The EPA Regional Administrator, Jared Blumenfeld signed the following rule on September 30, 2015 and 

EPA is submitting it for publication in the Federal Register (FR). While we have taken steps to ensure the 

accuracy of this version of this rule, it is not the official version. Please refer to the official version in a 

forthcoming FR publication appearing on the Government Printing Office website, 

http://fdsys.gpo.gov/fdsys/search/home.action, and on www.regulations.gov in Docket Number EPA-R09-

OAR-2015-0645.

6560-50-P

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2015-0645; FRL-]

Air Plan Approval; Phoenix, Arizona; Second 10-Year Carbon Monoxide Maintenance 

Plan.

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

SUMMARY: The Environmental Protection Agency (EPA) is proposing approval of a State 

Implementation Plan (SIP) revision submitted by the State of Arizona. On March 9, 2005, the 

EPA redesignated Phoenix, Arizona from nonattainment to attainment for the carbon monoxide 

(CO) National Ambient Air Quality Standards (NAAQS) and approved the State’s plan 

addressing the area’s maintenance of the NAAQS for ten years. On April 2, 2013, the State of 

Arizona submitted to the EPA a second maintenance plan for the Phoenix area that addressed 

maintenance of the NAAQS for an additional ten years. The EPA is also proposing to find 

adequate and approve a transportation conformity motor vehicle emissions budgets (MVEB) for 

the year 2025 and beyond.

DATES: Comments must be received on or before [INSERT DATE 30 DAYS AFTER DATE 

OF PUBLICATION IN THE FEDERAL REGISTER].

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-OAR-2015-
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30, 2015. We have taken steps to ensure the accuracy of this version, but it is not the official version.

2

0645, to the Federal eRulemaking Portal: http://www.regulations.gov. Follow the online 

instructions for submitting comments. Once submitted, comments cannot be edited or 

withdrawn. The EPA may publish any comment received to its public docket. Do not submit 

electronically any information you consider to be Confidential Business Information (CBI) or 

other information whose disclosure is restricted by statute. If you need to include CBI as part of 

your comment, please visit http://www2.epa.gov/dockets/commenting-epa-dockets for 

instructions. Multimedia submissions (audio, video, etc.) must be accompanied by a written 

comment. The written comment is considered the official comment and should include 

discussion of all points you wish to make.

For additional submission methods, the full EPA public comment policy, and general 

guidance on making effective comments, please visit http://www2.epa.gov/dockets/commentingepa-dockets.

FOR FURTHER INFORMATION CONTACT: John Kelly, Planning Office (Air-2), Air 

Division, Region 9, Environmental Protection Agency, 75 Hawthorne Street, San Francisco, 

California 94105, (415) 947-4151, kelly.johnj@epa.gov.

SUPPLEMENTARY INFORMATION:

Definitions

For the purpose of this document, we are giving meaning to certain words or initials as follows:

(i) The words or initials Act or CAA mean or refer to the Clean Air Act, unless the 

context indicates otherwise.

(ii) The initials AADT mean or refer to Annual Average Daily Traffic.

(iii) The initials ADEQ mean or refer to Arizona Department of Environmental Quality.
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(iv) The initials ANP mean or refer to Annual Monitoring Network Plans, commonly 

known as Annual Network Plans or ANP

(v) The initials CO mean or refer to carbon monoxide.

(vi) The words EPA, we, us or our mean or refer to the United States Environmental 

Protection Agency.

(vii) The initials MAG mean or refer to the Maricopa Association of Governments.

(viii) The initials MCAQD mean or refer to the Maricopa County Air Quality Department.

(ix) The initials MVEB mean or refer to Motor Vehicle Emissions Budget.

(x) The initials mtpd mean or refer to metric tons per day.

(xi) The initials NAAQS mean or refer to the National Ambient Air Quality Standards.

(xii) The initials ppm mean or refer to parts per million. 

(xiii) The initials RTP mean or refer to Regional Transportation Plan.

(xiv) The initials SIP mean or refer to State Implementation Plan.

