Newsom Lifts Evacuations After Garden Grove Chemical Crisis Stabilizes

California Governor Gavin Newsom declared a state of emergency on Saturday due to a critical situation at the GKN Aerospace facility in Garden Grove involving a chemical tank containing methyl methacrylate (MMA). The crisis originated when damage to a valve on the tank prevented complete mitigation, causing it to overheat and begin venting vapors into the air. According to multiple sources, evacuations were ordered for up to 50,000 people across six cities: Garden Grove, Cypress, Stanton, Anaheim, Buena Park, and Westminster.

The situation worsened overnight despite initial efforts by hazmat teams to stabilize it. Orange County Fire Authority Division Chief Craig Covey warned that the tank was 'actively in crisis' with two possible outcomes: failing and spilling its contents or going into thermal runaway and exploding. Firefighters have been dousing the tank with water using a mechanical device to keep humans at a safe distance, which has stabilized the temperature and bought time.

According to AP News, authorities confirmed on Monday that the risk of a catastrophic explosion had been eliminated following an overnight inspection that confirmed a crack in the tank relieved pressure and cooled the chemical. The storage tank contained about 6,000 to 7,000 gallons (22,713 to 26,498 liters) of methyl methacrylate used to make plastic parts. Officials had feared that the tank could leak all the chemical or even explode.

BBC reported that Orange County Fire Authority Interim Chief TJ McGovern said on Monday that the tank's temperature has decreased, which led to the 'positive news'. The tank's internal temperature decreased from 100F (38C) to 93F (34C). Despite efforts to cool the tank, its internal temperature rose from 77 degrees Fahrenheit on Friday morning to 90 degrees by Saturday. The temperature was increasing by about one degree per hour.

The chemical MMA is highly volatile and toxic, capable of causing severe respiratory distress if inhaled at high levels. Health officials expressed concern that vapor could cause severe respiratory issues but air quality monitors detected no such vapor as per Reuters. The evacuation zone extends roughly between one to three miles away from the failing chemical tank, with residential homes situated less than 400 feet east of the tank in Stanton.

According to CBS News, crews conducted tank temperature checks at night to reduce risks to firefighters, avoiding daytime operations when heat from the tank made conditions around it most dangerous. The overnight mission allowed crews to verify the crack and confirm temperatures were falling. Covey said the results of overnight evaluation of the tank — that the temperature inside had dropped and that pressure had been released — was 'incredibly positive news.' However, evacuation orders remained in place for about 50,000 people in Garden Grove.

UPI reported that Orange County Fire Authority Interim Chief T.J. McGovern said in a video update that the possibility of destructive blast was over. Covey also confirmed that efforts by firefighters to cool the tank by continually dousing it with water have been successful. The temperature has been stabilized and is actually reducing, he said. It is currently 93 degrees, down from 100 degrees.

All evacuation orders were lifted on Tuesday evening as authorities declared there was no remaining danger of an explosion, chemical leak or fire stemming from the hazardous material incident at GKN Aerospace. The Orange County Fire Authority announced that the decision to fully repopulate the evacuation zone was made in coordination with law enforcement, the Environmental Protection Agency and the Orange County Public Health Department.

Evaluations over Memorial Day weekend found that a crack in the tank had reduced pressure inside, drastically lowering the risk of an explosion. Crews were then able to peel back the external wall and insulation and closely target their water hoses to continue cooling the chemical inside. Officials announced Monday morning that more than 9 million gallons of water had been sprayed onto the tank.

Out of an 'abundance of caution,' a 300-foot exclusion zone remains in place around the tanks as hazardous materials crews continue monitoring conditions. A road closure is also in effect along Western Avenue between Chapman and Garden Grove boulevards.