The remains of hundreds of people who lived in Philadelphia during the 18th century may have been dumped in a Conshohocken landfill this spring, according to a prominent Philadelphia archaeologist.

“It’s appalling,” said Doug Mooney, president of the Philadelphia Archaeological Forum, after reviewing PMC Property Group’s latest report on its construction and excavation efforts at 218 Arch St.

“It represents a loss of information,” he said. “It represents just a completely callous attitude on the part of the developer.”

Mooney made those conclusions based on how much earth was removed to a landfill during construction work in between two periods when archaeologists were collaborating with the developer.

The PMC report does not say that any remains were ever found and transferred to a landfill.

“It didn’t happen,” said PMC vice president Jonathan Stavin, when asked to comment. When remains were first identified, he said, the company immediately contacted the city coroner’s office.

Mooney, meanwhile, said he can “never know with certainty how many burials were removed.” But after reviewing the site maps and details in the report, he said he found “abundant information that you can connect the dots and draw that conclusion.”

Since last fall, the remains of nearly 500 people, some still in crumbling coffins, have been excavated from the Arch Street site, where PMC Property Group has been constructing condominiums. The remains were linked to a Baptist cemetery that was thought to have been moved in the mid-1800s. They are now being studied by volunteer archaeologists from Rutgers University, The Mutter Museum, and the College of New Jersey.

“There are no cemeteries of this size, of this early age that have been excavated and documented in Philadelphia,” Mooney said. “It’s an unprecedented opportunity to learn about the people that founded Philadelphia in the early 1700s.”

Skeletal remains first surfaced last year

Construction workers made an initial discovery of a box worth of bones in the fall of 2016. By March, as more remains and coffins surfaced, PMC allowed volunteer archaeologists in for about a week to excavate them for preservation and study. Months later, after news that remains were still being found, the developer hired a private archaeology firm at the urging of the city to oversee excavation efforts. As part of that process, PMC filed a petition in Orphans’ Court, seeking official permission to excavate, transfer and — ultimately — rebury the remains.

“We’ve done everything we believe has been required from us — and then some — to do the right thing,” PMC’s Stavin said in court in late July. PMC offered to remove and bury the remains at Mount Moriah Cemetery and, in the meantime, transfer them to the volunteer archaeologists for further study. The discovery has cost the company about $1 million in time and resources, Stavin estimated. The condominium development is slated to open in about a year.

Following the petition in Orphans’ Court, the judge assumed oversight of the remains. The developer brought in AECOM to oversee the excavation efforts, and it recently filed its final report in court.

During a hearing Monday morning, Judge Matthew Carrafiello said he hadn’t had a chance to review the report yet. In the meantime, no one objected to PMC’s request for a six-month extension to finalize reburial details for the hundreds of remains that have been properly excavated.

Marc Zecca, a lawyer representing Mooney and the Philadelphia Archaeological Forum, has asked to comment on the report and its implications. The judge is reviewing that request.