(c) This penalty shall be assessed in addition to any other civil penalty otherwise provided for by law. Notice of assessment of a penalty pursuant to this section shall be made by service in hand, or by certified mail, return receipt requested, and shall state the amount of the administrative penalty, the date the penalty shall be due, a statement of the violator's right to an adjudicatory hearing pursuant to chapter 30A regarding the assessment, a statement of the actions the person may take in order to avoid assessment of additional penalties or to avoid waiving the right to a hearing relative to the penalty and the manner of acceptable payment if an election to waive a hearing is made. A person shall be deemed to have waived all right to an adjudicatory hearing unless, within 21 days of the date of the department's notice, the person files a written notice, by hand or by certified mail, return receipt requested, requesting such adjudicatory hearing. In the event that such request is not received in accordance with this section, the proposed administrative penalty shall become final and payment shall be due in accordance with the notice.