Federal Register / Vol. 89, No. 188 / Friday, September 27, 2024 / Proposed Rules 79189 

Dated: September 23, 2024. 

David Cash, 

Regional Administrator, EPA Region 1. 

[FR Doc. 2024–22115 Filed 9–26–24; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R01–OAR–2024–0117; FRL–12283– 

01–R1] 

Air Plan Approval; Connecticut; New 

Haven and Fairfield Counties Second 

10-Year Limited Maintenance Plan for 

the 2006 24-Hour PM2.5 Standard 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: The Environmental Protection 

Agency (EPA) is proposing to approve, 

under the Clean Air Act (CAA), the 

limited maintenance plan (LMP) for the 

2006 PM2.5 national ambient air quality 

standard (NAAQS) for New Haven and 

Fairfield Counties, which comprise the 

Connecticut portion of the New York-N. 

New Jersey-Long Island (NY-NJ-CT) 

2006 PM2.5 NAAQS maintenance area. 

This LMP was submitted on May 9, 

2023, and supplemented on February 

21, 2024, by the Connecticut 

Department of Energy and 

Environmental Protection (CT DEEP). 

The plan addresses the second 10-year 

maintenance period for particulate 

matter with an aerodynamic diameter 

less than or equal to a nominal 2.5 

micrometers, known as PM2.5. EPA is 

proposing approval of Connecticut’s 

LMP submission because it provides for 

the maintenance of the 2006 24-hour 

PM2.5 NAAQS through the end of the 

second 10-year portion of the 

maintenance period. In addition, EPA is 

initiating the process to find the 

Connecticut PM2.5 LMP adequate for 

transportation conformity purposes. 

DATES: Written comments must be 

received on or before October 28, 2024. 

ADDRESSES: Submit your comments, 

identified by Docket ID No. EPA–R01– 

OAR–2024–0117 at https://

www.regulations.gov, or via email to 

martinelli.ayla@gmail.com. For 

comments submitted at Regulations.gov, 

follow the online instructions for 

submitting comments. Once submitted, 

comments cannot be edited or removed 

from Regulations.gov. For either manner 

of submission, the EPA may publish any 

comment received to its public docket. 

Do not submit electronically any 

information you consider to be 

Confidential Business Information (CBI) 

or other information whose disclosure is 

restricted by statute. Multimedia 

submissions (audio, video, etc.) must be 

accompanied by a written comment. 

The written comment is considered the 

official comment and should include 

discussion of all points you wish to 

make. The EPA will generally not 

consider comments or comment 

contents located outside of the primary 

submission (i.e., on the web, cloud, or 

other file sharing system). For 

additional submission methods, please 

contact the person identified in the FOR

FURTHER INFORMATION CONTACT section. 

For the full EPA public comment policy, 

information about CBI or multimedia 

submissions, and general guidance on 

making effective comments, please visit 

https://www.epa.gov/dockets/ 

commenting-epa-dockets. Publicly 

available docket materials are available 

at https://www.regulations.gov or at the 

U.S. Environmental Protection Agency, 

EPA Region 1 Regional Office, Air and 

Radiation Division, 5 Post Office 

Square—Suite 100, Boston, MA. EPA 

requests that, if possible, you contact 

the contact listed in the FOR FURTHER

INFORMATION CONTACT section to 

schedule your inspection. The Regional 

Office’s official hours of business are 

Monday through Friday, 8:30 a.m. to 

4:30 p.m., excluding legal holidays and 

facility closures due to COVID–19. 

FOR FURTHER INFORMATION CONTACT: Ayla 

Martinelli, Air Quality Branch, U.S. 

Environmental Protection Agency, EPA 

Region 1, 5 Post Office Square—Suite 

100, (Mail code 5–MI), Boston, MA 

02109–3912, tel. (617) 918–1057, email 

martinelli.ayla@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Throughout this document whenever 

‘‘we,’’ ‘‘us,’’ or ‘‘our’’ is used, we mean 

EPA. 

Table of Contents 

I. Background and Purpose 

A. The PM2.5 National Ambient Air Quality 

Standards (NAAQS) 

B. Regulatory Actions in New Haven and 

Fairfield Counties 

II. The Limited Maintenance Plan Option 

A. Demonstration of Maintenance Using 

the Limited Maintenance Plan Option 

B. Transportation Conformity Under 

Limited Maintenance Plan Option 

C. General Conformity Under Limited 

Maintenance Plan Option 

III. EPA’s Analysis of the State’s Submittal 

A. Demonstration of Qualification for the 

Limited Maintenance Plan Option 

B. Attainment Inventory 

C. Air Quality Monitoring Network 

D. Verification of Continued Attainment 

E. Contingency Provisions 

IV. Proposed Action 

V. Statutory and Executive Order Reviews 

I. Background and Purpose 

A. The PM2.5 National Ambient Air 

Quality Standards (NAAQS) 

