Oil slick spreads on the Delaware River near the old Festival Pier in Philly

A multihued sheen emerged this week on the Delaware River in Philadelphia near the former Festival Pier, likely from oil that got into a city-owned combined sewer overflow pipe located along the riverbank.

Cleanup is underway.

“The Water Department’s Industrial Waste Unit responded and began an investigation that is ongoing,” department spokesperson Brian Rademaekers said in an emailed statement. “A local sewer outfall in the area has been identified as a possible source.”

The city’s Office of Emergency Management received a report of the sheen on Tuesday, Rademaekers said.

The city’s Baxter drinking-water treatment plant, 11 miles upstream in Northeast Philly, is monitoring the sheen to ensure it does not harm drinking water, he said. The city pulls its drinking water from the river at the plant.

Jamar Thrasher, a spokesperson for the Pennsylvania Department of Environmental Protection, said that oil trapped in part of the storm system got released when a city contractor was replacing and extending an old wooden pipe, but that the situation “is now controlled.”

Because of its age, the city has what’s known as a combined sewer system, now viewed as an antiquated method of collecting both storm water and wastewater in single pipes. During dry weather, sewage flows to treatment plants via the pipes. However, the plants are forced to release untreated water when they reach capacity during a storm. The overflow releases a mix of untreated sewage and storm water into waterways.

It is unclear whether there was an overflow, or how the oil got in the pipes. Only about a fifth of an inch of rain was officially recorded by the National Weather Service between Sunday and Monday, though pockets of heavy rain did appear, and the Phillies game was delayed Monday night for a passing storm.

Regardless, the combined overflow is near the Festival Pier on the 500 block of North Christopher Columbus Boulevard at Spring Garden Street in Northern Liberties. The pier was the longtime home of the Roots Picnic but closed as a venue in 2019 and is undergoing remediation for development.

The mixed-use project is a partnership between the Delaware River Waterfront Corp. (DRWC) and JAG and Haverford Properties. Plans include housing, retail, and dining just off the Delaware River Trail. The DRWC is a nonprofit organized to design and develop the city’s waterfront between Oregon and Allegheny Avenues.

The site is on a list of the Pennsylvania Department of Environmental Protection’s brownfields and must be cleaned up before redevelopment. It is contaminated by polycyclic aromatic hydrocarbons (PAHs), metals, volatile organic compounds, and arsenic, according to DEP documents. PAHs are a class of chemicals that occur naturally in coal, crude oil, and gasoline. VOCs are organic chemical compounds used to make various products and can be found indoors and outdoors and considered an air pollutant.

Nicole PalouxI, a spokesperson for the DRWC, said there was no connection between a cleanup of the site and the spill.

Julie Slavet, executive director of the Tookany/Tacony-Frankford Watershed Partnership, said she was “exceedingly disturbed” by the sheen, which might reinforce a negative review of the river, which is much cleaner than it was decades ago.

“Bringing people close to the river is a valuable educational and stewardship opportunity that must be based on rigorous environmental assessment and remediation,” she said. “That’s a critical responsibility.”