MAG EIGHT-HOUR OZONE REDESIGNATION REQUEST

AND MAINTENANCE PLAN FOR 

THE MARICOPA NONATTAINMENT AREA

FEBRUARY 2009
MAG EIGHT-HOUR OZONE REDESIGNATION REQUEST

AND MAINTENANCE PLAN FOR 

THE MARICOPA NONATTAINMENT AREA

Prepared by:

FEBRUARY 2009

Technical Assistance Provided By:

Arizona Department of Environmental Quality

Arizona Department of Transportation

Maricopa County Air Quality Department

U.S. Environmental Protection Agency
i

MAG EIGHT-HOUR OZONE REDESIGNATION REQUEST AND MAINTENANCE PLAN

FOR THE MARICOPA NONATTAINMENT AREA

TABLE OF CONTENTS

CHAPTER PAGE

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

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

NATIONAL AMBIENT AIR QUALITY STANDARD

FOR OZONE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

CHARACTERISTICS AND HEALTH EFFECTS

OF OZONE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

NONATTAINMENT AREA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

REQUIRED COMPONENTS OF A REDESIGNATION

REQUEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

TWO REDESIGNATION REQUEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

REQUIRED COMPONENTS OF A REDESIGNATION

REQUEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

ATTAINMENT OF THE EIGHT-HOUR OZONE STANDARD . . . . . 2-1

APPROVAL OF THE OZONE NONATTAINMENT

SIP ELEMENT FOR THE MARICOPA AREA . . . . . . . . . . . . . . . . 2-8

IMPROVEMENT IN AIR QUALITY DUE TO PERMANENT

AND ENFORCEABLE EMISSION REDUCTIONS . . . . . . . . . . . . . 2-8

COMMITTED MEASURES USED FOR NUMERIC CREDIT 

 IN THE MAINTENANCE DEMONSTRATION . . . . . . . . . . . . . . . 2-12

CLEAN AIR ACT SECTION 110 AND

PART D REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-17
ii

CHAPTER PAGE

THREE MAINTENANCE PLAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

DESCRIPTION OF CONTROL MEASURES FOR 

THE MAINTENANCE PERIOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

EMISSION INVENTORIES FOR THE BASE AND 

FUTURE YEARS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10

MAINTENANCE DEMONSTRATION . . . . . . . . . . . . . . . . . . . . . . 3-16

MOBILE SOURCE EMISSION BUDGETS . . . . . . . . . . . . . . . . . . 3-19

AN APPROVED MONITORING NETWORK AND 

VERIFICATION OF CONTINUED ATTAINMENT . . . . . . . . . . . . 3-20

CONTINGENCY PROVISIONS . . . . . . . . . . . . . . . . . . . . . . . . . . 3-21

SUBSEQUENT MAINTENANCE PLAN REVISIONS . . . . . . . . . . 3-22

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R-1
iii

MAG EIGHT-HOUR OZONE REDESIGNATION REQUEST AND MAINTENANCE PLAN 

FOR THE MARICOPA NONATTAINMENT AREA

APPENDICES

APPENDIX A

Exhibit 1: 2005 Periodic Emission Inventory for Ozone Precursors for the Maricopa

County, Arizona, Nonattainment Area. September 2008.

Exhibit 2: Technical Support Document for Ozone Modeling in Support of the

Eight-Hour Ozone Redesignation Request and Maintenance Plan for the

Maricopa Nonattainment Area. February 2009.

APPENDIX B

Exhibit 1: Public Hearing Process Documentation

Exhibit 2: Certification of Adoption
iv

MAG EIGHT-HOUR OZONE REDESIGNATION REQUEST AND MAINTENANCE PLAN

FOR THE MARICOPA NONATTAINMENT AREA

LIST OF TABLES

TABLE PAGE

ES-1 Committed Maintenance Measures and Contingency Measures

in the Eight-Hour Ozone Maintenance Plan . . . . . . . . . . . . . . . . . . . . . . . . . ES-4

ES-2 VOC Emissions for a June Episode Day in 2005 and 2025 . . . . . . . . . . . . . ES-8

ES-3 NOx Emissions for a June Episode Day in 2005 and 2025 . . . . . . . . . . . . . . ES-9

2-1 2005 Ozone Monitoring Data Summary for the Maricopa Nonattainment

 Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

2-2 2006 Ozone Monitoring Data Summary for the Maricopa Nonattainment

Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

2-3 2007 Ozone Monitoring Data Summary for the Maricopa Nonattainment

Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

2-4 2008 Ozone Monitoring Data Summary for the Maricopa Nonattainment

Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6

2-5 Eight-Hour Ozone Monitoring Data Summary, Three-Year Average of the 

Fourth-High, 2005-2008 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9

2-6 Maricopa County VOC RACT Rules and SIP Status . . . . . . . . . . . . . . . . . . . . 2-24

3-1 Committed Maintenance Measures and Contingency Measures

in the Eight-Hour Ozone Maintenance Plan. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3

3-2 2025 Emission Reductions for Individual Maintenance Measures

in Metric Tons per Day. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

3-3 2025Anthropogenic VOC Emissions With and Without the Maintenance

Measure Package (MMP). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8

3-4 2025Anthropogenic NOx Emissions With and Without the Maintenance

Measure Package (MMP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9

3-5 Key Assumptions Used to Develop 2005 and 2025 Emissions for the 
v

Maintenance Demonstration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12

3-6 VOC Emissions for a June Episode Day in 2005 and 2025. . . . . . . . . . . . . . . 3-14

3-7 NOx Emissions for a June Episode Day in 2005 and 2025. . . . . . . . . . . . . . . 3-15

3-8 Maximum Modeled Eight-Hour Ozone Concentrations for the

June, July and August Episodes in 2025 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-17
vi

MAG EIGHT-HOUR OZONE REDESIGNATION REQUEST AND MAINTENANCE PLAN

FOR THE MARICOPA NONATTAINMENT AREA

LIST OF FIGURES

FIGURE PAGE

ES-1 Eight-Hour Ozone Trends (2000-2008) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ES-2

ES-2 2025 Anthropogenic VOC Emission Reductions for Individual

Maintenance Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ES-5

ES-3 2025 Anthropogenic NOx Emission Reductions for Individual

Maintenance Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ES-6

ES-4 Predicted Eight-Hour Ozone Concentrations in June 2025 (in ppb) . . . . . . ES-11

1-1 Air Quality Nonattainment and Maintenance Areas for the Maricopa

County Area, Arizona . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

2-1 Eight-Hour Ozone Regional Monitoring Network . . . . . . . . . . . . . . . . . . . . . . . . 2-7

2-2 Eight-Hour Ozone Trends (2000-2008) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10

3-1 2025 Anthropogenic VOC Emission Reductions for Individual

Maintenance Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

3-2 2025 Anthropogenic NOx Emission Reductions for Individual

Maintenance Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6

3-3 Predicted Eight-Hour Ozone Concentrations in June 2025 (in ppb) . . . . . . . . 3-18
MAG EIGHT-HOUR OZONE REDESIGNATION REQUEST

AND MAINTENANCE PLAN FOR 

THE MARICOPA NONATTAINMENT AREA

EXECUTIVE SUMMARY
ES-1

MAG EIGHT-HOUR OZONE REDESIGNATION REQUEST AND MAINTENANCE

PLAN FOR THE MARICOPA NONATTAINMENT AREA

EXECUTIVE SUMMARY

On July 18, 1997, the U.S. Environmental Protection Agency (EPA) promulgated an eighthour ozone standard of 0.08 parts per million (ppm). The Maricopa Association of

Governments (MAG) is requesting that EPA redesignate the Maricopa area to attainment

for the 1997 eight-hour ozone standard. No violations of this standard have occurred since

2004. With the submittal of this redesignation request and maintenance plan, the Maricopa

nonattainment area has satisfied all of the requirements for redesignation to attainment for

the 1997 eight-hour ozone standard.

In March 2008, EPA promulgated a new, more stringent eight-hour ozone standard of

0.075 ppm. Lawsuits challenging the new standard have been filed in federal court. MAG

will conduct the modeling and technical analyses and prepare the plans required by the

Clean Air Act, after EPA designates the nonattainment areas and publishes

implementation guidance for the new ozone standard.

The Maricopa area was designated nonattainment for the 1997 eight-hour ozone standard,

effective June 15, 2004. The Maricopa nonattainment area was classified as “Basic” under

Part D, Subpart 1, of the Clean Air Act. Basic nonattainment areas were required to submit

a plan to EPA by June 15, 2007 that demonstrated attainment of the eight-hour ozone

standard by June 15, 2009. 

In accordance with the Clear Air Act, MAG submitted the Eight-Hour Ozone Plan for the

Maricopa Nonattainment Area to EPA by June 15, 2007. This plan demonstrated, through

modeling and supporting technical analyses, that the eight-hour ozone standard would be

met by June 15, 2009. Air quality monitoring data indicated that the area attained the eighthour ozone standard in 2005 and that the area has continued to meet the standard since

then (i.e., 2006, 2007, and 2008).

The Clean Air Act defines the following criteria that must be met before a nonattainment

area may be redesignated to attainment:

• EPA must determine that the area has attained the eight-hour ozone standard.

• EPA must determine that the improvement in air quality is due to permanent and

enforceable reductions in emissions.

• All applicable requirements for State Implementation Plans (SIPs) and

Nonattainment Areas defined in the Clean Air Act must be met.

• EPA must approve a maintenance plan for the area. The plan must demonstrate

maintenance of the eight-hour ozone standard for a period of at least ten years

following the redesignation to attainment by EPA. 

The maintenance plan in this document provides monitoring data to support the finding that

the eight-hour ozone standard has been met in the nonattainment area since 2005. Figure

ES-1 shows the downward trend in peak ozone concentrations that have occurred since
ES-2

FIGURE ES-1

EIGHT-HOUR OZONE TRENDS

(2000-2008)

* Due to mathematical rounding, values $0.085 ppm are necessary to exceed the

standard.

% Preliminary data through September 30, 2008. Quality assurance of the data is

in progress.

Monitors Where the Highest 3-Year Average of the 4th-Highest 8-Hour Ozone

Concentration Occurred:

(HM) Humboldt Mountain

(MO) Mount Ord

(NP) North Phoenix

(PP) Pinnacle Peak

(RV) Rio Verde

Sources: Environmental Protection Agency Air Quality System and Monitor Values

Report; Arizona Department of Environmental Quality.
ES-3

2000. The redesignation request in this document also demonstrates that these

improvements in air quality are attributable to permanent and enforceable reductions in

ozone precursor emissions and that other Clean Air Act requirements for SIPs and

nonattainment areas have been met.

Generally, the approach taken in preparing the Eight-Hour Ozone Redesignation Request

and Maintenance Plan is to rely on the legally-binding committed measures in programs

and plans that have already been approved by EPA. These include the Modified Arizona

Cleaner Burning Gasoline Program, approved by EPA on April 5, 2004; the Serious Area

Carbon Monoxide Plan and Carbon Monoxide Maintenance Plan, approved by EPA on

April 8, 2005; and the Serious Area Ozone State Implementation Plan and the One-Hour

Ozone Maintenance Plan, approved by EPA on June 14, 2005. This approach was also

used for the Eight-Hour Ozone Plan submitted to EPA by June 15, 2007. 

Table ES-1 identifies the seven measures for which numeric emission reduction credit was

taken in modeling maintenance of the eight-hour ozone standard in 2025. Three of these

measures (i.e., Phased in Emission Test Cutpoints, One-Time Waiver from Vehicle

Emissions Test, and Tougher Enforcement of Vehicle Registration and Emission Test

Compliance) were committed measures in the Serious Area Carbon Monoxide Plan and

the Carbon Monoxide Maintenance Plan. The measure, Summer Fuel Reformulation:

California Phase 2 and Federal Phase II Reformulated Gasoline with 7 psi from May 1

though September 30, was part of the Modified Arizona Cleaner Burning Gasoline Program

and was also a committed measure in the One-Hour Ozone Maintenance Plan. 

Two other maintenance measures, Federal Nonroad Equipment Emissions Standards and

Expansion of Area A Boundaries (HB 2538), were contingency measures in the MAG EightHour Ozone Plan for the Maricopa Nonattainment Area. The seventh measure for which

credit is taken is Ban Open Burning During Ozone Season. This new ozone measure was

passed by the Arizona Legislature in June 2007 as part of S.B. 1552. Figures ES-2 and

ES-3 show the VOC and NOx emission reductions attributable to each of the individual

maintenance measures in 2025. 

To meet the requirements for redesignation to attainment, this document includes an eighthour ozone maintenance plan for the Maricopa nonattainment area. The maintenance plan

demonstrates, through photochemical grid modeling and supporting technical analyses,

that the eight-hour ozone standard of 0.08 parts per million (ppm) will continue to be

maintained through 2025, a period of at least ten years following redesignation to

attainment by EPA. Maintenance of the standard will be achieved, despite a 76 percent

increase in vehicle travel in the nonattainment area between 2005 and 2025. The more

stringent federal controls on emissions from light duty vehicles and nonroad equipment, as

well as commitments made by State, County, and local governments in prior air quality

plans and programs, will more than offset the future growth in the nonattainment area.
ES-4

TABLE ES-1

COMMITTED MAINTENANCE MEASURES AND CONTINGENCY MEASURES

IN THE EIGHT-HOUR OZONE MAINTENANCE PLAN

Maintenance Measures Used for Numeric Credit Contingency Measures

1. Summer Fuel Reformulation: California

Phase 2 and Federal Phase II Reformulated

Gasoline with 7 psi from May 1 through

September 30

1. Gross Polluter Waiver 

 Provision

2. Phased-In Emission Test Cutpoints

 (I/M 147 Program)

2. Increased Waiver Repair 

 Limit

3. One Time Waiver from Vehicle Emissions

Test

3. Federal Heavy Duty Diesel 

 Vehicle Emissions Standards

4. Tougher Enforcement of Vehicle

Registration and Emission Test Compliance

4. Coordinate Traffic Signal 

 Systems

5. Federal Nonroad Equipment Emissions 

 Standards

5. Develop Intelligent 

 Transportation Systems

6. Expansion of Area A Boundaries (HB 2538) 6. Liquid Leaker Test as part 

 of VEI Program

7. Ban Open Burning During Ozone Season
ES-5

FIGURE ES-2

2025 ANTHROPOGENIC VOC EMISSION REDUCTIONS

FOR INDIVIDUAL MAINTENANCE MEASURES
ES-6

FIGURE ES-3

2025 ANTHROPOGENIC NOx EMISSION REDUCTIONS

FOR INDIVIDUAL MAINTENANCE MEASURES
ES-7

For the maintenance plan, MAG applied an EPA-approved photochemical grid model (the

Comprehensive Air Quality Model with Extensions - CAMx) to simulate eight-hour ozone

concentrations under the meteorological and transport conditions that accompanied high

ozone episodes in June 2002, July 2002, and August 2001. The 2005 baseline emissions

and the 2025 emissions used to model maintenance on the worst-case June episode day

are shown in Tables ES-2 and ES-3. The 2025 emissions assume emission reduction

credit for the seven maintenance measures discussed above. The 2025 emissions also

take into account the major growth in regional population, employment and vehicle travel

that is projected to occur between 2005 and 2025. 

A comparison of 2005 and 2025 emissions in Tables ES-2 and ES-3 indicates that onroad

mobile source emissions decline by more than one-third for VOC and almost 30 percent

for NOx, while nonroad emissions are reduced by 21 percent for VOC and more than 50

percent for NOx. The reductions in onroad emissions occur despite a 76 percent increase

in vehicle travel between 2005 and 2025. The reductions in onroad and nonroad emissions

are due primarily to the replacement of older, high-polluting vehicles and equipment with

new models that meet more stringent federal emission standards. 

For VOC emissions, the combined share of onroad and nonroad source contributions

declines from 17 to 12 percent, while point and area source emissions increase from 14 to

21 percent, between 2005 and 2025. Biogenic sources contribute the largest share of VOC

emissions in both 2005 and 2025. Among the non-biogenic sources, area sources

contribute the most VOC in 2005 (12 percent) and 2025 (19 percent). 

For NOx, onroad mobile sources contribute the largest share of emissions in both 2005 and

2025. The combined onroad and nonroad share of NOx emissions decreases from 86

percent in 2005 to 60 percent in 2025. It is important to note, however, that power plants

were assumed to emit maximum levels of NOx in 2025, whereas the power plant emissions

in 2005 represent actual operating levels. This conservative modeling assumption increases

point source emissions from 4 percent of the total NOx emissions in 2005 to 24 percent in

2025.

The maximum eight-hour ozone concentrations predicted by modeling the June, July, and

August episodes in 2025 were 0.081 ppm, 0.079 ppm, and 0.079 ppm, respectively. Since

the maximum value for each episode is less than 0.08 ppm, when rounded to the nearest

0.01 ppm, the modeling demonstrates maintenance of the standard in 2025. 

To support the modeling results, MAG performed a number of supplemental technical

analyses. One analysis involved the application of EPA software to determine if portions

of the nonattainment area that are not near ozone monitors (i.e., unmonitored areas) will

also meet the standard in 2025. The unmonitored area analysis determined that the

maximum eight-hour ozone concentrations in 2025 would be 0.081 ppm for the June

episode, 0.079 ppm for the July episode, and 0.083 ppm for the August episode. Since all

of these values are less than the standard of 0.08 ppm, when rounded to the nearest 0.01

ppm, this analysis concluded that the standard would not be exceeded in portions of the 
ES-8

TABLE ES-2

VOC EMISSIONS FOR A JUNE EPISODE DAY IN 2005 AND 2025

Source

Category

Thursday in June,

2005

(metric tons/day)

Thursday in June,

2025

(metric tons/day)

2025-2005 Difference

(%)

Point 11.1 18.7 68.5

Area 79.2 124.8 57.5

Nonroad 40.3 31.8 -21.0

Onroad 72.1 47.9 -33.6

Biogenics 451.3 451.3 0.0

Total 653.9 674.4 3.1

Sources:

Point - Industrial, Manufacturing, and Electrical Power Generation Facilities

Area - Chemical Solvent Use; Industrial Processes; Storage and Transport of Fuels;

Waste Treatment and Disposal; Residential and Industrial Fuel Combustion;

Open Burning; and Wildfires

Nonroad - Utility, Lawn & Garden, Construction, Farm, and Recreational Equipment;

Aircraft; and Locomotives

Onroad - Cars and Trucks Traveling on Paved and Unpaved Roads

Biogenics - Natural Vegetation

Note: The sum of the source categories may not equal the total due to rounding.

