## Final

2012 State Implementation Plan

Nogales PM 10 

## Nonattainment Area

July 23, 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 that 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 during in July and August, when warm moist air penetrates Arizona
from the Gulf of Mexico. The area receives approxima tely 8.5 inches of precipitation during this time.
The area receives an average of only 0.22 inches of rain 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 2.3 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 RF P 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 by recorded by the filter-based and
continuously operating monitors. Although there were no exceedanc es recorded by the filter-based
monitor in 2009-2010, preliminary data indicate the filter monitor did violate in 2011. The BAM monitor

did record six exceedances in 2010; however, the BAM monitor experienced significant technical
malfunctions during 2010 resulting in four calendar quart ers with incomplete data. Preliminary 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

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

1999 184 184 152 119 83 15.5

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 recording 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 filter-based monitor
and 7.9 for the BAM monitor. Because the 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 State 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, 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
accounts for 90.2 percent of the 2010 population in the Ambos Nogales area. 21 Figure 4.1, below, depicts

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.

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

### 17 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.

### 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 BAM monitor was
examined; data collected by the BAM in 2010 did no t meet CAA completeness criteria, and 2011 data
was not compiled and certified at the time of th is analysis. Over the 2007-2009 timeframe, 29
exceedances of the NAAQS were reco rded by the continuously ope rating Beta Attenuation Monitor
(BAM) at the Nogales, Arizona Post Office. 23 Data recorded by the BAM monitor was selected for the
analysis because the monitor reco rded the greatest number of exceedances at the monitoring 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 0.067

Calle 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., that contingenc y measures would 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 Federal Highway Administration report when the
housing market was robust, not actual conditions in the Nogales NA in 2008. A statewide estimate was
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 analysis must show th at no more than three 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.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 DocumentationThis page is intentionally blank.

# Clean Air Act, Section 179B Attainment Determination

for the Nogales, Arizona PM 10 

# Nonattainment Area

U.S. Environmental Protection Agency

Region 9

Draft Final: July 20, 2012

### 2



## Table of Contents

1.0 Introduction

1.1 Purpose

1.2 Sources of PM 10 

### 1.3 Geography of the Ambos Nogales Area

2.0 Statutory Requirements, EPA Guidance, and Attainment Standard

2.1 Statutory Requirements

2.2 EPA Guidance 2.3 Guidance for Determining Attainment of the PM 10 

### NAAQS

3.0 Review of Data and Analyses

3.1 Population Estimates

3.2 Emissions Inventories

3.2.1 Nogales, Arizona Emissions Inventory Estimates 3.2.2 Nogales, Sonora Emissions Inventory Estimates 3.2.3 Review and Comparison

3.3 Ambient PM 10 

### Levels, Topography, and Meteorological Data

3.3.1 Analyses of 2007-2009 Exceedance Days 3.3.2 Review of 2010 and 2011 Exceedance Days

4.0 Findings

4.1 A Conceptual Model of 2007-2009 Exceedance Days

4.2 Review of Exceedance Days That Diverge From the Conceptual Model

4.2.1 January 1, 2007 Exceedance Day Review 4.2.2 January 26, 2008 Exceedance Day Review 4.2.3 May 22, 2008 Exceedance Day Review 4.2.4 January 1, 2009 Exceedance Day Review

4.3 Estimate of Expected Exceedance Days “But For” International Transport

4.3.1 Daily Analysis 4.3.2 Hourly Analysis

5.0 Conclusion

### 3

List of Figures

Figure 1: Map of Ambos Nogales Area and Nogales, Arizona PM 10 

### Nonattainment Area Figure 2: Elevated Topographical View of Ambos Nogales Area from Northwest Perspective with Nogales, Sonora Highlighted and International Border in Red Line. Figure 3: Average hourly PM 10 

### concentration, wind speed, and temperature at the Nogales, Arizona Post Office FEM monitor versus time of day for all exceedances,

e xcluding January 1, 2007, May 22, 2008, and January 1, 2009. Figure 4: January 1, 2007 PM 10 

### Concentrations and wind speeds compared to average

PM 10 

### concentrations and windspeeds from Figure 3.

F igure 5: January 26, 2008 PM 10 

### concentrations and wind speeds compared to average

PM 10 

### concentrations and windspeeds from Figure 3. Figure 6: May 22, 2008 PM 10 

### concentrations and wind speeds compared to average PM 10 

### concentrations and windspeeds from Figure 3. Figure 7: January 1, 2009 PM 10 

### concentrations and wind speeds compared to average

PM 10 

### concentrations and windspeeds from Figure 3.

List of Tables

Table 1: 2010 Population: Nogales NAA, Arizona and Nogales Municipality, Mexico Table 2: Nogales, Arizona Exceedances of 24-hour NAAQS From 1995 - 2000 with

1995 a nd 2000 Ambos Nogales Population Data. Table 3: Nogales, Arizona Exceedances of 24-hour NAAQS From 2000 - 2010 with Ambos Nogales 2000, 2005, 2010 Population Data.

Ta ble 4: 2008 Nogales NAA PM 10 

### Emissions Inventor y (tons per year)

Table 5: PM 10 

### Emissions Inventory for Nogales Municipality for 2008 and 2011 (Tons)

Table 6: 2008 PM 10 

### Emission Inventories: Nogales NAA, Arizona and Nogales Municipality, Mexico (low estimate) (tons per year).

Table 7: 2011 PM 10 

### Emission Inventories: Nogales NAA, Arizona and Nogales Municipality, Mexico (low estimate) (tons per year).

Table 8: 2008 PM 10 

### Emission Inventories: Nogales NAA, Arizona and Nogales Municipality, Mexico (high estimate) (tons per year).

Table 9: 2011 PM 10 

### Emission Inventories: Nogales NAA, Arizona and Nogales Municipality, Mexico (high estimate) (tons per year). Table 10: Percentage of observed PM 10 

### concentrations attributable to wind direction; January 1, 2007, May 22, 2008, and January 1, 2009 are excluded from the analysis of exceedance days. Table 11: Hourly ambient PM 10 

### concentrations sorted by concentration and wind direction, 2007-2009 exceedance days Table 12: 2007-2009 Exceedance Days Concentration Values Disaggregated by Southerly Wind Quadrant versus All Other Wind Directions ( g/m 3 

### ). Table 13: January 1, 2007 PM 10 

### Concentration: 24-hour value and hourly values disaggregated by southerly wind quadrant. Table 14: January 26, 2008 PM 10 

### Concentration: 24-hour value and hourly values disaggregated by southerly wind quadrant.

### 4

Table 15: May 22, 2008 PM 10 

### Concentration: 24-hour value and hourly values disaggregated by southerly wind quadrant. Table 16: January 1, 2009 PM 10 

### Concentration: 24-hour value and hourly values disaggregated by southerly wind quadrant.

Appendices

Appendix A: 2008 and 2011 Emissions Inventories for Nogales NAA Appe ndix B: 2008 and 2011 Emissions Inventories for the Nogales Municipality,

S onora, Mexico Appendix C: Analysis of Ambient PM 1 0 

### Levels, Topography, and Meteorological Data in Nogales, Arizona: 2007 - 2009

### 5



## 1.0 Introduction

1.1 Purpose

This document reviews and integrates several analyses of PM 10 

### pollution in and around Nogales, Arizona to determine if the Nogales nonattainment area would have attained the

Na tional Ambient Air Quality Standard (NAAQS) for PM 10 

### but for sources of PM 10 

### in nearby Nogales, Sonora, Mexico. The Arizona Department of Environmental Quality (ADEQ) requested that EPA provide this analysis to support ADEQ’s work on a PM 10 

### State Implementation Plan (SIP) for the Nogales nonattainment area (NAA), located in

S anta Cruz County, Arizona.

1.2 Sources of PM 10



### PM 10 

### refers to particulate matter of ten microns or less in aerodynamic diameter. Another class of particles, denoted as PM 2.5 

### , also called fine particulate, refers to particles of 2.5 microns or less in aerodynamic diameter. PM 10 

### includes both PM 2.5 

### and the particulates with aerodynamic diameter between 2.5 and 10 microns. Sometimes referred to as PM 2.5-

10 

### , this larger fraction of particles between 2.5 and 10 microns is also called “coarse” particulate. While fine particles originate mostly from combustion sources and secondary

a erosol generation processes, coarse particles usually originate from mechanical activities and fugitive source categories. Typical sources of PM 10 

### include fugitive dust, open burning including wild fires, mineral crushing and grinding operations, agricultural activities such as land tilling, dust suspended from vehicle travel on paved and unpaved

roa ds and, to a lesser extent, fuel combustion sources and mobile source exhaust.

1.3 Geography of the Ambos Nogales Area

The combined communities of Nogales, Arizona and Nogales, Sonora, or Ambos Nogales are located within the Sonoran Desert . This desert covers 120,000 square miles

with a minimum elevation of 2,500 feet and is in the Basin and Range topographic province. This topography is characterized by north-south elongated valleys surrounded

b y mountain ranges. Ambos Nogales is located in such a north-south valley created by

the N ogales Wash running north to the Santa Cruz River.

From south to north, Nogales Municipality is roughly analogous to a United States (U.S.) county and covers a 632.5 square mile area along the U.S./Mexico border. 1 

### The largest urban center in the municipality is the City of Nogales, Sonora. Nogales, Sonora, Mexico lies directly south of Nogales, Arizona across the international border. Collectively referred to as Ambos Nogales, the cities of Nogales, Arizona and Nogales, Sonora, Mexico comprise the largest international border community in Arizona, with a combined population of 232,550 inhabitants in 2010. 2 

### The majority of the population within the Nogales Municipality lives within the city of Nogales, Sonora. The mean elevation

1 Nogales Municipality land area was calculated by EPA using GIS software.

2 Nogales, Arizona had 20,017 inhabitants and Nogales, Sonora, Mexico had 212,533 inhabitants. U.S. Census Bureau 2010 and Instituto Nacional de Estadistica Geografia e Informatica, (INEGI) 2010.

### 6

above sea level in Nogales, Sonora is 4,265 feet. 3 

### At 5,380 feet, the highest elevation area in Nogales, Sonora is in the Cerro de los Nogales (Nogales Hill), west of where the Obregón and Colosio routes meet, near the southern end of the city.

Proceeding northward, the U.S. and Mexico border forms the southern boundary of the Nogales NAA and Santa Cruz County, Arizona. Near the center of the Nogales NAA, the city of Nogales, Arizona is sixty miles south of Tucson, Arizona in the middle and

sout hernmost portion of Santa Cruz County. The city of Nogales, Arizona is the largest

c ity in the 76.1 square mile nonattainment area. 4 

### The mean elevation above sea level in Nogales, Arizona is 3,865 fe et

. Mountain ranges near Nogales include the Patagonia Mountains to the east and the Tumacacori, Atascosa, and Pajarito mountains to the west. Appr oximately 25 miles to the north are the Santa Rita Mountains and Madera Canyon in

the Corona do National Forest where Mount Wrightson rises to an elevation of 9,432 feet.

Nor thwest of Interstate 19 are the Cerro Colorado, Las Guijas, and Sierrita Mountain Ranges.

3 “Statistical Municipal Workbook for Nogales, Sonora”, 2005 edition, INEGI.

4 Nogales NAA land area was calculated by EPA using GIS software.

### 7

Figure 1: Map of Ambos Nogales Area and Nogales, Arizona PM 10 

### Nonattainment Area

### 8



## 2.0 Statutory Requirements, EPA Guidance, and Attainment Standard

Because the Nogales NAA lies along the international border with Mexico, there are specific statutory requirements in the Clean Air Act (CAA) that apply to the Nogales NAA. With a demonstration showing that the Nogales NAA would have attained the

PM 10 

### NAAQS but for international sources of PM 10 

### , EPA may approve an attainment plan provided by the State. Such a “but for” attainment demonstration, however, must be consistent with statutory and regulatory requirements. First, we review the statutory basis for a “but for” attainment demonstration. Secondly, we will review EPA’s published guidance on how such an analysis may be structured. Lastly, we will review the attainment standard applied to PM 10 

### nonattainment areas, as stipulated in federal regulations.

2.1 Statutory Requirements

The Nogales NAA shares its southern border with Mexico. For international border

a reas, the Clean Air Act (CAA) section 179B(a) states that:

“ 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 requirements applicable to it under

the chapter other than a requirement that such plan or revision demonstrate attainment and maintenance of 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, 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 sp ecified 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. ”

As stated above, notwithstanding any other provision of law, should Arizona establish to the satisfaction of the EPA Administrator that the Nogales NAA would have attained the

PM 10 

### NAAQS by the applicable attainment date but for emissions emanating from outside the United States (U.S.), then the Nogales NAA shall not be subject to the provisions of CAA section 189(a)(1)(b), requiring a demonstration of attainment of the

PM 10 

### standard by the applicable attainment date.

Section 179B(d ) g oes on to state that should Arizona provide a demonstration showing that the Nogales NAA would have attained the PM 10 

### NAAQS but for emissions emanating from outside the U.S., then the Nogales NAA shall not be subject to the provisions of CAA section 189(b)(2), as well, and should not be reclassified as a

“ serious” PM 10 

### nonattainment area.

### 9

2.2 EPA Guidance

EPA has issued guidance relating to serious PM 10 

### nonattainment areas (General Preamble); this guidance includes a discussion of the requirements applicable to

international border areas. 5 

### The General Preamble reviews the information and methods that may be used to determine if an international border area qualifies for treatment under CAA section 179B and to demonstrate that the area would attain the relevant NAAQS

but for emissions emanating from outside the U.S.

The General Preamble provide s that “several types o f information may be used to evaluate the impact of emissions emanating from outside the U.S.” The EPA will

c onsider the information “for individual nonattainment areas on a case- by -case basis in determining whether an area may qualify for treatment under section 179B.” The

Ge neral Preamble suggests five methods that may be used to determine the impact of

e missions emanating from outside the U.S. and states that “the State may use one or more

of these types of information or other techniques, depending on their feasibility and applicability, to evaluate the impact of emissions emanating from outside the U.S. on the nonattainment area.” Below, we discuss the five methods and their applicability to the Noga les NAA.

Method 1: Place several ambient PM 10 

### monitors and a meteorological station measuring wind speed and direction in the U.S. nonattainment area near the international border.

Eva luate and quantify any changes in monitored PM 10 

### concentrations with a change in the predominant wind direction.

We reviewed the ambient PM 10 

### data, meteorology, and topography in the Ambos Nogales area. The State of Arizona maintains a monitor in Nogales, Sonora, as well as, three monitors in Nogales, Arizona. The Nogales, Arizona monitors are divided as follows:

two monitor’s measure ambient PM 10 

### levels; and, one monitor measures ambient PM 2.5 

### levels. Arizona also has two reference monitors at increasing distances from the Nogales NAA. Our analysis of the ambient data, meteorology, and topography is provided in Appendix C and is discussed below in Section 3.3.

Method 2: Comprehensively inventory PM 10 

### emissions within the U.S. in the vicinity of the nonattainment area and demonstrate that those sources, after application of reasonably

av a ilable controls, do not cause the NAAQS to be exceeded. This analysis must include background PM 10 

### in the area. Estimates of background PM 10 

### levels could be based on concentrations measured in a similar area not influenced by emissions from outside the

U.S.

This method implies the use of an air quality model to demonstrate that emissions within the U.S. do not create a violation of the NAAQS. Although a comprehensive, area-wide

5 “State Implementation Plans for Serious PM 10 Nonattainment Areas, and Attainment Date Waivers for

PM 10 Nonattainment Areas Generally; Addendum to the General Preamble for the Implementation

of Title I of the Clean Air Act Amendments of 1990, ” 59 FR 41998, August 16, 1994.

### 10

inventory of PM 10 

### emissions is available for Nogales, Arizona, information about the spatial and temporal distribution of those emissions required to support air quality modeling is not readily available and would require significant effort to develop. Furthermore, given the complex topography of the Ambos Nogales area, it would be a challenging and expensive task to develop an adequate demonstration using available modeling tools.

Method 3: Analyze ambient sample filters for specific types of particles emanating from across the border. Although not required, characteristics of emissions from sources may be helpful so as to better demonstrate the causal relationship with and contribution to

exceedances in the U.S. nonattainment area due to domestic and international sources.

This method is unlikely to produce useful information for Nogales because the large proportion of crustal PM sources on either side of the international border would far outweigh any specific stationary or combustion-based PM source contribution that may be discerned by a filter-based analysis. Also, we did not have specific local and international point source emissions information, such as source specific signature emissions compounds, with which to correlate the filter analyses results that Arizona might have provided.

Method 4: Inventory the sources on both sides of the border and compare the magnitude

of PM 10 

### emissions originating within the U.S. to those emanating from outside the U.S.

We produced two emissions inventories: the first inventory describes the PM 10 

### sources in and around Nogales NAA, Arizona; and, the second inventory describes the PM 10 

### sources in and around Nogales, Sonora, Mexico. Our Nogales NAA, PM 10 

### Emissions Inventory is provided in Appendix A and our Nogales Municipality, Sonora, Mexico Emissions Inventory is provided in Appendix B. The results of both inventories are discussed below in Section 3.2. Also, as a basis for these analyses, we reviewed population estimates and will examine relative population differences in Section 3.1.

Method 5: Perform air dispersion and/or receptor modeling to quantify the relative impacts on the nonattainment area of sources located within the U.S. and of foreign

sources of PM 10 

### emissions.

As discussed above, the information necessary to support air dispersion or receptor modeling is not readily available for the Nogales, Arizona area, nor is it available for the Nogales, Mexico area. For example, we did not have available a gridded emissions inventory or a data set from an extensive monitoring array of ambient PM 10 

### values and meteorological data derived from observations on multiple exceedance days.

We considered a backward wind trajectory analysis using the HYSPLIT model, based on

Eta D ata Assimilation System (EDAS) gridded meteorological data, but did not pursue this analysis. 6 

### Previously, we performed such an analysis for the Nogales, Arizona area

6 The HYSPLIT model refers to the “Hybrid Single Particle Lagrangian Integrated Trajectory” model developed and maintained by the National Oceanic and Atmospheric Administration.

### 11

and found the resulting wind trajectories to be inconclusive. The EDAS has a 40-

k ilometer grid resolution; in contrast, the valley containing Nogales is 20 kilometers wide at its widest point. As a result, the EDAS data were not resolved enough to portray the

sout h- to -north valley air drainage flows that are a key feature of local Nogales meteorology; consequently, we rejected further use of HYSPLIT model for purposes of this Section 179B analysis.

To summarize, we analyzed ambient PM 10 

### levels in and around the Nogales NAA, the local meteorology associated with exceedances of the PM 10 

### standard, and sources of

PM 10 

### emissions on either side of the international border. These analyses are consistent with Methods 1 and 4 described by the General Preamble. We examined Method 3, but did not pursue this avenue of investigation because it was unlikely that we would get definitive results given the large crustal source emissions on either side of the

international border.

Initially, we did not pursue Methods 2 and 5 because we did not have the data and the models required for this type of analysis. Instead, we used the information at hand and, consistent with methods 1 and 4, determined if the Nogales NAA would have attained the standard, but for international emissions. Should these less resource intensive methods have proved inconclusive, we would have considered further analyses consistent with

Methods 2 and 5.

As stated in the General Preamble, the EPA will consider the information “for individual

nona ttainment areas on a case- by -case basis in determining whether an area may qualify for treatment under section 179B.” Because the individual circumstances surrounding a nonattainment area may differ widely whether by data, resources, or emissions sources, EPA anticipates that “the State may use one or more of these types of information or other techniques, depending on their feasibility and applicability, to evaluate the impact of emissions emanating from outside the U.S. on the nonattainment area.” The analysis provided below for the Nogales NAA is specific to this nonattainment area only and the timeframe, data, and circumstances therein.

2.3 Guidance for Determining Attainment of the PM 10 

### NAAQS

EPA determines whether an area's air quality is meeting the PM 10 

### NAAQS based upon air quality data gathered at monitoring sites in the nonattainment area. Then, EPA reviews the data to determine the area's air quality status according to 40 CFR part 50, appendix K (the Attainment Guidance). Three consecutive years of clean air quality data (i.e., no more than one expected exceedance per year) is generally needed to show attainment of the twenty-four hour PM 10 

### standard. As defined by 40 CFR part 50, appendix K, a complete year of air quality data is composed of all four calendar quarters

with ea ch quarter containing data from at least 75 percent of the scheduled sampling days.

Under the Attainment Guidance, a nonattainment area meets the twenty-four hour PM 10 

### NA AQS when the expected number of days per calendar year with a twenty-four hour

### 12

average concentration above 150 micrograms per cubic meter (μg/m 3 

### ) is equal to or less than one. In general, the number of expected exceedances at a site which samples every day is determined by recording the number of exceedances in each calendar year and then averaging them over the most recent three calendar years. For sites which do not sample

e very day, EPA requires adjusting the observed exceedances to account for days not sampled. The procedures for making this data adjustment are specified in 40 CFR part 50, appendix K.

For this review of the Nogales NAA and the contribution of international emissions, we are analyzing ambient air quality data from 2007-2009 as representing the most recent and complete three-year data set certified by Arizona. The 2010 data set is incomplete and the 2011 data set has yet to be submitted to EPA and certified as meeting the relevant quality control and quality assurance requirements. The standard we will use to

determine attainment of the PM 10 

### NAAQS, “but for” international emissions, is similar tothe one described above: the expected number of days per calendar year with a twentyfour hour average concentration above 150 μg/m 3 

### must be equal to or less than one. To determine that the Nogales NAA has met the PM 10 

### standard “but for” emissions from Mexico, the analysis must show that no more than three exceedances, based on data completeness and every day sampling, in the 2007-2009 analysis period were caused by

emission sources on the U.S. side of the border.



## 3.0 Review of Data and Analyses

In this section, we review the relevant data and observations taken from the following supporting analyses described in Section 2.2:

2008 and 2011 Emissions Inventories for the Nogales NAA; 2008 and 2011 Emissions Inventories for the Nogales Municipality, Sonora, Mexico; and, Analysis of Ambient PM 1 0 

### Levels, Topography, and Meteorological Data in Nogales, Arizona: 2007 - 2009

.

These analyses are summarized here and provided in their entirety within the appendices

of this document.

3.1 Population Estimates

I n producing emissions inventories, we reviewed recent 2010 population information

from the U.S. Census Bureau and Mexican Census data from the Instituto Nacional de Estadistica Geografia e Informatica (INEGI). While population estimates, by themselves, are not proximal indicators of emissions activity, these estimates provide an indication of relative human activity and resulting PM 10 

### emissions on either side of the international

border.

### 13

Table 1: 2010 Population: Nogales NAA, Arizona and Nogales Municipality, Mexico

Area Population Percent Nogales NAA, Arizona 24,059 9.8% Nogales Municipality, Mexico 220,292 90.2%

Total 244,351 100%



### Although the Nogales Municipality is a larger land area than the Nogales NAA, a large proportion of Municipality’s population is concentrated within the City of Nogales, Sonora and the surrounding area. In sum, 90.2 percent of the 2010 population in the Ambos Nogales area can be attributed to the Mexican side of the international border.

We also examined population change since 1995, when the Nogales NAA had met the

PM 10 

### NAAQS. 7 

### Below, Tables 2 and 3 show population estimates for 1995, 2000, 2005, and 2010 beside the annual number of expected exceedances since 1995.

Table 2: Nogales, Arizona Exceedances of 24-hour NAAQS From 1995 - 2000 with

1995 a nd 2000 Ambos Nogales Population Data. 8

1995 1996 1997 1998 1999 2000
Expected Exceedances:
1 in 6 day monitoring 0.0 0.0 0.0 13.5 15.5 0.0
Continuous monitoring*

--- --- --- --- --- --- Population:
Nogales, Arizona 20,184

--- --- --- --- 20,878
Nogales Municipality 133,491

--- --- --- --- 159,787 *Continuous monitoring started in 2005; see table below. Source for expected exceedance data: Air Quality System Database. Source for 1995 and 2000 population data: INEGI & U.S. Census.



### Table 3: Nogales, Arizona Exceedances of 24-hour NAAQS From 2000 - 2010 with Ambos Nogales 2000, 2005, 2010 Population Data.

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Expected Exceedances:
1 in 6 day monitoring 0.0 6.9 6.1 12.3 0.0 17.9 20.0 6.1 6.6 0.0 0.0
Continuous monitoring

--- --- --- --- --- 29.6 47.9 14.0 13.2 2.0 8.5 *
Population:
Nogales, Arizona 20,878

--- --- --- --- 20,421

--- --- --- --- 20,837
Nogales Municipality 159,787

--- --- --- --- 193,517

--- --- --- --- 220,292 * There were no quarters in 2010 where there was a complete data set per 40 CFR part 50, appendix K; see

Section 3.3.2 for discussion of 2010 data. Source for expected exceedance data: Air Quality System Database. Source for 2000, 2005, and 2010 population data: INEGI & U.S. Census.

7 76 FR 1532, January 11, 2011.

8 The 1995 Nogales, Arizona population estimate was interpolated from 1990 and 2000 U.S. Census figures; 1990 population was 19,489.

### 14

Between 1995 and 2010, Nogales Arizona population has increased slightly, approximately 3 percent, and has fallen since 2000. In contrast, the Nogales Municipality, Sonora population has increased 65 percent in the 1995-2010 timeframe. With exceptions of 2000 and 2004, exceedances of the PM 10 

### standard have been recorded since 1997. The largest number of exceedances, 47.9, was recorded in 2006.

3.2 Emissions Inventories

Starting with information from EPA’s 2008 National Emissions Inventory for Santa Cruz County, Arizona, we estimated 2008 and 2011 emissions inventories for the Nogales

NAA. 9 

### Unfortunately, we did not have a readily available and comparable PM 10 

### emissions data collection system from which to draw from when estimating emissions for the Nogales Municipality, Mexico. Consequently, using the best information publically available at the time of our analysis, we estimated and calculated a source-based

e missions inventory for the Nogales Municipality based primarily on data and methodologies from the 1999 Mexico National Emissions Inventory and a subsequent update providing a 2012 Mexico emissions inventory. 10 

### Because there was a reasonable range of data inputs from which to select in estimating PM 10 

### emissions, particularly for emissions from unpaved and paved roads, we calculated a low and high estimated range

of PM 10 

### emissions for the Nogales Municipality.

3.2.1 Nogales NAA, Arizona Emissions Inventory Estimates

As shown in Table 2 below, in 2008 the majority of PM 10 

### emissions in the Nogales NAA came from fugitive dust from four source categories: unpaved road dust, road construction, commercial/industrial/institutional construction, and paved road dust. Our estimated emissions inventory for 2011 only differed slightly as total emissions decreased from 1,531 tons per year (tpy) in 2008 to 1,528 tpy in 2011, due primarily to new and cleaner engine standards for diesel engines. From 2008 to 2011, the emissions estimated for five of the top six source categories remain unchanged, except for residential wood burning which increases two tons per year. Again, as in 2008, these six source categories account for approximately 95 percent of all PM 10 

### emissions in the Nogales NAA in 2011.

9 See Appendix A: 2008 and 2011 Emissions Inventory for Nogales NAA.

10 These two primary source documents are as follows: “Mexico National Emissions Inventory, 1999: Six Northern States”, Final, April 30, 2004, prepared by Eastern Research Group (ERG), Acosta Y Asociados, and Transengineering, for the Secretariat of the Environment and Natural Resources and the Nationa l Institute of Ecology of Mexico, the United States Environmental Protection Agency, the Western Governors’Association, and the North American Commission for Environmental Cooperation. (1999 Mexico NEI); and

, “Development of Mexico National Emissions Inventory Projections for 2008, 2012, and 2030”, Final, January 9, 2009, prepared by Eastern Research Group, Inc. (ERG) for the Instituto Nacional de Ecologia, Mexico City, Mexico, the National Renewable Energy Laboratory, and the United States Environmental Protection Agency, with assistance from the Western Governors’ Association. (2008- 12 NEI Projections). See Appendix B: 2008 and 2011 Emissions Inventories for the Nogales Municipality, Sonora, Mexico for the complete discussion of the sources and methods use to develop this emissions inventory.

### 15

Table 4: 2008 Nogales NAA PM 10 

### Emissions Inventor y (tons per year) 11

Source Category PM 10 Percent

Dust

- Unpaved Road Dust 86 5 56. 5 %

Dust

- Road Construction 267 17. 4 %

Dust

- Commercial/Industrial/Institutional Construction 14 3 9. 3 %

Dust

- Paved Road Dust 121 7.9 %

Fuel Combustion

- Residential

– Wood 24 1.6%

Dust

- Residential Construction 2 4 1.6%
Waste Disposal

- Residential Garbage Burning 23 1.5%

All other sources 64 4.2 %

Total 1

, 5 31 100% Note: All other sources include emissions from source categories such as all on-road mobile and off-road mobile, all commercial and industrial fuel combustion, agriculture, land clearing and burning activities.



### 3.2.2 Nogales, Sonora, Mexico Emissions Inventory Estimates

While less detailed than the Nogales NAA, Arizona emissions inventory, the Nogales, Sonora emissions inventory shows that the largest contributing sources of PM 10 

### emissions are unpaved and paved road dust followed by residential wood combustion and other area sources. While the high estimate for point sources may be unlikely, we have included it because we did not have readily available source-specific information providing a precise estimate for stationary point sources of PM 10 

### in the Municipality. The methods for calculating these estimates are discussed in Appendix B.

Table 5: PM 10 

### Emissions Inventory for Nogales Municipality for 2008 and 2011 (tons)

Source Category Range 2008 2011

Point Sources Low Estimate 1. 1 1.1
High Estimate 305 3 90

Area Sources Unpaved Road Low Estimate 2

, 14 4 2

, 308
High Estimate 5

, 52 1 5

, 94 4

Paved Road Low Estimate 53 57

High Estimate 646 696
Agricultural Tilling 0. 8 0. 8
Agricultural Burning 1.6 1.6

Residential Wood Combustion 17 6 4 7 Open Burning of Waste 55 5 6

Construction Activities 23 24
Remaining Area Sources 159 1 50

Mobile Sources 80 8 5

Nonroad Sources 20 2 7

Total Low Estimate 2

, 713 2

, 75 7

Total High Estimate 6

, 987 7

, 4 20

Em issions are rounded to the nearest ton/year, or to the nearest tenth of a ton/year for emissions less than 10 tons/year.

11 For all tables and throughout the text, emissions are rounded to the nearest ton/year, or to the nearest tenth of a ton/year for emissions less than 10 tons/year. Due to rounding, totals may not reflect exactly the sum of each category.

### 16

3.2.3 Review and Comparison

Both the Nogales NAA and the Nogales Municipality have similar sources of PM 10 

### , primarily fugitive dust from unpaved and paved roads, as well as combustion sources and construction. A comparison of 2008 and 2011 low emission inventory estimates suggests that there is a 36/64 percent split in total Ambos Nogales emissions between emissions from the Nogales NAA, Arizona and Nogales Municipality, Mexico areas, respectively. To characterize the relative difference by ratio, for every one ton of PM 10 

### emissions produced annually in Nogales NAA there is an estimated 1.8 tons produced in Nogales

Muni cipality.

Table 6: 2008 PM 10 

### Emission Inventories: Nogales NAA, Arizona and Nogales Municipality, Mexico (low estimate) (tons per year)

PM 10 Percent Nogales NAA, Arizona 1

, 5 31 36. 1 % Nogales Municipality, Mexico 2

, 713 6 3

. 9 %

Total 4

, 2 44 100%



### Table 7: 2011 PM 10 

### Emission Inventories: Nogales NAA, Arizona and Nogales Municipality, Mexico (low estimate) (tons per year)

PM 10 Percent

Nogales NAA, Arizona 1

, 52 8 35. 7 %

Nogales Municipality, Mexico 2

, 75 7 64. 3 %

Total 4

, 2 85 100%



### Similarly, a comparison of 2008 and 2011 high emission inventory estimates suggests that there is an 18/82 percent split in total Ambos Nogales emissions between emissions

fr om the Nogales NAA, Arizona and Nogales Municipality, Mexico areas, respectively. Again, to characterize the relative difference by ratio, for every one ton of PM 10 

### emissions produced annually in Nogales NAA there is an estimated 4.6 tons produced in Nogales Municipality.

Table 8: 2008 PM 10 

### Emission Inventories: Nogales NAA, Arizona and Nogales Municipality, Mexico (high estimate) (tons per year)

PM 10 Percent

Nogales NAA, Arizona 1

, 5 31 1 8 %

Nogales Municipality, Mexico 6

, 98 7 82%

Total 8

, 51 8 100%

### 17

Table 9: 2011 PM 10 

### Emission Inventories: Nogales NAA, Arizona and Nogales Municipality, Mexico (high estimate) (tons per year)

PM 10 Percent

Nogales NAA, Arizona 1

, 52 8 17. 1 %

Nogales Municipality, Mexico 7

, 4 20 8 2

. 9 %

Total 8

, 94 8 100%



### To summarize, a comparison of our 2008 and 2011 emissions inventory data suggests that for every one ton of PM 10 

### produced in the Nogales NAA, there were between 1.8 and

4.6 tons of PM 10 

### emissions produced annually in the Nogales Municipality. The emissions sources appear to be similar with the majority of emissions from fugitive dust sources, such as reintrained unpaved and paved road dust.

3. 3 Ambient PM 10 

### Levels, Topography, and Meteorological Data

In our review and analyses, we found that the Ambos Nogales area’s meteorology and topography are likely components of the observed exceedances of PM 10 

### NAAQS and there is a definite south to north directional component to these exceedances; particularly, in reference to the international border between Nogales, Arizona and Nogales, Sonora, Mexico. Over the 2007-2009 timeframe, there were 29 exceedances at the Nogales, Arizona Post Office (Model: Met One BAM 1020) monitor. We are focusing on the data from this particular monitor for the following reasons: it is comparable to the NAAQS; it

ha s recorded all the exceedances; it has recorded hourly ambient values; and, it has a sufficiently complete dataset for comparison to the NAAQS. Arizona has not flagged any of these 2007 through 2009 exceedance days for potential exclusion from air quality planning considerations under EPA’s Exceptional Events Rule.

Our analysis of ambient concentration and meteorological data identified 26 of the 29 exceedances as having nearly identical diurnal patterns; the three exceptions were January 1, 2007, May 22, 2008, and January 1, 2009. 12 

### For each of the 26 days, there is a strong pattern of decreasing PM 10 

### concentrations in the very early morning. The majority of days have a pronounced PM 10 

### increase and drop-off between 6:00 am and 9:00 am, suggesting a reproducible direct PM 10 

### source, noting the times correspond to a morning commute pattern. The PM 10 

### concentrations reach their lowest points between 10:00 am and 4:00 pm, with corresponding increases in ambient temperature and wind speed observed during those times. As temperatures and wind speeds drop in the evening hours, a pronounced spike in PM 10 

### concentration is then observed beginning between 4:00 pm and 6:00 pm, with concentrations remaining high for a couple of hours and gradually dropping off towards midnight. The afternoon spike in PM 10 

### concentrations correlates with a significant drop in temperature and wind speed, and generally a shift to low and variable southerly (from the south) winds.

12 See, in particular, Section 3 of Analysis of Ambient PM 10 Levels, Topography, and Meteorological Data in Nogales, Arizona: 2007 - 2009, in Appendix C.

### 18

Looking at topography from south to north, the highest elevation of a primary roadway transect is at 4,331 feet at the southern edge of Nogales, Sonora, falling to the international border at 3,933 feet, continuing to the northern edge of the Nogales, Arizona

PM 10 

### NAA at 3,425 feet, and elevation continues to fall along the Santa Cruz River watershed to the north to approximately 3100 feet. 13 

### Across this largest 48.5 mile local transect, the elevation falls approximately 1200 feet from south to north.

An examination of a smaller 14.8 mile transect along a similar primary roadway route shows elevation declines on a south to north axis. The Nogales, Sonora sub-transect shows an elevation drop of 201 feet over 4.8 miles to the international border where there is a slight leveling; starting at 4,134 feet at the Nogales, Sonora urban boundary and

dr opping to 3,933 feet at the international border. The Nogales, Arizona sub-transect shows an elevation drop of 508 feet over 10 miles, from the international border to the northern boundary of the Nogales NAA; starting at 3,933 feet and dropping to 3,425

feet. 14 

### In sum, looking at a south to north transect along the Nogales Wash, elevations fall from south to north with the highest elevations in the Nogales, Sonora area. Looking at the general topography of the Ambos Nogales area (from a northwest perspective, see Figure 2), there is a funnel created as the Nogales Wash falls from higher southern elevations to the international border along the route of the Alvaro Obregón Boulevard and into Nogales, Arizona. Small side canyons extend off of the Nogales Wash bottom and into the surrounding hills between the international border and south of the Nogales, Sonora city center, and to a lesser extent into Nogales, Arizona as elevations drop moving

to the north.

13 See Figure 18

, Long Aerial and Elevation Transect of Nogales Arizona and Nogales, Sonora ; Analysis of

Ambient PM 10 Levels, Topography, and Meteorological Data in Nogales, Arizona: 2007 - 2009, in Appendix C.

14 See Figure 19

, Short Aerial and Elevation Transect of Nogales, Arizona and Nogales, Sonora ; Analysis

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

### 19

Figure 2: Elevated Topographical View of Ambos Nogales Area from Northwest Perspective with Nogales, Sonora Highlighted and International Border in Red Line. N

3. 3.1 Analys es of 2007 - 2009 Exceedance Days

In three analyses of ambient PM 10 

### concentrations and wind direction on exceedance days, we found that high PM 10 

### concentrations are associated with wind direction from a southerly quadrant, or southerly air flows more often than what is typically observed on non-exceedance days. Also, we found that the largest number of hourly ambient values

above 150 g/m 3 

### and the highest ambient values, including those markedly above

150 g/m 3 

### , originated from a southerly wind direction quadrant.

In the first analysis, for the 26 exceedance days with nearly identical diurnal patterns, we examined the percent of the total observed 24-hour concentration that is attributable to winds out of specific directional quadrants by performing a weighted analysis of hourly

c oncentrations. The weighted hourly analysis shows that, for non-exceedance days, the

c oncentrations attributable to winds from a southerly wind quadrant are approximately 62

pe rcent of the total observed PM 10



### . When we examine exceedance days, however, concentrations attributable to wind from a southerly wind quadrant increases to 80

pe rcent of the total.

### 20

Table 10: Percentage of observed PM 10 

### concentrations attributable to wind direction. January 1, 2007, May 22, 2008, and January 1, 2009 are excluded from the analysis of exceedance days.

Ambient Data Sample Northerly (315

- 44°) Easterly

(45

- 134°) Southerly

(135

- 224°) Westerly

(225

- 314°)

All Days in 2007

- 2009 11% 1 6 % 63% 10 %

Non

- Exceedance Days 1 2 % 16% 6 2 % 10%

Exceedance Days 7% 10 % 80 % 3%



### In the second analysis, we examined all exceedance days using pollution roses, a method correlating wind direction observations with hourly ambient PM 10 

### concentrations. We found that higher PM 10 

### readings were observed when wind direction was from the southernmost quadrant; see Table 11 below. We found that the largest proportion of hourly values above 150 g/m 3 

### and the highest hourly concentrations were found in the southerly wind direction quadrant. When ambient PM 10 

### values above 150 g/m 3 

### were sorted by 100 g/m 3 

### increments to 550 g/m 3 

### and greater, we found within each

increment above 150 g/m 3 

### that 71 to 92 percent of the ambient PM 10 

### observations were from the southerly wind quadrant. 15



### Table 11: Hourly ambient PM 10 

### concentrations sorted by concentration and wind direction, 2007 - 2009 exceedance days.

Range of Ambient Concentration Values (microgram/m 3 )

Wind

Direction Quadrant < 150 150

- 250 250

- 350 350

- 450 450

- 550 >= 550 Share of All

Wind Direction

Observations Northerly

NW to NNE 2 7 % 6% 3% 3 % 3 % 0% 17%

Easterly

NE to ESE 15% 16% 16% 1 1 % 3 % 8% 14%

Southerly

SE to WSW 4 1 % 71% 72% 8 4 % 9 2 % 92% 5 7 %

Westerly

SW to WNW 1 8 % 6% 8% 3 % 3 % 0% 12%

Total 100% 100% 100% 100% 100% 100% 100%



### Finally, we examined the wind direction and hourly PM 10 

### concentrations on each exceedance day to determine two average ambient values for each exceedance day: one value for the southerly wind quadrant and a second value representing all other wind directions. Table 12 below shows the results. Two exceedance days, January 1, 2007

a nd January 26, 2008, have an average ambient concentration greater than 150 g/m 3 

### for

15 The 80 percent figure in Table 10 represents concentration-weighted hours from the southerly wind quadrant on exceedance days; whereas, the 57 percent figure in Table 11 represents a percentage of hourly observations from the southerly wind quadrant on exceedance days. To explain further, while 57 percent of the winds are from the southerly wind quadrant on exceedance days, there are much higher concentrations coming from those directions.

### 21

the “all other wind direction” quadrants. The ratio of the southerly quadrant concentration to the “all other direction” quadrant concentration ranges from 0.86 to 11, with an average ratio value of 3.83. Only one day, January 1, 2007, has a ratio value less than 1.0; i.e., the “all other direction” quadrants’ share exceeds the southerly quadrant

share.

