United States Environmental Protection Agency, Region IX

Air Division

Technical Support Document

for

EPA's Notice of Proposed Rulemaking

for revisions to the 

Nevada State Implementation Plan

Clark County Department of Air Quality & Environmental Management

New Source Review Permitting Program, 

Including Minor Source, NSR and PSD programs

Roger Kohn

Laura Yannayon

Jeanhee Hong

July 11, 2012

Table of Contents

Section Page

Introduction 1

Agency Name 1

NSR Program SIP Revision Submittals 1

Background 3

Rule Summaries 4

General Summary 4

Section 0 Definitions 5

Section 12.0 Applicability, General Requirements and Transition Procedures 5

Section 12.1 Permit Requirements for Minor Sources 5

Section 12.2 Permit Requirements for Major Sources in Attainment Areas 8

Section 12.3 Permit Requirements for Major Sources in Nonattainment Areas 8

Section 12.4 Authority to Construct Application and Permit Requirements for Part 70 Sources 8

Rule Evaluations 9

General Summary 9

Section 0 Definitions 9

Section 12.0 Applicability, General Requirements and Transition Procedures 11

Section 12.1 Permit Requirements for Minor Sources 11

Section 12.2 Permit Requirements for Major Sources in Attainment Areas 20

Section 12.3 Permit Requirements for Major Sources in Nonattainment Areas 30

Section 12.4 Authority to Construct Application and Permit Requirements for Part 70 Sources 41

Section 110(l) of the Act 46

Section 193 of the Act 50

Recommendations for Rule Revisions 51

EPA’s Proposed Action 53
1

Introduction

Part C of title I of the Clean Air Act (CAA or Act) contains the provisions for the Prevention of 

Significant Deterioration (PSD) of air quality in areas designated as “attainment” or 

“unclassifiable” for the national ambient air quality standards (NAAQS). Part D of title I of the Act 

contains the requirements for areas designated “nonattainment” for any of the NAAQS. Both parts 

C and D of the Act require pre-construction permit programs for certain new or modified 

stationary sources of pollutants. The requirements under part C, referred to as “PSD New Source 

Review” (or simply PSD) apply to certain new or modified sources that emit pollutants for which 

the area is designated as attainment or unclassifiable and certain other (non-criteria) pollutants 

subject to regulation under the CAA. The requirements under part D, referred to as 

“Nonattainment NSR,” (or simply NSR) apply to certain new or modified sources of 

nonattainment pollutants in nonattainment areas. Considered collectively, the pre-construction 

permit requirements related to PSD and Nonattainment NSR are commonly referred to simply as 

“NSR.” Both of these programs apply to “major stationary sources” and “major modifications” as 

those terms are defined in 40 CFR Part 51 Subpart I. In addition to regulations for new and 

modified major stationary sources under parts C and D of title I, the CAA requires each state to 

include in its SIP a program to provide for the regulation of the construction and modification of 

any stationary source within the areas covered by the plan as necessary to assure that the NAAQS 

are achieved. These general pre-construction requirements are commonly referred to as “minor 

NSR.” See 40 CFR 51.160-51.164.

Agency Name

The Department of Air Quality (DAQ or Clark) is the air pollution control district for Clark 

County, Nevada. This county department was previously named the Department of Air Quality 

and Environmental Management, but on March 6, 2012, the Clark County Board of County 

Commissioners approved the name change to the Department of Air Quality.

NSR Program SIP Revision Submittals

The new and revised rules that are the subject of this Technical Support Document (TSD) were 

adopted by Clark on November 3, 2009, May 18, 2010, and March 6, 2012 and submitted to EPA 

via the Nevada Division of Environmental Protection (NDEP) by letters dated February 11, 2010, 

September 1, 2010, and May 22, 2012, respectively. NDEP is the governor’s designee for 

submitting official revisions of the Nevada State Implementation Plan (SIP) to EPA. The rules 

(referred to as “Sections”) that NDEP has requested that EPA approve as revisions to the Clark 

County portion of the Nevada SIP are as follows:

1

 1 DAQ also included a permitting regulation called “Section 12.11 (General Permits For Minor Stationary Sources)” 

as part of its NSR SIP Submittal but we are not proposing action on this regulation at this time.
2

Section 

Number Section Title Submittal Date(s)

0 Definitions 3/17/06, 2/11/10, 9/01/10,

1/13/11 and 5/22/12

12.0 Applicability, General Requirements and 

Transition Procedures 2/11/10

12.1 Permit Requirements for Minor Sources 2/11/10

12.2 Permit Requirements for Major Sources in 

Attainment Areas

3/17/06, 9/01/10, 1/13/11 and 

5/22/12

12.3 Permit Requirements for Major Sources in 

Nonattainment Areas Emission Offsets 3/17/06, 9/1/10

12.4 Authority to Construct Application and Permit 

Requirements For Part 70 Sources 9/01/10

These submitted versions of Sections 12.0, 12.1, 12.2, 12.3, and 12.4, collectively, establish a 

program for reviewing and permitting new or modified stationary sources in Clark County.

2 This 

program relies upon certain definitions contained in submitted Section 0 as well as the definition of 

“ambient air quality standards” in SIP-approved Section 11. These SIP revision submittals are 

collectively referred to herein as the “NSR SIP submittal” or “submitted NSR rules.” Although we 

are proposing to act on only the most recently submitted version of each rule, which supersedes 

any previous submittals of that rule, we have reviewed materials provided with the previous 

submittals for informational purposes. 

Consistent with Clark’s stated intent to have the submitted NSR rules replace the existing SIP NSR 

program in its entirety3

, EPA’s approval of the submitted NSR rules would have the effect of 

entirely superseding, or rescinding our prior approval of, each of the rules in the current 

SIP-approved NSR program, with the exception of two regulations: Nevada Administrative Code 

(NAC) 445B-22083, which is implemented by the State Environmental Commission (SEC) rather 

than Clark, and Section 11, which establishes Clark’s “ambient air quality standards.” Both NAC 

445B-22083 and Section 11 remain in the applicable Nevada SIP and will not be affected by our 

proposed action. The SIP-approved rules that would be superseded or rescinded, consistent with 

Clark’s request, are as follows:

 2 Section 12.4 also contains requirements to address the CAA title V requirements for operating permit programs, but 

we are not evaluating the rule for title V purposes at this time. We will evaluate Section 12.4 for compliance with the 

requirements of title V of the Act and EPA’s implementing regulations in 40 CFR part 70 following receipt of an 

official part 70 program submittal from Clark County containing this rule.

3 See Chapter 1, page 1-3 in “Proposed Revision To The Clark County Part Of The Nevada State Implementation 

Plan: Major Source New Source Review Program Rule Adoptions And Revisions,” August 31, 2010 (hereinafter 

“Major NSR SIP Submittal”).
3

Section 

Number Section Title SIP Approval Dates

0 Definitions 9/7/04

1 Definitions (33 specific terms) 4/14/81 & 6/21/82

12 Preconstruction Review For New Or Modified Stationary Sources 9/7/04

16 Operating Permits 6/18/82

58 Emission Reduction Credits 9/7/04

59 Emission Offsets 9/7/04

Background

As explained above, the submitted NSR rules will, upon approval, entirely replace the SIP rules 

approved by EPA on September 7, 2004 (69 FR 54006, Sections 0, 12, 58, and 59), and June 18, 

1982 (47 FR 26386, Section 16), with the exception of NAC 445B-22083 and Section 11, both of 

which remain in the SIP and are not affected by this action. For additional background 

information, the reader can consult the cited Federal Register notices. The current SIP-approved 

NSR program in Section 12 – Preconstruction Review for New or Modified Stationary Sources 

and Section 16 – Operating Permits, contains requirements for both major and minor stationary 

sources, in attainment and nonattainment areas of the County. Section 0 and Section 1 contain 

definitions relating to new sources and modifications to existing sources of air pollution, and their 

regulation. Sections 58 and 59 contain requirements for the generation and use of emission 

reduction credits.

Under the Act, as amended in 1977, EPA promulgated area designations within each State for all 

“criteria air pollutants” (pollutants for which NAAQS had been established). See 43 FR 8962, 

9012-9013 (March 3, 1978). In the initial 1978 area designations, EPA designated all areas within 

Clark County, other than hydrographic area #212 (referred to herein as “Las Vegas Valley”), as 

attainment or unclassifiable for all criteria air pollutants (i.e., oxidant, carbon monoxide (CO), 

total suspended particulate (TSP), sulfur dioxide (SO2), and nitrogen dioxide (NO2)). EPA 

designated Las Vegas Valley as a nonattainment area for oxidant, CO, and TSP and as an 

attainment area for SO2 and NO2. Id. In 1979, EPA replaced the oxidant NAAQS with a NAAQS 

for ozone, but Las Vegas Valley retained its nonattainment designation upon transition to the new 

standard. In 1986, EPA redesignated Las Vegas Valley from nonattainment to attainment for the 

ozone NAAQS (see 51 FR 41788, November 19, 1986). In 1987, EPA revised the NAAQS for 

particulate matter (see 52 FR 24634), replacing TSP as the indicator for PM with a new indicator 

called PM10 that includes only those particles with an aerodynamic diameter less than or equal to a 

nominal 10 micrometers, but Las Vegas Valley retained its nonattainment designation upon 

transition to the new standard. 

The CAA was significantly amended again in 1990. These amendments required states with areas 

that remained nonattainment to develop new attainment plans and revisions to existing 

Nonattainment NSR regulations. Las Vegas Valley was one of the areas that had not attained all of 

the NAAQS, and in 1991, EPA reaffirmed the nonattainment designations for Las Vegas Valley 

for CO and PM10. See 56 FR 56694, 56797-56799 (November 6, 1991). Las Vegas Valley 

remained designated attainment or unclassifiable for all other criteria pollutants, and the rest of 
4

Clark County remained designated attainment or unclassifiable for all criteria pollutants. In 1997, 

EPA revised the NAAQS for ozone to replace the existing 1-hour ozone standard of 0.12 parts per 

million (ppm) with an 8-hour standard set of 0.08 ppm (see 62 FR 33856, July 18, 1997) and 

promulgated a new NAAQS for particulate matter with an aerodynamic diameter less than or equal 

to a nominal 2.5 micrometers (PM2.5) (see 62 FR 38652, July 18, 1997).4 In 2004, EPA designated 

certain portions of Clark County as nonattainment for the 1997 8-hour ozone NAAQS (69 FR 

23858, 23919, April 30, 2004), and in 2005, EPA designated the entire State of Nevada as 

unclassifiable/attainment for the 1997 PM2.5 NAAQS (see 70 FR 944, January 5, 2005). 40 CFR 

81.329. In 2010, EPA redesignated Las Vegas Valley to attainment for the CO NAAQS. See 75 FR 

59090 (September 27, 2010). In 2011, EPA designated the entire State of Nevada as 

unclassifiable/attainment for the 2008 Lead (Pb) NAAQS. See 76 FR 72095 (November 22, 2011). 

In 2012, EPA designated the entire State of Nevada as unclassifiable/attainment for the 2008 

8-hour ozone NAAQS. See 77 FR 30088, 30134 (May 21, 2012).

Thus, Clark County is currently designated as attainment or unclassifiable for all NAAQS 

pollutants, with two exceptions: certain portions of Clark County are designated nonattainment for 

the 1997 8-hour ozone NAAQS, and the Las Vegas Valley area within Clark County is designated 

and classified as “serious” nonattainment for the PM10 NAAQS. 40 CFR 81.329. EPA has 

determined, however, that both of these nonattainment areas are attaining the standards. See 75 FR 

45485 (August 3, 2010) (Determination of Attainment for PM10 for the Las Vegas Valley 

Nonattainment Area, NV) and 76 FR 17343 (March 29, 2011) (Determination of Attainment for 

the Clark County 8-Hour Ozone Nonattainment Area Thus, although both of these areas remain 

designated “nonattainment” for these pollutants until such time as EPA redesignates them to 

“attainment” consistent with the requirements of CAA section 107(d)(3)(E), because of these 

determinations of attainment, the State of Nevada’s obligations under the CAA to submit 

attainment demonstrations and other planning requirements related to attainment of these NAAQS 

are suspended for so long as the areas continue to attain both NAAQS. See id. EPA last approved 

revisions to Clark County’s SIP-approved PSD, Nonattainment NSR, and minor NSR permit 

programs on September 7, 2004. 69 FR 54006.

Rule Summaries

General Summary

Submitted Sections 0, 12.0, 12.1, 12.2, 12.3, and 12.4 represent a comprehensive revision to Clark 

County's stationary source permitting programs and are intended to satisfy the requirements of

section 110(a)(2)(C) and parts C and D of title I of the Act. Section 0 contains definitions of terms 

relating to new sources and modifications to existing sources of air pollution, and their regulation. 

Section 0 also contains numerous definitions used in prohibitory local rules not directly related to 

NSR. With respect to Section 0, our proposed action applies to the entire submitted rule, not just 

those definitions directly related to NSR. Section 12.0 defines how the transition from the current 

SIP rules to the newly adopted rules will occur and also identifies general requirements for sources 

 4 EPA has also established increments for PM2.5 and established a July 20, 2012 deadline for states to submit PSD SIP 

revisions that incorporate these PM2.5 increments or alternative measures providing an equivalent level of protection.

See 75 FR 64864 (October 20, 2010).
5

that may be exempt from permit requirements. Section 12.1 contains the requirements for Clark to 

issue federally enforceable permits to “minor sources” as defined in Section 12.1.1(c). Sections 

12.2 and 12.3 contain the requirements for Clark to issue federally enforceable permits to major 

sources in attainment areas (12.2) and nonattainment areas (12.3) within Clark County. These 

requirements include those related to applicability, control standards (i.e, Lowest Achievable 

Emission Rate, or LAER) and emission offsets in nonattainment areas, and control standards (i.e., 

Best Available Control Technology, or BACT) and air quality impact analyses in attainment areas.

Sections 12.2 and 12.3 also contain procedural requirements for permit issuance. Section 12.4 

contains additional procedural requirements for permit issuance, including application and permit 

content requirements for stationary sources subject to title V of the CAA (federal operating 

permits). 

We provide more detailed evaluations of each of these rules in the “Rule Evaluations” section of

this Technical Support Document (TSD).

Section 0 – Definitions

This existing rule was significantly revised by the Clark County Board of County Commissioners’ 

rulemaking action of November 3, 2009 and most recently revised on March 6, 2012. Section 0 

consists of definitions for terms relating to new sources and modifications to existing sources of air 

pollution. Section 0 also contains numerous definitions used in prohibitory local rules not directly

related to new source review. Some of these prohibitory rules are already approved into the SIP. 

The revisions eliminated terms that are no longer used, updated terms to reflect their current 

meanings and added terms that support new rules and rule revisions. 

The definitions in Section 0 generally apply to multiple regulations, while the definitions provided

in each Section 12 rule only apply to that particular rule or to the specified subsection of that rule. 

Clark has relocated several definitions that are only used in a specific rule, such as Section 12.2 or 

Section 12.3, to those specific rules. Terms that are not defined in a Section 12 rule generally have 

the meaning provided in Section 0, except as noted otherwise.

Section 12.0 – Applicability, General Requirements and Transition Procedures

This is a new rule that generally explains the applicability of the permitting rules to major and 

minor stationary sources (Sections 12.1-12.4 and 12.11), and is designed to help a reader quickly 

understand which part(s) of Section 12 may apply to a particular facility. Section 12.0 also

explains how the transition from the current SIP rules to the new rules will occur and identifies 

general requirements applicable to sources that may be exempt from permit requirements. 

Section 12.1 – Permit Requirements for Minor Sources

This is a new rule intended to implement Clark’s minor source permit program, as required by 40 

CFR sections 51.160 – 51.164. This program applies, with limited exceptions, to any existing, new 

or modified stationary source that has a “potential to emit” any of the following seven pollutants 

above certain “de minimis” levels but is not a “major stationary source” or “major modification” as 

defined in 40 CFR sections 51.165 or 51.166: PM10, CO, VOC, NOx, SO2, Pb, or H2S. 
6

Section 12.1 establishes specific application and permit requirements for all existing, new and 

modified minor sources. The rule includes sections for applicability, definitions, exemptions, and 

permit application and permit content requirements, as well as permit processing requirements 

applicable to Clark, including public notice requirements. Each rule section is discussed in further 

detail below. EPA notes that Clark has chosen to include many Title V permit related provisions in 

its new minor source program. Although most minor sources are not subject to the CAA’s Title V 

operating permits program, we expect that many of the Title V-derived provisions in Clark’s minor 

NSR program will clarify its requirements and strengthen its enforceability.

Subsection 12.1.0 (Applicability), states that the rule applies to any stationary source with a 

potential to emit (PTE) a regulated air pollutant equal to or greater than the de minimis PTE 

thresholds specified in subsection 12.1.1(c) for minor sources, but less than the major source 

thresholds specified in Section 12.2, “Permit Requirements For Major Sources in Attainment 

Areas (Prevention Of Significant Deterioration),” and Section 12.3, “Permit Requirements For 

Major Sources in Nonattainment Areas (New Source Review).”

Subsection 12.1.1 (Definitions), defines seven specific terms used in Sections 12.0, 12.1, 12.4, 

12.5, and 12.11, and explains how any terms not defined within these rules should be defined. 

Subsection 12.1.2 (Emission Units and Activities Exempt from Permit Requirements), provides a 

list (in paragraph (c)) of equipment and activities that are exempt from the permitting requirement 

of Section 12.1, and uses a cross-reference (in paragraph (a)) to exempt emission units deemed 

insignificant under Section 12.5 (Part 70 Operating Permit Requirements). This subsection also 

provides that such exempt equipment or activities must be listed in the application and permit, that 

such equipment or activities remain subject to other applicable requirements, and that the potential 

to emit of such exempt units or activities shall be considered when determining the PTE of a 

stationary source.

Paragraph (c) of subsection 12.1.2 exempts specific types of emission units and activities from the 

permitting requirements of Section 12.1 – for example, laboratory equipment used for specific 

purposes, hot water production not used for any industrial process, road maintenance activities, 

and several types of temporary construction activities, such as padding machines, debris grinders 

and trenching machines if being used under the conditions of a Dust Control Permit issued 

pursuant to Section 94. It also exempts temporary operations and experimental trials involving the 

construction, reconstruction or modification of a source if the project meets the criteria listed in 

paragraph (c)(7), as applicable. These criteria provide, among other things, that a temporary 

project cannot increase the PTE of the affected stationary source above the major source 

thresholds or by more than 15 tons, and the duration of the temporary operation or experimental 

trial must be less than 30 days. Additional restrictions are imposed on soil or water remediation 

projects in paragraph (c)(7)(D). Paragraph (c)(7)(E) provides that if the project would otherwise 

require a permit, then written notification must be provided to the Control Officer at least 7 days 

before it begins operation which describes the purpose of the project, why it qualifies for the 

exemption and anticipated dates of operation. Paragraph (c)(7)(F) provides that if the project 

would otherwise require a permit, then written notification must be provided to the Control Officer 
7

within 7 days after concluding the project which provides the actual date the project started and 

ended, and the actual emissions from the project. Finally, paragraph (c)(7)(G) states that 

exemptions provided under paragraph (c)(7) do not apply if the company’s normal course of 

business involves temporary and experimental operations. 

Subsection 12.1.3 (Permit Application), establishes requirements for permit applications, such as 

the duty to apply and obtain a minor source permit, the timing of required applications, the 

required contents of a complete application, requirements for obtaining a permit application 

shield, and the duty to supplement or correct a submitted application as appropriate. These 

procedures and requirements are necessary to ensure implementation of an enforceable permit 

program. Importantly, subsection 12.1.3 prohibits any person from commencing construction of, 

operating, or making a modification to a minor source except in compliance with a minor source 

permit authorizing such construction, operation, or modification. See Section 12.1, subsection 

12.1.3.1.

