This page is intentionally blank.Enclosure 1

SIP Completeness ChecklistThis page intentionally left blank.STATE IMPLEMENTATION PLAN COMPLETENESS CHECKLIST

SUBMITTAL OF STATE IMPLEMEN TATION PLAN (SIP) REVISION

2012 State Implementation Plan for the

Nogales PM 10 Nonattainment Area

1. SUBMITTAL LETTER FROM GOVERNOR/DESIGNEE

See cover letter.

2. EVIDENCE OF ADOPTION

See cover letter.

3. STATE LEGAL AUTHORITY FOR ADOPTION/IMPLEMENTATION

A.R.S. §§ 49-404 and 49-406 were approved into the Arizona SIP on 6/08/2000. ADEQ's Infrastructure SIP for the 1997 and 2006 PM 2.5 NAAQS and the 1997 8-hour Ozone NAAQS submitted to EPA Region IX on August 24, 2012, included a certified copy of authorizing statute A.R.S. § 104.

4. COMPLETE COPY OF ACTUAL REGULATION

Same as above.

5. EVIDENCE THAT ARIZONA ADMINISTRATIVE PROCEDURE ACT REQUIREMENTS (ARS §§ 41-1021 through 1036) WERE MET FOR RULE

See Appendix K.

6 EVIDENCE OF PUBLIC HEARING PER 40 CFR 51.102

See Appendix K.

7 PUBLIC COMMENTS AND AGENCY RESPONSE

See Appendix K.

8. IDENTIFICATION OF POLLUTANTS REGULATED BY RULE

Particulate matter 10 microns and smaller in size (PM10)

9. IDENTIFICATION OF SOURCES/ATTAINMENT STATUS

See Enclosure 3.10. WRITTEN SUMMARY OF RULE/RULE CHANGE

Not applicable.

11. RULE CHANGES INDICATED BY UNDERLINING AND CROSS-OUTS

Not applicable.

12. RULE’S EFFECT ON EMISSIONS

See Enclosure 3.

13 DEMONSTRATION THAT NAAQS, PSD INCREMENTS AND RFP ARE PROTECTED

See Enclosure 3.

14. EVIDENCE THAT EMISSIONS LIMITATIONS ARE BASED ON CONTINUOUS EMISSIONS REDUCTION TECHNOLOGY

Not applicable.

15. MODELING SUPPORT

Not applicable.

16. IDENTIFICATION OF RULE SECTIONS CONTAINING EMISSION LIMITS, WORK PRACTICE STANDARDS, AND/OR RECORD KEEPING/REPORTING REQUIREMENTS

Not applicable.

17. COMPLIANCE/ENFORCEMENT STRATEGIES

See Enclosure 3.

18 ECONOMIC TECHNICAL JUSTIFICATION FOR DEVIATION FROM EPA POLICIES

No known deviation from EPA policy.

## Final

2012 State Implementation Plan Nogales PM 10 

## Nonattainment Area

August 24, 2012This page is intentionally blank.

### iii Executive Summary.............................................................................................................. .................. ES-1

Introduction 1.0 ............................................................................................................... ................................1
1.0 Physical, Demographic, and Economic Description of the Nogales NA..................................1
1.1 Physical, Demographic, and Economic Description of the Nogales NA...........................1
1.1.1 Climate and Physiography................................................................. ......................1
1.1.2 Population ............................................................................... ..................................2
1.1.3 Santa Cruz County and City of Nogales Economy............................................ ....3
1.2 Nogales Regulatory Background ......................................................................... .................4
1.2.1 EPA's Particulate Matter NAAQS ........................................................... ...............5
1.2.2 Nogales NA Statutory Boundary ........................................................... ................5

1.2.3 General SIP Approach - Regulat ory Requirements and Guidance.......................6
2.0 Air Quality Monitoring ...................................................................................... 9
2.1 Monitoring Site, Equipment, and Quality Assurance Procedures.......................... 9
2.2 Air Quality Data....................................................................................... .............. 9

2.3 24-hour PM 10 NAAQS Compliance..................................................................... 12
3.0 Emissions Inventory.................................................................................................... ....... 13
3.1 Significant Emissions Sources ............................................................................ 13
3.2 Nogales NA Future Year (2011) PM10 Emissions Projections.......................... 15

4.0 Demonstration of Attainment in Accordance with Section 179B of the Clean Air Act .........16
4.1 Population Growth in Nogales Municipality, Sonora....................................................16
4.2 Nogales Municipality, Sonora, Emissions Inventories............................................... ...17
4.3 Comparison of Ambos Nogales Emissions Inventories..................................... 19

4.4 PM 10 Exceedance Analyses - Monitoring Data, Wind Speed, and Temperature ....... 19
Changes
4.5 Wind Direction and Wind Rose Analyses.......................................................... 24

4.6 Conceptual Model of 2 007-2009 Exceedance Days .......................................... 27
4.7 Review of Exceedance Days Differing from 25-Day Conceptual Model.......... 29
4.8 Expected Exceed ance Days "But For" International Transport from Mexico ... 33

4. 8.1 Daily Analysis of Expected Exceedances ............................................. 33
4.8.2 Hourly Analys is of Excepted Exceedances........................................... 34

4.9 Conclusion ........................................................................................... .............. 36

5.0 Control Measures..................................................................................................... ........ 37

5.1 Definition and Selection of RACM/RACT......................................................... 37
5.1.2 RACM Analysis for the Nogales NA...................................................... 38

### iv 5.2 Control Measures Adopted into the SIP and Implemented by ADEQ................. 38
5.2.1 Require RACT for Stack and Fugitive PM10 from Permitted................ 38
Stationary Sources/Require RACT for Haul Roads and Staging Areas
5.2.2 Require Dust Control Measures for Material Storage Piles.................... 39
5.2.3 Limit Use of Recreational Vehicles on Open Land ................................ 39
5.3 Status of 1993 Nogales NA SIP Control Measures Implemented by the City ... 40
5.3.1 Pave or Chemically Stab ilize Unpaved Roads; Pave, Vegetate or ...................40
Chemically Stabilize Access Points Where Unpaved Traffic Surfaces
Adjoin Paved Roads
5.4 Control Measures Implemented by Agencies but not included in the SIP for Credit....43

5.4.1 General Services Administration - Reduce Idling Time of Diesel-Powered ...43

Vehicular Traffic at Border Entrances

5.4.2 Provide for Storm Water Drainage to Prevent Water Erosion onto Paved ......43
Unpaved Roads/Provide for Traffic Rerouting or Rapid Clean Up of
Temporary Sources of Dust on Paved Roads

5.4.3 Require Permanent Unpaved Haul Roads, and Parking or Staging Areas.......44

at Commercial
5.4.4 Require Haul Trucks to be Covered..................................................... ..............44
5.5 Nogales NA RACM/RACT Conclusion..................................................................... .....44
6.0 Reasonable Further Progress and Contingency Measures......................................................46
7.0 Transportation Conformity Pr ocedures and Motor Vehicl e Emissions Budget .................47
8.0 Conclusions and Summary............................................................................................ ................49

List of Figures
Figure ES1 – Map of Nogales NA .......................................................................................... ...ES- 2
Figure ES2 – Nogales Post Office Filter-Based Monitor PM 10 Monitoring Data.......................ES-3

Trends 1985-2010
Figure ES3 – Nogales Post Office BAM Monitoring Data Trends 2005-2010 ......................... ES-3
Monitoring Trends 2005-2010
Figure ES4 – 2008 Annual Emissions I nventory for the Nogales, Arizona, PM 10 ................... ES-4

Nonattainment Area
Figure 2.1 – Nogales Post Office Filter-Based Monitor PM 10 Monitoring Data Tr ends 1985-2010 .....12
Figure 2.2 – Nogales BAM Monitor PM 10 Monitoring Data Trends 2005-2010 .....................................12

### v List of Figures Continued
Figure 3.1 – 2008 Annual Emissions Inventory for the Nogales, Arizona PM 10 Nonattainment Area.....13
Figure 4.1 – Comparison of Ambos N ogales Population Growth 1995-2010............................................17
Figure 4.2 – Nogales, Sonora 2008 High and Low I nventories Compared to Nogales, AZ 2008 ............19 Inventory
Figure 4.3 – PM 10 Exceedances at the Nogales, Arizona Post Office, by Month and Year ......................20
Figure 4.4 – Hourly Ambient PM 10 Concentrations on 29 Exceedance Dates ...........................................21
Figure 4.5 – Hourly Ambient PM 10 Concentrations on 26 Similar Exceedance Days, .................22 Excluding the Following Days: January 1, 2007; May 22, 2008; and January 1, 2009 Figure 4.6 – Hourly Wind Speed Vari ations on 29 Exceedance Dates.......................................................23
Figure 4.7 – Hourly Temperature Va riations on 29 Exceedance Days ......................................................24
Figure 4.8 – Wind Rose of Wind Speed vs. Wind Direction at the Nogales, Arizona, Post......................25
Office BAM Monitor for all 29 Exceedance Days
Figure 4.9 – Pollution Rose of PM 10 Concentration vs. Wind Direction at the Nogales ....................26
Arizona Post Office BAM for all 29 Exceedance Days
Figure 4.10 – Average Hourly PM 10 Concentration, Wind Speed, and Temper ature at the Nogales, ..........28

Arizona Post Office BAM vs. Time of Day for all Exceedances Excluding January 1,
2007, May 22, 2008, and January 1, 2009
Figure 4.11 – January 1, 2007 PM 10 Concentrations and Wind Speeds Compared to 26................. 30
Exceedance Day Average PM 10 Concentrations and Wind Speeds from Figure 4.11
Figure 4.12 – January 1, 2009 PM 10 Concentrations and Wind Speeds Compared to 26................. 31
Exceedance Day Average PM 10 Concentrations and Wind Speeds from Figure
Figure 4.13 – May 22, 2008 PM 10 Concentrations and Wind Speeds Co mpared to 26 Exceedance................ 32
Day Average PM 10 Concentrations and Wind Speeds from Figure 4.10
Figure 4.14 – January 26, 2008 PM 10 Concentrations and Wind Speed Compared Average ....................32

PM 10 Concentrations and Wind Speeds from Figure 4.11
Figure 5.1 – Image of an Intersection of Paved and Unpaved Road in Rio Rico .................................42
Figure 8.1 – Comparison of Ambos Nogales Population Growth 1995-2010 ......................................49

List of Tables
Table ES-1 – Arizona Administrative Code Rules Approved into the Arizona SIP...............ES-5 Table 1.1 – Climatological Data for Nogales, AZ (1952-2010) ..................................................... 2 Table 1.2 – Population of Nogales, Rio Rico, and Santa Cruz County 1990-2010 ......................... 2 Table 1.3 – Population Proj ections for the Region .......................................................................... 3 Table 1.4 – Population of Nogales Municipality, Sonora, Mexico.................................................. 3

### vi List of Tables Continued Table 1.5 – Building Permits Issued in N ogales and Santa Cruz County 1990-2010...................... 4 Table 1.6 – Clean Air Act (CAA) Regulatory Requirements .......................................................... 7 Table 2.1 – Nogales Post Office Monitor Site Specifications.......................................................... 9 Table 2.2 – Nogales Filter-Based 24-hour PM 10 Monitoring Data 1985-2010.............................. 10 Table 2.3 – Nogales Continuously Operating BAM Monitor PM 10 Monitoring Data 2005-2010 ..........11 Table 3.1 – Significant PM 10 Emissions Sources in the Nogales NA ........................................... 14
Table 3.2 – PM 10 Emissions Sources in the Nogales NA .............................................................. 14 Table 3.3 – Projected PM 10 Emissions 2008 and 2011 .................................................................. 15
Table 4.1 – 2008 and 2011 PM 10 Emissions Inventories for Nogales, Sonora .............................. 18
Table 4.2 – 24-hour Concentration and Hour ly Concentrations Disaggregated by ....................... 33 Southerly Wind Direction Quadrant for Exceedance Days Differing from Conceptual Model Table 5.1 – Arizona Administrative Code Rules Approved into the Arizona SIP for PM 10 Sources .....37
Table 5.2 – PM 10 Generating Point Sources Operating in the Nogales NA in 2008...................... 39
Table 5.3 – Calculated PM 10 Emissions Assuming Paved Road Efficiency for Roads in ............. 41 the City of Nogales, Arizona 1993-1996
Table 5.4 – Calculated PM 10 Emissions Assuming Paved Road Efficiency for Roads in........................42 Rio Rico within the Nogales NA Table 7.1 – 2011 Nogales NA Moto r Vehicle Emissions Budget .......................................................48

List of Appendices
Appendix A – Clean Air Act, Section 179B Attainme nt Determination for the Nogales, Arizona

PM 10 Nonattainment Area Appendix B – 2008 & 2011 PM 10 Emissions Inventories for the Nogales Nonattainment Area, Santa Cruz County, Arizona Appendix C – 2008 and 2011 PM 10 Emissions Inventories, Nogales Municipality, State of Sonora, Mexico Appendix D – Analysis of Ambient PM 10 Levels, Topography, and Meteorological Data in Nogales, Arizona: 2007-2009 Appendix E – ADEQ Technical Support Docume nt for Control Measure Emission Reductions Appendix F – Correspondence Appendix G – Supplementary Information Appendix H – NNA Monitoring Data 2008-2010 Appendix I – 1996 Reasonable Further Progress Report Appendix J – Potential New Source Appendix K – Public Process Documentation

### 7 EXECUTIVE SUMMARY

The Nogales PM 10 Nonattainment Area (Nogales NA) is located 66 miles south of Tucson, covering approximately 76 square miles along the in ternational border with Mexico in Santa Cruz County. The City of Nogales and portions of Rio Rico , an unincorporated community, occupy most of the nonattainment area, as depicted in Figure ES-1. N ogales, Arizona and Noga les, Sonora, Mexico, collectively referred to as Ambos Nogales, form a mi cropolitan area bisected by the international border.

Pursuant to the 1990 Clean Air Act (CAA) Am endments, by operation of law all areas where
violations of the PM 10 NAAQS had been recorded were designate d as moderate nonattainment areas for

PM 10 , including the Nogales NA. Because Arizona did not submit a required moderate PM 10 plan for the Nogales NA by the November 15, 1991, deadline, EPA issued a finding of failure to submit (57 FR 19906; May 8, 1992). The Arizona Department of Environmental Quality (ADEQ) subsequently submitted a State Implementation Plan (SIP ) for the Nogales NA on June 14, 1993. 1 EPA found the SIP to be complete but did not take action on it. 2 One of the purposes of this document is to ultimately serve as a replacement of the 1993 Nogales NA SIP. This plan demonstrates that the annual expected
exceedances are less than one but fo r emissions originating in Mexico.

