Overheating Chemical Tank at GKN Aerospace Triggers Massive Evacuation in Garden Grove

A pressurized tank holding 6,000-7,000 gallons of methyl methacrylate (MMA) at GKN Aerospace’s Garden Grove plant vented on May 21. Internal temperature rose from 77 °F to 90 °F by May 22, raising pressure and the risk of a 7,000-gallon spill or explosion. OCFA crews sprayed water, then shifted to an “offensive” cooling strategy after drone scans showed only exterior temperature drops.

CNBC

• Overheating detected; relief valve and sprinklers activated.

CNBC

• Drone scans showed exterior cooling; internal gauge later read 90 °F.

Reuters

• OCFA moved to offensive tactics, adding chemists and high-flow water.

Reuters

• EPA, state monitors found no MMA vapor; shelters filled, lawsuits filed.

USA Today

Division chief Craig Covey (OCFA) directed water cooling, drone monitoring and contingency diking. Governor Gavin Newsom declared a state emergency, unlocking resources for shelters and evacuations. EPA Administrator Lee Zeldin sent 24 monitors and stressed keeping the tank cool. Health Officer Dr. Regina Chinsio-Kwong urged residents to stay outside the evacuation zone. GKN Aerospace apologized and pledged cooperation with hazardous-materials teams.

USA Today

Evacuation orders covered roughly 40,000-50,000 residents; shelters in Anaheim, Fountain Valley, La Palma and Huntington Beach filled, prompting extra sites at Golden West College. About 15 % (?6,000) refused to leave. Some evacuees reported throat irritation, dizziness and headaches despite monitors showing no MMA. Two law firms filed a class-action suit, warning that any outcome—leak or explosion—will depress property values and citing a 2020 $900,000 VOC-violation settlement.

CNN

Sources differ on evacuee numbers (40,000 vs. 50,000). Early drone data suggested exterior cooling, but internal gauges later showed rising temperatures. Official monitors have not detected vapor, yet some residents report symptoms, leaving exposure risk uncertain. No timeline has been set for lifting evacuations or confirming tank integrity.

USA Today

• “letting this thing just fail and blow up is unacceptable to us.” — Craig Covey, OCFA Division Chief

USA Today

• “You are safe as long as you are out of the zone that was determined to be an evacuation zone,” — Dr. Regina Chinsio-Kwong, Orange County Health Care Agency

Reuters

• “There is no good outcome here for the people who live nearby,” — Plaintiffs’ attorneys, class-action lawsuit

CNBC

• “The Orange County Fire Authority is working to keep the temperature of the tank down. That is very important,” — Lee Zeldin, EPA Administrator

CNBC

Fire crews will keep high-volume water cooling while drones track temperature spikes. State and federal agencies will maintain round-the-clock air-quality monitoring and may add shelter capacity. Legal proceedings will address compensation, and a post-incident investigation will assess the tank’s integrity and regulatory compliance.

USA Today