It shall be unlawful for any person to install, or to cause or permit to be installed any service pipe or main pipe conduit, duct, tunnel or other structure, except manholes, culverts and catch basins, in any public place at a distance of less than two feet below the established grade of such public street or alley or if the grade has not been established less than two feet below the surface of such street, alley or other public place.
(`83 Code, § 12.08.100)