This PM 10 SIP for the Nogales NA is organized as follows and is intended to meet the requirements established by the CAA for moderate PM 10 nonattainment area plans.

Chapter 1 provides an overview of the Nogales NA and Santa Cruz County. It discusses the climate, physiography, population, and economy of the area and the impact each has on ambient PM 10 concentrations. Chapter 1 also includes an account of the regulatory history of the PM 10 NAAQS and the Nogales NA, and describes how this SIP meets all the regulatory requirements for a PM 10 nonattainment area plans under CAA Sections 172, 189, and 179B



### .

1 “Final State Implementation Plan for the Nogales PM 10 Nonattainment Area.” ADEQ. Submitted to EPA June 14, 1993. <http://www.azdeq.gov/environ/air/plan/download/nogpm10sip_061993.pdf >

2 Correspondence. Letter from EPA to ADEQ dated November 30, 1993. See Appendix F.4.



### ES-1

### 8 Figure ES-1

ES- 

### ES-2

### 9 Chapter 2 describes how the Nogales NA am bient monitoring network meets CAA and EPA regulatory requirements, provides a description of th e monitoring equipment, and includes a physical description of the monitor sites. This chapter provides PM 10 monitoring data collected by monitors in the Nogales NA from 1985-2010. As shown in Figure ES -2, filter-based monitoring data from 2008-2010
showed observed concentrations below the PM 10 NAAQS. Additional data coll ected during 2008-2010 at a co-located continuous monitor, however, showed observed concentrations above the NAAQS, as shown in Figure ES-3. 3 Although recent trends indicate a decline in ambient concentrations, based on preliminary monitoring data, the Nogales BAM monitor recorded ex ceedances in 2011; quality assured monitoring data for the Nogales NA will be certified and submitted to EPA in 2012.

Figure ES-2 Nogales Post Office Filter-Based PM 10 Monitoring Data Trends 1985-2010

0 50 100 150 200 250 300

1 9 8 5

1 9 8 6

1 9 8 7

1 9 8 8

1 9 8 9

1 9 9 0

1 9 9 1

1 9 9 2

1 9 9 3

1 9 9 4

1 9 9 5

1 9 9 6

1 9 9 7

1 9 9 8

1 9 9 9

2 0 0 0

2 0 0 1
2 0 0 2

2 0 0 3

2 0 0 4

2 0 0 5

2 0 0 6

2 0 0 7

2 0 0 8

2 0 0 9

2 0 1 0ug/m3

24hr Max 2nd 24hr High PM10 NAAQS

Source: EPA's AQS Database.

Figure ES-3 Nogales BAM Monitoring Data Trends 2005-2010

0 50 100 150 200 250 300 350 400

2005 2006 2007 2008 2009 2010ug/m3

1st Hi 2nd Hi 3rd Hi 4th Hi PM10 NAAQS

Source: Ibid.

3 Due to data completeness deficiencies in 2010 BAM mo nitoring data, ADEQ reviewed, certified, and quality assured data for 2007-2009 collected by the Nogales BAM monitor a nd determined the Nogales NA did not meet the NAAQS during that period either.



### ES-3

### 10 Chapter 3 contains the 2008 base year PM 10 emissions inventory; provides a summary of the inventory methodology; and identifies significant a nd insignificant emission sources in the Nogales NA. Figure ES-4 depicts the 2008 emissions inventory major source categories. Chapter 3 also includes a projected emissions inventory for 2011.

Figure 3.1 2008 Annual Emissions Inventory for the Nogales, Arizona
PM 10 Nonattainment Area 1,531 tons per year total

Other 87 tpy

6% Residential Garbage Burning 24 tpy

2% Residential Construction 24 tpy

2% Residential Wood Burning 24 tpy

2% Paved Road Dust 121 tpy

8%

Commercial/

Industrial Construction 143 tpy
9% Road Construction 267 tpy

17% Unpaved Road
Dust 865 tpy

57%

Source: 2008 and 2011 PM 10 Emissions Inventories for the No gales NA, Santa Cruz County, Arizona (see Appendix B). Estimates rounded.

Chapter 4 includes a demonstratio n in accordance with CAA section 17 9B that but for emissions from Mexico, the Nogales NA would attain the PM 10 standard. The demonstration in cludes analyses of population growth, sources of PM 10 , ambient PM 10 concentrations, and meteorology in the Ambos Nogales area.

Chapter 5 describes CAA requirements for reasonably available control measures (RACM) in
moderate PM 10 nonattainment areas. The chapter cites appli cable State laws already approved into the Arizona SIP. Chapter 5 describes the selection process, implementation, and status of RACM required by the SIP submitted for the Nogales NA in 1993 and descr ibes in detail the extensive road paving projects that have been completed since that time. This chap ter includes a demonstration that the control measures meet CAA criteria to qualify as RACM and also includes supplemental control measures not intended for
inclusion in the Arizona SIP.

Chapter 6 discusses CAA requirements for cont ingency measures that provide supplementary
emissions reductions not included in a SIP attainment demonstration in the event of failure to make RFP or attainment by the prescribed attainment date.



### ES-4

### 11 Chapter 7 discusses requirements in the CAA to ensure potential emissions from federally funded transportation projects will not delay attainment of the standard in the Nogales NA or cause violations of
the PM 10 standards. To meet this obligation, the Trans portation Conformity Rule (40 CFR Part 93) directs the State to establish a limit or “budget” for onro ad emissions in the area. The emissions budget developed for this SIP assists in assuring transportation conformity requirements are met. Each new travel plan must be shown to conform with the motor ve hicle emissions budget (MVEB) at least every four years and upon any amendments, including a new regional emissions analysis.

Chapter 8 summarizes the obligations and commit ments the State is making with the submission of this SIP. Several of the applicable air quality sec tions of Arizona Revised Statutes have been amended and the numbering system has changed since the rules lis ted below in Table ES-1 were approved into the State Implementation Plan. The following rules ha ve been submitted to EPA and approved into the
Arizona SIP.

4 R18-2-702, General Provisions, reflects the current R18 Arizona Administrative Code numbering format. The R9 series of rules were subsequently renumbered as well, but have only been approved by EPA in the original numbering format. Table ES-1
Arizona Administrative Code Rul es Approved into the Arizona SIP

Rule FR Date FR Citation

R9-3-404 Open Areas, Dry Washes, or Riverbeds 4/23/1982 47 FR 17485

R9-3-405 Roadways and Streets 4/23/1982 47 FR 17485

R9-3-406 Material Handling 4/23/1982 47 FR 17485

R9-3-407 Storage Piles 4/23/1982 47 FR 17485

R9-3-410 Evaluation of Nonpoint Source Emissions 4/23/1982 47 FR 17485

R9-3-502 Standards of Performance for Unclassified Sources 10/19/1984 49 FR 41026

R9-3-522 Standards of Performance for Existing Gravel and Stone Crushing Operations 9/28/1982 47 FR 42572

R18-2-702 4 General Provisions 8/24/2004 69 FR 51952



### ES

- 5

### 1 1.0 INTRODUCTION

Chapter 1 provides a description and regulatory hi story of the Nogales Nonattainment Area (NA) and presents general regulatory requirements for PM 10 nonattainment areas.

1.1 Physical, Demographic, and Econ omic Description of the Nogales NA

Section 1.1.1 describes the climate and physiography of the Nogales NA; Sections 1.1.2 and 1.1.3 provide an overview of the demogra phics and economy of the Nogales area.

1.1.1 Climate and Physiography

The Nogales NA is located on the U.S./Mexico bord er 66 miles southeast of Tucson. This region of the Sonoran Desert is characterized by north-south elo ngated valleys surrounded by mountain ranges. Nogales is located in a valley created by the Nogales Wash , a tributary of the nearby Santa Cruz River.

The mean elevation in Nogales, Arizona is 3, 865 feet above sea level. Mountain ranges near Nogales include the Patagonia Mountains to the east and the Tumacacori, Atascosa, and Pajarito mountains to the west. Approximately twenty-five m iles to the north are the Santa Rita Mountains and Madera Canyon in the Coronado National Forest where Mount Wrightson rises to an elevation of 9,432
feet. Northwest of Interstate 19 are the Cerro Co lorado, Las Guijas, and Sierrita Mountain Ranges.

The mean elevation in Nogales, Sonora is 4,265 feet above sea level. 5 At 5,380 feet, the highest elevation in Nogales, Sonora is the Cerro de los Nogales (Nogales Hill), west of where the Obregón and Colosio routes meet, near the southern end of the city.

The elevation drops approximately 709 feet from the southernmost edge of the Nogales, Sonora urban boundary to the Nogales NA northern boundary line.

The average daily maximum temperature is 79.7 oF, based on a 62-year average of meteorological data (see Table 1.1). The highest monthly daily maxi mum average temperature (94.1 oF.) occurs in July, and the lowest monthly daily minimum average temperature (64.3 oF.) occurs in January.

The yearly average total rainfall for the Nogales area is 17.21 inches, as shown in Table 1.1. The majority of this precipitation falls in July and Augu st, when warm moist air penetrates Arizona from the Gulf of Mexico. The area receives approximately 8.5 inches of precipitation during this time. The area receives an average of only 0.22 inches of ra in in May, the driest month of the year.

5 “Statistical Municipal Workbook for Nogales, So nora,” 2005 edition, INEGI. <http://www.inegi.org.mx />

### 2 Table 1.1 Climatological Data for Nogales, AZ (1952-2010) Average Temperature oF Rain in
Inches

Month Daily Max. Daily Min. Avg. Total January 64.3 27.3 1.14 February 66.7 29.6 0.86
March 70.7 33.7 0.87 April 78.1 38.6 0.38 May 86.3 45.0 0.22

June 95.3 54.5 0.46 July 94.1 63.9 4.38 August 91.7 62.7 4.03 September 90.2 55.5 1.57
October 82.4 43.9 1.29
November 71.7 33.0 .065
December 64.6 27.6 1.37 Annual Average 79.7 43.0 17.21 SOURCE: Western Regional Climate Center. 6

1.1.2 Population

Table 1.2 includes historical and projected popul ation estimates for the Nogales area. Estimates for 1990, 2000, 2008, and 2010 were obtained from the U.S. Census Bureau. The base year for the emissions inventory is 2008. According to 2008 population estim ates, 55 percent of the Co unty’s population resides within the Nogales NA, which includes portions of Rio Rico and all of the City of Nogales. The Arizona Commerce Authority (ACA) population pr ojections, shown in Table 1.3, we re developed in 2006 based on the rate of growth during the peak of the housing market. Updated projectio ns from the ACA based on 2010 Census data will not be published until December 31, 2012.

Table 1.2 Population of Nogales, Rio Rico, and Santa Cruz County 1990-2010
1990 2000 2008 2010 City of Nogales 19,489 20,878 19,752 20,837 Santa Cruz County 29,676 38,381 43,091 43,716
Portions of Rio Rico SE and SW in Nogales NA 3,983 4,042

Source: U.S. Census Bu reau. Rio Rico population figures were estimated from U.S. Census data; see Appendix B for allocation calculations.

6 “Nogales, Arizona.” Western Regional Climate Center. n.d. June 28, 2011. < http://www.wrcc.dr i.edu/cgi-bin/cliMAIN.pl?az5924 >.

### 3 Source: Arizona Commerce Authority.

Nogales, Sonora, depicted in Figure ES-1, is Noga les, Arizona’s much larger sister city. The Nogales Municipality's population in 2010 is estimated to be 220,292. 7 Table 1.4 contains population estimates and projections obtained from Mexico’s Instituto Nacional de Estadistica y Geografía (INEGI).

Table 1.4 Population of Nogales Municipality, Sonora, Mexico
1995 2000 2005 2010 Nogales Municipality, Sonora 133,491 159,787 193,517 220,292

Source: INEGI.

1.1.3 Santa Cruz County and City of Nogales Economy

The City of Nogales was founded in 1880 when a trading post opened on the international border; two years later, a railway running through Nogales connected the U.S. and Mexico. Today the economies of Nogales, Arizona, and Nogales, Sonora are largel y interdependent. According to the ACA, 47 percent of Santa Cruz County’s annual sales tax revenue is generated from purchases made by residents of
Mexico. 8 There are two ports of entry (POE) in the ar ea, the DeConcini POE in downtown Nogales and the Mariposa POE 0.5 mile to the west. The DeConcini POE does not accept commercial trucks, all of which are required to cross the border at the Mariposa POE. From November through April, approximately 136,000 trucks haul produce from Mexico to warehouses in Nogales; approximately 200,000 U.S. trucks distribute the fresh produce to supermarkets in the United States and Canada. 7 The Nogales ports of entry serve as the gateway to 50 per cent of all fresh fruits and vegetables shipped into
the U.S. from Mexico. 8

In 2008, 74 percent of Nogales Arizona's working population was employed in the private sector. The trade, transportation, and utilities industry accounted for 43 percent of all employment; 26 percent of the working population was employed in the public se ctor, with most working for the Department of Homeland Security, Santa Cruz County, the City of Nogales, and Cochise Community College. The County’s unemployment rate was 13.1 percent in 2009, 9 higher than the State average, 10.6 percent.

7 Instituto Nacional de Estadistica y Geografia. n.d. June 1, 2011. <http://www.inegi.org.mx />.

8 “Nogales Community Profile.” Arizona Department of Commerce. September 10, 2009. June 1, 2011. <http://www.nogalesusa .com/commerce.html >

9 Census Bureau. Santa Cruz County, AZ Census Statistics. <http://census-statistics.findthedata.org/l/111/Santa-Cruz-County-AZ > Table 1.3 Population Projections for the Region

2020 2030 City of Nogales 24,783 26,356 Santa Cruz County 61,658 71,033

### 4 The number of building permits in the City of Nogales has slowed cons iderably since 2000; the number of building permits issued in 2010 was 5, co mpared to 60 in 2000, as shown in Table 1.5. Home sales in the third quarter of 2011 were 74 percent lower than the market’s peak in the first quarter of 2006. 10

Table 1.5 Building Permits Issued in Nogales and Santa Cruz County 1990-2010
1990 1996 2000 2010 City of Nogales n/a 37 60 5 Unincorporated Santa Cruz County n/a 265 301 47 Santa Cruz County 217 306 302 53

Source: U.S. Census Bureau. 11

1.2 Nogales NA Regulatory Background

EPA promulgated a revised particulate matte r NAAQS in 1987 (52 FR 24634; July 1, 1987). These primary and secondary standards apply to particulate matter 10 microns 12 or less in diameter (PM 10 ) and superseded the previous total suspended pa rticulate (TSP) standards. ADEQ began monitoring

PM 10 in the Nogales NA in 1985.

