Crews examine possible chemical contamination at Bartram's Garden in Philadelphia

Could one of the city's most treasured trails be the site of a chemical contamination?

Crews are working to find out exactly what is in a mysterious liquid that flowed across a bike trail in Bartram's Garden.

For now, that part of the trail is closed. It's a concern for the oldest surviving botanic garden in North America.

On Thursday, Action News spotted workers from the Pennsylvania Department of Environmental Protection and Philadelphia Water Department on the scene examining green liquid at a property adjacent to Bartram's Garden.

The suspected "leak" onto a public bike path along the Schuylkill River likely came from a former petroleum tank farm that's next to Bartram's Garden. That land is privately owned.

A regular visitor notified Bartram's Garden about the possible contamination in April, but Councilmember Jamie Gauthier says she wasn't notified until recently.

"We were notified Monday by a constituent," she said. "Unthinkably there was no warning to the surrounding community."

According to information posted on the Bartram's Garden website , groundwater and soil samples show the presence of a known carcinogen.

The Pennsylvania Department of Environmental Protection, which is now working with the landowner, said in a statement to Action News, "Visitors walking, running, or riding a bike on the trail through the area are at very low risk for exposure."

The Philadelphia Water Department says there's no risk to the city's drinking water.

"The possible contamination is not near the city's water infrastructure," said Gauthier of updates she's received on the investigation.

The mayor's office released a statement to Action News that reads in part, "City officials are working closely with state environmental partners to assess the situation and ensure the public health and safety of the surrounding area."

That statement goes on to say that the Philadelphia Fire Department's hazmat unit didn't find any toxic runoff or threats to air quality.

For now, though, part of the Bartram's Mile Trail will remain closed as crews investigate the potential contamination.

"If necessary (the landowners will) come up with a remediation plan with Bartram's garden," said Gauthier. "So hopefully we can make the site safe again and people won't have to worry about any environmental risk or threat there."

Other parts of the trails at Bartram's Garden are still open. Pennsylvania's Department of Environmental Protection will test the water runoff around the affected trail. When Bartram's Garden gets the results, they'll post them on their website.