UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX 

75 Hawthorne Street 

San Francisco, CA 94105

Memorandum

To: Phoenix, Arizona Carbon Monoxide Second Ten-Year Maintenance Plan SIP Proposed 

Approval Docket, Docket ID EPA-R09-OAR-2015-0645

From: John J. Kelly, Air Planning Office, EPA Region 9

Date: September 29, 2015

RE: Adequacy Documentation for Plan Motor Vehicle Emission Budgets in April 2013

Phoenix CO Maintenance State Implementation Plan (SIP) Submittal

Attached to this memorandum is the adequacy documentation for the Motor Vehicle Emission Budget in 

the plan developed by the Maricopa Association of Governments (MAG), titled MAG 2013 Carbon

Monoxide Maintenance Plan for the Maricopa County Area, Maricopa County, Arizona (April

2013)(“2013 Maintenance Plan”). This maintenance plan is the second ten-year CO maintenance plan 

for the area. EPA approved the first ten-year maintenance plan for the area in 2005.

The 2013 Maintenance Plan was adopted by the Arizona Department of Environmental Quality (ADEQ) 

and submitted to EPA on April 2, 2013. MAG is the State’s delegated Agency with authority to develop 

SIPs for Maricopa County. The 2013 Maintenance Plan identifies a Motor Vehicle Emission Budget 

(MVEB) for the Phoenix CO maintenance area for 2025. We are not announcing receipt of the 2013 

Maintenance Plan on the Internet. Instead, our Federal Register notice of proposed rulemaking for the 

2013 Maintenance Plan will serve to notify the public that EPA is reviewing the implementation plan 

submission for adequacy and will start a public comment period of 30 days. See 40 CFR 93.118(f)(2).

This memo contains our analysis of the MVEB in the 2013 Maintenance Plan for the Phoenix 

maintenance area portion of Maricopa County, Arizona. The budget is listed in the following table, and 

our evaluation of the MVEB is in Table 1, below.

Budget Year CO 

(metric tons per day)

2025 559.4
 

Table 1. Evaluation of the 2025 Motor Vehicle Emissions Budget in the 

Phoenix Maintenance Area Second Ten-Year Maintenance Plan (April 2013)

September 2015 (reviewed by John J. Kelly)

Adequacy Review Criteria

(40 CFR part 93)

Is Criterion

Satisfied? Reference in SIP Document/Comments

Sec. 

93.118(e)(4)(i)

The plan was endorsed by the 

Governor (or designee) and was 

subject to a public hearing.

Y

The 2013 Maintenance Plan was submitted to EPA on April 2, 2013 by Eric 

Massey, Director, ADEQ Air Quality Division, the Governor of 

Arizona’s designee for all SIP revision submittals. The SIP was developed by the 

Maricopa Association of Governments (MAG). This SIP submittal documents that 

MAG, which is responsible under Arizona law for SIP development within the 

boundaries of Maricopa County, Arizona, adopted the plan on March 27, 2013. 

2013 Maintenance Plan, Appendix B, Exhibit 2, Certification of Adoption. MAG 

held a public hearing on the plan on February 19, 2013. 2013 Maintenance Plan, 

Appendix B, Exhibit 1, Public Hearing Process Documentation.
 

Table 1. Evaluation of the 2025 Motor Vehicle Emissions Budget in the 

Phoenix Maintenance Area Second Ten-Year Maintenance Plan (April 2013)

September 2015 (reviewed by John J. Kelly)

Adequacy Review Criteria

(40 CFR part 93)

Is Criterion

Satisfied? Reference in SIP Document/Comments

Sec. 

93.118(e)(4)(ii)

The plan was developed through 

consultation with federal, state 

and local agencies; full 

implementation plan 

documentation was provided and 

EPA’s stated concerns, if any, 

were addressed.

Y

Regarding consultation, MAG developed the 2013 Maintenance Plan in 

consultation with Federal, State, and local agencies. These agencies include: EPA 

Region IX; Federal Highway Administration; Federal Transit Administration; 

Arizona Department of Transportation; Arizona Department of Environmental 

Quality (ADEQ), Air Quality Division; and other State and Local entities. Letter 

to above parties from Lindy Bauer, Environmental Director, MAG, subject 

“Transmittal of the draft MAG 2013 Carbon Monoxide Maintenance Plan for the 

Maricopa County Area,” dated January 18, 2013, 2013 Maintenance Plan, 

Appendix B, Exhibit 1, Public Hearing Process Documentation. See also, MAG 

1992 interagency consultation memorandum of agreement, “Air Quality 

Memorandum of Agreement.”

MAG also consults on SIPs with the MAG Air Quality Technical Advisory 

Committee, composed largely of parties external to MAG. The TAC consists of 

representatives from MAG member agencies; citizens; environmental interests; 

health interests; construction firms; utilities; public transit; architecture; 

agriculture; the business community; the automobile, fuel, trucking, rock products, 

and housing industries; parties to the Air Quality Memorandum of Agreement, and 

various state and federal agencies.

