MAG 2012 FIVE PERCENT PLAN FOR PM-10 FOR THE

MARICOPA COUNTY NONATTAINMENT AREA

MAY 2012
MAG 2012 FIVE PERCENT PLAN FOR PM-10 FOR THE 

MARICOPA COUNTY NONATTAINMENT AREA

Prepared by:

May 2012

Technical Assistance Provided By:

Arizona Department of Environmental Quality

Arizona Department of Transportation

Maricopa County Air Quality Department

U.S. Environmental Protection Agency
MAG 2012 FIVE PERCENT PLAN FOR PM-10 FOR THE

 MARICOPA COUNTY NONATTAINMENT AREA

TABLE OF CONTENTS

CHAPTER PAGE

EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ES-1

ONE INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

HISTORICAL BACKGROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

OUTLINE OF THE MAG 2012 FIVE PERCENT

PLAN FOR PM-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

TWO DESCRIPTION OF THE NONATTAINMENT AREA . . . . . . . . . . . . 2-1

NONATTAINMENT AREA BOUNDARIES . . . . . . . . . . . . . . . . . . . . 2-1

GEOGRAPHY AND CLIMATIC CONDITIONS . . . . . . . . . . . . . . . . . 2-3

THREE ASSESSMENT OF AIR QUALITY CONDITIONS . . . . . . . . . . . . . . 3-1

FORMATION OF PM-10 PARTICULATE POLLUTION . . . . . . . . . . 3-1

PM-10 EMISSIONS INVENTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

AIR QUALITY MONITORING DATA AND TREND ANALYSIS . . . . . 3-4

FOUR THE ADOPTED PLAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

MARICOPA COUNTY RESOLUTION TO EVALUATE

MEASURES IN THE MAG 2012 FIVE PERCENT PLAN 

FOR PM-10 FOR THE MARICOPA COUNTY 

NONATTAINMENT AREA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

ARIZONA DEPARTMENT OF ENVIRONMENTAL QUALITY 

DUST ACTION GENERAL PERMIT . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

i
TABLE OF CONTENTS (Continued)

CHAPTER PAGE

ARIZONA DEPARTMENT OF ENVIRONMENTAL QUALITY

COMMITMENT TO REVISE THE MAG 2012 FIVE PERCENT

PLAN FOR PM-10 FOR THE MARICOPA COUNTY 

NONATTAINMENT AREA IF NECESSARY FOR THE 

EMERGING AND VOLUNTARY MEASURE . . . . . . . . . . . . . . . . . . . 4-6

CONTINGENCY REQUIREMENT . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7

ASSURANCES THAT THE STATE HAS THE AUTHORITY

TO IMPLEMENT THE MEASURES IN THE PLAN . . . . . . . . . . . . . . 4-7

TRACKING IMPLEMENTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8

FIVE DEMONSTRATION OF ANNUAL FIVE PERCENT 

REDUCTIONS IN PM-10 EMISSIONS . . . . . . . . . . . . . . . . . . . . . . . 5-1

MEASURES QUANTIFIED TO MEET THE FIVE

PERCENT REDUCTION REQUIREMENT . . . . . . . . . . . . . . . . . . . . 5-1

DEMONSTRATION FOR THE FIVE PERCENT 

REDUCTION REQUIREMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4

SIX ATTAINMENT DEMONSTRATION . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

SALT RIVER AREA MODELING . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

PM-10 NONATTAINMENT AREA MODELING . . . . . . . . . . . . . . . . 6-15

REASONABLE FURTHER PROGRESS . . . . . . . . . . . . . . . . . . . . . 6-34

CONTINGENCY REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . 6-35

ONROAD MOBILE SOURCE EMISSIONS BUDGET

FOR CONFORMITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-42

EXPEDITIOUS ATTAINMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-43

ATTAINMENT DATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-44

REQUEST FOR EXTENSION OF THE ATTAINMENT

DATE FROM JUNE 6, 2012 TO DECEMBER 31, 2012 . . . . . . . . . 6-45

ii
MAG 2012 FIVE PERCENT PLAN FOR PM-10 FOR THE

 MARICOPA COUNTY NONATTAINMENT AREA

LIST OF TABLES

TABLE PAGE

Table ES-1 2007-2012 Base Case PM-10 Emissions in the

PM-10 Nonattainment Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ES-6

Table ES-2 Arizona Statutes, Maricopa County Rules, Maricopa

County Ordinance, and Appendices to be Approved 

into the MAG 2012 Five Percent Plan for PM-10 for the 

Maricopa County Nonattainment Area . . . . . . . . . . . . . . . . . . . . . ES-8

Table ES-3 2008-2012 PM-10 Emissions with Increased Rule

Effectiveness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ES-11

Table ES-4 PM-10 Emission Reductions and Five Percent

Reduction Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ES-13

Table ES-5 Miles of Roads/Alleys/Shoulders in PM-10 Reduction

Projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ES-13

Table ES-6 2008-2012 PM-10 Reductions to Meet Contingency

Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ES-14

Table ES-7 2008-2012 PM-10 Emissions with Five Percent Plan

Measures and Contingency Projects . . . . . . . . . . . . . . . . . . . . . . ES-15

Table 3-1 Annual Emissions for the PM-10 Nonattainment Area

from all Source Categories Included in the 2008 Periodic 

Emissions Inventory for PM-10 (English Tons/Year) . . . . . . . . . . . . . 3-3

Table 3-2 PM-10 Monitoring Stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6

Table 3-3 Exceedances of the 24-Hour PM-10 Standard,

2005 to 2007 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10

Table 3-4 Exceedances of the 24-Hour PM-10 Standard,

2008 to 2010 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11

iii
LIST OF TABLES (Continued)

TABLE PAGE

Table 4-1 Arizona Statutes, Maricopa County Rules, Maricopa

County Ordinance, and Appendices to be Approved 

into the MAG 2012 Five Percent Plan for PM-10 for the 

Maricopa County Nonattainment Area . . . . . . . . . . . . . . . . . . . . . . . 4-2

Table 5-1 Impact of Increased Rule Effectiveness on 2008-2012

PM-10 Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3

Table 5-2 2007-2012 Base Case PM-10 Emissions in the PM-10

Nonattainment Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5

Table 5-3 2008-2012 PM-10 Emissions with Increased Rule

Effectiveness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

Table 5-4 PM-10 Emission Reductions and Five Percent

Reduction Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8

Table 6-1 Maricopa County and PM-10 Nonattainment Area

24-Hour Average PM-10 Standard Exceedance Dates,

Measured Concentrations and Associated Meteorological

Conditions in 2007 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3

Table 6-2 Base Case 2007 and Controlled 2012 High Wind PM-10

Emissions Inventories for May 4, 2007 Design Day at the

West 43rd Avenue Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-11

Table 6-3 Annual Base Case 2007 and Controlled 2012 Low Wind

PM-10 Emissions Inventories for the Salt River Area

Low Wind Domain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-13

Table 6-4 2012 Attainment Demonstration High Wind Design Day

(May 4, 2007) at the West 43rd Avenue Monitor . . . . . . . . . . . . . . . 6-14

Table 6-5 24-Hour Average PM-10 Concentrations on the High

Wind Design Day (June 6, 2007) . . . . . . . . . . . . . . . . . . . . . . . . . . 6-16

Table 6-6 Base Case 2007 and Controlled 2012 High Wind PM-10

Emissions Inventories for June 6, 2007 Design Day at the

Central Phoenix Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-19

iv
LIST OF TABLES (Continued)

TABLE PAGE

Table 6-7 Base Case 2007 and Controlled 2012 High Wind PM-10

Emissions Inventories for June 6, 2007 Design Day at the

Durango Complex Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-20

Table 6-8 Base Case 2007 and Controlled 2012 High Wind PM-10

Emissions Inventories for June 6, 2007 Design Day at the

Greenwood Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-21

Table 6-9 Base Case 2007 and Controlled 2012 High Wind PM-10

Emissions Inventories for June 6, 2007 Design Day at the

Higley Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-22

Table 6-10 Base Case 2007 and Controlled 2012 High Wind PM-10

Emissions Inventories for June 6, 2007 Design Day at the

West Phoenix Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-23

Table 6-11 Base Case 2007 and Controlled 2012 High Wind PM-10

Emissions Inventories for June 6, 2007 Design Day at the

West 43rd Avenue Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-24

Table 6-12 Annual Base Case 2007 and Controlled 2012 Low Wind

PM-10 Emissions Inventories for the Central City Low

Wind Domain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-25

Table 6-13 Annual Base Case 2007 and Controlled 2012 Low Wind

PM-10 Emissions Inventories for the Higley Low Wind

Domain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-26

Table 6-14 2012 Attainment Demonstration High Wind Design Day

(June 6, 2007) at the Central Phoenix Monitor . . . . . . . . . . . . . . . . 6-27

Table 6-15 2012 Attainment Demonstration High Wind Design Day

(June 6, 2007) at the Durango Complex Monitor . . . . . . . . . . . . . . 6-28

Table 6-16 2012 Attainment Demonstration High Wind Design Day

(June 6, 2007) at the Greenwood Monitor . . . . . . . . . . . . . . . . . . . . 6-29

Table 6-17 2012 Attainment Demonstration High Wind Design Day

(June 6, 2007) at the Higley Monitor . . . . . . . . . . . . . . . . . . . . . . . . 6-30

Table 6-18 2012 Attainment Demonstration High Wind Design Day

(June 6, 2007) at the State Super Site Monitor . . . . . . . . . . . . . . . . 6-31

v
LIST OF TABLES (Continued)

TABLE PAGE

Table 6-19 2012 Attainment Demonstration High Wind Design Day

(June 6, 2007) at the West Phoenix Monitor . . . . . . . . . . . . . . . . . . 6-32

Table 6-20 2012 Attainment Demonstration High Wind Design Day

(June 6, 2007) at the West 43rd Avenue Monitor . . . . . . . . . . . . . . . 6-33

Table 6-21 Miles of Roads/Alleys/Shoulders in PM-10 Reduction

Projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-38

Table 6-22 2008-2012 PM-10 Reductions to Meet Contingency

Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-39

Table 6-23 2008-2012 PM-10 Emissions with Five Percent Plan

Measures and Contingency Projects . . . . . . . . . . . . . . . . . . . . . . . . 6-40

vi
MAG 2012 FIVE PERCENT PLAN FOR PM-10 FOR THE

 MARICOPA COUNTY NONATTAINMENT AREA

LIST OF FIGURES

FIGURE PAGE

Figure ES-1 Number of 24-Hour PM-10 Exceedance Days . . . . . . . . . . . . . . . ES-3

Figure ES-2 Exceedances of the 24-Hour PM-10 Standard at Monitors

in Maricopa County . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ES-4

Figure ES-3 2008 PM-10 Emissions Inventory . . . . . . . . . . . . . . . . . . . . . . . . . ES-5

Figure ES-4 2012 PM-10 Emissions Inventory with Five Percent

Plan Measures and Contingency Projects . . . . . . . . . . . . . . . . . . ES-16

Figure 2-1 PM-10 Nonattainment Area and Municipal Planning

Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Figure 3-1 2008 PM-10 Emissions Inventory . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

Figure 3-2 PM-10 Nonattainment Area and PM-10 Monitoring Sites . . . . . . . . . 3-7

Figure 3-3 Number of 24-Hour PM-10 Exceedance Days . . . . . . . . . . . . . . . . . 3-9

Figure 6-1 Summary of the Monitoring Conditions at West 43rd

Avenue on the High Wind Design Day (May 4, 2007) . . . . . . . . . . . . 6-5

Figure 6-2 Summary of the Monitoring Conditions at West 43rd

Avenue on the High Wind Design Day (June 6, 2007) . . . . . . . . . . . 6-6

Figure 6-3 Summary of the Monitoring Conditions at Higley on

the High Wind Design Day (June 6, 2007) . . . . . . . . . . . . . . . . . . . . 6-7

Figure 6-4 Salt River Area Low Wind Domains and May 4, 2007 

Hourly High Wind Back Trajectories and Associated 

Domains as Originating from West 43rd Avenue Monitor . . . . . . . . . . 6-8

Figure 6-5 PM-10 Nonattainment Area Low Wind Domains and

June 6, 2007 Hourly High Wind Back Trajectories

and Associated Domains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-17

vii
LIST OF FIGURES (Continued)

FIGURE PAGE

Figure 6-6 Demonstration of Reasonable Further Progress . . . . . . . . . . . . . . . 6-36

Figure 6-7 2012 PM-10 Emissions Inventory with Five Percent

Plan Measures and Contingency Projects . . . . . . . . . . . . . . . . . . . . 6-41

viii
MAG 2012 FIVE PERCENT PLAN FOR PM-10 FOR THE

 MARICOPA COUNTY NONATTAINMENT AREA

APPENDICES

APPENDIX A

Exhibit 1: 2008 PM-10 Periodic Emissions Inventory for the Maricopa County,

Arizona, Nonattainment Area. Maricopa County Air Quality Department. 

Revised June 2011.

APPENDIX B

Exhibit 1: Technical Document in Support of the MAG 2012 Five Percent Plan for

PM-10 for the Maricopa County Nonattainment Area. Maricopa

Association of Governments.

Exhibit 2: Calculation of Benefits from PM-10 Certified Street Sweepers Purchased

with CMAQ Funds in 2001-2009.

APPENDIX C

Exhibit 1: Arizona Revised Statutes Listed in Table 4-1.

Exhibit 2: Maricopa County Resolution to Evaluate Measures in the MAG 2012 Five

Percent Plan for PM-10 for the Maricopa County Nonattainment Area.

Exhibit 3: Arizona Department of Environmental Quality Dust Action General Permit.

Exhibit 4: Arizona Department of Environmental Quality Commitment to Revise the

MAG 2012 Five Percent Plan for PM-10 for the Maricopa County

Nonattainment Area if Necessary for the Emerging and Voluntary

Measure.

APPENDIX D

Exhibit 1: Agricultural Best Management Practices Program.

APPENDIX E

Exhibit 1: Public Hearing Process Documentation.

Exhibit 2: Certification of Adoption.

ix
MAG 2012 FIVE PERCENT PLAN FOR PM-10 FOR THE

MARICOPA COUNTY NONATTAINMENT AREA

EXECUTIVE SUMMARY
MAG 2012 FIVE PERCENT PLAN FOR PM-10

EXECUTIVE SUMMARY

Within the Maricopa County nonattainment area, the National Ambient Air Quality Standard

has not yet been attained for PM-10 particulate pollution. The area is classified as a

Serious Area under the Clean Air Act. The Maricopa Association of Governments (MAG)

was designated by the Governor of Arizona in 1978 and recertified by the Arizona

Legislature in 1992 to serve as the Regional Air Quality Planning Agency to develop plans

to address air pollution problems. The plans are prepared through a coordinated effort with

the Arizona Department of Environmental Quality (ADEQ), Arizona Department of

Transportation, and Maricopa County Air Quality Department (MCAQD).

To meet the requirements of Section 189(d) of the Clean Air Act, the MAG 2007 Five

Percent Plan for PM-10 was submitted to the Environmental Protection Agency (EPA) by

the federal deadline of December 31, 2007. Collectively, the Five Percent Plan included

fifty-three control measures from the State, Maricopa County, and local governments. The

plan demonstrated that the measures would reduce PM-10 emissions by at least five

percent per year and demonstrated attainment of the PM-10 standard in 2010. The region

needed three years of clean data at the monitors in 2008, 2009 and 2010 in order for the

region to be in attainment of the PM-10 standard in 2010. There have been no violations

of the standard during stagnant conditions since the plan was submitted in 2007.

On September 9, 2010, EPA had published a notice of proposed partial approval and

disapproval of the plan in the Federal Register. There were two major reasons for the

proposed disapproval: the EPA nonconcurrence with four high wind exceptional events at

the West 43rd Avenue monitor in 2008 resulted in a violation, which negated the attainment

demonstration, and that the 2005 baseline emissions inventory was inaccurate since it

overestimated construction and other emissions.

On January 25, 2011, the Arizona Department of Environmental Quality voluntarily

withdrew the MAG 2007 Five Percent Plan for PM-10 to address technical approvability

issues and include new information, such as the new EPA equation for paved road dust

emissions. While the plan was withdrawn, the measures continue to be implemented to

reduce PM-10.

Consequently, the MAG 2012 Five Percent Plan for PM-10 has been prepared to meet the

requirements in Section 189(d) of the Clean Air Act and improve air quality in the Maricopa

County nonattainment area. The plan is required to reduce PM-10 emissions by at least

five percent per year until the standard is attained as measured by the monitors. The

Clean Air Act specifies that the plan must be based upon the most recent emissions

inventory for the area and also include a modeling demonstration of attainment. The 2012

Five Percent Plan is designed to be a replacement for the 2007 plan that was withdrawn.

The formation of PM-10 particulate pollution is dependent upon several factors. Among

ES - 1
these factors are stagnant air masses, severe temperature inversions in the winter, high

winds from thunderstorms and frontal systems, and fine, silty soils characteristic of desert

locations. In the nonattainment area, high PM-10 concentrations generally occur in

September through March, on days with stagnant or near-stagnant conditions. High PM-10

concentrations can also occur during thunderstorm outflows and frontal systems which

create high winds that entrain soil particles from bare surfaces. 

The trend in PM-10 levels for the Maricopa County nonattainment area is presented in

Figure ES-1. The 24-hour PM-10 standard is 150 micrograms per cubic meter. In 2008,

there were 11 exceedance days of the 24-hour standard. Most of these exceedances were

exceptional events. However, EPA did not concur with four high wind exceptional event

days at the West 43rd Avenue monitor in 2008, resulting in a violation of the PM-10

standard. All of the seven exceedance days in 2009 have been flagged as exceptional

events and EPA concurrence is pending. In 2010, only one exceedance day of the PM-10

standard occurred, which did not constitute a violation of the standard. Figure ES-2

indicates the monitors where exceedances have occurred.

It is important to note that beginning in 2004, the Arizona Department of Environmental

Quality began flagging exceptional events. These are uncontrollable natural events (e.g.,

high winds, wildfires) or human-caused events that are not expected to recur at a given

location (e.g., fireworks). The data and a demonstration of the exceptional event are

submitted to EPA for concurrence.

Based upon the Maricopa County Air Quality Department 2008 Periodic Emissions

Inventory (PEI) for PM-10 for the Maricopa County Nonattainment Area, the primary

sources of PM-10 are: Unpaved Road Fugitive Dust - 24 percent; Construction Activities

(residential, commercial, road, and other earthmoving) - 17 percent; Paved Road Fugitive

Dust - 14 percent; Windblown Dust - 10 percent; and Onroad Mobile Vehicle Exhaust, Tire

Wear and Brake Wear - 7 percent. The remaining categories in the inventory individually

contribute 6 percent or less to the total annual emissions. The sources are depicted in

Figure ES-3.

The 2007 and 2009-2012 base case emissions were derived from the 2008 PEI emissions,

using annual population and employment growth factors published in August 2011 by

Marshall Vest of the Economic and Business Research Center at the University of Arizona.

These projections are based on the 2010 U.S. Census and the latest economic forecasts

for the Phoenix-Mesa metropolitan area. Since the economic outlook for Arizona remains

extremely unstable, the actual population and employment levels in 2011 and 2012 may

differ somewhat from the projections. However, the University of Arizona growth factors

represent the most reliable data currently available.

The annual five percent reduction target was calculated by multiplying the total 2007 PM-10

emissions in Table ES-1 (59,218 tons) by five percent, which results in 2,961 tons. To

meet the 189(d) requirement, the 2008 emissions must be at least 2,961 tons less than 

ES - 2
Figure ES-1

Number of 24-Hour PM-10 Exceedance Days

Notes: -The Arizona Department of Environmental Quality began flagging exceptional events in 2004. 

-The chart includes exceedance days at the Buckeye monitor, which is located outside the PM-10 nonattainment ar-On July 19, 2007, the exceedance at the Buckeye monitor was not associated with the exceptional event that also 

Sources: 1988 - 1997 - Revised MAG 1999 Serious Area Particulate Plan for PM-10 for the Maricopa County Nonattainme

1998 - 2010 - EPA Air Quality System.

27

19

3 4 2

6 7 8

4

13 11

18

10

0

2

0 0

3

0

ES - 3
Figure ES-2

Exceedances of the 24-Hour PM-10 Standard at Monitors in Maricopa County

Notes:1. Exceedances are based on data from the EPA Air Quality System (AQS).2. All exceedances in 2008 except for one at the Durango Complex monitor have been flagged as exceptional events. 

four exceptional events at the West 43rd Avenue monitor and has not taken action on the remaining events.

3. All exceedances in 2009 have been flagged as exceptional events. EPA concurrence is pending.4. The one exceedance in 2010 was not flagged as an exceptional event.5. The chart includes exceedances from the Buckeye monitor, which is outside the PM-10 nonattainment area.

012345678

W. 

43rd AveBuc keyeDurango S. Phoenix Coyote Lakes Higley W. ChandlerBe thune W. PhoenixGlendale Dysart 

Number of Exceedances

2008 2009 2010

ES - 4
Figure ES-3

ES - 5
Table ES-1

2007-2012 Base Case PM-10 Emissions in the PM-10 Nonattainment Area

Source Category

2007 2008 2009 2010 2011 2012

(tons/year)

POINT 159 150 133 127 128 135

AREA

Fuel combustion 1,276 1,301 1,307 1,311 1,316 1,328

Commercial cooking 974 993 998 1,001 1,005 1,014

Construction (includes windblown dust) 16,672 13,811 9,692 8,359 8,102 8,223

Tilling, harvesting and cotton ginning 936 893 893 893 893 893

Travel on unpaved farm roads 769 731 731 731 731 731

Livestock 261 261 261 261 261 261

Travel on unpaved parking lots 2,376 2,422 2,434 2,441 2,451 2,473

Offroad recreational vehicles 2,139 2,180 2,191 2,198 2,206 2,226

Leaf blowers 878 895 899 902 906 914

Windblown agriculture 448 448 448 448 448 448

Other windblown sources 5,430 5,430 5,430 5,430 5,430 5,430

Fires 497 497 497 497 497 497

Mining/quarrying (includes windblown

dust) 752 721 661 641 643 667

Travel on industrial paved/unpaved roads 771 728 645 618 621 654

Other industrial sources 1,033 976 865 828 832 877

NONROAD

Aircraft 194 184 152 142 143 146

Airport ground support equipment 29 27 23 21 20 20

Locomotives 34 34 34 34 34 34

Other nonroad equipment 1,710 1,683 1,661 1,641 1,595 1,513

ONROAD

Exhaust 2,943 2,836 2,647 2,371 1,843 1,407

Tire wear 246 256 257 257 258 261

Brake wear 728 758 767 771 773 787

Paved roads 7,749 8,155 8,214 8,289 8,323 8,422

Unpaved roads and alleys 10,218 10,312 10,284 10,284 10,284 10,312

Totals 59,218 56,681 52,123 50,497 49,743 49,673

ES - 6
the 2007 base case emissions. Each year after 2008 imposes yet another 2,961 ton

reduction requirement. Thus, the cumulative reduction requirements (relative to 2007 base

case emissions) are at least 5,922 tons in 2009, 8,883 tons in 2010, 11,844 tons in 2011,

and 14,805 tons in 2012. 

