UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

REGION X 

1200 6th Avenue 

Seattle, Washington 98101 

Technical Support Document (TSD) - Adequacy Findings for the Motor Vehicle 

Emissions Budgets in the 2006 Fine Particulate Matter (PM2.5) National Ambient 

Air Quality Standard (NAAQS) Maintenance Plan for the Tacoma-Pierce County 

(WA) 2006 PM2.5 Nonattainment Area 

Submitted November 2014

I. Background 

On November 13, 2009 (74 FR 58688), the Environmental Protection Agency (EPA) published air quality 

area designations for the 2006 PM2.5 NAAQS. In that rulemaking action, EPA designated parts of 

Tacoma-Pierce County (the Area), nonattainment for the 2006 24-hour PM2.5 standard. On September 4, 

2012 (77 FR 53772), EPA determined that the Area had clean data for the 2006 PM2.5 NAAQS based on 

quality-assured, quality-controlled and certified ambient air monitoring data that showed the Area had

monitored attainment based on 2009 through 2011 data. 

II. Transportation Conformity Requirements 

Transportation conformity is required under section 176(c) of the Clean Air Act (CAA) to ensure that 

federally supported highway, transit projects, and other activities are consistent with (conform to) the 

purpose of the State Implementation Plan (SIP). The CAA requires federal actions in nonattainment and 

maintenance areas1

 to "conform to" the goals of SIP. This means that such actions will not cause or 

contribute to violations of a NAAQS; worsen the severity of an existing violation; or delay timely 

attainment of any NAAQS or any interim milestone. 

Actions involving Federal Highway Administration (FHWA) or Federal Transit Administration 

(FTA) funding or approval are subject to the Transportation Conformity Rule (40 CFR part 93, subpart 

A). Under this rule, metropolitan planning organizations (MPOs) in nonattainment and maintenance areas

coordinate with state air quality and transportation agencies, EPA, FHWA, and FTA to demonstrate that 

their metropolitan transportation plans and transportation improvement plans (TIPs) conform to 

applicable SIPs. This is typically determined by showing that estimated emissions from existing and 

planned highway and transit systems are less than or equal to the MVEBs contained in a SIP. 

For MVEBs to be approvable, they must meet, at a minimum, EPA's adequacy criteria found at 

40 CFR 93.118(e)(4). EPA's adequacy criteria are: (1) the submitted control strategy implementation plan 

was endorsed by the Governor or designee and was subject to a State public hearing; (2) consultation 

among Federal, State, and local agencies occurred; full implementation plan documentation was provided 

to EPA; and EPA's stated concerns, if any, were addressed before the control strategy implementation 

plan was submitted; (3) the MVEBs are clearly identified and precisely quantified; (4) the MVEBs, when

considered together with all other emissions sources, are consistent with applicable requirements for 

maintenance; (5) the MVEBs are consistent with and clearly related to the emissions inventory and the 

control measures in the submitted control strategy implementation plan; and (6) revisions to previously 

submitted maintenance plans explain and document any changes to previously submitted budgets and 

control measures; impacts on point and area source emissions; any changes to established safety margins; 

 

1

 The term “maintenance area” is used throughout this document to refer to a nonattainment area that 

redesignated back to attainment with an approved state implementation plan demonstrating continued 

maintenance of the NAAQS. 
and reasons for the changes (including the basis for any changes related to emission factors or estimates 

of vehicle miles traveled). 

III. Review of the Submitted Modeling Utilizing the Motor Vehicle Emission Simulator 

(MOVES) 

The Washington Department of Ecology (Ecology) utilized MOVES2010b to produce MVEBs for years 

2017 and 2026. To utilize the MOVES2010b model, a combination of data from the default database 

(version 20100410) and data from local sources were used by Ecology to develop the budgets.