Subsection 12.1.4 (Permit Content), specifies the types of terms and conditions that Clark minor 

source permits must have. These include the identification of all applicable requirements, emission 

limits that ensure the protection of the NAAQS, and monitoring, testing, reporting, and 

recordkeeping requirements to verify compliance. This subsection also requires that all permits 

contain a statement that commencement of operation constitutes the permittee’s acknowledgment 

that it is responsible for ensuring that the source’s emission units and emission control equipment 

have been constructed and will be operated in compliance with all applicable requirements.

Subsection 12.1.5 (Permit Application Processing Procedures), specifies the conditions that must 

be met before Clark may issue a final permit, including receipt of a complete application, public 

notice procedures where required, and Clark’s determination that the source or emission units will 

not interfere with attainment and maintenance of the NAAQS. This subsection also establishes 

deadlines for the issuance or denial of a permit, which range from 75 to 150 days after the 

application is determined to be complete, depending on whether the action is for an existing or new 

minor source, a significant permit revision, or a permit renewal. The rule also addresses public 

notice requirements in this subsection, specifying which permitting actions require public notice 

based on emission thresholds and the location of the source. 

Subsection 12.1.6 (Revisions to an Existing Minor Source Permit), establishes the criteria for 

determining what types of changes at a minor source require a significant permit revision and what

types of changes may be allowed through other processes. “Significant permit revisions” must 

undergo public participation procedures as specified in subsection 12.1.5.3. For “minor permit 

revisions,” public notice is not required and the proposed modification may be implemented seven 

days after an application is submitted, unless Clark objects within this 7-day period. Clark is 

required to take a final action on a minor permit revision within 30 days of receipt. This subsection 

also establishes criteria for administrative permit revisions, changes that can be made with prior 

notice and changes that can be made with on-site logging.
8

Subsection 12.1.7 (Permits Containing Voluntarily Accepted Emission Limitations and 

Standards), contains the permit content requirements for sources that seek to limit their potential to 

emit in order to avoid being subject to requirements that would otherwise apply, including NSR 

and title V permitting requirements and Reasonably Available Control Technology (RACT) 

requirements.

Section 12.2 – Permit Requirements for Major Sources in Attainment Areas

This submittal contains Clark County’s regulations to implement the requirements of the

Prevention of Significant Deterioration (PSD) program in part C, title I of the Act and EPA’s 

implementing regulations in 40 CFR 51.160-164 and 51.166. This program applies to large new 

and modified sources of criteria pollutants for which Clark County has been designated as 

attainment or unclassifiable and certain other (non-criteria) pollutants subject to regulation under 

the CAA.

Section 12.3 – Permit Requirements for Major Sources in Nonattainment Areas

This submittal contains Clark County’s regulations to implement the requirements of the 

Nonattainment New Source Review (NSR) program in part D, title I of the Act and EPA’s 

implementing regulations in 40 CFR 51.160 through 51.165. This program applies to large new 

and modified sources of criteria pollutants for which Clark County (or a portion thereof) has been 

designated as nonattainment.

Section 12.4 – Authority to Construct Application and Permit Requirements for Part 70 Sources

Clark currently implements a combined NSR and Title V permit program. This means that any 

source required to obtain a PSD/NSR permit under Sections 12.2 or 12.3 must also comply 

simultaneously with the applicable part 70 operating permit requirements in Section 12.4. Section 

12.4 provides the administrative procedures for sources to apply for and obtain an Authority to 

Construct Permit (ATC Permit), consistent with the applicable requirements of Sections 12.2 or 

12.3.

Subsection 12.4.1 (Authority to Construct Permit Required; Duration), specifies the timing 

requirements for ATC Permits, such as requiring a source to obtain such permit prior to actual 

construction, the provisions under which the permit remains in effect, and when a Part 70 permit 

must also be obtained prior to commencing operation.

Subsection 12.4.2 (Definitions), contains definitions for terms used in this rule, and specifies the 

order in which other regulations may be referenced to define other terms used in the rule.

Subsection 12.4.3 (Authority to Construct Permit for Part 70 Sources), contains the required 

procedures for obtaining an ATC Permit. Paragraph 12.4.3.1 contains the application submission, 

processing and issuance requirements which apply if the project is subject to the requirements of 

Section 12.2 or 12.3. This includes the general application requirements, as well as the specific 

application requirements for sources subject to those Sections. In subparagraph (d), the rule 

provides the application processing procedures to be followed by Clark, such as the time period 

allowed for determining an application is complete. Subparagraph (e) lists all of the required
9

contents of an ATC Permit. Similarly, Paragraph 12.4.3.2 contains the application submission, 

processing and issuance requirements which apply if the project is not subject to the requirements 

of Section 12.2, 12.3 or subsection 12.4.3.3 (requirements applicable to MACT sources). Because

these projects are not subject to the control requirements of Section 12.2 or 12.3 (i.e., BACT or 

LAER), this paragraph specifies requirements for implementation of Reasonably Available 

Control Technology (RACT). Paragraph 12.4.3.3 specifies additional application requirements for 

a project subject to any of the construction or reconstruction provisions of CAA section 112(d), (f) 

or (h). Paragraph 12.4.3.4 contains the required procedures for revising an ATC Permit once it has 

been issued. Finally, Paragraph 12.4.3.5 identifies the administrative procedures for revising 

permit conditions subject to the CAA Title IV Acid Rain program.

Rule Evaluations

General Summary

For this Technical Support Document (TSD), EPA reviewed the submitted NSR rules for 

compliance with the CAA requirements for SIPs in general as set forth in CAA section 110(a)(2),

the requirements for stationary source preconstruction permitting programs in 40 CFR part 51, 

subpart I (Review of New Sources and Modifications), and the requirements related to SIP 

revisions in CAA sections 110(l) and 193. EPA also relied on the following materials in the review 

of Clark’s overall NSR regulations: General Preamble for the Implementation of Title I of the 

Clean Air Act Amendments of 1990 (see 57 FR 13498, April 16, 1992), EPA’s Emission Offset 

Interpretive Ruling (40 CFR part 51, appendix S), and EPA’s policy document entitled, 

“Improving Air Quality with Economic Incentive Programs,” that was published in January 2001. 

EPA has condensed the approval criteria contained in these various materials in this TSD, which 

describes reasons for our action on the NSR SIP submittal for Clark County.

Section 0 – Definitions

Clark County’s revisions to Section 0 added new terms that support the new Section 12 series of 

rules, updated terms to reflect their current meanings, and eliminated terms that are no longer used. 

These revisions represent an overall improvement to the current SIP rule by updating the terms and 

definitions used. The revisions do not directly affect emissions but clarify the application of other 

Clark County air pollution rules. EPA has reviewed each of the new and revised definitions and 

has determined that they are clear and consistent with the use of terms in other Clark rules and 

consistent with EPA definitions, where applicable. We identify below the Section 0 definitions

that Clark County has added, revised or deleted since EPA last approved Section 0 into the Clark 

County portion of the Nevada SIP (69 FR 54006, September 7, 2004).

New definitions added: Air Contaminants, Air Quality Planning Region, Commence 

Operation, Complete, Date of Submittal, Emission Limit or Emission Limitation, Excess 

Emissions, Good Engineering Practice (GEP), Insignificant Activities and Emissions, 

Operation and Maintenance Plan, PM2.5, Reasonably Available Control Technology 

(RACT), Reconstruction or Reconstruct, and Shutdown. 
10

Definitions revised: Administrator, Affected Source, Affected State(s), Airplane 

Refueling Area, Air Quality Area, Allowable Emissions, Applicable Requirement, Best 

Management Practice, British Thermal Unit, Building, Structure, Facility, or Installation, 

Building Vent, Commence, Control Officer, Construction, Disturbed Surface Area, Dust 

Palliative, Dust Suppressant, Emergency, Emission or Emit, Emissions Unit, EPA, 

Ethanol, Existing Emissions Unit, Existing Stationary Source, Federally Enforceable, Fuel, 

Fuel Oil, Fugitive Dust, Gasoline, Gasoline Dispensing Facility, Hazardous Air Pollutant, 

Hydrographic Basin Areas or Hydrographic Areas, Incinerator, Leak Free, Methyl Tertiary 

Butyl Ether, Motocross Race Course, Natural Cover, Nonattainment Area, Non-metallic 

Mineral, Non-Metallic Mineral Processing Plant, Non-Road Easement, Opacity, Opera 

Areas And Vacant Lots, Owner and/or Operator, Oxygenated Gasoline, Part 70 Operating 

Permit, Part 70 Source, Particulate Matter (PM), Pave or Paved, Person, PM10, Permanent,

Potential to Emit, Prime Coat, Public Road, Regulated Air Pollutant(s), Secondary 

Emissions, Single Coat, Stack, Stationary Source, Surplus, Top Off, Topsoil, Vapor 

Control System, Vapor Tight, and Volatile Organic Compound (VOCs).

Definitions deleted: Aggrieved Party, Asbestos, Banking, Baseline, Confidential 

Information, Designated Representative, Diesel Fuel, Easement, Easement Holder, 

Emergency Standby Generator, Emergency Standby Diesel Powered Generator, Exempt 

Stationary Source, Freeboard Ratio, Fugitive Gas, Garbage, Gas, Gasoline Station, General 

Permit, Hearing Board, Hearing Officer, Highly Volatile Solvent, Large Appliances, Low 

Organic Solvent Coating, Major Part 70 Source, Malfunction, Management Area, 

Maximum Achievable Control Technology (MACT), Maximum Achievable Control 

Technology (MACT) Floor, Modification, Modified Emission Unit, MTBE, Multiple 

Chamber Incinerator, Offset, Permit for Construction Activities, PM10 Nonattainment 

Area, Process Equipment, Proposed Permit, Reconstruction, Registry or Bank, 

Representative of Alleged Violator, Section 58 ERC Bank Certificate, Significant Source, 

Temporary Stationary Source, Total Suspended Particulate (TSP), Toxic Chemical 

Substance (TCS), Trench, Upset/Breakdown, Vacant Lot, Various Locations Activity, and 

Waste.

Definitions moved to Section 12.2 and revised: Baseline Area, Baseline Emissions, 

Baseline Concentration, Baseline Area, Baseline Concentration, Baseline Area, Baseline 

Concentration, Begin Actual Construction, Best Available Control Technology, Major 

Modification, Major Stationary Source, Baseline Area, Baseline Concentration, Net 

Emissions Increase, Non Major Source Baseline Date (New term is “minor source baseline 

date”), Prevention of Significant Deterioration (PSD) Program, PSD, Trigger Date. 

Definitions moved to Section 12.3 and revised: Baseline Emissions, Begin Actual 

Construction, Best Available Control Technology, Emission Reduction Credit (ERC), 

Lowest Achievable Emission Rate, Major Modification, Major Stationary Source, Net 

Emissions Increase.

Title V related definitions moved to Section 12.5 and revised: Operating Permit, Part 
11

70 Permit Modification, Part 70 Permit Revision, Part 70 Program, Responsible Official, 

Section 502(B)(10) Changes.

Section 12.0 – Applicability, General Requirements and Transition Procedures

This rule summarizes the applicability provisions of the Section 12 permitting programs as Clark

makes the transition from the old to the new permitting rules. Section 12.0 does not in itself 

establish any substantive permitting requirements but instead establishes timeframes for the 

applicability of the new rules to stationary sources that had been subject to Clark’s previous 

permitting rules. The rule is designed to ensure a smooth transition between the old and new 

permitting programs to be carried out under these rules. This rule is clear and enforceable, and 

appropriate for approval into the SIP.

It should be noted that, pursuant to State law, the State of Nevada, not a local air district, has 

jurisdiction over plants which generate electricity by using steam produced by the burning of fossil 

fuel within the State of Nevada. The applicable State law, now codified in Nevada Revised 

Statutes (NRS) 445B.500, was approved by EPA in 1980 as NRS 445.546(4). See 45 FR 46384 

(July 10, 1980) (codified at 40 CFR 52.1470(b)(14)(ii)). Thus, the State, not Clark County, has 

jurisdiction over such plants that are located or that will be constructed within Clark County. The 

Section 12 permit programs therefore apply to any stationary source located in Clark County, 

except for a plant which generates electricity by using steam produced by the burning of fossil fuel, 

which is subject to NDEP’s jurisdiction. See Section 12.0, subsection 12.0.1(a).

Section 12.1 – Permit Requirements for Minor Sources

We reviewed this rule for compliance with EPA’s regulations in 40 CFR 51, subpart I, excluding 

40 CFR 51.165 and 51.166, which apply only to new major sources and major modifications under 

parts C and D of title I of the CAA. 

1. 40 CFR 51.160 – Legally enforceable procedures

(a) Each plan must set forth legally enforceable procedures that enable the State or local 

agency to determine whether the construction or modification of a facility, building, 

structure or installation or combination of these will result in (1) a violation of applicable 

portions of the control strategy; or (2) interference with attainment or maintenance of a 

national standard in the state in which the proposed source (or modification) is located or in 

a neighboring State.

Discussion: Subsections 12.1.3.2 and 12.1.3.3 establish requirements for sources to submit timely 

and complete permit applications. Subsection 12.1.3.6 requires that each permit application identify, 

among other things, the potential to emit (PTE) of all regulated air pollutants emitted from each 

emission unit and provide detailed information about equipment and fuels used. Subsection 12.1.4 

requires that each minor source permit issued by Clark include emission limitations that ensure that 

“[t]he ambient air quality standards will be attained or maintained” (12.1.4.1(c)) and emission 

limitations and standards (including operational requirements) necessary to “ensure that any 

ambient air increment as prescribed by subsection 12.2.3 is not exceeded” (12.1.4.1(f)). Finally, 
12

subsection 12.1.5.1 requires that Clark determine, as a precondition to permit issuance, that the 

permit terms “provide for compliance with all applicable requirements.” See Clark County DAQ, 

Technical Support Document, Sections 0 & 12, “Chapter 3: Technical Support Document for 

Sections 0, 12.0, 12.1, and 12.11,” at 3-20, 3-21 (October 21, 2009) (hereinafter “Minor NSR TSD”).5

These provisions are legally enforceable and generally provide information specific enough to enable 

Clark to determine whether a new or modified minor source would violate any applicable portion of 

the control strategy or interfere with attainment or maintenance of the NAAQS, as required by 40 

CFR 51.160(a). These provisions are acceptable to satisfy this requirement, with one significant 

exception. The term “ambient air quality standards” in subsection 12.1.4.1(c) appears to be in 

reference to Clark’s ambient air quality standards in Section 11, which are not entirely consistent with 

the NAAQS. Section 11, which EPA approved into the SIP on September 7, 2004 (69 FR 54006), 

defines “ambient air quality standards” and related provisions consistent with most of the NAAQS but 

does not include the 2006 24-hour PM2.5 NAAQS (35 ug/m3) or the 2008 Lead (Pb) NAAQS (15 

ug/m3, rolling 3-month average). See 40 CFR 50.13 and 50.16. We propose to disapprove Section 

12.1 to the extent it does not address these revised NAAQS. This limited disapproval, if finalized, 

would require Clark to revise Section 12.1 to address the requirements of 40 CFR 51.160-164 with 

respect to EPA’s revised NAAQS for PM2.5 and Lead.

EPA also revised the NAAQS for NO2 and SO2 in 2010, and minor NSR SIP revisions to implement 

these standards are due January 22, 2013 and June 2, 2013, respectively. See 75 FR 6474 

(February 9, 2010) (final rule establishing new 1-hour standard for NO2) and 75 FR 35520 (June 22, 

2010) (final rule establishing new 1-hour standard for SO2). Although these NSR SIP submissions 

are not yet due, we recommend that Clark include provisions necessary to implement these new 

NAAQS in a revised SIP submission in response to our proposed limited approval and limited 

disapproval of Section 12.1.

We note that it is not entirely clear how Clark would establish emission limitations meeting the 

requirements of subsection 12.1.4(c) and 12.1.4(f) in the absence of any requirement in Section 12.1 

for permit applicants to evaluate air quality impacts (through air quality modeling or otherwise), and 

we encourage Clark to reevaluate these provisions at its earliest opportunity to address this issue. 

According to 2003-2006 emissions inventory information submitted by Clark County, emissions from 

minor stationary sources in Clark County comprise, for most NAAQS pollutants, less than 3% of total 

inventoried emissions in the county, and roughly 19% of total inventoried VOC emissions in the 

county are attributed to minor source emissions. See Appendix D – Emission Inventory Tables, in 

“Proposed Revision To The Clark County Part Of The Nevada State Implementation Plan: Minor 

Source New Source Review Program Rule Adoptions And Revisions,” January 29, 2009 (“Minor 

NSR SIP Submittal”); see also Memorandum to File dated July 10, 2012, Laura Yannayon, EPA 

Region 9, RE: “EPA evaluation of Clark County minor source emissions,” including attachment. Clark 

County’s supporting documentation states that neither of the attainment/maintenance 

demonstrations for CO or PM10 for the area relied on any permit requirements for CO or PM10

emissions because of the de minimis impact of stationary source emissions on ambient levels of 

 5 Included as Chapter 3 in “Proposed Revision To The Clark County Part Of The Nevada State Implementation Plan: 

Minor Source New Source Review Program Rule Adoptions And Revisions,” January 29, 2009 (hereinafter “Minor 

NSR SIP Submittal”).
13

these pollutants, and that none of the control strategies in the Nevada SIP rely upon regulation of 

new minor sources or modifications to existing minor sources. See Minor NSR TSD at 3-20, 3-21, 

3-26 and 3-27. Given Clark’s documentation of the insignificant portion of total inventoried emissions 

attributed to minor sources in Clark County, we believe it is reasonable for Clark to implement a 

minor NSR program that does not require individual source impacts analyses.

(b) Such procedures must include means by which the State or local agency responsible for 

final decision-making on the application for approval to construct or modify will prevent 

such construction or modification if (1) it will result in a violation of applicable portions of 

the control strategy; or (2) it will interfere with the attainment or maintenance of a national 

standard.

Discussion: Subsection 12.1.3.1 prohibits any person from commencing construction of, operating, 

or making a modification to a minor source “except in compliance with a minor source permit that 

authorizes such construction, operation, or modification.” Subsection 12.1.5.1(a) states that a new 

minor source permit, significant permit revision or permit renewal may be issued only if certain 

conditions are met, including a requirement that the Control Officer determine 1) that the permit 

conditions provide for compliance with all applicable requirements (including the SIP) and 2) that the 

source will not interfere with attainment and maintenance of the NAAQS. These provisions are 

acceptable to satisfy this requirement.

(c) The procedures must provide for the submission, by the owner of operator of the 

building, facility, structure, or installation to be constructed or modified, of such 

information on (1) the nature and amounts of emissions to be emitted by it or emitted by 

associated mobile sources; (2) the location, design, construction, and operation of such 

facility, building, structure, or installation as may be necessary to permit the State or local 

agency to make the determination referred to in paragraph (a) of this section.

Discussion: Subsection 12.1.3.6 – Application Contents, specifies the required application submittal 

information. The information specified is sufficient for Clark to make the determinations referred to in 

40 CFR 51.160(a). This provision is generally acceptable to satisfy this requirement. However, we 

cannot approve subsection 12.1.3.6(a)(5), which purports to limit Federal enforcement authority by

providing that an applicant may state that “it wants the entire permit, or specifically identified permit 

conditions or applicable requirements, to be federally enforceable.” Although title V operating permits 

issued under an approved part 70 program may, in some cases, distinguish federally-enforceable 

permit provisions from State-only provisions, this is not permissible for minor NSR purposes, as all 

conditions of a permit issued pursuant to a SIP-approved permit program are federally enforceable.

See CAA 113, 304; see also 40 CFR 52.23. We therefore propose to disapprove this provision. This

limited disapproval, if finalized, would require Clark to revise subsection 12.1.3.6 to delete the 

language in subparagraph (a)(5) regarding federal enforceability. As a general matter, we note that 

any statement contained in a permit application regarding federal enforceability has no effect

whatsoever on EPA’s or citizens’ enforcement authorities under sections 113 and 304 of the Act.