Table 12: 2007 - 2009 Exceedance Days Concentration Values Disaggregated by

S outherly Wind Quadrant versus All Other Wind Directions ( g/m 3 

### ).

Date 24

- hour

Concentration Southerly Wind Quadrant

Concentration (135 to 224 degrees) All Other Wind

Direction

Concentration (225 to 134 degrees) Concentration Ratio of Southerly Wind Quadrant to Other

Wind Directions

1

- Jan

- 2007 210 199 231 0.86

6

- Feb

- 2007 180 228 100 2.28

6

- Mar

- 2007 157 265 66 4.02

15

- Mar

- 2007 175 360 65 5.54

19

- Oct

- 2007 189 335 43 7.79

27

- Oct

- 2007 210 301 133 2.26

2

- Nov

- 2007 211 278 79 3.52

3

- Nov

- 2007 170 213 128 1.66

4

- Nov

- 2007 170 183 148 1.24

6

- Nov

- 2007 186 209 119 1.76

18

- Nov

- 2007 167 277 38 7.29

19

- Nov

- 2007 177 216 63 3.43

28

- Nov

- 2007 167 278 75 3.71

24

- Dec

- 2007 233 368 45 8.18

26

- Jan

- 2008 204 257 182 1.41

27

- Feb

- 2008 166 251 66 3.80

18

- May

- 2008 169 356 57 6.25

22

- May

- 2008 217 217 No values observed

---
26

- Oct

- 2008 156 219 53 4.13

31

- Oct

- 2008 159 245 74 3.31

1

- Nov

- 2008 234 369 76 4.86

8

- Nov

- 2008 167 197 79 2.49

16

- Nov

- 2008 171 273 69 3.96

17

- Nov

- 2008 206 297 27 11.00

20

- Nov

- 2008 161 225 56 4.02

22

- Nov

- 2008 179 245 102 2.40

31

- Dec

- 2008 155 163 117 1.39

1

- Jan

- 2009 238 323 119 2.71

16

- Jan

- 2009 204 247 119 2.08

### 22

To summarize, we analyzed hourly ambient values on exceedance days in three different ways. We found that high PM 10 

### concentrations are associated with wind direction from a southerly quadrant, or southerly air flows more often than what is typically observed on non-exceedance days. We found that the largest number of hourly ambient values above

150 g/m 3 

### and the highest ambient values, including those markedly above 150 g/m 3



### , originated from a southerly wind direction quadrant. Our third analysis of the hourly ambient data confirms our general findings; however, the January 1, 2007 and January 26, 2008 exceedance days may be exceptions and are discussed in Section 4.2, below.

3.3.2 Review of 2010 and 2011 Exceedance Days

We did not use 2010 and 2011 data for our detailed meteorological analysis and attainment determination for two reasons. First, the 2010 dataset did not meet the completeness criteria specified in 40 CFR part 50, appendix K; no quarter in 2010 had complete data. This was due to a large data gap from March 16 to October 27 resulting from poor quality assurance and control results. Second, the 2011 dataset has yet to be entered completely into the Air Quality System database and certified by Arizona. As stated earlier, a complete year of air quality data, as defined by 40 CFR part 50, appendix K, c omprises al l four

calendar quarters with each quarter containing data from at least 75 percent of the scheduled sampling days. While the 2010 and 2011 ambient data do not

pr ovide the basis for this attainment determination, we examined this data consistent with the analyses presented in this document and found no information to contradict our

conclusions. 16



### While we did not use the data from 2010 and 2011 for our detailed meteorological analyses, we did review this most recent data to see how ambient PM 10 

### levels compare generally to our 2007 - 2009 dataset. In 2010, the Nogales, Arizona Post Office (Model:

Met O ne BAM 1020) monitor recorded six exceedances of the twenty-four hour PM 10 

### NAAQS; these twenty-four hour average ambient values ranged from 159 g /m 3 

### to 191 g/m 3 

### . There was one exceedance of the PM 10 

### standard in 2011. Arizona has not flagged any of these 2010 or 2011 exceedances for potential exclusion from air quality planning considerations under EPA’s Exceptional Events Rule.



## 4.0 Fi ndings

From our three analyses, the Nogales NAA emissions inventory, the Nogales Municipality emissions inventory, and the 2007-2009 Meteorological Analysis, we find:

The majority of exceedances, 79 percent, occur in the October to January timeframe, mostly in November. 17 

### Also, given the high desert environment and

16 See Section 4.5 in Analysis of Ambient PM 10 Levels, Topography, and Meteorological Data in Nogales, Arizona: 2007 - 2009, in Appendix C.

17 See Figure 3, Analysis of Ambient PM 10 Levels, Topography, and Meteorological Data in Nogales, Arizona: 2007 - 2009, in Appendix C.

### 23 winter light regime, temperatures usually drop dramatically, 20 degrees

Fahrenheit over the 3-4 hours after sunset. 18



### From the emission inventories, we estimate that pollution loads may differ by a

ratio of 1.8 - 4.6 to one on a south- to -north basis in relation to the international

border.

The largest sources of PM 10 

### emissions in the Ambos Nogales area are reintrained dust from unpaved and paved roads.

Overall, elevations drop approximately 709 feet across the entire south to north local transect we examined, from the southernmost edge of the Nogales, Sonora urban boundary to the Nogales NAA northern boundary line.

Of the 29 exceedance days in 2007 - 2009, 26 of those days showed a similar

pa ttern of ambient PM 10 

### concentration, wind speeds, wind direction, and temperature variation over a twenty-four hour period; the three exceptions were January 1, 2007, May 22, 2008, and January 1, 2009.

On exceedance days, the largest proportions, 71-92 percent, of hourly values exceeding 150 g/m 3 

### and almost all of the highest observed PM 10 

### concentrations

of observations above 450 g/m 3 

### , 92 percent, are associated with a southerly wind direction quadrant. 19



### The ambient PM 10 

### concentration attributed to the southerly wind quadrant

exceeds 150 g/m 3 

### on all 29 exceedance days. In contrast, two exceedance days from the “all other wind direction” quadrants show a value greater than 150 g/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” quadrants greater than that of the concentration attributed to the southerly wind quadrant: January 1, 2007.

On exceedance days, the average ratio of the southerly wind quadrant share of 24-

hour ambient PM 10 

### values to all other wind quadrants share of ambient values is 3.83 to 1. This ratio is relatively consistent with the estimated pollution loads

ratio of 1.8

- 4.6 to one, from south- to -north across the international border.

18 See Figures 7 and 14, Analysis of Ambient PM 10 Levels, Topography, and Meteorological Data in Nogales, Arizona: 2007 - 2009, in Appendix C.

19 See Table 11 above. For a visual representation of this data, see the pollution roses in Figures 11 and 12, Analysis of Ambient PM 10 Levels, Topography, and Meteorological Data in Nogales, Arizona: 2007 -

2009 , in Appendix C.

### 24

4.1 A Conceptual Model of 2007 - 2009 Exceedance Days

As de scribed above in Section 3.3, 26 of the 29 2007 - 2009 exceedances showed a

sim ilar pattern of ambient PM 10 

### concentration, wind speeds, wind direction, and temperature variation over a twenty-four hour period; the exceptions were January 1, 2007, May 22, 2008, and January 1, 2009. Two of these days, January 1, 2007, and January 1, 2009, with higher early morning PM 10 

### concen trations, only vary slightly from the diurnal profile of PM 10 

### concentrations observed for the other exceedances, but have similar meteorological and concentration patterns throughout the rest of the day. Two of the 29 exceedance days, January 1, 2007, and January 26, 2008, had high average

a mbient concentrations during hours when the wind was out of directions other than the south. Thus, there are twenty-five exceedance days that are equivalent and can be considered here as a group, setting aside the dissimilar exceedance days listed above, January 1, 2007, January 26, 2008, May 22, 2008, and January 1, 2009.

Considering these 25 similar exceedance days, we can postulate how the elements of pollution loads and sources, temperature changes, and wind direction may contribute to producing the majority of observed ambient PM 10 

### values exceeding the NAAQS in Nogales, Arizona. We will review the data concerning January 1, 2007, January 26, 2008, May 22, 2008, and January 1, 2009 in more detail within Section 4.2.

As shown for the average PM 10 

### concentration, wind speed, and temperature profiles in Figure 3, beginning at midnight, there is a strong pattern of decreasing PM 10 

### concentrations from the previous day’s high values into the early morning hours. Then, there is a pronounced PM 10 

### increase and drop-off between 6:00 am and 9:00 am, suggesting a reproducible direct PM 10 

### source, such as reintrained road dust from the morning commute. As morning temperatures rise, so does wind speed as wind direction changes from south to north dispersing the spike in morning PM 10 

### concentrations. The

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 heating portion of a diurnal heating

a nd cooling cycle where heated air flows from lower elevations to the north to the higher

elevations to the south.

As sunset approaches and night falls, the diurnal cooling cycle begins. Ambient temperatures drop and lower elevation air masses no longer rise with convection causing wind speed to drop and wind direction to be variable. As temperatures continue to drop after sunset, wind speeds drop and cold air masses flow down from higher elevations causing wind direction to shift from a variable/northerly direction to a southerly direction. A pronounced spike in PM 10 

### concentration is then observed beginning between 4:00 pm and 6:00 pm; roughly corresponding with the evening commute hours. Concentrations remain high for several hours into the evening and gradually begin to decrease as midnight approaches. The highest concentrations of PM 10 

### occur in these evening hours when reintrained dust from unpaved and paved roads may be captured by cold air flows moving south to north from higher elevations. Also, home heating

### 25

combustion may add a component to the evening PM 10 

### lo ad and be captured in the evening southerly air flows.

Figure 3: Average hourly PM 10 

### concentration, wind speed, and temperature at the Nogales, Arizona Post Office FEM monitor versus time of day for all exceedances, excluding January 1, 2007, May 22, 2008, and January 1, 2009. 20



### This pattern of exceedances is usually 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 systems move through often enough and with enough energy to prevent a stagnant air mass and the diurnal heating and cooling cycle from exerting a strong influence on the local meteorology.

The conceptual model we present is consistent with the study by Arizona State University, “Atmospheric, Hydroclimatic, and Anthropogenic Causes of Fugitive Dust in the Nogales, Arizona-Nogales, Sonora Airshed.” 21 

### In this study – based on a regression analysis of 815 daily PM 10 

### observations at Nogales, Arizona, and 457 daily PM 10

20 The diurnal pattern shown in Figure 3 applies to 25 very similar exceedance days and also includes January 26, 2008. Elements of this discussion, however, may not apply to January 26, 2008 because of the higher observed PM 10 concentrations when winds were from the east southeast. See Section 4.2.3 for a more detailed discussion of the January 26, 2008 exceedance day.

21 Completed in 2002 by A.W. Ellis, the final report is available through The Southwest Center for Environmental Researcy and Policy at http://scerpfiles.org/cont_mgt/doc_files/A- 02 -2.pdf

. 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

0 50 100 150 200 250 300 350 400 450 5000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00Wind Speed(mph)PM10(ug/m3)



### Time (hour)

Concentration

Wind Speed

TemperatureTemperature(Fahrenheit) 80 90

70

60

50

40

30

20

10

### 26

observations at Nogales, Sonora, and other information – the authors conclude that stagnant atmospheric conditions over a large scale (i.e., a stagnant synoptic atmosphere) is the most important factor in predicting high daily PM 10 

### concentrations. 22



### As shown in Table 12 above, for these similar 25 days the ambient concentration attributed to the southerly wind direction quadrant always exceeds the 150 g/m 3 

### level, in most cases markedly. Conversely, the ambient concentration attributed to the all other wind direction quadrants never exceeds the 150 g/m 3 

### level. Across all 25 days, the average of the hourly concentration values for the hours with a southerly wind direction ranges from 163 to 369 g/m 3 

### for each of the days, with an average value across the 25 days of 264 g/m 3 

### . In comparison, the average of the hourly concentration values for all other wind direction quadrants ranges from 38 to 148 g/m 3 

### for each of the days, with an average value across the 25 days of 80 g/m 3



### .

In sum, for 25 of the 29 exceedance days, we have a conceptual model that explains how

exceedances of the PM 10 

### NAAQS occur in Nogales NAA. Moreover, for all of these 25 days, the origin and contribution of PM 10 

### to exceedances of the standard at the Nogales, Arizona Post Office monitor has a very large southerly component. Given the wind direction, the proximity of the monitor to the border, and the comparison of the magnitude of emissions on either side of the border, the majority of the emissions that result in these exceedances most likely originate from the Nogales, Sonora side of the

int ernational border.

4.2 Re view of Exceedance Days That Diverge From the Conceptual Model

The conceptual model of Mexican influence on Nogales NAA PM 10 

### concentrations described above fits the observations on 25 of the 29 exceedance days in 2007-2009. We have identified, however, four specific exceedance days that differ in one or more ways from our conceptual model of PM 10 

### exceedances in the Nogales NAA: January 1, 2007, May 22, 2008, January 26, 2008, and January 1, 2009. We will examine each of these days in further detail to explain the high ambient PM 10 

### values that occurred on those days.

22 With respect to soil moisture, this study noted a weak relationship between hydroclimatological conditions and high PM 10 concentrations, i.e., while the soil is driest during the hot summer months of June through August, high PM 10 concentrations typically occur during late fall through early spring months. In considering soil moisture related predictors of daily PM 10 concentrations, the study did observe that the rate of daily drying is associated with higher observed PM 10 concentrations, and that episodes of high PM 10 were generally marked by more than twice the length of time since the last precipitation event when compared to episodes of low concentration. Despite these associations that soil moisture plays a role in high PM 10 concentrations, the study concluded the following: overall conditions in the Nogales area are conducive to generating PM 10 emissions throughout the year; and, meteorological conditions most strongly distinguish between high and low PM 10 concentrations on a given day.

### 27

4.2.1 January 1, 2007 Exceedance Day Review

Table 13: January 1, 2007 PM 10 

### Concentration: 24-hour value and hourly values disaggregated by southerly wind quadrant.

Figure 4: January 1, 2007 PM 10 

### concentrations and wind speeds compared to average

PM 10 

### concentrations and wind speeds from Figure 3. 23



### As shown in Figure 4, with higher early morning PM 10 

### concentrations contributing more strongly to the high 24-hour average, the PM 10 

### diurnal pattern for January 1, 2007 varies

fr om the average diurnal pattern for the 26 exceedance days. The diurnal pattern after

mid -day looks similar to our conceptual model exceedance day, with an increase in hourly PM 10 

### concentrations at 6:00 pm; however, this increase is less pronounced than our conceptual model exceedance day and the 24-hour exceedance is driven by the high early morning peaks. An examination of the hourly PM 10 

### values shows high PM 10 

### observations, from variable and backing wind directions, and very low wind speeds during the midnight to 8:00 am timeframe.

The average PM 10 

### :PM 2.5 

### ratio of all 2007 - 2009 days with valid samples was 6.24 (standard deviation equals 2.89). The ratio observed on January 1, 2007 is the lowest in

23 As discussed in Section 4.1 and shown in Figure 3, the average PM 10 concentrations and windspeeds depicted in Figures 4, 5, 6, and 7 exclude observations from January 1, 2007, May 22, 2008, and January 1,

2009. 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0

0 100 200 300 400 500 600 700 800 900 100012:00:00...1:00:00 AM2:00:00 AM3:00:00 AM4:00:00 AM5:00:00 AM6:00:00 AM7:00:00 AM8:00:00 AM9:00:00 AM10:00:00...11:00:00...12:00:00...1:00:00 PM2:00:00 PM3:00:00 PM4:00:00 PM5:00:00 PM6:00:00 PM7:00:00 PM8:00:00 PM9:00:00 PM10:00:00...11:00:00...Wind Speed (mph)PM10 Concentration PM10 (ug/m3)

Average PM10

SWS (mph)

Average SWS 24

- hour PM 10 Concentration ( μg/m 3 ) Southerly Wind Quadrant PM 10 C oncentration ( μg/m 3 ) (135 to 224 degrees) All Other Wind Direction PM 10 Concentration ( μg/m 3 ) (225 to 134 degrees)

210 199 (15 of 24 values) 231 (9 of 24 values)

### 28

the 2007 - 2009 sample period (1.49), suggesting that the large early morning ambient

PM 10 

### values were caused by a combustion source such as residential wood burning. 24



### 4.2.2 January 26, 2008 Exceedance Day Review

Table 14: January 26, 2008 PM 10 

### Concentration: 24-hour value and hourly values disaggregated by southerly wind quadrant.

Figure 5: January 26, 2008 PM 10 

### concentrations and wind speed compared average PM 10 

### concentrations and windspeeds from Figure 3.

As shown in Figure 5, the PM 10 

### diurnal pattern for January 26, 2008 is nearly the same as the conceptual model day and the other 25 exceedance days (excluding January 1, 2007, May 22, 2008, and January 1, 2009 from the 29 exceedances), with high evening PM 10 

### concentrations contributing most to the high 24-hour average. The diurnal pattern during

mid -day looks the same as our conceptual model exceedance day, with decreasing hourly

PM 10 

### concentrations from 9:00 am as wind speeds increase. There is a slight morning

PM 10 

### spike beginning at 6:00 am, but that is dispersed by rising low winds, again consistent with our conceptual model day. An examination of the hourly PM 10 

### values shows the highest PM 10 

### observations occurring in the evening (7:00-8:00 pm) from an east southeast direction (ESE); just outside of our defined southerly quadrant of 135-224 degrees. These two hourly values greater than 550 g/m 3 

### are the only two from the ESE direction across all observed values on exceedance days. For further comparison, less

24 For the complete discussion of coarse versus fine particulate matter on all exceedance days, see Section 4.4 and Table 8 of Analysis of Ambient PM 10 Levels, Topography, and Meteorological Data in Nogales,
Arizona: 2007 - 2009, in Appendix C



### . 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0

0 100 200 300 400 500 600 700 800 900 100012:00:00 AM1:00:00 AM2:00:00 AM3:00:00 AM4:00:00 AM5:00:00 AM6:00:00 AM7:00:00 AM8:00:00 AM9:00:00 AM10:00:00 AM11:00:00 AM12:00:00 PM1:00:00 PM2:00:00 PM3:00:00 PM4:00:00 PM5:00:00 PM6:00:00 PM7:00:00 PM8:00:00 PM9:00:00 PM10:00:00 PM11:00:00 PMWind Speed (mph)PM10 Concentration (ug/m3) PM10 (ug/m3)

Average PM10

SWS (mph)

Average SWS 24

- hour Concentration ( μg/m 3 ) Southerly Wind Quadrant

C oncentration ( μg/m 3 ) (135 to 224 degrees) All Other Wind Direction

Concentration ( μg/m 3 ) (225 to 134 degrees)

2 04 257 (7 of 24 values) 182 (17 of 24 values)

### 29

than 2 percent of hourly wind observations were from the ESE wind direction on all days, including non-exceedance days.

The average PM 10 

### :PM 2.5 

### ratio of all 2007 - 2009 days with valid samples was 6.24 (standard deviation equals 2.89). The ratio observed on January 26, 2008 is near the average for the entire period (5.7), suggesting that ambient PM 10 

### values were caused by emission sources similar to those on other exceedance days.

4 .2.3 May 22, 2008 Exceedance Day Review

Table 15: May 22, 2008 PM 10 

### Concentration: 24-hour value and hourly values disaggregated by southerly wind quadrant.

Figure 6: May 22, 2008 PM 10 

### concentrations and wind speeds compared to average PM 10 

### concentrations and wind speeds from Figure 3.

Compared to the other twenty-eight exceedance days in our data set, May 22, 2008 is the only exceedance day associated with elevated windspeeds, some as high as 17 miles per hour (mph). See Figure 6. Also, the PM 10 

### diurnal pattern for May 22, 2008 is not at all similar to the average of the 26 exceedance days as PM 10 

### concentrations peak around 4:00 pm consistent with the daily high wind speed for the day of 17 mph, and PM 10 

### levels continue to fall with decreasing wind speed. An examination of the wind direction shows

that a ll winds originated from the southerly wind quadrant (135-224 degrees).

The average PM 10 

### :PM 2.5 

### ratio of all 2007 - 2009 days with valid samples was 6.24 (standard deviation equals 2.89). Consistent with the high wind speeds, the ratio observed on May 22, 2008 is the highest in the 2007 - 2009 sample period (10.96), 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0

0 100 200 300 400 500 600 700 800 900 1000Wind Speed (mph)PM10 Concentration PM10 (ug/m3)

Average PM10
SWS (mph)

Average SWS 24

- hour Concentration ( μg/m 3 ) Southerly Wind Quadrant

C oncentration ( μg/m 3 ) (135 to 224 degrees) All Other Wind Direction

Concentration ( μg/m 3 ) (225 to 134 degrees)

21 7 217 (24 of 24 values) No Observed Values

### 30

suggesting that the high late afternoon ambient PM 10 

### values were caused by sources of coarse particulate matter and windblown dust, such as disturbed open areas and unpaved

roads.

4.2.4 January 1, 2009 Exceedance Day Review

Table 16: January 1, 2009 PM 10 

### Concentration: 24-hour value and hourly values disaggregated by southerly wind quadrant.

Figure 7: January 1, 2009 PM 10 

### concentrations and wind speeds compared to average

PM 10 

### concentrations and wind speeds from Figure 3.

As shown above, with higher early morning PM 10 

### concentrations contributing more strongly to the high 24-hour average, the PM 10 

### diurnal pattern for January 1, 2009 varies from the average diurnal pattern for the 26 exceedance days. The diurnal pattern after

mid -day looks similar to other days, with an increase in hourly PM 10 

### concentrations at 6:00 pm; though the increase is less pronounced than the average of other exceedance days. An examination of the hourly PM 10 

### values shows the highest PM 10 

### observations from the southerly wind quadrant from midnight to 4:00 am and in the evening, 8:00- 11:00 pm and very low wind speeds during these timeframes.

The average PM 10 

### :PM 2.5 

### ratio of all 2007 - 2009 days with valid samples was 6.24 (standard deviation equals 2.89). The ratio observed on January 1, 2009 is the second lowest in the 2007 - 2009 sample period (1.67), suggesting that the large early morning

a mbient PM 10 

### values were caused by a combustion source such as residential wood burning, similar to the January 1, 2007 exceedance day. 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0

0 100 200 300 400 500 600 700 800 900 1000Wind Speed (mph)PM10 Concentration PM10 (ug/m3)

Average PM10

SWS (mph)

Average SWS 24

- hour Concentration ( μg/m 3 ) Southerly Wind Quadrant

C oncentration ( μg/m 3 ) (135 to 224 degrees) All Other Wind Direction

Concentration ( μg/m 3 ) (225 to 134 degrees)

2 38 323 (14 of 24 values) 119 (10 of 24 values)

### 31

4.3 Estimate of Expected Exceedance Days “But For” International Transport

Consistent with the Attainment Guidance discussed in Section 2.3, the standard used to

determine attainment of the PM 10 

### NAAQS in the Nogales NAA, “but for” international emissions is as follows: the expected number of days per calendar year with a 24-hour

a verage concentration above 150 μg/m 3 

### must be equal to or less than one. So, to determine that the Nogales NAA has met the PM 10 

### standard “but for” emissions from Mexico, our 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

e mission sources within the Nogales NAA, and that all other monitored exceedances of the NAAQS originate from Mexico.

We used two analyses to estimate the expected exceedance days in the Nogales NAA “but for” international transport. In the first analysis of exceedance days, we estimated the number of exceedances of the NAAQS that would have occurred but for international sources by identifying those exceedance days for which the available information and analyses suggest a significant influence from Mexican emission sources and counting the exceedance days that remain. In our second analysis of hourly concentrations, we classified each hour of the exceedance days based on the likely influence from Mexico and then recalculated a 24-hour average concentration that would have occurred but for international transport of PM 10 

### emissions from Nogales, Sonora. Both analyses are presented below.

4.3.1 Daily Analysis

As discussed in Section 4.1, we have a conceptual model that explains how exceedances

of the PM 10 

### NAAQS occur in the Nogales NAA on 25 of the 29 exceedance days in 2007

- 2009. From our day- by -day review above, we can decide, whether or not, to assign the four remaining exceedance days — January 1, 2007, January 26, 2008, May 22, 2008, and January 1, 2009—to the category of exceedance days having a significant contribution from sources on the Nogales, Sonora side of the international border.

First, the May 22, 2008 exceedance day is wholly different from our conceptual model exceedance day given the relative high windspeeds and higher than usual coarse PM component likely from disturbed surfaces. As with total PM 10 

### emissions, emissions of coarse PM (e.g., unpaved roads) are higher from Nogales, Sonora, than they are from the Nogales NAA. The wind direction is from a southerly quadrant in all hourly observations. Given this information, we find that the 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.

Second, the January 1, 2009 exceedance day is different from our 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

### 32

emissions, emissions of fine PM (e.g., combustion sources) are higher from Nogales, Sonora, than they are from the Nogales NAA. The key factor for assigning this day is the contribution of high hourly ambient concentrations with a southerly wind direction quadrant compared to the remaining 270 degree wind direction quadrants. Consequently,

we find that the 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, too, is different from our 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. What differs in the case of the January 1, 2007 exceedance is that the 270 degree wind direction quadrants contains enough high values to contribute disproportionately to the overall twenty-four hour average concentration. Although more detailed and different field studies might prove otherwise, with the information available, our analysis is inconclusive as to whether this exceedance is attributable to a disproportionate international contribution and the Nogales NAA would not have exceeded the PM 10 

### NAAQS but for emissions from Mexico. It is possible that the PM 10 

### emissions originated south of the U.S.-Mexico border and were blown into the area, but then persisted during periods of calm and variable winds.

Finally, our review of the January 26, 2008 exceedance day suggests that this day is most

li ke our 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 high values in the 17 of 24 hourly observations from the 270 degree wind direction quadrants to be above the 150 g/m 3 

### level. Again, while specifically designed field studies might help adjudicate the relative contributions to this exceedance, with the information available, our analysis is inconclusive as to whether this exceedance is attributable to a disproportionate international contribution and the Nogales NAA would not have exceeded the PM 10 

### NAAQS but fo r emissions from Mexico. It is possible that the PM 10 

### emissions originated south of the U.S.-Mexico border and were blown into the area, but then persisted during periods of calm and

variable winds.

To summarize, we find that two exceedance days, May 22, 2008 and January 1, 2009,

shoul d be categorized with the 25 exceedance days where we have found a high likelihood of a large contribution of PM 10 

### from sources on the Nogales, Sonora side of the international border from the Nogales NAA. The two remaining exceedance days,

J anuary 1, 2007 and January 26, 2008, may have a contribution from sources on the Nogales NAA side of the international border such that we 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. Therefore, using this daily analysis, we find that at least 27 of 29 exceedances of the

PM 10 

### NAAQS observed in the Nogales NAA during 2007 - 2009 can be attributed to

sourc es of PM 10 

### from across the international border. Based on data completeness and

### 33

every day sampling for the 2007 - 2009 timeframe, we calculated a maximum expected

a nnual exceedance rate of 0.7 exceedances per year.

4.3.2 Hourly Analysis

I n our second analysis, we classified each hourly PM 10 

### concentration value from the 29 exceedance days based on the likely influence of emissions from Mexico and then recalculated the 24-hour average concentration that would have occurred but for

int ernational transport of PM 10 

### emissions from Nogales, Sonora. To begin, we classified each hour of the 29 exceedance days based on the likelihood of significant international transport. An hourly concentration was classified as influenced by international transport if it met one of four criteria or decision rules related to hourly observations of wind direction, wind speed, and temperature change:

1) hours with sustained (more than one hour consecutively) southerly winds greater than 4.5 mph (2 meters/second (m/s) ), suggesting the primary influence of windblown dust from across the international border;

2) hours with southerly winds or air flow and decreasing or stable temperatures preceded by or followed by hours with similar conditions, suggesting sustained downslope air flows from higher elevations south of the international border;

3) any hour preceded by and followed by hours with southerly wind or air flow and decreasing or stable temperatures, suggesting continued influence of downslope

air flow from higher elevations south of the international border; and,

4) surface wind speed less than or equal to 1.1 mph (0.5 m/s), preceded by or followed by hours with similar conditions, suggesting sustained air mass stagnation where PM 10 

### emissions suspended in previous hours remain suspended in the stagnant air mass.

The first criterion identifies periods consistent with sustained high winds from the south carrying wind-blown dust, as discussed in Section 4.2.3 concerning the May 22, 2008 exceedance day. The second and third criteria identify periods influenced by downslope wind flow conditions described in the conceptual model as usually occurring in the late afternoon and evening. The fourth criterion identifies 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 begin to increase from their overnight low values.

The analysis of emissions inventories discussed in section 3.2 concluded that U.S. sources are responsible for a maximum of 36 percent of PM 10 

### emissions in the Ambos Nogales region. Therefore, for each hour that meets one of the four criteria listed above, instead of assuming that the concentration is due entirely to Mexican sources, a more conservative assumption is that up to 36 percent of the hourly concentrations may be due to contributions from U.S. emission sources. Therefore, in this next step, we weighted

### 34

the observed hourly concentrations by 0.36 for each hour that meets any one of the four criteria listed above and used this weighted concentration to estimate the 24-hour average concentration that would have occurred in the Nogales NAA but for international
transport.

To show the effects of each decision rule, an estimated 24-hour concentration was calculated after the application of Rule 1, Rules 2 and 3, Rules 1 - 3, and Rules 1 - 4. The

re sults are summarized below. 25



### The application of Rule 1 only removes one day, 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 days, 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 sum, based on this analysis apportioning hourly concentration data using the four criteria to produce an estimated 24-hour average concentration but for international emissions, no exceedance days would have been expected to occur in the Nogales NAA, but for transport from Mexico.

Considering the relatively large differences in emissions inventories between the Nogales NAA and Nogales, Sonora and the meteorology described by our conceptual model, it is likely that observed pollution during southerly downslope wind flows originating from Noga les, Sonora also contributed to observed pollution during following hours of sustained stagnation. With the wind direction varying under low wind speeds and stable temperatures, it remains possible, however, that a greater proportion of PM 10 

### pollution during hours of sustained stagnation may be coming from U.S. sources. Therefore, a slightly more conservative approach would be to relax our criteria by not considering sustained stagnation (Rule 4) and assign PM 10 

### levels during these hours entirely to the Nogales NAA. Consequently, when we consider Mexican influence to only occur under conditions of relative high wind speeds (Rule 1) and sustained downslope wind flows from the south (Rules 2 and 3), two exceedance days would have been expected to occur but for international transport: January 1, 2007 and January 26, 2008. Given the finding that no more than two exceedance days would have occurred applying criteria one

25 The observed concentrations and meteorological data for each hour of each exceedance day, the classification based on the criteria listed above, and the re -calculation of the estimated 24-hour average concentrations but for international transport are provided in Section 3.7 of Analysis of Ambient PM 10 Levels, Topography, and Meteorological Data in Nogales, Arizona: 2007 - 2009 in Appendix C.

### 35

through three, as determined by this hourly analysis of concentration data, the maximum expected number of annual exceedances is 0.7.



## 5.0 Conclusion

A nonattainment area meets the national ambient air quality standard for PM 10 

### when the expected number of days per calendar year with a 24- hour average concentration above 150 μg/m 3 

### are less than or equal to one, based on data completeness and every day

sa mpling. To determine that the Nogales NAA has met the PM 10 

### standard “but for” emissions from Mexico, our analysis must show that no more than three exceedances of the standard in the 2007 - 2009 analysis period would have occurred in the absence of poll utant flows from Mexico.

Using two different analyses to estimate the expected number of exceedance days, we have concluded that no more than two of the exceedance days in 2007 - 2009 would have

oc curred but for transport from Mexican sources. Given that the annual expected exceedance rate, 0.7, is less than or equal to one, we conclude that the Nogales NAA

attains the PM 10 

### NAAQS “but for” PM 10 

### emissions originating from across the

international border.This page is intentionally blank.

### 36



## Appendix A: 2008 and 2011 Emissions Inventory for Nogales NAA

A ppendix B: 2008 and 2011 Emissions Inventory for the Nogales Municipality, Sonora, Mexico

Appendix C: Analysis of Ambient PM 10 

## Levels, Topography, and Meteorological Data in Nogales, Arizona: 2007 – 2009

### 1 

# PM 10 

# Emissions

Inventories for

2008 and 2011

Nogales

Non

- Attainment Area Santa Cruz County, Arizona

U.S. Environmental Protection Agency Region 9

Draft Final, July 20, 2012This page is intentionally blank.

### 2



## Table of Contents

1. Introduction................................................................................................ 3

2. The Nogales Nonattainment Area.......................................................................4

3. Emissions Inventory Methodology......................................................................9

4. 2008 Emissions Inventory and Discussion............................................................12

5. 2011 Emissions Inventory Projection ..................................................................1 4

Appendix 1: MOVES 2008 output file and run specification Appe ndix 2: MOVES 2011 output file and run specification

### 3



## 1. Introduction

1.1 Purpose

This document provides a PM 10 

### emission inventory for all PM 10 

### sources within the Nogales Nonattainment Area (NAA) and the details concerning the derivation of those emissions estimates. The Arizona Department of Environmental Quality (ADEQ) requested that EPA

create this PM 10 

### emissions inventory to support ADEQ’s work on a PM 10 

### State Implementation Plan (SIP) for the Nogales NAA, located in Santa Cruz County, Arizona.

1.2 S ources of PM 10



### PM 10 

### re fers to particulate matter of ten microns or less in aerodynamic diameter. Another class of particles, denoted as PM 2.5 

### , also called fine particulate, refers to particles of 2.5 microns or less in aerodynamic diameter. PM 10 

### includes both PM 2.5 

### and the particulates with aerodynamic

diameter between 2.5 and 10 microns. Sometimes referred to as PM 2.5- 10 

### , this larger fraction is called “coarse” particulate. While fine particles originate mostly from combustion sources and

se condary aerosol generation processes, coarse particles usually originate from mechanical activities and fugitive source categories. Typical major sources of PM 10 

### include fugitive dust, open burning including wild fires, mineral crushing and grinding operations, agricultural activities such as land tilling, dust suspended from vehicle travel on paved and unpaved roads and, to a lesser extent, fuel combustion sources and mobile source exhaust.

1.3 Emissions Inventory Overview

Most of the emissions data for this inventory came from version 1.5 of United States Environmental Protection Agency’s (EPA) 2008 National Emissions Inventory (NEI) for Santa Cruz County, Arizona; any use of other data is noted. EPA prepares the NEI every three years. The NEI is a comprehensive and detailed estimate of air emissions of both criteria and hazardous air pollutants from all air emissions sources and is based primarily on emission estimates and

e mission model inputs provided by state, local, and tribal air agencies for sources in their jurisdi ctions, and supplemented by data developed by the EPA. More information about the

2008 NE I, including methodologies and assumptions used in producing this emissions inventory, may be found at the following URL: http://www.epa.gov/ttn/chief/net/2008inventory.html

.

The NEI allocates emissions at the county level. To develop an inventory for the nonattainment area from the NEI, the county-level emissions estimates must be allocated to the nonattainment area. The methods used for allocating county level emission estimates to the nonattainment area

are described in Section 3 of this document.

### 4



## 2. The Nogales Nonattainment Area

2.1 Overview of the Area

The southern boundary of the Nogales NAA and Santa Cruz County is the U.S./México border.

At the lowe r center of the Nogales NAA, the city of Nogales, Arizona is sixty miles south of

Tuc son, Arizona in the middle and southernmost portion of Santa Cruz County. The city of Noga les, Arizona is the largest city in the nonattainment area. See Figure 1 below.

Regarding topography, the Nogales NAA is located within the Sonoran Desert. This desert

c overs 120,000 square miles with a minimum elevation of 2,500 feet and is in the Basin and Range topographic province. This topography is characterized by north-south elongated valleys surrounded by mountain ranges. Nogales is located in such a north-south valley created by the Noga les Wash running north to the 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 e ast and the Tumacacori, Atascosa, and Pajarito mountains to the west. Approximately 25

mi les to the north are the Santa Rita Mountains and Madera Canyon in the Coronado National

F orest, where Mount Wrightson rises to an elevation of 9,432 feet. Northwest of Interstate 19

a re the Cerro Colorado, Las Guijas, and Sierrita Mountain Ranges.

Major highways in the Nogales, Arizona area are Arizona State Route 82, which connects Nogales, Arizona with Patagonia, Arizona (19 miles) and Sonoita (31 miles) to the northeast, and

U.S. Interstate 19 which connects Tucson, Arizona to Nogales, Arizona and continues south into

Méx ico, where it becomes Federal Highway 15.

Nogales, Sonora, Mexico lies directly south of Nogales, Arizona across the international border.

Ta ken together and referred to as Ambos Nogales, the communities of Nogales, Arizona and Nogales, Sonora, México comprise the largest international border community in Arizona, with a

c ombined population of 232,550 inhabitants in 2010. 1 

### The mean elevation in Nogales, Sonora is 4,265 feet above sea level. 2 

### At 5,380 feet, the highest elevation area in Nogales, Sonora are in the Cerro de los Nogales (Nogales Hill), west of where the Obregón and Colosio routes meet,

ne ar the southern end of the city.

The Alvaro Obregón Boulevard, Luis Donaldo Colosio Boulevard, and the Corredor Fiscal toll road are the main transportation routes in Nogales, Sonora. The Alvaro Obregón Boulevard runs

the le ngth of the narrow Nogales Wash valley, and is a highly congested route used by local and

some c ross-border commercial traffic. The Corredor Fiscal is a toll road for cross-border commercial traffic; its on- and off-ramp access is limited to the border junction at Mariposa Road and a point just outside of the southern ci ty limits of Nogales, Sonora. Th e Corredor Fiscal conducts the majority of the U.S. and Mexico cross-border commercial traffic.

1 Nogales, Arizona had 20,017 inhabitants and Nogales, Sonora, Mexico had 212,533 inhabitants. U.S. Census Bureau 2010 and Instituto Nacional de Estadistica Geografia e Informatica, (INEGI) 2010.

2 “Statistical Municipal Workbook for Nogales, Sonora,” 2005 edition, INEGI.

### 5

Figure 1: Ambos Nogales and Nogales PM 10 

### Nonattainment Area

### 6

2.2 Population and Urbanization

This section presents the population estimates for Santa Cruz County and the Nogales NAA. There are two population centers in Santa Cruz County and the Nogales NAA: the City of Nogales; and, Rio Rico. Only a portion of Rio Rico, however, lies within the Nogales NAA

bounda ries.

2.2.1 Santa Cruz County

In 2010, the U.S. Census estimated the Santa Cruz County population to be 43,716; up 1.45 percent from 43,091 in 2008. 3



### 2.2.2 The City of Nogales, Arizona

In 2010, the U.S. Census estimated the population of Nogales to be 20,837; up 5.49 percent from 19,752 in 2008. 4 

### From 2000 to 2010, the population of Nogales decreased slightly, 0.2 percent; in comparison, the County population grew 13.9 percent. 5



### 2.2. 3 Rio Rico Community

Río Rico is an unincorporated community in Santa Cruz County located twelve miles north of

the U .S./México border and 57 miles south of Tucson. The community resides on 39,000 acres

in the foothills of the Santa Rita Mountains. Eco nomic activities include light manufacturing, and produce staging and distribution in the industrial facilities of the Río Rico South Industrial

P ark.

Because a portion of the Rio Rico community is within the Nogales NAA, we developed an estimate of this population using the U.S. Census and allocation percentages from the Arizona Commerce Authority (ACA). In the 2000 U.S. Census, Río Rico was listed as four Census Designated Places (CDPs): Rio Rico Northeast, Rio Rico Northwest, Rio Rico Southeast, and Rio Rico Southwest. Most of Rio Rico Southeast CDP and a portion of Rio Rico Southwest

C DP are in the Nogales NAA

. Using a Geographic Information System to estimate the Rio Rico land areas within the Nogales NAA, ADEQ determined that 88.7 percent of Rio Rico Southeast and 19.1 percent of Rio Rico Southwest are in the Nogales NAA; the two remaining two Rio

R ico communities are outside of the boundaries of the nonattainment area.

I n 2010, the combined population of the four Rio Rico CDPs was estimated at 18

, 962 inhabitants, but the U.S. Census did not provide a separate population estimate for the four Rio Rico areas (U.S. Census 2010). Prior to the 2010 Census, the ACA provided a population estimate nearly equal to the 2010 Census figure and allocated this estimate across the four Rio Rico areas; we used the percentages derived from the 2010 ACA estimate to allocate the 2010

3 U.S. Census, www.census.gov/popest.

4 Ibid.

5 U.S. Census, www.census.gov/popest ; population figures: Nogales in 2000, 20,878; Nogales in 2010, 20,837; Santa Cruz County in 2000, 38,381; Santa Cruz County in 2010, 43,716.

### 7

U.S. Census figure to the four Rio Rico areas. We then scaled the four area estimates back from 2010 to 2008 assuming the Rio Rico area grew consistent with the 2008 to 2010 Santa Cruz County U.S. Census estimates. Finally, using the land area allocations developed by ADEQ, we estimated population the 2008 contributions from Rio Rico Southeast and Rio Rico Southwest to the Nogales NAA population. Our calculations are shown below in Table 1.

Table 1: 2008 Population Contribution from Rio Rico Communities to the Nogales NAA.

