The original deadline for proposals was May 6.
JEA extended the deadline to allow its board of directors, Duval County Public Schools and the Jacksonville Transportation Authority to adopt a plan to transfer small parcels adjacent to the site to accommodate construction of an access road.
That road would connect Prudential Drive with Broadcast Place and the Kings Avenue parking garage.
The school board approved its part of the land swap July 1, followed by the JEA board Aug. 19 and the JTA board Thursday.
The access road is estimated to cost $10 million to construct and no funding source has been identified, although the city plans to seek a Florida Department of Transportation grant for the project.
Following approval by all involved parties of property transfer agreements to allow access to the former Southside Generating Station, JEA has set noon Oct. 7 as the final deadline to accept requests for proposals to purchase and develop the 30-acre parcel along the Southbank Downtown.