Prior to considering the adoption of a proposed solid waste management plan or an amendment thereto, the Board of Commissioners shall conduct at least one public hearing within the District on the proposed plan or amendment. The hearing shall be warned by the publication of a notice in a newspaper of general circulation in each member municipality at least 15 days prior to the hearing, and by sending a copy of the notice by certified mail, return receipt requested, at least 15 days prior to the hearing, to the legislative body of each member municipality.