4-127 

Section 92.2.1.4 – Prohibition of Dust Over Property 

Line: 

No OWNER AND/OR OPERATOR of an unpaved 

parking lot shall permit a dust plume from an 

unpaved parking lot to cross a property line, 

provided however, that this requirement shall not 

be applicable where the owner and/or operator 

has applied BEST AVAILABLE CONTROL MEASURES

provided for in this regulation. 

Section 93.2.1.2 New Section: 

New CONSTRUCTION, MODIFICATION, or approvals 

of PAVED roads on which vehicular traffic is equal 

to or greater than 3,000 vehicles per day shall be 

constructed with a PAVED travel section, and 

eight (8) feet of stabilized shoulder adjacent to 

the PAVED travel section where right-of-way is 

available for the stabilized shoulder. Where rightof-way is not available for the full eight (8) feet of 

stabilized shoulder, curbing shall be installed 

adjacent to the shoulder. Stabilized shoulders 

must be maintained in compliance with the 

stabilization standards set forth in Subsection 

93.2.1.7 of this Regulation. 

Section 93.2.2 and Section 93.2.3 New Sections: 

93.2.2 Equipment Prohibition: The use 

of dry rotary brushes and blower 

devices for removal of dirt, rock, or 

other debris from a paved road is 

expressly prohibited, except where 

preceded or accompanied by 

sufficient wetting to limit the visible 

emissions to an opacity of not 

greater that 20% opacity as set 

forth in Subsection 93.5.1.1 

93.2.3 Crack Seal Equipment Requirements: 

After adoption of this Subsection, 
 4-128 

any OWNER AND/OR OPERATOR which utilizes 

crack seal equipment shall acquire or contract to 

acquire only vacuum type crack seal equipment.

Section 94.5.4 New Section: 

No person shall cause or permit the handling, 

transporting, or storage of any material in a 

manner that allows any dust plume to extend 

more than 100 feet, horizontally or vertically, from 

the point of origin or allow any dust plume to 

cross a property line, provided however, that the 

requirements of this Subsection shall not be 

applicable where BEST AVAILABLE CONTROL 

MEASURES required by this Regulation are fully 

implemented. 

Section 94.5.9 New Section: 

Equipment Prohibition: The use of dry rotary 

brushes and blower devices for removal of 

deposited mud/dirt carryout from a paved road is 

expressly prohibited, except where preceded or 

accompanied by sufficient wetting to limit the 

visible emissions to an opacity of not greater than 

20% opacity as set forth in Subsection 94.9.2. 

 

4.8.3 Control Measure Commitments 

4.8.3.1 Commitment to Pave Unpaved Roads

Unpaved roads with identified ADT of 150 or greater will 

be paved by Clark County Public Works, City of North 

Las Vegas Public Works, City of Las Vegas Public 

Works, and City of Henderson Public Works by using 

CMAQ funds by June 1, 2003. The City of Las Vegas 

has made an additional commitment to pave all 

unpaved roads within their jurisdiction by the end of 

2006. An extranet web site tracking the paving of the 

unpaved roads will be established by April 30, 2001 and 

maintained until all unpaved roads with greater than 150 

ADT have been paved. Although this commitment does 

not include unpaved roads less than 150 ADT outside 

the City of Las Vegas, unpaved roads with less than 150 

ADT have and may continue to be paved as part of the 

local ERC program. Annual updates on the progress of 

Commitment To Pave 

Greater than 150 ADT 

Unpaved Roads 
 4-129 

paving all roads will be submitted to Clark County AQD 

and U. S. EPA. 

4.8.3.2 Commitment to Stabilize Shoulders of Paved 

Roads 

Nevada Department of Transportation, Clark County 

Public Works, City of North Las Vegas Public Works, 

City of Las Vegas Public Works, and City of Henderson 

Public Works departments will identify the roadways in 

their respective jurisdictions that have a paved section 

less than 28 feet. For roadways that are not to be 

improved over the next five years, emission estimates 

using a consistent methodology will be calculated by 

each entity in conjunction with CCDCP. The shoulder 

improvements and road paving for unpaved roads with 

less than 150 ADT will be prioritized by each entity for 

their respective jurisdictions based upon emission 

estimates. At a minimum, funds will be obligated to 

improve 33 miles of paved roads with unstabilized 

shoulders to meet Section 93 standards by December 

31, 2003 and all unstabilized shoulders will be improved 

to meet Section standards by December 31, 2006. 

The prioritized list of shoulder improvements to meet 

Section 93 standards and paving of unpaved roads with 

less than 150 ADT, and identified funding sources will 

be incorporated into a plan by each entity for their 

respective jurisdictions. Plans will be completed by 

February 15, 2002. Annual updates on the progress of 

stabilizing shoulders will be submitted to Clark County 

AQD and U. S. EPA. 

The current (fiscal year 2001 through fiscal year 2003) 

Transportation Improvement Program (TIP) commits the 

use of CMAQ funds not to exceed $25 million to meet 

the PM10 SIP commitments. This will result in the 

obligation of these funds to roadway shoulder 

improvements and to the paving of unpaved roads by 

June 30, 2003, in accordance with each entity’s plan. 

The CMAQ funds beyond fiscal year 2003 will be first 

committed to the carbon monoxide transportation 

demand management (TDM) program, and then the 

necessary funds will be committed to complete each 

Commitment To 

Stabilize Shoulders by 

the End of 2006 
 4-130 

entity’s plan for stabilizing shoulders and paving 

unpaved roads by December 31, 2006. 

4.8.4 Commitment to Encourage Adoption of Dust 

Suppressant Product Specifications 

The issue of unintended adverse environmental impacts 

is noted in the discussion of the Section 90 

requirements for disturbed open areas. As noted in the 

analysis, the risks, while thought to be slight, are real. 

The absence of a product standard also prevents 

product applicators, contractors, developers, and public 

agencies from including approved product specifications 

in purchase contracts and bid specifications. Because 

of the scope of this undertaking and the clear 

applicability to areas outside Clark County, the County 

believes that development of the standard and the 

implementation of a limited field testing program needs 

to be done at the state or federal level. As set forth 

under research commitments, Clark County is 

committed to assisting in the funding and coordination of 

research studies that are needed to develop appropriate 

product specifications. Clark County will also work with 

the NDEP and U. S. EPA Region IX to facilitate the 

adoption of dust control product specifications and a 

dust control product field testing program. 

Clark County is an active participant of the dust 

palliatives working group and has helped to sponsor the 

activities of the working group. Clark County will 

continue to support the working group until dust 

palliative standards are adopted at the state or federal 

level. 

4.9 SUMMARY OF CLARK COUNTY CONTROL 

MEASURES AND AIR QUALITY PROGRAMS 

As indicated in the introduction to this chapter, Clark 

County’s PM10 is dominated by geologic materials from 

fugitive dust area sources. Therefore, the focus of this 

SIP is on control of these area dust sources: 

Development of Dust 

Suppressant Product 

Specification a Priority 
 4-131 

disturbed open areas, construction activities, paved 

roads, and unpaved roads. These controls are 

implemented through Sections 90, 91, 92, 93, and 94 of 

the AQD Air Quality Regulations. These regulations are 

very comprehensive and contain a number of innovative 

concepts that Clark County believes will substantially 

reduce emissions from these sources. In particular, 

Clark County believes that the provisions of Section 94 

(Construction Activities) and the companion Section 94 

Handbook will set the standard by which other fugitive 

dust control regulatory programs will be judged in the 

future. 

Some uncertainties in elements of the SIP are noted. 

The emission inventory for unpaved roads is 

acknowledged to have some omissions and the 

inventory for disturbed open areas needs to be updated 

regularly. Certain major sources might have air quality 

impacts on nearby neighborhood areas. Certain 

emission factors for sources that are of critical 

importance in the Las Vegas Valley may require further 

verification. This SIP puts forward a series of ambitious 

research programs to address these uncertainties. 

This SIP demonstrates that all significant sources of 

PM10 in the Las Vegas Valley will have BACM applied at 

the earliest practicable date. These measures also 

meet the U. S. EPA requirements for RACM. 

 4.10 PLAN IMPLEMENTATION 

The State of Nevada program for the control of air 

pollution is established in Chapter 445B of the Nevada 

Revised Statutes (NRS). NRS 445B.100 states that it is 

the public policy of the State of Nevada and the purpose 

of NRS 445B.100 to 445B.640, inclusive, to achieve and 

maintain levels of air quality which will protect human 

health and safety. NRS 445B.500 delegates the 

authority to the District Board of Health of Clark County 

to establish a program for the control of air pollution and 

administer the program within its jurisdiction. The 

District Board of Health of Clark County adopted Air 

Quality Regulation, Section 2 designating the Board of 

Health as the Air Pollution Control Board of Clark 

County and the incorporated cities in Clark County. It 

establishes the Board’s authority to establish such 

Clark County Has the 

Authority to Implement 

the SIP 
 4-132 

emission control requirements as may be necessary to 

prevent, abate, or control air pollution, to establish 

procedures and compliance schedules to enforce those 

regulations, to levy penalties and to seek criminal fines 

against violators. Appendix L provides details on AQD 

dust control enforcement programs. 

The District Board of Health of Clark County ensures 

that the resources needed to implement the air quality 

program are provided. Future year resource 

requirements are projected as follows: 

 FY 2001-2002 $12,133,422 

 FY 2003-2004 $12,573,490 

 FY 2005-2006 $15,079,268 

 

The State of Nevada has the responsibility for ensuring 

the adequate implementation of the Clark County air 

pollution control program. Assurances for this 

requirement are satisfied through NRS 445B.520 which 

allows the State Environmental Commission to 

supersede a County’s program in instances when the 

Commission determines that a local air quality program 

is inadequate. 

 

The State of Nevada 

Has Oversight 
5-1 

CHAPTER 5: DEMONSTRATION OF ATTAINMENT 

OF PM10 NATIONAL AMBIENT AIR QUALITY 

STANDARDS 

5.1 INTRODUCTION 

The purpose of this PM10 State Implementation 

Plan is to assess whether control measures 

adopted since 1998 (Reasonably Achievable 

Control Measures [RACM] and Best Available 

Control Measures [BACM]) reduce PM10 emissions 

sufficiently to demonstrate attainment of the annual 

and 24-hour national ambient air quality standards 

for PM10 no later than December 31, 2001. This 

attainment demonstration, or test, must show that 

the nonattainment region will reach attainment by 

the end of 2001. As demonstrated in this chapter of 

the SIP, the annual standard will be attained in 

2001 but the 24-hour NAAQS cannot be attained 

until 2006. An explanation of why Clark County 

projects attainment of the 24-hour standard in 2006 

instead of the current deadline of 2001 specified by 

the Clean Air Act (Act) is found in Chapter 7. 

The modeling process used to demonstrate 

attainment is described in Appendix K. There are 

several key elements for attainment demonstration, 

including an assessment of future air quality 

conditions, a summary of committed control 

measure impacts, and projected attainment status. 

Future air quality conditions were described in 

Chapter 3. The control measures that have been 

adopted are described in Chapter 4. This chapter 

addresses the impacts of the control measures and 

the projected attainment status. This chapter also 

addresses reasonable further progress and the 

transportation conformity budget. 

5.2 DESIGN VALUE SELECTION 

In accordance with U. S. EPA serious area 

guidance, representative 24-hour and annual 

average PM10 concentrations are needed to 
5-2 

estimate the amount of emission reductions 

required to demonstrate attainment of the 

standards. These high concentrations, referred to 

as design values, are used to determine the type 

and level of controls needed to attain both 

standards. They represent the “starting point” for 

ambient levels of PM10 and determine the quantity 

of reductions necessary to meet the standards. For 

example, if the design value for the annual standard 

is 53 μg/m3, the State Implementation Plan (SIP) 

measures must result in at least a 3 μg/m3

reduction to meet the standard. 

5.2.1 Annual Design Value Concentration 

The base year design value for the Las Vegas 

Valley nonattainment area, determined with 1997, 

1998, and 1999 PM10 monitoring data, is 53 μg/m3

for the annual standard. The development of the 

annual design concentration is relatively 

straightforward. If one or more years of ambient 

PM10 measurements are available for a site, the 

design concentration is the average of the observed 

annual arithmetic means.1 The annual arithmetic 

means were averaged for all monitoring stations 

described in Chapter 2. The only station where the 

average of the means from 1997 through 1999 

exceeded the annual NAAQS was J. D. 

Smith/McDaniel. The McDaniel station was moved 

during the evaluation period due to the loss of the 

lease for the site, and the monitor was located at 

the nearby J. D. Smith Middle School. The site is 

now referred to as the J. D. Smith site. The 

average of the annual arithmetic mean is 53 μg/m3

. 

Therefore, the base year annual design value 

concentration will be 53 μg/m3. 

The base year design value, in conjunction with the 

increase or decrease of emissions from 1998 to 

2001, are then used to project attainment year 

concentrations or design values in 2001. The U. S. 

EPA recommends a combination of receptor and 

 

1 PM10 Guideline Document, United States 

Environmental Protection Agency, Office of Air Quality 

Planning and Standards; Research Triangle Park, North 

Carolina, April 1993. 

Annual Design Value 

is 53 μg/m3
5-3 

dispersion models combined with reliable emission 

projections to model attainment with national 

ambient air quality standards in a future year. 

However, accurately modeling PM10 air quality in a 

future year in accordance with U. S. EPA 

recommendations is a difficult objective. Problem 

areas remain with respect to both emission 

inventories and modeling techniques. There are 

circumstances where receptor models are not 

capable of quantifying absolute PM10 emission 

estimates (such as urban locations where a large 

fraction of particulate emissions are from 

non-traditional sources like construction operations, 

unpaved roads, and wind-blown fugitive dust). 

Dispersion models also have limitations. For 

example, as part of the Las Vegas Valley PM10

Study, the Desert Research Institute attempted to 

model PM10 emissions within a micro-scale area of 

the valley’s nonattainment area utilizing the 

Chemical Mass Balance (CMB) receptor model,2

the Fugitive Dust Model (FDM), and the Industrial 

Source Complex 3 (ISC3) Gaussian 

plume dispersion model.3 The receptor modeling 

results attributed over 80 percent of the ambient 

concentration to fugitive dust sources, but could not 

distinguish between the fugitive dust sources. 

Uncertainties regarding emission rates, in terms of 

timing and location (e.g., construction activities 

versus paved road dust) present problems in 

obtaining valid results from dispersion models. 

These issues are discussed in more detail in 

Appendix K. 

Therefore, the projected annual design value for 

2001 (as an indicator of attainment) will be derived 

by changing the base year design concentration of 

53 μg/m3

 by the same percentage as the change 

between the total amount of PM10 emissions 

emitted throughout the valley between 1998 and 

2001. This application assumes that as valley-wide 

 

2 Fugitive Dust and Other Source Contributions to PM10 in 

Nevada’s Las Vegas Valley. Vol. II, Draft Final Report, Desert 

Research Institute, Reno, Nevada, August 30, 1996. 

3 Fugitive Dust and Other Source Contributions to PM10 in 

Nevada’s Las Vegas Valley. Vol. II, Final Report, Desert 

Research Institute, Reno, Nevada, April 18, 1997.

Accurately Modeling 

PM10 Ambient 

Concentrations for 

Future Years Is 

Problematic
5-4 

PM10 emissions change, then so would design 

concentrations. In other words, there would be a 

proportional relationship between emissions and 

ambient concentration. This methodology is 

commonly known as the proportional rollback 

model. 

Tables 3-3 and 3-8 indicate that emissions 

generated in 2001 would be slightly lower than 

those generated in 1998. The lower emission 

estimates are based on a decrease in vacant land. 

Vacant land acreage is anticipated to decrease as 

development within the BLM disposal area 

continues. Although these numbers are the best 

estimates available, there are no guarantees the 

vacant land will be developed. Due to the 

uncertainty regarding the number of 

acres of vacant land and the corresponding 

emissions from this source, the proportional 

ambient concentration may not be reduced by the 

amount projected by the emissions inventory. 

Therefore, as a conservative, health-protective 

step, the projected annual design value will not be 

lowered but will be set at 53 μg/m3

. 

5.2.2 24-Hour Design Day Concentrations 

The development of the 24-hour design 

concentrations was more complex than the annual 

average. Appendix A details the 24-hour design 

value selection process. The design values exceed 

the 24-hour NAAQS at five monitoring stations in 

Hydrographic Basin 212: Craig Road, East 

Flamingo, Green Valley, J. D. Smith, and Pittman. 

The design value for each site and the date it was 

monitored is presented in Table 3-6. These sites 

are representative of typical conditions and sources 

that lead to high levels of PM10 in the BLM disposal 

area. Other sites within the BLM disposal area with 

similar sources surrounding them may be present 

or develop as growth continues within the 

nonattainment area. In that event, these sites could 

be utilized to represent the sources affecting PM10

levels in these areas and the impact of the 

implementation of the SIP control measures. As 

Although Emissions 

Are Lower in 2001 

Than in 1998, the 

Design Value Is Held 

at 53 μg/m3

Design Values Stay 

the Same for the 

Micro-Scale Sites 
5-5 

these sites are considered representative of 

potential future areas, neither the emissions 

inventories nor the design values were projected for 

2001. Reviewing the meteorological conditions on 

the days these design values were recorded, the 

design values occurred when: 

• hourly average winds exceeded 15 mph; 

• wind speeds exceeded the threshold 

friction velocity for soils within the Las 

Vegas Valley; 

• climatological conditions did not meet the 

Natural Event definition; and 

• PM10 precursors (compounds leading to 

condensable and secondary particulate 

formation) did not play a major role in the 

violations of the NAAQS. 

In addition to the design value for each of the five 

monitoring sites where violations of the NAAQS 

were measured, a valley-wide design value was 

also developed for the purposes of the attainment 

demonstration and the development of a 

transportation conformity budget. Consistent with 

U. S. EPA policy, the 24-hour valley-wide design 

value was chosen on the basis that it was the third 

highest of each of the highest 24-hour 

concentrations measured in a calendar year. It is 

the highest concentration measured in 1998, the 

annual base year; and the day it was measured, 

December 21, 1998, is in roughly the same time 

frame as the other 24-hour design days. The 24-

hour design value for the valley-wide inventory is 

281 μg/m3

. 

As with the annual valley-wide inventory, the total 

emissions for the design day presented in Table 3-5 

are higher than the total 2001 emissions. Again, 

this change is based largely on the acres of vacant 

land that are anticipated being developed between 

1998 and 2001. As previously mentioned, the 

emissions are based upon assumptions that may or 

may not be realized. Therefore, as a conservative, 

health-protective step, the projected valley-wide 24-

hour design value will not be lowered but will be set 

at 281 μg/m3

. This is a conservative approach 

The Valley-Wide 24-

Hour Design Value 

Is 281 μg/m3 
5-6 

because the higher design value will require greater 

controls than a lower design value that would be 

calculated based upon the lower projected 

emissions. 

5.3 RELATING DESIGN VALUES TO EMISSION 

INVENTORIES 

Due to problems with dispersion and receptor 

models described earlier, the proportional rollback 

method was applied to estimate the relationship 

between region-wide PM10 emissions and sampled 

PM10 concentrations. The rollback method 

assumes ambient PM10 concentrations in excess of 

background values are proportional to region-wide 

emissions. As stated previously, the design day 

concentration of 281 μg/m3 is considered 

proportional to the 24-hour valley-wide inventory 

although it was measured at only one site. The 

annual emissions inventory will be reduced by the 

same percentage for each source as the control 

measures will reduce emissions in the J. D. Smith 

micro-inventory area for the sources that appear in 

both inventories. The annual design value of 53 

μg/m3

 will be used for the J. D. Smith annual 

inventory and the valley-wide inventory. 

To ensure the proportional rollback modeling 

results were sound enough to evaluate controls 

needed to attain the NAAQS on a valley-wide basis, 

five additional micro-scale inventories (microinventories) were completed at the five sites where 

design concentrations exceeded the 24-hour 

NAAQS. The 24-hour micro-scale inventories are 

related to the values measured at the respective 

monitoring location and the same rollback method 

will be used to demonstrate attainment. 

Tables 5-1 through 5-8 demonstrate the 

proportional rollback modeling results for the 

attainment year of 2001 using the design values as 

described above. These models present the impact 

on, or contribution to, the design concentrations in 

2001 before any proposed PM10 control reductions 

take place. 

Proportional 

Rollback Modeling 

Will Be Performed 

for Five Micro-Scale 

Sites as Well as 

Valley-Wide 
5-7 

Table 5-1 

2001 Annual BLM Disposal Area Uncontrolled PM10 Emissions, Percent 

Contribution and Concentration 

SOURCES PM10

(tons/year) 

Percent 

Contribution 

Impact on Design 

Concentration (μg/m3

) 

Stationary Point Sources

 Sand & Gravel Operations 627 0.37 0.13 

 Utilities – Natural Gas 199 0.12 0.04 

 Asphalt Concrete Manufacture 171 0.10 0.04 

 Industrial Processes 80 0.05 0.02 

 Other Sources 124 0.07 0.03 

 Total 1,201 0.70 0.26 

Stationary Area Sources

 Small Point Sources 184 0.11 0.04 

 Residential Firewood 89 0.05 0.02 

 Residential Natural Gas 79 0.05 0.02 

 Commercial Natural Gas 33.2 0.02 0.01 

 Industrial Natural Gas 14 0.01 0.00 

 NG – Purchased at the Source – Carried by SWG 210 0.12 0.04 

 Structural / Vehicle Fires / Wild Fires 20 0.01 0.00 

 Charbroiling / Meat Cooking 889 0.52 0.19 

 Disturbed Vacant Lands / Unpaved Parking Lots 33,100 19.40 7.08 

 Native Desert Fugitive Dust 9,520 5.58 2.04 

 Stabilized Vacant Lands Dust 3,640 2.13 0.78 

 Construction Activity Fugitive Dust 23,109 13.54 4.94 

 Windblown Construction Dust 18,381 10.77 3.93 

 Total 89,269 52.32 19.10 

Nonroad Mobile Sources

 Airport Support Equipment 44 0.03 0.01 

 Commercial Equipment 0.3 0.00 0.00 

 Construction & Mining Equipment 428 0.25 0.09 

 Lawn & Garden Equipment 15 0.01 0.00 

 Railroad Equipment 17 0.01 0.00 

 Recreational Equipment 1.0 0.00 0.00 

 McCarran International Airport 297 0.17 0.06 

 Henderson Executive Airport 7 0.00 0.00 

 North Las Vegas Municipal Airport 27 0.02 0.01 

 Nellis Air Force Base 31.9 0.02 0.01 

 Total 867 0.51 0.19 

Onroad Mobile Sources

 Paved Road Dust (Includes Construction Track Out) 55,005 32.24 11.77 

 Unpaved Road Dust 18,932 11.10 4.05 

 Highway Construction Projects Activities 2,782 1.63 0.60 

 Highway Construction Projects – Wind Erosion 1,470 0.86 0.31 

 Vehicular Sulfate PM 489 0.29 0.10 

 Vehicular Tire Wear 100 0.07 0.02 

 Vehicular Brake Wear 163 0.10 0.03 

 Vehicular Exhaust 346 0.20 0.07 

 Total 79,287 46.47 16.96 

Background* 16.5 

Total 170,625 100.00% 53 

*Background includes 13 μg/m3 annual average concentration measured at the Jean monitoring 

station and 3.5 μg/m3 of secondary particulate.
5-8 

Table 5-2 

J. D. Smith 2001 Annual Uncontrolled Emissions Inventory and Design 

Concentration Contributions 

Source Category 

2001 

Emissions 

(tons) 

Percent 

Contribution 

Impact on 

Design 

Concentration 

(μg/m3

) 

Vacant Land 213.4 3.99 1.46 

 Native Desert 2.1 0.04 0.01 

 Unstable 206.0 3.85 1.41 

 Stabilized 5.3 0.10 0.04 

Construction 302.7 5.66 2.06 

 Wind Erosion 109.8 2.05 0.75 

 Construction Activities 186.6 3.49 1.27 

 Track Out 7.9 0.15 0.05 

Unpaved Road Dust 1.8 0.03 0.01 

Paved Road Dust 4,789 89.50 32.67 

Vehicles 

 PM10 35.9 0.67 0.24 

 SOx 51.9 - - 

 NOx 2,262.3 - - 

Stationary Sources 

 PM10 6.3 0.12 0.04 

 SOx 1.6 - - 

 NOx 55.2 - - 

Background* 16.5 

TOTAL 

 PM10 5,350.7 53 

 SOx 53.5 

 NOx 2,317.5 

*Background includes 13 μg/m3 annual average concentration measured at the Jean monitoring 

station and 3.5 μg/m3 of secondary particulate.
5-9 

Table 5-3 

2001 24-Hour BLM Disposal Area Uncontrolled PM10 Emissions, Percent 

Contribution, and Concentration 

SOURCES PM10

(tons/day) 

Percent 

Contribution 

Impact on Design 

Concentration 

(μg/m3

) 

Stationary Point Sources

 Sand & Gravel Operations 1.72 0.24 0.65

 Utilities – Natural Gas 0.55 0.08 0.20

 Asphalt Concrete Manufacture 0.47 0.07 0.18

 Industrial Processes 0.22 0.03 0.08

 Other Sources 0.34 0.05 0.13

 Total 3.29 0.46 1.24

Stationary Area Sources

 Small Point Sources 0.50 0.07 0.19

 Residential Firewood 0.96 0.13 0.36

 Residential Natural Gas 0.22 0.03 0.08

 Commercial Natural Gas 0.09 0.01 0.03

 Industrial Natural Gas 0.04 0.01 0.01

 NG – Purchased at the Source – Carried by SWG 0.58 0.08 0.22 

 Structural / Vehicle Fires / Wild Fires 0.06 0.01 0.02

 Charbroiling / Meat Cooking 2.44 0.34 0.92

 Disturbed Vacant Lands / Unpaved Parking Lots 253 35.15 95.08 

 Native Desert Fugitive Dust 0.00 0.00 0.00

 Stabilized Vacant Lands Dust 28.00 3.89 10.52

 Construction Activity Fugitive Dust 63.31 8.80 23.79

 Windblown Construction Dust 140.53 19.52 52.81

 Total 489.72 68.04 184.04

Nonroad Mobile Sources

 Airport Support Equipment 0.12 0.02 0.05

 Commercial Equipment 0.00 0.00 0.00

 Construction & Mining Equipment 1.17 0.16 0.44

 Lawn & Garden Equipment 0.04 0.01 0.02

 Railroad Equipment 0.05 0.01 0.02

 Recreational Equipment 0.00 0.00 0.00

 McCarran International Airport 0.81 0.11 0.31

 Henderson Executive Airport 0.02 0.00 0.01

 North Las Vegas Municipal Airport 0.07 0.01 0.03

 Nellis Air Force Base 0.09 0.01 0.03

 Total 2.38 0.33 0.89

Onroad Mobile Sources

 Paved Road Dust (Includes Construction Track Out) 150.70 20.94 56.63 

 Unpaved Road Dust 51.87 7.21 19.49

 Highway Construction Projects Activities 7.62 1.06 2.86

 Highway Construction Projects – Wind Erosion 11.20 1.56 4.21 

 Vehicular Sulfate PM 1.34 0.19 0.50

 Vehicular Tire Wear 0.27 0.04 0.10

 Vehicular Brake Wear 0.45 0.06 0.17

 Vehicular Exhaust 0.95 0.13 0.36

 Total 224.40 31.18 84.33

Background* 10.5 

Total 719.78 100.00% 281 

*Background includes 7 μg/m3 24-hour concentration measured at the Boulder City monitoring station on December 21, 

1998, and 3.5 μg/m3 of secondary particulate.
5-10 

Table 5-4 

Craig Road 24-Hour Uncontrolled Emissions Inventory and Design 

Concentration Contributions* 

Source Category Emissions 

(tons) 

Percent 

Contribution 

Impact on Design 

Concentration 

(μg/m3

) 

Vacant Land 4.82 30.79 69.74 

 Native Desert - - - 

 Unstable 4.32 27.60 62.51 

 Stabilized 0.50 3.19 7.23 

Construction 3.43 21.91 49.63 

 Wind Erosion 2.72 17.38 39.36 

 Construction Activities 0.68 4.34 9.84 

 Track Out 0.03 0.19 0.43 

Unpaved Road Dust 0.14 0.89 2.03 

Paved Road Dust 3.98 25.42 57.59 

Unpaved Parking 0.514 3.28 7.44 

 Wind Erosion 0.51 3.26 7.38 

 Vehicles 0.004 0.03 0.06 

Race Tracks 2.43 15.52 35.16 

 Wind Erosion 1.71 10.92 24.74 

 Vehicles 0.72 4.60 10.42 

Vehicles 

 PM10 0.1 0.64 1.45 

 SOx 0.05 - - 

 NOx 2.36 - - 

Stationary Sources 

 PM10 0.24 1.53 3.47 

 SOx 0.0004 - - 

 NOx 0.0583 - - 

Background** 27.5 

TOTAL 

 PM10 15.65 254 

 SOx 0.0504 

 NOx 2.418 

*This inventory was prepared to represent the sources within two kilometers of the Craig Road 

monitoring station on the design day at this site. The relative contribution is based upon the 

design value of 254 μg/m3

. The inventory is considered to be representative of areas with the 

highest recorded PM10 values. 

