1

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION III

1650 Arch Street

Philadelphia, Pennsylvania 19103

 

SUBJECT:

 June 17, 2013

Supplemental Technical Support Document (TSD) - Insignificance Findings for the 

Motor Vehicle Emissions for the Redesignation Request and Maintenance Plan for 

the West Virginia Portion of the Parkersburg-Marietta, WV-OH 1997 Fine 

Particulate Matter (PM2.5) Nonattainment Area 

FROM:

 /s/

Gregory Becoat

Environmental Scientist (3AP30)

TO: Administrative Record for the Insignificance Findings for the Motor Vehicle 

Emissions for the Redesignation Request and Maintenance Plan for West Virginia 

Portion of the Parkersburg-Marietta, WV-OH 1997 PM2.5 Nonattainment Area 

THRU:

 /s/

Cristina Fernandez, Associate Director

Office of Air Program Planning (3AP30)

I. Background

On March 8, 2012, the State of West Virginia formally submitted a Redesignation Request and 

Maintenance Plan for West Virginia Portion of the Parkersburg-Marietta, WV-OH 1997 PM2.5

Nonattainment Area (hereafter the Redesignation Request and Maintenance Plan). The State 

Implementation Plan (SIP) included a request for a finding of insignificance by EPA for motor 

vehicle emissions for nitrogen oxides (NOx), direct particulate matter (PM), and sulfur dioxide 

(SO2).

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 SIP. The CAA requires federal actions in nonattainment and 

maintenance areas to “conform to” the goals of SIP. This means that such actions will not cause 

or contribute to violations of a national ambient air quality standard (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 
2

agencies, EPA, FHWA, and FTA to demonstrate that their metropolitan transportation plans and 

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 

motor vehicle emissions budgets (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; and reasons for the changes (including the basis for any changes related to emission 

factors or estimates of vehicle miles traveled).

In certain instances, the Transportation Conformity Rule allows areas to forgo establishment of a 

MVEB where it is demonstrated that the regional motor vehicle emissions for a particular 

pollutant or precursor are an insignificant contributor to the air quality problem in an area. The 

general criteria for insignificance determinations can be found in 40 CFR 93.109(f). 

Insignificance determinations are based on a number of factors, including the percentage of 

motor vehicle emissions in the context of the total SIP inventory; the current state of air quality

as determined by monitoring data for the relevant NAAQS; the absence of SIP motor vehicle 

control measures; and the historical trends and future projections of the growth of motor vehicle 

emissions. EPA’s rationale for providing for insignificance determinations is described in the 

July 1, 2004, revision to the Transportation Conformity Rule at 69 FR 40004. Specifically, the 

rationale is explained on page 40061 under the subsection XXIII.B. entitled, “Areas With 

Insignificant Motor Vehicle Emissions.” Any insignificance determination under review of EPA 

is subject to the adequacy and approval process for EPA's action on the SIP.

II. Administrative Requirements for Making Insignificance Findings 

EPA has followed the process for reviewing the submitted SIP and determining if an

insignificance finding for motor vehicle emissions is warranted in accordance with the 

procedures listed in the January 2008 Conformity Regulations contained in 40 CFR 93.102(b) -

“Geographical applicability” and 40 CFR 93.118(f) - “Adequacy review process for 

implementation plan submissions.”

III. Evaluation of the Request for an Insignificance Finding for Motor Vehicle Emissions 

in the Redesignation Request and Maintenance Plan for the West Virginia Portion of the 
3

Parkersburg-Marietta, WV-OH 1997 PM2.5 Nonattainment Area Submitted by The West 

Virginia Department of Environmental Protection

In this TSD, EPA is evaluating the West Virginia Department of Environmental Protection’s 

request for an insignificance finding for motor vehicle emissions associated with the 

Redesignation Request and Maintenance Plan contained in the submittal. EPA is using the 

evaluation criteria detailed in the Transportation Conformity Rule, 40 CFR 93.102(b)(2)(iv),

(b)(2)(v), and (b)(3) and 93.118(e)(4) and (e)(5). The evaluation is presented below.

Review of the Request for Insignificance Finding of Motor Vehicle Emissions in the

Redesignation Request and Maintenance Plan for the West Virginia Portion of the 

Parkersburg-Marietta, WV-OH PM2.5 Nonattainment Area 

Transportation Conformity Rule

40 CFR Part 93

Review Criteria Was the Criterion Satisfied? If 

Yes, How was this Criteria 

Satisfied?

93.102(b)(2)(iv) Has the EPA and the State 

made a finding that NOx is 

an insignificant contributor 

to the direct mobile PM 

emissions or does the

implementation plan fail to 

establish a NOx budget as 

part of the PM2.5

maintenance strategy?

The State has requested that NOx 

be found an insignificant 

contributor to the mobile PM 

emissions. This request is based 

on the State finding that Onroad 

mobile source NOx constitutes 

less than twelve percent of the 

area’s total NOx emissions in the 

2015 and 2022 horizon years due 

to continuing fleet turnover even 

with future vehicle miles traveled 

(VMT) growth included in the 

emission projections. EPA has 

also made a finding that the 

transportation-related emissions of 

NOx within the nonattainment 

area are not a significant 

contributor to the direct mobile 

PM emissions.

