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Daily Rules, Proposed Rules, and Notices of the Federal Government

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R09-OAR-2006-0580; FRL-8270-3]

Approval and Promulgation of Air Quality Implementation Plans; Designation of Areas for Air Quality Planning Purposes; Arizona; Miami Sulfur Dioxide State Implementation Plan and Request for Redesignation to Attainment; Correction of Boundary of Miami Sulfur Dioxide Nonattainment Area

AGENCY: Environmental Protection Agency (EPA).
ACTION: Direct final rule.
SUMMARY: EPA is taking direct final action under the Clean Air Act to approve the Miami Sulfur Dioxide Nonattainment Area StateImplementation and Maintenance Plan as a revision to the Arizona state implementation plan. The Arizona Department of Environmental Quality developed this plan to maintain the sulfur dioxide national ambient air quality standards in the Miami (Gila County) area. The maintenance plan contains various elements, including contingency provisions that will be implemented if measured ambient concentrations of sulfur dioxide are above certain trigger levels. EPA is also approving the State of Arizona's request for redesignation of the Miami area from nonattainment to attainment for the sulfur dioxide standards. Lastly, EPA is correcting the boundary of the Miami sulfur dioxide nonattainment area to exclude a noncontiguous township that was erroneously included in the description of the area and to fix a transcription error in the listing of one of the other townships.

EPA is taking these actions consistent with provisions in the Clean Air Act that obligate the Agency to approve or disapprove submittals of revisions to state implementation plans and requests for redesignation. The intended effect is to redesignate the Miami, Arizona sulfur dioxide nonattainment area to attainment, provide for maintenance of the standard for the ten-year period following redesignation, and correct long-standing errors in the codified description of the area.

DATES: This rule is effective on March 26, 2007 without further notice, unless EPA receives adverse comments by February 23, 2007. If we receive such comments, we will publish a timely withdrawal in theFederal Registerto notify the public that this direct final rule will not take effect.
ADDRESSES: 1.Federal eRulemaking Portal: www.regulations.gov.Follow the on-line instructions.

2.E-mail: vagenas.ginger@epa.gov.

3.Mail or deliver:Ginger Vagenas (Air-2), U.S. Environmental Protection Agency Region IX, 75 Hawthorne Street, San Francisco, CA 94105-3901.

Instructions:All comments will be included in the public docket without change and may be made available online atwww.regulations.gov,including any personal information provided, unless the comment includes Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Information that you consider CBI or otherwise protected should be clearly identified as such and should not be submitted through thewww.regulations.govor e-mail.www.regulations.govis an "anonymous access" system, and EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send e-mail directly to EPA, your e-mail address will be automatically captured and included as part of the public comment. If EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, EPA may not be able to consider your comment.

Docket:The index to the docket for this action is available electronically atwww.regulations.govand in hard copy at EPA Region IX, 75 Hawthorne Street, San Francisco, California. While all documents in the docket are listed in the index, some information may be publicly available only at the hard copy location (e.g., copyrighted material), and some may not be publicly available in either location (e.g., CBI). To inspect the hard copy materials, please schedule an appointment during normal business hours with the contact listed in theFOR FURTHER INFORMATION CONTACTsection.

FOR FURTHER INFORMATION CONTACT: Ginger Vagenas, Air Planning Office, (415) 972-3964 or by e-mail atvagenas.ginger@epa.gov.
SUPPLEMENTARY INFORMATION:

Elsewhere in thisFederal Register, we are proposing approval and soliciting written comment on this action. Throughout this document, the words “we,” “us,” or “our” mean U.S. EPA.

Table of Contents I. Summary of Today's Direct Final Action II. Introduction A. SO2NAAQS B. State Implementation Plan C. History of SO2Planning in Arizona 1. Development of the SO2SIP 2. Miami SO2Nonattainment Area D. Sources of SO2Emissions in the Miami Area III. CAA Requirements for Redesignation Requests and Maintenance Plans IV. EPA's Evaluation of Redesignation Request and Maintenance Plan for the Miami, Arizona SO2Nonattainment Area A. The Area Must Be Attaining the SO2NAAQS B. The Area's Applicable Implementation Plan Must Be Fully Approved Under Section 110(k) C. The Improvement in Air Quality Must Be Due to Permanent and Enforceable Reductions in Emissions D. The Area Must Have Met All Applicable Requirements Under Section 110 and Part D 1. Section 110 Requirements 2. Part D Requirements a. Section 172 b. Section 176 c. Subpart 5 E. The Area Must Have a Fully Approved Maintenance Plan 1. Attainment Inventory 2. Maintenance Demonstration 3. Monitoring Network 4. Verification of Continued Attainment 5. Contingency Plan 6. Subsequent Maintenance Plan Revisions 7. Conclusion V. Boundary Correction A. Background B. Authority for Correcting Errors C. Evaluation and Conclusion VI. Public Comment and Final Action VII. Statutory and Executive Order Review I. Summary of Today's Direct Final Action

On June 26, 2002, the Arizona Department of Environmental Quality (``ADEQ'' or ``State'') submitted to EPA Region IX its Miami Sulfur Dioxide State Implementation and Maintenance Plan and its request for redesignation to attainment (``Miami SO2Maintenance Plan” or ``submittal”). The submittal summarizes the progress the State has made in attaining the sulfur dioxide (SO2) national ambient air quality standards (NAAQS) in the Miami nonattainment area (Gila County, Arizona) (“Miami area”) and includes a plan to assure continued attainment of the SO2NAAQS for at least the next 10 years. The June 26, 2002 submittal also includes a request for redesignation of the boundary of the area and for redesignation of the status of the area, as amended, to “attainment” under section 107(d) of the Clean Air Act (“Act” or CAA). On June 30, 2004, ADEQ submitted certain replacement pages correcting errors in the June 26, 2002 submittal. On June 20, 2006, ADEQ submitted a letter withdrawing the boundary redesignation request and requesting EPA to address the boundary issue as an error correction under CAA section 110(k)(6) instead.

