The heads of the various administrative departments, including department directors and the chiefs of fire and police, shall be immediately responsible to the city manager or the city manager's designee for the effective administration of their respective departments and all activities assigned thereto. Except as may otherwise specifically be provided by this Code, the city manager or the city manager's designee may set aside any action taken by a department head and may supersede the department head in the functions of the department head's office. Two or more departments may be headed by the same individual. In addition to any duties or responsibilities assigned by this Code, the heads of departments may also serve in such additional capacities and have such other duties and responsibilities as may be assigned by the city manager. For a vacancy in any office or during the absence of any department head, the city manager may designate an interim acting head of the department. All department heads shall keep informed of the latest practices in their respective fields and shall inaugurate, with the approval of the city manager or the city manager's designee, such new practices as shall appear to be of benefit to the city and to the public. (Code 1979, § 2-7)