Before sunrise on a June morning in 2019, a section of pipe nearly five decades old ruptured at the Philadelphia Energy Solutions refinery, spewing a cloud of flammable vapor that hung to the ground like a spectral fog.

Within minutes, according to a surveillance video, a series of explosions in the South Philadelphia refinery’s alkylation unit rained huge pieces of shrapnel across the refinery and released 5,239 pounds of hydrofluoric acid (HF), a chemical so toxic that worker-safety advocates have called for its banishment from use in refining.

No injuries were linked to the release. But the U.S. Chemical Safety Board, in a preliminary report four months later, noted that the Philadelphia accident was the third near-miss in recent years at a refinery that used HF to produce an octane-boosting additive called alkylate.

“The board remains concerned that the next time there is a major explosion at a refinery that uses HF for alkylation, workers and those living nearby will not be so lucky,” said Kristen Kulinowski, the CSB’s interim chief executive at the time.

CSB staff members, who spoke on the condition of anonymity because they were not authorized to speak, said that an early 2020 draft of the report on the accident urged the U.S. Environmental Protection Agency to wield its authority and phase out the use of HF in refineries. That would have represented a major escalation of alarm from the independent agency, modeled on the much bigger National Transportation Safety Board, whose recommendations can drive policy changes and put industry on notice about systemic hazards.

But the final report on the Philadelphia accident has yet to be released. It’s among 19 open investigations that have piled up at a weakened and understaffed agency. The Trump administration, after failing to convince Congress to eliminate the CSB, allowed all but one seat on the agency’s five-member board to go vacant.

“Strong safety recommendations from CSB reports can help save lives, but only if they are issued in a timely fashion,” said Rick Engler, a New Jersey worker-safety advocate who served on the board from 2015 until 2020. He said the backlog of investigations is unprecedented in the agency’s 23-year history.

» READ MORE: S. Philly refinery blast released 5,000 pounds of a deadly chemical, federal investigators say (from October 2019)

“Former President Trump spent four years undermining the Chemical Safety Board and left office with only one member remaining on this five-person board,” U.S. Sen. Tom Carper (D., Del.), chairman of the Senate Committee on Environment and Public Works, which oversees the CSB, said in a statement. “Without a quorum, the board is currently hampered in its ability to effectively do its job.”

Carper, an ally of President Joe Biden’s, said he looks forward to working with the administration to fill the CSB vacancies soon “so that the board can get back to its mission of keeping communities and workers safe.” The White House press office did not respond to questions about Biden’s plans for the board.

But the wheels of Congress move slowly, and even if the administration nominates board members quickly, it typically takes many months to vet and approve appointments, especially for an agency as controversial as CSB, which the Trump administration complained had “frustrated both regulators and industry.”

The CSB has limped along for several years, buffeted by scandals and leadership disputes that predated Donald Trump’s 2016 election. The EPA’s Office of Inspector General, in a 2018 report, said the Trump administration’s efforts to eliminate the CSB impeded its ability to hire and retain staff. The board put some of its problems behind it after Congress renewed funding with “broad bipartisan support,” the inspector general said last July.

But the inspector general recommended filling the four vacant board seats quickly. “Having only one member impairs the function of the CSB, as all functions rest with that one member,” he said.

In an emailed response to questions from the Center for Public Integrity and The Inquirer, CSB spokeswoman Hillary Cohen wrote that the board “is working on its 19 open investigations and continues to deploy to high consequence incidents across the country.” It recently hired two investigators and will add more throughout the year, she wrote. The CSB has 12 investigators, including supervisors. At one point it had 20.

» READ MORE: Bankrupt Philadelphia Energy Solutions blames ‘mislabeled’ pipe for big blast that led to refinery’s closure

But worker-safety advocates and CSB staff members worry that under the leadership of a single board member — chairman Katherine Lemos, a Trump appointee — the agency’s work has suffered. The current draft of the Philadelphia report, awaiting approval by Lemos, no longer contains the recommendation to phase out HF, the staff members say.

“That indicates to me the potential for undue influence from the industry,” said Mike Wright, director of health, safety and environment for the United Steelworkers, a union that represents more than 30,000 workers at refineries, petrochemical plants, and other oil and gas facilities.

Lemos declined to be interviewed for this article. “The CSB does not comment on draft reports in that it is the board that does its final review and is responsible for voting on the recommendations,” Cohen wrote in her email.

Industry representatives denied influencing the recommendation on HF. The American Fuel and Petrochemical Manufacturers, a refinery trade group, acknowledged that it does engage with the board over proposed recommendations, but said the CSB has not reached out to it about the Philadelphia report. “AFPM doesn’t have visibility into CSB’s report writing and revision process and hasn’t seen any report drafts,” it said in a statement.

