FINAL

2009 1997 8-HOUR OZONE 

MODIFIED 

AIR QUALITY MANAGEMENT PLAN

AIR POLLUTION CONTROL 

DISTRICT

JULY 13, 2010
FINAL 2009 1997 8-HOUR OZONE MODIFIED AQMP

ADOPTED JULY 13, 2010

i

TABLE OF CONTENTS

Chapter 1 – Introduction/Background ............................................................... 1

1.1 Introduction................................................................................................ 2

1.2 Purpose ...................................................................................................... 3

1.3 Background................................................................................................ 3

1.4 Ozone Production and Health Effects...................................................... 4

1.5 Responsibility of Agencies ....................................................................... 6

Chapter 2 – Planning Area.................................................................................... 9

2.1 Physical Description of the Planning Area.............................................. 10

2.2 Climate........................................................................................................ 10

2.3 Atmospheric Stability and Dispersion ..................................................... 11

2.4 Land Use..................................................................................................... 12

2.5 Population .................................................................................................. 12

Chapter 3 – Existing Air Quality........................................................................... 13

3.1 Air Quality Standards ................................................................................ 14

3.2 Air Quality Monitoring ............................................................................... 15

3.3 Local Ozone Measurements...................................................................... 18

Chapter 4 – Emission Inventory........................................................................... 21

4.1 Introduction................................................................................................ 22

4.2 Emissions Source Classification System................................................ 23

4.3 2002 Baseline Inventory Categories......................................................... 23

Chapter 5 – Control Measures ............................................................................. 28

5.1 Introduction................................................................................................ 29

5.2 Control Measure Analysis......................................................................... 29

5.3 Stationary Source Control Measures ....................................................... 30

5.4 Transportation Control Measures ............................................................ 36

5.5 Incentive Programs.................................................................................... 40

5.6 State Strategy............................................................................................. 41

Chapter 6 – Emission Forecast............................................................................ 43

6.1 Introduction................................................................................................ 44

6.2 Forecast Methods and Assumptions ....................................................... 44

6.3 External Adjustments to Emissions Inventory........................................ 46

6.4 Emissions Inventory Forecast.................................................................. 47

6.5 Emissions Inventory Trends..................................................................... 49

6.6 Transportation Conformity........................................................................ 50

Chapter 7 – Conclusions and SIP Checklist ....................................................... 52

7.1 Checklist of SIP Requirements................................................................. 53
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LIST OF APPENDICES

APPENDIX A (Approval and Promulgation of Air Quality 

Implementation Plans; California Determination of 

Attainment of the 1997 8- Hour Ozone Standard) ..................... 56

APPENDIX B (NOx and ROG Detailed Emissions Inventory) .......................... 59

LIST OF TABLES

Table 1-1: Imperial County’s population at risk from Ozone exposure ............ 6

Table 2-1: Incorporated Cities in Imperial County (Population)........................ 12

Table 3-1: California and Federal Ambient Air Quality Standards .................... 15

Table 3-2: 8-Hour Ozone Design Values at Each Monitor.................................. 20

Table 4-1: Emissions By Major Source Category 2002 Base Year Summer 

Planning Emissions Inventory (tons/day).......................................... 26

Table 5-1: Stationary Source Control Measures................................................. 31

Table 5-2: CARB Adjustments to the Emissions Inventory Baseline ............... 34

Table 5-3: Regional Transportation Plan Transportation Control Measures 

Project Categories ............................................................................... 38

Table 5-4: Imperial County CEQA Air Quality Handbook Transportation 

Control Measures ................................................................................ 39-40

Table 5-5: CARL Moyer Program Reduction in 2007 (tpy)................................. 41

Table 6-1: CARB Adjustments to the Emissions Inventory Baseline ............... 47

Table 6-2: Motor Vehicle Growth Trends............................................................. 48

Table 6-3: Emissions by Major Source Category 2009 Summer Planning 

Inventory (tons/day)............................................................................. 49

Table 6-4: Imperial County Summer Planning Emissions Inventory 

Comparison.......................................................................................... 49-50

Table 6-5: 2009 Imperial County VOC and NOx Budgets, tons per day............ 51

Table 7-1: State Implementation Plan Checklist................................................. 53-55

LIST OF FIGURES

Figure 3-1: Imperial County Monitoring Site Location....................................... 16

Figure 3-2: Design Values for 2002 to 2009 ........................................................ 19

Figure 3-3: 4

th Highest 8-Hr Averages Per Year 2000 to 2009............................ 20

Figure 4-1: Emissions By Major Source Category: 2002 Base Year – 

Reactive Organic Gases .................................................................... 27

Figure 4-2: Emissions By Major Source Category: 2002 Base Year –

Nitrogen Oxides.................................................................................. 27
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CHAPTER 1 – INTRODUCTION/BACKGROUND Page 1 of 63

CHAPTER 1 

INTRODUCTION/BACKGROUND

1.1 INTRODUCTION

1.2 PURPOSE

1.3 BACKGROUND

1.4 OZONE PRODUCTION AND HEALTH EFFECTS

1.5 REPONSIBILITIES OF AGENCIES
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CHAPTER 1 – INTRODUCTION/BACKGROUND Page 2 of 63

CHAPTER 1 – INTRODUCTION/BACKGROUND

1.1 INTRODUCTION

On July 18, 1997, the United States Environmental Protection Agency (U.S. EPA) 

promulgated an 8-hour ozone National Ambient Air Quality Standard (NAAQS) of 0.080 

parts per million (ppm) in order to promote greater protection of the public health by 

strengthening the already existing 1-hour ozone standard. The new standard, hence 

forth referred to as the 1997 8-hour ozone NAAQS is therefore much more stringent 

than the previous 1-hour ozone standard. With the promulgation of the 1997 8-hour 

ozone NAAQS the U.S. EPA classified the Imperial County as a “Marginal” nonattainment area on April 30, 2004 this was in accordance with the provisions of the 

Clean Air Act (CAA). Subsequently, on February 13, 2008 the U.S. EPA found that the 

Imperial County failed to meet attainment for the 1997 8-hour ozone NAAQS by the 

“Marginal” deadline of June 15, 2007.1 As a result, Imperial County was reclassified as 

a “Moderate” non-attainment area for the 1997 8-hour ozone NAAQS. Those areas 

classified under a “Moderate” classification are required to attain the standard “as 

expeditiously as practicable,” but no later than 6 years after designation or June 15, 

2010. According to the CAA a state must provide for implementation of all control 

measures needed for attainment requiring the submittal of an attainment demonstration, 

a reasonable further progress (RFP) plan, contingency measures along with other 

planning requirements. Therefore, Imperial County was required to develop a revised 

State Implementation Plan (SIP) by December 31, 2008. 

On December 3, 2009 the U.S. EPA issued a final ruling determining that the Imperial 

County “moderate” 8-hour ozone non-attainment area attained the 1997 8-hour NAAQS

for ozone (see Appendix A). The determination by U.S. EPA was based upon 

complete, quality-assured and certified ambient air monitoring data for the years 2006 

thru 2008. This determination effectively suspended the requirement for the state to 

submit an attainment demonstration, a RFP plan, contingency measures and other 

planning requirements for so long as Imperial County continues to attain the 1997 8-

hour ozone NAAQS. However, this determination did not constitute a re-designation to 

attainment under the CAA section 107(d)(3). Therefore, the classification and 

designation status for Imperial County remain as a “moderate” non-attainment area of 

the 1997 8-hour ozone NAAQS. As such, Imperial County is then required to submit for 

U.S. EPA approval a 2009 8-Hour Ozone “Modified” Air Quality Management Plan. 

The 2009 8-Hour Ozone “Modified” Air Quality Management Plan, hence forth referred 

to as the Modified AQMP, is a legal document that fulfills the stipulations contained 

under Title 40 of the Code of Federal Regulations pertaining to the preparation, 

adoption and submittal of Implementation Plans.

Because Imperial County is currently in attainment of the 1997 8-hour ozone NAAQS 

 

1 Determination of Nonattainment and Reclassification of the Imperial County, 8-Hour Ozone Nonattainment Area: 

Federal Register: February 13, 2008 (Volume 73, Number 30)
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CHAPTER 1 – INTRODUCTION/BACKGROUND Page 3 of 63

the Modified AQMP serves as a comprehensive planning document intended to provide 

guidance to the Air Pollution Control District, the County, and other local agencies on 

how to continue maintaining the 1997 8-hour ozone NAAQS.

2

 The Modified AQMP 

must include at a minimum the following moderate area requirements: (1) Nitrogen 

Oxide (NOx) and Volatile Organic Compound (VOC) growth emission inventory, (2) a 

discussion on the implementation of RACT (40 CFR 51.912), and (3) NOx and VOC 

emission offsets of 1.15 to 1 for major source permits (40 CFR 51.165(a)). For a 

complete detailed list of SIP requirements please review the Checklist of SIP 

requirements found in Chapter 7. As a bonus, several of the ozone control measures 

described in the Modified AQMP also reduce PM10 emissions.

1.2 PURPOSE

Clean air is a valuable and essential resource which affects many aspects of our daily 

lives. It is vital to our health and welfare, to the local agricultural economy, and to the 

esthetic beauty and quality of life enjoyed by county residents. Because the capacity of 

the air to absorb environmental contaminants is limited, wise management must be 

practiced in order to avoid significant deterioration of the resource. At its core the CAA 

adopted the NAAQS to protect public health, vegetation, materials and to improve 

visibility. Continued compliance with the NAAQS can only be accomplished by 

developing, adopting and implementing a Modified AQMP that specifically addresses

those issues related to the continued compliance of the 1997 8-hour ozone NAAQS in a 

sound, reasonable and effective manner. 

1.3 BACKGROUND

Since the 1977 amendments to the CAA, areas of the country that violated the NAAQS 

for a particular pollutant were formally designated as non-attainment for that pollutant. 

With the 1990 amendments to the CAA, areas designated as non-attainment for the 1-

hour ozone NAAQS were classified as to the degree of non-attainment status, 

effectively adding a greater degree of accountability upon states. Five classification 

categories were created (§181 of the 1990 CAA). In increasing severity, these were 

marginal, moderate, serious, severe and extreme. Each classification retained a 

different attainment date which would guarantee further protection to the public health 

and welfare. The classification of non-attainment areas is accomplished by the 

determination of a design value.

As mentioned above, with the promulgation of the new ozone standard in June of 1997 

a stricter standard of 0.080 parts per million (ppm) averaged over 8 hours was 

implemented. An exceedance of the 1997 8-hour ozone NAAQS occurs when a monitor 

measures ozone above 0.084 ppm (per the rounding convention). Non-compliance with 

the ozone NAAQS occurs when the calculated design value is greater than or equal to 

0.085 ppm. The design value is calculated by arriving at an average of the annual 

 

2

It is important to note, that Imperial County recorded three (3) years of complete quality assured ambient air quality 

monitoring data for the years 2006, 2007, and 2008 demonstrating attainment of the 1997 8-hour ozone NAAQS.
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fourth highest daily maximum 8-hour ozone value over a three consecutive year period 

per monitor. The highest monitor design value in a non-attainment area determines its 

classification.

1.4 OZONE PRODUCTION AND HEALTH EFFECTS

The intent of the CAA is to provide a level of protection to the nation’s public health and 

the environment. The measurement standard used by U.S. EPA in providing protection 

to the public and environment is known as the NAAQS. Utilizing sections 108 and 109 

of the CAA the U.S. EPA set NAAQS for six criteria pollutants one of which is ozone. 

There are essentially two types of ozone, good ozone which is found in the upper

atmosphere while bad ozone is found at ground level. With the implementation of the 

1997 8-hour ozone NAAQS U.S. EPA intended to protect the public health, including the 

health of "sensitive" populations such as asthmatics, children, and the elderly and to 

protect the public welfare, including protection against visibility impairment, damage to 

animals, crops, vegetation, and buildings. Children are at a higher risk from exposure to 

ozone, since they breathe more air per pound of body weight than adults and because 

children’s respiratory systems are still developing. Children also spend a considerable 

amount of time outdoors during summer and during the start of the school year (May -

September) when the highest ozone levels are recorded. Therefore, lawmakers 

understanding that the availability of scientific information is always changing provided a 

provision in the CAA which requires U.S. EPA to review the latest scientific information 

and standards every five years in order to make recommendations on revisions to the 

NAAQS.

OZONE

Ozone occurs in two layers of the atmosphere. The layer closest to the Earth's surface 

is the troposphere where ground-level ozone is found. Ground-level or “bad” ozone is 

not emitted directly into the air, but is formed by a complex series of chemical reactions 

involving NOx, the result of combustion processes, and reactive organic gases (ROG) in 

the presence of sunlight. Organic gases are also known as VOCs, which include many 

industrial solvents, toluene, xylene and hexane as well as the various hydrocarbons that 

are evaporated from the gasoline used by motor vehicles or emitted through the tailpipe 

following combustion. 

Emissions from industrial facilities and electric utilities, 

motor vehicle exhaust, gasoline vapors, and chemical 

solvents are some of the major sources of NOx and 

VOC.

Bad Ozone. Ground-level or "bad" ozone is an air pollutant that is harmful to the human 

respiratory function and is known to damage crops, trees and other vegetation. It is the
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main ingredient of urban smog. At ground level, ozone is of greatest concern during the 

summer months because strong sunlight and the hot weather result in harmful ozone 

concentrations in the air we breathe. Essentially, its formation is promoted by strong 

sunlight, warm temperatures and winds. High concentrations of ground-level ozone 

tend to be a problem in Imperial County only during the hot summer months when these 

conditions frequently occur. 

Good Ozone. Ozone occurs naturally in the Earth's upper atmosphere - 6 to 30 miles 

above the Earth's surface - where it forms a protective layer that shields us from the 

sun's harmful ultraviolet rays. Manmade chemicals are known to destroy this beneficial 

ozone. An area where the protective "ozone layer" has been significantly depleted-for 

example, over the North or South Pole is sometimes called "the ozone hole.” The United 

States, along with over 180 other countries, recognized the threats posed by ozone 

depletion and in 1987 adopted a treaty called the Montreal Protocol to phase out the 

production and use of ozone-depleting substances. The U.S. EPA has established 

regulations to phase out ozone-depleting chemicals in the United States.

Health Effects. Repeated exposure to ozone pollution may cause permanent damage to 

the lungs. Even when ozone is present in low levels, inhaling it triggers a variety of 

health problems. Although breathing impairment is the primary and most noticeable 

health effect, ozone, can cause chest pains, coughing, nausea, throat irritation, and 

congestion. It can also worsen bronchitis, heart disease, emphysema, and asthma, and 

reduce lung capacity. Asthma is a significant and growing threat to children and adults. 

Ozone can aggravate asthma, causing more asthma attacks, increased use of 

medication, more medical treatment and more frequent visits to hospital emergency 

clinics. Although breathing impairment is the primary and most noticeable health effect, 

symptoms of sore throat, nausea or dizziness, coughing and headaches may occur in 

healthy individuals exposed to high ozone concentrations. If exposure to higher 

concentrations is of limited duration, most people can recover to their previous 

functioning level. However, recent studies have shown that routine exposure to lower 

concentrations of ozone can cause chronic lung damage in children, with permanent 

reductions in lung capacity of up to 50% measured.

Healthy people also experience difficulty in breathing when exposed to ozone pollution. 

Because ozone pollution usually forms in hot weather, anyone who spends time 

outdoors in the summer may be affected, particularly children, the elderly, outdoor 

workers and people exercising outdoors. Children are most at risk from exposure to 

ozone because they are active outside, playing and exercising, during the summertime 

when ozone levels are at their highest. Table 1-1 presents Imperial County’s population 

at risk from ozone exposure as of 2005 population.
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CHAPTER 1 – INTRODUCTION/BACKGROUND Page 6 of 63

*Table 1-1

Imperial County’s population at risk from Ozone exposure 

GROUPS AT RISK POPULATION

Pediatric Asthma: 4,389

Adult Asthma: 8,365

Chronic Bronchitis: 4,614

Emphysema: 1,844

Cardiovascular Disease: 34,768

Diabetes: 7,963

Total Population: 160,301

Population Under 18: 47,295

Population 65 & Over: 16,478

 *Table 1-1: 2005 Information provided by American Lung Association. 

www.stateoftheair.org/2008/states/california/imperial-06025.html

Environmental Effects. Ground-level ozone damages plant life and is responsible for an 

estimated 500 million dollars in reduced crop production in the United States each year. 

Ozone interferes with the ability of plants to produce and store food, making them more 

susceptible to disease, insects, other pollutants, and harsh weather. It damages the 

foliage of trees and other plants, ruining the landscapes of cities, parks and forests, and 

recreation areas.

Ozone is also considered a serious threat to California agriculture and native vegetation 

due to its pervasive nature. Many sensitive plant species are known to suffer damage at 

concentrations below human health standards. Ozone interferes with photosynthesis by 

attacking leaves, causing them to yellow, develop dead areas and drop leaves early. 

Ozone stunts growth in many crop varieties, reduces yields, or causes esthetic damage 

which lowers market value. Many of the crops grown within this county are particularly 

sensitive to ozone injury, including orchard crops, lettuce and several other varieties of 

vegetation.

1.5 RESPONSIBILITIES OF AGENCIES

Agencies with direct and indirect interest in air quality which participate in the planning 

process as it pertains to the CAA are discussed below.

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY (U.S. EPA)

The U.S. EPA administers the CAA and other air quality related legislation. As a 

regulatory agency, U.S. EPA responsibilities include establishing national emission 

limits for major sources of air pollution; inspecting and monitoring emission sources, 

enforcing federal air quality laws, promulgating new regulations, providing financial and 

technical support for air quality research and development programs, setting NAAQS 

and preparing guidance for and action on SIP’s to meet and/or maintain those NAAQS. 

