(1) A final plat which meets all of the requirements of this title shall be submitted to the Administrator for processing and approval within five (5) years of the date of preliminary land division approval. The final plat may be presented to the County at any time during the period of preliminary approval. The preliminary approval shall be null and void unless a plat meeting all conditions and requirements for final approval is received during the original five (5) year approval period.

(2) The Board of Commissioners may approve a one-time twelve (12) month extension in time for the filing of a final plat. Requests for such extensions in time must be made no later than ninety (90) days prior to the expiration of the preliminary plat approval. All requests for an extension of time must contain a certification by a professional engineer registered in the State of Washington that improvements totalling at least fifty (50) percent of the cost of all required improvements have been installed. No bond in lieu of improvements shall be allowed for any land division for which an extension of time has been previously approved.