Within 60 days after September 11, 1990 (the effective date of Article 3 of Public Act 86-1414), the mayor of Forest Park, with the advice and consent of the corporate authorities of the village of Forest Park, shall appoint 2 members of the Board for initial terms expiring June 1, 1991; 2 members for initial terms expiring June 1, 1992; and one member for an initial term expiring June 1, 1993. The successors of the initial members shall be appointed in like manner for 3 year terms from the date of appointment, except in case of an appointment to fill a vacancy for an unexpired term.