Promulgation of Air Quality Implementation Plans; Arizona; Regional Haze Federal Implementation Plan; Reconsideration

The Environmental Protection Agency (EPA) is revising portions of the Arizona Regional Haze Federal Implementation Plan (FIP) applicable to the Coronado Generating Station (Coronado) and the Cholla Power Plant (Cholla). In response to a petition for reconsideration from the Salt River Project Agricultural Improvement and Power District (SRP), the owner and operator of Coronado, we are replacing a plant- wide compliance method with a unit-specific compliance method for determining compliance with the best available retrofit technology (BART) emission limits for nitrogen oxides (NO<INF>X</INF>) from Units 1 and 2 at Coronado. While the plant-wide limit for NO<INF>X</INF> emissions from Units 1 and 2 was established as 0.065 lb/MMBtu, we are now setting a unit-specific limit of 0.065 lb/MMBtu for Unit 1 and 0.080 lb/MMBtu for Unit 2. In addition, we are revising the work practice standard in the FIP for Coronado. Finally, we are removing the affirmative defense for malfunctions, which applied to both Coronado and Cholla.