A study released Thursday by Mobil Oil Corp. has concluded that continued use of acutely toxic hydrofluoric acid at the Torrance refinery poses almost no risk to the public.
The comprehensive risk assessment prepared for the city of Torrance by a team of consultants concluded that there is less than a 1% chance per year of a single death occurring in the community from use of the lethal acid.
Expressed another way, the study said the overall risk posed by hydrofluoric acid--which is used to boost the octane of unleaded gasoline--is 1.21 fatalities per 100 years. By contrast, an average of 15 people die each year in automobile accidents in Torrance, the study said.
“It’s certainly not worth losing sleep over,” Mobil refinery manager Wyman D. Robb told reporters. “The risk is reasonable. . . . I would hope the public would be reassured that Mobil is doing everything we can to minimize the risk.”
But Torrance City Councilman Dan Walker, author of a proposed ballot initiative aimed at forcing Mobil to stop using hydrofluoric acid in the city, immediately dismissed the consultants’ findings.
“When Mobil says that Mobil’s plant is safe, that has . . . no credibility,” Walker said in an interview. “Of course it says not to worry.”
Walker vowed to go forward with his initiative, saying safety equipment is susceptible to human error. “Machines break down, computers malfunction, people malfunction. You have a hazard that is too large for this community.”
And he criticized those who minimize the risk. “I don’t see the plant manager living across the street from the refinery or having his family there,” he said.
An excess of hydrofluoric acid in a unit at the Torrance refinery caused a thunderous explosion Nov. 24, 1987, and sparked a spectacular fire that burned for two days. Concern about use of the chemical has grown in the aftermath of the blast and a series of smaller explosions, fires and accidents in other parts of the refinery.
Most other refineries in the South Bay use less-toxic sulfuric acid as a catalyst to boost octane. Mobil has estimated that it would cost $100 million to convert the Torrance facility to sulfuric acid. Robb said Thursday that the company has spent $3 million on studies to see if some other catalyst could be used.
Requested by City
The $275,000 risk management and prevention program was produced by Technica Inc. and Stone & Webster Environmental Services. The study, paid for by Mobil, was requested a year ago by the Torrance Fire Department under provisions of a state law governing acutely toxic chemicals.
The Torrance City Council will decide next week whether to hire a San Diego-based consultant to determine the adequacy of Mobil’s risk assessment. Additional work may be required if the city finds that the study is flawed.
The study contains 19 pages of recommendations for improving safety systems to minimize the risk of an accident involving hydrofluoric acid, which can produce a ground-hugging vapor cloud that, in sufficient quantities, is deadly to people exposed within five miles downwind.
Robb said the company will follow the report’s recommendations.
“Even though the risk is relatively low,” Robb said, “Mobil is not happy with any risk.”
The improvements include installation by 1991 of a $6-million acid evacuation system that would drain the lethal chemical to a storage tank in an emergency. Robb said the system would “substantially lessen risk of a large release impacting on the community.”
Other improvements will include better training, safety equipment and alarm systems. Altogether, the work will slash the danger to 0.15 fatalities per 100 years, the study said. (Those figures are for the general public and do not include the risk to Mobil employees.)
Robb said the oil industry was surprised by results of tests conducted in the Nevada desert in 1986 and 1987. The tests found that hydrofluoric acid was more dangerous than previously thought because when released it forms a heavy vapor that does not disperse readily.
He said he has contacted Torrance Fire Chief Scott Adams about preparing emergency plans in the event of an accident involving release of the acid.
“The risks are very, very low,” Robb said. “Nevertheless, you want to be ready if something does happen. . . . We should think about what are the best things to do if there is a problem.”
Mobil did not release data on more than 700 accident scenarios that the consultants studied, all involving releases of various amounts of hydrofluoric acid. Krishna S. Mudan, vice president of Technica Inc., said the consultants analyzed the impact of different weather, wind speeds and wind direction.
Robb said that releasing maps showing hypothetical vapor plumes over residential areas would scare people.
The consultants acknowledged that they did not conduct studies to predict what would happen in the event of a major earthquake. Robb said the alkylation unit where hydrofluoric acid is used was built to Torrance building codes and therefore such a study was not required.
Robert W. Myers, environmental program manager for Stone & Webster Environmental Services, the other firm that worked on the Mobil study, said the hydrofluoric acid alkylation unit is in excellent condition after being largely rebuilt in 1987 and 1988.
Times staff writer George Stein contributed to this report.