The EPA Region 9 Acting Regional Administrator Alexis Strauss signed the following proposed rule on June 27, 2014 and EPA is 

submitting it for publication in the Federal Register (FR). While we have taken steps to ensure the accuracy of this Internet 

version of the rule, it is not the official version of the rule for purposes of public comment. Please refer to the official version in 

a forthcoming FR publication, which will appear on the Government Printing Office’s FDsys website 

(http://fdsys.gpo.gov/fdsys/search/home.action) and on Regulations.gov (http://www.regulations.gov) in Docket No. EPA-R09-

OAR-2013-0735. 

Billing Code: 6560-50-P 

ENVIRONMENTAL PROTECTION AGENCY 

40 CFR Parts 52 and 81 

[EPA-R09-OAR-2013-0735; FRL-] 

Approval of Implementation Plans and Designation of Areas for 

Air Quality Planning Purposes; Las Vegas Valley, Nevada; 

Redesignation to Attainment for PM10 

AGENCY: Environmental Protection Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: The Environmental Protection Agency (EPA) is proposing 

to approve a revision to the Nevada state implementation plan 

that provides for the maintenance of the national ambient air 

quality standard for particulate matter with an aerodynamic 

diameter less than or equal to a nominal ten micrometers (PM10) 

in Las Vegas Valley for the next ten years and to approve the 

related motor vehicle emissions budgets. Based in part on the 

proposed approval of the PM10 maintenance plan, EPA is also 

proposing to approve the State of Nevada’s request for 

redesignation of Las Vegas Valley to attainment for the PM10

standard. Consistent with the assumptions of the maintenance 

plan, EPA is proposing to approve revisions to certain local 

fugitive dust rules to ensure their continued applicability 

after redesignation of the area to attainment. Lastly, EPA is 
This document is a prepublication version, signed by EPA Region 9 Acting Regional Administrator Alexis Strauss on June 27, 

2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

2 

proposing to delete the area designation for Las Vegas Valley 

for the revoked national standard for total suspended 

particulate because the designation is no longer necessary. 

DATES: Comments must be received on or before [Federal Register: 

Insert date 30 days after the publication date]. 

ADDRESSES: Submit your comments, identified by Docket ID Number 

EPA-R09-OAR-2013-0735, by one of the following methods: 

1. http://www.regulations.gov: Follow the on-line 

instructions for submitting comments. 

2. Email: oconnor.karina@epa.gov. 

3. Mail or deliver: Karina OConnor (AIR-2), U.S. 

Environmental Protection Agency, Region IX, 75 Hawthorne Street, 

San Francisco, CA 94105-3901. Deliveries are only accepted 

during the Regional Office's normal hours of operation. 

Instructions: All comments will be included in the public 

docket without change and may be made available online at 

http://www.regulations.gov, including any personal information 

provided, unless the comment includes Confidential Business 

Information (CBI) or other information whose disclosure is 

restricted by statute. Information that you consider CBI or 

otherwise protected should be clearly identified as such and 

should not be submitted through http://www.regulations.gov or 

email. http://www.regulations.gov is an anonymous access system, 

and EPA will not know your identity or contact information 
This document is a prepublication version, signed by EPA Region 9 Acting Regional Administrator Alexis Strauss on June 27, 

2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

3 

unless you provide it in the body of your comment. If you send 

email directly to EPA, your email address will be automatically 

captured and included as part of the public comment. If EPA 

cannot read your comment due to technical difficulties and 

cannot contact you for clarification, EPA may not be able to 

consider your comment. 

Docket: Documents in the docket for this action are 

generally available electronically at www.regulations.gov and in 

hard copy at EPA Region IX, 75 Hawthorne Street, San Francisco, 

California. While all documents in the docket are listed at 

www.regulations.gov, some information may be publicly available 

only at the hard copy location (e.g., copyrighted material, 

large maps), and some may not be publicly available in either 

location (e.g., CBI). To inspect the hard copy materials, please 

schedule an appointment during normal business hours with the 

contact listed in the FOR FURTHER INFORMATION CONTACT section. 

FOR FURTHER INFORMATION CONTACT: Karina O’Connor, Air Planning 

Office (AIR-2), U.S. Environmental Protection Agency, Region IX, 

(775) 434-8176, oconnor.karina@epa.gov. 

SUPPLEMENTARY INFORMATION: Throughout this document, whenever 

“we,” “us,” or “our” is used, we mean the EPA. This 

supplementary information section is arranged as follows: 

Table of Contents 

I. Summary of Today’s Proposed Action 
This document is a prepublication version, signed by EPA Region 9 Acting Regional Administrator Alexis Strauss on June 27, 

2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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II. Background 

III. Procedural Requirements for Adoption and Submittal of SIP 

Revisions 

IV. Substantive Requirements for Redesignation 

V. Evaluation of the State’s Redesignation Request for the Las 

Vegas Valley PM10 Nonattainment Area 

A. Determination That the Area Has Attained the PM10 NAAQS. 

B. The Area Must Have a Fully-Approved SIP Meeting 

Requirements Applicable for Purposes of Redesignation under 

Section 110 and Part D. 

1. Basic SIP Requirements under CAA Section 110 

2. SIP Requirements under Part D 

3. Conclusion With Respect To Sections 107(d)(3)(E)(ii) and 

(v) 

C. The Area Must Show the Improvement in Air Quality is Due to 

Permanent and Enforceable Emissions Reductions. 

D. The Area Must Have a Fully-Approved Maintenance Plan under 

CAA Section 175A. 

1. Attainment Inventory 

2. Maintenance Demonstration 

3. Monitoring Network 

4. Verification of Continued Attainment 

5. Contingency Provisions 

6. Subsequent Maintenance Plan Revisions 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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7. Motor Vehicle Emissions Budgets 

VI. Evaluation of Revisions to Clark County Fugitive Dust Rules 

VII. Proposed Deletion of TSP Designation for Las Vegas Valley 

VIII. Proposed Action and Request for Public Comment 

IX. Statutory and Executive Order Reviews 

I. Summary of Today's Proposed Action 

Under Clean Air Act (CAA or “Act”) section 110(k)(3), EPA 

is proposing to approve a submittal from the Nevada Division of 

Environmental Protection (NDEP) dated September 7, 2012 of the 

Redesignation Request and Maintenance Plan for Particulate 

Matter (PM10), Clark County, Nevada (August 2012) (“Las Vegas 

Valley PM10 Maintenance Plan”) as a revision to the Nevada state 

implementation plan (SIP). 

EPA finds that the Las Vegas Valley PM10 Maintenance Plan 

adequately demonstrates that the area will maintain the PM10

national ambient air quality standard (NAAQS or “standard”) for 

10 years beyond redesignation and includes sufficient 

contingency provisions to promptly correct any violation of the 

PM10 standard which occurs after redesignation and thereby meets 

the requirements for maintenance plans under CAA section 175A. 

EPA is also proposing to approve the motor vehicle emissions 

budgets (MVEBs) in the Las Vegas Valley PM10 Maintenance Plan 

because we find they meet the applicable transportation 

conformity requirements under 40 CFR 93.118(e). 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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Under CAA section 107(d)(3)(D), EPA is also proposing to 

approve NDEP’s request to redesignate the Las Vegas Valley PM10

nonattainment area from “nonattainment” to “attainment” for the 

PM10 standard. We are doing so based on our conclusion that the 

Las Vegas Valley has attained the PM10 standard; that the 

relevant portions of the Nevada SIP are fully approved; that the 

improvement in air quality is due to permanent and enforceable 

emissions reductions; that the State of Nevada has met all of 

the requirements applicable to the Las Vegas Valley PM10

nonattainment area with respect to section 110 and part D of the 

CAA; and, based on our proposed approval as described above, 

that the Las Vegas Valley PM10 Maintenance Plan meets the 

requirements for maintenance plans under section 175A of the 

CAA; and that, therefore, the State of Nevada has met the 

criteria for redesignation under CAA section 107(d)(3)(E) for 

the Las Vegas Valley PM10 nonattainment area. 

Third, we are proposing to approve certain fugitive dust 

rules that Clark County has amended to ensure their continued 

applicability after the area is redesignated to attainment. NDEP 

submitted the amended rules on May 27, 2014 as a revision to the 

Nevada SIP. 

Lastly, EPA is proposing to delete the area designation for 

Las Vegas Valley for the revoked NAAQS for total suspended 

particulate. 
This document is a prepublication version, signed by EPA Region 9 Acting Regional Administrator Alexis Strauss on June 27, 

2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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II. Background

On April 30, 1971 (36 FR 8186), pursuant to section 109 of 

the CAA, as amended in 1970, EPA promulgated the original NAAQS 

for the “criteria” pollutants, which included carbon monoxide, 

hydrocarbons, nitrogen dioxide, photochemical oxidant, sulfur 

dioxide, and particulate matter. The NAAQS are set at 

concentrations intended to protect public health and welfare. 

The original NAAQS for particulate matter was defined in terms 

of a reference method that called for measuring particulate 

matter up to a nominal size of 25 to 45 micrometers or microns. 

This fraction of total ambient particulate matter is referred to 

as “total suspended particulate” or TSP. Within nine months 

thereafter, each State was required under section 110 of the 

1970 amended Act to adopt and submit to EPA a plan, referred to 

as a State Implementation Plan (SIP), which provides for the 

implementation, maintenance, and enforcement of each of the 

NAAQS within each State. The State of Nevada submitted its SIP 

on January 28, 1972, and EPA approved it later that year. See 37 

FR 10842 (May 31, 1972). 

Generally, SIPs were to provide for attainment of the NAAQS 

within three years after EPA approval of the plan. However, many 

areas of the country did not attain the NAAQS within the 

statutory period. In response, Congress amended the Act in 1977 

to establish a new approach, based on area designations, for 
This document is a prepublication version, signed by EPA Region 9 Acting Regional Administrator Alexis Strauss on June 27, 

2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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attaining the NAAQS. Under section 107(d) of the 1977 amended 

Act, States were to make recommendations for all areas within 

their borders as attainment, nonattainment, or unclassifiable 

for each of the NAAQS, including TSP, and EPA was to designate 

areas based on those recommendations, as modified if 

appropriate. For the State of Nevada, the State recommended, and 

EPA approved, the use of hydrographic areas as the geographic 

basis for designating air quality planning areas. See 67 FR 

12474 (March 19, 2002). For the TSP NAAQS, EPA designated a 

number of areas in Nevada as “nonattainment,” including Las 

Vegas Valley1 (hydrographic area (HA) #212). See 43 FR 8962, at 

9012 (March 3, 1978). The area designations for air quality 

planning purposes within the State of Nevada are codified at 40 

CFR 81.329. 

As amended in 1977, the CAA required States to revise their 

SIPs by January 1979 for all designated nonattainment areas. The 

various local entities and the State of Nevada responded by 

developing and submitting attainment plans for the TSP 

 

1 The Las Vegas Valley encompasses roughly 1,500 square miles within Clark 

County and includes the cities of Las Vegas, North Las Vegas, and Henderson. 

Roughly two million people reside in Clark County, mostly within Las Vegas 

Valley. NDEP is the state agency under state law that is responsible for SIP 

matters for the State of Nevada. Within Clark County, the Clark County Board 

of County Commissioners, acting through the Clark County Department of Air 

Quality (Clark County DAQ), is empowered under state law to develop air 

quality plans and to regulate stationary sources within the county with the 

exception of certain types of power plants, which lie exclusively within the 

jurisdiction of NDEP. 
This document is a prepublication version, signed by EPA Region 9 Acting Regional Administrator Alexis Strauss on June 27, 

2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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nonattainment areas, including Las Vegas Valley, and in 1981, 

EPA approved these plans on condition that the State submit, 

within a prescribed period of time, revisions to correct certain 

deficiencies. See 46 FR 21758 (April 14, 1981). In 1982, we 

found that the State had submitted the required revisions 

correcting the identified deficiencies, and we revoked the 

conditions placed on our approval of the TSP plans. See 47 FR 

15790 (April 13, 1982). 

In 1987, EPA revised the NAAQS for particulate matter, 

eliminating TSP as the indicator for the NAAQS and replacing it 

with the “PM10” indicator. See 52 FR 24634 (July 1, 1987). PM10 

refers to particles with an aerodynamic diameter less than or 

equal to a nominal 10 microns. At that time, EPA established two 

PM10 standards: a 24-hour standard of 150 micrograms per cubic 

meter (μg/m3) and an annual standard of 50 μg/m3.2 We indicated 

in the preamble to our regulations implementing the then-new PM10

NAAQS that we would consider deletion of TSP area designations 

once EPA had reviewed and approved revised SIPs that include 

control strategies for the PM10 NAAQS and once EPA had 

promulgated PM10 increments for the prevention of significant 

 

2 In 2006, EPA retained the 24-hour PM10 standard but revoked the annual PM10

standard. See 71 FR 61144 (October 17, 2006). More recently, as part of the 

Agency’s periodic review of the NAAQS, EPA reaffirmed the 24-hour PM10 NAAQS. 

See 78 FR 3086 (January 15, 2013). See 40 CFR 50.6 (“National primary and 

secondary ambient air quality standards for PM10”). 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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deterioration (PSD) program. See 52 FR 24672, at 24682 (July 1, 

1987). 

Under our regulations for implementing the revised 

particulate matter NAAQS (i.e., the PM10 NAAQS), EPA did not 

designate areas as nonattainment, attainment, or unclassifiable 

but categorized areas into three groups, referred to as Group I, 

Group II, or Group III. Group I areas were those that had a 

probability of not attaining the PM10 NAAQS (based on existing 

TSP data) of at least 90%. Group I areas were required to submit 

SIP revisions that contain full PM10 control strategies including 

a demonstration of attainment. See 52 FR 24672, at 24681 (July 

1, 1987). We identified the Las Vegas (HA #212) and Reno (HA 

#87, known as “Truckee Meadows”) planning areas as Group I 

areas. See 52 FR 29383 (August 7, 1987) and 55 FR 45799 (October 

31, 1990). 

The CAA was significantly amended in 1990. Under the 1990 

amended Act, Congress replaced the PM10 regulatory approach 

established by EPA in 1987 with the area designation concept and 

designated former “Group I” areas and certain other areas as 

nonattainment areas for PM10 by operation of law. See section 

107(d)(4)(B) of the Act. As former “Group I” areas, the Las 

Vegas planning area was designated as nonattainment areas for 

PM10 by operation of law. See 56 FR 11101 (March 15, 1991). 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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Las Vegas Valley was initially classified as a “moderate” 

PM10 nonattainment area but was later re-classified as a 

“serious” PM10 nonattainment area. See 58 FR 3334 (January 8, 

1993). States with “serious” PM10 nonattainment areas were 

required under the CAA, as amended in 1990, to submit revisions 

to their SIPs to, among other things, demonstrate attainment of 

the PM10 standard as expeditiously as practicable, but no later 

than 2001. See CAA section 188(c). However, EPA is authorized to 

extend the attainment date for such an area by up to 5 years if 

the State qualifies for an extension under the terms specified 

in the statute. See CAA section 188(e). To qualify, among other 

requirements, a State must demonstrate that the plan includes 

the most stringent measures (MSM) that are included in the SIP 

of any State or are achieved in practice in any State, and can 

feasibly be implemented in the area. 

