### i 

# Pinal County, Arizona

Area Redesignation for the 1987 24-hour PM10 National Ambient Air Quality Standard

Technical Support Document

9/21/2010

US Environmental Protection Agency
Region 9

### ii



## Table of Contents

**Introduction ......................................**

**................................................... ............................................. 1** 

**Factor 1: Air Quality Data ........................**

**................................................... ........................................ 5** 

**Factor 2: Emissions Data ..........................**

**................................................... ....................................... 8** 

**Factor 3: Population Density and Degree of Urbaniz ation .............................................**  **.................... 15**

**Factor 4: Traffic and Commuting Patterns .........**

**................................................... ............................ 17** 

**Factor 5: Growth Rates and Patterns ..............**

**................................................... .............................. 22** 

**Factor 6: Meteorology ............................**

**................................................... ...................................... 23** 

**Factor 7: Geography and Topography ...............**

**................................................... ............................ 25** 

**Factor 8: Jurisdictional Boundaries**

**.................................................. ................................................ 28** 

**Factor 9: Level of Control of Emissions Sources .**

**................................................... ........................... 31** 

**Conclusion........................................................................................................................... ................................31** 

**Appendix A – Emissions in Pinal County: Primary PM 10**  **, NO**

**x , NH**  **3 , SO**  **2 , VOCs ................................... A-1** 

**Appendix B – ADEQ Maps of PM 10**  **Sources .......................................... ............................................ B-1** 

### 1 

## T ECHNICAL 

## S UPPORT DOCUMENT


## P INAL 

## C OUNTY



## , A RIZONA


## A REA 

## R EDESIGNATION FOR THE 

## 1987 24- HOUR 

## PM 10 

## NAAQS

Introduction

Pursuant to section 107(d)(3) of the Clean Air Act (CAA), EPA may notify the governor of any

state that available information indicates that the designation of any area should be revised. Based on monitoring data that indicated persistent violations of the 1987 24-hour PM 10 

### national ambient air quality standard (NAAQS), EPA notified the Governor of Arizona and tribal leaders for the Ak-Chin Indian Community (Ak-Chin), the Gil a River Indian Community (GRIC), the San Carlos Apache Tribe, and the Tohono O’odham Nat ion (TON) that it was initiating the process to redesignate to nonattainment those viola ting areas within Pinal County, and any nearby areas that could be causing or contributing to those violations. EPA requested recommendations for the redesignation by February 1 1, 2010, consistent with the timelines set

out in the CAA.

Under section 107(d)(3)(A) of the CAA, EPA is direc ted by Congress to evaluate “air quality data, planning and control considerations, or any o ther air quality-related considerations the Administrator deems appropriate” in its redesignati on actions. Because our redesignation involves a nonattainment area (NAA), we are also ta king into account CAA section 107(d)(1)(A), which provides that nonattainment are as are to include the geographic area that does not meet, or that contributes to ambient air q uality in a nearby area that does not meet the NAAQS for a given pollutant.

This technical analysis for Pinal County identifies the monitors that violate the 24-hour PM 10 

### standard and evaluates surrounding areas for contri butions to particulate concentrations in the area. EPA guidance 1 

### provides for the use of “a qualitative analysis of the area of representativeness of the monitoring station, toget her with the consideration of terrain, meteorology, and sources of emissions...” in defining area boundaries.

Consistent with that guidance, EPA has evaluated th e area based on the weight of evidence of the following factors and other relevant information:

- air quality data - pollutant emissions - population density and degree of urbanization - traffic and commuting patterns - growth - meteorology - geography and topography - jurisdictional boundaries

- level of control of emissions sources

1 PM 10 SIP Development Guideline, EPA-450/2-86-001, June 1987.

### 2

We also used analytical tools and data such as wind roses, particle composition monitoring data, and the correlation between meteorological data and particle composition data to evaluate the

area.

Figure 1 is a map of the area showing relevant info rmation such as the locations of air quality monitors, boundaries for counties and Indian lands, and nearby PM 10 

### nonattainment areas.

Figure 1. Pinal County PM 10 

### Monitors and Nearby Nonattainment Areas

In response to EPA’s request for recommendations, o n February 11, 2010, the Tohono O’odham Nation submitted a recommendation for designation a s attainment/unclassifiable for TON’s lands. The Gila River Indian Community noted that c ertain exceedances have been flagged as caused by exceptional events, and declined to submi t a recommendation until formal

consultation has been conducted. GRIC reaffirmed t his request in a letter dated May 27, 2010. The Ak-Chin Tribe made a verbal request for formal consultation and later, in a letter dated September 2, 2010, submitted a recommendation that EPA designate reservation lands as “attainment/unclassifiable.” The San Carlos Apache Tribe did not submit a recommendation. Arizona’s submittal, dated March 26, 2010, recommen ded that only a portion of central-western Pinal County be redesignated as nonattainment. EPA has taken these recommendations under consideration, and while EPA agrees that a partial county redesignation is appropriate, we find Florence (Tohono O'Odham)

Village

San (Tohono O'Odham) Lucy Farm

Rillito planning

area Phoenix planning area

Miami planning

area

Hayden planning

area San
Carlos Fort

McDowell

Salt River

Gila
River

Ak-Chin

Tohono

O'Odham

Cochise County Gila County

Graham County Maricopa County

Pima County Pinal County

0 10 20 5 Miles

Violating PM-10 monitor

Attaining PM-10 monitor

Existing PM-10 nonattainment area

Tribal lands

County boundary

Sources: USEPA's Air Quality Systems (AQS) database (2010), TANA (2006). AIR1000045_1 23 August 2010

### 3

that the information provided to date does not adeq uately support the State’s recommended boundary. As discussed in more detail below EPA fi nds that the State’s recommended boundary

does not include sources of emissions that are like ly causing or contributing to violations of the

24-hour PM 10 

### standard. Accordingly, a larger portion of Pinal C ounty is included within EPA’s intended nonatttainment area boundary. See Figure 2 . EPA will consider any additional information that is provided by the State, tribal l eaders, and the public in making its final decision on the designation.

As shown in Figure 2, EPA is proposing that the mai n reservation of the TON, which lies to the south and west of EPA’s proposed NAA remain “unclas sifiable.” EPA believes that the primary contributors to nonattainment in Pinal County, e.g. , onroad emissions, agriculture, stationary industrial sources, and concentrated animal feedlot operations either are not present on the TON’s main reservation, or are present in relativel y small amounts, and population density is very low. See Figures 4 and 7 and Table 5. EPA has concluded that activities occurring there are not contributing to nonattainment of the PM 10 

### standard in Pinal County.

EPA is also proposing to find that the San Carlos A pache lands, which lie to the east of the Hayden and Miami NAAs, 2 

### remain “unclassifiable.” The population density of the reservation is very low. See Table 5. Additionally, the San Carlos Apache reservation is located about 40 miles east of the proposed nonattainment area and is sepa rated from it by mountainous terrain and existing nonattainment areas.

At this time, EPA is deferring its decision regardi ng redesignation of the Ak-Chin and GRIC, as well as the TON’s Florence Village and San Lucy Far m, pending consideration of issues unique to tribal lands, completion of formal consultation with the tribal governments, and consideration of certain exceptional events flags affecting the G RIC lands.

