Air Quality General Conformity Evaluation 

April 11, 2012 

Bureau of Land Management 

Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and 

Environmental Impact Statement 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation i 

TABLE OF CONTENTS

Section Page 

1. Introduction ....................................................................................................................... 1

2. The General Conformity Process .................................................................................... 3

2.1. Overview ............................................................................................................................................... 3

2.2. Applicability ........................................................................................................................................... 6

2.2.1. Direct and Indirect Emissions ............................................................................................ 6

2.2.2. Exemptions and Actions Presumed to Conform .......................................................... 7

2.3. Evaluation and Analysis Thresholds ................................................................................................. 7

2.4. Conformity Determination ............................................................................................................... 7

3. Evaluation of Emissions for the Proposed RMP ............................................................. 8

3.1. Approach to the Analysis ................................................................................................................... 8

3.2. Identification of Emissions Changes by Decision Area ............................................................. 10

3.2.1. Lower Sonoran Decision Area ........................................................................................ 10

3.2.2. Sonoran Desert National Monument Decision Area ................................................ 25

4. Results of the Analysis .................................................................................................... 34

5. Conclusion ........................................................................................................................ 35

6. References ........................................................................................................................ 36

TABLES

Table 1. State Implementation Plans Applicable to the Planning Area ........................................................... 3

Table 2. General Conformity Emissions Thresholds Applicable to Planning Area ...................................... 4

Table 3. Summary of Emission Changes by Resource Program ..................................................................... 10

Table 4. Key Lands and Realty Allocations for the Lower Sonoran Decision Area ................................. 11

Table 5. Key Land Use Allocations for Livestock Grazing for the Lower Sonoran Decision 

Area .............................................................................................................................................................. 12

Table 6. Key Land Use Allocations for Minerals Management in the Planning Area ................................ 14

Table 7. Key Land Use Allocations for Recreation Management for the Lower Sonoran 

Decision Area ............................................................................................................................................ 17

Table 8. Estimated Construction Emissions (tons) for Site and Road Development in the 

Buckeye Hills East RMZ ........................................................................................................................... 19

Table 9. Key Land Use Allocations for Special Designations in the Lower Sonoran Decision 

Area: ACECs ............................................................................................................................................. 20

Table 10. Key Travel Management Allocations for the Lower Sonoran Decision Area ............................ 21

Table 11. Estimated Emissions (tons per year) due to Increased Visitation and OHV Races in the 

Buckeye Hills East RMZ ........................................................................................................................... 23

Table 12. Land Use Allocations for Visual Resources Management for the Lower Sonoran 

Decision Area ............................................................................................................................................ 24

Table 13. Key Land Use Allocations for Wildlife Habitat for the Lower Sonoran Decision Area .......... 25

Table 14. Key Lands and Realty Allocations for the SDNM ............................................................................. 26

Table 15. Key Land Use Allocations for Livestock Grazing for the SDNM .................................................. 27
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Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation ii 

Table 16. Key Land Use Allocations for Recreation Management for the SDNM ...................................... 28

Table 17. Estimated Construction Emissions (tons) for Site and Road Development in the Anza 

NHT Corridor ........................................................................................................................................... 30

Table 18. Key Land Use Allocations for Special Designations in the SDNM: ACECs ............................... 31

Table 19. Key Travel Management Allocations for the SDNM ........................................................................ 31

Table 20. Estimated Recurring Emissions (tons per year) due to Increased Visitation and Road 

Maintenance in the Anza NHT RMZ .................................................................................................... 32

Table 21. Land Use Allocations for Visual Resources Management for the SDNM .................................... 33

Table 22. Key Land Use Allocations for Wildlife Habitat for the SDNM ...................................................... 34

Table 23. Summary of Net Emissions for Conformity Evaluation ................................................................... 34

MAPS

Map 1. Air Pollutant Nonattainment Areas ........................................................................................................ 2

Map 2. Primary Geographical Reference Areas ................................................................................................. 5

Map 3. Alternative E Recreation Management ................................................................................................. 16
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April 2012 Air Quality General Conformity Evaluation iii 

ACRONYMS AND ABBREVIATIONS

ACEC Area of Critical Environmental Concern 

AUM animal unit month 

BLM Bureau of Land Management 

CAA Clean Air Act 

CFR Code of Federal Regulations 

CO carbon monoxide 

EIS Environmental Impact Statement 

EPA U.S. Environmental Protection Agency 

ERMA Extensive Recreation Management Area 

LSDA Lower Sonoran Decision Area 

LUA land use authorization 

NAA nonattainment area 

NAAQS National Ambient Air Quality Standards 

NHT National Historic Trail 

NO2 nitrogen dioxide 

NOx nitrogen oxides 

OHV off-highway vehicle 

PM particulate matter 

RMA Recreation Management Area 

RMP Resource Management Plan 

RMZ Recreation Management Zone 

ROW right-of-way 

SDNM Sonoran Desert National Monument 

SIP State Implementation Plan 

SO2 sulfur dioxide 

SRMA Special Recreation Management Area 

UL Undesignated Land 

U.S.C. United States Code 

VOC volatile organic compound 

VRM Visual Resource Management 
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April 2012 Air Quality General Conformity Evaluation 1 

1. INTRODUCTION

This report describes the evaluation of actions and activities proposed under the Bureau of Land 

Management (BLM) Lower Sonoran and Sonoran Desert National Monument (SDNM) Proposed 

Resource Management Plan (RMP) and Final Environmental Impact Statement (EIS) revision project for 

conformance with the applicable air quality plans. The Lower Sonoran and SDNM RMP, when 

approved, will provide management direction for the lands managed by the BLM Lower Sonoran Field 

Office in south central Arizona. These lands are referred to as the Planning Area in this document. The 

Planning Area is divided into two Decision Areas: the SDNM Decision Area, which includes all public 

lands in the SDNM, and the Lower Sonoran Decision Area (LSDA), which includes all public lands within 

the Planning Area outside the SDNM. This report describes air pollutant emission estimates for both 

Decision Areas for the Proposed RMP (Alternative E). 

To reduce air pollution levels, the Federal Government and state agencies passed legislation and 

established regulatory programs to control sources of pollutant emissions. The Clean Air Act (CAA) 

(42 United States Code [U.S.C.] §7401 et seq.) is the primary Federal legislation that addresses air 

quality. Under the authority of the CAA and its amendments, the U.S. Environmental Protection Agency 

(EPA) established National Ambient Air Quality Standards (NAAQS) (40 Code of Federal Regulations 

[CFR] 50) for six relatively common air pollutants – known as “criteria” pollutants because EPA 

regulates them by developing human-health-based or environmentally-based criteria for setting 

permissible concentrations. The criteria pollutants are carbon monoxide (CO), lead, nitrogen dioxide 

(NO2), ozone, particulate matter (PM) with an aerodynamic diameter equal to or less than 10 microns 

(PM10, or coarse particles) and 2.5 microns (PM2.5, or fine particles), and sulfur dioxide (SO2). Ozone is 

not emitted directly, but is formed from emissions of the ozone precursor pollutants nitrogen oxides 

(NOx) and volatile organic compounds (VOCs). For further information on the criteria pollutants and 

sources of emissions, see the Air Quality section in Chapter 3 of the Lower Sonoran and SDNM 

Proposed RMP and EIS. 

Under the CAA, EPA designates geographic areas as “attainment” if pollutant concentrations are within 

the NAAQS, “nonattainment” if pollutant concentrations exceed the NAAQS or “unclassifiable” if 

available monitoring data are insufficient to assign an attainment status. Former nonattainment areas 

that have achieved compliance with the NAAQS are designated as “maintenance” areas. Each state with 

a nonattainment area is required to develop and implement a State Implementation Plan (SIP) 

documenting how the area will reach attainment within periods specified in the CAA. For maintenance 

areas, the SIP must document how the state intends to maintain compliance with the NAAQS. When 

EPA changes an NAAQS, each state must revise its SIP to address how it plans to attain the new 

standard. 

EPA designated portions of the Planning Area as nonattainment for ozone (Phoenix/Mesa area), 

moderate nonattainment for PM10 (Ajo and Miami areas), serious nonattainment for PM10 (Phoenix 

area), nonattainment for PM2.5 (West Central Pinal County, i.e., Maricopa/Stanfield/ Casa Grande area), 

maintenance for CO (Phoenix area), and maintenance for SO2 (Ajo and Miami areas). Map 1 

(reproduced from RMP Map 3-1) displays these areas. 
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Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Map 1. Air Pollutant Nonattainment Areas 

Note: Reproduced from RMP Map 3-1. 
Lower Sonoran and Sonoran Desert National Monument 

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April 2012 Air Quality General Conformity Evaluation 3 

Table 1 identifies the SIPs applicable to the Planning Area. 

Table 1. State Implementation Plans Applicable to the Planning Area 

Pollutant State Implementation Plan 

CO Carbon Monoxide Redesignation Request and Maintenance Plan for the Maricopa County 

Nonattainment Area (MAG 2003) 

Ozone Eight-Hour Ozone Plan for the Maricopa County Non-attainment Area (MAG 2007a) 

PM10 MAG 2007 Five Percent Plan for PM10 for the Maricopa County Non-attainment Area 

(MAG 2007b) 

Ajo PM10 Limited Maintenance Plan and Request for Redesignation (ADEQ 2011) 

Miami Moderate Area PM10 Limited Maintenance Plan and Request for Redesignation to 

Attainment (ADEQ 2008) 

PM2.5 West Central Pinal County State Implementation Plan (PAQCD, in preparation) 

SO2 Ajo Sulfur Dioxide Nonattainment Area State Implementation and Maintenance Plan 

(ADEQ 2002a) 

Miami Sulfur Dioxide State Implementation and Maintenance Plan (ADEQ 2002b) 

CO carbon monoxide 

PM particulate matter 

SO2 sulfur dioxide 

2. THE GENERAL CONFORMITY PROCESS

2.1. OVERVIEW

Section 176(c) of the CAA states that no Federal entity shall engage in, support in any way or provide 

financial assistance for, license or permit, or approve, any activity which does not “conform” to the 

applicable SIP. The purpose of this conformity requirement, as stated in Section 176(c), is to ensure that 

Federal activities: (1) comply with the applicable SIP’s purpose of eliminating or reducing the severity 

and number of violations of the NAAQS, and achieving expeditious attainment of such standards; and (2) 

assuring that such activities will not: (a) cause or contribute to any new violation of any standard in any 

area; (b) increase the frequency or severity of any existing violation of any standard in any area; or (c) 

delay timely attainment of any standard or any required interim emission reductions or other milestones 

in any area. 

To implement Section 176(c), the EPA has issued two regulations: (1) the Transportation Conformity 

Rule (40 CFR part 93, subpart A) which applies to Federal actions funded under the Federal Aid 

Highway Act (U.S.C. Title 23) or the Federal Transit Act (U.S.C. Title 49 Chapter 53), and (2) the 

General Conformity Rule (40 CFR Part 93, Subpart B) which applies to all other Federal actions. Most 

actions subject to the Transportation Conformity Rule are highway or transit projects funded by the 

Federal Highway Administration or the Federal Transit Administration. BLM actions are not funded by 

these agencies and not subject to the Transportation Conformity Rule, but are subject to the General 

Conformity Rule. The conformity rules apply only to Federal actions in nonattainment or maintenance 

areas (collectively referred to as nonattainment areas [NAAs]). 

The General Conformity Rule established a process based on emissions analysis to determine whether a 

Federal action conforms to the applicable SIP. When developing the General Conformity Rule, the EPA 
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April 2012 Air Quality General Conformity Evaluation 4 

recognized that many actions conducted by Federal agencies do not result in substantial increases in air 

pollutant emissions in nonattainment and maintenance areas. Therefore, the EPA established threshold 

levels (also referred to as de minimis levels) for emissions of each of the criteria pollutants. Table 2 lists 

the criteria pollutant thresholds that are applicable to the Planning Area. Map 2 (reproduced from RMP 

Map 1-2) displays the locations of the Planning Area and the Decision Areas in the region along with 

other geographic references that are useful in locating places named in the RMP and the conformity 

analysis. 

Table 2. General Conformity Emissions Thresholds Applicable to Planning Area 

City or Region Pollutant Area Designation Threshold 

(tons per year) 

Ajo PM10 Moderate Nonattainment 100 

Ajo SO2 Maintenance 100 

Miami PM10 Moderate Nonattainment 100 

Miami SO2 Maintenance 100 

Phoenix CO Maintenance 100 

Phoenix PM10 Serious Nonattainment 70 

Phoenix/Mesa Ozone Nonattainment (former Subpart 1) 100 (NOx or VOC) 

West Central Pinal County PM2.5 Nonattainment 100 

Sources: Area Designation – 40 CFR 81, Threshold – 40 CFR § 93.153(b)(1) and (2). 

CO carbon monoxide 

NOx nitrogen oxides 

PM particulate matter 

SO2 sulfur dioxide 

VOC volatile organic compound 
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Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Map 2. Primary Geographical Reference Areas 

Note: Reproduced from RMP Map 1-2. 
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April 2012 Air Quality General Conformity Evaluation 6 

If the net emissions increases attributable to the Federal action are less than the threshold levels, then 

the action is presumed to conform and no further conformity evaluation is required. If the emissions 

increases exceed any of the thresholds, and the action does not meet any of a number of criteria in the 

rule for exemptions or presumption of conformity, then a formal conformity determination is required. 

A conformity determination can include air quality modeling studies; consultation with EPA and state air 

quality agencies; and commitments to revise the SIP, obtain emission offsets, or to implement measures 

to mitigate air quality impacts. 

The conformity process is conducted in three phases: applicability, evaluation, and determination. The 

applicability phase determines whether the Federal action is exempt from the conformity rule or 

otherwise does not require further analysis to demonstrate conformity. Actions that require further 

analysis to demonstrate conformity proceed to the evaluation phase. The evaluation phase requires 

estimating the changes in emissions due to the action (i.e., the proposed Federal action emission levels 

minus the no action emission levels, also known as the “net emissions”) and comparing them to the de 

minimis thresholds. If the changes in emissions due to the action would exceed the thresholds, then the 

determination phase applies, in which a formal conformity determination must be prepared. 

2.2. APPLICABILITY

The first phase of the conformity process evaluates whether the conformity regulations would apply to 

the action. A conformity determination is not required if any of the following conditions apply: 

1. The Federal action would occur in an attainment area; 

2. The emissions caused by the action are not direct or indirect emissions as defined in the 

General Conformity Rule; 

3. The action is listed in the rule as exempt; 

4. The action is listed in the rule or by BLM as presumed to conform; or 

5. The emissions increases due to the action are less than the de minimis levels. 

In addition, a conformity determination is not required for alternatives other than the proposed Federal 

action. Consequently, the conformity analysis of the RMP was conducted only for the Proposed RMP 

(Alternative E). 

2.2.1. DIRECT AND INDIRECT EMISSIONS

With respect to the second condition above, the General Conformity Rule defines emissions as direct 

or indirect (40 CFR § 93.152). Emissions that do not meet the definitions of direct or indirect are 

exempt from the General Conformity Rule. Direct emissions are those that occur at the same time and 

place as the Federal action. As stated in 40 CFR § 93.152, indirect emissions are those emissions of a 

criteria pollutant or its precursors that meet the following definition: 

1. That are caused or initiated by the Federal action and originate in the same nonattainment or 

maintenance area but occur at a different time or place from the action; 

2. That are reasonably foreseeable; 

3. That the agency can practically control; and 

4. For which the agency has continuing program responsibility. 

For the conformity evaluation, BLM used this four-point definition of emissions to identify actions that 

could increase emissions. 
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April 2012 Air Quality General Conformity Evaluation 7 

2.2.2. EXEMPTIONS AND ACTIONS PRESUMED TO CONFORM

Certain Federal actions are exempt from the requirements of the General Conformity Rule or are 

presumed to conform because they result in no emissions or minimal emissions. Common examples of 

these actions include continuing and recurring activities such as permit renewals where activities 

conducted will be similar in scope and operation to activities currently being conducted; routine 

operation of facilities, mobile assets, and equipment; and transfers of ownership, interests, and titles in 

land, facilities, and real and personal properties. (See 40 CFR § 93.153[c] and [d] for the complete list of 

actions.) BLM accounted for exemptions, which cover many management actions, in identifying actions 

that could increase emissions for purposes of the conformity evaluation. 

The General Conformity Rule contains a provision that allows agencies to develop their own list of 

actions presumed to conform which would be exempt from the requirements of the rule. BLM has not 

established a list of actions presumed to conform under its air quality guidance (Manual 7300 – Air 

Resource Management Program). 

If the Federal action would occur in a nonattainment or maintenance area, would have direct or indirect 

emissions, and is not on the list of actions that are exempt or the list of actions presumed to conform, 

the emissions resulting from the Federal action must be analyzed and the results compared to the de 

minimis levels. 

2.3. EVALUATION AND ANALYSIS THRESHOLDS

In the second phase of the conformity process, the total annual emissions of the pollutant(s) of concern 

resulting from the Proposed RMP are estimated, and any increases are compared to the No Action 

Alternative. Numerous modeling and calculation methodologies are available to estimate emissions 

depending on the characteristics of the source and the planned activities. The increase compared to the 

No Action Alternative (the net emissions) is compared to the de minimis thresholds that apply to the 

nonattainment or maintenance area in which the action would occur. If the estimated net emissions are 

less than the applicable de minimis thresholds, the conformity determination requirements do not apply 

to the Federal action. 

2.4. CONFORMITY DETERMINATION

If the estimated net emissions are greater than the applicable de minimis thresholds, the Federal agency 

must prepare a conformity determination for the Federal action. The General Conformity Rule 

provides eight basic approaches or criteria for demonstrating conformity: 

1. Document that the emissions from the action are specifically identified and accounted for in the 

implementation plan (see 40 CFR § 93.158(a)). 

2. Obtain a statement from the applicable state, tribal, or local air quality agency that the emissions 

from the action along with all other emissions in the area do not exceed the budget for those 

emissions in the implementation plan (see 40 CFR § 93.158(a)). 