In 2001, NDEP submitted the PM-10 State Implementation Plan 

for Clark County (June 2001) (“Las Vegas Valley PM10 Attainment 

Plan”) to EPA as a revision to the Nevada SIP to meet the 

requirements for “serious” PM10 nonattainment areas. In 2002, 

NDEP submitted certain amendments to the Las Vegas Valley PM10

Attainment Plan and a set of local fugitive dust rules relied 

upon by the plan. In 2004, EPA approved the Las Vegas Valley PM10

Attainment Plan, as amended, and the set of fugitive dust rules. 

See 69 FR 32273 (June 9, 2004). 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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Specifically, as part of our 2004 final action, EPA 

approved the following SIP elements: 

· The baseline and projected emissions inventories as 

required under CAA section 172(c)(3); 

· The demonstration that attainment of the 24-hour standard 

by December 31, 2001 is impracticable as required under CAA 

section 189(b)(1)(A); 

· The demonstration that attainment of the 24-hour standard 

will occur by the most expeditious alternative date 

practicable, in this case, December 31, 2006, as required 

under CAA sections 189(b)(1)(A) and 188(e); 

· The demonstration that the plan includes MSM as required 

under CAA section 188(e); 

· The demonstration that the plan provides for implementation 

of best available control measures (BACM) as required under 

CAA section 189(b)(1)(B); 

· The demonstration that major sources of PM10 precursors such 

as nitrogen oxides and sulfur dioxide do not significantly 

contribute to violations of the PM10 standards as authorized 

under CAA section 189(e); 

· The demonstration that the plan provides for reasonable 

further progress and quantitative milestones as required 

under CAA sections 189(c) and 172(c)(2); 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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· The contingency measures as required under CAA section 

172(c)(9); 

· Transportation conformity motor vehicle emissions budgets, 

including a budget of 141.41 tons per day beginning in year 

2006; and 

· Clark County fugitive dust rules: section 90 (“Fugitive 

Dust from Open Areas and Vacant Lots”), section 91 

(“Fugitive Dust from Unpaved Roads, Unpaved Alleys and 

Unpaved Easement Roads”), section 92 (“Fugitive Dust from 

Unpaved Parking Lots, Material Handling & Storage Yards, & 

Vehicle & Equipment Storage Yards”), section 93 (“Fugitive 

Dust from Paved Roads & Street Sweeping Equipment”), and 

section 94 (“Permitting & Dust Control for Construction 

Activities”). 

As noted above, EPA approved the demonstration in the Las 

Vegas Valley PM10 Attainment Plan of December 31, 2006 as the 

most expeditious practicable alternative attainment date, and in 

2010, based on a review of the ambient monitoring data for years 

2004-2006, EPA determined that the Las Vegas Valley PM10

nonattainment area had attained the 24-hour PM10 NAAQS by the 

approved alternative attainment date, i.e., December 31, 2006. 

See 75 FR 45485 (August 3, 2010).

On September 7, 2012, NDEP submitted the Las Vegas Valley 

PM10 Maintenance Plan and requested that EPA redesignate the Las 
This document is a prepublication version, signed by EPA Region 9 Acting Regional Administrator Alexis Strauss on June 27, 

2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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Vegas Valley PM10 nonattainment area to attainment for the 24-

hour PM10 NAAQS, and on May 27, 2014, NDEP submitted revised 

versions of Clark County’s fugitive dust rules that were amended 

by Clark County to ensure their continued applicability once the 

area is redesignated to attainment. In today’s proposed rule, we 

are proposing action on NDEP’s September 7, 2012 submittal of 

the Las Vegas Valley PM10 Maintenance Plan and request for 

redesignation to attainment, as well as the amended Clark County 

fugitive dust rules. 

The 1990 Act Amendments also provided for the continued 

transition from TSP to PM10. Specifically, section 107(d)(4)(B) 

states in relevant part: “Any designation for particulate matter 

(measured in terms of total suspended particulates) that the 

Administrator promulgated pursuant to this subsection (as in 

effect immediately before November 15, 1990) shall remain in 

effect for purposes of implementing the maximum allowable 

increases in concentrations of particulate matter (measured in 

terms of total suspended particulates) pursuant to section 

163(b) of this title, until the Administrator determines that 

such designation is no longer necessary for that purpose.” 

Section 166(f) of the 1990 amended Act authorizes EPA to 

replace the TSP increments with PM10 increments, and in 1993, EPA 

promulgated the PM10 increments and revised the PSD regulations 

accordingly. See 58 FR 31622 (June 3, 1993). In our June 1993 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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final rule, we indicated that the replacement of the TSP 

increments with PM10 increments negates the need for the TSP 

attainment or unclassifiable area designations to be retained. 

We also indicated that we would delete such TSP designations in 

40 CFR part 81 upon the occurrence of, among other 

circumstances, EPA’s approval of a State’s or local agency’s 

revised PSD program containing the PM10 increments. See 58 FR 

31622, at 31635 (June 3, 1993). 

In November 2002, we deleted the TSP attainment or 

unclassifiable area designations throughout the State of Nevada, 

except for those in Clark County. See 67 FR 68769 (November 13, 

2002). In April 2013, we deleted the TSP attainment or 

unclassifiable area designations within Clark County and deleted 

the TSP nonattainment area designations for all of the Nevada 

TSP nonattainment areas, except for the Las Vegas planning area 

(i.e., HA #212, Las Vegas Valley) and the Reno planning area 

(i.e., HA #87, Truckee Meadows).3 See 78 FR 22425 (April 16, 

 

3 In June 1992, the State of Nevada requested that we reclassify the eight 

existing TSP nonattainment areas in Nevada to “unclassifiable” status. See

letter from L.H. Dodgion, Administrator, NDEP, to Daniel W. McGovern, 

Regional Administrator, EPA Region IX, dated June 15, 1992. We believe that 

deletion of the TSP nonattainment designations is administratively more 

efficient than redesignation of the area to unclassifiable. As noted above, 

we have already deleted six of the TSP nonattainment area designations and 

are proposing to delete the one for Las Vegas Valley herein. We will consider 

deletion of the one other remaining TSP area designation, i.e., the TSP 

designation for Reno (HA #87, Truckee Meadows), in a future rulemaking. 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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2013). In today’s proposed rule, we are proposing to delete the 

TSP nonattainment area designation for Las Vegas Valley. 

III. Procedural Requirements for Adoption and Submittal of SIP 

Revisions 

Sections 110(a)(1) and 110(l) of the Act require States to 

provide reasonable notice and public hearing prior to adoption 

of SIP revisions. In this action, we are proposing action on 

NDEP’s September 7, 2012 submittal of the Las Vegas Valley PM10

Maintenance Plan (August 2012) as a revision to the Nevada SIP.4

We are also proposing action on NDEP’s May 27, 2014 submittal of 

Clark County’s amended fugitive dust rules as a revision to the 

Nevada SIP. These two submittals contain documentation of the 

public review process followed by Clark County and NDEP in 

adopting the SIP revisions prior to submittal to EPA. As 

discussed below, the documentation provides sufficient evidence 

that reasonable notice of public hearings was provided to the 

public and that public hearings were conducted prior to 

adoption. 

NDEP’s submittal of the Las Vegas Valley PM10 Maintenance 

Plan includes a letter dated August 27, 2012 from Lewis 

Wallenmeyer, Director, Clark County Department of Air Quality 

(Clark County DAQ), to Colleen Cripps, Administrator, NDEP, 

 

4 NDEP’s September 7, 2012 submittal of the Las Vegas Valley PM10 Maintenance 

Plan became complete by operation of law on March 7, 2013. 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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submitting the Las Vegas Valley PM10 Maintenance Plan and 

redesignation request to NDEP. NDEP’s letter dated September 7, 

2012 transmitting the plan to EPA and requesting that EPA 

approve the plan and redesignation request constitutes NDEP’s 

adoption of the plan as a revision to the Nevada SIP. 

Appendix B (“Documentation of the Public Review Process”) 

of the Las Vegas Valley PM10 Maintenance Plan includes a copy of 

the notice to the public published in a newspaper of general 

circulation on January 15, 2012 announcing a 30-day comment 

period on the proposed Las Vegas Valley PM10 Maintenance Plan and 

a public hearing after the close of the comment period; a copy 

of comments received and Clark County DAQ’s responses; various 

web notices issued by Clark County DAQ in connection with review 

of the proposed plan; and documentation of the public hearing on 

the proposed plan and subsequent adoption of the plan by the 

Clark County Board of County Commissioners on August 21, 2012. 

These materials adequately document the public review process 

followed by Clark County in adopting the plan prior to 

transmittal to NDEP and provide sufficient evidence that 

reasonable notice of a public hearing was provided to the public 

and that a public hearing was conducted prior to adoption. 

NDEP’s May 27, 2014 submittal of Clark County’s amended 

fugitive dust rules includes documentation of the public process 

used by Clark County to adopt the changes, including publication 
This document is a prepublication version, signed by EPA Region 9 Acting Regional Administrator Alexis Strauss on June 27, 

2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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of notice of a 30-day public review and comment period (February 

22, 2014 – March 25, 2014) and related public hearing in a 

newspaper of general circulation. As documented in the 

submittal, Clark County Board of County Commissioners adopted 

the amendments on April 15, 2014, effective April 29, 2014. 

Based on the documentation included in NDEP’s submittals, 

discussed above, we find that the submittals of the Las Vegas 

Valley PM10 Maintenance Plan and the amended fugitive dust rules 

as SIP revisions satisfy the procedural requirements of sections 

110(a) and 110(l) of the Act for revising SIPs. 

IV. Substantive Requirements for Redesignation 

The CAA establishes the requirements for redesignation of a 

nonattainment area to attainment. Specifically, section 

107(d)(3)(E) allows for redesignation provided that the 

following criteria are met: (1) EPA determines that the area has 

attained the applicable NAAQS; (2) EPA has fully approved the 

applicable implementation plan for the area under section 

110(k); (3) EPA determines that the improvement in air quality 

is due to permanent and enforceable reductions in emissions 

resulting from implementation of the applicable SIP, applicable 

federal air pollution control regulations, and other permanent 

and enforceable reductions; (4) EPA has fully approved a 

maintenance plan for the area as meeting the requirements of CAA 

section 175A; and (5) the State containing such area has met all 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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requirements applicable to the area under section 110 and part D 

of the CAA. 

EPA provided guidance on redesignations in a document 

titled, “State Implementation Plans; General Preamble for the 

Implementation of Title I of the Clean Air Act Amendments of 

1990,” published in the Federal Register on April 16, 1992 (57 

FR 13498), and supplemented on April 28, 1992 (57 FR 18070). 

Other relevant EPA guidance documents include: “Procedures for 

Processing Requests to Redesignate Areas to Attainment,” 

Memorandum from John Calcagni, Director, Air Quality Management 

Division, EPA Office of Air Quality Planning and Standards, 

September 4, 1992 (referred to herein as the “Calcagni memo”); 

“Part D New Source Review (part D NSR) Requirements for Areas 

Requesting Redesignation to Attainment,” Memorandum from Mary D. 

Nichols, Assistant Administrator for Air and Radiation, October 

14, 1994; and “State Implementation Plans for Serious PM10

Nonattainment Areas, and Attainment Date Waivers for PM10

Nonattainment Areas Generally; Addendum to the General Preamble 

for the Implementation of title I of the Clean Air Act 

Amendments of 1990,” 59 FR 41998 (August 16, 1994). 

For the reasons set forth below in section V of this 

document, we propose to approve NDEP’s request for redesignation 

of the Las Vegas Valley PM10 nonattainment area to attainment for 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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the 24-hour PM10 NAAQS based on our conclusion that all of the 

criteria under CAA section 107(d)(3)(E) have been satisfied. 

V. Evaluation of the State's Redesignation Request for the Las 

Vegas Valley PM10 Nonattainment Area 

A. Determination That the Area Has Attained the PM10 NAAQS. 

CAA section 107(d)(3)(E)(i) states that, for an area to be 

redesignated to attainment, EPA must determine that the area has 

attained the relevant NAAQS. In this case, the relevant NAAQS is 

the PM10 NAAQS. As noted above, in 2010, EPA determined that the 

Las Vegas Valley nonattainment area attained the PM10 standard by 

the area’s applicable attainment date of December 31, 2006 based 

on data for years 2004-2006. Today’s action updates this 

determination based on the most recent available PM10 monitoring 

data.

Generally, EPA determines whether an area’s air quality is 

meeting the 24-hour PM10 NAAQS based upon complete,5 qualityassured, and certified data gathered at established state and 

local air monitoring stations (SLAMS) in the nonattainment area 

and entered into the EPA Air Quality System (AQS) database. EPA 

will consider air quality data from air monitoring stations 

other than SLAMS in the nonattainment area provided those 

stations meet the federal monitoring requirements for SLAMS, 

 

5 For PM10, a complete set of data includes a minimum of 75 percent of the 

scheduled PM10 samples per quarter. See 40 CFR part 50, Appendix K, section 

2.3(a). 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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including the quality assurance and quality control criteria in 

40 CFR part 58, appendix A. See 40 CFR 58.20; 71 FR 61236, 

61242; (October 17, 2006). 

Data from air monitors operated by state, local, or tribal 

agencies in compliance with EPA monitoring requirements must be 

submitted to AQS. These monitoring agencies certify annually 

that these data are accurate to the best of their knowledge. 

Accordingly, EPA relies primarily on data in AQS when 

determining the attainment status of an area. See 40 CFR 50.6; 

40 CFR part 50, appendices J and K; 40 CFR part 53; and, 40 CFR 

part 58, appendices A, C, D, and E. All valid data are reviewed 

to determine the area’s air quality status in accordance with 40 

CFR part 50, appendix K. 

Attainment of the 24-hour PM10 standard is determined by 

calculating the expected number of exceedances of the standard 

in a year. The 24-hour PM10 standard is attained when the 

expected number of exceedances averaged over a three-year period 

is less than or equal to one at each monitoring site within the 

nonattainment area. Three consecutive years of air quality data 

are required to show attainment of the 24-hour PM10 standard. See

40 CFR part 50 and appendix K. More than three years may be 

considered if all additional representative years of data 

meeting the 75 percent criterion are utilized. Data not meeting 

these criteria may also suffice to show attainment; however, 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

22 

such exceptions must be approved by the appropriate Regional 

Administrator in accordance with EPA guidance. See 40 CFR part 

50, appendix K, section 2.3. 

