### 2007 EMISSIONS INVENTORY UPDATE FOR THE GILA RIVER INDIAN COMMUNITY

Assistance ID No. A-98920909-0 U.S. Environmental ProtectionAgency, Region IX

For Submittal To: Ms. Deborah Jordan U.S. EPA, Region IX 75 Hawthorne Street, Air 

### 1 San Francisco, California 94105

Submitted By: Gila River Indian Comm~~nity Department of Environmental Quality P.O. Box 97 Sacaton, Arizona 85247 (520) 562-2234 (520) 562-2245 Fax Prepared By: Daniel C. Blair Compliance and Enforcement Manager
January 2009

### TABLE OF CONTENTS
1 EXECUTIVE SUMMARY

## ........................................................................................... 1 2 INTRODUCTION

# ....................................................................................................... 2

............................................................................................... 2.1. Background 2 2.2. Study Area

................................................................................................. 3 

### 3 METHODOLOGIES

## ...................................................................................................4 3.1. Point Sources



### ............................................................................................ 4 3.2. Area Sources

............................................................................................. 4

.......................................................................................... 3.3. Mobile Sources 5 4 

### SUMMARY OF RESULTS

# ......................................................................................... 6 5 

### POINT SOURCES

## .................................................................................................... 7 5.1. Ongoing Sources

....................................................................................... 7 5.2. Newsources



### ............................................................................................. 9 5.3. DiscontinuedSources



### ............................................................................ 10 5.4. Facilities Below Permitting And Reporting Thresholds



### ............................ 10 6 

### AREA SOURCES

# .................................................................................................... 12 7 MOBILE SOURCES

## ................................................................................................ 13

................................................................................................... 7.1. Nonroad 13 7.2. Onroad

.................................................................................................... 13 7.2.1. Data Collection



### ........................................................................ 14 7.2.2. Calculation Methods

................................................................. 15 8 

### REFERENCES

## ........................................................................................................ 17
FIGURES 1 Map of the Gila River Indian Community. Arizona 2 Map of Gila River IndianCorrrmunity. Maricopaand PinalCounties. and PMI0 NonAttainment Area 3 Map of AgriculturalAreas on the Gila River Indian Community

### 1 EXECUTIVE SUMMARY This report contains the 2007 Emissions Inventory (El) Update (2007 El) conducted within the exterior boundaries of the Gila River Indian Community (GRIC). An El is an itemized list of emission estimates for sources of air pollution in a given area for a specified time period. This 2007 El is an update to the original El that was developed and submitted for 1997. Therefore, itshould be recognized that emission sources mayfluctuate drastically within the 10- year time frame only to return to their original levels when the next 10-year El update is conducted. Similarly, due to fluctuating market conditions and changestolimplementation of the GRIC Master Plan, emission sources in years preceding and following the El update may be dramatically different (or absent) from the year the El update was completed.. Some sources (e.g., construction) did not significantly contribute to the overall emissions during the years in which the Els were conducted and were, therefore, not included in the 1997 and 2007 Els. The 2007 El includes emissions from point sources, area sources, onroad mobile, nonroad mobile and non-anthropogenic sources of air pollution. The inventory provides emissions estimates for carbon monoxide (CO), nitrogen oxides (NOx), sulfur oxides (SOX),volatile organic compounds (VOCs), and particulate matter less than 10 microns in diameter (PM10). Emissions of lead were not calculated since there are no significant sources emitting ambient lead emissions within the Community and leaded gasoline is no longer available inArizona. Emissions were calc~~lated using several methods including mass balance, best engineering estimates,AP-42 emissions factors, CARB emissions factors, performance test results, permit applications, Mobile 6 model outputs from the Maricopa Association of Governments (MAG), vehicle traffic counts, Maricopa County emissions factors and the State of Arizona emissions factors. Emissions inventories from several individual facilities were developed by private consultants or in-house environmental personnel, using the above calculation methods, information gathered from site visits, and these were reviewed by GRIC's Compliance and Enforcement Manager (CEM). Since the Community experiences relatively slow growth when compared with the growth of communities like Metropolitan Phoenix, some of the emissiondata from the 1997 Elwas carried over to this 2007 El Update. For example, the levels of open burning and residential burning have remained relatively constant and many small stationary sources have also experienced little or no growth since 1997. Also, many of the small stationary sources do not keep accurate production data records because the facilitiesare below the pem~itting and reporting thresholds. The Gila River Tribal Council has recently approved anAir Quality Management Plan (AQMP), which allows for the implementation of an air quality regulatory program, permitting program, and a compliance inspection program. The Community's Air Quality Department is in the process of developing their first set of Non-Title V air quality permits for several industries located on the Community.

