In the Newtown Creek Subdistrict, the Chairperson of the City Planning Commission shall allow for the phased implementation of all required publicly accessible areas upon certification to the Commissioner of Buildings that a plan has been submitted that provides for an amount of public access area proportionate to the amount of floor area being developed or enlarged in each phase. For any development or enlargement located within 100 feet of a shoreline, the initial phase shall provide, at a minimum, the required shore public walkway and any adjacent supplemental public access areas located between such development or enlargement and such shore public walkway, as defined in Section 62-11. For any development or enlargement that fronts upon 54th Avenue, the initial phase shall provide, at a minimum, the required publicly accessible private street.