Rio Rico CDP Area 2010

Census 2010 ACA

Estimates 2010 ACA

Allocations 2 010 Census

per ACA

Allocation 2008

Estimate Scaled per County* 2008 Nogales

NAA Contribution

Northeast

- 4,921 26 percent 4,912 4, 841 Area outside NAA

Northwest

- 5,408 28 percent 5,398 5, 320 Area outside NAA

Southeast

- 3,439 18 percent 3,433 3,3 83 3,001

Southwest

- 5,228 28 percent 5,219 5, 143 9 8 2

Totals 18,962 18,996 100 percent 18,962 18, 687 3,983 * Santa Cruz County grew 1.45 percent from 2008 to 2010; figures are reduced accordingly

. Source: U.S. Census, www.census.gov/popest



### 2.3 Land-Areas of Santa Cruz County and the Nogales NAA

Santa Cruz County compris es 1,23 7.6 square miles of land, or approximately 791,632 acres. 6


### The majority of land ownership in Santa Cruz County is distributed between the U.S. Forest Service (52.7 percent), private land-owners (37.6 percent), State of Arizona Trust Land (7.8

pe rcent), and the U.S. Bureau of Land Management (1.7 percent). 7 

### See Figure 2 below.

The Nogales NAA covers a land area of 76.1 square miles. 8 

### In comparison with the County, the majority of the land in the nonattainment area is privately owned. The codified boundaries of the Nogales NAA can be found at 40 CFR Part 81.303. The Nogales PM 10 

### non attainment area is delineated by the following townships and ranges within the State of Arizona that lie east of 111

d egrees longitude: T23S, R13E; T23S, R14E; T24S, R13E; and, T24S, R14E.

6 U.S. Census, Santa Cruz County Quickfacts, http://quickfacts.census.gov/qfd/states/04/04023.html

7 Arizona State Land Department, Arizona Land Resource Information System (1994)

8 EPA Geographic Information System estimate.

### 8

Figure 2: Santa Cruz County Land Ownership and Nogales PM 10 

### Nonattainment Area.

### 9



## 3. Emissions Inventory Methodology

3.1 EPA ’s 2008 National Emissions Inventory

This Nog ales NAA emissions inventory is based on modifications to version 1.5 of EPA’s 2008 National Emission Inventory (NEI). EPA's NEI database contains information about sources that emit criteria air pollutants and their precursors, and hazardous air pollutants. The database includes estimates of annual air pollutant emissions from point, nonpoint, and mobile sources in the fifty states, the District of Columbia, Puerto Rico, and the Virgin Islands available at the county level. Collaborating with the states, EPA develops the emissions inventory and releases an updated version of the NEI database every three years.

Five of the six criteria air pollutants are included in the NEI database. Emissions of carbon monoxide (CO), nitrogen oxides (NOx), sulfur dioxide (SO2), lead (Pb), and particulate matter (PM 10 

### and PM 2.5 

### ) are specifically reported in the NEI. Ozone, the sixth criteria air pollutant,

a rises from photochemical reactions in the atmosphere rather than direct emissions from sources.

EPA compiled the NEI database from the primary data sources listed below: emissions inventories compiled by state and local environmental agencies;

d atabases related to EPA's Maximum Achievable Control Technology (MACT) programs to reduce emissions of hazardous air pollutants; Toxic Release Inventory (TRI) data; for electric generating units, EPA's Emission Tracking System / Continuous Emissions Monitoring data (ETS/CEM) and Department of Energy fuel use data;

for on -road sources, the Federal Highway Administration's estimate of vehicle miles

traveled and emission factors from EPA's MO VES2030a computer model ; for non -road sources, EPA's NONROAD2008a computer model; and,

p revious emissions inventories, if states do not submit current data.

A complete description of the development of the 2008 NEI may be found at the following URL: http://www.epa.gov/ttn/chief/net/2008inventory.html

.

3.2 On-Road Mobile Source Emissions

In the 2008 NEI, on-road mobile source emissions were calculated using EPA’s MOBILE6

model. S ince the 2008 NEI was developed, EPA’s MOVES model has replaced MOBILE6 as the model for estimating emissions from cars, trucks, and motorcycles. 9 

### On March 2, 2010, EPA approved the availability of the Motor Vehicle Emissions Simulator model (MOVES2010a) in official SIP submissions to EPA regarding air quality and for certain transportation conformity

a nalyses outside the state of California. 10 

### MOVES2010a is the state-of-the-art upgrade to EPA’s modeling tools for estimating air emissions from cars, trucks, motorcycles, and buses, and is

b ased on analys es of millions of emission test results and considerable advances in the Agency’s

9 http://www.epa.gov/otaq/models/moves/index.htm

10 See 75 FR 9411 (March 2, 2010)

### 10

understanding of vehicle emissions. MOVES2010a was designed to replace the previous

e missions model, MOBILE6.2, which was released in 2004.

3.2.1 Calculating Santa Cruz County PM 10 

### Emissions Using MOVES.

EPA calculated the PM 10 

### emissions from mobile sources in Santa Cruz County, Arizona using the MOVES2010a version dated September 23, 2010 (hereafter referred to as “MOVES”). This

is t he current version of the MOVES model. MOVES allows the use of county-specific data

c oncerning factors such as the average speed distribution of on-road vehicles, daily vehicles miles traveled, and road types among others in place of national default values. The MOVES

model r equires the use of county specific data for SIP purposes. In this instance, the MOVES calculation was performed usin g input data from the 2008 NEI for Santa Cruz County.

With the county-specific data in place, EPA prepared a run specification to identify the characteristics of a MOVES model run such as: scale, time span, vehicle and road type, and pollutants. The run specifications used for the 2008 and 2011 PM 10 

### calculations can be found in Appe ndi ces 1 and 2

. Based on the run specification, MOVES produces various summaries and output tables in MySQL format. The MySQL database can then be used to import the MOVES output into a variety of formats. In this instance, EPA staff used MySQL to produce the PM 10 

### calculation in an Excel spreadsheet format; the resulting 2008 and 2011 output files are reproduced in tables within Appendices 1 and 2.

3.3 Allocating the Santa Cruz County PM 10 

### Emissions to the Nogales NAA

EPA ha s no guidance on assigning emission sources from a county level of analysis to a smaller subject area within that county. For the Nogales NAA emissions inventory, EPA used a combination of population ratios, land area ratios, and source locations within the Nogales NAA

to dete rmine the appropriate allocation of county-wide emissions to the Nogales NAA.

3.3. 1 Emissions Scaling Based on Population

One way to allocate emissions from a county-level to a smaller nonattainment area is to scale

those e missions by a population ratio. In some cases, it is logical to scale source categories by population, since the rate of activities causing the emissions is more closely related to the number of people than to other factors, such as a specific land area relationship.

As shown a

bove, EPA used data from the U.S. Census Bureau was used to estimate the 2008 population of the Nogales NAA population and Santa Cruz County. There are two assumptions underlying these calculations: first, we assume that the City of Nogales and the allocated population of Ri o Rico comprise nearly all of the population within the nonattainment area. The

re mainder of the Nogales NAA is assumed to be rural and minimally populated. Second, as described in section 2.2.3, the individual 2008 Rio Rico area populations were allocated using 2010 estimates from ACA and scaled back to 2008 according to the U.S. Census derived County-wide 2008 to 2010 growth rate.

### 11

When allocating emissions based on population, the county-level emissions for a given source category were multiplied by a factor of 55.1 percent to give the respective source category emissions for the Nogales NAA. See Table 2 below. If the likely magnitude of source category emissions varied with the activities of the population, it was allocated based on this population

ratio.

Table 2: Summary of Santa Cruz County and Nogales NAA Population Data

Census Area 2008 2008 Percent of County 2010 2010 Percent of County

Santa Cruz County 4 3,091 43,7 16 City of Nogales 19, 752 4 5.8 % 20, 837 4 7 .7 %
Rio Rico ( allocated value from Table 1 ) 3,9 83 9.2 % 4,042 9.2 %
Nogales NAA totals 23, 735 55. 1% 24,059 5 6.9%

Source: 2010 U.S. Census and www.census.gov/popest



### The population estimates for Nogales are from the following U.S. Census Bureau population

sourc e: http://www.census.gov/popest

.

3.3.2 Emissions Scaling Based on Land Area

A l and area weighted emission ratio was developed using U.S. Census geographic data and/or Arizona Commerce Authority data. 11 

### The land area for Santa Cruz County is 1,237.6 square

mi les. The land area for the Nogales NAA is 76.1 square miles. The ratio of Nogales NAA land

a rea to the Santa Cruz County land area is calculated by dividing 76.1 b y 1,237.6, which equals

.061489 or

6.15 percent.

For a spatial allocation of county-level emissions to the nonattainment area based on weighting by land area, the coun ty

- level emissions were multiplied by 6.15 percent to give the emissions for the Nogales NAA. Some source categories, such as agricultural emissions, are likely to be proportional to land area; consequently, they are logically allocated by the land area ratio.

3.3.3 Source Emissions Identification Within the Nogales NAA.

To confirm whether specific sources in the Santa Cruz County emissions inventory should be included in the Nogales NAA inventory, EPA used visual inspections with location information, such as satellite photography using Google Earth. Also, EPA consulted with ADEQ.

3.4 Summary of Land Area and Population Allocation Ratios

Table 3: Summary of Land Area and 2008 Population Allocation Ratios.

Santa Cruz County Nogales NAA Allocatio n Ratio Area (square miles) 1,237.6 12 76.1 6.15 percent 2008 Population 4 3,091 13 23, 735 14 55. 1 percent

11 Arizona Department of Commerce Profile: Santa Cruz County Arizona, May 10, 2011, http://www.azcommerce.com/doclib/commune/Santa Cruzpercent20county.pdf

. 12 U.S. Census, Quickfacts, Santa Cruz County, Arizona.

13 2010 U.S. Census population estimates.

### 12



## 4. 2008 Emissions Inventory and Discussion

The Santa Cruz County emissions inventory and Nogales NAA allocation results are shown in Table 4. We discuss specific issues concerning the allocated emissions inventory in the sections following Table 4.

Table 4: Santa Cruz County and Nogales NAA 2008 PM

- 10 Emissions Inventories (tons).

Emissions Source Category Santa Cruz County Nogales

NAA Allocation

Method
Agriculture

- Crops and Livestock Dust 70.47 4.33 Area
Commercial Cooking

- Charbroiling 11.36 6.26 Pop Commercial Cooking

- Frying 2.82 1.55 Pop

Dust

- Paved Road Dust 220.39 121.43 Pop

Dust

- Unpaved Road Dust 1

, 569.74 864.93 Pop

Dust

- Road Construction 484.52 266.97 Pop

Dust

- Commercial/Industrial/Institutional Construction 258.75 142.57 Pop

Dust

- Residential Construction 43.45 23.94 Pop

Fires

- Prescribed Fires 54.93 3.38 Area

Fuel Comb ustion

- Electric Generation

- Natural Gas 1.05 1.05 Loc

Fuel Comb ustion

- Electric Generation

- Oil 0.04 0.02 Pop

Fuel Comb ustion

- Industrial Boilers, ICEs

- Natural Gas 0.25 0.14 Pop

Fuel Comb ustion

- Industrial Boilers, ICEs

- Oil 1.04 0.57 Pop

Fuel Comb ustion

- Industrial Boilers, ICEs

- Coal

--- --- See Section 4.1

Fuel Comb ustion

- Residential

- Wood 43.55 23.99 Pop

Fuel Comb ustion

- Residential

- Natural Gas, Oil, Other 1.51 0.83 Pop

Fuel Comb ustion

- Comm ercial /Institutional

- Oil 0.29 0.16 Pop

Fuel Comb ustion

- Comm ercial /Institutional

- Natural Gas 0.72 0.40 Pop

Fuel Comb ustion

- Comm ercial /Institutional

- Coal 0.04 0.02 Pop

Fuel Comb ustion

- Comm ercial /Institutional

- Other 0.02 0.01 Pop

Industrial Processes

- Mining

--- --- See Section 4.1

Mobile

- Gasoline Vehicle

- Off net roadway s 1 .22 0. 67 Pop

Mobile

- Gasoline Vehicle

- Rural restricted access roads 1 .76 0. 97 Pop

Mobile

- Gasoline Vehicle

- Rural unrestricted access roads 2.59 1.43 Pop

Mobile

- Gasoline Vehicle

- Urban restricted access 1.33 0. 73 Pop

Mobile

- Gasoline Vehicle

- Urban unrestricted access 8.37 4.61 Pop

Mobile

- Diesel Vehicle

- Off network road ways 1 .1 0.61 Pop

Mobile

- Diesel Vehicle

- Rural restricted access roads 13.16 7.25 Pop

Mobile

- Diesel Vehicle

- Rural unrestricted access roads 5 .51 3.04 Pop

Mobile

- Diesel Vehicle

- Urban restricted access 3.24 1.79 Pop

Mobile

- Diesel Vehicle

- Urban unrestricted access 1 2.15 6.69 Pop

Mobile

- Non

- Road Equipment

- Diesel 15.48 8.53 Pop

14 Ibid.

### 13

Mobile

- Non

- Road Equipment

- Gasoline 5.66 3.12 Pop

Mobile

- Non

- Road Equipment

- Other 0.13 0.07 Pop

Mobile

- Locomotives 1.70 0.63 Loc

Mobile

- Aircraft 2.31 2.31 Loc

Waste Disposal

- Residential Garbage Burning 41.77 23.02 Pop Waste Disposal

- Open Burning for Land Clearing 24.23 1.49 Area
Waste Disposal

- Residential Yard Waste Burning 1.21 0.67 Pop Waste Disposal

- Institutional Incineration 0.28 0.28 Loc

Miscellaneous Non

- Industrial NEC 0.44 0.24 Pop

TOTALS 2,908.58 1 ,530.7 Allocation method: Area = Land area ratio; Loc = Location; Pop = Population ratio.



### 4.1 Sources with Reported Locations

There are inventory source categories that include sources with known locations. Since the location and emission rates for these sources are known, it is possible to determine if the sources are inside or outside the nonattainment area using mapping software. These source categories are

discussed below.

Fuel Combustion - Electric Generation - Natural Gas. A power plant, Valencia Power, is

located within the nonattainment area. Fuel Combustion - Industrial Boilers, ICEs – Coal, 11.68 tons per year. Upon consulting

with ADE Q about the source of these emissions entry, we were informed that this county-wide entry was an error and ADEQ will work with EPA to correct the 2008 NEI data. Consequently, these emissions were not included in the non-attainment area

estimates.

Industrial Processes – Mining, 761.11 tons per year. Upon consulting with ADEQ about the source of these emissions, we were informed that this county-wide entry was an error and ADEQ will work with EPA to correct the 2008 NEI data. Consequently, these

emissions were not included in the non-attainment area estimates.

Mobile – Aircraft. The only airport in the County, Nogales International Airport, is

within the nonattainment area.

Mobile – Locomotives. An estimated 11.0 of 29.8 miles of County rail track are within the nonattainment area; consequently, county-wide locomotive emissions were allocated by a 0.369 ratio. Waste Disposal - Institutional Incineration. A medical waste incinerator is located within

the nonattainment area.

4.2. Assessment of Emissions Estimates

The 2008 estimated rate of PM 10 

### emissions from road and other construction may be high because the emissions estimate does not reflect the full magnitude of the downturn in the real estate sector of the economy. It is likely that this downturn is a temporary situation and it may be expected that these emissions would resume at a higher level than once the real estate

### 14

economy improves. As a result, this emission rate is conservative and is based on the best estimates of construction activity available at this time.

Also, the EPA could not identify locations of agricultural activities, prescribed forest burning, raising a source of uncertainty. While it is appropriate to apply a land ratio method for assigning

C ounty-level agricultural emissions to the nonattainment area, this may underestimate emissions given that intensive agricultural activity is likely to occur on private land, located primarily in the nonattainment area, as opposed to the public lands composing a large proportion of the remaining County.

4. 3 Overall Assessment

The NEI provides a complete, timely and sufficiently accurate inventory for Santa Cruz County based on the best methodology and source data available at the time the inventory was developed. In allocating these County-wide emissions to the Nogales NAA, EPA has used reasonable and conservative assumptions to produce a current, accurate, and comprehensive

nonattainment area PM 10 

### emissions inventory.



## 5. 2011 Emissions Inventory Projection

5.1 Overview

Because 2008 is the year of the most current and complete national emissions inventory, we chose it as the base year for the emissions inventory and the Nogales PM 10 

### attainment plan. Unfortunately, the Nogales NAA did not meet the PM 10 

### NAAQS in 2008. It becomes important that the attainment plan characterize future emissions levels as part determining whether or where future controls may be needed to meet the PM 10 

### NA AQS. Consequently, we have provided an emissions inventory for the year 2011.

5.2 Methodology for Projecting the 2011 Emissions Inventory

PM 10 

### emissions may rise or fall based on changes in three factors: economic conditions, population, and vehicle miles traveled (VMT). The accepted method for projecting emissions from base year inventories is to account for changes in these three factors as they may apply on a source sector basis. Below, we review each of these factors and their application to our 2008 base year inventory.

Considering economic conditions, there is an ongoing economic contraction in Arizona that began in 2007 and is projected to continue through 2011. Non-farm employment is projected to continue dropping through 2010 and 2011 according to the Economic and Business Research Center at the University of Arizona. 15

15 http://ebr.eller.arizona.edu/dataentry/forecast.aspx.

### 15

The U.S. Census has calculated moderate population growth overall in Santa Cruz County, from 43,091 in 2008 to 43,716 in 2010. 16 

### Extrapolating this trend yields an estimated population increase of about 2.18 percent for the County from 2008 to 2011. The Nogales NAA appears to have grown faster than the County from 2008 to 2010, at 4.82 percent; so, its estimated increase from 2008 to 2011 is higher at 7.23 percent. While it may look like the Nogales NAA is growing precipitously, recall that the City of Nogales’s population decreased 0.2 percent between 2000 and 2010. A review of 2000-2010 City of Nogales population estimates shows slightly falling estimates after 2002, a large decrease in 2007, the lowest population estimate occurring in 2008, and a subsequent rebound through 2010. Given that we are only forecasting one year beyond 2010 census figures and most 2008-2011 population growth as already occurred, we are using the 7.23 percent growth factor to reflect actual population estimates for the 2008-11 period.

Regarding VMT, the Federal Highway Administration's Highway Statistics 17 

### series data on Arizona shows a decline in VMT between 2007 and 2008 and no change in VMT between 2008

a nd 2009. This is consistent with economic conditions. Given a continuing or slowing economic contraction, there doesn't appear to be a reason to assume that VMT will increase within Santa Cruz County. EPA estimates for 2011 show a slight decrease in VMT.

In summary, for our projection methodology and the 2011 emission inventory, we will assume the following: source categories tied to economic activity will not grow between 2008 and 2011; source categories that track with population growth will be estimated at the same rate as the Nogales NAA population growth, as opposed to the County growth rate, to reflect reported population change and to be conservative in estimating emissions; and,

on -road mobile source will be estimated as discussed below.

PM 10 

### emissions from on-road mobile sources fall into four categories: brake and tire wear, vehicle exhaust, paved road dust, and unpaved road dust. As old on-road vehicles are replaced with newer, cleaner vehicles, exhaust emissions are expected to go down. Also, changes to cleaner fuel specifications lead to lower exhaust emissions. The overall changes in vehicle exhaust emissions are captured in the EPA MOVES emission model. MOVES also produces emissions estimates for brake and tire wear. EPA ran the MOVES model for 2011 to produce

C ounty-wide estimates for exhaust, brake, and tire-wear. Then, EPA scaled these emissions by the non-attainment area population ratio to estimate the 2011 emissions for these source categories. To be conservative and to reflect 2010 Census figures, we used a 0.569 ratio instead

of the 0.551 ratio used for 2008 population based allocations.

Other on-road PM 10 

### emissions, such as paved and unpaved road emissions, do not vary with changes in the age of the vehicle fleet or changes in fuel. These emissions are affected primarily by VMT and local factors, such as dust loading on paved roads. This projection has estimated conservatively that these emissions will be constant from 2008 to 2011, despite a smal l anticipated decrease in VMT.

16 http://www.census.gov/popest/eval-estimates/eval-est2010.html.

17 http://www.fhwa.dot.gov/policyinformation/statistics.cfm.

### 16

5

. 3 2011 Emissions Inventory

The 2011 emissions inventory results are shown in the table below.

Table 5: Nogales NAA PM 10 

### Emissions Inventories for 2008 and 2011 (tons per year).

Emissions Source Category 2008 2011 Projection

Method
Agriculture

- Crops and Livestock Dust 4.33 4.33 No growth
Commercial Cooking

- Charbroiling 6.26 6.71 Population
Commercial Cooking

- Frying 1.55 1.67 Population

Dust

- Paved Road Dust 121.43 121.43 No growth

Dust

- Unpaved Road Dust 864.93 864.93 No growth

Dust

- Road Construction 266.97 266.97 No growth

Dust

- Commercial/Industrial/Institutional Construction 142.57 142.57 No growth

Dust

- Residential Construction 23.94 23.94 No growth

Fires

- Prescribed Fires 3.38 3.38 No growth

Fuel Comb

- Electric Generation

- Natural Gas 1.05 1.05 No growth

Fuel Comb

- Electric Generation

- Oil 0.02 0.02 No growth

Fuel Comb

- Industrial Boilers, ICEs

- Natural Gas 0.14 0.14 No growth

Fuel Comb

- Industrial Boilers, ICEs

- Oil 0.57 0.57 No growth

Fuel Comb

- Residential

- Wood 23.99 25.73 Population

Fuel Comb

- Residential

- Natural Gas, Oil, Other 0.83 0.89 Population

Fuel Comb

- Comm ercial /Institutional

- Oil 0.16 0.16 No growth

Fuel Comb

- Comm ercial /Institutional

- Natural Gas 0.40 0.40 No growth

Fuel Comb

- Comm ercial /Institutional

- Coal 0.02 0.02 No growth

Fuel Comb

– Comm ercial /Institutional

- Other 0.01 0.01 No growth

Mobile

- Gasoline Vehicle

- Off net roadway 0. 67 0.56 MOVES

Mobile

- Gasoline Vehicle

- Rural restricted access roads 0. 97 0. 84 MOVES

Mobile

- Gasoline Vehicle

- Rural unrestricted access roads 1.43 1.33 MOVES

Mobile

- Gasoline Vehicle

- Urban restricted access 0. 73 0. 6 7 MOVES

Mobile

- Gasoline Vehicle

- Urban unrestricted access 4.61 4.47 MOVES

Mobile

- Diesel Vehicle

- Off network roads 0.61 0.40 MOVES

Mobile

- Diesel Vehicle

- Rural restricted access roads 7.25 4. 73 MOVES

Mobile

- Diesel Vehicle

- Rural unrestricted access roads 3.04 2.09 MOVES

Mobile

- Diesel Vehicle

- Urban restricted access 1.79 1. 22 MOVES

Mobile

- Diesel Vehicle

- Urban unrestricted access 6.69 4.72 MOVES

Mobile

- Non

- Road Equipment

- Diesel 8.53 8.53 No growth

### 17

Mobile

- Non

- Road Equipment

- Gasoline 3.12 3.12 No growth

Mobile

- Non

- Road Equipment

- Other 0.07 0.07 No growth

Mobile

- Locomotives 0.63 0.63 No growth

Mobile

- Aircraft 2.31 2.31 No growth

Waste Disposal

- Residential Garbage Burning 23.02 24.68 Population
Waste Disposal

- Open Burning for Land Clearing 1.49 1.60 Population
Waste Disposal

- Residential Yard Waste Burning 0.67 0.71 Population
Waste Disposal

- Institutional Incineration 0.28 0.30 Population

Miscellaneous Non

- Industrial NEC 0.24 0.26 Population

TOTALS 1 ,530.7 1 ,528.16



### 5.4 Assessment of 2011 Inventory

Population growth is relatively small, keeping those increases in emissions to a minimum. Thelack of economic growth also retards emissions inventory growth. There is a notable drop in onroad emissions due to fleet turnover and new fuel standards. There is, however, little overall

c hange between the 2008 and 2011 emissions inventories.

### 18



## Appendix 1: MOVES 2008 Output File and Run Specification

Output File: Definitions and Values

Category

Field Value Description

State ID 4 ARIZONA

County ID 4023 Santa Cruz County

Fuel Type ID 1 Gasoline

Fuel Type ID 2 Diesel Fuel

Road Type ID 1 Off

- Network

Road Type ID 2 Rural Restricted Access

Road Type ID 3 Rural Unrestricted Access

Road Type ID 4 Urban Restricted Access

Road Type ID 5 Urban Unrestricted Access



### Output File: PM-10 Total and Break Out by Fuel and Roadway Type (units in pounds)

Fuel Road Run Total

PM10 Brake

PM10 Elemental

Carbon

PM10 Organic

Carbon

PM10 Sulfate

PM10 Tire

PM10

1 1 1 2440 0 814 1627 0 0

1 2 1 2465 293 306 2159 0 757

1 3 1 1774 2171 218 1556 0 1228

1 4 1 1194 959 152 1042 0 500

1 5 1 3445 10449 437 3008 0 2848

2 1 1 2202 0 605 1597 0 0

2 2 1 25301 439 22555 2746 0 576

2 3 1 10053 681 7867 2187 0 281

2 4 1 5795 542 4565 1230 0 146

2 5 1 20558 3232 15062 5496 0 504

Totals 75227 18766 52581 22648 0 6840

### 19

Output File: Energy and Distance by Fuel and Roadway Type (units in MMBtu and miles)

Fuel Road Run Total Energy Distance

1 1 1 85644

1 2 1 482862 91817600

1 3 1 530307 103452000

1 4 1 238446 44182600

1 5 1 1135807 183604000

2 1 1 31765

2 2 1 494200 22257900

2 3 1 161149 9007850

2 4 1 93611 4440350

2 5 1 275949 12298100

Totals 3529740 471060400



### MOVES 2008 Run Specification

<runspec> <description><![CDATA[2008 Santa Cruz County AZ]]></description>

<modelscale value="Inv"/>

<modeldomain value="SINGLE"/> <geographicselections> <geographicselection type="COUNTY" key="4023" description="ARIZONA - Santa Cruz County"/> </geographicselections> <timespan> <year key="2008"/>

<month id="1"/>

<month id="2"/>

<month id="3"/>

<month id="4"/>

<month id="5"/>

<month id="6"/>

<month id="7"/>

<month id="8"/>

<month id="9"/>

<month id="10"/>

<month id="11"/>

<month id="12"/> <day id="2"/> <day id="5"/> <beginhour id="1"/>

<endhour id="24"/> <aggregateBy key="Year"/> </timespan>

<onroadvehicleselections> <onroadvehicleselection fueltypeid="2" fueltypedesc="Diesel Fuel" sourcetypeid="62" sourcetypename="Combination Long-haul Truck"/> <onroadvehicleselection fueltypeid="2" fueltypedesc="Diesel Fuel" sourcetypeid="61" sourcetypename="Combination Short-haul Truck"/>

### 20 <onroadvehicleselection fueltypeid="2" fueltypedesc="Diesel Fuel" sourcetypeid="41" sourcetypename="Intercity Bus"/> <onroadvehicleselection fueltypeid="2" fueltypedesc="Diesel Fuel" sourcetypeid="32" sourcetypename="Light Commercial Truck"/> <onroadvehicleselection fueltypeid="2" fueltypedesc="Diesel Fuel" sourcetypeid="54" sourcetypename="Motor Home"/> <onroadvehicleselection fueltypeid="2" fueltypedesc="Diesel Fuel" sourcetypeid="11" sourcetypename="Motorcycle"/> <onroadvehicleselection fueltypeid="2" fueltypedesc="Diesel Fuel" sourcetypeid="21" sourcetypename="Passenger Car"/> <onroadvehicleselection fueltypeid="2" fueltypedesc="Diesel Fuel" sourcetypeid="31" sourcetypename="Passenger Truck"/> <onroadvehicleselection fueltypeid="2" fueltypedesc="Diesel Fuel" sourcetypeid="51" sourcetypename="Refuse Truck"/> <onroadvehicleselection fueltypeid="2" fueltypedesc="Diesel Fuel" sourcetypeid="43" sourcetypename="School Bus"/> <onroadvehicleselection fueltypeid="2" fueltypedesc="Diesel Fuel" sourcetypeid="53" sourcetypename="Single Unit Long-haul Truck"/> <onroadvehicleselection fueltypeid="2" fueltypedesc="Diesel Fuel" sourcetypeid="52" sourcetypename="Single Unit Short-haul Truck"/> <onroadvehicleselection fueltypeid="2" fueltypedesc="Diesel Fuel" sourcetypeid="42" sourcetypename="Transit Bus"/> <onroadvehicleselection fueltypeid="1" fueltypedesc="Gasoline" sourcetypeid="62" sourcetypename="Combination Long-haul Truck"/> <onroadvehicleselection fueltypeid="1" fueltypedesc="Gasoline" sourcetypeid="61" sourcetypename="Combination Short-haul Truck"/> <onroadvehicleselection fueltypeid="1" fueltypedesc="Gasoline" sourcetypeid="41" sourcetypename="Intercity Bus"/> <onroadvehicleselection fueltypeid="1" fueltypedesc="Gasoline" sourcetypeid="32" sourcetypename="Light Commercial Truck"/> <onroadvehicleselection fueltypeid="1" fueltypedesc="Gasoline" sourcetypeid="54" sourcetypename="Motor Home"/> <onroadvehicleselection fueltypeid="1" fueltypedesc="Gasoline" sourcetypeid="11" sourcetypename="Motorcycle"/> <onroadvehicleselection fueltypeid="1" fueltypedesc="Gasoline" sourcetypeid="21" sourcetypename="Passenger Car"/> <onroadvehicleselection fueltypeid="1" fueltypedesc="Gasoline" sourcetypeid="31" sourcetypename="Passenger Truck"/> <onroadvehicleselection fueltypeid="1" fueltypedesc="Gasoline" sourcetypeid="51" sourcetypename="Refuse Truck"/> <onroadvehicleselection fueltypeid="1" fueltypedesc="Gasoline" sourcetypeid="43" sourcetypename="School Bus"/> <onroadvehicleselection fueltypeid="1" fueltypedesc="Gasoline" sourcetypeid="53" sourcetypename="Single Unit Long-haul Truck"/> <onroadvehicleselection fueltypeid="1" fueltypedesc="Gasoline" sourcetypeid="52" sourcetypename="Single Unit Short-haul Truck"/> <onroadvehicleselection fueltypeid="1" fueltypedesc="Gasoline" sourcetypeid="42"

so urcetypename="Transit Bus"/>

</onroadvehicleselections>

<offroadvehicleselections>

</offroadvehicleselections>

<offroadvehiclesccs>

</offroadvehiclesccs> <roadtypes> <roadtype roadtypeid="1" roadtypename="Off-Network"/> <roadtype roadtypeid="2" roadtypename="Rural Restricted Access"/>

### 21 <roadtype roadtypeid="3" roadtypename="Rural Unrestricted Access"/> <roadtype roadtypeid="4" roadtypename="Urban Restricted Access"/> <roadtype roadtypeid="5" roadtypename="Urban Unrestricted Access"/> </roadtypes> <pollutantprocessassociations> <pollutantprocessassociation pollutantkey="100" pollutantname="Primary Exhaust PM10 - Total" processkey="1" processname="Running Exhaust"/> <pollutantprocessassociation pollutantkey="100" pollutantname="Primary Exhaust PM10 - Total" processkey="2" processname="Start Exhaust"/> <pollutantprocessassociation pollutantkey="100" pollutantname="Primary Exhaust PM10 - Total" processkey="15" processname="Crankcase Running Exhaust"/> <pollutantprocessassociation pollutantkey="100" pollutantname="Primary Exhaust PM10 - Total" processkey="16" processname="Crankcase Start Exhaust"/> <pollutantprocessassociation pollutantkey="100" pollutantname="Primary Exhaust PM10 - Total" processkey="17" processname="Crankcase Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="100" pollutantname="Primary Exhaust PM10 - Total" processkey="90" processname="Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="106" pollutantname="Primary PM10 - Brakewear Particulate" processkey="9" processname="Brakewear"/> <pollutantprocessassociation pollutantkey="102" pollutantname="Primary PM10 - Elemental Carbon" processkey="1" processname="Running Exhaust"/> <pollutantprocessassociation pollutantkey="102" pollutantname="Primary PM10 - Elemental Carbon" processkey="2" processname="Start Exhaust"/> <pollutantprocessassociation pollutantkey="102" pollutantname="Primary PM10 - Elemental Carbon" processkey="15" processname="Crankcase Running Exhaust"/> <pollutantprocessassociation pollutantkey="102" pollutantname="Primary PM10 - Elemental Carbon" processkey="16" processname="Crankcase Start Exhaust"/> <pollutantprocessassociation pollutantkey="102" pollutantname="Primary PM10 - Elemental Carbon" processkey="17" processname="Crankcase Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="102" pollutantname="Primary PM10 - Elemental Carbon" processkey="90" processname="Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="101" pollutantname="Primary PM10 - Organic Carbon" processkey="1" processname="Running Exhaust"/> <pollutantprocessassociation pollutantkey="101" pollutantname="Primary PM10 - Organic Carbon" processkey="2" processname="Start Exhaust"/> <pollutantprocessassociation pollutantkey="101" pollutantname="Primary PM10 - Organic Carbon" processkey="15" processname="Crankcase Running Exhaust"/> <pollutantprocessassociation pollutantkey="101" pollutantname="Primary PM10 - Organic Carbon" processkey="16" processname="Crankcase Start Exhaust"/> <pollutantprocessassociation pollutantkey="101" pollutantname="Primary PM10 - Organic Carbon" processkey="17" processname="Crankcase Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="101" pollutantname="Primary PM10 - Organic Carbon" processkey="90" processname="Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="105" pollutantname="Primary PM10 - Sulfate Particulate" processkey="1" processname="Running Exhaust"/> <pollutantprocessassociation pollutantkey="105" pollutantname="Primary PM10 - Sulfate Particulate" processkey="2" processname="Start Exhaust"/> <pollutantprocessassociation pollutantkey="105" pollutantname="Primary PM10 - Sulfate Particulate" processkey="15" processname="Crankcase Running Exhaust"/> <pollutantprocessassociation pollutantkey="105" pollutantname="Primary PM10 - Sulfate Particulate" processkey="16" processname="Crankcase Start Exhaust"/> <pollutantprocessassociation pollutantkey="105" pollutantname="Primary PM10 - Sulfate Particulate" processkey="17" processname="Crankcase Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="105" pollutantname="Primary PM10 - Sulfate Particulate" processkey="90" processname="Extended Idle Exhaust"/>

### 22 <pollutantprocessassociation pollutantkey="107" pollutantname="Primary PM10 - Tirewear Particulate" processkey="10" processname="Tirewear"/> <pollutantprocessassociation pollutantkey="116" pollutantname="Primary PM2.5 - Brakewear Particulate" processkey="9" processname="Brakewear"/> <pollutantprocessassociation pollutantkey="117" pollutantname="Primary PM2.5 - Tirewear Particulate" processkey="10" processname="Tirewear"/> <pollutantprocessassociation pollutantkey="91" pollutantname="Total Energy Consumption" processkey="1" processname="Running Exhaust"/> <pollutantprocessassociation pollutantkey="91" pollutantname="Total Energy Consumption" processkey="2" processname="Start Exhaust"/> <pollutantprocessassociation pollutantkey="91" pollutantname="Total Energy Consumption" processkey="90" processname="Extended Idle Exhaust"/> </pollutantprocessassociations>

<databaseselections> <databaseselection servername="" databasename="c04023y2008_in20110329" description=""/>

</databaseselections> <internalcontrolstrategies> <internalcontrolstrategy classname="gov.epa.otaq.moves.master.implementation.ghg.internalcontrolstrategies.rateofprogress.RateO fProgressStrategy"><![CDATA[

useParameters No

]]></internalcontrolstrategy> </internalcontrolstrategies> <inputdatabase servername="" databasename="" description=""/> <uncertaintyparameters uncertaintymodeenabled="false" numberofrunspersimulation="0"

numberofsimulations="0"/> <geographicoutputdetail description="COUNTY"/> <outputemissionsbreakdownselection> <modelyear selected="false"/> <fueltype selected="true"/> <emissionprocess selected="false"/>

<onroadoffroad selected="true"/> <roadtype selected="true"/> <sourceusetype selected="false"/> <movesvehicletype selected="false"/>

<onroadscc selected="false"/>

<offroadscc selected="false"/> <estimateuncertainty selected="false" numberOfIterations="2" keepSampledData="false" keepIterations="false"/>

<sector selected="false"/> <engtechid selected="false"/> <hpclass selected="false"/> </outputemissionsbreakdownselection> <outputdatabase servername="" databasename="2008SantaCruzOP42911" description=""/> <outputtimestep value="Year"/> <outputvmtdata value="false"/> <outputsho value="false"/> <outputsh value="false"/> <outputshp value="false"/> <outputshidling value="false"/> <outputstarts value="false"/> <outputpopulation value="false"/> <scaleinputdatabase servername="" databasename="c04023y2008_in20110329" description=""/> <pmsize value="0"/>

### 23 <outputfactors>

<timefactors selected="true" units="Years"/>

<distancefactors selected="true" units="Miles"/> <massfactors selected="true" units="U.S. Ton" energyunits="Million BTU"/> </outputfactors>

<savedata>

</savedata>

<donotexecute>

</donotexecute>

<generatordatabase shouldsave="false" servername="" databasename="" description=""/> <donotperformfinalaggregation selected="false"/> <lookuptableflags scenarioid="" truncateoutput="true" truncateactivity="true"/> </runspec>

### 24



## Appendix 2: MOVES 20 11 Ou tput F ile and Run Specification

Output File: Definitions and Values

Category

Field Value Description

State ID 4 ARIZONA

County ID 4023 Santa Cruz County

Fuel Type ID 1 Gasoline

Fuel Type ID 2 Diesel Fuel

Road Type ID 1 Off

- Network

Road Type ID 2 Rural Restricted Access

Road Type ID 3 Rural Unrestricted Access

Road Type ID 4 Urban Restricted Access

Road Type ID 5 Urban Unrestricted Access



### Output File: PM-10 Total and Break Out by Fuel and Roadway Type (units in pounds)

Fuel Road Run Total

PM10 Brake

PM10 Elemental

Carbon

PM10 Organic

Carbon

PM10 Sulfate

PM10 Tire

PM10

1 1 1 1983 0 661 1321 0 0

1 2 1 1926 283 238 1688 0 734

1 3 1 1396 2104 172 1224 0 1191

1 4 1 941 930 119 822 0 485

1 5 1 2819 10137 359 2461 0 2764

2 1 1 1392 0 369 1022 0 0

2 2 1 15638 428 13642 1996 0 561

2 3 1 6394 665 4889 1505 0 274

2 4 1 3632 528 2794 838 0 142

2 5 1 12960 3149 9258 3702 0 492

Totals 49081 18224 32501 16579 0 6643

### 25

Output File: Energy and Distance by Fuel and Roadway Type (units in MMBtu and miles)

Fuel Road Run Total Energy Distance

1 1 1 83,885

1 2 1 463,338 89,093,696

1 3 1 508,149 100,401,000

1 4 1 228,870 42,884,000

1 5 1 1,088,672 178,216,000

2 1 1 30,836

2 2 1 481,052 21,702,200

2 3 1 157,447 8,825,700

2 4 1 91,302 4,341,050

2 5 1 269,850 12,053,900

Totals 3,403,401 457,517,546



### MOVES 2011 Run Specification

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### 26

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</offroadvehiclesccs> <roadtypes> <roadtype roadtypeid="1" roadtypename="Off-Network"/> <roadtype roadtypeid="2" roadtypename="Rural Restricted Access"/>

### 27

<roadtype roadtypeid="3" roadtypename="Rural Unrestricted Access"/> <roadtype roadtypeid="4" roadtypename="Urban Restricted Access"/> <roadtype roadtypeid="5" roadtypename="Urban Unrestricted Access"/> </roadtypes> <pollutantprocessassociations> <pollutantprocessassociation pollutantkey="100" pollutantname="Primary Exhaust PM10 - Total" processkey="1" processname="Running Exhaust"/> <pollutantprocessassociation pollutantkey="100" pollutantname="Primary Exhaust PM10 - Total" processkey="2" processname="Start Exhaust"/> <pollutantprocessassociation pollutantkey="100" pollutantname="Primary Exhaust PM10 - Total" processkey="15" processname="Crankcase Running Exhaust"/> <pollutantprocessassociation pollutantkey="100" pollutantname="Primary Exhaust PM10 - Total" processkey="16" processname="Crankcase Start Exhaust"/> <pollutantprocessassociation pollutantkey="100" pollutantname="Primary Exhaust PM10 - Total" processkey="17" processname="Crankcase Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="100" pollutantname="Primary Exhaust PM10 - Total" processkey="90" processname="Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="110" pollutantname="Primary Exhaust PM2.5 - Total" processkey="1" processname="Running Exhaust"/> <pollutantprocessassociation pollutantkey="110" pollutantname="Primary Exhaust PM2.5 - Total" processkey="2" processname="Start Exhaust"/> <pollutantprocessassociation pollutantkey="110" pollutantname="Primary Exhaust PM2.5 - Total" processkey="15" processname="Crankcase Running Exhaust"/> <pollutantprocessassociation pollutantkey="110" pollutantname="Primary Exhaust PM2.5 - Total" processkey="16" processname="Crankcase Start Exhaust"/> <pollutantprocessassociation pollutantkey="110" pollutantname="Primary Exhaust PM2.5 - Total" processkey="17" processname="Crankcase Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="110" pollutantname="Primary Exhaust PM2.5 - Total" processkey="90" processname="Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="106" pollutantname="Primary PM10 - Brakewear Particulate" processkey="9" processname="Brakewear"/> <pollutantprocessassociation pollutantkey="102" pollutantname="Primary PM10 - Elemental Carbon" processkey="1" processname="Running Exhaust"/> <pollutantprocessassociation pollutantkey="102" pollutantname="Primary PM10 - Elemental Carbon" processkey="2" processname="Start Exhaust"/> <pollutantprocessassociation pollutantkey="102" pollutantname="Primary PM10 - Elemental Carbon" processkey="15" processname="Crankcase Running Exhaust"/> <pollutantprocessassociation pollutantkey="102" pollutantname="Primary PM10 - Elemental Carbon" processkey="16" processname="Crankcase Start Exhaust"/> <pollutantprocessassociation pollutantkey="102" pollutantname="Primary PM10 - Elemental Carbon" processkey="17" processname="Crankcase Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="102" pollutantname="Primary PM10 - Elemental Carbon" processkey="90" processname="Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="101" pollutantname="Primary PM10 - Organic Carbon" processkey="1" processname="Running Exhaust"/> <pollutantprocessassociation pollutantkey="101" pollutantname="Primary PM10 - Organic Carbon" processkey="2" processname="Start Exhaust"/> <pollutantprocessassociation pollutantkey="101" pollutantname="Primary PM10 - Organic Carbon" processkey="15" processname="Crankcase Running Exhaust"/> <pollutantprocessassociation pollutantkey="101" pollutantname="Primary PM10 - Organic Carbon" processkey="16" processname="Crankcase Start Exhaust"/> <pollutantprocessassociation pollutantkey="101" pollutantname="Primary PM10 - Organic Carbon" processkey="17" processname="Crankcase Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="101" pollutantname="Primary PM10 - Organic Carbon" processkey="90" processname="Extended Idle Exhaust"/>

