1 ------------------ ------------------ ----------------- ------------------ ----------------- --------------- --------------

Technical Support Document

ARIZONA Nonattainment Area Designations for the 2010 Sulfur Dioxide (SO 2 ) Primary National Ambien t Air Quality Standard

Summary

Pursuant to section 107(d) of the Clean Air Act (C AA), EPA must initially de signate areas as either “nonattainment,” “attainment,” or “unclassifiable” for the 2010 1-hour sulfur dioxide (SO 2 ) primary national ambient air qua lity standard (NAAQS). The CAA defines a nonattainment area as one that does not meet the NAAQS or that cont ributes to poor air qua lity in a nearby area that does not meet the NAAQS.

Table 1 below identifies the count ies and portions of counties in Arizona that EPA has initially designated “nonattainment” base d on monitored violations. EPA is not yet prepared to designate other areas in Arizona, and will addr ess such areas in a subsequent round of final designations.

Table 1. Nonattainment Designations for Arizona

Area (listed alphabetically) Arizona’s Recommendation of
Areas/Counties EPA’s Designated
Nonattainment
Areas/Counties Hayden Gila County (partial) Pinal County (partial) Nonattainment
Nonattainment Nonattainment
Nonattainment
Miami Gila County (partial) Nonattainment Nonattainment

Background

On June 2, 2010, EPA revised the primary SO 2 NAAQS (75 FR 35520, June 22, 2010) by establishing
a new 1-hour standard at a level of 75 parts per billion ( ppb), which is met at an ambient air quality monitoring site when the 3-y ear average of the annual 99 th percentile of the daily maximum 1-hour average concentrations is less than or equal to 75 ppb, as determined in accordance with Appendix T of 40 CFR part 50. 40 CFR 50.17(a)-(b). EPA has determined that this is the level necessary to provide protection of public health with an adequate margin of safety, especially for children, the elderly, and those with asthma. These groups ar e particularly susceptible to the health effects associated with breathing SO 2 . The Agency is revoking the two prior primary standards of 140 ppb evaluated over 24- hours and 30 ppb evaluated over an entire year b ecause the standards will not add additional public health protection given a 1-hour st andard at 75 ppb. Accordingly, EPA has not designated areas in this process on the basis of either of these two prior primary standards. Similarly, the secondary standard
for SO 2 has not been revised, so EPA has not designate d areas in this process on the basis of the secondary standard.2 EPA’s SO 2 Designation Approach

Section 107(d) of the CAA provides th at not later than 1 year after promulgation of a new or revised NAAQS, state Governors may submit their recomme ndations for designations and boundaries to EPA. This deadline was June 3, 2011. Section 107(d) also re quires EPA to provide a not ification to states of no less than 120 days prior to promul gating an initial area designation th at is a modification of a state’s
recommendation. EPA has reviewed the state’s recommendations and has notified the Governor through a letter signed by the Regi onal Administrator of any intende d modifications. While language in section 107 specifically addresses states, we intend to follow the same process for tribes, pursuant to section 301(d) of the CAA and Tribal Authority Ru le (40 CFR Part 49). Therefore, we intend to designate tribal areas, in consulta tion with the tribes, on the same sc hedule as state designations. If a state or tribe did not submit designation recommendatio ns, EPA will promulgate the designations that it deems appropriate. If a state or tribe disagree s with EPA’s intended area designations, it has an opportunity to demonstrate why any propos ed modification is inappropriate.

Designations guidance was issued by EPA thr ough a March 24, 2011, memorandu m from Stephen D. Page, Director, U.S. EPA, Office of Air Quality Planning and Standa rds, to Air Division Directors, U.S. EPA Regions I-X. This memorandum identif ies factors EPA we are using to evaluate in determining boundaries for areas designated nonattainme nt. These 5 factors in clude: 1) air quality data; 2) emissions and emissions-related data (locati on of sources and potentia l contribution to ambient
SO 2 concentrations); 3) meteor ology (weather/transport patterns) ; 4) geography/topography (mountain ranges or other air basin boundaries); and 5) jurisdictional boundaries (e .g., counties, air districts, preexisting nonattainment areas, reservations, metro politan planning organization), among any other information deemed relevant to establishing a ppropriate area designations and boundaries for the 1-
hour SO 2 NAAQS.

As defined at 18 U.S.C. 1151, “Indian country” refers to: “(a) all land within the limits of any Indian reservation under the jurisdiction of the United States Government, not withstanding the issuance of any patent, and, including rights-of -way running through the reservat ion, (b) all dependent Indian
communities within the borders of the United States whether within the original or subsequently acquired territory thereof, and whet her within or without the limits of a state, and (c) all Indian allotments, the Indian titles to which have not been extinguishe d, including rights-of-way running through the same.” EPA recognizes the sovereignty of tribal governments, and has attempted to take
the desires of the tribes into account in esta blishing appropriate nonatt ainment area designation boundaries, in accordance with EPA’s December, 2011 Policy for Establishing Separate Air Quality Designations for Areas of Indian Country 1

.

The March 24, 2011 designation memo recommended that area boundaries default to the county boundary unless additional provided information justif ies a larger or smaller boundary than the county. EPA believes it is appropriate to evaluate each potent ial area on a case-by-case basis, and to recognize that area-specific analyses conduc ted by states, tribes and/or EP A may support a different boundary than a default county boundary.

1 http://www.epa.gov/ttn/caaa/t1/memoranda/20120117indiancountry.pdf3 In this TSD, EPA discusses its review and technical analysis of the nonattainment area recommendations submitted by the state of Arizona for designations of the 1-hour SO 2 standard. Based on our review of information discussed below, EPA agrees with the state’s recommendation to designate portions of Gila Count y and Pinal County nonattainment a nd has initially designated those areas accordingly. The EPA is not yet reaching conc lusions concerning areas in Arizona, and their sources, that are outside of the nonattainment area de signations addressed in this TSD. EPA will make final initial designations decisi ons for the remaining portions of Arizona in the future.

Definition of important term s used in this document:

1) Designated nonattainment area – an area which EPA has determined, based on a state
recommendation and/or on the techni cal analysis included in this doc ument, has violated the 2010 SO 2 NAAQS, based on the most recent three years of ai r quality monitoring data , or contributes to a violation in a nearby area.

2) Recommended nonattainment area – an area that a state or tribal government has recommended to EPA to be designated as nonattainment.

3) Violating monitor – an ambient air monitor meeting all methods, quality assurance and citing criteria and requirements whose valid design valu e exceeds 75 ppb, as described in Appendix T of 40 CFR part 50.

