Adviser Backs Refinery’s Use of Altered Chemical : Environment: The Mobil-developed additive converts toxic acid to a substantially safer form, engineering firm concludes. Torrance officials will weigh the report.

Mobil Oil Corp. should be allowed to use a modified form of the toxic chemical hydrofluoric acid at its refinery in Torrance, a safety adviser has concluded.

The city sued Mobil in 1989 over the safety of the refinery and concerns about the chemical, which forms a toxic ground-hugging cloud if it is released into the air. An agreement between Torrance and Mobil called on the refinery to stop using the acid by the end of 1997 unless it could find a safer form by Dec. 31, 1994.

But the court-monitored safety adviser, EQE Engineering in Irvine, said in a report released Tuesday that an additive developed by the oil company “can provide a substantial reduction in the potential risk” of the acid, which is used to boost the octane in unleaded gasoline.

The city and Mobil have until Feb. 2 to file any objections to the safety adviser’s conclusions. If no objections are raised, Mobil will be allowed to convert to the modified acid.

Torrance Fire Chief Scott Adams said he will spend the next several weeks “going over every detail” of the report.

Mobil officials hailed the additive as a breakthrough.

“This technology is a result of seven years of intense efforts on Mobil’s part, $50 million in expenditures, and was Mobil’s highest research and development priority,” Mobil said in a statement.

Without the additive, the refinery would have faced spending $100 million to switch to the industry alternative, sulfuric acid. Mobil has argued that sulfuric acid, although not as volatile on release, still poses a danger because much more of it is needed in the refining process, increasing the risk of an accident because more of it has to be trucked in.

But one environmentalist harbored doubts about the report’s methods, and called for more studies on Mobil’s additive before it is incorporated into refinery operations.

“Do people in Torrance want to be the subject of an experiment with an additive that was just created yesterday?” asked Fred Millar, a Washington-based environmentalist and longtime critic of hydrofluoric acid use.

Concerns over the safety of hydrofluoric acid were at the center of the lawsuit that Torrance filed against Mobil over the safety of the plant. Just two years earlier, a spill of the acid caused a major blaze that injured six people. It came just weeks after a Texas refinery accident that released a large cloud of the acid.

But the city and Mobil appeared to resolve their dispute in 1990 with the signing of a consent decree.

As part of the agreement, an adviser was appointed to oversee the safety at the plant. The pact, hailed by environmentalists and industry officials alike, required Mobil to show that the modified form “would not form an aerosol or dense vapor cloud upon release.”

In September, however, the city agreed to change the consent decree so Mobil instead could show that the modified acid would pose no greater risk than sulfuric acid.

“They changed the rules of the game so the safety adviser could come up with a report that was favorable to Mobil,” said Millar, the environmentalist.

The refinery was rocked Oct. 19 by an explosion that injured 28 workers. The cause of the accident, which occurred near the unit that uses hydrofluoric acid, remains under investigation.

EQE said that “it could be argued” that Mobil met “the spirit” of the original consent decree. City officials were primarily concerned over the acid’s tendency to form a ground-hugging cloud, rather than evaporating quickly or forming droplets.

Mobil, however, was able to show that the modified form no longer created an airborne aerosol, fine particles that help create the cloud. Yet vapors released from the modified acid still would be slightly denser than air and would not dissipate quickly, meaning that Mobil fell just short of meeting another provision of the original consent decree, EQE said. The report adds that the concentration of the vapors would not pose a serious danger.

“It flunks that test, yes,” said Torrance Fire Chief Adams. “It is still denser than air. But the report points out that they used the strictest definition you can possibly use and that the vapor cloud density does not significantly affect community impact.”

Adams and Mobil officials say that they changed the decree to give a better understanding of the merits of hydrofluoric acid versus sulfuric acid. The report compares the two through a quantitative risk assessment.

“We could have held their feet to the fire and forced them to spend $100 million on a process that could be a greater risk,” Adams said. “It makes no sense to me.”

Adams discussed the report with council members at a meeting Tuesday night.

“The end seems to have arrived, and I think the chief is pleased with the end result,” said Torrance Councilman Dan Walker, who once fought to phase out the use of the acid at Mobil. “I’m very pleased to look at a process that began a long time ago and ended with a safer refinery.”

Torrance Mayor Dee Hardison said she will depend on the fire chief and other experts to understand the report, but she still wants to know more about the possibility of a vapor cloud. “I think that is extremely important to the community.”

Times correspondent Mary Guthrie contributed to this story.