As part of the implementation policy for the 1987 PM 10 NAAQS, EPA created a tiered scale to designate nonattainment areas based on an area’s probabi lity of violating the standa rd. An area with a high probability of violating the standard was designated as a Group I area; an area with a moderate probability of violating was designated as a Group II area; and an area likely to attain th e standard was designated as a Group III area. The Nogales planning area was subsequently cl assified as a Group II Area, with a moderate likelihood of violating the PM 10 NAAQS. In accordance with Section 110 (a )(1) of the Clean Air Act (CAA), the State was required to submit a State Implementation Plan (SIP ) within three years after promulgation of the NAAQS (52 FR 24672; July 1, 1987, and 52 FR 29383; August 7, 1987) by August 7, 1990.

With the CAA amendments of 1990, areas where previous violations of the PM 10 standard had been recorded prior to January 1, 198 9, were designated nonattainment for PM 10 by operation of law and classified as “moderate”; these areas included all former Group II PM 10 planning areas like the Nogales NA (55 FR 45799; October 31, 1990) . On March 15, 1991, EPA publishe d a list of the areas designated
nonattainment for PM 10 upon enactment of the 1990 amendments , including the Nogales nonattainment area (56 FR 11101; March 15, 1991). Later, EPA codified the PM 10 nonattainment designations and moderate area classifications ( 56 FR 56694; November 6, 1991).

As stipulated in the 1990 amendments, by Nove mber 15, 1991, Arizona was required to submit a SIP for the Nogales NA demonstrating attainment of the PM 10 NAAQS by December 31, 1994

. Because

10 Citydata.com. <http://www.city-data.com/zips/85621.html >

11 U.S. Census Bureau. Web. <http://censtats.census.gov/bldg/bldgprmt.shtml? >

12 One micron is one millionth of a meter, or 0.0004 inches.

### 5 Arizona did not submit a SIP for the Nogales NA by the November 15, 1991 deadline, EPA made a finding
of failure to submit a PM 10 SIP on December 16, 1991. In response, on June 14, 1993, Arizona submitted
the ‘‘Final State Implementation Plan for the Nogales PM 10

Nonattainment Area.” (1993 Nogales NA SIP) EPA found the plan to be complete by letter date d November 30, 1993, but did not act on the plan. 13

On January 11, 2011, EPA promulgated a determ ination of attainment as of the applicable attainment date for the Nogales NA based on am bient air quality monitoring data from 1992-1994, retroactively affirming that the area had met the PM 10 NAAQS by the December 31, 1994 deadline established by the 1990 amendments of the CAA (76 FR 1532; January 11, 2011).

1.2.1 EPA’s Particulate Matter NAAQS

The CAA requires the EPA to assess the latest scien tific information and review the particulate

matter NAAQS every five years. On October 17, 2006, EPA revised the 1987 PM 10 standards by retaining the existing 24-hour PM 10 standard and revoking the annual PM 10 standard effective December 18, 2006 (71 FR 61144; October 17, 2006). Therefore, this SIP revision addresses EPA’s current primary and secondary 24-hour PM 10 NAAQS. The PM 10 NAAQS allows for a maximum 24-hour average of 150

μ g/m 3 . The 24-hour standard is attained when the expected number of days per calendar year with a 24- hour average concentration exceeding the standard is less than or equal to one (see 40 CFR 50.6 and 40 CFR Part 50, Appendix K). The primary standard wa s established to protect human health; the secondary standard was established to protect property, material s, and general welfare. Both NAAQS have a 24-hour average concentration limit of 150 μ g/m 3 . This plan addresses both the primary and secondary PM 10 NAAQS.

1.2.2 Nogales Nonattainment Area Statutory Boundary

The Nogales NA in southern Arizona is within Santa Cruz County on the international border with Mexico, and includes the City of Nogales, porti ons of the Rio Rico community, and unincorporated portions of the County. It is shown in Figur es ES-1. The nonattainment area is codified at 40 CFR 81.303 and is described by the townships and ranges listed belo w that are within the State of Arizona and lie east of 111 degrees longitude:

T23S, R13E T23S, R14E T24S, R13E T24S, R14E

13 Correspondence. Letter from EPA to ADEQ dated November 30, 1993. See Appendix F.4.

### 6 1.2.3 General SIP Approach – Regu latory Requirements and Guidance

The November 1990 CAA amendments were enacted by the United States Congress to improve air quality across the nation. One of the primary goals of this comprehensive revision to the CAA was to expand and clarify the planning provisions for thos e areas not currently meeting the NAAQS. The amendments identify specific emis sion reduction goals, require both a de monstration of reasonable further progress (RFP) and attainment, and inco rporate more stringent sanctions fo r failure to attain or to meet interim milestones. Title I, Part A, and Title I Part D, Subparts 1 and 4 of the CAA are app licable to this
SIP. Table 1.6 includes the SIP re quirements and explains how this document meets them. The pollutant specific requirement s for moderate PM 10 nonattainment areas applied to th e U.S. are found in section 189 of the CAA, and the general planning and control requir ements for nonattainment area plans are found in CAA sections 110 and 172. The following excerpt from the CAA describes requirements of SIPs submitted for
consideration under Section 179B - International Border Areas:

Sec. 179B. INTERNATIONAL BORDER AREAS

"(a) IMPLEMENTATION PLANS AND REVISIONS. — Notwithstanding any other provision of law, an implementation plan or plan revision required under this chapter shall be approved by the Administrator if—

(1) such plan or revision meets all the requiremen ts applicable to it under the Act other than a requirement that such plan or revision demonstr ate attainment and maintenance of the relevant national ambient air quality standards by the attainment date specified under the applicable provision of this Act, or in a regulation promulgated under such provision, and

(2) the submitting State establishes to the satisfaction of the Administrator that the implementation plan of such State would be adequate to attain and maintain the relevant national ambient air quality standards by the attainment date specified under the applicable provision of this chapter, or in a regulation promulgated under such provision, but for emissions emanating from outside of the United
States...

(d) ATTAINMENT OF PM 10

LEVELS - Notwithstanding any other provision of law, any State that establishes to the satisfaction of the Ad ministrator that, with respect to a PM 10

nonattainment area in such State, such State would ha ve attained the national ambient air quality standard for carbon monoxide [sic] by the applicable attainment da te, but for emissions emanating from outside the United States, shall not be subject to the provisions of section 188 (b)(2) ." 14

EPA issued administrative guidance in 1994 setting fo rth several types of information that could be used to evaluate the impact of emissions emanating from outside the U.S. and demonstrate that a

14 Carbon monoxide is an apparent typographical error; the text should read "PM 10 ".

### 7 border area's inability to meet the NAAQS w as due to emissions from outside the U.S. 15 Section 4.0 follows these guidelines to demonstrate that the N ogales NA would be in attainment of the 24-hour PM 10 NAAQS "but for" emissions from Mexico.

Table 1.6 Clean Air Act (CAA) Regulatory Requirements
CAA
Citation Action to Meet Requirement Location in
Document CAA Section 172(c), Nonatt ainment Plan Provisions 172(c)(1)
General “...Such plan provisions shall provide for the implementation of all reasonably available control measures (RACM) as expeditiously as practicable [including such reductions in emissions from existing sources in the area as may be obtained through the adoption, at a minimum, of reasonably available control technology (RACT)] and shall provide for attainment of the national primary ambient air quality standards...” Chapter 5.0 provides an explanation of
RACM/RACT for

PM 10 sources in the Nogales NA.

172(c)(2)
Reasonable
Further Progress Plan provisions shall demonstrate RFP or “annual incremental reductions in emissions...for the purpose of ensuring attainment of the applicable national ambient air quality standards by the applicable date.” In Chapter 4.0, the
State demonstrates that the Nogales NA
would be in
attainment but for
emissions from Nogales, Sonora and
that RFP is not required. 172(c)(3)
Emissions Inventory The plan provisions “...shall include a comprehensive, accurate, current inventory of actual emissions from all sources of the relevant pollutant(s)...” Base-year PM 10 emission estimates are presented in Chapter 3.0. 172(c)(5)
Permits for
New and
Modified Major Stationary
Sources The plan provisions “...shall require permits for the construction and operation of new or modified major stationary sources anywhere in the
nonattainment area...” All new sources and modifications to existing sources in Arizona are subject to state requirements for preconstruction review and permitting pursuant to AAC, Title 18, Chapter 2, Articles 3 and 4. All new major sources and major modifications to existing major sources in Arizona are subject to the New Source Review (NSR) provisions of these rules or Prevention of Significant Deterioration (PSD) for maintenance areas. Table 5.2 in Chapter 5.0 lists permitted sources in the Nogales
NA.

15 State Implementation Plans for Serious PM 10 Nonattainment Areas, and Attainment Date Waivers for PM 10 Nonattainment Areas Generally; Addendum to the General Pr eamble for the Implementation of Title I of the Clean Air Act Amendments of 1990 (59 FR 41,998; August 16, 1994).

### 8 Table 1.6 Clean Air Act (CAA) Regulatory Requirements
CAA
Citation Action to Meet Requirement Location in
Document CAA Section 172(c), Nonatt ainment Plan Provisions 172(c)(6)
Other

Measures The plan “...shall include enforceable emissions limitations, and such other control measures, means or techniques....as well as schedules and timetables for compliance, as may be necessary or appropriate to provide for attainment of such standard in such area by the applicable attainment date...” Emissions limitations
and control measures
for sources in the Nogales NA are described in Chapter
5.0. 172(c)(7) Compliance
with Section 110(a)(2), Implementati
on Plans The plan provisions “... shall also meet the applicable provisions of Section 110(a)(2).” The requirements of Section 110(a)(2)
are detailed elsewhere
in this table.

172(c)(8) Equivalent Techniques The plan may include upon application by the state “... the use of equivalent modeling, emission inventory, and planning procedures ...” as allowed by
the administrator. Chapter 4.0 includes an analysis demonstrating but for
emissions from Mexico, the Nogales
NA would meet the

PM 10 standard. 172(c)(9) Contingency

Measures The plan “... shall provide for the implementation of specific measures to be
undertaken if the area fails to make RFP or to attain the national primary ambient air quality standard ... Such measures shall be included in the plan revision as contingency measures to take effect in any such case without further action by the State or the Administrator.” Chapter 6.0 describes
the State’s contingency plan.

CAA Section 110(a)(2) – Implementation Plans 110(a)(2)(A)
Control

Measures
and
Emission
Limits Section 110(a)(2)(A) requires that states provide for enforceable emission limitations and other control measures, means, or techniques, as well as schedules for compliance necessary to meet applicable requirements of
CAA. Chapter 5.0 describes
the measures implemented to
reduce PM 10 emissions and ensure
future maintenance of the NAAQS.
CAA Section 179B – International Border Areas

179B
International
Border
Areas Section 179B of the CAA provides the State with an option to demonstrate
that a nonattainment area would meet the NAAQS but for emissions emanating from outside of the United States. Chapter 4.0
demonstrates the Nogales NA would
be in attainment but
for emissions from
Mexico.

### 9 2.0 AIR QUALITY MONITORING

The primary goal of PM 10 monitoring in the Nogales Nonattainme nt Area (NA) is to collect the data necessary to determine compliance with the PM 10 NAAQS and fulfill the regulatory requirements for

PM 10 monitoring in the nonattainment area. This chap ter provides a general description of the Nogales NA monitoring network and historical PM 10 air quality data for the years 1985 through 2010.

2.1 Monitoring Site, Equipment, a nd Quality Assurance Procedures

The Nogales NA monitors were installed and are maintained in accordance with federal siting and design criteria 16 and consistent with ADEQ’s State of Arizona Air Moni toring Network Plan for the Year 2011, which was approved by EPA on December 1, 2011. 17 Presently ADEQ operates two PM 10 monitors at the Nogales Post Office site in the center of the Nogales business district. ADEQ has operated a filter-based monitor at that location since 1985 that operates on a one-in-six day schedule. A single exceedance recorded by a monitor operating on this schedule counts as six ex ceedances and the area is in nonattainment of the

PM 10 NAAQS. A continuously operating Beta Attenuation Monitor (BAM) has been operating at the Post Office site since February 2004. ADEQ began operating a weather sta tion at the site in June 2003.

The monitor site was selected in an effort to monitor the maximum PM 10 impacts on the Nogales population. The PM 10 monitors are middle-scale monitors suited to measure concentrations within a 1/3 of a mile radius (40 CFR 58, Appendix D). Table 2. 1 features the locations, methods, and parameters
measured at the site.

Table 2.1 Nogales Post Office Monitor Site Specifications AQS ID
Number Latitude Longitude Device Types Pollutants
Measured Address Scale Objective

04-023-

0004 31.3372 -110.936 Partisol
and BAM PM 10 , PM 2.5 , Meteorology 300 N. Morley

Ave Neighborhood Population

Source: State of Arizona Air Monitoring Network Plan for the Year 2011.

2.2 Air Quality Data

Monitoring for PM 10 began within the Nogales NA in 19 85. Since 1985, numerous exceedances
of the 24-hour PM 10 standard of 150 μ g/m 3 have been recorded, with 24-hour average ambient PM 10 values that exceed the standard ranging from 155 to 351 μ g/m 3 . Following the implementation of the control measures included in the 1993 Nogales NA SI P, a reduction was evident in both the maximum and second-highest 24-hour PM 10 concentrations. The Nogales NA met the PM 10 NAAQS by the

16 40 CFR Part 58, Appendices D and E.

17 Correspondence. Letter from EPA to ADEQ dated December 1, 2011. See Appendix F.1.

### 10 December 31, 1994, deadline established by the 1990 CAA Amendments (76 FR 1532; January 11, 2011). The Nogales NA continued to meet the NAAQS until 1998.

Since that time, intermittent exceedances have been recorded by the filter-based and continuously operating monitors. Although there were no exceedan ces recorded by the filter-based monitor in 2009- 2010, preliminary data indicate the filter monitor di d violate in 2011. The BAM monitor did record six exceedances in 2010; however, the BAM monitor expe rienced significant technical malfunctions during 2010 resulting in four calendar quarters with inco mplete data. Preliminar y data for 2011 indicate
exceedances were recorded. Quality assured and certified data for 2011 will be submitted to EPA in 2012.