VOC for a Thursday in June, 2005

Total: 653.93 metric tons/day

Biogenics

69.0%

Nonroad

6.2%

Onroad

11.0%

Area

12.1%

Point

1.7%

VOC for a Thursday in June, 2025

Total : 674.42 metric tons/day

Point

2.8% Area

18.5%

Onroad

7.1%

Nonroad

Biogenics 4.7%

66.9%
ES-9

TABLE ES-3

NOx EMISSIONS FOR A JUNE EPISODE DAY IN 2005 AND 2025

Source

Category

Thursday in June,

2005

(metric tons/day)

 Thursday in June,

2025

(metric tons/day)

2025-2005 Difference

(%)

Point 10.9 59.1 440.3

Area 19.6 31.1 58.8

Nonroad 77.7 37.9 -51.2

Onroad 154.3 109.8 -28.9

Biogenics 8.6 8.6 0.0

Total 271.1 246.4 -9.1

Sources:

Point - Industrial, Manufacturing, and Electrical Power Generation Facilities

Area - Chemical Solvent Use; Industrial Processes; Storage and Transport of Fuels;

Waste Treatment and Disposal; Residential and Industrial Fuel Combustion;

Open Burning; and Wildfires

Nonroad - Utility, Lawn & Garden, Construction, Farm, and Recreational Equipment;

Aircraft; and Locomotives

Onroad - Cars and Trucks Traveling on Paved and Unpaved Roads

Biogenics - Natural Vegetation

Note: The sum of the source categories may not equal the total due to rounding.

NOx for a Thursday in June, 2005

Total: 271.06 metric tons/day

Biogenics

3.2%

Nonroad

28.6%

Onroad

56.9%

Area

7.2%

Point

4.0%

NOx for a Thursday in June, 2025

Total: 246.39 metric tons/day

Onroad

44.6%

Area

12.6%

Point

24.0%

Biogenics

3.5% Nonroad

15.4%
ES-10

nonattainment area that are not near ozone monitors. The unmonitored area analysis, as

well as all other supporting technical analyses, corroborate the conclusion that the eighthour ozone standard will be maintained in the Maricopa nonattainment area through 2025.

Figure ES-4 provides an isopleth plot of the results of the unmonitored area analysis

overlaid with the values predicted by modeling each monitoring site on the June 2025

episode day. The eight-hour ozone concentrations are shown in parts per billion (ppb).

With the seven committed maintenance measures, the maintenance plan estimates that

onroad mobile sources will contribute 43.8 metric tons per day of VOC and 101.8 metric

tons per day of NOx in the eight-hour ozone nonattainment area in 2025. These emissions

represent the new transportation conformity budgets for VOC and NOx in 2025. 

The Clean Air Act requires that a maintenance plan also contain contingency provisions.

The maintenance plan contains six contingency measures that are shown in Table ES-1.

These measures have already been implemented in the Maricopa nonattainment area.

Early implementation of contingency measures is allowed by EPA. The maintenance plan

also describes the process and schedule to be followed if monitoring data indicates that

additional measures may be needed in the future. 
ES-11

FIGURE ES-4

PREDICTED EIGHT-HOUR OZONE CONCENTRATIONS IN JUNE 2025

(in ppb)

72

81

73.8

75.3

75.2

74.6

75.8

72.1

73.3

74.9

76.4

65.4

62.4

68.2

78.1

71.1

79.7

79.3

73.3

70.6

68.2

63

61.5

67.8

77.5

WP

NP

FF

GL

PP

CP

SS

SP

WC

TEMP

CC

DY

BE

LV

HM

BP

FH

RV

SUPR

AJ

CG

QC

MCPA

SAC

QV

300000 320000 340000 360000 380000 400000 420000 440000 460000 4800

366000036800003700000372000037400003760000
1-1

CHAPTER ONE

INTRODUCTION

The Maricopa Association of Governments (MAG) is requesting that the U.S.

Environmental Protection Agency (EPA) redesignate the Maricopa nonattainment area to

attainment for the National Ambient Air Quality Standard for eight-hour ozone of 0.08 parts

per million that was promulgated by EPA in 1997. The area was designated a

nonattainment area for the eight-hour ozone standard in April 2004, but has not violated

the standard since 2004. Therefore, the area is now eligible for redesignation. Chapter

Two contains the formal redesignation request and supporting documentation. Chapter

Three provides the Maintenance Plan which demonstrates continued attainment of the

eight-hour ozone standard through the year 2025.

In 1978, the Governor of Arizona designated the Maricopa Association of Governments as

the lead air quality planning agency for Maricopa County. Together with the State, MAG

is responsible for determining which elements of the State Implementation Plan will be

planned, implemented and enforced by State and local governments in Arizona. In 1992,

the Arizona Legislature recertified MAG as the regional air quality planning agency. MAG

coordinates with the Arizona Department of Environmental Quality, the Arizona Department

of Transportation, and the Maricopa County Air Quality Department in developing the plans

necessary to attain and maintain the national air quality standards.

This Redesignation Request and Maintenance Plan is reviewed and approved by the MAG

Air Quality Technical Advisory Committee, the MAG Management Committee, and the

MAG Regional Council. The MAG Air Quality Technical Advisory Committee was

established in 1995 with representatives from State, county, and local governments, private

industry, environmental groups, and the public-at-large. The Air Quality Technical Advisory

Committee makes recommendations to the MAG Management Committee on air quality

plans, projects, funding, and other pertinent issues.

The MAG Management Committee is composed of managers from each of the MAG

member agencies that include twenty-five cities and towns, the Fort McDowell, Salt River

Pima-Maricopa, and Gila River Indian Communities, Maricopa County, Regional Public

Transportation Authority and the Arizona Department of Transportation. The MAG

Management Committee makes recommendations to the MAG Regional Council. The

Regional Council is the MAG decision-making body and is primarily comprised of elected

officials from the MAG member agencies. 

MAG is also required to conduct a public hearing on this redesignation request and

maintenance plan in accordance with federal requirements. All public comments and

responses are provided in Appendix B.
1-2

NATIONAL AMBIENT AIR QUALITY STANDARD FOR OZONE

On July 18, 1997, EPA promulgated an eight-hour ozone standard of 0.08 parts per million

(ppm). In March 2008, EPA promulgated a new, more stringent eight-hour ozone standard

of 0.075 ppm. Lawsuits challenging the new standard have been filed in federal court.

MAG will conduct the modeling and technical analyses and prepare the plans required by

the Clean Air Act, after EPA designates the nonattainment areas and publishes

implementation guidance for the new ozone standard.

Compliance with the eight-hour standard is determined at each monitor by averaging the

annual fourth-highest eight-hour ozone concentration over three consecutive years. EPA

requires that the monitored eight-hour ozone values be rounded to the nearest 0.01 ppm,

which means that a violation occurs when the three-year average of the fourth-highest

monitored concentration is 0.085 ppm or higher. 

The MAG 2007 Eight-Hour Ozone Plan for the Maricopa Nonattainment Area

demonstrated, through modeling and supporting technical analyses, that the 1997 standard

would be attained by June 15, 2009. Chapter Two presents the ozone monitoring data that

confirms that the standard of 0.08 ppm will be met by this date; in fact, there have been no

violations of this ozone standard at any monitor in the nonattainment area since 2004. This

plan demonstrates maintenance through 2025 and requests that EPA redesignate the area

to attainment for the 1997 standard. The phrase “eight-hour ozone standard” used

throughout this document refers to the 1997 standard.

CHARACTERISTICS AND HEALTH EFFECTS OF OZONE

Ozone is not directly emitted from a source, but is produced by chemical reactions among

volatile organic compounds (VOC), nitrogen oxides (NOx), and other air pollutants, in the

presence of heat and sunlight. VOC and NOx are emitted by onroad vehicles and nonroad

engines. Other sources of these ozone precursor emissions include industrial,

manufacturing, and electrical power generation facilities; dry cleaners, service stations,

architectural coatings, consumer and commercial solvent use; and natural vegetation.

Peak ozone concentrations typically occur in the nonattainment area from May through

September when high temperatures are conducive to the formation of ozone. Due to

prevailing afternoon winds, ozone precursors and ozone can be transported to the

mountainous areas in the eastern and northern portions of the nonattainment area.

Ozone irritates the lungs and repeated exposure may cause permanent lung damage.

Symptoms of ozone exposure may include wheezing, coughing, and pain when taking a

deep breath. Children, persons with pre-existing respiratory conditions such as asthma,

and others who are active outdoors when ozone levels are high are most affected by the

adverse health effects of ozone. Even low levels of ozone may cause aggravated asthma,

reduced lung capacity, and make persons more susceptible to respiratory illnesses such

as pneumonia and bronchitis.
1-3

NONATTAINMENT AREA

The Maricopa eight-hour ozone nonattainment area encompasses 4,880 square miles

located in central Arizona. The nonattainment area boundaries are shown in Figure 1-1.

The area contains portions of twenty-five cities and towns, the Fort McDowell and Salt

River Pima-Maricopa Indian Communities, and unincorporated areas under the jurisdiction

of Maricopa County. The southeastern portion of the nonattainment area also includes the

Apache Junction area in Pinal County. The eight-hour ozone nonattainment area does not

include the Gila River Indian Community. 

According to a Special U.S. Census, the population of Maricopa County was 3.7 million in

2005. Most of these residents live and work within the nonattainment area boundaries.

The nonattainment area is located in the Salt River Valley at 1,100 feet above mean sea

level and the urban area is almost completely surrounded by mountains. 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. In general, the prevailing wind direction is from E/SE to W/SW, although the winds

can shift in the afternoon to a more westerly direction.

HISTORY

In accordance with the Clean Air Act, an urbanized portion of Maricopa County was

formally designated as a nonattainment area for ozone in 1978. Under the 1990 Clean Air

Act Amendments, the nonattainment area was classified as Moderate for ozone. In order

to meet the Moderate area requirements, the MAG 1993 Ozone Plan for the Maricopa

County Area was submitted to the Environmental Protection Agency by November 15,

1993. An Addendum to this Plan containing additional control measures was submitted to

EPA in March 1994.

On April 13, 1994, EPA issued an incompleteness finding on the 1993 Ozone Plan and

Addendum because the plan failed to include, in fully adopted and enforceable form, all of

the measures relied upon in the 15 percent demonstration. This action started a two year

FIP clock under CAA Section 110(c) for EPA to promulgate a 15 percent Rate of Progress

Federal Implementation Plan. In November 1994 the modeling attainment demonstration

for the 1993 Ozone Plan and Addendum was submitted to EPA, with a revision to the

modeling attainment demonstration following in April 1995. The MAG 1993 Ozone Plan

and Addendum, as well as the attainment demonstration, was found complete by EPA on

May 12, 1995.

On November 6, 1997, the nonattainment area was reclassified to Serious due to failure

to attain the ozone standard by November 15, 1996. The Serious Area reclassification was

effective on February 13, 1998. Following the outcome of a lawsuit filed to require that 
Apache

Junction

Fort

McDowell

Yavapai

Nation

Buckeye

Salt River Pima-Maricopa

Indian Community

Gila River

Indian Community

Fountain

Hills

Paradise

Valley

Litchfield Park

El

Mirage

Queen Creek

Scottsdale

Wickenburg

Cave Creek

Guadalupe

Youngtown

Gila Bend

Tolleson

Glendale

Surprise

Goodyear

Carefree

Chandler

Avondale

Gilbert

Phoenix

Peoria

Tempe

Mesa

74

51

£¤60

Loop

101

Loop

101

Loop

202

Loop

202

§ ̈¦17

£¤60

§ ̈¦10

§ ̈¦10

Legend

Carbon Monoxide Maintenance Area

8-Hour Ozone Nonattainment Area

PM10 Nonattainment Area

Area A (H.B.2538 - 2001)

Maricopa County

Existing Freeway

Planned Freeway

While every effort has been made to ensure the accuracy of this

information, the Maricopa Association of Governments makes no

warranty, expressed or implied, as to its accuracy and expressly

disclaims liability for the accuracy thereof.

Source: U.S. Environmental Protection Agency,

g:/dev/maps/AQ/85x11/aq_bounds_with_AreaA_MPA_gismag.mxd

AIR QUALITY NONATTAINMENT

AND MAINTENANCE AREAS FOR THE

MARICOPA COUNTY AREA, ARIZONA

5 0 5 10

Miles

Prepared by the Maricopa Association of Governments, April 2008

Municipal Planning Areas shaded

FIGURE 1-1

1-4
1-5

EPA enforce the Federal Implementation Plan provisions in Section 110(c) of the Clean Air

Act, EPA promulgated a Federal Implementation Plan for the 15 Percent Rate of Progress

requirement on May 27, 1998.

On December 14, 2000, the Serious Area Ozone State Implementation Plan for Maricopa

County was submitted to EPA by the Arizona Department of Environmental Quality (ADEQ,

2000). In accordance with Section 110 of the Clean Air Act, a completeness finding on the

Serious Area Ozone State Implementation Plan (SIP) was deemed by operation of law,

since a determination was not made by EPA within six months of receipt of the Plan. The

Serious Area Ozone SIP was approved by EPA on June 14, 2005. 

On May 30, 2001, EPA determined that the Maricopa County nonattainment area had

attained the one-hour ozone standard. The attainment determination was effective on June

29, 2001. EPA also determined that the serious area requirements for reasonable further

progress, attainment determinations, and contingency measures for the one-hour ozone

standard would not apply, as long as the area continued to attain the standard. 

The MAG One-Hour Ozone Redesignation Request and Maintenance Plan for the

Maricopa County Nonattainment Area was submitted to EPA in May 2004 (MAG, 2004).

On June 14, 2005, EPA approved the One-Hour Ozone Redesignation Request and

Maintenance Plan. On June 15, 2005, EPA revoked the one-hour ozone standard, which

was less stringent than the eight-hour ozone standard promulgated in July 1997. 

On April 30, 2004, EPA published the final rule designating eight-hour ozone nonattainment

areas, effective June 15, 2004. The Maricopa nonattainment area was classified as “Basic”

under Part D, Subpart 1, of the Clean Air Act, with an attainment date of June 15, 2009.

The Clean Air Act requires that the attainment demonstration for a “Basic” nonattainment

area be submitted to EPA three years after the effective date of the designation, which is

June 15, 2007. 

MAG submitted the Eight-Hour Ozone Plan for the Maricopa Nonattainment Area to EPA

by June 15, 2007 (MAG, 2007). The Plan demonstrated attainment, through modeling and

supporting technical analyses, by June 15, 2009. The monitoring data shown in Chapter

Two confirms the findings of the Eight-Hour Ozone Plan that the eight-hour ozone standard

will be attained by June 15, 2009.

 

REQUIRED COMPONENTS OF A REDESIGNATION REQUEST

Sections 107(d)(3)(D) and (E) of the Clean Air Act define the criteria that must be met

before an area can be redesignated to attainment. This redesignation request and

maintenance plan demonstrates that the Maricopa nonattainment area meets the five

required criteria, which are summarized below:
1-6

1. Attainment of the Standard

Chapter Two provides the ozone monitoring data that confirms that the area has attained

the eight-hour ozone standard promulgated by EPA in July 1997. 

2. State Implementation Plan Approval

MAG submitted the Eight-Hour Ozone Plan for the Maricopa Nonattainment Area to EPA

by June 15, 2007. In accordance with Section 110 of the Clean Air Act, a completeness

finding was deemed by operation of law, since a determination was not made by EPA

within six months of receipt of the Plan. To date, EPA has not approved the Eight-Hour

Ozone Plan, but may take action to approve the Eight-Hour Ozone Plan concurrently with

the approval of this Eight-Hour Ozone Redesignation Request and Maintenance Plan.

3. Improvement in Air Quality Due to Permanent and Enforceable Emission Reductions

Chapter Two presents the evidence that the improvement in air quality leading to

attainment and maintenance of the standard has been due to permanent and enforceable

reductions in ozone precursor emissions.

4. Clean Air Act Section 110 and Part D Requirements

Chapter Two discusses how requirements of Clean Air Act Section 110 (for SIPs) and Part

D (for nonattainment areas) are satisfied by the Eight-Hour Ozone Plan for the Maricopa

Nonattainment Area and the Maintenance Plan provided in Chapter Three of this

document. Some of these requirements are also satisfied by the Serious Area Ozone SIP

and the One-Hour Ozone Redesignation Request and Maintenance Plan, both of which

were approved by EPA on June 14, 2005. In addition, several of the committed measures

in the Revised MAG 1999 Serious Area Carbon Monoxide Plan for the Maricopa County

Nonattainment Area (MAG, 2001) and the Carbon Monoxide Redesignation Request and

Maintenance Plan for the Maricopa County Nonattainment Area (MAG, 2003), both of

which were approved by EPA on April 8, 2005, also reduce ozone and have therefore been

included in the Eight-Hour Ozone Maintenance Plan.

