Developer Buccini/Pollin Group plans a 31-story residential tower on the grounds of Center City's Sheraton Society Hill Hotel on Dock Street, which it acquired earlier this year.

The Wilmington, Del.-based developer was granted zoning permission last week for a 273-dwelling-unit "addition" to the existing hotel building, according to permit information posted to the website of the Philadelphia Department of Licenses and Inspections.

The tower would be at the southern part of the 2.5-acre property, which is currently open space with some landscaping, the Society Hill Civic Association community group said in an email to its members Friday.

A Buccini/Pollin affiliate bought the 364-guest-room Sheraton hotel property in March from RLJ Lodging Trust of Bethesda, Md., for $95.5 million. Buccini/Pollin said at the time that it planned a complete makeover of the property and that the hotel's brand would change.

A message seeking additional details from the company Friday about the residential tower plan was not immediately returned.

The developer is expected to present the proposal to the Society Hill Civic Association and to the city's Civic Design Review board, according to an e-mailed notice this week from the Society Hill Towers Owners' Association, which represents residents of a condo tower complex across Dock Street.

As part of Philadelphia's planning process, the Society Hill community group and city design board are entitled to offer nonbinding feedback for big development projects.

"We are in touch with the [civic association] and hope we will be working closely with them in order to deal with this development," the tower association said in its notice.

Buccini/Pollin's other major Philadelphia project is the apartment building finishing construction at the former site of National Products restaurant-supply business in Old City.