4) 2010 SO 2 NAAQS - 75 ppb, national ambient air quality standard for SO 2 promulgated in 2010. Based on the 3-year average of the 99 th percentile of the annual dist ribution of daily maximum 1-hour average concentrations.

5) Design Value – a statistic that describes the air quality st atus of a given area rela tive to the level of the NAAQS.4 Nonattainment Designations

Technical Analysis for Hayden, Arizona

Introduction

This technical analysis for Hayden, Arizona identifies the partial county with a monitor that violates the
2010 SO 2 NAAQS, and evaluates that county and nearby counties for contributions to SO 2 concentrations in the area. EPA has evaluated th is county and nearby counties based on the weight-ofevidence of the factors in EPA’s Desi gnation Guidance, issued on March 24, 2011. 2

Figure 1 shows the Hayden area in Arizona which EP A has initially designated nonattainment. Figure 2 is a map showing the locations of SO 2 monitors in Hayden, Arizona and surrounding counties. Violating monitors are shown with a red icon; monitors attaining th e standard are shown with green icons. Design values for each monitor are listed in Figure 2, and in Table 2 below.

2 http://www.epa.gov/air/sulfurdioxide/guidance.html Figure 15 In May 2011, Governor Janice K. Brewer recommende d that portions of Gila County and Pinal County be designated as “nonattainment” and the remain ing counties and partial counties be designated
“unclassifiable” for the 2010 SO 2 NAAQS based on monitored air qua lity data from 2007-2009 (letter to EPA Region 9 Administrator Jared Blumenfeld from Governor Janice K. Brewer, May 25, 2011). Consistent with the existing Ha yden nonattainment area and Miami maintenance area for the 1971 SO 2 NAAQS, the state recommended that the same portions of Gila County and Pinal County (except those portions in Indian country) be de signated as the Hayden and Miam i nonattainment areas for the 2010
SO 2 NAAQS. The state recommendation was based prim arily on monitoring data and consideration of
emissions data from the 2005 Nationa l Emissions Inventory (NEI).

In February 2013, EPA responded to Governor Brew er’s 2011 recommendati on (“120-day” letter to
Governor Janice K. Brewer from EPA Region 9 Administrator Jared Blumenfeld, February 6, 2013). The February 2013 letter notified th e Governor of EPA’s intentions regarding designations for the 2010
SO 2 NAAQS. As stated in the lett er, EPA intended to agree with th e Governor’s recommendations for
boundaries of the two nonattainment areas the Gove rnor recommended as nonattainment. The Governor replied to EPA’s 120-day letter in April 2013 (letter to EPA Region 9 Administrator Jared Blumenfeld Figure 26 from Governor Janice K. Brewer, April 2, 2013). In the reply letter, the Governor reaffirmed the 2011 recommendations for all areas of the state, but note d that there was a discrepancy with the maps the state provided in 2011 for the Hayden, Arizona area. The 2011 maps were included in a document titled “Arizona Air Quality Designations, Final Propos ed Boundary Recommendation for the 2010 Primary National Ambient Air Quality Standard for Sulfur Dioxide” (state technical support document or state TSD).

The state TSD was attached to a letter from the state’s environmental agency to the Governor (letter to Governor Janice K. Brewer from Henry R. Darwi n, Director, Arizona Depart ment of Environmental Quality, letter dated May 2, 2011). In her April 2013 letter, Governor Brewer indicated that EPA would receive a corrected map. EPA received the co rrected map in a letter dated April 5, 2013 (letter to EPA Region 9 Administrator Jared Blumenfeld from Eric Massey, Director, Air Quality Division, Arizona Department of E nvironmental Quality).

Based on EPA's technical analysis described below, EPA concurs with the st ate’s recommendation to initially designate a portion of Gila County and a portion of Pinal County as nonattainment for the 2010
SO 2 NAAQS, as the Hayden nonattainment area. Thes e counties are listed above in Table 1. We note here that the state’s corrected map agrees with the maps that are contained in this document.

Detailed Assessment

Air Quality Data

This factor considers the SO 2 air quality monitoring data, in cluding the design values (in ppb) calculated for all air quality monitors in Gila County in the Hayden nonattainment area and in the surrounding area based on data for the 2009-2011 period.

The Governor’s recommendation was based on 2007- 2009 data from Federal Reference Method (FRM) or Federal Equivalent Method (FEM) monitors provided in the state le tter to EPA Region 9
Administrator Jared Blumen feld from Governor Janice K. Brewer, May 25, 2011. 3

The 2011 SO 2 NAAQS design values for counties in the Ha yden nonattainment area and surrounding area are shown in Table 2. Design values are calc ulated using the 3-year average of the annual 99 th percentile of 1-hour daily maximum SO 2 concentrations, and compared to the NAAQS of 75 ppb, according to requirements of 40 CFR 50.17.

3 Note: Monitors that are eligible for providing design value data generally include State and Local Air Monitoring Stations (SLAMS) that are sited in accordance with 40 CFR part 58, Appendix D (Section 4.4) and operating with a FRM or FEM monitor that meets the requirements of 40 CFR part 58, Appe ndix A. All data from a special purpose monitor (SPM) using an FRM or FEM which has operated for more than 24 mont hs are eligible for comparison to the NAAQS unless the monitoring agency demonstrates that the data came from a particular period during which the requirements of Appendix A (quality assurance requirements) or Appendix E (probe and monitoring path siting criteria) were not met.7 Table 2. Air Quality Data for Nona ttainment Designations in Arizona

County State
Recommended
Nonattainment? Monitor Name Monitor Air Quality System ID Monitor Location SO 2 Design Value,
2009-2011 (ppb)

Gila,
Arizona Yes (partial) Miami Ridgeline 04-007-0009 4030 Linden Street 111

Hayden Old Jail 04-007-1001 Jail-Canyon Dr, Hayden 259

Maricopa,
Arizona No Central Phoenix 04-013-3002 1645 E. Roosevelt St, Central
Phoenix 9

South Scottsdale 04-013-3003 2857 N. Miller Road, South
Scottsdale 8*

Durango Complex 04-013-9812 2702 AC Ester Brook Blvd 8**

JLG Supersite 04-013-9997 4530 N. 17th Ave 7*

Pima,
Arizona No 22nd and Craycroft 04-019-1011 1237 S. Beverly, Tucson 8*
Children’s Park
NCore 04-019-1028 400 W. River Road 4**
Monitors in Bold have the highest 2009-2011 design value in the respective county. Pinal County, Arizona did not have any
SO 2 monitors collecting data from 2009-2011. *Incomplete data, provided for informational purposes only, not relevant for comparison to the NAAQS. These stations stopped monitoring for comparison to the SO 2 NAAQS after December 2010. The South Scottsdale monitor was moved to the Durango Complex station; JLG Supersite started monitoring for trace levels of SO 2 instead of for comparison to the NAAQS; 22 nd and Craycroft SO 2 monitoring was moved to the Children’s Park NCore station. **Incomplete data, provided for informational purposes only, not relevant for comparison to the NAAQS. These stations began monitoring for comparison to the SO 2 NAAQS in late 2010 or 2011.