In today's direct final action, because we find that the Miami SO2Maintenance Plan meets the requirements for maintenance plans under section 175A of the Act and that the Miami area qualifies for redesignation under CAA section 107(d)(3)(E), we are approving the submittal (as amended by the submittals dated June 30, 2004 and June 20, 2006) as a revision to the Arizona SIP and redesignating the Miami area from nonattainment to attainment for the SO2NAAQS. Also, based on a review of the relevant State and EPA materials from the late 1970's, we are correcting errors under CAA section 110(k)(6) in the listing of the townships that comprise the Miami SO2nonattainment area to exclude a noncontiguous township andto fix a transcription error in one of the other townships so listed.

II. Introduction

The following section discusses the NAAQS for SO2, CAA requirements for state implementation plans, SO2planning in Arizona generally and in the Miami area more specifically, and sources of emissions in the Miami area.

A. SO2NAAQS

The NAAQS for SO2consists of three standards: Two primary standards for the protection of public health and a secondary standard for protection of public welfare. The primary SO2standards address 24-hour average and annual average ambient SO2concentrations. The secondary standard addresses 3-hour average ambient SO2concentrations. The level of the annual SO2standard is 0.030 parts per million (ppm), which is equivalent to 80 micrograms per cubic meter (μg/m3), not to be exceeded in a calendar year. The level of the 24-hour standard is 0.14 ppm (365 μg/m3), not to be exceeded more than once per calendar year. The level of the secondary SO2standard is a 3-hour standard of 0.5 ppm (1,300 μg/m3), not to be exceeded more than once per calendar year. See 40 CFR 50.2-50.5.

B. State Implementation Plan

The CAA requires states to implement, maintain, and enforce ambient air quality equal to or better than the NAAQS. A state's strategies for implementing, maintaining, and enforcing the NAAQS are submitted to EPA for approval, and, once approved, become part of the State Implementation Plan (or SIP) for that State. SIPs are compilations of regulatory and non-regulatory elements adopted, submitted, and approved at different times to address various types of changes in circumstances, such as new or revised NAAQS or amendments to the CAA. SIPs include, among other things, the following: (1) An inventory of emission sources; (2) statutes and regulations adopted by the state legislature and executive agencies; (3) air quality analyses that include demonstrations that adequate controls are in place to meet the NAAQS; and (4) contingency measures to be undertaken if an area fails to attain the standard or make reasonable progress toward attainment by the required date. The state must make proposed changes to the SIP available for public review and comment through a public hearing, and must formally adopt the changes before submitting them to EPA for approval. Upon our approval, a SIP revision becomes federally enforceable.

C. History of SO2Planning in Arizona 1. Development of the SO2SIP

In the early 1970's, soon after the Clean Air Amendments of 1970 were passed, Arizona began developing air quality regulations that applied to all Arizona primary copper smelters, including the one operating in the Miami area. These regulations focused on establishing an air quality monitoring network in the areas surrounding the smelters and determining the allowable emission rates from the smelters so that the SO2NAAQS could be attained and maintained. Arizona submitted various SIP revisions during the 1970s to establish approvable emission limitations for the primary copper smelters operating in the state. On September 20, 1979, the State submitted its SIP revision to EPA which contained its multi-point rollback (MPR) technique to establish operating limitations on smelters. After EPA's proposed conditional approval on November 30, 1981 (46 FR 58098), Arizona made necessary changes which corrected identified deficiencies. EPA granted full approval of the MPR-based SIP submittal on January 14, 1983 (48 FR 1717), but was not able to grant full approval to the SO2SIPs for six smelter areas (including Miami) because they lacked a strategy for addressing fugitive1 sources of SO2.

1

“Fugitive” in this context refers to emissions that could not reasonably pass through a stack, chimney, vent for a functionally equivalent opening.

On November 1, 2004, EPA approved several revisions to the SO2SIP, including site-specific requirements, compliance and monitoring, and fugitive emissions standards for existing primary copper smelters. See 69 FR 63321. In that same notice, EPA promulgated a limited approval/limited disapproval of R18-2-Appendix 8, which sets out procedures for calculating sulfur emissions using a sulfur balance method. ADEQ subsequently corrected the identified deficiencies and EPA approved the new version of R18-2-Appendix 8 as a SIP revision on April 12, 2006. See 71 FR 18624. The effective date for our April 12, 2006 final approval is June 12, 2006.

