All 50,000 evacuees cleared to return home after chemical tank crisis at Southern California aerospace plant

Garden Grove Evacuations End After Chemical Tank Incident, 16,000 Residents Still Out

Garden Grove, Calif. – Evacuation orders that had forced roughly 50,000 residents to leave homes and businesses in and around the Orange County city are being lifted as authorities say a damaged tank of highly flammable methyl methacrylate (MMA) has been safely cooled and is no longer a threat of explosion.

The orders, first issued on Thursday following reports that a storage tank at the GKN Aerospace Transparency Systems plant had begun to overheat, were relaxed on Tuesday night. The final evacuation directive was for the neighborhood most adjacent to the tank. A meeting held that evening confirmed that residents within the remaining 16,000‑person zone could return home once the tank’s temperature had stayed stable for four consecutive hours without the aid of the sprinkler system.

A Crack, a Cool‑down and a Calm

During the Memorial Day weekend, emergency crews observed a crack forming in the tank that had been heating up to 100 °F (38 °C). The crack allowed some pressure to vent, averting a potentially catastrophic explosion. Water was sprayed onto the tank and a sprinkler system was activated, while firefighters stripped insulation and applied additional cooling water. By Tuesday, the tank’s interior temperature had dropped to 92 °F (33 °C).

“All residents will go home,” said Orange County Fire Authority Division Chief Craig Covey at the meeting. The statement was met with relief from residents who had been forced to leave their homes and the city’s commercial district for the past week.

The Incident’s Roots

The incident was traced to a failure in the cooling system designed to keep the MMA tanks at a safe temperature. Orange County Fire Authority Chief TJ McGovern explained that the malfunction caused heat to build up inside a pressurized tank holding approximately 7,000 gallons of the chemical. “We don’t know why, but it stopped cooling… So that’s what started this event, to where the product heated up and that’s how this whole response started. We’re just now being able to get to the tanks, so there’s definitely more to come of what caused it,” McGovern said.

Gov. Gavin Newsom declared a state of emergency on Saturday, shifting the response from defensive containment to “high‑risk offensive” actions aimed at preventing a blowout.

Health and Environmental Monitoring

Health officials have confirmed that air quality tests have not detected hazardous levels of MMA or related fumes. Monitoring of air, sewer systems and storm drains will continue for several months as a precaution. The Environmental Protection Agency lists MMA as capable of causing serious respiratory problems, neurological issues, and irritation to skin, eyes and throat.

Community and Company Responses

Mayor Stephanie Klopfenstein said she intends to hold GKN Aerospace accountable for the incident. “We need to understand why large quantities of this chemical were stored so close to homes and what safety practices were in place,” she told residents. GKN Aerospace released a statement saying, “We apologize for the ongoing disruption this incident is causing, and our priority remains the safety of our neighbors and our community.” The company added that it is working closely with authorities.

During the meeting, residents voiced concerns about the proximity of the chemical plant to residential neighborhoods and demanded a thorough review of the company’s safety protocols. City officials said they would examine zoning and safety oversight in the wake of the incident.

Looking Ahead

The final evacuation orders are being lifted, but the city and state officials stress that the situation remains under close observation. Residents who left during the crisis have been notified that they can return home once they receive confirmation that it is safe to do so.

Orange County authorities will continue to monitor the plant’s operations and the surrounding environment, while the state of emergency remains in effect. The incident serves as a reminder of the potential hazards associated with large‑scale chemical storage and the importance of robust safety systems.