2015 West Pinal Moderate 

PM10 Nonattainment Area 

SIP

Air Quality Division

December 21, 2015 Final 
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Table of Contents

1 EXECUTIVE SUMMARY ........................................................................................................ 9

2 COMPLETENESS CRITERIA (40 C.F.R. Part 51, Appendix V) .............................................. 13

2.1 Administrative Materials ...................................................................................... 13

2.1.1 A formal letter of submittal from the Governor or his [her] designee, 

requesting EPA approval of the plan or revision thereof (hereafter ‘‘the 

plan’’). .................................................................................................... 13

2.1.2 Evidence that the State has adopted the plan in the State code or body 

of regulations; or issued the permit, order, consent agreement 

(hereafter ‘‘document’’) in final form. .................................................. 13

2.1.3 Evidence that the State has the necessary legal authority under State 

law to adopt and implement the plan. .................................................. 13

2.1.4 A copy of the actual regulation, or document submitted for approval 

and incorporation by reference into the plan, including indication of the 

changes made to the existing approved plan, where applicable. ......... 14

2.1.5 Evidence that the State followed all of the procedural requirements of 

the State’s laws and constitution in conducting and completing the 

adoption/issuance of the plan............................................................... 16

2.1.6 Evidence that public notice was given of the proposed change 

consistent with procedures approved by EPA, including the date of 

publication of such notice...................................................................... 17

2.1.7 Certification that public hearing(s) were held in accordance with the 

information provided in the public notice and the State’s laws and 

constitution, if applicable and consistent with the public hearing 

requirements in 40 CFR 51.102. ............................................................ 17

2.1.8 Compilation of public comments and the State’s response thereto..... 17

2.2 Technical Support ................................................................................................. 17

2.2.1 Identification of all regulated pollutants affected by the plan.............. 17

2.2.2 Identification of the locations of affected sources including the EPA 

attainment/ nonattainment designation of the locations and the status 

of the attainment plan for the affected areas(s)................................... 17

2.2.3 Quantification of the changes in plan allowable emissions from the 

affected sources; estimates of changes in current actual emissions from 

affected sources or, where appropriate, quantification of changes in 

actual emissions from affected sources throughcalculations of the 

December 21, 2015 Final 1
differences between certain baseline levels and allowable emissions 

anticipated as a result of the revision. .................................................. 18

2.2.4 The State’s demonstration that the national ambient air quality 

standards, prevention of significant deterioration increments, 

reasonable further progress demonstration, and visibility, as applicable, 

are protected if the plan is approved and implemented (Section 110(l)

demonstration). ..................................................................................... 18

2.2.5 Modeling information required to support the proposed revision, 

including input data, output data, models used, justification of model 

selections, ambient monitoring data used, meteorological data used, 

justification for use of offsite data (where used), modes of models used, 

assumptions, and other information relevant to the determination of 

adequacy of the modeling analysis........................................................ 18

2.2.6 Evidence, where necessary, that emission limitations are based on 

continuous emission reduction technology........................................... 18

2.2.7 Evidence that the plan contains emission limitations, work practice 

standards and recordkeeping/reporting requirements, where 

necessary, to ensure emission levels..................................................... 19

2.2.8 Compliance/enforcement strategies, including how compliance will be 

determined in practice........................................................................... 19

2.2.9 Special economic and technological justifications required by any 

applicable EPA policies, or an explanation of why such justifications are 

not necessary......................................................................................... 19

3 INTRODUCTION................................................................................................................. 21

3.1 Statement of Introduction and Purpose............................................................... 21

3.2 National Ambient Air Quality Standards............................................................... 21

3.3 U.S. EPA's Particulate Matter NAAQS ................................................................... 22

3.4 Regulatory Background......................................................................................... 23

3.5 West Pinal County PM10 Nonattainment Area Description.................................. 24

3.5.1 West Pinal County PM10 Nonattainment Area Boundary...................... 24

3.5.2 Geography and Climate ......................................................................... 26

3.5.3 Population.............................................................................................. 27

3.5.4 County Economy .................................................................................... 28

3.6 General SIP Approach - Regulatory Requirements and Guidance........................ 30

3.6.1 Clean Air Act Requirements for Nonattainment Area Plans ................. 30

3.6.2 EPA Guidance......................................................................................... 39

4 AMBIENT AIR QUALITY MONITORING .............................................................................. 41

December 21, 2015 Final 2
4.1 Monitoring Site, Equipment, and Quality Assurance Procedures........................ 41

4.2 Historical PM10 Data Summary.............................................................................. 45

4.3 24-Hours PM10 NAAQS Compliance - 2012-2014 ................................................. 46

5 ANNUAL EMISSIONS INVENTORY ..................................................................................... 48

5.1 Meteorological Scenarios and General Methodology.......................................... 48

5.2 Windblown Methodologies for the Base Years 2008 and 2018........................... 49

5.2.1 Annual Windblown Methodologies....................................................... 49

5.2.2 Adjusting and Projecting the 2008 Base Year Emissions to 2018.......... 53

5.3 Activity-Based Emissions for the Base Years 2008 and 2018 ............................... 54

5.3.1 Agriculture Crop Emissions.................................................................... 54

5.3.2 Concentrated Animal Feeding Operations (CAFO) Emissions............... 55

5.3.3 Dairy Emissions...................................................................................... 56

5.3.4 Fugitive Dust and Exhaust Emissions from Paved Roads....................... 56

5.3.5 Fugitive Dust and Exhaust Emissions from Unpaved Roads.................. 57

5.3.6 Nonroad Emissions ................................................................................ 58

5.3.7 Railroad Emissions................................................................................. 58

5.3.8 Construction Emissions.......................................................................... 59

5.3.9 Emissions from Permitted Stationary Sources ...................................... 59

5.3.10 Fuel Combustion Sources ...................................................................... 59

5.3.11 Unpaved Parking.................................................................................... 60

5.4 Comparison of Base Year Inventories to Control Inventories.............................. 60

5.5 Motor Vehicle Emissions Budget (MVEB) Summary............................................. 61

6 CONTROL MEASURES........................................................................................................ 64

6.1 Agricultural Rule – Attainment and Contingency in Part...................................... 64

6.1.1 Commercial Farms Summary (R18-2-610 and -610.03) ........................ 64

6.1.2 Appendix 2 – Test Method for Silt Loading ........................................... 65

6.1.3 Commercial Animal Operations Summary (R18-2-611 and -611.03).... 65

6.1.4 Irrigation Districts in the Pinal County PM Nonattainment Area (R18-2-

612 and -612.01).................................................................................... 66

6.1.5 Implementation Schedule – Agricultural Rules..................................... 66

6.1.6 Enforceability ......................................................................................... 66

6.1.7 Credited Annual Emission Reductions from Agricultural BMP Rules.... 76

6.2 Fugitive dust – Contingency Measure .................................................................. 77

December 21, 2015 Final 3
6.2.1 Fugitive Dust Rule Summary.................................................................. 77

6.2.2 Planned Rule Implementation Schedule – General Fugitive Dust Rule. 77

6.2.3 Enforceability ......................................................................................... 77

6.2.4 Credited Annual Emissions Reductions from Fugitive Dust Rule .......... 81

6.3 Construction Rule - Contingency .......................................................................... 82

6.3.1 Construction Rule Summary .................................................................. 82

6.3.2 Planned Rule Implementation ............................................................... 82

6.3.3 Enforceability ......................................................................................... 82

6.3.4 Credited Annual Emissions Reductions ................................................. 84

6.4 Statutory Amendments......................................................................................... 85

6.4.1 Agricultural Best Management Practices - Arizona Revised Statutes 

(A.R.S.) § 49-457..................................................................................... 85

6.4.2 High Risk Forecast - Arizona Revised Statutes (A.R.S.) § 49-424(11)..... 86

6.5 Adequate Resources............................................................................................. 86

6.5.1 Adequate Resources – Agricultural Rules.............................................. 86

6.5.2 Adequate Resources - Fugitive Dust and Construction Rules ............... 87

7 ATTAINMENT DEMONSTRATION AND REASONABLE FURTHER PROGRESS ..................... 89

7.1 Attainment Demonstration................................................................................... 89

7.1.1 Stagnation Attainment Modeling Background ...................................... 90

7.1.2 High Wind Attainment Modeling Background....................................... 92

7.1.3 How ADEQ Accounted for Attainment Controls.................................... 97

7.1.4 Comparative Concentration Table......................................................... 98

7.1.5 Annual Inventory Attainment Reductions............................................. 99

7.2 Reasonable Further Progress................................................................................ 99

List of Figures

Figure 1-1 Pinal County at a Glance................................................................................................ 9

Figure 3-1 Map of West Pinal County PM10 Nonattainment Area ............................................... 25

Figure 3-2 Casa Grande National Monument, Arizona, Monthly Average Temperatures and 

Precipitation: 1981-2010 Normals................................................................................................ 27

Figure 4-1 West Pinal County PM10 Nonattainment Area ............................................................ 42

Figure 4-2 Three-Year Average Expected Rate of Exceedance..................................................... 46

Figure 7-1 Reasonable Further Progress from Dec. '15 through Dec. '18 .................................. 101

Figure 7-2: Reasonable Further Progress from Dec. '15 through Dec. '18................................. 101

December 21, 2015 Final 4
List of Tables

Table 2-1 Rules and Statutes to Be Added to and Removed from the SIP................................... 14

Table 3-1 PM10 NAAQS History ..................................................................................................... 22

Table 3-2 Names and Elevations of West Pinal County Cities...................................................... 26

Table 3-3 West Pinal County PM10 Nonattainment Area Population Distribution – 2008 

Emissions Inventory Base Year ..................................................................................................... 28

Table 3-4 Pinal County Civilian Employed Population 16 Years and Over – 2013 U.S. Census 

Bureau........................................................................................................................................... 29

Table 3-5 Annual New Privately-Owned Residential Building Permits......................................... 30

Table 3-6 Clean Air Act (CAA) Requirements for Moderate PM10 Nonattainment Area SIPs...... 31

Table 4-1 Active Monitors within the West Pinal County PM10 Nonattainment Area................. 43

Table 4-2 2012 to 2014 Maximum 24-Hour Average PM10 Compliance ...................................... 47

Table 5-1 Land Use Categories for Windblown Emissions ........................................................... 50

Table 5-2 Activity-Based Emission Source Categories.................................................................. 54

Table 5-3 Comparing Base Year 2008 to Base Year 2018 to Post Control 2018 Inventories ....... 60

Table 5-4 Annual MVEB by Source Sector .................................................................................... 62

Table 6-1 Commercial Farms Rule Test Methods......................................................................... 69

Table 6-2 CAFO Rule Test Methods.............................................................................................. 72

Table 6-3 Irrigation Districts Rule Test Methods.......................................................................... 74

Table 6-4 Agricultural Best Management Practices Rule Reductions .......................................... 76

Table 6-5 General Fugitive Dust Rule Test Methods.................................................................... 80

Table 6-6 Fugitive Dust Rule Attributable Annual Inventory Reductions (TPY) ........................... 81

Table 6-7 Construction Rule Test Methods.................................................................................. 84

Table 6-8 Annual Inventory Reductions Attributable to Construction Rule (TPY) ....................... 84

Table 7-1 Values used for Example Windblown Dust Calculation................................................ 95

Table 7-2 Comparative Design Day Concentration between Base 2008, Projected 2018, and 

Projected Controlled 2018............................................................................................................ 98

Table 7-3 Annual Inventory Reductions from the Attainment Targeting Sections of the Ag BMP 

Rules (TPY) .................................................................................................................................... 99

Table 7-4 Summary of Contingency Measure Reductions.......................................................... 102

List of Appendices

Appendix A: Pinal County PM Inventory Preparation Plan (IPP) 

Appendix B: Pinal County PM10 Nonattainment Area Emissions Inventories for 2008 and 2018 

Base Years and Design Days (EI TSD)

December 21, 2015 Final 5
Appendix C: Pinal County PM10 Nonattainment Area Source Apportionment Modeling for 

2008 and 2018 Base Scenario Design Days (Modeling TSD)

Appendix D: Pinal County PM10 Nonattainment Area 2018 Attainment Demonstration and 

Controlled Emissions Inventories (Attainment TSD)

Appendix E: Procedural Requirements and Authority 

Appendix F: Reasonably Available Control Measures Analysis (RACM)

Appendix G: Rules, Statutes, or Other Documents for Approval

Appendix A: Pinal County PM Inventory Preparation Plan (IPP) 

Appendix A-A 2008 24-Hour Average PM10 Concentrations Recorded at Six 

Pinal County TEOM Monitoring Sites

Appendix A-B Plots of Hourly PM10 Concentration, Wind Speed, Wind 

Direction, and Mixing Height Modeled at Cowtown, Pinal County 

Housing, and Stanfield Monitoring Sites on October 29, 2008

Appendix A-C Statistics of the High Wind PM10 Exceedance Days at Cowtown 

in 2008

Appendix A-D Statistics of the High Wind PM10 Exceedance Days at Stanfield in 

2008

Appendix A-E Statistics of the High Wind PM10 Exceedance Days at Pinal 

County Housing in 2008

Appendix A-F Statistics of the PM10 Exceedance Days at Maricopa in 2008

Appendix A-G Statistics of the PM2.5 Exceedance Days at Cowtown in 2008

Appendix A-H Road Count Data

Appendix A-I Method for the Back-Calculation of Wind-Blown Emission Factors 

from Field Measured PM10 Concentrations, Arizona Department 

of Environmental Quality Air Quality Division

Appendix A-J MAG 2012 Five Percent Plan for PM10 for the Maricopa County 

Nonattainment Area, May 2012

Appendix B: Pinal County PM10 Nonattainment Area Emissions Inventories for 2008 and

2018 Base Years and Design Days (EI TSD)

Exhibit B-I Analysis of Unpaved Roads in the Pinal County PM10 

Nonattainment Area

Exhibit B-II Pinal County Field Sampling and Analysis for the Silt 

Characterization of Unpaved Road Dust and Agricultural Soil

Exhibit B-III Pinal County Crops Calendar and High Wind Crop Disturbance 

Description

Exhibit B-IV Traffic Counts (ADT levels) for the Unpaved Roads in Each of the 

Modeling Domain

Exhibit B-V Methodology for Estimating Windblown Emission Factors within 1 

MPH Wind Speed Bins

Exhibit B-VI Evaluation of a Wind Erosion PM10 Emission Equation for 

Agricultural Lands in the Western Pinal County PM10 

Nonattainment Area

December 21, 2015 Final 6
Exhibit B-VII Ambient Monitoring Data Based Emission Factor Adjustment 

Arizona Department of Environmental Quality (ADEQ) Air Quality 

Division

Exhibit B-VIII NONROAD Input Files (2008 and 2018)

Exhibit B-IX Agricultural Unpaved Road Activity and Speed Notes

Exhibit B-X Listing of Diurnal Profiles for Windblown, Activity-Based, and Total 

Emissions on High Wind Days

Exhibit B-XI Pinal County Land Use Descriptions

Exhibit B-XII Selection of Cowtown PM10 Stagnation Design Day

Exhibit B-XIII Cowtown Stagnation Design Day Modeling Domain Comparison: 

October 29, 2008 vs. October 30, 2008

Exhibit B-XIV Shape Files Used in Inventory Development and Modeling

Exhibit B-XV Documentation of Control Efficiency for Nissan and Volkswagen 

Test Tracks

Exhibit B-XVI. West Pinal County PM10 Precursor Significance Determination

Appendix C: Pinal County PM10 Nonattainment Area Source Apportionment Modeling for 

2008 and 2018 Base Scenario Design Days (Modeling TSD)

Exhibit C-I High Wind Design Day Example Calculation

Appendix D: Pinal County PM10 Nonattainment Area 2018 Attainment Demonstration and

Controlled Emissions Inventories (Attainment TSD)

Exhibit D-I Agricultural Supplemental Information

Exhibit D-II MAG Methodology for MOVES2014

Appendix E: Procedural Requirements and Authority 

Exhibit E-I Delegation of Authority

Exhibit E-II Authorizing Statutes

Exhibit E-III Public Notice and Affidavit of Publication of Notice 

Exhibit E-IV Public Hearing Agenda

Exhibit E-V Public Hearing Sign-in Sheet

Exhibit E-VI Public Hearing Officer Certification

Exhibit E-VII Compilation of Comments and State Responses

Exhibit E-VIII Public Hearing Transcript

Appendix F: Reasonably Available Control Measures Analysis (RACM)

Exhibit F-I Available Measures

Exhibit F-II Construction Comparison

Exhibit F-III Agricultural Comparison

Exhibit F-IV Fugitive Dust Comparison

Exhibit F-V Information on Gallons per Head Standard Providing More 

Benefits over a Strict Moisture Percentage for Feed Yard Pens

Appendix G: Rules, Statutes, or Other Documents for Approval

Exhibit G-I Certified A.R.S. § 49-424 (2015) Duties of department (revised

high risk forecast mandate included)

Exhibit G-II House Bill 2125, Amending A.R.S. § 49-424 (Fifty-first Legislature, 

Second Regular Session, 2014, Chapter 86) (reflecting changes 

from most recent approved version)

December 21, 2015 Final 7
Exhibit G-III History of A.R.S. § 49-457: House Bill 2394, Fifty-second 

Legislature, First Regular Session, 2015, Chapter 243, § 1, 

amending A.R.S. § 49-457; A.R.S. § 49-457 (2011); A.R.S. § 49-457 

(2005) (same as approved version)

Exhibit G-IV Certified A.R.S. § 49-457 Agricultural best management practices 

committee; members; powers; permits; enforcement; 

preemption; definitions (effective January 1, 2016) (last amended 

by House Bill 2394, Fifty-second Legislature, First Regular Session, 

2015, Chapter 243, § 1)

Exhibit G-V Redline Version of Changes from SIP Approved to Current Version 

of A.R.S. § 49-457 effective January 1, 2016

Exhibit G-VI Certified Final Rule - ADEQ Enforced Agricultural Best 

Management Practices Committee Rules for West Pinal County 

PM10 Nonattainment Area (Agricultural BMP Rules)

Exhibit G-VII Certified Final Rule - Pinal County Construction Sites - Fugitive 

Dust Rule for West Pinal PM10 Nonattainment Area (Construction 

Rule)

Exhibit G-VIII Certified Final Rule - Pinal County West Pinal PM10 Moderate 

Nonattainment Area Fugitive Dust Rule (Fugitive Dust Rule)

Appendix H: Pinal County Rulemaking Process Documentation – Construction Rule

Appendix I: Pinal County Rulemaking Process Documentation – General Fugitive Dust Rule

December 21, 2015 Final 8
1 EXECUTIVE SUMMARY

The West Pinal County PM10

1 Nonattainment Area is in Central Arizona, located within a basin 

between the Phoenix and Tucson metropolitan areas. Pinal County as a whole encompasses 

5,365.612 square miles and has two distinct regions: the eastern portion which is characterized 

by mountains with elevations up to 6,441 feet and the western region primarily comprised of 

low desert valleys and irrigated agriculture. Figure 1-1 illustrates the geographical location of 

Pinal County within the State of Arizona. 

Source: Pinal County Economic Development.3

1 Particulate matter with a diameter of 10 microns or less 2 United States Census Bureau, Pinal County, Arizona QuickFacts Beta, (June 29, 2015) 

http://quickfacts.census.gov/qfd/states/04/04021.html. 

3 Pinal County at Glance, http://www.pinalcountyaz.gov/ed/Pages/Home.aspx (last visited Jun. 29, 2015).

Figure 1-1 Pinal County at a Glance

December 21, 2015 Final 9

 
Effective July 2, 2012, the U.S. Environmental Protection Agency redesignated a portion of 

western Pinal County from "unclassifiable” to “nonattainment” area for the 1987 24-hour PM10

National Ambient Air Quality Standards (NAAQS).4 The 24-hour PM10 standard was 

promulgated in 1987 to be 150 micrograms per cubic meter (μg/m3), meaning that an air 

quality monitor cannot measure levels of PM10 greater than 150 micrograms per cubic meter 

(μ/m3

) more than once per year on average over a consecutive three-year period. 5

The designation of the West Pinal County PM10 nonattainment area is based on recorded 

violations of the PM10 standard at various monitoring sites within the county. The boundaries of 

the nonattainment area encompass land that is located within Pinal County north of the eastwest line, defined by the southern line of Township 9 South, Gila and Salt River Baseline and 

Meridian, and west of the north-south line, defined by the eastern line of Range 8 East, except 

for Indian Country, certain federal land, and where the boundary extends farther east in the 

Florence and Picacho Peak areas.6

This State Implementation Plan for the West Pinal County PM10 Nonattainment Area consists of 

the following additional six chapters:

Chapter 2 - COMPLETENESS CRITERIA (40 C.F.R. Part 51, Appendix V)– Notes the Appendix V 

requirements and their respective locations in the rules

Chapter 3 – INTRODUCTION– Provides an introduction to the physical, demographic, economic 

description of the area, as well as to the regulatory background of the PM10 NAAQS 

in Pinal County.

Chapter 4 – AMBIENT AIR QUALITY MONITORING– Describes how the Pinal County Ambient 

Monitoring Network meets the Clean Air Act and U.S. Environmental Protection 

Agency regulatory requirements.

Chapter 5 – ANNUAL EMISSIONS INVENTORY– Provides the base year emission inventory for 

the nonattainment area. It summarizes the methodologies used to develop the 

inventory as required by the Clean Air Act Section 172(c)(3) and to project it from 

the base year to the attainment year. Additionally, this section summarizes the 

development and quantification of the motor vehicle emissions budget (MVEB). 

Chapter 6 – CONTROL MEASURES– Identifies significant sources of emissions within the West 

Pinal County Nonattainment Area and presents a summary and analyses of the 

control measures chosen to achieve attainment and reasonable further progress

4 Redesignation of West Pinal County as Nonattainment for PM10, 77 Fed. Reg. 32024 (May 31, 2012) (codified at 

40 C.F.R. pt. 81.303). 5 As calculated rounding to the nearest 10 μg/m3

, according to 40 C.F.R. § 50, Appendix K (2015) (effective 2006). 6 Redesignation, supra note 4, at 32029.

December 21, 2015 Final 10

 
(RFP). The section also summarizes the development and quantification of the 

emissions reductions needed to meet contingency measure goals.

Chapter 7 – ATTAINMENT DEMONSTRATION AND REASONABLE FURTHER PROGRESS– Presents 

a summary of the 2008 and 2018 base year modeling for selected design days and 

modeling domains. Summarizes the modeling methodology and results when 

incorporating additional controls to demonstrate attainment.

December 21, 2015 Final 11
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December 21, 2015 Final 12
2 COMPLETENESS CRITERIA (40 C.F.R. Part 51, 

Appendix V)

2.1 Administrative Materials

2.1.1 A formal letter of submittal from the Governor or his [her]

designee, requesting EPA approval of the plan or revision thereof 

(hereafter ‘‘the plan’’).

See the cover letter for this SIP submission and attached delegation of authority from Misael 

Cabrera, Director of ADEQ, to Eric Massey, Director of the ADEQ Air Quality Division, 

authorizing Mr. Massey to perform any act the ADEQ Director is authorized to perform under 

the state air quality statutes, including the submission of SIPs to EPA.

2.1.2 Evidence that the State has adopted the plan in the State code or 

body of regulations; or issued the permit, order, consent 

agreement (hereafter ‘‘document’’) in final form.

See cover letter to this document wherein the state adopts and submits this SIP revision. This is 

the method of Arizona state adoption. The rules were adopted into Arizona law once finalized

and are effective January 1, 2016. See Appendix G for the certified rules. Additionally, Pinal 

County’s Board of Supervisors adopted the construction and fugitive dust rules as law. See 

Appendix H and Appendix I for more information.

2.1.3 Evidence that the State has the necessary legal authority under 

State law to adopt and implement the plan.

The Arizona Department of Environmental Quality has responsibility for air pollution control 

and abatement, and as such, is required to adopt and "maintain a state implementation plan 

that provides for implementation, maintenance and enforcement of national ambient air 

quality standards and protection of visibility as required by the clean air act." A.R.S. § 49-

404(A). ADEQ also maintains authority to issue and administer rules, adopt county rules, and to 

submit such rules for approval in the SIP. Copies of Arizona Revised Statutes sections 49-104, 

49-106, 49-404, 49-406 and 49-425, are attached as Appendix E, Exhibit E-II. 

December 21, 2015 Final 13
2.1.4 A copy of the actual regulation, or document submitted for 

approval and incorporation by reference into the plan, including 

indication of the changes made to the existing approved plan, 

where applicable.

Appendix G includes the rules and statutes submitted for Approval into the SIP, as well as 

comparative redlines. Table 2-1 below lists the regulations being added and replaced by this 

SIP Revision. In order to promote maximum consistency between state and federal law ADEQ 

requests that EPA remove each of the rules or statutes identified in the third column of the 

table from the approved SIP.

