After a sidewalk has been improved or constructed, either alone or in combination with a curb, the owner of land abutting the street area in which the sidewalk has been constructed is responsible for maintaining such sidewalk and curb in good repair.  If the City Administrator finds that any such sidewalk or curb needs repair, the City Administrator may post a notice on the adjacent property headed “Notice to Repair Sidewalk” (or curb) that will in legible characters direct the owner, agent, or occupant of the property immediately to repair the sidewalk or curb, or both in a good and substantial manner in accordance with the plans, specification and regulations of the City. The City Administrator will send by mail a notice to repair the sidewalk or curb, or both, to the owner, if known, of such property, or to the agent (if known) of the owner, directed to the post office address of the owner or agent when known, or if the post office address is unknown, the notice will be directed to the owner or agent at the address where the notice was posted. A mistake in the name of the owner or agent, or a name other than that of the true owner or agent of the property, or mistake in address will not invalidate said notice, but in such case the posted notice will be sufficient.