2. Miami SO2Nonattainment Area

Originally, the air quality planning area we refer to as the Miami SO2nonattainment area was not separately defined but rather was included in a county-wide SO2nonattainment area (see 43 FR 8969, March 3, 1978). At the request of the state of Arizona, the boundaries were reduced to nine townships in and around the city of Miami (44 FR 21261, April 10, 1979). See also, 40 CFR 81.303.2 In addition, six adjacent townships were designated as “cannot be classified”. Section 107(d)(1)(C) of the 1990 Clean Air Act Amendments (CAAA) brought forward, by operation of law, the nonattainment designations for areas, such as the Miami SO2area, that continued to be designated as nonattainment at the time of enactment of the CAAA, i.e., areas that had not been redesignated to “attainment” prior to November 1990.

2The nine townships that comprise the Miami SO2nonattainment area are: T2N, R14E; T2N, R15E; T1N, R13E (only that portion in Gila County); T1N, R14E; T1N, R15E; T1N, R16E; T1S, R14E (only that portion in Gila County); T1S, R141/4E; and T1S, R15E. Code of Federal Regulations, title 40, part 81, section 303 (40 CFR 81.303) also identifies six other townships as areas that “cannot be classified.” These six townships are: T2N, R13E (only that portion in Gila County); T2N, R16E; T1S, R13E (only that portion in Gila County); T1S, R16E; T2S, R14E (only that portion in Gila County); and T2S, R15E. All of the townships discussed in this notice relate to the Gila and Salt River Base Line. In section V of this notice, we discuss our decision to amend 40 CFR 81.303 to correct the boundary of the Miami area to exclude a noncontiguous township and to fix a typographical error.

D. Sources of SO2Emissions in the Miami Area

The dominant source of SO2emissions in the Miami area is the Phelps-Dodge Miami primary copper smelter (“Miami smelter”). Combined stack and fugitive SO2emissions from the smelter are limited under the source-specific EPA-approved rule (i.e., R18-2-7-715) to 2,420 pounds per hour annual average, which amounts to approximately 10,368 tons per year based on 357 days of operation (set forth for the permit for this facility) or approximately 10,600 tons per year assuming 365 days per year of smelter operation. Between 1996 and 2000, the smelter's actual SO2emissions ranged from 5,737 tons per year to 7,819 tons per year and represented 97 to 99% of the total stationary source SO2emissions in the Miami nonattainment area. See tables 4.1, 4.3, and 5.2 of the Miami SO2Maintenance Plan. There are several other point sources of SO2in the Miami area, all of which are relatively minor: BHP Copper, Pinto Valley; BHP Copper, Miami East Unit; Carlota Copper Company Mine; and the Phelps-Dodge Miami Mine. Viewed collectively, these sources are permitted to emit a total of approximately 100 tons per year. Actual emissions, however, are generally less than 10 tons per year. SO2emissions from area and mobile sourcesare about 150 tons per year. See sections 4.1 and 4.3 of the Miami SO2Maintenance Plan and table 1, below.

Table 1.—Point, Area, and Mobile Sources of SO2Emissions in the Miami SO2Nonattainment Area (Tons per year, TPY) Source name or type Allowable emissions Actual emissions (1999) Stationary Sources (not including Phelps-Dodge primary copper smelter): BHP Copper, Pinto Valley Unit 6a 1 BHP Copper, Miami East Unit 1 1 Carlotta Copper Company Mine 1 0 Phelps-Dodge Miami Mine 92 7 Area and Mobile NA 149 Phelps-Dodge Miami Smelting Operations 10,368 7,819 Total From All Sources NA 7,975 aWhen burning diesel; lower limits exist for other fuels. NA = not applicable. Source: Sections 4.1 and 4.3 from the Miami SO2Maintenance Plan. III. CAA Requirements for Redesignation Requests and Maintenance Plans

As stated in the summary section of this rule, Arizona has requested that we redesignate the Miami SO2nonattainment area to attainment. Any redesignation from nonattainment to attainment requires EPA to determine whether the requirements of Clean Air Act section 107(d)(3)(E), have been met. These criteria are: (1) At the time of the redesignation, we must find that the area has attained the relevant NAAQS; (2) the State must have a fully approved SIP for the area; (3) we must determine that the improvements in air quality are due to permanent and enforceable reductions in emissions resulting from implementation of the SIP and applicable federal regulations and other permanent and enforceable reductions; (4) the state must have met all the nonattainment area requirements applicable to the area; and (5) we must have fully approved a maintenance plan for the area under CAA section 175A.

To evaluate the State's redesignation request for the Miami area, we relied upon the Clean Air Act itself, particularly section 110 and part D (of title I), EPA's NAAQS and SIP regulations in 40 CFR parts 50 and 51, and guidance set forth in “General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990” (57 FR 13498, April 16, 1992), and in the following EPA guidance documents: “Procedures for Processing Requests to Redesignate Areas to Attainment,” dated September 4, 1992, from John Calcagni, (“Calcagni Memo”), “Attainment Determination Policy for Sulfur Dioxide Nonattainment Areas,” dated January 26, 1995, from Sally L. Shaver, (“Shaver Memo”), and “Part D New Source Review (part D NSR) Requirements for Areas Requesting Redesignation to Attainment,” dated October 14, 1994, from Mary D. Nichols (“Nichols Memo”).

IV. EPA's Evaluation of Redesignation Request and Maintenance Plan for the Miami, Arizona SO2Nonattainment Area A. The Area Must Be Attaining the SO2NAAQS

Under CAA section 107(d)(3)(E)(i), in order for an area to be redesignated, we must determine that the area has attained the applicable NAAQS. The air quality data should be representative of the area of highest concentration and should be measured by monitors that 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 part 58 and recorded in EPA's Air Quality System database (AQS) to be available for public review. Under 40 CFR part 58, States certify data that is entered into AQS on an annual basis.

