Federal Register / Vol. 89, No. 188 / Friday, September 27, 2024 / Proposed Rules 79195 

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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2See 202_Intalco Sulfur Dioxide Attainment 

Plan_2202035.pdf, included in the docket for this 

action. 

3See Appendix A of state submittal included in 

the docket for this action. 

4 Id, November 30, 2023, from James DeMay to 

Tia Daulph, ‘‘Termination of Title V Air Operating 

Permit No. 0002950 and Notice of Construction 

Orders, Compliance Orders, and Agreed Orders’’ 

and December 7, 2023, from Tia Daulph to James 

DeMay, ‘‘Re: Termination of Title V Air Operating 

Permit No. 0002950’’ included in the docket for this 

action. 5See 2014 SO2 NAA Guidance, at 62. 

the DRR. Given that the state did not 

provide a formal recommendation for 

the boundary, the EPA conducted an 

extensive review of the submitted 

modeling to develop sufficient evidence 

to support the determination of a 

nonattainment boundary. The 

nonattainment boundary must contain 

all of the area where the NAAQS are not 

attained and all areas that contribute to 

the violations. Based on our review, the 

EPA determined that the state’s 

modeling assessment was reliable for 

determining the extent of the area of 

violation of the 1-hour primary SO2

NAAQS. Specifically, we agreed that the 

region of violation was most likely due 

to plume downwash at the Intalco 

facility during certain wind conditions, 

that the modeled area of violation did 

not extend far from the Intalco facility 

fence line, that the gradient of 

concentration near the areas of violation 

was steep, quickly dropping with 

distance from the Intalco facility fence 

line, and that other nearby industrial 

facilities did not sufficiently contribute 

to violations of the 1-hour primary SO2

NAAQS to warrant inclusion in the 

NAA boundary. In our final 

nonattainment boundary determination, 

we concurred with Ecology and 

NWCAA’s view that the boundary 

should be drawn to encompass the 

cause of the SO2 violations, the Intalco 

facility. However, we used a simpler 

nonattainment boundary consisting of 

four Universal Transverse Mercator 

(UTM) coordinates instead of the 

various roadways and property lines 

suggested by NWCAA in a June 9, 2020, 

letter. For more information about the 

specific modeling and the EPA’s 

analysis, please see ‘‘Appendix A 

Whatcom County SO2 Area 

Designation’’ included in the docket for 

this action. 

In response to the EPA’s designation 

of the NAA, Washington submitted an 

attainment plan on December 15, 2022, 

to the EPA for approval. This plan and 

associated order required significant 

upgrades to the Intalco facility 

including installation and operation of a 

new SO2 wet scrubber.2 Subsequently, 

on March 16, 2023, Alcoa Corporation 

publicly announced their plans to 

permanently close the Intalco facility.3

Ecology issued a notice of intent to 

revoke the associated minor new source 

review (NSR) and Title V Operating 

Permits on November 30, 2023, which 

became effective December 7, 2023.4

Under Revised Code of Washington 

(RCW) and Washington Administrative 

Code (WAC), Intalco cannot operate the 

facility without first obtaining a new 

Title V operating permit and applicable 

NSR permits, including a demonstration 

of compliance with the 2010 1-hour SO2

NAAQS. Since the 2022 attainment 

plan, which imposed specific control 

requirements on Intalco, became 

functionally moot with the 2023 

permanent closure of the facility, 

Ecology proceeded directly to 

submitting a redesignation request and 

maintenance plan for the area. Upon the 

EPA’s final approval of the 

redesignation request and maintenance 

plan for the area, Ecology intends to 

withdraw the now outdated 2022 

attainment plan. The EPA is not 

proposing to act on the 2022 attainment 

plan in this action. 

II. What are the criteria for 

redesignation? 

The CAA provides the requirements 

for redesignating a NAA to attainment. 

Specifically, section 107(d)(3)(E) of the 

CAA allows for redesignation of a NAA 

provided that: (1) the Administrator 

determines that the area has attained the 

applicable NAAQS; (2) the 

Administrator has fully approved the 

applicable implementation plan for the 

area under section 110(k); (3) the 

Administrator determines that the 

improvement in air quality is due to 

permanent and enforceable reductions 

in emissions resulting from 

implementation of the applicable SIP 

and applicable Federal air pollutant 

control regulations and other permanent 

and enforceable reductions; (4) the 

Administrator has fully approved a 

maintenance plan for the area as 

meeting the requirements of section 

175A; and (5) the State containing such 

area has met all requirements applicable 

to the area for purposes of redesignation 

under section 110 and part D of the 

CAA. 

On April 16, 1992, the EPA provided 

guidance on redesignation in the 

General Preamble for the 

Implementation of title I of the CAA 

Amendments of 1990 (57 FR 13498) and 

supplemented this guidance on April 

28, 1992 (57 FR 18070). The EPA has 

provided further guidance on processing 

redesignation requests in several 

guidance documents. For the purposes 

of this action, the EPA will be 

referencing two of these documents: (1) 

the September 4, 1992, Memorandum 

from John Calcagni titled ‘‘Procedures 

for Processing Requests to Redesignate 

Areas to Attainment,’’ (hereafter referred 

to as the ‘‘Calcagni Memo’’); and (2) the 

April 23, 2014, Memorandum from 

Stephen D. Page titled ‘‘Guidance for 1- 

Hour SO2 Nonattainment Area SIP 

Submissions,’’ (hereafter referred to as 

‘‘2014 SO2 NAA Guidance’’). 

III. What is the EPA’s analysis of the 

request? 

The EPA’s evaluation of Washington’s 

redesignation request and maintenance 

plan was based on consideration of the 

five redesignation criteria provided 

under CAA section 107(d)(3)(E). 

Criteria (1)—The Whatcom County 

(Partial) SO2 Nonattainment Area Has 

Attained the 2010 1-Hour SO2 NAAQS 

For redesignating a NAA, the CAA 

requires the EPA to determine that the 

area has attained the applicable NAAQS 

(CAA section 107(d)(3)(E)(i)). The two 

primary methods for evaluating ambient 

air quality impacted by SO2 emissions 

are through dispersion modeling and air 

quality monitoring. For SO2, an area 

may be considered attaining the 2010 1- 

hour SO2 NAAQS if it meets the 

NAAQS as determined in accordance 

with 40 CFR 50.17 and appendix T of 

part 50, based on three complete, 

consecutive calendar years of qualityassured air quality monitoring data. To 

attain the NAAQS based on monitoring, 

the 3-year average of the annual 99th 

percentile (fourth highest value) of 1- 

hour daily maximum concentrations 

measured at each monitor within an 

area must be less than or equal to 75 

ppb. The data must be collected and 

quality-assured in accordance with 40 

CFR part 58 and recorded in the EPA 

Air Quality System (AQS). The EPA’s 

determination of attainment can be 

based on monitoring data alone, without 

the need for dispersion modeling 

analyses, if the air agency provides an 

analysis demonstrating that the 

monitor(s) for the affected area is 

located in the area of maximum ambient 

concentration of SO2.5

In this action, the EPA is proposing to 

determine that the Whatcom County 

(partial) SO2 nonattainment area is 

attaining the 2010 1-hour SO2 NAAQS. 

