The town council shall either approve, partially approve or reject the improvements on the basis of the report of the town engineer and shall notify the obligor in writing, by certified mail, of the contents of such report and the action of the reviewing board with relation thereto, not later than 65 days after receipt of the notice, in writing, from the obligor of the completion of the improvements. Where partial approval is granted, the obligor shall be released from all liability pursuant to its performance guarantee, except for that portion adequately sufficient to secure provision of the improvements not yet approved. (See subsection 19-7.10). Failure of the town council to send or provide such notification to the obligor within 65 days shall be deemed to constitute approval of the improvements, and the obligor and surety, if any, shall be released from all liability pursuant to such performance guarantee.