Gila County shows monitored violations of the 2010 SO 2 NAAQS. No other SO 2 monitors in Arizona
show violations of the 2010 SO 2 NAAQS. Therefore, as an analytical starting point, some areas in Gila County and possibly additional areas in surrounding counties must be designated nonattainment. Note that the absence of a violating m onitor alone is not a sufficient reas on to eliminate nearby counties as
candidates for nonattainment status. This is becaus e the Clean Air Act defines a nonattainment area as any area that violates a NAAQS or contributes to a nearby violation. 4 Each area has been evaluated based on the weight-of-evidence of the five factors and other relevant information.

Two SO 2 monitors are violating the standard in Arizona. Both viol ating monitors are located in Gila County (see Figure 2 and Table 2, above). The Hayde n Old Jail monitor (Air Quality System (AQS) ID 04-007-1001) is a source-oriented monitor located approximately 920 meters (0.57 miles) from the ASARCO, LLC – Hayden smelter stack (see Figure 2). Nestled in the southern, V-shaped tip of Gila County, the monitor is about 860 mete rs (0.54 miles) from the Pinal C ounty border (see Figure 2). The Miami Ridgeline monitor (AQS ID 04-007-0009) is also a source-oriented monitor, located approximately 1,390 meters (0.86 miles) from the Freeport-McMoRan Miami Smelter. The FreeportMcMoRan Miami Smelter is roughly 45.5 kilometers (28 miles) northwest of the ASARCO, LLC – Hayden smelter.

4 Section 107(d)(1)(A)(i) of the Clean Air Act defines a nonattain ment area as " ... any area that does not meet (or that contributes to ambient air quality in a nearby area that does not meet) the national primary or secondary ambient air quality standard for the pollutant... "8 Six additional SO 2 monitors have been operated in recent ye ars in Maricopa and Pima counties. These
monitors are not source-oriented and are located in the urban cores of the Phoenix and Tucson metropolitan areas, which are over 50 miles away from the violating monitors located in Gila County (see Figure 2, above). The low conc entrations recorded in these loca tions suggest that their design values are not impacted by the same sources that are impacting the violating monitors

.

Emissions and Emissions-Related Data

Evidence of SO 2 emissions sources in the vicinity of a vi olating monitor is an important factor for determining whether a nearby area is contributing to a monitored violation. For this factor, EPA evaluated county-level emission data for SO 2 , as well as emissions fr om nearby point sources.

Emissions

For this analysis, EPA relied on information fr om the 2008 National Emissions Inventory (NEI) emissions database (NEI08V3). Arizona did not provide updated emissions information.

Table 3 shows total emissions of SO 2 in 2008 (given in tons) for all 15 counties in Arizona and single sources emitting greater than 100 tons per year of SO 2 according to the 2008 NEI. The counties that contain part of the Hayden nonattainment area for the 2010 SO 2 NAAQS are shown in bold

. Figure 39 Table 3. SO 2 Emissions in 2008

County Facility
Located in
State
Recommended
Nonattainment
Area? Facility > 100 tons per year of SO 2 emissions Facility
Location SO 2 Air
Emissions

(2008 NEIV3)

(tons) Total County
2008 SO 2 Emissions

(tons)

Gila Yes (Hayden) ASARCO, LLC - Hayden Smelter Hayden 21,742

29,176 Yes (Miami) Freeport-McMoRan Miami Smelter Miami 7,091
- Other point, nonpoint, nonroad, onroad - 343

Apache No Salt River Project (Coronado) St. Johns 15,900

22,583 No Tucson Electric Power Co mpany Springerville 6,562

- Other point, nonpoint, nonroad, onroad - 122

Navajo No Arizona Public Service (Cholla) Joseph City 16,421

19,163 No Catalyst Paper (Snowflake) Inc. Snowflake 2,556

- Other point, nonpoint, nonroad, onroad - 186

Pima No Tucson Electric Power (Irvington) Tucson 2,884

4,718 - Other point, nonpoint, nonroad, onroad - 1,834

Maricopa No Phoenix Sky Harbor International Airport Phoenix 252

1,641 - Other point, nonpoint, nonroad, onroad - 1,389

Cochise No AZ Electric Power (Apache) Cochise 1,903

3,081 No Chemical Lime Company - Douglas Douglas 1,013

- Other sources (nonpoint, nonroad, onroad) - 165

Yavapai No Nelson Lime Plant Peach Springs 1,955

2,330 - Other point, nonpoint, nonroad, onroad - 375

Pinal - Other point, nonpoint, nonroad, onroad - 381 381

Mohave - Other point, nonpoint, nonroad, onroad 345 345

Coconino - Other point, nonpoint, nonroad, onroad - 786 786

Yuma - Other point, nonpoint, nonroad, onroad 215 215

La Paz - Other point, nonpoint, nonroad, onroad 41 41
Santa Cruz - Other point, nonpoint, nonroad, onroad 105 105

Greenlee - Other point, nonpoint, nonroad, onroad 212 212

Graham - Other point, nonpoint, nonroad, onroad - 48 48

Total emissions of SO 2 are highest in Gila County. In 2008, the ASARCO, LLC – Hayden Smelter emitted over 20,000 tons of SO 2 , three times more than the sec ond largest source (Freeport-McMoRan Miami Smelter) of SO 2 emissions in Gila County. Both smelters in Gila County are primary copper smelters. Apache and Navajo counties also contain co al-fired electric utility generating units that are large sources of SO 2 : Coronado Generating Station (15,900 tons in 2008) and Springerville Generating Station (6,562 tons in 2008) in Apache County, and Cholla Powe r Plant (16,421 tons in 2008) in Navajo County. Total emissions of SO 2 from Pinal County are low (381 tons in 2008) compared to Gila, Apache, and Navajo counties. Gila, Apache, and Navajo counties together comprise 84% of total
SO 2 emissions from the state of Arizona. These five largest stationary sources in the three counties comprised 80% of total SO 2 emissions from state lands in Ar izona in 2008. See Figure 4 for the geographic distribution of these st ationary sources. One additional source emitted over 100 tons per10 year - the Navajo Generating Statio n (3,816 tons in 2008) located on tribal lands near the city of Page in northern Coconino County, Arizona. The Navajo Generating Station is approximately 240 miles north of Freeport-McMoRan Miami Smelter and 270 miles north of the ASARCO LLC – Hayden
Smelter.