The EPA reviewed SO2 monitoring data 

from the two monitoring stations inside 

the Whatcom County (partial) SO2

nonattainment area, the FerndaleMountain View Road station (AQS Site 


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6Whatcom County (partial) redesignation request, 

at pages 20–22. 7AERMOD is one of the EPA’s preferred and 

recommended dispersion models listed in the 

Guideline on Air Quality Models—Appendix W to 

be used for State Implementation Plan (SIP) 

revisions for existing sources and for New Source 

Review (NSR) and Prevention of Significant 

Deterioration (PSD) programs. See https://

www.epa.gov/scram/air-quality-dispersionmodeling-preferred-and-recommended-models. 

8See 201_Appendix A Whatcom County SO2

Area Designation and 203 Appendix C Intalco SO2

Attainment Modeling Report, included in the 

docket for this action. 

9 Id. 

10See 2014 SO2 NAA Guidance, at 56. 11 Id. at 52. 

ID 53–073–0017) and the FerndaleKickerville Road station (AQS Site ID 

53–073–0013). The monitoring station 

data have been quality-assured, are 

recorded in the EPA’s Air Quality 

System (AQS), and indicate that the area 

is attaining the 2010 1-hour SO2

NAAQS. The fourth-highest 1-hour SO2

values at the monitoring stations for the 

3-year averages of these values (i.e., 

design values), are summarized in Table 

1, below. 

TABLE 1—WHATCOM COUNTY (PARTIAL) MONITORED SO2 CONCENTRATIONS

[ppb] 

Station 2021 99th 

Percentile 

2022 99th 

Percentile 

2023 99th 

Percentile 

2021–2023 

Design value 

Ferndale-Mountain View Road .............................................................................. 2.6 3.3 4.4 3 

Ferndale-Kickerville Road ...................................................................................... 2.4 3.1 4.4 3 

As shown, the 3-year design values 

for 2021–2023 at the monitoring stations 

are well below the 2010 1-hour SO2

NAAQS. Concentrations of SO2 at these 

monitoring stations decreased 

significantly from the 2017–2019 design 

value of 106 ppb following the 

shutdown of the Intalco facility. Since 

the facility last operated in July 2020, 

99th percentile values at the monitoring 

stations have not exceeded 4.4 ppb SO2. 

These low values are anticipated to be 

consistent, as the state demonstrated in 

its analysis that SO2 emissions since 

2020 have consistently decreased to 

levels well below the 2010 1-hour SO2

NAAQS during both curtailment and 

permanent closure of the Intalco 

facility.6

As part of Washington’s 2022 

attainment plan and 2024 redesignation 

request, Ecology submitted information 

to support a showing that the FerndaleMountain View Road monitor was sited 

in the area of maximum ambient SO2

concentration within the Whatcom 

County (partial) SO2 NAA in accordance 

with the 2014 SO2 NAA Guidance. 

Ecology identified appropriate locations 

for the two Ferndale monitors in 2015 

by running the AERMOD 7 dispersion 

model using SO2 actual emissions from 

Intalco.8 The EPA reviewed 

Washington’s information regarding this 

showing in designating the area 

nonattainment in Round 4. We found 

that the state’s modeling assessment was 

reliable for determining the extent of the 

area of violation of the 1-hour SO2

NAAQS. Specifically, we agreed that the 

region of violation was most likely due 

to plume downwash at the Intalco 

facility during certain wind conditions, 

that the modeled area of violation does 

not extend far from the Intalco facility 

fenceline, that the gradient of 

concentration near the areas of violation 

is steep, quickly dropping with distance 

from the Intalco facility fenceline, and 

that other nearby industrial facilities do 

not sufficiently contribute to violations 

of the SO2 NAAQS to warrant inclusion 

in the nonattainment area boundary.9

With Intalco permanently closed, 

monitored SO2 concentrations in the 

Whatcom County (partial) SO2

nonattainment area are well below the 

75 ppb standard. 

In this action, the EPA is proposing to 

determine that the Whatcom County 

(partial) SO2 nonattainment area is 

attaining the 2010 1-hour SO2 NAAQS, 

and therefore meets the requirements of 

CAA section 107(d)(3)(E)(i). If the 3-year 

design value exceeds the NAAQS prior 

to the EPA taking action in response to 

the state’s request, the EPA will not take 

final action to approve the redesignation 

request.10

Because the EPA’s analysis in 

determining whether an area has 

attained under the clean data policy is 

the same as its analysis under the first 

redesignation criterion, the EPA is also 

here proposing that the Whatcom 

County (partial) SO2 nonattainment area 

qualifies for a determination of 

attainment under the clean data policy, 

based on the 2021–2023 monitoring data 

at the two Ferndale monitoring stations. 

The clean data policy represents the 

EPA’s interpretation that certain 

requirements of part D of title I of the 

Act are suspended for areas that are 

currently attaining the NAAQS. The 

requirements that are suspended in an 

area attaining the standard include the 

requirements to submit an ‘‘attainment 

SIP’’ that provides for: attainment of the 

NAAQS; implementation of all 

reasonably available control measures 

(RACM); reasonable further progress 

(RFP); and implementation of 

contingency measures for failure to meet 

deadlines for RFP and attainment. In the 

2014 SO2 NAA Guidance, the EPA 

explained our intention to apply the 

EPA’s clean data policy to the 2010 SO2

primary NAAQS.11

In the event that the EPA does not 

finalize the proposed redesignation, the 

EPA may choose to finalize the clean 

data determination, thereby suspending 

attainment planning-related 

requirements for the area for as long as 

the area continues to attain the 

standard. 

Criteria (2)—Washington Has a Fully 

Approved SIP Under Section 110(k) and 

Criteria (5)—Washington Has Met All 

Applicable Requirements Under Section 

110 and Part D of Title I of the CAA 

For redesignating a nonattainment 

area to attainment under a NAAQS, the 

CAA requires the EPA to determine that 

the state has met all applicable 

requirements for that NAAQS under 

section 110 and part D of title I of the 

CAA (CAA section 107(d)(3)(E)(v)) and 

that the state has a fully approved SIP 

under section 110(k) for that NAAQS for 

the area (CAA section 107(d)(3)(E)(ii)). 

