Any order or notice issued pursuant to this chapter shall be served upon the owner, operator, occupant or other person responsible for the condition or violation, either by personal service, or by delivering the same to and leaving it with some person of responsibility upon the premises, or by affixing a copy thereof in a conspicuous place at or near the entrance to such premises or by mailing a copy thereof to such person by registered or certified mail to the last known address with return receipt requested. (1975 L.M.C., ch. 23, § 1.)