EPA has established NAAQS for 

particulate matter with an aerodynamic 

diameter less than or equal to 2.5 

micrometers, known as PM2.5, to protect 

human health and the environment. In 

1997, EPA established the first PM2.5

standards based on significant scientific 

evidence and health studies 

demonstrating the serious health effects 

associated with exposure to PM2.5. EPA 

set an annual standard of 15.0 

micrograms per cubic meter (mg/m3) and 

a 24-hour (or daily) standard of 65 mg/ 

m3. In 2006, EPA strengthened the 24- 

hour PM2.5 NAAQS by revising it to 

35 mg/m3 and retained the level of the 

annual PM2.5 standard at 15.0 mg/m3. 

Subsequently, in 2012, EPA established 

an annual primary PM2.5 NAAQS at 

12.0 mg/m3 and retained the 2006 24- 

hour PM2.5 NAAQS at 35 mg/m3. In early 

2024, EPA strengthened the level of the 

annual primary PM2.5 standard to 9.0 mg/ 

m3 and retained the 2006 24-hour PM2.5

NAAQS at 35 mg/m3. 

B. Regulatory Actions in New Haven 

and Fairfield Counties 

Hereafter, ‘‘New Haven-Fairfield’’ 

means the Connecticut portion of the 

NY-NJ-CT maintenance area which is 

comprised of New Haven and Fairfield 

Counties. EPA promulgated the 

designations for New Haven-Fairfield as 

a PM2.5 nonattainment area for the 1997 

annual PM2.5 NAAQS on January 5, 

2005 (70 FR 944) and the 2006 24-hour 

PM2.5 NAAQS (74 FR 58688) on 

November 13, 2009, due to measured 

violations of the standards. These 

designations became effective on April 

5, 2005, and December 14, 2009, 

respectively. On June 22, 2012, CT 

DEEP submitted a request to EPA to 

redesignate the New Haven- Fairfield 

nonattainment area to attainment of 

both the 1997 annual and 2006 24-hour 

PM2.5 NAAQS. This submittal included 

a maintenance plan to provide for 

maintenance of the PM2.5 NAAQS in the 

area for 10 years. EPA redesignated New 

Haven-Fairfield to attainment for the 

1997 and 2006 PM2.5 NAAQS on 

October 24, 2013 (78 FR 58467) and 

approved the associated maintenance 

plan into the Connecticut State 

Implementation Plan (SIP). The purpose 

of CT DEEP’s May 9, 2023 

(supplemented on February 21, 2024) 

LMP submission is to fulfill the second 

10-year planning requirement of CAA 

section 175A(b), thus ensuring PM2.5

NAAQS compliance through the end of 

the maintenance period. 


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79190 Federal Register / Vol. 89, No. 188 / Friday, September 27, 2024 / Proposed Rules 

1See Calcagni, John, Director, Air Quality 

Management Division, EPA Office of Air Quality 

Planning and Standards, ‘‘Procedures for Processing 

Requests to Redesignate Areas to Attainment,’’ 

September 4, 1992 (Calcagni memo). A copy of this 

memorandum can be found in the docket for this 

proposed rulemaking. 

2See ‘‘Limited Maintenance Plan Option for 

Nonclassifiable Ozone Nonattainment Areas’’ from 

Sally L. Shaver, Office of Air Quality Planning and 

Standards (OAQPS), dated November 16, 1994; 

‘‘Limited Maintenance Plan Option for 

Nonclassifiable CO Nonattainment Areas’’ from 

Joseph Paisie, OAQPS, dated October 6, 1995; and 

‘‘Limited Maintenance Plan Option for Moderate 

PM10 Nonattainment Areas’’ (PM10 LMP Guidance) 

from Lydia Wegman, OAQPS, dated August 9, 2001. 

Copies of these guidance memoranda can be found 

in the docket for this proposed rulemaking. 

3See the guidance document developed by the 

Office of Air Quality Planning and Standards, the 

Office of Transportation and Air Quality, and the 

Office of Air and Radiation titled ‘‘Guidance on the 

Limited Maintenance Plan Option for Moderate 

PM2.5 Nonattainment Areas and PM2.5 Maintenance 

Areas’’. A copy of this guidance can be found in the 

docket for this proposed rulemaking. 

4EPA recommends that the ADV be calculated 

using at least five years of design values, each 

representing a three-year period, because this 

approach would rely on a more robust dataset. 

However, we acknowledge that an alternative 

interpretation may be acceptable, where these 

variables could be calculated using three years of 

design values, collectively representing five years of 

air quality data. 