The EPA proposes to find that 

Washington has met all applicable SIP 

requirements for the Whatcom County 

(partial) SO2 nonattainment area for the 

2010 SO2 NAAQS under section 110 of 

the CAA (general SIP requirements) for 

purposes of redesignation. Additionally, 

the EPA proposes to find that the 

Washington SIP satisfies the criterion 

that it meets applicable SIP 

requirements for purposes of 

redesignation under part D of title I of 

the CAA in accordance with section 

107(d)(3)(E)(v). Further, the EPA 

proposes to determine that the SIP is 

fully approved with respect to all 

requirements applicable for the 2010 

SO2 NAAQS for purposes of 

redesignation in accordance with 

section 107(d)(3)(E)(ii). In making the 

determinations, the EPA ascertained 


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which requirements are applicable to 

the Whatcom County (partial) SO2

nonattainment area and, if applicable, 

that they are fully approved under 

section 110(k). 

a. The Whatcom County (Partial) SO2

Nonattainment Area Has Met All 

Applicable Requirements Under Section 

110 and Part D of the CAA 

General SIP Requirements. General 

SIP elements and requirements are 

delineated in section 110(a)(2) of title I, 

part A of the CAA. These requirements 

include, but are not limited to, the 

following: submittal of a SIP that has 

been adopted by the state after 

reasonable public notice and hearing; 

provisions for establishment and 

operation of appropriate procedures 

needed to monitor ambient air quality; 

implementation of a source permit 

program; provisions for the 

implementation of part C requirements 

(Prevention of Significant Deterioration 

(PSD)) and provisions for the 

implementation of part D requirements 

(New Source Review (NSR) permit 

programs); provisions for air pollution 

modeling; and provisions for public and 

local agency participation in planning 

and emission control rule development. 

Section 110(a)(2)(D) requires that SIPs 

contain certain measures to prevent 

sources in a state from significantly 

contributing to air quality problems in 

another state. To implement this 

provision, the EPA has required certain 

states to establish programs to address 

the interstate transport of air pollutants. 

The section 110(a)(2)(D) requirements 

for a state are not linked with a 

particular nonattainment area’s 

designation and classification in that 

state. The EPA believes that the 

requirements linked with a particular 

nonattainment area’s designation and 

classifications are the relevant measures 

to evaluate in reviewing a redesignation 

request. The transport SIP submittal 

requirements, where applicable, 

continue to apply to a state regardless of 

the designation of any one particular 

area in the state. Thus, the EPA does not 

believe that the CAA’s interstate 

transport requirements should be 

construed to be applicable requirements 

for purposes of redesignation. 

In addition, the EPA believes other 

section 110 elements that are neither 

connected with nonattainment plan 

submissions nor linked with an area’s 

attainment status are applicable 

requirements for purposes of 

redesignation. The area will still be 

subject to these requirements after the 

area is redesignated. The section 110 

and part D requirements which are 

linked with a particular area’s 

designation and classification are the 

relevant measures to evaluate in 

reviewing a redesignation request. This 

approach is consistent with the EPA’s 

existing policy on applicability (i.e., for 

redesignations) of conformity and 

oxygenated fuels requirements, as well 

as with section 184 ozone transport 

requirements. See Reading, 

Pennsylvania, proposed and final rules 

(61 FR 53174–53176, October 10, 1996), 

(62 FR 24826, May 7, 2008); ClevelandAkron-Loraine, Ohio, final rule (61 FR 

20458, May 7,1996); and Tampa, 

Florida, final rule (60 FR 62748, 

December 7, 1995). See also the 

discussion on this issue in the 

Cincinnati, Ohio, redesignation (65 FR 

37890, June 19, 2000), and in the 

Pittsburgh, Pennsylvania, redesignation 

(66 FR 0399, October 19, 2001). 

Title I, Part D, Applicable SIP 

Requirements. Section 172(c) of the 

CAA sets forth the basic requirements of 

attainment plans for NAAs that are 

required to be submitted pursuant to 

section 172(b). Subpart 5 of part D, 

which includes section 191 and 192 of 

the CAA, establishes requirements for 

SO2, nitrogen dioxide and lead NAAs. A 

thorough discussion of the requirements 

contained in sections 172(c) can be 

found in the General Preamble for 

Implementation of Title I (57 FR 13498, 

April 16, 1992). 

Section 172(c)(1) requires the plans 

for all NAAs to provide for the 

implementation of all RACM as 

expeditiously as practicable and to 

provide for attainment of the NAAQS. 

The EPA interprets this requirement to 

impose a duty on all nonattainment 

areas to consider all available control 

measures and to adopt and implement 

such measures as are reasonably 

available for implementation in each 

area as components of the area’s 

attainment demonstration. Under 

section 172, states with nonattainment 

areas must submit plans providing for 

timely attainment and meeting a variety 

of other requirements. 

The EPA’s longstanding interpretation 

of the nonattainment planning 

requirements of section 172 is that once 

an area is attaining the NAAQS, those 

requirements are not ‘‘applicable’’ for 

purposes of CAA sections 

107(d)(3)(E)(ii) and (v) and therefore, 

need not be approved into the SIP 

before the EPA can redesignate the area. 

In the 1992 General Preamble for 

Implementation of Title I, the EPA set 

forth its interpretation of applicable 

requirements for purposes of evaluating 

redesignation requests when an area is 

attaining a standard. See 57 FR 13498, 

13564 (April 16, 1992). The EPA noted 

that the requirements for RFP and other 

measures designed to provide for 

attainment do not apply in evaluating 

redesignation requests because those 

nonattainment planning requirements 

‘‘have no meaning’’ for an area that has 

already attained the standard. Id. This 

interpretation was also reiterated in the 

1992 Calcagni Memo and consistently 

applied in many proposed and final 

redesignation actions since. The EPA’s 

understanding of section 172 also forms 

the basis of its Clean Data Policy, which 

was articulated with regard to SO2 in 

the 2014 SO2 NAA Guidance and 

suspends a state’s obligation to submit 

most of the attainment planning 

requirements that would otherwise 

apply, including an attainment 

demonstration and planning SIPs to 

provide for RFP, RACM, and 

contingency measures under section 

172(c)(9). Courts have upheld the EPA’s 

interpretation of section 172(c)(1) for 

‘‘reasonably available’’ control measures 

and control technology as meaning only 

those controls that advance attainment, 

which precludes the need to require 

additional measures where an area is 

already attaining. NRDC v. EPA, 571 

F.3d 1245, 1252 (D.C. Cir. 2009); Sierra 

Club v. EPA, 294 F.3d 155, 162 (D.C. 

