A soaring luxury apartment tower planned for the last undeveloped corner of Rittenhouse Square got the green light to move forward from the Philadelphia Historical Commission’s Architectural Committee on Thursday.

The committee’s recommendation of the 1911 Walnut St. tower paves the way for a likely approval from the full commission and an early 2019 groundbreaking.

The project’s owner and developer, Southern Land Company, bought the 1907-1914 Walnut Street site and an adjoining parcel at 1906-1920 Sansom Street in 2015 and have worked for past two years to build public support for the planned 48-story, nearly 600-foot-tall skyscraper. As a result of this long-burning consensus-building process, the mostly high-end residential and retail development will preserve the vacant Warwick Apartments and Rittenhouse Coffee Shop buildings on the Sansom Street lots and reuse them as affordable housing.

The current plan for the two historic buildings includes 30 units of housing for veterans at 60 percent of area median income (AMI) or less. In the Philadelphia region, the 2017 median income was estimated at $83,200 so the income limit for the building would be $49,920 for a family of four.

In the tower itself, six or seven of the tower’s 185 rental units will be made available for those making 80 percent of AMI, which equals out to $46,600 for one person, $59, 900 for a couple or $71,900 for a family of three. In addition to the apartments, the building will include hotel rooms and on the top floors, 80 lux condos expected to sell at a starting point of $2.5 million.

These various concessions and the long civic engagement process that birthed them didn’t satisfy all of Nashville-based Southern Land Company’s new neighbors.

“The idea of a 48-story building going in across the street frankly scares us,” said Ben Heizen, a representative of the Church of the Holy Trinity, which neighbors the site. “I thought I heard [Southern Land’s lawyer] say that the neighborhood groups had all agreed to this proposal. That simply isn’t true.”

Heizen said he wanted vibration testing done in the basement of the church and professional photos taken of both the interior and the exterior, so they could measure damage construction might cause. He also asked the Architectural Committee to delay its consideration of the project. They refused, noting that neighbor relations were not within their purview.

Dustin Downey, the principal for this Southern Land project, attempted to address Heizen’s concerns and those of David Schwartz, owner of 1902 Sansom, who was irked that he hadn’t been included in the outreach process. Schwartz’s building is next door to the vacant historic buildings, and he fears the disruption caused by their extensive rehabilitation. At almost 600 feet tall, the planned development will dwarf 1902 Sansom and other nearby buildings.

“This civic engagement process was a new process for us and it hasn’t always been absolutely crystal clear,” said Downey, noting that they’d been told not to engage one-on-one with individual parties. “On public record I will give you my personal guarantee and my corporate guarantee that we will do everything we can [to assure Trinity and other near neighbors].”

Downey noted that the company altered their plans for the project’s foundations to mitigate vibrations. Instead of drilling into the rock below, they will instead be pouring a huge concrete mat slab foundation to build atop of. The second Comcast tower, which stands at 1,121 feet and 60 stories, executed a similar maneuver.