Under EPA’s proposal, the Apache Junction area of P inal County remains part of the Phoenix

PM 10 

### nonattainment area, and the existing Hayden and Mi ami PM 10 

### nonattainment areas are unchanged. The remainder of the County retains its designation of “unclassifiable” for the 1987

24-hour PM 10 

### NAAQS.

2 A narrow strip of the San Carlos Apache Reservatio n is included within the eastern boundary of the Ha yden PM 10 nonattainment area, which lies to the east of the p roposed nonattainment area. See Figure 12. Its sta tus is not changed by this action.4Figure 2. EPA Proposed Nonattainment Area Boundary1011017977886060810CochiseCountyGilaCountyGrahamCountyMaricopaCountyPimaCountyPinalCountyTohono O'OdhamGila Riverdeferred tribal areaFlorence Villagedeferred tribal areaAk-Chin deferredtribal areaSan Lucy Farmdeferred tribal area0 2010 MilesFlorence Villagedeferred tribal areaSources: USEPA's Air Quality Systems (AQS) database(2010), TANA (2006), U.S. Department ofCommerce, U.S. Census Bureau, Geography Division (2008), USDA (2010).Stationary PM-10 Emission source (> 1 ton/year)Violating PM-10 monitorAttaining PM-10 monitorUnpaved RoadsIncorporated City BoundariesWildernessExisting PM-10 nonattainment areaTribal LandsDeferred tribal areasCounty boundaryTownship and RangeArizona's recommended boundaryAgricultureEPA Proposed PM-10 nonattainment areaAIR1000045_4 2 September 2010

### 5

EPA Technical Analysis for Pinal County

Factor 1: Air Quality Data

This factor considers the 24-hour PM 10 

### rate of expected exceedances for air quality monito rs in Pinal County and nearby areas based on data for the years 2007-2009, which were certified on April 9, 2010, by Pinal County in accordance with 4 0 CFR 58.15. The rate of expected

exceedances indicates whether a monitor attains the specified air quality standard. The 24-hour

PM 10 

### standard is met when the 3-year average of the expe cted exceedances is equal to or less

than one. An “exceedance” of the 24-hour PM 10 

### standard is a daily value that is above 150 micrograms per cubic meter (μg/m 3 

### ) after rounding to the nearest 10 μg/m 3



### .

The monitors listed in Table 1 are identified by th eir air quality system (AQS) 3 

### ID number, which consists of state code, county code, site cod e, and poc (parameter occurrence code) number (state-county-site-poc). Monitors that have either a POC 1 or POC 2 designation are part of Pinal County’s state or local air monitoring sta tions (SLAMS) network or GRIC’s tribal monitoring network, which consist of filter-based f ederal reference method (FRM) monitors that operate on a 1-in-3 or 1-in-6 day sampling schedule . The SLAMS/POC 1 or POC 2 monitors are primarily used for NAAQS comparison. The monitors i n Table 1 that have a POC 3 designation are considered special purpose monitors (SPMs). All SPMs in Pinal County are designated federal equivalent methods (FEMS). 4 

### Monitors eligible for providing design value data generally include SLAMS at population-oriented locations with a federal reference method (FRM) monitor. All data from SPMs using an FRM are eligib le for comparison to the relevant NAAQS, subject to the requirements set out in the October 17, 2006 Revision to Ambient Air Monitoring Regulations (71 FR 61236). 5



### The 24-hour PM 10 

### expected exceedances for Pinal County are summarize d in Table 1. The third column shows the number of days that are expected t o exceed the standard, based on monitored exceedances. Pinal County has flagged a number of exceedances for the years 2007-2009 as “high wind” exceptional events. 6 

### Without a more in-depth data analysis, it is diffi cult to determine which of the flagged days would be consid ered exceptional events under the Exceptional Events Rule (EER). However, given the overwhelming number of expected exceedances at multiple monitoring stations, even t he exclusion of all flagged data would not bring Pinal County into attainment of the 24-hour P M 10 

### standard.

3 AQS is an EPA database of ambient air quality data

. 4 All PM 10 SPMs in Pinal County are R & P TEOM 1400a (A/B) co ntinuous analyzers, EPA designation number EQPM-1090-079, that produce hourly data.

5 Quality-assured SPMs are comparable to the NAAQS. 40 CFR 58.20 (c) states that “[a]ll data from a SPM using an FRM, FEM, or ARM which has operated more than 24 months is eligible for comparison to the relevant NAAQS...” subject to certain conditions. All SPM moni tors in Pinal County have been operating for more t han 24 months, and are otherwise eligible. Thus, data from the monitors are comparable to the 24-hour PM 10 NAAQS.

6 On March 22, 2007, EPA adopted a final rule, Treatment of Data Influenced by Exceptional Events (EER) to govern the review and handling of certain air quali ty monitoring data for which the normal planning an d regulatory processes are not appropriate. Under the rule, EPA may exclude data from use in determinations of Nat ional Ambient Air Quality Standard (NAAQS) exceedances an d violations if a state demonstrates that an “excep tional

event” caused the exceedances. See 72 FR 13560.

### 6 Table 1. Pinal County - PM 10 Air Quality Monitoring Data

Site Name AQS ID PM 10 Expected Exceedances

2007-2009

Casa Grande 04-021-0001-1

04-021-0001-3 0

4.7 Apache Junction 04-021-3002-1 0 Coolidge 04-021-3004-1 2

Mammoth 04-021-3006-1 0 Marana (Pinal Air Park) 04-021-3007-1 0

Stanfield 04-021-3008-1

04-021-3008-3 16.4

17.8

Combs School 04-021-3009-3 17.6 Maricopa 04-021-3010-3 12.6 Pinal County Housing (PCH) 04-021-3011-1

04-021-3011-2

04-021-3011-3 6.5

5.9

15.6

Riverside 04-021-3012-1 0

Cowtown 04-021-3013-1

04-021-3013-3 112.9

139.8 Eloy 04-021-3014-1 0 Bapchule* (GRIC monitors) 04-021-7004-1

04-021-7004-2 6.6

7.9 *EPA is deferring its decisions regarding redesigna tion of the Ak-Chin and Gila River Indian Community lands, as well as TON’s Florence Village and San Lucy Farm, pending consideration of issues unique to tribal lands, com pletion of formal consultation with the tribal governments, and consideration of exceptiona l events flags.



### Violating monitors are clustered in the central and western portion of Pinal County. See Figures

1 and 3. Monitors located in the southern and easte rn portions of the county show attainment

with the 24-hour PM 10 

### NAAQS, lending weight to a partial county redesign ation.

### 7

Figure 3. PM 10 

### Monitors and Expected Exceedances

A summary of the 24-hour PM 10 

### expected exceedances for nearby counties is presen ted in Table

2.

Table 2. Nearby Counties – PM 10 Air Quality Monitoring Data, 2007 – 2009

County Name Total Number of

PM 10 Monitoring

Sites Number of Sites

in Violation of

PM 10 NAAQS Violating Monitor(s) Within

Existing PM 10 Non-Attainment Areas (NAAs)

Cochise 2 1 1:Yes (Paul Spur NAA) Gila 4 1 1:Yes (Hayden NAA)

Graham 1 0 N/A Maricopa 23* 14 13: Yes (Phoenix NAA) 1: No (Buckeye) Pima 11 2 1:Yes (Rillito NAA) 1:No (Santa Clara School, Tucson)

*Includes sites located on both State and Tribal la nds



### Almost all of the surrounding counties have monitor s that violate the PM 10 

### 24-hour standard, with the exception of Graham County, which lies to the east of Pinal. For the most part, these Coolidge: 2

Cowtown: 139.8 Maricopa: 12.6

Stanfield: 17.8 Casa Grande: 4.7 Combs School: 17.6

Bapchule (GRIC): 7.9

Pinal County Housing (PCH): 15.6

Eloy: 0 Mammoth: 0 Riverside: 0 Apache Junction: 0

Marana - Pinal Air Park: 0 Pinal County

Pima County Maricopa County Gila County

Graham County

Cochise County 0 10 20 5 Miles

AIR1000045_7 17 August 2010 Sources: USEPA's Air Quality Systems (AQS) database (2010), TANA (2006) Violating PM-10 monitor

Attaining PM-10 monitor

Existing PM-10 nonattainment area

Tribal lands

County boundary

### 8

monitors are included in nonattainment areas previo usly determined to be partial county designations to account for local conditions and ai r quality impacts. Given previous determinations regarding the more localized nature of the nonattainment problems in surrounding counties, they most likely do not contr ibute to exceedances of the PM 10 

### standard within Pinal County and should not be included in t he proposed nonattainment area.

Nearby nonattainment areas are shown in Figure 1. A portion of Maricopa County and the Apache Junction area of Pinal County, which is cont iguous with the Phoenix urban area, form the Phoenix planning area, a serious PM 10 

### nonattainment area. The Rillito planning area, a

moderate PM 10 

### nonattainment area, is located in Pima County, jus t south of Pinal County. Each area has its own planning process in place to attai n the standard. EPA determined in 2006 that

the Rillito moderate nonattainment area had attaine d the PM 10 

### standard. 7 

### In 2007, the Rillito monitor measured the only exceedance of the NAAQS s ince 2000. The exceedance was flagged as caused by an exceptional event, and the State of Arizona submitted a limited maintenance plan and redesignation request to EPA for the Rillito PM 10 