Cir. 2002); Sierra Club v. EPA, 314 F.3d 

735, 744 (5th Cir. 2002); Sierra Club v. 

EPA, 375 F.3d 537 (7th Cir. 2004). But 

see Sierra Club v. EPA, 793 F.3d 656 

(6th Cir. 2015). 

Therefore, because the design values 

for 2021–2023 are well below the 

NAAQS in the Whatcom County 

(partial) SO2 NAA, no additional 

measures are needed to provide for 

attainment, and section 172(c)(1) 

requirements for an attainment 

demonstration and RACM are not part 

of the ‘‘applicable implementation 

plan’’ required to have been approved 

prior to redesignation per CAA section 

107(d)(3)(E)(ii). The other section 172 

requirements that are designed to help 

an area achieve attainment—the section 

172(c)(2) requirement that 

nonattainment plans contain provisions 

promoting reasonable further progress, 

the requirement to submit the section 

172(c)(9) contingency measures that 

would apply if the area fails to timely 

attain, and the section 172(c)(6) 

requirement for the SIP to contain 

control measures necessary to provide 

for attainment of the NAAQS—are also 

not required to be approved as part of 

the ‘‘applicable implementation plan’’ 

for purposes of satisfying CAA section 

107(d)(3)(E)(ii). 

Section 172(c)(3) requires submission 

and approval of a comprehensive, 

accurate, and current inventory of actual 

emissions. The requirement for an 

emission inventory can be satisfied by 


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12Calcagni Memo at 6. 

13See EPA’s final Technical Support Document 

(TSD) for the Whatcom County (partial) SO2

nonattainment area, included in the docket for this 

action. See 201_Appendix A Whatcom County SO2

Area Designation.pdf. 

14Calcagni Memo at 10. 

15Ecology’s November 30, 2023, permit 

revocation letter is included in appendix A of the 

redesignation request, included in the docket for 

this action. 

meeting the inventory requirements of 

the maintenance plan.12 Ecology 

submitted an emissions inventory as 

part of the maintenance plan for the 

Whatcom County (partial) SO2

nonattainment area, and this inventory 

will be discussed further in the 

maintenance plan portion of this 

proposed action. 

Section 172(c)(4) requires the 

identification and quantification of 

allowable emissions for major new and 

modified stationary sources to be 

allowed in an area, and section 172(c)(5) 

requires source permits for the 

construction and operation of new and 

modified major stationary sources 

anywhere in the nonattainment area. 

The EPA has determined that, since PSD 

requirements will apply after 

redesignation, areas being redesignated 

need not comply with the requirement 

that a NSR program be approved prior 

to redesignation, provided that the area 

demonstrates maintenance of the 

NAAQS without part D NSR. A more 

detailed rationale for this view is 

described in a memorandum from Mary 

Nichols, Assistant Administrator for Air 

and Radiation, dated October 14, 1994, 

entitled ‘‘Part D New Source Review 

Requirements for Areas Requesting 

Redesignation to Attainment.’’ Ecology 

has demonstrated that the Whatcom 

County (partial) SO2 nonattainment area 

will be able to maintain the NAAQS 

without part D NSR in effect, and 

therefore Washington need not have 

fully approved part D NSR programs 

prior to approval of the redesignation 

request. Nevertheless, we note that 

Washington’s nonattainment NSR for 

major sources was last approved by the 

EPA on October 6, 2016 (81 FR 69386) 

and the NWCAA’s nonattainment NSR 

for minor sources was last approved by 

the EPA on June 5, 2020 (85 FR 36156). 

Both programs meet all relevant NSR 

requirements for SO2. Washington’s PSD 

program for major sources will become 

effective in the Whatcom County 

(partial) SO2 nonattainment area upon 

redesignation to attainment. Section 

172(c)(7) requires the SIP to meet the 

applicable provisions of section 

110(a)(2). As noted above, the EPA 

believes the Washington SIP meets the 

requirements of section 110(a)(2) 

applicable for purposes of 

redesignation. 

Section 176 Conformity 

Requirements. Section 176(c) of the 

CAA requires states to establish criteria 

and procedures to ensure that federally 

supported or funded projects conform to 

the air quality planning goals in the 

applicable SIP. The requirement to 

determine conformity applies to 

transportation plans, programs, and 

projects that are developed, funded, or 

approved under title 23 of the United 

States Code (U.S.C.) and the Federal 

Transit Act (transportation conformity) 

as well as to all other federally 

supported or funded projects (general 

conformity). State transportation 

conformity SIP revisions must be 

consistent with Federal conformity 

regulations relating to consultation, 

enforcement, and enforceability that the 

EPA promulgated pursuant to its 

authority under the CAA. 

The EPA interprets the conformity SIP 

requirements as not applying for 

purposes of evaluating a redesignation 

request under section 107(d) because, 

like other requirements listed above, 

state conformity rules are still required 

after redesignation and Federal 

conformity rules apply where state rules 

have not been approved. See Wall v. 

EPA, 265 F.3d 426 (6th Cir. 2001) 

(upholding this interpretation); see also 

60 FR 62748 (December 7, 1995) 

(redesignation of Tampa, Florida). 

For these reasons, the EPA proposes 

to find that Washington has satisfied all 

applicable requirements for purposes of 

redesignation of the Whatcom County 

(partial) SO2 nonattainment area under 

section 110 and part D of title I of the 

CAA. 

b. The Whatcom County (Partial) SO2

Nonattainment Area Has a Fully 

Approved Applicable SIP Under Section 

110(k) of the CAA 

The EPA has fully approved the 

applicable Washington SIP for the 

Whatcom County (partial) area under 

section 110(k) of the CAA for all 

requirements applicable for purposes of 

redesignation. As indicated above, the 

EPA believes that the section 110 

elements that are neither connected 

with nonattainment plan submissions 

nor linked to an area’s nonattainment 

status are not applicable requirements 

for purposes of redesignation. The EPA 

has approved all part D requirements 

applicable under the 2010 SO2 NAAQS, 

as identified above, for purposes of this 

redesignation. 

