In relation to violations at a petroleum refinery in Superior, Wisconsin, settling CAA defendants under the third amendment to a 2011 consent decree must implement two emissions-reduction projects in the Superior, Wisconsin, area in order to fully mitigate the harm caused by excess emissions resulting from a fire and explosion at the refinery on April 26, 2018, and implement several safety-related enhancements to the design, maintenance, and operation of its alkylation process equipment at the refinery.