The new MAG 2012 Five Percent Plan for PM-10 contains a wide variety of existing control

measures and projects that have been implemented to reduce PM-10 and a new measure

designed to reduce PM-10 during high risk conditions, including high winds. While the

2007 Five Percent Plan was withdrawn, a wide range of control measures in that plan

continue to be implemented to reduce PM-10 and are being resubmitted. Table ES-2

includes the Arizona Statutes, Maricopa County Rules, a Maricopa County Ordinance, and

Appendices for the resubmitted measures and a new high risk measure to be approved into

the MAG 2012 Five Percent Plan for PM-10 for the Maricopa County Nonattainment Area. 

The 2012 Five Percent Plan also includes contingency measures that were implemented

early such as PM-10 certified street sweeping on freeways and arterials, as well as the

projects completed in 2008-2011 that paved and stabilized unpaved roads, alleys and

shoulders; reduced speed limits; and overlaid highways with rubberized asphalt.

As described in Table ES-2, the Arizona Statutes, Maricopa County Rules, and Maricopa

County Ordinance include requirements to reduce PM-10 emissions from a broad range

of sources. The requirements apply to unpaved roads and shoulders, leaf blowers,

unpaved parking lots, vacant lots, sweeping streets with certified sweepers, off-road vehicle

use, open and recreational burning, residential woodburning, covered vehicle loads, dust

generating operations, nonmetallic mineral processing, and other unpermitted sources.

To meet the annual five percent reduction requirement in Section 189(d) of the Clean Air

Act, the MAG 2012 Five Percent Plan takes credit for increases in rule effectiveness for

Maricopa County Rules 310 (Fugitive Dust from Dust-Generating Operations), 310.01

(Fugitive Dust from Non-Traditional Sources of Fugitive Dust) and 316 (Nonmetallic Mineral

Processing). The increases in rule effectiveness are attributable to strengthened

enforcement and increased compliance with these rules. EPA has approved Rules 310

and 310.01 in 2010 and Rule 316 in 2009, as part of the State Implementation Plan. 

Compliance with these rules has increased every year since 2007. 

These Maricopa County rules also reduce emissions from a wide variety of sources and

apply to the Maricopa County area. Maricopa County Rule 310 (Fugitive Dust from DustGenerating Operations) regulates fugitive dust emissions from sources and activities such

as: land clearing, earthmoving, weed abatement, excavating, construction, demolition, bulk

material handling, storage and transporting operations, outdoor equipment, motorized

machinery, staging areas, parking areas, material storage areas, haul roads, disturbed

surface areas, initial landscapes and trackout onto paved surfaces from these sources.

Maricopa County Rule 310.01 (Fugitive Dust from Non-Traditional Sources of Fugitive

Dust) regulates fugitive dust emissions from sources and activities such as: vehicle use in 

ES - 7
Table ES-2

Arizona Statutes, Maricopa County Rules, Maricopa County Ordinance, 

and Appendices to be Approved into the MAG 2012 Five Percent Plan for PM-10

for the Maricopa County Nonattainment Area

Arizona Revised

Statutes (A.R.S.) Description 

Effective

Dates

A.R.S. § 9-500.04.

Only A.3., A.5.,

A.6., A.7., A.8., A.9.

and H. 

Air quality control; definitions [city and town requirements

in Area A regarding targeting unpaved roads and

shoulders; leaf blower restrictions; restrictions related to

parking, maneuvering, ingress and egress areas and

vacant lots; requirement for certified street sweepers]

9/19/07

A.R.S. § 9-500.27. Off-road vehicle ordinance; applicability; violation;

classification

9/19/07

A.R.S. § 11-871.

Only A., B. and D.4.

Emissions control; no burn; exemptions; penalty [no burn

restriction for any HPA day, increased civil penalty]

9/19/07

A.R.S. § 11-877. Air quality control measures [county leaf blower

restrictions]

9/19/07

A.R.S. § 28-1098.

Only A. and C.1.

Vehicle loads; restrictions; civil penalties [for safety or air

pollution prevention purpose]

9/19/07

A.R.S. § 49-424.

Only 11.

Duties of department [develop and disseminate air quality

dust forecasts for the Maricopa County PM-10

nonattainment area]

7/20/11

A.R.S. § 49-457.01. Leaf blower use restrictions and training; leaf blower

equipment sellers; informational material; outreach;

applicability

9/19/07

A.R.S. § 49-457.03. Off-road vehicles; pollution advisory days; applicability;

penalties

9/19/07

A.R.S. § 49-457.04. Off-highway vehicle and all-terrain vehicle dealers;

informational material; outreach; applicability

9/19/07

A.R.S. § 49-457.05.

Only A., B., C., D.

and I.

Dust action general permit; best management practices;

applicability; definitions

7/20/11

A.R.S. § 49-474.01.

Only A.4., A.5.,

A.6., A.7., A.8.,

A.11., B. and H.

Additional board duties in vehicle emissions control areas;

definitions [county requirements for stabilization of

targeted unpaved roads, alleys and shoulders; restrictions

related to parking, maneuvering, ingress and egress areas

and vacant lots; requirement for certified street sweepers] 

9/19/07

A.R.S. § 49-474.05. Dust control; training; site coordinators 9/19/07

A.R.S. § 49-474.06. Dust control; subcontractor registration; fee 9/19/07

A.R.S. § 49-501.

Only A.2., B.1., C.,

F. and G. 

Unlawful open burning; exceptions; civil penalty; definitions

[ban on outdoor fires from May 1 to September 30;

deletion of recreational purpose exemption; no burn day

restrictions; penalty provision]

9/19/07

A.R.S. § 49-541.

Only 1.

Definitions [Area A] 8/9/01

ES - 8
Table ES-2 Continued

Maricopa County

Air Quality

Department Rules Description

Effective

Dates

310 Fugitive Dust from Dust-Generating Operations

Adopted 1/27/10 and submitted to EPA 4/12/10 [Notice of

Final Rulemaking 75 FR 78167; 12/15/10]

EPA approved

effective

1/14/11

310.01 Fugitive Dust From Non-Traditional Sources of Fugitive

Dust

Adopted 1/27/10 and submitted to EPA 4/12/10 [Notice of

Final Rulemaking 75 FR 78167; 12/15/10]

EPA approved

effective

1/14/11

314 Open Outdoor Fires and Indoor Fireplaces at Commercial

and Institutional Establishments

Adopted 3/12/08 and submitted to EPA 7/10/08 [Notice of

Final Rulemaking 74 FR 57612; 11/9/09]

EPA approved

effective

1/8/10

316 Nonmetallic Mineral Processing

Adopted 3/12/08 and submitted to EPA 7/10/08 [Notice of

Final Rulemaking 74 FR 58553; 11/13/09] 

EPA approved

effective

1/8/10 

Appendix C Fugitive Dust Test Methods

Adopted 3/26/08 and submitted to EPA 7/10/08 [Notice of

Final Rulemaking 75 FR 78167; 12/15/10]

EPA approved

effective

1/14/11

Maricopa County

Ordinance Description

Effective

Dates

P-26 Residential Woodburning Restriction

Adopted 3/26/08 and submitted to EPA 7/10/08; [Notice

of Final Rulemaking 74 FR 57612; 11/9/09]

EPA approved

effective

1/8/10

Appendices Description

Effective

Dates

Appendix C,

Exhibit 1

Arizona Revised Statutes Listed in Table 4-1

Appendix C,

Exhibit 2

Maricopa County Resolution to Evaluate Measures in the

MAG 2012 Five Percent Plan for PM-10 for the Maricopa

County Nonattainment Area

11/16/11

Appendix C,

Exhibit 3

Arizona Department of Environmental Quality Dust Action

General Permit

12/30/11

Appendix C,

Exhibit 4

Arizona Department of Environmental Quality Commitment

to Revise the MAG 2012 Five Percent Plan for PM-10 for

the Maricopa County Nonattainment Area if Necessary for

the Emerging and Voluntary Measure

ES - 9
open areas and vacant lots, open areas, vacant lots, unpaved parking lots, unpaved

roadways (including alleyways), easements, rights-of-way, access roads and trackout onto

paved surfaces from these activities.

Maricopa County Rule 316 (Nonmetallic Mineral Processing) regulates fugitive dust and

process dust emissions from sources and activities such as: mining, excavating,

separating, combining, crushing and grinding any nonmetallic mineral, asphaltic concrete

plants, raw material storage and distribution, concrete plants, bagging operations, open

storage piles, material handling, haul roads, and trackout onto paved surfaces from these

sources.

Emissions reduction credit is also taken for one new measure, the Dust Action General

Permit, which was passed by the Arizona Legislature in April 2011. In accordance with

A.R.S. § 49-457.05, this Dust Action General Permit identifies a series of Best

Management Practices (BMPs) for specific dust generating operations. When ADEQ’s

Maricopa County Dust Control Forecast predicts that a day is at high risk for dust

generation, those dust generating operations that are not already required to control dust

through a permit issued by the Arizona Department of Environmental Quality or the

Maricopa County Air Quality Department are expected to choose and implement at least

one BMP to reduce or prevent PM-10 emissions. Implementation of a BMP is expected to

occur as soon as practicable before and during the high risk event. Although the BMPs in

the Dust Action General Permit only apply to those sources that do not already have a

permit, even dust generating operations with an air quality permit are also expected to

implement the dust controls in their permit at the same time.

According to state statute, BMPs identified in the Dust Action General Permit are expected

to be employed absent the requirement to obtain an air quality permit. If the owner or

operator of a dust-generating operation is found by ADEQ’s Director to have failed to

choose and implement an applicable BMP as soon as practicable before and during a day

that is forecast to be at high risk of dust generation, then the owner or operator can be

required to obtain an Authorization to Operate under the Dust Action General Permit.

This new measure is expected to raise rule effectiveness for Rule 310.01 by one percent

during high wind hours and was fully implemented by January 1, 2012. Credit for this

measure is allowed under the EPA guidance, Incorporating Emerging and Voluntary

Measures in a State Implementation Plan. The measures used to demonstrate the annual

five percent reductions are also necessary to model attainment of the PM-10 standard

under high wind conditions at all monitors as expeditiously as practicable, which is 2012.

Table ES-3 shows the impact of the increases in rule effectiveness on PM-10 emissions

in 2008 through 2012. This table also quantifies the annual five percent reductions for 2008

through 2012. The total reduction in PM-10 emissions between 2007 and 2012 with the

increases in rule effectiveness is 16,089 tons, which represents a 27.2 percent reduction

in total 2007 base case emissions.

ES - 10
Table ES-3

2008-2012 PM-10 Emissions with Increased Rule Effectiveness

Source Category

2008 2009 2010 2011 2012

(tons/year)

POINT 150 133 127 128 135

AREA

Fuel combustion 1,301 1,307 1,311 1,316 1,328

Commercial cooking 993 998 1,001 1,005 1,014

Construction (includes windblown dust) 8,355 5,333 4,139 4,014 4,073

Tilling, harvesting and cotton ginning 893 893 893 893 893

Travel on unpaved farm roads 731 731 731 731 731

Livestock 261 261 261 261 261

Travel on unpaved parking lots 2,422 2,434 2,441 2,451 2,473

Offroad recreational vehicles 2,180 2,191 2,198 2,206 2,226

Leaf blowers 895 899 902 906 914

Windblown agriculture 448 448 448 448 448

Other windblown sources 3,938 3,788 3,788 3,788 3,639

Fires 497 497 497 497 497

Mining/quarrying (includes windblown dust) 476 401 355 356 369

Travel on industrial paved/unpaved roads 472 382 331 333 351

Other industrial sources 976 865 828 832 877

NONROAD

Aircraft 184 152 142 143 146

Airport ground support equipment 27 23 21 20 20

Locomotives 34 34 34 34 34

Other nonroad equipment 1,683 1,661 1,641 1,595 1,513

ONROAD

Exhaust 2,836 2,647 2,371 1,843 1,407

Tire wear 256 257 257 258 261

Brake wear 758 767 771 773 787

Paved roads 8,155 8,214 8,289 8,323 8,422

Unpaved roads and alleys 10,312 10,284 10,284 10,284 10,312

Totals 49,231 45,600 44,062 43,438 43,130

5% Reduction Targets (tons/year) 2,961 5,922 8,883 11,844 14,805

Actual Plan Reductions (tons/year) 9,987 13,618 15,157 15,781 16,089

ES - 11
Table ES-4 confirms that the annual five percent reduction requirements are met in 2008-

2012 and there is a surplus margin of benefit in each year. The total surplus in 2012 is

1,284 tons. This surplus is needed to model attainment at all monitors in the PM-10

nonattainment area by December 31, 2012. 

In accordance with the Clean Air Act, the MAG 2012 Five Percent Plan for PM-10 also

includes contingency measures. The contingency measures are required to achieve

emissions reductions beyond those measures relied upon to model attainment of the

standard and demonstrate progress toward attainment (five percent reductions, reasonable

further progress, and milestones). They are required to be undertaken without further

action by the State or the EPA Administrator if the area fails to make reasonable further

progress or meet the standard by the attainment date. EPA encourages early

implementation of contingency measures to reduce emissions as expeditiously as

practicable. 

EPA guidance indicates that contingency measures should provide emissions reductions

equivalent to one year of reasonable further progress. For the Five Percent Plan, one year

of reasonable further progress is equivalent to a reduction in PM-10 emissions of 3,218

tons.

The contingency requirement is met in the MAG 2012 Five Percent Plan by quantifying

projects that were completed in 2008-2011. A summary of the miles of roads, alleys and

shoulders impacted by the paving and stabilization, speed limit reduction, and rubberized

asphalt overlay projects that were quantified to meet the contingency requirement is

presented in Table ES-5. These PM-10 reduction projects were implemented in the PM-10

nonattainment area by twenty-one cities and towns, Maricopa County, Pinal County,

Arizona Department of Transportation and the Gila River Indian Community. All of the

projects for which credit was taken were open to traffic by September 2011.

The emissions reductions for all measures quantified to meet the contingency requirement

are summarized in Table ES-6. Table ES-6 includes the benefits of the PM-10 certified

street sweeping on freeways and arterials, as well as the projects completed in 2008-2011

that paved and stabilized unpaved roads, alleys and shoulders; reduced speed limits; and

overlaid highways with rubberized asphalt. The total PM-10 emissions reduction in 2012

is 3,439 tons, which exceeds the contingency target of 3,218 tons by 221 tons.

The total 2012 PM-10 emissions, with the air quality benefits from the wide variety of

control measures and contingency projects applied, are 39,691 tons per year (see Table

ES-7), which represents a reduction, relative to 2007 base case PM-10 emissions, of

19,527 tons or 33 percent. A pie chart of the 2012 nonattainment area PM-10 emissions

with the five percent measures and contingency projects applied is shown in Figure ES-4. 

For conformity analyses, the onroad mobile source emissions budget includes reentrained

dust from travel on paved roads; vehicular exhaust, tire wear, and brake wear; travel on

unpaved roads; and road construction. In 2012, the PM-10 emissions from these four

source categories total 54.9 metric tons per day for the PM-10 nonattainment area. This

represents the onroad mobile source emissions budget for conformity.

ES - 12
Table ES-4

PM-10 Emission Reductions and Five Percent Reduction Requirements

Year

5% Reduction

Requirement

Total PM-10 Emission

Reductions due to Increases

in Rule Effectiveness

Excess Benefit = Total PM-10

Emission Reductions minus 5%

Reduction Requirement

(tons/year) (tons/year) (tons/year) (%)

2008 2,961 9,987 7,026 237%

2009 5,922 13,618 7,696 130%

2010 8,883 15,157 6,274 71%

2011 11,844 15,781 3,937 33%

2012 14,805 16,089 1,284 9%

Table ES-5

Miles of Roads/Alleys/Shoulders in PM-10 Reduction Projects

Miles Impacted by Project Type 2008 2009 2010 2011

Total

2008-2011

Miles of dirt roads paved 41 18 8 16 83

Miles of dirt roads stabilized 39 39 36 31 145

Miles of dirt alleys paved 66 4 0 63 134

Miles of dirt alleys stabilized 164 106 124 106 501

Total miles of roads/alleys paved & stabilized 310 168 168 216 862

Miles of dirt shoulders paved 70 107 49 6 233

Miles of curb and gutter paved 19 0 0 0 19

Miles of dirt shoulders stabilized 235 236 236 200 906

Total miles of shoulders paved & stabilized 324 343 285 207 1,158

Miles of roads/alleys with lower speed limits 7 11 3 0 20

Miles of highway overlaid w/rubberized asphalt 13 0 0 0 13

ES - 13
Table ES-6

2008-2012 PM-10 Reductions to Meet Contingency Requirements

Completed Projects Implementing Entities

2008 20

Sweep streets with PM-10 certified sweepersContracted sweeping of freeways, ramps andfrontage roads - 100% compliant, effective 2/20/1025 PM-10 certified sweepers purchased with CMAQfunds: 1/1/07-12/31/09

ADOT 0 

Cities, towns 59 

Total for Street Sweeping 59 

Pave or stabilize existing public dirt roads andalleysPaving/stabilization projects completed in 2008-2011

Cities, towns, Maricopa and Pinal County,

and Gila River Indian Community 461 1

Total for Road/Alley Paving/Stabilization 461 1

Lower speed limits on dirt roads and alleysSpeed limits lowered in 2008-2011 Cities, towns, Maricopa County 4 

Total for Lower Speed Limits 4 

Pave or stabilize unpaved shouldersPaving/stabilization projects completed in 2008-2011 Cities, towns, Maricopa County 173 

Total for Shoulder Paving/Stabilizing 173 

Repave or overlay paved roads with rubberizedasphaltRubberized asphalt overlays completed in 2008-2011

ADOT 0 

Total for Overlays 0 

Total for Completed Projects 697 1

ES - 14
Table ES-7

2008-2012 PM-10 Emissions with Five Percent Plan Measures 

and Contingency Projects

Source Category 2008 2009 2010 2011 2012

POINT 150 133 127 128 135

AREA

Fuel combustion 1,301 1,307 1,311 1,316 1,328

Commercial cooking 993 998 1,001 1,005 1,014

Construction (includes windblown dust) 8,355 5,333 4,139 4,014 4,073

Tilling, harvesting and cotton ginning 893 893 893 893 893

Travel on unpaved farm roads 731 731 731 731 731

Livestock 261 261 261 261 261

Travel on unpaved parking lots 2,422 2,434 2,441 2,451 2,473

Offroad recreational vehicles 2,180 2,191 2,198 2,206 2,226

Leaf blowers 895 899 902 906 914

Windblown agriculture 448 448 448 448 448

Other windblown sources 3,938 3,788 3,788 3,788 3,639

Fires 497 497 497 497 497

Mining/quarrying (includes windblown dust) 476 401 355 356 369

Travel on industrial paved/unpaved roads 472 382 331 333 351

Other industrial sources 976 865 828 832 877

NONROAD

Aircraft 184 152 142 143 146

Airport ground support equipment 27 23 21 20 20

Locomotives 34 34 34 34 34

Other nonroad equipment 1,683 1,661 1,641 1,595 1,513

ONROAD

Exhaust 2,836 2,647 2,371 1,843 1,407

Tire wear 256 254 255 255 259

Brake wear 758 767 771 773 787

Paved roads 7,922 7,857 7,578 7,534 7,772

Unpaved roads and alleys 9,847 8,854 7,999 7,461 7,525

Totals 48,534 43,810 41,062 39,823 39,691

Total PM-10 Emissions Reduction 2007-2012: 19,527 tons, 33.0%

ES - 15
Figure ES-4

ES - 16
CHAPTER ONE

INTRODUCTION

Within the Maricopa County nonattainment area, the National Ambient Air Quality Standard

has not yet been attained for PM-10 particulate pollution. The area is classified as a

Serious Area under the Clean Air Act. On February 7, 1978, the Governor of Arizona

designated the Maricopa Association of Governments (MAG) as the lead planning

organization for Maricopa County that, together with the State is responsible for

determining which elements of the State Implementation Plan revision will be planned,

implemented, and enforced by State and local governments in Arizona. This designation

was made in accordance with the Clean Air Act Section 174(a). In 1992, the Arizona

Legislature recertified MAG as the regional planning agency in accordance with Section

174 of the 1990 Clean Air Act Amendments (A.R.S. Section 49-406 A.).

To meet the requirements of Section 189(d) of the Clean Air Act, the MAG 2007 Five

Percent Plan for PM-10 was submitted to the Environmental Protection Agency (EPA) by

the federal deadline of December 31, 2007. Collectively, the Five Percent Plan included

fifty-three control measures from the State, Maricopa County, and local governments. The

plan demonstrated that the measures would reduce PM-10 emissions by at least five

percent per year and demonstrated attainment of the PM-10 standard in 2010. The region

needed three years of clean data at the monitors in 2008, 2009 and 2010 in order for the

region to be in attainment of the PM-10 standard in 2010. There have been no violations

of the standard during stagnant conditions since the plan was submitted in 2007.

On September 9, 2010, EPA had published a notice of proposed partial approval and

disapproval of the plan in the Federal Register. There were two major reasons for the

proposed disapproval: the EPA nonconcurrence with four high wind exceptional events at

the West 43rd Avenue monitor in 2008 resulted in a violation, which negated the attainment

demonstration, and that the 2005 baseline emissions inventory was inaccurate since it

overestimated construction and other emissions.

On January 25, 2011, the Arizona Department of Environmental Quality (ADEQ) voluntarily

withdrew the MAG 2007 Five Percent Plan for PM-10 to address technical approvability

issues and include new information, such as the new EPA equation for paved road dust

emissions. While the plan was withdrawn, the measures continued to be implemented to

reduce PM-10.

Consequently, the MAG 2012 Five Percent Plan for PM-10 has been prepared to meet the

requirements in Section 189(d) of the Clean Air Act and improve air quality in the Maricopa

County nonattainment area. The plan is required to reduce PM-10 emissions by at least

five percent per year until the standard is attained as measured by the monitors. The

Clean Air Act specifies that the plan must be based upon the most recent emissions

inventory for the area and also include a modeling demonstration of attainment. The 2012

1 - 1
Five Percent Plan is designed to be a replacement for the 2007 plan that was withdrawn. 

The following narrative describes the historical background preceding the preparation of

the MAG 2012 Five Percent Plan for PM-10.

HISTORICAL BACKGROUND

Based upon the 1990 Clean Air Act Amendments, the Maricopa County nonattainment area

was initially classified as Moderate for PM-10 particulate pollution. However, on May 10,

1996, the nonattainment area was reclassified to Serious due to failure to attain the

particulate standard by December 31, 1994. The Serious Area reclassification was

effective on June 10, 1996.