Criteria (3)—The Air Quality 

Improvement in the Whatcom County 

(Partial) SO2 Nonattainment Area Is 

Due to Permanent and Enforceable 

Reductions in Emissions 

For redesignating a nonattainment 

area to attainment, the CAA requires the 

EPA to determine that the air quality 

improvement in the area is due to 

permanent and enforceable reductions 

in emissions resulting from 

implementation of the SIP, applicable 

Federal air pollution control 

regulations, and other permanent and 

enforceable reductions (CAA section 

107(d)(3)(E)(iii)). The EPA proposes to 

find that Washington has demonstrated 

that the observed air quality 

improvement in the Whatcom County 

(partial) SO2 NAA is due to permanent 

and enforceable reductions in 

emissions. Specifically, the EPA 

considers the shutdown of the Intalco 

facility, identified as the key contributor 

to the SO2 NAAQS violations at the 

Ferndale-Mountain View Road 

monitor,13 to be both permanent and 

enforceable. Given the well-established 

correlation of much lower SO2

emissions at the two Ferndale monitors 

during periods when Intalco has not 

operated and the very low SO2

concentrations following the facility’s 

permanent shutdown, the EPA 

anticipates that the area will continue to 

attain the SO2 NAAQS. As stated in the 

Calcagni Memo, ‘‘Emission reductions 

from source shutdowns can be 

considered permanent and enforceable 

to the extent that those shutdowns have 

been reflected in the SIP and all 

applicable permits have been modified 

accordingly.’’ 14 Ecology revoked 

Alcoa’s Title V (operating) and NSR 

permits for the Intalco facility.15 The 

facility is now permanently closed, 

making its future operation impossible 

and thus displaying the permanence of 

the emissions reductions in the NAA. 

Any new sources that may come into 

being within the area would be required 

to demonstrate that their new SO2

emissions would not interfere with 

attainment and maintenance of the 2010 

1-hour primary SO2 NAAQS. Therefore, 

the EPA is proposing to find that the air 

quality improvement in the Whatcom 

County (partial) SO2 NAA is due to 

permanent and enforceable reductions 

in emissions. 

Criteria (4)—The Whatcom County 

(Partial) SO2 Nonattainment Area Has a 

Fully Approved Maintenance Plan 

Pursuant to Section 175A of the CAA 

To redesignate a NAA to attainment, 

the CAA requires the EPA to determine 

that the area has a fully approved 

maintenance plan pursuant to section 

175A of the CAA (CAA section 

107(d)(3)(E)(iv)). In conjunction with its 


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16See 2014 SO2 NAA Guidance, at 66. 17See 2014 SO2 NAA Guidance at 67. 18Calcagni Memo at 11. 

request to redesignate the Whatcom 

County (partial) SO2 nonattainment area 

to attainment for the 2010 1-hour SO2

NAAQS, Ecology submitted a SIP 

revision to provide for the maintenance 

of the 2010 1-hour SO2 NAAQS for at 

least 10 years after the effective date of 

redesignation to attainment. The EPA is 

proposing to find that this maintenance 

plan for the area meets the requirements 

for approval under section 175A of the 

CAA. 

a. What is required in a maintenance 

plan? 

CAA section 175A sets forth the 

elements of a maintenance plan for 

areas seeking redesignation from 

nonattainment to attainment. Under 

section 175A, the plan must 

demonstrate continued attainment of 

the applicable NAAQS for at least 10 

years after the Administrator approves a 

redesignation to attainment. Eight years 

after the redesignation, the state must 

submit a revised maintenance plan 

demonstrating that attainment will 

continue to be maintained for the 10 

years following the initial 10-year 

period. To address the possibility of 

future NAAQS violations, the 

maintenance plan must contain 

contingency measures as the EPA deems 

necessary to assure prompt correction of 

any future 2010 1-hour SO2 violations. 

The Calcagni Memo provides further 

guidance on the content of a 

maintenance plan, explaining that a 

maintenance plan should address five 

elements: The attainment emissions 

inventory, maintenance demonstration, 

monitoring, verification of continued 

attainment, and a contingency plan. As 

is discussed more fully below, the EPA 

is proposing to determine that 

Washington’s maintenance plan 

includes all the necessary components 

and is thus proposing to approve it as 

a revision to the Washington SIP. 

b. Attainment Emissions Inventory 

As part of a state’s maintenance plan 

for a 2010 SO2 NAA, the air agency 

should develop an attainment inventory 

to identify the level of emissions in the 

affected area which is sufficient to attain 

and maintain the SO2 NAAQS.16

Washington selected 2020 as the base 

year (i.e., attainment emissions 

inventory year) for developing an 

emissions inventory for SO2 in the NAA 

through 2033. The 2020 base year 

represents the most contemporaneous 

National Emissions Inventory (NEI) 

available. The 2020 base year also 

represents Intalco’s final year of 

operation with facility emissions of 

1,613 tons of SO2.

In the 2019–2021 monitoring period, 

representative of the base year, the 

Ferndale-Mountain View Road monitor 

had a 3-year design value of 56 ppb and 

the Ferndale-Kickerville Road monitor 

had a 3-year design value of 44 ppb, 

both below the 75 ppb concentration of 

the 1-hour SO2 NAAQS. The 2020 99th 

percentiles recorded at the two monitors 

are consistent with these low design 

values at 62.0 ppb and 59.2 ppb, 

respectively. The EPA has therefore 

determined that this is a level sufficient 

to attain the 2010 1-hour SO2 NAAQS 

and is proposing to find that the 

attainment inventory submitted as part 

of Washington’s maintenance plan 

meets the ‘‘Attainment Emissions 

Inventory’’ requirement. 

The EPA notes that the permanent 

shutdown of Intalco has left the 

Whatcom County (partial) SO2 NAA 

with no significant sources of SO2, and 

the maintenance plan for the area 

contains an emissions inventory which 

projects no significant SO2 emissions in 

the NAA from 2020 through 2033. The 

EPA therefore does not anticipate 

emissions activity in the 2010 SO2

nonattainment area that will approach 

1,613 tons of SO2. 

TABLE 2—BASE YEAR 2020 AND PROJECTION YEARS 2026 AND 2033 SO2 EMISSIONS FOR THE MAINTENANCE AREA

[Tons per year] 

Source 2020 

Base year 

2026 

Projection 

2033 

Projection 

Alcoa Primary Metals Intalco Works ........................................................................................... 1613.4000 0 0 

Residential non-wood fuel use .................................................................................................... 0.0026 0.0026 0.0026 

Residential wood combustion (home heating) ............................................................................ 0.0266 0.0266 0.0266 

On-road mobile sources .............................................................................................................. 0.0095 0.0095 0.0095 

Ships (commercial marine vessels) ............................................................................................. 0.0221 0.0221 0.0221 

Railroad (locomotives) ................................................................................................................. 0.0002 0.0002 0.0002 

Non-road mobile equipment and vehicles (NEC) ........................................................................ 0.0010 0.0010 0.0010 

Total ...................................................................................................................................... 1,613.4620 0.0620 0.0620 

c. Maintenance Demonstration 

An air agency may generally 

demonstrate maintenance of the 

NAAQS by either showing that future 

emissions of SO2 will not exceed the 

level of the attainment inventory, or by 

modeling to show that the future mix of 

sources and emission rates will not 

cause a violation of the NAAQS.17

Washington has demonstrated 

maintenance by showing that future 

year emissions (through ‘‘out year’’ 