**Background includes 24 μg/m3 24-hour concentration measured at the Jean monitoring station 

on January 20, 1999, and 3.5 μg/m3 of secondary particulate.
5-11 

Table 5-5 

East Flamingo 24-Hour Uncontrolled Emissions Inventory and Design 

Concentration Contributions*

Source Category Emissions 

(tons) 

Percent 

Contribution 

Impact on Design 

Concentration 

(μg/m3

) 

Vacant Land 2.912 24.38 36.70 

 Native Desert 0.141 1.18 1.78 

 Unstable 2.68 22.44 33.77 

 Stabilized 0.091 0.76 1.15 

Construction 3.92 32.83 49.40 

 Wind Erosion 3.56 29.81 44.87 

 Construction Activities 0.32 2.68 4.03 

 Track Out 0.04 0.33 0.50 

Unpaved Road Dust 0.01 0.08 0.13 

Paved Road Dust 4.96 41.53 62.51 

Vehicles 

 PM10 0.13 1.09 1.64 

 SOx 0.06 - - 

 NOx 3.22 - - 

Stationary Sources 

 PM10 0.01 0.08 0.13 

 SOx 0.001 - - 

 NOx 0.14 - - 

Background** 38.5 

TOTAL 

 PM10 11.942 189 

 SOx 0.061 

 NOx 3.36 

*This inventory was prepared to represent the sources within two kilometers of the East Flamingo 

monitoring station on the design day at this site. The relative contribution is based upon the 

design value of 189 μg/m3

. The inventory is considered to be representative of areas with the 

highest recorded PM10 values. 

**Background includes 35 μg/m3 24-hour concentration measured at the Jean monitoring station 

on March 30, 1999, and 3.5 μg/m3 of secondary particulate.
5-12 

Table 5-6 

Green Valley 24-Hour Uncontrolled Emissions Inventory and Design 

Concentration Contributions*

Source Category Emissions 

 (tons) 

Percent 

Contribution 

Impact on Design 

Concentration 

(μg/m3

) 

Vacant Land 7.33 21.83 57.09 

 Native Desert - - - 

 Unstable 7.29 21.71 56.78 

 Stabilized 0.04 0.12 0.31 

Construction 21.19 63.11 165.03 

 Wind Erosion 18.3 54.50 142.52 

 Construction Activities 2.85 8.49 22.20 

 Track Out 0.04 0.12 0.31 

Unpaved Road Dust 0.017 0.05 0.13 

Paved Road Dust 3.54 10.54 27.57 

Race Tracks 1.26 3.75 9.81 

 Wind Erosion 1.08 3.22 8.41 

 Vehicles 0.18 0.54 1.40 

Vehicles 

 PM10 0.07 0.21 0.55 

 SOx 0.03 - - 

 NOx 1.64 - - 

Stationary Sources 

 PM10 0.17 0.51 1.32 

 SOx 0.19 - - 

 NOx 0.02 - - 

Background** 19.5 

TOTAL 

 PM10 33.577 281 

 Sox 0.22 

 Nox 1.66 

*This inventory was prepared to represent the sources within two kilometers of the Green Valley 

monitoring station on the design day at this site. The relative contribution is based upon the 

design value of 281 μg/m3

. The inventory is considered to be representative of areas with the 

highest recorded PM10 values. 

**Background includes 16 μg/m3 24-hour concentration measured at the Jean monitoring station 

on February 25, 1999, and 3.5 μg/m3 of secondary particulate.
5-13 

Table 5-7 

J. D. Smith 24-Hour Uncontrolled Emissions Inventory and Design 

Concentration Contributions*

Source Category Emissions 

(tons) 

Percent 

Contribution 

Impact on Design 

Concentration 

(μg/m3

) 

Vacant Land 10.08 36.56 63.06 

 Native Desert 0.63 2.28 3.94 

 Unstable 9.4 34.09 58.81 

 Stabilized 0.05 0.18 0.31 

Construction 5.52 20.02 34.53 

 Wind Erosion 5.1 18.50 31.91 

 Construction Activities 0.35 1.27 2.19 

 Track Out 0.07 0.25 0.44 

Unpaved Road Dust 0.004 0.01 0.03 

Paved Road Dust 11.63 42.18 72.76 

Vehicles 

 PM10 0.26 0.94 1.63 

 SOx 0.13 - - 

 NOx 6.6 - - 

Stationary Sources 

 PM10 0.08 0.29 0.50 

 SOx 0.002 - - 

 NOx 0.12 - - 

Background** 45.5 

TOTAL 

 PM10 27.574 218 

 Sox 0.132 

 Nox 6.72 

*This inventory was prepared to represent the sources within two kilometers of the J. D. Smith 

monitoring station on the design day at this site. The relative contribution is based upon the 

design value of 218 μg/m3

. The inventory is considered to be representative of areas with the 

highest recorded PM10 values. 

**Background includes 42 μg/m3 24-hour concentration measured at the Walter Johnson 

monitoring station on March 31, 1999, and 3.5 μg/m3 of secondary particulate.
5-14 

Table 5-8 

Pittman 24-Hour Uncontrolled Emissions Inventory and Design 

Concentration Contributions*

Source Category Emissions 

(tons) 

Percent 

Contribution 

Impact on Design 

Concentration 

(μg/m3

) 

Vacant Land 13.16 67.07 134.48 

 Native Desert - - - 

 Unstable 12.9 65.75 131.83 

 Stabilized 0.26 1.33 2.66 

Construction 1.32 6.73 13.49 

 Wind Erosion 1.12 5.71 11.45 

 Construction Activities 0.19 0.97 1.94 

 Track Out 0.01 0.05 0.10 

Unpaved Road Dust 0.66 3.36 6.74 

Paved Road Dust 2.92 14.88 29.84 

Unpaved Parking 1.14 5.81 11.65 

 Wind Erosion 1.11 5.66 11.34 

 Vehicles 0.03 0.15 0.31 

Vehicles 

 PM10 0.06 0.31 0.61 

 SOx 0.03 - - 

 NOx 1.51 - - 

Stationary Sources 

 PM10 0.36 1.83 3.68 

 SOx 0.02 - - 

 NOx 0.19 - - 

Background** 38.5 

TOTAL 

 PM10 19.62 239 

 Sox 0.05 

 Nox 1.7 

*This inventory was prepared to represent the sources within two kilometers of the Pittman 

monitoring station on the design day at this site. The relative contribution is based upon the 

design value of 239 μg/m3

. The inventory is considered to be representative of areas with the 

highest recorded PM10 values. 

**Background includes 35 μg/m3 24-hour concentration measured at the Jean monitoring station 

on March 30, 1999, and 3.5 μg/m3 of secondary particulate.
5-15 

5.4 PM10 EMISSION LEVELS FOR ATTAINMENT 

OF THE NAAQS 

In order to attain the annual standard by December 

31, 2001, the projected annual design value (53 

μg/m3

) depicted in Tables 5-1 and 5-2 would need 

to be reduced by 5.66 percent, for a total reduction 

of 3 μg/m3. Because there are five representative 

sites and a valley-wide emissions inventory, there 

are six 24-hour design values. The relative impact 

from sources differs based upon the individual site 

parameters or valley-wide characteristic. For 

example, paved road dust contributes over 42 

percent of the total emissions for the J. D. Smith 

micro-scale area and only about 11 percent to the 

emissions surrounding the Green Valley monitoring 

station. As shown in Table 5-9, the percent 

reduction to attain the 24-hour NAAQS (150 μg/m3) 

varies among the sites chosen by between 20.6 

and 46.6 percent, for a total reduction of between 

39 and 131 μg/m3. 

The background concentration for the annual 

design year was determined by comparing the 

annual concentrations measured in 1998 at the 16 

monitoring stations within and near the 

nonattainment area (see Figure 2-1). The lowest 

measured annual average concentration was 

considered background. The location of the 

monitoring station with the lowest annual average 

was reviewed to ensure the monitor was located 

generally upwind of the nonattainment area. The 

lowest annual average concentration was 

measured at the Jean site, which is located 

southeast of the nonattainment area. As 

predominant winds are from the southeast (Figures 

2-4 through 2-6), the annual average concentration 

of 13 μg/m3

 was used for the ambient background 

for the annual inventories. 

A similar process was used to determine the 

ambient background concentration for the 24-hour 

design days. The PM10 concentration measured at 

each of the Clark County Air Quality Division (AQD) 

monitoring stations for each of the design days was 

reviewed to determine the lowest measured 

Annual Emissions 

Levels Determined 

by Percent 

Reduction Required 

at J. D. Smith Site 
5-16 

concentration in the area. When the lowest 

concentration had been determined, the wind roses 

for the design day (Appendix D) were reviewed to 

ensure the minimum measurement had occurred at 

a station upwind of each of the representative 

stations. The ambient background concentrations 

are listed for each 24-hour inventory in Tables 5-3 

through 5-8. 

Background concentrations are assumed to be 

consistent or unchanging from year to year and are 

not subject or amenable to control strategies. This 

is due to the fact that background sources are 

mostly natural PM10 sources that are not within the 

ability of the SIP to control. An example would be 

wind-blown dust from parcels of native desert not 

within the BLM disposal area. Consequently, 

control measures and/or reductions are limited to 

man-made PM10 emission sources. Fortunately, 

reduction in man-made sources of PM10 will allow 

the area to attain the standards. Accordingly, manmade influences on the annual design 

concentrations must be reduced 8.2 percent. The 

reduction from man-made sources for the 

attainment of the 24-hour standard varies between 

25.9 and 48.4 percent, as shown in Table 5-9. The 

higher reductions from man-made sources are 

necessary since almost 25 percent of the annual 

emissions and up to 19.2 percent of the daily 

emissions in 2001 are uncontrollable (natural). The 

proportional rollback method allows the 

establishment of emission levels to demonstrate 

attainment for all design values: annual, 24-hour 

micro-scale, and 24-hour valley-wide.

 

Regional 

Background 

Concentrations 

Assumed to be 

Constant
5-17 

Table 5-9 

24-Hour Attainment Percent and Concentration Reductions 

Location 

Design 

Value 

(μg/m3

) 

Percent 

Reduction for 

Attainment 

Concentration 

Reduction for 

Attainment (μg/m3

) 

Percent Reduction 

From Man-made 

Sources 

Valley-wide 281 46.6 131 48.4 

Craig Road 254 40.9 104 45.9 

East 

Flamingo 

189 20.6 39 25.9 

Green Valley 281 46.6 131 50.1 

J. D. Smith 218 31.2 68 39.4 

Pittman 239 37.2 89 44.4 

5.4.1 Annual Attainment Levels 

Table 5-1 depicts a projected 2001 valley-wide 

emission inventory of 170,625 tons of PM10. A 

reduction of 5.66 percent, or 9,657 tons, is needed 

to attain the annual standard of 50 μg/m3. The 

PM10 emissions allowed during calendar year 2001 

on a valley-wide basis without exceeding the 

annual standard would be 160,968 tons for all 

sources including background conditions, or 

156,634 tons for man-made sources applying the 

proportional relationship between valley-wide 

emissions and the projected design concentration 

as previously described. 

The annual emission inventory for 2001 for the J. D. 

Smith micro-inventory area depicted in Table 5-2 is 

5,351 tons of PM10. A reduction of 5.66 percent, or 

303 tons, is needed to attain the annual standard of 

50 μg/m3

. The estimated amount of PM10 that can 

be emitted during calendar year 2001 within the 

micro-inventory area without an exceedance of the 

24-hour NAAQS would be 5,048 tons for all sources 

including background conditions, or 4,912 tons for 

man-made sources. 

 
5-18 

5.4.2 24-Hour Attainment Levels 

Table 5-10 depicts the projected 24-hour attainment 

levels for the valley and the five micro-scale sites in 

2001. The reduction percentages presented in 

Table 5-9 are applied to the appropriate source 

categories, and the reduction of tons of PM10

emitted for each location are also presented. Table 

5-10 expresses the same information as Table 5-9 

in terms of tons/day rather than percentages. The 

estimated number of tons emitted on the design 

day is summarized in the second column of the 

table. The reduction in emissions required to 

demonstrate attainment from all sources is 

summarized in the third column. The fourth column 

presents the reduction from man-made sources to 

reach attainment, and the last column presents the 

tons/day that may be emitted and attainment of the 

24-hour NAAQS established. The estimated 

emissions after implementation of the control 

measures cannot exceed the values in the last 

column at each location for a successful attainment 

demonstration. 

24-Hour Attainment 

Levels Vary by Site 

Table 5-10 

24-Hour PM10 Attainment Levels by Location 

Location 

Design Day 

Emission 

Inventory 

(tons) 

Reduction to 

Meet 24-Hour 

NAAQS 

(tons) 

Reduction 

from Manmade Sources 

to Meet 24-

Hour NAAQS 

(tons) 

24-Hour 

Attainment 

Levels to Meet 

NAAQS 

(tons) 

Valley-wide 719.78 335.42 348.37 371.41 

Craig Road 15.65 6.40 7.18 8.47 

East Flamingo 11.94 2.46 3.09 8.85 

Green Valley 33.58 15.65 16.82 16.76 

J. D. Smith 27.57 8.60 10.86 16.71 

Pittman 19.62 7.30 8.71 10.91 
5-19 

5.5 ATTAINMENT DEMONSTRATIONS 

Chapter 4 noted the control initiatives implemented 

since the 1998 base year. These initiatives are 

projected to reduce PM10 emissions from disturbed 

vacant land, construction, paved roads, unpaved 

roads, unpaved parking lots, and race tracks. The 

predicted emissions with the proposed control 

initiatives are the basis for the attainment 

demonstrations. Calculations for controlled 

inventories are presented in Appendix L. 

5.5.1 Annual Attainment Demonstration in 2001 

The valley-wide annual emissions inventory with 

control measure reductions as applied to the J. D. 

Smith micro-scale inventory and corresponding 

PM10 concentration is depicted in Table 5-11. The 

reductions correspond to an overall decrease of 

31,942 tons, enough to demonstrate attainment by 

a wide margin. Since there is a proportional 

relationship between emissions and concentrations, 

these valley-wide emission reductions are also 

expected to reduce the annual concentration by 

7 μg/m3 to 46 μg/m3, depending on the location. 

As shown in Table 5-11, these reductions are 

adequate to reach attainment of the annual 

standard of 50 μg/m3

. The anticipated ambient 

concentration of 46 μg/m3 is below the ambient 

standard and even with a small degree of 

uncertainty regarding the inventory, the attainment 

demonstration is sound. The attainment levels in 

Table 5-11 are not intended to be source specific. 

Specifically, the individual stationary sources may 

vary over time, or the exact number of acres that 

are vacant or under construction may vary. Despite 

small variations in individual sources, the total 

valley-wide emissions are anticipated to remain at 

or below the projections shown in Table 5-11. 

With SIP Adopted 

Controls, the Annual 

Concentration Will 

Be Reduced to 46.1 

μg/m3
5-20 

Table 5-11 

2001 Annual BLM Disposal Area Controlled PM10 Emissions and Attainment 

Concentration Contributions 

SOURCES PM10

(TPY) 

Controlled 

PM10 (TPY) 

Percent 

Reduction 

Impact on 

Attainment 

Concentration 

(μg/m3

) 

Stationary Point Sources

 Sand & Gravel Operations 627 627 0.00 0.13

 Utilities – Natural Gas 199 199 0.00 0.04

 Asphalt Concrete Manufacture 171 171 0.00 0.04

 Industrial Processes 80 80 0.00 0.02

 Other Sources 124 124 0.00 0.03

 Total 1,201 1,201 0.00 0.26

Stationary Area Sources

 Small Point Sources 184 184 0.00 0.04

 Residential Firewood 89 89 0.00 0.02

 Residential Natural Gas 79 79 0.00 0.02

 Commercial Natural Gas 33.2 33.2 0.00 0.01

 Industrial Natural Gas 14 14 0.00 0.00

 NG – Purchased at the Source – Carried by SWG 210 210 0.00 0.04 

 Structural / Vehicle Fires / Wild Fires 20 20 0.00 0.00

 Charbroiling / Meat Cooking 889 889 0.00 0.19

 Disturbed Vacant Lands / Unpaved Parking Lots 33,100 21,184 -36.00 4.53 

 Native Desert Fugitive Dust 9,520 9,520 0.00 2.04

 Stabilized Vacant Lands Dust 3,640 3,640 0.00 0.78

 Construction Activity Fugitive Dust 23,109 15,252 -34.00 3.26

 Windblown Construction Dust 18,381 11,861 -35.47 2.54

 Total 89,269 62,976 -30.23 13.47

Nonroad Mobile Sources

 Airport Support Equipment 44 44 0.00 0.01

 Commercial Equipment 0.3 0.3 0.00 0.00

 Construction & Mining Equipment 428 428 0.00 0.09

 Lawn & Garden Equipment 15 15 0.00 0.00

 Railroad Equipment 17 17 0.00 0.00

 Recreational Equipment 1.0 1.0 0.00 0.00

 McCarran International Airport 297 297 0.00 0.06

 Henderson Executive Airport 7 7 0.00 0.00

 North Las Vegas Municipal Airport 27 27 0.00 0.01

 Nellis Air Force Base 31.9 31.9 0.00 0.01

 Total 867 867 0.00 0.19

Onroad Mobile Sources

 Paved Road Dust (Includes Construction Track Out) 55,005 50,822 -7.61 10.87 

 Unpaved Road Dust 18,932 18,932 0.00 4.05

 Highway Construction Projects Activities 2,782 1,836 -34.00 0.39

 Highway Construction Projects – Wind Erosion 1,470 951 -35.29 0.20 

 Vehicular Sulfate PM 489 489 0.00 0.10

 Vehicular Tire Wear 100 100 0.00 0.02

 Vehicular Brake Wear 163 163 0.00 0.03

 Vehicular Exhaust 346 346 0.00 0.07

 Total 79,287 73,638 -7.12 15.75

Background 16.5 

Total 170,625 138,683 -18.95 46.20 
5-21 

As the only monitoring station where violations of 

the annual NAAQS have occurred, an attainment 

demonstration was conducted using the J. D. Smith 

micro-scale inventory. As depicted in Table 5-12, 

the micro-scale emissions are reduced by over 

12 percent. Since there is a proportional 

relationship between emissions and concentrations, 

these emission reductions are also expected to 

reduce the annual concentration by almost 5 μg/m3

, 

with a projected 2001 ambient concentration of 

48.5 μg/m3. The projected value, with SIP PM10

controls implemented, is below the national annual 

standard. Even with some uncertainty regarding 

the emissions inventory, the attainment 

demonstration is conservative in that there is a 

margin between the NAAQS and the projected 

attainment year concentration. 

5.5.2 24-Hour Attainment Demonstration in 2006 

Chapter 4 noted that control measures recently 

adopted as part of this SIP are projected to reduce 

PM10 from vacant land, construction sites, unpaved 

parking, race tracks, and paved road dust. Most of 

the control measures will be fully implemented by 

the end of 2003. These controls were applied to 

the 2001 projected 24-hour emission inventory for 

the BLM disposal area. As presented in Table 

5-13, the controls as partially implemented in 2001 

will not reduce emissions to a level below the 

24-hour NAAQS. Therefore, an extension of the 

attainment date for the 24-hour NAAQS is being 

requested. This request is presented in Chapter 7 

of the SIP. The extension is being requested to 

2006. Most of the controls will be in place by the 

end of 2003, reducing emissions below the 24-hour 

NAAQS for three years ending in 2006. The 2006 

24-hour BLM disposal area inventory with SIPadopted controls fully implemented is presented in 

Table 5-14. The controls were also applied to all 

five of the micro-scale inventories for the areas 

surrounding the five monitoring stations where 

exceedances of the national 24-hour standard were 

recorded. 