3. Have the state or tribe agree to revise the implementation plan to include the emissions from 

the Federal action (see 40 CFR § 93.158(a)). 

4. Have the local Metropolitan Planning Organization provide a statement that the emissions are 

included in the modeling for a conforming transportation plan and program (see 40 CFR § 

93.158(a)). 

5. Conduct air quality modeling to demonstrate that the emissions will not cause or contribute to 

a violation of the NAAQS (see 40 CFR § 93.158(a)). This modeling option is allowed for 

demonstrating conformity of directly-emitted pollutants only. (EPA does not believe that 
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April 2012 Air Quality General Conformity Evaluation 8 

current models are adequate to reasonably predict the project-level impact of individual sources 

of precursors of ozone or PM2.5. See the preamble to the 2010 conformity rule amendments, 

75 Federal Register 17254.) 

6. Fully mitigate or offset the increase in emissions (see 40 CFR § 93.158(a) and § 93.160). 

7. Develop and implement a facility-wide emission budget. This approach requires a revision to 

the implementation plan as in approach 4 above. If the net emissions from the Federal action 

along with the other emissions from the facility do not exceed the budget, then the Federal 

action is presumed to conform (see 40 CFR § 93.161). 

8. Create and apply emission reduction credits. Credits must meet several requirements in order 

to be eligible for use in a conformity determination (see 40 CFR § 93.165). 

The conformity analysis procedures in the General Conformity Rule contain detailed technical 

requirements for demonstrating how an action would conform to the applicable implementation plan 

under these approaches (see 40 CFR § 93.159). 

If a conformity determination were to be required for the RMP, BLM would select one or more of these 

options to develop a formal conformity determination for the Proposed RMP. 

3. EVALUATION OF EMISSIONS FOR THE PROPOSED RMP 

3.1. APPROACH TO THE ANALYSIS

This air quality general conformity analysis determines whether or not the activities and actions of the 

Proposed RMP are subject to and meet the requirements of the General Conformity Rule and conform 

to the applicable SIPs. This conformity evaluation discusses the proposed management actions within 

each program area and identifies whether the Proposed RMP potentially could result in an increase in 

criteria pollutant emissions compared to the No Action Alternative. For those actions that would result 

in a potential increase in emissions, BLM quantified the increase. 

BLM first reviewed SIPs and other relevant documents issued by EPA, the Arizona Department of 

Environmental Quality, the Maricopa Association of Governments, The Maricopa County Air Quality 

Department, the Pima County Department of Air Quality, and the Pinal County Department of Air 

Quality for any provisions that would affect the General Conformity requirements applicable to the 

Proposed RMP. 

Based on review of the proposed management activities and actions, and as stated in the Proposed RMP, 

BLM anticipates no changes in emissions and no impacts to air resources management for management 

actions relating to the following program areas: 

 Air Quality 

 Cave Resource Management 

 Cultural and Heritage Resource Management 

 Paleontological Resource Management 

 Social and Economic Concerns 

 Vegetation Resource Management 

 Water Resource Management 

 Wild Horse and Burro Management 

Accordingly, management actions under these program areas are presumed to conform and were not 

assessed further in the conformity evaluation. 
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April 2012 Air Quality General Conformity Evaluation 9 

For program areas other than those identified above, BLM used a qualitative analysis to identify the likely 

emission changes for each management action in terms of direction (increase/no change/decrease) 

compared to the No Action Alternative to assess the need for quantification of those changes. BLM 

reviewed the Management Alternatives in Chapter 2 of the Proposed RMP and the Impacts on Air 

Quality section in Chapter 4 for the qualitative analysis. BLM also reviewed the reasonably foreseeable 

development scenarios described in Chapter 4 of the Proposed RMP. These sections of the Proposed 

RMP provide information that can be used to determine whether emissions would change from current 

management (No Action Alternative) to the Proposed RMP (Alternative E), and if so in which direction. 

Where the Proposed RMP states the direction in which emissions would change, the conformity analysis 

reviewed and confirmed the RMP assessment. Where the Proposed RMP makes no such statement, 

BLM assessed the likely direction of the emissions change from the information given in the management 

actions, such as the number of acres or road-miles that would be subject to the various use restrictions. 

The qualitative analysis assumed that emissions would vary based on the quantity of resource (e.g., roadmiles or acres) made available, which may not necessarily be the case. For example, reductions in the 

number of road-miles available for recreational use may not necessarily decrease the amount of use (at 

least for small reductions) but may only lead to the same emissions being distributed over fewer roadmiles. An increase in available road-miles may not increase emissions but may only distribute the same 

amount of use and emissions over more road-miles, unless latent demand exists such that the increased 

mileage would attract additional use. However, the Proposed RMP assumption that emissions would 

vary directly with the quantity of resource made available is reasonable, and in cases like the example 

above may be conservative in the sense of underestimating decreases and overestimating increases in 

emissions. 

Where BLM identified management actions that could lead to increased emissions, the emissions for 

those program areas were quantified. The Identification of Emissions Changes by Program Area section 

below describes the methods and models used in the quantification of emissions for the individual 

program areas. BLM made the following assumptions to ensure the analysis would be conservative and 

provide a worst-case quantification of the total potential emissions increases associated with the 

Proposed RMP: 

 All activities would occur in the same year. 

 The emission rates for all vehicles and equipment are the maximum rates expected to occur 

during the planning period, i.e., the calendar year 2013 fleet was assumed. 

 Emissions from activities in all of the NAAs in the Planning Area are summed as if they occurred 

in the same NAA. 

 Decreases in emissions, which can be used to offset increases, were not quantified. 

The individual program areas include additional assumptions, as appropriate. 

Table 3 identifies if management actions associated with resource programs would result in a change in 

emissions compared to the No Action Alternative and the direction of the change. 
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April 2012 Air Quality General Conformity Evaluation 10 

Table 3. Summary of Emission Changes by Resource Program 

Resource Program 

Emissions Change under the Proposed RMP 

Lower Sonoran Decision 

Area 

Sonoran Desert 

National Monument 

Decision Area 

Air Quality No change No change 

Cave Resources No change No change 

Cultural and Heritage Resource Management No change No change 

Paleontological Resource Management No change No change 

Social and Economic Concerns No change No change 

Vegetation Resource Management No change No change 

Water Resource Management No change No change 

Wild Horse and Burro Management No change No change 

Lands and Realty No difference, or decrease Decrease 

Livestock Grazing Management No difference Decrease 

Minerals Management No difference No change 

Recreation Increase Increase 

Special Designations Management Decrease No change 

Travel Management Increase Increase 

Visual Resources Management Decrease Decrease 

Wildland Fire Management No difference No difference 

Wildlife and Special Status Species Decrease No change 

Note: No change means the program has no effect on air quality. No difference means the program may affect air quality but the impacts in 

the Proposed RMP would not differ from those in the No Action Alternative. 

RMP Resource Management Plan 

3.2. IDENTIFICATION OF EMISSIONS CHANGES BY DECISION AREA

The following sections discuss the potential changes in emissions within the two decision areas for each 

program area. For each program area the results of the qualitative analysis are explained. For program 

areas that could lead to increased emissions, the emissions increases are quantified. To facilitate easy 

reference to the Proposed RMP, the structure of these sections parallels that of the Chapter 4 sections 

of the Proposed RMP which presents program areas in alphabetical order. 

3.2.1. LOWER SONORAN DECISION AREA

3.2.1.1. LANDS AND REALTY

BLM is authorized under several authorities to acquire, dispose of, convey, and lease portions of the 

federally owned land it manages for the benefit of the national interest. Land tenure decisions select 

lands for retention, proposed disposal, acquisition, or lease. The lands and realty program for the 

Planning Area consists of three distinct parts: (1) land use authorizations (LUAs), which includes rightsof-way (ROWs) for such developments as roads, power lines, pipe lines, and renewable energy 
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April 2012 Air Quality General Conformity Evaluation 11 

development proposals; (2) land tenure adjustments (disposal and acquisition of lands); and (3) 

withdrawals, classifications, and segregations. Land tenure decisions must achieve the goals, standards, 

and objectives outlined in the land use plan. 

Potential air quality impacts would stem primarily from land use allocations or actions that would 

prevent or encourage the authorization of ROWs, leases, and land tenure actions in certain resourcerich areas. These allocations and actions could affect the potential development of energy facilities and 

utility corridors. 

Much of the reasonably foreseeable development is driven by infrastructure demand, especially in rural 

portions of the Planning Area that are developing and urbanizing. This demand is driven by market 

forces and would not differ between Alternative E and Alternative A. Any differences in emissions 

between Alternative E and Alternative A due to such infrastructure demand would occur as a result of 

land use allocations or management actions that could affect whether the infrastructure would be 

located in an NAA (e.g., renewable energy exclusion areas identified in the Proposed RMP). 

Table 4 presents lands and realty impacts in terms of acreage avoided and excluded. For the specific 

management actions included in Alternatives A and E, see the Lands and Realty section in Chapter 2 of 

the Proposed RMP. 

Table 4. Key Lands and Realty Allocations for the Lower Sonoran Decision Area 

Allocation 

Alternative 

A 

(No Action) B C D 

E 

(Proposed 

RMP) 

Land Use Authorizations: Utility-scale Renewable Energy Avoidance and Exclusion Areas

Acres avoided (moderate and 

high sensitivity conflict areas) 0 727,600 617,500 405,100 499,900

Acres excluded (prohibited 

areas) 105,000 160,100 293,800 519,400 394,200

Land Use Authorizations: Utility Corridors

Total Corridor Acres 134,328 134,328 95,203 72,153 82,301

Land Use Authorizations: Avoidance and Exclusion Areas (acres) 

LUA Avoidance Area 0 609,000 449,500 260,500 344,800

LUA Exclusion Area 105,100 143,700 271,900 593,600 295,100

Source: BLM 2012 

LUA land use authorization 

RMP Resource Management Plan 

Table 4 shows that the number of acres avoided or excluded to LUAs under Alternative E would 

increase compared to Alternative A, and the number of acres allocated to utility corridors would 

decrease under Alternative E compared to Alternative A. These restrictions (status as avoided, 

excluded, or not allocated to a utility corridor) reduce the potential for development and associated 

emissions in the identified areas. As a result, the number of acres avoided and excluded can be used as 

a proxy for the amount of development, and therefore emissions that could occur. 
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April 2012 Air Quality General Conformity Evaluation 12 

All lands and realty management actions specific to NAAs included in Alternative E are also included in 

Alternative A. Land use allocations and activity indicated in Table 4 for the entire LSDA are expected to 

be representative for the portions of the LSDA within the NAAs. The degree of restriction, as 

indicated by the number of acres avoided, excluded, or not allocated to a utility corridor would be 

greater under Alternative E. As a result, effects in the NAAs of lands and realty actions are expected to 

be less under Alternative E than Alternative A. Also, Alternative E includes additional measures to 

reduce fugitive PM emissions from surface disturbance that are not included in Alternative A. (Fugitive 

PM emissions are airborne particles generated by wind blowing across an exposed earth or material 

surface, or by the action of vehicle tires on the road or ground surface.) Because there would be no 

potential for emissions increases in the NAAs resulting from Alternative E, lands and realty actions in 

the LSDA do not require further conformity evaluation. 

3.2.1.2. LIVESTOCK GRAZING MANAGEMENT

The livestock grazing management program in the Planning Area carries out the intent of the Taylor 

Grazing Act of 1934, the Federal Land Policy and Management Act of 1976, and the Public Rangelands 

Improvement Act of 1978. Grazing permits or leases are valid for up to 10 years and authorize grazing 

within grazing districts on public land and other land administered by the BLM under Section 3 of the 

Taylor Grazing Act, and outside of grazing districts under Section 15 of the Taylor Grazing Act. 

Potential air quality impacts would result primarily from developing or maintaining livestock facilities, 

rangeland improvements, or other activities involving construction and surface disturbance. 

Management actions also may affect forage levels and the degree of human disturbance of livestock 

during recreational activities. 

Table 5 presents livestock grazing impacts in terms of acreage and animal unit months (AUMs). For 

specific management actions included in Alternatives A and E, see the Livestock Grazing section in 

Chapter 2 of the Proposed RMP. 

Table 5. Key Land Use Allocations for Livestock Grazing for the 

Lower Sonoran Decision Area 

Allocation 

Alternatives 

A 

(No Action) 

B 

(Reduced 

Perennial) 

C 

(Perennial Only/

No Ephemeral) 

D 

(Closed) 

E 

(Proposed 

RMP) 

Available Acres1 830,300 830,300 830,600 0 830,600

Unavailable Acres1 58,700 58,700 58,400 873,000 58,400

Total Acres 930,200 930,200 930,200 930,200 930,200

Total Proposed (AUMs2) 17,541 10,4313 17,541 0 17,541

1 Under each alternative, approximately 41,200 acres are either not under a Bureau of Land Management grazing permit or not part of a grazing 

allotment. These acres are not included in acreage available or unavailable for livestock grazing but are accounted for in total acres. 

2

 Animal Unit Month (AUM) is the amount of forage necessary for the sustenance of one cow or its equivalent for a period of 1 month. 

3

 Ephemeral AUMs are permitted on a case-by-case basis pursuant to the Special Ephemeral Rule. These AUMs are not included in the 

proposed perennial AUMs listed. 

Source: BLM 2012 

RMP Resource Management Plan 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 13 

Table 5 shows that the number of acres available for grazing, and the number of AUMs, would be nearly 

the same for Alternative E and Alternative A. The number of acres available and the total AUMs can be 

used as a proxy for construction and other activity, and therefore emissions that could occur. Land use 

allocations and activity indicated in Table 5 for the entire LSDA are expected to be representative for 

the portions of the LSDA within the NAAs. As a result, effects in the NAAs of livestock grazing actions 

are not expected to differ between Alternative E and Alternative A, and expected emissions in the 

NAAs for Alternative E would be the same as Alternative A. Because there would be no potential for 

emissions increases in the NAAs resulting from Alternative E compared to Alternative A, livestock 

grazing management in the LSDA does not require further conformity evaluation. 

3.2.1.3. MINERALS MANAGEMENT

The BLM supports mineral exploration and development on public lands in keeping with its multiple-use 

mandate. BLM manages three categories of minerals: 

 Locatable minerals, which include precious metals such as gold, silver, copper, and some 

industrial minerals such as gypsum and clay; 

 Leasable minerals, which include oil, natural gas, coal, sodium, and geothermal resources; and 

 Saleable minerals, which include sand and gravel, decorative rock, and other common minerals. 

Any development of the leasable, saleable, and locatable mineral resources could create short- term and 

periodic increased emissions from construction, vehicle traffic, and other activities. The location and 

intensity of such development would vary with the specific land use allocations and other management 

actions taken. According to the RMP, BLM’s management actions and the resulting potential changes in 

emissions would be the same for both Alternative A and Alternative E. Specific management actions 

may be more restrictive under Alternative E than under Alternative A, resulting in potentially lower 

emissions under Alternative E. The locations of future minerals development would depend on where 

suitable minerals deposits are found, and consequently may not, in some cases, be reasonably 

foreseeable. However, management actions associated with Alternative E would not shift minerals 

development from attainment areas into NAAs. 

Table 6 presents minerals management impacts in terms of acreage available for development. For the 

specific management actions included in Alternatives A and E, see the Minerals Management section in 

Chapter 2 of the Proposed RMP. 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 14 

Table 6. Key Land Use Allocations for Minerals Management in the 

Planning Area 

Allocation 

Alternative (BLM acres [percent]) 

A 

(No Action) B C D E (Proposed RMP) 

Acres of BLM-administered Surface Lands/Subsurface Mineral Estate 

Locatable Minerals

Total Closed 625,000 

(47%) 

627,350

(47%) 

627,300

(47%) 

1,018,900 

(76%) 

627,300

(47%) 

Total Open 713,300 

(53%) 

710,950

(53%) 

711,000

(53%) 

319,400 

(24%) 

711,000

(53%) 

Leasable Minerals

Total Closed 625,000 

(47%) 

627,300

(47%) 

627,300

(47%) 

1,209,900 

(90%) 

627,300

(47%) 

Total Open 713,300 

(53%) 

711,000

(53%) 

711,000

(53%) 

128,400 

(10%) 

711,000

(53%) 

Saleable Minerals

Total Closed 625,000 

(47%) 

649,700

(49%) 

818,300

(61%) 

1,181,000 

(88%) 

780,800

(58%) 

Total Available 713,300 

(53%) 

688,600

(51%) 

520,000

(39%) 

157,300 

(12%) 

557,500

(42%) 

Acres of Non-BLM Surface Land/BLM-administered Subsurface** 

(Split Estate) 

Total Closed 71,000 (34%) 

Total Open 139,000 (66%) 

Total 210,000 (100%) 

** The definition for Non-BLM Surface Land means lands not owned or administered by BLM, such as lands owned or administered by other 

Federal agencies, the State of Arizona, local municipalities, and private parties. 

Source: BLM 2012 

BLM Bureau of Land Management 

LSDA Lower Sonoran Decision Area 

RMP Resource Management Plan 

SDNM Sonoran Desert National Monument 

Table 6 shows that the number of acres available would be less for Alternative E than for Alternative A, 

and the number of acres closed would be greater for Alternative E than for Alternative A. The number 

of acres available can be used as a proxy for the construction, vehicle travel, and equipment operation 

associated with minerals development, and therefore emissions that could occur. Land use allocations 

and activity indicated in Table 6 for the entire LSDA are expected to be representative for the portions 

of the LSDA within the NAAs. As a result, expected emissions in the NAAs due to minerals 

management actions under Alternative E would be less than under Alternative A. Because there would 

be no potential for emissions increases in the NAAs due to Alternative E, minerals management actions 

in the LSDA do not require further conformity evaluation. 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 15 

3.2.1.4. RECREATION MANAGEMENT

Introduction 

Recreational experiences, setting, and activities in the Planning Area range from areas with primitive, 

roadless qualities to more modified and roaded natural areas. Within the Planning Area, visitors can, 

among other things, bike, camp, hike, ride horseback, backpack, hunt, target shoot, drive off-highway 

vehicles (OHVs) on vehicle routes, picnic, rock hound, geocache, observe cultural and historic sites, 

view/photograph wildlife, and experience wilderness areas. The dramatic increase in population within 

and surrounding the Planning Area has resulted in increased demands for outdoor recreational 

opportunities and management of public lands including the LSDA. Recreational activities in both 

Decision Areas have increased substantially due to newly developed residential communities adjacent to 

large blocks of public lands. This trend is especially pronounced in the northern portion of the LSDA 

which is nearer to developing areas of metropolitan Phoenix than the SDNM. The effect of increased 

population and development on the demand for recreational activities will occur equally with all RMP 

alternatives and does not, in itself, affect compliance of the RMP with the General Conformity Rule. 

