Within 60 days after October 1, 1975 (the effective date of Public Act 79-794), the Mayor of Decatur, with the advice and consent of the Decatur city council, shall appoint 9 members of the board, 3 members to be appointed for terms of 1 year, 3 members to be appointed for terms of 2 years, and 3 members to be appointed for terms of 3 years, such terms commencing on the date each is appointed. At the expiration of the term of any member, his successor shall be appointed by the Mayor of Decatur in like manner. All successors shall hold office for a term of 3 years from the date of appointment, except in case of an appointment to fill a vacancy.