### 2 INTRODUCTION


### 2.1. Background The Gila River lndian Community (GRIC), afederally-recognized tribe, is a ruralcommunity located on approximately 374,000 acres in south- centralArizona, adjacentto thesouthern border of Phoenix, Chandler and Gilbert, with an on-reservation population of approximately 15,500 people (Figures 1 & 2). The reservationwas established in 1859 by Executive Order with Congressional approval. Members of the Gila River lndian Community are Akimel O'odham (Pima) and Pee Posh (Maricopa) and form the fourth most populous lndian Reservation in the United States. On the northern boundary, the Community is adjacentto the rapidly growing Phoenix metropolitan area. A portionof the Community (92,000 acres) lies within Maricopa County. This portionof the GRlC is located within the FederalNon-AttainmentArea for particulate matter lessthan 10microns (PMIO), which has been classified as "serious" by EPA (Figure 2). It is currently undeterminedto what extent air pollution from the Phoenix metropolitan area affects air quality within GRlC boundaries. The Community has three (3) industrial parks containing approximately50 industrial plants along with several industrial facilities located in out-lying areas. The Lone Butte Industrial Park, the largest of the three industrial parks, lies within the Maricopa County nonattainment area and includes one Federally-regulated major source (Pimalco). The remaining two industrial parks are much smaller and contain only minor sources of air pollution. Agricultural production throughout the Community has not changed significantly since 1997. There are currentlyapproximately35,000 acres inagricultural production throughout the Community. Approximately 6,700 agricultural acres are located within the Maricopa County non-attainment area. The largest source of air pollution within the Community isvehicle emissions. Interstate10 isthe single largest sourceof poll~~tion with approximately 1,400,000 vehicle miles traveled (VMT) daily. GRlC has approximately 160 miles of unpaved roads that are very rarely traveled and consis,tmainly of farm roads and roads accessing very remote areas. The Maricopa County PMI0 non-attainment area was designated in 1974 to include the urbanized portions of Maricopa County but also included the northern portion of GRlC (Figure 2). The boundarywas arbitrarily developed based on the Maricopa Association of Governments (MAG) operational area and did not includeany scientific informationfrom GRlC to support the non-attainment designation. GRlC was not allowed to comment during the designation process nor was scientific evidence from GRlC used to determine the boundaries of the nonattainment areas. No evidence has ever indicated that any portion of GRlC is in non-attainmentor even contributes to the non-attainment status within Maricopa County. GRlC plans to conduct additional monitoring in thefutureto supportthis position.The Community is facing several issues arising from the non-attainment status of the northern portion of the Community, includiug NSR and Title 5 permitting requirements for new industrial facilities planning to locate within the Community. The Gila River Tribal Council has recently approved anAir Quality Management Plan (AQMP), which allowsfor the implementation of an air quality regulatory program, permitting program, and a compliance inspection program. TheCommunity'sAir Quality Department is inthe process of developingtheir first set of Non-Title

### V air quality permits for several industries located on the Community. 

### 2.2. Study Area The Gila River IndianCommunity extends from the towns of Phoenix and Chandler onthe north, south to almost Casa Grande, to the Estrella Mountainson the west to Coolidgeon the east (Figure 2). The Gila River Indian Community lies in Sonoran Desert terrain ,thatis primarily light scrub and cactus with an elevation of approximately 1,200 to 1,400 feet above sea level. The temperaturevaries from approximately20°F in the winterto >I15°F in the summer. Annual precipitation is light with approximately 36 days per year with >0.01 inches. Wind speed and direction can vary, but generally the wind blows from the southwest to the northeast in the morning and reverses direction in the afternoon. Wind speed canvary from a slight breezeto 70 mile per hourwinds duringthe monsoon season.

