide emissions reported in the 2011 NEI Version 1 represent the 

most recent EPA certified emissions data available for fuel combustion source types. These 

values were estimated for the Morenci Maintenance Area using the population adjustment ratio 
5

of the Morenci Maintenance Area to that of Greenlee County (56.74%) as a scaling metric for 

estimating Morenci Maintenance Area SO2 emissions from county level values, as shown in 

section 1.2.1. 2011 Greenlee County SO2 emissions for agricultural field burning, wildfires and 

prescribed fires are also listed below. These values were estimated for the Morenci Maintenance

Area by use of the area adjustment ratio of 13.31%.

Area (non-point) Emissions Calculations

NEI and ADEQ reported a total of 3,949.93 tons of SO2 emitted from Area (non-point) source 

activities in Greenlee County during the year of 2011 (Table 4). While mining activities are

included as Area (non-point) SO2 sources in the 2011 NEI Version 1, ADEQ excluded the 

Freeport-McMoran Morenci, Inc. mining source activities from Area (non-point) source 

activities as to eliminate redundancy in this emission report since these emissions are included in 

Industrial (point) source activities (Section 1.2.5.). Based on the population adjustment ratio of 

56.74% and the area adjustment ratio of 13.31%, SO2 emissions from Area (non-point) sources 

in the Morenci SO2 Maintenance Area were estimated to be 525.94 tons for the year of 2011.
6

Table 4: Area (non-point) SO2 Emissions for Greenlee County and the Morenci Area

Source Description Tons/yr.

(Greenlee Co.) Adjustment Ratio

*Tons/yr.

(Morenci

Maintenance 

Area)

Fires Agricultural Field Burning 0.11 13.31% 0.015

Fires Prescribed Fires 20.38 13.31% 2.71

Fires Wildfires 3,928.97 13.31% 522.95

Fuel 

Combustion

Comm/Institutional –

Biomass 0.01 56.74 % 0.00

Fuel 

Combustion Comm/Institutional - Oil 0.01 56.74 % 0.01

Fuel 

Combustion

Electric Generation - Natural 

Gas 0.00 56.74 % 0.00

Fuel 

Combustion Electric Generation - Other 0.00 56.74 % 0.00

Fuel 

Combustion

Industrial Boilers, ICEs -

Natural Gas 0.00 56.74 % 0.00

Fuel 

Combustion Residential - Natural Gas 0.03 56.74 % 0.02

Fuel 

Combustion Residential - Oil 0.01 56.74 % 0.00

Fuel 

Combustion Residential - Other 0.00 56.74 % 0.00

Fuel 

Combustion Residential - Wood 0.20 56.74 % 0.11

Industrial 

Processes

Industrial Processes - Oil & 

Gas Production 0.00 56.74 % 0.00

Miscellaneous Non-Industrial NEC 0.00 56.74 % 0.00

Waste Disposal 0.21 56.74 % 0.12

Total 3949.93 525.94

Source: 2011 National Emission Inventory Version 1 (NEI) (Data was downloaded on 2-24-2014).

1.2.5 Industrial (point) Sources

When building an Emission Inventory (EI) of point sources within the Morenci Maintenance

Area, a large discrepancy was found to have occurred in emissions from the Freeport-McMoran 

Morenci, Inc. Copper Mine (previously permitted as the ‘Phelps Dodge Morenci Mine’

(PDMM)) between the years of 1990-1999 and 2000-2010. Prior to the year 2000, emissions 

from the facility rarely exceeded 1 ton/yr. From 2000-2010 the facility never emitted less than 

25 tons/yr. Review of historical ADEQ EI’s for the facility revealed fugitive emissions from 

blasting were not reported until the year of 2000 and thus were not included in the 2002 

‘MORENCI SULFUR DIOXIDE NONATTAINMENT AREA STATE IMPLEMENTATION 

AND MAINTENANCE PLAN’ EI or modeling efforts. Due to this discrepancy, the Morenci 

Maintenance Area EI and modeling efforts were updated to include these emissions in the 

currently submitted EI and modeling summary report.
7

Within the Morenci Maintenance Area, two SO2 emission facilities were identified: 1) FreeportMcMoran Morenci (FMMM), Inc. and 2) Morenci Townsite Wastewater Treatment Plant 

(WWTP) Emergency Generators (Table 5). 

Freeport-McMoran Morenci, Inc. 

The FMMM open-pit copper mine, ore processing and copper extraction facilities, located at 

33.0700 latitude and -109.3433 longitude, has been in existence since the early 1970s. It was 

originally permitted by the Arizona Department of Health Services (ADHS) and later by ADEQ. 

FMMM produces copper through conventional milling and froth flotation. ADEQ considers 

FMMM a major source for NOx and particulates. Due to the closing of the Copper smelter in 

1985, ADEQ no longer considers FMMM a major source for SO2 with the facility having a 

current potential to emit (PTE) of 87.6tons/yr. Recent FMMM emissions inventory data for SO2

indicate emission levels ranging from 25.0 tons/yr. to 56.0 tons/yr.

Current operating equipment with potential SO2 emissions at the source includes: 2 SO2 tanks, 2 

industrial boilers working in parallel with 2 gas turbines, 5 small industrial boilers, and one 

natural gas boiler. The total permitted allowable annual SO2 emissions from this process 

equipment is 1.61 tons. In contrast, the facility blasts rock during its regular mining efforts. 

This blasting has a PTE of 86.75 tons/yr. accounting for a potential of upwards of 98% of the 

annual FMMM SO2 emissions originating from this process.

Morenci Townsite WWTP Emergency Generators

The Morenci Townsite WWTP Emergency Generators permit allows for the emergency 

generation of power to the Morenci copper mine waste water treatment plant through the 

operation of four diesel generators. These generators range in size between 72.4 and 181 hp. As 

these generators are only permitted for use during emergency, maintenance, and testing periods, 

emissions are minimal (Table 5). This facility accounted for less than 0.01% of total SO2

emissions from all industrial (point) sources within the Morenci SO2 Maintenance Area.

50 Kilometer buffer surrounding the Morenci SO2 Maintenance Area

SO2 point source data were assembled for a 50-km buffer area around the Morenci SO2 

Maintenance Area. This area includes portions of Greenlee and Graham counties in Arizona and 

Catron, Grant, and Hidalgo counties in New Mexico. Sources in the two Arizona counties were 

determined by the ADEQ permitted facility list. It was confirmed, by the New Mexico 

Environment Department (NMED), that there were no New Mexico point sources within the 50 

km buffer.