5. Maintenance Plan

Chapter Three contains the Maintenance Plan for the Maricopa Eight-Hour Ozone

Nonattainment Area. The Maintenance Plan demonstrates, through modeling and

supporting technical analyses, that the area will continue to attain the eight-hour ozone

standard through 2025, a period of at least ten years following redesignation to attainment

by EPA. The Maintenance Plan establishes transportation conformity budgets for 2025.

The Maintenance Plan also contains contingency measures that have been implemented

and describes the process and schedule that will be used to consider additional measures,

if needed. 
2-1

CHAPTER TWO

REDESIGNATION REQUEST

The Maricopa Association of Governments requests that the U.S. Environmental Protection

Agency (EPA) redesignate the Maricopa nonattainment area to attainment for the National

Ambient Air Quality Standard for eight-hour ozone of 0.08 parts per million (ppm)

established in 1997. EPA designated the area as an eight-hour ozone nonattainment area

in 2004, but the area has not violated the standard since 2004. Therefore, the area is

eligible for redesignation.

REQUIRED COMPONENTS OF A REDESIGNATION REQUEST

The EPA Administrator may not redesignate an area to attainment, unless the following

requirements of Section 107(d)(3)(E) of the Clean Air Act are met: 

1. The Administrator determines that the area has attained the national ambient air

quality standards.

2. The Administrator has fully approved the applicable implementation plan under

Section 110(k).

3. The Administrator determines that the improvement in air quality is due to

permanent and enforceable reductions in emissions.

4. The State has met all applicable requirements under Section 110 and Part D.

5. The EPA Administrator approves a maintenance plan for the area that meets the

provisions of Section 175A.

The first four redesignation requirements are addressed in this chapter. Chapter Three

contains the maintenance plan that is being submitted to EPA to fulfill the fifth and final

requirement.

ATTAINMENT OF THE EIGHT-HOUR OZONE STANDARD

Attainment of the 1997 National Ambient Air Quality Standard of 0.08 ppm for eight-hour

ozone is determined by averaging the annual fourth-highest eight-hour ozone concentration

at each monitor over three consecutive years. EPA requires that the monitored eight-hour

ozone values be rounded to the nearest 0.01 ppm, which means that a violation occurs

when the three-year average of the fourth-highest monitored concentration is 0.085 ppm

or higher. The following information demonstrates, as required by Section 107(d)(3)(E) of

the Clean Air Act, that the Maricopa nonattainment area has attained the eight-hour ozone

standard. This conclusion is based on quality assured data from the ozone monitors in the

nonattainment area.
2-2

Climatological Data

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 (NOAA, 2008).

The air flow pattern in the area is typically drainage flow winds in the early morning,

transition in the late morning to early afternoon, and upslope flow in the afternoon. That

is, due to the heating and cooling effects of the ground surface, the air flow pattern

generally exhibits a morning downslope to afternoon upslope cycle. This typical flow cycle

virtually traps the air pollutants in the valley. Transport of the air pollutants from the valley

to the mountain area can happen during the afternoon upslope flow hours, which is

normally about three hours before transition starts. After the transition, the air flow is

dominated by downslope flow, bringing the pollutants back to the valley. The average

annual wind speed is 6.2 miles per hour. 

Ozone Monitoring Network

The ozone monitoring network within the Maricopa eight-hour ozone nonattainment area

consists of 19 monitoring sites. The Tonto National Monument site is located just outside

the nonattainment area in Gila County and also monitors ozone. These stations are

currently operated by the Maricopa County Air Quality Department, the Pinal County Air

Quality Control District, and the Arizona Department of Environmental Quality. The ozone

monitoring sites are identified, along with summary data from 2005 through 2008, in

Tables 2-1 through 2-4. The geographical distribution of the ozone regional monitoring

network is shown in Figure 2-1.

Tables 2-1 through 2-4 show the four highest eight-hour ozone concentrations at each

monitor for the years 2005 through 2008, respectively. A violation of the standard occurs

when the fourth-highest value at each monitor, averaged over three consecutive years, is

0.085 ppm or higher. 

Historical Perspective

A review of the eight-hour ozone monitoring data reveals that there have been no violations

of the eight-hour ozone standard at any monitor in the Maricopa nonattainment area since

2004. In contrast to the past four years of “clean” data, there were seven violating monitors

in 2000. There was a noticeable decrease in the number of violations between 2000 and

2001, with only three violations recorded in 2001. During the years 2000 through 2008, the

annual number of ozone violations ranged from seven (in 2000) to zero (in 2005, 2006,

2007, and 2008). These data indicate that there has been an overall downward trend in

ozone concentrations in the nonattainment area over the last eight years. 
2-3

TABLE 2-1

2005 OZONE MONITORING DATA SUMMARY FOR

THE MARICOPA NONATTAINMENT AREA

(8-HOUR OZONE STANDARD: 0.08 PPM*)

Site

Max Value

(PPM)

2nd High

(PPM)

3rd High

(PPM)

4th High

(PPM)

Apache Junction Maint. Yard, 305 E. Superstition .076 .073 .070 .068

Blue Point, Usery Pass & Bush Highway .089 .088 .083 .081

Buckeye, 26453 W. MC 85S .067 .066 .066 .065

Cave Creek, 37019 N. Lava LaneS .084 .083 .083 .082

Central Phoenix, 1645 E. Roosevelt .081 .080 .078 .075

Dysart, 16825 N. DysartS .073 .069 .067 .066

Falcon Field, 4530 E. McKellipsS .081 .078 .078 .076

Fountain Hills, 16426 E. Palisades .096 .091 .088 .088

Glendale, 6000 W. OliveS .078 .077 .076 .076

Humboldt Mountain, Humboldt Mountain SummitS .088 .088 .087 .087

JLG Supersite, 4530 N. 17th Ave. .079 .077 .076 .076

North Phoenix, 601 E. Butler .089 .088 .085 .084

Pinnacle Peak, 25000 N. Windy Walk .085 .083 .083 .083

Rio Verde, 25608 N. Forest RoadS .093 .088 .087 .087

South Phoenix, 33 W. Tamarisk .081 .081 .076 .076

South Scottsdale, 2857 N. Miller .089 .084 .079 .077

Tempe, 1525 S. CollegeS .086 .078 .077 .076

Tonto National Monument, Tonto National ForestS .098 .097 .084 .084

West Chandler, 275 S. EllisS .082 .076 .075 .075

West Phoenix, 3847 W. Earll .072 .071 .069 .068

* Due to mathematical rounding, values $ 0.085 are necessary to exceed the standard. S Seasonal monitor operating from April 1 to November 1.

Source: Environmental Protection Agency Monitor Values Report.
2-4

TABLE 2-2

2006 OZONE MONITORING DATA SUMMARY FOR

THE MARICOPA NONATTAINMENT AREA

(8-HOUR OZONE STANDARD: 0.08 PPM*)

Site

Max Value

(PPM)

2nd High

(PPM)

3rd High

(PPM)

4th High

(PPM)

Apache Junction Maint. Yard, 305 E. Superstition .094 .090 .087 .084

Blue Point, Usery Pass & Bush Highway .064 .063 .062 .062

Buckeye, 26453 W. MC 85S .072 .068 .067 .067

Cave Creek, 37019 N. Lava LaneS .088 .083 .082 .080

Central Phoenix, 1645 E. Roosevelt .089 .083 .081 .080

Dysart, 16825 N. DysartS .079 .076 .075 .072

Falcon Field, 4530 E. McKellipsS .085 .082 .082 .079

Fountain Hills, 16426 E. Palisades .089 .086 .086 .084

Glendale, 6000 W. OliveS .084 .083 .079 .078

Humboldt Mountain, Humboldt Mountain SummitS .084 .084 .082 .079

JLG Supersite, 4530 N. 17th Ave. .085 .084 .083 .076

North Phoenix, 601 E. Butler .094 .087 .086 .085

Pinnacle Peak, 25000 N. Windy Walk .082 .079 .077 .076

Rio Verde, 25608 N. Forest RoadS .086 .084 .083 .083

South Phoenix, 33 W. Tamarisk .075 .072 .072 .069

South Scottsdale, 2857 N. Miller .086 .081 .080 .080

Tempe, 1525 S. CollegeS .087 .082 .081 .079

Tonto National Monument, Tonto National ForestS .089 .085 .081 .081

West Chandler, 275 S. EllisS .089 .089 .083 .081

West Phoenix, 3847 W. Earll .096 .088 .085 .082

* Due to mathematical rounding, values $ 0.085 are necessary to exceed the standard. S Seasonal monitor operating from April 1 to November 1.

Source: Environmental Protection Agency Monitor Values Report.
2-5

TABLE 2-3

2007 OZONE MONITORING DATA SUMMARY FOR

THE MARICOPA NONATTAINMENT AREA

(8-HOUR OZONE STANDARD: 0.08 PPM*)

Site

Max Value

(PPM)

2nd High

(PPM)

3rd High

(PPM)

4th High

(PPM)

Apache Junction Maint. Yard, 305 E. Superstition .083 .080 .079 .077

Blue Point, Usery Pass & Bush Highway .066 .066 .059 .058

Buckeye, 26453 W. MC 85S .066 .066 .064 .064

Cave Creek, 37019 N. Lava LaneS .083 .079 .079 .077

Central Phoenix, 1645 E. Roosevelt .073 .073 .070 .070

Dysart, 16825 N. DysartS .069 .069 .068 .065

Falcon Field, 4530 E. McKellipsS .080 .074 .074 .073

Fountain Hills, 16426 E. Palisades .083 .078 .074 .074

Glendale, 6000 W. OliveS .075 .075 .074 .071

Humboldt Mountain, Humboldt Mountain SummitS .080 .079 .079 .078

JLG Supersite, 4530 N. 17th Ave. .077 .076 .076 .076

North Phoenix, 601 E. Butler .081 .081 .080 .078

Pinnacle Peak, 25000 N. Windy Walk .076 .076 .075 .075

Rio Verde, 25608 N. Forest RoadS .082 .082 .080 .079

South Phoenix, 33 W. Tamarisk .079 .077 .073 .072

South Scottsdale, 2857 N. Miller .082 .077 .077 .077

Tempe, 1525 S. CollegeS .084 .077 .077 .076

Tonto National Monument, Tonto National ForestS .078 .076 .076 .076

West Chandler, 275 S. EllisS .084 .079 .074 .072

West Phoenix, 3847 W. Earll .079 .077 .076 .074

* Due to mathematical rounding, values $ 0.085 are necessary to exceed the standard. S Seasonal monitor operating from April 1 to November 1.

Source: Environmental Protection Agency Monitor Values Report.
2-6

TABLE 2-4

2008 OZONE MONITORING DATA SUMMARY FOR

THE MARICOPA NONATTAINMENT AREA+

(8-HOUR OZONE STANDARD: 0.08 PPM*)

Site

Max Value

(PPM)

2nd High

(PPM)

3rd High

(PPM)

4th High

(PPM)

Apache Junction Maint. Yard, 305 E. Superstition .082 .081 .081 .079

Blue Point, Usery Pass & Bush Highway .076 .075 .075 .074

Buckeye, 26453 W. MC 85S .071 .071 .070 .068

Cave Creek, 37019 N. Lava LaneS .080 .080 .080 .078

Central Phoenix, 1645 E. Roosevelt .078 .075 .072 .072

Dysart, 16825 N. DysartS .074 .067 .066 .066

Falcon Field, 4530 E. McKellipsS .079 .077 .077 .075

Fountain Hills, 16426 E. Palisades .080 .080 .080 .079

Glendale, 6000 W. OliveS .079 .077 .077 .074

Humboldt Mountain, Humboldt Mountain SummitS .080 .078 .078 .077

JLG Supersite, 4530 N. 17th Ave. .079 .079 .079 .078

North Phoenix, 601 E. Butler .083 .081 .081 .080

Pinnacle Peak, 25000 N. Windy Walk .080 .076 .073 .073

Rio Verde, 25608 N. Forest RoadS .081 .081 .079 .079

South Phoenix, 33 W. Tamarisk .079 .077 .076 .076

South Scottsdale, 2857 N. Miller .079 .078 .077 .076

Tempe, 1525 S. CollegeS .082 .082 .078 .078

Tonto National Monument, Tonto National ForestS .084 .082 .081 .078

West Chandler, 275 S. EllisS .079 .079 .077 .077

West Phoenix, 3847 W. Earll .081 .081 .080 .078

+ Preliminary data through September 30, 2008. Quality assurance of the data is in progress.

* Due to mathematical rounding, values $ 0.085 are necessary to exceed the standard. S Seasonal monitor operating from April 1 to November 1.

Sources: Environmental Protection Agency Air Quality System; Arizona Department of Environmental

Quality. 
!"a$

!"a$

!"c$

? ̧

Aß

Aß

Añ

Añ

Iv

Iv

?Â

Aÿ

!"`$

Añ

MAP AREA

Legend

Eight-Hour Ozone Nonattainment Area

Ozone Monitoring Sites

Existing Freeway

Planned Freeway

Major Roads

While every effort has been made to ensure the accuracy of this

information, the Maricopa Association of Governments makes no

warranty, expressed or implied, as to its accuracy and expressly

disclaims liability for the accuracy thereof.

g:/dev/maps/AQ/85x11/oz_mntrs.mxd

EIGHT-HOUR OZONE REGIONAL MONITORING

NETWORK

6 0 6 12

Miles

Prepared by the Maricopa Association of Governments, November 2008

Monitoring Site Name

AJ Apache Junction

BE Buckeye

BP Blue Point

CC Cave Creek

CP Central Phoenix

DY Dysart

FF Falcon Field

FH Fountain Hills

GL Glendale

HM Humboldt Mountain

NP North Phoenix

PP Pinnacle Peak

RV Rio Verde

SP South Phoenix

SS South Scottsdale

SUPR JLG Supersite

TE Tempe

TNM Tonto National Mon.

WC West Chandler

WP West Phoenix

Figure 2-1

BE

DY

GL

WP

SUPR

NP

CP

SP TE

SS

AJ

FF

BP

FH

RV PP

CC

HM

WC

TNM
2-8

Monitoring Results and Attainment of the Standard

The monitoring data presented in Table 2-5 verifies that the Maricopa nonattainment area

attained the national eight-hour ozone standard of 0.08 ppm for the last four years, in

accordance with the federal requirements of 40 CFR 50.10. For these years, data recovery

rates for the monitors within the ozone monitoring network exceeded the 75 percent

completeness requirements. In addition, all state and federal quality assurance procedures

have been followed. Figure 2-2 illustrates the highest three-year average of the

fourth-highest eight-hour ozone concentrations for monitors in the nonattainment area. In

general, peak ozone concentrations in the nonattainment area have exhibited a downward

trend over the last eight years. 

Quality Assurance Program

Eight-hour ozone monitoring data for the Maricopa nonattainment area has been collected

and quality-assured in accordance with 40 CFR, Part 58, Appendix A “Quality Assurance

Requirements for SLAMS, SPMs, and PSD Air Monitoring” and EPA’s “Quality Assurance

Handbook for Air Pollution Measurement Systems, Volume II; Ambient Air Quality

Monitoring Program”. The data are recorded in the EPA Air Quality System and are

available for public review through sources such as the EPA AirData website and air quality

monitoring reports produced annually by the Maricopa County Air Quality Department and

the Arizona Department of Environmental Quality.

APPROVAL OF THE OZONE NONATTAINMENT SIP ELEMENT FOR THE MARICOPA

AREA

MAG submitted the Eight-Hour Ozone Plan for the Maricopa Nonattainment Area to EPA

by June 15, 2007, as required by the Clean Air Act. In accordance with Section 110 of the

Clean Air Act, a completeness finding on this Plan was deemed by operation of law, since

a determination was not made by EPA within six months of receipt of the Plan.

The Eight-Hour Ozone Plan has not been approved by EPA under Section 110(k) of the

Clean Air Act. However, approval of both the eight-hour ozone attainment and

maintenance plans may occur concurrently with EPA’s action to redesignate the area to

attainment.

IMPROVEMENT IN AIR QUALITY DUE TO PERMANENT AND ENFORCEABLE

EMISSION REDUCTIONS

According to the EPA memorandum, Procedures for Processing Requests to Redesignate

Areas to Attainment, September 4, 1992, “The state must be able to reasonably attribute

the improvement in air quality to emission reductions which are permanent and

enforceable.” This section is intended to demonstrate that the improved air quality in the

Maricopa County nonattainment area has occurred as a result of permanent and

enforceable emission reductions. 
2-9

TABLE 2-5

EIGHT-HOUR OZONE MONITORING DATA SUMMARY

THREE-YEAR AVERAGE OF THE FOURTH-HIGH, 2005-2008+

(8-HOUR OZONE STANDARD: 0.08 PPM*)

Site

2003-2005

Avg. 4th

High (PPM)

2004-2006

Avg. 4th

High (PPM)

2005-2007

Avg. 4th

High (PPM)

2006-2008

Avg. 4th

High (PPM)+

Apache Junction .069 .073 .076 .080

Blue Point .080 .072 .067 .064

BuckeyeS N/A .063 .065 .066

Cave CreekS .080 .079 .079 .078

Central Phoenix .076 .076 .075 .074

DysartS .068 .067 .067 .067

Falcon FieldS .075 .075 .076 .075

Fountain Hills .082 .082 .082 .079

GlendaleS .079 .076 .075 .074

Humboldt MountainS .084 .081 .081 .078

JLG Supersite .074 .074 .076 .076

North Phoenix .083 .083 .082 .081

Pinnacle Peak .078 .075 .078 .074

Rio VerdeS .081 .081 .083 .080

South Phoenix .074 .072 .072 .072

South Scottsdale .076 .076 .078 .077

TempeS .075 .075 .077 .077

Tonto National MonumentS .081 .080 .080 .078

West ChandlerS .074 .075 .076 .076

West Phoenix .072 .074 .074 .078

+ Preliminary data through September 30, 2008. Quality assurance of the data is in

progress.