For the purposes of determining whether an area has attained the SO2NAAQS, we require no fewer than two consecutive years of “clean” data (i.e., no violations) as recorded in AQS. In addition, to qualify for attainment determination purposes, the annual average and second-highest 24-hour average concentrations must be based upon hourly data that are at least 75 percent complete in each calendar quarter. See 40 CFR 50.4.

The State of Arizona initiated ambient monitoring of SO2in the Miami area in 1970. In order to establish coverage sufficient to evaluate the ambient impact of smelter emissions, this initial effort was expanded. Eventually more than sixteen stationary monitoring sites were established, with as many as seven monitors operating concurrently. Historic ambient SO2monitoring site locations and periods of operation are provided in Table 3.1, and Figures 3.1 and 3.2 of the State's submittal.

Following the Miami smelter's compliance with stack emissions limits (using continuous control technology) as required under Arizona Administrative Code (AAC) R9-3-515, which was submitted and approved by EPA as a revision to the Arizona SIP in the 1980's (but since amended and re-codified as R18-2-7-715), the number of SO2monitors has decreased. Between 1990 and 1996, the number of monitors varied from three to four and several monitoring locations changed, but since 1997, the three presently-operating monitors have remained at their current locations: the Jones Ranch monitor along Cherry Flats Road, the Ridgeline monitor along Linden Street, and the Townsite monitor along Sullivan Street.

All three presently-operating monitors are located south of the smelter, but vary in distance and elevation relative to smelter sources. The Townsite monitor lies closest to the smelter and at the lowest elevation among the three sites while the Jones Ranch monitor lies furthest from the smelter but at the highest elevation. The Jones Ranch and Townsite monitors are operated by Phelps Dodge using Thermal Electron pulsed fluorescent (TECO) samplers, and the Ridgeline monitor is operated by ADEQ using a Thermo pulse fluorescence analyzer.

Table 2 below summarizes the SO2monitoring data collected at the various monitors operated by ADEQ (or, in the case of Jones Ranch, ADEQ or the smelter operator) from 1988 through 2005. ADEQ ended its monitoring at Jones Ranch in 1994, but the smelteroperator continues to monitor SO2at that location. Table 3 below presents estimated annual SO2emissions from the smelter over the same time period.

Table 2.—Summary of Sulfur Dioxide Ambient Air Quality Data—Miami, Arizona: 1988-2005 Year Averaging period Concentrations (μg/m3) at individual sites Jones ranch Cities services bldg. Little acres Ridgeline 1988 Max 3-hour 655 413 153 Max 24-hour 180 73 29 Annual 21 13 6 1989 Max 3-hour 814 169 86 Max 24-hour 133 29 18 Annual 17 4 3 1990 Max 3-hour 715 Max 24-hour 136 Annual *16 1991 Max 3-hour 767 Max 24-hour 143 Annual *18 1992 Max 3-hour 875 Max 24-hour 128 Annual *8 1993 Max 3-hour 721 Max 24-hour 123 Annual 10 1994 Max 3-hour 566 Max 24-hour 121 Annual 16 1995 Max 3-hour 433 244 Max 24-hour 122 89 Annual 8 10 1996 Max 3-hour 593 338 Max 24-hour 146 110 Annual 11 8 1997 Max 3-hour 820 524 Max 24-hour 138 92 Annual 10 5 1998 Max 3-hour 840 175 Max 24-hour 123 40 Annual 10 8 1999 Max 3-hour 897 198 Max 24-hour 152 65 Annual 8 14 2000 Max 3-hour 895 307 Max 24-hour 133 70 Annual 11 17 2001 Max 3-hour 577 338 Max 24-hour 145 110 Annual 19 19 2002 Max 3-hour 628 174 Max 24-hour 184 78 Annual 16 18 2003 Max 3-hour 578 250 Max 24-hour 152 70 Annual 21 13 2004 Max 3-hour 326 291 Max 24-hour 99 78 Annual 13 11 2005 Max 3-hour 250 Max 24-hour 78 Annual 12 Notes:The primary NAAQS for SO2are 365 μg/m3, 24-hour average, not to be exceeded more than once per calendar year, and 80 μg/m3, annual average. The secondary NAAQS for SO2is 1,300 μg/m3, 3-hour average, not to be exceeded more than once per calendar year. The * indicates that the annual average does not satisfy summary criteria. The — indicates little or no data in a given year from a given monitor. EPA's AQS database is the source of data shown initalics. ADEQ's Air Quality Annual Reports are the sources of the non-italicized data shown in this table. Monitoring Sites: • The Jones Ranch monitoring site is located along Cherry Flats Road, approximately 1.8 miles south-southeast of the smelter stack at an elevation of 4,100 feet above sea level. ADEQ operated a monitor at this site through 1994. From 1991 through 1994, the State-operated monitor at Jones Ranch was referred to as “Nolan Ranch”. More recent data shown in this table for Jones Ranch was collected and compiled by the smelter operator. • The Cities Services Building monitoring site was located approximately 2.2 miles east-northeast of the smelter stack. ADEQ operated a monitor at this site through 1989.
• The Little Acres monitoring site was located approximately 2 miles southeast of the smelter. ADEQ operated a monitor at this site through 1989. • The Ridgeline monitoring site, which is the current ADEQ monitoring site for SO2in the Miami area, is located along Linden Street at an elevation of 3,600 feet. Table 3.—Miami Smelter Sulfur Dioxide Emissions: 1988-2005 Year Sulfur dioxide emissions tons per year 1988 3,988 1989 6,398 1990 4,141 1991 11,145 1992 4,813 1993 7,678 1994 9,260 1995 5,108 1996 5,737 1997 6,368 1998 6,097 1999 7,819 2000 6,810 2001 9,062 2002 5,667 2003 8,005 2004 8,754 2005 7,366 Sources: Miami SO2Maintenance Plan, page 35; e-mail correspondence from Bruce Friedl, ADEQ, dated September 29, 2006.