Table 2.2 displays the maximum 24-hour values recorded by the filter-based PM 10 monitor from 1985-2010, and Table 2.3 displays the maximum 24-hour values recorded by the continuously operating
BAM monitor from 2005-2010. 18 Appendix H contains data for each quarter in the most recent three-year period during which quality-assured data is available, 2008-2010. To be in compliance with the NAAQS,
the area can not exceed the standard more than once per year on average over a 3 year period. For 2008- 2010, the Nogales NA did not meet the NAAQS (i.e., as show in Table 2.2, the rate of expected exceedances is greater than 1.)

Table 2.2 Nogales Filter-Based 24-hour PM 10 Monitoring Data 1985-2010

Year 24-hour
Max 24-hour
2 nd High 24-hour
3 rd High 24-hour
4 th High Percentage
of Valid
Observations Expected
Exceedances

1985 110 88 85 83 31 0

1986 162 152 126 124 64 5.75

1987 232 166 160 135 77 18.33

1988 155 147 143 133 74 8.36

1989 244 168 145 138 69 15.33

1990 175 108 107 106 85 8.36

1991 164 149 112 110 95 6.1

1992 153 146 134 101 87 0

1993 119 108 86 72 74 0

1994 116 95 91 72 85 0

1995 123 107 80 77 87 0

1996 104 88 92 88 69 0

1997 126 93 84 77 84 0

1998 169 158 116 90 82 13.5

1999 184 184 152 119 83 15.5

18 The Nogales continuously operating Beta Attenuatio n Monitor (BAM) experienced significant technical difficulties in 2010 that resulted in the invalidation of half the year’s monitoring data. The BAM was originally sited as a Special Purpose Monitor in 2005 that is now used to determine compliance with the PM 10 NAAQS.

### 11 Table 2.2 Nogales Filter-Based 24-hour PM 10 Monitoring Data 1985-2010

Year 24-hour
Max 24-hour
2 nd High 24-hour
3 rd High 24-hour
4 th High Percentage
of Valid
Observations Expected
Exceedances

2000 130 116 112 109 95 0

2001 213 112 96 95 93 6.9

2002 187 115 111 106 93 6.1

2003 184 162 125 119 100 12.3

2004 140 109 86 82 98 0

2005 279 205 156 144 97 17.93

2006 239 168 163 146 93 20

2007 190 133 122 115 97 6.1

2008 155 150 147 108 95 6.6

2009 123 116 109 105 95 0

2010 96 84 70 65 72 0 2008-2010 3-year Expected Annual Exceedances 2.2
Source: EPA’s Air Quality System database.

Table 2.3 Nogales Continuously Operating BAM Monitor

PM 10 Monitoring Data 2005-2010

Year 24-hour
Max 24-hour
2 nd High 24-hour
3 rd High 24-hour
4 th High Percentage of
Valid
Observations Expected
Exceedances

2005 351 327 324 306 80 29

2006 271 256 240 233 89 42

2007 233 211 210 210 98 14

2008 234 217 206 204 97 13

2009 238 204 147 146 94 2

2010 191 177 175 163 17* 8.49 2008-2010 3-year Expected Annual Exceedances 7.83
Source: Ibid. *2010 monitoring data doe s not meet completeness criteria.

Figure 2.1 illustrates the complete ambient PM 10 monitoring data history from 1985 through present for the filter monitor. This time period reflects ambient concentrations following the implementation of the control measures included in th e 1993 Nogales NA SIP. As the data shows, the Nogales NA met the NAAQS by 1994 and showed values below the sta ndard through 1998, after which

### 12 exceedances of the standard were recorded. Since 1998, only 2000 and 2004 provided years with no observed exceedances of the NAAQS.

Figure 2-1 Nogales Post Office Filter-Based PM 10 Monitoring Data Trends 1985-2010

0 50 100 150 200 250 300

1 9 8 5

1 9 8 6

1 9 8 7

1 9 8 8

1 9 8 9

1 9 9 0

1 9 9 1

1 9 9 2

1 9 9 3

1 9 9 4

1 9 9 5

1 9 9 6

1 9 9 7

1 9 9 8

1 9 9 9

2 0 0 0

2 0 0 1
2 0 0 2

2 0 0 3

2 0 0 4

2 0 0 5

2 0 0 6

2 0 0 7

2 0 0 8

2 0 0 9

2 0 1 0ug/m3

24hr Max 2nd 24hr High PM10 NAAQS PM 10 NAAQS

Source: EPA's AQS Database.

Figure 2-2 Nogales BAM Monitoring Data Trends 2005-2010

0 50 100 150 200 250 300 350 400

2005 2006 2007 2008 2009 2010ug/m3

1st Hi 2nd Hi 3rd Hi 4th Hi PM10 NAAQS

Source: Ibid.

2.3 24-hour PM 10 NAAQS Compliance

The primary (health) and secondary (welfare) 24-hour PM 10 standards are met when the expected number of exceedances per year at each monitoring site is less than or equal to one. The expected number of exceedances per year is determined by recordi ng the number of exceedances in each calendar year and averaging them over the past three years. Based on complete quality-assured data for 2008-2010, the number of expected exceedances of the 24-hour PM 10 NAAQS for the Nogales NA is 2.2 for the filterbased monitor and 7.9 for the BAM monitor. Because th e annual expected exceedance rate is greater than 1.0, the Nogales NA is not currently meeting the PM 10 standard.

### 13 3.0 EMISSIONS INVENTORY

This chapter discusses the development of the emissions inventory required by the CAA Section 172(c)(3). The 2008 emissions inventory for the Nogales NA 19 was developed starting with the 2008 National Emissions Inventory (NEI) for Santa Cruz County. Then, county-level emissions estimates were apportioned to the Nogales NA based on populati on and land ratios, or actual location in the case of a stationary source. Figure 3.1 illustrates the majo r source categories in the Nogales NA in 2008

.

Figure 3.1 2008 Annual Emissions Inventory for the Nogales, Arizona
PM 10 Nonattainment Area 1,531 tons per year total

Other 87 tpy

6% Residential Garbage Burning 24 tpy

2% Residential Construction 24 tpy

2% Residential Wood Burning 24 tpy

2%

Paved Road Dust 121 tpy

8%

Commercial/

Industrial Construction 143 tpy
9% Road Construction 267 tpy

17% Unpaved Road
Dust 865 tpy

57%

Source: 2008 and 2011 PM 10 Emissions Inventories for the No gales NA, Santa Cruz County, Arizona (see Appendix B). Estimates are rounded.

3.1 Significant Emissions Sources

The annual PM 10 emissions inventory for the Nogales NA in 2008 is 1,531 tons per year (tpy). The four largest source categories comprise 90 percent of emissions generated in the Nogales NA. Those categories are fugitive dust from unpaved and paved roads, and dust generated by road and building construction.

The greatest source of emissions in the nonatta inment area is fugitive dust from unpaved roads, accounting for 57 percent of annual emissions and 865 tpy. The 2008 emissions inventory determined
that emissions from Road Construction are the second greatest source of PM 10 emissions in the Nogales NA, accounting for 18 percent of annual emissions and 267 tpy. Fugitive emissions from Commercial

19 The more detailed 2008 and 2011 PM 10 Emissions Inventories for the Nogales Nonattainment Area, Santa Cruz County, Arizona are found in Appendix B of this plan.

### 14 and Industrial sources are the third greatest source of PM 10 emissions in the nonattainment area, accounting for nine percent of annual emissions a nd 143 tpy. Control measures for this source are discussed in Section 4.0. The fourth greatest source of PM 10 emissions in the Nogales NA is dust from paved roads. Emissions for this category total eight pe rcent of the 2008 emissions inventory and 121 tpy.

In total, the four emissions source catego ries discussed above account for 90 percent of
annual emissions in the nonattai nment area and 1,396 tons per year; see Table 3.1. The RACM implemented for these significant source categories an d others are discussed in detail in Section 5.0.

Table 3.1 Significant PM 10 Emissions Sources in the Nogales NA, 2008

PM 10 Source Categories TPY Percentage of
Annual Emissions
Fugitive Dust from Unpaved Roads 865 57
Road Construction Dust 267 18
Commercial and Industrial Construction Dust 143 9
Paved Road Dust 121 8 Total 1,396 90

Source: 2008 PM 10 Emissions Inventory for the Nogales NA (see Appendix B). Estimates are rounded.

Residential construction, and residential wood and waste burning, each account for 2 percent of the 2008 annual emissions inventory. Those source categories are below the de minimis threshold, and therefore control measures are not required. Simila rly, ADEQ determined
that the emissions sources shown in Table 3.2 did not significantly contribute to ambient PM 10 concentrations in the Nogales NA; therefore, control measures were not developed for these categories, which collectively account for three percent of the 2008 emissions inventory. The remaining minor source categories which contribute less than 2 tons of PM 10 per year are included in Appendix B.

Table 3.2

PM 10 Emissions Sources in the Nogales NA, 2008

PM 10 Source Categories TPY
Onroad Mobile - Diesel (includes exhaust, brake and tire wear) 19 Onroad Mobile - Gasoline (include s exhaust, brake and tire wear) 8 Commercial Cooking – Charbroiling 6 Agriculture/Livestock Dust 4
Prescribed Fires 3 Non-road Gasoline Equipment 3
Aircraft 2

Total 45

Source: Ibid. Estimates are rounded.

### 15 3.2 Nogales NA Future Year (2011) PM 10 Emissions Projections

Projected emissions for 2011, shown in Tabl e 3.3, were developed based on projected growth rates for population, industry, and motor vehicle activity for the Nogales NA. Motor vehicle emissions for 2011 are slightly lower th an 2008 due to a newer cleaner fleet of vehicles and implementation of new fuel standards. The Federal Highway Administration's Highway
Statistics statewide series data on Arizona shows a decline in Vehicle Miles Traveled (VMT) between 2007 and 2008, and no change in VMT between 2008 and 2009. This trend is consistent with
economic conditions. As discussed in Section 1.0, population and economic growth is not expected between 2008 and 2011 due to current economic conditions. Accordingly, no increases in source categories affected by these factors are projected. The complete projected inventory and methodology for emissions projections are included in Appendix B.

Table 3.3 Projected PM 10 Emissions 2008 and 2011 (tons per year)

Emissions Source Category 2008 tpy 2011 tpy Projection
Method Dust - Unpaved Road Dust 864.9 864.9 No growth Dust - Road Construction 267.0 267.0 No growth Dust - Commercial/Industrial/Institutional Construction 142.6 142.6 No growth Dust - Paved Road Dust 121.4 121.4 No growth Fuel Comb - Residential - Wood 24.0 25.7 Population Waste Disposal - Residential Garbage Burning 23.0 24.7 Population Dust - Residential Construction 23.9 23.9 No growth Mobile - Onroad Diesel (includes brake, tire, and exhaust) 19.4 13.2 Lower Emissions/MOVES Mobile - Non-Road Equipment - Diesel 8.5 8.5 No growth Mobile - Onroad Gasoline (includes brake, tire, and exhaust) 8.4 7.9 Lower Emissions/MOVES Commercial Cooking - Charbroiling 6.3 6.7 Population Fires - Prescribed Fires 3.4 3.4 No growth Agriculture - Crops & Livestock Dust 4.3 4.3 No growth Mobile - Non-Road Equipment - Gasoline 3.1 3.1 No growth Mobile - Aircraft 2.3 2.3 No growth Other (see Appendix B) 8.2 8.5 Various
TOTALS 1530.7 1528.2

Source: 2011 PM 10 Emissions Inventory for the Nogales NA, Santa Cruz County, Arizona (see Appendix B). Estimates are rounded.

### 16 4.0 Demonstration of Attainment in Accordance with Section 179B of the CAA

Section 179B of the Clean Air Act allows a St ate to demonstrate that exceedances of the PM 10 NAAQS in the Nogales NA would not occur were it not for PM 10 emissions from Nogales Municipality, Sonora, Mexico. In this section, the relevant data and observations taken from the following supporting analyses are reviewed:

 Clean Air Act, Section 179B Attainment Determination for the Nogales, Arizona PM 10 Nonattainment Area;

 2008 and 2011 Emissions Inventories for the Nogales NA;

 2008 and 2011 Emissions Inventories for the N ogales Municipality, Sonora, Mexico; and,

 Analysis of Ambient PM 10 Levels, Topography, and Meteorologi cal Data in Nogales, Arizona:
2007-2009.

This section provides a summary of these supporting anal yses for this determinatio n of attainment of the

PM 10 NAAQS, but for international emissions. These four analyses are provided in full and can be found in Appendices A through D of this Nogales Plan. 20

Consistent with 40 CFR Part 50, appendix K, the standard used to determine attainment of the PM 10 NAAQS in the Nogales NA, “but for” international emis sions is as follows: the expected number of days per calendar year with a twenty-four hour average concentration above 150 μ g/m3 must be equal to or less than one. Consequently, to determine that the Nogales NA has met the PM 10 standard “but for” emissions from Mexico, the State must show through this analysis that no more than three exceedances (based on data completeness and every day sampling) over a three year period were due to emissi on sources arising within the Nogales NA, and that all other monitored exceedances of the NAAQS originate from Mexico.

4.1 Population Growth in Nogales, Sonora

Population estimates provide an indication of anthropogenic PM 10 emissions sources on both
sides of the international border. The combined area of Nogales, Arizona, and the Nogales Municipality, Sonora, Mexico, is collectively known as Ambos N ogales. The Nogales Municipality, Sonora, Mexico

20 The document “Clean Air Act, Section 179B Attain ment Determination for the Nogales, Arizona PM 10 Nonattainment Area” includes “2008 and 2011 Emissions Inventories for the Nogales NA”, “2008 and 2011 Emissions Inventories for the Nogales Municipality, Sonora, Mexico”, and “Analysis of Ambient PM 10 Levels, Topography, and Meteorological Data in Nogales, Arizona: 2007-2009” as supporting appendices A through C; therefore, all four analyses should be considered one docum ent and when reading them one should keep in mind that they reference each other. For ease of reference within this Noga les plan, however, these four documents have been split apart, are provided each with their individual appendix, and are cited as such herein. To avoid confusion, please keep in mind this
difference as a frame of reference.

### 17 accounts for 90.2 percent of the 2010 population in the Ambos Nogales area. 21 Figure 4.1, below, depicts the rapid/regular population growth of the Nogales Municipality, Sonora, and the consistently low or no population growth of Nogales, Arizona.