(xv) The initials TIP mean or refer to Transportation Improvement Plan.

(xvi) The initials TSA mean or refer to an air monitoring program Technical Systems 

Audit.

(xvii) The words Arizona and State mean or refer to the State of Arizona.

I. Background

A. Phoenix (Maricopa County), Arizona Attainment Status

Under the Clean Air Act (CAA) Amendments of 1990, the Phoenix metropolitan area in 

Maricopa County, Arizona (hereinafter referred to as Phoenix, the Phoenix area or the area) was 

designated and classified as a moderate CO nonattainment area. On July 29, 1996, the EPA 
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found that the area had not attained the CO NAAQS by the moderate attainment date and the 

area was reclassified to serious nonattainment by operation of law, effective August 28, 1996. 61 

FR 39343.

The primary CO NAAQS are attained when ambient concentration design values do not 

exceed either the 1-hour 35 parts per million (ppm) standard or the 8-hour 9 ppm standard more 

than once per year. 40 CFR 50.8(a). There have been no violations in Phoenix of the 1-hour CO

standard since 1984 and no violations of the 8-hour standard since 1996. 2013 Maintenance Plan, 

page 1-1. The EPA determined in 2003 that the area had attained the CO NAAQS by the area’s 

December 31, 2000 attainment deadline. 68 FR 55008, September 22, 2003. This determination 

did not affect the designation of the area as nonattainment or its classification as a serious area.

On May 30, 2003, the State of Arizona submitted a request to the EPA to redesignate 

Phoenix from nonattainment to attainment for the CO NAAQS. Along with this request, the State

submitted a CAA section 175A(a) maintenance plan which demonstrated that the area would 

maintain the CO NAAQS for the first 10 years following our approval of the redesignation 

request (“2003 CO Maintenance Plan”). We approved the State’s redesignation request and 10-

year maintenance plan on March 9, 2005, effective April 8, 2005. 70 FR 11553. For a detailed 

history of the CO planning efforts in the area up to 2004, please see the Technical Support 

Document that accompanied the EPA’s proposal to approve the first 10-year maintenance plan 

for the area. 69 FR 60328, October 8, 2004.

B. 2013 CO Maintenance Plan

Eight years after an area is redesignated to attainment, CAA section 175A(b) requires the 
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State to submit a subsequent maintenance plan to the EPA, covering a second 10-year period.1

The second maintenance plan must demonstrate continued compliance with the NAAQS during 

this second 10-year period. To fulfill this requirement of the CAA, Arizona submitted the second 

10-year update of the Phoenix area CO maintenance plan to the EPA on April 2, 2013. The plan 

was developed by the Maricopa Association of Governments (MAG) and is titled “MAG 2013 

Carbon Monoxide Maintenance Plan for the Maricopa County Area” (hereinafter, “2013 

Maintenance Plan”). MAG is the State’s delegated Agency with authority to develop SIPs for 

Maricopa County. With this action, we are proposing to approve the 2013 Maintenance Plan as a 

revision to the Arizona SIP.

C. Transportation Conformity

Section 176(c) of the Act defines conformity as meeting the SIP's purpose of eliminating 

or reducing the severity and number of violations of the NAAQS and achieving expeditious 

attainment of such standards. The Act further defines transportation conformity to mean that no 

Federal transportation activity will: (1) Cause or contribute to any new violation of any standard 

in any area; (2) increase the frequency or severity of any existing violation of any standard in any 

area; or (3) delay timely attainment of any standard or any required interim emission reductions 

or other milestones in any area. The Federal transportation conformity rule, 40 CFR part 93 

subpart A, sets forth the criteria and procedures for demonstrating and assuring conformity of 

transportation plans, programs and projects which are developed, funded or approved by the U.S. 

Department of Transportation, and by metropolitan planning organizations or other recipients of 

 1 In this case, the initial maintenance period extended through 2015. Thus, the second 10-year period extends 

through 2025.
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Federal funds under Title 23 U.S.C. or the Federal Transit Laws. 49 U.S.C. chapter 53.

