Don Chiofaro has laid out a six-year construction schedule for his downtown Boston Harbor Garage project and asked for some zoning relief in a project notification form filed with the Boston Redevelopment Authority Wednesday.

The filing fleshes out Chiofaro’s plans for the developer’s Harbor Garage site – a parcel that Chiofaro has previously called "the best site in the city." It lays out a six-year construction schedule for erecting two towers that would total 1.5 million square-feet of office, hotel, residential and retail space.

The proposed towers – a 40-story, 560-foot tall office building and a 59-story, 690-foot hotel and condo tower, to be connected by a 770-foot tall frame – would go vertical between 2014 and 2017. That construction would be preceded by a phased demolition of the existing garage and construction of the first phase of the towers’ underground parking.

Chiofaro eventually plans to replace the existing 1,475 above-grade parking spots with 1,200-1,400 below-grade spots.

The filing allows that Chiofaro’s project will need zoning relief. It speaks of "reconnecting Boston with its waterfront following the completion of the Greenway." The Greenway may prove to be the project’s biggest obstacle, though. City officials have said that development projects along the new downtown parks will have to conform to new regulations designed to protect the parks. Those regulations have not yet been formulated.