### Figure 4.1 Comparison of Ambos Nogales Population Growth 1995-2010

0 50 100 150 200 250Thousands

Nogales Municipality, Sonora 133,491 159,787 193,517 220,292

Nogales, Arizona 20,184 20,878 20,421 20,837 1995 2000 2005 2010



### 4.2 Nogales, Sonora Em issions Inventories

The 2008 and 2011 Nogales Municipality, Sonora em issions inventories shown in Table 4.1 were
derived from Mexico's 1999 National Em issions Inventory, using a methodol ogy explained in detail within Appendix C. The Nogales, Sonora emissions inventorie s contain low and high estimates for point sources and paved and unpaved roads due to the re lative uncertainty of scaling or calculating these estimates. Point source estimates are presented as a range because different calculation methods produ ced a difference in results. Paved and unpaved road estimates are presented as a range given the range of sample data used to calculate these source categories. Again, the methods and data used to deve lop these emissions estimates ca n be found in Appendix C. In both high and low inventories, fugitive emissions fro m paved and unpaved roads were identified as the greatest
sources of the ambient PM 10 concentrations in Nogales, Sonora. See Table 4.1.

21 Table 1, "Clean Air Act, Sec tion 179B Attainment Determinatio n for the Nogales, Arizona PM 10 Nonattainment Area” (see Appendix A).

### 18 Table 4.1.

2008 and 2011 PM 10 Emissions Inventories for Nogales Municipality, Sonora (tpy) 22 Source Category Range 2008 2011

Point Sources Low Estimate 1.1 1.1 High Estimate 305 390 Area Sources Unpaved Roads Low Estimate 2,144 2,308 High Estimate 5,521 5,944
Paved Roads Low Estimate 53 57 High Estimate 646 696 Agricultural Tilling 0.8 0.8 Agricultural Burning 1.6 1.6
Residential Wood Combustion 176 47 Open Burning of Waste 55 56
Construction Activities 23 24 Remaining Area Sources 159 150
Mobile Sources 80 85
Nonroad Sources 20 27

Total Low Estimate 2,713 2,757

Total High Estimate 6,987 7,420

22 Emissions are rounded to the nearest ton/year , or to the nearest tenth of a ton/year for emissions le ss than ten tons/year. Sou rce: "2008 and 2011 PM 10 Emissions Inventories, Nogales M unicipality, State of Sonora, Mexi co", March 2012. (See Appendix C).

### 19 4.3 Comparison of Ambos Nogales Emissions Inventories

Nogales NA, Arizona and Nogales Municipa lity, Sonora have similar sources of PM 10 , primarily fugitive dust from unpaved and paved roads, as well as combustion sources and construction. A comparison of the Nogales, Sonora 2008 low emission inventory and the 2008 Nogales NA inventory concludes that there is a 64/36 percent split in total Ambos Noga les emissions between em issions from Sonora and Arizona; a comparison of the 2008 high emission invent ory suggests that there is an 82/18 percent split
between emissions from Sonora and Ar izona. Figure 4.2 depicts the emis sions split. A di fferent metric comparing the emissions inventory data shows that for every one ton of PM 10 produced in the Nogales NA,
there were between 1. 8 and 4.6 tons of PM 10 emissions produced annually in the Nogales Municipality.

1531 6988

1531 2757

0 1000 2000 3000 4000 5000 6000 7000

PM 10 TPY

High Inventory Low Inventory Figure 4.2 Nogales, Sonora 2008 High and Low Inventories Compared to Nogales NA 2008 Inventory

Nogales NA Emissions Nogales Municipality, Sonora Emissions

Source: Appendices B and C.

4.4 PM 10 Exceedance Analyses – Ambient Monitoring Data, Wind Speed, and Temperature Changes

For these analyses, ambient monitoring data from 2007-2009 collected by the by the continuously operating Beta Attenuation Monitor (BAM) monitor w as examined; data collected by the BAM in 2010 did not meet CAA completeness criteria, and 2011 data wa s not compiled and certified at the time of this analysis. Over the 2007-2009 timeframe, 29 exceedances of the NAAQS were recorded by the BAM at the Nogales, Arizona Post Office. 23 Data recorded by the BAM mon itor was selected for the analysis because the monitor recorded the greatest number of exceedances at the monito ring site and records hourly ambient PM 10 values. The meteorological monitor at the site also provides hourly wind speed and direction data. The majority of the 29 exceedance days in our 2007 to 2009 study timeframe, 23 exceedances (or 79 percent), occurred during October to January, mostly in November. See Figure 4.3.

23 Arizona has not flagged any of these 2007 through 2009 exceedan ce days for potential exclusion from air quality planning considerations under EPA’s Exceptional Events Rule.

### 20 Figure 4.3

PM 10 Exceedances at the Nogales, Arizona Post Office, by Month and Year

Source: EPA AQS database.

Analysis of ambient air quality data identified 26 of the 29 exceedances as having nearly identical hourly emission, wind speed and temperature profiles. As shown in Figures 4.4 and 4.5, the exceedance days began with a repeated pattern of declining PM 10 concentrations in the early morning hours followed by a pronounced increase starting at 6:00 am a nd a decline around 9:00 a.m. Figures 4.6 and 4.7 demonstrate that wind speeds and temperatures rise, dispersing the spike in morning PM 10 concentrations. As the day progresses, ambient PM 10 concentrations reach their lowest points between 10:00 am and 4:00 pm. As temperatures drop by as much as 20 degrees Fahrenheit over 3 to 4 hours and wind speeds drop through the evening, a spike in PM 10 concentrations between 4:00 pm and 6:00 pm is observed that may correspond with evening commute hours. Ambient concen trations remain high for several hours through the evening, before eventually declining around 10:00 pm.

### 21 Figure 4.4 Hourly Ambient PM 10 Concentrations on 29 Exceedance Days

Source: "Analysis of Ambient PM 10 Levels, Topography, and Meteorological Data in Nogale s, Arizona: 2007-2009" (see Appendix D)

### 22 Figure 4.5 Hourly Ambient PM 10 Concentrations on 26 Similar Exceedance Days, Excluding the Following Days: January 1, 2007; May 22, 2008; and January 1, 2009

Source: Ibid.

### 23 Figure 4.6: Hourly Wind Speed Variations on 29 Exceedance Days

Source: Ibid

.

### 24 Figure 4.7: Hourly Temperature Variations on 29 Exceedance Days

Source: Ibid.

4.5 Wind Direction and Pollution Rose Analyses

Wind roses were used to depict wind direction and speed on exceedance dates in Ambos Nogales. Wind roses depict hourly wind direction and wind speed values collected over 24 hours; the wind data is then sorted by direction so that the percentage of time that the wind was blowing from each direction can be determined. Wind speed data is then superimpos ed on each of the wind rose's twelve 30o segments to illustrate the average wind speed when the wind was bl owing from that segment's direction. Figure 4.8 depicts the wind speeds and directions for all of the 29 PM 10 exceedances analyzed. A clear pattern of winds from a southerly direction traveling at low speeds emerges on exceedance days.

### 25 Figure 4.8 Wind Rose of Wind Speed vs. Wind Direction at the Nogales, Arizona Post Office BAM Monitor for all 29 Exceedance Days

Source: Appendix D - Analysis of Ambient PM 10 Levels, Topography, and Meteorological Data in Nogales, Arizona: 2007-2009

Pollution rose analyses substitute ambient hourly PM 10 values for wind speed to provide a depiction of wind direction and correlated ambient c oncentrations. The result is a graphical representation of the possible directionality of pollution sources and the ambient concentration levels time-linked with those wind direction observations. See Figure 4.9. A review of the hourly ambient data shows that on exceedance days, 71-92 percent of hourly values exceeding 150  g/m 3 and 92 percent of the highest

### 26 observed PM 10 concentrations (above 450  g/m 3 ), are associated with a southerly wind direction (135-225 degrees). 24 Appendix D includes additional wind and pollutio n rose analyses.

Figure 4.9
Pollution Rose of PM 10 Concentration vs. Wind Direction at the Nogales, Arizona Post Office BAM for all 29 Exceedance Days

Source: Appendix D - Analysis of Ambient PM 10 Levels, Topography, and Meteorological Data in Nogales, Arizona: 2007-2009.

24 See Table 11 in "Clean Air Act, Section 179B Atta inment Determination for the Nogales, Arizona PM 10 Nonattainment Area” (see Appendix A). Section 3.3.1 of that docume nt provides additional analyses of ambient PM 10 values and wind direction.

### 27 4.6 A Conceptual Model of 2007-2009 Exceedance Days

As described in Section 4.4, 26 of the 29 2 007 - 2009 exceedances showed a similar pattern of
ambient PM 10 concentration, wind speeds, wi nd direction, and temperature va riation over a twenty-four hour period. The three exceptions were th e January 1, 2007, May 22, 2008, and January 1, 2009 exceedance days. Two of these days, January 1, 2007 and January 1, 2009, wi th higher early morning PM 10 concentrations, only vary slightly from the diurnal profile of PM 10 concentrations observed for the other exceedances, but these two days have similar meteorological and concentration patterns throughout the rest of the day. Also, two of the 29 exceedance days, January 1, 2007, and January 26, 2008, showed high aver age ambient concentrations during
hours when the wind was from directions other than the southerly 90 degree qu adrant (135-224 degrees on a compass). Thus, there are twenty-five exceedance days that are equivalent and can be considered here as a group, setting aside the dissimilar exceedance days liste d above, January 1, 2007, January 26, 2008, May 22, 2008, and January 1, 2009. These re maining 25 similar exceedance days provide the basis for a daily conceptual model consistent with ambient concentratio ns, wind speed and direction, temperature changes, diurnal heating and cooling pa ttern, and relative pollution loads discussed in sections 4.2, 4.3, and 4.4 above. See Figure 4.10.

### 28 Figure 4.10 Average Hourly PM 10 Concentration, Wind Speed, and Temperatur e at the Nogales, Arizona Post Office BAM vs. Time of Day for all Exceedances Excluding Jan uary 1, 2007, May 22, 20 08, and January 1, 2009 25

Source: Ibid.

To review the conceptual model and average PM 10 concentration, wind speed, and temperature profiles in Figure 4.10, beginning at midnight and through the early morning hours, there is a strong pattern of decreasing PM 10 concentrations from the previous day’ s high values. Then, in the morning hours, there is a pronounced PM 10 increase and drop-off between 6:00 am and 9:00 am, suggesting an almost daily reproducible PM 10 source, such as fugitive road dust from the morning commute. As morning temperatures rise, so does wind speed and wind direction changes from south to north dispersing the morning spike in PM 10 concentrations. PM 10 concentrations continue to fall through the afternoon and reach their lowest points between 10:00 am and 4:00 pm. The morning and afternoon increases in ambient temperature and wind speed can be attributed to the he ating portion of a diurnal heating and cooling cycle where heated air flows from lower elevations to the north to the higher elevations to the south.

25 The diurnal pattern shown in Figure 4.10 applies to 25 very simi lar exceedance days and also includes January 26, 2008 given this day’s similar diurnal profile. Elem ents of the conceptual model discussion, however, may not apply to January 26, 2008 because of the higher observed PM 10 concentrations when winds were from the ea st southeast and outside of the 90 degree southerly wind direction quadrant. For th is reason, the January 26, 2008 exceedance day was examined in further detail along
with the other three exceedan ce days, January 1, 2007, May 22, 2008, and January 1, 2009.

### 29 As evening approaches and night falls, the diurnal cooling cycle begins as ambient temperatures drop and lower elevation air masses no longer rise with conv ection causing wind speed to drop and wind direction to vary. As temperatures continue into the night, wi nd speeds drop and cold air masses flow down from higher elevations in Nogales, Sonora causing wind direction to shift from a variable/northerly direction to a southerly direction. A corresponding and pronounced spike in PM 10 concentration is observed beginning between 4:00 pm and 6:00 pm, again suggesting an almost daily reproducible PM 10 source, such as fugitive road dust from the evening commute. Concentrations remain high for several more hours into the night and gradually begin to decrease as midnight appr oaches. The highest concentrations of PM 10 occur in these evening hours when dust from vehicle traffic on unpaved and paved roads may be captured by cold air flows from higher elevations and moving south to north. Also, home heating combustion may be part of the evening PM 10 load and is captured in the evening northerly air flows.

Usually, this pattern of exceedan ces is observed during times when the general weather pattern allows for stagnation and a relatively still air mass subject to movement by the diurnal cooling and heating cycle. At other times of the year, frontal weather systems move through often enough and with enough energy to prevent a stagnant air mass and the diurnal h eating and cooling cycle from exerti ng a strong influence on the local meteorology and from causing exceedances of the PM 10 standard.

It should be noted that this conceptual model is consistent with the study by Arizona State University,

“ Atmospheric, Hydroclimatic, and An thropogenic Causes of Fugitive Dust in the Nogales, Arizona-Nogales,
Sonora Airshed .” 26 In this study, the authors co nclude that stagnant atmospheric conditions over a large scale are the most important factor in predicting high daily PM 10 concentrations in the Ambos Nogales area.

Finally, for these similar 25 days, the ambient concen tration attributed to the southerly wind direction quadrant (90 degrees) always exceeds the 150 μ g/m 3 level, in most cases markedly . Conversely, the ambient
concentration attributed to the all other wind direct ion quadrants (the remaining 270 degrees) never exceeds
the 150 μ g/m 3 level. Across all 25 exceedance days, the average concentration value for the southerly wind direction quadrant concentration is 264 μ g/m 3 , with the range for each day’s average concentration being 163
to 369 μ g/m 3 . In comparison, the average concentration valu e across these 25 exceedance days for the all other wind direction quadrants is 80 μ g/m 3 , with the range for each da y’s average being 38 to 148 μ g/m 3

. 27

4.7. Review of Exceedance Days Diff ering From 25-Day Conceptual Model

As described in Section 4.6, the data support th e finding that at least 25 of 29 exceedances of the

PM 10 standard in the Nogales NA can be attributed to sources of PM 10 originated from across the international border. There are, however, four exceedance days that differ in one or more ways from the conceptual model of PM 10 exceedances in the Nogales NA: Ja nuary 1, 2007; May 22, 2008; January 26, 2008; and January 1, 2009.

26 Completed in 2002 by A.W. Ellis, the final report is availa ble through The Southwest Center for Environmental Research and Policy at http://scerpfiles.org/con t_mgt/doc_files/A-02-2.pdf

. 27 See Table 12 of Appendix A for average hourly concentrations segregated into those attributed to the southerly wind quadrant and the 270 degree all other wind direc tion quadrant for all exceedance days.

### 30 January 1, 2007 and January 1, 2009 had a diurnal pattern that varied from the conceptual model and further analysis showed a higher PM 2.5 component compared to the remaining 27 exceedance days, suggesting a larger contribution from combus tion sources such as residential wood burning. 28 See Figures 4.11 and Figure 4.12.