The Revised MAG 1999 Serious Area Particulate Plan for PM-10 for the Maricopa County

Nonattainment Area was submitted to the Environmental Protection Agency in February

2000. On July 25, 2002, EPA published a notice of final approval for the plan. Collectively,

the plan contained approximately seventy-seven control measures from the State and local

governments. The plan demonstrated attainment of the PM-10 standard by December 31,

2006.

In order to be in attainment, the region needed three years of clean data at the monitors

for 2004, 2005, and 2006. However, there were numerous exceedances of the standard

in 2005 and 2006. On June 6, 2007, EPA published a final notice with its findings that the

Maricopa County nonattainment area had failed to attain the PM-10 standard by the federal

deadline of December 31, 2006. It then became necessary for MAG to prepare a Five

Percent Plan for PM-10.

In accordance with Section 189(d) of the Clean Air Act, a Five Percent Plan for PM-10 was

due to the Environmental Protection Agency by December 31, 2007. The plan was

required to reduce PM-10 emissions by at least five percent per year until the standard was

attained as measured by the monitors. The Clean Air Act specified that the plan must be

based upon the most recent emissions inventory for the area and also include a modeling

demonstration of attainment.

The MAG 2007 Five Percent Plan for PM-10 was submitted to EPA by the federal deadline

of December 31, 2007. Collectively, the Five Percent Plan for PM-10 included fifty-three

control measures from the State, Maricopa County, and local governments. The plan

demonstrated that the measures would reduce PM-10 emissions by at least five percent

per year and demonstrated attainment of the PM-10 standard in 2010. The region needed

three years of clean data at the monitors in 2008, 2009 and 2010 in order for the region to

be in attainment of the PM-10 standard in 2010. There have been no violations of the

standard during stagnant conditions since the plan was submitted in 2007.

In 2008, there were a number of exceedances of the twenty-four hour PM-10 standard due

to high winds in the Maricopa County nonattainment area. In June 2009, the Arizona

Department of Environmental Quality had submitted a preliminary demonstration to EPA

1 - 2
on the 2008 high wind events, since high wind exceptional events should not count against

the region. In November 2009, the ADEQ submitted final demonstrations for the

exceedances, including five at the West 43rd Avenue monitor.

On December 2, 2009, the Arizona Center for Law in the Public Interest filed a lawsuit

against EPA for failure to take action on the plan by June 30, 2009 in accordance with the

Clean Air Act. The Environmental Protection Agency reviewed the plan that had been

submitted two years ago and issues began to emerge. The plan was based upon a 2005

emissions inventory that was outdated with the downturn in the economy; the contribution

of emissions from the sources had changed. EPA had concerns with the Arizona

Department of Environmental Quality exceptional events documentation of four high wind

exceedances in 2008 at the West 43rd Avenue monitor.

On May 21, 2010, the Environmental Protection Agency sent a letter to the ADEQ

indicating that EPA did not concur with the ADEQ documentation for the four high wind

exceptional events at the West 43rd Avenue monitor. As a result, the four exceedances

would constitute a violation at the monitor and the region would not have its first of three

years of clean data needed to attain the standard by 2010.

On September 3, 2010, the Environmental Protection Agency signed a notice to propose

partial approval and disapproval of the MAG 2007 Five Percent Plan for PM-10 based on

the timetable in the consent decree with the Arizona Center for Law in the Public Interest. 

On September 9, 2010, the notice was published in the Federal Register. EPA proposed

disapproval of the emissions inventories, attainment demonstration, five percent annual

reductions in emissions, reasonable further progress and milestones, contingency

measures, and the 2010 motor vehicle emissions budget. EPA proposed limited approval

and disapproval for agricultural regulations. EPA proposed approval of the Arizona

Revised Statutes that mandated twenty measures in the plan and the Agricultural Best

Management Practices Guidance Booklet and Pocket Guide. Based upon the consent

decree, EPA indicated that a notice of final action would be signed by January 28, 2011.

According to EPA, there were two major reasons for the proposed partial disapproval of the

plan:

1. EPA contended that the modeling attainment demonstration in the plan cannot be

approved if actual monitor data show that the area cannot attain the standard by the

attainment date of December 31, 2010. This was directly resultant from the EPA

nonconcurrence with the four high wind exceptional events at the West 43rd Avenue

monitor in 2008. The four exceedances constituted a violation of the standard. EPA

further indicated that it was not necessary to review the exceptional event claims for

2009 since the region did not have its first year of clean data in 2008 needed to

attain the standard by 2010.

2. EPA contended that the 2005 baseline emissions inventory was inaccurate since it

overestimated construction emissions and other emissions. The 2005 emissions

1 - 3
inventory prepared by the Maricopa County Air Quality Department was the

foundation upon which the plan was developed. The emissions inventory was the

basis for the air quality modeling prepared by MAG for the five percent reductions

in emissions; impact of the plan measures and contingency measures; reasonable

further progress (annual incremental emissions reductions to ensure attainment);

milestone demonstrations every three years; and the attainment demonstration.

On January 25, 2011, the Arizona Department of Environmental Quality withdrew the MAG

2007 Five Percent Plan for PM-10 to address the technical approvability issues identified

by EPA and include new information, such as the new EPA equation for paved road dust

emissions. The new EPA equation was more accurate and would improve the emissions

inventory. Although the plan was withdrawn, the measures continued to be implemented

to reduce PM-10.

On February 14, 2011, the Environmental Protection Agency published a final notice in the

Federal Register to make a Finding of Failure to Submit as a result of the withdrawal of the

2007 Five Percent Plan for PM-10. The Finding of Failure to Submit was effective on

February 14, 2011. If a new complete plan is not submitted within eighteen months of the

finding, the Clean Air Act sanction of tighter controls on major industries (two to one offsets)

would be imposed by August 14, 2012. If a complete plan is not submitted within twentyfour months of the finding, the federal highway sanction and a federal implementation plan

would be imposed by February 14, 2013. The submittal of a new plan and a completeness

determination by EPA will stop the sanctions clocks. A plan approval action by EPA will

stop the imposition of a federal plan.

OUTLINE OF THE MAG 2012 FIVE PERCENT PLAN FOR PM-10

The purpose of this document is to present the MAG 2012 Five Percent Plan for PM-10 for

the Maricopa County Nonattainment Area. The plan contains a variety of existing control

measures and projects that have been implemented to reduce PM-10 and a new measure

designed to reduce PM-10 during high winds.

The MAG 2012 Five Percent Plan for PM-10 is composed of the following major sections:

1. Introduction (This Chapter) - Includes a general discussion of historical

background and the outline of the MAG 2012 Five Percent Plan for PM-10.

2. Description of the Nonattainment Area - Includes a description of the

nonattainment area; geography and climatic conditions.

3. Assessment of Air Quality Conditions - Includes a discussion of the formation

of particulate pollution; PM-10 emissions inventory; and air quality monitoring

data and trend analysis.

4. The Adopted Plan - Includes a table of statutes, rules, ordinance, and

1 - 4
appendices for the plan; Maricopa County Resolution to Evaluate Measures

in the MAG 2012 Five Percent Plan for PM-10 for the Maricopa County

Nonattainment Area; Arizona Department of Environmental Quality Dust

Action General Permit; Arizona Department of Environmental Quality

Commitment to Revise the MAG 2012 Five Percent Plan for PM-10 for the

Maricopa County Nonattainment Area if Necessary for the Emerging and

Voluntary Measure; tracking plan implementation; and assurances that the

State has the authority to implement the measures in the plan.

5. Demonstration of Annual Five Percent Reductions in PM-10 Emissions -

Includes a discussion of the measures quantified to meet the annual five

percent requirement and demonstration for the five percent reduction

requirement.

6. Attainment Demonstration - Includes a discussion of the Salt River area

modeling; PM-10 nonattainment area modeling; reasonable further progress,

contingency requirements; onroad mobile source emissions budget for

conformity; expeditious attainment; and attainment date.

1 - 5
CHAPTER TWO

DESCRIPTION OF THE NONATTAINMENT AREA

The Maricopa County nonattainment area for particulates was formally designated in April

1974. As defined in the 1977 Clean Air Act, the term nonattainment area refers to locations

which exceed any national ambient air quality standard for any pollutant based upon the

data collected through air quality monitoring. A general description of the Maricopa County

nonattainment area, including a discussion of the boundaries of the area and the

geography and climatic conditions is provided below. 

NONATTAINMENT AREA BOUNDARIES

When the Environmental Protection Agency promulgated the PM-10 National Ambient Air

Quality Standard on July 1, 1987, there was little PM-10 monitoring data available for EPA

to use in determining the nonattainment area boundaries. In the August 7, 1987 Federal

Register, EPA promulgated its policy of categorizing areas of the country into three groups

based on the probability that an area’s existing State Implementation Plan (SIP) would

need to be revised to protect or attain the new PM-10 standard. Group I areas were those

areas which EPA identified as having a strong likelihood of violating the PM-10 standard

and requiring substantial SIP revisions. 

In the August 7, 1987 Federal Register, EPA identified the Group I area in Maricopa

County, Arizona as the Phoenix Planning Area. In the October 31, 1990 Federal Register,

EPA published technical corrections modifying the boundaries of certain areas of concern. 

The designation of the nonattainment area boundary is documented in the EPA letter dated

September 11, 1991. 

In the October 1990 Federal Register the area was defined as “The rectangle determined

by, and including, T6N, R3W; T6N, R7E; T2S, R3W; T2S, R7E; T1N, R8E.” The

nonattainment area is generally encompassed by 259th Avenue on the west, Hunt Highway

on the south, Meridian Road on the east and a boundary approximately six miles north of

Carefree Highway on the north (see Figure 2-1). This area contains portions of the

municipal planning areas for twenty-two cities and towns in Maricopa County, the Fort

McDowell, Gila River, and Salt River Pima-Maricopa Indian Communities, as well as

unincorporated areas under the jurisdiction of Maricopa County. The PM-10 nonattainment

area also contains a six by six mile section in Pinal County that encompasses a portion of

the Apache Junction Municipal Planning Area which includes unincorporated areas under

the jurisdiction of Pinal County.

When determining the new PM-10 nonattainment area in 1987, the Environmental

Protection Agency included the City of Apache Junction, a small eastern portion of Apache

Junction lies in Maricopa County and the western portion lies in Pinal County. Pinal County

2 - 1
2 - 2
worked with the Arizona Department of Environmental Quality on a separate PM-10 plan

for that portion of the nonattainment area. 

GEOGRAPHY AND CLIMATIC CONDITIONS

Due to its valley location, the nonattainment area has an elevation of 1,105 feet above

mean sea level (MSL) and is almost completely surrounded by mountains. The Salt River

Mountains are located on the southern border of the nonattainment area and rise to an

elevation of 2,507 feet above MSL. To the northwest, the Phoenix Mountains have an

elevation of 2,310 feet above MSL. The Estrella Mountains are located to the southwest

and have an elevation of 3,320 feet above MSL. On the western boundary, the White Tank

Mountains rise to an elevation of 4,026 feet above MSL and on the eastern boundary, the

Superstition Mountains rise to an elevation of 4,620 feet above MSL. 

There are five main rivers that run through the nonattainment area: the Salt River, Agua

Fria River, Gila River, New River, and Verde River. These river beds are generally dry,

except during torrential rainfall, which happens infrequently.

The climate in the nonattainment area is arid continental, experiencing extreme ranges in

daily temperatures. Temperatures range from a mean of 55.5 degrees Fahrenheit in

December to a mean of 94.8 degrees Fahrenheit in July; the annual mean temperature is

74.2 degrees Fahrenheit. The sun shines approximately 85 percent of the time and the

annual average rainfall is 8.29 inches. Most of the rainfall occurs from December through

March and during the months of July and August. (Source: National Oceanic &

Atmospheric Administration National Data Centers.)

In general, the morning direction for the prevailing winds in the nonattainment area is from

east (southeast) to west (southwest). However, wind direction can change in the afternoon

to a more westerly direction. The average annual wind speed is 6.2 miles per hour.

2 - 3
CHAPTER THREE

ASSESSMENT OF AIR QUALITY CONDITIONS

Within the Maricopa County nonattainment area, PM-10 is a problem throughout the year. 

Particulate air pollution is composed of solid particles or liquid droplets which are small

enough to remain suspended in the air. The smaller the size, the more likely the particles

are to reach the innermost portions of the lungs and cause damage. Major concerns for

human health from exposure to particle pollution include: increased respiratory symptoms,

such as irritation of the airways, coughing, or difficulty breathing; decreased lung function;

aggravated asthma; development of chronic bronchitis; irregular heartbeat; nonfatal heart

attacks; and premature death in people with heart or lung disease. The elderly, children,

and people with heart and lung disease are especially sensitive to the effects of particulate

matter. Particles that are 2.5 micrometers in diameter and smaller (PM-2.5) can lodge

deep in the lungs and are believed to be the largest health risk. The EPA designated

Maricopa County as an attainment area for PM-2.5 in September 2005. 

In order to effectively reduce PM-10, it is important to assess air quality conditions in the

PM-10 nonattainment area. This chapter presents a discussion of PM-10 formation, the

Maricopa County Air Quality Department 2005 Periodic Emissions Inventory for PM-10 for

the Maricopa County, Arizona, Nonattainment Area, and air quality monitoring data.

FORMATION OF PM-10 PARTICULATE POLLUTION

The formation of PM-10 particulate pollution is dependent upon several factors. Among

these factors are stagnant air masses, severe temperature inversions in the winter, high

winds from thunderstorms and frontal systems, and fine, silty soils characteristic of desert

locations. In the nonattainment area, high PM-10 concentrations generally occur in

September through March, on days with stagnant or near-stagnant conditions. High PM-10

concentrations can also occur during thunderstorm outflows and frontal systems which

create high winds that entrain soil particles from bare surfaces. 

The PM-10 in the arid Southwest largely consists of coarse particles (i.e., aerodynamic

diameter greater than 2.5 microns but less than or equal to 10 microns) which are typically

crustal in nature and derive mainly from windblown dust, resuspended road dust (from

paved and unpaved roads), unpaved parking lots, disturbed vacant land, mining operations,

construction, and agricultural activities (e.g., tilling and harvesting, travel on unpaved farm

roads). Other components of particulate matter, such as sulfates, nitrates, and organic and

elemental carbons, are typically found in the fine fraction of particulate matter (i.e.,

aerodynamic diameter less than or equal to 2.5 microns), but can also contribute to coarse

particulate matter. Previous analyses of PM-2.5 data in the Phoenix area have shown that

mobile source exhaust, burning, and industrial sources are important constituents of PM2.5. The co-located PM-10 and PM-2.5 monitors at the Durango Complex site indicate that

PM-2.5 readings on days with high PM-10 concentrations range from 6 to 15 percent of the

3 - 1
PM-10 on high wind days and 14 to 22 percent on low wind days. Therefore, the PM-10

problem in the nonattainment area is largely attributable to coarse particles, comprised

primarily of geologic material (MAG, 2008).

PM-10 EMISSIONS INVENTORY

The Clean Air Act requires a comprehensive, accurate, and current inventory of actual

emissions from all sources. In June 2011, the Maricopa County Air Quality Department

compiled a revised 2008 periodic emissions inventory which includes primary emissions

of PM-10 and PM-2.5 as well as three particulate matter precursors: nitrogen oxides (NOx),

sulfur dioxides (SOx) and ammonia (NH3). The inventory provides emission estimates for

Maricopa County and the PM-10 nonattainment area. Maricopa County encompasses

approximately 9,223 square miles and the PM-10 nonattainment area is about

2,888 square miles. 

Emission sources included in the 2008 Periodic Emissions Inventory for PM-10 are Point

Sources, Area Sources, Nonroad Mobile Sources, Onroad Mobile Sources, and Biogenic

Sources. The inventory provides the typical daily emissions and annual emissions for

these categories. Table 3-1 includes a breakdown of annual emissions for the PM-10

nonattainment area. 

The point source category includes stationary sources which emit a significant amount of

pollution into the air. Examples of point sources include power plants, industrial processes,

and large manufacturing facilities. Area sources are stationary sources which are too small

or too numerous to be treated as point sources. Examples include residential wood

burning, commercial cooking, waste incineration, and wildfires. Nonroad mobile sources

include off-highway vehicles and engines that move or are moved in a 12-month period

such as construction and mining equipment, lawn and garden equipment, and aircraft. The

onroad mobile sources category includes exhaust, paved road fugitive dust, unpaved road

fugitive dust, tire wear, and break wear. Biogenic sources (plant life) were estimated using

the Model of Emissions of Gases and Aerosols from Nature (MEGAN) Biogenic Emissions

Inventory System. Among the chemical species included in the MEGAN Model, only NOx

is attributable to particulate matter formation and therefore only NOx emissions are

included in the 2008 inventory.

Collectively, the source categories are estimated to have contributed 48,148.00 (English)

tons of PM-10; 13,512.16 tons of PM-2.5; 109,662.87 tons of NOx; 1,808.84 tons of SOx;

and 12,458.87 tons of NH3 in calendar year 2008 within the PM-10 nonattainment area. 

A complete description of these sources and the corresponding methodology used to

calculate the emissions for 2008 are included in the 2008 Periodic Emissions Inventory for

PM-10 for the Maricopa County, Arizona, Nonattainment Area, Revised June 2011. This

inventory is provided in Appendix A, Exhibit 1. Projected emission inventories for years

2007 through 2012 are based upon the 2008 periodic inventory for PM-10 and are provided

in Chapter Five.

3 - 2
Table 3-1

Annual Emissions for the PM-10 Nonattainment Area from All Source Categories

Included in the 2008 Periodic Emissions Inventory for PM-10

(English Tons/Year)

Source Category PM-10 PM-2.5 NOx SOx NH3

POINT TOTAL 149.84 132.94 1,317.85 28.76 132.18

AREA

Fuel Combustion 1,300.65 1,268.35 12,248.07 895.83 51.11

Industrial Processes 10,655.39 2,771.19 360.48 129.58 1,724.27

Waste Treatment/Disposal 120.77 95.42 50.30 56.85 1,494.12

Miscellaneous Area Sources 12,444.36 2,143.52 115.94 29.74 7,693.04

AREA TOTAL 24,521.17 6,278.48 12,774.79 1,112.00 10,962.54

NONROAD MOBILE

Agricultural 15.13 14.67 161.35 0.06 0.30

Airport Ground Support 26.99 26.48 578.95 26.22 ---

Commercial 117.66 112.69 1,391.61 2.39 21.06

Construction and Mining 1,249.88 1,210.00 14,666.42 6.55 27.85

Industrial 101.42 98.71 2,586.39 3.21 56.09

Lawn and Garden 183.02 169.48 801.41 3.17 19.71

Pleasure Craft 7.02 6.48 59.03 0.64 1.32

Railway Maintenance 1.13 1.10 9.26 0.00 0.02

Recreational 7.68 7.08 10.76 0.07 0.35

Aircraft 183.80 177.61 2,620.31 316.00 ---

Locomotives 34.16 31.88 907.76 9.11 2.16

NONROAD MOBILE TOTAL 1,927.89 1,856.18 23,793.26 367.42 128.87

ONROAD MOBILE

Exhaust, Tire Wear and Brake Wear 3,144.17 2,300.80 71,444.20 300.66 1,235.28

Paved Road Fugitive Dust 6,694.22 1,774.76 --- --- ---

Unpaved Road Fugitive Dust 11,710.70 1,169.00 --- --- ---

ONROAD MOBILE TOTAL 21,549.09 5,244.56 71,444.20 300.66 1,235.28

BIOGENIC TOTAL --- --- 332.77 --- ---

TOTAL ALL SOURCES 48,148.00 13,512.16 109,662.87 1,808.84 12,458.87

Notes: Totals shown may not equal the sum of individual values due to independent rounding.

3 - 3
A pie chart of the 2008 PM-10 annual emissions in the PM-10 nonattainment area is shown

in Figure 3-1. The largest single source category is unpaved road fugitive dust at 24

percent. Construction activities contribute a combined 17 percent (residential, commercial,

road, and other earthmoving), while paved road fugitive dust contributes 14 percent. 

Windblown dust accounts for 10 percent of the annual inventory. Onroad mobile vehicle

exhaust, tire wear and brake wear contribute seven percent. The remaining categories in

the figure individually contribute six percent or less to the total annual emissions.

AIR QUALITY MONITORING DATA AND TREND ANALYSIS

In addition to identifying sources of PM-10 emissions, it is important to examine the impact

of these emissions on the ambient concentrations. This section includes discussions of the

National Ambient Air Quality Standards (NAAQS) for PM-10 and the air quality data

recorded by the areawide monitoring network.

The 24-hour PM-10 standard is 150 micrograms per cubic meter (ug/m3

). The standard is

attained when the expected number of exceedances per year at each monitoring site is less

than or equal to 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 past three years. At some sites, PM-10 sampling is scheduled less frequently than

every day. To account for this, an adjustment must be made to the data collected at each

site to estimate the number of exceedances in a calendar year. Due to possible seasonal

imbalance, the adjustment is made quarterly. The estimate of the expected number of

exceedances for the quarter is equal to the observed number of exceedances plus an

increment associated with the missing data. The expected number of exceedances is then

estimated by averaging the annual estimates over the three-year period. Due to the

rounding criteria used by EPA, a recorded average PM-10 concentration must be under

155 ug/m3 to not be considered an exceedance and the three-year expected exceedance

rate for any site must be less than 1.05 for the region to be in attainment of the 24-hour

standard. The annual PM-10 standard of 50 ug/m3 was revoked by EPA effective

December 18, 2006.

In order to determine the extent of the regional PM-10 pollution problem, it is necessary to

examine the air quality data collected by the areawide monitoring network. A total of 27

criteria pollutant monitoring stations are currently operated by the Maricopa County Air

Quality Department (MCAQD), Pinal County Air Quality Control District (PCAQCD), and

Arizona Department of Environmental Quality (ADEQ) in the PM-10 nonattainment area. 

Sixteen of these sites monitor PM-10. The Buckeye monitoring site is located just outside

the western boundary of the nonattainment area and also monitors PM-10. Site-specific

information regarding the PM-10 monitoring stations is provided in Table 3-2, and the

geographic location of each site is indicated in Figure 3-2. 