Essentially, the U.S. EPA is required to take action on the California SIP. The California 
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SIP is comprised of plans developed at the regional or local level. Each of these plans is 

individually reviewed and approved by U.S. EPA prior to incorporation into the SIP

The U.S. EPA says that 146 million Americans live in counties where monitored air in 

2002 was unhealthy because of high levels of principal air pollutants; that more than 

160 million tons per year of emissions of criteria air pollutants were emitted into the air 

by cars, trucks, industrial facilities and utilities, small businesses and other sources; and 

that 124 metropolitan areas are still considered "non-attainment" for one of the six 

pollutants targeted by the CAA. Since the 1990 Amendments to the CAA which 

instituted the classification process, there has been a vast improvement in the amount 

of emissions of criteria pollutants compared to 1970.

Clean Air Act Amendments of 1990 (CAA)

Anticipated economic impacts were the primary component in the debate over the 1990

Amendments to the CAA which included the strengthening of the ozone and particulate 

matter (PM) standards. Still, the CAA and new federal and state regulations are creating 

new markets for alternative fuels, pollution control equipment, and new services. 

Supporters believe that the economic value public-health benefits resulting from the 

CAA can be measured in fewer sick days, hospitalizations, and deaths which more than 

offset initial economic costs.

U.S. EPA is required to do the following:

1. The U.S. EPA will provide technical assistance to the state and local area in the 

development of an attainment plan.

2. The U.S. EPA will move quickly to review and act on completed plans after 

submission of any revision to the SIP by the state.

3. Provided that the monitors in the area reflect attainment by the due date and the 

area submits an approvable maintenance plan and re-designation request, the 

U.S. EPA will move expeditiously to re-designate the area as attainment and 

impose no additional requirements.

The 1990 Amendments also established a local air quality planning process, requiring 

SIP’s for each local area that had not attained a particular standard. These plans are to 

be prepared by local agencies and are to be incorporated into the SIP. The U.S. EPA 

was given power to impose sanctions for failure to submit a plan or carry out 

commitments in a plan. Sanctions could include offset sanctions and the withholding of 

federal highway funds. 

CALIFORNIA AIR RESOURCES BOARD (CARB)

The California Air Resources Board (CARB) is the state agency responsible for the 

coordination and administration of both state and federal air pollution control programs 
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in California. The CARB undertakes research, sets state ambient air quality standards

(CAAQS), provides technical assistance to local Air Pollution Control Districts, compiles 

emission inventories, develops suggested control measures, and provides oversight of 

Air Pollution Control District control programs.

A key function of CARB is to coordinate and guide regional and local air quality planning 

efforts required by the California Clean Air Act (CCAA), and to prepare and submit

required SIP’s to U.S. EPA. CARB also establishes emission standards for motor 

vehicles. The CAA allows California to adopt more stringent vehicle emission standards 

than the rest of the nation due to California’s severe air pollution problem. 

IMPERIAL COUNTY AIR POLLUTION CONTROL DISTRICT (ICAPCD)

The Imperial County Air Pollution Control District (ICAPCD) shares responsibility with 

CARB for ensuring that all state and federal ambient air quality standards are achieved 

and maintained within the County. State law assigns to local Air Pollution Control 

Districts the primary responsibility for control of air pollution from stationary sources, 

while reserving an oversight role for CARB. Generally, the Air Pollution Control Districts 

must meet minimum state and U.S. EPA program requirements. The Air Pollution 

Control District is also responsible for the inspection of stationary sources, monitoring of 

ambient air quality, and planning activities such as modeling and maintenance of the 

emissions inventory. As it pertains to this Modified AQMP the ICAPCD will:

1. Maintain the NOx and VOC growth emission inventory

2. Provide a discussion on the implementation of RACT (40 CFR 51.912)

3. Provide NOx and VOC emission offsets of 1.15 to 1 for major source permits (40 

CFR 51.165(a)).
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CHAPTER 2 

PLANNING AREA

2.1 PHYSICAL DESCRIPTION OF THE PLANNING AREA

2.2 CLIMATE

2.3 ATMOSPHERIC STABILITY AND DISPERSION

2.4 LAND USE

2.5 POPULATION
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CHAPTER 2 – PLANNING AREA

2.1 PHYSICAL DESCRIPTION OF THE PLANNING AREA

Geographical Description

Imperial County extends over 4,482 square miles in the southeastern corner of 

California. It is bordered on the south by Mexico, on the east by Arizona, on the west 

by the Coyote and Fish Creek Mountains (which are in San Diego County), and on the 

north by Riverside County. The Salton Trough runs approximately northwest-southeast 

through the center of the county and extends into Mexico. The elevation in Imperial 

County ranges from about 230 feet below sea level in the Salton Sea to the north to 

more than 2800 feet on the mountain summits to the east. 

2.2 CLIMATE

Winters are mild and dry with daily average temperature ranges between 65 and 75oF 

(18-24oC). During winter months it is not uncommon to record maximum temperatures 

of up to 80oF. Summers are extremely hot with daily average temperature ranges 

between 104 and 115oF (40-46oC). It is not uncommon, during summer months, to 

record maximum temperatures of 120oF. The annual rainfall is just over 3 inches (7.5 

cm) with most of it coming in late summer or midwinter. 

Climatic conditions in the Imperial County are governed by the large-scale sinking and 

warming of air in the semi-permanent tropical high pressure center of the Pacific 

Ocean. The high pressure ridge blocks out most mid-latitude storms except in winter 

when the high is weakest and farthest south. The coastal mountains prevent the 

intrusion of any cool, damp air found in California coastal environs. Because of the 

weakened storms and barrier, the Imperial County experiences clear skies, extremely 

hot summers, mild winters, and little rainfall. The flat terrain of the valley and the strong 

temperature differentials created by intense solar heating, produce moderate winds 

and deep thermal convection. 

The combination of subsiding air, protective mountains and distance from the ocean all 

combine to severely limit precipitation. Rainfall is highly variable with precipitation from 

a single heavy storm exceeding the entire annual total during a later drought condition. 

The Imperial County enjoys a year-round climate characterized by a temperate fall, 

winter and spring and a harsh summer. Humidity often combines with the valley's 

normal high temperatures to produce a moist, tropical atmosphere that frequently 

seems hotter than the thermometer suggests. The sun shines, on the average, more in 

the Imperial County that anywhere else in the United States. 

2.2.1 Humidity

Humidity is low throughout the year, ranging from 28 percent in summer to 52 percent in 

winter. The large daily oscillation of temperature produces a corresponding large 
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variation in the relative humidity. Nocturnal humidity rises to 50-60 percent, but drop to 

about 10 percent during the day. Summer weather patterns are dominated by intense 

heat induced low-pressure areas that form over the interior desert. 

2.2.2 Typical Weather Patterns 

The wind direction follows two general patterns. The prevailing winds are from the west 

and northwest seasonally from fall through spring. These originating prevailing winds 

are known to be from the Los Angeles area. 

Occasionally Imperial County experiences periods of extremely high winds speeds. 

Wind speeds can exceed 31 mph occurring most frequently during the months of April 

and May. However, speeds of less than 6.8 mph account for more than one-half of the 

observed wind measurements. Wind statistics indicate prevailing winds are from the 

west-northwest through southwest; a secondary flow maximum from the southeast is 

also evident.

2.3 ATMOSPHERIC STABILITY AND DISPERSION

Air pollutant concentrations are primarily determined by the amount of pollutant 

emissions in an area and the degree to which these pollutants are dispersed in the 

atmosphere. The stability of the atmosphere is one of the key factors affecting pollutant 

dispersion. Atmospheric stability regulates the amount of vertical and horizontal air 

exchange, or mixing, that can occur within a given air basin. Restricted mixing and low 

wind speeds are generally associated with a high degree of stability in the atmosphere. 

These conditions are characteristic of temperature inversions.

In the atmosphere, air temperatures normally decrease as altitude increases. At varying 

distances above the earth's surface, however, a reversal of this gradient can occur. This 

condition, termed an inversion, is simply a warm layer of air above a layer of cooler air, 

and it has the effect of limiting the vertical dispersion of pollutants. The height of the 

inversion determines the size of the mixing volume trapped below. Inversion strength or 

intensity is measured by the thickness of the layer and the difference in temperature 

between the base and the top of the inversion. The strength of the inversion determines 

how easily it can be broken by winds or solar heating. 

Imperial County experiences surface inversions almost every day of the year. Due to 

strong surface heating, these inversions are usually broken allowing pollutants to be 

more easily dispersed. Weak, surface inversions are caused by radiational cooling of air 

in contact with the cold surface of the earth at night. In valleys and low lying areas this 

condition is intensified by the addition of cold air flowing down slope from the hills and 

pooling on the valley floor.

The presence of the Pacific high pressure cell can cause the air to warm to a 

temperature higher than the air below. This highly stable atmospheric condition, termed 

a subsidence inversion can act as a nearly impenetrable lid to the vertical mixing of 
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pollutants. The strength of these inversions makes them difficult to disrupt. 

Consequently, they can persist for one or more days, causing air stagnation and the 

buildup of pollutants. Highest or worst-case ozone levels are often associated with the 

presence of this type of inversion.

2.4 LAND USE

Since 1990, Imperial County's $1.6 billion dollar agricultural industry grew over 52% in 

2008. Vegetable and melon crops led the county tally, grossing more than $675 million 

followed by field crops (hay) which grossed $482 million. More than 40 types of crops 

and commodities are grown in the Imperial County. This ranks Imperial County tenth 

among all California counties, and twelfth among all counties in the United States. 

Approximately one half a million acres of land are farmed in Imperial County and the 

total farmable acres have remained fairly constant over the past decade. During the 

high season, approximately 25% of Imperial County’s labor force work in the Agricultural 

Sector. Additionally, Imperial County has more acreage and production of alfalfa than 

any other county in the United States. It is also a major producer of lettuce, feedlot beef, 

melons, carrots, Sudan grass hay, onions and numerous other commodities.

2.5 POPULATION

Growth has been a central part of local discussion for the past few years in the Imperial 

County. Table 2-1 below shows the population estimates for the larger incorporated 

areas in Imperial County. In addition, the category “Balance of County” identifies the 

population estimates for the cities of Bombay Beach, Desert Shores, Heber, Niland, 

Ocotillo, Palo Verde, Salton City, Salton Sea Beach, Seeley, and Winterhaven. The 

increase in population is evident when one compares the populations for 1990 and 

2007. Between 1990 and 2007 Imperial County increased its population by 62,200 new 

residents. 

Table 2-1

* There are seven incorporated cities in Imperial County

IMPERIAL COUNTY 1990 2000 2001 2002 2003 2004 2005 2006 2007

Brawley 18,923 22,052 22,365 22,497 22,731 23,402 23,915 25,426 25,522

Calexico 18,633 27,109 28,049 29,783 32,014 34,256 36,079 36,651 37,295

Calipatria 2,690 7,289 7,280 7,612 7,651 7,791 7,884 7,819 7,750

El Centro 31,405 38,025 38,476 38,738 39,359 39,862 40,817 41,904 41,789

Holtville 4,820 5,612 5,674 5,694 5,710 5,726 5,715 5,832 6,257

Imperial 4,113 7,560 7,766 8,112 8,524 9,281 9,516 10,116 11,772

Westmorland 1,380 2,131 2,175 2,195 2,201 2,210 2,430 2,368 2,359

Balance of County 27,339 32,583 32,977 33,118 33,625 33,870 34,733 36,116 38,832

County Total 109,303 142,361 144,762 147,749 151,815 156,398 161,089 166,232 171,576

*Information provided by the Department of finance at www.dof.ca.gov
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CHAPTER 3 – EXISTING AIR QUALITY Page 13 of 63

CHAPTER 3 

EXISTING AIR QUALITY

3.1 AIR QUALITY STANDARDS

3.2 AIR QUALITY MONITORING

3.3 LOCAL OZONE MEASUREMENTS
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CHAPTER 3 - EXISTING AIR QUALITY

3.1 AIR QUALITY STANDARDS

In 1970 Congress simultaneously created the U.S. EPA and passed the CAA creating a 

national campaign to maintain healthy air quality standards for the control of air 

pollution. The CAA was subsequently amended in 1990 which intensified the national 

air quality control efforts to clean up air pollution in the United States. The provisions 

within the 1990 amendments included the NAAQS for six common air pollutants, State 

attainment plans, vehicle emission standards, stationary source emission standards, 

permits, and enforcement provisions.

The U.S. EPA established the NAAQS which identify the impact to humans and to the 

environment. The primary standard is designated to protect human health while the 

secondary standard is designated to protect the public welfare and the environment. 

The CAA requires not only that the U.S. EPA establish the NAAQS but that the U.S. 

EPA periodically review and amend those standards as needed. 

Over the past several decades, the federal government has set and periodically revised 

the NAAQS for pollutants that are of the greatest public health concern. These 

standards encompass the most common varieties of airborne materials which can pose 

a health hazard. The NAAQS is expressed as a measure of the amount of pollutant per 

unit of air. Because these pollutants are found all over the United States tribal, state and 

local governments must comply with the CAA by meeting the NAAQS. As a 

consequence, pollutants with ambient standards remain the chief focus of air quality 

management activities around the nation.

At the state and national level, the process of setting standards involves careful review 

of scientific studies which relate pollutant concentrations to public health and welfare. 

These studies are used to establish the criteria on which the standards are based. Air 

quality standards are typically set at levels which provide a reasonable margin of safety 

and protect the health of the most sensitive individuals in the population. Pollutants for 

which ambient standards have been established based on the criteria studies 

mentioned above are known as 'criteria pollutants'. Criteria pollutants include ozone, 

carbon monoxide, nitrogen dioxide, sulfur dioxide, PM10 (a general category of airborne 

particles 10 microns or less in diameter), PM2.5 a specific particulate matter, and lead. 

Different standards for these and other pollutants have been set by the federal and the 

California governments. California standards tend to be more restrictive than national 

standards.

The California Clean Air Act (CCAA) requires Air Pollution Control Districts to use the 

more restrictive State standards when setting up new source review limits to achieve no 

net increase. In addition, State law requires all Districts that cannot demonstrate 

attainment of the State ozone standard to adopt all feasible measures to reduce ROG

and NOx, the precursors to ozone. Beyond the tighter standards for the criteria 

pollutants listed below, California has also set standards for sulfates, hydrogen sulfide, 
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vinyl chloride, and visibility-reducing particles. The ambient air quality standards for 

each of these pollutants are shown in Table 3-1.

Table 3-1 California and Federal Ambient Air Quality Standards

Pollutant Averaging Times California Standards Federal Standards

Concentration Primary Secondary

Carbon Monoxide

8-hour 9 ppm 

(+10 mg/m3)

9 ppm 

(10 mg/m3) None

1-hour 20 ppm 

(23 mg/m3)

35 ppm 

(40 mg/m3) None

Lead 30 Day-Average 1.5 μg/m3 --- ---

Quarterly Average --- 1.5 μg/m3 Same as Primary

Nitrogen Dioxide Annual (Arithmetic Mean) 0.030 ppm 

(56 μg/m3)

0.053 ppm 

(100 μg/m3) Same as Primary

1-hour 0.18 ppm (338 μg/m3) --- ---

Particulate Matter 

(PM10)

Annual (Arithmetic Mean) 20 μg/m3 Revoked Revoked

24-hour 50 μg/m3 150 μg/m3 Same as Primary

Particulate Matter 

(PM2.5)

Annual (Arithmetic Mean) 12.0 μg/m3 15.0 μg/m3 Same as Primary

24-hour --- 35 μg/m3 Same as Primary

Ozone

8-hour 0.07 ppm (137 μg/m3

) 0.08 ppm * Same as Primary

1-hour 0.09 ppm (180 μg/m3) --- Same as Primary

Sulfur Dioxide (SO2)

Annual (Arithmetic Mean) --- 0.03 ppm (80 μg/m3) ----

24-hour 0.04 ppm (105 μg/m3) 0.14 ppm (365 μg/m3) ---

3-hour ------- --- 0.5 ppm 

(1300 μg/m3)

1-hour 0.25 ppm (655 μg/m3) --- ---

*On January 19, 2010 the U.S. EPA filed a proposal to reconsider the existing ozone standard to a level of 0.060 to 0.070 ppm. 

3.2 AIR QUALITY MONITORING

Imperial County began its ambient air monitoring in 1976; however, monitoring of ozone 

began in 1986 at the El Centro monitoring station. Since that time, monitoring has been 

performed by the ICAPCD, CARB and private industry. Ambient monitoring is typically 

performed either in locations representative of where people live and work. Air 

monitoring is performed to meet many objectives. These include determining 

compliance with air quality standards, identifying areas with the highest pollutant 

concentrations, evaluating pollutant transport, and as the basis of daily reports to the 

public in newspapers and television about air quality levels.

For most pollutants, continuous monitoring occurs 24 hours a day, usually for periods of 

many years at one location. Because of many years of continual monitoring, a baseline 

level has been established allowing for trends and progress towards air quality goals to 

be identified. Air monitoring demands close attention by experienced technicians. 

Stringent quality assurance procedures for instrument operation and data validation are 

followed before monitoring data is included into the county's air quality record. The 

monitoring network in this county has slowly but steadily expanded over the years, with 

total operational cost now estimated to exceed $ 100,000 annually. 

The Imperial County ground level ozone is measured at 6 monitoring stations 

throughout the County: Calexico East, Calexico Ethel Street, El Centro, Brawley, 
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Westmorland, and Niland. Figure 3-1 shows the location of the six monitoring stations 

currently in operation in Imperial County. 

In addition to the Imperial County monitoring stations, three ozone monitoring stations 

have similarly been located in Mexicali, Baja California, Mexico. This reflects the 

cooperative efforts between the US Government and that of the Mexican Government in 

attempting to clean the air in both Mexicali and Imperial County. These stations were 

established to help identify cross-border transport of pollutants and associated pollutant 

precursors. 

Air Quality measurements are collected and stored in a comprehensive air quality data 

base maintained by U.S. EPA. In addition, CARB maintains a comprehensive air quality 

database that can be accessed through CARB’s webpage. Monitoring instruments and 

resulting data are routinely reviewed and audited by the CARB to ensure the integrity of 

the data. The data from these monitoring stations can also help to identify cross-border 

transport of pollutants and associated pollutant precursors.

