Workers represented by the Building Trades Unions will return to Marathon Petroleum Corp’s (MPC.N) refinery in Catlettsburg, Kentucky on Monday, even as a strike by the United Steelworkers drags into a second week, documents obtained by Reuters show. The USW began a strike Feb. 1 at nine refineries and chemical plants, including Marathon’s 240,000 barrel-a-day Kentucky plant. Buildings Trades Unions’ workers will not be replacing striking workers’ running the plant, according to the letter.