Any city or statutory city in the class mentioned in section 420.01 which may wish to avail itself of the provisions of this chapter, shall do so by an ordinance expressly accepting the provisions hereof. The ordinance shall be adopted in the same manner as other nonemergency ordinances, but at least 30 days shall elapse between its introduction and final passage by the governing body. This chapter does not apply to any city until the adoption of such ordinance.