*Figure 3-1

Imperial County Monitoring Site Location

*W. First Street is the nearest cross street for Westmorland

Calexico-East – The Calexico East monitoring station, run and maintained by the 

CARB, was installed in 1996. Located above sea level the absolute location is latitude 

32° 40’ 27” and longitude 115° 23’ 28”. Its relative location is north of the U.S. – Mexico 

border in close vicinity to the Highway 7 Calexico/Mexicali checkpoint border crossing. 

The site currently records measurements for ozone (O3), CO, NO2, SO2, and PM2.5, as 

well as surface wind speed and wind direction. 
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Calexico-Ethel/Belcher – The Calexico Belcher monitoring station formerly known as 

the Ethel monitoring station, run and maintained by the CARB, was installed in 1994. 

Located above sea level it has an absolute location of latitude 32° 40’ 34” and longitude 

115° 28’ 59”. Its relative location is 1029 Belcher Street within the property boundary on 

the Southeast corner of the Calexico High School football field parking lot. To the north 

is located an athletic sports field used for football, baseball and track. The monitoring 

station is surrounded by a suburban neighborhood directly to the south, southeast and 

southwest. Relative to the international border crossing the monitoring station is 

approximately 1.2 km directly north. The site is recording measurements for ozone 

(O3), CO, NO2, SO2, PM2.5, PM10, lead and toxics.

Calexico-Grant - The Calexico Grant monitoring station was installed in 1991 and its 

operation was discontinued in 2007. Located at sea level the Calexico Grant station 

had an absolute location of latitude 32° 40’ 26” and longitude 115° 30’ 59”. Its relative 

location was 900 Grant Street, at the southwestern portion of the city of Calexico. 

Located behind the local City Fire Department the Calexico Grant monitoring station 

was surrounded by a suburban neighborhood directly to the south, east and west. 

Farther to the South past the residences and skate park there lies the New River 

(approximately 0.2 km South), the Calexico International Airport (approximately 0.8 km 

South, Anza Road (slightly over 0.8 km South), and the International border to Mexico 

(approximately 1.2 km South.) Approximately 1.2 km to the Southeast of the monitoring 

station is a large (5 acre) unpaved lot on Anza Road that lies about 0.4 km from 

customs, on the U.S. side of the border the Calexico-Grant site recorded measurements 

of ozone and PM10.

El Centro - The El Centro monitoring station was installed in 1986. Located above sea 

level its absolute location is latitude 32° 47’ 32” and longitude 115°33’ 47”. Its relative 

location is 150 South 9th Street on the roof of the ICAPCD building. The monitoring 

station is surrounded by governmental and commercial buildings. It is the first 

monitoring site north of the City of Calexico creating the south to north monitoring 

network for Imperial County. The El Centro monitoring station is classified as urban 

with large agricultural areas to the East and West of the city’s boundaries. This site 

records measurements for ozone (O3), CO, NO2, PM2.5, and PM10.

Brawley - The current Brawley monitoring station which was installed in 2003 as a new 

station replacing the old Brawley monitoring station installed in 1982 is located below 

sea level and has an absolute location of latitude 32° 58’ 42” and longitude 115° 32’ 21”. 

Its relative location is 220 Main Street atop the Imperial County courthouse in the middle 

of the city of Brawley surrounded by commercial buildings. Like other cities within 

Imperial County the City of Brawley is surrounded by agricultural lands to the east, north 

and the west. The Brawley station is the third furthest northerly station within the 

Imperial County monitoring network. This site records measurements for PM2.5, and 

PM10.

Westmorland - The Westmorland monitoring station which was installed in 1994 

commenced measuring ozone in 1998. Located below sea level its absolute location is 
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latitude 33° 1’ 57” and longitude 115° 37’ 25”. Its relative location is 570 Cook Street in 

Westmorland. The site is the fourth most northerly station within the Imperial County 

monitoring network. It lies west of Brawley but southwest of Niland. Residential and 

agricultural areas lie within 10m and 400m of the site. The site records both ozone (O3) 

and PM10 concentrations using a sampling inlet that is approximately 5m above ground 

level. 

Niland - The Niland monitoring station was installed in 1996 and commenced 

measuring ozone in 1997. Located below sea level its absolute location is latitude 33° 

12’ 49” and longitude 115° 32’ 43”. Its relative location is 7711 English road. It is 

adjacent to English Road which is an unpaved and lightly travelled road (approximately 

100 vehicles per day). The monitoring site is surrounded by agricultural land to the 

south, southwest and southeast. A single residence exists to the west of the station 

across English Road. The monitoring station is southeast of the Salton Sea and 

Riverside County. The Niland monitoring station is the most northerly site within the 

Imperial County monitoring network. The site records measurements for ozone (O3) 

and PM10.

3.3 LOCAL OZONE MEASUREMENTS

Typically, pollutant levels at any one location vary widely over time. As a result, air 

monitoring produces highly diverse data sets which are difficult to characterize with a 

few simple numbers. Statistical descriptors of air quality data can range from simple 

averages and highest values to more involved indicators. The simplest measure, cited 

in the narrative below, is to note the highest levels observed at different locations each 

year. Maximum and average values are useful for evaluating compliance with 

established air quality standards and for defining the time periods when highest 

pollutant concentrations are most likely to occur. As such, they characterize only the 

most adverse air quality conditions measured during the year and are not representative 

of more commonly occurring pollutant levels.

Due to the extensive and complicated nature of an exhaustive evaluation of the criteria 

pollutants monitored in Imperial County, this section evaluates only the most recent 

ozone data collected by our monitors and associated trends of compliance with the 

NAAQS.

Air quality trend analysis is important in assessing pollutant levels, and is particularly 

useful for planning purposes. Trends are evaluated in this analysis using two indicators 

of local ozone levels: the 4th highest 8-hour average concentration measured each year 

and the design value for each year.

According to the U.S. EPA regulation, 40 CFR part 50, the primary and secondary 1997 

8-hour ozone standard is met when a given 3-year average of an annual fourth highest 

daily maximum 8-hour average ambient air quality ozone concentration is less than or 

equal to 0.08 ppm (i.e., 0.084 ppm when rounding is considered). Simply put, ozone is 

measured hourly, known as hourly measurements at each monitoring site. From the 
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hourly measurements, 8-hour averages are calculated per hour and per monitoring site. 

At each site, the highest daily 8-hour average is identified and recorded as the 

maximum 8-hour concentration for that day. Thus, for any given single year the fourth 

highest daily maximum 8-hour average is identified and averaged over three years per 

site. This 3-year average is referred to as the design value. When the design value is 

less than or equal to 0.084 ppm at each monitor within the area, then the area is 

meeting the NAAQS (see Figure 3-2).

In addition, ambient air quality monitoring data for the 3-year period must meet a data 

completeness requirement. The ambient air quality monitoring data completeness 

requirement is met when the average percent of days with valid ambient monitoring 

data is greater than 90 percent, and no single year has less than 75 percent of data 

completeness as determined in Appendix I of part 50.

Despite an approximate growth of 39.5% in the Imperial County, Air quality, as it 

pertains to ozone, has improved greatly in this region in recent years. Figure 3-3

demonstrates how the Imperial County’s air quality has improved dramatically since 

2002, the base year for the 2009 Modified AQMP. As mentioned in Chapter 1 the U.S. 

EPA made a determination based on the 2006-2008 monitoring data that the Imperial 

County moderate 8-hour ozone nonattainment area attained the 1997 8-hour NAAQS. 

To illustrate the downward trend in ozone concentrations, Figure 3-3 shows the Highest 

4th 8-hour average concentrations for the years 2000 thru 2009.

0.040

0.045

0.050

0.055

0.060

0.065

0.070

0.075

0.080

0.085

0.090

0.095

0.100

2002 2003 2004 2005 2006 2007 2008 2009

Parts Per Million

YEAR

Figure 3-2 Design Values for Each Year

Clx - East

Clx - Ethel

El Centro

Westmorland

Niland
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To further substantiate the progress towards attainment the ICAPCD ozone design 

value was at 30% above the standard more than 10 years ago (1995). Since that time 

ozone air quality has continued to improve and most recently in 2007 the design value 

was less than 10% above the standard culminating in attainment with the 1997 8-Hour 

ozone NAAQS in 2008. 

Table 3-2 shows 8-hour Ozone design values per year for each monitoring station. It 

also demonstrates attainment of the 1997 8-Hour NAAQS for the Imperial County. 

Table 3-2. 8-hour Ozone Design Values at Each Monitor

Year

Air Monitoring Stations

Calexico 

Ethel

Calexico 

East

El Centro Westmorland Niland

2000 0.088 0.075 NED NED NED

2001 0.100 0.092 0.083 0.068 0.079

2002 0.087 0.084 NED NED NED

2003 0.078 0.084 0.087 0.069 0.079

2004 0.068 0.078 0.085 0.073 0.078

2005 0.071 0.075 0.084 0.079 0.072

2006 0.074 0.076 0.085 0.085 0.073

2007 0.079 0.790 0.086 0.087 0.074

2008 0.080 0.079 0.082 0.082 0.075

2009 0.083 0.076 0.079 0.080 0.077

Note: NED indicates that either a monitor was not established or validated data was incomplete

0.000

0.020

0.040

0.060

0.080

0.100

0.120

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

Parts Per Million

Year

Figure 3-3 4th Highest 8 Hr Averages per Year

2000 to 2009

Calexico - East

Calexico - Ethel

El Centro

Niland

Westmorland
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CHAPTER 4

EMISSION INVENTORY

4.1 INTRODUCTION

4.2 EMISSION SOURCE CLASSIFICATION SYSTEM

4.3 2002 BASELINE INVENTORY CATEGORIES
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CHAPTER 4 - EMISSION INVENTORY

4.1 INTRODUCTION

An emissions inventory identifies the sources of air pollution in a given region and 

quantifies their emissions. Inventories are used to track emission levels over 

designated time periods in order to help with the planning process in a given region or 

area. Inventories allow for the understanding of current emissions levels and the 

projection of future emission levels. Effective control strategies cannot be developed 

without an understanding of the type and number of emission sources contributing to 

the air quality problem. This chapter describes the inventory and discusses how it is 

developed, while chapter 6 discusses how the baseline inventory is used to project 

inventories for future years. 

In cooperation with CARB, the ICAPCD develops a complete emissions inventory every 

year for all sources in Imperial County. This chapter presents emissions that occurred 

in Imperial County during the base year 2002. The U.S. EPA designates the 2002 

inventory as the baseline for measuring progress toward attainment of the 8-hour ozone 

NAAQS. Thus, a significant effort has gone into making this inventory as complete and 

as accurate as possible. The pollutants included in the emissions inventory are reactive 

organic compounds (ROG) and oxides of nitrogen (NOx), both precursors to ozone 

formation.

The emissions from many types of sources change by season, time of day, or even day 

of the week, either because of changes in the activity level (usage or throughput) or in 

the emission rate. For example, passenger cars tend to be used more in the summer 

than in the winter because there are more daylight hours and more people are traveling. 

Drivers are more likely to use air conditioners during the summer months while higher 

outdoor temperatures also increase the rate at which fuel evaporates from cars. 

Emissions from the passenger vehicle category are higher in the summer than in the 

winter because both the activity levels and emission rates are higher.

Any strategy designed to mitigate air pollution in the Imperial County must consider this 

seasonal variation in ambient air quality. The Modified AQMP uses the “summer 

planning inventory,” which is a better representation of emissions because emissions 

which occur from May through October are when exceedances of the standard are 

more likely to occur. The 2002 summer planning inventory reports emissions in units of 

tons per day (tpd) and includes data for the pollutants ROG and NOx, the two 

precursors to ozone (Table 4-1). Although the summer planning inventory forms the 

basis for maintaining compliance with the 1997 8-hour ozone NAAQS and provides the 

basis for the emissions reduction strategies presented in Chapter 5 it is part of an 

overall emissions inventory assembled and maintained by CARB in the California 

Emission Inventory Development and Reporting System (CEIDARS) and the California 

Emission Forecasting and Planning Inventory System (CEFS).
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4.2 EMISSION SOURCE CLASSIFICATION SYSTEM

All reportable sources are categorized as either stationary or mobile. Stationary source 

categories are subdivided into point and area-wide sources, depending primarily on 

their permit status, relative size and emission characteristics while mobile source 

categories are subdivided into on-road and off-road.

Stationary Sources

Point sources are generally larger commercial or industrial facilities that are required to 

have a District Permit to Operate. The point source category includes facilities such as 

factories, geothermal plants, rock quarries, and farming operations.

Area-Wide Sources

The area-wide category includes aggregate point sources or facilities that are not 

inventoried individually, but are estimated as a group and reported as a single source 

category. These sources consist of categories associated with human activity and 

emissions that take place over a wide geographic area. Examples include pesticides, 

consumer products, and residential fuel combustion.

Mobile Sources 

Mobile source categories consist of two subcategories: on-road and off-road. On-road 

sources include passenger cars, school buses, and trucks. CARB’s most recent mobile 

source Emission Factors model, EMFAC2007, is used to calculate emission rates from 

all motor vehicles, such as passenger cars to heavy-duty trucks, operating on highways, 

freeways and local roads in California. EMFAC2007 uses Department of Motor Vehicle 

(DMV) registration data for the number of vehicles, Southern California Association of 

Governments (SCAG) travel demand output model for the number of vehicle miles 

traveled, Bureau of Automotive Repair (BAR) odometer readings and emission factors 

from vehicle surveillance programs and dynamometer readings.

Off-road sources are generally regulated at the state or federal level and consist of 

aircrafts, trains, and off-road recreational vehicles. The off-road emissions inventory is 

generated by the CARB OFFROAD Model, which uses source population, activity, and 

emissions data to estimate emissions for each type of off-road equipment. The model 

provides emission estimates for all off-road vehicles, including boats, outdoor 

recreational vehicles, industrial and construction equipment, farm equipment, lawn and 

garden equipment, aircraft, and trains.

4.3 2002 BASELINE INVENTORY CATEGORIES

This section provides a brief description of the major emission inventory categories. The 

major sources are grouped according to either the stationary source or mobile source 

category. Within each category, the sources are further classified according to the 
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appropriate activity, such as the burning of fuel or the processing of petroleum. 

However, it is not uncommon to find different source types at the same facility. Thus, an 

individual company’s emission inventory may be divided among two or more source 

categories. The major source category discussion and tables are based on the 

emissions inventory data obtained from the summer planning emissions inventory.

Table 4-1 summarizes the 2002 planning emissions inventory by major source 

categories. A detailed breakdown of NOx and ROG emissions from 2002 through 2023 

by source category is presented in Appendix B. The baseline inventory, including future 

year projections, reflects the regulations adopted as of December 31, 2006. A listing of 

ICAPCD and CARB rules and regulations that are reflected in the baseline inventory 

can be found in Chapter 5.

Fuel Combustion: This category includes sources that burn fuel such as natural gas 

and diesel as a matter of operations or to produce useful heat. Combustion processes 

are a significant source of NOx emissions due to the oxidation of nitrogen in the fuel and 

in the combustion of air. Examples of sources in this category are electric utility boilers, 

process heaters, internal combustion engines, home furnaces, and orchard heaters. 

Emissions from this source category represent 9.5% of the NOx emissions and 0.32% 

of the ROG emissions in the 2002 summer planning emissions inventory.

Managed Burning and Disposal: The emission inventory data for this activity is reported 

in the Miscellaneous Processes source category. The burning of agricultural waste can 

generate considerable quantities of ROG, CO and PM10 because of the incomplete 

combustion process. Reports indicate that the majority of the reported emissions are a 

result of the open burning of wheat straw and Bermuda grass. Other sources 

represented in this category include residential burning, open burning of agricultural and 

residential tree pruning, and range improvement burns. Waste burning generates 

approximately 2.32 tpd or 6.2% of the ROG emissions in the summer planning 

emissions inventory.

Solvent Use: Organic solvents are used in a wide variety of industrial processes and 

are ingredients in numerous household and commercial products. The major concern 

here is that most solvents volatilize as ROG, which then becomes available to form 

ozone Example categories are dry cleaning, degreasing, asphalt paving, architectural 

coatings, and printing operations. These sources are responsible for approximately 

24.14% of the ROG emissions in the summer planning emissions inventory.

Petroleum Production and Marketing: Emissions represented in this category result 

from the petroleum industry (petroleum pumping stations, truck loading and unloading.) 

Other activities include retail and commercial gasoline marketing and combustion 

related emissions that do not qualify for the Fuel Combustion category above. This 

source category accounts for 1.7% of the ROG emissions in the 2002 summer planning 

inventory.

Industrial Processes: The sources and activities included here primarily emit PM10 and 
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ROG. Examples are feed and grain mills, rock quarries, sand and gravel operations, 

and concrete batch plants. The ROG emissions from this group of sources represent 

approximately 0.2% of the ROG emissions in the 2002 summer planning emissions 

inventory.

Miscellaneous Processes: This category contains stationary source emissions which 

cannot be classified into those source groups already described. Included is the 

organic portion of both commercial and residential pesticide emissions. These sources 

combined are responsible for approximately 32 % of the ROG in the summer planning 

emissions inventory.

On-Road Motor Vehicles: This category is divided into vehicle types ranging from 

motorcycles to heavy duty trucks. Motor vehicle emissions occur both from combustion 

of fuel in the engine and from evaporation of fuel in the gas tank. This category 

represents a major portion of the ROG and NOx emissions in Imperial County, 

contributing approximately 54% of the NOx and 24% of the ROG in the 2002 summer 

planning emissions inventory.

Off-Road Mobile Sources: Included here are moving sources of air pollution that do not 

use paved roads. Examples are trains, boats, aircraft, off-road recreational vehicles, 

farm vehicles, and construction equipment. Some sources such as motorcycles can 

travel both on and off the road, but only emissions resulting from the latter activity are in 

this section. Emissions from these source types represent approximately 34% of the 

NOx and 17% of the ROG in the summer planning emissions inventory.
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One aspect of the summer planning inventory that is not readily apparent is that it does 

not include emissions from natural sources such as wildfires and biogenic emissions 

(organic compounds emitted from trees and plants) that are beyond the Air District’s 

control.

