Chemical Crisis in Garden Grove — A City’s Week of Fear

Garden Grove, California — Early in the evening of May 21, first responders with the Orange County Fire Authority received an alert that would set off one of the most dramatic hazardous materials emergencies Southern California had seen in years. At approximately 3:40 p.m. PDT, the OCFA was notified of a hazardous materials incident at the GKN Aerospace facility in Garden Grove. Upon arriving at the scene, crews determined that a 34,000-gallon tank containing approximately 7,000 gallons of a chemical called methyl methacrylate had begun to overheat and off-gas vapor.

Methyl methacrylate, or MMA, is a flammable liquid used primarily in plastics manufacturing and aerospace materials. Under normal conditions, it sits inertly in large industrial vessels. But when a tank’s temperature begins to rise uncontrolled, MMA becomes extraordinarily dangerous. The risks are numerous — methyl methacrylate can irritate the skin and eyes, cause respiratory issues, and produce neurological symptoms including headaches and lethargy. Long-term exposure can cause lung and organ damage.

By Friday, May 22, the scale of the emergency had become clear. Some 50,000 residents of Garden Grove remained under an evacuation order as emergency response teams struggled to deal with a potentially explosive situation at the nearby aerospace manufacturing plant. Families loaded their cars with pets, medications, and whatever valuables they could carry and headed to evacuation shelters across Orange County.

The threat was not abstract. Firefighters and hazmat specialists warned of a phenomenon known as a BLEVE — a boiling liquid expanding vapor explosion — which can produce a catastrophic fireball. Authorities warned there were many factors that could contribute to the tank’s demise, which is why they expanded the evacuation orders to such a large area. Notably, the industrial site where the tank is located sits about five miles from Disneyland and about four miles from Knott’s Berry Farm — both parks remained open and outside the evacuation zone.

Emergency crews worked in shifts, continuously spraying the overheated vessel with water to bring the temperature down. Officials on scene added a neutralizer to the methyl methacrylate in a neighboring Tank #2 to prevent an even worse chain reaction. The process was slow and uncertain, requiring days of sustained effort before any meaningful reduction in risk was achieved.

Compounding public frustration were revelations about prior regulatory failures. Inspectors found that GKN Aerospace had operated new equipment without securing a permit and used existing equipment that did not match the description in its permit. The company also modified permitted equipment without applying for a required permit change, and received two orders to fix the issues — in December 2020 and February 2021 — but failed to comply.

Monday evening, conditions had improved enough for evacuation orders to be partially lifted. Authorities expanded their focus overnight to cooling efforts after finding that pressure in the tank had been alleviated, preventing the disaster known as a BLEVE. On Tuesday, improving data allowed crews to shut off an unmanned water hose — a small but meaningful milestone after nearly a week of sustained crisis management.

For the residents of Garden Grove, the episode exposed not only the potential dangers of industrial facilities situated within dense residential communities, but the significant consequences of deferred regulatory compliance. Investigations are expected to continue in the weeks ahead.