It is unlawful for any person, firm, or corporation to so erect, construct or place any building or other structure or any part of any building or other structure, that the same, or any part thereof, shall rest upon or the weight or load thereof shall be borne by any part or portion of the conduit constituting the improved channel of Mill Creek constructed by the city, as such conduit now exists or as the same may be hereafter altered or constructed by said city. (Prior code § 7834)