As mentioned previously, not all PM-10 samples are collected every day. Most of the

exceedances prior to 2004 were recorded by filter-based monitors that measured PM-10 

3 - 4
Figure 3-1

3 - 5
Table 3-2

PM-10 Monitoring Stations

FIGURE 3-2

MAP INDEX SITE ADDRESS

OPERATING

AGENCY

SAMPLING

SCHEDULE

AJ

Apache Junction

Fire Station

3955 E. Superstition

Blvd. PCAQCD Continuous

BE* Buckeye 26449 W. 100th Dr. MCAQD Continuous

CP Central Phoenix 1645 E. Roosevelt MCAQD Continuous

DC Durango Complex

2702 RC Esterbrooks

Blvd. MCAQD Continuous

DY Dysart 16825 N. Dysart Rd. MCAQD/ADEQ Continuous

GL Glendale 6001 W. Olive MCAQD Continuous

GR Greenwood 1128 N. 27th Ave. MCAQD Continuous

HI Higley 15400 S. Higley Rd. MCAQD Continuous

JLG JLG Supersite 4530 N. 17th Ave. ADEQ Continuous

ME Mesa 310 S. Brooks MCAQD 1 in 6 day

NP North Phoenix 601 E. Butler Dr. MCAQD Continuous

SP South Phoenix 33 W. Tamarisk MCAQD Continuous

SS South Scottsdale 2857 N. Miller Rd. MCAQD 1 in 6 day

WC West Chandler 275 S. Ellis MCAQD Continuous

WF West 43rd Avenue 3940 W. Broadway MCAQD Continuous

WP West Phoenix 3847 W. Earll MCAQD Continuous

ZH Zuni Hills 10851 W. Williams Rd. MCAQD Continuous

* The Buckeye monitor is located outside the western boundary of the PM-10 nonattainment area.

Sources: Pinal County Air Quality Website; Arizona Department of Environmental Quality State of Arizona

Air Monitoring Network Plan for the Year 2011; Maricopa County Air Quality Department 2010 Air

Monitoring Network Review. 

3 - 6
3 - 7
concentrations every sixth day. Since 2004, the filter-based monitors that have exceeded

the PM-10 standard have been replaced with monitors that measure PM-10 concentrations

continuously. Currently, within the nonattainment area samples are collected every sixth

day at two of the PM-10 monitoring stations while 14 sites now sample continuously. The

sampling schedule for each site is provided in Table 3-2. 

One method of assessing the overall air quality of a region is to examine the concentrations

measured at the monitoring stations. The trend in the number of 24-hour PM-10

exceedance days is presented in Figure 3-3. Tables 3-3 and 3-4 provide detailed

information on exceedances of the 24-hour PM-10 standard for the past six years. 

It is important to note that beginning in 2004, the Arizona Department of Environmental

Quality (ADEQ) began flagging exceptional events. This is an uncontrollable natural event

(e.g., high winds, wildfires) or a human-caused event that is not expected to recur at a

given location (e.g., fireworks). The data and a demonstration of the event are submitted

to EPA for concurrence. Once approved, the data is not used in determining compliance

with the PM-10 standard. Tables 3-3 and 3-4 note the exceptional events that have

occurred since 2005. 

Figure 3-3, which presents the trend in number of exceedance days of the 24-hour

standard from 1988 to 2010, shows a noticeable increase in the number of exceedance

days since 1994. Between 1988 and 1993, there were zero to three exceedance days per

year. The number of exceedance days increased from zero in 1993 to 10 in 1994. This

increase in 1994 is attributable to the installation of a new site (Salt River monitor). This

site was located in the Salt River Area and sources nearby included sand and gravel, metal

recycling, precast manufacturing, and paved and unpaved haul road. The Salt River site

was shut down as of December 31, 2002. Efforts were made to find a suitable replacement

site with comparable PM-10 concentrations and industrial emissions. The West 43rd

Avenue site was identified and began operating in the Salt River Area in the second quarter

of 2002. 

There was also an increase in the number of exceedance days from November 2005

through March 2006. During this period, the region experienced stagnant conditions and

an unusually long period with no rain, which may have contributed to the exceedances. 

Exceedances have also occurred since 2006; however, the majority of these have been

flagged as high wind exceptional events. 

Tables 3-3 and 3-4 list the date, day, reading, and location of each exceedance of the

24-hour PM-10 standard recorded from 2005 to 2010, including the data flagged as

exceptional events. In 2005, there were 19 exceedance days in the region. The number

increased to 27 exceedance days in 2006 with six being exceptional events. The EPA

concurred with four of the exceptional event days and took no action on the remaining two. 

In both 2007 and 2008 there were 11 days where the region exceeded the PM-10 standard. 

Most of these exceedances were exceptional events where EPA has yet to take 

3 - 8
Figure 3-3

Number of 24-Hour PM-10 Exceedance Days

Notes: -The Arizona Department of Environmental Quality began flagging exceptional events in 2004. 

-The chart includes exceedance days at the Buckeye monitor, which is located outside the PM-10 nonattainment ar-On July 19, 2007, the exceedance at the Buckeye monitor was not associated with the exceptional event that also 

Sources: 1988 - 1997 - Revised MAG 1999 Serious Area Particulate Plan for PM-10 for the Maricopa County Nonattainme

1998 - 2010 - EPA Air Quality System.

27

19 18

13 11 

10

7 8 

6

3 4 3 4

2 2 0 0 0 0

3 - 9
Table 3-3

Exceedances of the 24-Hour PM-10 Standard, 2005 to 2007

2005 2006 2007

DATE DAY READING LOCATION DATE DAY READING LOCATION DATE DAY READING LOCATION

4/4/05 Mon 172 WF 1/10/06 Tue 155 DC 3/27/07 Tue 227+ WF

6/21/05 Tue 157 BE1 1/10/06 Tue 190 WF 4/12/07 Thu 171+ SP

11/1/05 Tue 166 WF 1/11/06 Wed 168 DC 4/12/07 Thu 202+ WF

11/2/05 Wed 173 WF 1/11/06 Wed 165 WF 5/4/07 Fri 196+ WF

11/3/05 Thu 163 DC 1/12/06 Thu 169 DC 6/6/07 Wed 180+ HI

11/10/05 Thu 165 WF 1/12/06 Thu 169 WF 6/6/07 Wed 225+ WF

11/17/05 Thu 155 DC 1/13/06 Fri 156 WF 7/19/07 Thu 194 BE1

11/18/05 Fri 169 BE1 1/19/06 Thu 183 DC 7/19/07 Thu 267+ CP

11/22/05 Tue 189 DC 1/19/06 Thu 183 WF 7/19/07 Thu 272+ CL2

11/22/05 Tue 173 WF 1/24/06 Tue 170 HI 7/19/07 Thu 199+ HI

11/23/05 Wed 164 DC 2/8/06 Wed 183 WF 7/19/07 Thu 521+ JLG

11/23/05 Wed 175 WF 2/9/06 Thu 171 DC 7/19/07 Thu 177+ WF

12/1/05 Thu 158 DC 2/9/06 Thu 204 WF 8/13/07 Mon 159+ SP

12/2/05 Fri 164 DC 2/13/06 Mon 159 BE1 8/16/07 Thu 195+ HI

12/2/05 Fri 194 WF 2/14/06 Tue 272 BE1 8/16/07 Thu 214+ WF

12/12/05 Mon 198 BN 2/15/06 Wed 157 DC 8/23/07 Thu 230+ HI

12/12/05 Mon 206 DC 2/15/06 Wed 201 WF 10/21/07 Sun 312+ CL2

12/12/05 Mon 172 GR 2/17/06 Fri 191 BE1 10/24/07 Wed 174+ HI

12/12/05 Mon 232 WF 3/10/06 Fri 240+ DC 11/15/07 Thu 165+ BE1

12/12/05 Mon 155 WP 3/10/06 Fri 166+ GR 11/15/07 Thu 155+ DC

12/13/05 Tue 165 DC 3/10/06 Fri 260+ WF

12/13/05 Tue 167 WF 4/14/06 Fri 211++ BE1

12/14/05 Wed 180 DC 4/14/06 Fri 189++ CP

12/14/05 Wed 176 WF 4/14/06 Fri 253++ DC

12/15/05 Thu 155 DC 4/14/06 Fri 212++ GR

12/21/05 Wed 200 DC 4/14/06 Fri 221++ HI

12/21/05 Wed 200 WF 4/14/06 Fri 312++ WF

12/22/05 Thu 178 DC 4/14/06 Fri 177++ WP

12/22/05 Thu 167 WF 4/15/06 Sat 187++ CP

12/23/05 Fri 157 DC 4/15/06 Sat 179++ DC

12/23/05 Fri 156 WF 4/15/06 Sat 170++ GR

4/15/06 Sat 274++ HI

4/15/06 Sat 191++ WF

5/22/06 Mon 174++ WF

6/2/06 Fri 159 WF

6/6/06 Tue 155++ HI

10/5/06 Fri 165+ HI

11/16/06 Thu 163 WF

11/17/06 Fri 174 WF

11/27/06 Mon 164 WF

12/5/06 Tue 173 WF

12/6/06 Wed 167 DC

12/6/06 Wed 159 WF

12/7/06 Thu 174 DC

12/7/06 Thu 159 WF

12/14/06 Thu 163 WF

12/15/06 Thu 177 WF

1

 The Buckeye monitor is located outside the PM-10 nonattainment area.

2

 The Coyote Lakes monitor was a special purpose monitoring site that was shut down in February 2009.

+ Exceptional events where EPA took no action.

++ Exceptional events with EPA concurrence.

Source: EPA Air Quality System.

3 - 10
Table 3-4

Exceedances of the 24-Hour PM-10 Standard, 2008 to 2010

2008 2009 2010

DATE DAY READING LOCATION DATE DAY READING LOCATION DATE DAY READING LOCATION

3/2/08 Sun 159+ BE1 3/22/09 Sun 198** WF 10/15/10 Fri 158 GR

3/14/08 Fri 250* WF 3/26/09 Thu 209** WF

4/30/08 Wed 172* WF 4/3/09 Fri 213** WF

5/21/08 Wed 278* WF 7/17/09 Fri 400** BE1

6/4/08 Wed 203+ BE1 7/17/09 Fri 161** DC

6/4/08 Wed 186+ CL2 7/17/09 Fri 275** HI

6/4/08 Wed 193* WF 7/17/09 Fri 169** SP

7/1/08 Tue 172+ BE1 7/17/09 Fri 185** WF

7/4/08 Fri 223+ BE1 7/18/09 Sat 213** BN

10/11/08 Sat 161+ SP 7/18/09 Sat 439** BE1

10/22/08 Wed 167+ CL2 7/18/09 Sat 277** DC

11/7/08 Fri 247 DC 7/18/09 Sat 227** DY

11/9/08 Sun 169+ DC 7/18/09 Sat 196** GL

11/9/08 Sun 230+ SP 7/18/09 Sat 229** GR

11/9/08 Sun 247+ WF 7/18/09 Sat 250** SP

7/18/09 Sat 185** WC

7/18/09 Sat 317** WF

7/18/09 Sat 210** WP

9/3/09 Thu 160** SP

9/3/09 Thu 174** WF

10/27/09 Tue 166** BE1

10/27/09 Tue 157** DC

10/27/09 Tue 177** HI

10/27/09 Tue 220** WC

10/27/09 Tue 188** WF

1

 The Buckeye monitor is located outside the PM-10 nonattainment area.

2

 The Coyote Lakes monitor was a special purpose monitoring site that was shut down in February 2009.

+ Exceptional events where EPA took no action.

 * Exceptional events where EPA did not concur.

** Exceptional events where EPA concurrence is pending.

Source: EPA Air Quality System.

3 - 11
action. However, EPA has indicated that it does not concur with four high wind exceptional

events at the West 43rd Avenue site in 2008, resulting in a violation of the PM-10 standard. 

All of the exceedances in 2009 have been flagged as exceptional events and EPA

concurrence is pending. In 2010, only one exceedance of the 24-hour PM-10 standard

occurred, which did not constitute a violation.

In summary, the region has experienced a number of exceptional events in recent years. 

However, due to EPA nonconcurrence with four events at the West 43rd Avenue monitor

in 2008, the region was unable to attain the PM-10 standard in 2010. The exceedances

in 2009 have been flagged as exceptional events and only one exceedance occurred in

2010. Therefore, approval of the 2009 exceptional events would give the region two years

of clean data.

3 - 12
REFERENCES

MAG, 2008. PM-10 Source Attribution and Deposition Study. March, 2008.

3 - 13
CHAPTER FOUR

THE ADOPTED PLAN AND IMPLEMENTATION SCHEDULE FOR

THE MAG 2012 FIVE PERCENT PLAN FOR PM-10

The new MAG 2012 Five Percent Plan for PM-10 contains a wide variety of existing control

measures and projects that have been implemented to reduce PM-10 and a new measure

designed to reduce PM-10 during high risk conditions, including high winds. While the

2007 Five Percent Plan was withdrawn, a wide range of control measures in that plan

continue to be implemented to reduce PM-10 and are being resubmitted. Table 4-1

includes the Arizona Statutes, Maricopa County Rules, a Maricopa County Ordinance, and

Appendices for the resubmitted measures and a new high risk measure to be approved into

the MAG 2012 Five Percent Plan for PM-10 for the Maricopa County Nonattainment Area. 

The Arizona Revised Statutes listed in Table 4-1 are included in Appendix C, Exhibit 1. 

The 2012 Five Percent Plan also includes contingency measures that were implemented

early such as PM-10 certified street sweeping on freeways and arterials, as well as the

projects completed in 2008-2011 that paved and stabilized unpaved roads, alleys and

shoulders; reduced speed limits; and overlaid highways with rubberized asphalt.

As described in Table 4-1, the Arizona Statutes, Maricopa County Rules, and Maricopa

County Ordinance include requirements to reduce PM-10 emissions from a broad range

of sources. The requirements apply to unpaved roads and shoulders, leaf blowers,

unpaved parking lots, vacant lots, sweeping streets with certified sweepers, off-road vehicle

use, open and recreational burning, residential woodburning, covered vehicle loads, dust

generating operations, nonmetallic mineral processing, and other unpermitted sources.

It is also important to note that the Environmental Protection Agency (EPA) has approved

Maricopa County Rules 310 and 310.01 in 2010 and Rule 316 in 2009, as part of the State

Implementation Plan. Compliance with these rules has increased every year since 2007.

These Maricopa County rules reduce emissions from a wide variety of sources and apply

to the Maricopa County area. Maricopa County Rule 310 (Fugitive Dust from DustGenerating Operations) regulates fugitive dust emissions from sources and activities such

as: land clearing, earthmoving, weed abatement, excavating, construction, demolition, bulk

material handling, storage and transporting operations, outdoor equipment, motorized

machinery, staging areas, parking areas, material storage areas, haul roads, disturbed

surface areas, initial landscapes and trackout onto paved surfaces from these sources.

Maricopa County Rule 310.01 (Fugitive Dust from Non-Traditional Sources of Fugitive

Dust) regulates fugitive dust emissions from sources and activities such as: vehicle use in

open areas and vacant lots, open areas, vacant lots, unpaved parking lots, unpaved

roadways (including alleyways), easements, rights-of-way, access roads and trackout onto

paved surfaces from these activities.

4 - 1
Table 4-1

Arizona Statutes, Maricopa County Rules, Maricopa County Ordinance, 

and Appendices to be Approved into the MAG 2012 Five Percent Plan for PM-10

for the Maricopa County Nonattainment Area

Arizona Revised

Statutes (A.R.S.) Description 

Effective

Dates

A.R.S. § 9-500.04.

Only A.3., A.5.,

A.6., A.7., A.8., A.9.

and H. 

Air quality control; definitions [city and town requirements

in Area A regarding targeting unpaved roads and

shoulders; leaf blower restrictions; restrictions related to

parking, maneuvering, ingress and egress areas and

vacant lots; requirement for certified street sweepers]

9/19/07

A.R.S. § 9-500.27. Off-road vehicle ordinance; applicability; violation;

classification

9/19/07

A.R.S. § 11-871.

Only A., B. and D.4.

Emissions control; no burn; exemptions; penalty [no burn

restriction for any HPA day, increased civil penalty]

9/19/07

A.R.S. § 11-877. Air quality control measures [county leaf blower

restrictions]

9/19/07

A.R.S. § 28-1098.

Only A. and C.1.

Vehicle loads; restrictions; civil penalties [for safety or air

pollution prevention purpose]

9/19/07

A.R.S. § 49-424.

Only 11.

Duties of department [develop and disseminate air quality

dust forecasts for the Maricopa County PM-10

nonattainment area]

7/20/11

A.R.S. § 49-457.01. Leaf blower use restrictions and training; leaf blower

equipment sellers; informational material; outreach;

applicability

9/19/07

A.R.S. § 49-457.03. Off-road vehicles; pollution advisory days; applicability;

penalties

9/19/07

A.R.S. § 49-457.04. Off-highway vehicle and all-terrain vehicle dealers;

informational material; outreach; applicability

9/19/07

A.R.S. § 49-457.05.

Only A., B., C., D.

and I.

Dust action general permit; best management practices;

applicability; definitions

7/20/11

A.R.S. § 49-474.01.

Only A.4., A.5.,

A.6., A.7., A.8.,

A.11., B. and H.

Additional board duties in vehicle emissions control areas;

definitions [county requirements for stabilization of

targeted unpaved roads, alleys and shoulders; restrictions

related to parking, maneuvering, ingress and egress areas

and vacant lots; requirement for certified street sweepers] 

9/19/07

A.R.S. § 49-474.05. Dust control; training; site coordinators 9/19/07

A.R.S. § 49-474.06. Dust control; subcontractor registration; fee 9/19/07

A.R.S. § 49-501.

Only A.2., B.1., C.,

F. and G. 

Unlawful open burning; exceptions; civil penalty; definitions

[ban on outdoor fires from May 1 to September 30;

deletion of recreational purpose exemption; no burn day

restrictions; penalty provision]

9/19/07

A.R.S. § 49-541.

Only 1.

Definitions [Area A] 8/9/01

4 - 2
Table 4-1 Continued

Maricopa County

Air Quality

Department Rules Description

Effective

Dates

310 Fugitive Dust from Dust-Generating Operations

Adopted 1/27/10 and submitted to EPA 4/12/10 [Notice of

Final Rulemaking 75 FR 78167; 12/15/10]

EPA approved

effective

1/14/11

310.01 Fugitive Dust From Non-Traditional Sources of Fugitive

Dust

Adopted 1/27/10 and submitted to EPA 4/12/10 [Notice of

Final Rulemaking 75 FR 78167; 12/15/10]

EPA approved

effective

1/14/11

314 Open Outdoor Fires and Indoor Fireplaces at Commercial

and Institutional Establishments

Adopted 3/12/08 and submitted to EPA 7/10/08 [Notice of

Final Rulemaking 74 FR 57612; 11/9/09]

EPA approved

effective

1/8/10

316 Nonmetallic Mineral Processing

Adopted 3/12/08 and submitted to EPA 7/10/08 [Notice of

Final Rulemaking 74 FR 58553; 11/13/09] 

EPA approved

effective

1/8/10 

Appendix C Fugitive Dust Test Methods

Adopted 3/26/08 and submitted to EPA 7/10/08 [Notice of

Final Rulemaking 75 FR 78167; 12/15/10]

EPA approved

effective

1/14/11

Maricopa County

Ordinance Description

Effective

Dates

P-26 Residential Woodburning Restriction

Adopted 3/26/08 and submitted to EPA 7/10/08; [Notice

of Final Rulemaking 74 FR 57612; 11/9/09]

EPA approved

effective

1/8/10

Appendices Description

Effective

Dates

Appendix C,

Exhibit 1

Arizona Revised Statutes Listed in Table 4-1

Appendix C,

Exhibit 2

Maricopa County Resolution to Evaluate Measures in the

MAG 2012 Five Percent Plan for PM-10 for the Maricopa

County Nonattainment Area

11/16/11

Appendix C,

Exhibit 3

Arizona Department of Environmental Quality Dust Action

General Permit

12/30/11

Appendix C,

Exhibit 4

Arizona Department of Environmental Quality Commitment

to Revise the MAG 2012 Five Percent Plan for PM-10 for

the Maricopa County Nonattainment Area if Necessary for

the Emerging and Voluntary Measure

4 - 3
Maricopa County Rule 316 (Nonmetallic Mineral Processing) regulates fugitive dust and

process dust emissions from sources and activities such as: mining, excavating,

separating, combining, crushing and grinding any nonmetallic mineral, asphaltic concrete

plants, raw material storage and distribution, concrete plants, bagging operations, open

storage piles, material handling, haul roads, and trackout onto paved surfaces from these

sources.

MARICOPA COUNTY RESOLUTION TO EVALUATE MEASURES IN THE MAG 2012

FIVE PERCENT PLAN FOR PM-10 FOR THE MARICOPA COUNTY NONATTAINMENT

AREA

Maricopa County indicates that the Maricopa Board of Supervisors adopted a resolution

on November 16, 2011 that included a commitment for the Evaluation of New Innovative

Control Measures and Existing Maricopa County Control Measures. Maricopa County

indicates that the Maricopa County Air Quality Department will develop and assess the

effectiveness of the innovative control program implemented through the dust generation

forecast and Dust Action General Permit on permitted and unpermitted sources of PM-10

in Maricopa County on forecast high risk days. Maricopa County will perform a rule

effectiveness study on the implementation of existing dust control rules.

The Maricopa County Board of Supervisors is authorized by A.R.S. § 49-479 to adopt rules

for air pollution control and by A.R.S. § 49-480 to establish, administer and enforce a

program for air quality permits. The Board adopted rules establishing an air quality permit

program and pursuant to A.R.S. § 49-473, designated the Air Quality Department to issue

permits and administer and enforce the permit program. In the Memorandum of Agreement

developed in 1992 under A.R.S. § 49-406(F), Maricopa County is responsible for tracking

emissions from point, area and non-road mobile sources and for tracking the

implementation of control measures. By operation of A.R.S. § 49-471, the executive head

of the department designated under A.R.S. § 49-473 serves as the Air Pollution Control

Officer. The Air Pollution Control Officer is specifically authorized to take the enforcement

actions set forth in A.R.S. §§ 49-502, 49-511, 49-512 and 49-513. A.R.S. § 474.01(A)(11)

requires adoption of rule provisions by March 31, 2008, and enforcement of the provisions

by October 1, 2008, regarding stabilization of disturbed surfaces of vacant lots. 

Implementation Schedule:

The Air Quality Department in consultation with the U. S. Environmental Protection Agency

completed a rule effectiveness study analyzing the impact of Rules 310, 310.01 and 316

for the 2008 PM-10 Periodic Emissions Inventory contained in Appendix A, Exhibit 1 of the

MAG 2012 Five Percent Plan for PM-10 for the Maricopa County Nonattainment Area. The

department in consultation with EPA will use a similar approach and process with an

appropriate temporal period to evaluate the new innovative control measures such as the

dust generation forecast and Dust Action General Permit. The Air Quality Department will

conduct the program evaluations as follows: 

4 - 4
Initial Evaluation:

January 2013 Initiate evaluation process for new innovative control measures and

existing rule effectiveness studies.

March 2013 Complete draft program evaluation reports.

April 2013 Complete final program evaluation reports.

Periodic Evaluation: The department will reevaluate the effectiveness of the new innovative

control measures as part of the periodic emissions inventory required by EPA every three

years.