Clark County DAQ is responsible for monitoring ambient air 

quality within Clark County. Clark County submits annual 

monitoring network plans to EPA. These network plans describe 

the monitoring network operated by Clark County DAQ within Clark 

County. These plans discuss the status of the air monitoring 

network, as required under 40 CFR 58.10. 

EPA regularly reviews these annual plans for compliance 

with the applicable reporting requirements in 40 CFR part 58. 

With respect to PM10, EPA has found that the area’s network plans 

meet the applicable reporting requirements under 40 CFR part 58.6

EPA also concluded from its 2012 Technical System Audit that 

Clark County DAQ’s monitoring network currently meets or exceeds 

the requirements for the minimum number of SLAMS for PM10 in the 

Las Vegas Valley nonattainment area.7 Clark County DAQ annually 

 

6 See, e.g., letter from Meredith Kurpius, Manager, Air Quality Analysis 

Office, EPA Region IX, to Phil Wiker, Engineering Manager, Clark County DAQ, 

dated December 11, 2013, approving the relevant portions of Clark County 

DAQ’s 2013 Annual Network Plan. 

7 See EPA Region IX, Technical System Audit Report, Clark County Department 

of Air Quality Ambient Air Monitoring Program, July 26-July 27, 2012, Final 

report, July 2013, page 8. Enclosed with letter from Deborah Jordan, 

Director, Air Division, U.S. EPA Region IX, to Lewis Wallenmeyer, Clark 

County DAQ (August 1, 2013). 
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certifies that the data it submits to AQS are complete and 

quality-assured.8

During the 2004-2006 period, Clark County DAQ operated 13 

PM10 SLAMS monitoring sites within Las Vegas Valley. See 75 FR 

45485, at 45488 (August 3, 2010). Between 2006 and 2009, four of 

the sites were closed or stopped monitoring PM10. In 2010, Clark 

County DAQ discontinued PM10 monitoring at three more sites: 

Lone Mountain (northwest Las Vegas), Orr School (centralsoutheast Las Vegas), and Craig Road (North Las Vegas).9

Notwithstanding the decrease in the number of PM10 monitoring 

sites, Clark County DAQ continues to meet EPA requirements for 

the minimum number of PM10 monitoring sites in Clark County. 

In 2012, Clark County DAQ established a new PM10 monitoring 

site,10 and thus, at the present time, Clark County DAQ operates 

seven PM10 SLAMS monitoring sites within Las Vegas Valley: Green 

Valley (Henderson), J.D. Smith School (North Las Vegas), Joe 

Neal (northwest Las Vegas), Paul Meyer Park (southwest Las 

Vegas), Palo Verde School (west Las Vegas), Sunrise Acres School 

 

8 See, e.g., letter from Lewis Wallenmeyer, Clark County DAQ, to Fletcher 

Clover, Air Quality Analysis Office, EPA Region IX, certifying 2013 ambient 

air quality data and quality assurance data (April 22, 2014). 

9 EPA has approved Clark County DAQ’s discontinuation of PM10 monitoring at 

these sites. See letter from Matthew Lakin, U.S. EPA Region IX, to Mike 

Sword, Clark County DAQ (June 5, 2013)(Lone Mountain and Orr sites), and 

letter from Meredith Kurpius, U.S. EPA Region IX, to Mike Sword, Clark County 

DAQ (October 30, 2013)(Craig Road site). 

10 The new site is the Jerome Mack site, AQS ID: 32-003-0540. In addition, in 

2013, the Las Vegas Paiute tribe began monitoring for PM10 at an eighth site 

within the Las Vegas Valley PM10 nonattainment area. This eighth site has not 

been approved by EPA for NAAQS compliant monitoring.
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(central Las Vegas), and Jerome Mack (east Las Vegas).11 All 

seven sites monitor PM10 concentrations on a continuous, yearround basis using beta attenuation methods. See Clark County 

DAQ’s Annual Monitoring Network Plan Report (June 2013). Each of 

these methods has been granted the Federal Equivalent Method 

(FEM) designation by EPA. The PM10 monitoring sites have been 

established to monitor for population exposure in the middle or 

neighborhood scale.12

Consistent with the requirements contained in 40 CFR part 

50, EPA has reviewed the quality-assured and certified PM10

ambient air monitoring data as recorded in AQS for the 

applicable monitoring period collected at the monitoring sites 

in the Las Vegas Valley nonattainment area and determined that 

the data are of sufficient completeness for the purposes of 

making comparisons with the PM10 standards. 

EPA’s review of monitoring data for the PM10 standard for 

Las Vegas Valley includes exceedances of the standard recorded 

during the 2011-2013 time period. However, EPA is excluding the 

exceedances of the standard in 2011 from the attainment 

determination presented herein because they were the result of 

 

11 Figure 2-1 of the Las Vegas Valley PM10 Maintenance Plan illustrates the 

locations of Clark County DAQ PM10 monitoring sites (other than Jerome Mack). 

12 In this context, “middle scale” refers to conditions characteristic of 

areas from 100 meters to half a kilometer, and “neighborhood scale” refers to 

conditions throughout some reasonably homogeneous urban sub-region with 

dimensions of a few kilometers. See 40 CFR part 58, appendix D, section 4.6. 
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an exceptional event. On April 16, 2014 Clark County DAQ 

submitted a demonstration for a high wind PM10 exceptional event 

covering the two exceedances recorded on July 3, 2011 at the 

J.D. Smith and Sunrise Acres monitoring sites. EPA reviewed the 

documentation that Clark County DAQ provided to demonstrate that 

the exceedances on these days meet the criteria for an 

exceptional event under EPA’s Exceptional Events Rule (EER).13

EPA concurred with Clark County DAQ’s request for exceptional 

event determination that, based on the weight of evidence, the 

two exceedances were caused by a high wind exceptional event.14

Accordingly, EPA has determined that the monitored exceedances 

associated with this exceptional event should be excluded from 

use in determinations of exceedances and violations, including 

the evaluation of whether Las Vegas Valley has attained the 

standard for the purposes of redesignation under CAA section 

107(d)(3)(E)(i). 

Table 1 below shows the maximum 24-hour PM10 concentrations 

monitored at the seven PM10 sites over the most recent three-year 

period (2011-2013) and lists the calculated expected exceedances 

per year at each of the sites over that same period. As shown in 

table 1 below, exceedances were monitored at four of the sites 

in 2012, and at all of the sites in 2013. All of the exceedances 

 

13 40 CFR 50.1(j), (k), (l); 50.14; 51.930. 

14 See letter from Jared Blumenfeld, EPA Region IX, to Lewis Wallenmeyer, 

Clark County DAQ, dated June 25, 2014. 
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in 2012 were recorded on May 10, 2012, and all of the 

exceedances in 2013 were recorded on two days, April 15 and 

October 28, 2013. Clark County DAQ has flagged these exceedances 

as exceptional events. As noted above in connection with the 

2011 exceedances, if EPA concurs on exceedances as exceptional 

events, they are excluded from the determination of whether the 

area is attaining the NAAQS, but EPA has not taken action to 

concur on any of the exceedances in 2012 or 2013, and thus, the 

2012 and 2013 exceedances are not being excluded from today’s 

evaluation. 

TABLE 1—SUMMARY OF LAS VEGAS VALLEY PM10 MONITORING DATA, 2011-

2013 

Monitoring 

Site 

(AQS Monitor 

ID) 

Highest 24-hour 

PM10 concentration 

(μg/m3) 

2nd Highest 24-

hour PM10

concentration 

(μg/m3) 

Expected 

Exceedances 

per year 

2011 2012 2013 2011 2012 2013 2011-2013 

Green Valley 

(32-003-0298) 143 145 196 82 125 88 0.3 

J.D. Smith 

(32-003-2002) 71 203 237 66 82 169 1.0 

Jerome Mack 

(32-003-0540) NA 228 243 NA 138 121 0.7a

Joe Neal 

(32-003-0075) 130 182 226 100 88 131 0.7 

Palo Verde 

(32-003-0073) 89 138 212 43 94 119 0.3 

Paul Meyer 

(32-003-0043) 103 147 164 62 139 74 0.3 

Sunrise Acres

(32-003-0561) 85 211 267 66 81 136 0.7 

Note: Bold values represent exceedances of the 150 μg/m3 NAAQS. 

Violations occur when the “expected exceedances per year” 

averaged over a three-year period exceed 1.0. 
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NA = Not applicable. The Jerome Mack site opened in 2012. 

aThe listed design value is not valid because it does not meet 

completeness requirements

Source: Letter and attachments from Lewis Wallenmeyer, Clark 

County DAQ, to Fletcher Clover, Air Quality Analysis 

Office, EPA Region IX, certifying 2013 ambient air 

quality data and quality assurance data (April 22, 

2014). 

Based on a review of air quality data during the most 

recent complete three-year period (2011-2013)(summarized above 

in table 1) and without excluding the 2012 or 2013 exceedances, 

we find that the expected number of exceedances per year for Las 

Vegas Valley is 1.0 days per year (based on the J.D. Smith 

monitoring site). The 24-hour PM10 standard is attained when the 

expected number of exceedances averaged over a three-year period 

is less than or equal to one at each monitoring site within the 

nonattainment area. Therefore, we find that, based on complete, 

quality-assured, and certified data for three most recent years 

(2011-2013) that the Las Vegas Valley PM10 nonattainment area has 

attained the 24-hour PM10 standard. SLAMS data for 2014 are not 

yet available from these monitoring sites but will be reviewed 

prior to final action to ensure that they are consistent with 

continued attainment. 

B. The Area Must Have a Fully Approved SIP Meeting Requirements 

Applicable for Purposes of Redesignation under Section 110 and 

Part D. 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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Section 107(d)(3)(E)(ii) and (v) require EPA to determine 

that the area has a fully-approved applicable SIP under section 

110(k) that meets all applicable requirements under section 110 

and part D for the purposes of redesignation. 

1. Basic SIP Requirements under CAA Section 110 

Section 110(a)(2) sets forth the general elements that a 

SIP must contain in order to be fully approved. Although section 

110(a)(2) was amended in 1990, a number of the requirements did 

not change in substance, and therefore, EPA believes that the 

pre-amendment EPA-approved SIP met these requirements in Clark 

County with respect to PM10. As to those requirements that were 

amended, (see 57 FR 27936 and 27939, June 23, 1992), many are 

duplicative of other requirements of the Act. 

On numerous occasions over the past 38 years, NDEP has 

submitted, and we have approved, provisions addressing the basic 

CAA section 110 provisions. The Clark County portion of the 

approved Nevada SIP contains enforceable emission limitations; 

requires monitoring, compiling and analyzing of ambient air 

quality data; requires preconstruction review of new or modified 

stationary sources; provides for adequate funding, staff, and 

associated resources necessary to implement its requirements; 

and provides the necessary assurances that the State maintains 

responsibility for ensuring that the CAA requirements are 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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satisfied in the event that Clark County is unable to meet its 

CAA obligations.15 

There are no outstanding or disapproved applicable SIP 

submittals with respect to the Clark County portion of the SIP 

that prevent redesignation of the Las Vegas Valley PM10

nonattainment area for the 24-hour PM10 standard.16 Therefore, we 

 

15 The applicable SIP for NDEP and Clark County may be found at 

http://yosemite.epa.gov/r9/r9sips.nsf/allsips?readform&state=Nevada. We note 

that SIPs must be fully approved only with respect to applicable requirements 

for purposes of redesignation in accordance with section 107(d)(3)(E)(ii). 

Thus, for example, CAA section 110(a)(2)(D) requires that SIPs contain 

certain measures to prevent sources in a state from significantly 

contributing to air quality problems in another state. However, the section 

110(a)(2)(D) requirements for a state are not linked with a particular 

nonattainment area’s designation and classification in that state. EPA 

believes that the requirements linked with a particular nonattainment area’s 

designation and classification are the relevant measures to evaluate in 

reviewing a redesignation request. The transport SIP submittal requirements, 

where applicable, continue to apply to a state regardless of the designation 

of any one particular area in the state. 

Thus, we do not believe that these requirements should be construed to be 

applicable requirements for purposes of redesignation. In addition, EPA 

believes that the other section 110 elements not connected with nonattainment 

plan submissions and not linked with an area’s attainment status are not 

applicable requirements for purposes of redesignation. The State will still 

be subject to these requirements after Las Vegas Valley is redesignated. The 

section 110 and part D requirements, which are linked with a particular 

area’s designation and classification, are the relevant measures to evaluate 

in reviewing a redesignation request. This policy is consistent with EPA’s 

existing policy on applicability of conformity (i.e., for redesignations) and 

oxygenated fuels requirement. See Reading, Pennsylvania, proposed and final 

rulemakings 61 FR 53174-53176 (October 10, 1996), 62 FR 24826 (May 7, 1997); 

Cleveland-Akron-Lorain, Ohio, final rulemaking 61 FR 20458 (May 7, 1996); and 

Tampa, Florida, final rulemaking 60 FR 62748 (December 7, 1995). See also the 

discussion of this issue in the Cincinnati redesignation at 65 FR 37890 (June 

19, 2000), in the Pittsburgh redesignation at 66 FR 53099 (October 19, 2001), 

and in the Los Angeles redesignation at 72 FR 6986 (February 14, 2007) and 72 

FR 26718 (May 11, 2007). EPA believes that section 110 elements not linked to 

the area’s nonattainment status are not applicable for purposes of 

redesignation.

16 In 2012, EPA took final limited approval and limited disapproval action on 

updated new source review (NSR) rules adopted by Clark County and submitted 

as a revision to the Nevada SIP (77 FR 64039, October 18, 2012) and issued a 

partial approval and partial disapproval of Nevada’s “infrastructure” SIP for 

the 1997 8-hour ozone NAAQS and the 1997 and 2006 PM2.5 NAAQS (77 FR 64737, 

October 23, 2012). While these two final rules are not full approvals, they 

do not represent an obstacle to redesignation of the Las Vegas Valley PM10
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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find that NDEP and Clark County have met all SIP requirements 

for Clark County applicable for purposes of redesignation under 

section 110 of the CAA (General SIP Requirements). 

2. SIP Requirements under Part D 

Part D Requirements Other Than NSR or Conformity 

Subparts 1 and 4 of part D, title I of the CAA contain air 

quality planning requirements for PM10 nonattainment areas. 

Subpart 1 contains general requirements for all nonattainment 

areas of any pollutant, including PM10, governed by a NAAQS. The 

subpart 1 requirements include, in relevant part, provisions for 

emissions inventories, reasonable further progress (RFP), a 

program for preconstruction review and permitting of new or 

modified major stationary sources (“New Source Review,” or NSR), 

contingency measures, and conformity. 

