Firefighters in southern California have eliminated the threat of an explosion from an overheating chemical tank, Orange County fire officials confirmed on Monday. The damaged tank, containing methyl methacrylate, cracked over the weekend, which authorities hoped would relieve pressure and reduce the risk of a blast.
Overnight operations allowed crews to verify the crack and confirm that temperatures inside the tank were falling, said Orange County Fire Authority Division Chief Craig Covey. He described the results as “incredibly positive news.” Some 50,000 residents in Garden Grove and surrounding areas had been evacuated since Thursday, when the tank began venting vapours.
The tank, located at GKN Aerospace Transparency Systems, holds between 6,000 and 7,000 gallons of methyl methacrylate, a chemical used to make plastic parts. Firefighters have been spraying the tank with water to cool it, and drones monitored temperatures at 10-minute intervals. The interior temperature reached 100F (37.7C) on Sunday.
President Donald Trump approved a federal emergency declaration following a request from California Governor Gavin Newsom, making federal assistance available through FEMA. Air pollution monitoring found levels within normal limits, and containment barriers have been set up to prevent chemical spills from reaching storm drains or waterways.
Experts said the crack likely reduced pressure, lowering the explosion risk. However, Purdue University engineering professor Andrew Whelton cautioned that the chemical remains reactive while hot, and temperatures need to fall to around 60-70F (15.6-21.1C) for conditions to be significantly safer. Crews aim to stabilise and drain the remaining material without triggering ignition.
Evacuation shelters remain open, with some residents sleeping at a high school in La Palma. Garden Grove is adjacent to Anaheim, home to Disneyland, which was not under evacuation orders. GKN Aerospace, which employs about 16,000 people globally, settled violations with state regulators in 2025 for over $900,000.