It is important to note that emissions for some source categories can vary from one 

ozone season to the next, while other sources may generate emissions at a relatively 

stable rate over an extended period. However, because the number of facilities that 

produce significantly variable emissions is low, there is not enough of an impact by 

these emissions to cause significant variances in the inventory. Considered as a whole, 

the effect of these fluctuations by individual facilities or source groups is largely muted 

by the substantial number and diversity of sources and by the volume of emissions 

generated each year. Because the 2002 emissions inventory is representative of the 

average emissions that occur during the summer planning period the use of the 2002

emissions inventory as the baseline emissions year is therefore appropriate for planning 

purposes.

Table 4-1

Emissions By Major Source Category 2002 Base Year

Summer Planning Emissions Inventory (tons/day)

Source Category ROG % 

Total NOx % Total

Stationary Sources

Fuel Combustion 0.12 0.32 3.57 9.54

Waste Disposal 0.02 0.05 0.00 0.00

Cleaning and Surface Coatings 0.42 1.13 0.00 0.00

Petroleum Prod. and Marketing 0.65 1.74 0.00 0.00

Industrial Processes 0.07 0.19 0.03 0.08

Total Stationary Sources 1.28 3.43 3.60 9.62

Area-wide Sources

Solvent Evaporation 9.01 24.14 0.00 0.00

Miscellaneous Processes 11.81 31.65 0.92 2.46

Total Area-Wide Sources 20.82 55.79 0.92 2.46

Mobile Sources

On-Road Vehicles 8.77 23.50 20.21 53.99

Off-Road Vehicles 6.45 17.28 12.70 33.93

Total Mobile Sources 15.22 40.78 32.91 87.92

Total for Imperial 37.32 100.00 37.43 100.00
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CHAPTER 4 – EMISSION INVENTORY Page 27 of 63

The 2002 summer planning emissions inventory is graphically displayed in Figures 4-1 

and 4-2.

Stationary Sources

3.4%

Area Wide Sources

55.8%

On-Road Vehicles

23.5%

Off-Road Vehicles

17.3%

Figure 4-1 Emissions By Major Source Category: 2002 Base Year 

- Reactive Organic Gases 

Stationary Sources

9.6%

Area-Wide Sources

2.5%

On-Road Vehicles

54.0%

Off-Road Vehicles

33.9%

Figure 4-2 Emissions By Major Source Category: 2002 Base 

Year - Nitrogen Oxides
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CHAPTER 5 – CONTROL MEASURES Page 28 of 63

CHAPTER 5 

CONTROL MEASURES

5.1 INTRODUCTION

5.2 CONTROL MEASURE ANALYSIS

5.3 STATIONARY SOURCE CONTROL MEASURES

5.4 TRANSPORTATION CONTROL MEASURES

5.5 INCENTIVE PROGRAMS

5.6 STATE STRATEGY
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CHAPTER 5 – CONTROL MEASURES

5.1 INTRODUCTION

The ICAPCD has the primary responsibility, under legislative authority, for regulating 

emissions from stationary sources as well as from some area sources found within the 

county. Currently, state and federal regulation prohibit the implementation of mobile 

source regulation by local air districts. 

At the state level, the CARB is responsible for regulating on-road motor vehicles, some 

off-road mobile sources, consumer products as well as setting motor vehicle fuel 

specifications in California. At the federal level, the U.S. EPA traditionally regulates 

emission sources related to interstate commerce such as locomotives, aircraft, heavyduty trucks and some off-road engines which are either exempt from state authority or 

are best regulated at the national level. Both the local and the combined state and 

federal component, together address the majority of the sources impacting air quality in 

Imperial County.3The ICAPCD recognizes that any maintenance of the NAAQS will 

depend largely on the current and proposed mobile source strategies under the state 

and federal jurisdictions.

The intent of this chapter is to provide the reader with an explanation of the existing

control measures which are an integral part of the Modified AQMP. Essentially, the 

control measures are a compilation of regulations which address how the Imperial 

County currently controls the emissions of Reactive Organic Gas compounds (ROG’s) 

and Nitrogen Oxides (NOx) within the moderate non-attainment area. Because mobile 

sources are a major contributor of ozone precursors this chapter dedicates a section to 

the regulations as adopted by the CARB. This chapter endeavors’ to provide the reader 

with an analysis of the currently existing control measures and endeavors’ to 

demonstrate how these control measures control ROG and NOx emissions as required 

by the CAA. Included in the discussion is a recap and assessment of the State strategy 

as a vital component of the Modified AQMP. Since, the late 1970’s and early 1980’s the 

ICAPCD has been committed to bringing major and non-major stationary sources under 

regulation for the effective control of precursor emissions.

5.2 CONTROL MEASURE ANALYSIS

The Modified AQMP control measures consist of three components: 1) the ICAPCD’s

Stationary Source Control Measures; 2) Regional Transportation Control Measures; and 

3) the State Strategy. These measures primarily rely on the traditional command and 

control approach and as such provide the framework for ICAPCD rules that reduce 

ROG and NOx emissions.

 

3

Although the Imperial County is currently in attainment of the 1997 8-hour ozone NAAQS, it is important to note 

that any future analysis of air emissions impacting Imperial County must take into consideration the influence of 

transport from three distinct sources, that of the South Coast Air Quality Management District (SCAQMD) via the 

Coachella Valley to the north, the San Diego Air Pollution Control District to the west and the international city of 

Mexicali, Mexico to the south.
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CHAPTER 5 – CONTROL MEASURES Page 30 of 63

5.3 STATIONARY SOURCE CONTROL MEASURES

This section provides a general overview of the current control measures as they apply 

to Imperial County. Currently adopted measures are represented as part of the most 

recently adopted rule book and represent ROG and NOx control measures adopted as 

part of the commitments contained in the previously approved 1991 Air Quality 

Attainment Plan (AQAP). The control measures discussed herein contain either or both 

Reasonably Available Control Measures (RACM) and/or Reasonably Available Control 

Technology. Although demonstrating the implementation of RACM is not a requirement 

for this Modified AQMP the ICAPCD finds it beneficial to explain how RACM is obtained 

through the adoption of RACT. RACM are non-technological measures which have 

been defined as cost-effective at reducing emissions. RACT are measures established 

by the U.S. EPA which have been scientifically proven techniques and/or equipment 

add-ons that can be applied to certain stationary sources to reduce ozone precursor 

emissions of ROG and NOx. These RACT measures are found within Control 

Technique Guidance (CTG) documents published by the U.S. EPA. As a result, the 

control measures adopted and implemented in Imperial County represent the 

implementation of all feasible control measures through the application of available 

technologies and management practices, as well as development and implementation 

of advanced technologies and control measures. Specifically, stationary source control 

measures are equipment and techniques for reducing air pollutant emissions from 

stationary sources. The stationary source control measures presented in the Modified 

AQMP are those measures representing emissions from both point sources (permitted 

facilities) and area sources (generally small and non-permitted) and have been found 

sufficient in maintaining the 1997 8-hour ozone NAAQS.

5.3.1 Control Measures with Emission Reductions Beyond 2002

The CAA requires that emission inventories be adjusted to reflect rule effectiveness. 

The baseline and future emission inventories have been adjusted to reflect applicability 

of the control measures described below. Table 5-1 below demonstrates the most 

current stationary source control measures which were evaluated and subsequently 

found to be sufficient in maintaining attainment of the 1997 8-hour ozone NAAQS. 

Table 5-1 also represents the modifications to the summer planning inventory as a 

result of the implementation of these measures. The ICAPCD is committed to continued 

implementation of these control measures.
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CHAPTER 5 – CONTROL MEASURES Page 31 of 63

Table 5-1

STATIONARY SOURCE CONTROL MEASURES

Emission Effective Emissions

Inventory Code TITLE Year Reductions

(EIC) Implemented (tpd)

520 – Architectural 

Coatings

ICAPCD Rule 424, 

Architectural Coatings, 

Updated on 02/23/2010

2010 0.49 tpd of 

ROG

620-618-0262-0101, 

Farming Operations, 

Dairy Cattle

ICAPCD Rule 217, Large 

Confined Animal Facilities 

Permits Required, Adopted 

on 10/10/2006

2007-2009 5.2 tpd of 

ROG

620-618-0262-0101, 

Farming Operations, 

Range Cattle

ICAPCD Rule 217, Large 

Confined Animal Facilities 

Permits Required, Adopted 

on 10/10/2006

2007-2009 0.04 tpd of 

ROG

620-618-0262-0101, 

Farming Operations, 

Feedlot Cattle

ICAPCD Rule 217, Large 

Confined Animal Facilities 

Permits Required, Adopted 

on 10/10/2006

2007-2009 1.6 tpd of 

ROG

ICAPCD Rule 400.1, 

Stationary Gas Turbines 

(RACT)

2010 No Impact

ICAPCD Rule 400.2, Boilers, 

Process Heaters and Steam 

Generators (RACT)

2010 0.39 tpd of 

NOx

C- 424 Architectural Coatings (Amendment)

Architectural coatings are products that are applied to stationary structures and their 

accessories. They include house paints, stains, industrial maintenance coatings, traffic 

coatings, and many other products. Architectural coatings represent a significant 

source of VOC emissions throughout California. When these coatings are applied, 

VOCs are emitted from the coatings and from solvents that are used for thinning and 

clean-up. The ICAPCD updated its Architectural Coatings Rule according to the 2007 

Suggested Control Measures (SCM) developed by CARB. The new revisions to the 

Architectural Coatings Rule are to enhance the effectiveness of the SCM in obtaining 

ROG emission reductions. 

The baseline for determining emission reductions is the 2004 data from CARB’s survey. 

For architectural coatings, the 95 tpd of statewide VOC emissions are apportioned to 

ICAPCD’s based on population. The SCM is intended for districts outside of the South 

Coast AQMD. In addition, emission reductions are only calculated for large containers, 

because small containers (one liter or less) are exempt from the proposed VOC limits.
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CHAPTER 5 – CONTROL MEASURES Page 32 of 63

Amendment Adoption: 2010

Applicable ICAPCD Rule: 424 

Cost-Effectiveness: Individual limits range from a net savings to a net cost of $ 13.90 

per pound of VOC reduced. However, the overall average cost-effectiveness of the 

proposed limits is estimated to be $1.12 per pound of VOC reduced.

Year 2010 ROG Emission Reduction: 0.49 tpd

C-217 Large Confined Animal Facilities Permits Required

In accordance with Senate Bill 700 (SB700) – Florez – Agricultural Sources, on 

November 10, 2006, the ICAPCD adopted Rule 217 – Large Confined Animal Facilities 

(LCAF) Permits Required. Rule 217 requires that all LCAFs, including beef feedlots and 

dairies, apply for and obtain an Authority to Construct/Permit to Operate which includes 

a mitigation plan for which the LCAF implements in order to reduce VOC emissions. 

Any permit that is issued to a LCAF is subject to all pertinent provisions of the California 

Health & Safety Code and the ICAPCD Rules and Regulations. Rule 217 is currently 

being implemented and targets reductions of VOC and NH3 emissions. Rule 217 

requires compliance with RACT by providing a menu of mitigation measures for beef 

feedlots and dairies which comply with RACT measures.

Adoption: 2006

Applicable ICAPCD Rule: 217

Cost-Effectiveness: For dairies (3 in Imperial County) the cost effectiveness is $17,800 

per ton of VOC reduced while Beef Feedlots (approximately 26) have a cost 

effectiveness of $14.00 per ton of VOC reduced.

Year 2010 ROG Emission Reduction: 6.84 tons per day

C- 400.1 Stationary Gas Turbines

Rule 400.1 was adopted to address RACT requirements. Essentially, Rule 400.1 

imposes RACT upon any unit with a rated heat input capacity of 1 Megawatt (MW) or 

more. The rule establishes NOx limits of 42 parts per million by volume (ppmv) for 

gaseous fuel-fired units and 65 ppmv liquid fuel-fired units. The rule does not require the 

use of emission control technologies which might degrade or endanger the environment 

upon existing units. Rule 400.1 affects seven stationary gas turbines at four Imperial 

County major source facilities. These facilities already substantially comply with the 

specified thresholds imposed upon by this rule, so no significant changes in current 

Authority to Construct or Permit to Operate conditions are anticipated. Since, all existing 

emission units affected by Rule 400.1 are able to comply without additional installation of 

technology a substantial change, resulting from the implementation of this rule, in the 

emissions inventory for these facilities is not anticipated. The staff report contains a more 

detailed analysis on the impact and cost effectiveness associated with the implementation 

of the rule.

Adoption: February 23, 2010

Applicable ICAPCD Rule: 400.1
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Cost-Effectiveness: Four major source facilities were affected in Imperial County by the 

adoption of this rule. The cost-effectiveness for the natural gas unit is $61,731 per ton 

of NOx and for the diesel units the cost effectiveness is $44,839 per ton of NOx

Year 2010 NOx Emission Reduction: No Impact

C- 400.2 Boilers, Process Heaters and Steam Generators

Like Rule 400.1, Rule 400.2 was adopted to address RACT requirements. Essentially, 

Rule 400.2 applies RACT to any unit with a rated heat input capacity of 5 million British 

thermal units per hour (MMBtu/hr) or more. The rule imposed a NOx limit of 30 ppmv 

(0.036 lb/MMBtu) for gaseous fuel-fired units and 40 ppmv (0.052 lb/MMBtu) for liquid 

fuel-fired units. The 30 ppmv gaseous-fuel limit is generally achievable via combustion 

controls such as low-NOx burners, oxygen control, staged combustion, and flue gas 

recirculation. The 40 ppmv non-gaseous fuel limit is achievable using combustion 

controls and low nitrogen content "clean" fuels, or by using post-combustion controls. In 

addition, Rule 400.2 established an alternative NOx emission limit of 70 ppmv for those 

emission units with an annual capacity factor of 30% or less. This alternative emission 

threshold was established for those peaking or seasonal emission units for which 

installation of advanced control technology would not have a significant impact in 

reducing NOx emissions. The rule similarly contains an alternative NOx threshold for 

biomass boilers equivalent to 120 ppmv at 12% CO2 or as an alternative biomass boilers 

will be required to reduce NOx emissions at a minimum of 89% of the uncontrolled NOx 

emission concentration in the exhaust gas stream. Rule 400.2 affects several industries 

and businesses in Imperial County including some of our major source facilities. 

Adoption: February 23, 2010

Applicable ICAPCD Rule: 400.1

Cost-Effectiveness: The cost-effectiveness ranged between the models for each 

impacted boiler. However on the average for a 50 MMBtu/hr, 100 MMBtu/hr, 150 

MMBtu/hr and a 200 MMBtu/hr the cost-effectiveness is approximately $74,700, 

$108,300, $124,900 and $148,200 respectively.

Year 2010 NOx Emission Reduction: Approximately 143.3 tpy

5.3.2 External Adjustments to the Emissions Inventory

The “external adjustments” listed in Table 5-2 describe the recent adjustments 

accounted for external modifications to the CARB CEFS v1.06 Summer Planning 

Inventory. The adjustments incorporate the most recent data changes to the emissions 

inventory identified by CARB specific to Imperial County. The Modified AQMP

emissions inventory was modified to incorporate changes that occurred between 2002 

and 2009.
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Table 5-2

CARB ADJUSTMENTS TO THE EMISSIONS INVENTORY BASELINE

Emission Effective Emissions

Inventory Code Description Year Reductions

(EIC) Implemented (tpd)

050-995-0110-0000, Fuel 

Combustion, 

Manufacturing and 

Industrial, Other, Natural 

Gas

NOx summer emissions 

were reduced based on 

updated natural gas data 

from the CA Energy 

Commission.

2002-2009 4.7 tpd of 

NOx in 2002 

and 5.2 tpd 

NOx in 2009

060-995-0110-0000, Fuel 

Combustion, Services 

and Commercial, Other, 

Natural Gas 

NOx summer emissions 

were reduced based on 

updated natural gas data 

from the CA Energy 

Commission.

2002-2009 0.3 tpd of 

NOx in 2002 

and 2009

530, Pesticides/Fertilizers ROG emissions were 

reduced based on 2004 

pesticide emissions 

inventory data provided 

by the Department of 

Pesticide Regulation.

2002-2009 0.14 tpd 

ROG in 2002 

and

0.33 tpd 

ROG in 2009

5.3.3 Reasonably Available Control Measures

Stationary source control measures rely on a variety of control technologies and 

management practices and as such the ICAPCD is seeking all feasible control 

measures that will aid in maintaining compliance with the federal and state standards. 

CAA sections 172(c)(1) and (c)(2) requires ozone non-attainment areas to submit a plan 

which contains provisions for the implementation of all RACM as expeditiously as

practicable. Although, RACM is not required for this Modified AQMP it is beneficial to 

explain that RACM applies to stationary source control measures and transportation 

control measures and that the ICAPCD has nonetheless met the RACM requirements 

for stationary sources as demonstrated through the 2009 RACT SIP Report, 

summarized below.

Reasonably Available Control Technology

Ozone non-attainment areas are required by sections 182(b)(2) and 182(f) of the CAA 

to implement RACT for sources which are subject to CTG documents and for those

major sources of ROG and NOx. RACT is defined as the lowest emissions limitation 

that a particular source is capable of meeting by the application of control technology 

that is reasonably available considering technological and economic feasibility (44 FR 

53762; September 17, 1979). In essence RACT requirements, as specified in the CAA, 

assure that major sources of ozone precursor emissions are controlled to a 

“reasonable” extent, but not necessarily to the more stringent best available control 

technology (BACT) or maximum achievable control technology (MACT) levels, expected 
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for new or modified existing major stationary sources. CTGs are EPA documents that 

define RACT for existing sources of air pollution. 

Reasonably Available Control Technology (RACT) State Implementation Plan 

(SIP).

As part of the implementation process described in U.S. EPA’s Final Rule to Implement 

the 8-Hour ozone NAAQS (70 FR 71612; November 29, 2005) a RACT demonstration 

is required of all areas classified as a moderate or higher ozone non-attainment area. 