With Fully Adopted 

Controls 24-Hour 

Attainment Can Be 

Reached at All 

Micro-Scale Sites 

and Valley-Wide
5-22 

Table 5-12 

J. D. Smith 2006 Annual Controlled Emissions Inventory and Attainment 

Concentration Contributions 

Source Category 

Uncontrolled 

2006 

Emissions 

 (tons) 

Controlled 

2006 

Emissions 

(tons) 

Percent 

Reduction* 

Impact on 

Attainment 

Concentration 

(μg/m3

) 

Vacant Land 213.4 139.3 -34.7 0.95 

 Native Desert 2.1 2.1 0.00 0.01 

 Unstable 206.0 131.8 -36.00 0.90 

 Stabilized 5.3 5.3 0.00 0.04 

Construction 302.7 201.3 -33.50 1.37 

 Wind Erosion 109.8 71.1 -36.00 0.48 

 Construction 

 Activities 186.6 123.2 -34.00 0.84 

 Track Out 7.9 7.1 -11.00 0.05 

Unpaved Road 

Dust 1.8 1.8 0.00 0.01 

Paved Road Dust 4,789 4,311 -10.00 29.41 

Vehicles 

 PM10 35.9 35.9 0.00 0.24 

 SOx 51.9 51.9 - - 

 NOx 2,262 2,262 - - 

Stationary 

Sources 

 

 PM10 6.3 6.3 0.00 0.04 

 SOx 1.6 1.6 - - 

 NOx 55.2 55.2 - - 

Background 16.5 

TOTAL 

 PM10 5,350.7 4,695.5 -12.25 48.5 

 SOx 53.5 

 NOx 2,317.5 

* Sources with zero percent reduction may in fact have controls in place that are reducing PM10

emissions. The zero percent figure represents the fact that these sources are not being 

controlled further as part of the SIP commitments.
5-23 

Table 5-13 

2001 24-Hour BLM Disposal Area Controlled PM10 Emissions and Ambient 

Concentration Contributions 

SOURCES PM10

(TPD) 

Controlled 

PM10 (TPD)

Percent 

Reduction 

Impact on 

Ambient 

Concentration 

(μg/m3

) 

Stationary Point Sources

 Sand & Gravel Operations 1.72 1.72 0.00 0.65

 Utilities – Natural Gas 0.55 0.55 0.00 0.20

 Asphalt Concrete Manufacture 0.47 0.47 0.00 0.18

 Industrial Processes 0.22 0.22 0.00 0.08

 Other Sources 0.34 0.34 0.00 0.13

 Total 3.29 3.29 0.00 1.24

Stationary Area Sources

 Small Point Sources 0.50 0.50 0.00 0.19 

 Residential Firewood 0.96 0.96 0.00 0.36 

 Residential Natural Gas 0.22 0.22 0.00 0.08 

 Commercial Natural Gas 0.09 0.09 0.00 0.03 

 Industrial Natural Gas 0.04 0.04 0.00 0.01 

 NG – Purchased at the Source – Carried by SWG 0.58 0.58 0.00 0.22 

 Structural / Vehicle Fires / Wild Fires 0.06 0.06 0.00 0.02 

 Charbroiling / Meat Cooking 2.44 2.44 0.00 0.92 

 Disturbed Vacant Lands / Unpaved Parking Lots 253 161.92 -36.00 60.85 

 Native Desert Fugitive Dust 0.00 0.00 0.00 0.00 

 Stabilized Vacant Lands Dust 28.00 28.00 0.00 10.52 

 Construction Activity Fugitive Dust 63.31 41.79 -34.00 15.70 

 Windblown Construction Dust 140.53 90.69 -35.00 34.06 

 Total 489.72 327.27 -33.00 122.99 

Nonroad Mobile Sources

 Airport Support Equipment 0.12 0.12 0.00 0.05

 Commercial Equipment 0.00 0.00 0.00 0.00

 Construction & Mining Equipment 1.17 1.17 0.00 0.44

 Lawn & Garden Equipment 0.04 0.04 0.00 0.02

 Railroad Equipment 0.05 0.05 0.00 0.02

 Recreational Equipment 0.00 0.00 0.00 0.00

 McCarran International Airport 0.81 0.81 0.00 0.31

 Henderson Executive Airport 0.02 0.02 0.00 0.01

 North Las Vegas Municipal Airport 0.07 0.07 0.00 0.03

 Nellis Air Force Base 0.09 0.09 0.00 0.03

 Total 2.38 2.38 0.00 0.89

Onroad Mobile Sources

 Paved Road Dust (Includes Construction Track Out) 150.70 139.35 -7.53 52.37 

 Unpaved Road Dust 51.87 40.69 -21.55 15.29

 Highway Construction Projects Activities 7.62 5.03 -34.00 1.89

 Highway Construction Projects – Wind Erosion 11.20 7.27 -35.09 2.73 

 Vehicular Sulfate PM 1.34 1.34 0.00 0.50

 Vehicular Tire Wear 0.27 0.27 0.00 0.10

 Vehicular Brake Wear 0.45 0.45 0.00 0.17

 Vehicular Exhaust 0.95 0.95 0.00 0.36

 Total 224.40 195.31 -12.91 73.41

Background 10.5 

Total 719.78 528.29 -26.53 209.04 
5-24 

Table 5-14 

2006 24-Hour BLM Disposal Area Controlled PM10 Emissions and 

Attainment Concentration Contributions 

SOURCES PM10

(TPD) 

Controlled 

PM10 (TPD)

Percent 

Reduction 

Impact on 

Attainment 

Concentration 

(μg/m3

) 

Stationary Point Sources

 Sand & Gravel Operations 1.72 1.72 0.00 1.18

 Utilities – Natural Gas 0.55 0.55 0.00 0.37

 Asphalt Concrete Manufacture 0.47 0.47 0.00 0.32

 Industrial Processes 0.22 0.22 0.00 0.15

 Other Sources 0.34 0.34 0.00 0.23

 Total 3.29 3.29 0.00 2.25

Stationary Area Sources

 Small Point Sources 0.50 0.50 0.00 0.35

 Residential Firewood 1.12 1.12 0.00 0.77

 Residential Natural Gas 0.25 0.25 0.00 0.17

 Commercial Natural Gas 0.09 0.09 0.00 0.06

 Industrial Natural Gas 0.04 0.04 0.00 0.03

 NG – Purchased at the Source – Carried by SWG 0.58 0.58 0.00 0.39 

 Structural / Vehicle Fires / Wild Fires 0.07 0.07 0.00 0.04 

 Charbroiling / Meat Cooking 2.84 2.84 0.00 1.94 

 Disturbed Vacant Lands / Unpaved Parking Lots 19.30 5.40 -72.00 3.70 

 Native Desert Fugitive Dust 0.00 0.00 0.00 0.00 

 Stabilized Vacant Lands Dust 1.09 1.09 0.00 0.75 

 Construction Activity Fugitive Dust 40.70 13.02 -68.00 8.93

 Windblown Construction Dust 90.34 27.20 -69.89 18.64

 Total 156.91 52.00 -66.73 35.77

Nonroad Mobile Sources

 Airport Support Equipment 0.14 0.14 0.00 0.10

 Commercial Equipment 0.00 0.00 0.00 0.00

 Construction & Mining Equipment 1.36 1.36 0.00 0.94

 Lawn & Garden Equipment 0.05 0.05 0.00 0.03

 Railroad Equipment 0.05 0.05 0.00 0.04

 Recreational Equipment 0.00 0.00 0.00 0.00

 McCarran International Airport 0.57 0.57 0.00 0.39

 Henderson Executive Airport 0.02 0.02 0.00 0.01

 North Las Vegas Municipal Airport 0.07 0.07 0.00 0.05

 Nellis Air Force Base 0.09 0.09 0.00 0.06

 Total 2.36 2.36 0.00 1.62

Onroad Mobile Sources

 Paved Road Dust (Includes Construction Track Out) 161.70 114.86 -28.97 78.71 

 Unpaved Road Dust 55.11 19.50 -64.61 13.36 

 Highway Construction Projects Activities 4.90 1.57 -68.00 1.07 

 Highway Construction Projects – Wind Erosion 7.20 2.22 -69.17 1.52 

 Vehicular Sulfate PM 1.52 1.52 0.00 1.04 

 Vehicular Tire Wear 0.32 0.32 0.00 0.22 

 Vehicular Brake Wear 0.51 0.51 0.00 0.35 

 Vehicular Exhaust 0.91 0.91 0.00 0.62

 Total 232.16 141.40 -39.09 96.90

Background 10.5 

Total 394.72 199.25 -49.52 147.04 
5-25 

Applying the proportional relationship, the valleywide 24-hour concentration impacts are reduced by 

over 60 percent (67.93 μg/m3) due to construction 

emission reductions and 28.97 percent (32.1 μg/m3

) 

due to paved street network PM10 reductions. In 

addition to the other control measures, these 

reductions equal an overall decrease in the 24-hour 

predicted concentration of 134 μg/m3

 as shown in 

Table 5-14. The overall reduction is almost 50 

percent, and the predicted ambient concentration of 

147.04 μg/m3 is sufficiently below the national 24-

hour standard of 150 μg/m3 to clearly demonstrate 

attainment. Additional reductions in the future are 

anticipated from federal mobile source rulemaking. 

Reductions from federal rules were not factored into 

the SIP. 

The reductions described in Chapter 4 were also 

applied to the five representative micro-scale 

inventories surrounding the five ambient monitoring 

sites where violations of the 24-hour national 

standard were measured. The sources in the 

micro-scale inventories varied as well as their 

relative contributions, due in part to meteorology 

and the amount of construction in the areas. The 

reductions and the predicted impacts are depicted 

for each site in Tables 5-15 through 5-19. 

The overall percent reduction at each of the sites 

ranged from 47.68 to 64.92. The predicted ambient 

impacts after controls were well below the national 

24-hour standard of 150 μg/m3

. The 2006 

controlled concentrations ranged from 111.23 

μg/m3 to 134.03 μg/m3, allowing sufficient margin to 

demonstrate attainment at each site. The 

attainment demonstration at the five representative 

sites shows that as growth continues in the 

nonattainment area, the SIP-adopted control 

measures will reduce PM10 concentrations at other 

sites where PM10 sources are present. 

24-Hour Valley-Wide 

Concentration of 

147.04 μg/m3 in 2006 

Overall Percent 

Reduction for MicroScale Inventories 

Ranged from 

48 to 65 
5-26 

Table 5-15 

Craig Road 24-Hour Emissions Inventory and Attainment Concentration 

Contributions 

Source Category 

Uncontrolled 

Emissions 

(tons) 

Controlled 

Emissions 

(tons) 

Percent 

Reduction* 

Impact on 

Attainment 

Concentration** 

(μg/m3) 

Vacant Land 4.82 1.71 -65.00 24.74 

 Native Desert - - - - 

 Unstable 4.32 1.21 -72.00 17.50 

 Stabilized 0.50 0.50 0.00 7.23 

Construction 3.43 1.03 -70.00 14.90 

 Wind Erosion 2.72 0.79 -71.00 11.41 

 Construction 

 Activities 0.68 0.22 -68.00 3.15 

 Track Out 0.03 0.02 -22.00 0.34 

Unpaved Road Dust 0.14 0.14 0.00 2.03 

Paved Road Dust 3.98 2.71 -32.00 39.21 

Unpaved Parking 0.514 0.14 -72.00 2.10 

 Wind Erosion 0.51 0.14 -72.00 2.07 

 Vehicles 0.004 0.00 -48.00 0.03 

Race Tracks 2.43 0.63 -74.00 9.12 

 Wind Erosion 1.71 0.48 -72.00 6.93 

 Vehicles 0.72 0.15 -79.00 2.19 

Vehicles 

 PM10 0.1 0.10 0.00 1.45 

 SOx 0.05 0.05 - - 

 NOx 2.36 2.36 - - 

Stationary Sources 

 PM10 0.24 0.24 0.00 3.47 

 SOx 0.0004 0.0004 - - 

 NOx 0.0583 0.0583 - - 

Background 27.5 

TOTAL 

 PM10 15.65 6.70 -57.17 124.50 

 SOx 0.0504 0.0504 

 NOx 2.418 2.418 

* Sources with zero percent reduction may in fact have controls in place that are reducing PM10

emissions. The zero percent figure represents the fact that these sources are not being 

controlled further as part of the SIP commitments. 

**After implementation of control measures adopted as part of this SIP.
5-27 

Table 5-16 

East Flamingo 24-Hour Emissions Inventory and Attainment Concentration 

Contributions 

Source Category 

Uncontrolled 

Emissions 

(tons) 

Controlled 

Emissions 

(tons) 

Percent 

Reduction* 

Impact on 

Attainment 

Concentration** 

(μg/m3) 

Vacant Land 2.912 0.98 -66.26 12.38 

 Native Desert 0.141 0.14 0.00 1.78 

 Unstable 2.68 0.75 -72.00 9.46 

 Stabilized 0.091 0.09 0.00 1.15 

Construction 3.92 1.17 -70.26 14.69 

 Wind Erosion 3.56 1.03 -71.00 13.01 

 Construction 

 Activities 

0.32 0.10 -68.00 1.29 

 Track Out 0.04 0.03 -22.00 0.39 

Unpaved Road 

Dust 

0.01 0.01 0.00 0.13 

Paved Road Dust 4.96 3.95 -20.36 49.78 

Vehicles 

 PM10 0.13 0.13 0.00 1.64 

 SOx 0.06 0.06 - - 

 NOx 3.22 3.22 - - 

Stationary 

Sources 

 

 PM10 0.01 0.01 0.00 0.13 

 SOx 0.001 0.001 - - 

 NOx 0.14 0.14 - - 

Background 38.5 

TOTAL 

 PM10 11.942 6.248 -47.68 117.25 

 SOx 0.061 0.061 

 NOx 3.36 3.36 

* Sources with zero percent reduction may in fact have controls in place that are reducing PM10

emissions. The zero percent figure represents the fact that these sources are not being 

controlled further as part of the SIP commitments. 

**After implementation of control measures adopted as part of this SIP. 
5-28 

Table 5-17 

Green Valley 24-Hour Emissions Inventory and Attainment Concentration 

Contributions 

Source Category 

Uncontrolled 

Emissions 

(tons) 

Controlled 

Emissions 

(tons) 

Percent 

Reduction* 

Impact on 

Attainment 

Concentration** 

(μg/m3) 

Vacant Land 7.33 2.08 -71.61 16.21 

 Native Desert - - - - 

 Unstable 7.29 2.04 -72.00 15.90 

 Stabilized 0.04 0.04 0.00 0.31 

Construction 21.19 6.25 -70.50 48.68 

 Wind Erosion 18.3 5.31 -71.00 41.33 

 Construction 

 Activities 

2.85 0.91 -68.00 7.10 

 Track Out 0.04 0.03 -22.00 0.24 

Unpaved Road 

Dust 

0.017 0.02 0.00 0.13 

Paved Road 

Dust 

3.54 2.85 -19.49 22.20 

Race Tracks 1.26 0.34 -73.00 2.65 

 Wind Erosion 1.08 0.30 -72.00 2.36 

 Vehicles 0.18 0.04 -79.00 0.29 

Vehicles 

 PM10 0.07 0.07 0.00 0.55 

 SOx 0.03 0.03 - - 

 NOx 1.64 1.64 - - 

Stationary 

Sources 

 

 PM10 0.17 0.17 0.00 1.32 

 SOx 0.19 0.19 - - 

 NOx 0.02 0.02 - - 

Background 19.5 

TOTAL 

 PM10 33.577 11.779 -64.92 111.23 

 SOx 0.22 0.22 

 NOx 1.66 1.66 

* Sources with zero percent reduction may in fact have controls in place that are reducing PM10

emissions. The zero percent figure represents the fact that these sources are not being 

controlled further as part of the SIP commitments. 

**After implementation of control measures adopted as part of this SIP. 
5-29 

Table 5-18 

J. D. Smith 24-Hour Emissions Inventory and Attainment Concentration 

Contributions 

Source Category 

Uncontrolled 

Emissions 

(tons) 

Controlled 

Emissions 

(tons) 

Percent 

Reduction* 

Impact on 

Attainment 

Concentration** 

(μg/m3) 

Vacant Land 10.08 3.31 -67.14 20.72 

 Native Desert 0.63 0.63 0.00 3.94 

 Unstable 9.4 2.63 -72.00 16.47 

 Stabilized 0.05 0.05 0.00 0.31 

Construction 5.52 1.65 -70.19 10.29 

 Wind Erosion 5.1 1.48 -71.00 9.25 

 Construction 

 Activities 

0.35 0.11 -68.00 0.70 

 Track Out 0.07 0.05 -22.00 0.34 

Unpaved Road Dust 0.004 0.00 0.00 0.03 

Paved Road Dust 11.63 8.85 -23.90 55.36 

Vehicles 

 PM10 0.26 0.26 0.00 1.63 

 SOx 0.13 0.13 - - 

 NOx 6.6 6.6 - - 

Stationary Sources 

 PM10 0.08 0.08 0.00 0.50 

 SOx 0.002 0.002 - - 

 NOx 0.12 0.12 - - 

Background 45.5 

TOTAL 

 PM10 27.574 14.152 -48.68 134.03 

 SOx 0.132 0.132 

 NOx 6.72 6.72 

* Sources with zero percent reduction may in fact have controls in place that are reducing PM10

emissions. The zero percent figure represents the fact that these sources are not being 

controlled further as part of the SIP commitments. 

**After implementation of control measures adopted as part of this SIP.
5-30 

Table 5-19 

Pittman 24-Hour Emissions Inventory and Attainment Concentration 

Contributions 

Source Category 

 Uncontrolled 

Emissions 

(tons) 

Controlled 

Emissions 

(tons) 

Percent 

Reduction* 

Impact on 

Attainment 

Concentration** 

(μg/m3) 

Vacant Land 13.16 3.87 -70.58 39.57 

 Native Desert - - - - 

 Unstable 12.9 3.61 -72.00 36.91 

 Stabilized 0.26 0.26 0.00 2.66 

Construction 1.32 .039 -70.20 4.02 

 Wind Erosion 1.12 0.32 -71.00 3.32 

 Construction 

 Activities 

0.19 0.06 -68.00 0.62 

 Track Out 0.01 0.01 -22.00 0.08 

Unpaved Road 

Dust 

0.66 0.66 0.00 6.74 

Paved Road Dust 2.92 2.23 -23.63 22.79 

Unpaved Parking 1.14 0.33 -71.37 3.34 

 Wind Erosion 1.11 0.31 -72.00 3.18 

 Vehicles 0.03 0.02 -48.00 0.16 

Vehicles 

 PM10 0.06 0.06 0.00 0.61 

 SOx 0.03 0.03 - - 

 NOx 1.51 1.51 - - 

Stationary 

Sources 

 

 PM10 0.36 0.36 0.00 3.68 

 SOx 0.02 0.02 - - 

 NOx 0.19 0.19 - - 

Background 38.5 

TOTAL 

 PM10 19.62 7.9018 -59.73 119.25 

 SOx 0.05 0.05 

 NOx 1.7 1.7 

* Sources with zero percent reduction may in fact have controls in place that are reducing PM10

emissions. The zero percent figure represents the fact that these sources are not being 

controlled further as part of the SIP commitments. 

**After implementation of control measures adopted as part of this SIP. 
5-31 

5.6 REASONABLE FURTHER PROGRESS 

Part D of the Clean Air Act, Section 171, indicates 

that the term “Reasonable Further Progress” means 

“such annual incremental reductions in emissions of 

the relevant air pollutant as are required by this part 

or may be reasonably required by the Administrator 

for the purpose of ensuring attainment of the 

applicable national ambient air quality standard by 

the applicable date.” The modeling results 

presented in this chapter support the conclusion 

that the Clark County Nonattainment Area will meet 

the PM10 24-hour standard by the attainment date 

of December 31, 2006. 

According to the General Preamble, the PM10

nonattainment area SIP must include quantitative 

milestones which are to be achieved every three 

years until the area is redesignated attainment and 

which demonstrate reasonable further progress 

(RFP) toward attainment by the applicable date. 

The quantitative milestones allow progress to be 

quantified or measured. Specifically, states should 

identify and submit quantitative milestones 

providing for the amount of emission reductions 

adequate to achieve the NAAQS by the attainment 

date. Reasonable further progress should be met 

by showing incremental emission reductions 

generally sufficient to maintain linear progress 

towards attainment. The milestone achievement 

dates analyzed in this plan are 2003 and 2006. 

These milestones have been addressed by 

quantifying emission reductions which result from 

the implementation of the committed control 

measures after predicted growth has occurred. 

The emissions in the base case (1998), 2003, and 

2006 controlled emission inventories were used to 

develop the RFP analysis shown in Figure 5-1. 

Detailed calculations are presented in Appendix M. 

The adopted control measures used to calculate 

emission reductions were evaluated on a 

cumulative basis to estimate the total valley-wide 

emissions for 2003 and 2006. In general, full 

implementation of the control measures described 

in Chapter 4 was assumed. This is consistent with 

Reasonable Further 

Progress Report 

Due in 2003
5-32 

Figure 5-1 

Reasonable Further Progress Analysis - 24-Hour NAAQS

931.95

276.48

199.25

0

900800700600500400300200100

1000

1998 Base Case 2003 Committed Measures 2006 Committed Measures

24 - Hour

 (Tons) 10 PM

210.70

24 - Hour Attainment Level
5-33 

the implementation schedules contained in the 

rules and the Clark County Air Quality Division 

(AQD) schedules for increasing rule-related 

activities. See Chapter 4 for a discussion of rule 

implementation and effectiveness, including 

schedules of implementation and estimated cost of 

controls. Details on the emission inventory and 

rollback calculations are presented in Appendices 

B, E, and M. The projected emission reductions 

from the control measures result in daily emissions 

of 276.48 tons and 199.25 tons in 2003 and 2006 

respectively. The 77.23 tons-per-day reduction in 

emissions from 2003 to 2006 satisfies the RFP 

requirement. 

5.7 2006 MOBILE SOURCE EMISSIONS BUDGET 

In accordance with the 1990 Clean Air Act 

Amendments (Amendments), conformity 

requirements are intended to ensure that 

transportation activities do not result in air quality 

degradation. Section 176 of the Amendments 

requires that transportation plans, programs, and 

projects conform to applicable air quality plans 

before the transportation action is approved by a 

Metropolitan Planning Organization (MPO). The 

designated MPO for Clark County is the Regional 

Transportation Commission as designated by the 

agreement among general purposes local 

governments and the Governor of Nevada 

(July 8, 1981). 

Section 176(c) provides the framework for ensuring 

that federal actions conform to air quality plans 

under Section 110. Conformity to an 

implementation plan means that proposed activities 

must not: 

(1) cause or contribute to any new violation 

or any standard in any area; 

(2) increase the frequency or severity of any 

existing violation of any standard in any 

area; or 

(3) delay timely attainment of any standard 

or any required interim emission 

reductions or other milestones in any 

area. 

Emissions 

Reductions Between 

the Base Year (1998) 

and 2006 Are 

Anticipated to Show 

Reasonable Further 

Progress 
5-34 

For nonattainment areas required to demonstrate 

reasonable further progress and attainment, U. S. 

EPA requires that the State Implementation Plan 

(SIP) contain documentation of the motor vehicle 

emissions on which the attainment demonstration is 

based. The amount of mobile source emissions 

utilized in the attainment demonstration becomes 

the “emission budget” for highway and transit 

vehicles. The transportation plans and programs 

produced by the transportation planning process 

are required to result in emissions that are within 

the budget. 

The proportional rollback modeling utilized in this 

SIP demonstrates attainment of the annual NAAQS 

in 2001 and the 24-hour NAAQS in 2006. The 

mobile source emissions budget will be based upon 

the annual standard budget until 2003. A 

reasonable further progress demonstration has 

been completed for 2003. The mobile source 

emissions budget for the annual attainment was 

compared to the reasonable further progress 

budget for the 24-hour standard, and the smaller of 

the two budgets (2003 milestone) will be used for 

transportation conformity purposes beginning in 

2003. The mobile source emissions budget for 

attainment of the 24-hour standard has been 

compared to the mobile source emissions budget 

for annual attainment. The smaller of the two 

budgets will be used for transportation conformity 

purposes to ensure attainment of both standards 

beginning in 2006. The projections in the valleywide modeling attainment demonstration indicate 

that with plan implementation, the total daily PM10

emissions in 2001 for all sources in the BLM 

disposal area would be 528.29 tons per day. 

Details of the 2006 projections are presented in 

Appendix E. For conformity purposes, the motor 

vehicle emissions budget includes: 

• regional re-entrained dust from travel on 

paved roads; 

• vehicular exhaust; 

• vehicular brake wear; 

• vehicular tire wear; 

• travel on unpaved roads; and 

• road construction. 

 

The Valley-Wide 24-

Hour Mobile Source 

Emissions Budget 

Will Vary Depending 

on the Year

 
5-35 

The onroad mobile portion of the budget, which 

includes emissions from paved road dust; vehicle 

exhaust; vehicle brake and tire wear; and travel on 

unpaved roads is 194.11 tons per day. Total 

highway construction emissions in 2001 are 

estimated to be 7.64 tons per day. Together, these 

emissions comprise the motor vehicle emissions 

budget for PM10 of 201.75 tons per day. Since the 

inventory of emissions from stationary sources 

participating in the emission reduction credit (ERC) 

program has not been reduced to account for ERC 

credits, the reduction in emissions from the paving 

of unpaved roads is a true reduction of emissions 

into the airshed. For the analysis year 2003, the 

budget will change to 155.77 tons per day. 

Beginning in analysis year 2006, the mobile source 

emissions budget of 141.41 tons per day will be 

used for transportation conformity purposes. The 

development of the mobile source emissions 

budget is explained in detail in Appendix N. 

This budget will be compared to the 2003 RFP 

budget and the 2006 attainment budget during 

future years and adjusted as necessary to ensure 

attainment of both the annual and 24-hour PM10

NAAQS. The lower budget will be used when the 

annual and 24-hour mobile source emission 

budgets differ. 

It is important to note that no additional conformity 

budgets are established with respect to the microscale or micro-inventory modeling. The microinventory analysis addresses attainment of the 24- 

hour standard at representative monitoring sites 

only. The U. S. EPA transportation conformity 

regulations do not require sub-area budgets to be 

established if the implementation plan estimates 

future emissions by geographic sub-area of the 

nonattainment area. According to federal statute, 

(November 24, 1993, Federal Register, page 

62194), the emissions budget applies as a ceiling 

on emissions in the year for which it is defined, 

and for all subsequent years. The transportation 

conformity budget will remain in place until a 

different budget for another year is defined or until a 

future SIP revision modifies the budget. 

The Initial 

Transportation 

Conformity Budget 

Will Be Set at 201.75 

Tons Per Day 
5-36 

5.8 ATTAINMENT DEMONSTRATION SUMMARY

Man-made source categories that contribute 

significantly to the annual design value of 53 μg/m3

(defined as greater than one μg/m3)

1

 identified in 

Table 5-1 are disturbed vacant land, construction 

activities (including wind erosion), paved road dust, 

and unpaved roads. Similarly, significant manmade sources contributing to the 24-hour design 

day values (defined as sources contributing greater 

than five μg/m3) identified in Tables 5-3 through 5-8 

include these sources and unpaved parking and 

race tracks. 

An attainment demonstration for the annual 

standard (50 μg/m3

) during the calendar year of 

2001 was successful due to the implementation of 

control measures, developed as part of this SIP, to 

control PM10 from construction activities, wind 

erosion from disturbed vacant land, and silt loading 

on paved roads. The 24-hour attainment 

demonstration was similarly successful for high 

wind days by December 31, 2006 because of the 

control measures adopted as part of this SIP for 

PM10. Emissions from significant sources that are 

not affected by high winds were also controlled to 

reduce emissions regardless of wind conditions. 

