Officials in Orange County, California, recently announced a new evacuation map, significantly reducing the emergency evacuation zone related to a hazardous methyl methacrylate (mma) chemical tank incident at the GKN Aerospace facility in Garden Grove. This decision came after authorities determined the explosion risk had been eliminated.

The revised evacuation zone now covers only parts of Garden Grove and Stanton. Its boundaries extend from Dale Street to Knott Avenue and from Orangewood Avenue to Garden Grove Boulevard, impacting approximately 16,000 residents. Orange County Health Officer Regina Chinsio Kwong confirmed the air in the area is safe, with no toxic fumes or smoke emanating from the tank.

Orange County's updated evacuation map. *Graphic: CBS News*

This reduced zone represents approximately 35% of the original evacuation area, allowing 34,000 residents to return home after four days of seeking shelter at temporary sites or with friends and family.

Craig Covey, a section chief with the Orange County Fire Authority, explained the mitigation efforts. Firefighters used a maximum capacity water spray system, discharging over 4,700 liters of water per minute to cool the tank. This action prevented the mma chemical inside from continuing its exothermic reaction, which could have led to an explosion.

Covey reported that millions of liters of water were used in this process, keeping the tank's temperature within controlled limits. He added that most of the chemical in the tank likely converted to a gel or solid form during the reaction.

"This water was continuously monitored and confirmed to be 100% clean, without chemical contamination throughout its use," Covey stated. He assured residents in the formerly evacuated zone that they do not need to spray wash their homes, outdoor furniture, or pathways to remove chemicals. "If chemicals escaped during the initial phase of the incident, they settled immediately near the tank," he said, emphasizing that "there was no wind or other factors to spread the chemicals, apart from the increasing pressure inside the tank."

Orange County fire officials stated the tank's temperature will continue to decrease as firefighters and plant personnel remove the external insulation from the tank walls and continue spraying cooling water.

"I understand this incident disrupted many families' lives. It's a relief that many can return home," stated Garden Grove Mayor Stephanie Klopfenstein.

Water being sprayed onto the leaking chemical tank in Garden Grove, California, on 23/5. *Photo: AP*

California Governor Gavin Newsom's office announced on 25/5 that President Donald Trump approved the state's request for an emergency declaration to support incident response efforts.

This approval allows Orange County to receive federal emergency funding for activities such as: evacuation, temporary shelter arrangements, emergency medical support, and other protective measures for residents. It also covers overtime pay, equipment, and other necessary emergency operations.

By Duc Trung (Based on Voice of OC, CBS News, KTLA)