* Due to mathematical rounding, values $ .085 ppm are necessary to exceed the

standard.

S Seasonal monitor operating from April 1 to November 1.

N/A-Data not available.

Sources: Environmental Protection Agency Air Quality System and Monitor Values

Report; Arizona Department of Environmental Quality.
2-10

FIGURE 2-2

EIGHT-HOUR OZONE TRENDS

(2000-2008)

* Due to mathematical rounding, values $ .085 ppm are necessary to exceed the standard. + Preliminary data through September 30, 2008. Quality assurance of the data is in progress.

Monitors Where the Highest 3-Year Average of the 4th-Highest

8-Hour Ozone Concentration Occurred

(HM) Humboldt Mountain

(MO) Mount Ord

(NP) North Phoenix

(PP) Pinnacle Peak

(RV) Rio Verde

Sources: Environmental Protection Agency Air Quality System and Monitor Values Report; Arizona

Department of Environmental Quality.
2-11

As Figure 2-2 illustrates, there has been a general downward trend in ozone concentrations

at monitors in the nonattainment area since 2000. The fourth-highest ozone levels

decreased by about five percent between 2003 and 2008, at the same time population,

employment and vehicle travel in the nonattainment area increased by more than fifteen

percent.

Over time, numerous control measures have been implemented in the Maricopa area that

have resulted in the decline in ozone concentrations. For example, the Environmental

Protection Agency published a final rule on May 27, 1998 determining that the Maricopa

nonattainment area has in place sufficient control measures to meet the 15 percent rate of

progress requirement in the Clean Air Act. The Final Serious Area Ozone State

Implementation Plan submitted in December 2000 also included Reasonably Available

Control Technology (RACT) requirements for sources subject to RACT under the Clean Air

Act. In addition, the Serious Area Carbon Monoxide Plan and Carbon Monoxide

Redesignation Request and Maintenance Plan include measures which have reduced

ozone. 

The Eight-Hour Ozone Plan demonstrated, through modeling and supporting technical

analyses, that the standard would be attained by June 15, 2009 (MAG, 2007). The ozone

monitoring data shown earlier in this Chapter indicates that the nonattainment area has not

violated the standard since 2004. 

The general approach in the Eight Hour Ozone Maintenance Plan is to demonstrate

maintenance of the eight-hour ozone standard through 2025 using emission reduction

credit for committed measures in the Eight-Hour Ozone Plan. Four of these measures,

Summer Fuel Reformulation, Phased-In Emission Test Cutpoints, One-Time Waiver from

Vehicle Emissions Test, and Tougher Enforcement of Vehicle Registration and Emission

Test Compliance, were approved by EPA in prior plans and programs. Numeric credit is

also taken in the Maintenance Plan for Federal Nonroad Equipment Emissions Standards

and Expansion of Area A Boundaries (HB 2538), which were committed contingency

measures in the Eight-Hour Ozone Plan. A seventh maintenance measure, Ban Open

Burning During Ozone Season, is a new ozone measure passed by the Arizona Legislature

in June 2007.

The Maintenance Plan in Chapter Three documents, through modeling and supporting

technical analyses, that the eight-hour ozone standard will continue to be maintained

through 2025, despite substantial growth in population, employment and vehicle miles of

travel expected between the baseline year of 2005 and the maintenance year of 2025. The

impact of this growth on ozone precursor emissions will be offset by more stringent federal

emission standards for light duty vehicles and nonroad equipment, as well as the

committed State, County, and local measures in previously-approved plans. 

The next section describes the committed measures that were used for numeric credit in

modeling maintenance of the eight-hour ozone standard in 2025.
2-12

COMMITTED MEASURES USED FOR NUMERIC CREDIT IN THE MAINTENANCE

DEMONSTRATION

The seven committed measures used for numeric credit in the modeling for the

Maintenance Plan are described below. Table 3-2 in Chapter Three summarizes the

emission reductions attributable to each of these committed maintenance measures in

2025. Additional details on the methodologies used to quantify the emission reduction

credit for each measure are provided in Section IV-7-1 of the Technical Support Document

for the Eight-Hour Ozone Redesignation Request and Maintenance Plan (TSD). 

The following committed measures, which are permanent and enforceable, are anticipated

to be in place through the maintenance year of 2025. Continued implementation of these

measures, as well as the other committed measures in the aforementioned plans, will

ensure that the ozone standard is met through 2025.

1. Summer Fuel Reformulation: California Phase 2 and Federal Phase II Reformulated

Gasoline with 7 psi from May 1 through September 30 

The Arizona Legislature passed H.B. 2307 in 1997 which contains requirements for the sale

of gasoline from and after May 1, 1999 in Area A, subject to an appropriate waiver granted

under Section 211 (c) (4) of the Clean Air Act, that meets the following fuel reformulation

options:

• California Phase 2 Reformulated Gasoline, including alternative formulations

allowed by the predictive model, as adopted by the California Air Resources Board

pursuant to the California Code of Regulations, Title 13, Sections 2261 through

2262.7 and 2265, in effect on January 1, 1997, that meets the maximum 7.0 psi

summertime vapor pressure requirements in A.R.S. Section 41-2083, Subsections

D and F.

• Gasoline that meets the standards for Federal Phase II Reformulated Gasoline,

as provided in 40 CFR Section 80.41, paragraphs (a) through (h), in effect on

January 1, 1997, that meets the maximum 7.0 psi summertime vapor pressure

requirement in A.R.S. Section 41-2083 Subsections D and F.

On February 10, 1998, the Environmental Protection Agency approved Arizona’s cleaner

burning gasoline (CBG) program into the State Implementation Plan. The program was

implemented in two stages - from June to September 1998, gasoline sold in the area had

to meet the standards similar to Federal Phase I Reformulated Gasoline or California’s

Phase 2 Reformulated Gasoline. Then, beginning May 1, 1999, all gas sold in the area had

to meet standards similar to Federal Phase II or California’s Phase 2 Reformulated

Gasoline.
2-13

Arizona’s CBG Program was included in the 1998 metropolitan Phoenix Ozone 15 Percent

Rate of Progress Federal Implementation Plan as a committed control measure for

emissions reduction credit. On July 6, 1999, EPA finalized a rule revising the federal plan

as it related to the CBG Program.

On April 28, 2000, Senate Bill 1504 was signed into law by the Governor of Arizona. The

law revised A.R.S. Section 41-2124 by eliminating the minimum oxygenate requirement for

summertime gasoline in Maricopa County. Because of the cost and difficulty of blending

ethanol in CBG and meeting the 7.0 psi Reid Vapor Pressure standard, methyl tertiary butyl

ether (MTBE) had been the primary oxygenate used in Arizona’s summertime CBG. In

addition, A.R.S. Section 41-2122. E. prohibited the use of MTBE in gasoline beginning on

January 1, 2005.

On September 29, 2003, the Environmental Protection Agency published a notice

proposing to approve revisions to the Arizona Clean Burning Gasoline Program currently

approved in the State Implementation Plan. The revisions replace Arizona’s interim CBG

program with a permanent program, amend the wintertime CBG program to limit the types

of gasoline that may be supplied, and remove the minimum oxygen requirement for

summertime gasoline. On January 26, 2004, the EPA Administrator signed the final

approval notice for the revisions to the Arizona Clean Burning Gasoline Program. The final

notice was published in the Federal Register on March 4, 2004, effective on April 5, 2004.

This measure is a committed measure in the Serious Area Ozone SIP, the One-Hour

Ozone Maintenance Plan, and the Eight-Hour Ozone Plan. In the Eight-Hour Ozone

Maintenance Plan, this measure reduces anthropogenic VOC emissions by 0.5 percent and

increases anthropogenic NOx emissions by 0.1 percent in 2025. 

2. Phased-In Emission Test Cutpoints

The Arizona Vehicle Inspection Maintenance Program was established in 1976 to promote

the clean operation of motor vehicles by controlling vehicle exhaust emissions. The

program is operated by the Arizona Department of Environmental Quality and contains the

provisions listed in Section 182(c)(3) of the Clean Air Act for an Enhanced Vehicle

Inspection and Maintenance Program. 

The Vehicle Emissions Inspection Maintenance Program was significantly enhanced and

strengthened by the Arizona Legislature in 1993 (H.B. 2001). The Legislature established

a biennial, transient loaded (I/M 240) emissions test for gasoline powered vehicles model

year 1981 or newer with a gross vehicle weight of up to 8,500 pounds, beginning

January 1, 1995. 

In 1993, the Arizona Legislature passed H.B. 2001 which increased the repair threshold

limits for gasoline powered vehicles in order to be eligible for a waiver through the Vehicle

Emissions Inspection Maintenance Program. The repair limits were increased in the

following manner: 1967-1974 from $50 to $100; 1975-1980 from $200 to $300; and 1981
2-14

and newer from $300 to $450. The bill also increased the repair threshold limits from $300

to $500 for diesel powered vehicles with tandem axles or a gross vehicle weight in excess

of 26,000 pounds.

The Arizona Legislature passed H.B. 2237 in 1997 which contained an appropriation of

$120,000 from the State General Fund to the Arizona Department of Environmental Quality

to develop and implement an alternative test protocol to reduce the false failure rates

associated with the more stringent pass-fail standards for the Vehicle Emissions Testing

Program (Section 19 of H.B. 2237).

In addition, the Arizona Department of Environmental Quality was to implement Interim

Test Cutpoints for the Vehicle Emissions Inspection Program until issues were resolved

with the final test cutpoints for the I/M 240 Program. The Interim Cutpoints were selected

to achieve the following failure rates in three vehicle class categories (Light Duty Gasoline

Vehicles, Light Duty Gasoline Trucks 1, and Light Duty Gasoline Trucks 2: 50 percent for

Model Years 1981-85; 25 percent for 1986 to 1989 model years, and 10 percent for Model

Years 1990-93). 

In August 2002, EPA proposed approval of the Arizona I/M Program and signed the final

approval notice on October 31, 2002. The final approval notice was published in the

Federal Register on January 22, 2003. 

This measure is a committed measure in the Serious Area Carbon Monoxide Plan, the

Carbon Monoxide Maintenance Plan, the One-Hour Ozone Maintenance Plan, and the

Eight-Hour Ozone Plan. In the Eight-Hour Ozone Maintenance Plan, this measure reduces

anthropogenic VOC and NOx emissions by less than 0.1 percent in 2025. 

3. One-Time Waiver from Vehicle Emissions Test

The Arizona Legislature passed S.B. 1002 in 1996 which limits the issuance of a waiver for

failure to comply with the emission testing requirements to one-time only beginning January

1, 1997 (A.R.S. 49-542 D). This measure is a committed measure in the Serious Area

Carbon Monoxide Plan, the Carbon Monoxide Maintenance Plan, the One-Hour Ozone

Maintenance Plan, and the Eight-Hour Ozone Plan. In the Eight-Hour Ozone Maintenance

plan, this measure reduces anthropogenic VOC emissions by less than 0.1 percent and

anthropogenic NOx emissions by 0.1 percent in 2025. 

4. Tougher Enforcement of Vehicle Registration and Emissions Test Compliance

The Motor Vehicle Division (MVD) of the Arizona Department of Transportation (ADOT) has

instituted a comprehensive vehicle registration enforcement program. Three key elements

of the new program are a Registration Enforcement Team, a Registration Enforcement

Tracking System, and a New Resident Tracking Program. Through public participation,

consistent policy and procedure application, and new tracking methods, MVD will enforce

the Arizona registration laws to ensure vehicles in question are registered properly. This
2-15

will be an ongoing effort.

Another phase of the Program is an initiative to coordinate ADOT efforts with other law

enforcement agencies to assist MVD personnel in enforcing registration compliance. Other

initiatives include a system user agreement between MVD and the City Courts to utilize

information in conjunction with registration compliance and discussions with U.S. West

(now known as Qwest) for obtaining information relating to new connect customers.

The Arizona Legislature passed S.B. 1427 in 1998 which requires school districts and

special districts in Area A to prohibit parking in employee parking lots by employees who

have not complied with emissions testing requirements. Cities, towns, and counties in Area

A and Area B are currently subject to this provision (A.R.S. 49-552).

In 1999, the Arizona Legislature passed H.B. 2254 which requires each vehicle that is

owned by the United States government and that is domiciled in this state for more than

ninety consecutive days and each vehicle that is owned by a state or political subdivision

of this state to comply with A.R.S. 49-542. 

Collectively, the provisions in H.B. 2254 that apply to Tougher Enforcement of Vehicle

Registration and Emissions Test Compliance include A.R.S. 49-557 and 49-541.01 D.

and E.

This measure is a committed measure in the Serious Area Carbon Monoxide Plan, the

Carbon Monoxide Maintenance Plan, the One-Hour Ozone Maintenance Plan, and the

Eight-Hour Ozone Plan. In the Eight-Hour Ozone Maintenance Plan, this measure reduces

anthropogenic VOC emissions by less than 0.1 percent and anthropogenic NOx emissions

by 0.1 percent in 2025. 

5. Federal Nonroad Equipment Emissions Standards

In 1998, EPA issued a final rule setting more stringent Tier 2 and Tier 3 emission standards

for new diesel nonroad equipment (EPA, 1998). The Tier 2 program phased in more

stringent standards for all equipment types between 2001 and 2006. The Tier 3 program

imposed even more stringent standards for 50 to 750 horsepower (hp) engines, beginning

in 2005 through 2008. 

In 2004, EPA issued the Clean Air Diesel - Tier 4 Final Rule that requires manufacturers

to produce nonroad engines with advanced emission-control technologies that will reduce

emissions by an additional 90 percent or more (EPA, 2004). The Tier 4 standards apply

to nonroad engines with less than 25 hp, beginning in 2008. The Tier 4 standards for larger

engines will be phased in between 2011 and 2015, depending upon the size and type of

engine. 

This measure was a committed contingency measure in the Eight-Hour Ozone Plan. In the

Eight-Hour Ozone Maintenance Plan, this federally-mandated measure is expected to
2-16

reduce anthropogenic VOC emissions by 7.9 percent and anthropogenic NOx emissions

by 16.5 percent in 2025. 

6. Expansion of Area A Boundaries (HB 2538)

The Arizona Legislature passed H.B. 2538 in 2001 which expands the boundaries of Area

A. Previously, the Area A boundaries followed the boundaries defined by S.B. 1427, which

was passed by the Arizona Legislature in 1998. Specifically, H.B. 2538 expands the

boundaries of Area A past those described in S.B. 1427, adding additional portions of

Maricopa County west of Goodyear and Peoria and a small piece of land on the north side

of Lake Pleasant. The implementation of air quality measures in the areas described in

H.B. 2538 began on January 1, 2002, except for public sector alternative fuel requirements

that are phased in over a seven year period.

“Area A” means the area delineated as follows:

(a) In Maricopa County:

Township 8 North, Range 2 East and Range 3 East

Township 7 North, Range 2 West Through Range 5 East

Township 6 North, Range 5 West Through Range 6 East

Township 5 North, Range 5 West Through Range 7 East

Township 4 North, Range 5 West Through Range 8 East

Township 3 North, Range 5 West Through Range 8 East

Township 2 North, Range 5 West Through Range 8 East

Township 1 North, Range 5 West Through Range 7 East

Township 1 South, Range 5 West Through Range 7 East

Township 2 South, Range 5 West Through Range 7 East

Township 3 South, Range 5 West Through Range 1 East

Township 4 South, Range 5 West Through Range 1 East

(b) In Pinal County:

Township 1 North, Range 8 East And Range 9 East

Township 1 South, Range 8 East And Range 9 East

Township 2 South, Range 8 East And Range 9 East

Township 3 South, Range 7 East Through Range 9 East

(c) In Yavapai County:

Township 7 North, Range 1 East And Range 1 West Through Range 2 West

Township 6 North, Range 1 East And Range 1 West

It is important to note that under A.R.S. 49-406 (A), MAG has statutory authority to conduct

nonattainment area planning within Maricopa County. However, MAG does not have air

quality planning authority for either Pinal or Yavapai Counties.

Under A.R.S. 49-406 (K), the Arizona Department of Environmental Quality has air quality
2-17

planning authority to adopt SIP measures in those portions of Area A in Pinal and Yavapai

Counties where MAG does not have authority. For ozone, the committed measures include

the Vehicle Emissions Inspection Program, Clean Burning Gasoline Program, Stage II

Vapor Recovery Program, Trip Reduction Program, Voluntary Vehicle Repair and Retrofit

Program, and Traffic Signal Synchronization. For carbon monoxide, the committed

measures include the Vehicle Emissions Inspection Program, Clean Burning Gasoline

Program, Trip Reduction Program, Clean Burning Fireplace Construction and Conversion

Program, No Burn Days and Public Participation Programs, and Voluntary Vehicle Repair

and Retrofit Program. MAG anticipates that ADEQ will also provide notice and public

hearing on this plan, perhaps jointly with MAG, prior to ADEQ’s adoption of the plan under

A.R.S section 49-404 and ADEQ's subsequent submittal of the plan to EPA for approval.

Emission reduction credit for this measure applies only to the area between the Area A

boundary established by S.B. 1427 and the Area A boundary established by H.B. 2538. 

The Area A boundaries defined by H.B. 2538 are shown in Figure 1-1. The expansion of

Area A by H.B. 2538 was a contingency measure in the Eight-Hour Ozone Plan. In the

Eight-Hour Ozone Maintenance Plan, this measure reduces anthropogenic VOC emissions

by less than 0.1 percent and anthropogenic NOx emissions by 0.1 percent in 2025.