### 28

<pollutantprocessassociation pollutantkey="105" pollutantname="Primary PM10 - Sulfate Particulate" processkey="1" processname="Running Exhaust"/> <pollutantprocessassociation pollutantkey="105" pollutantname="Primary PM10 - Sulfate Particulate" processkey="2" processname="Start Exhaust"/> <pollutantprocessassociation pollutantkey="105" pollutantname="Primary PM10 - Sulfate Particulate" processkey="15" processname="Crankcase Running Exhaust"/> <pollutantprocessassociation pollutantkey="105" pollutantname="Primary PM10 - Sulfate Particulate" processkey="16" processname="Crankcase Start Exhaust"/> <pollutantprocessassociation pollutantkey="105" pollutantname="Primary PM10 - Sulfate Particulate" processkey="17" processname="Crankcase Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="105" pollutantname="Primary PM10 - Sulfate Particulate" processkey="90" processname="Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="107" pollutantname="Primary PM10 - Tirewear Particulate" processkey="10" processname="Tirewear"/> <pollutantprocessassociation pollutantkey="116" pollutantname="Primary PM2.5 - Brakewear Particulate" processkey="9" processname="Brakewear"/> <pollutantprocessassociation pollutantkey="112" pollutantname="Primary PM2.5 - Elemental Carbon" processkey="1" processname="Running Exhaust"/> <pollutantprocessassociation pollutantkey="112" pollutantname="Primary PM2.5 - Elemental Carbon" processkey="2" processname="Start Exhaust"/> <pollutantprocessassociation pollutantkey="112" pollutantname="Primary PM2.5 - Elemental Carbon" processkey="15" processname="Crankcase Running Exhaust"/> <pollutantprocessassociation pollutantkey="112" pollutantname="Primary PM2.5 - Elemental Carbon" processkey="16" processname="Crankcase Start Exhaust"/> <pollutantprocessassociation pollutantkey="112" pollutantname="Primary PM2.5 - Elemental Carbon" processkey="17" processname="Crankcase Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="112" pollutantname="Primary PM2.5 - Elemental Carbon" processkey="90" processname="Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="111" pollutantname="Primary PM2.5 - Organic Carbon" processkey="1" processname="Running Exhaust"/> <pollutantprocessassociation pollutantkey="111" pollutantname="Primary PM2.5 - Organic Carbon" processkey="2" processname="Start Exhaust"/> <pollutantprocessassociation pollutantkey="111" pollutantname="Primary PM2.5 - Organic Carbon" processkey="15" processname="Crankcase Running Exhaust"/> <pollutantprocessassociation pollutantkey="111" pollutantname="Primary PM2.5 - Organic Carbon" processkey="16" processname="Crankcase Start Exhaust"/> <pollutantprocessassociation pollutantkey="111" pollutantname="Primary PM2.5 - Organic Carbon" processkey="17" processname="Crankcase Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="111" pollutantname="Primary PM2.5 - Organic Carbon" processkey="90" processname="Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="115" pollutantname="Primary PM2.5 - Sulfate Particulate" processkey="1" processname="Running Exhaust"/> <pollutantprocessassociation pollutantkey="115" pollutantname="Primary PM2.5 - Sulfate Particulate" processkey="2" processname="Start Exhaust"/> <pollutantprocessassociation pollutantkey="115" pollutantname="Primary PM2.5 - Sulfate Particulate" processkey="15" processname="Crankcase Running Exhaust"/> <pollutantprocessassociation pollutantkey="115" pollutantname="Primary PM2.5 - Sulfate Particulate" processkey="16" processname="Crankcase Start Exhaust"/> <pollutantprocessassociation pollutantkey="115" pollutantname="Primary PM2.5 - Sulfate Particulate" processkey="17" processname="Crankcase Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="115" pollutantname="Primary PM2.5 - Sulfate Particulate" processkey="90" processname="Extended Idle Exhaust"/> <pollutantprocessassociation pollutantkey="117" pollutantname="Primary PM2.5 - Tirewear Particulate" processkey="10" processname="Tirewear"/> <pollutantprocessassociation pollutantkey="91" pollutantname="Total Energy Consumption" processkey="1" processname="Running Exhaust"/>

### 29

<pollutantprocessassociation pollutantkey="91" pollutantname="Total Energy Consumption" processkey="2" processname="Start Exhaust"/> <pollutantprocessassociation pollutantkey="91" pollutantname="Total Energy Consumption" processkey="90" processname="Extended Idle Exhaust"/> </pollutantprocessassociations>

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### 30

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### 1 

# 2008 and 2011 PM10

Emissions Inventories

Nogales Municipality State of Sonora, Mexico

U.S. Environmental Protection Agency Region 9

Draft Final, April 24, 2012This page is intentionally blank.

### 2 

## Contents

1. Introduction................................................................................................................ ............3

2. The Nogales Municipality, Sonora, Me xico and the Nogales NAA, Arizona.......................4

3. Source Data Summary ...........................................................................................................6

4. Emissions Inventory Methodology........................................................................................8

4.1 Overview of Source Categor y Emission Estimate Development.......................8

4.2 Point Sources Estimate ..............................................................................................8

4.3 Area Sources Estimates.......................................................................9

4.4 Mobile Sources Estimate .........................................................................................15

4.5 Nonroad Sources Estimate..................................................................16

5. Emissions Inventory Results and Discussion ......................................................................17

References......................................................................................................20

### 3 

## 1. Introduction

1.1 Purpose

This document provides an estimated PM10 emission inventory for all PM10 sources within the Nogales Municipality, State of S onora, Mexico and the details con cerning the derivation of those

emissions estimates. EPA has created this PM 10 emissions inventory to support the Arizona Department of Environmental Quality’s (ADEQ) work on a PM10 State Implementation Plan (SIP) for the Nogales PM10 Non-attainment Area (NAA) , located in Santa Cruz County, Arizona. Specifically, an estimate of PM10 emissions is needed to dete rmine if the Nogales NAA would

have attained the PM10 National Ambient Air Quality Standard (NAAQS) but for emissions emanating from sources in the Nogales Municipality.

1.2 Sources of PM10

PM10 refers to particulate matter of ten microns or less in aerodynamic diameter. Another class of particles, denoted as PM2.5 also called fine particulate, refers to pa rticles of 2.5 microns or less in aerodynamic diameter. PM10 includes both PM2.5 and the particulates with aerodynamic diameter

between 2.5 and 10 microns. Sometimes referred to as PM2.5-10, this larg er fraction is called “coarse” particulate. While fine particles originate mostly from combustion sources and secondary aerosol generation processes, coar se particles usually originate from mechanical activities and fugitive source categories. Typical major sources of PM10 include fugitive dust, open burning including wild fires, mineral crus hing and grinding operations, agri cultural activities such as land tilling, dust suspended from vehicle travel on paved and unpaved roads and, to a lesser extent, fuel

combustion sources and mobile source exhaust.

1.3 Emissions Inventory Overview

The emissions data for this inventory came from two primary sources and was estimated in part using data or methods from these and other cited sources:

1. “Mexico National Emissions Inventory, 1999: Si x Northern States”, Final, April 30, 2004, prepared by Eastern Research Group (ERG), Acosta Y Asoc iados, and Transengineering,

for the Secretariat of the Environment and Na tural Resources and the National Institute of Ecology of Mexico, the United States Envi ronmental Protection Agency, the Western Governors’Association, and the North American Commission for Environmental Cooperation. (1999 Mexico NEI)

2. “Development of Mexico National Emissi ons Inventory Projections for 2008, 2012, and 2030”, Final, January 9, 2009, prepared by East ern Research Group, Inc. (ERG) for the Instituto Nacional de Ecologia, Mexico C ity, Mexico, the National Renewable Energy Laboratory, and the United States Environmen tal Protection Agency, with assistance from

the Western Governors’ Associat ion. (2008-12 NEI Projections) These sources were supplemented by emissions es timates using data from emissions inventories from other areas in the United States (U.S.) /Mexico border area and by calculated emissions estimates using EPA AP-42 emissions fact ors for unpaved and paved road emissions. 1 

### We describe

1 See sections 4.3.2.1 and 4.3.2.2 for AP-42 emission factor equations and discussion of inputs.

### 4 in detail within Sections 3 and 4 the methodology used to compile emissions source category estimates. Mexico population data used in this emissions inventory was taken from census data at

the Instituto Nacional de Estadistic a Geografia e Informatica, (INEGI), www.inegi.mx.org . We used population data from 1995, 2000, 2005, and 2010.



## 2. The Nogales Municipality, Sonora, Mexico and the Nogales NAA, Arizona

2.1 Geography of the Area

The combined communities of Nogales, Arizona and Nogales, Sonora, or Ambos Nogales are

located within the Sonoran Dese rt. This desert covers 120,000 square miles with a minimum elevation of 2,500 feet and is in the Basin and Range topographic province. This topography is characterized by north-south elongated valleys surr ounded by mountain ranges. Ambos Nogales is

located in such a north-south vall ey created by the Nogales Wash running north to the Santa Cruz

River.

From south to north, Nogales Municipality is ro ughly analogous to a U.S. county and covers a 632.5 square mile area along the U.S./Mexico border. 2 

### The largest urban cent er in the municipality is the City of Nogales, Sonora. Nogales, Sonora, Mexico lies directly so uth of Nogales, Arizona across the international border. Collectively referred to as Ambos Nogales, the communities of Nogales, Arizona and Nogales, Sonora, Mexico comprise the larges t international border community in Arizona, with a combin ed population of 232,550 inhabitants in 2010. 3 

### The majority of the Nogales Municipality population live within the city of Nogales, Sonora. The mean elevation in Nogales, Sonora is 4,265 feet above sea level. 4 

### At 5,380 feet, the highest elevation area in Nogales, Sonora are in th e Cerro de los Nogales (Nogales Hill), west of where the Obregón and Colosio routes meet, near th e southern end of the city.

The Alvaro Obregón Boulevard, Luis Donaldo Colo sio Boulevard, and the Corredor Fiscal toll road are the main transportation routes in Nogales, Sonora. The Alvaro Obregón Boulevard runs the length of the narrow Nogales Wash valley, an d is a highly congested route used by local and

some cross-border commercial traffic. The Corre dor Fiscal is a toll road for cross-border commercial traffic; its on- and off-ramp access is limited to the border junction at Mariposa Road and a point just outside of the southern city limits of Nogales, Sonora. The Corredor Fiscal conducts the majority of the U.S. and Me xico cross-border commercial traffic.

Proceeding northward, the U.S./Mexico border fo rm the southern boundary of the Nogales NAA and Santa Cruz County, Arizona. Near the cente r of the Nogales NAA, the city of Nogales, Arizona is sixty miles south of Tucson, Arizona in the middle and southernmost portion of Santa Cruz County. The city of Nogales, Arizona is the largest city in the 76.1 square mile nonattainment

area. 5 

### The mean elevation in Nogales, Arizona is 3,865 feet. Mountain ranges near Nogales include the Patagonia Mountains to the east a nd the Tumacacori, Atascosa, and Pajarito

2 Municipality land area was calculated by EPA using GIS software.

3 Nogales, Arizona had 20,017 inhabitants and Nogales, Sonora, Mexico had 212,533 inhabitants. U.S. Census

Bureau 2010 and Instituto Nacional de Estadi stica Geografia e Informatica, (INEGI) 2010.

4 “Statistical Municipal Workbook for Nogales, Sonora,” 2005 edition, INEGI.

5 Nogales NAA land area was calculated by EPA using GIS software.

### 5 Figure 1: Nogales Municipality and Ambos Nogales Urban Areas.

### 6 mountains to the west. Approxima tely twenty-five miles to the nor th are the Santa Rita Mountains and Madera Canyon in the Coronado National Forest where Mount Wrightson ri ses to an elevation of 9,432 feet. Northwest of Interstate 19 are the Cerro Colorado, Las Guijas, and Sierrita Mountain Ranges.

Major highways in the Nogales, Arizona area ar e Arizona State Route 82, which connects Nogales, Arizona with Patagonia, Arizona (19 miles) and Sonoita (31 mile s) to the northeast, and U.S. Interstate 19 which connects Tucson, Arizona to Nogales, Arizona and continues south into México, where it becomes Federal Highway 15.



## 3. Source Data Summary

3.1 The 1999 Mexico National Emissions Inventory

The Nogales Municipality emissions inventory developed here is based on modifications to the 1999 Mexico NEI estimate for the Nogales Municipality and allocations from the 2008-12 NEI Projections. For the Nogales Municipality, the 1999 Mexico NEI provided PM10 emissions

estimates in four broad source ca tegories: point, area, mobile, and non-road mobile; see Table 1 below. More individual source category detail wa s added at the State of Sonora and national scale of analysis; for example, detailed point and ar ea source information was provided for the State of Sonora. For later use and comparison, the State of Sonora emissions estimates are provided below in Table 2. We have provided the PM2.5 estim ates here for informational and comparison purposes only.

Table 1: Nogales Municipality PM10 and PM2.5 Emissions Inventory for 1999 (Mega-grams, Mg).

Source Category PM10 PM2.5

Point 0.8 0.0

Area 7,815.8 1,407.2

Mobile 22.5 18.4

Nonroad 3.8 3.5

Total 7,842.9 1,429.1 Source: "1999 Mexico National Emissions Inventory: Six Northern States" Final, April 2004



### Table 2: State of Sonora, Mexico Emissions PM10 and PM2.5 Inventory for 1999 (Mg).

Source Category PM10 PM2.5

Point 30,880.6 14,737.2

Area 96,766.4 22,225.9

Mobile 236.2 193.5

Nonroad 1,157.9 1,065.3

Total 129,041.1 38,221.9 Source: "1999 Mexico National Emissions Inventory: Six Northern States," Final, April 2004

### 7 3.2 1999 Mexico National Emissions Inventory and 2008 and 2012 Projections

The 2008-12 NEI Projections provided national le vel emission estimates for the years 2008 and 2012, as well as aggregate detailed information on the source categories. The document also estimated 2030 emissions, but those were not releva nt to this analysis. See Table 3 below.

Table 3: Mexico PM10 Emissions Inventory for 1999, 2008, and 2012 (Mg).

Source Category 1999 2008 2012

Point 297,264 359,919 388,825

Area 439,253 483,735 443,800

Mobile 20,567 31,890 34,019

Nonroad 37,240 40,447 42,734 Source: “Development of Mexico National Emissions Inventory Projections for 2008, 2012, and 2030”



### 3.3 Population

This section presents the population estimates fo r Mexico, the State of Sonora, and the Nogales Municipality. We used Mexico population data from the national census at the Instituto Nacional de Estadistica Geografia e Informatica, (INEGI) website, www.inegi.mx.org . Using population data from the 1995, 2000, 2005, and 2010 Mexico census, we interpolated popul ation estimates for 1999, 2008, 2011, and 2012; these estimates are provi ded below in Table 1. The 1999 population estimates were interpolated using 1995 and 2000 census data. The 2008 population estimates were interpolated using 2005 and 2010 census data. The 2011 and 2012 population estimates were forecasted from the 2010 census data assuming the same increment of annual increment growth for the period 2005 to 2010.

Table 4: Population Data for Selected Years: 1995 to 2012.

Population Data for 1995, 2000, 2005, and 2010 with Interpolated or Projected Values for 1999, 2008, 2011, and 2012

1995 1999 2000 2005 2008 2010 2011 2012

Mexico 91,158,290 96,218,388 97,483,412 103,263,388 108,707,278 112,336,538 114,151,168 115,965,798

State of Sonora 2,085,536 2,190,682 2,216,969 2,394,861 2,555,432 2,662,480 2,716,004 2,769,528

Nogales Municipality 133,49 1 154,528 159,787 193,517 209, 582 220,292 225,647 231,002 Source for 1995, 2000, 2005, and 2010 census data: INEGI



### 3.3.1 Population Based Allocation Ratios

Where applicable, we allocated 2008 and 2012 nationa l emissions projections based on the Nogales Municipality’s share of national population growth. The exceptions were the Nogales Municipality point source estimate and the area source estimates for paved and unpaved road emissions, agricultural burning, and ag ricultural tilling emissions . These exceptions are discussed in Section

4.

The population-based allocation values for scalin g a municipality share of national emissions growth were as follows: (1) for the period 1999-2008, 4.41 x 10 -3 

### ; and, (2) for the period 2008-2012, 2.95 x 10 -3



### .

### 8 These ratios were calculated using the following formula: Ratio 1999-2008 = (Nogales2008 - Nogales 1999) / (Mexico2008 – Mexico1999); Ratio 2008-2012 = (Nogales2012 – Nogales 2008) / (Mexico2012 – Mexico2008); where NogalesXXXX and MexicoXXXX are INEGI popul ation estimates for the respective year.



## 4. Emissions Inventory Methodology

4.1 Overview of Source Category Emissions Estimates Development

The 1999 Mexico NEI provided PM10 emissions estimates for all f our major source categories, point, area, mobile, and non-road at three levels of analysis: national, state, and municipality; and, it provided more detailed area source category emi ssions estimates at the national and state levels of analysis. The 2008-2012 NEI Projections provided national estimates in detail, but did not provide disaggregated data at the state or muni cipality level of analys is and did not provide estimates for unpaved and paved road emissions.

To summarize, we estimated emissions as follows:

 for point sources we used a combined scali ng methodology to provide an estimated range;

 for area sources, we scaled most source cate gories by population; we calculated directly unpaved and paved road emissions; and, we s caled agricultural em issions by land area;

 for mobile and nonroad sources , we scaled by population.

Each section below describes in detail how we es timated municipality emissions for each of the major source categories using source document in formation and other cited source data.

4.2 Point Sources Estimate

The 1999 Mexico NEI estimated point source emissions for the Nogales Munici pality at 0.8 Mg of PM10. The 1999 Mexico NEI and the 2008-12 Projections did not specify eith er the sources that composed this estimate, or their respective locati ons at the municipality level. The 1999 Mexico NEI provided specific point source da ta at the State of Sonora level, but no location information. For Sonora, the 1999 Mexico NEI showed 30,888.6 Mg of PM10 from 51 point sources: 97 percent of these emissions came from 11 mines, seven utilities, and three primary metal manufacturing facilities. 6 

### The remaining three percent of emissions came from 30 other sources, manufacturing facilities. This suggests that in 1999 it was unlikel y that a large mining, utility, metal manufacturing source was located in the Noga les Municipality given the very low reported total municipality point source emissions (0.8 Mg), compared to the average individual source emissions in these three largest source cat egories, mining, utiliti es, and primary metal manufacturing (1,426.8 Mg).

Lacking existing source type or location data, we estimated a ra nge of point source projections using two scaling calculations: (1) scaling the same rate of national grow th to the municipality level; and, (2) scaling the relative national emissions increment by population ratios in Section 3.3.1.

6 Page B-5, "1999 Mexico National Emissions Inventory: Six Northern States," Final, April 2004.

### 9 For example, for the period 1999 to 2008 national point source emissions grew 21.1 percent, so 0.8 Mg was multiplied by 1,211 to get 0.97 Mg. To apply a population growth ratio for the 1999-2008 period, we calculated the national point sour ce emissions growth increment, 62,655 Mg and multiplied it by 0.00441, and added that municipal shar e of national point source emissions growth to 0.8 Mg. to get 277 Mg in 2008.

Table 5: Nogales Municipality 1999, 2008, and 2012 PM10 Emissions: Point Sources (Mg).

Scaling Method 1999 2008 2012

National Emissions Growth 0.8 0.97 1.04
Population Ratio 0.8 277 362.3



### 4.3 Area Sources Estimates

The 1999 Mexico NEI estimated area source emissi ons for the Nogales Muni cipality at 7815.8 Mg. Unfortunately, the 1999 Mexico NEI and the 2008-12 Projections did not speci fy the sources that composed this estimate at the municipality le vel. The 1999 Mexico NE I provided specific area

source data at the State of Sonora level of analysis and we reviewed that information to see which sources composed this estimate; see Table 6 below.

Table 6: State of Sonora Area Source Category Emissions by Source, 1999 (Mg).

Area Source PM10 Share
Unpaved Road Dust 61,049.3 63.1%

Paved Road Dust 26,516.5 27.4%
Agricultural Burning 4,120.0 4.3%

Agricultural Tilling 1,959.3 2.0%

Residential Fuel Combustion-Wood 1,529.3 1.6%
Open Burning - Waste 582.7 0.6%

Construction Activities 222.2 0.2%

All others/Remainder 787.1 0.8%

Total 96,766.4 Source: "1999 Mexico National Emissions Inventory: Six Northern States," Final, April 2004



### Three observations suggested our approach for es timating area source emissions for the Nogales Municipality. First, the Nogale s Municipality area source estima te was an even larger proportion (99.7 percent) of total emissions compared to th e same State of Sonora pr oportion (75 percent); see Tables 1 and 2 for area source estimates. Second, the 1999 Nogales Municipality distribution of area source types would not differ markedly and would be a subset of the known State of Sonora distribution of area source categorie s. Third, the largest proportion of area source emissions in either the State of Sonora or Nogales Municipa lity was in two source categories, unpaved and paved road dust. We, therefore, decided to do the following: (1) estimate directly unpaved and paved road emissions for the Nogales Municipality; (2) disaggregate to the municipality level the remaining State of Sonora area source categories in Table 6 and adjust them, where possible, by local information; and, (3) allocate the 2008 and 2012 national emissions pr ojections for our selected area source categories based on the Nogales Municipality’s share of na tional population growth, except for agricultural emissions which were allocated by a land area scaling. Table 7 shows the national estimated emissions for the source catego ries analogous to those in Table 6.

### 10 Table 7: Selected Mexico Area S ource Category Emissions: 1999, 2008, 2012 (Mg).

Source Category 1999 2008 2012
Agricultural Burning 13,975 14,059 14,059

Agricultural Tilling 109,866 119,206 119,206

Residential Fuel Combustion-Wood 226,897 238,550 199,340
Open Burning - Waste 20,425 22,432 23,122

Construction Activities 9,448 10,664 11,093

Remainder of Area Sources 58,642 78,824 76,980 Source: “Development of Mexico National Emissions Inventory Projections for 2008, 2012, and 2030”



### 4.3.1 Disaggregated 1999 Area Source Baseline Estimates for Nogales Municipality

Before proceeding with calcula ting unpaved and paved road em issions and estimating 2008 and 2012 emissions for the remaining area source categor ies, we developed the disaggregated 1999 area source baseline estimates for the Nogales Municipality.

To provide a 1999 baseline emissions estimate for use in calculating 2008 and 2012 emissions estimates for the agricultural bur ning and tilling source categories, we proportionally scaled the Sonora emissions for these source categories by th e 2010 Nogales Municipality proportion (195) of Sonora (565,297) total harvested hectares 7 

### , 0.000345, to get the following results:

 agricultural bur ning, 1.42 Mg;

 agricultural til ling, 0.676 Mg. To the degree that the total harvested hectares in Nogales Municipality have grown from 1999 to 2010 relative to the Sonora total, then using a 2010 based ratio to estimate 1999 emissions may introduce some double-counting of th ese source category emissions.

To provide a Nogales Municipality 1999 baseli ne emissions estimate for the residential wood combustion, open burning of waste, constructi on activities, and the remaining area source categories, we proportionally scaled the State of Sonora emissions fo r these source categories by the 1999 Nogales Municipality proportion of the State of Sonora population, 0.071, to get the following results:

 residential wood combustion, 107.87 Mg;

 open burning of waste, 41.1 Mg;

 construction activities, 15.67 Mg; and,

 remaining area source categories, 55.52 Mg.

For comparison purposes, we calculated the Noga les Municipality 1999 unpaved and paved road emissions at 4,923.6 Mg and 2,648.1 Mg, respectively, us ing the same emission factor input data as the 1999 Mexico NEI and updated 2006 and 2011 EP A AP-42 emission factor equations for unpaved and paved road dust.

7 Information was taken from the INEGI website: www.inegi.org.mx.

### 11 Finally, as a check against our area source category disaggregation calculations we compared the total of our disaggregated 1999 area source emissi ons estimate with the total area source estimate reported in the 1999 Mexico NEI:

 estimated 1999 area source baseline total, 7,793.97 Mg;

 1999 Mexico NEI estimate, 7,815.8 Mg.

The difference between the two emissions es timates is 21.9 Mg., or 0.28 percent.

4.3.2 Unpaved and Paved R oad Estimates Overview

Unpaved and paved road emissions estimates begin with an equation of the form:

PM10 emissions = [(Total VKT) (VKT percent pa ved or unpaved)] x EFpaved or unpaved,

where VKT is vehicle kilometers traveled and EF is the calculated emissions factor (grams/kilometer). A primary input to both unpav ed and paved emissions estimates are VKT and the percentage of kilometers miles tr aveled on unpaved versus paved roads.

For the Nogales Municipality, we could not locate publically available VKT estimates derived from transportation demand modeling. Co nsequently, as was done in th e 1999 Mexico NEI, we used a 4.3 VKT per person per day rate multiplied by populat ion to get a daily VKT estimate. In the 1999 Mexico NEI, the 4.3 VKT per person per day rate was used to estimate VKT for cities ranging in size from 100,000-250,000 population, and repr esented the “large town rate”. 8



### For the Nogales Municipality, the 1999 Mexico NE I used an unpaved/paved road VKT split of 8/92 percent estimated for the “large town” population category of 100,000-250,000. 9 

### We could not locate subsequent publicly availa ble estimates of for unpaved/pave d road mileage splits for the Nogales Municipality. Beginning in 2005, the City of Nogales, Sonora instituted a program to pave unpaved roads using funds provided to the Muni cipality by the North American Development

Bank. 10 

### The “2005 Mexicali Emissions Inventory” (2005 Mexicali EI) provided the following unpaved/paved road VKT splits: urban road miles, 2/98; suburban road miles, 6.1/93.9; and rural road miles, 10.3/89.7. 11 

### To provide a consistent and cons ervative estimate of unpaved and paved road emissions, we used the 6/94 unpaved/paved percentage VKT as a midpoint value from the

Mexicali information and to account for an in crease in paved roads within the Nogales Municipality since 1999. For comparison, the 1999 Mexico NEI used a 3/97 VKT split for the next higher “small city” size category. Our estimated range of emissions for unpaved and paved roads

8 pages 5-3 to 5-5 and Appendix A, “1999 Mexico NEI: Six Northern States,” April 2004 Final. To summarize, per capita per day VKT estimates were developed using transportation engineering gravity modeling of seven representative urban areas varying by population size.

9 “Estimation of Paved and Unpaved Road Dust in Mexico”, presentation by Marty Wolf, Paula Fields, and Salvador Gonzalez-Ayala, at NARSTO Emissions Inventory Conference, October 14-17, 2003. Unpaved and paved road area and VKT splits were calculated for seven representative urban areas using GIS, field mapping, satellite images, or aerial photographs.

10 The North American Development Bank provided $17million to pave 300,000 square meters of urban streets in residential areas. www.nadb.org.

11 Table 10, page B-19, “2005 Mexicali Emissions Inventory”, Final Report, February 27, 2009, Eastern Research Group, Inc. (ERG).

### 12 will be generated by the difference between the input data for the respective emission factor calculations; the input data and those di fferences are discussed below.

A third common input factor to each unpaved and unpa ved emissions factor calculation is the mean number of precipitation days w ith greater than 0.1 inch of precipitation. For the Nogales Municipality estimate, we used 55 precipitation days, as reported by the National Weather Service for Nogales, Arizona.

4.3.2.1 Unpaved Road Estimate

To calculate unpaved road emissions, we us ed the EPA AP-42, Chapter 13.2.2, November 2006, Final, emissions factor equation:

EF (lb/VMT) = [(k((s/12)^1) ((S/30)^0.5) / (M/0.5)^0.2) -C] x [(365 - p)/365]

where k = 1.8 pound of PM10/Vehicl e Mile Traveled (VMT), a constant supplied with the equation; s = silt content percen tage; S = vehicle speed; M = moistu re content; C = a constant for brake, tire wear, and exhaust emissions 0.00047; a nd p = precipitation days. Once we calculated an emissions factor in pounds/VMT, this was convert ed to grams/VKT for use with the metric units of measurement in our source documents; the conversion factor is 1 pound/VMT equals 281.9 gram/VKT.

Regarding vehicle speeds (S), we used 20.3 miles per hour (mph) as in the 1999 Mexico NEI. We did not find publically available ro ad link vehicle speed estimates fo r the Nogales Municipality. As a check, we consulted the 2005 Mexicali EI and f ound that this study used the following: 11 mph, urban roads; 18 mph, suburban roads; and, 25 mph, rural roads.

For moisture content (M), we used 0.26 percent, as in the 1999 Mexico NEI. We did not find any publically available unpaved road silt moisture content studies for Nogales Municipality. To compare, the average silt moisture percentage used for the Mexicali and San Luis Rio Colorado Emission Inventories was 0.12 and 0.18, respectively. Also, Yuma, Arizona, near San Luis Rio Colorado, Mexico has 17 precipitation days as compared to the 55 in Nogales, Arizona, suggesting the use of a higher silt moisture percentage.

Because we held other emission factor input vari ables constant, silt content estimates produce the greatest variability in our unpaved road emissions factor. See Tabl e 8 for a list of observed values

we collected.

### 13 Table 8: Silt Content Percentages in U.S./M exico Border Area PM10 Emissions Estimates.

Study or Source Silt Content (%) Variation Reported

1999 Mexico NEI 7.54 ---
2005 Mexicali EI (avg) 12 2.93 0.24 Minimum and 8.21 Maximum
WASBAQS: San Luis Rio Colorado (avg) 13 0.76 0.34 Minimum and 1.85 Maximum
Nogales Planning Area (ADEQ) 7.05 ---
Douglas /Paul Spur Planning Area (avg)(ADEQ) 4.7 Range reported, 1.3 to 7.0
Pima/Yuma/Pinal (avg) (ADEQ) 7.6 Range reported, 4.3-11.0



### For our estimate range, we used 2.93 and 7.54 percent as minimum and maximum estimates for silt content percentage as they repr esent observed values in Mexico Border cities, Mexicali and Ciudad Juarez, respectively. For comp arison. the average low of all studies was 3.46 percent and the average high of all studies was 7.11 percent; wher e no high or low was reported we used the point estimate in both averages. The ADEQ reported values were used in past air quality planning estimates for these areas, but we were unable to confirm the source data. Our calculation results

are shown below:

 using the variables described above and a 2.93 pe rcent silt content per centage, we calculate a 0.34956 lb/Vehicle Mile Traveled, or a 98.540 grams/VKT emissions factor; and,

 using the variables described above and a 7.54 pe rcent silt content per centage, we calculate a 0.90017 lb/Vehicle Mile Traveled, or a 253.76 grams/VKT emissions factor.

Table 9: Nogales Municipality 1999, 2008, and 2011 PM10 Emissions: Unpaved Roads (Mg).

Silt Content Percentage 1999 2008 2011

Low Estimate: 2.93% --- 1,944.8 2,093.9
High Estimate: 7.54% 4,923.6 5,008.3 5,392.2

Note: the 1999 estimate used a 8/92 percent, unpaved/paved road VKT split per 1999 Mexico NEI.



### 4.3.2.2 Paved Road Estimate

To calculate paved road emissions, we used the EPA AP-42, Chapter 13.2.1, January 2011, Final, emissions factor equation:

EF (lb/VMT) = [(k(sL)^0.91) x (W^1.025)] x [1- (p/4N)]

where k = 0.0022 pound of PM10/Vehicle Mile Traveled (VMT), a particle size multiplier constant supplied with the equation; sL = si lt loading in grams/square meter; W = vehicle weig ht (average); p = precipitation days; and N = days in period of in terest, in this case 365 or one year. As stated above we used 55 for precipitation days. Once we calculated an emissions factor in pounds/VMT, this was converted to grams/VKT for use with the metric units of m easurement in our source documents; the conversion factor is 1 pound/VMT equals 281.9 gram/VKT.

For vehicle weight (W), we used an average 2.4 t ons per vehicle as used in the 1999 Mexico NEI.

12 Raw data values supplied by Marty Wolf, Eastern Research Group, Inc.

13 Raw data values supplied by Marty Wolf, Eastern Research Group, Inc. WASBAQS refers to the Western Arizona Sonora Border Air Quality Study.

### 14 Because we held other emission factor input vari ables constant, silt loading observations produce the greatest variability in our unpaved road emi ssions factor. See Table 10 below for a list of

observed values we collected.

Table 10: Silt Loading in U.S./Mexico Border Area PM10 Emissions Estimates.

Study or Source Silt Loading (gr/m2) Variation Reported

1999 Mexico NEI 9.97 ---
2005 Mexicali EI (avg) 14 0.3106 0.0011 Minimum and 1.329 Maximum

WASBAQS: San Luis Rio Colorado (avg) 15 0.22285 0.0857 Minimum and 0.6524

Maximum
Nogales, AZ Planning Area (ADEQ) 0.8 ---



### For our estimate range, we used 0.0857 and 1.329 grams per square meter (gr/m2) as minimum and maximum estimates for silt loading as they repr esent observed values in Mexico border cities, Mexicali and San Luis Rio Colorado, respectively. For comparison, the aver age low of all studies was 0.02956 gr/m2 and the average high of all stud ies was 0.92713 gr/m2; the 0.8 gr/m2 cited for Nogales, Arizona was incorporated in both averag es. We did not incorporate the 9.97 value in these averages because it is so disparate from th e other values; also, we could not obtain a copy of the Ciudad Juarez study so as to better understa nd the 9.97 gr/m2 figure to explain the large

difference between it and other obs erved values. ADEQ provided valu es for Nogales, Arizona used in past air quality planning estimates for the area , but we are unable to co nfirm the source data and whether or not it derives from samples collected in Nogales, Arizona; co nsequently, we used a value of known derivation, 1.329 gr/m2. The resu lts of our calculations are shown below:

 using the variables described above and a 0.0857 gr/m2 silt loading, we calculate a 0.00055523 lb/Vehicle Mile Traveled, or a 0.15 6520 grams/VKT emissions factor; and,

 using the variables described above and a 1.329 gr/m2 silt loading, we calculate a 0.06728 lb/Vehicle Mile Traveled, or a 1.897 grams/VKT emissions factor.

Table 11: Nogales Municipality 1999, 2008, a nd 2011 PM10 Emissions: Paved Roads (Mg).

Silt Loading 1999 2008 2011
Low Estimate: 0.0857 gr/m2 --- 48.4 52.1
High Estimate: 1.329 gr/m2 2,648.1 586.4 631.4

Note: the 1999 estimate used a 8/92 percent, unpaved/paved ro ad VKT split and 9.97 gr/m2 silt loading per the 1999 Mexico NEI.



### 4.3.3 Agricultural Burning and Tilling Estimates

The Nogales Municipality 1999 baseline em issions estimates are as follows:

 agricultural tilling, 0.676 Mg; and,

 agricultural burni ng, 1.42 Mg.

From 1990 to 2009, Mexico’s harvested surface area increased 4.8 percent and cultivated surface area increased 11.5 percent 16 

### ; or, 0.24 to 0.57 percent per year, re spectively. It is unknown if a significant portion of this national increase in ag ricultural activity o ccurred on land within the Municipality, but rather than hold the 1999 emissions estimates c onstant, we increased them by

14 Raw data supplied by Marty Wolf, Eastern Research Group, Inc.

15 Raw data supplied by Marty Wolf, Eastern Research Group, Inc.

16 “Mexico at at glance: 2010” INEGI.

### 15 these annual percentages through 2008. There are no projected emissions increases in 2012. The percentage increase in cultivation was applied to tilling, while the percentage increase in harvesting was applied to burning.

Table 12: Nogales Municipality 1999, 2008, and 2012 PM10 Emissions: Agricultural Tilling and Burning (Mg).

1999 2008 2012
Agricultural Tilling 0.676 0.69 0.69
Agricultural Burning 1.42 1.49 1.49



### 4.3.4 Residential Wood Burning, Open Bu rning, and Construction Estimates

The Nogales Municipality 1999 baseline em issions estimates are as follows:

 residential wood burning, 107.87 Mg;

 open burning of waste, 41.1 Mg; and,

 construction activities, 15.67 Mg.

For these source categories, we allocated 2008 and 2012 national emission s projections based on the Nogales Municipality’s share of nationa l population growth. Residential wood burning

emissions estimates decrease from 2008 to 2012 due to use of cleaner burning fuels; projections show fuel swapping to and increased use of natura l gas. Construction activity emissions estimates may be overstated depending on the local impact of decreased activity within the housing and commercial construction markets in Nogales Municipality.

Table 13: Nogales Municipality 1999, 2008, and 2012 PM10 Emissions: Residential Wood Combustion, Open Burning of Waste, and Construction Activities (Mg).

1999 2008 2012
Residential Wood Burning 107.87 159.24 43.53
Open Burning of Waste 41.1 49.95 51.99

Construction Activities 15.67 21.03 22.3



### 4.3.5 The Remaining Area Sources Estimate

The Nogales Municipality 1999 baseline em issions estimate is as follows:

 remaining area source categories, 55.52 Mg.

For this aggregation representing the twenty-f our other area source ca tegories within the 1999 Mexico NEI, we allocated 2008 and 2012 national emissions projections based on the Nogales Municipality’s share of national population growth. The 2012 decrease can be attributed again to

decreases in other residential fuel combustion source categories as fu el swapping to cleaner fuels is projected to occur (e.g., from coal to natural gas).

Table 14: Nogales Municipality 1999, 2008, a nd 2012 PM10 Emissions: Remaining Area Sources (Mg).

1999 2008 2012
Remaining Area Sources 55.52 144.49 139.05

### 16 4.4 Mobile Sources Estimate

The Nogales Municipality 1999 baseline em issions estimate is as follows:

 mobile sources, 22.5 Mg. For this source category, we allocated 2008 and 2012 national emissions projections based on the Nogales Municipality’s share of national population growth.

The mobile source emissions estimate includes ve hicle exhaust, tire wear, and brake wear emissions. In producing the mobile source emissions projections from 1999, the 2008-12 projections took into account the following parameters:

 changes in vehicle technologies a nd emissions due to fleet turnover;

 new Mexican gasoline and diesel vehicle fuel standards; and,

 implementation of Mexican emissions standards.

The mobile source emissions estimates were generated with a MOBILE6-Mexico emissions

model. 17 

### Motor vehicle fuel demand projections pr ovided the basis for estimating growth in vehicle usage in future year emissions. 18 

### As discussed earlier, we i ndependently estimated VKT to calculate unpaved and paved road emissions. While there appears to be a difference in methodology concerning projected on-road motor vehicle usage, there is no overlap in the emissions sources being estimated, direct vehicle emissions versus reintrained road dust.

Table 15: Nogales Municipality 1999, 2008, and 2012 PM10 Emissions: Mobile Sources (Mg).

1999 2008 2012

Mobile Sources 22.50 72.41 78.7



### 4.5 Nonroad Sources Estimate

The Nogales Municipality 1999 baseline emissions estimate is as follows:

 nonroad sources, 3.8 Mg.

For this source category, we allocated 2008 and 2012 national emissions projections based on the Nogales Municipality’s share of national population growth.

The 1999 NEI emissions estimate addressed dies el powered agricultu ral and construction equipment, only. The 2008-12 Projections used disa ggregated fuel demand projections to estimate emissions for the transportati on, industrial, commercial, and agricultural sectors.

Table 16: Nogales Municipality 1999, 2008, and 2012 PM10 Emissions: Non-road Sources (Mg).

1999 2008 2012

Nonroad Sources 3.80 17.94 24.69

17 For a more detailed discussion of mobile source emissions modeling see the source document: “Development of Mexico National Emissions Inventory Projections for 2008, 2012, and 2030”, Final, January 9, 2009, prepared by Eastern Research Group, Inc. (ERG).

