No ordinance, resolution or franchise shall become operative until 30 days after its passage by the council and approval by the mayor, except emergency measures necessary for the immediate preservation of the peace, health, safety or welfare of the city. An emergency measure shall not become immediately operative unless it states in a separate section the reason why it is necessary that it shall become immediately operative, and unless it complies with the requirements of MCC 2.20.050. [Code 2004 § 2-96.]