In order to accomplish the RACT demonstration ICAPCD staff reviewed the list of CTG 

documents and compared them to existing rules and existing stationary sources. For 

each source category ICAPCD staff identified existing sources and applicable rules. 

This was accomplished by reviewing and researching the permit system, the phone 

book, internet and the emissions inventory. The criteria used for the evaluation and 

determination of the RACT SIP rules were based on 1) U.S. EPA rule approval and 2) 

RACT/BARCT determinations issued by CARB. 3) Comparison to other Moderate nonattainment areas. All CTG sources and major non-CTG sources under ICAPCD 

jurisdiction are controlled to RACT or better. Based on its review, the ICAPCD made a 

determination that all ozone precursor rules fulfill RACT requirements for the 1997 8-

hour ozone NAAQS. In addition, with the adoption of Rules 400.1 and 400.2, the 

ICAPCD believes it not only fulfills VOC requirements but NOx requirements as well.

The ICAPCD intends to adopt its RACT SIP in conjunction with this Modified AQMP and 

send both documents to CARB for submittal to the U.S. EPA. 

5.3.4 New Source Review

New Source Review (NSR) is a permitting process required by the CAA to help ensure 

that any new or modified equipment and facilities (i.e. boilers, turbines, crude oil 

storage tanks, power plants and factories) do not significantly degrade air quality or 

slow progress towards clean air. The ICAPCD rule which dictates the NSR 

requirements is the NSR rule 207. There are two primary components of NSR, the 

application of BACT and emission offsets. BACT plays a very important role in helping 

the ICAPCD to meet the no net increase in emissions required by the CAA by acting 

as an emissions limitation on pollutants emitted from or resulting from any new or 

modified stationary source. Emissions reduction credits (ERC’s) are credits which are 

issued to sources that have reduced their emissions in excess of what is required by 

law. These emission reductions are banked and made available for offsetting 

emission growth from new or modified emissions units. 

BACT is currently required for all new or modified emission units which have a potential 

to emit of 25 pounds per day or more of any non-attainment pollutants. New or modified 

sources with potentials to emit of 137 pounds per day of NOx and ROG will be required 

to offset those emissions through the use of ERC’s. These reductions must be 

permanent, real, enforceable, quantifiable and surplus.
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There are two versions of NSR rule that are enforced by the ICAPCD. A current version 

adopted as an amendment by the ICAPCD Air Board on October 10, 2006 and a SIPapproved rule version of Rule 207, Standards for Permit to Construct, approved on 

November 10, 1980. Both versions of Rule 207 fulfill the requirements of CAA Sections 

172(c)(4) and (5), 182(a)(2)(C) and the 1.15 to 1 offset ratio required by Sections 

182(a)(4) and 182(b)(5).

5.4 TRANSPORTATION CONTROL MEASURES

The largest source of ROG and NOx emissions for the summer planning inventory are 

by far mobile sources, which emit approximately 47% of the total ROG and 86% of the 

total NOx in 2009. Reduction of ozone precursor emissions from mobile sources is 

twofold: the first discussion is region wide while the second is local. The measures

implemented region wide are consistent with the Regional Transportation Plan (RTP) 

adopted by the South California Association of Governments (SCAG). The 

transportation mitigation programs contained in SCAG’s RTP were adopted to help 

maintain reductions of ROG and NOx emissions on a regional basis. 

For the local strategy, the ICAPCD relied on the reductions of vehicle miles traveled 

(VMT) associated with the implementation of the Imperial County CEQA Air Quality 

Handbook (CEQA handbook). The CEQA handbook utilizes mitigation measures, 

imposed upon commercial, residential and industrial projects which help to reduce 

ROG, NOx, and particulate matter from mobile source emissions created by the 

operational phase of the residential, commercial and industrial projects.

5.4.1 Regional Measures

SCAG functions as the Metropolitan Planning Organization (MPO) for six counties, Los 

Angeles, Orange, San Bernardino, Riverside, Ventura and Imperial. As the designated 

MPO, SCAG is mandated by the federal government to research and plan for 

transportation, growth management, hazardous waste management and air quality. 

The byproduct of this research is the 2008 RTP.

The 2008 RTP is SCAG’s multi-modal plan for a better regional transportation system, 

integrated with the best possible growth pattern for the region out to 2035. The plan 

provides the basic policy and program framework for long-term investment in the 

region’s vast transportation system in a coordinated, cooperative and continuous 

manner. Transportation investments in the SCAG region that receive state or federal 

transportation funds must be consistent with the RTP and must be included in the RTP 

when ready for funding. 

As part of its many functions SCAG is required by law to ensure that transportation 

activities “conform” to and are supportive of, the regional and state air quality plans to 

attain the NAAQS. That is, SCAG has the responsibility under the CAA to determine 

conformity by comparing the Air Plan against projects, plans and programs, including 

the Transportation Conformity Rule. As such, SCAG’s 2008 RTP provides the basis for 
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the transportation control measures for the Modified AQMP.

Currently, long term transportation planning requirements which target emission 

reductions from on road mobile sources, within the basin, are met by SCAG’s RTP 

which is developed every four years with a 30 year planning horizon. The short term 

implementation requirements of the Transportation Conformity Rule are met by SCAG’s 

biennial Regional Transportation Improvement Plan (RTIP). 

Measures which reduce motor vehicle emissions by intentionally causing the reduction 

of vehicle trips, vehicle use, VMT, vehicle idling and traffic congestion are known as 

Transportation Control Measures (TCM’s). The 2008 RTP includes the following types 

of transportation mitigation programs:

Increased rideshare and work-at-home opportunities to reduce demand on the 

transportation system.

Investments in non-motorized transportation and maximizing the benefits of the 

land use-transportation connection.

Travel Demand Management (TDM) measures.

Goods movement capacity enhancements.

Key transportation investments targeted to reduce heavy-duty truck delay.

With each new RTP update a new list of TCMs from the first two years are rolled over 

into the Modified AQMP upon approval by CARB and U.S. EPA. Once a TCM project is 

completed, it is reported in the RTP update as completed and removed from future 

RTPs. However, a TCM substitution is required when a committed TCM project cannot 

be delivered or will be significantly delayed. Here, in Imperial County the Imperial 

County Transportation Commission (ICTC), in consultation with SCAG, is the agency 

which reviews projects to determine if TCMs are defined by a project according to the 

categories as listed below. Table 5-3 represents the TCM projects which have been 

deemed feasible in Imperial County. The TCM’s listed are project categories for which 

local cities and the Imperial County have either implemented or are proposing as future 

measures.
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Table 5-3

REGIONAL TRANSPORTATION PLAN

TRANSPORTATION CONTROL MEASURE PROJECT CATEGORIES

Project Category

A Ridesharing Measures

Carpooling, Vanpooling, Park and Ride Lots, Ride Matching Services, Incentive 

Programs, Satellite Work Centers, Guaranteed Ride Home Programs, Station 

Cars, Onsite Services

B Non-Motorized Measures

Bicycle Paths/Facilities, Pedestrian Paths/Facilities, Telecommuting, Flexible 

Work Schedules, Bicycle and Pedestrian Programs

C Traffic Flow Improvement Measures

Signal Synchronization, Intersection Improvements, Incentive/Disincentive 

Programs, High Occupancy Vehicle Lanes, Intelligent Transportation Systems,

Ramp Metering

D Land Use Measures

Transportation Demand Management (TDM) Ordinances, Smart 

Growth/Sustainable Community Projects, Mixed Use Development, Parking 

Management and Standards, Congestion Management Plan, TDM Strategies

E Transit Measures

Bus Fleet Expansion, Shuttles and Paratransit Vehicles Expansion, Transit 

Stations and Facilities, Express Busways, Passenger Rail Service, Rail Stations 

and Facilities, Real-Time Transit Information Systems, Transit Subsidies.

5.4.2 Local Strategy

On November 6, 2007, the Imperial County Air Pollution Control District Board of 

Directors approved the ICAPCD’s guidance document known as the CEQA Air Quality 

Handbook. The CEQA handbook provides guidance to all interested parties on the 

significance of impacts resulting from the development of new residential, commercial, 

and industrial projects. Once the significance of the impact is determined, the CEQA 

handbook provides a list of feasible mitigation measures which are implemented for the 

reduction of those direct and indirect emissions created by the development project. 

Specifically, the CEQA handbook requires mitigation of construction and operational air 

emissions. However, important to the Modified AQMP is the reduction of mobile source 

emissions created as an indirect source of a development project. That is, the great 

majority of emissions during the operational phase of a project are from mobile source 

emissions in the form of increased VMT. The CEQA handbook serves as a guidance to 

help reduce or eliminate the number of VMT associated with new development projects. 

Therefore, the ICAPCD has adopted the CEQA measures as TCM’s for the local 

strategy in reducing or eliminating VMT’s. 

Table 5-4 presents a list of the local TCM’s which will either reduce or eliminate the 

number of VMTs. 
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Table 5-4

IMPERIAL COUNTY CEQA AIR QUALITY HANDBOOK

TRANSPORTATION CONTROL MEASURES

Local TCMs for Residential 

Projects

Local TCMs for Commercial 

Projects

Standard Site Design Measures

Link cul-de sacs and dead-end streets to 

encourage pedestrian and bicycle travel;

Provide on-site bicycle lockers and/or 

racks;

Allocate easements or land dedications for 

bikeways and pedestrian walkways;

Provide on-site eating, refrigeration and 

food vending facilities to reduce lunchtime 

trips;

Provide continuous sidewalks separated 

from the roadway and adequate lighting;

Provide shower and locker facilities to 

encourage employees to bike and/or walk 

to work;

Provide bicycle storage at apartment 

complex or condos without garages;

Discretionary Site Design Measures

If project near transit route, improve 

accessibility;

If project near transit route, improve 

accessibility;

Increase street tree planting; Increase street tree planting;

Outdoor electrical outlets to encourage 

use of electric appliances and tools;

Improve on-site circulation design 

elements in parking lots to reduce vehicles 

queuing;

Provide bikeways lanes and/or link new 

bikeways lanes to existing;

Increase the number of bicycle 

routes/lanes;

Increase the number of bicycle 

routes/lanes;

Provide pedestrian signalization to 

improve pedestrian safety;

Provide pedestrian signalization to 

improve pedestrian safety;

Synchronize traffic lights on street 

impacted by development;

Synchronize traffic lights on street 

impacted by development;

Use Energy Efficiency Design Measures. Use Energy Efficiency Design Measures.

Standard Site Design Measures for Industrial Projects

Implement carpool/vanpool programs and incentives (i.e. carpool ride matching for 

employees, assistance with vanpool formation, provision of vanpool vehicles, etc.)

Provide for shuttle/mini bus service such as to establish a shuttle service from 

residential care areas to the worksite.

Provide preferential carpool and vanpool parking

Construct transit facilities such as bus turnouts/bus bulbs, benches, shelters, etc if the 

project is located on an established transit route.

Design and locate buildings to facilitate transit access (i.e., locate building entrances 

near transit stops, eliminate building setbacks, etc.)

Provide incentives to employees to take public transportation, walk, bike, etc.

Provide pedestrian signalization and signage to improve pedestrian safety.

Implement on-site circulation design elements in parking lots to reduce vehicle queing 
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Table 5-4

IMPERIAL COUNTY CEQA AIR QUALITY HANDBOOK

TRANSPORTATION CONTROL MEASURES

and improve the pedestrian environment.

Provide on-site bicycle and motorcycle parking. Such as providing weather-protected 

bicycle parking for employees.

Provide safe, direct access for bicyclists to adjacent bicycle routes.

Provide shower and locker facilities to encourage employees to bike and/or walk to work 

– typically, one shower and three lockers for every 25 employees.

Provide on-site eating, refrigeration and food vending facilities to reduce lunchtime trips.

Increase street tree planting

Measures which meet mandatory, prescriptive and/or performance measures as 

required by Title 24.

Use low emission fleet vehicles such as TLEV, ULEV, LEV, ZEV

Install an electrical vehicle charging station with both conductive and inductive charging 

capabilities.

Use built-in energy efficient appliances, where applicable.

5.5 INCENTIVE PROGRAMS

5.5.1 Carl Moyer Program

The majority of the new measures in the California state strategy encompass in-use 

measures which have traditionally resulted in flexible regulation – allowing the most 

cost-effective method to be used by those having to meet the emission requirements. 

Therefore, to accomplish early retirement of older more polluting engines the use of 

funding programs, such as Carl Moyer, became an integral part of creating emission 

reductions for Imperial County. 

The Carl Moyer program essentially encourages the early introduction of clean air 

technologies onto the on-road and off-road vehicle fleets by providing funds to help 

purchase new vehicles or new engines (repowers) and for the installation of retrofit units 

on older engines. A variety of vehicle classes and types are funded under the Carl 

Moyer Program to help purchase new vehicles or new engines/repowers and for 

installation of retrofit units on older engines. In particular, this funding provides the 

technologies that reduce NOx and PM emissions caused by the combustion of diesel 

powered engines. Essentially, both new and retrofit engines should be CARB-certified 

and CARB-verified. The guidelines adopted for the Carl Moyer Program include “Fleet 

Modernization” and “Light-Duty Vehicle repair and Scrapping” programs. Although all 

potential projects must meet cost-effectiveness requirements to be eligible for funding 

considerations, less polluting engines, such as alternative fuel engines will be given 

preference for funding. New vehicles and engines must achieve a 30 percent reduction 

and repowered vehicles and retrofits must achieve a 15 percent reduction of NOx 

emissions compared to current emission standards. Therefore the move to cleaner 

burning engines holds a potential for the ICAPCD to take credit for the emission 

reductions achieved through past and future projects funded under this program. For 
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CHAPTER 5 – CONTROL MEASURES Page 41 of 63

example, in 2007 estimated reductions as a result of the Carl Moyer Program for all 

applicable subcategories is reflected in the Table 5.5 below. 

Table 5-5

CARL MOYER PROGRAM 

REDUCTIONS IN TONS PER YEAR 

(tpy) FOR 2007

TOTAL EMISSION REDUCTIONS

NOx ROG PM

Grand Total 12.710 1.579 0.445

5.5.2 Emission Reductions from New Residential and Commercial 

Development Projects

The California Environmental Quality Act (CEQA) requires the identification of 

significant environmental impacts resulting from proposed projects and the reduction of 

those emissions by the application of feasible mitigation measures. Specifically, new 

development projects produce new sources of air pollution from new vehicle trips, use 

of consumer products, landscape maintenance, and fuel combustion. New residential, 

commercial, and industrial projects are required to implement standard and 

discretionary design measures to reduce air quality impacts. Since emissions from 

development projects cannot be entirely mitigated on-site, the ICAPCD adopted Rule 

310, Operational Development Schedule Fee, which mandates development projects to 

mitigate emissions in off-site projects or to pay a mitigation fee that would be used to 

fund projects that reduce emissions in the most cost-effective manner possible.

Typically, off-site reductions can occur as a result from either stationary or mobile 

sources. For example, NOx emissions from increased vehicle trips from a residential 

development could be reduced by funding the expansion of existing transit services.

5.5.3 Mobile Source Emission Reduction Credit Banking

The ICAPCD adopted in October 2006 Rule 214.1 Mobile Source Emission Reduction 

Credit (MSERC) Banking which was modeled after the Voluntary Accelerated Vehicle 

Retirement (VAVR) Program developed by CARB. This rule provides an incentive for 

the early removal of older more polluting vehicles. The potential level of emission 

reductions available through the use of an early retirement program will depend on the 

number of available older vehicles registered in Imperial County, the price a credit 

seeker is willing to pay, and the number of owners that are willing to sell their vehicles at 

the price offered. 

5.6 STATE STRATEGY

On September 27, 2007, CARB adopted the state Strategy for California’s 2007 SIP to 

achieve the additional emission reductions needed for all areas of the state, including 
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CHAPTER 5 – CONTROL MEASURES Page 42 of 63

Imperial County, to attain both the federal 1997 8-hour ozone and the PM2.5 standards.4

The SIP outlines the plan for meeting air quality standards in all of its non-attainment 

areas. The State Strategy, including the control measures, revisions, and appendices, is 

available on CARB’s SIP website. The control measures in CARB’s State Strategy 

target passenger vehicles, trucks, construction equipment, agricultural equipment, 

goods movement, fuels, recreational vehicles and boats, and pesticides. Both CARB 

and U.S. EPA, who have primary regulatory authority over mobile sources, implement 

the measures within the State Strategy. Without regulatory authority the ICAPCD is 

unable to implement any of the measures found within the SIP State Strategy. 

However, the Modified AQMP incorporates the measures by reference and as such 

reflects those NOx and ROG emission reductions that the measures achieve in Imperial 

County.

 

4

The CARB adopted a revision to the state strategy on April 24, 2009. The proposed revision accounts for emission 

reductions from the regulations adopted in 2007 and 2008, clarifies ARB’s legal commitments in light of U.S. EPA’s 

approval criteria, and clarifies the discussion of the long-term strategy for identifying future technologies to achieve 

the last increment of reductions. The proposed revision does not change the emission reductions of oxides of 

nitrogen, reactive organic gases, oxides of sulfur and direct PM2.5 that the Board committed to achieve by specific 

years when it adopted the 2007 State Strategy.
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CHAPTER 6 – EMISSION FORECAST Page 43 of 63

CHAPTER 6

EMISSION FORECAST

6.1 INTRODUCTION

6.2 FORECAST METHODS AND ASSUMPTIONS

6.3 EXTERNAL ADJUSTMENTS TO EMISSION INVENTORY 

6.4 EMISSION INVENTORY FORECAST

6.5 EMISSION INVENTORY TRENDS

6.6 TRANSPORTATION CONFORMITY
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CHAPTER 6 – EMISSION FORECAST Page 44 of 63

CHAPTER 6 - EMISSION FORECASTS

6.1 INTRODUCTION

Any evaluation of control measure effectiveness must include future emissions impacts. 