These controls will reduce emissions from 

construction activities, wind erosion from disturbed 

vacant land, unpaved roads, silt loading on paved 

roads, and unpaved parking. Race tracks 

are controlled using the same measures that 

address disturbed vacant land. Chapter 7 

addresses the request for an extension of the 

24-hour NAAQS attainment date to 2006. 

SIP-Adopted Control 

Measures for 

Significant Sources 

Are Adequate to 

Demonstrate 

Attainment of the 24-

Hour and Annual 

NAAQS for PM10
6-1 

CHAPTER 6: MOST STRINGENT CONTROL 

MEASURE ANALYSIS 

6.1 INTRODUCTION 

The attainment demonstration presented in Chapter 5 

concludes that the Annual National Ambient Air Quality 

Standard (NAAQS) for PM10 will be attained by the 

December 31, 2001 deadline established by the 1990 

Clean Air Act Amendments (CAAA). The 24-Hour 

NAAQS for PM10, however, was found to be not 

achievable until 2006, and it was determined that an 

extension of the deadline would be needed. 

Section 188(e) of the CAAA allows U. S. EPA to extend 

the Serious Area attainment date up to five years upon 

application of the state if certain requirements are 

satisfied. Among these are that the Serious Area plan 

contains the most stringent measures (MSMs) included 

in any state implementation plan, or achieved in practice 

in any state, and that can be feasibly implemented in the 

nonattainment area. The plan must also include a 

demonstration of attainment by the most expeditious 

alternative date practicable but no later than December 

31, 2006. 

The purpose of this chapter is to provide documentation 

that this PM10 State Implementation Plan (SIP) does 

include the Most Stringent Measures (MSMs) that are 

included in the implementation plan of any state, or are 

achieved in practice in any state, and can feasibly be 

implemented in the Las Vegas Valley nonattainment 

area. Chapter 7 addresses the formal request for an 

extension of the attainment date for the 24-hour PM10

NAAQS from December 31, 2001 to December 31, 

2006. 

6.2 THE MOST STRINGENT MEASURE 

REQUIREMENT 

To date, U. S. EPA has not issued any policy or 

regulation interpreting the attainment date extension 

Annual PM10 Standard 

Attained by December 

2001 

Clean Air Act Criteria 

for Extension of 

Attainment Date 

Plan Contains Most 

Stringent Control 

Measures 

Implemented in any 

State 
6-2 

requirement for urban areas such as the Las Vegas 

Valley. It has, however, provided preliminary 

interpretation of the section 188(e) requirements in the 

proposed approval of the Maricopa County, Arizona 

PM10 Serious Area Plan (65 FR 19967-19969, April 13, 

2000). Our approach to satisfying the MSM requirement 

is based on the discussion provided by U. S. EPA in this 

proposed rule and as further described below. 

U. S. EPA states that the requirement for most stringent 

measures is similar to the requirement for the Best 

Available Control Measures (BACM). BACM is defined 

to be, among other things, the maximum degree of 

emission reduction achievable from a source or source 

category which is determined on a case-by-case basis 

considering energy, economic, and environmental 

impacts. A similar definition was proposed for a most 

stringent measure as follows: the maximum degree of 

emission reduction that has been required or achieved 

from a source or source category in other SIPs or in 

practice in other states and can feasibly be implemented 

in the area. 

Given the similarity between the BACM implementation 

and MSM requirements, U. S. EPA noted that the 

process for determining MSM should follow a process 

similar to determining BACM, with the added step of 

comparing the potentially most stringent measure 

against the measures already adopted in the area to 

determine if the existing measures are most stringent. 

The following five steps were thus proposed by U. S. 

EPA for determining MSM: 

1. Develop a detailed emission inventory of PM10

sources and source categories; 

2. Model to evaluate the impact on PM10 concentrations 

over the standards of the various source categories 

to determine which are significant for the purposes of 

adopting MSM; 

3. Identify the potentially most stringent measures in 

other implementation plans or used in practice in 

other states for each significant source category and, 

for each measure, determine their technological and 

economic feasibility for the area; 

 

Most Stringent 

Measures Must 

Achieve the Maximum 

Degree of Emissions 

Reduction that Has 

Been Achieved in 

Other States 

Five Steps Used to 

Determine MSM 
6-3 

4. Compare the potentially most stringent measures for 

each significant source category against the 

measures, if any, already adopted for that source 

category; and 

5. Provide for the adoption and expeditious 

implementation of any MSM that is more stringent 

than existing measures or, in lieu of adoption, 

provide a reasoned justification for rejecting the 

potential MSM. 

Steps one and two are the same steps prescribed for 

the BACM analysis as provided in Chapter 4. The 

emissions inventories and modeling work addressed in 

that chapter were reevaluated and determined to apply 

to the MSM analysis. The significant sources that 

contribute to exceedances of the 24-hour PM10

standard, and are thus significant for the purpose of 

adopting MSM, are the same as for BACM (see 

Table 4-1) and are included in the following five source 

categories: 

• Disturbed vacant lands; 

• Unpaved parking lots; 

• Construction activities; 

• Paved road dust; and 

• Unpaved road dust. 

For each of these significant sources, BACM were 

identified and implemented to ensure expeditious 

attainment of the national PM10 standard. Those 

sources determined to be insignificant were not 

considered further for BACM application. 

Because BACM is defined as the best level of control for 

an area, it is possible that satisfying the MSM 

requirement would result in no more controls and no 

more emissions reductions than result from BACM 

implementation. U. S. EPA interprets the strategy in the 

nonattainment provisions of the Act as requiring the 

application of more stringent control measures where 

feasible to offset longer attainment time frames such as 

Clark County is requesting. Two ways were offered as 

means to identify additional controls that could result in 

Significant Sources 

Are Addressed in 

BACM Analysis 

Two Approaches for 

Considering Additional 

Controls 
6-4 

a reduced time frame needed to achieve attainment. 

One is to reduce the threshold for what is considered a 

de minimis (insignificant) source, and the second is to 

reassess any BACM measures rejected during the 

BACM analysis because they could not be 

implemented by the BACM implementation deadline. 

We evaluated the insignificant source contributions to 

determine if new or additional controls (as noted in 

Chapter 4, some controls are already in effect for 

insignificant sources) could be implemented for the 

insignificant sources that would contribute to expediting 

the attainment date. The Valley-Wide 2001 24-Hour 

Inventory, Table L-21, shows a total mass contribution 

after controls of 209 μg/m3 against the standard of 150 

μg/m3

. The total contribution of all insignificant sources, 

those identified in Table 4-1, is 5.1 μg/m3. Eliminating 

100 percent of the insignificant source contributions 

would have no effect on achieving earlier attainment of 

the 150 μg/m3 standard. The same analysis was made 

for the 2003 inventory (see Chapter 5) which showed 

the total controlled concentration to be 184.2 μg/m3, with 

the insignificant sources contributing 13.1 μg/m3. Again, 

eliminating all insignificant source contributions would 

not help advance the attainment date as the remaining 

concentration would still be 171 μg/m3 against the 150 

μg/m3 standard. Since it is necessary to attain three 

consecutive years of data within the 150 μg/m3 standard 

in order to demonstrate attainment of the national 

standard, the earliest date for attainment would still be 

December 31, 2006, our requested extension date, 

even if all insignificant source emissions were 100 

percent controlled. We therefore conclude that applying 

MSM to the de minimis source categories cannot 

meaningfully expedite attainment, and these sources 

are not further analyzed for MSM. 

The second means listed for identifying possible 

additional controls is also not applicable. The initial date 

for BACM implementation was February 8, 1997, and 

there are no potential BACM control measures to 

reconsider now that were rejected because of the 

BACM implementation deadline. 

The third step in determining MSM involves identifying 

the potentially most stringent measures. The extensive 

Elimination of All 

Insignificant Source 

Contributions Will Not 

Advance Attainment 

Date 

Insignificant Sources 

Were Not Further 

Analyzed for MSM 

No Potential BACM 

Control Measures 

Were Rejected Due to 

the Implementation 

Deadline 
6-5 

research that was done to identify potential BACM to be 

considered for implementation in the Las Vegas Valley 

was also used to identify potential MSM. The research 

effort is described in the Section 4.3, Identification of 

Potential Control Measures. 

Generally, Clark County found the control measures 

implemented by the five PM10 serious nonattainment 

areas are potentially the most stringent measures in use 

for control of the same or similar significant sources 

requiring control in the Las Vegas Valley. Close 

attention was given to the controls implemented by each 

of these areas, with particular attention paid to the 

Maricopa Rules 310 and 310.1, amended February 16, 

2000; the South Coast Rule 403, amended December 

11, 1998; and the BACM/MSM Analysis contained in U. 

S. EPA’s Technical Support Document for the Maricopa 

Serious Area PM10 Plan, dated April 6, 2000. 

The remaining steps in the process for determining 

MSM are addressed in the following analysis. 

6.3 THE MOST STRINGENT MEASURE ANALYSIS 

A most stringent measure analysis was performed for 

each of the five significant source categories (disturbed 

vacant lands, unpaved parking lots, construction 

activities, paved roads, and unpaved roads) similar to 

the BACM analysis in Chapter 4. A summary table is 

presented for each source category listing those 

measures found to be potentially the most stringent 

measures implemented by others. The measures 

implemented by Clark County are listed for comparison. 

A discussion of the comparative analysis of the 

measures accompanies each table. Each analysis 

includes a determination of the relative stringency of the 

measures as they apply to the source category. If 

necessary, additional MSMs are identified for 

implementation, or a reasoned justification for rejecting 

potentially more stringent measures is provided. 

6.3.1 Disturbed Vacant Lands 

For Disturbed Vacant Lands, two categories of control 

measures were found to be potential MSMs. 

Close Attention Was 

Given to Control 

Measures in Other 

PM10 Serious 

Nonattainment Areas 

A Summary Table Is 

Provided for Each 

MSM Analysis 
6-6 

Stabilization measures and weed abatement are 

addressed in the following paragraphs. 

6.3.1.1 Stabilization Requirements for Disturbed 

Vacant Lands

The Maricopa Association of Governments (MAG) 

BACM and MSM analyses that are contained in the 

MAG SIP for PM10 (MAG Plan) cited in this chapter 

noted two regulations that contained this control 

measure. These were the South Coast Air Quality 

Management District (SCAQMD) Rule 403 and Clark 

County Section 41. The U.S. EPA determined that 

Maricopa Rule 310.01 was more stringent than Clark 

County Section 41.1 Following the MAG BACM and 

MSM analysis, SCAQMD has updated Rule 403 and 

Maricopa County has updated Rule 310.01. As a result, 

Clark County compared the requirements for this 

source category that are contained in the Clark County 

Air Quality Regulations (AQR) Section 90 to the 

Maricopa Rule 310.01 and the updated SCAQMD Rule 

403. The requirements are summarized in Table 6-1. 

 

1

 Technical Support Document (Notice of Proposed Rulemaking on 

the MAG Serious Area PM10 SIP for the Maricopa County NonAttainment Area), U.S. EPA-Region IX, April 6, 2000. 

Controls for 

Stabilization and Weed 

Abatement 
6-7 

Table 6-1 

Summary of Stabilization Requirements for 

Disturbed Vacant Lands 

Agency Rule # Requirements 

Clark County, 

Nevada 

AQR § 90.2.2.1(a) 

AQR § 90.2.2.1(b) 

AQR § 90.2.2.1(c) 

AQR § 90.4 

• Disturbed areas Σ 5,000 sq. ft., prevent motor vehicle 

 access and stabilize with water, dust suppressants, or 

 gravel 

• Disturbed areas Σ 5,000 sq. ft., stabilize with water, 

 dust suppressants, or gravel 

• Disturbed areas Σ 5,000 sq. ft., apply and maintain 

 AQD/U. S. EPA approved control measure 

• All stabilization subject to drop ball, TFV,b

 or rock test 

• (Proposed) Dust mitigation plans for property owners 

with 10,000 acres or greater 

Maricopa Co., 

Arizona 

Rule 310.01 

§ 301.1 

§ 302.1 

§ 302.2 

• Disturbed areas impacted by motor vehicles Σ 4,356 

 sq. ft., prevent motor vehicle access; or stabilize with 

 dust suppressants or gravel; or apply and maintain an 

 U. S. EPA approved alternative control measure 

• Disturbed areas not impacted by motor vehicles Σ

 21,780 sq. ft., stabilize dust suppressants or gravel; or 

 apply and maintain an U. S. EPA approved alternative 

 control measure 

• All stabilization subject to drop ball, TFV,b vegetation 

cover, or rock test 

SCAQMD,a

California 

403(d)(1) • Disturbed areas must be controlled to prevent visible 

emissions from crossing the property line during winds 

of Ρ 25 mph a

 South Coast Air Quality Management District (SCAQMD) 

b

 Threshold Friction Velocity test

The requirements of Clark County AQR Section 90 and 

Maricopa Rule 310.01 are very similar. For disturbed 

open areas and vacant lots that have been disturbed by 

vehicular traffic, the threshold for stabilization is 

effectively identical. Maricopa County uses a threshold 

of 4,300 square feet for stabilization, whereas Clark 

County sets the threshold at 5,000 square feet. Clark 

County selected the 5,000 square foot threshold 

because the area dimensions of 50 by 100 can be easily 

estimated by inspectors and property owners in the 

field. The 4,300 square foot area equates to “0.1 acre” 

that is specified in the Maricopa rule. A query of the 

Clark County Assessor’s database, which includes all 

parcels and improvement valuations in Clark County, 

found that the vacant land contained in parcels of less 

than 5,000 square feet made up less than one percent 

Clark County and 

Maricopa County 

Requirements Very 

Similar

 

Less than One Percent 

of Vacant Land in 

Parcels Of 5,000 

Square Feet Or Less
6-8 

of the vacant land contained in the BLM disposal 

boundary. 

Maricopa Rule 310 requires that motor vehicle trespass 

or access be prevented on any lot greater than 0.1 acre 

when over 500 cumulative feet of surface has been 

disturbed. In lieu of preventing trespass in such a 

situation, the owner may apply surface gravel or 

chemical/organic stabilizers to all disturbed areas. If 0.5 

acre or more of disturbed surface area exists, the owner 

must stabilize the disturbed surface area. Water is only 

an option where motor vehicle trespass is prevented by 

barriers. (Where there is no evidence of vehicle 

trespass, such as when a lot has been weed abated, 

preventing trespass is not required and the lot may be 

stabilized by water.) Clark County’s Rule 90 is generally 

equivalent except for vacant land where motor vehicle 

trespass/access is occurring. In this situation, Section 

90 is more stringent because there is no explicit 

exemption for lots greater than 5,000 square feet that 

have less than 500 cumulative feet of disturbed surface. 

For open areas not disturbed by vehicular traffic, Clark 

County retains the 5,000 square foot area threshold for 

stabilization, whereas Maricopa Rule 310.01 sets the 

threshold for stabilization at 21,780 square feet (0.5 

acre). The SCAQMD Rule 403 also uses the 0.5 acre 

threshold for all for disturbed areas zoned for residential 

uses. 

The SCAQMD Rule 403(d)(1) utilizes a performance 

standard of no visible emissions over a property line in 

lieu of specific stabilization standards and test methods 

as set forth in the Clark County and Maricopa rules. 

Clark County believes that the specific stabilization 

standards contained the Clark County/Maricopa rules 

provide significantly greater air quality benefits. 

The Clark County approach allows for proactive, yearround enforcement of the control measure, whereas the 

SCAQMD control measure can only be enforced during 

a wind event. Because of distance to property line 

issues, it might be possible to comply with the SCAQMD 

control measure by only stabilizing the outer perimeter 

area of a large disturbed area in some instances.

 

 

Section 90 Is More 

Stringent than 

Maricopa County Rule 

310 

SCAQMD Uses a 

Property Line Visible 

Emissions Standard 

Clark County Provides 

for Proactive YearRound Enforcement
6-9 

The Clark County control measure requires stabilization 

of disturbed areas subject to the control measure within 

30 days of discovery. The Maricopa control measures

mandate stabilization within 60 days of “initial 

discovery.” The SCAQMD control measure does not 

specifically address this issue as the regulation appears 

to be more geared toward construction activities. 

Test methods for stabilization contained in the Clark 

County and Maricopa regulations are identical except 

that the Clark County regulations do not contain test 

methods for vegetation cover. Vegetation is not allowed 

as a stabilization method, except with U. S. EPA 

approval as an alternative stabilization method. 

Based on the comparison of requirements discussed 

above, Clark County finds that the requirements in 

Section 90 of the AQR for disturbed open areas and 

vacant lands are of equivalent stringency as the 

Maricopa Rule 310.01 for disturbed open areas and 

vacant lots impacted by vehicular traffic, and more 

stringent than the SCAQMD Rule 403. For disturbed 

open areas and vacant lots not impacted by motor 

vehicles, Clark County finds that Section 90 of the AQR 

is more stringent than both Maricopa Rule 310.01 and 

SCAQMD Rule 403. 

6.3.1.2 Dust Control for Weed Abatement by Discing 

or Blading 

The MAG Plan noted one regulation that contained this 

control measure. This was SCAQMD Rule 403. 

Following completion of the MAG Plan, SCAQMD has 

updated Rule 403, but has not changed the 

requirements for weed abatement. Maricopa County 

has adopted Rule 310 with specific provisions for weed 

abatement by discing or blading. Clark County 

compared these Maricopa requirements for weed 

abatement with the requirements contained in the Clark 

County AQR Section 90 and the updated SCAQMD 

Rule 403. A summary of these requirements is shown 

in Table 6-2. 

Stabilization Required 

in 30 Days of 

Discovery 

Test Methods 

Clark County 

Requirements 

Equivalent to Maricopa 

County 

Two Programs 

Evaluated for Weed 

Abatement by Discing 

or Blading
6-10 

Table 6-2 

Summary of Weed Abatement Requirements for 

Open Areas and Vacant Lands 

Agency Rule # Requirements 

Clark County, 

Nevada 

AQR § 90.2.2.1(a), (b) 

AQR § 90.2.2.1(c) 

AQR § 90.4 

• Weed abatement of areas Σ 5,000 sq. ft. by discing or 

blading: apply water prior to and during discing and 

blading 

• After discing or blading occurs, stabilize disturbed 

 surfaces with gravel, water, dust palliatives, or paving 

• All stabilization subject to drop ball, TFV,b

 or rock test 

Maricopa Co., 

Arizona 

Rule 310 

§ 308.8 

§ 308.8 

§ 302.3 

• Weed abatement of areas Σ 4,356 sq. ft. by discing or 

 blading: apply water prior to and during discing and 

 blading 

• After discing or blading occurs, stabilize disturbed 

 surfaces with gravel, water, dust palliatives, or paving 

• All stabilization subject to drop ball, TFV,b

 rock test, or 

vegetative cover test 

SCAQMD, 

California 

Rule 403(d)(1) & 

403(h)(H) 

• Disturbed areas must be controlled to prevent visible 

emissions from crossing the property line during winds 

of Ρ 25 mph 

b Threshold Friction Velocity test

The requirements for weed abatement by discing or 

blading contained in Clark County AQR Section 90 and 

Maricopa Rule 310 are virtually identical in terms of the 

stabilization methods and test methods utilized. The 

Maricopa Rule uses a slightly lower action threshold of 

4,300 square feet for weed abatement, whereas Clark 

County sets the threshold at 5,000 square feet. Clark 

County selected the 5,000 square foot threshold 

because the area dimensions of 50 by 100 feet can be 

easily estimated by inspectors and property owners in 

the field. The 4,300 square foot area equates to “0.1 

acre” that is specified in the Maricopa rule. Clark 

County believes that in terms of air quality benefits, the 

two action thresholds for stabilization are equivalent. A 

query of the Clark County Assessor’s database, which 

includes all parcels and improvement valuations in Clark 

County, found that the vacant land contained in parcels 

of less than 5,000 square feet made up less than one 

percent of the vacant land contained in the BLM 

disposal boundary. 

Test Methods 
6-11 

Maricopa Rule 310 classes weed abatement by discing 

or blading as an “earth moving” operation and requires a 

dust control permit to disc or blade any area of 4,300 

square feet or larger. Strictly speaking, this is an 

enforcement mechanism rather than a control measure. 

Clark County is implementing an aggressive 

enforcement and educational program to ensure 

compliance with Section 90 of the AQR and does not 

believe that any additional air quality benefits could be 

achieved by implementing a permitting program. 

In addition to the stabilization methods permitted in the 

Clark County Regulation, the Maricopa rule also allows 

for the use of vegetative cover as a stabilization method. 

This provision could weaken the Maricopa Rule if proper 

techniques are not utilized because of the difficulties in 

establishing vegetation in a dry desert climate and the 

time needed for vegetative cover to achieve sufficient 

growth to provide protective cover. 

The SCAQMD Rule 403(d)(1) utilizes a performance 

standard of no visible emissions over a property line in 

lieu of specific work practice standards and test 

methods as set forth in the Clark County and Maricopa 

rules. As discussed in the stabilization section, Clark 

County does not believe that the property line 

performance standard will be effective in some 

instances or technologically feasible for dust-producing 

operations that occur next to a property line. The use of 

this performance standard was rejected as 

technologically infeasible by Clark County on this basis. 

The South Coast Rule also contains a number of 

exemptions in Subsection 403(h)(H) that are not 

included in the Maricopa and Clark County control 

measures. 

Based on the comparison of requirements discussed 

above, Clark County finds that the requirements in 

Section 90 of the AQR for weed abatement by discing 

and blading are of equivalent stringency as the 

Maricopa Rule 310 and more stringent than the 

SCAQMD Rule 403. 

6.3.2 Unpaved Parking Lots 

The set of control measures for stabilizing unpaved 

Maricopa County 

Requires a Dust 

Control Plan for 

Discing or Blading

 

 

Use of Vegetative 

Cover

SCAQMD Visible 

Emissions Limit 

Clark County 

Requirements of 

Equivalent Stringency 
6-12 

parking lots identified as potential MSM are shown in 

Table 6-3 along with the control measures adopted by 

Clark County. An MSM analysis discussion follows. 

Table 6-3 

Summary of Stabilization Requirements for 

Unpaved Parking Lots 

Agency Rule # Requirements 

Clark County, 

Nevada 

AQR § 92.2.1 

AQR § 90.2.1.2(a) 

AQR § 90.2.1.2(b) 

AQR § 90.2.1.2(c) 

AQR § 90.2.1 

AQR § 92.4 

Stabilize all unpaved parking lots utilized more than 35 

days per year with one of the following methods: 

• Pave; or 

• Stabilize with dust palliatives; or 

• Stabilize with dust palliatives in travel lanes and 2” of 

 uniformly applied gravel in parking areas. 

For parking lots used intermittently for ≤ 35 days/year, 

stabilize as above during parking use and stabilize 

pursuant to AQR Section 90 during non-parking use 

• All stabilization subject to 20 % opacity test method and

maintenance of silt loading of < 0.33 oz/ft2

 or surface 

silt content of ≤ 8 % 

• (Proposed) Prohibitions on new unpaved parking lots 

• (Proposed) Prohibition on dust crossing over a property 

line 

Maricopa Co., 

Arizona 

Rule 310.01 

§ 301.1 

§ 302.1 

§ 303.2 

Stabilize unpaved parking lots ≥ 5,000 sq. ft. utilized more 

than 35 days per year with one of the following methods: 

• Pave; or 

• Stabilize with dust suppressants; or 

• Uniformly apply and maintain surface gravel. 

For parking lots used intermittently for ≤ 35 days/year, 

stabilize as above during parking use 

• All stabilization subject to 20 % opacity test method and

maintenance of silt loading of < 0.33 oz/ft2

 or surface 

silt content of ≤ 8 % 

SCAQMD, 

California 

403(d)(1) • Disturbed areas must be controlled to prevent visible 

emissions from crossing the property line during winds 

of < 25 mph 

• Apply water 

SJVUAPCD 

California 

Regulation 8070 Stabilize unpaved parking lots ≥ 43,560 sq. ft. when used 

for parking with one of the following methods: 

• Stabilize by applying water at least one time per day; or 

• Stabilize with dust suppressants at the manufacturers 

recommended rate for road applications; or 

• Uniformly apply gravel to completely cover the area 

treated. 
6-13 

6.3.2.1 Stabilization Requirements for Unpaved 

Parking Lots

The MAG Plan did not identify any MSMs for unpaved 

parking lots that are not associated with construction 

sites.2

 Clark County notes that the SCAQMD Rule 403 

is not specific to construction activities and would be 

applicable to unpaved parking lots that are not part of a 

construction activity. In addition, Regulation 8070 

adopted by the San Joaquin Valley Unified Air Pollution 

Control District (SJVUAPCD) addresses unpaved 

parking lots that are not utilized as part of a construction 

activity. In addition, Maricopa County has adopted Rule 

310.01 to address unpaved parking lots. 

The requirements for unpaved parking lots contained in 

Clark County AQR Section 92 and Maricopa Rule 

310.01 are virtually identical in terms of the stabilization 

methods and test methods used. The Clark County Rule 

applies to all unpaved parking lots, whereas the 

Maricopa Rule exempts small unpaved parking lots of 

5,000 square feet or less by definition (see 310.01 § 

215). Both rules use identical performance standards 

for visible emissions and surface silt on unpaved 

parking lots. 

Stabilization methods allowed by the Clark County and 

Maricopa rules vary slightly. The Clark County 

requirements are somewhat more restrictive on the use 

of gravel than Maricopa. Specifically, Clark County 

does not allow use of gravel on travel lanes of unpaved 

parking lots and requires two inches of gravel to be 

uniformly applied on parking areas. Although the 

Maricopa requirements are non-specific on the 

application of gravel for unpaved parking lots, the visible 

emissions and surface silt requirements contained in the 

Maricopa rule will generally ensure that gravel is applied 

effectively. 