Table 2-1 Rules and Statutes to Be Added to and Removed from the SIP

Rule or Statute Added Overarching Arizona 

Administrative Register or 

Legislative Citation

SIP Rule(s) Replaced (Federal 

Register Citation)

A.R.S. § 49-424 (2015) Duties of department 

(revised high risk forecast mandate included)

A.R.S. § 49-424 as amended by 

Laws 2014, Ch. 86, § 1 (House 

Bill 2125)

A.R.S. § 49-424 (2011) Duties of 

department (77 FR 66398, Nov.

5, 2012)

A.R.S. § 49-457 (2015) Agricultural best 

management practices committee; members; 

powers; permits; enforcement; preemption; 

definitions 

A.R.S. § 49-457 (effective 

January 1, 2016) as amended 

by Laws 2015, Ch. 243, § 1 

(House Bill 2394)

A.R.S. § 49-457 (1998)

Agricultural best management 

practices committee; 

members; powers; permits; 

enforcement; preemption; 

definitions (64 FR 34726, Jun.

29, 1999)

December 21, 2015 Final 14
Rule or Statute Added Overarching Arizona 

Administrative Register or 

Legislative Citation

SIP Rule(s) Replaced (Federal 

Register Citation)

A.A.C., Title 18, Chapter 2, Article 2. 

Sections

R18-2-210. Ambient Air Quality Standards; 

Area Designations; Classifications 

A.A.C. Title 18, Chapter 2, Article 6. 

Emissions from Existing and New Nonpoint 

Sources

Sections

R18-2-610. Definitions for R18-2-610.01, R18-

2-610.02, and R18-2-610.03 

...

R18-2-610.03. Agricultural PM General Permit 

for Crop Operations; Pinal County PM 

Nonattainment Area 

R18-2-611. Definitions for R18-2-611.01, R18-

2-611.02, and R18-2-611.03

...

R18-2-611.03. Agricultural PM General Permit 

for Animal Operations; Pinal County PM 

Nonattainment Area 

R18-2-612. Definitions for Definitions for R18-

2-612.01

R18-2-612.01. Agricultural PM General Permit 

For Irrigation Districts; PM Nonattainment 

Areas Designated After June 1, 2009 

...

Appendix 2. Test Methods And Protocols

(Other rules were included in this rulemaking, 

but ADEQ intends to submit them in a 

subsequent revision)

Notice of Final Exempt 

Rulemaking, 21 A.A.R. 1156, 

July 24, 2015 (effective July 2, 

2015).

A.A.C. R18-2-210 (2012)

Attainment, Nonattainment, 

and Unclassifiable Area 

Designations (79 FR 56655, 

Sept. 23, 2014)

ADEQ is not requesting rule 

replacement of any of the 

A.A.C. Title 18, Chapter 2, 

Article 6 agricultural rules at 

this time. ADEQ is only 

requesting additions, currently. 

ADEQ will request any 

replacements in a subsequent

SIP revision submittal. 

December 21, 2015 Final 15
Rule or Statute Added Overarching Arizona 

Administrative Register or 

Legislative Citation

SIP Rule(s) Replaced (Federal 

Register Citation)

Pinal County Code of Regulations, Chapter 4, 

Article 3, Construction Sites – Fugitive Dust 

Sections

§ 4-3-160. General Provisions – West Pinal 

PM10 Nonattainment Area

§ 4-3-170. Definitions

§ 4-3-180. Dust Generating Operations 

Standards, Application, Permit and 

Recordkeeping Requirements 

§ 4-3-190. Violations 

(§ 1-1-105. SIP List was also revised in this 

rulemaking but is not appropriate for 

inclusion in the SIP. ADEQ is not requesting 

approval for this section into the SIP.)

Notice of Final Rulemaking, 21 

A.A.R. 2937, November 20, 

2015 (effective January 1, 

2016).

None

Pinal County Air Quality Control District Code 

of Regulations, Chapter 4, Article 1, West 

Pinal PM10 Moderate Nonattainment Area 

Fugitive Dust

Sections

§ 4-1-010. General Applicability

§ 4-1-015. Exemptions

§ 4-1-020. Definitions

§ 4-1-030. Standards

§ 4-1-040. Recordkeeping

§ 4-1-045. Reporting Requirements

§ 4-1-050. Records Retention

§ 4-1-060. Violations

(§ 1-1-105. SIP List was also revised in this 

rulemaking but is not appropriate for 

inclusion in the SIP. ADEQ is not requesting 

approval for this section into the SIP.)

Notice of Final Rulemaking, 21 

A.A.R. 2925, November 20, 

2015 (effective January 1, 

2016).

None

2.1.5 Evidence that the State followed all of the procedural requirements 

of the State’s laws and constitution in conducting and completing 

the adoption/issuance of the plan.

As demonstrated in Sections 2.1.2, 2.1.3 and 2.1.7 ADEQ has complied with all requirements of 

state law for adoption of the rule revisions included in this SIP Revision. 

December 21, 2015 Final 16
2.1.6 Evidence that public notice was given of the proposed change 

consistent with procedures approved by EPA, including the date of 

publication of such notice.

Proof that ADEQ gave notice of the SIP Revision in accordance with A.R.S. § 49-444 is attached 

as Appendix E, Exhibit E-III.

2.1.7 Certification that public hearing(s) were held in accordance with 

the information provided in the public notice and the State’s laws 

and constitution, if applicable and consistent with the public 

hearing requirements in 40 CFR 51.102.

The certification and other documents related to the public hearing are attached as Appendix E, 

Exhibits E-III through E-VIII.

2.1.8 Compilation of public comments and the State’s response thereto.

A compilation of comments received and the State’s responses are attached as Appendix E, 

Exhibit E-VII.

2.2 Technical Support

2.2.1 Identification of all regulated pollutants affected by the plan.

This plan includes provisions for the regulation of PM10 emissions. See Section 3.1, Statement 

of Introduction and Purpose and Chapter 6, Control Measures.

2.2.2 Identification of the locations of affected sources including the EPA 

attainment/ nonattainment designation of the locations and the 

status of the attainment plan for the affected areas(s).

This nonattainment plan is applicable to sources within the West Pinal PM10 Nonattainment 

Area. See Section 3.5.1 and Chapter 5, Annual Emissions Inventory.

December 21, 2015 Final 17
2.2.3 Quantification of the changes in plan allowable emissions from the 

affected sources; estimates of changes in current actual emissions 

from affected sources or, where appropriate, quantification of 

changes in actual emissions from affected sources through 

calculations of the differences between certain baseline levels and 

allowable emissions anticipated as a result of the revision.

Calculated emissions reductions due to implementation of control strategies contained in this 

plan are provided in Section 5.4 Comparison of Base Year Inventories to Control Inventories and 

Chapter 6, Control Measures.

2.2.4 The State’s demonstration that the national ambient air quality 

standards, prevention of significant deterioration increments, 

reasonable further progress demonstration, and visibility, as 

applicable, are protected if the plan is approved and implemented 

(Section 110(l) demonstration).

As is indicated in Section 2.1.4, this SIP revision will add to or replace existing SIP rules with 

requirements that are either as stringent or more stringent. The control strategies contained in 

this plan are expected to reduce emissions sufficient to demonstrate attainment of the PM10

NAAQS in the West Pinal PM10Nonattainment Area. None of the changes will interfere with 

any applicable requirement concerning attainment, reasonable further progress, increments or 

visibility. 

2.2.5 Modeling information required to support the proposed revision, 

including input data, output data, models used, justification of 

model selections, ambient monitoring data used, meteorological 

data used, justification for use of offsite data (where used), modes 

of models used, assumptions, and other information relevant to the 

determination of adequacy of the modeling analysis.

EPA approved the use of AERMOD and Rollback modeling to demonstrate attainment of the 

PM10NAAQS. Details of the analyses are included in Chapter 7, Attainment Demonstration And 

Reasonable Further Progress, Appendix C: Pinal County PM10 Nonattainment Area Source 

Apportionment Modeling for 2008 and 2018 Base Scenario Design Days (Modeling TSD), and 

Appendix D: Pinal County PM10 Nonattainment Area 2018 Attainment Demonstration and 

Controlled Emissions Inventories (Attainment TSD).

2.2.6 Evidence, where necessary, that emission limitations are based on 

continuous emission reduction technology.

Not Applicable.

December 21, 2015 Final 18
2.2.7 Evidence that the plan contains emission limitations, work practice 

standards and recordkeeping/reporting requirements, where 

necessary, to ensure emission levels.

Information on emissions limits and recordkeeping/reporting requirements is included in 

Chapter 6, Control Measures and in the agriculture, construction, and general fugitive dust

control rules in Appendix G: Rules, Statutes, or Other Documents for Approval.

2.2.8 Compliance/enforcement strategies, including how compliance 

will be determined in practice.

Compliance and enforcement of the agriculture, construction, and general fugitive dust control 

strategies included in this plan are discussed in Sections 0, 6.2.3, and 6.3.3.

2.2.9 Special economic and technological justifications required by any 

applicable EPA policies, or an explanation of why such 

justifications are not necessary.

This plan does not rely on any special economic and technological justifications in support of 

the control strategies contained within.

December 21, 2015 Final 19
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December 21, 2015 Final 20
3 INTRODUCTION

This chapter describes the purpose of this West Pinal County PM10 Nonattainment Area SIP 

revision, summarizes the regulatory background and requirements for the area, and provides a 

general overview of the nonattainment area and County. 

3.1 Statement of Introduction and Purpose

Pursuant to Section 107(d)(3) of the Clean Air Act (CAA), the U.S. Environmental Protection 

Agency (EPA) redesignated an area in western Pinal County from an “unclassifiable” area to a 

“moderate” nonattainment area for the 1987 24-hour PM10 National Ambient Air Quality 

Standards (NAAQS). The EPA based its redesignation on recorded violations of the standard at 

ambient monitoring sites within the County. 

Under the authority granted by the Governor and the State of Arizona, the Arizona Department 

of Environmental Quality (ADEQ) is responsible for the preparation and submittal of this State 

Implementation Plan (SIP) revision.7 The purpose of this SIP revision is to demonstrate how the 

West Pinal County nonattainment area will attain the 1987 24-hour PM10 NAAQS. 

3.2 National Ambient Air Quality Standards 

Title I of the CAA requires the EPA to set National Ambient Air Quality Standards (NAAQS) for 

those pollutants that are considered harmful to both the public health and the environment. 

EPA sets standards for six air pollutants: ground-level ozone, particulate matter, carbon 

monoxide, nitrogen dioxide, sulfur dioxide, and lead. There are two types of NAAQS: primary 

and secondary. Primary standards are set to protect human health and secondary standards are 

established to protect public welfare, such as decreased visibility and damage to animals, crops, 

vegetation, and buildings.8

The standard for each pollutant is set at a maximum concentration in either parts per million 

(ppm) by volume, parts per billion (ppb) by volume, or micrograms per cubic meter of air 

(μ/m3). Each standard also has a distinct averaging time in order to provide the necessary level 

of protection.9 These standards are periodically reviewed and are either retained or revised 

based on review of scientific literature and analyses.10

7 See Arizona Revised Statutes (Ariz. Rev. Stat.) §49-406 (2015). 8 National Ambient Air Quality Standards, http://www.epa.gov/air/criteria.html (last visited Jun. 30, 2015). 9 Id. 10 See 42 U.S.C. § 7409 (2015).

December 21, 2015 Final 21

 
3.3 U.S. EPA's Particulate Matter NAAQS 

Particulate matter, or particle pollution, is a complex mixture of small particles and liquid 

droplets found in the air. Particulate matter (PM) can be directly emitted by a source such as 

smokestacks, fires, unpaved roads, or construction sites.11 These particles can also be formed in 

the atmosphere when gaseous pollutants such as sulfur dioxides and nitrogen dioxides react to 

form fine particles.12

On July 1, 1987, EPA revised the NAAQS for PM, replacing Total Suspended Particulates as the 

indicator for particulate matter with a new indicator, PM10..

13 This new indicator included 

particles with an aerodynamic diameter less than or equal to 10 micrometers. In order to attain 

the NAAQS for the 24-hour PM10 standard, an air quality monitor cannot measure levels of PM10

greater than 150 micrograms per cubic meter (μg/m3

) more than once per year on average over 

a consecutive three-year period.14 Table 3-1 provides a summary of the PM10 NAAQS for each 

of EPA’s review cycles from 1987 through 2012.15

Table 3-1 PM10 NAAQS History

Date Final Rule Citation Primary/ 

Secondary

Averaging 

Time Level Form

1987 52 Fed. Reg. 24634

Jul 1, 1987

Primary and 

Secondary

24-hour 150 μg/m3

Not to be exceeded more than 

once per year on average over a 

3-year period.

Annual 50 μg/m3 Annual arithmetic mean 

averaged over 3 years.

1997 62 Fed. Reg. 38652 

Jul 18, 1997

Primary and 

Secondary

24-hour 150 μg/m3

Not to be exceeded more than 

once per year on average over a 

3-year period.16

Annual17 50 μg/m3 Annual arithmetic mean 

averaged over 3 years.

2006 71 Fed. Reg. 61144 

Oct 17, 2006

Primary and 

Secondary 24-hour 150 μg/m3

Not to be exceeded more than 

once per year on average over a 

3-year period.

2012 78 Fed. Reg. 3086 Primary and 24-hour 150 μg/m3 Not to be exceeded more than 

11 See 42 U.S.C. § 7602(h) (2015). 12 Particulate Matter, http://www.epa.gov/airquality/particlepollution/ (last visited Jun. 30, 2015). 13 See generally, Revisions to Ambient Air Quality Standards for PM, 52 Fed. Reg. 24634 (Jul. 1, 1987) (codified at 

40 C.F.R. pt. 50).

14 As calculated rounding to the nearest 10 μg/m3, according to 40 C.F.R. § 50, Appendix K (2015) (effective 2006). 

For example, according to the rounding convention dictated by Appendix K, a value of 154 μg/m3 is rounded down 

to 150 μg/m3

. 15 The historical PM NAAQS also include “total suspended particulates” and PM2.5, neither of which is included in 

this summary. 

16 The form of the standard was initially promulgated as 99th percentile, averaged over 3 years; when the 1997 

standards were vacated, the form of the 1987 standards remained in place. See National Ambient Air Quality 

Standards for PM, 69 Fed. Reg. 45592 (Jul. 30, 2004) (codified at 40 C.F.R. pts. 50 and 58). 17 EPA revoked the annual PM10 NAAQS in 2006. See National Ambient Air Quality Standards for PM, 71 Fed. Reg. 

61144 (Oct. 17, 2006) (codified at 40 C.F.R. pt. 50).

December 21, 2015 Final 22

 
Jan. 15, 2013 Secondary once per year on average over a 

3-year period.

3.4 Regulatory Background

Most of Pinal County was designated as “unclassifiable” for PM10 by operation of law upon 

enactment of the 1990 CAA amendments. On October 14, 2009, EPA notified the Governor of 

Arizona and leaders of four Indian Tribes, whose lands are located entirely, or in part, within 

Pinal County, that air quality monitoring data for the period 2006 to 2008, revealed the area 

was violating the 24-hour PM10 NAAQS.18 EPA then began the process to redesignate the area 

as nonattainment for the 24-hour PM10 NAAQS. 

Under Section 107(d) of the CAA, governors must submit boundary recommendations for 

violating areas. ADEQ conducted a “nine factor” analysis based on the analytical approach 

established in EPA’s guidance for the 1997 8-hour ozone, the 1997 PM2.5 NAAQS, and the 2006 

PM2.5 NAAQS.19 ADEQ evaluated Pinal County as well as neighboring counties to determine 

what areas were violating or contributing to violations of the NAAQS. On March 23, 2010, the 

Governor of Arizona submitted to EPA nonattainment area boundary recommendations, 

excluding Tribal Lands.

20

On May 31, 2012, EPA redesignated an area in western Pinal County, Arizona, from 

“unclassifiable” to “nonattainment” for the 1987 PM10 NAAQS.21 The “West Pinal County PM10

Nonattainment Area” was classified as a “moderate area” under CAA § 188. The CAA imposes 

certain planning requirements for moderate nonattainment areas to reduce PM10 emissions 

and attain the NAAQS. On December 30, 2013, ADEQ submitted a revision to the Arizona SIP to 

meet certain CAA obligations for PM10 nonattainment areas (emissions inventory, ambient 

monitoring data, and base year modeling) and commitments to comply with additional 

requirements. Because the 2013 revision did not contain all required elements for 

nonattainment area SIP, ADEQ withdrew the plan from consideration for EPA action on 

February 19, 2014, in order to develop the remaining elements.

18 Letter from Laura Yoshii, Acting Regional Administrator, EPA Region IX to Governor Brewer of Arizona (Oct. 14, 

2009).

19 See Area Designations for the Revised 24-Hour Fine Particle National Ambient Air Quality Standards, 

memorandum to Regional Administrators, Regions I-X, from Robert J. Meyers, Acting Assistant Administrator, 

Office of Air and Radiation (June 8, 2007). 

20 Letter from Governor Brewer of Arizona to Jared Blumenfeld, Regional Administrator, EPA Region IX (Mar. 23, 

2010). 

21 Redesignation of West Pinal County as Nonattainment for PM10, 77 Fed. Reg. 32024 (May 31, 2012) (codified at 

40 C.F.R. pt. 81.303).

December 21, 2015 Final 23

 
3.5 West Pinal County PM10 Nonattainment Area Description

The following sections describe the boundary of the nonattainment area and provide 

information on the geography, climate, population, and economy of Pinal County and the PM10

planning area.

3.5.1 West Pinal County PM10 Nonattainment Area Boundary

The boundaries of the West Pinal County PM10 nonattainment area are defined at 40 C.F.R. § 

81.303. Figure 3-1 below maps the location of the area.

December 21, 2015 Final 24
Figure 3-1 Map of West Pinal County PM10 Nonattainment Area

Source: Arizona Department of Environmental Quality

December 21, 2015 Final 25
3.5.2 Geography and Climate

Pinal County is located in Central Arizona, lying within a basin between the Phoenix and Tucson 

metropolitan areas and encompasses approximately 5,365.61 square miles.

22 The eastern 

portion of the county is mountainous with elevations up to 6,441 feet,23 whereas the western 

region primarily consists of low desert valleys. The county includes several cities that are 

primarily located in low desert areas. Table 3-2 provides a list of incorporated cities and 

elevations that are located within Pinal County jurisdiction.

Table 3-2 Names and Elevations of West Pinal County Cities

City Name Elevation (ft.)

Apache Junction 1,754

Casa Grande 1,403

Coolidge 1,428

Eloy 1,555

Florence 1,473

Maricopa 1,171

Superior 2,842

Source: How High is Greater Phoenix?24

The climate is arid in the nonattainment area and the county in general. As a representative 

example, Casa Grande National Monument average monthly maximum temperatures range

from 66.0°F to 106.2°F, and the average monthly minimum temperatures range from 35.7°F to 

75.8°F.25 The driest time of the year for the County is typically April through June followed by 

September through November. Average monthly precipitation ranges from 0.061 up to 1.28 

inches. Figure 3-2 shows the annual average monthly temperatures and precipitation for the 

Casa Grande National Monument in Pinal County, Arizona. 

22 United States Census Bureau, Pinal County, Arizona QuickFacts Beta, 

http://quickfacts.census.gov/qfd/states/04/04021.html (last visited Jun. 29, 2015). 23 Report to Citizens for Fiscal Year 2011-2012, (Jun. 29, 2015) http://www.pinalcountyaz.gov/departments/mfr/

documents/reporttocitizens2011_12.pdf .

24 How High is Greater Phoenix, (Jun. 29, 2015) http://phoenix.about.com/od/natureandenvironment/a/elevation

_4.htm. 25 National Centers for Environmental Information, Data Tools: 1981-2010 – Casa Grande National Monument, 

Arizona (Jun. 29, 2015) http://www.ncdc.noaa.gov/cdo-web/datatools/normals. 

December 21, 2015 Final 26

 
 

Source: NOAA National Centers for Environmental Information – Data Tools26

3.5.3 Population

According to the Arizona Department of Administration (ADOA), the West Pinal PM10 

Nonattainment Area has a total population of 259,141 for the emissions inventory base year 

2008.27 Residence data shows that 136,790 of the population lived in the incorporated areas 

(Cities/Towns), 34,937 people lived in unincorporated (non-CDP) areas, and 87,414 lived within 

the Census Designated Places (CDP).28 Table 3-3 shows the population distribution for each 

area within the West Pinal County PM10 Nonattainment Area. 

26 Id. 27 Internal Report from the Arizona Department of Administration, October 31, 2013. 28 Census Designated Places (CDPs) are delineated for the decennial census. CDPs are places that are not legally 

incorporated and represent the statistical counterparts of incorporated places (e.g. cities/towns).

Figure 3-2 Casa Grande National Monument, Arizona, Monthly Average Temperatures and 

Precipitation: 1981-2010 Normals

December 21, 2015 Final 27

 
Table 3-3 West Pinal County PM10 Nonattainment Area Population Distribution – 2008 

Emissions Inventory Base Year

Place Population

Apache Junction City 4

Casa Grande City 48,096

Coolidge City 12,236

Eloy City 14,620

Florence Town 22,574

City of Maricopa 38,794

Queen Creek Town 467

Ak-Chin Village CDP 5

Arizona City CDP 9,781

Blackwater CDP 0

Cactus Forest CDP 555

Chuichu CDP 0

Gold Canyon CDP 11

Picacho CDP 440

Red Rock CDP 0

San Tan Valley CDP 75,932

Stanfield CDP 691

Total Population within the Nonattainment Area: 259,141

Source: Arizona Department of Administration - October, 2013, Internal Report

3.5.4 County Economy

The eastern portion of Pinal County is characterized as copper mining communities. The 

communities of Mammoth, Oracle, San Manuel, and Kearny have traditionally been active in 

copper mining, smelting, milling and refining. The towns of Apache Junction, Arizona City, 

Coolidge, Eloy, and particularly Casa Grande have expanded and diversified their economic base 

to include manufacturing, trade, and services.29 This expansion of the economy has been 

facilitated by the location of the area in the major growth corridor between Phoenix and 

Tucson and also by the growth of Mesa, near Apache Junction.30

Table 3-4 provides a percentage distribution of the total employed population by various 

sectors. Total civilian employed population has increased by 3.7% since 2010.31

29 Pinal County Statistics (Jun. 29, 2015), http://www.pinalcountyaz.gov/ed/businessconnections/Pages/

PinalCountyStatistics.aspx. 30 Id. 31 U.S. Census Bureau, American FactFinder – Selected Economic Characteristics (Jun. 29, 2015), 

http://factfinder.census.gov/faces/tableservices/jsf/pages/productview.xhtml (deduced from comparing 2010 to 

2013 for Pinal County, AZ).

December 21, 2015 Final 28

 
Table 3-4 Pinal County Civilian Employed Population 16 Years and Over – 2013 U.S. Census 

Bureau

Industry Population Percentage

Agriculture, forestry, fishing and hunting, and mining 5,290 3.8%

Construction 8,708 6.3%

Manufacturing 13,831 10.0%

Wholesale trade 2,010 1.5%

Retail trade 18,433 13.4%

Transportation and warehousing, and utilities 5,934 4.3%

Information 3,424 2.5%

Finance and insurance, and real estate and rental and 

leasing 8,659 6.3%

Professional, scientific, and management, and 

administrative and waste management services 10,817 7.9%

Educational services, and health care and social 

assistance 27,015 19.6%

Arts, entertainment, and recreation, and 

accommodation and food services 16,068 11.7%

Other services, except public administration 6,103 4.4%

Public administration 11,470 8.3%

Total Civilian Employed Population 137,762 100.0%

Source: U.S. Census Bureau, 2013. American Community Survey32

The median household income in Pinal County was $49,756 in 2013. The median household 

income decreased by just 0.07% from 2010 to 2013, while the mean increased by 5.65% during 

the same timeframe.33

In 2008, the number of permits issued for residential buildings and units were 3,016 and 3,020, 

respectively.34 By 2014, the number of reported permits issued for buildings and units issued 

decreased to 1,729 and 1,744, respectively.35 Table 3-5 provides a four-year annual summary of 

the issued building permits in Pinal County.

32 Id. 33 Id. 34 Building Permits, U.S. Census of Bureau, http://censtats.census.gov/bldg/bldgprmt.shtml? (last visited Jun. 15, 

2015).

35 Id.

December 21, 2015 Final 29

 
Table 3-5 Annual New Privately-Owned Residential Building Permits

Year Buildings Units Cost

2014 1,729 1,744 $318,720,727

2013 2,129 2,144 $344,388,193

2012 1,776 1,823 $244,641,995

2011 975 978 $126,271,132

2010 1,597 1,597 $206,850,342

2009 2,182 2,182 $284,576,575

2008 3,016 3,020 $370,613,362

Source: Building Permits - U.S. Census Bureau36

3.6 General SIP Approach - Regulatory Requirements and 

Guidance

In November 1990, the U.S. Congress enacted a series of amendments to the CAA. One of the 

primary effects of the revision was to expand and clarify the planning provisions for those areas 

not meeting the NAAQS. The CAA, as amended, authorizes comprehensive federal and state 

programs to provide for attainment and maintenance of the NAAQS. Section 3.6.1 outlines CAA 

requirements for moderate PM10 nonattainment areas. In addition, EPA has published guidance 

documents to clarify environmental regulations relating to attainment of the NAAQS and to 

assist in developing approaches for implementing those regulations. Section 3.6.2 summarizes 

applicable EPA guidance.

