It is the duty of the owner and of the occupant of any lots abutting upon any sidewalks, either in front or at the side or both, in the city, to cause to be removed from such sidewalks all snow and ice and to keep such sidewalks at all times free from the accumulation of snow and ice; provided, that where there shall be ice or compacted snow on any such sidewalk of such a character as to make it practically impossible to remove the same, the sprinkling of salt, ashes, sand or other similar chemicals or materials on the accumulation of ice or snow in such a manner as to make such sidewalk reasonably safe for pedestrian travel shall be deemed a sufficient compliance with the provisions of this chapter until the said ice or snow can be removed. Ref.: Deposit in gutters, see Section 12.12.100 of this title. (Prior code § 14-501)