There were 15 identified point sources in 2011 in the 50-km buffer region (Figure 1). Two of the 

point sources are within the Morenci SO2 Maintenance Area and the remaining 13 are within the 

50-km Buffer, but outside the Morenci SO2 Maintenance Area. Actual emissions and potential to 

emit (PTE) totals are shown in Tables 5 and 6 in tons per year (tpy). 
8

Table 5 shows that the actual emissions for point sources within the Morenci SO2 Maintenance 

Area (i.e. Freeport-McMoran Morenci’s Copper Mine and the Morenci Townsite WWTP 

Emergency Generators) emit well below the PTE limits listed for these sources. Those facilities 

located within the 50 km buffer show similar emission patterns where actual emissions only total 

38.05 tons for the year of 2011, while the PTE for this year was 167.38 tons. In order to be 

conservative, the PTE was used in the emission estimations for future years. Table 5 presents 

emission sources found within the Morenci SO2 Maintenance Area, while Table 6 presents those 

sources located within the SO2 50 km buffer region but not within the Morenci SO2 Maintenance 

Area.

Table 5: SO2 Point Sources within Morenci SO2 Maintenance Area

ID Source Latitude Longitude 2011

(tons/day)

2011

(tons/yr.)

PTE 

(tons/yr.)

Permit 

Status as 

of 2014

1

FreeportMcMoran 

Morenci, Inc.

33.0700 -109.3433 0.133 48.529 87.60 Active

2

Morenci 

Townsite 

WWTP 

Emergency 

Generators

33.0650 -109.3422 0.000 0.003 4.90 Terminated

Total 

Emissions 0.133 48.532 92.50

 Data Source: Arizona Department of Environmental Quality (ADEQ) and the 2011 NEI Version 1. Data 

verified by ADEQ Permits Section.
9

Table 6: SO2 Point Sources within 50-km Buffer, outside Morenci SO2 Maintenance Area

ID Source Latitude Longitude

2011

Actual 

Emissions 

(tons/day)

2011

Actual 

Emissions 

(tons/yr.)

PTE 

(tons/yr.)

Permit 

Status as 

of 2014

3

Arizona State Prisons -

Safford Complex 

(2010)

32.8289 -109.565 0.001 0.193 4.96 Terminated

4

City of Safford –

Water Reclamation 

Plant

32.8424 -109.7241 0.001 0.214 24.26 Terminated

5

CKC Construction 

Company (2012) 32.8563 -109.6878 0.000 0.126 11.60 Active

6

Freeport McMoran -

Central Analytical 

Service Center

32.8165 -109.6482 0.000 0.002 0.39 Active

7

Freeport McMoran 

Corporation - Bee 

Canyon Well Field

33.3167 -109.4667 0.003 1.044 8.24 Active

8

Freeport McMoran 

Corporation - Mud 

Springs Well Field

33.3833 -109.4833 0.003 1.087 5.62 Active

9

Freeport-McMoran 

Safford Inc. 32.9473 -109.6509 0.096 35 81.20 Active

10 Glenbar Gin, Inc. 32.9839 -109.8567 0.000 0.012 0.02 Active

11 Level 3 

Communications 32.8351 -109.7081 N/A N/A 0.21 Terminated

12 Mt. Graham Regional 

Medical Center, Inc. 32.8228 -109.7352 0.000 0.09 2.80 Terminated

13 Select Cleaners (2010) 32.8327 -109.7161 0.000 0.001 0.16 Terminated

14 Tri County Materials -

Hot Mix Asphalt Plant 32.8021 -109.7077 0.000 0.155 8.61 Active

15 USDOJ FCI - Safford 32.7667 -109.7167 0.000 0.122 24.27 Terminated

Total Emissions 0.104 38.05 167.38

Data Source: Arizona Department of Environmental Quality (ADEQ) and the 2011 NEI Version 1. Data 

verified by ADEQ Permits Section.
10

Figure 1: Morenci SO2 Maintenance Area with 50 Kilometer Buffer
11

2. MORENCI SO2 MAINTENANCE AREA EMISSIONS 

INVENTORY FOR POINT, AREA AND MOBILE SOURCES FOR 

THE BASE YEAR 2011

Summary of Estimated Emissions

Table 7 provides a summary of both annual and daily emissions estimates for the Morenci SO2

Maintenance Area calculated from the previously identified source categories and each source 

categories’ relative contribution to total SO2 emissions. 

Table 7: Morenci SO2 Maintenance Area – 2011 Baseline Emission Estimates

 Source Category

SO2 Emissions

(tons per year)

Morenci 

Maintenance 

Area SO2

Emissions*(tons 

per day)

Percent of 

total SO2

Emissions in 

Morenci

Maintenance 

Area

Greenlee

County

Morenci

Maintenance

Area

On-Road Vehicle 

Sources 0.58 0.33 0.00090 0.06%

Non-Road Vehicle 

Sources 0.31 0.08 0.00022 0.01%

Industrial (point) 

Sources** N/A 48.54 0.13296 8.44%

Area (non-point) 

Sources 3,949.93 525.94 1.44094 91.49%

Total N/A 574.89 1.57502 100.00%

* Tons per Year/365

** The point sources were located within the Morenci SO2 Maintenance Area.

3. PROJECTED SO2 EMISSIONS INVENTORY FOR POINT, 

AREA AND MOBILE SOURCES THROUGH 2030

Projecting future SO2 emissions requires taking into account economic growth, emissions control 

measures, capital turnover, fuel switching, technological change, and other activities of impact

making accurate projections of SO2 emissions difficult to forecast. Therefore, conservative 

forecasting of SO2 emissions is necessary to ensure future compliance with National Ambient Air 

Quality Standards (NAAQS).

ADEQ performed conservative forecasts of SO2 emissions from 2011 to 2030 through the 

utilization of point source facility PTE values (held constant), in place of actual emissions. The 

areas of the inventory which could be reasonably associated with population growth are Area (nonpoint) Sources excluding fires, On-Road Mobile Vehicle Sources (through the use of MOVES), 
12

and Non-Road Mobile Vehicle Sources. The emissions from these source categories were grown 

for future years based on the population projected growth factor shown in Table 8. Point source 

emissions (PTE), wildfire and prescribed fire emissions within the Morenci SO2 Maintenance Area 

and the 50 km buffer (Table 5 and 6) are assumed to remain constant through 2030. From Table 9 

it can be seen that from 2015 to 2030, the tons per year of SO2 increased by only 0.04 tons. This 

small change is due mainly to the small increase in population (2.2%) over the same period and the 

assumption that emissions from fires and the two industrial point sources did not change.

