SUPPLEMENTARY INFORMATION:

Throughout this document, “we,” “us,” and “our” refer to the EPA. We use multiple abbreviations and terms in this proposed rule. While this list may not be exhaustive, for ease of reading and for reference purposes, the EPA defines the following terms and acronyms here:

ADEQ—Arizona Department of Environmental Quality

BACM—best available control measures

CAA—Clean Air Act

CBI—confidential business information

CFR—Code of Federal Regulations

EPA—Environmental Protection Agency

IBR—incorporation by reference

MSM—most stringent measures

NAAQS—national ambient air quality standards

PCAQCD—Pinal County Air Quality Control District

PM—particulate matter

PM₁₀ —particulate matter 10 micrometers or smaller in diameter

RACT—reasonably available control technology

RACM—reasonably available control measures

SIP—State Implementation Plan

TFV—threshold friction velocity

TSD—technical support document

Table of Contents

I. Executive Summary

A. What action is the EPA taking?

B. What is the legal authority and what are the requirements?

II. Background

A. PM₁₀ NAAQS

B. Area Description

III. Summary of Arizona's Submittal

A. What did Arizona submit?

B. Are there other related submittals or actions?

IV. The EPA's Evaluation of Arizona's Submittal

A. How is the EPA evaluating the submittal?

B. Does the submittal meet the evaluation criteria?

C. Proposed Action and Public Comment

V. Incorporation by Reference

VI. Statutory and Executive Order Reviews

I. Executive Summary

A. What action is the EPA taking?

The EPA is proposing to approve a February 13, 2023 SIP submittal from Arizona that includes amendments to fugitive dust rules and related test methods for the West Pinal County portion of the Arizona SIP. Table 1 lists the new or amended rules from the submittal that we are proposing to approve from the PCAQCD Code of Regulations.

These revisions were submitted to support Arizona's attainment plan for the West Pinal County PM₁₀ nonattainment area, including to meet requirements for Best Available Control Measures (BACM) and Most Stringent Measures (MSM). The rules from PCAQCD, Code of Regulations, Chapter 4, Article 1, Sections 4-1-010, 4-1-015, 4-1-020, 4-1-030, 4-1-040, 4-1-045, 4-1-050, and 4-1-060, “West Pinal PM₁₀ Serious NAA Fugitive Dust,” (“Article 1”) regulate PM and PM₁₀ emissions from “non-traditional” sources of fugitive dust: open areas/vacant lots, vehicle use in open areas/vacant lots, weed abatement, unpaved lots, unpaved roads, and paved public roadways. The rules from PCAQCD, Code of Regulations Chapter 4, Article 3, Sections 4-3-160, 4-3-170, and 4-3-180 “Construction Sites—Fugitive Dust,” (“Article 3”) regulate PM and PM₁₀ emissions from dust generating activities performed at construction sites. Finally, the rule from PCAQCD, Code of Regulations Chapter 4, Article 9, Section 4-9-310 “Test Methods,” (“Article 9”) establishes test methods that are relied upon by Articles 1 and 3 for determining compliance with rule requirements. Additionally, we are proposing to approve the rescission of PCAQCD, Code of Regulations, Chapter 4, Article 3, Section 4-3-190, “Violations,” adopted October 28, 2015, (“Section 4-1-190”) from the SIP.

If finalized as proposed, the rules listed in Table 1 of this document will be incorporated into the federally enforceable portion of the Arizona SIP and Section 4-3-190 will be removed from the Arizona SIP. ( printed page 66045)

B. What is the legal authority and what are the requirements?

We are proposing this action under section 110 of the CAA. Pursuant to CAA section 110(a), States are required to submit SIPs to the EPA that provide for the implementation, maintenance, and enforcement of the national ambient air quality standards (NAAQS). CAA section 110(k) requires SIPs to meet certain procedural requirements and requires the EPA to approve or disapprove SIP submissions. CAA section 110(l) requires States to provide public notice and an opportunity for public hearing of SIP revisions prior to their submittal and prohibits the EPA from approving any SIP revisions that would interfere with attainment or maintenance of a NAAQS, reasonable further progress, or other applicable requirements of the CAA. If a SIP submittal meets all the applicable CAA requirements, then the EPA must approve the submittal under CAA section 110(k)(3).