(d) The procedures must provide that approval of any construction or modification must 

not affect the responsibility on the owner or operator to comply with applicable portions of 
14

the control strategy.

Discussion: Section 12.1 does not contain a provision to satisfy this requirement. EPA is identifying 

the lack of such a provision as a deficiency and proposing to disapprove Section 12.1 with respect to 

this requirement. This limited disapproval, if finalized, would require Clark to revise Section 12.1 to 

include a provision meeting the requirement in 40 CFR 51.160(d) and to submit the revised rule to 

EPA for approval into the Clark County portion of the Nevada SIP.

(e) The procedures must identify types and sizes of facilities, buildings, structures, or 

installations which will be subject to review under this section. The plan must discuss the 

basis for determining which facilities will be subject to review.

Discussion: Section 12.1 applies to “any stationary source located in Clark County that has the 

potential to emit (PTE) a regulated air pollutant [in amounts] equal to or greater than the thresholds 

listed in subsection 12.1.1(c), but less than the major source thresholds listed in 12.2.2.1(ff) or

12.3.2(y).” Subsection 12.1.0; see also subsection 12.1.1(a) (defining “exempt stationary source”). 

Subsection 12.1.1 defines “minor source” as a source not required to obtain a permit pursuant to 

Section 12.4, subsection 12.4.3 or Part 70 and that has a potential to emit equal to or greater than 

specified thresholds for six criteria pollutants6 (pollutants for which EPA has established national 

ambient air quality standards) and H2S. These thresholds range from 0.3 tons per year (tpy) for lead, 

to 25 tpy for CO. See subsection 12.1.1(c). Section 12.1 identifies specific types of emission units 

and activities that are exempt from the requirement to obtain a Section 12 permit (subject to specified 

conditions), such as medical or veterinary laboratories devoted to experimental study, teaching, or 

the testing and analysis of substances not sold or distributed commercially. See subsections

12.1.2(a) and (c). Emission units or activities listed in subsection 12.5.2.5 are also covered by this 

exemption. See subsection 12.1.2(a). Clark established these emission thresholds and “categorical 

exemptions” by balancing the need to ensure that facilities that impact air quality have permits

against the need to exempt sources that have insignificant or no impacts on air quality. See Minor 

NSR TSD at 3-3. The actual number of sources that currently hold permits and that would no longer 

need individual permits under the revised Section 12.1 requirements is approximately 190 sources or 

less than one percent of total sources, and according to Clark, these are extremely small sources 

with very little or no impact on ambient air quality. See id. at 3-4; see also Memorandum to File dated 

July 10, 2012, Laura Yannayon, EPA Region 9, RE: “Number of minor NSR permitted sources.”

Subsection 12.1.6 contains the requirements for revisions to existing minor source permits and 

identifies the types of changes subject to “Significant,” “Minor” or “Administrative” permit revisions, as 

well as changes that can be made with “Prior Notice” or “On-site Logging.” Importantly, a “Significant 

Permit Revision” includes any modification that increases the source’s potential to emit (PTE) a 

regulated air pollutant by an amount equal to or exceeding the “significant” levels in subsection 

12.1.1(g), and may not be made without a permit issued pursuant to the procedures in subsections

12.1.3 and 12.1.5. See subsection 12.1.6(a). The “significant” levels in subsection 12.1.1(g) range 

from 0.6 tpy for lead (Pb) to 40 tpy for sulfur dioxide (SO2). Other types of minor source permit 

revisions in subsections 12.1.6(b), (c), (d), and (e) (i.e., for “minor permit revisions,” “administrative 

 6 As noted further below, Section 12.1 does not apply to minor sources of PM2.5. 
15

permit revisions,” changes that can be made with “prior notice,” and changes that can be made with 

“on-site logging”) are not subject to public process and generally may proceed unless Clark objects 

within a specified number of days after the permittee has provided some form of notice.

EPA regulations in 40 CFR 51.160(e) allow state NSR programs to exclude new minor sources and 

minor modifications from the NSR program so long as such sources and modifications are not 

environmentally significant, consistent with the de minimis exemption criteria set forth in Ala. Power 

Co. v. Costle, 636 F.2d 323, at 360-361 (D.C. Cir. 1979).7 In this instance, we believe that the 

emissions-based thresholds and categorical exemptions in subsections 12.1.1(c) and 12.1.2 and the 

emissions-based thresholds for “significant” permit revisions in subsection 12.1.1(g) generally 

represent well-defined objective criteria and are reasonably calculated to exclude from review only 

less environmentally significant sources and modifications, based on Clark’s evaluation of the 

insignificant portion of total stationary source emissions attributed to minor sources. These 

provisions are acceptable, with one exception: the exemption in subsection 12.1.2(a) for emission 

units or activities listed in subsection 12.5.2.5 is not approvable because Section 12.5 is neither 

approved into the SIP nor included in the NSR SIP submittal, and we therefore have no basis for 

concluding that the exemption is appropriate for minor NSR purposes. We propose to disapprove this 

provision. This limited disapproval, if finalized, would require Clark to either revise subsection 

12.1.2(a) to remove the exemption for emission units or activities identified in Section 12.5, or to 

submit the relevant portions of Section 12.5 for approval into the Clark County portion of the Nevada 

SIP.

With respect to the additional provisions for minor source permit revisions in subsections 12.1.6(b) 

through (e) (i.e., for “minor permit revisions,” “administrative permit revisions,” changes that can be 

made with “prior notice,” and changes that can be made with “on-site logging”), we find these 

provisions to be acceptable to the extent that they apply only to physical or operational changes at a 

minor source that do not increase the source’s PTE by “significant” amounts. See, e.g., subsections 

12.1.6(b)(2)(A) and 12.1.6(d)(2). We recommend, however, that Clark revise subsection 12.1.6(d)(5)

to clarify that this provision does not cover changes that may increase the source’s PTE by 

“significant” amounts. Additionally, we note that the reference to paragraph (2)(E) in subsection 

12.1.6(b) appears to be a typographical error and should be corrected by replacing (E) with (D).

Finally, Section 12.1 is broadly deficient in one important respect. The definition of “minor source” in 

 7 While the Alabama Power court discusses the de minimis principle in the context of a Federal administrative 

agency’s authority in promulgating rules to satisfy statutory requirements, the same principle can be applied where a 

State promulgates rules to satisfy requirements by a Federal administrative agency. With regards to the de minimis 

principle, the Alabama Court writes: “Determination of when matters are truly de minimis naturally will turn on the 

assessment of particular circumstances, and the agency will bear the burden of making the required showing. But we 

think most regulatory statutes, including the Clean Air Act, permit such agency showings in appropriate cases. While 

the difference is one of degree, the difference of degree is an important one. Unless Congress has been extraordinarily 

rigid, there is likely a basis for an implication of de minimis authority to provide exemption when the burdens of 

regulation yield a gain of trivial or no value. That implied authority is not available for a situation where the regulatory 

function does provide benefits, in the sense of furthering the regulatory objectives, but the agency concludes that the 

acknowledged benefits are exceeded by the costs. For such a situation any implied authority to make cost-benefit 

decisions must be based not on a general doctrine but on a fair reading of the specific statute, its aims and legislative 

history.” See Ala. Power Co. v. Costle, 636 F.2d 323, at 360-361 (D.C.Cir. 1979).
16

subsection 12.1.1(c) does not address PM2.5 emissions. Pursuant to CAA section 110(a)(2)(C), 

States were required to amend their minor source programs to include direct PM2.5 emissions and 

precursor emissions in the same manner as included for purposes of PM2.5 major NSR. See 73 FR 

28321, 28344 (May 16, 2008). Because Nevada has not yet submitted the required minor NSR SIP 

revisions to address the 1997 PM2.5 standard, EPA is proposing to disapprove the applicability 

provisions of Section 12.1 to the extent they do not address minor sources of PM2.5 and PM2.5

precursor emissions. This limited disapproval, if finalized, would require Clark to revise Section 12.1 

to cover minor sources of PM2.5 and to submit the revised rule to EPA for approval into the Clark 

County portion of the Nevada SIP.

(f) The procedures must discuss the air quality data and the dispersion or other air quality 

modeling used to meet the requirements of this subpart. (1) All applications of air quality 

modeling involved in this subpart shall be based on the applicable models, data bases, and 

other requirements specified in appendix W of this part (Guidelines on Air Quality 

Models). (2) Where an air quality model specified in appendix W of this part (Guideline on 

Air Quality Models) is inappropriate, the model may be modified or another model 

substituted. Such a modification or substitution of a model may be made on a case-by-case 

basis or, where appropriate, on a generic basis for a specific State program. Written 

approval of the EPA must be obtained for any modification or substitution. In addition, use 

of a modified or substituted model must be subject to notice and opportunity for public 

comment under procedures set forth in 40 CFR 51.102.

Discussion: Although any air quality data or modeling used to meet a requirement in a minor NSR

program must comply with EPA’s requirements in 40 CFR part 51, appendix W, or an approved 

alternative consistent with 40 CFR 51.160(f), EPA’s regulations do not specifically require that all 

minor source permit programs contain requirements for air quality modeling. Because Section 12.1 

does not require permit applicants to conduct air quality modeling analyses, the requirement in 40 

CFR 51.160(f) related to air quality data and models does not apply to our evaluation. The absence 

of a specific air quality modeling provision in Section 12.1 is acceptable given the relatively 

insignificant portion of total stationary source emissions attributed to minor sources in Clark County, 

as discussed above. See Minor NSR SIP Submittal, Appendix D – Emission Inventory Tables; see 

also Memorandum to File dated July 10, 2012, Laura Yannayon, EPA Region 9, RE: “EPA evaluation 

of Clark County minor source emissions,” including attachment, and Minor NSR TSD at 3-20, 3-21, 

3-26 and 3-27. 

2. 40 CFR 51.161 – Public availability of information

(a) The legally enforceable procedures in 40 CFR 51.160 must also require the State or 

local agency to provide opportunity for public comment on information submitted by 

owners and operators. The public information must include the agency’s analysis of the 

effect of construction or modification on ambient air quality, including the agency’s 

proposed approval or disapproval.

Discussion: Section 12.1, subsection 12.1.5 requires Clark to provide an opportunity for public 

comment prior to issuing a permit for the construction or modification of three specific categories of 
17

minor sources. Clark established these categories of minor sources based on a review of its 

emissions inventories and a conclusion that only these emission sources are environmentally 

significant. See Minor NSR TSD at 3-3, 3-4. Specifically, subsection 12.1.5.3(a) requires Clark to 

publish a notice of proposed action on an application for the following types of sources:

(1) any new minor source with a potential to emit that exceeds 50 tpy for CO, 40 tpy for VOC, 

SO2, or NOx, 15 tpy for PM10, or 0.6 tpy for lead,

(2) any new minor source that will be located within 1,000 feet of the outer boundary of a school, 

hospital, or residential area, and 

(3) any “significant permit revision” that is required because of a “significant” (as defined in the 

rule) increase in an existing minor source’s potential to emit.

As discussed above, EPA regulations in 40 CFR 51.160(e) allow State NSR programs to exclude 

new minor sources and minor modifications from the NSR program so long as such sources and 

modifications are not environmentally significant, consistent with the de minimis exemption criteria 

set forth in Ala. Power Co. v. Costle, 636 F.2d 323, at 360-361 (D.C. Cir. 1979). Given that 40 CFR 

51.160(e) allows for sources and modifications that are not environmentally significant to be 

excluded entirely from the NSR program, it follows that a State or local agency can choose to exempt 

some new sources or modifications subject to permitting from public participation requirements, but it 

must do so consistent with the de minimis principles and by application of well-defined objective 

criteria. Thus, EPA believes that 40 CFR 51.161(a) allows for the tailoring of the public participation 

process for less environmentally significant sources and modifications. See, generally, 60 FR 45530, 

at 45548-45549 (August 31, 1995). Section 12.1 essentially treats all sources not covered by the 

public notice provisions in subsection 12.1.5.3(a)(1) as de minimis. We believe that these

emissions-based thresholds represent well-defined objective criteria and, based on Clark’s 

documentation of the relatively insignificant portion of total inventoried emissions attributed to minor 

stationary sources in Clark County (See Minor NSR SIP Submittal, Appendix D – Emission Inventory 

Tables; see also Memorandum to File dated July 10, 2012, Laura Yannayon, EPA Region 9, RE: 

“EPA evaluation of Clark County minor source emissions,” including attachment, and Minor NSR 

TSD at 3-20, 3-21, 3-26 and 3-27) we find that the thresholds established in subsection 

12.1.5.3(a)(1) are reasonably calculated to exclude from mandatory public participation only less 

environmentally significant sources and modifications. This is acceptable.

(b) For the purposes of paragraph (a) of this section, opportunity for public comment shall 

include, as a minimum, (1) Availability for public inspection in at least one location in the 

area affected of the information submitted by the owner or operator and of the State or local 

agency’s analysis of the effect on air quality; (2) A 30-day period for submittal of public 

comment; and (3) A notice by prominent advertisement in the area affected of the location 

of the source information and analysis specified in paragraph (b)(1) of this section. 

Discussion: Section 12.1 establishes adequate public participation procedures for those new 

sources or modifications subject to public notice under subsection 12.1.5.3(a)(1). For instance, 

subsection 12.1.5.3 provides for notice to the public via publication of a Notice of Proposed Action in 

both a newspaper of general circulation in Clark County and on Clark’s website, and specifies that all 

notices of proposed actions include the Control Officer’s preliminary determination whether the 

application for a permit should be approved. Subsection 12.1.5.3 also specifies that Clark’s public 
18

notices must identify the location of the administrative record and information on how the public can 

obtain additional information such as the draft permit, statement of basis, application, and other 

relevant supporting materials. The rule establishes a 30-day comment period for submission of 

written comments. These provisions are acceptable to satisfy this requirement.

(c) Where the 30-day comment period required in paragraph (b) of this section would 

conflict with existing requirements for acting on requests for permission to construct or 

modify, the State may submit for approval a comment period which is consistent with such 

existing requirements.

Discussion: This is a discretionary component of a permit program that Clark’s submitted regulations 

do not contain. All permits subject to public notice requirements under Section 12.1 are subject to a

30-day public comment period. This is acceptable. 

(d) A copy of the notice required by paragraph (b) of this section must also be sent to the 

EPA through the appropriate Regional Office, and to all other State and local air pollution 

control agencies having jurisdiction in the region in which such new or modified 

installation will be located. The notice also must be sent to any other agency in the region 

having responsibility for implementing the procedures required under this subpart. For 

lead, a copy of the notice is required for all point sources. The definition of point source for 

lead is given in 40 CFR 51.100(k)(2).

Discussion: Subsection 12.1.5.3 requires that Clark notify officials and agencies having jurisdiction 

over the location where the proposed construction would occur. It also requires that a notice be sent 

to EPA if the project is for a voluntarily accepted emission limit (i.e., if the action creates a synthetic 

minor source). For other minor source actions, the rule requires that the notice be sent to EPA upon 

EPA’s request. With respect to any “point source” of lead (i.e., any stationary source that actually 

emits a total of 5 tpy or more, see 40 CFR 51.100(k)), the requirement is met because the public 

procedures in subsection 12.1.5.3 apply to any new minor source with a PTE that exceeds 0.6 tpy for 

lead. This provision is acceptable to satisfy this requirement.

3. 40 CFR 51.162 – Identification of responsible agency

Each plan must identify the State or local agency which will be responsible for meeting the 

requirements of this subpart in each area of the State. Where such responsibility rests with 

an agency other than an air pollution control agency, such agency will consult with the 

appropriate State or local air pollution control agency in carrying out the provisions of this 

subpart.

Discussion: Nevada law identifies the State Department of Conservation and Natural Resources 

(DCNR) as the State agency responsible for issuing permits to new or modified sources in all areas 

of the State of Nevada, except within counties whose populations exceed 100,000. In such counties, 

Nevada law provides that the applicable permitting agency is the district board of health, county 

board of health or board of county commissioners. See NRS 445B.300 and NRS 445B.500, both of 

which were approved on August 31, 2006 (71 FR 51766). Clark County is one of only two counties in 
19

Nevada whose populations exceed 100,000, and the County has its own air pollution control agency. 

Section 12.0 identifies Clark as the agency that will be implementing stationary source permitting 

requirements in Clark County, including Section 12.1.

The only exception to this basic regulatory structure for permitting of sources in Nevada relates to 

certain power plants that are subject to State, not county, jurisdiction notwithstanding their location 

within Clark County. See NRS 445B.500(5), approved into the SIP as noted above; see also Section 

12.0, subsection 12.0.1. Thus, the Nevada SIP identifies the State or local agency which is 

responsible for meeting the requirements of 40 CFR part 51, subpart I, in Clark county.

4. 40 CFR 51.163 – Administrative procedures

The plan must include the administrative procedures, which will be followed in making the 

determination specified in paragraph (a) of 40 CFR 51.160.

Discussion: Section 12.1 provides adequate administrative procedures to be followed by Clark in 

making the determinations specified in 40 CFR 51.160(a), including application requirements, and 

specifically, requirements for environmental evaluations, as well as completeness determinations, 

preliminary findings, public participation, and considerations in the final decision to issue or deny a 

permit. See, e.g., subsections 12.1.3, 12.1.4, and 12.1.5.

5. 40 CFR 51.164 – Stack height procedures

Such procedures must provide that the degree of emission limitation required of any source 

for control of any air pollutant must not be affected by so much of any source’s stack height 

that exceeds good engineering practice or by any other dispersion technique, except as 

provided in 40 CFR 51.118(b). Such procedures must provide that before a State issues a 

permit to a source based on a good engineering practice stack height that exceeds the height 

allowed by 40 CFR 51.100(ii)(1) or (2), the State must notify the public of the availability 

of the demonstration study and must provide opportunity for public hearing on it. This 

section does not require such procedures to restrict in any manner the actual stack height of 

any source.

Discussion: Section 12.1 does not contain any provisions designed to ensure that the air quality 

impacts of stationary sources are not underestimated due to stack heights that exceed good 

engineering practice or air dispersion modeling techniques that do not satisfy the criteria of set forth 

in CFR 51.118(b). While such requirements are included in subsection 12.2.7.1, those provisions do 

not apply to minor sources as required by 40 CFR 51.164. EPA is identifying the absence of such a 

provision as a deficiency and proposing to disapprove Section 12.1 with respect to this requirement.

This limited disapproval, if finalized, would require Clark to revise Section 12.1 to include a provision 

meeting the requirement in 40 CFR 51.164 and to submit the revised rule to EPA for approval into the 

Clark County portion of the Nevada SIP.
20

Section 12.2 – Permit Requirements for Major Sources in Attainment Areas

EPA offers States (and local air districts) two mechanisms by which to administer permitting 

programs for the prevention of significant deterioration (PSD) of air quality, established by 

Congress in part C of title I of the Act. First, where EPA has promulgated the Federal PSD

program in 40 CFR 52.21, EPA may delegate that permitting authority to a State or air district. The 

Federal PSD program in 40 CFR 52.21 currently applies throughout the State of Nevada, except 

with respect to sources under Clark’s jurisdiction. See 40 CFR 52.1485 and 47 FR 26621 (June 21, 

1982), as amended 48 FR 28271 (June 21, 1983), 68 FR 11323 (March 10, 2003) and 68 FR 74489 

(December 24, 2003). Effective May 27, 1983, EPA delegated to NDEP full authority to 

implement the Federal PSD program with respect to sources under NDEP’s jurisdiction, including

plants which generate electricity by using steam produced by the burning of fossil fuel within the 

State of Nevada. NDEP now administers this Federal PSD program under a delegation agreement 

with EPA executed October 19, 2004, as amended September 15, 2011.

8 As a result, NDEP 

administers the Federal PSD program as it applies to major new or major modifications at plants 

which generate electricity by using steam produced by the burning of fossil fuel in Clark County.

Alternatively, a State or air district may develop its own PSD program meeting the requirements of 

40 CFR 51.166, and submit these rules for inclusion in the applicable SIP. Sources under Clark’s 

jurisdiction have been subject to a SIP-approved PSD program since June 21, 1982 (47 FR 26621). 