Description of Impacts 

Potential air quality impacts would stem primarily from management actions that affect recreational 

resources and travel across public lands. (Potential air quality impacts associated with travel 

management are discussed separately below.) Under Instruction Memorandum No. 2011-004, the BLM 

established a three-tier system of Recreation Management Areas (RMAs) or lands managed for 

recreation: Special Recreation Management Areas (SRMA), Extensive Recreation Management Areas 

(ERMA) and Undesignated Lands (UL) which are defined as follows (refer to the Proposed RMP 

recreation sections for additional information): 

 SRMAs are administrative units where the existing or proposed recreation opportunities and 

recreation setting characteristics are recognized for their unique value and importance, or 

distinctiveness, especially as compared to other areas used for recreation. Within an SRMA, 

recreation management is recognized as the predominant planning focus where specific 

recreation opportunities and recreation setting characteristics are managed and protected on a 

long-term basis. 

 ERMAs are administrative units that require specific management consideration in order to 

address recreation use, demand or recreation and visitor services program investments. 

Management of ERMAs supports and sustains the principal recreation activities and the 

associated qualities and conditions of the ERMA. Management of ERMA areas is commensurate 

with the management of other resources and resource uses. 

 Public lands that are not designated as RMAs – ULs – are managed to meet basic recreation and 

visitor services and resource stewardship needs. Recreation is not emphasized; however, 

recreation activities may occur. Management of recreation and visitor services allows 

recreation uses that are not in conflict with the primary uses of these lands. 

 To effectively manage for differing expected outcomes within a RMA, SRMAs and ERMAs may 

be subdivided into separate Recreation Management Zones (RMZs). The RMZs provide for 

management emphasis tailored to expected recreation opportunities and outcomes over two or 

more specific geographic areas within an individual RMA. 

Map 3 (reproduced from RMP Map 2-12e) displays the locations of the RMAs proposed for 

Alternative E.
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Map 3. Alternative E Recreation Management 

Note: Reproduced from RMP Map 2-12e. 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 17 

Table 7 presents recreation management impacts in terms of acreage in managed recreation areas. For 

the specific management actions included in Alternatives A and E, see the Recreation Management 

section in Chapter 2 of the Proposed RMP. 

Table 7. Key Land Use Allocations for Recreation Management for the 

Lower Sonoran Decision Area 

Recreation Market Strategy 

Alternative (BLM acres) 

A 

(No Action) B C D 

E 

(Proposed 

RMP) 

Ajo SRMA ERMA ERMA UL ERMA 

Ajo Desert Zone -- RMZ RMZ UL RMZ 

Ajo Gateway Zone -- RMZ RMZ UL RMZ 

Arlington Trails -- ERMA In Gila Bend 

Mtns. ERMA UL ERMA 

Buckeye Hills East -- SRMA SRMA SRMA SRMA 

Buckeye Hills West -- ERMA ERMA ERMA ERMA 

Gila Bend Mountains -- ERMA ERMA UL ERMA 

Gila Trails SRMA Within portions of Lower Gila Historic Trails ERMA 

Gunsight Wash -- SRMA SRMA UL SRMA 

Lower Gila Historic Trails -- ERMA ERMA UL ERMA 

Painted Rock -- SRMA SRMA SRMA SRMA 

Saddle Mountain SRMA SRMA SRMA UL ERMA 

Sentinel Plain SRMA UL UL UL UL 

San Tan Mountains -- SRMA UL UL UL 

Source: BLM 2012

BLM Bureau of Land Management 

ERMA Extensive Recreation Management Area 

NHT National Historic Trail 

RMP Resource Management Plan 

RMZ Recreation Management Zone 

SRMA Special Recreation Management Area 

UL Undesignated Lands 

Table 7 shows that several RMAs managed under Alternative E are not managed under Alternative A. 

This indicates that the total number of acres in managed recreation areas would be greater for 

Alternative E than for Alternative A. Some of the management actions that BLM may take in these areas 

may involve activities that could generate emissions, such as construction of recreational facilities. BLM 

evaluated each recreation management action proposed under Alternative E to identify all reasonably 

foreseeable activities that could lead to increased emissions in NAAs compared to Alternative A. BLM 

identified several specific actions that could lead to increased emissions under Alternative E in the NAAs 

and quantified the potential emissions increases for these actions. 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 18 

Quantification of Emissions 

The recreation management actions that could increase emissions are construction of recreation 

facilities and the accompanying infrastructure (e.g., roads, drainage). The Proposed RMP describes the 

specific planned or reasonably foreseeable management actions that would involve construction. The 

facilities that could be built in the NAAs under Alternative E that would not be built under Alternative A 

would be located in the Buckeye Hills East RMZ and consist of the following: 

 Five 6-acre staging areas (a staging area typically includes a short gravel-surface access road, a 

gravel-surface parking lot, picnic tables, fire rings, toilets, kiosks and signs); 

 One 10-acre staging area; 

 Up to 4 miles of unpaved road; and 

 Up to 5 miles of single-track trail. 

Not all of these facilities would necessarily be constructed, nor would they necessarily be built in the 

same year, but they are identified as reasonably foreseeable based on discussions with BLM specialists. 

In order to provide a conservative (higher emissions) analysis for conformity purposes, emissions were 

estimated for these facilities assuming that all would be built in the same calendar year. In reality, they 

could be built at any time during the RMP planning period based on need and available funding. 

Construction of staging areas and roads would involve the use of construction equipment, typically 

backhoes, graders, rollers, and scrapers. Heavy trucks would be used to deliver gravel, concrete, and 

other materials. A water truck would be used on-site to suppress fugitive dust generation. Light trucks 

would be used to deliver tools and supplies and for crew transport. Workers would use their personal 

vehicles for commuting. Construction of single-track trails is done by hand without mechanized 

equipment, and the only source of emissions is the vehicles used to transport workers to the trailhead. 

The analysis included exhaust and fugitive dust emissions from each of these sources. 

BLM estimated emissions from vehicles using the EPA MOVES2010a model (EPA 2010), and emissions 

from construction equipment using the EPA NONROAD2008a model (EPA 2008). BLM estimated 

fugitive PM emissions using procedures in the EPA AP-42 guidance document (EPA 1995). The AP-42 

procedure for estimating fugitive PM emissions from unpaved roads requires data on the silt content of 

the road surface soil. The default input values given in AP-42 are not representative of the road surface 

conditions in the Planning Area, so BLM used values reported by Goossens and Buck (2009) for silt 

content. BLM estimated emissions for calendar year 2013 which is assumed to be the earliest year by 

which BLM could plan and fund the construction. The choice of 2013 is a conservative assumption 

because vehicle and equipment fleets are becoming cleaner over time as newer units, which are subject 

to stricter EPA emission standards and have lower emissions, replace older, higher-emitting units. The 

vehicle and equipment fleet that would be used in years after 2013 would have lower emissions than are 

estimated in this analysis. 

The analysis assumed that vehicles and equipment would operate for a single shift of standard duration 

per day (typically 10 hours, which can vary for specific activities or equipment). Due to the relatively 

small size of each facility, construction activities would be expected to occur over a period of no more 

than a few weeks per site. Appendix A provides further detail on the emissions estimates developed for 

the conformity analysis. 

Table 8 lists the estimated construction emissions for the planned facilities. PM10 emissions include both 

exhaust and fugitive PM. PM2.5 emissions were not estimated because no construction is projected to 

occur in PM2.5 NAAs. 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 19 

Table 8. Estimated Construction Emissions (tons) for Site and Road Development 

in the Buckeye Hills East RMZ 

Description CO NOx SO2 VOC PM10

Staging areas: five 6-acre and one 10-acre, 

total 40 acres 25.98 21.52 0.02 2.94 24.79 

Road: 4 miles, unpaved, 30-foot width 6.07 5.13 0.005 0.69 3.94 

Trails: 5 miles, single-track 0.04 0.01 0.0001 0.001 0.0003 

Total 32.09 26.65 0.02 3.64 28.73 

Note: Data may not sum to total due to rounding. 

CO carbon monoxide 

NOx nitrogen oxides 

PM particulate matter 

RMZ Recreation Management Zone 

SO2 sulfur dioxide 

VOC volatile organic compound 

BLM anticipates that the presence of these facilities may, by making the area more attractive for 

recreation, contribute to an increase in visitation and use. However, BLM anticipates that most of any 

increase in visitation would be attributable to the system of designated OHV travel routes that BLM 

plans to establish in the Buckeye Hills East RMZ, and to potential BLM efforts to increase marketing of 

the area to the public. In addition, BLM may allow OHV motorized, competitive speed events (i.e., 

races) in designated areas of the LSDA. Because of their relationship to the designated route system, 

emissions due to increased visitation and OHV races are considered under the Travel Management 

program area below. 

3.2.1.5. SPECIAL DESIGNATIONS MANAGEMENT

Special Area Designations describe areas that have special values that warrant or require special 

management or protection. These areas, which are specifically addressed through the RMP planning 

process, include Areas of Critical Environmental Concern (ACECs), Scenic and Backcountry Byways, 

Wilderness Areas, and areas designated as part of the Wild and Scenic River System or National 

Historic Trails (NHTs). ACECs are areas where unique resources exist, making them worthy of a 

higher level of concern and protection. Once an ACEC is designated, the focus of management is to 

preserve and restore the resources that inspired the recommendation for designation. 

Seventeen special designation areas currently exist within the Planning Area. Five are located within the 

LSDA: Sierra Estrella, Signal Mountain, and Woolsey Peak wildernesses; Juan Bautista de Anza NHT; 

and Coffeepot Botanical ACEC. Impacts would stem primarily from management of resource values 

associated with existing or proposed ACECs. 

Table 9 presents potential impacts in terms of acreage managed as ACECs. For the specific management 

actions included in Alternatives A and E, see the ACEC section in Chapter 2 of the Proposed RMP. 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 20 

Table 9. Key Land Use Allocations for Special Designations in the 

Lower Sonoran Decision Area: ACECs 

ACEC Name 

Alternative (BLM Acres) 

A 

(No Action) B C D E (Proposed RMP) 

Coffeepot Botanical 8,900 8,900 Not Designated 8,900 

Coffeepot-Batamote Not Designated 63,300 77,600 Not Designated 

Cuerda de Lena Not Designated 60,900 58,500 

Lower Gila Terraces and 

Historic Trails Not Designated 82,500 82,500 

Saddle Mountain Not Designated 48,500 48,500 

Source: BLM 2012 

ACEC Area of Critical Environmental Concern 

BLM Bureau of Land Management 

RMP Resource Management Plan 

Table 9 shows that the number of acres managed as ACECs in the LSDA would be greater for 

Alternative E than for Alternative A. The number of acres can be used as a proxy for the intensity of 

activities, and therefore emissions that could occur. Allowable activities in ACECs are more restricted 

than in areas not designated as ACECs, and as a result emissions are expected to be lower. With 

respect to the NAAs, the only ACEC-designated acreage that is located in an NAA is a portion of the 

Coffeepot-Batamote, a portion of the Cuerda de Lena, most of the Lower Gila Terraces and Historic 

Trails, and a very small portion of the Saddle Mountain ACEC. There is ACEC-designated acreage in an 

NAA under Alternative E that would not be ACEC-designated under Alternative A. In contrast, all 

ACEC-designated acreage in an NAA under Alternative A would also be ACEC-designated under 

Alternative E. As a result, the effects in the NAAs of ACEC designation are expected to lead to lower 

emissions under Alternative E compared to Alternative A. Because there would be no potential for 

emissions increases in the NAAs due to Alternative E, special designations management actions in the 

LSDA do not require further conformity evaluation. 

3.2.1.6. TRAVEL MANAGEMENT

Introduction 

Travel management strives to provide manageable access to public lands while balancing resource 

protection. The allocation of areas as open, closed or limited to OHVs directs the management 

approach for vehicular travel on public lands. Implementation-level actions such as designating routes as 

part of a planned network help create a balance between human use and resource protection. 

Description of Impacts 

From an air quality perspective the predominant impacts from travel are exhaust emissions from motor 

vehicles, both on-road and off-road, and fugitive PM emissions generated by the action of vehicle tires 

on the road or ground surface. The level of vehicle usage, and thus the emissions, would vary with 

BLM’s RMP-level travel management decisions for designating areas as open, limited, or closed to OHV 

use, and the implementation-level decisions for designating particular routes as open, limited, or closed 

to public use. Increasing restrictions to motorized recreation and access would result in a progressively 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 21 

limited, motorized route network and reduced access. Limitations on routes and access would tend to 

reduce vehicle emissions by decreasing vehicle usage overall and by confining vehicles to designated 

routes on which BLM could concentrate maintenance and dust control efforts. Impacts from not having 

a route system could include the continued establishment of unwanted access points and routes leading 

into public lands, which would result in higher emissions, especially fugitive PM from increased ground 

disturbance. 

Table 10 presents travel management impacts in terms of acreage under different management regimes. 

For the specific management actions included in Alternatives A and E, see the Travel Management 

section in Chapter 2 of the Proposed RMP. 

Table 10. Key Travel Management Allocations for the Lower Sonoran Decision Area 

Decision 

Alternative (BLM acres) 

A 

(No Action) B C D E (Proposed RMP) 

Open 0 40 0 0 0 

Closed 100,000 91,100 91,100 342,700 91,100 

Limited to existing roads 

and trails 830,200 0 0 0 0 

Limited to Designated 

Routes 0 839,060 839,100 587,500 839,100 

Total 930,200 930,200 930,200 930,200 930,200 

Source: BLM 2012 

BLM Bureau of Land Management 

RMP Resource Management Plan 

Table 10 shows that although the number of acres closed to OHV travel and limited to existing roads 

and trails would be less for Alternative E than for Alternative A, the number of acres limited to 

designated routes would be much greater for Alternative E than for Alternative A. Although the 

increase in acreage limited to designated routes suggests that, in general, the potential for emissions 

would be lower under Alternative E than Alternative A, BLM expects that the establishment of a 

designated route system could lead to increased visitation in certain areas, specifically the Buckeye Hills 

East RMZ, and correspondingly increased emissions from vehicle usage under Alternative E. BLM 

anticipates that outside the Buckeye Hills East RMZ, Alternative E would result in no effect or a slight 

decrease in user activity compared to Alternative A. This decrease would reduce emissions outside the 

Buckeye Hills East RMZ but has not been quantified in this conformity analysis. For the Buckeye Hills 

East RMZ, which is within the NAAs, Alternative E would designate routes and limit use to the 

designated routes. Designation can make the availability of an area easier to publicize and so can attract 

new visitors who may not have been aware of the area as a recreation destination. 

The designated route system would prohibit the use of undesignated routes. This would confine visitors 

to the designated area and thus reduce usage in other areas that are outside of the designated route 

system. Those visitors who previously used the areas outside of the designated route system would be 

shifted to the designated area, increasing the total usage of the designated route system. Because the 

increased use would occur within the NAAs while the decreases would occur predominantly outside 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 22 

the NAAs, the resulting increase in emissions must be considered in the conformity evaluation even 

though it represents only a shift in location and not an increase in the LSDA as a whole. 

In addition, designating routes would reduce fugitive PM emissions because users would no longer be 

allowed to travel off trail, breaking new ground and eroding it. The amount of reduction in off-trail 

travel and fugitive PM emissions is difficult to estimate and currently available data are insufficient to do 

so. This potential reduction has not been quantified in the conformity evaluation. 

Quantification of Emissions 

It is reasonably foreseeable that establishment of a designated route system in the Buckeye Hills East 

RMZ could lead to increases in visitation and associated emissions. To estimate the increase in 

emissions in the Buckeye Hills East RMZ as a result of the designated route system (including increased 

visitation at the planned new facilities discussed above in Recreation Management), BLM used a database 

of OHV counts gathered at the BLM Boulders OHV Area, located in the Hieroglyphic Mountains 

approximately 20 miles northwest of Phoenix. The BLM processed the vehicle count data using the 

Recreation Management Information System to estimate seasonal and annual visitation levels. Based on 

comparison of conditions and usage patterns in the Boulders OHV Area and the Buckeye Hills East 

RMZ, BLM staff estimated the increase in visitation and vehicle use, and the resulting emissions 

increases, that would be expected at Buckeye Hills East under Alternative E including the designated 

route system. 

BLM may issue permits for OHV competitive, motorized speed events (i.e., races) in the LSDA. BLM 

considers applications for permits for these events on a case-by-case basis. In recent years BLM has not 

received applications or has denied them. With the increase in travel management actions under 

Alternative E, BLM anticipates that the number of applications may increase, and accordingly emissions 

increases from OHV races are reasonably foreseeable. Races would be held only at designated 

locations, one of which is the Buckeye Hills East RMZ located within the NAA. BLM anticipates a 

maximum of one race event per year. 

Based on past experience, the BLM made the following assumptions to estimate the emissions from an 

annual OHV race event: 

 The event would consist of a 200-mile race for trucks and other 4-wheel vehicles and a 100-mile 

race for motorcycles; 

 Each race would take place on a 40-mile course; 

 Each race would have 100 participants; and 

 The event would attract 100 vehicles for organizers, support, volunteers, and concessionaires, 

and 500 vehicles for spectators. 