In the LMP submittal, CT DEEP 

indicates that it is seeking approval of 

the LMP for both the 2006 24-hour 

standard as well as the 1997 annual 

standard. However, as explained in the 

PM2.5 SIP Requirements Rule (81 FR 

58009), a second 10-year maintenance 

plan for the revoked 1997 annual PM2.5

NAAQS is not required. Therefore, CT 

DEEP clarified via email that it 

incorrectly sought approval of the plan 

for the revoked 1997 annual standard 

and asked that EPA ignore the request 

for approval of the plan for this 

standard. The email, sent on July 7, 

2023, can be found in the docket of this 

action. Thus, EPA will only proceed 

with proposing approval of the LMP for 

the 2006 24-hour PM2.5 NAAQS. 

II. The Limited Maintenance Plan 

Option 

A. Demonstration of Maintenance Using 

the Limited Maintenance Plan Option 

Section 175A of the CAA sets forth 

the elements of a maintenance plan. 

Under section 175A, a state must submit 

a revision to the SIP that provides for 

maintenance of the applicable NAAQS 

for at least 10 years after an area is 

redesignated to attainment. Section 

175A also requires that eight years into 

the first maintenance period, the state 

must submit a second maintenance plan 

demonstrating that the area will 

continue to attain for the following 10- 

year period. 

EPA has published long-standing 

guidance for states on developing 

maintenance plans.1 The Calcagni 

memo provides that states may 

generally demonstrate maintenance by 

either performing air quality modeling 

to show that the future mix of sources 

and emission rates will not cause a 

violation of the NAAQS or by showing 

that future emissions of a pollutant and 

its precursors will not exceed the level 

of emissions during a year when the 

area was attaining the NAAQS (i.e., 

attainment year inventory). EPA 

clarified in subsequent guidance memos 

that certain nonattainment areas could 

meet the CAA section 175A requirement 

to provide for maintenance by 

demonstrating that an area’s design 

value is well below the NAAQS and that 

the historical stability of the area’s air 

quality levels shows that the area is 

unlikely to violate the NAAQS in the 

future.2

Most recently, in October 2022, EPA 

released guidance extending this 

streamlined option for demonstrating 

maintenance under CAA section 175A 

to certain PM2.5 areas, titled ‘‘Guidance 

on Limited Maintenance Plan Option for 

Moderate PM2.5 Nonattainment Areas 

and PM2.5 Maintenance Areas’’ (PM2.5

LMP Guidance).3 EPA refers to this 

streamlined demonstration of 

maintenance as an LMP. EPA has 

interpreted CAA section 175A as 

permitting this option because section 

175A of the Act defines few specific 

content requirements for maintenance 

plans, and in EPA’s experience 

implementing the various NAAQS, 

areas that qualify for an LMP and have 

approved LMPs have rarely, if ever, 

experienced subsequent violations of 

the NAAQS. As noted in the PM2.5 LMP 

Guidance, states seeking an LMP should 

still submit the other maintenance plan 

elements outlined in the Calcagni 

memo, including: an attainment 

emissions inventory, provisions for the 

continued operation of the ambient air 

quality monitoring network, verification 

of continued attainment, and a 

contingency plan in the event of a future 

violation of the NAAQS. Moreover, 

states seeking an LMP must still submit 

their section 175A maintenance plan as 

a revision to their SIP, with all attendant 

notice and comment procedures. 

The PM2.5 LMP Guidance, similar to 

the PM10 LMP Guidance, allows states 

to demonstrate that certain areas qualify 

for an LMP by showing that, based on 

their recent measured air quality, they 

are unlikely to violate the NAAQS in 

the future. Specifically, the PM2.5 LMP 

Guidance relies on the critical design 

value (CDV) concept. This guidance 

directs states to calculate a site-specific 

CDV for the monitoring site in an area 

with the highest design value, and also 

for all other active monitoring sites in 

the area with complete data. The PM2.5

LMP Guidance states that areas should 

show that the average design value 

(ADV) for each monitoring site in the 

area, i.e., the average of at least the most 

recent consecutive 5 years of PM2.5

design values, does not exceed the 

associated CDV for each site.4 If the 

ADV for each monitoring site in the area 

is below the CDV then the probability of 

a future exceedance, based on the area’s 

historical air quality and variability, is 

less than 10 percent. The CDV 

calculation for a monitoring site 

involves the following parameters: (1) 

the level of the relevant NAAQS; (2) the 

co-efficient of variation of recent design 

values measured at that site; and (3) a 

statistical parameter corresponding to a 

10 percent probability of exceedance, 

such that sites with historically high 

variability in design values result in a 

lower (or more stringent) CDV. The 

eligibility calculation equations for the 

CDV demonstration are shown in table 

1. 


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5See https://www.epa.gov/air-trends/air-qualitydesign-values. 

