Within thirty (30) days following the effective date of the ordinance codified in this chapter, and thereafter within thirty (30) days after first entering upon the duties of his office, the mayor and each member of the city council shall, in addition to any duly authorized deputy, designate such number of emergency interim successors to his office and specify their rank in order of succession after any duly authorized deputy so that there will be not less than three (3) duly authorized deputies or emergency interim successors or a combination thereof for the office. (Prior code §1-70 (a))