Figure 4.11 January 1, 2007 PM 10 Concentrations and Wind Speeds Compared to 26 Exceedance Day Average PM 10 Concentrations and Wind Speeds from Figure 4.10

Source: Appendix D - Analysis of Ambient PM 10 Levels, Topography, and Meteorological Data in Nogales, Arizona: 2007-2009.

28 See Section 4.4, of Appendix D for discussion of PM 2.5 concentrations relative to PM 10 concentrations for the 29 exceedance days.

### 31 Figure 4.12 January 1, 2009 PM 10 Concentrations and Wind Speeds Compared to 26 Exceedance Day Average PM 10 Concentrations and Wind Speeds from Figure 4.10

Source: Ibid.

The May 22, 2008 exceedance is associated with high winds. Most of the highest hourly concentrations in the 29 exceedance days occurred on May 22, 2008. The PM coarse component on this day was higher compared to the remaining 28 ex ceedance days suggesting a large contribution from fugitive dust sources such as open ar ea, and unpaved a nd paved roads. 29 Furthermore, all wind direction observations were southerly. See Figure 4.13 below.

29 See Section 4.4 of Appendix D for discussion of PM 2.5 concentrations relative to PM 10 concentrations for the 29 exceedance days.

### 32 Figure 4.13 May 22, 2008 PM 10 Concentrations and Wind Speeds Compared to 26 Exceedance Day Average PM 10 Concentrations and Wind Speeds from Figure 4.10

Source: Appendix D - Analysis of Ambient PM 10 Levels, Topography, and Meteorological Data in Nogales, Arizona: 2007-2009.

As described earlier, January 26, 2008 has a si milar diurnal pattern to the 25-day conceptual model. See Figure 4.14. Other elements of the con ceptual model, however, may not apply to January 26, 2008 because of the higher observed PM 10 concentrations when winds were from the east-southeast and outside of the 90-degree southerly wind direction quadr ant. This results in high average concentrations for all the other wind direction quadrants. See Table 4.2 below.

Figure 4.14 January 26, 2008 PM 10 Concentrations and Wind Speed Compared

Average PM 10 Concentrations and Wind Speeds from Figure 4.10

Source: Ibid.

### 33 In addition to diurnal patterns, high concentrations from the “all other wind direction” quadrants were examined for these four exceedance days. On all 29 exceedance days, the ambient PM 10 concentration attributed to the southerly wind quadrants exceeds 150 μg/m 3 . In contrast, two exceedance days from the “all other wind direction” quadrants show a value greater than 150 μg/m 3 : January 1, 2007 and January 26, 2008. Only one of 29 exceedance days shows the concentration attributed to the “all other wind direction” quadrant greater than that of the concentration attributed to the southerly wind quadrant: January 1, 2007. See Table 4.2.

Table 4.2 24-hour Concentration and Hourly Concentratio ns Disaggregated by Southerly Wind Direction Quadrant for Exceedance Days Differing from Conceptual Model

Date 24-hour PM 10 Concentration (μg/m 3 ) Southerly Wind Quadrant

PM 10 Average Concentration (μg/m 3 ) (135 to 224 degrees) All Other Wind Direction

PM 10 Average Concentration (μg/m 3 ) (225 to 134 degrees) January 1, 2007 210 199 (15 of 24 values) 231 (9 of 24 values) January 26, 2008 204 257 (7 of 24 values) 182 (17 of 24 values) May 22, 2008 217 217 (24 of 24 values) No Observed Values January 1, 2009 238 323 (14 of 24 values) 119 (10 of 24 values) Source: Air Quality System database.

4.8 Expected Exceedance Days “But For” International Transport from Mexico

Consistent with 40 CFR Part 50, appendix K, the standard used to determine attainment of the

PM 10 NAAQS in the Nogales NA, “but for” international emissions is as follows: the expected number of days per calendar year with a twenty-four hour average concentration above 150 μ g/m 3 must be equal to or less than one. Consequently, to dete rmine that the Nogales NA has met the PM 10 standard “but for” emissions from Mexico, this analysis must show that no more than three exceedances (based on data completeness and every day sampling) in the 2007-2009 analysis period were due to emission sources arising within the Nogales NA, and that all othe r monitored exceedances of the NAAQS originate from Mexico. Two analyses were used to examine the i ssue of expected exceedances but for international emissions: a daily analysis reviewing selected exce edance days; and, an analysis of observed hourly concentrations designed to estimate a Nogales NA 24-hour average concentration after accounting for the
influence of international emissions.

4.8.1 Daily Analysis of Expected Exceedances

From the day-by-day review above, it is possible to determine whether or not to assign the four exceedance days in question, January 1, 2007, Janua ry 26, 2008, May 22, 2008, and January 1, 2009 to the category of exceedance days having a significan t contribution from sources on the Nogales, Sonora
side of the international border.

The May 22, 2008 exceedance day is completely di fferent from the conceptual model exceedance day because of the relative high wind speeds and highe r than usual coarse PM (e.g., unpaved roads) component. As with total PM 10 emissions, emissions of coarse PM are higher from Nogales, Sonora, than

### 34 they are from the Nogales NA. The wind direction is from a southerly quadrant in all hourly
concentration observations. Given this informatio n, this day should be placed with the 25 other exceedance days in the conceptual model, because it is likely that the sources of PM 10 causing the exceedance originated from the Nogales, S onora side of the international border.

The January 1, 2009 exceedance day is different from the conceptual model exceedance day in the timing and distribution of observed ambient PM 10 values and high PM 2.5 component most likely caused by a combustion source. As with total PM 10 emissions, emissions of fine PM (e.g., combustion sources) are higher from Nogales, Sonora, than they are from the Nogales NA. The key factor for assigning this day is the contribution of high hourl y ambient concentrations with a southerly wind direction quadrant compared to the remaining 270 de gree wind direction quadrants (see Table 4.2 above). Consequently, this day should be placed with the 25 other exceedance days in the conceptual model, because it is likely that the sources of PM 10 causing the exceedance originated from the Nogales, Sonora
side of the international border.

Considering the January 1, 2007 exceedance day, it also differs from the conceptual model exceedance day in the timing and distribution of observed ambient PM 10 values and high PM 2.5 component. What differs in the case of the Janua ry 1, 2007 exceedance is that the 270 degree wind direction quadrants contains enough high values to c ontribute disproportionately to the overall twentyfour hour average concentration (see Table 4.2). A lthough more detailed and di fferent field studies might prove otherwise, with the information available, th is analysis is inconclusive as to whether this exceedance can be attributed solely to a disproportion ate international contribution from Nogales, Sonora.

Finally, the January 26, 2008 exceedance day is most like the conceptual model exceedance day in the timing and distribution of observed ambient PM 10 values. While the southerly wind direction quadrant contains enough high values to contribute disproportionately to the overall twenty-four hour average concentration, there are enough remaining hi gh values in the 17 of 24 hourly observations from the 270 degree wind direction quadrants to be above the 150 μg/m 3 level (see Table 4.2). Again, while specifically designed field studies might help determine the relative contributions to this exceedance, with the information available, this analysis is inconclu sive as to whether this exceedance can be attributed solely to a disproportionate internationa l contribution from Nogales, Sonora.

To summarize, two exceedance days, May 22, 2008 and January 1, 2009, should be categorized with the 25 exceedance days where there is a high likelihood of a large contribution of PM 10 from sources on the Nogales, Sonora side of the international bor der across from the Nogales NA. The two remaining exceedance days, January 1, 2007 and January 26, 2008, may have a contribution from sources on the Nogales NA side of the international border such th at one cannot say whether there is a high likelihood
that the area would not have exceeded the PM 10 standard but for PM 10 emissions originating from the Nogales, Sonora side of the international border.

### 35 4.8.2 Hourly Analysis of Expected Exceedances

In this analysis, each hourly concentration valu e from the 29 exceedance days was classified based on the likely influence from Mexico according to four criteria or decision rules. An hourly concentration value that was classified by a given decision rule was then weighted by 0.36, representing the maximum proportion of Nogales NA emissions compared to the total Ambos Noga les regional emissions and e quivalent to assuming a 36 percent contribution from U.S. sources during those hours. 30 Then, a 24-hour average concentration was
recalculated to determine what concentration would have occurred but for international transport of PM 10 emissions from Nogales, Sonora.

To review the decision rules for classifying the hourly values per Mexican influence, the first decision rule identified periods consistent with su stained high winds from the south carrying wind-blown dust, as discussed earlier concerning the May 22, 2008 exceedance day. The second and third decision rules identified daily periods influe nced by downslope wind flow conditions usually occurring in the late afternoon and evening, indicative of sustained downsl ope air flows from higher elevations south of the
international border. The fourth decision rule identi fied periods of sustained air mass stagnation usually found in the late night and early morning hours after the early evening downslope wind or air flow has ebbed and before sunrise, after which wind speeds be gin to increase from their overnight low values.

To show the effects of each decision rule, an estimated 24-hour concentrat ion was calculated after the application of Rule 1, Rules 2 and 3, Rules 1- 3, and Rules 1-4. The results are summarized below. 31

 The application of Rule 1 only removes one da y, May 22, 2008; leaving 28 days showing a concentration value greater than 150 μg/m 3

.

 The application of Rules 2 and 3 removes 27 da ys; leaving January 1, 2007 and January 26, 2008 showing a concentration value greater than 150 μg/m 3 ; 196.8 μg/m 3 and 244.1 μg/m 3 , respectively.

 The application of Rules 1, 2, and 3 again removes 27 days; leaving January 1, 2007 and January 26, 2008 showing a concentration value greater than 150 μg/m 3 ; 196.1 μg/m 3 and 244.1 μg/m 3

, respectively.

 The application of Rules 1, 2, 3, and 4 removes 29 days; leaving no estimated days with a value greater than 150 μg/m 3

.

In conclusion, this analysis of hourly concentr ation values, demonstrates that at least 27 of 29, and possibly all 29 exceedances of the PM 10 NAAQS observed in the Nogales NA during 2007 - 2009 can
be attributed to sources of PM 10 from across the international border.

30 See the emission inventory comparisons of the Noga les NA and the Nogales Muni cipality in Section 4.3.

31 See Section 3.7 of Appendix D “Analysis of Ambient PM 10 Levels, Topography, and Meteor ological Data in Nogales, Arizona: 2007-2009” for a complete discussion of the de cision rules and all estimated 24-hour concentrations.

### 36 4.9 Conclusion

A nonattainment area meets the national am bient air quality standard (NAAQS) for PM 10 when the expected number of days per calendar year with a twenty-four hour average concentration above 150 μg/m 3 are less than or equal to one. To determine that the Nogales NA has met the PM 10 standard “but for” emissions from Mexico, this analysis must show that no more than three exceedances of the standard in the 2007-2009 analysis period we re due to sources within the Nogales NA and all other exceedances were caused by sources originating from across the intern ational border. This analysis found that 27 of 29 exceedance days were due to transport of PM 10 emissions from sources on the Nogales, Sonora side of the international border. Consequen tly, when considering a maximum of two remaining exceedances, the expected annual exceedance rate for 2007-2009 is 0. 7 exceedances per year. Since the annual expected exceedance rate is less than one, the State has demo nstrated that the Nogales NA would attain the PM 10 NAAQS “but for” PM 10 emissions originating in Mexico.

### 37 5.0 CONTROL MEASURES

This section discusses the selection, implementation, and results of reasonably available control measures (RACM) and technology (RACT) implemen ted in the Nogales Nonattainment Area (NA).

The Arizona Administrative Code (AAC) rules already approved in the State SIP and relied upon for this plan are listed in Table 5.1.

5.1 Definition and Selection of RACM/RACT

EPA defines RACM/RACT as measures that a State finds are both reasonably available and
contribute to attainment as expeditiously as practicable. When developing a SIP for a moderate PM 10 nonattainment area, the State is requ ired to provide an analysis identifying which of EPA’s RACM and RACT are appropriate for controlling significant PM 10 sources. The State is instructed to begin with EPA’s suggested RACM and RACT for fugitive dust, prescr ibed burning, and residential wood burning (57 FR 13540; April 16, 1992). The CAA also dire cts the State to consider potenti al control measures proposed by the local community during the public comment period as well as RACM in other similar areas. The RACM selected by the State must provide emissions controls for sources identi fied in the emissions inventory as significant sources of PM 10 emissions. RACM are not required for in significant sources, controlled sources
where additional measures would not ex pedite attainment of the NAAQS, or for sources not present in the
nonattainment area.

The emissions inventory in the 1993 Nogales NA SIP and the 2008 emissions inventory in Section 3.0 cited the same significant PM 10 emissions source categories for the Nogales NA. Accordingly, ADEQ is evaluating the implementation of co ntrol measures from the 1993 Nogale s NA SIP within this plan.

32 R18-2-702, General Provisions, reflects the current R18 Arizon a Administrative Code numbering format. The R9 series of rules were subsequently renumbered as well, but have only been approved by EPA in the original numbering format. Table 5-1 Arizona Administrative Code Rules Approved into the Arizona SIP for PM 10 Sources

Rule FR Date FR Citation R9-3-404 Open Areas, Dry Washes, or Riverbeds 4/23/1982 47 FR 17485 R9-3-405 Roadways and Streets 4/23/1982 47 FR 17485 R9-3-406 Material Handling 4/23/1982 47 FR 17485 R9-3-407 Storage Piles 4/23/1982 47 FR 17485 R9-3-410 Evaluation of Non-point Source Emissions 4/23/1982 47 FR 17485

R9-3-502 Standards of Performance for Unclassified Sources 10/19/1984 49 FR 41026 R9-3-522 Standards of Performance for Existing Gravel and Stone Crushing Operations 9/28/1982 47 FR 42572

R18-2-702 32 General Provisions 8/24/2004 69 FR 51952

### 38 5.1.2 RACM Analysis for the Nogales NA Area

The emissions inventory in ADEQ’s 1993 Noga les NA SIP identified emissions from unpaved roads as the greatest source of PM 10 emissions gene rated in the Nogales NA. 33 ADEQ accordingly consulted EPA guidance (57 FR 13540; April 16, 1992) to identify control measures for inclusion in the 1993 Nogales Nonattainment Area (N A) SIP. This subsection exam ines the selection process, implementation, current status and applicability of co ntrol measures required in ADEQ’s 1993 SIP for the Nogales NA.

