The Commission shall consist of twelve members. All members should have to the highest extent possible, a recognized knowledge of a known interest in historic preservation together with a determination to work for the overall improvement of the quality of this City's physical environment. At least two members of the Commission shall be preservation-related professional members from the fields of architecture, architectural history, history, archeology, planning or a related discipline. One member shall be the Mayor of the City, one member shall be designated by the Planning Commission and shall serve a term concurrent with membership on such Commission. One member shall be a member of Council designated by Council at the first meeting of alternate calendar years, and shall serve a two-year term. Three members shall be appointed by the Mayor from recommendations made by the Richland County Historical Society and shall serve two-year terms. Five members shall be appointed by the Mayor because of their special expertise or interest and shall serve two-year terms. One member shall be from the City's Community Development Department staff, designated the Historic Preservation Officer. Terms of office shall be staggered. All members of the Commission shall serve without compensation from the City. Vacancies caused by death, resignation or otherwise shall be filled for the unexpired term in the same manner as original appointments are made. Vacancies shall be filled within sixty days unless extenuating circumstances require a longer period.