7. Ban on Open Burning During the Ozone Season

This new ozone measure was passed by the Arizona Legislature in June 2007 as part of

S.B. 1552. S.B 1552 states that “from May 1 to September 1 each year, it is unlawful for

any person to ignite, cause to be ignited, permit to be ignited or suffer, allow or maintain

any open outdoor fire in Area A as defined in Section 49-541". Credit for this measure was

not included in the Eight-Hour Ozone Plan, since S.B. 1552 was passed by the Legislature

and signed into law after the modeling and documentation of the Eight-Hour Ozone Plan

were completed and the plan had been submitted to EPA by the federal deadline of June

15, 2007. In the Eight-Hour Ozone Maintenance Plan, this measure reduces anthropogenic

VOC and NOx emissions by less than 0.1 percent in 2025.

CLEAN AIR ACT SECTION 110 AND PART D REQUIREMENTS

Before an area can be redesignated to attainment, requirements of Section 110 and Part

D of the Clean Air Act must be met. The provisions of Section 110(a)(2) and Part D are

required as part of the State Implementation Plan to bring the Maricopa County

nonattainment area into attainment, and have been addressed in plans already approved

by EPA. By approving these prior plans, EPA has determined that all applicable provisions

of Section 110 and Part D have been met. This section summarizes the applicable

requirements of Section 110 and Part D and provides references from the previouslyapproved plans that address these requirements.

Section 110(a)(2) addresses general requirements for a State Implementation Plan (SIP).

The Eight-Hour Ozone Redesignation Request and Maintenance Plan for the Maricopa

Nonattainment Area will be a revision to the Arizona SIP.
2-18

A. Include enforceable measures and schedules necessary to show compliance (1)

B. Monitor and compile data on ambient air quality (2)

C. Provide a program to enforce measures in (A) and regulate stationary sources

(1),(4)

D. Prohibit sources from emitting pollutants that would contribute significantly to

nonattainment, interfere with maintenance of the standard, or interfere with

Prevention of Significant Deterioration (PSD) or visibility in other states (3)

E. Provide assurances that there are adequate resources to implement the plan,

nothing in the SIP is otherwise prohibited by law, and the State has responsibility for

ensuring adequate implementation (1)

F. Stationary source emissions monitoring and reporting (4)

G. Provide for emergency powers authority (5)

H. Provide for the revisions to the plan (6)

I. Meet the applicable requirements of Part D for nonattainment areas (10)

J. Meet the requirements of Section 121 (consultation) (9); Section 127 (public

notification) (7), and part C (PSD and visibility) (3),(4)

K. Perform air quality modeling (8)

L. Permitting fees for major stationary sources (4)

M. Consultation and participation by local political subdivisions affected by the SIP (9)

The numbers following each SIP requirement listed above refer to the subsection below

that describes how the requirements of Section 110(a)(2) are met by this Plan.

(1) Enforcement, Adequate Resources, and Responsibility for Adequate Implementation

The Eight-Hour Ozone Redesignation Request and Maintenance Plan relies on State,

County and local commitments to implement control measures in the Serious Area Carbon

Monoxide Plan (MAG, 2001), the One-Hour Ozone Maintenance Plan (MAG, 2004), and

the Serious Area Ozone SIP (ADEQ, 2000). All of these plans have been approved by

EPA. Sections 110(a)(2)(A),(C), and (E), concerning plan enforcement and implementation

requirements, are addressed in Chapter Eight (page 8-146) and Chapter Eleven (page 11-

1) of the Serious Area Carbon Monoxide Plan. In order to comply with these sections, a

State law was passed in 1992 which provides an approach for assurances that State and

local committed measures will be adequately implemented (A.R.S. Section 49-406 I. and

J.).

Regarding committed measures, A.R.S. Section 49-406 G. (passed by the Legislature in

1992) requires that each agency which commits to implement any control measure

contained in the State 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
2-19

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.

Chapter Eleven of the Serious Area Carbon Monoxide Plan includes resolutions from the

MAG member agencies and other implementing entities. The resolutions indicate specific

commitments to implement various control strategies. Generally, the authorities of cities

and towns to implement the types of measures that they have committed to in their

respective resolutions are provided under A.R.S. § 9-240 Powers of Common Council. The

general authorities of the County to implement the measures in the commitments are

provided under A.R.S. § 11-251 and A.R.S. § 49-478. Copies of these local and county

government authorities are included in Chapter Eleven of the Revised Serious Area Carbon

Monoxide Plan.

If any person (includes State, County, local governments, regional agencies, and other

entities) fails to implement a committed measure, 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 committed measure or if the County fails to backstop the local

governments and regional agencies (see Appendix C, Exhibit 2, Serious Area Carbon

Monoxide Plan).

(2) Monitoring and Compiling of Data on Ambient Air Quality

Section 110(a)(2)(B) establishes the requirement to monitor, compile, and analyze ambient

air quality data. Appendix A, Exhibit 2 of the Serious Area Carbon Monoxide Plan contains

the 1992 Memorandum of Agreement for Air Quality Planning (MAG, 2001). This

agreement identifies Maricopa County and the Arizona Department of Environmental

Quality as having the primary roles for air quality monitoring, including special purpose air

quality and meteorological monitoring for plan development.

Chapter Four of the Serious Area Carbon Monoxide Plan (page 4-5) provides additional

evidence that the monitoring requirements for the region are being met through the efforts

of Maricopa County and the Arizona Department of Environmental Quality. Arizona

Statutes 49-406. Nonattainment area plan and 49-424. Duties of Department provide the

regulatory basis for air quality monitoring in the State and any nonattainment areas.

Additional information on the quality assurance program for the ozone monitoring network

operated in the Maricopa nonattainment area is provided below.

Eight-hour ozone monitoring data for the Maricopa nonattainment area has been collected

and quality-assured in accordance with 40 CFR, Part 58, Appendix A “Quality Assurance

Requirements for SLAMS, SPMs, and PSD Air Monitoring” and EPA’s “Quality Assurance

Handbook for Air Pollution Measurement Systems, Volume II; Ambient Air Quality

Monitoring Program”. The data are recorded in the EPA Air Quality System and are

available for public review through sources such as the EPA AirData website and air quality

monitoring reports produced annually by the Maricopa County Air Quality Department and
2-20

the Arizona Department of Environmental Quality.

(3) Provisions to Prohibit Sources from Impacting Air Quality in Other States

Section 110(a)(2)(D) requires that a SIP contain adequate provisions prohibiting any source

or other type of emissions activity within the State from emitting any air pollutant in amounts

which will contribute significantly to nonattainment in, or interfere with maintenance by, any

other State with respect to any such national primary or secondary ambient air quality

standard; or interfere with measures required to be included in the applicable

implementation plan for any other State under Part C to prevent significant deterioration of

air quality or to protect visibility.

Visibility, as defined in Part C of the Clean Air Act, is currently addressed through a Federal

Implementation Plan for the State of Arizona. The lack of proximity to another state makes

it unlikely that ozone emissions are transported from the Maricopa nonattainment area to

another state. 

(4) Preconstruction Review for All New and Modified Stationary Sources; Stationary

Source Emissions Monitoring; and Permitting Fees for Major Stationary Sources

The requirements of Sections 110(a)(2)(C), (F), and (L), concerning preconstruction review,

emissions monitoring, and permitting fees for stationary sources, are addressed by the

State in Title 49. Article 2. State Air Pollution Control, and Article 3. County Air Pollution

Control, of the Arizona Revised Statutes. Compliance with this requirement is the

responsibility of the Arizona Department of Environmental Quality or applicable county

agency. Appendix A, Exhibit 2 of the Serious Area Carbon Monoxide Plan contains the

1992 Memorandum of Agreement for Air Quality Planning (MAG, 2001). This agreement

identifies Maricopa County as having the lead role for stationary source emissions control.

Following adoption by the State, Maricopa County adopted new source review regulations

designed to prevent significant deterioration of air quality, patterned after the State

regulations. The Maricopa County Regulations contain requirements for obtaining

installation permits for new major sources located in nonattainment, attainment, or

unclassifiable areas. Both the State and Maricopa County new source review regulations

are currently in effect.

The Maricopa County Air Pollution Control Regulations contain the regulations that

constitute the legal basis for control of air pollution sources in Maricopa County, Arizona.

They are adopted to implement the policy set forth in Title 49 of the Arizona Revised

Statutes and to fulfill the State’s responsibilities under the federal Clean Air Act and its

amendments to provide a legally enforceable State Implementation Plan for the attainment

and maintenance of the National Ambient Air Quality Standards.

Applicable Maricopa County Air Pollution Control Regulations include; Rule 240 - Permits

for New Major Sources and Major Modifications to Existing Major Sources, Rule 241 -
2-21

Permits for New Sources and Modifications to Existing Major Sources, and Rule 245 -

Continuous Source Emission Monitoring.

(5) Provide for Authority Comparable to that in Section 303 for Emergency Powers

Section 110(a)(2)(G) addresses the authority for emergency powers. Under Section 303

of the Clean Air Act, upon receipt of evidence that a pollution source or combination of

sources (including moving sources) is presenting an imminent and substantial

endangerment to public health or welfare, or the environment, the EPA Administrator may

bring suit on behalf of the United States in the appropriate United States district court to

immediately restrain any person causing or contributing to the alleged pollution to stop the

emission of air pollutants causing or contributing to such pollution or to take such other

action as may be necessary. If it is not practicable to assure prompt protection of public

health or welfare or the environment by commencement of such a civil action, the

Administrator may issue such orders as may be necessary to protect public health or

welfare or the environment.

Emergency powers for the State of Arizona are addressed under A.R.S. 49-465. Imminent

and substantial endangerment; 49-462.07 Violation; injunctive relief; and 49-465. Air

Pollution Emergency.

(6) Provide for Plan Revisions to Account for Changes to the NAAQS or When a Plan

is Found Substantially Inadequate to Attain a Standard

Section 110(a)(2)(H) requires a plan revision to take into account revisions of such national

primary or secondary ambient air quality standard, or the availability of improved or more

expeditious methods of attaining such standard, and whenever the Administrator finds that

the plan is substantially inadequate to attain the national ambient air quality standard. 

A.R.S. 49-404. State Implementation Plan and 49-406. Nonattainment Area Plan provisions

provide for State, county, and local agencies to revise the SIP to account for changes to

air quality standards or if a plan is found to be inadequate. The applicable documentation

for making plan revisions can be found in the Serious Area Carbon Monoxide Plan,

Appendix A, Exhibit 2, 1992 Memorandum of Agreement for Air Quality Planning (MAG,

2001).

(7) Meet the Applicable Requirements of Section 127 (Relating to Public Notification)

Section 110(a)(2)(J) requires a plan revision to meet the applicable requirements of Section

127 relating to Public Notification. Public notification procedures followed for the Serious

Area Carbon Monoxide Plan are documented in the section, Public Participation in the

Preparation of the MAG 1999 Serious Area Carbon Monoxide Plan on page 10-3 (MAG,

2001).
2-22

(8) Air Quality Modeling

Section 110(a)(2)(K) provides for the performance of such air quality modeling as the

Administrator may prescribe for the purpose of predicting the effect on ambient air quality

of any emissions of any air pollutant for which the Administrator has established a national

ambient air quality standard, and the submission, upon request, of data related to such air

quality modeling to the Administrator. 

In the Eight-Hour Ozone Plan, MAG performed air quality modeling with EPA-approved

models to demonstrate attainment of the standard by June 15, 2009 (MAG, 2007). The

modeling and supplemental analyses that support the modeling results are described in the

Technical Support Document in Appendix A, Exhibit 2, of the 2007 Eight-Hour Ozone Plan.

The Modeling Protocol in Support of an Eight-Hour Ozone Redesignation Request and

Maintenance Plan describes the modeling to be performed for the maintenance

demonstration. For details, see Appendix I-i of the Technical Support Document for Ozone

Modeling in Support of the Eight-Hour Ozone Redesignation Request and Maintenance

Plan for the Maricopa Nonattainment Area (TSD).

Chapter Three of this Plan describes the air quality modeling for the 2025 maintenance

demonstration. Section IV of the TSD identifies the key inputs to the ozone modeling,

including methods and assumptions used to develop the baseline and future year emission

inventories and quantify the emission reduction credit for the maintenance measures.

Section V of the TSD provides the results of the photochemical grid modeling and the

unmonitored area analysis, both of which support the finding that the eight-hour ozone

standard will continue to be attained through 2025. 

(9) Consultation and Participation by Local Political Subdivisions Affected by the SIP

Evidence for consultation and participation by local political subdivisions affected by the SIP

can be found in Chapter Ten, Public Participation in the Serious Area Carbon Monoxide

Plan on page 10-1 (MAG, 2001). The decision-making structure of the Maricopa

Association of Governments includes twenty-five cities and towns; the Fort McDowell, Salt

River Pima-Maricopa, and Gila River Indian Communities, Maricopa County, and the

Arizona Department of Transportation. 

Appendix A, Exhibit 2 -1992 Memorandum of Agreement for Air Quality Planning, in the

Serious Area Carbon Monoxide Plan details the consultation and participation process used

in developing the air quality plans.

(10) Meet the Applicable Requirements of Part D

Part D, Subpart 1, Section 172, of the Clean Air Act specifies the Nonattainment Plan

provisions applicable to the Eight-Hour Ozone Redesignation Request and Maintenance

Plan. The Plan meets each of the provisions as discussed below.
2-23

A. Implement all reasonably available control measures as expeditiously as practicable

In accordance with Section 172(c)(1), the state is required to submit a revision that

implements reasonably available control measures (RACM) as expeditiously as practicable,

including such reductions as may be obtained through the adoption, at a minimum, of

RACT. Since the Maricopa nonattainment area is designated as a subpart 1 area for

ozone, and demonstrates attainment by July 15, 2009, RACT is deemed to be met with

control requirements associated with a demonstration that the NAAQS is attained as

expeditiously as practicable (70FR71612, 11/29/2005, Section IV.G.1). Under the antibacksliding provisions of 40 CFR 51.905 for areas designated Serious nonattainment for

the one-hour ozone standard at the time of designation for the eight-hour standard, the

state remained subject to the obligations to implement RACT for the categories of sources

identified under Sections 182(a)(2)(A) and (b)(2). On June 14, 2005, EPA approved the

One-Hour Ozone Redesignation Request and Maintenance Plan for the Maricopa County

Nonattainment Area, including the RACT demonstration under Sections 182(a)(2)(A) and

(b)(2) (MAG, 2004). NOx RACT was not required in the One-Hour Ozone Maintenance

Plan, because EPA approved a NOx exemption petition for the nonattainment area on April

19, 1995. The source categories subject to RACT, in accordance with Section 172(c)(1)

and 40 CFR 51.905, are summarized in Table 2-6.

B. Plans shall require reasonable further progress

In Part D of the Clean Air Act, Section 171 indicates that the term “Reasonable Further

Progress” means such “annual incremental reductions in emissions of the relevant air

pollutant as are required by this part or may reasonably be required by the Administrator

for the purpose of ensuring attainment of the applicable national ambient air quality

standard by the applicable date.” Reasonable further progress is addressed in Chapter

Five of the Eight-Hour Ozone Plan (MAG, 2007).

C. Plans shall include a comprehensive, accurate, current inventory of actual emissions

from all sources of the relevant pollutant or pollutants in the area and periodic

revisions

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

emissions from all sources. On April 1, 1993, the 1990 base year emission inventory for

the Maricopa County ozone nonattainment area was submitted to EPA. Full approval of

the 1990 inventory was effective on June 26, 1998. The 1996 base year ozone inventory

was submitted as part of the Final Serious Area Ozone SIP in Appendix E. 

The 1999 Periodic Ozone Emissions Inventory for the Maricopa County Nonattainment

Area was included in the One-Hour Ozone Redesignation Request and Maintenance Plan

as Appendix A, Exhibit 1. The 1999 inventory was submitted to EPA in August 2002. 

The 2002 Periodic Emissions Inventory of Ozone Precursors for the Maricopa County,

Arizona, Nonattainment Area was included in Appendix A, Exhibit 1, of the Eight-Hour 
2-24

TABLE 2-6

MARICOPA COUNTY VOC RACT RULES AND SIP STATUS

CONTROL TECHNIQUES GUIDELINES

Rule Adoption Revisions & Approvals

MC Rule 350 July 13, 1988 Revised: April 6, 1992; Approved:

September 5, 1995 (60 FR 46024)

Rule 351 February 15, 1995 Approved: February 9, 1998 

(63 FR 6489)

Rule 350-Gasoline Bulk Plants July 13, 1988 Revised: April 6, 1992; Approved:

September 5, 1995 (60 FR 46024)

Rule 353-Service StationsStage IJuly 13, 1988 Revised: April 6, 1992; Approved:

February 1, 1996 (61 FR 3578)

Rule 350-Fixed Roof Petroleum

Tanks

July 13, 1988 Revised: April 6, 1992; Approved:

September 5, 1995 (60 FR 46024) 

Miscellaneous Refinery Sources Negative Declaration Submitted: December 14, 2000;

Approved: August 26, 2002

(67 FR 54741)

Rule 340-Cutback Asphalt July 13, 1988 Revised: June 22, 1992 and

September 21, 1992; Approved:

February 1, 1996

(61 FR 3578)

Rule 331-Solvent Metal Cleaning July 13, 1988 Revised: June 22, 1992, June 19,

1996, and April 21, 2004; Approved:

February 1, 1996 (61 FR 3578),

February 9, 1998 (63 FR 6489), and

December 21, 2004 

(69 FR 76417)

Surface Coating Of:

Rule 336-Cans July 13, 1988 Revised: September 21, 1992, June

19, 1996, and April 7, 1999; Approved:

September 20, 1999 (64 FR 50759)

Rule 336-Metal Coils July 13, 1988 Revised: September 21, 1992, June

19, 1996, and April 7, 1999; Approved:

September 20, 1999 (64 FR 50759)

Rule 336-Fabrics July 13, 1988 Revised: September 21, 1992, June

19, 1996, and April 7, 1999; Approved:

September 20, 1999 (64 FR 50759)

Rule 336-Paper Products July 13, 1988 Revised: September 21, 1992, June

19, 1996, and April 7, 1999; Approved:

September 20, 1999 (64 FR 50759)
2-25

TABLE 2-6

MARICOPA COUNTY VOC RACT RULES AND SIP STATUS (cont.)