Subpart 4 contains specific SIP requirements for PM10

nonattainment areas. The requirements set forth in CAA sections 

189(a), (c), and (e) apply specifically to “moderate” PM10

nonattainment areas and include, in relevant part: (1) 

provisions for implementation of reasonably available control 

measures (RACM); (2) quantitative milestones demonstrating RFP 

 

nonattainment area because the “infrastructure” SIP elements that EPA 

disapproved are not related to the nonattainment SIP requirements for the Las 

Vegas Valley PM10 nonattainment area and thus are not relevant for the 

purposes of redesignation and because, notwithstanding the limited approval 

and limited disapproval of the amended NSR rules, the Clark County DAQ NSR 

rules continue to meet the fundamental SIP requirements for NSR in “serious” 

PM10 nonattainment areas. 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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toward attainment by the applicable attainment date; and (3) 

provisions to ensure that the control requirements applicable to 

major stationary sources of PM10 also apply to major stationary 

sources of PM10 precursors except where EPA has determined that 

such sources do not contribute significantly to PM10 levels that 

exceed the NAAQS in the area. Under CAA section 189(b), 

“serious” PM10 nonattainment areas, such as Las Vegas Valley, 

must meet the “moderate” area requirements discussed above and, 

in addition, must develop and submit an attainment demonstration 

as well as provisions to assure the implementation of best 

available control measures (BACM) for the control of PM10. 

As noted previously, in 2004, EPA approved the PM-10 State 

Implementation Plan for Clark County (June 2001) (“Las Vegas 

Valley PM10 Attainment Plan”) as a revision to the Nevada SIP. 

See 69 FR 32273 (June 9, 2004). The Las Vegas Valley PM10

Attainment Plan was developed to meet the SIP requirements for 

“serious” PM10 nonattainment areas under subparts 1 and 4 of part 

D, except those related to NSR or conformity. More specifically, 

as part of our 2004 final action, EPA approved the Las Vegas 

Valley PM10 Attainment Plan as meeting the following 

requirements: baseline and projected emissions inventories as 

required under CAA section 172(c)(3); the demonstration that the 

plan provides for RFP and quantitative milestones as required 

under CAA sections 172(c)(2) and 189(c); the contingency 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

32 

measures as required under CAA section 172(c)(9); the 

demonstration that major sources of PM10 precursors such as 

nitrogen oxides and sulfur dioxide do not significantly 

contribute to violations of the PM10 standards as provided in CAA 

section 189(e); the attainment demonstration under CAA sections 

189(b)(1)(A); and the demonstration that the plan provides for 

implementation of BACM as required under CAA section 

189(b)(1)(B). Because the demonstration of BACM subsumes the 

demonstration of RACM, a separate analysis to determine if the 

measures represent a RACM level of control was not necessary. 

EPA’s approval of the BACM demonstration in the Las Vegas Valley 

PM10 Attainment Plan, therefore, also represented a finding that 

the plan provides for the implementation of RACM as required 

under CAA section 189(a)(1)(C). See 69 FR 32273 (June 9, 2004). 

Thus, for the reasons given above, and excluding NSR and 

conformity, which we address separately below, we find that 

Clark County has a fully-approved PM10 SIP with respect to the 

part D requirements for RACM, BACM, and other serious PM10 area 

SIP requirements. 

Permits for New and Modified Major Stationary Sources 

To meet the requirements of CAA sections 172(c)(5) and 

189(a)(1)(A), states must submit SIP revisions that meet the 

requirements under 40 CFR 51.165 (“Permit requirements”). Under 

40 CFR 51.165, states are required to submit SIP revisions that 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

33 

establish certain requirements for new or modified stationary 

sources in nonattainment areas, including provisions to ensure 

that major new sources or major modifications of existing 

sources of nonattainment pollutants incorporate the highest 

level of control, referred to as the Lowest Achievable Emission 

Rate (LAER), and that increases in emissions from such 

stationary sources are offset so as to provide for reasonable 

further progress towards attainment in the nonattainment area. 

See CAA section 173(a)(1)(A) and 40 CFR 51.165(a)(9)(ii)(A). 

The process for reviewing permit applications and issuing 

permits for new or modified stationary sources of air pollution 

is referred to as “New Source Review” (NSR). With respect to 

nonattainment pollutants in nonattainment areas, this process is 

referred to as “nonattainment NSR.” With respect to pollutants 

for which an area is designated as attainment or unclassifiable, 

states are required to submit SIP revisions that ensure that 

major new stationary sources and major modifications of existing 

stationary sources meet the Federal requirements for Prevention 

of Significant Deterioration (PSD), including application of 

“best available control technology,” for each applicable 

pollutant emitted in significant amounts, among other 

requirements. 

Within the Las Vegas PM10 nonattainment area, two agencies 

are responsible for meeting the requirements for nonattainment 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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NSR and PSD: NDEP and Clark County DAQ. Under Nevada law, 

exclusive NDEP jurisdiction extends to specific electric steamgenerating emission units (i.e., power plants) throughout the 

State of Nevada, and thus, state regulations govern air 

pollution permits issued to those types of units within Clark 

County. Clark County DAQ is responsible for all other stationary 

source emissions units within Clark County, and Clark County 

regulations govern air pollutant permits issued to them. 

With respect to those sources that are under State 

jurisdiction, we have approved a State rule (Nevada 

Administrative Code (NAC) section 445B.22083) that prohibits new 

power plants or major modifications to existing power plants 

under State jurisdiction within the Las Vegas Valley 

nonattainment area. See 69 FR 31056, 31059 (June 2, 2004) and 69 

FR 54006, at 54017 (September 7, 2004). In 2008, we approved an 

amended version of NAC section 445B.22083 that clarifies the 

application of NSR requirements to any relocation of power 

generating units. See 73 FR 20536 (April 16, 2008). The 

submittal and approval of the State’s prohibition on new major 

power plants or major modifications to existing power plants in 

Las Vegas Valley adequately substitutes for submittal and 

approval of a SIP revision meeting nonattainment NSR 

requirements in Las Vegas Valley with respect to sources under 

NDEP jurisdiction. 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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With respect to sources under Clark County DAQ 

jurisdiction, we approved Clark County’s NSR rules as meeting 

the requirements of section 172(c)(5) and, for PM10, section 

189(a)(1)(A). See 69 FR 54006 (September 7, 2004); also, see our 

proposed rule at 69 FR 31056, at 31059 (June 2, 2004) for 

details on how Clark County’s NSR rules complied with CAA 

requirements for PM10 nonattainment areas. In recent years, Clark 

County DAQ has adopted comprehensive changes to its NSR program 

and, in 2012, EPA issued a limited approval and limited 

disapproval for the revised program. See 77 FR 64039 (October 

18, 2012). With respect to nonattainment NSR, EPA found a number 

of deficiencies; however, the Clark County NSR rules continue to 

meet the basic requirements for a serious PM10 nonattainment NSR 

area, including a definition of “major stationary source” as a 

stationary source which emits, or has the potential to emit, 

seventy (70) tons per year or more of PM10, emissions limitations 

that constitute LAER, and emissions reductions to offset 

emissions increases that would otherwise occur.17 See Clark 

County section 12.3.2 (“Definitions,” subsection (y) “Major 

Stationary Source”); 12.3.5.2 (“Permit Requirements to Achieve 

LAER”); and 12.3.6 (“Emissions Offset”). 

 

17 The deficiencies that have any bearing on PM10 are limited to a few 

definitions: “allowable emissions,” “baseline actual emissions,” “net 

emissions increase,” and “major modification.” See 77 FR 64039, at 64047 

(October 18, 2012). 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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Moreover, Clark County’s SIP-approved NSR rules have served 

as a federally-enforceable constraint on the growth of 

stationary source emissions, and thus have supported the 

region’s efforts to lower ambient PM10 concentrations in Las 

Vegas Valley. Therefore, given the prohibition on new sources or 

major modifications of existing sources under NDEP jurisdiction 

and given that the fundamental nonattainment NSR requirements 

are approved into the SIP for sources under Clark County DAQ 

jurisdiction, we conclude that the State has met the applicable 

NSR requirements for the Las Vegas PM10 nonattainment area for 

the purposes of redesignation of the area to attainment for the 

PM10 standard. 

General and Transportation Conformity Requirements 

Under section 176(c) of the Clean Air Act Amendments of 

1990, States are required to establish criteria and procedures 

to ensure that Federally supported or funded projects conform to 

the air quality planning goals in the applicable SIP. Section 

176(c) further provided that State conformity provisions must be 

consistent with Federal conformity regulations that the CAA 

required EPA to promulgate. EPA’s conformity regulations are 

codified at 40 CFR part 93, subparts A (referred to herein as 

“transportation conformity”) and B (referred to herein as 

“general conformity”). Transportation conformity applies to 

transportation plans, programs, and projects developed, funded, 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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and approved under title 23 U.S.C. or the Federal Transit Act, 

and general conformity applies to all other Federally-supported 

or funded projects. SIP revisions intended to address the 

conformity requirements are referred to herein as “conformity 

SIPs.” 

In November 2008, EPA approved Clark County’s 

transportation conformity criteria and procedures as meeting the 

related SIP requirements under part 51, subpart T (“Conformity 

to State or Federal Implementation Plans of Transportation 

Plans, Programs, and Projects Developed, Funded or Approved 

Under Title 23 U.S.C. or the Federal Transit Laws”). See 73 FR 

66182 (November 7, 2008). 

In August 2005, Congress passed the Safe, Accountable, 

Flexible, Efficient Transportation Equity Act: A Legacy for 

Users (SAFETEA-LU), which eliminated the requirement for States 

to adopt and submit conformity SIPs addressing general 

conformity requirements. See 75 FR 17254 (April 5, 2010) for 

conforming changes to EPA’s general conformity regulations. 

Based on our approval of Clark County’s transportation 

conformity SIP and SAFETEA-LU’s elimination of the general 

conformity SIP requirement, we find that Clark County and the 

State have met the requirements for conformity SIPs in the Las 

Vegas Valley PM10 nonattainment area under CAA section 176(c). In 

any event, EPA believes it is reasonable to interpret the 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

38 

conformity requirements as not applicable for purposes of 

evaluating a redesignation request under section 107(d)(3)(E). 

See Wall v. EPA, 265 F.3d 426, 439 (6th Cir. 2001) upholding 

this interpretation. 

3. Conclusion With Respect To Sections 107(d)(3)(E)(ii) and (v) 

Thus, EPA finds, based on our review of EPA’s previous 

rulemakings on the relevant portions of the Nevada SIP and for 

the reasons provided above, that the Las Vegas Valley has a 

fully approved applicable SIP under section 110(k) that meets 

all applicable requirements under section 110 and part D for the 

purposes of redesignation, and thereby meets the criteria for 

redesignation under CAA sections 107(d)(3)(E)(ii) and (v). 

C. The Area Must Show the Improvement in Air Quality is Due to 

Permanent and Enforceable Emissions Reductions. 

Section 107(d)(3)(E)(iii) precludes redesignation of a 

nonattainment area to attainment unless EPA determines that the 

improvement in air quality is due to permanent and enforceable 

emissions reductions resulting from implementation of the 

applicable SIP and applicable Federal air pollution control 

regulations and other permanent and enforceable regulations. 

Under this criterion, the state must be able to reasonably 

attribute the improvement in air quality to emissions reductions 

which are permanent and enforceable. Attainment resulting from 

temporary reductions in emissions rates (e.g., reduced 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

39 

production or shutdown due to temporary adverse economic 

conditions) or unusually favorable meteorology would not qualify 

as an air quality improvement due to permanent and enforceable 

emission reductions. See the Calcagni memo, page 4. 

The Las Vegas Valley PM10 Maintenance Plan credits a number 

of local and Federal control measures for having reduced PM10

emissions and concentrations within Las Vegas Valley 

sufficiently to attain the NAAQS, and relies on their continued 

implementation to provide for maintenance of the NAAQS now that 

the NAAQS has been attained. The local control measures cited in 

the maintenance plan include certain Clark County Air Quality 

Regulations (AQR), such as the NSR rule (AQR section 12), the 

acid rain permit rule (AQR section 21), and the fugitive dust 

rules (AQR sections 90 through 94); best available retrofit 

technology to meet the requirements of EPA’s regional haze rule; 

the transportation conformity process; and the Clark County 

Natural Events Action Plan. Federal control measures cited in 

the maintenance plan include the National Emissions Standards 

for Hazardous Air Pollutants (NESHAPs) and Standards of 

Performance for New Stationary Sources (NSPS). 

While we agree that all of the measures cited above 

contributed to attainment and will contribute to maintenance of 

the PM10 NAAQS in Las Vegas Valley, the backbone of the control 

strategy that provided for attainment of the PM10 NAAQS was Clark 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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County’s section 90 series regulations governing fugitive dust 

sources. Clark County’s section 12 NSR rule and local ordinances 

(Clark County, and the cities of Las Vegas, North Las Vegas, and 

Henderson) regulating new fireplaces also contributed to 

attainment of the standard and will contribute to maintenance of 

the standard. 

In our approval of the BACM demonstration in the Las Vegas 

Valley PM10 Attainment Plan, we described the BACM analysis in 

terms of a series of steps intended to identify all of the 

sources or source categories that significantly contribute to 

exceedances of the NAAQS and to provide for implementation of 

BACM for all of those sources or source categories. Clark 

County’s approved BACM demonstration identified certain fugitive 

dust sources, including disturbed vacant land/unpaved parking 

lots, construction (including highway construction), paved 

roads, unpaved roads, and race tracks as the source categories 

that significantly contribute to exceedances of the PM10 NAAQS in 

Las Vegas Valley. See 68 FR 2954, at 2959 (January 22, 2003). In 

the approved Las Vegas Valley PM10 Attainment Plan, Clark County 

further demonstrated how Clark County AQR sections 90 through 94 

implemented BACM for the relevant source categories.18 EPA 

 

18 The 90 series rules include Clark County AQR section 90 (“Fugitive Dust 

from Open Areas and Vacant Lots”), section 91 (“Fugitive Dust from Unpaved 

Roads, Unpaved Alleys and Unpaved Easement Roads”), section 92 (“Fugitive 

Dust from Unpaved Parking Lots, Material Handling & Storage Yards, & Vehicle 

& Equipment Storage Yards”), section 93 (“Fugitive Dust from Paved Roads & 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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approved these regulations as part of the SIP at the same time 

that EPA approved the Las Vegas Valley PM10 Attainment Plan, 69 

FR 32273 (June 9, 2004), and since then, the Clark County 

fugitive dust regulations have been federally enforceable. Clark 

County’s section 12 NSR rule has been approved as part of the 

SIP, most recently at 77 FR 64039 (October 18, 2012), as have 

the local fireplace ordinances cited above, 68 FR 52838 

(September 8, 2003). 

