An emergency ordinance shall be introduced in the form and manner prescribed for legislation generally, except that each emergency ordinance shall declare that it is necessary for the immediate preservation of the public peace, health, safety or welfare, and shall clearly specify the nature of the emergency.
      Upon successful motion to treat an ordinance as an emergency, and to dispense with the public hearing when appropriate, an ordinance may be adopted as an emergency ordinance by an affirmative vote of no less than five Council members. If an emergency ordinance fails to receive an affirmative vote of at least five Council members, but receives a vote of at least four Council members, the ordinance shall become effective as non-emergency legislation.