CONTROL TECHNIQUES GUIDELINES

Rule Adoption Revisions & Approvals

Automobile & Light Duty Trucks Negative Declaration Submitted: December 14, 2000;

Approved: August 26, 2002

(67 FR 54741)

Rule 336-Metal Furniture July 13, 1988 Revised: September 21, 1992, June

19, 1996, and April 7, 1999; Approved:

September 20, 1999 (64 FR 50759)

Magnetic Wire Negative Declaration Submitted: December 14, 2000;

Approved: August 26, 2002 (67 FR

54741)

Rule 336-Large Appliances July 13, 1988 Revised: September 21, 1992, June

19, 1996, and April 7, 1999; Approved:

September 20, 1999 (64 FR 50759)

Leaks from Petroleum Refineries Negative Declaration Submitted: December 14, 2000;

Approved: August 26, 2002 

(67 FR 54741)

Rule 336-Miscellaneous Metal

Parts Surface Coating

July 13, 1988 Revised: September 21, 1992, June

19, 1996, and April 7, 1999; Approved:

September 20, 1999 (64 FR 50759)

Surface Coating of Flat Wood

Paneling 

Negative Declaration Submitted: December 14, 2000;

Approved: August 26, 2002 (67 FR

54741)

Synthetic Pharmaceutical

Manufacture

Negative Declaration Submitted: December 14, 2000;

Approved: August 26, 2002 (67 FR

54741)

Rubber Tire Manufacture Negative Declaration Submitted: December 14, 2000;

Approved: August 26, 2002 (67 FR

54741)

Rule 350-External Floating Roof

Petroleum Tanks

July 13, 1988 Revised: April 6, 1992; Approved:

September 5, 1995 (60 FR 46024)

Rule 337-Graphic Arts November 20, 1996 Submitted: February 26, 1997;

Approved: February 8, 1998 (63 FR

6489)

Perchloroethylene Dry Cleaning Perchloroethylene was delisted as a

VOC by EPA, effective March 8, 1996

(61 FR 4588)
2-26

TABLE 2-6

MARICOPA COUNTY VOC RACT RULES AND SIP STATUS (cont.)

CONTROL TECHNIQUES GUIDELINES

Rule Adoption Revisions & Approvals

Rule 352-Gasoline Truck Leaks

and Vapor Collection

November 16, 1992 Submitted: February 4, 1993;

Approved: September 5, 1995 (60 FR

46024)

Manufacture of High-Density

Polyethylene Polypropylene, and

Polystyrene Resins

Negative Declaration Submitted: December 14, 2000;

Approved: August 26, 2002 (67 FR

54741)

Fugitive Emissions from

Synthetic Organic Chemical,

Polymer, and Resin

Manufacturing Equipment 

Negative Declaration Submitted: December 14, 2000;

Approved: August 26, 2002 (67 FR

54741)

Rule 333-Large Petroleum Dry

Cleaners

June 19, 1996 Submitted: February 26, 1997;

Approved: February 9, 1998 (63 FR

6489)

Air Oxidation ProcessesSynthetic Organic Chemical

Manufacturing Industries

Negative Declaration Submitted: December 14, 2000;

Approved: August 26, 2002 (67 FR

54741)

Equipment Leaks from Natural

Gas/Gasoline Processing Plants

Negative Declaration Submitted: December 14, 2000;

Approved: August 26, 2002 (67 FR

54741)

Synthetic Organic Chemical

Manufacturing Industries

(SOCMI)-Distillation and Reactor

Processes

Negative Declaration Submitted: December 14, 2000;

Approved: August 26, 2002 (67 FR

54741)

Rule 350- Volatile Organic Liquid

Storage

July 13, 1988 Revised: April 6, 1992; Approved:

September 5, 1995 (60 FR 46024)

SOCMI Batch Processes Negative Declaration Submitted: December 14, 2000;

Approved: August 26, 2002 (67 FR

54741)

Industrial Wastewater Negative Declaration Submitted: December 14, 2000;

Approved: August 26, 2002 (67 FR

54741)

Rule 336-Plastic Parts Coating

(for business machines and

automobiles)

July 13, 1988 Revised: September 21, 1992, June

19, 1996, and April 7, 1999; Approved:

September 20, 1999 (64 FR 50759)
2-27

TABLE 2-6

MARICOPA COUNTY VOC RACT RULES AND SIP STATUS (cont.)

CONTROL TECHNIQUES GUIDELINES

Rule Adoption Revisions & Approvals

Rule 331-Cleaning Solvents July 13, 1988 Revised: June 22, 1992, June 19,

1996, and April 21, 2004; Approved:

February 1, 1996 (61 FR 3578), 

February 9, 1998 (63 FR 6489), and

December 21, 2004 (69 FR 76417)

Rule 337-Offset Lithography November 20, 1996 Submitted: February 26, 1997;

Approved: February 9, 1998 (63 FR

6489)

Shipbuilding and Ship Repair

Coatings

Negative Declaration Submitted: December 14, 2000;

Approved: August 26, 2002 (67 FR

54741)

Rule 342-Wood Furniture November 20, 1996 Submitted: February 26, 1997;

Approved: February 9, 1998 (63 FR

6489)

Rule 348- Aerospace April 7, 1999 Submitted: August 4, 1999; Approved:

September 20, 1999 (64 FR 50759)

Rule 335-Architectural and

Industrial Maintenance (AIM)

Coatings

July 13, 1988 Submitted: January 4, 1990;

Approved: January 6, 1992 (57 FR

354)

Major Sources Subject to RACT

Fiberglass Boat Manufacturing Negative Declaration Submitted: April 21, 2004; Approved:

February 10, 2005 (70 FR 7038) 

Rule 334-Rubber Sports Ball

Manufacturing 

June 19, 1996 Submitted: February 26, 1997;

Approved: February 2, 1998 (63 FR

6489)

Rule 341-Metal Casting August 5, 1994 Submitted: August 16, 1994;

Approved: February 12, 1996 (61 FR

5287)

Rule 343-Commercial Bread

Bakeries 

February 15, 1995 Submitted: August 31, 1995;

Approved: March 17, 1997 (62 FR

12544)
2-28

TABLE 2-6

MARICOPA COUNTY VOC RACT RULES AND SIP STATUS (cont.)

CONTROL TECHNIQUES GUIDELINES

Rule Adoption Revisions & Approvals

Rule 338-Semiconductor

Manufacturing

June 19, 1996 Submitted: February 26, 1997;

Approved: February 9, 1998 (63 FR

6489)

Rule 339-Vegetable Oil

Extraction Processes

November 16, 1992 Submitted: February 4, 1993;

Approved: February 9, 1998 (63 FR

6489)

Rule 346-Coating Wood Millwork November 20, 1996 Submitted: February 26, 1997;

Approved: February 9, 1998 (63 FR

6489)

Rule 347-Ferrous Sand Casting March 4, 1998 Submitted: August 4, 1999; Approved:

June 12, 2000 (65 FR 36788)

Rule 349-Vitamin Manufacturing April 7, 1999 Submitted: August 4, 1999; Approved:

June 8, 2001 (66 FR 30815)

Rule 344-Automotive Windshield

Wiper Fluid

April 7, 1999 Submitted: August 4, 1999; Approved:

November 30, 2001 (66 FR 59699)

Fiberboard for Expansion Joints VOC RACT by permit (W.R.

Meadows); Submitted: April 20,2005;

Approved: June 14, 2005 (70 FR

34357)

Rule 358-Polystyrene Foam

Operations

April 20, 2005 Submitted: April 25, 2005; Approved:

May 26, 2005 (70 FR 30370)
2-29

Ozone Plan (MAG, 2007). The Maricopa County Air Quality Department has recently

completed the 2005 Periodic Emissions Inventory for Ozone Precursors (MCAQD, 2008).

This inventory is provided in Appendix A, Exhibit 1, of this document.

D. The plan provisions shall identify and quantify the emissions of any pollutant allowed

from the construction and operation of major new or modified stationary sources in

the area

The TSD supporting this maintenance plan describes the stationary source emissions for

2005 and 2025, including major new or modified sources. The 2005 stationary source

emissions used as the baseline for the maintenance modeling were provided by the

Maricopa County Air Quality Department and are consistent with the 2005 Periodic

Emissions Inventory in Appendix A, Exhibit 1. The 1992 Memorandum of Agreement for

Air Quality Planning found in Appendix A, Exhibit 2, of the Serious Area Carbon Monoxide

Plan provides the distribution of responsibilities for local air quality planning (MAG, 2001).

The Maricopa County Air Quality Department regulates stationary sources through the

Maricopa County Air Pollution Control Regulations, including Regulation II - Permit and

Fees and Rule 240 - Permit Requirements for New Major Sources and Major Modifications

to Existing Major Sources.

Section 172(c)(4) requires an area, in developing its attainment plan, to identify expected

emission increases that will result from new or modified major sources in a "zone to which

economic development should be targeted" according to Section 173(a)(1)(B). These

provisions effectively allow the State to provide a "growth allowance" for sources in such

an area in lieu of the offset requirements under Section 173(a)(1)(A). This is an optional

alternative to requiring the acquisition of offsets under Section 173(a)(1)(A). Neither the

Maricopa County Air Pollution Control Regulations nor the Arizona Administrative Code

provide a growth allowance in such areas.

E. The plan provisions shall require permits for the construction and operation of new

or modified major stationary sources anywhere in the nonattainment area

Maricopa County received SIP approval of its major and minor source NSR program in

1988 (see 53 FR 30220, 53 FR30224, and 53 FR 30238, August 10, 1988). Effective

November 22, 1993, EPA delegated Prevention of Significant Deterioration (PSD) authority

to Maricopa County via a PSD Delegation Agreement. On August 15, 1994, ADEQ

submitted a SIP revision containing portions of the State permitting program that are

applicable to major sources, major source modifications, and minor sources. Part of the SIP

revision, under a separate cover, included applicable Maricopa County rules, pertinent to

the NSR/PSD program. The amendments to Maricopa County Rules 100, 200, 210, 220,

240, and Appendix B were submitted as a revision to the NSR/PSD program. The

submittal also requested approval of synthetic minor provisions under Section 112 (l) of the

CAA. On September 1, 1994, EPA deemed both the ADEQ and Maricopa County SIP

revision complete and each is currently awaiting full approval. To assure adequate SIP

revisions required by Section 110(a)(2)(E) of the CAA, the Director of ADEQ is authorized
2-30

under ARS §§ 49-402B to assert jurisdiction over major NSR/PSD and minor NSR sources,

excluding those located on Indian Reservations. ADEQ received SIP approval of its

NSR/PSD program effective May 3, 1983 and delegation of PSD authority for PM-10

effective March 12, 1999.

The EPA guidance memorandum, Part D New Source Review (Part D NSR) Requirements

for Areas Requesting Redesignation to Attainment, October 14, 1994, states that

“nonattainment areas may be redesignated to attainment notwithstanding the lack of a fullyapproved Part D NSR program, provided the program is not relied upon for maintenance.”

In addition, the EPA guidance indicates that Part D NSR rules do not need to be placed in

the contingency portion of the maintenance plan. It is important to note that the Eight-Hour

Ozone Maintenance Plan for the Maricopa nonattainment area does not rely on credit for

the NSR program to demonstrate maintenance. 

F. Include enforceable emission limitations and other control measures, means, or

techniques, as well as schedules and timetable for compliance to provide for

attainment of such standard

All of the State control measures for which credit is taken in modeling maintenance of the

eight-hour ozone standard in 2025 have already been implemented. Legally-enforceable

commitments, including the schedules for compliance for these measures were included

in prior EPA-approved plans and programs, including the Serious Area CO Plan (MAG,

2001); the One-Hour Ozone Maintenance Plan (MAG, 2004); the modified Arizona Cleaner

Burning Gasoline Program, effective April 5, 2004; and the final Serious Area Ozone SIP

(ADEQ, 2000), effective June 14, 2005. Timetables have been established for compliance

with the federal nonroad equipment emission standards, for which credit is taken in the

maintenance plan (EPA, 1998 and 2004). 

G. Plans shall meet the applicable requirements of Section 110(a)(2)

Nonattainment plans must show that the requirements under Section 110 are met. These

requirements specify that the plans must contain enforceable emission limits, monitoring

requirements, procedures to prevent interstate pollution problems, adequate resources to

carry out the control programs, and other provisions related to the development and

administration of effective air pollution control programs. These requirements are listed at

the beginning of this section and other discussions in this Chapter demonstrate that the

requirements of Section 110 have been met.

H. States may use equivalent techniques for modeling, emission inventories, planning

procedures unless they are less effective than the methods specified by the

Administrator

The provisions of Section 172(c)(8) allow the State to use equivalent techniques for

modeling, inventories, or other planning activities, unless EPA determines that the

techniques are less effective. This maintenance plan uses models, emission inventories,
2-31

and planning procedures that were documented in the Modeling Protocol in Support of the

Eight-Hour Ozone Redesignation Request and Maintenance Plan (MAG, 2008). The

modeling protocol was reviewed and incorporates recommendations by EPA and the Air

Quality Planning Team. The modeling protocol, included in Appendix I-i of the TSD,

adheres closely to EPA guidance (EPA, 2005).

I. Provide for specific contingency measures to be undertaken if the area fails to make

reasonable further progress, or to attain the NAAQS by the applicable attainment

date

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. Committed measures that have already been

implemented may be contingency measures if they will not hasten attainment or are not

needed to demonstrate attainment or maintenance of the applicable standard. EPA also

allows federal measures to be contingency measures if they are not needed to demonstrate

attainment or maintenance. 

The six contingency measures in the Eight-Hour Ozone Maintenance plan are: Gross

Polluter Option for I/M Program Waivers, Increased Waiver Repair Limit Options, Federal

Heavy Duty Diesel Vehicle Emission Standards, the Liquid Leaker Test as part of the

Vehicle Emission Inspection (VEI) Program, Coordinate Traffic Signal Systems, and

Develop Intelligent Transportation Systems. Emission reduction credit for these

contingency measures was not been taken in modeling maintenance of the eight-hour

ozone standard in 2025. A description of the contingency measures is provided in Chapter

Section IV-7-2 of the TSD.

The next chapter describes the maintenance plan that must be approved by EPA before

the Maricopa area can be redesignated to attainment for the 1997 eight-hour ozone

standard. 
3-1

CHAPTER THREE

MAINTENANCE PLAN

Section 107(d)(3)(E) of the Clean Air Act (CAA) stipulates that the Environmental Protection

Agency (EPA) must fully approve a maintenance plan that meets the requirements of

Section 175A of the CAA before a nonattainment area can be redesignated to attainment.

The maintenance plan is a State Implementation Plan (SIP) revision that demonstrates

maintenance of the relevant National Ambient Air Quality Standard (NAAQS) for at least

ten years beyond the date of the area’s redesignation to attainment by EPA.

As allowed in section 107(d)(3)(D) of the CAA, EPA has indicated that 18 months should

be assumed as the length of time it will take to approve a redesignation request. Due to

uncertainties regarding the timing of EPA’s approval, the year 2025 has been modeled to

ensure that the eight-hour ozone NAAQS will be maintained for at least ten years beyond

the date of EPA’s official notice of redesignation to attainment. 

EPA has established the following core elements that are required for approval of a

maintenance plan:

• Description of control measures for the maintenance period

• Emission inventories for the base and future years

• Maintenance demonstration

• Mobile source emission budgets

• An approved monitoring network and verification of continued attainment

• Contingency provisions

• Subsequent maintenance plan revisions

The remaining sections of this chapter address these core elements of an eight-hour ozone

maintenance plan.

DESCRIPTION OF CONTROL MEASURES FOR THE MAINTENANCE PERIOD

In general, the maintenance plan demonstrates attainment of the eight-hour ozone

standard in 2025 with committed control measures that were used to demonstrate

attainment in the Eight-Hour Ozone Plan (MAG, 2007). Credit for four attainment

measures in the Eight-Hour Ozone Plan have been assumed in demonstrating

maintenance in 2025. The modeling for the maintenance plan also takes credit for the

Federal Nonroad Equipment Emissions Standards and the Expansion of Area A

Boundaries (HB 2538) that were contingency measures in the Eight-Hour Ozone Plan. In

addition, the modeling takes credit for a new ozone measure passed in June 2007 as part

of Arizona Senate Bill 1552 that prohibits open burning during the summer ozone season.

The liquid leaker test, as part of the Arizona Vehicle Emissions Inspection (VEI) Program,
3-2

was also included in S.B. 1552. Since this measure only applies to pre-1996 model year

vehicles, it is assumed that fleet turnover will eliminate these older vehicles by 2025 and

no emission reduction credit was taken for this measure in modeling maintenance.

However, the liquid leaker test will reduce emissions during the maintenance period (i.e.,

2005 through 2025). As a result, this measure is classified as a contingency measure in

the maintenance plan. 

Two attainment measures in the Eight-Hour Ozone Plan, Coordinate Traffic Signal Systems

and Develop Intelligent Transportation Systems, have been reclassified as contingency

measures in the maintenance plan. One other attainment measure in the 2007 Ozone

Plan, Maricopa County Rule 358: Polystyrene Foam Operations, is included in the 2005

baseline emissions for the maintenance plan. Three of the contingency measures in the

Eight-Hour Ozone Plan are also contingency measures in the maintenance plan. 

