Maintain all weeds and other vegetation located within 10 feet of any combustible fence or an edge of that portion of any highway, street, alley or driveway improved or used for vehicular travel or for other vehicular purposes at a height of not more than 3 inches. This shall not require the removal of trees, ornamental shrubbery or plants which are used as ground cover, provided such do not provide a ready fuel supply to augment the spread or intensity of a fire, nor require the removal of native shrubs which meet the requirements set forth in Section 57.4906.5.1.1.1.