Table 11 lists the estimated emissions due to increased visitation and OHV races. PM10 emissions 

include both exhaust and fugitive PM. PM2.5 emissions were not estimated because no increased 

visitation or OHV races are projected to occur in PM2.5 NAAs. 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 23 

Table 11. Estimated Emissions (tons per year) due to Increased Visitation and 

OHV Races in the Buckeye Hills East RMZ 

Description CO NOx SO2 VOC PM10

Increased visitation (vehicle use) 2.94 0.40 0.003 0.31 7.37 

OHV races 0.84 0.05 0.001 0.54 9.75 

Total 3.78 0.45 0.004 0.85 17.12 

CO carbon monoxide 

NOx nitrogen oxides 

OHV Off-highway vehicle 

PM particulate matter 

RMZ Recreation Management Zone 

SO2 sulfur dioxide 

VOC volatile organic compound 

3.2.1.7. VISUAL RESOURCES MANAGEMENT

The Planning Area is generally located in the Basin and Range Physiographic Province. The scenery of 

the LSDA includes rugged mountains, striking cliff formations, foothills, mesas, washes, bajadas, and 

broad plains. Major visual intrusions include highways and other vehicle routes, evidence of mining and 

ranching, and utility ROWs. 

Outstanding scenic landscapes administered by the BLM provide a place to escape and enjoy the beauty 

of nature. They also are used for a multitude of other activities, including recreation, mining, grazing, 

and road development. Many of these activities have the potential to disturb the landscape and to have 

impacts on scenic values. BLM is required to manage public lands to protect their scenic values. To 

consistently evaluate its lands within their regional context, BLM developed the Visual Resource 

Management (VRM) program. BLM uses the VRM process to manage the scenic quality of the landscape 

and reduce the impact of development on the scenery. The BLM manages landscapes based on visual 

indicators defined in the Visual Resource Inventory Handbook H-8410-1. Using the indicators, BLM 

assigns land areas to four VRM management classes: 

 Class I: The objective of this class is to preserve the existing character of the landscape. This 

class provides for natural ecological changes; however, it does not preclude very limited 

management activity. The level of change to the characteristic landscape should be very low and 

must not attract attention. 

 Class II: The objective of this class is to retain the existing character of the landscape. The level 

of change to the characteristic landscape should be low. Management activities may be seen but 

should not attract attention from the casual observer. 

 Class III: The objective of this class is to partially retain the existing character of the landscape. 

The level of change to the characteristic landscape should be moderate. Management activities 

may attract attention but should not dominate the view of the casual observer. 

 Class IV: The objective of this class is to provide for management activities that require major 

modification of the existing character of the landscape. The level of change to the characteristic 

landscape can be high. These management activities may dominate the view and be the major 

focus of viewer attention. 

Potential air quality impacts would not stem directly from visual resources management actions, but 

indirectly from changes in resource use activities on an area of land, and their associated emissions, that 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 24 

result from changes in the VRM Class assignment of the area. VRM Class I is the most restrictive and, in 

general, is expected to result in the lowest level of emissions from resource use activities and the 

associated management actions. VRM Classes II, III, and IV are progressively less restrictive. VRM Class 

IV, in general, is expected to result in the highest level of emissions from resource use activities and the 

associated management actions. 

Table 12 presents visual resources management impacts in terms of acreage allocated to each VRM 

Class. For the specific management actions included in Alternatives A and E, see the Visual Resources 

section in Chapter 2 of the Proposed RMP. 

Table 12. Land Use Allocations for Visual Resources Management for the 

Lower Sonoran Decision Area 

VRM Class 

Alternative (BLM Acres) 

A 

(No Action) B C D E (Proposed RMP) 

Class I 91,800 91,800 91,800 91,800 91,800 

Class II 116,300 64,800 387,800 622,400 65,500 

Class III 279,600 551,000 385,600 192,000 554,800 

Class IV 442,500 222,600 65,000 24,000 218,100 

Source: BLM 2012 

BLM Bureau of Land Management 

RMP Resource Management Plan 

VRM Visual Resource Management 

Table 12 shows that under Alternative E there would be a relatively large increase in VRM Class III 

acreage, a relatively large decrease in VRM Class IV acreage, and a smaller decrease in VRM Class II 

acreage, compared to Alternative A. The net effect of Alternative E would be a shift in acreage from 

less-restrictive to more-restrictive VRM classes. As noted above, such a shift is expected to result in 

lower potential for resource use activities that would increase emissions. Land use allocations and 

activity indicated in Table 12 for the entire LSDA are expected to be representative for the portions of 

the LSDA within the NAAs. Because there would be no potential for emissions increases in the NAAs 

due to VRM Class allocations under Alternative E, visual resources management actions in the LSDA do 

not require further conformity evaluation. 

3.2.1.8. WILDLAND FIRE MANAGEMENT

The RMP indicates that air quality impacts from fire and fuels management would not differ by 

alternative. This suggests that no difference in emissions associated with fire and fuels management 

actions would be expected between Alternative E and Alternative A. Because there would be no 

potential for emissions increases due to fire and fuels management, fire and fuels management actions in 

the LSDA do not require further conformity evaluation. 

3.2.1.9. WILDLIFE AND SPECIAL STATUS SPECIES

BLM manages vegetation and wildlife populations in the Planning Area to ensure high-quality wildlife 

habitat and to protect water resources and watershed conditions. Management actions and other 

activities on acreage managed as wildlife habitat area generally are subject to greater development 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 25 

restrictions, resulting in decreased potential for emissions compared to areas not managed as wildlife 

habitat areas. A possible exception, discussed below, is small-scale construction of facilities such as 

wildlife water developments (e.g., catchments or springs) to support wildlife populations. 

Table 13 presents potential habitat management impacts in terms of acreage managed as wildlife habitat 

areas. For the specific management actions included in Alternatives A and E, see the Wildlife and Special 

Status Species section in Chapter 2 of the Proposed RMP. 

Table 13. Key Land Use Allocations for Wildlife Habitat for the 

Lower Sonoran Decision Area 

Wildlife Habitat Area 

Alternative (BLM Acres) 

A 

(No Action) B C D E (Proposed RMP) 

Batamote Mountains 0 0 62,900 0 0 

Cuerda de Lena 0 0 58,500 0 0 

Gila Bend Mountains 0 0 255,700 255,700 255,700 

Saddle Mountain 0 0 48,800 0 0 

Total 0 0 425,900 255,700 255,700 

Source: BLM 2012 

BLM Bureau of Land Management 

RMP Resource Management Plan 

Table 13 shows that the number of acres managed as wildlife habitat areas would be greater for 

Alternative E than for Alternative A. The number of acres available can be used as a proxy for surfacedisturbing activities, and therefore emissions that could occur. Land use allocations and activity 

indicated in Table 13 for the entire LSDA are expected to be representative for the portions of the 

LSDA within the NAAs. As a result, effects in the NAAs of wildlife habitat management actions, and 

their expected emissions, would be less with Alternative E than with Alternative A. 

Although the Proposed RMP mentions the possibility of construction of new wildlife waters under 

Alternative E that are not included under Alternative A, BLM staff estimate that this possibility is remote 

and no construction of new wildlife waters is planned or expected to occur. Consequently, no 

emissions increases are anticipated as a result of construction of new wildlife waters. 

Because there would be no potential for emissions increases in the NAAs due to Alternative E, priority 

wildlife and special species management actions in the LSDA do not require further conformity 

evaluation. 

3.2.2. SONORAN DESERT NATIONAL MONUMENT DECISION AREA

3.2.2.1. LANDS AND REALTY

BLM is authorized under several authorities to acquire, dispose of, convey, and lease portions of the 

federally owned land it manages for the benefit of the national interest. As discussed in Section 3.2.1.1 

of this report for the LSDA, potential air quality impacts in the SDNM would stem primarily from land 

use allocations or actions that would prevent the authorization of ROWs, leases, and land tenure 

actions in certain resource-rich areas. 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 26 

Table 14 presents lands and realty impacts in terms of acreage avoided and excluded for LUAs and land 

tenure adjustments. For the specific management actions included in Alternatives A and E, see the 

Lands and Realty section in Chapter 2 of the Proposed RMP. 

Table 14. Key Lands and Realty Allocations for the SDNM 

Decision 

Alternative 

A 

(No Action) B C D E (Proposed RMP) 

Land Use Authorizations: Utility-scale Renewable Energy Avoidance and Exclusion Areas (acres)

The SDNM is excluded from any potential utility-scale renewable energy development within all alternatives. 

Land Use Authorizations: Utility Corridors (Width/Length miles) 

Santa Rosa-Gila Bend 1.0/18.1 1.0/18.1 0.5*/17.9* N/A N/A 

Interstate 8 1.0/21.1 1**/21.1 0.5*/21.1* N/A N/A 

Tucson Electric Power 1.0/7.4 1.0/7.4 N/A N/A N/A 

Total Corridor Acres 32,900 32,900 14,900 N/A N/A 

Multiuse utility corridor widths and lengths are measured as they cross BLM-administered lands only. Multiuse 

utility corridors are simply referred to as utility corridors within Alternative A and would not include 

transportation facilities. 

*Indicates that the multiuse utility corridor will only permit underground facilities. 

**Indicates that a portion of the multiuse utility corridor narrows to a 0.5-mile wide (south of the Interstate 8 

highway centerline) as it passes along the length of the South Maricopa Mountains Wilderness. 

Land Use Authorizations: Avoidance and Exclusion Areas (acres) 

LUA Avoidance Area N/A 293,600 181,400 N/A N/A 

LUA Exclusion Area 164,900 192,800 305,000 486,400 486,400 

Land Use Authorizations: Communication Sites

No communication sites are designated in the SDNM. 

Land Tenure (acres)

Disposal 

No lands are designated as being suitable for disposal within the monument. Exchanges 

for lands within the SDNM for other private lands within the SDNM’s boundaries would 

be permitted if they further improve the management of SDNM objects and present no 

net loss to existing objects that will be impacted by the exchange. 

R&PP Leased No lands are presently leased under the R&PP Act within the SDNM, therefore no acres 

were identified. 

Acquisition Private and state lands would be acquired as available and funds allow, on a willing seller, 

willing buyer basis. 

Retention All 486,400 acres of public land would be retained. 

Source: BLM 2012 

BLM Bureau of Land Management 

LSDA Lower Sonoran Decision Area 

LUA Land Use Authorization 

R&PP Recreation and Public Purpose 

RMP Resource Management Plan 

SDNM Sonoran Desert National Monument 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 27 

Table 14 shows that the number and total area of designated utility corridors would be less for 

Alternative E than for Alternative A, and the number of acres managed as LUA avoidance or exclusion 

areas would be greater for Alternative E compared to Alternative A. The number of acres under the 

various allocations can be used as a proxy for the amount of construction and other activity, and 

therefore emissions that could occur. Land use allocations and activity indicated in Table 14 for the 

entire SDNM are expected to be representative for the portions of the SDNM within the NAAs. As a 

result, effects in the NAAs of lands and realty actions with Alternative E are expected to be less than 

with Alternative A. Because there would be no potential for emissions increases in the NAAs due to 

Alternative E, lands and realty actions in the SDNM do not require further conformity evaluation. 

3.2.2.2. LIVESTOCK GRAZING MANAGEMENT

The livestock grazing management program in the Planning Area carries out the intent of the Taylor 

Grazing Act of 1934, the Federal Land Policy and Management Act of 1976, and the Public Rangelands 

Improvement Act of 1978. As discussed in Section 3.2.1.2 of this report for the LSDA, potential air 

quality impacts in the SDNM would stem primarily from developing or maintaining livestock facilities, 

rangeland improvements, or other activities involving construction and surface disturbance. 

Management actions also may affect forage levels and the degree of human disturbance of livestock 

during recreational activities. 

Table 15 presents livestock grazing impacts in terms of acreage and AUMs. For the specific management 

actions included in Alternatives A and E, see the Livestock Grazing section in Chapter 2 of the Proposed 

RMP. 

Table 15. Key Land Use Allocations for Livestock Grazing for the SDNM 

Allocation (acres) 

Alternatives 

A 

(No Action) 

B 

(Reduced 

Perennial) 

C 

(Perennial Only/ 

No Ephemeral) 

D 

(Closed) 

E 

(Proposed RMP) 

Available 252,500 243,500 207,500 0 156,330

Unavailable 233,900 242,900 278,900 486,400 330,070

Total Acres within SDNM 486,400 486,400 486,400 486,400 486,400

Total Proposed (AUMs1) 8,703 5,3212 7,092 0 3,114

1

 AUMs shown are prorated and reduced by 7,884 from the total permitted use due to the allotment closures south of I-8. In Alternatives B 

and E, AUMs were further prorated using current data compared to forage allocations suggested in the Lower Gila South RMP Resource 

Protection Alternative. 

2

 Ephemeral AUMs are permitted on a case-by-case basis pursuant to the Special Ephemeral Rule. 

Source: BLM 2012 

AUM Animal Unit Month 

RMP Resource Management Plan 

SDNM Sonoran Desert National Monument 

Table 15 shows that the number of acres available for grazing and the number of AUMs would be less 

under Alternative E than under Alternative A. The number of acres available and the total AUMs can be 

used as a proxy for the construction and other activity, and therefore emissions that could occur. Land 

use allocations and activity indicated in Table 15 for the entire SDNM are expected to be representative 

for the portions of the SDNM within the NAAs. As a result, effects in the NAAs from livestock grazing 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 28 

actions would be less under Alternative E than under Alternative A, and expected emissions in the 

NAAs under Alternative E would also be less than under Alternative A. Because there is no potential 

for emissions increases in the NAAs due to Alternative E, livestock grazing actions in the SDNM do not 

require further conformity evaluation. 

3.2.2.3. MINERALS MANAGEMENT

The RMP indicates that the SDNM is withdrawn from new minerals development under all alternatives. 

The withdrawal was established in the proclamation that established the SDNM. This indicates that no 

difference in emissions associated with minerals management actions would be expected between 

Alternative E and Alternative A. Because there would be no potential for emissions increases due to 

minerals management, minerals management actions in the SDNM do not require further conformity 

evaluation. 

3.2.2.4. RECREATION MANAGEMENT

Introduction 

Recreational experiences, setting, and activities in the Planning Area range from areas with primitive, 

roadless qualities to more modified and roaded natural areas. As discussed in Section 3.2.1.4 of this 

report for the LSDA, potential air quality impacts would result primarily from management actions that 

affect recreational resources and travel across public lands. Potential air quality impacts associated with 

travel management in the SDNM are discussed separately below. Table 16 presents recreation 

management impacts in terms of acreage in managed areas. For the specific management actions 

included in Alternatives A and E, see the Recreation Management section in Chapter 2 of the Proposed 

RMP. 

Table 16. Key Land Use Allocations for Recreation Management for the SDNM 

Recreation Market Strategy 

Alternative (BLM acres) 

A 

(No 

Action) B C D 

E 

(Proposed 

RMP) 

Gila Trails SRMA Portions of Juan Bautista de Anza NHT RMZ 

Sonoran Desert -- ERMA ERMA UL ERMA 

Desert Back Country RMZ -- RMZ RMZ UL RMZ 

Juan Bautista de Anza NHT RMZ -- RMZ RMZ UL RMZ 

Source: BLM 2012

BLM Bureau of Land Management 

ERMA Extensive Recreation Management Area 

NHT National Historic Trail 

RMP Resource Management Plan 

RMZ Recreation Management Zone 

SRMA Special Recreation Management Area 

SDNM Sonoran Desert National Monument 

UL Undesignated Land 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 29 

Description of Impacts 

Table 16 shows that the areas in the SDNM managed for recreation under Alternative E are not 

managed under Alternative A, with the exception of Gila Trails which is managed for recreation under 

both alternatives. This indicates that the total number of acres in managed recreation areas would be 

greater for Alternative E than for Alternative A. Some of the management actions that BLM may take in 

these areas may involve activities that could generate emissions, such as construction of recreational 

facilities. BLM evaluated each recreation management action proposed under Alternative E to identify all 

reasonably foreseeable activities that could lead to increased emissions in NAAs compared to 

Alternative A. 

The Proposed RMP describes the specific planned or reasonably foreseeable management actions that 

would involve construction or similar activities. BLM identified the actions that could occur in the 

NAAs under Alternative E that would not occur under Alternative A. The recreation management 

actions that could increase emissions are construction of pulloff areas to allow vehicles to park next to 

existing roads, improvement of existing staging areas, and increased maintenance on roads used for 

visitor recreation. The improvements to the existing staging areas would include laying gravel on the 

parking lots and access roads and “hardening” or stabilizing the surface to reduce dust generation. 

These actions would be located at sites in the Anza NHT corridor and would consist of the following: 

 Construct 3 acres of pulloffs; 

 Improve two 1.5-acre existing staging areas; and 

 Increase maintenance levels on 12 miles of roadway.1

BLM quantified potential emission increases for these actions. 

Quantification of Emissions 

Not all of the recreation actions in the SDNM would necessarily be implemented, nor would they 

necessarily be implemented in the same year but they are identified as reasonably foreseeable based on 

discussions with BLM specialists. In order to provide a conservative analysis for conformity purposes, 

emissions were estimated for these facilities assuming that all would be implemented in the same 

calendar year. In reality, they could be implemented at any time during the RMP planning period based 

on need and available funding. 

Construction, improvement, and maintenance activities would use the same equipment and methods 

that are discussed in Section 3.2.1.4 of this report for the LSDA. The emissions analysis associated with 

recreation actions in the SDNM used the same assumptions and methods as discussed in Section 3.2.1.4 

for the LSDA. Due to the relatively small size of each facility, construction and improvement activities 

would be expected to occur over a period of no more than a few weeks per site. Road maintenance 

activities would be scheduled as needed or on a continuing basis. 

