The six fatalities included Anne Bryan, a 24-year-old artist and daughter of Nancy Winkler, the city treasurer. Winkler and her husband, Jay Bryan, started a petition drive to turn the site into a public park.
"Our message today is to thank everyone for recognizing that this was the right thing to do, and we appreciate that we've all come together and found a solution really quicker than I had imagined," Winkler told reporters.
Asked about her hopes for the project, she said: "We would like a beautiful park that reflects the importance of human life."
The Pennsylvania Horticultural Society has been working on an overall park design to be presented to the neighborhood April 1 at the College of Physicians and Surgeons, the adjacent building on 22d Street.
The Pennsylvania Academy of the Fine Arts plans a competition to design a memorial in the park for the victims.
Fund-raising is also under way, with about $50,000 raised so far toward an estimated $250,000 in total costs, according to Gerard H. Sweeney, president of Brandywine Realty Trust, finance chairman of the 22d & Market Memorial Committee.
Public contributions can be made through the Horticultural Society at www.pennhort.net/memorial or the website www.indiegogo.com/projects/22nd-and-market-memorial-garden
Winkler and John White, chairman of the PFM Group, are the committee's cochairs.
Nutter endorsed the park proposal months ago, but the land is still owned by the Salvation Army, whose thrift shop was destroyed when a four-story brick wall at an adjacent demolition site collapsed on top of the store.
Six inside were killed and 13 customers and employees were injured, as was a heavy-equipment operator at the demolition site.
Nutter confirmed city officials had discussed finding another site where the Salvation Army might build a thrift shop.
Independent of those discussions, the Salvation Army board decided on its own to donate the 22d and Market property for the memorial, Nutter said.