The Planning Board shall grant an extension of any site plan or subdivision approval for a period determined by the Board, but not exceeding one year from what would otherwise be the expiration date, if the developer proves to the reasonable satisfaction of the Board that the developer was barred or prevented, directly or indirectly, from proceeding with the development because of delays in obtaining legally required approvals from other governmental entities and that the developer applied promptly for and diligently pursued the approvals. A developer shall apply for this extension before: 1) what would otherwise be the expiration, or 2) the 91st day after the date on which the developer receives the last of the legally required approvals from the other governmental entities, whichever occurs later. An extension granted pursuant to this section shall not preclude the Board from granting any other extensions permitted herein or by any other law.

No subdivision plat shall be accepted for filing by the County Recording Officer until it has been approved by the Planning Board as indicated on the instrument by the signature of the Chairman and Secretary of the Planning Board or a certificate has been issued pursuant to Subsection 54-21.15. The signatures of the Chairman and Secretary of the Planning Board shall not be affixed until the developer has posted the guarantees required pursuant to subsections 54-15.4 and 54-21.18.