B. Transportation Conformity Under 

Limited Maintenance Plan Option 

Transportation conformity is required 

by section 176(c) of the CAA. Under that 

provision, conformity to a SIP means 

that transportation activities will not 

cause or contribute to new air quality 

violations, worsen existing violations, 

delay timely attainment of the NAAQS 

or any required interim emission 

reductions or other milestones in any 

area. See CAA 176(c)(1)(A) and (B). 

EPA’s transportation conformity rule at 

40 CFR part 93 subpart A establishes the 

criteria and procedures to determine 

whether metropolitan transportation 

plans, transportation improvement 

programs, and federally supported 

highway and transit projects conform to 

the SIP. Transportation conformity 

applies for transportation-related 

criteria pollutants in nonattainment 

areas and redesignated attainment areas 

with a CAA section 175A maintenance 

plan (i.e., maintenance areas). 

While qualification for the LMP 

option does not exempt an area from the 

need to determine conformity, in an 

area with an adequate or approved LMP, 

conformity may be demonstrated for a 

transportation plan or a transportation 

improvement program without a 

regional emissions analysis for the 

relevant NAAQS and pollutant (40 CFR 

93.109(e)). However, transportation plan 

and transportation improvement 

program conformity determinations that 

meet applicable requirements continue 

to be required in these areas (see table 

1 in 40 CFR 93.109). The areas also 

remain subject to the other 

transportation conformity requirements 

of 40 CFR part 93, subpart A, including 

fulfilling project-level conformity 

analyses requirements and consultation 

requirements. In addition, an LMP must 

demonstrate that it is unreasonable to 

expect that the qualifying area would 

experience enough growth in on-road 

emissions during the maintenance 

period such that a violation of the 

relevant NAAQS would occur (40 CFR 

93.109(e)). Furthermore, consistent with 

the PM2.5 LMP Guidance, if re-entrained 

road dust has been found to be 

significant for PM2.5 transportation 

conformity purposes under 40 CFR 

93.102(b)(3), the plan should include an 

on-road PM2.5 emissions analysis 

consistent with the methodology 

provided in attachment B of the PM10

LMP Guidance. EPA discusses CT 

DEEP’s submittal in section III.A of this 

notice. 

Along with this proposed action, EPA 

is initiating an adequacy process for the 

New Haven and Fairfield LMP. See 40 

CFR 93.118(e)(4) and 93.118(f). Since 

LMPs do not include motor vehicle 

emissions budgets, EPA’s adequacy 

review is to assess whether the 

demonstration required by 40 CFR 

93.109(e) is met. 

C. General Conformity Under Limited 

Maintenance Plan Option 

The general conformity rule of 

November 30, 1993 (58 FR 63214) 

applies to nonattainment areas and 

redesignated attainment areas operating 

under maintenance plans (i.e., 

maintenance areas). General conformity 

requires compliance to the purpose of a 

SIP, which means that federal activities 

not related to transportation plans, 

programs, and projects will not cause or 

contribute to any new violation of any 

standard in any area, increase the 

frequency or severity of any existing 

violation of any standard in any area or 

delay timely attainment of any standard 

or any required interim emission 

reductions or other milestones in any 

area (CAA section 

176(c)(1)(A)and(1)(B)). As noted in the 

PM2.5 LMP Guidance, EPA’s general 

conformity regulations do not 

distinguish between maintenance areas 

with an approved ‘‘full maintenance 

plan’’ and those with an approved LMP. 

Thus, maintenance areas with an 

approved LMP are subject to the same 

general conformity requirements under 

40 CFR part 93 subpart B, as those 

covered by a ‘‘full maintenance plan.’’ 

Full compliance with the general 

conformity program is required within 

an LMP. 

III. EPA’s Analysis of the State’s 

Submittal 

A. Demonstration of Qualification for 

the Limited Maintenance Plan Option 

EPA redesignated New HavenFairfield to attainment of the PM2.5

NAAQS on October 24, 2013 (78 FR 

58467). Table 2 below shows the 

historical design values for each 

monitoring site within the maintenance 

area since it was redesignated in 2013.5

The 2006 24-hour PM2.5 NAAQS is 

attained when the 3-year average of the 

98th percentile of 24-hour PM2.5


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Table 1. The Critical Desit?n Value Calculation 

Standard Deviation ( a) 

Coefficient of Variation (CV) 

Critical Design Value (CDV) 

ADV= Average of 3-year design values. 

DV = Design value. 

NAAQS = Applicable standard (35 μglm3). 

