No person, other than a proper duly authorized officer of the City, shall make any opening or excavation in any sidewalk, street, alley or public ground without a permit to do so. Any such person desiring an excavation permit shall file with the City Engineer a written application setting forth the location, kind, number and size excavation to be made, and the time during which such excavation is to remain open. These provisions shall not apply where openings are made for public use by the City or by contractors performing work pursuant to City contracts.
(1964 Code §519.51)