The state-recommended Hayden nonattainment area for the 2010 SO 2 NAAQS includes the ASARCO, LLC – Hayden Smelter. As shown in Figure 4 and Table 3, besides the two largest sources in Gila County, both of which EPA is including in nonattainme nt areas, there are no other facilities emitting greater than 100 tons per year of SO 2 in Gila, Pinal, or Graham County. The San Carlos tribal lands to
the east of the state’s recommende d Hayden nonattainment area also do not have any facilities emitting greater than 100 tons per year of SO 2 according to the 2008 NEIV3.

Emissions Controls

The emissions data used by EPA in this technical an alysis and provided in Ta ble 3 represent emissions levels taking into account any control strategies implemented on stationary sources in the Hayden, Arizona nonattainment area up to and includ ing 2008. Since 2008, the ASARCO, LLC – Hayden Figure 411 Smelter has completed two projects, one in 2010 i nvolving addition of a revert screen, and one in 2012 involving additional ventilation and a baghouse to se rvice three existing anode furnaces. Neither of these projects resulted in changes to permitted SO 2 emissions limits for the facility. See the source’s Title V federal operating permit renewal and two ADEQ permit actions/revisions that occurred since 2008 (52397-MPR and 54251-MPR). 5

Population

Gila County’s population as of the 2010 census was 53,597. From 2000 to 2010 the county grew by 4.4% and had a population density of 11.3 persons per s quare mile. Pinal County’ s population as of the 2010 census was 375,770. From 2000 to 2010 the county grew by 109.1% and had a population density of 70.0 persons per square mile.

Meteorology (weather /transport patterns)

Evidence of source-receptor relationships be tween specific emissions sources and high SO 2 values at violating monitors is another impor tant factor in determining the a ppropriate contributing areas and the appropriate extent of the nonattain ment area boundary. For this factor, EPA considered meteorological
data available for the area. Such data may provide evidence of the potential for SO 2 emissions sources located upwind of a violating mon itor to contribute to ambient SO 2 levels at the violation location.

Temperature and precipitation data is available from the nearby Winke lman 6 S station, part of the National Weather Service Cooperative Observer Progr am. This station typi cally measures only 14 inches of rain each year, with near ly half of that occurring during th e summer months of July through September, coinciding with the Arizona “monsoon” seas on. There is less than an inch of snow each year. Daily temperature highs range from 64 to 91 degrees Fahrenheit depending on season, and lows range from 31 to 69 degrees Fahrenheit. S ee Figure 5 for the location of the Winkleman meteorological station.

The varied elevations in the area cause complex wi nd flow locally. Within and adjacent to the Gila River and San Pedro River valleys, drainage winds tend to dominate at night under stable conditions. To the west of the smelter, draina ge flows toward the west, while east of the smelter the drainage flows
to the south. Given the smelter's elevated lo cation and plume buoyancy, some emissions would be expected to rise above these surface flows. Howe ver, on sunny days the heated ground warms the air and enhances vertical mixing. Under such convec tive conditions, the plum e could nevertheless be mixed down to the ground to varying degrees. This vertical mixing also causes the flow to be coupled with winds aloft, which generally flow toward the east.

Over the years, wind data has been collected at multiple locations in and around Hayden. Sites include the Hayden Maintenance Yard (“Hayden”), Hayd en-Winkelman High School (“Winkelman”), and Globe Highway (data prepared for “Draft Report, Remedial Investigation Report for the ASARCO, LLC Hayden Plant Site, Hayden, Gila County, Arizona”, Prepared for U.S. Environmental Protection Agency Region IX, San Francisco, CA., CH2M Hill, August 2008). These stati ons are shown in Figure 5. Wind roses from these stations are shown in Figur e 6. The Winkelman site is nearest the junction of

5 Further information about Arizona federal Title V air permits can be found on EPA’s website at: http://www.epa.gov/region9/air/permit/title-v-permits.html12 the Gila and San Pedro River valleys, and the Globe Highway site is in the northeastern portion of the Gila River valley before it joins the San Pedro. All of the dominant wind directi ons are consistent with the orientation of the valleys. However, when morning and evening wind frequencies are plotted separately, not all of the directions are consistent with slope flow, e.g., afternoon flow at Hayden is toward the east, but downslope flow in the Gila River valley would be toward the northwest. There is a similar evening component toward the east at Winkelm an on some days, but more of a downslope flow on other days. At Globe Highway, flow directions are consistent with slope flows. The differences between sites located relatively close together show th e complexity of the flow in the area. Transport of pollutants would be expected to occur mainly along the Gila-San Pedro River valleys (northwestsoutheast orientation), somewhat ci rcumscribed by the orientations of the valleys and the surrounding
mountains.

Terrain Around Hayden, Arizona: with SO 2 monitor (red circle), cities (purple circles & labels), meteorological stations (blue triangles & labels).

Figure 513 Hayden a.m. and p.m. wind roses

Winkelman a.m. and p.m. wind roses

Figure 614 Geography/topography (mountain ranges or other air basin boundaries)

As shown in Figure 5 (above) and Figure 7 (below ), Hayden and the ASARCO, LLC - Hayden smelter are located in very complex terra in, with the Gila River making a winding semi-circle around the east and south of the facility, and inte rsected by the San Pedro River valley from the south. The facility itself is elevated relative to the valleys; there is a 200-f oot hill just south of the facility. In all directions there is a mountain side. Hayden is at roughly 2,000 feet elevation; the Dripping Springs Mountains to the north rise to 4,000 feet; the To rtilla Mountains on the northwest, west, and south rise 3,300 to 4,000 feet. Terrain rises more gently within the Gila-San Pedro River valleys from the northwest toward the southeast. The nonattainment area encompasses the G ila River valley from where it narrows in the northwest corner of the area, to where it joins with the San Pedro River valley in roughly the center of the area, and to a bend in the San Pedro River in the southeast corner. The surrounding mountains likely limit the extent of the area exceeding the SO 2 standard to a relatively small area around the smelter, the main source of SO 2 emissions. In light of this, we are not yet prepared to conclude whether locations outside the particular valleys intersecti ng at Hayden contribute to the violating monitor’s design value.

