The alarm sounded around 4 a.m. and the plant dispatcher began broadcasting across every channel at the sprawling Philadelphia Energy Solutions refinery in South Philadelphia. There was a leak. In Unit 433.

“As soon as they said Unit 433, we’re coming out of our chairs,” said an operator at the refinery who was working that shift. “That’s the unit you don’t want to leak.”

The reason: 433 uses highly toxic hydrofluoric acid. A major accidental release could suddenly send a dangerous cloud of hydrogen fluoride drifting over South Philadelphia and other heavily populated neighborhoods.

“He was still transmitting the script when the first explosion rattled our blockhouse," recalled the operator, who asked not to be named. “You heard the tone of his voice change and he stumbled and then he changed it to a report of a fire, instead of a leak. It was like a fireball and there was smoke and vapor and horrendous noises and debris.”

At 4:05 a.m., the Philadelphia Fire Department struck the first alarm.

That wouldn’t be the only explosion at the refinery that morning.

In the end, it was the most serious refinery accident here in decades. The June 21 explosion and fire caused no deaths but had the potential to have been catastrophic. In a bitter irony, the only fatality to result from the fire appears to be that of the facility itself, which is now set for permanent closure. What follows is a reconstruction of that event as experienced by refinery workers on the scene that morning as well as firefighters and city officials charged with responding to it.

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Ryan O’Callaghan, who leads about 640 workers as president of United Steelworkers Local 10-1, was asleep at his Ridley Township home when he received an ominous text from the refinery’s managers at 4:06 a.m. alerting him to an emergency at the plant. It mentioned a fire and the wind direction. Then, he received a call. It was from a union official on the emergency response team. The message was brusque: “Get in here.”

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Deputy Fire Commissioner Craig Murphy was asleep in South Philadelphia when he was roused by the first explosion, but not recognizing its significance, he drifted back to sleep.

Fifteen minutes later, at about 4:15 a.m., fire communications called.

“I’m waking from a dead sleep,” Murphy said of the phone call. “He said there was an explosion.”

Murphy went out to his truck, grabbed his radio, and headed back to the house and started listening in to the firefighters who were already responding.

At 4:20 a.m., the second alarm was struck.

“Somewhere around there, I heard a second boom,” Murphy said.

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That explosion, at 4:22 a.m., was captured live by news cameras. It was so intense that it was picked up by orbiting weather satellites. The blast sent those in and around the refinery reeling.

It was still an hour till sunrise, yet, “It looked like somebody turned a light switch on in the sky,” said a first responder who was racing to the scene.

Sean Mack, a battalion commander who works out of the Engine 69 Firehouse in Southwest Philadelphia, was first in — and in command. With the first alarm, Mack led four engines and four ladder trucks across the Platt Bridge, along with medics and Hazmat technicians. The run took four minutes.

Mack arrived before the second blast sent a wall of heat that blistered the paint on his command Chevy SUV. Mack declined comment for this article; other firefighters said he was shielded by a fire vehicle.

“He was lucky to be behind it,” a firefighter said.

A refinery worker on the scene said the force of the second blast staggered him.

“I felt the heat on my face,” he said, “but I was far enough away that I’m talking to you now.”

In the backs of the minds of some firefighters that morning was Aug. 17, 1975.

A 12-alarm fire that day at the Gulf refinery complex was one of the worst disasters in the fire department’s history. An overfilled 80,000-gallon oil storage tank exploded. Eight firefighters were killed and 14 were injured.

Fire scene at the Gulf refinery complex in August 1975.
File photo
Fire scene at the Gulf refinery complex in August 1975.

Five people were injured in the PES fire, none seriously. But workers inside the refinery had initially assumed there were fatalities.

“For 20 minutes, we were trying to figure out how many people we were burying,” a worker said. “When they came over the radio saying everyone was accounted for I was in disbelief. After what I just witnessed with my own eyes, there was no way we didn’t have fatalities. Then, after that, I said, ‘Get your resumé polished.’ ”

He was right: No one was killed, but, as it was made plain days later in a company announcement, their jobs were going up in smoke along with the liquefied petroleum gas that was burning.

At 4:24 a.m., two minutes after the second explosion, the Philadelphia Fire Department struck a third alarm — sending, in all, about 51 trucks and 120 people to the site. City firefighters assisted the refinery’s own fire brigade, and brigades from at least three other refineries — Monroe Energy in Trainer, Sunoco in Marcus Hook, and PBF Energy in Paulsboro — arrived and waited in standby mode.

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In the middle of the chaos, an operator in the central control room, located in the shadow of the Passyunk Avenue Bridge far from Unit 433, took quick action and shuttled the hydrofluoric acid to a separate container, according to O’Callaghan, the steelworkers president. The industry term for that is “rapid deinventory.”

“The equipment that was installed to save the acid worked. She did a great job,” O’Callaghan said of the operator, who declined to be interviewed. “She saw it come up and she took action and followed her training.”

A refinery worker on the scene who wasn’t authorized to publicly discuss the matter offered this assessment:

“She’s a f-ing hero. Whatever she did up there,” he said. “When you’re ‘on the board’ as we call it, your alarm screen looks like a slot machine, all the alarms are going off.” He said she may have “saved the city, really."

Had the blast released a potentially lethal cloud of hydrogen fluoride, within 10 minutes it could have traveled as far as seven miles. More than a million people live within that area.