3.6.1 Clean Air Act Requirements for Nonattainment Area Plans

The 1990 CAA amendments identify specific emission reduction goals, require both a 

demonstration of Reasonable Further Progress (RFP) and attainment, and incorporate more 

stringent sanctions for failure to attain or to meet interim milestones. CAA Title I Part A, and 

Title I Part D, Subparts 1 and 4 are applicable to PM10 plans. Table 3-6 lists the CAA 

requirements and explains how the demonstrations contained in this document satisfy those 

obligations. Pollutant specific requirements for moderate PM10 nonattainment areas are found 

in §§ 188 through 190 of the CAA, and the general planning and control requirements for 

nonattainment area plans are found in CAA §§ 110 and 172. 

36 Id.

December 21, 2015 Final 30

 
Table 3-6 Clean Air Act (CAA) Requirements for Moderate PM10 Nonattainment Area SIPs

CAA Citation Action to Meet Requirement Location in 

Document

CAA Title I – Air Pollution Prevention and Control; Part A – Air Quality and Emissions Limitations;

Section 110 – Implementation Plans

110(a)(2)(A) Requires that implementation plans “include enforceable 

emission limitations and other control measures, means, or 

techniques (including economic incentives such as fees, 

marketable permits, and auctions of emissions rights), as well as 

schedules and timetables for compliance, as may be necessary or 

appropriate to meet the applicable requirements of this 

chapter.”

Chapter 6 describes the measures implemented to reduce PM10

emissions and ensure future attainment of the NAAQS. 

Chapter 6.

CAA Title I – Air Pollution Prevention and Control; Part D – Plan Requirements for Nonattainment 

Areas;

Subpart 1 – Nonattainment Areas in General; Section 172. Nonattainment Plan Provisions in 

General;

Subsection 172(c) Nonattainment Plan Provisions

§ 172(c)(1) – In 

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 6 contains an explanation of applicable RACM for PM10

sources in the nonattainment area. Chapter 7demonstrates the 

area will attain the air quality standards with all implemented 

controls.

Chapter 6 and 

Chapter 7. 

§ 172(c)(2) – RFP 

[Reasonable 

Further Progress]

“Such plan provisions shall require reasonable further progress” 

defined in CAA Sec. 171(1) as “... annual incremental reductions in 

emissions ... for the purpose of ensuring attainment of the 

applicable national ambient air quality standards by the 

applicable date.”

This submittal demonstrates, in accordance with EPA Guidance, 

that the West Pinal County Nonattainment Area will achieve 

required emissions reductions within the required timeframes 

necessary to attain the PM10 NAAQS. As such, the RFP 

Chapter 6 and 

Appendix D 

(Attainment 

TSD).

December 21, 2015 Final 31
CAA Citation Action to Meet Requirement Location in 

Document

requirement is met. Chapter 7 contains emissions projections 

after application of control strategies. Chapter 6 includes an 

explanation of measures responsible for the emissions 

reductions and implementation schedules for each rule. 

§ 172(c)(3) –

Inventory 

[Emissions]

“Such plan provisions shall include a comprehensive, accurate, 

current inventory of actual emissions from all sources of the 

relevant pollutant or pollutants in such area, including such 

periodic revisions as the Administrator may determine necessary 

to assure that the requirements of this part are met.”

ADEQ maintains a historical and current database of actual 

emissions from State permitted point and area sources. The 

Pinal County Air Quality Control District maintains a similar 

database of actual emissions from County permitted sources. All 

non permitted source emissions data (i.e.: area and mobile 

sources) were developed for this plan. Base-year and projected 

base emissions are contained in Chapter 5.

Chapter 5 and 

Appendix B (EI 

TSD).

§ 172(c)(4) –

Identification 

and 

Quantification

“Such plan provisions shall expressly identify and quantify the 

emissions, if any, of any such pollutant or pollutants which will be 

allowed, in accordance with Section 173(a)(1)(B), from the 

construction and operation of major new or modified stationary 

sources in each such area. The plan shall demonstrate to the 

satisfaction of the Administrator that the emissions quantified for 

this purpose will be consistent with the achievement of 

reasonable further progress and will not interfere with 

attainment of the applicable national ambient air quality 

standard by the applicable attainment date.” 

The permit program requirements of CAA Section 173(a)(1)(B) 

are applicable to sources located in a “targeted economic 

development zone” as determined by the Administrator under 

consultation with the Secretary of Housing and Urban 

Development. No such zones are currently known to exist within 

the West Pinal Nonattainment Area. 

No additional 

location in 

document.

§ 172(c)(5) –

Permits for New 

and Modified 

Major Stationary 

Sources

“Such plan provisions shall require permits for the construction 

and operation of new or modified major stationary sources 

anywhere in the nonattainment area, in accordance with section 

173.”

Arizona Revised Statutes Title 49, Chapter 3, Articles 1, 2, and 3 

No additional 

location in 

document. 

December 21, 2015 Final 32
CAA Citation Action to Meet Requirement Location in 

Document

establish ADEQ and local agency authority for preconstruction 

review and permitting. Under the air permits program, sources 

that emit regulated pollutants are required to obtain a permit 

before constructing, changing, replacing, or operating any 

equipment or process which may cause air pollution. This 

includes equipment designed to reduce air pollution. Permits are 

also required if an existing facility that causes air pollution 

transfers ownership, relocates, or otherwise changes operations. 

Per the authority noted above, all new sources and modifications 

to existing sources in Arizona are subject to state requirements 

for preconstruction review and permitting under Arizona 

Administrative Code (AAC), Title 18, Chapter 2, Articles 2, 3, 4, 

and 5 or relevant county rules. All new major sources and major 

modifications to existing major sources in Arizona are also 

subject to the nonattainment New Source Review (NSR) 

provisions of these rules or Prevention of Significant 

Deterioration (PSD) for attainment areas. Sources under Pinal 

County jurisdiction are subject to the Pinal County Air Quality 

Control District, NSR program in Pinal County Code of 

Regulations, Chapter 3, Permits and Permit Revisions. 

ADEQ submitted a revision to the SIP on October 29, 2012, to 

update its program to comply with all current federal NSR 

requirements, including NSR reform. On June 29, 2015, EPA 

signed a limited approval/limited disapproval (LA/LD) of this SIP 

revision. ADEQ is under an obligation to correct the deficiencies 

identified by EPA. Until the corrections are approved, however, 

the rules subject to the LA/LD will be part of the SIP.

Pinal County has a SIP-approved PSD program but lacks any form 

of EPA approval for nonattainment NSR. ADEQ therefore has 

original jurisdiction over major sources in Pinal County, but has 

delegated that jurisdiction to the County under A.R.S. § 49-107.

§ 172(c)(6) –

Other Measures

“Such plan provisions 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 

specified in this part.”

Chapter 6 and 

Chapter 7.

December 21, 2015 Final 33
CAA Citation Action to Meet Requirement Location in 

Document

Consistent with CAA requirements and EPA Guidance, this 

submittal includes emissions limitations, control strategies, and 

applicable compliance schedules for PM10 sources in the 

nonattainment area. Air quality modeling demonstrates that the 

area will attain the PM10 NAAQS with control measures fully 

implemented. 

§ 172(c)(7) –

Compliance with 

Section 110(a)(2)

“Such 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.

No additional 

location in 

document.

§ 172(c)(8) –

Equivalent 

Techniques

“Upon application by any State, the Administrator may allow the 

use of equivalent modeling, emission inventory, and planning 

procedures, unless the Administrator determines that the 

proposed techniques are, in the aggregate, less effective than the 

methods specified by the Administrator.”

ADEQ’s intended modeling and emissions inventory 

methodologies (Inventory Preparation Plan) were submitted to 

and reviewed by EPA. Some modifications to the intended 

methodologies were required to make the plan more 

scientifically sound. The analyses to establish emissions limits 

and control strategies were conducted using AERMOD and 

modified rollback modeling with EPA’s concurrence. 

Chapter 7, 

Chapter 5, 

Appendix B (EI 

TSD), 

Appendix C

(Modeling 

TSD), and 

Appendix D 

(Attainment 

TSD).

§ 172(c)(9) –

Contingency 

Measures

“Such plan shall provide for the implementation of specific 

measures to be undertaken if the area fails to make reasonable 

further progress, or to attain the national primary ambient air 

quality standard by the attainment date applicable under this 

part. 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.”

Consistent with EPA guidance, this submittal includes measures 

(beyond what is necessary to demonstrate attainment) to 

provide for emissions reductions equivalent to one year’s 

average increment of RFP. As such, the contingency measure 

requirement is met.

Chapter 6 and 

Appendix D 

(Attainment 

TSD).

December 21, 2015 Final 34
CAA Citation Action to Meet Requirement Location in 

Document

CAA Title I – Air Pollution Prevention and Control; Part D – Plan Requirements for Nonattainment 

Areas;

Subpart 1 – Nonattainment Areas in General; Section 176. Limitations on Certain Federal 

Assistance

§ 176(c) –

[Transportation 

Conformity]

Transportation conformity is required under Clean Air Act section 

176(c) [42 U.S.C. 7506(c)] to ensure that federal funding and 

approval are given to highway and transit projects that are 

consistent with ("conform to") the air quality goals established by 

the state air quality implementation plan (SIP). Conformity, to 

the purpose of the SIP, means that proposed transportation 

activities will not: 1) cause new air quality violations, 2) worsen 

existing violations, or 3) delay timely attainment of the national 

ambient air quality standards (including any required interim 

emission reductions or milestones).37 

The conformity rules at 40 CFR Parts 51.390 and 93 require the 

SIP to include maximum allowable emissions or a “budget” for 

on-road mobile sources. Projected emissions from future 

transportation projects are compared to the approved budget to 

ensure they do not exceed levels demonstrated necessary to 

attain and maintain the NAAQS.

Discussion of transportation conformity and on-road motor 

vehicle emissions budgets for the West Pinal PM10 planning area 

are included in Chapter 5.

Chapter 5, 

Section 5.5.

§ 176(c) –

[General 

Conformity]

Similar to Transportation Conformity, which applies to highways 

and mass transit projects, General Conformity is applicable to all 

other federally supported activities to ensure that the actions 

taken by federal agencies in nonattainment and maintenance 

areas do not interfere with a state’s plans to meet national air 

quality standards. 

General Conformity for the West Pinal County Nonattainment 

Area must be addressed to assure PM10 emissions from any 

federal actions or plans do not exceed the rates outlined in 40 

CFR 93.153(b) (see 58 FR 63253; November 30, 1993). Criteria 

for making determinations and provisions for general conformity 

No other 

location in 

document.

37 State and Local Transportation Resources (Jun. 29, 2015), http://www.epa.gov/OMS/stateresources/transconf/ 

generalinfo.htm.

December 21, 2015 Final 35

 
CAA Citation Action to Meet Requirement Location in 

Document

are located in R18-2-1438 of the Arizona Administrative Code. 

ADEQ and Pinal County commit to review and comment, as 

appropriate, on any federal agency draft general conformity 

determination it receives pursuant to 40 CFR 93.155 for activities 

planned for this air quality planning area.

CAA Title I – Air Pollution Prevention and Control; Part D – Plan Requirements for Nonattainment 

Areas;

Subpart 4 – Additional Provisions for Particulate Matter Nonattainment Areas; 

Section 188. Classifications and Attainment Dates, Section 189. Plan Provisions and Schedules for 

Plan Submissions, and Section 190. Issuance of RACM and BACM Guidance

§ 188(c)(1) –

Attainment 

Dates

“For a Moderate Area, the attainment date shall be as 

expeditiously as practicable but no later than the end of the sixth 

calendar year after the area’s designation as nonattainment, 

except that, for areas designated nonattainment for PM–10 

under section 107(d)(4), the attainment date shall not extend 

beyond December 31, 1994.”

A portion of West Pinal County was redesignated as a “moderate’ 

nonattainment area effective July 2, 2012. The area is required 

to demonstrate attainment no later than the end of December 

2018. 

Chapter 7.

§ 188(d) –

Extension of 

Attainment Date 

for Moderate 

Areas

“Upon application by any State, the Administrator may extend for 

1 additional year (hereinafter referred to as the “Extension Year”) 

the date specified in paragraph (c)(1) if– (1) the State has 

complied with all requirements and commitments pertaining to 

the area in the applicable implementation plan; and (2) no more 

than one exceedance of the 24-hour national ambient air quality 

standard level for PM–10 has occurred in the area in the year 

preceding the Extension Year, and the annual mean 

concentration of PM10 in the area for such year is less than or 

equal to the standard level. No more than 2 one-year extensions 

may be issued under the subsection for a single nonattainment 

area.”

ADEQ is not requesting an extension at this time.

No other 

location in 

document.

December 21, 2015 Final 36
CAA Citation Action to Meet Requirement Location in 

Document

§ 189(a)(1)(A) –

Moderate Areas, 

Plan Provisions

“For the purpose of meeting the requirements of section 

7502(c)(5)..., a permit program providing that permits meeting 

the requirements of section 7503 are required for the 

construction and operation of new and modified major stationary 

sources of PM–10.”

The State and Pinal County permitting programs are described at 

“172(c)(5) – Permits for New and Modified Major Stationary 

Sources” of this table.

No other 

location in 

document.

§ 189(a)(1)(B) –

Moderate Areas, 

Plan Provisions

“Either: (i) a demonstration (including air quality modeling) that 

the plan will provide for attainment by the applicable attainment 

date; or (ii) a demonstration that attainment by such date is 

impracticable.”

Attainment of the NAAQS is demonstrated through the use of 

AERMOD and modified rollback modeling.

Chapter 7 and 

Appendix D 

(Attainment 

TSD).

§ 189(a)(1)(C) –

Moderate Areas, 

Plan Provisions

“Provisions to assure that reasonably available control measures 

for the control of PM–10 shall be implemented no later than 

December 10, 1993, or 4 years after designation in the case of an 

area classified as moderate after the date of the enactment of 

the Clean Air Act Amendments of 1990 [November 15, 1990].”

Implementation schedules for the West Pinal County reasonably 

available control measures are included in Chapter 6. 

Chapter 6. 

§ 189(a)(2)(B) –

Moderate Areas, 

Schedule for 

Plan Submissions

“18 months after the designation as nonattainment ...”

This SIP replaces a plan originally submitted on December 30, 

2013, a submittal that was later withdrawn.

No other 

location in 

document.

§ 189(c)(1) –

Milestones

“Plan revisions demonstrating attainment submitted to the 

Administrator for approval under this subpart shall contain 

quantitative milestones which are to be achieved every 3 years 

until the area is redesignated attainment and which demonstrate 

reasonable further progress, as defined in section 171(1), toward 

attainment by the applicable date.”

Emissions reduction milestones are included in Chapter 7.

Chapter 7. 

December 21, 2015 Final 37
CAA Citation Action to Meet Requirement Location in 

Document

§ 189(c)(2) –

Milestones

“Not later than 90 days after the date on which a milestone 

applicable to the area occurs, each State in which all or part of 

such area is located shall submit to the Administrator a 

demonstration that all measures in the plan approved under this 

section have been implemented and that the milestone has been 

met. A demonstration under this subsection shall be submitted in 

such form and manner, and shall contain such information and 

analysis, as the Administrator shall require. The Administrator 

shall determine whether or not a State’s demonstration under 

this subsection is adequate within 90 days after the 

Administrator’s receipt of a demonstration which contains the 

information and analysis required by the Administrator.”

ADEQ commits to submit all required demonstrations.

No other 

location in 

document.

§ 189(c)(3) –

Milestones

“If a State fails to submit a demonstration under paragraph (2) 

with respect to a milestone within the required period or if the 

Administrator determines that the area has not met any 

applicable milestone, the Administrator shall require the State, 

within 9 months after such failure or determination to submit a 

plan revision that assures that the State will achieve the next 

milestone (or attain the national ambient air quality standard for 

PM–10, if there is no next milestone) by the applicable date.” 

ADEQ commits to submit all required demonstrations.

No other 

location in 

document.

§ 189(e) –PM–10 

Precursors

“The control requirements applicable under plans in effect under 

this part for major stationary sources of PM–10 shall also apply 

to major stationary sources of PM–10 precursors, except where 

the Administrator determines that such sources do not contribute 

significantly to PM–10 levels which exceed the standard in the 

area. The Administrator shall issue guidelines regarding the 

application of the preceding sentence.”

ADEQ determined that emissions of PM10 precursors do not 

contribute significantly to exceedances of the NAAQS in the West 

Pinal Nonattainment Area. See Appendix B (EI TSD), Exhibit 16

(Precursor Emission Summary) for details of the analysis.

Appendix B (EI 

TSD), Exhibit 

16 (Precursor 

Emission 

Summary)

§ 190 – Issuance 

of RACM and 

BACM Guidance

“The Administrator shall issue, in the same manner and according 

to the same procedure as guidance is issued under section 108(c), 

technical guidance on reasonably available control measures and 

best available control measures for urban fugitive dust, and 

emissions from residential wood combustion...”

Chapter 3, 

Section 3.6.2

December 21, 2015 Final 38
CAA Citation Action to Meet Requirement Location in 

Document

ADEQ employed appropriate EPA guidance in the development 

of this plan.

3.6.2 EPA Guidance

The guidance documents utilized in the preparation of this plan include:

• Emissions Inventory Guidance for Implementation of Ozone and Particulate Matter 

National Ambient Air Quality Standards (NAAQS) and Regional Haze Regulations. U.S. 

Environmental Protection Agency. EPA-454/R-05-001. August 2005.

• PM10 SIP Development Guideline. U.S. Environmental Protection Agency. EPA-450/2-86-

001. June 1987.

• PM-10 Guideline Document. U.S. Environmental Protection Agency. EPA-452/R-93-008. 

April 1993.

• State Implementation Plans; General Preamble for the Implementation of Title I of the 

Clean Air Act Amendments of 1990. U.S. Environmental Protection Agency. 57 Federal 

Register 13498; April 16, 1992.

• State Implementation Plans; General Preamble for the Implementation of Title I of the 

Clean Air Act Amendments of 1990; Supplemental. U.S. Environmental Protection 

Agency. 57 Federal Register 18070; April 28, 1992.

• 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. 

U.S. Environmental Protection Agency. 59 Federal Register 41998; August 16, 1994.

December 21, 2015 Final 39
(This page is intentionally blank.)

December 21, 2015 Final 40
4 AMBIENT AIR QUALITY MONITORING

The primary goal of the PM10 monitoring network in Pinal County is to collect ambient data 

necessary to determine compliance with the PM10 NAAQS and fulfill the regulatory 

requirements for PM10 monitoring in the nonattainment area. 

This chapter provides a general description of the monitoring sites, equipment, a historic data 

summary, and current 24-hour NAAQS compliance in the West Pinal PM10 Nonattainment Area. 

4.1 Monitoring Site, Equipment, and Quality Assurance 

Procedures

Arizona’s air monitoring network consists of state and local stations operated according to the 

requirements of 40 CFR Part 58. Collected data are quality assured and reported to EPA’s Air 

Quality System (AQS) for comparison to the NAAQS. Pinal County maintains authority to 

conduct ambient surveillance under ARS § 49-473 and Pinal County Code, Section 1-1-040. In 

February of 2013, ADEQ and PCAQCD entered into a memorandum of agreement to clarify and 

define the responsibilities of a Primary Quality Assurance Organization (PQAO).38

Pinal County uses Federal Reference Method (FRM) monitors to collect filter based PM10 and 

automated Federal Equivalent Method (FEM) monitors for recording continuous PM10. 

Historically three types of PM10 monitors have been used throughout the Pinal County 

monitoring network: (1) filter-based, high-volume samplers, (2) filter based, medium-volume 

samplers, and (3) Tapered Element Oscillating Microbalance (TEOM) monitors which measure 

PM10 on a continuous basis. Currently 8 monitors are in operation in the West Pinal County 

PM10 planning area; 6 continuous and 2 filter based medium-volume units with periodic 

sampling.39 Several of the TEOM sites have also operated filter monitors prior to installation of 

continuous monitoring.

The installed monitors are maintained in accordance with federal siting and design criteria40

and are consistent with the Pinal County Air Quality Control District, 2014 Ambient Monitoring 

Network Plan and 2013 Data Summary, approved by EPA for the West Pinal area on October 

29, 2014.

Figure 4-1 maps the locations of monitoring sites located within the West Pinal Nonattainment 

Area. Table 4-1 provides site descriptions for these monitors.

38 Memorandum of Agreement No. ADEQ 13-033141(Feb. 13, 2013), available at http://agendasearch.pinalcounty 

az. gov/AttachmentViewer.aspx?AttachmentID=14187&ItemID=9048. 

39 There are no longer any high-volume samplers in the West Pinal PM10 Nonattainment Area; however, data from 

past measurements are still used to calculate design values for comparison to the NAAQS.

40 Network Design Criteria for Ambient Air Quality Monitoring are located in 40 C.F.R. Part 58, Appendix D. Probe 

and Monitoring Path Siting Criteria for Ambient Air Quality Monitoring are found in 40 C.F.R. Part 58, Appendix A.

December 21, 2015 Final 41

 
Figure 4-1 West Pinal County PM10 Nonattainment Area

Source: Arizona Department of Environmental Quality

December 21, 2015 Final 42
Table 4-1 Active Monitors within the West Pinal County PM10 Nonattainment Area

AQS ID Site Name Latitude Longitude Classification

41

Monitor 

Type

Street 

Address City

04-021-

0001

Casa Grande 

Downtown +32.877583 -111.752222 SLAMS TEOM 401 N Marshall St. Casa Grande

04-021-

3009 Combs School +33.219111 -111.561111 SLAMS TEOM 301 E Combs Rd Queen Creek

04-021-

3004

Coolidge 

Maintenance Yard +32.978556 -111.514833 SLAMS

MediumVolume

42

212 E 

Broadway Coolidge

04-021-

3013 Cowtown Road +33.010530 -111.972050 SPM43 TEOM 37580 W Maricopa Maricopa

04-021-

3014 Eloy County Complex +32.757639 -111.554861 SLAMS

MediumVolume

44

801 N Main 

St Eloy

04-021-

3010

Maricopa County 

Complex (City of 

Maricopa)

+33.010530 -

111.972050 SLAMS TEOM 44625 W Garvey Rd Maricopa

04-021- Pinal County Housing +32.891056 - SLAMS TEOM 970 N 11 Casa Grande

41 SLAMS is defined at 40 C.F.R. 58.1 as a “State or local air monitoring stations(s).” Data from SLAMS sites are primarily used for comparison to the NAAQS. 

SPM or Special Purpose Monitors are generally monitors established for use in special studies and are not used to show compliance with minimum network 

requirements in 40 C.F.R. 58 (e.g. number and siting of monitors).

42 The 2014 Pinal County Network Plan identifies collocated medium-volume PM10 samplers at the Coolidge Maintenance Yard effective July 1, 2013. The 

samplers operate (collect data) on a one in six-day schedule. Prior to this date, a high volume sampler was operated at this site. 43 The Cowtown monitor is currently designated as a special purpose monitor (SPM). During its review of the 2012 Pinal County Network Plan, EPA commented 

that because the site has been active for longer than 24 months [and can be used for comparison to the NAAQS] it should be designated as a SLAMS monitor. 

Pinal County proposed to retain the SPM designation pending completion of a relocation process currently underway. See the Pinal County Air Quality Control 

District, 2014 Ambient Monitoring Network Plan and 2013 Data Summary for more information. 44 The 2014 Pinal County Network Plan identifies a single medium-volume PM10 sampler at the Eloy County Complex effective July 1, 2013. The sampler 

operates (collects data) on a one in six-day schedule. Prior to this date, a high volume sampler was operated at this site.

December 21, 2015 Final 43

 
AQS ID Site Name Latitude Longitude Classification

41

Monitor 

Type

Street 

Address City

3011 Complex 111.570500 Mile Rd

04-021-

3008

Stanfield County 

Complex +32.881194 -111.962000 SLAMS TEOM 36697 W Papago Rd Stanfield

Source: US EPA Site Description Report - May 7, 2013; updated May 2015 based on Pinal County’s 2014 Ambient Monitoring Network Plan.

December 21, 2015 Final 44
4.2 Historical PM10 Data Summary

EPA defines an “exceedance” as a discrete event, where a measured value at a monitor is 

higher than the level of the standard. The standard is attained when the expected number of 

days per calendar year with a 24-hour average concentration above 150 μg/m3 is equal to or 

less than one. The number of expected exceedances at a site is determined by recording the 

number of exceedances in each calendar year and then averaging them over the most recent 3 

year period.