### nonattainment area in June of 2008.

Eastern Pinal County and southern Gila County share portions of two other nonattainment areas: the Hayden moderate PM 10 

### nonattainment area and the Miami moderate PM 10 

### nonattainment

area. EPA determined in 2007 that the Miami PM 10 

### area in Gila and Pinal Counties had attained

the PM 10 

### standard. 8 

### The State of Arizona submitted a limited maintenan ce plan and redesignation request for the Miami PM 10 

### nonattainment area in July of 2008. Current data i ndicate the Miami

area continues to attain the PM 10 

### standard.

Both Arizona’s recommended nonattainment area and E PA’s proposed nonattainment area encompass all violating monitors. However, section 107(d)(1)(A) of the Clean Air Act requires that areas that are contributing to ambient air qua lity must also be included within a

nonatttainment area. As described in more detail be low, EPA believes that Arizona’s recommended boundary excludes sources that are cont ributing to violations measured within the potential nonattainment area. In order to ensure co ntributing sources are included in the nonattainment area, EPA is proposing a nonattainmen t area boundary that encompasses more area to the east, south, and west.

Factor 2: Emissions data

For this factor, EPA evaluated emissions data for p rimary PM 10 

### from the violating area within Pinal County and from potentially contributing near by areas. “Primary PM 10 

### ” represents direct

emissions of PM 10 

### and includes: “PM 10 

### emissions carbon,” “PM 10 

### emissions other,” primary sulfate (SO 4 

### ), and primary nitrate (NO 3 

### ). (Although primary sulfate and primary nitrate, which are emitted directly from stacks rather than formin g in atmospheric reactions with SO 2 

### and nitrogen oxides (NO

x 

### ), are part of “PM 10 

### emissions total,” they are not shown in Table 3 as separate items). Emissions of SO 2, 

### NO

x 

### , VOCs (volatile organic compounds) and NH 3 

### (ammonia), which are precursors of secondary PM 10 

### , are included for informational purposes in Appendix A but were not considered because the PM 10 

### problem in Pinal County is primarily a fugitive dust problem.

7 See 71 FR 44920, August 8, 2006.

8 See 72 FR 14422, March 28, 2007.

### 9

Table 3 shows total emissions of PM 10 

### as well as individual source categories in Pinal C ounty that emit direct (primary) PM 10 

### . The emissions data were derived from the most cur rent version of the national emissions inventory - 2005 National Emissions Inventory, version 2 (NEIv2). 9

Table 3. Pinal County Primary PM 10 Emissions (2005 NEI version 2)

Includes Filterables + Condensibles*

Source Category Emissions (tons per year) % of Total Primary

PM 10 Emissions
Nonpoint
Unpaved Roads 6,253 28%

Construction 5,439 25%

Agriculture – Crop Tilling & Livestock

Dust 5,008 23%

Paved Roads 2,171 10%

Industrial Process – not elsewhere

classified 955 4%
Waste Disposal - Open Burning 906 4%

Wildfires 466 2%
Other Nonpoint 149 1%

Nonroad
Non-Road Equipment – Diesel 171 1%

Misc. Nonroad 106 0%

Onroad

On-Road Vehicles – Diesel 135 1%

On-Road Vehicles – Gasoline 85 0%

Point
Waste Disposal 205 1%

Misc. Point 39 0%

TOTAL: 22,088 100% * Filterable PM is particles that are directly emit ted as a solid or liquid at stack or release condit ions and captured on the filter of a stack test train. C ondensable PM is material that is in the vapor phas e at stack conditions but condenses and/or reacts upon c ooling and dilution in the ambient air to form a solid or a liquid particulate immediately after dis charge from the stack.



### The Arizona Department of Environmental Quality’s ( ADEQ’s) boundary recommendation technical support document (TSD) provides a “prelim inary” 2007 PM 10 

### emissions inventory. Reproduced below, this emissions inventory identifi es significant sources of PM 10 

### emissions in the county as including paved and unpaved road dust , active and fallow agricultural fields, sand and gravel facilities, concentrated animal feeding operations, cattle feedlots, and construction. 10

9 http://www.epa.gov/ttn/chief/net/2005inventory.html #inventorydata . Retrieved February 3, 2010.

10 Arizona Air Quality Designations Technical Support Document -Boundary Recommendation for the Pinal Co unty
24-hour PM 10 Nonattainment Area; March 15, 2010. Submitted to EPA March 26, 2010.

### 10

Table 4. Pinal County Preliminary 2007 PM 10 Emissions Inventory

Source Categories Emissions (tons per year) % of Total Primary PM 10 Emissions

Onroad 42,130 83% Tilling, Harvesting, and Agriculture 2,538 5%

Stationary Industrial Sources (including sand and gravel facilities) 2,342 5%

Concentrated Animal Feeding Operations 2,045 4%

Construction Emissions 1,757 3%

Portable Industrial Sources 38 0% Off-highway Vehicles 23 0%

Total 50,873 100%



### While the NEI and ADEQ emissions inventories disagr ee in magnitude, there is general agreement in terms of significant sources of PM. Th ese include generally:

• Onroad (including paved and unpaved road) emissions ;

• Agriculture (including tilling and harvesting as we ll as concentrated animal feeding operations and livestock dust);

• Stationary industrial sources, including waste disp osal; and

• Construction emissions.

Figures 4 and 5 illustrate the concentration of sig nificant sources of PM 10 

### in the central-western portion of Pinal County, supporting a partial count y nonattainment area. Appendix B contains additional maps showing individual source category emissions and locations.11Figure 4. Pinal County Agriculture and Cattle Operations101101797788606081010CochiseCountyGilaCountyGrahamCountyMaricopaCountyPimaCountyPinalCounty0 10 205 MilesAIR1000045_6 17 August 2010Sources: USEPA's Air Quality Systems (AQS) database(2010), TANA (2006)Additional Cattle OperationsFeedlotsDairiesViolating PM-10 monitorAttaining PM-10 monitorUnpaved RoadsExisting PM-10 nonattainment areaCounty boundaryTribal landsAgriculture12Figure 5. ADEQ Map of Preliminary 2007 Emissions Inventory for Pinal CountySource: ADEQ Boundary Recommendation for the PinalCounty 24-hour PM10Nonattainment Area, March 15, 2010

### 13

Speciation analysis shows that the PM 10 

### in Pinal County contains a significant crustal component. The 2003 Source Apportionment Study, con ducted from October to November of 2003, concluded that the dominant PM 10 

### source in Pinal County was soil, with the exceptio n of the Cowtown monitor which was significantly influen ced by cattle feedlot emissions. 11 

### For four of the five monitors studied, crustal emissions con tributed between 62 and 73% of the total PM 10 

### concentration, while feedlot or other manure source s contributed between 9 and 20%. At the fifth monitor, Cowtown, the feedlot contribution wa s 59%, with crustal components adding

32%. 12 

### These findings were reinforced by information gath ered in 2009 during an EPA-funded RARE project. 13



### Figure 6 presents the PM 10 

### source contributions for the Pinal County Housing (PCH) monitor.

Figure 6. PM 10 

### Source Contributions, Pinal County Housing (PCH) M onitor. 14

Soil Geological soil ColPP Coal fired power plant

Feedlot Feedlot soil AmSulf Ammonium sulfate

MV Emi Motor vehicle

combustion emissions AmNitr Ammonium nitrate

VgBr Vegetative burning Other Unclassified sources



### These source signatures align with the sources iden tified in the emissions inventories. Crustal

PM 10 

### contributions may be associated with unpaved and p aved roads, construction, and some stationary industrial sources (such as sand and gra vel facilities). Agriculture (including tilling

11 Pinal County Air Quality Control District Source A pportionment Study: July 29, 2005, page 43.

12 Pinal County Air Quality Control District Source A pportionment Study: July 29, 2005

13 "Chemical Analysis for Source Attribution of Fine and Coarse Particulate Matter in Pinal County, AZ" Andrea L. Clements, Yuling Jia, Matthew P. Fraser, Pierre Her ckes, Michael Sundblom, and Paul A. Solomon, presen tation to American Aerosol Research Association (AARA) 28th A nnual Conference, Minneapolis, Minnesota, October 2 6 - 30, 2009.