18 To estimate growth in on-road motor vehicle emissions over the 1999 to 2030 timeframe, the 2008-12 NEI Projections document relied on the “Long-range Energy Alternatives Planning System” (LEAP) to project gasoline and other vehicle fuel demand and use. For more information on the LEAP and its use, see 2008-12 NEI projections document and D. Cuatecontzi (2008) “Long-range Energy Alternatives Planning System (LEAP) fuel projections”, National Autonomous University of Mexico, August 6.

### 17 

## 5. Emissions Inventory Results and Discussion

The Nogales Municipality emissions inventory results are shown below in Tables 17 and 18. Table 17 aggregates the emissions estimates from S ection 4. Table 18 provides 2008 and 2011 estimated

PM10 emissions in tons.

Table 17: PM10 Emissions Inventory for Nogales Municipality, 1999, 2008, 2011, 2012 (Mg).

Source Category Range 1999 2008 2011 2012

Point Sources Low Estimate 0.8 0.97 1.02 1.04
High Estimate

--- 277 353.71 362.3

Area Sources Unpaved Road Low Estimate

--- 1,944.8 2,093.9
High Estimate 4,923.6 5,008.3 5,392.2

Paved Road Low Estimate

--- 48.4 52.1
High Estimate 2,648.1 586.4 631.4
Agricultural Tilling 0.676 0.69 0.69
Agricultural Burning 1.42 1.49 1.49

Residential Wood Combustion 107.87 159.24 42.50 43.53
Open Burning of Waste 41.1 49.95 50.76 51.99

Construction Activities 15.67 21.03 21.77 22.3
Remaining Area Sources 55.52 144.49 135.75 139.05

Mobile Sources 22.5 72.41 76.83 78.7

Nonroad Sources 3.8 17.94 24.10 24.69

Total Low Estimate

--- 2461.41 2500.92

Total High Estimate 7,821.06 6,338.94 6,731.22 Note: The 1999 unpaved and paved road estimates were recalculated using current AP-42 emission factors equations and data inputs from the 1999 Mexico NEI; consequently, we did not generate 1999 high and low estimates. Please see section 4.3.2 and subsections for a complete discussion of unpaved and paved estimates.



### Table 18: PM10 Emissions Inventory for Nogales Municipality for 2008 and 2011 (Tons).

Source Category Range 2008 2011

Point Sources Low Estimate 1.07 1.12
High Estimate 305.34 389.90

Area Sources Unpaved Road Low Estimate 2,143.77 2,308.13
High Estimate 5,520.70 5,943.88

Paved Road Low Estimate 53.35 57.43
High Estimate 646.39 696.00
Agricultural Tilling 0.76 0.76
Agricultural Burning 1.64 1.64

Residential Wood Combustion 175.53 46.85
Open Burning of Waste 55.06 55.95

Construction Activities 23.18 24.00
Remaining Area Sources 159.27 149.64

Mobile Sources 79.82 84.69

Nonroad Sources 19.78 26.57

Total Low Estimate 2,713.24 2,756.79

Total High Estimate 6,987.48 7,419.89

Conversion factor: 1 Megagram = 1.10231 U.S. short tons (one short ton = 2000 pounds)

### 18 Because we started with 2012 national level project ed estimates for most source categories, we scaled estimates to the municipal level first, then adjusted the municipal es timates consistent with the estimated decrease from 2012 to 2011 municipa lity population estimates, 2.37 percent. We calculated directly 2011 emission estimates for unpaved and paved roads; no adjustment was needed. Agricultural tilling and burning emissions estimates for 2011 reflected 2012 projections,

no increase from 2008. We disc uss specific issues concerning the allocated and estimated emissions inventory below.

5.1 Lack of Point Source Location Data

Neither source document, the 1999 Mexico NEI or the 2008-12 Projections, provided municipalityspecific point source information, such as source category and location. C onsequently, it is not possible to validate the 2008 or 2012 pr ojections with specific source information or activity levels. This may not introduce a large range of uncerta inty, however, because the beginning baseline emissions estimate, 0.8 Mg, is so small in comparison to the total emissions i nventory. Even with a two orders of magnitude increase to 80 Mg, the point source emissions estimate remains very small ( 3.25 percent) compared to the 2008 total i nventory low estimate of 2,461.41 Mg.

5.2. Use of Nogales Municipality Specific Data

Particularly for estimating unpaved and paved road emissions, Nogales Municipality specific data was not publically available. For instance, in calculating the 2008 and 2011 unpaved and paved road emission estimates, we used surrogate estim ators for vehicle kilometers traveled and the unpaved/paved road split inputs. While we used reasonable and valid su rrogates, having Nogales Municipality specific input information and acti vity levels would make these estimates less qualified. For other inputs to the unpaved and paved road emissions factor calculations, such as silt content and silt loading, any Nogales Municipality poi nt estimate would result from of a range of samples from differently classifi ed urban, suburban, rural areas or road way types. So, calculating a single emissions estimate from a range of silt content and silt loading inputs is not unusual, by itself. Also, where possible we used recent data collected from Mexican cities on the Mexico and

U.S. border.

Consolidating and projecting the “remaining area s ources” category is likely to introduce an overestimate in that some of the sources may not ex ist in Nogales Municipality, or it may not be appropriate to scale all such sources by a population-based allocation. Again, only Nogales Municipality specific area source information would have adjudicated this issue.

The 1999 NEI did not estimate border crossing em issions and the 2008-12 projections did not estimate PM10 emissions at border crossings. C onsequently, while aggregate emissions were accounted for in the source documents, the incremental and local PM10 emissions effects at the border crossing was not factored into this analysis.

Finally, the 2008 and 2012 estimated rate of PM10 em issions from road and other construction may be high because it is unclear whet her the national emissions estimate reflected the full magnitude of the downturn in the local economy’s real estate sector.

### 19 5.3 Estimated Range of Emissions

To allow for a lack of specific information for the point source category and a range of silt content and silt loading input variables in the unpaved and paved road categ ories, we generated a range of emissions estimates to get high and low estimates. As we explained for the silt content and silt loading values, any Nogales Munici pality single emissions estimate would result from of a range of samples from differently classifi ed urban, suburban, rural areas or road way types. So, calculating a single emissions estimate from a range of silt content and silt loading inputs is not unusual. The difference that might be anticipat ed would be that stratified sa mpling of different roadway areas and roadway types would contain th e variability about the specific sa mple mean for each strata. Thus, depending on the sampling strategy and its execution, stratified sampling may provide for less variability around specifi c strata or overall mean point estimates.

5.4 Overall Assessment

This emissions inventory for Nogales Municipal ity provides a complete and sufficiently accurate inventory for the area based on the best methodol ogy and source data publically available at the time the inventory was developed. Where Nogales Municipality specific data does not exist or could not be located, and we could not justify a singular data input, we reported a range of emissions estimates. In allocating national emissions to the Nogales Municipa lity or in estimating emissions, EPA has used reasonable and conser vative assumptions to produce a current, comprehensive, and reasonably accurate PM10 emissi ons inventory. This emissions inventory is adequate for its intended use, providing an aggreg ate estimate of PM10 emissions originating from areas south of the Nogales, Ar izona PM10 nonattainment area.

### 20 

## References

“Mexico National Emissions Inventory, 1999: Si x Northern States”, Final, April 30, 2004, prepared by Eastern Research Gr oup (ERG), Acosta Y Asociados, and Transengineering, for the

Secretariat of the Environment and Natural Res ources and the National In stitute of Ecology of Mexico, the United States Envir onmental Protection Agency, the We stern Governors’Association,

and the North American Commission for Envi ronmental Cooperation. (1999 Mexico NEI).

“Development of Mexico National Emissions Inventory Projections for 2008, 2012, and 2030”, Final, January 9, 2009, prepared by Eastern Resear ch Group, Inc. (ERG) for the Instituto Nacional de Ecologia, Mexico City, Mexico, the Nationa l Renewable Energy Laboratory, and the United States Environmental Protection Agency, with assistance from the Western Governors’ Association. (2008-12 NEI Projections).

“Technical Support Document for Recommendation th at the Nogales, Arizona Area Be Designated as a PM2.5 Nonattainment Area”, Arizona Depart ment of Environmental Quality, December 3,

2007.

“Estimation of Paved and Unpaved Road Dust in Mexico”, presentation by Marty Wolf, Paula Fields, and Salvador Gonzalez-Ayala, at NARST O Emissions Inventory Conference, October 14-
17, 2003.

“2005 Mexicali Emissions Inventory”, Final Repo rt, February 27, 2009, Eastern Research Group, Inc. (ERG).This page is intentionally blank.

# Analysis of Ambient PM 10 

# Levels, Topography, and

Meteorological Data in Nogales, Arizona: 2007 - 2009

U.S. Environmental Protection Agency

Region 9

Draft Final: July 20, 2012

### 2



## Table of Contents

1.0 Introduction

1.1 Purpose

1.2 Sources of PM 10 

### 1.3 Geography of the Ambos Nogales Area

2.0 Ambient PM 10 

### Monitoring in Nogales, Arizona and Nogales, Sonora

2.1 Ambient Monitors

2.2 Selected Timeframe for Review 2.3 Quality Assurance

3.0 Analysis of 2007 - 2009 Exceedance Days

3.1 Hourly PM 10 

### Concentration, Wind Speed, and Wind Direction 3.2 Representative Day 3.3 Pattern and Timing of Exceedances 3.4 Study Days 3.5 Local Topography and Landscape 3.6 Analyses of Wind Direction and PM 10 

### Concentration

3.7 Estimated 24-Hour Average Concentrations for Nogales NAA Under Meteorological Conditions Contributing to International Transport

4.0 Discussion

4.1 Disparity in Observed Ambient Values 4.2 Long Range Transport 4.3 Local Sources Near Nogales, Arizona Monitor

4.4 Observations of Coarse Versus Fine Particulate Matter 4.5 Review of 2010 and 2011 Exceedance Days

5.0 Conclusions

List of Tables

Table 1: Twenty four hour PM 10 

### concentrations on exceedance days in 2007. Table 2: Twenty four hour PM 10 

### concentrations on exceedance days in 2008. Table 3: Twenty four hour PM 10 

### concentrations on exceedance days in 2009. Table 4: Hourly PM 10 

### concentration, wind speed, and wind direction at the Nogales, Arizona Post Office FEM monitor versus time for November 16, 2008. Table 5: Percentage of observed PM 10 

### concentrations attributable to wind direction. January 1, 2007, May 22, 2008, and January 1, 2009 are excluded from the analysis of exceedance days (see Section 3.4 for discussion of “Study Days.”).

### 3

Table 6: Ambient PM 10 

### concentrations sorted by concentration value and wind direction, 2007 - 2009 exceedance days

Ta ble 7: Average PM 10 

### concentration for hours associated with wind direction from the south (135 - 224 degrees) versus all other directions for all exceedance days.

Ta ble 8: 2008 PM 10 

### Emission Inventories: Nogales NAA, Arizona and Nogales Municipality, Mexico (low estimate) (tons per year)

Table 9: 2008 PM 10 

### Emission Inventories: Nogales NAA, Arizona and Nogales Municipality, Mexico (high estimate) (tons per year) Table 10: Estimated 24-hour Average PM 10 

### Concentrations (μg/m 3 

### ) for 29 Exceedance Days Weighted According to Decision Rules for Mexican Influence Table 11: Six Exceedance Days Where Observations Exist for Nogales AZ Monito rs and Nogales, Sonora Monitor: 24-hour concentrations (μg/m 3 

### ).

Ta ble 12: Six Exceedance Days Where Observations Exist for Nogales AZ Monitor and Noga les, Sonora Monitor: Concentration Values Disaggregated by Southerly Wind Quadrant versus All Other Wind Directions (μg/m 3 

### ). Table 13: Twenty-four Hour PM 10 

### and PM 2.5 

### concentrations ( g/m 3 

### ), and the ratio of

observed PM 10 

### :PM 2.5 

### on exceedance days at the Nogales, Arizona Post Office monitoring site (2007 - 2009).

Ta ble 14: Average PM 10 

### concentration for hours associated with wind direction from the south (135 - 224 degrees) versus all other directions for 2010 exceedance days.

L ist of Figures

Figure 1: Map of Ambos Nogales area and Nogales PM-10 Nonattainment Area. Figure 2: Map of ambient PM 10 

### monitors near Nogales, Arizona. Figure 3: PM 10 

### exceedances at the Nogales, Arizona Post Office, by month and year. Figure 4: Hourly PM 10 

### concentration at the Nogales, Arizona Post Office FEM monitor versus time of day for all 29 exceedances. Figure 5: Hourly PM 10 

### concentration at the Nogales, Arizona Post Office FEM monitor versus time of day for all exceedances, excluding three study days (26 days, see Section 3.4 discussion of study days). Figure 6: Hourly wind speed at the Nogales, Arizona Post Office FEM monitor versus time of day for all 29 exceedances. Figure 7: Hourly temperature at the Nogales, Arizona Post Office FEM monitor versus time of day for all 29 exceedances. Figure 8: Wind rose of wind speed versus wind direction at the Nogales, Arizona Post Office FEM monitor for all days (2007 - 2009).

F igure 9: Wind rose of wind speed versus wind direction at the Nogales, Arizona Post Office FEM monitor for all 29 exceedance days. Figure 10: Wind rose of wind speed versus wind direction at the Nogales, Arizona Post Office FEM monitor for all exceedances, excluding May 22, 2008 (see text). Figure 11: Pollution rose of PM 10 

### concentration versus wind direction at the Nogales, Arizona Post Office FEM monitor for all 29 exceedance days. Figure 12: Pollution rose of PM 10 

### concentration versus wind direction at the Nogales, Arizona Post Office FEM monitor for all exceedances, excluding study days (26 days).

### 4

Figure 13: Hourly PM 10 

### concentration and wind speed at the Nogales, Arizona Post Office FEM monitor versus time for November 16, 2008. Figure 14: Hourly PM 10 

### concentration, wind speed, and temperature at the Nogales, Arizona Post Office FEM monitor versus time for all exceedances, excluding January 1, 2007, Ma y 22, 2008, and January 1, 2009 (see section 3.4). Figure 15: Hourly PM 10 

### concentration and wind speed at the Nogales, Arizona Post Office FEM monitor versus time for May 22, 2008. Figure 16: Hourly PM 10 

### concentration and wind speed at the Nogales, Arizona Post Office FEM monitor versus time for (a) January 1, 2007 and (b) January 1, 2009. Figure 17: Elevated Topographical View of Ambos Nogales Area from Northwest

Pe rspective With Nogales, Sonora Highlighted and International Border in Red Line. Figure 18: Long Aerial and Elevation Transect of Nogales Arizona (shaded in yellow) and Nogales, Sonora (shaded in pink). Figure 19: Short Aerial and Elevation Transect of Nogales, Arizona (shaded in yellow) and Nogales, Sonora (shaded in pink). Figure 20: Hourly PM 10 

### concentrations at the Nogales, Arizona Post Office FEM monitor versus time of day for all exceedances between January 1, 2010 and September 30, 2011 compared to average PM 10 

### concentrations from Figure 14 (2007 - 2009).

F igure 21: Hourly wind speed at the Nogales, Arizona Post Office FEM monitor versus time of day for all exceedances in 2010 compared to average wind speed from Figure 14 (2007 - 2009).

### 5



## 1.0 Introduction

1.1 Purpose

This document provides an analysis of ambient PM 10 

### concentrations and meteorological data within the Nogales Nonattainment Area (NAA). The Arizona Department of Environmental Quality (ADEQ) requested that EPA provide this analysis to support

AD EQ’s work on a PM 10 

### State Implementation Plan (SIP) for the Nogales NAA, located

in S anta Cruz County, Arizona. The primary purpose of this analysis is to determine how the area’s meteorology and topography have an effect on exceedances of PM 10 

### National Ambient Air Quality Standard (NAAQS) and whether or not there is a south to north directional component to these exceedances; particularly, in reference to the international border between Nogales, Arizona and Nogales, Sonora, Mexico.

1.2 S ources of PM 10



### PM 10 

### refers to particulate matter with an aerodynamic diameter less than or equal to 10

micrometers. PM 2.5 

### , also called fine particulate, refers to particulate matter with an aerodynamic diameter less than or equal to 2.5 micrometers. PM 10 

### includes both PM 2.5 

### and the particulates with aerodynamic diameter between 2.5 and 10 micrometers, which

is referred to as PM 10 -2.5 

### . This larger fraction is called “coarse” particulate. While fine

pa rticles originate mostly from combustion sources and secondary aerosol generation processes, coarse particles usually originate from mechanical activities and fugitive source categories. Typical sources of PM 10 

### include fugitive dust, open burning including wild fires, mineral crushing and grinding operations, agricultural activities such as land tilling, dust suspended from vehicle travel on paved and unpaved roads and, to a lesser extent, fuel combustion sources and mobile source exhaust.

1.3 Geography of the Ambos Nogales Area

The combined communities of Nogales, Arizona and Nogales, Sonora, or Ambos Nogales are located within the Sonoran Desert . This desert covers 120,000 square miles

with a minimum elevation of 2,500 feet and is in the Basin and Range topographic province. This topography is characterized by north-south elongated valleys surrounded

b y mountain ranges. Ambos Nogales is located in such a north-south valley created by

the N ogales Wash running north to the Santa Cruz River.

From south to north, Nogales Municipality is roughly analogous to a United States (U.S.) county and covers a 632.5 square mile area along the U.S./Mexico border. 1 

### The largest urban center in the municipality is the City of Nogales, Sonora. Nogales, Sonora, Mexico lies directly south of Nogales, Arizona across the international border. Collectively referred to as Ambos Nogales, the communities of Nogales, Arizona and Nogales,

S onora, Mexico comprise the largest international border community in Arizona, with a

1 Nogales Municipality land area was calculated by EPA using GIS software.

### 6

combined population of 232,550 inhabitants in 2010. 2 

### The majority of the population within the Nogales Municipality lives within the city of Nogales, Sonora. The mean

e levation in Nogales, Sonora is 4,265 feet above sea level. 3 

### At 5,380 feet, the highest elevation area in Nogales, Sonora are in the Cerro de los Nogales (Nogales Hill), west of

whe re the Obregón and Colosio routes meet, near the southern end of the city.

The Alvaro Obregón Boulevard, Luis Donaldo Colosio Boulevard, and the Corredor Fiscal toll road are the main transportation routes in Nogales, Sonora. The Alvaro

Obr egón Boulevard runs the length of the narrow Nogales Wash valley, and is a highly

c ongested route used by local and some cross-border commercial traffic. The Corredor

F iscal is a toll road for cross-border commercial traffic; its on- and off-ramp access is

li mited to the border junction at Mariposa Road and a point just outside of the southern city limits of Nogales, Sonora. Th e Corredor Fiscal conducts the majority of the U.S. and

Mex ico cross-border commercial traffic.

Proceeding northward, the U.S. and Mexico border form the southern boundary of the Nogales NAA and Santa Cruz County, Arizona. At the lower center of the Nogales NAA, the city of Nogales, Arizona is sixty miles south of Tucson, Arizona in the middle

a nd southernmost portion of Santa Cruz County. The city of Nogales, Arizona is the

lar gest city in the 76.1 square mile nonattainment area. 4 

### 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 w est. Approximately twenty-five miles 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 Colorado, Las Guijas, and Sierrita Mountain Ranges.

Major highways in the Nogales, Arizona area are Arizona State Route 82, which connects Nogales, Arizona with Patagonia, Arizona (19 miles) and Sonoita (31 miles) to the

northe ast, and U.S. Interstate 19 which connects Tucson, Arizona to Nogales, Arizona

a nd continues south into México, where it becomes Federal Highway 15.

2 Nogales, Arizona had 20,017 inhabitants and Nogales, Sonora, Mexico had 212,533 inhabitants. U.S. Census Bureau 2010 and Instituto Nacional de Estadistica Geografia e Informatica, (INEGI) 2010.

3 “Statistical Municipal Workbook for Nogales, Sonora,” 2005 edition, INEGI.

4 Nogales NAA land area was calculated by EPA using GIS software.

### 7

Figure 1: Map of Ambos Nogales area and Nogales PM-10 Nonattainment Area.

### 8



## 2.0 Ambient PM 10 

## Monitoring in Nogales , A rizona and Nogales, Sonora

2.1 Ambient Monitors

Five ambient air monitors in the vicinity of Ambos Nogales were considered for this analysis. These monitors are described below and see Figure 2 for their locations. Within the nonattainment area, the Nogales, Arizona Post Office is the primary violating

monitor location for PM 10



### . The Nogales, Arizona Post Office monitoring site is 0.3 miles north of the border and this monitoring site is 0.9 miles northeast of the Nogales, Sonora Fire Station monitoring site. The Green Valley and Corona de Tucson monitoring sites are approximately 35 and 45 miles away from the U.S./Mexico border, respectively.

Also, Arizona has operated a meteorological data collection station at the Nogales, Arizona Post Office monitoring site; wind speed observations discussed in our analyses were collected at that location. Temperature observations were collected at the Nogales International Airport, approximately six miles northeast of the Nogales, Arizona Post Office monitoring site.

Nogales, Arizona Post Office, Met One BAM 1020 (Method Code: 122) PM 10 

### SPMFEM (AQS ID: 04-023-0004, POC 3). The majority of the 24-hour PM 10 

### exceedance s measured in the Ambos Nogales area occurred at this monitor. This monitor operates

c ontinuously. Although this monitor is designated as a Special Purpose Monitor ( SPM ) monitor, the data that it produces is appropriate to consider for regulatory purposes since it has been operational for more than 24 months and has a Federal Equivalency Method ( FEM) designation.

Nogale s, Arizona Post Office, Rupprecht and Patashnick Partisol 2000 (Method Code: 126) PM 10 

### SLAMS-FRM (AQS ID: 04-023-0004, POC 1). Th is monitor is placed at the same station as the primary violating monitor. Unlike the continuous FEM monitor operating at the Nogales, Arizona Post Office, this monitor is filter-based with samples collected once every six days (1:6) and is designated as a Federal Reference Method ( FRM) monitor. For most of the days that the continuous FEM monitor is violating, the filter-based FRM monitor does not have sample information.

Nogales, Sonora Fire Station, Sierra Anderson Lo-Volume Dichot (Method Code: 073) PM 10 

### Non-Regulatory-FRM (AQS ID: 80-026-0005, POC 1). The Nogales, Sonora Fire Station is the closest monitoring site to the Nogales , Arizona Post Office site.

The PM 10 

### monitor operating at this site is also a filter-based monitor with once in every six day sampling, but is designated as a non-regulatory FEM. This is the only PM 10 

### monitor in Nogales, Sonora or the nearby vicinity south of the international border.

Green Valley, Arizona, Multiple Methods, Met One BAM 1020 (Method Code: 122)

an d Rupprecht and Patashnick TEOM (Method Code: 079) PM 10 

### SPM-FEM (AQS ID: 04-019-1030, POC 1). This is the closest monitor to the Nogales, Arizona Post

Of fice on the U.S. side with the same scale of representation (neighborhood scale) as the

P ost Office violating monitor. This monitor operates continuously and is a SPM-FEM.

### 9

Corona de Tucson, Arizona, Rupprecht and Patashnick Partisol 2000 (Method

Code: 126) PM 10 

### SLAMS-FRM Background (AQS ID: 04-019-0008, POC 1): This monitor represents the nearest background site to the Ambos Nogales area. This monitoring site is designated as a State and Local Air Monitoring Station (SLAMS) and

the PM 10 

### monitor is also an FRM with filter-based samples once every six days.

Figure 2: Map of ambient PM 10 

### monitors near Nogales, Arizona.

### 10

2.2 Selected Timeframe for Review

The twenty-four hour PM 10 

### NAAQS is based on the number of expected exceedances greater than 150 g/m 3 

### averaged over three years 5 

### . For this analysis, we considered the

most recent and most complete three year data range available. There was a large period

of missing data at the Nogales, Arizona Post Office PM 10 

### SPM between March 16 and October 27, 2010 because of poor quality assurance and quality control results. Consequently, we considered 2007 to 2009 to be the most appropriate timeframe for this analysis

. At the Nogales, Arizona Post Office monitors, PM 10 

### data completeness for each quarter within the 2007

- 2009 timeframe is greater than 75 percent.

2. 3 Quality Assurance

The Corona de Tucson and the Green Valley monitors located near Tucson, Arizona are operated by the Pima County Department of Environmental Quality (PDEQ), while the Nogales Post Office and the Sonora Fire Station monitors are operated by ADEQ. PDEQ and ADEQ have an appropriate quality system in place for collecting ambient air monitoring data. EPA performed an independent Technical System Audit (TSA) of ADEQ’s ambient air monitoring program in September 2009 and a TSA of PDEQ’s ambient monitoring program in September 2011, per requirements in 40 CFR Part 58, Appendix A, Section 2.5. EPA assessed PDEQ and ADEQ’s compliance with

e stablished regulations governing the collection, analysis, validation, and reporting of ambient air quality data and concluded that PDEQ and ADEQ have a robust ambient air

moni toring program.

EPA reviewed and approved the 2011 ADEQ annual monitoring network plan on December 1, 2011. We found that the 2011 monitoring network plan was complete and met the requirements for annual network plans described in 40 CFR 58.10.



## 3.0 Analysis of 2007 - 2009 Exceedance Days

The measured twenty-four hour average PM 10 

### concentrations on exceedance days during 2007 - 2009 for the Nogales, Arizona Post Office FEM, FRM (filter-based monitor at the

sa me location), Nogales, Sonora Fire Station (closest monitor), Green Valley, (closest monitor in U.S.), and Corona de Tucson, (background monitor), are listed below in

Tables 1-3. 6

5 The NAAQS for all pollutants can be found at www.epa.gov/air/criteria.html .

6 Data was obtained via EPA’s Air Quality System (AQS), www.epa.gov/ttn/airs/airsaqs/

.

### 11

Table 1: 24-hour PM 10 

### concentrations on exceedance days in 2007.

Date (2007) Nogales, AZ

Post Office FEM ( g/m 3 ) Nogales, AZ

Post Office FRM ( g/m 3 ) Nogales,

Sonora Fire Station ( g/m 3 ) Green

Valley, AZ ( g/m 3 ) Cor o na de

Tucson, AZ ( g/m 3 )

1

- Jan 210 N/A N/A 11.9 N/A

6

- Feb 180 N/A N/A 11.9 N/A

6

- Mar 157 N/A N/A 24.2 N/A

15

- Mar 175 N/A N/A 22.2 N/A

19

- Oct 189 N/A N/A 29.5 N/A

27

- Oct 210 122 159 24.9 28

2

- Nov 211 190 170 29.4 32

3

- Nov 170 N/A N/A 26.5 N/A

4

- Nov 170 N/A N/A 30.2 N/A

6

- Nov 186 N/A N/A 34.4 N/A

18

- Nov 167 N/A N/A 30.8 N/A

19

- Nov 177 N/A N/A 22.6 N/A

28

- Nov 167 N/A N/A 22.0 N/A

24

- Dec 233 N/A N/A 13.5 N/A



### Table 2: 24-hour PM 10 

### concentrations on exceedance days in 2008.

Date (200 8 ) Nogales, AZ

Post Office

FEM ( g/m 3 ) Nogales, AZ

Post Office FRM ( g/m 3 ) Nogales,

Sonora Fire

Station ( g/m 3 ) Green

Valley , AZ ( g/m 3 ) Cornoa de

Tucson , AZ ( g/m 3 )

26

- Jan 204 N/A N/A 11.8 N/A

27

- Feb 166 N/A N/A 14.6 N/A

18

- May 169 147 126 22.2 21

22

- May 217 N/A N/A 77.5 N/A

26

- Oct 156 N/A N/A 25.7 N/A

31

- Oct 159 N/A N/A 34.5 N/A

1

- Nov 234 N/A N/A 26.3 N/A

8

- Nov 167 155 119 22.5 16

16

- Nov 171 N/A N/A 33 N/A

17

- Nov 206 N/A N/A 25.4 N/A

20

- Nov 161 150 126 26.4 23

22

- Nov 179 N/A N/A 25 N/A

31

- Dec 155 N/A N/A 10.7 N/A

### 12

Table 3: 24-hour PM 10 

### concentrations on exceedance days in 2009.

Date (2009 ) Nogales, AZ

Post Office

FEM ( g/m 3 ) Nogales, AZ

Post Office FRM ( g/m 3 ) Nogales,

Sonora Fire

Station ( g/m 3 ) Green

Valley , AZ ( g/m 3 ) Cornoa de

Tucson , AZ ( g/m 3 )

1

- Jan 238 NULL 129 12.9 12

16

- Jan 204 N/A N/A 17.8 N/A



### There are no observed PM 10 

### NAAQS exceedances at the Nogales, Arizona Post Office

F RM on days when the FEM is not exceeding (i.e., days other than those shown in Tables

1 - 3).

B etween 2007 and 2009, there were 29 exceedances of the PM 10 

### NAAQS at the Nogales, Arizona Post Office monitoring location. See Figure 3. Of those exceedances, 14 occurred in 2007, 13 in 2008, and two in 2009; with 27 exceedances in the October through March annual timeframe. Twenty-four hour PM 10 

### concentrations on exceedance days varied between 155 and 238 g/m 3 

### , with some hourly measurements reaching 900 g/m 3 

### . Finally, Arizona has not flagged any of these 2007 through 2009 exceedance days for potential exclusion from air quality planning considerations under EPA’s Exceptional Events Rule.

Figure 3: PM 10 

### exceedances at the Nogales, Arizona Post Office, by month and year.

0 2 4 6 8 10 12 14

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecExceedance Day Count

2009

2008

2007

### 13

3.1 Hourly PM 10 

### Concentration, Wind Speed, and Wind Direction

Complete hourly information on PM 10 

### concentrations, wind direction, and wind speed

can be found in the file Nogales PM10 – Concentration and Met Analysis.xlsx

. Hourly information on temperature and diurnal plots of PM 10 

### concentrations and wind speed can be found in the file Nogales PM10 – Concentration and Met Analysis.xlsx

. The most relevant information for this analysis is presented and discussed here.

A plot of hourly PM 10 

### concentrations versus time of day for all exceedances is given in Figure 4. Three days were identified as having a significantly different diurnal pattern: January 1, 2007, May 22, 2008, and January 1, 2009 and are hereafter identified as “study days”. Twenty-six of the twenty-nine observed exceedances between 2007 and 2009 have nearly identical diurnal patterns and are plotted separately in Figure 5.

Figure 4: Hourly PM 10 

### concentrations at the Nogales, Arizona Post Office FEM monitor versus time of day for all 29 exceedances.

0 100 200 300 400 500 600 700 800 900 10000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00PM10(ug/m3)

Time (hour)

1/1/07 2/6/07 3/6/07 3/15/07 10/19/07 10/27/07
11/2/07 11/3/07 11/4/07 11/6/07 11/18/07 11/19/07
11/28/07 12/24/07 1/26/08 2/27/08 5/18/08 5/22/08
10/26/08 10/31/08 11/1/08 11/8/08 11/16/08 11/17/08
11/20/08 11/22/08 12/31/08 1/1/09 1/16/09

### 14

Figure 5: Hourly PM 10 

### concentrations at the Nogales, Arizona Post Office FEM monitor versus time of day for all exceedances, excluding study days (26 days, see discussion in Section 3.4).

Plots of hourly synthetic wind speed and temperature versus time of day for all exceedance days are given as Figures 6 and 7, respectively. As is shown in Figure 6, wind speeds were eight miles per hour (mph) or below for all exceedance days, with the exception of May 22, 2008, when elevated wind speeds were observed. While only one

other monitor in Arizona and a few monitors in California exceeded the 24-hour standard on May 22, 2008, on the previous day, May 21, 2008, there were eight exceedances throughout Arizona and numerous exceedances in California and Nevada associated with elevated wind speeds. 0 100 200 300 400 500 600 700 800 900 10000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00PM10(ug/m3)

Time (hour)

2/6/07 3/6/07 3/15/07 10/19/07 10/27/07 11/2/07 11/3/07

11/4/07 11/6/07 11/18/07 11/19/07 11/28/07 12/24/07 1/26/08

2/27/08 5/18/08 10/26/08 10/31/08 11/1/08 11/8/08 11/16/08

11/17/08 11/20/08 11/22/08 12/31/08 1/16/09

### 15

Figure 6: Hourly wind speed at the Nogales, Arizona Post Office FEM monitor versus time of day for all 29 exceedances.

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.00:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00Wind Speed (mph)

Time (hour)

1/1/07 2/6/07 3/6/07 3/15/07 10/19/07 10/27/07
11/2/07 11/3/07 11/4/07 11/6/07 11/18/07 11/19/07
11/28/07 12/24/07 1/26/08 2/27/08 5/18/08 5/22/08
10/26/08 10/31/08 11/1/08 11/8/08 11/16/08 11/17/08
11/20/08 11/22/08 12/31/08 1/1/09 1/16/09

### 16

Figure 7: Hourly temperature at the Nogales, Arizona Post Office FEM monitor versus time of day for all 29 exceedances.

Note: Temperatures were recorded at Nogales International Airport (NIA), 7.6 miles northeast of Nogales, Arizona Post Office monitoring site. NIA is within the Nogales PM 10 nonattainment area.



### Wind roses 7 

### are provided for non-exceedance days, all exceedance days, and exceedance days excluding May 22, 2008 in Figures 8, 9, and 10, respectively. The May 22, 2008 exceedance is excluded from Figure 9 because it is the only day with observed winds greater than 8 mph.

PM 10 

### pollution roses 8 

### for all exceedance days and exceedance days excluding the three study days identified in section 3.4 are given in Figures 11 and 12.

7 A wind rose shows the frequency of wind speed plotted in a polar coordinate system versus wind

direction.

8 A pollution rose shows the frequency of ambient concentration plotted in a polar coordinate system versus

wind direction. 25 35 45 55 65 75 85 95 105Temperature (Degrees Fahrenheit)

Time (hour)

1/1/07 2/6/07 3/6/07 3/15/07 10/19/07 10/27/07 11/2/07 11/3/07 11/4/07 11/6/07 11/18/07 11/19/07 11/28/07 12/24/07 1/26/08 2/27/08 5/18/08 5/22/08 10/26/08 10/31/08 11/1/08 11/8/08 11/16/08 11/17/08 11/20/08 11/22/08 12/31/08 1/1/09 1/16/09

### 17

Figure 8: Wind rose of wind speed versus wind direction at the Nogales, Arizona Post Office FEM monitor for non-exceedance days (2007 - 2009).

### 18

Figure 9: Wind rose of wind speed versus wind direction at the Nogales, Arizona Post Office FEM monitor for all 29 exceedance days.

### 19

Figure 10: Wind rose of wind speed versus wind direction at the Nogales, Arizona Post Office FEM monitor for all exceedances, excluding May 22, 2008 (see section 3.1).

### 20

Figure 11: Pollution rose of PM 10 

### concentration versus wind direction at the Nogales, Arizona Post Office FEM monitor for all 29 exceedance days.

2007

- 09 Nogales 29 day po llution rose Nogales 29 day pollution rose

### 21

Figure 12: Pollution rose of PM 10 

### concentration versus wind direction at the Nogales, Arizona Post Office FEM monitor for all exceedances, excluding study days (26 days).

3. 2 Representative Day

F or illustration, we identified November 16, 2008 as representative of the concentration, wind speed, and wind direction pattern observed on 26 of the exceedance days (excluding January 1, 2007; May 22, 2008; and January 1, 2009). The synthetic wind direction (SW D; in degrees, where 0 degrees is wind from the north and 180 degrees is wind from the south, etc.), synthetic wind speed (SWS; in meters per second and miles per hour), and hourly PM 10 

### concentration ( g/m 3 

### ) for November 16, 2008 is provided in Table 4

below. 2007

- 09 Nogales 2 6 day pollution rose

### 22

Table 4: Hourly observations of wind direction, wind speed, and PM 10 

### concentration at the Nogales, Arizona Post Office FEM monitor for November 16, 2008.

Hour SWD

(degrees) SWS (m/s) SWS (mph) PM 10 ( g/m 3 )

12:00:00 AM 183 0.4 0.9 222

1:00:00 AM 163 0.4 0.9 147

2:00:00 AM 180 0.5 1.1 126

3:00:00 AM 159 0.6 1.3 114

4:00:00 AM 225 0.3 0.7 64

5:00:00 AM 216 0.3 0.7 63

6:00:00 AM 168 0.5 1.1 74

7:00:00 AM 296 0.3 0.7 70

8:00:00 AM 59 0.9 2.0 43

9:00:00 AM 12 1.3 2.9 39

10:00:00 AM 14 2.1 4.7 43

11:00:00 AM 64 2.1 4.7 54

12:00:00 PM 86 2.5 5.6 22

1:00:00 PM 74 1.7 3.8 21

2:00:00 PM 77 1.2 2.7 21

3:00:00 PM 34 1.4 3.1 28

4:00:00 PM 70 1.2 2.7 25

5:00:00 PM 141 1 2.2 518

6:00:00 PM 196 0.9 2.0 226

7:00:00 PM 173 0.7 1.6 485

8:00:00 PM 154 0.4 0.9 556

9:00:00 PM 113 0.4 0.9 398

10:00:00 PM 181 0.7 1.6 463

11:00:00 PM 162 0.5 1.1 282



### A plot of hourly PM 10 

### concentrations and wind speed for the same day, November 16, 2008 is shown in Figure 13.

### 23

Figure 13: Hourly PM 10 

### concentrations and wind speed at the Nogales, Arizona Post Office FEM monitor versus time for November 16, 2008.

3. 3 Pattern and Timing of Exceedances

3.3.1 C omposite Day Using Aggregate Data

In Figure 14, a composite day is presented showing the average PM 10 

### concentration, wind speed, and temperature for each hour at the Nogales, Arizona Post Office FEM monitor across all 2007 - 2009 exceedances, excluding the previously identified study days (J anuary 1, 2007, May 22, 2008, and January 1, 2009 ). 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0

0 100 200 300 400 500 600 700 800 900 1000Wind Spped (mph)PM10 Concentration PM10 (ug/m3)

SWS (mph)

### 24

Figure 14: Average hourly PM 10 

### concentration, wind speed, and temperature at the Nogales, Arizona Post Office FEM monitor versus time of day for all exceedances, excluding January 1, 2007, May 22, 2008, and January 1, 2009 (see section 3.4 for discussion of excluded days).

3.3.2 Diurnal Pattern

For the 26 exceedance days (29 exceedances, minus three study days), there is a strong pattern of decreasing PM 10 

### concentrations in the early morning. The majority of days have a pronounced PM 10 

### increase and drop-off between 6:00 am and 9:00 am, likely indicating a reproducible direct PM 10 

### source, with the times generally corresponding to a morning commute pattern and mobile source impacts (the example day, November 16, 2008, does not show this morning increase, which may be attributable to being a Sunday, with a less pronounced morning commute). The PM 10 

### concentrations then reach their lowest points between 10:00 am and 4:00 pm, with corresponding increases in temperature and wind speed observed during those times. A pronounced spike in PM 10 

### concentration is then observed beginning between 4:00 pm and 6:00 pm, with concentrations remaining high for a couple of hours and gradually dropping off towards midnight. The afternoon spike in PM 10 

### concentrations correlates with to a significant drop in temperature, drop in wind speed, and generally a shift to variable/calm southerly (out of the south) winds. This is illustrated in Table 4, for November 16, 2008, where the spike in PM 10 

### concentration observed at 5:00 pm corresponds to a shift in wind from 70 degrees (out of the east northeast) to 141 degrees (out of the southeast) and a 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

0 50 100 150 200 250 300 350 400 450 5000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00Wind Speed(mph)PM10(ug/m3)



### Time (hour)

Concentration

Wind Speed

TemperatureTemperature(degreesFahrenheit) 80 90

70

60

50

40

30

20

10

### 25

corresponding continuous, although slight, drop in wind speed between mid-day and evening.

3.4 Study Days

3.4.1 Ma y 22, 2008

The PM 10 

### diurnal pattern for May 22, 2008 varies substantially from the other twenty-six exceedance days, with a pronounced spike in the early afternoon. PM 10 

### concentrations peak around 4:00 pm with corresponding wind speeds of 17 mph. May 22, 2008 is the only exceedance day associated with elevated winds and, as noted above, several monitors throughout the Region measured PM 10 

### exceedances on the previous day during periods of elevated winds.

Figure 15: Hourly PM 10 

### concentrations and wind speed at the Nogales, Arizona Post Office FEM monitor versus time for May 22, 2008.

3.4.2. January 1, 2007 and January 1, 2009

As noted above, the PM 10 

### diurnal pattern for January 1, 2007 and January 1, 2009, varies significantly from the other twenty-six exceedance days, with higher early morning PM 10 

### concentrations contributing more strongly to the high 24-hour average. In both cases, the diurnal pattern after mid-day looks similar to other days, with an increase in hourly PM 10 

### concentrations at 6:00 pm (although less pronounced than other exceedance days). 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0

0 100 200 300 400 500 600 700 800 900 1000Wind Speed (mph)PM10 Concentration PM10 (ug/m3)

SWS (mph)

### 26

Figure 16: Hourly PM 10 

### concentrations and wind speed at the Nogales, Arizona Post Office FEM monitor versus time for (a) January 1, 2007 and (b) January 1, 2009.