The transportation conformity rule applies within all nonattainment and maintenance 

areas. As prescribed by the transportation conformity rule, once an area has an applicable SIP 

with MVEBs, the expected emissions from planned transportation activities must be consistent 

with such established budgets for that area.

With this action, the EPA proposes to find adequate and approve a CO transportation 

conformity MVEB for the year 2025 and beyond.

II. The EPA’s Evaluation of Arizona’s Submittal

The 2013 Maintenance Plan contains the following major sections:

1. Introduction. This section contains a general discussion of CO plan approvals and the 

area’s redesignation to attainment. 2013 Maintenance Plan, Chapter 1.

2. Continued Attainment of the Carbon Monoxide NAAQS. This section includes some 

historical background, a description of the CO monitoring network in Phoenix, monitoring 

results and the State’s demonstration that the area has continued to attain the CO standards, and 

information regarding the State’s monitoring data quality assurance program. 2013 Maintenance 

Plan, Chapter 2.

3. Maintenance Plan. This section includes control measures, maintenance demonstration, 

monitoring network information and verification that the area has continued to attain the CO 

standards, contingency provisions, a transportation conformity budget and subsequent 

maintenance plan revisions. 2013 Maintenance Plan, Chapter 3.

The following is the EPA’s evaluation of the ambient air monitoring information and 

maintenance plan provided in the State’s submittal.
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A. Ambient Air Quality Monitoring Data

The primary NAAQS for CO are: “(1) 9 parts per million (10 milligrams per cubic meter) 

for an 8-hour average concentration not to be exceeded more than once per year and (2) 35 parts 

per million (40 milligrams per cubic meter) for a 1-hour average concentration not to be 

exceeded more than once per year.” 40 CFR 50.8. At the time of submittal of the 2013 

Maintenance Plan in March 2013, there had been no violations in Phoenix of the 1-hour carbon 

monoxide standard since 1984 and no violations of the 8-hour standard since 1996. 2013 

Maintenance Plan, page 1-1.

Table 1 – CO Design Values for Phoenix, AZ, years 2005-2014

Design Values (ppm)2

Years

1-Hour 8-Hour

7.0 4.6 2005

6.5 4.6 2006

6.0 4.1 2007

4.5 3.0 2008

4.8 3.3 2009

8.9 3.2 2010

3.9 2.9 2011

4.5 2.5 2012

4.2 2.7 2013

4.9 2.8 2014

The EPA also examined monitoring data for Phoenix from the entire period covered by 

the first maintenance plan. Table 1 shows the complete, quality assured and certified ambient air 

monitoring design values for CO in the area for the years 2005 to 2014. The monitoring data 

show the area has not violated the CO standards during the first maintenance period. The EPA 

 2 Design values were derived from the EPA Air Trends (http://www3.epa.gov/airtrends/values.html) website.
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notes the trend of 8-hour CO design values decreasing during this period, as also described in the 

2013 Maintenance Plan for the years 2004 to 2011. 2013 Maintenance Plan, figure 2-2, page 2-8.

B. Maintenance Plan Control Measures

The State and MAG commit to continue to implement the nine control measures listed in 

the 2003 Maintenance Plan, and have implemented a tenth control measure that had been 

identified in that plan as a contingency measure. 2013 Maintenance Plan, page 3-1. Table 2 lists 

these control measures. 2013 Maintenance Plan, table 3-1, page 3-2.

Table 2 – Maintenance Measures in the 2013 Maintenance Plan

1. California Phase 2 Reformulated Gasoline with 3.5% Oxygen Content from November 

1 through March 31

2. Off-Road Vehicle and Engine Standards

3. Phased-in Emission Test Cutpoints

4. One-Time Waiver from Vehicle Emissions Test

5. Defer Emissions Associated with Government Activities

6. Coordinate Traffic Signal Systems

7. Develop Intelligent Transportation Systems

8. Tougher Enforcement of Vehicle Registration and Emissions Test Compliance

9. Clean Burning Fireplace Ordinances

10. Expansion of Area A Boundaries

The tenth control measure listed in Table 2 is described in the 2003 Maintenance Plan as 

a contingency measure. 2003 Maintenance Plan, Exhibit 2, Appendix A, Technical Support 
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Document, Section VII-2-2. The State has implemented the expansion of Area A boundaries and

the EPA approved the expansion of Area A boundaries as a revision to the Arizona SIP on May 

22, 2013. 78 FR 30209.

