Air Plan Approval; Wisconsin; Site-Specific Sulfur Dioxide Requirements for USG Interiors, LLC

The Environmental Protection Agency (EPA) is approving, under the Clean Air Act (CAA), a State Implementation Plan (SIP) revision submitted by Wisconsin on January 31, 2017, and supplemented on March 20, 2017. This SIP submittal consists of Wisconsin Administrative Order AM-16-01, which imposes a requirement for a taller cupola exhaust stack, a sulfur dioxide (SO2) emission limit in conjunction with a minimum cupola stack flue gas flow rate, and associated requirements on the mineral wool production process at the USG Interiors LLC facility located in Walworth, Wisconsin (USG-Walworth). Wisconsin submitted this SIP revision to enable the area near USG- Walworth to qualify for being designated ``attainment'' of the 2010 primary SO2 National Ambient Air Quality Standards (NAAQS), a matter that will be addressed in a separate future rulemaking. EPA is approving AM-16-01 into the Wisconsin SIP, which makes the AM-16-01 requirements federally enforceable.