Regarding addressing EPA’s concerns, the EPA was afforded the opportunity to 

comment on the draft plan and provided comments which were addressed in the 

plan’s public participation section. 2013 Maintenance Plan, Appendix B, Exhibit 

1, Public Hearing Process Documentation.
 

Table 1. Evaluation of the 2025 Motor Vehicle Emissions Budget in the 

Phoenix Maintenance Area Second Ten-Year Maintenance Plan (April 2013)

September 2015 (reviewed by John J. Kelly)

Adequacy Review Criteria

(40 CFR part 93)

Is Criterion

Satisfied? Reference in SIP Document/Comments

Sec. 

93.118(e)(4)(iii)

The motor vehicle emission 

budgets are clearly identified and 

precisely quantified.

Y

The MVEB is clearly identified and precisely quantified for the year 2025. In the 

plan’s Table 3-3, “Average Weekday Emissions During the Winter Season in the 

Carbon Monoxide Maintenance Area,” CO emissions are provided in metric tons 

per day for Point, Area, Non-road, and On-road source categories. Emissions 

numbers are provided for a model year, 2008, and the relevant projected future 

year for the maintenance plan, the last year of the ten-year duration of the plan, the 

year 2025. A safety margin of 90% of the difference between the 2008 and 2025 

CO emissions (200 mtpd) was added to the on-road emissions projected in 2025 to 

derive the 2025 MVEB. The 2025 MVEB provided in the plan is 559.4 mtpd. 

2013 Maintenance Plan, Transportation Conformity Budget section, page 3-22. 

Sec. 

93.118(e)(4)(iv)

The motor vehicle emissions 

budget(s), when considered 

together with all other emission 

sources, is consistent with 

applicable requirements for

reasonable further progress, 

attainment, or maintenance

(whichever is relevant to a given 

implementation plan submission).

Y

The 2013 Maintenance Plan describes how the MVEB, when considered together 

with all other emission sources, is consistent with maintenance of the CO NAAQS

in the Phoenix metropolitan area through 2025. The 2025 MVEB is less than the 

MVEBs for previous years, and when taken together with other source categories, 

the total CO emissions for the maintenance area are projected to decline from 

901.6 mtpd in 2008 to 639.6 mtpd in 2025. 2013 Maintenance Plan, Table 3-3, 

“Average Weekday Emissions During the Winter Season in the Carbon Monoxide 

Maintenance Area,” page 3-4.

Sec. 

93.118(e)(4)(v)

The plan shows a clear 

relationship among the emissions 

budget(s), control measures and 

the total emissions inventory.

Y

The 2013 Maintenance Plan includes an emissions inventory section that includes 

modeled MVEBs and a detailed discussion of control measures. Control measures 

are listed in order of the amount of emissions reductions they achieve, and the plan 

clearly indicates which of the control measures were credited with reductions. 
 

Table 1. Evaluation of the 2025 Motor Vehicle Emissions Budget in the 

Phoenix Maintenance Area Second Ten-Year Maintenance Plan (April 2013)

September 2015 (reviewed by John J. Kelly)

Adequacy Review Criteria

(40 CFR part 93)

Is Criterion

Satisfied? Reference in SIP Document/Comments

Sec. 

93.118(e)(4)(vi)

Revisions to previously submitted 

control strategy or maintenance 

plans explain and document any 

changes to any previous 

submitted budgets and control 

measures; impacts on point and 

area source emissions; any 

changes to established safety 

margins (see §93.101 for 

definition), and reasons for the 

changes (including the basis for 

any changes to emission factors or 

estimates of vehicle miles 

traveled).

Y

EPA approved the 2003 Maintenance Plan in 2005. The 2013 Maintenance Plan is 

the required second maintenance plan for the area. Where the first plan had 

MVEBs for 2006 and 2015, the second added the last year of the plan period, the 

year 2025. The 2013 Maintenance Plan clearly indicates changes to control 

measures. It details the deletion of the VEI program for motorcycles, a previous 

control measure, which took place in a separate EPA action, and the addition of a 

contingency measure under the 2003 plan, “Expansion of Area A Boundaries,” as 

an implemented control measure under the 2013 plan. The VEI exemption for 

motorcycles is also presented in the 2013 plan as a contingency measure. 2013 

Maintenance Plan: Maintenance Plan Control Measures section; Emissions 

Inventories section; Technical Support Document, Appendix A, Exhibit 2, section 

IV-6, page IV-38, “Transportation Conformity Budget.”

Sec. 

93.118(e)(5)

EPA has reviewed the State’s 

compilation of public comments 

and response to comments that are 

required to be submitted with any 

implementation plan.

Y

A notice of the initial public comment period and hearing on the 2013 Maintenance 

Plan was published in The Arizona Republic on January 18, 2013. A hearing on the 

plan was held on February 19, 2013. The only public comments MAG received on 

the draft maintenance plan regarded the area’s monitoring network. MAG 

responded to the comments by describing monitoring program requirements. No 

other adverse comments were made at the public hearing from members of the 

public. The 2013 Maintenance Plan submittal includes a copy of EPA’s comments 

on the draft plan and MAG’s response to those comments. 2013 Maintenance Plan, 

Appendix B, Exhibit 1, Public Hearing Process Documentation.