C. Emissions Inventories

The 2013 Maintenance Plan provides a comparison of actual CO emissions in the 

Phoenix maintenance area in 2008 with projected emissions in 2025. 2003 Maintenance Plan, 

page 3-4, table 3-3. These emissions are for an average weekday during the winter season, the 

months November to January. The 2008 emissions are taken from the latest periodic emissions 

inventory for the area, the 2008 periodic emissions inventory, which is included in Appendix A, 

Exhibit 1 of the 2013 Maintenance Plan. Emissions for the year 2025 used growth factors for the 

area derived from the 2005 special U.S. census conducted in the area and EPA models for 

estimating onroad emissions and nonroad equipment emissions, as well as the Emissions and 

Dispersion Modeling System and the Federal Aviation Administration Terminal Area Forecast 

system database for all airports except Luke Air Force Base (AFB). Emissions of CO from the 

Luke AFB were derived from two documents: the first, titled “2008 Mobile Source Emissions 

Inventory for Luke Air Force Base,” prepared by Weston Solutions, Inc. for the Air Education 

and Training Command, U.S. Air Force, Randolph AFB, Texas, in June 2010; the second 

document is titled “F-35A Training Basing Environmental Impact Statement, Final Volume 1,” 

prepared by the U.S. Air Force in 2012.

Several emissions reductions are credited in the projected emissions for the year 2025.

The first two control measures listed in Table 2, California Phase 2 Reformulated Gasoline with 

3.5 percent Oxygen Content from November 1 through March 31, and Off-Road Vehicle and 
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Engine Standards, are estimated to produce reductions of CO emissions of 128.9 mtpd and 15 

mtpd, respectively. These reductions represent about a 19 percent reduction of emissions by 

2025. The State and MAG commit to continued implementation of all other control measures 

listed in Table 2. However, their collective reduction is expected to be less than one percent of 

2025 emissions, and therefore no numeric credit was taken for those measures in the State’s 

projections of CO emissions in 2025.

Details regarding the technical inputs and assumptions used in preparing the emissions 

inventories are provided in Chapter II of the technical support document for the 2013 

Maintenance plan, in Appendix A, Exhibit 2. The results of MAG’s inventory of actual 

emissions in 2008 and projected emissions in 2025 are provided in Table 3.

Table 3 – Average Weekday Emissions during the Winter Season in the Phoenix CO 

Maintenance Area, in metric tons per day (mtpd)

Source Category

CO Emissions

2008 2025

Point 0.7 19.8

Area 37.8 47.3

Nonroad 281.5 213.1

Onroad 581.6 359.4

TOTAL 901.6 639.6

Compared to emissions in 2008, projected emissions in 2025 show a downward trend.

Total CO emissions projected in the year 2025, 639.6 mtpd, represent approximately 70 percent 
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of the actual emissions in the year 2008.

D. Maintenance Demonstration

The 2013 Maintenance Plan relies on a series of technical analyses to demonstrate 

maintenance of the CO NAAQS through the year 2025. MAG performed three different 

modeling analyses to project CO emissions out to the year 2025 and estimate their impact on 

maximum ambient CO concentration. In addition, MAG conducted two weight-of-evidence 

evaluations using actual trends in air quality and meteorological data to reinforce the modeling 

analyses. MAG also developed a modeling protocol to detail the technical approaches and 

assumptions to be used in demonstrating maintenance of the CO NAAQS. 2013 Maintenance 

Plan, Appendix A, Exhibit 2, Technical Support Document.

