Upon the abandonment of a particular project authorized under this chapter or upon the expiration of three years from the final approval of a planned unit development which has not by then been completed, or commenced with an extension of time for completion granted, the authorization shall expire and the land and the structures thereon may be used only for a lawful purpose permissible within the zone in which the planned unit development is located. (Ord. 2020 § 15, 1994; Ord. 190 Art. XII § 12.3, 1964)