Researcher Jarrod Burks conducts the ground-penetrating radar study at Walter C. Pierce Park in Adams Morgan to determine the layout of the Civil War-era African American cemetery buried beneath the park. (Astrid Riecken/For The Washington Post)

On a May afternoon in 2001, a group of volunteers cleaning up trash in Walter C. Pierce Community Park in Adams Morgan found a bone that appeared to be a human femur. The Washington region was enthralled at the time by the search for missing former government intern Chandra Levy, and the bone’s discovery sent murmurs rippling through the cleanup crew. Finally, a nurse in the group examined the bone. It’s not Chandra, she told the group. This bone is very old.

Beneath Walter Pierce Park are two adjacent historic cemeteries: the quarter-acre Burying Ground or Place of Interment for the Society of Friends or Quakers, which dates to 1809, and a 63 / 4-acre African American cemetery, which operated between 1870 and 1890. At the peak of its use, Mount Pleasant Plains Cemetery was the largest African American burial ground in the District.

On Saturday, at a memorial and celebration in the park from 11 a.m. to 1 p.m., the Walter Pierce Park Archaeological Team will release a report asserting that thousands of bodies still lie beneath the dog run, soccer field, basketball court and playgrounds of the heavily used park. It also will ask the city to protect the park from further development and to create space for a memorial.

“The math shows there are probably still thousands of graves here, but who knows what shape they’re in?” says Mary Belcher, an Adams Morgan resident who, along with the late Howard University anthropologist Mark Mack, spearheaded the project.

Until recently, the city’s official position was that few if any graves remained, or that if they did, the grounds were so muddled by a century of development that it hardly mattered. In a city noted for its towering granite memorials, the only markers indicating the cemeteries’ existence are a few small metal signs that say: “Gardening is not permitted — This Is A Historic Cemetery.”

In 2005, the D.C. Department of Parks and Recreation, which manages Walter Pierce Park, began a terracing project on the park’s northeast slope in hopes of managing soil erosion and improving the ground for community gardening. To determine whether any graves remained in that spot, the city sponsored an archaeological project and brought in a backhoe to dig an exploratory trench.

Enter longtime resident Mary Belcher, who proudly describes herself as a perennial thorn in the city’s side. She knew the site contained a historic cemetery and was alarmed at the excavation by heavy machinery. “You don’t dig in a known cemetery with a backhoe,” she says.

Belcher and a friend sifted through heaps of soil unearthed by the backhoe and found oyster shells and decorative items indicative of grave markers. She complained to D.C. officials, and they agreed to a temporary stop.

The parks department held a meeting with community members to discuss the project. Officials told residents they believed the cemetery was empty, but neighbors and community gardeners responded that they had encountered several exposed human remains over the years. “Every time it rains, it’s a natural archaeological dig,” says Steve Coleman, executive director of the nonprofit Washington Parks and People, which leads cleanup efforts in the park. The city eventually agreed to halt community gardening and postpone the terracing until a more thorough investigation could be completed with the help of Howard University’s anthropology department.

Digging into the past

To lead the research, Belcher tapped Mark Mack, curator of Howard University’s W. Montague Cobb Biological Anthropology Laboratory, who had previously worked with the New York African Burial Ground in Lower Manhattan. The park project would consist of two concurrent investigations: compiling a list of the buried, and conducting a noninvasive surface survey. Belcher and Mack raised $12,000 from community organizations and preservation societies to pay Howard students for their participation.

“The first thing we did was collect all the names we could find from the D.C. archives’ burial records,” Belcher says. “We would go there every day and just pore through the records.”

In the end, the team tallied 8,428 burials, with fewer than 300 of them recorded as being dis­interred and reburied elsewhere. Hundreds — possibly as many as 1,900 — of the bodies actually came from an older African American cemetery that had been at 12th and V streets NW.

There were biographical details, too: names, ages, birthplaces and occupations. About 60 percent of the bodies buried at Mount Pleasant Plains were of children under the age of 5. Most of the adults buried there had moved to Washington immediately after the Civil War. Most had been born in slavery. “Being buried in a cemetery of their choosing would have been part of their newfound freedom,” Belcher says.

The team also traced the family records of the deceased and found that they have about 1 million living descendants. One of those is Dawne Young, a marketing consultant in Montgomery County and a docent at the National Museum of African American History and Culture. She went to a remembrance event in the park last year in which attendees read aloud the names of the buried.

Although she knew her great-great-great-grandmother, Elizabeth Edmonson, was buried there, she had no idea that many other names would be familiar. “When we were rattling off names, I was surprised to hear so many of my relatives,” Young says. “I didn’t know how many were there.” In all, 23 members of the Edmonson family were buried in the cemetery.