Figure 715 Jurisdictional boundaries

To manage air quality, the state of Arizona ha s one state agency, the Arizona Department of Environmental Quality (ADEQ), an d three local agencies: Maricopa County Air Quality Department, Pima County Department of Environmental Quality, and Pinal County Air Qualit y Control District. Air quality planning for the existing Hayd en nonattainment area under the 1971 SO 2 NAAQS, composed of the same portions of Gila and Pi nal counties as the state’s recomm ended nonattainment area for the
2010 SO 2 NAAQS, is under the jurisdiction of ADEQ. Originally, for the 1971 NAAQS, the Hayden area was split between two county-wide SO 2 nonattainment areas for Gila and Pinal counties (see 43 FR 8968, March 3, 1978). At the request of the state of Arizona, the boundary for the Hayden area was reduced to nine townships in and around the town of Hayden (44 FR 21261, April 10, 1979). 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 Hayden SO 2 area, that continued to be designated
as nonattainment at the time of enactment of the CA AA, i.e., areas that had not been redesignated to ‘‘attainment’’ prior to the CAAA’ s November 15, 1990 enactment date. The then-existing nonattainment area for Hayden under the 1971 SO 2 NAAQS included a portion of Indian country along the eastern boundary. The Hayden nonattainment area for the 2010 SO 2 NAAQS includes the same geographic area as the existing no nattainment area for the 1971 SO 2 NAAQS without the portion of Indian country.

As defined at 18 U.S.C. 1151, “Indian country” refers to: “(a) all land within the limits of any Indian reservation under the jurisdiction of the United States Government, not withstanding the issuance of any patent, and, including rights-of -way running through the reservat ion, (b) all dependent Indian
communities within the borders of the United States whether within the original or subsequently acquired territory thereof, and whet her within or without the limits of a state, and (c) all Indian allotments, the Indian titles to which have not been extinguishe d, including rights-of-way running through the same.” EPA recognizes the sovereignty of tribal governments, and has attempted to take
the desires of the tribes into account in establ ishing appropriate nonattai nment area boundaries. No areas of Indian country are included in the in itial Hayden, Arizona nonatt ainment area. Figures depicting areas of Indian country in this documen t are intended for illustrative purposes only and are not an EPA determination of Indian country status or of any Indian country boundary.

Other Relevant Information

In its May 25, 2011 letter, ADEQ pr ovided additional information to support its assertion that presumptive use of full county boundaries as the nona ttainment area boundary is inappropriate for geographically large counties. The state argue d that the use of full county boundaries as the presumptive nonattainment area boundary for a violating monitor results in disparities in the size of nonattainment areas. For example, the state compar ed the area of Gila County (4,796 square miles) with the area of the entire state of Connecticut (4 ,845 square miles). A violating monitor in Middlesex County, Connecticut, would resu lt in a presumptive nonattainm ent area boundary encompassing 369 square miles. Applying this presumption in Ar izona would result in a nonattainment area (Gila County) that is 13 times larger than a full Middles ex County nonattainment area in Connecticut. The state further highlighted that the violating mon itor in its recommended Hayden nonattainment area is16 less than 0.5 miles from the southw est border of Gila and Pinal counties, and more than 100 miles from
the northern border of Gila and Coco nino counties. Therefore, the state concluded that its consideration of partial counties for th e Hayden and Miami nonattainment areas was appropriate.

Conclusion

After considering the factors descri bed above, EPA concurs with the st ate’s recommendation to initially designate a portion of Pinal Count y and a portion of Gila County as the Hayden, Arizona nonattainment
area for the 2010 SO 2 NAAQS, based on the violating monitor in Hayden, Arizona. No areas of Indian country are included in the initial Hayden, Arizona nona ttainment area. Areas of Indian country in the state of Arizona will be further addressed in a subsequent round of final initial designations.

The air quality monitor in Hayden, Arizona shows a violation of the 2010 SO 2 NAAQS based on 2009- 2011 air quality data. EPA concludes that the st ate’s recommended boundary contains the area violating the standard as well as areas causing or contributing to the monitored violation, as assessed using our five-factor methodology. The monitor is sour ce-oriented, and is located in the southernmost tip of Gila County. Due to constraints imposed by the complex terrain in the Hayden area (see Geography/Topography discussion above), it is expected that the extent of the area exceeding the SO 2 standard is confined to a relativel y small area around the main source of SO 2 emissions, the ASARCO, LLC - Hayden smelter. In light of this, we are no t yet prepared to conclude whether locations outside the particular valleys intersecti ng at Hayden contribute to NAAQS ex ceedances recorded at the Hayden monitor. The meteorology factor is not significa nt in determining a bounda ry for the nonattainment area, but available data confir ms the importance of the topogra phy in limiting the extent of the nonattainment area to the nearby ri ver valleys and their surroundings. Based on this information, we are not yet prepared to conclude that the emi ssions from sources loca ted outside the state’s recommended boundary contribute to the monitored viol ation or to other possible violations. We will
further address such sources and their areas in a subsequent round of final initial designations. The state’s recommended boundary for the Hayden nonattainment area is also consistent with the existing Hayden nonattainment boundary for the 1971 SO 2 NAAQS, without areas ofIndian country. All nonIndian country lands in the nonattainmen t area are under the jurisdiction of ADEQ.

Based on the consideration of all the relevant an d available information, as described above, EPA’s
conclusion is that the boundaries described herein encompass an area that does not meet (or that contributes to ambient air quality in a nearby area that does not meet) the 2010 SO 2 NAAQS, based on the violating monitor information in the Hayden, Ariz ona area. Areas and sour ces that EPA is not yet prepared to conclude are contributing to the monitore d violation or to other po ssible violations are not
included in this initial nonattainment area. In the fu ture, we will make final initial designation decisions
for areas in Arizona not include d in the nonattainment area designa tions addressed in this TSD.17 Technical Analysis for Miami, Arizona

Introduction

This technical analysis for Miami, Arizona identifies the partial county with a monitor that violates the
2010 SO 2 NAAQS and evaluates nearby c ounties for contributions to SO 2 concentrations in the area. EPA has evaluated this county and nearby counties based on the weight -of-evidence of the factors in EPA’s Designation Guidance, issued on March 24, 2011. 6

Figure 8 shows the Miami area in Arizona which EP A has initially designated nonattainment. Figure 9 is a map of SO 2 monitors in the area and the surrounding countie s. Violating monitors are shown with a red icon; monitors attaining the standard are shown with green icons . Design values for each monitor are listed in Figure 9 and in Table 4, below.