I 2 L (Xi -ADV) 

c;= 

'\J n-1 

CV=a/ADV 

CDV = NAAQS/(1 +(tc * CV)) 

tc = Critical t-value (based on the one-tail student's t-distribution, at a significance level of0.10). 

x; = a given three-year period design value for the area. 

n = the total number of design values evaluated, which in this case is f,ve. 
79192 Federal Register / Vol. 89, No. 188 / Friday, September 27, 2024 / Proposed Rules 

6The 2020–2022 and 2021–2023 design values 

were not finalized until after CT DEEP submitted 

the PM2.5 LMP to EPA; they are included here to 

show the most recent air quality data. 

7See the ‘‘Example Site Calculation’’, page 7 of 

the October 2022 PM2.5 LMP guidance, found in the 

docket for this rulemaking. 

8See appendix A of the state submittal for the 

complete calculation, which is included in the 

docket of this rulemaking. 

concentrations is equal to or less than 

35 mg/m3, and as shown in table 2, the 

area has been measuring air quality well 

below the 2006 PM2.5 NAAQS with an 

overall decrease in PM2.5 concentrations 

over time. These design values from the 

individual monitoring sites within the 

maintenance area demonstrate the 

stability of ambient PM2.5

concentrations over time. 

TABLE 2—PM2.5 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 PM2.5 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). bOnly 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 PM2.5 emissions through the end 

of the 20-year maintenance period, 

where the projected percentage increase 

in vehicle miles traveled (VMTpi) to the 

end of the 20-year maintenance period 

(i.e., 2033), is multiplied by the motor 

vehicle design value (DVmv). The DVmv

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 (VMTpi × DVmv) was 

less than or equal to the CDV for the 

relevant PM2.5 standard in mg/m3 for the 

given area. The state calculated the CDV 

for the entire maintenance area, 33 mg/ 

m3, using the most recent (2017–2021) 

maximum design values from each 

year.8 CT DEEP calculated the projected 


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9See https://www.epa.gov/air-emissionsinventories/2017-national-emissions-inventory-neidata. 

10See CT DEEP’s 2023 Annual Air Monitoring 

Network Plan found in the docket for this proposed 

rulemaking. 

11See EPA’S Approval Letter for CT DEEP’S 2023 

Annual Monitoring Network Plan found in the 

docket for this proposed rulemaking. 

design value in 2033 to be 21.49 mg/m3

which is less than the determined CDV, 

33 mg/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 PM2.5

NAAQS. In consultation with the 

Connecticut Department of 

Transportation (CTDOT), CT DEEP also 

provided a VMTpi 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 PM2.5 LMP Guidance, this on-road 

emissions analysis is only necessary for 

LMPs where re-entrained road dust has 

been found to be significant for PM2.5

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 PM2.5

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 HavenFairfield to experience enough growth 

in on-road emissions during the 

remaining maintenance period such that 

a violation of the 2006 24-hour PM2.5

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 PM2.5

NAAQS. However, the first 10-year 

maintenance plan for the New HavenFairfield 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 PM2.5 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 PM2.5 NAAQS for 

at least 8 years, the current PM2.5 design 

values in the area, the demonstrated 

downward trend in PM2.5

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 PM2.5

maintenance area meets the 

qualification criteria for an LMP, 

consistent with 40 CFR 93.109(e) and 

the PM2.5 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 PM2.5 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 

PM2.5 concentrations fails, or if it 

succeeds but in future years it becomes 

necessary again to address increasing 

PM2.5 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 HavenFairfield PM2.5 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 

PM2.5 .................................... 4,361 

Ammonia (NH3) .................... 1,485 

Nitrogen oxides (NOX) .......... 22,020 

Sulfur dioxide (SO2) ............. 1,296 

Volatile organic compounds 

(VOCs) .............................. 43,518 

C. Air Quality Monitoring Network 

Once an area is redesignated, the state 

must continue to operate an appropriate 

air monitoring network in accordance 

with 40 CFR part 58 to verify the 

attainment status of the area. CT DEEP 

continues to operate a PM2.5 monitoring 

network sited and maintained in 

accordance with federal siting and 

design criteria in 40 CFR part 58, and in 

consultation with EPA Region 1. CT 

DEEP submitted its 2023 Annual 

Monitoring Network Plan on June 26, 

2023,10 which EPA approved on July 12, 

2023.11 In the LMP submittal, CT DEEP 

commits to continued operation of its 

PM2.5 monitors within New HavenFairfield, consistent with the EPAapproved CT DEEP annual network 

plan. Currently, there are 4 monitors in 

the New Haven-Fairfield maintenance 

area. 