The District stopped issuing burial permits for Mount Pleasant Plains Cemetery in 1890, claiming the ground was at capacity. The once bustling cemetery became dormant and unkempt. The land changed hands several times over the next few decades.

Development takes a toll

In 1939, developers who hoped to build apartment buildings hired an under­taker to disinter and rebury the bodies in another cemetery. He located 129 remains and 13 headstones, and the cemetery was deemed clear of human remains.

But efforts to level the ground in 1959 turned up numerous graves and bones, and the city halted construction. Eventually, the developers abandoned the land. The District acquired it in 1982 and named it Community Park West, which later became Walter Pierce Park. The land that made up the cemetery today falls under three different jurisdictions. The majority is in Walter Pierce Park. A thin strip of the northern boundary belongs to the National Zoo, and the western slope abutting Rock Creek Park is National Park Service land.

In 2006, Mack and Howard University students conducted a survey of the grounds. They plotted and photographed gravestones and other grave markers, coffin handles and hardware, ceramic and glass pottery shards, numerous seashells used to decorate the tops of graves — and some human remains. They found several pieces of different skulls, a vertebra, several tibias and tibia fragments, femurs and the corner of a coffin jutting out beneath exposed tree roots on the park’s heavily eroded western slope.

A year later, community gardeners returned to the park and planted crops in the northeast corner. They gardened there for several months, forcing Mack and his crew to resurvey the site.

Belcher eventually succeeded in getting gardening banned. “They know there’s a cemetery, they just don’t [care],” she says.

Park officials also sanctioned the use of a strip of the park’s western edge as a dog run, which infuriated Belcher. “I just really don’t like the idea of dogs pissing on people’s graves,” she says.

In 2010, the National Park Service began a soil erosion mitigation project on the park’s west slope. Belcher and Mack objected, arguing that the exposed coffin and human remains they’d discovered there could be damaged.

Simone Monteleone, a historian with the Park Service who oversees Rock Creek Park, says the work was as noninvasive as possible. Workers didn’t terrace the land, they didn’t dig, and they respectfully covered any remains they found, she says. “We made every effort to protect the remains.”

Belcher, however, says workers carelessly tossed boulders down the slope to fill gullies, rolling over exposed remains in the process. Stakes were driven into the ground, she says, and contractors’ cars and trucks parked on the site. Belcher complained to the city and convinced officials to temporarily halt the work. The project was finally completed after the Park Service agreed to let Mack and two other archaeologists monitor the remaining labor.

On May 11, 2012, Mack was killed in a car accident, and the Walter Pierce Park Archaeological Team lost its “heart and soul,” Belcher says. “He was irreplaceable, really.”

Although the majority of the investigation was complete, a few analyses remained. Mack’s colleagues from the New York African Burial Ground helped finish his work.

Preservation efforts

This year, Washington Parks and People commissioned a ground-penetrating radar study. Jarrod Burks, an archaeologist with Ohio Valley Archaeology, based in Columbus, Ohio, conducted it. He hasn’t filed his final report, but he said in an e-mail that while the ground has been badly disturbed, “[t]here is at least one, or two, areas where I was able to collect some good data on ground that had not been as disturbed, and in these areas I managed to detect what I think are graves.”

Belcher finished the archaeological team’s report this month and submitted it to archaeologist Ruth Trocolli in the D.C. Historic Preservation Office. It will be released to the public at Saturday’s memorial ceremony.

The report claims that thousands of graves containing human remains are still beneath the park and recommends that development be kept to a minimum. It also calls for protecting all skeletal remains, establishing a commemorative space in the park and nominating the site to the National Register of Historic Places.

“A hundred thirty years later, we need to repair this history,” Belcher says.

Trocolli hasn’t reviewed the report yet, but she says she’s convinced that “there’s definitely some human remains.” However, she objects to Belcher’s characterization of the city’s erosion-mediation efforts, arguing they have been necessary to protect both the parkland and the cemetery beneath it.

Belcher’s staunch efforts to preserve the cemetery are occasionally at odds with others who want to see park facilities improve, Trocolli says. “Mary is a tireless advocate for the park, but her vision of the park. One of the aspects of the park is that it’s both a cemetery and a park, and both deserve consideration.”

Nearly everyone agrees on one thing: Some kind of permanent memorial is warranted.

Justin Dunnavant, one of the Howard University students who worked with Mack and currently a graduate student studying anthropology at the University of Florida, says a memorial is essential for commemorating the sacred spaces of people who historically have been denied full equality. “When I pass, I want to know whether my remains will be honored and respected, or if they will be the location of a condo or a dog park.”