14 Pinal County Air Quality Control District Source A pportionment Study: July 29, 2005, p. 37.

### 14

and harvesting), concentrated animal feeding operat ions, livestock dust, and stationary industrial sources such as composting facilities may also emit both crustal PM 10 

### and feedlot/manure PM 10 

### emissions. Both emissions inventories and source ap portionment studies indicate that these types of sources, which are concentrated in the western p ortion of the county, are responsible for the

elevated PM 10 

### levels in Pinal County.

While EPA finds that the PM 10 

### emissions inventory for Pinal County and ADEQ’s corresponding maps are helpful in defining the boun daries of the new nonattainment area, we do not believe that they justify ADEQ’s conclusions ab out its recommended boundaries. ADEQ claims that the emissions inventory and maps demons trate that sources in the eastern and southern regions of the county do not “significantl y contribute” to violations in the other regions of the county. See page ES-3 of ADEQ’s technical re port. EPA notes, however, that CAA section 107(d)(1)(A) defines a nonattainment area a s one that does not meet, or that “contributes to” ambient air quality in a nearby area that does not meet the NAAQS. The definition of nonattainment areas is not limited to areas that, i n ADEQ’s words, “significantly” contribute to a violating area. Moreover, ADEQ’s maps show that are as immediately to the east and south of the recommended area (but still within the western half of the county) include the same types of emissions sources, with similar emissions densities , as those that predominate within the recommended area. For example, figure 3-3 (page 8 o f State’s technical report) shows emissions

densities similar to those estimated within the Sta te’s recommended boundaries to the east in Coolidge and Florence, as well as south to Eloy. In addition, figures 3-4, 3-7, and 3-10 (on pages 11, 14, and 17, respectively, of the State’s techni cal report) illustrate the locations of unpaved roads (with average daily traffic volumes greater t han 100) and show that higher relative

concentrations of PM 10 

### emissions from such sources as vehicle entrainment of dust over paved and unpaved roads, tilling and harvesting, and conc entrated animal feeding operations (CAFOs) extend to central, and south central Pinal County. Thus, the emissions inventory data and related maps do not support the State’s recommended boundar ies but rather argue for a larger nonattainment area consisting of the western half o f the county.

In contrast, EPA’s proposed boundaries include all of the areas for which emissions data show relatively higher PM 10 

### emissions from the types of sources contributing t he most to the overall

PM 10 

### emissions inventory. For instance, based on the in formation sources described above in the State’s technical report, EPA’s proposed boundaries include the areas of relatively higher emissions densities in and around Coolidge, Florenc e, and Eloy that reflect the same types of

PM 10 

### -generating activities (vehicle entrainment of dust over paved and unpaved roads, tilling and harvesting, and CAFOs) as found within the smal ler nonattainment area boundaries recommended by the State.

### 15

Factor 3: Population density and degree of urbaniza tion

Table 5 shows the 2008 population density for munic ipalities and reservations within Pinal County.

Table 5. Population Density within Pinal County Entity Area in

Square

Miles 2008

Population Density 2008 Population

Pinal County

Total 5,369.6 65.3 350,558

Apache

Junction 34.2 958.4 32,776

Casa Grande 109* 377.5 41,152 Coolidge 65* 157.9 10,261 Eloy 110* 115.9 12,750
Florence 50* 415.6 20,781 Kearny 2.79 1,177.5 3,297
Mammoth 1.08 2,339.1 2,573 City of Maricopa* 43* 1,059.8 45,571

Queen Creek 26* 937 Pinal Co: 5,700 Maricopa Co: 18,661 Total: 24,361 Superior 1.93 1,766.3 3,335

Ak Chin 87.2 48.3 1,591
GRIC** 581.1 37 21,665

San Carlos Apache** 2,896.6 3.6 10,416

Tohono

O’odham** 4,453 3.1 13,635

Source: U.S. Census Bureau and ADEQ’s PM 10 boundary recommendation TSD dated March 15, 2010 *Area in square miles was taken from Table 3-5 of A DEQ’s PM 10 boundary recommendation
**Population for entire reservation, including port ions that lie outside of Pinal County



### .

Figure 7 illustrates that, as a whole, Pinal County is sparsely populated. Within Pinal County, about 95% of the population resides in the more urb anized areas that lie in the western/central portion of the county where a number of relatively densely populated areas are located. Even within those more densely populated areas, the numb ers of inhabitants are relatively low (see Table 5).16Figure 7. Population density, PM10monitors, and existing PM10nonattainment areasBAPCHULECochiseCountyGilaCountyGrahamCountyMaricopaCountyPimaCountyPinalCountyCASAGRANDECOOLIDGEFLORENCEAPACHEJUNCTIONSUPERIORQUEENCREEKMARICOPAKEARNYMAMMOTHELOY0 2010 MilesAIR1000045_8 17 August 2010Sources: USEPA's Air Quality Systems (AQS) database (2010),TANA (2006)Violating PM-10 monitorAttaining PM-10 monitorCity BoundaryExisting PM-10 nonattainment areaTribal landsCounty boundaryPeople per square mile50 - 250251 - 500501 - 2,0002,001 - 5,0005,001 - 50,00050,001 - 200,000ELOY

### 17

EPA believes that the size, density, and location o f population can be indicative of emissions activity that contributes to violations of the 24-h our PM 10 

### NAAQS in an area. For example, because on-road (paved and unpaved road) emissions contribute significantly to the PM 10 

### emissions inventory in Pinal County, population dat a can give an indication of whether it is likely that an area is causing or contributing to v iolations of the 24-hour PM 10 

### standard. Based solely on this factor, certain portions of Pinal Co unty would not be considered for redesignation as nonattainment given their low population. Altho ugh areas with low population can nonetheless have activities that result in high emi ssions that contribute to violations of the NAAQS, EPA believes that, outside of the existing P M 10 

### nonattainment areas, the majority of

PM 10 

### -related emissions activities in Pinal County occur within the more densely populated central and western portion of the county, which is more urbanized and also includes the majority of agricultural lands, roads, and cattle o perations, lending weight to a partial county redesignation. See Factor 2 discussion and Figures 4 and 5.

In its technical report, ADEQ concludes that the ea stern and southern portions of the county are largely undeveloped and have very low population de nsities, and finds that this information provides support for the State’s recommended bounda ries. However, like the emissions data discussed above, we believe that the data do not ju stify the restricted nature of the State’s recommended boundaries, which exclude much of the w estern half of the County. Specifically,

EPA believes that the State’s recommended exclusion of areas in the eastern and southern sections of the western half of the county is contr adicted by evidence showing that land use development in Pinal County extends further east an d south than the State’s recommended boundaries. For example, the State’s recommended bo undaries fail to include the agricultural and more urbanized uses in and around Eloy and the futu re growth areas along the two Interstate corridors. See figures 3-13 and 3-14 from the State ’s technical report. In contrast, EPA’s proposed boundaries would include all of the wester n half of Pinal County (excluding TON’s main reservation and the Apache Junction portion of the Phoenix PM 10 

### nonattainment area) and thereby would include the areas with relatively hig her population densities and most of the areas where significant levels of growth are expected.

Factor 4: Traffic and commuting patterns

This factor considers the number of commuters in ea ch surrounding county who drive to Pinal County, the percent of total commuters in each coun ty who commute to Pinal County

, the percent of total commuters in each county who commu te into the statistical area in which Pinal county is located, as well as the total vehicle miles traveled (VMT) 15 

### for each county, in millions of miles per year (see Table 6).

15 The 2005 VMT data used for Tables 6 and 8 of this a nalysis has been derived using a methodology such a s that

described in “Documentation for the 2005 Mobile Nat ional Emissions Inventory, Version 2, December 2008

, prepared for the Emission Inventory Group, U.S. EPA . This document can be found at: at ftp://ftp.epa.gov/EmisInventory/2005_nei/mobile_sec tor/documentation//2005_mobile_nei_version_2_report .pdf.