These impacts are typically analyzed in order to ascertain whether the control measures 

as implemented will be enough to maintain the 1997 8-hour ozone NAAQS or whether

new control measures will be required. The primary tool utilized to analyze future 

impacts is the emissions forecast. The emission forecast provides estimates of future 

year emissions by projecting the effects of economic growth and existing regulations on 

future year emission inventories. The resulting projections can be used for a variety of 

purposes, including modeling of future air quality, assessing the effectiveness of new 

and proposed control measures, analyzing new source impacts, and tracking progress 

towards clean air.

The 2002 emissions inventory presented in Chapter 4 provides an up-to-date, 

comprehensive base inventory that can be used to forecast future year emissions. 

Since this Modified AQMP only addresses ozone, only emissions forecast of ROG and 

NOx, the precursors to ozone, are presented. Therefore, the 2002 planning inventory 

was used to generate emissions forecast for the years 2005 on thru 2023.

Essentially, the forecast inventories shown in this chapter take into account projected 

socioeconomic growth and the emission reductions ICAPCD rules as adopted are 

expected to generate. Emission reductions from control measures adopted prior to 

2009 by the state CARB, for consumer products, pesticides, mobile sources, and mobile 

source controls adopted by U.S. EPA, are also reflected in the baseline future 

emissions forecast.

6.2 FORECAST METHODS AND ASSUMPTIONS

Emissions forecast are generated by applying emission growth and control estimates to 

the baseline emissions inventory. The California Emissions Forecasting System 

(CEFS), a computer model maintained by CARB, stores the baseline inventory, growth, 

and control data, and uses pollutant-specific algorithms to generate the inventories used 

in this Plan. This section describes the general methodology used to estimate 

emissions in future years. 

The formula CEFS uses to forecast future year baseline emissions is as follows:

FYt = BY*GFt*CFt

Where:

FYt = controlled planning day emissions for the forecast year (t)

BY = base year (2002) planning day emissions per process

GFt = growth factor for forecast year (t)

CFt = control factor for forecast year (t)
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CHAPTER 6 – EMISSION FORECAST Page 45 of 63

Growth Factors 

The emissions inventory is made up of individual source categories (base year emission 

category), each with its own socioeconomic activity factor and emissions factor as 

described in Chapter 4. To account for future growth, each of the base year emission 

categories is assigned a related activity indicator, such as population, housing, 

employment, or economic activity. These activity indicators are specific to each

industry, for which future estimates are to be developed.

For most emission categories, general socioeconomic trends such as projected 

population or economic growth are the driving force behind the growth assumptions 

used in the emissions forecast. Some categories, however, such as on-road motor 

vehicles, electric utilities and others, may use more specific trend assumptions. For 

example, vehicle emissions were projected using changes in activity levels related to 

Vehicle Miles Travelled (VMT), Vehicle turnover, emission controls, fuel characteristics 

and consumer purchase patterns. VMT’s, are typically provided by SCAG while CARB's 

EMFAC2007 model provides all other factors needed for the vehicle emissions 

projection. Growth factors for the energy categories are derived from the California 

Energy Commission’s (CEC) energy use forecast.

Emission Controls

In addition to changes in socioeconomic conditions and specific trend assumptions, 

emissions will change over time due to the implementation process of a control 

measure known as a control factor. 

A control factor is a combination of the following four elements:

1. technological control efficiency (CE) of the control technology, equipment or 

strategy requirement of the control measure;

2. compliance efficiency, or rule effectiveness (RE) of the control measure, 

reflecting the actual “real world” ability of a control measure to achieve expected 

emission reductions;

3. Rule penetration (RP), or impact factor, representing the relative amount of 

emissions in a source category subject to a control measure, Taking into 

consideration any exemptions and other control measures; and,

4. implementation factors (IP), or relative amount of total control taking place in a 

given year, for control measures having phased implementation or control 

requirements taking place in tiers.

Control factors are useful in that they are used to quantify the remaining uncontrolled 

emissions in a source category after controls are applied in order to understand the 

impact to the emissions inventory. This impact or lack of impact to the emissions 

inventory helps the ICAPCD make appropriate determinations concerning rule 

development. Control Factors are represented by the following equation:
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CHAPTER 6 – EMISSION FORECAST Page 46 of 63

CF = 1 – (CE*RE*RP*IP)

Control Factors are specific to an emission source and are relative to the control levels 

for the base year 2002 which helps in the understanding of future year projected 

emission controls

Uncertainties in Forecasting

As with any forecasting scheme, the one used for the emission projections presented in 

this Modified AQMP can only be at best an estimate. Original forecasts in 2002 for 2010 

could not have taken into account the decline in the economic stability currently 

witnessed. With the decrease in employment opportunities and the closing of 

businesses across all sectors earlier emissions projections may be lower than 

previously estimated creating a lower emissions projection. 

Likewise, the Department of Finance’s (DOF) population estimates are primarily based 

on past growth trends and do not account for potential resource constraints or other 

limitations to growth. Thus, the projected future emissions for source categories that are 

population dependent may be overestimated if population does not increase at the 

forecasted rate.

Conversely, if an existing control is not as effective as is estimated in the emission 

inventory, then future emissions would be higher than the forecast for that source 

category. Also, unforeseen technological changes could alter the accuracy of the 

emissions forecast.

The baseline inventory used to develop this plan reflects our understanding of sources, 

activity levels, and emission rates at a singular point in time. Planners use this “frozen” 

inventory to provide a stable base for an analysis of the causes of air pollution in the 

Imperial County and to evaluate the impact of current and potential new controls. 

However, the development of the baseline and forecast inventories is a dynamic 

process. Our understanding of the elements that go into the inventory and forecasts -

the activity levels, emission rates, growth and control factors - changes as we learn 

more about each source category. Activity indicators (such as population, fuel 

consumption, etc.) must also be adjusted occasionally to reflect current socioeconomic 

conditions. Thus, refinement of the emission estimates is an ongoing process as new 

and better data becomes available. Future updates to the Modified AQMP will include 

revised estimates of both the baseline and forecast emissions.

6.3 EXTERNAL ADJUSTMENTS TO THE EMISSIONS INVENTORY

Table 6-1 identifies the primary updates made after CARB’s CEFS v1.06 baseline 

inventory was finalized. These “off-model” adjustments are reflected in the emission 

projections for the Modified AQMP. The emission changes shown are the tons per day 

(tpd) impact during the summer months. 
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CHAPTER 6 – EMISSION FORECAST Page 47 of 63

Table 6-1 

CARB ADJUSTMENTS TO THE EMISSIONS INVENTORY BASELINE

Emission Effective Emissions

Inventory Code Description Year Reductions

(EIC) Implemented (tpd)

050-995-0110-0000, Fuel 

Combustion, 

Manufacturing and 

Industrial, Other, Natural 

Gas

NOx summer emissions 

were reduced based on 

updated natural gas data 

from the CA Energy 

Commission.

2002-2009 4.7 tpd of 

NOx in 2002 

and 5.2 tpd 

NOx in 2009

060-995-0110-0000, Fuel 

Combustion, Services 

and Commercial, Other, 

Natural Gas 

NOx summer emissions 

were reduced based on 

updated natural gas data 

from the CA Energy 

Commission.

2002-2009 0.3 tpd of 

NOx in 2002 

and 2009

530, Pesticides/Fertilizers ROG emissions were 

based on 2004 pesticide 

emissions inventory data 

provided by the 

Department of Pesticide 

Regulation.

2002-2009 0.14 tpd 

ROG in 2002 

and

0.33 tpd 

ROG in 2009

6.4 EMISSION INVENTORY FORECAST

This section summarizes the ROG and NOx emissions inventory forecast for 2009. The 

2009 average annual and summer planning emissions inventories were developed from 

the 2002 Base Year Inventory, applying the CEFS growth factors and the impact of 

current control programs as described in Chapter 5. Resulting emission projections for 

2009 average annual and summer planning emissions inventories are summarized in 

Table 6-3 and Table 6-4, respectively. A detailed breakdown of emissions per each 

source category is presented in Appendix B.

Both ROG and NOx emissions are predicted to decrease dramatically in Imperial 

County from 2002 to 2009 due to existing State and ICAPCD control measures and 

programs, as discussed in Chapter 5. The emission reductions discussed in this 

section, and depicted in Table 6-3 result from the control strategies relied upon for 

compliance with existing CAA requirements. Newly adopted controls as well as existing 

controls as described in Chapter 5 provide additional emissions reductions and 

contribute towards the maintenance of the 1997 8-hour ozone NAAQS.

The emission inventory data depicted in this document was obtained from CEFS, 

Version 1.06, and CARB’s Planning and Support Division. The on-road mobile source 

data was evaluated by the Planning and Support Division using EMFAC2007 v2.3 and 

updated using the vehicle population information provided by SCAG as of March 2008.
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CHAPTER 6 – EMISSION FORECAST Page 48 of 63

Table 6-2 shows important motor vehicle growth indicators from the CARB EMFAC2007

v2.3 on-road mobile model and SCAG’s 2008 RTP.

Table 6-2

MOTOR VEHICLE GROWTH TRENDS

Imperial County 

Totals

Indicators 2002 2009

All vehicle categories Vehicles 121,707 161,231

Vehicle miles traveled 

(x1000)

VMT/1000 4,780 6,277

All vehicle trips Trips 808,700 1,054,090

Fuel Consumption (1000 

gallons)

Gasoline 217.44 285.15

Diesel 97.07 115.09

Notes: EMFAC2007v2.3; Nov 1, 2006 Run Date: 03/18/2008 Season Summer

The 2009 summer planning emissions inventory is summarized in Table 6-3. An 

examination of this table provides the following information.

1. Total emissions of ROG for Imperial County were calculated at 32 tpd for the 2009 

summer planning emissions inventory. Table 6-3 shows that over 21 % of daily ROG

emissions are attributable to on-road vehicles, primarily automobiles. Other mobile 

sources, such as off-road vehicles, trains, and aircraft contribute another 26 % of 

these emissions. Area sources such as: solvent use (emissions from pesticides 

application), petroleum related activities, and farming operations (emissions from 

feedlots and dairies) constitute most of the remaining ROG emissions with 

approximately 48%.

2. The total NOx emissions in summer 2009 were estimated to be 32 tpd. As shown in 

Table 6-3, sources in the on-road vehicles category were the largest contributor, with 

about 52 % of the daily NOx emissions. Other mobile categories were again a 

significant component with about 35 % of daily NOx emissions.

3. Despite a significant reduction from the 2002 inventory, pesticide application is still a 

large stationary source of ROG emissions. In the summer of 2009 it will emit 3.5 tpd

of ROG. See the detailed ROG Summer Planning Inventory list under Area-Wide 

Solvent Evaporation.

4. The largest source of NOx emissions for the summer planning inventory was the 

mobile source category, which will emit approximately 28 tpd or approximately 87 

% of the total NOx emissions in 2009.
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CHAPTER 6 – EMISSION FORECAST Page 49 of 63

Table 6-3 

EMISSIONS BY MAJOR SOURCE CATEGORY

2009 SUMMER PLANNING INVENTORY (tons/day)

Source Category ROG % 

TOTAL

NOX % 

TOTAL

Stationary Sources

Fuel Combustion 0.12 0.38 3.40 10.60

Waste Disposal 0.02 0.06 0.00 0.00

Cleaning and Surface Coatings 0.42 1.33 0.00 0.00

Petroleum Prod. and Marketing 0.72 2.28 0.00 0.00

Industrial Processes 0.07 0.22 0.04 0.12

Total Stationary Sources 1.35 4.27 3.44 10.72

Area-wide Sources

Solvent Evaporation 7.25 a 22.92 0.00 0.00

Miscellaneous Processes 8.04 25.42 0.89 2.77

Total Area-Wide Sources 15.29 48.34 0.89 2.77

Mobile Sources

On-Road Motor Vehicles 6.76 21.37 16.53 51.51

Off-Road Vehicles 8.23 26.02 11.23 35.00

Total Mobile Sources 14.99 47.39 27.76 86.51

Total for Imperial 31.63 100.00 32.09 100.00 a Under the detailed Summer Planning inventory list for ROG the Pesiticides/Fertilizers fall under the Area-Wide section.

6.5 EMISSION INVENTORY TRENDS

A comparison of 2002 and 2009 ROG and NOx summer planning inventories is 

summarized in Table 6-4. The emission reductions as illustrated in Table 6-4 reflect the 

difference in emissions resulting from the adoption and implementation of rules adopted

prior to December of 2009. ROG summer planning emissions should decrease by 5.69

tpd or 15.24% in 2009 compared to the 2002 base year. In addition, NOx summer 

planning emissions should decrease by 5.35 tpd or 14.29 % for the same year period. 

Table 6-4

IMPERIAL COUNTY SUMMER PLANNING

EMISSIONS INVENTORY COMPARISON

ROG

Tons per Day Reductions

2002-2009

2002 2009 Tons 

per day

Percent

Stationary 1.28 1.35

5.69 15.24

Area-Wide 20.82 15.29

On-Road Mobile 8.77 6.76

Off-Road Mobile 6.45 8.23

Total ROG 37.32 31.63
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CHAPTER 6 – EMISSION FORECAST Page 50 of 63

Table 6-4

IMPERIAL COUNTY SUMMER PLANNING

EMISSIONS INVENTORY COMPARISON

NOx

Tons per Day Reductions

2002-2009

2002 2009 Tons 

per day

Percent

Stationary 3.60 3.44

5.34 14.27

Area-Wide 0.92 0.89

On-Road Mobile 20.21 16.53

Off-Road Mobile 12.70 11.23

Total NOx 37.43 32.09

6.6 TRANSPORTATION CONFORMITY

Transportation conformity is a CAA provision which requires transportation planning 

agencies to demonstrate that their transportation plans, funding programs, and projects 

are conforming to an adopted SIP. One manner in which conformity may be 

demonstrated is a comparison, by transportation planning agencies, of vehicle 

emissions from transportation plans to emissions budgets in an adopted SIP. An 

emissions budget is reflective of the level of emissions from on-road motor vehicles that 

ensures an area either maintains the NAAQS or makes progress toward clean air.

According to the CAA in nonattainment and maintenance areas conformity means that 

any action will not: (1) cause or contribute to violations of a NAAQS, (2) worsen the 

severity of an existing violation, or (3) delay timely attainment of any NAAQS or any 

interim milestone. Actions involving Federal Highway Administration (FHWA) or Federal 

Transit Administration (FTA) funding or approval are subject to the transportation 

conformity rule (40 CFR part 93, subpart A). Under this rule, metropolitan planning 

organizations (MPOs) in nonattainment and maintenance areas coordinate with state air 

quality and transportation agencies, U.S. EPA, and the FHWA and FTA to demonstrate 

that their metropolitan transportation plans (“plans”) and transportation improvement 

programs (TIP) conform to applicable SIPs. This is typically determined by showing that 

estimated emissions from existing and planned highway and transit systems are less 

than or equal to the motor vehicle emissions budgets (“budgets”) contained in an 

adopted SIP. 

For U.S. EPA to find any budget adequate and approvable, the submittal must meet the 

conformity adequacy requirements of 40 CFR 93.118(e)(4) and be approvable under all 

pertinent SIP requirements. For transportation conformity purposes, the cap on motor 

vehicle emissions is known as the motor vehicle emissions budget. The budget must 

reflect all of the motor vehicle control measures contained in the attainment 

demonstration (40 CFR 93.118(e)(4)(v)). 
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CHAPTER 6 – EMISSION FORECAST Page 51 of 63

On April 16th, 2008, the U.S. EPA found the budgets for VOC and NOx for 2009 from 

the Imperial County 8-hour Ozone Early Progress Plan adequate for use for 

transportation conformity purposes; see http://www.epa.gov/fedrgstr/EPAAIR/2008/May/Day-05/a9821.htm. An early progress plan is an optional plan and must 

simply show some progress toward attainment. As such, the early progress plan was 

designed to show reductions from a base year of 2002 to the year 2009. These 

budgets apply to all future years until a new budget is submitted in a control strategy 

plan. The budgets listed in Table 6-5 are the caps for Imperial County transportation 

planning efforts.

Table 6-5 

2009 Imperial County VOC and NOx Budgets, tons per day

Pollutant --> NOx VOC

2009 17 7
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CHAPTER 7 – CONCLUSIONS AND SIP CHECKLIST Page 52 of 63

CHAPTER 7

CONCLUSIONS AND SIP CHECKLIST

7.1 CHECKLIST OF SIP REQUIREMENTS
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CHAPTER 7 – CONCLUSIONS AND SIP CHECKLIST Page 53 of 63

CHAPTER 7 – CONCLUSION AND SIP CHECKLIST

7.1 CHECKLIST OF SIP REQUIREMENTS AND CONCLUSIONS

A checklist of the 8-hour ozone SIP requirements pertinent to the Modified AQMP (as 

outlined both in the U.S. EPA general SIP guidelines for ozone Part D for “moderate” 

non-attainment areas and the final rule of Determination of Attainment of the 1997 8-

hour ozone NAAQS for Imperial County, 74FR 63309, December 3, 2009) is presented 

in Table 7.1.5 Because the U.S. EPA made a final determination that Imperial County 

attained the 1997 8-hour ozone NAAQS in 2006-2008 the ruling effectively suspended

the following requirements: an attainment demonstration, a RFP plan, contingency 

measures, and other planning SIP requirements. As documented in Table 7.1, all 

remaining SIP requirements applicable to the Modified AQMP have been successfully 

addressed.

Table 7.1

STATE IMPLEMENTATION PLAN CHECKLIST

Required Element Document Location Comments

Attainment Demonstration, 

(CAA, Section182(b)(1))

Not Required

Subpart 1 Reasonable 

Available Control Measures 

(RACM), (CAA, Section 

172(c)(1))

Not Required

RFP (CAA, Sections 

172(c)(2), 182(b)(1))

Not Required

Emissions Inventory, (CAA, 

Sections 172(c)(3) and 

182(a)(1))

Chapter 4 This chapter explains the 2002 

emissions inventory which has 

been designated as the baseline 

for measuring progress toward 

attainment of the 8-hour ozone 

NAAQS. The pollutants included 

in the emissions inventory are 

reactive organic compounds 

(ROG) and oxides of nitrogen 

(NOx), both precursors to ozone 

formation.