2033) of SO2 in the maintenance area 

are expected to remain near zero 

following the Intalco shutdown. Due to 

the small geographic scope of the 

nonattainment area surrounding the 

facility boundary (4.5 square miles), 

other contributing sources such as 

mobile sources and area sources are 

nearly nonexistent and are projected to 

remain constant through 2033. The EPA 

considers the inventory projection 

sufficient to attain and maintain the SO2

NAAQS. The EPA is therefore also 

proposing to find that Washington’s 

‘‘Maintenance Demonstration’’ 

requirement is met based on this 

projected emissions inventory. 

d. Monitoring Network and Verification 

of Continued Attainment 

According to the Calcagni Memo, the 

state should continue to operate an 

appropriate air quality monitoring 

network to verify the attainment status 

of the area.18 In addition, the state must 

have the legal authority to implement 

and enforce all measures necessary to 

attain and maintain the NAAQS and the 

maintenance plan should contain 

provisions to track the progress of the 

maintenance plan. 

With respect to the monitoring 

network, Ecology maintains two SO2

monitors in the nonattainment area: 


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19 Department of Ecology, State of Washington, 

2023 Ambient Air Monitoring Network Plan, 

Publication 23–02–043, June 2023, at p. 20. 20November 16, 2023, Letter from Debra Suzuki, 

Air Planning and State/Tribal Coordination Branch, 

EPA Region 10, to Jill Schulte, Ambient Air 

Monitoring Coordinator, Department of Ecology. 

21See 201_Appendix A Whatcom County SO2

Area Designation.pdf and 202_Intalco Sulfur 

Dioxide Attainment Plan_2202035.pdf, included in 

the docket for this action. 

22Rule 300.1(A); 300.4. 

23Rule 300.9. 

24 40 CFR 52.2470(c); WAC 173–400–113 and 

WAC 173–400–700 through 173–400–750. 

Ferndale-Mountain View Road and the 

Ferndale-Kickerville Road. These 

monitors were included in Ecology’s 

2023 Ambient Air Monitoring Network 

Plan as microscale SLAMS monitors.19

EPA approved this network plan on 

November 16, 2023.20 As discussed in 

the EPA’s 2020 designation of the area 

and the 2022 attainment plan included 

in the docket for this action, the 

Ferndale-Mountain View Road and the 

Ferndale-Kickerville Road SO2 monitors 

were sited for the specific purpose of 

measuring building downwash impacts 

from the Intalco facility.21 With the 

closure of the Intalco facility, these 

monitors would not be considered to be 

sited in the area of maximum 

concentration if a new SO2 emitting 

source were to locate to the area. 

Therefore, Ecology included in its 

maintenance plan a stepwise analytical 

process for deploying SO2 monitors in 

the maintenance area and verifying 

continued attainment. Ecology’s 

intentions with this process are twofold: 

(1) provide an alternative to maintaining 

the existing microscale monitors for the 

duration of the maintenance period and 

(2) providing a basis for potential future 

discontinuation of the two microscale 

Ferndale monitors under 40 CFR 

58.14(c)(3). Note, EPA is not proposing 

in this action to approve any 

discontinuation of any monitoring sites. 

Any future discontinuation of 

monitoring is subject to the approval 

procedures in 40 CFR part 58. 

Ecology lays out its plan for deploying 

monitors and verifying continued 

attainment in Chapter 6 Verification of 

Attainment, Control Measures, and 

Maintenance Demonstration of the 

maintenance plan. This plan builds 

upon Washington’s SIP-approved minor 

and major NSR programs. Washington’s 

SIP includes NWCAA Rule 300 which 

establishes the minor NSR program 

applicable to sources constructed or 

modified in the Ferndale Area. Under 

Rule 300, save for certain limited 

exemptions, sources with a potential to 

emit more than 2.0 tons per year (tpy) 

of SO2 must obtain approval prior to 

construction.22 NWCAA may not 

approve construction or modification 

unless, among other things, the source 

will employ best available control 

technology and allowable emissions 

will not cause or contribute to a 

violation of any NAAQS.23 As to the 

latter, NWCAA may require modeling 

using EPA guidelines in appendix W of 

40 CFR part 51 to determine whether 

construction and operation of the source 

will cause or contribute to a violation of 

any NAAQS. 

Washington’s SIP also includes a 

major new source review program to 

regulate the construction and 

modification of major sources 

constructed or modified in the Ferndale 

Area.24 In general, Washington’s major 

NSR program incorporates by reference 

the Federal major NSR program at 40 

CFR 52.21. The major NSR program 

applies to sources with a potential to 

emit 100 tpy of any regulated NSR 

pollutant for certain listed source 

categories, and 250 tpy of any regulated 

NSR pollutant for unlisted sources. 

Regulated NSR pollutant includes 

pollutants for which the EPA has 

established a NAAQS. 

Similar to the minor NSR program, all 

sources subject to the major NSR 

program must obtain a permit before 

commencing construction. In order to 

obtain a permit, the source must, among 

other things, demonstrate the source 

will apply best available control 

technologies for each regulated NSR 

pollutant that the source has the 

potential to emit in significant amounts. 

In the case of SO2, the significant 

emissions rate is 40 tpy. In addition, the 

source must demonstrate through 

dispersion modeling that construction 

and operation of the source will not 

cause or contribute to a violation of any 

NAAQS or violate any prevention of 

significant deterioration increment. 

In addition to the preexisting NSR 

programs, Washington’s maintenance 

plan includes a stepwise process for 

assessing the cumulative impacts of new 

sources constructed in the area and 

triggering deployment of SO2 monitors. 

This process will ensure that 

cumulative impacts remain below the 

NAAQS should multiple facilities move 

to the nonattainment area. Under the 

maintenance plan verification of 

continued attainment provisions, 

Washington, with NWCAA as the lead 

agency for the jurisdiction in 

coordination with Ecology, will evaluate 

the cumulative impacts of the new 

source or modifications using three 

sequential ‘‘Action Levels.’’ Under 

Action Level 1, Washington will 

conduct cumulative dispersion 

modeling using potential emissions if 

two conditions are met: (1) the 

cumulative potential SO2 emissions in 

the area are greater than or equal to 250 

tons per year of SO2 and (2) the 

proposed new source or modification 

has the potential to emit 40 tons per 

year of SO2 (the significant emission 

rate under the major NSR program). 

