The Peebles Corp. has revealed new details and a rendering of its massive air rights project featuring labs and affordable housing in the Back Bay.

The firm filed a project notification form with the Boston Planning & Development Agency on Tuesday, as first reported by the Boston Business Journal.

In April, Peebles filed a new plan for the parcel after scrapping its previous plans for condos and a luxury hotel on the site. The new proposal calls for a 422K SF building with 300K SF of labs and 125 affordable apartments.

The lab building will stand at 12 stories and 178 feet tall, while the residential part of the project will have 10 stories and will rise 120 feet, according to the filing.

The firm is also considering making the project gas-free, including the lab space. If Peebles is able to achieve this, Parcel 13 would mark a milestone for Boston as the first gas-free lab in the city, according to BBJ.

Peebles won the bid for Parcel 13 from the Massachusetts Department of Transportation in 2015. MassDOT required developers to make upgrades to the adjacent MBTA Hynes station to comply with handicap accessibility laws, according to Banker & Tradesman. Peebles is expecting to pay $54M toward upgrades to the station.

Parcel 13 isn't the only air rights project in the works over the Massachusetts Turnpike. Samuels & Associates' Parcel 12, a 450K SF office and lab tower, just completed the deck over the highway in June.

In March, Peebles won another bid from MassDOT for Parcel 25, a 1.4-acre site near South Station. Peebles proposed a 585K SF, 21-story building, including 309K SF of lab and research space, 218 apartments and ground-floor retail. The vacant lot sits above I-93 and has lain dormant since 2016 after it was unsuccessfully put out to developers.

“This is something we have been involved in a very long time. I enjoy this part of the process,” Peebles Corp. CEO Don Peebles told Bisnow in 2020. “We’re not going to get to a point where we’ve spent a huge amount of money and not cross the finish line.”