Wherever water from roofs of adjacent buildings is drained or conducted under sidewalks from downspout drains to the street gutters through aqueducts or concrete troughs, these openings in the sidewalk shall be fitted with strong metal covers, which shall be securely held in place with screws or other fasteners which will not rust or corrode. Such cover shall be set flush with the surface of the sidewalk and securely bolted, fastened or so constructed that it cannot slip, shift or become out of alignment with the surface of the sidewalk. (Ord. 8590)