Because no new significant source categories we re identified in the 2008 emissions inventory, ADEQ determined that the control measures from th e 1993 Nogales NA SIP are still appropriate controls for the area. The following sections discuss why th e RACM/RACT were initially selected and provides an explanation of their implementation status. The control measures selected in the 1993 Nogales NA SIP continue to be required in this SIP revision. Some of the 1993 control measures are not submitted for incorporation within the SIP and SIP credit because they are not enforceable by the State or have not been submitted to the Arizona SIP; those meas ures are clearly labeled as such.

5.2 Control Measures Adopted into the SIP and Implemented by ADEQ

The control measures implemented by ADEQ include the following:

1. Require RACT for stack and fugitive PM 10 from permitted stationary sources; 2. Require RACT for haul roads and staging areas;
3. Require dust control measures for material storage piles; 4. Limit Use of Recreation Vehicles on Open Land.

Most of these control measures are listed in Table 5-1 and are discussed further below.

5.2.1 Require RACT for Stack and Fugitive PM 10 from Permitted Stationary Sources/ Require RACT for Haul Roads and Staging Areas

In the 1993 Nogales NA SIP, ADEQ committed to implement the RACM/RACT for stack and fugitive emissions from permitted stationary sources, haul roads and staging areas, and material storage piles. The sources permitted by ADEQ shown in Ta ble 5.2 were in operation during 2008. With the exception of the UNS Electric facility, which operat es under a Title V permit, the sources below operate under one of ADEQ’s general permits that require RA CM/RACT appropriate for the source. In addition, R18-2-702, effective February 3, 2004 (69 FR 5159 2; August 28, 2004) establishes a 20 percent opacity standard for point sources in all moderate PM 10 nonattainment and maintenance areas, including the Nogales NA, and qualifies as RACM. EPA states, "Where the sources affected by a particular measure

33 See Table 3.1 on page 27 of the 1993 NA SIP. “Final State Implementation Plan for the Nogales PM 10 Nonattainment Area.” ADEQ. Submitted to EPA June 14, 1993. <http: //www.azdeq.gov/environ/air/ plan/download/nogpm10sip_061993.pdf >

### 39 contribute only negligibly to ambient concentrati ons that exceed the NAAQS, EPA's policy is that it
would be unreasonable and therefore would not constitute RACM to require controls on the source." 34 Emissions from permitted sources meet these crite ria and, therefore, do not require RACM.

Table 5.2

PM 10 Generating Point Sources Operating in the Nogales NA in 2008 Company Name Place Description PM 10 TPY Type

County Health Department Boilers and Generators 0.019 Stationary

AT&T Generator 0.002 Stationary
Steris Inc. Medical Device Sterilization N/A 35 Stationary
UNS Electric Inc. Utilities – Natural Gas 0.610 Stationary
Wash and Clean World Dry Cleaners 0.011 Stationary
CEMEX Construction Materials South Concrete Batch Plant 1.662 Portable

Total 2.3 tpy

Source: ADEQ.

5.2.2 Require Dust Control Measures for Material Storage Piles

AAC R9-3-407, approved into the Arizona SIP by EPA April 23, 1982 (47 FR 17485), prescribes the following requirements for storage piles:

A. No person shall cause, suffer, allow, or permit organic or inorganic dust producing material to be stacked, piled, or otherwise stored without taking reasona ble precautions such as chemical stabilization, wetting, or covering to prevent excessive amounts of par ticulate matter from becoming airborne.

B. Stacking and reclaiming machinery utilized at st orage piles shall be operated at all times with a minimum fall of material and in such manner, or with the use of spray bars and wetting agents, as to prevent excessive amounts of particulate matter from becoming airborne.

ADEQ officials are authorized to issue citations for violating the law.

5.2.3 Limit Use of Recreation Vehicles on Open Land

The City of Nogales is well-developed and city officials confirm there are no open public areas where off-highway vehicles (OHVs) can be used within its borders. The prohibition on OHV use is enforced by local law enfo rcement agencies. Portions of the N ogales NA with open areas are subject to

34 EPA. PM 10 Moderate Area SIP Guidance: Final St aff Work Product. April 2, 1991. <http://gate1.baaqmd.gov/pdf/1321_PM10_Moderate_Are a_SIP_Guidance_Final_Staff_Work_Product_1991.pdf >

35 Exact emissions for Steris Inc are not available as their emissions are below reporting requirements. If a source emits below one ton per year of any single pollutant or below two and one-half tons of combined pollutants, the source is not required to report their emissions to ADEQ.

### 40 Arizona Administrative Code (AAC) R9-3-404 - Open Areas, Dry Washes, or Riverbeds, approved into the Arizona SIP on October 19, 1984 (49 FR 41026), which establishes that “ No person shall operate a motor vehicle for recreational purposes in a dry wash, riverbed or open area in such a way as to cause or
contribute to visible dust emissions which then cross property lines into a residential, recreational, institutional, educational, retail sales, hotel or bus iness premises. For purposes of this subsection "motor vehicles" shall include, but not be limited to tr ucks, cars, cycles, bikes, buggies and 3-wheelers. Any person who violates the provisions of this subsecti on shall be subject to prosecution under A.R.S. § 49-
463.” 36 Enforcement of the law is provided by Arizona De partment of Public Safety officers, sheriffs, police, and State and federal land ma nagers. Violations of the law may lead to penalties reaching $500.00.

5.3. Status of 1993 Nogales NA SIP Control Measures Implemented by the City of Nogales and/or Santa Cruz County Meeting RACM

This section provides a status report on the control measures included in the 1993 Nogales NA SIP implemented by the City of Nogales and Santa Cruz County. These measures are included in this SIP revision and continue to be enforceable and implemented.

5.3.1 Pave or Chemically Stabilize Unpaved Roads; Pave, Vegetate or Chemically Stabilize Access Points Where Unpaved Traffic Surfaces Adjoin Paved Roads

All public roads in the City of Nogales have been paved and accepted into the City’s Street Maintenance Program; therefore, there are no unpaved/ paved road access points between adjoining public
roads. 37 Santa Cruz County officials confirm the portions of Rio Rico within the nonattainment area boundaries include approximately 200 miles of paved/ double chip-sealed roads, with approximately 40 miles of unpaved roads at present. 38 Because the map provided by the County does not differentiate between paved and unpaved roads, ADEQ created its own map of unpaved roads in the Nogales NA; the map is included in Appendix E.3. ADEQ's estimate fo r double chip-sealed roads in the Rio Rico portions of the nonattainment area is 134.4 miles; th e estimate for unpaved roads is 53.5 miles.

Between 1992 and 2008, 17.5 combined miles of roadway were paved or double chip-sealed in the Rio Rico and Nogales portions of the Nogales NA. In Appendix E, the State presents two methods of calculating emission reductions for these chip seal ed roadways. Method One assumes double chip-sealing provides 90 percent control efficiency of emissi ons; Method Two assumes double chip-sealing provides emissions rates equivalent to paving the roadways.

36 Arizona Administrative Code. R18-2-604, formerly R9-3-404, approved by EPA in 1984 (49 FR 17485). <http://www.azsos.gov/public_s ervices/Title_18/18-02.htm >

37 Correspondence. Juan Guerra, Nogales City Engineer. See Appendix F.3.

38 Correspondence. Jesus Valdez, P.E. Interi m Public Works Director County Engineer , Santa Cruz County. See Appendix F.2.

### 41 Within the 1993 Nogales NA SIP, the City of Nogales committed to pave several roadways within the city limits by 1998. 39 In an implementation review using aerial photography, ADEQ identified eleven unpaved roads that were paved between 1992 and 1996 totaling 8. 4 miles. Because traffic data could not be located for two of the eleven roadways (Hohokam and La Quinta Roads) emission reductions were not calculated for them. For the remaining 9 unpaved roads totaling 7.7 m iles, the annual emission reduction associated with their paving is estimated to be 78.45 tons per year, as shown in Table 5.3. 40 See Appendix E for calculations.

In a similar implementation review using aerial photography 41 and data provided by Santa Cruz County, 42 ADEQ also reviewed 39.8 miles of road paving/double chip-sealing completed by the County in the Rio Rico community in and around the Nogales NA between 2002-2008. Of those, ADEQ identified four unpaved roads within the Nogales NA tota ling 9.75 miles, as shown in Table 5.4. 43 The annual emission reductions associated with the paving of these four unpaved roads is estimated to be 107.4 tons per year. See Appendix E for calculations. While th ere was an additional est imated 40 miles of pa ving/double chip-sealing projects on unpaved roads in the Rio Rico community between 1994-2001, Santa Cruz County could not locate records detailed enough to allow ADEQ to calculate emission reductions for the subset of these projects
located in the nonattainment area. 44 As a result, ADEQ did not claim emissions reductions for these projects.

As shown in Tables 5.3 and 5.4, within the Nogales NA, the City of Nogales and Santa Cruz County have paved 17.45 miles of unpaved roads resulting in 185.5 tpy of emissions reductions based on Method 2.

Table 5.3
Calculated PM 10 Emissions for Roads in the City of Nogales, Arizona 1993-1996

Roadway Miles
Paved VMT Unpaved
Emissions

(tons) Paved
Emissions

(tons) Royal Rd 0.9 16178 4.55 0.0086
Vista del Cielo 2.2 160072 45.06 0.0848
Yucca Drive S. 2.0 13696 3.86 0.0073
Bristol Dr 0.4 7875 2.22 0.0042
Frank Reed Rd 0.95 62616 17.63 0.0332
Kino Rd 0.28 3835 1.08 0.0020 Kelsey Rd 0.27 6240 1.76 0.0033

West 1st St 0.4 6848 1.93 0.0036 Target Range Rd 0.2 1294 0.36 0.0007

Total 7.7 278655 78.45 0.148

39 Pages 31-32 of “Final State Implementation Plan for the Nogales PM 10 Nonattainment Area.” ADEQ. Submitted to EPA June 14, 1993. <http://www.azdeq.gov/environ/ air/plan/download/nogpm10sip_061993.pdf >

40 See Appendix E, Table E.5.

41 Correspondence. Letter from EPA to ADEQ dated November 30, 1993. See Appendix E.4.

42 Correspondence. Jesus Valdez, Interim Public Works Dir ector, Santa Cruz County Engineer. See Appendix F.2.

43 See Appendix E, Table E.1.

44 Correspondence. Jesus Valdez, In terim Public Works Director, Santa Cruz County Engineer . See Appendix F.5.

### 42 Table 5.4
Calculated PM 10 Emissions for Roads in Rio Rico within the Nogales NA, 2002-2008

Roadway Miles
Paved VMT Unpaved
Emissions (tons) Paved
Emissions (tons)
Calle Arikara 1.09 22694 5.9 0.011
Paseo Mexico 4.03 195774 35.5 0.067Calle CoyoteAnnette Ct 1.92 65679 18.5 0.035

Paseo Guebabi 2.70 168746 47.5 0.089

Total 9.75 452893 107.4 0.202

ADEQ used the latest satellite images available to assess paved and unpaved road intersections in Rio Rico in 2011 and found that, typically, intersecti ons provided adequate stabilization of unpaved roads to mitigate trackout. As shown in Figure 5.1, soil trackout from the typical unpaved road in Rio Rico visibly trails off as vehicles approach the main pa ved road due to the paved apron transition area, decreasing trackout and reentrained emissions. Figure 5. 1 is only provided as a demonstration of a typical apron in Rio Rico located with Google Maps; the inte rsection of Calle Remedios and Calle Carmelita is an example of the County's efforts to mitigate trackout onto paved roads.

Figure 5.1 Typical Intersection of Paved and Unpaved Road in Rio Rico

Source: Google Maps.

### 43 As part of preventing track out on to paved roads, Section 8-8-2, Streets, of the City of Nogales Code requires curbing of paved ro ads and Section 8-9-5, General Parking Lot Design Requirements, requires paving of commercial parking lots; these meas ures are included as supplementary information in Appendix G and are not included for submittal with this SIP or for consideration as RACM.

5.4 Control Measure Implemented by Agenci es but not included in the SIP for Credit

The control measures in this section provide a dditional emissions reductions in the Nogales NA
but are not claimed for credit.

5.4.1 General Services Administration (GSA) Reduce Idling Time of Diesel-Powered
Vehicular Traffic at Border Entrances

As reported by ADEQ in its 1996 Reasonable Further Progress report, 45 by 1994 the GSA expanded the number of northbound vehicle lanes at th e DeConcini Port of Entry (POE) from four to eight, and added three northbound lanes at the Mari posa POE. These actions provided supplemental
reductions in exhaust and brake wear emissions , vehicle stops and starts, and idling time.

5.4.2 Provide for Storm Water Drainage to Prevent Soil Erosion onto Paved Roads/ Provide for Traffic Rerouting or Rapid Clean Up of Temporary Sources of Dust on
Paved Roads

Two problem storm drainage areas in the City of Nogales identified in the 1993 Nogales NA SIP (Meadow Hills, Yucca Drive) were repaired with box culverts and pa ved with concrete. The City owns two standard street sweepers; ma intenance is performed on a 5-day, 40-hour weekly basis. 46 Santa Cruz County implemented an on-call program for Public Works De partment employees to be on standby after normal working hours to respond to road emergencies and/or ro ad blockage following a storm. Public Works crews immediately perform clean up after every storm ev ent by removing debris and sweeping the road. 47 The County currently has two standa rd street sweepers. The C ounty cleans roads on a routine, 5-day, 40-hour workweek basis. Section 8-6-6 of the City of Noga les Code, Surface Drainage and Storm Sewer System, and 8-16-23, Design Standards for On-site Retention of Storm Water, provide measures to prevent storm water and soil from flooding city streets. The County and City have local laws to prevent water erosion onto paved roads; these measures are included as suppleme ntary information in Appendix G and are not included
for submittal with this SIP.

45 ADEQ. Nogales PM 10 Nonattainment Area Quantitative Mi lestone/Reasonable Further Progress Re port. June 12, 1996. See Appendix I.

46 Correspondence. Juan Guerra, Nogales City Engineer. See Appendix F.3.

47 Correspondence. Jesus Valdez, P.E. Inte rim Public Works Director, Santa Cruz County Engineer. See Appendix F.2.

### 44 5.4.3 Prohibit Permanent Unpaved Haul Roads, and Parking or Staging Areas at Commercial, Municipal, or Industrial Facilities

Section 8-9-5 of the Nogales City Building Code , General Parking Lot Design Requirements, and Article 11 of the Santa Cruz County Zoning Code provi de regulations for this category and are included as supplementary information in Appendix G. RACM for haul roads required by the operating permits issued by ADEQ for sources in the Nogales NA is discussed in subsection 5.2.1.

