Maryland Environment Section 8-504

      (a)      (1)      Except as otherwise provided, any notice, order, or other instrument issued by or under authority of the Department under this subtitle may be served personally or by mailing a copy of the notice, order, or other instrument by certified mail, return receipt requested, bearing a postmark from the United States Postal Service, to the person affected at the person's last known post office address as shown by the Department's files or records.

            (2)      Proof of service may be made by the sworn statement or affidavit of the person who mailed the notice, order, or other instrument.

            (3)      The sworn statement or affidavit shall be filed with the Department.

      (b)      Any notice that requires filing of a report, attendance at a hearing, or both shall be served at least 10 days before the earlier of:

            (1)      The time set for the hearing if any; or

            (2)      The time set for the filing of the report, if any.