 

Table 8: Morenci SO2 Maintenance Area 2011 – 2030 Population Projection 

Morenci SO2 Maintenance Area Population Projection

Source Category 2011 2015 2020 2025 2030

Period 2011-2015 2016-2020 2021-2025 2026-2030

Morenci CDP 1,482 1,489 1,500 1,508 1,512

Clifton 3,273 3,299 3,323 3,340 3,350

Morenci Maintenance

Area 4,755 4,788 4,823 4,848 4,862

Greenlee County 8,380 8,437 8,499 8,543 8,568

Population projected 

growth factor 0.68% 0.73% 0.53% 0.29%

Source: Arizona Department of Administration (ADOA) http://www.workforce.az.gov/population-projections.aspx

Onroad Emissions Projections 

EPA considers on-road emissions from the NEI as a more accurate emissions estimate than onroad emissions calculated using MOVES with the default database. Therefore, it was decided to 

run MOVES for 2011, 2015, 2020, 2025, and 2030 using the national default database and ratio 

the 2011 MOVES results to 2011 NEI Version 1. The MOVES ratio (MR) is then applied to the 

2015, 2020, 2025 and 2030 (default database) MOVES runs. See the following equations for 

mathematical details.

MR2011 = MOVES ratio = 2011 NEI Version 1 to 2011 MOVES SO2 Ratio 

= M2011NEI / M2011RUN

Where:

M2011NEI = Greenlee County Onroad Mobile emissions as determined from the 

2011 NEI Version 1 = 0.58 tons/yr.

M2011RUN = Greenlee County Onroad Mobile emissions as determined by running MOVES using

the 2011 national default database = 0.88 tons/yr.

MR2011 = MOVES ratio = 0.58 tons/yr. / 0.88 tons/yr. = 0.657
13

Once the NEI to MOVES national default ratio is determined, that ratio can then be applied to 

subsequent year MOVES national default runs to estimate emissions for Greenlee County. An 

example calculation is provided below.

ORGC2015 = On-road emissions (Greenlee County) 2015 = M2015RUN x MR2011 ratio =

0.81 tons/yr. x 0.657 = 0.53 tons/yr.

Once the Greenlee County emissions are calculated, those emissions can then be allocated to the 

Morenci Maintenance Area by using the same population adjustment ratio (0.5674) that was 

calculated as shown in Section 1.2.1. An example calculation for determining onroad emissions 

for the Morenci Maintenance Area for 2015 is provided below.

ORMMA2015 = On-road emissions (Morenci Maintenance Area) 2015 = 

ORGC2015 x Population ratio Morenci Maintenance Area to Greenlee County = 

0.53 x 0.5674 = 0.30 tons/yr.

3.1 Summary of Emissions Projections for 2011 – 2030

This TSD describes the methodologies utilized in developing updated emission inventories for 

the Morenci SO2 Maintenance area. A baseline emission inventory was developed for the year 

2011 and serves as a base for projecting emissions through 2030. The projection of the Emission 

Inventory from 2011 to 2030 was performed by increasing portions or the entirety of each 

category: On-road Vehicle Emissions, Non-road Vehicle Emissions, and Area (non-point) 

emissions. Both non-road and area source emissions were grown using the population projected 

growth factors shown in Table 8. The resultant emissions are shown in Table 9. Between 2011 

and 2030, emissions are shown to have potentially increased by 6.8% compared to 2011 

emissions. The majority of this increase is attributed to growth in emissions from permitted 

point sources due to the use of PTE for future years compared to actual emissions from the 

baseline year. 
14

Table 9: Morenci SO2 Maintenance Area 2011 – 2030 Projected Emission Estimates

Morenci Maintenance Area SO2 Emissions (tons per year)

Source Category 2011 2015 2020 2025 2030 Projection Method

On-Road Vehicle Sources 0.33 0.30 0.30 0.31 0.33 MOVES

Non-Road Vehicle Sources 

(Locomotives) 0.05 0.05 0.05 0.05 0.05 Population

Non-Road Vehicle Sources 

(Other) 0.03 0.03 0.03 0.03 0.03 Population

Industrial (point) Sources 48.54 87.60 87.60 87.60 87.60 No change

Area (non-point) Sources 

(Fires) 525.67 525.67 525.67 525.67 525.67 No change

Area (non-point) Sources 

(Other) 0.27 0.27 0.27 0.28 0.28 Population

Total 574.89 613.92 613.92 613.94 613.96
15

4. REFERENCES

2011NEI: National Emission Inventory (NEI), 2011 Arizona and New Mexico Emission Report

http://www.epa.gov/ttnchie1/net/2011inventory.html

Air Quality Division, Arizona Department of Environmental Quality: “MORENCI SULFUR 

DIOXIDE NONATTAINMENT AREA STATE IMPLEMENTATION AND MAINTENANCE 

PLAN”, June 2002

2011ADOA: http://www.azstats.gov/population-estimates.aspx , 2013-2050 SUB-COUNTY 

POPULATION PROJECTIONS, “Greenlee.xlsx”

2002Morenci: “MORENCI SULFUR DIOXIDE NONATTAINMENT AREA STATE 

IMPLEMENTATION AND MAINTENANCE PLAN”, June 2002
Page Intentionally Left Blank
Appendix D

Morenci Modeling Analysis
Page Intentionally Left Blank
Modeling 

Analysis

Maintenance Plan 

for the Morenci 

Sulfur Dioxide 

Planning Area (1971 

NAAQS)

Arizona Department of 

Environmental Quality
Modeling Analysis

1.0 Overview of Modeling Approach 

The standard EPA screening dispersion model, AERSCREEN (version 11126) was used 

to estimate the impact of SO2 sources in or near the Morenci nonattainment area. 

AERSCREEN is the screening version of AERMOD, the EPA’s preferred model for 

near-field dispersion. AERSCREEN generates estimates of “worst-case” 1-hour

concentrations for a single source, without the need for hourly meteorological data, and 

also includes conversion factors to estimate “worst-case” 3-hour, 8-hour, 24-hour, and 

annual concentrations. AERSCREEN is intended to produce concentration estimates that 

are equal to or greater than the estimates produced by AERMOD with a fully developed 

set of meteorological and terrain data. According to the EPA’s memorandum dated April 

11, 2011, AERSCREEN has replaced SCREEN3 as the recommended screening model.

