Allcast owns and operates a secondary aluminum production facility at 217 Weis Street in Allenton, Wisconsin. Allcast operates three furnaces used for melting aluminum. Between March 2003 and September 2004, Allcast melted coated aluminum customer return materials in its furnaces. Allcast's Allenton facility was subject to the requirements at 40 C.F.R. Part 63 during the time that it melted painted/coated customer returns. Allcast is an area source for Hazardous Air Pollutants (HAP).