D. Verification of Continued Attainment 

The level of the 2006 24-hour PM2.5

NAAQS is 35 mg/m3 (40 CFR 50.13). The 

NAAQS is attained when the 3-year 

average of the 98th percentile of PM2.5

concentrations is equal to or less than 

the NAAQS, which CT DEEP has proven 

in its LMP submittal. As stated 

previously, CT DEEP commits to 

verifying continued attainment of the 

PM2.5 standards through the 

maintenance plan period with the 

operation of an appropriate PM2.5

monitoring network. In developing the 

second 10-year maintenance plan, CT 

DEEP evaluated the last 5 years of 

complete, quality-assured data (2017 

through 2021) for New Haven-Fairfield 

at the time of the submittal to verify 

continued attainment of the standard. 

Certified air quality data from 2023, as 


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79194 Federal Register / Vol. 89, No. 188 / Friday, September 27, 2024 / Proposed Rules 

12See https://www.epa.gov/air-trends/air-qualitydesign-values. 

13See section 5.4 of PM2.5 post-comment 

supplemental submission to EPA found in the 

docket for this proposed rulemaking. 

shown in table 2, confirms continued 

attainment of the standard.12

E. Contingency Provisions 

CAA section 175A(d) states that a 

maintenance plan must include 

contingency provisions, as necessary, to 

ensure prompt correction of any 

violation of the relevant NAAQS which 

may occur after redesignation of the area 

to attainment. As explained in the 

Calcagni memo, these contingency 

provisions are an enforceable part of the 

federally approved SIP. The 

maintenance plan should clearly 

identify the events that would ‘‘trigger’’ 

the adoption and implementation of a 

contingency provision, the contingency 

provision(s) that would be adopted and 

implemented, and the schedule 

indicating the timeframe by which the 

state would adopt and implement the 

provision(s). The Calcagni memo states 

that EPA will determine the adequacy of 

a contingency plan on a case-by-case 

basis. At a minimum, the plan must 

require that the state implement all 

measures contained in the CAA part D 

nonattainment plan for the area prior to 

redesignation. 

CT DEEP will continue to adhere to 

the contingency plan they submitted 

with their first maintenance plan, which 

includes the required contingency 

provisions to ensure the area will 

promptly correct any violation of the 

2006 PM2.5 NAAQS.13 Connecticut’s 

contingency measures include a 

Warning Level Response and an Action 

Level Response. CT DEEP also commits 

to pursuing adoption (and submittal to 

EPA) and implementation of any 

appropriate regulatory revisions within 

18 to 24 months after the verified 

violation. CT DEEP will select 

contingency measures based on cost 

effectiveness, emission reduction 

potential, economic and social 

considerations, or other appropriate 

factors. Stakeholder input will be 

solicited before final selection of any 

contingency measures. The contingency 

measures are described in detail in the 

NPRM for the first maintenance plan 

and will not be repeated here. See 78 FR 

43096. EPA proposes to find that the 

contingency provisions in the PM2.5

LMP for the New Haven-Fairfield 2006 

PM2.5 maintenance area meet the 

requirements of section 175A(d) of the 

CAA. 

IV. Proposed Action 

EPA is proposing to approve the 

second 10-year PM2.5 LMP for the New 

Haven-Fairfield 2006 24-hour PM2.5

maintenance area submitted by CT 

DEEP on May 9, 2023, and 

supplemented on February 21, 2024. 

EPA’s review of the air quality data for 

the maintenance area indicates that it 

continues to show attainment well 

below the level of the 2006 24-hour 

PM2.5 NAAQS and meet all the LMP 

qualifying criteria as described in this 

action. If finalized, EPA’s approval of 

this LMP will satisfy the CAA section 

175A requirements for the second 10- 

year maintenance period. 

As discussed previously, EPA is also 

initiating as part of this proposed 

rulemaking the process to determine if 

the LMP is adequate for transportation 

conformity purposes. Any comments on 

the adequacy of the submitted CT LMP 

should be submitted to the docket 

established for this rulemaking. EPA 

may complete that process either in a 

final action on this LMP or through a 

separate process provided for in the 

transportation conformity regulations. 

See 40 CFR 93.118(f). EPA is soliciting 

public comments on the issues 

discussed in this notice or on other 

relevant matters. These comments will 

be considered before taking final action. 

Interested parties may participate in the 

Federal rulemaking procedure by 

submitting written comments to this 

proposed rule by following the 

instructions listed in the ADDRESSES

section of this Federal Register. 

V. Statutory and Executive Order 

Reviews 

Under the Clean Air Act, the 

Administrator is required to approve a 

SIP submission that complies with the 

provisions of the Act and applicable 

Federal regulations. See 42 U.S.C. 