The AERSCREEN model consists of two main components: 1) the MAKEMET 

program; and 2) the AERSCREEN command-prompt interface program. The 

MAKEMET program generates application-specific worst-case meteorology using 

representative ambient air temperatures, minimum wind speed, and site-specific surface 

characteristics (albedo, Bowen ratio, and surface roughness). The AERSCREEN 

program interfaces with AERMAP (terrain processor in AERMOD) and BPIPPRM 

(building downwash tool in AERMOD) to process terrain and building information 

respectively, and interfaces with the AERMOD model utilizing the SCREEN option to 

perform the modeling runs. 

Based on the emission inventories as shown in 3.0, the two largest sources in and within 

50 kilometers of the Morenci nonattainment area were modeled. The sources modeled 

were the Freeport-McMoRan Morenci Mine (FMMM) with a PTE of 88 tons/year and 

the Freeport-McMoRan Safford Mine (FMSM) with a PTE of 81 tons/year. No other 

point sources were modeled because of their low or negligible emissions. The emission 

inventory represented in 3.2 lists several S02 sources within the 50K buffer with PTE 

above 5 TPY. Closer inspection of the individual point sources indicates many are 

emergency generators with actual emission less that 1 TYP and therefore considered 

negligible to this exercise. The modeling analysis included the following major steps: 

 Collected SO2 source information including emission rates, locations, and release 

parameters by reviewing the FMMM’s Title V permit and the FMSM’s Class II 

permit. 

 Determined representative minimum ambient temperature, maximum ambient 

temperatures, and minimum wind speed by reviewing the meteorological data 

collected from the Morenci/Safford area. Ran AERSURFACE to generate sitespecific surface characteristics (albedo, Bowen ratio, and surface roughness). Ran 

MAKEMET to generate site-specific worst-case meteorology. 

 Downloaded the USGS Digital Elevation Model (DEM) data. Ran the AERMAP 

terrain processor to take the terrain features into account. 
 Modeled FMMM and FMSM separately. Representative background 

concentrations were added to modeled impacts and the total concentrations were 

then compared to the NAAQS. 

 Estimated the cumulative impacts of the two facilities on the Morenci 

nonattainment area. 

2.0 Modeling for Freeport-McMoRan Morenci Mine (FMMM)

2.1 Source Inputs 

All SO2 sources along with their maximum allowable emissions are listed in Table 1. 

Blasting is the dominant source in FMMM, as the emission from blasting activities 

account for 99 percent of the total facility emission. Other emission sources include SO2

tanks, small industrial boilers, and steam boiler and turbine units. The total maximum 

allowable emission for these small sources is less than 1 ton/year. Table 2 summarizes 

stack release parameters for SO2 sources. Since Units 1-2 gas turbines and boilers have 

comparable release parameters, these four sources were combined together and modeled 

as a single point source. Similarly, SO2 tanks and small industrial boilers were combined 

together and modeled as another single point source. 

Table 2.1 SO2 Sources in the FMMM facility 

Operations Emission rate (tons/year) Note 

Blasting 86.75

SO2 Tank #1 0.01

SO2 Tank #2 0.01

Unit 1 gas turbine 0.33

Unit 1+Unit 2 gas turbine <=0.33

Unit 1+Unit 2 boiler <=0.13

Unit 1 boiler 0.13

Unit 2 gas turbine 0.33

Unit 2 boiler 0.13

Small Industrial Boiler #1 0.13

Boiler#1+#2+#3+#4+#5 <=0.33

Small Industrial Boiler #2 0.13

Small Industrial Boiler #3 0.13

Small Industrial Boiler #4 0.13

Small Industrial Boiler #5 0.13

Natural gas start up boiler 0.02

Table 2.2 Stack Release Parameters for SO2 Sources 

Operations Stack height

(m)

Stack diameter

(m)

Exit velocity

(m/s)

Exit gas 

temperature

(K)

Blasting N/A N/A N/A N/A

Unit 1 gas turbine 24.4 2.1 19.8 310.9

Unit 1 boiler 21.3 2.4 19.8 310.9

Unit 2 gas turbine 24.4 2.1 19.8 310.9

Unit 2 boiler 21.3 2.4 19.8 310.9

Small Industrial Boiler #1 10.1 7.3 11.6 419.3

Small Industrial Boiler #2 10.1 7.3 11.6 419.3
Small Industrial Boiler #3 10.1 7.3 11.6 419.3

Small Industrial Boiler #4 10.1 7.3 11.6 419.3

Small Industrial Boiler #5 10.1 7.3 11.6 419.3

Natural gas start up boiler N/A N/A N/A N/A

SO2 Tank #1 N/A N/A N/A N/A

SO2 Tank #2 N/A N/A N/A N/A

2.2 Modeling Blasting Operations

Blasting operations generate instantaneous emissions of gaseous pollutants including 

SO2. Historically, ADEQ has used the Open burn/Open Detonation Model (OBODM), 

developed by Strategic Environmental Research and Development Program (SERDP), to 

assess impacts from blasting sources. However, upon the review of the OBODM 

technical documents, it was found that that the OBODM model may not be appropriate 

for the screening modeling purposes. As the buoyant rise of a plume from a detonation in 

OBODM strongly depends on the quantity of material detonated, modeling the blasting 

operations as a single volume source may result in an extremely high plume rise and thus 

significantly underestimate the ground level impact. An extreme case occurs when the 

calculated plume height for the imaginary source is far above the top of the surface 

mixing layer, leading to a zero ground level concentration. This is because OBODM 

assumes the concentration contribution from the plume material that resides above the top 

of the surface layer can be neglected. Based on the discussions above, the OBODM 

model was not used in this modeling analysis. Instead, AERSCREEN was used to 

conservatively estimate the impacts from the blasting operations. 

Blasting operations vary spatially over the mining area. For screening modeling 

purposes, the blasting activities were assumed to be limited to a 200 by 200-meter area 

and were modeled a single volume source. Furthermore, a vertical dimension of 30-

meter was assumed to represent a conservative estimate of the averaging vertical 

dimension of a typical blast release. To model a volume source, three parameters 

including the release height, the initial lateral dimension (σyo), and the initial vertical 

dimension (σzo) of initial plume must be defined. According to USER’S GUIDE FOR 

THE AMS/EPA REGULATORY MODEL – AERMOD, EPA 2004a, the initial lateral 

dimension (σyo) and the initial vertical dimension (σzo) were estimated by the following 

equations:

σyo = horizontal dimension of source divided by 4.3 = 200/4.3 = 46.51 meters (Eq. 1)

σzo = vertical dimension of source divided by 2.15 = 30/2.15 = 13.95 meters (Eq.2)

The release height was determined as 15 meters, the height of the center of the volume 

source. 