 

1

 The General Conformity Rule contains an exemption for “Routine maintenance and repair activities, including repair and 

maintenance of administrative sites, roads, trails, and facilities.” (40 CFR § 93.153[c][iv].) At present it is unknown 

whether BLM will plan this maintenance such that it would be considered routine. For conservatism the proposed increase 

in maintenance was treated as a non-routine, but annual, activity subject to conformity. 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 30 

Table 17 lists the estimated construction emissions for the reasonably foreseeable activities. PM10

emissions include both exhaust and fugitive PM. PM2.5 emissions were not estimated because no 

construction would occur in PM2.5 NAAs. Unlike one-time construction emissions, emissions from the 

increased road maintenance would recur according to BLM’s maintenance schedule and so are included 

in the estimates of recurring emissions presented under Travel Management below rather than in 

Table 17. 

Table 17. Estimated Construction Emissions (tons) for Site and Road Development 

in the Anza NHT Corridor 

Description CO NOx SO2 VOC PM10

Construct pulloffs: 3 acres total area 6.20 5.07 0.004 0.71 0.79 

Improve existing staging areas: two 1.5-acre areas 0.09 0.09 0.0002 0.01 0.26 

Total 6.29 5.17 0.004 0.72 1.05 

Note: Data may not sum to total due to rounding. 

CO carbon monoxide 

NHT National Historic Trail 

NOx nitrogen oxides 

PM particulate matter 

SO2 sulfur dioxide 

VOC volatile organic compound 

BLM anticipates that the presence of these facilities and improvements may, by making the area more 

attractive for recreation, contribute to an increase in visitation. Because of their basis in vehicle travel, 

emissions due to increased visitation are considered under the Travel Management program area below. 

3.2.2.5. SPECIAL DESIGNATIONS MANAGEMENT

Special Area Designations describe areas that have special values that warrant or require special 

management or protection, as discussed in Section 3.2.1.5 of this report. Seventeen special designation 

areas currently exist within the Planning Area. Six occur within the SDNM Decision Area and include 

the SDNM itself plus the North and South Maricopa Mountains and Table Top wildernesses; Vekol 

Valley Grasslands ACEC; and Juan Bautista de Anza NHT. Impacts would stem primarily from 

management of resource values associated with existing or proposed ACECs. 

Table 18 presents potential impacts in terms of acreage managed under ACECs. For the specific 

management actions included in Alternatives A and E, see the ACEC section in Chapter 2 of the 

Proposed RMP. 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 31 

Table 18. Key Land Use Allocations for Special Designations in the 

SDNM: ACECs 

ACEC Name 

Alternative (BLM Acres) 

A 

(No Action) B C D E (Proposed RMP) 

Vekol Valley Grasslands 3,500 No ACEC designation 

Source: BLM 2012 

ACEC Area of Critical Environmental Concern 

BLM Bureau of Land Management 

RMP Resource Management Plan 

SDNM Sonoran Desert National Monument 

Table 18 shows that under Alternatives B-E the Vekol Valley Grasslands is not managed as an ACEC. 

The Vekol Valley Grasslands is not located within an NAA, and accordingly actions with respect to the 

Vekol Valley Grasslands are not subject to the General Conformity Rule. Because there would be no 

potential for emissions increases in the NAAs due to Alternative E, special designations management 

actions in the SDNM do not require further conformity evaluation. 

3.2.2.6. TRAVEL MANAGEMENT

Introduction 

Travel management strives to provide manageable access to public lands while balancing resource 

protection. As discussed in Section 3.2.1.6 of this report for the LSDA, the allocation of areas as open, 

closed or limited to OHVs directs the management approach for vehicular travel on public lands. 

Description of Impacts 

Table 19 presents travel management impacts in terms of acreage under different management regimes. 

For the specific management actions included in Alternatives A and E, see the Travel Management 

section in Chapter 2 of the Proposed RMP. 

Table 19. Key Travel Management Allocations for the SDNM 

Decision 

Alternative (BLM acres) 

A 

(No Action) B C D E (Proposed RMP) 

Open 0 0 0 0 0

Closed 161,200 157,700 157,700 313,600 157,700

Limited to existing roads and 

trails 325,200 0 0 0 0

Limited to Designated Routes 0 328,700 328,700 172,800 328,700

Total 486,400 486,400 486,400 486,400 486,400

Source: BLM 2012 

BLM Bureau of Land Management 

RMP Resource Management Plan 

SDNM Sonoran Desert National Monument 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 32 

Table 19 shows that although the number of acres closed to OHV travel and limited to existing roads 

and trails would be less for Alternative E than for Alternative A, the number of acres limited to 

designated routes would be much greater under Alternative E than under Alternative A. Although the 

increase in acreage limited to designated routes suggests that, in general, the potential for emissions 

would be lower under Alternative E than Alternative A, BLM expects that the planned improvements to 

existing facilities and increased road maintenance could lead to increased visitation in the Anza NHT 

RMZ. 

Quantification of Emissions 

It is reasonably foreseeable that the improved facilities and road maintenance in the Anza NHT RMZ 

could lead to increases in visitation and associated emissions. To estimate the increase in emissions in 

the Anza NHT RMZ as a result of increased visitation, BLM used the same method as described in 

Section 3.2.1.6 of this report. Based on comparison of conditions and usage patterns in the Boulders 

OHV Area and the Anza NHT RMZ, BLM staff estimated the increase in visitation and vehicle use, and 

the resulting emissions increases, that would be expected in the Anza NHT RMZ under Alternative E. 

OHV races would not be permitted in the SDNM under Alternative E so there would be no emissions 

resulting from OHV races in the NAAs of the SDNM. 

Table 20 lists the estimated recurring emissions for the reasonably foreseeable activities. PM10

emissions include both exhaust and fugitive PM. PM2.5 emissions were not estimated because no 

increased visitation is projected to occur in PM2.5 NAAs. Road maintenance emissions are assumed to 

occur annually because BLM’s maintenance schedule is not yet known. 

Table 20. Estimated Recurring Emissions (tons per year) due to Increased Visitation 

and Road Maintenance in the Anza NHT RMZ 

Description CO NOx SO2 VOC PM10

Increased visitation (visitor vehicle use) 0.42 0.08 0.00 0.01 2.77 

Increased road maintenance (construction 

equipment and vehicles)1 0.84 0.05 0.00 0.54 9.75 

Total 1.26 0.14 0.001 0.56 12.52 

1

The General Conformity Rule contains an exemption for “Routine maintenance and repair activities, including repair and maintenance of 

administrative sites, roads, trails, and facilities.” (40 CFR § 93.153[c][iv].) At present it is unknown whether the Bureau of Land Management 

will plan this maintenance such that it would be considered routine. For conservatism the proposed increase in maintenance was treated as a 

non-routine, but annual, activity subject to conformity. 

CO carbon monoxide 

NHT National Historic Trail 

NOx nitrogen oxides 

PM particulate matter 

RMZ Recreation Management Zone 

SO2 sulfur dioxide 

VOC volatile organic compound 

3.2.2.7. VISUAL RESOURCES MANAGEMENT

Potential air quality impacts would not result directly from visual resources management actions, but 

indirectly from changes in resource use activities on an area of land, and their associated emissions, that 

result from changes in the VRM Class assignment of the area. VRM Class I is the most restrictive and, in 

general, is expected to result in the lowest level of emissions from resource use activities. VRM Classes 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 33 

II, III, and IV are progressively less restrictive. VRM Class IV, in general, is expected to result in the 

highest level of emissions from resource use activities. 

Table 21 of this report presents Visual Resources management impacts in terms of acreage assigned to 

each VRM Class. For the specific management actions included in Alternatives A and E, see the Visual 

Resources section in Chapter 2 of the Proposed RMP. 

Table 21. Land Use Allocations for Visual Resources Management for the SDNM 

VRM Class 

Alternative (BLM Acres) 

A 

(No Action) B C D E (Proposed RMP) 

Class I 158,700 158,700 158,700 457,900 158,700

Class II 91,600 219,000 267,300 28,500 246,500

Class III 116,400 108,700 60,400 None 81,200

Class IV 119,700 0 0 0 0

Source: BLM 2012 

BLM Bureau of Land Management 

RMP Resource Management Plan 

SDNM Sonoran Desert National Monument 

VRM Visual Resource Management 

Table 21 shows that under Alternative E there would be a relatively large increase in VRM Class II 

acreage, a smaller decrease in VRM Class III acreage, and a large decrease in VRM Class IV acreage, 

compared to Alternative A. The net effect of Alternative E would be a shift in acreage from lessrestrictive to more-restrictive VRM classes. This shift is expected to result in lower potential for 

resource use activities that would increase emissions. Land use allocations and activity indicated in 

Table 21 for the entire SDNM are expected to be representative for the portions of the SDNM within 

the NAAs. As a result, because there would be no potential for emissions increases in the NAAs due to 

VRM Class assignments under Alternative E, visual resources management actions in the SDNM do not 

require further conformity evaluation. 

3.2.2.8. WILDLAND FIRE MANAGEMENT

The Proposed RMP indicates that air quality impacts from fire and fuels management would not differ by 

alternative. This suggests that no difference in emissions associated with fire and fuels management 

actions would be expected between Alternative E and Alternative A. Because there would be no 

potential for emissions increases due to fire and fuels management, fire and fuels management actions in 

the SDNM do not require further conformity evaluation. 

3.2.2.9. WILDLIFE AND SPECIAL STATUS SPECIES

BLM manages vegetation and wildlife populations in the Planning Area to ensure high-quality wildlife 

habitat and to protect water resources and watershed conditions. Management actions and other 

activities on acreage managed as wildlife habitat areas generally are subject to greater development 

restrictions resulting in decreased potential for emissions compared to areas not managed as wildlife 

habitat areas. The Air Quality section in Chapter 4 of the Proposed RMP indicates that the air quality 

impacts of Alternative E in the SDNM would be essentially the same as those of Alternative A. 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 34 

Table 22 presents potential habitat management impacts in terms of acreage managed as wildlife habitat 

area. For the specific management actions included in Alternatives A and E, see the Wildlife and Special 

Status Species section in Chapter 2 of the Proposed RMP. 

Table 22. Key Land Use Allocations for Wildlife Habitat for the SDNM 

Wildlife Habitat Area 

Alternative (BLM Acres) 

A 

(No Action) B C D E (Proposed RMP) 

Wildlife Habitat Areas 0 0 0 0 0 

Source: BLM 2012 

BLM Bureau of Land Management 

RMP Resource Management Plan 

SDNM Sonoran Desert National Monument 

Table 22 shows that the number of acres managed as wildlife habitat areas in the SDNM would be zero 

for both Alternative E and Alternative A. This suggests that no difference in emissions associated with 

priority wildlife and habitat management actions would be expected between Alternative E and 

Alternative A. Because there would be no potential for emissions increases due to priority wildlife and 

habitat management with Alternative E, priority wildlife and habitat management actions in the SDNM 

do not require further conformity evaluation. 

4. RESULTS OF THE ANALYSIS

Table 23 summarizes the results of the conformity evaluation for activities under the Proposed RMP 

that are anticipated to cause increased emissions. PM10 emissions include both fugitive and exhaust PM. 

PM2.5 emissions were not quantified because no net emissions increases attributable to the Proposed 

RMP would occur in the West Central Pinal PM2.5 NAA. 

Table 23. Summary of Net Emissions for Conformity Evaluation 

Planning 

Area 

Activity 

Location Description CO NOx SO2 VOC PM10

Construction (tons)

LSDA Buckeye Hills 

East RMZ 

Construct staging areas: five 6-acre and 

one 10-acre, total 40 acres 

25.98 21.52 0.02 2.94 24.79 

 Construct road: 4 miles, 30-foot width 6.07 5.13 0.0046 0.69 3.94 

 Construct trails: 5 miles single-track 0.04 0.01 0.0001 0.001 0.0003

SDNM Anza NHT RMZ Construct pulloffs: 3 acres total 6.20 5.07 0.004 0.71 0.79 

 Improve existing staging areas: two 1.5-

acre areas 

0.09 0.09 0.0002 0.01 0.26 

Total construction 38.38 31.82 0.02 4.36 29.78 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 35 

Table 23. Summary of Net Emissions for Conformity Evaluation 

Planning 

Area 

Activity 

Location Description CO NOx SO2 VOC PM10

Recurring Activities (tons/year)

LSDA Buckeye Hills 

East RMZ 

Increased visitation 2.94 0.40 0.003 0.31 7.37 

 OHV Races 0.84 0.05 0.001 0.54 9.75 

SDNM Anza NHT RMZ Increased visitation 0.42 0.08 0.00 0.01 2.77 

 Increase road maintenance: 12 miles 0.84 0.05 0.00 0.54 9.75 

Total recurring activities 5.45 1.55 .005 1.01 24.92 

Total Emissions and Comparison to Conformity Thresholds 

Sum of construction and recurring emissions (tons, if all activities occur 

in one year) 

43.83 33.37 0.03 5.36 54.70 

Applicable general conformity thresholds (tons/year) 100 100 100 100 70 

CO carbon monoxide 

LSDA Lower Sonoran Decision Area 

NHT National Historic Trail 

NOx nitrogen oxides 

OHV Off-highway vehicle 

PM particulate matter 

RMZ Recreation Management Zone 

SDNM Sonoran Desert National Monument 

SO2 sulfur dioxide 

VOC volatile organic compound 

The “Total construction” sum represents the one-time emissions that would occur if all actions were 

completed in one year, which is a conservative assumption (represents a worst-case scenario). As 

indicated in Table 23, total construction emissions would be less than the applicable conformity 

thresholds for all applicable criteria pollutants. The “Total recurring activities” sum, which represents 

annual emissions, is also less than the conformity thresholds. The “Sum of construction and recurring 

emissions” in Table 23 represents the emissions that would occur if all projects were completed 

simultaneously and visitation increased immediately to the projected levels, which represents a worstcase scenario, and demonstrates that net emissions would be less than the conformity thresholds. 

Appendix A provides further detail on the emissions estimates developed for the conformity analysis. 

5. CONCLUSION

The general conformity evaluation performed for the Proposed RMP/Final EIS demonstrates that the net 

emissions increases attributable to the Proposed RMP (Alternative E) compared to Alternative A (No 

Action) would be less than the general conformity de minimis thresholds, even under a worst-case 

scenario. Accordingly, the Proposed RMP conforms to the applicable SIPs. As a result, no further 

conformity evaluation is necessary and a conformity determination is not required. 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation 36 

6. REFERENCES

ADEQ (Arizona Department of Environmental Quality). 2002a. Ajo Sulfur Dioxide Nonattainment Area 

State Implementation and Maintenance Plan. Available online: 

http://www.azdeq.gov/function/forms/docs.html#air

ADEQ (Arizona Department of Environmental Quality). 2002b. Miami Sulfur Dioxide Nonattainment 

Area State Implementation and Maintenance Plan. Available online: 

http://www.azdeq.gov/function/forms/docs.html#air

ADEQ (Arizona Department of Environmental Quality). 2008. Miami Moderate Area PM10 Limited 

Maintenance Plan and Request for Redesignation to Attainment. Available online: 

http://www.azdeq.gov/environ/air/plan/download/miamipm10.pdf

ADEQ (Arizona Department of Environmental Quality). 2011. Ajo PM10 Limited Maintenance Plan and 

Request for Redesignation. Available online: http://www.azdeq.gov/environ/air/plan/notmeet.html#ajo

BLM (Bureau of Land Management). 2012. Lower Sonoran and Sonoran Desert National Monument 

Proposed Resource Management Plan and Final Environmental Impact Statement. 

EPA (U.S. Environmental Protection Agency). 1995. Compilation of Air Pollutant Emission Factors, 

Volume I: Stationary Point and Area Sources, Fifth Edition. Section 13.2, Fugitive Dust Sources. 

Available online: http://www.epa.gov/ttn/chief/ap42/ch13/index.html

EPA (U.S. Environmental Protection Agency). 2008. NONROAD Model (nonroad engines, equipment, 

and vehicles). Available online: http://www.epa.gov/otaq/nonrdmdl.htm#model

EPA (U.S. Environmental Protection Agency). 2010. MOVES2010a (Motor Vehicle Emission Simulator). 

