Overheated chemical tank may have cracked, California officials say

A damaged chemical tank in Southern California may have cracked — potentially lowering the risk of a cataclysmic explosion — though an evacuation order remains in effect for some 50,000 area residents with no timeline on when they can return, a fire official said Sunday.

Orange County Fire Authority Capt. Wayhowe Huang said officials will be continuing to evaluate the tank Sunday after emergency crews spotted the potential crack overnight. As of Sunday morning, he said it does not appear that any of the highly volatile chemicals in the tank have leaked.

“There’s still the danger of a possible explosion. We’re not taking that off the table,” Huang said. “We’re still operating as if that is the risk.”

Firefighters have been spraying the outside of the tank with water hoses in an effort to cool the chemicals heating up inside and prevent an explosion.

Lee Zeldin, head of the U.S. Environmental Protection Agency, said Sunday that the “most likely scenario” at this point is a “low-volume release,” where officials will be able to “monitor, neutralize and contain the threat.”

“The Orange County Fire Authority is working to keep the temperature of the tank down. That is very important,” he said on CNN, adding that keeping the temperature under 85 F (29.4 C) is key.

The pressurized tank overheated Thursday and began venting vapours at a company site in Garden Grove, about 50 kilometres southeast of downtown Los Angeles, according to the Orange County Fire Authority.

No injuries have been reported. Air monitoring tests have so far found that air pollution around the evacuation zone is within normal limits, and specialized equipment has been deployed to ensure no gas is released from the compromised tank, state and federal environmental officials said Saturday.

Officials said the valves on the tank are broken or “gummed up,” which prevented crews from removing the chemical or relieving the pressure on the tank, said Craig Covey, Orange County Fire Authority division chief.

Firefighters’ first hope is to find a way to cool off the chemical inside the tank so it won’t leak or explode. If that is not possible, Purdue University engineering professor Andrew Whelton said it would be best if the tank sprang a leak so the chemical could be mostly contained. An explosion that could spread the chemical over a broad area and send shrapnel flying would be the worst-case scenario.

If the temperature inside the tank continues to increase, the pressure will continue to build as the methyl methacrylate converts from a liquid to a gas, because officials said the pressure relief valves on the tank were no longer working. Whelton said it’s unlikely that firefighters would consider creating a hole in the tank because of fears that could create a spark that might ignite the volatile and flammable gas.

Efforts to cool the tank appeared to be working Friday, but Covey backtracked the following day, saying a reading conducted by drones actually showed the temperature on the outside of the tank, not the inside.

Cooling the tank is important because the liquid chemical’s flashpoint is 50 F (10 C), according to the National Institute for Occupational Safety and Health.

Residents file lawsuit

Meanwhile, some Garden Grove residents filed a class-action lawsuit on Saturday against GKN Aerospace Transparency Systems, the company that operates the facility where the tank is located.

Lawyers for residents living in the evacuation zone argued in their federal court lawsuit that regardless of what happens next, property values in the surrounding community are sure to be impacted.

“There is no good outcome here for the people who live nearby,” the lawyers wrote in a statement. “In the best-case scenario, a slow, controlled leak still forces residents out of their homes for an indefinite period, disrupting families, businesses and daily life. In the worst case, a catastrophic explosion could send a plume and debris across a far wider area, damaging thousands of properties and exposing residents to serious health risks.”

Spokespeople for the company didn’t comment on the lawsuit itself, but pointed to an earlier statement on the incident in which they apologized to residents and businesses that have been forced to evacuate.

“The situation remains ongoing and we are fully focused on working with emergency services, specialized hazardous, material teams and the relevant authorities to ensure the safety of the local community, our employees and everyone else involved,” the statement read.

The damaged tank is located at GKN Aerospace, which makes parts for commercial and military aircraft. It holds 22,700 and 26,500 litres of methyl methacrylate, used to make plastic parts.

Exposure to methyl methacrylate can cause serious respiratory problems and even render someone unconscious. It can also cause neurological problems and irritate the skin, eyes and throat, according to fact sheets about the chemical. But Orange County health officials said the chemical is easy to smell, and residents may notice it over a large area without being harmed.