7410(k); 40 CFR 52.02(a). Thus, in 

reviewing SIP submissions, EPA’s role 

is to approve state choices, provided 

that they meet the criteria of the Clean 

Air Act. Accordingly, this proposed 

action merely approves state law as 

meeting Federal requirements and does 

not impose additional requirements 

beyond those imposed by state law. For 

that reason, this proposed action: 

• Is not a significant regulatory action 

subject to review by the Office of 

Management and Budget under 

Executive Orders 12866 (58 FR 51735, 

October 4, 1993) and 13563 (76 FR 3821, 

January 21, 2011); 

• Does not impose an information 

collection burden under the provisions 

of the Paperwork Reduction Act (44 

U.S.C. 3501 et seq.); 

• Is certified as not having a 

significant economic impact on a 

substantial number of small entities 

under the Regulatory Flexibility Act (5 

U.S.C. 601 et seq.); 

• Does not contain any unfunded 

mandate or significantly or uniquely 

affect small governments, as described 

in the Unfunded Mandates Reform Act 

of 1995 (Pub. L. 104–4); 

• Does not have federalism 

implications as specified in Executive 

Order 13132 (64 FR 43255, August 10, 

1999); 

• Is not an economically significant 

regulatory action based on health or 

safety risks subject to Executive Order 

13045 (62 FR 19885, April 23, 1997); 

• Is not a significant regulatory action 

subject to Executive Order 13211 (66 FR 

28355, May 22, 2001); and 

• Is not subject to requirements of 

section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (15 U.S.C. 272 note) because 

application of those requirements would 

be inconsistent with the Clean Air Act. 

In addition, the SIP is not approved 

to apply on any Indian reservation land 

or in any other area where EPA or an 

Indian tribe has demonstrated that a 

tribe has jurisdiction. In those areas of 

Indian country, the rule does not have 

tribal implications and will not impose 

substantial direct costs on tribal 

governments or preempt tribal law as 

specified by Executive Order 13175 (65 

FR 67249, November 9, 2000). 

Executive Order 12898 (Federal 

Actions to Address Environmental 

Justice in Minority Populations and 

Low-Income Populations, 59 FR 7629, 

Feb. 16, 1994) directs Federal agencies 

to identify and address 

‘‘disproportionately high and adverse 

human health or environmental effects’’ 

of their actions on communities with 

environmental justice (EJ) concerns to 

the greatest extent practicable and 

permitted by law. EPA defines EJ as 

‘‘the fair treatment and meaningful 

involvement of all people regardless of 

race, color, national origin, or income 

with respect to the development, 

implementation, and enforcement of 

environmental laws, regulations, and 

policies.’’ EPA further defines the term 

fair treatment to mean that ‘‘no group of 

people should bear a disproportionate 

burden of environmental harms and 

risks, including those resulting from the 

negative environmental consequences of 

industrial, governmental, and 

commercial operations or programs and 

policies.’’ 

CT DEEP did not evaluate 

environmental justice considerations as 

part of its SIP submittal; the CAA and 

applicable implementing regulations 


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1The design value is the metric used for 

determining compliance with the SO2 NAAQS 

under appendix T of 40 CFR part 50. 

neither prohibit nor require such an 

evaluation. EPA did not perform an EJ 

analysis and did not consider EJ in this 

action. Due to the nature of the action 

being taken here, this action is expected 

to have a neutral to positive impact on 

the air quality of the affected area. 

Consideration of EJ is not required as 

part of this action, and there is no 

information in the record inconsistent 

with the stated goal of E.O. 12898 of 

achieving environmental justice for 

communities with EJ concerns. 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Incorporation by 

reference, Nitrogen dioxide, Particulate 

matter, Sulfur oxides, Volatile organic 

compounds. 

Dated: September 23, 2024. 

David Cash, 

Regional Administrator, EPA Region 1. 

[FR Doc. 2024–22114 Filed 9–26–24; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R10–OAR–2024–0371; FRL–12159– 

01–R10] 

Designation of Areas for Air Quality 

Planning Purposes; Redesignation 

Request and Associated Maintenance 

Plan for Whatcom County, WA 2010 

SO2 Nonattainment Area 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: On July 25, 2024, the State of 

Washington (WA) submitted a request 

for the Environmental Protection 

Agency (EPA) to redesignate to 

attainment a portion of Whatcom 

County immediately surrounding the 

now permanently closed aluminum 

smelter, Intalco Aluminum LLC, which 

the EPA designated nonattainment for 

the 2010 sulfur dioxide (SO2) primary 

National Ambient Air Quality Standard 

(NAAQS). Washington also submitted a 

request for the EPA to approve a State 

Implementation Plan (SIP) revision 

containing a maintenance plan for the 

area. In response to this submittal, the 

EPA is proposing to take the following 

actions: determine that the Whatcom 

County (partial) SO2 nonattainment area 

(NAA) is attaining the 2010 SO2 primary 

NAAQS; approve Washington’s plan for 

maintaining attainment of the 2010 SO2

primary NAAQS in the area; and 

redesignate the Whatcom County 

(partial) SO2 NAA to attainment for the 

2010 1-hour primary SO2 NAAQS. 