Program evaluations will be accommodated as part of the air quality compliance,

enforcement and planning processes and will be coordinated by the Maricopa County Air

Quality Department’s existing Planning and Analysis Division.

The Maricopa County Air Quality Department administers the air quality program in

Maricopa County. Currently the department has 140.6 employees. The Maricopa County

Air Quality Department's FY 2010-11 revenue was approximately $15.3 million. No change

in funding is anticipated for these program evaluations.

The Air Quality Department's enforcement options for regulatory programs include orders

of abatement, civil actions for injunctive relief or civil penalties, and filing a class 1

misdemeanor citation. Senate Bill 1552 authorizes the county to enter the lot to stabilize

the disturbed surface, issue notices of violation, and collect monetary penalties that include

the cost of stabilization.

As noted above, the Air Quality Department will assess and evaluate the effectiveness of

the new innovative measures as well as the complete rule effectiveness studies for the

existing Rules 310, 310.01 and 316 (see Appendix C, Exhibit 2).

ARIZONA DEPARTMENT OF ENVIRONMENTAL QUALITY DUST ACTION GENERAL

PERMIT

The Arizona Department of Environmental Quality indicates that since the start of Calendar

Year 2008, the majority of exceedances of the PM-10 National Ambient Air Quality

Standard (NAAQS) in the Maricopa County Serious PM-10 Nonattainment Area have been

related to high wind events. High wind events, along with a number of other meteorological

conditions that can lead to the generation of dust can be predicted through meteorological

forecasts.

In accordance with A.R.S. § 49-424(11), ADEQ is developing and disseminating an air

quality dust forecast for the Maricopa County Serious PM-10 Nonattainment Area. Based

upon knowledge of historical and recent meteorological conditions, and the prediction of

4 - 5
such factors as wind speed and wind direction, forecasts identify the potential risk of dust

entrainment as “Low”, “Moderate” or “High” for the next five consecutive days. ADEQ

updates this five-day Maricopa County Dust Control Forecast every Sunday through Friday,

and posts it on its website at http://www.azdeq.gov/environ/air/ozone/mcdust.pdf. 

In accordance with A.R.S. § 49-457.05, this Dust Action General Permit identifies a series

of Best Management Practices (BMPs) for specific dust generating operations. When

ADEQ’s Maricopa County Dust Control Forecast predicts that a day is at high risk for dust

generation, those dust generating operations that are not already required to control dust

through a permit issued by the Arizona Department of Environmental Quality (ADEQ) or

the Maricopa County Air Quality Department (MCAQD) are expected to choose and

implement at least one BMP to reduce or prevent PM-10 emissions. Implementation of a

BMP is expected to occur as soon as practicable before and during the high risk event. 

Although the BMPs in the Dust Action General Permit only apply to those sources that do

not already have a permit, even dust generating operations with an air quality permit are

also expected to implement the dust controls in their permit at the same time.

According to state statute, BMPs identified in the Dust Action General Permit are expected

to be employed absent the requirement to obtain an air quality permit. If the owner or

operator of a dust-generating operation is found by ADEQ’s Director to have failed to

choose and implement an applicable BMP as soon as practicable before and during a day

that is forecast to be at high risk of dust generation, then the owner or operator can be

required to obtain an Authorization to Operate under the Dust Action General Permit. The

process by which ADEQ’s Director makes such a finding is identified within the Dust Action

General Permit. Violations of the Dust Action General Permit are subject to the

enforcement requirements of Arizona Revised Statutes Title 49, Chapter 3, Article 2,

including civil penalties of up to ten thousand dollars per day, per violation, pursuant to

Section 463.

In accordance with A.R.S. § 49-457.05(E) this Dust Action General Permit was subject to

a 30-day public comment period and shall be effective for a period of five-years (see

Appendix C, Exhibit 3).

ARIZONA DEPARTMENT OF ENVIRONMENTAL QUALITY COMMITMENT TO REVISE

THE MAG 2012 FIVE PERCENT PLAN FOR PM-10 FOR THE MARICOPA COUNTY

NONATTAINMENT AREA IF NECESSARY FOR THE EMERGING AND VOLUNTARY

MEASURE

The Arizona Department of Environmental Quality indicates that A.R.S. § 49-404 requires

ADEQ to maintain a State Implementation Plan that provides for the implementation,

maintenance and enforcement of national ambient air quality standards. Should it be

demonstrated through Maricopa County's April 2013 final program evaluation reports that

the emerging and voluntary measure contained within the Five Percent Plan did not

achieve the necessary emissions reductions, the Arizona Department of Environmental

Quality commits to submitting a SIP revision that contains replacement measures to reduce

4 - 6
PM-10 emissions by an amount equal to or more than the total PM-10 emissions reductions

that were not achieved by these measures. An implementation schedule for the submission

of this revised plan is as follows:

May 2013 ADEQ will consult with MAG to determine if additional emissions

reductions are necessary.

June 2013 If additional controls are required, ADEQ will work with MAG to

identify potential replacement measures.

April 2014 If additional controls are required, ADEQ will submit a SIP revision

that contains the necessary replacement measure(s).

ADEQ does not anticipate the need for additional personnel or funding to comply with this

commitment as any required SIP revisions will be accommodated as part of its normal air

quality planning process (see Appendix C, Exhibit 4).

CONTINGENCY REQUIREMENT

The 2012 Five Percent Plan also includes contingency measures that were implemented

early such as PM-10 certified street sweeping on freeways and arterials, as well as the

projects completed in 2008-2011 that paved and stabilized unpaved roads, alleys and

shoulders; reduced speed limits; and overlaid highways with rubberized asphalt. These

PM-10 reduction projects were implemented in the PM-10 nonattainment area by twentyone cities and towns, Maricopa County, Pinal County, Arizona Department of

Transportation and the Gila River Indian Community. All of the projects for which credit

was taken were open to traffic by September 2011. EPA encourages early implementation

of contingency measures to reduce emissions as expeditiously as practicable. The

contingency measures and projects are described in Chapter 6.

ASSURANCES THAT THE STATE HAS THE AUTHORITY TO IMPLEMENT THE

MEASURES IN THE PLAN

In order to comply with Section 110(a)(2)(E) of the Clean Air Act, a State law was passed

in 1992 which provides an approach for assurances that State and local measures will be

adequately implemented (A.R.S. § 49-406 I. and J.). If any person (includes State, County,

local governments, regional agencies, and other entities) fails to implement a measure as

described in the resolution adopted pursuant to A.R.S. § 49-406 G., the County would file

an action in Superior Court to have the Court order that the measure be implemented. 

Likewise, the Director of the Arizona Department of Environmental Quality will backstop the

County if it fails to implement a measure or if the County fails to backstop the local

governments and regional agencies.

Regarding measures, A.R.S. § 49-406 G. (passed by the Legislature in 1992) requires that

each agency which commits to implement any control measure contained in the State

4 - 7
Implementation Plan must describe the commitment in a resolution. The resolution must

be adopted by the appropriate governing body of the agency. State law also requires the

entity to specify the following information in the resolutions: (1) its authority for

implementing the limitation or measure as provided in statute, ordinance, or rule; (2) a

program for the enforcement of the limitation or measure; and (3) the level of personnel and

funding allocated to the implementation of the measure.

As noted in the MAG regional air quality plans, the action taken by the MAG Regional

Council to approve the Suggested Measures and Adopted Plan Measures does not commit

each jurisdiction to implement those measures. As indicated in the resolutions and

commitments, each jurisdiction determines which measures are reasonably available for

implementation by that jurisdiction.

TRACKING PLAN IMPLEMENTATION

The Maricopa County Air Quality Department determines reasonable further progress and

reviews the implementation status of the various measures contained in the air quality

plans. The Maricopa County Air Quality Department will also continue to have the

responsibility for conducting ambient air quality monitoring.

Supplemental to these tracking efforts, the Maricopa Association of Governments publishes

regional traffic flow maps and calculates regional vehicle miles of travel from these flow

maps. MAG also conducts vehicle occupancy studies and performs special traffic volume

and speed studies, as needed. Phoenix Public Transit continuously monitors transit

ridership for each month. The Regional Public Transportation Authority will also be

collecting transit and carpooling ridership information. The Arizona Department of

Environmental Quality continuously monitors the number of vehicles inspected in the

Vehicle Emissions Inspection Maintenance Program, the number of vehicles failing the test,

and the improvement in tail pipe emissions after failed vehicles are repaired.

In addition, the MAG Air Quality Technical Advisory Committee will review the information

pertaining to the implementation of measures. The committee will also review the air

quality monitoring data to assist in tracking air quality improvement over time.

4 - 8
CHAPTER FIVE

DEMONSTRATION OF ANNUAL FIVE PERCENT REDUCTIONS IN 

PM-10 EMISSIONS

Chapter Five demonstrates that the MAG 2012 Five Percent Plan for PM-10 meets the

Clean Air Act requirement that PM-10 emissions be reduced by five percent per year until

attainment is demonstrated. Section 189(d) of the Clean Air Act requires that the Five

Percent Plan provide for an annual reduction in PM-10 emissions of not less than five

percent of the total emissions in the most recent inventory prepared for the area. 

This chapter describes the increases in rule effectiveness that achieve annual reductions

of at least five percent of the emissions inventory for 2007, the base year for the plan. The

2007 emissions inventory is based on the revised 2008 PM-10 Periodic Emission Inventory

for the Maricopa County, Arizona, Nonattainment Area (PEI), which is the most recent

inventory prepared for the area (Appendix A, Exhibit 1). Since the attainment date for this

Plan is December 31, 2012, annual five percent reductions are required for five years, 2008

through 2012. As discussed in detail in Chapter Six, attainment can not be achieved prior

to December 31, 2012, because there have been several exceedances of the 24-hour PM10 standard in 2009 and 2011 which may be due to exceptional events and the required

documentation for these events has not yet been submitted to EPA for concurrence. 

Additionally, modeled attainment cannot be achieved without the credit achieved through

the new Dust Action General Permit measure (described below) which is not fully

implemented until January 1, 2012. 

MEASURES QUANTIFIED TO MEET THE FIVE PERCENT REDUCTION REQUIREMENT

Fifty-three control measures were submitted to EPA in December 2007 as part of the MAG

2007 Five Percent Plan for PM-10. The 2007 Plan was withdrawn by the Arizona

Department of Environmental Quality in January 2011. Most of the measures in the 2007

Plan were implemented during the three years before the Plan was withdrawn. The

measures submitted in the MAG 2012 Five Percent Plan for approval into the Arizona State

Implementation Plan are listed in Table 4-1. Many of the measures from the 2007 Plan

have been included in Table 4-1. 

To meet the annual five percent reduction requirement in Section 189(d) of the Clean Air

Act, the MAG 2012 Five Percent Plan takes credit for increases in rule effectiveness for

Maricopa County Rules 310 (Fugitive Dust from Dust-Generating Operations), 310.01

(Fugitive Dust from Non-Traditional Sources of Fugitive Dust) and 316 (Nonmetallic Mineral

Processing). The increases in rule effectiveness are attributable to strengthened

enforcement and increased compliance with these rules. EPA has approved Rules 310

and 310.01 (EPA, 2010) and Rule 316 (EPA, 2009), as part of the State Implementation

Plan. Compliance with these rules has increased every year since 2007, as shown in Table

5-1. 

5 - 1
These Maricopa County rules reduce emissions from a wide variety of sources and apply

to the Maricopa County area. Maricopa County Rule 310 (Fugitive Dust from DustGenerating Operations) regulates fugitive dust emissions from sources and activities such

as: land clearing, earthmoving, weed abatement, excavating, construction, demolition, bulk

material handling, storage and transporting operations, outdoor equipment, motorized

machinery, staging areas, parking areas, material storage areas, haul roads, disturbed

surface areas, initial landscapes and trackout onto paved surfaces from these sources.

Maricopa County Rule 310.01 (Fugitive Dust from Non-Traditional Sources of Fugitive

Dust) regulates fugitive dust emissions from sources and activities such as: vehicle use in

open areas and vacant lots, open areas, vacant lots, unpaved parking lots, unpaved

roadways (including alleyways), easements, rights-of-way, access roads and trackout onto

paved surfaces from these activities.

Maricopa County Rule 316 (Nonmetallic Mineral Processing) regulates fugitive dust and

process dust emissions from sources and activities such as: mining, excavating,

separating, combining, crushing and grinding any nonmetallic mineral, asphaltic concrete

plants, raw material storage and distribution, concrete plants, bagging operations, open

storage piles, material handling, haul roads, and trackout onto paved surfaces from these

sources.

Emission reduction credit is also taken for one new measure, the Dust Action General

Permit, which will be fully implemented by January 1, 2012, as discussed in Chapter Four. 

Credit for this measure is allowed under the EPA guidance, Incorporating Emerging and

Voluntary Measures in a State Implementation Plan (EPA, 2004). The measures used to

demonstrate the annual five percent reductions are also used in modeling for the

attainment demonstration, as described in Chapter Six.

In addition to demonstrating five percent reductions and modeling attainment, this Plan

must meet contingency requirements of the Clean Air Act. It is important to note that the

contingency requirements must be satisfied by quantifying the benefit of different measures

than those used to meet the five percent and attainment demonstration requirements. The

contingency requirements met by this Plan are also discussed in Chapter Six.

Strengthened enforcement and increased compliance with Maricopa County Rules 310,

310.01 and 316 have raised compliance rates significantly since 2007. The benefits of

increased compliance with these rules have been quantified to show the annual five

percent reductions in PM-10 emissions. The rule effectiveness (RE) rates have been

calculated for 2007 through 2010, using actual inspection data and a methodology

developed by the Maricopa County Air Quality Department (MCAQD), in consultation with

EPA. 

Table 5-1 shows the rule effectiveness rates calculated for 2007 through 2010. The RE 

5 - 2
Table 5-1

Impact of Increased Rule Effectiveness on 2008-2012 PM-10 Emissions

Categories Affected by Rule Effectiveness

Base Case Emissions (tons/year) Ru

2007 2008 2009 2010 2011 2012 2007 20

Residential Construction 3,423 2,815 1,939 1,656 1,602 1,627 76% Commercial Construction 8,205 6,748 4,649 3,971 3,839 3,901 76% Road Construction 4,150 3,412 2,351 2,008 1,942 1,973 76% All Other Earthmoving 328 270 186 159 154 156 76% Non-metallic mineral mining 306 290 257 246 247 260 40% Mining & Quarrying 256 242 214 205 206 217 40% Industrial paved/unpaved road travel 771 728 645 618 621 654 40% Windblown Agriculture 448 448 448 448 448 448 n/a Windblown Construction 566 566 566 566 566 566 76% Windblown Vacant, Open, Landfill, Test Tracks 5,430 5,430 5,430 5,430 5,430 5,430 85% 

Windblown Sand & Gravel, Mining 190 190 190 190 190 190 40% TOTALS: 24,073 21,139 16,876 15,497 15,244 15,422

Categories Affected by Rule Effectivenss

Controlled Emissions (tons/year) Benefits 

2007 2008 2009 2010 2011 2012 2008 20

Residential Construction 3,423 1,692 1,056 807 780 793 1,122 Commercial Construction 8,205 4,057 2,531 1,935 1,871 1,901 2,691 2Road Construction 4,150 2,052 1,280 979 946 961 1,361 1All Other Earthmoving 328 162 101 77 75 76 108 Non-metallic mineral mining 306 188 152 132 132 139 102 Mining & Quarrying 256 157 127 110 110 116 85 Industrial paved/unpaved road travel 771 472 382 331 333 351 256 Windblown Agriculture 448 448 448 448 448 448 0 Windblown Construction 566 391 366 341 341 341 175 Windblown Vacant, Open, Landfill, Test Tracks 5,430 3,938 3,788 3,788 3,788 3,639 1,492 1Windblown Sand & Gravel, Mining 190 132 123 113 113 113 58 TOTALS: 24,073 13,689 10,353 9,062 8,939 8,879 7,450 6Note: The increase of 1% for the 2012 higlighted rule effectiveness rate for windblown vacant and open lands is the result oGeneral Permit Measure.

5 - 3
rates have been applied to the base case emissions for the source categories shown in

Table 5-1 to quantify the PM-10 emission reductions attributable to strengthened

enforcement and increased compliance with Rules 310, 310.01 and 316. The RE rate

increases are held constant after 2010. 

As mentioned earlier, the five percent reductions also include the benefits of one new

measure, the Dust Action General Permit, which was passed by the Arizona Legislature in

April 2011. This new measure is expected to raise rule effectiveness for Rule 310.01 by

one percent during high wind hours, resulting in the RE rate highlighted in Table 5-1 for

windblown vacant land, open space, landfills and test tracks in 2012. Additional details

regarding the calculation of the PM-10 emissions reduction associated with the increases

in rule effectiveness are provided in the TSD (Chapter III of Appendix B, Exhibit 1).

EPA allows an emission reduction benefit to be taken for the new Dust Action General

Permit, as an emerging measure (EPA, 2004). According to EPA guidance, emerging

measures do not have the same high level of certainty as traditional measures for

quantification purposes in a State Implementation Plan (SIP). The PM-10 emission

reduction increment necessary to demonstrate attainment in 2012 (i.e., total 2012 base case

emissions (in Table 5-2) minus total 2012 emissions with increased rule effectiveness (in

Table 5-3), is 6,543 tons. EPA allows emerging and voluntary measures to account for 

up to six percent of this increment (in this case, a maximum of 393 tons). The one percent

increase in RE during high wind hours will reduce PM-10 emissions by 149 tons in 2012. 

Since this reduction is less than 393 tons, benefit for this new measure may be used in

meeting the annual five percent reduction requirement and demonstrating attainment in this

Plan.

As required by EPA's emerging and voluntary measure guidance, Maricopa County has

made a commitment to retrospectively assess the performance of the Dust Action General

Permit. MCAQD will evaluate the effectiveness of Rules 310, 310.01 and 316 to ensure that

this measure achieves at least a 149 ton reduction during calendar year 2012. The County's

commitment and the method to be used in calculating rule effectiveness are described in

Chapter Four and Appendix C, Exhibit 2. 

DEMONSTRATION FOR THE FIVE PERCENT REDUCTION REQUIREMENT

As discussed above, increases in Rule Effectiveness (RE) for Rules 310, 310.01 and 316

have been quantified to meet the annual five percent reductions required in Section 189(d)

of the Clean Air Act. Table 5-2 provides the base case emissions used to calculate the

annual five percent reductions. The 2008 emissions in this table are based on the most

recent version of the 2008 PEI, published in June 2011 (Appendix A, Exhibit 1). 

The 2007 and 2009-2012 base case emissions were derived from the 2008 PEI emissions,

using annual population and employment growth factors published in August 2011 by

Marshall Vest of the Economic and Business Research Center at the University of Arizona.

These projections are based on the 2010 U.S. Census and the latest economic forecasts 

5 - 4
Table 5-2

2007-2012 Base Case PM-10 Emissions in the PM-10 Nonattainment Area

Source Category

2007 2008 2009 2010 2011 2012

(tons/year)

POINT 159 150 133 127 128 135

AREA

Fuel combustion 1,276 1,301 1,307 1,311 1,316 1,328

Commercial cooking 974 993 998 1,001 1,005 1,014

Construction (includes windblown dust) 16,672 13,811 9,692 8,359 8,102 8,223

Tilling, harvesting and cotton ginning 936 893 893 893 893 893

Travel on unpaved farm roads 769 731 731 731 731 731

Livestock 261 261 261 261 261 261

Travel on unpaved parking lots 2,376 2,422 2,434 2,441 2,451 2,473

Offroad recreational vehicles 2,139 2,180 2,191 2,198 2,206 2,226

Leaf blowers 878 895 899 902 906 914

Windblown agriculture 448 448 448 448 448 448

Other windblown sources 5,430 5,430 5,430 5,430 5,430 5,430

Fires 497 497 497 497 497 497

Mining/quarrying (includes windblown

dust) 752 721 661 641 643 667

Travel on industrial paved/unpaved roads 771 728 645 618 621 654

Other industrial sources 1,033 976 865 828 832 877

NONROAD

Aircraft 194 184 152 142 143 146

Airport ground support equipment 29 27 23 21 20 20

Locomotives 34 34 34 34 34 34

Other nonroad equipment 1,710 1,683 1,661 1,641 1,595 1,513

ONROAD

Exhaust 2,943 2,836 2,647 2,371 1,843 1,407

Tire wear 246 256 257 257 258 261

Brake wear 728 758 767 771 773 787

Paved roads 7,749 8,155 8,214 8,289 8,323 8,422

Unpaved roads and alleys 10,218 10,312 10,284 10,284 10,284 10,312

Totals 59,218 56,681 52,123 50,497 49,743 49,673

5 - 5
for the Phoenix-Mesa metropolitan area. Since the economic outlook for Arizona remains

extremely unstable, the actual population and employment levels in 2011 and 2012 may

differ somewhat from the projections. However, the University of Arizona growth factors

represent the most reliable data currently available. Details regarding the population and

employment projections and other technical assumptions used in generating the base case

emissions are provided in the TSD (Chapter II of Appendix B, Exhibit 1). 

The annual five percent reduction target was calculated by multiplying the total 2007 PM-10

emissions in Table 5-2 (59,218 tons) by five percent, which results in 2,961 tons. To meet

the 189(d) requirement, the 2008 emissions with increased rule effectiveness must be at

least 2,961 tons less than the 2007 base case emissions. Each year after 2008 imposes

yet another 2,961 ton reduction requirement. Thus, the cumulative reduction requirements

(relative to 2007 base case emissions) are at least 5,922 tons in 2009, 8,883 tons in 2010,

11,844 tons in 2011, and 14,805 tons in 2012. 

Table 5-3 shows the impact of the increases in rule effectiveness on PM-10 emissions in

2008 through 2012. This table also quantifies the annual five percent reductions for 2008

through 2012. The total reduction in PM-10 emissions between 2007 and 2012 with the

increases in rule effectiveness is 16,089 tons, which represents a 27.2 percent reduction in

total 2007 base case emissions.

Table 5-4 confirms that the annual five percent reduction requirements are met in 2008-

2012 and there is a surplus margin of benefit in each year. The total surplus in 2012 is

1,284 tons. This surplus is needed to model attainment at all monitors in the PM-10

nonattainment area by December 31, 2012. The modeling attainment demonstration is

discussed in Chapter Six.

