Firefighters in southern California have eliminated the threat of an explosion at a chemical tank that overheated and began venting hazardous vapours, Orange County fire officials confirmed on Monday. The tank, located at GKN Aerospace Transparency Systems in Garden Grove, holds between 6,000 and 7,000 gallons of methyl methacrylate, a chemical used to make plastic parts.
The crisis began on Thursday when the tank overheated, prompting the evacuation of around 50,000 residents from Garden Grove and surrounding areas. Officials feared a potential explosion or leak of the chemical, which can cause serious respiratory and neurological problems, as well as skin, eye and throat irritation.
Overnight operations on Sunday allowed crews to safely monitor the tank's temperature and verify a crack that had formed, which helped relieve pressure. Orange County fire division chief Craig Covey described the results as 'incredibly positive news', noting that the temperature inside had dropped and pressure had been released.
President Donald Trump approved a federal emergency declaration following a request from California Governor Gavin Newsom, making federal assistance available through the Federal Emergency Management Agency (FEMA). Firefighters had repeatedly sprayed the tank with water to cool the chemical, which reached an interior temperature of 100°F (37.7°C) on Sunday.
Drones monitored temperatures at 10-minute intervals, and containment barriers were set up to prevent any spill from reaching storm drains or waterways. Air pollution tests around the evacuation zone remained within normal limits, according to state and federal environmental officials.
Residents remained in evacuation shelters, including a high school in neighbouring La Palma, while awaiting further updates. The tank is expected to be stabilised and drained once it cools to ambient levels of around 60-70°F (15.6-21.1°C), though officials cautioned that some risk remains while the chemical is still hot and reactive.