6 http://www.epa.gov/air/sulfurdioxide/guidance.html Figure 818 In May 2011, Governor Janice K. Brewer recommende d that portions of Gila County and Pinal County be designated as “nonattainment,” and the remain ing counties and partial counties be designated
“unclassifiable” for the 2010 SO 2 NAAQS based on monitored air qua lity data from 2007-2009 (letter to EPA Region 9 Administrator Jared Blumenfeld from Governor Janice K. Brewer, May 25, 2011). Consistent with the existing Ha yden nonattainment area and Miami maintenance area for the 1971 SO 2 NAAQS, the state recommended that the same portions of Gila County and Pi nal County be designated as the Hayden and Miami nonattainment areas for the 2010 SO 2 NAAQS. The state recommendation was based primarily on monitoring data and consid eration of emissions data from the 2005 National Emissions Inventory (NEI).

In February 2013, EPA responded to Governor Brew er’s 2011 recommendati on (“120-day” letter to
Governor Janice K. Brewer from EPA Region 9 Administrator Jared Blumenfeld, February 6, 2013). The February 2013 letter notified th e Governor of EPA’s intentions regarding designations for the 2010
SO 2 NAAQS. As stated in the lett er, EPA intended to agree with th e Governor’s recommendations for
boundaries of the two nonattainment areas the Gove rnor recommended as nonattainment. The Governor replied to EPA’s 120-day letter in April 2013 (letter to EPA Region 9 Administrator Jared Blumenfeld Figure 919 from Governor Janice K. Brewer, April 2, 2013). In the reply letter, the Governor reaffirmed the 2011
recommendations for all areas of the state.

Based on EPA's technical analysis described below, EPA concurs with the st ate’s recommendation to initially designate a portion of Gila County as nonattainment for the 2010 SO 2 NAAQS, as the Miami nonattainment area. The county is listed above in Table 1.

Detailed Assessment

Air Quality Data

This factor considers the SO 2 air quality monitoring data, in cluding the design values (in ppb) calculated for all air quality monitors in Gila County, in the Miami nonattainment area and the surrounding area based on data for the 2009-2011 period.

The Governor’s recommendation was based on 2007- 2009 data from Federal Reference Method (FRM) or Federal Equivalent Method (FEM) monitors provided in the state le tter to EPA Region 9
Administrator Jared Blumen feld from Governor Janice K. Brewer, May 25, 2011. 7

The 2010 SO 2 NAAQS design values for counties in the Miami nonattainment area and surrounding area are shown in Table 4. Design va lues are calculated using the 3-year average of the annual 99 th percentile of 1-hour daily maximum SO 2 concentrations, and compared to the NAAQS of 75 ppb, according to requirements of 40 CFR 50.17.

7 Note: Monitors that are eligible for providing design value data generally include State and Local Air Monitoring Stations (SLAMS) that are sited in accordance with 40 CFR Part 58, Appendix D (Section 4.4) and operating with a FRM or FEM monitor that meets the requirements of 40 CFR Part 58, Appe ndix A. All data from a special purpose monitor (SPM) using an FRM or FEM which has operated for more than 24 mont hs are eligible for comparison to the NAAQS unless the monitoring agency demonstrates that the data came from a particular period during which the requirements of Appendix A (quality assurance requirements) or Appendix E (probe and monitoring path siting criteria) were not met.20 Table 4. Air Quality Data for Nona ttainment Designations in Arizona

County State
Recommended
Nonattainment? Monitor Name Monitor Air Quality System ID Monitor Location SO 2 Design Value,
2009-2011 (ppb)

Gila,
Arizona Yes (partial) Miami Ridgeline 04-007-0009 4030 Linden Street 111

Hayden Old Jail 04-007-1001 Jail-Canyon Dr, Hayden 259

Maricopa,

Arizona No Central Phoenix 04-013-3002 1645 E. Roosevelt St,
Central Phoenix 9

South Scottsdale 04-013-3003 2857 N. Miller Road, South
Scottsdale 8* Durango Complex 04-013-9812 2702 AC Ester Brook Blvd 8**

JLG Supersite 04-013-9997 4530 N. 17th Ave 7*

Pima,
Arizona No 22nd and Craycroft 04-019-1011 1237 S. Beverly, Tucson 8*
Children’s Park
NCore 04-019-1028 400 W. River Road 4**
Monitors in Bold have the highest 2009-2011 design value in the respective county. *Incomplete data, provided for informational purposes only, not relevant for comparison to the NAAQS. These stations stopped monitoring for comparison to the SO 2 NAAQS after December 2010. The South Scottsdale monitor was moved to the Durango Complex station; JLG Supersite started monitoring for trace levels of SO 2 instead of for comparison to the NAAQS; 22 nd and Craycroft SO 2 monitoring was moved to the Children’s Park NCore station. **Incomplete data, provided for informational purposes only, not relevant for comparison to the NAAQS. These stations began monitoring for comparison to the SO 2 NAAQS in late 2010 or 2011.

Gila County shows monitored violations of the 2010 SO 2 NAAQS. No other SO 2 monitors in Arizona
show violations of the 2010 SO 2 NAAQS. Therefore, as an analytical starting point, some areas in Gila County and possibly additional areas in surrounding counties must be designated nonattainment. Note that the absence of a violating m onitor alone is not a sufficient reas on to eliminate nearby counties as
candidates for nonattainment status. This is becaus e the Clean Air Act defines a nonattainment area as any area that violates a NAAQS or contributes to a nearby violation. 8 Each area has been evaluated based on the weight-of-evidence of the five factors and other relevant information.

Two SO 2 monitors are violating the standard in Arizona. Both viol ating monitors are located in Gila County (see Table 4 and Figure 9, above). The Miami Ridgeline m onitor (AQS ID 04-007-0009) is a source-oriented monitor, located approximately 1 ,390 meters (0.86 miles) fr om the Freeport-McMoRan Miami Inc. (FMMI) copper smelter (see Figure 10). The FMMI smelter is roughly 45.5 kilometers (28 miles) northwest of the other violating monitor, Hayden Old Jail, a source-oriented monitor located near the ASARCO, LLC – Hayden smelter.

8 Section 107(d)(1)(A)(i) of the Clean Air Act defines a nonattain ment area as " ... any area that does not meet (or that contributes to ambient air quality in a nearby area that does not meet) the national primary or secondary ambient air quality standard for the pollutant... "21 Six additional SO 2 monitors have been operated in Maricopa and Pima counties in recent years. These
monitors are not source-oriented and are located in the urban cores of the Phoenix and Tucson metropolitan areas, which are over 50 miles away from the violating monitors located in Gila County (see Figure 9, above). The low recorded concentrati ons in these locations s uggest that their design values are not impacted by the same sources that are impacting the violating monitors.

