No surface drain shall be filled in by any person, either in whole or in part, unless such person first obtains a permit therefor, and unless there is installed in the fill or obstruction a culvert pipe, the size, strength, construction and grade of which must be adequate to carry the flow of surface waters in the drain and protect the public against cave-in, collapse and rapid deterioration. Upon the making of application to the city clerk for a permit, these factors must first be investigated by the city engineer, or street and water superintendent, or such other qualified person as the city council designates. The investigator shall report his findings to the council, which shall consider them in determining whether or not a permit shall issue. If a permit is issued, the culvert specifications shall be set out therein.