Upon substantial completion of all required appurtenant utility improvements and the connection of the same to the public system, the obligor may notify the town council in writing of such completion or substantial completion as provided for in N.J.S.A. 40:55D-53d and, after inspection and report of the town engineer, the town council may approve, partially approve, or reject the improvements. Where partial approval is granted, the bond of the obligor may be reduced, provided that 30 percent of the amount of the performance guarantee posted may be retained to insure completion of all improvements. Notice shall be given to the obligor as required by N.J.S.A. 40:55D-53e.