2024-22114. Air Plan Approval; Connecticut; New Haven and Fairfield Counties Second 10-Year Limited Maintenance Plan for the 2006 24-Hour PM2.5 Standard

Table 2—PM _2.5 Design Values in New Haven-Fairfield Since Redesignation to Attainment in µg/m³

[2013-2023]

Design value period	090010010— Roosevelt School— Bridgeport	090011123— Western Conn State University	090090027— Criscuolo Park— New Haven	090092123— Meadow and Bank Streets
2011-2013	23	25	24	23
2012-2014	23	24	21	24
2013-2015	24	25	22	24
2014-2016	24	23	20	* 23
2015-2017	21	22	20	* 20
2016-2018	20	21	19	* 20
2017-2019	19	20	18	19
2018-2020	21	21	20	20
2019-2021	22	21	21	20
2020-2022	21	22	21	21
2021-2023	21	21	20	6  20
* 24-hr data invalid due to site reconstruction.

EPA proposes to find that the New Haven-Fairfield area meets the critical design value demonstration for an LMP. As noted above, the parameters of the CDV calculation include the level of the relevant NAAQS, the co-efficient of variation of recent design values, and a statistical parameter corresponding to a 10 percent probability of future violation. The CDV demonstration is designed such that if a site's ADV is lower than the site's CDV, the probability of a future violation of the NAAQS is less than 10 percent.^[7] Section 2.2 of CT DEEP's LMP submittal demonstrates the likelihood of continued attainment. EPA reviewed the data and methodology provided by the state and we find that each monitor's 5-year ADV is well below the corresponding site-specific CDV, as shown in table 3.

Table 3—Results of Calculation of CDVs at New Haven-Fairfield Monitors for the 24-Hour PM _2.5 NAAQS

Site	CDV	Average design value (2017-2021) a	Qualify for LMP?
090010010	32.3	20.6	Yes.
090011123	33.3	21.0	Yes.
090090027	32.1	19.6	Yes.
090092123	33.2	b  19.7	Yes.
a  CT DEEP uses the term `mean' interchangeably with ADV in the proposed LMP; the design values averaged for the ADV span seven years of data (2015-2017, 2016-2018, 2017-2019, 2018-2020, 2019-2021).
b  Only three years of design values (5 years of data) were used for the Meadow and Bank Streets' monitor due to site reconstruction. activities resulting in incomplete data for 2016 and invalidating design values for 2016-2018.

We also propose to find that the CT DEEP LMP submittal satisfies transportation conformity regulations under the LMP option. Connecticut holds annual transportation conformity interagency consultation meetings which include Federal, State, and local agencies. Additionally, the LMP SIP submittal for New Haven-Fairfield was developed in accordance with interagency consultation between Federal, State, and local partners. CT DEEP also includes analysis that addresses the demonstration under 40 CFR 93.109(e) in their supplement submitted on February 21, 2024. This transportation conformity regulation requires that an LMP would have to demonstrate that it would be unreasonable to expect that a maintenance area would experience enough motor vehicle emissions growth for a NAAQS violation to occur (40 CFR 93.109(e)).

The state's demonstration assesses the total projected growth in on-road motor vehicle PM_2.5 emissions through the end of the 20-year maintenance period, where the projected percentage increase in vehicle miles traveled (VMT_pi) to the end of the 20-year maintenance period ( i.e., 2033), is multiplied by the motor vehicle design value (DV_mv). The DV_mv is based on the on-road mobile portion of the attainment year inventory. CT DEEP analyzed whether the area's ADV for the period used to demonstrate LMP qualification plus (VMT_pi × DV_mv) was less than or equal to the CDV for the relevant PM_2.5 standard in µg/m^[3] for the given area. The state calculated the CDV for the entire maintenance area, 33 μg/m^[3] , using the most recent (2017-2021) maximum design values from each year.^[8] CT DEEP calculated the projected ( print page 79193) design value in 2033 to be 21.49 μg/m³ which is less than the determined CDV, 33 μg/m³ . Thus, CT DEEP concludes that it is unlikely that increased emissions from on-road mobile sources could, in the next 10 years, increase concentrations in the area enough to threaten the maintenance of the PM_2.5 NAAQS. In consultation with the Connecticut Department of Transportation (CTDOT), CT DEEP also provided a VMT_pi of .0565 from 2017 to 2033, which is a 5.65% increase.