As noted at the beginning of this section, the SCAQMD 

Rule 403 is nonspecific for unpaved parking lots. 

However, under Subsection 403(d)(1), operators of 

unpaved parking lots are required to prevent visible 

emissions from crossing a property line when wind 

speeds are 25 miles per hour or less. Clark County has 

 

2

 Ibid. 

Other States’ Control 

Measures 

Parking Lots Covered 

by Requirements 

 

Stabilization Methods 

SCAQMD 

Requirements 
6-14 

proposed a prohibition on dust crossing over a property 

line from unpaved parking lots. 

The SJVUAPCD Rule 8070 uses a loose action 

threshold of one acre (43,560 square feet) for 

stabilization of unpaved parking lots, and stabilization is 

only required on days when the parking lot is actually in 

use. The prescribed stabilization methods do not have 

any type of performance standard and, therefore, are of 

limited effectiveness. Prescribed stabilization methods 

include the application of water at least once per day, 

the application of chemical dust suppressants, and the 

application of gravel. Because Rule 8070 contains no 

performance standard for either visible emissions or 

surface stabilization, regulatory compliance is achieved 

with minimal application of one of the prescribed 

stabilization methods without consideration for its actual 

effectiveness. Clark County believes that this control 

measure provides very limited air quality benefits. 

Based on the comparison of requirements discussed 

above, Clark County believes that the requirements in 

Section 92 of the AQR for unpaved parking lots are 

marginally more stringent than the requirements of 

Maricopa Rule 310 and more stringent than the 

requirements contained in the SCAQMD Rule 403 or 

SJVUAPCD Rule 8070. 

6.3.3 Construction Activities 

Research of the source categories included in 

construction activities produced a comprehensive set of 

potential most stringent measures. For analysis 

purposes, these measures have been grouped into a 

total of 13 different categories. A separate summary 

table of the potential MSMs implemented by other 

jurisdictions and those implemented by Clark County is 

provided for each category, as is an MSM analysis of 

the measures in the group. These analyses begin in 

Section 6.3.3.1. 

The Maricopa Plan identified the following MSMs for 

these source categories: 

SJVUAPCD 

Requirements

 

Clark County 

Requirements 

Marginally More 

Stringent

 

 

 
6-15 

• Dust control plans for construction/land clearing; 

• Dust control measures for material storage piles; 

• Bulk material rapid stabilization; 

• Traffic rerouting or rapid cleanup of dust deposits 

on paved roads; 

• Prohibition of work site unpaved haul 

roads/parking/staging areas; 

• Weed abatement operations 

• Require dust control plans for all grading permit 

 activities; and 

• Implement high-wind condition BACMs. 

Clark County found that prohibiting unpaved haul 

roads, parking areas, and staging areas was 

technologically infeasible. In addition, weed 

abatement is not considered a construction activity 

under the Clark County regulatory program, but 

rather maintenance of disturbed vacant land. The 

Clark County control measure for this activity was 

discussed earlier in this Chapter. Where brush and 

vegetation are cleared for construction purposes, 

this activity is addressed under the terms “land 

clearing” or “grubbing.” 

The potential MSM measures discussed in the 

Maricopa Plan predominately originate from 

SCAQMD Rule 403. Requirements from Imperial 

County Regulation VIII and Mojave Desert Air 

Quality Management District (MDAQMD) Rule 403 

are also noted. In the Technical Support Document 

for the Maricopa Serious Area PM10 Plan (TSD),3 the 

U. S. EPA identified additional potential MSMs from 

permit conditions that are being implemented in 

Clark County under previous AQR Section 17. The 

work practices cited in the TSD have been expanded 

and incorporated into the Section 94 Handbook 

which has been adopted by the Clark County Health 

District Board of Health for compliance with the 

requirements of AQR Section 94. Clark County also 

conducted a survey of construction activity controls 

which have been implemented in the southwestern 

United States.4

 The results of this survey are 

summarized in Table 4-3. 

 

3

 Technical Support Document, supra 

4

 Dames & Moore, et. al., supra 

Potential Most 

Stringent Measures 

for Construction 

Prohibiting Unpaved 

Haul Roads Infeasible 

 

Potential Sources of 

Most Stringent 

Measures 

 
6-16 

6.3.3.1 Soil Specific Requirements for Use of 

Surfactants and Tackifiers

The Clark County Section 94 Handbook of Best 

Management Practices for Dust Control (Section 94 

Handbook) sets forth soil-specific requirements for the 

use of surfactants and tackifiers. These requirements 

are summarized in Table 6-4. 

This Requirement Is 

Unique to Clark 

County

Table 6-4 

Summary of Soil Specific Requirements for 

Use of Surfactants and Tackifiers

Agency Rule # Requirements 

Clark County, 

Nevada 

Section 94 

Handbook, 

Figure 4-1 

Section 10-4 

• Classifies soil as having a low, moderate low, moderate 

high, or high emissions potential based on soil silt 

content and optimum moisture content 

• Specific requirements for use of tackifiers & surfactants 

with moderate high and high soil types 

No other agencies 

are implementing this 

control measure 

 

6.3.3.2 Requirement for Dust Control Monitor 

(Manager) at Large Construction Sites

 Table 6-5 summarizes the Clark County requirement for 

a dedicated person as a designated dust control monitor 

for large construction projects. Construction projects 

with 50 acres or greater of active, disturbed area are 

required to have a dust monitor.

This Requirement Is 

Unique to Clark 

County

Table 6-5 

Summary of Requirements for Dust Control 

Monitor (Manager) at Large Construction Sites 

Agency Rule # Requirements 

Clark County, 

Nevada 

AQR § 94.4.11 • Dust control monitor required for Projects with Σ 50 

acres of actively disturbed area 

• Requirement remains in place until less than 50 acres 

are actively disturbed and previously disturbed areas 

have long-term stabilization in place 

No other 

agencies are 

implementing this 

control measure 

 
6-17 

6.3.3.3 Site Specific Dust Control Plan and Permit 

Requirements

Requirements for site-specific dust control plans and/or 

permitting requirements are summarized in Table 6-6. 

Table 6-6 

Summary of Site-Specific Dust Mitigation 

Plan and Permit Requirements

Agency Rule # Requirements 

Clark County, 

Nevada 

AQR § 94.4.8 

AQR § 94.6.8(a) 

AQR § 94.6.7(d) 

AQR § 94.4.9 

Section 94 Handbook 

AQR § 94.4.9 & 

AQR § 94.6.8(a) 

AQR § 94.6.7(d) 

• Dust Control Permit required with BMP for any soildisturbing activities, based on site-specific project 

conditions where construction site ≥ 10 acres, trenching 

Θ 100 ft., demolition > 100 ft. 

• Failure to implement BMP on permit a violation 

• Conducting a dust-producing activity for which no BMP 

specified in permit 

• Site-specific, soil-specific, and phase-specific dust 

mitigation plan implementing BMP required where 

disturbed area/construction site ≥ 10 acres, trenching >

1 mile, demolition with explosives 

• Failure to comply with approved plan a violation of dust 

control permit 

• Conducting a dust-producing activity for which no BMP 

specified in plan a violation 

Maricopa Co., 

Arizona 

Rule 310, 

§ 303 et. sec. 

§ 304.3 

• Dust control plan required for operations that entail 

earthmoving of more Σ0.1 acre 

• Implement one primary and one contingency control for 

each fugitive dust source from Tables 1& 2 

SCAQMD, 

California 

Rule 403(f)(B) • Dust emissions control plan required for operations that 

entail ≥ 50 acres of disturbed land or ≥ 5,000 cubic 

yards of material. 

• Plan must identify all sources of fugitive dust 

• Plan must implement at least one control measure for 

all sources of fugitive dust 

MDAQMD,a

California 

Rule 403-1(C) 

Rule 403-2(C)(3) 

• Dust control plan for construction/demolition source, 

maintain natural topography to extent possible 

• Dust control plan for construction source disturbing 100 

or more acres 

• Describe applicable dust control measures 

• Provide stabilized access to the site as soon as 

possible (prior to project completion) 

• Maintain natural topography to extent possible 

• Construct parking lots and paved roads first, as feasible 

• Construct upwind portions of project first, where 

feasible a

 Mojave Desert Air Quality Management District (MDAQMD)
6-18 

The Clark County dust control permit process serves a 

function similar to the Maricopa requirement for 

submission of dust control plans. Both processes are 

designed to implement control measures required under 

provisions of the respective rules. Clark County does 

not require submission of site-specific dust mitigation 

plans for projects under ten acres or which meet other 

criteria detailed in Table 6-6 in order to expedite 

processing the permits. A “boilerplate” plan may be 

used instead. The applicant must provide the 

information on all dust-producing activities and 

proposed control measures (BMP) as is required for the 

Maricopa Dust Control Plan. Moreover, as noted in 

Table 6-6, an operator is in violation of Section 94 of the 

AQR if he or she engages in a dust-producing activity 

that is not covered under the approved permit. The 

Maricopa action threshold of 0.1 acre is more stringent 

than the Clark County requirement of 0.25 acre for 

obtaining a dust control permit. However, the Clark 

County control measure contains additional 

requirements that may trigger the permit requirement for 

a smaller site and BACM is still required. 

The Clark County requirement for submission of a dust 

mitigation plan is a matter of detail and degree over and 

above the requirement to obtain a dust control permit. 

The requirement for a dust mitigation plan is intended to 

put additional emphasis on soil specificity and phasing 

for larger projects. Where required, the dust mitigation 

plan is made an integral part of the dust control permit. 

The key element of any dust control permit or dust 

control/mitigation plan is the stringency, 

comprehensiveness, and appropriateness of the control 

program put forward in the permit or plan. Both the 

Clark County dust control permit and dust mitigation 

plan requirements are based on implementation of the 

Section 94 Handbook. Clark County believes that this 

compendium of control measures for all types of 

construction activities exceed any other set of control 

measure requirements in terms of comprehensiveness, 

effectiveness, and stringency. Although elements of the 

Maricopa dust control plan process are more stringent 

than the Clark County dust control permit/dust mitigation 

plan program, the overall stringency and benefits of the 

Clark County program equals the Maricopa program 

 

Clark County and 

Maricopa County 

Require Site-Specific 

Review of Projects 

Clark County Dust 

Mitigation Plan Places 

Additional Emphasis 

on Soil Specificity and 

Phasing 

Clark County 

Surpasses Other 

Programs in Terms of 

Comprehensiveness, 

Effectiveness, and 

Stringency
6-19 

for smaller projects and exceeds the Maricopa program 

for larger projects. 

The SCAQMD emission control plan requirements 

require submission of a emission control plan for 

projects of greater than 50 acres. The plan must 

identify all fugitive dust sources and specify mitigation 

measures. However, the menu of mitigation measures 

provided for in the SCAQMD Rule 403 are less 

comprehensive than those found in the Clark County 

Section 94 Handbook, and Rule 403 also lacks the 

visible emission limits contained in Section 94 of the 

AQR. These factors make the Clark County dust control 

permit/dust mitigation plan program significantly more 

stringent than the SCAQMD emission control plan 

requirements. 

The MDAQMD Rule 403-1 requires a dust control plan 

for any construction/demolition project and includes a 

requirement for maintaining the natural topography to 

the extent possible. The MDAQMD Rule 403-2 requires 

a dust control plan for projects of 100 acres or larger. 

The plan must identify applicable control measures, and 

the plan requirements specify special conditions for 

these large projects. These include providing stabilized 

access to the site as soon as possible (but prior to 

project completion); maintenance of natural topography 

to extent possible; constructing parking lots and paved 

roads first (as feasible); and constructing upwind 

portions of project first where feasible. The Clark County 

BMPs include stabilizing access roads for the duration 

of the project and applying paving as soon as possible 

to all future roadway areas. The air quality benefits and 

technical feasibility of maintaining the natural 

topography to the extent possible is not known for Clark 

County, but is thought to be very small. 

Overall, the Clark County dust control permit/dust 

mitigation plan program provides a significantly more 

stringent program than the combined elements of 

MDAQMD Rule 403-1 and 403-2. 

6.3.3.4 Visible Emission Limits

Requirements for limiting visible emissions 

from construction activities in Clark County 

 

SCAQMD Dust Control 

Plan Requirements 

MDAQMD Dust Control 

Plan Requirements 

 

 
6-20 

and other areas are summarized in Table 6-7. 

Table 6-7 

Summary of Requirements for Limiting Visible Emissions 

Agency Rule # Requirements 

Clark County, 

Nevada 

AQR § 94.5.2 

AQR § 94.6.8(d) 

AQR § 94.6.8(b) 

• Limit visible emissions from all construction activities to 

Ρ 20 % opacity 

• Limit visible dust plume from all construction activities 

to Ρ 100 yards 

• (Proposed) Limit a visible dust plume to less than 100 

feet 

• (Proposed) Prohibit dust from crossing a property line 

Maricopa Co., 

Arizona 

Rule 310, 

§ 301 

• Limit visible emissions from all construction activities to 

Ρ 20 % opacity 

SCAQMD, 

California 

Rule 403(d)(1) & 

Table 2 (1a-1) 

• Prevent visible emissions from all construction activities 

from crossing property line 

• Limit visible dust plume from all earth-moving activities 

to ≤ 100 feet 

SMAQMD,a

California 

Rule 403 • Take every reasonable precaution to prevent visible 

emissions construction activities from crossing property 

line a

 Sacramento Metropolitan Air Quality Management District (SMAQMD) 

 

Section 94 of the Clark County AQR contain two limits 

on visible emissions from construction activities. The 

primary performance standard is the requirement that 

visible emissions not exceed an opacity reading of 20 

percent based on 12 or 24 time-averaged readings 

taken at 15-second intervals. A secondary requirement 

is that visible plumes not extend for more than 100 

yards. Although this standard is considered relatively 

easy to enforce, the relationship between the plume 

length standard and degree of control is less certain 

than that of the opacity standard. Clark County has 

therefore retained the plume length standard as a 

secondary means of establishing that excessive 

emissions are occurring. Clark County has also 

proposed two new requirements where BACM has not 

been fully implemented. The first is to limit a visible dust 

plume to less than then 100 feet. The second is to 

prohibit dust from crossing a property boundary. 

Maricopa County Rule 310 contains a 20 percent 

opacity limitation that is identical to the Clark County 

requirement. The SCAQMD contains a plume length 

Primary Clark County 

Visible Emissions 

Limit 20 Percent 

Opacity

Maricopa County 

Visible Emissions 

Limit 20 Percent 

Opacity
6-21 

limitation of 100 feet as an alternative to conducting 

upwind/downwind monitoring and a requirement that no 

visible emissions be permitted to cross a property line. 

The Sacramento Metropolitan Air Quality Management 

District (SMAQMD) Rule 403 contains a requirement 

that “reasonable precautions” be taken to prevent dust 

from crossing a property line. As previously discussed 

in this chapter, Clark County rejected the prevention of 

dust crossing a property line as technologically 

infeasible. The SCAQMD 100-foot limit on dust plume 

length is clearly more stringent than the 100-yard 

requirement contained in the Clark County control 

measure. However, because of the uncertainties 

related to the level of control achieved by this 

requirement, Clark County believes that the 20 percent 

opacity requirement implemented in AQR Section 94 is 

of equal or greater stringency than the SCAQMD 

requirement and provides better air quality benefits. 

6.3.3.5 BACM Required 24 Hours a Day, Seven Days 

a Week

Requirements for maintaining dust control at 

construction sites 24 hours a day, seven days a week, 

are summarized in Table 6-8. Clark County finds the 

intent and application of these control measures to be 

equally stringent. 

 

SCAQMD Imposes 

100-Foot Plume 

Length Limit 

Clark County’s 

Requirements Are of 

Equal or Greater 

Stringency

Table 6-8 

Summary of Requirements for Applying BACM 

24 Hours a Day, Seven Days a Week 

Agency Rule # Requirements 

Clark County, 

Nevada 

AQR § 94.5.2 • Maintain BACM throughout the site for the duration of 

the project to limit wind erosion and particulate 

emissions 

• BACM required 24 hours a day, seven days a week 

Maricopa Co., 

Arizona 

Rule 310, 

§ 304.3 

• Control measures to be applied to all actual and 

potential fugitive dust sources, before, after, and while 

conducting any dust-generating operation, including 

weekends, after work hours, and on holidays 
6-22 

6.3.3.6 Cessation of Construction Activities During 

High Winds

The Clark County requirements for ceasing construction 

activities that contribute to a violation and related 

requirements from other areas are summarized in 

Table 6-9. 

Clark County and 

Maricopa County 

Requirements Are 

Equally Stringent

Table 6-9 

Summary of Requirements for High Wind Conditions 

Agency Rule # Requirements 

Clark County, 

Nevada 

AQR § 94.5.4 • Requires cessation of all activities that cause fugitive 

dust emissions to exceed 20 % opacity in spite of the 

use of BACM 

• Requires that watering equipment continue to operate 

during high-wind conditions 

Maricopa Co., 

Arizona 

Rule 310, 

§ 300.1 

Table 2 BACM 1A 

• Provides that winds over 25 mph shall be an 

“affirmative defense” where dust emissions exceed 20 

% opacity and all applicable BACM have been 

implemented 

• High wind BACM mandates cessation of dust 

generating activities after 60-minute average of winds 

Θ25 mph 

SCAQMD, 

California 

Rule 410.1(d) • Requires that additional dust mitigation measures be 

implemented for disturbed areas and storage and 

handling of bulk materials, and requires cessation of 

agricultural tilling when winds exceed 25 mph 

Clark County is the only agency that has implemented 

an unconditional requirement to cease dust-generating 

construction activities when high-wind conditions 

overwhelm BACM controls for these activities. The 

Clark County requirement sets the most stringent 

standard possible for high winds because no lower wind 

speed limit is set under which construction activities 

cannot be halted when wind overwhelms the BACM for 

dust-generating activities. In addition, the requirement 

specifically mandates that water trucks and water pulls 

continue to operate after other dust-producing activities 

have been curtailed. 

Maricopa County Rule 310 provides that winds over 

25 mph can be used as an “affirmative defense” in an 

enforcement action where all applicable BACM has 

Clark County 

Requirements 
6-23 

been applied and the 20 percent opacity limit has been 

violated. However, the rule does not mandate cessation 

of dust-producing activities in order to utilize this 

defense. However, BACM No. 1A from the high-wind 

BACM table requires that dust-generating activities 

cease when the average wind speed exceeds 25 miles 

per hour over a 60-minute period. This BACM for high 

wind effectively sets a curtailment requirement for high 

winds. However, this curtailment wind threshold is 

significantly less stringent than the Clark County 

threshold and will also be harder to enforce. In addition, 

the Clark County control measure requires that water 

applications continue after dust-producing activities 

have been halted. The Maricopa County BACM do not 

include this requirement. Clark County finds the 

requirements of AQR Section 94.5.4 to be more 

stringent than Rule 310, Section 301.1 for curtailing 

emissions during high-wind conditions at construction 

sites. 

The SCAQMD Rule 403.1 requires that additional dust 

mitigation measures be employed for disturbed areas 

when wind speeds exceed 25 mph. However, the rule 

does not mandate cessation of construction activities 

during high winds. Therefore, Clark County finds the 

requirements of AQR Section 94.5.4 to be more 

stringent than Rule 403.1 for curtailing emissions during 

high-wind conditions. 

6.3.3.7 Control Measures for Stabilizing Disturbed 

Soil

Requirements for stabilizing disturbed soil are 

summarized in Table 6-10. 

Clark County has implemented an extensive and 

integrated set of control measures for disturbed areas of 

construction sites. These measures are implemented in 

conjunction with Clark County’s dust control permit and 

dust mitigation plan requirements, and the AQR Section 

94 requirement that emissions be controlled 24 hours a 

day, seven days a week. Both short-term and long-term 

stabilization are addressed in the BMP. The two other 

agencies with the most extensive control measure 

requirements for construction site disturbed areas are 

Maricopa County and SCAQMD. Based on a 

comparison of these measures, it appears that Clark 

When High Winds 

Overwhelm BACM 

Controls, Construction 

Activities Must Cease

Maricopa County 

Requirements 

Clark County 

Stabilization Measures 

Are the Most Stringent
6-24 

County requirements are the most stringent for this 

control of disturbed soil. 

Clark County’s 

Requirements Are the 

Most Stringent

Table 6-10 

Summary of Control Measures for 

Stabilizing Disturbed Soil 

Agency Rule # Requirements 

Clark County, 

Nevada 

AQR Section 94.6.8(d) 

AQR Section 94.6.8(b) 

Section 94 Handbook 

CST 10 

CST 10-1 

CST 10-2 

CST 10-3 

CST 10-4 

CST 10-5 

CST 10-6 

CST 10-7 

CST 11 

CST 11-1 

CST 11-2 

CST 11-3 

CST 11-4 

CST 11-5 

CST 11-6 

Visible Emission Limits: 

• Limit visible emissions from all construction activities to 

Ρ 20 % opacity 

• Limit visible dust plume from all construction activities 

from extending more than 100 yards 

• (Proposed) Limit visible emission plumes to less then 

100 feet 

• (Proposed) Prohibit dust from crossing a property line 

Requirements for All Projects: 

• Stabilize disturbed soil throughout construction site 

• Stabilize disturbed soil between structures 

Control Measures for All Soil Types: 

• Apply water to stabilize disturbed soil throughout 

construction site 

• Limit vehicle traffic and disturbance on soils where 

possible 

• If interior block walls are planned, install as early in the 

construction as possible 

• Apply dust palliative based on soil type 

Control Measures For Specific Soil Types: 

• Apply palliative such as gypsum mulch (high soil) 

• Install perimeter wind barrier (high soil) 

• Apply water to stabilize disturbed soils - soils must be 

kept in a damp, crusted, or covered condition (moderate 

high, moderate low and low soils) 

Requirements for Large Tracts: 

• Stabilize soil to comply with drop ball, TFV, or rock test 

• Prevent access to limit soil disturbance 

Control Measures for All Soil Types-Large Tracts: 

• Prevent access by fencing, ditches, vegetation, berms, 

or other suitable barrier or means approved by the 

Control Officer 

• Install perimeter wind barriers three (3) to five (5) feet 

high made of material with a porosity of 50 % or less 

• Plant perimeter vegetation early. Use of native and 

drought-tolerant plants with greater than 50 % silhouette 

area is encouraged 

• Stabilize disturbed soil with dust palliative for long-term 

stabilization 

• Stabilize disturbed soil with vegetation for long-term 

stabilization 
6-25 

Table 6-10 

Summary of Control Measures for Stabilizing Disturbed Soil 

(continued) 

Agency Rule # Requirements 

Maricopa Co., 

Arizona 

Rule 310, Section 301 

Section 302.3 

• Pave or apply surface rock for long-term stabilization 

• Limit visible fugitive dust emissions ≤ 20 % opacity 

• For inactive disturbed areas, stabilize soil to comply 

with drop ball, TFV, vegetative cover, or rock test 

SCAQMD, 

California 

Rule 403(d)(1) 

Rule 403, Table 2 (3a) 

Rule 403, Table 2 (3b) 

Rule 403, Table 2 (3c) 

Rule 403, Table 2 (3d) 

• Prevent visible emissions from disturbed surface area 

from crossing a property line 

• Apply water to at least 80 % of all inactive disturbed 

surface areas on a daily basis when there is evidence 

of wind-driven fugitive dust, excluding any areas which 

are inaccessible to watering vehicles due to excessive 

slope or other safety conditions; or 

• Apply dust suppressants in sufficient quantity and 

frequency to maintain a stabilized surface; or 

• Establish a vegetative ground cover within 21 days 

after active operations have ceased - ground cover 

must be of sufficient density to expose less than 30 % 

of unstabilized ground within 90 days of planting, and at 

all times thereafter; or 

• Utilize any combination of control actions (3a), (3b), 

and (3c) such that, in total, these actions apply to all 

inactive disturbed surface areas 

6.3.3.8 Control Measures for Stabilizing 

Construction Haul Roads and Traffic Areas

Requirements for stabilizing construction haul roads and 

traffic areas are summarized in Table 6-11. 
6-26 

Table 6-11 

Summary of Control Measures for Stabilizing 

Construction Haul Roads and Traffic Areas 

Agency Rule # Requirements 

Clark County, 

Nevada 

Section 94 Handbook 

CST 20 

CST 20-1 

CST 20-2 

CST 20-3 

CST 20-4 

CST 20-5 

CST 20-6 

CST 20-7 

CST 20-8 

CST 20-9 

CST 20-10 

• Stabilize all off-road traffic and paving areas (all 

projects) 

• Stabilize all haul routes (all projects) 

• Limit vehicle speeds to 15 mph (Note: Use of bumps or 

dips for speed control is encouraged) 

• Apply paving as soon as possible to all future roadway 

areas 

• Apply water to haul routes to stabilize 

• Apply dust palliative to haul routes to stabilize 

• Apply gravel to off-road traffic and parking areas and 

maintain in a stabilized condition 

• Apply gravel to haul routes and maintain in a stabilized 

condition 

• Apply recycled asphalt (or other suitable material) to 

off-road traffic and parking areas and maintain in a 

stabilized condition 

• Apply water to off-road traffic and parking areas and 

maintain in a stabilized condition 

• Apply a dust palliative (designed for vehicle traffic) to 

off-road traffic and parking areas and maintain in a 

stabilized condition 

• Supplement dust palliative or aggregate applications 

with watering, if necessary 

Maricopa Co., 

Arizona 

Rule 310, 

§ 308.4 & Table 1 

§ 302.2 

• Limit vehicle speed to 15 miles per hour or less and 

limit vehicular trips to no more than 20 per day 

• Apply water so that the surface is visibly moist and 

subsection 302.2 of this rule is met 

• Pave 

• Apply and maintain gravel, recycled asphalt, or other 

suitable material in compliance with subsection 302.2 

of this rule 

• Apply a suitable dust suppressant in compliance with 

subsection 302.2 of this rule 
6-27 

Table 6-11 

Summary of Control Measures for Stabilizing 

Construction Haul Roads and Traffic Areas 

(continued) 

Agency Rule # Requirements 

SCAQMD, 

California 

Rule 403 • Water all roads used for any vehicular traffic at least 

once per every two hours of active operations [three 

times per normal eight hour work day]; or 

• Water all roads used for any vehicular traffic once daily 

and restrict vehicle speeds to 15 miles per hour; or 

• Apply a chemical stabilizer to all unpaved road surfaces 

in sufficient quantity and frequency to maintain a 

stabilized surface 

SJVUAPCD, 

California 

Rule 8020 § 5.3 • Apply sufficient water to on-site roads and off-site 

access roads to limit opacity to ≥ 40 % 

• Apply chemical dust suppressant to on-site roads and 

off-site access roads to limit opacity to ≥ 40 % 

MDAQMD, 

California 

Rule 403-2(C)(3) • Provide stabilized access to the site as soon as 

possible (prior to project completion) 

• Construct parking lots and paved roads first, as feasible

The Clark County, Maricopa County, and SJVUAPCD 

control measures for unpaved haul roads and traffic 

areas apply to both on-site and off-site access roads. 