The EPA released MOVES2014 on October 7, 2014 (79 FR 60343). The release indicates that 

MOVES2014 should be used for all SIP development moving forward. However, the release does 

indicate that “...state and local agencies that have already completed significant work on a SIP with a 

version of MOVES2010 (e.g., attainment modeling has already been completed with MOVES2010) can 

continue to do so.” Because Ecology had nearly completed the development of their Maintenance Plan at 

that point, they were not required to use MOVES2014 in the setting of these MVEBs. 

EPA reviewed the modeling methodology utilized by Ecology and all modeling related information to 

produce the MVEBs for years 2017 and 2026, provided in Appendices A through C of the Maintenance 

Plan. EPA found that all necessary and required modeling procedures were followed in the production of

the 2017 and 2025 MVEBs which were produced using MOVES2010b. 

IV. Administrative Requirements for Making Adequacy Findings 

EPA followed the process for determining the adequacy of the submitted SIP MVEBs in accordance with 

the procedures listed in the Conformity Regulations contained in 40 CFR part 93.118(f) "Adequacy 

review process for implementation plan submissions." 

A notice will be posted on EPA's web site located at: 

http://www.epa.gov/otaq/stateresources/transconf/currsips.htm, for the purpose of opening EPA's 

30-day public comment period on the adequacy of the budgets in the Maintenance Plan for the TacomaPierce County, WA 2006 24-hour PM2.5 Nonattainment Area. The purpose of the notice is to inform the 

public of the availability of the Tacoma-Pierce County Maintenance Plan on its own website. EPA's 

website notice provides a link where interested members of the public could access the SIP revision. 

Following EPA's public comment period, responses to any comments received on the proposed mobile 

budgets will be addressed in an amendment to this TSD. 

This TSD will be an enclosure to the letter from EPA to Ecology informing them of EPA's findings on the 

MVEBs within the Tacoma-Pierce County Maintenance Plan. EPA will publish a Federal Register notice 

announcing the adequacy findings. The effective date of the adequacy findings will be 15 days after the 

publication date of that notice. Once EPA has published the Federal Register notice, the letter sent to 

Ecology and this TSD will also be posted at the EPA website. 

Shown in Table 1 are the budgets from the Tacoma-Pierce County Maintenance Plan. Upon the effective 

date of EPA’s approval, the MVEBs in Table 1 for milestone year 2017 and the out-year 2026 for PM2.5 

and NOx will be applied to all future transportation conformity determinations and analyses for the 2006 

24-hour PM2.5 NAAQS. 

Table 1. On-Road MVEBs Contained in the Tacoma-Pierce County Maintenance Plan for the 

2006 24-hour PM2.5 NAAQS (pounds per winter day) 

Year PM2.5 NOx 

2017 1,888 41,790 
2026 1,321 22,880 

V. Evaluation of the Adequacy of the MVEBs in the Tacoma-Pierce County Maintenance Plan for 

the 2006 24-hour PM2.5 NAAQS 

In this TSD, we are evaluating the MVEBs associated with the Tacoma-Pierce County Maintenance Plan 

for conformity purposes. We are using the evaluation criteria detailed in the Transportation 

Conformity Rule part 93, specifically 40 CFR part 93.102(b)(2)(iv), 93.102(b)(2)(v), 93.102(b)(3), and

93.118(e)(4) through 93.118(e)(5). The evaluation is presented in Table 2, below. 

Table 2. Adequacy of the MVEBs Contained in the Tacoma-Pierce County Maintenance Plan for the 

2006 24-hour PM2.5 NAAQS 

Transportation Conformity 

Rule Section 

Applicability/Review Criteria Was the applicability requirement 

met? OR Was the Criterion Satisfied? 

If yes, how was this criteria satisfied? 

93.102(b)(2)(iv) Does the SIP establish MVEBs 

for the applicable pollutants - 

NOx and direct mobile PM2.5 

emissions? 

Yes. The maintenance plan addresses 

both of these pollutants. Neither the 

EPA nor the state have made an 

insignificance finding for either of 

these pollutants. 