3.4.3 Consideration of December 24, 2007 and December 31, 2008

Both December 24, 2007 and December 31, 2008 are notable because they are holidays. These two days are do not have distinctly different diurnal patterns, since their diurnal

PM 10 

### concentrations closely match the patterns of other days with an afternoon increase

in PM 10 

### beginning after 4:00 pm. Both days are notable for their later spikes in PM 10 

### , however, late spikes in PM 10 

### concentration are observed on other non-holiday exceedance days, such as March 6, 2007. 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0

0 100 200 300 400 500 600 700 800 900 100012:00:00...1:00:00 AM2:00:00 AM3:00:00 AM4:00:00 AM5:00:00 AM6:00:00 AM7:00:00 AM8:00:00 AM9:00:00 AM10:00:00...11:00:00...12:00:00...1:00:00 PM2:00:00 PM3:00:00 PM4:00:00 PM5:00:00 PM6:00:00 PM7:00:00 PM8:00:00 PM9:00:00 PM10:00:00...11:00:00...Wind Speed (mph)PM10 Concentration PM10 (ug/m3)

SWS (mph)

0.0

2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0

0 100 200 300 400 500 600 700 800 900 100012:00:00 AM1:00:00 AM2:00:00 AM3:00:00 AM4:00:00 AM5:00:00 AM6:00:00 AM7:00:00 AM8:00:00 AM9:00:00 AM10:00:00 AM11:00:00 AM12:00:00 PM1:00:00 PM2:00:00 PM3:00:00 PM4:00:00 PM5:00:00 PM6:00:00 PM7:00:00 PM8:00:00 PM9:00:00 PM10:00:00 PM11:00:00 PMWind Speed (mph)PM10 Concentration PM10 (ug/m3)

SWS (mph) 

### (a)

(b)

### 27

3.5 Local Topography and Landscape

Elevations in the Ambos Nogales area are highest just south of Nogales, Sonora and decrease from south to north towards Tucson as the watershed of the Nogales Wash proceeds north to the Santa Cruz River. The mean elevation in Nogales, Sonora is 4,265

fe et. 9 

### At 5,380 feet, the highest elevation area in Nogales, Sonora is in the Cerro de los Nogales (Nogales Hill), west of where the Obregón and Colosio routes meet, near the

sout hernmost end of the city. The City of Nogales, Arizona lies 3,865 feet above sea

leve l. Nogales, Arizona rests in the Nogales Wash between the two mountain ranges, the Pajarito and Atascosa Mountains about seven miles west and the Patagonia Mountains

roug hly thirteen miles east. Figures 1 and 2 provide a general overview. Below, Figure 17 pr ovides a topographical view looking southeast towards Nogales, Sonora from an elevated viewpoint northwest of Nogales, Arizona.

Figure 17, shows the urban outline of Nogales, Sonora overlying a topographical representation of the area. The Alvaro Obregón Boulevard runs the length of the Nogales Wash valley and is depicted in the figure as the longest yellow roadway running from the top rig ht corner of the figure to the lower center of the figure at the international border (red line from running upper left to lower right) to connect with Business Interstate 19. There are four red markers in the figure: the two square red markers show the location of the Nogales, Arizona and Nogales, Sonora PM 10 

### monitor sites; and, the two small circular markers show the location of the city centers of Nogales, Arizona and Nogales, Sonora. These four markers are also shown in Figures 18 and 19.

In general, the urban area of Nogales, Sonora follows the elevation contours of the southern Nogales Wash, as opposed to a grid or square. Looking at the general topography depicted in Figure 17 (northwest perspective), there is a funnel created as the Nogales Wash falls from the higher elevations to the international border along the route of the Alvaro Obregón Boulevard and to Nogales, Arizona. Small side canyons extend

of f of the Nogales Wash bottom and into the hills surrounding hills the Nogales, Sonora city center, and to a lesser extent into Nogales, Arizona as elevations drop moving south

to north.

9 “Statistical Municipal Workbook for Nogales, Sonora,” 2005 edition, INEGI.

### 28

Figure 17: Elevated Topographical View of Ambos Nogales Area from Northwest Perspective, Nogales, Sonora Highlighted and International Border in Red Line.

To examine the local topography, within Figure 18, we ran a long south to north transect starting outside of the Nogales Wash watershed and extending northward to the Santa Cruz River (see the yellow arrow and line running right to left in Figure 18). A Nogales, Sonora subtransect is depicted by the blue arrow and line running to the vertical yellow line representing the international border. A Nogales, Arizona subtransect is depicted by the green arrow and line running from the international border to the northern edge of the Nogales NAA. The shaded area in the elevation graph below the aerial picture depicts the elevation change from the international border to the northern boundary of the Nogales NAA when following the green line in the aerial picture.

From south to north, the highest elevation of the long roadway transect is 4,331 feet at the southern edge of Nogales, Sonora, falling to the international border at 3,933 feet, continuing to the northern edge of the Nogales, Arizona PM 10 

### nonattainment area at 3,425 feet. The elevation continues to fall to approximately 3,100 feet along the Santa Cruz River watershed to the north. From the 4,331 feet high point in the transect, the elevation falls approximately 1200 feet from south to north across 34 miles.

N

### 29

Figure 18: Long Aerial and Elevation Transect of Nogales Arizona (shaded in yellow) and Nogales, Sonora (shaded in pink).

In Figure 19, a short subtransect is depicted by combining the blue and green lines in Figure 18 to form the blue line in Figure 19. Two sections of this subtransect also shows elevation declines on a south to north axis. The Nogales, Sonora section of the subtransect, shown from right to center, has an elevation drop of 201 feet over 4.8 miles to the international border (vertical yellow line), starting at the Nogales, Sonora urban boundary at 4,134 feet and dropping to 3,933 feet. The Nogales, Arizona section of the subtransect, shown from center to left, has an elevation drop of 508 feet over 10 miles from the international border to the northern boundary of the Nogales NAA (vertical red line), starting at 3,933 feet and dropping to 3,425 feet.

### 30

Figure 19: Short Aerial and Elevation Transect of Nogales, Arizona (shaded in yellow) and Nogales, Sonora (shaded in pink).

3. 6 Analys es of Wind Direction and PM 10 

### Concentration

In addition to the pollution roses in Figures 11 and 12, three analyses were performed to examine the relationship between PM 10 

### concentration and wind direction. The first analysis examined the percentage of the total observed 24-hour concentrations attributed to a given wind direction quadrant. The second analysis sorted hourly observed PM 10 

### concentrations greater than 150 g/m 3 

### into 100 g/m 3 

### bins and determined the percentage of hourly observations associated with each wind speed quadrant. The third analysis averaged the observed PM 10 

### concentration associated with winds from the south versus all other directions for each exceedance day.

In the first analysis, a weighted analysis of hourly concentration on exceedance days,

e xcluding study days, January 1, 2007; May 22, 2008; and January 1, 2009, was performed to illustrate the percent of the total observed 24-hour concentration that is attributable to winds out of specific directional quadrants: northerly (315 degrees to 44 degrees), easterly (45 degrees to 134 degrees), southerly (135 degrees to 224 degrees),

### 31

and westerly (225 degrees to 314 degrees). The analysis was performed by summing concentration data for observations corresponding to wind speeds in a given quadrant (equivalent to the sum of concentrations times time, in this case a one-hour increment) and dividing by the sum of all concentrations (again, equivalent to the sum of concentrations times one-hour increments). Interpretation of this analysis has substantial uncertainty, given the extremely low and variable wind speeds observed for the majority of high PM 10 

### concentration hours; nonetheless, the analysis illustrates broad directional correlations over the exceedance days. The complete analysis can be found in the file

N ogales PM10 – Concentration and Met Analysis.xlsx . Table 5 (below) gives the percentage of observed PM 10 

### concentrations attributable to each wind direction quadrant for all days, all exceedance days excluding the three study days, and all non-exceedance days.

Table 5: Percentage of observed PM 10 

### concentrations attributable to wind direction; January 1, 2007, May 22, 2008, and January 1, 2009 are excluded from the analysis of exceedance days (see Section 3.4 for discussion of “study days.”).

Ambient Data Sample Northerly (315

- 44°) Easterly

(45

- 134°) Southerly

(135

- 224°) Westerly

(225

- 314°)

All Days in 2007

- 2009 11% 1 6 % 63 % 10 %

Non

- Exceedance Days 11% 16% 61% 10%

Exceedance Days (minus three study

days) 7% 10 % 80 % 3%



### On all days, a large percentage (63 percent) of PM 10 

### concentration is attributable to winds out of the south, which is expected given the high frequency of winds from the south (see the windroses in Figures 8-10), regardless of any other consideration of differences in population and e missions sources by wind direction. On exceedance days, the percentage

of measured PM 10 

### concentrations increases significantly, to approximately 80 percent attributable to winds from the south. This is consistent with the analysis presented above, where high afternoon PM 10 

### concentrations on the exceedance days, excluding study days, was largely attributable to variable/slow winds out of the south. This also is

consistent with the assertion that 24-hour PM 10 

### concentrations observed on these days may not have exceeded the NAAQS if winds had not been out of the south.

In the second analysis, hourly PM 10 

### concentrations above 150 g/m 3 

### were grouped by increasingly higher 100 g/m 3 

### increments to determine which wind quadrant the highest ambient values were correlated with for all exceedance days.

### 32

Table 6: Hourly ambient PM 10 

### concentrations sorted by concentration and wind direction, 2007 - 2009 exceedance days.

Range of Ambient Concentration Values (microgram/m 3 )

Wind

Direction Quadrant < 150 150

- 250 250

-

350 350

-

450 450

-

550 >= 550 Share of All

Wind

Direction

Observations Northerly

NW to NNE 2 7 % 6% 3% 3 % 3 % 0% 17%

Easterly

NE to ESE 15% 16 % 16% 11 % 3 % 8% 14%

Southerly

SE to WSW 4 1 % 71% 72% 8 4 % 9 2 % 92% 5 7 %

Westerly

SW to WNW 1 8 % 6% 8% 3 % 3 % 0% 12%

Total 100 % 100% 100% 100% 100% 100% 100%



### As shown in Table 6, the largest proportions of hourly values above 150 g/m 3 

### in each ambient value increment are from the southerly wind direction quadrant. Also, the proportion of high ambient values in each concentration increment observed for the southerly quadrant exceed this quadrant’s share of all wind direction observations by 14 to 35 percent. In contrast, the proportion of high ambient values in each concentration increment for the other three wind direction quadrants are approximately equal to or less than their respective overall share of wind direction observations. The complete analysis

can be found in the file Nogales PM10 – Concentration and Met Analysis.xlsx

.

In the third analysis, for each of the exceedance days, PM 10 

### concentrations for hours associated with wind direction from the south (135 - 224 degrees) and all other directions (0 -134 degrees and 225-359 degrees) were averaged separately, with the results presented in Table 7. For one of the days, May 22, 2008, winds were entirely out of the southerly direction; therefore, no average concentration is calculated for the other direction assignment.

Table 7: Average PM 10 

### concentration for hours associated with wind direction from the south (135 - 224 degrees) versus all other directions for all exceedance days.

Date 24

- hour

Concentration Southerly Wind Quadrant

Concentration (135 to 224 degrees) All Other Wind

Direction

Concentration (225 to 134 degrees) Concentration Ratio of Southerly Wind Quadrant to Other

Wind Directions

1

- Jan

- 2007 210 199 231 0.86

6

- Feb

- 2007 180 228 100 2.28

6

- Mar

- 2007 157 265 66 4.02

15

- Mar

- 2007 175 360 65 5.54

19

- Oct

- 2007 189 335 43 7.79

27

- Oct

- 2007 210 301 133 2.26

2

- Nov

- 2007 211 278 79 3.52

3

- Nov

- 2007 170 213 128 1.66

### 33

4

- Nov

- 2007 170 183 148 1.24

6

- Nov

- 2007 186 209 119 1.76

18

- Nov

- 2007 167 277 38 7.29

19

- Nov

- 2007 177 216 63 3.43

28

- Nov

- 2007 167 278 75 3.71

24

- Dec

- 2007 233 368 45 8.18

26

- Jan

- 2008 204 257 182 1.41

27

- Feb

- 2008 166 251 66 3.80

18

- May

- 2008 169 356 57 6.25

22

- May

- 2008 217 217 No values observed

---
26

- Oct

- 2008 156 219 53 4.13

31

- Oct

- 2008 159 245 74 3.31

1

- Nov

- 2008 234 369 76 4.86

8

- Nov

- 2008 167 197 79 2.49

16

- Nov

- 2008 171 273 69 3.96

17

- Nov

- 2008 206 297 27 11.00

20

- Nov

- 2008 161 225 56 4.02

22

- Nov

- 2008 179 245 102 2.40

31

- Dec

- 2008 155 163 117 1.39

1

- Jan

- 2009 238 323 119 2.71

16

- Jan

- 2009 204 247 119 2.08



### Given that emissions and meteorological conditions may change throughout the day and we lack a continuous data stream of observations, this analysis examines whether it is possible that an exceedance would have occurred due to winds from directions other than from the southern quadrant. On two days, January 1, 2007 and January 26, 2008, average values from both the southern and all other wind quadrants exceed 150 g/m 3 

### , although on January 26, 2008, average concentrations from the southern quadrant remains higher

than the other directions. It should be noted that winds on all of these days, especially during periods of high concentration, were slow and variable. As such, it is possible that ambient concentrations came into the area from one direction and persisted as the wind direction changed.

3.7 Estimated 24-Hour Average Concentrations for Nogales NAA Under Meteorological Conditions Contributing to International Transport

In this analysis, each hourly concentration value from the 29 exceedance days in the 2007

- 2009 study period was classified based on the likely influence from Mexico according to four criteria or decision rules. An hourly concentration value so classified was then weighted by 0.36, representing the maximum proportion of Nogales NAA emissions compared to the total Ambos Nogales regional emissions and equivalent to assuming a 36 percent contribution from U.S. sources during those hours. Then, a 24-hour average

### 34

concentration was recalculated to determine what concentration would have occurred but for international transport of PM 10 

### emissions from Nogales, Sonora.

To begin, we classified each hour of the 29 exceedance days based on the likelihood of sig nificant international transport. An hourly concentration value was classified as influenced by international transport if it met one the following four criteria or decision rules related to hourly observations of wind direction, wind speed, and temperature change:

1) hours with sustained (more than one hour consecutively) southerly winds greater than 4.5 mph (two meters/second (m/s));

2) hours with southerly winds or air flow and decreasing or stable temperatures preceded by or followed by hours with similar conditions, suggesting sustained

down slope air flows from higher elevations south of the international border;.

3) any hour preceded by and followed by hours with southerly wind or air flow and decreasing or stable temperatures, suggesting continued influence of down slope

a ir flow from higher elevations south of the international border; and,

4) surface wind speed less than or equal to 1.1 mph (0.5 m/s), preceded by or followed by hours with similar conditions, suggesting sustained air mass stagnation where PM 10 

### emissions suspended in previous hours remain suspended in the stagnant air mass.

The first rule identifies periods consistent with sustained high winds from the south carrying wind-blown dust, as discussed earlier concerning the May 22, 2008 exceedance day. The second and third rules identify daily periods influenced by down slope wind flow conditions usually occurring in the late afternoon and evening, indicative of sustained down slope air flows from higher elevations south of the international border.

The fourth rule identifies periods of sustained air mass stagnation usually found in the late night and early morning hours after the early evening down slope wind or air flow has ebbed and before sunrise, after which wind speeds begin to increase from their

ove rnight low values.

The analysis of the Ambos Nogales emissions inventories concluded that U.S. sources are responsible for 18 - 36 percent of PM 10 

### emissions in the Ambos Nogales region, per the 2008 emission inventory figures shown below. 10

10 For a complete discussion of the Ambos Nogales emission inventories, see Appendix A: 2008 and 2011 Emissions Inventory for Nogales NAA and Appendix B: 2008 and 2011 Emissions Inventories for the Nogales Municipality, Sonora, Mexico.

### 35

Table 8: 2008 PM 10 

### Emission Inventories: Nogales NAA, Arizona and Nogales Municipality, Mexico (low estimate) (tons per year)

PM 10 Percent
Nogales NAA, Arizona 1,5 31 36 %
Nogales Municipality, Mexico 2,713 64 %

Total 4,2 44 100 %



### Table 9: 2008 PM 10 

### Emission Inventories: Nogales NAA, Arizona and Nogales Municipality, Mexico (high estimate) (tons per year)

PM 10 Percent

Nogales NAA, Arizona 1,5 31 1 8 %

Nogales Municipality, Mexico 6,98 7 82 %

Total 8,51 8 100 %



### Therefore, for each hour that meets one of the four criteria listed above, instead of categorizing that hourly concentration as due entirely to Mexican sources on the basis of a single variable such as wind direction, a more conservative assumption is that 36 percent of the hourly concentrations may be due to contributions from U.S. emission sources. For this analysis, we weighted the observed hourly concentrations by 0.36 for each hour that meets any one of the four criteria listed above and used this hourly

we ighted concentration to estimate the 24-hour average concentration that would have occurred in the Nogales NAA but for international transport.

To show the effects of each decision rule, an estimated 24-hour concentration was calculated after the application of Rule 1, Rules 2 and 3, Rules 1 - 3, and Rules 1 - 4. The

re sults are summarized below and provided in their entirety for all exceedance days in the

table that follows.

The application of Rule 1 only removes one day, 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 days; 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



### .

### 36

Table 10: Estimated 24-hour Average PM 10 

### Concentrations (μg/m 3 

### ) for 29 Exceedance Days Weighted According to Decision Rules for Mexican Influence

Date Observed Rule 1 Rules 2 &

3 Rules 1, 2,

& 3 Rules 1, 2,

3, & 4

1/1/2007 210.9 210.1 196.8 196.1 104.3

2/6/2007 180.3 180.3 115.4 115.4 106.9

3/6/2007 157.1 157.1 79.4 79.4 66.3

3/15/2007 176.0 176.0 94.4 94.4 76.8

10/19/2007 189.1 189.1 88.5 88.5 72.4

10/27/2007 210.1 208.6 114.2 114.2 88.2

11/2/2007 211.5 210.6 105.7 104.8 90.9

11/3/2007 170.9 170.9 110.7 110.7 77.9

11/4/2007 170.2 167.5 118.5 117.1 70.1

11/6/2007 186.6 180.3 101.9 101.9 77.4

11/18/2007 167.5 167.5 78.2 78.2 64.8

11/19/2007 177.6 176.5 100.7 99.7 78.4

11/28/2007 167.1 167.1 116.0 116.0 93.6

12/24/2007 233.3 233.3 124.3 124.3 89.5

1/26/2008 204.1 204.1 204.1 204.1 97.0

2/27/2008 166.0 166.0 99.1 99.1 63.9

5/18/2008 169.3 169.3 105.8 105.8 88.7

5/22/2008 217.4 78.3 145.7 78.3 78.3

10/26/2008 156.9 156.9 78.6 78.6 58.8

10/31/2008 159.7 159.7 89.9 89.9 64.9

11/1/2008 234.8 234.8 112.3 112.3 99.2

11/8/2008 167.7 166.3 85.8 85.1 70.5

11/16/2008 171.0 171.0 76.1 76.1 72.5

11/17/2008 206.7 206.7 107.3 107.3 107.3

11/20/2008 161.3 161.3 91.1 91.1 69.0

11/22/2008 179.6 177.3 95.8 93.6 69.5

12/31/2008 155.7 153.0 79.4 76.6 67.4

1/1/2009 238.4 238.4 122.7 122.7 88.7

1/16/2009 204.4 204.4 118.6 118.6 82.6

Values > 150 μg/m 3 29 28 2 2 0



### Considering the relatively large differences in emissions inventories in the Nogales NAA and Nogales, Sonora and the meteorology described by our conceptual model, it is likely that observed pollution during southerly down slope wind flows originating from Noga les, Sonora also contributed to observed pollution during following hours of

sust ained stagnation. With the wind direction varying under low wind speeds and stable temperatures, it remains possible, however, that a greater proportion of PM 10 

### pollution during those hours of sustained stagnation may be coming from U.S. sources. Therefore, a slightly more conservative approach would be to relax our criteria by not considering sustained stagnation (Rule 4) and assign PM 10 

### levels during these hours entirely to the Nogales NAA. Consequently, when we consider Mexican influence to only occur under conditions of relative high wind speeds (Rule 1) and sustained down slope wind flows from the south (Rules 2 and 3), two exceedance days would have been expected to occur

### 37

but for international transport: January 1, 2007 and January 26, 2008. In conclusion, this analysis demonstrates that at least 27 of 29, and possibly all 29 exceedances of the PM 10 

### NAAQS observed in the Nogales NAA during 2007 - 2009 can be attributed to sources of

PM 10 

### from across the international border.

The observed concentrations and meteorological data for each hour of each exceedanceday, the hourly concentration classification based on the criteria listed above, and the recalculation of the estimated 24-hour average concentrations based on the application of the four decision criteria are provided in the file Nogales PM10 – Concentration and Met Analysis.xlsx

.



## 4 .0 Discussion

4. 1 Disparity in Observed Ambient Values

4.1.1 Differences between Nogales, Arizona Post Office FEM and FRM

As is s hown in Tables 1 - 3, PM 10 

### concentrations reported by the Nogales, Arizona Post Office FRM on exceedance days are always lower than PM 10 

### concentrations reported by the co-located FEM. It is likely that the observed concentration differences are attributable to differences in monitoring methods, rather than quality assurance issues (see Section 2.3 for discussion of quality assurance review of these monitors). Data from the FEM, however, remains appropriate for comparison to the NAAQS.

4.1.2 Differences between Nogales, Arizona Ambient Values and Nogales, Sonora

Ambient Values

As is shown in Tables 1 - 3 above and Table 11 below, within the three-year dataset,

ther e were six days with both observed exceedances at the Nogales, Arizona Post Office FEM monitor and measurements at the Nogales, Arizona Post Office FRM and Nogales, Sonora Fire Station monitors. Observed concentrations at the Nogales, Sonora monitor are always lower than observed concentrations at the Nogales, Arizona Post Office FEM and, with one exception, lower than the observed concentrations at the Nogales, Arizona Post Office FRM. It is unlikely that the observed concentration differences are attributable to quality assurance issues (see Section 2.3), but it is possible that some of

the dif ferences in observed concentration could be attributable to differences in monitoring method.

### 38

Table 11: Six Exceedance Days Where Observations Exist for Nogales, Arizona

Monito rs and Nogales, Sonora Monitor: 24-hour concentrations (μg/m 3 

### ).

Date 24

- hour Concentration At

Nogales/AZ FEM BAM

1020 Monitor 24

- hour Concentration At Nogales/AZ FRM Partisol

Monitor 24

- hour Concentration At Nogales/Mexico Dicot

Monitor

27

- Oct

- 2007 210 122 159

2

- Nov

- 2007 211 190 170

18

- May

- 2008 169 147 126

8

- Nov

- 2008 167 155 119

20

- Nov

- 2008 161 150 126

1

- Jan

- 2009 238 Null 129



### Examining the six days of observations across the Arizona and Mexican monitors using the hourly observations at the Nogales, Arizona, FEM monitor we find the following: five of six days are consistent with the diurnal pattern observed for majority of exceedances (26 out of the 29); concentrations from the southerly wind μg/m 3 

### quadrant range from 197-356 μg/m 3 

### ; conc entrations from all other wind quadrants range from 56 - 133 μg/m 3 

### ; and, the concentration ratios are consistent with our estimated pollution load ratios. See Table 12, below.

Table 12: Six Exceedance Days Where Observations Exist for Nogales, Arizona Monitor

a nd Nogales, Sonora Monitor: Concentration Values Disaggregated by Southerly Wind Quadrant versus All Other Wind Directions (μg/m 3 

### ).

Date Consistent

With

Observed

Diurnal

Pattern?* 24

- hour

Concentration At Nogales,

AZ FEM

Monitor Southerly Wind

Quadrant

Concentration (135 to 224 degrees) All Other Wind

Direction s Concentration (225 to 134 degrees) Concentration Ratio of

Southerly Wind Quadrant to All Other

Wind Directions

27

- Oct

- 2007 Yes 210 301 (11 of 24 values) 133 2.26

2

- Nov

- 2007 Yes 211 278 (16 of 24 values) 79 3.52

18

- May

- 2008 Yes 169 356 (9 of 24 values) 57 6.25

8

- Nov

- 2008 Yes 167 197 (18 of 24 values) 79 2.49

20

- Nov

- 2008 Yes 161 225 (15 of 24 values) 56 4.02

1

- Jan

- 2009 Varies 238 323 (14 of 24 values) 119 2.71

* The diurnal pattern used for comparison is depicted in Figure 14 and is based on the 26 exceedance day hourly averages for ambient concentration, temperature and wind speed.



### Also, we examined elevation differences between the Nogales, Sonora monitoring site and the Nogales, Arizona monitoring site to determine if a difference might account for some of the observed differences in concentration. The two sites varied by approximately 45 feet in elevation with the Nogales, Sonora monitor at the higher elevation of 3920 feet. Because we are unable to visit the Nogales, Sonora monitoring

sit e, we are unable to evaluate further whether smaller scale and more local topographic

e ffects may be enhancing the disparity in observed values.

### 39

4. 2 Long Range Transport

As shown in Ta

bles 1 to 3, on days that the Nogales, Arizona Post Office monitor is exceeding, there are no observed PM 10 

### exceedances at the Green Valley, Arizona monitor, located between Nogales and Tucson, Arizona. On all days except May 22, 2008, the PM 10 

### concentrations observed at the Green Valley monitor are very low and did

not ex ceed 35 g/m 3 

### . Thus, it is unlikely that long range transport of PM 10 

### is occurring from the direction of Tucson on those days (noting that for May 22, 2008, winds were entirely from the south and thus not from the direction of the Green Valley, Arizona monitor).

4. 3 Local Sources Near Nogales, Arizona Monitor

We examined satellite and overhead photographs of an area within four kilometers surrounding the Nogales, Arizona Post Office monitoring site to determine if there were any local emission sources near enough to the monitor to greatly influence ambient PM 10 

### values. The aerial photographs showed vehicle track-out on to paved roads, unpaved roads and drives, and disturbed surfaces in open areas in the area surrounding the monitor; especially in areas to the east and south. We observed a small materials loading and storage operation very near to the monitor. With only contemporaneous aerial photography, however, we cannot confirm how long this operation has existed at this site, or the timing, duration, and magnitude of its operations during our 2007 - 2009 analysis

pe riod.

4. 4 Observations of Coarse Versus Fine Particulate Matter

Ex amining the ratio of PM 10 

### to PM 2.5 

### on exceedance days versus all monitored days provided information on the relative importance of sources that emit coarse particles (PM 10 -2.5 

### ) versus fine particles (PM 2.5 

### ) on those days. In addition to the Nogales, Arizona

Post Office PM 10 

### SPM-FEM, a PM 2 .5 

### SPM-FEM is operated at the same site (with the same AQS ID: 04-023-0004, POC 3). Monitored values from both monitors are compared in the file Nogales PM10 – Concentration and Met Analysis.xlsx . For 2007 through 2009, the average PM 10 

### :PM 2.5 

### ratio on all days with valid samples was 6.24 (standard deviation equals 2.89). For comparison, the PM 10 

### :PM 2.5 

### ratio for exceedance days is given in Table 13.

Table 13: Twenty-four Hour PM 10 

### and PM 2.5 

### concentrations ( g/m 3 

### ), and the ratio of

observed PM 10 

### :PM 2.5 

### on exceedance days at the Nogales, Arizona Post Office monitoring site (2007 - 2009).

Sample Date PM 10 

### (A) PM 2.5 

### (B) PM 10 /PM 2.5 (A/B)

1/1/2007 210 141 1.49

2/6/2007 180 28 6.43

3/6/2007 No paired data available

3/15/2007 No paired data available

### 40 10/19/2007 189 22 8.79

10/27/2007 210 26 8.20

11/2/2007 211 28 7.62

11/3/2007 170 25 6.85

11/4/2007 170 23 7.33

11/6/2007 186 23 8.05

11/18/2007 167 19 8.70

11/19/2007 177 21 8.31

11/28/2007 167 23 7.20

12/24/2007 233 72 3.26

1/26/2008 204 36 5.70

2/27/2008 166 17 9.88

5/18/2008 169 21 8.13

5/22/2008 217 20 10.96

10/26/2008 156 20 7.88

10/31/2008 No paired data available

11/1/2008 234 28 8.33

11/8/2008 167 23 7.42

11/16/2008 171 24 7.18

11/17/2008 206 24 8.58

11/20/2008 161 23 7.00

11/22/2008 179 28 6.39

12/31/2008 155 62 2.48

1/1/2009 238 142 1.67

1/16/2009 204 29 7.06



### With the exception of the four holidays (January 1 and December 24, 2007; December 31, 2008; and January 1, 2009) the ratio of PM 10 

### to PM 2.5 

### stays approximately the same or increases (noting a slight decrease to 5.7 on January 26, 2008, which is within a standard deviation of the average and could be considered as staying the same). On the four holidays, the ratio of PM 10 

### to PM 2.5 

### decreases by more than a standard deviation from the average ratio, suggesting an increase in a source of fine particles, such as

increased wood combustion. The ratio of PM 10 

### to PM 2 .5 

### increases by the greatest amount on May 22, 2008, which suggests that more coarse particles and/or different sources may be contributing to this exceedance.

### 41

4.5 Review of 2010 and 2011 Exceedance Days

For reasons discussed in Section 2.2, we chose 2007 - 2009 for our study period. Nonetheless, w e evaluated whether the exceedance days in 2010 and 2011 were

c onsistent with the diurnal pattern we observed for exceedance days in our 2007 - 2009

a nalyses. Also we did two analyses to determine if we would observe a contribution of high hourly ambient values from the southerly wind direction quadrant similar to what

we observed over the 2007 - 2009 exceedance days.

F or the monitoring data reported as of the time of this analysis, i.e., through the third quarter of 2011, there were seven reported PM 10 

### exceedance days in 2010 and 2011: December 2, 3, 4, 5, 8, and 13, 2010; and September 23, 2011. Figures 20 and 21 show the hourly PM 10 

### concentration and wind speed, respectively, for those seven days versus the average PM 10 

### concentration and wind speed for the 2007 - 2009 exceedances (from

F igure 14). Wind speed data for 2011 is not yet available; consequently, September 23, 2011 was not included in Figure 21.

Figure 20: Hourly PM 10 

### concentrations at the Nogales, Arizona Post Office FEM monitor versus time of day for all exceedances between January 1, 2010 and September 30, 2011 compared to average PM 10 

### concentrations from Figure 14 (2007 - 2009).

0 100 200 300 400 500 600 700 8000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00PM10 Concentration Average for 2007

- 2009 Exceedances

12/2/2010
12/3/2010
12/4/2010
12/5/2010
12/8/2010
12/13/2010
9/23/2011

### 42

Figure 21: Hourly wind speed at the Nogales, Arizona Post Office FEM monitor versus time of day for all exceedances in 2010 compared to average wind speed from Figure 14 (2007 - 2009).

F or the six 2010 exceedance days, we performed two additional meteorological analyses to determine if we would observe a contribution of high hourly ambient values from the southerly wind direction quadrant similar to what we observed over the 2007 - 2009

e xceedance days. These analyses are similar to those described in Section 3.6 concerning hourly ambient concentrations and wind direction. Again, September 30, 2011 was not included in these analyses because wind speed and direction data are not yet available for

2011.

In the first analysis, on 2010 exceedance days, we determined that 87.6 percent of the

o bserved 24-hour PM 10 

### concentration is attributable to winds from the south, i.e., 135 - 224 degrees. The remainder of the 24-hour PM 10 

### concentration is attributed to: east, 45 - 134 degrees, 5.9 percent; west, 225 - 314 degrees, 1.5 percent; and north, 315 - 44 degrees, 4.9 percent.

For the second analysis, we averaged the observed PM 10 

### concentration associated with winds from the south versus all other directions for each exceedance day; see Table 14

be low (comparable to Table 7 for 2007 - 2009). Only December 4, 2010 had an hourly

a verage PM 10 

### concentration above 150 g/m 3 

### from directions other than southerly wind quadrant. A closer examination of hourly concentrations, wind speed, and wind direction on December 4, 2010, however, indicates that this is due largely to an anomaly of the

mid -day low concentrations being attributable to southerly wind flow; an event not usually observed on most exceedance days. This results in the averaging of a relatively small number of hours for all other wind directions quadrant only during the high concentration, stagnant wind conditions in the early morning and late evening. 0 1 2 3 4 5 6 7 80:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00Wind Speed (mph) Average for 2007

- 2009 Exceedances

12/2/2010
12/3/2010
12/4/2010
12/5/2010
12/8/2010
12/13/2010

### 43

Table 14: Average PM 10 

### concentration for hours associated with wind direction from the south (135 - 224 degrees) versus all other directions for 2010 exceedance days.

Date 24

- hour

Concentration Southerly Wind Quadrant

Concentration (135 to 224 degrees) All Other Wind

Direction

Concentration (225 to 134 degrees) Concentration Ratio of Southerly Wind Quadrant to Other

Wind Directions

2

- Dec

- 2010 177 188 57 3.33

3

- Dec

- 2010 161 172 108 1.59

4

- Dec

- 2010 191 184 215 0.86

5

- Dec

- 2010 163 242 31 7.88

8

- Dec

- 2010 159 245 40 6.19

13

- Dec

- 2010 175 245 60 4.08



### To conclude, the screening analysis of the seven reported exceedances between January 1, 2010 and September 30, 2011, shows that all of these exceedances are consistent with observed exceedances during the 2007 - 2009 period. Only December 4, 2010 potentially

de viates from the majority of exceedance days. Again, we observed a small number of wind direction observations from the all other wind direction quadrants were associated with high PM 10 

### concentrations, leading to an average 215 g/m 3 

### PM 10 

### concentration attributed to the non-southerly wind direction quadrants. However, even this exceedance is likely similar to the 2007 - 2009 observations and, with further analysis, may be

a ttributable to emissions from Nogales, Sonora, Mexico. Therefore, the conclusions reached in the more sophisticated analysis of 2007 - 2009 exceedances are likely to be

a pplicable to 2010 - 2011 exceedances as well, based on this screening analysis of the incomplete data during the later period.



## 5.0 Conclusions

From this review and analysis of the Nogales NAA ambient PM 10 

### data, local meteorology, and topography, we draw the conclusions listed below.

The majority of exceedances, 79 percent, occur in the October to January timeframe, mostly in November. Also, given the high desert environment and winter light regime, temperatures usually drop dramatically, 20 degrees

Fahrenheit over the 3-4 hours after sunset.

Elevations drop 709 feet over 14.8 miles across the south to north local transect we examined, from the southern boundary of Nogales, Sonora to the northern boundary of the Nogales NAA.

Of the 29 exceedance days in 2007 - 2009, twenty-six of those days showed a

sim ilar pattern of ambient PM 10 

### concentration, wind speeds, wind direction, and temperature variation over a twenty-four hour period; the three exceptions were January 1, 2007, May 22, 2008, and January 1, 2009.

### 44 On exceedance days, the largest proportions, 71-92 percent, of hourly values exceeding 150 g/m 3 

### and almost all of the highest observed PM 10 

### concentrations, 92 percent of observations above 450 g/m 3 

### , are associated with a southerly wind

direction.

On all 29 exceedance days, the ambient PM 10 

### concentration attributed to the southerly wind quadrant exceeds 150 g/m 3 

### . In contrast, two exceedance days from the “all other wind direction” quadrants show a value greater than 150 g/m 3 

### : January 1, 2007, and January 26, 2008.

Only one of 29 exceedance days shows a concentration attributed to the “all other wind direction” quadrants greater than that of the concentration attributed to the southerly wind quadrant: January 1, 2007.

The average ratio of the southerly wind quadrant share of 24-hour ambient PM 10 

### values to all other wind quadrants share of ambient values is 3.83 to one.

Considering relative high wind speeds, sustained down slope wind flows from the south, and sustained air stagnation, an analysis of hourly concentration values shows that at least 27 of 29, and possibly all 29 exceedances of the PM 10 

### NAAQS observed in the Nogales NAA during 2007 - 2009 can be attributed to sources of

PM 10 

### from across the international border. The two exceedance days that would have been expected to occur were January 1, 2007 and January 26, 2008.

On most exceedance days, the ratio of PM 10 

### to PM 2.5 

### increases or stays the same compared to the average ratio for all days in 2007 - 2009. The exceptions are four

holi days where the ratio of PM 10 

### to PM 2.5 

### on exceedance days decreases, indicating increased importance of a combustion source.Appendix E ADEQ Technical Support Document for Co ntrol Measure Emissions Reductions

This appendix contains ADEQ's Technical S upport Document (TSD) and four supporting appendices. The TSD provides detail ed explanation for estimated PM 10 emissions reductions resulting from paving/double chip-sealing unpaved roads in the Nogales Nonattainment Area (Nogales NA). Appendix E.1 provides data used to estimate the number of annual vehicle miles traveled on applicable roads in the Nogal es NA. Appendix E.2 includes paving/double chipsealing documentation provided by Santa Cruz Count y. Appendix E.3 includes a map created by ADEQ using the latest geographic information sy stems (GIS) data to de pict paved and unpaved roads in the Nogales NA that are not within N ogales' city limits, and ADEQ's estimated mileage for both road types. Appendix E.4 includes before and after aerial imagery of roads paved/double chip-sealed in the Nogales NA.This page is intentionally blank.

### 1 Appendix E



### ADEQ Technical Support Document for Control Measure Emission Reductions

E.1. Emissions Reductions from Roads Paved in Rio Rico, AZ from 2002-2008

When ADEQ submitted the 1993 SIP for the Nogal es Nonattainment Area (NA), most roads in the portions of Rio Rico in the nonattainment area were paved, but the community grew at a steady pace from that point. From 1994-2001, Sa nta Cruz County double-chip sealed or paved approximately 40 miles of roads in Rio Rico, both in and near the Nogales NA. 1

Santa Cruz County was able to provide records fo r 39.8 miles of roads chip sealed in Rio Rico between the years 2002-2008. Documentation provided by the County is in Appendix 2 of this document. Of these 39.8 miles of chip sealed road ways, 8.6 miles were found to be located within Rio Rico in the Nogales NA; Table E.1 includes th e road names, year chip sealed, road length and mileage chip-sealed.

Table E.1 Road Mileage Chip Sealed in Rio Rico Since 2002

Roadway Year Paved Road Length [mi]* Reported Mileage Paved **

Calle Arikara 2002 1.09 1

Paseo Mexico 2004 4.03 2.6 Calle Coyote- Annette Ct 2006 1.92 2

Paseo Guebabi 2006 2.70 3

Total 9.75 8.6

* Calculated from aerial photography **Provided by Santa Cruz County

To estimate the emission reductions provided by 8.6 miles of chip sealing in Rio Rico, ADEQ estimated Annual Average Daily Traffic (A ADT) for unpaved roadways by using aerial photography of the region to digitize roadways an d categorize them as paved or unpaved. The number of homes on each unpaved roadway was also determined from aerial photography. Utilizing U.S. Department of Transportation data , we estimated vehicle trips per household for the Rio Rico Area as 1981 trips per year. This was calculated using the following methodology:

T p = Average Person trips by household = 3466 (U.S. Dpt. of Transportation, 2011, Table 5)

T V = Average Vehicle trips by household = 2068 (U.S. Dpt. of Transportation, 2011, Table 6)

SF = Scaling Factor = T V / T P = 2068 / 3466 = 60%

Rio Rico CDP median household income = $43,805 (US Census State and County Quickfacts, median HH income for Santa Cruz County, Rio Rico CDP 2006-2010)

T PHH = Person trips by household income = 3321 (U.S. Dpt. of Transportation, 2011, Table 8; per Rio Rico household income)

1 Santa Cruz County is unable to locate chip s ealing records for 1994-2002; ADEQ did receive written confirmation of the mileage estimation from County officials. See Appendix G – Supplementary

Information

### 2 According to the U.S. Department of Transpor tation for a median income of $43,805 (median income of Rio Rico) the household has an income of 3321 trips per year.

Vehicle trips by household income = T PHH * SF = 3321 * 60% = 1981

If we assume the national trips taken were appr oximately the same for the year 2008, we can estimate VMT for individual unpaved roads using the calculated vehicle trips by household by implementing the following methodology:



##  

XX X X 

### TH L VMT **5280/*5.0 

Where:

VMT X = Vehicle Miles Traveled for a particular roadway, X [miles]

0.5 = Adjustment ratio to account for the locati on of houses along a road length and the distance

needed to travel to exit the ro adway. It is assumed that on average a vehicle must travel an average of one quarter of the road length before it exits the roadway and will make this trip 2 times (once upon leaving and once upon returning) to the residence.

