The Commuter Building block, with its attached pedestrian bridge to the ferry terminal, is bound for redevelopment.

Martin Selig Real Estate acquired 815 Western Ave Commuter Building block. Slated to be called 75 Marion, the four story building will be renovated into an 18-story mixed-use tower with 200-300,000 square feet of office space, 25,000 square feet of retail, and 150 residential units.

Martin Selig Real Estate paid $44 million last year for the property. The proposed new Windermere Building, now using the address of 75 Marion St., is being designed by Perkins + Will in collaboration with Jim Olson, of Olson Kundig Architecture.

The basic program is for a 15-story mixed-use tower. It will have about 200-300K square feet of offices on levels two through four, and six through nine.

About 106 apartments are planned for level five, and levels 10-15. There will be a roof deck with expansive views of Elliott Bay, and a rooftop amenity area.

There will also be some 21,000 square feet of ground-floor retail and commercial space. Three levels of underground parking will have about 278 stalls.

Total project size, including the parking, is estimated at 504,000 square feet. The anticipated timeline is to start construction in early 2020, after the viaduct is removed, with completion in early 2022.

Demolition plans for the block indicate it’ll be used for construction staging for Kiewit’s viaduct and waterfront work.

The preferred design scheme is called “erode,” taking its cues from the wind- and sand-scoured driftwood and rocks one finds by the seashore.

A 7,000-square-foot fifth-floor terrace on the north side could be used by both office tenants and residents.

Parking will be accessed from Western Avenue. Entries for both the office and residential tenants will face Alaskan Way.