Contamination from Philadelphia refinery that exploded could pollute New Jersey groundwater. Here’s how.

The Philadelphia Energy Solutions refinery operations, part of which exploded and burned June 21 in South Philadelphia, has for decades sat atop plumes of underground water lurking beneath the sprawling 1,400-acre site and beyond.

Although the groundwater is contaminated, it is not viewed as a direct threat to the city’s drinking-water supply. Philadelphia pulls its drinking water from the Schuylkill and Delaware Rivers, upstream from the refinery. And no one can withdraw groundwater without city approval.

But could the polluted plumes migrate to New Jersey underground? Christina Simeone posed the question in her detailed look at the PES facility in September for the Kleinman Center for Energy Policy at the University of Pennsylvania. The PES refinery complex sits at the confluence of the Schuylkill and Delaware, and close to where the huge aquifer flows just under the surface.

Simeone’s report was referenced widely after the fire. Now a doctoral student in Colorado, she is the former director of policy and external affairs at Kleinman. She is also a former director of the PennFuture Energy Center for Enterprise and the Environment, and a former official at the state Department of Environmental Protection.

“I think there’s enough here to be asking questions,” Simeone said in a phone interview.

Simeone’s report contained a section on the refinery’s historic impact on the Potomac-Raritan-Magothy underground aquifer system, which holds billions of gallons of fresh water. Known as PRM, the aquifer runs under the refinery complex — and under the Delaware River, eastward into New Jersey. The aquifer’s outcrop — where it is closest to the surface — is at the Delaware River.

The aquifer is a main supply for drinking water in Gloucester and Salem Counties. Gloucester County is directly across the river from the refinery. With increased population growth and development in the counties, withdraws are expected to increase, according to the USGS. The PRM aquifer — composed of upper, middle, and lower aquifers separated by rock or earth — is also a source of drinking water in Camden County.

Though New Jersey has long been concerned with any threats to the aquifer, it has not singled out the Philadelphia refinery.

Larry Hajna, a spokesperson for the New Jersey DEP, said any municipal or private company drawing water for drinking has to apply for permits, test for a range of chemical compounds, and notify the state if any are found. Since the state has not received any such notices, he said, the water is safe to drink.

Hajna notes the region has an extensive history of industrial pollution, making it difficult to trace plumes of contamination to a single source. In addition, the Garden State has its own refineries off the river.

But the South Philly refinery complex clearly is contaminated. It holds two refineries: Girard Point, where the blast and fire occurred, and Point Breeze. Both are close to the Delaware where the aquifer’s outcrop is located.

The polluted plumes underneath the refinery contain hydrocarbons, the result of fossil fuels that have been processed at the site for 150 years. PES has owned the site only since 2012 but is now closing the complex and plans to sell it. Sunoco previously owned the refinery and agreed to spend $207 million on a cleanup that included addressing groundwater.

“There is widespread hydrocarbon contamination of soil and groundwater at the site, including migration outside the property line and potentially into the deep aquifer New Jersey uses as a water source,” Simeone wrote in her report, adding that benzene, lead, the gasoline additive MTBE, toluene, benzo(a)pyrene, and other toxic compounds also pose threats.

“In some areas, contaminants have migrated offsite, and a drinking water aquifer used by the state of New Jersey could potentially be impacted,” Simeone wrote.

Simeone noted a joint 1985 U.S. Geological Survey and New Jersey DEP study that looked at contamination near the aquifer’s outcrop and found spikes in benzene levels in the area of the refinery.

“You can’t say there’s a causal relationship,” Simeone said. “But it raises questions.”

Sunoco’s own monitoring wells detected benzene levels in the groundwater, but the company noted that groundwater throughout Philadelphia is contaminated. The company has launched a website on the cleanup.

The aquifer was called a potential area of interest under an EPA proposal for a cleanup plan of the refinery complex before it caught fire. The site is currently under the complex cleanup process, that is likely to become even more thorny given the fire and potential sale.

The Pennsylvania DEP has been involved with the cleanup since the early 2000s. And, in 2011 the facility entered into a joint DEP and EPA cleanup to satisfy both state and federal corrective measures.

The agencies divided the PES complex into 10 geographic “areas of interest” on land. It created an 11th — the underground plumes.

Summing up all the contamination issues at the plant, which dates to 1866, is difficult because its history is so long and tangled. Sunoco has assumed responsibility for cleanup, at least up until the sale to PES in 2012. Whether the fire has caused additional pollution to groundwater remains unclear.

The June fire occurred in the hydrogen fluoride alkylation unit within the Girard Point fuels processing. The unit uses hydrofluoric acid as a catalyst, and it is one of the most toxic materials handled in the refinery. In its gaseous state, hydrogen fluoride can drift beyond the refinery fence line and imperil the public. No hydrogen fluoride was released during the fire, officials said.

As part of the facility’s closure, the DEP will require “shut down” actions, according to Elizabeth Rementer, a spokesperson for the agency.

Investigators with the U.S. Chemical Safety and Hazard Investigation Board have not yet been able to access the site where the blast occurred because of safety concerns, halting any progress toward finding out more about the fire’s cause and possible further contamination.

But the refinery long has been identified as a threat to the aquifer. In 2001, the USGS was concerned enough that it modeled how water might flow into the aquifer, noting: “Because of the development in the area, the quality of water in the PRM [aquifer] has been degraded. Some degradation in the upper part of the aquifer is the result of numerous hydrocarbon plumes."

The USGS report cited “multiple localized NAPL hydrocarbon plumes floating on the water-table surface in the south Philadelphia area.”

The report mentioned the refinery as one of several potential sources of polluted plumes.