For this submittal to be approved, we must consider CAA requirements related to the emissions limitations in the submitted rules. CAA sections 110(a)(2)(A) and 302(k) require emissions limitations in the SIP to be enforceable and continuous, respectively. CAA section 172(c)(6) requires SIPs for nonattainment areas “include enforceable emissions limitations, and such other control measures means or techniques . . . as well as schedules and timetables for compliance, as may be necessary or appropriate to provide for attainment of such standard in such area by the applicable attainment date . . . .” Also, 40 CFR part 51, subpart K, requires SIPs to contain legally enforceable procedures for monitoring the status of compliance with the requirements in the control strategy. Finally, while these rules were submitted to meet BACM requirements under CAA section 189(b)(1)(B) and MSM requirements under CAA section 188(e), we are not evaluating them for BACM or MSM in this rulemaking action. We will evaluate BACM and MSM in a separate Federal Register notice in the context of the broader attainment plan action for the West Pinal County PM₁₀ nonattainment area.

We are proposing that this submittal meets all applicable CAA requirements and are proposing to fully approve it under CAA section 110(k)(3).

II. Background

A. PM₁₀ NAAQS

The EPA establishes the NAAQS for certain ambient air pollutants at levels required to protect public health and welfare. Emissions of PM₁₀ contribute to effects that are harmful to human health and the environment, including premature mortality, aggravation of respiratory and cardiovascular disease, decreased lung function, visibility impairment, and damage to vegetation and ecosystems. Accordingly, the EPA revised the NAAQS for particulate matter on July 1, 1987, replacing the standards for total suspended particulates, which are particles 30 micrometers or smaller in diameter, with new standards applying only to PM₁₀ .^[1] In revising the NAAQS for particulate matter, we established a 24-hour standard of 150 micrograms per cubic meter (µg/m^[3] ), as well as an annual standard that was subsequently revoked in 2006.^[2]

B. Area Description

On May 31, 2012, the EPA designated a portion of state lands in western Pinal County, Arizona, as nonattainment for the 1987 p.m.₁₀ NAAQS.^[3] The West Pinal County PM₁₀ nonattainment area encompasses approximately 1,325 square miles lying within a basin characterized by low desert valleys between the Phoenix and Tucson metropolitan areas. It includes all or portions of the incorporated cities and towns of Apache Junction, Casa Grande, Coolidge, Eloy, Florence, Queen Creek, and Maricopa, with a population of approximately 343,788 based upon July 1, 2017 U.S. Census Bureau data. Average elevation in the nonattainment area is 1,403 feet above sea level, with elevations of up to 6,441 feet directly east of the nonattainment area, which becomes more mountainous.

The West Pinal County PM₁₀ nonattainment area was originally classified as “Moderate” nonattainment on May 31, 2012, with an attainment date of December 31, 2018. CAA section 188(b)(2) requires the EPA to determine whether a PM₁₀ nonattainment area classified as Moderate has attained the 1987 24-hour PM₁₀ NAAQS by the area's attainment date. If the EPA determines that a Moderate area has not attained the NAAQS by the relevant attainment date, then the area shall be reclassified as a Serious area by operation of law. On June 24, 2020, we took final action to determine that the West Pinal County PM₁₀ nonattainment area did not attain the 1987 24-hour PM₁₀ NAAQS, and as a result, it was reclassified to Serious nonattainment by operation of law.^[4]

III. Summary of Arizona's Submittal

A. What did Arizona submit?

On February 13, 2023, the Arizona Department of Environmental Quality (ADEQ) submitted amended rules from PCAQCD to the EPA for approval into the West Pinal County portion of the Arizona SIP. The rule amendments were adopted by PCAQCD on January 25, 2023, and submitted to support Arizona's attainment plan for the West Pinal County PM₁₀ nonattainment area. Table 1 of this document lists the adopted and/or amended rules that were submitted and that we are proposing to approve into the SIP. The submittal also requests to rescind Section 4-3-190, which was repealed by the Pinal County Board of Supervisors on January 25, 2023.^[5] Additionally, the submittal requests that we approve Section 4-3-320, “Test Methods for Stabilization for Unpaved Roads and Unpaved Parking Lots,” adopted on June 3, 2009, (“Section 4-3-320”) and 4-3-340, “Visual Opacity Test Methods,” adopted on June 3, 2009, (“Section 4-3-340”). On August 13, 2023, this submittal was deemed by operation of law to be complete. We have reviewed the submittal to ensure it meets the completeness criteria in 40 CFR part 51, appendix V.

B. Are there other related submittals or actions?

We approved earlier versions of the rules in Article 1 and Article 3 into the SIP in 2017.^[6] If we finalize this rulemaking as proposed, then the January 25, 2023 versions of the rules from Article 1 and Article 3, as listed in Table 1 of this document, will replace the previously approved versions in the SIP.

