Thousands evacuate as toxic tank at Garden Grove plant risks explosion

Firefighters in Garden Grove were left managing a tank they could not fully control: a 34,000-gallon vessel of methyl methacrylate that bulged, overheated and forced evacuation orders across Orange County. By Friday, officials said there was no active gas leak or plume, but the tank at GKN Aerospace was still “actively in crisis,” with only two bad outcomes left on the table.

The emergency began Thursday, May 21, with a vapor release from the tank at the aerospace manufacturing facility. By Friday, May 22, officials said the valves had become inoperable. That turned the response from containment into damage control. Authorities said the tank could fail and spill roughly 6,000 to 7,000 gallons of chemical, or go into thermal runaway and explode, risking nearby tanks as well.

Orange County Fire Authority crews used a curtain of sprayed water to hold down the tank’s temperature, buying time while experts from around the country weighed in with “outside-the-box” ideas. Fire officials said the situation was unprecedented and among the most dangerous they had encountered, a rare industrial emergency in which the best available tactic was to slow the clock.

The chemical involved, methyl methacrylate, is a flammable, volatile substance used to make resins, plastics and products such as Plexiglass. Health officials warned that if vapor escaped, prolonged exposure could cause severe respiratory problems. The Orange County Health Care Agency and fire officials urged residents to leave quickly, saying the risk was not theoretical if the tank gave way.

Evacuation orders expanded across parts of Garden Grove, Cypress, Stanton, Anaheim, Buena Park and Westminster, affecting about 40,000 to more than 44,000 people. Officials said about 15% of residents in the evacuation zone were refusing to leave even as the danger zone widened around the plant. Garden Grove Unified School District also closed schools or canceled outdoor activities in the area as police and fire crews pushed people to move out.

The tank remained the center of the response Friday evening, with officials hoping overnight efforts would allow crews to get closer and find a long-term fix. For now, the industrial site had become a mass-evacuation threat, and the difference between a controlled burn and a catastrophic failure still depended on a tank that no one could safely let alone.