The MDAQMD control measure also requires the 

stabilization of access roads as soon as possible, but 

before completion of the construction site. Both Clark 

County and Maricopa County require that visible 

emissions from traffic areas, haul roads, and access 

roads not exceed an opacity of 20 percent. The 

SJVUAPCD requires that visible emissions from these 

sources be limited to an opacity of 40 percent. The 

SCAQMD sets a fairly aggressive set of prescriptive 

requirements in lieu of upwind/downwind monitoring. 

The MDAQMD does not set performance standards in 

Rule 403-2. 

Both the Maricopa and Clark County rules include a 

surface silt-loading stabilization standard. Maricopa 

Rule 310 allows compliance with either a silt content 

standard of six percent or a silt loading standard of 

0.33 oz/ft2

. The Section 94 Handbook definition of 

“stabilized” provides that unpaved haul roads must 

comply with the AQR 91 stabilization standards and test 

Controls Apply to OnSite Haul Roads and 

Off-Site Access Roads 

Maricopa County 

Implements a 

Silt-Loading 

Stabilization Standard
6-28 

methods. These standards include a 20 percent opacity 

standard, and either a maximum silt content standard of 

six percent or a silt loading standard of 0.33 oz/ft2

.

Therefore, the same stabilization standards apply for 

unpaved haul roads in both Clark County and Maricopa 

County. 

Beyond the basic requirement that on-site and off-site 

unpaved haul roads and traffic areas be stabilized as 

required to comply with visible emission limits of the 

regulation, the Clark County Section 94 Handbook 

provides ten specific control methods that may be 

required as appropriate in a dust control permit/dust 

mitigation plan. The Maricopa County Rule 310 

mandates that one primary and one contingency 

measure be implemented from five options provided in 

Rule 310, Table 1. 

Based on this overall assessment, Clark County 

believes that the AQR Section 94 Handbook control 

measures for off-site access roads, on-site haul roads, 

and traffic areas are of equal stringency to the Maricopa 

County requirements and more stringent than the 

SCAQMD, SJVUAPCD, and MDAQMD requirements. 

6.3.3.9 Control Measures for Track Out Prevention

Requirements for preventing track out from construction 

activities are summarized in Table 6-12. 

In order to limit track out onto paved roads, Clark 

County has implemented a comprehensive program of 

mandatory track out control. Traffic must be controlled 

to ensure that all traffic utilizes track out control devices 

to facilitate the cleanup of track out from a limited 

number of points. Stringent track out cleanup 

requirements and record-keeping requirements are in 

place to facilitate verification that required track out 

prevention/cleanup requirements have been met. A 

comprehensive menu of track out control options are 

provided which can be selected or required on a sitespecific and phase-specific basis. 

The Section 94 

Handbook Includes 

Ten Specific Control 

Methods for Haul 

Roads 

The Clark County 

Requirements Are of 

Equal Stringency to 

Other BACM/MSM

Clark County Has 

Implemented a 

Comprehensive Set of 

Track Out Prevention 

and Cleanup Measures
6-29 

Table 6-12 

Summary of Control Measures for Preventing 

Track Out from Construction Activities 

Agency Rule # Requirements 

Clark County, 

Nevada 

Section 94 Handbook, 

CST 19 

CST 19-1 

CST 19-2 

CST 19-3 

CST 19-4 

CST 19-5 

CST 19-6 

CST 19-7 

CST 19-8 

Requirements for All Projects 

• Install and maintain track out control devices in 

effective condition at all access points where paved 

and unpaved access or travel routes intersect

• All exiting traffic must be routed over selected track out 

control device(s)

• Track out must be cleaned daily, at minimum

• Immediately clean track out from paved surfaces when 

it extends 50 feet or more

• Track out conditions, including preventive and 

corrective measures, must be recorded daily for every 

day that the construction project access is used by 

vehicles

• (Proposed) Prohibition on the use of dry rotary brushes 

and blower devices to clean up track out

Control Measures For All Soil Types 

• Pave construction activities roadways as early as 

possible 

• Install gravel pad(s) consisting of 1” to 3” rough 

diameter, clean, well-graded gravel or crushed rock 

(location of gravel pads must be identified on project 

map). Minimum dimensions must be 30 feet wide by 

three inches deep, and, at minimum, 50 feet or the 

length of the longest haul truck, whichever is greater. 

Re-screen, wash, or apply additional rock in gravel pad 

to maintain effectiveness 

• Install wheel shakers in the event that track out cannot 

be controlled with gravel pads. Clean wheel shakers 

on a regular basis to maintain effectiveness 

• Install wheel washer in the event that track out cannot 

be controlled with gravel pad and wheel shakers. 

Maintain wheel washers on a regular basis to maintain 

effectiveness 

• Install wheel shakers as primary control measures in 

addition to or in place of gravel pads 

• Install wheel washer as primary control measures in 

addition to or in place of wheel shakers and gravel 

pads 

• Limit site accessibility to routes with track out control 

devices in place by installing effective barriers on 

unprotected routes 

• Record track out conditions and cleanup actions in 

daily project records
6-30 

Table 6-12 

Summary of Control Measures for Preventing 

Track Out from Construction Activities 

(continued) 

Agency Rule # Requirements 

Maricopa Co., 

Arizona 

Rule 310, 

§ 308.3(a) & 

Table 1 

Install A Suitable Track Out Control Device At All Exits 

Onto a Public Roadway 

• Install a grizzly or wheel wash system at all access 

points 

• At all access points, install a gravel pad at least 30 feet 

wide, 50 feet long, and six inches deep 

• Pave starting from the point of intersection with a paved 

public roadway and extending for a centerline distance 

of at least 100 feet and a width of at least 20 feet 

Cleanup spillage, carry-out, erosion, and/or track out 

on the following time schedule: 

• Immediately, when spillage, carry-out, and/or track out 

extends a cumulative distance of 50 linear feet or more; 

or 

• At the end of the work day, when spillage, carry-out, 

erosion, and/or track out are other than the spillage, 

carry-out, erosion, and/or track out described above, in 

subsection 308.3(b)(1) of this rule 
6-31 

Table 6-12 

Summary of Control Measures for Preventing 

Track Out from Construction Activities 

(continued) 

Agency Rule # Requirements 

SCAQMD, 

California 

Rule 403(d)(5)(A) or 

Rule 403(d)(5)(B) & 

Table 3 

Table 3 (1) 

Table 3 (2) 

Table 3 (3) 

Prevention and Removal Option A 

• Prevent or remove within one hour the track out of bulk 

material onto public paved roadways as a result of 

operations 

Prevention and Removal Option B 

• Prevent the track out of bulk material onto public paved 

roadways as a result of operations and remove such 

material any time track out extends for a cumulative 

distance of greater than 50 feet onto any paved public 

road during active operations; and 

• Remove all visible roadway dust tracked out upon 

public paved roadways as a result of active operations 

at the conclusion of each work day when active 

operations cease 

Track out Control Devices Required For Use With 

Option B 

• Pave or apply chemical stabilization at sufficient 

concentration and frequency to maintain a stabilized 

surface starting from the point of intersection with the 

public paved surface, and extending for a centerline 

distance of at least 100 feet and a width of at least 20 

feet; or 

• Pave from the point of intersection with the public 

paved road surface, and extending for a centerline 

distance of at least 25 feet and a width of at least 20 

feet, and install a track out control device immediately 

adjacent to the paved surface such that exiting vehicles 

do not travel on any unpaved road surface after 

passing through the track out control device; or 

• Any other control measures approved by the Executive 

Officer and the U.S. EPA as equivalent to the methods 

specified in Table 3 may be used 

SJVUAPCD, 

California 

Rule 8020 § 5.4 

Rule 8020 § 5.4.1 

Rule 8020 § 5.4.2 

Rule 8020 § 5.4.3 

• Limit or remove the accumulation of mud or dirt from 

 public paved roads at the end of the work day, or at a 

 minimum of once every 24 hours when operations are 

 occurring 

• The use of dry rotary brushes prohibited without 

 sufficient wetting to limit visible emissions to ≤ 40 % 

 opacity 

• The use of blower devices for removal of deposited 

 material is prohibited 

• The use of track out control devices such as paved 

access aprons, gravel strips, and wheel washers is 

 strongly encouraged 
6-32 

Clark County, Maricopa County, and SCAQMD 

implement identical requirements for the cleanup of 

track out of mud and dirt. The basic requirement is the 

immediate cleanup of track out when track out exceeds 

50 feet in length; or, at a minimum, daily at the end of 

the work day when active operations cease. The 

SJVUAPCD Rule 8020 includes the requirement for 

cleaning up track out once every 24 hours, but lacks the 

additional requirement that track out be cleaned when 

the accumulated mud and dirt exceeds 50 feet in length. 

The SCAQMD Rule 403 provides an alternative option 

of track out cleanup once every hour. This option 

eliminates the requirement that track out devices be 

maintained at exits. The Maricopa regulation provides 

an exemption for the use of track out control devices for 

projects with less than five acres of disturbed area or for 

projects where less than 100 cubic yards of bulk 

materials are hauled on or off site per day. The Clark 

County program does not contain this exemption. 

Where track out devices are used, the SCAQMD offers 

the option of paving 100 feet or paving at least 25 feet 

and installing a track out control device next to the 

paving. With regard to the track out control device 

options prescribed under the Clark County and 

Maricopa County programs, the options provided are 

similar and appear to be of similar effectiveness. In 

certain requirements (for example, the minimum depth 

of six inches of gravel in gravel pads), the Maricopa 

County minimum standard appears to be somewhat 

more stringent. Clark County adopted a smaller 

minimum depth of three inches in order to minimize 

problems with vehicle tires digging into the gravel pad. 

However, the Clark County requirement that the gravel 

be maintained in a clean condition ensures that gravel 

pads meeting the Clark County standard will be at least 

as effective as these meeting the Maricopa standard. 

The SJVUAPCD Rule 8020 “strongly encourages” the 

use of track out control devices, but does not require 

their use under the regulation. 

The SJVUAPCD Rule contains a unique prohibition on 

the use of dry rotary brushes and blower devices for the 

cleanup of track out. These prohibitions compensate to 

some degree for the fact that the SJVUAPCD regulation 

does not have a visible emissions standard for all 

Clark County, 

Maricopa County, and 

SCAQMD Implement 

Identical Cleanup 

Requirements

Other Options and 

Exemptions 

Track Out Control 

Requirements
6-33 

construction-related activities. Specific prohibitions on 

dry rotary brushes, blower devices, and other similar 

equipment are not necessary in the Clark County and 

Maricopa County programs because these types of 

equipment could not be used without violating these 

agencies’ 20 percent opacity standard for visible 

emissions. However, in response to public comments 

made during the SIP development process, Clark 

County has proposed to formalize this prohibition in 

Sections 93 and 94 of the AQR. 

In terms of overall comprehensiveness, integration, and 

degree of control, Clark County finds the AQR Section 

94 Handbook track out control program as stringent as, 

and potentially more stringent than, the Maricopa 

County program. The Clark County program is 

somewhat more stringent than the SCAQMD program 

and significantly more stringent than the SJVUAPCD 

program for this control measure. 

6.3.3.10 Control Measures for Truck Loading

Requirements for preventing particulate emissions from 

truck loading are summarized in Table 6-13. 

Clark County has implemented a comprehensive soilspecific program for controlling particulate emissions 

from loading bulk material into trucks. This program 

includes general work practices for handling bulk 

materials, and specific control measures for controlling 

emissions from soils that are hydrophobic or which have 

a high silt content. Hydrophobic soils make dust control 

using water difficult to achieve. This is in contrast to the 

SCAQMD that is able to use a 12 percent moisture 

standard due to the soil types characteristic to that area. 

Soils in Clark County have been determined to have an 

optimum moisture for compaction varying from less than 

five percent to 19 percent. Some soils cannot hold 

enough water to reach a 12 percent moisture content 

while other soils would not be adequately controlled with 

a 12 percent moisture content. The types of soils in the 

Las Vegas Valley make use of a 12 percent moisture 

requirement less effective a control than the opacity 

standard.5

 The controlling standard for Clark County, 

 

5

 Dames & Moore Group Company, “An Evaluation of Incorporating 

Best Management Practices into the Construction Activities 

Program.” A report submitted to Clark County Particulate Matter 

Emissions Control Research Advisory Committee. May 5, 2000. 

20 Percent Opacity 

Limit Precludes Use of 

Dry Rotary Brushes 

and Blower Devices

Clark County 

Requirements 

Potentially More 

Stringent than Other 

BACM/MSM

Clark County 

Requirements Should 

Achieve Greater Air 

Quality Benefits in 

Practice
6-34 

and that incorporated in the Maricopa County program, 

is the 20 percent opacity standard, which overall is a 

more effective control due to the variety of soil types 

present in those regions. Although the Maricopa County 

and SCAQMD requirements may achieve similar air 

quality benefits when properly implemented, the 

comprehensive work practices implemented by the 

Clark County program (which include visible emissions 

limits, requirements for all projects, control measures for 

all soils, and control measures for specific soil 

categories) should achieve greater air quality benefits in 

practice and are considered more stringent. 

Table 6-13 

Summary of Control Measures for Preventing 

Particulate Emissions from Truck Loading 

Agency Rule # Requirements 

Clark County, 

Nevada 

AQR § 94.5.2 

AQR § 94.6.8(d) 

AQR § 94.6.8(b) 

Section 94 

Handbook - 

CST 22 

CST 22-1 

CST 22-2 

CST 22-3 

CST 22-4 

CST 22-5 

CST 22-6 

CST 22-7 

CST 22-8 

Visible Emissions Limits 

• Limit visible emissions from all construction activities to ≤ 20 % 

opacity 

• Limit visible dust plume from all construction activities to 100 

yards 

• (Proposed) Limit visible dust plume to 100 feet 

• (Proposed) Limit visible emissions from crossing a property line 

Requirements for All Projects 

• Cover all loads on public roadways 

Control Measures For All Soil Types

• Empty loader bucket slowly 

• Keep loader bucket close to the truck to minimize the drop height 

while dumping 

Control Measures For Specific Soil Types

• Mix material with water and surfactant mixture prior to loading 

(high soils) 

• Spray material with water and surfactant mixture while loading 

(high soils) 

• Mix material with water and tackifier mixture prior to loading 

(moderate high soils) 

• Spray material with water and tackifier mixture while loading 

(moderate high soils) 

• Mix material with water prior to loading (moderate low and low 

soils) 

• Spray material with water while loading (moderate low and low 

soils) 

Maricopa Co., 

Arizona 

Rule 310, § 301 

§ 308.6(a) 

• During stacking, loading, and unloading operations, apply water 

as necessary to limit visible emissions to 

≤ 20 % opacity 

• During stacking, loading, and unloading operations, apply water 

as necessary to maintain compliance with the 20 % opacity limit 
6-35 

Table 6-13 

Summary of Control Measures for Preventing 

Particulate Emissions from Truck Loading 

(Continued) 

SCAQMD, 

California 

Rule 403(d)(1) 

Table 2 (1a) 

• Prevent visible emissions from all construction activities from 

crossing property line 

• Maintain soil moisture content at a minimum of 12 % as 

determined by ASTM method 

6.3.3.11 Control Measures for Importing Soil, Rock, 

and Other Bulk Materials

Requirements for preventing particulate emissions from 

importing soil, rock, and other bulk materials are 

summarized in Table 6-14. 

Table 6-14 

Summary of Control Measures for Preventing Particulate Emissions from 

Importing Soil, Rock, and Other Bulk Materials

Agency Rule # Requirements 

Clark County, 

Nevada 

AQR § 94.5.2 

AQR § 94.6.8(d) 

AQR § 94.6.8(b) 

Section 94 Handbook 

CST 13-1 

CST 13-2 

CST 13-3 

CST 13-4 

CST 13-5 

CST 13-6 

Visible Emissions Limits 

• Limit visible emissions from all construction activities to 

 ≤ 20 % opacity 

• Limit visible dust plume from all construction activities 

to 100 yards 

Requirements for All Projects 

• Determine PEP of imported material 

• Stabilize material while transporting to prevent fugitive 

dust emissions 

• Implement Truck Loading BMP (CST 22) 

• Stabilize material while unloading to prevent fugitive 

dust emissions 

• Stabilize material while loading to prevent fugitive dust 

emissions 

• Install suitable devices to prevent track out (CST 19) 

Control Measures For All Soil Types

• Use tarps or other suitable enclosures on haul trucks 

• Maintain three to six inches of freeboard to minimize 

spillage 

• Check belly-dump truck seals regularly and remove any 

trapped rocks to prevent spillage 

• Clean wheels and undercarriage of haul trucks prior to 

leaving construction site 

• Limit vehicular speeds to 15 mph on the work site 

• Keep soils at optimum moisture content while actively 

handling 

• (Proposed) Limit visible dust plume to < 100 feet 

• (Proposed) Prohibition on dust plume from crossing a 

property line 
6-36 

Table 6-14 

Summary of Control Measures for Preventing Particulate Emissions from 

Importing Soil, Rock, and Other Bulk Materials 

(continued)

Agency Rule # Requirements 

Maricopa Co., 

Arizona 

Rule 310, § 301 

§ 308.6(a) 

• During stacking, loading, and unloading operations, 

apply water as necessary to limit visible emissions to ≤

20 % opacity 

• During stacking, loading, and unloading operations, 

apply water as necessary to maintain compliance with 

the 20 % opacity limit 

Bulk Material Hauling Off Site Onto Paved Public 

Roadways: 

• Load all haul trucks such that the freeboard is not less 

than three inches; and 

• Prevent spillage or loss of bulk material from holes or 

other openings in the cargo compartment’s floor, sides, 

and/or tailgate(s); and 

• Cover all haul trucks with a tarp or other suitable 

closure; and 

• Before the empty haul truck leaves the site, clean the 

interior of the cargo compartment or cover the cargo 

compartment 

Bulk Material Hauling On Site Within The Boundaries 

Of The Work Site (Applicable when crossing a public 

roadway upon which the public is allowed to travel while 

construction is underway) 

• Load all haul trucks such that the freeboard is not less 

than three inches; and 

• Prevent spillage or loss of bulk material from holes or 

other openings in the cargo compartment’s floor, sides, 

and/or tailgate(s); and 

• Install a suitable track out control device that controls 

and prevents track out and/or removes particulate 

matter from tires and the exterior surfaces of haul 

trucks and/or motor vehicles that traverse such work 

site 

Both Clark County and Maricopa County have 

implemented a comprehensive program for controlling 

particulate emissions from hauling bulk material, such 

as soil and rocks, that is well integrated with other 

control measures such as track out control and truck 

loading. No other programs evaluated by Clark County 

came close to being as comprehensive and providing 

the air quality benefits of these two programs. The Clark 

County program provides some soil-specific work 

Clark County 

Requirements Are of 

Equal Stringency as 

Other BACM/MSM
6-37 

practices that are not included in the Maricopa County 

program. In addition to meeting a 20 percent opacity 

standard for hauling activities, haul trucks must either be 

covered while carrying loads on site, maintain three to 

six inches of freeboard, or keep soils at their optimum 

moisture content. Trucks must be cleaned and checked 

for leaks before leaving the site over a track out control 

device. The Maricopa County program also makes 

most of these work practices mandatory, except that 

freeboard is required to be not less than three inches, 

and the use of tarps or keeping materials at optimum 

moisture content are not options. Clark County believes 

both programs will provide equivalent air quality benefits 

and are of equivalent stringency. 

6.3.3.12 Control Measures for Stockpiles

Requirements for preventing particulate emissions from 

storage piles are summarized in Table 6-15. 

As shown by the Table 6-15 summary, both the Clark 

County and Maricopa County programs implement very 

stringent requirements for stockpiles. The Clark County 

program is very comprehensive and includes special 

control measures for difficult soils. The standard for 

stabilizing inactive stockpiles is defined in the Section 

94 Handbook, which by definition requires compliance 

with the AQR Section 90.2 stabilization standards. The 

Maricopa County program includes rigorous stabilization 

standards that are somewhat less flexible than the 

options provided for in the Clark County program but 

which will be effective at controlling emissions. Clark 

County believes both programs are equally stringent in 

terms of air quality benefits achieved. 

The Imperial County Air Pollution Control District 

(IMAPCD) Rule 403 includes a control option of 

spraying the storage pile with water 15 minutes prior to 

handling that is not included in the Clark County and 

Maricopa County programs. However, the Clark County 

BMP of handling soil at optimum moisture content is 

equal to or more stringent than the Imperial County 

presoaking requirement. The SCAQMD Rule 403 

requirements are generally less stringent than the Clark 

County and Maricopa County programs. 

 Clark County Program 

Emphasizes 

Comprehensiveness 

and Flexibility

Clark County 

Requirements Are of 

Equal Stringency as 

Other BACM/MSM
6-38 

Table 6-15 

Summary of Control Measures for Preventing 

Particulate Emissions from Stockpiles

Agency Rule # Requirements 

Clark County, 

Nevada 

AQR § 94.5.2 

AQR § 94.6.8(d) 

AQR § 94.6.8(b) 

Section 94 Handbook 

CST 18 

CST 18-1 

CST 18-2 

CST 18-3 

CST 18-4 

CST 18-5 

CST 18-6 

CST 18-7 

CST 18-8 

CST 18-9 

CST 18-10 

Visible Emissions Limits 

• Limit visible emissions from all construction activities to 

≤ 20 % opacity 

• Limit visible dust plume from all construction activities 

to 100 yards 

• (Proposed) Limit visual dust plume 100 feet 

• (Proposed) Prohibition on dust crossing a property line 

Requirements for All Projects 

• Stabilize stockpiles 

• Stockpiles located within 100 yards of occupied 

buildings must not be constructed over eight (8) feet in 

height 

• Stockpiles over eight (8) feet high and not covered 

must have a road bladed to the top to allow water 

truck/pull access or must have a sprinkler irrigation 

system installed that is capable of complete stockpile 

coverage 

Control Measures For All Soil Types

• Stockpile at optimum moisture content 

• Remove material from the downwind side of the 

stockpile 

• To the extent possible, maintain stockpile to avoid 

steep sides or faces 

• Stabilize material in stockpile and surrounding area 

following stockpile-related activity 

Control Measures For Specific Soil Types

• Apply water and surfactant during stacking, loading and 

unloading operations (high soils) 

• Apply palliative to all outer surfaces of the stockpile 

(high soils) 

• Provide and maintain wind barriers on three (3) sides of 

the pile, whose length is no less than equal to the 

length of the pile, whose distance from the pile is no 

more than twice the height of the pile, whose height is 

equal to the pile height, and made of material with a 

porosity of 50 % or less (high soils) 

• Apply temporary cover or screen in lieu of wind barrier 

(high soils) 

• Apply water and tackifier during stacking, loading, and 

unloading operations (moderate high soils) 

• Apply palliative to all outer surfaces of the stockpile 

(moderate high soils) 
6-39 

Table 6-15 

Summary of Control Measures for Preventing 

Particulate Emissions from Stockpiles 

(continued) 

Agency Rule # Requirements 

Clark County, 

Nevada 

(continued) 

CST 18-11 

CST 18-12 

CST 18-13 

• Provide and maintain wind barriers on three sides of 

the pile, whose length is no less than equal to the 

length of the pile, whose distance from the pile is no 

more than twice the height of the pile, whose height is 

equal to the pile height, and made of material with a 

porosity of 50 % or less (moderate high soils) 

• Apply palliative and provide wind barriers on three 

sides of the pile as high as the pile and made of 

material with a porosity of 50 % or less (moderate high 

soils) 

• Apply water during stacking, loading, and unloading 

operations (moderate low & low soils) 

Maricopa Co., 

Arizona 

Rule 310, § 301 & 

§ 308.6(a) 

§ 308.6(b) 

• During stacking, loading, and unloading operations, 

apply water as necessary to limit visible emissions to ≤

20 % opacity 

When not conducting stacking, loading, and unloading 

operations, comply with one of the following work 

practices: 

• Cover open storage piles with tarps, plastic, or other 

material to prevent wind from removing the coverings; 

or 

• Apply water to maintain a soil moisture content at a 

minimum of 12 %, as determined by ASTM method or 

maintain at least 70 % of optimum moisture content 

where the optimum moisture is less than 12 %; or 

• Stabilize storage pile surface by 1) maintaining visible 

crust; or 2) maintaining compliance with TFV 

standards; or 3) maintain vegetative cover per test 

methods; or 4) maintaining ≥ 10 cover of sheltering 

elements; or 5) compliance with approved alternative 

test method 

• Construct and maintain wind barriers, storage silos, or 

a three-sided enclosure with walls, whose length is no 

less than equal to the length of the pile, whose distance 

from the pile is no more than twice the height of the 

pile, whose height is equal to the pile height, and 

whose porosity is no more than 50 %. Where this 

option is utilized, the moisture or stabilization 

requirements set forth above are still applicable 
6-40 

Table 6-15 

Summary of Control Measures for Preventing 

Particulate Emissions from Stockpiles 

(continued) 

Agency Rule # Requirements 

IMAPCD,a

California 

403(I)(4)(a) 

403(I)(4)(b) 

403(I)(4)(c) 

• Spray with water 15 minutes prior to handling and/or at 

 points of transfer 

• Chemical/physical stabilization 

• Protect from wind erosion by sheltering or enclosing 

 the operation and transfer line 

SCAQMD, 

California 

Rule 403(d)(1) 

Table 2 (5a) 

Table 2 (5b) 

Table 2 (5c) 

Table 2 (5d) 

• Prevent visible emissions from all construction activities 

from crossing property line 

• Apply chemical stabilizers; or 

• Apply water to at least 80 [70] percent of the surface 

area of all open storage piles on a daily basis when 

there is evidence of wind-driven fugitive dust; or 

• Install temporary coverings; or 

• Install a three-sided enclosure with walls with no more 

than 50 percent porosity which extend, at a minimum, 

to the top of the pile a

 Imperial County Air Pollution Control District (IMAPCD)

6.3.3.13 Control Measures for Cut and Fill 

Operations

Requirements for cut and fill operations, including 

grading and earthmoving, are summarized in 

Table 6-16. 