### 18

Table 6. Traffic and Commuting Patterns – 2005 County 2005 VMT

(millions of miles) Number

Commuting

to Pinal County Percent

Commuting

to Pinal County Number

Commuting

into

Statistical

Area* Percent

Commuting

into

Statistical

Area
Pinal 3,126 35,960 60.1 55,880 93.4 Maricopa 32,392 7,750 0.6 1,389,480 98.9
Cochise 1,906 40 0.1 260 0.6
Gila 536 330 1.9 1,390 7.9

Graham 373 - 0.0 150 1.4
Pima 8,759 1,970 0.5 3,810 1.0 *Pinal and Maricopa Counties comprise the Phoenix-M esa-Scottsdale CBSA



### Data on commuting illustrate that the majority of P inal County’s working residents are employed within the county. Data from 2000 16 

### illustrate that a sizeable number (19,918) commute to Maricopa County to the north, with 7,750 commuters entering Pinal from Maricopa County. About 2,600 Pinal County residents commute to Pima County to the south, while 1,970 Pima County residents commute into Pinal County. The nu mber of commuters to and from other surrounding counties is negligible. See Table 6 an d Figure 8.

According to the 2005 NEIv2, on-road emissions (fro m paved and unpaved roads) are the largest

source of PM 10 

### in Pinal County and account for 8,426 tpy, or 38% of the overall PM 10 

### inventory. Traffic and VMT are therefore important considerati ons in the process of determining the nonattainment area boundary. ADEQ’s preliminary 20 07 PM 10 

### emissions inventory attributes 83% (42,130 tpy) to on-road sources. See Factor 2 d iscussion.

The principal route for traffic through Pinal Count y (serving in-county as well as out-of-county commuters) is Interstate 10, which bisects the west ern portion of the county and connects metropolitan Phoenix (largely in Maricopa County) t o the north with metropolitan Tucson (in Pima County) to the south. Unpaved roads are also concentrated in the western side of the county. The eastern portion of the county has far f ewer unpaved roads, and the main highways (AZ 77, 79, and 177) experience much lower traffic volumes. See Figure 8 and Appendix B, Figures 2 and 4. Figure 9, reproduced from Arizona’ s boundary recommendation, illustrates the distribution of on-road emissions in Pinal County.

ADEQ cites traffic and commuting patterns as a fact or supporting the exclusion of the eastern half of the county from the new nonattainment area. While EPA agrees that it is reasonable to distinguish between the eastern and western sides o f the county, EPA believes that the entire western half of the county, and not a small portion of it, as the State recommends, should be redesignated to nonattainment. EPA finds that traff ic and commuting patterns do not make a case for the state’s recommendation, but rather lend sup port to the creation of a larger nonattainment area generally encompassing the western half of the County. See figure 3-17 from the State’s technical report, which shows much higher employmen t densities projections for year 2030 in the western half of the county than those in the ea stern half but which also show higher

16 Arizona Air Quality Designations Technical Support Document; Boundary Recommendation for the Pinal Co unty
24-hour PM 10 Nonattainment Area, Table 3-6. March 15, 2010

### 19

employment densities east and south of the State’s recommended boundaries (but still within the western half of the county).20Figure 8. Traffic, commuting patterns, and PM10monitorsTucsonPhoenix19,9182,60135,96137,7513331,97443791771888788347170101387607010817PinalCountyPimaCountyMaricopaCountyGilaCountyGrahamCountyCochiseCounty0 10 205 MilesAIR1000045_917 August 2010Sources: ADOT (2009),AQS (2010), FHA (2006),USGS (2001), TANA (2006)Violating PM-10 monitorAttaining PM-10 monitor2002 Daily Truck Traffic0 - 2,0002,001 - 5,0005,001 - 10,00010,001 - 25,0002002 Daily Traffic0 - 2,0002,001 - 5,0005,001 - 10,00010,001 - 25,00025,001 - 282,000County boundary2,601Daily CommuteCount21Figure 9. Preliminary PM10Emissions Inventory for Pinal County (2007) – Paved and Unpaved On-Road Sources (tons peryear)Source: ADEQ Boundary Recommendation for the PinalCounty 24-Hour PM10 Nonattainment Area

### 22

Factor 5: Growth rates and patterns

This factor considers population growth for 2000-20 08 and growth in vehicle miles traveled for 1996-2005 for Pinal County.

Arizona has experienced rapid population growth in recent years (26.7% between 2000 and 2008); however, vast areas remain sparsely inhabite d. In Pinal County, the population increased 82% between 2000 and 2008, with almost all the popu lation growth occurring in the central and western portion of the county. See Factor 3, Figur e 7. Table 7 shows the 2008 population growth and density for municipalities within Pinal County. Decreases in population density for some areas reflect the expansion of the boundaries of mu nicipalities, rather than reductions in population.

Table 7. Population Growth within Pinal County Entity Area in

Square

Miles

2000/2009-10 Population Density Population

2000 2008 2000 2008

Pinal County

Total 5,369.6 33.5 65.3 179,727 350,558

Apache

Junction 34.23 929.3 958.4 31,814 32,776

Casa Grande 48.17/109* 523.7 377.5 25,224 41,152 Coolidge 5.03/65* 1,549.1 157.9 7,786 10,261 Eloy 71.67/110* 144.8 115.9 10,375 12,750
Florence 8.29/50* 2,056.2 415.6 17,054 20,781 Kearny 2.79 805.4 1,177.5 2,249 3,297
Mammoth 1.08 1,626.5 2,339.1 1,762 2,573 City of Maricopa 4.04/43* 257.6 1,059.8 1,040 45,571

Queen

Creek** 25.7 167.3 944.2 Pinal Co: 119 Maricopa Co: 4,197 Total: 4,316 Pinal Co: 5,700

Maricopa Co: 18,661 Total: 24,361

Superior 1.93 1,684.6 1,766.3 3,254 3,335 Source: U.S. Census Bureau and ADEQ’s PM 10 boundary recommendation TSD, dated March 15, 2010. *2009-2010 area in square miles is from Table 3.5 o f ADEQ’s PM 10 boundary recommendation TSD. ** Queen Creek straddles the Pinal and Maricopa Cou nty border, with about 23.4% of the city’s area lyi ng within Pinal County. The population figures in the table a re pro-rated to reflect the proportion of the city that is within each county, but density is not pro-rated.



### Along with the growth in population, VMT has increa sed dramatically.

Table 8. Population and VMT Values and Percent Cha nge. Location Population

(2005) Population

Density (2005) Population

% change (2000 - 2005) 2005 VMT

(millions mi) VMT

% change (1996 to 2005) Pinal 240,044 45 32 3,126 54

### 23

ADEQ submitted maps showing population densities bo th under current conditions and projections for the year 2030 when the population o f Pinal County is anticipated to exceed 1,000,000. Under existing conditions, higher popula tion densities are found in the west central portion of the county, but there are also populatio n centers in the northern (Apache Junction and Queen Creek) and southern portions (Eloy) of the co unty. ADEQ’s maps show that future growth is expected to be concentrated in the Inters tate 8 and 10 corridors which extend through the west central and southern portions of the count y, although a certain amount of growth is also expected in the Falcon Valley area further to the e ast. See Figures 3-14 and 3-17 in ADEQ’s technical report.

EPA finds that growth rates and patterns do not mak e a case for the state’s recommendation, but rather lend support to the creation of a larger non attainment area generally encompassing the western half of the County. By redesignating the we stern portion of Pinal County as

nonattainment for PM 10 

### , EPA would include most of the population and the rapidly growing areas along the I-10 and I-8 corridors.

Factor 6: Meteorology

Like most of Arizona, Pinal County is generally hot and dry. Average maximum temperatures at the Maricopa weather station (part of the National Weather Service Cooperative Network) range from 67 degrees Fahrenheit ( o 

### F) in January to 107 o 

### F in July, and minimum temperatures from

25 o 

### F in January to 75 o 

### F in August. The rainiest month is July, with just over an inch of rain; the yearly total averages 8 inches. Despite the dryness , there is substantial agriculture in Pinal County, supported by irrigation from groundwater an d the Central Arizona Project. Weather systems typically arrive from the west, except duri ng "monsoon" season, which occurs during June through August or September, when moisture fro m the south arrives and creates

thunderstorms.