3.0 Meteorological Data 

Minimum Wind Speed 
One of the key meteorological parameters for the AERSCREEN inputs is the minimum 

wind speed. The default minimum wind speed in AERSCREEN is 0.5 m/s. However, 

this number may be over conservative for modeling 24-hour average SO2 impacts 

because a wind speed of 0.5 m/s for continuous 24-hours will represent unrealistic wind 

conditions in the area of concern. Therefore, the available meteorological data in the 

Safford/Morenci area were reviewed and the site-specific minimum wind speed was 

determined. 

Three meteorological data sets are available in the Safford/Morenci area:

 ASOS at the Safford Regional Airport (SAD) station: The SAD station was 

installed in 1997 and the first available meteorological data set was available in 

1998. Currently ADEQ has four-year AERMET pre-processed meteorological 

data sets for SAD (2001-2004). As shown in Figure 1, 8.2 percent of the hourly 

wind speeds fell below 1.5 m/s and 5.7 percent of the data was missing. For wind 

speed observations less than 1.5 m/s, the SAD data sets report them as zero

(hourly “calm” observations). Dispersion under calm or missing wind conditions

is not modeled in AERMOD. 

 Safford AZMET station: The Arizona Meteorological Network (AZMET) began 

full operation in January of 1986 with the mission to provide meteorological data 

and weather-based information for agricultural and horticultural interests 

operating in southern and central Arizona. The Safford AZMET data are the most 

complete data sets available in the Safford area. However, the issue with the 

AZMET data is that the anemometer height is 10 feet, not 10 meters. Moreover,

since this station is located in a flat lower agricultural area, the Safford AZMET 

wind data may not represent the wind speeds in a mountainous area where 

FMMM and FMSM are located. 

 Freeport-McMoRan Safford Mine (FMSM) station: As part of the permitting 

effort, FMSM began collecting meteorological data at the project site in October 

1993. The most complete one-year period of on-site data is from November 8, 

1995 to November 7, 1996. These data have been reviewed and approved by 

ADEQ for the NAAQS modeling demonstration. As shown in Figure 1, 4.7

percent of the observations are calm (0 m/s) and 6.8 percent of the observations 

lie in the range from 0 m/s to 1.5 m/s. 

As presented above, a small percentage of hourly wind speeds in the Safford/Morenci

area are below 1.5 m/s. Moreover, in the Morenci maintenance plan renewal, the 

averaging time being assessed is 24-hours and annual rather than 1-hour. Therefore, a 

wind speed of 1.5 m/s was used for the AERSCREEN modeling. It is believed that this 

wind speed should provide a reasonable but still conservative estimation for modeling 24-

hour average and annual impacts. 
Safford Regional Airport (Years 2001-2004)

5.7%

8.2%

28.1%

25.7%

17.0%

8.1%

4.2%

3.1%

0%

5%

10%

15%

20%

25%

30%

Missing <1.5 1.5-3.0 3.0-4.5 4.5-6.0 6.0-7.5 7.5-9.0 >9.0

Hourly Wind Speed (m/s)

Percentage 

FMSM (Year 1996)

4.7%

6.8%

20.4% 19.7% 20.4%

12.4%

7.9% 7.7%

0%

5%

10%

15%

20%

25%

0 0-1.5 1.5-3.0 3.0-4.5 4.5-6.0 6.0-7.5 7.5-9.0 > 9.0

Hourly Wind Speed (m/s)

Percentage 

Figure 3.1 Hourly Wind Speed from Safford Regional Airport and FMSM Stations
Land Use Analysis

When applying the MAKEMET program to prepare the meteorological data for 

AERSCREEN, the values for three surface characteristics including surface roughness, 

albedo, and Bowen ratio must be determined. The surface roughness relates the height of 

obstacles to the wind flow and is, in principle, the height at which the mean horizontal 

wind speed is zero. The surface roughness length influences the surface shear stress and 

is an important factor in determining the magnitude of mechanical turbulence and the 

stability of the boundary layer. The albedo is the fraction of total incident solar radiation 

reflected by the surface back to space without absorption. The daytime Bowen ratio, an 

indicator of surface moisture, is the ratio of sensible heat flux to latent heat flux and is 

used for determining planetary boundary layer parameters for convective conditions 

driven by the surface sensible heat flux. 

Estimates of the surface characteristics were made with 1 km of an imaginary FMMM 

blasting site using EPA’s AERSURFACE program. Surface characteristics were 

developed based upon twelve sectors by season. The detailed setup is shown below. 

Land Cover input file opened: arizona_NLCD_090600_erd.tif

AERMET-formatted output file opened: morenci_surface

Type of Coordinates Entered: LATLON

Latitude (decimal degrees): 33.110000

Longitude (decimal degrees): -109.390000

Datum: NAD83

Study Radius for surface roughness (km): 1.0

Is surface roughness varied by sector? Y

# Sectors = 12

Sector beginning directions: 0 30 60 90 120 150 180 210 240 270 300 330

Temporal resolution (ANNUAL, MONTHLY, SEASONAL): SEASONAL

Continuous snow cover for most of the winter? N

Is site located at an airport? N

Is site considered an arid region? Y

Characterization of surface moisture at site: Average

Log file opened: morenci_surface.log

4.0 Receptors 

Based on the scaled FMMM facility map, the minimum distance to ambient air was 

determined as 1 km. This is the shortest distance from the potential blasting areas to the 

FMMM property boundary. The probe distance was set to 10 km. Two receptor spacing 

values were used: 25-m from 1 km to 5 km; and 50-m from 5 km to 10 km. 

4.1 Terrain Data

Given the complex topography of the Morenci nearby area, the terrain features were 

taken into consideration in the modeling analysis. USGS 1/3 arc-second (~10m

resolution) DEM data were used to extract the elevations of receptors and sources. 

