All remaining evacuation orders were lifted in Orange County on Tuesday evening as authorities declared there was no remaining danger of an explosion, chemical leak or fire stemming from a hazardous material incident at an aerospace manufacturing plant.
Around 50,000 people in six Orange County cities were told to evacuate during the crisis, when an overheating tank filled with 7,000 gallons of a chemical called methyl methacrylate — a highly flammable liquid monomer used to manufacture plastics — was at risk of causing a massive explosion.
At 7:30 pm Tuesday, 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 at GKN Aerospace had reduced the pressure inside, drastically lowering the risk of an explosion, according to interim Orange County Fire Authority Chief TJ McGovern. Crews were then able to peel back the external wall and insulation and closely target their water hoses to continue cooling the chemical inside, McGovern said.
Officials had announced Monday morning that the risk of a BLEVE, or boiling liquid expanding vapor explosion, had been eliminated after crews sprayed more than 9 million gallons of water onto the tank.
As a result, the evacuation zone was initially reduced Monday evening, allowing some 34,000 residents to return home.
On Tuesday, crews remained focused on stabilizing the temperature of the tank to eliminate any remaining fire risk and on monitoring runoff to ensure no contaminated water escaped.
The tank was sitting at 92 degrees on Monday morning, according to Fire Authority spokesperson Greg Barta. Crews then turned off the water stream and closely evaluated the response.
Craig Covey, division chief with the Orange County Fire Authority, interrupted a community meeting in Garden Grove on Tuesday evening to break the news to residents that all evacuations were being lifted.
“I just got positive news that the tank [temperature] stayed stable since the three or four hours that we turned the water off,” he said. “I didn’t want to delay you getting home tonight. “I’m sorry to do this right in the middle of this meeting, but this is more important than anything else.”
Out of an “abundance of caution,” a 300-foot exclusion zone, which does not affect any residents, 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.
The six-day chemical crisis began inside the GKN Aerospace facility in Garden Grove and was probably caused by the failure of a cooling system designed to regulate the temperature of chemical tanks, McGovern said.
Multiple lawsuits have already been filed against the aerospace manufacturing company seeking compensation for residents exposed to danger and forced to evacuate.
The Fire Authority initially responded to the incident Thursday afternoon by dousing the tank in water and issuing an evacuation order for surrounding streets that was lifted that evening.
But by Friday morning, the severity of the crisis became apparent as crews were unable to neutralize and remove the chemical.
The tank was deemed at risk of causing a catastrophic explosion and sweeping evacuation orders were issued affecting residents in areas of Garden Grove, Cypress, Stanton, Anaheim, Buena Park and Westminster.
The Orange County health officer and fire officials have insisted there have been no toxic chemicals released over the course of the emergency.
“There was no contamination, there were no fumes, there were no vapors that came from this incident,” Dr. Regina Chinsio-Kwong, county health officer, said Monday. “There was no leak.”
Some environmental experts have expressed skepticism over this claim, arguing that it is likely at least some vapors escaped from the crack in the tank.
Times staff writers Hannah Fry and Tony Briscoe contributed to this report.
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