2024-18173. Air Plan Approval; Delaware; Motor Vehicle Inspection and Maintenance Program

Table 1—Low Enhanced Performance Standard Comparison for the Delaware portion of the Philadelphia-Wilmington-Atlantic City Ozone Nonattainment Area (Kent and New Castle Counties) ²⁹

I/M program element	EPA low enhanced performance standard	Delaware's low enhanced I/M program
Network Type	Centralized	Centralized.
Program Start Date	Existing programs—1983; Newly subject areas—1995	New Castle County—1995; Kent County—1991.
Test Frequency	Annual	Biennial.
Model Year Coverage	1968 and newer	1968 and newer (7 newest model years exempt).
Vehicle Type Coverage	Light-duty gasoline vehicles (LDGVs) and light-duty gasoline trucks (LDGTs), up to 8,500 lbs gross vehicle weight rating (GVWR)	1968 and newer LDGVs and LDGTs, up to 8,500 lbs GVWR; and 1970 and newer Medium Duty Gasoline Vehicles (MDVs), up to 14,000 lbs GVWR. 30
Exhaust Emission Test 31	Idle Test, (1968-1995 model years) 32	Curb Idle test (1968-1995 LDVs and LDTs; and 1970-1995).
Emission Standards	1981 and newer—1.2% CO. 1981 and newer—220 ppm HC	1981 and newer—1.2% CO. 1981 and newer—220 ppm HC.
Emission Control Device Visual Inspection33	1968-71 PCV valve; 1972 and newer EGR valve	1981 and newer Catalytic converter.
On-board Diagnostics II (OBDII) Inspection	1996 and newer LDGVs and LDGTs	1996 and newer LDGVs and LDGTs, up to 8,500 lbs GVWR; and 1997 and later LDDVs (light-duty diesel vehicles), up to 8,500 lbs GVWR; and 2008 and newer MDVs (gasoline or diesel), up to 14,000 lbs GVWR.34  35
( print page 66301)
Evaporative system function check	None	Gas Cap Pressure Test, for 1975-1995 vehicles.
Waiver Rate (for cost-limited I/M repair expenditures)	3%	3%.
Motorist Compliance Rate	96%	See Delaware SIP Appendix A of the Delaware Plan for Implementation for program compliance rate.
Evaluation Date 36  37	January 2002	January 2023.

Though Delaware is not required to demonstrate compliance with a performance standard in the Sussex County area, as I/M there was adopted as a SIP strengthening program (as described in section I. of this action), the State elected to demonstrate that the Sussex County program meets EPA's basic I/M performance standard in order to rely upon the benefits from this program to meet CAA noninterference requirements under section 110(l). Additionally, the Sussex County program provides additional reductions to offset impacts to the Wilmington area program from the changes to that program. Table 2, in this document, shows the I/M program parameters of the Sussex County program compared to those of EPA's basic I/M performance standard, to show the assumptions used to model the benefits of the Sussex County program and to demonstrate that the revised program does not backslide from that in the approved SIP.

Table 2—Basic I/M Performance Standard Comparison for Sussex County SIP Strengthening Program ³⁸

I/M program element	EPA basic performance standard	Delaware's SIP-strengthening I/M program
Network Type	Centralized	Centralized.
Program Start Date	Existing programs—1983; Newly subject areas—1994	Sussex County—1983.
Test Frequency	Annual	Biennial.
Model Year Coverage	1968 and newer	1968 and newer (7 newest model years exempt).
Vehicle Type Coverage	LDGVs	LDVs and LDTs (up to 8,500 lbs GVWR); MDVs, up to 14,000 lbs GVWR. 39
Exhaust Emission Test 40	Idle Test (1968-1995 model years) 41	Curb Idle test (1968-1995 model years).
Emission Standards	1981 and newer—1.2% CO; 1981 and newer—220 ppm HC	1981 and newer—1.2% CO; 1981 and newer—220 ppm HC.
Emission Control Device Visual Inspection 42	None	1981 and newer Catalytic converter.
On-board Diagnostics II (OBDII) Inspection	1996 and newer vehicles	1996 and newer LDGVs and LDGTs (up to 8,500 lbs GVWR); and 1997 and later LDDVs (light-duty diesel vehicles), up to 8,500 lbs GVWR; and 2008 and newer MDVs (gasoline or diesel), up to 14,000 lbs GVWR.  43 44
Evaporative system function check	None	Gas Cap Pressure Test, for 1975-1995 vehicles.
Waiver Rate (for repair expenditure limits for I/M repairs)	0%	3%.
Motorist Compliance Rate	100%	See Appendix A of the Delaware SIP Plan for Implementation for compliance rate.
Evaluation Date 45  46	January 2002	January 2023.