New Source Review (CAA, 

Sections172(c)(4) and (5); 

and 182(a)(2)(C)

Chapter 5 There are two versions of NSR 

rule that are enforced by the 

ICAPCD. A current version 

adopted as an amendment by 

the ICAPCD Air Board on 

October 10, 2006 and a SIP 

version of Rule 207, Standards 

 

5 See Appendix A for a copy of the Federal Register Notice 74FR 63309 dated December 3, 2009.
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CHAPTER 7 – CONCLUSIONS AND SIP CHECKLIST Page 54 of 63

Table 7.1

STATE IMPLEMENTATION PLAN CHECKLIST

Required Element Document Location Comments

for Permit to Construct, 

approved on November 10, 

1980. Both versions of Rule 207 

fulfill the requirements of CAA 

Sections 172(c)(4) and (5), 

182(a)(2)(C) and the 1.15 to 1 

offset ratio required by Sections 

182(a)(4) and 182(b)(5).

Contingency Measures 

(CAA, Section 172(c)(9)

Not Required

Subpart 2 RACT for VOCs 

and NOx, (CAA, Sections 

182(b)(2), 182(f))

Chapter 5 This chapter explains the overall 

State and local control 

strategies. The local component 

of the control strategy consists of 

Reasonably Available Control 

Measures (RACM) which are 

essentially cost effective 

stationary source control 

measures. The EPA established 

stationary source control 

measures and introduced the 

control measures via Control 

Technique Guidance (CTG) 

documents. When rules are 

adopted and are in conformance 

with CTG documents RACT 

requirements as prescribed by 

the CAA are typically fulfilled. A 

more complete analysis can be 

found in the 2009 RACT SIP for 

Imperial County which is 

concurrently adopted with the 

Modified AQMP. 

Vehicle Inspection and 

Maintenance (I/M), (CAA, 

Sections 182(a)(2)(B), 

(b)(4))

Not Applicable to Imperial 

County because population 

below 200,000.

Periodic Inventory, (CAA, 

Section 182(a)(3)(A))

Chapter 6 This chapter explains the 

forecasted inventory to year 

2009 and it takes into account 

projected socioeconomic growth 

and the emission reductions 
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CHAPTER 7 – CONCLUSIONS AND SIP CHECKLIST Page 55 of 63

Table 7.1

STATE IMPLEMENTATION PLAN CHECKLIST

Required Element Document Location Comments

anticipated from ICAPCD rules 

and State control measures 

adopted prior to 2007. 

Emissions Statement Rule, 

(CAA, Section 182(a)(3)(B))

ICAPCD Rule 116, Emissions 

Statement and Certification, 

adopted on February 23, 2010.

Offset Ratio 1.15 to 1 (CAA, 

Sections 182(a)(4) and 

182(b)(5))

Chapter 5 As explained in Chapter 5, there 

are two versions of NSR rule 

that are enforced by the 

ICAPCD. A current version 

adopted as an amendment by 

the ICAPCD Air Board on 

October 10, 2006 and a SIP 

version of Rule 207, Standards 

for Permit to Construct, 

approved on November 10, 

1980. Both versions of Rule 207 

fulfill the 1.15 to 1 offset ratio 

required by CAA, Sections 

182(a)(4) and 182(b)(5).

Stage 2 Gasoline Vapor 

Recovery (GVR), (CAA, 

Section 182(b)(3))

Stage 2 GVR requirements no 

longer apply to moderate areas 

following promulgation of 

Onboard Refueling Vapor 

Recovery rule. CAA 202(a)(6); 

59 FR 16262, April 6, 1994.
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APPENDIX A - EPA FINAL RULEMAKING Page 56 of 63

APPENDIX A

APPROVAL AND PROMULGATION OF AIR 

QUALITY IMPLEMENTATION PLANS; 

CALIFORNIA DETERMINATION OF ATTAINMENT 

OF THE 1997 8-HOUR OZONE STANDARD

EPA FINAL RULEMAKING

74FR 63309 – 63310, DECEMBER 3, 2009
Federal Register / Vol. 74, No. 231 / Thursday, December 3, 2009 / Rules and Regulations 63309 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R09–OAR–2009–0188; FRL–9086–7] 

Approval and Promulgation of Air 

Quality Implementation Plans; 

California; Determination of Attainment 

of the 1997 8-Hour Ozone Standard 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: The EPA is determining that 

the Imperial County, California 

moderate 8-hour ozone nonattainment 

area has attained the 1997 8-hour 

National Ambient Air Quality Standard 

(NAAQS) for ozone. This determination 

is based upon certified ambient air 

monitoring data that show the area has 

monitored attainment of the 8-hour 

ozone NAAQS since the 2006–2008 

monitoring period. In addition, quality 

controlled and quality assured ozone 

data for 2008 that are available in the 

EPA Air Quality System database, but 

not yet certified, show that this area 

continues to attain the 1997 8-hour 

ozone NAAQS. This determination 

suspends the requirements for 

California to submit an attainment 

demonstration, a reasonable further 

progress plan, contingency measures, 

and other planning State 

Implementation Plans for this area 

related to attainment of the 8-hour 

ozone NAAQS. These requirements 

shall remain suspended for so long as 

the area continues to attain the ozone 

NAAQS. 

DATES: Effective Date: This rule is 

effective on January 4, 2010. 

ADDRESSES: EPA has established a 

docket for this action under Docket 

Identification No. EPA–R09–OAR– 

2009–0188. All documents in the docket 

are listed on the http:// 

www.regulations.gov Web site. Although 

listed in the index, some information is 

not publicly available, i.e., CBI or other 

information whose disclosure is 

restricted by statute. Certain other 

material, such as copyrighted material, 

is not placed on the Internet and will be 

publicly available only in hard copy 

form. Publicly available docket 

materials are available either 

electronically through http:// 

www.regulations.gov or in hard copy at 

the Air Planning Office, U.S. 

Environmental Protection Agency, 75 

Hawthorne Street, San Francisco, CA 

94105–3901. EPA requests that if at all 

possible, you contact the contact listed 

in the FOR FURTHER INFORMATION

CONTACT section to schedule your 

inspection. The Regional Office’s 

official hours of business are Monday 

through Friday, 8 to 4:55, excluding 

Federal holidays. 

FOR FURTHER INFORMATION CONTACT: 

Wienke Tax, Air Planning Office, U.S. 

Environmental Protection Agency 

Region 9, 75 Hawthorne Street, San 

Francisco, CA 94105–3901, telephone 

number (415) 947–4192, fax number 

(415) 947–3579, electronic mail 

Tax.wienke@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Throughout this document whenever 

‘‘we,’’ ‘‘us,’’ or ‘‘our’’ is used, we mean 

EPA. 

Table of Contents 

I. What Action Is EPA Taking? 

II. What Is the Effect of This Action? 

III. Final Action 

IV. Statutory and Executive Order Reviews 

I. What Action Is EPA Taking? 

EPA is determining that the Imperial 

County, California moderate 8-hour 

ozone nonattainment area has attained 

the 1997 8-hour National Ambient Air 

Quality Standard (NAAQS) for ozone. 

This determination is based upon 

certified ambient air monitoring data 

that show the area has monitored 

attainment of the 1997 ozone NAAQS 

since the 2006–2008 monitoring period. 

In addition, quality controlled and 

quality assured ozone data for 2009 that 

are available in the EPA Air Quality 

System (AQS) database, but not yet 

certified, show that this area continues 

to attain the ozone NAAQS. 

Other specific requirements of the 

determination and the rationale for 

EPA’s proposed action are explained in 

the Notice of Proposed Rulemaking 

(NPR) published on September 23, 2009 

(74 FR 48495) and will not be restated 

here. EPA received no public comments 

on the NPR. 

II. What Is the Effect of This Action? 

Under the provisions of EPA’s ozone 

implementation rule (see 40 CFR 

51.918), this determination suspends 

the requirements for the Imperial 

County, California moderate ozone 

nonattainment area to submit an 

attainment demonstration, a reasonable 

further progress plan, section 172(c)(9) 

contingency measures, and any other 

planning State Implementation Plans 

(SIPs) related to attainment of the 1997 

8-hour ozone NAAQS for so long as the 

area continues to attain the 1997 ozone 

NAAQS. 

This action does not constitute a 

redesignation to attainment under CAA 

section 107(d)(3), because the area does 

not have an approved maintenance plan 

as required under section 175A of the 

CAA, nor a determination that the area 

has met the other requirements for 

redesignation. The classification and 

designation status of the area remains 

moderate nonattainment for the 1997 

8-hour ozone NAAQS until such time as 

EPA determines that it meets the CAA 

requirements for redesignation to 

attainment. 

If EPA subsequently determines, after 

notice-and-comment rulemaking in the 

Federal Register, that the area has 

violated the 1997 8-hour ozone 

standard, the basis for the suspension of 

these requirements would no longer 

exist, and the area would thereafter have 

to address the pertinent requirements. 

III. Final Action 

EPA is determining that the Imperial 

County, California 8-hour ozone 

nonattainment area has attained the 

1997 8-hour ozone standard and 

continues to attain the standard based 

on data through the 2009 ozone season. 

As provided in 40 CFR 51.918, this 

determination suspends the 

requirements for California to submit an 

attainment demonstration, a reasonable 

further progress plan, and contingency 

measures under section 172(c)(9), and 

any other planning SIP related to 

attainment of the 1997 8-hour ozone 

NAAQS for this area, for so long as the 

area continues to attain the standard. 

V. Statutory and Executive Order 

Reviews 

Under Executive Order 12866 (58 FR 

51735, October 4, 1993), this action is 

not a ‘‘significant regulatory action’’ and 

therefore is not subject to review by the 

Office of Management and Budget. For 

this reason, this action is also not 

subject to Executive Order 13211, 

‘‘Actions Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution, or Use’’ (66 FR 28355, May 

22, 2001). This action makes a 

determination based on air quality data, 

and results in the suspension of certain 

Federal requirements. Accordingly, the 

Administrator certifies that this rule 

will not have a significant economic 

impact on a substantial number of small 

entities under the Regulatory Flexibility 

Act (5 U.S.C. 601 et seq.). Because this 

rule makes a determination based on air 

quality data, and results in the 

suspension of certain Federal 

requirements, it does not contain any 

unfunded mandate or significantly or 

uniquely affect small governments, as 

described in the Unfunded Mandates 

Reform Act of 1995 (Pub. L. 104–4). 

This rule also does not have tribal 

implications because it will not have a 

substantial direct effect on one or more 


jlentini on DSKJ8SOYB1PROD with RULES

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ADOPTED JULY 13, 2010

APPENDIX A Page 57 of 63
63310 Federal Register / Vol. 74, No. 231 / Thursday, December 3, 2009 / Rules and Regulations 

Indian tribes, on the relationship 

between the Federal Government and 

Indian tribes, or on the distribution of 

power and responsibilities between the 

Federal Government and Indian tribes, 

as specified by Executive Order 13175 

(59 FR 22951, November 9, 2000). This 

action also does not have Federalism 

implications because it does not have 

substantial direct effects on the States, 

on the relationship between the national 

government and the States, or on the 

distribution of power and 

responsibilities among the various 

levels of government, as specified in 

Executive Order 13132 (64 FR 43255, 

August 10, 1999), because it merely 

makes a determination based on air 

quality data and results in the 

suspension of certain Federal 

requirements, and does not alter the 

relationship or the distribution of power 

and responsibilities established in the 

Clean Air Act. This rule also is not 

subject to Executive Order 13045 

‘‘Protection of Children from 

Environmental Health Risks and Safety 

Risks’’ (62 FR 19885, April 23, 1997), 

because it determines that air quality in 

the affected area is meeting Federal 

standards. 

The requirements of section 12(d) of 

the National Technology Transfer and 

Advancement Act of 1995 (15 U.S.C. 

272 note) do not apply because it would 

be inconsistent with applicable law for 

EPA, when determining the attainment 

status of an area, to use voluntary 

consensus standards in place of 

promulgated air quality standards and 

monitoring procedures that otherwise 

satisfy the provisions of the Clean Air 

Act. 

This rule does not impose an 

information collection burden under the 

provisions of the Paperwork Reduction 

Act of 1995 (44 U.S.C. 3501 et seq.) 

Under Executive Order 12898, EPA 

finds that this rule involves a 

determination of attainment based on 

air quality data and will not have 

disproportionately high and adverse 

human health or environmental effects 

on any communities in the area, 

including minority and low-income 

communities. 

The Congressional Review Act, 5 

U.S.C. 801 et seq., as added by the Small 

Business Regulatory Enforcement 

Fairness Act of 1996, generally provides 

that before a rule may take effect, the 

agency promulgating the rule must 

submit a rule report, which includes a 

copy of the rule, to each House of the 

Congress and to the Comptroller General 

of the United States. EPA will submit a 

report containing this rule and other 

required information to the U.S. Senate, 

the U.S. House of Representatives, and 

the Comptroller General of the United 

States prior to publication of the rule in 

the Federal Register. A major rule 

cannot take effect until 60 days after it 

is published in the Federal Register. 

This action is not a ‘‘major rule’’ as 

defined by 5 U.S.C. 804(2). 

Under section 307(b)(1) of the Clean 

Air Act, petitions for judicial review of 

this action must be filed in the United 

States Court of Appeals for the 

appropriate circuit by May 19, 2008. 

Filing a petition for reconsideration by 

the Administrator of this final rule does 

not affect the finality of this rule for the 

purposes of judicial review nor does it 

extend the time within which a petition 

for judicial review may be filed, and 

shall not postpone the effectiveness of 

such rule or action. This action may not 

be challenged later in proceedings to 

enforce its requirements. (See section 

307(b)(2).) 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Incorporation by 

reference, Intergovernmental relations, 

Nitrogen dioxide, Ozone, Reporting and 

recordkeeping requirements, Volatile 

organic compounds. 

Dated: November 13, 2009. 

Laura Yoshii, 

Acting Regional Administrator, 

Region IX. 

■ Part 52 of chapter I, title 40 of the 

Code of Federal Regulations is amended 

as follows: 

PART 52—[AMENDED] 

■ 1. The authority citation for part 52 

continues to read as follows: 

Authority: 42 U.S.C. 7401 et seq. 

Subpart F—California 

■ 2. Section 52.282 is amended by 

adding paragraph (c) to read as follows: 

§ 52.282 Control strategy and regulations: 

Ozone. 

* * * * * 

(c) Determination of attainment. 

Effective January 4, 2010, EPA is 

determining that the Imperial County, 

California 8-hour ozone nonattainment 

area has attained the 1997 8-hour ozone 

standard. Under the provisions of EPA’s 

ozone implementation rule (see 40 CFR 

51.918), this determination suspends 

the reasonable further progress and 

attainment demonstration requirements 

of section 182(b)(1) and related 

requirements of section 172(c)(9) of the 

Clean Air Act for as long as the area 

does not monitor any violations of the 

8-hour ozone standard. If a violation of 

the 1997 ozone NAAQS is monitored in 

the Imperial County, California 8-hour 

ozone nonattainment area, this 

determination shall no longer apply. 

[FR Doc. E9–28536 Filed 12–2–09; 8:45 am] 

BILLING CODE 6560–50–P 

DEPARTMENT OF TRANSPORTATION 

Pipeline and Hazardous Materials 

Safety Administration 

49 CFR Parts 192 and 195 

[Docket ID PHMSA–2007–27954; Amdt. Nos. 

192–112 and 195–93] 

RIN 2137–AE28 

Pipeline Safety: Control Room 

Management/Human Factors 

AGENCY: Pipeline and Hazardous 

Materials Safety Administration 

(PHMSA); DOT. 

ACTION: Final rule. 

SUMMARY: PHMSA is amending the 

Federal pipeline safety regulations to 

address human factors and other aspects 

of control room management for 

pipelines where controllers use 

supervisory control and data acquisition 

(SCADA) systems. Under the final rule, 

affected pipeline operators must define 

the roles and responsibilities of 

controllers and provide controllers with 

the necessary information, training, and 

processes to fulfill these 

responsibilities. Operators must also 

implement methods to prevent 

controller fatigue. The final rule further 

requires operators to manage SCADA 

alarms, assure control room 

considerations are taken into account 

when changing pipeline equipment or 

configurations, and review reportable 

incidents or accidents to determine 

whether control room actions 

contributed to the event. 

Hazardous liquid and gas pipelines 

are often monitored in a control room by 

controllers using computer-based 

equipment, such as a SCADA system, 

that records and displays operational 

information about the pipeline system, 

such as pressures, flow rates, and valve 

positions. Some SCADA systems are 

used by controllers to operate pipeline 

equipment, while, in other cases, 

controllers may dispatch other 

personnel to operate equipment in the 

field. These monitoring and control 

actions, whether via SCADA system 

commands or direction to field 

personnel, are a principal means of 

managing pipeline operation. 