Review of historic data supports identification of the Jones Ranch monitor as the monitoring location where the highest concentrations are recorded among the network of monitoring locations selected to measure the impact of smelter-related emissions on ambient air quality. We note that the Jones Ranch monitoring site was determined to be the “limiting site” for the purposes of establishing emissions limits for the smelter. ADEQ closed its monitoring site at Jones Ranch in 1994, and while Phelps-Dodge continues to operate an SO2monitor at that site, the data is not recorded in AQS.3 In 1995, ADEQ began monitoring at the Ridgeline site, and no exceedances have ever been recorded there.

3ADEQ has committed to working with Phelps-Dodge to begin entering SO2monitoring data collected at the Jones Ranch site to AQS beginning with the first quarter of 2008. See letter from Nancy C. Wrona, Director, Air Quality Division, ADEQ, to Deborah Jordan, Air Division Director, EPA—Region IX, dated October 18, 2006.

Based on a review of the data from the Miami SO2Maintenance Plan as well as tables 2 and 3 presented above, we find that the Miami nonattainment area has attained the SO2NAAQS and thereby meets the first criterion for redesignation. Our conclusion is based on six basic interrelated facts:

• Ambient SO2concentrations in the Miami air quality planning area are determined by emissions from the Phelps-Dodge primary copper smelter4 and local meteorological and topographic characteristics, and all other SO2sources have essentially no effect on ambient levels in the planning area;

4There is one significant point source located outside the Miami nonattainment area but within 50 kilometers of the Miami nonattainment area. The ASARCO Hayden Smelter is located approximately 46 kilometers south of the Miami smelter. However, because the ASARCO Hayden smelter is geographically separated from the Miami area by the 7,000 foot Pinal Mountains, its emissions do not have an impact on air quality in the Miami area.

• The monitor at the Jones Ranch site records SO2concentrations that are representative of the highest ambient levels in the nonattainment area;

• There are two consecutive and complete years of “clean” data from the Jones Ranch monitor, i.e., the limiting site, as recorded in AQS (1988 and 1989);

• During the 1988-1989 period, maximum concentrations were approximately 60% of the 3-hour-average secondary NAAQS and approximately 50% of the 24-hour-average primary NAAQS, and the highest of the annual-average concentrations measured in the area during this period was approximately 30% of the corresponding primary NAAQS;

• While annual emissions from the smelter have varied from year to year, they have generally been no higher than 50% above those that occurred during the 1988-1989 period; and

• No SO2exceedances have been measured at any of the monitoring sites over the 1988 to 2005 period.

B. The Area's Applicable Implementation Plan Must Be Fully Approved Under CAA Section 110(k)

Under CAA section 107(d)(3)(E)(ii), the SIP for the Miami area must be fully approved under CAA section 110(k) of the Act. We examined the applicable SIP for Arizona and also looked at the disapprovals listed in 40 CFR 52.125 and have determined that no disapprovals listed remain relevant to the applicable SIP. Arizona has a fully approved SIP with respect to SO2in the Miami area.

C. The Improvement in Air Quality Must Be Due to Permanent and Enforceable Reductions in Emissions

CAA section 107(d)(3)(E)(iii) requires that EPA determine that the improvement in air quality is due to permanent and enforceable reductions in emissions resulting from implementation of the SIP and/or applicable federal measures. Figure 6.1 of the Miami SO2Maintenance Plan (as amended in ADEQ's submittal dated June 30, 2004) illustrates the significant decline in emissions from the Miami smelter since the 1970's in inverse proportion to the level of control over smelter emissions sources.

Control over the smelter's SO2emissions has been made permanent and enforceable through EPA approval of State rules limiting such emissions as a revision to the Arizona SIP (specifically, R18-2-715, R18-2-715.01, R18-2-715.02, and R18-2-Appendix 8) and through ADEQ's issuance of a title V permit for the Miami smelter. Arizona's primary copper smelter rules and ADEQ's title V permit contain enforceable emission limitations that cap emissions at a level that has been shown to be protective of the NAAQS. Any relaxation to the SIP-approved limits must be approved by EPA as a revision to the Arizona SIP, and EPA may not approve any such SIP revision without a demonstration that the relaxation in the limits would not interfere with attainment or maintenance of the NAAQS. See CAA section 110(l). Therefore, we find that the improvement in ambient SO2concentrations in the Miami, AZ area is due to permanent and enforceable reductions in emissions resulting from implementation of the SIP.