### 3 METHODOLOGIES To update the 1997 El, the Gila River Department of Environmental Quality (DEQ) assessed both stationary and mobile source emissions. 

### 3.1. Point Sources For the purposes of this El, point sources are defined as stationary facilities (with point and/or area sources) within the boundaries of the Community. The pointsources listed in 1997 El were divided into the following five categories for this update: 1. Ongoing (since 1997); 2. Ongoing with changed names (since 1997); and 

### 3. New (operating in 2006 but not in 1997); 4. Discontinued (not operating in 2006); 5. Belowthe permitting and reporting thresholds. Emissions for the new point sources were developed using information supplied by the source or obtained during site visits pertaining to the type of processes employed, the types of materials/chemicals used, quantities of materials input to processes and type of pollution controlequipment operated. After collectingthis data, emissions were estimated usingAP-42 emissions factors, mass balance equations, source test information, and best engineering estimates. Several of the new sources were in operation for only a short period of time in 2007 or did not have readily available production data. Therefore,these sourceswere included under a category with facility elmissions belowthe permitting and reporting threshold. Emissions from these sources will be included in the next GRlC El, providedthe emissions from these facilities exceed the permitting and reporting threshold. The Community's Air Quality Department is in the process of developing their first set of Non-TitleV air quality permits for several industries located on the Community. This process will continue until all sources required to have a permit within the community are permitted. All permitted sources will be required to submit an annual El to the GRlC DEQ as a condition of their operatiqg permit. 

### 3.2. Area Sources Area source emissions include open burning emissions, agricultural emissionsfrom tillage and harvesting, and construction emissions. There has been little or no net change in the quantities of open burning and construction emissionssince 1997;therefore,the2007 area source emissions were assumed to be identical to 1997 area source emissions for thesesources. Agricultural-related emissions were adjusted for a slight increase inthe amount of land under agricultural production between 1997 and 2006. 

### 3.3. Mobile Sources EPA's Mobile 6 model was used to estimate emissions from onroad mobile sources (vehicle traffic). Emissionsof PMI0 from dirt roads and from paved roads were estimated using formulas provided inAP-42. Vehicle counts and road mileages were obtainedforthe most recent year available from the Arizona Department of Transportation (2006), GRlC Department of Transportation (2003, 2004), Maricopa County Department of Transportation (2005), and MAG (2005).4 

### SUMMARY 

### OF RESULTS Annual emissions estimates were developed for the five criteria pollutants 

### - PM10, CO, NOx, SOXandVOCs. A summary of the 2007 criteria pollutantemissions from each ofthe three sources categories is shown in Table 4.1. 

### TABLE 4.1 

### Summary of Source Emissions (tonslyr)

### 5 POINT SOURCES For the purpose of this inventory, point sources are defined as stationary facilities within the boundaries of the Community. The point sources from the 1997 Elwere divided into the following five categories for this update: 1. Ongoing (since 1997); 2. Ongoing with changed names (since 1997); and 

### 3. New (operating in 2006 but not in 1997); 4. Discontinued (operating in 1997 but not in 2006); 

### 5. Below the permitting and reporting thresholds. A summary of the emissions from the new and ongoing pointsources is presentedinTable 5.1 below. 

### TABLE 5.1 Point Source Emissions (tonslyr)

"-" = zero value or not applicable 

### 5.1. Ongoing Sources Source New Sources Ongoing Sources TOTAL

Ongoing point sources on the Community are those sources that were operating in 1997 and 2006. Several ongoing facilities also underwent a name change since 1997. NOx 0.79 174.10 174.89

Available errrissions data is limited for these ongoing sources because mostofthe sources do not currently have an air quality permit. Also, most of these sources have not changed significantly since 1997. Therefore, with the exception of two facilities (Rinker's Maricopa and Santan plants),the 1997 El emissions data was used for the 2007 El Update. PMIO

888.63 159.06 1,047.69

A summary of the ongoing sources (without a name change) and their associated emissions is presented in Table 5.2. VOC 0.06 141.58 141.64 CO

0.17 161.05 161.22 SOX 1.35 29.28 30.63TABLE 5.2 ongoing1Point Source Emissions (tonslyr) 

