Emergency officials have lifted the evacuation order for certain residents near a damaged tank containing a hazardous chemical in Southern California. This decision followed a decrease in temperatures within the tank, reducing the risk of a catastrophic explosion.
Orange County Fire Authority Division Chief Craig Covey announced there is no longer a major explosion risk at the GKN Aerospace Transparency Systems plant in Garden Grove. However, he highlighted the remaining potential for minor blasts or fires. During a news conference, Covey noted the reduction in pressure within the tank containing 6,000 to 7,000 gallons (22,700 to 26,500 liters) of methyl methacrylate, a flammable chemical, due to a crack discovered on Sunday. As a result, roughly two-thirds of the evacuated 50,000 residents can return home.
Covey expressed that work to mitigate potential fire, minor explosion, and spill risks is still ongoing. Following the overheating of the tank, residents in Garden Grove, near Los Angeles, were ordered to evacuate. By the weekend, approximately 50,000 residents were affected.
Covey stated that cooling the tank remains a priority to prevent a toxic leak or explosion. By Monday, the tank’s temperature had decreased to 93 degrees Fahrenheit (33.9 degrees Celsius) from 100 degrees Fahrenheit (37.7 degrees Celsius) the previous day.
Orange County Health Director Regina Chinsio-Kwong assured returning residents of their safety, highlighting that no contamination, fumes, or vapors were released during the incident. She stressed that residents returning home, even those living across the street from the new zone line, should feel secure.
Environmental Risks Persist
Crews aim to cool the tank sufficiently to stabilize and safely drain its contents without igniting a spark. Andrew Whelton, a Purdue University engineering professor, cautioned about the remaining risk of explosion while the chemical continues to react. The tank conditions will be significantly safer when temperatures approach ambient levels, approximately 60 to 70 degrees Fahrenheit (15.6 to 21.1 degrees Celsius).
As the tank’s interior heated, methyl methacrylate converted from liquid to gas, increasing pressure and explosion risk. Whelton noted some of the chemical might have solidified into a stable plastic, akin to plexiglass, reducing risk.
Orange County Supervisor Janet Nguyen stated that the South Coast Air Quality Management District will monitor air quality for several months. Additionally, the EPA will inspect the sewer and storm drains.
County health officials have mentioned the chemical’s odor might be detectable over a wide area without causing harm.
Residents Relieved by Latest Update
Authorities have clarified that a catastrophic explosion scenario has been ruled out. Affected resident Kim Yen expressed relief upon learning the critical danger has passed. She remains cautious, desiring confirmation that it is safe to return home. Yen also praised the emergency crews, stating, “They are really our heroes.”
The parking lot of a large park in Fountain Valley, southwest of Garden Grove, accommodated numerous evacuees seeking refuge or enjoying Memorial Day.
About GKN Aerospace
GKN Aerospace Transparency Systems, owned by a British company, produces cockpit windows, canopies, and windshields for military and civilian aircraft. A GKN Aerospace statement disclosed that technical specialists, with assistance from the Orange County Fire Authority, removed external insulation from the tank to cool it effectively.
“We apologize for the ongoing disruption this incident is causing, and our priority remains its safe resolution, so that residents can return home as quickly as possible,” the statement noted.
GKN Aerospace employs around 16,000 individuals across 32 manufacturing sites in 12 countries, supplying technology and components to commercial and military aircraft manufacturers globally. The timeline for facility reopening remains uncertain.
In 2025, GKN Aerospace had agreed to pay over $900,000 to settle violations involving record-keeping, permitting, and nitrogen oxide emissions per a report from the South Coast Air Quality Management District.
Aircraft Manufacturing and Supply Chain Risks
Richard Aboulafia of AeroDynamic Advisory emphasized the challenges faced by the global aerospace industry due to disruptions at facilities producing specialized aircraft components. Due to concentrated supply chains, the impacts are more profound as aircraft production rates are relatively low. This leaves few suppliers for specialized parts and systems, offering little margin in the industry.