D. The Area Must Have Met All Applicable Requirements Under Section 110 and Part D

Under CAA section 107(d)(3)(E)(v), we must determine whether the State of Arizona has met all requirements under section 110 and under part D (of title I) of the CAA applicable to the Miami SO2nonattainment area.

1. Section 110 Requirements

CAA section 110 contains the general requirements for SIPs (enforceable emissions limits, ambient monitoring, permitting of new sources, adequate funding, etc.). EPA's guidance for implementing section 110 of the Act is discussed in the General Preamble to Title I (57 FR 13498, April 16, 1992). Over the years, we have approved Arizona's SIP as meeting these basic requirements. The SIP includes enforceable emission limitations; requires monitoring, compiling, and analyzing of ambient air quality data; requires preconstruction review of newmajor stationary sources and major modifications to existing ones; provides for adequate funding, staff, and associated resources necessary to implement its requirements; and requires stationary source emission monitoring and reporting.

2. Part D Requirements

Before an area can be redesignated to attainment, it must have fulfilled the applicable requirements under part D (of title I). For this area, the relevant requirements are found in subparts 1 and 5 of part D. Subpart 1 of part D specifies the basic requirements applicable to all nonattainment areas. Subpart 5 sets out additional provisions for areas designated nonattainment for SO2. As discussed below, EPA finds that Arizona has met the requirements of subpart 1 of part D, specifically sections 172(c) and 176, and subpart 5 as applicable for the Miami SO2nonattainment area.

a. Section 172

CAA section 172 contains the general requirements for nonattainment SIPs. A thorough discussion of the requirements of 172(c) can be found in the General Preamble for the implementation of title I (57 FR 13498, April 16, 1992). Additional guidance can be found in the Calcagni memo.

EPA has interpreted the requirements of CAA sections 172(c)(2) (reasonable further progress—RFP), 172(c)(6) (other measures), and 172(c)(9) (contingency measures) as not relevant to a redesignation request because they only have meaning for an area that is not attaining the standard (see the General Preamble and the Calcagni Memo), and as discussed above in section IV.A. of this notice, we find that the Miami area is attaining the SO2standard. Furthermore, the State has not sought to exercise options that would trigger section 172(c)(4) (identification of certain emissions increases). Thus, this provision is also not relevant to this redesignation request. The other provisions under 172(c) are discussed below.

Reasonably available control measures.Under CAA section 172(c)(1), reasonably available control measures (RACM), which include requirements for reasonably available control technology (RACT), are required for existing sources in nonattainment areas. In 1983, we approved the State's submittal of Rule R9-3-315, a predecessor to the State's current smelter rules codified at Arizona Administrative Code (AAC) R18-2-715. See 48 FR 1717 (January 14, 1983). This rule limited stack emissions from primary copper smelters, including the smelter in the Miami area. We concluded, however, that the control strategy for SO2in Arizona's six SO2nonattainment areas was incomplete due to the failure to address fugitive emissions problems. See 48 FR 1717 (January 14, 1983) and 40 CFR 52.125(a)(1).

In 1998, 2003, and 2006, the State submitted amended rules (AAC R18-2-715 (sections F, G, and H), R18-2-715.01, R18-2-715.02, and R18-2-Appendix 8).5 These rules address both fugitive and stack emissions from smelters and, in approving the rules, we found that the amended rules met the RACT requirement under CAA sections 172(c)(1) and 191(b). See 69 FR 26789 at 26788 (May 14, 2004), 69 FR 63321 (November 2, 2004), and 71 FR 18624 at 18625 (April 12, 2006). Furthermore, because the area has attained the standard, no further demonstration that RACM has been implemented need be submitted by the State.

5

A more extensive summary of the regulatory history of copper smelters in Arizona is included in EPA's proposed action on these rules. See 69 FR 26786 (May 14, 2004).

Emissions inventory.The emissions inventory requirement of section 172(c)(3) is satisfied by the maintenance plan inventory requirements. The maintenance plan inventory is evaluated below, in section IV.E.1.

NSR permit program.Section 172(c)(5) requires new source review (NSR) permits for the construction and operation of new and modified major stationary sources located in nonattainment areas. ADEQ is the agency responsible for implementing the nonattainment area NSR permit program in the Miami area. Under ADEQ's rules, all new major sources and modifications to existing major sources are subject to the NSR requirements of these rules.

We have not yet fully approved the ADEQ NSR rules.6 We have, however, determined that an area being redesignated from nonattainment to attainment does not need to have an approved NSR program prior to redesignation, provided that the area demonstrates maintenance of the standard without nonattainment NSR in effect. See memorandum from Mary Nichols dated October 14, 1994 (“Part D New Source Review (part D NSR) Requirements for Areas Requesting Redesignation to Attainment.”) We have determined that the maintenance demonstration for Miami does not rely on nonattainment NSR.

6

ADEQ's NSR rules are included in the preconstruction review and permitting provisions of Arizona Administrative Code (AAC), Title 18, Chapter 2, Articles 3 and 4. EPA approved an earlier version of ADEQ's NSR requirements (AAC R9-3-302) on May 5, 1982 (47 FR 19328) and August 10, 1988 (53 FR 30220).