We discuss below the criteria for approval of a State/local PSD permitting program and our 

evaluation of Clark’s NSR SIP submittal in accordance with these requirements.

1. Provisions, pursuant to 40 CFR 51.166(a)(7), which incorporate the requirements in 40 

CFR 51.166(a)(7)(i) through (a)(7)(vi) regarding applicability of PSD program 

requirements.

Discussion: Section 12.2, subsection 12.2.1 (Applicability Procedures) contains all of the applicability 

procedures for sources located in areas designated as attainment or unclassifiable under the CAA. 

Subsection 12.2.1.4 (Projects) addresses the specific requirements of 40 CFR 51.166(a)(7). 

2. Applicable definitions found in CAA sections 169 and 169A(g), and in 40 CFR 51.100 and 

51.166(b). EPA has reviewed the definitions in Clark Sections 0 and 12.2. In most cases, 

the Clark definitions are either identical or nearly identical to the definitions in the CAA 

and EPA’s implementing regulations. In some cases, however, the Clark definitions do not 

track the language in the federal definitions as closely. We explain below in more detail our 

proposed determinations as to whether these definitions are equivalent to the federal 

definitions and, therefore, adequate to meet these requirements of a PSD program. 

 8 See “Agreement for Delegation of the Federal Prevention of Significant Deterioration (PSD) Program by the United 

States Environmental Protection Agency, Region 9 to the Nevada Division of Environmental Protection,” executed 

September 15, 2011. For sources locating in Washoe County, the Washoe County District Health Department

administers the Federal PSD program under a delegation agreement with EPA executed March 13, 2008.
21

A. Definitions That Differ From EPA Definitions in 40 CFR 51.166

Allowable emissions

Section 51.166 defines this term as “the emissions rate of a stationary source calculated using 

the maximum rated capacity of the source (unless the source is subject to federally enforceable

limits which restrict the operating rate, or hours of operation, or both) and the most stringent of 

several types of emission limits, including “[t]he emissions rate specified as a federally 

enforceable permit condition.” 40 CFR 51.166(b)(16) (emphases added). Clark’s definition in 

subsection 12.2.2(b) uses the term “practically enforceable” in lieu of “federally enforceable” and 

allows permit conditions with future compliance dates to be used to determine allowable 

emissions. Use of the term “practically enforceable” instead of “federally enforceable” is 

permissible only if the rule includes criteria by which a limit will be judged to be practically 

enforceable by Clark County. See, e.g., "Guidance on Limiting Potential to Emit in New Source 

Permitting," June 13, 1989; “Options for Limiting the Potential to Emit (PTE) of a Stationary 

Source Under Section 112 and Title V of the Clean Air Act (Act),” January 25, 1995 (a 

“practicably enforceable” permit limit must generally specify a technically-accurate limitation,

time period(s) for the limitation, and methods to determine compliance including appropriate 

monitoring, recordkeeping, and reporting). The absence of any such criteria is a deficiency. 

In addition, because permit conditions with future compliance dates generally are not practically 

enforceable at the time of permit evaluation, such permit conditions cannot provide a basis for 

calculating allowable emissions. We therefore propose to disapprove this definition. This limited 

disapproval, if finalized, would require Clark to revise the definition of “allowable emissions” to: 

(1) provide criteria for determining whether a particular limit is “practically enforceable” 

consistent with EPA policy, and (2) delete the reference to permit conditions with future 

compliance dates.

Baseline actual emissions

The definition of the term “Baseline Actual Emissions” (BAE) in subsection 12.2.2(c) varies in 

several respects from EPA’s definition in 40 CFR 51.166(b)(47). 

First, although EPA’s definition of BAE requires the inclusion of emissions associated with 

malfunctions (see 40 CFR 51.166(b)(47)(i)(a) and (ii)(a)), paragraphs (1)(A) and (2)(B) of 

subsection 12.2.2(c) requires the exclusion of “emissions from a shutdown associated with a 

malfunction.” However, the definition of the term “Projected Actual Emissions” in paragraph 

(nn)(1)(C) of subsection 12.2.2 also requires exclusion of emissions from a shutdown associated 

with a malfunction. On balance EPA believes this approach will result in equivalent or higher 

estimates of emission increases for modified emission units, since the emissions associated with 

future malfunctions should generally be estimated as the same or less when using newer 

modified equipment than malfunction-related emissions in a baseline year. Therefore, the 

omission of the requirement to include malfunction emissions in the BAE is acceptable.

Second, paragraph (1)(B)(i) of subsection 12.2.2(c) includes a requirement to adjust the BAE

downward to “exclude any emissions that would have exceeded an emission limitation with 

which the major stationary source must comply as of the particular date, had such major 
22

stationary source been required to comply with such limitations during the consecutive 24-month

period” (emphasis added). EPA’s definition of BAE in 40 CFR 51.166 includes a similar provision

for existing non-electric utility steam generating units (non-EUSGUs) but requires a downward 

adjustment in BAE “to exclude any emissions that would have exceeded an emission limitation 

with which the major stationary source must currently comply, had such major stationary source 

been required to comply with such limitations during the consecutive 24-month period.” 40 CFR 

51.166(b)(47)(ii)(c). The reference in paragraph (1)(B)(i) to an emission limitation that applied 

“as of the particular date” instead of an emission limitation with which the source must “currently 

comply” is problematic, as it is not clear which “particular date” the definition refers to. We 

propose to disapprove this provision. This limited disapproval, if finalized, would require Clark to 

revise the definition of BAE to define “particular date.”

We note, however, that to the extent that Clark intended to apply the requirement in 40 CFR 

51.166(b)(47)(ii)(c) (which only applies to non-EUSGUs), to both EUSGUs and non-EUSGUs, 

this is acceptable as it ensures that the calculation of BAE in both cases will exclude emissions 

that exceed current emission limitations.

We also recommend that subparagraph (1)(B)(i) be relabeled as a separate paragraph ((1)(C)

or(1)( E)) under subsection 12.2.2(c), as it is not appropriate to characterize it as a subset of 

paragraph (1)(B). See 40 CFR 51.166(47)(ii). Other provisions that cross-reference 

subparagraph (1)(B)(i) will then need to be revised accordingly. For example, paragraph (1)(D) 

will need to be revised to include a reference to the new paragraph (current subparagraph 

(1)(B)(i), relabeled as appropriate). See 40 CFR 51.166(47)(ii)(e).

Net emissions increase

The definition of the term “Net Emissions Increase” (NEI) in subsection 12.2.2(ii) varies in 

several respects from EPA’s definition in 40 CFR 51.166(b)(3).

Specifically, Clark’s definition of NEI includes three subparagraphs under subsection (1)(C) that 

are not included in EPA’s definition of NEI in 40 CFR 51.166(b)(3). These three subparagraphs

appear to establish requirements for calculating “actual emissions after the contemporaneous 

project,” but it is not clear what purpose these calculations serve and also not clear which project 

the term “contemporaneous project’ refers to (e.g., the project under review or a previous project 

that resulted in a creditable emission increase or decrease during the “contemporaneous” period 

as defined in subsection (2)). EPA’s definition of NEI provides that a source owner/operator may 

take into account those increases or decreases in actual emissions that are “contemporaneous 

with the increase from the particular change,” i.e., that occur “within a reasonable period (to be 

specified by the State) before the date that the increase from the particular change occurs.” 40 

CFR 51.166(b)(3)(ii) (emphasis added). This definition does not call for any assessment of

actual emissions after a contemporaneous project; only those increases and decreases that are 

“contemporaneous” with the project under review may be considered. 

Additionally, subparagraph (1)(C)(ii) allows for actual emissions to be determined based on 

projected actual emissions (PAE) if the Control Officer determines that there is no sufficiently 
23

representative time period to determine “actual emissions after a contemporaneous project.”

EPA’s regulations do not allow for the use of PAE in the calculation of NEI. 40 CFR 51.166(b)(3).

We propose to disapprove this provision. This limited disapproval, if finalized, would require 

Clark to remove paragraphs (1)(C)(i), (ii) and (iii) from the definition of NEI in subsection 

12.2.2(ii), and to submit the revised rule to EPA for approval into the Clark County portion of the 

Nevada SIP.

We note that paragraph (6) of subsection 12.2.2(ii) mirrors EPA’s provision in 40 CFR 

51.166(b)(3)(vii) for replacement units that require shakedown except that, in addition to any 

“replacement unit” (as defined in 40 CFR 51.166(b)(32)), paragraph (6) provides that any other 

“new emission unit that replaces an existing emissions unit and that requires shakedown” is also 

allowed a reasonable shakedown period before the emission increase is considered to have 

occurred. This is acceptable.

Major modification

The definition of the term “major modification” in subsection 12.2.2(dd) states (in subparagraph 

(4)) that “[t]he fugitive emissions of a major stationary source shall not be included in 

determining, for any of the purposes of Section 12.2, whether a particular physical change or 

change in the method of operation is a major modification unless the major stationary source is a 

categorical stationary source or belongs to any other stationary source category which, as of 

August 7, 1980, is being regulated under Section 111 or 112 of the Act.” Although this language 

is consistent with the text of 40 CFR 51.166(b)(2)(v) as of July 1, 2010, EPA has administratively 

stayed this paragraph indefinitely, effective March 30, 2011 (76 FR 17548) (final rule effectuating 

and extending stay of the final rule entitled "Prevention of Significant Deterioration (PSD) and 

Nonattainment New Source Review (NSR): Reconsideration of Inclusion of Fugitive Emissions"

(“Fugitive Emissions Rule”) published December 19, 2008). The effect of this administrative stay 

was to revert the treatment of fugitive emissions in applicability determinations to the approach 

that applied prior to the Fugitive Emissions Rule, thus requiring that fugitive emissions be 

included in major modification applicability determinations for all source categories. 76 FR at 

17550, 17551. The definition of “major modification” in subsection 12.2.2(dd) is not consistent 

with this approach to the treatment of fugitive emissions in applicability determinations. We 

therefore propose to disapprove this definition. This limited disapproval, if finalized, would 

require Clark to revise Section 12.2 to require that fugitive emissions be included in major 

modification applicability determinations for all source categories.

Prevention of Significant Deterioration (PSD) Permit

The definition of this term in subsection 12.2.2(ll) is consistent with the definition of the term in

EPA’s nonattainment NSR regulations in 40 CFR 51.165(a)(1)(xli), rather than the PSD definition

in section 51.166(b)(42). As such, it omits the last sentence contained in EPA’s definition of the 

term “Prevention of Significant Deterioration (PSD) Program” in 40 CFR 51.166(b)(42). Clark’s 

definition of “Prevention of Significant Deterioration (PSD) Permit” in subsection 12.2.2(ll) should 

be revised to match the applicable PSD definition in 40 CFR 51.166, which includes a sentence 

reading “Any such permit is a major NSR permit.” We are not citing this as a deficiency but 
24

recommend that Clark revise subsection 12.2.2(ll) to include this additional language in the 

definition of “Prevention of Significant Deterioration (PSD) Permit.”

Projected actual emissions

The definition of the term “Projected Actual Emissions” (PAE) in subsection 12.2.2(nn) varies 

slightly from EPA’s definition in 40 CFR 51.166(b)(40). Although EPA’s definition of PAE requires 

the inclusion of emissions associated with malfunctions (see 40 CFR 51.166(b)(40)(ii)(b)), 

paragraph (1)(C) of subsection 12.2.2(nn) requires exclusion of “emissions from a shutdown 

associated with a malfunction.” As discussed above with regard to the definition of BAE, 

however, this is permissible because BAE also must exclude “emissions from a shutdown 

associated with a malfunction.” EPA believes this approach will result in equivalent or higher 

estimates of emission increases for modified emission units, since the emissions associated with 

future malfunctions should generally be equal to or less than malfunction-related emissions in a 

baseline year. Therefore, the omission of the requirement to include malfunction-related 

emissions in PAE is acceptable.

B. EPA’s Revisions to Definitions in 40 CFR 51.166 Since DAQ’s Adoption of Section 12.2

Subsequent to Clark’s adoption of Section 12.2, EPA revised the definition of 

“Regulated NSR Pollutant” in 40 CFR 51.166(b)(49) through the following final rules:

(1) “Implementation of the New Source Review (NSR) Program for Particulate Matter 

Less Than 2.5 Micrometers (PM2.5),” dated May 16, 2008 (73 FR 28321),

(2) “Prevention of Significant Deterioration and Title V Greenhouse Gas Tailoring 

Rule,” dated June 3, 2010 (75 FR 31514), and

(3) “Requirements for Preparation, Adoption, and Submittal of Implementation 

Plans,” dated April 6, 2011 (76 FR 18870) (CFR correction notice).

Discussion: The revised elements of EPA’s definition of “Regulated NSR Pollutant” now read as 

follows (with new language that subsection 12.2.2(pp) does not satisfy shown in underline): 

Regulated NSR pollutant (51.166 (b)(49)(i) and (vi) only):

(i) Any pollutant for which a national ambient air quality standard has been promulgated and 

any pollutant identified under this paragraph (b)(49)(i) as a constituent or precursor to such 

pollutant. Precursors identified by the Administrator for purposes of NSR are the following: 

(a) Volatile organic compounds and nitrogen oxides are precursors to ozone in all 

attainment and unclassifiable areas. 

(b) Sulfur dioxide is a precursor to PM2.5 in all attainment and unclassifiable areas. 

(c) Nitrogen oxides are presumed to be precursors to PM2.5 in all attainment and 

unclassifiable areas, unless the State demonstrates to the Administrator's satisfaction or 

EPA demonstrates that emissions of nitrogen oxides from sources in a specific area are 

not a significant contributor to that area's ambient PM2.5 concentrations. 
25

(d) Volatile organic compounds are presumed not to be precursors to PM2.5 in any 

attainment or unclassifiable area, unless the State demonstrates to the Administrator's 

satisfaction or EPA demonstrates that emissions of volatile organic compounds from 

sources in a specific area are a significant contributor to that area's ambient PM2.5

concentrations. 

(vi) Particulate matter (PM) emissions, PM2.5 emissions, and PM10 emissions shall include 

gaseous emissions from a source or activity which condense to form particulate matter at 

ambient temperatures. On or after January 1, 2011, such condensable particulate matter 

shall be accounted for in applicability determinations and in establishing emissions 

limitations for PM, PM2.5 and PM10 in PSD permits. Compliance with emissions limitations for 

PM, PM2.5 and PM10 issued prior to this date shall not be based on condensable particular 

matter unless required by the terms and conditions of the permit or the applicable 

implementation plan. Applicability determinations made prior to this date without accounting 

for condensable particular matter shall not be considered in violation of this section unless 

the applicable implementation plan required condensable particular matter to be included. 

[Note: On March 16, 2012, EPA published a proposed rule entitled “Amendment to the 

Definition of ‘Regulated NSR pollutant’ Concerning Condensable Particulate Matter” (77 FR 

15656), which may upon finalization require additional revisions to Clark’s definition of 

“Regulated NSR pollutant.”]

We therefore propose to disapprove Clark’s definition of “regulated NSR pollutant” in subsection 

12.2.2(pp). This limited disapproval, if finalized, would require Clark to revise the definition of 

“Regulated NSR Pollutant” contained in Section 12.2 to include the additional language in 40 

CFR section 51.166(b)(49)(i) regarding precursors to ozone and PM2.5 and section 

51.166(b)(49)(vi) regarding condensable PM.

In addition, on October 20, 2010, EPA published a final rule entitled “Prevention of 

Significant Deterioration (PSD) for Particulate Matter Less Than 2.5 Micrometers 

(PM2.5)–Increments, Significant Impact Levels (SILs) and Significant Monitoring 

Concentration (SMC)” (75 FR 64864), which, among other things, established PM2.5

increments as minimum program elements for all State PSD programs. We are not 

identifying the absence of these requirements in Section 12.2 as a deficiency at this 

time but note that Clark is required to submit, no later than July 20, 2012, a SIP revision 

that incorporates the final PM2.5 increments or alternative measures that can be 

demonstrated to EPA's satisfaction to provide an equivalent level of protection as the 

PM2.5 increments. See 75 FR 64864, 64898. The relevant definitions in 40 CFR 

51.166(b) now read as follows (with new language shown in underline):

Baseline area (40 CFR 51.166(b)(15))

(i) Baseline area means any intrastate area (and every part thereof) designated as 

attainment or unclassifiable under 40 CFR Part 81 section 107(d)(1)(A)(ii) or (iii) of the Act in 

which the major source or major modification establishing the minor source baseline date 

would construct or would have an air quality impact equal to or greater than one (1) 

microgram per cubic meter (annual average) of the pollutant for which the minor source 
26

baseline date has been established; for the pollutant for which the baseline date is 

established, as follows: Equal to or greater than 1 μg/m3 (annual average) for SO2, NO2, or 

PM10; or equal or greater than 0.3 μg/m3 (annual average) for PM2.5.

(ii) Area redesignations under40 CFR Part 81 section 107(d)(1)(A)(ii) or (iii) of the Act cannot 

intersect or be smaller than the area of impact of any major stationary source or major 

modification which:

Major source baseline date (51.166 (b)(14)(i) only)

( a ) In the case of particulate matter PM10 and sulfur dioxide, January 6, 1975; and

( b ) In the case of nitrogen dioxide, February 8, 1988; and

( c ) In the case of PM2.5,October 20, 2010. 

Minor source baseline date (51.166 (b)(14)(iii)(a) only)

(a) The area in which the proposed source or modification would construct is designated as 

attainment or unclassifiable under section 107(d)(1)(A)(ii) or (iii) of the Act for the pollutant 

on the date of its complete application under Section 12.2 of the AQRs; and

C. Additional terms in Section 12.2

The following terms are used in Section 12.2 but are not specifically defined in EPA’s

regulations in 40 CFR 51.166. EPA has reviewed these terms and believes that they

strengthen the program by providing clear definitions for terms used in Section 12.2.

These terms include the following: Basic design parameter, Categorical stationary source, 

Complete, Shutdown and Startup.

3. Provisions which establish the maximum allowable ambient air increments and ambient air 

ceilings as set forth in 40 CFR 51.166(c) and (d), for any designated attainment or 

unclassifiable area.

Discussion: Subsections 12.2.3 (Ambient Air Increments) and 12.2.4 (Ambient Air Ceilings), specify 

maximum allowable ambient air increments and ambient air ceilings for PM10, SO2, and NO2

consistent with EPA’s ambient air increments and ambient air ceilings for these pollutants. Section 

12.2 does not include ambient air increments for PM2.5 but as noted above, PSD SIP revisions 

establishing PM2.5 increments are not due until July 20, 2012. The provisions of subsection 12.2.3 

and subsection 12.2.4 therefore satisfy current requirements but will soon need to be revised to 

address the required increments for PM2.5. See 75 FR 64864 (October 20, 2010).

4. Provisions concerning the initial designation of all attainment areas as Class I, II, or III, as 

listed in 40 CFR 51.166(e) and (g).

Discussion: Section 12.2, subsections 12.2.5 and 12.2.6 contains provisions concerning designation 

of areas consistent with 40 CFR 51.166(e) and (g). Because there is no federally required Class I 

area in Clark County and all other areas are designated as Class II (see subsection 12.2.6.1), 

Section 12.2 meets this requirement.
27

5. Provisions, pursuant to 40 CFR 51.166(h), to assure that the degree of emission limitation 

required of any source for control of any air pollutant must not be affected by so much of 

any source's stack height that exceeds good engineering practice.

Discussion: Section 12.2, subsection 12.2.7 (Stack Heights), contains provisions concerning stack 

height and associated emission limitations. This provision satisfies the regulatory requirement.

6. Provisions, pursuant to 40 CFR 51.166(i), which allow for specified exemptions from the 

PSD program at the State’s election.

Discussion: Section 12.2, subsection 12.2.8 (Exemptions), contains specific exemptions for nonprofit 

health or nonprofit educational institutions, and for portable stationary sources in specific 

circumstances; both of which are consistent with the provisions of 40 CFR 51.166(i).