Regarding test methods from Article 9, Section 4-9-310, “Test Methods for Stabilization for Unpaved Shoulders and Medians of Paved Roads,” adopted on January 25, 2023, (“Section 4-9-310”) has not been previously approved into the SIP. However, in 2010, we previously approved the currently submitted versions of Sections 4-9-320 and 4-9-340.^[7] That is, Sections 4-9-320 and 4-9-340 are already approved into the SIP, and no further action from the EPA is needed related to the current ( printed page 66046) request to approve them into the SIP. PCAQCD has not amended these rules locally.

Finally, PCAQCD repealed Section 4-3-190 that we previously approved into the SIP in 2017.^[8]

IV. The EPA's Evaluation of Arizona's Submittal

A. How is the EPA evaluating the submittal?

Emission limitations in the SIP must be enforceable, continuous, and must not interfere with applicable requirements concerning attainment and reasonable further progress or other CAA requirements.^[9] Additionally, 40 CFR part 51, subpart K, requires SIPs to have enforceable procedures for monitoring the status of compliance with the requirements in the control strategy.

The PCAQCD regulates a PM₁₀ nonattainment area classified as Serious for the 1987 24-hour PM₁₀ NAAQS. In Serious nonattainment areas, SIPs must implement BACM, including Best Available Control Technology.^[10] In addition, because Arizona is seeking a five-year extension of the attainment date, the SIP must also implement MSM.^[11] These evaluations are included in the context of the broader attainment plan rulemaking and are not included in this rulemaking. In this rulemaking, we are evaluating these rules for approval into the SIP under CAA section 110 requirements.

Our evaluation also relies on relevant guidance and policy documents to evaluate enforceability and revisions/relaxation requirements.^[12]

B. Do the submittals meet the evaluation criteria?

We evaluated these rules to ensure they meet CAA requirements and are consistent with relevant guidance regarding enforceability and SIP revisions.

1. Article 1 Rules

Article 1 applies to “non-traditional” fugitive dusts sources in the West Pinal County PM₁₀ nonattainment area: open areas/vacant lots, vehicle use in open areas/vacant lots, unpaved lots, weed abatement and/or trash removal, unpaved roads, and paved public roadways. Affected owners and operators are required to implement control measures that will meet visible emission and surface stabilization standards. Compliance with stabilization and visible emission standards are determined through applicable test methods in Article 9.

Each of the regulated activities has specific standards and control measures that must be met. For visible emission standards, either a 20 percent opacity limit applies or visible emissions, including fugitive dust, are prohibited from going beyond the property line. Owners and operators choose the stabilization standard they will meet from a list of options, such as maintaining a soil crust, meeting a minimum threshold friction velocity (TFV) ^[13] limit, covering the area with a certain percentage of vegetative cover, or meeting silt loading ^[14] limits. Owners and operators then choose a control measure to implement for each regulated activity from a menu of options, such as establishing vegetative cover, applying dust suppressants, applying water, restoring the area to an undisturbed native condition, establishing barriers to prevent unauthorized vehicle access, paving parking lots, and applying and maintaining surface gravel. Additionally, disturbed surface areas of 0.10 acres (4,356 square feet) or greater must sign up to receive the Pinal County Dust Control Forecast and ensure control measures are implemented on the day prior and day of a high dust risk forecast.

Article 1 includes a new standard for paving existing unpaved roadways. Beginning January 1, 2024, each city, county, or state agency with primary responsibility for any existing unpaved road within the West Pinal County PM₁₀ nonattainment area was required to annually pave an average of 20 percent of unpaved roads within the agency's jurisdiction.^[15] Further, if the EPA determines the West Pinal County PM₁₀ nonattainment area failed to make reasonable further progress, or to attain the PM₁₀ NAAQS by the attainment date, the rules include a contingency measure where any public unpaved road with average daily trips of 26 or more will have a speed limit of 15 miles per hour.

For paved public roads, Article 1 establishes new standards by requiring street sweeping to be done by certified street sweepers and establishing paved road development standards that specify minimum surface stabilization standards for road shoulders.

Each person subject to Article 1 is required to compile and retain records that provide evidence of control measure application ( i.e., receipts and/or purchase records). The records must describe the type of treatment or control measure, extent of coverage, and date applied. Records must be available to the District upon request and maintained for at least two years. Agencies subject to the road paving requirement must submit annual progress reports by January 30 of each year related to the annual road paving requirements and the number of paved roads with unpaved shoulders.