Prevention of significant deterioration (PSD) is the permitting program that applies in attainment areas. PSD was established to preserve air quality in areas that are meeting the NAAQS. The PSD program requires new, modified, or reconstructed stationary sources to undergo preconstruction review and to apply best available control technology. In addition, sources are required to review PSD increment consumption and undertake preconstruction modeling. ADEQ has an EPA-approved PSD permitting program (Arizona Air Pollution Rule R9-3-304) for all criteria pollutants except respirable particulate matter (PM10). See 48 FR 19878 (May 3, 1983). The federal PSD program for PM10was delegated to the State on March 12, 1999. ADEQ's partially approved, partially delegated PSD program will apply automatically to new major sources or major modifications to existing sources of SO2in the Miami area once the area is redesignated to attainment.

Compliance with section 110(a)(2).Under section 172(c)(7), plan provisions submitted to satisfy part D must meet the applicable provisions of section 110(a)(2) of the CAA. As noted in section IV.B. above, the Miami portion of the Arizona SIP meets these requirements.

Equivalent techniques.Under section 172(c)(8), EPA may allow the use of equivalent modeling, emission inventory, and planning procedures, unless EPA determines that the proposed techniques are, in the aggregate, less effective than the methods specified by EPA. The Miami SO2Maintenance Plan relies on an equivalent modeling technique referred to as Multipoint Rollback (MPR). MPR was used to derive emissions limits for the Miami smelter that provide for attainment and maintenance of the SO2NAAQS. The State's rules containing MPR-derived emission limits for the Miami smelter were approved by EPA on January 14, 1983 (48 FR 1717) and amended versions of the rules were approved by EPA on November 1, 2004 (69 FR 63321).

b. Section 176

Section 176(c) of the CAA requires states to establish criteria and procedures to ensure that federally supported or funded projects conform to the air quality planning goals in the applicable SIP. The requirement to determine conformity applies to transportation plans, programs, and projects developed, funded or approvedunder title 23 U.S.C. or the Federal Transit Laws (“transportation conformity”) as well as to all other federally supported or funded projects (“general conformity”). Because EPA does not consider SO2a transportation-related pollutant, only the requirements related to general conformity apply to the Miami SO2area. The State of Arizona adopted general conformity criteria and procedures as a revision to the Arizona SIP. EPA approved Arizona's general conformity SIP on April 23, 1999 (64 FR 19916). Thus, the requirements of CAA section 176 have been satisfied.

c. Subpart 5

Subpart 5 of part D contains additional provisions for areas designated nonattainment for SO2. Under CAA section 191(b), States with existing nonattainment areas for the primary SO2NAAQS where those areas lack fully approved SIPs, including part D plans, must submit implementation plans meeting the requirements of subpart 1 of part D. As discussed in section IV.D.2.a of this notice, the State of Arizona has met the requirements of subpart 1 of part D for the Miami area. Under CAA section 192(b), such areas were required to meet the primary SO2NAAQS as expeditiously as possibly but no later than November 15, 1995. As discussed in section IV.A of this notice, the Miami SO2nonattainment area met the primary SO2standards well before the applicable attainment date of November 15, 1995 and has continued to attain since then.

E. The Area Must Have a Fully Approved Maintenance Plan

Section 107(d)(3)(E)(iv) of the Act makes EPA approval of a maintenance plan meeting the requirements of section 175A another prerequisite to redesignation. Under section 175A, a maintenance plan must provide for maintenance of the NAAQS for at least 10 years after redesignation, and include any additional control measures as may be necessary to ensure such maintenance. In addition, maintenance plans are to contain such contingency provisions as EPA deems necessary to assure the prompt correction of a violation of the NAAQS that occurs after redesignation. The contingency measures must include, at a minimum, a requirement that the state will implement all control measures contained in the nonattainment SIP prior to redesignation.

The Calcagni Memo contains EPA guidance on the contents of maintenance plans submitted for the purposes of meeting section 175A. Generally, such plans should address the following five topics: the attainment emissions inventory, maintenance demonstration, monitoring network, verification of continued attainment, and a contingency plan.

Lastly, under CAA section 175A(b), states are required to submit a subsequent maintenance plan eight years after redesignation providing for maintenance of the NAAQS for an additional 10-year period beyond the initial 10-year maintenance period.

1. Attainment Inventory

The Miami SO2Maintenance Plan includes an emissions inventory for point sources, area sources, and mobile sources for 1999 and 2000 as well as a projection of emissions to 2015. See table 4 below. As discussed in section IV.A of this notice, the Miami area has continued to attain the SO2NAAQS since at least 1990 and thus 1999 and 2000 are acceptable as the basis upon which to develop an “attainment emissions inventory” for the purposes of a maintenance plan.

ADEQ developed the area and mobile source estimates shown in table 4 based on EPA's AIRData for Gila County. Point source estimates are based on ADEQ annual emissions inventory data. See section 4.0 and appendix B of the Miami SO2Maintenance Plan. Sulfur dioxide emissions from the Phelps-Dodge smelter copper smelter itself are based on continuous emission monitoring systems and the assumption that stack emissions represent 25 percent of the facility's total annual (i.e., stack plus fugitive) SO2emissions. The actual percentage of total facility emissions emanating from the stacks varies from year to year (e.g., from 19 percent to 33 percent over the 1996 to 2000 period) but the 25 percent assumption is a reasonable average annual value based on material balance calculation methods.

Table 4.—SO2Emissions Inventories for 1999, 2000, and Projected Inventory for 2015 for the Miami Area (in TPY) Source type 1999 2000 2015 Area and Mobile 149 150 162 Point (excluding Miami smelter) 7 4 9 Miami Smelter 7,819 6,810 8,000 Total 7,975 6,964 8,171 Source: Miami SO2Maintenance Plan, tables 4.4 and 4.6.