7. Provisions, pursuant to 40 CFR 51.166(j), which require BACT, determined on a 

case-by-case basis, for a new major source or major modification.

Discussion: Section 12.2 requires BACT for all new major sources or major modifications.

Subsection 12.2.9.1 requires a new major stationary source to apply BACT for each regulated NSR 

pollutant that it would have the potential to emit in significant amounts. For major modifications, 

subsection 12.2.9.2 requires BACT for each regulated NSR pollutant for which there is a significant 

net emissions increase at the stationary source.

PSD review, including control technology review, also applies to certain non-criteria pollutants such 

as particulate matter, green house gases (GHG), fluorides (except hydrogen fluoride), sulfuric acid 

mist, hydrogen sulfide, total reduced sulfur, reduced sulfur compounds, municipal waste combustor 

organics, metals, and acid gases, municipal solid waste landfill emissions, and pollutants regulated 

under title VI of the Act (e.g., CFCs and HCFCs). New or modified sources of such non-criteria 

pollutants are covered by the definitions of the terms “regulated NSR pollutant” and “significant” in 

subsection 12.2.2, which identify each of these pollutants and establish significant net emissions 

increase thresholds that match the federal thresholds. These provisions satisfy the regulatory 

requirements. 

8. Provisions, pursuant to 40 CFR 51.166(k), which address the requirements for a source 

impact analysis.

Discussion: Section 12.2, subsection 12.2.10 (Source Impact Analysis), contains all of the specified 

provisions to address source impact analysis requirements. This provision satisfies the regulatory 

requirement.

9. Provisions pursuant to 40 CFR 51.166(l) requiring air quality modeling consistent with the 

applicable requirements of appendix W of 40 CFR part 51 (“Guideline on Air Quality 

Models”), and provisions pursuant to 40 CFR 51.166(m) to assure that a major source or 

major modification will perform an air quality analysis, including pre-application air 
28

monitoring for any pollutant for which the net emissions increase of the source or 

modification is significant, and post-construction monitoring as necessary to determine the 

effect the emissions may have, or are having, on air quality in any area.

Discussion: With respect to both criteria and non-criteria air pollutants, subsection 12.2.12, Air 

Quality Analysis, satisfies the requirement for an air quality analysis including pre-application and 

post-construction monitoring requirements. Subsection 12.2.11, Air Quality Models, requires that all 

estimates of ambient concentrations be based on applicable air quality models, databases, and other 

requirements specified in 40 CFR Part 51, Appendix W (“Guideline on Air Quality Models”), except 

where EPA approves a modification or substitution to such a model following public notice and 

opportunity for comment. These provisions satisfy the regulatory requirements. 

10. Provisions, pursuant to 40 CFR 51.166(n), requiring the submission of all information

necessary to perform any analysis or make any determination required under the PSD 

program. 

Discussion: Section 12.2, subsection 12.2.13 (Source Information), contains all of the specified 

provisions to require that permit applicants submit all information necessary to perform any analysis 

or make any determination required under Section 12.2. This provision satisfies the regulatory 

requirement.

11. Provisions, pursuant to 40 CFR 51.166(o), to assure that the owner of operator of a major 

source or major modification will perform additional impact analyses of the impairment to 

visibility, soils, and vegetation and the air quality impact projected for the area as a result 

of general commercial, residential, industrial and other growth associated with the source 

or modification.

Discussion: Subsection 12.2.14 (Additional Impact Analyses), includes the provisions necessary to 

assure that the required additional impact analyses are performed.

12. Provisions to assure protection of air quality related values (including visibility) in Class I 

areas pursuant to 40 CFR 51.166(p).

Discussion: The requirements for protection of air quality related values (AQRV) (including visibility) 

are found in section 165(d)(2) of the Act, 40 CFR 51.166(p) and 40 CFR 51.307. These requirements 

include notification of a permit application to the Federal land manager (FLM) and the Federal official 

charged with direct responsibility for management of any lands within a Class I area which may be 

affected by emissions from a proposed major source or major modification. Also, the PSD program 

must provide a mechanism whereby an FLM or other Federal official may present to the permitting 

authority, after the reviewing authority’s preliminary determination, a demonstration that the 

emissions from the proposed source or modification would have an adverse impact on the AQRV 

(including visibility) of any Federal mandatory Class I lands, notwithstanding that the change in air 

quality resulting from emissions from such source or modification would not cause or contribute to 

concentrations which would exceed the maximum allowable increases for a Class I area. If the 
29

reviewing authority concurs with such demonstration, the reviewing authority must not issue the 

permit.

Clark County lies within the proximity (i.e., within 100 kilometers) of Grand Canyon National Park, a 

Federal Mandatory Class I area. Zion National Park, another Federal Mandatory Class I area, lies 

just beyond the 100 kilometer distance. Clark Section 12.2, subsection 12.2.15(Additional 

Requirements for Sources Impacting Class I Areas) requires additional Class I area analyses under 

certain circumstances and provides a framework for coordination between Clark and the FLM (or 

other relevant Federal official) concerning potential impacts on Class I areas. These provisions meet 

the regulatory requirements.

Subsection 12.2.15.2 requires the Control Officer to consult with the FLM on a proposed major 

stationary source or major modification that may impact visibility in any Class I Area, in accordance 

with 40 CFR 51.307. This is acceptable to meet the visibility element of this requirement.

13. Provisions to assure agency and public participation under 40 CFR sections 51.166(p)(1) 

and 51.166(q).

Discussion: Prior to public review: Section 165(d)(1) of the Act, which is also set forth at 40 CFR 

51.166(p)(1), requires the PSD reviewing authority to transmit to EPA a copy of each permit 

application relating to a major new source or major modification and to provide notice to EPA of every 

action related to the consideration of such permit. Section 12.2, subsection 12.2.15.1 (Notice to EPA) 

requires the Control Officer to “transmit to the Administrator a copy of each permit application relating 

to a major stationary source or major modification, and provide notice to the Administrator of every 

action related to the consideration of such permit.” This provides for the necessary coordination with 

EPA. Because NDEP shares PSD increment-tracking responsibility with Clark for baseline areas 

inside Clark County, we recommend that Clark revise subsection 12.2.15.1 at the earliest possible 

opportunity to provide for copies of permit applications to also be sent to NDEP. NDEP coordination 

should also occur prior to public review to ensure proper analysis of increment consumption. We do 

not consider this oversight to be an approvability issue.

Discussion: Public review: Section 12.2, subsection 12.2.16 (Public Participation), complies with the 

public participation requirements in 40 CFR 51.166(q).

14. Provisions, pursuant to 40 CFR 51.166(r), which address source obligation requirements.

Discussion: Section 12.2, subsection 12.2.17 (Source Obligation), contains all of the specified 

provisions to ensure an applicant will meet all of the required source obligation requirements. This 

provision satisfies the regulatory requirement.

15. Provisions, pursuant to 40 CFR 51.166(w), which address Actuals PALs.

Discussion: Section 12.2, subsection 12.2.19 (Plantwide Applicability Limits (PALs)) closely mirrors 

all of the paragraphs contained in 40 CFR 51.166(w), with one exception. 40 CFR 51.166(w)(10)(v)

states that “[i]f the compliance date for a State or Federal requirement that applies to the PAL source 
30

occurs during the PAL effective period, and if the reviewing authority has not already adjusted for 

such requirement, the PAL shall be adjusted at the time of PAL permit renewal or title V permit 

renewal, whichever occurs first” (emphasis added). Subsection 12.2.19.10(e) states that “[i]f the 

compliance date for a federal or state requirement that applies to the PAL source occurs during the 

PAL effective period, and if the Control Officer has not already adjusted for such requirement, the 

PAL shall be adjusted at the time the affected Part 70 Operating Permit is renewed” (emphasis 

added). Although Part 70 permits are generally renewed more frequently than PAL permits, at any 

given time it is possible that the expiration date for a PAL permit will occur before the expiration date 

for a Part 70 permit. We propose to disapprove this provision because it is not consistent with EPA’s 

requirements for PALS in 40 CFR 51.166(w)(10)(v). This limited disapproval, if finalized, would 

require Clark to revise subsection 12.2.19.10(e) to require adjustment of PALs to address additional 

compliance requirements at the time of PAL permit renewal or title V permit renewal, whichever 

occurs first, consistent with 40 CFR 51.166(w)(10)(v).

Additionally, EPA recommends that Clark revise subsection 12.2.19.2(a) to clarify the applicable 

definitions. Subsection 12.2.19.2(a) currently states that the listed definitions apply and that “[w]hen 

a term is not defined in these paragraphs, it shall have the meaning given in Section 0, Section 12.4 

or the Act.” To the extent that Clark intended for the definitions provided in Section 12.2 (subsection 

12.2.2) to apply before any of the other cited provisions, we recommend clarifying the provision 

accordingly.

Section 12.3 – Permit Requirements for Major Sources in Nonattainment Areas

Clark County is currently designated nonattainment for the PM10 NAAQS and the 1997 8-hour 

ozone NAAQS. 40 CFR 81.329. The Nevada State Environmental Commission (SEC), the 

administrative body responsible for the air quality regulations implemented by NDEP, has not 

adopted a preconstruction permit program that complies with part D of the Act (i.e., 

Nonattainment NSR) for the nonattainment areas within Clark County. Generally, because NDEP 

has jurisdiction over a particular category of stationary sources in the ozone and PM10

nonattainment areas within Clark County (e.g., Las Vegas, El Dorado and Ivanpah Valleys), the 

State is required to adopt and submit a Nonattainment NSR program for major new or modified 

sources within the applicable source category in these nonattainment areas. With respect to the 

PM10 nonattainment area in Clark County (the Las Vegas planning area, hydrographic area 212) 

and certain portions of the Clark County ozone nonattainment area (i.e., the Las Vegas Valley

(hydrographic area 212), El Dorado Valley (hydrographic area 167), Ivanpah Valley 

(hydrographic areas 164a and 164b), and the city limits of Boulder City), EPA is not requiring the 

State to submit Nonattainment NSR rules because the Nevada SEC adopted a regulation [Nevada 

Administrative Code (NAC) section 445B.22083] that prohibits the construction of new power 

plants or major modifications to existing power plants under State jurisdiction within these areas.

9

EPA approved NAC section 445B.22083 into the Nevada SIP as part of our September 7, 2004

rulemaking. 69 FR 54006, 54019 (September 7, 2004). This action resolved the regulatory gap that 

would otherwise exist in connection with NSR for PM10 sources under NDEP jurisdiction within 

 9 This construction prohibition applies within the following areas, with limited exceptions: (a) Las Vegas Valley, 

Hydrographic Area 212; (b) El Dorado Valley, Hydrographic Area 167; (c) Ivanpah Valley, Hydrographic Areas 164 

a and 164 b; and (d) The city limits of Boulder City. See NAC 445B.22083.
31

the Las Vegas planning area, and for NOx and VOC sources under NDEP jurisdiction within those 

portions of the Clark County ozone nonattainment area that are covered by NAC section 

445B.22083.

Several hydrographic areas within the Clark County ozone nonattainment area outside of Las 

Vegas Valley, however, are not covered by NAC section 445B.22083: specifically, hydrographic 

areas 165, 166, 213, 214, and 216-218. See 40 CFR 81.329.10 Although EPA has recently 

determined that Clark County is attaining the 1997 8-hour ozone NAAQS (76 FR 17343), this 

determination did not affect NSR obligations for that standard. See 77 FR 28424, at Tables 2 and 3 

(May 14, 2012). Thus, with respect to sources under NDEP jurisdiction (i.e., major new or 

modified plants which generate electricity by using steam produced by the burning of fossil fuel) 

within these portions of the Clark County ozone nonattainment area, NDEP remains obligated to 

implement Nonattainment NSR requirements for the 1997 8-hour ozone NAAQS. Pursuant to 

EPA’s recent classification of the area as “marginal” nonattainment for the 1997 8-hour ozone 

standard effective June 13, 2012 (77 FR 28424, May 14, 2012), NDEP is now obligated to submit 

NSR SIP revisions for Clark County meeting the applicable requirements of subpart 2 of part D, 

title I of the Act, including an offset ratio of 1.1 to 1 for NOx and VOC (see CAA 182(a)(4)) no 

later than June 13, 2013. Alternatively, NDEP may revise NAC section 445B.22083 to extend its 

construction prohibitions to these hydrographic areas and submit this revised rule to EPA for 

approval into the SIP. 

The Act requires all States with nonattainment areas to submit a NSR program that contains the 

following nonattainment NSR provisions. To demonstrate that Clark has met each provision, EPA 

identifies the section(s) of the submitted NSR rules which satisfy the listed requirement. Where 

necessary, a detailed discussion accompanies deficiencies in the rules that have been identified 

through this review. 

1. Provisions to assure that calculation of emissions offsets, as required by section 

173(a)(1)(A), are based on the same emissions baseline used in the demonstration of 

reasonable further progress.

Discussion: The requirements for offsets in Section 12.3, subsection 12.3.6 do not contain a 

provision to assure that emission offset calculations are based on the same emissions baseline used 

in the demonstration of reasonable further progress (RFP) for the relevant NAAQS pollutant, where 

applicable. We therefore propose to disapprove Section 12.3 with respect the requirement in CAA 

section 173(a)(1)(A) regarding baseline emissions in the calculation of offsets. This limited 

disapproval, if finalized, would require Clark to revise Section 12.3 to include a provision requiring 

that emissions offsets calculations be based on the same emissions baseline used in the 

demonstration of reasonable further progress for the relevant NAAQS pollutant (where applicable), 

and to meet the additional requirements related to offset calculations in 40 CFR 51.165(a)(3). We 

note that the emissions inventories supporting the Las Vegas Valley PM10 attainment and RFP 

 10 The ozone nonattainment within Clark County is defined in 40 CFR part 81 as “[t]hat portion of Clark County 

that lies in hydrographic areas 164A, 164B, 165, 166, 167, 212, 213, 214, 216, 217, and 218 but excluding the 

Moapa River Indian Reservation and the Fort Mojave Indian Reservation.”
32

demonstration and the Clark County ozone redesignation request and maintenance plan are based 

on actual emissions, and that Clark may meet the requirement in CAA section 173(a)(1)(A) by 

demonstrating that all PM10, NOx, and VOC ERCs used to satisfy offset requirements under Section 

12.3 must, by definition, be calculated based on reductions in actual emissions, consistent with these 

plans submissions. As currently drafted, however, the criteria in Section 12.3 for evaluation and 

approval of ERCs are not adequate to meet this requirement, as discussed in item #3 below.

Regarding the amount of offsets that is necessary to show noninterference with RFP, EPA presumes 

that so long as a new source obtains offsets in an amount equal to or greater than the amount 

specified in the applicable offset ratio (or, where the statute does not specify an offset ratio, in an 

amount equal to or greater than 1:1), the new source will not interfere with RFP. Table 12.3-1 in 

Section 12.3, subsection 12.3.6.5, establishes a 1:1 offset ratio for NOx and VOC in any area that is 

“nonattainment without designation” and a 1:1 offset ratio for CO and PM10 in any “serious 

nonattainment area.” The Act does not specify an offset ratio for either PM10 or CO, and thus Clark’s 

offset ratio of 1:1 for these pollutants is acceptable. As to CO, because EPA has redesignated Clark 

County as attainment for the CO NAAQS (75 FR 59090, September 27, 2010), neither the CO offset 

ratio nor any other portion of section 12.3 is applicable to any source for CO purposes at this time.

With respect to ozone precursors (NOx and VOC), because Clark County was not initially classified 

under subpart 2 of part D, title I of the Act for the 1997 8-hour ozone NAAQS, Clark’s offset ratio of 

1:1 for NOx and VOC is currently acceptable for purposes of meeting the NSR requirements in 

subpart 1 of part D, title I of the Act for this standard. On April 27, 2012, however, EPA finalized its 

classification rulemaking for all former subpart 1 ozone nonattainment areas nationwide, and as part 

of that rulemaking we classified the Clark County ozone nonattainment area as “marginal” 

nonattainment for the 1997 8-hour ozone standard. 77 FR 28424 (May 14, 2012). Accordingly, the 

State is now obligated to submit NSR SIP revisions meeting the applicable requirements of subpart 2 

of part D, title I of the Act, including an offset ratio of 1.1 to 1 for NOx and VOC (see CAA 182(a)(4)),

no later than June 13, 2013.

We also note that Clark’s use of the phrase “nonattainment without designation” in Table 12.3-1 is 

confusing, as any nonattainment area is, by definition, designated. As part of its rulemaking to 

incorporate the 1.1 to 1 offset ratio required pursuant to EPA’s subpart 2 classification of the Las 

Vegas Valley area for the 1997 8-hour ozone NAAQS, Clark should revise Table 12.3-1 to clarify that 

the revised offset ratio for NOx and VOC applies throughout the “marginal” ozone nonattainment area

in Clark County.

2. Provisions to assure, pursuant to section 173(c)(1), that any emissions offsets obtained in 

conjunction with the issuance of a permit to a new or modified source must be enforceable 

by the time of issuance of the permit, and in effect by the time the new or modified source 

commences operation. 

Discussion: Section 12.3, subsection 12.3.6.4(a) states that “Internal emission reductions used to 

satisfy an offset requirement must be federally enforceable at the time of issuance of the Authority to 

Construct Permit containing the offset requirements.” Subsection 12.3.6.4(b) states that “...the 

decrease in actual emissions used to generate ERCs or internal emission reductions must occur by 

no later than the commencement of operation of the new or modified major stationary source,” with a 
33

limited exception for a new facility that replaces a facility being shut down to provide offsets.

Consistent with EPA’s definition of “net emissions increase” in 40 CFR 51.165(a)(1)(vi)(A), under 

subsection 12.3.6.4(c) Clark may allow up to 180 calendar days for “shakedown or commissioning”

of such a new facility before the existing facility must cease operation. These provisions adequately 

address the requirements in CAA 173(c)(1) related to the point in time at which offsets must become 

enforceable and reductions must occur. As discussed below, however, other provisions in Section 

12.3 render the program deficient with respect to the requirements for offsets in CAA 173(c)(1).

3. Provisions to assure that emissions increases from new or modified major stationary 

sources are offset by real reductions in actual emissions as required by section 173(c)(1).

Discussion: Section 12.3, subsection 12.3.6.6(a) states that “Emission reductions used to satisfy 

offset requirements must be real, surplus, permanent, quantifiable, and federally enforceable.” This 

provision is acceptable, but several related provisions in subsections 12.3.6.2 and 12.3.6.7 render 

the program in Section 12.3 deficient with respect to the offset requirements of CAA 173(c)(1). 

Specifically, Section 12.3 does not contain adequate criteria for determining whether certain 

emission reductions may qualify for use as offsets, as explained below.

Subsection 12.3.6.1 states that the determination whether an applicant has surrendered sufficient 

offsets prior to commencing operation requires, at minimum, compliance with the offset requirements 

in subsection 12.3.6.2. Subsection 12.3.6.2 provides that “[p]ollutant-specific emissions shall be 

offset with federally enforceable ERCs or with internal emission reductions” in accordance with 

specified criteria, but these criteria include references to criteria in a separate rule called Section 

12.7. Similarly, subsection 12.3.6.7 provides necessary geographic limitations on emissions 

reductions used to satisfy offsets requirements but provides that certain emission reductions that do 

not occur at the “same major stationary source at which the increase in emissions occurs” may 

nonetheless qualify as “internal emission reductions” if such reductions “meet the requirements for 

ERCs prescribed by Section 12.7.” Because Section 12.7 is neither approved into the SIP nor 

included in the NSR SIP submittal, EPA cannot approve provisions that allow sources to comply with 

criteria specified in Section 12.7 in lieu of appropriate criteria in Section 12.3. We therefore propose 

to disapprove Section 12.3 with respect to the offset requirements in CAA section 173(c)(1). This 

limited disapproval, if finalized, would require Clark to revise Section 12.3 to include criteria (or 

reference appropriate criteria in a separate, SIP-approved rule) that will assure that emissions 

increases from new or modified major stationary sources are offset by real reductions in actual 

emissions, as required by CAA 173(c)(1). 

