(a) When a vacancy shall occur on the board by death, resignation, or expiration of the term of office, or in any other manner, the vacancy shall be filled by the city council or governing body of the city.
(b) In the event a vacancy occurs during the term of office of any commissioner, except as caused by the normal expiration of his or her term, his or her successor shall fill the unexpired term caused by the vacancy, and at the normal expiration of the term, the council shall fill the vacancy by the appointment of a commissioner for a period of six (6) years.