L X = Length of roadway X [ft]

5280 = conversion factor from feet to miles [ft/mile]

H X = the number of homes located on roadway X

T X = Average annual trips per household = 1981

Table E.2 Calculated VMT for Chip-Sealed Roadways in Rio Rico for 2009

Roadway Road Length [mi] Household Vehicle Trips

Taken Households VMT

Calle Arikara 1.09 1981 21 22694

Paseo Mexico 4.03 1981 49 195774 Calle Coyote- Annette Ct 1.92 1981 46 65678

Paseo Guebabi 2.70 1981 63 168746

Total 9.74 7924 179 452893

Using the method outlined above, total VMT for unpaved roadways and chip-sealed roadways within the Rio Rico portion of the Nogales NA was found to be 968,460 miles (Appendix E .1) and 452,893 miles respectively (Table E. 2). In order to calculate total PM 10 emissions from unpaved roadways, ADEQ calculated unpaved road emission factors for a range of possible surface material silt contents within the Nogal es NA using equations 1(b) and 2 from EPA AP-42

5 th Ed. Volume 1 Chapter 13.2.2. A low surface ma terial silt content value of 2.90% and a high

surface material silt content value of 7.50% we re utilized per EPA recommendation and based on the Mexican NEI (2004) and the Mexicali Emission Inventory (2005). These calculations are

shown below:

### 3 

#    

  C M Ss k
E

c d a



###  

5.0 3012

Where:

E = PM 10 emission factor (lb/VMT) = 0.248 lb/VMT (low value) & 0.642 lb/VMT (high value)

k = Empirical Constant = 1.8 lb/VMT (EPA AP-42 Chapter 13.2.2, 2006)

s = surface material silt content (%) = 2.90 % and 7.50 % (recommended by EPA and based on the Mexican NEI – 2004 and the Mexicali Emission Inventory - 2005).

M = surface material moisture content (%) = 5.23 % (No reliable surface soil moisture measurements are known for the area. Therefore, the average 2 inch depth soil moisture from Walnut Gulch, AZ NRCS Site # 2026 for the year of 2008 of 4.30% was adjusted for Nogales, AZ based on the average annual difference in rainfall between the tw o locations of 21.5% [Balling, 1988])

S = mean vehicle speed (mph) = 25 mph (Based on the typical unpaved road speed limit in Arizona)

a = Empirical Constant = 1 (EPA AP-42 Chapter 13.2.2, 2006)

c = Empirical Constant = 0.2 ( EPA AP-42 Chapter 13.2.2, 2006)

d = Empirical Constant = 0.5 (EPA AP-42 Chapter 13.2.2, 2006)

C = 0.00047 lb/VMT (EPA AP-42 Chapter 13.2.2, 2006)

This emission factor was then corrected to only account for non-rainy days:



##   

##  

365/365 PEE

est 

### 

Where:

E est = annual size-specific emission factor extrap olated for natural mitigation (lb/VMT) = 0.217 lb/VMT (low value) & 0.563 lb/VMT (high value)

E = the unadjusted emission factor = 0.248 lb/VMT (low value) & 0.642 lb/VMT (high value)

P = number of days in a year with at least 0.254 mm (0.01 in) of precipitation = 45 days (EPA AP-42 Figure 13.2.2-1., 2006)

Using the above calculated emission factors of 0.217 lb/VMT and 0.563 lb/VMT, and the total VMT of 968,460 miles for all unpaved roadways in the Rio Rico portion of the Nogales NA, ADEQ calculated total emissions from unpaved roadways to be:



##       tonlb VMTlb miles EVMTE EST

Low 

### /2000//217.0* 968,460 2000/*   = 105 tons 

##       tonlb VMTlb miles EVMTE EST

High 

### /2000//563.0* 968,460 2000/*   = 273 tons

Therefore, the total PM 10 emissions from unpaved roads within the Rio Rico portion of the Nogales NA are estimated to be between 105 and 273 tons.

### 4 According to Santa Cruz County officials, a double layer of chip-seal was applied to the roadways in the Rio Rico portion of the Nogales NA listed in Table E.1. This type of paving has been estimated as having a control efficiency of approximately 90% if it is combined with paved shoulders, curbs and gutters (Engineering Scie nce, 1987). In order to determine the PM 10 emission reductions observed from the chip-sealing of the roadways previously mentioned, two separate methods of calculating emissions from chip sealed roadways are presented below. The

two emission estimates differ in the control e fficiency utilized for the chip-sealing with: Method

1 ) utilizing 90% control efficiency for chip-sealed areas and Method 2 ) utilizing a paved road emission factor for the chip-sealed areas where th e paved road emission factor was calculated by utilizing Eq. 2 from AP 42: 13.2.1-5 (EPA, 2011).

METHOD 1 (M1)

Method 1 utilized 90% control efficiency for tho se roadways which have been chip-sealed. Table E.3 presents the calculated emissions from th ese roadways assuming no control measures were utilized (41 tons/yr PM 10 emitted when utilizing E EST-Low and 107 tons/yr PM 10 emitted when utilizing E EST-High ) and assuming all roadways were chip-sealed resulting in 90% control efficiency (4.1 tons/yr PM 10 emitted when utilizing E EST-Low and 10.7 tons/yr PM 10 emitted when utilizing E EST-High ). In those cases where the entire road length was not chip-sealed, VMT (and

thus PM 10 emissions) was adjusted for the percen tage of roadway which was chip-sealed.

Table E.3

Calculated PM 10 Emissions Assuming 90% Chip-Seal Efficiency

Roadway VMT Unpaved Emissions, Low [tons] Unpaved Emissions, High [tons] Chip-sealed Emissions, Low [tons] Chip-sealed Emissions, High [tons]

Calle Arikara 22694 2.3 5.9 0.23 0.59

Paseo Mexico 195774 13.7 35.5 1.37 3.55Calle CoyoteAnnette Ct 65679 7.1 18.5 0.71 1.85

Paseo

Guebabi 168746 18.3 47.5 1.83 4.75

Total 452893 41.4 107.4 4.14 10.7

METHOD 2 (M2)

Method 2 assumed double chip-sealed roadways would produce emission reductions to the same degree as asphalt paved roadways. Therefore, an emission factor was calculated for the paved roadways using Eq. 2 from AP 42: 13.2.1-5 ( EPA, 2011). This calculation is shown below:



##    

#   

#  

N P WsLkE 4 1 02.1 91.0 

### 

Where:

E = annual average emission factor = 0.000841 lbs/VMT

### 5 k = particle size multiplier for particle size range and units of interest = 0.0022 lbs/VMT (Table 13.2.1-1. from AP-42, EPA 2011)

sL = road surface silt loading = 0.105 g/m 2 (Assumed to be comparable to an average silt loading

value measured from local traffic roads in Tabl e 3, page 28 of Phoenix Airshed Particulate Emissions study, Arizona State University 2006)

W = average weight of the vehicles traveling the road = 3 tons (Arizona State University 2006, pg. 27)

P = number of "wet" days with at least 0.254 mm (0.01 in) of precipitation during the averaging period = 45 days (EPA AP-42 Figure 13.2.2-1., 2006)

N = number of days in the averaging period = 365 days

The calculated emission factor does not account for brake wear and tire wear emissions and thus, EPA’s Motor Vehicle Emission Simulator (EPA MOVES2010a, 2009) was run for the year of 2008 for Santa Cruz County in order to estimate an emission factor for these processes at the county level. This emission factor was then a dded to the paved roadway emission factor above (0.000841 lbs/VMT). MOVES calculated an emission factor of 0.000220 lbs/VMT. When the 2 emission factors are summed a total emission factor of 0.00106 lbs/VMT is calculated for paved roads in the Nogales NA.

Table E.4 presents the emissions from these roadways assuming no control measures were utilized (41 tons/yr PM 10 emitted when utilizing E EST-Low and 107 tons/yr PM 10 emitted when utilizing E EST-High ) and assuming all roadways were chip-sealed with a paved road emission factor of 0.00106 lbs/VMT (0.202 tons/yr PM 10 emitted when utilizing E EST-Low and E EST-High ). In those cases where the entire road length w as not chip-sealed, VMT (and thus PM 10 emissions) was adjusted for the percentage of roadway which was chip-sealed.

Table E.4

Calculated PM 10 Emissions Assuming Paved Road Efficiency

Roadway VMT Unpaved Emissions, Low [tons] Unpaved Emissions, High [tons] Paved Road Emissions [tons]

Calle Arikara 22694 2.3 5.9 0.011

Paseo Mexico 195774 13.7 35.5 0.067Calle CoyoteAnnette Ct 65679 7.1 18.5 0.035

Paseo Guebabi 168746 18.3 47.5 0.089

Total 452893 41.4 107.4 0.202

From the results calculated in Methods 1 and 2 (Tables E.3 and E.4). We can assume that the application of chip-seal to the 5 roadwa ys listed resulted in the reduction of PM 10 emissions between 37.3 and 41.2 tons per year assuming lo w unpaved road silt content value of (2.90 %) and between 96.7 and 107 tons per year assuming a high unpaved road silt content value of (7.50 %). Conservatively, we can assume that chip-sealing the roadways reduced PM 10 emissions within the region by 37.3 tons per year.

### 6 E.2. Emissions Reductions from Roads Paved in Nogales, AZ from 1987-1996

During analysis of aerial photography of the N ogales, AZ portion of the Nogales NA, ADEQ determined 11 roadways had been chip sealed between the years of 1992 and 1996. Those roadways identified are presented in Table E.5. PM 10 emissions reductions due to the paving of these roadways are presented in this section. ADEQ did not include this measure to demonstrate attainment in the 1993 Nogales NA SIP; therefor e, ADEQ is identifying this chip sealing as a control measure implemented in the Nogales NA.

Table E.5 Road Mileage Paved in Nogales Prior to 1996 Roadway Year Paved Road Length [mi]* Royal Rd 92-96 0.9

Vista del Cielo 92-96 2.2

Hohokam 92-96 .17 La Quinta 92-96 .75

Yucca Drive S. 92-96 2.0

Bristol Dr 92-96 .40 Target Range Rd 92-96 0.2

Frank Reed Rd 92-96 .95

Kino Rd 92-96 .28 Kelsey Rd 92-96 .27

West 1st St 92-96 .32

Total 8.4 Miles

* Calculated from aerial photography

To estimate the emission reductions provided by 8. 4 miles of chip sealing in Nogales, Arizona, ADEQ estimated Annual Average Daily Traffic (AADT) for unpaved roadways by using aerial photography of the region to digitize roadways an d categorize them as paved or unpaved. The number of homes on each unpaved roadway was also determined from aerial photography. Utilizing 2009 U.S. Department of Transportation data, we estimat ed vehicle trips per household for the Nogales Area as 1712 trips per year. This was calculated using the following methodology:

T p = Average Person trips by household = 3466 (U.S. Dpt. of Transportation, 2011, Table 5)

T V = Average Vehicle trips by household = 2068 (U.S. Dpt. of Transportation, 2011, Table 6)

SF = Scaling Factor = T V / T P = 2068 / 3466 = 60%

Nogales, AZ median household income = $29,44 2 (US Census State and County Quickfacts, median HH income for Nogales (City), 2010)

T PHH = Person trips by household income = 2,854 (U.S. Dpt. of Transportation, 2011, Table 8; per Nogales household income)

According to the U.S. Department of Transpor tation for a median income of $29,442 (median income of Nogales) the household has an income of 2,854 trips per year.

Vehicle trips by household income = T PHH * SF = 2854 * 60% = 1,712

### 7 If we assume the national trips taken were appr oximately the same for the year 2008, we can estimate VMT for individual unpaved roads using the calculated vehicle trips by household by implementing the following methodology:



##  

XX X X 

### TH L VMT **5280/*5.0 

Where:

VMT X = Vehicle Miles Traveled for a particular roadway, X [miles]

0.5 = Adjustment ratio to account for the locati on of houses along a road length and the distance

needed to travel to exit the ro adway. It is assumed that on average a vehicle must travel an average of one quarter of the road length before it exits the roadway and will make this trip 2 times (once upon leaving and once upon returning) to the residence.

L X = Length of roadway X [ft]

5280 = conversion factor from feet to miles [ft/mile]

H X = the number of homes located on roadway X

T X = Average annual trips per household = 1712

Table E.6 Calculated VMT for Chip-Sealed Roadways in Nogales Prior to 1996
Roadway Road Length [mi] Household Vehicle Trips Taken Homes VMT Royal Rd 0.9 1,712 21 16178

Vista del Cielo 2.2 1,712 85 160072

Yucca Drive S. 2 1,712 8 13696

Bristol Dr 0.4 1,712 23 7875

Frank Reed Rd 0.95 1,712 77 62616

Kino Rd 0.28 1,712 16 3835 Kelsey Rd 0.27 1,712 27 6240

West 1st St 0.4 1,712 20 6848

Total 257 277360

Roadway Road Length [mi] AADT VMT Target Range Rd 0.2 6468 1294

Total 278654

Using the method outlined above, total VMT for resi dential chip-sealed roadways within Nogales was found to be 277,361 miles. Three other roadwa ys were also identified as being chip sealed within Nogales. These roadways are listed below:

1. Hohokam Dr - Public Roadway (Commercial)

2. La Quinta Rd - Industrial Roadway

3. Target Range Road – Public Ro adway (Commercial/Residential)

Due to incomplete AADT datasets for this region, only an AADT for Target Range Rd could be identified (6468). No AADT data was available for Hohokam Dr and La Quinta Rd. Since these roadways were commercial/industrial roadways, AADT could not be estimated in the same

### 8 manner as the residential roadways. For these reasons, VMT was not calculated for Hohokam Dr. and La Quinta Rd. VMT calculation for Target Range Road can be accomplished by multiplying AADT by road segment length (0.2 miles) resulting in a VMT of 1294.

In order to calculate total PM 10 emissions from unpaved roadways, ADEQ calculated unpaved road emission factors for a range of possible surf ace material silt contents within the Nogales NA using equations 1(b) and 2 from EPA AP-42 5 th Ed. Volume 1 Chapter 13.2.2. A low surface material silt content value of 2.90% and a high su rface material silt content value of 7.50% were utilized per EPA recommendation and based on the Mexican NEI (2004) and the Mexicali Emission Inventory (2005). These calculations are shown below: 

#    

  C M Ss k
E

c d a



###  

5.0 3012

Where:

E = PM 10 emission factor (lb/VMT) = 0.248 lb/VMT (low value) & 0.642 lb/VMT (high value)

k = Empirical Constant = 1.8 lb/VMT (EPA AP-42 Chapter 13.2.2, 2006)

s = surface material silt content (%) = 2.90 % and 7.50 % (recommended by EPA and based on the Mexican NEI – 2004 and the Mexicali Emission Inventory - 2005).

M = surface material moisture content (%) = 5.23 % (No reliable surface soil moisture measurements are known for the area. Therefore, the average 2 inch depth soil moisture from Walnut Gulch, AZ NRCS Site # 2026 for the year of 2008 of 4.30% was adjusted for Nogales, AZ based on the average annual difference in rainfall between the tw o locations of 21.5% [Balling, 1988])

S = mean vehicle speed (mph) = 25 mph (Based on the typical unpaved road speed limit in Arizona)

a = Empirical Constant = 1 (EPA AP-42 Chapter 13.2.2, 2006)

c = Empirical Constant = 0.2 (EPA AP-42 Chapter 13.2.2, 2006)

d = Empirical Constant = 0.5 (EPA AP-42 Chapter 13.2.2, 2006)

C = 0.00047 lb/VMT (EPA AP-42 Chapter 13.2.2, 2006)

This emission factor was then corrected to only account for non-rainy days:



##   

##  

365/365 PEE

est 

### 

Where:

E est = annual size-specific emission factor extrap olated for natural mitigation (lb/VMT) = 0.217 lb/VMT (low value) & 0.563 lb/VMT (high value)

E = the unadjusted emission factor = 0.248 lb/V MT (low value) & 0.642 lb/VMT (high value)

P = number of days in a year with at least 0.254 mm (0.01 in) of precipitation = 45 days (EPA AP-42 Figure 13.2.2-1., 2006)

### 9 Using the above calculated emission factors of 0.217 lb/VMT and 0.563 lb/VMT, and the total VMT of 278,655 miles for public, chip sealed roadways in the Nogales, ADEQ calculated total emissions from unpaved roadways to be:



##       tonlb VMTlb miles EVMTE EST

Low 

### /2000//217.0*655,7822000/*   = 30.2 tons 

##       tonlb VMTlb miles EVMTE EST

High 

### /2000//563.0* 278,655 2000/*   = 78.4 tons

Therefore, the total PM 10 emissions from public, chip sealed roadways in Nogales prior to paving

are estimated to be between 30.2 and 78.4 tons.

A double layer of chip-seal was applied to those N ogales roadways listed in Table E.5. This type of paving has been estimated as having a contro l efficiency of approximately 90% if it is combined with paved shoulders, curbs and gutte rs (Engineering Science, 1987). In order to

determine the PM 10 emission reductions observed from the chip-sealing of the roadways previously mentioned, two separate methods of calculating emissions from chip sealed roadways are presented below. The two emission estimates differ in the control efficiency utilized for the chip-sealing with: Method 1 ) utilizing 90% control efficien cy for chip-sealed areas and Method

2 ) utilizing a paved road emission factor for the chip-sealed areas where the paved road emission factor was calculated by utilizing Eq. 2 from AP 42: 13.2.1-5 (EPA, 2011).

METHOD 1 (M1)

Method 1 utilized 90% control efficiency for tho se roadways which have been chip-sealed. Table E.7 presents the calculated emissions from th ese roadways assuming no control measures were utilized (30.2 tons/yr PM 10 emitted when utilizing E EST-Low and 78.4 tons/yr PM 10 emitted when utilizing E EST-High ) and assuming all roadways were chip-sealed resulting in 90% control efficiency (3.02 tons/yr PM 10 emitted when utilizing E EST-Low and 7.84 tons/yr PM 10 emitted when utilizing E EST-High ).

Table E.7

Calculated PM 10 Emissions Assuming 90% Chip-Seal Efficiency

Roadway VMT Unpaved Emissions, Low [tons] Unpaved Emissions, High [tons] Chip-sealed Emissions, Low [tons] Chip-sealed Emissions, High [tons]

Royal Rd 16178 1.76 4.55 0.176 0.455

Vista del Cielo 160072 17.37 45.06 1.737 4.506

Yucca Drive S. 13696 1.49 3.86 0.149 0.386

Bristol Dr 7875 0.85 2.22 0.085 0.222

Frank Reed Rd 62616 6.79 17.63 0.679 1.763

Kino Rd 3835 0.42 1.08 0.042 0.108 Kelsey Rd 6240 0.68 1.76 0.068 0.176

West 1st St 6848 0.74 1.93 0.074 0.193 Target Range Rd 1294 0.14 0.36 0.014 0.036

Total 278655 30.2 78.4 3.02 7.84

### 10 METHOD 2 (M2)

Method 2 assumed double chip-sealed roadways wo uld produce emission reductions to the same degree as asphalt paved roadways. Therefore, an emission factor was calculated for the paved roadways using Eq. 2 from AP 42: 13.2.1-5 ( EPA, 2011). This calculation is shown below:



##    

#   

#  

N P WsLkE 4 1 02.1 91.0 

### 

Where:

E = annual average emission factor = 0.000841 lbs/VMT

k = particle size multiplier for particle size range and units of interest = 0.0022 lbs/VMT (Table 13.2.1-1. from AP-42, EPA 2011)

sL = road surface silt loading = 0.105 g/m 2 (Assumed to be comparable to an average silt loading

value measured from local traffic roads in Tabl e 3, page 28 of Phoenix Airshed Particulate Emissions study, Arizona State University 2006)

W = average weight of the vehicles traveling the road = 3 tons (Arizona State University 2006, pg. 27)

P = number of "wet" days with at least 0.254 mm (0.01 in) of precipitation during the averaging period = 45 days (EPA AP-42 Figure 13.2.2-1., 2006)

N = number of days in the averaging period = 365 days

The calculated emission factor does not account for brake wear and tire wear emissions and thus, EPA’s Motor Vehicle Emission Simulator (EPA MOVES2010a, 2009) was run for the year of 2008 for Santa Cruz County in order to estimate an emission factor for these processes at the county level. This emission factor was then a dded to the paved roadway emission factor above (0.000841 lbs/VMT). MOVES calculated an emission factor of 0.000220 lbs/VMT. When the 2 emission factors are summed a total emission factor of 0.00106 lbs/VMT is calculated for paved roads in the Nogales NA.

Table E.8 presents the emissions from these roadways assuming no control measures were utilized (30.2 tons/yr PM 10 emitted when utilizing E EST-Low and 78.4 tons/yr PM 10 emitted when utilizing E EST-High ) and assuming all roadways were chip-sealed with a paved road emission factor of 0.00106 lbs/VMT (0.148 tons/yr PM 10 emitted when utilizing E EST-Low and E EST-High ).

### 11 Table E.8

Calculated PM 10 Emissions Assuming Paved Road Efficiency

Roadway VMT Unpaved Emissions, Low [tons] Unpaved Emissions, High [tons] Paved Road

Emissions [tons] Royal Rd 16178 1.76 4.55 0.0086

Vista del Cielo 160072 17.37 45.06 0.0848

Yucca Drive S. 13696 1.49 3.86 0.0073

Bristol Dr 7875 0.85 2.22 0.0042

Frank Reed Rd 62616 6.79 17.63 0.0332

Kino Rd 3835 0.42 1.08 0.0020 Kelsey Rd 6240 0.68 1.76 0.0033

West 1st St 6848 0.74 1.93 0.0036 Target Range Rd 1294 0.14 0.36 0.0007

Total 278655 30.2 78.4 0.148

From the results calculated in Methods 1 and 2 (Tables E.7 & E.8). We can assume that the application of chip-sealing to the 9 road ways listed resulted in the reduction in PM 10 emissions between 27.2 and 30.1 tons per year assuming lo w unpaved road silt content (2.90 %) and 70.6 and 78.3 tons per year assuming a high unpaved ro ad silt content (7.50 %). Conservatively, we can assume that chip-sealing the roadways reduced PM 10 emissions within Nogales, AZ by 27.2
tons per year.

Results

This Technical Support Document (TSD) presents control measures for the Nogales NA which are already implemented and calculates the resultant PM 10 emission reductions of these measures. Between 1992 and 2008, 17.0 combined miles of road way were chip sealed in the Rio Rico and Nogales portions of the Nogales NA. In this TSD, ADEQ presented 2 methods of calculating emission reductions for these chip sealed roadways, whereby emission reductions were calculated by: Method 1 ) Assuming chip sealing provides 90% control efficiency of emissions and Method

2 ) assuming chip sealing provides emissions ra tes equivalent to paving the roadways. Furthermore, emission rates were calculated for a range of surface silt contents between 2.9 %

and 7.5 % to account for unknown and variable soil silt contents within the region. These calculations resulted in a range of PM 10 emissions reductions for the Nogales NA (i.e. a combination of Rio Rico and Nogales emission re ductions) of 64.5 - 71.3 tons/year assuming low surface soil silt content and 167 – 185 tons/year assuming high surface soil silt content for those areas surrounding the 14 chip sealed roadways identified in this st udy. Therefore, a conservative

estimate of the emission reductions within th e Nogales NA, due to chip sealing of these roadways, would be 64.5 tons/year.

### 12 REFERENCES

“2005 Mexicali Emissions Inventory”, Final Report, February 27, 2009, Eastern Research Group, Inc. (ERG).

Arizona State University (ASU), 2006. A FIELD STUDY OF PARTICULATE EMISSIONS FOR MAJOR ROADWAYS IN THE PHOENIX AIRSHED Final Report 495.

Balling, R.C. 1988. The climatic impact of a Sonor an vegetation discontinuity. Climatic Change. 13(1): 99-109.

Engineering-Science. 1987. PM 10 Emissions Inventory Data for the Douglas Planning Area. EPA

Contract No. 68-02-3888.

“Mexico National Emissions Inventory, 1999: Si x Northern States”, Final, April 30, 2004, prepared by Eastern Research Group (ERG), Acosta Y Asociados, and Transengineering, for the

Secretariat of the Environment and Natural Res ources and the National Institute of Ecology of Mexico, the United States Environmental Protection Agency, the Western Governors’Association, and the North American Commission for Environmental Cooperation. (1999 Mexico NEI).

National Resource Conservation Service (NRCS), USDA. http://www.wcc.nrcs.usda.gov/nwcc/site?sitenum=2026&state=az . Site # 2026.

U.S. Department of Transportation, 2011. Summ ary of Travel Trends: 2009 National Household Travel Survey. http://nhts.ornl.gov/2009/pub/stt.pdf.

U.S. EPA., 1995. Compilation of air pollutant emission factors, Volume 1. AP 42, Fifth Edition, http://www.epa.gov/ttn/chief/ap42/index.html#toc.

U.S. EPA., 2009. Motor Vehicle Emission Simulator (MOVES) 2010 User Guide. EPA-420-B09-041. http://www.epa.gov/otaq/models/moves/420b09041.pdf.

USGS. Binational Digital Soils Map of the Am bos Nogales Watershed, Southern Arizona and Northern Sonora, Mexico. Open-File Report 2004-1335.Appendix E.1

Vehicle Miles Traveled Calculation

This appendix includes information used to cal culate the emission reductions from double chipsealing in the technical support document (TSD). ADEQ estimated the number of vehicle miles travelled (VMT) for roads in the Rio Rico portion of the Nogales NA with data provided by the following sources:

 double chip-sealed road lengths provided by Santa Cruz County

 the number of dwellings travelin g on applicable paved roads was verified with aerial imagery

 the average number of trips per household pe r year was based on household income data

for Rio Rico obtained from the 2010 U.S. CensusThis page is intentionally blank.

### 13 Appendix E .1: VMT Calculation

Table A.1: This table pres ents individual ro adway length, the number of houses observed on the roadway, and the average number of trips take n per household for the Rio Rico area of the Nogales NA . VMT is calculated by the product of th ese values multiplied by an adjustment ratio of 0.5 (average distance of each roadway trave lled by residents) and divided by 5280 (conversion from feet to miles).

Roadway Length (L) [ft] Houses (H) Trips/household (T) VMT

Paseo Guebabi 14278 63 1981 168746

Paseo Mexico 21298 49 1981 195774 Calle Coyote 9008 38 1981 64217

River Rd 54910 31 1981 319323

Calle Arikara 5761 21 1981 22694

Circulo Tumbleweed 4442 15 1981 12500

Via Aloe Vera 4682 14 1981 12296

Camino Estrella 4891 13 1981 11928 Calle Cumpas 3587 11 1981 7402

Ceiba Ct 541 9 1981 913

Tala Ct 893 9 1981 1508

Ameca Ct 2817 8 1981 4228

Circulo Montana 24939 8 1981 37428

Circulo Mendez 1434 7 1981 1883

Annette Ct 1113 7 1981 1461 Gigi Ct 299 6 1981 336 Via Tecoripa 2115 6 1981 2380

Camino Estrella 4891 6 1981 5505 Campo Rd 1459 6 1981 1642

Padilla Ln 1128 6 1981 1270

Calle Ranuculo 2545 5 1981 2387

Cocula Ct 838 5 1981 786

Colmenar Ct 460 5 1981 432

Grillo Ct 475 5 1981 445

Batuc Ct 1131 5 1981 1061

Paseo Matamoros 7740 5 1981 7260 Calle Tepache 1089 5 1981 1021 Tuly Ct 264 5 1981 248

Corralitos Ln 906 5 1981 849

Via Dedal 1035 4 1981 776 Guaymas Ct 1360 4 1981 1021

Moneda Ct 212 4 1981 159

Lisboa Ct 820 4 1981 615

Cobra Ct 680 4 1981 510 Estoque Ct 818 4 1981 614 Forja Ct 532 4 1981 399

Camino Brizza Bonell 10183 4 1981 7641 Calle Cumpas 3587 4 1981 2692

Bacanora Ct 984 3 1981 554

Calle Remedios 6110 3 1981 3438

Corinto Ct 4176 3 1981 2350

### 14 Roadway Length (L) [ft] Houses (H) Trips/household (T) VMT

Llama Ct 408 3 1981 230

Via Italia 1042 3 1981 586 Arizpe Ct 259 3 1981 146

Meteoro Ct 228 3 1981 128

Cohete Ct 201 3 1981 113

Via Rita 1130 3 1981 636 Managua Ct 1893 3 1981 1065

Paseo Montura 2048 3 1981 1152 Fuego Ct 231 3 1981 130

Toltec Ct 284 2 1981 106

Beso Ct 212 2 1981 79

Boar Ln 391 2 1981 147 Copa Ct 356 2 1981 134

Suma Ct 101 2 1981 38

Uni Ln 261 2 1981 98

Soltar Ct 335 2 1981 126

Camino Loma 630 2 1981 236

Dosel Ct 580 2 1981 218

Toto Ct 202 2 1981 76

Adelita Ct 2271 2 1981 852 Payaso Ct 637 2 1981 239 Paseo Molango 4056 2 1981 1522 Trinity Ct 1458 2 1981 547

Hazel Ln 646 2 1981 242 Sunny Ln 685 2 1981 257 Via Papantla 2738 2 1981 1027

Via Pantera 2341 2 1981 878 Comoro Canyon Ln 2668 2 1981 1001

Kachina Dr 5498 2 1981 2063

Calle Coco 7706 2 1981 2891 Nikos Way 1846 2 1981 692 Via Fray Marcos 3932 1 1981 738

Calle Jamaica 4895 1 1981 918

Abanico Ct 451 1 1981 85

Inca Ct 349 1 1981 65 Avenida Reynosa 1624 1 1981 305

Calle Mora 2735 1 1981 513

Lost Ct 71 1 1981 13

Tata Ct 339 1 1981 64

Nutria Ct 635 1 1981 119

Silo Ln 306 1 1981 57 Song Dog Ct 171 1 1981 32

Johnson Ct 363 1 1981 68

Kite Ln 303 1 1981 57

Oro Ct 340 1 1981 64

Cuello Ct 298 1 1981 56

Dedo Ct 346 1 1981 65

### 15 Roadway Length (L) [ft] Houses (H) Trips/household (T) VMT

Donna Ct 350 1 1981 66

Ures Ct 557 1 1981 105

Zeus Ln 366 1 1981 69 Avenida Talanga 2515 1 1981 472

Jar Ct 77 1 1981 14

Tizimin Ct 2376 1 1981 446

Misa Ct 264 1 1981 49

Dandelion Ln 753 1 1981 141

Heno Ct 580 1 1981 109 Laguna Ct 403 1 1981 76

Mano Ct 286 1 1981 54

Purisima Ct 930 1 1981 174

Mia Ct 173 1 1981 33

Globo Ct 224 1 1981 42 Spices Ln 175 1 1981 33 Avenida Reynosa 1624 1 1981 305 Managua Ct 1893 1 1981 355

Paseo Matamoros 7740 1 1981 1452

Paseo Sombrilla 1666 1 1981 313

Mt Benedict Dr 1544 1 1981 290 Compostela Ct 724 1 1981 136 Gunsight Rd 4470 1 1981 838

Camino Vista Sonora 9721 1 1981 1824

Calle Jamaica 4895 1 1981 918 Duquesne Rd 160673 1 1981 30141

Amura Ln 2329 1 1981 437

Tree Ln 675 0 1981 0

Bola Ct 281 0 1981 0

Cacao Ct 398 0 1981 0

Belice Ct 256 0 1981 0

Cha Ct 173 0 1981 0

Adios Ct 256 0 1981 0

Paseo Sombrilla 1666 0 1981 0

Rum Ln 301 0 1981 0

Sahuarita Ct 1941 0 1981 0

Sana Ct 364 0 1981 0

Toluca Ct 1310 0 1981 0 Zaragoza Ct 1669 0 1981 0

Sodio Ct 259 0 1981 0

Acuna Ct 1363 0 1981 0

Del Ct 84 0 1981 0

Mescal Ct 820 0 1981 0 Compostela Ct 724 0 1981 0

Lazo Ct 366 0 1981 0

Leek Ct 137 0 1981 0

Luz Ct 325 0 1981 0

Maidu Ct 662 0 1981 0

### 16 Roadway Length (L) [ft] Houses (H) Trips/household (T) VMT

Marcarla Ct 1091 0 1981 0

Odisea Ct 594 0 1981 0

Salama Ct 1974 0 1981 0

Sauzal Ct 916 0 1981 0

Yard Ln 380 0 1981 0

Yuma Ct 110 0 1981 0

Calle Barril 2967 0 1981 0 Calle Granja 631 0 1981 0

Camino Cumbre 5343 0 1981 0

Camino Real 6824 0 1981 0

Fino Ct 1652 0 1981 0

Roble Ct 578 0 1981 0

Rosas Ct 450 0 1981 0

Calle Torreon 2888 0 1981 0

Nina Ct 228 0 1981 0

Circulo Huacana 2332 0 1981 0

Codo Ct 367 0 1981 0

Cola Ct 251 0 1981 0

Cono Ct 220 0 1981 0

Dividir Ct 2570 0 1981 0 Rey Ct 187 0 1981 0

Stable Ln 1072 0 1981 0

Tiarra Ct 230 0 1981 0

Calle Chivato 1171 0 1981 0

Cara Ct 312 0 1981 0

Hebilla Ct 921 0 1981 0 Kay Ct 1171 0 1981 0

Loreto Ct 723 0 1981 0

Tambor Ct 435 0 1981 0

Trono Ct 860 0 1981 0 Vereda Guadalajara 3286 0 1981 0

Paseo Montura 2048 0 1981 0

Tizimin Ct 2376 0 1981 0

Paseo Matamoros 7740 0 1981 0

Calle Cenote 990 0 1981 0

Stable Ln 1072 0 1981 0

Sonoita Creek Ranch Rd 15849 0 1981 0 Guajolote Ct 749 0 1981 0 Stoddard Way 5333 0 1981 0 Poppy Ct 4176 0 1981 0 Bodega Dr 1580 0 1981 0

Calle Barril 2967 0 1981 0

Calle Mandarina 6170 0 1981 0

Placita Verdura 907 0 1981 0

Garra Ct 350 0 1981 0

Wild Rose Ct 834 0 1981 0

Victorio Dr 3477 0 1981 0

### 17 Roadway Length (L) [ft] Houses (H) Trips/household (T) VMT

Pendleton Dr 76784 0 1981 0

Corinto Ct 4176 0 1981 0

Camino Real 6824 0 1981 0

Trono Ct 860 0 1981 0 Zaragoza Ct 1669 0 1981 0

Camino Las Barrancas 3102 0 1981 0

Camino Real 6824 0 1981 0

Calle Torreon 2888 0 1981 0

Paseo Riachuelo 6524 0 1981 0

Paseo Riachuelo 6524 0 1981 0 Circ Vista Del Lago 5022 0 1981 0 Circ Vista Del Lago 5022 0 1981 0

Cuates Buttes Ln 4020 0 1981 0 Del Rey David Blvd 5986 0 1981 0

Bravo Ln 1379 0 1981 0

Total VMT 968460

Total PM 10 (ELow) 105

Total PM 10 (EHigh) 273This page is intentionally blank.

### Appendix E.2 Road Paving/Chip-Sealing Documentation Provided by Santa Cruz County for the Nogales NA

The documents in this appendix were provi ded by Santa Cruz County. County officials highlighted roads that had been double ch ip-sealed in the Rio Rico community from 2002-2008. ADEQ determined four roads totaling 8.6 miles were within the Nogales NA.

This information was then used for the calcu lations in the technical support document.

### This page is intentionally blank.This page is intentionally blank.Appendix E.3 ADEQ Map Displaying Paved and Unpaved Roads in the Rio Rico Section of the Nogales NA

This appendix contains a map developed by ADE Q using geographic information system (GIS) data to show which roads in the Nogales NA, excluding the City of Nogales, were paved and unpaved. ADEQ determined 134.4 miles of road were paved and 53.5 we re unpaved in this section of the Nogales NA.This page is intentionally blank.This page is intentionally blank.Appendix E.4 Satellite Imagery used to Verify Road P aving/Double Chip-Sealing in the Nogales NA

This appendix contains before a nd after satellite imagery for each paved road cited in the TSD. The black and white 1992 images are blurry, typical of satellite imagery from that era, and somewhat difficult to discern. Some roads identified for paving in the 1993 Nogales NA SIP appear to have been paved when the 1992 sate llite image was taken, likely due the development process for the 1993 Nogales NA SIP taking several years to complete. Satellite imagery is unavailable for years prior to 1992.

### This page is intentionally blank.Figure 1: Aerial photography of Calle Arikara road in Rio Rico from 1992 (left)and 2010 (right) confirming chip-seal paving of theroadway occurred between these dates.Figure 2: Aerial photography of Paseo Mexico road in Rio Rico from 1992 (top) and 2010 (bottom) confirming chip-seal paving ofthe roadway occurred between these dates.

### Figure 3: Aerial photography of Calle Coyote road in Rio Rico from 1992 (left) and 2010 (right) confirming chip-seal paving of the roadway occurred between these dates.Figure 4: Aerial photography of Annette Ct. in Rio Rico from 1992 (left) and 2010 (right) confirming chip-seal paving of the roadwayoccurred between these dates.

### Figure 5: Aerial photography of Paseo Guebab i road in Rio Rico from 1992 (top) and 2010 (bottom) confirming chip-seal paving of th e roadway occurred between these dates.

### Figure 6: Aerial photography of Royal Ro ad in Nogales from 1992 (left) and 2010 (right) confirming chip-seal paving of the roadway occurred between these dates.

### Figure 7: Aerial photography of Hohokam Ro ad in Nogales from 1992 (left) and 2010 (right) confirming chip-seal paving of the roadway occurred between these dates.Figure 8: Aerial photography of La QuintaRoad in Nogales from 1992 (top) and 2010 (bottom) confirming chip-seal paving of theroadway occurred between these dates.

### Figure 9: Aerial photography of Yucca Dr. in Nogales from 1992 (top) and 2010 (bottom) confirming chip-seal paving of the roadway occurred between these dates.Figure 10: Aerial photography of BristolDr. in Nogales from 1992 (top) and 2010 (bottom) confirming chip-seal paving of theroadway occurred between these dates.

### Figure 11: Aerial photography of Target Range Rd. in N ogales from 1992 (top) and 2010 (bottom) confirming chip-seal paving of the roadway occurred between these dates. 

### Figure 12: Aerial photogra phy of Frank Reed Rd. in N ogales from 1992 (top) and 2010 (bottom) confirming chip-seal paving of the roadway occurred between these dates.Figure 13: Aerial photographyof Kino Rd. in Nogales from 1992 (top) and 2010(bottom) confirming chip-seal paving of theroadway occurred between these dates.

### Figure 14: Aerial photography of Kelsey Ave. in Nogales from 1992 (top) and 2010 (bottom) confirming chip-seal paving of the roadway occurred between these dates.Figure 15: Aerial photography ofW 1st Ave. in Nogales from 1992 (top) and 2010(bottom) confirming chip-seal paving of theroadway occurred between these dates.Figure 16: Aerial photography of Vista del Cielo - the main collector shown in the photographs below - in Nogales from 1992 (top) and 2012 (B ing Maps) confirming paving of the roadway

occurred between these dates.

### Appendix F Correspondence

### This page is intentionally blank.

### Appendix F.1 Letter from EPA Approving Arizona's Air Monitoring Network Plan for 2011

### This page is intentionally blank.

### Appendix F.2 Email from Santa Cruz County Confirming Road Maintenance Procedures and Equipment

### This page is intentionally blank.

### James Wagner

From: Carlos Rivera [crivera@co.santa-cruz.az.us]

Sent: Monday, April 02, 2012 5:39 PM

To: James Wagner

Subject: FW: Nogales PM10 Nonattainment Area

Attachments: PM10 Non attainment area map.pdf 

### Pa g e 1 of 1

4/6/2012 Mr. Wagner,

Attached and below is the response from our Public Works Director. If you should require any additional

information please do not hesitate to contact me.

Carlos

From: Jesus J. Valdez

Sent: Monday, April 02, 2012 4:09 PM

To: Carlos Rivera Subject: RE: Nogales PM10 No nattainment Area

Carlos,

Attached is a map of the nonattainment area. The County has a total of 240 miles of roads: 40 miles of

dirt roads & 200 miles of paved/double chip roads.

In addition, the County has implemented an on

‐ call program that has PW employees on standby after
regular working hours to respond to road emergencies and/or road blockage. PW crews also do clean up
after every storm event by removing debris and sweeping the road. The PW department currently has

two sweepers in the heavy equipment fleet.

J esus Valdez, P.E.

Interim Public Works Director
County Engineer

Santa Cruz County

Ph. 520

‐ 375

‐ 7830

Fax. 520

‐ 375

‐ 7846Appendix F.3 Email from City of Nogales Confirming Road Paving, Road

Maintenance Procedures and Equipment

### This page is intentionally blank.From: Juan Guerra [mailto: jguerra@nogalesaz.gov]

Sent: Wednesday, April 11, 2012 3:24 PM

To: James Wagner

Cc: edelgado@nogalesaz.gov; abarcenas@nogalesaz.gov Subject: Re: Nogales Street Sweepers

We are working on it to get the total length of paved roads. Although all public roads are paved some of

them require significant improvements.

As you may be aware, there are some private roads and commercial properties not paved.

From : James Wagner [mailto: Wagner.James@azdeq.gov ]

Sent : Wednesday, April 11, 2012 12:19 PM

To : Juan Guerra < jguerra@nogalesaz.gov > Subject : FW: Nogales Street Sweepers

Hello again, Juan.

EPA would like us to get data layers for paved/unpaved roads in Nogales so that we can claim emissions reductions for unpaved roads identified in the 1987 emissions inventory for the Nogales area. Can you help us with that request?

Thanks, 

### Jim Wagner

EHS II

602.771.2388

From: Juan Guerra [mailto: jguerra@nogalesaz.gov ]

Sent: Thursday, December 08, 2011 3:42 PM

To: James Wagner

Cc: Tony Santa Cruz Subject: RE: Nogales State Implementation Plan

Hi Jim:

Please see below the answers to your questions. Let me know if you have any more questions.

1. ‐ The City has two sweeper but only one is in operation (The other is broken).

2.

‐ The two street sweepers are standard.

3.

