It is the duty of the occupant of any lot or piece of ground abutting upon any street to keep the sidewalk or gutter clean and to remove all materials, snow or ice, trash, weeds, refuse, rubbish, or hazards of any kind, and to keep the sidewalk and gutter in good repair. If there is no such occupant other than the owner, it is the duty of the owner to do the same. It is unlawful for the owner or occupant of property to permit the sidewalk or sidewalk area to become a hazard to persons using the sidewalk, or sidewalk area. (City Code 7-1-7: Allowing Hazardous Conditions on Sidewalk)