The Board of Zoning Appeals shall consist of 5 members appointed by the Mayor for a period of 3 years, subject to the confirmation of the Council. The members of the Board shall serve without compensation, and shall be removable by the Mayor for cause upon written charges and after public hearing. The terms of not more than 2 members shall expire in any one calendar year. The Mayor shall designate one of the members as chairperson. The Board of Zoning Appeals may employ a secretary and other employees. The Mayor shall appoint two alternate members for a term of 3 years. An alternate shall act, with full power, only when a member Board refuses to vote because of interest or when a member is absent. Vacancies shall be filled for the unexpired terms of members whose terms become vacant.