Air Plan Approval; Arizona; Stationary Sources; New Source Review; Ammonia

The Environmental Protection Agency (EPA) is supplementing its prior proposed approval of regulatory revisions to the Arizona Department of Environmental Quality (ADEQ) portion of the applicable Clean Air Act (CAA or Act) state implementation plan (SIP) for the State of Arizona. This supplemental proposal is primarily intended to make corrections to ADEQ's SIP-approved rules for the issuance of CAA New Source Review (NSR) permits for stationary sources, with a focus on preconstruction permit requirements under the Act for major stationary sources and major modifications of such sources. It proposes conditional approval of ADEQ's NSR submittal specifically with respect to the CAA requirements related to ammonia as a precursor to PM2.5 under the NA-NSR program requirements in CAA section 189(e). We are seeking comment on our proposed action and plan to follow with a final action.