Overall, the visible emission limits, stabilization standards, and control measures are tailored to minimizing fugitive dust from each type of regulated activity, result in continuous emissions limitations, and the associated recordkeeping and reporting requirements are sufficient to meet the enforceability requirements of CAA sections 110(a)(2)(A) and 172(c)(6) and 40 CFR part 51, subpart K. The amendments strengthen the existing SIP, consistent with CAA section 110(l), by expanding existing control measures, such as lowering applicability thresholds, adding or revising visible emission standards, establishing clear timelines for when control measures must be implemented, clarifying that control measures are considered to be implemented when the associated visible emission and/or stabilization standards are met, and adding new control measures for paved and unpaved roads. Because they meet all applicable CAA requirements, we propose approving the rules from Article 1 into the Arizona SIP.

2. Article 3 Rules

Article 3 applies to fugitive dusts sources at construction sites within the ( printed page 66047) West Pinal County PM₁₀ nonattainment area. Affected owners and operators are required to implement control measures and meet visible emission standards and surface stabilization standards for dust generating activities. Additionally, owners or operators are required to obtain a dust permit when dust-generating operations at construction sites disturb a total surface area of 0.10 acres (4,356 square feet) or more. All permit applications must contain a dust control plan that identifies all control measures to be implemented before, after, and while conducting any dust-generating operation.

Sites with a dust control permit must: for each project of 5 or more acres, have a project information sign that identifies how the public can file a dust complaint to the District; meet dust control training requirements once every three years from the District; except in certain high wind conditions, implement all control measures necessary to maintain soil stability; implement control measures specified for each type of activity, such as active areas, demolition, weed abatement, trackout, site grade preparation, trenching, and haul roads; limit dust generated on the property to 20 percent opacity, and ensure no visible emissions, including fugitive dust, go beyond the property line; install no trespassing signs for project sites when activities cease for 30 or more days at a time; and, on a high dust risk day, continue to implement control measures that maintain compliance with the applicable standards or cease dust-generating activities and ensure disturbed surface areas are stablized for the day. Construction sites that do not require a dust control permit are subject to the same general control measures, visible emission standards, and stabilization requirements but are not subject to signage and dust control training requirements. Similar to Article 1, owners and operators subject to Article 3 choose from a menu of options to meet control measure requirements and surface stabilization standards.

Any person who conducts dust-generating operations that require a dust control permit is required to keep written records of self-inspection on each day dust-generating operations are conducted. Self-inspection records include daily inspections for crusted or damp soil, trackout conditions and clean-up measures, daily water usage for dust control measures, and dust suppressant application. Any person who conducts dust-generating operations that do not require a dust control permit must maintain records that provide evidence of control measure application, by indicating the type of treatment or control measure, extent of coverage, and date applied. Records are required to be maintained for two years, except for construction sites at a facility with a title V operating permit, which must maintain records for five years.

Overall, the dust control permit requirements, visible emission limits, stabilization standards, and control measures are tailored to minimizing fugitive dust for each type of regulated activity, result in continuous emission limitations, and associated recordkeeping requirements are sufficient to meet the enforceability requirements of CAA sections 110(a)(2)(A) and 172(c)(6) and 40 CFR part 51, subpart K. The amendments would strengthen the existing SIP in several ways, consistent with CAA section 110(l), including adding a visible emission standard that prohibits visible emissions from going beyond the property line, adding signage requirements and dust control operator training requirements, specifying the threshold for obtaining a dust control permit, specifying the dust generating activities that are required to implement control measures, specifying the types of control measures that apply to each type of dust generating activity, specifying that control measures must be implemented at all times, and requiring daily records of actions to reduce fugitive dust. Because they meet all applicable CAA requirements, we are proposing to approve the rules from Article 3 into the Arizona SIP.

3. Rescission of Section 4-3-190

Previously, if certain conditions were met, Section 4-3-190 provided an exemption from the requirements of Article 3 during high wind conditions and emergency maintenance of flood control channels and water retention basins. The rule amendments adopted by the District to Article 3 on January 25, 2023, incorporate requirements that apply during these circumstances within other provisions of Article 3 such that removal of this section would not relax any existing SIP requirement and is consistent with CAA section 110(l).^[16] Therefore, we are proposing to approve this rescission request.

4. Article 9 Rules

Section 4-9-310 establishes test methods to determine whether unpaved shoulders and medians of paved roads meet applicable surface stabilization standards. It includes an opacity test method, silt loading test method, and gravel depth and silt content test method. These test methods are used to determine compliance with stabilization standards in Article 1 and 3.