To demonstrate the applicable performance standard has been met, the state must model the emissions benefits of its program against that of EPA's model program, comparing the results to show that their program is at least as beneficial as the applicable performance standard. For an area subject to I/M under the ozone NAAQS, this analysis (performed using the latest available version of EPA's Motor Vehicle Emissions Simulator Model (MOVES) ( print page 66302) entails the comparison of the resultant levels, expressed as a comparison of average grams per mile (gpm), of the ozone precursors nitrogen oxides (NO_X ) and volatile organic compounds (VOCs), from highway mobile sources in the I/M area, as derived from MOVES. For purposes of this comparison, the state uses the latest available meteorological and vehicle composition and usage data, keeping constant all other mobile source emission control program assumptions between the model program and state program scenarios.^[47] For comparison purposes, Delaware also modeled a hypothetical “no I/M” scenario to show the emissions for the same area with no benefits from an I/M program. Delaware used MOVES2014b as the emissions model to generate 2023 evaluation year emissions scenarios. Though EPA has since released newer versions of the MOVES model ( i.e., MOVES3 and MOVES4), Delaware commenced development of their MOVES SIP analyses prior to the release of MOVES 3 in 2020.^[48]

Table 3, in this document, shows the results of Delaware's low enhanced I/M performance standard analysis for the Delaware portion of the Philadelphia-Wilmington-Atlantic City area. As the modeling depicted in Table 3 demonstrates, the NO_X and VOC emission levels meet EPA's relevant I/M performance standard, as MOVES modeling for both Kent and New Castle Counties demonstrate that both county's programs are within the regulatory allowance (40 CFR 51.351(g)(13)) of 0.02 gpm as compared to emission levels resulting from EPA's Low Enhanced Performance Standard of 40 CFR 51.351.

Table 3—Low Enhanced Performance Standard Modeling Results for the Delaware Portion of the Philadelphia-Wilmington-Atlantic City I/M Program for a 2023 Evaluation Year (Kent and New Castle Counties) ⁴⁹

County	I/M program design	NO X (in grams per mile)	VOC (in grams per mile)
Kent	No I/M Program	0.5139	0.3171
	Low Enhanced Performance Standard	0.4871	0.2869
	Delaware 2023 Program	0.4794	0.2831
	Performance Standard Margin	0.0077	0.0038
New Castle	No I/M Program	0.4236	0.2557
	Low Enhanced Performance Standard	0.3988	0.2289
	Delaware 2023 Program	0.3950	0.2300
	Performance Standard Margin	0.0038	50  −0.0011

As described in the Background section of this action, an I/M program is not CAA-required in Sussex County, Delaware—as the Seaford area meets neither the minimum MSA population threshold specified under CAA section 184, nor the minimum urbanized area population threshold for a nonattainment area under CAA section 182. However, Delaware elected to voluntarily implement an I/M program in Sussex County as a SIP strengthening measure and to provide additional ozone precursor emission reductions to benefit the Delaware portion of the Philadelphia-Wilmington-Atlantic City ozone nonattainment area. In order to quantify the benefits of this program, for the purpose of claiming benefits from the program to contribute to attainment of the Philadelphia-Wilmington-Atlantic City nonattainment area, Delaware elected to institute a program design similar to EPA's basic I/M performance standard.^[51] EPA's review of Delaware's updates to the Sussex County SIP-strengthening program finds that the revised program is substantially similar to CAA requirements for a basic I/M program.

2. Demonstrating Noninterference of the Revised SIP Under CAA Section 110(l) With Attainment, Reasonable Further Progress, or Any Other CAA Applicable Requirement

In the case where a state elects to revise its SIP-approved I/M program, in addition to meeting the applicable CAA section 182 program requirements and applicable performance standard compliance, the state must also demonstrate that the revisions to the prior, SIP-approved I/M program will not interfere with the area's ability to attain or maintain any NAAQS, or with any other applicable CAA requirement. This type of demonstration is known as a CAA section 110(l) noninterference demonstration.

In order to offset any potential increase in emissions due to expansion of new car I/M exemptions to seven model years (as a result of a State law change (HB 246)), DNREC elected to harmonize inspection requirements more closely between the low enhanced Regulation 1131 program in the Wilmington area and the Regulation 1126 SIP strengthening I/M program in Sussex County. This includes: (1) the addition of OBD II checks to Sussex County; (2) expansion of OBD testing in all counties, to include OBD II testing for model year 2008 and newer medium duty vehicles between 8500-14,000 lbs GVWR; (3) elimination of 2-speed idle tailpipe testing in the Wilmington area, while retaining curb idle tailpipe testing for pre-1996 LDGVs in all areas (including Sussex County); (4) extension of gas cap pressure check testing to pre-1996 I/M-subject vehicles; and (5) retention of visual inspection for catalytic converters in all counties.

See Table 4, in this document, for a comparison in the difference between emissions under the March 2023 SIP ( print page 66303) revision I/M programs and the prior SIP-approved Delaware I/M program.

Table 4—CAA 110( l ) Noninterference Demonstration—Difference Between Delaware's Baseline (Prior, Approved SIP Program) and the 2023 Revised I/M Program (All Program Areas) ⁵²

County	Program description	Difference from baseline SIP in carbon monoxide (CO) (tons per year)	Difference from baseline SIP in VOC (tons per year)	Difference from baseline SIP in NO X (tons per year)
Kent	Baseline SIP Program
	2023 Revised I/M Program	+17.1	+0.3	+0.7
New Castle	Baseline SIP Program
	2023 Revised I/M Program	+184.0	+10.1	+7.8
Sussex	Baseline SIP Program
	2023 Revised I/M Program	−594.2	−112.0	−54.1
Net Change (Statewide)	2023 Revised I/M Program	−393.1	−101.6	−45.6