All AERSCREEN model inputs are summarized in Table 3. 
Table 4.1 Inputs for Modeling FMMM Blasting Operations 

Parameters Inputs Input values

Source Source type Volume

Source emission rate 2.5 g/s

Initial lateral dimension 46.50 m

Initial vertical dimension 13.95 m

Volume height 15 m

Building Include building downwash No

Meteorology Minimum temperature 272 k

Maximum temperature 311 k

Minimum wind speed 1.5 m/s

Anemometer height 10 m

Source of surface characteristics AERSURFACE 

Terrain Include terrain Yes 

Coordinate type Latitude and longitude 

Source latitude 33.11 ̊

Source longitude -109.39 ̊

NAD 83

Initial Probe distance 10000 m 

Source elevation 1700 m

Override input elevation with AERMAP derived value No

Other Inputs Rural/Urban Rural

Minimum ambient distance 1000 m

Use flagpole receptors No

Use discrete receptors No 

4.2 Background Concentration 

Other than the FMMM facility itself, there are no other major sources of gaseous 

pollutants in this area. Consequently, background concentrations for the NAAQS 

modeling analysis should represent “natural” background concentrations. The historical 

SO2 monitoring data from San Manuel, Pinal County and Page, Coconino County were 

taken to determine the “natural” background concentrations (Table 4). The San Manuel 

data for Years 2005-2007 were collected after the closure of the San Manuel copper 

smelter and thus may represent the “natural” background concentrations for rural areas. 

The Page data also have been used by ADEQ as the recommended SO2 background

concentrations for rural areas if the actual measurements are not available. The 

background concentrations for 24-hour and annual SO2 were calculated by averaging the 

maximum measurements over the 3-years of available data from the two monitors. This 

results in a 24-hour background concentration of 20 μg/m3and an annual background 

concentration of 5 μg/m3, respectively. 

Table 4.3 Background Concentrations for 24-hour and Annual SO2
Monitoring Station Year Maximum 24-hour 

average conc. (μg/m3)

Annual conc. (μg/m3)

San Manuel, Pinal County

2007 10 6

2006 17 5

2005 8 5

Page, Coconino County

1998 24 4

1999 17 2

2000 7 1

Background 20 5

5.0 Results 

The modeling results for FMMM are summarized in Table 5. As shown in Table 5, these

sources will not cause SO2 NAAQS exceedances in the Morenci nonattainment area. 

Blasting is the dominant contributor to the modeled SO2 impacts while the impacts from 

other sources are nearly negligible. Since blasting was modeled as a surface-based 

volume source, the modeled maximum concentrations occurred in or near the property 

boundary of FMMM. 

Table 5.1 Modeling Results for FMMM

Source Average

Modeled 

conc. 

(μg/m3)

Facilitywide 

modeled 

conc. 

(μg/m3)

Background 

conc. (μg/m3)

Total 

conc. 

(μg/m3)

NAAQS 

(μg/m3)

% 

Standard

Blasting

24-hour

150.6

151.5 20 171.5 365 47% Units 1-2 

turbine/boiler 0.74

Other sources 0.17

Blasting

Annual

25.1

25.3 5 30.3 80 38% Units 1-2 

turbine/boiler 0.12

Other sources 0.03
5.1 Modeling for Freeport-McMoRan Safford Mine (FMSM)

Freeport-McMoRan Safford Mine (FMSM) is located approximately 13 km northnortheast of Safford, Graham County. Construction of the facility began in 2006 and the 

operations consist of open-pit mining, metallic minerals crushing, heap leach, solution 

extraction/electrowining (SE/EW), and sulfur burning & acid production. 

Table 6 lists all FMSM SO2 sources along with their maximum allowable emissions and 

related release parameters. There are two major sources within the FMSM facility, one is 

blasting and the other is sulfur burning & acid production. The combined emissions from 

the two sources account for approximately 97 percent of the total facility emission. Other 

emission sources include small industrial generators, heaters, boilers, and firewater pump. 

The total maximum allowable emission for these minor sources is only 1.6 tons/year,

Table 5.2 SO2 Sources in the FMSM facility 

The modeling methodology for the blasting source in FMSM was identical to that of 

FMMM with one exception, different size of the blasting area. As FMSM is much 

smaller than FMMM, the blasting area in FMSM was assumed to be 100 by 100 meters. 

The sulfur burning & acid production plant was modeled as a point source. Other minor 

sources were combined together and modeled as a single point source. Based on the 

scaled facility map of FMSM, the minimum distance to ambient air for blasting, sulfur 

burning& acid production, and other minor sources was determined as 1 km, 2.4 km, and

2.4 km, respectively. 

The minimum temperature, the maximum ambient temperature, and the minimum wind 

speed used were identical to those previously presented in the FMMM modeling. A 

separate AERSURFACE run was conducted to calculate site-specific surface 

characteristics when modeling blasting and the sulfur burning& acid production 

individually. 

All model inputs for blasting and sulfur burning & acid production are summarized in 

Table 7 and Table 8, respectively. 

Operations Emission rate

(tons/year)

Stack 

height

(m)

Stack 

diameter

(m)

Exit 

velocity

(m/s)

Exit gas 

temp.

(k)

Blasting 31.03 N/A N/A N/A N/A

Sulfur Burning & Acid Production 48.4 38.1 1.07 29.25 302.6

Generators #1 0.05 6.1 0.30 103.75 645.4

Generator #2 0.0117 6.1 0.30 103.75 645.4

Firewater Pump #1 0.0099 6.1 0.15 24.63 804.3

Firewater Pump #2 0.019 6.1 0.15 24.63 804.3

Sulphur pre-heater 1.13 12.2 0.91 13.65 783.2

Sulphur Furnace Startup Boiler 0.38 7.0 0.30 10.88 505.0

Hot Water Heater 0.015 6.1 0.30 13.78 455.4
Table 5.3 Inputs for Modeling FMSM Blasting Operations 

Parameters Inputs Input values

Source Source type Volume

Source emission rate 0.892 g/s

Initial lateral dimension 23.26 m

Initial vertical dimension 13.95 m

Volume height 15 m

Building Include building downwash No

Meteorology Minimum temperature 272 k

Maximum temperature 311 k

Minimum wind speed 1.5 m/s

Anemometer height 10 m

Source of surface characteristics AERSURFACE 

Terrain Include terrain Yes 

Coordinate type Latitude and longitude 

Source latitude 32.96 ̊

Source longitude -109.67 ̊

NAD 83

Initial Probe distance 10000 m 

Source elevation 1230 m

Override input elevation with AERMAP derived value No

Other Inputs Rural/Urban Rural

Minimum ambient distance 1000 m

Use flagpole receptors No

Use discrete receptors No 

Table 5.4 Inputs for Modeling FMSM Sulfur Burning & Acid Production 

Parameters Inputs Input values

Source Source type Point 

Source emission rate 1.3923 g/s

Stack height 38.10 m

Stack inner diameter 1.07 m

Exit gas velocity 29.25 m/s

Exit gas temperature 302.6 k

Building Include building downwash No

Meteorology Minimum temperature 272 k

Maximum temperature 311 k

Minimum wind speed 1.5 m/s

Anemometer height 10 m

Source of surface characteristics AERSURFACE 

Terrain Include terrain Yes 

Coordinate type Latitude and longitude 

Source latitude 32.93 ̊

Source longitude -109.705 ̊

NAD 83

Initial Probe distance 10000 m 

Source elevation 1230 m

Override input elevation with AERMAP derived value No

Other Inputs Rural/Urban Rural

Minimum ambient distance 2400 m

Use flagpole receptors No

Use discrete receptors No 
AERSCREEN was run to model each source (blasting, sulfur burning & acid production, 

and other sources) separately and then the maximum impacts from each model run were 

summed up to determine an overall impact from FMSM (regardless of different impact 

locations at different times). The modeling results for FMSM are summarized in Table 9. 