Washington will use EPA’s preferred 

screening and dispersion modeling tools 

identified in 40 CFR part 51 appendix 

W (‘‘Appendix W’’) as normally 

applicable for any source seeking a 

construction permit under the NSR 

program. If the results of the modeling 

under Action Level 1 indicate a design 

concentration of greater than or equal to 

90% of the 1-hour NAAQS, then 

Washington will proceed to Action 

Level 2. 

Under Action Level 2, Washington 

will conduct refined dispersion 

modeling that uses actual emissions 

from existing sources and potential 

emissions from the new source or 

modification. If the results of that 

modeling indicate a design 

concentration of greater than or equal to 

50% of the 1-hour SO2 NAAQS, then 

Washington will proceed to Action 

Level 3. 

Under Action Level 3, Washington 

will deploy SO2 ambient monitors 

within 1 year of the initial startup of the 

new source or modification. Any new 

monitors established for verification of 

continued attainment will be operated 

as State and Local Air Monitoring 

Stations (SLAMS) as part of Ecology’s 

Primary Quality Assurance Organization 

(PQAO). Ecology will verify that 

monitor siting complies with 40 CFR 

part 58 appendix E (Probe and 

Monitoring Path Siting Criteria for 

Ambient Air Quality Monitoring) and 

will include any new site proposals in 

its annual Ambient Air Monitoring 

Network Plan. This plan is available for 

public inspection and comment for at 

least 30 days before its submission to 

the EPA by July 1 of each year. Any 

such proposal will be subject to review 

and approval by the EPA Regional 

Administrator, following the process 

described in 40 CFR 58.10. 

The State of Washington has the legal 

authority to enforce and implement the 

maintenance plan for the Whatcom 

County (partial) 2010 SO2 NAA. This 

includes the authority to conduct the 

stepwise ambient air quality analysis, 

deploy monitors, and adopt, implement, 

and enforce any subsequent emissions 

control contingency measures 


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25The EPA last determined that Washington’s SIP 

was sufficient to meet the requirements of 

110(a)(2)(E)(i) of the CAA on February 18, 2021 (86 

FR 10022). 

26See 202_Intalco Sulfur Dioxide Attainment 

Plan_2202035.pdf, at page 45, included in the 

docket for this action. 

determined to be necessary to correct 

future SO2 attainment problems.25

Washington’s SIP-approved NSR 

programs coupled with the stepwise 

approach for assessing cumulative 

impacts is adequate to verify continued 

maintenance of the SO2 NAAQS. The 

250 tpy inventory threshold and 40 tpy 

PTE threshold in Action Level 1 are set 

at emission levels the EPA anticipates 

would not cause or contribute to a 

violation of the NAAQS. For 

comparison, the emissions inventory in 

2017 when the area exceeded the 

NAAQS was 3,987 tpy of emissions 

from the Intalco facility.26 Refining the 

modeling to take into consideration 

actual emissions of existing sources is 

also sufficiently protective, particularly 

considering that Washington will 

deploy monitors if the design 

concentration from this modeling is 

greater than or equal to 50% of the SO2

NAAQS. For these reasons, the EPA is 

proposing to find that Washington’s 

maintenance plan meets the Monitoring 

and ‘‘Verification of Continued 

Attainment’’ requirements. 

e. Contingency Measures in the 

Maintenance Plan 

Section 175A of the CAA requires that 

a maintenance plan include such 

contingency measures as the EPA deems 

necessary to assure that the state will 

promptly correct a violation of the 

NAAQS that occurs after redesignation. 

The maintenance plan should identify 

the contingency measures to be adopted, 

a schedule and procedure for adoption 

and implementation, and a time limit 

for action by the state. A state should 

also identify specific indicators to be 

used to determine when the 

contingency measures need to be 

implemented. The maintenance plan 

must also include a requirement that a 

state will implement all measures with 

respect to control of the pollutant that 

were contained in the SIP before 

redesignation of the area to attainment 

in accordance with section 175A(d). 

The maintenance plan includes an 

action level to determine when the 

contingency plan process is triggered 

and a process of developing and 

implementing appropriate control 

measures. If an SO2 monitor records a 

consecutive two-year average of the 

annual 99th percentile of 1-hour daily 

maximum SO2 values exceeding 67.5 

ppb (90 percent of the NAAQS), and 

such data is certified as accurate, the 

action level is triggered. If the action 

level is triggered, NWCAA will first 

evaluate whether elevated SO2 readings 

are due to exceptional events, as defined 

at 40 CFR 50.1(j), and follow the EPA’s 

exceptional events policy. If the action 

level is triggered and is not found to be 

due to an exceptional event, NWCAA 

will determine if the exceedance was a 

result of a stationary source’s noncompliance with existing regulations 

and/or permit conditions. If so, NWCAA 

will undertake enforcement actions in 

accordance with current agency policy 

and guidance related to compliance and 

enforcement. If the high levels of SO2

are not found to be due to a stationary 

source’s non-compliance, NWCAA will 

work with the entity or entities believed 

to be responsible for the high levels of 

SO2 to evaluate control measures 

necessary to ensure future attainment of 

the NAAQS. The implementation of the 

control measures will take place no later 

than 18 months after NWCAA decides, 

based on quality-assured ambient data, 

that the action-level response described 

above was triggered (a consecutive twoyear average of the annual 99th 

percentile of 1-hour daily maximum 

SO2 values exceeding 67.5 ppb). 

Washington must submit to the EPA 

its analysis demonstrating that the 

proposed control measures are adequate 

to ensure continued maintenance of the 

2010 1-hour SO2 NAAQS in the area or 

to return the area to attainment of the 

NAAQS. Since the only significant 

source of SO2 in the nonattainment area 

has shut down, it is not possible to 

develop specific contingency measures 

until the cause of the elevated 

concentrations is known. The EPA is 

proposing to find that Washington’s 

maintenance plan meets the 

‘‘Contingency Measures’’ requirement. 

The EPA has concluded that the 

maintenance plan adequately addresses 

the five basic components of a 

maintenance plan: The attainment 

emissions inventory, maintenance 

demonstration, monitoring, verification 

of continued attainment, and a 

contingency plan. Therefore, the EPA 

proposes to find that the maintenance 

plan SIP revision submitted by 

Washington for the Whatcom County 

(partial) 2010 SO2 NAA meets the 

requirements of section 175A of the 

CAA and is approvable. 

IV. What are the actions the EPA is 

proposing to take? 

