The dangerous task of disposing of a toxic chemical at the Philadelphia Energy Solutions refinery could put workers and the surrounding community at risk, according to city officials.
Hydrofluoric acid is integral to the creation of high-octane gasoline. It’s used at about 48 alkylation units in the United States — including the South Philadelphia refinery, where an explosion in June destroyed the unit and led to the closure and bankruptcy of the financially troubled plant.
But until the 33,000 gallons of hydrofluoric acid remaining at the site are treated and neutralized, the incident area remains unsafe and off-limits to anyone not wearing protective clothing.
Philadelphia Fire Commissioner Adam Thiel said firefighters with the hazardous-materials unit continue to remain at the site 24/7.
“Rest assured we will be down there sharing this risk with the community and doing our best to stand between the community and danger,” Thiel said, “and we will continue to do that.”
Hydrofluoric acid is one of the most dangerous industrial chemicals in use.
“It’s a very special acid,” said May Nyman, professor of chemistry at Oregon State University. “It’s important for certain applications. But it’s also very dangerous.”
At room temperature, HF is a gas, but for industrial use, it is dissolved into a liquid solution. Swallowing just a small amount of HF or getting small splashes on the skin can be fatal, according to the Centers for Disease Control. The acid molecules are very small and can easily penetrate the skin and get directly into bones, where the acid reacts with calcium and effectively dissolves the bones.
In the gaseous state, the CDC says, low levels of HF can irritate the eyes, nose and respiratory tract. Breathing it at high levels “can cause death from an irregular heartbeat or fluid buildup in the lungs.”
Neutralizing the HF brings those risks to the fore.
Neutralizing an acid involves adding a base — the sort of lab process, known as titration, that many people do in high school and that results in a neutral solution of water and salt. But such a reaction can be dramatic and dangerous. The erupting spectacle of vinegar and baking soda is a low-level example of what can happen over the course of such a process.
In the case of HF, the biggest danger is the extreme heat produced during the reaction — and the risks that come with that. As the solution heats up, some of the dissolved HF gas can become airborne. The risk at the refinery is compounded by the fact that there is so much HF to neutralize.
“The volume is certainly a problem,” May said. “If we’re concerned about the heat that is released when you neutralize it, it scales with the volume.”
That would put workers and the community at risk, so Thiel said the process needs to be handled carefully.
“It’s brutal conditions,” Thiel said. “The people that are doing this have to work in chemical protective clothing out in the heat, so it’s not something that can happen fast to do it right.”
The fire commissioner said authorities are still figuring out the best way to proceed while keeping worker and community safety in mind.
“There’s a term in our business: slow is smooth, smooth is fast,” he said. “This is one of those situations.”
May said one way to keep the solution cool is to dilute it with water, which absorbs heat and prevents the temperature from going up as high or as fast.
But that only works if there is enough space in the tank to add more water, and it’s unclear whether that’s the case at PES. If it isn’t, May suspects they will add a base — something like sodium hydroxide or calcium hydroxide (also known as lime) — bit by bit, over an extended period.
“This is a complex, fluid and dynamic situation,” said Thiel. “The reason we have not placed the incident under control is because there is significant risk on the site and significant hazards. We have a lot of people down there 24/7, 365. It’s a very long process.”
Thiel said that the neutralization process should commence in a matter of days, but that the site will not be put under control until all of the hydrofluoric acid is treated and neutralized, at which point it can be discharged to the refinery’s dedicated wastewater treatment plant.
Meanwhile, the Fire Department, along with officials from the Office of Emergency Management and other state and federal agencies, have been meeting daily to discuss plans for an accidental release.
“There are daily plans and weekly plans and contingency plans and contingency plans for the contingency plans,” Thiel said. “This is what we do, and we have been doing it literally 24/7, 365 since June 21, and we will continue to do it until the work is done.”
As part of the refinery’s risk management plan, which Philadelphia Energy Solutions is required to submit to the EPA, a worst-case scenario for release of the toxic chemical at PES would involve 143,262 pounds — or approximately 13,000 gallons — of HF over 10 minutes. The vapor cloud could travel for more than seven miles and potentially affect 1,098,799 people, including those in schools, homes, hospitals, prisons, playgrounds, parks, and a wildlife sanctuary.
The chemical is also used at the Monroe Energy plant in Trainer, Delaware County, and at PBF’s Paulsboro refinery in Paulsboro, N.J.
WHYY’s Catalina Jaramillo contributed reporting.