### ( Arizona Box 

### - 0.17 

## 1 - 

### I BMC West 

### I 0.2

### 1 

### - I - 

### I - 

### I - 

### I SOX Source Alexco 

# I Bondurant 19 

## 1 4 

### ( 2.57

## 1 P&o 0.02

Casa Blanca MKT Classy Closets DBCl



### I KT Fabrication 

### I - 

### I - 

### I - 

### I - 

### I - 

### I CO 

## I NOx

0.05 

### 1 0.24

Fertizona San Tan Firebird Raceway Gila River Farms Gin Gila River Gas Station Komate gas station (53Ave & Pecos Rd) 

### I Pacific Scientific 

### I - 

### I 

### - I - 

### 1 0.03 

### 1 - 

### I VOC 2

0.3 0.67

6.7

A summary of the ongoing sources with a name change, their former name, and their associated emissions is presented in Table 

### 5.3. -

Pimalco Pima Valve Rock Solid Romic Therm-0-Rock West Triangle Truss Wilbur Ellis TOTAL

TABLE 5.3 Ongoing Changed ~ame' Point Source Emissions (tonslyr) 1.7

- - 

### -

"-" = zero value or not applicable

= Operating in 1997 and 2006 6.86 9.5 48.7

0.4 73.35 13

Source 

## 1 1997 Name 

## 1 PMto 

## I CO 

## I NOx 

### [ VOC 

## I

= Sources with a namechange between 1997 and 2006 3.1

30.95

- 1.8

53.5

Animal Nutrition 

### 1 Dairv Nutrition Honeywell Kaiser Aluminum MTD Rinker (Maricopa plant) Rinker (San Tan plant) Monsanto Triumph Thermal Processing Waste Management Inc. -

- 0.22 - 0.75

10 5.1 -

-

17.72

7.4

42.36

2 

### 1 Allied Signal Plymouth Tube Ryobi United Metro#41 United Metro#48 Stoneville Seed AMTI Sanifil -

TOTAL 66.29 0.28 - 3.3 0.2 0.1



### - 94.11

2.8 0.11 0.024 22.45 22.73 34

- 1.6 0.09 -

0.03

0.1 2

"-" = zero value or not a~~llcable 85.71 11.3 0.19

8.4 35.83 51.68 0.1 0.05 107.55 3.6 0.93 0.006 28.27 98.27 0.4 0.26 131.74 8 9.9

3 8.73 16.64 1.2 3.2 0.003 14.75 11.18

0.03 47.47 29.16Rinker submitted Non-TitleV permit applicationsfor their two facilities (Maricopa and San Tan plants) to satisfy the requirements of GRIC's Non-Title V permitting process. The information and emission data supplied intheir permitapplications was usedfor this 2007 El update. 

### 5.2. New Sources New point sources on the Community are those sources that were not operating in 1997 butwere operating in 2006. A summary of the new sources and their associated emissions is presented in Table 5.4. TABLE 5.4 ~ew' Point Source Emissions (tonslyr)

Gila River Sand & Gravel - Santan 441.8 

### 1 0.04 

### 1 0.21 

### 1 0.02 

### 1 0.01 

# 1 Champion Homes Redman Homes Gila River Sand & Gravel - Maricopa NOx CO Source Cemex - 429.89 Hanson Love's Travel Center PMlo 12.4

Maricopa Ready Mix

Five of the new sources listed inTable 5.4submitted productiondata andlor emission data to satisfy the requirements of GRIC's permitting process. Additional information was collected by the CEM while conducting on-site visits and various methodologies were appliedto derivethe estimated emissions. The remainingfive sourceswere only operating for a short period of time toward the end of 2007 or have limited production or emission factor data available. Emissions from these five sources were not included in this update because GRlC is using data generated between 1997 and 2006 for the 2007 updated Emission Inventory. VOC

0.04 3.5 1.04 

## 1 Superlite Block Triumph Engines Triumph Precision Castings TOTAL

Emissions from the point sources were calculated using mass balance, material usage estimates and AP-42 emission factors. Several of the above-listed sources hired consultants or used in-house environmental personnel to develop their individual permit application with emission estimates. The permit applications were reviewed by the GRlC CEM for reasonableness, completeness and correct emission factors before includingthe emissions data in the permit applications into the 2007 El. Emission estimates for other sources were prepared by GRlC consultants using the information supplied inthe permit applications. SOX