5 - 6
Table 5-3

2008-2012 PM-10 Emissions with Increased Rule Effectiveness

Source Category

2008 2009 2010 2011 2012

(tons/year)

POINT 150 133 127 128 135

AREA

Fuel combustion 1,301 1,307 1,311 1,316 1,328

Commercial cooking 993 998 1,001 1,005 1,014

Construction (includes windblown dust) 8,355 5,333 4,139 4,014 4,073

Tilling, harvesting and cotton ginning 893 893 893 893 893

Travel on unpaved farm roads 731 731 731 731 731

Livestock 261 261 261 261 261

Travel on unpaved parking lots 2,422 2,434 2,441 2,451 2,473

Offroad recreational vehicles 2,180 2,191 2,198 2,206 2,226

Leaf blowers 895 899 902 906 914

Windblown agriculture 448 448 448 448 448

Other windblown sources 3,938 3,788 3,788 3,788 3,639

Fires 497 497 497 497 497

Mining/quarrying (includes windblown dust) 476 401 355 356 369

Travel on industrial paved/unpaved roads 472 382 331 333 351

Other industrial sources 976 865 828 832 877

NONROAD

Aircraft 184 152 142 143 146

Airport ground support equipment 27 23 21 20 20

Locomotives 34 34 34 34 34

Other nonroad equipment 1,683 1,661 1,641 1,595 1,513

ONROAD

Exhaust 2,836 2,647 2,371 1,843 1,407

Tire wear 256 257 257 258 261

Brake wear 758 767 771 773 787

Paved roads 8,155 8,214 8,289 8,323 8,422

Unpaved roads and alleys 10,312 10,284 10,284 10,284 10,312

Totals 49,231 45,600 44,062 43,438 43,130

5% Reduction Targets (tons/year) 2,961 5,922 8,883 11,844 14,805

Actual Plan Reductions (tons/year) 9,987 13,618 15,157 15,781 16,089

5 - 7
Table 5-4

PM-10 Emission Reductions and Five Percent Reduction Requirements

Year

5% Reduction

Requirement

Total PM-10 Emission

Reductions due to Increases

in Rule Effectiveness

Excess Benefit = Total PM-10

Emission Reductions minus 5%

Reduction Requirement

(tons/year) (tons/year) (tons/year) (%)

2008 2,961 9,987 7,026 237%

2009 5,922 13,618 7,696 130%

2010 8,883 15,157 6,274 71%

2011 11,844 15,781 3,937 33%

2012 14,805 16,089 1,284 9%

5 - 8
REFERENCES

EPA, 2004. Incorporating Emerging and Voluntary Measures in a State Implementation

Plan. Prepared by the EPA Office of Air Quality Standards. September 2004.

EPA, 2009. Revisions to the Arizona State PM-10 Implementation Plan, Maricopa County

Air Quality Department. Final Rule. Federal Register, Volume 74, Number 218, Pages

58553-58554. November 13, 2009.

EPA, 2010. Revisions to the State Implementation Plan, Maricopa County, Arizona. Final

Rule. Federal Register, Volume 75, Number 240, Pages 78167-78168. December 15,

2010.

5 - 9
CHAPTER SIX

ATTAINMENT DEMONSTRATION

Chapter Six describes the modeling that was performed to demonstrate that attainment of

the 24-hour PM-10 standard will be achieved in 2012. The modeling was conducted to

show attainment under high wind conditions since violations of the standard under stagnant

conditions have not occurred since 2006 (see Chapter 3 for monitoring data information).

A modeling attainment demonstration was performed for a 36 square mile area in the Salt

River area, which includes the West 43rd Avenue monitor that has recorded the most

exceedances of the PM-10 standard under high wind conditions during 2005-2010. A

regional attainment demonstration for the entirety of the nonattainment area is also

provided in this chapter. Both the modeling demonstration in the Salt River area and the

entire nonattainment area are based upon a distance-weighted rollback approach.

Windblown PM-10 emission estimates during high wind hours are calculated from back

trajectories while low wind hour emission estimates are derived from land use distribution

within each modeling domain. The benefits of the control measures described in Chapter

Five provide the reductions necessary to model attainment. 

In addition to the modeling attainment demonstrations, this chapter addresses other

requirements of a nonattainment area plan, including reasonable further progress,

contingency measures, and the onroad motor vehicle emissions budget for conformity. The

chapter concludes with a discussion of the control measures in the Five Percent Plan that

will reduce PM-10 emissions sufficiently to achieve attainment as expeditiously as

practicable and the need for an extension of the attainment date deadline to December 31,

2012. 

 

SALT RIVER AREA MODELING

This section describes the modeling and results for the attainment demonstration in the 

Salt River Area. A detailed discussion of the technical methods and assumptions used to

perform the modeling for the Salt River Area is provided in the TSD (Chapter V of Appendix

B, Exhibit 1).

Design Day Selection

PM-10 monitors in the Maricopa County nonattainment area recorded 17 exceedances of

the 24-hour average PM-10 national ambient air quality standard in 2007 (the last year

before the control measures in this plan were implemented). Exceedances were recorded

at six monitoring sites in the nonattainment area: Coyote Lakes, Central Phoenix, Durango,

Higley, South Phoenix and West 43rd Avenue. The Buckeye monitor also exceeded the

standard on two days in 2007, but this monitor is outside the nonattainment area and

therefore was not modeled in this plan.

6 - 1
Of the 17 exceedances recorded within the nonattainment area in 2007, the West 43rd

Avenue monitor recorded the highest number of exceedances with six. The Higley monitor

was next highest with five. The remaining exceeding monitors in the nonattainment area

recorded two or less exceedances in 2007. All but one of the exceedances in 2007

occurred under high wind conditions. For the purposes of this attainment demonstration,

high wind conditions are defined as days when five-minute or hourly average wind speeds

are greater than 12 miles per hour. This value is identical to the threshold for windblown

dust production as identified in the 2008 PM-10 Periodic Emissions Inventory (Appendix

A, Exhibit 1). Table 6-1 provides a tabulation by monitor of the exceedance days, 24-hour

average concentrations and the general meteorological conditions associated with the

exceedances.

The following primary criteria were applied in selecting the design days for PM-10

modeling:

1. Exceedance days with five-minute or hourly average wind speeds > 12 miles

per hour; and 

2. Exceedance days that are unlikely to be considered as a high wind

exceptional event.

The West 43rd Avenue monitor recorded six exceedances when hourly average winds were

greater than 12 miles per hour in 2007. Four of the six exceedance days were associated

with high winds from a frontal storm system, while the remaining two days were associated

with high winds from monsoon season thunderstorm outflows. Days on which

thunderstorm outflow activity occurs have been excluded as candidate days for modeling,

as these days are almost always flagged as uncontrollable exceptional events. 

Two of the four frontal system exceedances days recorded at the West 43rd Avenue monitor

were days in which only the West 43rd Avenue monitor exceeded the standard (March 27

and May 4). These days suggest that the local sources around the West 43rd Avenue

monitor may have been important contributors to the exceedance value. Of these two

dates, May 4, 2007 was chosen as the design day as wind speeds on March 27th were

significantly higher making it a candidate for an exceptional event demonstration. 

For a demonstration of regional attainment across the nonattainment area, the other

exceedance days in 2007 were evaluated using the same criteria employed to select May

4, 2007 for the Salt River area modeling. All high wind days associated with thunderstorm

outflows were removed for consideration due to their designation as uncontrollable

exceptional events. Of the remaining days with high wind days, two days (April 12 and

June 6) recorded exceedances at multiple monitors, indicating that the high winds had a

more regional effect on PM-10 concentrations. Of the these two dates, June 6, 2007 was

chosen as the design day as April 12, 2007 presented very strong state-wide high winds

indicating this date was also a candidate for an exceptional event demonstration. A more 

6 - 2
Table 6-1

Maricopa County and PM-10 Nonattainment Area 24-Hour Average 

PM-10 Standard Exceedance Dates, Measured Concentrations

 and Associated Meteorological Conditions in 2007

Monitor Date PM-10 Conc.

(μg/m3

)

Meteorological Conditions

Buckeye July 19 195.0 Low Winds

November 15 166.2 Irregular Winds

Coyote Lakes July 19 273.4 Thunderstorm Outflow 

October 21 312.9 Frontal System High Winds

Central Phoenix July 19 267.8 Thunderstorm Outflow

Durango Complex November 15 155.7 Irregular Winds

Higley June 6 181.0 Frontal System High Winds

July 19 199.5 Thunderstorm Outflow

August 16 195.6 Thunderstorm Outflow

August 23 230.4 Thunderstorm Outflow

October 24 174.8 Frontal System High Winds

South Phoenix April 12 171.1 Frontal System High Winds

August 13 159.5 Thunderstorm Outflow

West 43rd

Avenue

March 27 227.9 Frontal System High Winds

April 12 202.7 Frontal System High Winds

May 4 197.3 Frontal System High Winds

June 6 225.7 Frontal System High Winds

July 19 178.0 Thunderstorm Outflow

August 16 215.1 Thunderstorm Outflow

Note: The selected design days are highlighted in bold italics. The Buckeye monitor is located outside the PM10 nonattainment area and is not part of the attainment demonstration. The Coyote Lakes monitor was a

special purpose monitor that no longer operates and has since been replaced by the Zuni Hills monitor in late

2009. As such, the Coyote Lakes monitor is not a good candidate for producing a design day. 

6 - 3
detailed discussion on design day selection is presented in the TSD (Chapter V of

Appendix B, Exhibit 1). 

Plots of hourly wind speed and PM-10 concentration for the high wind design days of May

4, 2007 and June 6, 2007 at the West 43rd Avenue and Higley monitors are shown in Figure

6-1 through 6-3.

Modeling Domain

On a high wind design day, the areal extent impacting monitors is largely a function of wind

speed. As such it is necessary to divide the selected design days into high and low wind

hours. High wind hours are represented by sources located along back trajectories and low

wind hours are represented by sources within a modeling domain surrounding the selected

monitoring site. The basis for distinguishing between high and low wind hours is the 12

mph windblown dust aerodynamic entrainment threshold established in the 2008 PM-10

Periodic Emissions Inventory (Appendix A, Exhibit 1). 

Five-minute average wind speed and direction as measured at the West 43rd Avenue

monitor is employed to construct the back trajectories for each high wind hour. Past

modeling of back trajectories indicate that the lands significantly contributing to elevated

PM-10 concentrations recorded at the monitor lie generally within a mile of either side of

the path of the upwind back trajectories (see Section entitled “Establishing the Boundaries

of a High Wind Domain” in Chapter V of Appendix B, Exhibit 1). 

The modeling domain used during the low wind hours for the West 43rd Avenue monitor is

similar to the area initially defined in the ADEQ TSD for the 2005 PM-10 attainment plan

and is bounded by Van Buren Street to the north, Baseline Road to the south, 59th Avenue

to the west and 7th Street to the east. Due to the diversity and number of PM-10 sources

in the Salt River area, it is considered to be a worst-case representation of sources

throughout the nonattainment area. 

Figure 6-4 shows the low wind domain and the high wind back trajectories on May 4, 2007

as originating from the West 43rd Avenue monitor. The highlighted area surrounding the

back trajectories represent the land use domain used for calculating windblown PM-10

emissions during the high wind hours.

Inventory Development

For the high wind hours, hourly windblown PM-10 emissions are calculated based upon the

land uses that fall within the hourly back trajectory. Emissions from the land uses within

each hourly back trajectory are calculated per the methodology described in the 2008 PM10 Periodic Emissions Inventory. Initially, the land uses within each back trajectory are

evaluated for their potential to emit windblown dust. Some land uses are assumed to have

no windblown dust emissions (office/retail), some are partially emissive

(commercial/industrial) and others are assumed to be 100% emissive (vacant lands). 

6 - 4
Figure 6-1

Summary of the Monitoring Conditions at West 43rd Avenue

on the High Wind Design Day

(May 4, 2007)

6 - 5
Figure 6-2

Summary of the Monitoring Conditions at West 43rd Avenue

on the High Wind Design Day

(June 6, 2007)

6 - 6
Figure 6-3

Summary of the Monitoring Conditions at Higley

on the High Wind Design Day

(June 6, 2007)

6 - 7
Figure 6-4

Salt River Area Low Wind Domain and 

May 4, 2007 Hourly High Wind Back Trajectories

and Associated Domains as Originating from West 43rd Avenue Monitor

6 - 8
Land uses that are conservatively assumed to have 100% of their acreage available for

windblown dust production include: vacant and open lands, sand and gravel/mining

lands, lands under development, landfills and unpaved automotive test tracks. Land

uses where only portions of the acreage is available for windblown dust production

include: agricultural lands, industrial lands, commercial lands and large public lands.

Windblown PM-10 emissions from these land uses are calculated by use of emission

factors based upon wind speed and the disturbance level of each land use. The

disturbance level of each land use is derived from rule effectiveness studies of the

fugitive dust rules that regulate the various land uses. The effectiveness of the rule is

assumed to be an approximate surrogate for the average level of disturbance of each

regulated land use. The details of the calculation of the windblown PM-10 emissions

are provided in the TSD (Chapter V of Appendix B, Exhibit 1).

Since there have been no stagnation violations of the 24-hour PM-10 standard since

2006, detailed low wind design-day specific emission inventories are not needed.

However, emissions reductions achieved as a result of controls in this plan during the

low wind hours of the high wind design days are quantifiable and a necessary part of

the attainment demonstration. In order to account for these emissions reductions,

annual low wind emission inventories for the PM-10 nonattainment area are allocated to

the Salt River area domain based upon land use distribution. This allows for

representation of the low wind emissions, and associated control measure benefits, in

the Salt River area domain without having to create a design day inventory. The details

on how low wind emissions are allocated to the Salt River area domain based upon land

use is included in the TSD (Chapter V of Appendix B, Exhibit 1). 

Distance-Weighted Rollback Modeling

The fundamental assumption underlying any rollback method is that pollutant

concentrations are directly proportional to total emissions over the area of interest. A

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. The reduction factor is calculated based upon the distance

between each source and the impacting monitor.

An investigation of results from a limited-term (2010-mid 2011) saturation monitoring

study conducted in the Salt River area and beyond under high wind conditions

suggested the need to account for distance between emission sources and the

impacted monitor. Further testing of different weighting factors through the analysis of

dispersion model AERMOD confirmed that a 1/d weighting factor proved to be the best

form of weight to use in adjusting PM-10 emissions developed through the back

trajectory domains (See section entitled “Source Weighting” in Chapter V of Appendix B,

Exhibit 1 for more information). Thus, all high wind design day emissions inventories

were weighted to account for a 1/d distance from the modeled monitor.

6 - 9
Distance weighting was not applied to the low wind domain, as the low wind domain

primarily serves to identify the predominant land uses near the monitor and thus the

predominant low wind emissions associated with the land uses. The overall reduction in

low wind emissions gained through the implementation of control measures was applied

as the reduction factor to the low wind hourly concentrations without the need to weight

these reductions by distance.

A detailed explanation of the saturation monitoring study and the AERMOD evaluation

can be found in the TSD (Chapter V of Appendix B, Exhibit 1). 

Background Concentrations

The temporary saturation monitoring study also provided insights into nonanthropogenic levels of PM-10 within the nonattainment area. These background values

were established by comparing monitored readings under high and low wind conditions

at the temporary, rural Arlington School monitor and the existing Buckeye monitor

located just outside the western edge of the nonattainment area. The Arlington School

monitor was located approximately 11 miles west of the Buckeye monitor, surrounded

by mostly natural desert land. 

Under high wind conditions (> 12 mph), when the wind is coming primarily from the

west, the Arlington monitor consistently recorded lower PM-10 concentrations than the

Buckeye monitor, which is primarily impacted by PM-10 emissions from agricultural

activities. The median value under high wind conditions at the Arlington monitor was

found to be 21.9 μg/m3

 and is assumed to be the non-anthropogenic background PM-10

concentration for the PM-10 nonattainment area under high wind conditions. A similar

comparison under low wind conditions yielded a median value of 14.9 μg/m3 and is

assumed to be the non-anthropogenic background PM-10 concentration for the PM-10

nonattainment area under low wind conditions. A detailed explanation of the methods

and data used to develop the background values can be found in the TSD (Chapter V of

Appendix B, Exhibit 1).

Control Measure Analysis

To assess the benefits of the control measures under high wind conditions, separate

hourly windblown PM-10 inventories were developed along back trajectory domains

using base case soil disturbance rates in 2007 and then compared against inventories

developed using the predicted soil disturbance rates in 2012. The high wind inventories

are then weighted by distance from the monitor to more accurately represent the

lessening impact of emission sources that are farther away from the modeled monitor. 

The reductions seen during the high wind hours is strictly due to the benefits of control

measures in this plan, as land use is held constant between 2007 and 2012. Table 6-2

provides a summary of the hourly high wind inventories for 2007 and 2012.

6 - 10
Table 6-2

Base Case 2007 and Controlled 2012 High Wind PM-10 Emissions Inventories

for May 4, 2007 Design Day at the West 43rd Avenue Monitor

High Wind

Hour

Un-weighted Emissions

(tons) 

Distance-Weighted

Emissions

(tons/feet from monitor)

% Reduction

of Weighted

Emissions

2007 2012 2007 2012

12 3.05 2.09 2.872E-04 1.900E-04 33.8%

13 9.49 6.36 6.529E-04 4.245E-04 35.0%

14 9.94 6.67 6.866E-04 4.454E-04 35.1%

15 13.94 9.19 8.721E-04 5.581E-04 36.0%

16 13.36 8.81 8.921E-04 5.699E-04 36.1%

17 19.01 12.39 1.190E-03 7.505E-04 36.9%

18 11.84 7.86 7.837E-04 5.033E-04 35.8%

19 6.58 4.44 5.158E-04 3.364E-04 34.8%

21 4.02 2.72 3.236E-04 2.129E-04 34.2%

22 6.63 4.48 5.104E-04 3.330E-04 34.8%

Total 97.86 65.02 6.714E-03 4.324E-03 35.6%

6 - 11
Under low wind conditions, emissions inventories for the Salt River area domain were

developed based upon land use distribution within the Salt River area. Annual 2007

base case and 2012 controlled low wind emissions were each allocated to the land uses

within the domain for comparison of the benefits of the control measures in this plan. 

The reductions seen during the low wind hours are a result of the control measures in

this plan along with adjustments to source categories based upon observed and

expected economic and social growth factors. Table 6-3 provides a summary of the low

wind inventories by land use for 2007 and 2012. Detailed discussions of the creation of

high and low wind inventories is provided in the TSD (Chapter V of Appendix B, Exhibit

1).

Demonstration of Attainment

Assessing the impact of the control measures in this plan on concentrations within the

Salt River area at the West 43rd monitor in 2012 is accomplished through a distanceweighted rollback methodology. As per the methodology, the percent PM-10 emission

reductions recorded between the 2007 and 2012 high and low wind inventories provide

the percent reductions to the hourly concentrations on the design day. Nonanthropogenic background concentrations under high and low wind conditions are held

steady and are not reduced by the benefits seen in the contrast between the 2007 base

and 2012 controlled inventories. The resulting hourly concentrations in 2012 must then

be summed and averaged across the design day in order to compare the 24-Hour value

against the 24-hour PM-10 standard. The 24-hour value must be less the 155 μg/m3

 in

order to demonstrate attainment of the standard.

Table 6-4 provides a summary of the results of the distance-weighted rollback

attainment demonstration for West 43rd Avenue monitor in the Salt River area. A 24-

hour value of 133.2 μg/m3 attests that the control measures in this plan are sufficient to

demonstrate that the West 43rd Avenue monitor will have concentrations below the 24-

hour PM-10 standard in 2012. This indicates that attainment has been demonstrated

under high wind conditions at the West 43rd Avenue monitor within the Salt River area

domain.

6 - 12
Table 6-3

Annual Base Case 2007 and Controlled 2012 Low Wind PM-10 Emissions

Inventories for the Salt River Area Low Wind Domain

Land Use 2007 Emissions

(tons)

2012 Emissions

(tons)

% Reduction

Residential 61.19 62.05 (1.4%)

Commercial 61.34 62.81 (2.4%)

Agriculture 29.19 28.57 2.1%

Vacant/Open 27.97 28.62 (2.3%)

Transportation 167.28 155.42 7.1%

Industrial 465.10 350.77 24.6%

Construction 437.70 132.98 69.6%

Total 1,249.76 821.23 34.3%

6 - 13
Table 6-4

2012 Attainment Demonstration 

High Wind Design Day (May 4, 2007) at the West 43rd Avenue Monitor

Hour Wind

Speed

(mph)

May 4, 2007 PM-10

Concentration

(μg/m3

)

 Background

Concentration

(μg/m3

)

2012 Controlled PM-10

Concentration

(μg/m3

)

0 2.5 25.9 14.9 22.1

1 1.4 19.8 14.9 18.1

2 0.4 27.0 14.9 22.8

3 5.5 31.5 14.9 25.8

4 6.7 50.7 14.9 38.4

5 8.5 82.7 14.9 59.4

6 7.2 117.3 14.9 82.2

7 4.9 71.9 14.9 52.3

8 4.5 73.5 14.9 53.4

9 9.2 73.0 14.9 53.1

10 9.4 144.2 14.9 99.9

11 10.6 147.0 14.9 101.7

12 13.4 196.6 21.9 137.5

13 17.6 521.0 21.9 346.4

14 17.4 451.6 21.9 300.6

15 18.7 449.9 21.9 295.8

16 17.7 311.2 21.9 206.7

17 19.4 570.0 21.9 367.7

18 17.6 357.2 21.9 237.2

19 15.5 204.0 21.9 140.7

20 9.8 174.7 14.9 119.9

21 13.6 148.8 21.9 105.4

22 15.6 281.1 21.9 191.0

23 11.6 205.6 14.9 140.2

24-Hour Avg. 197.3 134.1

Note: High wind hours are highlighted in bold italics.

6 - 14
PM-10 NONATTAINMENT AREA MODELING

Similar to the modeling done for the Salt River area, attainment modeling for the entire

nonattainment area is performed through the use of distance-weighted rollback

modeling. The design day of June 6, 2007 was chosen for the regional attainment

demonstration based upon the criteria discussed earlier in this chapter. A detailed

discussion of the technical methods and assumptions used to perform the modeling for

the nonattainment area is provided in the TSD (Chapter V of Appendix B, Exhibit 1).

Modeling Domain

On the high wind design day of June 6, 2007, both the West 43rd Avenue and the Higley

monitor exceeded the 24-hour PM-10 standard. Five other monitors in the

nonattainment area recorded elevated PM-10 concentrations but did not exceed the

standard; these include: Central Phoenix, Durango Complex, Greenwood, State Super

Site and West Phoenix monitors. Table 6-5 lists the modeled monitors and their 24-

hour average concentrations on June 6, 2007. The other official active PM-10 monitors

in the nonattainment area were all 1-in-6 filter monitors that did not have June 6, 2007

scheduled as a run day and therefore did not monitor 24-hour average PM-10

concentrations. All seven monitors that did record PM-10 concentrations have been

modeled to assure attainment throughout the nonattainment area. 

As was performed for the Salt River area modeling, a 1-mile buffer around each

calculated back trajectory serve as the domain during high wind hours, as developed

from each monitoring location in the nonattainment area. The number of high wind

hours (> 12 mph) varies at each monitoring site depending on the unique physical

characteristics of each site. In fact, the State Super Site which is located in a dense

single-family and multi-family residential area had no high wind hours on June 6, 2007. 