93.102(b)(2)(v) Has the EPA or State made a 

finding that the precursors, 

Volatile Organic Compounds 

(VOCs), SO2 or Ammonia 

(NH3) are a significant 

contributor to the mobile PM 

emissions or does the

implementation plan 

submission establish a 

budget for VOCs, SOx or 

Neither EPA nor the State has

made any findings that VOCs, 

SO2, or NH3 is a significant 

contributor to the PM2.5 mobile 

emissions, and therefore, it has 

not been included in the SIP. 

Onroad mobile source SO2

emissions constitute less than 

0.1% of the area’s total SO2

emissions in the 2015 and 2022 
4

NH3 as part of a PM2.5 

maintenance strategy?

horizon years.

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

made a finding that direct 

PM is a significant 

contributor to the PM mobile 

emissions or does the 

implementation plan 

establish a budget that 

includes direct PM as part of 

a PM 2.5 maintenance 

strategy?

The State has requested that direct 

PM be found an insignificant 

contributor to the mobile PM 

emissions. This request is based 

on the State finding that Onroad 

mobile source PM2.5 constitutes

less than 2.1% of the area’s total 

PM2.5 emissions in the 2015 and 

2022 horizon years due to 

continuing fleet turnover even 

with future VMT growth included 

in the emission projections. 

Sec. 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. The submitted 

Redesignation Request and 

Maintenance Plan was endorsed 

and submitted as a SIP revision by

the Governor’s designee, the 

Secretary of the West Virginia

Department of Environmental 

Protection. A public hearing on 

the SIP proposal was held on 

February 23, 2012. 

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

was submitted to EPA, did 

consultation between federal, 

State and local agencies 

occur; was full 

implementation plan 

documentation provided to 

EPA, and was EPA’s stated 

concerns, if any, addressed?

Yes. Consultation has occurred 

among all required Federal, State,

and local agencies.

Sec. 93.118(e)(4)(iii) Were the MVEBs clearly

identified and precisely

quantified?

As there was a request for an 

insignificance finding, no MVEBs

were identified in the SIP. 

Sec. 93.118(e)(4)(iv) Are the motor vehicle 

emissions, when considered 

together with all other 

emission reductions, 

consistent with applicable 

EPA believes that motor vehicle 

emissions can be declared 

insignificant contributors because 

in comparing the motor vehicle

emissions to the overall emissions 
5

requirements for 

maintenance strategies?

inventory, the motor vehicle

emissions comprise only a small 

portion of the over PM2.5

emissions for the nonattainment 

area and are projected to continue 

to significantly decline due to fleet 

turnover.

Sec. 93.118(e)(4)(v) Are the motor vehicle 

emissions consistent with 

and clearly related to the 

emissions inventory and the 

control measures in the Plan?

EPA believes that the motor 

vehicle emissions have clearly

related to the emissions inventory

and control measures in the SIP 

submittal.

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

submitted maintenance plan: 

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 Sec. 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).

There are no revisions to the 

maintenance plan because this is 

the initial redesignation request, 

along with the associated 

maintenance plan for West 

Virginia Portion of the 

Parkersburg-Marietta, WV-OH

Area.

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

review public comments and 

the State’s responses to those 

comments with the submitted 

control strategy SIP?

There were no comments on the 

SIP related to the proposed 

insignificance finding request.

IV. Conclusion

Based upon our review and evaluation of the motor vehicle emissions contained in the West 

Virginia Redesignation Request and Maintenance Plan for the West Virginia Portion of the 

Parkersburg-Marietta, WV-OH 1997 PM2.5 Nonattainment Area, EPA finds that the SIP 

submittal meets the criteria in the transportation conformity rules for an insignificance finding for 

NOx, PM2.5, and SO2 contribution from motor vehicles. Weighing all the factors for an 
6

insignificance finding, particularly the minor contribution of mobile source PM2.5 and SO2, EPA 

has determined that the PM2.5 and SO2 contribution from motor vehicle emissions to the annual 

PM2.5 pollution for the West Virginia portion of the Nonattainment Area are insignificant. With 

respect to transportation conformity, the larger NOx contribution of less than twelve and a half 

percent of the area’s total NOx emissions in the 2015 and 2022 horizon years requires further 

justification to request an insignificant finding. The requirements under 40 CFR 93.109(f) bases 

insignificance on emission percentages, emission trends, and the effectiveness of the pollutant in 

forming PM. For the Parkersburg-Marietta area, there is a significant emission decrease 

projected for the highway sector and total emissions source inventory in years 2008, 2015, and 

2022. Given the relatively small contribution of the highway mobile emissions to the total SIP 

inventory, highway mobile emissions are not likely to contribute significantly to local PM2.5. 

Additionally, NOx reductions are significantly less effective in reducing PM concentrations than 

are reductions in direct PM and SO2. Consequently, NOx percentage emission contribution may

be higher than direct PM and SO2 without adversely affecting air quality. Based on the analysis 

of local historical trends and growth patterns in order to develop the long range transportation 

plan and transportation improvement program for transportation conformity purposes, EPA has

no reason to expect highway motor vehicle emissions growth to lead to a violation of the annual 

PM2.5 standard. Although vehicle miles traveled increases over time, NOx emissions are 

projected to decrease dramatically from 4505.4 tons/year in 2002 to 665.7 tons/year in 2030. 

This demonstrates that highway emissions will remain insignificant in the future. Upon review

of the further justification for requesting an insignificant finding for NOx, EPA has determined 

that NOx contribution from motor vehicle emissions to the annual PM2.5 pollution for the West 

Virginia portion of the Nonattainment Area is insignificant.