MAG’s first modeling analysis was based on an emissions inventory comparison. MAG

developed two sets of CO emissions inventories: one representing the CO modeling domain in 

2006, 2008, 2015 and 2025; another representing the maintenance area in 2008 and 2025. The 

modeling domain covers 792 square miles, including the busiest intersections in the area and the 

ambient air monitors with the highest readings, while the maintenance area is 1,814 square miles.

MAG calculated the ratio of the total emissions expected in 2025 to the total emissions in a prior 

year (2006 for the modeling domain and 2008 for the maintenance area). MAG then multiplied 

these ratios by the maximum concentration in the earlier year to yield a predicted 2025 

concentration. The maximum 8-hour CO concentration at West Indian School monitor in 2006 

was 5.3 ppm. When multiplied by the ratio of 2025 emissions for the maintenance area (403.9 

mtpd) divided by 2006 emissions (803.0 mtpd) for the maintenance area, or 0.503, the predicted 

concentration in 2025 at the West Indian School monitoring site is 2.7 ppm, well below the 9
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ppm level of the 8-hour CO NAAQS.

MAG’s second modeling analysis involved updating the modeling of CO concentrations 

performed in the 2003 Maintenance Plan using the EPA-approved Urban Airshed Model (UAM) 

and the intersection hotspot model (CAL3QHC). In particular, MAG updated the projections of 

concentrations for the years 2006 and 2015 in the 2003 Maintenance Plan by adjusting by the 

ratio of new to old emissions inventory totals and then scaling them for the year 2025. The 

highest concentrations in 2025 predicted at the two busiest intersections in Phoenix (at the 

Phoenix Grand Avenue and West Indian School monitors) using these models was 4.0 ppm, less 

than half of the level of the 8-hour standard.

MAG’s third modeling approach in the 2013 Maintenance Plan was an intersection 

hotspot analysis. The three intersections projected to have the highest traffic volumes and the 

three intersections projected to have the worst traffic congestion were identified using the MAG

TransCAD traffic assignment for the year 2025. MAG used CAL3QHC to determine the 

maximum 8-hour concentration at these intersections in 2025, then added the expected 

background concentration, 1.3 ppm CO. The highest CO concentration expected in 2025 was 1.7 

ppm at two intersections, 16th Street and Camelback Road, and Priest Drive and Southern 

Avenue. This level is also well below the 8-hour CO NAAQS.

In addition to the above three modeling exercises, MAG conducted two weight-ofevidence evaluations to support the maintenance demonstration. In one, historical trends of 1-

hour and 8-hour monitored CO concentrations were applied to a regression analysis to project 

concentrations in 2015 and 2025. The monitoring data used was from the period 1980 to 2011.

Projecting forward the trend lines using regression analysis for each monitoring site, the West 
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Phoenix site has the highest projected 8-hour CO concentration, 2.7 ppm in 2015 and 1.6 ppm in 

2025.

In a second weight-of-evidence evaluation, MAG conducted a meteorological analysis to 

assess whether unusually favorable meteorology played a role in continued maintenance of the 

CO standard. In particular, MAG assessed long-term values of key meteorological parameters, 

including temperature, wind speed, wind direction, atmospheric stability and mixing height and 

compared these values to CO monitored concentration trends during the same period. Four 

meteorological analyses were performed, comparing later meteorological data to the data from 

the 1994 episode used in the evaluation, when there was an exceedance of the 8-hour CO 

standard, with the following results: 1) the maximum 8-hour CO concentrations have continued 

to decline, while meteorological conditions have not differed significantly from the 1994 

episode; 2) 8-hour CO concentrations declined while daily variations in wind speeds, 

temperatures and mixing heights have not varied significantly over time; 3) 1-hour CO 

concentrations have continued to decrease over time regardless of meteorological conditions; and 

4) daily maximum 8-hour CO concentrations below the CO NAAQS were predominant during 

the period 1997 through 2011 under the same range of wind speeds and mixing heights.