Five-minute wind speed and direction was available to develop back trajectories for the

Durango Complex, Greenwood, West Phoenix and West 43rd Avenue monitors. Hourly

wind speed and direction was used to develop the back trajectories for the Central

Phoenix and Higley monitors. 

The large size of the nonattainment area requires that separate low wind domains

around the modeled monitors be developed to capture the unique mix of land uses

surrounding the monitors. In addition to the Salt River Area domain which includes the

West 43rd Avenue and Durango Complex monitors, a new low wind domain was

developed to represent the land uses around the Higley monitor located in the eastern

portion of the nonattainment area. A third domain, labeled as the Central City domain,

was developed to include central Phoenix monitors of Central Phoenix, Greenwood,

State Super Site and West Phoenix. All four of these monitors are located in areas with

dense residential and mixed retail/commercial/industrial land uses (see Table V-34

through V-36 in Chapter V of Appendix B, Exhibit 1, for distribution of land uses in low

wind domains). Figure 6-5 displays the June 6, 2007 high wind back trajectory domains

and the low wind domains used in the regional attainment modeling.

6 - 15
Table 6-5

24-Hour Average PM-10 Concentrations on the High Wind Design Day

(June 6, 2007)

Monitor 24-Hour PM-10 Concentration (μg/m3)

Central Phoenix 107.0

Durango Complex 133.7

Greenwood 121.7

Higley 181.1

State Super Site 80.6

West Phoenix 108.8

West 43rd Avenue 225.7

6 - 16
Figure 6-5

PM-10 Nonattainment Area Low Wind Domains and 

June 6, 2007 Hourly High Wind Back Trajectories and Associated Domains

Note: Emissions from the portions of back trajectory domains that are outside of the nonattainment area

are not included as part of the attainment modeling.

6 - 17
Demonstration of Attainment

Both the hourly high wind back trajectory and low wind modeling domain inventories are

developed using the same methodology employed in the development of the inventories

for the Salt River area. Base case 2007 and controlled case 2012 inventories are thus

compared to provide the high and low wind reductions to concentrations seen on the

design day. Tables 6-6 through 6-11 provide a summary of the hourly high wind

emission inventories and associated reduction percentages. Tables 6-12 through 6-13

provide a summary of the low wind domain inventories and associated reduction

percentages for the Central City and Higley domains (the Salt River area domain has

already been presented in Table 6-3). 

The assumptions used to develop non-anthropogenic background values and analysis

of control measure benefits in this plan carry over from the modeling demonstration for

the Salt River area. Detailed discussion on all aspects of the regional nonattainment

modeling can be found in the TSD (Chapter V of Appendix B, Exhibit 1).

Tables 6-14 through 6-20 provide a summary of the results of the distance-weighted

rollback attainment demonstration for the seven monitors included in the regional

nonattainment demonstration for the June 6, 2007 design day. All seven monitors have

24-hour average PM-10 values under 155 μg/m3

 which indicates that attainment has

been demonstrated under high wind conditions throughout the PM-10 nonattainment

area.

6 - 18
Table 6-6

Base Case 2007 and Controlled 2012 High Wind PM-10 Emissions Inventories

for June 6, 2007 Design Day at the Central Phoenix Monitor

High Wind

Hour

Un-weighted Emissions

(tons) 

Distance-Weighted

Emissions

(tons/feet from monitor)

% Reduction

of Weighted

Emissions

2007 2012 2007 2012

0 1.90 1.32 7.549E-05 5.230E-05 30.7%

1 0.99 0.74 5.184E-05 3.687E-05 28.9%

6 1.69 1.18 6.873E-05 4.797E-05 30.2%

7 0.99 0.74 5.254E-05 3.730E-05 29.0%

10 0.88 0.64 4.939E-05 3.485E-05 29.4%

11 2.01 1.41 7.319E-05 5.123E-05 30.0%

12 4.01 2.91 1.706E-04 1.166E-04 31.7%

13 7.52 5.04 2.448E-04 1.625E-04 33.6%

14 7.28 4.96 2.265E-04 1.520E-04 32.9%

15 4.33 3.04 1.657E-04 1.121E-04 32.3%

16 4.27 3.13 1.737E-04 1.192E-04 31.4%

17 2.29 1.60 8.494E-05 5.855E-05 31.1%

18 2.21 1.55 7.971E-05 5.545E-05 30.4%

Total 40.39 28.25 1.517E-03 1.037E-03 31.7%

6 - 19
Table 6-7

Base Case 2007 and Controlled 2012 High Wind PM-10 Emissions Inventories

for June 6, 2007 Design Day at the Durango Complex Monitor

High Wind

Hour

Un-weighted Emissions

(tons) 

Distance-Weighted

Emissions

(tons/feet from monitor)

% Reduction

of Weighted

Emissions

2007 2012 2007 2012

11 1.99 1.37 1.340E-04 9.011E-05 32.8%

12 3.69 2.55 2.267E-04 1.543E-04 31.9%

13 3.12 2.15 1.876E-04 1.281E-04 31.7%

14 8.02 5.49 4.672E-04 3.093E-04 33.8%

15 9.84 7.07 4.992E-04 3.379E-04 32.3%

16 5.62 3.79 3.247E-04 2.160E-04 33.5%

17 2.47 1.72 1.619E-04 1.110E-04 31.4%

Total 34.74 24.13 2.001E-03 1.347E-03 32.7%

6 - 20
Table 6-8

Base Case 2007 and Controlled 2012 High Wind PM-10 Emissions Inventories

for June 6, 2007 Design Day at the Greenwood Monitor

High Wind

Hour

Un-weighted Emissions

(tons) 

Distance-Weighted

Emissions

(tons/feet from monitor)

% Reduction

of Weighted

Emissions

2007 2012 2007 2012

12 1.05 0.77 5.872E-05 4.191E-05 28.6%

13 1.03 0.80 6.482E-05 4.701E-05 27.5%

14 3.03 2.16 1.618E-04 1.110E-04 31.4%

15 2.34 1.75 1.266E-04 8.868E-05 30.0%

Total 7.45 5.49 4.119E-04 2.886E-04 29.9%

6 - 21
Table 6-9

Base Case 2007 and Controlled 2012 High Wind PM-10 Emissions Inventories

for June 6, 2007 Design Day at the Higley Monitor

High Wind

Hour

Un-weighted Emissions

(tons) 

Distance-Weighted

Emissions

(tons/feet from monitor)

% Reduction

of Weighted

Emissions

2007 2012 2007 2012

10 0.74 0.55 6.103E-05 4.481E-05 26.6%

11 3.00 2.05 1.944E-04 1.330E-04 31.6%

12 2.15 1.54 1.805E-04 1.270E-04 29.6%

13 2.41 1.69 1.824E-04 1.268E-04 30.4%

14 5.61 3.83 2.282E-04 1.553E-04 31.9%

15 5.70 3.98 2.113E-04 1.442E-04 31.8%

16 5.65 3.90 2.065E-04 1.403E-04 32.1%

17 1.50 1.11 6.687E-05 4.791E-05 28.4%

Total 26.76 18.64 1.331E-03 9.195E-04 30.9%

6 - 22
Table 6-10

Base Case 2007 and Controlled 2012 High Wind PM-10 Emissions Inventories

for June 6, 2007 Design Day at the West Phoenix Monitor

High Wind

Hour

Un-weighted Emissions

(tons) 

Distance-Weighted

Emissions

(tons/feet from monitor)

% Reduction

of Weighted

Emissions

2007 2012 2007 2012

11 0.65 0.53 2.164E-05 1.680E-05 22.4%

12 1.78 1.33 5.329E-05 3.930E-05 26.2%

13 3.35 2.45 8.177E-05 5.933E-05 27.4%

14 4.27 3.08 1.123E-04 8.105E-05 27.8%

15 1.63 1.21 4.623E-05 3.396E-05 26.5%

Total 11.67 8.60 3.152E-04 2.304E-04 26.9%

6 - 23
Table 6-11

Base Case 2007 and Controlled 2012 High Wind PM-10 Emissions Inventories

for June 6, 2007 Design Day at the West 43rd Avenue Monitor

High Wind

Hour

Un-weighted Emissions

(tons) 

Distance-Weighted

Emissions

(tons/feet from monitor)

% Reduction

of Weighted

Emissions

2007 2012 2007 2012

0 2.29 1.59 2.064E-04 1.388E-04 32.8%

5 3.31 2.29 2.894E-04 1.924E-04 33.5%

6 5.05 3.43 4.359E-04 2.860E-04 34.4%

10 3.44 2.38 2.835E-04 1.898E-04 33.1%

11 6.67 4.51 4.937E-04 3.237E-04 34.4%

12 6.02 4.06 5.697E-04 3.704E-04 35.0%

13 5.66 3.82 4.721E-04 3.088E-04 34.6%

14 9.67 6.48 6.830E-04 4.425E-04 35.2%

15 13.99 9.12 9.717E-04 6.168E-04 36.5%

16 9.67 6.48 6.630E-04 4.304E-04 35.1%

17 5.10 3.45 4.285E-04 2.812E-04 34.4%

18 4.94 3.34 3.857E-04 2.526E-04 34.5%

Total 75.81 50.97 5.883E-03 3.833E-03 34.8%

6 - 24
Table 6-12

Annual Base Case 2007 and Controlled 2012 Low Wind PM-10 Emissions

Inventories for the Central City Low Wind Domain

Land Use 2007 Emissions

(tons)

2012 Emissions

(tons)

% Reduction

Residential 118.19 119.87 (1.4%)

Commercial 87.33 89.43 (2.4%)

Agriculture 0.00 0.00 0.0%

Vacant/Open 25.73 26.33 (2.3%)

Transportation 102.23 93.67 7.1%

Industrial 262.58 198.03 24.6%

Construction 164.80 50.07 69.6%

Total 760.86 577.41 24.0%

6 - 25
Table 6-13

Annual Base Case 2007 and Controlled 2012 Low Wind PM-10 Emissions

Inventories for the Higley Low Wind Domain

Land Use 2007 Emissions

(tons)

2012 Emissions

(tons)

% Reduction

Residential 40.97 41.55 (1.4%)

Commercial 15.28 15.65 (2.4%)

Agriculture 46.15 45.17 2.1%

Vacant/Open 16.62 17.01 (2.3%)

Transportation 162.98 149.34 7.1%

Industrial 2.58 1.95 24.6%

Construction 312.06 94.81 69.6%

Total 596.65 365.49 38.5%

6 - 26
Table 6-14

2012 Attainment Demonstration 

High Wind Design Day (June 6, 2007) at the Central Phoenix Monitor

Hour Wind

Speed

(mph)

June 6, 2007 PM-10

Concentration

(μg/m3

)

 Background

Concentration

(μg/m3

)

2012 Controlled PM-10

Concentration

(μg/m3

)

0 12.5 138.5 21.9 102.7

1 13.1 176.2 21.9 131.6

2 8.6 133.6 14.9 105.1

3 8.0 109.7 14.9 86.9

4 10.9 92.9 14.9 74.2

5 10.3 81.5 14.9 65.5

6 12.4 99.6 21.9 76.1

7 12.8 104.0 21.9 80.2

8 11.1 80.2 14.9 64.5

9 11.3 73.2 14.9 59.2

10 12.1 69.6 21.9 55.6

11 13.9 96.1 21.9 73.8

12 15.3 106.2 21.9 79.5

13 15.4 150.5 21.9 107.3

14 16.9 211.2 21.9 148.9

15 17.8 255.7 21.9 180.1

16 15.7 111.7 21.9 83.5

17 14.0 71.0 21.9 55.7

18 14.0 74.4 21.9 58.4

19 11.9 72.5 14.9 58.7

20 11.1 59.8 14.9 49.0

21 11.7 70.6 14.9 57.2

22 8.8 63.0 14.9 51.5

23 8.5 66.9 14.9 54.4

24-Hour Avg. 107.0 81.7

Note: High wind hours are highlighted in bold italics.

6 - 27
Table 6-15

2012 Attainment Demonstration 

High Wind Design Day (June 6, 2007) at the Durango Complex Monitor

Hour Wind

Speed

(mph)

June 6, 2007 PM-10

Concentration

(μg/m3

)

 Background

Concentration

(μg/m3

)

2012 Controlled PM-10

Concentration

(μg/m3

)

0 8.9 132.6 14.9 92.2

1 6.3 166.4 14.9 114.4

2 5.0 133.6 14.9 92.9

3 1.0 112.7 14.9 79.2

4 2.6 124.4 14.9 86.8

5 7.3 101.4 14.9 71.7

6 9.1 164.5 14.9 113.2

7 8.7 113.4 14.9 79.6

8 10.5 93.6 14.9 66.6

9 11.2 86.3 14.9 61.8

10 11.9 83.3 14.9 59.8

11 12.5 130.3 21.9 94.8

12 13.9 168.1 21.9 121.4

13 13.5 202.7 21.9 145.4

14 15.7 405.5 21.9 275.9

15 17.9 398.1 21.9 276.5

16 14.5 119.9 21.9 87.1

17 12.9 70.0 21.9 54.9

18 10.3 53.9 14.9 40.5

19 8.9 57.0 14.9 42.6

20 6.4 61.1 14.9 45.3

21 7.5 83.0 14.9 59.6

22 6.3 67.8 14.9 49.7

23 5.2 79.6 14.9 57.4

24-Hour Avg. 133.7 94.6

Note: High wind hours highlighted in bold italics.

6 - 28
Table 6-16

2012 Attainment Demonstration 

High Wind Design Day (June 6, 2007) at the Greenwood Monitor

Hour

Wind

Speed

(mph)

June 6, 2007 PM-10

Concentration

(μg/m3

)

 Background

Concentration

(μg/m3

)

2012 Controlled PM-10

Concentration

(μg/m3

)

0 8.1 138.4 14.9 108.8

1 5.7 159.9 14.9 125.1

2 4.9 123.4 14.9 97.4

3 2.9 105.2 14.9 83.5

4 2.1 105.6 14.9 83.8

5 5.4 86.5 14.9 69.3

6 6.7 112.6 14.9 89.2

7 7.7 103.8 14.9 82.5

8 8.3 77.9 14.9 62.8

9 10.0 79.0 14.9 63.6

10 11.0 74.7 14.9 60.3

11 10.8 103.2 14.9 82.0

12 12.7 172.2 21.9 129.2

13 12.6 194.6 21.9 147.1

14 15.4 442.1 21.9 310.3

15 13.9 240.6 21.9 175.1

16 11.9 93.5 14.9 74.6

17 11.7 96.9 14.9 77.2

18 11.4 82.5 14.9 66.3

19 8.7 68.3 14.9 55.5

20 7.4 61.3 14.9 50.2

21 7.0 67.9 14.9 55.2

22 5.1 63.5 14.9 51.8

23 4.0 68.3 14.9 55.5

24-Hour Avg. 121.7 94.0

Note: High wind hours highlighted in bold italics.

6 - 29
Table 6-17

2012 Attainment Demonstration 

High Wind Design Day (June 6, 2007) at the Higley Monitor

Hour Wind

Speed

(mph)

June 6, 2007 PM-10

Concentration

(μg/m3

)

 Background

Concentration

(μg/m3

)

2012 Controlled PM-10

Concentration

(μg/m3

)

0 7.4 39.6 14.9 30.1

1 5.8 72.9 14.9 50.6

2 8.8 135.2 14.9 88.9

3 9.0 130.9 14.9 86.2

4 9.1 104.9 14.9 70.3

5 7.4 96.4 14.9 65.0

6 9.4 113.4 14.9 75.5

7 9.4 90.9 14.9 61.6

8 10.8 187.2 14.9 120.9

9 11.6 195.1 14.9 125.7

10 14.6 580.2 21.9 431.9

11 15.2 379.0 21.9 266.3

12 17.6 568.8 21.9 406.7

13 15.3 408.1 21.9 290.5

14 15.8 387.9 21.9 271.1

15 15.6 268.9 21.9 190.5

16 15.3 167.5 21.9 120.8

17 13.5 96.4 21.9 75.3

18 10.1 45.2 14.9 33.5

19 6.9 50.7 14.9 36.9

20 6.6 43.1 14.9 32.2

21 7.1 60.5 14.9 42.9

22 2.9 55.7 14.9 40.0

23 3.2 66.9 14.9 46.9

24-Hour Avg. 181.1 127.5

Note: High wind hours highlighted in bold italics.

6 - 30
Table 6-18

2012 Attainment Demonstration 

High Wind Design Day (June 6, 2007) at the State Super Site Monitor

Hour Wind

Speed

(mph)

June 6, 2007 PM-10

Concentration

(μg/m3

)

 Background

Concentration

(μg/m3

)

2012 Controlled PM-10

Concentration

(μg/m3

)

0 7.6 99.3 14.9 79.0

1 6.3 149.6 14.9 117.3

2 5.4 112.2 14.9 88.8

3 5.4 95.8 14.9 76.4

4 6.7 92.4 14.9 73.8

5 7.2 80.6 14.9 64.8

6 7.2 80.2 14.9 64.5

7 6.5 82.7 14.9 66.4

8 7.2 63.5 14.9 51.8

9 6.7 60.8 14.9 49.8

10 6.9 53.6 14.9 44.3

11 9.4 65.5 14.9 53.4

12 8.9 77.8 14.9 62.7

13 9.8 107.8 14.9 85.5

14 10.5 142.1 14.9 111.6

15 11.4 109.4 14.9 86.7

16 10.1 62.3 14.9 50.9

17 9.2 54.4 14.9 44.9

18 11.2 57.5 14.9 47.3

19 9.6 53.9 14.9 44.5

20 7.8 60.9 14.9 49.9

21 6.3 62.5 14.9 51.1

22 3.8 55.1 14.9 45.5

23 3.6 54.8 14.9 45.2

24-Hour Avg. 80.6 64.8

6 - 31
Table 6-19

2012 Attainment Demonstration 

High Wind Design Day (June 6, 2007) at the West Phoenix Monitor

Hour Wind

Speed

(mph)

June 6, 2007 PM-10

Concentration

(μg/m3

)

 Background

Concentration

(μg/m3

)

2012 Controlled PM-10

Concentration

(μg/m3

)

0 7.1 134.4 14.9 105.7

1 7.8 164.9 14.9 128.9

2 8.4 123.8 14.9 97.7

3 4.2 106.1 14.9 84.2

4 5.1 99.1 14.9 78.9

5 6.1 84.4 14.9 67.7

6 8.5 94.4 14.9 75.3

7 10.3 102.9 14.9 81.8

8 8.7 75.2 14.9 60.7

9 8.6 70.3 14.9 57.0

10 8.8 62.1 14.9 50.8

11 12.1 122.2 21.9 99.7

12 13.6 169.6 21.9 130.8

13 15.1 256.6 21.9 192.2

14 15.1 259.8 21.9 193.6

15 13.5 132.1 21.9 102.9

16 12.0 88.2 14.9 70.6

17 11.7 71.9 14.9 58.2

18 10.0 66.7 14.9 54.3

19 9.3 65.1 14.9 53.1

20 9.1 66.7 14.9 54.3

21 6.8 67.3 14.9 54.7

22 5.3 62.6 14.9 51.2

23 4.8 63.7 14.9 52.0

24-Hour Avg. 108.8 85.7

Note: High wind hours highlighted in bold italics.

6 - 32
Table 6-20

2012 Attainment Demonstration 

High Wind Design Day (June 6, 2007) at the West 43rd Avenue Monitor

Hour Wind

Speed

(mph)

June 6, 2007 PM-10

Concentration

(μg/m3

)

 Background

Concentration

(μg/m3

)

2012 Controlled PM-10

Concentration

(μg/m3

)

0 13.3 175.1 21.9 124.9

1 9.9 177.0 14.9 121.4

2 9.1 150.0 14.9 103.7

3 7.8 115.5 14.9 81.0

4 10.6 145.0 14.9 100.4

5 14.5 318.0 21.9 218.8

6 14.9 267.2 21.9 182.9

7 11.4 208.1 14.9 141.8

8 11.3 131.4 14.9 91.4

9 12.0 152.0 14.9 105.0

10 13.8 180.8 21.9 128.3

11 16.0 438.3 21.9 294.9

12 16.6 449.1 21.9 299.6

13 15.1 394.9 21.9 265.9

14 17.6 643.1 21.9 424.3

15 18.1 662.3 21.9 428.4

16 17.0 237.5 21.9 161.8

17 14.5 92.3 21.9 68.1

18 14.9 77.9 21.9 58.6

19 12.0 56.1 14.9 42.0

20 8.8 87.3 14.9 62.5

21 9.3 98.1 14.9 69.6

22 7.0 82.6 14.9 59.4

23 6.8 78.3 14.9 56.6

24-Hour Avg. 225.7 153.8

Note: High wind hours highlighted in bold italics.

6 - 33
REASONABLE FURTHER PROGRESS

Section 189(c) of the Clean Air Act establishes a requirement that the plan include

quantitative milestones that are to be achieved every three years until the area is

redesignated to attainment and which demonstrate reasonable further progress toward

attainment by the applicable date. Section 171(1) of the Clean Air Act defines

reasonable further progress as annual incremental reductions in emissions for the

purpose of ensuring attainment by the applicable date. 

For the MAG 2012 Five Percent Plan, the applicable attainment date is December 31,

2012. The MAG 2007 Five Percent Plan included fifty-three control measures, most of

which were implemented during the three years before the Plan was withdrawn in

January 2011. The measures were first implemented in 2008 and continue to be

implemented. The measures submitted in the MAG 2012 Five Percent Plan for PM-10

for approval into the Arizona SIP are listed in Table 4-1. Many of the measures from the

2007 Plan have been included in Table 4-1.

Although the 2007 Plan was withdrawn, EPA has approved Rules 310 and 310.01

(EPA, 2010) and Rule 316 (EPA, 2009), into the State Implementation Plan as

permanent and enforceable measures. Increases in rule effectiveness are attributable

to strengthened enforcement and increased compliance with these rules. Increased

rule effectiveness resulted in major reductions in PM-10 emissions throughout the

nonattainment area in 2008 through 2010. 

Attainment can not be achieved prior to December 31, 2012, because the Dust Action

General Permit measure needed for attainment modeling was not fully implemented

until January, 2012. Additionally, according to the form of the PM-10 standard, three

years of clean data are needed in order to demonstrate attainment (e.g., 2009-2011). 

There were several exceedances of the 24-hour PM-10 standard in 2009 and 2011

which may be due to high wind exceptional events and the required documentation for

these events has not yet been submitted to EPA for concurrence. It is unknown if three

years of clean data will be available for attainment by December 31, 2011 until ADEQ

submits and EPA acts upon the exceedances due to high wind exceptional events in

2009 and 2011. Because emission reductions from the Dust Action General Permit in

2012 are needed to model attainment and EPA concurrence on exceptional events in

2009 and 2011 is outstanding, the earliest attainment date achievable by this Plan is

December 31, 2012. 