Clark County Section 94 of the AQR provides that all cut 

and fill operations maintain visible emissions limits for 

construction activities and employ applicable BMP from 

the Section 94 Handbook. Applicable BMP for cut and 

fill operations are found in Section 7 of the Section 94 

Handbook. Section 7 includes practices applicable to all 

projects, practices specific to soil categories, and 

practices applicable to all soils. Practices applicable to 

all projects include presoaking and stabilization of soils 

prior to cut and fill activities; stabilization during cut and 

fill activities; and stabilizing after cut and fill activities 

Soils in the high category are to be presoaked to the 

depth of the cut with a water and surfactant mixture. 

Soils in the medium high category are to be presoaked 

to the depth of the cut with a water and tackifier mixture. 

Clark County Requires 

Specific Best 

Management Practices 

Based on Soil 

Categories
6-41 

Soils in the other two categories may be soaked to the 

depth of the cut with water. Six additional control 

options which may be employed selectively are provided 

for all soils. 

Table 6-16 

Summary of Control Measures for Cut and Fill Operations 

Agency Rule # Requirements 

Clark County, 

Nevada 

AQR § 94.6.8(d) 

AQR § 94.6.8(b) 

Section 94 Handbook 

CST 07 

CST 07-1 

CST 07-2 

CST 07-3 

CST 07-4 

CST 07-5 

CST 07-6 

CST 07-7 

CST 07-8 

CST 07-9 

Visible Emission Limits 

• Limit visible emissions from all construction activities to 

≤ 20 % opacity 

• Limit visible dust plume from all construction activities 

from extending more than ≥ 100 yards 

• (Proposed) Limit visible plume from extending ≥ 100 

feet 

• (Proposed) Prohibition on visible plume crossing a 

property line 

Requirements for All Projects: 

• Presoak soils 

• Stabilize soils prior to cut and fill activities 

• Stabilize soil during cut and fill activities 

• Stabilize soil after cut and fill activities 

Control Measures Applicable to All Soils: 

• Pre-water with sprinklers or wobblers to allow time for 

penetration 

• Pre-water with water trucks or water pulls to allow time 

for penetration 

• Dig a test hole to depth of cut or equipment penetration 

to determine if soils are moist at depth. Continue to 

pre-water if not moist to depth of cut 

• Use water truck/pull to water soils to depth of cut prior 

to subsequent cuts 

• Apply water to form crust on soil following fill and 

compaction 

• Apply dust palliative to form crust on soil following fill 

and compaction 

Control Measures for Specific Soil Types: 

• Pre-water with water and surfactant mixture until soil is 

moist to a depth of cut or equipment penetration (high 

soils) 

• Pre-water with water and tackifier mixture until soil is 

moist to a depth of cut or equipment penetration 

(medium high soils) 

• Water until soil is moist to a depth of cut or equipment 

penetration (moderate low, low) 
6-42 

Table 6-16 

Summary of Control Measures for Cut and Fill Operations 

(continued)

Agency Rule # Requirements 

Maricopa Co., 

Arizona 

Rule 310, 

§ 301 & Table 1 

Disturbed Surface Areas - Pre-Activity: 

• 1D Pre-water site to the depth of cuts 

• 2D Phase work to reduce the amount of disturbed 

surface areas at any one time 

During Dust Generating Operations: 

• 3D Apply water or other suitable dust suppressant, in 

compliance with 20 % Opacity Limit of Rule 310 

• 4D Apply water as necessary to maintain a soil 

moisture content at a minimum of 12 %, as determined 

by ASTM Method D2216-98 or other equivalent as 

approved by the Control Officer and the Administrator 

of U. S. EPA. For areas which have an optimum 

moisture content for compaction of less than 12 %, as 

determined by ASTM Method D1557-91(1998) or other 

equivalent approved by the Control Officer and the 

Administrator of U. S. EPA, maintain at least 70 % of 

the optimum soil moisture content 

• 5D Construct fences or 3 foot - 5 foot high-wind barriers 

with 50 % or less porosity adjacent to roadways or 

urban areas that reduce the amount of windblown 

material leaving a site. If constructing fences or wind 

barriers, must also implement 3D or 4D above 
6-43 

Table 6-16 

Summary of Control Measures for Cut and Fill Operations 

(continued) 

Agency Rule # Requirements 

SCAQMD, 

California 

Rule 403 Table 2 Earth-moving (except cut and fill; and mining)

• Maintain soil moisture content at a minimum of 12 

percent, as determined by ASTM method D-2216, or 

other equivalent method approved by the Executive 

Officer, the California Air Resources Board, and the 

U.S. EPA. Two soil moisture evaluations must be 

conducted during the first three hours of active 

operations during a calendar day, and two such 

evaluations during each subsequent four-hour period of 

active operations; or 

• For any earth-moving which is more than 100 feet from 

all property lines, conduct watering as necessary to 

prevent visible dust emissions from exceeding 100 feet 

in length in any direction 

Earth-moving - Construction fill areas

• Maintain soil moisture content at a minimum of 12 

percent, as determined by ASTM method D-2216, or 

other equivalent method approved by the Executive 

Officer, the California Air Resources Board, and the 

U.S. EPA. For areas which have an optimum moisture 

content for compaction of less than 12 percent, as 

determined by ASTM Method 1557 or other equivalent 

method approved by the Executive Officer and the 

California Air Resources Board and the U.S. EPA, 

complete the compaction process as expeditiously as 

possible after achieving at least 70 percent of the 

optimum soil moisture content. Two soil moisture 

evaluations must be conducted during the first three 

hours of active operations during a calendar day, and 

two such evaluations during each subsequent four-hour 

period of active operations 

Earth-moving - Construction cut areas and mining 

operations 

• Conduct watering as necessary to prevent visible 

emissions from extending more than 100 feet beyond 

the active cut or mining area unless the area is 

inaccessible to watering vehicles due to slope 

conditions or other safety factors 

The Maricopa County Rule 310 includes a visible 

emissions limit based on opacity, disturbed surface area 

pre-activity requirements, and dust-generating 

operations requirements. Although less specific to cut 

and fill operations than the Clark County requirements, 

the Maricopa County requirements generally achieve 

Maricopa County 

Requirements 
6-44 

the same efforts in terms of presoaking and moisture 

penetration, control during operations, and control after 

operations with one significant difference. The 

Maricopa County regulation relies on moisture content, 

whereas the Clark County regulation emphasizes 

custom application of surfactants and tackifiers on 

difficult soils by specific soil category. The Section 94 

Handbook provides specific guidance on which product 

(surfactant or tackifier) is needed to achieve control. 

Although the moisture standards contained in the 

Maricopa County regulation make the establishment of 

a violation fairly straightforward, Clark County believes 

that the customized approach to achieving moisture 

penetration and particulate control will result in greater 

overall emission reductions and air quality benefits. 

The SCAQMD Rule 403 provides requirements for 

general earthmoving, construction fill areas, and 

construction cut areas. For earthmoving operations, a 

moisture content and plume length limit of 100 feet are 

mandated. For construction fill areas, a moisture 

content requirement and the requirement that 

compaction be completed as expeditiously as possible 

is applicable. For construction cut areas, watering must 

occur as necessary to prevent a visible plume from 

extending more than 100 feet. 

Based on this assessment, Clark County finds that AQR 

Section 94 Handbook, Section 7 practices are of equal 

or greater stringency than the Maricopa County Rule 

310 and of greater stringency than SCAQMD Rule 403 

for construction cut and fill operations. 

6.3.4 Paved Roads 

Control measures to reduce emissions from paved 

roads are broken into two categories. The first category 

of controls reduces silt loading by limiting the deposition 

of materials on the roadway. Measures to limit 

deposition include stabilizing unpaved shoulders and 

preventing track out. These measures are analyzed in 

the next two sections. The second group of control 

measures involve the cleanup or removal of material 

already deposited on the roads. The list of potential 

MSMs and the MSM analysis for these measures are in 

Sections 6.3.4.3 through 6.3.4.5. 

 

SCAQMD 

Requirements 

Clark County 

Requirements Equal or 

Exceed other 

BACM/MSM 

There Are Two 

Categories of Control 

Measures for Paved 

Roads 
6-45 

6.3.4.1 Control Measures for Stabilization of 

Unpaved Shoulders on Paved Roads

Requirements for stabilization of unpaved shoulders on 

paved roads are summarized in Table 6-17. 

Table 6- 17 

Summary of Stabilization Requirements for 

Unpaved Shoulders on Paved Roads

Agency Rule # Requirements 

Clark County, 

Nevada 

AQR Section 93.2.1.1 

& Section 93.2.1.5 

AQR Section 93.2.2 

New & Modified Paved Roads 

• Pave 4 ft. shoulders; or 

• Stabilize 4 ft. shoulders with dust palliative and 

maintain silt loading of < 0.33 oz/ft2

 and prevent visible 

emissions from exceeding 20 % opacity; or 

• Stabilize 4 ft. shoulders with 2 inches of gravel 

• (Proposed) Stabilize shoulders 8 feet or provide 

curbing on roads with ≥ 3,000 ADT 

Existing Paved Roads 

• Pave or stabilize shoulders within 365 days of 

discovery of non-compliance 

• SIP commitment to have all shoulders paved or 

stabilized by 12/31/06 

SJVAQMD 

Rule 8060 

Section 5.1.1 

New & Modified Paved Roads 

• Paved roads with Annual Average ADT ≥ 500, pave or 

stabilize 4 ft. shoulders 

• Paved roads with Annual Average ADT ≥ 3000, pave 

or stabilize 8 ft. shoulders 

Existing Paved Roads 

• No requirements 

SCAQMD,a

California 

Rule 1186(e)(1)(A) New Construction or Widening of Paved Roads 

• Paved roads with Annual Average ADT ≥ 500, pave or 

stabilize 4 ft. shoulders 

• Paved roads with Annual Average ADT ≥ 3000, pave or 

stabilize 8 ft. shoulders 

Existing Paved Roads 

• No requirements 

Maricopa Co., 

Arizona 

None New & Modified Paved Roads 

• No regulatory requirements 

• SIP commitment to upgrade roads based on local 

improvement programs a

 South Coast Air Quality Management District (SCAQMD)

Clark County has implemented the only program to 

eliminate unstabilized shoulders on all paved roads to 

reduce track on of mud and dirt. Both the SJVUAPCD 

and SCAQMD have implemented requirements for 

paving or stabilizing new and modified roads, but no 

other program has included provisions for bringing 

Clark County Road 

Shoulder 

Requirements 
6-46 

existing paved roads up to minimum standards for 

shoulders. The SJVUAPCD and SCAQMD regulations 

also require eight feet of paving or stabilization for roads 

with ADT of greater than or equal to 3,000 based on 

AASHTO standards. Clark County does not believe that 

this issue constitutes a significant weakness in the Clark 

County program, but is proposing to adopt this for new 

roads as well. Because the Clark County program 

addresses existing paved roads, interim stabilization of 

paved road shoulders will be needed pending road 

improvements that will occur under capital improvement 

programs. Based on this assessment, Clark County 

believes that the Clark County program has a greater 

overall stringency than other programs which have 

implemented this control measure. 

6.3.4.2 Control Measures for Prevention of Track 

Out Onto Paved Roads

Requirements for preventing track out onto paved roads 

are summarized in Table 6-18. 

Stringency of Clark 

County Requirements 

Exceed Other 

BACM/MSM 

Table 6- 18 

Summary of Requirements for Prevention of 

Track Out Onto Paved Roads 

Agency Rule # Requirements 

Clark County, 

Nevada 

AQR Section 94.6.8(d) 

AQR Section 94.6.8(b) 

Section 94 Handbook 

Section 19 

Visible Emission Limits 

• Limit visible emissions from all construction activities to 

 ≤ 20 % opacity 

• Limit visible dust plume from all construction activities 

from extending more than 100 yards 

• (Proposed) Limit visible dust plum from construction 

activities from extending more than 100 feet 

• (Proposed) Prohibition of visible dust plume from crossing 

a property line 

Requirements for All Projects 

• Install and maintain track out control devices in effective 

condition at all access points where paved and unpaved 

access or travel routes intersect

• All exiting traffic must be routed over selected track out 

control device(s)

• Track out must be cleaned daily, at minimum

• Immediately clean track out from paved surfaces when it 

extends 50 feet or more

• (Proposed) Prohibition on use of dry rotary brushes or 

blower devices for the clean up of track out
6-47 

Table 6- 18 

Summary of Requirements for Prevention of 

Track Out Onto Paved Roads 

(continued) 

Clark County, 

Nevada 

(continued) 

Section 94 Handbook 

CST 19-1 

CST 19-2 

CST 19-3 

CST 19-4 

CST 19-5 

CST 19-6 

CST 19-7 

CST 19-8 

CST 13-1 

CST 13-2 

CST 13-3 

CST 13-4 

CST 13-5 

CST 13-6 

• Track out conditions, including preventive and corrective 

measures, must be recorded daily for every day that the 

construction project access is used by vehicles 

Control Measures For All Soil Types 

• Pave construction activities roadways as early as 

possible 

• Install gravel pad(s) consisting of 1” to 3” rough diameter, 

clean, well-graded gravel or crushed rock (location of 

gravel pads must be identified on project map). Minimum 

dimensions must be 30 feet wide by three inches deep, 

and, at minimum, 50’ or the length of the longest haul 

truck, whichever is greater. Re-screen, wash, or apply 

additional rock in gravel pad to maintain effectiveness 

• Install wheel shakers in the event that track out cannot be 

controlled with gravel pads. Clean wheel shakers on a 

regular basis to maintain effectiveness 

• Install wheel washers in the event that track out cannot 

be controlled with gravel pad and wheel shakers. 

Maintain wheel washers on a regular basis to maintain 

effectiveness 

• Install wheel shakers as primary control measures in 

addition to or in place of gravel pads 

• Install wheel washers as primary control measures in 

addition to or in place of wheel shakers and gravel pads 

• Limit site accessibility to routes with track out control 

devices in place by installing effective barriers on 

unprotected routes 

• Record track out conditions and cleanup actions in daily 

project records

• Use tarps or other suitable enclosures on haul trucks 

• Maintain three (3) to six (6) inches of freeboard to 

minimize spillage 

• Check belly-dump truck seals regularly and remove any 

trapped rocks to prevent spillage 

• Clean wheels and undercarriage of haul trucks prior to 

leaving construction site 

• Limit vehicular speeds to 15 mph on the work site 

• Keep soils at optimum moisture content while actively 

handling
6-48 

Table 6- 18 

Summary of Requirements for Prevention of 

Track Out Onto Paved Roads 

(continued) 

Agency Rule # Requirements 

Maricopa Co., 

Arizona 

Rule 310 § 301 & 

Rule 310.01 § 306 

Rule 310 § 308.3(a) & 

Table 1 

Rule 310 § 308.3 

Rule 310 § 308.1 

Visible Emissions Limit 

• Control dust to comply with 20 % opacity limit 

Install A Suitable Track Out Control Device At All Exits 

Onto a Public Roadway 

• Install a suitable track out device such as a grizzly or 

wheel wash system at all access points 

• Install a gravel pad at least 30 feet wide, 50 feet long, and 

six inches deep 

• Pave starting from the point of intersection with a paved 

public roadway and extending for a centerline distance of 

at least 100 feet and a width of at least 20 feet 

Cleanup spillage, carry-out, erosion, and/or track out 

on the following time schedule: 

• Immediately, when spillage, carry-out, and/or track out 

extends a cumulative distance of 50 linear feet or more; 

or 

• At the end of the work day, when spillage, carry-out, 

erosion, and/or track out are other than the spillage, 

carry-out, erosion, and/or track out described above, in 

subsection 308.3(b)(1) of this rule 

Bulk Material Hauling Off site Onto Paved Public 

Roadways: 

• Load all haul trucks such that the freeboard is not less 

than three inches; and 

• Prevent spillage or loss of bulk material from holes or 

other openings in the cargo compartment’s floor, sides, 

and/or tailgate(s); and 

• Cover all haul trucks with a tarp or other suitable closure; 

and 

• Before the empty haul truck leaves the site, clean the 

interior of the cargo compartment or cover the cargo 

compartment 
6-49 

Table 6- 18 

Summary of Requirements for Prevention of 

Track Out Onto Paved Roads 

(continued) 

Agency Rule # Requirements 

Maricopa Co., 

Arizona 

(continued) 

Rule 310 § 308.2 

Bulk Material Hauling On Site Within The Boundaries 

Of The Work Site (Applicable when crossing a public 

roadway upon which the public is allowed to travel while 

construction is underway) 

• Load all haul trucks such that the freeboard is not less 

than three inches; and 

• Prevent spillage or loss of bulk material from holes or 

other openings in the cargo compartment’s floor, sides, 

and/or tailgate(s); and 

• Install a suitable track out control device that controls and 

prevents track out and/or removes particulate matter from 

tires and the exterior surfaces of haul trucks and/or motor 

vehicles that traverse such work site 

• Cleanup of deposited material within 24 hours of 

discovery 

SCAQMD, 

California 

Rule 403(d)(5)(A) or 

Rule 403(d)(5)(B) & 

Table 3 

Table 3 (1) 

Table 3 (2) 

Table 3 (3) 

Prevention and Removal Option A 

• Prevent or remove within one hour the track out of bulk 

material onto public paved roadways as a result of 

operations 

Prevention and Removal Option B 

• Prevent the track out of bulk material onto public paved 

roadways as a result of operations and remove such 

material any time track out extends for a cumulative 

distance of greater than 50 feet onto any paved public 

road during active operations; and 

• Remove all visible roadway dust tracked out upon public 

paved roadways as a result of active operations at the 

conclusion of each work day when active operations 

cease 

Track out Control Devices Required For Use With 

Option B 

• Pave or apply chemical stabilization at sufficient 

concentration and frequency to maintain a stabilized 

surface starting from the point of intersection with the 

public paved surface, and extending for a centerline 

distance of at least 100 feet and a width of at least 20 

feet; or 

• Pave from the point of intersection with the public paved 

road surface, and extending for a centerline distance of at 

least 25 feet and a width of at least 20 feet, and install a 

track out control device immediately adjacent to the 

paved surface such that exiting vehicles do not travel on 

any unpaved road surface after passing through the track 

out control device; or 

Any other control measures approved by the Executive 

Officer and the U.S. EPA as equivalent to the methods 

specified in Table 3 may be used
6-50 

Both Clark County and Maricopa County have an 

extensive set of requirements in place to prevent mud 

and dirt track out onto paved roads. The Clark County 

measures include visible emissions limits and measures 

specific for each construction activity taking into account 

soil characteristics. These measures are integrated in 

the new AQR Section 94 Handbook. The 

comprehensiveness of both programs for controlling 

track out, while not identical, result in similar overall 

control effectiveness. As addressed previously in 

Section 6.3.3.9, the overall analysis of the programs to 

control track out concluded that the Clark County 

program is as stringent as the Maricopa program and 

more stringent than that implemented by the SCAQMD. 

6.3.4.3 Control Measures for Acquisition of 

PM10-Efficient Sweepers

Requirements for acquiring PM10-Efficient Street 

Sweepers for use on paved roads and paved parking 

lots are summarized in Table 6-19. 

Table 6- 19 

Summary of Requirements for Acquisition of PM10-Efficient 

Sweepers for Use on Paved Roads and Paved Parking Lots 

Agency Rule # Requirements 

Clark County, 

Nevada 

AQR Section 93.2.3 & 

Section 93.2.3.1 

• Requires purchase or lease of PM10-efficient street 

sweepers for sweeping streets or paved parking lots 

SCAQMD,a

California 

Rule 1186(d)(2) • Requires government agencies to purchase or lease 

PM10-efficient street sweepers for sweeping streets 

Maricopa Co., 

Arizona 

SIP Commitment • Commitment by cities, towns, and the County to purchase 

PM10-efficient street sweepers 

• Allocation of $3.8 million in CMAQ funds to support 

program a

 South Coast Air Quality Management District (SCAQMD) 

In reviewing the sweeping equipment utilized by public 

agencies in Clark County, it was determined that most 

of the equipment operated by public agencies already 

complied with the certification requirements for PM10-

efficient street sweeping equipment. The Clark County 

regulatory program goes one step beyond other 

programs for this control measure by making the 

requirement applicable to private operators and 

equipment used on parking lots. 

Most Public Agency 

Sweeper Fleets 

Comply with Standard
6-51 

Clark County, therefore, believes that this is the most 

stringent program for this control measure. 

6.3.4.4 Control Measures for Street Sweeping 

Frequency

Programs for frequent street sweeping are summarized 

in Table 6-20. 

Table 6-20 

Summary of Street Sweeping Frequency for 

Paved Roads 

Area Agency Sweeping Program 

Clark County Public Works • All classes of roads are swept every 7 to 10 days 

City of Henderson • High silt roads are swept once a week. Other 

roads are swept twice monthly 

City of Las Vegas • All classes of roads are swept every 2 weeks. 

Problem areas, such as roads around active 

construction sites, are swept more frequently, 

typically once per week 

City of North Las Vegas • All roads are swept twice monthly 

Clark County, 

Nevada 

State of Nevada • All freeways in Clark County are swept once a 

week 

• All arterials under state jurisdiction in Clark County 

are swept once a month 

Maricopa Association of 

Governments 

• Commitment to allocate $3.8 million CMAQ funds 

for PM-efficient sweepers 

• Funding dispersed competitively based on 

commitment to utilize equipment. Program 

designed to encourage additional sweeping efforts 

by local agencies 

City of Avondale • Conducts routine sweeping of residential streets 

Town of Carefree • Program for sweeping streets as necessary 

Town of Cave Creek • Sweeps streets twice a year utilizing rented 

sweepers 

• Also utilizes two water trucks to flush paved roads 

as needed 

City of Chandler • Has increased street sweeping on residential 

streets to once every 30 days and arterial streets 

to once every 14 days 

• Downtown streets are swept once a week 

City of El Mirage • Sweeps streets four times a year using 

contractors 

Town of Fountain Hills • Sweeps streets on a frequent basis 

Town of Gilbert • Downtown area streets are swept once a week 

• Residential streets are swept once a month 

Maricopa Co., 

Arizona 

 

City of Glendale • Regularly sweeps streets using mechanical broom 

sweepers 
6-52 

Table 6-20 

Summary of Street Sweeping Frequency for 

Paved Roads 

(continued) 

Area Agency Sweeping Program 

City of Goodyear • Sweeps streets on a daily basis using a 

mechanical broom sweeper 

City of Mesa • Conducts periodic sweeping of residential and 

major arterial streets 

City of Paradise Valley • Initiating an enhanced street sweeping program. 

Program goal is to sweep every street once every 

six weeks. Currently, streets are swept once 

every 3 months 

City of Peoria • All streets are currently swept once a month. The 

City is working to increase the sweeping 

frequency to once every two weeks 

City of Phoenix • Conducts periodic sweeping of residential and 

major arterial streets. The City will continue to 

consider new PM-efficient street sweeping 

equipment 

Town of Queen Creek • Sweeps all curb and gutter streets four times per 

year 

City of Scottsdale • Sweeps all curbed miles of residential streets 

approximately once every three weeks 

• Commuter streets are swept once per week 

• Downtown streets are swept twice per week 

• City will continue to consider new PM-efficient 

street sweeping equipment 

City of Surprise • Sweeps streets once every ten working days 

• Heavily traveled arterials are swept more 

frequently as needed 

City of Tempe • Routinely sweeps all streets. Streets in the 

downtown are flushed after special events 

City of Tolleson • Pursuant to Zoning Ordinance, Article IV, the City 

commits to strengthen its commitment to increase 

the frequency of street sweeping 

Town of Wickenburg • Routinely sweeps all paved streets 

Town of Youngtown • Ongoing monthly program of sweeping public 

streets 

Maricopa Co., 

Arizona 

(continued) 

 

 

Arizona Department of 

Transportation 

• Provides for street sweeping on state highways 

through intergovernmental agreements and 

contractors. These efforts are supplemented by ad 

hoc sweeping performed by state personnel using 

state-owned equipment 
6-53 

Based on the information contained in the Maricopa 

County SIP, the sweeping programs implemented in 

Clark County provide for more frequent street sweeping 

overall than programs implemented in Maricopa County. 

