After final passage of an amendment to the UDO, the ordinance shall be published pursuant to Section 19 of the City Charter, and except as otherwise provided in the Charter, shall be subject to permissive referendum as provided in Article X of the Charter. The amendment to the UDO shall become effective at the expiration of thirty (30) days after such publication following final passage, or, if the ordinance be submitted at a referendum election, upon a favorable vote of a majority of those voting thereon except as otherwise expressly provided by the Charter.