The American Petroleum Institute said that it had no insight into the CSB’s decision-making, but that refiners adhere to strict operational standards designed to mitigate risk and assure safe operations.

“The natural gas and oil industry’s top priority is protecting the health and safety of its employees, communities in which it does business, and the environment,” API Refining Program manager Andrew Broadbent said in an email.

Accidents and close calls

While refinery workers are at greatest risk from an HF release — a worker at a Valero refinery in Memphis died of exposure in 2012 — if uncontained the acid can form a ground-hugging, fast-moving cloud that can travel several miles, sickening and killing those in its path.

The use of HF at refineries has been the target of safety advocates and community activists for more than three decades, since a tank containing the acid at a Marathon Petroleum refinery in Texas City, Texas, ruptured in 1987, forcing the evacuation of 4,000 people and sending more than 1,000 to the hospital with skin, eye, nose, throat and lung irritation. Tens of thousands of pounds of HF gushed out over 44 hours. The jet went straight up; had it gone sideways, people living nearby might have died.

A decision to phase out HF could have a profound impact on the refining industry. Industry representatives say such a ban could force the closure of some plants, drive up fuel prices, and increase the nation’s reliance on imported fuel.

They say HF has been used safely for decades and cannot be easily or economically replaced with the most common alternative technology, which uses sulfuric acid. A United Steelworkers report in 2013 identified two other options — a solid acid catalyst and an ionic liquid alkylation process — that would virtually eliminate the risk. The industry says those options are not commercially viable.

» READ MORE: How a control room ‘hero’ saved Philly from a catastrophe during refinery fire (from June 2019)

Valero, in a 2019 presentation to Southern California regulators who were considering an HF ban, played down the threat to the public: “In over 50 years of HF alkylation operations, there has never been an off-site fatality.”

That’s true. But near-misses at a Husky Energy refinery in Superior, Wis., in 2018 and an ExxonMobil refinery in Torrance, Calif., in 2015 highlighted the potential for mass casualties.

Those close calls moved the CSB’s Kulinowski to send a letter to Andrew Wheeler, then administrator of the EPA, in April 2019, asking the agency to update a 1993 study of HF to determine whether refineries’ risk-management plans were “sufficient to prevent catastrophic releases” and whether there were safer, commercially viable alternatives.

The reply came more than five months later. The EPA “does not believe that updating the study would accomplish either of the objectives set out in your letter,” wrote then-Assistant Administrator Peter Wright.

The EPA, which has new leadership under Biden, did not respond to a request for comment.

After Torrance, the oil industry, teaming up with some labor representatives, successfully beat back efforts to ban HF at the ExxonMobil refinery — now owned by PBF Energy — and another in the Wilmington section of Los Angeles owned by Valero. Industry consultants said it would cost the companies $1.8 billion collectively to replace their HF units, which would likely lead to the closure of the refineries and shortages of specially formulated California gasoline.

The companies agreed to install additional protective measures to reduce the risk of an HF release and are using a modified form of the acid that is supposed to lessen its toxicity and hinder its cloud-forming ability.

But some are still pressing for a ban. Steven Goldsmith, president of the Torrance Refinery Action Alliance, a citizens group, said modified HF reduces the risk “so little it’s meaningless.” Safer ionic liquid alkylation is being used in several Chinese refineries, he said, and two U.S. refineries — in Utah and Oklahoma — are being converted to that technology from HF alkylation.

Research conducted by the alliance shows that nearly five million people live within six miles of the 41 U.S. refineries that use HF, Goldsmith said. These residents are disproportionately low-income and people of color, he said.

Mike Wright, of the Steelworkers, said the union has warned industry officials, “All it would take is one serious accident with HF that kills a significant number of people offsite and you’ll never get permitted to build a refinery in this country again, and localities will do everything they can to drive you out.’”

In Philadelphia, there was a public backlash following the 2019 refinery explosion. Mayor Jim Kenney and the City Council last year approved a ban on the use of HF at any refinery, a symbolic gesture by that time because Philadelphia Energy Solutions declared bankruptcy and closed after the accident, and the 1,300-acre property was sold to a developer that promised not to reopen the refinery.

A second refinery in the Philadelphia area that uses HF, the PBF Paulsboro refinery in Gloucester County, closed many of its operating units at the end of 2020 in response to a long-term slowdown in fuel demand, accelerated by the COVID-19 pandemic. The HF alkylation unit was among those retired.

The remaining facility in the region that uses HF is the Monroe Energy refinery in Trainer, Pa., owned by Delta Air Lines.

Jim Morris is executive editor at the Center for Public Integrity, a nonprofit, nonpartisan investigative news organization in Washington.