In addition, subsection 12.3.6.3 allows for interpollutant trades between VOC and NOx emission 

reductions for purposes of satisfying offset requirements for ozone, and interpollutant trades among 

PM2.5, SO2 and NOx emission reductions for purpose of satisfying offset requirements for PM2.5. The 

provision for trading between VOC and NOx ERCs is not acceptable without a demonstration 

supported by air quality modeling that such trades will result in a net air quality benefit in the 

nonattainment area, or a requirement to submit any proposed interpollutant trade for offset purposes, 

on a case by case basis, to EPA for review and concurrence prior to issuance of the permit. See 

"Improving Air Quality with Economic Incentive Programs," January 2001, at 16.9 and 16.14. The 

provisions for PM2.5 precursor trades are not consistent with 40 CFR 51.165(a)(11), which requires 
34

that emissions offsets obtained “shall be for the same regulated NSR pollutant unless interprecursor 

offsetting is permitted for a particular pollutant as specified in this paragraph” and provides that 

interpollutant trades between PM2.5 and certain precursors are allowed only where those PM2.5 

precursors are specifically identified in the approved definition of “regulated NSR pollutant” and 

where “such offsets comply with the interprecursor trading hierarchy and ratio established in the 

approved plan for a particular nonattainment area.” Although Section 12.3 does not currently apply to 

PM2.5 sources because Clark County is designated attainment/unclassifiable for the PM2.5 NAAQS, 

we nonetheless propose to disapprove this provision because it is contrary to EPA requirements for 

both ozone and PM2.5 purposes. This limited disapproval, if finalized, would require Clark to revise 

Section 12.3 to prohibit interpollutant trades except where interprecursor offsetting is permitted for a 

particular pollutant consistent with the requirements of 40 CFR 51.165(a)(11) and EPA policy on 

interpollutant trades.

4. Provisions, pursuant to section 173(c)(2), to prevent emissions reductions otherwise 

required by the Act from being credited for purposes of satisfying the part D offset 

requirements.

Discussion: Section 12.3, subsection 12.3.6.6(a) states that “Emission reductions used to satisfy 

offset requirements must be real, surplus, permanent, quantifiable, and federally enforceable.” 

(Emphasis added)

“Surplus” is defined in 12.3.2 as “...an emission reduction that has not been relied on in any air 

quality program related to any SIP, that is not a Nevada SIP requirement, that is not a requirement of 

a state air quality program that has been adopted but is not in the Nevada SIP, is not credited in any 

federal reasonable further progress or other milestone demonstration, is not a requirement of a 

consent decree, is not a requirement of a federal rule that focuses on reducing criteria air pollutants 

or their precursors, and has not already been credited in any other air quality program. The purpose 

of requiring that emissions offsets be surplus is to prohibit double-counting of emission reductions.”

This definition is not adequate to ensure that emission reductions required by standards promulgated 

under CAA section 111 (New Source Performance Standards) or under CAA section 112 (National 

Emission Standards for Hazardous Air Pollutants) are not credited for purposes of satisfying part D 

offset requirements. We therefore propose to disapprove this provision. This limited disapproval, if 

finalized, would require Clark to revise the definition of “surplus” in subsection 12.3.2 to ensure that 

emission reductions required by CAA section 111 or 112 standards are not treated as “surplus.”

5. Provisions, pursuant to section 173(a)(5), that, as a prerequisite to issuing any part D 

permit, require an analysis of alternative sites, sizes, production processes, and 

environmental control techniques for proposed sources that demonstrates that the benefits 

of the proposed source significantly outweigh the environmental and social costs imposed 

as a result of its location, construction, or modification.

Discussion: Section 12.3, subsection 12.3.4 states that “Prior to issuance of an Authority to Construct 

Permit for a new major stationary source or major modification subject to Section 12.3, the applicant 

shall submit an analysis of alternative sites, sizes, production processes, and environmental control 

techniques for the proposed source that demonstrates, to the satisfaction of the Control Officer, that 
35

the benefits of the proposed source significantly outweigh the environmental and social costs 

imposed as a result of its location, construction, or modification.” This provision satisfies the statutory 

requirement.

6. Definition of “stationary source” that includes certain internal combustion engines subject 

to control under State programs (i.e., those not used for transportation purposes), but 

excluding the category of “nonroad engines.” [See section 302(z) of the Act.]

Discussion: Section 12.3, subsection 12.3.2(pp) defines a stationary source as “any building, 

structure, facility, or installation which emits or may emit a regulated NSR pollutant.” This is 

consistent with EPA’s definition of the term in 40 CFR 51.165(a)(1)(i). Although this definition does 

not explicitly include internal combustion engines not used for transportation purposes or exclude

“nonroad engines,” this is acceptable provided Clark interprets its definition consistent with the 

statutory definition of “stationary source” in CAA 302(z) and no contrary definition applies.

7. Provisions, pursuant to section 173(a)(3), to assure that owners or operators of each 

proposed new or modified major stationary source demonstrate that all other major 

stationary sources under the same ownership in the State are in compliance with the Act.

Discussion: Section 12.3, subsection 12.3.3 (Statewide Compliance), states that “Prior to issuance of 

an Authority to Construct Permit for a new major stationary source or major modification subject to 

Section 12.3, the applicant shall either demonstrate that each existing major stationary source 

owned or operated by the applicant in the state of Nevada is in compliance with all applicable 

emission limitations and standards under the Act or is in compliance with an expeditious schedule 

which is federally enforceable or contained in a court decree.” This provision satisfies the statutory 

requirement.

8. Applicable definitions found in CAA section 171, and in 40 CFR 51.100 and 51.165(a)(1). 

EPA has reviewed the definitions in Sections 0 and 12.3. In most cases, the Clark 

definitions are either identical or nearly identical to the definitions in the CAA and EPA’s 

implementing regulations. In some cases, however, the Clark definitions do not track the 

language in the federal definitions as closely. We explain below in more detail our 

proposed determinations as to whether these definitions are equivalent to the federal 

definitions and, therefore, adequate to meet these requirements of a NSR program. 

A. Definitions That Differ From EPA Definitions in 40 CFR 51.165

Baseline actual emissions (BAE)

The definition of the term “Baseline Actual Emissions” (BAE) in subsection 12.3.2(c) varies in 

several respects from EPA’s definition in 40 CFR 51.165(a)(1)(xxxv). 

First, although EPA’s definition of BAE requires the inclusion of emissions associated with 

malfunctions (see 40 CFR CFR 51.165(a)(1)(xxxv)), paragraphs (1)(A) and (2)(B) of subsection 

12.3.2(c) requires the exclusion of “emissions from a shutdown associated with a malfunction.” 

However, the definition of the term “Projected Actual Emissions” in paragraph (hh)(1)(C) of 
36

subsection 12.3.2 also requires exclusion of emissions from a shutdown associated with a 

malfunction. On balance EPA believes this approach will result in equivalent or higher estimates 

of emission increases for modified emission units, since the emissions associated with future 

malfunctions should generally be estimated as the same or less when using newer modified 

equipment than malfunction-related emissions in a baseline year. Therefore, the omission of the 

requirement to include malfunction emissions in the BAE is acceptable. 

Second, paragraph (1)(C) of subsection 12.3.2(c) includes a requirement to adjust the BAE

downward to “exclude any emissions that would have exceeded an emission limitation with 

which the major stationary source must comply as of the particular date, had such major 

stationary source been required to comply with such limitations during the consecutive 24-month 

period” (emphasis added). EPA’s definition of BAE in 40 CFR 51.165 includes a similar provision 

for existing non-electric utility steam generating units (non-EUSGUs) but requires a downward 

adjustment in BAE “to exclude any emissions that would have exceeded an emission limitation 

with which the major stationary source must currently comply, had such major stationary source 

been required to comply with such limitations during the consecutive 24-month period.” 40 CFR 

51.165(a)(1)(xxxv)(B)(3). The reference in subsection 12.3.2(c)(1)(C) to an emission limitation 

that applied “as of the particular date” instead of an emission limitation with which the source 

must “currently comply” is problematic, as it is not clear which “particular date” the definition 

refers to. We propose to disapprove this provision. This limited disapproval, if finalized, would 

require Clark to revise the definition of BAE to define “particular date.”

We note, however, that to the extent that Clark intended to apply the requirement in 40 CFR 

51.165(a)(1)(xxxv)(B)(3) (which only applies to non-EUSGUs), to both EUSGUs and 

non-EUSGUs, this is acceptable as it ensures that the calculation of BAE in both cases will 

exclude emissions that exceed current emission limitations.

Major Modification

The definition of this term in subsection 12.3.2(x) requires exclusion of two specific types of 

physical or operational changes that EPA’s definition of “major modification” in 40 CFR 

51.165(a)(1)(v) does not exclude: (1) the installation or operation of a permanent Clean Coal 

Technology Demonstration Project that constitutes repowering; and (2) the reactivation of a very 

clean coal-fired electric utility steam generating unit. See Section 12.3, subsection 12.3.2(x), 

paragraph (3)(I) and (J). Although such exemptions are acceptable for purposes of PSD review, 

they are not permissible for Nonattainment NSR purposes. Specifically, section 415 of the CAA

provides that permanent clean coal technology demonstration projects that constitute 

repowering as defined in CAA section 402(12) are exempt from the PSD requirements of part C 

of title I of the Act with respect to “any pollutant the potential emissions of which will not increase 

as a result of the demonstration project.” CAA 415(b)(3); 40 CFR 51.166(b)(2)(iii)(j). Section 415 

of the Act provides that reactivation of a “very clean unit” at a coal-fired utility shall not subject the 

unit to PSD requirements where, among other things, the unit is equipped prior to shut-down with 

a continuous system of emissions control that achieves specified removal efficiencies for SO2

and particulates and is equipped with low- NOx burners prior to commencement of operations. 

CAA 415(c); 40 CFR 51.166(b)(2)(iii)(k), (b)(36). Such demonstration projects are not, however, 

exempt from the Nonattainment NSR requirements of part D of title I of the Act. Since there is no 
37

statutory basis for these exclusions in a nonattainment NSR program, we are proposing to 

disapprove the definition of “major modification” in subsection 12.3.2(x). This limited disapproval, 

if finalized, would require Clark to revise the definition of “major modification” in subsection 

12.3.2(x) to delete paragraphs (3)(I) and (J).

Additionally, the definition of the term “major modification” in subsection 12.3.2(x) also requires 

exclusion of fugitive emissions from the applicability determination unless the major stationary 

source is a categorical stationary source or belongs to any other stationary source category 

which, as of August 7, 1980, was being regulated under Section 111 or 112 of the Act.” Although 

this language is consistent with the text of 40 CFR 51.165(a)(1)(v)(G) as of July 1, 2010, EPA 

has administratively stayed this paragraph indefinitely, effective March 30, 2011 (76 FR 17548) 

(final rule effectuating and extending stay of the final rule entitled "Prevention of Significant 

Deterioration (PSD) and Nonattainment New Source Review (NSR): Reconsideration of 

Inclusion of Fugitive Emissions" (“Fugitive Emissions Rule”) published December 19, 2008). The 

effect of this administrative stay was to revert the treatment of fugitive emissions in applicability 

determinations to the approach that applied prior to the Fugitive Emissions Rule, thus requiring 

that fugitive emissions be included in major modification applicability determinations for all 

source categories. 76 FR at 17550, 17551. The definition of “major modification” in subsection 

12.3.2(x) is not consistent with this approach to the treatment of fugitive emissions in applicability 

determinations. We therefore propose to disapprove this definition. This disapproval, if finalized, 

would require Clark to revise Section 12.3 to require that fugitive emissions be included in major 

modification applicability determinations for all source categories.

Major Stationary Source

This definition contains a small typographical error, in that subsections (2)(A) and (2)(B) should 

be renumbered as paragraphs (3) and (4), since they are not subsections of Section (2). 

Regulated NSR Pollutant

The definition of “regulated NSR pollutant” in subsection 12.3.2(ii) does not satisfy current 

requirements regarding “condensable particular matter” in NSR applicability determinations. 

EPA’s definition of “regulated NSR pollutant” in 40 CFR 51.165(a)(xxxvii) includes a paragraph 

(D) stating that on or after January 1, 2011, “gaseous emissions from a source or activity which 

condense to form particulate matter at ambient temperatures” (i.e., condensable particular 

matter) must be accounted for in applicability determinations and in establishing emissions 

limitations for particulate matter (PM), PM2.5 and PM10 in NSR permits. See 73 FR 28321.We are 

proposing to disapprove this provision. This limited disapproval, if finalized, would require Clark 

to revise the definition of “regulated NSR pollutant” in subsection 12.3.2(ii) to include language 

consistent with 40 CFR 51.165(a)(xxxvii)(D).

C. Additional terms

The following terms are used in Section 12.3 but are not specifically defined in EPA’s 

regulations in 40 CFR 51.165. EPA has reviewed these terms and believes that they 

strengthen the program by providing clear definitions for terms used in Section 12.3. 
38

These terms include the following: Basic design parameter, Categorical stationary source, 

Complete, Emission Reduction Credit (ERC). In addition, we note that the definition of the term 

“Categorical stationary source - list of 28”, lists Municipal incinerators capable of charging more 

than 50 tons of refuse per day, rather than 250 tpy (see 40 CFR 51.165(a)(1)(iv)(C)(8)). We 

recommend this typographical error be fixed the next time the rule is open for revision.

9. Provisions, pursuant to 40 CFR 51.161 that require opportunity for public comment, as 

well as the consideration of any comments received during this period in the final permit 

determination. These provisions must also ensure the availability of all information 

relevant to the proposed permit during the comment period, and allow for a public hearing 

upon request.

Discussion: Section 12.3, subsection 12.3.8 (Public Participation), requires that ATC issuance be 

“subject to the public participation requirements in subsection 12.2.16.” subsection 12.2.16 (Public 

Participation) contains detailed requirements for public procedures that satisfy the criteria specified 

in 51.161. These provisions satisfy the regulatory requirement.

10. For districts which have submitted a minor source NSR permitting program: provisions, 

pursuant to 40 CFR 51, sections 160 through 164, which contain substantive requirements 

for minor sources. These requirements include public notice, opportunity for–and 

consideration of–public comment, and the demonstration that a minor source will not 

contribute to a violation of any national standard or the area’s control strategy for 

attainment.

Discussion: Section 12.1 contains substantive requirements for minor sources, adequate public 

notice requirements for all such sources that may significantly affect air quality, and procedures for 

demonstrating that a minor source will not contribute to a violation of any NAAQS or control strategy

for attainment. See, e.g., subsection 12.1.5.3 (Public Participation); subsection 12.1.4.1(c)(1) (Terms 

and Conditions); subsection 12.1.3.6(a)(3) (Application Contents); subsection 12.1.5.1(a)(4) (Action 

on Application), and subsection 12.1.6 (Revisions to an Existing Minor Source Permit); see also our

evaluation of Section 12.1 above. As such, Clark’s program for public participation covers the larger 

proposed minor sources and modifications and thereby ensures that minor sources will not 

contribute in any significant way to a violation of any NAAQS or the area’s control strategy for 

attainment.

11. Provisions, pursuant to 40 CFR 51.118(a), to assure that the degree of emission limitation 

required of any source for control of any air pollutant must not be affected by so much of 

any source's stack height that exceeds good engineering practice.

Discussion: Clark’s PSD program in Section 12.2 contains a provision satisfying this requirement (in 

subsection 12.2.7.3), but the NSR program in Section 12.3 does not contain a corresponding 

requirement. We propose to disapprove Section 12.3 with respect to this requirement. This limited 

disapproval, if finalized, would require Clark to add a provision to Section 12.3 or Section 12.4 that 

satisfies the requirements of 40 CFR 51.164.
39

12. Provisions, pursuant to 40 CFR 51.165(a)(5)(ii), which require new source review for a 

source or modification which becomes major due to a relaxation in a federally-enforceable 

limit. Such sources and modifications are subject to new source review “as though 

construction had not yet commenced.”

Discussion: Subsection 12.3.7.4 (Relaxation in Enforceable Limitations), states that “At such time 

that a particular stationary source or modification becomes a major stationary source or major 

modification solely by virtue of a relaxation in any enforceable limitation which was established after 

August 7, 1980, on the capacity of the stationary source or modification otherwise to emit a pollutant, 

then the requirements of subsections 12.3.3 through 12.3.7 shall apply to the stationary source or 

modification as though construction had not yet commenced on the stationary source or 

modification.” This provision satisfies the regulatory requirement.

13. Provisions, pursuant to 40 CFR 51.307(b)(2), which identifies additional requirements for 

NSR for any new major source or major modification, proposing to locate in a 

nonattainment area, that may have an impact on visibility in any mandatory Class I Federal 

Area.

Discussion: Subsection12.3.10 requires consultation with the FLM “on a proposed major stationary 

source or major modification that may impact visibility in any Class I Area, in accordance with 40 CFR 

51.307.” This provision satisfies the regulatory requirement.

14. Provisions, pursuant to 40 CFR 51.165(a)(1)(iv)(C), which require that fugitive emissions 

be included in the major source applicability determination if the source belongs to one of 

the source categories listed in this section. Otherwise, fugitives may be excluded from the 

applicability determination.

Discussion: The definition of the term “major stationary source” in subsection 12.3.2(y), states that 

“[t]he fugitive emissions of a stationary source shall not be included in determining for any of the 

purposes of Section 12.3 whether it is a major stationary source, unless the source is a categorical 

stationary source or belongs to any other stationary source category which, as of August 7, 1980, 

was being regulated under Section 111 or 112 of the Act.” The definition of “categorical stationary 

source” in subsection 12.3.2(h) is consistent with the list of source categories identified in 40 CFR 

51.165(a)(1)(iv)(C). This is acceptable.

The definition of the term “major modification” in subsection 12.3.2(x) also requires exclusion of

fugitive emissions from the applicability determination unless the major stationary source is a 

categorical stationary source or belongs to any other stationary source category which, as of August 

7, 1980, was being regulated under Section 111 or 112 of the Act.” Although this language is 

consistent with the text of 40 CFR 51.165(a)(1)(v)(G) as of July 1, 2010, EPA has administratively 

stayed this paragraph indefinitely, effective March 30, 2011 (76 FR 17548) (final rule effectuating and 

extending stay of the final rule entitled "Prevention of Significant Deterioration (PSD) and 

Nonattainment New Source Review (NSR): Reconsideration of Inclusion of Fugitive Emissions" 

(“Fugitive Emissions Rule”) published December 19, 2008). The effect of this administrative stay was 

to revert the treatment of fugitive emissions in applicability determinations to the approach that 
40

applied prior to the Fugitive Emissions Rule, thus requiring that fugitive emissions be included in 

major modification applicability determinations for all source categories. 76 FR at 17550, 17551. The 

definition of “major modification” in subsection 12.3.2(x) is not consistent with this approach to the 

treatment of fugitive emissions in applicability determinations. We therefore propose to disapprove 

this definition. This disapproval, if finalized, would require Clark to revise Section 12.3 to require that 

fugitive emissions be included in major modification applicability determinations for all source 

categories.

15. Provisions, pursuant to section 173(a)(2), which require LAER, for a major source or 

major modification.

Discussion: The definition of “LAER” in Section 12.3, subsection 12.3.5, is consistent with the 

Federal definition in CAA section 171(3). Subsection 12.3.5.2 requires new major stationary sources 

to apply LAER for each regulated NSR pollutant that it would have the potential to emit in significant 

amounts. For major modifications, the regulation requires LAER for each regulated NSR pollutant for 

which there is a significant net emissions increase at the stationary source. This provision satisfies 

the regulatory requirement.