According to the General Preamble, nonattainment area plans must include quantitative

milestones which are to be achieved every three years until the area is redesignated to

attainment. The quantitative milestones allow progress to be measured. Specifically,

air quality plans should identify and submit quantitative milestones providing for the

amount of emission reductions adequate to achieve the standard by the attainment

date. The milestone date analyzed in this Plan is 2012. The modeling for the Salt River

Area and the PM-10 nonattainment area has shown that the emissions reductions due

6 - 34
to increased rule effectiveness for Maricopa County Rules 310, 310.01 and 316 and

implementation of the Dust Action General Permit measure are adequate to achieve

attainment by 2012. The requirement for a 2012 milestone has been addressed by

quantifying the emission reductions resulting from the implementation of the Dust Action

General Permit measure and increases in rule effectiveness for Rules 310, 310.01 and

316. As shown in Table 5-3, the milestone PM-10 emissions reduction needed to

achieve attainment in 2012 is 16,089 tons.

The annual incremental reductions that demonstrate reasonable further progress (RFP)

between 2007 and 2012 are graphed in Figure 6-6. After 2007, the RFP line represents

total emissions in the PM-10 nonattainment area after credit is applied for the increases

in rule effectiveness described in Chapter Five. The RFP requirement is met by

showing incremental emission reductions sufficient to maintain linear progress towards

attainment. The annual emissions in Figure 6-6 show a downward linear trend. The

slope of the line becomes less steep after 2008, because most of the increases in the

rule effectiveness for Rules 310, 310.01 and 316 were achieved in 2008. Figure 6-6

demonstrates that RFP will be achieved between 2007 and the attainment date of 2012. 

CONTINGENCY REQUIREMENTS

Measures in the MAG 2007 Five Percent Plan that strengthen and increase

enforcement of Rules 310, 310.01 and 316, as well as the Dust Action General Permit,

have been quantified to meet the annual five percent requirement, model attainment,

and demonstrate reasonable further progress (RFP). Additional emission reduction

benefits beyond those quantified in Chapter Five are needed to meet the contingency

requirements of the Clean Air Act. 

Section 172(c)(9) of the Clean Air Act requires that nonattainment plans contain

contingency measures. Such measures are to be undertaken without further action by

the State or the EPA Administrator if the area fails to make reasonable further progress

or meet the standard by the attainment date. 

The contingency measures must achieve emission reductions above and beyond those

relied upon for progress (five percent reductions, milestones, and reasonable further

progress) and the modeled attainment demonstration. The benefits of the contingency

measures must not be required to show attainment and can not hasten attainment. 

Although there is no mandated emissions reduction level, EPA has recommended that

contingency measures provide the emissions reduction equivalent of one year’s

average increment of RFP. EPA encourages early implementation of contingency

measures to reduce emissions as expeditiously as practicable (EPA, 1993). The

contingency requirement is met in the MAG 2012 Five Percent Plan by quantifying the

benefits of PM-10 reduction projects that were completed in 2008-2011. 

6 - 35
Figure 6-6

Demonstration of Reasonable Further Progress

6 - 36
A large number of PM-10 reduction projects have been implemented in the PM-10

nonattainment area since the MAG 2007 Five Percent Plan was submitted to EPA in

December 2007. As required for contingency measures, the emission reductions

attributable to these projects are above and beyond the credit taken for the measures in

Chapter Five. In the Fall of 2011, MAG updated the inventory of PM-10 reduction

projects in the nonattainment area that were completed in 2008-2011 by the cities,

towns, Maricopa County, Pinal County, the Arizona Department of Transportation

(ADOT) and the Indian communities. These projects included paving and stabilizing

unpaved roads, alleys and shoulders; reducing speed limits on unpaved roads and

alleys; and overlaying state highways with rubberized asphalt. In addition, MAG

quantified the benefit for the freeways being swept by an ADOT contractor with PM-10

certified street sweepers and the arterials being swept by local jurisdictions with 25 PM10 certified street sweepers purchased with Congestion Mitigation and Air Quality

Improvement (CMAQ) funds in 2007 through 2009.

Figure 6-6 indicates that the total PM-10 emissions in 2007 are 59,218 tons; after

reductions due to the increases in rule effectiveness discussed in Chapter Five, PM-10

emissions are reduced to 43,130 tons in 2012. Subtracting these two values and

dividing by five years produces a contingency target of 3,218 tons. Therefore,

completed projects that reduce total PM-10 emissions by at least 3,218 tons in 2012

must be quantified to meet the contingency target. A summary of the miles of roads,

alleys and shoulders impacted by the paving and stabilization, speed limit reduction,

and rubberized asphalt overlay projects that were quantified to meet the contingency

requirement is presented in Table 6-21. These PM-10 reduction projects were

implemented in the PM-10 nonattainment area by twenty-one cities and towns,

Maricopa County, Pinal County, ADOT and the Gila River Indian Community. All of the

projects for which credit was taken were open to traffic by September 2011.

The emission reductions for all measures quantified to meet the contingency

requirement are summarized in Table 6-22. Table 6-22 includes the benefits of the PM10 certified street sweeping on freeways and arterials, as well as the projects completed

in 2008-2011 that paved and stabilized unpaved roads, alleys and shoulders; reduced

speed limits; and overlaid highways with rubberized asphalt. A detailed discussion of

the assumptions used in quantifying the PM-10 reductions needed to meet the

contingency requirement is provided in Chapter IV of the TSD (Appendix B, Exhibit 1). 

The total PM-10 emissions reduction in 2012 is 3,439 tons, which exceeds the

contingency target of 3,218 tons by 221 tons. 

Table 6-23 shows the PM-10 emissions for 2008-2012 by source category after

increases in rule effectiveness and contingency reductions are applied. The total tons

quantified to meet the five percent reduction, attainment modeling, RFP and

contingency requirements is 19,527 in 2012. This represents a 33 percent reduction,

relative to 2007 emissions. A pie chart of the 2012 nonattainment area PM-10

emissions with the five percent measures and contingency projects is shown in Figure

6-7. 

6 - 37
Table 6-21

Miles of Roads/Alleys/Shoulders in PM-10 Reduction Projects

Miles Impacted by Project Type 2008 2009 2010 2011

Total

2008-2011

Miles of dirt roads paved 41 18 8 16 83

Miles of dirt roads stabilized 39 39 36 31 145

Miles of dirt alleys paved 66 4 0 63 134

Miles of dirt alleys stabilized 164 106 124 106 501

Total miles of roads/alleys paved & stabilized 310 168 168 216 862

Miles of dirt shoulders paved 70 107 49 6 233

Miles of curb and gutter paved 19 0 0 0 19

Miles of dirt shoulders stabilized 235 236 236 200 906

Total miles of shoulders paved & stabilized 324 343 285 207 1,158

Miles of roads/alleys with lower speed limits 7 11 3 0 20

Miles of highway overlaid w/rubberized asphalt 13 0 0 0 13

6 - 38
Table 6-22 

2008-2012 PM-10 Reductions to Meet Contingency Requirements

Completed Projects Implementing Entities

2008 20

Sweep streets with PM-10 certified sweepersContracted sweeping of freeways, ramps and frontageroads - 100% compliant, effective 2/20/1025 PM-10 certified sweepers purchased with CMAQfunds: 1/1/07-12/31/09

ADOT 0 

Cities, towns 59 

Total for Street Sweeping 59 

Pave or stabilize existing public dirt roads andalleysPaving/stabilization projects completed in 2008-2011

Cities, towns, Maricopa and Pinal County,

and Gila River Indian Community 461 1

Total for Road/Alley

Paving/Stabilization 461 1

Lower speed limits on dirt roads and alleysSpeed limits lowered in 2008-2011 Cities, towns, Maricopa County 4 

Total for Lower Speed Limits 4 

Pave or stabilize unpaved shouldersPaving/stabilization projects completed in 2008-2011 Cities, towns, Maricopa County 173 

Total for Shoulder Paving/Stabilizing 173 

Repave or overlay paved roads with rubberizedasphaltRubberized asphalt overlays completed in 2008-2011

ADOT 0 

Total for Overlays 0 

Total for Completed Projects 697 1

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Table 6-23

2008-2012 PM-10 Emissions with Five Percent Plan Measures 

and Contingency Projects

Source Category 2008 2009 2010 2011 2012

POINT 150 133 127 128 135

AREA

Fuel combustion 1,301 1,307 1,311 1,316 1,328

Commercial cooking 993 998 1,001 1,005 1,014

Construction (includes windblown dust) 8,355 5,333 4,139 4,014 4,073

Tilling, harvesting and cotton ginning 893 893 893 893 893

Travel on unpaved farm roads 731 731 731 731 731

Livestock 261 261 261 261 261

Travel on unpaved parking lots 2,422 2,434 2,441 2,451 2,473

Offroad recreational vehicles 2,180 2,191 2,198 2,206 2,226

Leaf blowers 895 899 902 906 914

Windblown agriculture 448 448 448 448 448

Other windblown sources 3,938 3,788 3,788 3,788 3,639

Fires 497 497 497 497 497

Mining/quarrying (includes windblown dust) 476 401 355 356 369

Travel on industrial paved/unpaved roads 472 382 331 333 351

Other industrial sources 976 865 828 832 877

NONROAD

Aircraft 184 152 142 143 146

Airport ground support equipment 27 23 21 20 20

Locomotives 34 34 34 34 34

Other nonroad equipment 1,683 1,661 1,641 1,595 1,513

ONROAD

Exhaust 2,836 2,647 2,371 1,843 1,407

Tire wear 256 254 255 255 259

Brake wear 758 767 771 773 787

Paved roads 7,922 7,857 7,578 7,534 7,772

Unpaved roads and alleys 9,847 8,854 7,999 7,461 7,525

Totals 48,534 43,810 41,062 39,823 39,691

Total PM-10 Emissions Reduction 2007-2012: 19,527 tons, 33.0%

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Figure 6-7

6 - 41
The emission reductions that have been quantified for contingency credit are not

required to meet the five percent requirement, model attainment, or demonstrate

reasonable further progress. In addition, these reductions will not hasten attainment. 

As discussed previously in this chapter, the earliest attainment date that can be

achieved is December 31, 2012, due to the need to take PM-10 reduction credit for the

new Dust Action General Permit in order to demonstrate attainment via rollback

modeling. This chapter demonstrates that PM-10 emissions will be reduced by 3,439

tons more than the reductions achieved by measures used to show progress and model

attainment. The early implementation of contingency projects in 2008-2011 is assisting

in producing the three years of clean data necessary to attain the standard at all

monitors by December 31, 2012. 

ONROAD MOBILE SOURCE EMISSIONS BUDGET FOR CONFORMITY

In accordance with the 1990 Clean Air Act Amendments, conformity requirements are

intended to ensure that transportation activities do not result in air quality degradation. 

Section 176 of the Amendments requires that transportation plans, programs, and

projects conform to applicable air quality plans before the transportation action is

approved by a Metropolitan Planning Organization (MPO). The designated MPO for the

Maricopa area is MAG.

Section 176(c) of CAAA provides the framework for ensuring that Federal actions

conform to air quality plans under section 110. Conformity to an implementation plan

means that proposed activities must not (1) cause or contribute to any new violation of

any standard in any area, (2) increase the frequency or severity of any existing violation

of any standard in any area, or (3) delay timely attainment of any standard or any

required interim emission reductions or other milestones in any area. 

EPA transportation conformity regulations establish criteria involving comparison of

projected transportation plan emissions with the motor vehicle emissions assumed in

applicable air quality plans. The regulations define the term “motor vehicle emissions

budget” as meaning “the portion of the total allowable emissions defined in a revision of

the applicable implementation plan (or in an implementation plan revision which was

endorsed by the Governor or his or her designee) for a certain date for the purpose of

meeting reasonable further progress milestones or attainment or maintenance

demonstrations, for any criteria pollutant or its precursors, allocated by the applicable

implementation plan to highway and transit vehicles.”

On June 25, 2002, EPA approved the Revised MAG 1999 Serious Area Particulate Plan

for PM-10 in the Maricopa County Nonattainment Area, including the transportation

conformity budget for the attainment year of 2006. The 2006 onroad mobile source

emissions budget established for PM-10 was 59.7 metric tons per day. The PM-10 

emissions in the conformity budget included reentrained dust from paved roads, vehicle

exhaust, travel on unpaved roads, and road construction.

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The MAG 2012 Five Percent Plan establishes a transportation conformity budget based

on the measures implemented for the attainment year of 2012. The PM-10 emissions

with the measures that meet the five percent requirement, demonstrate modeled

attainment, and show reasonable further progress in 2012 are summarized in the table

below. 

2012 PM-10 Emissions from Onroad Mobile Sources (tons/year)

 Construction (road) 961

 Exhaust/tire wear/brake wear 2,456

 Paved roads (including trackout) 8,422

 Unpaved roads 10,312

 Total Onroad Mobile Source 22,151

Converting the annual tons per year to metric tons on an annual average day in 2012

produces PM-10 emissions of 54.9 metric tons per day for the PM-10 nonattainment

area. This represents the onroad mobile source emissions budget for the attainment

year of 2012.

MAG will use this new budget for conformity analyses that begin after the budget is

found to be adequate or is approved by EPA as part of the MAG 2012 Five Percent

Plan for PM-10. In conformity analyses that begin after the new budget is found to be

adequate or is approved, onroad mobile source PM-10 emissions for 2012 or horizon

years after 2012 can not exceed this budget. 

The methods and assumptions used to estimate onroad mobile source emissions in

2012 are documented in Chapter II of the TSD (Appendix B, Exhibit 1). In future

conformity analyses, the estimation of PM-10 emissions from onroad mobile sources

may differ from the TSD estimates, because EPA requires use of the latest planning

assumptions (e.g., new emissions models, vehicle registration data, vehicle speeds,

population and travel projections) in effect at the time each conformity analysis begins.

EXPEDITIOUS ATTAINMENT

The measures that have been quantified are being implemented throughout the PM-10

nonattainment area. As shown in Table 6-23, the measures are already reducing PM10 emissions from a variety of sources, including earthmoving, vacant lots, sand and

gravel operations, and unpaved roads, alleys and shoulders. The attainment

demonstration discussed earlier in this chapter indicates that the measures in the plan

will achieve modeled attainment at all monitors in the nonattainment area in 2012. The

current attainment date established by EPA’s final notice of failure to attain is June 6,

2012 (72 FR 31183). However, because of the calendar year form of the PM-10

standard, a mid-year attainment date of June 6, 2012 in effect requires attainment at all

monitors by December 31, 2011. 

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The attainment date can not be expedited (from June 6, 2012 to December 31, 2011),

because the emissions reduction credit from the Dust Action General Permit needed to

model attainment is not available in 2011, as this measure was not fully implemented

until January 1, 2012. Expediting measures in the plan is also not feasible, because all

measures except the Dust Action General Permit were already fully implemented by

2010. 

In addition, the attainment modeling for the nonattainment area demonstrates that the

24-hour PM-10 standard will be met by a relatively narrow margin in 2012 (i.e., 153.8

ug/m3 at the West 43rd Avenue monitor). The benefits of the measures in 2011 (i.e.,

without full implementation of the Dust Action General Permit) are not sufficient to

model attainment in 2011.

For the reasons discussed above, the measures in the Five Percent Plan demonstrate

attainment as expeditiously as practicable. The measures that were implemented 

throughout the nonattainment area in 2008-2011, along with the new Dust Action

General Permit measure, (fully implemented on January 1, 2012) enables attainment of

the 24-hour PM-10 standard at all monitors by December 31, 2012. 

ATTAINMENT DATE

On July 25, 2002, EPA published a notice of final approval for the Revised MAG 1999

Serious Area Particulate Plan for PM-10 for the Maricopa County Nonattainment Area. 

In this notice EPA also approved a five-year extension of the attainment date from

December 31, 2001 to December 31, 2006 (67 FR 48718).

On June 6, 2007, EPA published a final notice finding that the Maricopa County

nonattainment area had failed to attain the PM-10 standard by the applicable attainment

date of December 31, 2006 (72 FR 31183). The EPA finding was based upon air

quality monitoring data for the years 2004 through 2006. There were numerous

exceedances of the PM-10 standard during stagnant conditions in 2005 and 2006. As a

result, plan provisions that reduce PM-10 emissions by five percent per year until the

standard is met are required by Section 189(d) of the Clean Air Act. The MAG 2012

Five Percent Plan has been prepared to meet the five percent reduction requirements,

discussed in Chapter Five, as well as the attainment modeling, reasonable further

progress, and contingency requirements addressed earlier in this Chapter. 

EPA’s June 6, 2007 final notice of failure to attain establishes the attainment deadline

for an area that misses the serious area attainment date, 

“In accordance with CAA section 179(d)(3), the attainment deadline applicable to

an area that misses the serious area attainment date is as soon as practicable,

but no later than 5 years from the publication date of the nonattainment finding

notice. EPA may, however, extend the attainment deadline to the extent it

deems appropriate for a period no greater than 10 years from the publication

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date, ‘considering the severity of nonattainment and the availability and feasibility

of pollution control measures.’” (72 FR 31184)

The attainment deadline based upon EPA’s final notice is no later than June 6, 2012

unless EPA deems an extension is appropriate. Under stagnant conditions, the PM-10

standard has not been violated since 2006. The attainment modeling in this Chapter

demonstrates that the standard will also be met under high wind conditions throughout

the nonattainment area in 2012. 

Attainment of the 24-hour PM-10 standard is measured in terms of the number of

exceedances in a three-year period (no more than three exceedances at any monitor in

the nonattainment area over a three-year period, e.g., 2010-2012). It is anticipated that

attainment of the PM-10 standard will be achieved at all monitors in the nonattainment

area by December 31, 2012, after three consecutive years (2010-2012) without

monitored violations. As described earlier in this chapter, the MAG 2012 Five Percent

Plan can not demonstrate attainment via modeling without taking credit for the Dust

Action General Permit that will increase rule effectiveness for Rule 310.01 by one

percent on high wind days. This emerging measure, which was fully implemented on

January 1, 2012, will reduce PM-10 emissions during high wind conditions in 2012,

enabling the Plan to demonstrate modeled attainment in 2012. Since modeled

attainment can not be demonstrated until 2012 and three calendar years of clean data

are needed to demonstrate attainment at all PM-10 monitors in the nonattainment area,

the attainment date addressed by this Plan is December 31, 2012.

REQUEST FOR EXTENSION OF THE ATTAINMENT DATE FROM JUNE 6, 2012 TO

DECEMBER 31, 2012

As discussed in the preceding sections, the current attainment deadline based upon

EPA’s final notice of failure to attain is June 6, 2012. In order to meet the current midyear attainment date of June 6, 2012, the calendar year form of the 24-hour EPA PM-10

standard requires three years of clean data (2009-2011) at the monitors and modeled

attainment by December 31, 2011. As demonstrated in the attainment modeling

sections earlier in this chapter, modeled attainment can only be achieved in 2012, as

the Dust Action General Permit measure does not become fully implemented until

January 1, 2012. Modeled attainment cannot be demonstrated at all the monitors

without taking emission reduction credit for this new measure. Also, it is unknown if

clean data for years 2009-2011 will be available for attainment by December 31, 2011

until ADEQ submits and EPA acts upon documentation packages for several high wind

exceptional events exceedances. As such, an extension of the attainment deadline

from June 6, 2012 to December 31, 2012 is needed.

As stated in the June 6, 2007 final notice of failure to attain, authority to extend the

attainment deadline beyond June 6, 2012 is available to EPA,

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“EPA may, however, extend the attainment deadline to the extent it deems

appropriate for a period no greater than 10 years from the publication date,

‘considering the severity of nonattainment and the availability and feasibility of

pollution control measures.’” (72 FR 31184) 

For this Plan, the justification for an extension of the attainment deadline from June 6,

2012 to December 31, 2012 is centered around the availability of the new Dust Action

General Permit measure, which was not fully implemented until January 1, 2012. 

Modeled attainment at all the monitors in the nonattainment area cannot be achieved

under high wind conditions without the emissions reductions associated with the Dust

Action General permit. 

Development of the MAG 2012 Five Percent Plan was centered on addressing the

technical approvability issues identified by EPA in their September 9, 2010 proposed

partial disapproval of the MAG 2007 Five Percent Plan for PM-10 (75 FR 54806). 

These approvability issues established the need for a new emissions inventory and high

wind modeling attainment demonstration in the MAG 2012 Five Percent Plan.

In February 2011, to begin addressing the technical approvability issues identified by

EPA, a broad stakeholders group consisting of public and private entities was formed by

ADEQ to discuss possible policy options for the MAG 2012 Five Percent Plan. Also

meeting at the same time was a Five Percent Plan Technical Committee created to

produce a new emissions inventory, conduct a high wind modeling attainment

demonstration and address other technical issues as needed. EPA representatives

participated regularly in both of these groups.

As of January 2012, the stakeholders group has met 16 times and the technical

committee 20 times. The stakeholders group was involved in crafting a new measure to

reduce fugitive dust on high wind days, the Dust Action General Permit. The Arizona

Legislature passed House Bill 2208 in April 2011, which authorized the creation of the

Dust Action General Permit. The Dust Action General Permit went through public notice

and hearing and was signed and issued on December 30, 2011. 

In order to model attainment during high winds at all the monitors in the PM-10

nonattainment area, the Five Percent Plan Technical Committee in consultation with

EPA settled on the rollback modeling methodology for the MAG 2012 Five Percent Plan

in August 2011. However, the high wind days to be modeled to demonstrate attainment

were not agreed upon by the Five Percent Plan Technical Committee until October,

2011. After applying the rollback methodology to the selected days, it was determined

that attainment could not be demonstrated without emissions reduction credit for the

Dust Action General Permit. Since the Dust Action General Permit was signed on

December 30, 2011, full implementation of this measure did not occur until 2012. As

such, modeled attainment under high wind conditions at all monitors can only be shown

in 2012, necessitating the need for an extension of the attainment deadline to

December 31, 2012.

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In summary, the process of addressing the technical approvability issues suggested by

EPA resulted in the development of a new 2008 emissions inventory and the rollback

conceptual model and design days selected for attainment modeling. These new

technical pieces also identified the need for additional control of high wind fugitive dust

beyond existing measures. Once identified, the feasibility of fully implementing the new

control measure in order to model attainment under high wind conditions in 2011 was

not possible given the effective date of December 30, 2011 for the Dust Action General

Permit. As such, an extension from June 6, 2012 to December 31, 2012 is needed to

allow for a full year of implementation of the new Dust Action General Permit required to

demonstrate attainment at all monitors in 2012. 

6 - 47
REFERENCES

EPA, 1993. Early Implementation of Contingency Measures for Ozone and Carbon

Monoxide (CO) Nonattainment Areas. August 13, 1993.

MAG, 2000. Revised MAG 1999 Serious Area Particulate Plan for PM-10 for the

Maricopa County Nonattainment Area. February 2000.

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