Special meetings of the Council may be called by the Mayor or by any three other members of the Council by writing filed with the City Administrator stating the time, place and purpose of the meeting. Notice of a special meeting shall be given by the City Administrator to each member of the Council by mailing a copy of the filing to all members who did not sign or issue the call at least three days prior to the time stated therein, or by personal service at least 72 hours prior to the projected time of meeting. Special meetings may be held without prior written notice to the Council when all Council members are present at the meeting or consent thereto in writing before meeting of those not present. Any such consent shall be filed with the City Administrator prior to the beginning of the meeting. Any special meeting attended by all Council members shall be a valid meeting for the transaction of any business that may come before the meeting. Meetings of the Council which are adjourned from time to time shall not be subject to the foregoing notice requirements; nor shall special meetings which, in the judgment of the Council, require immediate consideration to meet an emergency require the notice, but may be called by telephone communication or any other expeditious means. In all such cases, the members of the Council in attendance shall sign a waiver of notice which shall be made a part of the minutes of the meeting. Notice to the public and to news media shall be given as required by statute.