The board of commissioners of the authority may create an executive committee of the board of commissioners. The board may provide for the composition of the executive committee so as to afford, in its judgment, fair representation of the member municipalities. The executive committee shall have and exercise such of the powers and authority of the board of commissioners during intervals between the board’s meetings as may be prescribed by its rules, motions or resolutions. The terms of office of the members of the executive committee and the method of filling vacancies therein shall be fixed by the rules of the board of commissioners of the authority.