As shown in Table 9, the sources in FMSM will not cause SO2 NAAQS exceedances. 

The modeled impact from the blasting source was higher than that from the sulfur 

burning & acid production, mainly due to a relative lower release height. 

Table 5.5 Modeling Results for FMSM

Source Average

Modeled 

conc. 

(μg/m3)

Facilitywide 

modeled 

conc. 

(μg/m3)

Background 

conc. 

(μg/m3)

Total 

conc. 

(μg/m3)

NAAQS 

(μg/m3)

% 

Standard

Blasting

24-hour

66.9

112.5 20 132.5 365 36% Sulfur burning &

acid production 44.6

Other sources 0.97

Blasting

Annual

11.2

18.8 5 23.8 80 30% Sulfur burning & 

acid production 7.4

Other sources 0.16

6.0 Cumulative Impact Discussion

6.1 Cumulative Impacts of FMMM and FMSM on the Morenci Nonattainment Area

Figure 2 shows the locations of the Freeport-McMoRan Morenci Mine (FMMM) and 

Freeport-McMoRan Safford Mine (FMSM) relative to the Morenci Nonattainment area. 

FMMM is located within the nonattainment area while FMSM is about 20 km outside of 

the nonattainment area. As presented in Section 4.2, the maximum 24-hour average and 

annual average impacts of FMMM on the Morenci Nonattainment area were 151.5 μg/m3

and 25.3 μg/m3respectively, which occurred in or near the property boundary of FMMM. 

To estimate the cumulative impacts, the impacts of FMSM on the nonattainment area 

must be determined. 

In the AERSCREEN model run, a probe distance (10 km) was used, thus allowing the 

calculation of the maximum concentration for a given distance less than or equal to 10 

km. The results are shown in Figure 3. As indicated in Figure 3, the modeled 

concentration dropped rapidly with the increasing of the distance. For the receptors that 

were located at 10 km away from either facility, the maximum modeled 24-hour 

concentration was less than 20 μg/m3. Since the shortest distance from FMSM to the 

nonattainment area is around 20 km, the impacts of FMSM to the nonattainment area 

should be far below 20 μg/m3. As the ratio of the 24-hour average concentration to the 

annual average concentration in AERSCREEN is fixed at 6.0, the annual impact of 

FMSM on the nonattainment area should be much lower than 3.3 μg/m3. Furthermore, as 

the distance between FMSM and FMMM is around 30 km, the impacts of FMSM on the 
FMMM surrounding area are expected to be insignificant. In other words, the impacts 

from FMMM itself dominate the cumulative impacts on the Morenci non-attainment area. 

Figure 6.1 Locations of FMSM and FMMM relative to the Morenci Nonattainment 

Area

To be conservative, it was assumed that the maximum 24-hour average and annual 

average impacts of FMSM on the Morenci Nonattainment area were 20 μg/m3and 3.3 

μg/m

3

, respectively. Based on this conservative assumption, the cumulative impacts of 

FMMM and FMSM on the Morenci nonattainment area were estimated and the results 

are summarized in Table 10. The cumulative impacts were 53 percent and 42 percent of 

the 24-hour and annual NAAQS, respectively. 

FMSM

FMMM
FMMM

0

20

40

60

80

100

120

140

160

0 2000 4000 6000 8000 10000

Distance (m)

24-hour Concentration (ug/m3)

FMSM

0

20

40

60

80

100

0 2000 4000 6000 8000 10000

Distance (m)

24-hour Concentration (ug/m3)
Figure 6.2 Modeled Maximum 24-hour Concentration vs. Distance from Facilities to

Receptors 

Table 6.1 Cumulative Impacts of FMMM and FMSM on the Morenci 

Nonattainment Area

Facility Average

Max. impact on 

Morenci nonattainment area

(μg/m3)

Total 

modeled 

conc. 

Background 

conc. 

(μg/m3)

Total 

conc. 

(μg/m3)

NAAQS 

(μg/m3)

% 

Standard

FMMM

24-hour

151.5

171.5 20 191.5 365 53%

FMSM 20

FMMM

Annual

25.3

28.6 5 33.6 80 42 %

FMSM 3.3

6.2 Cumulative Impacts on the Morenci Nonattainment Area Boundary 

As shown in Figure 2, the shortest distance from the FMMM modeled source (blasting) 

to the Morenci nonattainment area boundary is around 10 km. Therefore, the maximum 

modeled 24-hour impact of FMMM on the boundary was 20 μg/m3 (see Figure 3). By 

using the fixed conversion ratio of 6.0 in AERSCREEN, the annual impact of FMMM on 

the boundary was estimated as 3.3 μg/m3. In combination with the impacts from FMSM 

as discussed in Section 4.4.1, the overall impacts for 24-hour average and annual average 

were 16 percent and 15 percent of the NAAQS, respectively (Table 11). 

Table 6.2 Cumulative Impacts of FMMM and FMSM on the Morenci 

Nonattainment Area Boundary 

Facility Average

Max. impact on 

Morenci nonattainment area

boundary 

(μg/m3)

Total 

modeled 

conc. 

Background 

conc. 

(μg/m3)

Total 

conc. 

(μg/m3)

NAAQS 

(μg/m3)

% 

Standard

FMMM

24-hour

20

40 20 60 365 16%

FMSM 20

FMMM

Annual

3.3

6.6 5 11.6 80 15 %

FMSM 3.3
7.0 Update of Modeling Analysis

The modeling analysis as presented in Sections 4.1-4.4 was conducted in Year 2012. It is 

necessary to verify if the previous modeling analysis is still valid because any significant changes 

in source inputs or modeling methodologies since Year 2012 may lead to significant changes in 

the model results. 

