The public works superintendent may issue a permit to construct street improvements in the city. Such permit shall provide the specifications, lines and grades to be followed in building such street improvements and such street improvements shall be constructed under the direction of said public works superintendent. It shall be unlawful for any person to construct street improvements in the city without first obtaining a permit so to do and unless such street improvements conform to the specifications, lines and grades prescribed by the city engineer. [Code 2000 § 9-2-6].