45 

Non-continuous filter based samplers operate on a schedule based on the level of that 

monitoring site’s ambient concentrations relative to the 24-hour standard. The required 

sampling schedule can range from every day to a minimum of once every sixth day. Because 

some monitoring locations do not record a value for each day of the year, an adjustment is

made to the data collected to estimate the number of exceedances for that calendar year. To 

make the adjustment, it is assumed that the fraction of missing values (un-sampled days) that 

would have exceeded the level of the standard is identical to the fraction of measured values 

above this level. For example, one exceedance recorded by a one in six day monitor would 

count as 6.1 exceedances for that calendar year.46

Figure 4-2 shows the three-year average expected rate of exceedance for the current West 

Pinal monitoring network for years 2006 through 2014. The values presented from the 

Coolidge and Eloy monitoring sites are results from filter based PM10 samplers which collect 

samples on a one in six-day schedule. The six other monitoring sites, Casa Grande Downtown, 

Combs, Cowtown, Maricopa, Pinal County Housing, and Stanfield represent continuous data 

that were processed by PM10 TEOM air monitoring instrumentation. 

45 24-hour values as calculated rounding to the nearest 10 μg/m3

, according to 40 C.F.R. § 50, Appendix K (2015) 

(effective 2006).

46 See National primary and secondary ambient air quality standards for PM10, 40 C.F.R. § 50.6; Interpretation of 

the National Ambient Air Quality Standards for Particulate Matter, 40 C.F.R. § 50, Appendix K (2015) (effective 

2006).

December 21, 2015 Final 45

 
Figure 4-2 Three-Year Average Expected Rate of Exceedance

Source: U.S. EPA Air Quality System47

4.3 24-Hours PM10 NAAQS Compliance - 2012-2014

As noted above, the 24-hour PM10 standard is met when the expected number of exceedances 

per year at each monitoring site is less than or equal to one on average over a three year 

period. Based on complete quality-assured data for 2012-2014, the West Pinal County area is 

not currently meeting the PM10 NAAQS. The findings indicate that all six monitoring stations 

that use continuous PM10 TEOM samplers yielded a three-year average expected rate of 

exceedance greater than one. The monitoring station at Cowtown recorded the highest threeyear average expected rate of exceedance at 64 followed by the Stanfield monitor, which has a 

three-year average exceedance rate of 13. The filter based monitors at Coolidge and Eloy 

recorded no violations of the NAAQS.

47 2005-2014 Preliminary Design Value Report obtained on May 13, 2015. Data excludes regional (exceptional) 

events concurred by EPA.

79.3

142.7

201.2

139.8

86.1

60.7

63.0

75.7

64

0

15

30

45

60

75

90

105

120

135

150

165

180

195

210

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Three-Year Average Expected Rate of Exceedance

Year

Casa Grande Downtown

Combs School

Cowtown Road

Marciopa County Complex

Pinal County Housing Complex

Stanfield County Complex

Coolidge Maintence Yard

Eloy County Complex

December 21, 2015 Final 46

 
Table 4-2 below includes a summary of the most recent three-year average expected rate of 

exceedance for each of the West Pinal monitors. 

Table 4-2 2012 to 2014 Maximum 24-Hour Average PM10 Compliance

AQS ID Site Name

2012 2013 2014

Three-Year 

Avg Exp. 

Rate of Exc.

Max

24-Hr

Avg

Exp.

Exc.

Max

24-Hr

Avg

Exp.

Exc.

Max24-Hr

Avg

Exp.

Exc.

04-021-

0001

Casa Grande 

Downtown 235 2 301 4 929 5 4

04-021-

3009 Combs 205 5.1 299 3 247 5 4

04-021-

3004 Coolidge 134 0 139 0 109 0 0

04-021-

3013 Cowtown 698 60.7 1006 67.5 540 63.9 64.0

04-021-

3014 Eloy 120 0 107 0 80 0 0

04-021-

3010

City of 

Maricopa 

Complex (City 

of Maricopa)

256 8.6 333 4 238 2 5

04-021-

3011

Pinal County 

Housing 541 5 241 5.1 402 6.1 5

04-021-

3008 Stanfield 339 12.1 912 17 342 9.2 13

Exp. – Expected. Exc. – Exceedance.

Source: U.S. EPA Air Quality System48

48 AMP 450 report (Quick Look Criteria Parameters) and AMP 480 report (Design Value Report) dated July 23, 2015.

December 21, 2015 Final 47

 
5 ANNUAL EMISSIONS INVENTORY

This section addresses the requirement to develop an annual baseline emissions inventory for 

the entire PM10 nonattainment area, whereas the attainment modeling summary in Chapter 7

addresses the design day input inventories specific to each monitor. 

Section 172(c)(3) of the CAA requires that the base year inventory be a comprehensive, 

accurate, and current inventory of actual emissions in the nonattainment area. An annual 

emissions inventory helps identify which sources and source categories predominate in the 

generation of PM10 emissions across the nonattainment area. This ranking of source 

significance provides the basis for analysis of long-term emission trends impacted by changes in 

source activity rates and implementation of regulatory control strategies.

Through discussions between U.S. EPA, the Arizona Department of Environmental Quality 

(ADEQ), and the Pinal County Air Quality Control District (PCAQCD), a base year of 2008 was 

selected for the preparation of an emission inventory and an attainment demonstration. During 

2008, exceedances of the 24-hour PM2.5 NAAQS were recorded at Cowtown; exceedances of 

the 24-hour PM10 NAAQS were recorded at Maricopa, Cowtown, Stanfield, Casa Grande, 

Combs School, and Pinal County Housing.49 Therefore, inventory calculations were based on 

affects on these monitors. Precursor emissions are discussed further in the precursor emission 

summary discussion located in Exhibit 16 of Appendix B, Emission Inventory Technical Support 

Document.

5.1 Meteorological Scenarios and General Methodology

Inventory analysis showed that two scenarios produce emissions and contribute to 

concentrations in excess of the 24-hour PM10 National Ambient Air Quality Standard (NAAQS) of 

150μg/m3: windblown generation and activity-based generation. Separate and distinct sources 

contribute to each of the two emission generating scenarios, although there is some overlap 

between the sources. Therefore, ADEQ developed two different inventories for each base year 

to sum the total annual emissions.

During wind conditions 12 mph or higher, sources with disturbed soil spread a large proportion 

of the emissions throughout the nonattainment area (e.g. unpaved roads, fallow fields, etc.). 

Some source categorical activities release PM10 with or without wind because of their dust 

generating nature (e.g. earthmoving activities during construction and agricultural operations 

or driving on unpaved roads).

The spatial distribution of estimated PM10 emissions within the nonattainment area was 

facilitated by GIS shapefiles produced by PCAQCD and ADEQ. Shapefiles for population were 

49 Appendix A (Inventory Preparation Plan) A1-A2.

December 21, 2015 Final 48

 
provided by Arizona Department of Administration. MAG provided paved road and on-road 

emission information. Sierra Research modeled nonroad emissions using EPA model default

data for Pinal County. For other source categories (e.g., construction, confined animal feeding 

operations (CAFO), and railroads), emission estimates are based on activity rates of sources 

within the nonattainment area and emissions factors representative of these sources.50 Where 

appropriate, local precipitation event data were factored into the annual fugitive dust 

emissions calculations according to EPA guidance (e.g., such as reported for paved and unpaved 

road emissions in AP-4251).52 

5.2 Windblown Methodologies for the Base Years 2008 and 

2018

5.2.1 Annual Windblown Methodologies

Windblown emissions were calculated using a modified version of the methodology described

in the Maricopa Association of Governments’ (MAG’s) 2012 5% Plan, as a function of land use 

disturbance ratios and wind speed.

53 ADEQ determined adoption of the MAG windblown dust 

methodology as the most appropriate EPA approved windblown dust emission estimation 

methodology available. This is due to the similar meteorological characteristics of these 

neighboring counties and to provide consistency between the emission estimates for these two 

abutting PM10 nonattainment areas. Generally, the annual emissions are a summed function of 

the following actions:54

(a) each parcel in the nonattainment area was assigned a land use category with a distinct 

stable to disturbed land ratio, 

(b) individual parcels were assigned the meteorological characteristics (i.e. wind speed and 

precipitation) of the closest nonattainment area monitor, 

(c) friction velocities were calculated for hourly binned wind speeds, 

(d) friction velocities were then converted to wind speed dependent emission rates for 

disturbed and stable lands, 

(e) high wind event emission rates were adjusted to account for temporal variability in particle 

saltation and reservoir depletion, and finally 

50 See Appendix B (EI TSD) Section 5 Introduction. 51 Compilation of Air Pollutant Emissions Factors, AP-42, U.S. EPA, http://www.epa.gov/ttn/chief/ap42/index.html

(last visited July 29, 2013).

52 See Appendix B (EI TSD) Section 5. 53 See Appendix B (EI TSD) Section 3.1.2. 54 For an example calculation for windblown dust calculations specific to modeling design day calculations, but 

similar to this methodology, please see Chapter 7 Section 7.1.2.4. 

December 21, 2015 Final 49

 
(f) individual wind event emissions were calculated based on wind speeds and on adjusted 

hourly emissions rates for each parcel and summed over the entire year.

a. Assigning Each Parcel to a Land Use Category 

To account for land use differences and corresponding variances in the ratio of disturbed versus 

stable land, each parcel was allocated to a particular land use category. See Table 5-1 for a list 

of the land use categories for windblown emissions.

Table 5-1 Land Use Categories for Windblown Emissions

Developed Urban Lands55

Developed Rural Lands (low density residential)

Paved Roads56

Unpaved Roads

Cleared Areas

Residential Construction

Dairies

CAFOs

Desert Shrubland

Agriculture

Commercial Construction

Other

Site Development

Pinal County Air Quality Control District (PCAQCD) generally assigned a ratio of disturbed versus 

stable for each land use type according to predicted or regulated use of land and local 

expertise. However, for some land use categories such as agricultural crops, construction land 

use, and unpaved road, disturbed versus stable ratios had to be deduced more complexly 

because of ratio variability within the land use. 

5.2.1.1.1 Agricultural crop land use category ratio 57

The agriculture crop land use category’s disturbed versus stable ratio depends on the crop 

distribution (barley, corn, cotton, etc.) and corresponding crop stage (i.e. planting, harvesting, 

growing season, and between harvest and planting) ADEQ used GIS shapefiles, the 2007 USDA 

Agricultural Census, and a PCAQCD supplied crop calendar to determine the distribution of 

disturbance levels by crop type across the year. Once the crop distribution and associated crop 

specific stability ratio within the nonattainment area were determined, ADEQ calculated the 

55 Note that unpaved parking is not included in this land use category list, although it is listed as an activity for 

activity-based emissions. For windblown emissions, unpaved parking is enveloped within windblown dust subtotals 

from Developed Urban, Developed Rural, and Cleared Areas land use categories. 56 The disturbance (and therefore the emission rate) for paved roads was essentially zero because of paved road 

maintenance within Pinal County. See Appendix B (EI TSD) Section 3.1.2, Table 3-46, fn. 103. 57 See Appendix B (EI TSD) Section 5.2 - Agricultural. 

December 21, 2015 Final 50

 
annual weighted average of disturbed and stable land for all agricultural cropland in the 

nonattainment area. These two weighted averages were assigned to each parcel in the 

nonattainment area for the crop land category. 

5.2.1.1.2 Construction land use categories ratios58

Construction ratios varied depending the type of construction occurring on each parcel (i.e. 

residential, commercial, or site development). ADEQ utilized recommended assumptions from 

the WRAP Fugitive Dust Handbook to determine the percentage of land on an active site that is 

disturbed during construction. This percentage of land was adjusted to account for dust 

suppression controls on construction sites in 2008.

5.2.1.1.3 Unpaved roads land use ratio59

Road square footage within the nonattainment area was derived from a road network provided 

by Pinal County. Unpaved road disturbance level varies depending on whether the roads in 

question are private, public, agriculture roads, or trails. For all roads types except public, the 

roadway was considered fully disturbed. Due to regular maintenance on public roadways, these 

roadways were assumed to be 75% disturbed and 25% stable.

b. Grouping Parcels by Distance to Assign Meteorological Data60

Emission rates are wind speed dependent, therefore, assigning the most accurate 

meteorological data as possible to each parcel is crucial to determine an accurate emission rate.

In order to assign meteorological data, each land parcel in the nonattainment area was grouped 

to whichever of the six violating PM10 nonattainment area monitoring sites was closest as 

measured from the center point of the parcel to the monitor. 

c. Calculation of Friction Velocity for Wind Speed Bins

Friction velocity is the shear stress, or, the force of friction imposed by a fluid’s flow (in this case 

wind) passing over a parallel boundary surface (in this case the Earth’s rough planar surface),

re-phrased in units of velocity.61 It becomes relevant to determine speed dependent friction 

velocities for calculation of emission rates. Sierra Research determined threshold friction 

velocity utilizing previously reported methods and data. 

The threshold friction velocity is the minimum speed at which windblown dust emissions are 

initiated at ground level, and it will often depend on the impacted soil types.62 MAG’s previous 

58 See Appendix B (EI TSD) Section 5.2 - Construction. 59 See Appendix B (EI TSD) Section 3.1.2 for more information. 60 See Appendix B (EI TSD) Section 5.2 for more information. 61 See generally, CLAYTON T. CROWE, ET AL., ENGINEERING FLUID MECHANICS 281-301 (Jennifer Welter et al. eds., 9th ed. 

2009).

62 See Maricopa County, 2008 Maricopa PM10 Periodic Emission Inventory, Appendix 4, 4-4 available at 

http://www.maricopa.gov/aq/divisions/planning_analysis/docs/2008_PM10/App4_WindblownDust.pdf .

December 21, 2015 Final 51

 
analysis of non-agricultural land use soils,

63 and Sierra Research’s subsequent analysis of 

agricultural land use soils,

64 show that all soils throughout the nonattainment area display 

similar relationships concerning wind speeds and corresponding PM10 concentrations. 

Examination of local PM10 concentration and meteorological monitoring show that when wind 

speeds are 12 mph or higher, average PM10 concentrations are consistently higher than 

concentrations at lower speeds.65 Therefore, throughout the emission inventory analysis (and 

attainment analysis), ADEQ follows MAG’s conclusion that 12 mph is a valid approximation of 

the threshold 10 meter wind speed required for the initiation of windblown dust in the 

nonattainment area. Therefore, ADEQ concludes that 12 mph or more is a high wind speed. 

Recorded wind speeds were first normalized to speeds to a 10 meter measurement height 

because wind speeds change with the height from the earth’s surface due to a lessening of 

surface roughness friction drag with increased height from the surface.

66 To normalize the 

recorded wind speeds to the same height of 10 meters, ADEQ converted wind speeds at the 

height they were recorded to speeds at 10 meters by using the wind profile power law equation

so that the measured speed heights would be consistent with the applicable fluid dynamics 

equation to convert the wind speeds in the friction velocities. ADEQ then grouped these speeds 

into one mph wind speed bins (i.e. 12, 13, 14).67 The resulting whole number 10 meter speeds 

were used for all ensuing calculations throughout the nonattainment area. 

Each wind bin speed was subsequently converted to friction velocities for further calculations. 

To do this, ADEQ relied on previous wind tunnel studies conducted in Arizona. The studies 

resulted in a nonattainment-wide applicable coefficient to allow conversion of 10 meter wind 

speeds into friction velocities using a speed dependent equation.68 

d. Converting Friction Velocities to Emission Rates (Vertical Flux Rate)

Emission factors calculated previous to the initiation of this plan were applied to all disturbed 

soils throughout the nonattainment area. These emission factors were based on wind tunnel 

studies of disturbed exposed soils in Maricopa and Pinal Counties. These factors were 

proportionally modified to account for stable soils, based on another study conducted in 

Barstow, California.69

63Id. at 4-5. 64 See Appendix B, Exhibit BVI for more information. 65 See generally “Evaluation of Aerosol Production Potential of Type Surfacesin Arizona,” prepared for EngineeringScience by W.G. Nickling and J.A. Gillies, for EPA Contract No. 68-02-380, September 1986. See Appendix B, Exhibits 

BV and BVI.

66 See generally ENGINEERING FLUID MECHANICS,supra note 61. 67 This approach is unlike in the mag plan where they grouped wind speeds in 5 mph bins because no speeds above 

25 mph were recorded at Pinal County Housing over the 2008 year, hence all the high wind speeds were grouped 

within just two 5 mph bins, allowing for only limited emission rate accuracy. See Appendix B, Exhibit BV for more 

information.

68 See Appendix B (EI TSD), Exhibit BVI for more information regarding the Prandtl equation. 69 2008 Maricopa PM10 Periodic Emission Inventory, supra note 62 at 4-8.

December 21, 2015 Final 52

 
The Arizona wind tunnel studies provided limited information on emission rates from stable 

soils.70 However, the results of similar studies conducted in Barstow, California indicated that 

the stable soil produced emissions at a rate of about 12 to 20% of the disturbed soil.71 

Therefore, after the disturbed soil emission factors were computed, the Barstow emission 

factor ratio (varying between the aforementioned percentages) was applied to the disturbed 

soil emission factors, in order to compute the emission factors for each wind bin speed.72 

For various data availability reasons, emission factors for disturbed and stable soils were 

computed for both (and only) the Pinal County Housing and the Stanfield monitors. The other 

four monitors were grouped to either the emission factors computed for PCH or to those for 

Stanfield, depending on which of the two monitors was closest. These emission factors were 

then applied to the wind speed bins (velocities) and ensuing parcels for each of the monitors. 

e. Emission Adjustment Factor Application73

Additionally, in the high wind annual calculation process ADEQ applied an adjustment factor to 

account for temporal variation of emission rates during a wind event. Windblown emission 

factors are generally an estimation of maximum emission potential and, thus, are not always 

representative of the actual environment. Specifically, land use dependent emission factors 

assume static emission rates for a given wind speed throughout the progression of a wind 

event. In reality, emission rates vary with time as well as wind speed for reasons such as lack of

airborne particles available for re-entrainment (beginning of wind event) or reservoir depletion 

of ground particles (end of wind event). Therefore, ADEQ applied distribution curves to the 

estimated emissions during criterial high wind events throughout 2008 to more accurately 

represent 2008 annual emissions.

f. Sum of High Wind Emissions74

As a last step, for each parcel, individual wind event emissions were calculated based on wind 

speeds and adjusted hourly emissions rates. These parcel specific emissions were then 

summed over the entire year of 2008.

5.2.2 Adjusting and Projecting the 2008 Base Year Emissions to 2018

The disturbed versus stable ratios for the above described land use categories were adjusted to 

project emissions from 2008 to 2018. Adjusting these ratios varied depending on land use. For 

example, some concentrated animal feeding operations (CAFOs) have closed since 2008 and are 

projected to be cleared areas in 2018. Unpaved roads that have either undergone or are 

scheduled in Transportation Infrastructure Plans (TIPs) to undergo improvements such as 

70 Id. 71 Id. 72 Appendix B (EI TSD), Exhibit BV-3. 73 For more information, see Appendix B (EI TSD), Exhibit BVII. 74 Note that high wind events with .01 inches or more of recorded precipitation at a monitor were not included. 

December 21, 2015 Final 53

 
paving were assigned controlled emissions rates dependent on the control applied. For 

construction, analysis of permit issuance and projected population growth was used to adjust 

emissions to 2018.75 

5.3 Activity-Based Emissions for the Base Years 2008 and 

2018

Below are short summary glimpses as to how activity emissions were calculated for the 

nonattainment area annual inventories. These emissions calculations do not take wind into 

account. Emissions for each category presented in Table 5-2 were calculated for one year and 

results from each category were summed to represent all activity emissions within the 

nonattainment area over an entire year. More information is in the Emission Inventory TSD in 

the sections cited for each category below.

Table 5-2 Activity-Based Emission Source Categories

Ag Fields (Harvesting & Tilling)

CAFOs

Dairies

Paved Road

Unpaved Road (Public, Private, Agricultural, and Trails)

Nonroad 

Railroad

Construction (Residential, Commercial, Road, and Site 

Development)

Permitted Sources

Fuel Combustion (Residential)

Fires (Agricultural, Wildfires, and Prescribed Fires)

Open Burning (Residential, Commercial, and Land Clearing)

Unpaved Parking

5.3.1 Agriculture Crop Emissions

a. Generally

To compute annual emissions within the entire nonattainment area, ADEQ relied on estimates 

of the annually harvested crop distribution from the 2007 USDA Agricultural Census for major 

crops within Pinal County. This crop distribution was then scaled to the nonattainment area 

based on the ratio of crop agricultural lands identified in the PCAQCD/ADEQ land use map for 

75 For more information, see Appendix B (EI TSD) Sections 5.1.7 and 5.2.

December 21, 2015 Final 54

 
the nonattainment area and the total acreage reported harvested in the 2007 USDA 

Agricultural Census for the County.

Tillage activity emissions were calculated using an AP-42 tillage emission factor equation as 

used in ADEQ’s 2001Agricultural BMP TSD,76 taking into account local Pinal county silt content 

and the closest estimate particle size. The emission factor results were then multiplied by the 

total estimated number of crop-specific acre-passes related to local West Pinal tilling 

activities.77

Harvesting emissions were estimated using crop-specific emission factor equations 

promulgated by California Air Resources Board, factoring local harvesting activity on each crop 

specific parcel and respective acreage, per year.78

b. Projecting Emissions to 2018

For the 2018 annual inventory, no change was made to the amount of land under cultivation or 

the methods employed in the 2008 calculations. Agricultural emissions were held constant 

from 2008 to 2018.79

5.3.2 Concentrated Animal Feeding Operations (CAFO) Emissions

a. Generally

Annual PM10 emissions generated by CAFOs within the nonattainment area in 2008 were 

computed using an average daily PM10 emission factor;

80 and 2008 animal population averages 

for affected facilities were provided by representatives of the Arizona Cattle Feeders 

Association.81 

b. Factoring growth between 2008 and 2018

While the same method was used as for 2008, the estimates of the cattle population were 

revised to address the closure of feedlots that have occurred to date. For windblown PM10 

emissions estimations, these locations were assumed to transition from the CAFO land use to 

Cleared Areas. Projected animal populations were supplied by industry contact.82 ADEQ has 

confirmed through aerial photography and site visits that these facilities no longer exist.

76 Section 9.1 of AP-42 (U.S. EPA, 1995) 77 See Appendix B (EI TSD) Section 3.1.1.1 for more information. 78 Id. 79 See Appendix B (EI TSD) Section 5.1.1 for more information. 80 This emission factor is further described in Section 3.1.1.2 of Appendix B (EI TSD). 81 See Appendix B (EI TSD) Sections 3.1.1.2 and 5.1.2. 82 Id.

December 21, 2015 Final 55

 
5.3.3 Dairy Emissions

a. Generally

Annual PM10 emissions for dairy operations in the nonattainment area in 2008 were derived 

from an emission factor published by the Arizona Governor’s Agricultural BMP Committee, and 

estimates of average annual animal populations at affected dairies provided by United

Dairymen of Arizona.

83

b. Factoring growth between 2008 and 2018

The emission estimates employed in the 2008 inventory were held constant for 2018; however, 

the estimated number of head decreased from 71,624 in 2008 to 70,644 in 2018 due to facility

closure.

5.3.4 Fugitive Dust and Exhaust Emissions from Paved Roads

a. Generally

The new AP-42 equation published by EPA in January 2011,84 a function of silt loading values 

and the average weight of vehicles traveling on paved roads, was applied to estimate 

reentrained PM10 emissions from paved roads in the nonattainment area. The silt loadings and 

average vehicle weights were derived from the MAG 2012 Five Percent Plan for PM-10. Paved 

roads were split into four different silt loading categories, producing four different PM10

emission factors from the AP-42 equation. These emission factors were applied to estimated

road segment specific vehicle miles traveled (VMT) values to produce 2008 fugitive dust 

particulate emissions from paved roads for the West Pinal PM10 nonattainment area. The 

estimated 2008 VMT values for the West Pinal PM10 nonattainment were obtained from MAG’s 

TransCAD model outputs for the year 2008 in the nonattainment area.

85 For those road 

segments identified by PCAQCD as containing trackout, the emission factor was increased 381% 

as described in section 3.1.1.6 of Appendix B. Paved road reentrained fugitive dust was then 

summed for all road segments in the nonattainment area.

Vehicle exhaust, tire, brake, and starting emissions were calculated using MOVES inventory 

simulations.86 Bow wake emissions from large trucks was estimated by applying a Sierra 

Research developed emission rate formula87 to roadways identified by the Arizona Department 

of Transportation (ADOT) as having significant heavy duty vehicle traffic and unpaved road 

shoulders.

