Emergency ordinances, ordinances raising revenue for the city governmental services, or for street improvements petitioned for by sixty per cent of the owners or by the owners of a majority of the feet front of property benefited and to be specially assessed for the cost thereof, and those making appropriations for current operating expenses of the city government, shall take effect upon passage and shall not be subject to referendum. All other ordinances shall take effect thirty days after passage in order to afford an opportunity for the filing of referendum petitions. (Amended 11-7-89)