The EPA finds that the three modeling exercises and two weight-of-evidence evaluations 

provide compelling evidence that the Phoenix area will continue to maintain the CO NAAQS.

E. Ambient Air Quality Monitoring Network

The Phoenix area has maintained an ambient air quality monitoring network consisting of 

twelve State and Local Air Monitoring Stations (SLAMS). Of these twelve monitoring stations, 

11 are operated by the Maricopa County Air Quality Department (MCAQD) and one monitor is 
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operated by the Arizona Department of Environmental Quality (ADEQ). These agencies provide 

the EPA with Annual Monitoring Network Plans (commonly known as Annual Network Plans or 

ANPs) for the area, and have committed to continue to operate an appropriate air quality 

monitoring network in accordance with appendix D of 40 CFR part 58. 2013 Maintenance Plan, 

page 3-17.

The EPA approved the area’s ANPs, which describe the monitoring network for the area 

and any changes anticipated for the following year. The most recent ANP from the MCAQD was 

the “MCAQD 2013 Final Air Monitoring Network Review,” dated December 5, 2014. The most 

recent ANP from ADEQ was the “State of Arizona Air Monitoring Network Plan for the Year 

2014,” dated July 1, 2014. The 2014 MCAQD ANP was approved by the EPA on March 31, 

2015. Letter from Meredith Kurpius, Manager, Air Quality Analysis Office, to William Wiley, 

Director, MCAQD, dated March 31, 2015. The 2014 ADEQ ANP was approved by the EPA on 

October 30, 2014. Letter from Meredith Kurpius, Manager, Air Quality Analysis Office, to Eric 

Massey, Director, Air Quality Division, ADEQ, dated October 30, 2014.

The EPA performs Technical Systems Audits (TSA) of ambient air monitoring programs 

in accordance with 40 CFR part 58, section 2.5, which requires that the EPA conduct TSAs of 

primary quality assurance organizations every three years. The most recent TSA for the MCAQD 

was conducted by the EPA on September 25 to September 27, 2013. The EPA’s findings from 

this TSA are presented in a final report. There were no findings that were cause for data 

invalidation. Letter from Deborah Jordan, Director, U.S. EPA Region 9 Air Division, to Phil 

McNeely, Director, Maricopa County Air Quality Department, dated December 12, 2014, 

transmitting “Technical System Audit, Maricopa County Air Quality Department, Ambient Air 
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Monitoring Program, September 25 – September 27, 2013,” dated December 2014.

The most recent TSA for ADEQ was conducted by the EPA on April 9 to April 13, 2012.

The EPA’s findings from this TSA are presented in a final report. There were no findings that 

were cause for data invalidation. Letter from Deborah Jordan, Director, U.S. EPA Region 9 Air 

Division, to Eric Massey, Director, ADEQ Air Division, dated January 18, 2013, transmitting 

“Technical System Audit, Arizona Department of Environmental Quality, Ambient Air 

Monitoring Program, April 9 – April 13, 2012,” dated January 2013.

The EPA is confident that the area’s air quality monitoring network is being implemented 

in accordance with requirements in the CAA and implementing regulations in 40 CFR part 58.

F. Contingency Plan

Section 175A(d) of the CAA requires that a maintenance plan include contingency 

provisions to promptly correct any violation of the NAAQS that occurs after redesignation of an 

area. A maintenance plan’s contingency measures are not required to be fully adopted. However, 

the plan should contain clearly identified contingency measures to be adopted, a schedule and 

procedure for adoption and implementation, and a specific time limit for action by the State. In 

addition, specific indicators should be identified which will be used to determine when the 

contingency measures need to be implemented. EPA memorandum, “Procedures for Processing 

Requests to Redesignate Areas to Attainment,” September 4, 1992.