We also note that Clark County’s 90 series regulations were 

implemented in the early 2000s, and a rough indication of their 

impact on ambient PM10 concentrations can be seen in figure 2-2 

in the Las Vegas Valley PM10 Maintenance Plan that shows a steep 

decline in design values19 for Las Vegas Valley from the late 

1990s beginning in 2002 to a level below the NAAQS beginning in 

2005. This improvement occurred despite a 30 percent increase in 

population in Las Vegas Valley during the same period.20 Thus, 

the improvement in air quality since 2000 may reasonably be 

attributed to implementation of Clark County’s 90 series (i.e., 

 

Street Sweeping Equipment”), and section 94 (“Permitting & Dust Control for 

Construction Activities”). 

19 In this context, the design value at each monitoring site refers to the 

first-, second-, third, or fourth-highest measured concentration (depending 

on the frequency of monitoring) over a three-year period. The highest design 

valley among the monitoring sites determines the design value for the 

nonattainment area. A design value for a given year reflects the data for 

that year and the previous two years. For example, a design value for 2002 

reflects 2000-2002 data. 

20 See population figures in table 4-1 of the Las Vegas Valley PM10

Maintenance Plan. 
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fugitive dust) rules. Moreover, while we recognize that annual 

rainfall during the 2003-2005 period in Las Vegas Valley was 

higher than normal, we note that the downward trend in 

concentrations began prior to that time and that maintenance of 

the NAAQS has continued since the mid-2000s despite lower-thannormal rainfall from 2006-2009.21 

Thus, we find that the improvement in air quality in the 

Las Vegas Valley PM10 nonattainment area is the result of 

permanent and enforceable emissions reductions from a 

combination of permanent and enforceable measures, including, 

but not limited to fugitive dust rules, the NSR rule, and 

fireplace ordinances, and is not the result of adverse economic 

conditions or unusual meteorological conditions. As such, we 

find that the criterion for redesignation set forth at CAA 

section 107(d)(3)(E)(iii) is satisfied. 

D. The Area Must Have a Fully-Approved Maintenance Plan under 

CAA Section 175A. 

Section 175A of the CAA sets forth the elements of a 

maintenance plan for areas seeking redesignation from 

nonattainment to attainment. Under CAA section 175A, a 

maintenance plan must demonstrate continued attainment of the 

applicable NAAQS for at least ten years after EPA approves a 

 

21 See section 4.3 of the Las Vegas Valley PM10 Maintenance Plan for wind and 

rainfall data in Las Vegas Valley. 
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redesignation to attainment. Eight years after redesignation, 

the State must submit a revised maintenance plan that 

demonstrates continued attainment for the subsequent ten-year 

period following the initial ten-year maintenance period. To 

address the possibility of future NAAQS violations, the 

maintenance plan must contain such contingency provisions as EPA 

deems necessary to promptly correct any violation of the NAAQS 

that occurs after redesignation of the area. 

To meet these requirements, maintenance plans should 

include the following core elements: attainment inventory, 

maintenance demonstration, continuation of an adequate 

monitoring network, verification of continued attainment, and 

contingency plan. See Calcagni memo, pages 8 through 13. Based 

on our review and evaluation of the plan, as detailed below, we 

are proposing to approve the Las Vegas Valley PM10 Maintenance 

Plan because we have found that it meets the requirements of CAA 

section 175A. 

1. Attainment Inventory 

A maintenance plan for the 24-hour PM10 standard must 

include an inventory of emissions of PM10 in the area to identify 

a level of emissions sufficient to attain the 24-hour PM10

NAAQS.22 This inventory must be consistent with EPA’s most recent 

 

22 PM10 precursor emissions may also be required depending upon the 

contribution of secondarily-formed particulate matter to ambient PM10

concentrations. As discussed in our proposed approval of the Las Vegas Valley 
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guidance on emissions inventories for nonattainment areas 

available at the time and should represent emissions during the 

time period associated with the monitoring data showing 

attainment. The inventory must also be comprehensive, including 

emissions from stationary point sources, area sources, nonroad 

mobile sources, and on-road mobile sources, and must be based on 

actual emissions during the appropriate season or episode, if 

applicable. In the following paragraphs, we summarize our 

findings with respect to the emissions inventories prepared for 

the Las Vegas Valley PM10 Maintenance Plan. 

First, emissions inventories for attainment or maintenance 

plans are generally developed for the entire nonattainment area. 

For the Las Vegas Valley PM10 Maintenance Plan, Clark County DAQ 

developed emissions inventories for a subset of the 

nonattainment area referred as to the BLM disposal area.23 See 

figure 1-1 in the Las Vegas Valley PM10 Maintenance Plan for a 

map showing the BLM disposal area in relation to the Las Vegas 

 

PM10 Attainment Plan, 68 FR 2958 (January 22, 2003), Clark County determined, 

based on analyses of inventories (see chapter 4, section 4.2.1 of the 

Attainment Plan) and Chemical Mass Balance modeling, that secondary 

particulate contributes less than significant amounts to ambient PM10

concentrations. Therefore, PM10 precursors, including oxides of nitrogen, 

sulfur dioxide and volatile organic compounds, are not included in the Las 

Vegas Valley PM10 Maintenance Plan, and we find their absence acceptable. 

23 The Las Vegas Valley PM10 Maintenance Plan explains that most of the land 

in Nevada is under federal jurisdiction, and most of the federal land is 

managed by the Bureau of Land Management (BLM). In 1998, Congress passed the 

Southern Nevada Public Land Management Act, which allowed BLM to sell, trade, 

or lease public land within a specific area around Las Vegas. There was an 

amendment to the boundary for this area in 2003, and minor adjustments 

thereafter. The area currently comprises approximately 327,000 acres and is 

known as the BLM disposal area. 
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Valley PM10 nonattainment area. EPA accepted the BLM disposal 

area as the geographic basis for the emissions inventories in 

the Las Vegas Valley PM10 Attainment Plan (see 68 FR 2954, at 

2958 (January 22, 2003), and we do so again for the Las Vegas 

Valley PM10 Maintenance Plan. The BLM disposal area remains an 

appropriate geographic basis for air quality planning purposes 

because more than 99 percent of the population within the 

nonattainment area lives within BLM disposal area, more than 98 

percent of the vehicle miles traveled within the nonattainment 

area occurs within the BLM disposal area, and nearly all of the 

anthropogenic sources within the nonattainment area are located 

within the BLM disposal area. 

Furthermore, most of the area within the nonattainment area 

but outside the BLM disposal area lies under the jurisdiction of 

the federal government, and all lands controlled by the federal 

government outside the BLM disposal area are to remain in their 

native or managed state. The disposal area boundary can only be 

changed by an act of Congress. Continued reliance on the BLM 

disposal area for air quality planning purposes was confirmed in 

2007 by a PM10 monitoring study conducted by Clark County DAQ 

under which samplers were deployed outside the BLM disposal 

area. No violations were recorded. We note that, while the 

inventory corresponds to the BLM disposal area, the regulations 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

46 

adopted by Clark County DAQ to address PM10 sources apply to the 

entire PM10 nonattainment area. 

Second, as to the year selected for attainment inventory 

purposes, Clark County DAQ selected year 2008 as the year for 

the attainment inventory in the Las Vegas Valley PM10 Maintenance 

Plan. Emissions during year 2008 are reflected in three threeyear periods that could be used to evaluate whether the area is 

attaining the standard: 2006-2008, 2007-2009, and 2008-2010. In 

the latter two periods, the expected number of exceedances 

averaged over the relevant three-year period was less than 1.0, 

which reflects attainment conditions. The period 2006-2008 has 

an expected number of exceedances of 1.1, which represents a 

violation of the standard; however, the value of 1.1 reflects 

two exceedances for which Clark County DAQ has flagged as 

exceptional events. Under these circumstances, we do not believe 

that the violation calculated for the 2006-2008 period should 

preclude the selection of 2008 for the inventory and find its 

selection by Clark County DAQ to be acceptable. 

Third, the emissions inventories developed by Clark County 

DAQ for the Las Vegas Valley PM10 Maintenance Plan reflect 

“design day” conditions. The specific day selected for emissions 

inventory purposes was April 15, 2008. Clark County DAQ selected 

that day based on a review of data from all of the PM10

monitoring sites that operated from 2008 through 2010 that 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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showed April 15, 2008 to be the day during which the highest PM10

concentration not unduly affected by high-wind events was 

measured. We find the use of a design day inventory, and 

selection of April 15, 2008 as the specific day for the 

inventory, to be acceptable. 

Fourth, as to comprehensiveness, we find that the emissions 

inventories in the maintenance plan to be comprehensive in that 

they include estimates of PM10 from all of the relevant source 

categories, which the plan divides among point sources,24

nonpoint sources,25 on-road mobile sources, nonroad mobile 

sources, and emission reduction credits. See table 6-2 of the 

Las Vegas Valley PM10 Maintenance Plan for a summary of the 

attainment inventory (2008), as well as future year emissions 

projections for years 2015 and 2023. Appendix A to the PM10

Maintenance Plan contains source-category-specific descriptions 

of emission calculation procedures and sources of input data. 

Table 2 below summarizes the attainment inventory (for 

2008) in the Las Vegas Valley PM10 Maintenance Plan, and also 

summarizes the plan’s projected emissions inventories for an 

interim year (2015) and the maintenance plan’s horizon year 

(2023). Based on the estimates in table 2, the nonpoint category 

 

24 “Point sources” refer to those stationary source facilities that are 

required to report their emissions to Clark County DAQ or NDEP. 

25 “Nonpoint sources” refer to those stationary and area sources that fall 

below point source reporting levels and that are too numerous or small to 

identify individually. 
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of emissions accounted for nearly 99% of the PM10, with wind 

erosion from vacant lands making up 62%, wind erosion from 

construction making up 26%, and paved road dust and construction 

emissions each making up 4% of the total PM10 inventory for 2008. 

TABLE 2: TOTAL DAILY LAS VEGAS VALLEY PM10 EMISSIONS, 2008, 2015, 

AND 2023

Category Subcategory 

PM10 (tons per day)a

2008 2015 2023

Point 

2.19 2.60 2.88 

Nonpoint

Wind Erosion 

(Vacant Lands) 439.05 288.16 122.77 

Wind Erosion 

(construction) 183.97 217.70 249.21 

Construction 30.93 37.69 41.22 

Paved Road 30.85 38.04 48.78 

Unpaved Road 5.84 6.51 7.49 

Other 6.59 7.24 7.89 

On-Road Motor 

Vehicles 3.08 2.52 2.75 

Nonroad 

Mobile 

Sources 

3.74 2.95 1.94 

Emission 

Reductions 

Credits 

0.31 0.31 0.31 

Totals 706.55 603.72 485.24 

a Emissions correspond to the BLM disposal Area portion of 

the Las Vegas Valley nonattainment area and reflect design 

day conditions. 
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Source: Derived from estimates in table 6-2 of the Las Vegas 

Valley PM10 Maintenance Plan. 

Lastly, we reviewed the methods, factors, and assumptions 

used by Clark County DAQ to develop the emissions inventories in 

the Las Vegas Valley PM10 Maintenance Plan to ensure that the 

inventories are consistent with EPA’s most recent guidance for 

such inventories. As noted above, Clark County DAQ’s inventory 

is divided into five broad categories (point sources, nonpoint 

sources, on-road mobile sources, nonroad mobile sources, and 

emission reduction credits). Multiple subcategories of emissions 

are calculated within each of these broad categories. 

For point sources, Clark County DAQ based the inventory 

estimates on source-reported actual 2008 emissions data. For 

nonpoint or area wide sources, Clark County calculated emissions 

based on county-wide reported data for fuel usage, product 

sales, population, employment data, land area, and other 

parameters covering a wide range of activities. The largest 

emission sources for the PM10 inventory, wind erosion from 

construction and wind erosion from vacant lands, are included in 

nonpoint emissions. These two source categories contribute over 

80% of the total PM10 emissions in 2008. Emission factors for 

windblown fugitives were developed based on a series of windtunnel studies conducted by University of Nevada, Las Vegas 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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(UNLV). These emission factors were combined with estimates of 

vacant land and developed land from the Clark County Department 

of Comprehensive Planning (DCP)’s Geographic Integrated Land Use 

Information System (GILIS). 

The nonroad mobile source category includes aircraft, 

boats, and off-road vehicles and equipment used for 

construction, farming, commercial, industrial, and recreational 

activities. With respect to such sources, Clark County DAQ used 

EPA’s nonroad emissions model NONROAD2008a, the current version 

of the model at the time the plan was created. The model 

includes both emissions factors and default county level 

population and activity data. The model estimates both emissions 

factors and emissions. This includes more than 80 basic and 260 

specific types of non-road equipment, and further stratifies 

equipment by horsepower rating and fuel type. The model has 

default estimates, variables and factors used in the 

calculations. No local data sets were available for Clark 

County, therefore only model defaults were used. 

The on-road mobile source category consists of trucks, 

automobiles, buses, and motorcycles. The on-road emissions 

inventory estimates in the Las Vegas Valley PM10 Maintenance Plan 

were prepared by Clark County DAQ using EPA’s Motor Vehicle 

Emissions Simulator (MOVES2010a) model and AP-42. The vehicle 

miles traveled were developed from vehicle activity data from 
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the Regional Transportation Commission of Southern Nevada (RTC) 

using the transportation demand model, TransCAD. 

The on-road emissions estimates for the Las Vegas Valley 

PM10 Maintenance Plan assumed the implementation of the federal 

heavy-duty diesel rule, limits to Reid Vapor Pressure (RVP) of 9 

pounds per square inch (PSI) with a 1.0 psi waiver for ethanolblended fuels, the phase-in of federal tier 2 motor vehicle 

emission standards, and the continuation of the SIP-approved 

enhanced vehicle inspection and maintenance (I/M) program in the 

urban areas of Clark County.26

Based on our review of the emissions inventories (and 

related documentation) from the Las Vegas Valley PM10 Maintenance 

Plan, we find that the inventory for 2008 is comprehensive, that 

the methods and assumptions used by Clark County to develop the 

emission inventory are reasonable, and that, therefore, the 2008 

inventory reasonably estimates actual PM10 emissions in an 

attaining year. Moreover, we find that the emissions inventory 

in the PM10 Maintenance Plan reflects the latest planning 

assumptions and emissions models available at the time the plan 

was developed, and provides a comprehensive and reasonably 

accurate basis upon which to forecast PM10 emissions for years 

2015 and 2023. 

 

26 The EPA’s most recent action on Nevada’s I/M program updated the 

corresponding State statutes and rules. 73 FR 38124 (July 3, 2008). 
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2. Maintenance Demonstration 

Section 175A(a) of the CAA requires a demonstration of 

maintenance of the NAAQS for 10 years after redesignation. A 

state may generally demonstrate maintenance of the NAAQS by 

either showing that future emissions of a pollutant or its 

precursors will not exceed the level of the attainment 

inventory, or by modeling to show that the future anticipated 

mix of sources and emission rates will not cause a violation of 

the NAAQS. See Calcagni memo, pages 9 through 11. 

