Why Garden Grove chemical explosion could be so catastrophic

Key Points:

• A chemical tank containing about 7,000 gallons of methyl methacrylate (MMA) at GKN Aerospace in Orange County is at risk of exploding, prompting evacuation orders for approximately 40,000 residents in parts of Garden Grove, Anaheim, Buena Park, Cypress, Stanton, and Westminster.
• MMA is a highly toxic, flammable chemical that can cause severe respiratory distress, nausea, dizziness, and skin irritation; an explosion could release a dangerous vapor plume that settles in low-lying areas, posing significant health risks.
• Efforts to stabilize or drain the compromised tank have been hindered by broken and gummed-up valves, preventing the addition of neutralizing chemicals or safe removal of the liquid, while emergency crews continue cooling the tank with water to delay failure.
• No active chemical leak was reported as of Friday afternoon, with drones monitoring the tank’s temperature to provide advance warning of potential thermal runaway and explosion, and authorities are preparing for evacuation if necessary.
• Most residents are complying with evacuation orders, though about 15% are refusing to leave; the evacuation zone extends roughly one to three miles from the tank, affecting nearby residential areas and prompting precautionary measures beyond the zone, including at the Westminster courthouse.