83 See Appendix B (EI TSD) Section 5.1.9 for more information. 84 Section 13.2.1 of AP-42. 85 See Appendix B (EI TSD) Section 5.1.3 for more information. 86 Id. 87“Cost-Effectiveness of Selected PM10 Control Measures,” prepared for Maricopa Association of Governments by 

Sierra Research, June 2006, p. 26.

December 21, 2015 Final 56

 
b. Factoring growth between 2008 and 2018

2018 paved road segment VMT values were interpolated from MAG’s TransCAD model results 

for 2015 and 2025.

88 The travel network links and road categories were defined from MAG’s 

2015 model results.

Road segments identified to contain trackout or produce bow wake emissions in 2008 were also 

assumed to do so in 2018.

5.3.5 Fugitive Dust and Exhaust Emissions from Unpaved Roads

a. Generally

AP-42 emission factors and guidance were applied to unpaved road VMT values to estimate 

fugitive PM10 emissions.89 The AP-42 equation takes into account several factors including 

particle size, surface silt content, mean vehicle speed, surface moisture content, mean vehicle 

weight, the annual number of wet days, and the annual number of days. 

Four categories of unpaved roads have been identified in Pinal County: agricultural, public, 

private, and trails. Each was determined to have different surface silt and moisture contents, 

estimated from a Pinal County field study conducted in June 2013. The four categories were 

additionally split into different classes of roads to account for varying annual average daily 

traffic (ADT) counts and estimated mean speeds ranging between 15 mph and 47 mph.

ADT is multiplied by total mileage of each respective road to calculate daily VMT. The PM10

emission factors were multiplied by the VMT to produce unpaved road emissions for the PM10

nonattainment area in 2008.

Unpaved exhaust emission rates were estimated as vehicle-population-weighted average 

exhaust emission rates for a given unpaved road’s estimated average speed bin. Rates were 

extracted for 2008 using results from the existing Pinal County configured MOVES results.90

b. Factoring growth between 2008 and 2018

Except for the unpaved public and private roads, the methods and travel activity employed in 

the 2008 calculation for the unpaved road emissions (unpaved Ag road, unpaved trails, and test 

tracks) were held constant for 2018. For unpaved public and private roads, ADTs were assumed 

to experience growth equivalent to those reported for HPMS data from 2008 to 2013 and 

equivalent to population projected growth between 2013 and 2018.91 Additionally, numerous 

unpaved public road projects were completed or planned between 2008 and the end of 2018. 

88 Id. 89 AP-42 Section 13.2.2 90 See Appendix B (EI TSD) Section 5.1.4 for more information. 91 See Appendix B (EI TSD) Section 3.1.1.4 for more information.

December 21, 2015 Final 57

 
For exhaust emissions, emission rates were extracted for 2018 using results from the existing 

Pinal County configured MOVES results.92

5.3.6 Nonroad Emissions

a. Generally

With the exception of the locomotive and aircraft categories, all nonroad combustion emissions 

were calculated using Pinal County specific emissions from EPA’s NONROAD model. NONROAD 

calculates emissions as a function of deterioration factors, horsepower, load factor, annual 

operating hours, and engine unit populations.93

The NONROAD model calculates emissions from a varied assortment of equipment sources that 

are generally categorized. The model calculates emissions utilizing a “top down” approach. Its

default equipment populations are based on national averages, which are then scaled down to 

represent smaller geographic areas (i.e., statewide and countywide) on the basis of human 

population and other statistics.94 

b. Factoring growth between 2008 and 2018

Nonroad emissions were calculated for the 2018 calendar year scaling the 2018 equipment 

population by County population increases over the same period and assuming the emission 

rate per vehicle will stay constant over this period.95 

5.3.7 Railroad Emissions

a. Generally

EPA summarized emissions factors for locomotives in a 2009 study.96 The emission factors are 

used in calculating the annual railroad emissions by assuming two trains travel through the 

nonattainment area each hour, 366 days per year.97 

b. Factoring growth between 2008 and 2018

ADEQ used a forecasted emission factor for locomotives from EPA’s 2009 study.98 All other 

assumptions for calculating 2018 railroad emission, such as the railroad length and the number 

of trains per hour, are held the same as 2008.

92 Id. 93 See Appendix B (EI TSD) Section 5.1.5 for more information. 94 See Appendix B (EI TSD) Section 3.1.1.5 for more information. 95 See Appendix B (EI TSD) Section 5.1.5 for more information 96 Emission Factors for Locomotives, EPA-420-F-09-025, U.S. Environmental Protection, April 2009. 97 See Appendix B (EI TSD) Sections 3.1.1.7 and 5.1.6 for more information. 98 Emission Factors for Locomotives, supra note 96 at 8 (Table 6).

December 21, 2015 Final 58

 
5.3.8 Construction Emissions

a. Generally

The location of construction activity and related fugitive dust emissions shifts from year to year. 

The best source of information for tracking activity within a specific domain and time period is 

dust control permits and respective types, acreage, and site location. PCAQCD staff99 reviewed 

permits issued in late 2007 (4th quarter) and selected those that were most likely to continue

into 2008; these were then combined with permits issued in 2008 to create a shape file of 

polygons identifying the location and acreage of each of the issued permits. ADEQ calculated 

emission for each construction project by multiplying the number of acres by an annual 

emission factor that varies by project type and by the average duration for a project type. 

b. Factoring growth between 2008 and 2018

The county recorded the number of permits issued in the Pinal County nonattainment area 

through 2013. The ratio of the number of dust permits issued in 2008 and 2013 was used to 

project construction emissions from 2008 to 2013. The ratio of projected county population 

growth between 2013 and 2018 was used to project future construction permitting and ensuing

emissions from 2013 to 2018.100 From 2013-2018, an economic improvement is accounted for 

by using the projected population growth factor.

5.3.9 Emissions from Permitted Stationary Sources

a. Generally

PM10 annual emissions (tons/yr) for each permitted stationary industrial/commercial facility in 

the nonattainment area were provided by the PCAQCD from permit files. PCAQCD permits 

include estimates of PM10 emissions for stationary sources only. PM10 emissions from area 

sources such as unpaved road travel, livestock movement, and windblown dust were estimated 

separately and these separate methodologies are discussed in other sections.

b. Factoring growth between 2008 and 2018

The emission estimates calculated for the 2008 inventory were held constant for 2018. 

5.3.10 Fuel Combustion Sources

Fuel combustion emissions were estimated for: (1) Fires – including prescribed, wildfires, and 

agricultural field burning; (2) Residential Fuel Combustion – from fuels including natural gas, oil, 

wood, and other; and (3) and Open Burning – including residential, commercial and land 

clearing of debris. In the case where local permit data was available, this information was used

99 Email from Kate Edwards, Pinal County to Bob Dulla, Sierra Research, 2008 Construction Dust Permits, November 

28, 2012.

100 See Appendix B (EI TSD) Sections 5.1.7 for more information.

December 21, 2015 Final 59

 
for the estimation of combustion emissions in conjunction with EPA approved emission factors. 

In those instances where local permit data was not available ADEQ and PCAQCD allocated EPA 

NEI estimates of combustion emissions. Emissions were held constant between 2008 and 

2018.101

5.3.11 Unpaved Parking

Unpaved parking emission estimates utilized a modified version of the methodologies 

presented in the 2008 Maricopa County PM10 Emission Inventory for reentrainment. Emissions 

were held constant from 2008 to 2018.102

5.4 Comparison of Base Year Inventories to Control 

Inventories

Table 5-3 Comparing Base Year 2008 to Base Year 2018 to Post Control 2018 Inventories

ADEQ estimated the following 

emissions reductions based on 

2018 assumptions (e.g., that 30 

miles of unpaved road controls 

are in place, implemented in 

2016 and 2017). All reductions 

are presented in tons per year 

(TPY).

Base 2008 

Emissions 

Inventory 

(TPY)

Base 2018 

Emissions 

Inventory 

(TPY)

Attainment 

2018 

Emissions 

Inventory 

(TPY)

Postcontingency 

2018 

Emissions 

Inventory 

(TPY)

Windblown dust

Developed Urban Lands 200.7 248.1 248.1 199.8

Developed Rural Lands (low 

density residential) 1959.7 1959.7 1959.7 1899.3

Unpaved Roads 4688.6 4653.0 3803.1 3793.8

Cleared Areas 398.1 457.0 457.0 325.8

Residential Construction 1302.4 837.5 837.5 430.5

Dairies 449.6 449.6 449.6 384.2

CAFOs 273.7 155.2 125.3 125.3

Desert Shrubland 38276.7 38276.7 38276.7 36719.3

Agriculture 19510.1 19510.1 7122.0 7122.0

Commercial Construction 686.4 441.4 441.4 216.3

Other 4243.9 4243.9 4243.9 4242.1

Site Development 858.7 552.2 552.2 278.9

Subtotal 72848.6 71784.4 58516.5 55737.3

101 See Appendix B (EI TSD) Sections 3.1.1.11 and 5.1.10 for more information. 102 See Appendix B (EI TSD) Sections 3.1.1.9 and 5.1.8 for more information.

December 21, 2015 Final 60

 
Activity-based emissions

Ag Fields - Harvesting 312.9 312.9 207.1 207.1

Ag Fields - Tilling 2540.3 2540.3 1658.0 1658.0

CAFOs 2614.3 1620.6 1369.2 1369.2

Paved Road 1180.7 1408.0 1408.0 1402.3

Unpaved Road 45127.8 45105.3 37186.4 36053.0

Fuel Combustion 28.3 34.9 34.9 34.9

Fires 19.9 22.2 22.2 22.2

Open Burning 13.6 16.8 16.8 16.8

Nonroad 121.3 144.4 144.4 144.4

Railroad 85.9 45.4 45.4 45.4

Construction 12955.3 8499.8 8499.8 4718.5

Dairy 186.6 184.0 184.0 148.2

Permitted Sources 781.3 781.3 781.3 781.3

Unpaved Parking 251.5 251.5 251.5 172.5

Subtotal 66219.7 60967.4 51809.0 46773.8

Total 139068.3 132751.8 110325.5 102511.1

Required contingency measures (equal to 1 year of RFP out of 3 total RFP years) =22426.3 ∙ 1⁄3 

=7475.4 TPY

5.5 Motor Vehicle Emissions Budget (MVEB) Summary

Transportation conformity is required by Section 176(c) of the CAA. Under EPA’s transportation 

conformity regulations, transportation plans and improvement programs must be consistent 

with, or conform to, the motor vehicle emissions budget (MVEB) defined in the applicable 

SIP.103 These budgets specify the level of on-road motor vehicle emissions that are consistent 

with attainment and maintenance of air quality standards and should include an adequate 

safety margin.104

The budget considers the combined contributions of motor vehicles traveling roads within the 

nonattainment area, as well as the emissions from construction projects on those roads. 

Emissions from non-road vehicles are not included in the budget, nor are emissions produced 

by wind traveling over the roads and construction sites. Emissions from certain commercial 

roads, which are expected to remain fairly constant from one year to the next, are also omitted. 

The budget is established for annual emissions totals, and anticipates various changes in traffic, 

fleet characteristics, road work, and new rules and regulations up through calendar year 2018.

103 Conformity Criteria and Procedures: Motor vehicle Emissions Budget, 40 C.F.R. § 93.118 (2015). 104 Safety margin means the amount by which the total projected emissions from all sources of a given pollutant 

are less than the total emissions that would satisfy the applicable requirement for reasonable further progress, 

attainment, or maintenance. Conformity Definitions, 40 C.F.R. § 93.101 (2015).

December 21, 2015 Final 61

 
From the 2018 attainment inventory, ADEQ developed a comprehensive MVEB for the 

nonattainment area. See the summary MVEB totals in Table 5-4 below. 

Table 5-4 Annual MVEB by Source Sector

Source Tons of PM10

Exhaust, tire-, & brake-wear 173.7

Unpaved road dust105 26,433.5

Reentrained paved road dust 1,211.1

Road 

construction/maintenance106 168.8

Total 27,987.1

The emissions total of 27,987.1 tons accounts for more than a quarter of the total attainment 

inventory; therefore, keeping motor vehicle emissions within this budget is critical to reaching 

attainment. The budget allows for a small safety margin of 81 tons.

Modeling indicates that the nonattainment area will not violate the 24-hour PM10 national 

ambient air quality standard (NAAQS) as long as this budget is not exceeded, and as long as the 

emissions are distributed appropriately, using planning tools such as hotspot analyses to 

prevent high concentrations of PM10 building up in a given place and time. 

ADEQ has consulted Pinal County, Arizona Department of Transportation (ADOT), and Maricopa 

Association of Governments (MAG) regarding the development of the MVEB for this West Pinal 

PM10 SIP. MAG is the designated metropolitan planning organization (MPO) for Maricopa 

County and portions of Pinal County, including the City of Apache Junction, the Town of 

Florence, the City of Maricopa, and some rural portions of Pinal County.

107 MAG is responsible 

for preparing the Transportation Improvement Program (TIP), Regional Transportation Plan

(RTP), and the associated transportation conformity analyses for the above mentioned member 

agencies. Since 2013, MAG has been conducting the interim emissions test conformity analyses 

for both the West Pinal PM10 and the West Central Pinal PM2.5 nonattainment areas as portions 

of MAG member agencies are located within these areas. 

The Sun Corridor MPO, established in 2013, provides transportation planning services to the 

communities of Casa Grande, Coolidge, Eloy and some rural portions of Pinal County.

108 ADEQ 

also consulted with the Sun Corridor MPO regarding the MVEB in this West Pinal PM10 SIP. 

Some portions of the West Pinal PM10 nonattainment area are located within MAG’s 

105 The projected emissions totals for unpaved road dust and construction may be overestimates, since they do not 

consider the reductions that would be provided by control measures in upcoming Pinal County rules. This omission 

is intentional; the reductions from the upcoming rules are set aside as contingency measures to counterbalance 

unforeseen PM10 emissions growth. The additional controls from these rules are expected to increase the 

budget’s safety margin by over 1,000 tons in 2018. 106 See note 105 above. 107 Designation of Areas of Air Quality Planning Purposes; State of Arizona, Pinal County PM10, 77 FR 32024, 32030 

(May 5, 2012) available at http://www.regulations.gov/#!documentDetail;D=EPA-R09-OAR-2010-0491-0063. 108 SunCorridor Metropolitan Planning Organization, Home, http://scmpo.org/ (last visited Sept. 2, 2015).

December 21, 2015 Final 62

 
jurisdictional boundary, and because Sun Corridor is a new MPO, MAG has agreed to continue 

preparing the conformity analyses for the entire West Pinal PM10 nonattainment area. It is for 

this reason that ADEQ primarily consulted with MAG and ADOT to review this MVEB. Subject to 

EPA’s approval and finding of adequacy, the MVEB in this West Pinal PM10 SIP will be used in 

future conformity analyses. 

For more details regarding MVEB calculations and the relationship between the annual 

emissions inventory, modeling, and the conformity budget, see Appendix D (Attainment TSD),

Section D4.

December 21, 2015 Final 63
6 CONTROL MEASURES

The Clean Air Act section 172(c)(1) requires that “[nonattainment plan] provisions shall provide 

for the implementation of all reasonably available control measures as expeditiously as 

practicable...and shall provide for attainment of the national primary ambient air quality 

standards.” In reviewing a statute, regulation or rule for SIP approval, EPA looks to ensure that 

the provision is enforceable as required by CAA section 110(a) and is consistent with all 

applicable EPA guidance.

CAA section 172(c)(9) requires that the 189(a) plan provide for the implementation of 

contingency measures, which are to be undertaken if the area fails to make RFP or to attain the 

PM-10 standard as projected in the plan. Such measures shall take effect without further 

action, such as public hearings or legislative review, by the state or EPA. EPA has interpreted 

section 172(c)(9) to allow states to implement contingency measures before they are triggered 

by a failure of RFP or attainment as long as those measures are intended to achieve reductions 

over and beyond those relied on in the attainment and RFP demonstrations.109 The CAA does 

not specify how many contingency measures are necessary nor does it specify the level of 

emission reductions they must produce. 

ADEQ believes that the submitted (or soon to be submitted) control measures qualify as 

reasonably available control measures (RACM). For a full RACM discussion, see Appendix F. 

ADEQ has also projected attainment by the required date, which is the end of December 2018, 

and the efficacy of chosen contingency measures to ensure RFP past the attainment date. The 

contingency measures will take effect presently to avoid any necessary future further action by 

the state or the EPA. Pinal County’s general fugitive and construction rules are now final rules, 

effective in January 2016. ADEQ’s and Pinal County’s chosen control measures to meet 

attainment and contingency measure requirements are described below. 

6.1 Agricultural Rule – Attainment and Contingency in Part

6.1.1 Commercial Farms Summary (R18-2-610 and -610.03)

The commercial farms rule was credited towards attainment. The rule requires new controls

for commercial farmers in the Pinal County PM Nonattainment Area, as defined in R18-2-610 

(37). Commercial farmers in that area are required to implement one Best Management 

Practice (BMP) every day of the year from the tillage, ground operations and harvest, 

commercial farm roads, noncropland, and significant earth moving categories, and two BMPs 

109 See Proposed Approval of Maricopa County Serious Nonattainment Area Plan, 75 FR 54806, 54815 (Sept. 9, 

2010). See generally, LEAN v. EPA, 382 F.3d 575 (5th Cir. 2004). See also General Preamble for the Implementation 

of Title I of the Clean Air Act Amendments of 1990, 57 Fed. Reg. 13,498, at 13512.

December 21, 2015 Final 64

 
from the cropland category. On the day before and during a day (or, depending on the BMP, 

just the day) forecast to be high risk for dust generation, as determined by the dust control 

forecast (R18-2-610 (18)), a commercial farmer is required to ensure implementation of one 

BMP that is in the high risk category for tillage, ground operations and harvest, cropland, 

commercial farm roads, and noncropland. If a commercial farmer implements conservation 

tillage or a reduced tillage system for the tillage category on a crop, he/she does not have to 

implement a BMP for ground operations, harvest, or cropland for that crop acreage, whether or 

not a day is forecasted to be high risk.

6.1.2 Appendix 2 – Test Method for Silt Loading

Appendix 2 is also submitted into the Arizona SIP. It will be used to determine compliance with 

sections requiring the use of a silt test method in the commercial farms rule.

6.1.3 Commercial Animal Operations Summary (R18-2-611 and -

611.03)

Generally, the animal operations rules are credited towards attainment, except for those

animal operations not yet existing in the nonattainment area (e.g. poultry and swine 

operations). However, the section applicable to commercial dairy operations was credited 

toward contingency measures,

The rule requires new controls for commercial animal operators in the Pinal County PM 

Nonattainment Area defined in R18-2-611(1)(i). Commercial animal operators are required to 

implement one BMP every day of the year from the arenas, corrals and pens, animal waste (and 

feed) handling and transporting, unpaved access connections and unpaved roads or feed lanes 

categories. For beef cattle feedlots, in addition to selecting one BMP from each category, on 

the day that is forecast to be high risk for dust generation, as determined by the dust control 

forecast, must add water to pen surface, as defined in R18-2-611(3)(a). 

For commercial dairy operation, in addition to selecting one BMP from each category, on the 

day that is forecast to be high risk for dust generation, as determined by the dust control 

forecast, must apply and maintain one of the four following BMPs on unpaved roads that 

experience more than 20 VDT from 2 or more axle vehicles:

1. Apply and maintain pavement in high traffic areas,

2. Apply and maintain aggregate cover,

3. Apply and maintain synthetic particulate suppressant, or

4. Apply and maintain water as a dust suppressant.

December 21, 2015 Final 65
6.1.4 Irrigation Districts in the Pinal County PM Nonattainment Area 

(R18-2-612 and -612.01)

Rule R18-2-612 was renumbered and rule R18-2-612.01 was added in order to provide 

definitions and BMPs for irrigation districts only within the Pinal County PM Nonattainment 

area. Senate Bill 1408 (Forty-ninth Legislature, Second Regular Session, 2010, Chapter 82, § 1) 

adds the activities of irrigation districts in regulated areas established after June 1, 2009. This 

rule adds requirements for irrigation districts to implement one BMP from the unpaved 

operation and maintenance roads, canals, and unpaved utility access roads categories. No 

credit was taken for access road provisions, but attainment credit was taken for operation and 

maintenance irrigation roads.

6.1.5 Implementation Schedule – Agricultural Rules

The Arizona Administrative Code Agricultural Rules were effective upon filing with the Arizona 

Secretary of State, as of July 2, 2015. 

The rules must be complied with beginning January 1, 2016. The rules mandate that by 

December 31, 2015, agricultural sources engaged in regulated agricultural activity must 

complete a BMP Program General Permit Record Form, and must complete such form every 

year thereafter by March 31. 

6.1.6 Enforceability

6.1.6.1 Commercial Farms

6.1.6.1.1 Authority

The Agricultural BMP Committee has the statutory authority to adopt the Agricultural BMP 

commercial farm rules under A.R.S. § 49-457(H). Under A.R.S. §§ 49-457(I), (J), and (K), ADEQ 

has the statutory authority to enforce a regulated person’s compliance with the rules and 

general permit program. ADEQ has additional enforcement authority under A.R.S. §§ 49-460, -

461, -462, -463, and -464, which ADEQ will resort to if measures taken under A.R.S. §§ 49-

457(I), (J), and (K) are unsuccessful to return a facility to compliance. 

6.1.6.1.2 Applicability

The crop operations rules apply to commercial farmers who engage in regulated agricultural 

activity in the Pinal County PM Nonattainment Area. A commercial farmer is an individual, 

entity, or joint operation in general control of more than 10 or more contiguous acres of land 

used for agricultural purposes. “Regulated activity” upon such farms would be those activities 

or sources statutorily defined in A.R.S. § 49-457(P), consisting of tilling, harvesting (including 

ground operations), and those areas of a commercial farm that are not normally in crop 

production (such as commercial farm roads and noncropland as defined in the submitted rule), 

those areas that are normally in crop production including prior to plan emergence and when 

December 21, 2015 Final 66
the land is not in crop production (covering cropland as defined in the submitted rule), and 

earthmoving activities.

6.1.6.1.3 Exemptions

Exemptions from the rule’s requirements only apply to farmers who choose to implement 

conservation tillage or reduced tillage system BMPs for the tillage category. If farmers choose 

either of these BMPs for the tillage category, they do not have to implement BMPs for ground 

operations and harvest on either a regular or high risk day, nor would they have to implement 

BMPs on cropland on either a regular or a high risk day. These exemptions exist because both 

BMPs, conservation tillage and reduced tillage systems, have control efficiencies which 

temporally affect other regulated activities or sources during multiple planting phases. Both 

BMPs can provide adequate control against tillage emissions and either leave plant stubble 

protruding from the ground or leave plant material laying on the field's surface, providing 

control of windblown dust year-round.

6.1.6.1.4 Alternative Practices

A farmer may develop different practices to choose as BMPs to control PM emissions, but such 

practices will not be effective until they are submitted as a SIP revision to the EPA per A.R.S. § 

49-457(L). Additionally, as provided by A.A.C. R18-2-610.03(E), any alternative practices must 

be “proven effective through on-operation demonstration trials to the Committee.” The already 

statutorily stated purpose of BMPs is to reduce PM10 emissions.110 Therefore, before submittal, 

these alternative practices would be thoroughly evaluated on a case-by-case basis by the 

Agricultural BMP Committee, and ADEQ would provide technical input as needed, and any 

other advice, as needed, to ensure the newly developed practice is sufficiently effective to 

control PM10. 

6.1.6.1.5 Notice

The definitions and rule requirements are sufficiently clear so as to put the regulated public on 

notice. Where needed, many definitions rely on specific test methods and are extremely

detailed. ADEQ and the Agricultural BMP have worked together to ensure that the rule is clear 

and understandable. The West Pinal County applicable commercial farms rule is more 

comprehensive and specific than the previous Maricopa rule, which has been in place for 

several years, in its current and modified forms.

111 

As far as outreach is concerned, the Agricultural BMP statute that establishes the Agricultural 

BMP Committee requires the Committee to develop and commence an education program. 112

The Agricultural BMP Committee has been working fervently to develop a program for the Pinal 

nonattainment area community. The outreach developed thus far is very thorough and 

110 A.R.S. § 49-457(H) (2015). 111 See generally, Approval and Promulgation of Maricopa PM-10 Arizona Implementation Plan, 66 FR 51869 (Oct. 

11, 2001).

112 A.R.S. § 49-457(M) (2015).

December 21, 2015 Final 67

 
informative. The Committee has created a guidebook, specific to this rule, to help the regulated 

public understand the new standards. There will be information disseminated, also, explaining 

how to sign up for the high risk forecast, which is critical to the rule’s effectiveness and 

penetration. The Committee intends to supply these extensive informational guidebooks at 

several outreach meetings over the course of the months between October 2015 and January 

2016, to ensure compliance with the rule by the compliance date. The meetings will be held 

within the nonattainment area where the Committee will explain the importance of complying 

with the rule. Additionally, the Committee, ADEQ, and the Department of Agriculture are

working diligently to develop a comprehensive 3-year survey as required by the rule. 