Available online: http://www.epa.gov/otaq/models/moves/index.htm

Goossens, D., Buck, B. 2009. Dust emission by off-road driving: Experiments on 17 arid soil types, 

Nevada, USA. Geomorphology 107:118-138 (2009). Available online: 

http://azstateparks.com/ohv/downloads/OHV_Dust_Emission_17.pdf

MAG (Maricopa Association of Governments). 2003. Carbon Monoxide Redesignation Request and 

Maintenance Plan for the Maricopa County Nonattainment Area. Available online: 

http://www.azmag.gov/addons/MAG/download.asp?ID=5260

MAG (Maricopa Association of Governments). 2007a. Eight-Hour Ozone Plan for the Maricopa 

Nonattainment Area. Available online: http://www.azmag.gov/Documents/ES_2007_8-

HourOzonePlan.pdf

MAG (Maricopa Association of Governments). 2007b. MAG 2007 Five Percent Plan for PM-10 for the 

Maricopa County Non-attainment Area. Available online: 

http://www.azmag.gov/Documents/pdf/cms.resource/PM10_2007_Main-Plan.pdf

PAQCD (Pinal County Air Quality Control District). In preparation. West Central Pinal County State 

Implementation Plan. Available online: 

http://pinalcountyaz.gov/Departments/AirQuality/Pages/OtherEPARegulatoryActions.aspx
Appendix A 

Emissions Estimates 

A
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation A-i 

TABLE OF CONTENTS

1. Pad Construction – Dust.................................................................................................................. A‐1

2. Onsite Exhaust................................................................................................................................. A‐2

3. Traffic – Construction Dust ............................................................................................................. A‐3

4. Traffic – Recreational Dust.............................................................................................................. A‐7

5. Traffic – Dust Paved ........................................................................................................................ A‐8

6. Traffic – Exhaust.............................................................................................................................. A‐9

7. Site Preparation/Staging Areas – Lower Sonoran Decision Area.................................................. A‐11

8. Gravel Road and Trail Construction .............................................................................................. A‐17

9. Gravel and Hardening – Sonoran Desert National Monument..................................................... A‐24

10. Usage – Lower Sonoran Decision Area ......................................................................................... A‐30

11. Usage – Sonoran Desert National Monument.............................................................................. A‐32

12. Off‐highway Vehicle Races............................................................................................................ A‐35
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement 

April 2012 Air Quality General Conformity Evaluation A-ii 

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Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 1. Pad Construction – Dust 

Inputs for On-Site Dust Computations Local Construction (per acre) 

1 week to build 3.64 acres 

days acres 

5 3.64 1.373626374 days/acre road 

4 days/acre area 

Construction Activity TSP Emission 

Factor1

Construction Activity 

Duration2

Factor for 10 hr days 

vs 12 hr days 

Emission Control 

Efficiency 

TSP Emissions 

(Controlled) 

(tons/acre-month) 

(tons/acre-30days) days/acre 10 (%) T/acre2 

1.2 1.37 0.833 50 0.02 1.2 4.00 0.833 50 0.07 

1 EPA AP-42, Section 13.2.3, "Heavy Construction Operations"; TSP = total suspended particulates (12 hour day). 2 5 days/3.64 acres = 0.0669 months/acre 1.3763 days/acre, assuming 10 hour days. 3 EPA AP-42, Section 13.2.2 "Unpaved Roads", Background Document. Assuming that 36% of the TSP is in the PM10 size range, monthly emissions converted 

based on 30-day month. 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 2. Onsite Exhaust 

Inputs for Onsite 

Site/Pad Construction – Heavy Equipment Exhaust Emissions 

Heavy 

Equipment 

Engine 

Horsepower 

(hp) 

Number 

Required 

Operating 

Load 

Factor1

Pollutant Emission Factor2

(g/hp-hr) 

Pollutant Emissions 

(g/hr) 

P

CO 

NO

x

SO

2

VOC 

PM10

CO 

NO

x

SO

2

VOC 

PM10

CO 

NO

x

Backhoe 100 1 1 8.5 6.9 0.0047 0.97 0.4 850 690 0.47 97 40 0.0009361 0.000759Roller 100 1 1 8.5 6.9 0.0047 0.97 0.4 850 690 0.47 97 40 0.0009361 0.000759Scraper 600 1 1 8.5 6.9 0.0047 0.97 0.4 5100 4140 2.82 582 240 0.0056167 0.004559Grader 300 1 1 8.5 6.9 0.0047 0.97 0.4 2550 2070 1.41 291 120 0.0028084 0.002279

Total Heavy Equipment Tailpipe Emissions 0.0102974 0.008359

Four days assumes a 12 hours day 1Assumed to be 1 because no data available (conservative). 2 Emission factors based on the fact that there is a mix of Tier 0, 1 and 2 equipment operating in the field. Therefore, Tier 1 emission factors are conservatively assumed 

SO2 emissions based on a sulfur balance and 15 ppm diesel fuel. 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 3. Traffic – Construction Dust 

Fugitive Dust from Heavy Equipment on Industrial Unpaved Roads (1a) 

Emission Factors for Industrial Unpaved Roads 1

Parameter PM10 PM2.5

E (lb/VMT)1a = k (s/12)a (W/3)b k 1.5 0.15 

a 0.9 0.9 

b 0.45 0.45 

Function/Variable Description Assumed Value Reference 

E = size-specific emission factor (lb/VMT) S = surface material silt content (%) varies EPA AP-42 Section 13.2.2, Table 13.W = mean vehicle weight (tons) Listed in the table below M = surface material moisture content (%) 2.0 EPA AP-42 Section 13.2.2 1 Source: EPA, AP-42 Volume I, Section 13.2.2 Unpaved Roads, Table 13.2.2-2, Nov. 2006 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Fugitive Dust from Commuting Vehicles on Unpaved Roads (1b)

Emission Factors for Publicly Accessible Unpaved Roads1

Parameter PM10 PM2.5

E (lb/VMT)1b = k (s/12)a (S/30)d _ C k 1.8 0.18 (M/0.5)c a 1 1 

d 0.5 0.5 

Eext = E (1 - P/365) c 0.2 0.2 

Function/Variable Description Assumed Value Reference 

E = size-specific emission factor (lb/VMT) Eext = size-specific emission factor extrapolated for natural 

mitigation (lb/VMT) 

s = surface material silt content (%) varies EPA AP-42 Section 13.2.2, Table 13.2.2-1 S = mean vehicle speed (mph) C = emission factor for 1980's vehicle fleet exhaust, brake wear, and tire wear (lb/VMT) 

PM2.5 0.0004 EPA AP-42 Section 13.2.2, Table 13.2.2-4 

PM10 0.0005 EPA AP-42 Section 13.2.2, Table 13.2.2-4 

M = surface material moisture content (%) 2.0 EPA AP-42 Section 13.2.2 P = Number of days precip per year 36 http://lwf.ncdc.noaa.gov/oa/climate/online/ccd/CE = control efficiency of watering 2 50% 1 Source: EPA, AP-42 Volume I, Section 13.2.2 Unpaved Roads, Table 13.2.2-2, Nov. 2006 2 Fitzpatrick, M. 1990. User's Guide: Emission Control Technologies and Emission Factors for Unpaved Road Fugitive Emissions, 

EPA/625/5-87/022. http://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=20008SFC. 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Construction Vehicle Traffic Dust Emissions 

Vehicle 

Type 

Road 

Type

Dust 

Control 

Method1

Average 

Vehicle 

Weight 

(lb)

Average 

Vehicle 

Speed 

(mph)

Silt 

Content2

(%)

Moisture 

Content3

(%)

Vehicle Activity Data (Site-specific) 

Emission 

Control 

Efficiency5

(%)

P

Em

Fa

(lb/

Vehicle

Count 

Round 

Trips 

(RTs) 

(RT/pad)

RT 

Distance 

(miles)

Vehicle 

Miles 

Traveled 

(VMT)4

(VMT/pad)

Pickup, car, minivan, SUV (average)8

Local Chemical 5,000 35 10.95 2.4 1 1 1 1 85 1

Resource Water 5,000 20 10.95 2.4 1 1 1 1 50 1

Light Trucks - pick-up/tool Local Chemical 7,000 35 10.95 2.4 1 1 1 1 85 1

Resource Water 7,000 20 10.95 2.4 1 1 1 1 50 1

Shuttle-bus Local Chemical 10,000 35 10.95 2.4 1 1 1 1 85 1

Resource Water 10,000 20 10.95 2.4 1 1 1 1 50 1

Dump w/ bellydump Local Chemical 70,000 35 10.95 2.4 1 1 1 1 85 1

Resource Water 70,000 20 10.95 2.4 1 1 1 1 50 4

5-ton stake bed Local Chemical 10,000 35 10.95 2.4 1 1 1 1 85 1

Resource Water 10,000 20 10.95 2.4 1 1 1 1 50 1

Flatbed w/crane Local Chemical 35,000 35 10.95 2.4 1 1 1 1 85 1

Resource Water 35,000 20 10.95 2.4 1 1 1 1 50 3

Concrete Truck (average)9

Local Chemical 42,000 35 10.95 2.4 1 1 1 1 85 1

Resource Water 42,000 20 10.95 2.4 1 1 1 1 50 3

Heavy Truck (Water) Local Chemical 35,000 35 10.95 2.4 1 1 1 1 85 1

Resource Water 35,000 20 10.95 2.4 1 1 1 1 50 3
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Construction Vehicle Traffic Dust Emissions 

Vehicle 

Type 

Road 

Type

Dust 

Control 

Method1

Average 

Vehicle 

Weight 

(lb)

Average 

Vehicle 

Speed 

(mph)

Silt 

Content2

(%)

Moisture 

Content3

(%)

Vehicle Activity Data (Site-specific) 

Emission 

Control 

Efficiency5

(%)

P

Em

Fa

(lb/

Vehicle

Count 

Round 

Trips 

(RTs) 

(RT/pad)

RT 

Distance 

(miles)

Vehicle 

Miles 

Traveled 

(VMT)4

(VMT/pad)

Rig Haul Trucks 

Local Road Chemical 80,000 35 10.95 2.4 1 1 1 1 85 1Resource Road Water 80,000 20 10.95 2.4 1 1 1 1 50 4

Total Unpaved Road Tra

1 Dust control methods include using water (resource road) or chemical (local road) as a dust suppressant along with vehicle restriction speed limit of 25 mph 2 Silt content - used 10.95% for all 3 EPA AP-42, Table 11.9-3, "Typical Values for Correction Factors Applicable to the Predictive Emission Factor Equations." 4 Calculated as Round Trips per Vehicle Type x Round Trip Distance. (Assume 4 miles local roads, 2 miles industrial) 5 EPA AP-42, Figure 13.2.2-2, "Watering control effectiveness for unpaved travel surfaces.", Fugitive Dust Handbook, Western Regional Air Partnership 2006, Chapter 6 EPA AP-42, Section 13.2.2 "Unpaved Roads", equations 1a and 1b 7 Calculated as lb/VMT x VMT/pad x control efficiency 8 Average assumed for car/minivan/SUV/pickup = 5,000 lb 9 Concrete truck - empty 26,000. Concrete 4,000/yd, 8 yd max. Average, 42,000 lbs 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 4. Traffic – Recreational Dust 

Recreational Use Dust Formulas 

Vehicle Type Road Type Dust Control Method1

Average 

Vehicle 

Weight2

(lb)

Average 

Vehicle 

Speed 2

(mph)

Silt 

Content3

(%)

Moisture 

Content4

(%)

Vehicle

Count 

Round 

Trips 

(RTs) 

(RT/pad)

RT 

Distance 

(miles)

Vehicle 

Miles 

Traveled 

(VMT)5

(VMT/pad)

Emission 

Control 

Efficiency6

(%)

(

Primary Unpaved Local Chemical/water 4,311 36.75 10.95 2.4 1 1 1 1 50 Secondary Unpaved Local Water 4,336 19.25 10.95 2.4 1 1 1 1 0 Jeep Road Local Water 3,097 9 10.95 2.4 1 1 1 1 0 ATV Road Local Water 694 8 10.95 2.4 1 1 1 1 0 Motorcycle Trail Local Water 470 10 10.95 2.4 1 1 1 1 0 

Total Unpaved Road T

equation 1b - commuting vehicles on unpaved roads 1 Dust control methods include using water (resource road) or chemical (local road) as a dust suppressants 2 Weighted average for vehicle weight* * EPA Dust formula assumptions rev0 – LSFO.xls 

Weight Speed 

Primary Unpaved 4311 lbs 36.75 Secondary Unpaved 4336 lbs 19.25 (Jeep road) 3097 lbs 9 (ATV trail) 694 lbs 8 (Motorcycle trail) 470 lbs 10 3 Weighted silt content - used 10.95% for all 4 EPA AP-42, Table 11.9-3, "Typical Values for Correction Factors Applicable to the Predictive Emission Factor Equations." 5 Calculated as Round Trips per Vehicle Type x Round Trip Distance. (Assume 4 miles local roads, 2 miles industrial) 6 EPA AP-42, Figure 13.2.2-2, "Watering control effectiveness for unpaved travel surfaces.", Fugitive Dust Handbook, Western Regional Air Partnership 2006, Chapter 6 7 EPA AP-42, Section 13.2.2 "Unpaved Roads", equations 1a and 1b. Calculated as lb/VMT x VMT/pad x control efficiency 8 Calculated as lb/VMT x VMT/pad x control efficiency 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 5. Traffic – Dust Paved 

Area Construction Traffic 

E = k (sL)0.91 (w)1.02 Equation source: AP-42 sec. 13.2.3, equation 1 Function/Variable Description E = emission factor in grams/vehicle-mile of travel k = particle size multiplier for PM10 in lb/VMT sL = surface loading in grams per meter squared W= average vehicle weight I tons  Values for PM10k (lb/VMT) 0.0022 for PM10sL (g/m2) 0.2 for ADT of 500-5,000 

Vehicle Type 

Average Vehicle 

Weight 

(lb) 

sL 

(%) 

PM10 Emission 

Factor 

(lb/VMT) 

Pickup, car, minivan, SUV (average)1 5,000 0.2 0.0015 Light Trucks - pick-up/tool 7,000 0.2 0.0023 Shuttle-bus 10,000 0.2 0.0035 Dump w/ bellydump 70,000 0.2 0.0362 5-ton stake bed 10,000 0.2 0.0035 Flatbed w/crane 35,000 0.2 0.0158 Concrete Truck (average)2 42,000 0.2 0.0196 Heavy Truck (Water) 35,000 0.2 0.0158 Rig Haul Trucks 80,000 0.2 0.0425 1 Average assumed for car/minivan/SUV/pickup=5,000 lbs 2 Concrete truck - empty 26,000. Concrete 4,000/yd, 8 yd max. Average, 42,000 lbs 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 6. Traffic – Exhaust 

Emission Factors for Commuting Vehicles – MOVES 

Emission Factors (gm/mile) 

Project Year 2013 NOx PM10 SO2 CO Rural Restricted - LSDA Passenger Car/Truck - Gas 0.72 0.01 0.006 4.89 Passenger Car 0.41 0.01 0.005 3.22 Passenger Truck 1.04 0.02 0.007 6.56 Motorcycle 0.77 0.03 0.006 11.83 Light Commercial Truck - Diesel 2.53 0.16 0.005 1.45 School Bus/ (Shuttle Bus) - Diesel 7.36 0.35 0.009 1.72 Single Unit Long/Short Haul Truck - diesel 2.88 0.15 0.006 0.94 Combination Long/Short Haul Truck (gravel/equipment delivery) - diesel 9.01 0.38 0.015 1.74 Rural Unrestricted - SDNM - and trails in LSDA Passenger Car/Truck - Gas 0.62 0.02 0.006 3.20 Passenger Car 0.35 0.02 0.005 1.98 Passenger Truck 0.90 0.02 0.006 4.42 Motorcycle 0.75 0.03 0.005 11.81 Light Commercial Truck - Diesel 2.84 0.18 0.005 1.93 School Bus/ (Shuttle Bus) - Diesel 5.39 0.37 0.006 1.72 Single Unit Long/Short Haul Truck - diesel 5.39 0.37 0.006 1.72 Combination Long/Short Haul Truck (gravel/equipment delivery) - diesel 9.04 0.48 0.015 2.15 Source: EPA NONROAD model, 2008 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Emission Factors for Off-Road ATV 

Vehicle Type Emission Factors (g/mi) Class NOx PM10 PM2.5 SOx CO VOC 

2-Stroke ATV R12S 0.25 1.86 1.71 0.03 47.81 48.72 Source: EPA NONROAD model, 2008 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 7. Site Preparation/Staging Areas – Lower Sonoran Decision Area 

Pad Construction – Dust 

On-site Emissions - Onsite Heavy Equipment – Dust 

Area 

Size 

(acres) 

Number 

of Sites 

Operation 

(%) 

TSP 

Emissions 

(Controlled) 

T/acre2

PM10

Emissions 

(controlled) 

T/acre2

TSP 

Emissions 

(Controlled) 

T/acre2

LSDA - Large Staging Area 13.64 1 100 0.07 0.02 12.40 LSDA - Small Staging Area 9.64 5 100 0.07 0.02 30.98 

Total: 43.3

Onsite Exhaust 

Tail Pipe Emissions – Onsite Heavy Equipment

Pollutant Emissions (T/hr)

CO 

NO

x

SO

2

VOC 

PM10

Total Heavy Equipment Tailpipe Emissions 0.0103 0.0084 0.0000 0.0012 0.0005 

T/

Area 

Size 

(acres) 

Number of 

Sites 

Operation 

(%) Hours/acre1 Hours 

CO 

NO

x

LSDA - Large Staging Area 13.64 1 100 40 545.6 5.62 4.561 0.LSDA - Small Staging Area 9.64 5 100 40 1928 19.85 16.116 0.

Total: 25.47 20.677 0.