The Las Vegas Valley PM10 Maintenance Plan includes 

emissions inventory projections for 2015 and 2023 and 

corresponding estimates of future-year design values to 

demonstrate maintenance through 2023. In doing so, Clark County 

DAQ relies on “rollback,” the scaling of measured concentrations 

proportional to emissions, with conservative assumptions for the 

rollback concentration target and for the background 

concentration. In this case, Clark County DAQ predicted future 

year design values by adjusting a 2008 design value by the 

proportional change in overall PM10 emissions from the attainment 

inventory (2008) relative to the inventories for the future 

years (2015 and 2023), taking into account a background level 

(on the design value day) of approximately 40 μg/m3. We find 

Clark County DAQ’s use of a “rollback” type of analysis 

appropriate in this case given that ambient PM10 concentrations 
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in Las Vegas Valley are driven primarily by ground-level direct 

PM10 emissions (in particular fugitive dust) with generally 

consistent dispersion characteristics. 

The foundation for the maintenance demonstration is the 

emissions projections for year 2015 and 2023 because, using the 

rollback method, the predicted future year design values will 

remain below the attainment-year design value (and thus below 

the NAAQS) if the emissions projections for the future years are 

less than the attainment-year inventory. In this case, Clark 

County DAQ identified 98 μg/m3 as the design value for 2008 (40 

μg/m3 of which represents the background as noted above). The 

design value of 98 μg/m3 excludes two exceedances measured in Las 

Vegas Valley in 2008 that were flagged and documented by Clark 

County DAQ as exceptional events. EPA has not taken action to 

concur, or not to concur, on the flagged exceedances, and if the 

two exceedances were taken into account (in determining the 

design value rather than being excluded), the design value for 

2008 would be 123 μg/m3, rather than 98 μg/m3. Regardless of 

whether the 2008 design value is be 123 μg/m3 or 98 μg/m3, the 

general principle still applies because both design values are 

well below the 24-hour PM10 NAAQS of 150 μg/m3. Namely, if the 

future-year emissions projections remain below the emissions 

estimated for the attainment year, then future-year 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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concentrations should remain below the design value for the 

attainment year and thus well below the NAAQS. 

Given the importance of the future-year emissions 

projections, EPA reviewed the methods and assumptions used by 

Clark County DAQ to adjust the attainment-year (2008) emissions 

inventory to develop emissions projections for 2015 and 2013, 

with particular attention paid to those source categories that 

contribute most to the overall inventory. The documentation for 

Clark County DAQ’s emissions projections are found in appendix A 

(“Technical Support Document”) to the Las Vegas Valley PM10

Maintenance Plan. 

One of the principle assumptions on which the maintenance 

plan is based is the continued implementation of Clark County’s 

fugitive dust rules, particularly the 90 series rules (i.e., 

sections 90 through 94). As approved into the SIP, these rules, 

other than section 94, apply within the “PM10 nonattainment 

area.” Redesignation to attainment would presumably have 

undercut continued implementation of the rules. However, Clark 

County has recently amended the rules to apply within a PM10

nonattainment area or an area subject to a PM10 maintenance plan, 

to ensure continued applicability after the area is redesignated 

attainment, and thus to be consistent with the assumptions of 

the maintenance demonstration in the Las Vegas Valley PM10

Maintenance Plan. Because EPA cannot redesignate a nonattainment 
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area to attainment without approval of a maintenance plan, see 

CAA section 107(d)(3)(E)(4), Clark County’s extension of 

applicability of the fugitive dust rules to areas subject to a 

maintenance plan ensures continued implementations of the rules 

after redesignation. In section VI of this document, we are 

proposing to approve the amended fugitive dust rules as a part 

of this action. 

As described in appendix A to the maintenance plan, Clark 

County DAQ relied primarily on growth factors generated by EPA’s 

Economic Growth Analysis System, Version 5 (EGAS); however, 

population forecasts were also used to estimate future-year 

emissions or activity throughput where applicable. With respect 

to population forecasts, Clark County DAQ relied on the most 

recent forecasts developed by the Center for Business and 

Economic Research (CBER) at the University of Nevada, Las Vegas 

(UNLV) using 2010 U.S. Census data. CBER forecasts a population 

increase from 2008 to 2015 of 8.6% and a population increase 

from 2008 to 2023 of 25%.27 Examples of source categories for 

which population forecasts were used to develop the emissions 

projections include construction, wind erosion, and unpaved road 

sectors. We find this approach to be acceptable. 

 

27 See page 2-1 of appendix A (“Technical Support Document”) to the Las Vegas 

Valley PM10 Maintenance Plan. 
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While EGAS growth factors were used for many source 

categories, other than those driven by population, Clark County 

DAQ declined to use EGAS factors for certain sources or source 

categories if more accurate local data were available. These 

source and source categories and related data sources include 

Nellis Air Force Base; fuel consumption projections from the 

U.S. Energy Information Agency; Union Pacific railroad 

operations; and vehicle miles traveled (VMT) projections from 

the Regional Transportation Commission of Southern Nevada (RTC) 

for use in estimating entrainment of PM10 from vehicle travel 

over paved roads.28 Clark County DAQ also included banked 

emissions reduction credits (ERCs) for 2015 and 2023 in the 

event that the ERCs are used for the purposes of issuing permits 

for new or modified stationary sources in the air quality 

planning area.29 We find these data sources to be appropriate for 

use in developing emissions projections for the maintenance 

plan. 

Representing approximately 62% of the overall inventory, 

wind erosion over vacant lands represents the single largest 

source category in terms of its contribution to the overall PM10

inventory for year 2008 for the BLM disposal area. Clark County 

DAQ estimated that emissions from this category would decline 

 

28 See page 4-13 of appendix A (“Technical Support Document”) to the Las 

Vegas Valley PM10 Maintenance Plan. 

29 See Las Vegas Valley PM10 Maintenance Plan, section 6.4.4. 
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from approximately 440 tons per day in 2008 to 290 tons per day 

by 2015 and then to 123 tons per day by 2023. Given this 

significant predicted decrease in emissions relative to existing 

conditions, EPA reviewed in detail the assumptions and basis for 

these forecasts. 

As described in section 5.2 of appendix A to the Las Vegas 

Valley PM10 Maintenance Plan, the emissions projections for wind 

erosion from vacant lands were made using emissions factors that 

were developed based on a series of wind-tunnel studies 

conducted by UNLV, combined with soil inventory data based on 

satellite imagery and estimates of vacant land and developed 

land from the Clark County Department of Comprehensive Planning 

(DCP)’s Geographic Integrated Land Use Information System 

(GILIS), adjusted over time based on a vacant land consumption 

rate of approximately 3,400 acres per year and projected 

population growth rates. The rate for vacant land consumption 

from 2011 to 2023 is projected to be approximately 23% less than 

the 30-year average vacant land consumption rate (approximately 

4,400 acres per year). The decrease in emissions projected for 

the wind erosion over vacant lands reflects the reduction in 

total disturbed unstable lands within the BLM disposal area from 

approximately 10,100 acres in 2008 to 8,200 acres in 2015 and 

then to 6,100 acres in 2023. We believe Clark County DAQ’s 

approach to projecting emissions from this source category to be 
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reasonable and find that projected decrease in emissions from 

this source category is logical given the extent to which the 

lands within the BLM disposal area are already developed or 

remain as native desert. 

Based on our review described above, we find that the 

methods, growth factors, and assumptions used by Clark County 

DAQ to project emissions in 2015 and 2023 based on the 

attainment inventory for 2008 are reasonable. Given that the 

projections (summarized in table 2 above) show future emissions 

in 2015 (603.72 tons per day) and 2023 (485.24 tons per day) to 

be well below those in 2008 (706.55 tons per day), we find that 

the projections provide an adequate basis to demonstrate 

maintenance of the PM10 NAAQS within the Las Vegas Valley area 

through 2023. Also, as described further in section V.D.7 of 

this document, Clark County DAQ has chosen to include “safety 

margins” in the motor vehicle emissions budgets for 2015 (90.63 

tons per day) and 2023 (78.29 tons per day), but we find that 

the overall emissions projections, including the safety margins 

for the budgets, for 2015 (694.35 tons per day) and 2023 (563.53 

tons per day) remain below those in 2008 (706.55 tons per day), 

and thus, the safety margins are consistent with maintenance of 

the NAAQS through 2023. 

Lastly, we note that, under CAA section 175A(a), a 

maintenance plan must provide for maintenance of the NAAQS in 
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the area “for at least 10 years after the redesignation.” 

Although final EPA action on this proposed redesignation will 

not occur until year 2014, we find that the Las Vegas Valley PM10

Maintenance Plan satisfies the requirement to provide for 

maintenance of the NAAQS for at least 10 years after 

redesignation, which in this case, means through 2024, because 

(1) significant emissions controls (e.g. Clark County’s fugitive 

dust regulations) remain in place and will continue to provide 

reductions that keep the area in attainment; (2) the 2023 

projected emission inventory is well below the 2008 attainment 

year level and is expected to decline or remain stable during 

the 2023 to 2024 period due to continued developed of lands 

within the BLM disposal area and corresponding reduction in wind 

erosion over vacant disturbed land; and (3) air quality 

concentrations are well below the 24-hour PM10 NAAQS, and, when 

coupled with the emission inventory projections through 2023, 

clearly show it would be very unlikely for a PM10 violation to 

occur in 2024. 

For the above reasons, EPA believes that the area will 

continue to maintain the 24-hour PM10 NAAQS at least through 2024 

and that the Las Vegas Valley PM10 Maintenance Plan provides for 

maintenance for a period of ten years following redesignation. 

Thus, if EPA finalizes its proposed approval of the Las Vegas 

Valley PM10 Maintenance Plan in 2014, it is based on a showing, 
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in accordance with section 175A, that the Las Vegas Valley PM10

Maintenance Plan provides for maintenance for at least ten years 

after redesignation. 

3. Monitoring Network 

Continued ambient monitoring of an area is generally 

required over the maintenance period. As discussed in section 

V.A. of this document, PM10 is currently monitored by Clark 

County DAQ within the Las Vegas Valley PM10 nonattainment area. 

In the Las Vegas Valley PM10 Maintenance Plan (see section 6-8 of 

the plan), Clark County commits to continue operation of an air 

quality monitoring network that meets or exceeds the minimum 

monitoring requirements and will be relying on ambient PM10

monitoring to verify continued attainment of the 24-hour PM10

NAAQS. The Las Vegas Valley PM10 Maintenance Plan also notes that 

a review of the entire monitoring network will be undertaken 

annually as required by federal regulations.30 We find Clark 

County’s commitment for continued ambient PM10 monitoring as set 

forth in the Las Vegas Valley PM10 Maintenance Plan to be 

acceptable. 

4. Verification of Continued Attainment 

Clark County has the legal authority to implement and 

enforce the requirements in the Las Vegas Valley PM10 Maintenance 

 

30 EPA’s requirements for annual review of monitoring networks are found at 

40 CFR 58.10. 
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Plan. This includes the authority to adopt, implement and 

enforce any emission control contingency measures determined to 

be necessary to correct 24-hour PM10 NAAQS violations. To verify 

continued attainment, Clark County commits in the PM10

Maintenance Plan to the continued operation of a PM10 monitoring 

network that meets EPA ambient air quality surveillance 

requirements. 

Second, the transportation conformity process, which would 

require a comparison of on-road motor vehicle emissions that 

would occur under new or amended regional transportation plans 

and programs with the MVEBs in the Las Vegas Valley PM10

Maintenance Plan, represents another means by which to verify 

continued attainment of the 24-hour PM10 NAAQS in the Las Vegas 

Valley. Lastly, while not cited in the plan, Clark County must 

inventory emissions sources and report to EPA on a periodic 

basis under 40 CFR part 51, subpart A (“Air Emissions Reporting 

Requirements”). These emissions inventory updates will provide a 

third way to evaluate emissions trends in the area and thereby 

verify continued attainment of the NAAQS. These methods are 

sufficient for the purpose of verifying continued attainment. 

5. Contingency Provisions 

CAA section 175A(d) requires that maintenance plans include 

contingency provisions, as EPA deems necessary, to promptly 

correct any violations of the NAAQS that occur after 
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redesignation of the area. Such provisions must include a 

requirement that the State will implement all measures with 

respect to the control of the air pollutant concerned that were 

contained in the SIP for the area before redesignation of the 

area as an attainment area. In this instance, the Las Vegas 

Valley PM10 Maintenance Plan does not provide for the repeal or 

relaxation of any of the measures that contributed to attainment 

of the PM10 standard in Las Vegas Valley, and thus, the plan need 

not provide for any such measures to be reinstituted as a 

contingency in the event of an exceedance of the NAAQS. 

Contingency provisions for maintenance plan purposes are 

distinguished from those generally required for nonattainment 

areas under section 172(c)(9) in that they are not required to 

be fully-adopted measures that will take effect without further 

action by the state in order for the maintenance plan to be 

approved. However, the contingency plan is considered to be an 

enforceable part of the SIP and should ensure that the 

contingency measures are adopted expeditiously once they are 

triggered by a specified event. The maintenance plan should 

clearly identify the measures to be adopted, a schedule and 

procedure for adoption and implementation, and a specific 

timeline for action by the State. As a necessary part of the 

plan, the State should also identify specific indicators or 
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triggers, which will be used to determine when the contingency 

measures need to be implemented. 

As required by section 175A of the CAA, Clark County has 

adopted a contingency plan to address possible future PM10 air 

quality problems. See section 6.9 of the Las Vegas Valley PM10

Maintenance Plan. As described in section 6.9 of the maintenance 

plan, Clark County DAQ intends to rely on its continuous ambient 

PM10 monitoring network to track PM10 concentrations and has 

selected a confirmed violation of the PM10 NAAQS, defined as more 

than one expected exceedance per year averaged over a three-year 

period, as the primary triggering mechanism. Clark County DAQ 

refers to the date sixty days from such a violation as the 

trigger date after which the contingency plan would go into 

effect. 

Under the contingency plan, within 45 days of the trigger 

date, Clark County DAQ would notify EPA that an internal review 

process has begun to evaluate potential contingency measures. 

