The prayer service was to be an opportunity "to reconnect spiritually with the ancestors buried there and an opportunity to say a public prayer over the 5,000 souls buried there," Certaine said.
The burial ground - now beneath part of the Weccacoe Playground on Lawrence Street between Catharine and Queen - was purchased by Richard Allen, the founder of Mother Bethel AME Church, in 1810. In the late 1890s, the city purchased the cemetery, which had been filled to capacity with six to seven layers of bodies on top of each other, historian Terry Buckalew said.
The Friends of Bethel Burying Ground announced its formation last month after archaeological studies in November revealed that thousands of people were buried beneath a portion of the playground adjacent to Queen Street.
Buckalew pushed for the studies after learning three years ago that the city's Parks & Recreation Department was planning major playground renovations.
Buckalew said at first, the city seemed ready to go ahead with renovations despite knowledge of the burial ground. That's when he filed paperwork to get the site onto the city's Register of Historic Places.
"This was the first time a group of free African-Americans purchased land that was not attached to a church," Buckalew said. "That was in April 1810. It's quite a legacy."
He and other supporters are also trying to have the burial ground listed on the National Register of Historic Places.
Jeff Hornstein, president of the Queen Village Neighbors Association, said the neighborhood also supports protecting and commemorating the burial ground.
"When we first learned about the burial ground, I was excited," Hornstein said, adding that he thought it was "outrageous" there wasn't already a historic designation there. "I'm living half a block away from perhaps the most important black graveyard in the country."
Hornstein said for the last two years, the position of the Queen Village group has been that the renovations should not disturb the burial site and that the ground's history should be told.
The burial ground runs underneath about a third of the playground, including a small community center and about 20 percent of the tennis courts.
Duncan Spencer, president of Friends of Weccacoe Playground, proposed that the neighborhood give up the tennis courts, and instead use the space for soccer.
Hornstein said there isn't much controversy over the grounds, because all are in agreement that the site should be honored.
"There's no fight here," he said. "The city has been managing this process very well."
But Certaine and Buckalew said the issues aren't as close to resolution as some may think.
"We want that building gone," Buckalew said of the community center. "There are two public toilets. . . . There's no reason you should have public toilets over graves."
Hornstein said he would prefer to keep the community center because it is the only public space in the area. He said he had also hoped to renovate the building and turn it into a tutoring center for neighborhood children. Now, he said, he would also like to see part of the center include historical information about the burial ground and those laid to rest there.
The Rev. Mark Tyler, pastor of Mother Bethel, at 6th and Lombard streets, said he had not been scheduled to take part in the prayer service today. He said he declined to participate because he hadn't been included its planning. "I am open to planning a shared remembrance or prayer service . . . provided we are at the table together doing the planning," Tyler said.
Tyler said descendants of Richard Allen have no problem with a playground being adjacent to the burial site.
The burial-ground group made some headway after meeting earlier this month with Mayor Nutter's chief of staff, Everett Gillison, and other city officials, Buckalew said.
After that meeting, he said, the Water Department agreed to either block off or replace a water line that supporters feel is threatening the burial ground.
"There is a large water main under Queen Street that was put in 1835 that is very close to the bodies," he said. "It has to be shut down or a new pipe put in. The city wouldn't want the bones of those buried people washing down Queen Street."
Certaine said he is most concerned that the city takes charge of the historical site.
"This is serious Philadelphia history and African-American history," he said. "It has to be treated that way by a city administration that is responsible for the property."
On Twitter: @ValerieRussDN