On application of any interested resident or on its own initiative, the Planning Commission may require that the owner of any property subject to a nonconforming use or structure establish the legality of such use or structure by sufficient evidence at public hearing before the Planning Commission following at least ten days’ notice. Any interested person may present evidence at such hearing and such hearing may be continued by the Planning Commission for the taking of additional evidence. Any interested person may appeal the decision of the Planning Commission to the City Council by written notice of appeal filed within seven days after the Planning Commission’s decision is rendered, in which event the City Council shall, after ten days’ notice, hear the appeal. If the owner prevails, he shall be issued a certificate of nonconforming use, or structure, as the case may be, and a copy of such certificate shall be filed with the City Clerk, who shall maintain an index of all such certificates. If he does not prevail, any such illegal use shall be abated within thirty days, and any such illegal structure shall be abated or made to conform to existing zone regulations within one hundred eighty days after final decision unless additional time is granted by the Planning Commission or by the City Council on appeal. (Ord. 89-1 § 1, 1989.)