When the ratio of PM-efficient street sweeping 

equipment is factored into this analysis, the Clark 

County programs provide for much greater emissions 

reductions than equivalent programs in Maricopa 

County. 

6.3.4.5 Control Measures for Cleanup of Deposition 

from Natural Events and Spills

Requirements and programs for the cleanup of 

deposited materials from natural events and spills onto 

paved roads are summarized in Table 6-21. 

Clark County Program 

More Stringent 

Table 6- 21 

Summary of Requirements and Programs for Cleanup of 

Natural Events and Spills onto Paved Roads 

Area Rule # Requirements 

Clark County Public 

Works 

• On average, cleanup of deposition from natural events 

and spills initiated within 15 to 30 minutes of the call for 

assistance during work hours and one hour or less 

after hours. Natural events such as major floods 

require additional time to mobilize. The magnitude of 

events varies widely, precluding characterization in 

terms of average cleanup time. Truck spills may 

require as little as one hour or as much as six hours for 

cleanup 

City of Henderson • When natural events result in high silt loadings, loaders 

and dump trucks are employed to remove the heaviest 

debris, followed by broom sweepers, followed by 

regenerative air sweepers. Truck spills are responded 

to within four hours and cleanup continues until the 

work is completed. 

Clark County, 

Nevada 

 

 

 

 

City of Las Vegas • The City of Las Vegas responds immediately to any 

large-scale storm event. Cleaning continues around 

the clock until all storm-related debris and sediment are 

removed 
6-54 

Table 6- 21 

Summary of Requirements and Programs for Cleanup of 

Natural Events and Spills onto Paved Roads 

(continued) 

Area Rule # Requirements 

City of North Las 

Vegas 

• The Roadway Maintenance Division begins response 

to storm events with sweepers and other necessary 

equipment immediately. All paved roadways impacted 

by storm events are swept within 48 hours following the 

event. Truck spills are responded to immediately 

during work hours and within one hour after hours 

Clark County, 

Nevada 

(continued) 

State of Nevada, 

Department of 

Transportation 

• Where exceptional events and spills occur, the District 

immediately applies all necessary manpower and 

equipment to mitigate the situation 

Maricopa Co., 

Arizona 

Rule 310.01 

§ 306 • Cleanup of deposited material within 24 hours of 

discovery or prior to resumption of traffic on pavement 

where the pavement area has been closed to traffic 

SCAQMD, 

California 

Rule 1186(d)(1) • Public agencies must begin removal of visible roadway 

accumulations on public paved roads within 72 hours 

of notification

Maricopa County has adopted requirements for rapid 

cleanup of erosion-caused deposition of bulk materials 

onto paved surfaces. Under these requirements, 

material cleanup must begin within 24 hours of 

identification or prior to reopening of a road to traffic 

where the road has been closed. These cleanup 

requirements are not limited to public roads; they apply 

to all paved surfaces. The SCAQMD has implemented 

rapid cleanup requirements under Rule 1186. The 

South Coast requirements entail initiating cleanup within 

72 hours of discovery and apply only to public paved 

roads. 

In Clark County, all Public Works agencies have action 

plans or policies in place to facilitate the rapid cleanup 

of materials deposited on paved roads by storms and 

spills as summarized in Table 6-21. However major 

storm events do occur that cause extensive damage 

and deposition of material on roadways. It is not 

technologically feasible for cleanup of major storm 

events to be completed within 24 hours in all situations 

due to the extent of damage experienced. 

Clark County Has 

Implemented an 

Extensive Set of 

Requirements for 

Construction Activities
6-55 

Clark County has also developed an extensive flood 

control system to minimize the impact of natural events. 

As noted in Chapter 2, precipitation is limited in the Las 

Vegas Valley and averages only 4.13 inches per year. 

However, annual rainfall can vary substantially from 

year to year and from rainfall event to rainfall event. In 

general, rainfall events are infrequent but may result in 

intense precipitation. As a result, the infrastructure for 

handling storm water is necessarily robust to the extent 

that minor storms do not generally result in significant 

off-site deposition of material. The flood control program 

for the area is directed by the Clark County Regional 

Flood Control District. The District was created in 1986 

and was charged with the responsibility of developing 

and implementing a comprehensive flood control master 

plan to alleviate flooding in Clark County. Funding has 

been provided through voter-approved sales taxes and 

General Obligation Flood Control Bonds. Since 1987 

the District has funded projects totaling over $600 

million. Completed facilities include 45 detention basins 

and approximately 220 miles of channels, washes, and 

storm drains. Additionally, there are approximately $1.1 

billion in flood control facilities identified in the Master 

Plan for future funding. 

The natural event action plans or policies in place in 

Clark County and the cities of North Las Vegas, Las 

Vegas, and Henderson to deal with cleanup when a 

major storm event does occur complement the work of 

the Flood Control District. The plans entail mobilization 

of all available equipment from unaffected areas to the 

event location(s) and removal of heavy silt deposits as 

quickly as possible. Since completion of the flood 

control system to handle a 100-year storm is years out 

(pending an additional $1.1 billion in funding), there is 

still the possibility of widespread erosion and deposition 

from a major storm. The entities’ plans require quick 

response and focus maximum resources on the cleanup 

of roadways. However, time periods for initiating and 

completing cleanup of all silt deposits are not 

established since they may vary significantly from storm 

to storm. 

The existing Clark County cleanup programs have 

proven effective in practice. In July 2000, a 100-year 

flood event which caused significant flooding and 

Clark County 

Experiences Limited 

Impacts from Erosion 

Deposition 

Public Works 

Agencies Have 

Contingency Plans in 

Place for Flood Events 

Clark County 

Contingency Plans Are 

Effective 
6-56 

property damage occurred in the Las Vegas Valley. 

Public agencies expeditiously commenced cleanup of 

road debris in accordance with their response plans. 

During the two weeks following the event, while silt 

moisture was high, PM10 concentrations declined. All 

storm water deposits were cleaned up before they 

became sufficiently dry to cause elevated PM10

concentrations. Air quality standards were not 

exceeded and monitored concentrations were normal 

for that time period. Therefore, Clark County believes 

that its programs for cleanup of silt loading on paved 

roads are of equivalent stringency to those in other 

areas. 

6.3.5 Unpaved Roads 

The potential MSMs for paving or stabilizing unpaved 

roads are identified and analyzed in the following 

section. 

6.3.5.1 Control Measures for Paving Or Stabilizing 

Unpaved Roads 

Requirements for paving or stabilizing unpaved roads in 

Maricopa County and Clark County are summarized in 

Table 6-22. There were no other programs found for 

unpaved roads that were nearly as stringent as those 

implemented in these two areas.

Table 6- 22 

Summary of Requirements for Paving or Stabilizing Unpaved Roads 

Agency Rule # Requirements 

Clark County, 

Nevada 

AQR Section 91.2.1 

AQR Section 91.2.1.1 

SIP Commitment 

AQR Section 91.2.1.2 

• Pave or apply and maintain dust palliatives to stabilize all 

new unpaved roads constructed after June 22, 2000 

• Pave or apply and maintain dust palliatives to stabilize all 

existing unpaved roads with ADT ≥ 150 by June 1, 2003 

• Allocation of CMAQ funding to pave publicly owned and 

maintained unpaved roads over a three-year period 

ending June 1, 2003 

• Prohibition on construction of new unpaved roads or 

alleys in public thoroughfares after June 22, 2000 

City of Las Vegas • Commitment to pave all unpaved roads by the end of 

2006 
6-57 

Table 6- 22 

Summary of Requirements for Paving or Stabilizing Unpaved Roads 

(continued) 

Maricopa Co., 

Arizona 

Rule 310.01, 

Section 303 

SIP Commitment 

SIP Commitment 

SIP Commitment 

• Pave or apply and maintain dust palliatives to stabilize all 

existing unpaved roads with ADT ≥ 150 by June 10, 2004 

• SIP commitment of public agencies to accept dedication 

of certain privately owned unpaved roads 

• Public agencies develop and implement programs to 

stabilize unpaved roads 

• Design standard restrictions on new unpaved roads 

Both Maricopa and Clark County have developed 

comprehensive programs for stabilizing unpaved roads 

utilizing a combination of regulations and SIP 

commitments by the various jurisdictions to implement 

control measures. There are a few distinctions between 

the two programs. Clark County Regulation 91 requires 

stabilization of all new unpaved roads constructed after 

June 2000, and prohibits construction of new unpaved 

roads or alleys in public thoroughfares after June 2000. 

Maricopa Rule 310.01 does not have the new unpaved 

roads prohibition, but the requirement to stabilize 

unpaved roads with ADT greater than 150 by June 2004 

would apply. Also, Maricopa depends on the 

jurisdictions to establish unpaved road restrictions 

through design standards or other locally adopted 

stabilization requirements which are identified in 

their SIP commitments. Most jurisdictions have 

established requirements that limit or prevent the 

building of new unpaved roads, particularly roads 

serving new subdivisions and commercial and 

residential developments. Clark County Rule 91 

requirements for new unpaved roads are more 

comprehensive as they specifically prohibit new 

unpaved roads and apply uniformly to all jurisdictions in 

the nonattainment area. 

Maricopa Rule 310.01 requires stabilization of existing 

unpaved roads with an ADT greater than 150 by June 

2004. AQR Section 91 has the same stabilization 

requirement but with an earlier completion date of June 

2003, and there is a SIP commitment to allocate 

Congestion Mitigation and Air Quality Improvement 

Program (CMAQ) funds to all jurisdictions as needed to 
6-58 

pave publicly owned and maintained roads by that date. 

The Maricopa jurisdictions made a variety of SIP 

commitments ranging from the City of Phoenix 

commitment to pave all unpaved roads regardless of 

ADT, to others like Maricopa County that committed to 

meet the 2004 deadline to pave public roads with ADT 

greater than 150. The City of Las Vegas has made a 

commitment to pave all unpaved public roads 

regardless of ADT. Clark County also has an 

established Emissions Reduction Credit (ERC) program 

that, although not a SIP commitment, provides credits 

for paving roads below 150 ADT. Although it is not 

possible to quantify the overall impact of these various 

SIP commitments, the conclusion is that the Clark 

County unpaved roads requirement is at least as 

stringent as Maricopa’s due to the earlier completion 

date established for paving roads over 150 ADT, the 

commitment to pave roads versus using other less 

efficient stabilization methods, and having programs 

identified that will result in paving roads with less than 

150 ADT. 

Overall, the combined effects of AQR Section 91 and 

the SIP commitments result in a program to reduce 

emissions from unpaved roads in Clark County that is at 

least as stringent as the program established in 

Maricopa County, and more stringent than any program 

implemented in other states. 

6.4 MOST STRINGENT MEASURE SUMMARY 

This Chapter provided documentation to satisfy the 

most stringent measure (MSM) requirement established 

by the CAAA, Section 188(e) as one of the requirements 

necessary to support a request for extension of the 

Serious Area PM10 attainment date beyond the 

established December 31, 2001 deadline. 

Clark County followed U. S. EPA’s proposed policy for 

demonstrating the inclusion of the most stringent 

measures in the SIP as provided in Federal Register 

Notice 65 FR 19968, dated April 13, 2000. A five-step 

process for determining MSM, similar to that used for 

BACM determinations, was utilized. A complete 

analysis comparing the potentially most stringent 

Clark County 

Requirements Are 

More Stringent than 

Other States’ 

BACM/MSM 
6-59 

measures that are included in the implementation plan 

of any state, or are achieved in practice in any state 

against the control measures implemented in the Las 

Vegas area was accomplished and fully documented. 

Through this analysis and comparison, it has been 

demonstrated that the maximum degree of emission 

reduction that has been required or achieved from a 

source or source category in other SIPs or in practice in 

other states, and that can be feasibly implemented in 

the Las Vegas area, has been achieved by the 

implemented control measures. 

The next chapter addresses the formal request for 

extension of the 24-hour PM10 NAAQS attainment date 

to December 31, 2006. 

Clark County Followed 

U. S. EPA’s Proposed 

Policy in Evaluating 

MSM 
7-1 

CHAPTER 7 - REQUEST FOR EXTENSION OF THE 

ATTAINMENT DATE FOR PM10

7.1 INTRODUCTION 

Clark County is requesting an extension of the 

attainment date for the 24-hour PM10 National 

Ambient Air Quality Standard (NAAQS). Section 

188(e) of the 1990 Clean Air Act Amendments 

(CAAA) allows the U.S. EPA to extend the “Serious 

Area” attainment date up to five years upon 

application by the State if certain requirements are 

satisfied. The purpose of this chapter, in addition to 

formalizing the request for the extension, is to 

present supporting documentation that the 

extension request is warranted and CAAA 

requirements for granting an extension are met. 

The PM10 health standards are set at 150 

micrograms per cubic meter (μg/m3) for a 24-hour 

period average, and 50 μg/m3 for an annual 

average. The expected timeline for attaining these 

health standards are different. In the case of the 

annual average health standard, attainment can be 

demonstrated by the CAAA-required date of 

December 31, 2001. The 24-hour health standard 

is more problematic and attainment is not expected 

until 2006. A full five-year extension of the 

attainment date from 2001 to 2006 is requested for 

the 24-hour health standard. 

7.2 REQUIREMENTS FOR AN EXTENSION 

Section 188(e) of the 1990 CAAA allows the U.S. 

EPA to extend the attainment date for a serious 

area for up to five years beyond 2001 if attainment 

by 2001 is impracticable. In addition to a formal 

request to the U.S. EPA for an extension, the 

requirements for an extension include the following: 

1. Compliance with requirements and 

commitments applicable to the Las Vegas 

Valley in the State Implementation Plan (SIP); 

Formal Request for 

Extension of 

Attainment Deadline 

Extension of 

Attainment Date Not 

Necessary for 

Annual Standard 

Extension of 

Attainment Date to 

2006 Requested for 

24-Hour Standard 

Clean Air Act 

Criteria for Granting 

an Extension 
7-2 

2. A demonstration that attainment by 2001 is 

impracticable; 

3. Documentation that measures included in the 

SIP are as stringent as the Most Stringent 

Measures (MSM) that have been implemented 

by any state and/or achieved in practice in any 

state and are feasible for the area; and 

4. A demonstration that the expected attainment 

date is the most expeditious alternative date 

practicable. 

7.3 COMPLIANCE WITH ALL REQUIREMENTS 

AND COMMITMENTS 

This State Implementation Plan (SIP) for the Las 

Vegas Valley complies with all requirements in 

sections 172 and 189 of the 1990 CAAA relating to 

“serious” PM10 nonattainment areas. Chapter 4 

documents adoption and implementation of control 

measures designed to attain PM10 National Ambient 

Air Quality Standards (NAAQS) at the earliest 

practicable date. These control measures 

constitute Reasonably Available Control Measures 

(RACM) and Best Available Control Measures 

(BACM) for all significant sources of PM10. Chapter 

4 and corresponding appendices also present 

documentation on the public hearing process, 

implemented control measures, and SIP 

commitments. 

Chapter 3 and Chapter 5, along with corresponding 

appendices, present emissions inventories, 

emissions projections, and attainment 

demonstration modeling in accordance with U.S. 

EPA regulations, guideline documents, and 

policies. A demonstration that attainment of the 24-

hour standard by 2001 is impracticable is presented 

in the next section. 

The SIP Complies 

with All 

Requirements for an 

Extension 
7-3 

7.4 ATTAINMENT OF PM10 NAAQS BY 2001 IS 

IMPRACTICABLE 

Subsequent sections present both quantitative and 

qualitative documentation that attainment of the 24-

hour PM10 NAAQS by 2001 is impracticable. PM10 

emission estimates and projections of emissions 

and concentrations for 2001 are derived from the 

proportional rollback approach, which was 

discussed at length in Chapters 3, 4, and 5. The 

implementation schedule for control measures and 

expected 24-hour concentrations in 2001 are 

discussed below.

Since PM10 in the Las Vegas Valley is dominated 

by geologic materials from fugitive dust area 

sources, the focus of this SIP has been on the 

control of dust from the following significant area 

sources: disturbed open areas, construction 

activities, paved roads, and unpaved roads. 

Controls on these sources are implemented 

through the newly adopted Sections 90, 91, 92, 93, 

and 94 of the Clark County Health District’s Air 

Quality Regulations. These regulations are all in 

effect as of January 1, 2001. 

The emission reductions resulting from the 

regulations are sufficient to achieve attainment of 

the annual PM10 Standard by the CAAA-established 

deadline. However, additional time is necessary to 

achieve the reductions needed to attain the 24-hour 

standard as detailed below. 

As described in the SIP Commitments Section of 

Chapter 4, the Health District has committed to 

hiring 15 additional staff in order to implement and 

enforce the new regulations. A ten-member 

compliance team will be formed to focus on 

Sections 90, 91, 92, and 93, while five new staff 

members will be added to strengthen the existing 

construction activities programs and to implement 

Section 94 requirements. The process of funding, 

hiring, training, and utilizing the additional staff has 

already begun, and will be completed during 

calendar year 2001. 

Fugitive Dust 

Sources Dominated 

the PM10 Emission 

Inventory

 

New Enforcement 

Staff Will be Hired 

and Trained in 2001 
7-4 

The control measure effectiveness values utilized in 

this SIP are predicated on this schedule. The 

Overall Control Measure Reductions column in 

Table 4-14 reflects the significant increase in 

control measure effectiveness from 2001 to 2002 

that will be realized from the work activities of the 

additional staff. Earlier realization of these 

reductions is not practicable due to the time 

required to hire and train new staff to the 

proficiency level needed to effectively implement 

the additional dust control programs. 

The control measure for unpaved road dust as 

described in Chapter 4 prohibits the construction of 

new unpaved roads, and a SIP commitment has 

been made to establish a schedule to pave all 

existing publicly owned unpaved roads with an ADT 

of 150 or greater by June 30, 2003. Clark County 

and the cities of Las Vegas, North Las Vegas, and 

Henderson have obligated over $25 million in 

Congestion Mitigation and Air Quality (CMAQ) 

funds (including local match) over the next three 

years for the paving program. The funding 

commitment will support completing approximately 

one-third of the total paving requirement each year 

from 2001 through 2003. The overall control 

reduction percentage from this control measure will 

increase from 22 percent in 2001 to 65 percent in 

2003. The maximum benefit that will be realized at 

the end of 2003 cannot practicably be achieved 

earlier due to funding limitations in each year. 

Chapter 5, utilizing the implementation schedule for 

controls and expected emission reductions that will 

be achieved, provides quantitative documentation 

that PM10 emissions and corresponding 

concentrations are not sufficiently reduced to allow 

for attainment of the 24-hour PM10 health standard 

by 2001. More specifically, valley-wide proportional 

rollback modeling for 2001 and the resulting 

inventory presented in Appendix L, Table L-21, 

Valley-wide 2001 24-Hour Inventory, demonstrate 

that the projected 24-hour PM10 concentrations in 

2001 will be 209 micrograms per cubic meter after 

controls are applied. Although this represents a 

significant reduction from the projected design 

Unpaved Roads with 

Greater Than 150 

ADT Will be Paved 

by the End of 2003

 

The 24-Hour NAAQS 

Cannot be Attained 

in 2001 
7-5 

day concentration of 281 μg/m3, it is still far short of 

the 150 μg/m3 standard. The 150 μg/m3 24–hour 

standard cannot practicably be achieved by the end 

of 2001. 

7.5 DOCUMENTATION ON INCLUSION OF MOST 

STRINGENT MEASURES (MSM) 

Chapter 6 provides the MSM analysis in 

accordance with U.S. EPA’s proposed policy for 

satisfying the Section 188(e) requirements. 

Documentation was presented showing that the 

PM10 controls contained in this State 

Implementation Plan for the Las Vegas Valley are 

as stringent as those included in implementation 

plans of any state, or achieved in practice in any 

state, that can feasibly be implemented in the Las 

Vegas Valley. 

Chapter 4 documented the control measure 

development and implementation process that 

resulted in the best available control measures 

(BACM) being applied to control significant PM10

sources. The process for identifying MSMs was 

similar to BACM except for one additional step that 

compared potential MSMs with those measures 

adopted for the Las Vegas Valley. 

The MSM analysis in Chapter 6 demonstrated that 

the maximum degree of emission reduction that has 

been required or achieved from a source or source 

category in other SIPs or in practice in other states, 

and that can be feasibly implemented in the Las 

Vegas area, has been achieved by the 

implemented control measures. 

7.6 DEMONSTRATION THAT 2006 IS THE MOST 

EXPEDITIOUS ALTERNATIVE DATE 

PRACTICABLE FOR ATTAINMENT OF THE 24-

HOUR PM10 NAAQS

In order to determine if 2006 is the most 

expeditious alternative date for attainment of the 

RACM/BACM 

Adopted in Clark 

County are the Most 

Stringent Control 

Measures

 
7-6 

24-hour NAAQS, Chapter 5 presented a 

Reasonable Further Progress (RFP) Analysis for 

2003. The following sections discuss the results of 

the RFP analysis and present the expected 24-hour 

concentrations in the proposed attainment year of 

2006. 

 

7.6.1 Expected 24-Hour Concentrations in 2003 

In Section 7.4, information was provided to 

document the impracticability of attaining the 

24-hour standard by 2001. It was noted that control 

measure effectiveness would improve significantly 

after 2001 when the commitment to increase 

staffing at the Health District’s Air Quality Division is 

completed. Unpaved road emissions would be 

reduced through the program to pave roads over a 

three-year period from 2001 to 2003, with the 

maximum reduction rate achieved by the end of 

2003. An analysis of the progress towards 

attainment was conducted for the end of 2003 to 

quantify the emission reductions achieved. The 

results of the Reasonable Further Progress 

Analysis are depicted in Figure 5-2 which shows 

projected tons of emissions for 2003 and 2006 after 

quantifying emission reductions which result from 

the implementation of the committed control 

measures. 

The projected 2003 emissions level of 277 tons 

represents a reduction of more than 70 percent

from the base year 1998 emissions. Additional 

reductions of approximately 25 percent are required 

to reach the attainment level of 206 tons per day. 

The greater-than-50 percent reduction of emissions 

toward the attainment level by 2003 does 

demonstrate reasonable further progress, and also 

illustrates the impracticability of achieving 

attainment earlier than 2006. 

Appendix M further documents the progress toward 

attainment with a detailed breakdown of the 

inventory projections for 2003. The overall control 

measure reductions applied to the 2003 inventory 

are the same as applied to the 2006 emission 

inventory except for unimproved shoulders 

Reasonable Further 

Progress was 

Demonstrated for 

2003
7-7 

on paved roads, which will not be fully implemented 

by 2003. These control measure reductions are 

described in detail in Appendix L. SIP 

commitments for paving unpaved shoulders are 

described in Section 4.8. Participating state and 

local entities are committed to prepare a plan that 

will identify and prioritize paving requirements for 

unpaved shoulders as well as unpaved roads with 

an ADT of less than 150. Beyond fiscal year 2003, 

and after completion of the program to pave 

unpaved roads with an ADT of greater than 150, 

CMAQ funds will be allocated as necessary to 

complete each entity’s plan for stabilizing shoulders 

and paving unpaved roads by December 31, 2006. 

 

Chapter 4 addresses the process that will be 

followed by public works agencies to develop a 

detailed plan for the stabilization of unimproved 

shoulders on paved roads. This program will be 

accomplished with CMAQ funds after the 

commitment to pave unpaved roads is completed in 

2003, with the paving of the unstable shoulders to 

be completed by the end of 2006. 

 

7.6.2 Expected 24-Hour Concentrations in 2006 

and the Attainment Demonstration 

The expected 24-hour concentrations on a valleywide and micro-area basis are presented in 

Chapter 5 for the 2006 attainment year. The 

proportional rollback modeling indicates that 24-

hour concentrations on a valley-wide and microarea basis are below the 24-hour PM10 NAAQS 

(150 micrograms per cubic meter). Combined with 

the need for three years of air quality monitoring 

data to account for year-to-year variability in 

meteorological conditions, the attainment 

demonstration in Chapter 5 is clear documentation 

that 2006 is the most expeditious alternative date 

for attainment of the 24-hour PM10 standard. 

7.7 SUMMARY 

 

This chapter is a formal request for an extension of 

the attainment date for the 24-hour PM10 NAAQS. 

A five-year extension of the attainment date from 

2006 is the Most 

Expedient Date to 

Attain the 24-Hour 

Standard 

 
7-8 

2001 to 2006 is requested for the 24-hour PM10

NAAQS. Section 188(e) of the 1990 Clean Air Act 

Amendments (CAAA) allows the U.S. EPA to 

extend the “Serious Area” attainment date up to five 

years from 2001 upon application by the state if 

certain requirements are satisfied. Documentation 

of the following requirements were provided: 

1. A demonstration that attainment by 2001 is 

impracticable; 

2. Compliance with requirements and 

 commitments applicable to the Las Vegas 

 Valley in the SIP; 

3. Documentation that the control measures 

 included in the SIP are as stringent as the 

 most stringent measures in the 

 implementation plan of any state and/or 

 achieved in practice in any state that are 

 feasible for the area; and 

4. A demonstration that the 2006 attainment 

 date is the most expeditious alternative date 

 practicable. 

All of the issues discussed in this Chapter 

underscore the need and reasonableness of a fiveyear extension of the attainment date for the 24-

hour PM10 NAAQS. 

Formal Request for 

a Five-Year 

Extension of the 

Attainment Date for 

the 24-Hour PM10 

NAAQS