Exposure to hydrofluoric acid can cause serious injury or death, and the chemical has posed a threat since an explosion and fire ripped through the refinery in June.

Those with private wells close to bases where PFAS chemicals were used have received bottled water. But some places are too far away for the contamination to be the direct result of training exercises, and too far away to have been tested by the Environmental Protection Agency.

The explosion and fire took a day and a half to extinguish and destroyed the unit that turned crude oil into gasoline. Four employees were hurt.

Documents indicate Sunoco has a new maximum operating pressure for the line, which is under construction. An engineer who conducted a risk assessment of the Mariner East project said a higher pressure increases risk.