Two contingency measures that were included in the 2003 Maintenance Plan are included 

in the 2013 Maintenance Plan: Gross Polluter Option for I/M Program Waivers, and Increased 

Waiver Repair Limit Options. These contingency measures have already been implemented in 

the area. A third contingency measure has been added to the 2013 Maintenance Plan:
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Reinstatement of the Vehicle Emissions Inspection and Maintenance (VEI) Program for 

Motorcycles. The VEI program for motorcycles was a control measure in the area prior to 

redesignation to attainment, but the State subsequently exempted motorcycles from the VEI

program. Pursuant to section CAA section 175A(d) of the CAA, the contingency provisions of a 

maintenance plan must include all the control measures that were included in the SIP for the area 

before redesignation. Therefore, the State is required to include the VEI program for motorcycles

as a contingency measure in the 2013 CO Maintenance Plan. ADEQ has fulfilled this 

requirement by submitting a SIP revision committing to request Legislative action to reinstate 

emissions testing for motorcycles in the Phoenix area should the area experience a violation of 

the CO standards. See 78 FR 30209, May 22, 2013. In addition, as noted above, the State has 

expanded Area A in Maricopa County, which extends additional controls beyond the previous 

boundary for Area A, converting this expansion from a contingency measure in the 2003 

Maintenance Plan, to a control measure in the 2013 Maintenance Plan.

We propose to find that the contingency plan in the 2013 Maintenance Plan is sufficient 

to meet the requirements of section 175A(d) of the CAA.

G. Transportation Conformity

Transportation conformity is required by section 176(c) of the CAA. Conformity to a SIP 

means that transportation activities will not produce new air quality violations, worsen existing 

violations, or delay timely attainment of the NAAQS (CAA section 176(c)(1)(B)). The EPA’s 

conformity rule at 40 CFR part 93, subpart A requires that transportation plans, programs and 

projects conform to SIPs and establish the criteria and procedures for determining whether or not 

they conform. To effectuate its purpose, the conformity rule generally requires a demonstration 
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that emissions from the Regional Transportation Plan (RTP) and the Transportation 

Improvement Program (TIP) are consistent with MVEBs contained in the control strategy SIP 

revision or maintenance plan (40 CFR 93.101, 93.118, and 93.124). An MVEB is defined as the 

level of mobile source emissions of a pollutant relied upon in the attainment or maintenance 

demonstration to attain or maintain compliance with the NAAQS in the nonattainment or 

maintenance area.3 The EPA’s process for determining adequacy of a MVEB consists of three 

basic steps: (1) Notifying the public of a SIP submission; (2) providing the public the 

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

finding of adequacy or inadequacy. See 40 CR 93.118(f). The 2003 Maintenance Plan 

established CO MVEBs (calculated for Friday in December) of 699.7 mtpd in 2006 and 662.9 

mtpd in 2015. The EPA found the CO MVEBs adequate for transportation conformity purposes 

on September 29, 2003, 68 FR 55950, and approved the MVEBs on March 9, 2005, 70 FR 

11553.

The 2013 Maintenance Plan establishes a 2025 MVEB of 559.4 mtpd for the CO

maintenance area. We are not announcing the availability of this MVEB through the EPA’s 

Adequacy Web site and providing a separate comment period on the adequacy of the MVEB. 

Instead, we are reviewing the adequacy of the MVEB simultaneously with our review of the 

2013 Maintenance Plan itself. See 40 CFR 93.118(f)(2). In order to determine whether this 

MVEB is adequate and approvable, we have evaluated whether the MVEB meets the conformity 

adequacy provisions of 40 CFR 93.118(e)(4) and (5). The details of the EPA’s evaluation of the 

 3 Further information concerning the EPA’s interpretations regarding MVEBs can be found in the preamble to the 

EPA’s November 24, 1993, transportation conformity rule (see 58 FR 62193 – 62196).
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MVEB for compliance with the budget adequacy criteria of 40 CFR 93.118(e) are provided in a 

memo to file for this proposed rulemaking. Memo from John J. Kelly, Air Planning Office, EPA 

Region 9, to Docket EPA-R09-OAR-2015-0645, dated September 29, 2015. Based on this 

evaluation, we propose to find the 2025 MVEB adequate and to approve it. Any and all 

comments on the adequacy and approvability of the 2025 MVEB should be submitted during the 

comment period stated in the DATES section of this document.