16. Additional Requirements Applicable to Ozone Non-attainment Areas

The general part D NSR permit requirements of title I apply within all nonattainment areas 

and are supplemented in ozone nonattainment areas by the specific requirements in subpart 

2 of part D. As discussed above, although Clark County was not initially classified under 

subpart 2 of part D, title I of the Act for the 1997 8-hour ozone NAAQS, EPA recently

classified the area as “marginal” nonattainment for the 1997 8-hour ozone standard 

effective June 13, 2012. 77 FR 28424 (May 14, 2012). Accordingly, the State is now 

obligated to submit NSR SIP revisions for Clark County meeting the applicable 

requirements of subpart 2 of part D, title I of the Act, including an offset ratio of 1.1 to 1 for 

NOx and VOC (see CAA 182(a)(4)) no later than June 13, 2013. We are not evaluating the 

submitted NSR rules for compliance with these subpart 2 requirements at this time but 

intend to do so following Clark’s submission of the required SIP revisions.

17. Additional Requirements Applicable to Particulate Matter (PM10) Non-attainment Areas

The general part D NSR permit requirements of title I apply within all nonattainment areas 

and are supplemented in PM10 nonattainment areas by the specific requirements in subpart 

4 of part D. PM10 NSR programs for nonattainment areas classified as “serious” must have 

the following provisions. A discussion of the corresponding Section 12 rule follows each 

provision.

1. Definition of the term “major stationary source” consistent with the section 189(b)(3) 

threshold of 70 tpy for PM10.
41

Discussion: The definition of “major stationary source” in Section 12.3, subsection 

12.3.2(y)(1)(A) satisfies this requirement.

2. Provisions under section 173(a)(1)(A) to ensure that new or modified major stationary 

sources obtain an offset ratio of at least 1 to 1.

Discussion: The offset ratio provisions in Section 12.3, subsection 12.3.6.5 and Table 12.3-1 

satisfy this requirement.

3. Under section 189(e), requirements applicable to major sources of PM10 are also 

applicable to major sources of PM10 precursors, except where the Administrator 

determines that such sources do not contribute significantly to PM10 levels which 

exceed the standards in the area.

Discussion: The offset ratio provisions in Section 12.3, subsection 12.3.6.5 and Table 12.3-1 

satisfy this requirement for major sources of PM10. With respect to PM10 precursors, EPA has 

previously determined that major stationary sources of PM10 precursors do not contribute 

significantly to PM10 levels in excess of the NAAQS in Clark County. See 68 FR 2954, 2958 

(January 22, 2003). Therefore, Clark is not obligated to require major sources of PM10

precursors to meet the same requirements as major sources of PM10.

4. Provisions to ensure that the significance threshold for a “major modification” is 15 tpy 

for PM10 and, presumptively, 15 tpy for each PM10 precursor.

Discussion: The definitions in Section 12.3 of “major modification” (subsection 12.3.2(x)) and 

“significant” (subsection 12.3.2(mm)) satisfy this requirement for PM10. As noted above in 

paragraph 3, Clark is not obligated to require the same for PM10 precursors.

Section 12.4 – Authority to Construct Application and Permit Requirements for Part 70 Sources

We reviewed this rule for compliance with EPA’s procedural requirements for permit issuance in 

40 CFR part 51, subpart I (sections 51.160 – 51.164), to the extent these procedures are not 

addressed by Section 12.1 for minor modifications at major sources, or by Section 12.2 or Section 

12.3 for new or modified major stationary sources. 

1. 40 CFR 51.160 – Legally enforceable procedures

(a) Each plan must set forth legally enforceable procedures that enable the State or local 

agency to determine whether the construction or modification of a facility, building, 

structure or installation or combination of these will result in (1) a violation of applicable 

portions of the control strategy; or (2) interference with attainment or maintenance of a 

national standard in the state in which the proposed source (or modification) is located or in 

a neighboring State.

Discussion: Section 12.4, subsection 12.4.1.1, prohibits the actual construction, modification or 
42

reconstruction of any “Part 70 source,” including any new or modified major source subject to PSD or 

NNSR requirements, without an ATC Permit issued by the Control Officer. Subsection 12.4.3.1 

specifies the required elements of an application for an ATC Permit under Section 12.4, including 

identification and descriptions of all emission points, process descriptions for all 

emissions-generating activities, the emission rates of all regulated air pollutants, and citations to and 

descriptions of all “applicable requirements” as defined in Section 0. See Section 12.4, subsection 

12.4.3.1(a). Permits for non-major Part 70 sources or minor modifications at major sources are 

governed by nearly identical requirements under subsection 12.4.3.2. For new or modified major 

sources subject to the PSD or NNSR requirements of Section 12.2 or Section 12.3, an application for 

an ATC Permit must also include all information necessary to process the application in accordance 

with those sections. See Section 12.4, subsection 12.4.3.1(b) and (c). These requirements for permit 

applications in Section 12.4 enable Clark to make the determinations specified in 40 CFR 51.160(a) 

for all Part 70 sources, including all new or modified major stationary sources.

(b) Such procedures must include means by which the State or local agency responsible for 

final decision-making on the application for approval to construct or modify will prevent 

such construction or modification if (1) it will result in a violation of applicable portions of 

the control strategy; or (2) it will interfere with the attainment or maintenance of a national 

standard.

Discussion: With respect to new or modified major stationary sources subject to PSD or NNSR, 

subsection 12.4.1.1(a) prohibits the actual construction of any new Part 70 source or modification or 

reconstruction of an existing Part 70 source without an ATC Permit from the Control Officer. See also 

Section 12.2, subsection 12.2.1.3 (prohibiting actual construction on any new major source or major 

modification subject to Section 12.2 without an ATC Permit issued in accordance with the 

requirements of Section 12.4) and Section 12.3, subsection 12.3.1.3 (corresponding prohibition for 

new and modified sources subject to Section 12.3). Subsection 12.4.3.1(e) requires that each ATC 

Permit issued for such a source contain, among other things, all “applicable requirements” (as 

defined in Section 0) and “[s]uch other conditions as necessary to demonstrate compliance with the 

requirements in Section 12.2 or Section 12.3 for construction, subject to those sections.” See 

subsection 12.4.3.1(e)(10). For any non-major Part 70 source or minor modification at a major 

source, paragraph 12.4.3.2(a)(1) requires that the applicant submit a demonstration that the new 

Part 70 source or modification would not cause an exceedance of the ambient air quality standards in 

Section 11 or an exceedance of ambient air increments specified in Section 12.2, subsection 12.2.3. 

Subsection 12.4.3.1(d) requires Clark to initiate public process under Section 12.2.16 on a permit 

application within one year after the application becomes “complete.” Under subsection 

12.2.16(b)(1), Clark may make preliminary determinations to approve, approve with conditions, or 

disapprove a permit application. Because Section 12.4 authorizes Clark to disapprove a permit 

application for failure to satisfy applicable requirements, these procedures authorize Clark to prevent 

construction or modification of a source where it would result in a violation of an applicable control 

strategy or interfere with the attainment or maintenance of a NAAQS. 

Section 12.4 does not contain a provision that explicitly authorizes Clark to prevent construction if the 

submitted documents do not adequately make the specified demonstrations. We recommend a 
43

clarification to Section 12.4 to specifically authorize Clark to prevent construction if the submitted 

application materials do not satisfy the applicable requirements. 

(c) The procedures must provide for the submission, by the owner of operator of the 

building, facility, structure, or installation to be constructed or modified, of such 

information on (1) the nature and amounts of emissions to be emitted by it or emitted by 

associated mobile sources; (2) the location, design, construction, and operation of such 

facility, building, structure, or installation as may be necessary to permit the State or local 

agency to make the determination referred to in paragraph (a) of this section.

Discussion: Section 12.4, subsection 12.4.3.1 (Application Submission, Processing and Issuance 

Requirements for Stationary Sources Subject to Sections 12.2 or 12.3) and subsection 12.4.3.2 

(Application Submission and Processing Requirements for Stationary Sources Not Subject to 

Section 12.2, Section 12.3, or subsection 12.4.3.3), specifies the required application submittal 

information. The information specified is sufficient for Clark to make the determinations referred to in 

40 CFR 51.160(a). This is acceptable.

(d) The procedures must provide that approval of any construction or modification must 

not affect the responsibility on the owner or operator to comply with applicable portions of 

the control strategy.

Discussion: Section 12.4 does not contain a provision to satisfy this requirement for purposes of 

regulating new and modified major stationary sources under Section 12.2 and Section 12.3. EPA is 

therefore proposing to disapprove Section 12.4 with respect to this requirement. This limited 

disapproval, if finalized, would require Clark to revise Section 12.4 (or Sections 12.2 and 12.3, as 

appropriate) to include a provision meeting the requirement in 40 CFR 51.160(d) and to submit the 

revised rule to EPA for approval into the Clark County portion of the Nevada SIP.

(e) The procedures must identify types and sizes of facilities, buildings, structures, or 

installations which will be subject to review under this section. The plan must discuss the 

basis for determining which facilities will be subject to review.

Discussion: Section 12.0 (Applicability, General Requirements and Transition Procedures) generally 

identifies the types and sizes of stationary sources that are subject to review under each of the 

Section 12 rules. See subsection 12.0.1 (Applicability). Additionally, Sections 12.1, 12.2, and 12.3

each contain more specific provisions that identify the types and sizes of stationary sources that are

subject to review under those respective rules. See, e.g., Section 12.1, subsection 12.1.0 

(Applicability); Section 12.2, subsection 12.2.1 (Applicability Procedures); and Section 12.3, 

subsection 12.3.1 (Applicability Procedures). Finally, Section 12.4 states that it applies to 

construction, modification, or reconstruction activities at “New Part 70 sources” and “Existing Part 70 

sources” as those terms are defined in subsection 12.4.2. See subsection 12.4.1.1. Clark’s Minor 

NSR TSD (at 3-3 through 3-27) discusses Clark’s basis for determining which facilities will be subject 

to review under Section 12.1. These provisions are acceptable.

(f) The procedures must discuss the air quality data and the dispersion or other air quality 
44

modeling used to meet the requirements of this subpart. (1) All applications of air quality 

modeling involved in this subpart shall be based on the applicable models, data bases, and 

other requirements specified in appendix W of this part (Guidelines on Air Quality 

Models). (2) Where an air quality model specified in appendix W of this part (Guideline on 

Air Quality Models) is inappropriate, the model may be modified or another model 

substituted. Such a modification or substitution of a model may be made on a case-by-case 

basis or, where appropriate, on a generic basis for a specific State program. Written 

approval of the EPA must be obtained for any modification or substitution. In addition, use 

of a modified or substituted model must be subject to notice and opportunity for public 

comment under procedures set forth in 40 CFR 51.102.

Discussion: These requirements are adequately addressed by subsection 12.2.11 in Section 12.2 

(Permit Requirements For Major Sources in Attainment Areas). See discussion of Section 12.2 

above.

2. 40 CFR 51.161 – Public availability of information

(a) The legally enforceable procedures in 40 CFR 51.160 must also require the State or 

local agency to provide opportunity for public comment on information submitted by 

owners and operators. The public information must include the agency’s analysis of the 

effect of construction or modification on ambient air quality, including the agency’s 

proposed approval or disapproval.

Discussion: Section 12.4, subsection 12.4.3.1(d) states that, for any source subject to the 

requirements of Section 12.2 (PSD) or Section 12.3 (NSR), within one year after the date that an 

ATC permit application is determined to be complete, the Control Officer must initiate the public 

participation procedures in subsection 12.2.16. See also Section 12.3, subsection 12.3.8 (Public 

Participation). These provisions satisfy the public process requirements of 40 CFR 51.161 for new or 

modified major stationary sources. Subsection 12.4.3.2(a) states that, for any permit revision not

subject to Section 12.2, Section 12.3, or Section 12.4.3.3, the public participation procedures in 

Section 12.1, subsection 12.1.5.3 shall apply. See subsection 12.4.3.2(a)(3). These provisions 

satisfy the public process requirements of 40 CFR 51.161 for minor modifications at existing major 

stationary sources.

(b) For the purposes of paragraph (a) of this section, opportunity for public comment shall 

include, as a minimum, (1) Availability for public inspection in at least one location in the 

area affected of the information submitted by the owner or operator and of the State or local 

agency’s analysis of the effect on air quality; (2) A 30-day period for submittal of public 

comment; and (3) A notice by prominent advertisement in the area affected of the location 

of the source information and analysis specified in paragraph (b)(1) of this section. 

Discussion: For both PSD and Nonattainment NSR purposes, the public process requirements of 40 

CFR 51.161 are satisfied by Section 12.2, subsection 12.2.16 (Public Participation), and Section 

12.3, subsection 12.3.8 (Public Participation). These provisions satisfy the regulatory requirement for 
45

new or modified major stationary sources.

(c) Where the 30-day comment period required in paragraph (b) of this section would 

conflict with existing requirements for acting on requests for permission to construct or 

modify, the State may submit for approval a comment period which is consistent with such 

existing requirements.

Discussion: This is a discretionary component of a PSD or Nonattainment NSR program that Clark’s 

submitted regulations do not contain. This is acceptable.

(d) A copy of the notice required by paragraph (b) of this section must also be sent to the 

EPA through the appropriate Regional Office, and to all other State and local air pollution 

control agencies having jurisdiction in the region in which such new or modified 

installation will be located. The notice also must be sent to any other agency in the region 

having responsibility for implementing the procedures required under this subpart. For 

lead, a copy of the notice is required for all point sources. The definition of point source for 

lead is given in 40 CFR 51.100(k)(2).

Discussion: For both PSD and Nonattainment NSR purposes, the public process requirements of 40 

CFR 51.161 are satisfied by Section 12.2, subsection 12.2.16 (Public Participation), and Section 

12.3, subsection 12.3.8 (Public Participation). These provisions satisfy the regulatory requirement for 

new or modified major stationary sources.

3. 40 CFR 51.162 – Identification of responsible agency

Each plan must identify the State or local agency which will be responsible for meeting the 

requirements of this subpart in each area of the State. Where such responsibility rests with 

an agency other than an air pollution control agency, such agency will consult with the 

appropriate State or local air pollution control agency in carrying out the provisions of this 

subpart.

Discussion: Nevada law identifies the State Department of Conservation and Natural Resources 

(DCNR) as the State agency responsible for issuing permits to new or modified sources in all areas 

of the State of Nevada, except within counties whose populations exceed 100,000. In such counties, 

Nevada law provides that the applicable permitting agency is the district board of health, county 

board of health or board of county commissioners. See NRS 445B.300 and NRS 445B.500, both of 

which were approved on August 31, 2006 (71 FR 51766). Clark County is one of only two counties in 

Nevada whose populations exceed 100,000; and the County has its own air pollution control agency.

Section 12.0 identifies Clark as the agency that will be implementing stationary source permitting 

requirements in Clark County, including Section 12.1.

The only exception to this basic regulatory structure for permitting of sources in Nevada relates to 

certain power plants that are subject to State, not county, jurisdiction notwithstanding their location 

within Clark County. See NRS 445B.500(5), approved into the SIP as noted above; see also Section 

12.0, subsection 12.0.1. Thus, the Nevada SIP identifies the State or local agency which is 
46

responsible for meeting the requirements of 40 CFR part 51, subpart I, in Clark county.

4. 40 CFR 51.163 – Administrative procedures

The plan must include the administrative procedures, which will be followed in making the 

determination specified in paragraph (a) of 40 CFR 51.160.

Discussion: Section 12.4 provides adequate administrative procedures to be followed by Clark in 

making the determinations specified in 40 CFR 51.160(a), including application requirements, 

requirements for environmental evaluations, completeness determinations, preliminary findings, 

public participation, and considerations in the final decision to issue or deny a permit. See, e.g.,

subsections 12.4.1.1(a), 12.4.3.1, and 12.4.3.2.

5. 40 CFR 51.164 – Stack height procedures

Such procedures must provide that the degree of emission limitation required of any source 

for control of any air pollutant must not be affected by so much of any source’s stack height 

that exceeds good engineering practice or by any other dispersion technique, except as 

provided in 40 CFR 51.118(b). Such procedures must provide that before a State issues a 

permit to a source based on a good engineering practice stack height that exceeds the height 

allowed by 40 CFR 51.100(ii)(1) or (2), the State must notify the public of the availability 

of the demonstration study and must provide opportunity for public hearing on it. This 

section does not require such procedures to restrict in any manner the actual stack height of 

any source.

Discussion: Clark’s PSD program in Section 12.2 contains a provision satisfying this requirement (in 

subsection 12.2.7.3), but neither Section 12.3 nor Section 12.4 contains a corresponding 

requirement for the Nonattainment NSR program. We propose to disapprove Clark County’s 

Nonattainment NSR program with respect to this requirement. This limited disapproval, if finalized, 

would require Clark to add a provision to Section 12.3 or Section 12.4 that satisfies the requirements 

of 40 CFR 51.164.

Section 110(l) of the Act

Section 110(l) states: “Each revision to an implementation plan submitted by a State under this 

chapter shall be adopted by such State after reasonable notice and public hearing. The 

Administrator shall not approve a revision of a plan if the revision would interfere with any 

applicable requirement concerning attainment and reasonable further progress (as defined in 

section 7501 of this title), or any other applicable requirement of this chapter.”

With respect to the procedural requirements of CAA section 110(l), based on our review of the 

public process documentation included in the February 11, 2010, September 1, 2010, and May 22, 

2012 submittals, we find that DAQ has provided sufficient evidence of public notice and 
47

opportunity for comment and public hearings prior to adoption and submittal of these rules to 

EPA. With respect to the substantive requirements of section 110(l), as discussed further below, 

our approval of the Clark County NSR SIP submittal (and replacement or supersession of the 

existing SIP NSR rules) would strengthen the applicable SIP in some specific respects and would 

relax the SIP in other specific respects. Taken in its entirety, we find that the SIP revision 

represents a strengthening of Clark County’s minor NSR, PSD, and Nonattainment NSR programs 

compared to the existing SIP programs that we approved in 1982 and 2004, and that our approval 

of the NSR SIP submittal would not interfere with any applicable requirement concerning 

attainment and reasonable further progress (RFP) or any other applicable requirement of the Act.

The most significant deficiencies that we have identified in the submitted NSR rules, as discussed 

in detail earlier in this TSD, are generally as follows: (1) the absence of minor NSR provisions that 

ensure protection of the 2006 PM2.5 NAAQS and 2008 Lead (Pb) NAAQS; (2) minor NSR 

applicability provisions that do not cover stationary sources of PM2.5; (3) deficiencies in the 

definitions of certain terms used in PSD and Nonattainment NSR (NNSR) applicability 

determinations; (4) definition of “regulated NSR pollutant” that does not adequately address PSD 

and NNSR requirements for regulation of condensable particulate matter; (5) deficiencies in the 

criteria for assessing the quality (or “integrity”) of emission reduction credits used to satisfy 

NNSR offset requirements; and (6) the absence of minor NSR or NNSR provisions to ensure that 

the air quality impacts of stationary sources are not underestimated due to stack heights that exceed 

good engineering practice or unacceptable air dispersion modeling techniques. We identify these 

as the “most significant” deficiencies because these are the most likely to affect pollutant 

emissions within Clark County, compared to other deficiencies that we do not expect would 

significantly affect emissions levels (e.g., administrative requirements for permit issuance).

Many of these deficiencies are related to requirements that came into effect after we last approved 

Clark County’s NSR programs in 1982 and 2004. For example, minor NSR SIP revisions to 

implement the 2006 PM2.5 NAAQS and 2008 Lead (Pb) NAAQS were due in 2009 and 2011, 

respectively. See CAA 110(a). Similarly, SIP revisions to implement EPA’s PSD and NNSR 

requirements for condensable particular matter were due in 2011. See 73 FR 28321 (May 16, 

2008). With respect to all of these post-2005 requirements, which the existing SIP NSR program 

does not address, we believe it is reasonable to conclude that our approval of the NSR SIP 

submittal as a revision to the Nevada SIP would not interfere with any applicable requirement 

concerning attainment and RFP or any other applicable requirement of the Act, because there is 

no applicable requirement in the existing SIP program that would be affected by the deficiencies 

in the submitted NSR rules. 