This rule improves opportunities to 

reduce risk through more effective 

control of pipelines. It further requires 


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FINAL 2009 1997 8-HOUR OZONE MODIFIED AQMP

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APPENDIX B – DETAILED EMISSIONS INVENTORY Page 59 of 63

APPENDIX B

NOx AND ROG

DETAILED EMISSIONS INVENTORY
SUBCATEGORY 2002 2005 2006 2008 2009 2010 2011 2012 2013 2014 2015 2017 2018 2020 2023

STATIONARY

Fuel Combustion

ELECTRIC UTILITIES 1.42 1.42 1.42 1.42 1.42 1.42 1.42 1.42 1.42 1.42 1.42 1.42 1.42 1.42 1.42

MANUFACTURING AND INDUSTRIAL 1.27 1.22 1.21 1.12 1.11 1.10 1.11 1.10 1.09 1.08 1.09 1.08 1.07 1.05 1.03

FOOD AND AGRICULTURAL PROCESSING 0.71 0.70 0.69 0.67 0.67 0.66 0.65 0.65 0.65 0.64 0.64 0.62 0.61 0.59 0.56

SERVICE AND COMMERCIAL 0.02 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03

OTHER (FUEL COMBUSTION) 0.15 0.16 0.16 0.17 0.17 0.17 0.18 0.18 0.18 0.19 0.19 0.19 0.20 0.20 0.21

TOTAL FUEL COMBUSTION 3.57 3.53 3.51 3.41 3.40 3.38 3.38 3.38 3.37 3.35 3.36 3.34 3.33 3.29 3.25

Waste Disposal

OTHER (WASTE DISPOSAL) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

TOTAL WASTE DISPOSAL

Cleaning and Surface Coatings

LAUNDERING 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

DEGREASING 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

COATINGS AND RELATED PROCESS SOLVENTS 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

ADHESIVES AND SEALANTS 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

TOTAL CLEANING AND SURFACE COATINGS

Petroleum Production and Marketing

PETROLEUM REFINING 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

PETROLEUM MARKETING 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

OTHER (PETROLEUM PRODUCTION AND MARKETING 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

TOTAL PETROLEUM PRODUCTION AND MARKETING

Industrial Processes

FOOD AND AGRICULTURE 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

MINERAL PROCESSES 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

METAL PROCESSES 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

OTHER (INDUSTRIAL PROCESSES) 0.02 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03

TOTAL INDUSTRIAL PROCESES 0.03 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.05 0.05

STATIONARY SUBTOTAL 3.60 3.56 3.55 3.44 3.44 3.42 3.42 3.42 3.41 3.40 3.40 3.38 3.37 3.33 3.30

AREA-WIDE

Solvent Evaporation

CONSUMER PRODUCTS 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

ARCHITECTURAL COATINGS AND RELATED PROCES 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

PESTICIDES/FERTILIZERS 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

ASPHALT PAVING / ROOFING 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

TOTAL SOLVENT EVAPORATION

Miscellaneous Processes

RESIDENTIAL FUEL COMBUSTION 0.06 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07

FARMING OPERATIONS 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

CONSTRUCTION AND DEMOLITION 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

PAVED ROAD DUST 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

UNPAVED ROAD DUST 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

NOx -IMPERIAL COUNTY - SUMMER PLANNING INVENTORY - ADJUSTED FOR MEASURES AND CATEGORIES THROUGH 31 DEC 2006

APPENDIX B Page 60 of 63
SUBCATEGORY 2002 2005 2006 2008 2009 2010 2011 2012 2013 2014 2015 2017 2018 2020 2023

NOx -IMPERIAL COUNTY - SUMMER PLANNING INVENTORY - ADJUSTED FOR MEASURES AND CATEGORIES THROUGH 31 DEC 2006

FUGITIVE WINDBLOWN DUST 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

FIRES 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

MANAGED BURNING AND DISPOSAL 0.85 0.84 0.83 0.82 0.82 0.81 0.81 0.81 0.80 0.80 0.79 0.78 0.78 0.77 0.75

COOKING 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

TOTAL MISCELLANEOUS PROCESSES 0.92 0.90 0.90 0.89 0.89 0.88 0.88 0.87 0.87 0.87 0.86 0.85 0.85 0.84 0.83

AREA-WIDE SUBTOTAL 0.92 0.90 0.90 0.89 0.89 0.88 0.88 0.87 0.87 0.87 0.86 0.85 0.85 0.84 0.83

ON-ROAD MOBILE

LIGHT DUTY PASSENGER (LDA) 2.98 2.51 2.39 2.16 2.10 2.03 1.95 1.90 1.85 1.80 1.76 1.69 1.67 1.66 1.66

LIGHT DUTY TRUCKS - 1 (LDT1) 1.57 1.25 1.18 1.02 1.01 0.98 0.95 0.91 0.88 0.84 0.79 0.68 0.62 0.51 0.38

LIGHT DUTY TRUCKS - 2 (LDT2) 1.36 1.35 1.30 1.22 1.19 1.16 1.12 1.07 1.02 0.97 0.91 0.80 0.75 0.65 0.53

MEDIUM DUTY TRUCKS (MDV) 0.33 0.42 0.41 0.41 0.40 0.39 0.38 0.37 0.37 0.36 0.35 0.32 0.31 0.27 0.23

LIGHT HEAVY DUTY GAS TRUCKS - 1 (LHDV1) 0.06 0.06 0.07 0.07 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.07 0.07 0.07

LIGHT HEAVY DUTY GAS TRUCKS - 2 (LHDV2) 0.09 0.07 0.07 0.06 0.06 0.05 0.05 0.05 0.04 0.04 0.04 0.04 0.04 0.03 0.03

MEDIUM HEAVY DUTY GAS TRUCKS (MHDV) 0.15 0.13 0.13 0.11 0.11 0.11 0.10 0.09 0.08 0.07 0.06 0.05 0.05 0.04 0.03

HEAVY HEAVY DUTY GAS TRUCKS (HHDV) 0.13 0.12 0.11 0.10 0.10 0.10 0.10 0.09 0.09 0.08 0.08 0.07 0.07 0.07 0.07

LIGHT HEAVY DUTY DIESEL TRUCKS - 1 (LHDV1) 0.01 0.10 0.12 0.14 0.13 0.12 0.11 0.10 0.09 0.08 0.07 0.06 0.05 0.05 0.04

LIGHT HEAVY DUTY DIESEL TRUCKS - 2 (LHDV2) 0.10 0.11 0.10 0.10 0.10 0.10 0.09 0.08 0.08 0.07 0.06 0.05 0.05 0.04 0.03

MEDIUM HEAVY DUTY DIESEL TRUCKS (MHDV) 0.69 0.63 0.61 0.59 0.59 0.55 0.52 0.47 0.42 0.38 0.34 0.26 0.23 0.19 0.15

HEAVY HEAVY DUTY DIESEL TRUCKS (HHDV) 12.48 8.98 11.41 10.82 10.38 9.66 8.95 8.22 7.49 6.77 6.14 4.90 4.45 3.84 3.39

MOTORCYCLES (MCY) 0.02 0.05 0.06 0.06 0.06 0.06 0.06 0.06 0.07 0.07 0.07 0.07 0.07 0.08 0.08

HEAVY DUTY DIESEL URBAN BUSES (UB) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

HEAVY DUTY GAS URBAN BUSES (UB) 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

SCHOOL BUSES (SB) 0.07 0.09 0.09 0.09 0.09 0.09 0.09 0.09 0.10 0.10 0.10 0.11 0.12 0.12 0.13

OTHER BUSES (OB) 0.09 0.09 0.08 0.08 0.08 0.07 0.07 0.07 0.06 0.06 0.06 0.05 0.05 0.04 0.03

MOTOR HOMES (MH) 0.07 0.06 0.05 0.05 0.05 0.05 0.05 0.05 0.04 0.04 0.04 0.04 0.03 0.03 0.02

ON-ROAD SUBTOTAL 20.21 16.02 18.19 17.07 16.53 15.60 14.67 13.71 12.76 11.81 10.95 9.27 8.63 7.68 6.86

OTHER MOBILE

AIRCRAFT 0.79 0.79 0.69 1.43 1.82 2.17 2.52 2.87 3.21 3.27 3.33 3.33 3.33 3.33 3.33

TRAINS 6.98 5.82 5.47 5.28 5.30 3.92 4.02 4.11 4.20 4.30 4.40 4.61 4.73 4.97 5.38

RECREATIONAL BOATS 0.32 0.40 0.42 0.43 0.43 0.43 0.43 0.42 0.42 0.42 0.42 0.43 0.43 0.43 0.42

OFF-ROAD RECREATIONAL VEHICLES 0.06 0.07 0.07 0.08 0.08 0.09 0.09 0.09 0.10 0.10 0.11 0.11 0.12 0.13 0.14

OFF-ROAD EQUIPMENT 1.77 1.69 1.60 1.52 1.48 1.44 1.41 1.37 1.34 1.28 1.22 1.11 1.06 0.97 0.88

FARM EQUIPMENT 2.78 2.52 2.44 2.21 2.11 2.04 1.94 1.81 1.68 1.57 1.46 1.24 1.14 0.96 0.75

FUEL STORAGE AND HANDLING 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

OFF-ROAD SUB-TOTAL 12.70 11.29 10.69 10.96 11.23 10.09 10.40 10.68 10.95 10.95 10.94 10.83 10.80 10.79 10.90

TOTAL INVENTORY 37.43 31.77 33.33 32.37 32.08 29.99 29.36 28.68 27.99 27.02 26.16 24.34 23.64 22.64 21.88

APPENDIX B Page 61 of 63
SUBCATEGORY 2002 2005 2006 2008 2009 2010 2011 2012 2013 2014 2015 2017 2018 2020 2023

STATIONARY

Fuel Combustion

ELECTRIC UTILITIES 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04

MANUFACTURING AND INDUSTRIAL 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03

FOOD AND AGRICULTURAL PROCESSING 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04

SERVICE AND COMMERCIAL 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

OTHER (FUEL COMBUSTION) 0.01 0.01 0.01 0.01 0.01 0.01 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02

TOTAL FUEL COMBUSTION 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12

Waste Disposal

OTHER (WASTE DISPOSAL) 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02

TOTAL WASTE DISPOSAL 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02

Cleaning and Surface Coatings

LAUNDERING 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

DEGREASING 0.20 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.20

COATINGS AND RELATED PROCESS SOLVENTS 0.15 0.16 0.16 0.16 0.17 0.17 0.17 0.17 0.17 0.18 0.18 0.18 0.18 0.18 0.19

ADHESIVES AND SEALANTS 0.06 0.06 0.06 0.06 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.04 0.04

TOTAL CLEANING AND SURFACE COATINGS 0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.43 0.43 0.43 0.43 0.44

Petroleum Production and Marketing

PETROLEUM REFINING 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

PETROLEUM MARKETING 0.64 0.68 0.69 0.70 0.71 0.71 0.71 0.73 0.73 0.74 0.75 0.76 0.76 0.78 0.79

OTHER (PETROLEUM PRODUCTION AND MARKETING 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

TOTAL PETROLEUM PRODUCTION AND MARKETING 0.65 0.69 0.70 0.71 0.72 0.72 0.72 0.74 0.74 0.75 0.76 0.77 0.78 0.79 0.81

Industrial Processes

FOOD AND AGRICULTURE 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

MINERAL PROCESSES 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

METAL PROCESSES 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

OTHER (INDUSTRIAL PROCESSES) 0.06 0.06 0.06 0.06 0.06 0.06 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.08 0.08

TOTAL INDUSTRIAL PROCESSES 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.08 0.08 0.08 0.08 0.08 0.08 0.09 0.09

STATIONARY SUBTOTAL 1.28 1.31 1.32 1.33 1.35 1.35 1.36 1.38 1.38 1.40 1.41 1.43 1.44 1.46 1.48

AREA-WIDE

Solvent Evaporation

CONSUMER PRODUCTS 1.16 1.10 1.10 1.08 1.09 1.11 1.13 1.15 1.17 1.19 1.21 1.25 1.28 1.32 1.39

ARCHITECTURAL COATINGS AND RELATED PROCESS 0.62 0.60 0.55 0.57 0.58 0.59 0.59 0.60 0.61 0.62 0.63 0.64 0.65 0.67 0.70

PESTICIDES/FERTILIZERS 5.26 4.04 3.45 3.45 3.45 3.45 3.45 3.45 3.45 3.45 3.45 3.45 3.45 3.45 3.45

ASPHALT PAVING / ROOFING 1.96 2.05 2.08 2.12 2.13 2.15 2.16 2.17 2.17 2.18 2.19 2.21 2.21 2.22 2.24

TOTAL SOLVENT EVAPORATION 9.01 7.79 7.19 7.21 7.25 7.29 7.33 7.37 7.40 7.45 7.48 7.55 7.59 7.66 7.78

Miscellaneous Processes

RESIDENTIAL FUEL COMBUSTION 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

FARMING OPERATIONS 9.47 6.99 8.21 5.78 5.78 5.78 5.78 5.78 5.78 5.78 5.78 5.78 5.78 5.78 5.78

CONSTRUCTION AND DEMOLITION 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

PAVED ROAD DUST 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

UNPAVED ROAD DUST 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

FUGITIVE WINDBLOWN DUST 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

FIRES 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

ROG - IMPERIAL - SUMMER PLANNING INVENTORY -- ADJUSTED FOR MEASURES AND CATEGORIES THROUGH 31 DEC 2006

APPENDIX B Page 62 of 63
SUBCATEGORY 2002 2005 2006 2008 2009 2010 2011 2012 2013 2014 2015 2017 2018 2020 2023

ROG - IMPERIAL - SUMMER PLANNING INVENTORY -- ADJUSTED FOR MEASURES AND CATEGORIES THROUGH 31 DEC 2006

MANAGED BURNING AND DISPOSAL 2.32 2.28 2.26 2.24 2.23 2.22 2.20 2.19 2.18 2.17 2.16 2.13 2.12 2.09 2.06

COOKING 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.03

TOTAL MISCELLANEOUS PROCESSES 11.81 9.30 10.50 8.05 8.04 8.03 8.02 8.01 7.99 7.98 7.97 7.95 7.94 7.91 7.88

AREA-WIDE SUBTOTAL 20.82 17.08 17.69 15.27 15.29 15.32 15.35 15.37 15.40 15.43 15.45 15.50 15.53 15.57 15.65

ON-ROAD MOBILE

LIGHT DUTY PASSENGER (LDA) 4.08 3.42 3.24 2.90 2.78 2.66 2.53 2.44 2.34 2.25 2.18 2.05 1.99 1.92 1.85

LIGHT DUTY TRUCKS - 1 (LDT1) 1.74 1.48 1.43 1.31 1.30 1.28 1.26 1.23 1.20 1.16 1.11 0.99 0.92 0.80 0.65

LIGHT DUTY TRUCKS - 2 (LDT2) 1.14 1.12 1.10 1.05 1.04 1.02 1.00 0.97 0.95 0.93 0.89 0.83 0.81 0.76 0.70

MEDIUM DUTY TRUCKS (MDV) 0.22 0.28 0.27 0.27 0.27 0.27 0.26 0.27 0.27 0.28 0.28 0.29 0.30 0.30 0.29

LIGHT HEAVY DUTY GAS TRUCKS - 1 (LHDV1) 0.08 0.06 0.06 0.05 0.04 0.04 0.04 0.04 0.03 0.03 0.03 0.03 0.03 0.03 0.03

LIGHT HEAVY DUTY GAS TRUCKS - 2 (LHDV2) 0.09 0.07 0.06 0.06 0.05 0.05 0.05 0.05 0.04 0.04 0.04 0.03 0.03 0.02 0.02

MEDIUM HEAVY DUTY GAS TRUCKS (MHDV) 0.25 0.20 0.18 0.15 0.15 0.14 0.13 0.11 0.10 0.08 0.07 0.05 0.05 0.03 0.02

HEAVY HEAVY DUTY GAS TRUCKS (HHDV) 0.09 0.07 0.07 0.05 0.05 0.04 0.04 0.04 0.03 0.03 0.03 0.03 0.01 0.01 0.01

LIGHT HEAVY DUTY DIESEL TRUCKS - 1 (LHDV1) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

LIGHT HEAVY DUTY DIESEL TRUCKS - 2 (LHDV2) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

MEDIUM HEAVY DUTY DIESEL TRUCKS (MHDV) 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.00 0.00

HEAVY HEAVY DUTY DIESEL TRUCKS (HHDV) 0.84 0.62 0.78 0.74 0.71 0.67 0.62 0.58 0.54 0.49 0.45 0.38 0.35 0.30 0.28

MOTORCYCLES (MCY) 0.11 0.25 0.27 0.29 0.29 0.30 0.30 0.31 0.31 0.32 0.33 0.34 0.34 0.35 0.36

HEAVY DUTY DIESEL URBAN BUSES (UB) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

HEAVY DUTY GAS URBAN BUSES (UB) 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

SCHOOL BUSES (SB) 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.01 0.01 0.01

OTHER BUSES (OB) 0.05 0.04 0.03 0.03 0.03 0.03 0.03 0.03 0.02 0.02 0.02 0.02 0.02 0.01 0.01

MOTOR HOMES (MH) 0.04 0.04 0.03 0.03 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.01 0.01 0.01 0.00

ON-ROAD SUBTOTAL 8.77 7.68 7.56 6.96 6.76 6.54 6.31 6.10 5.89 5.68 5.48 5.07 4.87 4.54 4.23

OTHER MOBILE

AIRCRAFT 0.91 0.91 0.81 1.47 1.62 1.75 1.88 2.00 2.13 2.25 2.36 2.36 2.36 2.36 2.36

TRAINS 0.53 0.55 0.55 0.54 0.54 0.55 0.55 0.56 0.56 0.57 0.58 0.59 0.60 0.61 0.64

RECREATIONAL BOATS 0.79 0.84 0.83 0.80 0.79 0.77 0.76 0.75 0.75 0.74 0.74 0.74 0.74 0.74 0.75

OFF-ROAD RECREATIONAL VEHICLES 2.65 3.42 3.62 3.86 3.98 4.10 4.24 4.38 4.52 4.68 4.84 5.19 5.37 5.76 6.40

OFF-ROAD EQUIPMENT 0.76 0.81 0.76 0.72 0.71 0.70 0.69 0.69 0.68 0.66 0.65 0.62 0.61 0.60 0.61

FARM EQUIPMENT 0.58 0.54 0.52 0.46 0.44 0.43 0.40 0.37 0.34 0.31 0.29 0.24 0.22 0.19 0.16

FUEL STORAGE AND HANDLING 0.23 0.23 0.22 0.16 0.15 0.14 0.13 0.13 0.12 0.11 0.11 0.10 0.10 0.09 0.09

OFF-ROAD SUB-TOTAL 6.45 7.30 7.31 8.03 8.23 8.43 8.65 8.87 9.10 9.32 9.56 9.83 9.99 10.35 11.00

TOTAL INVENTORY 37.32 33.37 33.88 31.59 31.63 31.65 31.67 31.72 31.77 31.83 31.90 31.84 31.83 31.92 32.37

APPENDIX B Page 63 of 63