The list of potential contingency measures, not intended to be 

inclusive, includes: 

(1) Implementing a new dust control permit requirement for 

short-term activities that disturb or have the potential to 

disturb soils that emit PM10, such as mechanized weed abatement, 

fair, carnivals, Christmas tree and Halloween pumpkin lots, art 

sales; 
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(2) Conducting a comprehensive review and update of Clark 

County’s Construction Activities Dust Control Handbook to 

increase the effectiveness of existing Best Management Practices 

(BMPs) and to identify new BMPs. Examples include: new 

management practices for soil-disturbing activities and 

practices for roadway and detention basin maintenance 

activities; 

(3) Reviewing dust mitigation plan requirements in Clark 

County Rule 90 and 92, focusing on reducing acreage-trigger 

thresholds, incorporating additional mitigation plan criteria 

and lowering applicability thresholds for unpaved parking lots; 

(4) Reassigning staff to provide additional field 

enforcement of the air quality regulations that control sources 

of fugitive dust emissions; 

(5) Mapping construction activities during inspections to 

collect PM10 data to provide greater accuracy for calculating 

emissions from these activities; 

(6) Developing a new dust control database to strengthen 

oversight of dust control permits and improve compliance; and 

(7) Amending fugitive dust regulations to incorporate new 

technologies and measure for controlling emissions and prevent 

them from crossing property lines or causing a nuisance. 

Within 90 days of the notification to EPA, Clark County DAQ 

has committed to send EPA an informational report outlining 
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recommended actions. Clark County DAQ will then solicit public 

involvement and Clark County Board of Commissioners and/or the 

State Environmental Commission will hold public hearings, as 

necessary, to consider recommended contingency measures. Under 

the contingency plan, the selected contingency measures must be 

adopted and implemented within 18 months of the submittal of the 

informational report to EPA. 

Based on our understanding of the contingency plan, as 

summarized above, we find that the contingency provisions of the 

Las Vegas Valley PM10 Maintenance Plan clearly identify specific 

contingency measures, contain tracking and triggering mechanisms 

to determine when contingency measures are needed, contain a 

description of the process of recommending and implementing 

contingency measures, and contain specific timelines for action. 

Thus, we conclude that the contingency provisions of the Las 

Vegas Valley PM10 Maintenance Plan are adequate to ensure prompt 

correction of a violation and therefore comply with section 

175A(d) of the Act. 

6. Subsequent Maintenance Plan Revisions 

CAA section 175A(b) provides that States shall submit a SIP 

revision 8 years after redesignation providing for maintaining 

the NAAQS for an additional 10 years. The Las Vegas Valley PM10

Maintenance Plan includes a commitment to prepare and submit a 

revised maintenance plan eight years after redesignation to 
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attainment. See section 6.10 of the Las Vegas Valley PM10

Maintenance Plan. 

7. Motor Vehicle Emissions Budgets 

Transportation conformity is required by section 176(c) of 

the CAA. Our transportation conformity rule (codified in 40 CFR 

part 93, subpart A) requires that transportation plans, 

programs, and projects conform to SIPs and establishes the 

criteria and procedures for determining whether or not they do 

so. Conformity to the SIP means that transportation activities 

will not produce new air quality violations, worsen existing 

violations, or delay timely attainment of the national ambient 

air quality standards. 

PM10 maintenance plan submittals must specify the maximum 

emissions of transportation-related PM10 emissions31 allowed in 

the last year of the maintenance period, i.e., the motor vehicle 

emissions budgets (MVEBs). (MVEBs may also be specified for 

additional years during the maintenance period.) The MVEBs serve 

as a ceiling on emissions that would result from an area's 

 

31 Transportation-related emissions of volatile organic compounds (VOC) 

and/or oxides of nitrogen (NOx) emissions must also be specified in PM10 areas 

if EPA or the state finds that transportation-related emissions of one or 

both of these precursors within the nonattainment area are a significant 

contributor to the PM10 nonattainment problem and has so notified the 

metropolitan planning organization (MPO) and the U.S. Department of 

Transportation (DOT), or if the applicable SIP revision or SIP revision 

submittal establishes an approved or adequate budget for such emissions as 

part of the RFP, attainment or maintenance strategy. 40 CFR 93.102(2)(iii). 

Neither of these conditions apply to the Las Vegas Valley PM10 nonattainment 

area, and thus, the Las Vegas Valley PM10 Maintenance Plan establishes MVEBs 

only for PM10, not for PM10 precursors. 
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planned transportation system. The MVEB concept is further 

explained in the preamble to the November 24, 1993, 

transportation conformity rule (58 FR 62188). The preamble 

describes how to establish MVEBs in the SIP and how to revise 

the MVEBs if needed. 

The maintenance plan submittal must demonstrate that these 

emissions levels, when considered with emissions from all other 

sources, are consistent with maintenance of the NAAQS. In order 

for us to find these emissions levels or “budgets” adequate and 

approvable, the submittal must meet the conformity adequacy 

provisions of 40 CFR 93.118(e)(4) and (5). For more information 

on the transportation conformity requirement and applicable 

policies on MVEBs, please visit our transportation conformity 

Web site at: 

http://www.epa.gov/otaq/stateresources/transconf/index.htm. 

EPA’s process for determining adequacy of a MVEB consists 

of three basic steps: (1) notifying the public of a SIP 

submission; (2) providing the public the opportunity to comment 

on the MVEB during a public comment period; and, (3) making a 

finding of adequacy or inadequacy. The process for determining 

the adequacy of a submitted MVEB is codified at 40 CFR 

93.118(f). 

On November 7, 2012, EPA announced the availability of the 

Las Vegas Valley PM10 Maintenance Plan with MVEBs and a 30-day 
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public comment period on EPA's Adequacy Web site at: 

http://www.epa.gov/otaq/stateresources/transconf/currsips.htm

The comment period for this notification ended on December 7, 

2012, and EPA received no comments from the public. Note, 

however, that a second mechanism is also provided for EPA review 

and public comment on MVEBs, as described in 40 CFR 

93.118(f)(2). This mechanism provides for EPA’s review of the 

adequacy of an implementation plan MVEB simultaneously with its 

review and approval and/or disapproval of the applicable SIP 

revision itself. In this action, EPA used the web notification 

discussed above to solicit public comments on the adequacy of 

Clark County’s MVEBs, but is taking comment on the approvability 

of the submitted MVEBs through this proposed rule. 

The Las Vegas Valley PM10 Maintenance Plan contains designday PM10 MVEBs for the BLM disposal area portion of the Las Vegas 

Valley PM10 nonattainment area for the last year of the 

maintenance period (2023), as well as the 2008 base year 

(attainment inventory) and an interim year (2015). Table 3 

presents the MVEBs from the Las Vegas Valley PM10 Maintenance 

Plan and shows how they are derived. Specifically, the MVEBs 

represent the sum of certain source categories or subcategories 

from the emissions inventories prepare for the Las Vegas Valley 

PM10 Maintenance Plan plus a safety margin. The applicable source 

categories or subcategories included in the MVEBs include 
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vehicle emissions (including exhaust, brake wear, and tire 

wear), paved road dust, unpaved road dust, and three 

construction-related source subcategories (road construction 

dust, construction track-out, and wind erosion associated with 

road construction). The safety margins represent the difference 

between the sum of the emissions from the source categories or 

subcategories described above and the PM10 MVEB currently in 

effect in Las Vegas Valley under the approved Las Vegas Valley 

PM10 Attainment Plan (i.e., 141.41 tons per day). 

TABLE 3: MOTOR VEHICLE EMISSIONS BUDGETS IN THE LAS VEGAS VALLEY 

PM10 MAINTENANCE PLAN 

Design-Day Emissions (PM10, 

tons per day)a 

Category 2008 2015 2023 

Vehicle (exhaust, brake wear, 

and tire wear) 3.08 2.52 2.75

Paved Road Dust 30.85 38.04 48.78

Unpaved Road Dust (public) 0.28 0.32 0.36

Road Construction Dust 1.54 1.87 2.05

Construction Track-Out 0.25 0.30 0.33

Wind Erosion (road construction) 6.53 7.73 8.85

Subtotals 42.53 50.78 63.12

Safety Margin 98.88 90.63 78.29

Totals 141.41 141.41 141.41

a Corresponds to the BLM disposal area portion of Las Vegas 

Valley. 

SOURCE: Derived from tables 7-1, 7-2, and 7-3 in section 7.0 

in the Las Vegas Valley PM10 Maintenance Plan. 

The MVEBs in the Las Vegas Valley PM10 Maintenance Plan 

reflect: (1) on-road motor vehicle emission factors from EPA’s 
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current motor vehicle emissions factor model (MOVES); (2) 

fugitive paved and unpaved road and road construction emission 

factors from Compilation of Air Pollutant Emission Factors (AP42);32 and (3) updated vehicle activity data from the Regional 

Transportation Commission of Southern Nevada’s (RTC’s) Clark 

County Activity-Based Travel Demand Simulation Model (TransCAD) 

transportation modeling system. 

As described above, the Las Vegas Valley PM10 Maintenance 

plan uses a 2008 attainment-year emissions inventory to project 

emissions to 2015 and 2023 and show continually decreasing 

emissions, thereby demonstrating maintenance of the NAAQS 

through 2023. As shown in table 2 of this document, the Las 

Vegas Valley PM10 Maintenance Plan estimates that design-day 

emissions in the BLM disposal area portion of the Las Vegas PM10

nonattainment area will decrease from approximately 710 tons per 

day in 2008 to approximately 600 tons per day in 2015 and will 

then further decrease to approximately 490 tons per day in 2023. 

A state may choose to apply a safety margin under our 

transportation conformity rule so long as such margins are 

 

32 AP-42, Compilation of Air Pollutant Emission Factors, is the primary 

compilation of EPA's emission factor information. It contains emission 

factors and process information for more than 200 air pollution source 

categories, including paved roads. EPA released an update to AP-42 in January 

of 2011, which revised the equation for estimating paved road dust emissions 

based on an updated regression that included new emission tests results. 

Clark County DAQ used the updated AP-42 equation with local data on vehicle 

weight and silt loading data collected in 2003-2006 with Vehicle Miles 

Traveled (VMT) data from RTC’s TransCAD model to estimate paved road 

emissions. 
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explicitly quantified in the applicable plan and are shown to be 

consistent with attainment or maintenance of the NAAQS 

(whichever is relevant to the particular plan). See 40 CFR 

93.124(a). For the Las Vegas Valley PM10 Maintenance Plan, Clark 

County DAQ increased the motor vehicle related emissions 

estimates (i.e., vehicle, paved and unpaved road dust, 

construction track-out, and road construction (including related 

wind erosion) to equal 141.41 tons per day, which is the 2006 

attainment-year MVEB approved in connection with the Las Vegas 

Valley PM10 Attainment Plan. The Las Vegas Valley PM10 Maintenance 

Plan demonstrates continued maintenance with the additional 

safety margins by showing that, with the safety margins added to 

the estimates for 2015 and 2023, the overall emissions in 2015 

(694.35 tons per day) and 2023 (563.53 tons per day) would still 

be less than the emissions inventory for the attainment year 

2008 (706.55 tons per day). See table 7-3 of the Las Vegas 

Valley PM10 Maintenance Plan. 

EPA is proposing to approve the MVEBs for 2008, 2015 and 

2023, shown in table 3 above, as part of our approval of Las 

Vegas Valley PM10 Maintenance Plan. EPA has determined that the 

MVEB emission targets are consistent with emission control 

measures in the SIP and are consistent with maintenance of the 

24-hour PM10 standard in Las Vegas Valley through 2023. The 

details of EPA’s evaluation of the MVEBs for compliance with the 
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budget adequacy criteria of 40 CFR 93.118(e) are provided in a 

separate memorandum33 included in the docket of this rulemaking. 

Because the budgets EPA approved in 2004 are the same level as 

the budgets EPA is proposing to approve in this action, if EPA 

approves the MVEBs in the final rulemaking action, it would not 

change the budgets currently in use for transportation 

conformity determinations for Clark County. Any and all comments 

on the approvability of the MVEBs should be submitted during the 

comment period stated in the DATES section of this document. 

VI. Evaluation of Revisions to Clark County Fugitive Dust Rules 

As noted above, the Las Vegas Valley PM10 Maintenance Plan 

relies on the continued application of the county’s fugitive 

dust rules, particularly sections 90 through 94; however, these 

rules, with the exception of section 94, as approved into the 

SIP, apply within the “PM10 nonattainment area (hydrographic 

basin 212).” Section 94 applies county-wide, not just in the PM10 

nonattainment area. Redesignation of the Las Vegas Valley PM10

nonattainment area to attainment, as proposed herein, could 

undermine continued applicability and enforceability of the 

rules. To address this issue, the Clark County Board of County 

Commissioners recently adopted revisions to the rules to clarify 

 

33 See EPA memorandum dated October 28, 2013 titled, “Adequacy Documentation 

for Plan Motor Vehicle Emission Budgets in August 2012 Clark County PM10

Maintenance State Implementation Plan.” 
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their continued applicability within both a “PM10 nonattainment 

area” and an “area subject to a PM10 maintenance plan.” 

Clark County section 90 specifies requirements and measures 

to be implemented within the nonattainment area (and Apex 

Valley) for control of fugitive dust emissions from open areas 

and vacant lots. Section 91 specifies requirements and measures 

to be implemented within the nonattainment area (and Apex 

Valley) for control of fugitive dust from unpaved roads, unpaved 

alleys, and unpaved easement roads. Section 92 specifies 

requirements and measures to be implemented within the 

nonattainment area (and Apex Valley) for control of fugitive 

dust from unpaved parking lots, material handling and storage 

yards, and vehicle and equipment storage yards, not otherwise 

regulated under Clark County section 94 (“Permitting & Dust 

Control for Construction Activities”). Section 93 specifies 

requirements and measures to be implemented within the 

nonattainment area (and Apex Valley) for control of fugitive 

dust from paved roads and street sweeping equipment. 

EPA most recently approved section 90 at 71 FR 63250 

(October 30, 2006); section 91 at 69 FR 32272 (June 9, 2004), 

section 92 at 71 FR 63250 (October 30, 2006); and section 93 at 

71 FR 63250 (October 30, 2006). Relative to the existing SIP 

versions, as discussed above, the rules have been amended to 

ensure that the rules continue to apply once the area is 
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redesignated to attainment for PM10. The rules have also been 

amended to reflect changes in the name of the county’s air 

pollution control district and to use the term “hydrographic 

area” instead of “hydrographic basin.” Lastly, Clark County has 

amended section 92 to add an exemption from the paving 

requirement for new equestrian staging areas so long as the 

applicable performance standards in the rule are met. We find 

that these changes generally improve the SIP as well as 

providing the necessary support for the Las Vegas PM10

Maintenance Plan. Moreover, we find that the limited and 

qualified exemption from the paving requirement under Clark 

County section 92 for new equestrian staging areas would have no 

effect on continued maintenance of the PM10 standard in Las Vegas 

Valley and is acceptable. 

NDEP’s May 27, 2014 SIP revision submittal of amended Clark 

County fugitive dust rules also includes an amended version of 

section 41 (“Fugitive dust”). The most recent approval by EPA of 

Clark County section 41 was at 46 FR 43141 (August 27, 1981). 

