Summary
Southern California officials kept evacuation orders in place into the Memorial Day weekend for about 40,000 residents near a damaged chemical tank in Garden Grove, Orange County, as firefighters worked to prevent the tank from leaking or exploding. The tank began venting vapors after it overheated Thursday at a company site, and Orange County fire officials said they reported no injuries at that point.
Fire officials said the engineering challenge was that the tank could not be safely stabilized the way crews had hoped. Orange County Fire Authority division chief Craig Covey said the valves on the tank were broken or “gummed up,” preventing teams from removing the chemical or relieving pressure inside the tank.
At the start of the incident, Garden Grove residents were ordered to leave, and officials later expanded evacuation orders to parts of five other Orange County cities: Cypress, Stanton, Anaheim, Buena Park and Westminster. Several shelters remained open Saturday, including at three high schools, and some residents said they planned to sleep in cars as they waited for the situation to change.
Firefighters’ immediate priority was to cool the chemical inside the tank so it would not leak or explode. Purdue University engineering professor Andrew Whelton said firefighters’ best option was to cool the tank, but he also discussed the consequences if pressure continued to rise and the tank did release material—saying that, in a worst-case view, it would be better for the tank to “spring a leak” so the chemical could be mostly contained rather than detonating.
Officials said the chemical inside the tank was methyl methacrylate, which can shift from a liquid to a gas as temperatures rise, building pressure if the tank’s pressure relief system is not functioning. Covey said drones were monitoring temperatures at 10-minute intervals to watch for spikes, and he said planning was underway to stop any release from spreading into waterways or the ocean.
Covey later revised the cooling updates after initial indications that the tank temperature was dropping. He said a reading conducted by drones showed the temperature on the outside of the tank rather than the inside, and he reported “Unfortunately I do have to report that the temperature was 90 degrees,” up from 77 the previous morning.
On the health side, Orange County health officials said methyl methacrylate exposure can cause serious respiratory problems and can even render someone unconscious, and they said it can also cause neurological problems and irritate the skin, eyes and throat. They also said the chemical is easy to smell and residents may notice it over a large area without being harmed.
Whelton, discussing what emergency crews would need to do if an explosion released the chemical, compared the situation to a 2023 derailment in East Palestine, Ohio, which he said he studied. He said many effects from such chemicals can be acute and fast-acting, but that longer exposure increases the potential for significant damage; he added that if a release happened, officials would need detailed air monitoring specific to methyl methacrylate rather than only generic volatile organic compound tests.
Gov. Gavin Newsom declared a state of emergency in Orange County, making state resources available to local agencies and allowing state-owned properties and fairgrounds to be used for shelters if needed. Garden Grove, adjacent to Anaheim, sits near Disneyland, whose theme parks were not under evacuation orders, and park officials said they were monitoring the incident and supporting employees affected by evacuations.
Covey said officials also set up containment barriers to prevent the chemical from getting into storm drains or reaching creeks or the nearby ocean in the event of a spill. He said, “Sitting back and allowing these tanks to fail is unacceptable,” adding that his goal was to protect homes and the environment even if officials did not rule out the possibility that tanks could breach and leak.
A resident, Marco Solano, said he spent Friday night at his parents’ home and was frustrated by the uncertainty. Solano said he believed dangerous chemicals should not be in a neighborhood, while also saying, “But again, it’s not up to me,” as evacuation rules kept him away from parts of his area and he worried for residents who had not evacuated.