EPA examined wind data collected at the Cowtown mon itoring site and also at stations in the AZMET meteorological network. In the western porti on of the County, at the Cowtown and Maricopa monitors, typically there is wind from the southeast during the cooler evening hours, corresponding to downhill drainage flow down the Gi la River valley. Flow at other times is less consistent, though there can be steady winds from t he west in late morning through the afternoon, and on occasion from the north or south. In the center of Pinal County, at Coolidge (near the Pinal County Housing monitor), flow can b e from any direction, though it tends to range from the southwest to southeast in the second and third quarters of the year. In the north, at Queen Creek (near the Combs School monitor, wher e the Phoenix serious PM 10 

### nonattainment area lies immediately to the west and to the north) , flow is mainly from the southeast. There is some northwest flow in May through July; exceedance s may occur then though they are more common in winter. Finally, in the south at Marana (near the Pinal Air Park monitor, which does not violate the NAAQS), flow is mainly from the eas t-southeast, with easterly flow predominant in the winter. With a few exceptions, flow is not from the north and northwest, making transport

of PM 10 

### from the metropolitan Phoenix area unlikely under most circumstances. See Figure 10.

### 24

While there are periods of high wind and gusts, esp ecially during “monsoon” season, wind speeds are most often 3 meters per second or less, with higher speeds usually from the west. High wind and gusts, especially over disturbed dese rt areas, can lead to substantial fugitive dust

emissions. Sometimes there are “haboob” dust storm s that have the appearance of an approaching “wall of dust,” in which visibility is very low and gusts very strong. It is possible

that some PM 10 

### exceedances are caused by wind-generated dust near the monitors, with some moderate-range transport.

Figure 10. Pinal County Wind Roses for 2006 – 2008

### 25

The State recommends including the agricultural bas in region of the county where stagnation conditions are known to impact PM 10 

### concentrations. While we agree that the new nonatt ainment area should include the agricultural basin region w here stagnation conditions occur, we find that

the State’s recommended boundaries do not in fact a ccomplish this. As shown on page 14 of ADEQ’s technical report, the agricultural basin reg ion of the county, roughly defined based on tilling and harvesting emissions within the county, lies in the western half of the county, and also

extends south of Interstate 10 towards the southern county line. Moreover, as discussed in the following paragraph, a review of available wind dat a supports the inclusion of areas to the south and east of the violating monitors (i.e., beyond th e State’s recommended boundaries) based on the prevalence of winds from the southeast quadrant

.

EPA has considered the information provided by ADEQ but also reviewed available wind data for Pinal County and finds that winds are similar t hroughout central and western Pinal County in that the predominant wind directions are from the s outheast quadrant. See Figure 10. The predominance of southeast winds support boundaries that extend south and east of the violating

monitors because PM 10 

### sources, including agricultural activities and unp aved roads, are found in

those directions. EPA’s recommended boundaries enco mpass the types of sources that are

believed to cause or contribute to the monitored vi olations and that are located east and south of the violating monitors, whereas the State’s recomme nded boundaries largely exclude these sources. See Figures 1, 4, and 5.

Lastly, EPA recognizes that high wind events do occ ur in Pinal County, and that some of these events may result in monitored particulate matter e xceedances that qualify as caused by exceptional events under EPA’s exceptional events r ule. 17 

### However, as ADEQ itself acknowledges, even if EPA were eventually to determ ine that all of the exceedances that ADEQ has flagged are caused by “exceptional events,” the area would still clearly be in violation of the

PM 10 

### NAAQS.

Factor 7: Geography and topography

The geography/topography analysis evaluates the phy sical features of the land that might have an effect on the airshed and, therefore, on the distri bution of PM 10 

### over the Pinal County area.

Pinal County has topographical barriers significant ly limiting air pollution transport within its airshed and from neighboring airsheds, though these barriers are not absolute. Therefore, this factor provides some support for EPA’s suggested bo undary for the nonattainment area.

As shown in Figure 11, Pinal County generally has f airly low relief and is at around 1,200 feet elevation, but it is punctuated by various mountain s and ranges having peaks generally from

17 On March 22, 2007, EPA adopted a final rule, Treatment of Data Influenced by Exceptional Events , to govern the review and handling of certain air quality monitori ng data for which the normal planning and regulator y processes are not appropriate. Under the rule, EPA may exclud e data from use in determinations of National Ambie nt Air Quality Standard (NAAQS) exceedances and violations if a state demonstrates that an “exceptional event ” caused the exceedances, and satisfies other criteria set f orth by the rule. See 72 FR 13560.

### 26

3,000 to 5,000 feet. Some 50 miles east of the vio lating monitors, the eastern quarter of the county becomes more mountainous, ultimately rising to some 6,000 feet near the eastern borders with Gila and Graham Counties. The mountain ranges generally run southeast-northwest, and do not form closed basins. Rather, there are broad de sert valleys. In the vicinity of the violating monitors, there are the Sacaton Mountains to the ea st, rising to 2,235 feet, the Maricopa Mountains to the west, with elevations up to 2,400 feet. Nearest is the southeastern tip of the Sierra Estrella Mountains, starting at about 10 mil es northwest of the Cowtown monitor; they have peaks to 3,000 and 4,500 feet. To the north, between Pinal and Maricopa Counties, are the South Mountains rising to 2,500 feet; they run west -southwest to east-northeast, unlike most of the ranges. They are only 10 miles long, but along with the Sierra Estrella they do form a partial barrier between Pinal County and metropolitan Phoen ix to the north.

Overall, the mountains within the county can redire ct winds, and form a partial barrier to transport from the eastern portions of Pinal County

.

ADEQ finds that topographic considerations support the State’s inclusion of the basin region of the county, which is characterized by open-ended va lleys with few topographic barriers within the recommended boundaries. Conversely, ADEQ finds that topographic considerations support

the State’s exclusion from the recommended boundari es of the eastern portion of the county, which is characterized by rough terrain and steep m ountain ranges reaching over 7,000 feet in

elevation.

EPA generally agrees with ADEQ’s description of the topography of Pinal County. We believe that the various mountain ranges found on each side of the county inhibit transport of PM 10 

### (which is largely crustal in composition – see Figu re 6) from outside the county to the violating monitors within the county. Within the county itsel f, we believe that the mountains in the eastern quarter of the county, which rise to approximately 6,000 feet near the eastern borders with Gila and Graham counties, inhibit intra-county transport from sources located in the eastern quarter to the violating monitors. See figure 11 of EPA’s TSD. (The portion of the San Carlos Apache Reservation that lies within Pinal County is locate d in the eastern quarter of the county.)

However, the existence of the steep mountain ranges in the eastern quarter of the County does not justify ADEQ’s recommendation to exclude from r edesignation a much larger section of the western half of the County. EPA believes that, taki ng other factors into account, the western half of the County, located in the basin region that fea tures few topographic barriers, should be redesignated to nonattainment. Indeed, it is arguab le that topography alone would lend support to redesignating a far larger area than EPA is proposi ng, one that would encompass the entire county, excepting only the eastern quarter. However , EPA believes that topography when

evaluated in the context of the various other facto rs, supports redesignation of the western half of the county, rather than the much more restricted bo undaries that ADEQ suggests.27Figure 11. TopographyFlorence(Tohono O'Odham)VillageSan(Tohono O'Odham)LucyFarmRillito planningareaPhoenix planning areaMiamiplanningareaHaydenplanningareaSanCarlosFortMcDowellSalt RiverGilaRiverAk-ChinTohonoO'OdhamCochiseCountyGilaCountyGrahamCountyMaricopaCountyPimaCountyPinalCountyViolating PM-10 monitorAttaining PM-10 monitorExisting PM-10 nonattainment areaCounty boundaryTribal lands12,000+ feet~100 feet3,000 feetSources: USEPA's Air Quality Systems (AQS) database(2010), TANA (2006)AIR1000045_2 23 August 20100 10 205 Miles

### 28

Factor 8: Jurisdictional boundaries

In evaluating the jurisdictional factor, EPA consid ered the planning and organizational structure of Pinal County and the State of Arizona to ensure that the implementation of controls within the prospective nonattainment area can be carried out i n a cohesive manner. Figure 12 shows boundaries for Pinal and neighboring counties, near by nonattainment areas, and Indian lands.