6.1.6.1.6 Compliance Schedule

As previously stated, per the Agricultural BMP statute as revised, A.R.S. § 49-457, “[a] person 

who commences a regulated agricultural activity shall immediately comply with the agricultural 

general permit [prescribed by the statute].” Immediate compliance, in this case, would be after 

December 31, 2015, beginning January 1, 2016, as required by the commercial farm rule. 

6.1.6.1.7 Records

A General Permit Record Form must be filled out and kept as a record onsite and made 

available for review within two business days of notice. The requirements for the record form 

are listed in A.A.C. R18-2-610.03(C), and shall include notation, of the categorical best 

management practices a farmer has chosen to apply a regulation basis and on high risk days, as 

applicable. Such form shall also include a notation of any changes. The purpose of the record 

form is to assist inspectors with enforcement and to hold facilities accountable for their BMPs 

chosen. 

Beginning January 1, 2016, a commercial farmer must maintain records demonstrating 

compliance with the rules for three years, including a copy of the BMP Program General Permit 

Record Form. Additionally, by January 31, 2018, farmers must submit their first BMP 3-Year 

Survey which reflects the BMPs chosen in the previous calendar year. The next due date after 

January 31, 2018, will be January 31, 2021 (reporting on 2020), and every three years 

thereafter. The required information is listed in A.A.C. R18-2-610.03(D), and will ensure that 

facilities are held accountable for the required BMPs and will also provide ADEQ with the 

necessary information for future emissions calculations.

6.1.6.1.8 Test Methods and Compliance

Compliance is determined by inspection and records review. ADEQ will enforce the rule as 

necessary and as authorized, but its primary goal will be to ensure ADEQ takes advantage of 

every opportunity to provide compliance assistance to prevent any violations. Preventing 

violations is the most effective form of protection of human health and the environment. The 

agricultural community is very close-knit in Arizona and has complex needs. Inspectors are 

linked by cell phone to instant monitor alerts, even in the middle of the night. ADEQ’s 

compliance section is extremely responsive to such alerts and any complaints. ADEQ responds 

to such alerts and complaints with contact and/or an inspection of the problem area, in 

December 21, 2015 Final 68
addition to regular monthly inspections of various agricultural facilities according to internal 

goals.

Test methods include those listed in Table 6-1 below.

Table 6-1 Commercial Farms Rule Test Methods

Test Method Location in the rule and purpose

NRCS Practice Code 609, Surface Roughening, 

amended through November 2008.

R18-2-610 (53), in the definition of “surface 

roughening,” to ensure the soil surface is 

manipulated to produce clods on the land surface, if 

implementing the BMP on cropland

NRCS National Agronomy Manual, Subpart 

503.51, Estimating Crop Residue Cover, 

amended through February 2011.

R18-2-610 (14), in the definition of “cover crop,” to 

ensure the vegetation meets the minimum ground 

cover requirement of 60%, if implementing the BMP 

on cropland

R18-2-610 (15), in the definition of “critical area 

planting,” to ensure 60% required ground cover if 

implementing the BMP on noncropland

R18-2-610 (36), in the definition of “permanent 

cover,” to ensure perennial species are used to meet 

minimum requirements of 60% ground cover if 

implementing the BMP on cropland 

R18-2-610 (47), in the definition for “residue 

management,” to ensure a minimum of 60% ground 

cover of crop or other plant residues between 

harvest and tillage, if choosing the BMP to control 

cropland

NRCS Estimating Soil Moisture by Feel and 

Appearance Method, amended through April 

1998.

R18-2-610 (39), in the definition of “planting based 

on soil moisture,” to ensure the appropriate amount 

of moisture to germinate seeds prior to planting, 

implementing the BMP for tillage

R18-2-610 (56), in the definition for “tillage based on 

soil moisture,” to ensure fields have the minimum 

required soil moisture content from irrigation or 

precipitation prior to soil disturbance, 

If implementing the BMP for tillage

R18-2-610.03 (B)(6), as the method for determining 

appropriate soil moisture for the applicable 

earthmoving activity BMPs

NRCS Conservation Practice Standard, Code 380, 

Windbreak/Shelterbelt Establishment, amended 

R18-2-610 (65), in the definition for “wind barrier,” 

to ensure a vegetative wind barrier is sufficiently 

December 21, 2015 Final 69
Test Method Location in the rule and purpose

through August 21, 2009 sufficient to change the pattern of air flow over the 

land surface to control PM emissions, if choosing this 

BMP for noncropland, commercial farm roads (high 

risk days), or cropland

Silt Content Test Method Appendix 2, Subsection (N), incorporated into R18-2-

610 (51), 

6.1.6.2 CAFOs

6.1.6.2.1 Authority

The Agricultural BMP Committee has the statutory authority to adopt the Agricultural BMP 

crops rules under A.R.S. § 49-457(H). Under A.R.S. §§ 49-457(I), (J), and (K), ADEQ has the 

statutory authority to enforce a regulated person’s compliance with the rules and general 

permit program. ADEQ has additional enforcement authority under A.R.S. §§ 49-460, -461, -

462, -463, and -464, which ADEQ will resort to if measures taken under A.R.S. §§ 49-457(I), (J), 

and (K) are unsuccessful to return a facility to compliance. 

6.1.6.2.2 Rule Applicability

The animal operations rules apply to commercial animal operators who engage in regulated 

agricultural activity in the Pinal County PM Nonattainment Area. A commercial farmer is an 

individual, entity, or joint operation in general control of a:

1. commercial dairy operation with more than 150 dairy cattle with the nonattainment 

boundary, 

2. commercial beef feedlot with more than 500 beef cattle within the nonattainment 

boundary, 

3. commercial poultry facility with more than 25,000 egg laying hens within the 

nonattainment area, and/or 

4. commercial swine facility with more than 50 animal units for more than 30 consecutive 

days within the nonattainment area. 

“Regulated activity” upon such operations would be those activities or sources statutorily 

defined in A.R.S. § 49-457(P), consisting of earthmoving activities and one of the categorical

CAFO practices related to: unpaved access connections, unpaved roads or feed lanes, animal 

waste handling and transporting, arenas, corrals, and pens.

6.1.6.2.3 Exemptions or Additional Requirements

Those operations or operator exempted from this rule are those that fall outside of the 

applicable animal population thresholds listed above. There are more specific requirements, 

however, for some animal operations on high risk days. On a high risk day, commercial dairy 

operations within Pinal County shall apply and maintain one of the listed BMPs on unpaved 

roads that experience more than 20 vehicle trips per day from two or more axle vehicles. Beef 

feedlots must also add three to six gallons of water per head of cattle per day to cattle occupied 

pen surfaces.

December 21, 2015 Final 70
6.1.6.2.4 Alternative Practices

An operator may develop different practices to choose as BMPs to control PM emissions, but 

such practices will not be effective until they are submitted as a SIP revision to the EPA per 

A.R.S. § 49-457(L). As provided by A.A.C. R18-2-611.03(K), any alternative practices must be 

“proven effective through on-operation demonstration trials to the Committee.” The already 

statutorily stated purpose of BMPs is to reduce PM10 emissions. Therefore, before submittal, 

any alternative practices would be thoroughly evaluated on a case-by-case basis by the 

Agricultural BMP Committee, and ADEQ would provide technical input and any other advice, as 

needed, to ensure the newly developed practice is sufficiently effective to control PM10. 

6.1.6.2.5 Notice

The definitions and rule requirements are sufficiently clear so as to put the regulated public on 

notice. Where needed, many definitions rely on specific test methods and are extremely 

detailed. ADEQ and the Agricultural BMP Committee have worked together to ensure that the 

rule is clear and understandable. The West Pinal County applicable commercial farms rule is 

more comprehensive and specific than the previous Maricopa rule, which has been in place for 

several years in its current and modified forms.

113

As far as outreach is concerned, the Agricultural BMP statute that establishes the Agricultural 

BMP Committee requires the Committee to develop and commence an education program.114

The Agricultural BMP Committee has been working fervently to develop a program for the Pinal 

nonattainment area community. The outreach developed thus far is very thorough and 

informative. The Committee has created a guidebook, specific to this rule, to help the 

regulated public understand the new standards. There will likely be information in the 

guidebook, also, explaining how to sign up for the high risk forecast, which is critical to the 

rule’s effectiveness. The Committee intends to supply these extensive informational 

guidebooks to the regulated public to ensure compliance with the rule by the compliance date. 

Additionally, the Committee, ADEQ, and the Department of Agriculture have been working to 

develop a comprehensive 3-year survey for each animal operations type, as required by the 

rule. 

6.1.6.2.6 Compliance Schedule

As previously stated, per the Agricultural BMP statute as revised, A.R.S. § 49-457, “[a] person 

who commences a regulated agricultural activity shall immediately comply with the agricultural 

general permit [prescribed by the statute].” Immediate compliance, in this case, would be after 

December 31, 2015, beginning January 1, 2016, as required by the animal operations rule. 

113 See generally, Approval and Promulgation of Maricopa PM-10 Arizona Implementation Plan, 66 FR 51869 (Oct. 

11, 2001).

114 A.R.S. § 49-457(M) (2015).

December 21, 2015 Final 71

 
6.1.6.2.7 Records 

A General Permit Record Form must be filled out and kept as a record onsite and made 

available for review within two business days of notice. The requirements for the record form 

are listed in A.A.C. R18-2-611.03(H), and shall include notation of the categorical BMPs an 

animal operator has chosen to apply on a regular basis and on high risk days, as applicable. 

Such form shall also include a notation of any changes. The purpose of the record form is to 

assist inspectors with enforcement and to hold facilities accountable for their BMPs chosen. 

Beginning in January 1, 2016, a commercial animal operator must maintain records 

demonstrating compliance with the rules for three years, including a copy of the BMP Program 

General Permit Record Form. Additionally, by January 31, 2018, operators must submit their 

first BMP 3-Year Survey which reflects the BMPs chosen in the previous calendar year. The next 

due date after January 31, 2018, will be January 31, 2021 (reporting on 2020), and every three 

years thereafter. The required information is listed in A.A.C. R18-2-611.03(I), and will ensure 

that facilities are held accountable for the required BMPs and will ensure that facilities are held 

accountable for the required BMPs and will also provide ADEQ with the necessary information 

for future emissions calculations.

6.1.6.2.8 Test methods and Compliance

Compliance is determined by inspection and records review. ADEQ will enforce the rule as 

necessary and as authorized, but its primary goal will be to ensure ADEQ takes advantage of 

every opportunity to provide compliance assistance to prevent any violations. Preventing 

violations is the most effective form of protection of human health and the environment. The 

agricultural community is very close-knit in Arizona and has complex needs. Inspectors are 

linked by cell phone to instant monitor alerts, even in the middle of the night. ADEQ’s 

compliance section is extremely responsive to such alerts and any complaints. ADEQ responds 

to such alerts and complaints with contact and/or an inspection of the problem area, in 

addition to regular monthly inspections of various agricultural facilities according to internal 

goals.

Test methods are listed in Table 6-2 below.

Table 6-2 CAFO Rule Test Methods

Test Method Location in the rule and purpose

NRCS Conservation Practice Standard, Code 

380, Windbreak/Shelterbelt Establishment, 

amended through August 21, 2009

R18-2-611 (2)(x) or (3)(r), the equivalent

definitions for “wind barrier,” to ensure a 

vegetative wind barrier is sufficiently sufficient 

to change the pattern of air flow over the land 

surface to control PM emissions, if choosing this 

BMP for control of arenas, corrals, and pens, at a 

dairy operation of a commercial beef lot control, 

or to control unpaved roads or feed lanes at 

swine operations, 

December 21, 2015 Final 72
6.1.6.3 Irrigation Districts

6.1.6.3.1 Authority

The Agricultural BMP Committee has the statutory authority to adopt the Agricultural BMP 

crops rules under A.R.S. § 49-457(H). Under A.R.S. §§ 49-457(I), (J), and (K), ADEQ has the 

statutory authority to enforce a regulated person’s compliance with the rules and general 

permit program. ADEQ has additional enforcement authority under A.R.S. §§ 49-460, -461, -

462, -463, and -464, which ADEQ will resort to if measures taken under A.R.S. §§ 49-457(I), (J), 

and (K) are unsuccessful to return a facility to compliance. 

6.1.6.3.2 Rule Applicability

The irrigation district rules apply to irrigation districts within a PM Nonattainment Area 

designated after June 1, 2009 (including the West Pinal Nonattainment area), that engage in 

regulated agricultural activity in the Pinal County PM Nonattainment Area. An irrigation district 

is a political subdivision governed by A.R.S. Title 48, Chapter 19, Irrigation and Water 

Conservation Districts, and per A.R.S. § 48-2901, all such subdivisions are declared municipal 

corporations for all purposes.

“Regulated activity” by such districts would be regulating those activities or impact of sources 

as statutorily defined in A.R.S. § 49-457(P), which are only under the jurisdiction and control of 

the district, including regulating practices related to unpaved operation and maintenance 

roads, canals, and unpaved utility access roads. 

6.1.6.3.3 Exemptions or Additional Requirements

Those operations or operator exempted from this rule are those that fall outside of the 

applicable requirements, including jurisdiction, listed above. There are no additional 

requirements on high risk days.

6.1.6.3.4 Alternative Practices

A district may develop different practices to choose as BMPs to control PM emissions, but such 

practices will not be effective until they are submitted as a SIP revision to the EPA per A.R.S. § 

49-457(L). As provided by A.A.C. R18-2-612.01(E), any alternative practices must be “proven 

effective through on-operation demonstration trials to the Committee.” The already statutorily 

stated purpose of BMPs is to reduce PM-10 emissions. Therefore, before submittal, any 

alternative practices would be thoroughly evaluated on a case-by-case basis by the Agricultural 

BMP Committee, and ADEQ would provide technical input and any other advice, as needed, to 

ensure the newly developed practice is sufficiently effective to control PM10. 

6.1.6.3.5 Notice

The definitions and rule requirements are sufficiently clear so as to put the regulated public on 

notice. Where needed, many definitions rely on specific test methods and are extremely 

December 21, 2015 Final 73
detailed. ADEQ and the Agricultural BMP have worked together to ensure that the rule is clear 

and understandable. 

6.1.6.3.6 Compliance Schedule 

As previously stated, per the Agricultural BMP statute as revised, A.R.S. § 49-457, “[a] person 

who commences a regulated agricultural activity shall immediately comply with the agricultural 

general permit [prescribed by the statute].” Immediate compliance, in this case, would be after 

December 31, 2015, beginning January 1, 2016, as required by the irrigation districts rule. 

6.1.6.3.7 Records 

A General Permit Record Form must be filled out and kept as a record onsite and made 

available for review within two business days of notice. The requirements for the record form 

are listed in A.A.C. R18-2-611.03(H), and shall include notation of the categorical BMPs an 

irrigation district has chosen to apply on a regular basis. Such form shall also include a notation 

of any changes. The purpose of the record form is to assist inspectors with enforcement and to 

hold facilities accountable for their BMPs chosen. 

Beginning January 1, 2016, an irrigation district must maintain records demonstrating 

compliance with the rules for three years, including a copy of the BMP Program General Permit 

Record Form. Additionally, by January 31, 2018, districts must submit their first BMP 3-Year 

Survey which reflects the BMPs chosen in the previous calendar year. The next due date after 

January 31, 2018, will be January 31, 2021 (reporting on 2020), and every three years 

thereafter. The required information is listed in A.A.C. R18-2-611.03(I), and will ensure that 

districts are held accountable for the required BMPs and will also provide ADEQ with the 

necessary information for future emissions calculations.

6.1.6.3.8 Test methods and Compliance

Compliance is determined by inspection and records review. ADEQ will enforce the rule as 

necessary and as authorized, but its primary goal will be to ensure ADEQ takes advantage of 

every opportunity to provide compliance assistance to prevent any violations. Preventing 

violations is the most effective form of protection of human health and the environment. The 

agricultural community is very close-knit in Arizona and has complex needs. Inspectors are 

linked by cell phone to instant monitor alerts, even in the middle of the night. ADEQ’s 

compliance section is extremely responsive to such alerts and any complaints. ADEQ responds 

to such alerts and complaints with contact and/or an inspection of the problem area, in 

addition to regular monthly inspections of various agricultural facilities according to internal 

goals.

Applicable test methods are listed in Table 6-3 below.

Table 6-3 Irrigation Districts Rule Test Methods

Test Method Location in the rule and purpose

NRCS Conservation Practice Standard, Code 380, 

Windbreak/Shelterbelt Establishment, amended 

R18-2-612 (33), in the definition for “wind 

barrier,” to ensure that the vegetative barrier is 

December 21, 2015 Final 74
through August 21, 2009 sufficient to change the pattern of air flow over 

the land surface to control PM emissions

December 21, 2015 Final 75
6.1.7 Credited Annual Emission Reductions from Agricultural BMP 

Rules

Table 6-4 Agricultural Best Management Practices Rule Reductions 

(Attainment and Contingency)

Attainment Contingency

AgBMP 

Rule 

Subtotal

Unpaved 

crop 

farm 

roads

Unpaved 

canal 

O&M 

roads

Harvesting 

and Tilling CAFOs Dairies

Windblown dust

Unpaved Roads 705.2 144.7 849.9

Dairies

(including 

unpaved roads)

65.4 65.4

CAFOs

(including 

unpaved roads)

29.9 29.9

Agriculture 12,388.1 12,388.1

Subtotal 705.2 144.7 12,388.1 29.9 65.4 13,333.3

Activity-based emissions

Ag Fields -

Harvesting 105.8 105.8

Ag Fields -

Tilling 882.3 882.3

CAFOs 251.4 251.4

Unpaved Road 7,341.3 577.6 7,918.8

Dairy 35.8 35.8

Subtotal 7,341.3 577.6 988.1 251.4 35.8 9,194.2

Total 8,046.5 722.3 13,376.2 281.3 101.2 22,527.5

December 21, 2015 Final 76
6.2 Fugitive dust – Contingency Measure

6.2.1 Fugitive Dust Rule Summary

This rule is a general area source control rule, not permit based. Owners and/or operators of 

several source types are subject to implement required PM10 control measures on applicable 

sources to meet visible emissions and stabilization requirements, in order to reduce PM 

emissions in the West Pinal Nonattainment Area. Open areas/vacant lots of a particular 

threshold must be stabilized to 20% opacity for fugitive emissions on the property, and 

owners/operators must install and maintain trespassing signs or physical barriers if trespass 

occurs on the property. Within 30 days following the discovery of the threshold disturbed 

surface area, the owner/operator shall sign up to receive ADEQ’s Pinal County Dust Control 

Forecast (i.e. high risk forecast) and shall ensure the lot is stabilized the day leading up to and 

the day of high risk forecast. Unpaved lots of a particular size threshold must be controlled to 

meet opacity and stabilization requirements. Unpaved roads above 150 Average Daily Trips 

(ADT) are subject to specific opacity and stabilization (silt loading/content) standards, and 

owners/operators must incrementally control a specific length of such unpaved roads. Paved 

public roadways are subject to trackout clean up and taking stabilization actions before, during 

and after work on unpaved road shoulders along paved public roadways.

6.2.2 Planned Rule Implementation Schedule – General Fugitive Dust 

Rule

The Pinal County Air Quality Control District filed the rule with the Secretary of State. The rule 

was published in the Arizona Administrative Register as a final rule, effective January 1, 2016.115

The hearing/Board of Supervisors meeting took place on October 28, 2015. Pinal County 

provided ADEQ with its rulemaking documentation to submit to the EPA.116 

6.2.3 Enforceability

6.2.3.1 Authority

Per A.R.S. 49-479(A), the Pinal County Board of Supervisors has specific authority, subject to 

procedural requirements, to adopt and implement rules to control the atmospheric release of 

air contaminants originating within the Pinal County territorial limits. Pinal County may adopt 

rules that are more stringent than ADEQ’s as long as certain conditions are met such as the rule 

is necessary to address a peculiar local condition and there is credible evidence that the rule is 

either: (1) necessary to prevent significant threat to public health or the environment and the 

rule is technically and economically feasible, or (2) the rule is required under federal statute or 

regulation. ADEQ has no similar construction permit, therefore the permit and authorizing rule 

115 See Appendix I; see also Exhibit G-VIII. 116 See Appendix I.

December 21, 2015 Final 77

 
are more stringent than ADEQ’s rules. However, this rule is federally required per C.A.A. §189, 

insofar as to ensure that ADEQ is able to submit a SIP on behalf of Pinal County for the West 

Pinal County moderate nonattainment area, and that there are rules in place to control PM 

emissions for a significant dust generating sources of general fugitive dust, particularly unpaved 

roads.

Per A.R.S. 49-473, the Board of Supervisors additionally has authority to authorize Pinal County 

Air Quality District to carry out the necessary investigations, inspections, and enforcement of 

any rules adopted pursuant to prevailing statutory authority. Such prevailing statutory 

authority includes those defining violations and processes for violation consequences, such as 

A.R.S. §§ 49-502, -510, -511, -513, and -514.

6.2.3.2 Rule Applicability

The Fugitive Dust rule applies to owners/or operators of dust emitting sources such as open 

areas/vacant lots, unpaved roads, unpaved lots, and paved public roadways to control PM 

emissions from such sources located within the West Pinal Nonattainment Area and activities 

upon such sources. Regulated sources requiring control measures are those above applicable 

thresholds as follows:

1. open areas, public or private, of 1.0 acre or larger that have 0.5 acres or more of 

disturbed surface area

2. unpaved lots 5,000 ft2 or larger in size

3. unpaved public roads with 150 Average Daily Trips (ADT)

4. paved public roadways with trackout that extends 50 feet or more

5. paved public roadway shoulders

6.2.3.3 Exemptions or Additional Requirements

Anything below the thresholds listed above is not subject to stabilization or control

requirements under this rule.

6.2.3.4 Alternative Practices

Alternative measures that are adequate to address a work site’s applicable standards in 

PCAQCD Code § 4-3-180 must be approved by PCAQCD and the EPA Administrator.

6.2.3.5 Notice

The definitions and rule requirements are sufficiently clear so as to put the regulated public on 

notice. Pinal County has worked closely with industry representatives to ensure the rule is 

understandable and clear so that the regulated can comply with it. Regulated government 

entities (owners/operators of several public roads), Pinal County, and ADEQ have consulted 

with one another to ensure understanding of the rule as written. Pinal County and ADEQ also 

intend to conduct outreach to ensure the regulated public is informed of the rule, its 

requirements, and how to sign up for the high risk forecast. Where needed, the rule relies on 

specific test methods to ensure compliance.

December 21, 2015 Final 78
6.2.3.6 Compliance Schedule 

Per the language of the rule, it will be effective as of January 1, 2016. From that point on, the 

regulated community must comply with the rule. 

6.2.3.7 Records 

Any person subject to the Fugitive Dust rule shall compile and retain records that provide 

evidence of control application. Upon notice, such person shall provide the records and 

supporting documentation as soon as possible but no later than 48 hours to Pinal County. 

Additionally, each city, county, or state agency with primary responsibility for existing paved 

public roadways and unpaved roads shall provide the Pinal County with a list of all unpaved 

roads, including data of the length of and ADT on, unpaved roadways in its jurisdiction by 

January 30th of each year. Additionally, by January 30 of each year, each entity as previously 

described shall submit to the District a list of unpaved roads paved within the previous year, 

along with their respective ADTs and mileage. Copies of records and reporting shall be retained 

for at least two years.

6.2.3.8 Test methods and Compliance

Compliance is determined by inspection and records review. Failure by any person to comply

with the requirements of the rule is a violation and such person is subject to Pinal County’s 

authority to enforce, as listed above. In particular, in the case that any owner and/or operator 

of unpaved roads with ADT greater than 150 do not comply with applicable requirements, 

including paving, applying dust suppressants other than water, or applying gravel on 15 miles of 

roads above 150 ADT (or the equivalent from 2019 and beyond), each owner/operator shall be 

subject to enforcement. All owners/operators shall be held jointly and severally liable, 

regardless of the efforts made by one entity over others. For example, if Entity A paves 14 miles 

in one year, but none of the other owners/operators apply (and maintain, if necessary) any of 

the listed control measures for the same year, then all owners/operators, including Entity A, are 

subject to enforcement. All parties in that case would be held responsible for the road control 

deficiency violation. It is up to all the owners/operators within the West Pinal Nonattainment 

area to demonstrate compliance with this rule.

As a practical matter, the stabilization of unpaved roads in the West Pinal PM10 Nonattainment 

Area is coordinated between several entities including Pinal County Public Works; the Sun 

Corridor MPO and member cities and towns including Casa Grande, Eloy, Coolidge, and Pinal 

County; Maricopa Association of Governments and member city and towns including Maricopa 

and Queen Creek, and Pinal County. Coordination efforts are achieved through regular MPO 

meetings, development of transportation improvement plans (TIP’s) incorporating additional 

stabilization requirements, and interagency coordination with respect to planning and 

budgetary needs.

