Construction of the PID project shall begin within eighteen months from the date of the final approval of the plan.

An extension of time for beginning construction may be requested in writing by the applicant and such extension not exceeding six months may be granted by the council. If construction is not begun within one year or within the time for which an extension has been granted, the plan shall be considered abandoned and the development of the property shall be subject to the normal requirements and limitations of the underlying zone and the subdivision ordinance. (Ord. 758 §1 (part), 1985).