As to the remaining deficiencies, we have evaluated these together with the most significant 

differences between the two NSR programs (SIP-approved versus the NSR SIP submittal) to 

evaluate the overall effect that our approval of the NSR SIP submittal might have on the stringency 

of DAQ’s permit programs and the potential air quality impacts of these program revisions. First, 

certain PSD and NNSR definitions governing applicability determinations in Section 12.2 and 

Section 12.3 are not as stringent as the corresponding Federal definitions in 40 CFR 51.166 and 

51.165, respectively. Second, the offset ratio in Section 12.3 is 1:1, compared to a more stringent 
48

ratio of 2:1 in the existing SIP NSR program, and the criteria in Section 12.3 for evaluating the 

integrity of emissions reduction credits used to satisfy NNSR offset requirements are not adequate 

to assure actual emission reductions. Third, the minor NSR program and NNSR program 

(Sections 12.1, 12.3, and 12.4 to some extent) both lack provisions to ensure that the air quality 

impacts of stationary sources are not underestimated due to stack heights that exceed good 

engineering practice or unacceptable air dispersion modeling techniques. Fourth, DAQ has 

established public notice thresholds for minor NSR (Section 12.1) that exclude from public review 

the following types of less-environmentally significant minor sources: (1) new minor sources with 

potential emissions of NAAQS pollutants below 50 tons per year (tpy) for CO; 40 tpy for VOCs, 

SO2, or NOx; 15 tpy for PM10; and 0.6 tpy for Lead (Pb) (see subsection 12.1.5.3), and (2) 

modifications at existing minor sources that result in PTE increases less than 40 tpy for SO2; 35 tpy 

for CO; 20 tpy for VOC or NOx; and 7.5 tpy for PM10 (see subsection 12.1.6(a)(7)). Compare 

with SIP Section 12, subsection 12.1.1.1 (requiring preconstruction review for “any new stationary 

source” or “modification” without emissions-based applicability thresholds). Finally, the control 

standard for minor sources has been changed from “Best Available Control Technology” under the 

SIP minor NSR program to “Reasonably Available Control Technology” under submitted Section 

12.1 (see subsection 12.1.3.6(b), (c)).

With respect to the scope of the NSR program, the deficiencies in the applicability-related 

definitions in Sections 12.2 and 12.3 and the new de minimis thresholds established in Section 12.1 

could potentially reduce the number of new or modified stationary sources that are subject to 

preconstruction review under these programs and thereby relax the NSR program for new and 

modified sources compared to the SIP-approved program. As to the minor NSR control standard, 

the NNSR offset requirements, and the absence of provisions related to stack heights, the 

submitted NSR rules may result in application of less-stringent control technologies on minor 

sources (from BACT to RACT), potential under estimations of the air quality impacts of stationary 

source operations and, with respect to ozone precursor and PM10 emissions, offset transactions that 

may not achieve adequate emission reductions. 

Several significant improvements in the submitted NSR rules should be considered in assessing 

the overall impact of these potential program relaxations. First, the potential for reduced numbers 

of regulated sources is offset to at least some extent by new provisions in Section 12.1 that 

establish a five-year permit term, thereby mandating a regular review of all minor source permit 

conditions and source operations, and provisions providing that DAQ may re-open a minor NSR 

permit at any time for cause. See Minor NSR SIP Submittal, Appendix B: “Technical 

Requirements.” Second, Section 12.1 requires that each minor NSR permit contain a number of 

important types of permit terms and conditions which are more specific than required under the 

SIP NSR program and that strengthen the enforceability of the program – for example, physical 

descriptions of each emission unit, emission limitations that ensure protection of ambient air 

quality standards, and more clearly defined monitoring, recordkeeping, and reporting 

requirements modeled on the CAA’s title V operating permit program. Compare Section 12.1, 

subsection 12.1.4.1 (Term and Conditions) with SIP Section 12, subsection 12.8.1.1 (conditions of 

ATC). Third, Section 12.1 contains important new conditions for issuance of minor NSR 

permits, such as the requirement to assure compliance with all applicable SIP requirements. See 
49

Section 12.1, subsection 12.1.5.1 (Action on Application) compared to SIP Section 12 (as adopted 

October 7, 2003), subsection 12.8.2 (ATC issuance requirements). Fourth, both the minor source 

program in Section 12.1 and the major source programs in Sections 12.2 and 12.3 rely on several 

new or revised definitions of key terms that are more consistent with Federal definitions (in CAA 

302 and 40 CFR part 51, subpart I) than corresponding definitions in the SIP NSR program. See, 

e.g., definition of “potential to emit” in Section 011 compared to definition of “total potential to 

emit” in SIP Section 12 (as adopted October 7, 2003), subsection 12.1.6.1; new definition of 

“emission limit” or “emission limitation” in Section 0. Finally, with respect to the difference 

between BACT and LAER for minor stationary sources in Clark County, supporting information 

submitted by DAQ indicates that the shift away from the existing BACT standard in the SIP is not 

likely to affect emissions to any significant degree given the ambiguities in the SIP rule which 

undermined the practical enforceability of this standard, and that the RACT standard in submitted 

Section 12.1 is expected to be equally effective in controlling emissions at minor sources, if not 

more so given the enhanced compliance provisions. See Minor NSR TSD at 3-20 to 3-28 and 

Minor NSR SIP Submittal, Appendix B: “Technical Requirements.” 

With respect to offset requirements, we note that the SIP NSR program did not require offsets for 

VOC or NOx because Clark County was not designated nonattainment for any ozone NAAQS at 

the time when we approved the SIP program in 2004. See Section 59 (Emission Offsets), as 

adopted October 7, 2003 at Table 59.1.2. The NSR control (LAER) and offset requirements in 

submitted Section 12.3 therefore ensure greater reductions of ozone precursor emissions compared 

to the SIP program, which required neither LAER nor offsets for NOx or VOC. For PM10 purposes, 

the SIP NSR program required that major stationary sources (i.e., sources with PTE of 70 tpy or 

more) obtain PM10 offsets at a ratio of 2:1, whereas the submitted Section 12.3 requires those same 

sources to obtain PM10 offsets at a ratio of 1:1. See Section 59 (Emission Offsets) (as adopted 

October 7, 2003) at Table 59.1.2 and Section 12.3 (Permit Requirements for Major Sources in 

Nonattainment Areas) (as adopted May 18, 2010) at Table 12.3-1. This relaxation in the offset 

ratio for PM10 sources applies only to stationary sources locating within the boundaries of the PM10

nonattainment area in the Las Vegas planning area (hydrographic area #212), and appears to be 

offset by the overall strengthening in the NSR program, as discussed above with respect to both 

major and minor sources throughout Clark County. Significantly, the submitted Section 12.2 

includes new PSD provisions to regulate new or modified major stationary sources of greenhouse 

gases (GHGs) and PM2.5, both of which are entirely unregulated under the existing SIP PSD 

program. In addition, both Section 12.2 and Section 12.3 satisfy the requirements of EPA’s 2002 

NSR Reform rules, with limited exceptions.

In sum, the new and revised provisions in the submitted NSR rules enable DAQ to review source 

operations on a more regular basis; require DAQ to make specific determinations related to air 

 11 Section 12.1 establishes emission-based applicability thresholds based on a definition of “potential to emit” in 

submitted Section 0 that is generally equivalent to EPA’s definition of this term in 40 CFR 51.165 and 51.166. The SIP 

NSR program in Section 12 (as adopted October 7, 2003), contains applicability provisions based on a definition of 

“total potential to emit” that is generally more expansive but allows, on the other hand, for certain engines categorized 

as “special mobile equipment” to be inappropriately exempt from the calculation of PTE (see SIP Section 12, 

subsection 12.1.6.1).
50

quality impacts and applicable SIP requirements as part of permit issuance; improve the 

enforceability of the NSR program through the establishment of more detailed compliance 

requirements and improved definitions of important terms; establish NNSR requirements for 

ozone precursor emissions that were not required under the existing SIP program; and establish 

new PSD provisions for the regulation of GHG and PM2.5 emission sources. We find that, on 

balance, these NSR program improvements outweigh the potential relaxations discussed above 

compared to the existing SIP program. In addition, we are unaware of any reliance by DAQ on 

the continuation of any aspect of the permit-related rules in the Clark County portion of the 

Nevada SIP for the purpose of continued attainment or maintenance of the NAAQS. Given all 

these considerations, we propose to conclude that our approval of these updated NSR regulations 

into the Nevada SIP would not interfere with any applicable requirement concerning attainment 

and RFP or any other applicable requirement of the Act.12

Conclusion. For the reasons set forth above, we can approve the submitted NSR program under 

section 110(l) of the Act.

Section 193 of the Act

Section 193 of the Act, which was added by the Clean Air Act Amendments of 1990, 

includes a savings clause which provides, in pertinent part: “No control requirement in effect, or 

required to be adopted by an order, settlement agreement, or plan in effect before November 15, 

1990, in any area which is a nonattainment area for any air pollutant may be modified after 

November 15, 1990, in any manner unless the modification insures equivalent or greater emission 

reductions of such air pollutant.” 

EPA does not believe that NSR programs are control requirements for the purposes of 

section 193. See 70 FR 39413, at 39417 (July 8, 2005). However, we recognize that, on December 

22, 2006, the D.C. Circuit issued a decision on South Coast Air Quality Management District v. 

EPA, No. 14-1200, that may lead EPA to modify its interpretation of “control requirement” for the 

purposes of CAA section 193. Nonetheless, even if NSR were considered a “control requirement,” 

we find that the submitted NSR rules would insure equivalent or greater emission reductions 

compared to the SIP-approved NSR programs in the two nonattainment areas in Clark County (for 

the 1997 8-hour ozone NAAQS and the PM10 NAAQS) for the following reasons. For ozone 

purposes, the pre-1990 SIP NSR program contained no offset requirement because Clark County 

was not designated nonattainment for any ozone NAAQS at that time. See Section 15.14.4.3 (as 

adopted 1981). The NSR control (LAER) and offset requirements in submitted Section 12.3 

therefore ensure greater reductions of ozone precursor emissions compared to the pre-1990 

 12 With respect to the two NAAQS for which portions of Clark County remain designated nonattainment (PM10 and 

1997 8-hour ozone), EPA has recently determined based on ambient air monitoring data that Clark County is attaining 

both of these standards. See 75 FR 45485 (August 3, 2010) (Determination of Attainment for PM10 for the Las Vegas 

Valley Nonattainment Area) and 76 FR 17343 (March 29, 2011) (Determination of Attainment for the Clark County 

1997 8-Hour Ozone Nonattainment Area).
51

program, which required neither LAER nor offsets for NOx or VOC. For PM10 purposes, the 

pre-1990 NSR program required that PM10 sources with PTE of 25 tpy or more obtain PM10 offsets 

at a ratio of 1:1, whereas the submitted Section 12.3 requires sources with PTE of 70 tpy or more to 

obtain PM10 offsets at that same ratio. Compare Section 15.14.4.3 (as adopted 1981) with Section 

12.3 (Permit Requirements for Major Sources in Nonattainment Areas) (as adopted May 18, 2010) 

at Table 12.3-1. We believe, however, that this relaxation in the applicability threshold for PM10

offsets is outweighed by the improvements in the applicability provisions and compliance 

requirements of both the minor NSR program (Section 12.1), which applies throughout Clark 

County including the Las Vegas Valley, and the Nonattainment NSR program (Section 12.3), as 

discussed above. We therefore conclude that the submitted NSR program will provide for 

equivalent or greater emissions reductions as the existing SIP NSR program for the two applicable 

nonattainment pollutants, ozone and PM10.

Conclusion. For the reasons set forth above, we can approve the submitted NSR program under 

section 193 of the Act.

Recommendations for Rule Revisions

We discuss below rule revisions or clarifications that are not currently bases for disapproval but 

that we recommend DAQ adopt at its earliest opportunity.

(1) Section 0 (Definitions): The definition of “potential to emit” generally tracks EPA’s definition 

of this term in 40 CFR 51.165(a)(1)(iii) and 40 CFR 51.166(b)(4) but uses the phrase 

“enforceable as a practical matter” in lieu of “federally enforceable.” EPA generally allows for 

recognition of limits that are “enforceable as a practical matter” provided the relevant rule 

provides criteria by which a limit will be judged to be “practically enforceable” or 

“enforceable as a practical matter.” Consistent with these principles, we recommend that DAQ 

revise the definition of “potential to emit” in Section 0 to include such criteria or add a new 

definition for the term “enforceable as a practical matter” in Section 0. We note that the criteria 

provided in Section 12.1, subsection 12.1.7, for establishing voluntarily accepted emission 

limitations and standards that are “enforceable as a practical matter” are acceptable and may be 

used in the Section 0 definition of “potential to emit” as well.

(2) Section 12.1 (Minor NSR): EPA revised the NAAQS for NO2 and SO2 in 2010, and minor 

NSR SIP revisions to implement these standards are due January 22, 2013 and June 2, 2013, 

respectively. See 75 FR 6474 (February 9, 2010) (final rule establishing new 1-hour 

standard for NO2) and 75 FR 35520 (June 22, 2010) (final rule establishing new 1-hour 

standard for SO2). We recommend that DAQ revise its definition of “ambient air quality 

standards” in Section 11 to include these additional NAAQS and to submit the revised rule as a 

SIP revision prior to these upcoming deadlines. Alternatively, we recommend that DAQ revise 

Section 12.1, subsection 12.1.4.1(c), to reference the “National Ambient Air Quality 

Standards” instead of “ambient air quality standards” to ensure protection of all of the NAAQS 
52

in the issuance of permits for new or modified minor sources, consistent with the requirements 

of 40 CFR 160(a).

(3) Section 12.1 (Minor NSR): Under subsection 12.1.6(d) (“Changes that can be made with prior 

notice”), we recommend that Clark revise subparagraph (d)(5) to clarify that this provision 

does not cover any change that may increase the source’s PTE by “significant” amounts. 

Although the rule currently provides that any change that triggers a new applicable 

requirement does not qualify for this procedure, it should be clear in the rule that where a 

change may potentially increase the source’s PTE by significant amounts, the source should 

submit an application for a significant permit revision. This would ensure that DAQ can 

evaluate the potential emissions impacts of the change before the source proceeds with 

construction. Additionally, we note that the reference to paragraph (2)(E) in subsection 

12.1.6(b) appears to be a typographical error and should be corrected by replacing (E) with 

(D).

(4) Section 12.2 (PSD): In DAQ’s definition of “baseline actual emissions” in subsection 

12.2.2(c), we recommend that subparagraph (1)(B)(i) be relabeled as a separate paragraph 

((1)(C) or(1)( E)), as it is not appropriate to characterize this provision as a subset of paragraph 

(1)(B). See 40 CFR 51.166(47)(ii). Other provisions that cross-reference subparagraph 

(1)(B)(i) will then need to be revised accordingly. For example, paragraph (1)(D) will need to 

be revised to include a reference to the new paragraph (current subparagraph (1)(B)(i), 

relabeled as appropriate). See 40 CFR 51.166(47)(ii)(e).

(5) Section 12.2 (PSD): Because NDEP shares PSD increment-tracking responsibility with Clark 

for baseline areas inside Clark County, we recommend that Clark revise subsection 12.2.15.1 

to provide for copies of permit applications to also be sent to NDEP. NDEP coordination 

should also occur prior to public review to ensure proper analysis of increment consumption.

(6) Section 12.2 (PSD): Subsection 12.2.19.2(a) currently states that the listed definitions apply 

and that “[w]hen a term is not defined in these paragraphs, it shall have the meaning given in 

Section 0, Section 12.4 or the Act.” We recommend that Clark revise subsection 12.2.19.2(a) 

to clarify the applicable definitions. To the extent that Clark intended for the definitions 

provided in Section 12.2 (subsection 12.2.2) to apply before any of the other cited provisions, 

we recommend clarifying the provision accordingly.

(7) Section 12.3 (Nonattainment NSR): In Table 12.3-1 of Section 12.3, which provides the offset 

ratios applicable in the nonattainment portions of Clark County, the phrase “nonattainment 

without designation” is confusing as any nonattainment area is, by definition, designated. As 

part of its rulemaking to incorporate the 1.1 to 1 offset ratio required pursuant to EPA’s subpart 

2 classification of the Las Vegas Valley area for the 1997 8-hour ozone NAAQS, we 

recommend that DAQ also revise Table 12.3-1 to clarify that the revised offset ratio for NOx

and VOC applies throughout the “marginal” ozone nonattainment area in Clark County. – for 

example, by replacing "Nonattainment without Designation" with "Marginal Nonattainment 

Area" and providing the required subpart 2 offset ratio of 1.1 to 1.
53

EPA’s Proposed Action

Pursuant to section 110(k)(3) of the Act, we are proposing a limited approval and limited 

disapproval of the submitted NSR rules. We are proposing to approve the submitted NSR rules 

based on our determination that, for the most part, the rules satisfy the applicable statutory and 

regulatory provisions governing regulation of stationary sources under CAA section 110(a)(2)(C), 

including the permitting requirements for major stationary sources in parts C and D of title I of the 

Act. In support of this proposed action, we have concluded that our approval of the submitted NSR 

rules (and replacement or supersession of the existing SIP NSR rules) would comply with section 

110(l) of the Act because the revised program as a whole would not interfere with continued 

attainment of the NAAQS in Clark County. Simultaneously, we are proposing a limited 

disapproval of specified provisions in the submitted NSR rules because they do not fully satisfy the 

applicable CAA and regulatory requirements, as summarized below.

With respect to the Minor NSR program, Section 12.1 does not provide a means for determining 

whether the construction or modification of a stationary source will result in a violation of 

applicable portions of the control strategy or interference with attainment or maintenance of the 

2006 24-hour PM2.5 NAAQS and the 2008 Lead NAAQS, because the rule references an outdated 

definition of “ambient air quality standards”; contains inappropriate language regarding federal 

enforceability of permits issued under Section 12.1; does not contain provisions to ensure that 

approval of any construction or modification must not affect the responsibility on the owner or 

operator to comply with applicable portions of the control strategy; provides inappropriate 

exemptions for sources identified in a separate rule that is not SIP-approved (Section 12.5); does 

not contain applicability provisions that cover sources of PM2.5 or PM2.5 precursor emissions; and 

does not contain provisions designed to ensure that the air quality impacts of stationary sources are 

not underestimated due to stack heights that exceed good engineering practice or unacceptable air 

dispersion modeling techniques.

With respect to the PSD permit program, Section 12.2 contains definitions for the terms 

“allowable emissions,” “baseline actual emissions,” “net emissions increase,” “major 

modification,” and “regulated NSR pollutant” that are not entirely consistent with EPA’s 

definitions in 40 CFR 51.166; contain a provision governing adjustment of PALs to incorporate

requirements that become effective during the term of a PAL that is not entirely consistent with 

EPA’s requirements; and does not contain, either in Section 12.2 or in Section 12.4, a provision 

addressing the requirement in 40 CFR 51.160(d) to provide that approval of any construction or 

modification must not affect the responsibility on the owner or operator to comply with applicable 

portions of the control strategy.

Finally, with respect to the Nonattainment NSR program, Section 12.3 contains provisions 

governing offsets and calculation of emission reduction credits that do not ensure the integrity of 

offset calculations and that reference a separate rule that is not SIP-approved (Section 12.7) for 

important criteria governing these calculations; contains definitions for the terms “baseline actual 
54

emissions,” “major modification,” and “regulated NSR pollutant” that are not entirely consistent 

with EPA’s definitions in 40 CFR 51.165; allows for interpollutant trades between certain 

pollutants without satisfying EPA’s criteria for approval of such trades; does not contain 

provisions designed to ensure that the air quality impacts of stationary sources are not 

underestimated due to stack heights that exceed good engineering practice or unacceptable air 

dispersion modeling techniques; and does not contain, either in Section 12.3 or in Section 12.4, a 

provision addressing the requirement in 40 CFR 51.160(d) to provide that approval of any 

construction or modification must not affect the responsibility on the owner or operator to comply 

with applicable portions of the control strategy.