Evacuation Lifted for Some Residents Near Hazardous Chemical Tank in Southern California

Evacuation Order Partially Lifted

Emergency officials in Southern California have lifted the evacuation order for some residents living near a damaged tank containing a hazardous chemical. The decision came after temperatures inside the tank fell, reducing the risk of a catastrophic explosion at the GKN Aerospace Transparency Systems plant in Garden Grove. Although the major explosion risk has diminished, the possibility of smaller blasts or fires remains, according to Orange County Fire Authority division chief Craig Covey.

Following an overnight assessment, a crack in the tank was discovered, allowing pressure reduction inside the vessel. The tank holds 6,000 to 7,000 gallons of methyl methacrylate, a highly flammable substance. Consequently, approximately two-thirds of the evacuated residents, around 34,000 people, have been allowed to return home.

Ongoing Concerns and Monitoring

Covey emphasized that while progress has been made, challenges persist, including mitigating fire and explosion risks, and preventing potential spills. The initial evacuation order affected around 50,000 residents after the tank overheated.

The tank’s temperature has been lowered to 93 degrees Fahrenheit from 100 degrees the previous day, according to officials. This temperature drop was crucial in preventing a toxic leak or explosion. Orange County Health Director Regina Chinsio-Kwong assured returning residents of their safety, citing no contamination, fumes, vapors, or leaks from the incident.

Andrew Whelton, a Purdue University engineering professor, noted that while some risk remains, temperatures need to fall closer to ambient levels—around 60 to 70 degrees Fahrenheit—before conditions are considered safer. As temperatures rose, methyl methacrylate inside the tank converted to gas, increasing pressure and explosion risk. However, parts of the chemical may have already become stable plastic, akin to plexiglass, reducing internal risk.

Environmental and Public Safety Measures

Orange County Supervisor Janet Nguyen announced the South Coast Air Quality Management District’s plans to monitor air quality for several months, along with EPA checks on sewer and storm drains. Despite the chemical being detectable by smell, it poses no harm over a large area.

Public Reaction and Company Response

Authorities have reassured the public that a catastrophic explosion scenario is now unlikely. Evacuated resident Kim Yen expressed relief upon learning the situation has improved, though she remains cautious about returning home.

Residents have sheltered in Fountain Valley’s park during the evacuation. The affected plant belongs to GKN Aerospace, a British company specializing in aircraft component manufacture, employing approximately 16,000 people globally. Measures were taken to cool the tank contents with the removal of external insulation.

GKN Aerospace regretted disruption caused by the incident and prioritized safe resolution. The company has settled past violations with state regulators, paying over $900,000 for recordkeeping, permitting, and emission issues.

Impact on the Aerospace Industry

According to Richard Aboulafia, managing director of AeroDynamic Advisory, global aerospace supply chains remain vulnerable to disruptions due to concentrated operations producing specialized components. Aerospace manufacturing features relatively low production rates, limiting suppliers for essential parts and systems.