SPRINGFIELD — The Illinois Department of Corrections is making plans to downsize — plans that a major public employee union claims have not been shared with its members.With inmate population dwindling to 28,000 and mounting maintenance bills on prison buildings at correctional centers across the state, DOC developed a plan which may include significant downsizing at the Vandalia and Pontiac correctional centers.“These facilities are referenced due to current operational needs,” IDOC chief of staff Camile Lindsay said in …