Except as otherwise provided in this Charter, ordinances may be proposed and submitted to popular vote by initiative and referendum under the procedure set forth in the Ohio Revised Code. If the Council is required to pass more than one ordinance or resolution to complete and pay for any public improvement, the referendum shall apply only to the first ordinance or resolution to be passed and not to any subsequent ordinance or resolution in the series relating thereto. Council shall not repeal any ordinance approved by the electors. Repeal of such ordinance shall be subject only to the referendum.