Applicable test methods are listed in Table 6-5 below.

December 21, 2015 Final 79
Table 6-5 General Fugitive Dust Rule Test Methods

Test Method Location in the rule and purpose

Opacity (as applicable from PCAQCD code §4-9-

340)

§ 4-1-130.2.A, and 3.A.i, 4.A.i, and 5.A.i.ii, in the 

control requirements for measuring fugitive dust 

from the applicable open areas/vacant lots, 

unpaved lots, unpaved roads, and paved public 

roads, respectively, by measuring and ensuring 

opacity is below 20%

Visible Crust Determination [The Drop Ball Test] 

as defined in PCAQCD Code § 4-9-329.B.1

§ 4-1-130.2.F.i, to ensure control measures 

implemented ensure surface crusting is resistant 

to wind-driven fugitive dust

Threshold Friction Velocity as determined by 

test method in PCAQCD Code § 4-9-320.B.2

§ 4-1-130.2.F.ii, to determine the threshold 

friction velocity of disturbed surface areas that 

are not crusted or vegetated

NRCS Conservation Practice Standard, Code 380, 

Windbreak/Shelterbelt Establishment, amended 

through August 21, 2009Determination of Flat 

Vegetative Cover, PCAQCD Code §4-9-320.B.3 

R18-§ 4-1-130.2-612 (33), in the definition for 

“wind barrier,”.F.iii, to ensure that the flat 

vegetative barrier is sufficient to change the 

pattern of air flow over the land cover (rooted or 

unattached vegetative debris lying on the surface 

with a predominant horizontal orientation that is 

not subject to movement by wind) equals at least 

50% to meet the applicable control PM emission

control measure requirement

Determination of Standing Vegetative Cover, 

PCAQCD Code §4-9-320.B.4 

§ 4-1-130.2.F.iii and F.iv, to ensure the standing 

vegetative cover (rooted vegetation with a 

predominant vertical orientation)meets minimum 

percent coverage requirements, depending on 

the control measure and applicable threshold 

friction velocity

Silt Content Test Method for Unpaved Roads and 

Unpaved Parking Lots, in PCAQCD Code § 4-9-320.A.1

§ 4-1-130.3.A.i, and 4.A.i, to test whether silt 

loading is equal to or greater than 0.33 oz/ft2 on 

unpaved lots and unpaved roads, respectively, 

and if equal or greater, to evaluate the percent 

silt content

December 21, 2015 Final 80
6.2.4 Credited Annual Emissions Reductions from Fugitive Dust Rule

Table 6-6 Fugitive Dust Rule Attributable Annual Inventory Reductions (TPY) 117

Vacant 

lots and 

open areas

Unpaved 

lots

Unpaved 

public 

roads

Paved 

road 

shoulders

Fugitive 

Dust Rule 

Subtotal

Windblown dust emissions

Developed 

Urban Lands 33.8 14.1 0.5 48.4

Developed Rural 

Lands (low density 

residential) 25.6 33.6 1.2 60.4

Unpaved Roads 9.4 9.4

Cleared Areas 114.4 16.7 0.1 131.2

Desert 

Shrubland 1,554.2 3.2 1,557.4

Other 1.8 1.8

1,727.9 64.4 7.1 6.8 1,808.5

Activity-based emissions

Paved Road 0.8 0.8

Unpaved Road 1,033.3 1,033.3

Unpaved 

Parking 79.1 79.1

Subtotal 79.1 1,133.3 0.8 1,213.2

1,727.9 143.4 1,142.7 7.6 3021.7

117 This chart does not reflect the actual reductions in trackout emissions from the fugitive dust rule. In the 

construction rule’s credited reductions, the reductions from trackout rule provisions actually reflect reductions 

from a combination of both the construction and fugitive rules. The creditable emissions were never numerically 

separated to attribute the respective reductions to each rule.

December 21, 2015 Final 81

 
6.3 Construction Rule - Contingency

6.3.1 Construction Rule Summary

The Pinal County Fugitive Dust Construction Rule (Construction Rule) is a permit based 

program. Prior to engaging in any dust generating operations an owner and/or operator shall 

file a dust generating application and receive a signed permit from Pinal County. Different 

requirements apply depending on the size of the work site. All works sites must at least meet a 

20% opacity standard for dust generating operations and ensure stabilization using all 

applicable control measures, including watering before and during operations, applying 

chemical dust suppressants, altering load-in/load-out procedures and watering, reducing 

vehicular speeds, controlling freeboard and spillage and covering haul vehicles, trackout control 

device, limiting, restricting or rerouting motor vehicles and other measures.

6.3.2 Planned Rule Implementation

The Pinal County Air Quality Control District filed the rule with the Arizona Secretary of State.

The hearing/Board of Supervisors meeting to adopt the rule took place on October 28, 2015. 

The rule was published in the Arizona Administrative Register as a final rule, effective January 1, 

2016.

118 Pinal County provided ADEQ with its rulemaking documentation to submit to the 

EPA.

119

6.3.3 Enforceability

6.3.3.1 Authority

Per A.R.S. 49-479(A), the Pinal County Board of Supervisors has specific authority, subject to 

procedural requirements, to adopt and implement rules to control the atmospheric release of 

air contaminants originating within the Pinal County territorial limits. Pinal County may adopt a 

rule that is more stringent than ADEQ’s as long as certain conditions are met. Such conditions 

include that the rule is necessary to address a peculiar local condition and there is credible 

evidence that the rule is either: (1) necessary to prevent significant threat to public health or 

the environment and the rule is technically and economically feasible, or (2) the rule is required 

under federal statute or regulation. ADEQ has no similar construction permit. Therefore, the 

permit and authorizing rule are more stringent than ADEQ’s rules. However, this rule is 

federally required per C.A.A. §189, insofar as to ensure that ADEQ is able to submit a SIP on 

behalf of Pinal County for the West Pinal County moderate nonattainment area, and that there 

are rules in place to control PM emissions for a significant dust generating source such as 

construction work sites and associated activity. 

118 See Appendix H; see also Exhibit G-VII.

119 See Appendix H.

December 21, 2015 Final 82

 
Per A.R.S. 49-473, the Board of Supervisors additionally has authority to authorize Pinal County 

Air Quality District to carry out the necessary investigations, inspections, and enforcement of 

any rules adopted pursuant to prevailing statutory authority. Such prevailing statutory 

authority includes those defining violations and processes for violation consequences, such as 

A.R.S. §§ 49-502, -510, -511, -513, and -514.

6.3.3.2 Rule Applicability

Pinal County’s West Pinal PM10 Nonattainment Area Construction Fugitive Dust rule applies to 

construction activities generating fugitive dust in the West Pinal PM10 nonattainment area. 

Construction, as used in the rule, means building, maintaining, or modifying a capital 

improvement resting upon, connected to, or buried in the earth.

Different requirements apply to different sized work sites. Work sites 0.1 acres or larger must 

meet a 20% opacity standard and stabilization requirement. Work sites 5 acres or larger must 

install a trackout device, erect signs or barriers to limit trespass in areas where dust generating 

operations have ceased for more than 30 days, and ensure the work site is stabilized the day 

leading up to and the day forecast to be high risk. 

6.3.3.3 Exemptions or Additional Requirements

Exemptions from the rule include permit requirements for facilities operating under an 

industrial permit, as well as road maintenance activities (these activities are however subject to 

applicable standards), emergency repair of activities (these do not require an application or 

permit), pitched rooftop tile operations, vehicle test and development facilities, nonmechanically adjusted initial landscapes, and in case of an emergency, stabilization actions can 

be taken before submitting a permit. There is also an exemption from the opacity standard in 

high wind conditions, if the applicable control measures requirements were sufficiently

implemented so that disturbed areas are stabilized and one of the following is met: (1) the 

facility ceases operating until opacity requirements are no longer exceeded or (2) maintain 

documentation that the continued dust generating operations are not contributing to the 

opacity violation. Such documentation may include onsite opacity observations by a certified 

observer.

6.3.3.4 Alternative Practices

A regulated registrant may propose other control measures not specifically listed, as long as the 

alternative measures are approved by the director of Pinal County Air Quality Control District 

and the EPA Administrator.

6.3.3.5 Notice

The definitions and rule requirements are sufficiently clear so as to put the regulated public on 

notice. Pinal County has worked closely with industry representatives to ensure the rule is 

understandable and clear so that the construction industry can comply with it. Industry 

representatives, Pinal County, and ADEQ intend to conduct outreach to ensure the regulated 

December 21, 2015 Final 83
construction entities are informed of the rule and how to sign up for the high risk forecast. 

Where needed, the rule relies on specified test methods to ensure compliance.

6.3.3.6 Compliance Schedule 

Per the language of the rule, the construction rule will become effective January 1, 2016. From 

that point on, the regulated community must comply with the rule. T 

6.3.3.7 Records 

An owner/operator of a work site shall maintain a copy of his signed permit and shall keep 

records of every other week inspections and an owner/operator of a work site 5 acres or larger 

shall also keep records of his site-wide inspection reports for the day leading up to and of the 

day forecast to be high risk. Upon notice, an owner/operator shall provide Pinal County with 

inspection records as soon as practicable, but no later than 72 hours from the verbal or written 

notice. The owner/operator shall notify Pinal County of project completion no later than 30 

days after completion date. Owners/operators of work sites five acres or larger shall post a 

project information sign at the work site main entrance, visible to the public.

6.3.3.8 Test methods and Compliance

Compliance is determined by inspection and records review. Failure by any person to comply 

with the requirements of the rule is a violation and such person is subject to Pinal County’s 

authority to enforce, as listed above. Applicable methods are listed in Table 6-7 below.

Table 6-7 Construction Rule Test Methods

Test Method Location in the rule and purpose

Visible Crust Determination [The Drop Ball Test] 

as defined in PCAQCD Code § 4-9-329.B.1

§ 4-3-170(21), in the definition for “stabilize,” to 

ensure surface crusting is resistant to wind-driven 

fugitive dust

Applicable Opacity Test Method as defined in 

PCAQCD Code § 4-9-340

§ 4-3-180(A), in the recordkeeping requirements 

to ensure that work sites do not conduct or allow 

dust generating operations to result in opacity 

exceeding 20%

6.3.4 Credited Annual Emissions Reductions

Those emissions reductions attributable to emissions reductions credited from the Construction 

Rule are listed in Table 6-8 below.

Table 6-8 Annual Inventory Reductions Attributable to Construction Rule (TPY)

ADEQ estimated the following 

emissions reductions based on 2018 

assumptions (e.g., that 30 miles of 

unpaved road controls are in place, 

implemented in 2016 and 2017).

Trackout All other 

provisions

Construction 

Rule Subtotal

December 21, 2015 Final 84
Windblown dust 

Residential 

Construction 407.0 407.0

Commercial 

Construction 225.1 225.1

Site Development 273.3 273.3

Subtotal 905.4 905.4

Activity-based 

emissions

Paved Road 5.0120 5.0

Construction 3,781.3 3,781.3

Subtotal 5.0 3,781.3 3,786.2

Total 5.0 4,686.64 4,691.6

6.4 Statutory Amendments 

6.4.1 Agricultural Best Management Practices - Arizona Revised 

Statutes (A.R.S.) § 49-457

The statute establishing agricultural best management practices committee was revised in April 

2015. The statute has previously been submitted and approved as a part of the SIP, and the 

most recent revisions provide key assurances that facilities will immediately implement the 

BMPs as mandated under the applicable rules. 

The unrevised version of the statute was first submitted on September 4, 1998 and approved 

on June 17, 1999.121 The statute as revised is effective from and after January 1, 2016, which is 

the applicable implementation date of the rules.122 The revisions since original approval are 

various and some important revisions include:

1. The Agricultural BMP Committee expanded its size by increasing number of industry 

representatives,

120 This actually reflects reductions in trackout emissions from a combination of both the construction and fugitive 

rules, but this number was never numerically separated to attribute the respective reductions to each rule. 121 See generally, Approval and Promulgation of Arizona-Maricopa PM-10 Nonattainment Area Implementation 

Plan, 64 FR 34726, 34732 (Jun. 29, 1999)

122 See, Exhibit G-IV: A.R.S. §49-457 (2015) (effective Jan. 1, 2016); see also Exhibit GIII-1 for House Bill 2394, 

Amending A.R.S. § 49-457 (Fifty-second Legislature, First Regular Session, 2015, Chapter 243, § 1).

December 21, 2015 Final 85

 
2. A person engaged in agricultural activity (in a regulated area) shall immediately comply 

with the agricultural general permit, immediate compliance being effective January 1, 

2016,

3. The best management practices general permit must include recordkeeping and 

reporting requirements,

4. Best management practices and the ensuing program is effective in any nonattainment 

area for PM10 established after June 1, 2009,

5. Identification of specifically regulated areas within commercial farms and animal 

operations, as well as earthmoving activities on commercial farms,

6. A provision to regulate irrigation districts (irrigation and water conservation districts) 

and their respective sources of PM, and

7. A more specific definition of regulated agricultural activities and regulated area.

6.4.2 High Risk Forecast - Arizona Revised Statutes (A.R.S.) § 49-

424(11)

ADEQ has the primary duty to flag high risk forecasts for the West Pinal nonattainment area. 

The ADEQ, Air Quality, Assessment Section then sends out a mass mailing each day informing 

the public, through Govdelivery.com, as to whether the day is high risk for PM10 or not. When 

developing forecasts, ADEQ evaluates several factors including projected meteorological 

conditions, existing concentrations of air pollution at the time of the forecast, and historic air 

pollution concentrations that have been observed during meteorological conditions similar to 

those predicted in the forecast. Meteorological conditions considered include wind speed and 

direction, stagnation, recent and potential for precipitation.

Since A.R.S. § 49-424 was last submitted and approved into the SIP,

123 the high risk forecast 

section (Section 11) was revised in 2014 to mandate air quality dust forecasts for any other 

PM10 nonattainment or maintenance area designated in Arizona after December 31, 2011, in 

addition to forecasts for the Maricopa County PM10 nonattainment area.

The statute is referred to in all three of the rule schemas submitted for EPA’s review. 

6.5 Adequate Resources124

6.5.1 Adequate Resources – Agricultural Rules

The costs of the rulemaking to ADEQ and Arizona Department of Agriculture (ADA) will be 

minimal. ADA is included in this adequate resources discussion because ADA is prescribed 

duties in the rule.

123 Partial Approval and Disapproval of Arizona PM Implementation Plan, 77 FR 66398 (November 5, 2012). 124 See, C.A.A. § 110(a)(2)(E)(i); 40 C.F.R. § 51.280.

December 21, 2015 Final 86

 
ADA and ADEQ will have to expend time and monetary resources for revising and printing new 

guidebooks and for education. ADEQ and ADA staff will have to expend time learning the new 

rules and ADEQ will have to revise its compliance strategies to implement the rules. ADEQ 

estimates that the current number of full time employees assigned in Compliance Section of the 

Air Quality Division is adequate to implement and enforce the new rules. ADEQ does enforce 

agricultural rules throughout the state. However, ADEQ intends to prioritize and focus, at least 

preliminarily and as needed, on agricultural enforcement in West Pinal County to ensure that 

ADEQ provides the assistance, education, and enforcement necessary to carry out the rules to 

reach attainment in the nonattainment area. 

ADEQ expects the new recordkeeping costs associated with this rulemaking to be minimal, as 

the forms have changed minimally, and although they must be turned in to the ADA, it is still 

undecided if postage can be covered by ADEQ, ADA, or an electronic delivery system could be 

put into place. ADEQ is still developing the survey forms that will be due in 2018 to report on 

the 2017 year. Additionally, ADEQ and ADA will have to spend time and resources to compile 

data from the submitted three year surveys. Of the recordkeeping costs, this would require the 

most time and expense.

Overall, ADEQ expects the financial impact of the additional rules to be minimal, even though 

the rule imposes an administrative burden on the enforcement agency and on the ADA for 

collection of forms. The general permit that is credited as part of these rules is not fee based, 

and therefore, the cost of resources will be covered through the use of other budgetary 

resources at both agencies. ADEQ’s program should be effectively handled by its current 

personnel without any additional staffing or resources requirements. ADEQ has a sufficient 

budget to support the program and commits to support the program at least through the next 5 

years. 

6.5.2 Adequate Resources - Fugitive Dust and Construction Rules 

Fugitive dust inspections, response to citizen complaints, primary oversight of dust permit 

issuance, and enforcement are managed by staff within Pinal County Air Quality Control District 

Field Services. Field Services consist of a manager (half time - split between monitoring and 

compliance), and two field inspectors. Field Services inspectors conduct scheduled inspections 

of permitting activities, complaint-based inspections, and random inspections of observed 

activities. Inspectors average in excess of 40 inspections per month depending on variables 

such as travel time and source complexity. Additionally, a Lead Compliance Engineer placed 

within Pinal County Air Quality Control District Permitting oversees fugitive dust compliance at 

permitted sources through scheduled and unannounced inspections. Over-the-counter 

construction dust permits are issued each day during normal business hours at the main office 

and one day per week at two satellite offices by a rotating assignment of department wide 

staff. During the in-person permit application and issuance process applicants are provided 

guidance for compliance.

The current staffing level has been in place since 2010 coinciding with the slowdown in 

construction activity in Pinal County. Construction projections in the county show a slow to 

December 21, 2015 Final 87
moderate increase over the next 5 years. Projecting 1, 3, and 5 years into the future, Pinal 

County anticipates sustaining the current effort to conduct scheduled inspections of permitted 

dust sources as well as proactive inspections of area dust emissions. With the current level of 

dust permits issued annually, the staffing level will be sufficient in future years.

December 21, 2015 Final 88
7 ATTAINMENT DEMONSTRATION AND REASONABLE 

FURTHER PROGRESS

Effective July 2, 2012, the EPA redesignated the West Pinal area from an unclassifiable area to a 

moderate nonattainment area. This action required Arizona to demonstrate (1) that the plan 

will provide for attainment as expeditiously as practicable but no later than the attainment 

date,

125 or a demonstration that attainment by such date is impracticable,126 and (2) 

quantitative milestones, which demonstrate reasonable further progress (RFP) toward timely 

attainment,127 that are to be achieved every 3 years until the area is redesignated 

attainment.128 

ADEQ has demonstrated attainment no later than December 2018 and has verified sufficient 

annual incremental emission reductions to satisfy reasonable further progress requirements.

7.1 Attainment Demonstration

This section briefly describes the methods for demonstrating and modeling attainment in the 

West Pinal Nonattainment Area, with attainment expected no later than December 2018. 

More specifically, this chapter explains ADEQ’s steps in determining modeling domains and 

methodologies, including how modeling design days were chosen, as well as how the controls 

from the recently revised Agricultural Best Management Practices Committee rules (collectively 

referred to hereinafter as the “AgBMP rules”) were accounted for in the attainment 

demonstration. The West Pinal AgBMP rules, except for the dairy applicable section, are the 

only rules used to demonstrate attainment in this SIP.129 More discussion regarding the AgBMP 

rules themselves can be found in Chapter 6 of this document and also the RACM Document, 

Appendix F.

Inventory analysis showed that two distinct meteorological scenarios produced concentrations 

in excess of the 24-hour PM10 National Ambient Air Quality Standard (NAAQS) of 150μg/m3: 

high wind and stagnation conditions. The emission sources responsible for the elevated 

concentrations are fundamentally different under these two scenarios.

130 Therefore, the two 

meteorological scenarios required the use of different design days, for which monitor-specific 

125 i.e. end of December 2018. See, C.A.A. § 188(c)(1) (2012) (“For a Moderate Area, the attainment date shall be 

as expeditiously as practicable but no later than the end of the sixth calendar year after the area’s designation as 

nonattainment...”). 

126 See C.A.A. § 189(a)(1)(B) (2012). 127 As defined in C.A.A. § 171(1) (2012). 128 See C.A.A. § 189(c)(1) (2012). 129 Emissions reductions resulting from the dairy operations section, A.A.C. R18-2-611.03(D), have been applied 

toward contingency measures instead of attainment. More information on contingency measures is contained in 

Chapter 6 of the SIP main body and Appendix D. 130 See Appendix A (IPP), Section 3.2, p. 50, for more information.

December 21, 2015 Final 89

 
inventories were developed, with separate concentration calculation methodologies utilized for 

high wind and stagnation design days. Differences in source mix and the range of 

meteorological conditions affecting emissions in the area guided the decision to select at least 

one stagnation and one high wind design day for each nonattaining monitor, as applicable per 

exceedance data.131

7.1.1 Stagnation Attainment Modeling Background

7.1.1.1 Stagnation Condition Description

During stagnation periods, when wind speeds are typically below 3 mph, wind entrainment of 

loose soil particles is virtually nonexistent and mechanical sources that lift particles into the air 

through combustion, vehicle movement, and other anthropogenic activities are primarily 

responsible for recorded concentrations. Particles accumulate in the air without any 

meteorological reprieve during stagnation periods. 

7.1.1.2 Stagnation Design Day Selection

After analysis of all stagnation day exceedances in 2008, three monitors exceeded the 24-hour 

PM10 NAAQS. Two days were found to be the most representative after isolating quality 

assured data and noting that there were no high wind speed hours recorded on the selected 

days.132 The meteorological conditions were most representative for the Pinal County Housing 

and Stanfield monitors on October 29, 2008. Cowtown also exceeded on October 30, 2008. 

However, the closure of several significant emission sources near the Cowtown monitor 

between 2008 and 2011 and the continued recording of 24-hour PM10 exceedances at the 

monitor caused a reassessment of the October 29, 2008 design day for that monitor. October 

30, 2008 exhibited similar meteorological conditions and was found to be most representative 

for the Cowtown monitor.133 

The sites and dates for the selected stagnation design days are listed below: 

• Pinal County Housing - October 29, 2008

• Stanfield - October 29, 2008

• Cowtown - October 30, 2008

No PM10 exceedances occurred on stagnation days at the Maricopa, Casa Grande, or Combs 

School monitoring sites, and therefore these monitors were not included in the list of low wind 

speed attainment demonstrations.134

131 See Appendix A (IPP), Section 3.2, p. 50-51, for more information. 132 See Appendix A (IPP), Section 3.2, p. 52, for more information. 133 See generally Appendix B (EI TSD) Section 2.2; see also Exhibit B-XIII. 134 See Appendix A (IPP), Section 3.3, p. 51, Table 3-2.

December 21, 2015 Final 90

 
The closure of several significant emission sources near the Cowtown monitor between 2008 

and 2011 and the continued recording of 24-hour PM10 exceedances at the monitor caused a 

reassessment of the October 29, 2008 design day for that monitor. The resulting analysis, 

presented in Exhibit 12, led to the selection of October 30, 2008 to represent low wind 

conditions at the Cowtown monitor.135

7.1.1.3 Stagnation Domain Boundary Selection

Separate domains were defined for each of the three selected monitors. To define low wind 

domains for the modeling inventories, rectangular boundaries were demarcated based on the 

maximum hourly distance traversed by wind parcels from the monitor to the source.136

Transport distances are relatively short under low wind conditions, therefore only those 

sources within close proximity (varying by monitor’s modeling domain) of a monitor contribute 

to high hourly PM10 concentrations during stagnation conditions.137

The Cotton Research and Protection Council (CRPC) characterized crops under cultivation in 

2008 for a 6 km radius (3.7 mi) surrounding the nonattaining monitors of Cowtown, Maricopa, 

Pinal County Housing, and Stanfield. CRPC data did not include characterization of crop lands 

outside of this 6 km boundary or Indian Reservation crop lands. Assumptions for nonidentified 

agricultural lands and additional sources on Gila River Indian Community and AK-Chin land, 

such as unpaved roads and point sources are described in Section 3.1.1.13 of Appendix B (EI 

TSD).

7.1.1.4 Stagnation Model Method Selection - AERMOD

After review of EPA guidelines and fugitive dust modeling demonstration in MAG plans, ADEQ 

decided that AERMOD is the most suitable model for evaluating hourly source contributions to 

PM10 exceedances recorded at Pinal County monitors on stagnation design days. AERMOD, a

steady-state Gaussian plume dispersion model that assesses pollutant concentrations from a 

variety of source types, is very effective for predicting emissions during near calm conditions.138 

On stagnation days, AERMOD was run with meteorological data recorded at the subject 

monitor and emissions rates for each source within the modeling domain, as calculated from 

reported activity data and best-representative emissions factors.139 A domain specific average 

emissions rate was computed for the crops included within the CRPC domains and was applied 

to each agricultural crop parcel in the tribal domain. Small portions of the modeling domains 

fall outside of the CRPC boundary so assumptions about crop activity on agricultural lands 

outside the boundary were needed.140

135 See generally Appendix B (EI TSD), Section 2.2. 136 See generally Appendix B (EI TSD), Section 1.1. 137 See generally Appendix A (IPP), Section 3.2. 138 See generally Appendix C (Modeling TSD), Section 2. 139 Appendix C (Modeling TSD), p. 2. 140 See generally Appendix B (EI TSD), Sections 3.1.1.1 and 3.1.1.13.