1 Each Piece of equipment needs 10 hours /acre and there are 4 of them 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Traffic – Dust – Large Staging Area

Vehicle Type 

Road 

Type 

Dust 

Control 

Method 

Vehicle

Count Vehicles/site 

RT 

Distance 

Vehicle Miles 

Traveled (VMT)1

PM10

Emissions

(controlled) 

PM2.5

Emissions

(controlled) 

Not 

used 

(RT/staging 

areas) (miles) (VMT/all staging areas) (lb/VMT) (lb/VMT) 

Commuter Vehicle Local Chemical 1 273 4 1091 0.19 0.02 

Resource Water 1 273 2 546 0.64 0.06 

Light Trucks - pick-up/tool Local Chemical 1 55 4 218 0.19 0.02 

Resource Water 1 55 2 109 0.74 0.07 

Shuttle-bus Local Chemical 1 55 4 218 0.19 0.02 

Resource Water 1 55 2 109 0.87 0.09 

Dump w/ bellydump Local Chemical 1 252 4 1008 0.19 0.02 

Resource Water 1 252 2 504 2.09 0.21 

5-ton stake bed Local Chemical 1 2 4 8 0.19 0.02 

Resource Water 1 2 2 4 0.87 0.09 

Flatbed w/crane Local Chemical 1 1 4 4 0.19 0.02 

Resource Water 1 1 2 2 1.53 0.15 

Concrete Truck Local Chemical 1 3 4 11 0.19 0.02 

Resource Water 1 3 2 5 1.66 0.17 

Water Truck Local Chemical 1 55 4 218 0.19 0.02 

Resource Water 1 218 2 436 1.53 0.15 

Rig Haul Trucks Local Chemical 1 8 4 32 0.19 0.02 

Resource Water 1 8 2 16 2.22 0.22 

Total (tons): Tons - Large: 

1 VMT = vehicles per site *round trip distance over all site prep areas 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Traffic – Dust – Small Staging Area

Vehicle Type Road Type 

Dust 

Control 

Method 

Vehicle

Count Vehicles/site RT Distance Vehicle Miles Traveled (VMT)1 PM10 Emissions (controlled) PM2.5 Emissions (controlled) 

Not 

used 

(RT/staging 

areas) (miles) (VMT/all staging areas) (lb/VMT) (lb/VMT) 

Commuter Vehicle Local Chemical 1 964 4 3856 0.19 0.02 

Resource Water 1 964 2 1928 0.64 0.06 

Light Trucks - pick-up/tool Local Chemical 1 193 4 771 0.19 0.02 

Resource Water 1 193 2 386 0.74 0.07 

Shuttle-bus Local Chemical 1 193 4 771 0.19 0.02 

Resource Water 1 193 2 386 0.87 0.09 

Dump w/ bellydump Local Chemical 1 997 4 3986 0.19 0.02 

Resource Water 1 997 2 1993 2.09 0.21 

5-ton stake bed Local Chemical 1 7 4 29 0.19 0.02 

Resource Water 1 7 2 14 0.87 0.09 

Flatbed w/crane Local Chemical 1 5 4 20 0.19 0.02 

Resource Water 1 5 2 10 1.53 0.15 

Concrete Truck Local Chemical 1 10 4 39 0.19 0.02 

Resource Water 1 10 2 19 1.66 0.17 

Water Truck Local Chemical 1 193 4 771 0.19 0.02 

Resource Water 1 771 2 1542 1.53 0.15 

Rig Haul Trucks Local Chemical 1 40 4 160 0.19 0.02 

Resource Water 1 40 2 80 2.22 0.22 

 Tons - Small (all): 1 VMT = vehicles per site *round trip distance over all site prep areas 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Traffic – Dust – Paved

Total truck trips calculated above miles = 50-6 for un

Vehicle Type 

Vehicle

Count Vehicles/site RT Distance Vehicle Miles Traveled (VMT)1 PM10 Emissions (controlled) PM2.5 Emissions (controlled) 

Not 

used 

(RT/staging 

areas) (miles) (VMT/all staging areas) (lb/VMT) (lb/VMT) 

Large Staging Commuter Vehicle 1 273 44 12003 0.0015 0.0004 Small Staging 1 964 44 42416 0.0015 0.0004 Large Staging Light Trucks - pick-up/tool 1 55 44 2401 0.0023 0.0006 Small Staging 1 193 44 8483 0.0023 0.0006 Large Staging Shuttle-bus 1 55 44 2401 0.0035 0.0009 Small Staging 1 193 44 8483 0.0035 0.0009 Large Staging Dump w/ bellydump 1 252 44 11093 0.0362 0.0089 Small Staging 1 997 44 43850 0.0362 0.0089 Large Staging 5-ton stake bed 1 2 44 90 0.0035 0.0009 Small Staging 1 7 44 318 0.0035 0.0009 Large Staging Flatbed w/crane 1 1 44 44 0.0158 0.0039 Small Staging 1 5 44 220 0.0158 0.0039 Large Staging Concrete Truck 1 3 44 120 0.0196 0.0048 Small Staging 1 10 44 424 0.0196 0.0048 Large Staging Water Truck 1 55 44 2401 0.0158 0.0039 Small Staging 1 193 44 8483 0.0158 0.0039 Large Staging Rig Haul Trucks 1 8 44 352 0.0425 0.0104 Small Staging 1 40 44 1760 0.0425 0.0104 

lbs - large: 

lbs - small: 

Tons - large area: 

Tons - small areas: 

1 VMT = vehicles per site *round trip distance over all site prep areas 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Tail Pipe Emissions – Transient vehicles

Vehicle Type Type 

Vehicles/site 

RT 

Distance 

Vehicle Miles 

Traveled (VMT)1

CO 

NO

x

SO

2

VOC 

PM10

CO 

(RT/all 

staging areas) (miles) (VMT /all staging areas) 

g/mile l

Large Staging Commuter Vehicle Gas Car/Truck 273 50 13640 4.89 0.72 0.006 0.10 0.01 146.80 Small Staging 964 50 48200 4.89 0.72 0.006 0.10 0.01 518.75 Large Staging Light Trucks - pick- up/tool Diesel 55 50 2728 1.45 2.53 0.005 0.26 0.16 8.70 Small Staging 193 50 9640 1.45 2.53 0.005 0.26 0.16 30.75 Large Staging Shuttle-bus Diesel 55 50 2728 1.72 7.36 0.009 0.35 0.35 10.31 Small Staging 193 50 9640 1.72 7.36 0.009 0.35 0.35 36.44 Large Staging Dump w/ bellydump Diesel - Combo 252 50 12606 1.74 9.01 0.015 0.28 0.38 48.20 2Small Staging 997 50 49830 1.74 9.01 0.015 0.28 0.38 190.53 9Large Staging 5-ton stake bed Diesel 2 50 102 0.94 2.88 0.006 0.22 0.15 0.21 Small Staging 7 50 362 0.94 2.88 0.006 0.22 0.15 0.75 Large Staging Flatbed w/crane Diesel 1 50 50 0.94 2.88 0.006 0.22 0.15 0.10 Small Staging 5 50 250 0.94 2.88 0.006 0.22 0.15 0.52 Large Staging Concrete Truck Diesel 3 50 136 0.94 2.88 0.006 0.22 0.15 0.28 Small Staging 10 50 482 0.94 2.88 0.006 0.22 0.15 1.00 Large Staging Water Truck Diesel 55 50 2728 0.94 2.88 0.006 0.22 0.15 5.66 Small Staging 193 2 386 0.94 2.88 0.006 0.22 0.15 0.80 Large Staging Rig Haul Trucks Diesel - Combo 8 50 400 1.74 9.01 0.015 0.28 0.38 1.53 Small Staging 40 50 2000 1.74 9.01 0.015 0.28 0.38 7.65 

RT/all staging 

area 

hours idle 

per each RT hours g/hr 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Tail Pipe Emissions – Transient vehicles

Vehicle Type Type 

Vehicles/site 

RT 

Distance 

Vehicle Miles 

Traveled (VMT)1

CO 

NO

x

SO

2

VOC 

PM10

CO 

(RT/all 

staging areas) (miles) (VMT /all staging areas) 

g/mile l

Large Staging Dump w/belly dump - idle hours2 Diesel 252 0.25 63 0.09 5.87 5.97 2.93 3.37 0.01 Small Staging Dump w/belly dump - idle hours2 Diesel 997 0.25 249 0.09 5.87 5.97 2.93 3.37 0.05 

Tons Large staging 

areas: 

0.11 

Tons/small staging 

areas: 

0.39 

1 VMT = vehicles per site * round trip distance over all site prep areas

2 Idle assumed 15 minutes/trip 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 8. Gravel Road and Trail Construction 

Pad Construction – Dust 

On-site Emissions – Onsite Heavy Equipment – Dust 

Area Length Width Size Number of Sites Operation TSP Emissions (Controlled) PM10 Emissions (controlled) TS

Emiss

(Contr

(miles) (ft) (acres) (%) T/acre2 T/acre2 T/ac

LSDA - Road 4 30 14.55 1 100 0.02 0.01 4.8SNDM - Pull Off 3.00 1 100 0.02 0.01 0.2

Onsite Exhaust – Tail Pipe Emissions – Onsite Heavy Equipment

Pollutant Emissions (T/hr) 

CO 

NO

x

SO

2

VOC 

PM10

Total Heavy Equipment Tailpipe Emissions 0.010297 0.008359 0.000006 0.001175 0.000485 

T/area 

Area Size 

Number 

of Sites Operation Hours/acre1 Hours 

CO 

NO

x

SO

2

(acres) (%) 

LSDA - Road 14.55 1 100 40 581.8 5.99 4.86 0.0033 SNDM - Pull Off 3.00 5 100 40 600 6.18 5.02 0.0034 

Total: 12.17 9.88 0.0067 

1 Each Piece of equipment needs 10 hours /acre and there are 4 of them 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Traffic – Dust – Lower Sonoran Decision Area Road

Vehicle Type Road Type 

Dust 

Control 

Method 

Vehicle

Count Vehicles/site RT Distance Vehicle Miles Traveled (VMT)1 PM10 Emissions (controlled) 

Em

(co

Not 

used 

(RT/staging 

areas) (miles) (VMT/all staging areas) (lb/VMT) (l

Commuter Vehicle Local Chemical 1 100 4 400 0.19 

Resource Water 1 100 2 200 0.64 

Light Trucks - pick-up/tool Local Chemical 1 20 4 80 0.19 

Resource Water 1 20 2 40 0.74 

Shuttle-bus Local Chemical 1 20 4 80 0.19 

Resource Water 1 20 2 40 0.87 

Dump w/ bellydump Local Chemical 1 480 4 1920 0.19 

Resource Water 1 480 2 960 2.09 

5-ton stake bed Local Chemical 1 2 4 9 0.19 

Resource Water 1 2 2 4 0.87 

Flatbed w/crane Local Chemical 1 1 4 4 0.19 

Resource Water 1 1 2 2 1.53 

Concrete Truck Local Chemical 1 3 4 12 0.19 

Resource Water 1 3 2 6 1.66 

Water Truck Local Chemical 1 20 4 80 0.19 

Resource Water 1 80 2 160 1.53 

Rig Haul Trucks Local Chemical 1 8 4 32 0.19 

Resource Water 1 8 2 16 2.22 

To

Assume the 4 miles of road construct are the local road mile and 1 each way for resource.1 VMT = vehicles per site * round trip distance over all site prep areas 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Traffic – Dust – Sonoran Desert National Monument Pulloffs

Vehicle Type Road Type 

Dust 

Control 

Method 

Vehicle

Count Vehicles/site RT Distance Vehicle Miles Traveled (VMT)1 PM10 Emissions (controlled) 

Em

(co

Not 

used 

(RT/staging 

areas) (miles) (VMT/all staging areas) (lb/VMT) (l

Commuter Vehicle Local Chemical 1 21 4 82 0.19 

Resource Water 1 21 2 41 0.64 

Light Trucks – pick-up/tool Local Chemical 1 4 4 16 0.19 

Resource Water 1 4 2 8 0.74 

Shuttle-bus Local Chemical 1 4 4 16 0.19 

Resource Water 1 4 2 8 0.87 

Dump w/ bellydump Local Chemical 1 99 4 396 0.19 

Resource Water 1 99 2 198 2.09 

5-ton stake bed Local Chemical 1 0.5 4 2 0.19 

Resource Water 1 0.5 2 1 0.87 

Flatbed w/crane Local Chemical 1 1 4 4 0.19 

Resource Water 1 1 2 2 1.53 

Concrete Truck Local Chemical 1 1 4 2 0.19 

Resource Water 1 1 2 1 1.66 

Water Truck Local Chemical 1 4 4 16 0.19 

Resource Water 1 16 2 33 1.53 

Rig Haul Trucks Local Chemical 1 8 4 32 0.19 

Resource Water 1 8 2 16 2.22 

Ton

1 VMT = vehicles per site * round trip distance over all site prep areas 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Traffic – Dust – Paved

Vehicle Type 

Vehicle

Count Vehicles/site 

RT 

Distance 

Vehicle Miles 

Traveled (VMT)1

PM10

Emissions

(controlled) 

Em

(co

Not 

used 

(RT/staging 

areas) (miles) (VMT/all staging areas) (lb/VMT) (lb

LSDA Road Commuter Vehicle 1 100 44 4396 0.0015 0SDNM Pulloff 1 21 44 907 0.0015 0LSDA Road Light Trucks – pick-up/tool 1 20 44 879 0.0023 0SDNM Pulloff 1 4 44 181 0.0023 0LSDA Road Shuttle-bus 1 20 44 879 0.0035 0SDNM Pulloff 1 4 44 181 0.0035 0LSDA Road Dump w/ bellydump 1 480 44 21120 0.0362 0SDNM Pulloff 1 99 44 4356 0.0362 0LSDA Road 5-ton stake bed 1 2 44 96 0.0035 0SDNM Pulloff 1 0.5 44 20 0.0035 0LSDA Road Flatbed w/crane 1 1 44 44 0.0158 0SDNM Pulloff 1 1 44 44 0.0158 0LSDA Road Concrete Truck 1 3 44 128 0.0196 0SDNM Pulloff 1 1 44 26 0.0196 0LSDA Road Water Truck 1 20 44 879 0.0158 0SDNM Pulloff 1 4 44 181 0.0158 0LSDA Road Rig Haul Trucks 1 8 44 352 0.0425 0SDNM Pulloff 1 8 44 352 0.0425 0

Lb

Lbs 

Ton

Ton

1 VMT = vehicles per site * round trip distance over all site prep areas 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Traffic – Exhaust - Tail Pipe Emissions - Transient vehicles

Vehicle 

Type Type 

Vehicles/site 

RT 

Distance 

Vehicle Miles 

Traveled 

(VMT)1

CO 

NO

x

SO

2

VOC 

PM10

CO 

NO

x

(RT/all staging 

areas) (miles) (VMT /all staging areas) 

g/mile 

LSDA - (Rural Restricted) Commuter 

Vehicle 

Gas 

Car/Truck 100 50 4995 4.89 0.72 0.01 0.10 0.01 53.76 7.9

SDNM - (Rural Unrestricted) 21 50 1030 3.20 0.62 0.01 0.10 0.02 7.26 1.4LSDA - (Rural Restricted) Light Trucks - 

pick-up/tool 

Diesel 20 50 999 1.45 2.53 0.00 0.26 0.16 3.19 5.5

SDNM - (Rural Unrestricted) 4 50 206 1.93 2.84 0.00 0.37 0.18 0.88 1.2LSDA - (Rural Restricted) Shuttle-bus Diesel 20 50 999 1.72 7.36 0.01 0.35 0.35 3.78 16.SDNM - (Rural Unrestricted) 4 50 206 1.72 5.39 0.01 0.42 0.37 0.78 2.4LSDA - (Rural Restricted) Dump w/ 

bellydump 

Diesel - 

Combo 480 50 24000 1.74 9.01 0.01 0.28 0.38 91.77 476.

SDNM - (Rural Unrestricted) 99 50 4950 2.15 9.04 0.01 0.37 0.48 23.49 98.6LSDA - (Rural Restricted) 5-ton stake 

bed 

Diesel 2 50 109 0.94 2.88 0.01 0.22 0.15 0.23 0.6

SDNM - (Rural Unrestricted) 0 50 23 1.72 5.39 0.01 0.42 0.37 0.09 0.2LSDA - (Rural Restricted) Flatbed 

w/crane 

Diesel 1 50 50 0.94 2.88 0.01 0.22 0.15 0.10 0.3

SDNM - (Rural Unrestricted) 1 50 50 1.72 5.39 0.01 0.42 0.37 0.19 0.5LSDA - (Rural Restricted) Concrete 

Truck 

Diesel 3 50 145 0.94 2.88 0.01 0.22 0.15 0.30 0.9

SDNM - (Rural Unrestricted) 1 50 30 1.72 5.39 0.01 0.42 0.37 0.11 0.3
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Traffic – Exhaust - Tail Pipe Emissions - Transient vehicles

Vehicle 

Type Type 

Vehicles/site 

RT 

Distance 

Vehicle Miles 

Traveled 

(VMT)1

CO 

NO

x

SO

2

VOC 

PM10

CO 

NO

x

(RT/all staging 

areas) (miles) (VMT /all staging areas) 

g/mile 

LSDA - (Rural Restricted) Water Truck Diesel 20 50 999 0.94 2.88 0.01 0.22 0.15 2.07 6.3LSDA - (Rural Restricted) 80 2 160 0.94 2.88 0.01 0.22 0.15 0.33 1.0SDNM - (Rural Unrestricted) Water Truck Diesel 4 50 206 1.72 5.39 0.01 0.42 0.37 0.78 2.4SDNM - (Rural Unrestricted) 16 2 33 1.72 5.39 0.01 0.42 0.37 0.12 0.3LSDA - (Rural Restricted) Rig Haul 

Trucks 

Diesel - 

Combo 8 50 400 1.74 9.01 0.01 0.28 0.38 1.53 7.9

SDNM - (Rural Unrestricted) 8 50 400 2.15 9.04 0.01 0.37 0.48 1.90 7.9

RT/area hours idle per each RT hours g/hr 

LSDA - (Rural Restricted) 

Dump w/belly dump - IDLE hours2

Diesel 480 0.25 120 0.09 5.87 5.97 2.93 3.37 0.02 1.5

SDNM - (Rural Unrestricted) 

Dump w/belly dump - IDLE hours2

Diesel 99 0.25 25 0.10 5.96 6.06 2.98 3.43 0.01 0.3

Tons LSDA 0.08 0.2

Tons SDNM 0.02 0.0

Tons/all staging 

areas: 

0.10 0.3

1 VMT = vehicles per site *round trip distance over all site prep areas

2 Idle 15 minutes/trip 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Traffic – Exhaust for LSDA Single Track Trails – 5 miles – Commuter Traffic Only

Vehicle Type Type 

Vehicles/site 1

RT 

Distance 

Vehicle Miles 

Traveled (VMT) 

CO 

NO

x

SO

2

VOC 

PM10

CO 

NO

No. of round 

trips (RT) (miles) (VMT /all staging areas) 

g/mile 

LSDA - Restricted 

Commuter Vehicle 

Gas 

Car/Truck 158 50 7920 4.89 0.72 0.006 0.10 0.01 85.24 12.