If today’s proposed action is finalized, the 2015 MVEB, which is already approved for 

2015 and later years, would apply only up to the year 2024. For the year 2025 and later years, the 

budget will be 559.4 mtpd. See Table 4.

Table 4 – Approved and Proposed Transportation Conformity Motor Vehicle Emissions 

Budgets for the Phoenix CO Maintenance Area, in metric tons per day (mtpd)

Approved Approved Proposed

Year 2006 2015 2025

CO MVEB 699.7 662.9 559.4

III. Proposed Action

The EPA is proposing to approve the 2013 Maintenance Plan submitted on April 3, 2012.

This maintenance plan meets the applicable CAA requirements and the EPA has determined it is

sufficient to provide for maintenance of the CO NAAQS over the course of the second 10-year 

maintenance period out to 2025.

The EPA is also proposing to find adequate and approve the CO MVEB of 559.4 mtpd 

for use in the year 2025 and later years.
This document is a prepublication version signed by EPA Regional Administrator Jared Blumenfeld on September 

30, 2015. We have taken steps to ensure the accuracy of this version, but it is not the official version.

19

IV. Statutory and Executive Orders Review

Under the CAA, the Administrator is required to approve a SIP submission that complies 

with the provisions of the Act and applicable federal regulations. 42 U.S.C. 7410(k); 40 CFR 

52.02(a). Thus, in reviewing SIP submissions, the EPA’s role is to approve State choices, 

provided that they meet the criteria of the CAA. Accordingly, this action merely proposes to 

approve State law as meeting federal requirements and does not impose additional requirements 

beyond those imposed by State law. For that reason, this action:

• Is not a "significant regulatory action” subject to review by the Office of Management 

and Budget under Executive Order 12866 (58 FR 51735, October 4, 1993);

• Does not impose an information collection burden under the provisions of the Paperwork 

Reduction Act (44 U.S.C. 3501 et seq.);

• Is certified as not having a significant economic impact on a substantial number of small 

entities under the Regulatory Flexibility Act (5 U.S.C. 601 et seq.);

• Does not contain any unfunded mandate or significantly or uniquely affect small 

governments, as described in the Unfunded Mandates Reform Act of 1995 (Public Law 

104-4);

• Does not have federalism implications as specified in Executive Order 13132 (64 FR 

43255, August 10, 1999);

• Is not an economically significant regulatory action based on health or safety risks 

subject to Executive Order 13045 (62 FR 19885, April 23, 1997); 

• Is not a significant regulatory action subject to Executive Order 13211 (66 FR 28355, 
This document is a prepublication version signed by EPA Regional Administrator Jared Blumenfeld on September 

30, 2015. We have taken steps to ensure the accuracy of this version, but it is not the official version.

20

May 22, 2001); 

• Is not subject to requirements of Section 12(d) of the National Technology Transfer and 

Advancement Act of 1995 (15 U.S.C. 272 note) because application of those 

requirements would be inconsistent with the Clean Air Act; and

• Does not provide the EPA with the discretionary authority to address, as appropriate, 

disproportionate human health or environmental effects, using practicable and legally 

permissible methods, under Executive Order 12898 (59 FR 7629, February 16, 1994).

In addition, the SIP is not approved to apply on any Indian reservation land or in any 

other area where the EPA or an Indian tribe has demonstrated that a tribe has jurisdiction. In 

those areas of Indian country, the rule does not have tribal implications and will not impose 

substantial direct costs on tribal governments or preempt tribal law as specified by Executive 

Order 13175 (65 FR 67249, November 9, 2000).

List of Subjects in 40 CFR Part 52

Environmental protection, Air pollution control, Carbon monoxide, Incorporation by 

reference, Intergovernmental relations, Reporting and recordkeeping requirements. 

Authority: 42 U.S.C. 7401 et seq

September 30, 2015 /s/

__________ ______________________

Dated: Jared Blumenfeld

Regional Administrator

Region 9