United Taconite LLC (UTAC) is a taconite iron ore mine and processing plant in Minnesota that produces iron pellets for use in integrated steel mills. The company is operated by Cliffs Natural Resources. The facility's operations include mining, crushing, and pulverizing taconite ores to create a concentrate that is then dried, pelletized into balls, and sent into high-temperature indurating furnaces to harden before being transported to integrated steel mills. UTAC is subject to the National Emissions Standards for Hazardous Air Pollutants: Taconite and Iron Ore Processing, at 40 C.F.R. Part 63, Subpart RRRRR (Taconite MACT). The main pollutant of concern is particulate matter (PM). Region 5 inspectors identified periods of time when UTAC bypassed a primary control device, resulting in exceedances of the Taconite MACT standard for PM. Additionally, UTAC had several violations of its parametric monitoring limits (pressure drop and water flow rate) required to demonstrate compliance with the Taconite MACT limits. The consent decree includes the following injunctive relief: (1) automation of the process by which all the facility?s indurating furnaces are fueled when a stack cap is opened, so that, immediately upon a stack cap beginning to open, the indurating furnace will be fueled exclusively by natural gas; and (2) performance of a root cause failure analysis at the facility's indurating furnace wet scrubber operation during low production operations. The consent decree provi