0.21 0.09

"-" = zero value or not applicable 

### ' = Operating in 2006, but not in 1997 888.63 - 0.02 0.37 -

0.17 0.01 0.02

-

0.79 1.33

0.06 1.355.3. DiscontinuedSources A list of the discontinued sources and their associated emissions is presented inTable 5.5. TABLE 

### 5.5 ~iscontinued' Point Source Emissions (tonslyr) 

# I PY,. 

# 1 CO 

# I NOx 

# 1 WH: 

# 1 SOX 

# I Arizona Processing 35 

# 1 0.16

# 1 0.94

# 1 0.01 

## / - Fertizona Coolidge Image of Wicker Philli~s Services

5.4. Facilities Below PermittingAnd Reporting 'Thresholds Solkatronic 1Air Products TOTAL

Several facilities are below the permitting thresholds or have equipment that is exempt from permitting. The permitting thresholds are identified intheAQMP and include, but are not limited to, facilities that emit one ton per year or less of any single regulated air pollutant; 1,000 pounds peryear or less of any singe HAP or oneton of any combination of HAPs; or 300 pounds per year or less of any single ultra-HAP or combination of ultraHAPs. These facilities are listed in Table 5.6. 0.76 - 5.5

TABLE 5.6 Facilities Below Permitting And Reporting ~hresholds' I I I "-" = zero value or not applicable 

### ' = Operating in 1997 but not in 2006 41.26 - -



# I Allison LLC (subleaseto Lumber Products) 

### I Iron Citv Rentals 0.16

Source A & A Precast 0.15

Source Gila River Utility Authority 

# I ADESA 

### I McNeil Brothers 

### -

- 

## I
0.94

Access Recovery Acker Stone Lone Butte Trade Center Lumber Products



### I Factorv EXDO Home Center 

### I Robert Ewina General Contractor 

### I 0.32 0.48

Beaudry RV Environmental Stoneworks 

### -

Monty Brother's Landscaping Peterson Transportation


# 1 Gila River Telecomm

1 = Oneton per year or less of any single regulated air pollutant; 1,000pounds per year or less of any singe HAP or one ton of any combination of HAPs;or 300 pounds per year or less of any single ultra-HAP or combination of ultra-HAPS. Ferrell Gas Fillmore Partnership Freightliner Sterling Western Star of Arizona Rock N Roll Trucking San Carlos Irrigation Project Verizon Wireless

### 6 

### AREA SOURCES For the purposeof this El update, area emission sources include open burning,agricultural tillage and harvesting, residential fuel combustion, agricultural wind blown dust (nonanthropogenic) and agricultural nitrogen fertilizer usage (non-anthropogenic). Emissions from wildfires have not been calculated since wildfires rarely occur in the GRlC Sonoran Desert environment. Except for agricultural-related sources (e.g., tilling, harvesting, windblown dust, and fertilizer usage), the area sources have not changed significantly since 1997. Therefore, for non-agricultural sources, the 1997 Elemissions datawas used forthis2007 El Update. For agricultural sources, the 1997 El indicates that 32,196 acres were in agricultural production. In 2006, the most recent year with available data,there were 35,065 acres in production (see Figure 3, attached). For both El timeframes (1997 and 2006), the major crops produced on the Gila River IndianCommunity includedalfalfa, cotton,wheatlbarley, citrus, and vegetables. These crop types were used to estimate the emissions for the agricultural sources in both the 1997 and 2007 Els. Therefore, the 8.9% increase in agricultural production from 1997to 2006 was applied to the 1997 emissions for tilling & harvesting (448.11 tpy PMlo), windblown dust (241 tpy PMlo), and fertilizer usage (45tpy NOx) to estimate the emissions for this El. A summary of the area source emissions for the 2007 El is presented in Table 6.1 below. 