The Arizona Department of Environmental Quality has overall jurisdiction over environmental programs in the state of Arizona, as well as jurisd iction over certain source types, including smelters, refineries, coal-fired power plants, and retains authority for regulating emissions from agricultural operations. Three Arizona counties, Ma ricopa, Pima, and Pinal, have their own air pollution control programs and operate pursuant to agreements with ADEQ. The lead air quality planning agencies responsible for state implementat ion plans (SIPs) for Maricopa County and Pima County are the metropolitan planning organizat ions (MPO), the Maricopa Association of Governments (MAG) and the Pima Association of Gover nments (PAG), respectively. There is no MPO and thus no lead air quality planning agency for SIP purposes in Pinal County. Therefore, ADEQ is responsible for developing SIPs for Pinal County. Pinal County has permitting authority, and can adopt control measure s by rule, but is preempted from adopting rules regulating certain categories of sources that are regulated by the State.

Four tribes are located in Pinal County. The Ak-Chi n Indian Community tribal lands lie entirely within the County, and are encircled by the propose d nonattainment area. Approximately twothirds of the Gila River Indian Community tribal la nds lie within the boundaries of Pinal County; the other third is in Maricopa County and is part o f the Maricopa County serious PM 10 

### nonattainment area.. A portion of the main reservat ion of the Tohono O’odham Nation lies in southeastern Pinal County, south of the proposed no nattainment area. Two additional areas (San Lucy Farm and Florence Village) lie to the east and northeast of the main TON reservation, within the proposed nonattainment area. A portion o f the San Carlos Apache tribal lands lie within the eastern part of Pinal County, east of th e proposed nonattainment area. See Figure 12.

Of the four tribes, only the Gila River Indian Comm unity has treatment as a state (TAS) status for Clean Air Act section 107 designations and an a ir quality monitoring network that reports quality-assured data to EPA’s Air Quality System (A QS). We recently proposed approval of GRIC’s submitted tribal implementation plan. See 75 FR 48880, August 12, 2010. None of the other tribes currently monitor for PM 10 

### , although the Ak-Chin Indian Community has been developing an air monitoring program.

As noted above, EPA is deferring action on the Ak C hin and Gila River Inidan Community lands within Pinal County, and the San Lucy Farm and Flor ence Village portions of the TON, which

like to the east and northeast of the main reservat ion in order to allow time for formal consultation to occur. Neither ADEQ nor Pinal Count y has jurisdiction over tribal lands.

The Apache Junction area of Pinal County is part of the Phoenix PM 10 

### nonattainment area. The Hayden and Miami PM 10 

### nonattainment areas lie to the east.

### 29

In its technical report, ADEQ notes that five citie s and towns (Casa Grande, Coolidge, Eloy, Florence, and City of Maricopa), as well as a porti on of a sixth (Queen Creek) are located in central and western Pinal County. ADEQ indicates th at the incorporated boundaries of these municipalities have been taken into account in deve loping the nonattainment area boundaries. However, EPA’s review of the incorporated boundarie s of these municipalities (see, e.g., Figure 2) shows that the State’s recommended boundaries om it portions of the City of Maricopa and Coolidge, and most of Florence and Eloy. In contras t, EPA’s proposed nonattainment area boundaries encompass all of these cities and towns, where most of the county’s population

resides. Inclusion of entire cities and towns withi n the nonattainment area boundaries would facilitate attainment planning to the extent that s uch local governments will ultimately be relied upon for development and/or implementation of speci fic PM 10 

### control measures.30Figure 12. Jurisdictional BoundariesFlorence(Tohono O'Odham)VillageSan(Tohono O'Odham)LucyFarm1011017977886060881010WhiteMountainSanCarlosFortMcDowellSaltRiverGilaRiverAk-ChinTohonoO'OdhamCochiseCountyGilaCountyGrahamCountyMaricopaCountyPimaCountyPinalCountyRillito planningareaPhoenixplanning areaMiamiplanningareaHaydenplanningarea0 10 205 MilesFreewaysViolating PM-10 monitorAttaining PM-10 monitorWildernessUS Forest Service Class 1 AreasNational Park Service Class 1 AreasExisting PM-10 nonattainment areaTribal landsCounty boundaryAIR1000045_3 23 August 2010Sources: USEPA's Air Quality Systems (AQS) database(2010), TANA (2006)

### 31

Factor 9: Level of control of emission sources

Under this factor, we consider the existing level o f control of emissions. The emissions data used by EPA in this technical analysis and pro vided in Table 3 (under Factor 2) represent emissions levels taking into account any control strategies implemented in Pinal and nearby counties before 2005 on stationary, mobi le, and area sources. EPA is not aware of any additional information on emissions co ntrols that is relevant to assessing sources contributing to the monitored violations. EPA is proposing to designate those portions of Pinal County that encompass the emissio ns sources and activities that

contribute to the violations in this area.

Pinal County AQCD has established rules for dust ab atement purposes that apply within a subarea of Pinal County established under state l aw (Arizona Revised Statutes section 49-541) and referred to as “Area A.” Within Pinal C ounty, “Area A” generally refers to an area encompassing the Pinal County portions of A pache Junction and Queen Creek. Pinal County has also adopted a number of ordinance s that are also intended to reduce dust generated within “Area A.” These include ordin ances placing restrictions on residential fireplaces, leaf blowers, open burning, vehicle commute trips, and vehicle idling. For one township located within “Area A,” t he township included in the Phoenix

Area PM 10 

### nonattainment area (i.e., Township 1 north, range 8 east; referred to as “Apache Junction”), Pinal County AQCD has adopted f urther dust abatement rules. 18 

### The State’s recommended boundaries include a portion, b ut not all, of “Area A.” In contrast, EPA’s proposed boundaries for the new nonattainment area would encompass all of “Area A,” thereby facilitating review and modificat ion of these existing PM 10 

### emissions controls within the broader SIP attainment planning context.

Conclusion

Based on the weight of evidence, and an evaluation of all the factors discussed above, EPA is proposing to redesignate the western portion of Pinal County, Arizona (excluding the main TON reservation), as nonattainment for the 1987 24-hour PM 10 

### NAAQS, as set forth in Figure 2. Inventory and speciation data po int to onroad emissions (paved and unpaved), agriculture (including feedlots), constru ction, and industrial processes as the primary contributors to nonattainment. The vast maj ority of these activities are occurring on the western side of Pinal County leading EPA to conclude that a nonattainment area (NAA) that incorporates the western portion of the County is appropriate.

The expected exceedance values of monitors deployed throughout the area reinforce the partial county redesignation. EPA’s intended nonat tainment area boundary encompasses all violating monitors that are not otherwise inclu ded in previously designated

nonattainment areas. The intended nonattainment are a also includes areas that are not

18 The township referred as to Apache Junction would be unaffected by our proposed action and would remain part of the Phoenix planning area, which is designated as a “serious” PM 10 nonattainment area.

### 32

violating the standard, but by virtue of the source mix and meteorology, may be contributing to the violations recorded elsewhere.

CAA section 107(d)(3)(C) provides that after notify ing the Governor of State of its intent to redesignate an area, EPA shall promulgate the re designation, if any, of the area or portion thereof, submitted by the Governor, “making such modifications as EPA may deem necessary....” Pursuant to CAA section 107(d)( 3), we have reviewed the State’s recommendation (dated March 23, 2010) and related t echnical report (submitted on March 26, 2010).

Both EPA and the State agree that sources outside o f the county do not contribute to

PM 10 

### violations at the violating monitors within the co unty, and that sources in the eastern half of the county do not contribute to the violating monitors (which are concentrated in the central and western portions of the county). But while EPA and the State both use the nine-factor analysis for evaluat ion of the prospective nonattainment area boundaries, we reach quite different results.