“Philadelphia and surrounding communities appear to have narrowly dodged a catastrophe this morning,” Joseph Otis Minott, executive director of the Clean Air Council, said in a letter calling for the U.S. Chemical Safety and Hazard Investigation Board to investigate. That investigation is now underway.

The incident has resharpened the focus on the use of hydrofluoric acid in refineries. The steelworkers have long called for the development and use of new, safer technologies.

“We’d like to see the whole industry move to something that is intrinsically safer,” said Mike Wright, director of health, safety, and environment for United Steelworkers International in Pittsburgh, where officials were tracking developments in the fire.

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At 5 a.m., Mayor Jim Kenney received a phone call from a PES official alerting him of the fire. The city’s Office of Emergency Management tweeted at 5:41 a.m. that residents east of the refinery at 3100 W. Passyunk Ave. should shelter in place. A half-hour later, the shelter-in-place notice was narrowed to 26th Street to the east, Schuylkill Expressway to the north, I-95 to the south, and 22nd Street to the east “due to smoke and apparatus in the area.”

On the scene, firefighters had several tasks to tackle at once — douse the flames, stop any spread of the fire, and find the right valves to cut off any ongoing source of fuel. In the end, there was no magic to putting out the fire. All it took, Fire Commissioner Adam Thiel said wryly, was “copious amounts of water.”

Thiel acknowledged that a fire involving fuel and nearby chemicals posed special problems. When a house burns, he said, “everything is about getting inside that building fast, finding the fire, putting the fire out, locating and rescuing anybody who’s inside.”

In contrast, he said, “on a Hazmat incident we sort of go to the perimeter and then work our way in carefully.”

Murphy, the deputy commissioner, agreed. In a structure fire, he said, "You have to get into the place and start putting the fire out. But in a situation like this there are so many variables and things that can go wrong, we would never fight it from the inside.”

Philadelphia Mayor Jim Kenney leaves the Fire Department headquarters on Spring Garden Street after a meeting with Fire Department officials about the refinery fire Friday, June 21, 2019.
MARGO REED / For the Inquirer
Philadelphia Mayor Jim Kenney leaves the Fire Department headquarters on Spring Garden Street after a meeting with Fire Department officials about the refinery fire Friday, June 21, 2019.

The order to shelter in place was lifted at 7:07 a.m. Kenney spokesperson Deana Gamble said Unified Command — the fire department and PES — had made the decision “because it was confident that HF was not involved in the fire based on safety protocols that were executed successfully.”

City officials got word via a 7:45 a.m. emailed update that all PES employees had been accounted for and that there were no “significant” injuries.

At 8:30 a.m., Mayor Kenney huddled with city officials at the high-tech Emergency Operations Center, in the basement of the Fire Department headquarters at Third and Spring Garden Streets. There, Kenney presided over a large conference with a dozen or more people that included Mark Smith, chief executive for Philadelphia Energy Solutions, Fire Commissioner Thiel; and Kenney’s chief of staff, Jim Engler.

Another participant, Tumar Alexander, the city’s first deputy managing director, said city officials questioned PES executives about a June 10 fire at the refinery. Participants pooled information and Kenney announced plans to create a task force to investigate the accident and recommend any needed reforms.

Shortly after that 30-minute session wrapped up, Kenney and Alexander dialed into a second session to brief elected officials representing South Philadelphia. While PES had already reached out to them through a “stakeholder” alert protocol, they wanted to hear from the city as well, Alexander said Friday.

At 9:37 a.m., the Philadelphia Health Department said Air Management Services was on-scene immediately and took air samples at the refinery and in the surrounding community and found no ambient carbon monoxide, hydrocarbons (combustibles), or hydrogen sulfides: “The Health Department has no findings that would point to any immediate danger in the surrounding community at this time, and the City is NOT recommending evacuation or shelter-in-place.”

Twenty minutes later, PES issued a media update saying “there were three separate explosions on the unit. The unit impacted was one of our alkylation units. We have not determined the product that was burning, but we believe it was mostly propane.”

There was no mention of hydrogen fluoride, but the refinery has two alkylation units, including one at Girard Point that uses the hydrofluoric acid. Some outsiders connected the dots.

PES announced that as of 2:43 p.m. a “very small fire remains.” The controlled fire continued to burn as crews sought to isolate the remaining line.

It was not until Sunday, after an Inquirer story outlining the risk of hydrofluoric acid that PES first publicly mentioned its presence. In a 5:31 p.m. statement Sunday, June 23, the company said there was no detectable leak of hydrogen fluoride:

"We can confirm that the fire at the alkylation unit has been extinguished. PES and a third party continue to monitor the air quality inside the facility each hour, with all readings including HF remaining at normal levels.”

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For the more than 1,000 PES workers, the looming shutdown will put an end not only to jobs, but to a way of life.

“Everybody is still in kind of a state of shock and wondering what their future holds,” said O’Callaghan, the union president. “We’re at the refinery all the time. It’s a 24/7 operation. We’re there holidays and weekends 10 and 12 hour shifts. People miss family events, BBQs, baptisms, weddings. A whole culture is getting wiped away, not the just the jobs.”

A refinery operator who was working the morning of the fire said it was particularly difficult to accept that they would all lose their jobs, given how well they responded to prevent a catastrophe.

“No good deed goes unpunished,” he said.

Staff writers Andrew Maykuth, Jessica Calefati, Claudia Vargas, Laura McCrystal, and Dylan Purcell contributed to this article.