The remaining 16,000 residents of a Southern California town were allowed to return home Tuesday, days after the threat of a catastrophic explosion at a chemical tank sparked fears of an environmental catastrophe.
The crisis in the 7,000-gallon tank of the toxic and flammable chemical methyl methacrylate at GKN Aerospace in Garden Grove, first detected Thursday, had prompted the evacuation of tens of thousands of people.
As of Tuesday evening, there was no longer any danger of an explosion, no chemical leaks, no threat of fire and no risk to the public, Orange County firefighters said.
“All evacuation orders related to the hazardous materials incident in Garden Grove have been lifted,” the agency said.
At its height, the emergency forced about 60,000 people in Garden Grove and nearby towns from their homes. Most evacuation orders were lifted on Monday, but around 16,000 people were told to stay away as there remained a low risk of fire or explosion.
Some residents at a community meeting Tuesday questioned why hazardous chemicals were allowed at facilities in Garden Grove, a city of about 171,000 people 35 miles southeast of Los Angeles.
Mayor Stephanie Klopfenstein said investigations would be conducted at the city, state and federal levels.
“Our community deserves to know what happened, why it happened and whether any laws or regulations were violated,” she said.
Firefighters responded to a 911 call at 3:22 p.m. Thursday about an active leak at GKN Aerospace, Orange County Incident Commander Craig Covey said at the meeting, and found a pressure valve atop one of three tanks releasing steam.
A problem with a valve in the refrigeration system, supposed to keep the tank at 50 degrees Fahrenheit, had caused it to overheat, he said.
“That tank was about to explode,” Covey said.
The company’s sprinklers were on and trying to cool the tank, he said, and firefighters used a water jet dumping 1,250 gallons per minute on it.
“These cooling measures were effective; they reduced the pressure,” Covey said.
A gauge showed the reservoir reached at least 100 degrees over the weekend, Covey said. Tuesday, the temperature in the main tank remained at 92 degrees, firefighters said.
A crack on the tank also helped relieve pressure and allowed crews to take more aggressive action. If the worst fear — a boiling liquid expanding vapor explosion, or BLEVE — had occurred, it would have been a disaster, officials said.
A GKN spokesperson said earlier Tuesday that “we continue to work around the clock” with the Orange County Fire Authority, the Environmental Protection Agency and others.
“We apologize for the continued disruption caused by this incident, and our priority remains the safety of our neighbors and community,” the spokesperson said in a statement.
