Calumet Specialty Products Partners, L.P. announced that co-founder Fred Fehsenfeld, chairman of the board of The Heritage Group – the general partner of Calumet – will retire effective May 1. On that date, current Calumet CEO Steve Mawer will become executive chairman of the board; Todd Borgmann, currently executive vice president and chief financial officer, will assume the role of CEO; and Vince Donargo, currently chief accounting officer, will assume the role of EVP and CFO.