Now, the Related Companies' project could face an even bigger hurdle.
"I will strongly oppose any efforts to bypass the ULURP [uniform land use review procedure] process if Related ends up moving forward with its plans," Quinn wrote.
Public scrutiny could call into question the fate of the 32,000-square-foot project slated for the open space at 222 E. 93rd St.
Under the deal Related struck with the city in 1983, the developer was only required to keep the space open to the public for 25 years. After that agreement expired in 2008, the company began gearing up to build. It closed the playground in September 2011.
But advocates from the group Save Ruppert Playground believe they recently uncovered a wrench in Related's plans. They claim that nothing can be developed on the playground without a land use change.
If the building is considered a "minor modification" to the site, it would simply be handled by the City Planning Commission without public input. But if it's deemed a "major modification," then the City Council must review the project and hear community input. Many elected officials are pressing for the public review.
"With its basketball, tennis, handball courts, a tot lot and sitting areas, Ruppert Playground was cherished by this community," Councilwoman Jessica Lappin, who represents the area, told Community Board 8 members Wednesday.
She, too, wrote a letter to City Planning calling for a full public review, and City Councilman Dan Garodnick spoke in support of it, too.
"I think we have some good momentum to our fight," Lappin added. "I can't really imagine a bigger change in public space use. It deserves a ULURP [uniform land use review procedure] hearing and for the community to have a say."
Geoffrey Croft, of NYC Park Advocates claimed that Related had misrepresented the project initially as one that would not need a land use change.
"The evidence strongly supports that City Planning should determine that a change of this magnitude is subject to ULURP," he said.
"The decision to remove a heavily used public playground in a community board that ranks dead last in the amount of publicly accessible open space in the entire city and has the highest density is clearly a major land use decision," he added.
Many residents, including Gillian Begelman, have lamented the park's closure. The mother, whose son is one of 75 tots in a daycare center at the nearby Ruppert Towers, told CB8 members, "Now these children don't have a safe place to play."
Neighbors also worry about the potential traffic and construction concerns that a big tower with a medical center could bring.
"Our plan will bring an important cancer research and treatment center to New York City," a Related spokeswoman said Thursday.
"Not only will we be able to offer a first-of-its-kind facility in the region, enhancing New York City’s reputation as the leading destination for cancer care, but we will also create hundreds of jobs and critical affordable housing," she added.
The spokeswoman did not immediately respond to a request for comment regarding the land use requirements.
Community Board 8 voted to approve the plan be subject to the land use review process.