The VMT projection considered by Connecticut was based on the on-road emissions analysis calculation as laid out in the PM₁₀ LMP Guidance. Under the PM_2.5 LMP Guidance, this on-road emissions analysis is only necessary for LMPs where re-entrained road dust has been found to be significant for PM_2.5 transportation conformity purposes under 40 CFR 93.102(b)(3) for a given maintenance area. While CT DEEP does not identify re-entrained road dust as a significant contributor to PM_2.5 concentrations in the maintenance area, the state utilizes the same methodology to address projected VMT and motor vehicle emissions growth in its LMP submittal. CT DEEP's analysis indicates that the projected design value in 2033 is significantly below the area's CDV signaling future continued maintenance of the relevant NAAQS, with limited growth in VMT from 2017 to 2033. This analysis supports a conclusion that the state has demonstrated that it would be unreasonable to expect New Haven-Fairfield to experience enough growth in on-road emissions during the remaining maintenance period such that a violation of the 2006 24-hour PM_2.5 NAAQS will occur.

Also, per 40 CFR 93.109(e), an area with an adequate or approved LMP is not required to satisfy the regional emissions analysis for § 93.118 and/or § 93.119 for a given pollutant and NAAQS, in this instance the 2006 PM_2.5 NAAQS. However, the first 10-year maintenance plan for the New Haven-Fairfield area included motor vehicle emissions budgets for 2025. Therefore, if 2025 is within the timeframe of any transportation plan or transportation improvement program (TIP) and transportation conformity is determined for that plan or TIP, a regional emissions analysis is required for 2025.

In the PM_2.5 LMP Guidance, EPA clarifies that an area submitting the second 10-year maintenance plan may be eligible for the LMP option if monitored air quality data and VMT trends support the LMP option. Given the air quality data demonstrating that New Haven- Fairfield has been maintaining the 2006 PM_2.5 NAAQS for at least 8 years, the current PM_2.5 design values in the area, the demonstrated downward trend in PM_2.5 concentrations over the last ten years, and the state's on-road emissions analysis of projected VMT discussed above, we propose to find that CT DEEP's LMP submittal for the New Haven-Fairfield 2006 PM_2.5 maintenance area meets the qualification criteria for an LMP, consistent with 40 CFR 93.109(e) and the PM_2.5 LMP Guidance.

The following is a summary of EPA's interpretation of the section 175A requirements and EPA's evaluation of how each requirement is met. Under the LMP option, the state will be expected to determine on a regular basis that the criteria are still being met. If the state determines that the LMP criteria are not being met, it should take action to reduce PM_2.5 concentrations enough to requalify. One possible approach the state could take is to implement the contingency measures contained in its first maintenance plan (78 FR 58467), that the state will continue to adhere to for the second maintenance period ( See section 3.6 of the current state submittal). If the attempt to reduce PM_2.5 concentrations fails, or if it succeeds but in future years it becomes necessary again to address increasing PM_2.5 concentrations in an area, the area will no longer qualify for the LMP option.

B. Attainment Inventory

As noted above, states that qualify for an LMP must still meet the other elements of a maintenance plan, as articulated in the Calcagni Memo. This includes an attainment year emissions inventory. CT DEEP's New Haven-Fairfield PM_2.5 LMP submission includes an emissions inventory, with a base year of 2017. This inventory was prepared as part of the 2017 National Emissions Inventory ^[9] Version 2 under EPA's Air Emissions Reporting Rule (73 FR 76539, December 17, 2008). The 2017 base year represents the most recent emissions inventory data available when the state prepared the submission and is representative of the level of emissions during a period that the area shows monitored attainment of the NAAQS and is consistent with the data used to determine applicability of the LMP option ( i.e., having no violations of the NAAQS during the 5-year period used to calculate the design value). Table 3 shows the total 2017 emissions in New Haven-Fairfield in tons per year included in the state's submission.

Table 3—2017 Emissions (Tons/Year) in New Haven-Fairfield

Pollutant	Total emissions
PM 2.5	4,361
Ammonia (NH 3 )	1,485
Nitrogen oxides (NO X )	22,020
Sulfur dioxide (SO 2 )	1,296
Volatile organic compounds (VOCs)	43,518