Orange County officials lifted evacuation orders for tens of thousands of residents on Tuesday after firefighters successfully cooled an overheated chemical tank at a Garden Grove aerospace facility, eliminating the immediate threat of a catastrophic explosion. The tank, containing 7,000 gallons of flammable methyl methacrylate (MMA), had been at risk of a boiling liquid expanding vapor explosion (BLEVE) due to thermal runaway. Firefighters sprayed over 9 million gallons of water to reduce the tank's temperature, which caused a crack that relieved pressure, preventing a disaster.
Officials declare area safe
Orange County health and fire officials stated that air monitors detected no toxic vapors or chemical leaks, allowing residents to return home. The U.S. Environmental Protection Agency (EPA) confirmed no detectable levels of MMA or other volatile organic compounds in the surrounding air. Disneyland Resort, located about five miles from the site, remained open and unaffected by the evacuation zone.
Experts raise concerns
Despite official assurances, environmental experts expressed skepticism. Andrew Whelton, a Purdue University professor, argued that the cracked tank likely released some toxic substances, though water suppression may have mitigated airborne risks. Fire officials had previously warned that the tank's thermal runaway could have led to an explosion or spill.
Cause of the crisis
Interim Orange County Fire Authority Chief TJ McGovern attributed the incident to a cooling system failure, which allowed the tank to overheat. The exact cause remains under investigation. Authorities emphasized that the situation had stabilized, but further evaluations are ongoing.