Based on our review of the submitted plan, we conclude that the emissions inventory is based on reasonable methods and assumptions and is comprehensive and accurate.

2. Maintenance Demonstration

EPA allows states to demonstrate maintenance of the NAAQS by either showing that future emissions of a pollutant or its 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.7 In the case of the Miami nonattainment area, the demonstration of maintenance relies on both a projected emissions inventory for future years of 2005, 2010, and 2015 for sources in the Miami nonattainment area as well as SO2emission limits for the Miami smelter that were developed using a variant of Multipoint Rollback (MPR) modeling and intended to minimize the probability of an exceedance of the SO2NAAQS due to smelter emissions.

7

See Calcagni Memo, at p. 9.

The inventory from the Miami SO2Maintenance Plan shows that about 98% of the total SO2emissions in the Miami nonattainment area are generated by the smelter.8 Projections for the Miami smelter itself anticipate a minor increase from those in 1999 [7,819 tons per year (tpy)] to 2005 and beyond (8,000 tpy). The remaining point sources in the nonattainment area have existing permits that limit their allowable emissions to less than 100 tpy. Projections for area and mobile sources(increasing from 149 tpy9 to 162 tpy) are based on anticipated moderate increases in population and the assumption that SO2emissions from such sources are proportionate to the population. Total projected actual emissions of point, area, and mobile sources are expected to remain relatively constant, with total SO2emissions projected to be less than 24 tons on a daily basis and approximately 8,200 tons on annual basis by 2015.10 This represents an increase of only about 2 percent from 1999 levels. Thus, throughout the maintenance period, the Miami smelter is expected to continue to be the overwhelming source of SO2emissions in the area.

8See appendix B of submitted plan.

9The most recent quality assured inventory is from 1996. The 1999 SO2inventory for area and mobile sources is based on economic growth activity.

10

See table 4.6 of submitted plan.

The emissions projections for the smelter (from 7,819 tpy) in 1999 to 8,000 tpy in 2005 and beyond are based on the expectation that, through 2015, the copper industry will not expand. While the expectation of continued low price pressures on copper may well have been reasonable in 2002 when the maintenance plan was adopted, changes in the copper market in fact have occurred over the past several years raising the price for copper thereby leading to a reasonable expectation of higher production levels at the Miami smelter than anticipated in the Miami SO2Maintenance Plan.

Nonetheless, the demonstration of maintenance of the SO2NAAQS in the Miami area does not rely solely on the emissions projections, but also on the SO2emission limits established under SIP rule AAC R18-2-715 (approved by EPA in 2004 and, as amended, in 2006) and incorporated into the title V operating permit for the Phelps-Dodge Miami smelter. These limits cap stack emissions at 604 pounds per hour (lbs/hr) on an annual average basis and total facility (i.e., stacks plus fugitives) emissions at 2,420 lbs/hr on an annual basis. SIP rule AAC R18-2-715 also establishes a cumulative occurrence table that caps the number of occurrences of 3-hour average emissions above various levels with, for example, only two occurrences allowed per year of stack SO2emissions greater than 5,900 lbs/hr, 3-hour average. The total facility emissions cap (2,420 lbs/hr) corresponds to approximately 10,600 tpy assuming round-the-clock, year-round operation (the permit however cites 10,400 tpy based on 357 work days in a given year).

As explained below, ADEQ has demonstrated that the new limits are protective of the SO2NAAQS. In order to increase the smelter's emissions limits the State would have to submit a SIP revision that demonstrates that, consistent with CAA section 110(l), the revision does not interfere with maintenance of the SO2NAAQS. Therefore, the emission limits for the smelter, supported by the emissions inventory projections that show that the smelter will remain the overwhelming source of SO2emissions in the area for the foreseeable future, in essence provide the demonstration necessary to show that the Miami area will continue to attain the SO2standard indefinitely, and thereby comply with CAA section 175A(a), which requires maintenance plans to provide for maintenance of the NAAQS for at least 10 years after redesignation.

Given the link then between the SO2emission limits on the Phelps-Dodge Miami smelter and the demonstration of maintenance, the Miami SO2Maintenance Plan provides a detailed explanation of how the limits were derived and how they minimize the probability of exceedance of the SO2NAAQS due to smelter operations. See chapter 5 of the submitted plan. First, it is important to note that ADEQ used a variant of the Multipoint Rollback (MPR) method to derive these emissions limits. In brief, MPR uses the ratio of monitored concentrations to the NAAQS to determine how much to scale the smelter's existing hourly distribution of emission rates so that they meet the NAAQS. Unlike simple rollback, which yields a single maximum emission rate never to be exceeded, MPR yields limitations on the number of times per year that the facility may exceed each of a series of emission rates. In the resulting cumulative occurrence table, the larger the emissions rate, the fewer number of occurrences are allowed per year. The emission rates are chosen so that the full hourly distribution results in attainment of the NAAQS on a probabilistic basis. This approach has been approved by EPA for use with smelters because of their highly variable emission rates.11 ADEQ used a variant of MPR, as explained further below, to show that the new limits are protective of the NAAQS.

11See EPA Final Rule, “Approval and Promulgation of Implementation Plans; Arizona Plan Revision: Sulf