The committed attainment and contingency measures in the Eight-Hour Ozone Plan were

derived from EPA-approved programs and plans for the Maricopa Area, including the

Modified Arizona Cleaner Burning Gasoline Program, effective April 5, 2004; the Serious

Area Carbon Monoxide Plan (MAG, 2001) and the Carbon Monoxide Maintenance Plan

(MAG, 2003), approved by EPA on April 8, 2005; and the Serious Area Ozone SIP (ADEQ,

2000) and the One-Hour Ozone Maintenance Plan (MAG, 2004), approved by EPA on June

14, 2005. 

Although the one-hour ozone standard was revoked by EPA on June 15, 2005, all

committed control measures in the approved one-hour ozone plans remain in effect as

legally-binding commitments on the part of the State of Arizona, Maricopa County, and local

governments. These permanent and enforceable measures will continue to reduce the

volatile organic compounds (VOC) and nitrogen oxides (NOx) that contribute to the

formation of ozone. 

In addition to measures in these EPA-approved plans, maintenance of the eight-hour ozone

standard through 2025 will be facilitated by more stringent federal emission standards for

light duty motor vehicles and nonroad diesel engines. Together, these federal measures

and the legally-binding commitments contained in prior EPA-approved plans and programs

have been effective in reducing ozone in the nonattainment area, as evidenced by the fact

that there have been no violations of the standard since 2004. 

The committed control measures in the maintenance plan are organized into three groups.

The first group includes those measures for which numeric emission reduction credit was

taken in the modeling for the maintenance demonstration. The first column of Table 3-1

identifies the seven maintenance measures that were used for numeric credit in the

maintenance demonstration. The combined reductions from the maintenance measures,

collectively called the maintenance measure package (MMP), are reflected in the 2025

VOC and NOx emissions summarized later in this chapter. 
3-3

TABLE 3-1

COMMITTED MAINTENANCE MEASURES AND CONTINGENCY MEASURES

IN THE EIGHT-HOUR OZONE MAINTENANCE PLAN

Maintenance Measures

Used for Numeric Credit Contingency Measures

1. Summer Fuel Reformulation: California

Phase 2 and Federal Phase II

Reformulated Gasoline with 7 psi from

May 1 through September 30

1. Gross Polluter Waiver Provision

2. Phased-In Emission Test Cutpoints

(I/M 147 Program)

2. Increased Waiver Repair Limit

3. One Time Waiver from Vehicle

Emissions Test

3. Federal Heavy Duty Diesel Vehicle

Emissions Standards

4. Tougher Enforcement of Vehicle

Registration and Emission Test

Compliance

4. Coordinate Traffic Signal Systems

5. Federal Nonroad Equipment Emissions

Standards

5. Develop Intelligent Transportation

Systems

6. Expansion of Area A Boundaries

(HB 2538)

6. Liquid Leaker Test as Part of VEI

Program

7. Ban Open Burning During Ozone

Season
3-4

The second group of control measures includes the committed contingency measures that

are part of the maintenance plan. No emission reduction credit was taken for these

measures in the modeling for the maintenance demonstration and the impact of these

measures is not reflected in the 2025 emissions. The six contingency measures are listed

in the second column of Table 3-1.

The third group of control measures includes the committed measures from EPA-approved

plans that were not used for numeric credit in those plans. These plans include the Serious

Area Carbon Monoxide Plan (MAG, 2001), Carbon Monoxide Maintenance Plan (MAG,

2003), Serious Area Ozone SIP (ADEQ, 2000), and One-Hour Ozone Maintenance Plan

(MAG, 2004). The emission reductions attributable to these measures were not easily

quantified or may not have been possible to quantify. However, these measures will

continue to reinforce the air quality benefits of the other committed measures in the

maintenance plan.

Measures Used for Numeric Credit

The maintenance plan assumes numeric credit for four measures that were also quantified

as attainment measures in the 2007 Eight-Hour Ozone Plan. In addition, numeric credit

has been taken in the maintenance plan for three additional measures: federal nonroad

equipment standards, the expansion of Area A boundaries (HB 2538), and the ban on open

burning during the ozone season. The federal nonroad emission standards and expansion

of Area A were contingency measures in the 2007 Eight-Hour Ozone Plan. The ban on

open burning in S.B. 1552 was not passed in time to be included in the 2007 Eight-Hour

Ozone Plan.

Descriptions of the seven maintenance measures for which numeric credit was taken are

provided in Chapter Two. Figures 3-1 and 3-2 illustrate the percent reductions in

anthropogenic VOC and NOx emissions, respectively, due to implementation of the

individual maintenance measures. Table 3-2 quantifies the emission reductions from these

individual measures in metric tons per day.

The base total 2025 anthropogenic emissions shown in Table 3-2 were estimated by

removing the emission reductions due to the seven maintenance measures from the

emissions used to model a Thursday in June 2025. Thursday is the day of the week during

the June episode in 2002 when the highest eight-hour ozone concentrations were

measured at monitors in the Maricopa nonattainment area.

A comparison of 2025 anthropogenic emissions by source category with and without the

seven maintenance measures is shown in Tables 3-3 and 3-4 for VOC and NOx,

respectively. Comparable pie charts are provided at the bottom of each table. Biogenic

emissions are not included in these tables and pie charts, because the maintenance

measures do not reduce biogenic emissions. 
3-5

FIGURE 3-1

2025 ANTHROPOGENIC VOC EMISSION REDUCTIONS

FOR INDIVIDUAL MAINTENANCE MEASURES
3-6

FIGURE 3-2

2025 ANTHROPOGENIC NOx EMISSION REDUCTIONS

FOR INDIVIDUAL MAINTENANCE MEASURES
3-7

TABLE 3-2

2025 EMISSION REDUCTIONS FOR INDIVIDUAL MAINTENANCE MEASURES

IN METRIC TONS PER DAY

VOC NOx

Base Total Anthropogenic

Emissions on a Thursday in

June 2025 (metric tons/day)

244.1 285.8

Maintenance Measure

Emission

Reductions

(metric

tons/day)

Percent

Reduction in

Anthropogenic

Emissions

Emission

Reductions

(metric

tons/day)

Percent

Reduction in

Anthropogenic

Emissions

1. Summer Fuel

Reformulation: California

Phase 2 and Federal Phase

II Reformulated Gasoline

with 7 psi from May 1

through September 30

1.3 0.5% 0.4

(increase)

 0.1%

(increase)

2. Phased-In Emission Test

Cutpoints < 0.1 < 0.1% < 0.1 < 0.1%

3. One Time Waiver from

Vehicle Emissions Test 0.2 < 0.1% 0.3 0.1%

4. Tougher Enforcement of

Vehicle Registration and

Emission Test Compliance

0.2 < 0.1% 0.4 0.1%

5. Federal Nonroad

Equipment Emissions

Standards

19.3 7.9% 47.2 16.5%

6. Expansion of Area A

Boundary (H.B. 2538) 0.2 < 0.1% 0.4 0.1%

7. Ban Open Burning during

Ozone Season < 0.1 < 0.1% < 0.1 < 0.1%
3-8

TABLE 3-3

2025 ANTHROPOGENIC VOC EMISSIONS

WITH AND WITHOUT THE MAINTENANCE MEASURE PACKAGE (MMP)

Source

Category

Base Anthropogenic

VOC Emissions on a

Thursday in June

2025

(metric tons/day)

Anthropogenic VOC

Emissions with MMP

on a Thursday in June

2025

(metric tons/day)

2025 MMP vs Base

Anthropogenic

VOC Emissions

(%)

Point 18.7 18.7 0.0

Area 124.8 124.8 0.0

Nonroad 50.8 31.8 -37.4

Onroad 49.8 47.9 -3.8

Total 244.1 223.2 -8.6

Note: The percent total may not be equal to 100% due to rounding.
3-9

TABLE 3-4

2025 ANTHROPOGENIC NOx EMISSIONS

WITH AND WITHOUT THE MAINTENANCE MEASURE PACKAGE (MMP)

Source Category

Base Anthropogenic

NOx Emissions on a

Thursday in June

2025

(metric tons/day)

Anthropogenic NOx

with the MMP on a

Thursday in June

2025

(metric tons/day)

2025 MMP vs. Base

Anthropogenic NOx

Emissions

(%)

Point 59.1 59.1 0.0

Area 31.1 31.1 0.0

Nonroad 85.1 37.9 -55.5

Onroad 110.5 109.8 -0.6

Total 285.8 237.8 -16.8

Note: The percent total may not be equal to 100% due to rounding.
3-10

The total reduction in anthropogenic emissions due to the package of seven maintenance

measures in June 2025 is 8.6 percent for VOC and 16.8 percent for NOx. The

methodologies for quantifying the emission reductions for the individual measures are

described in Section IV-7-1 of Appendix A, Exhibit 2, the Technical Support Document for

Ozone Modeling in Support of the Eight-Hour Ozone Redesignation Request and

Maintenance Plan for the Maricopa Nonattainment Area (TSD).

Contingency Measures

The six contingency measures for the maintenance plan are described in Section VI-7-2

of the TSD. All of the contingency measures listed in Table 3-1 have already been

implemented in the nonattainment area. Early implementation of contingency measures

is allowed by EPA (EPA, 1993) and helps to ensure that the standard will be maintained

through 2025. 

EPA also allows the use of federal measures as contingency measures, if credit for these

measures is not taken in the maintenance demonstration. No credit was quantified in this

maintenance plan for the contingency measures. A later section in this Chapter discusses

the procedures that will be followed to consider and implement additional contingency

measures, if they are needed.

Measures Which Improve Air Quality, But Were Not Used for Numeric Credit

The third group of measures in the maintenance plan represents commitments in the EPAapproved Serious Area Carbon Monoxide Plan, Carbon Monoxide Maintenance Plan,

Serious Area Ozone SIP, and One-Hour Ozone Maintenance Plan. Ozone precursor

emission reduction credit for these measures were not easily quantified or may not have

been possible to quantify. Detailed descriptions of these committed control measures are

contained in Chapter Eight of the Serious Area Carbon Monoxide Plan, Chapter Three of

the Carbon Monoxide Maintenance Plan, Chapter Two of the Serious Area Ozone SIP, and

Chapter Two of the One-Hour Ozone Maintenance Plan. 

EMISSION INVENTORIES FOR THE BASE AND FUTURE YEARS

This section discusses the 2005 and 2025 emissions used in modeling maintenance of the

eight-hour ozone standard. The 2005 and 2025 emissions were developed for the three

ozone episodes that were modeled in the attainment demonstration for the Eight-Hour

Ozone Plan. The June 2002, July 2002, and August 2001 episodes are described in

Section II-3-4 of the TSD. A more detailed discussion of these episodes is provided in

Appendix A, Exhibit 2, of the Eight-Hour Ozone Plan for the Maricopa Nonattainment Area

(MAG, 2007).

Onroad mobile source emissions for 2005 were developed using estimates of 2005

population and employment based on the Special U.S. Census conducted for Maricopa

County in 2005. Population and employment are key inputs to the MAG transportation
3-11

model that produces the vehicle miles of travel (VMT) and speeds used in calculating

onroad mobile source emissions with the EPA MOBILE6.2 model. 

The 2005 emissions assume credit for committed control measures that were in place

during the summer of 2005. Table 3-5 summarizes the key assumptions used in

developing the 2005 emissions. Section IV-1 of the TSD discusses the methods and

assumptions used to develop the 2005 baseline emissions. 

In general, the 2005 emissions used in modeling maintenance are consistent with the 2005

periodic emission inventory for ozone precursors developed by the Maricopa County Air

Quality Department (MCAQD, 2008). A comparison of the 2005 MAG baseline emissions

used in modeling and the 2005 periodic emissions inventory is provided in Appendix IV-iv

of the TSD.

The VOC and NOx emissions used to model maintenance in 2025 include reduction credit

for the seven committed maintenance measures. Table 3-5 summarizes the key

assumptions used in developing the 2025 emissions used to demonstrate maintenance.

Section IV-2 of the TSD details the methods and assumptions used to develop the 2025

ozone precursor emissions. 

Emissions for point and area sources were projected from 2005 to 2025 by application of

appropriate growth factors. The growth factors were based on the latest population and

employment projections approved by the MAG Regional Council in May 2007. A detailed

description of the assumptions used in developing the 2025 point and area source

emissions is provided in Section IV-2-2-4 of the TSD. 

For power plants, the Potential to Emit (PTE) rates provided by MCAQD were assumed for

2025. To demonstrate permanent and enforceable improvement in air quality, EPA

guidance in "Procedures for Processing Requests for Redesignation to Attainment" (EPA,

1992) states that "the analysis should assume that sources are operating at permitted

levels (or historic peak levels) unless evidence is presented that such an assumption is

unrealistic." The PTE rates assumed for power plants in 2025 represent the maximum

levels currently permitted by MCAQD for power plants that are expected to be operating

in 2025. The anticipated growth in population and industry between 2005 and 2025 will

increase the demand for electricity in the eight-hour ozone nonattainment area. In addition,

the summer ozone season is the time of year when peak demand typically occurs. In

general, the uncertainties inherent in long-range power generation forecasts support the

use of PTE rates for the maintenance demonstration.

With the exception of commercial lawn and garden equipment, the growth factors for

projecting 2005 nonroad emissions to 2025 were derived from the EPA NONROAD2005

model defaults for Maricopa County. The assumptions used in developing the 2025

nonroad emissions are discussed in Section IV-2-2-3 of the TSD. 
1

Excluding vintage vehicles.

2

Excluding vintage vehicles and motorcycles.

3

Waiver rate was reduced from 4% for pre-1981 vehicles and 3% for 1981+ vehicles due

to the measure: One-Time Waiver from Vehicle Emissions Test.

4

Participation in the I/M program was increased by 2% due to the measure: Tougher 

Enforcement of Vehicle Registration and Emissions Test Compliance.

5

420-F-08-004 and 40 CFR Chapter 1, Subpart H. It is important to note, however, that 

the lower federally-mandated sulfur contents do not reduce VOC or NOx emissions.

6

Efficiency provided by Duane Yantorno, Arizona Department of Weights and Measures.

3-12

TABLE 3-5

KEY ASSUMPTIONS USED TO DEVELOP 2005 AND 2025 EMISSIONS

FOR THE MAINTENANCE DEMONSTRATION

2005 2025

1. Oxygenate content, reid vapor pressure

(RVP), and sulfur content for onroad

mobile emissions based on actual fuel

properties provided by the AZ Department

of Weights and Measures (ADWM)

1. Summer Fuel Reformulation:

California Phase 2 and Federal Phase II

Reformulated Gasoline with 7 psi from

May 1 - September 30

2. Enhanced Inspection/Maintenance (I/M)

for all vehicles1

 in Area A with Phased-In

Emission Test Cutpoints (I/M 147) 

2. Enhanced Inspection/Maintenance (I/M)

for all vehicles2

 in Area A with Phased-In

Emission Test Cutpoints (I/M 147)

3. Waiver rate for pre-1981 vehicles =

0.709%; 1981+ vehicles = 0.781%3

3. Waiver rate for pre-1981 vehicles =

0.709%; 1981+ vehicles = 0.781%

4. Vehicles participating in the I/M program:

91.6%; not participating: 8.4%4

4. Vehicles participating in the I/M program:

91.6%; not participating: 8.4%

5. Federal Light Duty Vehicle Emissions

Standards (Tier 2)

5. Federal Light Duty Vehicle Emissions

Standards (Tier 2)

6. Federal Nonroad Equipment Emission

Standards (Tier 2)

6. Federal Nonroad Equipment Emission

Standards (Tiers 2, 3, and 4)

7. RVP and sulfur content for nonroad

mobile emissions based on actual fuel

properties provided by the ADWM

7. Sulfur content of diesel fuel for nonroad

equipment = 15 ppm; sulfur content of

gasoline for nonroad equipment = 30 ppm5

8. Phase II vapor recovery - 46% efficiency6 8. Phase II vapor recovery - 46% efficiency

9. Power plant emissions based on actual

operating levels in 2005

9. Power plant emissions based on

maximum Potential to Emit (PTE) levels
3-13

Onroad mobile source emissions for 2025 were based on the population and employment

projections adopted by the MAG Regional Council in May 2007. To provide safety margins

for transportation conformity budgets, the onroad mobile VOC and NOx emissions in the

ozone modeling domain were increased by ten percent in 2025. Spatially, this increase

was applied proportionately to the onroad mobile source emissions in each four kilometer

grid cell. The methods and assumptions used in developing the onroad mobile source

emissions are described in Section IV-2-2-1 of the TSD. 

Biogenic emissions used in the maintenance plan were derived from the MAG Biogenics

Study (ENVIRON, 2006). The same gridded biogenic emissions used in modeling

attainment in the Eight-Hour Ozone Plan (MAG, 2007a) were used in modeling

maintenance of the eight-hour ozone standard. The biogenic emissions are described in

Section IV-2-2-2 of the TSD.

The 2005 and 2025 VOC and NOx emissions for the peak episode day in June are

summarized by source category in Tables 3-6 and 3-7, respectively. Comparable pie charts

of the 2005 and 2025 emissions are provided at the bottom of each table. The emissions

for the June episode day are shown because the highest ozone concentrations occurred

under the meteorological and pollutant transport conditions associated with that episode

day on June 6, 2002. Summaries of the 2005 and 2025 emission inventories for the July

and August episode days with the highest ozone concentrations are shown in Section IV-2-

2-6 of the TSD.

Between 2005 and 2025, onroad mobile emissions decline by more than one-third for VOC

and almost 30 percent for NOx. Over this same period, nonroad emissions are also

reduced by 21 percent for VOC and more than 50 percent for NOx. These significant

decreases in mobile source emissions occur despite a 76 percent increase in vehicle travel

over the twenty year period, due to the phasing in of new light duty vehicles and nonroad

equipment that must meet more stringent, federally-mandated emission standards (i.e., Tier

2 and Tiers 2-4, respectively). 