Emissions and Emissions-Related Data

Evidence of SO 2 emissions sources in the vicinity of a vi olating monitor is an important factor for determining whether a nearby area is contributing to a monitored violation. For this factor, EPA evaluated county level emission data for SO 2 , as well as emissions from nearby point sources.

Emissions

For this analysis, EPA relied on information fr om the 2008 National Emissions Inventory (NEI) emissions database (NEI08V3). Arizona did not provide updated emissions information. Figure 1022 Table 5 shows total emissions of SO 2 (given in tons per year) for a ll 15 counties in Arizona and sources emitting greater than 100 tons per year of SO 2 according to the 2008 NEI. The county that contains all
of the Miami nonattainment area for the 2010 SO 2 NAAQS is shown in bold

.

Table 5. SO 2 Emissions in 2008

County Facility
Located in
State
Recommended
Nonattainment
Area? Facility > 100 tons per year of SO 2 emissions Facility
Location SO 2 Air
Emissions (2008 NEI V3) (tons) Total County
2008 SO 2 Emissions

(tons)

Gila Yes (Hayden) ASARCO, LLC - Hayden Smelter Hayden 21,742

29,176 Yes (Miami) Freeport-McMoRan Miami Smelter Miami 7,091
- Other point, nonpoint, nonroad, onroad - 343

Apache No Salt River Project (Coronado) St. Johns 15,900

22,583 No Tucson Electric Power Co mpany Springerville 6,562

- Other point, nonpoint, nonroad, onroad - 122

Navajo No Arizona Public Service (Cholla) Joseph City 16,421

19,163 No Catalyst Paper (Snowflake) Inc. Snowflake 2,556

- Other point, nonpoint, nonroad, onroad - 186

Pima No Tucson Electric Power (Irvington) Tucson 2,884

4,718 - Other point, nonpoint, nonroad, onroad - 1,834

Maricopa No Phoenix Sky Harbor International Airport Phoenix 252

1,641 - Other point, nonpoint, nonroad, onroad - 1,389

Cochise No AZ Electric Power (Apache) Cochise 1,903

3,081 No Chemical Lime Company - Douglas Douglas 1,013

- Other sources (nonpoint, nonroad, onroad) - 165

Yavapai No Nelson Lime Plant Peach Springs 1,955

2,330 - Other point, nonpoint, nonroad, onroad - 375

Pinal - Other point, nonpoint, nonroad, onroad - 381 381

Mohave - Other point, nonpoint, nonroad, onroad 345 345

Coconino - Other point, nonpoint, nonroad, onroad - 786 786

Yuma - Other point, nonpoint, nonroad, onroad 215 215

La Paz - Other point, nonpoint, nonroad, onroad 41 41
Santa Cruz - Other point, nonpoint, nonroad, onroad 105 105

Greenlee - Other point, nonpoint, nonroad, onroad 212 212

Graham - Other point, nonpoint, nonroad, onroad - 48 48

Total emissions of SO 2 are highest in Gila County. In 2008, the FMMI copper smelter was the second largest source of SO 2 emissions in Gila County, and the fourth la rgest source in Arizona. Both smelters (FMMI and ASARCO, LLC) in Gila County are primar y copper smelters. Apache and Navajo counties
also contain coal-fired elect ric utility generating units that are large sources of SO 2 : Coronado Generating Station (15,900 tons in 2008) and Springerville Generating St ation (6,562 tons in 2008) in Apache County, and Cholla Power Plant (16,421 tons in 2008) in Navajo County. Total emissions of23 SO 2 from Pinal County are low (381 tons in 2008) co mpared to Gila, Apache, and Navajo counties. Gila, Apache, and Navajo counties to gether comprise 84% of total SO 2 emissions from the state of Arizona. The five largest stati onary sources in thos e three counties comprised 80% of total SO 2 emissions from Arizona in 2008. The existing Miami maintenance area for the 1971 SO 2 NAAQS is
identical to the state’s recommended Miami nonattainment area for the 2010 SO 2 NAAQS and includes the FMMI smelter. See Figure 11.

Emissions Controls

The emissions data used by EPA in this technical an alysis and provided in Ta ble 5 represent emissions levels taking into account any c ontrol strategies implemented on st ationary sources in the Miami, Arizona nonattainment area up to and including 2008. Since 2008, FMMI has had several permit revisions, including: installa tion of a coal injection system with a dust collector system, clarification and/or correction to existing permit conditions, revisi on to allow additional use of an existing screening machine, update of the sulfur balance methodology to include a gravimetric method, and addition of small internal combustion engines. None of the permit revisions resulted in changes to permitted SO 2 emission limits. See seven ADEQ permit actions/r evisions from 2008 to the present: 43398-SPR, Figure 1124 45593-MPR, 48448-MPR, 49986-MPR, 54218-MPR, 55226-MPR, and 55691-MPR. These seven permit actions/revisions were included in the Title V Renewal Operating Permit 53592 issued November 26, 2012. 9

Population

Gila County’s population as of the 2010 census was 53,597. From 2000 to 2010 the county grew by 4.4% and had a population density of 11.3 persons per square mile.

Meteorology (weather /transport patterns)

Evidence of source-receptor relationships be tween specific emissions sources and high SO 2 values at violating monitors is another impor tant factor in determining the a ppropriate contributing areas and the appropriate extent of the nonattain ment area boundary. For this factor, EPA considered meteorological
data available for the area. The data ma y provide evidence of the potential for SO 2 emissions sources located upwind of a violating mon itor to contribute to ambient SO 2 levels at the violation location.

Temperature and precipitation data are available fr om the Miami station, part of the National Weather Service Cooperative Observer Program. Around 20 inch es of rain fall each year at the Miami station, roughly evenly distributed between the months, except in April, May, and June, when less than a half inch of rain falls per month. Normal daily temper ature highs range from 96 degrees Fahrenheit (°F) in summer to 62 °F in winter, while normal lows are 65 °F in summer to 34 °F in winter.