This older fugitive dust rule establishes general fugitive dust 

requirements and measures applicable throughout Clark County but 

that are largely superseded with respect to construction 

activities by section 94 and, within the PM10 nonattainment area 

(and Apex Valley), by the specific measures and other 

requirements in sections 90 through 93. Section 41 also contains 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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certain provisions related to off-road vehicle and motocross 

racing that apply only within the nonattainment area. The recent 

amendments adopted by the Clark County Board of County 

Commissioners ensure the continued applicability of the off-road 

vehicle and motocross-related provisions once the area is 

redesignated to attainment. Other changes relative to the SIP 

version include the deletion of provisions addressing vacant 

lots from which topsoil was removed prior to 1973 and the 

addition of provisions intended to clarify the conditions that 

the rule seeks to avoid through application of “reasonable 

precautions.” Within Las Vegas Valley and Apex Valley, vacant 

lots are now addressed by the specific measures and other 

requirements in Clark County section 90. The other changes in 

section 41 generally improve the SIP as well as provide support 

for the Las Vegas Valley PM10 Maintenance Plan.34 

Therefore, for the reasons discussed above, we find that 

Clark County fugitive dust rules sections 90 through 93, and 41, 

as amended by the Clark County Board of County Commissioners on 

April 15, 2014 (effective April 29, 2014) and submitted by NDEP 

on May 27, 2014, would not interfere with attainment or 

maintenance of any of the NAAQS and would provide necessary 

 

34 As amended on April 15, 2014, section 41 (see subsection 41.2.3) continues 

to include outdated references to Clark County section 15, which was replaced 

by section 12 a number of years ago. We recommend that Clark County update 

section 41 with the correct references to the appropriate subsections of 

section 12. 
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support for the Las Vegas Valley PM10 Maintenance Plan, and thus 

are approvable under CAA section 110(l).35 As such, we propose to 

approve the amended Clark County fugitive dust rules as a 

revision to the Nevada SIP. 

VII. Proposed Deletion of TSP Designation for Las Vegas Valley 

A. General Considerations 

Consistent with section 107(d)(4)(B), we have considered 

the continued necessity for retaining the remaining TSP area 

designations in Nevada, and as discussed below, we have decided 

that the TSP nonattainment designation for Las Vegas Valley (HA 

#212) is no longer necessary. As a result, we are proposing to 

delete it from the TSP table in 40 CFR 81.329. 

To evaluate whether the TSP area designation should be 

retained or can be deleted, we have relied upon the final rule 

implementing the PM10 NAAQS (see 52 FR 24634, July 1, 1987), a 

policy memorandum on TSP redesignations (see memo dated May 20, 

1992 from Joseph W. Paisie, Acting Chief, SO2/Particulate Matter 

Programs Branch, EPA Office of Air Quality Planning and 

Standards, to Chief, Air Branch, Regions I-X, entitled “TSP 

Redesignation Request”), and our proposed and final rules 

establishing maximum allowable increases in concentrations (also 

 

35 CAA section 110(l) provides, in relevant part, that EPA shall not approve 

a SIP revision if the SIP revision would interfere with any applicable 

requirement concerning attainment and reasonable further progress, or any 

other applicable requirement of the CAA. 
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known as “increments”) for PM10 (see the proposed rule at 54 FR 

41218, October 5, 1989, and the final rule at 58 FR 31622, June 

3, 1993). 

Based on the above references, we believe that the relevant 

considerations for evaluating whether the necessity of retaining 

the TSP area designations depend upon the status of a given area 

with respect to TSP and PM10. For areas that are nonattainment 

for TSP but attainment for PM10, we generally find that the TSP 

designations are no longer necessary and can be deleted when EPA 

(1) approves a State’s revised PSD program containing the PM10

increments, (2) promulgates the PM10 increments into a State’s 

SIP where the State chooses not to adopt the increments on their 

own, or (3) approves a State’s request for delegation of PSD 

responsibility under 40 CFR section 52.21(u). See 58 FR 31622, 

at 31635 (June 3, 1993). 

For areas that are nonattainment for TSP and nonattainment 

for PM10, an additional consideration is whether deletion of the 

TSP designations would automatically relax any emissions 

limitations, control measures or programs approved into the SIP. 

If such a relaxation would occur automatically with deletion of 

the TSP area designations, then we will not delete the 

designations until we are satisfied that the resulting SIP 

relaxation would not interfere with any applicable requirement 

concerning attainment, reasonable further progress (RFP), or 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

78 

maintenance of the NAAQS or any other requirement of the Clean 

Air Act in the affected areas. See section 110(l) of the Act. 

In the case of Las Vegas Valley, we believe that the 

considerations for both types of areas described above are 

relevant because although Las Vegas Valley is nonattainment for 

PM10, we are proposing to redesignate the area to attainment for 

PM10 in today’s action. Thus, we must take into account both the 

potential for relaxation that would be inconsistent with 

continued maintenance of the PM10 NAAQS as well as protection of 

the PM10 increments (as applies in areas designated attainment or 

unclassifiable). 

B. Deletion of TSP Nonattainment Area Designation for Las Vegas 

Valley 

With respect to protection of the PM10 increments, the TSP 

nonattainment designations are no longer necessary in Las Vegas 

Valley because we have approved Clark County’s NSR regulations 

as satisfying the related PSD requirements. See 69 FR 54006 

September 7, 2004.36 We recognize that NDEP retains jurisdiction 

over certain types of sources in Clark County but note that 

EPA’s PSD pre-construction permit program promulgated at 40 CFR 

 

36 More recently, EPA has taken limited approval and limited disapproval of 

amendments to Clark County’s NSR regulations. 77 FR 64039 (October 18, 2012). 

In our 2012 final rule, we identified a number of deficiencies in the Clark 

County’s NSR regulations, but none of these deficiencies relate directly to 

protection of the PM10 increments. 
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52.21 apply to those sources under a delegation agreement 

between NDEP and EPA. See 40 CFR 52.1485(b). 

To ensure that deletion of the TSP nonattainment 

designation for Las Vegas Valley would not result in any 

automatic relaxations in SIP emissions limitations, control 

measures or programs that would interfere with attainment, RFP 

or maintenance of the NAAQS (including PM10) or any other 

requirement of the Act, we reviewed the following portions of 

the Nevada SIP: 

· The TSP portions of the Las Vegas Valley Air Quality 

Implementation Plan (AQIP) adopted in response to the CAA, 

as amended in 1977; 

· State stationary source rules including NAC 445B.22017 

(“Visible emissions: Maximum opacity; determination and 

monitoring of opacity”) and NAC 445B.2203 (“Emissions of 

particulate matter: Fuel-burning equipment”); 

· Clark County stationary source rules, including section 26 

(“Emission of visible air contaminants”), section 27 

(“Particulate matter from process weight rate”), section 28 

(“Fuel burning equipment”), section 30 (“Incinerators”), 

and section 42 (“Open burning”); and 

· Clark County fugitive dust rules, including section 41 and 

sections 90 through 94, as proposed for approval herein 

(see section VI of this document). 
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Based on our review of the TSP provisions in the Las Vegas 

Valley AQIP and the various rules cited above, we find that none 

are contingent upon continuation of the TSP nonattainment 

designations, and thus deletion of the TSP designations would 

not automatically relax any standard. More specifically: 

· The Las Vegas Valley AQIP relies primarily on fugitive dust 

controls, which are now codified in section 41 and sections 

90 through 94, and for which applicability does not depend 

on TSP designations; 

· State stationary source rules that apply to coal-fired 

power plants (i.e., the sources that fall under State 

jurisdiction in Clark County) contain percent opacity 

limits and PM10 limits for which the TSP designation is 

irrelevant; 

· Clark County stationary source rules sections 26, 27, 28, 

30, and 42 do not contain requirements for which the TSP 

area designation is relevant; and 

· The applicability of the relevant portion of the Clark 

County rule section 41 (“Fugitive dust”) and the other 

county fugitive dust rules sections 90 through 94 are 

expressed in terms of the designated boundaries of the PM10

nonattainment area (or area subject to a PM10 maintenance 

plan), and not in terms of the boundaries of the TSP area. 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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In summary, because the PSD PM10 increments apply in Las 

Vegas Valley and because the deletion of the TSP nonattainment 

designation for Las Vegas Valley would not automatically relax 

any emissions limitation or control measure in the Nevada SIP, 

we find that the TSP nonattainment designation is no longer 

necessary and can be deleted. Based on the above discussion and 

evaluation, therefore, we are proposing to delete the TSP 

nonattainment area designation for Las Vegas Valley (HA #212) 

from the “Nevada-TSP” table in 40 CFR 81.329. 

VIII. Proposed Action and Request for Public Comment 

Under CAA section 110(k)(3), and for the reasons set forth 

above, the EPA is proposing to approve NDEP’s submittal dated 

September 7, 2012 of the Redesignation Request and Maintenance 

Plan for Particulate Matter (PM10), Clark County, Nevada (August 

2012) (“Las Vegas Valley PM10 Maintenance Plan”) as a revision to 

the Nevada SIP. The EPA finds that the maintenance demonstration 

showing how the area will continue to attain the 24-hour PM10

NAAQS for 10 years beyond redesignation, and the contingency 

provisions describing the actions that Clark County will take in 

the event of a future monitored violation, meet all applicable 

requirements for maintenance plans and related contingency 

provisions in CAA section 175A. The EPA is also proposing to 

approve the motor vehicle emissions budgets in the Las Vegas 

Valley PM10 Maintenance Plan (i.e., 141.14 tons per day in 2008, 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

82 

2015, and 2023) because we find they meet the applicable 

transportation conformity requirements under 40 CFR 93.118(e). 

Second, under CAA section 107(d)(3)(D), we are proposing to 

approve NDEP’s request, which accompanied the submittal of the 

maintenance plan, to redesignate the Las Vegas Valley PM10

nonattainment area to attainment for the 24-hour PM10 NAAQS. We 

are doing so based on our conclusion that the area has met the 

five criteria for redesignation under CAA section 107(d)(3)(E). 

Our conclusion in this regard is in turn based on our proposed 

determination that the area has attained the 24-hour PM10 NAAQS, 

that relevant portions of the Nevada SIP are fully approved, 

that the improvement in air quality is due to permanent and 

enforceable reductions in emissions, that Nevada has met all 

requirements applicable to the Las Vegas Valley PM10

nonattainment area with respect to section 110 and part D of the 

CAA, and based on our proposed approval as part of this action 

of the Las Vegas Valley PM10 Maintenance Plan. Our proposed 

determination that the area has attained the 24-hour PM10 NAAQS 

is based in part on our concurrence with Clark County DAQ that 

the exceedances monitored in Las Vegas Valley on July 3, 2011 

were caused by a high wind exceptional event and our related 

exclusion of the exceedances from the attainment determination. 

Third, EPA is proposing to approve revisions to Clark 

County fugitive dust rules sections 41, and 90 through 93 that 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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were submitted on May 27, 2014 as a revision to the Nevada SIP 

because we find that they ensure continued implementation of the 

rules after redesignation of Las Vegas Valley to attainment and 

because they meet all other applicable requirements. Proposing 

to do so is consistent with the assumptions upon which the 

maintenance plan is based. 

Lastly, EPA is proposing to delete the area designation for 

Las Vegas Valley for the revoked national standard for total 

suspended particulate because the designation is no longer 

necessary. 

EPA is soliciting public comments on the issues discussed 

in this document or on other relevant matters. We will accept 

comments from the public on this proposal for the next 30 days. 

We will consider these comments before taking final action. 

IX. Statutory and Executive Order Reviews 

Under the CAA, redesignation of an area to attainment and 

the accompanying approval of a maintenance plan under section 

107(d)(3)(E) are actions that affect the status of a 

geographical area and do not impose any additional regulatory 

requirements on sources beyond those imposed by State law. 

Redesignation to attainment does not in and of itself create any 

new requirements, but rather results in the applicability of 

requirements contained in the CAA for areas that have been 

redesignated to attainment. Moreover, the Administrator is 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

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required to approve a SIP submission that complies with the 

provisions of the Act and applicable Federal regulations. 42 

U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP 

submissions, EPA’s role is to approve State choices, provided 

that they meet the criteria of the Clean Air Act. Accordingly, 

these actions merely propose to approve a State plan and 

redesignation request as meeting Federal requirements and do not 

impose additional requirements beyond those by State law. For 

these reasons, these proposed actions: 

· Are not a “significant regulatory action” subject to review 

by the Office of Management and Budget under Executive 

Order 12866 (58 FR 51735, October 4, 1993) and Executive 

Order 13563 (76 FR 3821, January 21, 2011); 

· Do not impose an information collection burden under the 

provisions of the Paperwork Reduction Act (44 U.S.C. 3501 

et seq.); 

· Are certified as not having a significant economic impact 

on a substantial number of small entities under the 

Regulatory Flexibility Act (5 U.S.C. 601 et seq.); 

· Do not contain any unfunded mandate or significantly or 

uniquely affect small governments, as described in the 

Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4); 

· Do not have Federalism implications as specified in 
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2014. We have taken steps to ensure the accuracy of this version, but it is not the official version. 

85 

Executive Order 13132 (64 FR 43255, August 10, 1999); 

· Are not an economically significant regulatory action based 

on health or safety risks subject to Executive Order 13045 

(62 FR 19885, April 23, 1997); 

· Are not a significant regulatory action subject to 

Executive Order 13211 (66 FR 28355, May 22, 2001); 

· Are not subject to requirements of Section 12(d) of the 

National Technology Transfer and Advancement Act of 1995 

(15 U.S.C. 272 note) because application of those 

requirements would be inconsistent with the CAA; and 

· Do not provide EPA with the discretionary authority to 

address disproportionate human health or environmental 

effects with practical, appropriate, and legally 

permissible methods under Executive Order 12898 (59 FR 

7629, February 16, 1994). 

In addition, this proposed rule does not have Tribal 

implications as specified by Executive Order 13175 (65 FR 67249, 

November 9, 2000), because the SIP is not approved to apply in 

Indian country located in the State, and EPA notes that it will 

not impose substantial direct costs on Tribal governments or 

preempt Tribal law. Nonetheless, EPA has discussed the proposed 

action with the one Tribe, the Las Vegas Paiute Tribe, located 

within the Las Vegas Valley PM10 nonattainment area. 
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List of Subjects 

40 CFR Part 52 

Environmental protection, Air pollution control, 

Intergovernmental relations, Nitrogen dioxide, Particulate 

matter, Reporting and recordkeeping requirements, Sulfur 

dioxide. 

40 CFR Part 81 

Environmental protection, Air pollution control, National 

parks, Wilderness areas. 

__27 June 2014__________ ________/s/_____________ 

Dated: Alexis Strauss 

 Acting Regional Administrator, 

Region IX.