"The idea that we're in any way giving up our interest is a misnomer," Gillison said. "I don't see this as deferring; I see it as partnering."
The burial ground, purchased in 1810 by Richard Allen, founder of Mother Bethel AME Church, sold to the city in the 1890s, and subsequently largely forgotten, reemerged last year as a planned $500,000 playground renovation loomed.
Independent historians Terry Buckalew and, in recent months, Sheila Jones have now identified more than 2,500 people buried on the site, at the corner of Lawrence and Queen Streets. Archaeologists estimate the remains of more than 5,000 African Americans are buried in the quarter-acre cemetery, which underlies about a third of the Weccacoe site.
Certaine has been concerned that the city in general and the mayor's office in particular have not exercised appropriate control over a site of "enormous historical significance."
Founders of Bethel Church, civic leaders, musicians, laborers, craftspeople, and the poor, many unaffiliated with Mother Bethel, are buried there.
"They are the founding generation of black Philadelphia," historian Richard Newman, incoming director of the Library Company of Philadelphia, has said. "To have something like this is absolutely vital to the story of African Americans in America."
Last year, the Philadelphia Historical Commission, acting on an application submitted independently by Buckalew, certified the Bethel site, meaning the commission must approve any construction or disturbance.
Certaine and others, including Michael Coard, leader of the Avenging the Ancestors Coalition, have expressed concern that the city has delegated decision-making and planning to second-tier officials and has not acted quickly to forestall potential threats to the burial ground.
Gillison met last week with many of those involved. He told them that renovation planning had been suspended and that the Water Department is looking at how to address the threat posed by an active 180-year-old water main on Queen Street.
He asked the department to report by late April on what should be done to prevent what Buckalew called a "disastrous" break leading to "bones washing down Queen Street."
A large mulch pile that sits in a depression over the cemetery will be removed with archaeologists present, Gillison said.
No decision will be immediately forthcoming on whether to do an engineering study of the site, which would help explain why the depression exists and what has caused multiple cave-ins on the burial ground over time.
Councilman Mark Squilla, whose First District includes the playground, said the best way to proceed "hasn't been decided yet. That's a process that should include everybody."
He said he's willing to discuss all possibilities for the site, even "maybe we find another place for a playground, I don't know. Everybody has ideas."
The Rev. Mark Tyler, pastor of Mother Bethel, attended the Gillison meeting but could not be reached for comment. Duncan Spencer, a leader of the Queen Village Neighbors Association and the Friends of Weccacoe Playground, declined to comment.
"You come up with a compromise. That's why you have these meetings," said Squilla. "At the end of the day you come up with a plan. It's not brain surgery."