‐ The streets are cleaned from Monday

‐ Friday (No weekends and holydays)

4.

‐ The City does not block any private unpaved road.

Sincerely,

Juan Guerra, PE., CFM | City Engineer | City of Nogales, AZ | phone: 520

‐ 285

‐ 5753| fax: 520

‐ 287

‐ 8352 |

1450 N. Hohokam Drive, Nogales, AZ 85621 | jguerra@nogalesaz.gov

Office hours: Monday

– Friday, 8 a.m.

– 5 p.m.

E

‐ mails generated by council members, members of City commissions and committees or by staff and that pertain to City

business are public records. Therefore, the e

‐ mails must be preserved according to the City’s records retention schedule andgenerally be made available for public inspection. E

‐ mail correspondence is regularly reviewed by members of the public and

other interested parties, including media outlets and reporters. To ensure compliance with the Open Meeting Law, members of

the City Council, and of City commissions and committees should not forward e

‐ mail correspondence to other memb ers of the
Council, board or commission. Members of the Council and other public bodies may reply to this message, but should not copy
other members of the public body. Any questions should be directed to the City of Nogales' City Attorney: (520) 287

‐ 6571.

From: James Wagner [mailto: Wagner.James@azdeq.gov ]

Sent: Thursday, December 08, 2011 3:22 PM

To: Juan Guerra Subject: Nogales State Implementation Plan



### Hello Juan,

It was nice speaking with you earlier. We just need to know a few things for the update to the 1993 Nogales PM10 state implementation plan.

 

### How many street sweepers does the City own?

 

### Are they "PM10 certified" or standard sweepers?

 

### How often does the City clean the streets?

For those unpaved roads not accepted into the City's Street Maintenance Program, does the City try to block traffic, for example with boulders?

If you have any questions, please let me know.

Thanks,

Jim Wagner

ADEQ Air Quality Division

602.771.2388

NOTICE: This e-mail (and any attachments) may contain PRIV ILEGED OR CONFIDENTIAL information and is intended only for the use of the specific individual(s) to whom it is addressed. It may contain information that is privileged and confidential under state and federal law. This information may be used or disclosed only in accordance with law, and you may be subject to penalties under law for improper use or further disclosure of the information in this e-mail and its attachments. If you have received this e-mail in error, please immediately notify the person named above by reply e-mail, and then delete the original e-mail. Thank you.

NOTICE: This e-mail (and any attachments) may contain PRIV ILEGED OR CONFIDENTIAL information and is intended only for the use of the specific individual(s) to whom it is addressed. It may contain information that is privileged and confidential under state and federal law. This information may be used or disclosed only in accordance with law, and you may be subject to penalties under law for improper use or further disclosure of the information in this e-mail and its attachments. If you have received this e-mail in error, please immediately notify the person named above by reply e-mail, and then delete the original e-mail. Thank you.Appendix F.4 Completeness Letter from EPA for the 1993 Nogales PM 10 Nonattainment Area State Implementation PlanThis page is intentionally blank.UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX

75 Hawtharne Street

San Francisco, Ca. 94105

November 30, 1993


### Edward 

### Z. Fox

Director Arizona Department of Environmental

- 

### Quality

3033 North Central Avenue Phoenix, Arizona 85012

Dear Mr. Fox:

On June 14,1993, you submitted a revision to the Arizona State Implementation Plan

for achieving and maintaining the National Ambient Air Quality Standards for particulate

matter 10 microns or less in aerodynamic diameter (PM10) in the Nogales nonattainment

area.

We have revikwed this package for completeness and found that it conforms to the completeness criteria in 40 CFR Part 5 1, Appendix V. The complete submittal addresses

the finding of nonsubmittal made by EPA on December 16, 1991, and thus stops the clock

for mandatory sanctions under section 179(a) of the Clean Air Act.

The SIP revision found to be complete is now in the process of being reviewed. Once reviewed, we will prepare a rulemaking notice for submittal to our Headquarters

office for publication in the Federal Register.

If you have any questions regarding our review, please call me or have your staff call

Wallace Woo, Chief of the Plans Development Section in the Air Planning Branch at (4 15)744- 1207.

Sincerely,

David P. Howekamp

Director

Air & 

### Toxics Division

cc: Nancy Wrona, Arizona Department

of Environmental Quality

Printed on Recycled PaperThis page is intentionally blank.Appendix F.5 Santa Cruz County Email Regarding Paved Roads in Rio RicoThis page is intentionally blank.From: Jesus J. Valdez [mailto:jjvaldez@co.santa-cruz.az.us]

Sent: Thursday, March 03, 2011 5:57 PM

To: Roxanne J. Linsley Subject: FW: highlighted roads!

Attached is a pdf of the dirt roads that the County has chip seal since 2002, its roughly about 60 miles. From oral
history, staff informed me that an additional 40 miles of dirt roads were chip seal from 1993 to 2001. Also, I

research for a policy that the County had adopted regar ding clea n up afte r storm events, and was unsuccessful in finding one. Please give me a call if you have any questions.

Jesus Valdez, P.E.

Interim Public Works Director

County 

### Engineer

Santa Cruz 

### County

Ph. 520

‐ 375

‐ 7830

Fax. 520

‐ 375

‐ 7846

From: Norma Northcross

Sent: Thursday, March 03, 2011 5:44 PM

To: Jesus J. Valdez Subject: highlighted roads!

ThanksNORMA B. NORTHCROSS

Central Permits Coordinator

Right of Way Agent

Santa Cruz County

(520) 375-7869



### NOTICE: This e-mail (and any attachments) may contain PRIVILEGED OR CONFIDENTIAL information and is intended only for the use of th e specific individual(s) to whom it is addressed. It may contain information that is privileged a nd confidential under state and federal law. This information may be used or disclosed only in accordance with law, and you may be subject to penalties under law for improper use or further disc losure of the information in this e-mail and its attachments. If you have receiv ed this e-mail in error, plea se immediately notify the person named above by reply e-mail, and then delete the original e-mail. Thank you.

### 1 APPENDIX G

SUPPLEMENTARY INFORMATION

The information included in this appendix is considered supplementary and not included for

submittal with this SIP.

1. Require Dust Control Plans for Construction or Land Clearing Projects

Santa Cruz County Grading Ordinance 2001-06, adopted in 2001, was not included as a control measure in the 1993 Nogales SIP. The ordinance requires control measures for construction and land clearing projects. Permits are required for any grad ing activity exceeding 50 cubic yards. The grading ordinance requires dust control for all areas disturbed during grading or clearing of land. 1 The ordinance specifies that only land that will later be resurf aced, hydroseeded, landscaped, or developed may be disturbed. The ordinance further requires disturbed areas that are not landscaped or developed be hydroseeded. Officials are authorized to conduct site inspections to determine the adequacy of dust and erosion control methods and may require mitigation me asures. Dust and erosion control methods must be completed within (30) days of clear ing, unless waived by the County.

The City of Nogales Development Standards C ode does not provide specific mitigation measures for land clearing and construction activity. Ar ticle 8, Section 8-5-6, however, requires “land use to comply with State and federal regulations, and pr ohibits particulate emissions from creating public health concerns...No emission shall be permitted wh ich can cause damage to health, to animals, or vegetation, or other forms of property...” These provisions provide local agencies with authority to pursue air quality nuisances, including emissions re lated to construction or land clearing projects. 2

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

Paved Roads

Section 8-6-6 of the City of Nogales building code, Surface Drainage and Storm Sewer System, requires that building permits will only be issued after provisions to control storm water run-off, including culverts or inlets, have been implemen ted. These provisions prevent sediment from washing onto paved streets and creating vehicle trackout emissions . Section 8-6-6 also requires detention basins or other means of preventing significant water run-off where applicable. Section 8-16-23, Design Standards for On-Site Retention of Storm Water, requires on-s ite storm water retention for all developments one acre or larger unless the site is served by a storm sewer, channel, or natural drainage way approved by the City Engineer. 3

Santa Cruz County's Flood Control District estab lished standards for private driveway crossings to prevent erosion onto paved roads. 4

1 Santa Cruz County Grading Ordinance 2001-06. Pgs. 6-7. <http://www.co.santa-cruz.az.us /com_development/building/pdf/GradingOrdinanceRevised.pdf >

2 City of Nogales, Arizona, Development Standards Code, Article 8. Pgs. 66-67. <https://imageserv5.team-logic.com/mediaLibrary/78/Article_008.pdf >

3 Ibid. Pg. 167.

4 Santa Cruz Flood Control District. “Driveway Crossing Standards.” <http://www.co.santa-cruz.az.us /public_works/flood/pdf/DrivewayCrossingStandard.pdf >

### 2 3. Require Curbing and Pave or Stabilize Paved Road Shoulders

Section 8-8-2 of the Nogales City code requires that all “streets shall have Portland Cement Concrete curbs and gutters along the pavement edge constructed to city minimum standards for

construction...All streets shall have Portland Cement Concrete sidewalks behind the curb-gutter where curb-gutter is required.” 5

Section 1504.5, effective October 5, 1973, of the County Zoning and Development Code states

that “...curbs and gutters shall be required in all Zoni ng Districts except GR (General Rural) and SR (Suburban Ranch) unless a variance is granted by the Planning Commission...” 6 Curbing streets and stabilizing road shoulders in the sparsely populated rural districts of Rio Rico is not currently economically feasible.

4. Pave, Vegetate, or Chemically Stabilize Unpaved Parking Areas

Section 8-9-5 of the Nogales Development Standards Code, General Parking Lot Design Requirements, requires that “A. Surfacing and Drainage: Every commercial parking lot, including display areas for vehicle parking, s hall be paved with two (2) inches of asphaltic concrete over four (4)

inches of aggregate base course or four (4) inches of Portland Cement Concrete reinforced with #8 six (6) inch by six (6) inch wire mesh over a sub-ba se compacted to ninety-five percent (95%) density and properly drained with a minimum grade of 0.5% and a maximum grade of six percent (6%). Every commercial parking lot shall be subject to approv al by the Site Plan process of Section 8-18.” 7 The code also requires the owner or occupant of a building with a paved parking area to maintain the surface, lighting, and landscaping or face a violation.

As required by the 1993 NNA SIP, the County pave d the Sheriff’s station parking lot. In 2005, the County amended Article 11 of the County Zoning and Development Code to require paved parking lots and entrances for commercial buildings and multifamily residences. 8

5. Pave, Vegetate, or Chemically Stabilize Unpaved Parking Areas

Section 8-9-5 of the Nogales Development Standards Code, General Parking Lot Design Requirements, requires that “A. Surfacing and Drainage: Every commercial parking lot, including display areas for vehicle parking, s hall be paved with two (2) inches of asphaltic concrete over four (4)

inches of aggregate base course or four (4) inches of Portland Cement Concrete reinforced with #8 six (6) inch by six (6) inch wire mesh over a sub-ba se compacted to ninety-five percent (95%) density and properly drained with a minimum grade of 0.5% and a maximum grade of six percent (6%). Every commercial parking lot shall be subject to approv al by the Site Plan process of Section 8-18.” 9 The code

5 City of Nogales, Arizona, Development and Standards Code, Article 8. Pg. 89. <https://imageserv5.team-logic.com/mediaLibrary/78/Article_008.pdf >

6 Santa Cruz County Zoning and Development Code 2011. Pgs. 146-148. <http://www.co.santa-cruz.az. us/com_development/pdf/ZoningandDevelopmentCode.pdf >

7 City of Nogales, Arizona, Development and Standards Code, Article 8. Pgs. 127-134. <https://imageserv5.team-logic.com/mediaLibrary/78/Article_008.pdf >

8 Santa Cruz County Zoning and Development Code 2011. Pg. 112. <http://www.co.santa-cruz.az. us/com_development/pdf/ZoningandDevelopmentCode.pdf>

9 City of Nogales, Arizona, Development and Standards Code, Article 8. Pgs. 127-134. <https://imageserv5.team-logic.com/mediaLibrary/78/Article_008.pdf >

### 3 also requires the owner or occupant of a building with a paved parking area to maintain the surface, lighting, and landscaping or face a violation. As required by the 1993 NNA SIP, the County pave d the Sheriff’s station parking lot. In 2005, the County amended Article 11 of the County Zoning and Development Code to require paved parking lots and entrances for commercial buildings and multifamily residences. 10

6. Require Revegetation, Chemical Stabilizat ion, or other Abatement of Wind

Erodible Soil

The City of Nogales Development Standards C ode does not provide specific mitigation measures for revegetation or stabilization of unstabilized soil; however, Article 8, Section 8-5-6 requires “land use to comply with State and federal regulations, and pr ohibits particulate emissions from creating public health concerns...No emission shall be permitted wh ich can cause damage to health, to animals, or vegetation, or other forms of property...” These provisions give local authorities power to pursue air quality nuisances, including emissions relate d to construction or land clearing projects. 11

Santa Cruz County Ordinance 2001-06, Excavation and Grading, Section 3316-Erosion Control, requires that “Dust and erosion control shall be required for all areas disturbed during grading, clearing, or brushing of land whether it requires a grading perm it or not. Only areas which will later be resurfaced, hydroseeded, landscaped, or built on may be disturbed. All disturbed areas which are not resurfaced, landscaped, or built on shall be hydroseed ed with plant species appropriate to the site and its surrounding native habitat...The Building Official may make site inspections to determine the adequacy of dust and erosion control methods and may require modifie d mitigation measures, such as, but not limited to, paving, rip-rap, and, or, erosion control blankets. Dust and erosion methods shall be completed within (30) days of clearing, unless waived by the Building Official.” 12



### 7. Road Paving in Nogales, Sonora, Mexico

The North American Development Bank (NADB) h as funded road paving projects in Nogales, Sonora. A study of the city conducted from 2004- 2007 determined that 65 percent of the city was unpaved, with 35 percent having some type of hard surface. According to the NADB, as of 2010, 865 roads are surfaced. However, 1,065 roads extending 133 miles remained unpaved as of August 2010. In July 2004, the NADB announced 17 million U.S. in funding for street improvements. 13 In 2007, the NADB announced 9 million U.S. dollar funding for street improvements. 14 As of September 2011, the city was accepting bids on an additional 10 miles of road surfacing. 15 More paving projects are planned

for the immediate future.

10 Santa Cruz County Zoning and Development Code 2011. Pg. 112. <http://www.co.santa-cruz.az. us/com_development/pdf/ZoningandDevelopmentCode.pdf>

11 City of Nogales, Arizona, Development Standards Code, Article 8. Pgs. 66-67. <https://imageserv5.team-logic.com/mediaLibrary/78/Article_008.pdf >

12 Santa Cruz County Grading and Excavating Ordinance. Pgs. 6-7

. < http://www.co.santa-cruz.az.us/com_developmen t/building/pdf/GradingOrdinanceRevised.pdf >

13 North American Development Bank press release. July 2004. <http://www.nadb.org/pdfs/state_project s/FS%20Nogales%20SON%20AQ%20Eng.pdf >

14 North American Development Bank press release. January, 2007. <http://www.nadb.org/Reports1/Press _Releases/english/2007/013007.htm >

15This page is intentionally blank.Appendix H

NNA Monitoring Data 2008-2010This page is intentionally blank.Appendix H Nogales Continuously Operating BAM Monitor Air Quality Data 2008-2010

Year # of

Observations % of

Observations Max 24-hour

Concentration ( μ g/m 3 ) 2 nd Highest

Concentration ( μ g/m 3 ) # of

Estimated

Exceedances

2008 355 97 234 217 13.2

2009 343 94 238 204 2.0

2010 126 35* 191 177 8.5 3-Year Average Estimated Number of Exceedances 7.9
*2010 data does not meet completeness criteria. Appendix H Nogales Partisol Filter-Based Monitor Air Quality Data 2008-2010

Year Quarter # of

Observations % Data Completeness Max 24-hour

Concentration ( μ g/m 3 ) 2 nd Highest

Concentration ( μ g/m 3 ) # of

Estimated

Exceedances

2008 1 15 88 108.7 99.7

2 15 100 147.2 86.7

3 15 100 44 41.3

4 14 93 155.3 150.3

Annual 58 95 155.3 150.3 6.6

2009 1 13 87 116.4 105.5

2 16 100 57.9 51.8

3 14 93 72.8 67.1

4 15 100 123.8 109.7

Annual 58 95 123.8 116.4 0

2010 1 15 100 96.8 84.7

2 14 93 57.2 45.5

3 15 94 63.3 55.9

4 13 87 74.5 66.5

Annual 57 93 96.8 84.7 0 3-Year Average Estimated Number of Exceedances 2.2UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

DESIGN VALUE REPORT

Dec. 23, 2011 Report Request ID: 941451 Report Code: AMP480

Selection Criteria Page 1 User ID: BNE

State County City

Site Parameter POC AQCR UAR CBSA CSA EPA

Region Method Duration Begin Date End Date

04 023 0004 GEOGRAPHIC SELECTIONS

PROTOCOL SELECTIONS

Parameter

Classification Parameter Method Duration

81102

SELECTED OPTIONS

USER SITE METADATA

MERGE PDF FILES

QUARTERLY DATA IN WORKFILE

WORKFILE DELIMITER

SINGLE EVENT PROCESSING Option Type Option Value

STREET ADDRESS

YES

NO

,

EXCLUDE REGIONALLY CONCURRED EVENTS

GLOBAL DATES

2010 Start Date End Date

2010 Tribal

Code

APPLICABLE STANDARDS

Standard Description

PM10 24-hour 2006UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

AIR QUALITY SYSTEM

PRELIMINARY DESIGN VALUE REPORT Report Date: Dec. 23, 2011

Notes: 1. Warning: Computed design values are a snapshot of the data at the time the report was run (may not be all data for year).

2. Annual Values not meeting completeness criteria are marked with an asterisk ('*'). Page 1 of 2UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

AIR QUALITY SYSTEM

PRELIMINARY DESIGN VALUE REPORT Report Date: Dec. 23, 2011

Notes: 1. Warning: Computed design values are a snapshot of the data at the time the report was run (may not be all data for year).

2. Annual Values not meeting completeness criteria are marked with an asterisk ('*'). Page 2 of 2 

### Pollutant:

Standard Units:
NAAQS Standard:

Statistic: PM10 Total 0-10um STP(81102) Design Value Year: 2010

Micrograms/cubic meter (25 C)(001)

PM10 24-hour 2006 Annual Estimated Days > Standard REPORT EXCLUDES MEASUREMENTS WITH REGIONALLY CONCURRED EVENT FLAGS.

Level: 150 State Name: Arizona

Site ID POC STREET ADDRESS |

|

| Estimated #Complete

Cert. |

|

| Estimated #Complete

Cert. |

|

| Estimated Quarter Cert. |

|

| Estimated

Exceedances Validity

Ind. 2010 2009 2008

04-023-0004

04-023-0004 1

3 300 N MORLEY AVE

300 N MORLEY AVE 0

8.5 4

0 0

2 4

4 6.6

13.2 4

4 2.2

7.9 Y

Y * Count Quarter Exceedances

0

6 Quarter Count Exceedances

0

2 Count #Complete Exceedances

1

13 3 - YearAppendix I

Quantitative Milestone and Reasonable Further Progress Report for the Nogales PM 10 Nonattainment AreaThis page is intentionally blank.This page is intentionally blank.Appendix K

Public Process Documentation

This appendix contains the public process docum ents for the first and second public comment periods for the 2012 Nogales PM 10 SIP:

 Public Hearing Notice

 Affidavit of Publication for Notice of Public Hearing

 Hearing Agenda

 Hearing Sign-in Sheet

 Hearing Transcript

 Public Comments

 Responsiveness Summary

 Public Hearing OfferThis page is intentionally blank.

### ARIZONA DEPARTMENT OF ENVIRONMENTAL QUALITY

30 DAY PUBLIC COMMENT PERIOD AND HEARING ON

NOGALES MODERATE PM 10 

### MAINTENANCE PLAN

The Arizona Department of Environmental Qu ality (ADEQ) is beginning a thirty day public comment period with the publica tion of this notice on May 18, 2012, for the proposed Nogales Moderate Area PM 10 

### State Implementation Plan (SIP). The proposed SIP is an update of the plan submitted by ADEQ to the U.S. Environmental Protection Agency (EPA) for the Nogales Nonattainment Area (NNA) in 1993.

A public hearing on the proposed SIP revision to be submitted to the U.S. Environmental Protection Agency the will be held on T hursday, June 21, 2012, at 2:00 p.m. at the Nogales Chamber of Commerce, 123 West Kino Park Place, Nogales, AZ 85621. All interested parties will be given an opportuni ty at the public heari ng to submit relevant comments, data, and views, orally and in writing. Written comments may be submitted prior to or during the public hearing and must be postmar ked or received by at ADEQ by 5:00 p.m. on June 21, 2012.

All written comments should be a ddressed, faxed, or e-mailed to:

Jim Wagner Arizona Department of Environmen tal Quality - Air Quality Division 1110 West Washington Street, Phoenix, AZ 85007 FAX: (602) 771-2366

E-Mail: JW3@azdeq.gov

Copies of the PM 10 

### SIP proposal are available for revi ew online at the following web

address http://www.azdeq.gov/cgi-bin/vertical.pl and in hard copy at the following

locations:

ADEQ Records Center First Floor, 1110 W. Washington Street Phoenix, Arizona 85007 Attention: Norlene Lara, (602) 771-4712

Nogales Library

777 E. Grand Avenue Nogales, AZ 85621 Attention: Suzanne Haddock, ( 520) 287- 6571This page is intentionally blank.This page is intentionally blank.This page is intentionally blank.This page is intentionally blank.

### 1 PROPOSED ARIZONA AIR QUALITY 1



### STATE IMPLEMENTATION PLAN (SIP) 2



### for the 3



### Nogales PM-10 Nonattainment Area 4

5



### Oral Proceeding 6



### Hearing Officer Script 7



### 2:00 PM, June 21, 2012 8

9



### Bruce Friedl: Good afternoon and thank you for coming. I now open this hearing on a proposed 10



### revision to the Arizona State Implementati on Plan for the 2012 Nogales PM-10 State 11



### Implementation Plan for the Noga les PM-10 Nonattainment Area. 12

13



### It is June 21, 2012, and the time is 2:24 PM. The lo cation is the Nogale s-Santa Cruz County 14



### Chamber of Commerce, 123 West Ki no Park Place, Nogales, AZ. My name is Bruce Friedl, and 15



### I have been appointed by the Di rector of the Arizona Departme nt of Environmental Quality 16



### (ADEQ) to preside at this proceeding. 17

18



### The purposes of this proceeding are to provide the public an opportunity to: 19



### (1) hear about the substance of th e proposed air quality plan revision, 20



### (2) ask questions regarding the revision, and 21



### (3) present oral argument, data and views regarding the revision in the form of comments on the 22



### record. 23

24



### Representing the Department is Diane Arnst. 25

26



### Public notice appeared in the Noga les International on May 18 and 21, 2012, and on ADEQ’s 27



### website. The documents subject to co mment were made available online at www.azdeq.gov and 28



### in hard copy at the ADEQ Phoenix office and at the Nogales-Rochlin Public Library at 518 N. 29



### Grand Ave. Nogales, AZ. 30

### 2 The procedure for making a public comment on the record is straightforward. If you wish to 1



### comment, you need to fill out a speake r slip, which is available at the sign-in table, and give it to 2



### me. Using speaker slips allows everyone an opport unity to be heard and allows us to match the 3



### name on the official record with the comments . You may also submit written comments to me 4



### today. Please note, the comment period for th e proposed SIP revision ends today, June 21, 2012 5



### at 5:00 PM. All comments must be postmarke d or received at ADEQ by 5:00 PM today, June 6



### 21, 2012 whether sent via U.S. mail or via e-mail or via FAX. Written comments can be mailed 7



### to Jim Wagner, Air Quality Planning Section, Ar izona Department of Environmental Quality, 8



### 1110 W. Washington Street, Phoenix, Arizona 85007 or jw3@azdeq.gov. Comments may also 9



### be faxed to (602) 771-2366. 10

11



### Comments made during the formal comment period are required by law to be considered by the 12



### Department when preparing the final state im plementation plan. Th is is done through the 13



### preparation of a responsiveness summary in which the Department responds in writing to written 14



### and oral comments made during the formal comment period. 15

16



### First, we will present a brief overview of the proposed revision to the state implementation plan. 17

18



### Secondly, I will conduct a question and answer pe riod. The purpose of the question and answer 19



### period is to provide information that ma y help you in making comments on the proposed 20



### revision. 21

22



### Thirdly, I will conduct the oral comment period. At that time, I will begin to call speakers in the 23



### order that I have received speaker slips. 24

25



### Please be aware that any comments at today's hear ing that you want the Department to formally 26



### consider must be given either in writing by th e deadline or on the record at today’s hearing 27



### during the oral comment period of this proceeding. 28

29



### At this time, Diane Arnst will give a brief overview of the proposal. 30



### * * * * * 31

### 3 The Nogales area was designated as a "mo derate" nonattainment area for the 1987 1



### 24-hour PM-10 National Ambient Air Quality Standards (NAAQS) by operation of law 2



### upon enactment of the 1990 amendments to the Clean Air Act (CAA). The planning 3



### area includes all of the City of Nogales, and portions of the Rio Rico Southwest and Rio 4



### Rico Southeast communities. 5

6



### As required by the 1990 ame ndments, Arizona submitted a State Implementation Plan 7



### for the Nogales PM-10 Nona ttainment area in November 1993. The Environmental 8



### Protection Agency (or EPA) found the plan to be complete, but did not take final action 9



### on it. The plan included control measures t hat brought the Nogales area into attainment 10



### of the PM-10 standard by the December 31 , 1994, deadline established by the 1990 11



### Clean Air Act amendments. EPA published a De termination of Attainment by 1994 in 12



### the Federal Register on J anuary 11, 2011. The Nogales area continued to meet the PM13



### 10 standard through 1998. The area has been in and out of attainment since then. 14

15



### The Proposed State Implement ation Plan for the Nogales Nonattainment Area will 16



### ultimately serve as a replacement for t he 1993 plan. Clean Air Act Section 179(B) 17



### provides that any area that es tablishes to the satisfaction of EPA that it would attain the 18



### PM-10 NAAQS “but for emissi ons emanating from outside t he United States” shall not 19



### be subject to certain Clean Air Act requi rements, including demonstrations of 20



### reasonable further progress in air quality, demonstrations of attainment, and 21



### contingency measures. The proposed plan includ es four technical demonstrations that 22



### Nogales, Arizona would be in attainment of the PM-10 standard "but for" emissions 23



### originating in Nogales Municipality, Sonora, Mexico. ADEQ worked closely with EPA 24



### Region IX to develop the Emissions Inventory of sources in Arizona and sources in 25



### Sonora contributing PM-10 emissions to this air quality planning ar ea and to develop the 26



### technical demonstrations. The most significant source cat egory in Nogales, Arizona is 27



### fugitive dust from unpaved roads. All pu blic roads in the City of Nogales have been 28



### paved and accepted into the City’ s Street maintenance Program . ADEQ estimates that 29



### 134.4 miles of unpaved roads in the Rio Rico portion of t he planning area have been 30



### double chip-sealed and approximat ely 53 miles of unpaved r oads remain. The proposed 31

### 4 plan also demonstrates that all other applicable requirement s of the Clean Air Act have 1



### been met. 2

3



### Mr. Friedl: Thank you, Diane. This concludes the explanation period of this proceeding on the 4



### proposed revision to the state implementation plan. 5

6



### * * * * * 7



### Mr. Friedl: Are there any que stions before we move to the oral comment period? 8



### QUESTIONS 9



### This concludes the question and answer peri od of this proceeding on the proposed state 10



### implementation plan revision. 11

12



### * * * * * 13



### Mr. Friedl: I now open this proceeding for or al comments. Does anybody wish to make a 14



### comment? 15



### COMMENTS 16



### Mr. Friedl: This concludes the oral comment period of this proceeding on the proposed state 17



### implementation plan revision. 18

19



### * * * * * 20



### If you have not already submitted written comments, you may submit them to me at this time. 21



### Again, the comment period for this proposed revision to the state implementation plan ends at 22



### 5:00 PM MST today, June 21, 2012. 23

24



### Thank you for attending. 25

26



### The time is now 2:33 PM. I now close this oral proceeding. 27UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX

75 Hawthorne Street

San Francisco. CA 94105·3901



### June 21, 2012

Mr. Eric Massey, Division Director

Air Quality Division

Arizona Department of Environmental Quality

1110 West Washington Street
Phoenix,Arizona 85007

Re: EPA comments on the Proposed State Implementation Plan (SIP) for the Nogales PM10

Nonattainment Area

Dear Mr. Massey:

On June 20, 2012, Regional Administrator Blumenfeld signed a Federal Register Notice proposing approval of Arizona's "Proposed State Implementation Plan for the Nogales PM10 Nonattainment

Area." As described in this notice, the U.S. Environmental Protection Agency's (EPA's) proposed approval of the plan's motor vehicle emissions budget (MVEB) is contingent on the submittal of a revised MVEB that includes road construction dust (see generally, 40 CFR 93.122(e)). We, therefore,

request that the Arizona Department of Environmental Quality (ADEQ) submit a revised MVEB for the Nogales PM I0 SIP that includes road construction dust, following the State's procedures for submitting

a SIP revision to EPA. We request that the revised MVEB be submitted to EPA expeditiously, so we

can resolve this issue in our final action which we expect to take in late July.

We regret our contribution to the omission of road constructi<m dust from the MVEB and appreciate the

extra time and effort it will take from your staff to make this correction. We look forward to continued

collaboration with ADEQ. If you have any questions or concerns, please contact me at (415) 972-3854,

or Jerry Wamsley at (415) 947-4111.

Lisa Hanf, Manager Planning Office, Air Division

Printed (HI Recvcled PaperThis page is intentionally blank.

### James Wagner

From: Beverly Chenausky [bchenausky@azdot.gov]

Sent: Friday, June 15, 2012 1:35 PM

To: James Wagner

Subject: Comments provided on Draft Nogales PM10 Nonattainment Plan 

### Pa g e 1 of 2

7/10/2012 Jim,

I have included a few comments on the pr oposed Nogales Moderate Area PM10 State Implementation Plan (SIP) for your review and consideration.

Page ES-5 – Last sentence first paragraph states “Each new travel plan” th e word travel should be replaced with transportation. Additionally because Nogales is an isolated rural area and does not contain a MPO the frequency requirement of c onformity with the MVEB of every four years is not applicable. In rural areas conformity done when an FHWA/FTA project needs approval not every four years, please remove reference to the four years in this sentence.

Page 2, Table 1.2 (and elsewhere) – General inquiry on why Census population is used instead of Department of Administration Population es timates? Please refer to Item 10 from The Governor’s Executive Order 2011-04 Designating th e Arizona Department of Administration as the State Agency Responsible fo r Preparing Official Populati on Estimates and Projections. http://azgovernor.gov/dms/upload/EO_2011

- 04.pdf

Page 24 – Wind Direction and Pollution Rose – it might be helpful for those not familiar with use of Wind Rose or meteorologica l terms to explain in more de scriptive detail what the Wind Rose and Pollution Rose show as multiple featur es are displayed in one diagram, as an example describe what the length and thic kness of the bar repres ents. The message is that the frequency of winds blowing (and pollution concentration) to Mexico from Arizona is small in comparison to the number of days the wind bl ows pollution to Arizona from Me xico, instead of referring to Appendix D maybe a summary of findings on what the data shows added to this section would

b e helpful. As a general observation, the SIP reli es heavily on referring people to an appendix for further explanation, some of the information c ontained in the appendixes should be summarized or described in more detail throughout the SIP.

Page 48 – In relation to MVEB Table 7.1, is it necessary to split out the Mobile portion into Gasoline and Diesel categories? It is likely that the personal vehicle fleet (gasoline fleet) would increase at a greater rate than diesel, any savings in emissions fr om diesel should be able to be used to offset any increase in gasoline emissi ons; as such this categor y should be combined. Additionally, please explain what emissions are contained in the Mobi le category directly in this section instead of referring to Appendix B a nd be consistent with the categories used. Specifically, Page 15 of Appendix B - States “EPA ran the MOVES model for 2011 to produce County-wide estimates for exhaust, brake, and tire-wear.” the budget in Table 7.1 should thereby list exhaust, brake and tire-wear for clarity. The EPA continues to explain that they “used a .569

ratio to reflect the emissions in non-attainment area” this is an important point to make directly in the SIP document for ensuring consistent planning assumptions between the SIP and any necessary conformity analysis.

Thank you,

Beverl y T. Chenausk y~~~~~~~~~~~~~~~~~~~~~~~ ~ Multimodal Planning Di vision - Air Quality Arizona Department of Transportation 206 South 17th Avenue, Mail Drop 320 Phoenix, AZ 85007 (602) 712-7487 Office (602) 712-3046 Fax bchenausky@azdot.gov



### ________________________________

Confidentiality and Nondisclosure Notice: This email transmission and any attachments are intended for use by the person(s)/ent ity(ies) named above and may contain confidential/privileged information. Any unauthorized use, disclosure or distribution is strictly prohibited. I f you are not the intended recipient, please contact the sender by email, and delete or destroy all copies plus attachments.

. 

### Pa g e 2 of 2

7/10/2012This page is intentionally blank.

### 1 Arizona Department of Environmental Quality Air Quality Division

July 23, 2012

RESPONSIVENESS SUMMARY

to Testimony Taken at Oral Proceeding and Written Comments Received on the Proposed Nogales PM 10 State Implementation Plan Revision

The oral proceeding on the proposed Nogales PM 10 State Implementation Plan (SIP) Revision was held at 2:00 p.m., Thursday, June 21, 2012, at the Nogal es Chamber of Commerce, 123 West Kino Park Place, Nogales, Arizona. No oral comments were received. The Arizona Department of Environmental Quality (ADEQ) received two written comments from organiza tions during the public comment period, which ended June 21, 2012. The public comments and ADEQ’s responses are described below.

Errata

EPA Region IX corrected minor miscalculations in emissions estimates for onroad mobile sources in Appendix B. The SIP was revised accordingly:

 On page ES-4, Figure ES-4, "O ther" emissions and annual PM 10 estimate were corrected.

 On page 13, paragraph 2, line 1, the annual PM 10 estimate for 2008 was corrected.

 On page 13, Figure 3.1, the annual PM 10 estimate for 2008 was corrected.

 On page 14, Table 3.2, the emissions estimates for onroad mobile sources were corrected.

 On page 15, Table 3.3, the emissions estimates for onroad mobile sources were corrected.

 On page 19, Figure 4.2, the annual PM 10 estimate was corrected.

 On page 47, paragraph 4, lines 5 and 6, the percentages for onroad emissions were corrected.

 On page 48, paragraph 1, line 1, the 2011 Motor Vehicle Emissions Budget was corrected.

 On page 48, Table 7.1, road the estimates for onroad mobile sources were corrected.

The following typographical and grammatical errors have been corrected in the Final version:

 On page 1, paragraph 2, line 1 was corrected from “ Section 1.1.2 describes the climate and physiography of the Nogales NA; Sections 1. 1.3 and 1.1.4 provide an overview of the demographics and economy of the Nogales area” to “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 demographics and economy of the Nogales area.”

 On page 4, paragraph 1, line 2, a duplicate footnote 8 was removed.

 On page 6, line 7, “Table 1.4” was changed to “Table 1.6”.

 On

 page 15, paragraph 1, line 7 was changed from "As discussed in Section 2.0...” to "As discussed in Section 1.0,"

 On page 16, footnote 20, line 2 was changed from " 2008 and 2011 Emissions Inventories for the Nogales NAA" to “2008 and 2011 Emissions Inventories for the Nogales NA”

 Figure 4.1 was moved from page 18 to page 17. Table 4.1 was moved from page 17 to page 18. The Table of Contents was updated to reflect these changes.

 On page 35, bullets 2 and 3, the date of the exceedance was changed from 28 to 26.

### 2  On page 38, paragraph 4, line 8 was changed from “DPSNA, and...” to “Nogales NA, and...”

 On Page 39, paragraph 3, line 2 was changed from “...where OHV’s can be used within its

borders” to “...where off-highway vehicles (OHVs) can be used within its borders...”

Public Comments

Commenter #1:

Comment: Page E5, paragraph one, last sentence, the co mmenter stated that the term “travel plan” should be changed to “transportation plan”. The commenter also stated that because Nogales is an isolated rural area and does not have a metropolitan planning organization, the frequency requirement to determine conformity with the motor vehicle emission budget (MVE B) is not every four years, but determined when new federal projects take place.

Response: On page ES-5, paragraph one, the last sentence was changed from “ Each new travel plan must be shown to conform with the motor vehicle em issions budget (MVEB) at least every four years and upon any amendments, including a new regional emissions analysis” to “Each new transportation plan must be shown to conform with the motor vehicle emissions budget (MVEB) and upon any amendments, including a new regional emissions analysis.”

Comment: The motor vehicle emissions budget (MVEB) on page 48 splits Mobile emissions into two categories, but it is likely that the personal vehicle fl eet (gasoline fleet) would increase at a greater rate than diesel, and any savings in emissions from diesel s hould be able to be used to offset any increase in gasoline emissions; as such, this category should be combined. This section should explain what emissions are contained in the Mobile category di rectly instead of referring to Appendix B. The categories used should be consistent.

Response: The third paragraph on page 47 explains the sources incl uded in MOVES projections. Table 7.1 on page 48 now combines diesel and gasoline emissions.

Comment: Page 15 of Appendix B states “EPA ran the MOVES model for 20 11 to produce county-wide estimates for exhaust, brake, and tire-wear." The budget in Table 7.1 should thereby list Exhaust, Brake and Tire-wear for clarity.

Response: Table 7.1 now lists Exhaust, Brake and Tire-Wear as sources included in Onroad emission

estimates.

Comment: In Appendix B, the EPA explains that in the 2011 emissions inventories EPA used a .569 ratio to allocate countywide emissions to the non-attainment ar ea. This is an important point to make directly in the SIP document for ensuring consistent pl anning assumptions between the SIP and any necessary conformity analysis.

Response: On page 47, two sentences were added to paragraph four to address the commenter's concerns. "The estimates were then scaled to the Nogales NA based on Census Bureau population data. To be conservative and to reflect the most current Census data , a 0.569 ratio was used instead of the 0.551 ratio used for 2008 population-based allocations."

### 3 Comment: The commenter asked why Census population da ta was used instead of Arizona Department of Administration data, as required by Executive Order 2011-04.

Response: 40 CFR 93.110 requires transportation conformity determinations to be based on the latest planning assumptions. For some categories in the emissions inventories in Chapter Four, EPA scaled countywide estimates to the nonattainment area b ased on population. After reviewing both 2010 U.S. Census population data and Arizona Department of Administrati on (ADOA) annual official estimates released December 15, 2010, EPA opted to use Census data to allocate population-based emissions. For clarity and consistency, Census data is used throug hout the SIP. The Arizona State Demographer's office approved the use of Census data in June 2011. ADOA is required to release new population projections based on U.S. Census data by December 31, 2012, to replace projections last issued by Arizona in 2006.

Commenter #2

Comment: The MVEB must include emissions from road construction projects to meet the requirements established in CFR 93.122(e).

Response: Road construction emissions estimates are now included in the MVEB.

### ARIZONA DEPARTMENT OF ENVIR ONMENTAL QUALITY 30 DAY PUBLIC

COMMENT PERIOD AND OPPORTUNITY TO REQUEST A HEARING ON

REVISIONS TO THE NOG ALES MODERATE PM 10 

### MAINTENANCE PLAN

The Arizona Department of Environmenta l Quality (ADEQ) is holding 30 day public comment period beginning with the publica tion of this notice on July  , 2012, for further revisions to the proposed Nogales Moderate Area PM 10 

### State Implementation Plan (SIP). In response to comments received dur ing the initial public comment period that began May 18, 2012, and ended June 21, 2012. Th e SIP was revised to include road construction dust in the Motor Vehicle Emissions Budget (MVEB) and correct

mathematical errors in estimates for onroa d mobile emissions in both the emissions inventory and MVEB.

If a request for a hearing is received by August 15, 2012, ADEQ will hold a hearing for the SIP revisions at 10:00 a.m., Augus t 23, 2012, at ADEQ, 1110 W. Washington Street, Phoenix, Arizona, 85007. If no request is rece ived, the hearing will be cancelled and acancellation notice will be posted on ADEQ's calendar (http://www.azdeq.gov/cgibin/vertical.pl ).The public may also cal l (602) 771-2388 to find out if the hearing has

been cancelled.

All interested parties will be given an opportu nity at the public hear ing to submit relevant comments, data, and views, orally and in writing. Written comments may be submitted prior to or during the public hearing and must be postmar ked or received by at ADEQ by 5:00 p.m. on August 23, 2012.

All written comments should be a ddressed, faxed, or e-mailed to:

Jim Wagner Arizona Department of Environmen tal Quality - Air Quality Division 1110 West Washington Street, Phoenix, AZ 85007 FAX: (602) 771-2366 E-Mail: JW3@azdeq.gov

Copies of the revised PM 10 

### SIP proposal are available for review online at the following web address http://www.azdeq.gov/cgi-bin/vertical.pl and in hard copy at the following

locations:

ADEQ Records Center First Floor, 1110 W. Washington Street Phoenix, Arizona 85007 Attention: Norlene Lara, (602) 771-4712

Nogales Library

777 E. Grand Avenue Nogales, AZ 85621 Attention: Suzanne Haddock, (520) 287- 6571This page is intentionally blank.