### TABLE 6.1 

### Area Source Emissions (tonslyr)

"-" = zero value or not applicable Source Open Burning Agricultural Tilling & Harvesting Residential Fuel (gas) Combustion Residential Wood Combustion AgriculturalWindblown Dust Nitrogen Fertilizer Usage TOTAL PMIo 0.12 487.99

0.027 8.4 262.45
758.99 CO 1.2



### - 0.33 61.4



### - 62.93 NOx

-
1 97

0.6

- 49 51.57 VOC

0.026

55.9
- 

### - 55.93 SOX

0.002 0.1

-
- 0.107 MOBILE SOURCES Mobile emission sources include nonroad vehicles and onroad vehicles. 7.1. Nonroad Emissions from nonroad mobile sources result from combustion of fuels from mobile equipment other than onroad motor vehicles. These sources include recreational vehicles, construction equipment, lawn and garden equipment,farm equipment, marine vessels and locomotives. The majority of sources listed in this category will not be addressed in this section due to the lack of these activities within the boundaries of the Comniunity. Emissions from marine vessels, recreational vehicles, lawn and garden equipment and construction activities are not addressed inthis inventory due to the lack of these activities during the 2006 calendar year. Emissions from locomotives are considered insignificant since only small rail sidings are present within the Community and rail traffic is almost nonexistent. Emissions .fromfarm equipment are the only significant source of nonroad emissions within the Community. The ratio of 2006 to 1997 agricultural acreage was used to adjust the 1997 

### Eldata for the 2007 El Update (i.e. an increaseof 8.9%). The nonroademissions for the 2007 El Update is presented in Table 7.1 below. TABLE 7.1 Nonroad Mobile Source Emissions (tonslyr)

"-" = zero value or not applicable Saurce Agricultural Tractor Operation
7.2. Onroad This section explains the development of onroad motor vehicle emissions estimates from vehicle trafficwithin the boundariesof GRIC. Vehicle traffic throughthe Community byfar represents the most predominant source of air pollution within the Community. The majority of the vehicle traffic can be attributed to Interstate 10 running between Phoenix and Tucson bisectingthe GRIC. PMdo GO 22 NOx 28 VOC 5 SOXA summary of the onroad emissions for the 2007 El Update is presented in Table 7.2. 

### TABLE 7.2 Onroad Mobile Source Emissions (tonslyr)

"-" = zero value or not applicable 

### 7.2.I. 

### Data Collection Vehicle counts for roads maintained by the State of Arizona were supplied by theArizona Department of Transportation (ADOT). MAG supplied a map listing vehicle counts over stretches of road maintained by the Maricopa County Department of Transportation (MCDOT). The GRlC DepartmentofTransportationsupplied informationdocumentingthe total mileage of paved and dirtlgravel roads within the Community. A portion of these roads are maintained bythe Bureauof IndianAffairs and vehicle counts are not available. The total mileage of roads maintained by the State and County was subtracted from the total roadswithin the Communityto revealthose roads without vehicle counts. Estimates of daily vehicle traffic were made for the portion of roads without vehicle counts. Daily Vehicle Miles Traveled (VMT) were calculated by multiplyingthe numbers of vehicles per day (vpd) by mileage information supplied bythe State, County and GRIC. A summary of the daily VMT for the five major road types is presented in Table 7.3 below. VOC 923.6

923.6 

### Source Vehicle Emissions Paved Road Dust Unpaved Road Dust TOTAL



### TABLE 

### 7.3 Onroad Mobile Source VMT SOX 36.9

36.9 CO 10,566.3
- 10,566.3 

### who

50.9 332.9 2.2 386.0

VMT = Vehicle Miles Traveled per day NOx 2,027.0

2,027.0

Emission factors were obtained from EPA's Mobile 6 model. MAGsupplied GRlCwiththe 2005 Mobile 6.2.03 input and output files usedto calculate emissions factors for their 2006 El. One set of output emissions factors included credit for implementation of the Area A (roughly Maricopa County) IM-240 vehicle emissionstesting program. These factorswere applied to the daily VMT within Maricopa County. Another set of emissions factors wasgenerated for vehicles not required to pass the Maricopa County errrissions testing program (IM-240) and these factors were applied to the daily VMT within Pinal County. 7.2.2. Calculation Methods Criteria pollutant emissions for each vehicle classification traveling within each road type were calculated according to the following equation:


### Ex= 

### EFxx VMT, x VCPx 365 days 

# [ yr )x(45!6g)x[2E:lb) Where: Ex 

### = Criteria pollutantX emissions (i.e., PM10, CO, etc.) for a specific vehicle class EFx 

### = Emission factor for criteria pollutant X from Mobile 6 VMT 

### = Dailyvehicle miles traveled for road type 

### Y (i.e., urban interstate, etc.) VCP = Vehicle class percentage of total vehicles The resulting emissions for each vehicle classification were totaled to generate the total PMlo, CO, NOx, VOC and SOXemissions for each road type. PMIO emissions from road dust generated by vehicle trafic on paved roads were calculated using the equation for paved roads listed in AP-42 Section 13.2.1 (Equation 1) and silt loading values from Maricopa County's 2005 El. Daily VMT were broken down to three categories with three different silt loading (sL) values: Interstates (sL 

### = 0.02 glm2); Roads with <5,000 VMTIday (sL = 0.067 g/m2);and Roads with >5,000 VMTIday (sL 

### = 0.23 g/m2). The AP-42 equation for vehicles traveling on paved public roads is:

Where: EF 

### = Particulate emissions factor (IbsNMT) k = Particle size multiplier for particulate size range of interest (0.016 lbNMTfor PM10,AP-42 Table 13.2.1-1) sL = Road surface siftloading (g/m2.Maricopa County 2005 El) W = Weight of vehicle (3 tons, Maricopa County 2005 El) C = Emission factor for 1980's vehicle exhaust, break & tire wear (0.00047 IbNMT, AP-42 Table 13.2.1-2)PMIO emissions from road dust generated by vehicle traffic on unpaved roads were calculated usingthe equation for unpaved roads listed inAP-42 Section 13.2.2 (Equations I b and 2), a silt loading value from Maricopa County's 2005 El, and daily VMT generated using best available engineering estimates. Sincevehicle traffic on unpaved roads isvery limited within the Community, it was assumedthat two vehicles per day traveled on each unpavedsegment. The rural portion of the Community has remained relatively unchanged since 1997;therefore, the length of unpaved roads from the 1997 Elwas used forthe 2007 El Update (162.8 miles). The AP-42 equationfor vehicles traveling on unpaved public roads is:

Where: EF 

### = Emission factor (IbsNMT) k 

### = Particle size multiplier (1.8 for PM10, AP-42 Table 13.2.2-2) s = Silt content of road surface (11.9%, Maricopa County 2005 El) S = Mean vehicle speed (25 mph, Maricopa County 2005 El) M 

### = Surface material moisture content (0.5%, Maricopa County 2005 El) C 

### = Emissionfactor for 1980'svehicle exhaust, break

### &tirewear (0.00047 IbNMT,AP-42 Table 13.2.2-4) p 

### = #of dayslyrwith rainfallof at least 0.01 in. (31days, Western Regional Climate Center, Sacaton,AZ) a 

### = for PMIO (1, AP-42 Table 13.2.2-4) c 

### = for PMlO (0.2, AP-42 Table 13.2.2-4) d 

### = for PMIO (0.5, AP-42 Table 13.2.2-4)8 

### REFERENCES Arizona DepartmentofTransportationWebsite. Vehicle Counts for Arizona Roads2003

### - 2006. Compilation of Air Pollution Emissions Factors AP-42, Fifth Edition, Volume I Gila River lndian Community. 1997 Emissions lnventory for the Gila River lndian Community, dated October 1998. Gila River lndian Community Department of Transportation. List of Unpaved 

### 1 Paved Roads by District 

### -for Air Quality Program (memorandum dated March 4, 2005). Gila River lndian Community Department of Transportation. Traffic Count Data (memorandum dated April 7, 2004). Maricopa Association of Governments. Mobile 6 input and output files for 2005. Maricopa County Air Quality Department. 2005 Periodic Emissions lnventory for PM10for the Maricopa County, Arizona, Nonattainment Area, dated May 2007. Maricopa County Departmentof TransportationWebsite. Traffic Counts for 1999

### -2005.FIGURES

### Figure 2. 

### Map of Gila River indian Community, Maricopa 

### & Pinal Counties, 

### & PMIO Non-Attainment Area Lenend Gila River Indian Community PM10 Non-Attainment Area 

# 0 Pinal County 

# n Maricopa County

N 04.59 18 27 36 

# -
~iles 1 inch equals 20 miles