Biogenic and onroad mobile sources contribute the largest share of emissions in both 2005

and 2025 for VOC and NOx, respectively. In 2005 and 2025, area sources contribute the

highest percent of anthropogenic VOC emissions (12 percent and 19 percent, respectively).

Between 2005 and 2025, the combined share of onroad and nonroad source emissions

decline from 17 to 12 percent of total VOC emissions, while the share of point and area

source emissions increase from 14 to 21 percent. 

Similarly, the onroad and nonroad share of NOx emissions decreases from 86 percent in

2005 to 60 percent in 2025. However, as noted in Table 3-5, power plants were assumed

to emit maximum levels of NOx in 2025, whereas the 2005 power plant emissions

represent actual operating levels. This conservative modeling assumption has the effect

of increasing point source emissions from 4 percent of the total NOx emissions in 2005 to

24 percent in 2025.
3-14

TABLE 3-6

VOC EMISSIONS FOR A JUNE EPISODE DAY IN 2005 AND 2025

Source

Category

Thursday in June,

2005

(metric tons/day)

Thursday in June,

2025

(metric tons/day)

2025-2005 Difference

(%)

Point 11.1 18.7 68.5

Area 79.2 124.8 57.5

Nonroad 40.3 31.8 -21.0

Onroad 72.1 47.9 -33.6

Biogenics 451.3 451.3 0.0

Total 653.9 674.4 3.1

Note: The percent total may not be equal to 100% due to rounding.

VOC for a Thursday in June, 2025

Total : 674.42 metric tons/day

Point

2.8% Area

18.5%

Onroad

7.1%

Nonroad

Biogenics 4.7%

66.9%

VOC for a Thursday in June, 2005

Total: 653.93 metric tons/day

Biogenics

69.0%

Nonroad

6.2%

Onroad

11.0%

Area

12.1%

Point

1.7%
3-15

TABLE 3-7

NOx EMISSIONS FOR A JUNE EPISODE DAY IN 2005 AND 2025

Source

Category

Thursday in June,

2005

(metric tons/day)

 Thursday in June,

2025

(metric tons/day)

2025-2005 Difference

(%)

Point 10.9 59.1 440.3

Area 19.6 31.1 58.8

Nonroad 77.7 37.9 -51.2

Onroad 154.3 109.8 -28.9

Biogenics 8.6 8.6 0.0

Total 271.1 246.4 -9.1

Note: The percent total may not be equal to 100% due to rounding.

NOx for a Thursday in June, 2005

Total: 271.06 metric tons/day

Point

4.0% Area

7.2%

Onroad

56.9%

Nonroad

28.6%

Biogenics

3.2%

NOx for a Thursday in June, 2025

Total: 246.39 metric tons/day

Onroad

44.6%

Area

12.6%

Point

24.0%

Biogenics

3.5% Nonroad

15.4%
3-16

MAINTENANCE DEMONSTRATION

The modeling for the 2025 maintenance demonstration was performed with the EPAapproved Comprehensive Air Quality Model with Extensions (CAMx). Details on the

selection, validation and application of CAMx are provided in Section III of the TSD. To

demonstrate maintenance of the 1997 eight-hour ozone standard, the CAMx modeling for

2025 must show that predicted eight-hour ozone design values are less than 0.085 ppm

throughout the ozone modeling domain for every episode. The 2025 maximum simulated

eight-hour ozone concentrations for each episode are provided in Table 3-8. All three of

these simulated maximum values occurred near the North Phoenix ozone monitor. 

MAG performed a number of supplemental tests to corroborate the CAMx modeling results

in 2025. One of these tests was an unmonitored area analysis, using the EPA Modeled

Attainment Test Software (MATS), to ensure that areas that are not near existing air quality

monitors also meet the standard in 2025. The maximum ozone design values produced

by the MATS analysis were 0.081 ppm for the June episode, 0.079 ppm for the July

episode, and 0.083 ppm for the August episode in 2025. 

In order to determine the sensitivity of the maintenance demonstration to a range of power

plant emission rates, MAG also performed supplemental analyses for 2025 that replaced

the PTE rates with 2005 baseline power plant emission rates. The supplemental analyses

included CAMx/MM5 modeling and unmonitored area analysis. Both analyses concluded

that the eight-hour ozone standard would be maintained in 2025 with 2005 power plant

emission rates. These supplemental analyses, described in Appendix IV-viii of the TSD,

provide convincing evidence that the standard will be maintained in the future, with power

plant emission rates ranging from minimum (2005) to maximum (PTE) levels. 

Figure 3-3 provides an isopleth plot of the results of the unmonitored area analysis overlaid

with the values predicted by modeling each monitoring site on the June 2025 episode day.

The eight-hour ozone concentrations are shown in parts per billion (ppb).

Since the maximum monitored and unmonitored area ozone concentrations for all episodes

are less than 0.085 ppm, maintenance of the eight-hour ozone standard has been

demonstrated for the Maricopa nonattainment area in 2025. Technical details supporting

the modeling and supplemental analyses for the maintenance demonstration are provided

in Sections V and VI of the TSD.
3-17

TABLE 3-8 

MAXIMUM MODELED EIGHT-HOUR OZONE CONCENTRATIONS

FOR THE JUNE, JULY AND AUGUST EPISODES IN 2025

Modeled Episode

Maximum Design Value in the 

Eight-Hour Ozone Modeling Domain

June 2025 0.081 ppm

July 2025 0.079 ppm

August 2025 0.079 ppm
3-18

FIGURE 3-3

PREDICTED EIGHT-HOUR OZONE CONCENTRATIONS IN JUNE 2025

(in ppb)

72

81

73.8

75.3

75.2

74.6

75.8

72.1

73.3

74.9

76.4

65.4

62.4

68.2

78.1

71.1

79.7

79.3

73.3

70.6

68.2

63

61.5

67.8

77.5

WP

NP

FF

GL

PP

CP

SS

SP

WC

TEMP

CC

DY

BE

LV

HM

BP

FH

RV

SUPR

AJ

CG

QC

MCPA

SAC

QV

300000 320000 340000 360000 380000 400000 420000 440000 460000 4800

366000036800003700000372000037400003760000
3-19

MOBILE SOURCE EMISSION BUDGETS

In accordance with the 1990 Clean Air Act Amendments (CAAA), transportation 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

Maricopa County is the Maricopa Association of Governments.

Section 176(c) of the 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. These 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 demonstrations, for any criteria

pollutant or its precursors, allocated by the applicable implementation plan to highway and

transit vehicles.”

MAG submitted the Eight-Hour Ozone Plan to EPA in June 2007 (MAG, 2007). This plan

demonstrated attainment of the eight-hour ozone standard by the ozone season of 2008

and contained 2008 conformity budgets for VOC and NOx. EPA found these eight-hour

ozone conformity budgets to be adequate, effective November 7, 2007. The 2008 budgets

of 67.9 metric tons per day for VOC and 138.3 metric tons per day for NOx represent

onroad mobile source emissions in the eight-hour ozone nonattainment area. These

budgets from the 2007 Eight-Hour Ozone Plan were used in the 2008 MAG Conformity

Analysis.

In addition to the 2008 conformity budgets established in the 2007 Eight-Hour Ozone Plan,

this maintenance plan establishes 2025 conformity budgets based on the 2025 onroad

mobile source VOC and NOx emissions used to model maintenance in the eight-hour

ozone nonattainment area. These maintenance budgets include emission reduction credit

for the committed maintenance measure package. The 2025 maintenance budgets are

derived from the onroad mobile VOC and NOx emissions on the peak episode day in June

2025. This is comparable to the episode day, June 6, 2002, which had the highest ozone

concentrations. 
3-20

As shown in Tables 3-6 and 3-7, the onroad mobile emissions in the eight-hour ozone

modeling domain on the peak episode day in June 2025 are 47.9 metric tons per day for

VOC and 109.8 metric tons per day for NOx. A GIS analysis was performed to extract the

onroad mobile emissions in the eight-hour ozone nonattainment area from the larger eighthour ozone modeling domain. The resultant onroad mobile source emissions for the eighthour nonattainment area are 43.8 metric tons per day for VOC and 101.8 metric tons per

day for NOx. These represent the 2025 maintenance budgets for transportation conformity

purposes.

MAG will use these new 2025 VOC and NOx emission budgets in conformity analyses that

begin after these budgets have been found to be adequate or are approved by EPA as part

of the Eight-Hour Ozone Redesignation Request and Maintenance Plan. In subsequent

conformity analyses, onroad mobile source emissions for conformity horizon years of 2008

through 2024 can not exceed the 2008 VOC and NOx emission budgets, while onroad

mobile emissions in horizon years after 2024 can not exceed the 2025 maintenance

budgets for VOC and NOx.

The methods and assumptions used to estimate onroad mobile source emissions in 2025

are documented in Section IV-2 of the TSD. The models and assumptions used in

estimating onroad mobile source emissions for future conformity analyses may differ from

those described in the TSD, because the latest emission models and other planning

assumptions (e.g., vehicle registrations, speeds, population, and vehicle miles of travel)

must be used each time a conformity analysis is performed (FHWA, 2001).

Due to the inherent uncertainties associated with use of the latest planning assumptions

in conformity analyses, the 2025 VOC and NOx emissions from onroad mobile sources

were increased by ten percent in the eight-hour ozone (4 kilometer) modeling domain to

create a safety margin for the conformity budgets. EPA has indicated that safety margins

are allowed, if maintenance can be modeled with the increased emissions (EPA, 2007). 

The VOC and NOx emissions from onroad mobile sources were increased by ten percent

for all three modeled episodes. The increase was distributed spatially in the ozone

modeling domain based on the proportion of onroad mobile emissions assigned to each

four kilometer grid cell. Since maintenance was demonstrated with the increased onroad

mobile source emissions, the 2025 conformity budgets in the maintenance plan incorporate

a safety margin.

AN APPROVED MONITORING NETWORK AND VERIFICATION OF CONTINUED

ATTAINMENT

The air quality monitoring data shown in Chapter Two confirms that the Maricopa

nonattainment area attained the 1997 eight-hour ozone standard during the ozone season

of 2008, as modeled in the Eight-Hour Ozone Plan. The three year average (i.e., 2006-

2008) of the annual fourth highest eight-hour ozone concentrations at all monitors was less

than 0.085 ppm, which means that the area has met the attainment date of June 15, 2009,
3-21

as required by the Clean Air Act. The monitoring data also indicate that the eight-hour

ozone concentrations have been trending downward and there have been no violations of

the ozone standard at any monitor since 2004. 

After the Maricopa nonattainment area has been redesignated to attainment by EPA, the

Arizona Department of Environmental Quality (ADEQ) and the Maricopa County Air Quality

Department (MCAQD) will continue to operate an appropriate air quality monitoring network

of National Air Monitoring Stations (NAMS) and State and Local Air Monitoring Stations

(SLAMS) in accordance with 40 CFR Part 58 to verify the continued attainment of the

ozone standard. If measured parameters (e.g., population, vehicle miles of travel,

significant sources) change significantly over time, ADEQ and MCAQD will perform the

appropriate studies to determine whether additional and/or re-sited monitors are necessary.

Annual review of the NAMS/SLAMS air quality surveillance system will continue to be

conducted in accordance with 40 CFR 58.20(d) to determine whether the system continues

to meet the monitoring objectives presented in Appendix C of 40 CFR Part 58.

In order to track the progress of the Maintenance Plan, periodic emission inventories of

ozone precursors will continue to be prepared every three years in accordance with Section

187(a)(5) of the Clean Air Act. Maricopa County will coordinate and compile the inventory

with input and assistance from ADEQ, the Arizona Department of Transportation, and

MAG, as described in the 1992 Air Quality Memorandum of Agreement. Changes in the

inventory will be reviewed and evaluated through the regional air quality planning process

to determine if additional measures should be considered.

The 2005 Periodic Emission Inventory for Ozone Precursors for the Maricopa County,

Arizona, Nonattainment Area is contained in Appendix A, Exhibit 1. Generally, the 2005

baseline emissions used in the maintenance demonstration and the 2005 periodic

emissions inventory are in close agreement, as indicated in the comparison provided in

Appendix IV-iv of the TSD. 

CONTINGENCY PROVISIONS

Section 175A(d) of the Clean Air Act requires that maintenance plans contain contingency

provisions. EPA guidance on the required content of the maintenance plan is provided in

the September 4, 1992 EPA memorandum. This memo indicates that the maintenance

plan is not required to contain fully adopted contingency measures. However, the plan

should contain clearly identified contingency measures to be adopted, a schedule and

procedures for adoption and implementation, and a specific time limit for action by the

State. In addition, specific indicators should be identified which will be used to determine

when the contingency measures need to be implemented. 

Consistent with the August 13, 1993 EPA guidance memorandum titled, “Early

Implementation of Contingency Measures for Ozone and Carbon Monoxide (CO)
3-22

Nonattainment Areas,” the contingency measures described in this Eight-Hour Ozone

Maintenance Plan are comprised of committed control measures that are expected to be

implemented early. An example of early implementation of contingency measures in a

maintenance plan that has been approved by EPA is the redesignation of the Salt Lake City

Carbon Monoxide Nonattainment Area to attainment (see page 3216 of the January 21,

1999 Federal Register). In that action, EPA noted that both contingency measures in the

Salt Lake City contingency plan had already been partially implemented.

There are six contingency measures in the Eight-Hour Ozone Maintenance Plan: Gross

Polluter Option for I/M Program Waivers; Increased Waiver Repair Limit Options; Federal

Heavy Duty Diesel Vehicle Emissions Standards; Liquid Leaker Test as Part of the Vehicle

Emissions Inspection (VEI) Program; Coordinate Traffic Signal Systems; and Develop

Intelligent Transportation Systems. A description of the individual contingency measures

is provided in Section IV-7-2 of the TSD. Emission reduction credit for these six

contingency measures was not taken in modeling maintenance of the eight-hour ozone

standard. Early and continued implementation of these contingency measures provides

additional confidence that the eight-hour ozone standard will be maintained through 2025.

In order to meet the contingency provision requirements of a maintenance plan, ambient

air quality monitoring data will be examined to determine if additional contingency

measures are needed. Contingency provisions will be triggered when the three-year

average of the annual fourth highest daily eight-hour ozone concentration exceeds 84 ppb

at any ozone monitor. If this occurs, additional control measures will be considered, which

may include the strengthening of existing contingency measures. 

When the contingency trigger is activated, the following schedule of actions would be

followed: (A) Verification of the monitoring data to be completed three months after

activation of the trigger; (B) Applicable control measures to be considered for adoption six

months after the date established in A above; and (C) Resultant committed measures to

be implemented within six to twelve months, depending upon the time needed to put the

measures in place.

SUBSEQUENT MAINTENANCE PLAN REVISIONS

Section 175A(b) of the Clean Air Act requires that a maintenance plan revision be

submitted to EPA eight years after redesignation of the area to attainment. The purpose

of the revision is to provide for maintenance of the ozone NAAQS for an additional ten

years beyond the first maintenance period. As the designated Regional Air Quality

Planning Agency for the Maricopa County area, MAG intends to prepare the revised

maintenance plan required by the Clean Air Act eight years after redesignation to

attainment.
R-1

REFERENCES

ADEQ, 2000. “Serious Area Ozone State Implementation Plan for Maricopa County.”

Prepared by the Arizona Department of Environmental Quality. December 14, 2000.

EPA, 1993. “Early Implementation of Contingency Measures for Ozone and Carbon

Monoxide (CO) Nonattainment Areas.” Prepared by G.T. Helms, EPA Chief,

Ozone/Carbon Monoxide Programs Branch. August 13, 1993.

EPA, 1998. “Control of Emissions of Air Pollution from Nonroad Diesel Engines, Final

Rule.” Federal Register, Vol. 63, No. 205. October 23, 1998.

EPA, 1992. “Procedures for Processing Requests to Redesignate Areas to Attainment.”

Memorandum issued by EPA. September 4, 1992.

EPA, 2004. “Control of Emissions of Air Pollution from Nonroad Diesel Engines and Fuel,

Final Rule.” Federal Register, Vol. 69, No. 124. June 29, 2004.

EPA, 2005. “Guidance on the Use of Models and Other Analyses in Attainment

Demonstrations for the 8-hour Ozone NAAQS.” February 17, 2005.

EPA, 2007. “Conference calls with EPA Region IX staff on April 19 and 27, 2007.

FHWA, 2001. “Use of Latest Planning Assumptions in Conformity Determinations.”

Memorandum issued jointly by FHWA, FTA, and EPA. January 18, 2001.

MAG, 2001. “Revised MAG 1999 Serious Area Carbon Monoxide Plan for the Maricopa

County Nonattainment Area.” Prepared by the Maricopa Association of Governments.

March 2001. 

MAG, 2003. “Carbon Monoxide Redesignation Request and Maintenance Plan for the

Maricopa County Nonattainment Area.” Prepared by the Maricopa Association of

Governments. May 2003.

MAG, 2004. “One-Hour Ozone Redesignation Request and Maintenance Plan for the

Maricopa County Nonattainment Area.” Prepared by the Maricopa Association of

Governments. March 2004.

MAG, 2007. “Eight-Hour Ozone Plan for the Maricopa Nonattainment Area.” Prepared by

the Maricopa Association of Governments. June 2007.

MAG, 2008. “Modeling Protocol in Support of the Eight-Hour Ozone Redesignation

Request and Maintenance Plan for the Maricopa Nonattainment Area.” Prepared by the

Maricopa Association of Governments. May 2008.
R-2

MCAQD, 2008. “2005 Periodic Emission Inventory for Ozone Precursors in the Maricopa

County, Arizona, Nonattainment Area.” September 2008.

NOAA, 2008. Data obtained from the National Oceanic and Atmospheric Administration

National Data Centers by MAG staff. September 12, 2008.