DATES: Written comments must be 

received on or before October 28, 2024. 

ADDRESSES: Submit your comments, 

identified by Docket ID No. EPA–R10– 

OAR–2024–0371 at https://

www.regulations.gov. For comments 

submitted at regulations.gov, follow the 

online instructions for submitting 

comments. Once submitted, comments 

cannot be edited or removed from 

regulations.gov. For either manner of 

submission, the EPA may publish any 

comment received to its public docket. 

Do not submit electronically any 

information you consider to be 

confidential business information or 

other information the disclosure of 

which is restricted by statute. 

Multimedia submissions (audio, video, 

etc.) must be accompanied by a written 

comment. The written comment is 

considered the official comment and 

should include discussion of all points 

you wish to make. The EPA will 

generally not consider comments or 

comment contents located outside of the 

primary submission (i.e., on the web, 

cloud, or other file sharing system). For 

additional submission methods, please 

contact the person identified in the FOR

FURTHER INFORMATION CONTACT section. 

For the full EPA public comment policy, 

information about confidential business 

information or multimedia submissions, 

and general guidance on making 

effective comments, please visit https:// 

www.epa.gov/dockets/commenting-epadockets. 

FOR FURTHER INFORMATION CONTACT: Jeff 

Hunt, EPA Region 10, 1200 Sixth 

Avenue, Suite 155, Seattle, WA 98101, 

at (206) 553–6357 or hunt.jeff@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Throughout this document, the use of 

‘‘we’’ and ‘‘our’’ means the EPA. 

I. What is the background for the EPA’s 

proposed actions? 

On June 22, 2010, the EPA published 

a new 1-hour primary SO2 NAAQS of 75 

parts per billion (ppb), which is met at 

an ambient air quality monitoring site 

when the 3-year average of the annual 

99th percentile of daily maximum 1- 

hour average concentrations does not 

exceed 75 parts per billion (ppb), as 

determined in accordance with 

appendix T of 40 CFR part 50 (75 FR 

35520). Under Clean Air Act (CAA) 

section 107(d)(1), the EPA is required to 

designate areas as ‘‘nonattainment,’’ 

‘‘attainment,’’ or ‘‘unclassifiable’’ within 

two years of establishing a new or 

revising an existing standard. As part of 

this process, states must submit 

recommendations for area designations 

and boundaries to the EPA within one 

year of the effective date of the standard. 

In 2011, Washington State, like many 

states across the nation, did not have 

sufficient SO2 monitoring data for 

specific stationary sources that may 

cause or contribute to violations of the 

revised SO2 NAAQS and recommended 

that all areas in the state be designated 

as unclassifiable. In response to the lack 

of sufficient SO2 monitoring data across 

the nation, the EPA promulgated the 

Data Requirements Rule (DRR) on 

August 21, 2015 (80 FR 51052), which 

established a phased-in approach for 

state air agencies to characterize air 

quality via additional monitoring or 

modeling in areas associated with 

sources meeting certain criteria. In 

addition to the original round of 

nonattainment designations published 

on August 5, 2013 (78 FR 47191), the 

EPA promulgated three subsequent 

rounds of designations in 2016 (81 FR 

45039, July 12, 2016), 2018 (83 FR1098, 

January 9, 2018), and 2021 (86 FR 

16055, March 26, 2021), as information 

to characterize air quality became 

available. The EPA designated Whatcom 

County (partial), Washington (also 

referred to as the ‘‘nonattainment area’’ 

or ‘‘area’’) as nonattainment effective 

April 30, 2021, as part of the Agency’s 

Round 4 designations (86 FR 16055, 

March 26, 2021). 

In the case of Washington, the EPA 

and the Washington Department of 

Ecology (Ecology) identified the Alcoa 

Intalco Aluminum LLC (Intalco) facility, 

located in the Cherry Point Industrial 

Area in Whatcom County, as emitting 

2,000 tons or more of SO2 annually, 

which triggered the DRR requirement 

for additional modeling or monitoring to 

characterize air quality in the area. 

Washington chose to meet this DRR 

requirement via the establishment of 

monitoring at the Intalco facility 

beginning on January 1, 2017. Based on 

the monitoring data established under 

the DRR, the Ferndale Mountain View 

Road monitor (AQS ID 53–073–0017) 

violated the 75 ppb level of the revised 

1-hour primary SO2 NAAQS with a 

2017–2019 design value of 106 ppb.1

The state did not send an updated 

formal designation recommendation for 

Whatcom County. However, Ecology, in 

collaboration with Northwest Clean Air 

Agency (NWCAA), submitted a 

technical report and modeling analysis 

on June 12, 2020, to help inform the 

EPA’s nonattainment boundary 

determination using data from the 

monitors that were installed pursuant to 


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