Security upon conditional approval. If it is clear at the time of the Planning Board's determination that any condition or restriction imposed by the Planning Board cannot be fulfilled or complied with prior to the issuance of a certificate of occupancy, or if subsequent to such determination and prior to the issuance of a certificate of occupancy it becomes impractical or a hardship for the applicant to fulfill any condition or comply with any restriction prior to the issuance of a certificate of occupancy, then the Planning Board may, in its discretion, after appropriate inquiry to establish an estimate from a competent source of the cost of fulfilling such condition or complying with such restriction subsequent to the issuance of a certificate of occupancy, make the issuance of the certificate of occupancy contingent upon the applicant first providing security which meets the requirements and conditions of Paragraph (c) of Subdivision 9 of § 277 of the Town Law, as same may be amended from time to time, in a specified amount not exceeding 120% of the estimated cost of completion of such condition or compliance with such restriction, to secure the completion of such condition or compliance with such restriction within a period of time to be set by the Planning Board, not exceeding one year. For good cause shown, the Planning Board at any time may extend said period beyond one year, provided the total period does not exceed two years measured from the date of issuance of the security. The amount of such security may be proportionally reduced from time to time upon the approval of the Planning Board as performance thereunder progresses.