93.102(b)(2)(v) Are VOCs, Sulfur Oxides 

(SOx) and Ammonia (NH3) 

considered insignificant 

contributors to the mobile 

PM2.5 emissions? 

Yes. Neither EPA nor the State have 

made any findings that VOCs, SOx, or 

NH3 are significant contributors to the 

PM2.5 mobile emissions, and 

therefore, they have not been included 

in the SIP.

93.102(b)(3) Has the EPA or the State 

made a finding that reentrained 

road dust is a significant 

contributor to the PM mobile 

emissions?

Yes. Neither EPA nor the State have 

made such a finding. 

93.118(e)(4)(i) Was the submitted revised 

plan endorsed by the Governor 

(or his or her designee) and 

subject to a State public 

hearing?

Yes. This plan was filed by the 

Governor of Washington’s designee, 

Maia D. Bellon, Director of the 

Washington State Department of 

Ecology (Ecology), and received on 

November 3, 2014. The plan was the 

subject of a public hearing held in 

Tacoma, WA on September 30, 2014. 

The certificate of hearing is located in 

the Response to Comments Appendix 

F supplied by Ecology, dated October 

2014. 

93.118(e)(4)(ii) Before the maintenance plan 

was submitted to EPA, did 

consultation between federal, 

state and local agencies occur; 

Yes. A draft of the Tacoma-Pierce 

County Maintenance Plan and 

supporting documentation was 

reviewed by EPA Region 10 and 
was full implementation plan 

documentation provided to 

EPA, and were EPA’s stated 

concerns, if any, addressed? 

discussed with Ecology, the Puget 

Sound Regional Council (PSRC), and 

the Puget Sound Clean Air Agency 

(PSCAA) prior to state adoption by 

Ecology on April 29, 2014. In 

addition, informal consultations 

between EPA, Ecology, PSRC, and 

PSCAA were held as the draft plan 

was being developed. EPA concerns 

were addressed during this 

consultation process. 

93.118(e)(4)(iii) Was the motor vehicle 

emission budget(s) clearly 

identified and precisely 

quantified? 

Yes. Section 5 of the maintenance plan 

clearly establishes budgets for PM2.5 

and NOx. Documentation is provided 

both in this section and in Appendix C. 

93.118(e)(4)(iv) Is the motor vehicle emissions 

budget(s), when considered 

together with all other 

emission reductions, consistent 

with applicable requirements 

for maintenance? 

Yes. EPA believes the budgets can be 

declared adequate because in 

conjunction with the other emission 

reductions, they demonstrate continued 

maintenance for years 2017 and 2026. 

93.118(e)(4)(v) Is the motor vehicle emissions 

budget(s) consistent with and 

clearly related to the emissions 

inventory and the control 

measures in the plan? 

Yes. EPA believes that the budgets are 

clearly related to the emissions 

inventory and the control measures in 

the SIP submittal. 

93.118(e)(4)(vi) Revisions to previously 

submitted attainment 

demonstrations: explain and 

document any changes to 

previously 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 related to emission 

factors or estimates of vehicle 

miles traveled). 

Not applicable. The Tacoma-Pierce 

Maintenance Plan provides new 

MVEBs for years 2017 and 2026 for 

PM2.5 and NOx. The addition of 

safety margins to the MVEB is 

consistent with continued attainment. 

93.118(e)(5) Did they provide and we 

review public comments and 

the state’s responses to those 

Yes. The State submitted a complete 

list of comments received during their 
comments with the submitted 

control strategy SIP? 

comment period, as well as the 

response to comments. 

VI. Findings 

Based upon our review and evaluation of the MVEBs contained in the Maintenance Plan for the 

Tacoma-Pierce County, WA 2006 24-hour PM2.5 NAAQS Nonattainment Area, EPA finds the MVEBs 

adequate for conformity purposes.