5.4.4 Require Haul Trucks to be Covered

Arizona Revised Statute 28-1098, effective September 19, 2007, requires that “For the purpose of highway safety or air pollution prevention, a p erson shall not drive or move a vehicle on a highway
unless the vehicle is constructed or loaded in a manner to prevent any of its load from dropping, sifting, leaking or otherwise esc aping from the vehicle...A person shall not operate a vehicle on a highway with a load unless the load and any covering on the load are s ecurely fastened in a manner to prevent the covering or load from becoming loose, detached or in any manner a hazard to other users of the highway.” Department of Public Safety deputies and local law enforcement officials are authorized to issue citations for violating the law. [Emission reductions resulting from enforcement of ARS 28-1098 are supplemental for this plan.]

5.5 Nogales NA RACM/RACT Conclusion

The implementation of these measures ensured the Nogales NA attained the PM 10 standard by the December 31, 1994 deadline established by the 1990 amendments of the CAA (76 FR 1532; January 11, 2011). Monitoring data following the implementati on of these measures demonstrates emissions
reductions were sufficient to attain the NAAQS through 1998. As discussed in Section 4.0, subsequent
violations of the PM 10 NAAQS can be attributed to emissions originating in Mexico. The RACM identified by ADEQ’s 1993 Nogales NA PM 10 SIP are still appropriate controls based on the 2008 base year emissions inventory included in Section 3.0.

The greatest emissions sources, fugitive emissions from unpaved roads, have been effectively controlled in the Nogales NA as discussed earlier in th is chapter. All public roads within the City of Nogales have been paved. Approximately 80 miles of roads in Rio Rico have been double chip-sealed, although emission reduction credit is taken for only 9. 75 miles within the Nogales NA that could be verified with documentation. Implementation analys is of road paving projects completed within the Nogales NA by the City of Nogales and Santa Cr uz County over the period 1992-2008 show that a combined total of 17.45 miles of unpaved roads ha ve been paved/double chip-sealed, resulting in a reduction of 185.5 tons per year in PM 10 emissions.

To control fugitive emissions from paved roads, both the City of Nogales and Santa Cruz County own two standard street sweepers. The City and Co unty clean roads on a routine, 5-day, 40-hour work

### 45 week basis. Appendix G includes supplementary info rmation on local ordinances and codes that help control emissions from this category.

In conclusion, paving project RACM/RACT im plemented in the Nogales NA by the City of Nogales and Santa Cruz County are permanent and c ontinue to produce emission reductions. State control measures supporting the plan have been incorporated within the SIP (see Table 5.1). Control measures implemented by the GSA, by Santa Cruz County, and by the City of Nogales provide additional
emissions reductions toward attainment but are not credited in this plan.

### 46 6.0 REASONABLE FURTHER PROGRESS AND CONTINGENCY MEASURES

The federal Clean Air Act (CAA), Section 189(c), requires PM 10 nonattainment areas to include reasonable further progress (RFP) milestones, which are to be achieved every three years until the area is redesignated attainment or meets the NAAQS.

On January 11, 2011, EPA promulgated a determination of attainment as of the applicable attainment date for the Nogales NA based on ambient air quality mo nitoring data from 1992-199 4, retroactively affirming
that the area had met the PM 10 NAAQS by the December 31, 1994 deadline established by the 1990 amendments of the CAA (76 FR 1532; January 11, 2011) based on emissions reductions from control measures included in the 1993 Nogales NA SIP. EPA’s retroactive acknowledgment that the Nogales NA had met the NAAQS by the 1994 deadline affirms RFP milestones were met.

In 59 FR 41998 (August 16, 1994) EPA stated that if such a border area failed to achieve RFP
milestones reductions in PM 10 emissions from sources within the U.S ., then contingency measures would be required. 48 Because RFP milestones were me t in the Nogales NA, contingenc y measures are not required.

In the same Federal Register notice, EPA also stat ed that if the area fails to obtain the emission reductions necessary to demonstrate attainment of the NAAQS "but for" emissions emanating from outside the U.S., contingency measures would not be required.

As demonstrated by Chapter 4 and the supporting analyses almost all of the observed exceedances
of the PM 10 standard are due to emissions from Mexico. Pa ving projects completed in the Nogales NA by the City of Nogales and Santa Cr uz County have gone beyond what R FP milestones would have been required if the area had not met the NAAQS by the 19 94 attainment date. Consistent with the EPA guidance cited above, the State is not including contingenc y measures or RFP milestones in this plan.

48 59 FR 41998 (August 16, 1994). "State Implem entation Plans for Serious PM 10 Nonattainment Areas, and Attainment Date Waivers for

PM 10 Nonattainment Areas Generally; Addendum to the General Preamble for the Implemen tation of Title I of the Clean Air Act
Amendments of 1990."

### 47 7.0 TRANSPORTATION CONFORMITY PROCEDURES AND MOTOR VEHICLE
EMISSIONS BUDGET

Transportation conformity is a federal re gulatory process that ensures coordination and consistency between transportation and air quality pl anning. The Clean Air Act (CAA) prohibits federal agencies from approving or funding transportation projects if they are not consistent with State air quality plans. Conforming to a SIP ensures that transportation projects are consistent with a SIP and do not delay
attainment or cause violations of the PM 10 standards in the nonattainment area. The Transportation Conformity Rule (40 CFR Part 93) also requires Stat es to develop a limit or “budget” for on-road mobile
source emissions in the nonattainment area. The mo tor vehicle emissions budget (MVEB) ensures that emissions associated with transportation project s will not result in an exceedance of the NAAQS. Transportation plans and programs produced by the tr ansportation planning process are required to result in on-road emissions that are within the budget.

Normally, States are required to consult with local metropolitan planning organizations (MPOs) when developing a MVEB. The Nogales NA does not have an MPO. To develop the MVEB, ADEQ consulted with EPA and the Arizona Department of Transportation (ADOT). The State chose 2011 as the year for the MVEB.

EPA’s new MOVES2010 (MOVES) emissions mode l for onroad mobile sources was used to estimate the on-road motor vehicle portion of th e 2011 MVEB. MOVES is used to estimate tailpipe emissions from cars, trucks, motorcycles, buses, as well as brake and tire wear. EPA based MOVES on analyses of millions of emission test results, cons iderable advances in EPA’s understanding of vehicle emissions, emissions reductions associated with ne w fleets of cleaner vehicles, and cleaner fuel specifications.

EPA ran the MOVES model for 2011 to prod uce countywide estimates for onroad mobile sources. The estimates were then scaled to the Noga les NA based on Census Bureau population data. To
be conservative and to reflect the most current population data, a 0.569 ratio was used to allocate countywide emissions to the Nogales NA instead of the 0.551 ratio used for 2008 population-based
allocations. Vehicular emissions cal culated using MOVES account for just 1.4 percent of the Nogales NA 2011 projected year inventory and 1.7 percent of the MVEB.

The Federal Highway Administration's Highway Statistics statewide series data on Arizona
shows a decline in Vehicle Mil es Traveled (VMT) between 2007 and 2008, and no change in VMT
between 2008 and 2009. This trend is consistent with economic conditi ons. Emission inventory estimates for 2011 show a slight decrease in VMT. While emissions from vehicles are insignificant in terms of the annual inventory, ADEQ is nevertheless including these categories in the MVEB for the Nogales NA.

Fugitive emissions from paved and unpaved roads are affected by the number of vehicle miles traveled (VMT), silt volume on paved roads, and ot her local factors. Emissions estimates for these categories were based on data obtained from State a nd federal agencies for the 2008 NEI. Estimates for Santa Cruz County were then apportioned to the Nogales NA based on population. The 2011 PM 10 motor

### 48 vehicle emissions budget for the Nogales NA was calcula ted to be 1,274.3 tons per year (tpy). Once EPA finds this budget adequate and/ or approves the budget, ADOT and FHWA must use these budgets in transportation conformity determinations after the eff ective date of the approval or adequacy finding,
whichever is earlier.

As established by the technical demonstrations in Chapter Four, emissions from Mexico are responsible for PM 10 exceedances recorded in the Nogales NA. The emissions inventories in Chapter Three, based on estimates from EPA's 2008 National Emi ssions Inventory (NEI), cite road construction dust as the second-highest emissions source. The 2008 NEI estimates for road construction in the Nogales NA were based on statewide housing starts in a 2006 FHWA report when the housing market was robust, not actual conditions in the Nogales NA in 2008. A statewide estimate w as then allocated to the county level based on population. As discussed in Chapter One, population growth in the Nogales NA has been low in recent years, much lower than other areas in the State where housing starts were thriving.

In addition, there have been no substantial road construction projects in the Nogales NA in the last five years and no projects are planned for the next five years; therefore, estimates for this category present a conservative worst-case scenario, not actual emissions. 49

Table 7.1 2011 Nogales NA Motor Vehicle Emissions Budget
Sector PM 10 tpy Dust – Unpaved Road Dust 864.9
Dust – Paved Road Dust 121.4
Dust – Road Construction 267.0

Mobile – Gasoline and Diesel (including Exhaust, Brake and Tire Wear) 21.0

2011 MVEB 1274.3

Source: 2011 PM 10 Emissions Inventories for the Nogales NA, Santa Cruz County, Arizona (see Appendix B).

49 Email, Beverly Chenausky, Arizona Department of Transportation. June 25, 2012.

### 49 8.0 SUMMARY & CONCLUSIONS

The Nogales NA was designated as nonattainm ent following the 1990 amendments to the CAA,
when all areas where violations of the PM 10 NAAQS had been recorded were designated nonattainment for

PM 10 by operation of law and classifi ed “moderate” upon enactment of the Amendments. The October 1987

PM 10 emissions inventory for the Nogales NA estimated PM 10 emissions on both sides of the U.S.-Mexico
border. The 1987 emissions inventor y estimated that 94 percent of PM 10 emissions in Ambos Nogales are from Mexico, primarily from unpaved roads. 50

ADEQ followed EPA guidance to select RACM/RACT for inclusion in 1993 Nogales NA SIP.
These measures resulted in emissions reductions sufficient to meet the PM 10 NAAQS by the December 31, 1994 deadline established by the 1990 amendments to the CAA, (See 76 FR 1532, January 11, 2011). A period of attainment followed through 1998, but th e Nogales NA soon relapsed back into a pattern of
intermittent exceedances of the NAAQS that has endured.

An analysis of the monitoring data from 1985-2010 de monstrates ambient con centrations fluctuate, based on activity in Nogales, Sonora, Mexico. The Nogales NA did not meet the NAAQS based on monitoring data from 2008-2010; pr eliminary data indicate exceed ances of the NAAQS in 2011 were recorded in the Nogales NA. The popul ation of the Nogales Municipality, Sonora, is approximately 10 times the population of Nogales, Arizona, as shown in Figure 8.1, and rapid growth is projected to continue.

Figure 8.1 Comparison of Ambos Nogales Population Growth 1995-2010

0 50 100 150 200 250Thousands

Nogales Municipality, Sonora 133,491 159,878 193,517 220,292
Nogales, Arizona 20,184 20,878 20,421 20,837 1995 2000 2005 2010

Source: U.S. Census Bureau and INEGI

.

50 Engineering Science. "PM 10 Emissions Inventory Data for the N ogales Planning Area. " October, 1987. See Appendix C of ADEQ's 1993 Nogales NA PM 10 SIP: <http://www.azdeq.gov/environ/ai r/plan/download/nogpm10sip_061993.pdf >

### 50 A nonattainment area meets the national ambient air quality standard for PM 10 when the expected number of days per calendar year with a tw enty-four hour average concentration above 150 μg/m 3 are less than or equal to one. To determine that the Nogales NA has met the PM 10 standard “but for” emissions from Mexico, the State’s Section 179B analys is must show that no more than th ree exceedances of the standard in a recent consecutive three-year period were due to s ources within the Nogales NA and all other exceedances were caused by sources originating from across the in ternational border. This analysis found that 27 of 29 exceedance days were due to transport of PM 10 emissions from sources on the Nogales, Sonora side of the international border. Consequently, when considering the remaining two exceedances, the expected annual exceedance rate for 2007-2009 is 0.7 exceedances per year . Since the annual expected exceedance rate is less than one, the State has demonstrated that the Nogales NA would attain the PM 10 NAAQS “but for”

PM 10 emissions originating in Mexico.

The 2008 base year emissions inventory showed em issions from unpaved roads are still the largest emission source in the Nogales NA. Because the significant sources have not changed since the implementation of RACM/RACT require d by the 1993 Nogales NA SIP, AD EQ determined those measures are still appropriate for th e Nogales NA. Local paving/double-chip se aling projects implem ented in the City of Nogales and the Rio Rico area within the Nogales NA have resulted in an estimated 185.5 tons of PM 10 reduced, annually (see Appendix E.)

8.1 Commitments

Section 110(a)(2)(A) of the CAA requires that St ates provide for enforceable emissions limitations and other control measures, means, or techniques, as well as schedules for compliance with the PM 10 NAAQS. ADEQ commits to enforc e the measures in this plan to attain the 24-hour average PM 10 NAAQS for the duration of this plan.

ADEQ commits to continue to operate the monitors in the Nogales NA area according to the references and guidelines referenced be low for the duration of this plan.

 40 CFR Part 50, Appendix J, Re ference Method for the Determin ation of Particulate Matter

as PM 10 in the atmosphere;

 40 CFR Part 50, Appendix K, Interpretation of the National Ambient Air Quality Standards for particulate matter; and

 40 CFR Part 58, Appendix A, Quality Assurance Requirements for SLAMS

 Section 2, Quality System Requirements

 Section 3.3 and 3.4.1, Data Quality Assessment Requirements

 Section 4.2, Annual Reports

 Appendix D, Section 2.8, Particulat e Matter Design Criteria for SLAMS

 Appendix E, Probe and Monitoring Path Siting Criteria for Ambient Air Quality Monitoring, Section 8, Particulate Matter.

### 51 8.2 Conformity Commitments

ADEQ commits to work with ADOT and federal agenci es, federal grant recipients, and federal licensees and permittees in the Nogales NA to en sure that requirements in CAA Secti ons 118 and 176 a nd Title 40 C.F.R. § 93 Subparts A and B will be met for applicable pr ojects requiring federal funding and/or approval.

8.3 CAA Section 189 Continuing Commitments

ADEQ commits to continue to fulfill the perm itting requirements of th e CAA Section 189. This
commitment will ensure that all new sources and modi fications to existing sources in the Nogales NA are subject to preconstruction review a nd permitting. All new major sources and major modifications to existing major sources in the Nogales NA are subject to th e New Source Review provisions, including New Source
Review.