LSDA - Restricted 

Light Trucks - pick-up/tool Diesel 26 50 1320 1.45 2.53 0.005 0.26 0.16 4.21 7.3

Total Tons for trails 0.0447 0.0

1 Computation for RT for commuter vehicles 

 cars/day 

Feet of trail constructed 

Trail construction rate (hours/foot) 

Shift duration factor (days/hour) 

No. of days required 

Total no. of vehicle round trips required 

Cars 6 26,400 0.01 0.1 26.4 158.4 Light truck w/tools 1 26,401 0.01 0.1 26.401 26.401 Assumes: 6 workers per day; trail construction rate 100 feet/hour; shift duration 10 hours/day; 5280 ft/mi x 5 miles = 

26,400 feet or trail constructed. 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 9. Gravel and Hardening – Sonoran Desert National Monument 

Pad/Road Construction – On-site Emissions – Onsite Heavy Equipment – Dust – Grader O

Area Road Length Road Size Number of Sites Operation fraction for gravel or grading only1 TSP Emissions (Controlled) PM10 Emissions (controlled) 

(miles) (Feet) (acres) (%) T/acre2 T/acre2 

SDNM - staging gravel 1.50 2 100 0.25 0.07 0.02 SDNM - maintenance grading 12 30 43.64 1 100 0.25 0.02 0.01 1 use 1/4 number of days for gravel only 

Onsite Exhaust – Tail Pipe Emissions – Onsite Heavy Equipment – Grader only

Pollutant Emissions (T/hr) 

CO 

NO

x

SO

2

VOC 

PM10

Grader Heavy Equipment Tailpipe Emissions 0.002808 0.002280 0.000002 0.000320 0.000132 

Area Road Length Road Size Number of Sites Operation Hours/acre1 Hours 

CO 

NO

x

(miles) (Feet) (acres) (%) 

SDNM - staging gravel (grader) 1.50 2 100 10 30 0.08 0.068 SDNM - maintenance grading 12 30 43.64 1 100 10 436 1.23 0.995 1 Each Piece of equipment needs 10 hours /acre and there is only one of them 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Traffic – Dust – Vehicle/Travel Emissions Dust (for all site-prep staging areas) – Sonoran Desert Natio

Gravel Only

Vehicle Type Road Type 

Dust Control 

Method 

Vehicle 

Count Vehicles/site RT Distance 

Vehicle Miles 

Traveled (VMT)1

PM10 Emiss

(controlle

Not used (RT/project) (miles) (VMT/projects) (lb/VMT

Commuter Vehicle 

Local Chemical 1 15 4 60 0.19 

Resource Water 1 15 2 30 0.64 

Light Trucks - pick-up/tool 

Local Chemical 1 3 4 12 0.19 

Resource Water 1 3 2 6 0.74 

Shuttle-bus 

Local Chemical 1 3 4 12 0.19 

Resource Water 1 3 2 6 0.87 

Dump w/ bellydump 

Local Chemical 1 40 4 158 0.19 

Resource Water 1 40 2 79 2.09 

5-ton stake bed 

Local Chemical 1 0.5 4 2 0.19 

Resource Water 1 0.5 2 1 0.87 

Water Truck 

Local Chemical 1 3 4 12 0.19 

Resource Water 1 40 2 79 1.53 

Rig Haul Trucks 

Local Chemical 1 4 4 16 0.19 

Resource Water 1 4 2 8 2.22 

Total (ton

1 VMT = vehicles per site *round trip distance over all site prep areas 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Sonoran Desert National Monument – Grading Maintenance Only

Vehicle Type Road Type 

Dust Control 

Method 

Vehicle 

Count Vehicles/site RT Distance1

Vehicle Miles 

Traveled (VMT) 

PM10 Emis

(controll

Not used (RT/project) (miles) (VMT/project) (lb/VMT

Commuter Vehicle 

Local Chemical 1 75 0 0 0.19 

Resource Water 1 75 12 899 0.64 

Light Trucks - pick-up/tool 

Local Chemical 1 15 0 0 0.19 

Resource Water 1 15 12 180 0.74 

Shuttle-bus 

Local Chemical 1 15 0 0 0.19 

Resource Water 1 15 12 180 0.87 

5-ton stake bed 

Local Chemical 1 6.5 0 0 0.19 

Resource Water 1 6.5 12 79 0.87 

Water Truck 

Local Chemical 1 15 0 0 0.19 

Resource Water 1 60 12 719 1.53 

Rig Haul Trucks 

Local Chemical 1 2 0 0 0.19 

Resource Water 1 2 12 24 2.22 

Total (to

1 Travel 1/2 way on 12 mile road and back = 12 miles 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Traffic – Dust – Paved

Vehicle Type 

Vehicle 

Count Vehicles/site 

RT 

Distance 

Vehicle Miles 

Traveled (VMT)1 PM10 Emissions (contr

Not used (RT/project) (miles) (VMT/project) (lb/VMT) 

SDNM Gravel only (area) Commuter Vehicle 1 15 44 660 0.0015 SDNM Grading only (road) 1 75 44 3297 0.0015 SDNM Gravel only (area) Light Trucks - pick-up/tool 1 3 44 132 0.0023 SDNM Grading only (road) 1 15 44 659 0.0023 SDNM Gravel only (area) Shuttle-bus 1 3 44 132 0.0035 SDNM Grading only (road) 1 15 44 659 0.0035 SDNM Gravel only (area) Dump w/ bellydump 1 40 44 1742 0.0362 SDNM Grading only (road) 1 0 44 0 0.0362 SDNM Gravel only (area) 5-ton stake bed 1 0.5 44 20 0.0035 SDNM Grading only (road) 1 6.5 44 288 0.0035 SDNM Gravel only (area) Water Truck 1 3 44 132 0.0158 SDNM Grading only (road) 1 15 44 659 0.0158 SDNM Gravel only (area) Rig Haul Trucks 1 4 44 176 0.0425 SDNM Grading only (road) 1 2 44 88 0.0425 

SDNM Gravel only (area) T

SDNM Grading only (road) T
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Traffic – Exhaust – Tail Pipe Emissions – Transient vehicles

Vehicle Type Type 

Vehicles/site RT Distance 

Vehicle 

Miles 

Traveled 

(VMT)1 CO 

NO

x

SO

2

VOC 

PM10

CO 

NO

x

(RT/project) (miles) (VMT /project) 

g/mile 

SDNM Gravel only (area) Commuter 

Vehicle 

Gas 

Car/Truck 15 50 750 3.20 0.62 0.01 0.10 0.02 5.28 1.03 

SDNM Grading only (road) 75 50 3746 3.20 0.62 0.01 0.10 0.02 26.40 5.15 SDNM Gravel only (area) Light Trucks - 

pick-up/tool 

Diesel 3 50 150 1.93 2.84 0.00 0.37 0.18 0.64 0.94 

SDNM Grading only (road) 15 50 749 1.93 2.84 0.00 0.37 0.18 3.18 4.70 SDNM Gravel only (area) Shuttle-bus Diesel 3 50 150 1.72 5.39 0.01 0.42 0.37 0.57 1.78 SDNM Grading only (road) 15 50 749 1.72 5.39 0.01 0.42 0.37 2.83 8.90 SDNM Gravel only (area) Dump w/ 

bellydump 

Diesel - 

Combo 40 50 1980 2.15 9.04 0.01 0.37 0.48 9.40 39.4

SDNM Grading only (road) 0 0 0 2.15 9.04 0.01 0.37 0.48 0.00 0.00 SDNM Gravel only (area) 5-ton stake 

bed 

Diesel 0.5 50 23 1.72 5.39 0.01 0.42 0.37 0.09 0.27 

SDNM Grading only (road) 6.5 50 327 1.72 5.39 0.01 0.42 0.37 1.24 3.89 SDNM Gravel only (area) Water Truck Diesel 3 50 150 1.72 5.39 0.01 0.42 0.37 0.57 1.78 SDNM Gravel only (area) 40 2 79 1.72 5.39 0.01 0.42 0.37 0.30 0.94 SDNM Grading only (road) Water Truck Diesel 15 50 749 1.72 5.39 0.01 0.42 0.37 2.83 8.90 SDNM Grading only (road) 60 2 120 1.72 5.39 0.01 0.42 0.37 0.45 1.42 SDNM Gravel only (area) Rig Haul 

Trucks 

Diesel - 

Combo 4 50 200 2.15 9.04 0.01 0.37 0.48 0.95 3.98 

SDNM Grading only (road) 2 50 100 2.15 9.04 0.01 0.37 0.48 0.47 1.99 

RT/area hours idle per each RT hours g/hr 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Traffic – Exhaust – Tail Pipe Emissions – Transient vehicles

Vehicle Type Type 

Vehicles/site RT Distance 

Vehicle 

Miles 

Traveled 

(VMT)1 CO 

NO

x

SO

2

VOC 

PM10

CO 

NO

x

(RT/project) (miles) (VMT /project) 

g/mile 

SDNM Gravel only (road) 

Dump w/belly dump - idle hours2

Diesel 40 0.25 10 0.10 5.96 6.06 2.98 3.43 .0021 0.13 

SDNM Gravel only (area) 

Total tons: 0.00889 0.025

SDNM Grading only (road) 

Total tons: 0.01863 0.017

1 VMT = vehicles per site * round trip distance 2 Idle assumed 15 minutes/trip 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 10. Usage – Lower Sonoran Decision Area 

Traffic – Recreational Dust – Lower Sonoran Decision Area – Current 

Season Vehicle Type Road Type Dust Control Method Miles/day No Days Vehicle Miles Traveled (VMT) Factor for winter/Summer (precip) PM10 Emission 

(controlle

(lb/VMT

Summer Primary Unpaved Local Chemical/water 12.0 184 0 0.91 0.66 Winter 108.0 181 0 0.89 0.66 Summer Secondary Unpaved Local none 0.5 184 0 0.91 0.96 Winter 4.9 181 0 0.89 0.96 Summer Jeep Road Local none 2.4 184 446.85714 0.91 0.66 Winter 21.9 181 3956.1429 0.89 0.66 Summer ATV Road Local none 4.0 184 736 0.91 0.62 Winter 36.0 181 6516 0.89 0.62 Summer Motorcycle Trail Local none 3.7 184 683.42857 0.91 0.69 Winter 33 181 6050.5714 0.89 0.69 

Total Unpave

Traffic Emission

Traffic – Dust – Lower Sonoran Decision Area Road (Commuter)

Vehicle Type Road Type Dust Control Method Vehicle Count 

RT 

Distance 

Vehicle Miles 

Traveled (VMT)1 Precip factor 

PM10 Emissio

(controlled) 

(miles) (VMT/LSDA) (lb/VMT) 

Commuter Vehicle 

Local1 Chemical/water 30000 1.82 54600 0.90 0.66 

Resource1 none 30000 0.08 2400 0.90 0.96 

Total tons: 

1 used same split for primary and secondary as above (0.5/12.5)=-.04 0.04*2=0.08 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Usage – Traffic Paved 

Vehicle Type No sites Number Vehicles/year 

RT 

Distance 1

Vehicle Miles 

Traveled (VMT)1

PM10 Emissions

(controlled) 

PM10 

(con

(miles) (VMT/LSDA) (lb/VMT) 

Commuter Vehicle 1 30000 48 1440000 0.002 2,

Total tons: 

1 50-2 miles 

Assume all are average vehicle (2wd, 4wd, even though some may be motorcycles) 

Traffic – Exhaust – Tail Pipe Emissions – Transient vehicles

Type Vehicles/site 

RT 

Distance 

Vehicle Miles 

Traveled 

(VMT) 

CO 

NO

x

SO

2

VOC 

PM10

CO 

NO

x

(miles) (VMT /LSDA) 

Pavement transport g/mile (restricted) car/truck 30000 50 1500000 4.89 0.72 0.01 0.10 0.01 16143.59 2386.14 

total tons exhaust 

onroad: 8.07 1.19 

Use unrestricted here 

Trail Exhaust Primary Unpaved (car) onroad 0 1.98 0.35 0.00 0.05 0.02 0.00 0.00 Secondary Unpaved (truck) onroad 0 4.42 0.90 0.01 0.14 0.02 0.00 0.00 Jeep Road onroad truck 4403 4.42 0.90 0.01 0.14 0.02 42.84 8.75 ATV Road ATV 7252 47.81 0.25 0.03 48.72 1.86 763.71 4.00 Motorcycle Trail ATV 6734 47.81 0.25 0.03 48.72 1.86 709.16 3.71 

total lbs 1515.71 16.46 

Total tons exhaust offroad: 0.76 0.0082 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 11. Usage – Sonoran Desert National Monument 

Estimate of On-road Vehicles and OHVs per Year per Site 

Total On-road Vehicle Usage 

(Existing + Alt. E) 

Usage 

% 

No. of 

Vehicles 

No. of 

Months 

No. of Use 

Days 

Total Vehic

Days 

Every weekend for 6 mo 75% 56.3 6 52.1 2,93Every weekend for 1 mo 100% 75.0 1 8.7 65Weekdays for months above 0% 0.0 7 152.1 Remaining 5 mo 0% 0.0 5 152.1 

Total annual usage 365.0 3,58Avg. veh/day over entire year 

Impact of Alt. E per site as well as current On-road Vehicles 

Total annual usage 1,79Avg. annual veh/day 

OHVs 

Total annual usage 17Avg. annual veh/day 0

Recreational Use Dust 

Vehicle Type Road Type Dust Control Method Miles/day No Days No Vehicles Vehicle Miles Traveled (VMT) Precip Factor for annual PM10 Emissio

Factor (control

(lb/VMT) 

Primary Unpaved Local Chemical/water 2.0 365 0.0 0 0.90 0.66 Secondary Unpaved Resource None 10.0 365 0 0 0.90 0.96 Jeep Road Resource None 10.0 365 0 0 0.90 0.66 ATV Road Resource None 20.0 365 0.49 3584.8214 0.90 0.62 Motorcycle Trail Resource None 20.0 365 0 0 0.90 0.69 

Total Unpaved Road Traffic Emissi
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Sonoran Desert National Monument Road (Commuter)

Vehicle Type Road Type Dust Control Method Vehicle Count RT Distance (miles) 

Vehicle Miles 

Traveled 

(VMT) 

(VMT/SDNM) 

Precip 

Factor for 

annual 

PM10

Emissions

(controlled) 

(lb/VMT) 

Commuter Vehicle 

Local Chemical/Water 1,792.4 2 3585 0.90 0.66 

Resource None 1,792.4 0 0 0.90 0.96 

Tons

Usage – Traffic Paved 

Vehicle Type no sites Number Vehicles/year RT Distance 1 (miles)

Vehicle Miles 

Traveled 

(VMT) 

(VMT/SDNM)

Precip 

factor 

PM10

Emissions

(controlled) 

(lb/VMT)

PM

Emis

(cont

(l

Commuter Vehicle 1 1792 48 86036 0.90 0.0015 13

Tons: 0.07 

Assume all are average vehicle (2wd, 4wd, even though some may be motorcycles) 1 50-2 miles 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Traffic - Exhaust – Tail Pipe Emissions – Transient vehicles

Vehicle 

Type Type Vehicles/ site 

RT 

Distance 

(miles) 

Vehicle Miles 

Traveled 

(VMT) 

(VMT /SDNM) 

CO 

NO

x

SO

2

VOC 

PM10

CO 

NO

x

Pavement transport g/mile (unrestricted) Commuter car/truck 1792 50 89621 3.20 0.62 0.01 0.10 0.02 631.51 123.29 

Total tons onroad: 0.32 0.06 

Use unrestricted below: 

Trail Exhaust Primary Unpaved (car) onroad 0.0 1.98 0.35 0.005 0.05 0.02 0.00 0.0000000 Secondary Unpaved (truck) onroad 0 4.42 0.90 0.006 0.14 0.02 0.00 0.00 Jeep Road onroad truck 0 4.42 0.90 0.006 0.14 0.02 0.00 0.00 ATV Road ATV 0.49 47.81 0.25 0.028 48.72 1.86 0.05 0.0002709 Motorcycle Trail ATV 0 47.81 0.25 0.028 48.72 1.86 0.00 0.00 

Total lbs 0.05 0.0002709 

Total Tons offroad: 0.0000259 0.0000001 

Tons: 0.3157798 0.0616438 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 12. Off-highway Vehicle Races 

OHV Races 

Types Participants No. vehicles Distance per race (mi) Commuter distance (mi) 

Trucks 100 200 -- Motorcycles 100 100 -- Support 100 -- -- Spectators 500 -- -- Total Traffic for Events: 800 50 

Recreational Use Dust + Commuter 

Vehicle Type Road Type 

Dust 

Control 

Method1

Miles/day1 No Vehicles/day 

Vehicle 

Miles 

Traveled 

(VMT) 

Precip 

factor 

PM10 E

Fa

(cont

(lb/V

Commuter Secondary Unpaved Local Water 2.0 800.0 1600 0.90 0Truck racers Jeep Road Resource none 200.0 100 20000 0.90 0Motorcycle racers Motorcycle Trail Resource none 100.0 100 10000 0.90 0

Total Unpaved Road Traffic Emission

1 Assume each vehicle ends up traveling a total of 2 mile on dirt roads, whether in parking areas or on access roads 
Lower Sonoran and Sonoran Desert National Monument 

Resource Management Plan and Environmental Impact Statement April 2012 Air Quality General Conformity Evaluation 

Usage – Traffic Paved 

Vehicle Type No. sites Number Vehicles/year RT Distance (miles)

Vehicle Miles 

Traveled 

(VMT) 

(VMT/SDNM)

Precip 

factor 

PM10

Emissions

(controlled) 

(lb/VMT)

PM10 Em

Commuter Vehicle 1 800 50 40000 0.90 0.002 

Tons: 

Assume all are average vehicle (2wd, 4wd, even though some may be motorcycles) 

Traffic – Exhaust – Tail Pipe Emissions –Transient vehicles

Vehicle 

Type Type Vehicles/site 

RT 

Distance 

(miles) 

Vehicle 

Miles 

Traveled 

(VMT) 

(VMT 

/Event) 

CO 

NO

x

SO

2

VOC 

PM10

CO 

NO

x

g/mile 

LSDA - (restricted) Commuter car/truck 800 50 40000 4.89 0.72 0.01 0.10 0.01 430.50 63.63 

Total tons onroad: 0.22 0.03 

Race Exhaust Use unrestricted below: Truck Onroad truck 100 200 20000 4.42 0.90 0.01 0.14 0.02 194.60 39.74 Motorcycle/ATV ATV 100 100 10000 47.81 0.25 0.03 48.72 1.86 1053.10 5.52 

Total lbs 1247.70 45.25 

Total Tons offroad: 0.62 0.0226 

Tons: 0.84 0.0544