ADEQ issued a renewal permit to FMSM and FMMM in February 2012 and October 2013, 

respectively. Table 12 summarizes the potential to emit (PTE) of SO2 for FMSM and FMMM 

based on the two renewal permits. As shown in Table 12, there is no any change in SO2 emission 

limits for the two facilities. 

 Table 7.1 Emissions of SO2 for FMMM and FMSM in Renewal Permits 

Facility 

PTE in renewal permits (tpy) Modeled Emission (tpy)

Point Fugitive Total Point Fugitive Total 

FMMM 0.8 86.8 87.6 0.78 86.75 87.5

FMSM 50 31 81 50.02 31.03 81.05

The 2012 modeling analysis used AERSCREEN version 11126, which is still the most recent 

version of AERSCREEN (no updates). However, the AERSURFACE version (version 08009) 

used in the 2012 analysis has been updated to the new version 13016. A test run indicates that the 

two versions generated identical surface characteristic parameters. 

Another issue is related to the terrain data. The 2012 analysis used the Digital Elevation Model 

(DEM) data, which are no longer updated by the USGS. Instead, National Elevation Dataset 

(NED) data are being actively supported and checked for quality. Therefore, NED represents a 

more up-to-date and improved resource for terrain elevations for regulatory modeling purposes. 

In order to address this issue, a test run was performed to compare modeled concentrations from 

the FMMM’s blasting emissions by using the DEM data vs. the NED data. The results show that 

the modeled concentrations based on the DEM data and the NED data are nearly identical (150.6 

μg/m3vs. 150.2 μg/m3for 24-hour SO2). 

Based on the discussions above, it is concluded that the 2012 modeling analysis is still valid and 

no updates are needed. 
Appendix E.1

Notice of Public Hearing 
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Appendix E.2

Public Hearing Agenda
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AIR QUALITY DIVISION

HEARING ON PROPOSED 

Arizona State Implementation Plan Revision Maintenance Plan for the Morenci Dioxide Planning Area

(1971 NAAQS)

Morenci Community Center 438 Plaza Drive Morenci, AZ 85540

15, December and 15, 2014, at 1:00 p.m.

Pursuant to 40 CFR § 51.102 notice is hereby given that the above referenced meeting is open to the 

public. 

1. Welcome and Introductions

2. Purposes of the Oral Proceeding

3. Procedure for Making Public Comment

4. Brief Overview of the proposed SIP revision

5. Question and Answer Period

6. Oral Comment Period

7. Adjournment of Oral Proceeding

Copies of the proposal are available for review at the Arizona Department of Environmental Quality 

(ADEQ) Records Center, First Floor, 1110 W. Washington St., Phoenix, Arizona 85007, 1110 W. 

Washington St., Phoenix, Arizona, and http://www.azdeq.gov/environ/air/plan/index.html and at 

Clifton Public Library located at 102 School St., Clifton AZ 85533. For additional information 

regarding the hearing please call Adrian Peshlakai, ADEQ Air Quality Division, at (602) 771 - 6428 or 1-

800-234-5677, Ext. 771-6428. 

Upon request, the Department will provide appropriate auxiliary aids and services to persons with 

disabilities, at no charge, to assist in accessible communication to enable people who have speech, 

hearing, vision, learning, or other impairments to participate equally, including qualified sign language 

interpreters. To request an auxiliary aid or service, to obtain this document in alternative format, or for 

further information, please contact Alicia Pollard at (602) 771-4791 or via email at aap@azdeq.gov as 

early as possible to allow time to arrange the accommodation. TTY/TTD Services: 7-1-1. The ADA does 

not require the Department to take any action that would fundamentally alter the nature of it programs, 

services or activities, or impose an undue financial or administration burden on the Department.
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Appendix E.3

Public Hearing Sign-In Sheet
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Appendix E.4

Public Hearing Officer Certification and Transcript
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1

1 PUBLIC HEARING ON THE PROPOSED ARIZONA STATE 

2 IMPLEMENTATION PLAN REVISION MAINTENANCE PLAN for the 

3 MORENCI SULFUR DIOXIDE PLANNING AREA (1971 NAAQS)

4

5 Oral Proceeding

6 December 15, 2014

7

8 Good afternoon, thank you for coming. I now open this hearing on the proposed Arizona State 

9 Implementation Plan Revision Maintenance Plan for the Morenci Sulfur Dioxide Planning Area 

10 (1971 NAAQS).

11

12 It is Monday, December 15, 2014; the time is 12:07. The location is the Morenci Community 

13 Center at 438 Plaza Drive Morenci Arizona 85540.

14

15 My name is Michael Orman, and I have been appointed by the Director of the Arizona 

16 Department of Environmental Quality (ADEQ) to preside at this proceeding.

17

18 The purposes of this proceeding are to provide the public an opportunity to:

19

20 1) hear about the substance of the proposed SIP;

21 2) ask questions regarding the SIP; and,

22 3) present oral arguments, data, and views regarding the SIP in the form of comments on the 

23 record. 
2

24

25 Adrian Peshlakai is here representing ADEQ from the Air Quality Division, State 

26 Implementation Plan Section.

27

28 Public notice appeared in the Copper Era and ADEQ’s website beginning November 12, 2014. 

29 Copies of the proposed SIP revision were made available at the ADEQ Records Center and 

30 ADEQ’s website and the Clifton, Arizona library beginning December 15, 2014.

31

32 As the purpose of the public hearing is to receive public from the public and there are no 

33 members of the public present this hearing is adjourned the time is 12:08.
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Appendix E.5

Responsiveness Summary
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RESPONSIVENESS SUMMARY

to

Testimony Taken at Oral Proceeding on the December, 2014 Proposed Arizona State 

Implementation Plan Revision

The oral proceeding on the December 2014, Proposed Arizona State Implementation Plan 

Revision, Maintenance Plan for the Morenci Sulfur Dioxide Planning Area (1971 NAAQS), was 

held on Monday December 15, 2014 at 1:00 p.m., at the Morenci Community Center located at 

438 Plaza Drive Morenci, AZ 85540. The Arizona Department of Environmental Quality 

(ADEQ) received no verbal or written comments on the proposed State Implementation Plan 

Revision.

No changes were made in response to the public comments, however, during its final review of 

the proposed State Implementation Plan Revision, ADEQ made typographical corrections to 

Table 1.4 and added insets in Figure 3.1 to clearly identify sources within the planning area. 

Other minor revisions were made for clarity, grammar and formatting.