As explained above, EPA does not believe that the S tate’s recommended boundaries encompass the full geographic area from which emiss ions-generating activities contribute

to the monitored PM 10 

### violations. More specifically, we believe that the Governor’s recommended boundaries, which cut through municipal ities and contiguous expanses of agricultural fields, exclude sources that have been identified as dominant sources of PM 10 

### and that are contributing to elevated levels of PM 10 

### at violating monitors.

We believe that our proposed boundaries, which are defined as all land geographically located within Pinal County west of the north-south line defined by the boundary between Townships 10E and 11E, but excluding TON’s main reservation and excluding the existing Apache Junction portion of the existin g Phoenix PM 10 

### nonattainment area, encompass the areas in which PM 10 

### violations are being monitored, as well as the are as that contribute to the monitored violations, and th at they are thus consistent with the

definition of nonattainment areas in CAA section 10 7(d)(1)(A). Our conclusion is based on EPA’s analysis of the factors as set forth in th e body of this document. In sum, we base our proposed boundaries on the following consi derations: (1) monitored violations occur in the west, central and northern portions of the western half of the county, not in the eastern half (i.e., outside of existing PM 10 

### nonattainment areas); (2) the emissions from agricultural operations, feedlots, dairies, an d other cattle operations, as well as roads, are concentrated in the western half of the county; (3) population densities are much greater in the western half of the county than in the eastern half and growth is expected to be concentrated primarily along the Int erstate corridors that extend through the western half of the county; (4) Interstate 10, which connects Pinal County with the employment centers in metropolitan Phoenix and Tucs on, bisects the western half of Pinal County; (5) predominant southeasterly winds s upport inclusion of PM 10 

### sources in areas to the south and east of the violating monito rs; (6) the western half of Pinal County encompasses the incorporated boundaries of all of t he cities in Pinal County (Apache Junction, Casa Grande, Coolidge, Eloy, Maricopa), a s well as the larger towns (Florence and Queen Creek) thereby potentially facilitating i mplementation of future control

### 33

measures; and (7) dust abatement measures already i n effect in “Area A” (within Pinal County) can readily be applied, as necessary and ap propriate, throughout the other portions of the western half of Pinal County. Figur e 2 compares the State’s recommended boundaries to EPA’s proposed boundaries.

EPA therefore deems it necessary and appropriate to propose boundaries that differ from

the State’s recommended boundaries and that we beli eve better satisfy air-quality data, planning, control and other air-quality related con siderations. CAA Section 107(d)(3). Under CAA section 107(d)(3)(C), EPA must notify the State whenever EPA intends to modify State recommendations concerning boundaries for areas to be redesignated, at least 60 days prior to EPA promulgation of final re designations. EPA will provide notification to Arizona shortly after the Federal R egister notice proposing our action is signed.

### Appendix A 1 Appendix A Emissions in Pinal County: Primary PM 10 

### , NO

x 

### , NH 3 

### , SO 2 

### ,, VOCs.

### Appendix A 2

**Pinal County: Emission Totals Per County (tons per year). 2005 NEI version 2.** 

**County Primary PM**  **10**

**Emissions NO**

**x**

**NH 3**  **SO 2**  **VOC**

Pinal 22,088 12,545 5,646 757 9,217

**Pinal County: Primary PM 10**  **(Includes Filterables + Condensibles) Sources. 20 05 NEI** 

**version 2.**

**Source Category Emissions**  **(tpy) % of Total Primary** 

**PM 10**  **Emissions**
**Nonpoint**
Unpaved Roads 6,253 28%

Construction 5,439 25%
Agric

- Crop Tilling & Livestock Dust 5,008 23%

Paved Roads 2,171 10%

Indus Process

- NEC 955 4%
Waste Disposal

- Open Burning 906 4%

Wildfires 466 2%
Other Nonpoint 149 1%

**Nonroad**

Non

- Road Equipment

- Diesel 171 1%

Misc. Nonroad 106 0%

**Onroad**

On

- Road Vehicles

- Diesel 135 1%

On

- Road Vehicles

- Gasoline 85 0%

**Point**
Waste Disposal 205 1%

Misc. Point 39 0%

**TOTAL: 22,088**  **100%**

### Appendix A 3

**Pinal County: Nitrogen Oxides (** NO

x **) Sources. 2005 NEIv2.**

**Source Category Emissions**  **(tpy) % of Total**  NO

x **Emissions, Pinal**

**County**

**Onroad**

On-Road Vehicles - Diesel 3,889 31%

On-Road Vehicles - Gasoline 3,715 30%

**Nonroad**

Planes, Trains, & Ships 2,275 18%

Non-Road Equipment - Diesel 1,775 14%

Non-Road Equipment - Gasoline 142 1%

**Nonpoint**

Waste Disposal - Open Burning 235 2%

Wildfires 113 1%

Fuel Comb - Industrial Boilers, ICEs 81 1%

Fuel Comb - Residential Fossil 65 1%

Other Nonpoint 35 0%

**Point**

Fuel Comb - Electric Utility 173 1%

Misc. Point 47 0%

**TOTAL: 12,545 100%** 

**Pinal County: Ammonia (** NH 3 **) Sources. 2005 NEIv2.**

**Source Category Emissions**  **(tpy) % of Total** 

NH 3 **Emissions, Pinal**
**County**

**Nonpoint**

Livestock Waste 4,344 77%

Fertilizer Application 845 15%

Other Nonpoint 75 1%

**Onroad**

On-Road Vehicles - Gasoline 305 5%

On-Road Vehicles - Diesel 9 0%

**Point**

Fuel Comb - Electric Utility 65 1%

**Nonroad**

Misc. Nonroad 2 0%

**TOTAL: 5,646 100%** 

### Appendix A 4

**Pinal County: Sulfur Dioxide (** SO 2 **) Sources. 2005 NEIv2.**

**Source Category Emissions**  **(tpy) % of Total**  SO 2

**Emissions, Pinal County**

**Nonroad**

Non-Road Equipment - Diesel 244 32%

Planes, Trains, & Ships 163 22%

Non-Road Equipment - Gasoline 1 0%

**Nonpoint**

Fuel Comb - Industrial Boilers, ICEs 130 17%

Wildfires 48 6%

Other Nonpoint 21 3%

**Onroad**

On-Road Vehicles - Diesel 105 14%

On-Road Vehicles - Gasoline 38 5%

**Point**

Misc. Point 7 1%

**TOTAL: 757 100%** 

**Pinal County: Volatile Organic Compounds (VOC) Sour ces. 2005 NEIv2.** 

**Source Category Emissions**  **(tpy) % of Total VOC** 

**Emissions, Pinal**
**County**

**Onroad**

On-Road Vehicles - Gasoline 3,539 38%

On-Road Vehicles - Diesel 200 2%

Nonroad

Non-Road Equipment - Gasoline 1,476 16%

Non-Road Equipment - Diesel 195 2%

Planes, Trains, & Ships 96 1%

**Nonpoint**

Wildfires 978 11%

Gas Stations 687 7%

Waste Disposal - Open Burning 642 7%

Solvent - Non-industrial 518 6%

Surface Coating - Industrial 206 2%

Miscellaneous Sources 186 2%

Surface Coating - Architectural 176 2%

Other Nonpoint 239 3%

**Point**

Misc. Point 80 1%

**TOTAL: 9,217 100%** 

### Appendix B 1 Appendix B. ADEQ Maps of PM 10 

### Sources.

From Arizona Department of Environmental Quality, B oundary Recommendation for the

Pinal County 24-hour PM 10 

### Nonattainment Area: March 15, 2009. http://www.azdeq.gov/environ/air/plan/download/0329 10c.pdfAppendix B2Figure 1. ADEQ Map of significant sources of PM10in Pinal County (preliminary 2007 emissions inventory)Appendix B3Figure 2. ADEQ Map of Onroad Emissions - Unpaved Roads (preliminary 2007 Emissions Inventory)Appendix B4Figure 3. ADEQ Map of Construction Sources (preliminary 2007 Emissions Inventory)Appendix B5Figure 4. ADEQ Map of Onroad Emissions – Paved Roads (preliminary 2007 Emissions Inventory)Appendix B6Figure 5. ADEQ Map of Tilling and Harvesing PM10Emissions (preliminary 2007 Emissions Inventory)Appendix B7Figure 6. ADEQ Map of Stationary Industrial SourcePM10Emissions (preliminary 2007 Emissions Inventory)Appendix B8Figure 7. ADEQ Map of Concentrated Animal FeedingOperation (CAFO)PM10Emissions. (preliminary 2007 EmissionsInventory