All formal hearings held pursuant to RCW 46.20.329 shall be conducted by a department hearing officer, who is appointed a referee for such purposes. In addition to the referees appointed by this section the director may from time to time appoint additional referees or may revoke the authority of any referee appointed by this section, but a record of such appointment or revocation of appointment shall be kept in the order registry in the director's office and may be examined at any time by any interested person.