(a) In addition to the penalties provided for the violation of this subchapter, the City Manger may cause written notice of the section violation of this subchapter to be served personally upon the owner, occupant, or person having charge of the property involved, or by sending to that person by certified mail, or by posting a copy thereof in a conspicuous place on the premises or property involved. This notice shall state the nature of the public nuisance and the time, not less than seven days, within which it shall be abated No person so notified shall fail to refuse to comply with the notice.