The EPA is proposing to take the 

following four separate but related 

actions: (1) determine that the Whatcom 

County (partial) SO2 nonattainment area 

is attaining the 2010 1-hour SO2

NAAQS; (2) approve Washington’s plan 

for maintaining the 2010 1-hour SO2

NAAQS (maintenance plan), including 

proposed approval of a ‘‘reproducible 

approach’’ to representing the air 

quality of the affected area in the event 

that the monitors that were sited for the 

Intalco facility shut down; (3) 

redesignate the Whatcom County 

(partial) SO2 nonattainment area to 

attainment for the 2010 1-hour SO2

NAAQS; and (4) determine that the 

Whatcom County (partial) SO2 NAA has 

clean monitoring data. Section III of this 

document provides a discussion of each 

of these proposed actions. 

The EPA is also proposing to approve 

the maintenance plan under the 2010 

NAAQS for the Whatcom County 

(partial) SO2 nonattainment area into 

the Washington SIP (under CAA section 

175A). The maintenance plan 

demonstrates that the area will continue 

to maintain the 2010 1-hour SO2

NAAQS and includes a process to 

develop contingency measures to 

remedy any future violations of the 2010 

1-hour SO2 NAAQS and procedures for 

evaluation of potential violations. 

Additionally, the EPA is proposing to 

determine that the Whatcom County 

(partial) SO2 nonattainment area has 

met the criteria under CAA section 

107(d)(3)(E) for redesignation from 

nonattainment to attainment for the 

2010 1-hour SO2 NAAQS. On this basis, 

the EPA is proposing to approve 

Washington’s redesignation request for 

the area. Final approval of Washington’s 

redesignation request would change the 

legal designation of the portion of 

Whatcom County designated 

nonattainment at 40 CFR 81.348 to 

attainment for the 2010 1-hour SO2

NAAQS. 

The EPA is also proposing to 

determine that the Whatcom County 

(partial) SO2 nonattainment area has 

attaining monitoring data for the 2010 

SO2 primary NAAQS based on the most 

recent complete three-year period 

(2021–2023) design value period that 

meets the clean data policy. As noted 

elsewhere, in the event that EPA does 

not finalize the proposed redesignation, 

the EPA may choose to finalize the 

clean data determination, thereby 

suspending the attainment planning 

related requirements for the area. 

V. Statutory and Executive Order 

Reviews 

Under the CAA, redesignation of an 

area to attainment is an action that 

affects the status of a geographical area 

and does not impose any additional 

regulatory requirements on sources 

beyond those imposed by state law. A 

redesignation to attainment does not in 


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and of itself create any new 

requirements, but rather results in the 

applicability of requirements contained 

in the CAA for areas that have been 

redesignated to attainment. In addition, 

the Administrator is required to approve 

a SIP submission that complies with the 

provisions of the Clean Air Act and 

applicable Federal regulations. 42 

U.S.C. 7410(k); 40 CFR 52.02(a). Thus, 

in reviewing SIP submissions, the EPA’s 

role is to approve state choices, 

provided that they meet the criteria of 

the Clean Air Act. Accordingly, this 

action merely proposes to approve state 

law as meeting Federal requirements 

and does not impose additional 

requirements beyond those imposed by 

state law. For these reasons, 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 14094 (88 FR 

21879, April 11, 2023); 

• 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 subject to Executive Order 

13045 (62 FR 19885, April 23, 1997) 

because it approves a state program; 

• 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, this proposed action, 

pertaining to redesignation of the 

Whatcom County (partial) SO2

nonattainment area and approval of a 

maintenance plan for the area, would 

not be approved to apply on any Indian 

reservation land or in any other area 

where the EPA or an Indian Tribe has 

demonstrated that a Tribe has 

jurisdiction. In those areas of Indian 

country, the rule would not have Tribal 

implications and would not impose 

substantial direct costs on tribal 

governments or preempt Tribal law as 

specified by Executive Order 13175 (65 

FR 67249, November 9, 2000). 

Consistent with EPA policy, the EPA 

provided a consultation opportunity to 

Tribes located near the nonattainment 

area, in letters dated July 25, 2024 and 

July 29, 2024, included in the docket for 

this action. 

Executive Order 12898 (Federal 

Actions to Address Environmental 

Justice in Minority Populations and 

Low-Income Populations, 59 FR 7629, 

February 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. The 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.’’ The 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.’’ 

The Washington Department of 

Ecology did evaluate environmental 

justice considerations as part of its SIP 

submittal; the CAA and applicable 

implementing regulations neither 

prohibit nor require such an evaluation. 

The EPA did not perform an EJ analysis 

and did not consider EJ in this action. 

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 Executive Order 

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, Intergovernmental relations, 

Ozone, Particulate matter, Reporting 

and recordkeeping requirements, Sulfur 

oxides, Volatile organic compounds. 

Authority: 42 U.S.C. 7401 et seq. 

Dated: September 19, 2024. 

Casey Sixkiller, 

Regional Administrator, Region 10. 

[FR Doc. 2024–22171 Filed 9–26–24; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 721 

[EPA–HQ–OPPT–2021–0221; FRL–12141– 

01–OCSPP] 

RIN 2070–AB27 

Significant New Use Rules on Certain 

Chemical Substances (21–3.F) 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: EPA is proposing significant 

new use rules (SNURs) under the Toxic 

Substances Control Act (TSCA) for 

chemical substances that were the 

subject of premanufacture notices 

(PMNs). The chemical substances 

received ‘‘not likely to present an 

unreasonable risk’’ determinations 

pursuant to TSCA. The SNURs require 

persons who intend to manufacture 

(defined by statute to include import) or 

process any of these chemical 

substances for an activity that is 

proposed as a significant new use by 

this rulemaking to notify EPA at least 90 

days before commencing that activity. 

The required notification initiates EPA’s 

evaluation of the conditions of use for 

that chemical substance. In addition, the 

manufacture or processing for the 

significant new use may not commence 

until EPA has conducted a review of the 

required notification, made an 

appropriate determination regarding 

that notification, and taken such actions 

as required by that determination. 

DATES: Comments must be received on 

or before October 28, 2024. 

ADDRESSES: Submit your comments, 

identified by docket identification (ID) 

number EPA–HQ–OPPT–2021–0221, at 

https://www.regulations.gov. Follow the 

online instructions for submitting 

comments. Do not submit electronically 

any information you consider to be 

Confidential Business Information (CBI) 

or other information whose disclosure is 

restricted by statute. Additional 

instructions on commenting and visiting 

the docket, along with more information 

about dockets generally, is available at 

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

FOR FURTHER INFORMATION CONTACT: 

For technical information: William 

Wysong, New Chemicals Division 

(7405M), Office of Pollution Prevention 

and Toxics, Environmental Protection 

Agency, 1200 Pennsylvania Ave. NW, 

Washington, DC 20460–0001; telephone 

number: (202) 564–4163; email address: 

wysong.william@epa.gov. 

For general information: The TSCAHotline, ABVI-Goodwill, 422 South 


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