December 21, 2015 Final 91

 
7.1.1.5 Stagnation Modeling Inventory

The stagnation inventory methodology follows closely to that described in the activity based 

emissions annual inventory described in Chapter 5, except that the inventories for modeling 

purposes were developed specifically for the individual monitor modeling domains and 

emission rates were developed at an hourly scale.

141

7.1.1.6 Other Stagnation Modeling Factors

Emission methodologies for calculating activity based fugitive dust for all land use categories

are described in section 3.1.1 of Appendix B (EI TSD). Any changes in dust generating activities

between 2008 and 2018, other than additional controls resulting from this plan, are described 

in Section 3.2.1 of Appendix B (EI TSD).

7.1.2 High Wind Attainment Modeling Background

7.1.2.1 High Wind Day Condition Description

During high wind conditions, windblown dust emissions from disturbed soil surfaces typically 

dominate PM10 emissions. Windblown dust emission magnitude is directly proportional to wind 

velocity, disturbed surface area, and the soil texture.142 Sources within a narrow band along the 

upwind trajectory tend to contribute significantly to recorded PM10 concentrations, because of 

the tendency of wind trajectories to remain somewhat constant during these periods.143 High 

wind days are comprised of both high wind hours (including windblown and activity emissions)

and low wind hours (containing only activity emissions).

144

7.1.2.2 High Wind Design Day Selection

To identify high wind days, the PM10 exceedance days recorded at each of the six 

nonattainment monitoring sites were screened for high hourly average wind speeds (over 12 

mph) during hours of high PM10 concentrations.145 The analysis of PM10 exceedances on high 

wind days selected four monitors determined to be representative of conditions throughout 

the year, at the sites and dates listed below.146

• Cowtown – April 27, 2008

• Pinal County Housing – January 1, 2008

• Stanfield – November 21, 2008

• Maricopa – October 27, 2008

141 See generally Appendix B (EI TSD), Sections 3.1.1 and 3.2.1. 142 Appendix A (IPP), Section 3.4, p. 52. 143 Appendix A (IPP), Section 3.2, p. 50. 144 See generally Appendix B (EI TSD), Section 2.1. 145 Appendix A (IPP), Section 3.4, p. 52. 146 See Appendix A (IPP), Sections 3.5 through 3.9 for information on the methodology of choosing representative 

dates.

December 21, 2015 Final 92

 
7.1.2.3 High Wind Domain Boundary Selection

7.1.2.3.1 High Wind Hour Domains

A relatively complex approach was used to define domains for high wind days. The domain for 

the high wind hours in the West Pinal nonattainment area followed the methodology that 

Maricopa Association of Governments (MAG) used in the 2012 Five Percent Plan,147 which 

plotted a back trajectory based on the average wind speed and direction recorded for each high 

wind hour.148 

GIS shapefiles developed by PCAQCD and ADEQ provided land use information for the entire 

nonattainment area. However, outside of the 6 km radius supplied by CRPC, no information 

was available for specific crops under cultivation on agricultural lands. This is problematic as 

particulates transport further under high wind conditions, and agriculture is the dominant land 

use within the nonattainment area. Agricultural windblown emissions are strongly affected by 

specific crops under cultivation.149

Transport analysis determined that 80% of the impacts, assuming equivalent source strength, 

would come from sources located within 4 miles of a 12 mile upwind trajectory150. Little insight 

would be gained from characterizing sources beyond the 6 km (3.7 miles). Therefore, ADEQ 

decided to restrict the size of the domain to relevant boundaries within the 6 km CRPC area, 

allowing for the specific domain shape and size definition.

151 Using the approach, a triangular 

domain extends from each monitor along the high wind trajectory hours reflecting the monitor 

specific design day data. The domain is bounded by a 6 km arc.152 Some of the area within the 

domains was actually Gila River Indian Community (GRIC) land.

153 ADEQ could only collect 

limited information from the GRIC, therefore, assumptions were applied for land uses within 

GRIC land.154 

7.1.2.3.2 Low Wind Hour Domains155

Unlike the high wind domains where wind direction and emissions are consistently from a 

single quadrant, wind and emissions impacting the monitor during low wind hours come from 

all directions, similar to stagnation emission impacts. A rectangular domain is defined by the 

maximum hourly wind directions and speeds. The domain is considerably larger than the 6 km 

147 MAG 2012 Five Percent Plan for PM10 for Maricopa County Nonattainment Area, Maricopa Association of 

Governments, May 2012.

148 See Appendix B (EI TSD) for more information on domain methodology development. 149 See generally Appendix B (EI TSD), Section 2. 150 See generally Appendix B (EI TSD), Section 2.1 151 See generally Appendix B (EI TSD), Section 2.1 152 See generally Appendix B (EI TSD), Section 2.1 153 See generally Appendix B (EI TSD), Section 2.1 154 See generally Appendix B (EI TSD), Section 3.1.1.13. 155 Low wind hours are assigned a high wind day domain because high wind days are comprised of both high and 

low wind hours.

December 21, 2015 Final 93

 
radius of crop data provided by CRPC.156 Assumptions were required for land outside of the 

information from CRPC.157 

Low wind hour activity emissions are estimated using the same methods as activity emissions 

on stagnation days. However, low wind hours take place on high wind days (or non-stagnation 

days). Because not every hour of a high wind day will have wind speeds of 12 mph or more, 

calculated activity emissions from low wind hours and high wind hours are added to high wind 

hour windblown dust emission totals. 

7.1.2.4 Model Method Selection - Rollback

The method used to assess high wind hour source apportionment and to provide a basis for 

demonstrating attainment is the weighted rollback method, an approach that was employed in 

MAG’s Five Percent Plan158 and approved by EPA.159 In MAG’s experience, neither AERMOD 

nor photochemical grid models performed well to quantify specific area source contributions to 

monitors during high winds, and in fact were unreliable. MAG developed a more reliable 

rollback approach.160

The weighted rollback approach applies a distance reduction factor to the emissions of each 

source in the modeling domain to help assess the impact of emissions as distance from the 

monitor increases.161 The approach weights the contribution of each upwind source’s emissions 

by the reciprocal of its distance to the monitor and assumes that each source’s fractional 

contribution to the sum of weighted emissions is equal to that source’s fractional contribution 

to the hourly PM10 concentration measured at the downwind monitor (i.e., that the impacts of 

emissions from nearby sources are proportionally greater than the impacts from remote 

sources, assuming equivalent emissions rates among sources).162 

In contrast to Maricopa County, which had not experienced a low wind violation of the PM10 

standard since 2007, Pinal County experienced violations on both stagnation and high wind 

days. A review of high wind day hours revealed that low wind hour concentrations on high wind 

days sometimes exceeded high wind hour concentrations at each of the monitors. Based on this 

finding, decisions were made (1) to model the effect of low wind hour mechanically generated 

emissions and (2) to model both mechanically generated emissions and windblown dust 

emissions during high wind hours.163

156 See generally Appendix B (EI TSD), Section 3.1.2. 157 See generally Appendix B (EI TSD), Sections 3.1.1.1 and 3.1.1.13. 158 Maricopa Association of Governments, MAG 2012 Five Percent Plan for PM-10 for Maricopa County 

Nonattainment Area, Section 6, Attainment Demonstration (May 2012). 

159 See Appendix C (Modeling TSD), Section 3.1. 160 Id. 161 See generally Appendix C (Modeling TSD), Section 3.1, p. 27. 162 See Appendix C (Modeling TSD), Section 1, p. 2. 163 See Appendix C (Modeling TSD), Section 3.1, p. 28.

December 21, 2015 Final 94

 
Therefore, for both high wind hours (>12 mph) and low wind hours (≤12 mph) on high wind 

days, the weighted rollback method was used to assess the relative contribution of each 

upwind source to the hourly monitored PM10 nonattainment area.164

The rollback method as applied assumes (1) emission factor uniformity within “disturbed” and 

“undisturbed” states of surface soil conditions and (2) an inverse relationship between the 

source’s distance from the monitor and the emission impact at that monitor.165 

Because the calculation of windblown emissions can be tricky to follow, below is an example 

high wind calculation for disturbed agricultural land.

Example Windblown Calculation for Disturbed Agricultural Land:

Assume calculation of the hourly windblown emissions from a 50 acre (202,343 m2) cotton field 

located 1.3 miles directly upwind of the Pinal County Housing (PCH) monitor during harvesting 

season for a single hour averaging 22 mph wind speed. This is the fourth consecutive hour of 

high winds (i.e. >12mph) for this wind event and one hour following the maximum measured 

concentration for this wind event at the PCH monitor. The harvesting season is assumed to 

have fully disturbed soil, so use of Equation 1 on page 3-90 of Appendix B is appropriate (Note: 

For those lands determined to be partially disturbed, Equations 1 and 2 on page 3-90 and 3-91 

of Appendix B would be employed and the area utilized in each equation would be the product 

of the area of the parcel and the disturbed fraction and stable fraction of the land of interest, 

respectively.)

EEssss = FFEEEEEEEE EE EEEEEEEEEE × AA × EE DDDD DDDD × VV′

where:

Esj = suspended PM10 in gram/sec for hour j

FEFAdjustment = the emission adjustment factor for diminished particle supply (detailed in 

Appendix B, Exhibit B-VII)

A = the area of each crop’s land parcel, in m2

EFDisturbed,bin = the windblown dust emission factor developed for disturbed soil for a 

given wind speed bin, gram/m2

-sec for hour j (detailed in Appendix B, Exhibit B-V)

V’ = crop specific vegetative cover, presented in Appendix B, Table 3-48

Table 7-1 Values used for Example Windblown Dust Calculation

Variable Value Units Source

164 See Appendix C (Modeling TSD), Section 1, p. 2. 165 See Appendix C (Modeling TSD), Section 1, p. 2.

December 21, 2015 Final 95

 
FEFAdjustment 51 % Appendix BVII, Table BVII-4

A 202,343 m2 Given in assumptions (area of the 

field)

EFDisturbed,bin 4.27E-04 g/m2-s Appendix BV, Table BV-4

V' 0.7 Unit-less Table 3-48

Using the values presented in Table 7-1 and the equation above, we can calculate windblown 

emissions from the cotton field during this single hour of high wind as:

EEssss = 0.51 × 202,343 mm2 × 0.000427 gg

mm2 − ss

× 0.7 = 30.8

gg

ss

× 3600

ss

hrr

÷ 453.6 gg

llll = 244

llll

hrr

The emissions produced within that hour are 245 lbs. This can then be modeled as monitor 

impacts by dividing by the straight-line distance to the monitor (1.3 miles). This results in a 

monitor impact of 188 lb/mile. 

If this impact was assumed to occur on the 2008 Pinal County Housing (PCH) high wind design 

day and only assumed to occur for this one hour, we can normalize this impact to the monitor 

by dividing the individual cotton field’s impact calculated above by the total emission impacts 

on the monitor for that day (25,258 lb/mile; calculated as the sum of the hourly total impacts 

presented in Appendix C (Modeling TSD), Section 3.3, Table 3-1) multiplied by the nonbackground monitor 24-hour average (247.4 μg/m3

)

166. This results in a 24-hr average impact 

of this single cotton field on the monitor of 1.8 μg/m3 for the PCH design day.

7.1.2.5 High Wind Modeling Inventory

With some Pinal specific revisions detailed in the technical supporting documents,167 ADEQ 

closely followed MAG’s 2012 5% PM10 Plan high wind methodology to model for an inventory 

and to identify significant sources within the nonattainment area. ADEQ calculated and 

adjusted high wind emissions factors utilizing the methodology described in Chapter 5. To 

model source impacts on the monitor, design-day specific meteorological information from a 

respective monitor was used in conjunction with design-day calculated emission rates for each 

parcel within the monitor’s modeling domain.

168 Land use categorization determines the

disturbed versus stable land, in turn defining hourly emission rates. Emission methodologies for 

calculating high wind fugitive dust for all land use categories are described in Section 3.1.2 of 

Appendix B (EI TSD).

166 247.4 μg/m3 is calculated as the design day concentration (264.9 μg/m3

) minus the calculated nonanthropogenic background on high risk days (17.5 μg/m3

), See Appendix C (Modeling TSD) Section 3.2 for more 

information.

167 See Appendix B (EI TSD), Section 3.1.2, p.109-110. 168 See Appendix A (IPP), p. 3.

December 21, 2015 Final 96

 
7.1.2.6 Other Factors

Emission methodologies for calculating high wind fugitive dust for all land use categories are 

described in section 3.1.2 of Appendix B (EI TSD). Any changes in high wind emissions between 

2008 and 2018, other than additional controls resulting from this plan, are described in Section 

3.2.2 of Appendix B (EI TSD).

7.1.3 How ADEQ Accounted for Attainment Controls

Generally, attainment was modeled using the rules applicable to crop and animal operations, 

except for dairy operations (these were used for contingency measures). Please find a more 

detailed discussion regarding the Agricultural Rules themselves in Chapter 6 of this document, 

the RACM Document, Appendix F, and the Notice of Exempt Rulemaking, Exhibit G-VI. 

7.1.3.1 Crop Operations 

In order to estimate commercial crop farm emission reductions associated with the 

implementation of this rule, ADEQ required an understanding of which BMPs a commercial 

crop farmer would be most likely to implement for each operation. With the help of the 

Agricultural Best Management Practices Committee (Ag BMP Committee), ADEQ surveyed Pinal 

County crop farmers to determine the likelihood of individual BMP implementation. Farmers 

were surveyed to determine the likely BMP strategies they would implement on individual 

crops on non-high wind and high wind forecasted days. Survey responses were separated by 

crop type. Weighted average control efficiencies for each crop type were calculated and applied 

to the emission rates for those individual crops and activities. The control efficiencies were 

weighted based on survey responses regarding crop acreage and the number of responses 

given for each crop type and associated regulated activity. For more information regarding the 

crop operations survey methodology, please see Section 3.1.1.1 of Appendix D (Attainment 

Demonstration TSD). 

In additions, crop operation activity, distribution, and acreage were assumed constant between 

2008 and 2018. For 2018 controlled calculations, however, high risk control efficiencies were 

applied to design day activity and windblown emissions under the assumption that all design 

days would be forecast as high risk. For windblown emissions, the implementation of the 

AgBMP rule resulted in reduced windblown dust emissions from croplands due to the 

implementation of BMPs that either reduced emissions through ground stabilization or 

increased ground cover.

7.1.3.2 Confined Animal Feeding Operations (CAFOs)

Cattle populations on CAFOs in the nonattainment area in 2018 are expected to be 38% lower 

than in 2008, due mainly to the closing, consolidating, or repurposing of half of the feedlots. 

These closures also reduced windblown dust emissions from the former feedlot sites. For 

windblown modeling purposes, these locations were assumed to transition from the CAFO land 

use to the Cleared Areas land use category. 

December 21, 2015 Final 97
Based on a poll of the CAFO operators who still have active operations in the NA (there are only 

3), ADEQ developed a most likely profile of operational changes that would be in place by 2018 

to facilitate compliance with the new state AgBMP rule. These include a combination of 

watering practices and cleaning schedule changes, as well as traffic controls. For 2018 

controlled calculations, however, high risk control efficiencies were applied to design day 

activity and windblown emissions under the assumption that all design days would be forecast 

as high risk. Based on the estimated number of high risk days, ADEQ estimated that in annual 

terms (not design days), 2018 controls would be 15.5% more effective than 2008 controls in 

reducing activity-driven dust, and 10.1% more effective for windblown dust.

7.1.4 Comparative Concentration Table

Below is a table comparing the past and projected design value concentrations between the 

2008 base year, the projected 2018 base year, and the projected-controlled year 2018. The 

projected-controlled 2018 year only accounts for attainment controls, and no contingency 

controls.

Table 7-2 Comparative Design Day Concentration between Base 2008, Projected 2018, and 

Projected Controlled 2018

Year Design

day

Background 

concentration 

(μg/m3)

Design

value

(μg/m3)

2008

Stagnation

Cowtown

11.5

244.5

Monitor observations

Pinal County 

Housing 178.0

Stanfield 162.0

High-Wind

Cowtown

17.5

168.3

Maricopa 159.4

Pinal County 

Housing 264.9

Stanfield 178.6

2018

Stagnation

Cowtown

11.5

188.4

Modeled projections

Pinal County 

Housing 179.6

Stanfield 197.7

High-Wind

Cowtown

17.5

163.7

Maricopa 140.0

Pinal County 

Housing 262.7

Stanfield 186.0

-

Att

ain

gn

ati

Cowtown 11.5 152.5 j

pro

ed 

December 21, 2015 Final 98
Pinal County 

Housing 154.9

Stanfield 154.7

High-Wind

Cowtown

17.5

120.8

Maricopa 124.3

Pinal County 

Housing 135.3

Stanfield 112.2

7.1.5 Annual Inventory Attainment Reductions

Below is a table reiterating the amount of reductions achieved by the agricultural rule alone 

(not including provisions applicable to dairy operations or canal access roads).

Table 7-3 Annual Inventory Reductions from the Attainment Targeting Sections of the Ag BMP 

Rules (TPY)

Land Use/Source Category

Unpaved 

apron 

roads

Unpaved 

canal 

O&M 

roads

Harvesting 

and Tilling CAFOs

Windblow

n Dust

Unpaved Roads 705.2 144.7

CAFOs 29.9

Agriculture 12388.1

Subtotal 705.2 144.7 12388.1 29.9

Activity-based 

emissions

Ag Fields - Harvesting 105.8

Ag Fields - Tilling 882.3

CAFOs 251.4

Unpaved Roads 7341.3 577.6

Subtotal 7341.3 577.6 988.1 251.4

Total 8045.5 722.3 13376.2 281.3

Grand Total 22426.3

7.2 Reasonable Further Progress 

Under section 189(c)(1), this nonattainment plan must demonstrate Reasonable Further 

Progress (RFP), which “means such annual incremental reductions in emissions of the relevant 

air pollutant as are required by this part or may reasonably be required by the Administrator for 

December 21, 2015 Final 99
the purpose of ensuring attainment of the applicable national ambient air quality standard by 

the applicable date.”169

EPA has stated in guidance, “where the nonattainment problem is attributed to area type 

sources (e.g., fugitive dust, residential wood combustion, etc.), RFP should be met by showing 

annual incremental emission reductions generally sufficient to maintain linear progress towards 

attainment. Total PM-10 emissions should not remain constant or increase from 1 year to the 

next in such an area."170 The annual incremental emission reductions to be achieved should be

reasonable in light of the statutory objective to ensure timely attainment of the PM10

NAAQS.171 

The West Pinal nonattainment area is projected to reduce emissions to meet attainment within 

a three year period, with annual inventory reductions totaling 22,426.3 tons over the three 

years. With a three-year horizon from the end of 2015 to modeled attainment at the end of 

2018, a linear implementation schedule would require a glide path showing annual reductions 

7475.4 tons per year. 

The actual implementation plan causes an acute reduction in the first year, from the end of 

2015 to the end of 2016, followed by slow and steady reductions until the end of 2018. The 

actual implementation and emissions reductions path is projected to be quite steep in the first 

year because the measures credited toward attainment, the agricultural rules, are more fitted 

for upfront reduction credit. In the relatively short amount of time within which the West Pinal 

nonattainment area must reduce PM10 emissions to meet the attainment date, the chosen glide 

path in Figure 7-1 below is the most reasonable solution and representation of reasonable 

further progress to meet attainment. 

169 C.A.A. § 171(1) (2012). 170 Proposed Approval of Maricopa County PM10 Nonattainment Area Five Percent Plan, 79 FR 7118 at 7123 (Feb. 

6, 2014).

171 Addendum to the General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990, 

59 FR 41998, 42015 (Aug. 16, 1994).

December 21, 2015 Final 100

 
Figure 7-1 Reasonable Further Progress from Dec. '15 through Dec. '18

Figure 7-2: Reasonable Further Progress from Dec. '15 through Dec. '18

Reasonable Further Progress qualitative milestones must be achieved every three years. In the 

case that the agricultural rules developed for attainment under this plan do not alone allow for 

the achievement of qualitative milestones every three years, contingency measures will already 

be in place to assure attainment. 

If an area fails to make reasonable further progress, CAA Section 172(c)(9) requires the 

implementation of contingency measures. EPA recommends that contingency measures for 

PM10 nonattainment areas provide emission reductions equivalent to one year's average 

increment of RFP.

172 EPA has further interpreted section 172(c)(9) to allow states to implement 

contingency measures before they are triggered by a failure of RFP or attainment as long as 

172 Addendum to the General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990, 

59 FR 41998, 42014 (Aug. 16, 1994).

105,000

110,000

115,000

120,000

125,000

130,000

135,000

140,000

2015 2016 2017 2018

Annual NA-Wide Emissions (TPY)

Glide Path Actual Implementation Schedule

December 21, 2015 Final 101

 
those measures are intended to achieve reductions over and beyond those relied on in the 

attainment and RFP demonstrations.173

ADEQ has provided for additional emissions controls and consequent reductions that will 

ensure continued progress toward attainment and RFP past the attainment date until the West 

Pinal Area is redesignated. These measures include the agricultural dairy controls, the Pinal 

County construction controls, trackout controls, and most of all, the Pinal County General 

Fugitive Dust Rule. The reductions from all of these rules and provisions is projected to total 

7,474.8 by 2018, as shown in Table 7-4 below.174

Table 7-4 Summary of Contingency Measure Reductions

Rule Controlled Dust Sources Implementation 

date

Reductions in

2018 (TPY)

Arizona Administrative 

Code, R18-2-611.03

Commercial dairy 

operations January 1, 2016 101.2

PCAQCD Code of 

Regulations, §4-3-160, 

-170, -180, and -190

Permitted construction

projects January 1, 2016 4,679.4175

PCAQCD Code of 

Regulations, §4-1-010, 

-015, -020, -030, -040, 

-045, -050, and -060

Several prescribed area 

sources of fugitive dust, 

including vacant lots and 

other open areas, roads, 

and other traffic areas.

Effective January 

1, 2016, with some 

controls being 

implemented 

progressively

2,962.3

Total 7,742.9

In addition, PM10 nonattainment SIPs are required by section 189(c) to contain quantitative 

milestones to be achieved every three years and which are consistent with RFP for the area. 

These quantitative milestones should consist of elements which allow progress to be quantified 

or measured.176 The quantitative milestones are "to be achieved until the area is redesignated 

attainment."177

According to current EPA policy, the three year quantitative milestone report requirement runs 

from the nonattainment SIP submittal due date,178 which, in this case, was 18 months from the 

173 See Proposed Approval of Maricopa County Serious Nonattainment Area Plan, 75 FR 54806, at 54815 (Sept. 9, 

2010). See generally, LEAN v. EPA, 382 F.3d 575 (5th Cir. 2004). See also General Preamble for the Implementation 

of Title I of the Clean Air Act Amendments of 1990, 57 Fed. Reg. 13,498, at 13512. 174 For more information regarding the details of contingency measure calculations to meet one year’s worth of 

RFP, please see Appendix D, Section D5.2.

175 Up to 5 TPY of reductions attributed to the construction rule may actually be attributable to the general fugitive 

dust rule instead, but were consolidated in the construction rule subtotal as an expediency. See Appendix D 

Sections D5.2.2.1 and D5.2.3.4 for details.

176 Addendum to the General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990, 

59 FR 41998, 42016 (Aug. 16, 1994). 177 C.A.A. § 189(c) (2012). 178 Fine Particulate Matter NAAQS SIP Requirements, 80 FR 15340, 15390 (proposed Mar. 23, 2015).

December 21, 2015 Final 102

 
effective redesignation date, July 12, 2012. To align with the policy, the ADEQ intends to submit 

West Pinal PM10 milestone report in the beginning of 2017. ADEQ’s report will adequately 

quantify and track progress with its RFP goals. ADEQ anticipates submitting a report that first, 

demonstrates how emissions reductions achieved by the beginning of 2017 compare to those 

scheduled, second, analyzes the correlation between the plan and monitoring data, and third, 

projects whether the area will still meet its scheduled attainment date, also taking into account 

the already implemented contingency measures. 

Generally, ADEQ intends to analyze chosen agricultural BMPs and reduction progress using the 

agricultural rule’s surveys. In the absence of adequate or representative data, ADEQ expects to 

use apropos compliance data. For example, ADEQ anticipates reporting on the number of 

producers in compliance at the time of inspection, according to the chosen attainment 

measures, A.A.C. R18-2-610, -610.03, -611, -611.03(A), (C), & (E)-(O), -612, and -612.01(A)(1) & 

(B)-(J). In the event it is more accurate than survey data, ADEQ also anticipates using inspection 

data and/or data from the General Permit Record Forms as reviewed during inspections in 

order to determine which PM10 reducing BMPs inspected agricultural operations use. From this 

data, ADEQ may estimate reductions and compare these figures to the projected reductions in 

this plan.

December 21, 2015 Final 103