Southern California chemical tank at risk of exploding as 40,000 residents are ordered to evacuate

But officials said that by Saturday the valves on the tank are broken or “gummed up,” so that prevented crews from removing the chemical or relieving the pressure on the tank, said Orange County Fire Authority Division Chief Craig Covey.

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’s 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 from the tank 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 Saturday that 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.

Tank wasn't cooling as first thought

Efforts to cool the tank appeared to be working Friday, but Covey backtracked Saturday, saying a reading conducted by drones actually showed the temperature on the outside of the tank, not the inside. Covey said emergency crews later were able to see the troubled tank’s temperature gauge in person late Friday.

“Unfortunately I do have to report that the temperature was 90 degrees,” Covey said Saturday. That was up from 77 degrees Friday morning.

Cooling the tank is important because the liquid chemical's flashpoint is 50 degrees Fahrenheit (10 degrees Celsius), according to the National Institute for Occupational Safety and Health.

Residents are frustrated and stressed

Initially, residents in Garden Grove were ordered to leave. Evacuation orders were expanded Friday to some residents of five other Orange County cities — Cypress, Stanton, Anaheim, Buena Park and Westminster. Some residents with pets said they planned to sleep in their cars.

Marco Solano, a 32-year-old resident, spent Friday night at his parents’ home. He said he was frustrated by the situation and was monitoring the news to see if he could go back to his home.

“I don’t think that they should have dangerous chemicals in a neighborhood area, especially that dangerous that they have to evacuate people,” Solano said. “But again, it's not up to me. I don’t make the laws. I don’t make the rules. We just have to do what is best I guess.”

Solano, who has multiple jobs, said he wasn’t feeling well Saturday, believing the stress of the chemical leak was exacerbating his anemia and ulcerative colitis.

“Right now I’m extremely tired. I have no energy. I’m super weak,” he said. “This has been affecting me quite a bit.”

He said he went to his apartment after work Friday to grab belongings and saw other residents who had not evacuated, and he was worried for them.

Exposure could lead to health problems

The damaged tank is located at GKN Aerospace, which makes parts for commercial and military aircraft. The tank holds between 6,000 and 7,000 gallons (22,700 and 26,500 liters) of methyl methacrylate, used to make plastic parts.

“Letting this thing just fail and blow up is simply unacceptable to us,” Covey said.

Officials said they expect “severe structural damage and significant harm” in the blast zone closest to the tank if there is an explosion.

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 this chemical is easy to smell, and residents may notice it over a large area without being harmed.

But Whelton said the volume of the chemical in the tank is much smaller than in the disastrous 2023 train derailment in East Palestine, Ohio, that he studied when more than 115,000 gallons of vinyl chloride was released after officials blew open five tank cars and burned that chemical.

Orange County is part of the Los Angeles metropolitan area where first responders are trained to respond to hazardous materials incidents, compared to the derailment in the small town near the Ohio-Pennsylvania border where the first responders were volunteer firefighters with less training and specialized equipment.

“Many of these are acute, fast-acting effects. But the longer somebody stays in contact with it, the more potential for significant damage that occurs,” Whelton said.

If an explosion releases the chemical into the air, Whelton said it will be crucial to conduct detailed air monitoring specifically for methyl methacrylate and not just conduct generic tests for volatile organic compounds as officials did in East Palestine. Those general tests often completed with handheld detectors may not be capable of detecting the chemical. Indoor tests of buildings and homes may also need to be done before residents return home.

If there is an explosion, the weather will be an important factor in determining where the plume of chemicals would go. Officials are developing maps to predict different scenarios about which areas would be most affected.

If the tank’s contents spill, containment barriers have been set up to prevent the chemical from getting into storm drains or reaching creeks or the nearby ocean, Covey said.

Emergency declaration

California Gov. Gavin Newsom on Saturday declared a state of emergency in Orange County. The declaration will make state resources available to local agencies and allow the use of state-owned properties and fairgrounds as shelter for residents if necessary.

Garden Groves is next to Anaheim, home to Disneyland’s two theme parks, which were not under evacuation orders as the Memorial Day weekend got underway. Park officials said they are monitoring the chemical incident and supporting park employees impacted by the evacuations.

Associated Press writers Dave Collins in Hartford, Connecticut, and Michael Blood in Los Angeles contributed to this story.