Based upon our evaluation, these test methods are enforceable and consistent with comparable test methods established in Federal requirements and SIP-approved fugitive dust rules in other States. We consider their use with Articles 1 and 3 to be an appropriate application of the test methods. The test methods ensure the associated emission limits will meet the enforceability requirements of CAA sections 110(a)(2)(A) and 172(c)(6) and 40 CFR part 51, subpart K, strengthen the SIP, and would not interfere with any other CAA requirements, consistent with CAA section 110(l). Because the rule meets all applicable CAA requirements, we are proposing to approve Section 4-9-310 into the Arizona SIP.

As stated above in section III.B, the EPA is not acting on Sections 4-9-320 and 4-9-340 from the state's submittal in this action. These rules are already approved into the SIP and PCAQCD has not amended them locally, so no further action is needed.

5. Conclusions

Based on our review, the rules proposed for approval, as listed in Table 1 of this document, and the proposed rescission of Section 4-3-190 meet the relevant CAA requirements. The technical support documents (TSDs) for each article (Articles 1, 3, and 9) have more information on our evaluation and are available in the docket for this rulemaking.

C. Proposed Action and Public Comment

As authorized in section 110(k)(3) of the Act, the EPA proposes to approve Arizona's February 13, 2023 SIP submittal, including approving the rules listed in Table 1 of this document into the Pinal County portion of the Arizona SIP and the rescission of Section 4-3-190 from the SIP, because they fulfill all relevant requirements. We will accept comments from the public on this proposal until November 18, 2026. If finalized as proposed, our final action will incorporate the rules listed in Table 1 of this document into the federally enforceable SIP and Section 4-3-190 will be removed from the SIP. ( printed page 66048)

V. Incorporation by Reference

In this document, the EPA is proposing to include in a final EPA rule regulatory text that includes incorporation by reference. In accordance with requirements of 1 CFR 51.5, the EPA is proposing to incorporate by reference PCAQD, Code of Regulations, Chapter 4, Article 1, Sections 4-1-010, “General Applicability;” 4-1-015, “Exemptions;” 4-1-020, “Definitions;” 4-1-030, “Standards;” 4-1-040, “Recordkeeping;” 4-1-045, “Reporting Requirements;” 4-1-050, “Records Retention;” and 4-1-060, “Violations;” as amended on January 25, 2023, which regulate fugitive dust emissions from open areas/vacant lots, unpaved lots, weed abatement, unpaved roads, and paved public roadways in the West Pinal County Serious PM₁₀ Nonattainment Area. The EPA is also proposing to incorporate by reference PCAQD, Code of Regulations, Chapter 4, Article 3, Sections 4-3-160, “General Provisions—West Pinal PM₁₀ Nonattainment Area;” 4-3-170, “Definitions;” and 4-3-180 “Dust Generating Operations: Standards, Application, Permit, Recordkeeping and Training Requirements” as amended on January 25, 2023, which regulate fugitive dust emissions from construction sites in the West Pinal County Serious PM₁₀ Nonattainment Area. The EPA is also proposing to incorporate by reference PCAQD, Code of Regulations, Chapter 4, Article 9, Section 4-9-310, “Test Methods for Stabilization for Unpaved Shoulders and Medians of Paved Roads,” as adopted on January 25, 2023, which establishes test methods used to determine compliance with requirements for dust generating activities contained in PCAQD, Code of Regulations, Chapter 4, Articles 1 and 3. The EPA has made, and will continue to make, these materials available through www.regulations.gov and at the EPA Region IX Office (please contact the person identified in the FOR FURTHER INFORMATION CONTACT section of this preamble for more information).

VI. Statutory and Executive Order Reviews

Under the CAA, the Administrator is required to approve a SIP submission that complies with the provisions of the 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 CAA. Accordingly, this proposed action merely proposes to approve 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 underExecutive Order 12866 (58 FR 51735, October 4, 1993);
• Is not anExecutive Order 14192 (90 FR 9065, February 6, 2025) regulatory action because this action is not significant under Executive Order 12866;
• 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 inExecutive Order 13132 (64 FR 43255, August 10, 1999);
• Is not subject toExecutive Order 13045 (62 FR 19885, April 23, 1997) because it proposes to approve a state program;
• Is not a significant regulatory action subject toExecutive 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 CAA.

In addition, the SIP is not 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 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).

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

91 FR 66043