After the time for filing exceptions and replies to exceptions expires, the hearings officer's proposal for decision will be considered by the Agency Chief and either adopted or modified and adopted. All final decisions or orders of the commission or the Agency Chief shall be in writing and signed. A final decision shall include findings of fact and conclusions of law separately stated. Findings of fact, if set forth in statutory language, shall be accomplished by a concise and explicit statement of the underlying facts supporting the findings. Parties shall be notified either personally or by certified mail of any decision or order, and a copy of the decision or order shall be delivered or mailed to any party and to his or her authorized representative.