The closest meteorological station to the violating Miami monitor is Globe station CW1546, part of the National Weather Service Cooperative Observer Program. The city of Globe is about five miles from Miami, roughly to the east. Globe is in the Pinal Creek Valley, oriented at right angles to the valley where Miami is located, with a mo re west-east orientation. The 2010 wind data shows flows consistent with the valley orientation (see Figu re 12). Flow toward the west is the most frequent, but flow toward
the east-southeast also occurs. Some , but not all of the flows are cons istent with diurnal slope flows; the complexity of the surrounding terrain means there are multiple influences controlling the flow. Because of the complex terrain, and the spatial separati on from Miami, this data is of limited usefulness for drawing conclusions about th e Miami nonattainment area boundary, ex cept to illustra te that flows largely conform to valley orientation, with slope flow being an important phenomenon.

9 Further information about Arizona federal Title V air permits can be found on EPA’s website at: http://www.epa.gov/region9/air/permit/title-v-permits.html25 Globe CW1546 Wind Rose, 2010; A.M. hours

Globe CW1546 Wind Rose, 2010; P.M. hours Globe a.m. and p.m wind roses

Figure 1226 Geography/topography (mountain ranges or other air basin boundaries)

As shown in Figures 13 and 14, Miami and the FMMI sm elter are located in complex terrain. Miami is at roughly 3,500 feet elevation, lo cated in the southwes t-northeast tending rive r valley of the Bloody Tanks Wash. To the northeast, this valley joins the Pinal Wash at a right angle; the Wash then tends northwest and merges with the Pinal Creek Valle y. Northeast beyond this juncture, the Apache Peaks rise to 4,300 feet, and to 6,200 feet a bit outside of the nonattainment area. To the northwest, Webster Mountain rises to 5,000 feet; the Pina l and other mountain ranges to th e south and southwest rise to 6,500 feet; there are various other ri dges to the southeast. Thus, Miami is essentially surrounded by mountains in all directions; its im mediate valley makes a right-angle turn into the Pinal Creek Valley, which is all within the nonattainment area except for a short narrow portion in the north. The existing
nonattainment boundaries contain all the areas topographically connected with Miami.

Terrain Around Miami, Arizona SO 2 Nonattainment Area: with SO 2 monitor (red circle), cities (purple circles & labels), meteorological stations (blue triangles & labels).

Figure 1327 Jurisdictional boundaries

As discussed in the preceding technical analysis for the Hayden nonattainment area, for air quality management purposes, Gila County falls under the jurisdiction of ADEQ. For the 1971 SO 2 NAAQS,
the Miami SO 2 nonattainment area was not separately defi ned but rather that geographic area was included in a county-wide SO 2 nonattainment area (see 43 FR 8968, Ma rch 3, 1978). At the request of the state of Arizona, EPA reduced the area’s boundaries to include nine townships in and around the city of Miami (44 FR 21261, April 10, 1979). See also, 40 CFR section 81.303. 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 SO 2 nonattainment area, that continued to be designated as nonattainment at the time of enactme nt of the CAAA, i.e., areas that had not been redesignated to ‘‘att ainment’’ prior to the CAAA’s November 15, 1990 enactment date. The area
achieved attainment with the 1971 SO 2 NAAQS in 1984, and ADEQ submitted a maintenance plan to EPA in 2002. In January 2007, EPA redesignated the Mi ami nonattainment area to attainment (72 FR 3061, January 24, 2007). In this redesignation and main tenance plan approval, EPA also corrected the boundary of the Miami SO 2 nonattainment area to exclude a noncontiguous township that was Figure 1428 erroneously included in the descripti on of the area and to fix a transcri ption error in the listing of one of the other townships (see 72 FR 3061, January 24, 2007 and 40 CFR section 81.303). The Miami
nonattainment area for the 2010 SO 2 NAAQS has the same boundaries as the 1971 SO 2 NAAQS
maintenance area.

Other Relevant Information

In its May 25, 2011 letter, ADEQ pr ovided additional information to support its assertion that presumptive use of full county boundaries as the nona ttainment area boundary is inappropriate for geographically large counties. The state argue d that the use of full county boundaries as the presumptive nonattainment area boundary for a violating monitor results in regional disparities in the size of nonattainment areas. For example, the stat e compared the area of Gila County (4,796 square miles) with the area of the entire state of Conn ecticut (4,845 square miles). A violating monitor in Middlesex County, Connecticut, would result in a presumptiv e nonattainment area boundary encompassing 369 square miles. Applying this pres umption in Arizona would result in a nonattainment area (Gila County) that is 13 times larger than a full-county nonatta inment area in Connecticut. Therefore, the state concluded that its consider ation of partial counties for the Hayden and Miami nonattainment areas was appropriate.

Conclusion

After considering the factors descri bed above, EPA concurs with the st ate’s recommendation to initially designate a portion of Gila County li sted in Table 1 as the Miami, Arizona nonattainment area for the
2010 SO 2 NAAQS, based on the violating monitor in Miami, Arizona.

The air quality monitor in Miami, Ar izona shows a violation of the 2010 SO 2 NAAQS, based on 2009- 2011 air quality data. The Freeport-McMoRan Miami Inc. (FMMI) copper smelter located less than 1,400 meters (less than 0.86 mile) away from the violating monitor is e xpected to be the source of the emissions causing the monitored violation. Miam i is essentially surroun ded by mountains in all directions. Due to the constraints imposed by the complex terrain in the Miami area (see Geography/Topography discussion above), th e extent of the area exceeding the SO 2 standard is expected to be confined to a relative ly small area around the main source of SO 2 emissions, the FMMI copper smelter. In light of this, we are not yet prepared to conclude whet her locations outside the particular valley containing Miami contribute to the Miami monitor’s recorded exceedances. The meteorology factor did not play a si gnificant role in determining a boundary for the nonattainment area,
but available data confirms the relevance of the topography in limiting the extent of the nonattainment area to the nearby river valleys and their surroundings. The nonattainment boundaries recommended by the state are therefore expected to contain areas topographically c onnected with Miami and causing or contributing to the monitored violation. We are not yet prepared to conclude that the emissions from
sources located outside the state’ s recommended boundary contribute to the monitored violation or to other possible violations, and will further address such sources and their areas in a subsequent round of final initial designations.

Based on the consideration of all the relevant an d available information, as described above, EPA’s
conclusion is that the boundaries described herein for the Miami, Arizona nonattainment area encompass an area that does not meet (or that contri butes to ambient air quality in a nearby area that29 does not meet) the 2010 SO 2 NAAQS, based on the violating monito r information. No areas of Indian country are included in the Miami, Arizona nonattain ment area. Areas and sources that EPA is not yet prepared to conclude are contributing to the monitore d violation or to other po ssible violations are not
included in this initial nonattainment area. In the future, we will make final designation decisions for
areas in Arizona not included in the nonattainment area designations a ddressed in this TSD.