Use of sulfuric acid instead of hydrofluoric acid at the Mobil Oil Corp. refinery in Torrance could pose less danger to area residents in the event of an accident, according to a preliminary report prepared by the Torrance city staff.
But it also would mean a substantial increase in truck traffic and hazardous-waste disposal problems, the report says.
The report, requested by City Council members in the wake of a Nov. 24 explosion and fire at the Mobil refinery, suggests that "while both chemicals are potentially hazardous when used improperly, it is thought that hydrofluoric acid is much more dangerous."
When hydrofluoric acid comes into contact with air, it turns into lethal hydrogen fluoride gas.
The city staff's suggested that the council may want to consider hiring an outside consultant to assess the risks associated with continued use of hydrofluoric acid at the refinery as a catalyst to boost the octane of gasoline. Most other refineries in the South Bay use sulfuric acid.
Mobil announced in mid-December that the explosion was caused by an excess amount of hydrofluoric acid in a refinery unit that produces gasoline.
Four people were hurt in the explosion, but the tiny amount of hydrogen fluoride gas that was emitted into the atmosphere was not considered dangerous, investigators said.
After investigating the Mobil explosion, the South Coast Air Quality Management District staff called for the formation of a high-level, multiagency task force to examine use of lethal chemical at refineries and industrial plants throughout the Los Angeles metropolitan area.
The Torrance City Council endorsed the concept of a task force late Tuesday night. Mayor Katy Geissert told her colleagues the task force would be "a very useful source of information for us" and Torrance should seek representation on it.
The city's staff report contains an extensive discussion about the danger posed by use of hydrofluoric acid at the refinery and suggests that a change to sulfuric acid might be safer in the event of an accident.
The report was presented to council members after published reports said the AQMD staff saw the possibility of a "significant release" of hydrogen fluoride gas at facilities that use the chemical.
Six facilities in the South Coast Air Basin handle or store hydrofluoric acid in significant quantities. In addition to the Mobil refinery, they are Allied Corp. in El Segundo, Union Pacific Resources in Wilmington. Powerine Co. and Golden West Refining Co. of Santa Fe Springs and Jones Co. of South Los Angeles.
The AQMD staff said that a significant release of the gas, caused by employee error, an earthquake, sabotage or some other scenario, could pose an "extreme and immediate health hazard to exposed citizens."
"While the likelihood of a major release is remote, the consequences may be so great as to warrant regulations to direct industry to phase out its use or substitute processes with lesser environmental hazards," the AQMD said.
The AQMD board will meet Friday in El Monte to consider their staff's recommendation that the district "acknowledge the potential for a significant hydrogen fluoride release and the associated public health risk" and establish a task force to study transportation, storage and use of the chemical.
The Torrance staff report suggests said that while sulfuric acid would be less dangerous in an accident, the refinery would have to use a far greater quantity of it. It would take 1,563 truck trips a year to deliver the sulfuric acid to the refinery, instead of 21 truck trips annually to transport the hydrofluoric acid, according to estimates supplied by Mobil.
In addition to truck traffic, the city report said that use of sulfuric acid could pose hazardous waste disposal problems. And conversion to sulfuric acid would require rebuilding parts of the refinery, which converts California crude oil to gasoline, diesel and jet fuel, and other petroleum products.
After the council meeting, Thomas Gregory, Mobil's manager of safety and training, said four of the company's five U. S. refineries use hydrofluoric acid in the refining process. Mobil's Beaumont, Tex., refinery, which is bigger than the Torrance facility, uses sulfuric acid.