Federal Register #EPA-R09-OAR-2025-3821

EPA Approval of Arizona Hayden SO₂ Attainment Plan (Regulatory Action)

This opportunity concerns the Environmental Protection Agency (EPA) Region 9's final approval of Arizona's Hayden SO₂ Attainment Plan, a regulatory action addressing compliance with national ambient air quality standards for sulfur dioxide. - Government Buyer: - Environmental Protection Agency (EPA), Region 9 - Regulated Entity: - ASARCO LLC (Hayden copper smelter) - Scope of Approval: - Arizona's State Implementation Plan (SIP) revisions for the Hayden SO₂ nonattainment area - Covers both 1971 and 2010 SO₂ NAAQS - Includes attainment demonstration, emissions inventories, control measures (RACM/RACT), new source review, emissions limitations, and contingency measures - Notable Requirements: - EPA approval makes new emissions controls and limits federally enforceable - Addresses Clean Air Act sections 110, 172, 191, and 192 - Responds to public comments on benefit valuation and environmental justice analysis (not required for this rulemaking) - No procurement of products or services; this is a regulatory action - OEMs/Vendors: - ASARCO LLC is the dominant source and regulated entity; no other OEMs or vendors are involved

Description

The Environmental Protection Agency (EPA) is finalizing approval of revisions to the Arizona state implementation plan (SIP) for attaining the 1971 and 2010 sulfur dioxide (SO₂) national ambient air quality standards (NAAQS) in the Hayden SO₂ nonattainment area. These SIP revisions, collectively called the "Hayden SO₂ Plan" or "Plan," include Arizona's attainment demonstration and other elements required under Clean Air Act (CAA) sections 110, 172, 191, and 192. The revisions address requirements for meeting reasonable further progress (RFP), control measures and technology (RACM/RACT), emissions inventories, nonattainment new source review, emissions limitations, and contingency measures. The EPA approves these SIP revisions as meeting CAA requirements.

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